Flexible gears, wave reducers, and robots

Abstract

To lubricate external teeth of a flexible gear to improve wear resistance.SOLUTION: A flexible gear 40 has a flexible trunk part 41 extending axially around a central axis 9, and a first oil-containing member 44 containing lubricant. The trunk part 41 has a first cylindrical trunk part 411 extending axially, and a second cylindrical trunk part 412 arranged on one side of the first trunk part in an axial direction and extending axially. The radially inner surface of the first oil-containing member 44 contacts the radially outer surface of the first trunk part 411. The second trunk part 412 has a plurality of external teeth 400 protruding radially outward from the radially outer surface. Consequently, when the flexible gear 40 is flexibly deformed, the lubricant seeps out from the first oil-containing member 44 to lubricate the external teeth 400.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flexible gear, a wave reducer, and a robot. [Background technology]

[0002] BACKGROUND ART Conventionally, a strain wave gear device that is mainly used in a reducer is known (Patent Document 1). [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-132726 Summary of the Invention [Problem to be solved by the invention]

[0003] In conventional gear devices and harmonic reducers, in order to improve the wear resistance of the tooth surfaces of the external teeth of the flexspline (flexible gear) and the internal teeth of the circular spline (internal gear), which mesh with each other, the tooth surfaces of the external teeth of the flexspline and the tooth surfaces of the internal teeth of the circular spline are formed from a specific type of resin.

[0004] However, molding a flexible gear from resin poses the problem of lower molding accuracy compared to a metal flexible gear. Changing the materials for the flexible gear and the internal gear also poses other problems, such as the need to introduce new manufacturing equipment. Therefore, it is preferable to improve the wear resistance of the external teeth of the flexible gear by lubricating the external teeth of the flexible gear without changing the materials of the conventional flexible gear and the internal gear.

[0005] An object of the present invention is to provide a technology capable of lubricating the external teeth of a flexible gear. [Means for solving the problem]

[0006] According to an exemplary embodiment of the present application, there is provided a flexible gear having a flexible body portion extending axially around a central axis and a first oil-retaining member containing lubricating oil. The body portion has a cylindrical first body portion extending axially and a cylindrical second body portion extending axially and disposed on one axial side of the first body portion. The radially inner surface of the first oil-retaining member contacts the radially outer surface of the first body portion. The second body portion has a plurality of external teeth protruding radially outward from its radially outer surface. [Effects of the Invention]

[0007] According to the flexible gear according to the exemplary embodiment of the present application, when the flexible gear undergoes flexibly deformation, lubricating oil seeps out from the first oil-retaining member, lubricating the external teeth. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view of a wave reducer according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the wave reducer according to the first embodiment. [Figure 3] FIG. 3 is a partial vertical cross-sectional view of the wave reducer according to the first embodiment. [Figure 4] FIG. 4 is a partial vertical cross-sectional view of the wave reducer according to the first embodiment. [Figure 5] FIG. 5 is a perspective view of the first oil-retaining member according to the first embodiment. [Figure 6] FIG. 6 is a perspective view of the flexible bearing according to the first embodiment. [Figure 7] FIG. 7 is a perspective view of the second oil-retaining member according to the first embodiment. [Figure 8] FIG. 8 is a perspective view of a first oil-retaining member according to a modified example. [Figure 9] FIG. 9 is a partial plan view of a first oil-retaining member according to a modified example. [Figure 10] FIG. 10 is a perspective view of a flexible bearing according to a modified example. [Figure 11] FIG. 11 is a perspective view of a second oil-retaining member according to a modified example. [Figure 12] FIG. 12 is a perspective view of a third oil-retaining member according to a modified example. [Figure 13] FIG. 13 is a perspective view of a robot equipped with a wave reducer. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, exemplary embodiments of the present application will be described with reference to the drawings. In this application, a direction parallel to the central axis of a wave reducer is referred to as the "axial direction," a direction perpendicular to the central axis of the wave reducer is referred to as the "radial direction," and a direction along an arc centered on the central axis of the wave reducer is referred to as the "circumferential direction." However, the above-mentioned "parallel direction" also includes a direction that is approximately parallel. Furthermore, the above-mentioned "orthogonal direction" also includes a direction that is approximately orthogonal.

[0010] 1. First Embodiment <1-1. Overall configuration of the wave reducer> Fig. 1 is a longitudinal sectional view of a wave reducer 1 according to a first embodiment. Fig. 1 is a sectional view taken along the line AO-A' in Fig. 2. Fig. 2 is a transverse sectional view of the wave reducer 1. Fig. 2 is a sectional view taken along the line BB in Fig. 1.

[0011] The wave reducer 1 is a device that changes (decelerates) rotational motion at a first rotational speed obtained from a motor to rotational motion at a second rotational speed that is lower than the first rotational speed, and transmits the rotational motion to a downstream stage. The wave reducer 1 is used, for example, by being incorporated into a joint of a small robot together with a motor. However, the wave reducer of the present invention may also be used in other devices such as an assist suit, a turntable, an indexing plate for a machine tool, a wheelchair, and an unmanned guided vehicle.

[0012] The wave reducer 1 has a wave generator 20, a flexible bearing 30, a flexible gear 40, and an internal gear 50. As shown in Figures 1 and 2, the wave reducer 1 of this embodiment has an input member 10, the wave generator 20, the flexible bearing 30, the flexible gear 40, the internal gear 50, a first housing 60, a second housing 70, and a roller bearing 80.

[0013] The input member 10 is a part that rotates at a first rotational speed before deceleration. In this embodiment, the input member 10 is cylindrical and extends along a central axis 9. The input member 10 may be a motor shaft, or may be a member that is connected to a motor (not shown) directly or via a power transmission mechanism such as a gear. When the motor is driven, the input member 10 rotates around the central axis 9 at a first rotational speed.

[0014] The wave generator 20 is a mechanism that generates periodic bending deformation in a second body portion 412 (described later) of the flexible gear 40. The wave generator 20 is rotatable about a central axis 9. When the above-mentioned motor is driven, the wave generator 20 together with the input member 10 rotates about the central axis 9 at a first rotational speed. The wave generator 20 of this embodiment is an elliptical cam. The input member 10 and the wave generator 20 may be formed as a single member as shown in FIG. 1 , or may be separate members.

[0015] The flexible bearing 30 is disposed between the wave generator 20 and the flexible gear 40. The flexible bearing 30 connects the radially outer surface of the wave generator 20 and the radially inner surface of the second body 412 so as to be able to rotate relative to each other. The flexible bearing 30 is able to displace radially in response to the rotation of the wave generator 20.

[0016] The flexible bearing 30 has a flexible inner ring 31, a flexible outer ring 32, and a plurality of balls 33. The flexible bearing 30 is a ball bearing. The flexible inner ring 31 is fixed to the radially outer surface of the wave generator 20. The radially inner surface of the flexible inner ring 31 is fixed to the radially outer surface of the wave generator 20. The radially outer surface of the flexible outer ring 32 is fixed to the radially inner surface of the second body portion 412 of the flexible gear 40. The plurality of balls 33 are rotatably arranged between the flexible inner ring 31 and the flexible outer ring 32. The detailed configuration of the flexible bearing 30 will be described later.

[0017] The flexible gear 40 is a thin, annular gear that is flexible and deformable. In this embodiment, the flexible gear 40 has a substantially elliptical shape in a cross section perpendicular to the central axis 9. The flexible gear 40 is supported so as to be rotatable about the central axis 9. The flexible gear 40 of this embodiment has a body portion 41, a flange portion 42, a fixing portion 43, and a first oil-impregnated member 44. The body portion 41 is flexible and extends in the axial direction about the central axis 9. The first oil-impregnated member 44 contains lubricating oil. That is, the flexible gear 40 has the flexible body portion 41 that extends in the axial direction about the central axis 9, and the first oil-impregnated member 44 that contains lubricating oil. The first oil-impregnated member 44 will be described later.

[0018] Body 41 extends in the axial direction in a cylindrical shape centered on central axis 9. Body 41 has a first body 411 and a second body 412. First body 411 and second body 412 are both cylindrical and extend in the axial direction. Second body 412 is disposed on one axial side of first body 411. One axial side is the direction from first housing 60 toward second housing 70. In the drawings, one axial side is indicated as D1, and the other axial side is indicated as D2.

[0019] The flexible gear 40 has a flange portion 42. The flange portion 42 is an annular portion that extends radially outward from the other axial end of the body portion 41. The fixed portion 43 is a portion that extends radially outward from the radially outer end of the flange portion 42. The axial thickness of the fixed portion 43 is greater than the axial thickness of the flange portion 42. The fixed portion 43 is fixed to the first housing 60 and an outer ring 82 of the roller bearing 80, which will be described later.

[0020] The body portion 41 is flexible and therefore capable of radial deformation. In particular, the second body portion 412 is the tip end of the body portion 41 and is a free end, and therefore is capable of greater radial displacement than the first body portion 411. On the other hand, the first body portion 411 becomes less susceptible to radial deformation as it approaches the other axial end of the body portion 41. Furthermore, as the body portion 41 deforms, the flange portion 42 undergoes slight axial deformation, but the fixing portion 43 undergoes almost no deformation.

[0021] 1 and 2, the flexible gear 40 has a plurality of external teeth 400. Specifically, the second body portion 412 has a plurality of external teeth 400 that protrude radially outward from the radially outer surface. The plurality of external teeth 400 are also arranged at a constant pitch in the circumferential direction.

[0022] The second body portion 412 is pressed radially outward via the flexible outer ring 32 of the flexible bearing 30 at two circumferential positions that are the same as the circumferential position of the major axis of the elliptical wave generator 20. This causes the second body portion 412 to bend and deform into an elliptical shape. As a result, the external teeth 400 provided on the second body portion 412 mesh with the internal teeth 500 of the internal gear 50, which will be described later, at two circumferential positions that correspond to the major axis of the ellipse. Hereinafter, the circumferential positions at which the external teeth 400 and the internal teeth 500 mesh are referred to as "meshing positions."

[0023] The internal gear 50 is substantially annular and centered on the central axis 9. The internal gear 50 is fixed to the second housing 70, for example, by screws. The rigidity of the internal gear 50 is much higher than the rigidity of the body portion 41 of the flexible gear 40. Therefore, the internal gear 50 can be considered to be a substantially rigid body. The internal gear 50 has a plurality of internal teeth 500. The plurality of internal teeth 500 protrude radially inward from the radially inner surface of the internal gear 50. The plurality of internal teeth 500 are also arranged at a constant pitch in the circumferential direction.

[0024] The internal gear 50 is disposed radially outward of the second body portion 412. In other words, the internal gear 50 is disposed radially outward of the second body portion 412, and has a plurality of internal teeth 500 arranged in the circumferential direction.

[0025] The number of external teeth 400 of the flexible gear 40 described above and the number of internal teeth 500 of the internal gear 50 are slightly different.

[0026] The wave reducer 1 has a housing that is disposed on the other axial side of the flexible gear 40 and to which the flexible gear 40 is fixed. The first housing 60 is an example of the housing. The first housing 60 is disposed on the other axial side of the flexible gear 40. The first housing 60 has a cylindrical portion 61 and a cover portion 62.

[0027] The cylindrical portion 61 is a substantially cylindrical portion extending along the central axis 9. One axial end of the cylindrical portion 61 is disposed radially inward of the first body portion 411 of the flexible gear 40. The other axial end of the cylindrical portion 61 is disposed on the other axial side of the flexible gear 40. A bearing 11 is disposed between the radial inner surface of the cylindrical portion 61 and the radial outer surface of the input member 10. This allows the input member 10 to rotate relative to the first housing 60.

[0028] The cover portion 62 extends radially outward from the other axial end of the cylindrical portion 61. The cover portion 62 is an annular portion that surrounds the central axis 9. When viewed from the other axial side, the cover portion 62 overlaps the entire flexible gear 40. The flexible gear 40 is fixed to the first housing 60. Specifically, the fixed portion 43 of the flexible gear 40 is sandwiched between the cover portion 62 of the first housing 60 and the outer ring 82, and fixed by a fastening member such as a screw.

[0029] The second housing 70 is disposed on one axial side of the internal gear 50. The second housing 70 is annular about a central axis 9. When viewed from one axial side, the second housing 70 overlaps the entire internal gear 50. The internal gear 50 is fixed to the second housing 70. Specifically, the internal gear 50 is sandwiched between the second housing 70 and an inner ring 81 of a roller bearing 80 (described later), and fixed with a fastening member such as a screw. In addition, a bearing 12 is disposed between a radially inner surface of the second housing 70 and a radially outer surface of the input member 10. This allows the input member 10 to be rotatably supported relative to the second housing 70.

[0030] The roller bearing 80 is disposed radially outward from the first body portion 411. The roller bearing 80 has an inner ring 81, an outer ring 82, and a plurality of rolling elements 83 sandwiched between the inner ring 81 and the outer ring 82. As described above, the inner ring 81 of the roller bearing 80 is fixed to the internal gear 50. More specifically, the inner ring 81 of the roller bearing 80 is fixed to the internal gear 50 and the second housing 70. The outer ring 82 of the roller bearing 80 is fixed to the flexible gear 40. More specifically, the outer ring 82 of the roller bearing 80 is fixed to the fixed portion 43 of the flexible gear 40 and the cover portion 62 of the first housing 60. In this way, the roller bearing 80 connects the flexible gear 40 and the first housing 60 with the internal gear 50 and the second housing 70 so that they can rotate relative to each other.

[0031] In this embodiment, the first housing 60 is an output member of the wave reducer 1. When the first housing 60 is used as an output member, the second housing 70 is fixed, for example, by screws, to the frame of the device on which the wave reducer 1 is mounted. When the wave generator 20 rotates at a first rotational speed, the long axis of the flexible gear 40 also rotates at the first rotational speed. As a result, the meshing position between the external teeth 400 and the internal teeth 500 also changes circumferentially at the first rotational speed. As described above, the number of external teeth 400 of the flexible gear 40 and the number of internal teeth 500 of the internal gear 50 are slightly different. Due to this difference in the number of teeth, the meshing position between the external teeth 400 and the internal teeth 500 changes slightly circumferentially with each rotation of the wave generator 20. As a result, the flexible gear 40 rotates relative to the internal gear 50 about the central axis 9 at a second rotational speed lower than the first rotational speed. Therefore, rotational motion at a reduced second rotational speed is output from the first housing 60, which rotates at the same rotational speed as the flexible gear 40. In other words, the first housing 60 serves as an output part that rotates together with the flexible gear 40.

[0032] It is also possible to use the second housing 70 as an output member. When using the second housing 70 as an output member, the first housing 60 is fixed, for example with screws, to the frame of the device on which the wave reducer 1 is mounted. In this case, when the wave generator 20 rotates at a first rotational speed, the internal gear 50 rotates around the central axis 9 relative to the flexible gear 40 at a second rotational speed that is lower than the first rotational speed. Therefore, rotational motion at the reduced second rotational speed is output from the second housing 70, which rotates at the same rotational speed as the internal gear 50.

[0033] <1-2. First oil-retaining member> Next, the first oil-retaining member 44 will be described with reference to Fig. 1 and Figs. 3 to 5. Fig. 3 and Fig. 4 are partial vertical cross-sectional views of the wave reducer 1. Fig. 3 is a cross-sectional view in OA section, which is not the meshing position between the external teeth 400 and the internal teeth 500. Fig. 4 is a cross-sectional view in OA' section, which is the meshing position between the external teeth 400 and the internal teeth 500. Fig. 5 is a perspective view of the first oil-retaining member 44.

[0034] The first oil-retaining member 44 is a member containing lubricating oil. In this embodiment, the resin molded product that forms the first oil-retaining member 44 is formed by mixing a resin material and lubricating oil, injecting the mixture into a mold, and then heat treating it. This results in a resin molded product with many fine cavities inside. The lubricating oil is stored in the cavities, resulting in an oil-retaining member from which the lubricating oil seeps out due to external force or surface tension. However, the first oil-retaining member may be formed by other manufacturing methods.

[0035] 3 and 4, the radially inner surface of the first oil-retaining member 44 contacts the radially outer surface of the first body portion 411. As shown in Fig. 3, the body portion 41 does not bend radially outward at the position in the circumferential direction farthest from the meshing position between the external teeth 400 and the internal teeth 500. Therefore, the first oil-retaining member 44 also hardly bends, and lubricating oil does not easily seep out.

[0036] 4, at the meshing position between the external teeth 400 and the internal teeth 500 in the circumferential direction, the body portion 41 bends radially outward. As a result, the first oil-retaining member 44 is pushed radially outward by the body portion 41 and bends. Therefore, at the meshing position, the first oil-retaining member 44 elastically deforms, causing a small amount of lubricating oil that has soaked into the interior to seep out. The seeped lubricating oil travels along the outer surface of the body portion 41 to lubricate the external teeth 400.

[0037] In this way, the external teeth 400 are lubricated when the flexible gear 40 flexibly deforms. The lubrication effect is particularly pronounced at the meshing positions of the external teeth 400 and the internal teeth 500. Furthermore, since the wave reducer 1 has the flexible gear 40, the external teeth of the flexible gear 40 can be lubricated, and the wave reducer 1 can be driven for a long period of time.

[0038] 3 and 4, the axial position of the end portion on one axial side of the first oil-retaining member 44 is the same as the axial position of the end portion on the other axial side of the external tooth 400. That is, the end portion on one axial side of the first oil-retaining member 44 faces the end portion on the other axial side of the external tooth 400 in the radial direction. This prevents the first oil-retaining member 44 from moving to one axial side. Furthermore, surface tension allows the lubricating oil in the first oil-retaining member 44 to easily penetrate into the external tooth 400.

[0039] 5, the first oil-retaining member 44 has a cylindrical shape extending in the axial direction. As a result, the first oil-retaining member 44 surrounds the radially outer surface of the first body portion 411. As a result, the external teeth 400 can be lubricated over the entire circumference of the second body portion 412.

[0040] As shown in FIGS. 3 and 4, the first oil-retaining member 44 has a cylindrical portion 441 , a tapered portion 442 , and a protruding portion 443 .

[0041] The cylindrical portion 441 is a substantially cylindrical portion. The tapered portion 442 is disposed at one axial end of the first oil-retaining member 44. The radially inner surface of the cylindrical portion 441 is in contact with the radially outer surface of the first body portion 411. This determines the radial position of the first oil-retaining member 44.

[0042] The radially inner surface of the tapered portion 442 slopes radially outward as it extends toward one axial side. As shown in Fig. 4, at the meshing position between the external teeth 400 and the internal teeth 500, the first body portion 411 is flexibly deformed mainly near its one axial end. That is, the first oil-retaining member 44 is also likely to be flexibly deformed most significantly near its one axial end, as indicated by the dashed arrow in Fig. 4. Therefore, the one radial end of the first oil-retaining member 44 is tapered radially outward, which is the deformation direction, to prevent excessive lubricating oil from seeping out due to large flexible deformation.

[0043] The protruding portion 443 protrudes radially outward from the radially outer surface of the cylindrical portion 441 at the end portion on the other axial side of the cylindrical portion 441. The end portion on the other axial side of the protruding portion 443 is in axial contact with the surface on one axial side of the flange portion 42. That is, the end portion on the other axial side of the first oil-retaining member 44 is in axial contact with the surface on one axial side of the flange portion 42. This prevents the first oil-retaining member 44 from moving in the other axial direction.

[0044] The first oil-retaining member 44 has a protrusion 443 that protrudes radially outward from the radially outer surface. The radially outer end of the protrusion 443 comes into radial contact with the radially inner surface of the inner ring 81 of the roller bearing 80. This allows the first oil-retaining member 44 to be supported from both radial sides by the first body portion 411 and the inner ring 81. This more reliably positions the first oil-retaining member 44 in the radial direction. Meanwhile, by having the protrusion 443, which is located on only a portion of the axial direction, serve as the contact point with the inner ring 81 of the roller bearing 80, the contact area between the inner ring 81 and the first oil-retaining member 44, which rotate relative to each other, is reduced, thereby suppressing power loss.

[0045] The first oil-bearing member 44 has one or more notches extending axially from one axial end or the other axial end. In this embodiment, as shown in Fig. 5, the first oil-bearing member 44 has multiple notches 91, 92. In this embodiment, the first oil-bearing member 44 has one first notch 91 and multiple second notches 92. The number of second notches 92 is 19.

[0046] The first notch 91 separates the first oil-retaining member 44 from its end on one axial side to its end on the other axial side. In other words, the notches include the first notch 91 that separates the first oil-retaining member 44 from its end on one axial side to its end on the other axial side. Since the first oil-retaining member 44 has only one such first notch 91, the first oil-retaining member 44 can be expanded into a C-shape when viewed in the axial direction. This makes it easy to attach the first oil-retaining member 44 to the trunk portion 41 in the manufacturing process of the flexible gear 40.

[0047] The second notch 92 extends from an end portion on one axial side of the first oil-retaining member 44 to a position on one axial side of the end portion on the other axial side of the first oil-retaining member 44. Specifically, the end portion on the other axial side of the second notch 92 is on one axial side of the protruding portion 443.

[0048] In this way, by having the axially extending notches 91, 92, the first oil-retaining member 44 is likely to flexibly deform in accordance with the flexible deformation of the trunk portion 41 of the flexible gear 40. In other words, it is difficult to suppress the flexible deformation of the trunk portion 41. In addition, the notches 91, 92 also allow the lubricating oil to seep out of the first oil-retaining member 44 smoothly.

[0049] In this embodiment, the total number of notches 91, 92 is 20. The number of notches 91, 92 is less than the number of external teeth 400. The notches 91, 92 are arranged at equal intervals in the circumferential direction. This makes the first oil-retaining member 44 more uniform in its deformation tendency in the circumferential direction. Therefore, the seepage of lubricating oil from the first oil-retaining member 44 also becomes more uniform in the circumferential direction.

[0050] <1-3. Second oil-retaining member> Next, the second oil-retaining member 34 will be described with reference to Figures 6 and 7. Figure 6 is a perspective view of the flexible bearing 30. Figure 7 is a perspective view of the second oil-retaining member 34.

[0051] As shown in Fig. 6, the flexible bearing 30 of this embodiment has a second oil-retaining member 34 disposed between the flexible inner ring 31 and the flexible outer ring 32. As shown in Fig. 7, the second oil-retaining member 34 is an annular member. In this embodiment, the second oil-retaining member 34 has a substantially circular ring shape. The second oil-retaining member 34 is formed, for example, in the same manner as the first oil-retaining member 44, by molding a material obtained by mixing a resin material and a lubricating oil.

[0052] As shown in FIG. 7 , the second oil-retaining member 34 has a plurality of first recesses 341 and a plurality of second recesses 342. In this embodiment, the second oil-retaining member 34 further has a plurality of hollow portions 343. The plurality of first recesses 341 extend from the radially outer side toward the radially inner side. More specifically, each of the first recesses 341 extends from the radially outer surface of the second oil-retaining member 34 toward the radially inner side. The plurality of second recesses 342 extend from the radially inner side toward the radially outer side. More specifically, each of the second recesses 342 extends from the radially inner surface of the second oil-retaining member 34 toward the radially outer side. A ball 33 is disposed in each of the hollow portions 343.

[0053] The multiple first recesses 341 and the multiple second recesses 342 are arranged alternately in the circumferential direction. A hollow portion 343 is arranged between the first recesses 341 and the second recesses 342 that are adjacent in the circumferential direction. In this embodiment, the number of balls 33 (i.e., the number of hollow portions 343) is 23, which is an odd number. Therefore, there is one location where two first recesses 341 are adjacent in the circumferential direction with the hollow portion 343 sandwiched between them.

[0054] In this way, by disposing the second oil-retaining member 34 in the space between the flexible inner ring 31 and the flexible outer ring 32, the flexible bearing 30 is lubricated, and power loss in the flexible bearing 30 is reduced.

[0055] Furthermore, by arranging the multiple first recesses 341 and the multiple second recesses 342 alternately in the circumferential direction, the second oil-retaining member 34 easily expands and contracts in the radial direction like a bellows. Therefore, even if the second oil-retaining member 34 is arranged between the flexible inner ring 31 and the flexible outer ring 32, it is difficult to suppress radial deformation of the flexible inner ring 31 and the flexible outer ring 32.

[0056] <1-4. Third oil-retaining member> Next, the third oil-retaining member 35 will be described with reference to Figures 1, 3 and 4. As shown in Figures 1, 3 and 4, the wave reducer 1 of this embodiment has the third oil-retaining member 35 arranged radially inside the body portion 41.

[0057] The third oil-retaining member 35 of this embodiment is a cylindrical member. The third oil-retaining member 35 is formed, for example, in the same manner as the first oil-retaining member 44, by molding a material made by mixing a resin material and a lubricating oil. The third oil-retaining member 35 is arranged along the radially inner surface of the body portion 41. One axial end face of the third oil-retaining member 35 contacts the other axial end face of the flexible bearing 30 in the axial direction. This allows the flexible bearing 30 to be lubricated by the lubricating oil seeping out from the third oil-retaining member 35. Furthermore, the third oil-retaining member 35 and the flexible bearing 30 can be positioned in the axial direction.

[0058] Furthermore, the end face on the other axial side of the third oil-retaining member 35 is in axial contact with a surface on one axial side of the housing. The first housing 60 is an example of the above-mentioned housing. That is, the end face on the other axial side of the third oil-retaining member 35 is in axial contact with a surface on one axial side of the cylindrical portion 61 of the first housing 60. This prevents the third oil-retaining member 35 from shifting toward the other axial side.

[0059] The first oil-retaining member 44 and the third oil-retaining member 35 are arranged in a radially overlapping position in at least a portion of their axial regions. That is, a portion of the first oil-retaining member 44 and a portion of the third oil-retaining member 35 face each other in the radial direction, sandwiching the body portion 41 therebetween. This provides a good weight balance between the radially inner and outer sides of the body portion 41. Furthermore, by using a common axial region for arranging the first oil-retaining member 44 that lubricates the external teeth 400 and the third oil-retaining member 35 that lubricates the flexible bearing 30, it is possible to lubricate both the external teeth 400 and the flexible bearing 30 without increasing the axial length of the wave reducer 1.

[0060] <2. Modifications> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0061] <2-1. First modified example> Fig. 8 is a perspective view of a first oil-retaining member 44A according to a modified example. Fig. 9 is a partial plan view of a part of the first oil-retaining member 44A as viewed from one axial side. This first oil-retaining member 44A can be used in place of the first oil-retaining member 44 in the wave reducer 1 of the above embodiment.

[0062] The first oil-retaining member 44A has a plurality of first protrusions 444A protruding radially outward and a plurality of second protrusions 445A protruding radially inward. The first protrusions 444A and the second protrusions 445A are arranged alternately in the circumferential direction. That is, the first oil-retaining member 44A has a bellows-like shape. This makes it easy to expand and contract the first oil-retaining member 44A in the radial direction. This makes it easy to attach the first oil-retaining member 44A to the radially outer surface of the body 41.

[0063] 8 and 9, near the other axial end portion, the radially outer end portion of the first protrusion 444A protrudes in a V-shape. This portion becomes the protrusion 443A. The protrusion 443A comes into radial contact with the radially inner surface of the inner ring 81.

[0064] At an axial position other than the protrusion 443A, the radially outer end of the first convex portion 444A forms an outer chamfered surface 446A along a cylindrical surface having a smaller diameter than the radially outer end of the protrusion 443A.

[0065] Additionally, the radially inner end of second convex portion 445A includes inner chamfered surface 447A and tapered surface 448A. Inner chamfered surface 447A follows a cylindrical surface with a smaller diameter than outer chamfered surface 446A. The axial region of first oil-retaining member 44A including outer chamfered surface 446A and inner chamfered surface 447A corresponds to cylindrical portion 441 in the above embodiment.

[0066] The tapered surface 448A is disposed at one axial end of the first oil-retaining member 44A. The tapered surface 448A slopes outward in the axial direction from one axial end of the inner chamfered surface 447A toward one axial side. The axial region of the first oil-retaining member 44A including the outer chamfered surface 446A and the tapered surface 448A corresponds to the tapered portion 442 in the above embodiment.

[0067] Since the first oil-retaining member 44A is bellows-shaped, it can be easily expanded or contracted in the radial direction, which makes it easy to attach the first oil-retaining member 44A to the trunk portion 41 even if it does not have a cut portion such as the first notch 91 of the first oil-retaining member 44 of the above embodiment.

[0068] <2-2. Second modified example> Fig. 10 is a perspective view of a flexible bearing 30B having a second oil-retaining member 34B according to a modified example. Fig. 11 is a perspective view of the second oil-retaining member 34B. The flexible bearing 30B can be used in place of the flexible bearing 30 in the wave reducer 1 of the above embodiment. The flexible inner ring 31, flexible outer ring 32, and multiple balls 33 of the flexible bearing 30B shown in Fig. 10 are the same as those in the above embodiment, and therefore description thereof will be omitted.

[0069] As shown in FIG. 11 , the second oil-retaining member 34B has an annular portion 344B and multiple columnar portions 345B. The annular portion 344B is an annular portion. The annular portion 344B is arranged on the other axial side of the multiple balls 33 in the space between the flexible inner ring 31 and the flexible outer ring 32. Each columnar portion 345B extends from the annular portion 344B to one axial side. The columnar portions 345B and the balls 33 are arranged alternately in the circumferential direction. This allows each columnar portion 345B to lubricate the balls 33 adjacent to them in the circumferential direction.

[0070] 10 and 11, each of the columnar portions 345B has a quadrangular columnar shape, but the shape of the columnar portion 345B is not limited to this. For example, the circumferential surface of the columnar portion 345B may be a curved surface that follows the shape of the balls 33 adjacent to each other in the circumferential direction.

[0071] 10 and 11, the annular portion 344B is disposed on the other axial side, but the present invention is not limited to this. The annular portion 344B may be disposed on one axial side.

[0072] <2-3.Third modified example> 12 is a perspective view of a third oil-retaining member 35C according to a modified example. The third oil-retaining member 35C can be used in place of the third oil-retaining member 35 in the wave reducer 1 of the above embodiment.

[0073] The third oil-retaining member 35C has a plurality of outer convex portions 351C that protrude radially outward and a plurality of inner convex portions 352C that protrude radially inward. The outer convex portions 351C and the inner convex portions 352C are alternately arranged in the circumferential direction. That is, the third oil-retaining member 35C has a bellows-like shape.

[0074] 12, the radially outer end of the outer convex portion 351C is slightly chamfered and V-shaped. The radially outer end of the outer convex portion 351C is disposed along the radially inner side surface of the body portion 41. Furthermore, the radially inner end of the inner convex portion 352C is also slightly chamfered and V-shaped.

[0075] The third oil-retaining member 35C is bellows-shaped and therefore can be easily expanded or contracted in the radial direction, which makes it easy to attach the third oil-retaining member 35C to a predetermined position during the manufacturing process of the wave reducer.

[0076] <2-4. Other variations> In the above embodiment, the wave reducer 1 has the first oil-retaining member 44 that lubricates the external teeth 400, as well as the second oil-retaining member 34 and the third oil-retaining member 35 that lubricate the flexible bearing 30, but the present invention is not limited to this. The first oil-retaining member 44, the second oil-retaining member 34, and the third oil-retaining member 35 may each be used independently.

[0077] 3. Robot 13 is a perspective view of a robot 100 equipped with a wave reducer 1. The robot 100 is a so-called industrial robot that performs tasks such as transporting, processing, and assembling parts on, for example, an industrial product manufacturing line. The robot 100 has the wave reducer 1, a motor 13, a base frame 101, and an arm 102 that serves as an output unit.

[0078] The output shaft of the motor 13 is fixed to the input member 10 of the wave reducer 1. As a result, the motor 13 provides rotational power to the wave generator 1. The arm 102 is fixed to the first housing 60. As a result, the arm 102, which is the output part, can rotate together with the flexible gear 40. When the motor 13 is driven, the input member 10 rotates together with the output shaft of the motor 13 at a first rotational speed. Then, the arm 102 rotates together with the first housing 60 and the flexible gear 40 at a second rotational speed.

[0079] As described above, the robot 100 has the wave reducer 1, the motor 13 that provides rotational power to the wave generator, and an output section that can rotate together with the flexible gear 40. This allows the external teeth 400 of the flexible gear 40 of the wave reducer 1 mounted on the robot 100 to be lubricated by the first oil-retaining member 44. This makes it possible to operate the wave reducer 1 and the robot for a long period of time.

[0080] In addition, the detailed configuration of the wave reducer may be modified as appropriate without departing from the spirit of the present invention. Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate as long as no contradictions arise. [Industrial Applicability]

[0081] The present application can be used in flexible gears, wave reducers, and robots. [Explanation of symbols]

[0082] 1 Wave reducer 9 Center axis 13 Motor 20 Wave Generator 30,30B flexible bearing 31 Flexible inner ring 32 Flexible outer ring 33 balls 34,34B 2nd oil-impregnated member 35,35C 3rd oil-impregnated member 40 Flexible Gear 41 Torso 42 Flange 44,44A 1st oil-impregnated member 50 Internal gear 60 1st Housing 80 Roller bearing 81 Inner circle 82 outer ring 91 First cut 92 Second cut 100 robots 102 Arm 341 First recess 342 Second recess 351C Outer convex part 352C Inner convex part 400 outer teeth 411 First Body 412 Second body 443,443A Projection 444A First convex part 445A Second convex part 500 inner teeth

Claims

1. A flexible gear, a flexible body portion extending in an axial direction about a central axis; a first oil-retaining member containing lubricating oil; and The body portion is a cylindrical first body portion extending in an axial direction; a cylindrical second body portion extending in the axial direction and disposed on one axial side of the first body portion; and a radially inner surface of the first oil-retaining member contacts a radially outer surface of the first body portion, the second body portion has a plurality of external teeth protruding radially outward from a radially outer surface, A flexible gear in which the axial position of one axial end of the first oil-retaining member is the same as the axial position of the other axial end of the external teeth.

2. 2. The flexible gear according to claim 1, The first oil-retaining member is a cylindrical portion whose radially inner surface contacts the radially outer surface of the first body portion; a tapered portion disposed at one axial end of the first oil-retaining member and having a radially inner surface that slopes radially outward as it approaches the one axial end; A flexible gear having a

3. A flexible gear, a flexible body portion extending in an axial direction about a central axis; a first oil-retaining member containing lubricating oil; and The body portion is a cylindrical first body portion extending in an axial direction; a cylindrical second body portion extending in the axial direction and disposed on one axial side of the first body portion; and a radially inner surface of the first oil-retaining member contacts a radially outer surface of the first body portion, the second body portion has a plurality of external teeth protruding radially outward from a radially outer surface, the first oil-retaining member has a cylindrical shape extending in the axial direction, The first oil-retaining member is a flexible gear having one or more notches extending axially from one axial end or the other axial end.

4. 4. The flexible gear according to claim 3, The flexible gear includes a first notch that separates the first oil-retaining member from one axial end to the other axial end.

5. The flexible gear according to claim 3 or 4, the first oil-retaining member has a plurality of the cuts, The flexible gear includes a second notch extending from one axial end of the first oil-retaining member to a position on one axial side of the other axial end of the first oil-retaining member.

6. 6. The flexible gear according to claim 5, the number of the notches is less than the number of the external teeth; The flexible gear has a plurality of notches arranged at equal intervals in the circumferential direction.

7. The flexible gear according to any one of claims 1 to 6, a flange portion extending radially outward from the other axial end of the barrel portion, A flexible gear in which the other axial end of the first oil-retaining member is in axial contact with the surface of the flange portion on one axial side.

8. The flexible gear according to any one of claims 1 to 7, The first oil-retaining member is a plurality of first protrusions protruding radially outward; a plurality of second protrusions protruding radially inward; and The flexible gear is configured such that the first protrusions and the second protrusions are alternately arranged in a circumferential direction.

9. A flexible gear according to any one of claims 1 to 8; a wave generator rotatable around the central axis; a flexible bearing that connects a radially outer surface of the wave generator and a radially inner surface of the second body portion so as to be rotatable relative to each other; an internal gear disposed radially outward of the second body portion and having a plurality of internal teeth arranged in a circumferential direction; A wave reducer having

10. The wave reducer according to claim 9, The flexible bearing comprises: an inner ring fixed to a radially outer surface of the wave generator; an outer ring fixed to a radially inner surface of the second body portion; a plurality of balls rotatably disposed between the inner ring and the outer ring; a second oil-retaining member disposed between the inner ring and the outer ring; A wave reducer having

11. The wave reducer according to claim 10, The second oil-retaining member is a plurality of first recesses extending from a radially outer side toward a radially inner side; a plurality of second recesses extending from the radially inner side to the radially outer side; and The plurality of first recesses and the plurality of second recesses are arranged alternately in the circumferential direction.

12. The wave reducer according to any one of claims 9 to 11, a cylindrical third oil-retaining member disposed along the radially inner surface of the body portion; and A wave reducer in which an end face on one axial side of the third oil-retaining member is in axial contact with an end face on the other axial side of the flexible bearing.

13. The wave reducer according to claim 12, The third oil-retaining member is a plurality of outer protrusions protruding radially outward; a plurality of inner protrusions protruding radially inward; and The plurality of outer convex portions and the plurality of inner convex portions are arranged alternately in the circumferential direction.

14. The wave reducer according to claim 12 or 13, A wave reducer in which the first oil-retaining member and the third oil-retaining member are arranged in a position where they overlap in the radial direction in at least a portion of an axial region.

15. A wave reducer, Flexible gear and a wave generator rotatable about a central axis; a flexible bearing; an internal gear having a plurality of internal teeth arranged in a circumferential direction; a cylindrical third oil-retaining member; a housing to which the flexible gear is fixed; and The flexible gear is a flexible body portion extending in an axial direction around the central axis; a first oil-retaining member containing lubricating oil; and The body portion is a cylindrical first body portion extending in an axial direction; a cylindrical second body portion extending in the axial direction and disposed on one axial side of the first body portion; and the flexible bearing connects a radially outer surface of the wave generator and a radially inner surface of the second body portion so as to be rotatable relative to each other; the internal gear is disposed radially outward of the second body portion, the third oil-retaining member is disposed along a radially inner surface of the body portion, the housing is disposed on the other axial side of the flexible gear, a radially inner surface of the first oil-retaining member contacts a radially outer surface of the first body portion, the second body portion has a plurality of external teeth protruding radially outward from a radially outer surface, an end face on one axial side of the third oil-retaining member contacts an end face on the other axial side of the flexible bearing in the axial direction; A wave reducer in which the end face on the other axial side of the third oil-retaining member is in axial contact with the surface on one axial side of the housing.

16. A wave reducer, Flexible gear and a wave generator rotatable about a central axis; a flexible bearing; an internal gear having a plurality of internal teeth arranged in a circumferential direction; A roller bearing; and The flexible gear is a flexible body portion extending in an axial direction around the central axis; a first oil-retaining member containing lubricating oil; and The body portion is a cylindrical first body portion extending in an axial direction; a cylindrical second body portion extending in the axial direction and disposed on one axial side of the first body portion; and the flexible bearing connects a radially outer surface of the wave generator and a radially inner surface of the second body portion so as to be rotatable relative to each other; the internal gear is disposed radially outward of the second body portion, the roller bearing is disposed radially outward of the first body portion, a radially inner surface of the first oil-retaining member contacts a radially outer surface of the first body portion, the second body portion has a plurality of external teeth protruding radially outward from a radially outer surface, The outer ring of the roller bearing is fixed to the flexible gear, an inner ring of the roller bearing is fixed to the internal gear; the first oil-retaining member has a protruding portion protruding radially outward from a radially outer surface, A wave reducer in which a radially outer end of the protrusion is in radial contact with a radially inner surface of the inner ring of the roller bearing.

17. A wave reducer according to any one of claims 9 to 16; a motor that provides rotational power to the wave generator; an output portion rotatable with the flexible gear; A robot equipped with:

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