CN111911523A

CN111911523A - Bearing mechanism and speed reducer

Info

Publication number: CN111911523A
Application number: CN202010259567.6A
Authority: CN
Inventors: 镰形州一
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2019-05-10
Filing date: 2020-04-03
Publication date: 2020-11-10
Anticipated expiration: 2040-04-03
Also published as: CN111911523B; JP7301638B2; JP2020186812A

Abstract

The invention provides a bearing mechanism and a speed reducer. The bearing mechanism of the present invention includes: a roller bearing having a plurality of cylindrical rolling elements and a cage for holding the plurality of rolling elements; and a restricting member that contacts the rolling elements of the roller bearing, thereby restricting movement of the roller bearing in an axial direction.

Description

Bearing mechanism and speed reducer

Technical Field

The present invention relates to a bearing mechanism and a speed reducer.

Background

Patent document 1 discloses a bearing mechanism in which a roller bearing (crank bearing) is disposed on an inner peripheral surface of a base member (carrier), and a restricting member is provided on a portion of the inner peripheral surface located near the roller bearing in the axial direction.

Since the rolling elements of the roller bearing are formed in a cylindrical shape extending in the axial direction of the inner peripheral surface, the roller bearing moves in the axial direction of the inner peripheral surface with respect to the base member. In contrast, the restricting member restricts the axial movement of the roller bearing.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional bearing mechanism, only the cage of the roller bearing that holds the plurality of rolling elements abuts against the restricting member, and therefore, there is a problem that the load is concentrated on the cage.

The invention provides a bearing mechanism and a speed reducer which can alleviate the concentration of load to a retainer and protect the retainer.

Means for solving the problems

A bearing mechanism according to an aspect of the present invention includes: a roller bearing having a plurality of cylindrical rolling elements and a cage for holding the plurality of rolling elements; and a restricting member that contacts the rolling elements of the roller bearing, thereby restricting movement of the roller bearing in an axial direction.

With this configuration, when the roller bearing is pressed against the restricting member in the axial direction, at least the restricting member contacts the rolling elements. Therefore, as compared with the case where the restricting member is in contact with only the retainer, the load acting on the retainer in accordance with the pressing of the roller bearing against the restricting member can be reduced. That is, the concentration of the load on the cage of the roller bearing can be alleviated.

In the above configuration, the bearing mechanism may include a base member having an inner circumferential surface, and the plurality of rolling elements may be disposed on the inner circumferential surface.

In the above-described configuration, the rolling elements may be formed in a cylindrical shape extending in an axial direction of the inner peripheral surface and arranged in a circumferential direction of the inner peripheral surface, the restricting member may be attached to a portion of the inner peripheral surface located beside the roller bearing in the axial direction, and the restricting member may be in contact with the rolling elements in the axial direction.

The roller bearing including the rolling elements described above is easily moved in the axial direction of the inner peripheral surface with respect to the base member and is easily pressed against the restricting member, but the rolling elements of the roller bearing contact the restricting member as described above, so that concentration of the load on the cage of the roller bearing can be effectively alleviated.

In the above configuration, the holder may include: an annular portion disposed along the inner peripheral surface; and a flange portion protruding in a radial direction from both ends in an axial direction of the ring-shaped portion, the flange portion being located on both sides of the rolling element in the axial direction, the restricting member including: a body portion attached to the inner peripheral surface; and a contact protrusion protruding from an opposing surface of the body portion that faces the roller bearing in the axial direction and contacting the rolling element, wherein a protruding length of the contact protrusion in the axial direction is greater than a thickness of the brim in the axial direction.

With this configuration, even if the contact convex portion (tip end) of the restricting member contacts the rolling element of the roller bearing in the axial direction, the overhang portion of the cage, which is disposed between the main body portion of the restricting member and the rolling element in the axial direction, can be suppressed or prevented from contacting the main body portion of the restricting member. Thus, the retainer can be protected more reliably.

In the above configuration, the holder may include: an annular portion disposed along the inner peripheral surface; and a flange portion protruding in a radial direction from both ends in an axial direction of the annular portion and located on both sides of the rolling element in the axial direction, wherein the restricting member has a housing recess recessed from an end surface facing the roller bearing side in the axial direction and housing the flange portion.

With this configuration, the end surface of the restricting member can be brought into contact with the rolling elements of the roller bearing in a state where the brim portion of the cage, which is disposed between the restricting member and the rolling elements in the axial direction, is accommodated in the accommodating recess portion of the restricting member. Thereby, even if the restricting member contacts the roller bearing in the axial direction, the contact of the eaves portion of the retainer with the restricting member can be suppressed or prevented. Thus, the retainer can be protected more reliably.

In the above configuration, the holder may include: an annular portion disposed along the inner peripheral surface; and eaves which protrude from both ends in the axial direction of the ring-shaped portion in the radial direction and are positioned on both sides of the rolling elements in the axial direction, wherein a length in the radial direction of a first eaves of the eaves, which is axially arranged between the restricting member and the rolling elements, is smaller than a length in the radial direction of a second eaves of the eaves, which axially positions the rolling elements between the second eaves and the first eaves.

With this configuration, the area of the rolling elements covered by the first eaves in the axial direction becomes smaller. That is, the region of the rolling element facing the restricting member without interposing the first flange therebetween in the axial direction is increased. This ensures a region of the rolling element that contacts the restricting member, and the restricting member can stably contact the rolling element.

A bearing mechanism according to another aspect of the present invention includes: a base member having an inner peripheral surface; a roller bearing having: a plurality of rolling elements that are formed in a cylindrical shape extending in an axial direction of the inner circumferential surface and are arranged in a circumferential direction of the inner circumferential surface; and a holder, which includes: an annular portion disposed along the inner peripheral surface; and eaves which protrude from both ends in the axial direction of the ring-shaped portion in the radial direction and are positioned on both sides of the rolling elements in the axial direction, and the cage holds the plurality of rolling elements, and a length in the radial direction of a first eaves in the eaves of the cage is smaller than a length in the radial direction of a second eaves in the eaves, the second eaves positioning the rolling elements between the second eaves and the first eaves in the axial direction; and a restricting member having: a body attached to a portion of the inner circumferential surface located axially beside the roller bearing such that the first flange is located axially between the body and the rolling elements; and a contact protrusion protruding from an opposing surface of the body portion opposing the roller bearing in the axial direction and contacting the rolling element, wherein a protruding length of the contact protrusion in the axial direction is larger than a thickness of the brim in the axial direction, and the restricting member contacts the rolling element to restrict movement of the roller bearing in the axial direction.

With this configuration, when the roller bearing is pressed against the restricting member in the axial direction, the contact convex portion of the restricting member contacts the rolling element. Therefore, as compared with the case where the restricting member is in contact with only the retainer, the load acting on the retainer in accordance with the pressing of the roller bearing against the restricting member can be reduced. That is, the concentration of the load on the cage of the roller bearing can be alleviated.

A speed reducer according to an aspect of the present invention includes: the bearing mechanism; a rotating shaft rotatably supported by the inner circumferential surface via the roller bearing; an outer cylinder, the base member being disposed inside the outer cylinder so as to be rotatable relative to the outer cylinder; and a swing gear disposed inside the outer cylinder and configured to swing and rotate with rotation of the rotating shaft. The rotation shaft is a crankshaft that relatively rotates the outer cylinder and the base member at a speed slower than a rotation speed of the rotation shaft based on the swing rotation of the swing gear.

With this configuration, the speed reducer includes the bearing mechanism capable of protecting the retainer of the roller bearing, and therefore, the reliability of the speed reducer can be improved.

A bearing mechanism according to another aspect of the present invention includes: a roller bearing having a plurality of cylindrical rolling elements and a cage for holding the plurality of rolling elements; a restricting member that contacts the rolling elements of the roller bearing, thereby restricting movement of the roller bearing in an axial direction; and a rotating shaft having an outer peripheral surface, wherein the plurality of rolling elements are disposed on the outer peripheral surface.

In the above configuration, the rolling elements may be formed in a cylindrical shape extending in an axial direction of the rotary shaft and arranged in a circumferential direction of the outer peripheral surface, the restricting member may be formed in a ring shape through which the rotary shaft passes, may be attached to a portion of the outer peripheral surface located near the roller bearing in the axial direction, and may be in contact with the rolling elements in the axial direction.

In the above configuration, the holder may include: an annular portion disposed along the outer peripheral surface; and a flange portion that protrudes in the radial direction from both ends in the axial direction of the annular portion, is located on both sides of the rolling element in the axial direction, and forms a gap between an outer peripheral edge of the restricting member and an inner edge of the flange portion when viewed in the axial direction.

In the above configuration, the holder may include: an annular portion disposed along the outer peripheral surface; and a collar portion protruding in a radial direction from both ends in an axial direction of the ring-shaped portion and located on both sides of the rolling element in the axial direction, wherein the restricting member is disposed so that the rolling element is located between the restricting member and one collar portion in the axial direction, and an interval in the axial direction between the restricting member and the one collar portion is smaller than an interval in the axial direction between the collar portions.

In the above configuration, the rotary shaft may include: a large-diameter shaft portion having an outer peripheral surface to which the roller bearing is attached; and a small-diameter shaft portion that is located near the large-diameter shaft portion in the axial direction and has a smaller diameter than the large-diameter shaft portion, the bearing mechanism including a small-diameter bearing disposed on an outer periphery of the small-diameter shaft portion, and the restriction member being fixed by being sandwiched between the large-diameter shaft portion and the small-diameter bearing in the axial direction.

A bearing mechanism according to another aspect of the present invention includes: a rotating shaft having: a large-diameter shaft portion having an outer peripheral surface; and a small-diameter shaft portion located axially beside the large-diameter shaft portion, the small-diameter shaft portion having a smaller diameter than the large-diameter shaft portion; a small-diameter bearing disposed on an outer periphery of the small-diameter shaft portion; a roller bearing having: a plurality of rolling elements that are formed in a cylindrical shape extending in an axial direction of the rotating shaft and are arranged in a circumferential direction of the outer circumferential surface; and a holder, which includes: an annular portion disposed along the outer peripheral surface; and a flange portion that protrudes in a radial direction from both ends in an axial direction of the ring-shaped portion, and is positioned on both sides of the rolling elements in the axial direction, and the cage holds the plurality of rolling elements; and a restricting member having: a body portion formed in an annular shape through which the small-diameter shaft portion of the rotary shaft passes, and fixed by being interposed between the large-diameter shaft portion and the small-diameter bearing in an axial direction; and a contact protrusion that protrudes in an axial direction from an outer peripheral portion of the main body portion that protrudes outward in the radial direction from the large-diameter shaft portion toward the roller bearing and contacts the rolling element, wherein the restricting member is disposed such that the rolling element is located between the restricting member and one of the eaves portions in the axial direction, a gap between the restricting member and the one of the eaves portions in the axial direction is smaller than a gap between the eaves portions in the axial direction, and a gap is formed between the restricting member and an inner edge of the other of the eaves portions in the axial direction, and the restricting member contacts the rolling element to restrict movement of the roller bearing in the axial direction.

A reduction gear according to another aspect of the present invention includes: the bearing mechanism; a carrier having an inner circumferential surface through which the rotary shaft passes, the carrier rotatably supporting the rotary shaft; an outer cylinder, inside of which the carrier is disposed to be rotatable relative to the outer cylinder; and a swing gear having an inner circumferential surface through which the rotation shaft passes, the swing gear being rotatably supported by the roller bearing, the swing gear being disposed inside the outer cylinder and being configured to swing in accordance with rotation of the rotation shaft, the rotation shaft being a crankshaft that relatively rotates the outer cylinder and the carrier at a speed slower than a rotation speed of the rotation shaft in accordance with the swing rotation of the swing gear.

ADVANTAGEOUS EFFECTS OF INVENTION

In the bearing mechanism and the speed reducer, the concentration of the load on the retainer of the roller bearing can be alleviated to protect the retainer.

Drawings

Fig. 1 is a sectional view showing a reduction gear according to a first embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view showing a portion of the first restricting member and its vicinity in the reduction gear of fig. 1.

Fig. 3 is an enlarged cross-sectional view showing the first restriction member of fig. 2 and a portion in the vicinity thereof.

Fig. 4 is an enlarged cross-sectional view showing a main portion of a reduction gear according to a second embodiment of the present invention.

Fig. 5 is a sectional view taken along line V-V of fig. 4.

Description of the reference numerals

1. 1M, a speed reducer; 2. an outer cylinder; 3. a carrier (base member); 4. a swing gear; 5. a crankshaft (rotating shaft); 6. a restraining member; 7. crankshaft bearings (roller bearings); 7M, crankshaft bearings (small diameter bearings); 8. eccentric portion bearings (roller bearings); 10M, a restraining member; 10Ma, outer perimeter; 10Mc, a main body portion; 10Md, contact protrusion; 31. a first member; 31e, an inner peripheral surface; 31f, an internal thread portion; 31h, a radial support portion; 32. a second member; 32e, an inner peripheral surface; 32f, an internal thread portion; 32h, a radial support portion; 51. a first journal portion (small diameter shaft portion); 52. a second journal portion (small diameter shaft portion); 54. an eccentric portion (large diameter shaft portion); 54A, a first eccentric portion (large diameter shaft portion); 54B, a second eccentric portion (large diameter shaft portion); 61. a first restriction member; 61a, an external thread portion; 61d, a main body portion; 61e, contact convex part; 61f, opposite face; 61h, a housing recess; 61i, end faces; 62. a second restricting member; 62a, an external thread part; 62e, contact convex part; 71. a first crankshaft bearing; 71a, rolling elements; 71b, a holder; 71c, an annular portion; 71d, eave portion; 71d1, first eave; 71d2, second eave; 72. a second crankshaft bearing; 72a, rolling bodies; 81. a first eccentric portion bearing; 82. a second eccentric portion bearing; 82a, rolling bodies; 82b, a retainer; 82c, an annular portion; 82d, eave portion; 82d1, one eave; 82d2, the other eave; 82f, inner edge; 100. 100M, bearing mechanism.

Detailed Description

[ first embodiment ]

Hereinafter, a first embodiment of the present invention will be described with reference to fig. 1 to 3.

As shown in fig. 1, a speed reducer 1 of the present embodiment includes: an outer cylinder 2; a carrier (base member) 3 and a swing gear 4 which are disposed inside the outer cylinder 2; a crankshaft (rotating shaft) 5 attached to the carrier 3 and the oscillating gear 4; a crankshaft bearing (roller bearing) 7 interposed between the inner

circumferential surfaces

31e and 32e of the carrier 3 and the crankshaft 5; and a regulating member 6 attached to the carrier 3.

The carrier 3, the crank bearing 7, and the restriction member 6 constitute a bearing mechanism 100 of the present embodiment. The bearing mechanism 100 is a mechanism that restricts the axial movement of the crankshaft bearing 7 by the restricting 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 periphery. Specifically, the outer cylinder 2 includes: a cylindrical main body tube part 22; and a plurality of inner pins 23 attached to the inner periphery of the main body tube portion 22 and arranged at equal intervals in the circumferential direction of the main body tube portion 22. The internal tooth pins 23 constitute the aforementioned internal teeth 21. The inner pin 23 is formed in a cylindrical shape extending in the direction of the axis C1 of the outer cylinder 2.

The carrier 3 is disposed inside the outer tube 2. The carrier 3 is relatively rotatable with respect to the outer cylinder 2 about an axis C1. Specifically, the speed reducer 1 includes a main bearing B1 provided between the inner periphery of the outer tube 2 and the outer periphery of the carrier 3. The two main bearings B1 are provided at intervals in the direction of the axis C1. The two main bearings B1 are located on both sides of the outer cylinder 2 in the direction of the axis C1 of the internal teeth 21. The main bearing B1 allows relative rotation between the outer tube 2 and the carrier 3.

The carrier 3 is configured to sandwich the swing gear 4, which will be described later, in the direction of the axis C1. The carrier 3 has a first member 31 and a second member 32 aligned in the direction of the axis C1. The carrier 3 further includes a shaft portion 33 disposed between the first member 31 and the second member 32 in the direction of the axis C1. A space for disposing the swing gear 4 is formed between the first member 31 and the second member 32 by the shaft portion 33. A plurality of (for example, three) shaft portions 33 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 shown 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 together by a fastening member T1 such as a screw.

In the illustrated example, the fastening member T1 fastens the first member 31 and the shaft portion 33 integrally formed with the second member 32, but is not limited thereto.

The carrier 3 has

center holes

31a and 32a penetrating in the direction of the axis C1.

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 radially central portion of the carrier 3. The

central holes

31a, 32a may be holes centered, for example, on the axis C1.

The carrier 3 has

insertion holes

31b, 32b into which the crankshafts 5 discussed later are inserted.

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 member 31 and the second member 32 may not penetrate therethrough. The insertion holes 31b, 32b of the present embodiment penetrate both the first member 31 and the second member 32.

Inner

circumferential surfaces

31e, 32e of the

insertion holes

31b, 32b are formed in a circular shape as viewed in the axial direction. The inner

peripheral surfaces

31e, 32e of the

insertion holes

31b, 32b have

female screw portions

31f, 32 f. The

female screw portions

31f, 32f are formed at portions of the

insertion holes

31b, 32b near the ends in the axis C1 direction of the carrier 3. Specifically, the

female screw portions

31f, 32f are formed on

outer end portions

31d, 32d of the first member 31 and the second member 32, respectively, which are located on the outer sides in the arrangement direction of the first member 31 and the second member 32.

Further, the inner

peripheral surfaces

31e, 32e of the

insertion holes

31b, 32b have stepped

portions

31g, 32g and

radial support portions

31h, 32 h. The stepped

portions

31g, 32g are surfaces facing the outside of the carrier 3 in the direction of the axis C1. The

radial bearing portions

31h, 32h are faces that radially support the crankshaft 5 discussed later. The

radial support portions

31h and 32h have an inner diameter smaller than the inner diameter of the

female screw portions

31f and 32 f. The first member 31 has a step portion 31g and a radial support portion 31h, and the second member 32 has a step portion 32g and a radial support portion 32 h.

The

female screw portions

31f, 32f, the

step portions

31g, 32g, and the

radial support portions

31h, 32h are arranged from both end portions (

outer end portions

31d, 32d) in the direction of the axis line C1 of the carrier 3 toward the inside of the carrier 3 in the order of the

female screw portions

31f, 32f, the

step portions

31g, 32g, and the

radial support portions

31h, 32 h. Specifically, the female screw portion 31f, the step portion 31g, and the radial support portion 31h of the first member 31 are arranged in order of the female screw portion 31f, the step portion 31g, and the radial support portion 31h from the outer end 31d toward the inner end 31c of the first member 31. The female screw portion 32f, the step portion 32g, and the radial support portion 32h formed in the second member 32 are arranged in the order of the female screw portion 32f, the step portion 32g, and the radial support portion 32h from the outer end 32d toward the inner end 32c of the second member 32.

The crankshaft 5 is rotatably supported by the inner

circumferential surfaces

31e, 32e of the

insertion holes

31b, 32b of the carrier 3 via a crankshaft bearing 7.

Specifically, the crankshaft 5 has a first journal portion 51 and a second journal portion 52. The axis of the first journal portion 51 and the axis of the second journal portion 52 coincide with each other. The first journal portion 51 and the second journal portion 52 are located at positions spaced apart from each other in the axial direction of the crankshaft 5. The first journal portion 51 is rotatably supported by the radial support portion 31h of the insertion hole 31b of the first member 31. In addition, the second collar portion 52 is rotatably supported by the radial support portion 32h of the insertion hole 32b of the second member 32.

The crankshaft 5 has a small diameter portion 53 having a smaller diameter than the first journal portion 51 and the second journal portion 52. The axis of the small diameter portion 53 coincides with the axes of the first and

second journal portions

51 and 52. The small diameter portion 53 extends in the axial direction from the first journal portion 51 such that the first journal portion 51 is located between the small diameter portion 53 and the second journal portion 52 in the axial direction of the crankshaft 5. A part of the small diameter portion 53 is located on the outer side in the axial direction of the carrier 3 (specifically, on the outer side of the outer end portion 31d of the first member 31). The small diameter portion 53 may be omitted, and for example, a part of the first journal portion 51 may extend to the outside in the axial direction of the carrier 3.

The crankshaft 5 has an eccentric portion 54 eccentric with respect to the first journal portion 51, the second journal portion 52, and the small diameter portion 53. The eccentric portion 54 is located between the first journal portion 51 and the second journal portion 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. The eccentric portion 54 of the present embodiment has a first eccentric portion 54A and a second eccentric portion 54B that are arranged in the axial direction. The first eccentric portion 54A and the second eccentric portion 54B are eccentric to each other.

The crankshaft 5 configured as described above is disposed inside the outer cylinder 2 together with the carrier 3.

Although not shown, a plurality of (for example, three) crankshafts 5 are arranged at intervals in the circumferential direction of the carrier 3.

The crank bearings 7 are disposed on the inner

circumferential surfaces

31e, 32e of the

insertion holes

31b, 32b of the carrier 3. Specifically, the crank bearing 7 (hereinafter, referred to as a first crank bearing 71) is disposed between the radial support portion 31h of the insertion hole 31b of the first member 31 and the first journal portion 51. The crank bearing 7 (hereinafter, referred to as a second crank bearing 72) is disposed between the radial support portion 32h of the insertion hole 32b of the second member 32 and the second journal portion 52. The crankshaft bearing 7 allows rotation of the crankshaft 5 relative to the carrier 3.

As shown in fig. 2, the first crank bearing 71 includes: a plurality of cylindrical rolling elements 71a disposed on the radial support portion 31h (inner circumferential surface 31e) of the insertion hole 31 b; and a cage 71b that holds the plurality of rolling elements 71 a.

The plurality of rolling elements 71a are arranged in the circumferential direction of the radial support portion 31h (inner circumferential surface 31e) of the insertion hole 31 b. The plurality of rolling elements 71a are each formed in a cylindrical shape extending in the axial direction of the radial support portion 31 h. That is, the first crank bearing 71 is a needle roller bearing in which the axial direction of the rolling element 71a is parallel to the axis of the radial support portion 31 h. Therefore, the first crank bearing 71 is easily moved in the axial direction of the insertion hole 31b with respect to the carrier 3.

The holder 71b has: an annular portion 71c arranged along the inner peripheral surface of the radial support portion 31h (inner peripheral surface 31e) of the insertion hole 31 b; and a brim portion 71d that protrudes in the radial direction from both ends in the axial direction of the annular portion 71 c.

The annular portion 71c is formed with a recess 71e that penetrates the annular portion 71c in the radial direction. A plurality of the recesses 71e are arranged at intervals in the circumferential direction of the annular portion 71 c. One rolling element 71a is placed in each of the plurality of pockets 71 e. A part of each rolling element 71a enters the recess 71e from the radially inner side of the annular portion 71 c. The remaining portion of each rolling element 71a projects radially inward from the annular portion 71 c.

The eaves 71d are located on both sides of the rolling elements 71a in the axial direction of the ring 71 c. The brim portion 71d protrudes radially inward from both ends of the annular portion 71 c. The brim portion 71d is formed over the entire circumference of the ring portion 71 c. Thereby, the eaves 71d axially cover the rolling elements 71 a.

The brim portion 71d has: a first eaves portion 71d1 disposed axially on one side of the outer end 31d of the first member 31; and a second eaves portion 71d2 disposed axially on one side of the inboard end 31c of the first member 31. The radial length D1 of the first brim portion 71D1 extending in the radial direction from the annular portion 71c is smaller than the radial length D2 of the second brim portion 71D 2. Therefore, the area of the rolling body 71a covered by the first eaves 71d1 is smaller than the area of the rolling body 71a covered by the second eaves 71d 2.

Although not shown, the second crank bearing 72 (see fig. 1) attached to the insertion hole 32b of the second member 32 has the same configuration as the first crank bearing 71 described above. That is, the second crank bearing 72 has a plurality of rolling elements 72a and a cage for holding the plurality of rolling elements 72a, similarly to the first crank bearing 71. The retainer includes an annular portion similar to the first crank bearing 71, and a first brim portion and a second brim portion provided at both ends of the annular portion in the axial direction.

As shown in fig. 1, the oscillating gear 4 is disposed inside the outer tube 2, similarly to the carrier 3. The swing gear 4 is disposed between the first member 31 and the second member 32 of the carrier 3 in the direction of the axis C1.

The oscillating gear 4 is attached to an eccentric portion 54 of the crankshaft 5 via an eccentric portion bearing 8. The oscillating gear 4 oscillates and rotates inside the outer cylinder 2 in accordance with the rotation of the crankshaft 5.

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 swing gear 41 and the second swing gear 42 are aligned in the direction of the axis C1.

A first insertion hole 41a is formed in the first oscillating gear 41 to penetrate in the direction of the axis C1 and into which the first eccentric portion 54A is inserted. The speed reducer 1 includes a first eccentric portion bearing 81 provided between the outer periphery of the first eccentric portion 54A and the inner periphery of the first insertion hole 41 a. The first eccentric portion bearing 81 allows rotation of the first eccentric portion 54A relative to the first swing gear 41.

A second insertion hole 42a is formed in the second swing gear 42 to pass through in the direction of the axis C1 and into which the second eccentric portion 54B is inserted. The reduction gear 1 includes a second eccentric portion bearing 82 provided between the outer periphery of the second eccentric portion 54B and the inner periphery of the second insertion hole 42 a. The second eccentric portion bearing 82 allows rotation of the second eccentric portion 54B relative to the second swing gear 42.

The first eccentric portion bearing 81 and the second eccentric portion bearing 82 are roller bearings similar to the crank bearing 7. That is, the first eccentric portion bearing 81 and the second eccentric portion bearing 82 have a plurality of rolling elements that are formed in a cylindrical shape and are arranged in the circumferential direction. The axial direction of the rolling elements is parallel to the axis of the crankshaft 5. Therefore, the first eccentric portion bearing 81 and the second eccentric portion bearing 82 are movable in the axial direction of the first insertion hole 41a and the second insertion hole 42a with respect to the first swing gear 41 and the second swing gear 42, similarly to the crank bearing 7. The crankshaft 5 is also movable in the axial direction with respect to the carrier 3, the first oscillating gear 41, and the second oscillating gear 42.

The first and second oscillating gears 41, 42 have a plurality of

external teeth

41b, 42b on the outer peripheries, respectively. The plurality of

external teeth

41b, 42b are arranged in the circumferential direction. 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. The circumferential lengths of the outer peripheries of the first and second swing gears 41 and 42 are smaller than the circumferential length of the inner periphery of the outer cylinder 2. The number of the external teeth 41b of the first rocking gear 41 and the external teeth 42b of the second rocking gear 42 is smaller than the number of the internal teeth 21 of the outer cylinder 2.

The first and second oscillating gears 41 and 42 are respectively provided with

center holes

41c and 42c corresponding to the positions of the center 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.

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 mounting position of the transmission gear 9 on the crankshaft 5 may be arbitrary. In the present embodiment, the transmission gear 9 is attached to the small diameter portion 53 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 small diameter portion 53. The transmission gear 9 has a plurality of external teeth 91 on the outer periphery. The external teeth 91 of the transmission gear 9 mesh with an input shaft (not shown) of the motor, and the transmission gear 9 transmits the driving force of the motor to the crankshaft 5.

In the reduction gear 1 of the present embodiment configured as described above, when the crankshaft 5 receives the driving force from the transmission gear 9 and rotates, the first oscillating gear 41 and the second oscillating gear 42 oscillate and rotate with respect to the outer cylinder 2 so that the meshing positions of the external teeth 41B and 42B of the first oscillating gear 41 and the second oscillating gear 42 and the internal teeth 21 of the outer cylinder 2 move in the circumferential direction due to the eccentric rotation of the first eccentric portion 54A and the second eccentric portion 54B.

Further, 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 positions different from each other in the circumferential direction. Thereby, the first and second oscillating gears 41 and 42 oscillate and rotate in different phases from each other inside the outer cylinder 2.

The oscillating rotation of the first oscillating gear 41 and the second oscillating gear 42 is transmitted to the carrier 3 via the crankshaft 5, and the carrier 3 rotates about the axis C1 with respect to the outer cylinder 2. That is, the outer cylinder 2 and the carrier 3 rotate relatively. The relative rotational speed is slower than the rotational speed of the crankshaft 5. That is, the rotation of the carrier 3 or the outer cylinder 2 can be output after being decelerated with respect to the input rotation of the crankshaft 5.

As shown in fig. 1, the restricting member 6 is attached to portions of the inner

circumferential surfaces

31e, 32e of the

insertion holes

31b, 32b of the carrier 3, which portions are located near the crank bearing 7 in the axial direction. The restriction member 6 of the present embodiment has

male screw portions

61a, 62a that engage with the

female screw portions

31f, 32f of the

insertion holes

31b, 32 b. That is, the regulating member 6 is attached to the insertion holes 31b and 32b of the carrier 3 by engaging the external threaded

portions

61a and 62a with the internal threaded

portions

31f and 32f of the carrier 3.

In a state where the restriction member 6 is attached to the carrier 3, the restriction member 6 axially faces the crank bearing 7. The restricting member 6 contacts the rolling

bodies

71a, 72a of the crankshaft bearing 7, thereby restricting the axial movement of the crankshaft bearing 7. Further, the restricting member 6 also faces the crankshaft 5 in the axial direction, and therefore, also restricts the movement of the crankshaft 5 in the axial direction.

The restricting member 6 has a first restricting member 61 and a second restricting member 62 disposed adjacent to both ends in the axial direction of the portion of the crankshaft 5 other than the small diameter portion 53. The first and

second restriction members

61 and 62 sandwich the crankshaft 5 from the axial direction. Thereby, the first and

second restriction members

61 and 62 can restrict the movement of the crankshaft 5 in the axial direction.

The first restriction member 61 is formed in a circular shape as viewed in the axial direction of the crankshaft 5. As shown in fig. 1 and 2, the first restriction member 61 is attached to the first member 31 of the carrier 3 and is disposed near the first crank bearing 71 and the first journal portion 51 in the axial direction. Therefore, the first restriction member 61 is formed with a through hole 61c that penetrates the first restriction member 61 in the axial direction and through which the small diameter portion 53 of the crankshaft 5 passes.

The outer peripheral portion of the first restriction member 61 in the radial direction is in contact with the step portion 31g of the insertion hole 31b of the first member 31. Thereby, the first restriction member 61 is positioned with respect to the first member 31 in the axial direction.

In this state, as shown in fig. 2, the first eaves 71d1 of the first crank bearing 71 are disposed between the first restriction member 61 and the rolling elements 71a in the axial direction. The second lip 71d2 of the first crank bearing 71 is disposed such that the rolling elements 71a are positioned between the second lip 71d2 and the first lip 71d1 in the axial direction.

As shown in fig. 2 and 3, the first restriction member 61 has a main body portion 61d attached to the insertion hole 31b (inner circumferential surface 31e) of the first member 31, and a contact protrusion 61e protruding from the main body portion 61 d.

The contact protrusion 61e protrudes from the opposing surface 61f of the main body portion 61d that faces the first eaves portion 71d1 of the first crank bearing 71 in the axial direction. The contact protrusion 61e is located radially inward of the first eaves 71d 1. Thereby, the contact convex portion 61e can contact the rolling element 71a of the first crank bearing 71. The projection length L1 in the axial direction of the contact projection 61e is larger than the thickness T1 in the axial direction of the first eaves 71d 1. Thus, even if the contact convex portion 61e of the first restriction member 61 contacts the rolling element 71a of the first crank bearing 71, the main body portion 61d of the first restriction member 61 does not contact the rolling element 71 a.

The contact convex portion 61e of the present embodiment also protrudes from a surface 61g of the body portion 61d that faces the first journal portion 51 of the crankshaft 5 in the axial direction. In fig. 2 and 3, the surface 61g of the body portion 61d facing the first journal portion 51 is located closer to the first journal portion 51 than the facing surface 61f of the body portion 61d in the axial direction, but the present invention is not limited to this. The contact convex portion 61e may not protrude from the surface 61g of the body portion 61d facing the first journal portion 51, for example.

In addition, the contact convex portion 61e of the present embodiment is formed in the entire circumferential direction of the first restriction member 61. Thereby, the contact convex portion 61e contacts the plurality of rolling elements 71a of the first crank bearing 71 arranged in the circumferential direction. Further, for example, a plurality of contact convex portions 61e may be arranged in the circumferential direction of the first restriction member 61.

The arithmetic mean roughness Ra of the surface of the first restriction member 61 that contacts the rolling elements 71a of the first crank bearing 71, that is, the surface of the contact convex portion 61e, is preferably 0.8 μm or less, for example. The hardness of the contact convex portion 61e is preferably equal to or higher than the hardness of the rolling element 71a of the first crank bearing 71 (for example, equal to or higher than 58 HRC). In order to reduce the surface roughness of the contact convex portion 61e or to increase the hardness of the contact convex portion 61e, the first restriction member 61 (particularly, the contact convex portion 61e) may be subjected to polishing treatment, heat treatment, or the like. By reducing the surface roughness of the contact convex portion 61e or increasing the hardness of the contact convex portion 61e, it is possible to suppress wear of the contact convex portion 61e that is in contact with the rolling element 71 a.

The first restriction member 61 of the present embodiment has a housing recess 61h that houses the first eaves portion 71d1 of the first crank bearing 71. The housing recess 61h is recessed from an end surface 61i of the first restriction member 61 in the axial direction toward the first crank bearing 71 side. The receiving recess 61h is formed by a difference in level between the opposing surface 61f of the body portion 61d and the end surface 61i of the first regulating member 61 constituting the contact convex portion 61 e.

Although not shown, the second restriction member 62 (see fig. 1) attached to the insertion hole 32b of the second member 32 has the same configuration as the first restriction member 61 described above. That is, the second restriction member 62 has a body portion and a contact convex portion 62e that protrudes from the body portion and contacts the rolling elements 72a of the second crankshaft bearing 72, similarly to the first restriction member 61. In addition, the second restriction member 62 has a housing recess that houses the first brim of the second crank bearing 72.

The second restricting member 62 of the present embodiment is a member common to the first restricting member 61. Therefore, although the through hole 62c that penetrates the second restriction member 62 in the axial direction is also formed in the second restriction member 62, the present invention is not limited to this.

In this way, in the bearing mechanism 100 and the reduction gear 1 described above, the restriction member 6 that restricts the axial movement of the crank bearing 7 is in contact with the rolling

elements

71a, 72a of the crank bearing 7. Therefore, when the crankshaft bearing 7 is pressed against the restricting member 6 in the axial direction, at least the restricting member 6 contacts the rolling

elements

71a, 72 a. Therefore, as compared with the case where the restricting member 6 is in contact with only the retainer 71b of the crank bearing 7, the load acting on the retainer 71b as the crank bearing 7 is pressed against the restricting member 6 can be reduced. Therefore, the concentration of the load on the retainer 71b of the crank bearing 7 can be alleviated, and the retainer 71b can be protected. Further, since the crankshaft bearing 7 can be protected, the reliability of the bearing mechanism 100 and the reduction gear 1 can be improved.

The above-described effect is particularly effective in the case where the crank bearing 7 is a needle roller bearing that is easy to move in the axial direction of the insertion hole 31b with respect to the carrier 3.

In addition, the restricting member 6 has: a body portion 61d attached to the insertion holes 31b and 32b (inner

circumferential surfaces

31e and 32e) of the carrier 3; and contact

convex portions

61e, 62e that protrude from the body portion 61d and contact the rolling

elements

71a, 72a of the crank bearing 7. The protruding length of the

contact protrusions

61e and 62e in the axial direction is larger than the thickness of the brim 71d of the retainer 71b in the axial direction. Therefore, even if the contact

convex portions

61e, 62e of the restricting member 6 contact the rolling

elements

71a, 72a, the contact of the first eaves 71d1 of the cage 71b, which is axially disposed between the main body 61d of the restricting member 6 and the rolling

elements

71a, 72a, with the main body 61d of the restricting member 6 can be suppressed or prevented. Thus, the holder 71b can be protected more reliably.

The restricting member 6 has a receiving recess 61h that is recessed from the end surface 61i facing the crankshaft bearing 7 in the axial direction and receives the first eaves 71d1 of the retainer 71 b. Therefore, the end surface 61i of the restricting member 6 can be brought into contact with the rolling

elements

71a, 72a of the crank bearing 7 in a state where the first eaves portion 71d1 of the cage 71b, which is disposed between the restricting member 6 and the rolling

elements

71a, 72a in the axial direction, is accommodated in the accommodating recess 61h of the restricting member 6. Thereby, even if the restricting member 6 contacts the crankshaft bearing 7 in the axial direction, the first eaves portion 71d1 of the retainer 71b can be suppressed or prevented from contacting the restricting member 6. Thus, the holder 71b can be protected more reliably.

Further, of the eaves 71D located on both sides of the rolling

bodies

71a and 72a in the crank bearing 7, the radial length D1 of the first eaves 71D1 disposed between the restricting member 6 and the rolling

bodies

71a and 72a in the axial direction is smaller than the radial length D2 of the second eaves 71D2, and the rolling

bodies

71a and 72a are located between the second eaves 71D2 and the first eaves 71D1 in the second eaves 71D 2. Therefore, the area of the rolling

elements

71a, 72a covered by the first eaves 71d1 in the axial direction becomes small. That is, the region of the rolling

elements

71a and 72a facing the restricting member 6 in the axial direction without interposing the first eaves 71d1 therebetween is increased. This ensures the contact areas of the rolling

elements

71a and 72a with the restricting member 6, and enables the contact

convex portions

61e and 62e (or the end surface 61i) of the restricting member 6 to stably contact the rolling

elements

71a and 72 a.

In the first crank bearing 71 according to the first embodiment, for example, a part of each rolling element 71a may enter the recess 71e from the radially outer side of the annular portion 71c of the retainer 71b, and the remaining part of each rolling element 71a may protrude from the annular portion 71c to the radially outer side thereof. In this case, the brim portion 71d of the retainer 71b may protrude outward in the radial direction from both ends in the axial direction of the annular portion 71c, for example. The second crank bearing 72 may be configured similarly to the first crank bearing 71, for example.

In the crank bearing 7 of the first embodiment, for example, the axial direction of the rolling

elements

71a and 72a may be inclined with respect to the axis of the radial support portion 31 h. That is, the crankshaft bearing 7 may be, for example, a tapered roller bearing.

In the bearing mechanism and the speed reducer according to the first embodiment, the restriction member may not have the external thread portion, and may be attached to the carrier by being fitted into an inner peripheral surface of an insertion hole of the carrier, for example.

[ second embodiment ]

Next, a second embodiment of the present invention will be described mainly with reference to fig. 4 to 5, focusing on differences from the first embodiment. Note that the same reference numerals are given to the same components as those of the first embodiment, and the description thereof is omitted.

As shown in fig. 4, a speed reducer 1M of the present embodiment includes an outer cylinder 2 (see fig. 1), a carrier 3, a swing gear 4, and a crankshaft (rotating shaft) 5, as in the first embodiment. Further, the speed reducer 1M of the present embodiment includes an eccentric portion bearing (roller bearing) 8 interposed between the inner

circumferential surfaces

41e and 42e of the oscillating gear 4 and the crankshaft 5, and a restricting member 10M attached to the crankshaft 5, as in the first embodiment. Further, the speed reducer 1M of the present embodiment includes a crankshaft bearing (small diameter bearing) 7M interposed between the inner peripheral surface 32e of the carrier 3 and the crankshaft 5, as in the first embodiment.

The crankshaft 5, the eccentric portion bearing 8, the regulating member 10M, and the crankshaft bearing 7M constitute a bearing mechanism 100M of the present embodiment. The bearing mechanism 100M is a mechanism for restricting the movement of the eccentric portion bearing 8 in the axial direction by the restricting member 10M.

In the present embodiment, the inner peripheral surface 32e of the insertion hole 32b of the second member 32 of the carrier 3 into which the crankshaft 5 is inserted has an annular recessed portion 32j recessed from the inner peripheral surface 32e and extending in the circumferential direction, instead of the female screw portion 32f (see fig. 1) as in the first embodiment. An annular retainer ring 6M that restricts axial movement of the crank bearing 7M disposed on the inner peripheral surface 32e of the second member 32 is fitted into the annular recess 32 j.

Although not shown, the insertion hole 31b (see fig. 1) of the first member 31 of the carrier 3 may be configured similarly to the insertion hole 32b of the second member 32 described above. That is, a retainer ring may be fitted into the insertion hole 31b of the first member 31 instead of the restricting member 6 (see fig. 1) of the first embodiment.

The crankshaft bearing 7M disposed on the inner peripheral surface 32e of the second member 32 allows rotation of the crankshaft 5 with respect to the carrier 3, as in the first embodiment. The crank bearing 7M of the present embodiment includes: a plurality of cylindrical rolling elements 7Ma arranged along the circumferential direction of the inner circumferential surface 32 e; a cage 7Mb that holds the plurality of rolling elements 7 Ma; an annular inner ring 7Mc disposed radially inward of the plurality of rolling elements 7 Ma; and an annular outer ring 7Md disposed radially outward of the plurality of rolling elements 7 Ma. The crank bearing 7M may be, for example, a needle roller bearing in which the axial direction of the rolling element 7Ma is parallel to the axis C2 of the inner circumferential surface 32e of the second member 32, or a tapered roller bearing in which the axial direction of the rolling element 7Ma is inclined with respect to the axis C2 of the inner circumferential surface 32e in the present embodiment.

The crankshaft 5 has a second journal portion (small diameter shaft portion) 52 and a second eccentric portion (large diameter shaft portion) 54B located beside the second journal portion 52, as in the first embodiment. The second collar portion 52 has a smaller diameter dimension than the second eccentric portion 54B. The axis C2 of the second journal portion 52 is parallel to the axis C3 of the second eccentric portion 54B, but at an offset position from each other. The outer periphery of the second journal portion 52 is located radially inward of the outer periphery of the second eccentric portion 54B. The aforementioned crank bearing 7M is disposed on the outer periphery of the second journal portion 52. A second eccentric portion bearing 82 (eccentric portion bearing 8) is attached to the outer peripheral surface of the second eccentric portion 54B.

Although not shown, the relationship between the first journal portion 51 and the first eccentric portion 54A constituting the crankshaft 5 is the same as the relationship between the second journal portion 52 and the second eccentric portion 54B described above (see fig. 1 and 2).

The second eccentric portion bearing 82 has: a plurality of cylindrical rolling elements 82a disposed on the outer peripheral surface of the second eccentric portion 54B; and a cage 82b that holds the plurality of rolling elements 82 a.

The plurality of rolling elements 82a are arranged in the circumferential direction of the outer peripheral surface of the second eccentric portion 54B. The plurality of rolling elements 82a are each formed in a cylindrical shape extending in the axial direction of the second eccentric portion 54B. That is, the second eccentric portion bearing 82 is a needle roller bearing in which the axial direction of the rolling element 82a is parallel to the axis C3 of the second eccentric portion 54B. Therefore, the second eccentric portion bearing 82 is easily moved in the axial direction thereof with respect to the second eccentric portion 54B.

The holder 82b has: an annular portion 82c disposed along the outer peripheral surface of the second eccentric portion 54B; and a brim portion 82d that protrudes in the radial direction from both ends in the axial direction of the annular portion 82 c.

The annular portion 82c has a plurality of recesses 82e, and the plurality of recesses 82e penetrate the annular portion 82c in the radial direction and are arranged in the circumferential direction of the annular portion 82 c. One rolling element 82a is disposed in each of the plurality of pockets 82 e. A part of each rolling element 82a enters the recess 82e from the radially inner side of the annular portion 82 c. The remaining portion of each rolling element 82a projects radially inward from the annular portion 82 c.

The eaves 82d are located on both sides of the rolling elements 82a in the axial direction of the ring 82 c. The brim 82d protrudes radially inward from both ends of the annular portion 82 c. As shown in fig. 5, the brim portion 82d is formed over the entire circumference of the ring portion 82 c. That is, the brim 82d is formed in a ring shape (annular shape) as viewed in the axial direction. The eaves 82d axially covers the rolling elements 82 a. However, a part of each rolling element 82a protrudes radially inward from the inner edge 82f of the rim 82 d.

As shown in fig. 4, the first eccentric portion bearing 81 attached to the outer peripheral surface of the first eccentric portion 54A has the same structure as the second eccentric portion bearing 82 described above. That is, the first eccentric portion bearing 81 includes a plurality of rolling elements and a cage that holds the plurality of rolling elements. The retainer further includes an annular portion and eaves portions provided at both ends of the annular portion in the axial direction.

As shown in fig. 4 and 5, the restricting member 10M is formed in a ring shape through which the crankshaft 5 passes. The restricting member 10M is attached to a portion of the outer peripheral surface of the crankshaft 5 located beside the eccentric portion bearing 8 in the axial direction. The restricting member 10M is axially opposed to and in contact with the rolling elements 82a of the eccentric portion bearing 8.

In the present embodiment, the restriction member 10M is formed in an annular shape as viewed in the axial direction. The restricting member 10M is disposed near the second eccentric portion 54B to which the second eccentric portion bearing 82 is attached after the second journal portion 52 of the crankshaft 5 passes.

The inner diameter of the restricting member 10M may be smaller than the diameter of the second eccentric portion 54B and larger than the diameter of the second collar portion 52. Thus, the regulating member 10M is disposed so as to overlap the second eccentric portion 54B from the second journal portion 52 side in the axial direction. The restriction member 10M is fixed by being sandwiched between the second eccentric portion 54B and the crank bearing 7M in the axial direction. Specifically, the restricting member 10M is axially sandwiched and fixed between the second eccentric portion 54B and the inner ring 7Mc of the crankshaft bearing 7M.

It is more preferable that the difference between the inner diameter dimension of the restriction member 10M and the diameter dimension of the second collar portion 52 is small. In this case, the displacement of the restricting member 10M relative to the second journal portion 52 and the second eccentric portion 54B in the direction orthogonal to the axial direction can be suppressed or prevented.

The outer diameter dimension of the restriction member 10M is larger than the diameter dimension of the second eccentric portion 54B. Therefore, the outer peripheral portion of the restricting member 10M protrudes outward in the radial direction of the second eccentric portion 54B. The outer peripheral portion of the regulating member 10M is axially opposed to and in contact with the rolling bodies 82a of the second eccentric portion bearing 82. Thereby, the restricting member 10M restricts the movement of the second eccentric portion bearing 82 in the axial direction with respect to the crankshaft 5.

The outer peripheral edge 10Ma of the restriction member 10M is eccentric with respect to the inner peripheral edge 10 Mb. Therefore, in a state where the second collar portion 52 is inserted through the restriction member 10M, the center of the inner peripheral edge 10Mb of the restriction member 10M can be aligned with the axis C2 of the second collar portion 52. Further, the center of the outer peripheral edge 10Ma of the restricting member 10M can be made coincident with the axis C3 of the second eccentric portion 54B. Further, the outer peripheral portion of the regulating member 10M can be made to project outward of the second eccentric portion 54B over the entire circumference of the second eccentric portion 54B.

As shown in fig. 4, the regulating member 10M (particularly, the outer peripheral portion) is disposed such that the rolling elements 82a are positioned between the regulating member 10M and one eaves 82d1, and the one eaves 82d1 is an eaves positioned on the first eccentric portion 54A side in the axial direction, of the two eaves 82d of the second eccentric portion bearing 82. The axial interval D3 between the restriction member 10M and the one eave 82D1 is smaller than the axial interval D4 between the two eaves 82D.

As shown in fig. 4 and 5, the outer diameter of the regulating member 10M is smaller than the inner diameter of the other eaves 82d2, and the other eaves 82d2 is an eaves located on the second journal 52 side together with the regulating member 10M, of the two eaves 82d of the second eccentric portion bearing 82. Therefore, a gap S1 is formed between the outer peripheral edge 10Ma of the restriction member 10M and the inner edge 82f of the other eave portion 82d2 as viewed in the axial direction. The gap S1 is formed in an annular shape as viewed in the axial direction. The outer peripheral edge 10Ma of the restriction member 10M and the inner edge 82f of the other eave portion 82d2 may be offset from each other in the axial direction, for example, but may be opposed to each other in the radial direction in the present embodiment.

As shown in fig. 4, the restricting member 10M of the present embodiment includes: a ring-shaped main body portion 10Mc through which the second collar portion 52 passes; and a contact convex portion 10Md that protrudes from the outer peripheral portion of the main body portion 10Mc in the axial direction toward the second eccentric portion bearing 82 and contacts the rolling element 82 a. In the present embodiment, the main body portion 10Mc and the contact convex portion 10Md are integrally formed.

The main body portion 10Mc is axially sandwiched between the second eccentric portion 54B and the crankshaft bearing 7M.

The outer peripheral portion of the main body portion 10Mc is a portion of the main body portion 10Mc that protrudes outward in the radial direction of the second eccentric portion 54B.

The contact convex portion 10Md of the present embodiment is formed in the entire circumferential direction of the main body portion 10 Mc. Thereby, the contact convex portion 10Md contacts the plurality of rolling elements 82a arranged in the circumferential direction of the second eccentric portion bearing 82. The contact convex portion 10Md may be arranged in plural in the circumferential direction of the main body portion 10Mc, for example.

The contact convex portion 10Md is disposed so as to radially face the outer peripheral surface of the second eccentric portion 54B. Therefore, the inner diameter of the contact convex portion 10Md may be larger than the diameter of at least the second eccentric portion 54B. More preferably, the difference between the inner diameter dimension of the contact convex portion 10Md and the diameter dimension of the second eccentric portion 54B is small.

Preferably, the hardness of the restricting member (particularly, the contact convex portion) that contacts the rolling elements of the second eccentric portion bearing is equal to or greater than the hardness of the rolling elements of the second eccentric portion bearing (for example, equal to or greater than 58 HRC). Further, it is preferable that the arithmetic mean roughness Ra of the surface of the restricting member (particularly, the contact convex portion) which is in contact with the rolling elements of the second eccentric portion bearing is, for example, 0.8 μm or less. In order to increase the hardness of the regulating member or to reduce the surface roughness of the regulating member, the regulating member (particularly, the contact convex portion) may be subjected to heat treatment, polishing treatment, or the like. By increasing the hardness of the restricting member or decreasing the surface roughness of the restricting member, it is possible to suppress wear of the restricting member (particularly, the contact convex portion) that is in contact with the rolling elements.

Although not shown, the restricting member 10M is disposed near the first eccentric portion 54A to which the first eccentric portion bearing 81 is attached after the first journal portion 51 (see fig. 1) of the crankshaft 5 is inserted. That is, the restricting member 10M is disposed on both sides of the first eccentric portion 54A and the second eccentric portion 54B so as to sandwich the first eccentric portion 54A and the second eccentric portion 54B in the axial direction.

The structure of the regulating member 10M disposed beside the first eccentric portion 54A may be the same as the structure of the regulating member 10M disposed beside the second eccentric portion 54B.

The bearing mechanism 100M and the speed reducer 1M according to the second embodiment have the same effects as those of the first embodiment. That is, the restricting member 10M that restricts the movement of the eccentric portion bearing 8 in the axial direction is in contact with the rolling elements 82a of the eccentric portion bearing 8. Therefore, when the eccentric portion bearing 8 is pressed against the regulating member 10M in the axial direction, at least the regulating member 10M contacts the rolling elements 82 a. Therefore, as compared with the case where the regulation member 10M is in contact with only the retainer 82b of the eccentric portion bearing 8, the load acting on the retainer 82b as the eccentric portion bearing 8 is pressed against the regulation member 10M can be reduced.

Therefore, the concentration of the load on the retainer 82b of the eccentric portion bearing 8 can be alleviated, and the retainer 82b can be protected. Further, since the eccentric portion bearing 8 can be protected, the reliability of the bearing mechanism 100M and the reduction gear 1M can be improved.

The above-described effects are particularly effective when the eccentric portion bearing 8 is a needle roller bearing that is easily movable in the axial direction thereof with respect to the crankshaft 5 (the eccentric portion 54).

Further, a gap S1 is formed between the outer peripheral edge 10Ma of the restricting member 10M and the inner edge 82f of the other eave portion 82d2 of the eccentric portion bearing 8 as viewed in the axial direction. Therefore, the lubricant (e.g., lubricant oil) easily reaches between the rolling elements 82a and the restricting member 10M that are in contact with each other, and the sliding surfaces of the rolling elements 82a (the surfaces of the rolling elements 82a that are in contact with the outer periphery of the crankshaft 5 and the inner periphery of the wobble gear) via the gap S1 between the restricting member 10M and the other lip 82d 2. This can suppress wear of the rolling elements 82a and the restricting member 10M that are in contact with each other. Therefore, the life of the bearing mechanism 100M can be prolonged.

Further, the interval D3 between the regulating member 10M (particularly, the contact convex portion 10Md) and the one eave portion 82D1 of the eccentric portion bearing 8 is smaller than the interval D4 in the axial direction between the eave portions 82D of the eccentric portion bearing 8. Therefore, the movement length of the rolling elements 82a in the axial direction can be suppressed to be smaller by the restricting member 10M. This can suppress the inclination of the rolling elements 82a with respect to the axial direction to a small degree. Therefore, the sliding resistance of the rolling elements 82a against the crankshaft 5 (the eccentric portion 54) can be reduced, and the skew force (the knob force) acting on the crankshaft 5 can be reduced.

The restricting member 10M (particularly, the main body portion 10Mc) is axially sandwiched and fixed between the eccentric portion 54 of the crankshaft 5 and the crankshaft bearing 7M disposed on the outer periphery of the journal portion 52. Therefore, the movement of the restriction member 10M in the axial direction with respect to the crankshaft 5 can be suppressed or prevented. This enables the movement of the eccentric portion bearing 8 in the axial direction relative to the crankshaft 5 to be effectively restricted by the restricting member 10M.

The regulating member 10M according to the second embodiment may be formed by separating the main body portion 10Mc and the contact convex portion 10Md, for example, and then fixed together by any means such as welding or a countersunk screw.

In this case, the hardness and the surface roughness of the contact convex portion 10Md contacting at least the rolling elements of the eccentric portion bearing 8 may be matched to those of the rolling elements of the eccentric portion bearing 8. That is, the hardness and surface roughness of the main body portion 10Mc may be different from those of the contact convex portion 10Md, for example.

The restricting member 10M according to the second embodiment can be fixed to the crankshaft 5 by any means such as screw fixation.

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

The number of the oscillating gears in the reduction gear of the present invention may be, for example, one, or three or more. The number of eccentric portions in the crankshaft may correspond to the number of oscillating gears.

The bearing mechanism of the present invention is not limited to the application to a reduction gear, and can be applied to any machine or device.

Claims

1. A bearing mechanism is provided with:

a roller bearing having a plurality of cylindrical rolling elements and a cage for holding the plurality of rolling elements; and

a restricting member that contacts the rolling elements of the roller bearing, thereby restricting movement of the roller bearing in an axial direction.

2. The bearing mechanism of claim 1,

the bearing mechanism includes a base member having an inner peripheral surface,

the plurality of rolling elements are disposed on the inner circumferential surface.

3. The bearing mechanism according to claim 2,

the rolling elements are formed in a cylindrical shape extending in an axial direction of the inner peripheral surface and arranged in a circumferential direction of the inner peripheral surface,

the restricting member is attached to a portion of the inner peripheral surface located axially beside the roller bearing, the restricting member being in contact with the rolling elements in the axial direction.

4. The bearing mechanism of claim 3,

the holder has: an annular portion disposed along the inner peripheral surface; and eaves protruding from both axial ends of the ring-shaped portion in a radial direction and located on both sides of the rolling elements in the axial direction,

the restricting member has: a body portion attached to the inner peripheral surface; and a contact convex portion that protrudes from an opposing surface of the main body portion that opposes the roller bearing in the axial direction and contacts the rolling element,

the contact projection has a projection length in the axial direction that is greater than the thickness of the brim in the axial direction.

5. The bearing mechanism of claim 3,

the restricting member has a housing recess recessed from an end surface facing the roller bearing side in the axial direction to house the brim.

6. A bearing mechanism according to any one of claims 3 to 5,

a radial length of a first eaves of the eaves, which is axially disposed between the restricting member and the rolling elements, is smaller than a radial length of a second eaves of the eaves, which axially positions the rolling elements between the second eaves and the first eaves.

7. A bearing mechanism is provided with:

a base member having an inner peripheral surface;

a roller bearing having: a plurality of rolling elements that are formed in a cylindrical shape extending in an axial direction of the inner circumferential surface and are arranged in a circumferential direction of the inner circumferential surface; and a holder, which includes: an annular portion disposed along the inner peripheral surface; and eaves which protrude from both ends in the axial direction of the ring-shaped portion in the radial direction and are positioned on both sides of the rolling elements in the axial direction, and the cage holds the plurality of rolling elements, and a length in the radial direction of a first eaves in the eaves of the cage is smaller than a length in the radial direction of a second eaves in the eaves, the second eaves positioning the rolling elements between the second eaves and the first eaves in the axial direction; and

a restriction member having: a body attached to a portion of the inner circumferential surface located axially beside the roller bearing such that the first flange is located axially between the body and the rolling elements; and a contact protrusion protruding from an opposing surface of the body portion opposing the roller bearing in the axial direction and contacting the rolling element, wherein a protruding length of the contact protrusion in the axial direction is larger than a thickness of the brim in the axial direction, and the restricting member contacts the rolling element to restrict movement of the roller bearing in the axial direction.

8. A speed reducer is provided with:

a bearing mechanism as claimed in any one of claims 2 to 7;

a rotating shaft rotatably supported by the inner circumferential surface via the roller bearing;

an outer cylinder, the base member being disposed inside the outer cylinder so as to be rotatable relative to the outer cylinder; and

a swing gear disposed inside the outer cylinder and configured to swing and rotate with rotation of the rotating shaft,

the rotation shaft is a crankshaft that relatively rotates the outer cylinder and the base member at a speed slower than a rotation speed of the rotation shaft based on the swing rotation of the swing gear.

9. A bearing mechanism is provided with:

a roller bearing having a plurality of cylindrical rolling elements and a cage for holding the plurality of rolling elements;

a restricting member that contacts the rolling elements of the roller bearing, thereby restricting movement of the roller bearing in an axial direction; and

a rotating shaft having an outer peripheral surface,

the plurality of rolling elements are disposed on the outer peripheral surface.

10. The bearing mechanism of claim 9,

the rolling elements are formed in a cylindrical shape extending in an axial direction of the rotating shaft and arranged in a circumferential direction of the outer circumferential surface,

the restricting member is formed in a ring shape through which the rotary shaft passes, is attached to a portion of the outer peripheral surface that is located axially beside the roller bearing, and is in contact with the rolling elements in the axial direction.

11. The bearing mechanism of claim 10,

the holder has: an annular portion disposed along the outer peripheral surface; and eaves protruding from both axial ends of the ring-shaped portion in a radial direction and located on both sides of the rolling elements in the axial direction,

a gap is formed between an outer peripheral edge of the restricting member and an inner edge of the brim as viewed in the axial direction.

12. The bearing mechanism according to claim 10 or 11,

the restricting member is disposed in such a manner that the rolling bodies are located between the restricting member and one of the eaves in the axial direction,

an axial interval between the restricting member and the one eave is smaller than an axial interval between the eaves.

13. The bearing mechanism of claim 10,

the rotating shaft has: a large-diameter shaft portion having an outer peripheral surface to which the roller bearing is attached; and a small-diameter shaft portion located axially beside the large-diameter shaft portion and having a smaller diameter than the large-diameter shaft portion,

the bearing mechanism includes a small-diameter bearing disposed on an outer periphery of the small-diameter shaft portion,

the restriction member is axially sandwiched and fixed between the large-diameter shaft portion and the small-diameter bearing.

14. A bearing mechanism is provided with:

a rotating shaft having: a large-diameter shaft portion having an outer peripheral surface; and a small-diameter shaft portion located axially beside the large-diameter shaft portion, the small-diameter shaft portion having a smaller diameter than the large-diameter shaft portion;

a small-diameter bearing disposed on an outer periphery of the small-diameter shaft portion;

a roller bearing having: a plurality of rolling elements that are formed in a cylindrical shape extending in an axial direction of the rotating shaft and are arranged in a circumferential direction of the outer circumferential surface; and a holder, which includes: an annular portion disposed along the outer peripheral surface; and a flange portion that protrudes in a radial direction from both ends in an axial direction of the ring-shaped portion, and is positioned on both sides of the rolling elements in the axial direction, and the cage holds the plurality of rolling elements; and

a restriction member having: a body portion formed in an annular shape through which the small-diameter shaft portion of the rotary shaft passes, and fixed by being interposed between the large-diameter shaft portion and the small-diameter bearing in an axial direction; and a contact protrusion that protrudes in an axial direction from an outer peripheral portion of the main body portion that protrudes outward in the radial direction from the large-diameter shaft portion toward the roller bearing and contacts the rolling element, wherein the restricting member is disposed such that the rolling element is located between the restricting member and one of the eaves portions in the axial direction, a gap between the restricting member and the one of the eaves portions in the axial direction is smaller than a gap between the eaves portions in the axial direction, and a gap is formed between the restricting member and an inner edge of the other of the eaves portions in the axial direction, and the restricting member contacts the rolling element to restrict movement of the roller bearing in the axial direction.

15. A speed reducer is provided with:

a bearing mechanism according to any one of claims 9 to 14;

a carrier having an inner circumferential surface through which the rotary shaft passes, the carrier rotatably supporting the rotary shaft;

an outer cylinder, inside of which the carrier is disposed to be rotatable relative to the outer cylinder; and

a swing gear having an inner circumferential surface through which the rotating shaft passes, the rotating shaft being rotatably supported by the roller bearing, the swing gear being disposed inside the outer cylinder and being configured to swing and rotate in accordance with rotation of the rotating shaft,

the rotation shaft is a crankshaft that relatively rotates the outer cylinder and the carrier at a speed slower than a rotation speed of the rotation shaft based on the swing rotation of the swing gear.