Eccentric oscillation-type gear device

Abstract

To provide an eccentric oscillation-type gear device which enables improvement of influence caused on a slide part of a gear by a load received from the output side.SOLUTION: An eccentric oscillation-type gear device 100 comprises: eccentric bodies 31, 32; a first external gear 14 and a second external gear 15 that are oscillated with a prescribed eccentric amount by the eccentric bodies 31, 32; a carrier 35 provided at the side axially opposite to the second external gear 15 with respect to the first external gear 14; and a plurality of inner pins 48 that are integrated by the carrier 35 and that penetrate through the first external gear 14 and the second external gear 15. An eccentric amount of the second eccentric body 32 corresponding to the second external gear 15 is larger than an eccentric amount of the first eccentric body 31 corresponding to the first external gear 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an eccentric oscillating gear device. [Background technology]

[0002] There is known a reduction gear that reduces the speed of rotation input to an input shaft and outputs the reduced speed. For example, Patent Document 1 describes a reduction gear including an external gear, an internal gear, a plurality of carrier pins that rotate inscribed in carrier pin holes of the external gear, and a carrier having an output shaft that outputs the rotation of the rotation component of the external gear via the carrier pins. In this device, the carrier has a support portion that connects the plurality of carrier pins, and one end of each carrier pin is fixed to the support portion and cantilevered by the support portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-170831 A Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have come to the following new realization regarding eccentric oscillating gear devices. In the reduction gear described in Patent Document 1, the carrier pin is supported at one end by the carrier on the output side. The root portion on the side closer to the carrier supporting the carrier pin has higher rigidity than the tip portion on the side farther from the carrier supporting the carrier pin. For this reason, it is considered that the output torque generated in the carrier is not shared equally by the external gear on the output side closer to the carrier and the external gear on the input side farther from the carrier, and the influence on each sliding portion of the external gear is not uniform. From these findings, the inventors have come to the realization that, in the reduction gear transmission described in Patent Document 1, it is important to further improve the configuration with regard to the effect that the load received from the output side has on the gears, for example.

[0005] The present invention has been made in consideration of these problems, and one of its objects is to provide an eccentric oscillating gear device that can improve the effect that the load received from the output side has on the sliding parts of the gears. [Means for solving the problem]

[0006] In order to solve the above problems, one embodiment of the eccentric oscillating gear device of the present invention is an eccentric oscillating gear device comprising an eccentric body, a first external gear and a second external gear that oscillate by a predetermined eccentricity due to the eccentric body, a carrier provided on the axially opposite side of the first external gear from the second external gear, and a plurality of inner pins that are integrated by the carrier and pass through the first external gear and the second external gear, wherein the eccentricity of the second eccentric body corresponding to the second external gear is greater than the eccentricity of the first eccentric body corresponding to the first external gear.

[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, it is possible to provide an eccentric oscillating gear device capable of improving the effect that the load received from the output side has on the sliding parts of the gears. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side cross-sectional view that shows a schematic diagram of an eccentric oscillating gear device according to an embodiment. [Diagram 2] FIG. 2 is a front view showing a schematic view of the eccentric oscillating gear device of FIG. [Diagram 3] 2 is an enlarged cross-sectional view showing the eccentric body and its surroundings of the eccentric oscillating gear device of FIG. 1. 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] [Embodiment] First, the overall configuration of an eccentric oscillating gear device 100 according to an embodiment (hereinafter sometimes referred to as "gear device 100") will be described with reference to Figs. 1 to 3. Fig. 1 is a cross-sectional side view showing an example of the gear device 100. Fig. 2 is a front view of the gear device 100, showing the exposed interior. Fig. 3 is a cross-sectional enlarged view of the periphery of eccentric bodies 31, 32.

[0013] The gear device 100 mainly includes a crankshaft 20, external gears 14, 15, an internal gear 16, eccentric body bearings 17, 18, eccentric bodies 31, 32, a carrier 35, an output flange 36, a main bearing 37, crankshaft bearings 39, 40, an inner pin 48, casings 61, 62, and an input cover 63. Hereinafter, the direction along the central axis La of the internal gear 16 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. In addition, the side of the external gears 14, 15 on which the carrier 35 is provided in the axial direction (left side in the drawing) is referred to as the output side, and the opposite side (right side in the drawing) is referred to as the input side.

[0014] The gear device 100 has a speed reduction mechanism that reduces the speed of rotation input to the crankshaft 20 from a power source such as a motor (not shown) and outputs the reduced speed from the output flange 36. There are no limitations on this reduction mechanism as long as it is capable of reducing the speed of the input rotation and outputting it, and various mechanisms can be used. The gear device 100 of the embodiment is an eccentric oscillating gear device that rotates the external gear by oscillating the external gear that meshes with the internal gear, and outputs the generated rotation component from the output flange 36 to a driven member. The gear device 100 of the embodiment is a center crank type in which the central axis of the crankshaft 20 is coaxial with the central axis La of the internal gear.

[0015] The crankshaft 20 is a shaft body extending from the input side to the output side in the axial direction, and is rotated around the rotation center line La by the input rotation. On the outer periphery of the crankshaft 20, a first shaft portion 22, a first eccentric portion 24, a second eccentric portion 25, and a second shaft portion 26 are provided in this order from the output side to the input side. The first shaft portion 22 and the second shaft portion 26 support inner rings of crankshaft bearings 39, 40. The first eccentric portion 24 and the second eccentric portion 25 are cylindrical portions having a larger diameter than the first shaft portion 22, and are eccentric as described below. The second shaft portion 26 is a cylindrical portion having the same diameter as the first shaft portion 22.

[0016] A first shaft portion 22 on the output side of the crankshaft 20 is supported by the carrier 35 via a crankshaft bearing 39. A second shaft portion 26 on the input side of the crankshaft 20 is supported by the input cover 63 via a second crankshaft bearing 40. In other words, the crankshaft 20 is supported rotatably with respect to the carrier 35 and the input cover 63. The input cover 63 is connected to the input sides of casings 61, 62 (described later) using bolts B1, and covers the input side of the reduction mechanism.

[0017] The crankshaft bearing 39 is disposed between the carrier 35 and the shaft portion 22 of the crankshaft 20, and the crankshaft bearing 40 is disposed between the input cover 63 and the shaft portion 26 of the crankshaft 20. Various known bearing mechanisms can be used for the crankshaft bearings 39, 40. In this example, the crankshaft bearings 39, 40 are ball bearings having spherical rolling elements.

[0018] The crankshaft 20 is an eccentric body shaft having a plurality of eccentric parts 24, 25 for oscillating the external gears 14, 15, and may be referred to as an input shaft. The axial cores of the eccentric parts 24, 25 are eccentric with respect to the rotation center line of the crankshaft 20 (coincident with the central axis La). In this embodiment, two eccentric parts 24, 25 are provided, and the eccentric phases of the adjacent eccentric parts 24, 25 are shifted by 180°. The eccentric parts 24, 25 constitute eccentric bodies 31, 32, which will be described later. Eccentric body bearings 17, 18 are disposed on the outer periphery of the eccentric parts 24, 25. The eccentric body bearings 17, 18 in this example are roller bearings having a plurality of cylindrical rolling elements 51, 52. 3, symbols D1 and D2 indicate the diameters of the rolling elements 51 and 52 (the outer diameters of the cross sections perpendicular to the axial direction of the rolling elements), and symbols T1 and T2 indicate the axial lengths of the rolling elements 51 and 52.

[0019] The eccentric bodies 31, 32 include a first eccentric body 31 that oscillates the first external gear 14 by a predetermined eccentric amount e1, e2, and a second eccentric body 32 that oscillates the second external gear 15. In this specification, the distance between a predetermined rotation axis and the central axis of the external gear is referred to as the eccentric amount of the eccentric body. In the example of FIG. 3, the distance e1 from the central axis La of the internal gear 16 to the rotation center line L1 of the first external gear 14 is referred to as the eccentric amount e1 of the first eccentric body 31, and the distance e2 from the central axis La to the rotation center line L2 of the second external gear 15 is referred to as the eccentric amount e2 of the first eccentric body 31. The eccentric amount may be the distance from the rotation center axis of the carrier to the central axis of the external gear.

[0020] In the embodiment, the eccentric bodies 31, 32 have eccentric parts 24, 25 formed on the outer periphery of the crankshaft 20, which is a shaft body, and eccentric body bearings 17, 18 arranged on the outer periphery of the eccentric parts 24, 25. That is, the first eccentric body 31 has the first eccentric part 24 and the first eccentric body bearing 17 arranged on the outer periphery of the first eccentric part 24. The second eccentric body 32 has the second eccentric part 25 and the second eccentric body bearing 18 arranged on the outer periphery of the second eccentric part 25. Therefore, the eccentricity e1 of the first eccentric body 31 can be set by the eccentricity of the first eccentric part 24 and the diameter D1 of the rolling element of the first eccentric body bearing 17, and the eccentricity e2 of the second eccentric body 32 can be set by the eccentricity of the second eccentric part 25 and the diameter D2 of the rolling element of the second eccentric body bearing 18. Diameters D1 and D2 are the diameters of the rolling elements as viewed from the axial direction.

[0021] The external gears 14, 15 are assembled to the outer circumference of the eccentric parts 24, 25 via the eccentric bearings 17, 18 so as to be able to oscillate. The external gears 14, 15 are internally meshed with the internal gear 16 while oscillating. The outer circumference of the external gears 14, 15 has wavy teeth formed thereon, and these teeth move while in contact with the internal gear 16, so that the external gears 14, 15 can oscillate within a plane normal to the central axis. Between the external gears 14, 15, an annular crease W1 is disposed to maintain the axial distance between the external gears 14, 15 within a predetermined range. Between the external gear 15 and the input cover 63, an annular end washer W2 is disposed to regulate the axial position of the external gears 14, 15. The outer edge of the end washer W2 is sandwiched between the input side end face of the second casing 62 and the input cover 63.

[0022] The internal gear 16 meshes with the external gears 14, 15. The internal gear 16 in this embodiment is composed of internal teeth that are integrally provided on the inner periphery of the second casing 62. The number of internal teeth of the internal gear 16 is slightly more (by two in this example) than the number of external teeth of the external gears 14, 15.

[0023] The external gears 14, 15 have a plurality of inner pin holes 46, 47 formed at positions offset from their axis. An inner pin 48 passes through the inner pin holes 46, 47. A cylindrical inner roller 49 is disposed on the outer periphery of the inner pin 48. The inner roller 49 functions as a sliding promoter for smoothing sliding with the inner pin holes 46, 47. The outer diameter of the inner roller 49 is smaller than the inner diameter of the inner pin holes 46, 47 by twice the amount of eccentricity.

[0024] A gap is provided between the inner roller 49 and the inner pin 48 to provide play for absorbing the oscillation components of the external gears 14, 15, and the inner pin 48 is always in contact with a part of the inner pin holes 46, 47 via the inner roller 49. The inner pin 48 revolves around the axis of the crankshaft 20 in synchronization with the rotation components of the external gears 14, 15, and rotates the carrier 35 around the axis of the crankshaft 20. The inner pin 48 contributes to the transmission of power between the carrier 35 and the external gears 14, 15.

[0025] The casings 61, 62 have a cylindrical shape that constitutes the outer shell of the gear device 100. The casings 61, 62 include a first casing 61 and a second casing 62 connected to the input side of the first casing 61. The first casing 61 mainly surrounds the main bearing 37 and the oil seal S1. The internal gear 16 is provided on the inner circumferential surface of the second casing 62. The first casing 61 and the second casing 62 are connected using bolts B2.

[0026] The carrier 35 has a hollow circular shape. The carrier 35 is disposed on the side of the output side of the external gears 14, 15. The input cover 63 is disposed on the side of the input side of the external gears 14, 15. The carrier 35 is rotatably supported with respect to the casings 61, 62 via the main bearings 37. The carrier 35 rotatably supports the output side of the crankshaft 20 via a first crankshaft bearing 39. The input cover 63 rotatably supports the input side of the crankshaft 20 via a second crankshaft bearing 40.

[0027] The output flange 36 is a hollow circular member connected to the output side of the carrier 35. The output flange 36 is surrounded by a first casing 61, and an oil seal S1 is disposed between the output flange 36 and the first casing 61. The rotation input to the crankshaft 20 is reduced in speed by the reduction mechanism and output from the output flange 36 via the carrier 35.

[0028] The main bearing 37 is disposed between the first casing 61 and the carrier 35. The main bearing 37 can employ various known bearing mechanisms, and the main bearing 37 in this example is a cross roller bearing.

[0029] The inner pins 48 are rod-shaped members extending in the axial direction from the input side of the carrier 35 toward the input cover 63, and a plurality of inner pins 48 are provided at predetermined intervals in the circumferential direction. The plurality of inner pins 48 pass through the inner pin holes 46, 47 of the first external gear 14 and the second external gear 15. The plurality of inner pins 48 are integrated by the carrier 35. Configurations in which the inner pins 48 are integrated include a configuration in which the carrier 35 and the plurality of inner pins 48 are integrally formed from a single piece of material, and a configuration in which the inner pins 48 are formed separately from the carrier 35 and connected to the carrier 35. The tip of the inner pin 48 faces the end washer W2 in a contacting or non-contacting state.

[0030] The deceleration operation of the gear device 100 will be described. When rotational power is transmitted to the crankshaft 20, the eccentric bodies 31, 32, which are composed of the eccentric parts 24, 25 of the crankshaft 20 and the eccentric body bearings 17, 18, rotate around a rotation center line passing through the crankshaft 20, and the eccentric bodies 31, 32 cause the external gears 14, 15 to oscillate. At this time, the external gears 14, 15 oscillate so that their rotation center lines L1, L2 rotate around the central axis La of the internal gear 16. When the external gears 14, 15 oscillate, the meshing positions of the internal teeth of the external gears 14, 15 and the internal gear 16 are shifted sequentially. As a result, one of the external gears 14, 15 and the internal gear 16 rotates on its own axis by an amount equivalent to the difference between the number of teeth of the external gears 14, 15 and the number of teeth of the internal gear 16 every time the crankshaft 20 rotates once. In the embodiment, the external gears 14, 15 rotate on their axes, and reduced rotation is output from the output flange 36 via the carrier 35. As the output flange 36 rotates, a driven member connected to the output flange 36 is rotationally driven.

[0031] Next, the deflection of the inner pin of the gear device and its effects will be described. In the gear device, the output torque is transmitted to the carrier via the inner pin due to the oscillation of the external gear. The rigidity of the inner pin at the portion away from the support end is lower than the rigidity of the portion near the support end. When the external gear oscillates, a load is applied to the inner pin in contact with the external gear, causing the inner pin to deflect and escape. When the inner pin deflects, the torque transmission function of the inner pin decreases accordingly. In this case, among the multiple external gears, the gear corresponding to the portion where the inner pin is less deflected bears a larger torque than the other gears, and damage to each sliding part of this gear occurs earlier than the others.

[0032] When the inner pin is supported at one end, the base end of the inner pin is deflected less than the tip end, and the external gear closer to the base end bears a larger share of torque than the external gear closer to the tip end. As a result, relatively large stress is applied to the sliding parts of the external gear on the base end side and the corresponding internal gear, and deterioration progresses faster than other sliding parts. When the inner pin is supported at both ends, the deflection of the central part away from both support ends is greater than that near the support ends. For example, in the case of three external gears, the two external gears near the support ends bear a larger share of torque than the central external gear, and are subjected to a relatively large torque, so that damage to each sliding part of these gears occurs faster than the others.

[0033] In addition, the load received from the output side is applied to the carrier as an external torque. This external torque is transmitted to the external gear via the inner pin. As with the output torque, the gears corresponding to the parts of the inner pin with less deflection receive a larger torque than the other gears, and damage to each sliding part occurs earlier. From these facts, the inventors have come to the realization that it is important to further improve the configuration regarding the effect of the load received from the output side on the gears.

[0034] In view of these findings, in the gear device 100 of the embodiment, the eccentricity e2 of the second eccentric body 32 corresponding to the second external gear 15 is set to be larger than the eccentricity e1 of the first eccentric body 31 corresponding to the first external gear 14 (hereinafter, sometimes referred to as an "eccentricity adjustment structure"). Because the eccentricity e2 is larger than the eccentricity e1, the substantial amount of oscillation of the second external gear 15 increases, and the amount of escape caused by the bending of the inner pin 48 can be offset to some extent. As a result, the torque share of the second external gear 15 increases and the torque share of the first external gear 14 decreases, making it possible to make the effects on the sliding parts of these gears more uniform.

[0035] From the viewpoint of expanding the range of applications, it is desirable for the gear device to be small and lightweight. Therefore, in the gear device 100 of the embodiment, the inner pin 48 is supported by the carrier 35 in a cantilevered manner in order to reduce the size and weight. Since the inner pin 48 is more easily bent in a cantilevered manner than when supported at both ends, the effect of reducing the impact of the eccentricity adjustment structure of the present disclosure on the sliding parts is more easily achieved. Note that the inner pin 48 may be supported at both ends.

[0036] There is no limitation on the means for making the eccentricity e2 greater than the eccentricity e1, and various means can be used. Examples of the means for making the eccentricity e2 greater than the eccentricity e1 are given below. (1) The amount of eccentricity of eccentric portion 25 is made larger than the amount of eccentricity of eccentric portion 24. In this case, the amount of eccentricity e2 can be made larger than the amount of eccentricity e1. (2) The diameter D2 of the rolling element 52 of the eccentric bearing 18 is made larger than the diameter D1 of the rolling element 51 of the eccentric bearing 17. In this case, the amount of eccentricity e2 can be made larger than the amount of eccentricity e1. (3) Combine (1) and (2) above.

[0037] In the case of (2) above, for example, the inner diameter 44 of the external gear 14 and the inner diameter 45 of the external gear 15 are the same. In this case, the diameter D2 of the rolling element 51 is larger than the diameter D1 of the rolling element 52, so the gap between the rolling element 51 and the inner diameter 44 of the external gear 14 is larger than the gap between the rolling element 52 and the inner diameter 45 of the external gear 15. In this case, the external gear 14 and the external gear 15 rotate so as to eliminate this gap when the external gears 14 and 15 mesh with the internal gear 16, so that the rotation center line L1 of the external gear of the external gear 14 is closer to the central axis of the internal gear than the rotation center line L2 of the external gear 15. Therefore, the eccentricity e2 can be made larger than the eccentricity e1.

[0038] In the above, the case where the inner diameter 44 of the external gear 14 and the inner diameter 45 of the external gear 15 are the same has been described, but this is not limiting, and the inner diameter 44 of the external gear 14 and the inner diameter 45 of the external gear 15 may be different. Even in this case, if the gap between the rolling element 51 and the inner diameter 44 of the external gear 14 is larger than the gap between the rolling element 52 and the inner diameter 45 of the external gear 15, the eccentricity e2 can be made larger than the eccentricity e1.

[0039] The features of the eccentric oscillating gear device 100 configured as above will be described. The eccentric oscillating gear device 100 is an eccentric oscillating gear device including eccentric bodies 31, 32, a first external gear 14 and a second external gear 15 that oscillate by a predetermined eccentricity due to the eccentric bodies 31, 32, a carrier 35 provided on the axially opposite side of the second external gear 15 with respect to the first external gear 14, and a plurality of inner pins 48 that are integrated by the carrier 35 and pass through the first external gear 14 and the second external gear 15, in which the eccentricity e2 of the second eccentric body 32 corresponding to the second external gear 15 is greater than the eccentricity e1 of the first eccentric body 31 corresponding to the first external gear 14.

[0040] According to this configuration, even if the deflection of the portion of the inner pin 48 away from the carrier 35 is large, the eccentricity e2 on the side away from the carrier 35 is greater than the eccentricity e1 on the side closer to the carrier 35, so the difference in deflection is compensated for and the difference in the amount of oscillation of the first external gears 14, 15 is reduced. As a result, the difference in torque distribution between these gears and the resulting difference in the effect on each sliding portion of the gears can be reduced.

[0041] As an example, the multiple inner pins 48 are supported in a cantilever manner by the carrier 35. In this case, the member supporting the tip side of the carrier 35 can be omitted, so the number of parts is reduced compared to a case where both ends are supported, which is advantageous for miniaturization and weight reduction. In addition, since a cantilever support is more flexible than a case where both ends are supported, the effect of reducing the impact of the eccentricity adjustment structure of the present disclosure on each sliding portion of the gears can be easily achieved.

[0042] As an example, the eccentric bodies 31, 32 have eccentric parts 24, 25 formed on the outer periphery of the shaft body and eccentric body bearings 17, 18 arranged on the outer periphery of the eccentric parts 24, 25, and the amount of eccentricity of the eccentric part 25 of the second eccentric body 32 is larger than the amount of eccentricity of the eccentric part 24 of the first eccentric body 31. In this case, by providing a difference in the amount of eccentricity of the eccentric parts 24, 25, the difference in the amount of eccentricity of the eccentric bodies 31, 32 can be easily set.

[0043] As an example, the eccentric bodies 31, 32 have eccentric parts 24, 25 formed on the outer periphery of the shaft body and eccentric body bearings 17, 18 arranged on the outer periphery of the eccentric parts 24, 25, and the diameter D2 of the rolling element 51 of the eccentric body bearing 18 of the second eccentric body 32 is larger than the diameter D1 of the rolling element 52 of the eccentric body bearing 17 of the first eccentric body 31. In this case, by providing a difference in the diameters of the rolling elements of the eccentric body bearings 17, 18, the difference in the amount of eccentricity of the eccentric bodies 31, 32 can be easily set.

[0044] The present invention has been described above based on the embodiments. These embodiments are illustrative, and various modifications and changes are possible within the scope of the claims of the present invention, and it is understood by those skilled in the art that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the description and drawings in this specification should be treated as illustrative rather than restrictive.

[0045] (Modification) 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.

[0046] In the description of the embodiment, (1) the eccentricity of the eccentric portion 25 is made larger than the eccentricity of the eccentric portion 24, (2) the diameter D2 of the rolling element 51 of the eccentric body bearing 18 is made larger than the diameter D1 of the rolling element 52 of the eccentric body bearing 17, or (3) (1) and (2) are combined to make the eccentricity e2 larger than the eccentricity e1, but the present invention is not necessarily limited to these. For example, in the description of the embodiment, an example was shown in which the thickness of the inner roller 49 (the thickness between the inner peripheral surface and the outer peripheral surface) is constant in the axial direction, but the eccentricity e2 can also be made larger than the eccentricity e1 by making the thickness of the portion of the inner roller 49 in contact with the second external gear 15 larger than the thickness of the portion of the inner roller 49 in contact with the first external gear 14.

[0047] In the description of the embodiment, an example was shown in which the axial lengths T1 and T2 of the rolling elements 51 and 52 of the eccentric bearings 17 and 18 are the same, but the present invention is not limited to this. The axial lengths T1 and T2 may be different from each other. For example, the axial length T2 of the rolling element 52 of the second eccentric bearing 18 may be greater than the axial length T1 of the rolling element 51 of the first eccentric bearing 17.

[0048] In the description of the embodiment, an example was shown in which the internal gear 16 is configured with internal teeth formed integrally with the inner circumference of the casing, but the present invention is not limited to this. The internal gear may be configured with a cylindrical pin member rotatably supported in a pin groove provided in the inner circumference of the casing.

[0049] In the description of the embodiment, an example has been shown in which the gear device 100 includes two external gears 14, 15, but the present invention is not limited to this. The gear device may include three or more external gears.

[0050] In the description of the embodiment, an example has been shown in which the output rotation is output from the output flange 36 connected to the output side of the carrier 35, but the present invention is not limited to this. It is not essential to have an output flange, and the output rotation may be output from the carrier. Also, the output flange 36 side may be the fixed side, and the output rotation may be output from the casings 61, 62 side.

[0051] In the description of the embodiment, an example was given in which the main bearing 37 is a cross roller bearing, but the present invention is not limited to this. The main bearing may be a type of bearing other than a cross roller bearing, such as a pair of angular contact ball bearings or angular roller bearings.

[0052] In the description of the embodiment, the crankshaft bearings 39, 40 are ball bearings, but the present invention is not limited to this. The crankshaft bearings may be roller bearings or other bearings different from ball bearings.

[0053] In the description of the embodiment, an example has been shown in which the gear device 100 is a so-called center crank type eccentric oscillating gear device, but the present invention is not limited to this. For example, the gear device may be a so-called distributed type eccentric oscillating gear device in which multiple crankshafts are provided at positions offset from the central axis of the internal gear.

[0054] Each of these modified examples provides the same functions and effects as the embodiment.

[0055] Any combination of the above-described embodiments and modifications 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]

[0056] 14, 15 external gear, 16 internal gear, 17, 18 eccentric bearing, 24 eccentric portion, 25 eccentric portion, 31, 32 eccentric body, 36 output flange, 48 inner pin, 51, 52 rolling elements, 100 eccentric oscillating gear device.

Claims

1. An eccentric oscillating gear device comprising: an eccentric body; a first external gear and a second external gear that oscillate by a predetermined eccentricity due to the eccentric body; a carrier provided on the axially opposite side of the first external gear to the second external gear; and a plurality of inner pins that are integrated by the carrier and pass through the first external gear and the second external gear, An eccentric oscillating gear device in which an eccentricity amount of a second eccentric body corresponding to the second external gear is larger than an eccentricity amount of a first eccentric body corresponding to the first external gear.

2. 2. The eccentric oscillating gear device according to claim 1, wherein the inner pins are supported by the carrier in a cantilever manner.

3. The eccentric body has an eccentric portion formed on an outer periphery of a shaft body and an eccentric body bearing arranged on the outer periphery of the eccentric portion, 2. The eccentric oscillating gear device according to claim 1, wherein an amount of eccentricity of the eccentric portion of the second eccentric body is larger than an amount of eccentricity of the eccentric portion of the first eccentric body.

4. The eccentric body has an eccentric portion formed on an outer periphery of a shaft body and an eccentric body bearing arranged on the outer periphery of the eccentric portion, 2. The eccentric oscillating gear device according to claim 1, wherein a diameter of the rolling elements of the eccentric bearing of the second eccentric body is larger than a diameter of the rolling elements of the eccentric bearing of the first eccentric body.

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