Transmission device

Abstract

To provide a transmitter capable of securing rigidity of a ring gear.SOLUTION: A transmitter 100 comprises: a ring gear 42 having a first gear 41, an outer peripheral surface provided with external teeth 422 that mesh with the first gear 41, and an inner peripheral surface provided with internal teeth 424; a second gear 50 meshing with the internal teeth 424 of the ring gear 42; and thrust bearing means 45 arranged on the inner tooth 424 side with respect to the axis of the second gear 50 and receiving a thrust load.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transmission device. [Background technology]

[0002] There is known a transmission device that reduces the speed of rotation inputted through a ring gear and outputs the reduced speed. For example, Patent Document 1 describes a transmission device that reduces the speed of rotation inputted through a ring gear having external teeth and internal teeth and outputs the reduced speed. This transmission device includes a ring gear having external teeth and internal teeth that mesh with a first gear connected to a drive source, a second gear that meshes with the internal teeth of the ring gear, and a reduction unit that reduces the speed of the inputted from the second gear. This ring gear is rotatably supported by a bearing disposed radially inward of the internal teeth. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-158143 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have studied a transmission device that transmits rotation via a ring gear and have come to the following realization. From the viewpoint of ensuring rotational accuracy, it is desirable for a ring gear having external and internal teeth to have sufficient rigidity against a load input to the external teeth. However, in the transmission device described in Patent Document 1, the ring gear is supported by a bearing located inside the internal gear, making it difficult to ensure the rigidity of the ring gear.

[0005] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a transmission device capable of ensuring the rigidity of the ring gear. [Means for solving the problem]

[0006] In order to solve the above problems, a transmission device of one embodiment of the present invention comprises a first gear, a ring gear having an outer peripheral surface provided with external teeth that mesh with the first gear and an inner peripheral surface provided with internal teeth, a second gear that meshes with the internal teeth of the ring gear, and thrust bearing means that is positioned on the inner teeth side of the axis of the second gear and receives thrust loads.

[0007] Any combination of the above components, or mutual substitution of the components or expressions of the present invention between methods, systems, etc. are also valid aspects of the present invention. Effect of the Invention

[0008] According to the present invention, a transmission device capable of ensuring the rigidity of the ring gear can be provided. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side cross-sectional view that shows a schematic diagram of a transmission device according to a first embodiment. [Diagram 2] FIG. 11 is a side cross-sectional view that shows a schematic diagram of a transmission device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below based on preferred embodiments with reference to the drawings. In the embodiments and modified examples, the same or equivalent components and members are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The dimensions of the members in each drawing are enlarged or reduced as appropriate for ease of understanding. Some of the members that are not important for explaining the embodiments are omitted in each drawing.

[0011] In addition, although terms including ordinal numbers such as first, second, etc. are used to describe various components, these terms are used only for the purpose of distinguishing one component from another component, and the components are not limited by these terms.

[0012] [First embodiment] Hereinafter, the configuration of a transmission device 100 according to a first embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a side cross-sectional view that shows a schematic diagram of the transmission device 100 according to the present embodiment. The transmission device 100 of this example can be applied to rotate, for example, the wrist or turntable of an industrial robot. The transmission device 100 reduces the speed of rotation input from a driving source 6 and transmits it to a counterpart device (not shown) that is to be driven. The transmission device 100 has a gear unit 4 that transmits the rotation from the driving source 6, and a reduction section 10.

[0013] 1, the direction along the central axis La of the internal gear 16 of the reduction gear unit 10, which will be described later, is referred to as the "axial direction," and the circumferential direction and radial direction of a circle centered on the central axis La are referred to as the "circumferential direction" and the "radial direction," respectively. For convenience, one side in the axial direction (the right side in the figure) will be referred to as the input side, and the other side (the left side in the figure) will be referred to as the anti-input side.

[0014] (Gear unit) The gear unit 4 will be described with reference to FIG. 1. The gear unit 4 includes a first gear 41, a ring gear 42, a connecting member 44, bearing means 45, 46, and casings 22, 23. The casings 22, 23 function as an outer shell that houses the gear unit 4, particularly the ring gear 42. The casings 22, 23 include a first casing 22, a disk-shaped second casing 23 that closes the input side of the first casing 22, and a third casing 16. An outer periphery 232 of the second casing 23 is connected to an input side end 222 of the first casing 22 by a connecting means such as a bolt B2. The second casing 23 functions as a base that supports the bearing means 45, 46.

[0015] The first gear is connected to an output shaft 62 of a driving source 6, and a rotational driving force is input to the first gear 41 from the driving source 6. The driving source 6 is, for example, a motor.

[0016] The ring gear 42 has an outer peripheral surface provided with external teeth 422 that mesh with the first gear 41, and an inner peripheral surface provided with internal teeth 424. A plate-shaped intermediate portion 426 is provided radially inward of the external teeth 422, and the internal teeth 424 are provided inside the intermediate portion 426. The intermediate portion 426 has a plurality of through holes 427 drilled in the axial direction at positions offset from the radial center.

[0017] In this example, the ring gear 42 is a hollow annular member having an outer peripheral surface and an inner peripheral surface as a whole, and is formed with an inner peripheral step portion 425 on its inner peripheral side to which the connecting member 44 is connected. The ring gear 42 is supported by bearing means 45, 46 via the connecting member 44 so as to be rotatable about the central axis La.

[0018] There is no limitation on the configuration of the first gear 41 and the external teeth 422, but in this example, the first gear 41 and the external teeth 422 are bevel gears. The internal teeth 424 mesh with the second gear 50 of the reduction gear unit 10, and transmit the rotation of the ring gear 42 to the reduction gear unit 10 via the second gear 50. There is no limitation on the configuration of the internal teeth 424 and the second gear 50, but in this example, the internal teeth 424 and the second gear 50 are spur gears. For example, they may be helical gears.

[0019] In this embodiment, three second gears 50 are disposed at 120° intervals in the circumferential direction at positions offset from the central axis La. The shaft centers Lb (centers of rotation) of the three second gears 50 extend in the axial direction.

[0020] The bearing means 45, 46 include thrust bearing means 45 for receiving the thrust load of the ring gear 42, and radial bearing means 46 for receiving the radial load of the ring gear 42. There is no limitation on the configuration of the thrust bearing means 45. In this example, the thrust bearing means 45 has a first raceway 453 and a second raceway 454 that face each other in the axial direction (thrust direction) with a plurality of rolling elements 452 in between. In this example, the plurality of rolling elements 452 are cylindrical bodies (rollers) and are arranged at predetermined intervals in the circumferential direction. The positions of the plurality of rolling elements 452 are restricted within a predetermined range by a retainer (not shown). The first raceway 453 and the second raceway 454 are hollow disk-shaped members.

[0021] In this example, the thrust bearing means 45 overlaps with the radial bearing means 46 when viewed from the radial direction. In this case, the thickness in the axial direction can be reduced compared to a configuration in which they do not overlap when viewed from the radial direction. The thrust bearing means 45 is disposed at a position radially separated from the radial bearing means 46. The axial range of the thrust bearing means 45 overlaps partially or entirely with the axial range of the radial bearing means 46.

[0022] The thrust bearing means 45 is disposed on the side of the axis Lb of the second gear 50 where the internal teeth 424 are provided. In particular, the thrust bearing means 45 is disposed radially outward from the axis Lb. In the example of FIG. 1, at least a portion of the thrust bearing means 45 is disposed radially outward from the internal teeth 424. More specifically, the entire thrust bearing means 45 is disposed radially outward from the internal teeth 424. In this case, by disposing the thrust bearing means 45 radially outward, the thrust rigidity of the ring gear 42 can be increased. By increasing the thrust rigidity, the deflection of the ring gear 42 is reduced, and the deterioration of the rotational accuracy caused by the deflection can be suppressed. In addition, under the condition of constant rigidity, the ring gear 42 can be made thinner, which is advantageous for weight reduction.

[0023] The connection member 44 is a hollow disk-shaped member connected to the inner periphery side of the ring gear 42. The connection member 44 has an outer periphery fitting portion 442 that fits into an inner periphery step portion 425 of the ring gear 42, and an inner periphery fitting portion 444 that is fixed to the radial bearing means 46. The connection member 44 has a plurality of female threads 445 drilled in the axial direction at a position offset from the radial center. The plurality of female threads 445 are provided at positions overlapping with the plurality of through holes 427 of the ring gear 42 as viewed from the axial direction, at a predetermined interval in the circumferential direction. The connection member 44 is fixed to the ring gear 42 by screwing the bolt B3 that passes through the through hole 427 into the female thread 445. In this example, the neck of the bolt B3 engages with a seat that is provided in a stepped shape around the inner periphery surface of the through hole 427. In this example, the inner periphery fitting portion 444 is an inner cylindrical surface of the hollow portion of the connection member 44, and has a shape that allows the radial bearing means 46 to fit therein.

[0024] As shown in FIG. 1, the thrust bearing means 45 overlaps with the external teeth 422 when viewed from the axial direction. In this case, the axial position of the external teeth 422 is stable, so that noise and accuracy degradation due to bending of the ring gear 42 can be suppressed. The first race 453 is axially connected to the second casing 23. In this case, the number of parts is reduced, which is advantageous for thinning. Specifically, the first race 453 of the thrust bearing means 45 is fixed in a state of being fitted to the radial inner side of the peripheral step 233 formed on the opposite input side of the second casing 23. The second race 454 of the thrust bearing means 45 is fixed in a state of being fitted to the radial outer side of the peripheral step 423 formed on the input side of the ring gear 42. In this example, the ring gear 42 is directly connected to the second race 454. In this case, the number of parts is reduced, which is advantageous for thinning. The thrust bearing means 45 is at least partially surrounded by a peripheral wall portion 235 formed on the anti-input side of the second casing 23.

[0025] There is no limitation on the configuration of the radial bearing means 46. In this example, the radial bearing means 46 is a deep groove ball bearing having a rolling element 462, an inner ring 463, and an outer ring 464. The inner ring 463 is fitted and fixed to the outer peripheral surface of a hollow inner cylindrical portion 236 protruding toward the non-input side of the second casing 23. In this example, the input side of the inner ring 463 is positioned by abutting against a stepped seat provided around the outer peripheral surface of the inner cylindrical portion 236, and the non-input side of the inner ring 463 is restricted from moving in the axial direction by abutting against a stop ring 237 fitted and fixed to the outer peripheral surface of the inner cylindrical portion 236.

[0026] In this example, the input side of the outer ring 464 is positioned by abutting against a stepped seat provided around the inner surface of the inner fitting portion 444 of the connecting member 44, and the non-input side of the outer ring 464 is restricted in axial movement by abutting against a retaining ring 238 which is fitted and fixed to the inner surface of the inner fitting portion 444.

[0027] (Deceleration part) Next, the speed reducer 10 will be described with reference to Figures 1 and 2. The speed reducer 10 of this embodiment is a so-called distribution-type eccentric oscillating gear mechanism in which the crankshaft (eccentric body shaft) is positioned offset from the axis of the internal gear. The speed reducer 10 is configured to rotate one of the internal gear and the external gear by oscillating the external gear that meshes with the internal gear, and to output the generated rotation component from an output member to a driven device.

[0028] The speed reducer portion 10 mainly includes an eccentric body shaft 12, an external gear 14, a third casing 16 (internal gear 16), carriers 18, 20, a first casing 22, main bearings 24, 26, a center pipe 52, and a second gear 50.

[0029] The carriers 18, 20 include a first carrier 18 arranged on the side opposite to the input side of the external gear 14, and a second carrier 20 arranged on the side opposite to the input side of the external gear 14. The main bearings 24, 26 include a first main bearing 24 arranged on the side opposite to the input side of the external gear 14, and a second main bearing 26 arranged on the side opposite to the input side of the external gear 14. In this example, the main bearings 24, 26 are tapered roller bearings. The third casing 16 (internal gear 16) is hollow and cylindrical, and has a recess 224 that accommodates the outer ring of the first main bearing 24 and a recess 226 that accommodates the outer ring of the second main bearing 26. The carriers 18, 20 are rotatably supported by the third casing 16 (internal gear 16) via the first main bearing 24 and the second main bearing 26. The carriers 18, 20 are hollow and disk-like or cylindrical as a whole. The carriers 18, 20 rotatably support the eccentric shaft 12 via an eccentric shaft bearing 34.

[0030] The carriers 18, 20 have central holes 183, 203 formed at their radial centers. The central holes 183, 203 are generally circular and pass through in the axial direction. The carriers 18, 20 have eccentric body shaft holes 182, 202 to accommodate the eccentric body shaft bearings 34. The eccentric body shaft holes 182, 202 are generally circular and pass through in the axial direction. The carrier 18 has three eccentric body shaft holes 182 arranged at positions offset from the radial center. The three eccentric body shaft holes 182 are arranged at equal intervals of 120° in the circumferential direction. The carrier 20 has three eccentric body shaft holes 202 arranged at positions offset from the radial center. The three eccentric body shaft holes 202 are arranged at equal intervals of 120° in the circumferential direction.

[0031] (Eccentric shaft) Three eccentric body shafts 12 are disposed at positions offset from the central axis La of the internal gear 16. The three eccentric body shafts 12 are disposed at equal intervals of 120° in the circumferential direction. Only one eccentric body shaft 12 is shown in FIG. 1. The eccentric body shaft 12 has a plurality of eccentric portions 122 for oscillating the external gear 14. The axis of the eccentric portion 122 is eccentric with respect to the rotation center line of the eccentric body shaft 12. In this embodiment, two eccentric portions 122 are provided, and the eccentric phases of adjacent eccentric portions 122 are shifted by 180°. The eccentric body shaft 12 is inserted through the center of the second gear 50 and supports the second gear 50.

[0032] The eccentric body shaft 12 is supported by the first carrier 18 and the second carrier 20 via a pair of eccentric body shaft bearings 34. The non-input side eccentric body shaft bearing 34 is provided on the non-input side of the external gear 14, between the eccentric body shaft 12 and an eccentric body shaft hole 182 of the first carrier 18. The input side eccentric body shaft bearing 34 is provided on the input side of the external gear 14, between the eccentric body shaft 12 and an eccentric body shaft hole 202 of the second carrier 20. The eccentric body shaft bearing 34 in this example is a tapered roller bearing.

[0033] (2nd gear) Rotational power is transmitted to the second gear 50 from a driving source 6 (not shown) via the gear unit 4. In this embodiment, the second gear 50 is provided adjacent to one end side of each eccentric body shaft 12. The second gear 50 is connected to each eccentric body shaft 12, for example, by a spline, and is integrated in the rotation direction. Only one second gear 50 is shown in FIG. 1. The second gear 50 meshes with the internal teeth 424.

[0034] (Internal gear) The internal gear 16 meshes with the external gear 14. The internal gear 16 is provided on the inner periphery of the third casing 16. The internal gear 16 of this embodiment has an annular internal gear body 162 fixed to the inner periphery of the third casing 16, and an outer pin 17. The input side end face of the internal gear body 162 axially contacts a protruding portion 227 protruding toward the inner periphery of the third casing 16, and these are connected by a connecting tool such as a bolt B5.

[0035] The outer pins 17 are arranged in each of a plurality of pin grooves formed at intervals in the circumferential direction in the internal gear body 162. The outer pins 17 are cylindrical pin members rotatably supported by the internal gear body 162. The outer pins 17 may be hollow members, but are solid members in this embodiment. The outer pins 17 form the internal teeth of the internal gear 16. The number of outer pins 17 (the number of internal teeth) of the internal gear 16 is slightly more (by one in this example) than the number of external teeth of the external gear 14.

[0036] (External gear) The external gear 14 is provided individually corresponding to each of the multiple eccentric parts 122. The external gear 14 is rotatably supported by the corresponding eccentric part 122 via an eccentric bearing 32 (eccentric roller). Three shaft holes 144 and three oscillating holes 143 are formed at predetermined intervals in the external gear 14 at positions offset from the axis of the external gear 14.

[0037] The shaft holes 144 are provided at the same radial position and at intervals of 120°. The shaft holes 144 penetrate in the axial direction and receive the shaft portion 185. The shaft hole 144 is formed to be larger than the outer diameter of the shaft portion 185 and has a size such that it does not come into contact with the shaft portion 185.

[0038] The swing holes 143 are provided at the same radial position at intervals of 120°. The swing holes 143 penetrate in the axial direction, and the eccentric portion 122 of the eccentric body shaft 12 is inserted through them. The swing hole 143 is formed to be larger than the outer diameter of the eccentric portion 122, and a plurality of eccentric bearings 32 are interposed between the swing hole 143 and the eccentric portion 122. The plurality of eccentric bearings 32 are arranged at approximately equal intervals around the eccentric portion 122, and smoothly transmit the eccentric motion of the eccentric portion 122 to the swing hole 143.

[0039] The external gear 14 is provided with a central hole 142 through which the center pipe 52 passes. The central hole 142 is a hole provided in the radial center of the external gear 14, and is formed to be larger than the outermost diameter of the center pipe 52 and has a size such that it does not come into contact with the center pipe 52. There are no limitations on the shape of the central hole 142, but the central hole 142 in this example is circular.

[0040] The external gear 14 has wavy teeth formed on its outer periphery, and these teeth move in contact with the internal gear 16, allowing the external gear 14 to oscillate within a plane normal to the central axis.

[0041] The first carrier 18 and the second carrier 20 are connected via a shaft portion 185. The shaft portion 185 is provided at a position radially offset from the axis of the external gear 14. The shaft portion 185 in Fig. 1 is a portion that extends in the axial direction from the first carrier 18 toward the second carrier 20, and is formed integrally with the first carrier 18. The shaft portion 185 is inserted with a gap through a shaft hole 144 formed through the external gear 14.

[0042] The shaft portion 185 has a tip portion in contact with an end face of the second carrier 20 on the non-input side, and is fixed to the second carrier 20. When the shaft portion 185 is fixed to the second carrier 20, it is positioned by a positioning pin (not shown) and fixed by a bolt B1. The shaft portion 185 functions as a connecting portion that contributes to the connection between the first carrier 18 and the second carrier 20.

[0043] An oil seal 28 is provided between the first carrier 18 and the internal gear 16. The oil seal 28 is disposed on the anti-input side of the first main bearing 24.

[0044] One of the first carrier 18 and the internal gear 16 functions as an output member that outputs rotational power to a driven device, and the other functions as a fixed member that is fixed to an external member for supporting the reduction gear unit 10. In this embodiment, the output member is the first carrier 18, and the fixed member is the internal gear 16. The internal gear 16 may be the output member, and the first carrier 18 may be the fixed member.

[0045] The operation of the transmission device 100 configured as above will be described. When rotation is input from the driving source 6 to the first gear 41, the ring gear 42 rotates around the central axis La in conjunction with the rotation of the first gear 41. The rotation of the ring gear 42 distributes the rotational power to the three second gears 50 meshing with the internal teeth 424 of the ring gear 42, and the three second gears 50 rotate in the same phase. When the three second gears 50 rotate, the eccentric portion 122 of the eccentric body shaft 12 rotates around the rotation center line passing through the eccentric body shaft 12, and the external gear 14 oscillates due to the eccentric portion 122. When the external gear 14 oscillates, the meshing positions of the external gear 14 and the outer pin 17 of the internal gear 16 are shifted sequentially. As a result, each time the eccentric shaft 12 rotates once, one of the external gear 14 and the internal gear 16 rotates by an amount corresponding to the difference between the number of teeth of the external gear 14 and the number of outer pins 17 of the internal gear 16. In this embodiment, the external gear 14 rotates on its axis, and reduced rotation is output from the first carrier 18. A center pipe 52 is fixed to the first carrier 18, and the center pipe 52 rotates integrally with the first carrier 18.

[0046] The features of the transmission device 100 configured as above will be described. The transmission device 100 of this embodiment includes a first gear 41, a ring gear 42 having an outer peripheral surface on which external teeth 422 meshing with the first gear 41 are provided and an inner peripheral surface on which internal teeth 424 are provided, a second gear 50 which meshes with the internal teeth 424 of the ring gear 42, a speed reduction unit 10 which reduces the speed input from the second gear 50 and outputs it, and a thrust bearing means 45 which is disposed on the side of the axis Lb of the second gear 50 on which the internal teeth 424 are provided and which receives a thrust load.

[0047] According to this configuration, the thrust bearing means 45 is disposed radially on the inner teeth 424 side of the axis Lb of the second gear 50, thereby increasing the thrust rigidity of the ring gear 42. Increasing the thrust rigidity reduces the deflection of the ring gear 42, and reduces the deterioration of rotational accuracy caused by the deflection. Furthermore, under conditions of constant rigidity, the ring gear 42 can be made thinner, which is advantageous for weight reduction. As a result, a transmission device capable of ensuring the rigidity of the ring gear 42 can be provided. The above is a description of the first embodiment.

[0048] [Second embodiment] The configuration of a transmission device 100 according to a second embodiment of the present disclosure will be described with reference to Fig. 2. Fig. 2 is a side cross-sectional view showing the transmission device 100 according to the second embodiment. The transmission device 100 of this embodiment differs from the first embodiment in that the thrust bearing means and the radial bearing means are configured as an integrated bearing, but the other configurations are similar. Duplicate explanations will be omitted, and the description will focus on the configurations that differ from the first embodiment.

[0049] The gear unit 4 of this embodiment is provided with an integrated bearing 47, with the thrust bearing means 45, radial bearing means 46 and connecting member 44 eliminated from the first embodiment. The integrated bearing 47 may be a bearing in which the thrust bearing means and the radial bearing means are integrated, such as a cross roller bearing or a double row angular bearing. In this example, the integrated bearing 47 is a cross roller bearing. The integrated bearing 47 has a first raceway ring 473 (inner ring) and a second raceway ring 474 (outer ring) which face each other in the radial direction with a rolling element 472 in between. The rolling element 472 is a cylindrical roller.

[0050] The first raceway 473 is disposed radially inside the rolling element 472, and is fitted and fixed to the outer peripheral surface of the annular protruding portion 234 that protrudes toward the non-input side of the second casing 23. In this example, the input side of the first raceway 473 is positioned by abutting against a stepped seat provided around the outer peripheral surface of the annular protruding portion 234. The first raceway 473 has a plurality of through holes 476 drilled in the axial direction at positions offset from the radial center. The plurality of through holes 476 are provided at predetermined intervals in the circumferential direction.

[0051] The second casing 23 has a plurality of female threads 239 drilled in the axial direction at positions offset from the radial center. The multiple female threads 239 are provided at predetermined intervals in the circumferential direction at positions overlapping with the multiple through holes 476 of the first race 473 when viewed from the axial direction. The first race 473 is fixed to the second casing 23 by screwing a bolt B4 passing through the through hole 476 into the female threads 239. In this example, the neck of the bolt B3 engages with a seat provided in a stepped shape around the inner circumferential surface of the through hole 476.

[0052] The second raceway 474 is an annular member disposed radially outside the rolling body 472 and connected to the inner circumferential side of the ring gear 42. In particular, the second raceway 474 is fitted to an inner circumferential step 425 of the ring gear 42. The second raceway 474 has a plurality of female threads 475 drilled in the axial direction at a position offset from the radial center. The female threads 475 are provided at predetermined intervals in the circumferential direction at positions overlapping with the through holes 427 of the ring gear 42 as viewed from the axial direction. The second raceway 474 is fixed to the ring gear 42 by screwing the bolt B3 that passes through the through hole 427 into the female thread 475. In this example, the neck of the bolt B3 is engaged with a seat that is provided in a stepped shape around the inner circumferential surface of the through hole 427. 2, the first raceway 473 is disposed radially inward from the internal teeth 424, the rolling elements 472 are disposed so as to overlap with the internal teeth 424 in the axial direction, and the second raceway 474 is disposed radially outward from the internal teeth 424. In other words, at least a portion of the integrated bearing 47 is disposed radially outward from the internal teeth 424.

[0053] The second embodiment operates in the same manner as the first embodiment, and provides the same actions and effects. In addition, in the transmission device 100 of this embodiment, the thrust bearing means and the radial bearing means are configured as an integrated bearing, so that the number of parts can be reduced, and the manufacturing man-hours can be reduced. Furthermore, by integrating these, it is possible to easily realize a configuration in which the thrust bearing means 45 overlaps with the radial bearing means 46 when viewed from the radial direction.

[0054] The above describes in detail the examples of the embodiments of the present invention. The above-mentioned embodiments are merely examples of the implementation of the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components are possible within the scope of the invention as defined in the claims. In the above-mentioned embodiments, the contents for which such design changes are possible are described with notations such as "in the embodiment" and "in the embodiment", but this does not mean that design changes are not permitted for contents without such notations. In addition, hatching on the cross sections of the drawings does not limit the material of the objects to which the hatching is applied.

[0055] The following describes the modified examples. In the drawings and description of the modified examples, the same or equivalent components and members as those in the embodiment are denoted by the same reference numerals. Descriptions that overlap with the embodiment will be omitted as appropriate, and the description will focus on configurations that differ from the embodiment.

[0056] [Variations] In the description of the embodiment, an example has been given in which the reduction unit 10 is a so-called distribution type gear mechanism, but the gear mechanism of the reduction unit 10 is not limited to this. For example, the transmission device of the present disclosure can be applied to a center crank type gear mechanism in which an eccentric shaft (crank shaft) is disposed on the rotation center axis of an internal gear, and can also be applied to various known reducers such as a simple planetary gear reduction device, a flexure mesh reduction device, and a parallel shaft reducer.

[0057] In the description of the embodiment, an example in which the number of eccentric body shafts 12 and second gears 50 is three has been shown, but the number of eccentric body shafts 12 and second gears 50 may be one, two, four or more.

[0058] In the description of the embodiment, an example in which the number of external gears 14 is two has been shown, but the number of external gears 14 may be one or three or more.

[0059] There is no limitation on the configuration of each bearing of the gear device, and each bearing may have a different configuration from that in the embodiment.

[0060] Each of the above-described modified examples provides the same functions and effects as the embodiment.

[0061] Any combination of the components and modifications of the above-described embodiments is also useful as an embodiment of the present invention. A new embodiment resulting from the combination has the combined effects of the respective embodiments and modifications. [Explanation of symbols]

[0062] 4 gear unit, 10 reduction portion, 41 first gear, 42 ring gear, 45 thrust bearing means, 46 radial bearing means, 50 second gear, 422 external teeth, 424 internal teeth, 452, 472 rolling elements, 453, 473 first raceway ring, 454, 474 second raceway ring, 100 transmission device.

Claims

1. A first gear; a ring gear having an outer circumferential surface provided with external teeth that mesh with the first gear and an inner circumferential surface provided with internal teeth; a second gear that meshes with the internal teeth of the ring gear; a thrust bearing means disposed on the inner teeth side of the axis of the second gear and configured to receive a thrust load of the ring gear; A transmission device comprising:

2. A radial bearing means for receiving a radial load of the ring gear, 2. The transmission device according to claim 1, wherein said thrust bearing means overlaps said radial bearing means when viewed in a radial direction.

3. A radial bearing means for receiving a radial load of the ring gear, 2. The transmission device according to claim 1, wherein said thrust bearing means and said radial bearing means are constructed as separate bearings.

4. A transmission device described in any one of claims 2 to 3, characterized in that the radial bearing means is arranged radially inward from the inner teeth and radially outward from the thrust bearing means.

5. The thrust bearing means has a first raceway and a second raceway facing each other with a rolling element therebetween, the ring gear is directly coupled to the second raceway; A casing that houses the ring gear, 5. The transmission device according to claim 1, wherein the first bearing ring is axially connected to the casing.

6. 6. The transmission device according to claim 1, wherein at least a portion of the thrust bearing means is disposed radially outward from the internal teeth.

7. 7. The transmission device according to claim 1, wherein the thrust bearing means overlaps with the external teeth when viewed in the axial direction.

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