JP7628819B2 - Internally meshing planetary gear device, wheel device and vehicle - Google Patents

Description

This disclosure relates generally to an internally meshed planetary gear device, a wheel device, and a vehicle, and more specifically to an internally meshed planetary gear device, a wheel device, and a vehicle in which a planetary gear having external teeth is arranged inside an internal gear having internal teeth.

As a related technique, a so-called eccentric oscillating type gear device is known in which a planetary gear eccentrically oscillates and internally meshes with an internal gear (see, for example, Patent Document 1). In the gear device according to the related technique, an eccentric body is formed integrally with the input shaft, and the planetary gear is attached to the eccentric body via an eccentric body bearing. External teeth, such as a circular-arc tooth shape, are formed on the outer periphery of the planetary gear.

The internal gear is constructed by rotatably assembling a number of outer pins (roller pins), each of which constitutes an internal tooth, onto the inner peripheral surface of a gear body (internal gear body) that also serves as a casing. A number of loose fitting holes (inner roller holes) are formed in the planetary gear at appropriate intervals in the circumferential direction, into which the inner pins and inner rollers are inserted. The inner pins are connected to a carrier at one end in the axial direction, and the carrier is rotatably supported by the casing via a cross roller bearing. This gear device can be used as a gear device that extracts from the carrier a rotation equivalent to the rotation component of the planetary gear when the internal gear is fixed.

JP 2003-74646 A

In the configuration of the related art described above, cross roller bearings are used as bearing members, and the relatively complex structure of the cross roller bearings can hinder simplification of the structure of the internal meshing planetary gear device as a whole.

The objective of this disclosure is to provide an internally meshed planetary gear device, a wheel device, and a vehicle that can be easily simplified in structure.

An internally meshing planetary gear device according to one aspect of the present disclosure includes an internal gear, a planetary gear, a plurality of internal pins, a first bearing member, and a second bearing member. The internal gear has an annular gear body and a plurality of external pins that are held on the inner peripheral surface of the gear body in a rotatable state and form internal teeth. The planetary gear has external teeth that partially mesh with the internal teeth. The internal pins rotate relative to the gear body while revolving within the loose fitting holes while being inserted into a plurality of loose fitting holes formed in the planetary gear. The first bearing member and the second bearing member rotatably support the multiple internal pins with respect to the gear body at two points in the rotation axis direction. The first bearing member has a first inner ring, a first outer ring, and multiple bearing pins. The multiple internal pins are located inside the second bearing member when viewed from one side of the rotation axis direction.

A wheel device according to one aspect of the present disclosure includes the internally meshing planetary gear device and a wheel body that rolls on a running surface due to the rotational output generated when the multiple inner pins rotate relative to the gear body.

A vehicle according to one aspect of the present disclosure includes the wheel device and a vehicle body that holds the wheel device.

This disclosure makes it possible to provide an internally meshed planetary gear device, a wheel device, and a vehicle that are easy to simplify in structure.

FIG. 1A is a perspective view showing a schematic configuration of an internal meshing planetary gear device according to a first embodiment, as viewed from the output side of a rotating shaft. FIG. 1B is a perspective view showing a schematic configuration of the internal meshing planetary gear device of the above, as viewed from the input side of the rotary shaft. FIG. 2 is a schematic exploded perspective view of the internal meshing planetary gear device as viewed from the output side of the rotary shaft. FIG. 3 is a schematic cross-sectional view of the internal meshing planetary gear device. FIG. 4 is a cross-sectional view taken along line A1-A1 in FIG. 3, showing the internal meshing planetary gear device, and a partially enlarged view thereof. FIG. 5 is a perspective view showing the configuration of the internal gear and the planetary gears of the internal meshing planetary gear device. FIG. 6 is an exploded perspective view showing the configuration of the internal gear and the planetary gears of the internal meshing planetary gear device. FIG. 7 is a cross-sectional view taken along line B1-B1 in FIG. 3, showing the internal meshing planetary gear device, and a partially enlarged view thereof. FIG. 8 is a perspective view mainly showing the configuration of the first bearing member and its periphery in the internal meshing planetary gear device. FIG. 9 is an exploded perspective view mainly showing the configuration of the first bearing member and its periphery in the internal meshing planetary gear device. FIG. 10 is an enlarged view of an area Z1 in FIG. 3, showing the internal meshing planetary gear device. FIG. 11 is a schematic perspective view of a wheel device and a vehicle using the above internal meshing planetary gear device. FIG. 12 is an enlarged view equivalent to FIG. 10 , showing an internal meshing planetary gear device according to a modified example of the first embodiment. FIG. 13 is a schematic cross-sectional view of an internal meshing planetary gear device according to the second embodiment. FIG. 14 is a cross-sectional view taken along line B1-B1 in FIG. 13, showing the internal meshing planetary gear device, and a partially enlarged view thereof. FIG. 15 is an enlarged view equivalent to FIG. 10 , showing an internal meshing planetary gear device according to a modified example of the second embodiment. FIG. 16 is a schematic cross-sectional view of an internal meshing planetary gear device according to the third embodiment. FIG. 17 is a cross-sectional view taken along line B1-B1 in FIG. 16, showing the internal meshing planetary gear device, and a partially enlarged view thereof.

(Embodiment 1)
(1) Overview An overview of the internally meshing planetary gear device 1 according to this embodiment will be described below with reference to Figures 1A to 4. All of the drawings referred to in this disclosure are schematic diagrams, and the ratios of sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. For example, the tooth shapes, dimensions, number of teeth, etc. of the internal teeth 21 and external teeth 31 in Figures 1A to 4 are merely shown schematically for the purpose of explanation, and are not intended to be limited to the shapes shown in the drawings.

The internally meshing planetary gear device 1 (hereinafter, simply referred to as "gear device 1") according to this embodiment is a gear device including an internal gear 2 (see FIG. 4), a planetary gear 3, and a number of internal pins 4. In this gear device 1, the planetary gear 3 is disposed inside the annular internal gear 2, and an eccentric bearing 5 is disposed inside the planetary gear 3. The eccentric bearing 5 has an eccentric inner ring 51 and an eccentric outer ring 52, and the planetary gear 3 is oscillated by the eccentric inner ring 51 rotating (eccentric motion) around a rotation axis Ax1 (see FIG. 3) that is offset from the center C1 (see FIG. 3) of the eccentric inner ring 51. The eccentric inner ring 51 rotates (eccentric motion) around the rotation axis Ax1, as shown in FIG. 4, for example, by the rotation of an eccentric shaft 54 inserted into the eccentric inner ring 51.

The internal gear 2 has internal teeth 21. In particular, in this embodiment, the internal gear 2 has an annular gear body 22 and multiple external pins 23. The multiple external pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state, forming the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. In other words, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and a part of the external teeth 31 is meshed with a part of the internal teeth 21. In this state, when the eccentric shaft 54 rotates, the planetary gear 3 oscillates, and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and a relative rotation according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). If the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in response to the relative rotation of the two gears. As a result, the planetary gear 3 produces a rotational output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

This type of gear device 1 is used to extract the relative rotation between the planetary gear 3 and the internal gear 2, i.e., the rotation equivalent to the rotation component of the planetary gear 3 when the internal gear 2 is fixed, as, for example, the relative rotation of the rotating member with respect to the fixed member. In short, the gear device 1 rotates the rotating member with its output while the fixed member is fixed. As a result, the gear device 1 functions as a gear device with a relatively high reduction ratio, with the eccentric shaft 54 as the input side and the rotating member as the output side. Therefore, in the gear device 1 according to this embodiment, in order to transmit the relative rotation between the planetary gear 3 and the internal gear 2 to the fixed member and the rotating member, the gear body 22 is fixed to one of the fixed member and the rotating member, and the planetary gear 3 is connected to the other of the fixed member and the rotating member with multiple inner pins 4.

The multiple inner pins 4 rotate relative to the internal gear 2 while revolving within the multiple loose fitting holes 32, respectively, while being inserted into the multiple loose fitting holes 32 formed in the planetary gear 3. In other words, the loose fitting holes 32 have a larger diameter than the inner pins 4, and the inner pins 4 can move to revolve within the loose fitting holes 32 while being inserted into the loose fitting holes 32. The oscillation component of the planetary gear 3, i.e., the revolution component of the planetary gear 3, is absorbed by the loose fitting between the loose fitting holes 32 of the planetary gear 3 and the inner pins 4. In other words, the oscillation component of the planetary gear 3 is absorbed by the multiple inner pins 4 moving to revolve within the multiple loose fitting holes 32, respectively. Therefore, the rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the fixed member or rotating member by the multiple inner pins 4.

In this way, the relative rotation between the planetary gear 3 and the internal gear 2 is transmitted to the fixed member and the rotating member as the relative rotation between the gear body 22 and the multiple internal pins 4. Therefore, in the gear device 1, a reduced rotation output can be obtained from either the planetary gear 3 or the internal gear 2. That is, for example, when the gear body 22 is fixed to a fixed member, the planetary gear 3 is connected to the rotating member by the multiple internal pins 4, so the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the planetary gear 3. On the other hand, when the gear body 22 is fixed to a rotating member, the planetary gear 3 is connected to the fixed member by the multiple internal pins 4, so the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the internal gear 2.

The gear device 1 also includes a (first) bearing member 6. The bearing member 6 includes a (first) inner ring 61 and a (first) outer ring 62. The inner ring 61 is disposed inside the outer ring 62 and is supported rotatably relative to the outer ring 62. The bearing member 6 is a component for rotatably supporting a rotating member relative to a fixed member. In other words, the (first) bearing member 6 is a component for rotatably supporting a plurality of inner pins 4 relative to the gear body 22. In the gear device 1, the rotating member is supported in a rotatable state relative to the fixed member by the bearing member 6, and as a result, the relative rotation between the planetary gear 3 and the internal gear 2 can be output as the rotation of the rotating member relative to the fixed member.

In this type of gear device 1, it is known that a cross roller bearing is used as a bearing member in a related technique. In a cross roller bearing, the axis of a cylindrical rolling element (roller) is inclined at 45 degrees with respect to a plane perpendicular to the rotation axis Ax1 and perpendicular to the outer periphery of the inner ring, and further, the axes of a pair of adjacent rolling elements in the circumferential direction of the inner ring are perpendicular to each other. That is, in the gear device 1, depending on its application, loads in various directions such as a radial load, a thrust load (direction along the rotation axis Ax1), and a bending force (bending moment load) against the rotation axis Ax1 can act. In the related technique, a cross roller bearing is used as a bearing member so that it can withstand these loads in various directions. However, since a cross roller bearing is used as a bearing member in the related technique, the cross roller bearing, which has a relatively complicated structure, may hinder the simplification of the structure of the gear device 1 as a whole. The gear device 1 according to this embodiment has the following configuration, making it possible to provide an internally meshing planetary gear device 1 that is easy to simplify in structure.

That is, the gear device 1 according to this embodiment includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, a first bearing member 6, and a second bearing member 7, as shown in Figs. 1 to 3. The internal gear 2 has an annular gear body 22 and a plurality of outer pins 23 that are held on the inner peripheral surface 221 of the gear body 22 in a rotatable state and form the internal teeth 21. The planetary gear 3 has an outer tooth 31 that partially meshes with the internal teeth 21. The inner pins 4 are inserted into a plurality of loose fitting holes 32 formed in the planetary gear 3, and rotate relative to the gear body 22 while revolving within the loose fitting holes 32. The first bearing member 6 and the second bearing member 7 support the inner pins 4 rotatably relative to the gear body 22 at two points in the direction of the rotation axis Ax1. Here, the first bearing member 6 has a first inner ring 61, a first outer ring 62, and a plurality of bearing pins 63. Furthermore, the multiple inner pins 4 are located inside the second bearing member 7 when viewed from one side in the direction of the rotation axis Ax1.

According to this embodiment, the first bearing member 6 and the second bearing member 7 rotatably support the multiple inner pins 4 relative to the gear body 22 at two points in the direction of the rotation axis Ax1, so that the multiple inner pins 4 are supported at two points relative to the gear body 22. Therefore, compared to a single-point support in which the multiple inner pins 4 are supported relative to the gear body 22 at one point in the direction of the rotation axis Ax1, it is easier to withstand loads such as bending forces (bending moment loads) relative to the rotation axis Ax1. Moreover, the first bearing member 6 has a first inner ring 61, a first outer ring 62, and multiple bearing pins 63. In other words, the first bearing member 6 is a needle bearing in which the bearing pins 63 are "rolling bodies (rollers)", and can withstand relatively large loads in the radial direction. Furthermore, even though it is a two-point support, since the second bearing member 7 is located outside the multiple inner pins 4 when viewed from one side in the direction of the rotation axis Ax1, the limited space inside the multiple inner pins 4 can be made to have a relatively simple structure. Therefore, compared to related techniques that use cross roller bearings as bearing members, the gear device 1 according to this embodiment has the advantage that it is easier to simplify the structure.

Furthermore, because cross roller bearings are expensive bearing components, the configuration of the gear device 1 according to this embodiment makes it possible to omit such cross roller bearings, which has the advantage of making it easier to reduce costs.

(2) Definition In the present disclosure, "annular" means a ring-like shape that forms an enclosed space (region) at least in a plan view, and is not limited to a circular shape (annular shape) such as a perfect circle in a plan view, but may be, for example, an elliptical shape, a polygonal shape, etc. Furthermore, even if the shape has a bottom, such as a cup shape, it is included in the "annular" shape as long as the peripheral wall is annular.

In this disclosure, "loose fit" means being fitted with play (gap), and the loose fit hole 32 is a hole into which the inner pin 4 is loosely fitted. In other words, the inner pin 4 is inserted into the loose fit hole 32 with a spatial margin (gap) secured between the inner circumferential surface of the loose fit hole 32. In other words, the diameter of at least the portion of the inner pin 4 inserted into the loose fit hole 32 is smaller (thinner) than the diameter of the loose fit hole 32. Therefore, the inner pin 4 can move within the loose fit hole 32 when inserted into the loose fit hole 32, that is, it can move relatively to the center of the loose fit hole 32. Therefore, the inner pin 4 can revolve within the loose fit hole 32. However, it is not essential that a gap as a cavity is secured between the inner circumferential surface of the loose fit hole 32 and the inner pin 4, and for example, this gap may be filled with a fluid such as a liquid.

In this disclosure, "revolution" means that an object revolves around an axis of rotation other than the central axis that passes through the center (center of gravity) of the object, and when an object revolves, the center of the object moves along an orbital path centered on the axis of rotation. Therefore, for example, when an object rotates around an eccentric axis that is parallel to the central axis that passes through the center (center of gravity) of the object, the object revolves around the eccentric axis as the axis of rotation. As an example, the inner pin 4 revolves within the loose fitting hole 32, revolving around the axis of rotation that passes through the center of the loose fitting hole 32.

In addition, in this disclosure, one side of the rotation axis Ax1 (right side in FIG. 3) may be referred to as the "input side," and the other side of the rotation axis Ax1 (left side in FIG. 3) may be referred to as the "output side." In the example of FIG. 3, rotation is imparted to the rotor (eccentric inner ring 51) from the "input side" of the rotation axis Ax1, and relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the "output side" of the rotation axis Ax1. However, the "input side" and "output side" are merely labels added for the purpose of explanation, and are not intended to limit the positional relationship between the input and output as viewed from the gear device 1.

In this disclosure, the term "rotation axis" refers to a virtual axis (straight line) that is the center of rotational motion of a rotating body. In other words, the rotation axis Ax1 is a virtual axis that does not have a physical entity. The eccentric inner ring 51 rotates around the rotation axis Ax1.

In this disclosure, "internal teeth" and "external teeth" do not refer to individual "tooths," but rather to a collection (group) of multiple "teeth." In other words, the internal teeth 21 of the internal gear 2 are made up of a collection of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are made up of a collection of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

(3) Configuration Hereinafter, a detailed configuration of the internal meshing planetary gear device 1 according to this embodiment will be described with reference to FIGS. 1A to 10.

1A shows a schematic configuration of the gear device 1, and is a perspective view of the gear device 1 as seen from the output side of the rotation axis Ax1 (left side of FIG. 3). FIG. 1B shows a schematic configuration of the gear device 1, and is a perspective view of the gear device 1 as seen from the input side of the rotation axis Ax1 (right side of FIG. 3). FIG. 2 is a schematic exploded perspective view of the gear device 1 as seen from the output side of the rotation axis Ax1. FIG. 3 is a schematic cross-sectional view of the gear device 1. FIG. 4 is a cross-sectional view of line A1-A1 in FIG. 3, and a partially enlarged view thereof. FIG. 5 is a perspective view mainly showing the configuration around the internal gear 2 and planetary gear 3 of the gear device 1, and FIG. 6 is an exploded perspective view thereof. FIG. 7 is a cross-sectional view of line B1-B1 in FIG. 3, and a partially enlarged view thereof. FIG. 8 is a perspective view mainly showing the configuration around the first bearing member 6 of the gear device 1, and FIG. 9 is an exploded perspective view thereof. FIG. 10 is an enlarged view of area Z1 in FIG. 3. However, in Figures 4 and 7, hatching has been omitted for parts other than the eccentric shaft 54, even in cross sections.

(3.1) Overall Configuration As shown in Figures 1A to 3, the gear device 1 according to this embodiment includes an internal gear 2, a planetary gear 3, a plurality of inner pins 4, an eccentric body bearing 5, a first bearing member 6, a second bearing member 7, an eccentric shaft 54, and a support member 8. In this embodiment, the gear device 1 further includes a retaining member 55, a balance weight 56, a first bearing 91, a second bearing 92, a spacer 93, and a case 10. In this embodiment, the materials of the components of the gear device 1, such as the internal gear 2, the planetary gear 3, the plurality of inner pins 4, the eccentric body bearing 5, the first bearing member 6, and the second bearing member 7, are metals such as stainless steel, cast iron, carbon steel for mechanical construction, chromium molybdenum steel, phosphor bronze, or aluminum bronze. Furthermore, the materials of the eccentric shaft 54, the support member 8, the retaining member 55, the balance weight 56, and the case 10 are also metals similar to those described above. The metal referred to here includes metals that have been subjected to surface treatment such as nitriding.

In addition, in this embodiment, an internal planetary gear device using a trochoidal tooth profile is illustrated as an example of the gear device 1. In other words, the gear device 1 according to this embodiment includes an internal planetary gear 3 having a trochoidal curved tooth profile.

In addition, in this embodiment, as an example, the gear device 1 is used in a state where a holding member 55 (see FIG. 2) that holds the multiple inner pins 4 is fixed to a fixed member (such as the hub member 14 described later). That is, the planetary gear 3 is connected to a fixed member by the multiple inner pins 4, and the gear body 22 is fixed to a rotating member (such as the body portion 11 described later), so that the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the internal gear 2. In other words, in this embodiment, when the multiple inner pins 4 rotate relative to the gear body 22, the rotational force of the gear body 22 is extracted as an output.

In addition, as an example, the gear device 1 is used in the wheel device W1 (see FIG. 11), which will be described in detail later. In this case, the rotating member (body 11, etc.) functions as the wheel body 102 (see FIG. 11), and the wheel body 102 can be rotated in accordance with the relative rotation of the internal gear 2 and the planetary gear 3. In this way, in this embodiment, by using the gear device 1 in the wheel device W1, the wheel body 102 can be driven so as to roll on the running surface by the rotation output when the multiple inner pins 4 rotate relative to the gear body 22. In short, when the gear device 1 is used as the wheel device W1, a rotation force as an input is applied to the eccentric shaft 54, and a rotation force as an output is taken out from the rotating member (body 11, etc.) as the wheel body 102. In other words, the gear device 1 operates with the rotation of the eccentric shaft 54 as the input rotation and the rotation of the rotating member (body 11, etc.) to which the gear body 22 is fixed as the output rotation. As a result, the gear device 1 obtains output rotation that is reduced by a relatively high reduction ratio compared to the input rotation as the rotation of the wheel body 102.

Furthermore, in the gear device 1 according to this embodiment, as shown in FIG. 3, the input side rotation axis Ax1 and the output side rotation axis Ax1 are on the same straight line. In other words, the input side rotation axis Ax1 and the output side rotation axis Ax1 are coaxial. Here, the input side rotation axis Ax1 is the rotation center of the eccentric shaft 54 to which the input rotation is applied, and the output side rotation axis Ax1 is the rotation center of the gear body 22 which generates the output rotation. In other words, in the gear device 1, an output rotation that is reduced in speed at a relatively high reduction ratio compared to the input rotation is obtained on the same axis.

As shown in Figures 1A and 1B, the case 10 is cylindrical and forms the outer shell of the gear device 1. In this embodiment, the case 10 functions as the wheel main body 102, so the central axis of the cylindrical case 10 is configured to coincide with the rotation axis Ax1. In other words, at least the outer peripheral surface of the case 10 is a perfect circle centered on the rotation axis Ax1 in a plan view (seen from one side in the direction of the rotation axis Ax1).

The case 10 has a body 11, a cap 12, a ring cap 13, and a hub member 14. The body 11 is a cylindrical part with both end faces in the direction of the rotation axis Ax1 open. The cap 12 is a disk-shaped part attached to the end face of the output side (left side in FIG. 3) of the rotation axis Ax1 in the body 11 and closes the open face of the output side of the rotation axis Ax1 in the body 11. The ring cap 13 is an annular part attached to the end face of the input side (right side in FIG. 3) of the rotation axis Ax1 in the body 11. The hub member 14 is an annular part arranged inside the ring cap 13. A part of the open face of the input side of the rotation axis Ax1 in the body 11 is closed by the hub member 14. Here, the body 11, the cap 12, the ring cap 13, and the hub member 14 are all formed in a perfect circle centered on the rotation axis Ax1 in a plan view.

A plurality of (eight, for example) screw holes 111 (see FIG. 5 ) are formed on the end face of the output side of the rotation axis Ax1 in the body 11. The plurality of screw holes 111 are used to fix the cap 12 to the body 11. Specifically, a plurality of (eight, for example) fixing screws 151 are fastened to the screw holes 111 through the cap 12, thereby fixing the cap 12 to the body 11. A plurality of (eight, for example) screw holes 112 (see FIG. 8 ) are formed around the end face of the input side of the rotation axis Ax1 in the body 11. The plurality of screw holes 112 are used to fix the ring cap 13 to the body 11. Specifically, a plurality of (eight, for example) fixing screws 152 are fastened to the screw holes 112 through the ring cap 13, thereby fixing the ring cap 13 to the body 11.

Then, the space surrounded by the body 11, the cap 12, the ring cap 13, and the hub member 14, that is, the internal space of the case 10, contains the internal gear 2, the planetary gear 3, the multiple inner pins 4, the eccentric bearing 5, the first bearing member 6, the second bearing member 7, the support 8, and the like. The hub member 14 is attached to a holding member 55 that holds the multiple inner pins 4 from the input side of the rotation axis Ax1. A multiple number (eight, for example) of screw holes 554 (see FIG. 9 ) are formed on the end face of the holding member 55 on the input side of the rotation axis Ax1. The multiple screw holes 554 are used to fix the hub member 14 to the holding member 55. Specifically, a multiple number (eight, for example) of fixing screws 153 are fastened to the screw holes 554 through the hub member 14, thereby fixing the hub member 14 to the holding member 55.

Here, a plurality of (four as an example) fixing holes 141 (see FIG. 1B) are formed on the end surface of the input side of the rotation axis Ax1 in the hub member 14. The plurality of fixing holes 141 are used to fix the hub member 14. In this embodiment, the gear device 1 is used in the wheel device W1, so that the hub member 14 is fixed to the vehicle body 100 (see FIG. 11) to which the wheel device W1 is attached. Specifically, the hub member 14 is fixed to the vehicle body 100 by fastening a plurality of (four as an example) fixing screws through a part of the vehicle body 100 and fastening them to the fixing holes 141. In this way, the hub member 14 is fixed to the vehicle body 100 even in the case 10 that constitutes the wheel main body 102, and constitutes a "fixed member" that does not rotate even when the gear device 1 is driven. On the other hand, the body 11, the cap 12, and the ring cap 13 constitute a "rotating member" that rotates relative to the hub member 14 when the gear device 1 is driven. In other words, when the multiple inner pins 4 rotate relative to the gear body 22, the rotation of the rotating members (body 11, cap 12, and ring cap 13) relative to the fixed member (hub member 14) is taken out as the output of the gear device 1. When the case 10 is used as the wheel body 102, these rotating members rotate and roll on the running surface.

The ring cap 13, which is a rotating member, and the hub member 14, which is a fixed member, are configured to be relatively rotatable around the rotation axis Ax1. Specifically, the outer diameter of the hub member 14 is smaller than the inner diameter of the ring cap 13, and when the hub member 14 is disposed inside the ring cap 13, a gap is created between the hub member 14 and the ring cap 13.

The hub member 14 also has a through hole 142 in the center when viewed from above that passes through the hub member 14 in the direction of the rotation axis Ax1. The through hole 142 is a hole for passing the eccentric shaft 54 through. The hub member 14 and the eccentric shaft 54 are configured to be relatively rotatable around the rotation axis Ax1. Specifically, the inner diameter of the hub member 14 (the diameter of the through hole 142) is larger than the outer diameter of the eccentric shaft 54 (the shaft center portion 541), and when the eccentric shaft 54 is inserted through the through hole 142, a gap is generated between the hub member 14 and the eccentric shaft 54.

Furthermore, in this embodiment, the outer peripheral surface of the body 11, which is a rotating member, becomes the contact surface with the running surface of the wheel body 102, i.e., the ground contact surface. For this reason, for example, a rubber tire 103 is attached to the outer peripheral surface of the body 11. In Figures 1A and 1B, the tire 103 is shown by an imaginary line (two-dot chain line).

In this embodiment, the gear body 22 of the internal gear 2, the first outer ring 62 of the first bearing member 6, and the second outer ring 72 of the second bearing member 7 are fixed to the body 11, which is a rotating member. Here, as an example, the gear body 22 and the first outer ring 62 are integrated with the body 11. The body 11 has an outer ring fixing frame 74 (see FIG. 10) for fixing the second outer ring 72. In particular, in this embodiment, the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 are integrally formed from a single metal member, and thus the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 are treated as a seamless single part (body 11). The gear body 22, the first outer ring 62, and the outer ring fixing frame 74 are arranged in the order of the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 from the output side of the rotation axis Ax1. Therefore, as shown in FIG. 2, the inner circumferential surface of the body 11 includes the inner circumferential surface 221 of the gear body 22 and the inner circumferential surface 621 of the first outer ring 62.

The internal gear 2 is an annular part having internal teeth 21, as shown in Figs. 4 to 6. In this embodiment, the internal gear 2 has an annular shape, with at least the inner peripheral surface being a perfect circle in a plan view. The internal teeth 21 are formed along the circumferential direction of the internal gear 2 on the inner peripheral surface of the annular internal gear 2. The multiple teeth constituting the internal teeth 21 all have the same shape, and are provided at equal pitch over the entire circumferential area of the inner peripheral surface of the internal gear 2. In other words, the pitch circle of the internal teeth 21 is a perfect circle in a plan view. The center of the pitch circle of the internal teeth 21 is on the rotation axis Ax1. The internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. All of the tooth traces of the internal teeth 21 are parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth trace direction is slightly smaller than the thickness direction of the internal gear 2.

Here, as described above, the internal gear 2 has an annular (circular) gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state, and constitute the internal teeth 21. In other words, the plurality of outer pins 23 function as a plurality of teeth that constitute the internal teeth 21. Specifically, as shown in FIG. 6, a plurality of grooves are formed on the inner circumferential surface 221 of the gear body 22 over the entire circumferential direction. These grooves are a plurality of gear grooves 222 (see FIG. 4) that serve as a holding structure for the plurality of outer pins 23. In other words, the holding structure for the plurality of outer pins 23 includes a plurality of gear grooves 222 formed on the inner circumferential surface 221 of the gear body 22. The plurality of gear grooves 222 are all of the same shape and are provided at equal pitches. All of the plurality of gear grooves 222 are parallel to the rotation axis Ax1, and are formed over the entire width of the gear body 22.

However, in this embodiment, as described above, the gear body 22 is part of the body 11, and therefore the multiple gear grooves 222 are formed only in the portion of the body 11 that corresponds to the gear body 22 (see FIG. 10). The multiple outer pins 23 are combined with the gear body 22 (body 11) so as to fit into the multiple gear grooves 222. Each of the multiple outer pins 23 is held in a rotatable state within the gear groove 222, and the gear groove 222 restricts the movement of the gear body 22 in the circumferential direction.

As shown in Figures 4 to 6, the planetary gear 3 is an annular part having external teeth 31. In this embodiment, the planetary gear 3 has an annular shape in which at least the outer peripheral surface is a perfect circle in a plan view. The outer peripheral surface of the annular planetary gear 3 is formed with external teeth 31 along the circumferential direction of the planetary gear 3. The multiple teeth constituting the external teeth 31 all have the same shape and are provided at equal pitch over the entire circumferential area of the outer peripheral surface of the planetary gear 3. In other words, the pitch circle of the external teeth 31 is a perfect circle in a plan view. The center C1 of the pitch circle of the external teeth 31 is shifted from the rotation axis Ax1 by a distance ΔL (see Figure 4). The planetary gear 3 also has a predetermined thickness in the direction of the rotation axis Ax1. All of the external teeth 31 are formed over the entire length of the planetary gear 3 in the thickness direction. All of the tooth traces of the external teeth 31 are parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 are formed integrally with the main body of the planetary gear 3 from a single metal member.

Here, the eccentric body bearing 5 and the eccentric shaft 54 are combined with the planetary gear 3. That is, the planetary gear 3 has an opening 33 that opens in a circular shape, as shown in Figures 5 and 6. The opening 33 is a hole that penetrates the planetary gear 3 along the thickness direction. In a plan view, the center of the opening 33 and the center of the planetary gear 3 coincide with each other, and the inner circumferential surface of the opening 33 (the inner circumferential surface of the planetary gear 3) and the pitch circle of the external teeth 31 are concentric. The opening 33 of the planetary gear 3 accommodates the eccentric body bearing 5. Furthermore, the eccentric shaft 54 is inserted into the eccentric body bearing 5 (the eccentric inner ring 51), so that the eccentric body bearing 5 and the eccentric shaft 54 are combined with the planetary gear 3. When the eccentric shaft 54 rotates with the eccentric body bearing 5 and the eccentric shaft 54 combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

The planetary gear 3 configured in this manner is disposed inside the internal gear 2. In a plan view, the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 can oscillate inside the internal gear 2 when combined with the internal gear 2. Here, external teeth 31 are formed on the outer peripheral surface of the planetary gear 3, and internal teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gear 3 is disposed inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

Furthermore, the pitch circle of the external teeth 31 is one size smaller than the pitch circle of the internal teeth 21. And, when the planetary gear 3 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 is located at a position shifted by a distance ΔL (see FIG. 4) from the center of the pitch circle of the internal teeth 21 (rotation axis Ax1). Therefore, the external teeth 31 and the internal teeth 21 face each other at least partially through a gap, and do not mesh with each other in the entire circumferential direction. However, since the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, the external teeth 31 and the internal teeth 21 partially mesh with each other. In other words, by oscillating the planetary gear 3 around the rotation axis Ax1, some of the teeth that make up the external teeth 31 mesh with some of the teeth that make up the internal teeth 21, as shown in FIG. 4. As a result, in the gear device 1, it is possible to mesh some of the external teeth 31 with some of the internal teeth 21.

Here, the number of teeth of the internal teeth 21 of the internal gear 2 is N (N is a positive integer) more than the number of teeth of the external teeth 31 of the planetary gear 3. In this embodiment, as an example, N is "1", and the number of teeth (of the external teeth 31) of the planetary gear 3 is "1" more than the number of teeth (of the internal teeth 21) of the internal gear 2. Such a difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear device 1.

In addition, in this embodiment, as an example, the thickness of the planetary gear 3 is smaller than the thickness of the gear body 22 in the internal gear 2. Strictly speaking, the thickness of the planetary gear 3 is smaller than the dimension of the portion of the body 11 that functions as the gear body 22 (see FIG. 10) in a direction parallel to the rotation axis Ax1. Furthermore, the dimension of the external teeth 31 in the tooth trace direction (direction parallel to the rotation axis Ax1) is smaller than the dimension of the internal teeth 21 in the tooth trace direction (direction parallel to the rotation axis Ax1). In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 are contained within the range of the tooth trace of the internal teeth 21.

In this embodiment, as described above, the relative rotation between the planetary gear 3 and the internal gear 2 is transmitted to the fixed member and the rotating member as the relative rotation between the gear body 22 and the multiple inner pins 4. As shown in Figures 5 and 6, the planetary gear 3 has multiple loose fitting holes 32 for inserting the multiple inner pins 4. The number of loose fitting holes 32 is the same as the number of inner pins 4, and in this embodiment, as an example, eight loose fitting holes 32 and eight inner pins 4 are provided. Each of the multiple loose fitting holes 32 has a circular opening and is a hole that penetrates the planetary gear 3 along the thickness direction. The multiple (here, eight) loose fitting holes 32 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the opening 33.

The multiple inner pins 4 are components that connect the planetary gear 3 to a fixed member or a rotating member. In this embodiment, the planetary gear 3 is connected to a fixed member (hub member 14, etc.) by the multiple inner pins 4, and the gear body 22 is fixed to a rotating member (body portion 11, etc.). Therefore, the planetary gear 3 is directly or indirectly connected to the fixed member (hub member 14, etc.) by the multiple inner pins 4. Each of the multiple inner pins 4 is formed in a cylindrical shape. The diameter and length of the multiple inner pins 4 are common to the multiple inner pins 4. The diameter of the inner pin 4 is one size smaller than the diameter of the loose fitting hole 32. As a result, the inner pin 4 is inserted into the loose fitting hole 32 with a spatial margin (gap) secured between the inner peripheral surface of the loose fitting hole 32 (see Figures 4 and 5).

The retaining member 55 is a part that retains the multiple inner pins 4. In this embodiment, as shown in FIG. 8 and FIG. 9, the retaining member 55 is formed in a perfect circular shape centered on the rotation axis Ax1 in a plan view and is formed to be approximately the same size as the hub member 14. The retaining member 55 has multiple retaining holes 551 into which the multiple inner pins 4 are respectively inserted. The retaining holes 551 are provided in the same number as the inner pins 4, and in this embodiment, as an example, eight retaining holes 551 are provided. Each of the multiple retaining holes 551 has a circular opening and is a hole that penetrates the retaining member 55 along the thickness direction. The multiple (here, eight) retaining holes 551 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer periphery of the retaining member 55. The diameter of the retaining hole 551 is equal to or greater than the diameter of the inner pin 4 and smaller than the diameter of the loose fitting hole 32.

In this embodiment, the diameter of the retaining hole 551 is approximately the same as the diameter of the inner pin 4, and is slightly larger than the diameter of the inner pin 4. Therefore, the movement of the inner pin 4 within the retaining hole 551 is restricted, that is, the movement relative to the center of the retaining hole 551 is prohibited. Therefore, the inner pin 4 is held in a state in which it can revolve within the loose fitting hole 32 in the planetary gear 3, and is held in a state in which it cannot revolve within the retaining hole 551 relative to the retaining member 55. As a result, the oscillation component of the planetary gear 3, that is, the revolution component of the planetary gear 3, is absorbed by the loose fitting between the loose fitting hole 32 and the inner pin 4, and the rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the retaining member 55 by the multiple inner pins 4.

Furthermore, in this embodiment, the diameter of the inner pin 4 is slightly larger than the retaining hole 551, so that while the inner pin 4 is inserted into the retaining hole 551, it is prohibited from revolving within the retaining hole 551, but is able to rotate within the retaining hole 551. In other words, even when the inner pin 4 is inserted into the retaining hole 551, it is not pressed into the retaining hole 551, and is therefore able to rotate within the retaining hole 551. In this way, in the gear device 1 according to this embodiment, each of the multiple inner pins 4 is held by the retaining member 55 in a rotatable state, so that the inner pin 4 itself can rotate when it revolves within the loose fitting hole 32.

In short, in this embodiment, the inner pin 4 is held in a state in which it can both revolve and rotate within the loose fitting hole 32 relative to the planetary gear 3, and is held in a state in which it can only rotate within the holding hole 551 relative to the holding member 55. In other words, the multiple inner pins 4 can revolve within the multiple loose fitting holes 32 with their rotation not restricted (rotatable state). Therefore, when the multiple inner pins 4 transmit the rotation (rotation component) of the planetary gear 3 to the holding member 55, the inner pin 4 can rotate within the holding hole 551 while revolving and rotating within the loose fitting hole 32. Therefore, when the inner pin 4 revolves within the loose fitting hole 32, the inner pin 4 is in a rotatable state and rolls against the inner peripheral surface of the loose fitting hole 32. In other words, the inner pin 4 revolves within the loose-fitting hole 32 by rolling on the inner circumferential surface of the loose-fitting hole 32, so losses due to frictional resistance between the inner circumferential surface of the loose-fitting hole 32 and the inner pin 4 are unlikely to occur.

In this way, in the configuration according to this embodiment, since loss due to frictional resistance between the inner peripheral surface of the loose fitting hole 32 and the inner pin 4 is unlikely to occur in the first place, it is possible to omit the inner roller. Therefore, in this embodiment, a configuration is adopted in which each of the multiple inner pins 4 directly contacts the inner peripheral surface of the loose fitting hole 32. In other words, in this embodiment, the inner pin 4 without the inner roller attached is inserted into the loose fitting hole 32, and the inner pin 4 directly contacts the inner peripheral surface of the loose fitting hole 32. As a result, the inner roller can be omitted and the diameter of the loose fitting hole 32 can be kept relatively small, making it possible to reduce the size of the planetary gear 3 (especially the diameter), and making it easier to reduce the size of the gear device 1 as a whole. If the dimensions of the planetary gear 3 are constant, for example, it is possible to increase the number (number) of inner pins 4 to smooth the transmission of rotation, or to thicken the inner pins 4 to improve strength. Furthermore, the number of parts can be reduced by the amount of the inner roller, which also leads to a reduction in the cost of the gear device 1.

The retaining member 55 is fixed to the hub member 14, which is a fixed member. As a result, the planetary gear 3 is connected to the fixed member (hub member 14) via the retaining member 55 by the multiple inner pins 4. Since the retaining member 55 is fixed to the hub member 14 in this way, the retaining member 55 may also be included in the "fixed member". As a result, the multiple inner pins 4 are held directly or indirectly by the fixed member, so that their relative positions with respect to the rotation axis Ax1 are fixed. Furthermore, the opening surface of the retaining hole 551 on the input side of the rotation axis Ax1 is closed by, for example, the hub member 14. As a result, the movement of the inner pins 4 toward the input side of the rotation axis Ax1 is restricted by the hub member 14.

The holding member 55 has a bearing hole 552 in the center in a plan view that penetrates the holding member 55 in the direction of the rotation axis Ax1. The bearing hole 552 is a hole for passing the eccentric shaft 54 and communicates with the through hole 142 of the hub member 14. The holding member 55 and the eccentric shaft 54 are configured to be relatively rotatable around the rotation axis Ax1. Specifically, the inner diameter of the holding member 55 (the diameter of the bearing hole 552) is larger than the outer diameter of the eccentric shaft 54 (the shaft center portion 541), and when the eccentric shaft 54 is inserted into the bearing hole 552, a gap is generated between the holding member 55 and the eccentric shaft 54.

Here, the first inner ring 61 of the first bearing member 6 and the second inner ring 71 of the second bearing member 7 are fixed to the holding member 55. In this embodiment, as an example, the first inner ring 61 is integrated with the holding member 55. Specifically, the first inner ring 61 has a flange shape that protrudes from the outer circumferential surface 553 of the holding member 55 at the end of the output side of the rotation shaft Ax1 in the holding member 55 over the entire circumference. In particular, in this embodiment, the holding member 55 and the first inner ring 61 are integrally formed from a single metal member, and as a result, the holding member 55 and the first inner ring 61 are treated as a seamless single part.

The first bearing member 6 is a component that rotatably supports the multiple inner pins 4 relative to the gear body 22. In other words, the first bearing member 6 is a component that rotatably supports a rotating member (such as the body portion 11) relative to a fixed member (such as the hub member 14).

The second bearing member 7 is a component that rotatably supports the multiple inner pins 4 relative to the gear body 22. In other words, the second bearing member 7, together with the first bearing member 6, is a component that rotatably supports a rotating member (such as the body portion 11) relative to a fixed member (such as the hub member 14).

The first bearing member 6 and the second bearing member 7 are arranged in the direction of the rotation axis Ax1, and support the multiple inner pins 4 rotatably relative to the gear body 22 at two points in the direction of the rotation axis Ax1. In this embodiment, the first inner ring 61 and the second inner ring 71 are fixed to a fixed member (hub member 14, etc.), and the first outer ring 62 and the second outer ring 72 are fixed to a rotating member (body part 11, etc.). Therefore, the first bearing member 6 and the second bearing member 7 both support the rotating member (body part 11, etc.) rotatably relative to the fixed member (hub member 14, etc.) by the inner ring and the outer ring being rotatable relative to each other. The first bearing member 6 and the second bearing member 7 will be described in more detail in the section "(3.2) Bearing Members".

As shown in FIG. 2, the eccentric shaft 54 is a cylindrical part. The eccentric shaft 54 has an axial center portion 541 and an eccentric portion 542. The axial center portion 541 has a cylindrical shape with at least the outer circumferential surface being a perfect circle in a plan view. The center (central axis) of the axial center portion 541 coincides with the rotation axis Ax1. The eccentric portion 542 has a disk shape with at least the outer circumferential surface being a perfect circle in a plan view. The center (central axis) of the eccentric portion 542 coincides with the center C1 shifted from the rotation axis Ax1. Here, the distance ΔL (see FIG. 2) between the rotation axis Ax1 and the center C1 is the eccentricity of the eccentric portion 542 with respect to the axial center portion 541. The eccentric portion 542 has a flange shape that protrudes from the outer circumferential surface of the axial center portion 541 over the entire circumference, except for both ends of the axial center portion 541 in the longitudinal direction (axial direction). According to the above-described configuration, the eccentric shaft 54 rotates (spins) the axial center portion 541 about the rotation axis Ax1, causing the eccentric portion 542 to perform eccentric motion.

In this embodiment, the shaft center portion 541 and the eccentric portion 542 are integrally formed from a single metal member, thereby realizing a seamless eccentric shaft 54. The eccentric shaft 54 having this shape is combined with the planetary gear 3 together with the eccentric body bearing 5. Therefore, when the eccentric shaft 54 rotates with the eccentric body bearing 5 and the eccentric shaft 54 combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51, and is a component that absorbs the rotation component of the rotation of the eccentric shaft 54 and transmits only the rotation of the eccentric shaft 54 excluding the rotation component of the eccentric shaft 54, that is, only the oscillation component (revolution component) of the eccentric shaft 54, to the planetary gear 3. In addition to the eccentric outer ring 52 and the eccentric inner ring 51, the eccentric bearing 5 has multiple rolling elements 53 (see Figure 4).

The eccentric outer ring 52 and the eccentric inner ring 51 are both annular parts. The eccentric outer ring 52 and the eccentric inner ring 51 both have an annular shape that is a perfect circle in a plan view. The eccentric inner ring 51 is one size smaller than the eccentric outer ring 52 and is disposed inside the eccentric outer ring 52. Here, since the inner diameter of the eccentric outer ring 52 is larger than the outer diameter of the eccentric inner ring 51, a gap is generated between the inner peripheral surface of the eccentric outer ring 52 and the outer peripheral surface of the eccentric inner ring 51.

The multiple rolling elements 53 are arranged in the gap between the eccentric outer ring 52 and the eccentric inner ring 51. The multiple rolling elements 53 are arranged in a line in the circumferential direction of the eccentric outer ring 52. The multiple rolling elements 53 are all metal parts of the same shape, and are provided at equal pitches over the entire circumferential area of the eccentric outer ring 52. In this embodiment, as an example, the eccentric bearing 5 is a deep groove ball bearing that uses spheres (balls) as the rolling elements 53.

Here, the inner diameter of the eccentric inner ring 51 is equal to the outer diameter of the eccentric portion 542 of the eccentric shaft 54. The eccentric bearing 5 is assembled with the eccentric shaft 54 in a state where the eccentric portion 542 of the eccentric shaft 54 is inserted into the eccentric inner ring 51. The outer diameter of the eccentric outer ring 52 is equal to the inner diameter (diameter) of the opening 33 of the planetary gear 3. The eccentric bearing 5 is assembled with the planetary gear 3 in a state where the eccentric outer ring 52 is fitted into the opening 33 of the planetary gear 3. In other words, the opening 33 of the planetary gear 3 accommodates the eccentric bearing 5 attached to the eccentric portion 542 of the eccentric shaft 54.

In addition, in this embodiment, as an example, the widthwise dimensions (direction parallel to the rotation axis Ax1) of the eccentric inner ring 51 and the eccentric outer ring 52 in the eccentric bearing 5 are both approximately the same as the thickness of the eccentric portion 542 of the eccentric shaft 54. Furthermore, the widthwise dimensions of the eccentric inner ring 51 and the eccentric outer ring 52 are greater than the thickness of the planetary gear 3. Therefore, in the direction parallel to the rotation axis Ax1, the planetary gear 3 fits within the range of the eccentric bearing 5.

When the eccentric shaft 54 rotates with the eccentric bearing 5 and the eccentric shaft 54 combined with the planetary gear 3, the eccentric inner ring 51 rotates (eccentrically moves) around the rotation axis Ax1 that is offset from the center C1 of the eccentric inner ring 51 in the eccentric bearing 5. At this time, the rotation component of the eccentric shaft 54 is absorbed by the eccentric bearing 5. Therefore, the rotation of the eccentric shaft 54 excluding the rotation component of the eccentric shaft 54, that is, only the oscillation component (revolution component) of the eccentric shaft 54 is transmitted to the planetary gear 3 by the eccentric bearing 5. Therefore, when the eccentric shaft 54 rotates with the eccentric bearing 5 and the eccentric shaft 54 combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

2, the support 8 is a part that is formed in an annular shape and supports the multiple inner pins 4. The support 8 has an annular shape in which at least the outer peripheral surface 81 is a perfect circle in a plan view. The support 8 has multiple support holes 82 into which the multiple inner pins 4 are respectively inserted. The support holes 82 are provided in the same number as the inner pins 4, and in the present embodiment, as an example, eight support holes 82 are provided. Each of the multiple support holes 82 opens in a circular shape and is a hole that penetrates the support 8 along the thickness direction. The multiple (here, eight) support holes 82 are arranged at equal intervals in the circumferential direction on a virtual circle that is concentric with the outer peripheral surface 81 of the support 8. The diameter of the support hole 82 is equal to or greater than the diameter of the inner pin 4 and is smaller than the diameter of the loose fitting hole 32. In the present embodiment, as an example, the diameter of the support hole 82 is equal to the diameter of the holding hole 551 formed in the holding member 55. Therefore, the support 8 supports the multiple inner pins 4 in a state in which each of the multiple inner pins 4 can rotate on its own axis. In other words, each of the multiple inner pins 4 is held in a rotatable state relative to both the holding member 55 and the support body 8.

As shown in FIG. 3, the support 8 is disposed so as to face the planetary gear 3 from one side (output side) of the rotation axis Ax1. Then, by inserting the multiple inner pins 4 into the multiple support holes 82, the support 8 functions to bundle the multiple inner pins 4. In this way, the support 8 distributes the load acting on the multiple inner pins 4 when transmitting the rotation (rotation component) of the planetary gear 3 to a fixed member or a rotating member.

Furthermore, the support 8 is positionally restricted by contacting its outer peripheral surface 81 with the multiple outer pins 23. Here, the diameter of the outer peripheral surface 81 of the support 8 is the same as the diameter of an imaginary circle (tooth tip circle) passing through the tips of the internal teeth 21 of the internal gear 2. Therefore, all of the multiple outer pins 23 are in contact with the outer peripheral surface 81 of the support 8. Therefore, when the support 8 is positionally restricted by the multiple outer pins 23, the center of the support 8 is positionally restricted so as to overlap with the center (rotation axis Ax1) of the internal gear 2. This allows the support 8 to be centered, and as a result, the multiple inner pins 4 supported by the support 8 are also centered by the multiple outer pins 23.

The multiple outer pins 23 also form the internal teeth 21 of the internal gear 2. Therefore, when the gear body 22 and the multiple inner pins 4 rotate relative to each other, the support 8 supporting the multiple inner pins 4 rotates relative to the internal gear 2 (gear body 22) together with the multiple inner pins 4. At this time, since the support 8 is centered by the multiple outer pins 23, the support 8 rotates smoothly relative to the internal gear 2 while the center of the support 8 is maintained on the rotation axis Ax1. Moreover, the outer peripheral surface 81 of the support 8 rotates relative to the gear body 22 together with the multiple inner pins 4 while in contact with the multiple outer pins 23. Therefore, if the gear body 22 of the internal gear 2 is considered to be the "outer ring" and the support 8 is considered to be the "inner ring", the multiple outer pins 23 interposed between them function as "rolling bodies (rollers)". In this way, the support 8, together with the internal gear 2 (gear body 22 and multiple outer pins 23), constitutes a needle bearing (needle roller bearing), enabling smooth rotation.

Furthermore, since the support 8 sandwiches the outer pins 23 between itself and the gear body 22, the support 8 also functions as a "stopper" that suppresses movement of the outer pins 23 away from the inner circumferential surface 221 of the gear body 22. In other words, the outer pins 23 are sandwiched between the outer circumferential surface 81 of the support 8 and the inner circumferential surface 221 of the gear body 22, suppressing lifting of the outer pins 23 from the inner circumferential surface 221 of the gear body 22. In short, in this embodiment, each of the outer pins 23 comes into contact with the outer circumferential surface 81 of the support 8, thereby restricting movement away from the gear body 22.

In addition, in this embodiment, as shown in FIG. 3, the support 8 is located on the opposite side of the planetary gear 3 from the holding member 55. In other words, the support 8, planetary gear 3, and holding member 55 are arranged in a direction parallel to the rotation axis Ax1. The support 8, together with the holding member 55, supports both ends of the inner pin 4 in the longitudinal direction (direction parallel to the rotation axis Ax1), and the central portion of the inner pin 4 in the longitudinal direction is inserted into the loose fitting hole 32 of the planetary gear 3. In this way, the support 8 and the holding member 55 support both ends of the inner pin 4 in the longitudinal direction, so that the inner pin 4 is less likely to tilt. In particular, it is also more likely to receive bending forces (bending moment loads) with respect to the rotation axis Ax1 that are applied to the multiple inner pins 4.

In addition, in this embodiment, the support 8 is sandwiched between the planetary gear 3 and the case 10 (cap 12) in a direction parallel to the rotation axis Ax1. As a result, the movement of the support 8 toward the output side of the rotation axis Ax1 (left side in FIG. 9) is restricted by the case 10. The movement of the inner pin 4, which penetrates the support hole 82 of the support 8 and protrudes from the support 8 toward the output side of the rotation axis Ax1, toward the output side of the rotation axis Ax1 is also restricted by the case 10.

The first bearing 91 and the second bearing 92 are each mounted on the axial center portion 541 of the eccentric shaft 54. Specifically, as shown in FIG. 3, the first bearing 91 and the second bearing 92 are mounted on both sides of the eccentric portion 542 in the axial center portion 541 so as to sandwich the eccentric portion 542 in a direction parallel to the rotation axis Ax1. The first bearing 91 is disposed on the output side of the rotation axis Ax1 as viewed from the eccentric portion 542. The second bearing 92 is disposed on the input side of the rotation axis Ax1 as viewed from the eccentric portion 542. In this embodiment, as an example, both the first bearing 91 and the second bearing 92 are deep groove ball bearings that use spheres (balls) as rolling elements.

The first bearing 91 is held by the case 10. Specifically, a circular recess is formed on the input side surface of the rotation axis Ax1 in the cap 12, and the first bearing 91 is fitted into this recess to attach the first bearing 91 to the case 10. On the other hand, the second bearing 92 is held by the holding member 55. Specifically, the second bearing 92 is fitted into a bearing hole 552 in the holding member 55 to attach the second bearing 92 to the holding member 55. In other words, the second bearing 92 is mounted in the gap between the holding member 55 and the eccentric shaft 54. As a result, the shaft center portion 541 of the eccentric shaft 54 is rotatably held at two points on both sides of the eccentric portion 542 in the direction parallel to the rotation axis Ax1.

The balance weight 56 is a part through which the axial center portion 541 of the eccentric shaft 54 is inserted. Here, as in the gear device 1 according to the present embodiment, when the input rotation on the high-speed rotation side is accompanied by eccentric motion, if the weight balance of the rotating body rotating at high speed is not achieved, it may lead to vibrations and the like. Therefore, the balance weight is provided to achieve weight balance with respect to the rotation axis Ax1 of the rotating body consisting of at least one of the eccentric inner ring 51 and the member (eccentric shaft 54) that rotates with the eccentric inner ring 51. The balance weight 56 is formed asymmetrically with respect to the rotation axis Ax1, and in the present embodiment, as an example, is formed in a substantially fan shape. Here, the balance weight 56 acts to bring the weight balance of the eccentric shaft 54 closer to equality in the circumferential direction from the rotation axis Ax1 by adding weight to the opposite side of the center C1 of the eccentric outer ring 52 as viewed from the rotation axis Ax1.

The spacer 93 is a part through which the axial center portion 541 of the eccentric shaft 54 is inserted. The spacer 93 is an annular part, and is disposed between the eccentric portion 542 of the eccentric shaft 54 and the first bearing 91. This ensures a gap of the size of the spacer 93 between the eccentric portion 542 and the first bearing 91.

As shown in FIG. 3, the gear device 1 according to this embodiment further includes a plurality of oil seals 94, 95, 96, etc. The oil seal 94 is attached between the hub member 14 and the ring cap 13, and closes the gap between the hub member 14 and the ring cap 13. The oil seals 95, 96 are attached to the axial center portion 541 of the eccentric shaft 54 and are disposed in the through hole 142 of the hub member 14, thereby closing the gap between the hub member 14 and the eccentric shaft 54. The internal space of the case 10, sealed by the plurality of oil seals 94, 95, 96, constitutes an airtight space.

Then, a lubricant is injected into the sealed space (the internal space of the case 10). The lubricant is liquid and can flow in the sealed space. Therefore, when the gear device 1 is used, for example, the lubricant enters the meshing portion between the internal teeth 21 consisting of the multiple outer pins 23 and the external teeth 31 of the planetary gear 3. The "liquid" in this disclosure includes liquid or gel-like substances. The "gel-like" here means a state having intermediate properties between liquid and solid, and includes a colloidal state consisting of two phases, a liquid phase and a solid phase. For example, the "gel-like" includes a state called a gel or sol, such as an emulsion in which the dispersion medium is in a liquid phase and the dispersoid is in a liquid phase, and a suspension in which the dispersoid is in a solid phase. The "gel-like" also includes a state in which the dispersion medium is in a solid phase and the dispersoid is in a liquid phase. In this embodiment, as an example, the lubricant is a liquid lubricating oil (oil).

In the gear device 1 having the above-described configuration, a rotational force is applied as an input to the eccentric shaft 54, and the eccentric shaft 54 rotates around the rotation axis Ax1, causing the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and oscillates with a part of the external teeth 31 meshed with a part of the internal teeth 21, so that the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. As a result, a relative rotation according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). The planetary gear 3 is connected to a fixed member (such as the hub member 14) by a plurality of internal pins 4, and the gear body 22 is fixed to a rotating member (such as the body 11), so that the relative rotation between the planetary gear 3 and the internal gear 2 is taken out from the internal gear 2. At this time, only the rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is extracted from the internal gear 2. As a result, the rotating member to which the gear body 22 is fixed produces a rotation output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

As described above, in the gear device 1 according to this embodiment, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 determines the reduction ratio of the output rotation to the input rotation in the gear device 1. In other words, if the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2," the reduction ratio R1 is expressed by the following formula 1. However, here, the relative rotation between the planetary gear 3 and the internal gear 2 is assumed to be a case in which the gear body 22 is fixed to a rotating member and taken out from the internal gear 2.

R1=V1/(V1-V2)...(Formula 1)
In short, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3, the larger the reduction ratio R1. As an example, the number of teeth V1 of the internal gear 2 is "30", the number of teeth V2 of the planetary gear 3 is "29", and the difference in the number of teeth (V1-V2) is "1", so from the above formula 1, the reduction ratio R1 is "30". In this case, when viewed from the input side of the rotation axis Ax1, when the eccentric shaft 54 rotates one revolution (360 degrees) clockwise around the rotation axis Ax1, the gear main body 22 rotates clockwise around the rotation axis Ax1 by the difference in the number of teeth of "1" (i.e., approximately 12.0 degrees).

With the gear device 1 according to this embodiment, such a high reduction ratio R1 can be achieved with a combination of one gear stage (internal gear 2 and planetary gear 3).

The gear device 1 must include at least an internal gear 2, a planetary gear 3, a plurality of internal pins 4, a first bearing member 6, and a second bearing member 7, and may further include other components such as a spline bush.

(3.2) Bearing Members Next, the configurations of the first bearing member 6 and the second bearing member 7 according to this embodiment will be described in more detail.

As shown in Figs. 2 and 3, the first bearing member 6 has a first inner ring 61 and a first outer ring 62. The first inner ring 61 and the first outer ring 62 are in a relatively rotatable relationship around the rotation axis Ax1. As shown in Figs. 2 and 3, the first bearing member 6 has a plurality of bearing pins 63 in addition to the first outer ring 62 and the first inner ring 61.

As shown in Figures 7 to 9, the first inner ring 61 and the first outer ring 62 are both annular components. The first inner ring 61 and the first outer ring 62 each have an annular shape that is a perfect circle centered on the rotation axis Ax1 in a plan view. The first inner ring 61 is one size smaller than the first outer ring 62 and is disposed inside the first outer ring 62. Here, since the inner diameter of the first outer ring 62 is larger than the outer diameter of the first inner ring 61, a gap is generated between the inner circumferential surface 621 of the first outer ring 62 and the outer circumferential surface 611 of the first inner ring 61 (see Figure 7).

As described above, the first inner ring 61 is fixed to the retaining member 55. The outer peripheral surface 611 of the first inner ring 61 is formed concentrically with the outer peripheral surface 553 of the retaining member 55 in a plan view. In this embodiment, the first inner ring 61 is integrated with the retaining member 55, and the flange-shaped portion protruding from the outer peripheral surface 553 of the retaining member 55 over the entire circumference constitutes the first inner ring 61. In other words, in FIG. 7, the outer portion of the outer peripheral surface 553 shown by the imaginary line (two-dot chain line) corresponds to the first inner ring 61. Since the retaining member 55 is fixed to the hub member 14, the first inner ring 61 is consequently fixed to the fixed member (hub member 14, etc.).

As described above, the first outer ring 62 is fixed to the body 11, which is a rotating member. The inner circumferential surface 621 of the first outer ring 62 is formed concentrically with the outer circumferential surface 611 of the first inner ring 61 in a plan view. In this embodiment in particular, the first outer ring 62 is integrated with the body 11, and a part of the body 11 constitutes the first outer ring 62.

The multiple bearing pins 63 are arranged between the first inner ring 61 and the first outer ring 62. The multiple bearing pins 63 are arranged in a line in the circumferential direction of the first outer ring 62. The multiple bearing pins 63 are all metal parts of the same shape, and are provided at equal pitches over the entire circumferential area of the first outer ring 62. Each of the multiple bearing pins 63 is formed in a cylindrical shape. The diameter and length of the multiple bearing pins 63 are common to all of the multiple bearing pins 63.

Here, the multiple bearing pins 63 are held between the first inner ring 61 and the first outer ring 62 in a rotatable state. The multiple bearing pins 63 are sandwiched between the outer peripheral surface 611 of the first inner ring 61 and the inner peripheral surface 621 of the first outer ring 62, so that when the first outer ring 62 rotates relative to the first inner ring 61, each of the multiple bearing pins 63 rotates (rotates) in conjunction with the rotation of the first outer ring 62. Thus, the first bearing member 6 constitutes a needle bearing (needle roller bearing).

In this embodiment, the multiple bearing pins 63 are held on the inner circumferential surface 621 of the first outer ring 62 in a rotatable state. Specifically, as shown in FIG. 9, multiple grooves are formed on the inner circumferential surface 621 of the first outer ring 62 over the entire circumferential direction. These multiple grooves are multiple bearing grooves 622 (see FIG. 7) as a holding structure for the multiple bearing pins 63. In other words, the holding structure for the multiple bearing pins 63 includes multiple bearing grooves 622 formed on the inner circumferential surface 621 of the first outer ring 62. The multiple bearing grooves 622 are all of the same shape and are provided at equal pitches. All of the multiple bearing grooves 622 are parallel to the rotation axis Ax1 and are formed over the entire width of the gear body 22.

However, in this embodiment, since the first outer ring 62 is part of the body 11 as described above, the multiple bearing grooves 622 are formed only in the portion of the body 11 that corresponds to the first outer ring 62 (see FIG. 10). The multiple bearing pins 63 are assembled to the first outer ring 62 (body 11) so as to fit into the multiple bearing grooves 622. Each of the multiple bearing pins 63 is held in a rotatable state within the bearing groove 622, and the circumferential movement of the first outer ring 62 is restricted by the bearing groove 622.

As described above, because the first bearing member 6 is a needle bearing, the first bearing member 6 is more likely to receive loads mainly in the radial direction. Needle bearings have a higher radial load capacity than deep groove ball bearings and the like, so by providing such a first bearing member 6, the radial load capacity (load capacity) of the gear device 1 as a whole can be increased.

That is, the first bearing member 6 uses, as rolling elements, a plurality of outer pins 23 that form the internal teeth 21 of the internal gear 2, and a plurality of bearing pins 63 that basically have the same configuration. In particular, in this embodiment, the bearing pins 63 and the outer pins 23 are the same in number and diameter. That is, as shown in Figures 4 and 7, there are 30 outer pins 23 and 30 bearing pins 63, and the diameter φ1 of the outer pins 23 (see Figure 4) and the diameter φ2 of the bearing pins 63 (see Figure 7) are the same (φ1 = φ2).

Furthermore, the outer pin 23 and the bearing pin 63 are arranged in the same manner when viewed from one side in the direction of the rotation axis Ax1. Therefore, in a direction parallel to the rotation axis Ax1, the outer pin 23 and the bearing pin 63 are arranged so as to overlap each other. Specifically, the multiple gear grooves 222 as a holding structure for the multiple outer pins 23 formed on the inner circumferential surface 221 of the gear body 22 and the multiple bearing grooves 622 as a holding structure for the multiple bearing pins 63 formed on the inner circumferential surface 621 of the first outer ring 62 adopt a common arrangement. In other words, the multiple gear grooves 222 and the multiple bearing grooves 622 are both formed in the gear body 22 or the first outer ring 62, which are part of the trunk 11, and are arranged in the same manner when viewed from one side in the direction of the rotation axis Ax1 (see FIG. 2). As a result, the outer pin 23 held in the gear groove 222 and the bearing pin 63 held in the bearing groove 622 have the same arrangement when viewed from one side in the direction of the rotation axis Ax1.

However, the gear groove 222 as the holding structure of the outer pin 23 and the bearing groove 622 as the holding structure of the bearing pin 63 have different shapes. In this embodiment, the depth D1 of the gear groove 222 (see FIG. 4) is greater than the depth D2 of the bearing groove 622 (see FIG. 7). In other words, the depths of the multiple gear grooves 222 and the multiple bearing grooves 622 are different (D1>D2). Specifically, the gear groove 222 and the bearing groove 622 are grooves having an arc-shaped bottom surface with a diameter equal to or greater than the diameter φ1 (=φ2) of the outer pin 23 or the bearing pin 63 when viewed from one side of the rotation axis Ax1 direction. In other words, the bottom surfaces of the gear groove 222 and the bearing groove 622 have a radius of curvature equal to or greater than the radius of the outer pin 23 or the bearing pin 63. As an example, the bottom surfaces of the gear groove 222 and the bearing groove 622 both have the same radius of curvature as the radius of the outer pin 23 or the bearing pin 63. The bearing groove 622 is configured to be shallower than the gear groove 222.

In this embodiment, the diameter φ1 of the outer pin 23 and the diameter φ2 of the bearing pin 63 are the same (φ1 = φ2), so the ratio of the depth to the diameter of the pin held by the bearing grooves 622 is smaller than that of the gear grooves 222. In other words, the ratio (D2/φ2) of the depth D2 to the diameter φ2 of the bearing pin 63 in the bearing groove 622 is smaller than the ratio (D1/φ1) of the depth D1 to the diameter φ1 of the outer pin 23 in the gear groove 222. In this embodiment, as an example, the ratio (D1/φ1) of the depth D1 of the gear groove 222 to the diameter φ1 of the outer pin 23 is "1/2". On the other hand, the ratio (D2/φ2) of the depth D2 of the bearing groove 622 to the diameter φ2 of the bearing pin 63 is "1/3". Here, the ratio (D2/φ2) of the depth D2 of the bearing groove 622 to the diameter φ2 of the bearing pin 63 is preferably 1/2 or less, more preferably 1/3 or less, and may be, for example, about 1/4.

In short, since the outer pin 23 is mainly subjected to a force in the rotational direction about the rotation axis Ax1, while the bearing pin 63 is mainly subjected to a force in the radial direction, the bearing groove 622 that holds the bearing pin 63 only needs to have a minimum depth D2 that prevents the bearing pin 63 from falling off. In fact, by keeping the depth D2 of the bearing groove 622 small, there is an advantage in that the frictional resistance between the inner surface of the bearing groove 622 and the bearing pin 63 can be reduced, thereby reducing losses in the first bearing member 6. Furthermore, by keeping the depth D2 of the bearing groove 622 small, there is also an advantage in that the lubricant can easily enter the bearing groove 622.

As described above, in this embodiment, the outer pin 23 and the bearing pin 63 have the same diameter and are arranged in the same manner when viewed from one side in the direction of the rotation axis Ax1. Therefore, in this embodiment, the central axis Ax2 (see FIG. 10) about which the outer pin 23 rotates (spins) and the central axis Ax3 (see FIG. 10) about which the bearing pin 63 rotates (spins) are located on a straight line. In other words, each of the multiple bearing pins 63 is arranged concentrically with each of the multiple outer pins 23.

In addition, in this embodiment, each of the multiple bearing pins 63 is separate from each of the multiple outer pins 23. The rotation (rotation) of the outer pin 23 and the rotation (rotation) of the bearing pin 63 are asynchronous to begin with, but the outer pin 23 and the bearing pin 63, which are configured as separate bodies, can rotate individually. In other words, the rotation (rotation) of the outer pin 23 and the rotation (rotation) of the bearing pin 63 are unlikely to interfere with each other and are unlikely to hinder each other's rotation. However, the outer pin 23 and the bearing pin 63 may rotate partially synchronously.

In addition, in this embodiment, the outer peripheral surface 611 of the first inner ring 61 has a smaller surface roughness than one surface adjacent to the outer peripheral surface 611 of the first inner ring 61. In other words, the surface roughness of the outer peripheral surface 611 is smaller than both end surfaces of the first inner ring 61 in the direction of the rotation axis Ax1. In this disclosure, "surface roughness" means the degree of roughness of the surface of an object, and the smaller the value, the smaller (fewer) the surface irregularities are, and the smoother the surface is. In this embodiment, as an example, the surface roughness is the arithmetic mean roughness (Ra). For example, by a process such as polishing, the outer peripheral surface 611 of the first inner ring 61 has a smaller surface roughness than surfaces other than the outer peripheral surface 611 of the first inner ring 61. In this configuration, the rotation of the first outer ring 62 relative to the first inner ring 61 becomes smoother.

In this embodiment, the hardness of the outer peripheral surface 611 of the first inner ring 61 is lower than that of the peripheral surfaces of the multiple bearing pins 63 and higher than that of the inner peripheral surface 621 of the first outer ring 62. In this disclosure, "hardness" means the degree of hardness of an object, and the hardness of a metal is expressed, for example, by the size of a depression made by pressing a steel ball with a certain pressure. Specifically, examples of metal hardness include Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), and Shore hardness (Hs). Means for increasing (hardening) the hardness of metal parts include, for example, alloying or heat treatment. In this embodiment, as an example, the hardness of the outer peripheral surface 611 of the first inner ring 61 is increased by a process such as carburizing and quenching. In this configuration, wear powder and the like are less likely to be generated even when the first outer ring 62 rotates relative to the first inner ring 61, and it is easy to maintain smooth rotation of the first bearing member 6 for a long period of time.

In this way, it is preferable that a surface configuration with low surface roughness and high hardness is also applied to the outer peripheral surface 81 of the support 8. In other words, in this embodiment, the support 8 functions as the "inner ring" of a needle bearing similar to the first bearing member 6, so it is preferable that an appropriate surface roughness and hardness are also applied to the outer peripheral surface 81 of the support 8, which corresponds to the outer peripheral surface of the inner ring.

As shown in Figs. 2 and 3, the second bearing member 7 has a second outer ring 72 and a second inner ring 71. The second inner ring 71 and the second outer ring 72 are in a relatively rotatable relationship around the rotation axis Ax1. As shown in Figs. 2 and 3, the second bearing member 7 has a plurality of second rolling elements 73 in addition to the second outer ring 72 and the second inner ring 71.

As shown in FIG. 2, the second inner ring 71 and the second outer ring 72 are both annular parts. The second inner ring 71 and the second outer ring 72 each have an annular shape that is a perfect circle centered on the rotation axis Ax1 in a plan view. The second inner ring 71 is one size smaller than the second outer ring 72 and is disposed inside the second outer ring 72. Here, since the inner diameter of the second outer ring 72 is larger than the outer diameter of the second inner ring 71, a gap is generated between the inner peripheral surface of the second outer ring 72 and the outer peripheral surface of the second inner ring 71. Furthermore, in this embodiment, as shown in FIG. 3, the inner diameter of the second outer ring 72 is larger than the outer diameter of the first inner ring 61 and smaller than the inner diameter of the first outer ring 62. The outer diameter of the second inner ring 71 is smaller than the outer diameter of the first inner ring 61.

The second inner ring 71 is fixed to the retaining member 55. Here, the inner diameter of the second inner ring 71 matches the outer diameter of the retaining member 55 (the outer peripheral surface 553 thereof). The second bearing member 7 is combined with the retaining member 55 with the retaining member 55 inserted into the second inner ring 71. Since the retaining member 55 is fixed to the hub member 14, the second inner ring 71 is consequently fixed to the fixed member (hub member 14, etc.).

The second outer ring 72 is fixed to the body 11, which is a rotating member. The outer diameter of the second outer ring 72 matches the inner diameter of the outer ring fixing frame 74 (see FIG. 3) in the body 11. The second bearing member 7 is combined with the body 11 with the second outer ring 72 fitted into the outer ring fixing frame 74 of the body 11. In other words, the outer ring fixing frame 74 of the body 11, which is a rotating member, accommodates the second bearing member 7, which is attached to the retaining member 55.

The second rolling elements 73 are arranged in the gap between the second inner ring 71 and the second outer ring 72. The second rolling elements 73 are arranged in a line in the circumferential direction of the second outer ring 72. The second rolling elements 73 are all metal parts of the same shape, and are arranged at equal pitches over the entire circumferential area of the second outer ring 72. In this embodiment, as an example, the second bearing member 7 is made of a deep groove ball bearing that uses spheres (balls) as the second rolling elements 73. In other words, the second bearing member 7 includes a deep groove ball bearing.

In this way, because the second bearing member 7 is a deep groove ball bearing, the second bearing member 7 is more likely to receive loads mainly in the thrust direction (direction along the rotation axis Ax1). In other words, the second bearing member 7 receives loads at least along the direction of the rotation axis Ax1. Although deep groove ball bearings have a smaller radial load capacity than needle bearings, they have a larger thrust load capacity. Therefore, by providing such a second bearing member 7, the thrust load capacity (load capacity) of the gear device 1 as a whole can be increased.

In short, the gear device 1 according to this embodiment is more susceptible to radial and thrust loads by providing the first bearing member 6 and the second bearing member 7. In other words, the gear device 1 can receive radial loads by the first bearing member 6 made of a needle bearing, and receive thrust loads by the second bearing member 7 made of a deep groove ball bearing. Furthermore, the gear device 1 supports the multiple inner pins 4 rotatably relative to the gear body 22 at two locations in the direction of the rotation axis Ax1 by the first bearing member 6 and the second bearing member 7. Therefore, the gear device 1 is more susceptible to both bending forces (bending moment loads) relative to the rotation axis Ax1.

In this way, the gear device 1 according to this embodiment can withstand three types of loads, radial load, thrust load, and bending force against the rotation axis Ax1, without using a cross roller bearing, and can ensure the necessary rigidity. Moreover, the first bearing member 6 and the second bearing member 7 share the load, which contributes to extending the life of each of the first bearing member 6 and the second bearing member 7.

Next, the arrangement of the first bearing member 6 and the second bearing member 7, including the relative positional relationship between the first bearing member 6 and the second bearing member 7, will be described with reference to Figures 3 and 10. That is, in this embodiment, the first bearing member 6 and the second bearing member 7 rotatably support multiple inner pins 4 with respect to the gear body 22 at two locations in the direction of the rotation axis Ax1. Therefore, the first bearing member 6 and the second bearing member 7 are arranged side by side in a direction parallel to the rotation axis Ax1.

In this embodiment, as shown in FIG. 3, the internal gear 2, the first bearing member 6, and the second bearing member 7 are arranged in the following order from the output side of the rotation axis Ax1: internal gear 2, first bearing member 6, second bearing member 7. That is, the first bearing member 6 is located between the internal gear 2 and the second bearing member 7 in a direction parallel to the rotation axis Ax1. In other words, the first bearing member 6 is located on the same side of the rotation axis Ax1 as the second bearing member 7 with respect to the multiple outer pins 23. In this embodiment, the first bearing member 6 and the second bearing member 7 are both located on the input side of the rotation axis Ax1 (the right side in FIG. 3) with respect to the multiple outer pins 23.

Furthermore, the multiple bearing pins 63 are located between the second bearing member 7 and the multiple outer pins 23 in the direction of the rotation axis Ax1. In other words, the first bearing member 6 is located on the input side of the rotation axis Ax1 (right side in FIG. 3) relative to the multiple outer pins 23, and the second bearing member 7 is located on the input side of the rotation axis Ax1 (right side in FIG. 3) relative to the first bearing member 6. Therefore, the multiple bearing pins 63 of the first bearing member 6 are sandwiched between the second bearing member 7 and the multiple outer pins 23 in the direction parallel to the rotation axis Ax1.

Here, the internal gear 2, the first bearing member 6, and the second bearing member 7 are arranged with almost no gaps in the direction parallel to the rotation axis Ax1. Specifically, as shown in FIG. 10, when the body 11 is divided into three regions in the direction parallel to the rotation axis Ax1, these three regions function as the internal gear 2, the first outer ring 62 of the first bearing member 6, and the outer ring fixing frame 74 for fixing the second bearing member 7, respectively. That is, in this embodiment, the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 constitute a seamless single part (body 11), so in FIG. 10, the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 are divided by the boundary line shown by the imaginary line (two-dot chain line).

With the above-mentioned arrangement, one end of the bearing pins 63 in the direction of the rotation axis Ax1 contacts the second outer ring 72 or the second inner ring 71. Specifically, as shown in FIG. 10, the end face of the bearing pin 63 on the input side of the rotation axis Ax1 (right side in FIG. 10) contacts the second outer ring 72 of the second bearing member 7. As a result, the movement of the bearing pin 63 toward the input side of the rotation axis Ax1 is restricted by the second outer ring 72. Furthermore, the other end of the bearing pins 63 in the direction of the rotation axis Ax1 contacts the outer pin 23. Specifically, as shown in FIG. 10, the end face of the bearing pin 63 on the output side of the rotation axis Ax1 (left side in FIG. 10) contacts the outer pin 23. As a result, the movement of the bearing pin 63 toward the output side of the rotation axis Ax1 is restricted by the outer pin 23.

In addition, in the gear device 1 according to this embodiment, at least a portion of each of the multiple inner pins 4 is disposed in the same position as the first bearing member 6 and the second bearing member 7 in the axial direction of the first bearing member 6 (the direction of the rotation axis Ax1). In other words, as shown in FIG. 10, at least a portion of the inner pin 4 is disposed in the same position as the first bearing member 6 and the second bearing member 7 in the direction parallel to the rotation axis Ax1.

In other words, at least a portion of each of the multiple inner pins 4 is disposed inside the first bearing member 6 and the second bearing member 7. In short, in this embodiment, as described above, the multiple inner pins 4 are located inside the second bearing member 7 when viewed from one side in the direction of the rotation axis Ax1. Furthermore, the multiple inner pins 4 are also located inside the first bearing member 6 when viewed from one side in the direction of the rotation axis Ax1 in relation to the first bearing member 6. In this way, by disposing at least a portion of each of the multiple inner pins 4 at the same position as the first bearing member 6 and the second bearing member 7 in the axial direction of the first bearing member 6, the dimensions of the gear device 1 in the direction parallel to the rotation axis Ax1 can be kept small.

The first bearing member 6 and the second bearing member 7 have the following positional relationship with the retaining member 55 that retains the multiple inner pins 4. That is, the first bearing member 6 and the second bearing member 7 are located outside the retaining member 55 when viewed from one side in the direction of the rotation axis Ax1. Specifically, the first inner ring 61 of the first bearing member 6 has a flange shape that protrudes from the outer circumferential surface 553 of the retaining member 55 over its entire circumference, and is therefore located outside the retaining member 55 when viewed from one side in the direction of the rotation axis Ax1. The second bearing member 7 is combined with the retaining member 55 with the retaining member 55 inserted into the second inner ring 71, and is therefore located outside the retaining member 55 when viewed from one side in the direction of the rotation axis Ax1.

(4) Application Examples Next, application examples of the gear device 1 according to this embodiment will be described with reference to FIG.

The gear device 1 according to this embodiment, together with the wheel body 102, constitutes the wheel device W1. In other words, the wheel device W1 according to this embodiment includes the gear device 1 and the wheel body 102. The wheel body 102 rolls on the running surface due to the rotation output generated when the multiple inner pins 4 rotate relative to the gear body 22. In this embodiment, the body 11, cap 12, and ring cap 13, which are "rotating members" of the case 10 that constitutes the outer shell of the gear device 1, constitute the wheel body 102. In other words, in the wheel device W1 according to this embodiment, the gear device 1 operates with the rotation of the eccentric shaft 54 as the input rotation and the rotation of the rotating member (body 11, etc.) to which the gear body 22 is fixed as the output rotation, so that the wheel body 102 rotates and rolls on the running surface. Here, a rubber tire 103 is attached to the outer peripheral surface of the body 11, which is the contact surface of the wheel body 102 with the running surface, that is, the ground contact surface.

The wheel device W1 using the gear device 1 constitutes a vehicle V1 together with a vehicle body 100, as shown in FIG. 11, for example. In other words, the vehicle V1 according to this embodiment includes the wheel device W1 and the vehicle body 100. The vehicle body 100 holds the wheel device W1. That is, the vehicle V1 according to this embodiment uses the wheel device W1 including the gear device 1 as a wheel, and the wheel body 102 rotates and rolls on the running surface, thereby running on a flat running surface such as a floor surface. In the example of FIG. 11, the vehicle V1 includes four wheel devices W1, and the wheel devices W1 are attached to the four corners of the vehicle body 100, which is rectangular in plan view. Such a vehicle V1 includes a driving source 101 for applying a driving force to the wheel devices W1. In the example of FIG. 11, the vehicle V1 is equipped with four driving sources 101, and the driving sources 101 adopt an "in-wheel motor" layout that corresponds one-to-one with the wheel devices W1.

The driving source 101 generates a driving force for oscillating the planetary gear 3 of the gear device 1 included in each wheel device W1. Specifically, the driving source 101 is a power generating source such as a motor (electric motor). The power generated by the driving source 101 is transmitted to the eccentric shaft 54 in the gear device 1. In other words, the driving source 101 rotates the eccentric shaft 54 of the corresponding wheel device W1 around the rotation axis Ax1, thereby oscillating the planetary gear 3. As a result, the rotation (input rotation) generated by the driving source 101 is decelerated at a relatively high reduction ratio in the gear device 1, causing the wheel body 102 to rotate with a relatively high torque.

In this way, multiple (here, four) wheel devices W1 are driven individually, allowing the vehicle V1 to move in any direction on the traveling surface. For example, the vehicle V1 travels in a straight line by driving the multiple wheel devices W1 to rotate in the same direction at the same speed, and by providing a rotational difference between the multiple wheel devices W1, the vehicle V1 can change its direction of travel and perform curve driving or turning, etc. Thus, the vehicle V1 can move forward, backward, turn left or right, etc. Turning here includes swivel turns and super swivel turns.

In this way, by using the wheel device W1 as the drive wheel, the vehicle V1 can freely travel on the travel surface by controlling the drive source 101. In particular, the vehicle V1 according to this embodiment is suitable for vehicles that require relatively high torque, such as an automated guided vehicle (AGV). The vehicle V1 as an automated guided vehicle travels autonomously on the travel surface, for example, with an object to be transported loaded on the vehicle body 100. This allows the vehicle V1 to transport an object placed in one location to another location.

In this type of vehicle V1, the wheel device W1 needs to support not only the weight of the vehicle body 100, but also the weight of the transported goods loaded on the vehicle body 100. In other words, not only when the vehicle V1 is moving, but also when the vehicle V1 is stopped, the wheel device W1 may be subjected to a relatively large load in the radial direction (direction perpendicular to the rotation axis Ax1). The wheel device W1 according to this embodiment uses a needle bearing with the bearing pin 63 as a "rolling body (roller)" as the first bearing member 6 of the gear device 1, and therefore can withstand a relatively large load in the radial direction.

When the vehicle V1 curves or turns, the wheel device W1 may also be subjected to a load in the thrust direction (the direction along the rotation axis Ax1), but the load in the thrust direction is sufficiently smaller than the load in the radial direction. Moreover, the wheel device W1 according to this embodiment uses a deep groove ball bearing as the second bearing member 7 of the gear device 1, so that such a load in the thrust direction can be borne by the second bearing member 7. In short, the wheel device W1 using the gear device 1 according to this embodiment is particularly suitable for a vehicle V1, such as an unmanned guided vehicle, which is likely to be subjected to a relatively large load in the radial direction but not so large a load in the thrust direction.

Furthermore, in this embodiment, the gear device 1 extracts the rotational force of the gear body 22 as an output, so when the wheel device W1 is driven, the first outer ring 62 integrated with the gear body 22 also rotates about the rotation axis Ax1. When the first outer ring 62 rotates, the multiple bearing pins 63 held in the multiple bearing grooves 622 of the first outer ring 62 also rotate about the rotation axis Ax1. As a result, in the first bearing member 6 that mainly receives a radial load, the bearing pins 63 located above and below the rotation axis Ax1 change from time to time, making it easier to avoid concentrated loads on some of the bearing pins 63.

In addition, in this embodiment, the driving source 101 is not included in the components of the wheel device W1, but this is not limiting, and the driving source 101 may be included in the components of the wheel device W1. In this case, the wheel device W1 will include the driving source 101, the gear device 1, and the wheel body 102.

(5) Modifications The first embodiment is merely one of various embodiments of the present disclosure. Various modifications of the first embodiment are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, all drawings referred to in this disclosure are schematic drawings, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. Modifications of the first embodiment are listed below. The modifications described below can be applied in appropriate combination.

In the first embodiment, the gear device 1 has one type of planetary gear 3, but the gear device 1 may have multiple planetary gears 3. For example, when the gear device 1 has two planetary gears 3, it is preferable that these two planetary gears 3 are arranged with a phase difference of 180 degrees around the rotation axis Ax1. Also, when the gear device 1 has three planetary gears 3, it is preferable that these three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. In this way, when multiple planetary gears 3 are evenly arranged in the circumferential direction centered on the rotation axis Ax1, it is possible to achieve weight balance between the multiple planetary gears 3.

The tooth profile and other structures (principles) can also be changed as appropriate, and the gear device 1 may be, for example, an eccentric oscillating type gear device that employs a planetary gear 3 with a circulute tooth profile (see JP 2017-137989 A as an example). Furthermore, the gear device 1 may be, for example, an eccentric oscillating type gear device that converts the rotation of an input gear into eccentric oscillation via a spur gear and a crankshaft (see JP 2020-85213 A as an example).

Also, as shown in FIG. 12, each of the multiple bearing pins 63 may be integral with each of the multiple outer pins 23. That is, in the example of FIG. 12, one pin is extended in the axial direction, with one part functioning as the bearing pin 63 and the other part functioning as the outer pin 23. In the configuration of this modified example, the outer pin 23 and the bearing pin 63 rotate together and cannot rotate individually, but it is possible to keep the number of parts to a minimum.

Furthermore, it is not essential for the gear device 1 that each of the multiple inner pins 4 be arranged at the same position as the first bearing member 6 or the second bearing member 7 in the direction of the rotation axis Ax1. In other words, each of the multiple inner pins 4 may be arranged so as to be aligned (opposite) with the first bearing member 6 or the second bearing member 7 in the direction of the rotation axis Ax1.

In addition, the number of inner pins 4, the number of outer pins 23 (the number of teeth of the inner teeth 21), and the number of teeth of the outer teeth 31 described in embodiment 1 are merely examples and can be changed as appropriate.

The second bearing member 7 is not limited to a deep groove ball bearing, and may be, for example, a cross roller bearing or an angular contact ball bearing. Furthermore, the second bearing member 7 may be configured to withstand radial loads, thrust loads (direction along the rotation axis Ax1), and bending forces (bending moment loads) against the rotation axis Ax1, such as a four-point contact ball bearing.

In addition to the second bearing member 7, the gear device 1 may further include a bearing member such as a deep groove ball bearing, a cross roller bearing, or an angular contact ball bearing.

The eccentric bearing 5 is not limited to a deep groove ball bearing, but may be, for example, an angular contact ball bearing. Furthermore, the eccentric bearing 5 is not limited to a ball bearing, but may be, for example, a roller bearing, such as a cylindrical roller bearing, a needle roller bearing, or a tapered roller bearing, in which the rolling elements 53 are not ball-shaped "rollers."

In addition, the material of each component of the gear device 1 is not limited to metal, but may be, for example, a resin such as engineering plastic.

The gear device 1 is not limited to a configuration in which the rotational force of the gear body 22 is extracted as an output when the multiple inner pins 4 rotate relative to the gear body 22. For example, the planetary gear 3 may be connected to a rotating member by the multiple inner pins 4, and the gear body 22 may be fixed to a fixed member, so that the rotational force (rotation component) of the planetary gear 3 can be extracted as an output when the multiple inner pins 4 rotate relative to the gear body 22.

The lubricant is not limited to a liquid substance such as lubricating oil (oil), but may be a gel-like substance such as grease.

The gear device 1 may also include an inner roller. In other words, in the gear device 1, it is not essential that each of the multiple inner pins 4 directly contacts the inner peripheral surface of the loose-fitting hole 32, and an inner roller may be interposed between each of the multiple inner pins 4 and the loose-fitting hole 32. In this case, the inner roller is attached to the inner pin 4 and is rotatable around the inner pin 4 as an axis. Furthermore, it is not essential that each of the multiple inner pins 4 is held in a state in which it can rotate on its own axis relative to the holding member 55.

Furthermore, it is sufficient that at least a portion of each of the multiple inner pins 4 is disposed at the same position as the first bearing member 6 or the second bearing member 7 in the direction of the rotation axis Ax1. For example, each of the multiple inner pins 4 may entirely fall within the range of the first bearing member 6 or the second bearing member 7 in the direction of the rotation axis Ax1.

Furthermore, it is not essential for the gear device 1 that the multiple inner pins 4 connect the planetary gear 3 to a fixed member (such as the hub member 14) via a retaining member 55. For example, the multiple inner pins 4 may be inserted into retaining holes formed in the hub member 14 to directly connect the planetary gear 3 to the fixed member (such as the hub member 14).

In addition, it is not essential for the gear device 1 that the support body 8 positions the multiple inner pins 4 relative to the support body 8 in both the circumferential and radial directions. For example, the support body 8 may have a slit-shaped support hole 82 extending in the radial direction, and position the multiple inner pins 4 relative to the support body 8 only in the circumferential direction. Conversely, the support body 8 may position the multiple inner pins 4 relative to the support body 8 only in the radial direction.

Furthermore, providing the balance weight 56 as in embodiment 1 is not a required configuration for the gear device 1. In other words, instead of adding the balance weight 56, it is possible to reduce the weight of the rotating body (such as the eccentric inner ring 51 and the eccentric shaft 54) by removing some of the material, thereby achieving a weight balance of the rotating body relative to the rotation axis Ax1. With this configuration, it is expected that vibrations and the like caused by the weight balance of the rotating body rotating at high speed can be suppressed while keeping the number of parts to a minimum.

The vehicle V1 may have one or more wheel devices W1, and the number of wheel devices W1 is not limited to four (four wheels). As an example, the vehicle V1 may have one to three wheel devices W1, or may have five or more wheel devices W1. Furthermore, the drive source 101 for driving the wheel devices W1 is not limited to a layout of in-wheel motors that are one-to-one with the wheel devices W1, and one drive source 101 may be provided for multiple wheel devices W1. The wheel devices W1 according to the first embodiment may be provided only on the drive wheels of the vehicle V1, and the vehicle V1 may have one or more driven wheels in addition to the wheel devices W1 as drive wheels. The driven wheels are "non-driven wheels" to which power from the drive source 101 is not transmitted and which do not generate drive force for running the vehicle V1.

The vehicle V1 using the wheel device W1 including the gear device 1 according to the first embodiment is not limited to an automated guided vehicle (AGV), but may be a vehicle other than for transportation purposes, such as a surveillance vehicle or a photography vehicle. Furthermore, the vehicle V1 is not limited to an autonomous vehicle that runs unmanned, but may be, for example, a vehicle operated (driven) by a person, or a vehicle remotely operated by a person.

The gear device 1 according to the first embodiment may be applied to a robot such as a horizontal articulated robot, a so-called SCARA (Selective Compliance Assembly Robot Arm) type robot, without being limited to use as the wheel device W1. In this case, the gear device 1 constitutes an actuator together with a drive source 101 that generates a driving force for oscillating the planetary gear 3, and the actuator is mounted on the robot. Furthermore, application examples of the gear device 1 and the actuator are not limited to horizontal articulated robots, and may be, for example, industrial robots other than horizontal articulated robots, or non-industrial robots. Examples of industrial robots other than horizontal articulated robots include vertical articulated robots and parallel link robots. Examples of non-industrial robots include household robots, nursing care robots, and medical robots.

In addition, it is not essential for the gear device 1 that the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 are integrated together, as in embodiment 1. For example, the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 may be separate bodies (separate parts), and the gear body 22, the first outer ring 62, and the outer ring fixing frame 74 may be fixed to the body 11 by a fixing means such as press fitting, welding, or adhesive.

In addition, it is not essential for the gear device 1 that the first inner ring 61 is integrated with the retaining member 55, as in the first embodiment. For example, the first inner ring 61 and the retaining member 55 may be separate bodies (separate parts), and the first inner ring 61 may be fixed to the retaining member 55 by a fixing means such as press fitting, welding, or adhesive. Furthermore, the second inner ring 71 may be integrated with the retaining member 55.

(Embodiment 2)
As shown in Figures 13 and 14, the internal meshing planetary gear device 1A according to this embodiment (hereinafter also simply referred to as "gear device 1A") differs from the gear device 1 according to embodiment 1 in the configuration of the first bearing member 6A. Hereinafter, configurations similar to those in embodiment 1 will be given the same reference numerals and descriptions thereof will be omitted as appropriate. Figure 13 is a schematic cross-sectional view of the gear device 1A. Figure 14 is a cross-sectional view taken along line B1-B1 in Figure 13 and a partially enlarged view thereof. However, in Figure 14, hatching has been omitted for parts other than the eccentric shaft 54, even in the cross section.

However, in the related art described above, cross roller bearings are used as bearing members, and the relatively complex structure of the cross roller bearings can hinder simplification of the structure of the gear device 1 as a whole. The gear device 1A according to this embodiment has the following configuration, making it possible to provide an internally meshing planetary gear device 1A that is easy to simplify in structure.

That is, the gear device 1A according to this embodiment includes an internal gear 2, a planetary gear 3, a plurality of internal pins 4, and a first bearing member 6A, as shown in Figs. 13 and 14. The internal gear 2 has an annular gear body 22 and a plurality of external pins 23 that are held on the inner peripheral surface 221 of the gear body 22 in a rotatable state and form the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The multiple internal pins 4 rotate relative to the gear body 22 while revolving within the multiple loose fitting holes 32, while being inserted into the multiple loose fitting holes 32 formed in the planetary gear 3. The first bearing member 6A has a first inner ring 61, a first outer ring 62, and a plurality of bearing pins 63. The multiple bearing pins 63 are held between the first inner ring 61 and the first outer ring 62 in a rotatable state. Here, the multiple outer pins 23 and the multiple bearing pins 63 each have a different diameter and a different holding structure.

According to this aspect, the first bearing member 6A has a first inner ring 61, a first outer ring 62, and a plurality of bearing pins 63. In other words, the first bearing member 6A is a needle bearing with the bearing pins 63 as "rolling bodies (rollers)" and can withstand relatively large radial loads. Moreover, the diameters of the outer pins 23 and the bearing pins 63 are different from each other and the holding structures are also different, so depending on the diameter and holding structure of the bearing pins 63, it becomes easier to withstand various expected loads. Therefore, compared to related technologies that use cross roller bearings as bearing members, the gear device 1A according to this embodiment has the advantage that the structure can be simplified.

That is, the diameters of the multiple outer pins 23 and the multiple bearing pins 63 are different. In this embodiment, the ratio of the diameter φ2 (see FIG. 14) to the length of the bearing pin 63 in the first bearing member 6A is larger than in the first embodiment. In other words, in this embodiment, a thick pin is used as the bearing pin 63. Therefore, as shown in FIG. 13, the bearing pin 63 has a thicker diameter than the outer pin 23. In other words, the diameter φ2 of the bearing pin 63 is larger than the diameter φ1 (see FIG. 4) of the outer pin 23. Therefore, in the first bearing member 6A according to this embodiment, the radial load resistance (load capacity) can be increased compared to the first bearing member 6 according to the first embodiment, and the radial load resistance (load capacity) of the gear device 1A as a whole can also be increased.

In this embodiment, the multiple outer pins 23 and the multiple bearing pins 63 have different holding structures. In this disclosure, "different holding structures" means that there is some difference between the holding structure for holding the outer pins 23 and the holding structure for holding the bearing pins 63. As an example, as described in embodiment 1, a case in which the gear groove 222 as the holding structure for the outer pins 23 and the bearing groove 622 as the holding structure for the bearing pins 63 have different shapes (depths) is also included in "different holding structures." As another example, a case in which the multiple outer pins 23 and the multiple bearing pins 63 have different properties such as material or hardness of the holding structure is also included in "different holding structures."

In this embodiment, as in the first embodiment, the depth D1 (see FIG. 4) of the gear groove 222 is greater than the depth D2 (see FIG. 14) of the bearing groove 622. In other words, the depths of the gear grooves 222 and the bearing grooves 622 are different (D1>D2). Specifically, the bearing groove 622 is a groove having an arc-shaped bottom surface with a diameter equal to or greater than the diameter φ2 (>φ1) of the bearing pin 63 when viewed from one side in the direction of the rotation axis Ax1. In other words, the bottom surface of the bearing groove 622 has a larger radius of curvature than the bottom surface of the gear groove 222. Here, as an example, the bottom surface of the bearing groove 622 has the same radius of curvature as the radius of the bearing pin 63. In addition, the bearing groove 622 is configured to be shallower than the gear groove 222.

In this embodiment, although the diameter φ1 of the outer pin 23 is different from the diameter φ2 of the bearing pin 63 (φ1<φ2), the multiple bearing grooves 622 are set to have a smaller ratio of depth to the diameter of the pin they hold, compared to the multiple gear grooves 222. In other words, the ratio (D2/φ2) of the depth D2 to the diameter φ2 of the bearing pin 63 in the bearing groove 622 is smaller than the ratio (D1/φ1) of the depth D1 to the diameter φ1 of the outer pin 23 in the gear groove 222. In this embodiment, as an example, the ratio (D2/φ2) of the depth D2 of the bearing groove 622 to the diameter φ2 of the bearing pin 63 is "1/4" or less.

In short, in this embodiment, the difference between the holding structure for the outer pin 23 (gear groove 222) and the holding structure for the bearing pin 63 (bearing groove 622) is not only the difference in depth (D1 and D2), but also the difference in the radius of curvature of the bottom surface. In this way, when the gear groove 222 and the bearing groove 622 have different shapes, the processing for forming the gear groove 222 and the bearing groove 622 in the body 11 becomes complicated, but the outer pin 23 and the bearing pin 63, which have different diameters, can be reliably held.

In addition, in this embodiment, since the outer pin 23 and the bearing pin 63 have different diameters, the central axis Ax2 about which the outer pin 23 rotates (spins) and the central axis Ax3 about which the bearing pin 63 rotates (spins) are positioned offset from each other. In other words, each of the multiple bearing pins 63 is not positioned concentrically with each of the multiple outer pins 23. In this embodiment, as shown in FIG. 13, the central axis Ax3 of the bearing pin 63 is located on the inner side (rotation axis Ax1) of the central axis Ax2 of the outer pin 23.

Furthermore, in this embodiment, the diameter of the support 8 (its outer peripheral surface 81) is one size smaller than the diameter of an imaginary circle (tooth tip circle) passing through the tips of the internal teeth 21 in the internal gear 2. Therefore, the outer peripheral surface 81 of the support 8 is not in contact with the multiple outer pins 23, and a gap is generated between the outer peripheral surface 81 of the support 8 and the multiple outer pins 23.

As a modification of the second embodiment, as shown in FIG. 15, each of the multiple bearing pins 63 may be integrated with each of the multiple outer pins 23. That is, in the example of FIG. 15, one pin is extended in the axial direction, and a part of it functions as the bearing pin 63, and another part functions as the outer pin 23. Here, since the diameter φ2 of the bearing pin 63 is different from the diameter φ1 of the outer pin 23, the central axis Ax2 around which the outer pin 23 rotates (spins) and the central axis Ax2 around which the bearing pin 63 rotates (spins) are arranged on a straight line. This allows the pin in which the outer pin 23 and the bearing pin 63 are integrated to rotate around the central axis Ax2. In the configuration of this modification, the outer pin 23 and the bearing pin 63 rotate together and cannot rotate individually, but it is possible to reduce the number of parts.

As another variation of the second embodiment, the second bearing member 7 can be omitted as appropriate. In other words, the gear device 1A only needs to include the internal gear 2, the planetary gear 3, the multiple inner pins 4, and the first bearing member 6A, and the second bearing member 7 may be omitted.

As another variation of the second embodiment, the diameter φ2 of the bearing pin 63 may be smaller than the diameter φ1 of the outer pin 23. Furthermore, the number of bearing pins 63 and the number of outer pins 23 may differ.

As another modification of the second embodiment, the diameter of the outer peripheral surface 81 of the support 8 may be the same as the diameter of a virtual circle (tooth tip circle) passing through the tips of the internal teeth 21 of the internal gear 2. In this case, as in the first embodiment, the position of the support 8 is restricted by contacting the outer peripheral surface 81 with a plurality of outer pins 23.

The configuration of embodiment 2 (including modifications) can be applied in appropriate combination with the configuration described in embodiment 1 (including modifications).

(Embodiment 3)
As shown in Figures 16 and 17, the internal meshing planetary gear device 1B according to this embodiment (hereinafter also simply referred to as "gear device 1B") differs from the gear device 1A according to embodiment 2 in the configuration of the first bearing member 6B. Hereinafter, configurations similar to those in embodiment 2 will be given the same reference numerals and descriptions thereof will be omitted as appropriate. Figure 16 is a schematic cross-sectional view of the gear device 1B. Figure 17 is a cross-sectional view taken along line B1-B1 in Figure 16 and a partially enlarged view thereof. However, in Figure 17, hatching has been omitted for parts other than the eccentric shaft 54 and the cage 64, even in the cross section.

In this embodiment, the first bearing member 6B is configured such that the multiple bearing pins 63 can move relative to the first outer ring 62 in the circumferential direction of the first outer ring 62. On the other hand, in the internal gear 2, as in embodiment 2, the multiple outer pins 23 are restricted from moving relative to the gear body 22 in the circumferential direction of the gear body 22. Therefore, the multiple bearing pins 63 can move relative to the multiple outer pins 23 in the circumferential direction of the first outer ring 62. As a result, in the gear device 1B according to this embodiment, the multiple bearing pins 63 rotate relative to the multiple outer pins 23 as the multiple inner pins 4 rotate relative to the gear body 22.

Specifically, the first bearing member 6B has a retainer 64 as shown in FIG. 17. The multiple bearing pins 63 are arranged between the inner peripheral surface 621 of the first outer ring 62 and the outer peripheral surface 611 of the first inner ring 61 in a rotatable state, and are held by the retainer 64. The retainer 64 holds the multiple bearing pins 63 at equal pitches in the circumferential direction of the first outer ring 62. Furthermore, the retainer 64 is not fixed to the inner peripheral surface 621 of the first outer ring 62 and the outer peripheral surface 611 of the first inner ring 61, and is rotatable relative to each of the first inner ring 61 and the first outer ring 62 around the rotation axis Ax1. As a result, the multiple bearing pins 63 held by the retainer 64 move in the circumferential direction of the first outer ring 62 as the retainer 64 rotates. In other words, the retaining structure for the multiple bearing pins 63 includes a retainer 64 disposed between the first outer ring 62 and the first inner ring 61. The retainer 64 is made of metal, for example.

In short, in this embodiment, the retaining structure of the outer pin 23 is the gear groove 222, while the retaining structure of the bearing pin 63 is the retainer 64, and the retaining structures of the outer pin 23 and the bearing pin 63 differ in type. In this case, it is only necessary to form the gear groove 222 as the retaining structure for the body 11, which makes it easier to machine the body 11.

As a modification of the third embodiment, the diameter φ2 of the bearing pin 63 may be the same as the diameter φ1 of the outer pin 23 (φ1 = φ2), or the diameter φ2 of the bearing pin 63 may be smaller than the diameter φ1 of the outer pin 23.

As another variation of the third embodiment, the retainer 64 is not essential as long as the bearing pins 63 are capable of rotating relative to the outer pins 23 as the inner pins 4 rotate relative to the gear body 22. The material of the retainer 64 is not limited to metal, and may be, for example, a resin such as engineering plastic.

The configuration of embodiment 3 (including modifications) can be applied in appropriate combination with the configurations (including modifications) described in embodiment 1 or embodiment 2.

(summary)
As described above, the internally meshing planetary gear device (1, 1A, 1B) according to the first aspect includes an internal gear (2), a planetary gear (3), a plurality of inner pins (4), a first bearing member (6, 6A, 6B), and a second bearing member (7). The internal gear (2) has an annular gear body (22) and a plurality of outer pins (23) that are held on an inner peripheral surface (221) of the gear body (22) in a rotatable state and form the internal teeth (21). The planetary gear (3) has external teeth (31) that partially mesh with the internal teeth (21). The multiple inner pins (4) are inserted into a plurality of loose fitting holes (32) formed in the planetary gear (3), respectively, and rotate relative to the gear body (22) while revolving within the loose fitting holes (32). The first bearing member (6, 6A, 6B) and the second bearing member (7) rotatably support the multiple inner pins (4) with respect to the gear body (22) at two locations in the direction of the rotation axis (Ax1). The first bearing member (6, 6A, 6B) has a first inner ring (61), a first outer ring (62), and multiple bearing pins (63). The multiple inner pins (4) are located inside the second bearing member (7) when viewed from one side in the direction of the rotation axis (Ax1).

According to this embodiment, the first bearing member (6, 6A, 6B) and the second bearing member (7) rotatably support the multiple inner pins (4) relative to the gear body (22) at two points in the direction of the rotation axis (Ax1), so that the multiple inner pins (4) are supported at two points relative to the gear body (22). Therefore, compared to a single-point support in which the multiple inner pins (4) are supported relative to the gear body (22) at one point in the direction of the rotation axis (Ax1), it is easier to withstand loads such as bending forces (bending moment loads) relative to the rotation axis (Ax1). Moreover, the first bearing member (6, 6A, 6B) has a first inner ring (61), a first outer ring (62), and multiple bearing pins (63). In other words, the first bearing member (6, 6A, 6B) is a needle bearing with the bearing pins (63) as "rolling bodies (rollers)" and can withstand relatively large loads in the radial direction. Furthermore, even though it is supported at two points, the second bearing member (7) is located outside the multiple inner pins (4) when viewed from one side in the direction of the rotation axis (Ax1), so the limited space inside the multiple inner pins (4) can be made into a relatively simple structure. Therefore, there is an advantage in that it is easy to simplify the structure.

In the internally meshing planetary gear device (1, 1A, 1B) according to the second embodiment, in the first embodiment, the first bearing member (6, 6A, 6B) is located on the same side of the rotation axis (Ax1) as the second bearing member (7) with respect to the multiple outer pins (23).

This configuration allows multiple inner pins (4) to be effectively supported at two points, and also makes it easier to reduce the size in the direction of the rotation axis (Ax1).

The internally meshing planetary gear device (1, 1A, 1B) according to the third aspect further includes a retaining member (55) that retains the multiple inner pins (4) in the first or second aspect. The first bearing member (6, 6A, 6B) and the second bearing member (7) are located outside the retaining member (55) when viewed from one side in the direction of the rotation axis (Ax1).

This aspect makes it easier to reduce the size in the direction of the rotation axis (Ax1).

In the internally meshing planetary gear device (1, 1A, 1B) according to the fourth aspect, in any of the first to third aspects, each of the multiple bearing pins (63) is integral with each of the multiple outer pins (23).

This makes it easier to keep the number of parts to a minimum.

In the internally meshing planetary gear device (1, 1A, 1B) according to the fifth aspect, in any of the first to third aspects, each of the multiple bearing pins (63) is separate from each of the multiple outer pins (23).

According to this embodiment, the rotation of the bearing pin (63) and the rotation of the outer pin (23) are less likely to interfere with each other.

In the internally meshing planetary gear device (1, 1A, 1B) according to the sixth aspect, in any of the first to fifth aspects, the multiple bearing pins (63) are located between the second bearing member (7) and the multiple outer pins (23) in the direction of the rotation axis (Ax1).

According to this embodiment, the first bearing member (6, 6A, 6B) can effectively receive the radial load.

In the seventh aspect of the internally meshing planetary gear device (1, 1A, 1B), in any of the first to sixth aspects, the second bearing member (7) has a second outer ring (72) and a second inner ring (71). One end of the multiple bearing pins (63) in the direction of the rotation axis (Ax1) contacts the second outer ring (72) or the second inner ring (71).

According to this embodiment, the movement of the bearing pin (63) in one direction along the rotation axis (Ax1) can be restricted.

In the internally meshing planetary gear device (1, 1A, 1B) according to the eighth aspect, in any of the first to seventh aspects, the holding structure for the multiple outer pins (23) includes multiple gear grooves (222) formed on the inner circumferential surface (221) of the gear body (22). The holding structure for the multiple bearing pins (63) includes multiple bearing grooves (622) formed on the inner circumferential surface (621) of the first outer ring (62). The multiple bearing grooves (622) have a smaller ratio of depth to diameter of the pins they hold than the multiple gear grooves (222).

This embodiment makes it easier to reduce frictional resistance between the inner surface of the bearing groove (622) and the bearing pin (63).

The internally meshing planetary gear device (1, 1A, 1B) according to the ninth aspect is configured in any one of the first to eighth aspects to extract the rotational force of the gear body (22) as an output when the multiple inner pins (4) rotate relative to the gear body (22).

According to this embodiment, the gear body (22) or a member integrated with the gear body (22) can be used as the rotating member.

In the internally meshing planetary gear device (1, 1A, 1B) according to the tenth aspect, in any of the first to ninth aspects, the second bearing member (7) receives a load at least along the direction of the rotation axis (Ax1).

According to this embodiment, the load in the thrust direction can be received by the second bearing member (7).

In the internally meshing planetary gear device (1, 1A, 1B) according to the eleventh aspect, in any of the first to tenth aspects, the second bearing member (7) includes a deep groove ball bearing.

According to this embodiment, the load in the thrust direction can be received by the second bearing member (7).

The wheel device (W1) according to the twelfth aspect includes an internally meshing planetary gear device (1, 1A, 1B) according to any one of the first to eleventh aspects, and a wheel body (102) that rolls on a running surface due to the rotational output generated when the multiple inner pins (4) rotate relative to the gear body (22).

This has the advantage of making it easier to simplify the structure.

The vehicle (V1) according to the thirteenth aspect includes the wheel device (W1) according to the twelfth aspect and a vehicle body (100) that holds the wheel device (W1).

This has the advantage of making it easier to simplify the structure.

The configurations according to the second to eleventh aspects are not essential to the internally meshing planetary gear device (1, 1A, 1B) and may be omitted as appropriate.

DESCRIPTION OF SYMBOLS 1, 1A, 1B Internally meshing planetary gear device 2 Internal gear 3 Planetary gear 4 Inner pin 6, 6A, 6B First bearing member 7 Second bearing member 21 Internal teeth 22 Gear body 23 Outer pin 31 External teeth 32 Loose fitting hole 55 Retaining member 61 First inner ring 62 First outer ring 63 Bearing pin 71 Second inner ring 72 Second outer ring 100 Vehicle body 102 Wheel body 221 Inner peripheral surface (of gear body) 222 Gear groove 621 Inner peripheral surface (of first outer ring) 622 Bearing groove Ax1 Rotating shaft V1 Vehicle W1 Wheel device

Claims (12)

an internal gear including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
a planetary gear having external teeth that partially mesh with the internal teeth;
a plurality of inner pins that are inserted into a plurality of loose-fitting holes formed in the planetary gear and rotate relatively to the gear body while revolving within the loose-fitting holes;
a first bearing member and a second bearing member that rotatably support the inner pins with respect to the gear body at two locations in a rotation axis direction,
the first bearing member has a first inner ring, a first outer ring and a plurality of bearing pins;
the inner pins are located on the inner side of the second bearing member when viewed from one side in the rotation axis direction,
The first bearing member is located on the same side as the second bearing member in the rotation axis direction with respect to the plurality of outer pins.
Internally meshing planetary gear set. an internal gear including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
a planetary gear having external teeth that partially mesh with the internal teeth;
a plurality of inner pins that are inserted into a plurality of loose-fitting holes formed in the planetary gear and rotate relative to the gear body while revolving within the loose-fitting holes;
a first bearing member and a second bearing member that rotatably support the inner pins with respect to the gear body at two locations in a rotation axis direction,
the first bearing member has a first inner ring, a first outer ring and a plurality of bearing pins;
the inner pins are located on the inner side of the second bearing member when viewed from one side in the rotation axis direction,
The plurality of bearing pins are located between the second bearing member and the plurality of outer pins in the rotation axis direction.
Internally meshing planetary gear set. an internal gear including an annular gear body and a plurality of outer pins that are rotatably held on an inner peripheral surface of the gear body and form internal teeth;
a planetary gear having external teeth that partially mesh with the internal teeth;
a plurality of inner pins that are inserted into a plurality of loose-fitting holes formed in the planetary gear and rotate relative to the gear body while revolving within the loose-fitting holes;
a first bearing member and a second bearing member that rotatably support the inner pins with respect to the gear body at two locations in a rotation axis direction,
the first bearing member has a first inner ring, a first outer ring and a plurality of bearing pins;
the inner pins are located on the inner side of the second bearing member when viewed from one side in the rotation axis direction,
the second bearing member has a second outer ring and a second inner ring,
One ends of the plurality of bearing pins in the rotation axis direction contact the second outer ring or the second inner ring.
Internally meshing planetary gear set. The inner pins are further provided with a holding member for holding the inner pins.
the first bearing member and the second bearing member are located outside the holding member when viewed from one side in the rotation axis direction;
The internal meshing planetary gear device according to any one of claims 1 to 3 . Each of the plurality of bearing pins is integral with each of the plurality of outer pins.
The internal meshing planetary gear device according to any one of claims 1 to 4 . Each of the plurality of bearing pins is separate from each of the plurality of outer pins.
The internal meshing planetary gear device according to any one of claims 1 to 4 . the retaining structure for the outer pins includes a plurality of gear grooves formed on an inner peripheral surface of the gear body,
the retaining structure for the plurality of bearing pins includes a plurality of bearing grooves formed in an inner circumferential surface of the first outer ring,
the plurality of bearing grooves have a ratio of depth to diameter of the pins they hold that is smaller than the ratio of depth to diameter of the pins they hold,
The internal meshing planetary gear device according to any one of claims 1 to 6 . When the plurality of inner pins rotate relative to the gear body, a rotational force of the gear body is output.
The internal meshing planetary gear device according to any one of claims 1 to 7 . The second bearing member receives a load at least along the rotation axis direction.
The internal meshing planetary gear device according to any one of claims 1 to 8 . The second bearing member includes a deep groove ball bearing.
The internal meshing planetary gear device according to any one of claims 1 to 9 . An internal meshing planetary gear device according to any one of claims 1 to 10 ;
and a wheel body that rolls on a running surface by a rotation output generated when the plurality of inner pins rotate relatively to the gear body.
Wheel device. A wheel arrangement according to claim 11 ;
A vehicle body that holds the wheel device.
vehicle.