JP7698690B2 - Bearing mechanism and reducer - Google Patents

Description

This invention relates to a bearing mechanism and a reducer.

Patent Document 1 discloses a bearing mechanism in which a roller bearing (eccentric portion bearing) is arranged on the outer peripheral surface of a rotating shaft member (crankshaft), and a limiting member (washer) is arranged next to the roller bearing in the axial direction of the rotating shaft member. The rolling elements of the roller bearing are formed in a cylindrical shape parallel to the axial direction of the rotating shaft member, so the roller bearing can move in the axial direction relative to the rotating shaft member. In response to this, the limiting member limits the movement of the roller bearing in the axial direction.

JP 2014-190517 A

However, in the bearing mechanism of Patent Document 1, the limiting member is fixed to the rotating shaft member and rotates together with the rotating shaft member. Therefore, the rotational speed at which the limiting member and the roller bearing (particularly the rolling elements and the cage) rotate relative to each other is high. As a result, friction between the limiting member and the roller bearing increases, causing the problem that the limiting member is prone to wear.

The present invention provides a bearing mechanism and a reducer that can suppress or prevent wear on the limiting member.

A bearing mechanism according to another aspect of the present invention comprises a rotating shaft member which is cylindrically formed with an outer peripheral surface and has a rib located radially outward from the outer peripheral surface and rotates around an axis, and a retainer which holds a number of cylindrical rolling elements arranged on the outer peripheral surface and whose movement in the axial direction is restricted by the rib, the retainer comprising an annular portion arranged along the outer peripheral surface and a pair of rib portions protruding radially outward from both axial ends of the annular portion, the annular portion having a number of pockets which radially penetrate the annular portion and are arranged at intervals in the radial direction of the annular portion, and into which a number of the rolling elements each enter from the radial outside of the annular portion, the rib portions cover the rolling elements from the axial direction, and a number of the ribs are arranged at intervals in the circumferential direction of the rotating shaft member .

With this configuration, the axial movement of the retainer is limited by the flange of the rotating shaft member. This eliminates the need to attach a separate limiting member to the rotating shaft member. In other words, the limiting member can be excluded from the configuration of the bearing mechanism, preventing wear on the limiting member.

A bearing mechanism according to another aspect of the present invention comprises a rotating shaft member which is cylindrically formed with an outer peripheral surface and has a flange located radially outward from the outer peripheral surface, and a roller bearing having a rolling element unit which includes a plurality of cylindrical rolling elements arranged on the outer peripheral surface and a retainer which holds the plurality of rolling elements, the axial movement of the rotating shaft member being restricted by the flange, the retainer comprising an annular portion arranged along the outer peripheral surface and a pair of flange portions which protrude radially outward from both axial ends of the annular portion, the annular portion having a plurality of pockets which radially penetrate the annular portion and are arranged at intervals in the radial direction of the annular portion, and into which a plurality of the rolling elements each enter from the radial outside of the annular portion, the flange portions cover the rolling elements from the axial direction, and a plurality of the flanges are arranged at intervals in the circumferential direction of the rotating shaft member .

With this configuration, the axial movement of the rolling element unit is limited by the flange of the rotating shaft member. This eliminates the need to attach a separate limiting member to the rotating shaft member. In other words, the limiting member can be excluded from the configuration of the bearing mechanism, preventing wear on the limiting member.

In the above configuration, the flanges may be located on both sides of the rolling element unit in the axial direction.

In the above configuration, the retainer may be divided into a plurality of segments in the circumferential direction of the rotating shaft member.

A bearing mechanism according to another aspect of the present invention comprises a rotating shaft member which is formed in a cylindrical shape having an outer circumferential surface and has a pair of ribs protruding radially outward from the outer circumferential surface at positions spaced from each other in the axial direction, and a roller bearing which includes a rolling element unit which is located between the pair of ribs and whose movement in the axial direction is restricted, the rolling element unit including a retainer having a plurality of cylindrical rolling elements arranged on the outer circumferential surface and a plurality of divided bodies arranged in the circumferential direction of the rotating shaft member to hold the plurality of rolling elements, the retainer having an annular portion arranged along the outer circumferential surface, and a pair of rib portions protruding radially outward from both axial ends of the annular portion, the annular portion having a plurality of pockets which radially penetrate the annular portion and are arranged in the radial direction of the annular portion and into which a plurality of the rolling elements respectively enter from the radial outside of the annular portion, the rib portions covering the rolling elements from the axial direction, and a plurality of the ribs arranged at intervals in the circumferential direction of the rotating shaft member .

With this configuration, the axial movement of the rolling element unit is limited by the flange of the rotating shaft member. This eliminates the need to attach a separate limiting member to the rotating shaft member. In other words, the limiting member can be excluded from the configuration of the bearing mechanism, preventing wear on the limiting member.

The reduction gear according to one aspect of the present invention includes the bearing mechanism, a carrier having an inner circumferential surface through which the rotating shaft member passes and rotatably supporting the rotating shaft member, an outer cylinder positioned inside the carrier so as to be relatively rotatable, and an oscillating gear having an inner circumferential surface through which the rotating shaft member passes and rotatably supporting the rotating shaft member via the roller bearing, which is disposed inside the outer cylinder and oscillatingly rotates with the rotation of the rotating shaft member, and the rotating shaft member is a crankshaft that rotates the outer cylinder and the carrier relatively at a speed slower than the rotational speed of the rotating shaft member based on the oscillating rotation of the oscillating gear.

The above-mentioned bearing mechanism and reducer can suppress or prevent wear on the limiting member.

1 is a cross-sectional view showing a reducer according to a first embodiment of the present invention. 2 is an enlarged cross-sectional view showing a limiting member and its vicinity in the reducer of FIG. 1 . FIG. 4 is an enlarged cross-sectional view showing a main part of a reducer according to a second embodiment of the present invention. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3.

First Embodiment
A first embodiment of the present invention will be described below with reference to FIGS.
1, the reducer 1 according to this embodiment includes an outer cylinder 2, a carrier 3 and an oscillating gear 4 disposed inside the outer cylinder 2, a crankshaft (rotating shaft member) 5 attached to the carrier 3 and the oscillating gear 4, an eccentric portion bearing (roller bearing) 8 interposed between inner peripheral surfaces 41e, 42e of the oscillating gear 4 and the crankshaft 5, and a limiting member 6 attached to the crankshaft 5. The reducer 1 according to this embodiment also includes a crank bearing (small diameter bearing) 7 interposed between inner peripheral surfaces 31e, 32e of the carrier 3 and the crankshaft 5.
The crankshaft 5, the eccentric area bearing 8, the limiting member 6, and the crank bearing 7 constitute a bearing mechanism 100 according to this embodiment. The bearing mechanism 100 limits the movement of the eccentric area bearing 8 in the axial direction of the crankshaft 5 by the limiting member 6.

The outer cylinder 2 is formed in a cylindrical shape centered on the axis C1. The outer cylinder 2 has a plurality of internal teeth 21 on its inner circumference. Specifically, the outer cylinder 2 has a cylindrical main body tube 22 and a plurality of internal tooth pins 23 attached to the inner circumference of the main body tube 22 and arranged at equal intervals in the circumferential direction of the main body tube 22. The internal tooth pins 23 form the aforementioned internal teeth 21. The internal tooth pins 23 are formed in a cylindrical shape with their axis parallel to the axis C1 direction of the outer cylinder 2.

The carrier 3 is located inside the outer cylinder 2. The carrier 3 rotates relatively to the outer cylinder 2 around the axis C1. Specifically, the reducer 1 is equipped with a main bearing B1 arranged between the inner circumference of the outer cylinder 2 and the outer circumference of the carrier 3. Two main bearings B1 are positioned at a distance from each other in the direction of the axis C1. The two main bearings B1 are positioned on both sides of the internal teeth 21 of the outer cylinder 2 in the direction of the axis C1. The main bearings B1 allow relative rotation between the outer cylinder 2 and the carrier 3.

The carrier 3 is configured to sandwich the oscillating gear 4, which will be described later, in the axial direction C1. The carrier 3 includes a first member 31 and a second member 32 aligned in the axial direction C1. The carrier 3 also includes a shaft portion 33 disposed between the first and second members 31, 32 in the axial direction C1. The shaft portion 33 forms a space between the first member 31 and the second member 32 in which the oscillating gear 4 is disposed. A plurality of shaft portions 33 (e.g., three) are arranged at intervals in the circumferential direction of the carrier 3. The shaft portion 33 may be formed integrally with the second member 32 as in the illustrated example, or may be formed integrally with the first member 31, for example.
The first member 31 and the second member 32 are fastened to each other by a fastening member T1 such as a screw. In the illustrated example, the fastening member T1 fastens the first member 31 to a shaft portion 33 formed integrally with the second member 32, but the present invention is not limited thereto.

The carrier 3 has central holes 31a, 32a that penetrate in the direction of the axis C1. The central holes 31a, 32a are formed in the first member 31 and the second member 32, respectively. The central holes 31a, 32a are located in the center portion of the carrier 3 in the radial direction. The central holes 31a, 32a may be holes centered on the axis C1, for example.

The carrier 3 has insertion holes 31b, 32b into which the crankshaft 5 described later is inserted. The insertion holes 31b, 32b are formed in the first member 31 and the second member 32, respectively. The axes of the two insertion holes 31b, 32b formed in the first member 31 and the second member 32 coincide with each other. For example, one of the insertion holes 31b, 32b of the first and second members 31, 32 does not have to penetrate through. In this embodiment, the insertion holes 31b, 32b penetrate through both the first member 31 and the second member 32.

The crankshaft 5 is supported by inner circumferential surfaces 31e, 32e of the insertion holes 31b, 32b of the carrier 3 via crank bearings 7 so as to rotate about its axis.
Specifically, the crankshaft 5 includes first and second journal portions 51, 52. The axes of the first and second journal portions 51, 52 coincide with each other. The first and second journal portions 51, 52 are positioned at a distance from each other in the axial direction of the crankshaft 5. The first journal portion 51 is rotatably supported in the insertion hole 31b of the first member 31. The second journal portion 52 is rotatably supported in the insertion hole 32b of the second member 32.
A portion of the first journal portion 51 protrudes outside the carrier 3 (specifically, outside the outer end portion 31d of the first member 31) in the axial direction of the crankshaft 5. On the other hand, the second journal portion 52 does not protrude outside the carrier 3 in the axial direction (specifically, outside the outer end portion 32d of the second member 32).

The crankshaft 5 also includes an eccentric portion 54 that is eccentric with respect to the first and second journal portions 51 and 52. The eccentric portion 54 is located between the first and second journal portions 51 and 52 in the axial direction of the crankshaft 5. The eccentric portion 54 is disposed in a space between the first member 31 and the second member 32 of the carrier 3. In this embodiment, the eccentric portion 54 includes a first eccentric portion 54A and a second eccentric portion 54B that are aligned in the axial direction. The first and second eccentric portions 54A and 54B are eccentric with respect to each other. The first eccentric portion 54A is located next to the first journal portion 51 in the axial direction of the crankshaft 5. The diameter of the first eccentric portion (large diameter shaft) 54A is larger than the diameter of the first journal portion (small diameter shaft) 51. The second eccentric portion 54B is located next to the second journal portion 52 in the axial direction of the crankshaft 5. The radial dimension of the second eccentric portion (large diameter shaft) 54B is larger than the radial dimension of the second journal portion (small diameter shaft) 52.
The crankshaft 5 configured as above is disposed inside the outer cylinder 2 together with the carrier 3. Although not shown, a plurality of crankshafts 5 (for example, three) are arranged at intervals in the circumferential direction of the carrier 3.

The crank bearing 7 is disposed on the outer periphery of the first and second journal portions 51, 52, respectively. Specifically, the crank bearing 7 (hereinafter referred to as the first crank bearing 71) is located between the insertion hole 31b of the first member 31 of the carrier 3 and the outer periphery of the first journal portion 51. The crank bearing 7 (hereinafter referred to as the second crank bearing 72) is located between the insertion hole 32b of the second member 32 of the carrier 3 and the outer periphery of the second journal portion 52. The crank bearing 7 allows the crank shaft 5 to rotate relative to the carrier 3.

As shown in Fig. 2, the first crank bearing 71 includes a rolling element unit 71a. The rolling element unit 71a includes a plurality of cylindrical rolling elements 71b arranged on the inner peripheral surface 31e of the insertion hole 31b, and a cage 71c that holds the plurality of rolling elements 71b. The plurality of rolling elements 71b are arranged in the circumferential direction of the inner peripheral surface 31e of the insertion hole 31b (the outer peripheral surface of the first journal portion 51). The first crank bearing 71 also includes an annular inner ring 71d arranged radially inward relative to the plurality of rolling elements 71b, and an annular outer ring 71e arranged radially outward relative to the plurality of rolling elements 71b.
The first crank bearing 71 may be, for example, a needle roller bearing in which the axial direction of the rolling elements 71b is parallel to the axial direction of the crankshaft 5. The first crank bearing 71 in this embodiment is a tapered roller bearing in which the axial direction of the rolling elements 71b is inclined with respect to the axial direction of the crankshaft 5.

Although not shown, the configuration of the second crank bearing 72 (see FIG. 1) attached to the outer periphery of the second journal portion 52 is the same as that of the first crank bearing 71 described above. That is, like the first crank bearing 71, the second crank bearing 72 includes a rolling element unit including a plurality of rolling elements 72b and a cage, an inner ring, and an outer ring.

As shown in Figures 1 and 2, a ring-shaped retaining ring 10 is fitted on the inner peripheral surfaces 31e, 32e of the carrier 3 (first and second members 31, 32). The retaining ring 10 faces the crank bearing 7 described above in the axial direction of the crankshaft 5. In this embodiment, the retaining ring 10 faces the outer ring 71e of the crank bearing 7 in the axial direction of the crankshaft 5. This allows the retaining ring 10 to restrict the crank bearing 7 from moving in the axial direction of the crankshaft 5. In particular, the retaining ring 10 is located outside the carrier 3 relative to the crank bearing 7 in the axial direction of the crankshaft 5, preventing the crank bearing 7 from slipping out to the outside of the carrier 3.

As shown in FIG. 1, the oscillating gear 4 is located inside the outer cylinder 2, similar to the carrier 3. The oscillating gear 4 is also located between the first and second members 31, 32 of the carrier 3 in the direction of the axis C1. The oscillating gear 4 rotatably supports the eccentric portion 54 of the crankshaft 5 via the eccentric portion bearing 8. The oscillating gear 4 oscillates and rotates inside the outer cylinder 2 as the crankshaft 5 rotates.

The oscillating gear 4 of this embodiment includes a first oscillating gear 41 attached to a first eccentric portion 54A of the crankshaft 5, and a second oscillating gear 42 attached to a second eccentric portion 54B. The first and second oscillating gears 41, 42 are aligned in the direction of the axis C1 (and in the axial direction of the crankshaft 5 parallel thereto).
The first oscillating gear 41 has a first insertion hole 41a penetrating in the axial direction and into which the first eccentric portion 54A is inserted. The second oscillating gear 42 has a second insertion hole 42a penetrating in the axial direction C1 and into which the second eccentric portion 54B is inserted.

The first and second oscillating gears 41, 42 each have a plurality of external teeth 41b, 42b on their outer circumference. The plurality of external teeth 41b, 42b are arranged in the circumferential direction of the first and second oscillating gears 41, 42. The external teeth 41b, 42b of the first and second oscillating gears 41, 42 mesh with the internal teeth 21 of the outer cylinder 2 described above. The circumferential length of the outer circumference of the first and second oscillating gears 41, 42 is smaller than the circumferential length of the inner circumference of the outer cylinder 2. The number of the external teeth 41b, 42b of the first and second oscillating gears 41, 42 is smaller than the number of the internal teeth 21 of the outer cylinder 2.
The first and second oscillating gears 41, 42 also have central holes 41c, 42c corresponding to the positions of the central holes 31a, 32a of the carrier 3, respectively, and through holes 41d, 42d through which the shaft portion 33 of the carrier 3 passes.

The eccentric portion bearing 8 includes a first eccentric portion bearing 81 located between the outer periphery of the first eccentric portion 54A of the crankshaft 5 and the inner periphery of the first insertion hole 41a of the first oscillating gear 41, and a second eccentric portion bearing 82 located between the outer periphery of the second eccentric portion 54B of the crankshaft 5 and the inner periphery of the second insertion hole 42a of the second oscillating gear 42. The first eccentric portion bearing 81 allows the first eccentric portion 54A to rotate relative to the first oscillating gear 41. The second eccentric portion bearing 82 allows the second eccentric portion 54B to rotate relative to the second oscillating gear 42.

2, the first eccentric portion bearing 81 includes a rolling element unit 81a. The rolling element unit 81a includes a plurality of cylindrical rolling elements 81b arranged on the outer peripheral surface of the first eccentric portion 54A, and a cage 81c that holds the plurality of rolling elements 81b. In addition to the rolling element unit 81a, the first eccentric portion bearing 81 may include, for example, an annular inner ring arranged radially inward relative to the plurality of rolling elements 81b, and an annular outer ring arranged radially outward relative to the plurality of rolling elements 81b.
The rolling elements 81b are aligned in the circumferential direction on the outer circumferential surface of the first eccentric portion 54A. The cage 81c includes an annular portion 81d arranged along the outer circumferential surface of the first eccentric portion 54A, and flange portions 81e protruding radially from both axial ends of the annular portion 81d.

The annular portion 81d has pockets 81f penetrating the annular portion 81d in the radial direction. A plurality of the pockets 81f are arranged at intervals in the circumferential direction of the annular portion 81d. A rolling element 81b is placed in each of the plurality of pockets 81f. In this embodiment, a part of each rolling element 81b enters the pocket 81f from the radially inner side of the annular portion 81d. The remaining part of each rolling element 81b protrudes from the annular portion 81d to the radially inner side.
The flange portions 81e are located on both sides of the rolling elements 81b in the axial direction of the annular portion 81d. Only one of the flange portions 81e is shown in Fig. 2. In this embodiment, the flange portions 81e protrude radially inward from both ends of the annular portion 81d. The flange portions 81e are formed around the entire circumference of the annular portion 81d. As a result, the flange portions 81e cover the multiple rolling elements 81b in the axial direction.

The first eccentric area bearing 81 described above is a needle roller bearing in which the axial direction of the rolling element 81b is parallel to the axial direction of the crankshaft 5. Therefore, the first eccentric area bearing 81 (particularly the rolling element unit 81a) can move in its axial direction relative to the crankshaft 5.

The configuration of the second eccentric region bearing 82 shown in FIG. 1 is the same as that of the first eccentric region bearing 81 described above. That is, the second eccentric region bearing 82, like the first eccentric region bearing 81, has a rolling element unit including a plurality of rolling elements and a cage. In addition, the second eccentric region bearing 82 is a needle roller bearing.

As shown in FIG. 1, the reducer 1 of this embodiment further includes a transmission gear 9 that transmits a driving force to the crankshaft 5 to rotate the crankshaft 5. The attachment position of the transmission gear 9 relative to the crankshaft 5 may be arbitrary. The transmission gear 9 of this embodiment is attached to a first journal portion 51 of the crankshaft 5 located outside the carrier 3 in the direction of the axis C1. The transmission gear 9 rotates around the axis of the first journal portion 51. The transmission gear 9 has a plurality of external teeth 91 on its outer periphery. The external teeth 91 of the transmission gear 9 mesh with an input shaft (not shown) of the motor, etc., so that the transmission gear 9 transmits the driving force of the motor to the crankshaft 5.

In the reducer 1 of this embodiment configured as described above, when the crankshaft 5 rotates upon receiving a driving force from the transmission gear 9, the first and second eccentric portions 54A and 54B rotate eccentrically, causing the first and second oscillating gears 41 and 42 to oscillate relative to the outer cylinder 2 so that the meshing positions between the external teeth 41b and 42b of the first and second oscillating gears 41 and 42 and the internal teeth 21 of the outer cylinder 2 move in the circumferential direction.

In addition, since the first eccentric portion 54A and the second eccentric portion 54B are eccentric to each other, the external teeth 41b of the first oscillating gear 41 and the external teeth 42b of the second oscillating gear 42 mesh with the internal teeth 21 of the outer cylinder 2 at different positions in the circumferential direction. As a result, the first oscillating gear 41 and the second oscillating gear 42 oscillate and rotate in different phases inside the outer cylinder 2.

The oscillating rotation of the first and second oscillating gears 41, 42 is transmitted to the carrier 3 via the crankshaft 5, causing the carrier 3 to rotate around the axis C1 relative to the outer cylinder 2. That is, the outer cylinder 2 and the carrier 3 rotate relatively to each other. This relative rotation speed is slower than the rotation speed of the crankshaft 5. In other words, it is possible to output the rotation of the carrier 3 or the outer cylinder 2 that is slower than the input rotation of the crankshaft 5.

As shown in Fig. 2, the limiting member 6 is formed in an annular shape through which the crankshaft 5 passes. The limiting member 6 is located next to the eccentric portion bearing 8 in the axial direction of the crankshaft 5. The limiting member 6 faces the rolling element unit 81a of the eccentric portion bearing 8 in the axial direction. As a result, the limiting member 6 comes into contact with the rolling element unit 81a to limit the movement of the eccentric portion bearing 8 (particularly the rolling element unit 81a) in the axial direction of the crankshaft 5. The limiting member 6 is disposed so as to be rotatable about the axis of the crankshaft 5 with the crankshaft 5 passing through the limiting member 6.
In this embodiment, the limiting member 6 is formed in an annular shape when viewed from the axial direction of the crankshaft 5. The limiting member 6 is formed in a plate shape with its thickness direction aligned with the axial direction of the crankshaft 5. The limiting member 6 passes through the first journal portion 51 of the crankshaft 5 and is disposed next to the first eccentric portion 54A to which the first eccentric portion bearing 81 is attached.

The inner diameter dimension of the limiting member 6 only needs to be smaller than the diameter dimension of the first eccentric portion 54A and larger than the diameter dimension of the first journal portion 51. As a result, the limiting member 6 overlaps the first eccentric portion 54A from the first journal portion 51 side in the axial direction of the crankshaft 5. In addition, the limiting member 6 is located between the first eccentric portion 54A and the first crank bearing 71 (particularly the inner ring 71d) in the axial direction.
A thickness dimension D1 of the limiting member 6 is larger than a gap dimension D2 between the first eccentric portion 54A and the first crank bearing 71 (particularly the inner ring 71d) in the axial direction of the crankshaft 5. In addition, the inner peripheral edge of the limiting member 6 and the outer peripheral surface of the first journal portion 51 are positioned at a distance from each other in the radial direction of the crankshaft 5. This allows the limiting member 6 to rotate around the axis of the crankshaft 5.
It is more preferable that the difference between the inner diameter dimension of the limiting member 6 and the diameter dimension of the first journal portion 51 is small. In this case, it is possible to suppress or prevent the limiting member 6 from being misaligned in a direction perpendicular to the axial direction with respect to the first journal portion 51 and the first eccentric portion 54A.

The outer diameter of the limiting member 6 is larger than the diameter of the first eccentric portion 54A. The outer peripheral portion of the limiting member 6 protrudes radially outward from the first eccentric portion 54A over the entire circumference of the first eccentric portion 54A. The outer peripheral portion of the limiting member 6 faces the rolling element unit 81a of the first eccentric portion bearing 81 in the axial direction of the crankshaft 5. This limits the axial movement of the first eccentric portion bearing 81 (particularly the rolling element unit 81a) relative to the crankshaft 5. The outer peripheral portion of the limiting member 6 may be opposed and contacted by the cage 81c (particularly the flange portion 81e) of the rolling element unit 81a as illustrated in FIG. 2, or may be opposed and contacted by, for example, the rolling element 81b of the rolling element unit 81a.
The centers of the outer peripheral edge and the inner peripheral edge of the restricting member 6 may be aligned with each other or may be offset from each other.

1, the limiting member 6 is disposed adjacent to the second eccentric portion 54B to which the second eccentric portion bearing 82 is attached, after passing through the second journal portion 52 (see FIG. 1) of the crankshaft 5. In other words, the limiting member 6 is disposed on both sides of the first and second eccentric portions 54A, 54B so as to sandwich the first and second eccentric portions 54A, 54B in the axial direction of the crankshaft 5.
The configuration of the restricting member 6 disposed adjacent to the second eccentric portion 54B is similar to that of the restricting member 6 disposed adjacent to the first eccentric portion 54A.

In this way, in the above-described bearing mechanism 100 and reducer 1, the limiting member 6 rotates relative to the crankshaft 5. That is, the limiting member 6 does not rotate integrally with the crankshaft 5. Therefore, it is possible to keep small the difference between the rotation speed of the limiting member 6 about the axis of the crankshaft 5 and the rotation speed of the rolling element unit 81a (rolling elements 81b and retainer 81c) of the eccentric portion bearing 8 about the same axis. As a result, even if the limiting member 6 and the rolling element unit 81a come into contact with each other, the friction generated between the limiting member 6 and the rolling element unit 81a can be kept small, and wear of the limiting member 6 can be reduced. Therefore, wear of the limiting member 6 can be suppressed.
Furthermore, since wear of the limiting member 6 can be suppressed, the reliability of the bearing mechanism 100 and the reducer 1 can be improved.
The above-mentioned effect is particularly effective when the eccentric portion bearing 8 is a needle roller bearing which is easily movable in the axial direction relative to the crankshaft 5 .

The limiting member 6 passes through the journal portions 51, 52 of the crankshaft 5 and is positioned in the axial direction of the crankshaft 5 between an eccentric portion 54 of the crankshaft 5 having a diameter larger than the journal portions 51, 52, and the crank bearing 7 disposed on the outer periphery of the journal portions 51, 52. This makes it possible to prevent the limiting member 6 from coming off the crankshaft 5 in the axial direction.
In addition, a gap dimension D2 between the eccentric portion 54 of the crankshaft 5 and the crank bearing 7 in the axial direction of the crankshaft 5 is larger than a thickness dimension D1 of the limiting member 6. This allows the limiting member 6 to reliably rotate without being fixed to the crankshaft 5. Therefore, wear of the limiting member 6 can be reliably suppressed.

When the restricting member 6 rotates relative to the crankshaft 5, the inner circumferential portion of the restricting member 6 located between the eccentric portion 54 and the crank bearing 7 in the axial direction of the crankshaft 5 rubs against the eccentric portion 54 and the crank bearing 7. That is, friction occurs between the inner circumferential portion of the restricting member 6 and the eccentric portion 54 and the crank bearing 7. However, the circumferential speed of the inner circumferential portion of the restricting member 6 relative to the crankshaft 5 and the crank bearing 7 is smaller than the circumferential speed of the outer circumferential portion of the restricting member 6 relative to the eccentric portion bearing 8 when the restricting member 6 is fixed to the crankshaft 5 and rotates with the crankshaft 5. Therefore, the wear of the restricting member 6 due to the friction generated between the inner circumferential portion of the restricting member 6 and the eccentric portion 54 or the crank bearing 7 can be suppressed to be smaller than the wear of the restricting member 6 due to the friction generated between the outer circumferential portion of the restricting member 6 and the eccentric portion bearing 8 when the restricting member 6 is fixed to the crankshaft 5. Therefore, in the bearing mechanism 100 of this embodiment, the wear of the restricting member 6 can be suppressed compared to when the restricting member 6 is fixed to the crankshaft 5.

In the eccentric portion bearing 8 of the first embodiment, for example, a part of each rolling element 81b may enter the pocket 81f from the radial outside of the annular portion 81d of the retainer 81c, and the remaining part of each rolling element 81b may protrude radially outward from the annular portion 81d. In this case, the flange portion 81e of the retainer 81c may protrude radially outward from both axial ends of the annular portion 81d, for example.

The crank bearing 7 of the first embodiment may, for example, include only a rolling element unit. In other words, the inner ring and the outer ring of the crank bearing 7 may be formed integrally with, for example, the crankshaft 5 and the carrier 3.

Second Embodiment
Next, a second embodiment of the present invention will be described, focusing on the differences from the first embodiment, mainly with reference to Figures 3 and 4. Note that the same reference numerals are used for the configurations common to the first embodiment, and the description thereof will be omitted.

3, the reducer 1M according to this embodiment includes the same outer cylinder 2 (see FIG. 1) as in the first embodiment, the carrier 3, the oscillating gear 4, the crankshaft (rotating shaft member) 5, and the eccentric portion bearing (roller bearing) 8. The reducer 1M according to this embodiment also includes the same crank bearing 7 as in the first embodiment.
The crankshaft 5 and the eccentric portion bearing 8 constitute a bearing mechanism 100M according to this embodiment. The bearing mechanism 100M restricts the eccentric portion bearing 8 from moving in the axial direction of the crankshaft 5.

The crankshaft 5 is formed in a cylindrical shape having an outer circumferential surface. The crankshaft 5 includes a flange 55M located radially outward from the outer circumferential surface. The flange 55M protrudes radially outward from the outer circumferential surface of the crankshaft 5. For example, a plurality of flanges 55M may be arranged at intervals in the circumferential direction of the crankshaft 5. The flange 55M in this embodiment is formed over the entire circumferential direction of the crankshaft 5. In other words, the flange 55M is formed in an annular shape.
The flange 55M in this embodiment protrudes radially outward from the outer circumferential surface of each eccentric portion 54 (first eccentric portion 54A, second eccentric portion 54B) of the crankshaft 5. The flange 55M faces the eccentric portion bearing 8 (particularly the rolling element units 81a, 82a) located on the outer periphery of each eccentric portion 54 in the axial direction of the crankshaft 5. In this way, the flange 55M restricts the eccentric portion bearing 8 (particularly the rolling element units 81a, 82a) from moving in the axial direction of the crankshaft 5.

Each eccentric portion 54 may have, for example, only one flange 55M. In this case, the flange 55M may protrude radially outward at the end of each eccentric portion 54 located on the first and second journal portions 51, 52 side in the axial direction of the crankshaft 5. This configuration can prevent the eccentric portion bearing 8 (particularly the rolling body units 81a, 82a) from moving in the axial direction of the crankshaft 5 and coming into contact with or hitting the crank bearing 7.

In this embodiment, each eccentric portion 54 has a pair of flanges 55M. The pair of flanges 55M are located at both ends of each eccentric portion 54 in the axial direction of the crankshaft 5. The pair of flanges 55M are located on both sides of the eccentric portion bearing 8 (particularly the rolling body units 81a, 82a) in the axial direction of the crankshaft 5. This prevents the eccentric portion bearing 8 from moving to both sides in the axial direction of the crankshaft 5. Therefore, the eccentric portion bearing 8 can be prevented from hitting the crank bearing 7, and the eccentric portion bearings 8 (first and second eccentric portion bearings 81, 82) adjacent to each other in the axial direction of the crankshaft 5 can also be prevented from hitting each other.

The first eccentric portion bearing 81 of this embodiment is a needle roller bearing including a rolling element unit 81a including a plurality of rolling elements 81b and a cage 81c, as in the first embodiment. Also, as in the first embodiment, the cage 81c includes an annular portion 81d and a pair of flange portions 81e. However, in the rolling element unit 81a of this embodiment, as shown in Figures 3 and 4, a part of each rolling element 81b enters a pocket 81f of the annular portion 81d from the radial outside of the annular portion 81d, and the remaining part of each rolling element 81b protrudes from the annular portion 81d to the radial outside. The flange portions 81e protrude radially outward from both axial ends of the annular portion 81d, and cover the rolling elements 81b from the axial direction.

4, the cage 81c of the first eccentric portion bearing 81 is divided into a plurality of divided bodies 81h in the circumferential direction of the crankshaft 5. Each divided body 81h includes an annular portion 81d and a flange portion 81e, and constitutes a portion of the annular cage 81c in the circumferential direction. The cage 81c can be assembled by joining the plurality of divided bodies 81h to each other.
The material of the cage 81c may be, for example, iron, which has a relatively high strength, but in this embodiment, it is resin, which has a relatively low strength. The number of the segments 81h is not limited to two, and may be, for example, three or more.

As shown in Fig. 3, the second eccentric region bearing 82 of this embodiment is similar to the first eccentric region bearing 81. That is, the second eccentric region bearing 82 is a needle roller bearing equipped with a rolling element unit 82a including a plurality of rolling elements 82b and a cage 82c. In the second eccentric region bearing 82, a part of each rolling element 82b enters a pocket (not shown) of the annular portion 82d of the cage 82c from the radial outside of the annular portion 82d, and the remaining part of each rolling element 82b protrudes from the annular portion 82d to the radial outside. The flange portion 82e of the cage 82c protrudes radially outward from both ends in the axial direction of the annular portion 82d, and covers the rolling elements 82b from the axial direction.
Although not shown, the cage 82c of the second eccentric area bearing 82 is divided into a plurality of segments, similar to the first eccentric area bearing 81. Moreover, the material of the cage 82c in this embodiment is a resin having a relatively low strength.

As described above, the flange portions 81e, 82e of each eccentric portion bearing 8 protrude radially outward from the annular portions 81d, 82d. Therefore, the flanges 55M of each eccentric portion 54 face the retainers 81c, 82c (particularly the flange portions 81e, 82e) in the axial direction of the crankshaft 5. As a result, when the eccentric portion bearing 8 (particularly the rolling body units 81a, 82a) moves in the axial direction of the crankshaft 5 relative to the eccentric portion 54, the retainers 81c, 82c of the eccentric portion bearing 8 come into contact with or hit the flanges 55M.

In the bearing mechanism 100M and reducer 1M of the second embodiment, movement of the eccentric portion bearing 8 (particularly the rolling element units 81a, 82a) in the axial direction of the crankshaft 5 is limited by the flange 55M of the crankshaft 5. This eliminates the need to attach a separate limiting member (for example, the limiting member 6 of the first embodiment) to the crankshaft 5. In other words, the limiting member can be excluded from the configuration of the bearing mechanism 100M to prevent wear of the limiting member.
Furthermore, since wear of the limiting member can be prevented, the reliability of the bearing mechanism 100M and the reducer 1M can be improved.
The above-mentioned effect is particularly effective when the eccentric portion bearing 8 is a needle roller bearing that is easily movable in the axial direction of the crankshaft 5 .

Moreover, the flanges 55M are located on both sides of the eccentric portion bearing 8 (particularly the rolling element units 81a, 82a) in the axial direction of the crankshaft 5. Therefore, the pair of flanges 55M of the crankshaft 5 aligned in the axial direction of the crankshaft 5 can prevent the eccentric portion bearing 8 from moving to both sides in the axial direction relative to the crankshaft 5.
This makes it possible to prevent the retainers 81c, 82c (particularly the flange portions 81e, 82e) of the eccentric portion bearing 8 from colliding with the crank bearing 7 or another eccentric portion bearing 8. It is also possible to prevent the retainers 81c, 82c from colliding with the flange 55M. In other words, it is possible to suppress the application of a large load to the retainers 81c, 82c. Therefore, it is possible to manufacture the retainers 81c, 82c from a resin that is cheaper and has lower strength than iron or the like. As a result, it is possible to reduce the manufacturing costs of the bearing mechanism 100M and the reducer 1M.

The retainers 81c, 82c are divided into multiple segments 81h in the circumferential direction of the crankshaft 5. Therefore, after each of the multiple segments 81h is placed on the outer circumferential surface of the crankshaft 5, the retainers 81c, 82c can be easily placed between a pair of flanges 55M aligned in the axial direction of the crankshaft 5 by simply joining the multiple segments 81h together.

In the eccentric portion bearing 8 of the second embodiment, for example, a part of each rolling element 81b, 82b may enter the pocket 81f of the annular portion 81d, 82d of the retainer 81c, 82c from the radially inner side of the annular portion 81d, 82d, and the remaining part of each rolling element 81b, 82b may protrude radially inward from the annular portion 81d, 82d. Also, the flange portion 81e, 82e of the retainer 81c may protrude radially inward from both axial ends of the annular portion 81d, 82d. In such a configuration, the flange 55M of the eccentric portion 54 may face the rolling elements 81b, 82b in the axial direction of the crankshaft 5. In this case, when the eccentric portion bearing 8 (particularly the rolling body units 81a, 82a) moves in the axial direction of the crankshaft 5 relative to the eccentric portion 54, the rolling bodies 81b, 82b of the eccentric portion bearing 8 come into contact with or hit the flange 55M.

The flange 55M of the second embodiment is not limited to the eccentric portion 54 of the crankshaft 5, but may protrude from, for example, the outer peripheral surfaces of the first and second journal portions 51, 52 of the crankshaft 5. In this case, the flange 55M can limit the movement of the crank bearing 7 (particularly the rolling element units 71a, 72a) located on the outer periphery of the first and second journal portions 51, 52 in the axial direction of the crankshaft 5.

The present invention has been described in detail above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The roller bearing (e.g., eccentric portion bearing 8) of the bearing mechanism according to the present invention may be, for example, a tapered roller bearing in which the axial direction of the rolling elements is inclined relative to the axial direction of the rotating shaft member (e.g., crankshaft 5).

The number of oscillating gears in the reducer of the present invention may be, for example, one, or three or more. Also, the number of eccentric parts on the crankshaft may correspond to the number of oscillating gears.

The bearing mechanism according to the present invention is not limited to use in reducers, but may be used in any machine or device.

1, 1M...reduction gear, 2...outer cylinder, 3...carrier, 4...oscillating gear, 5...crankshaft (rotating shaft member), 6...limiting member, 7...crank bearing (small diameter bearing), 8...eccentric portion bearing (roller bearing), 31...first member, 31e...inner circumferential surface, 32...second member, 32e...inner circumferential surface, 41...first oscillating gear, 41e...inner circumferential surface, 42...second oscillating gear, 42e...inner circumferential surface, 51...first journal portion (small diameter shaft), 52...second journal portion (small diameter shaft), 54...eccentric portion (large diameter shaft), 54A...first eccentric portion (large diameter shaft), 54B...second eccentric portion (large diameter shaft) , 55M... flange, 71... first crank bearing, 71a... rolling body unit, 71b... rolling body, 71c... retainer, 71d... inner ring, 71e... outer ring, 72... second crank bearing, 72a... rolling body unit, 72b... rolling body, 81... first eccentric portion bearing, 81a... rolling body unit, 81b... rolling body, 81c... retainer, 81d... annular portion, 81e... flange portion, 81h... split body, 82... second eccentric portion bearing, 82a... rolling body unit, 82b... rolling body, 82c... retainer, 82d... annular portion, 82e... flange portion, 100, 100M... bearing mechanism

Claims (6)

a rotating shaft member that is formed in a cylindrical shape having an outer circumferential surface, has a flange located radially outward from the outer circumferential surface, and rotates about an axis;
a cage that holds a plurality of cylindrical rolling elements arranged on the outer circumferential surface and whose movement in the axial direction is restricted by the flange,
the cage includes an annular portion disposed along the outer circumferential surface, and a pair of flange portions protruding radially outward from both axial ends of the annular portion,
the annular portion has a plurality of pockets that extend radially through the annular portion, are arranged at intervals in the radial direction of the annular portion, and receive the plurality of rolling elements from the radial outside of the annular portion, respectively;
The flange portion covers the rolling element in the axial direction thereof,
The flange is a bearing mechanism in which a plurality of flanges are arranged at intervals in the circumferential direction of the rotating shaft member . a rotating shaft member formed in a cylindrical shape having an outer circumferential surface and having a flange located radially outward from the outer circumferential surface;
a roller bearing having a rolling element unit including a plurality of cylindrical rolling elements arranged on the outer peripheral surface and a cage for holding the plurality of rolling elements, the rolling element unit being restricted in its axial movement by the flange,
the cage includes an annular portion disposed along the outer circumferential surface, and a pair of flange portions protruding radially outward from both axial ends of the annular portion,
the annular portion has a plurality of pockets that extend radially through the annular portion, are arranged at intervals in the radial direction of the annular portion, and receive the plurality of rolling elements from the radial outside of the annular portion, respectively;
The flange portion covers the rolling element in the axial direction thereof,
The flange is a bearing mechanism in which a plurality of flanges are arranged at intervals in the circumferential direction of the rotating shaft member . The bearing mechanism according to claim 2, wherein the flanges are located on both sides of the rolling element unit in the axial direction. The bearing mechanism according to claim 3, wherein the retainer is divided into a plurality of segments in the circumferential direction of the rotating shaft member. a rotating shaft member formed in a cylindrical shape having an outer circumferential surface, the rotating shaft member having a pair of flanges protruding radially outward from the outer circumferential surface at positions spaced apart from each other in an axial direction;
a roller bearing including a roller unit having a plurality of cylindrical rolling elements arranged on the outer circumferential surface and a plurality of divided bodies arranged in a circumferential direction of the rotating shaft member, the roller unit including a roller unit having a plurality of rolling elements arranged on the outer circumferential surface and a plurality of divided bodies arranged in a circumferential direction of the rotating shaft member and positioned between a pair of the flanges and having a rolling element unit whose movement in the axial direction is restricted,
the cage includes an annular portion disposed along the outer circumferential surface, and a pair of flange portions protruding radially outward from both axial ends of the annular portion,
the annular portion has a plurality of pockets that extend radially through the annular portion, are arranged at intervals in the radial direction of the annular portion, and receive the plurality of rolling elements from the radial outside of the annular portion, respectively;
The flange portion covers the rolling element in the axial direction thereof,
The flange is a bearing mechanism in which a plurality of flanges are arranged at intervals in the circumferential direction of the rotating shaft member . The bearing mechanism according to any one of claims 1 to 5,
a carrier having an inner peripheral surface through which the rotating shaft member passes and rotatably supporting the rotating shaft member;
an outer cylinder that is rotatably disposed inside the carrier;
a roller bearing having an inner circumferential surface through which the rotating shaft member passes and rotatably supporting the rotating shaft member via a roller bearing including the cage, the roller bearing being disposed inside the outer cylinder and configured to oscillate and rotate in association with the rotation of the rotating shaft member;
The rotating shaft member is a crankshaft that rotates the outer cylinder and the carrier relatively at a speed slower than the rotational speed of the rotating shaft member based on the oscillating rotation of the oscillating gear.

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