Gear component, internally meshing planetary gear device, robot joint device, and method for manufacturing internally meshing planetary gear device

Abstract

To provide a gear component, an internally meshing planetary gear device, a robot joint device and a method for manufacturing an internally meshing planetary gear device, in which deformation is unlikely to occur when machining an external gear and the like.SOLUTION: An internally meshing planetary gear device includes an internal gear, and a plurality of planetary gears 3. The internally meshing planetary gear device rotates the plurality of planetary gears 3 relative to the internal gear about a rotational axis Ax1 by oscillating the plurality of planetary gears 3. A gear component used as each of the plurality of planetary gears 3 has a boss part 35 protruding from at least one surface in an axial direction along the rotational axis Ax1.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure generally relates to gear components, internally meshing planetary gear devices, joint devices for robots, and methods for manufacturing internally meshing planetary gear devices, and more particularly to gear components used as each of a plurality of planetary gears in an internally meshing planetary gear device having a plurality of planetary gears, an internally meshing planetary gear device, a joint device for robots, and methods for manufacturing internally meshing planetary gear devices. [Background technology]

[0002] As a related art, there is known an internally meshing planetary gear set (oscillating internally meshing planetary gear mechanism) that includes a plurality of planetary gears (external gears) attached to an input shaft via an eccentric body in a state that allows eccentric rotation, and an internal gear with which the plurality of planetary gears internally mesh (see, for example, Patent Document 1). This internally meshing planetary gear set rotates the output shaft at a predetermined reduction ratio relative to the input shaft by connecting the planetary gears to the output shaft via a means that transmits only the rotation component of the planetary gears. By providing a plurality of planetary gears, the internally meshing planetary gear set can increase the torque capacity that can be transmitted.

[0003] When manufacturing an internally meshing planetary gear device according to the related art, multiple planetary gears are manufactured by simultaneously machining the external teeth of multiple stacked blanks. In other words, the external teeth of the multiple planetary gears in the internally meshing planetary gear device are not formed individually, but are formed by batch machining. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-130395 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration of the related art described above, when machining the external teeth, it is necessary to fix multiple planetary gears (materials) in a stacked state. Therefore, if these multiple planetary gears are fixed tightly so as not to shift, problems may arise, such as deformation of the planetary gears.

[0006] An object of the present disclosure is to provide a gear component that is less likely to deform during processing of external teeth, etc., an internally meshing planetary gear device, a robot joint device, and a method for manufacturing an internally meshing planetary gear device. [Means for solving the problem]

[0007] A gear component according to one aspect of the present disclosure is a gear component used as each of a plurality of planetary gears in an internally meshing planetary gear set. The internally meshing planetary gear set includes an internal gear and the plurality of planetary gears. The internal gear has internal teeth. Each of the plurality of planetary gears has external teeth that partially mesh with the internal teeth. The internally meshing planetary gear set rotates the plurality of planetary gears relative to the internal gear about a rotation axis by oscillating the plurality of planetary gears. The gear component has a boss portion protruding from at least one surface in the axial direction along the rotation axis.

[0008] An internally meshing planetary gear device according to one aspect of the present disclosure includes the plurality of planet gears made of the gear components and the internal gear.

[0009] A robot joint device according to one embodiment of the present disclosure includes the internally meshing planetary gear device, a first member fixed to the internal gear, and a second member that rotates relative to the first member in accordance with the relative rotation of the planetary gear with respect to the internal gear.

[0010] A method for manufacturing an internally meshing planetary gear device according to one aspect of the present disclosure is a method for manufacturing an internally meshing planetary gear device, and includes a batch processing step of processing the plurality of planetary gears collectively while the plurality of planetary gears are coupled in the axial direction. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a gear component that is less likely to deform during processing of external teeth, an internally meshing planetary gear device, a robot joint device, and a method for manufacturing an internally meshing planetary gear device. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an actuator including an internally meshing planetary gear device according to a basic configuration. [Figure 2] FIG. 2 is a schematic exploded perspective view of the internal meshing planetary gear device as viewed from the input side of the rotary shaft. [Figure 3] FIG. 3 is a schematic exploded perspective view of the internal meshing planetary gear device as viewed from the output side of the rotary shaft. [Figure 4] FIG. 4 is a schematic cross-sectional view of the internal meshing planetary gear device. [Figure 5] FIG. 5 is a cross-sectional view taken along line A1-A1 in FIG. 4, showing the internal meshing planetary gear device. [Figure 6] FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 4, showing the internal meshing planetary gear device. [Figure 7] FIG. 7 is a schematic cross-sectional view of an internal meshing planetary gear device according to the first embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view showing only the planet gears of the internal meshing planetary gear device. [Figure 9] FIG. 9 is a schematic diagram of the internal gear and the planetary gears as viewed from the input side of the rotation shaft of the internal meshing planetary gear device. [Figure 10] FIG. 10 is an explanatory diagram that schematically shows a procedure for processing a plurality of planetary gears at once in the manufacturing method of the internal meshing planetary gear device. [Figure 11] FIG. 11 is a schematic diagram showing a robot joint device using the internal meshing planetary gear device. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Basic configuration) (1) Overview An overview of the internally meshing planetary gear device 1 according to this basic configuration will be described below with reference to Figures 1 to 4. All of the drawings referred to in this disclosure are schematic, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. For example, the tooth shapes, dimensions, number of teeth, etc. of the internal teeth 21 and external teeth 31 in Figures 1 to 4 are merely shown schematically for the purpose of explanation, and are not intended to be limited to the shapes shown in the drawings.

[0014] The internally meshing planetary gear device 1 (hereinafter also simply referred to as "gear device 1") according to this basic configuration is a gear device comprising an internal gear 2 and planetary gears 3. In this gear device 1, the planetary gears 3 are arranged inside the annular internal gear 2, and by oscillating the planetary gears 3, the planetary gears 3 are rotated relative to the internal gear 2. The internally meshing planetary gear device 1 also comprises a bearing member 6 having an outer ring 62 and an inner ring 61. The inner ring 61 is arranged inside the outer ring 62 and is supported so as to be rotatable relative to the outer ring 62. In particular, the gear device 1 according to this basic configuration is an eccentric oscillating type internally meshing planetary gear device known as a distribution type.

[0015] As shown in FIGS. 1 to 4, the gear device 1 according to this basic configuration includes multiple (three in the basic configuration) crankshafts (eccentric shafts) 7A, 7B, and 7C arranged at positions offset from the axis (rotation axis Ax1) of the internal gear 2. The gear device 1 also includes an input shaft 500 centered on the axis (rotation axis Ax1) of the internal gear 2, and an input gear 501 formed integrally with the input shaft 500. Crankshaft gears 502A, 502B, and 502C are spline-connected to the multiple crankshafts 7A, 7B, and 7C, respectively. These multiple (three in the basic configuration) crankshaft gears 502A, 502B, and 502C are arranged to mesh with the input gear 501. Therefore, when the input shaft 500 of the gear device 1 is driven, the input gear 501 drives the crankshafts 7A, 7B, and 7C in synchronization with each other, thereby causing the planetary gear 3 to oscillate.

[0016] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. In particular, in this basic configuration, the internal gear 2 has an annular gear body 22 and multiple outer pins 23. The multiple outer pins 23 are rotatably held on the inner circumferential surface 221 of the gear body 22 and form the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. In other words, the planetary gear 3 is inscribed inside the internal gear 2, and some of the external teeth 31 mesh with some of the internal teeth 21. In this state, when the multiple crankshafts 7A, 7B, and 7C are driven, the planetary gear 3 oscillates, and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). If the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in accordance with the relative rotation of the two gears. As a result, the planetary gear 3 produces a rotational output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

[0017] This type of gear device 1 is used so that rotation equivalent to the rotation component of the planetary gear 3 is extracted as rotation of a pair of carriers 18, 19 that are integrated with the inner ring 61 of the bearing member 6. As a result, the gear device 1 functions as a gear device with a relatively high reduction ratio, with the input shaft 500 as the input side and the pair of carriers 18, 19 as the output side. Therefore, in the gear device 1 according to this basic configuration, the pair of carriers 18, 19 supports multiple crankshafts 7A, 7B, 7C so that rotation equivalent to the rotation component of the planetary gear 3 can be transmitted to the pair of carriers 18, 19. The pair of carriers 18, 19 are disposed on both sides of the planetary gear 3 in the axial direction (the direction along the rotation axis Ax1) and rotatably support the crankshafts 7A, 7B, 7C.

[0018] Here, the multiple crankshafts 7A, 7B, and 7C are inserted into multiple openings 33 formed in the planetary gear 3, respectively, and rotate relative to the internal gear 2 in conjunction with the rotation of the planetary gear 3. Each of the crankshafts 7A, 7B, and 7C has an axial portion 71 and an eccentric portion 72 that is eccentric with respect to the axial portion 71. A pair of carriers 18 and 19 rotatably support the axial portions 71 of the crankshafts 7A, 7B, and 7C, and the eccentric portions 72 of the crankshafts 7A, 7B, and 7C are inserted into the openings 33 of the planetary gear 3. Therefore, the oscillation component of the planetary gear 3, i.e., the orbital component of the planetary gear 3, is absorbed by the orbital component of the eccentric portion 72 with respect to the axial portion 71. In other words, the eccentric portions 72 of the axial portions 71 of the crankshafts 7A, 7B, 7C rotate so as to revolve around the axial portions 71, thereby absorbing the oscillation component of the planetary gears 3. Therefore, the rotation (rotation component) of the planetary gears 3, excluding the oscillation component (revolution component) of the planetary gears 3, is transmitted to the pair of carriers 18, 19 by the multiple crankshafts 7A, 7B, 7C.

[0019] 1, the gear device 1 according to this basic configuration, together with a drive source 101, constitutes an actuator 100. In other words, the actuator 100 according to this basic configuration includes the gear device 1 and the drive source 101. The drive source 101 generates a drive force for oscillating the planetary gear 3. Specifically, the drive source 101 rotates the input shaft 500 about the rotation axis Ax1, thereby oscillating the planetary gear 3.

[0020] (2) Definition In the present disclosure, "annular" refers to a ring-like shape that forms an enclosed space (region) at least in a plan view, and is not limited to a circular shape (annular ring) such as a perfect circle in a plan view, but may also be, for example, an elliptical shape, a polygonal shape, etc. Furthermore, even if a shape has a bottom, such as a cup-like shape, it is included in the "annular" category as long as the peripheral wall is annular.

[0021] In this disclosure, "revolution" means that an object revolves around an axis of rotation other than the central axis passing through the center (center of gravity) of the object. When an object revolves, the center of the object moves along an orbital path centered on the axis of rotation. Therefore, for example, when an object rotates around an eccentric axis parallel to the central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric axis as the axis of rotation. As an example, the planetary gear 3 revolves within the internal gear 2 by oscillating, so as to revolve around the rotation axis Ax1.

[0022] In addition, in the present disclosure, one side of the rotation axis Ax1 (the left side in FIG. 4) may be referred to as the "output side," and the other side of the rotation axis Ax1 (the right side in FIG. 4) may be referred to as the "input side." In the example of FIG. 4, rotation is imparted to the input shaft 500 from the "input side" of the rotation axis Ax1, and rotation of the pair of carriers 18, 19 is extracted from the "output side" of the rotation axis Ax1. However, the terms "input side" and "output side" are merely labels used for the purpose of explanation and are not intended to limit the positional relationship between the input and output from the perspective of the gear device 1.

[0023] In this disclosure, the term "rotation axis" refers to a virtual axis (straight line) that is the center of rotational motion of a rotating body. In other words, the rotation axis Ax1 is a virtual axis that does not have a physical entity. The input shaft 500 performs rotational motion around the rotation axis Ax1.

[0024] In this disclosure, "internal teeth" and "external teeth" do not refer to a single "tooth," but rather to a set (group) of multiple "teeth." In other words, the internal teeth 21 of the internal gear 2 are made up of a set of multiple teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 are made up of a set of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

[0025] (3) Composition The detailed configuration of the internal meshing planetary gear device 1 according to this basic configuration will be described below with reference to FIGS.

[0026] FIG. 1 is a perspective view showing the general configuration of an actuator 100 including a gear device 1. FIG. 1 schematically shows a drive source 101. FIG. 2 is a general exploded perspective view of the gear device 1 as seen from the input side of the rotation axis Ax1. FIG. 3 is a general exploded perspective view of the gear device 1 as seen from the output side of the rotation axis Ax1. FIG. 4 is a general cross-sectional view of the gear device 1. FIG. 5 is a cross-sectional view taken along line A1-A1 in FIG. 4. FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 4. However, in FIGS. 5 and 6, hatching is omitted for parts other than crankshafts 7A, 7B, and 7C, even in cross sections.

[0027] (3.1) Overall structure As shown in FIGS. 1 to 4 , a gear device 1 according to this basic configuration includes an internal gear 2, a planetary gear 3, a bearing member 6, multiple crankshafts 7A, 7B, and 7C, a pair of carriers 18 and 19, and an input shaft 500. In this basic configuration, the gear device 1 further includes an input gear 501, multiple crankshaft gears 502A, 502B, and 502C, a pair of rolling bearings 41 and 42, an eccentric bearing 5, and a case 10. In this basic configuration, the components of the gear device 1, such as the internal gear 2, the planetary gear 3, the multiple crankshafts 7A, 7B, and 7C, and the pair of carriers 18 and 19, are made of metals such as stainless steel, cast iron, carbon steel for machine structures, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. Here, metals (including light metals) include metals that have been subjected to surface treatments such as nitriding.

[0028] In addition, in this basic configuration, an internal planetary gear device using a trochoidal tooth profile is exemplified as an example of the gear device 1. In other words, the gear device 1 according to this basic configuration includes an internal planetary gear 3 having a trochoidal curved tooth profile.

[0029] In addition, in this basic configuration, as an example, the gear device 1 is used with the gear body 22 of the internal gear 2, together with the outer ring 62 of the bearing member 6, fixed to a fixed member such as the case 10. As a result, as the internal gear 2 and the planetary gear 3 rotate relative to each other, the planetary gear 3 rotates relative to the fixed member (such as the case 10).

[0030] Furthermore, in this basic configuration, when the gear device 1 is used in the actuator 100, a rotational force is applied as an input to the input shaft 500, and a rotational force is extracted as an output from the pair of carriers 18, 19 integrated with the inner ring 61 of the bearing member 6. In other words, the gear device 1 operates with the rotation of the input shaft 500 as the input rotation and the rotation of the pair of carriers 18, 19 integrated with the inner ring 61 as the output rotation. As a result, the gear device 1 can obtain an output rotation that is reduced in speed by a relatively high reduction ratio relative to the input rotation.

[0031] The driving source 101 is a power generating source such as a motor (electric motor). The power generated by the driving source 101 is transmitted to an input shaft 500 in the gear device 1. Specifically, the driving source 101 is connected to the input shaft 500, and the power generated by the driving source 101 is transmitted to the input shaft 500. This enables the driving source 101 to rotate the input shaft 500.

[0032] Furthermore, in the gear device 1 according to this basic configuration, as shown in FIG. 4, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are on the same straight line. In other words, the input-side rotation axis Ax1 and the output-side rotation axis Ax1 are coaxial. Here, the input-side rotation axis Ax1 is the rotation center of the input shaft 500 to which the input rotation is applied, and the output-side rotation axis Ax1 is the rotation center of the inner ring 61 (and the pair of carriers 18, 19) that generates the output rotation. In other words, in the gear device 1, output rotation is obtained that is reduced in speed at a relatively high reduction ratio relative to the input rotation on the same axis.

[0033] As shown in Figures 5 and 6, the internal gear 2 is an annular component having internal teeth 21. In this basic configuration, the internal gear 2 has an annular shape, with at least the inner circumferential surface being a perfect circle in a plan view. The internal teeth 21 are formed on the inner circumferential surface of the annular internal gear 2 along the circumferential direction of the internal gear 2. The multiple teeth that make up the internal teeth 21 all have the same shape and are arranged at equal pitches over the entire circumferential area of the inner circumferential surface of the internal gear 2. In other words, the pitch circle of the internal teeth 21 is a perfect circle in a plan view. The center of the pitch circle of the internal teeth 21 is on the rotation axis Ax1. The internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. The tooth traces of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth trace direction is slightly smaller than the dimension in the thickness direction of the internal gear 2.

[0034] As described above, the internal gear 2 has an annular (circular) gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are rotatably held on the inner circumferential surface 221 of the gear body 22 and form the internal teeth 21. In other words, the plurality of outer pins 23 function as a plurality of teeth that form the internal teeth 21. Specifically, as shown in FIG. 2 , a plurality of inner circumferential grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over the entire circumferential area. All of the inner circumferential grooves 223 have the same shape and are arranged at equal pitches. All of the inner circumferential grooves 223 are parallel to the rotation axis Ax1 and are formed over the entire length of the gear body 22 in the thickness direction. The plurality of outer pins 23 are fitted into the plurality of inner circumferential grooves 223 and are combined with the gear body 22. Each of the plurality of outer pins 23 is rotatably held within the inner circumferential groove 223. The gear body 22 is fixed (together with the outer ring 62) to the case 10. Furthermore, the gear body 22 is formed with a plurality of fixing holes 222 (see FIG. 5) for fixing.

[0035] As shown in FIGS. 5 and 6 , the planetary gear 3 is an annular component having external teeth 31. In this basic configuration, the planetary gear 3 has an annular shape, with at least the outer circumferential surface being a perfect circle in a plan view. The outer circumferential surface of the annular planetary gear 3 is formed with external teeth 31 along the circumferential direction of the planetary gear 3. The multiple teeth constituting the external teeth 31 all have the same shape and are provided at equal pitches over the entire circumferential area of the outer circumferential surface of the planetary gear 3. In other words, the pitch circle of the external teeth 31 is a perfect circle in a plan view. The planetary gear 3 also has a predetermined thickness in the direction of the rotation axis Ax1. All of the external teeth 31 are formed over the entire length of the planetary gear 3 in the thickness direction. The tooth traces of the external teeth 31 are all parallel to the rotation axis Ax1. Unlike the internal gear 2, the planetary gear 3 has the external teeth 31 formed integrally with the main body of the planetary gear 3 using a single metal member.

[0036] The gear device 1 according to this basic configuration also includes a plurality of planetary gears 3. Specifically, the gear device 1 includes two planetary gears 3: a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged to face each other in a direction parallel to the rotation axis Ax1. In other words, the planetary gears 3 include the first planetary gear 301 and the second planetary gear 302 that are aligned in a direction parallel to the rotation axis Ax1 (axial direction). The first planetary gear 301 and the second planetary gear 302 have the same shape.

[0037] These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged with a phase difference of 180 degrees around the rotation axis Ax1. In the example of FIG. 4, of the first planetary gear 301 and the second planetary gear 302, the center C1 (center of the pitch circle of the external teeth 31) of the first planetary gear 301 located on the input side of the rotation axis Ax1 (right side in FIG. 4) is shifted (biased) upward in the figure with respect to the rotation axis Ax1. On the other hand, the center C2 (center of the pitch circle of the external teeth 31) of the second planetary gear 302 located on the output side of the rotation axis Ax1 (left side in FIG. 4) is shifted (biased) downward in the figure with respect to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the amount of eccentricity of the first planetary gear 301 relative to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 is the amount of eccentricity of the second planetary gear 302 relative to the rotation axis Ax1. In this way, by arranging the multiple planetary gears 3 evenly in the circumferential direction around the rotation axis Ax1, it is possible to balance the weight and load among the multiple planetary gears 3.

[0038] The centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are located at 180-degree rotational symmetry with respect to the rotation axis Ax1. In this basic configuration, the eccentricity ΔL1 and the eccentricity ΔL2 are oriented in opposite directions when viewed from the rotation axis Ax1, but their absolute values are the same.

[0039] More specifically, each of the crankshafts 7A, 7B, and 7C has two eccentric portions 72 with respect to one axial portion 71. The eccentricity ΔL0 (see FIGS. 5 and 6) of the center C0 of these two eccentric portions 72 from the center (axial center Ax2) of the axial portion 71 is the same as the eccentricity ΔL1 and ΔL2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation axis Ax1, respectively. The multiple crankshafts 7A, 7B, and 7C have a common shape. The multiple crankshaft gears 502A, 502B, and 502C also have a common shape.

[0040] A pair of carriers 18, 19 are disposed on both sides of the first planetary gear 301 and the second planetary gear 302 in the direction parallel to the rotation axis Ax1 (axial direction). When distinguishing between the pair of carriers 18, 19, the carrier 18 located on the input side of the rotation axis Ax1 (right side in FIG. 4) is referred to as the "input side carrier 18," and the carrier 19 located on the output side of the rotation axis Ax1 (left side in FIG. 4) is referred to as the "output side carrier 19." Both ends of each crankshaft 7A, 7B, 7C are held by the pair of carriers 18, 19 via rolling bearings 41, 42. In other words, each crankshaft 7A, 7B, 7C is held by the input side carrier 18 and the output side carrier 19 on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax1 (axial direction) in a rotatable state.

[0041] An eccentric body bearing 5 is attached to the eccentric portion 72 of each of the crankshafts 7A, 7B, and 7C. Three openings 33 corresponding to the three crankshafts 7A, 7B, and 7C are formed in each of the first planetary gear 301 and the second planetary gear 302. An eccentric body bearing 5 is housed in each of the openings 33. In other words, the first planetary gear 301 and the second planetary gear 302 are each fitted with an eccentric body bearing 5, and the crankshafts 7A, 7B, and 7C are inserted into the eccentric body bearings 5, thereby combining the eccentric body bearings 5 and the crankshafts 7A, 7B, and 7C with the planetary gear 3. When the crankshafts 7A, 7B, and 7C rotate with the eccentric body bearings 5 and the crankshafts 7A, 7B, and 7C combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0042] According to the configuration described above, when a rotational force is applied as an input to the input shaft 500 and the input shaft 500 rotates about the rotation axis Ax1, the rotational force is distributed from the input gear 501 to the multiple crankshafts 7A, 7B, and 7C. In other words, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that are simultaneously meshed with the input gear 501 rotate in the same direction at the same rotational speed. Because the crankshafts 7A, 7B, and 7C are spline-connected to the crankshaft gears 502A, 502B, and 502C, the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same rotational speed, reduced in speed by the gear ratio between the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, the three eccentric portions 72 formed at the same position on the input side of the rotation axis Ax1 on the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the first planetary gear 301 to oscillate. Furthermore, the three eccentric portions 72 formed at the same position on the output side of the rotation axis Ax1 on the three crankshafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to oscillate.

[0043] 5 and 6 show the states of the first planetary gear 301 and the second planetary gear 302 at a certain point in time. FIG. 5 is a cross-sectional view taken along line A1-A1 in FIG. 4, showing the first planetary gear 301. FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 4, showing the second planetary gear 302. As shown in FIGS. 5 and 6, the centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are positioned at approximately 180 degrees rotational symmetry with respect to the rotation axis Ax1. In this basic configuration, the eccentricity ΔL1 and the eccentricity ΔL2 are oriented in opposite directions when viewed from the rotation axis Ax1, but their absolute values are approximately the same (both are the eccentricity ΔL0). According to the above-described configuration, the shaft center portion 71 rotates (spins) around the axis Ax2, causing the first planetary gear 301 and the second planetary gear 302 to rotate (execute eccentric motion) around the rotation axis Ax1 with a phase difference of approximately 180 degrees around the rotation axis Ax1. Furthermore, by arranging the multiple planetary gears 3 approximately evenly in the circumferential direction around the rotation axis Ax1, it is possible to balance the weight and load among the multiple planetary gears 3.

[0044] The planetary gear 3 (first planetary gear 301 and second planetary gear 302) configured in this manner is disposed inside the internal gear 2. In a plan view, the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 is able to oscillate inside the internal gear 2 when combined with the internal gear 2. Here, external teeth 31 are formed on the outer peripheral surface of the planetary gear 3, and internal teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gear 3 is disposed inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

[0045] Furthermore, the pitch circle of the external teeth 31 is slightly smaller than the pitch circle of the internal teeth 21. When the first planetary gear 301 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 of the first planetary gear 301 is shifted by a distance ΔL1 from the center of the pitch circle of the internal teeth 21 (the rotation axis Ax1). Similarly, when the second planetary gear 302 is inscribed in the internal gear 2, the center C2 of the pitch circle of the external teeth 31 of the second planetary gear 302 is shifted by a distance ΔL2 from the center of the pitch circle of the internal teeth 21 (the rotation axis Ax1).

[0046] Therefore, in both the first planetary gear 301 and the second planetary gear 302, the external teeth 31 and the internal teeth 21 at least partially face each other with a gap therebetween, and if the difference in the number of teeth between the external teeth 31 and the internal teeth 21 is two or more, they do not mesh with each other over the entire circumferential direction. However, since the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, the external teeth 31 and the internal teeth 21 partially mesh with each other. In other words, as the planetary gears 3 (first planetary gear 301 and second planetary gear 302) oscillate around the rotation axis Ax1, some of the multiple teeth that make up the external teeth 31 mesh with some of the multiple teeth that make up the internal teeth 21, as shown in FIGS. 5 and 6 . As a result, in the gear device 1, it is possible to mesh some of the external teeth 31 with some of the internal teeth 21.

[0047] Here, the number of teeth of the internal teeth 21 of the internal gear 2 is N (N is a positive integer) more than the number of teeth of the external teeth 31 of the planetary gear 3. In this basic configuration, as an example, N is "2", and the number of teeth (of the external teeth 31) of the planetary gear 3 is "2" less than the number of teeth (of the internal teeth 21) of the internal gear 2. This difference in the number of teeth between the planetary gear 3 and the internal gear 2 determines the reduction ratio of the output rotation to the input rotation in the gear device 1.

[0048] In addition, in this basic configuration, as an example, the combined thickness of the first planetary gear 301 and the second planetary gear 302 is smaller than the thickness of the gear body 22 of the internal gear 2. Furthermore, the dimension in the tooth trace direction (direction parallel to the rotation axis Ax1) of the combined external teeth 31 of the first planetary gear 301 and the second planetary gear 302 is smaller than the dimension in the tooth trace direction (direction parallel to the rotation axis Ax1) of the internal teeth 21. In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 of the first planetary gear 301 and the second planetary gear 302 are contained within the range of the tooth trace of the internal teeth 21.

[0049] Here, the first planetary gear 301 and the second planetary gear 302 are internally meshed with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 oscillate once, a phase shift in the circumferential direction occurs in the first planetary gear 301 and the second planetary gear 302 relative to the internal gear 2 by the difference in the number of teeth (between the internal teeth 21 and the external teeth 31), causing the first planetary gear 301 and the second planetary gear 302 to rotate. This rotation is transmitted to the pair of carriers 18 and 19 as revolutions around the axis (rotation axis Ax1) of the internal gear 2 of each crankshaft 7A, 7B, and 7C. This allows the pair of carriers 18 and 19 to rotate relative to the gear main body (case 10 integrated therewith) about the rotation axis Ax1.

[0050] In short, the gear device 1 according to this basic configuration oscillates the planetary gear 3 using multiple crankshafts 7A, 7B, and 7C that are positioned offset from the rotation axis Ax1, and generates rotational output using the oscillation of the planetary gear 3. In other words, in the gear device 1, when the planetary gear 3 oscillates and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, a relative rotation occurs between the two gears (the internal gear 2 and the planetary gear 3) according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (spins) in accordance with the relative rotation between the two gears. As a result, the planetary gear 3 generates a rotational output that is reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears.

[0051] The bearing member 6 has an outer ring 62 and an inner ring 61, and is a component for extracting the output of the gear device 1 as rotation of the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and the inner ring 61, the bearing member 6 also has a plurality of rolling elements 63 (see FIG. 4). The outer ring 62 and the inner ring 61 are both annular components. The outer ring 62 and the inner ring 61 both have an annular shape that is a perfect circle in a plan view. The inner ring 61 is one size smaller than the outer ring 62 and is disposed inside the outer ring 62. Here, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, so a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61.

[0052] The plurality of rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61. The plurality of rolling elements 63 are arranged side by side in the circumferential direction of the outer ring 62. The plurality of rolling elements 63 are all metal parts of the same shape, and are provided at equal pitches over the entire circumferential area of the outer ring 62.

[0053] More specifically, in the gear device 1 according to this basic configuration, the bearing member 6 includes a first bearing member 601 and a second bearing member 602. The first bearing member 601 and the second bearing member 602 are each made up of an angular contact ball bearing. Specifically, as shown in FIG. 4, the first bearing member 601 is disposed on the input side (right side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3, and the second bearing member 602 is disposed on the output side (left side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3. The bearing member 6 is configured so that the first bearing member 601 and the second bearing member 602 can withstand a radial load, a thrust load (direction along the rotation axis Ax1), and a bending force (bending moment load) against the rotation axis Ax1.

[0054] Here, the first bearing member 601 and the second bearing member 602 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1 (axial direction), facing opposite to each other in the direction parallel to the rotation axis Ax1. In other words, the bearing member 6 is a "duplex angular contact ball bearing" that combines multiple (here, two) angular contact ball bearings. As an example, the first bearing member 601 and the second bearing member 602 are of a "back-to-back combination type" that receives a load in the thrust direction (direction along the rotation axis Ax1) in which the respective inner rings 61 move toward each other. Furthermore, in the gear device 1, the first bearing member 601 and the second bearing member 602 are combined in a state in which an appropriate preload acts on the inner rings 61 by tightening the respective inner rings 61 in a direction in which they move toward each other.

[0055] In the gear device 1 according to this basic configuration, the input carrier 18 and the output carrier 19 are disposed on either side of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and are coupled to each other through the carrier holes 34 of the planetary gear 3 (see FIG. 4). Specifically, as shown in FIG. 4, the input carrier 18 is disposed on the input side (right side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3, and the output carrier 19 is disposed on the output side (left side in FIG. 4) of the rotation axis Ax1 as viewed from the planetary gear 3. The inner rings 61 of the bearing members 6 (each of the first bearing member 601 and the second bearing member 602) are fixed to the input carrier 18 and the output carrier 19. In this basic configuration, as an example, the inner ring of the first bearing member 601 is seamlessly integrated with the input carrier 18. Similarly, the inner ring of the second bearing member 602 is seamlessly integrated with the output carrier 19.

[0056] The output-side carrier 19 has a plurality of (three, for example) carrier pins 191 (see FIG. 2) that protrude from one surface of the output-side carrier 19 toward the input side of the rotation axis Ax1. These carrier pins 191 respectively pass through a plurality of (three, for example) carrier holes 34 formed in the planetary gear 3, and their tips are fixed to the input-side carrier 18 by carrier bolts 192 (see FIG. 7). A gap is secured between the carrier pins 191 and the inner circumferential surface of the carrier hole 34, and the carrier pins 191 are movable within the carrier hole 34, that is, movable relative to the center of the carrier hole 34. This prevents the carrier pins 191 from coming into contact with the inner circumferential surface of the carrier hole 34 when the planetary gear 3 oscillates.

[0057] With the above configuration, the gear device 1 is used so that rotation equivalent to the rotation component of the planetary gear 3 is extracted as rotation of the input side carrier 18 and the output side carrier 19 that are integrated with the inner ring 61 of the bearing member 6. That is, in this basic configuration, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the input side carrier 18 and the output side carrier 19. In this basic configuration, as an example, the gear device 1 is used with the outer ring 62 of the bearing member 6 (see FIG. 4) fixed to the case 10, which is a fixed member. That is, the planetary gear 3 is connected to the input side carrier 18 and the output side carrier 19, which are rotating members, by multiple crankshafts 7A, 7B, and 7C, and the gear main body 22 is fixed to a fixed member, so that the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the rotating members (the input side carrier 18 and the output side carrier 19). In other words, in this basic configuration, when the planetary gear 3 rotates relative to the gear body 22, the rotational forces of the input side carrier 18 and the output side carrier 19 are extracted as outputs.

[0058] Furthermore, in this basic configuration, the case 10 is seamlessly integrated with the gear body 22 of the internal gear 2. In other words, the gear body 22, which is a fixed member, and the case 10 are provided in a seamless continuity in the direction parallel to the rotation axis Ax1.

[0059] More specifically, the case 10 is cylindrical and forms the outer shell of the gear device 1. In this basic configuration, the central axis of the cylindrical case 10 is configured to coincide with the rotation axis Ax1. That is, at least the outer peripheral surface of the case 10 is a perfect circle centered on the rotation axis Ax1 in a plan view (seen from one axial direction). The case 10 is formed into a cylindrical shape with both axial end faces open. The gear body 22 of the internal gear 2 is seamlessly integrated with the case 10, and the case 10 and the gear body 22 are treated as a single component. Therefore, the inner peripheral surface of the case 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, the outer ring 62 of the bearing member 6 is fixed to the case 10. That is, the outer ring 62 of the first bearing member 601 is fitted and fixed to the inner peripheral surface of the case 10 on the input side of the rotation axis Ax1 (the right side in FIG. 4 ) of the gear body 22. Meanwhile, an outer ring 62 of a second bearing member 602 is fitted and fixed to the inner circumferential surface of the case 10 on the output side (left side in FIG. 4) of the rotation axis Ax1 as viewed from the gear body 22.

[0060] Furthermore, the end face of the case 10 on the input side (right side in FIG. 4) of the rotation shaft Ax1 is closed by the input side carrier 18, and the end face of the case 10 on the output side (left side in FIG. 4) of the rotation shaft Ax1 is closed by the output side carrier 19. Therefore, as shown in FIG. 4, parts such as the planetary gear 3 (first planetary gear 301 and second planetary gear 302), the plurality of outer pins 23, and the eccentric bearing 5 are housed in the space surrounded by the case 10, the input side carrier 18, and the output side carrier 19.

[0061] Each of the multiple crankshafts 7A, 7B, and 7C (three in the basic configuration) has an axial portion 71 and two eccentric portions 72. The axial portion 71 has a cylindrical shape, with at least the outer circumferential surface being a perfect circle in a plan view. An axial center Ax2, which is the center of the axial portion 71, is parallel to the rotational axis Ax1. The axial centers Ax2 of the multiple crankshafts 7A, 7B, and 7C are arranged at equal intervals in the circumferential direction on a virtual circle centered on the rotational axis Ax1. Each eccentric portion 72 has a disk shape, with at least the outer circumferential surface being a perfect circle in a plan view. The center (center axis) C0 of each eccentric portion 72 is parallel to the rotational axis Ax1 and is positioned radially offset from the rotational axis Ax1. Here, the distance ΔL0 between the axial center Ax2 and the center C0 (see FIGS. 5 and 6) is the eccentricity of the eccentric portion 72 with respect to the axial portion 71. The eccentric portion 72 has a flange shape that protrudes from the outer circumferential surface of the axial portion 71 at the center in the longitudinal direction (axial direction) of the axial portion 71 over the entire circumference. According to the above-described configuration, the axial portion 71 of each of the crankshafts 7A, 7B, 7C rotates (spins) about the axis Ax2, causing the eccentric portion 72 to perform eccentric motion.

[0062] In this basic configuration, the axial portion 71 and the two eccentric portions 72 are integrally formed from a single metal member, thereby realizing seamless crankshafts 7A, 7B, and 7C. The crankshafts 7A, 7B, and 7C having such a shape are combined with the planetary gear 3 together with the eccentric bearing 5. Therefore, when the crankshafts 7A, 7B, and 7C rotate in a state where the eccentric bearing 5 and the crankshafts 7A, 7B, and 7C are combined with the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0063] The eccentric body bearing 5 has a plurality of rolling elements 51 (see FIG. 4 ) and is a component that absorbs the rotational component of the rotation of the crankshafts 7A, 7B, 7C and transmits only the rotation of the crankshafts 7A, 7B, 7C excluding the rotational component of the crankshafts 7A, 7B, 7C, i.e., only the oscillation component (revolution component) of the crankshafts 7A, 7B, 7C, to the planetary gear 3. The plurality of rolling elements 51 are disposed between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, 7C and the inner peripheral surface of each opening 33 of the planetary gear 3. In other words, the eccentric portion 72 of each crankshaft 7A, 7B, 7C functions as the inner ring of the eccentric body bearing 5, and the inner peripheral surface of each opening 33 of the planetary gear 3 functions as the outer ring of the eccentric body bearing 5.

[0064] When the eccentric bearing 5 and the multiple crankshafts 7A, 7B, and 7C are combined with the planetary gear 3 and the crankshafts 7A, 7B, and 7C rotate, the eccentric bearing 5 rotates (eccentrically moves) around the axis Ax2. At this time, the rotational components of the crankshafts 7A, 7B, and 7C are absorbed by the eccentric bearing 5. Therefore, only the rotation of the crankshafts 7A, 7B, and 7C, excluding the rotational components of the crankshafts 7A, 7B, and 7C, i.e., only the oscillation components (revolution components) of the crankshafts 7A, 7B, and 7C, are transmitted to the planetary gear 3 by the eccentric bearing 5. Therefore, when the crankshafts 7A, 7B, and 7C rotate with the eccentric bearing 5 and the crankshafts 7A, 7B, and 7C combined with the planetary gear 3, the planetary gear 3 oscillates around the rotational axis Ax1.

[0065] In the gear device 1 configured as described above, a rotational force is applied as an input to the input shaft 500, causing the input shaft 500 to rotate about the rotation axis Ax1, causing the planetary gear 3 to oscillate (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 is inscribed with the internal gear 2 inside the internal gear 2 and oscillates with some of the external teeth 31 meshing with some of the internal teeth 21, so that the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. As a result, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). The rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the pair of carriers 18 and 19 by the multiple crankshafts 7A, 7B, and 7C. As a result, a rotation output is obtained from the pair of carriers 18, 19, which is reduced in speed at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

[0066] In the gear device 1 according to this basic configuration, as described above, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 determines the reduction ratio of the output rotation to the input rotation in the gear device 1. In other words, if the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2," the reduction ratio R1 is expressed by the following formula 1.

[0067] R1=V2 / (V1-V2) (Equation 1) In other words, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3, the larger the reduction ratio R1. As an example, the number of teeth V1 of the internal gear 2 is 72, the number of teeth V2 of the planetary gear 3 is 70, and the difference in the number of teeth (V1-V2) is 2. Therefore, according to the above formula 1, the reduction ratio R1 is 35. In this case, when viewed from the input side of the rotation axis Ax1, when each of the crankshafts 7A, 7B, and 7C rotates clockwise one revolution (360 degrees) around the axis Ax2 of the shaft center 71 (see FIGS. 5 and 6), the pair of carriers 18 and 19 rotate counterclockwise around the rotation axis Ax1 by the amount of the difference in the number of teeth of 2 (i.e., approximately 10.3 degrees).

[0068] According to the gear device 1 of this basic configuration, such a high reduction ratio R1 can be achieved by combining the internal gear 2 and the planetary gears 3. Furthermore, an appropriate reduction ratio can be achieved between the input gear 501 and the multiple crankshaft gears 502A, 502B, 502C depending on the number of teeth of the input gear 501 and the crankshaft gears 502A, 502B, 502C. As a result, the gear device 1 as a whole can achieve a high reduction ratio.

[0069] The gear device 1 only needs to include at least the internal gear 2, the planetary gear 3, the crankshafts 7A, 7B, and 7C, and a pair of carriers 18 and 19, and may further include a spacer 11, for example, as shown in Fig. 4. The spacer 11 is disposed between the pair of planetary gears 3 (first planetary gear 301 and second planetary gear 302) in a direction parallel to the rotation axis Ax1 (axial direction).

[0070] (Embodiment 1) As shown in FIGS. 7 to 9, the internal meshing planetary gear device 1A according to this embodiment (hereinafter also simply referred to as "gear device 1A") differs from the gear device 1 according to the basic configuration mainly in the configuration of the planetary gears 3 (first planetary gears 301 and second planetary gears 302). Hereinafter, components similar to those in the basic configuration will be assigned the same reference numerals and explanations thereof will be omitted as appropriate. FIG. 7 is a schematic cross-sectional view of the gear device 1A. FIG. 8 is a schematic cross-sectional view showing only the planetary gears 3 (first planetary gears 301 and second planetary gears 302) of the gear device 1A, with an enlarged view of the main parts shown in the balloons. FIG. 9 is a schematic view of the internal gear 2 and planetary gears 3 as viewed from the input side of the rotation axis Ax1 (the right side in FIG. 7).

[0071] As shown in FIG. 7 , the gear device 1A according to this embodiment further includes a plurality of oil seals 121, 122, etc. The oil seal 121 seals the gap between the case 10 and the outer peripheral surface of the output side carrier 19. The oil seal 122 seals a central hole 193 formed in the center of the output side carrier 19. The space sealed by these plurality of oil seals 121, 122, etc. constitutes a lubricant retention space 17. The lubricant retention space 17 includes the space between the inner ring 61 and the outer ring 62 of the bearing member 6. Furthermore, the lubricant retention space 17 accommodates a plurality of outer pins 23, a planetary gear 3, a pair of rolling bearings 41, 42, an eccentric bearing 5, etc.

[0072] The lubricant retention space 17 is filled with a lubricant. The lubricant is liquid and can flow within the lubricant retention space 17. Therefore, when the gear device 1 is in use, the lubricant enters, for example, the meshing portion between the internal teeth 21 consisting of the multiple outer pins 23 and the external teeth 31 of the planetary gear 3. In this disclosure, "liquid" includes liquid and gel-like substances. "Gel-like" here refers to a state having properties intermediate between liquid and solid, including a colloidal state consisting of two phases: liquid and solid. For example, "gel-like" includes gel or sol states such as emulsions in which the dispersion medium is liquid and the dispersoid is liquid, and suspensions in which the dispersoid is solid. Furthermore, "gel-like" also includes a state in which the dispersion medium is solid and the dispersoid is liquid. In this basic configuration, as an example, the lubricant is liquid lubricating oil.

[0073] The gear device 1A according to this embodiment further includes a pair of covers 13, 14 attached to both axial sides of the pair of carriers 18, 19. When distinguishing between the pair of covers 13, 14, the cover 13 located on the input side of the rotating shaft Ax1 (the right side in FIG. 7) will be referred to as the "input side cover 13," and the cover 14 located on the output side of the rotating shaft Ax1 (the left side in FIG. 7) will be referred to as the "output side cover 14." In this embodiment, the pair of covers 13, 14 are made of a metal such as stainless steel, cast iron, carbon steel for mechanical construction, or chromium-molybdenum steel, or a heat-treated metal thereof.

[0074] The input side cover 13 is formed in a disk shape centered on the rotation axis Ax1. Here, at least the outer peripheral surface of the input side cover 13 is a perfect circle centered on the rotation axis Ax1 in a plan view (seen from one axial direction). The outer diameter of the input side cover 13 is slightly smaller than the outer diameter of the input side carrier 18. The input side cover 13 is attached to the input side carrier 18 from the outside, that is, from the opposite side to the planetary gear 3 as seen from the input side carrier 18 (the right side in FIG. 7).

[0075] The output side cover 14 is formed in a disk shape centered on the rotation axis Ax1. Here, at least the outer peripheral surface of the output side cover 14 is a perfect circle centered on the rotation axis Ax1 in a plan view (seen from one axial direction). The outer diameter of the output side cover 14 is slightly smaller than the outer diameter of the output side carrier 19. The output side cover 14 is attached to the output side carrier 19 from the outside, that is, from the opposite side of the planetary gear 3 as seen from the output side carrier 19 (the left side in FIG. 7).

[0076] Here, the pair of covers 13, 14 are removably attached to the pair of carriers 18, 19. That is, the input side cover 13 is removably attached to the input side carrier 18, and the output side cover 14 is removably attached to the output side carrier 19. In this embodiment, as an example, each cover 13, 14 is attached to each carrier 18, 19 by a plurality of fixing bolts 142 (see FIG. 7). Therefore, each cover 13, 14 can be removed from each carrier 18, 19 by removing the plurality of fixing bolts 142.

[0077] Here, the output side cover 14 of the pair of covers 13, 14 is provided with a plurality of through holes 141 aligned with a plurality of mounting holes 194 (see FIG. 7) provided in the output side carrier 19. That is, the output side carrier 19 is provided with a plurality of mounting holes 194 (internal threads) for fixing a mating member. Therefore, the output side cover 14 attached to the outside of the output side carrier 19 also has a plurality of through holes 141 formed at positions corresponding to the plurality of mounting holes 194.

[0078] On the other hand, shaft holes 131 (see FIG. 7) through which the crankshafts 7A, 7B, and 7C pass are provided only in the input-side cover 13 of the pair of covers 13 and 14. That is, the input-side cover 13 is provided with a plurality of shaft holes 131 corresponding to the plurality of crankshafts 7A, 7B, and 7C. The shaft centers 71 of the crankshafts 7A, 7B, and 7C are inserted into each shaft hole 131. Here, the inner diameter of each shaft hole 131 is set to be slightly larger than the outer diameter of the shaft centers 71 so that the shaft centers 71 do not come into contact with the inner circumferential surface of the shaft hole 131.

[0079] In this embodiment, each of the multiple planetary gears 3 (first planetary gear 301 and second planetary gear 302) does not have a uniform axial thickness along the rotation axis Ax1, but is configured so that the external teeth 31 formed on the outer periphery are thicker than other portions. That is, the planetary gear 3 is configured so that the axial thickness of the external teeth 31 is greater than that of portions other than the external teeth 31. In other words, the planetary gear 3 has a circular recess in a central region surrounded by the external teeth 31 when viewed from the axial direction. Within this recess, the planetary gear 3 is formed with a center hole 32, multiple openings 33 into which the crankshafts 7A, 7B, and 7C are inserted, multiple carrier holes 34 for connecting the input side carrier 18 and the output side carrier 19, and the like.

[0080] Incidentally, when manufacturing a gear device 1A having a plurality of planetary gears 3 in this manner, it is preferable to simultaneously process the external teeth 31 of a plurality of stacked materials to manufacture the plurality of planetary gears 3. In other words, it is preferable that the external teeth 31 of the plurality of planetary gears 3 in the gear device 1A are not formed individually, but are formed by batch processing.

[0081] However, in order to process the external teeth 31 all at once, it is necessary to fix multiple planetary gears 3 (materials) in a stacked state. Therefore, if these multiple planetary gears 3 are fixed tightly so as not to shift, problems may arise, such as deformation of the planetary gears 3.

[0082] Therefore, in this embodiment, the configuration described below is used to realize gear components that are less likely to deform during processing of the external teeth 31, an internally meshing planetary gear device 1A, a robot joint device 200 (see Figure 11), and a method for manufacturing the internally meshing planetary gear device 1A.

[0083] That is, the gear component according to this embodiment is used in a gear device 1A as each of a plurality of planetary gears 3. The gear device 1A includes an internal gear 2 having internal teeth 21 and a plurality of planetary gears 3, each having external teeth 31 that partially mesh with the internal teeth 21. The gear device 1A rotates the plurality of planetary gears 3 relative to the internal gear 2 about the rotation axis Ax1 by oscillating the plurality of planetary gears 3. As shown in FIGS. 8 and 9, the gear component (planetary gear 3) has a boss portion 35 that protrudes from at least one surface in the axial direction along the rotation axis Ax1.

[0084] According to this configuration, by fastening the multiple gear components (planetary gears 3) using the boss portions 35, the multiple planetary gears 3 are firmly fixed to one another, while problems such as deformation of the planetary gears 3 are unlikely to occur. That is, each of the multiple gear components (planetary gears 3) is provided with a boss portion 35 protruding from at least one surface in the axial direction along the rotation axis Ax1. Therefore, for example, it is possible to fix the multiple planetary gears 3 (materials) in a stacked state so that the boss portions 35 abut against each other. As a result, when performing collective machining of the external teeth 31 and the like on the multiple gear components (planetary gears 3), even if the multiple planetary gears 3 are tightly fixed to prevent misalignment, problems such as deformation of the planetary gears 3 are unlikely to occur. As a result, it is possible to realize gear components (planetary gears 3) that are unlikely to deform during machining of the external teeth 31 and the like.

[0085] In this embodiment, the gear component (planetary gear 3) has a fastening hole 36 in the boss portion 35. The fastening hole 36 is a hole used when fastening multiple gear components (planetary gears 3) together. In this embodiment, as an example, as shown in FIG. 8, the fastening hole 36 is formed so as to penetrate the gear component (planetary gear 3) including the boss portion 35 in the axial direction along the rotation axis Ax1. This makes it possible to fasten multiple gear components (planetary gears 3) together by tightening fastening members such as a bolt Y1 (see FIG. 10) and a nut Y2 (see FIG. 10) through the fastening hole 36.

[0086] 8, the boss portion 35 is provided on the inner surface of each of the first planetary gear 301 and the second planetary gear 302, out of both surfaces in the axial direction along the rotation axis Ax1. That is, the boss portion 35 is provided on the surface of the first planetary gear 301 facing the second planetary gear 302, and the boss portion 35 is provided on the surface of the second planetary gear 302 facing the first planetary gear 301.

[0087] The tip end surface 351 of the boss portion 35 is located on the same plane as the end faces 311 of the external teeth 31. In other words, in each of the first planetary gear 301 and the second planetary gear 302, the amount of protrusion (height) of the boss portion 35 from one axial surface (the inner surface in this embodiment) is set to be the same as the amount of protrusion of the external teeth 31 from that surface. As a result, when multiple gear components (planetary gears 3) are stacked, the end faces 311 of the external teeth 31 come into contact with each other between these multiple gear components, and the tip end surfaces 351 of the boss portions 35 come into contact with each other between these multiple gear components. In other words, the boss portions 35 fill the gaps between the multiple gear components, so when the multiple gear components are fastened together, the boss portions 35 function as a spacer and make it easier to suppress deformation (warping) of each gear component.

[0088] In this embodiment, the fastening hole 36 is a through-hole that opens in a circular shape when viewed in the axial direction, as shown in Fig. 9. Therefore, the boss portion 35 is a cylindrical portion formed so that the fastening hole 36 passes through its center. The wall thickness of the boss portion 35 is set to a thickness sufficient to withstand the load when multiple gear components (planetary gears 3) are fastened together using fastening members such as bolts Y1 and nuts Y2. Furthermore, in this embodiment, the boss portion 35 is formed as a continuous, integrated unit with the gear components (planetary gears 3).

[0089] In this embodiment, each gear component (planetary gear 3) is provided with a plurality of boss portions 35 (for example, three boss portions 35), as shown in Fig. 9. Preferably, the plurality of boss portions 35 are arranged at equal intervals in the circumferential direction around the rotation axis Ax1.

[0090] Furthermore, each boss portion 35 is disposed at a position as far as possible from the center of the planetary gear 3, that is, at a position close to the outer periphery of the planetary gear 3 and at a position spaced apart from the external teeth 31 and the openings 33. Specifically, each boss portion 35 is disposed between the adjacent openings 33 and carrier holes 34 in the circumferential direction centered on the rotation axis Ax1.

[0091] Furthermore, when the gear device 1A is in operation, the multiple planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) oscillate, and the boss portion 35 also acts to stir the lubricant in the lubricant retention space 17. In other words, as the planetary gears 3 oscillate, the boss portion 35 moves within the lubricant retention space 17, and the lubricant in the lubricant retention space 17 is stirred by the boss portion 35, which also leads to improved lubrication performance.

[0092] FIG. 10 schematically shows a procedure for collectively machining a plurality of planetary gears 3 (first planetary gears 301 and second planetary gears 302) in the manufacturing method of the gear device 1A.

[0093] That is, when forming the external teeth 31, the openings 33, the carrier holes 34, etc., for the plurality of planetary gears 3, the plurality of planetary gears 3 are coupled (fastened) together as shown on the left side of Fig. 10. Specifically, the plurality of planetary gears 3 are fastened together by overlapping the plurality of planetary gears 3 and tightening fastening members such as bolts Y1 and nuts Y2 through the fastening holes 36.

[0094] In this way, if the plurality of planetary gears 3 are combined so as to be treated as a single component, it is possible to easily form, for example, the external teeth 31, the openings 33, the carrier holes 34, etc., all at once on the plurality of planetary gears 3. In other words, it is possible to perform processes such as tooth surface grinding or boring on the plurality of planetary gears 3 all at once, and it is possible to minimize variation in shape among the plurality of planetary gears 3.

[0095] In particular, by fastening multiple planetary gears 3 while aligning them with each other based on at least one of the center hole 32 and the opening 33 of the planetary gear 3, the multiple planetary gears 3 can be processed with their positions as closely matched as possible.

[0096] Furthermore, because it can be handled as a single component, it is easy to attach and detach the workpiece to and from the processing device (facility) during processing such as tooth surface grinding or boring, making it easier to handle automatic processing. Furthermore, compared to, for example, chucking the outer peripheries (external teeth 31) of multiple gear components (planetary gears 3) together, there is no need to consider phase shifts between multiple gear components, and it is only necessary to chuck one of the multiple gear components, making batch processing easier.

[0097] As described above, the manufacturing method of the gear device 1A according to this embodiment includes a batch processing step in which the planetary gears 3 are collectively processed while the planetary gears 3 are coupled together in the axial direction. This makes it possible to minimize variation in shape among the planetary gears 3.

[0098] Furthermore, in the collective machining process, the plurality of planetary gears 3 are fastened in the axial direction using the boss portions 35. This makes it possible to tightly fix the plurality of planetary gears 3 so that they do not shift, but this does not lead to problems such as deformation of the planetary gears 3. As a result, it is possible to achieve a manufacturing method for the gear device 1A in which deformation during machining of the external teeth 31, etc. is unlikely to occur.

[0099] As shown in FIG. 11 , the gear device 1A according to this embodiment, together with a first member 201 and a second member 202, constitutes a robot joint device 200. In other words, the robot joint device 200 according to this embodiment includes the gear device 1A, a first member 201, and a second member 202. The first member 201 is fixed to the internal gear 2. The second member 202 rotates relative to the first member 201 in accordance with the relative rotation of the planetary gear 3 with respect to the internal gear 2. FIG. 11 is a schematic cross-sectional view of the robot joint device 200. FIG. 11 also schematically shows the first member 201, the second member 202, and the driving source 101.

[0100] The robot joint device 200 configured in this manner functions as a joint device by the first member 201 and the second member 202 rotating relatively around the rotation axis Ax1. Here, the input shaft 500 of the gear device 1A is driven by the driving source 101, causing the first member 201 and the second member 202 to rotate relatively. At this time, the rotation (input rotation) generated by the driving source 101 is reduced in speed at a relatively high reduction ratio in the gear device 1A, and drives the first member 201 or the second member 202 with a relatively high torque. In other words, the first member 201 and the second member 202 connected by the gear device 1A can perform bending and stretching movements around the rotation axis Ax1.

[0101] The robot joint device 200 is used in a robot such as a horizontal articulated robot (SCARA robot), for example. Furthermore, the robot joint device 200 is not limited to horizontal articulated robots, but may also be used in, for example, industrial robots other than horizontal articulated robots, or non-industrial robots. Furthermore, the gear device 1A according to this embodiment is not limited to the robot joint device 200, but may also be used in, for example, a wheel device such as an in-wheel motor in a vehicle such as an automated guided vehicle (AGV).

[0102] <Modification> Embodiment 1 is merely one of various embodiments of the present disclosure. Various modifications of Embodiment 1 are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, all drawings referred to in this disclosure are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. Modifications of Embodiment 1 are listed below. The modifications described below can be applied in appropriate combinations.

[0103] The number of crankshafts 7A, 7B, 7C is not limited to three and may be two or four or more. Furthermore, if there is only one crankshaft, an internal meshing planetary gear device of an eccentric oscillating type in which the rotation axis Ax1 and the axis center Ax2 of the crankshaft coincide with each other, rather than a distributed type, is realized. In this case, when the crankshaft is driven, the planetary gear 3 oscillates, and the pair of carriers 18, 19 can be rotated relative to the gear body 22 around the rotation axis Ax1.

[0104] Furthermore, although the first embodiment exemplifies the gear device 1A having two types of planetary gears 3, the gear device 1A may have three or more planetary gears 3. For example, if the gear device 1A has three planetary gears 3, these three planetary gears 3 are preferably arranged with a phase difference of 120 degrees around the rotation axis Ax1. The gear device 1A may also have only one planetary gear 3. Alternatively, if the gear device 1A has three planetary gears 3, two of these three planetary gears 3 may be in phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0105] Furthermore, the gear component (planetary gear 3) only needs to have a boss portion 35 protruding from at least one surface in the axial direction along the rotation axis Ax1, and it is not essential that the boss portion 35 be provided only on the inner surface in the axial direction. For example, the boss portion 35 may be provided on both surfaces in the axial direction of the gear component.

[0106] Furthermore, the bearing member 6 may be a cross roller bearing, a deep groove ball bearing, a four-point contact ball bearing, or the like.

[0107] Furthermore, the number of teeth of the input gear 501, the number of teeth of the crankshaft gears 502A, 502B, and 502C, the number of outer pins 23 (the number of teeth of the internal teeth 21), and the number of teeth of the external teeth 31 described in embodiment 1 are merely examples and can be changed as appropriate.

[0108] Furthermore, the eccentric bearing 5 is not limited to a roller bearing, but may be, for example, a deep groove ball bearing, an angular contact ball bearing, or the like.

[0109] Furthermore, the material of each component of the gear device 1A is not limited to metal, but may be, for example, a resin such as engineering plastic.

[0110] Furthermore, the gear device 1A is not limited to a configuration in which the rotational force of the inner ring 61 (input side carrier 18 and output side carrier 19) is extracted as an output, as long as it can extract the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6 as an output. For example, the rotational force of the outer ring 62 (case 10) rotating relative to the inner ring 61 may be extracted as an output.

[0111] Furthermore, the lubricant is not limited to a liquid substance such as lubricating oil (oil), but may be a gel substance such as grease.

[0112] (summary) As described above, the gear component according to the first aspect is a gear component used as each of the plurality of planetary gears (3) in the internally meshing planetary gear set (1, 1A). The internally meshing planetary gear set (1, 1A) includes an internal gear (2) and a plurality of planetary gears (3). The internal gear (2) has internal teeth (21). Each of the plurality of planetary gears (3) has external teeth (31) that partially mesh with the internal teeth (21). The internally meshing planetary gear set (1, 1A) rotates the plurality of planetary gears (3) relative to the internal gear (2) about the rotation axis (Ax1) by oscillating the plurality of planetary gears (3). The gear component has a boss portion (35) that protrudes from at least one surface in the axial direction along the rotation axis (Ax1).

[0113] According to this aspect, by fastening the plurality of gear components (planetary gears 3) using the boss portion 35, the plurality of planetary gears 3 are firmly fixed together, while problems such as deformation of the planetary gears 3 are unlikely to occur. As a result, it is possible to realize gear components (planetary gears 3) that are unlikely to deform during machining of the external teeth 31, etc.

[0114] The gear component according to the second aspect is the same as that of the first aspect, except that the boss portion (35) has a fastening hole (36).

[0115] According to this embodiment, for example, by tightening fastening members such as bolts (Y1) and nuts (Y2) through the fastening holes (36), it is possible to fasten multiple gear components (planetary gears (3)) together.

[0116] In the gear component according to the third aspect, in the first or second aspect, the tip end surface 351 of the boss portion 35 is located on the same plane as the end surface 311 of the external teeth 31.

[0117] According to this embodiment, the boss portion (35) fills the gaps between the multiple gear components, so when the multiple gear components are fastened together, the boss portion (35) functions as a spacer, making it easier to prevent the gear components from deforming (bending).

[0118] An internally meshing planetary gear device (1, 1A) according to a fourth aspect includes a plurality of planetary gears (3) made of the gear components according to any one of the first to third aspects, and an internal gear (2).

[0119] According to this embodiment, it is possible to realize an internally meshing planetary gear device (1, 1A) in which deformation is unlikely to occur during machining of the external teeth (31) and the like.

[0120] A robot joint device (200) according to the fifth aspect includes an internally meshing planetary gear device (1, 1A) according to the fourth aspect, a first member (201) fixed to the internal gear (2), and a second member (202) that rotates relative to the first member (201) in accordance with the relative rotation of the planetary gear (3) with respect to the internal gear (2).

[0121] According to this embodiment, it is possible to realize a robot joint device (200) in which deformation is unlikely to occur during machining of the external teeth (31) and the like.

[0122] The manufacturing method of the internally meshing planetary gear device (1, 1A) according to the sixth aspect is the manufacturing method of the internally meshing planetary gear device (1, 1A) according to the fourth aspect, and includes a batch processing step in which multiple planetary gears (3) are processed at the same time while the multiple planetary gears (3) are coupled in the axial direction.

[0123] According to this embodiment, it is possible to realize a method for manufacturing the internally meshing planetary gear device (1, 1A) in which deformation of the external teeth (31) and the like is less likely to occur during machining.

[0124] A seventh aspect of the manufacturing method for an internal meshing planetary gear device (1, 1A) is the same as the sixth aspect, except that in the collective machining step, the plurality of planetary gears (3) are fastened in the axial direction using the boss portions (35).

[0125] According to this embodiment, it is possible to realize a method for manufacturing the internally meshing planetary gear device (1, 1A) in which deformation of the external teeth (31) and the like is less likely to occur during machining.

[0126] The configurations according to the second and third aspects are not essential for the gear component and can be omitted as appropriate. [Explanation of symbols]

[0127] 1,1A Internally meshing planetary gear unit 2 Internal gear 3 Planetary gears 21 Inner teeth 31 Outer teeth 35 Boss section 36 Fastening hole 200 Robot joint device 201 First member 202 Second member 311 End face 351 Tip surface Ax1 Rotation axis

Claims

1. an internal gear having internal teeth; a plurality of planetary gears, each having external teeth that partially mesh with the internal teeth; a gear component used as each of a plurality of planetary gears in an internally meshing planetary gear device that rotates the plurality of planetary gears relative to the internal gear about a rotation axis by oscillating the plurality of planetary gears, a boss portion protruding from at least one surface in the axial direction along the rotation shaft; Gear parts.

2. The boss portion has a fastening hole. The gear component according to claim 1 .

3. a tip end surface of the boss portion is located on the same plane as an end surface of the external teeth; The gear component according to claim 1 or 2.

4. The planetary gears are made of the gear component according to claim 1 or 2; The internal gear, Internally meshing planetary gear set.

5. The internal meshing planetary gear device according to claim 4; a first member fixed to the internal gear; a second member that rotates relative to the first member in accordance with the relative rotation of the planetary gear with respect to the internal gear, Robotic joint device.

6. A method for manufacturing the internal meshing planetary gear device according to claim 4, comprising the steps of: a batch machining step of machining the plurality of planetary gears collectively in a state in which the plurality of planetary gears are coupled in the axial direction, A method for manufacturing an internally meshing planetary gear device.

7. In the collective machining step, the plurality of planetary gears are fastened in the axial direction using the boss portions. A method for manufacturing the internal meshing planetary gear device according to claim 6.

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