Wave gears and industrial robots

Abstract

The wave gear is provided with an internal toothing (3), an external toothing (5), and a shaft generator (6). The shaft generator (6) is provided with a cam (31) having a non-circular outer circumferential surface (31a) and a fourth bearing (32) arranged between the inner circumferential surface (21a) of the external toothing (5) and the outer circumferential surface (31a) of the cam (31). The fourth bearing (32) is provided with an outer ring (33), an inner ring (34), several balls (35), and a holder (36). A limiting section (37) is provided, which is in contact with the inner ring (34) in such a way as to prevent contact with the holder (36) and restricts the movement of the fourth bearing (32) in the direction of the axis of rotation (C). The restriction section (37) is formed such that the radial projection length from the outer circumferential surface (31a) of the cam (31) is uniform over the entire circumference of the outer circumferential surface (31a).

Description

TECHNICAL FIELD

[0001] The present invention relates to a wave gear and an industrial robot.

[0002] This application claims priority based on Patent Application No. 2022-075005 filed in Japan on April 28, 2022, and hereby cites the contents thereof. BACKGROUND TECHNOLOGY

[0003] A wave gear device includes internal gears, elastic external gears partially meshing with the internal gears, and a wave generator in contact with the inner peripheral surface of the external gears. The wave generator moves the meshing position of the internal gears and the external gears circumferentially around the rotation axis. The wave generator includes a cam having an elliptical outer peripheral surface with a major axis and a minor axis as viewed in the direction of the rotation axis, and a bearing disposed between the inner peripheral surface of the external gears and the outer peripheral surface of the cam.

[0004] A deep groove ball bearing, for example, is used as a bearing. Such a bearing has an elliptical shape, viewed in the direction of the rotation axis, which corresponds to the shape of the outer circumferential surface of the cam. The bearing comprises, for example, an outer ring, an inner ring, a rolling element arranged between the outer ring and the inner ring, and a retainer that holds the rolling element.

[0005] When driving the wave gear described above, a thrust force is generated by elastic deformation of the external gearing in the wave generator. If this thrust force causes the wave generator to move in the direction of the rotation axis, the internal and external gearing may no longer mesh properly. The load on the bearing may become excessive, and the bearings may be damaged. For example, if an attempt is made to restrict the movement of the cam in the direction of the rotation axis to prevent the wave generator from moving in the direction of the rotation axis, the bearing will move relative to the cam. Therefore, techniques are disclosed in which an adhesive is applied between the cam and the bearing to increase the bonding strength between the cam and the bearing. A technique is disclosed in which a flange is provided to restrict the retainer from popping out of the bearing when a thrust force is generated (see WO 2020 / 044524). OVERVIEW OF THE INVENTION OBJECT TO BE SOLVED BY THE INVENTION

[0006] However, in the above-described prior art, it is difficult to satisfy the bonding strength between the cam and the bearing due to the intrusion of oil, foreign matter, etc.

[0007] If a flange is provided that restricts the retainer from jumping out of the bearing, not only can lubrication of the bearing be hindered, but the retainer can be crushed and the bearing damaged.

[0008] For example, if a flange portion is formed in a circular shape as viewed in the direction of the rotation axis, the bearing will have an elliptical shape as viewed in the direction of the rotation axis. Therefore, the contact area of ​​the flange portion with the bearing is not uniform over the entire circumference. For example, on the minor axis side of the bearing, the flange portion will be in contact with the bearing inner ring. On the major axis side of the bearing, however, the flange portion may not be in contact with the bearing inner ring. This could cause the bearing inner ring to bend if the bearing inner ring is strongly pressed against the flange portion.

[0009] The present invention provides a wave gear and an industrial robot that can restrict the movement of the bearing in the direction of the rotation axis and prevent damage to the bearing. MEANS FOR SOLVING THE TASK

[0010] The wave gear according to one aspect of the present invention comprises an internal gear, an elastic external gear arranged radially inside the internal gear, and a wave generator in contact with the inner peripheral surface of the external gear, wherein the external gear partially engages with the internal gear and rotates relative to the internal gear about the rotation axis, the wave generator moves the engagement position of the internal gear and the external gear in the circumferential direction about the rotation axis, the wave generator comprises a cam with a non-circular outer peripheral surface and a bearing arranged between the inner peripheral surface of the external gear and the outer peripheral surface of the cam, wherein the bearing comprises an outer ring in contact with the inner peripheral surface of the external gear, an inner ring in contact with the outer peripheral surface of the cam, a plurality of rolling elements,which are arranged between the outer ring and the inner ring, and comprises a holder that holds the plurality of rolling elements, and comprises a restricting portion that is in contact with the inner ring of the bearing such that contact with the holder is avoided, wherein the restricting portion is formed such that the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of the outer peripheral surface of the cam, and the restricting portion restricts the movement of the bearing in the direction of the rotation axis.

[0011] This design allows the restricting portion to restrict the bearing's movement along the rotational axis while avoiding contact with the retainer. This restricts the bearing's movement along the rotational axis and prevents damage to the bearing retainer.

[0012] The restricting portion is formed such that the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of this outer peripheral surface. This ensures that the restricting portion is in uniform contact with the bearing inner ring over the entire circumference. Therefore, even if the bearing inner ring is strongly pressed against the restricting portion, it can be prevented from being bent and damaging the bearing.

[0013] In the above embodiment, the restricting portion is formed in the shape of a flange projecting radially outward from the outer peripheral surface of the cam, and the outer peripheral surface of the restricting portion may oppose the holder in the radial direction via a gap.

[0014] In the above configuration, the outer peripheral surface of the cam and the outer peripheral surface of the restricting portion may be formed in an elliptical shape or an oval shape having a major axis and a minor axis, respectively, as viewed in the direction of the rotation axis, wherein the major axis of the cam and the major axis of the restricting portion may be in the same line, and the minor axis of the cam and the minor axis of the restricting portion may be in the same line.

[0015] In the above embodiment, if the outer diameter of any part of the cam is defined as D1, the outer diameter of the same part of the restricting portion as the any part of the cam is defined as D2, and the radial thickness of the inner ring is defined as T, the outer diameter D1, D2 and the thickness T can satisfy (D2-D1) / 2≤T.

[0016] In the above configuration, the restricting portion may be provided on the both sides of the inner ring in the direction of the rotation axis.

[0017] In the above embodiment, the restricting portion may be formed integrally with the cam.

[0018] A wave gear according to another aspect of the present invention comprises an internal gear, an elastic external gear arranged radially inside the internal gear, and a wave generator in contact with the inner peripheral surface of the external gear, wherein the external gear partially engages with the internal gear and rotates relative to the internal gear about the rotation axis, the wave generator moves the engagement position of the internal gear and the external gear in the circumferential direction about the rotation axis, the wave generator comprises a cam having an outer peripheral surface, and a bearing arranged between the inner peripheral surface of the external gear and the outer peripheral surface of the cam, wherein the outer peripheral surface of the cam, viewed in the direction of the rotation axis, is formed either in an elliptical shape or an oval shape with a major and a minor axis, wherein the bearing has an outer ring,which is in contact with the inner peripheral surface of the external gear, an inner ring which is in contact with the outer peripheral surface of the cam, a plurality of rolling elements arranged between the outer ring and the inner ring, and a holder which holds the plurality of rolling elements, and a restricting portion formed in the shape of a flange which projects radially outward from the outer peripheral surface of the cam, wherein the restricting portion is formed to have an outer peripheral surface which, viewed in the direction of the rotation axis, is formed in either an elliptical shape or an oval shape with a major and a minor axis, the major axis of the cam and the major axis of the restricting portion lie on the same line, and the minor axis of the cam and the minor axis of the restricting portion lie on the same line,and the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of the outer peripheral surface of the cam, wherein the outer peripheral surface of the restricting portion faces the holder in the radial direction via a gap, and the restricting portion is in contact with the inner ring of the bearing and restricts the movement of the bearing in the direction of the rotation axis.

[0019] This design allows the restricting portion to avoid contact with the retainer and restrict the bearing's movement in the direction of the rotation axis, while maintaining a simple structure. Therefore, the bearing's movement in the direction of the rotation axis can be restricted and damage to the bearing retainer can be prevented.

[0020] The restricting portion can be easily formed such that the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of this outer peripheral surface. Therefore, the restricting portion is in uniform contact with the bearing inner ring over the entire circumference. Therefore, even if the bearing inner ring is strongly pressed against the restricting portion, the bearing inner ring can be prevented from being bent and the bearing damaged.

[0021] An industrial robot according to another aspect of the present invention comprises a driving force generating section that generates a rotational force, a wave gear having an input and an output, and a counterpart attached to the output of the wave gear, wherein the rotational force of the driving force generating section is input to the input, the output changes and outputs the rotational speed of the input, the wave gear includes internal gears, elastic external gears arranged radially inside the internal gears, and a wave generator in contact with the inner peripheral surface of the external gears, wherein the external gears partially mesh with the internal gears and rotate relative to the internal gears about the rotation axis and serve as one of the input and the output, the wave generator moves the engagement position of the internal gears and the external gears circumferentially around the rotation axis,The wave generator comprises a cam with a non-circular outer peripheral surface, and a bearing disposed between the inner peripheral surface of the external gear and the outer peripheral surface of the cam, the cam serving as the other of the input and output. The bearing comprises an outer ring in contact with the inner peripheral surface of the external gear, an inner ring in contact with the outer peripheral surface of the cam, a plurality of rolling elements disposed between the outer ring and the inner ring, and a retainer that retains the plurality of rolling elements. A restricting portion is formed such that the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of the outer peripheral surface of the cam.and restricts the movement of the bearing in the direction of the axis of rotation.

[0022] This design allows for the provision of an industrial robot that restricts the movement of the bearing in the direction of the rotation axis and prevents damage to the bearing. EFFECT OF THE INVENTION

[0023] The wave gear and industrial robot described above can limit the movement of the bearing in the direction of the rotation axis and prevent damage to the bearing. BRIEF EXPLANATION OF THE DRAWINGS

[0024] It shows: Fig. 1 is a schematic structural diagram of an industrial robot in an embodiment of the present invention; Fig. 2 is a sectional view along the rotational axis of a wave gear in an embodiment of the present invention; Fig. 3 is a top plan view of the cam in an embodiment of the present invention, corresponding to the sectional view along the line III-III of Fig. 2.; and Fig. 4 is a sectional view taken along the rotation axis showing a modified example of the restricting portion in an embodiment of the present invention. EMBODIMENT OF THE INVENTION

[0025] Next, the embodiment of the present invention will be explained with reference to the drawings. <industrieroboter>

[0026] Fig. 1 shows a schematic structural diagram of an industrial robot 100.

[0027] As in Fig. As shown in Figure 1, the industrial robot 100 is provided with a track rail 101, a base unit (an example of a counterpart in the claim) 102 freely movable on the track rail 101, and a robot body 103 provided on the base unit 102. Motors 106, 113a to 113f equipped with reduction gears are respectively provided in the joints 111, 112a to 112e of respective arms (an example of a counterpart in the claim) 115a to 115d of the base unit 102 or the robot body 103.

[0028] Each of the reduction gear-equipped motors 106, 113a to 113f has a similar configuration. Among the reduction gear-equipped motors 106, 113a to 113f, the reduction gear-equipped motor 106 provided in the base unit 102 will be explained as an example. This reduction gear-equipped motor 106 is provided with a wave gear 1 and an electric motor (an example of a motive power generating section in the claim) 110 that provides motive power to the wave gear 1.

[0029] In Fig. In Figure 1, further motors 113a to 113f with reduction gears are shown in a simplified manner, and the symbols for the wave gear and the electric motor are omitted. In the following explanation, only the motor 106 of the base unit 102 equipped with the reduction gear is explained, and the explanation of the further motors 113a to 113f equipped with reduction gears is omitted.

[0030] In the industrial robot 100, the robot body 103 runs on the guide rail 101, and each arm 115a to 115d takes different postures by driving each motor 106, 113a to 113f equipped with the reduction gear. <wellgetriebe>

[0031] Next, the wave gear 1 is tested using Fig. 2 to 3 explained.

[0032] Fig. 2 shows a sectional view of the wave gear 1 along the rotation axis C. In Fig. 2, the lower half of the drawing around the rotation axis C is omitted. In the following explanation, the direction of the rotation axis C is simply referred to as the axial direction, the direction around the rotation axis C is referred to as the circumferential direction, and the radial direction of the wave gear 1, which is orthogonal to the axial direction and the circumferential direction, is referred to as the radial direction. In the following explanation, the upper and lower directions in the state where the motor 106 equipped with the reduction gear is mounted on the base unit 102 are referred to as the upper and lower directions.

[0033] As in Fig. 2, the wave gear 1 is provided with a housing 2, an internal gear 3 and a first bearing 4 fixed to the housing 2, an external gear 5 provided radially inside the internal gear 3, a wave generator 6 provided radially inside the external gear 5, an output plate fixed to the external gear 5 together with the first bearing 4 (an example of the output in claim 7), and a reduction gear shaft 8 connected to a motor shaft 110a of an electric motor 110 and imparting a rotational force to the wave generator 6. The motor shaft 110a of the electric motor 110 is connected to the upper end (right side in Fig. 2) of the reduction gear shaft 8. At the lower end (left side in Fig. 2) the output plate 7 is arranged on the reduction gear shaft 8. <Gehäuse>

[0034] The housing 2 is fixed to the base unit 102 with a screw (not shown). The housing 2 is formed in the shape of a disc. However, the shape of the housing 2 is not limited to a disc shape. A cylindrical hub portion 2c is integrally formed in the radial center of the housing 2. The position of the motor 106 equipped with the reduction gear relative to the base unit 102 is determined by fitting this hub portion 2c into a through hole 102a formed, for example, in the base unit 102.

[0035] A stepped through hole 9 is formed in a large part of the radial center of the hub portion 2c. The reduction gear shaft 8 is inserted into the stepped through hole 9.

[0036] The stepped through-hole 9 has a small-diameter hole 9a formed in the upper part (on the side of the electric motor 110) and a large-diameter hole 9b formed in the lower part as the small-diameter hole 9a (on the side facing away from the electric motor 110). The large-diameter hole 9b is connected to the small-diameter hole 9a via a stepped portion 9c. The inner diameter of the large-diameter hole 9b is larger than that of the small-diameter hole 9a.

[0037] A sealing portion 10 is attached to the small-diameter bore 9a, which ensures sealing between the hub portion 2c and the reduction gear shaft 8. Various sealing elements, such as a rubber oil seal, can be used as the sealing portion 10.

[0038] A second bearing 11 is fitted into the large-diameter bore 9b. The second bearing 11 rotatably supports the upper end of the reduction gear shaft 8 on the hub portion 2c. For example, a deep groove ball bearing is used as the second bearing 11. However, it is not limited to this, and various bearings can be used. In the present embodiment, the second bearing 11 is axially positioned with respect to the hub portion 2c by abutting the outer ring 11a of the second bearing 11 against the stepped portion 9c of the stepped through-bore 9.

[0039] A gear receiving recess 12 is formed on the bottom surface 2a of the housing 2 in a large part of the radial center. The gear receiving recess 12 is open downwards and radially inwards. The internal gear 3 is received in the gear receiving recess 12. On the outer circumference of the bottom surface 12a of the gear receiving recess 12, a plurality of through holes 2b are formed, which pass through in the axial direction. The plurality of through holes 2b are arranged at equal intervals in the circumferential direction. The plurality of through holes 2b serve to fix the housing 2 together with the internal gear 3 and the first bearing 4 to the base unit 102. A screw (not shown) is inserted into each through hole 2b from above. <innenverzahnung>

[0040] The internal gearing 3 is formed in a circular ring by a rigid body. The axial center of the internal gearing 3 coincides with the rotation axis C. The outer peripheral surface of the internal gearing 3 is fitted into the inner peripheral surface of the gear receiving recess 12 of the housing 2. The top surface 3a of the internal gearing 3 abuts the bottom surface 12a of the gear receiving recess 12, thereby axially positioning the internal gearing 3 with respect to the housing 2. Through holes 3f are formed on the internal gearing 3 and extend in the axial direction. The through holes 3f are formed on the same axis as the through hole 2b of the housing 2. These through holes 3f each lead to corresponding through holes 2b in the housing 2.

[0041] An O-ring groove 3b is formed on the inner circumference of the upper surface 3a of the internal gear 3. An O-ring 13 is secured in the O-ring groove 3b. The O-ring 13 seals between the internal gear 3 and the housing 2.

[0042] An inner tooth 3c is formed circumferentially on the inner peripheral surface of the inner toothing 3. An outer tooth 5a of the outer toothing 5, described later, engages this inner tooth 3c.

[0043] A bearing receiving recess 14 is formed in a large part of the outer circumference of the bottom surface 3d of the internal gear 3. The bearing receiving recess 14 is open downwardly and radially outwardly. The first bearing 4 is received in the bearing receiving recess 14. An O-ring groove 3e is formed on the inner circumference of the bottom surface 14a of the bearing receiving recess 14. An O-ring 15 is secured in the O-ring groove 3e. The O-ring 15 seals between the internal gear 3 and the first bearing 4. <Erstes Lager>

[0044] The first bearing 4 is provided with an outer ring 16, an inner ring 17, and balls 18, which constitute a plurality of rolling elements arranged between the outer ring 16 and the inner ring 17. The inner peripheral surface of the inner ring 17 is fitted into the outer peripheral surface of the bearing receiving recess 14. The top surface 17a of the inner ring 17 abuts the bottom surface 14a of the bearing receiving recess 14, thereby axially positioning the first bearing 4 with respect to the internal gear 3.

[0045] Internal threads 17b are formed on the same axis on the top side 17a of the inner ring 17 as the through-hole 3f of the internal gearing 3. These internal threads 17b each lead to corresponding through-holes 3f of the internal gearing 3. A screw (not shown) inserted from above into each through-hole 2b of the housing 2 is screwed via the through-hole 3f of the internal gearing 3 to the internal thread 17b of the inner ring 17. As a result, the housing 2, the internal gearing 3, and the inner ring 17 of the first bearing 4 are integrally fixed to the base unit 102 by the screw (not shown).

[0046] On the outer circumference of the outer ring 16 of the first bearing 4, a plurality of axial through holes 16a are formed, extending in the axial direction. The plurality of through holes 16a are arranged at equal intervals in the circumferential direction. The plurality of through holes 16a serve to integrate the outer ring 16 of the first bearing 4, the external gear 5, and the output plate 7 by means of a screw (not shown).

[0047] A seal receiving recess 19 is formed on the inner circumference of the upper surface 16b of the outer ring 16. A seal portion 20 is provided in the seal receiving recess 19. The seal portion 20 seals between the outer ring 16 and the inner ring 17 on the upper side of the first bearing 4. Various sealing elements, such as a rubber oil seal, can be used as the seal portion 20.

[0048] The underside 16c of the outer ring 16 protrudes slightly deeper than the underside 17c of the inner ring 17. An O-ring groove 16d is formed on the inner circumference of the underside 16c of the outer ring 16. An O-ring 40 is secured in the O-ring groove 16d. The O-ring 40 seals between the outer ring 16 and the external gearing 5. <Außenverzahnung>

[0049] The external gear 5 is formed by an elastic member. For example, the external gear 5 is formed from a thin-walled metal plate. The external gear 5 has a cylindrical portion 21 concentric with the internal gear 3 and an outer flange portion 22 that bends and protrudes radially outward from the lower end of the cylindrical portion 21. The cylindrical portion 21 extends from the upper surface 3a of the internal gear 3 to the lower surface 16c of the outer ring 16 of the first bearing 4. The external tooth 5a is formed on the outer peripheral surface of the cylindrical portion 21. The external tooth 5a is formed at a position opposite the internal tooth 3c of the internal gear 3 in the radial direction. The external tooth 5a meshes with the internal tooth 3c of the internal gear 3. The number of teeth on the outer tooth 5a is less than the number of teeth on the inner tooth 3c. For example,the number of teeth of the outer tooth 5a is two less than the number of teeth of the inner tooth 3c.

[0050] The outer flange portion 22 extends from the lower end of the cylindrical portion 21 to the outer peripheral surface of the outer ring 16 of the first bearing 4. The outer periphery of the outer flange portion 22 overlaps the bottom surface 16c of the outer ring 16 in the axial direction. A thick-walled portion 22a is formed on the outer periphery of the outer flange portion 22, which is thicker than other parts of the outer flange portion 22. The thick-walled portion 22a is formed at a location where it overlaps the outer ring 16 in the axial direction. Through holes 22b are formed in the thick-walled portion 22a. The through holes 22b are formed on the same axis as the through holes 16a of the outer ring 16. These through holes 22b each lead to corresponding through holes 16a of the outer ring 16. <ausgangsplatte>

[0051] The output plate 7 is arranged such that it overlaps the thick-walled portion 22a of the outer flange portion 22 in the axial direction. The output plate 7 is formed in the shape of a disc. A pinion 107 is attached to the underside 7a of the output plate 7, which transmits the driving force, for example, of the motor 106 equipped with the reduction gear, to the base unit 102.

[0052] A cylindrical fitting portion 23 is formed on the outer periphery of the output plate 7, projecting toward the first bearing side 4. On the inner peripheral surface of the cylindrical fitting portion 23, the outer peripheral surface of the thick-walled portion 22a and a portion of the outer peripheral surface of the outer ring 16 of the first bearing 4 mesh with each other. This determines the relative positions of the housing 2, the internal gear 3, the first bearing 4, the external gear 5, and the output plate 7 in the radial and axial directions.

[0053] Through holes 7b are formed radially inside the cylindrical fitting portion 23 on the outer circumference of the output plate 7. The through holes 7b are formed on the same axis as the through holes 22b of the thick-walled portion 22a. These through holes 7b each lead to corresponding through holes 22b of the thick-walled portion 22a. In this configuration, for example, a screw (not shown) is inserted from the upper region of the outer ring 16 into the through hole 16a, the through hole 22b of the thick-walled portion 22a, and the through hole 7b of the output plate 7 in this order, and the screw is screwed into the internal thread (not shown) formed in the pinion 107. As a result, the outer ring 16 of the first bearing 4, the external gear 5, and the output plate 7 are integrally fixed to the pinion 107 by the screw (not shown).With the pinion 107 removed, the outer ring 16 of the first bearing 4, the external toothing 5 and the output plate 7 can be integrated, for example, by means of screws and nuts not shown.

[0054] An O-ring groove 7d is formed on the upper surface 7c of the output plate 7. The O-ring groove 7d extends radially inward from the through-hole 7b. An O-ring 25 is secured in the O-ring groove 7d. The O-ring 25 seals between the thick-walled portion 22a and the output plate 7.

[0055] A shaft insertion hole 24 is formed in the radial center of the output plate 7, extending axially. The reduction gear shaft 8 is inserted into the shaft insertion hole 24. An O-ring 25 is attached to the shaft insertion hole 24 of the output plate 7 to ensure sealing between the output plate 7 and the reduction gear shaft 8.

[0056] A cylindrical, upwardly projecting bearing hub 27 is integrally formed on the upper surface 7c of the output plate 7. The bearing hub 27 is formed radially outside the shaft insertion hole 24. The outer peripheral surface of a third bearing 28 is fitted on the inner peripheral surface of the bearing hub 27. The third bearing 28 rotatably supports the lower end of the reduction gear shaft 8 on the output plate 7. For the third bearing 28, a deep groove ball bearing, for example, is used. However, it is not limited to this, and various bearings can be used. <untersetzungsgetriebewelle>

[0057] The reduction gear shaft 8, whose two ends are rotatably supported by two bearings 11, 28, is formed hollow. The outer peripheral surface of the reduction gear shaft 8 is formed in a stepped shape. That is, the outer peripheral surface of the reduction gear shaft 8 includes an outer seal peripheral surface 8a formed at both ends, an outer bearing peripheral surface 8b formed radially inward of each outer seal peripheral surface 8a, and an outer shaft body peripheral surface 8c formed between the two outer bearing peripheral surfaces 8b.

[0058] Seals 10, 26 are mounted on each outer seal peripheral surface 8a. The second bearing 11 and the third bearing 28 are each mounted on each outer bearing peripheral surface 8b. The outer bearing peripheral surface 8b is formed such that its diameter is larger than the outer seal peripheral surface 8a across a step 8d. The outer shaft body peripheral surface 8c is formed such that its diameter is larger than the outer bearing peripheral surface 8b across a step 8e. Axial positioning of each bearing 11, 28 with respect to the reduction gear shaft 8 is achieved by each bearing 11, 28 abutting the corresponding step 8d, 8e. <wellengenerator>

[0059] The wave generator 6 is provided in the radial direction between the outer shaft body peripheral surface 8c of the reduction gear shaft 8 and the outer tooth 5a of the external gear 5 (inner tooth 3c of the internal gear 3). The wave generator 6 is provided with a cam 31 integrally formed on the outer shaft body peripheral surface 8c and a fourth bearing (an example of a bearing in the claim) 32 arranged between the outer peripheral surface 31a of the cam 31 and the inner peripheral surface 21a of the cylindrical portion 21 of the external gear 5. <nocken>

[0060] Fig. Figure 3 shows a top view of the cam 31, corresponding to the sectional view along the line III-III of Fig. 2.

[0061] As in Fig. 2 and Fig. As shown in Figure 3, the cam 31 is formed to extend radially outward from the outer peripheral surface 8c of the shaft body. The outer peripheral surface 31a of the cam 31 is formed in an elliptical shape when viewed in the axial direction. <Viertes Lager>

[0062] The fourth bearing 32 is, for example, a deep groove ball bearing. The fourth bearing 32 is provided with an outer ring 33, an inner ring 34, balls 35 constituting a plurality of rolling elements arranged between the outer ring 33 and the inner ring 34, and a retainer 36 that rollably holds the plurality of balls 35. The outer peripheral surface of the outer ring 33 is in contact with the inner peripheral surface 21a of the cylindrical portion 21 of the external gear 5. The inner peripheral surface of the inner ring 34 engages with the outer peripheral surface 31a of the cam 31. The axial length L1 of the inner ring 34 is shorter than the axial length L2 of the outer ring 33. The axial length L3 of the cam 31 approximately corresponds to the axial length L1 of the inner ring 34. <halter>

[0063] The holder 36 is a circular ring-shaped element that holds a plurality of balls 35 at equal intervals in the circumferential direction. The holder 36 has a gripping portion 36a that grips each of the balls 35 from the axial outside in a freely rolling manner, and a connecting portion (not shown) that connects adjacent gripping portions 36a to one another in the circumferential direction. The gripping portion 36a is located slightly lower than the axial lower end of the inner ring 34, viewed in the radial direction. <Einschränkungsabschnitt>

[0064] At the lower end of the cam 31, on the shaft body outer peripheral surface 8c of the shaft body, a restricting portion 37 is integrally formed. The restricting portion 37 is formed in a flange shape that protrudes radially outward from an outer peripheral surface 31a of the cam 31. An outer peripheral surface 37a of the restricting portion 37 is formed in an elliptical shape when viewed in the axial direction to match the shape of the outer peripheral surface 31a of the cam 31. The major axis RLa of the restricting portion 37 and the major axis CLa of the cam 31 are on the same line. The minor axis RSa of the restricting portion 37 and the minor axis CSa of the cam 31 are on the same line. The restricting portion 37 is therefore formed such that the radial protrusion length from the outer peripheral surface 31a of the cam 31 is uniform over the entire circumference of this outer peripheral surface 31a.

[0065] If the outer diameter of any part of the cam 31 is defined as D1, the outer diameter of the same part of the restricting portion 37 as any part of the cam 31 is defined as D2, and the wall thickness of the inner ring 34 of the fourth bearing 32 is defined as T, the outer diameter D1, D2 and the thickness T satisfy the equation: (D2−D1) / 2≤T

[0066] In addition to the above equation (1), the restricting portion 37 is integrally formed at the lower end of the cam 31 so as to face the retainer 36 (gripping portion 36a) of the fourth bearing 32 in the radial direction. Contact of the restricting portion 37 with the retainer 36 is reliably prevented.

[0067] The lower end of the inner ring 34 of the fourth bearing 32 abuts the upper surface 37b of the restricting portion 37. This restricts the axial movement of the fourth bearing 32.

[0068] The restricting portion 37 is formed such that the radial protrusion length from the outer peripheral surface 31a of the cam 31 is uniform over the entire circumference of the outer peripheral surface 31a. Therefore, the restricting portion 37 abuts evenly over the entire circumference of the inner ring 34 of the fourth bearing 32. The retainer 36 (gripping portion 36a) of the fourth bearing 32 and the restricting portion 37 are opposed in the radial direction across a certain gap G over the entire circumference of the outer peripheral surface 31a of the cam 31. The restricting portion 37 securely protrudes in the radial direction from the outer peripheral surface 31a of the cam 31. Therefore, the restricting portion 37 securely restricts the axial movement of the fourth bearing 32. <Funktionsweise des Wellgetriebes>

[0069] Next, the operation of the wave gear 1 of the reduction gear-equipped motor 106 will be explained. The operation of the wave gear of the other reduction gear-equipped motors 113a to 113f in the robot body 103 is similar to that of the wave gear 1 of the reduction gear-equipped motor 106 in the base unit 102.

[0070] First, the outer peripheral surface 31a of the cam 31 of the wave generator 6 is elliptically shaped when viewed in the axial direction. Therefore, the external gear 5 is elastically deformed via the fourth bearing 32, and the external tooth 5a and the internal tooth 3c of the internal gear 3 are partially engaged. In this state, when the motor shaft 110a is rotated by the drive of the electric motor 110, the reduction gear shaft 8 is rotated integrally with this motor shaft 110a. The cam 31 is rotated integrally with the reduction gear shaft 8. That is, the cam 31 of the wave generator 6 serves as an input to which the rotational force of the motor shaft 110a of the electric motor 110 is input.

[0071] The external tooth 5a and the internal tooth 3c rotate relative to each other around the rotation axis C due to the different number of teeth between them, while their meshing positions move in the circumferential direction because they have a different number of teeth. In the present embodiment, the number of teeth of the external tooth 5a is less than the number of teeth of the internal tooth 3c. Therefore, the external tooth 5 rotates at a lower rotation speed than the reduction gear shaft 8. The external tooth 5 rotates with elastic deformation.

[0072] The outer flange portion 22 of the external gear 5 is integrated with the outer ring 16 of the first bearing 4 and the output plate 7. Therefore, this outer ring 16 of the first bearing 4 and the output plate 7 are output at a reduced speed with respect to the rotation of the motor shaft 110a (reduction gear shaft 8). That is, the external gear 5 serves as an output, outputting the rotation of the cam 31, which is the input, at a changed speed (in the case of the present embodiment, at a reduced speed).

[0073] By rotating the output plate 7, the pinion 107 is rotated. The base unit 102 is then moved along the guide rail 101 (see Fig. 1).

[0074] When the wave gear 1 is driven, a downward thrust force is generated in the wave generator 6 due to the elastic deformation of the external gearing 5. The cam 31 of the wave generator 6 is formed integrally with the reduction gear shaft 8. The reduction gear shaft 8 is restricted in its axial movement by the second bearing 11 and the third bearing 28, which are arranged on both axial sides. Therefore, a downward thrust force acts on the fourth bearing 32 of the wave generator 6.

[0075] On the outer shaft body peripheral surface 8c of the reduction gear shaft 8, the restricting portion 37 is integrally formed at the lower end of the cam 31. The restricting portion 37 is formed in a flange shape that protrudes radially outside the outer peripheral surface 31a of the cam 31. The lower end of the inner ring 34 of the fourth bearing 32 abuts against the restricting portion 37. Therefore, the movement of the fourth bearing 32 in the axial direction is restricted by the restricting portion 37.

[0076] In this way, in the above-described strain wave gear 1, the movement of the fourth bearing 32 in the axial direction can be restricted by the restricting portion 37. Therefore, the inner tooth 3c of the inner gear 3 and the outer tooth 5a of the outer gear 5 can mesh continuously and correctly. Thus, the strain wave gear 1 can operate stably.

[0077] The restricting portion 37 is formed such that contact with the retainer 36 of the fourth bearing 32 is avoided. Therefore, damage to the fourth bearing 32 by the restricting portion 37 can be prevented. In addition, the restricting portion 37 is formed such that the radial protrusion length from the outer peripheral surface 31a of the cam 31 is uniform over the entire circumference of the outer peripheral surface 31a. Therefore, the top surface 37b of the restricting portion 37 abuts evenly over the entire circumference of the inner ring 34 of the fourth bearing 32. Consequently, even if the inner ring 34 of the fourth bearing 32 is strongly pressed against the restricting portion 37, the inner ring 34 is not subjected to local stress. As a result, the inner ring 34 can be prevented from being bent and the fourth bearing 32 from being damaged.

[0078] The restricting portion 37 faces the retainer 36 (gripping portion 36a) across a gap G in the radial direction, thereby avoiding contact with the retainer 36 of the fourth bearing 32. This configuration can simplify the structure of the restricting portion 37 and avoid contact with the retainer 36.

[0079] The outer peripheral surface 31a of the cam 31 and the outer peripheral surface 37a of the restricting portion 37 are each formed in an elliptical shape when viewed in the axial direction. The major axis RLa of the restricting portion 37 and the major axis CLa of the cam 31 are on the same line. The minor axis RSa of the restricting portion 37 and the minor axis CSa of the cam 31 are on the same line. Therefore, it can be ensured that the radial protrusion length of the restricting portion 37 from the outer peripheral surface 31a of the cam 31 is uniform over the entire circumference of the outer peripheral surface 31a.

[0080] The outer diameter D1 of any part of the cam 31, the outer diameter D2 of the same part of the restricting portion 37 as any part of the cam 31, and the wall thickness T of the inner ring 34 of the fourth bearing 32 satisfy the above equation (1). Therefore, contact of the restricting portion 37 with the retainer 36 can be more reliably avoided, and the axial movement of the fourth bearing 32 can be more reliably restricted.

[0081] The restricting portion 37 is integrally formed on the outer peripheral surface 8c of the shaft body and the lower end of the cam 31. Therefore, the restricting portion 37 can be easily provided.

[0082] The motors 106, 113a to 113f equipped with reduction gears using the above-described wave generator 6 are used for the industrial robot 100. This can prevent damage to the fourth bearing 32 and provide a highly reliable industrial robot 100 with stable operation.

[0083] The present invention is not limited to the above-described embodiment and includes various modifications of the above-described embodiment as long as they do not deviate from the purpose of the invention.

[0084] For example, the above embodiment explained a case where the reduction-gear-equipped motors 106, 113a to 113f provided with the wave gear unit 1 are used for the industrial robot 100. However, this is not limited to this, and the wave gear unit 1 can be used to drive various industrial robots other than the industrial robot 100. Examples of industrial robots include electric wheelchairs, driving devices, and various processing machines such as multi-tasking machines. The wave gear unit 1 can be used, for example, in the drive (driving unit) of an electric wheelchair, a driving device, and a processing machine.

[0085] The above-described embodiment explained the case where an electric motor 110 is used as the driving force generating section, which generates a rotational force on the cam 31 as an input. However, this is not limited to this, and any device that generates a rotational force on the cam 31 as the driving force generating section is acceptable. For example, a hydraulic motor, a motor, etc., can be used instead of the electric motor 110.

[0086] The above-described embodiment explained the case where the fourth bearing 32 is, for example, a deep groove ball bearing. However, it is not limited to this, and any bearing with an outer ring, an inner ring, a rolling element, and a retainer is acceptable. The rolling element does not have to be a ball 35. For example, cylindrical rollers can also be used as rolling elements instead of balls 35.

[0087] The above-described embodiment explained the case where the cam 31 of the wave generator 6 serves as an input to which the rotational force of the motor shaft 110a of the electric motor 110 is input. A case where the external gear 5 serves as an output, outputting the rotation of the cam 31 at a changed speed, was explained. However, this is not limited to this, and it is possible for the external gear 5 to serve as the input and the cam 31 (reduction gear shaft 8) to serve as the output.

[0088] The above-described embodiment explained the case where the outer peripheral surface 31a of the cam 31 is formed in an elliptical shape when viewed in the axial direction. The case where the outer peripheral surface 37a of the restricting portion 37 is formed in an elliptical shape when viewed in the axial direction was explained to match the shape of the outer peripheral surface 31a of the cam 31. However, this is not limited to this, and it is acceptable if the outer peripheral surface 31a of the cam 31 and the outer peripheral surface 37a of the restricting portion 37 are not circular. For example, the outer peripheral surface 31a of the cam 31 and the outer peripheral surface 37a of the restricting portion 37 may have a polygonal shape when viewed in the axial direction.It is acceptable if the restricting portion 37 is formed such that the radial projection length from the outer peripheral surface 31a of the cam 31 is uniform over the entire circumference of this outer peripheral surface 31a. Preferably, the outer peripheral surface 31a of the cam 31 should be elliptical or oval, viewed in the axial direction, with major and minor axes.

[0089] The above-described embodiment explained the case where the O-ring 13 is provided for sealing between the internal gear 3 and the housing 2. The case where the O-ring 15 is provided for sealing between the internal gear 3 and the first bearing 4 was explained. The case where the O-ring 25 is provided for sealing between the thick-walled portion 22a and the output plate 7 was explained. The case where the O-ring 40 is provided for sealing between the outer ring 16 and the external gear 5 was explained. However, this is not limited to this, and various sealing members can be used instead of the O-rings 13, 15, 25, and 40.

[0090] The above-described embodiment explained the case where the wave gear 1 is provided with the housing 2. However, this is not limited to this, and the housing 2 may not be provided. For example, the internal gear 3 may be directly fixed to the base unit 102, etc., or the reduction gear shaft 8 may be directly rotatably supported on the base unit 102, etc.

[0091] The above-described embodiment explained the case where the wave gear 1 is provided with the output plate 7. The case where the rotation of the motor shaft 110a (reduction gear shaft 8) is output via this output plate 7 was explained. However, this is not limited to this, and the rotation of the motor shaft 110a (reduction gear shaft 8) can also be output directly from the external gear 5.

[0092] The above-described embodiment explained the case where the housing 2, the internal gear 3, and the inner ring 17 of the first bearing 4 are integrally fixed to the base unit 102 by bolts (not shown). However, this is not limited to this, and various methods can be used to fix the internal gear 3 and the inner ring 17 of the first bearing 4. For example, the internal gear 3 and the inner ring 17 of the first bearing 4 may be fixed in advance. The housing 2, the internal gear 3, and the inner ring 17 of the first bearing 4 may be fixed in advance and fixed to a counterpart (e.g., the base unit 102).

[0093] The above-described embodiment explained the case where the reduction gear shaft 8 is hollow. However, this is not limited to this, and the reduction gear shaft 8 may also be solid. For example, the reduction gear shaft 8 may be provided with spur gears, and the rotation of the motor shaft 110a may be transmitted to the reduction gear shaft 8 via these spur gears.

[0094] The above-described embodiment explained the case where the restricting portion 37 is integrally formed at the lower end of the cam 31. The case where the lower end of the inner ring 34 of the fourth bearing 32 abuts against the upper surface 37b of the restricting portion 37 was explained. However, this is not limited to this, and it is also possible to provide the restricting portion 37 on both sides in the axial direction of the inner ring 34. With this configuration, the movement of the fourth bearing 32 in the axial direction can be securely restricted regardless of the direction of the thrust force acting on the fourth bearing 32. The restricting portion 37 may be a separate body instead of being integrally formed with the reduction gear shaft 8 or the cam 31. For example, the restricting portion 37 may be configured as follows. (Modified example of the restriction section)

[0095] Fig. 4 shows a sectional view along the rotation axis C showing a modified example of the restricting portion 37. Fig. 4 corresponds to the above Fig. 2.

[0096] As in Fig. As shown in FIG. 4, the restricting portion 37 may be provided with a restricting support 41 extending from the upper end of the bearing hub 27 toward the fourth bearing 32, and a restricting portion body 42 provided on the restricting support 41. The restricting portion body 42 is fixed to the restricting support 41 by unillustrated bolts or welding, etc.

[0097] The restricting portion body 42 extends from the restricting support 41 along the axial direction and is formed such that the front end 42a abuts against the inner ring 34 of the fourth bearing 32. That is, the restricting portion body 42 is provided so as to avoid contact with the retainer 36 of the fourth bearing 32. The restricting portion body 42 restricts the axial movement of the fourth bearing 32. The restricting portion body 42 is formed such that the radial projection length from the outer peripheral surface 31a of the cam 31 is uniform over the entire circumference of this outer peripheral surface 31a. In this configuration, the same effects as in the aforementioned embodiment can be achieved.

[0098] The embodiments disclosed in the present description that consist of multiple objects may be integrated with the multiple objects, or conversely, those consisting of a single object may be divided into multiple objects. Regardless of whether they are integrated or not, it is sufficient if they are designed to fulfill the purpose of the invention. EXPLANATION OF REFERENCE SYMBOLS

[0099] 1... wave gear, 3... internal gear, 5... external gear, 6... wave generator, 21... cylindrical section, 21a... inner peripheral surface, 31... cam, 31a... outer peripheral surface, 32... fourth bearing (bearing), 33... outer ring, 34... inner ring, 35... ball (rolling element), 36... retainer, 37... restricting section, 37a... outer peripheral surface, 42... restricting section body (restricting section), 100... industrial robot, 107... pinion (counterpart), 115a, 115b, 115c, 115d... arm (counterpart), C... rotation axis, CLa... major axis of the cam, CSa... minor axis of the cam, D1... any outer diameter of the cam, D2... outer diameter on D1 in the restricting section, G... gap, RLa... major axis of the restriction section, RSa... minor axis of the restriction section QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-075005

[0002] WO 2020 / 044524

[0005] < / halter> < / nocken> < / wellengenerator> < / untersetzungsgetriebewelle> < / ausgangsplatte> < / innenverzahnung> < / wellgetriebe> < / industrieroboter>

Claims

[1] Wave gear, comprising: an internal gear, an elastic external toothing arranged radially inside the internal toothing, and a wave generator which is in contact with the inner peripheral surface of the external gear, wherein the external toothing partially engages the internal toothing and rotates relative to the internal toothing about the axis of rotation, the wave generator moves the meshing position of the internal gearing and the external gearing in the circumferential direction around the rotation axis, the wave generator includes: a cam having a non-circular outer peripheral surface and a bearing arranged between the inner peripheral surface of the external gear and the outer peripheral surface of the cam, where the warehouse includes: an outer ring which is in contact with the inner peripheral surface of the external toothing, an inner ring which is in contact with the outer peripheral surface of the cam, a plurality of rolling elements arranged between the outer ring and the inner ring, and a holder that holds the plurality of rolling elements, and comprises a restricting portion which is in contact with the inner ring of the bearing in such a way as to avoid contact with the holder, wherein the restricting portion is formed such that the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of the outer peripheral surface of the cam, and the restricting section restricts the movement of the bearing in the direction of the rotation axis. [2] A wave gear according to claim 1, wherein the restricting portion is formed in the shape of a flange projecting radially outward from the outer peripheral surface of the cam, and the outer peripheral surface of the restricting portion is opposed to the holder in the radial direction via a gap. [3] Wave gear according to claim 2, wherein the outer peripheral surface of the cam and the outer peripheral surface of the restricting portion, each viewed in the direction of the rotation axis, are formed in an elliptical shape or an oval shape having a major and a minor axis, wherein the major axis of the cam and the major axis of the restricting portion are in the same line, and the minor axis of the cam and the minor axis of the restricting portion are in the same line. [4] Wave gear according to one of claims 1 to 3, wherein, if the outer diameter of any part of the cam is defined as D1, the outer diameter of the same part of the restriction portion as the arbitrary part of the cam is defined as D2, and the radial thickness of the inner ring is defined as T, the outer diameter D1, D2 and the thickness T (D2-D1) / 2≤T. [5] A wave gear according to any one of claims 1 to 3, wherein the restricting portion is provided on both sides of the inner ring in the direction of the rotation axis. [6] A wave gear according to any one of claims 1 to 3, wherein the restricting portion is formed integrally with the cam. [7] Wave gear, comprising: an internal gear, an elastic external toothing arranged radially inside the internal toothing, and a wave generator which is in contact with the inner peripheral surface of the external gear, wherein the external toothing partially engages the internal toothing and rotates relative to the internal toothing about the axis of rotation, the wave generator moves the meshing position of the internal gearing and the external gearing in the circumferential direction around the rotation axis, the wave generator includes: a cam having an outer peripheral surface, and a bearing arranged between the inner peripheral surface of the external gear and the outer peripheral surface of the cam, wherein the outer peripheral surface of the cam, viewed in the direction of the rotation axis, is formed either in an elliptical shape or an oval shape with a major and a minor axis, where the warehouse includes: an outer ring which is in contact with the inner peripheral surface of the external toothing, an inner ring which is in contact with the outer peripheral surface of the cam, a plurality of rolling elements arranged between the outer ring and the inner ring, and a holder that holds the plurality of rolling elements, and a restricting portion formed in the shape of a flange projecting radially outward from the outer peripheral surface of the cam, wherein the restriction portion is formed such that it has an outer peripheral surface which, viewed in the direction of the axis of rotation, is formed either in an elliptical shape or an oval shape with a major and a minor axis, the major axis of the cam and the major axis of the restriction section lie in the same line and the minor axis of the cam and the minor axis of the restriction section lie in the same line, and the radial projection length from the outer peripheral surface of the cam is uniform over the entire circumference of the outer peripheral surface of the cam, wherein the outer peripheral surface of the restriction portion is opposite to the holder in the radial direction via a gap, and the restricting portion is in contact with the inner ring of the bearing and restricts the movement of the bearing in the direction of the axis of rotation. [8] Industrial robots, including: a driving force generating section that generates a rotational force, a wave gear having an input and an output, and a counterpart attached to the output of the wave gear, wherein the rotational force of the motive force generating section is input into the input, the output changes the speed of rotation of the input and outputs, The wave gear includes: an internal gear, an elastic external toothing arranged radially inside the internal toothing, and a wave generator which is in contact with the inner peripheral surface of the external gear, wherein the external toothing partially engages the internal toothing and rotates relative to the internal toothing about the axis of rotation and serves as one of the input and output, the wave generator moves the meshing position of the internal gearing and the external gearing in the circumferential direction around the rotation axis, the wave generator includes: a cam having a non-circular outer peripheral surface, and a bearing arranged between the inner peripheral surface of the external gear and the outer peripheral surface of the cam, where the cam serves as the other of the input and the output, the warehouse includes: an outer ring which is in contact with the inner peripheral surface of the external toothing, an inner ring which is in contact with the outer peripheral surface of the cam, a plurality of rolling elements arranged between the outer ring and the inner ring, and a holder that holds the plurality of rolling elements, and comprises a restricting portion which is in contact with the inner ring of the bearing in such a way as to avoid contact with the holder, wherein the restricting portion is formed such that the radial protrusion length from the outer peripheral surface of the cam is uniform over the entire circumference of the outer peripheral surface of the cam, and restricts the movement of the bearing in the direction of the rotation axis.

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