Bearings and reducers

Abstract

The present invention provides a bearing and a reducer. The bearing comprises: an outer ring; an inner ring having an inner peripheral surface and an axial end surface; and a rolling element arranged between the outer ring and the inner ring, and the load action line does not pass through the inner peripheral surface.

Description

Technical Field

[0001] The invention relates to a bearing and a reducer. Background Art

[0002] For industrial robots, machine tools, etc., a speed reducer is used to reduce the rotation speed of a rotation drive source such as a motor (for example, see Patent Document 1). The speed reducer described in Patent Document 1 includes: an external gear; an internal gear that meshes with the external gear; a housing provided with the internal gear; a gear frame that rotates relative to the housing; a main bearing disposed between the housing and the gear frame; and an eccentric body shaft that is rotatably supported on the gear frame by means of a tapered roller bearing. In this speed reducer, the external gear is mounted on the eccentric body of the eccentric body shaft by means of a needle bearing.

[0003] In addition, since the main bearing uses a tapered roller bearing, the allowable torque and the rigidity of the reducer can be improved compared to the structure using an angular contact ball bearing for the main bearing. On the other hand, since the load applied to the reducer increases, the deformation of the components of the reducer may increase, and the components of the reducer need to be formed in a manner with an appropriate thickness. In particular, since the portion of the main bearing where the inner ring is mounted is easily subjected to the load of the main bearing, it needs to be formed in a manner with a thickness that can suppress deformation.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2016-109264 Summary of the invention

[0005] Problem that the invention aims to solve

[0006] However, when the thickness of the components of the reducer must be large, the increase in design constraints and the enlargement of the reducer become problems. Therefore, there is room for improvement in suppressing the increase in the thickness of the components constituting the rotating equipment such as the reducer on which the bearing is installed.

[0007] Therefore, the present invention provides a bearing capable of reducing the thickness of a component of a rotating device and a speed reducer including the bearing.

[0008] Solutions for solving problems

[0009] A bearing according to one embodiment of the present invention includes an outer ring, an inner ring having an inner peripheral surface and an axial end surface, and rolling elements arranged between the outer ring and the inner ring, with a load action line not passing through the inner peripheral surface.

[0010] According to the bearing according to one aspect of the present invention, it is possible to prevent the load action line from passing through the wall portion of the member having the outer peripheral surface that holds the inner peripheral surface of the inner ring of the bearing so as to cross in the radial direction.

[0011] Here, the "wall portion" refers to a portion that does not include a space such as a "hole" or a "recessed portion".

[0012] This can prevent the wall portion of the member supporting the inner ring from deforming so as to bend radially inward, thereby reducing the load applied to the member supporting the inner ring. Therefore, the thickness of the component of the device to which the bearing is mounted can be reduced.

[0013] A bearing according to one technical solution of the present invention includes: an outer ring having a predetermined axis as its center; an inner ring having an end face in the direction of the axis; and a rolling element arranged between the outer ring and the inner ring, and a load action line passing through the end face.

[0014] According to the bearing according to one aspect of the present invention, it is possible to prevent the load action line from passing through the wall portion of the member having the outer peripheral surface that holds the inner peripheral surface of the inner ring of the bearing so as to cross in the radial direction.

[0015] This can prevent the wall portion of the member supporting the inner ring from deforming so as to bend radially inward, thereby reducing the load applied to the member supporting the inner ring. Therefore, the thickness of the component of the device to which the bearing is mounted can be reduced.

[0016] A technical solution of the present invention involves a reducer comprising: an outer member having an outer ring; an inner member having an inner ring and an axial hole that supports the shaft member so as to be rotatable; and a bearing arranged between the outer ring and the inner ring and having a load action line that does not pass through the inner circumferential surface of the axial hole.

[0017] According to the reducer involved in one technical solution of the present invention, it is possible to avoid the load action line passing through the inner peripheral surface of the shaft hole. As a result, it is possible to suppress the deformation of the portion formed between the outer peripheral surface of the inner member and the inner peripheral surface of the shaft hole with a smaller thickness in a manner of bending inward in the radial direction, and the load applied to the portion of the inner member where the inner ring is installed can be reduced. Therefore, the thickness of the portion of the inner member where the inner ring is installed can be reduced, and the reducer can be miniaturized.

[0018] For the reducer of the above technical solution, the contact angle of the bearing may be greater than 40° and less than 50°.

[0019] For the reducer of the above technical solution, the distance from the axial end face of the inner ring to the intersection of the surface of the inner ring and the load action line in the axial direction may be A, and the overall size of the inner ring and the outer ring in the axial direction may be B, satisfying the relationship 0≤A / B≤0.2.

[0020] In the reducer of the above technical solution, the distance in the axial direction from the axial end face of the inner ring to the intersection of the surface of the inner ring and the load action line may be A, and the dimension of the inner ring in the axial direction may be B1, satisfying the relationship 0≤A / B1≤0.3.

[0021] A reducer according to a technical solution of the present invention comprises: a bearing, the bearing comprising: an outer ring formed in an annular shape and having an outer rolling surface facing inward in the radial direction; an inner ring coaxially arranged with the outer ring and having an inner rolling surface facing outward in the radial direction; and a plurality of rollers rolling on the inner rolling surface and the outer rolling surface; an outer member on which the outer ring is mounted; an inner member having a bearing mounting portion on which the inner ring is mounted and the bearing mounting portion having an axial hole; an axial member arranged in the axial hole and rotatably supported by the inner member; and a needle roller bearing interposed between the bearing mounting portion and the axial member and having a plurality of rollers rolling on the inner rolling surface and the outer rolling surface. A plurality of rolling elements roll on the inner circumferential surface of the shaft hole, a load action line of the bearing passes through a position of the bearing mounting portion that is closer to the outside of the inner circumferential surface of the shaft hole in the axial direction of the bearing, the contact angle of the bearing is greater than 40° and less than 50°, a distance in the axial direction from the end of the inner ring on the outside in the axial direction to the intersection of the surface of the inner ring with the load action line is set to A, a dimension of the inner ring and the outer ring as a whole in the axial direction is set to B, and a dimension of the inner ring in the axial direction is set to B1, at this time, a relationship of 0≤A / B≤0.2 and a relationship of 0≤A / B1≤0.3 are satisfied.

[0022] According to the speed reducer according to one aspect of the present invention, the thickness of the bearing mounting portion can be reduced, and the speed reducer can be miniaturized.

[0023] Effects of the Invention

[0024] According to the technical aspects of the present invention, it is possible to provide a bearing capable of reducing the thickness of a component of a rotating device and a speed reducer including the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a half cross-sectional view of the speed reducer involved in embodiment.

[0026] Figure 2 Yes Figure 1 The figure is a partial enlarged view of the cross section of the reducer shown.

[0027] Figure 3 Yes Figure 2 The figure is a partial enlarged view of the cross section of the reducer shown.

[0028] Figure 4 Yes Figure 1 The figure is a partial enlarged view of the cross section of the reducer shown.

[0029] Figure 5 This is a graph showing the relationship between the contact angle, life, and rigidity of the first main bearing of the speed reducer according to the embodiment.

[0030] Description of Reference Numerals

[0031] 1. Speed ​​reducer; 2. Outer cylinder (outer member); 3. Gear rack (inner member); 4. Crankshaft (shaft member); 6A. 1st main bearing (bearing); 6B. 2nd main bearing (bearing); 7A. 1st crankshaft bearing (needle bearing); 7B. 2nd crankshaft bearing (needle bearing); 32. Main bearing mounting portion (bearing mounting portion); 41. 1st shaft mounting hole (shaft hole); 51. Main bearing mounting portion (bearing mounting portion); 54. 2nd shaft mounting hole (shaft hole); 61A, 61B, outer ring; 61c, outer rolling surface; 62A, 62B, inner ring; 62a, inner circumferential surface; 62b, end surface (axial end surface); 62d, inner rolling surface; 63A, 63B, roller (rolling element); 81, roller (rolling element); AL1, AL2, load action line; O, axis line. DETAILED DESCRIPTION

[0032] Hereinafter, a reducer 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in the following description, the same reference numerals are used for structures having the same or similar functions. Moreover, there are cases where repeated descriptions of these structures are omitted. The reducer 1 according to the present embodiment is, for example, an eccentric swing type gear transmission device applied to a joint portion of a robot arm, etc.

[0033] Figure 1 It is a half cross-sectional view of the speed reducer involved in embodiment.

[0034] like Figure 1As shown, the speed reducer 1 includes: an outer cylinder 2 (outer member) as a housing; a gear carrier 3 (inner member) rotatably supported by the outer cylinder 2; a plurality of crankshafts 4 (shaft members) rotatably supported by the gear carrier 3; a first swing gear 5A and a second swing gear 5B rotatably mounted on the plurality of crankshafts 4; a first main bearing 6A and a second main bearing 6B interposed between the outer cylinder 2 and the gear carrier 3; a first crankshaft bearing 7A and a second crankshaft bearing 7B interposed between the gear carrier 3 and the crankshaft 4; a first eccentric bearing 8A interposed between the crankshaft 4 and the first swing gear 5A; and a second eccentric bearing 8B interposed between the crankshaft 4 and the second swing gear 5B. The speed reducer 1 is an eccentric swing type gear transmission device that rotates the outer cylinder 2 and the gear carrier 3 relative to each other around the axis O so that the input shaft (not shown) rotates relative to the outer cylinder 2 and obtains an output rotation reduced by the input rotation of the input shaft. In the following description, the direction along the axis O is referred to as the axial direction (axial direction), the direction perpendicular to the axis O and extending radially from the axis O is referred to as the radial direction, and the direction rotating around the axis O is referred to as the circumferential direction. In addition, the "axial inner side" used in the following description refers to the center side of the outer cylinder 2, and the "axial outer side" refers to the side opposite to the center of the outer cylinder 2.

[0035] The outer cylinder 2 is formed into a cylindrical shape centered on the axis O. The inner peripheral surface of the outer cylinder 2 includes an internal tooth portion 21 formed with a plurality of pin grooves 21a, a first outer ring retaining portion 22 retaining an outer ring 61A of the first main bearing 6A, a second outer ring retaining portion 23 retaining an outer ring 61B of the second main bearing 6B, and a sealing portion 24 to which the oil seal 11 is mounted.

[0036] The internal tooth portion 21 is formed in the middle of the inner peripheral surface of the outer tube 2 in the axial direction. In addition, the "middle" used in this embodiment refers not only to the middle between the two ends of the object, but also includes the inner range between the two ends of the object. A plurality of pin grooves 21a extend in the axial direction respectively. A plurality of pin grooves 21a are arranged at equal intervals in the circumferential direction. In each pin groove 21a, a cylindrical internal tooth pin 25 is held rotatably.

[0037] The first outer ring holding portion 22 and the second outer ring holding portion 23 are located on opposite sides of the inner tooth portion 21. The first outer ring holding portion 22 and the second outer ring holding portion 23 are adjacent to the inner tooth portion 21 in the axial direction. The first outer ring holding portion 22 is located on the first side in the axial direction relative to the inner tooth portion 21. The first outer ring holding portion 22 extends in the axial direction with a certain inner diameter with the axis O as the center. The first outer ring holding portion 22 is connected to the inner tooth portion 21 via a step surface 26. The step surface 26 faces the outer side in the axial direction and extends in the circumferential direction and radial direction. The second outer ring holding portion 23 is located on the second side in the axial direction relative to the inner tooth portion 21. The second outer ring holding portion 23 extends in the axial direction with a certain inner diameter with the axis O as the center. The second outer ring holding portion 23 is connected to the inner tooth portion 21 via a step surface 27. The step surface 27 faces the outer side in the axial direction and extends in the circumferential direction and radial direction.

[0038] The sealing portion 24 is located on the side opposite to the inner tooth portion 21 across the first outer ring retaining portion 22. The sealing portion 24 is adjacent to the first outer ring retaining portion 22 in the axial direction. The sealing portion 24 extends with a certain inner diameter with the axis O as the center. The inner diameter of the sealing portion 24 is larger than the inner diameter of the first outer ring retaining portion 22. The sealing portion 24 is connected to the first outer ring retaining portion 22 via a step surface 28. The step surface 28 faces the outer side in the axial direction and extends in the circumferential direction and radial direction. The outer periphery of the oil seal 11 contacts the sealing portion 24.

[0039] The gear frame 3 functions as an output shaft on which a driven part that receives the output rotation of the reducer 1 is installed. The gear frame 3 is formed as a whole in a cylindrical shape with the axis O as the center. The gear frame 3 is arranged on the inner circumferential side of the outer cylinder 2. The gear frame 3 protrudes on both sides in the axial direction more than the outer cylinder 2. The gear frame 3 is formed to be able to be divided into a first gear frame assembly 30 and a second gear frame assembly 50 in the axial direction. The first gear frame assembly 30 is arranged on the first side in the axial direction relative to the second gear frame assembly 50. The surface of the first gear frame assembly 30 facing the side opposite to the second gear frame assembly 50 (the first side in the axial direction) is set as a mounting surface 30a for mounting the driven part. The first gear frame assembly 30 and the second gear frame assembly 50 are fastened to each other and integrated.

[0040] The first gear frame assembly 30 includes a base 31 and a plurality of support portions not shown. The base 31 is axially arranged on the same side as the first outer ring retaining portion 22 relative to the internal tooth portion 21 of the outer cylinder 2. The base 31 is formed in a disk shape centered on the axis O. The base 31 is rotatably supported on the outer cylinder 2 by means of the first main bearing 6A. The base 31 has a first main bearing mounting portion 32 for mounting the first main bearing 6A. The first main bearing mounting portion 32 is formed at the end of the base 31 on the axial side of the second gear frame assembly 50.

[0041] The outer peripheral surface of the base 31 includes a first inner ring holding portion 33 for holding the inner ring 62A of the first main bearing 6A and a sealing portion 34 for mounting the oil seal 11. The first inner ring holding portion 33 is the outer peripheral surface of the first main bearing mounting portion 32. At least a portion of the first inner ring holding portion 33 is opposite to the first outer ring holding portion 22 of the outer tube 2 in the radial direction. The first inner ring holding portion 33 extends in the axial direction with a certain outer diameter around the axis O as the center. The first inner ring holding portion 33 includes an axially inner end of the outer peripheral surface of the base 31. At least a portion of the sealing portion 34 is opposite to the sealing portion 24 of the outer tube 2 in the radial direction. The sealing portion 34 is adjacent to the first inner ring holding portion 33 in the axial direction. The sealing portion 34 is arranged on the outer side in the axial direction relative to the first inner ring holding portion 33. The sealing portion 34 extends in the axial direction with a certain outer diameter around the axis O as the center. The sealing portion 34 is connected to the first inner ring holding portion 33 via a stepped surface 35. The step surface 35 faces inward in the axial direction and extends in the circumferential direction and the radial direction. The inner peripheral portion of the oil seal 11 is in contact with the sealing portion 34 .

[0042] The base 31 has a first shaft mounting hole 41 (shaft hole) for inserting the crankshaft 4. The first shaft mounting holes 41 are provided in the same number as the plurality of crankshafts 4. The plurality of first shaft mounting holes 41 are arranged at equal intervals in the circumferential direction. The inner circumferential surface of the first shaft mounting hole 41 is formed into a circular shape when viewed from the axial direction. The first shaft mounting hole 41 opens on the inner side in the axial direction. At least a part of the first shaft mounting hole 41 is provided in the first main bearing mounting portion 32. The inner circumferential surface of the first shaft mounting hole 41 includes: a first shaft support portion 42, a bushing retaining portion 43, an expanded diameter portion 44 and a connecting portion 45. The first shaft support portion 42 and the expanded diameter portion 44 are located in the first main bearing mounting portion 32. The bushing retaining portion 43 and the connecting portion 45 are located on the outer side in the axial direction than the first main bearing mounting portion 32.

[0043] The first shaft support portion 42 is formed at the inner end portion of the first shaft mounting hole 41 in the axial direction. The first shaft support portion 42 extends in the axial direction with a certain inner diameter. The bushing retaining portion 43 is formed on the outer side in the axial direction relative to the first shaft support portion 42. The bushing retaining portion 43 is formed coaxially with the first shaft support portion 42. The bushing retaining portion 43 extends in the axial direction with a certain inner diameter. The inner diameter of the bushing retaining portion 43 is smaller than the inner diameter of the first shaft support portion 42. The enlarged diameter portion 44 is formed between the first shaft support portion 42 and the bushing retaining portion 43. The enlarged diameter portion 44 is connected to the first shaft support portion 42 and the bushing retaining portion 43. The enlarged diameter portion 44 is formed over the entire circumference in such a way as to enlarge the inner diameter so as to be larger than the inner diameter of the first shaft support portion 42 and the inner diameter of the bushing retaining portion 43. The connecting portion 45 is adjacent to the bushing retaining portion 43 in the axial direction. The communication portion 45 is formed on the side opposite to the first shaft support portion 42 across the bushing retaining portion 43. The communication portion 45 is open on the outside in the axial direction. The inner diameter of the communication portion 45 is smaller than the inner diameter of the bushing retaining portion 43. The sealing cap 12 is embedded inside the communication portion 45. A step surface 46 is formed between the bushing retaining portion 43 and the communication portion 45. The step surface 46 extends in a direction orthogonal to the axial direction. The step surface 46 faces the inside in the axial direction.

[0044] Although not shown, a plurality of support portions are provided one by one between a pair of first shaft mounting holes 41 in the circumferential direction. The plurality of support portions protrude in the axial direction from the base portion 31. The plurality of support portions are located inside the internal tooth portion 21 of the outer tube 2. The plurality of support portions are provided integrally with the base portion 31.

[0045] The second gear frame assembly 50 is arranged on the side opposite to the base 31 of the first gear frame assembly 30 across the internal tooth portion 21 of the outer cylinder 2 in the axial direction. That is, the second gear frame assembly 50 is arranged on the second side in the axial direction at a distance relative to the base 31. The second gear frame assembly 50 is fastened to the protruding ends of multiple support portions of the first gear frame assembly 30 and is integrated with the first gear frame assembly 30. The second gear frame assembly 50 is formed in a disc shape centered on the axis O. The second gear frame assembly 50 is rotatably supported on the outer cylinder 2 by means of a second main bearing 6B. The second gear frame assembly 50 has a second main bearing mounting portion 51 for mounting the second main bearing 6B. The second main bearing mounting portion 51 is formed at the inner end of the second gear frame assembly 50 in the axial direction.

[0046] The outer peripheral surface of the second gear frame assembly 50 has a second inner ring retaining portion 52 that retains the inner ring 62B of the second main bearing 6B. The second inner ring retaining portion 52 is the outer peripheral surface of the second main bearing mounting portion 51. At least a portion of the second inner ring retaining portion 52 is radially opposite to the second outer ring retaining portion 23 of the outer cylinder 2. The second inner ring retaining portion 52 extends axially with a certain outer diameter around the axis O as the center. The second inner ring retaining portion 52 includes an axially inner end portion of the outer peripheral surface of the second gear frame assembly 50. A step surface 53 extending in the circumferential direction and the radial direction is connected to the axially outer end portion of the second inner ring retaining portion 52.

[0047] The second gear frame assembly 50 has a second shaft mounting hole 54 (shaft hole) for inserting the crankshaft 4. The second shaft mounting holes 54 are set to be the same number as the plurality of crankshafts 4. Each second shaft mounting hole 54 is formed coaxially with the first shaft mounting hole 41 of the first gear frame assembly 30. The inner circumferential surface of the second shaft mounting hole 54 is formed in a circular shape when viewed from the axial direction. The second shaft mounting hole 54 is open on the inner side in the axial direction. At least a portion of the second shaft mounting hole 54 is provided in the second main bearing mounting portion 51. The inner circumferential surface of the second shaft mounting hole 54 has a second shaft support portion 55 and an internal thread portion 56. The entire second shaft support portion 55 and a portion of the internal thread portion 56 are located in the second main bearing mounting portion 51.

[0048] The second shaft support portion 55 is formed at the inner end portion of the second shaft mounting hole 54 in the axial direction. The second shaft support portion 55 extends in the axial direction with a certain inner diameter. The internal thread portion 56 is adjacent to the second shaft support portion 55 in the axial direction. The internal thread portion 56 is formed at the outer end portion of the second shaft mounting hole 54 in the axial direction. The inner diameter of the internal thread portion 56 is larger than the inner diameter of the second shaft support portion 55. A step surface 57 is formed between the second shaft support portion 55 and the internal thread portion 56. The step surface 57 extends in a direction orthogonal to the axial direction. The step surface 57 faces the outer side in the axial direction.

[0049] Figure 2 Yes Figure 1 The figure is a partial enlarged view of the cross section of the reducer shown.

[0050] like Figure 2 As shown, the first main bearing 6A is a tapered roller bearing and is disposed between the outer cylinder 2 and the base 31 of the first carrier assembly 30. The first main bearing 6A includes an outer ring 61A, an inner ring 62A, a plurality of rollers 63A, and a retainer 64A.

[0051] The outer ring 61A is formed into a circular ring centered on the axis O. The outer ring 61A is fitted into the first outer ring holding portion 22 of the outer tube 2. The outer ring 61A has an outer peripheral surface 61a extending at a certain outer diameter, an end surface 61b facing inward in the axial direction, and an outer rolling surface 61c inclined relative to the axis O. The end surface 61b contacts the step surface 26. The end surface 61b is opposite to the end of the inner tooth pin 25, and limits the displacement of the inner tooth pin 25 to the first side in the axial direction. The outer rolling surface 61c faces inward in the radial direction and outward in the axial direction.

[0052] The inner ring 62A is formed into a circular ring shape coaxial with the outer ring 61A. The inner ring 62A is fitted into the first inner ring retaining portion 33 of the base 31 of the first gear frame assembly 30. The inner ring 62A has: an inner peripheral surface 62a (inner peripheral surface of the hole) extending with a certain inner diameter, an end surface 62b (axial end surface) facing the outer side in the axial direction, a chamfered portion 62c formed between the inner peripheral surface 62a and the end surface 62b, and an inner rolling surface 62d inclined relative to the axis O. The end surface 62b contacts the step surface 35. The chamfered portion 62c is formed between the axially outer end of the inner peripheral surface 62a and the radially inner end of the end surface 62b. The inner rolling surface 62d is opposite to the outer rolling surface 61c of the outer ring 61A. The inner rolling surface 62d faces the outer side in the radial direction and faces the inner side in the axial direction.

[0053] The plurality of rollers 63A are disposed between the outer ring 61A and the inner ring 62A. The plurality of rollers 63A are arranged at equal intervals in the circumferential direction. The plurality of rollers 63A revolve around the axis O while rolling on the outer rolling surface 61c of the outer ring 61A and the inner rolling surface 62d of the inner ring 62A.

[0054] The retainer 64A is disposed between the outer ring 61A and the inner ring 62A. The retainer 64A retains the plurality of rollers 63A. The retainer 64A is formed in an annular shape coaxial with the outer ring 61A. The retainer 64A has a plurality of recessed portions that retain the plurality of rollers 63A one by one.

[0055] The contact angle θ of the first main bearing 6A is not less than 40° and not more than 50°. The contact angle θ is the inclination angle of the generatrix of the outer rolling surface 61c of the outer ring 61A relative to the axis O. In other words, the contact angle θ is the angle formed by the normal line at any point of the outer rolling surface 61c and the straight line that is orthogonal to the axis O and passes through the arbitrary point.

[0056] Here, the distance in the axial direction from the end face 62b of the inner ring 62A of the first main bearing 6A to the intersection point P of the surface of the inner ring 62A intersecting with the load action line AL1 (described later) is defined as A ( Figure 3 Reference). Moreover, the axial dimension of the inner ring 62A and the outer ring 61A as a whole is set to B. At this time, the first main bearing 6A is formed in a manner to satisfy the relationship shown in the following formula (1):

[0057] 0≤A / B≤0.2···(1).

[0058] In addition, the axial dimension of the inner ring 62A is set to B1. At this time, the first main bearing 6A is formed so as to satisfy the relationship shown in the following formula (2):

[0059] 0≤A / B1≤0.3···(2).

[0060] Figure 4 Yes Figure 1 The figure is a partial enlarged view of the cross section of the reducer shown.

[0061] like Figure 4 As shown, the second main bearing 6B is a tapered roller bearing. The second main bearing 6B is disposed between the outer cylinder 2 and the second carrier assembly 50. The second main bearing 6B includes an outer ring 61B, an inner ring 62B, a plurality of rollers 63B, and a retainer 64B.

[0062] The outer ring 61B is fitted into the second outer ring holding portion 23 of the outer tube 2. The outer ring 61B has, similarly to the outer ring 61A of the first main bearing 6A, an outer peripheral surface 61a extending at a certain outer diameter, an end surface 61b facing inward in the axial direction, and an outer rolling surface 61c inclined with respect to the axis O. The end surface 61b contacts the step surface 27. The end surface 61b is opposite to the end of the internal gear pin 25, and restricts the displacement of the internal gear pin 25 to the second side in the axial direction.

[0063] The inner ring 62B is fitted into the second inner ring retaining portion 52 of the second gear frame assembly 50. The inner ring has, similarly to the inner ring 62A of the first main bearing 6A, an inner peripheral surface 62a extending with a certain inner diameter, an end surface 62b facing outward in the axial direction, a chamfered portion 62c formed between the inner peripheral surface 62a and the end surface 62b, and an inner rolling surface 62d inclined relative to the axis O. The end surface 62b is opposite to the step surface 53. An annular spacer 13 is sandwiched between the end surface 62b and the step surface 53.

[0064] The plurality of rollers 63B are disposed between the outer ring 61B and the inner ring 62B. The plurality of rollers 63B are arranged at equal intervals in the circumferential direction. The plurality of rollers 63B revolve around the axis O while rolling on the outer rolling surface 61c of the outer ring 61B and the inner rolling surface 62d of the inner ring 62B.

[0065] The retainer 64B is disposed between the outer ring 61B and the inner ring 62B. The retainer 64B retains the plurality of rollers 63B. The retainer 64B is formed in an annular shape coaxial with the outer ring 61B. The retainer 64B has a plurality of recessed portions that retain the plurality of rollers 63B one by one.

[0066] The contact angle of the second main bearing 6B is not less than 40° and not more than 50°. The definition of the contact angle is the same as that of the first main bearing 6A. In addition, the second main bearing 6B is also formed in a manner that satisfies the relationship between the above formula (1) and the above formula (2) in the same manner as the first main bearing 6A.

[0067] like Figure 1 As shown, a plurality of crankshafts 4 are located on the inner circumferential side of the outer cylinder 2 and are arranged at equal intervals in the circumferential direction. Each crankshaft 4 is rotatably supported on the gear frame 3 by means of a pair of first crankshaft bearings 7A and second crankshaft bearings 7B. Specifically, each crankshaft 4 is rotatably supported on the first gear frame assembly 30 by means of the first crankshaft bearing 7A on the inner side of the first shaft mounting hole 41 of the first gear frame assembly 30. In addition, each crankshaft 4 is rotatably supported on the second gear frame assembly 50 by means of the second crankshaft bearing 7B on the inner side of the second shaft mounting hole 54 of the second gear frame assembly 50. Each crankshaft 4 has a first shaft neck portion 71 and a second shaft neck portion 72, a first eccentric portion 73 and a second eccentric portion 74, and a small diameter portion 75.

[0068] The first journal portion 71 is disposed inside the first shaft support portion 42 of the first carrier assembly 30. The second journal portion 72 is formed coaxially with the first journal portion 71.

[0069] The second journal portion 72 is disposed at a distance in the axial direction from the first journal portion 71. The second journal portion 72 is disposed inside the second shaft support portion 55 of the second carrier assembly 50.

[0070] The first eccentric portion 73 and the second eccentric portion 74 are arranged between the first neck portion 71 and the second neck portion 72. The first eccentric portion 73 is arranged on the first neck portion 71 side relative to the second eccentric portion 74. The first eccentric portion 73 and the second eccentric portion 74 are both formed in a cylindrical shape. The first eccentric portion 73 and the second eccentric portion 74 are eccentric with respect to the common axis of the first neck portion 71 and the second neck portion 72. The first eccentric portion 73 and the second eccentric portion 74 are eccentric with respect to the common axis of the first neck portion 71 and the second neck portion 72 by the same eccentricity. The first eccentric portion 73 and the second eccentric portion 74 are arranged in a manner that they have a phase difference of a predetermined angle (180° in the present embodiment) with respect to each other.

[0071] The small diameter portion 75 is arranged on the side opposite to the first journal portion 71 across the second journal portion 72. The small diameter portion 75 protrudes outward in the axial direction from the second journal portion 72. The small diameter portion 75 is formed coaxially with the second journal portion 72. The small diameter portion 75 protrudes outward in the axial direction than the gear carrier 3. For example, a gear meshing with the input shaft is mounted on the small diameter portion 75.

[0072] Each crankshaft 4 is retained on the gear frame 3 by a limiting member 14. The limiting member 14 includes a first limiting member 15 and a second limiting member 16. The first limiting member 15 is arranged on the inner side of the first shaft mounting hole 41 of the first gear frame assembly 30. The first limiting member 15 is formed in an annular shape coaxial with the first shaft mounting hole 41. The first limiting member 15 is fitted into the inner side of the bushing retaining portion 43 of the first shaft mounting hole 41. The first limiting member 15 is arranged between the step surface 46 and the first shaft neck portion 71. The first limiting member 15 contacts the step surface 46 from the inner side in the axial direction, and contacts or approaches the end surface of the first shaft neck portion 71 facing the outer side in the axial direction from the outer side in the axial direction.

[0073] The second limiting member 16 is arranged on the inner side of the second shaft mounting hole 54 of the second gear frame assembly 50. The second limiting member 16 is formed in a circular ring shape coaxial with the second shaft mounting hole 54. The second limiting member 16 is mounted on the internal thread portion 56. An external thread 16a that meshes with the internal thread portion 56 is formed on the outer peripheral surface of the second limiting member 16. The second limiting member 16 surrounds the small diameter portion 75 and is in contact with or close to the end face of the second shaft neck portion 72 facing the outer side in the axial direction.

[0074] The first crankshaft bearing 7A is a needle bearing and is disposed between the first carrier assembly 30 and the crankshaft 4. The first crankshaft bearing 7A includes a plurality of rollers 81 (rolling elements) and a cage 82 that holds the plurality of rollers 81.

[0075] A plurality of rollers 81 are arranged between the first shaft support portion 42 of the first gear frame assembly 30 and the outer peripheral surface of the first journal portion 71 of the crankshaft 4. The plurality of rollers 81 are arranged at equal angles around the first journal portion 71. The plurality of rollers 81 are formed into a cylindrical shape extending in the axial direction. Each roller 81 rolls on the first shaft support portion 42 and on the outer peripheral surface of the first journal portion 71. That is, the first main bearing mounting portion 32 has the first shaft support portion 42 as an inner peripheral surface, and the first main bearing mounting portion 32 functions as an outer ring of the first crankshaft bearing 7A. In addition, the first journal portion 71 functions as an inner ring of the first crankshaft bearing 7A.

[0076] The retainer 82 extends in an annular shape along the first shaft support portion 42. A recessed portion for retaining the plurality of rollers 81 is formed in the retainer 82. The retainer 82 protrudes to both sides in the axial direction from the plurality of rollers 81. The outer end of the retainer 82 in the axial direction can contact the first limiting member 15 from the inner side in the axial direction.

[0077] The second crankshaft bearing 7B is a needle bearing. The second crankshaft bearing 7B is disposed between the second carrier assembly 50 and the crankshaft 4. The second crankshaft bearing 7B is formed similarly to the first crankshaft bearing 7A. That is, the second crankshaft bearing 7B includes a plurality of rollers 81 and a retainer 82.

[0078] A plurality of rollers 81 are disposed between the second shaft support portion 55 of the second gear carrier assembly 50 and the outer peripheral surface of the second journal portion 72 of the crankshaft 4. Each roller 81 rolls on the second shaft support portion 55 and the outer peripheral surface of the second journal portion 72. That is, the second main bearing mounting portion 51 has the second shaft support portion 55 as an inner peripheral surface, and the second main bearing mounting portion 51 functions as an outer ring of the second crankshaft bearing 7B. In addition, the second journal portion 72 functions as an inner ring of the second crankshaft bearing 7B. The axially outer end of the retainer 82 can contact the second limiting member 16 from the axially inner side.

[0079] The first swing gear 5A and the second swing gear 5B are arranged between the base 31 of the first gear frame assembly 30 and the second gear frame assembly 50. The first swing gear 5A is arranged on the side of the base 31 of the first gear frame assembly 30 relative to the second swing gear 5B. The first swing gear 5A and the second swing gear 5B are formed into a disc shape having an outer diameter smaller than the inner diameter of the inner tooth portion 21 of the outer cylinder 2. The first swing gear 5A and the second swing gear 5B can swing and rotate relative to the gear frame 3, and can rotate around the axis O synchronously with the gear frame 3.

[0080] The first swing gear 5A has external teeth 91 and shaft through holes 92 of the same number as the plurality of crankshafts 4. The external teeth 91 are arranged on the outer peripheral surface of the first swing gear 5A over the entire circumference, and can mesh with the internal tooth pins 25 of the outer cylinder 2. The plurality of crankshafts 4 are inserted through the shaft through holes 92 one by one. The first eccentric portion 73 of the crankshaft 4 is arranged inside each shaft through hole 92. The shaft through hole 92 is mounted on the first eccentric portion 73 via the first eccentric bearing 8A.

[0081] The second swing gear 5B is formed similarly to the first swing gear 5A. The second eccentric portion 74 of the crankshaft 4 is arranged inside each shaft through hole 92. The shaft through hole 92 is attached to the second eccentric portion 74 via a second eccentric bearing 8B.

[0082] When the crankshafts 4 rotate and the first eccentric portion 73 rotates eccentrically, the first swing gear 5A rotates and swings around the axis O while meshing with a part of the internal tooth pins 25 in conjunction with the eccentric rotation of the first eccentric portion 73. When the second eccentric portion 74 rotates and the crankshafts 4 rotates eccentrically, the second swing gear 5B rotates and swings around the axis O while meshing with a part of the internal tooth pins 25 in conjunction with the eccentric rotation of the second eccentric portion 74. Therefore, the crankshafts 4 supported by the first swing gear 5A and the second swing gear 5B rotate around the axis O, and the gear carrier 3 supporting the crankshafts 4 rotates around the axis O.

[0083] In addition, although not shown, the first swing gear 5A and the second swing gear 5B are formed with the same number of escape holes as the plurality of support portions of the first gear frame assembly 30. The plurality of support portions penetrate through the escape holes one by one. Each escape hole is formed to have an inner diameter sufficiently large relative to the support portion so that each support portion does not hinder the swing rotation of the first swing gear 5A and the swing rotation of the second swing gear 5B.

[0084] The first eccentric bearing 8A is a needle bearing. The first eccentric bearing 8A is disposed between the first oscillation gear 5A and the crankshaft 4. The first eccentric bearing 8A includes a plurality of rollers 101 and a cage 102 that holds the plurality of rollers 101.

[0085] The plurality of rollers 101 are arranged between the inner peripheral surface of the shaft through hole 92 of the first swing gear 5A and the outer peripheral surface of the first eccentric portion 73 of the crankshaft 4. The plurality of rollers 101 are arranged at equal angles around the first eccentric portion 73. The plurality of rollers 101 are formed into a cylindrical shape extending in the axial direction. Each roller 101 rolls on the inner peripheral surface of the shaft through hole 92 of the first swing gear 5A and the outer peripheral surface of the first eccentric portion 73.

[0086] The retainer 102 extends in an annular shape along the inner peripheral surface of the shaft insertion hole 92. A recessed portion for retaining the plurality of rollers 101 one by one is formed in the retainer 102. The retainer 102 protrudes from the plurality of rollers 101 to both sides in the axial direction.

[0087] The second eccentric bearing 8B is a needle bearing. The second eccentric bearing 8B is disposed between the second swing gear 5B and the crankshaft 4. The second eccentric bearing 8B is formed similarly to the first eccentric bearing 8A. That is, the second eccentric bearing 8B includes a plurality of rollers 101 and a retainer 102.

[0088] A plurality of rollers 101 are arranged between the inner peripheral surface of the shaft through hole 92 of the second swing gear 5B and the outer peripheral surface of the second eccentric portion 74 of the crankshaft 4. The plurality of rollers 101 are arranged at equal angles around the second eccentric portion 74. The plurality of rollers 101 are formed into a cylindrical shape extending in the axial direction. Each roller 101 rolls on the inner peripheral surface of the shaft through hole 92 of the second swing gear 5B and the outer peripheral surface of the second eccentric portion 74.

[0089] The load action lines of each of the first main bearing 6A and the second main bearing 6B will be described. The load action lines are lines extending from the midpoint of the center axis (rolling axis) of each roller 63A, 63B so as to be orthogonal to the center axis.

[0090] like Figure 2As shown in FIG. 1 , the load action line AL1 of the first main bearing 6A passes through a position axially outside the inner peripheral surface 62a of the inner ring 62A of the first main bearing 6A. That is, the load action line AL1 does not pass through the inner peripheral surface 62a of the inner ring 62A of the first main bearing 6A. More specifically, the load action line AL1 passes through the chamfered portion 62c of the inner ring 62A.

[0091] The contact angle θ of the first main bearing 6A is greater than 40° and less than 50°, and is formed in a manner that the first main bearing 6A satisfies the relationship between at least one of the above-mentioned formula (1) and the above-mentioned formula (2). Thus, the load action line AL1 passes through a position axially outside the inner peripheral surface (the first shaft support portion 42 and the expanded diameter portion 44) of the first main bearing mounting portion 32 of the first gear frame assembly 30. In the present embodiment, the load action line AL1 passes through a position axially outside the first main bearing mounting portion 32. In addition, the load action line AL1 passes through a position axially outside the first shaft mounting hole 41 as a whole.

[0092] like Figure 4 As shown in FIG. 1 , the load action line AL2 of the second main bearing 6B passes through a position axially outward of the inner circumferential surface 62a of the inner ring 62B of the second main bearing 6B. More specifically, the load action line AL2 passes through the chamfered portion 62c of the inner ring 62B. The load action line AL2 passes through a position axially outward of the second inner ring retaining portion 52 on the inner circumferential surface of the second main bearing mounting portion 51.

[0093] As described above, in the present embodiment, the load action line AL1 of the first main bearing 6A does not pass through the inner peripheral surface 62a of the inner ring 62A. According to this structure, it is possible to avoid the load action line AL1 from passing through the wall portion of the member having the outer peripheral surface that holds the inner peripheral surface 62a of the inner ring 62A in a radially traversing manner, that is, the wall portion of the first main bearing mounting portion 32 of the gear carrier 3 that supports the first main bearing 6A. As a result, the wall portion of the first main bearing mounting portion 32 is suppressed from deforming in a radially inwardly flexing manner, and the load applied to the first main bearing mounting portion 32 can be reduced. Therefore, the thickness of the first main bearing mounting portion 32 can be reduced.

[0094] In addition, the speed reducer 1 of the present embodiment includes the above-mentioned first main bearing 6A, and the load action line AL1 does not pass through the inner peripheral surface of the first shaft mounting hole 41 of the first main bearing mounting portion 32. According to this structure, it is possible to avoid the load action line AL1 from passing through the outer peripheral surface (first inner ring holding portion 33) of the first main bearing mounting portion 32 and the inner peripheral surface of the first shaft mounting hole 41. As a result, the thin-walled portion formed between the outer peripheral surface of the first main bearing mounting portion 32 and the inner peripheral surface of the first shaft mounting hole 41 is suppressed from deforming in a manner of bending inward in the radial direction, and the load applied to the first main bearing mounting portion 32 can be reduced. Therefore, it is possible to achieve miniaturization of the speed reducer 1 by thinning the first main bearing mounting portion 32. In addition, it is possible to achieve an increase in the diameter of the first shaft mounting hole 41.

[0095] Furthermore, the first main bearing 6A may be formed so that the load action line AL1 passes through the end surface 62b of the inner ring 62A. According to this structure, since the load action line AL1 does not pass through the first main bearing mounting portion 32 of the gear carrier 3 supporting the first main bearing 6A, the load applied to the first main bearing mounting portion 32 can be reduced. Therefore, the deformation of the first main bearing mounting portion 32 is suppressed, and the thickness of the first main bearing mounting portion 32 can be reduced.

[0096] Here, the relationship between the contact angle of the first main bearing of the reducer of the embodiment and the life and rigidity of the reducer is described. The reducer of the embodiment is equivalent to the reducer 1 of the above-mentioned embodiment, and the contact angle of the first main bearing is changed by appropriately changing the shape of the outer rolling surface 61c of the outer ring 61A of the first main bearing 6A, the shape of the inner rolling surface 62d of the inner ring 62A, and the shape of the roller 63. In addition, for the first main bearing of the embodiment, the load action line passes through a position axially outside the inner circumferential surface of the inner ring when the contact angle is 40° or more. In addition, the load action line passes through the end surface of the inner ring when the contact angle is 45° or more.

[0097] Figure 5 Graph showing the relationship between the contact angle, life and rigidity of the first main bearing of the reducer of the embodiment. Figure 5 In the figure, the horizontal axis represents the contact angle of the first main bearing, the first vertical axis on the left side represents the life of the reducer, and the second vertical axis on the right side represents the rigidity of the reducer.

[0098] like Figure 5As shown, at least in the range of the contact angle of the first main bearing being 30° or more and 60° or less, the life of the reducer increases as the contact angle of the first main bearing increases. In addition, at least in the range of the contact angle of the first main bearing being 30° or more and 60° or less, the rigidity of the reducer increases as the contact angle of the first main bearing decreases. By setting the contact angle of the first main bearing 6A to be 40° or more and 50° or less, both the life and rigidity of the reducer 1 can be ensured in a well-balanced manner.

[0099] Furthermore, since the first main bearing 6A satisfies the relationship of the above formula (1), the load action line AL1 can pass through a position axially outside the first main bearing mounting portion 32. Therefore, the load applied to the first main bearing mounting portion 32 can be reduced.

[0100] Furthermore, since the first main bearing 6A satisfies the relationship of the above formula (2), the load action line AL1 can pass through a position axially outside the first main bearing mounting portion 32. Therefore, the load applied to the first main bearing mounting portion 32 can be reduced.

[0101] In addition, the speed reducer 1 includes a first crankshaft bearing 7A having rollers 81. The rollers 81 roll on the first shaft support portion 42 on the inner peripheral surface of the first shaft mounting hole 41. According to this structure, the first main bearing mounting portion 32 formed with the first shaft mounting hole 41 can function as the outer ring of the first crankshaft bearing 7A, so that the outer ring as an independent component can be omitted, and correspondingly, at least one of the reduction in diameter of the first main bearing mounting portion 32 and the increase in diameter of the first shaft mounting hole 41 can be achieved. The same is true for the second crankshaft bearing 7B.

[0102] In addition, the above mainly describes the effects related to the first main bearing 6A, but the same effects are also achieved for the second main bearing 6B. In addition, the first main bearing 6A is arranged at a position closer to the mounting surface 30a of the gear carrier 3 than the second main bearing 6B. Therefore, the torque applied to the first main bearing 6A is greater than the torque applied to the second main bearing 6B, and the above effects can be obtained to a greater extent for the first main bearing 6A.

[0103] In addition, the present invention is not limited to the above-mentioned embodiment described with reference to the drawings, and various modifications are conceivable within the technical scope of the present invention.

[0104] For example, in the above-mentioned embodiment, the first crankshaft bearing 7A is a needle roller bearing, and the main bearing mounting portion 32 functions as an outer ring, but the outer ring may be provided as an independent component. The same is true for the second crankshaft bearing 7B. In addition, the first crankshaft bearing and the second crankshaft bearing are not limited to the structure of needle roller bearings, and at least one of them may be a tapered roller bearing, for example.

[0105] In addition, in the above embodiment, the case where the gear carrier 3 is used as the output shaft is described as an example, but the present invention is not limited to this. That is, the gear carrier 3 may be fixedly provided and the housing 2 may be used as the output shaft.

[0106] Furthermore, components of the above-described embodiments may be appropriately replaced with known components without departing from the spirit of the present invention.

[0107] (Note 1)

[0108] A bearing, wherein

[0109] The bearing includes:

[0110] an outer ring formed in an annular shape centered on a predetermined axis and having an outer rolling surface facing a first side in an axial direction along the axis and facing inward in a radial direction;

[0111] an inner ring disposed coaxially with the outer ring, having an inner rolling surface facing the second side in the axial direction and facing the outer side in the radial direction, and an inner peripheral surface extending in the axial direction with a constant inner diameter; and

[0112] A plurality of rollers rolling on the inner rolling surface and the outer rolling surface,

[0113] The load action line passes through a position closer to the first side in the axial direction than the inner peripheral surface.

[0114] (Note 2)

[0115] A bearing, wherein

[0116] The bearing includes:

[0117] an outer ring formed in an annular shape centered on a predetermined axis and having an outer rolling surface facing a first side in an axial direction along the axis and facing inward in a radial direction;

[0118] an inner ring disposed coaxially with the outer ring, having an inner rolling surface facing the second side in the axial direction and facing the outer side in the radial direction, and an end surface facing the first side in the axial direction; and

[0119] A plurality of rollers rolling on the inner rolling surface and the outer rolling surface,

[0120] The load action line passes through the end surface of the inner ring.

Claims

1. A reducer, wherein: The reducer includes: A tapered roller bearing having an outer ring, an inner ring, and a plurality of rollers arranged between the outer ring and the inner ring; an outer member that engages with the outer ring and is mounted with the outer ring; and an inner member which is fitted with the inner ring and to which the inner ring is mounted, and has a bearing mounting portion to which the inner ring is mounted and a shaft hole for rotatably supporting the shaft member, At least a portion of the shaft hole is disposed on the bearing mounting portion, The tapered roller bearing has a load action line that does not pass through the inner peripheral surface of the axial hole.

2. The reducer according to claim 1, wherein: The contact angle of the tapered roller bearing is not less than 40° and not more than 50°.

3. The reducer according to claim 1, wherein: The distance in the axial direction from the axial end surface of the inner ring to the intersection point where the surface of the inner ring and the load action line intersect is A. The dimension of the inner ring and the outer ring as a whole in the axial direction is B, The following relations are satisfied: 0≤A / B≤0.

2.

4. The reducer according to claim 1, wherein: The distance in the axial direction from the axial end surface of the inner ring to the intersection point where the surface of the inner ring and the load action line intersect is A. The dimension of the inner ring in the axial direction is B1. The following relations are satisfied: 0≤A / B1≤0.

3.

5. A reducer, wherein: The reducer includes: A tapered roller bearing, the bearing comprising: an outer ring formed in an annular shape and having an outer rolling surface facing inward in a radial direction; an inner ring arranged coaxially with the outer ring and having an inner rolling surface facing outward in the radial direction; and a plurality of rollers rolling on the inner rolling surface and the outer rolling surface; an outer member on which the outer ring is mounted; An inner member having a bearing mounting portion on which the inner ring is mounted and an axial hole penetrating in the axial direction; a shaft member inserted into the shaft hole and rotatably supported by the inner member; and a needle roller bearing interposed between the bearing mounting portion and the shaft member and having a plurality of rolling elements rolling on the inner peripheral surface of the shaft hole, At least a portion of the shaft hole is disposed on the bearing mounting portion, The load action line of the tapered roller bearing passes through a position that is outside the entire inner peripheral surface of the shaft hole in the axial direction. The contact angle of the tapered roller bearing is greater than or equal to 40° and less than or equal to 50°. A is a distance in the axial direction from the outer end of the inner ring in the axial direction to an intersection point of the surface of the inner ring with the load action line. The dimension of the inner ring and the outer ring as a whole in the axial direction is set to B. The dimension of the inner ring in the axial direction is set to B1, and the following relationship is satisfied: 0≤A / B≤0.2, and 0≤A / B1≤0.3.

Images