Bearing mechanism and speed reducer

Abstract

To provide a bearing mechanism which can inhibit or prevent wear of a restriction member, and to provide a speed reducer.SOLUTION: A bearing mechanism 100 includes: a rotary shaft member 5 which rotates around an axis; a roller bearing 8 having a rolling element unit 81a including columnar rolling elements 81b disposed on an outer peripheral surface of the rotary shaft member 5 and a retainer 81c for retaining the rolling elements 81b; and a restriction member 6 which is formed into an annular form through which the rotary shaft member 5 passes, is disposed in such a way so as to be rotatable relative to the rotary shaft member 5, and restricts axial movement of the rolling element unit 81a.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a bearing mechanism and a speed reducer.

Background Art

[0002] Patent Document 1 discloses a bearing mechanism in which a roller bearing (eccentric portion bearing) is disposed on the outer peripheral surface of a rotating shaft member (crankshaft), and a restricting member (washer) is disposed adjacent to the roller bearing in the axial direction of the rotating shaft member. Since the rolling elements of the roller bearing are formed in a columnar shape parallel to the axial direction of the rotating shaft member, the roller bearing can move in the axial direction with respect to the rotating shaft member. In contrast, the restricting member restricts the movement of the roller bearing in the axial direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the bearing mechanism of Patent Document 1, the restricting member is fixed to the rotating shaft member and rotates together with the rotating shaft member. For this reason, the relative rotational speed between the restricting member and the roller bearing (especially the rolling elements and the cage) is high. As a result, the friction generated between the restricting member and the roller bearing increases, and there is a problem that the restricting member is easily worn.

[0005] The present invention provides a bearing mechanism and a speed reducer capable of suppressing or preventing wear of the restricting member.

Means for Solving the Problems

[0013] The bearing mechanism according to another aspect of the present invention includes a rotating shaft member formed in a columnar shape having an outer peripheral surface and having a flange located radially outside the outer peripheral surface and rotating about an axis, and a plurality of columnar rolling elements arranged on the outer peripheral surface and a cage that holds the rolling elements and is restricted from moving in the axial direction by the flange. The cage includes an annular portion arranged along the outer peripheral surface and a pair of flange portions protruding radially outward from both ends in the axial direction of the annular portion. The annular portion has a plurality of pockets that penetrate the annular portion in the radial direction and are arranged at intervals in the radial direction of the annular portion, and the plurality of rolling elements enter from the outside in the radial direction of the annular portion respectively. The flange portion covers the rolling element from its axial direction i. A plurality of the flanges are arranged at intervals in the circumferential direction of the rotary shaft member 。

[0014] By configuring in this way, the movement of the cage in the axial direction is restricted by the flange of the rotating shaft member. As a result, it is not necessary to separately attach a restricting member to the rotating shaft member. That is, the restricting member can be excluded from the configuration of the bearing mechanism to prevent wear of the restricting member.

[0015] The bearing mechanism according to another aspect of the present invention includes a rolling bearing having a rotating shaft member formed in a columnar shape having an outer peripheral surface and having a flange located radially outside the outer peripheral surface, and a plurality of columnar rolling elements arranged on the outer peripheral surface and a cage that holds the plurality of rolling elements and a rolling element unit in which the movement of the rotating shaft member in the axial direction is restricted by the flange. The cage includes an annular portion arranged along the outer peripheral surface and a pair of flange portions protruding radially outward from both ends in the axial direction of the annular portion. The annular portion has a plurality of pockets that penetrate the annular portion in the radial direction and are arranged at intervals in the radial direction of the annular portion, and the plurality of rolling elements enter from the outside in the radial direction of the annular portion respectively. The flange portion covers the rolling element from its axial direction i. A plurality of the flanges are arranged at intervals in the circumferential direction of the rotary shaft member 。

[0016] By configuring in this way, the movement of the rolling element unit in the axial direction is restricted by the flange of the rotary shaft member. As a result, there is no need to separately attach a restricting member to the rotary shaft member. That is, the restricting member can be excluded from the configuration of the bearing mechanism, and wear of the restricting member can be prevented.

[0017] In the above configuration, the flange may be located on both sides of the rolling element unit in the axial direction.

[0018] In the above configuration, the cage may be divided into a plurality of divided bodies in the circumferential direction of the rotary shaft member.

[0019] A bearing mechanism according to another aspect of the present invention includes a rotary shaft member having a pair of flanges formed in a columnar shape with an outer peripheral surface and protruding radially outward from the outer peripheral surface at positions spaced apart from each other in the axial direction, a plurality of columnar rolling elements arranged on the outer peripheral surface, and a cage having a plurality of divided bodies arranged in the circumferential direction of the rotary shaft member and holding the plurality of rolling elements. The rolling element unit is located between the pair of flanges and is restricted in movement in the axial direction. The cage includes an annular portion arranged along the outer peripheral surface, and a pair of flange portions protruding radially outward from both ends in the axial direction of the annular portion. The annular portion has a plurality of pockets that penetrate the annular portion in the radial direction and are arranged at intervals in the radial direction of the annular portion, and the plurality of rolling elements enter from the outside in the radial direction of the annular portion respectively. The flange portion covers the rolling element from its axial direction i. A plurality of the flanges are arranged at intervals in the circumferential direction of the rotary shaft member 。

[0020] By configuring in this way, the movement of the rolling element unit in the axial direction is restricted by the flange of the rotary shaft member. As a result, there is no need to separately attach a restricting member to the rotary shaft member. That is, the restricting member can be excluded from the configuration of the bearing mechanism, and wear of the restricting member can be prevented.

[0021] A speed reducer according to one aspect of the present invention includes the bearing mechanism, 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 relatively rotatable inside the carrier, and a swing gear having an inner peripheral surface through which the rotating shaft member passes and rotatably supporting the rotating shaft member via the roller bearing and disposed inside the outer cylinder and swing-rotating as the rotating shaft member rotates. The rotating shaft member is a crankshaft that relatively rotates the outer cylinder and the carrier at a speed slower than the rotation speed of the rotating shaft member based on the swing rotation of the swing gear.

Effect of the Invention

[0022] In the above-described bearing mechanism and speed reducer, wear of the restricting member can be suppressed or prevented.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0024] 〔First Embodiment〕 Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 2. As shown in Fig. 1, the speed reducer 1 according to the present embodiment includes an outer cylinder 2, a carrier 3 and a swing gear 4 disposed inside the outer cylinder 2, a crankshaft (rotating shaft member) 5 attached to the carrier 3 and the swing gear 4, an eccentric portion bearing (roller bearing) 8 interposed between the inner peripheral surfaces 41e, 42e of the swing gear 4 and the crankshaft 5, and a restricting member 6 attached to the crankshaft 5. Further, the speed reducer 1 of the present embodiment includes a crankshaft bearing (small-diameter bearing) 7 interposed between the inner peripheral surfaces 31e, 32e of the carrier 3 and the crankshaft 5. The crankshaft 5, the eccentric portion bearing 8, the restricting member 6, and the crankshaft bearing 7 constitute a bearing mechanism 100 according to the present embodiment. In the bearing mechanism 100, the restricting member 6 restricts the eccentric portion bearing 8 from moving in the axial direction of the crankshaft 5.

[0025] The outer cylinder 2 is formed in a cylindrical shape centered on the axis C1. The outer cylinder 2 is provided with a plurality of internal teeth 21 on its inner circumference. Specifically, the outer cylinder 2 includes a cylindrical main body cylinder 22 and a plurality of internal tooth pins 23 attached to the inner circumference of the main body cylinder 22 and arranged at equal intervals in the circumferential direction of the main body cylinder 22. The internal tooth pins 23 form the aforementioned internal teeth 21. The internal tooth pins 23 are formed in a cylindrical shape whose axis is parallel to the direction of the axis C1 of the outer cylinder 2.

[0026] The carrier 3 is located inside the outer cylinder 2. The carrier 3 rotates relative to the outer cylinder 2 about the axis C1. Specifically, the speed reducer 1 includes a main bearing B1 disposed between the inner circumference of the outer cylinder 2 and the outer circumference of the carrier 3. The main bearing B1 is located at two positions spaced apart from each other in the direction of the axis C1. The two main bearings B1 are located on both sides of the internal teeth 21 of the outer cylinder 2 in the direction of the axis C1. The main bearing B1 allows relative rotation between the outer cylinder 2 and the carrier 3.

[0027] Carrier 3 is configured to sandwich a swing gear 4, which will be described later, in the direction of axis C1. Carrier 3 includes a first member 31 and a second member 32 arranged in the direction of axis C1. Further, carrier 3 includes a shaft portion 33 disposed between the first and second members 31, 32 in the direction of axis C1. A space for arranging the swing gear 4 is formed between the first member 31 and the second member 32 by the shaft portion 33. A plurality (for example, three) of shaft portions 33 are arranged at intervals in the circumferential direction of carrier 3. The shaft portion 33 may be integrally formed with the second member 32 as shown in the illustrated example, or may be integrally formed 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 shaft portion 33 integrally formed with the first member 31 and the second member 32, but it is not limited to this.

[0028] Carrier 3 has central holes 31a, 32a penetrating in the direction of 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 at the central portion of carrier 3 in the radial direction. The central holes 31a, 32a may be, for example, holes centered on axis C1.

[0029] Carrier 3 has insertion holes 31b, 32b into which a crankshaft 5, which will be 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. One of the insertion holes 31b, 32b of the first and second members 31, 32 does not have to penetrate, for example. The insertion holes 31b, 32b of the present embodiment penetrate both the first member 31 and the second member 32.

[0030] The crankshaft 5 is supported on the inner peripheral surfaces 31e, 32e of the insertion holes 31b, 32b of carrier 3 via a crank bearing 7 so as to rotate about its axis. Specifically, the crankshaft 5 includes first and second journal portions 51 and 52. The axes of the first and second journal portions 51 and 52 coincide with each other. The first and second journal portions 51 and 52 are spaced apart from each other in the axial direction of the crankshaft 5. The first journal portion 51 is rotatably supported with respect to the insertion hole 31b of the first member 31. Also, the second journal portion 52 is rotatably supported with respect to the insertion hole 32b of the second member 32. A part of the first journal portion 51 protrudes outside the carrier 3 in the axial direction of the crankshaft 5 (specifically, outside the outer end portion 31d of the first member 31). 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).

[0031] Further, the crankshaft 5 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 the space between the first member 31 and the second member 32 of the carrier 3. In the eccentric portion 54 of the present embodiment, there are a first eccentric portion 54A and a second eccentric portion 54B arranged 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 adjacent to the first journal portion 51 in the axial direction of the crankshaft 5. The diameter dimension of the first eccentric portion (major axis) 54A is larger than the diameter dimension of the first journal portion (minor axis) 51. The second eccentric portion 54B is located adjacent to the second journal portion 52 in the axial direction of the crankshaft 5. The diameter dimension of the second eccentric portion (major axis) 54B is larger than the diameter dimension of the second journal portion (minor axis) 52. The crankshaft 5 configured as described above is disposed inside the outer cylinder 2 together with the carrier 3. Although not shown, a plurality (for example, three) of the crankshafts 5 are arranged at intervals in the circumferential direction of the carrier 3.

[0032] The crank bearing 7 is disposed on the outer circumferences of the first and second journal portions 51 and 52, respectively. Specifically, the crank bearing 7 (hereinafter referred to as the first crank bearing 71) is positioned between the insertion hole 31b of the first member 31 of the carrier 3 and the outer circumferential surface of the first journal portion 51. Also, the crank bearing 7 (hereinafter referred to as the second crank bearing 72) is positioned between the insertion hole 32b of the second member 32 of the carrier 3 and the outer circumferential surface of the second journal portion 52. The crank bearing 7 permits the rotation of the crankshaft 5 with respect to the carrier 3.

[0033] 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 columnar rolling elements 71b disposed on the inner circumferential 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 circumferential surface 31e (the outer circumferential surface of the first journal portion 51) of the insertion hole 31b. Also, the first crank bearing 71 includes an annular inner ring 71d disposed radially inward with respect to the plurality of rolling elements 71b, and an annular outer ring 71e disposed radially outward with respect 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 element 71b is parallel to the axial direction of the crankshaft 5. The first crank bearing 71 of the present embodiment is a tapered roller bearing in which the axial direction of the rolling element 71b is inclined with respect to the axial direction of the crankshaft 5.

[0034] Although not shown, the configuration of the second crank bearing 72 (see FIG. 1) attached to the outer circumference of the second journal portion 52 is the same as that of the first crank bearing 71 described above. That is, 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, similar to the first crank bearing 71.

[0035] As shown in FIGS. 1 and 2, a ring-shaped retaining ring 10 is fitted on the inner peripheral surfaces 31e and 32e of the carrier 3 (first and second members 31 and 32). The retaining ring 10 faces the above-described crank bearing 7 in the axial direction of the crankshaft 5. In the present embodiment, the retaining ring 10 faces the outer ring 71e of the crank bearing 7 in the axial direction of the crankshaft 5. Thereby, the retaining ring 10 restricts the crank bearing 7 from moving in the axial direction of the crankshaft 5. In particular, since the retaining ring 10 is located outside the carrier 3 with respect to the crank bearing 7 in the axial direction of the crankshaft 5, it prevents the crank bearing 7 from coming out of the outside of the carrier 3.

[0036] As shown in FIG. 1, the oscillating gear 4 is located inside the outer cylinder 2, similarly to the carrier 3. Further, the oscillating gear 4 is located between the first and second members 31 and 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.

[0037] The oscillating gear 4 of the present embodiment includes a first oscillating gear 41 attached to the first eccentric portion 54A of the crankshaft 5 and a second oscillating gear 42 attached to the second eccentric portion 54B. The first and second oscillating gears 41 and 42 are arranged in the direction of the axis C1 (and the axial direction of the crankshaft 5 parallel thereto). The first oscillating gear 41 has a first insertion hole 41a that penetrates 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 that penetrates in the direction of the axis C1 and into which the second eccentric portion 54B is inserted.

[0038] The first and second oscillating gears 41 and 42 each have a plurality of external teeth 41b and 42b on their outer peripheries. The plurality of external teeth 41b and 42b are arranged in the circumferential direction of the first and second oscillating gears 41 and 42. The external teeth 41b and 42b of the first and second oscillating gears 41 and 42 mesh with the internal teeth 21 of the outer cylinder 2 described above. The circumferential length of the outer peripheries of the first and second oscillating gears 41 and 42 is smaller than the circumferential length of the inner periphery of the outer cylinder 2. The number of the external teeth 41b and 42b of the first and second oscillating gears 41 and 42 is smaller than the number of the internal teeth 21 of the outer cylinder 2. The first and second swing gears 41 and 42 each also have central holes 41c and 42c corresponding to the positions of the central holes 31a and 32a of the carrier 3, and through holes 41d and 42d through which the shaft portion 33 of the carrier 3 passes.

[0039] The eccentric portion bearing 8 has a first eccentric portion bearing 81 positioned 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 swing gear 41, and a second eccentric portion bearing 82 positioned 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 swing gear 42. The first eccentric portion bearing 81 allows rotation of the first eccentric portion 54A with respect to the first swing gear 41. The second eccentric portion bearing 82 allows rotation of the second eccentric portion 54B with respect to the second swing gear 42.

[0040] As shown in FIG. 2, the first eccentric portion bearing 81 includes a rolling element unit 81a. The rolling element unit 81a includes a plurality of columnar rolling elements 81b arranged on the outer peripheral surface of the first eccentric portion 54A, and a retainer 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 with respect to the plurality of rolling elements 81b, and an annular outer ring arranged radially outward with respect to the plurality of rolling elements 81b. The plurality of rolling elements 81b are arranged in the circumferential direction of the outer peripheral surface of the first eccentric portion 54A. The retainer 81c includes an annular portion 81d arranged along the outer peripheral surface of the first eccentric portion 54A, and flange portions 81e protruding radially from both axial ends of the annular portion 81d.

[0041] The annular portion 81d has pockets 81f that penetrate the annular portion 81d in the radial direction. A plurality of pockets 81f are arranged at intervals in the circumferential direction of the annular portion 81d. One rolling element 81b enters each of the plurality of pockets 81f. In the present embodiment, a part of each rolling element 81b enters the pocket 81f from the radially inner side of the annular portion 81d. Also, the remaining portion of each rolling element 81b protrudes radially inward from the annular portion 81d. The flange portion 81e is located on both sides of the rolling elements 81b in the axial direction of the annular portion 81d. Only one flange portion 81e is shown in FIG. 2. The flange portion 81e of the present embodiment protrudes radially inward from both ends of the annular portion 81d. The flange portion 81e is formed over the entire circumference of the annular portion 81d. Thereby, the flange portion 81e covers the plurality of rolling elements 81b from its axial direction.

[0042] The above-described first eccentric portion bearing 81 is a needle roller bearing in which the axial direction of the rolling elements 81b is parallel to the axial direction of the crankshaft 5. Therefore, the first eccentric portion bearing 81 (particularly the rolling element unit 81a) can move in the axial direction with respect to the crankshaft 5.

[0043] The configuration of the second eccentric portion bearing 82 shown in FIG. 1 is the same as that of the above-described first eccentric portion bearing 81. That is, the second eccentric portion bearing 82 includes a rolling element unit including a plurality of rolling elements and a cage, similar to the first eccentric portion bearing 81. Further, the second eccentric portion bearing 82 is a needle roller bearing.

[0044] As shown in FIG. 1, the speed reducer 1 of the present 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 with respect to the crankshaft 5 may be arbitrary. The transmission gear 9 of the present embodiment is attached to the 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 about the axis of the first journal portion 51. The transmission gear 9 has a plurality of external teeth 91 on its outer circumference. When the external teeth 91 of the transmission gear 9 mesh with an input shaft (not shown) of a motor or the like, the transmission gear 9 transmits the driving force of the motor to the crankshaft 5.

[0045] In the speed reducer 1 of the present embodiment configured as described above, when the crankshaft 5 rotates by receiving the driving force from the transmission gear 9, the first and second swing gears 41 and 42 swing and rotate with respect to the outer cylinder 2 so that the meshing positions of the external teeth 41b and 42b of the first and second swing gears 41 and 42 and the internal teeth 21 of the outer cylinder 2 move in the circumferential direction due to the eccentric rotation of the first and second eccentric portions 54A and 54B.

[0046] Further, since the first eccentric portion 54A and the second eccentric portion 54B are eccentric with respect 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 with different phases inside the outer cylinder 2.

[0047] Then, when the oscillatory rotation of the first and second oscillating gears 41 and 42 is transmitted to the carrier 3 via the crankshaft 5, the carrier 3 rotates relative to the outer cylinder 2 about the axis C1. That is, the outer cylinder 2 and the carrier 3 rotate relative to each other. This relative rotational speed is slower than the rotational speed of the crankshaft 5. That is, it is possible to output the rotation of the carrier 3 or the outer cylinder 2 decelerated with respect to the input rotation of the crankshaft 5.

[0048] As shown in FIG. 2, the restricting member 6 is formed in an annular shape through which the crankshaft 5 passes. The restricting member 6 is located adjacent to the eccentric portion bearing 8 in the axial direction of the crankshaft 5. The restricting member 6 faces the rolling element unit 81a of the eccentric portion bearing 8 in the axial direction. Thereby, the restricting member 6 restricts the eccentric portion bearing 8 (particularly the rolling element unit 81a) from moving in the axial direction of the crankshaft 5 by contacting the rolling element unit 81a. The restricting member 6 is arranged to be rotatable about its axis with respect to the crankshaft 5 in a state where the crankshaft 5 passes through the restricting member 6. In the present embodiment, the restricting member 6 is formed in an annular shape when viewed from the axial direction of the crankshaft 5. Further, the restricting member 6 is formed in a plate shape with the axial direction of the crankshaft 5 as the thickness direction. The restricting member 6 is arranged adjacent to the first eccentric portion 54A to which the first eccentric portion bearing 81 is attached after passing through the first journal portion 51 of the crankshaft 5.

[0049] The inner diameter dimension of the restricting member 6 only needs to be smaller than at least the diameter dimension of the first eccentric portion 54A and larger than the diameter dimension of the first journal portion 51. Thereby, the restricting member 6 overlaps the first eccentric portion 54A from the first journal portion 51 side in the axial direction of the crankshaft 5. Further, the restricting member 6 is positioned between the first eccentric portion 54A and the first crank bearing 71 (particularly the inner ring 71d) in the axial direction. The thickness dimension D1 of the restricting member 6 is larger than the clearance 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. Also, the inner peripheral edge of the restricting member 6 and the outer peripheral surface of the first journal portion 51 are spaced apart from each other in the radial direction of the crankshaft 5. Thereby, the restricting member 6 can rotate about its axis with respect to the crankshaft 5. It is more preferable that the difference between the inner diameter dimension of the restricting member 6 and the diameter dimension of the first journal portion 51 is smaller. In this case, it is possible to suppress or prevent the restricting member 6 from being displaced in a direction orthogonal to the axial direction with respect to the first journal portion 51 or the first eccentric portion 54A.

[0050] The outer diameter dimension of the restricting member 6 is larger than the diameter dimension of the first eccentric portion 54A. The outer peripheral portion of the restricting member 6 projects outward in the radial direction over the entire circumference of the first eccentric portion 54A. The outer peripheral portion of the restricting member 6 faces the rolling element unit 81a of the first eccentric bearing 81 in the axial direction of the crankshaft 5. Thereby, the outer peripheral portion of the restricting member 6 restricts the axial movement of the first eccentric bearing 81 (particularly the rolling element unit 81a) with respect to the crankshaft 5. The retainer 81c (particularly the flange portion 81e) of the rolling element unit 81a may face and contact the outer peripheral portion of the restricting member 6 as illustrated in FIG. 2, or for example, the rolling element 81b of the rolling element unit 81a may face and contact. The centers of the outer peripheral edge and the inner peripheral edge of the restricting member 6 may coincide with each other or may be offset from each other.

[0051] As shown in FIG. 1, the restricting member 6 is arranged 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. That is, the restricting member 6 is arranged on both sides of the first and second eccentric portions 54A and 54B so as to sandwich the first and second eccentric portions 54A and 54B in the axial direction of the crankshaft 5. The configuration of the restricting member 6 arranged adjacent to the second eccentric portion 54B is the same as that of the above-described restricting member 6 arranged adjacent to the first eccentric portion 54A.

[0052] Thus, in the above-described bearing mechanism 100 and the speed reducer 1, the restricting member 6 rotates relative to the crankshaft 5. That is, the restricting member 6 does not rotate integrally with the crankshaft 5. For this reason, the difference between the rotational speed of the restricting member 6 about the axis of the crankshaft 5 and the rotational speed of the rolling element unit 81a (rolling elements 81b and cage 81c) of the eccentric portion bearing 8 about the same axis can be kept small. Thereby, even if the restricting member 6 comes into contact with the rolling element unit 81a, the friction generated between the restricting member 6 and the rolling element unit 81a can be kept small, and the wear of the restricting member 6 can be reduced. Therefore, the wear of the restricting member 6 can be suppressed. Further, since the wear of the restricting member 6 can be suppressed, the reliability of the bearing mechanism 100 and the speed reducer 1 can be improved. The above-described effect is particularly effective when the eccentric portion bearing 8 is a needle roller bearing that easily moves in the axial direction with respect to the crankshaft 5.

[0053] Further, the restricting member 6 is located between the eccentric portion 54 of the crankshaft 5 having a larger diameter dimension than the journal portions 51 and 52 in the axial direction of the crankshaft 5 after passing through the journal portions 51 and 52 of the crankshaft 5 and the crankshaft bearing 7 arranged on the outer periphery of the journal portions 51 and 52. Thereby, it is possible to prevent the restricting member 6 from coming off the crankshaft 5 in the axial direction. Further, the clearance dimension D2 between the eccentric portion 54 and the crank bearing 7 in the axial direction of the crankshaft 5 is larger than the thickness dimension D1 of the limiting member 6. Thereby, the limiting member 6 can surely rotate without being fixed to the crankshaft 5. Therefore, wear of the limiting member 6 can be surely suppressed.

[0054] When the limiting member 6 rotates with respect to the crankshaft 5, the inner peripheral portion of the limiting 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 peripheral portion of the limiting member 6 and the eccentric portion 54 and the crank bearing 7. However, the peripheral speed of the inner peripheral portion of the limiting member 6 with respect to the crankshaft 5 and the crank bearing 7 is smaller than the peripheral speed of the outer peripheral portion of the limiting member 6 with respect to the eccentric bearing 8 when the limiting member 6 is fixed to the crankshaft 5 and rotates together with the crankshaft 5. For this reason, the wear of the limiting member 6 due to the friction generated between the inner peripheral portion of the limiting member 6 and the eccentric portion 54 and the crank bearing 7 can be suppressed to be smaller than the wear of the limiting member 6 due to the friction generated between the outer peripheral portion of the limiting member 6 and the eccentric bearing 8 when the limiting member 6 is fixed to the crankshaft 5. Therefore, in the bearing mechanism 100 of the present embodiment, wear of the limiting member 6 can be suppressed as compared with the case where the limiting member 6 is fixed to the crankshaft 5.

[0055] In the eccentric bearing 8 of the first embodiment, for example, a part of each rolling element 81b may enter the pocket 81f from the outside in the radial direction of the annular portion 81d of the cage 81c, and the remaining part of each rolling element 81b may protrude from the annular portion 81d to the outside in the radial direction thereof. In this case, the flange portion 81e of the cage 81c may protrude outward in the radial direction from both ends in the axial direction of the annular portion 81d, for example.

[0056] The crank bearing 7 of the first embodiment may include, for example, only a rolling element unit. That is, the inner ring and the outer ring of the crank bearing 7 may be integrally formed with the crankshaft 5 and the carrier 3, for example.

[0057] 〔Second Embodiment〕 Next, regarding the second embodiment of the present invention, mainly with reference to FIGS. 3 to 4, the differences from the first embodiment will be mainly described. For the components common to the first embodiment, the same reference numerals are given, and the description thereof will be omitted.

[0058] As shown in FIG. 3, the speed reducer 1M according to this embodiment includes an outer cylinder 2 (see FIG. 1), a carrier 3, a swing gear 4, a crankshaft (rotating shaft member) 5, and an eccentric portion bearing (roller bearing) 8, which are the same as those in the first embodiment. Further, the speed reducer 1M of this embodiment also includes a crank bearing 7, which is the same as that 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 movement of the eccentric portion bearing 8 in the axial direction of the crankshaft 5.

[0059] The crankshaft 5 is formed in a columnar shape having an outer peripheral surface. The crankshaft 5 includes a flange 55M located radially outward from the outer peripheral surface thereof. The flange 55M projects radially outward from the outer peripheral 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 of this embodiment is formed over the entire circumferential direction of the crankshaft 5. That is, the flange 55M is formed in an annular shape. The flange 55M of this embodiment projects radially outward from the outer peripheral 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. Thereby, the flange 55M restricts the movement of the eccentric portion bearing 8 (particularly the rolling element units 81a, 82a) in the axial direction of the crankshaft 5.

[0060] Each eccentric portion 54 may include, for example, only one flange 55M. In this case, the flange 55M may project radially outward at the end of each eccentric portion 54 located on the first and second journal portions 51, 52 sides in the axial direction of the crankshaft 5. With this configuration, it is possible to prevent the eccentric portion bearing 8 (particularly the rolling element units 81a, 82a) from moving in the axial direction of the crankshaft 5 and contacting or hitting the crank bearing 7.

[0061] In this embodiment, each eccentric portion 54 is provided with 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 element units 81a, 82a) in the axial direction of the crankshaft 5. Thereby, it is possible to prevent the eccentric portion bearing 8 from moving to both sides in the axial direction of the crankshaft 5. Therefore, it is possible to prevent the eccentric portion bearing 8 from hitting the crank bearing 7, and it is also possible to prevent the eccentric portion bearings 8 (the first and second eccentric portion bearings 81, 82) adjacent to each other in the axial direction of the crankshaft 5 from hitting each other.

[0062] 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, similar to the first embodiment. Further, the cage 81c includes an annular portion 81d and a pair of flange portions 81e, similar to the first embodiment. However, in the rolling element unit 81a of this embodiment, as shown in FIGS. 3 and 4, a part of each rolling element 81b enters the pocket 81f of the annular portion 81d from the radially outer side of the annular portion 81d, and the remaining part of each rolling element 81b protrudes from the annular portion 81d to the radially outer side thereof. The flange portion 81e protrudes radially outward from both ends in the axial direction of the annular portion 81d and covers the rolling element 81b from its axial direction.

[0063] Further, as shown in FIG. 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 the annular portion 81d and the flange portion 81e and constitutes a part of the circumferential direction of the annularly formed cage 81c. The cage 81c can be assembled by connecting the plurality of divided bodies 81h to each other. The material of the cage 81c may be, for example, iron having a relatively high strength, but in this embodiment, it is a resin having a relatively low strength. The number of the divided bodies 81h is not limited to two, and may be, for example, three or more.

[0064] As shown in FIG. 3, the second eccentric portion bearing 82 of the present embodiment is the same as the first eccentric portion bearing 81. That is, the second eccentric portion bearing 82 is a needle roller bearing including a rolling element unit 82a including a plurality of rolling elements 82b and a cage 82c. Further, in the second eccentric portion 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 radially outer side of the annular portion 82d of the cage 82c, and the remaining portion of each rolling element 82b protrudes radially outward from the annular portion 82d. The flange portion 82e of the cage 82c protrudes radially outward from both axial ends of the annular portion 82d and covers the rolling elements 82b from its axial direction. Although not shown, the cage 82c of the second eccentric portion bearing 82 is divided into a plurality of divided bodies in the same manner as the cage 81c of the first eccentric portion bearing 81. Further, the material of the cage 82c of the present embodiment is a resin having a relatively low strength.

[0065] As described above, the flange portions 81e and 82e of each eccentric portion bearing 8 protrude radially outward from the annular portions 81d and 82d. For this reason, the flange 55M of each eccentric portion 54 faces the cages 81c and 82c (particularly the flange portions 81e and 82e) in the axial direction of the crankshaft 5. Thereby, when the eccentric portion bearing 8 (particularly the rolling element units 81a and 82a) moves in the axial direction of the crankshaft 5 with respect to the eccentric portion 54, the cages 81c and 82c of the eccentric portion bearing 8 come into contact with or hit the flange 55M.

[0066] In the bearing mechanism 100M and the speed reducer 1M of the second embodiment, the movement of the eccentric portion bearing 8 (particularly the rolling element units 81a and 82a) in the axial direction of the crankshaft 5 is restricted by the flange 55M of the crankshaft 5. Thereby, it is not necessary to separately attach a restricting member (for example, the restricting member 6 of the first embodiment) to the crankshaft 5. That is, the restricting member can be excluded from the configuration of the bearing mechanism 100M, and wear of the restricting member can be prevented. Further, since wear of the restricting member can be prevented, the reliability of the bearing mechanism 100M and the speed reducer 1M can be improved. The above-described effect is particularly effective when the eccentric portion bearing 8 is a needle roller bearing that easily moves in the axial direction with respect to the crankshaft 5.

[0067] Also, the flanges 55M are located on both sides of the eccentric portion bearing 8 (especially the rolling element units 81a, 82a) in the axial direction of the crankshaft 5. Therefore, the pair of flanges 55M of the crankshaft 5 arranged in the axial direction of the crankshaft 5 can prevent the eccentric portion bearing 8 from moving to both sides in the axial direction with respect to the crankshaft 5. Thereby, it is possible to prevent the cages 81c, 82c (especially the flange portions 81e, 82e) of the eccentric portion bearing 8 from colliding with the crank bearing 7 or another eccentric portion bearing 8. Also, it is possible to prevent the cages 81c, 82c from colliding with the flanges 55M. That is, it is possible to suppress a large load from acting on the cages 81c, 82c. Therefore, the cages 81c, 82c can be manufactured from a resin that is less expensive and has lower strength than iron or the like. As a result, it is possible to reduce the manufacturing cost of the bearing mechanism 100M and the speed reducer 1M.

[0068] Also, the cages 81c, 82c are divided into a plurality of divided bodies 81h in the circumferential direction of the crankshaft 5. Therefore, after arranging the plurality of divided bodies 81h on the outer peripheral surface of the crankshaft 5 respectively, the cages 81c, 82c can be easily arranged between the pair of flanges 55M arranged in the axial direction of the crankshaft 5 by simply connecting the plurality of divided bodies 81h to each other.

[0069] In the eccentric portion bearing 8 of the second embodiment, for example, a part of each of the rolling elements 81b, 82b may enter the pockets 81f of the annular portions 81d, 82d from the radially inner side of the annular portions 81d, 82d of the cages 81c, 82c, and the remaining portions of the rolling elements 81b, 82b may protrude radially inward from the annular portions 81d, 82d. Also, the flange portions 81e, 82e of the cage 81c may protrude radially inward from both axial ends of the annular portions 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 (especially the rolling element units 81a, 82a) moves in the axial direction of the crankshaft 5 with respect to the eccentric portion 54, the rolling elements 81b, 82b of the eccentric portion bearing 8 come into contact with or hit the flange 55M.

[0070] The flange 55M of the second embodiment is not limited to the eccentric portion 54 of the crankshaft 5, and may protrude from the outer peripheral surfaces of the first and second journal portions 51 and 52 of the crankshaft 5, for example. In this case, the flange 55M can restrict the movement of the crankshaft bearings 7 (particularly the rolling element units 71a and 72a) located on the outer periphery of the first and second journal portions 51 and 52 in the axial direction of the crankshaft 5.

[0071] Although the details of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

[0072] The roller bearing (for example, the eccentric portion bearing 8) of the bearing mechanism according to the present invention may be a tapered roller bearing in which the axial direction of the rolling elements is inclined with respect to the axial direction of the rotating shaft member (for example, the crankshaft 5), for example.

[0073] The number of oscillating gears in the speed reducer of the present invention may be, for example, one, or may be three or more. Also, the number of eccentric portions on the crankshaft only needs to correspond to the number of oscillating gears.

[0074] The bearing mechanism according to the present invention is not limited to being applied to a speed reducer, and may be applied to any machine or device.

Explanation of Reference Numerals

[0075] 1,1M... Reducer, 2... Outer cylinder, 3... Carrier, 4... Oscillating gear, 5... Crankshaft (rotating shaft member), 6... Limiting member, 7... Crankshaft bearing (small-diameter bearing), 8... Eccentric part bearing (roller bearing), 31... First member, 31e... Inner peripheral surface, 32... Second member, 32e... Inner peripheral surface, 41... First oscillating gear, 41e... Inner peripheral surface, 42... Second oscillating gear, 42e... Inner peripheral surface, 51... First journal part (small-diameter shaft), 52... Second journal part (small-diameter shaft), 54... Eccentric part (large-diameter shaft), 54A... First eccentric part (large-diameter shaft), 54B... Second eccentric part (large-diameter shaft), 55M... Flange, 71... First crankshaft bearing, 71a... Rolling element unit, 71b... Rolling element, 71c... Retainer, 71d... Inner ring, 71e... Outer ring, 72... Second crankshaft bearing, 72a... Rolling element unit, 72b... Rolling element, 81... First eccentric part bearing, 81a... Rolling element unit, 81b... Rolling element, 81c... Retainer, 81d... Annular part, 81e... Flange part, 81h... Split body, 82... Second eccentric part bearing, 82a... Rolling element unit, 82b... Rolling element, 82c... Retainer, 82d... Annular part, 82e... Flange part, 100, 100M... Bearing mechanism

Claims

1. A rotating shaft member formed in a columnar shape having an outer peripheral surface, having a flange located radially outward from the outer peripheral surface, and rotating about an axis; A cage that holds a plurality of columnar rolling elements arranged on the outer peripheral surface and is restricted from moving in the axial direction by the flange. The cage includes an annular portion arranged along the outer peripheral surface, and a pair of flange portions protruding radially outward from both ends in the axial direction of the annular portion. The annular portion has a plurality of pockets that penetrate the annular portion in the radial direction and are arranged at intervals in the radial direction of the annular portion, and the plurality of rolling elements enter from the outside in the radial direction of the annular portion respectively. The flange portion covers the rolling element from its axial direction. The flange is a bearing mechanism in which a plurality are arranged at intervals in the circumferential direction of the rotating shaft member.

2. A rotating shaft member formed in a columnar shape having an outer peripheral surface, having a flange located radially outward from the outer peripheral surface; A roller bearing including a plurality of columnar rolling elements arranged on the outer peripheral surface and a cage that holds the plurality of rolling elements, and having a rolling element unit in which movement in the axial direction of the rotating shaft member is restricted by the flange. The cage includes an annular portion arranged along the outer peripheral surface, and a pair of flange portions protruding radially outward from both ends in the axial direction of the annular portion. The annular portion has a plurality of pockets that penetrate the annular portion in the radial direction and are arranged at intervals in the radial direction of the annular portion, and the plurality of rolling elements enter from the outside in the radial direction of the annular portion respectively. The flange portion covers the rolling element from its axial direction. The flange is a bearing mechanism in which a plurality are arranged at intervals in the circumferential direction of the rotating shaft member.

3. The flange is the bearing mechanism according to claim 2, located on both sides of the rolling element unit in the axial direction.

4. The cage is the bearing mechanism according to claim 3, which is divided into a plurality of divided bodies in the circumferential direction of the rotating shaft member.

5. A rotating shaft member formed in a columnar shape having an outer peripheral surface, and having a pair of flanges protruding radially outward from the outer peripheral surface at positions spaced apart from each other in the axial direction; A roller bearing including a plurality of columnar rolling elements arranged on the outer peripheral surface and a cage having a plurality of divided bodies arranged in the circumferential direction of the rotating shaft member and holding the plurality of rolling elements, and having a rolling element unit located between the pair of flanges and restricted from moving in the axial direction. The retainer includes an annular portion arranged along the outer peripheral 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 penetrate the annular portion in the radial direction and are arranged at intervals in the radial direction of the annular portion, and the plurality of rolling elements enter from the outside in the radial direction of the annular portion respectively. The flange portion covers the rolling element from its axial direction. The bearing is a bearing mechanism in which a plurality of the same are arranged at intervals in the circumferential direction of the rotary shaft member.

6. The bearing mechanism according to any one of Claims 1 to 5, a carrier having an inner peripheral surface through which the rotary shaft member passes and rotatably supporting the rotary shaft member, an outer cylinder that is relatively rotatable inside the carrier, a swing gear that has an inner peripheral surface through which the rotary shaft member passes, rotatably supports the rotary shaft member via a roller bearing including the retainer, is arranged inside the outer cylinder, and swings and rotates as the rotary shaft member rotates. The rotary shaft member is a speed reducer that is a crankshaft that relatively rotates the outer cylinder and the carrier at a speed slower than the rotation speed of the rotary shaft member based on the swing rotation of the swing gear.

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