Reducer, cage and bearing

Abstract

One of the purposes of the present invention is to provide a technology for a speed reducer capable of ensuring the lubricity of a bearing. A speed reducer (100) is provided with a bearing, wherein the bearing has a retaining frame (40) for retaining a plurality of rolling elements (25), wherein the retaining frame (40) has a column portion (43) for limiting the circumferential movement of the plurality of rolling elements (25) and an anti-falling portion (44) formed on the column portion (43) and used to prevent the rolling elements (25) from falling off, wherein the anti-falling portion (44) is arranged on the inner diameter side and arranged to be biased toward one side in the extension direction of the column portion (43).

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-049616 filed on March 24, 2021. The entire contents of the Japanese Patent Application are incorporated herein by reference. Technical Field

[0002] The invention relates to a reducer, a retaining frame and a bearing. Background Art

[0003] A reducer having a main bearing and a rolling element is known. Patent document 1 describes a gear transmission device in which a wheel carrier is supported on a housing via a bearing. The bearing has an inner ring provided on the wheel carrier, an outer ring provided on the housing, a plurality of rollers and a retainer. A groove for accommodating the end of the large diameter side of the retainer is provided on either the housing or the wheel carrier.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-137705

[0005] The present inventors have studied a speed reducer including a bearing, and as a result, have obtained the following findings.

[0006] The bearing has rolling elements and a cage surrounding the rolling elements. In order to ensure the reliability of the reducer, it is important to stably supply lubricating material to the rolling elements of the bearing to ensure lubricity. However, the reducer of Patent Document 1 does not take sufficient measures from the perspective of ensuring the lubricity of the bearing, and there is still room for improvement. Summary of the invention

[0007] The present invention has been made in view of the above situation, and one of its objects is to provide a technology for a speed reducer capable of ensuring lubricity of a bearing.

[0008] In order to solve the above-mentioned problem, a speed reducer of one embodiment of the present invention has a bearing, wherein the bearing has a retaining frame for retaining a plurality of rolling elements, wherein the retaining frame has a plurality of column portions for limiting the circumferential movement of the plurality of rolling elements and an anti-falling portion formed on the column portion to prevent the rolling elements from falling off. The anti-falling portion is arranged on the inner diameter side and is arranged to be biased toward one side in the extension direction of the column portion.

[0009] Another embodiment of the present invention is a retainer. The retainer is a retainer for a bearing that retains multiple rolling elements, and has multiple column portions that restrict the multiple rolling elements from moving in the circumferential direction and an anti-falling portion formed on the column portion to prevent the rolling elements from falling off. The anti-falling portion is arranged on the inner diameter side and is arranged to be biased to one side in the extension direction of the column portion.

[0010] Another embodiment of the present invention is a bearing. The bearing has a retainer that retains a plurality of rolling elements, wherein the retainer has a plurality of columnar portions that restrict the plurality of rolling elements from moving in the circumferential direction and an anti-falling portion formed on the columnar portion to prevent the rolling elements from falling off. The anti-falling portion is arranged on the inner diameter side and is arranged to be biased toward one side in the extension direction of the columnar portion.

[0011] In addition, any combination of the above-mentioned constituent elements or any form in which constituent elements or expressions of the present invention are replaced with each other in methods, systems, etc. may also be practiced as additional embodiments of the present invention.

[0012] According to the present invention, a technology of a speed reducer capable of ensuring lubricity of a bearing is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a side cross-sectional view showing the speed reducer according to the embodiment.

[0014] Figure 2 yes Figure 1 Cross-sectional view of the reducer taken along line AA.

[0015] Figure 3 It is a magnified representation Figure 1 Cross-sectional view of the main bearing.

[0016] Figure 4 Yes means Figure 1 A side view and a front view of an example of a retainer.

[0017] Figure 5 It is a magnified representation Figure 4 Figure 2. A diagram of the column portion of a cage.

[0018] Figure 6 It means from Figure 5 Figure 2 shows the retainer when viewed in the direction of arrow B.

[0019] Figure 7 It means from Figure 5 Figure 2 shows the retainer when viewed in the direction of arrow C.

[0020] Figure 8 yes Figure 5 A cross-sectional view taken along line DD.

[0021] In the figure: 100-reducer, 25-rolling element, 27-inner ring, 28-outer ring, 40-retaining frame, 41-large end, 43-column, 44-anti-falling portion, 45-fitting portion, 273-movement limiting portion, 282-recess, 283-retaining frame movement limiting portion, 433-step portion. DETAILED DESCRIPTION

[0022] Hereinafter, the preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments and modified examples, the same or equivalent components and parts are marked with the same symbols, and repeated descriptions are appropriately omitted. In addition, in order to facilitate understanding, the size of the components is appropriately enlarged or reduced in each drawing. In addition, in each drawing, a part of the components that are not important for the description of the embodiment is omitted.

[0023] Furthermore, terms including numbers such as 1 and 2 are used to describe various constituent elements, but such terms are only used to distinguish one constituent element from other constituent elements, and such terms are not used to limit the constituent elements.

[0024] [Implementation Method]

[0025] Hereinafter, the structure of the reduction gear 100 according to the embodiment of the present invention will be described with reference to the drawings. Figure 1 It is a side cross-sectional view schematically showing the reduction gear 100 according to the present embodiment. Figure 2 yes Figure 1 The use of the reducer 100 is not limited, but in this example, the reducer 100 can be used in the joints of a multi-joint robot, for example.

[0026] The overall structure of the speed reducer 100 is described below. The speed reducer 100 mainly includes: an eccentric body shaft 12; an external gear 14; an internal gear 16; wheel carriers 18 and 20; a housing 22; main bearings 24 and 26; an eccentric body bearing 30; an inner pin 32; and eccentric body shaft bearings 33 and 34. The main bearings 24 and 26 include an inner ring 27, an outer ring 28, a retainer 40, and a plurality of rolling elements 25. The main bearings 24 and 26 are an example of a bearing.

[0027] Hereinafter, the direction along the central axis La of the internal gear 16 is referred to as the "axial direction of the reducer" or simply the "axial direction", and the circumferential direction and radial direction of the circle centered on the central axis La are referred to as the "circumferential direction" and the "radial direction", respectively. Also, below, for ease of explanation, one side in the axial direction (the right side in the figure) is referred to as the input side, and the other side (the left side in the figure) is referred to as the opposite input side. Such directional marking does not limit the use posture of the reducer 100, and the reducer 100 can be used in any posture.

[0028] The wheel carriers 18 and 20 include a first wheel carrier 18 arranged on the opposite side of the input of the external gear 14 and a second wheel carrier 20 arranged on the input side of the external gear 14. The main bearings 24 and 26 include a first main bearing 24 arranged on the opposite side of the input of the external gear 14 and a second main bearing 26 arranged on the input side of the external gear 14. The eccentric body shaft bearings 33 and 34 include a first eccentric body shaft bearing 33 arranged on the opposite side of the input of the external gear 14 and a second eccentric body shaft bearing 34 arranged on the input side of the external gear 14.

[0029] The speed reducer 100 of the present embodiment is a center crank type in which the eccentric body shaft 12 is arranged coaxially with the center axis La of the internal gear 16. The speed reducer 100 has a hollow portion H penetrating in the axial direction at the center. The hollow portion H is provided in the eccentric body shaft 12.

[0030] The housing 22 constitutes the outer shell of the speed reducer 100. The wheel carriers 18 and 20 are arranged inside the housing 22 and rotate relative to the housing 22. The eccentric body shaft 12 has a hollow cylindrical shape having a hollow portion H at the center. For example, a motor shaft is connected to the end of the input side of the eccentric body shaft 12 by a fastener such as a bolt.

[0031] The eccentric body shaft 12 has a plurality of eccentric portions 128, thereby functioning as an eccentric body that causes the external gear 14 to swing. In this example, the eccentric body shaft 12 has two eccentric portions 128 that are 180° out of phase with each other. Both ends of the eccentric body shaft 12 are supported on the wheel frames 18 and 20 via eccentric body shaft bearings 33 and 34. In addition, the number of eccentric portions 128 is not limited to two, and may be one or more than three.

[0032] The structure of the eccentric body shaft bearings 33 and 34 is not limited. In this example, the first eccentric body shaft bearing 33 arranged on the opposite side of the input is a deep groove ball bearing whose rolling element is a ball (spherical body). The rolling element rolls between the inner ring and the outer ring. The second eccentric body shaft bearing 34 arranged on the input side is a roller bearing whose rolling element is a roller (cylindrical body). The second eccentric body shaft bearing 34 does not have an inner ring and an outer ring, and the rolling element rolls between the outer peripheral surface of the eccentric body shaft 12 and the inner peripheral surface of the second wheel frame 20.

[0033] In this embodiment, the eccentric bearing 30 has a cylindrical roller-shaped rolling element 302 and a retainer. A plurality of (for example, 38) rolling elements 302 are arranged around the eccentric portion 128 at predetermined intervals. The retainer holds the plurality of rolling elements 302 rotatably at a predetermined position. The eccentric bearing 30 does not have an inner ring and an outer ring, and the rolling element 302 rolls between the outer peripheral surface of the eccentric portion 128 and the inner peripheral surface of the center hole 14c of the external gear 14.

[0034] like Figure 2 As shown, the external gear 14 is rotatably supported by the corresponding eccentric portion 128 via the eccentric body bearing 30. The external gear 14 is formed with a center hole 14c and a plurality of inner pin holes 14h. The center hole 14c is a through hole provided at the center of the external gear 14. The plurality of inner pin holes 14h are through holes provided at positions deviated from the center of the external gear 14. Figure 2In the example of FIG. 1 , ten inner pin holes 14h are arranged at intervals of 36° in the circumferential direction. The inner pin 32 is inserted into the inner pin hole 14h. The teeth formed on the outer periphery of the external gear 14 rotate while meshing with the teeth of the internal gear 16, and the external gear 14 swings.

[0035] like Figure 2 As shown, the internal gear 16 meshes with the external gear 14. The internal gear 16 of this embodiment is composed of an internal gear body integrated with the housing 22 and an outer pin 16p (pin member) rotatably supported on the internal gear body. The outer pin 16p constitutes the internal teeth of the internal gear 16. The number of internal teeth of the internal gear 16 (the number of outer pins 16p) is slightly greater than the number of external teeth of the external gear 14 (in this example, only one more).

[0036] like Figure 1 As shown, the first carrier 18 and the second carrier 20 are rotatably supported by the housing 22 via the main bearing 24 and the main bearing 26. The first carrier 18 supports the eccentric shaft 12 via the first eccentric shaft bearing 33. The second carrier 20 supports the eccentric shaft 12 via the second eccentric shaft bearing 34.

[0037] The first carrier 18 and the second carrier 20 are connected to each other via the inner pin 32. The inner pin 32 penetrates the inner pin hole 14h of the external gear 14 in the axial direction at a position offset from the axial center of the external gear 14 in the radial direction.

[0038] One of the wheel carriers 18, 20 and the housing 22 functions as an output component that outputs rotational power to the driven device, and the other functions as a fixed component fixed to an external component for supporting the reducer 100. In this embodiment, the output components are the first wheel carrier 18 and the second wheel carrier 20, and the fixed component is the housing 22.

[0039] exist Figure 2 In the example of , ten inner pins 32 are arranged at intervals of 36° in the circumferential direction. Figure 1 Only one inner pin 32 is shown in FIG. The inner pin 32 is fixed to the first wheel frame 18 on the opposite side of the input, and is fixed to the second wheel frame 20 on the input side. The inner pin 32 connects the first wheel frame 18 and the second wheel frame 20. Figure 1 In the example, the inner pin 32 is formed integrally with the first wheel frame 18, and the input side is fixed to the second wheel frame 20 by bolts B1. A sleeve 32s is provided on the outer periphery of the inner pin 32. The inner pin 32 is inserted into the inner pin hole 14h with a gap between it and the inner pin hole 14h. The inner pin 32 abuts against a part of the inner pin hole 14h via the sleeve 32s. The inner pin 32 restricts the rotation of the outer gear 14 and only allows it to swing.

[0040] The main bearings 24 and 26 are arranged between the first wheel carrier 18 and the housing 22 and between the second wheel carrier 20 and the housing 22. The structure of the main bearings 24 and 26 is not limited, but in this example, the main bearings 24 and 26 are roller bearings whose rolling elements 25 are cylindrical rollers. The retaining frame 40 retains a plurality of rolling elements 25. The outer ring 28 of the main bearings 24 and 26 is supported by the housing 22. The inner ring of the first main bearing 24 is formed integrally with the wheel carrier 18. The inner ring of the second main bearing 26 is formed integrally with the wheel carrier 20.

[0041] The housing 22 is a hollow cylindrical component surrounding the wheel carriers 18 and 20. Figure 1 As shown, an oil seal 36 for sealing the lubricant from the first main bearing 24 is provided between the housing 22 and the first carrier 18 .

[0042] Hereinafter, the characteristic structure of this embodiment will be described.

[0043] The present inventors have studied a speed reducer including a main bearing and have obtained the following findings.

[0044] As a result of the study, it was found that improving the lubricity of rolling elements is effective in ensuring the bearing life of the main bearing of the speed reducer. The main bearing has a retaining frame that holds a plurality of rolling elements in a predetermined position. The retaining frame has a portion that surrounds the rolling elements in order to hold the rolling elements. The portion surrounding the rolling elements may become the main reason for narrowing the flow path of the lubricating material and causing a decrease in lubricity. In addition, in the speed reducer, from the perspective of improving assembly performance, in order to support the rolling elements and prevent them from falling when assembling the main bearing, it may be considered to provide a rolling element support portion on the retaining frame. However, such a rolling element support portion may narrow the flow path of the lubricating material and cause a decrease in lubricity.

[0045] Therefore, the inventors of the present invention proposed a retaining frame that can ensure assemblability and lubricity. The retaining frame has a column portion that limits the circumferential movement of multiple rolling elements and an anti-falling portion formed on the column portion and used to prevent the rolling elements from falling off, and the anti-falling portion is arranged on the inner diameter side and arranged to be biased to one side of the column portion. By having the anti-falling portion, the rolling elements can be prevented from falling off during assembly, and by configuring the anti-falling portion to be biased to one side, the flow path of the lubricating material is ensured, thereby suppressing the reduction in lubricity. By having this retaining frame, a reducer that can ensure the bearing life of the main bearing is provided. The following is a detailed description.

[0046] refer to Figure 1 and Figure 3 The main bearings 24 and 26 will be described. Here, the first main bearing 24 will be described, but this description is also applicable to the second main bearing 26 . Figure 3 It is a magnified representation Figure 14 is a cross-sectional view of the first main bearing 24. As described above, the first main bearing 24 includes the outer ring 28, the retainer 40, and the plurality of rolling elements 25. The first main bearing 24 is injected with a lubricant G. The direction along the central axis Lb of the rolling element 25 is referred to as the "axial direction of the rolling element", and the circumferential direction and radial direction of the circle centered on the central axis Lb are referred to as the "circumferential direction of the rolling element" and the "radial direction of the rolling element", respectively.

[0047] refer to Figure 1 , Figure 3 , Figure 4 and Figure 5 The retainer 40 will be described. Figure 4 (A) is a side view of the retainer 40. Figure 4 Center (B) is a front view of the retainer 40. In this figure, a part of the column part 43 is cut away. Figure 5 It is a diagram showing an enlarged view of the column portion 43 of the retainer 40 .

[0048] The retainer 40 mainly includes a large end portion 41, a small end portion 42, a plurality of column portions 43, a plurality of anti-drop portions 44, and a fitting portion 45. The retainer 40 is a hollow annular component having a substantially truncated cone-shaped outer contour as a whole. The outer diameter side of the retainer 40 is surrounded by the outer ring 28, and the inner ring 27 is accommodated on the inner diameter side of the retainer 40. The end face with a larger outer diameter at both ends of the column portion 43 of the retainer 40 in the extending direction is called a large end face (in the inner diameter side). Figure 3 The end face with the smaller outer diameter at both ends of the column portion 43 of the retainer 40 in the extending direction is called the small end face (in Figure 3 In other words, the side with a larger outer diameter of the circle drawn by the axes of the rolling elements can be called the large end face side, and the side with a smaller outer diameter of the circle drawn by the axes of the rolling elements can be called the small end face side. The retainer 40 has a large end 41 on the large end face side and a small end 42 on the small end face side. The large end 41 and the small end 42 are annular components that are substantially coaxial with the center axis La.

[0049] Also refer to Figure 6 to Figure 8 . Figure 6 is from Figure 5 The figure is viewed from the direction of arrow B. Figure 7 is from Figure 5 The figure is viewed from the direction of arrow C. Figure 8 is along Figure 5 These figures show the capsule box Pk of the retaining frame 40.

[0050] The plurality of columns 43 restrict the circumferential movement of the plurality of rolling elements 25. In this example, the plurality of columns 43 are radially arranged at predetermined intervals around the center axis La in the same number (for example, 61) as the plurality of rolling elements 25. On the surface passing through the center axis La, the column 43 extends in an extension direction inclined relative to the center axis La. The extension direction of the column 43 is a direction away from the center axis La as it approaches the large end portion 41. The outer diameter side of the column 43 is connected to the large end portion 41, and the inner diameter side of the column 43 is connected to the small end portion 42. As shown in FIG. Figure 6 As shown, two circumferentially adjacent columnar portions 43-A and 43-B, the large end portion 41 and the small end portion 42 form a pocket Pk having a substantially rectangular space. The rolling element 25 is accommodated in the pocket Pk.

[0051] The retainer 40 has an anti-dropout portion 44 formed on the column 43 to prevent the rolling element 25 from falling out of the capsule box Pk. The anti-dropout portion 44 has, for example, a claw shape. The shape of the anti-dropout portion 44 is not limited, but in this example, the anti-dropout portion 44 is arranged on the inner diameter side and is arranged to be biased towards either the large end portion 41 side or the small end portion 42 side of the column 43. At this time, by arranging the anti-dropout portion 44 on the inner diameter side, when the rolling element 25 is inserted into the capsule box Pk from the outer diameter side, the rolling element 25 is supported by the anti-dropout portion 44, and the rolling element can be prevented from falling toward the inner diameter side. In addition, the anti-dropout portion 44 is arranged to be biased towards one side of the column 43, which means that the length of the anti-dropout portion 44 located on one side in the extension direction relative to the center of the column 43 in the extension direction is greater than the length of the anti-dropout portion 44 located on the other side. Therefore, the anti-dropout portion 44 is configured to be biased to one side of the column 43, which does not include the situation that the overall area of ​​the anti-dropout portion 44 is biased in the axial direction. In addition, the anti-dropout portion 44 is configured to be biased to one side of the column 43, which also includes the situation that the anti-dropout portion 44 exists only on one side and the length of the anti-dropout portion 44 on the other side is zero.

[0052] The anti-dropout portion 44 may be arranged close to the small end portion 42 of the column portion 43, but in this example, the anti-dropout portion 44 is arranged close to the large end portion 41 of the column portion 43. In this case, the rolling element 25 is supported by the large end portion 41, and the gap is increased by the small end portion 42, so that the flow of the lubricant G can be smoothed.

[0053] The shape of the anti-falling portion 44 is not limited as long as it can prevent the rolling element 25 from falling off. Figure 6 In the example, the anti-falling portion 44 has a curved surface such as an arc shape at the portion in contact with the curved surface of the rolling element 25. In this case, the protrusion near the center of the anti-falling portion 44 can be increased to prevent the rolling element 25 from falling off, and the protrusion of the peripheral portion can be reduced to form a gap to ensure the flow path of the lubricating material G in this portion.

[0054] And, in Figure 6 In the example, regarding the thickness in the circumferential direction, the maximum thickness T1 of the portion other than the anti-falling portion 44 on the side of the column 43 where the anti-falling portion 44 exists is greater than the maximum thickness T2 on the side where the anti-falling portion 44 does not exist. In this case, the rigidity of the side supporting the rolling element 25 can be increased to suppress deformation. In this example, the maximum thickness T1 is the maximum thickness of the portion other than the anti-falling portion 44 on the side of the large end portion 41 of the column 43 where the anti-falling portion 44 exists, and the maximum thickness T2 is the maximum thickness on the side of the small end portion 42 of the column 43 where the anti-falling portion 44 does not exist.

[0055] And, in Figure 5 In the example, regarding the thickness in the direction orthogonal to the extension direction and the circumferential direction of the column 43 and passing through the central axis Lb, the thickness H1 of the column 43 on the side where the anti-falling portion 44 exists is greater than the thickness H2 of the column 43 on the side where the anti-falling portion 44 does not exist. In this case, the rigidity of the side supporting the rolling element 25 can be increased to suppress deformation. In this example, the thickness H1 is the maximum thickness on the side of the large end 41 of the column 43 where the anti-falling portion 44 exists, and the thickness H2 is the maximum thickness on the side of the small end 42 of the column 43 where the anti-falling portion 44 does not exist.

[0056] Next, the fitting portion 45 will be described. Figure 3 In the example of FIG. 1 , the retainer 40 has a fitting portion 45 that fits into the recess 282 of the outer ring 28 of the first main bearing 24. At this time, the rolling element 25 is provided in the retainer 40 with the large end 41 facing downward, and the outer ring 28 is placed so that the fitting portion 45 fits into the recess 282, thereby making them an integrated unit.

[0057] For example, the recessed portion 282 may be a circumferential recessed portion recessed in the inner circumferential surface of the outer ring 28. For example, the fitting portion 45 may be a convex portion protruding radially from the large end portion 41. The fitting portion 45 may be provided continuously in the circumferential direction, but in the present embodiment, the fitting portion 45 is provided intermittently at predetermined intervals in the circumferential direction. In particular, the fitting portion 45 is provided between the first column portion 43-A and the second column portion 43-B arranged in the circumferential direction among the plurality of column portions 43 of the large end portion 41. In this case, the fitting portion 45 can be easily embedded in the recessed portion 282.

[0058] In this embodiment, the fitting portion 45 is fitted into the recessed portion 282 of the outer ring 28 by elastic deformation. At this time, the retainer 40 is temporarily attached to the outer ring 28 by elastic deformation, so they can be easily used as an integrated unit. For example, in this unit, the shapes of the fitting portion 45 and the recessed portion 282 can be set to obtain a fitting strength that can prevent the outer ring 28 from coming off due to its own weight when facing downward.

[0059] Next, the step portion 433 of the column portion 43 will be described. Figure 3In the example of , a stepped portion 433 is provided on the surface of the column 43 facing the rolling element 25. In this case, a gap is formed between the column 43 and the rolling element 25, thereby improving lubricity. The surface of the column 43 facing the rolling element 25 may be a surface orthogonal to the circumferential direction.

[0060] exist Figure 3 In the example of , the step portion 433 extends in a direction inclined relative to the extension direction of the column portion 43 and the direction orthogonal to both the extension direction and the circumferential direction. At this time, the gap with the rolling element 25 is expanded in the extension direction and the orthogonal direction, so the lubricity is improved in a wide range.

[0061] exist Figure 3 In the example, the step portion 433 extends parallel to the axial direction (the direction along the central axis La) of the speed reducer 100. In this case, the gap with the rolling element 25 can be lengthened in the direction along the central axis La. In addition, the mold for resin molding the retainer 40 can be easily processed.

[0062] Next, refer to Figure 3 The inner ring 27 is described below. The inner ring 27 of the first main bearing 24 has a movement restriction portion 273 that restricts the rolling element 25 from moving outward in the axial direction. In this case, the rolling element 25 can be prevented from escaping outward in the axial direction. Figure 3 In the example of FIG. 2 , the movement restricting portion 273 has a flange shape facing the end portion on the large end portion 41 side of the rolling element 25 .

[0063] Next, refer to Figure 3 The outer ring 28 is described. The outer ring 28 of the first main bearing 24 has a retainer movement restriction portion 283 that restricts the retainer 40 from moving inward in the axial direction. At this time, the retainer 40 can be prevented from being disengaged, so the operation of temporarily attaching the retainer 40 to the outer ring 28 becomes easy. Figure 3 In the example of FIG. 2 , the holder movement restricting portion 283 is a protruding portion having a hollow disk shape protruding radially inward.

[0064] Next, the operation of the speed reducer 100 of the above structure will be described. If rotation is transmitted to the eccentric body shaft 12 from a motor or the like, the eccentric portion 128 of the eccentric body shaft 12 rotates around the rotation center line passing through the eccentric body shaft 12, and the external gear 14 is swung via the eccentric body bearing 30. If the external gear 14 swung, the meshing positions of the external gear 14 and the internal gear 16 are sequentially offset. As a result, each time the eccentric body shaft 12 rotates once, one of the external gear 14 and the internal gear 16 rotates by an amount equivalent to the difference in the number of teeth between the external gear 14 and the internal gear 16. In the present embodiment, the external gear 14 rotates, and the reduced rotation is output from the first wheel frame 18 and the second wheel frame 20 via the inner pin 32.

[0065] Next, the features of the speed reducer 100 of the above structure are described. The speed reducer 100 includes a bearing (main bearings 24, 26), the bearing having a retainer 40 for retaining a plurality of rolling elements 25, wherein the retainer 40 has a column 43 for limiting the movement of the plurality of rolling elements 25 in the circumferential direction and an anti-falling portion 44 formed on the column 43 and used to prevent the rolling elements 25 from falling off, and the anti-falling portion 44 is arranged on the inner diameter side and arranged to be biased to one side in the extension direction of the column 43.

[0066] According to this structure, since the anti-dropout portion 44 is arranged to be biased to one side, the lubricant G can be easily supplied to the main bearings 24 and 26 from the side where the anti-dropout portion 44 does not exist. In addition, a gap is formed in the portion where the anti-dropout portion 44 does not exist, and a flow path of the lubricant G can be ensured in the gap.

[0067] The examples of the embodiments of the present invention are described in detail above. The above embodiments are only specific examples for implementing the present invention. The contents of the embodiments are not intended to limit the technical scope of the present invention. Various design changes such as changes, additions, and deletions of constituent elements can be made without departing from the scope of the idea of ​​the invention specified in the claims. In the above embodiments, the contents that can make such design changes are explained by marking "embodiment" and "in the embodiment", but it does not mean that design changes are not allowed without such markings. In addition, the hatched lines marked on the cross-sections of the accompanying drawings are not used to limit the material of the objects marked with hatched lines.

[0068] In the following, a modification example is described. In the drawings and description of the modification example, the same reference numerals are given to the same or equivalent components and parts as those in the embodiment. The description repeated with the embodiment is appropriately omitted, and the structure different from the embodiment is described in detail.

[0069] [Modifications]

[0070] In the above embodiment, the reducer 100 is shown as an example of a so-called center crank type eccentric swing type reducer, but the present invention is not limited to this. The reducer can be any type of reducer as long as it has a main bearing. For example, the reducer can be a so-called distributed eccentric swing type reducer in which a plurality of crankshafts are arranged at positions deviated from the center, or a flexure meshing type reducer such as a cylinder type, a cup type, and a top hat type, or a simple planetary gear type reducer, or various known reducers such as a parallel shaft reducer, a concentric shaft reducer, and an orthogonal shaft reducer.

[0071] In the description of the embodiment, an example is shown in which the inner rings of the main bearings 24 and 26 are formed integrally with the carriers 18 and 20, but the inner rings of the main bearings may be formed separately from the carriers.

[0072] In the description of the embodiment, an example is shown in which the rolling elements 25 of the main bearings 24 and 26 are cylindrical rollers. However, the rolling elements of the main bearings may have a shape different from cylindrical rollers, such as tapered rollers.

[0073] In the description of the embodiment, an example in which the number of the external gears 14 is two is shown, but the number of the external gears may be one or three or more.

[0074] In the description of the embodiment, an example is shown in which the pin member for connecting the wheel carriers 18 and 20 includes the inner pin 32 that helps transmit the driving force of the external gear 14. As the pin member for connecting the wheel carriers 18 and 20, a wheel carrier pin that is different from the inner pin 32 and has nothing to do with the transmission of the driving force may be provided.

[0075] In the description of the embodiment, an example is shown in which the inner pin 32 is formed integrally with the first wheel carrier 18, but the inner pin 32 may be formed separately from the first wheel carrier 18 and connected with a fixing member such as a bolt.

[0076] In the description of the embodiment, an example is shown in which the eccentric bearing 30 does not have an inner ring and an outer ring, but the eccentric bearing 30 may have an inner ring or an outer ring.

[0077] In the description of the embodiment, the main bearings 24 and 26 are exemplified as the bearings described in the claims. However, the bearings described in the claims may be other bearings of the speed reducer such as an eccentric bearing.

[0078] The above-mentioned modifications also have the same functions and effects as those of the above-mentioned embodiment.

[0079] Any combination of the constituent elements and modifications of the above-described embodiments is also effective as an embodiment of the present invention. A new embodiment generated by the combination has the effects of the combined embodiments and modifications.

Claims

1. A speed reducer comprising a bearing, wherein the bearing has a retaining frame for retaining a plurality of rolling elements, wherein: The retainer has a plurality of column portions for limiting the movement of the plurality of rolling elements in the circumferential direction, an anti-falling portion formed on the column portions to prevent the rolling elements from falling off, and a fitting portion fitted with the outer ring of the bearing. The anti-drop portion is arranged on the inner diameter side and is arranged to be closer to the fitting portion in the extending direction of the column portion. Regarding the thickness in a direction passing through the central axis of the reducer and orthogonal to both the extension direction and the circumferential direction of the column portion, the thickness of the side of the column portion where the anti-fall-off portion is arranged on the fitting portion side is greater than the thickness of the side where the anti-fall-off portion is not present.

2. The reducer according to claim 1, characterized in that: The anti-falling portion is arranged to be biased toward a large end portion side having a large outer diameter of a circle described by the axis centers of the plurality of rolling elements.

3. The reducer according to claim 1 or 2, characterized in that: A portion of the anti-falling portion that contacts the curved surface of the rolling element has a curved surface shape.

4. The reducer according to claim 1 or 2, characterized in that: Regarding the thickness in the circumferential direction, the maximum thickness of the column portion on the side where the fall-off preventing portion is present is greater than the maximum thickness of the side where the fall-off preventing portion is not present.

5. The reducer according to claim 1 or 2, characterized in that: The fitting portion is fitted into a recessed portion of the outer ring of the bearing.

6. The reducer according to claim 5, characterized in that: The fitting portion is provided at a large end portion of the retainer between two of the plurality of column portions arranged in a circumferential direction, and is fitted into the recessed portion of the outer ring by elastic deformation.

7. The reducer according to claim 1 or 2, characterized in that: A stepped portion is provided on a surface of the column portion that faces the rolling element.

8. The reducer according to claim 7, characterized in that: The step portion extends in a direction inclined with respect to an extending direction of the column portion and a direction orthogonal to both the extending direction and the circumferential direction.

9. The reducer according to claim 8, characterized in that: The step portion extends parallel to the axial direction of the speed reducer.

10. The reducer according to claim 1 or 2, characterized in that: The inner ring of the bearing has a movement restricting portion that restricts the rolling element from moving outward in the axial direction.

11. The reducer according to claim 1 or 2, characterized in that: The outer ring of the bearing has a cage movement restricting portion that restricts the cage from moving inward in the axial direction.

12. The reducer according to claim 1 or 2, characterized in that: The invention also comprises an internal gear provided on the housing, an external gear meshing with the internal gear, and a wheel carrier arranged on a side portion of the external gear in the axial direction. The bearing is arranged between the housing and the wheel carrier.

13. A cage, which is a cage for holding a bearing of a plurality of rolling elements, wherein the cage has: A plurality of column portions, which restrict the plurality of rolling elements from moving in a circumferential direction; an anti-falling portion formed on the column portion to prevent the rolling element from falling off; and A fitting portion is fitted with the outer ring of the bearing, The anti-drop portion is arranged on the inner diameter side and is arranged to be closer to the fitting portion in the extending direction of the column portion. Regarding the thickness in a direction passing through the central axis of the bearing and orthogonal to both the extension direction and the circumferential direction of the column portion, the thickness of the side of the column portion where the anti-fall-off portion is arranged on the fitting portion side is greater than the thickness of the side where the anti-fall-off portion is not present.

14. A bearing having a retaining frame for retaining a plurality of rolling elements, wherein: The retainer has a plurality of column portions for limiting the movement of the plurality of rolling elements in the circumferential direction, an anti-falling portion formed on the column portions to prevent the rolling elements from falling off, and a fitting portion fitted with the outer ring of the bearing. The anti-drop portion is arranged on the inner diameter side and is arranged to be closer to the fitting portion in the extending direction of the column portion. Regarding the thickness in a direction passing through the central axis of the bearing and orthogonal to both the extension direction and the circumferential direction of the column portion, the thickness of the side of the column portion where the anti-fall-off portion is arranged on the fitting portion side is greater than the thickness of the side where the anti-fall-off portion is not present.

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