Internally meshing planetary gear system and robotic joint system

Abstract

To provide an internally joined planetary gear system and a robotic joint system that easily achieve sufficient lubrication characteristics. [Solution] The crankshaft 7A oscillates the planetary gear 3 by rotating around the axis Ax2. The carrier 19 has a recess 81, which rotatably supports the crankshaft 7A within the recess 81. The regulating member 82 is positioned within the recess 81 of the carrier 19 so as to face one end face of the crankshaft 7A in the axial direction. By bringing the crankshaft 7A into contact with the regulating member 82, the movement of the crankshaft 7A toward the bottom surface 811 of the recess 81 is restricted. The regulating member 82 has a communication passage 87 that connects the spaces separated by the regulating member 82.

Description

Technical Field

[0001] The present disclosure generally relates to an internal meshing planetary gear device and a joint device for a robot, and more particularly to an internal meshing planetary gear device in which a planetary gear having external teeth is disposed inside an internal gear having internal teeth, and a joint device for a robot.

Background Art

[0002] As a related art, an eccentric swing type internal meshing planetary gear device which is a type of speed reducer is known (see, for example, Patent Document 1). The internal meshing planetary gear device according to the related art includes a crankshaft, a planetary gear (external gear) attached to the crankshaft, an internal gear (case) having internal teeth that mesh with the planetary gear, and a carrier provided so as to be rotatable relative to the internal gear.

[0003] When the crankshaft rotates by a drive source in such an internal meshing planetary gear device, the planetary gear is pushed by an eccentric body provided on the crankshaft and swings (rotates), and the carrier rotates relative to the internal gear in accordance with the swing of the planetary gear. As a result, the reduced rotation is output from the carrier or the internal gear to the mating device.

[0004] In the above related art, the carrier has a recess into which one end portion of the crankshaft is inserted. A restricting member is disposed on the bottom surface of the recess, and the restricting member restricts the movement of the crankshaft in a direction toward the bottom surface of the recess along the rotation axis of the crankshaft. A crankshaft bearing for supporting the crankshaft is provided on the inner peripheral surface of the recess, and the restricting member restricts the movement of the crankshaft bearing toward the bottom surface side in the rotation axis direction of the crankshaft bearing. Here, the inner peripheral surface of the recess has a support surface for supporting the crankshaft bearing, and a relief portion provided between the support surface and the bottom surface in the rotation axis direction and having a larger diameter than the support surface.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the configuration of the related technology described above, the movement of the crankshaft toward the bottom of the recess is restricted by bringing one end face of the crankshaft into contact with a restricting member located on the bottom of the recess. As a result, the space on the crankshaft side and the space on the bottom of the recess side are separated by the restricting member. Consequently, the circulation of the lubricant may be hindered by the restricting member, and sufficient lubrication characteristics may not be obtained.

[0007] The purpose of this disclosure is to provide an internally joined planetary gear system and a robotic joint system that can easily obtain sufficient lubrication characteristics. [Means for solving the problem]

[0008] An internally meshing planetary gear device according to one aspect of the present disclosure comprises an internal gear, planetary gears, a crankshaft, a carrier, and a regulating member, wherein the planetary gear is rotated relative to the internal gear by oscillating the planetary gear. The internal gear has an annular gear body and a plurality of external pins that constitute internal teeth and are held in a rotatable state in a plurality of internal grooves formed on the inner surface of the gear body. The planetary gear has external teeth that partially mesh with the internal teeth. The crankshaft oscillates the planetary gear by rotating about its axis. The carrier has a recess and rotatably supports the crankshaft within the recess. The regulating member is positioned within the recess of the carrier so as to face one end face of the crankshaft in the axial direction. By bringing the crankshaft into contact with the regulating member, the movement of the crankshaft toward the bottom surface of the recess is restricted. The regulating member has a communication passage that connects the spaces separated by the regulating member.

[0009] A robotic joint device according to one aspect of the present disclosure comprises: an internal meshing planetary gear device; a first member fixed to the gear body; 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. [Effects of the Invention]

[0010] According to this disclosure, there is an advantage in that it is possible to provide internally joined planetary gear systems and robotic joint systems that can easily obtain sufficient lubrication characteristics. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a perspective view showing the schematic configuration of an actuator, including an internally meshing planetary gear system, which is part of the basic configuration. [Figure 2] Figure 2 is a schematic exploded perspective view of the same internally meshed planetary gear system as seen from the input side of the rotating shaft. [Figure 3] Figure 3 is a schematic exploded perspective view of the same internally meshing planetary gear system, viewed from the output side of the rotating shaft. [Figure 4] Figure 4 is a schematic cross-sectional view of the internally meshing planetary gear set shown above. [Figure 5] Figure 5 is a cross-sectional view taken along line A1-A1 in Figure 4, showing the same internally meshed planetary gear mechanism. [Figure 6] Figure 6 is a cross-sectional view taken along line B1-B1 in Figure 4, showing the same internally meshing planetary gear system. [Figure 7] Figure 7 is a schematic diagram showing a robot joint device using the internally meshing planetary gear system described above. [Figure 8] Figure 8 is a schematic cross-sectional view showing the main parts of the internally meshing planetary gear system described above. [Figure 9] Figure 9 is a schematic cross-sectional view showing the main parts of an internally meshing planetary gear system according to Embodiment 1. [Figure 10] Figure 10 is a schematic cross-sectional view showing a modified example of a restricting member of an internally meshing planetary gear system according to Embodiment 1. [Figure 11]FIG. 11 is a schematic cross-sectional view and a schematic plan view showing another modification of the regulating member of the internal meshing planetary gear device according to Embodiment 1. [Figure 12] FIG. 12 is a schematic cross-sectional view showing a main part of the internal meshing planetary gear device according to Embodiment 2. [Figure 13] FIG. 13 is a schematic cross-sectional view showing a main part of the internal meshing planetary gear device according to Embodiment 3. [Figure 14] FIG. 14 is a schematic cross-sectional view showing a main part of the internal meshing planetary gear device according to Embodiment 4.

MODE FOR CARRYING OUT THE INVENTION

[0012] (Basic Configuration) (1) Overview Hereinafter, the overview of the internal meshing planetary gear device 1 according to this basic configuration will be described with reference to FIGS. 1 to 4. The drawings referred to in the present disclosure are all schematic drawings, and the ratios of the sizes and thicknesses of each component in the drawings do not necessarily reflect the actual dimensional ratios. For example, in FIGS. 1 to 4, the tooth profiles, dimensions, number of teeth, etc. of the internal teeth 21 and the external teeth 31 are merely schematically shown for the purpose of explanation, and are not intended to be limited to the illustrated shapes.

[0013] The internal meshing planetary gear device 1 according to this basic configuration (hereinafter, also simply referred to as "gear device 1") is a gear device including an internal gear 2 and a planetary gear 3. In this gear device 1, the planetary gear 3 is arranged inside the annular internal gear 2, and by swinging the planetary gear 3, the planetary gear 3 is rotated relative to the internal gear 2. Further, the internal meshing planetary gear device 1 further includes a bearing device 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 swing type internal meshing planetary gear device called a distribution type.

[0014] As shown in FIGS. 1 to 4, the gear device 1 according to this basic configuration includes a plurality (three in the basic configuration) of crankshafts (eccentric shafts) 7A, 7B, 7C arranged at positions offset from the axis (rotation axis Ax1) of the internal gear 2. Further, the gear device 1 includes an input shaft 500 centered on the rotation axis Ax1, which is arranged on the axis (rotation axis Ax1) of the internal gear 2, and an input gear 501 integrally formed with the input shaft 500. Crankshaft gears 502A, 502B, 502C are spline-connected to the plurality of crankshafts 7A, 7B, 7C respectively. These plurality (three in the basic configuration) of crankshaft gears 502A, 502B, 502C are arranged to mesh with the input gear 501. Therefore, when the input shaft 500 is driven, the gear device 1 drives the crankshafts 7A, 7B, 7C synchronously by the input gear 501, thereby swinging the planetary gear 3.

[0015] 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 a plurality of outer pins 23. The plurality of outer pins 23 are held on the inner peripheral surface 221 of the gear body 22 in a rotatable state and constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and a part of the external teeth 31 meshes with a part of the internal teeth 21. In this state, when the plurality of crankshafts 7A, 7B, 7C are driven, the planetary gear 3 swings, 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 tooth number difference between the planetary gear 3 and the internal gear 2 occurs between the two gears (the internal gear 2 and the planetary gear 3). Here, if the internal gear 2 is fixed, the planetary gear 3 rotates (self-rotates) with the relative rotation of the two gears. As a result, a rotational output decelerated at a relatively high reduction ratio can be obtained from the planetary gear 3 according to the tooth number difference between the two gears.

[0016] This type of gear device 1 is used to extract the rotational component of the planetary gear 3 as the rotation of a pair of carriers 18 and 19, which are relatively fixed by means such as the inner ring 61 of the bearing device 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 and 19 as the output side. In this basic configuration of the gear device 1, the pair of carriers 18 and 19 support multiple crankshafts 7A, 7B, and 7C in order to transmit the rotational component of the planetary gear 3 to the pair of carriers 18 and 19. The pair of carriers 18 and 19 are arranged on both sides in the axial direction of the planetary gear 3 (along the rotation axis Ax1) and rotatably support each crankshaft 7A, 7B, and 7C.

[0017] Here, the multiple crankshafts 7A, 7B, and 7C are inserted into multiple openings 33 formed in the planetary gear 3, and rotate relative to the internal gear 2 as the planetary gear 3 rotates. Each crankshaft 7A, 7B, and 7C has an axial portion 71 and an eccentric portion 72 that is eccentric to the axial portion 71. A pair of carriers 18 and 19 rotatably support the axial portion 71 of each crankshaft 7A, 7B, and 7C, and the eccentric portions 72 of each crankshaft 7A, 7B, and 7C are inserted into the openings 33 of the planetary gear 3. As each crankshaft 7A, 7B, and 7C rotates around its respective axial portion 71, each eccentric portion 72 rotates eccentrically (eccentric motion) relative to its respective axial portion 71. Consequently, the planetary gear 3 oscillates. As the planetary gear 3 oscillates, it partially meshes with the internal gear 2 and rotates relative to the internal gear 2. As a result, the planetary gear 3 rotates on its own central axis while revolving within the internal gear 2 around the rotation axis Ax1. As the planetary gear 3 rotates, each crankshaft 7A, 7B, and 7C revolves around the rotation axis Ax1, and the carriers 18 and 19 that support the axial center 71 of each crankshaft 7A, 7B, and 7C rotate in accordance with the revolution of each crankshaft 7A, 7B, and 7C. In this way, the rotation (rotation component) of the planetary gear 3, excluding the oscillating component (revolution component), is transmitted to the pair of carriers 18 and 19 by multiple crankshafts 7A, 7B, and 7C.

[0018] Furthermore, the gear device 1 in this basic configuration, together with the drive source 101, constitutes an actuator 100, as shown in Figure 1. In other words, the actuator 100 in this basic configuration comprises the gear device 1 and the drive source 101. The drive source 101 generates a driving force to oscillate the planetary gear 3. Specifically, the drive source 101 oscillates the planetary gear 3 by rotating the input shaft 500 around the rotation axis Ax1.

[0019] (2) Definition As used in this disclosure, "ring-shaped" means a ring-like shape that forms an enclosed space (region) at least in a plan view, and is not limited to a circular shape (ring-shaped) that is a perfect circle in a plan view, but may also be an elliptical shape, a polygonal shape, etc. Furthermore, even a shape with a bottom, such as a cup shape, is included in "ring-shaped" if its peripheral wall is ring-shaped.

[0020] In this disclosure, "revolution" means that an object revolves around an axis of rotation other than the central axis passing through the object's center (center of gravity). When an object revolves, its center moves along the orbital path centered on the axis of rotation. Therefore, for example, if an object rotates around an eccentric axis parallel to the central axis passing through its center (center of gravity), the object is revolving around the eccentric axis as its axis of rotation. As an example, the planetary gear 3 revolves inside the internal gear 2 by oscillating, so as to revolve around the axis of rotation Ax1.

[0021] Furthermore, in this disclosure, one side of the rotating shaft Ax1 (the left side in Figure 4) may be referred to as the "output side," and the other side of the rotating shaft Ax1 (the right side in Figure 4) may be referred to as the "input side." In the example in Figure 4, rotation is applied to the input shaft 500 from the "input side" of the rotating shaft Ax1, and the rotation of the pair of carriers 18 and 19 is extracted from the "output side" of the rotating shaft Ax1. However, "input side" and "output side" are merely labels used for explanatory purposes and are not intended to limit the positional relationship between the input and output as seen from the gear device 1.

[0022] In this disclosure, "axis of rotation" refers to a virtual axis (straight line) that is the center of the rotational motion of the rotating body. In other words, the axis of rotation Ax1 is a virtual axis that does not have a physical form. The input shaft 500 performs rotational motion around the axis of rotation Ax1.

[0023] In this disclosure, "internal teeth" and "external teeth" refer not to individual "teeth," but to a collection (group) of multiple "teeth." In other words, the internal teeth 21 of the internal gear 2 consist of a collection 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 consist of a collection of multiple teeth arranged on the outer circumferential surface of the planetary gear 3.

[0024] (3) Detailed configuration of the gear system The detailed configuration of the gear unit 1 related to this basic configuration will be explained below with reference to Figures 1 to 7.

[0025] Figure 1 is a perspective view showing the schematic configuration of the actuator 100 including the gear unit 1. In Figure 1, the drive source 101 is schematically shown. Figure 2 is a schematic exploded perspective view of the gear unit 1 as seen from the input side of the rotating shaft Ax1. Figure 3 is a schematic exploded perspective view of the gear unit 1 as seen from the output side of the rotating shaft Ax1. Figure 4 is a schematic cross-sectional view of the gear unit 1. Figure 5 is a cross-sectional view taken along line A1-A1 in Figure 4. Figure 6 is a cross-sectional view taken along line B1-B1 in Figure 4. However, in Figures 5 and 6, hatching is omitted for parts other than the crankshafts 7A, 7B, and 7C, even in cross-sections.

[0026] (3.1) Overall structure As shown in Figures 1 to 4, the gear unit 1 in this basic configuration comprises an internal gear 2, a planetary gear 3, a bearing device 6, a plurality of crankshafts 7A, 7B, 7C, a pair of carriers 18, 19, and an input shaft 500. Furthermore, in this basic configuration, the gear unit 1 further comprises an input gear 501, a plurality of crankshaft gears 502A, 502B, 502C, a pair of crank bearings 41, 42, an eccentric bearing 5, and a case 10. In this basic configuration, the materials of the components of the gear unit 1, such as the internal gear 2, planetary gear 3, the plurality of crankshafts 7A, 7B, 7C, and the pair of carriers 18, 19, are 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. The term "metal" (including light metals) here includes metals that have undergone surface treatment such as nitriding.

[0027] Furthermore, in this basic configuration, an internal planetary gear system using a trochoidal tooth profile is given as an example of the gear system 1. In other words, the gear system 1 in this basic configuration is equipped with an internal planetary gear 3 having a trochoidal curved tooth profile.

[0028] Furthermore, in this basic configuration, as an example, the gear unit 1 is used with the gear body 22 of the internal gear 2 fixed to a fixed member such as the case 10, together with the outer ring 62 of the bearing unit 6. As a result, the planetary gear 3 rotates relative to the fixed member (case 10, etc.) as the internal gear 2 and the planetary gear 3 rotate relative to each other.

[0029] Furthermore, in this basic configuration, when the gear unit 1 is used as the actuator 100, when a rotational force is applied to the input shaft 500 as input, a rotational force is extracted as output from the pair of carriers 18 and 19 to which the inner ring 61 of the bearing unit 6 is fixed. In other words, the gear unit 1 operates with the rotation of the input shaft 500 as the input rotation and the rotation of the pair of carriers 18 and 19 to which the inner ring 61 is fixed as the output rotation. As a result, the gear unit 1 obtains an output rotation that is reduced at a relatively high reduction ratio relative to the input rotation.

[0030] The drive source 101 is a power source such as a motor. The power generated by the drive source 101 is transmitted to the input shaft 500 in the gear unit 1. Specifically, the drive source 101 is connected to the input shaft 500, and the power generated by the drive source 101 is transmitted to the input shaft 500. This allows the drive source 101 to rotate the input shaft 500.

[0031] Furthermore, in the gear device 1 relating to this basic configuration, as shown in Figure 4, the input rotation axis Ax1 and the output rotation axis Ax1 are on the same straight line. In other words, the input rotation axis Ax1 and the output rotation axis Ax1 are coaxial. Here, the input rotation axis Ax1 is the rotation center of the input shaft 500 to which the input rotation is applied, and the output rotation axis Ax1 is the rotation center of the inner ring 61 (and a pair of carriers 18, 19) that generates the output rotation. In other words, in the gear device 1, an output rotation reduced at a relatively high reduction ratio relative to the input rotation is obtained on the same axis.

[0032] 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 its inner circumferential surface being a perfect circle in 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. All of the teeth constituting the internal teeth 21 are of the same shape and are provided at equal pitches across 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 plan view. The center of the pitch circle of the internal teeth 21 lies on the rotation axis Ax1. The internal gear 2 also 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 direction of the tooth traces is slightly smaller than the thickness direction of the internal gear 2.

[0033] Here, the internal gear 2, as described above, has an annular (circular) gear body 22 and a plurality of external pins 23. The plurality of external pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a state in which they can rotate, and constitute the internal teeth 21. In other words, the plurality of external pins 23 each function as a plurality of teeth that constitute the internal teeth 21. Specifically, as shown in Figure 2, a plurality of internal grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over the entire circumference. The plurality of internal grooves 223 are all the same shape and are provided at equal pitches. The plurality of internal grooves 223 are all 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 external pins 23 are assembled to the gear body 22 so as to fit into the plurality of internal grooves 223. Each of the plurality of external pins 23 is held in a state in which it can rotate within the internal groove 223. Furthermore, the gear body 22 is fixed to the case 10 (together with the outer ring 62). In addition, the gear body 22 has multiple fixing holes 222 (see Figure 5) for fixing.

[0034] As shown in Figures 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 its outer circumferential surface being a perfect circle in plan view. The external teeth 31 are formed on the outer circumferential surface of the annular planetary gear 3, along the circumferential direction of the planetary gear 3. All of the teeth constituting the external teeth 31 are 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 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 along the entire length in the thickness direction of the planetary gear 3. The tooth traces of the external teeth 31 are all parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 are integrally formed with the body of the planetary gear 3 from a single metal component.

[0035] Furthermore, the gear unit 1 in this basic configuration includes multiple planetary gears 3. Specifically, the gear unit 1 includes two planetary gears 3: a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged opposite each other in a direction parallel to the rotation axis Ax1. In other words, the planetary gear 3 includes a first planetary gear 301 and a second planetary gear 302 that are aligned in a direction parallel to the rotation axis Ax1 (axial direction). The shapes of the first planetary gear 301 and the second planetary gear 302 are the same.

[0036] These two planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) are positioned with a 180-degree phase difference around the rotation axis Ax1. In the example in Figure 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, which is located on the input side of the rotation axis Ax1 (right side in Figure 4), is shifted (biased) downward 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, which is located on the output side of the rotation axis Ax1 (left side in Figure 4), is shifted (biased) upward with respect to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the eccentricity of the first planetary gear 301 with respect to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 is the eccentricity of the second planetary gear 302 with respect 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.

[0037] The first planetary gear 301 and the second planetary gear 302 have centers C1 and C2 positioned 180 degrees rotationally symmetric with respect to the axis of rotation Ax1. In this basic configuration, the eccentricity ΔL1 and eccentricity ΔL2 are in opposite directions when viewed from the axis of rotation Ax1, but their absolute values ​​are the same.

[0038] More specifically, each crankshaft 7A, 7B, and 7C has two eccentric portions 72 with respect to one central axis 71. The eccentricity ΔL0 (see Figures 5 and 6) of the centers C0 of these two eccentric portions 72 from the center of the central axis 71 (axis Ax2) 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 shapes of the multiple crankshafts 7A, 7B, and 7C are common. Similarly, the shapes of the multiple crankshaft gears 502A, 502B, and 502C are also common.

[0039] Furthermore, a pair of carriers 18 and 19 are positioned 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). To distinguish between the pair of carriers 18 and 19, the carrier 18 located on the input side of the rotation axis Ax1 (right side in Figure 4) is called the "input side carrier 18," and the carrier 19 located on the output side of the rotation axis Ax1 (left side in Figure 4) is called the "output side carrier 19." Each crankshaft 7A, 7B, and 7C is held at both ends by the pair of carriers 18 and 19 via crank bearings 41 and 42. In other words, each crankshaft 7A, 7B, and 7C is held by the input side carrier 18 and the output side carrier 19 in a state that allows it to rotate on both sides of the planetary gear 3 in the direction parallel to the rotation axis Ax1 (axial direction).

[0040] Eccentric bearings 5 ​​are mounted on the eccentric portions 72 of each crankshaft 7A, 7B, and 7C. Each of the first planetary gear 301 and the second planetary gear 302 has three openings 33 corresponding to the three crankshafts 7A, 7B, and 7C. Eccentric bearings 5 ​​are housed in each of the openings 33. In other words, eccentric bearings 5 ​​are attached to the first planetary gear 301 and the second planetary gear 302, and each crankshaft 7A, 7B, and 7C is inserted into the eccentric bearings 5, thereby assembling the eccentric bearings 5 ​​and each crankshaft 7A, 7B, and 7C into the planetary gear 3. When each crankshaft 7A, 7B, and 7C rotates in the state as the eccentric bearings 5 ​​and crankshafts 7A, 7B, and 7C are assembled into the planetary gear 3, the planetary gear 3 oscillates around the rotation axis Ax1.

[0041] According to the configuration described above, when a rotational force is applied as input to the input shaft 500, the input shaft 500 rotates around the rotation axis Ax1, and this 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 mesh with the input gear 501 simultaneously rotate in the same direction at the same rotational speed. Since the crankshafts 7A, 7B, and 7C are spline-connected to each of the crankshaft gears 502A, 502B, and 502C, the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same rotational speed while being reduced by the tooth 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.

[0042] Figures 5 and 6 show the state of the first planetary gear 301 and the second planetary gear 302 at a certain point in time. Figure 5 is a cross-sectional view taken along line A1-A1 in Figure 4, showing the first planetary gear 301. Figure 6 is a cross-sectional view taken along line B1-B1 in Figure 4, showing the second planetary gear 302. As shown in Figures 5 and 6, the centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are positioned approximately 180 degrees rotationally symmetric with respect to the rotation axis Ax1. In this basic configuration, the eccentricity ΔL1 and eccentricity ΔL2 are in opposite directions when viewed from the rotation axis Ax1, but their absolute values ​​are approximately the same (both are eccentricity ΔL0). According to the above configuration, as the axial core 71 rotates (rotates) around the axis Ax2, the first planetary gear 301 and the second planetary gear 302 rotate (eccentrically) 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 almost 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.

[0043] The planetary gear 3 (first planetary gear 301 and second planetary gear 302) configured in this way is positioned inside the internal gear 2. In plan view, the planetary gear 3 is formed to be slightly smaller than the internal gear 2, and when combined with the internal gear 2, the planetary gear 3 is able to oscillate inside the internal gear 2. Here, external teeth 31 are formed on the outer circumferential surface of the planetary gear 3, and internal teeth 21 are formed on the inner circumferential surface of the internal gear 2. Therefore, when the planetary gear 3 is positioned inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

[0044] 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 in the first planetary gear 301 is located at a distance ΔL1 from the center of the pitch circle of the internal teeth 21 (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 in the second planetary gear 302 is located at a distance ΔL2 from the center of the pitch circle of the internal teeth 21 (rotation axis Ax1).

[0045] Therefore, in both the first planetary gear 301 and the second planetary gear 302, at least a portion of the external teeth 31 and internal teeth 21 will face each other with a gap in between, and if the difference in the number of teeth between the external teeth 31 and internal teeth 21 is "2" or more, the entire circumferential direction will not mesh with each other. However, since the planetary gear 3 oscillates (revolves) around the rotation axis Ax1 inside the internal gear 2, the external teeth 31 and internal teeth 21 will partially mesh. In other words, as the planetary gear 3 (first planetary gear 301 and second planetary gear 302) oscillates around the rotation axis Ax1, as shown in Figures 5 and 6, some of the teeth of the multiple teeth constituting the external teeth 31 will mesh with some of the teeth of the multiple teeth constituting the internal teeth 21. As a result, in the gear device 1, it is possible to mesh a portion of the external teeth 31 with a portion of the internal teeth 21.

[0046] Here, the number of teeth on the internal gear 21 is N (where N is a positive integer) greater than the number of teeth on the external gear 31 of the planetary gear 3. In this basic configuration, as an example, N is "2", and the number of teeth on the planetary gear 3 (external gear 31) is "2" less than the number of teeth on the internal gear 2 (internal gear 21). This difference in the number of teeth between the planetary gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear device 1.

[0047] Furthermore, 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 in the internal gear 2. Moreover, the dimension of the external teeth 31 of the combined first planetary gear 301 and the second planetary gear 302 in the tooth trace direction (direction parallel to the rotation axis Ax1) is smaller than the dimension of the internal teeth 21 in the tooth trace direction (direction parallel to the rotation axis Ax1). 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.

[0048] Here, the first planetary gear 301 and the second planetary gear 302 are internally meshed with the internal gear 2. Therefore, with each oscillation of the first planetary gear 301 and the second planetary gear 302, a circumferential phase shift occurs between them and the internal gear 2 (between the internal teeth 21 and the external teeth 31) equal to the difference in the number of teeth, causing them 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 body (and the integrated case 10) around the rotation axis Ax1.

[0049] In short, the gear device 1 in this basic configuration uses multiple crankshafts 7A, 7B, and 7C, positioned offset from the rotation axis Ax1, to oscillate a planetary gear 3, and obtains rotational output by utilizing the oscillation of the planetary gear 3. That is, in the gear device 1, as 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, relative rotation occurs between the two gears (internal gear 2 and planetary gear 3) according to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. If the internal gear 2 is fixed, the planetary gear 3 will rotate (rotate on its own axis) in conjunction with the relative rotation of the two gears. As a result, rotational output reduced at a relatively high reduction ratio according to the difference in the number of teeth between the two gears can be obtained from the planetary gear 3.

[0050] The bearing device 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 the rotation of the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and inner ring 61, the bearing device 6 has a plurality of rolling elements 63 (see Figure 4). Both the outer ring 62 and the inner ring 61 are annular components. Both the outer ring 62 and the inner ring 61 have annular shapes that are perfect circles in plan view. The inner ring 61 is slightly smaller than the outer ring 62 and is positioned inside the outer ring 62. Here, since the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is created between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61.

[0051] Multiple rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61. Multiple rolling elements 63 are arranged in a line along the circumference of the outer ring 62. All of the multiple rolling elements 63 are metal parts of the same shape and are provided at equal pitches over the entire circumference of the outer ring 62.

[0052] More specifically, the gear unit 1 in this basic configuration includes a first main bearing 601 and a second main bearing 602, which are bearing units 6, respectively. In other words, the gear unit 1 includes a pair of bearing units 6 consisting of a first main bearing 601 and a second main bearing 602. Specifically, as shown in Figure 4, the first main bearing 601 is located on the input side of the rotation axis Ax1 as viewed from the planetary gear 3 (right side in Figure 4), and the second main bearing 602 is located on the output side of the rotation axis Ax1 as viewed from the planetary gear 3 (left side in Figure 4). The pair of bearing units 6 are configured such that the first main bearing 601 and the second main bearing 602 can withstand radial loads, thrust loads (in the direction along the rotation axis Ax1), and bending forces (bending moment loads) on the rotation axis Ax1.

[0053] Here, the first main bearing 601 and the second main bearing 602 are positioned on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1 (axial direction), and are facing opposite directions in a direction parallel to the rotation axis Ax1. As an example, the pair of bearing devices 6 are of a "back-to-back combination type" in which the inner rings 61 of the first main bearing 601 and the second main bearing 602 are subjected to outward thrust loads (directions along the rotation axis Ax1). Furthermore, in the gear device 1, the first main bearing 601 and the second main bearing 602 are assembled in a state in which appropriate preload is applied to the inner rings 61 by tightening them in a direction that brings their respective inner rings 61 closer together.

[0054] Furthermore, in the gear device 1 according to this basic configuration, the input carrier 18 and the output carrier 19 are arranged on both sides 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 (see Figure 4) of the planetary gear 3. Specifically, as shown in Figure 4, the input carrier 18 is positioned on the input side of the rotation axis Ax1 (right side in Figure 4) as viewed from the planetary gear 3, and the output carrier 19 is positioned on the output side of the rotation axis Ax1 (left side in Figure 4) as viewed from the planetary gear 3. The inner rings 61 of the pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed to the input carrier 18 and the output carrier 19, respectively. In this basic configuration, as an example, the inner ring 61 of the first main bearing 601 is fixed to the input carrier 18. Similarly, the inner ring 61 of the second main bearing 602 is fixed to the output carrier 19.

[0055] The output carrier 19 has multiple (for example, three) carrier pins 191 (see Figure 2) that protrude from one surface of the output carrier 19 toward the input side of the rotation axis Ax1. These multiple carrier pins 191 each pass through multiple (for example, three) carrier holes 34 formed in the planetary gear 3, and their tips are fixed to the input carrier 18 by carrier bolts. Here, a gap is ensured between the carrier pins 191 and the inner circumferential surface of the carrier holes 34, and the carrier pins 191 are movable within the carrier holes 34, that is, they are movable relative to the center of the carrier holes 34. As a result, the carrier pins 191 do not come into contact with the inner circumferential surface of the carrier holes 34 when the planetary gear 3 oscillates.

[0056] With the above configuration, the gear unit 1 is used to extract the rotation equivalent to the rotation component of the planetary gear 3 as the rotation of the input carrier 18 and output carrier 19 to which the inner rings 61 of the pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed. In other words, in this basic configuration, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the input carrier 18 and output carrier 19. In this basic configuration, as an example, the gear unit 1 is used with the outer rings 62 (see Figure 4) of the pair of bearing devices 6 (first main bearing 601 and second main bearing 602) fixed to the case 10, which is a fixed member. In other words, the planetary gear 3 is connected to the input carrier 18 and output carrier 19, which are rotating members, by multiple crankshafts 7A, 7B, and 7C, and the gear body 22 is fixed to a stationary member. Therefore, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the rotating members (input carrier 18 and output carrier 19). In other words, in this basic configuration, when the planetary gear 3 rotates relative to the gear body 22, the rotational force of the input carrier 18 and output carrier 19 is extracted as an output.

[0057] Furthermore, in this basic configuration, the case 10 is seamlessly integrated with the gear body 22 of the internal gear 2. In other words, in a direction parallel to the rotation axis Ax1, the fixed member, the gear body 22, and the case 10 are provided seamlessly and continuously.

[0058] More specifically, the case 10 is cylindrical and constitutes the outer casing of the gear unit 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 surface of the case 10 is a perfect circle centered on the rotation axis Ax1 when viewed from a plan view (viewed from one side in the axial direction). The case 10 is formed in a cylindrical shape with both axial end faces open. Here, the gear body 22 of the internal gear 2 is seamlessly integrated into the case 10, and the case 10 and the gear body 22 are treated as a single part. Therefore, the inner surface of the case 10 includes the inner surface 221 of the gear body 22. Furthermore, the outer rings 62 of a pair of bearing devices 6 (first main bearing 601 and second main bearing 602) are fixed to the case 10. In other words, the outer ring 62 of the first main bearing 601 is fitted and fixed to the input side of the rotation axis Ax1 (right side in Figure 4) as viewed from the gear body 22 on the inner circumferential surface of the case 10. On the other hand, the outer ring 62 of the second main bearing 602 is fitted and fixed to the output side of the rotation axis Ax1 (left side in Figure 4) as viewed from the gear body 22 on the inner circumferential surface of the case 10.

[0059] Furthermore, the input side (right side in Figure 4) end face of the rotating shaft Ax1 in case 10 is closed by the input side carrier 18, and the output side (left side in Figure 4) end face of the rotating shaft Ax1 in case 10 is closed by the output side carrier 19. As a result, as shown in Figure 4, components such as the planetary gear 3 (first planetary gear 301 and second planetary gear 302), multiple external pins 23, and eccentric bearing 5 are housed in the space enclosed by case 10, the input side carrier 18, and the output side carrier 19.

[0060] Each of the multiple (three in the basic configuration) crankshafts 7A, 7B, and 7C has an axial core 71 and two eccentric parts 72. The axial core 71 has a cylindrical shape, with at least its outer surface being a perfect circle in plan view. The axis Ax2, which is the center of the axial core 71, is parallel to the rotation axis Ax1. The axis 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 rotation axis Ax1. Each eccentric part 72 has a disc shape, with at least its outer surface being a perfect circle in plan view. The center (central axis) C0 of each eccentric part 72 is parallel to the rotation axis Ax1 and is positioned radially offset from the rotation axis Ax1. Here, the distance ΔL0 between the axis Ax2 and the center C0 (see Figures 5 and 6) is the amount of eccentricity of the eccentric part 72 relative to the axial core 71. The eccentric portion 72 has a flange shape that protrudes from the outer circumferential surface of the shaft portion 71 around its entire circumference at the center of the shaft portion 71 in the longitudinal direction (axial direction). With the above configuration, each crankshaft 7A, 7B, and 7C will undergo eccentric motion as the shaft portion 71 rotates around the shaft Ax2.

[0061] In this basic configuration, the central shaft 71 and the two eccentric shafts 72 are integrally formed from a single metal component, thereby realizing seamless crankshafts 7A, 7B, and 7C. These crankshafts 7A, 7B, and 7C are combined with the planetary gear 3 along with the eccentric bearing 5. Therefore, when the crankshafts 7A, 7B, and 7C rotate with the planetary gear 3 assembled to the eccentric bearing 5, the planetary gear 3 oscillates around the rotation axis Ax1.

[0062] The eccentric bearing 5 has multiple rolling elements 51 (see Figure 4) and is a component that absorbs the rotational component of the rotation of the crankshafts 7A, 7B, and 7C, and transmits only the rotational component (orbital component) of the crankshafts 7A, 7B, and 7C to the planetary gear 3. The multiple rolling elements 51 are arranged between the outer circumferential surface of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C and the inner circumferential surface of each opening 33 of the planetary gear 3. In other words, the eccentric portion 72 of each crankshaft 7A, 7B, and 7C functions as the inner ring of the eccentric bearing 5, and the inner circumferential surface of each opening 33 of the planetary gear 3 functions as the outer ring of the eccentric bearing 5.

[0063] With the eccentric bearing 5 and multiple crankshafts 7A, 7B, and 7C assembled to the planetary gear 3, when each crankshaft 7A, 7B, and 7C rotates (rotates), each eccentric part 72 rotates (performs eccentric motion) around the axis Ax2. Since the planetary gear 3 is installed in a direction parallel to the rotation axis Ax1 (axial direction) corresponding to each eccentric part 72, the eccentric motion of each eccentric part 72 is transmitted to the planetary gear 3 via the eccentric bearing 5, and the planetary gear 3 oscillates around the rotation axis Ax1. In other words, the eccentric motion of the eccentric parts 72 on the crankshafts 7A, 7B, and 7C is transmitted to the planetary gear 3. The eccentric bearing 5 plays a role in mitigating friction and other issues caused by relative rotation resulting from the speed difference between the eccentric motion of the eccentric portion 72 of each crankshaft 7A, 7B, and 7C (i.e., the rotation of each crankshaft 7A, 7B, and 7C) and the revolution of the planetary gear 3, as well as in power transmission.

[0064] In the gear device 1 with the configuration described above, a rotational force is applied as input to the input shaft 500, causing the input shaft 500 to rotate around the rotation axis Ax1, and the planetary gear 3 oscillates (revolves) around the rotation axis Ax1. At this time, the planetary gear 3 oscillates inside the internal gear 2, with a portion of the external teeth 31 meshing with a portion of the internal teeth 21. As the input shaft 500 rotates, the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. This generates a relative rotation between the two gears (internal gear 2 and planetary gear 3) corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2. The rotation (rotation component) of the planetary gear 3, excluding the oscillating component (revolution component), is transmitted to the pair of carriers 18 and 19 by multiple crankshafts 7A, 7B, and 7C. As a result, the pair of carriers 18 and 19 will produce rotational output that is reduced at a relatively high reduction ratio, depending on the difference in the number of teeth of the two gears.

[0065] Incidentally, in the gear unit 1 relating 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 unit 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 equation 1.

[0066] R1 = V2 / (V1 - V2) (Equation 1) In short, the smaller the difference in the number of teeth between the internal gear 2 and the planetary gear 3 (V1-V2), the larger the reduction ratio R1. For 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", so from equation 1 above, the reduction ratio R1 is "35". In this case, when viewed from the input side of the rotation axis Ax1, each crankshaft 7A, 7B, 7C rotates clockwise one full turn (360 degrees) around the axis Ax2 of the shaft center 71 (see Figures 5 and 6), the pair of carriers 18, 19 rotate counterclockwise around the rotation axis Ax1 by the amount of the difference in the number of teeth "2" (i.e., about 10.3 degrees).

[0067] According to the gear unit 1 of this basic configuration, such a high reduction ratio R1 can be achieved with the combination of the internal gear 2 and the planetary gear 3. Furthermore, between the input gear 501 and the multiple crankshaft gears 502A, 502B, and 502C, an appropriate reduction ratio can be achieved depending on the number of teeth of the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, a high reduction ratio can be achieved for the gear unit 1 as a whole.

[0068] As shown in Figure 7, the gear device 1 according to this basic configuration, together with the first member 201 and the second member 202, constitutes a robot joint device 200. In other words, the robot joint device 200 according to this basic configuration comprises the gear device 1, the first member 201, and the second member 202. The first member 201 is fixed to the gear body 22. 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. Figure 7 is a schematic cross-sectional view of the robot joint device 200. Also, Figure 7 schematically represents the first member 201, the second member 202, and the drive source 101.

[0069] The robot joint device 200 configured in this way functions as a joint device by the relative rotation of the first member 201 and the second member 202 around the rotation axis Ax1. Here, the input shaft 500 of the gear device 1 is driven by the drive source 101, causing the first member 201 and the second member 202 to rotate relative to each other. At this time, the rotation (input rotation) generated by the drive source 101 is reduced by the gear device 1 at a relatively high reduction ratio, driving the first member 201 or the second member 202 with relatively high torque. In other words, the first member 201 and the second member 202, which are connected by the gear device 1, can perform bending and extending movements around the rotation axis Ax1.

[0070] The robot joint device 200 is used in robots such as horizontal articulated robots (SCARA type robots). Furthermore, the robot joint device 200 is not limited to horizontal articulated robots, but may also be used in industrial robots other than horizontal articulated robots, or in robots other than industrial robots. In addition, the gear device 1 relating to this basic configuration is not limited to the robot joint device 200, but may also be used as a wheel device such as an in-wheel motor in vehicles such as automated guided vehicles (AGVs).

[0071] (3.2) Crankshaft support structure Next, the support structure of the crankshafts 7A, 7B, and 7C used in the gear unit 1 relating to this basic configuration will be explained with reference to Figure 8. Since the multiple (in this case, three) crankshafts 7A, 7B, and 7C have a common configuration, including their support structure, the following explanation will use crankshaft 7A as an example. Figure 8 is a schematic cross-sectional view of the main part of the gear unit 1 (the area corresponding to region Z1 in Figure 4). In Figure 8, the illustration of the bearing device 6 (first main bearing 601 and second main bearing 602) is simplified, and the illustration of the inner ring 61, outer ring 62, and multiple rolling elements 63 is omitted.

[0072] The crankshaft 7A is supported at both ends in the axial direction (parallel to the axis Ax2) by a pair of carriers 18 and 19 via crank bearings 41 and 42. Specifically, the input side (right side in Figure 8) axis 71 of the crankshaft 7A is supported by the input side carrier 18 via crank bearing 41, and the output side (left side in Figure 8) axis 71 of the crankshaft 7A is supported by the output side carrier 19 via crank bearing 42. As a result, the crankshaft 7A is supported by the pair of carriers 18 and 19 in a state that allows it to rotate.

[0073] In this basic configuration, as an example, each crank bearing 41, 42 is a needle bearing (needle roller bearing). Each crank bearing 41, 42 has an outer ring 401, a plurality of rolling elements 402, and a cage 403. Here, the axial center 71 of the crankshaft 7A functions as the inner ring of each crank bearing 41, 42.

[0074] The outer ring 401 is formed in an annular shape that forms a perfect circle when viewed from one side in the axial direction (for example, the input side). The inner diameter of the outer ring 401 is slightly larger than the outer diameter of the shaft core 71, and it is positioned around the shaft core 71 of the crankshaft 7A. In other words, because the inner diameter of the outer ring 401 is larger than the outer diameter of the shaft core 71, a gap is created between the inner surface of the outer ring 401 and the outer surface of the shaft core 71.

[0075] Each of the multiple rolling elements 402 is formed in a cylindrical shape with length in the axial direction (parallel to the axis Ax2). The multiple rolling elements 402 are arranged between the inner circumferential surface of the outer ring 401 and the outer circumferential surface of the axis portion 71 of the crankshaft 7A. The multiple rolling elements 402 are arranged in a line along the circumference of the outer ring 401. All of the multiple rolling elements 402 are metal parts of the same shape and are provided at equal pitches over the entire circumference of the outer ring 401.

[0076] In this basic configuration, the materials of the outer ring 401 and the multiple rolling elements 402, which are components of the crank bearings 41 and 42, are metals such as stainless steel, bearing steel, carbon steel for machine structural use, chromium-molybdenum steel, phosphor bronze, or aluminum bronze, or light metals such as aluminum or titanium. The term "metal" (including light metals) here includes metals that have undergone surface treatment such as nitriding. Furthermore, the surface treatment may include blackening treatment (fermite treatment) that forms a black oxide film on the surface. Blackening treatment is effective in preventing white layer peeling due to hydrogen embrittlement, where hydrogen penetrates and is absorbed from the metal surface, and in suppressing creep of the outer ring 401.

[0077] The retainer 403 is a member that holds a plurality of rolling elements 402 between the inner circumferential surface of the outer ring 401 and the outer circumferential surface of the shaft core 71. The retainer 403 is positioned between the inner circumferential surface of the outer ring 401 and the outer circumferential surface of the shaft core 71. The retainer 403 is formed in an annular shape that forms a perfect circle when viewed from one side in the axial direction (for example, the input side). The retainer 403 has a plurality of pockets in the circumferential direction (the circumferential direction of the outer ring 401). The retainer 403 holds a plurality of rolling elements 402 by accommodating a rolling element 402 in each of these pockets. The retainer 403 holds the plurality of rolling elements 402 at equal pitches between the outer ring 401 and the inner ring (shaft core 71) by holding the plurality of rolling elements 402 in a rotatable state. The retainer 403 is a molded product of resin (synthetic resin) or the like.

[0078] Thus, the crankshaft 7A is supported at both axial ends by a pair of carriers 18 and 19 via crank bearings 41 and 42, and is supported so as to be able to rotate while passing through the planetary gear 3.

[0079] Incidentally, the gear device 1 relating to this basic configuration has a structure for restricting the axial movement of the crankshaft 7A (in the direction parallel to the axis Ax2). Roughly speaking, the axial movement of the crankshaft 7A is restricted by a structure in which the crankshaft 7A is sandwiched from both sides in the axial direction by a pair of carriers 18 and 19.

[0080] More specifically, in this basic configuration, the output carrier 19 has a recess 81 that opens toward the axial output side (right side in Figure 8). The output carrier 19 rotatably supports one end (axis center 71) of the crankshaft 7A within the recess 81 via a crank bearing 42. The gear device 1 further includes a restricting member 82 positioned within the recess 81. The restricting member 82 restricts the movement of the crankshaft 7A toward the bottom surface 811 side of the recess 81 (left side in Figure 8) by contacting the crankshaft 7A.

[0081] Here, with respect to the crank bearing 42, its relative movement relative to the crankshaft 7A toward the bottom surface 811 side of the recess 81 (left side in Figure 8) is restricted in the axial direction, while it is spaced apart from the restricting member 82. In other words, the restricting member 82 directly restricts the movement of the crankshaft 7A toward the bottom surface 811 side, thereby indirectly restricting the movement of the crank bearing 42 toward the bottom surface 811 side, which is restricted from the relative movement of the crankshaft 7A.

[0082] As described above, the gear device 1 according to this basic configuration comprises an internal gear 2, a planetary gear 3, crankshafts 7A, 7B, 7C, a carrier 19, and a regulating member 82. The internal gear 2 has an annular gear body 22 and a plurality of external pins 23 that are held in a rotatable state in a plurality of internal grooves 223 formed on the inner circumferential surface 221 of the gear body 22 and constitute the internal teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The crankshafts 7A, 7B, 7C oscillate the planetary gear 3 by rotating around the axis Ax2. The carrier 19 has a recess 81 and rotatably supports the crankshafts 7A, 7B, 7C within the recess 81 via crank bearings 42. The regulating member 82 is positioned within the recess 81 of the carrier 19 so as to face one end face (the left end face in Figure 8) of the crankshafts 7A, 7B, 7C in the axial direction. The gear unit 1 rotates the planetary gear 3 relative to the internal gear 2 by oscillating the planetary gear 3. The gear unit 1 restricts the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 of the recess 81 by bringing the crankshafts 7A, 7B, and 7C into contact with the regulating member 82. The crank bearing 42 is spaced apart from the regulating member 82 in the axial direction, and its relative movement relative to the crankshafts 7A, 7B, and 7C toward the bottom surface 811 in the axial direction is restricted.

[0083] With this configuration, the restricting member 82 positioned within the recess 81 of the carrier 19 can directly restrict the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 of the recess 81 (left side in Figure 8) in the axial direction, and the movement of the crank bearing 42 toward the bottom surface 811 (left side in Figure 8). In this case, it is not necessary to form a relief portion on the inner circumferential surface 812 of the recess 81 that is larger in diameter than the support surface (which supports the crank bearing 42), making it easier to simplify the shape of the carrier 19. Therefore, the gear device 1 according to this basic configuration has the advantage of making it easier to simplify the shape of each component.

[0084] To explain in more detail, the recess 81 is formed in a circular shape that forms a perfect circle when viewed from one side in the axial direction (for example, the input side). The inner diameter of the recess 81 is approximately the same as the outer diameter of the outer ring 401 of the crank bearing 42, and the crank bearing 42 is positioned so as to be fitted into the recess 81.

[0085] A step 811A is formed on the bottom surface 811 of the recess 81 at the boundary between the central part and the outer periphery, and the recess 81 is deeper inside the step 811A than outside the step 811A. In the carrier 19, a hole 192 is formed in the central part of the inner region of the bottom surface 811 of the recess 81 that penetrates the carrier 19 in the axial direction. In addition, a step 812A is formed on the inner circumferential surface 812 of the recess 81 at the boundary between the bottom surface 811 side and the opening side in the axial direction, and the recess 81 is smaller in diameter on the bottom surface 811 side of the step 812A than on the opening side of the step 812A.

[0086] The restricting member 82 is formed in an annular shape that forms a perfect circle when viewed from one side in the axial direction (for example, the input side). The outer diameter of the restricting member 82 is approximately the same as the inner diameter of the step 811A on the bottom surface 811 of the recess 81, and the restricting member 82 is positioned so as to fit into the space enclosed by the step 811A. The restricting member 82 is housed in the recess 81 with the side opposite to the crankshaft 7A (the output side) in contact with the bottom surface 811 of the recess 81.

[0087] Here, the restricting member 82 has a through hole 821 that penetrates the restricting member 82 in the axial direction. The through hole 821 is located in the center of the restricting member 82 when viewed from one side in the axial direction (for example, the input side). The through hole 821 communicates with a hole 192 formed in the bottom surface 811 of the recess 81 of the carrier 19. This allows lubricant (lubricating oil) to flow through the through hole 821, making it easier to ensure lubrication of, for example, the crank bearing 42.

[0088] Here, as shown in Figure 8, in this basic configuration, the gear unit 1 is equipped with a retaining ring 83, and the relative positioning of the crank bearing 42 with respect to the crankshaft 7A is achieved by the retaining ring 83. The retaining ring 83 is, for example, a C-ring or an E-ring, and is attached to the axial output end (left side in Figure 8) of the crankshaft 7A by utilizing a groove formed on the outer circumferential surface of the crankshaft 7A. In this basic configuration, an annular washer 84 is placed between the retaining ring 83 and the crankshaft bearing 42.

[0089] In short, the relative movement of the crank bearing 42 toward the bottom surface 811 side of the crankshaft 7A is restricted by a retaining ring 83 attached to the crankshaft 7A. With this configuration, the relative movement of the crank bearing 42 toward the crankshaft 7A can be restricted with a relatively simple structure.

[0090] Furthermore, in this basic configuration, the outer ring 401 of the crank bearing 42 is fitted into the recess 81 of the carrier 19 and does not move axially at all. In other words, in this basic configuration, the only parts of the crank bearing 42 that are of concern to move axially are the multiple rolling elements 402 and the cage 403. Therefore, in this basic configuration, the retaining ring 83 restricts the movement of the multiple rolling elements 402 toward the bottom surface 811, either directly or indirectly (via the cage 403).

[0091] Thus, the crank bearing 42 has a plurality of rolling elements 402, and the relative movement of at least a plurality of rolling elements 402 toward the bottom surface 811 side relative to the crankshaft 7A is restricted. This makes it possible to restrict the relative movement of the crank bearing 42 toward the crankshaft 7A with a relatively simple structure. In particular, by interposing a washer 84 between the retaining ring 83 and the crank bearing 42, the relative movement of the crank bearing 42 toward the crankshaft 7A can be restricted without hindering the movement of the crank bearing 42.

[0092] Furthermore, as described above, the gear device 1 relating to this basic configuration is a "distribution type" gear device 1 in which a rotational force is applied as input to the input shaft 500, causing the input shaft 500 to rotate around the rotation axis Ax1, and this rotational force is distributed from the input gear 501 to multiple crankshafts 7A, 7B, and 7C. In other words, the gear device 1 is equipped with a distribution unit that distributes the rotation of one input gear 501 to multiple crankshafts 7A, 7B, and 7C via multiple crankshaft gears 502A, 502B, and 502C. The planetary gear 3 oscillates due to the rotation of the multiple crankshafts 7A, 7B, and 7C.

[0093] Thus, in a gear device 1 having multiple (in this case, three) crankshafts 7A, 7B, and 7C, the support structure for crankshaft 7A described above is applied to all of the crankshafts 7A, 7B, and 7C. In other words, for each of the multiple crankshafts 7A, 7B, and 7C, the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 of the recess 81 is restricted by bringing the crankshafts 7A, 7B, and 7C into contact with the restricting member 82. Furthermore, for each of the multiple crankshafts 7A, 7B, and 7C, the crank bearing 42 is spaced apart from the restricting member 82 in the axial direction, and its relative movement toward the bottom surface 811 of the crankshafts 7A, 7B, and 7C in the axial direction is restricted. Therefore, the gear device 1 according to this basic configuration has the advantage of making it easier to simplify the shape of each component.

[0094] (4) Variations The basic configuration is merely one of many examples provided in this disclosure. The basic configuration can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. Furthermore, the drawings referenced in this disclosure are all schematic, and the ratios of the size and thickness of each component shown in the drawings do not necessarily reflect the actual dimensional ratios. The following lists some modifications of the basic configuration. These modifications can be combined and applied as appropriate.

[0095] The number of crankshafts 7A, 7B, and 7C is not limited to "3"; it may be 2 or 4 or more. Furthermore, if there is only one crankshaft, an eccentric oscillating internal meshing planetary gear system can be realized where the rotation axis Ax1 and the axis Ax2 of the crankshaft coincide, rather than a distribution type. In this case, the planetary gear 3 oscillates when the crankshaft is driven, and the pair of carriers 18 and 19 can be rotated relative to the gear body 22 around the rotation axis Ax1.

[0096] Furthermore, while the basic configuration illustrates two types of gear systems 1 with planetary gears 3, the gear system 1 may have three or more planetary gears 3. For example, if the gear system 1 has three planetary gears 3, it is preferable that these three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. Alternatively, the gear system 1 may have only one planetary gear 3. Or, if the gear system 1 has three planetary gears 3, two of these three planetary gears 3 may be in the same phase, and the remaining planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0097] Furthermore, the bearing device 6 may be an angular contact ball bearing, a cross roller bearing, a deep groove ball bearing, or a four-point contact ball bearing, etc. The rolling elements 63 are not limited to being substantially cylindrical (approximately cylindrical), but may also be, for example, frustoconical.

[0098] 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 external pins 23 (number of teeth of internal teeth 21), and the number of teeth of external teeth 31, as explained in the basic configuration, are merely examples and can be changed as appropriate.

[0099] Furthermore, the eccentric bearing 5 is not limited to a roller bearing; for example, it may be a deep groove ball bearing or an angular contact ball bearing.

[0100] Furthermore, the crank bearings 41 and 42 are not limited to needle bearings, but may also be, for example, deep groove ball bearings or angular contact ball bearings.

[0101] Furthermore, the material of each component of the gear unit 1 is not limited to metal, but may also be, for example, a resin such as engineering plastic. Conversely, the material of the retainer 403 is not limited to resin, but may also be, for example, metal.

[0102] Furthermore, the gear unit 1 only needs to be able to output the relative rotation between the inner ring 61 and the outer ring 62 of the bearing unit 6, and is not limited to a configuration in which the rotational force of the inner ring 61 (input carrier 18 and output carrier 19) is output. For example, the rotational force of the outer ring 62 (case 10) that rotates relative to the inner ring 61 may be output.

[0103] Furthermore, in the basic configuration, a relief portion with a larger diameter than the support surface (which supports the crank bearing 42) may be formed on the inner circumferential surface 812 of the recess 81. This makes it easier to remove machining chips during honing of the recess 81.

[0104] Furthermore, the lubricant is not limited to liquid substances such as lubricating oil, but may also be a gel-like substance such as grease.

[0105] (Embodiment 1) As shown in Figure 9, the internally meshing planetary gear unit 1A (hereinafter also simply referred to as "gear unit 1A") according to this embodiment differs from the gear unit 1 in the support structure of the crankshafts 7A, 7B, and 7C. Hereafter, components similar to those in the basic configuration will be denoted by common reference numerals and their descriptions will be omitted as appropriate.

[0106] In the gear apparatus 1A according to this embodiment, the multiple (in this case, three) crankshafts 7A, 7B, and 7C have a common configuration, including their support structure. Therefore, in the following description, crankshaft 7A will be used as an example among the multiple crankshafts 7A, 7B, and 7C. Figure 9 is a schematic cross-sectional view of the main part of the gear apparatus 1A (the area corresponding to region Z1 in Figure 4). In Figure 9, the illustration of the bearing device 6 (first main bearing 601 and second main bearing 602) is simplified, and the illustration of the inner ring 61, outer ring 62, and multiple rolling elements 63 is omitted.

[0107] In other words, in the gear apparatus 1A according to this embodiment, the regulating member 82 has rolling elements 822. Here, the regulating member 82 rotatably supports the crankshaft 7A relative to the carrier 19 by the rolling of the rolling elements 822. That is, the regulating member 82 is a rolling bearing having rolling elements 822, and it rotatably supports the crankshaft 7A relative to the carrier 19 by utilizing the rolling of the rolling elements 822.

[0108] Specifically, in this embodiment, the regulating member 82 includes (a plurality of) rolling elements 822, a fixed member 823, a movable member 824, and a cage 825. The movable member 824 is configured to be rotatable relative to the fixed member 823 via the (a plurality of) rolling elements 822. The regulating member 82 is a thrust bearing that supports an axial load (a load in the direction of the axis Ax2), and the fixed member 823 and the movable member 824 constitute a pair of raceway plates facing each other in the direction of the axis Ax2. In particular, in this embodiment, the regulating member 82 is a thrust ball bearing having a plurality of spherical rolling elements 822.

[0109] The fixed member 823 and the movable member 824 are both annular metal parts. Both the fixed member 823 and the movable member 824 have annular shapes that form a perfect circle centered on the axis Ax2 in a plan view. The inner diameter of the fixed member 823 is the same as the inner diameter of the movable member 824, and the outer diameter of the fixed member 823 is the same as the outer diameter of the movable member 824. The fixed member 823 and the movable member 824 are positioned opposite each other in the direction of the axis Ax2 with a predetermined gap between them. The fixed member 823 is located on the output side of the rotation axis Ax1 (left side in Figure 9), and the movable member 824 is located on the input side of the rotation axis Ax1 (right side in Figure 9).

[0110] Multiple rolling elements 822 are arranged in the gap between the fixed member 823 and the movable member 824. The multiple rolling elements 822 are arranged in a line in the circumferential direction of the fixed member 823. All of the multiple rolling elements 822 are metal parts of the same shape and are provided at equal pitches over the entire circumferential area of ​​the fixed member 823. As the multiple rolling elements 822 roll, the movable member 824 rotates relative to the fixed member 823 around the axis Ax2.

[0111] The retainer 825 is a metal component formed in an annular shape. The retainer 825 is positioned in the gap between the fixed member 823 and the movable member 824. The retainer 825 holds a plurality of rolling elements 822 at equal pitches. The rolling elements 822 roll between the opposing surfaces of the fixed member 823 and the movable member 824 while being held by the retainer 825.

[0112] The fixing member 823 is fixed to the carrier 19 by fitting into the step 811A formed on the bottom surface 811 of the recess 81. In other words, the fixing member 823 is fitted and fixed to the central part of the inner region of the step 811A on the bottom surface 811 of the recess 81 on the carrier 19.

[0113] The outer diameter of the movable member 824 is approximately the same as the outer diameter of the axial center portion 71 of the crankshaft 7A. The end face of the output side (left side in Figure 9) of the rotation axis Ax1 at the axial center portion 71 of the crankshaft 7A contacts the movable member 824. In other words, the restricting member 82 restricts the movement of the crankshaft 7A toward the bottom surface 811 side (left side in Figure 9) of the recess 81 by bringing the crankshaft 7A into contact with the movable member 824.

[0114] In other words, the gear device 1A according to this embodiment restricts the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 of the recess 81 by bringing the crankshafts 7A, 7B, and 7C into contact with the restricting member 82. The restricting member 82 has rolling elements 822, and the rolling of the rolling elements 822 rotatably supports the crankshafts 7A, 7B, and 7C relative to the carrier 19.

[0115] With this configuration, the regulating member 82 having rolling elements 822 can restrict the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 side of the recess 81 (left side in Figure 9) in the axial direction. Here, the rolling of the rolling elements 822 of the regulating member 82 allows the crankshafts 7A, 7B, and 7C to be rotatably supported relative to the carrier 19, thereby reducing frictional losses between the crankshafts 7A, 7B, and 7C and the regulating member 82. As a result, the gear device 1A according to this embodiment has the advantage of easily minimizing power losses.

[0116] Furthermore, in this embodiment, the restricting member 82 further comprises a fixed member 823 and a movable member 824 configured to be rotatable relative to each other via rolling elements 822. By fixing the fixed member 823 to the carrier 19 and bringing the crankshafts 7A, 7B, and 7C into contact with the movable member 824, the movable member 824 can restrict the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 of the recess 81. Here, the rotation of the movable member 824 together with the crankshafts 7A, 7B, and 7C reduces frictional losses between the crankshafts 7A, 7B, and 7C and the restricting member 82.

[0117] Furthermore, in this embodiment, the restricting member 82 includes a thrust bearing. As a result, the restricting member 82 can reduce frictional losses between the crankshafts 7A, 7B, 7C and the restricting member 82 through the rolling of the rolling elements 822. Moreover, by supporting the axial load (load in the direction of the axis Ax2), the restricting member 82 can restrict the movement of the crankshafts 7A, 7B, 7C toward the bottom surface 811 side of the recess 81.

[0118] Furthermore, in this embodiment, as shown in the blown-out in Figure 9, the restricting member 82 has a connecting passage 87 that connects the spaces separated by the restricting member 82. In other words, the spaces separated by the restricting member 82 are continuous through the connecting passage 87 provided in the restricting member 82. In this embodiment, the gaps between the multiple rolling elements 822 in the space between the fixed member 823 and the movable member 824 serve as the connecting passage 87, connecting the inside (through hole 821) of the restricting member 82 to the outside of the restricting member 82.

[0119] In other words, by bringing one end face of the crankshafts 7A, 7B, and 7C into contact with the restricting member 82 located on the bottom surface 811 of the recess 81, the movement of the crankshafts 7A, 7B, and 7C toward the bottom surface 811 of the recess 81 is restricted. As a result, the space on the side of the crankshafts 7A, 7B, and 7C is separated from the space on the bottom surface 811 of the recess 81 by the restricting member 82. Therefore, without the connecting passage 87, the circulation of lubricant may be hindered by the restricting member 82 between the space on the side of the crankshafts 7A, 7B, and 7C and the space on the bottom surface 811 of the recess 81, potentially preventing sufficient lubrication characteristics from being obtained.

[0120] In contrast, in the gear apparatus 1A according to this embodiment, the spaces separated by the restricting member 82 are connected by the connecting passage 87 of the restricting member 82, so that lubricant can be circulated between both sides of the restricting member 82 through the connecting passage 87. As a result, there is an advantage in that sufficient lubrication characteristics can be easily obtained.

[0121] Here, the connecting passage 87 constitutes a lubrication path for the lubricant. In other words, the lubricant can be circulated through the connecting passage 87 of the regulating member 82. This makes it possible to supply a sufficient amount of lubricant to, for example, the crankshafts 7A, 7B, 7C and the crank bearing 42, which are located inside the recess 81, and thus it is easier to obtain sufficient lubrication characteristics.

[0122] Furthermore, the regulating member 82 has multiple connecting passages 87. In other words, the regulating member 82 has multiple connecting passages 87. In this embodiment, as described above, each of the gaps between the multiple rolling elements 822 in the space between the fixed member 823 and the movable member 824 constitutes a connecting passage 87, so multiple connecting passages 87 are formed in the regulating member 82. As a result, compared to the case of a single connecting passage 87, lubricant circulation is made easier, and more sufficient lubrication characteristics are more easily obtained.

[0123] Furthermore, in this embodiment, the communication passage 87 includes a first path 87A that extends radially along the crankshafts 7A, 7B, and 7C. In this embodiment, as described above, each of the gaps between the multiple rolling elements 822 in the space between the fixed member 823 and the movable member 824 constitutes a communication passage 87, so the regulating member 82 has multiple first paths 87A that extend radially from the axis Ax2. This allows the inside of the regulating member 82 (through hole 821) and the outside of the regulating member 82 to communicate through the first paths 87A.

[0124] Furthermore, in this embodiment, the communication passage 87 includes a communication hole formed inside the restricting member 82. In other words, in this embodiment, as described above, each of the gaps between the multiple rolling elements 822 in the space between the fixed member 823 and the movable member 824 constitutes a communication passage 87, so the communication passage 87 is a communication hole formed inside the restricting member 82 so as to penetrate the restricting member 82. This makes it possible to connect the spaces separated by the restricting member 82 through the inside of the restricting member 82.

[0125] Here, the connecting passage 87 constitutes a lubrication path for the lubricant. In other words, the lubricant can be circulated through the connecting passage 87 of the regulating member 82. This makes it possible to supply a sufficient amount of lubricant to, for example, the crankshafts 7A, 7B, 7C and the crank bearing 42, which are located inside the recess 81, and thus it is easier to obtain sufficient lubrication characteristics.

[0126] Furthermore, as described above, the gear device 1A according to this embodiment is a "distribution type" gear device 1A in which a rotational force as input is applied to the input shaft 500, causing the input shaft 500 to rotate around the rotation axis Ax1, and this rotational force is distributed from the input gear 501 to a plurality of crankshafts 7A, 7B, 7C. In other words, the gear device 1A includes a distribution unit that distributes the rotation of one input gear 501 to a plurality of crankshafts 7A, 7B, 7C via a plurality of crankshaft gears 502A, 502B, 502C. The planetary gear 3 oscillates due to the rotation of the plurality of crankshafts 7A, 7B, 7C.

[0127] Thus, in a gear device 1A having multiple (in this case, three) crankshafts 7A, 7B, and 7C, the support structure for crankshaft 7A described above is applied to all of the multiple crankshafts 7A, 7B, and 7C. In other words, for each of the multiple crankshafts 7A, 7B, and 7C, the regulating member 82 rotatably supports the crankshafts 7A, 7B, and 7C relative to the carrier 19, thereby reducing frictional losses between the crankshafts 7A, 7B, and 7C and the regulating member 82. Therefore, the gear device 1A according to this embodiment has the advantage of easily minimizing power losses.

[0128] Furthermore, for any of the multiple crankshafts 7A, 7B, and 7C, the spaces separated by the restricting member 82 are connected by the connecting passage 87 of the restricting member 82, allowing lubricant to circulate between both sides of the restricting member 82 through the connecting passage 87. As a result, there is the advantage that sufficient lubrication characteristics can be easily obtained.

[0129] By the way, as shown in Figure 10, the rolling elements 822 are not limited to being spherical, but may also be cylindrical or conical, for example. In other words, the regulating member 82 is not limited to a thrust ball bearing having spherical rolling elements 822, but may also be a thrust cylindrical roller bearing having cylindrical rolling elements 822, or a thrust tapered roller bearing having conical rolling elements 822, etc. That is, the rolling elements 822 can be spherical, cylindrical, or conical. As a result, the regulating member 82 can more reliably support the axial load (load in the direction of the axis Ax2).

[0130] Furthermore, the restricting member 82 is not limited to a thrust bearing; as shown in Figure 11, a connecting passage 87 may be formed in a restricting member 82 that is made of a single component, similar to the basic configuration. Figure 11 shows a cross-sectional view of the restricting member 82 (left diagram in Figure 11) and a plan view (right diagram in Figure 11) taken from the direction of the axis Ax2.

[0131] In other words, in the example shown in Figure 11, the restricting member 82 includes a porous portion 820. The communication holes (communication passages 87) are formed in the porous portion 820. In short, if the restricting member 82 is made of a porous material, a large number of voids are formed inside the porous portion 820, and by making each of these voids a communication hole (communication passage 87), it is possible to connect the spaces separated by the restricting member 82 via the communication passages 87.

[0132] Furthermore, the communication passage 87 includes communication grooves 87C formed on the surface of the regulating member 82. In the example shown in Figure 11, multiple communication grooves 87C are formed on the surface of the regulating member 82 facing the crankshafts 7A, 7B, and 7C, extending radially from the axis Ax2. Here, as an example, eight communication grooves 87C are formed at equal intervals (45-degree intervals) in the circumferential direction of the regulating member 82. In this way, the communication passage 87 can also be formed by communication grooves 87C formed on the surface of the regulating member 82.

[0133] Furthermore, it is preferable that the connecting passage 87 has a curved inner surface when viewed from the direction of extension of the connecting passage 87. In other words, if it is a connecting groove 87C, its inner surface, which is the bottom surface and the side surface, may be composed of a continuous curved surface. By including a curved surface on the inner surface of the connecting passage 87, stress concentration on the inner surface of the connecting passage 87 is less likely to occur, and cracks in the regulating member 82 caused by the provision of the connecting passage 87 can be suppressed. In particular, in the case of a connecting groove 87C, if its side surface is a curved surface and is continuous with the surface of the regulating member 82 without any step difference, there is an advantage that friction (snagging) on ​​the surface of the regulating member 82 can be reduced.

[0134] Furthermore, the connecting passage 87 is not limited to a straight path, but may include bends or curves. For example, if the first path 87A extends radially from the crankshafts 7A, 7B, and 7C, it is not limited to a straight path extending straight from the axis Ax2 of the crankshafts 7A, 7B, and 7C, but may also be inclined with respect to the radial direction or curved.

[0135] The configuration of Embodiment 1 (including modified versions) can be adopted in appropriate combination with the various configurations (including modified versions) described in the basic configuration.

[0136] (Embodiment 2) As shown in Figure 12, the internally meshing planetary gear mechanism 1B according to this embodiment (hereinafter also simply referred to as "gear mechanism 1B") differs from the gear mechanism 1A according to Embodiment 1 in the support structure of the crankshafts 7A, 7B, and 7C. Hereinafter, components similar to those in Embodiment 1 will be denoted by common reference numerals and their descriptions will be omitted as appropriate.

[0137] In the gear apparatus 1B according to this embodiment, the multiple (in this case, three) crankshafts 7A, 7B, and 7C have a common configuration, including their support structure. Therefore, in the following description, crankshaft 7A will be used as an example among the multiple crankshafts 7A, 7B, and 7C. Figure 12 is a schematic cross-sectional view of the main part of the gear apparatus 1A (the area corresponding to region Z1 in Figure 4). In Figure 12, the illustration of the bearing device 6 (first main bearing 601 and second main bearing 602) is simplified, and the illustration of the inner ring 61, outer ring 62, and multiple rolling elements 63 is omitted.

[0138] In other words, in the gear apparatus 1B according to this embodiment, the restricting member 82 includes a first restricting member 82A and a second restricting member 82B, which are arranged on both sides of the crankshaft 7A in the axial direction (axis Ax2 direction). The first restricting member 82A is fixed to the carrier 19 and restricts the movement of the crankshaft 7A toward the bottom surface 811 side of the recess 81 of the carrier 19 (left side in Figure 12). The second restricting member 82B is fixed to the carrier 18 and restricts the movement of the crankshaft 7A toward the bottom surface 851 side of the recess 85 of the carrier 18 (right side in Figure 12).

[0139] As a result, the restricting member 82 can restrict the movement of the crankshaft 7A to both sides in the axial direction (axis Ax2 direction). Moreover, both the first restricting member 82A and the second restricting member 82B have rolling elements 822, and the rolling of the rolling elements 822 rotatably supports the crankshaft 7A relative to the carrier 19 (or carrier 18). Therefore, in both the first restricting member 82A and the second restricting member 82B, the loss due to friction between the crankshafts 7A, 7B, 7C and the restricting member 82 can be reduced, which has the advantage of making it easier to keep power loss small.

[0140] More specifically, in the gear apparatus 1B according to this embodiment, the restricting members 82 (first restricting member 82A and second restricting member 82B) include angular contact ball bearings. Specifically, the restricting members 82 (first restricting member 82A and second restricting member 82B) are configured to withstand radial loads, thrust loads (in the direction along the axis Ax2), and bending forces (bending moment loads) relative to the axis Ax2.

[0141] Here, the first restricting member 82A and the second restricting member 82B are arranged on both sides of the crankshaft 7A in a direction parallel to the axis Ax2 (axial direction) relative to the axial center 71, and are facing opposite directions in a direction parallel to the axis Ax2. As an example, the first restricting member 82A and the second restricting member 82B are of a "back-to-back combination type" in which the respective fixed members 823 (outer rings) of the first restricting member 82A and the second restricting member 82B receive a load in the inward thrust direction (direction along the axis Ax2). Furthermore, in the gear device 1B, the first restricting member 82A and the second restricting member 82B are combined in a state in which an appropriate preload is applied to the movable member 824 (inner ring) by tightening them in a direction that brings their respective movable members 824 (inner ring) closer together.

[0142] Furthermore, in the gear apparatus 1B according to this embodiment, the fixing member 823 (outer ring) of the first restricting member 82A is fixed to the carrier 19 by fitting into a step 811A formed on the bottom surface 811 of the recess 81. The fixing member 823 (outer ring) of the second restricting member 82B is fixed to the carrier 18 by fitting into a step formed on the bottom surface 851 of the recess 85. The first restricting member 82A contacts the output side (left side in Figure 12) end face of the rotation axis Ax1 at the axial center 71 of the crankshaft 7A with the movable member 824 (inner ring), thereby restricting the movement of the crankshaft 7A toward the bottom surface 811 side (left side in Figure 12). The second restricting member 82B brings the input side (right side in Figure 12) end face of the rotation axis Ax1 at the axial center 71 of the crankshaft 7A into contact with the movable member 824 (inner ring), thereby restricting the movement of the crankshaft 7A toward the bottom surface 851 side of the recess 85 (right side in Figure 12).

[0143] Furthermore, in the gear apparatus 1B according to this embodiment, as shown in the blown-out in Figure 12, the communication passage 87 includes a second path 87B that extends in the axial direction of the crankshafts 7A, 7B, and 7C. In this embodiment, each of the gaps between the multiple rolling elements 822 in the space between the fixed member 823 as the outer ring and the movable member 824 as the inner ring constitutes a communication passage 87, so the regulating member 82 has multiple second paths 87B that extend in the direction along the axis Ax2. This allows the crankshafts 7A, 7B, and 7C side and the bottom surface 811 side of the recess 81 to be connected from the perspective of the regulating member 82 through the second paths 87B.

[0144] The configuration of Embodiment 2 (including modified examples) can be adopted in appropriate combination with the basic configuration or the various configurations (including modified examples) described in Embodiment 1.

[0145] (Embodiment 3) As shown in Figure 13, the internally meshing planetary gear unit 1C according to this embodiment (hereinafter also simply referred to as "gear unit 1C") differs from the gear unit 1A according to Embodiment 1 in the support structure of the crankshafts 7A, 7B, and 7C. Hereinafter, components similar to those in Embodiment 1 will be denoted by common reference numerals and their descriptions will be omitted as appropriate.

[0146] In the gear apparatus 1C according to this embodiment, the multiple (in this case, three) crankshafts 7A, 7B, and 7C have a common configuration, including their support structure. Therefore, below, we will explain using crankshaft 7A as an example. Figure 13 is a schematic cross-sectional view of the main part of the gear apparatus 1A (the area corresponding to region Z1 in Figure 4). In Figure 13, the illustration of the bearing device 6 (first main bearing 601 and second main bearing 602) is simplified, and the illustration of the inner ring 61, outer ring 62, and multiple rolling elements 63 is omitted.

[0147] In other words, the gear device 1C according to this embodiment includes a crank bearing 42 that rotatably supports the crankshaft 7A within the recess 81. The restricting member 82 restricts the movement of the crankshaft 7A and the crank bearing 42 toward the bottom surface 811 side of the recess 81.

[0148] Specifically, in the gear apparatus 1C according to this embodiment, the retaining ring 83 and washer 84 are omitted. Furthermore, the restricting member 82 restricts the movement of the crankshaft 7A and the crank bearing 42 toward the bottom surface 811 by bringing not only the crankshaft 7A but also the crank bearing 42 into contact with the movable member 824. In short, the restricting member 82 directly restricts the movement of not only the crankshaft 7A but also the crank bearing 42 toward the bottom surface 811.

[0149] More specifically, the restricting member 82 restricts the movement of the multiple rolling elements 402 toward the bottom surface 811, either directly or indirectly (via the retainer 403). This eliminates the need for a structure (retaining ring 83) to restrict the relative movement of the crank bearing 42 with respect to the crankshaft 7A, and allows for the restriction of movement toward the bottom surface 811 for both the crankshaft 7A and the crank bearing 42 with a relatively simple structure.

[0150] Furthermore, in this embodiment, the bottom surface 811 of the recess 81 does not have a step 811A, and the bottom surface 811 is formed flat. Similarly, the inner circumferential surface 812 of the recess 81 does not have a step 812A, and the inner diameter of the inner circumferential surface 812 is uniformly set. However, the configuration is not limited to this, and at least one of the step 811A on the bottom surface 811 and the step 812A on the inner circumferential surface 812 may be formed.

[0151] The configuration of Embodiment 3 (including modified examples) can be adopted in appropriate combination with the basic configuration, and various configurations (including modified examples) described in Embodiment 1 or Embodiment 2.

[0152] (Embodiment 4) As shown in Figure 14, the internally meshing planetary gear unit 1D according to this embodiment (hereinafter also simply referred to as "gear unit 1D") differs from the gear unit 1A according to Embodiment 1 in the support structure of the crankshafts 7A, 7B, and 7C. Hereinafter, components similar to those in Embodiment 1 will be denoted by common reference numerals and their descriptions will be omitted as appropriate.

[0153] In the gear apparatus 1D according to this embodiment, the multiple (in this case, three) crankshafts 7A, 7B, and 7C have a common configuration, including their support structure. Therefore, in the following description, crankshaft 7A will be used as an example among the multiple crankshafts 7A, 7B, and 7C. Figure 14 is a schematic cross-sectional view of the main part of the gear apparatus 1A (the area corresponding to region Z1 in Figure 4). In Figure 14, the illustration of the bearing device 6 (first main bearing 601 and second main bearing 602) is simplified, and the illustration of the inner ring 61, outer ring 62, and multiple rolling elements 63 is omitted.

[0154] In other words, the gear device 1D according to this embodiment further comprises a flange member 86. The flange member 86 is interposed between the restricting member 82 and the crankshaft 7A, and contacts one end face of the crankshaft 7A and rotates together with the crankshaft 7A. In short, in this embodiment, the movable member 824 of the restricting member 82 indirectly contacts the end face of the crankshaft 7A via the flange member 86, thereby restricting the movement of the crankshaft 7A toward the bottom surface 811.

[0155] Specifically, the flange member 86 is a metal part formed in an annular shape. The flange member 86 has an annular shape that is a perfect circle centered on the axis Ax2 in a plan view. The inner diameter of the flange member 86 is the same as the inner diameter of the movable member 824, and the outer diameter of the flange member 86 is the same as the outer diameter of the movable member 824. The flange member 86 is located on the input side of the rotation axis Ax1 (right side in Figure 14) relative to the movable member 824.

[0156] With this configuration, the flange member 86 is rotatably supported relative to the carrier 19 by the rolling of the rolling elements 822 of the regulating member 82, thereby reducing frictional losses between the crankshafts 7A, 7B, 7C and the regulating member 82. As a result, the gear device 1D according to this embodiment has the advantage of easily minimizing power losses.

[0157] Furthermore, in this embodiment, the bottom surface 811 of the recess 81 does not have a step 811A, and the bottom surface 811 is formed flat. Similarly, the inner circumferential surface 812 of the recess 81 does not have a step 812A, and the inner diameter of the inner circumferential surface 812 is uniformly set. However, the configuration is not limited to this, and at least one of the step 811A on the bottom surface 811 and the step 812A on the inner circumferential surface 812 may be formed.

[0158] The configuration of Embodiment 4 (including modified examples) can be appropriately combined with the various configurations (including modified examples) described in the basic configuration, Embodiment 1, Embodiment 2, or Embodiment 3.

[0159] (summary) As described above, the internal meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to the first embodiment comprises an internal gear (2), a planetary gear (3), a crankshaft (7A, 7B, 7C), a carrier (19), and a regulating member (82), and rotates the planetary gear (3) relative to the internal gear (2) by oscillating the planetary gear (3). The internal gear (2) has an annular gear body (22) and a plurality of external pins (23) that are held in a rotatable state in a plurality of internal grooves (223) formed on the inner circumferential surface (221) of the gear body (22) and constitute the internal teeth (21). The planetary gear (3) has external teeth (31) that partially mesh with the internal teeth (21). The crankshafts (7A, 7B, 7C) oscillate the planetary gear (3) by rotating around the axis (Ax2). The carrier (19) has a recess (81) and rotatably supports the crankshafts (7A, 7B, 7C) within the recess (81). The regulating member (82) is positioned within the recess (81) of the carrier (19) so as to face one end face of the crankshafts (7A, 7B, 7C) in the axial direction. By bringing the crankshafts (7A, 7B, 7C) into contact with the regulating member (82), the movement of the crankshafts (7A, 7B, 7C) toward the bottom surface (811) of the recess (81) is restricted. The regulating member (82) has a communication passage (87) that connects the spaces separated by the regulating member (82).

[0160] In this embodiment, the restricting member (82) can restrict the movement of the crankshafts (7A, 7B, 7C) toward the bottom surface (811) of the recess (81) in the axial direction. Here, the spaces separated by the restricting member (82) are connected by the connecting passage (87) of the restricting member (82), so the lubricant can be circulated between both sides of the restricting member (82) through the connecting passage (87). As a result, there is an advantage in that sufficient lubrication characteristics can be easily obtained.

[0161] In the internally meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to the second embodiment, the regulating member (82) has a plurality of connecting passages (87) as in the first embodiment.

[0162] According to this embodiment, compared to the case of a single connecting passage (87), the lubricant can be circulated more easily, and more sufficient lubrication characteristics can be obtained.

[0163] In the internally meshing planetary gear system (1,1A,1B,1C,1D) according to the third embodiment, in the first or second embodiment, the communication passage (87) includes a first path (87A) extending radially with respect to the crankshaft (7A,7B,7C).

[0164] According to this embodiment, spaces separated by the restricting member (82) can be connected through a first path (87A) that extends in the radial direction.

[0165] In the internally meshing planetary gear system (1, 1A, 1B, 1C, 1D) according to the fourth embodiment, in any of the first to third embodiments, the communication passage (87) includes a second path (87B) extending in the axial direction of the crankshaft (7A, 7B, 7C).

[0166] According to this embodiment, the spaces separated by the restricting member (82) can be connected through a second path (87B) that extends in the axial direction.

[0167] In the fifth embodiment of the internally meshing planetary gear device (1, 1A, 1B, 1C, 1D), in any of the first to fourth embodiments, the communication passage (87) includes a communication groove (87C) formed on the surface of the regulating member (82).

[0168] According to this embodiment, the communication passage (87) can also be formed by the communication groove (87C) formed on the surface of the regulating member (82).

[0169] In the internally meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to the sixth embodiment, in any of the first to fifth embodiments, the connecting passage (87) has a curved inner surface when viewed from the direction of extension of the connecting passage (87).

[0170] According to this embodiment, since the inner surface of the connecting passage (87) includes a curved surface, stress concentration is less likely to occur on the inner surface of the connecting passage (87), and cracks in the regulating member (82) caused by the provision of the connecting passage (87) can be suppressed. In particular, in the case of the connecting groove (87C), if its side surface is a curved surface and is continuous with the surface of the regulating member (82) without any step difference, there is the advantage that friction (snagging) on ​​the surface of the regulating member (82) can be reduced.

[0171] The internal meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to the seventh embodiment, in any of the first to sixth embodiments, the communication passage (87) includes a communication hole formed inside the regulating member (82).

[0172] According to this embodiment, the spaces separated by the restricting member (82) can be connected through the inside of the restricting member (82).

[0173] In the internally meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to the eighth embodiment, in any of the first to seventh embodiments, the regulating member (82) includes a porous portion (820). The communication holes are formed in the porous portion (820).

[0174] According to this embodiment, by making the numerous voids present inside the porous portion (820) into communication holes, it is possible to connect the spaces separated by the restricting member (82) via the communication passage (87).

[0175] In the ninth embodiment, the internally meshing planetary gear unit (1, 1A, 1B, 1C, 1D) is configured such that, in any of the first to eight embodiments, the connecting passage (87) constitutes a lubrication passage for a lubricant.

[0176] According to this embodiment, for example, it becomes possible to supply a generous amount of lubricant to the crankshafts (7A, 7B, 7C) and crank bearings (42) located inside the recess (81), making it easier to obtain sufficient lubrication characteristics.

[0177] The internally meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to the tenth embodiment further comprises a distribution unit that distributes the rotation of one input gear (501) to multiple crankshafts (7A, 7B, 7C) via multiple crankshaft gears (502A, 502B, 502C) in any of the first to ninth embodiments. The planetary gear (3) oscillates due to the rotation of the multiple crankshafts (7A, 7B, 7C).

[0178] According to this embodiment, for any of the multiple crankshafts (7A, 7B, 7C), the spaces separated by the restricting member (82) are connected by the connecting passage (87) of the restricting member (82), so that lubricant can be circulated between both sides of the restricting member (82) through the connecting passage (87). As a result, there is an advantage in that sufficient lubrication characteristics can be easily obtained.

[0179] The robot joint device (200) according to the 11th embodiment comprises an internal meshing planetary gear device (1, 1A, 1B, 1C, 1D) according to any of the 1st to 10th embodiments, a first member (201) fixed to the gear body (22), 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).

[0180] This embodiment has the advantage of making it easier to obtain sufficient lubrication characteristics.

[0181] The configurations relating to the 2nd to 10th aspects are not essential to the internally meshing planetary gear system (1, 1A, 1B, 1C, 1D) and can be omitted as appropriate. [Explanation of Symbols]

[0182] 1,1A,1B,1C,1D Internally meshing planetary gear system 2 Internal gear 3 Planetary gears 7A, 7B, 7C crank axle 19 Careers 21 Inner teeth 22 Gear body 23 Outer pin 31 External teeth 42 Crank bearings 81 recess 82 Regulating members 87 Communication path 87A Route 1 87B Second Route 87C Communication groove 200 Robot Joint Devices 201 First Member 202 Second Member 221 Inner surface (of the gear body) 223 Inner circumferential groove 401 Outer ring 402 Rolling element 811 Bottom 820 Porous part Ax2 axis center

Claims

1. An internal gear having an annular gear body and a plurality of external pins that are held in a rotatable state in a plurality of internal grooves formed on the inner surface of the gear body and constitute internal teeth, A planetary gear having external teeth that partially mesh with the internal teeth, A crankshaft that rotates around its axis to cause the planetary gear to oscillate, A carrier having a recess and rotatably supporting the crankshaft within the recess, The carrier comprises a regulating member positioned within the recess so as to face one end face of the crankshaft in the axial direction, By oscillating the planetary gear, the planetary gear is rotated relative to the internal gear, By bringing the crankshaft into contact with the restricting member, the movement of the crankshaft toward the bottom surface of the recess is restricted. The restricting member has a connecting passage that connects the spaces separated by the restricting member. Internally meshing planetary gear system.

2. The regulating member has a plurality of the communication passages, The internal meshing planetary gear device according to claim 1.

3. The aforementioned communication passage includes a first path extending radially in the direction of the crankshaft, The internal meshing planetary gear device according to claim 1 or 2.

4. The aforementioned communication passage includes a second path extending in the axial direction of the crankshaft, The internal meshing planetary gear device according to claim 1 or 2.

5. The communication passage includes a communication groove formed on the surface of the regulating member, The internal meshing planetary gear device according to claim 1 or 2.

6. The aforementioned passage has a curved inner surface when viewed from the direction of extension of the passage. The internal meshing planetary gear device according to claim 1 or 2.

7. The aforementioned communication passage includes a communication hole formed inside the regulating member. The internal meshing planetary gear device according to claim 1 or 2.

8. The regulating member includes a porous portion, The aforementioned communication holes are formed in the porous portion. The internal meshing planetary gear device according to claim 7.

9. The aforementioned connecting passage constitutes a lubrication path for the lubricant, The internal meshing planetary gear device according to claim 1 or 2.

10. The system further includes a distribution unit that distributes the rotation of one input gear to multiple crankshafts via multiple crankshaft gears, The planetary gear oscillates due to the rotation of the plurality of crankshafts. The internal meshing planetary gear device according to claim 1 or 2.

11. An internal meshing planetary gear device according to claim 1 or 2, A first member fixed to the gear body, The system comprises 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, Joint device for robots.

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