JP7649673B2 - Gearing - Google Patents

Description

This disclosure relates to a gear device.

Patent Document 1 discloses a gear device incorporating a planetary gear mechanism as a gear mechanism. This type of gear device typically includes a sun gear that rotates integrally with the high-speed shaft, multiple planetary gears that mesh with the sun gear, and an internal gear that meshes with the planetary gears.

JP 2011-220496 A

When using a planetary gear mechanism as the gear mechanism, it is necessary to place the sun gear and planetary gears inside the internal gear. This causes the problem that the number of gears increases in the cross section perpendicular to the axial direction of the high-speed shaft, resulting in heavy weight.

One of the objectives of this disclosure is to provide a gear device that can be made lighter.

The gear device disclosed herein is a gear device that includes a crankshaft having an eccentric body, an external gear that oscillates due to the eccentric body, and an internal gear that meshes with the external gear, and the external gear has multiple external teeth, and the external gear as a whole forms an N-sided polygon when N is a natural number of 3 or more, and the outer circumferential shape of the external teeth forms an arc shape that is convex radially outward with respect to a line connecting adjacent vertices of the N-sided polygon.

The gear device disclosed herein can be made lighter.

FIG. 2 is a side cross-sectional view of the gear device according to the embodiment. 2 is a cross-sectional view taken along line AA of FIG. 1. FIG. 4 is a first explanatory diagram showing a motion locus of a first external gear. FIG. 4 is a second explanatory diagram showing the movement locus of the first external gear. FIG. 4 is a diagram showing a part of the movement trajectory of FIG. 3 . This is a cross-sectional view taken along line B-B of FIG. FIG. 4 is a first explanatory diagram showing an operating state of the first external gear and the second external gear. FIG. 4 is a second explanatory diagram showing an operating state of the first external gear and the second external gear. FIG. 2 is a diagram showing a first external gear set according to the embodiment. This is a cross-sectional view taken along the line CC of FIG. 2 is a diagram showing a part of a cross section taken along the line DD in FIG. 1;

The following describes the embodiments. Identical components are given the same reference numerals, and duplicate explanations will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of convenience. The drawings should be viewed according to the orientation of the reference numerals.

Refer to Figure 1. The gear device 10 comprises a crankshaft 14 having at least one eccentric body 12A, 12B, external gears 16A-16D that oscillate due to the eccentric bodies 12A, 12B, and internal gears 18A-18D that mesh with the external gears 16A-16D. The gear device 10 comprises a low-speed shaft 20 that is connected to the crankshaft 14 via a power transmission path that passes through the external gears 16A-16D and the internal gears 18A-18D, and a casing 22 that houses the external gears 16A-16D.

One of the crankshaft 14 and the low-speed shaft 20 is an input shaft that receives rotational power from a drive source (not shown), and the other is an output shaft that outputs rotational power to a driven device. In this embodiment, the crankshaft 14 is the input shaft, and the low-speed shaft 20 is the output shaft. The drive source is, for example, a motor, a gear motor, an engine, etc. When the input shaft rotates, the crankshaft 14 becomes a high-speed shaft that rotates at a relatively high speed, and the low-speed shaft 20 rotates at a relatively low speed. For ease of explanation, one side of the crankshaft 14 in the axial direction X (the right side in FIG. 1) will be referred to as the input side, and the opposite side will be referred to as the anti-input side.

The eccentric bodies 12A and 12B are provided at a midpoint in the axial direction X of the crankshaft 14. The axis C1 of the eccentric bodies 12A and 12B is eccentric from the rotation center line CL1 of the crankshaft 14 by an eccentricity amount e1. The eccentric bodies 12A and 12B have a circular shape centered on the axis C1.

In this embodiment, at least one eccentric body 12A, 12B is provided, which is a first eccentric body 12A arranged on the input side and a second eccentric body 12B arranged on the opposite input side. The multiple eccentric bodies 12A, 12B have different eccentric phases from each other. The eccentric phase here refers to the phase around the rotation center line CL1 in the eccentric direction from the rotation center line CL1 of the crankshaft 14 toward the axis C1 of the eccentric bodies 12A, 12B. When the number of eccentric bodies 12A, 12B is M (M is a natural number of 2 or more), the eccentric phases of the multiple eccentric bodies 12A, 12B are shifted by 360°/M. Since M is 2 in this embodiment, the eccentric phases of the first eccentric body 12A and the second eccentric body 12B are shifted by 180° (=360°/2).

The crankshaft 14 is composed of multiple shaft members 24A, 24B, 24C having a shape obtained by dividing the crankshaft 14 in the axial direction X. The multiple shaft members 24A, 24B, 24C include split shaft members 24A, 24B on which individual eccentric bodies 12A, 12B are provided, and a connecting shaft member 24C that connects adjacent split shaft members 24A, 24B. The split shaft members 24A, 24B include a first split shaft member 24A on which a first eccentric body 12A is provided, and a second split shaft member 24B on which a second eccentric body 12B is provided. The split shaft members 24A, 24B and the connecting shaft member 24C are connected so as to be able to rotate together by spline fitting or the like.

The crankshaft 14 is rotatably supported by crank bearings 26A and 26B. The crank bearings 26A and 26B include a first crank bearing 26A disposed between the casing 22 and the crankshaft 14, and a second crank bearing 26B disposed between the low speed shaft 20 and the crankshaft 14.

The low-speed shaft 20 is rotatably supported by a low-speed bearing 28. The low-speed bearing 28 is disposed between the casing 22 and the low-speed shaft 20.

The gear device 10 includes a plurality of external gear units 30A, 30B having at least one external gear 16A-16D. Each of the plurality of external gear units 30A, 30B oscillates due to an individual eccentric body 12A, 12B. The plurality of external gear units 30A, 30B includes a first external gear unit 30A oscillated due to a first eccentric body 12A, and a second external gear unit 30B oscillated due to a second eccentric body 12B. The first external gear unit 30A includes a first external gear 16A arranged on the input side and a second external gear 16B arranged on the opposite input side. The second external gear unit 30B includes a third external gear 16C arranged on the input side and a fourth external gear 16D arranged on the opposite input side.

In addition to the external gears 16A to 16D, the external gear units 30A and 30B are provided with flange bodies 32A to 32C that are integrated with the external gears 16B to 16D. The flange bodies 32A to 32C are part of the first external gear unit 30A and include a first flange body 32A that is integrated with the second external gear 16B. In addition, the flange bodies 32A to 32C include a second flange body 32B that is integrated with the third external gear 16C and a third flange body 32C that is integrated with the fourth external gear 16D. The second flange body 32B and the third flange body 32C are part of the second external gear unit 30B. The flange bodies 32A to 32C in this embodiment are provided as part of the same member as the external gears 16B to 16D that are integrated with the flange bodies 32A to 32C, but may be provided separately from the external gears 16B to 16D. The flange bodies 32A to 32C are disposed axially outward from the meshing portions 40a of the external teeth 40 of the external gears 16B to 16D that are integrated with the flange bodies 32A to 32C, and are provided so as to protrude radially outward from the meshing portions 40a (see FIG. 11). The meshing portions 40a of the external teeth 40 here refer to the locations that mesh with the internal teeth 48 of the internal gears 18B to 18D.

The external gears 16A-16D are rotatably supported on the eccentric bodies 12A, 12B by eccentric bearings 34. The eccentric bearings 34 are arranged between the eccentric bodies 12A, 12B of the crankshaft 14 and through holes 36 formed in the external gears 16A-16D of the external gear units 30A, 30B corresponding to the eccentric bodies 12A, 12B. The eccentric bearings 34 are rolling bearings such as roller bearings or ball bearings. In this embodiment, a common eccentric bearing 34 is arranged between the multiple external gears 16A-16D belonging to one external gear unit 30A, 30B and the eccentric bodies 12A, 12B.

The gear device 10 includes a plurality of internal gear units 38A, 38B each consisting of at least one internal gear 18A-18D. The plurality of internal gear units 38A, 38B correspond to the plurality of external gear units 30A, 30B individually, and mesh with the external gears 16A-16D of the corresponding external gear units 30A, 30B. The plurality of internal gear units 38A, 38B include a first internal gear unit 38A corresponding to the first external gear unit 30A, and a second internal gear unit 38B corresponding to the second external gear unit 30B. The first internal gear unit 38A includes a first internal gear 18A meshing with the first external gear 16A, and a second internal gear 18B meshing with the second external gear 16B. The second internal gear unit 38B includes a third internal gear 18C that meshes with the third external gear 16C, and a fourth internal gear 18D that meshes with the fourth external gear 16D. The internal gears 18A to 18D are integrated with the casing 22.

One of the external gears 16A-16D and the internal gears 18A-18D is a rotating gear that rotates on its own axis, and the other is a constrained gear whose rotation is constrained. In this embodiment, the external gears 16A-16D are rotating gears, and the internal gears 18A-18D are constrained gears. In this case, the casing 22 is fixed to an external member separate from the driven device driven by the gear device 10, causing the internal gears 18A-18D to function as constrained gears whose rotation is constrained. In addition, the external gears 16A-16D, which are rotating gears, are connected by carriers 74A, 74B and pin members 76A, 76B, which will be described later, so as to synchronize the rotation component of the rotating gear with the low-speed shaft 20.

See Figure 2. In the following cross-sectional views, the eccentric bearing 34 is shown diagrammatically, and the external shapes of the internal gears 18A-18D are mainly shown. In addition, the first external gear 16A and the first internal gear 18A are shown here, and the contents common to the other external gears 16B-16D and internal gears 18B-18D are explained.

The external gears 16A to 16D each have a plurality of external teeth 40. When N is a finite natural number equal to or greater than 3, the plurality of external teeth 40 as a whole form an N-sided polygon on the outer periphery. In this specification, "shape" does not only mean a shape that geometrically closely matches the shape being referred to, but also includes a shape similar to the shape being referred to. In this embodiment, N is 3, and the plurality of external teeth 40 as a whole form an N-sided Reuleaux polygon (more specifically, a Reuleaux triangle), that is, an odd-sided shape on the outer periphery. This condition is met in a cross section perpendicular to the axial direction X of the crankshaft 14.

The N-sided polygon formed by the multiple external teeth 40 has N vertices 42. The N vertices 42 are equidistant from the center C2 of the N-sided polygon, and are located at positions shifted in central angle by 360°/N (120° in this embodiment). The external teeth 40 are formed by each side of the N-sided polygon formed by the multiple external teeth 40, and the number of external teeth is N (three in this embodiment). The center C2 of the N-sided polygon is the axis C2 of the external gears 16A to 16D.

The outer peripheral shape of each of the multiple external teeth 40 is an arc shape that is convex radially outward with respect to the line L1 that connects the adjacent vertices 42 of the N-gon. To satisfy this condition, the outer peripheral shape of the external teeth 40 may be a single curve, a combination of multiple curves with different curvatures, or a combination of curves and straight lines.

The internal gears 18A to 18D have a number of internal teeth 48 that are linear along each side 46 of the (N+1) polygon 44 in the inner peripheral shape. The number of internal teeth of the internal gears 18A to 18D is the same as the number of sides of the (N+1) polygon 44, which is N+1 (four in this embodiment). In addition to the (N+1) sides 46, the (N+1) polygon 44 here has (N+1) vertices 50. The (N+1) vertices 50 are located at equal distances from the center C3 of the (N+1) polygon 44 and are shifted in central angle by 360°/(N+1) (90° in this embodiment). Since N is 3 in this embodiment, the (N+1) polygon 44 is a quadrangle, that is, an even-numbered polygon. The sides 46 of the (N+1) polygon 44 need only be linear overall, and may be a shape represented by a single straight line or a shape that combines straight lines and curves. This condition is met in a cross section perpendicular to the axial direction X of the crankshaft 14. The center C3 of the (N+1) polygon is the axis C3 of the internal gears 18A-18D.

The inner peripheral shape of the internal teeth 48 at least partially overlaps the side 46 of the (N+1) polygon 44. In this embodiment, the overlapping range of the inner peripheral shape of the internal teeth 48 with the side 46 is a range excluding the vertex of the (N+1) polygon 44. This overlapping range is, for example, a range of 3/4 or more of the length of the side 46 of the (N+1) polygon 44. In addition, the inner peripheral shape of the internal teeth 48 may overlap the entire length of the side 46 of the (N+1) polygon 44. The inner peripheral shape of the internal teeth 48 will be generally linear, like the side 46 of the (N+1) polygon 44.

The operation of the gear device 10 described above will now be explained. Here, the operation will be described when the rotating gears are the external gears 16A-16D, the restraining gears are the internal gears 18A-18D, the crankshaft 14 is the input shaft, and the low speed shaft 20 is the output shaft. Please refer to Figures 3 and 4. Figures 3 and 4 show the motion trajectory of the first external gear 16A when the crankshaft 14 rotates half a revolution, with Figure 3 showing the motion trajectory of the first half, and Figure 4 showing the motion trajectory of the latter half.

When rotational power is transmitted from the drive unit to the input shaft (crankshaft 14), the external gears 16A-16D oscillate with relative rotation to the eccentric bodies 12A, 12B in response to the rotation of the input shaft in the rotation direction Da, due to the eccentric bodies 12A, 12B. Oscillation here refers to the movement of the axis C2 of the external gears 16A-16D rotating in the rotation direction Da around the rotation center line CL1 while being eccentric with respect to the rotation center line CL1 of the crankshaft 14.

In the process of the external gears 16A-16D oscillating with the relative rotation with respect to the eccentric bodies 12A, 12B, the external gears 16A-16D move so as to change the meshing position with respect to the internal gears 18A-18D in the circumferential direction (direction Db) of the crankshaft 14. In this process, the external gears 16A-16D can be said to move as if they are rolling relative to the internal gears 18A-18D. At this time, as shown in FIG. 5, the external gears 16A-16D and the internal gears 18A-18D mesh with each other, and a rotational force Fa acts on the rotating gears (external gears 16A-16D). When the external gears 16A-16D become rotating gears, this rotational force Fa acts in the opposite direction to the rotation direction Da of the input shaft. As a result, when the external gears 16A to 16D oscillate, the rotating gears (external gears 16A to 16D) rotate in response to the movement due to the rotational force Fa acting on the rotating gear. When the rotating gear rotates, the rotation component of the rotating gear is transmitted to the output shaft (low speed shaft 20), causing the output shaft (low speed shaft 20) to rotate.

As described above, when the input shaft rotates, the external gears 16A-16D oscillate, changing the meshing positions of the external gears 16A-16D and the internal gears 18A-18D, causing the output shaft to rotate. Here, the gear ratio, which is the ratio of the rotational speed of the output shaft to that of the input shaft, is the number of teeth of the rotating gear. In this embodiment, the external gears 16A-16D, which serve as the rotating gears, have three teeth, and the low-speed shaft 20 serves as the output shaft, so the reduction ratio as the gear ratio is three. If the internal gears 18A-18D were to serve as the rotating gears, the reduction ratio as the gear ratio would be four.

The effects of the above gear device 10 will now be explained.

When using N-angled external gears 16A-16D as the gear mechanism, it is sufficient to place the external gears 16A-16D inside the internal gears 18A-18D. Therefore, compared to when a planetary gear mechanism is used, the number of gears can be reduced in a cross section perpendicular to the axial direction of the crankshaft 14, and the weight of the gear device 10 can be reduced accordingly.

The outer periphery of the external teeth 40 of the external gears 16A to 16D is an arc shape that is convex radially outward with respect to the line L1 that connects the adjacent vertices 42 of the N-sided polygon. Therefore, the outer periphery of the external teeth 40 is a shape that has no significant recesses overall, that is, a shape without a tooth base, which is the equivalent of an involute tooth profile, and it is not necessary to consider the tooth base strength.

The internal teeth 48 of the internal gears 18A-18D are linear along the sides 46 of the (N+1) polygon 44. When involute tooth profiles mesh with each other, the curved external and internal teeth with a relatively large curvature mesh with each other, and the curvature at the meshing points is large. In contrast, according to this embodiment, the arc-shaped (curved) external teeth 40 mesh with the linear internal teeth 48 that are close to a straight line, and the curvature at the meshing points is significantly smaller. As a result, the contact stress (Hertz stress) between the external teeth 40 and the internal teeth 48 can be reduced, which is advantageous for transmitting large torque.

Next, other features of the gear device 10 will be described.

Refer to Figures 2 and 6. The first external gear 16A and the second external gear 16B of the first external gear unit 30A oscillate with a common eccentric phase. The axis C2 of the first external gear 16A and the second external gear 16B move to rotate in the same direction around the rotation center line CL1 of the crankshaft 14 with the same eccentric amount and eccentric direction. To satisfy this condition, the first external gear 16A and the second external gear 16B of this embodiment oscillate by a common first eccentric body 12A. In addition, to satisfy this condition, the first external gear 16A and the second external gear 16B may be oscillated by multiple eccentric bodies that are separate from each other and have a common eccentric phase. The first external gear 16A and the second external gear 16B are connected by a restricting member 56 (described later) as a connecting member so as to restrict the relative rotation.

The phases of the first external gear 16A and the second external gear 16B of the first external gear unit 30A are shifted from each other by 360/(N x 2) [°]. Here, the phases of the external gears 16A to 16D refer to the phases around the axis C2 of the external gears 16A to 16D. In this embodiment, since N = 3, the phases of the first external gear 16A and the second external gear 16B are shifted by 60°.

The phases of the first internal gear 18A and the second internal gear 18B of the first internal gear unit 38A are shifted from each other by 360/{(N+1)×2} [°]. Here, the phases of the internal gears 18A to 18D refer to the phases of the internal gears 18A to 18D around the axis C3. In this embodiment, since N=3, the phases of the first internal gear 18A and the second internal gear 18B are shifted by 45°.

The above advantages will be explained with reference to Figures 7 and 8. Figure 8 shows a state in which the eccentric phase of the first eccentric body is shifted by 45° from the state in Figure 7. The external teeth 40 of the external gears 16A and 16B can mesh with the internal gears 18A and 18B at points close to the vertices 42 of the N-sided polygon. On the other hand, the external teeth 40 of the external gears 16A and 16B cannot mesh with the internal gears 18A and 18B at points close to the midpoint 52 in the middle of the adjacent vertices 42.

Here, by satisfying the above-mentioned conditions, as shown in FIG. 7, even when the first external gear 16A cannot mesh with the first internal gear 18A at a point P1 close to the midpoint 52 of the first external gear 16A, the second internal gear 18B can be meshed with the second external gear 16B at a point P2 close to the apex 42. Similarly, as shown in FIG. 8, even when the second internal gear 18B cannot mesh with the first external gear 16B at a point P3 close to the midpoint 52 of the second external gear 16B, the first external gear 16A can be meshed with the first internal gear 18A at a point P4 close to the apex 42 of the first external gear 16A. In other words, the first external gear 16A and the second external gear 16B can be alternately meshed with the internal gears 18A and 18B of the first internal gear unit 38A. As a result, regardless of the rotation phase of the input shaft, the first external gear unit 30A as a whole can maintain a state of meshing with the internal gears 18A and 18B of the first internal gear unit 38A. As a result, torque can be transmitted stably and continuously between the external gear units 30A, 30B and the internal gear units 38A, 38B.

The above-mentioned phase relationship described here with respect to the first external gear unit 30A is similarly satisfied by the third external gear 16C and the fourth external gear 16D of the second external gear unit 30B. Moreover, the above-mentioned phase relationship described here with respect to the first internal gear unit 38A is similarly satisfied by the third internal gear 18C and the fourth internal gear 18D of the second internal gear unit 38B. Therefore, the effect of stably and continuously transmitting the torque described above can also be obtained between the second external gear unit 30B and the second internal gear unit 38B.

Refer to Figures 1 and 9. The two external gear units 30A, 30B are provided with two gear sets 54A, 54B consisting of two external gears 16A to 16D belonging to different external gear units 30A, 30B. The two gear sets 54A, 54B include a first gear set 54A and a second gear set 54B. The first gear set 54A consists of a first external gear 16A belonging to the first external gear unit 30A and a fourth external gear 16D belonging to the second external gear unit 30B. The second gear set 54B consists of a second external gear 16B belonging to the first external gear unit 30A and a third external gear 16C belonging to the second external gear unit 30B.

The two external gears 16A, 16D of the first gear set 54A have a phase difference of the same magnitude as the eccentric phase difference between the two eccentric bodies 12A, 12B, that is, a phase difference of 180° (=360/2) between them. The two internal gears 18A, 18D that mesh with the two external gears 16A, 16D of the first gear set 54A also have a phase difference of 180°. The phase here refers to the phase around the axis C3 of the internal gears 18A, 18D. In FIG. 9, the two internal gears 18A, 18D are in rotational symmetry (four-fold symmetry), so the phase difference of 180° does not appear. The phase relationship described here for the first gear set 54A is also satisfied for the second gear set 54B, although not shown.

This allows the individual external gears 16A-16D of the gear sets 54A, 54B to mesh with the individual internal gears 18A-18D simultaneously. This reduces the burden on the individual gears 16A-16D, 18A-18D, thereby increasing the transmission capacity. In addition, the radial moment of the crankshaft 14 caused by the load acting on the axis C1 of the individual eccentric bodies 12A, 12B and the eccentricity of the eccentric bodies 12A, 12B can be offset, improving the rotational balance of the crankshaft 14.

Refer to Figures 1, 2, and 6. The gear device 10 includes a regulating member 56 disposed between the multiple external gears 16A, 16B of the first external gear unit 30A and the first eccentric body 12A. The regulating member 56 in this embodiment is a ring member. The regulating member 56 in this embodiment is provided separately from the eccentric bearing 34. The outer ring 34a of the eccentric bearing 34 is attached to the inside of the regulating member 56 by an interference fit.

The regulating member 56 has an outer peripheral fitting portion 58 provided on the outer peripheral portion of the regulating member 56. The multiple external gears 16A, 16B have inner peripheral fitting portions 60 into which the outer peripheral fitting portions 58 of the regulating member 56 are fitted. The inner peripheral fitting portions 60 are provided on the inner peripheral portion of the through holes 36 of the external gears 16A, 16B. The outer peripheral fitting portions 58 and the inner peripheral fitting portions 60 are shaped to be fitted together so that they can transmit rotational force by contacting each other in the circumferential direction. In this embodiment, a combination of male splines and female splines is used as a shape that satisfies this condition. In addition, for example, a combination of a key and a key groove may be used. The multiple external gears 16A, 16B are connected by a common regulating member 56 so as to regulate relative rotation.

In this way, the multiple external gears 16A, 16B can be connected by using the restricting member 56 arranged in the space between the first eccentric body 12A and the external gears 16A, 16B. Therefore, it is not necessary to secure space in other locations of the external gears 16A, 16B to provide a connecting member (e.g., a pin) that connects the multiple external gears 16A, 16B. As a result, the outer diameter dimensions of the external gears 16A, 16B can be reduced.

The configuration described here with respect to the regulating member 56 is similarly satisfied by the second external gear unit 30B and the second eccentric body 12B. A similar regulating member 56 is also disposed between the multiple external gears 16C, 16D of the second external gear unit 30B and the second eccentric body 12B.

Refer to FIG. 2. Here, the configuration common to the multiple internal gears 18A to 18D will be described with reference to the first internal gear 18A. The internal gears 18A to 18D each include an internal gear member 62 on which the internal teeth 48 are provided, and a gear body 64 integrated with the internal gear member 62. The internal gear member 62 in this embodiment includes multiple internal gear members 62 on which the multiple internal teeth 48 are each provided individually. The multiple internal teeth 48 are composed of multiple internal gear members 62 separated in the circumferential direction. The internal gear member 62 is generally in the shape of a plate extending in a direction along the side 46 of the (N+1) polygon 44.

The gear body 64 is integrated with the casing 22. In this embodiment, the gear body 64 is separate from the casing 22 and is disposed inside the casing 22. The gear body 64 is removably fixed to the casing 22. To achieve this, in this embodiment, the casing 22 is formed by a pair of casing members 68 that are paired above and below, and the multiple casing members 68 are removably connected by bolts. The gear body 64 can be detached from the casing 22 by disassembling the multiple casing members 68.

The gear body 64 has a receiving hole 72 that receives the fixing device 70. The receiving hole 72 opens on the radially opposite side of the gear body 64 from the internal teeth member 62. The fixing device 70 is, for example, a bolt, which is screwed into the internal teeth member 62 to removably fix the internal teeth member 62 to the gear body 64. As a result, the internal teeth member 62 is removably fixed to the gear body 64. With the above configuration, it is possible to replace only the internal teeth member 62 that needs to be replaced, while leaving the other internal teeth members 62 in place.

The external teeth 40 of the above external gears 16A to 16D are harder than the internal teeth 48. This means that the surface hardness of the external teeth 40 is harder than the surface hardness of the internal teeth 48. Surface hardness here refers to, for example, Vickers hardness measured by a method conforming to JIS Z2244. This condition needs to be met between at least one external tooth 40 and at least one internal tooth 48. In this embodiment, all of the external teeth 40 of one external gear 16A are harder than all of the internal teeth 48 of one internal gear 18A.

As a result, even if fatigue occurs due to the meshing of the external gears 16A-16D and the internal gears 18A-18D, the location of the fatigue can be limited to the internal teeth 48, which are less hard than the external teeth 40. Even if fatigue occurs due to the meshing, the replacement work can be completed simply by replacing the internal teeth member 62, which is provided with the internal teeth 48, which has a simpler configuration than the external gears 16A-16D.

Refer to Figure 1. The gear device 10 includes carriers 74A, 74B arranged axially to the sides of the external gear units 30A, 30B, and pin members 76A, 76B inserted into the external gear units 30A, 30B.

The carriers 74A, 74B include an intermediate carrier 74A arranged between adjacent external gear units 30A, 30B, and an end carrier 74B arranged axially outward relative to the multiple external gear units 30A, 30B. The end carrier 74B is integrated with the low-speed shaft 20. In this embodiment, the end carrier 74B is provided integrally as part of the same member as the low-speed shaft 20, but may be provided separately from the low-speed shaft 20. The end carrier 74B is provided so as to protrude radially outward from the low-speed shaft 20. A bearing 78 is provided between the end carrier 74B and the casing 22.

The pin members 76A, 76B connect the external gear units 30A, 30B to the side members 80A, 80B so as to be synchronized with the rotational components of the external gear units 30A, 30B. The side members 80A, 80B refer to members arranged axially to the external gear units 30A, 30B, and in this embodiment, are the carriers 74A, 74B. Here, "connected so as to be synchronized with the rotational components" refers to maintaining the rotational components of the two objects being mentioned at the same magnitude within a numerical range including zero. When the external gears 16A-16D become rotational gears, the pin members 76A, 76B maintain the rotational components of the external gear units 30A, 30B and the side members 80A, 80B at the same magnitude within a numerical range exceeding zero. When the external gears 16A-16D are constrained gears that do not rotate, the pin members 76A, 76B maintain the rotational components of the external gear units 30A, 30B and the side members 80A, 80B at zero. In this case, the rotational components of the external gear units 30A, 30B are constrained by the side members 80A, 80B and the pin members 76A, 76B, causing the external gears 16A-16D to function as constrained gears.

The pin members 76A and 76B of this embodiment include an intermediate pin member 76A that connects the first external gear unit 30A to the intermediate carrier 74A as the first side member 80A, and an end pin member 76B that connects the second external gear unit 30B to the end carrier 74B as the second side member 80B. The intermediate pin member 76A of this embodiment connects the second external gear unit 30B in addition to the intermediate carrier 74A so as to be synchronized with the rotation component of the first external gear unit 30A. The end pin member 76B connects the end carrier 74B so as to be synchronized with the rotation component of the second external gear unit 30B. As a result, all the external gear units 30A and 30B are connected by the intermediate pin member 76A and the end pin member 76B so that the rotation components of the carriers 74A and 74B are synchronized.

Refer to Figures 1 and 10. The intermediate pin members 76A are provided at intervals around the axis C3 of the internal gears 18A to 18D. The intermediate pin member 76A includes an intermediate carrier pin portion 82 that is inserted into the intermediate carrier 74A, and gear pin portions 84A, 84B that are inserted into the external gear units 30A, 30B. The gear pin portions 84A, 84B include a first gear pin portion 84A that is inserted into the first external gear unit 30A, and a second gear pin portion 84B that is inserted into the second external gear unit 30B.

The intermediate carrier 74A has an intermediate carrier pin hole 86 through which the intermediate carrier pin portion 82 is inserted so as to be rotatable relative to the intermediate carrier 74A. A bearing 88 is disposed between the intermediate carrier pin hole 86 and the intermediate carrier pin portion 82. The intermediate carrier pin portion 82 is rotatably supported by the intermediate carrier 74A via the bearing 88.

The external gear units 30A, 30B have gear pin holes 90 through which the gear pin portions 84A, 84B of the intermediate pin member 76A are inserted so as to be rotatable relative to one another. In this embodiment, the gear pin holes 90 are formed in the first flange body 32A of the first external gear unit 30A and the second flange body 32B of the second external gear unit 30B. The intermediate pin member 76A is inserted through the first flange body 32A and the second flange body 32B. A bearing 92 is disposed between the gear pin hole 90 and the gear pin portions 84A, 84B. The gear pin holes 90 may be formed in the external gears 16A, 16B of the external gear units 30A, 30B instead of the flange bodies 32A-32C.

The axis C4 of the first gear pin portion 84A is eccentric from the axis C5 of the intermediate carrier pin portion 82 by an eccentricity amount e2. This eccentricity direction and eccentricity amount e2 are the same as the eccentricity direction and eccentricity amount e1 of the first eccentric body 12A that oscillates the first external gear unit 30A. This condition is satisfied for all intermediate pin members 76A.

The axis C6 of the second gear pin portion 84B is eccentric from the axis C5 of the intermediate carrier pin portion 82 by an eccentricity amount e2. This eccentricity direction and eccentricity amount e2 are the same as the eccentricity direction and eccentricity amount e2 of the second eccentric body 12B that oscillates the second external gear unit 30B. This condition is met for all intermediate pin members 76A.

This allows the intermediate pin member 76A to be swung so that the axes C4, C6 of the gear pin portions 84A, 84B rotate around the axis C5 of the intermediate carrier pin portion 82. As a result, while the intermediate pin member 76A is supported by the intermediate carrier 74A, it can also be swung as described above in response to the swinging of the external gear units 30A, 30B.

In this way, the gear device 10 is provided with an intermediate carrier 74A that rotatably supports the intermediate pin member 76A. This allows the intermediate carrier 74A to support the intermediate pin member 76A while allowing the first eccentric body 12A of the first external gear unit 30A to oscillate. Another advantage is that the first external gear unit 30A and the second external gear unit 30B, which have different eccentric phases, can be connected by the intermediate pin member 76A while allowing the eccentric bodies 12A and 12B of each external gear unit 30A and 30B to oscillate.

Refer to FIG. 1. The end pin members 76B are provided at intervals around the axis C3 of the internal gears 18A-18D. The end pin members 76B include an end carrier pin portion 96 that is inserted into the end carrier 74B, and a third gear pin portion 98 that is inserted into the second external gear unit 30B. In this embodiment, the gear pin portion 98 is inserted into the third flange body 32C of the second external gear unit 30B.

The axis C7 of the third gear pin portion 98 is eccentric from the axis C8 of the end carrier pin portion 96 by an eccentricity amount e2. This eccentric direction and eccentricity amount e2 are the same as the eccentric direction and eccentricity amount e1 of the second eccentric body 12B that oscillates the second external gear unit 30B. This condition is satisfied for all end pin members 76B. This allows the end pin member 76B to oscillate so that the axis C7 of the third gear pin portion 98 rotates around the axis C8 of the end carrier pin portion 96. In addition, while the second external gear unit 30B is supported by the end pin member 76B, the end pin member 76B can also oscillate in response to the oscillation of the second external gear unit 30B.

Refer to FIG. 11. When viewed from the axial direction X of the crankshaft 14, the pin member 76A is integrated with the flange body 32A through which the pin member 76A is inserted, and is disposed radially outside the meshing portion 40a of the external gear 16B adjacent to the flange body 32A. This position condition only needs to be satisfied by at least one of the multiple pin members 76A inserted into the flange body 32A. In addition, this position condition only needs to be satisfied by the portion of the pin member 76A that is inserted into the flange body 32A (the gear pin portion 84A in this embodiment). In order to satisfy this position condition, it is sufficient that a part of the pin member 76A is disposed radially outside the external gear 16B, and it is not essential that the entire pin member 76A is disposed radially outside the external gear 16B. In this embodiment, the above position condition is satisfied by seven pin members 76A out of a total of eight pin members 76A. Of these, the three pin members 76A and 76B have their entire portions (gear pin portions 84A) inserted into the flange body 32A positioned radially outside the meshing portion 40a of the external gear 16B.

As a result, when using the pin member 76A that is synchronized with the rotation component of the external gear 16B, the outer diameter dimension of the external gear 16B can be made smaller than when the pin member 76A is inserted through the external gear 16B itself.

The positional conditions described here are similarly satisfied for the intermediate pin member 76A, the second flange body 32B, and the third external gear 16C. The same positional conditions are also satisfied for the end pin member 76B, the third flange body 32C, and the fourth external gear 16D. In these cases too, the outer diameter dimensions of the external gears 16C, 16D can be reduced compared to when the pin members 76A, 76B are inserted through the external gears 16C, 16D themselves.

Other variations of each component are described.

So far, we have described the operation when the rotating gears are the external gears 16A-16D and the constraint gears are the internal gears 18A-18D. Alternatively, the rotating gears may be the internal gears 18A-18D and the constraint gears may be the external gears 16A-16D. In this case, the rotation of the external gears 16A-16D can be constrained by inserting the pin members 76A, 76B into the side members 80A, 80B fixed to the external member. In this case, when the input shaft rotates, the external gears 16A-16D (constraint gears) oscillate in a state where their rotation is constrained. In this case, for example, a casing 22 may be used as a connecting means for connecting the rotation components of the internal gears 18A-18D that are the rotating gears to the low-speed shaft 20 so as to synchronize them.

So far, we have described a case where the gear device 10 is used as a reduction device in which the crankshaft 14 is the input shaft and the low-speed shaft 20 is the output shaft. In addition, the gear device 10 may be used as a speed-up device in which the low-speed shaft 20 is the input shaft and the crankshaft 14 is the output shaft. In this case, the gear device 10 as a speed-up device may be used, for example, as a wind power generator, etc.

In the above example, the crankshaft 14 is disposed on the axis C3 of the internal gears 18A to 18D. Alternatively, the crankshaft 14 may be disposed at a radial distance from the axis C3 of the internal gears 18A to 18D at a position offset from the axis C3.

So far, an example has been described in which the outer peripheral shapes of the external gears 16A to 16D have an odd-numbered polygonal shape, and the inner peripheral shapes of the internal gears 18A to 18D have an even-numbered polygonal shape. This is not limiting, and the outer peripheral shapes of the external gears 16A to 16D may have an even-numbered polygonal shape, and the inner peripheral shapes of the internal gears 18A to 18D may have an odd-numbered polygonal shape. In any case, the outer peripheral shapes of the external gears 16A to 16D may have an N-numbered polygonal shape, and the inner peripheral shapes of the internal gears 18A to 18D may have an (N+1)-numbered polygonal shape. Furthermore, N may be 3 or more, and is not particularly limited, and may be 4 or more.

The number of external gears 16A-16D of the external gear units 30A, 30B is not particularly limited. For example, the number of external gears 16A-16D of the external gear units 30A, 30B may be one, or three or more. Furthermore, the number of external gears 16A-16D used in the gear device 10 is not particularly limited. The number of external gears 16A-16D may be one, or five or more, for example.

The phase relationship between the two external gears 16A-16D belonging to the gear sets 54A and 54B is not particularly limited. For example, the two external gears 16A-16D may be shifted in phase with each other in any way.

The multiple internal teeth 48 of the internal gears 18A to 18D do not have to be linear along the sides 46 of the (N+1) polygon 44. The multiple internal teeth 48 may have, for example, an involute tooth profile, a trochoid tooth profile, etc.

When the multiple internal teeth 48 are configured with multiple internal teeth members 62 separated in the circumferential direction, the number of internal teeth 48 provided on each internal teeth member 62 is not particularly limited. For example, in addition to providing one internal tooth 48 on one internal teeth member 62 as in the embodiment, multiple internal teeth 48 may be provided on one internal teeth member 62.

The means for removably fixing the internal teeth member 62 to the gear body 64 is not particularly limited. The internal teeth member 62 may be removably fixed to the gear body 64, for example, by press fitting. The multiple internal teeth 48 of the internal gears 18A to 18D may be formed by a single internal teeth member 62.

Shims for adjusting the position of the internal teeth 48 may be placed between the internal teeth member 62 and the casing 22. The shims are used to adjust the backlash between the external gears 16A-16D and the internal gears 18A-18D by adjusting the thickness of the shims.

In the above example, the gear body 64 of the internal gears 18A to 18D is separate from the casing 22, but the casing 22 may also serve as the gear body 64. Alternatively, the gear body 64 may be provided individually to correspond to each of the multiple internal teeth 48.

The hardness relationship between the external teeth 40 and the internal teeth 48 is not particularly limited. The external teeth 40 may be the same hardness as the internal teeth 48, or may be softer than the internal teeth 48.

The restricting member 56 may be any member capable of connecting the multiple external gears 16A-16D to restrict the relative rotation of the multiple external gears 16A-16D, and is not limited to a ring member. The restricting member 56 may also be a pin member that passes through the multiple external gears 16A-16D. Although an example has been described in which the restricting member 56 is configured separately from the eccentric bearing 34, it may also be configured by the outer ring 34a of the eccentric bearing 34.

The pin members 76A, 76B may directly connect the external gears 16A-16D to the side members 80A, 80B to synchronize the rotational components of the external gear units 30A, 30B with the side members 80A, 80B. The side members 80A, 80B connected to the external gear units 30A, 30B by the pin members 76A, 76B are not limited to the carriers 74A, 74B. The side members 80A, 80B may be, for example, the casing 22, etc.

The gear device 10 does not need to include the intermediate carrier 74A.

The above embodiments and variations are merely examples. The technical ideas that abstract these should not be interpreted as being limited to the contents of the embodiments and variations. Many design changes are possible in the contents of the embodiments and variations, such as changing, adding, or deleting components. In the above embodiments, the contents in which such design changes are possible are emphasized by adding the notation "embodiment". However, design changes are also permitted even in contents without such notation. The hatching on the cross sections in the drawings does not limit the material of the hatched object. The structures referred to in the embodiments and variations naturally include structures that are shifted by the amount of error that can be considered to be the same when manufacturing errors, etc. are taken into account.

10...gear device, 12A, 12B...eccentric body, 14...crankshaft, 16A-16D...external gear, 16A...first external gear, 16B...second external gear, 18A-18D...internal gear, 30A, 30B...external gear unit, 32A-32C...flange body, 40...external teeth, 42...apex, 44...(N+1)-gon, 46...side, 48...internal teeth, 50...apex, 56...regulating member, 62...internal teeth member, 64...gear body, 74A...intermediate carrier, 76A, 76B...pin member.

Claims (7)

A crankshaft having an eccentric body;
an external gear that oscillates due to the eccentric body;
An internal gear meshing with the external gear,
The external gear has a plurality of external teeth,
The plurality of external teeth as a whole have an N-sided polygonal outer periphery, where N is a natural number of 3 or more.
The outer circumferential shape of the external teeth is an arc shape that is convex radially outward with respect to a line connecting adjacent vertices of the N-gon,
The internal gear is a gear device having a plurality of internal teeth that are linearly arranged along each side of an (N+1) polygon on its inner circumference. The plurality of internal teeth are constituted by a plurality of internal teeth members separated in a circumferential direction,
The gear device according to claim 1 , wherein the internal gear comprises a gear body to which the plurality of internally toothed members are removably fixed. 3. A gear arrangement according to claim 1 or 2 , wherein the external teeth are harder than the internal teeth. A crankshaft having an eccentric body;
an external gear that oscillates due to the eccentric body;
An internal gear meshing with the external gear,
The external gear has a plurality of external teeth,
The plurality of external teeth as a whole have an N-sided polygonal outer periphery, where N is a natural number of 3 or more.
The outer circumferential shape of the external teeth is an arc shape that is convex radially outward with respect to a line connecting adjacent vertices of the N-gon,
the external gear includes a first external gear and a second external gear that oscillate with a common eccentric phase,
A gear device in which the phases of the first external gear and the second external gear are shifted from each other by 360/(N×2) [°]. a restricting member disposed between the first external gear and the eccentric body, and between the second external gear and the eccentric body,
The gear device according to claim 4 , wherein the first external gear and the second external gear are connected to each other so that relative rotation between them is restricted by the restricting member. A crankshaft having an eccentric body;
an external gear that oscillates due to the eccentric body;
An internal gear meshing with the external gear,
The external gear has a plurality of external teeth,
The plurality of external teeth as a whole have an N-sided polygonal outer periphery, where N is a natural number of 3 or more.
The outer circumferential shape of the external teeth is an arc shape that is convex radially outward with respect to a line connecting adjacent vertices of the N-gon,
a flange body disposed axially outside the meshing portion of the external teeth;
a pin member that is inserted through the flange body and synchronized with a rotation component of the external gear,
A gear device in which the pin member is disposed radially outward of the meshing portion when viewed from the axial direction. A crankshaft having an eccentric body;
an external gear that oscillates due to the eccentric body;
An internal gear meshing with the external gear,
The external gear has a plurality of external teeth,
The plurality of external teeth as a whole have an N-sided polygonal outer periphery, where N is a natural number of 3 or more.
The outer circumferential shape of the external teeth is an arc shape that is convex radially outward with respect to a line connecting adjacent vertices of the N-gon,
A plurality of external gear units each having at least one of the external gears;
a pin member that is inserted into the external gear unit and synchronized with a rotation component of the external gear unit;
an intermediate carrier disposed between adjacent external gear units and rotatably supporting the pin member.

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