Internal meshing planetary gear device and joint device for robot

Abstract

The invention provides an internally engaged planetary gear device and a joint device for a robot, wherein the internally engaged planetary gear device has a relatively simple structure and can restrict axial movement of a crankshaft. An internally engaged planetary gear device (1B) is provided with an internally toothed gear (2), a planetary gear (3), an input-side carrier (18), an output-side carrier (19), a first restriction structure (91), and a second restriction structure (92). The first restricting structure (91) includes an input-side cover (13) mounted on the opposite side of the planetary gear (3) in the axial direction of the input-side carrier (18). The first restricting structure (91) restricts the movement of the crankshaft (7A) toward one side in the axial direction by causing the step part (70) to directly or indirectly contact the input-side cover (13). The second restricting structure (92) restricts the movement of the crankshaft (7A) toward the other side in the axial direction by causing the step section (70) to directly or indirectly contact the output-side carrier (19).

Description

Technical Field

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

[0002] As a related art, there is known an eccentric oscillating type internal meshing planetary gear device called a separation type (see, for example, Patent Document 1). In the related art internal meshing planetary gear device, a plurality of (for example, three) crankshafts are arranged at positions offset from the axis of the internal gear, and each crankshaft is synchronously driven by the crankshaft gear, thereby causing the planetary gear (external gear) to oscillate while being internally meshed with the internal gear.

[0003] The planetary gear includes a first planetary gear and a second planetary gear. A pair of gear racks are arranged on both axial sides of the first planetary gear and the second planetary gear. Each crankshaft is supported on a pair of gear racks via a pair of tapered roller bearings. When the input gear rotates, the three crankshaft gears that are simultaneously meshed with the input gear rotate in the same direction at the same speed. Since the crankshafts are spline-connected to each crankshaft gear, the three crankshafts rotate in the same direction at the same speed in a state where the gear ratio between the input gear and the crankshaft gear is reduced. As a result, the three first eccentric parts formed at the same axial position of the three crankshafts rotate synchronously to cause the first planetary gear to swing, and the three second eccentric parts formed at the same axial position of the three crankshafts rotate synchronously to cause the second planetary gear to swing.

[0004] The first planetary gear and the second planetary gear are respectively internally meshed with the internal gear. The internal gear has a gear body and an outer pin (pin member), and the outer pin (pin member) is rotatably installed in the gear body to form the internal teeth of the internal gear. Here, the number of teeth of the internal gear (the number of roots of the outer pin) is slightly greater than the number of teeth of each planetary gear. Therefore, every time each planetary gear swings once, the circumferential phase deviation (rotation) of the first planetary gear and the second planetary gear relative to the internal gear is an amount corresponding to the difference in the number of teeth, and the rotation is transmitted to a pair of gear racks as the revolution of each crankshaft around the axis (rotation axis) of the internal gear. As a result, a pair of gear racks can be relatively rotated relative to the gear body (the housing integrated with it) around the rotation axis.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-75354 Summary of the invention

[0008] [Problems to be solved by the invention]

[0009] In the above-mentioned related art structure, each crankshaft is supported by a pair of gear carriers via a pair of tapered roller bearings, thereby restricting the movement in the axial direction. Therefore, there is a problem that the structure becomes complicated and it is difficult to achieve miniaturization of the entire device.

[0010] An object of the present disclosure is to provide an internally meshing planetary gear device and a robot joint device that can restrict the axial movement of a crankshaft despite having a relatively simple structure.

[0011] [Technical means to solve the problem]

[0012] An internally meshing planetary gear device of one form disclosed in the present invention comprises an internal gear, planetary gears, a crankshaft, an input side gear frame and an output side gear frame, and the planetary gears are made to rotate relative to the internal gear by swinging the planetary gears. The internal gear has an annular gear body and a plurality of outer pins, and the plurality of outer pins are held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a rotatable state and constitute internal teeth. The planetary gears have outer teeth partially meshed with the internal teeth. The crankshaft has step portions at at least two locations along the axial direction of the axis, and the planetary gears are made to swing by rotating around the axis. The input side gear frame and the output side gear frame are arranged on both sides of the axial direction of the planetary gears, and rotatably support the crankshaft. The internally meshing planetary gear device also comprises a first limiting structure and a second limiting structure. The first limiting structure comprises an input side cover mounted on the axial side of the input side gear frame on the opposite side of the planetary gears. The first limiting structure limits the movement of the crankshaft toward one axial side by making the step portion directly or indirectly contact the input side cover. The second limiting structure limits the movement of the crankshaft toward the other axial side by making the step portion directly or indirectly contact the output side gear carrier.

[0013] A robot joint device according to one aspect of the present disclosure includes: the internally meshing planetary gear device; a first member fixed to the gear body; and a second member that rotates relative to the first member as the planetary gear rotates relative to the internal gear.

[0014] [Effects of the Invention]

[0015] According to the present disclosure, it is possible to provide an internally meshing planetary gear device and a robot joint device that can suppress axial movement of a crankshaft despite having a relatively simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is a perspective view showing a schematic structure of an actuator including an internally meshing planetary gear device having a basic structure.

[0017] Figure 2 This is a schematic exploded perspective view of the internally meshing planetary gear device as viewed from the input side of the rotating shaft.

[0018] Figure 3 This is a schematic exploded perspective view of the internally meshing planetary gear device as viewed from the output side of the rotating shaft.

[0019] Figure 4 It is a schematic cross-sectional view of the internally meshing planetary gear device.

[0020] Figure 5 represents the internal meshing planetary gear device, Figure 4 A1-A1 line cross-sectional view.

[0021] Figure 6 represents the internal meshing planetary gear device, Figure 4 B1-B1 line cross-sectional view.

[0022] Figure 7 1 is a schematic cross-sectional view of an internally meshing planetary gear device according to Reference Example 1.

[0023] Figure 8 This is a schematic diagram of the internally meshing planetary gear device as viewed from the output side of the rotating shaft.

[0024] Fig. 9 It is a schematic perspective view showing the structure of the crankshaft and its surroundings of the internally meshing planetary gear device.

[0025] Fig.10 It is a schematic exploded perspective view showing the structure of the crankshaft and its surroundings of the internally meshing planetary gear device.

[0026] Fig.11 It is a schematic perspective view showing a crankshaft of the internally meshing planetary gear device.

[0027] Fig.12 The main part of the internal meshing planetary gear device is Figure 7 Schematic enlarged view of area Z1.

[0028] Fig.13 The main part of the internal meshing planetary gear device is Figure 7 A schematic enlarged view of area Z2.

[0029] Fig.14 The main part of the internal meshing planetary gear device is Fig.13 Schematic enlarged view of area Z1.

[0030] Fig.15 This is a schematic diagram showing a robot joint device using the internal meshing planetary gear device.

[0031] Fig.16 This is a schematic cross-sectional view of the internally meshing planetary gear device according to the first embodiment.

[0032] Fig.17 The main part of the internal meshing planetary gear device is Fig.16 Schematic enlarged view of area Z1. DETAILED DESCRIPTION

[0033] (Basic structure)

[0034] (1) Summary

[0035] For an overview of the internally meshing planetary gear device 1 of the basic structure, refer to Figure 1 to Figure 4 The drawings referred to in this disclosure are schematic drawings, and the size and thickness ratios of the components in the drawings do not necessarily reflect the actual size ratios. For example, Figure 1 to Figure 4 The tooth shapes, sizes, and numbers of teeth of the internal teeth 21 and the external teeth 31 are schematically shown for the purpose of explanation only and are not intended to be limited to the shapes shown in the figure.

[0036] The internal meshing planetary gear device 1 of this basic structure (hereinafter also referred to as "gear device 1") is a gear device having 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 the planetary gear 3 is rotated relative to the internal gear 2 by swinging the planetary gear 3. In addition, the internal meshing planetary gear device 1 also has a bearing member 6 having an outer wheel 62 and an inner wheel 61. The inner wheel 61 is arranged inside the outer wheel 62 and is supported so as to be relatively rotatable relative to the outer wheel 62. In particular, the gear device 1 of this basic structure is an eccentric swing type internal meshing planetary gear device called a separation type.

[0037] The gear device 1 of the basic structure is as follows Figure 1 to Figure 4As shown, the gear device 1 includes a plurality of (three in the basic structure) crankshafts (eccentric shafts) 7A, 7B, and 7C arranged at positions offset from the axis (rotation axis Ax1) of the internal gear 2. Furthermore, the gear device 1 includes: an input shaft 500 arranged on the axis (rotation axis Ax1) of the internal gear 2 and centered on the rotation axis Ax1; and an input gear 501 formed integrally with the input shaft 500. Crankshaft gears 502A, 502B, and 502C are spline-connected to the plurality of crankshafts 7A, 7B, and 7C, respectively. These plurality of (three in the basic structure) crankshaft gears 502A, 502B, and 502C are arranged in a manner meshing with the input gear 501. Therefore, when the input shaft 500 is driven, the gear device 1 synchronously drives the crankshafts 7A, 7B, and 7C through the input gear 501, thereby causing the planetary gear 3 to oscillate.

[0038] The internal gear 2 has internal teeth 21 and is fixed to the outer wheel 62. In particular, in this basic structure, 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 circumferential 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 partially meshed with the internal teeth 21. That is, on the inner side of the internal gear 2, the planetary gear 3 is inscribed relative to the internal gear 2, and a portion of the external teeth 31 is in meshed with a portion of the internal teeth 21. In this state, when the plurality of crankshafts 7A, 7B, and 7C are driven, the planetary gear 3 swings, and the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2, and a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated 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 will rotate (rotate) with the relative rotation of the two gears. As a result, the planetary gear 3 obtains a rotation output that is reduced in speed at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

[0039] This type of gear device 1 is used to derive the rotation equivalent to the self-rotation component of the planetary gear 3 as the rotation of a pair of gear carriers 18 and 19 integrated with the inner wheel 61 of the bearing member 6. Therefore, the gear device 1 uses the input shaft 500 as the input side and the pair of gear carriers 18 and 19 as the output side, and functions as a gear device with a relatively high reduction ratio. Therefore, in the gear device 1 of this basic structure, in order to transmit the rotation equivalent to the self-rotation component of the planetary gear 3 to the pair of gear carriers 18 and 19, a plurality of crankshafts 7A, 7B, and 7C are supported by a pair of gear carriers 18 and 19. The pair of gear carriers 18 and 19 are arranged on both sides of the axial direction (along the direction of the rotation axis Ax1) of the planetary gear 3, and rotatably support each crankshaft 7A, 7B, and 7C.

[0040] Here, the plurality of crankshafts 7A, 7B, 7C rotates relative to the internal gear 2 with the rotation of the planetary gear 3 while being inserted into the plurality of openings 33 formed in the planetary gear 3. Each crankshaft 7A, 7B, 7C has a shaft center portion 71 and an eccentric portion 72 eccentric to the shaft center portion 71. A pair of gear carriers 18, 19 rotatably supports the shaft center portion 71 of each crankshaft 7A, 7B, 7C, and the eccentric portion 72 of each crankshaft 7A, 7B, 7C is inserted into the opening 33 of the planetary gear 3. Therefore, the swing component of the planetary gear 3, that is, the revolution component of the planetary gear 3 is absorbed by the revolution component of the eccentric portion 72 to the shaft center portion 71. In other words, the eccentric portion 72 of the shaft center portion 71 of each crankshaft 7A, 7B, 7C rotates in a manner of orbiting relative to the shaft center portion 71, thereby absorbing the swing component of the planetary gear 3. Therefore, the rotation (autorotation component) of the planetary gear 3 in addition to the oscillation component (revolution component) of the planetary gear 3 is transmitted to the pair of carriers 18 and 19 via the plurality of crankshafts 7A, 7B, and 7C.

[0041] Moreover, the gear device 1 of the basic structure is as follows Figure 1 As shown, the actuator 100 is constituted together with the driving source 101. In other words, the actuator 100 of this basic structure includes the gear device 1 and the driving source 101. The driving source 101 generates a driving force for swinging the planetary gear 3. Specifically, the driving source 101 swings the planetary gear 3 by rotating the input shaft 500 around the rotation axis Ax1.

[0042] (2) Definition

[0043] The term "ring-shaped" as used in the present disclosure refers to a shape such as a circle (loop) that forms a space (region) enclosed inside at least when viewed from above, and is not limited to a circular shape (ring-shaped) that is a perfect circle when viewed from above, and may be, for example, an elliptical shape or a polygonal shape, etc. Furthermore, even a shape having a bottom such as a cup-shaped shape is also included in the term "ring-shaped" as long as its peripheral wall is ring-shaped.

[0044] The term "revolution" as used in this disclosure refers to the rotation of an object around a rotation axis other than the central axis passing through the center (center of gravity) of the object. When an object revolves, the center of the object moves along a revolving orbit centered on the rotation axis. Therefore, for example, when an object revolves around an eccentric axis parallel to the central axis passing through the center (center of gravity) of the object, the object revolves around the eccentric axis as the rotation axis. As an example, the planetary gear 3 revolves around the rotation axis Ax1 in the internal gear 2 by swinging.

[0045] In addition, in the present disclosure, one side ( Figure 4 The left side of the rotation axis Ax1 is called the “output side”, and the other side of the rotation axis Ax1 ( Figure 4The right side of the input is called the “input side”. Figure 4 In the example, the input shaft 500 is rotated from the "input side" of the rotation axis Ax1, and the rotation of the pair of gear carriers 18 and 19 is derived from the "output side" of the rotation axis Ax1. However, the "input side" and "output side" are merely labels for explanation, and are not intended to limit the positional relationship between the input and output as viewed from the gear device 1.

[0046] The "rotation axis" referred to in the present disclosure refers to a virtual axis (straight line) that is the rotation center of a rotating body. That is, the rotation axis Ax1 is a virtual axis without a physical body. The input shaft 500 rotates around the rotation axis Ax1.

[0047] The "internal teeth" and "external teeth" mentioned in this disclosure are not single "teeth" but a collection (group) of multiple "teeth". That is, the internal teeth 21 of the internal gear 2 includes a collection of multiple teeth arranged on the inner peripheral surface 221 of the internal gear 2 (gear body 22). Similarly, the external teeth 31 of the planetary gear 3 includes a collection of multiple teeth arranged on the outer peripheral surface of the planetary gear 3.

[0048] (3) Structure

[0049] For details on the structure of the internally meshing planetary gear device 1 of the basic structure, refer to Figure 1 to Figure 6 to explain.

[0050] Figure 1 It is a perspective view showing a schematic structure of an actuator 100 including the gear device 1 . Figure 1 The driving source 101 is schematically shown in FIG. Figure 2 It is a schematic exploded perspective view of the gear device 1 as viewed from the input side of the rotation axis Ax1. Figure 3 This is a schematic exploded perspective view of the gear device 1 as viewed from the output side of the rotation axis Ax1. Figure 4 It is a schematic cross-sectional view of the gear device 1 . Figure 5 yes Figure 4 A1-A1 line cross-sectional view. Figure 6 yes Figure 4 However, Figure 5 and Figure 6 In the figure, although it is a cross section, hatching is omitted for parts other than the crankshafts 7A, 7B, and 7C.

[0051] (3.1) Overall structure

[0052] The gear device 1 of the basic structure is as follows Figure 1 to Figure 4As shown, it is provided with an internal gear 2, a planetary gear 3, a bearing member 6, a plurality of crankshafts 7A, 7B, 7C, a pair of gear carriers 18, 19 and an input shaft 500. Moreover, in this basic structure, the gear device 1 also includes an input gear 501, a plurality of crankshaft gears 502A, 502B, 502C, a pair of roller bearings 41, 42, an eccentric bearing 5 and a housing 10. In this basic structure, the internal gear 2, the planetary gear 3, the plurality of crankshafts 7A, 7B, 7C and a pair of gear carriers 18, 19, etc., which are components of the gear device 1, are made of stainless steel, cast iron, carbon steel for mechanical structure, chrome-molybdenum steel, metals such as phosphor bronze or aluminum bronze, or light metals such as aluminum or titanium. The metal (including light metal) mentioned here includes metals subjected to surface treatment such as nitriding treatment.

[0053] In the present basic structure, an inscribed planetary gear device using a trochoid tooth profile is exemplified as an example of the gear device 1. That is, the gear device 1 of the present basic structure includes an inscribed planetary gear 3 having a trochoid tooth profile.

[0054] In addition, in this basic structure, as an example, the gear device 1 is used in a state where the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 are fixed to a fixed member such as a housing 10. Thus, along with the relative rotation of the internal gear 2 and the planetary gear 3, the planetary gear 3 will rotate relative to the fixed member (housing 10, etc.).

[0055] Furthermore, in this basic structure, when the gear device 1 is used for the actuator 100, a rotational force as an input is applied to the input shaft 500, and a rotational force as an output is derived from the pair of gear carriers 18 and 19 integrated with the inner ring 61 of the bearing member 6. That is, the gear device 1 operates by using the rotation of the input shaft 500 as an input rotation and the rotation of the pair of gear carriers 18 and 19 integrated with the inner ring 61 as an output rotation. As a result, in the gear device 1, an output rotation that is reduced in speed at a relatively high reduction ratio relative to the input rotation is obtained.

[0056] The driving source 101 is a power generating source such as a motor (electric motor). The power generated by the driving source 101 is transmitted to the input shaft 500 in the gear device 1. Specifically, the driving source 101 is connected to the input shaft 500, and the power generated by the driving source 101 is transmitted to the input shaft 500. Thus, the driving source 101 can rotate the input shaft 500.

[0057] Furthermore, in the gear device 1 of this basic structure, as Figure 4As shown, the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are located on the same straight line. In other words, the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are coaxial. Here, the rotation axis Ax1 on the input side is the rotation center of the input shaft 500 to which the input rotation is given, and the rotation axis Ax1 on the output side is the rotation center of the inner wheel 61 (and a pair of gear racks 18, 19) that generates the output rotation. That is, in the gear device 1, an output rotation that is decelerated at a relatively high reduction ratio on the same axis relative to the input rotation will be obtained.

[0058] Internal gear 2 Figure 5 and Figure 6 As shown, it is an annular part having internal teeth 21. In this basic structure, the internal gear 2 has an annular shape whose at least inner circumference is a perfect circle when viewed from above. On the inner circumference of the annular internal gear 2, internal teeth 21 are formed along the circumferential direction of the internal gear 2. The multiple teeth constituting the internal teeth 21 are all of the same shape and are arranged at equal pitches in the entire area of ​​the circumferential direction of the inner circumferential surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 is a perfect circle when viewed from above. The center of the pitch circle of the internal teeth 21 is located on the rotation axis Ax1. Moreover, the internal gear 2 has a specified thickness in the direction of the rotation axis Ax1. The tooth lines of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth line direction is slightly smaller than that in the thickness direction of the internal gear 2.

[0059] Here, as described above, the internal gear 2 has an annular (ring-shaped) gear body 22 and a plurality of outer pins 23. The plurality of outer pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state and constitute the internal teeth 21. In other words, the plurality of outer pins 23 function as a plurality of teeth constituting the internal teeth 21. Specifically, on the inner circumferential surface 221 of the gear body 22, as shown in FIG. Figure 2 As shown, a plurality of inner circumferential grooves 223 are formed in the entire area in the circumferential direction. The plurality of inner circumferential grooves 223 are all of the same shape and are arranged at equal pitches. The plurality of inner circumferential 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 outer pins 23 are assembled to the gear body 22 in a manner of being embedded in the plurality of inner circumferential grooves 223. The plurality of outer pins 23 are each held in a rotatable state in the inner circumferential grooves 223. Moreover, the gear body 22 (together with the outer wheel 62) is fixed to the housing 10. Furthermore, a plurality of fixing holes 222 for fixing are formed in the gear body 22 (refer to Figure 5 ).

[0060] Planetary gear 3 Figure 5 and Figure 6As shown, it is an annular part having external teeth 31. In this basic structure, the planetary gear 3 has an annular shape whose at least outer peripheral surface is a perfect circle when viewed from above. On the outer peripheral surface of the annular planetary gear 3, external teeth 31 are formed along the circumferential direction of the planetary gear 3. The multiple teeth constituting the external teeth 31 are all of the same shape and are arranged at equal pitches in the entire area of ​​the circumferential direction of the outer peripheral surface of the planetary gear 3. That is, the pitch circle of the external teeth 31 is a perfect circle when viewed from above. Moreover, the planetary gear 3 has a prescribed thickness in the direction of the rotation axis Ax1. The external teeth 31 are all formed over the entire length of the planetary gear 3 in the thickness direction. The tooth lines 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 formed integrally with the metal component that is one with the body of the planetary gear 3.

[0061] Moreover, the gear device 1 of this basic structure has a plurality of planetary gears 3. Specifically, the gear device 1 has two planetary gears 3, namely a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged in a manner facing each other in a direction parallel to the rotation axis Ax1. That is, the planetary gear 3 includes the first planetary gear 301 and the second planetary gear 302 arranged in a direction (axial direction) parallel to the rotation axis Ax1. The shapes of the first planetary gear 301 and the second planetary gear 302 are the same.

[0062] The two planetary gears 3 (the first planetary gear 301 and the second planetary gear 302 ) are arranged with a phase difference of 180 degrees around the rotation axis Ax1 . Figure 4 In the example of FIG. 1 , the first planetary gear 301 and the second planetary gear 302 located on the input side ( Figure 4 The center C1 of the first planetary gear 301 (the center of the pitch circle of the external tooth 31) is in a state of being deviated (biased) upward in the figure relative to the rotation axis Ax1. On the other hand, the output side ( Figure 4 The center C2 of the second planetary gear 302 (on the left side of the figure) (the center of the pitch circle of the external teeth 31) is in a state of being deviated (biased) toward the bottom of the figure relative to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 becomes the eccentricity of the first planetary gear 301 relative to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 becomes the eccentricity of the second planetary gear 302 relative to the rotation axis Ax1. In this way, the plurality of planetary gears 3 are evenly arranged in the circumferential direction centered on the rotation axis Ax1, thereby achieving a balance between the weight and load of the plurality of planetary gears 3.

[0063] The centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are located 180 degrees rotationally symmetrically with respect to the rotation axis Ax1. In this basic structure, the eccentricity ΔL1 and the eccentricity ΔL2 are opposite in direction when viewed from the rotation axis Ax1, but have the same absolute value.

[0064] More specifically, each of the crankshafts 7A, 7B, and 7C has two eccentric portions 72 with respect to one axial portion 71. The eccentricity ΔL0 (see Figure 5 and Figure 6 ) are respectively the same as the eccentricities ΔL1 and ΔL2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation axis Ax1. The shapes of the plurality of crankshafts 7A, 7B, and 7C are the same. The shapes of the plurality of crankshaft gears 502A, 502B, and 502C are also the same.

[0065] Furthermore, a pair of gear carriers 18 and 19 are arranged on both sides of the direction (axial direction) parallel to the rotation axis Ax1 of the first planetary gear 301 and the second planetary gear 302. When the pair of gear carriers 18 and 19 are distinguished from each other, the input side ( Figure 4 The gear carrier 18 on the output side (right side in the figure) of the rotation axis Ax1 is referred to as the "input side gear carrier 18". Figure 4 The gear frame 19 (left side in the figure) is called the "output side gear frame 19". The two ends of each crankshaft 7A, 7B, 7C are held by a pair of gear frames 18 and 19 via roller bearings 41 and 42. That is, each crankshaft 7A, 7B, 7C is held by the input side gear frame 18 and the output side gear frame 19 in a rotatable state on both sides of the direction (axial direction) parallel to the rotation axis Ax1 with respect to the planetary gear 3.

[0066] The eccentric body bearing 5 is mounted on the eccentric portion 72 of each crankshaft 7A, 7B, 7C. Three openings 33 corresponding to the three crankshafts 7A, 7B, 7C are formed in the first planetary gear 301 and the second planetary gear 302, respectively. And the eccentric body bearing 5 is accommodated in each opening 33. In other words, the eccentric body bearing 5 is mounted on the first planetary gear 301 and the second planetary gear 302, respectively, and the eccentric body bearing 5 and the crankshafts 7A, 7B, 7C are inserted into the eccentric body bearing 5, so that the eccentric body bearing 5 and the crankshafts 7A, 7B, 7C are assembled to the planetary gear 3. In the state where the eccentric body bearing 5 and the crankshafts 7A, 7B, 7C are assembled to the planetary gear 3, when the crankshafts 7A, 7B, 7C rotate, the planetary gear 3 swings around the rotation axis Ax1.

[0067] According to the structure described above, the input shaft 500 is rotated around the rotation axis Ax1 by applying a rotation force as an input to the input shaft 500, and the rotation force is distributed from the input gear 501 to the plurality of crankshafts 7A, 7B, and 7C. That is, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that are simultaneously meshed with the input gear 501 rotate in the same direction at the same speed. The crankshafts 7A, 7B, and 7C are spline-connected to the crankshaft gears 502A, 502B, and 502C, so the three crankshafts 7A, 7B, and 7C rotate in the same direction at the same speed while being decelerated by the gear ratio between the input gear 501 and the crankshaft gears 502A, 502B, and 502C. As a result, the three eccentric portions 72 formed at the same position on the input side of the rotation axis Ax1 in the three crankshafts 7A, 7B, and 7C rotate synchronously to cause 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 in the three crankshafts 7A, 7B, and 7C rotate synchronously to cause the second planetary gear 302 to oscillate.

[0068] Figure 5 and Figure 6 The states of the first planetary gear 301 and the second planetary gear 302 at a certain point in time are shown. Figure 5 yes Figure 4 The A1 - A1 line sectional view shows the first planetary gear 301 . Figure 6 yes Figure 4 The cross-sectional view taken along the line B1-B1 shows the second planetary gear 302. Figure 5 and Figure 6 As shown, in the first planetary gear 301 and the second planetary gear 302, the centers C1 and C2 are located at positions that are approximately 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In this basic structure, the eccentricity ΔL1 and the eccentricity ΔL2 are opposite in direction when viewed from the rotation axis Ax1, but their absolute values ​​are approximately the same (both are eccentricity ΔL0). According to the structure, the first planetary gear 301 and the second planetary gear 302 rotate around the rotation axis Ax1 with a phase difference of approximately 180 degrees (eccentric motion) around the rotation axis Ax1 by rotating (rotating) the axial portion 71 around the axis Ax2. In addition, the plurality of planetary gears 3 are arranged approximately evenly in the circumferential direction centered on the rotation axis Ax1, thereby achieving a balance between the weight and load of the plurality of planetary gears 3.

[0069] The planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) configured in this way are arranged on the inner side of the internal gear 2. When viewed from above, the planetary gears 3 are formed to be one size smaller than the internal gear 2, and the planetary gears 3 can swing on the inner side of the internal gear 2 when combined with the internal gear 2. Here, the outer teeth 31 are formed on the outer peripheral surface of the planetary gear 3, and the inner teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gears 3 are arranged on the inner side of the internal gear 2, the outer teeth 31 and the inner teeth 21 face each other.

[0070] Furthermore, the pitch circle of the external teeth 31 is one circle smaller than the pitch circle of the internal teeth 21. Furthermore, 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 position offset by a distance ΔL1 from the center (rotation axis Ax1) of the pitch circle of the internal teeth 21. 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 position offset by a distance ΔL2 from the center (rotation axis Ax1) of the pitch circle of the internal teeth 21.

[0071] Therefore, in either the first planetary gear 301 or the second planetary gear 302, the outer teeth 31 and the inner teeth 21 are at least partially facing each other with a gap therebetween. If the difference in the number of teeth between the outer teeth 31 and the inner teeth 21 is greater than "2", the entire circumferential direction will not mesh with each other. However, the planetary gear 3 swings (revolves) around the rotation axis Ax1 inside the internal gear 2, so the outer teeth 31 and the inner teeth 21 will partially mesh. That is, by the planetary gear 3 (the first planetary gear 301 and the second planetary gear 302) swinging around the rotation axis Ax1, Figure 5 and Figure 6 As shown, a part of the plurality of teeth constituting the external teeth 31 meshes with a part of the plurality of teeth constituting the internal teeth 21. As a result, in the gear device 1, a part of the external teeth 31 can mesh with a part of the internal teeth 21.

[0072] Here, the number of teeth of the internal teeth 21 in the internal gear 2 is N (N is a positive integer) greater than the number of teeth of the external teeth 31 of the planetary gear 3. In this basic structure, as an example, N is "2", and the number of teeth (of the external teeth 31) of the planetary gear 3 is "2" less than the number of teeth (of the internal teeth 21) of the internal gear 2. This difference in the number of teeth between the planetary gear 3 and the internal gear 2 determines the reduction ratio of the output rotation relative to the input rotation in the gear device 1.

[0073] In addition, in this basic structure, as an example, the thickness of the first planetary gear 301 and the second planetary gear 302 combined is made smaller than the thickness of the gear body 22 in the internal gear 2. Furthermore, the dimension of the tooth line direction (direction parallel to the rotation axis Ax1) of the external teeth 31 of the first planetary gear 301 and the second planetary gear 302 combined is made smaller than the dimension of the tooth line direction (direction parallel to the rotation axis Ax1) of the internal teeth 21. In other words, in the direction parallel to the rotation axis Ax1, the external teeth 31 of the first planetary gear 301 and the second planetary gear 302 will converge within the tooth line range of the internal teeth 21.

[0074] Here, the first planetary gear 301 and the second planetary gear 302 are respectively meshed with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 swing once, the first planetary gear 301 and the second planetary gear 302 will rotate with a phase deviation in the circumferential direction corresponding to the difference in the number of teeth (between the internal teeth 21 and the external teeth 31) relative to the internal gear 2. This rotation is transmitted to the pair of gear carriers 18 and 19 as the revolution of each crankshaft 7A, 7B, 7C around the axis (rotation axis Ax1) of the internal gear 2. As a result, the pair of gear carriers 18 and 19 can be relatively rotated with respect to the gear body (the housing 10 integrated therewith) around the rotation axis Ax1.

[0075] In summary, the gear device 1 of this basic structure causes the planetary gear 3 to oscillate by using a plurality of crankshafts 7A, 7B, and 7C arranged at positions offset from the rotation axis Ax1, and obtains a rotation output by utilizing the oscillation of the planetary gear 3. That is, in the gear device 1, when the planetary gear 3 oscillates and the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated 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 will rotate (rotate) along with the relative rotation of the two gears. As a result, a rotation output that is reduced in speed at a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears is obtained from the planetary gear 3.

[0076] The bearing member 6 has an outer ring 62 and an inner ring 61, and is a component for extracting the output of the gear device 1 as the rotation of the inner ring 61 relative to the outer ring 62. In addition to the outer ring 62 and the inner ring 61, the bearing member 6 also has a plurality of rotating bodies 63 (see Figure 4 ). The outer wheel 62 and the inner wheel 61 are both annular parts. The outer wheel 62 and the inner wheel 61 are both annular in shape, which is a perfect circle when viewed from above. The inner wheel 61 is one circle smaller than the outer wheel 62 and is arranged on the inner side of the outer wheel 62. Here, since the inner diameter of the outer wheel 62 is larger than the outer diameter of the inner wheel 61, a gap is generated between the inner peripheral surface of the outer wheel 62 and the outer peripheral surface of the inner wheel 61.

[0077] The plurality of rotating bodies 63 are arranged in the gap between the outer wheel 62 and the inner wheel 61. The plurality of rotating bodies 63 are arranged in a row along the circumferential direction of the outer wheel 62. The plurality of rotating bodies 63 are all metal parts of the same shape and are arranged at equal pitches over the entire area of ​​the circumferential direction of the outer wheel 62.

[0078] More specifically, in the gear device 1 of the basic structure, the bearing member 6 includes a first bearing member 601 and a second bearing member 602. The first bearing member 601 and the second bearing member 602 each include an angular contact ball bearing. Figure 4 As shown, when viewed from the planetary gear 3, it is the input side of the rotation axis Ax1 ( Figure 4 The first bearing member 601 is arranged on the right side of the planetary gear 3 and is the output side ( Figure 4 The bearing member 6 is configured to withstand the load in the radial direction, the load in the thrust direction (along the rotation axis Ax1), and the bending force (bending moment load) relative to the rotation axis Ax1 by means of the first bearing member 601 and the second bearing member 602.

[0079] Here, the first bearing member 601 and the second bearing member 602 are arranged opposite to each other in a direction parallel to the rotation axis Ax1 on both sides (axial direction) of the planetary gear 3. That is, the bearing member 6 is a "combined angular contact ball bearing" formed by combining multiple (here, 2) angular contact ball bearings. Here, as an example, the first bearing member 601 and the second bearing member 602 are "back-side combination type" that bear the load in the thrust direction (along the direction of the rotation axis Ax1) in the direction in which the respective inner wheels 61 approach each other. Furthermore, in the gear device 1, the first bearing member 601 and the second bearing member 602 are combined in a state in which appropriate preload is applied to the inner wheels 61 by tightening them in a direction in which the respective inner wheels 61 approach each other.

[0080] In the gear device 1 of the basic structure, the input side gear carrier 18 and the output side gear carrier 19 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and the planetary gear 3 is connected to the input side gear carrier 18 and the output side gear carrier 19 through the gear carrier hole 34 (see Figure 4 ) are combined with each other. Specifically, Figure 4 As shown, on the input side ( Figure 4 The input side gear carrier 18 is configured on the right side of the planetary gear 3, and the output side ( Figure 4The output side gear frame 19 is configured on the left side of the bearing assembly 6 (the first bearing assembly 601 and the second bearing assembly 602). The inner wheel 61 of the bearing assembly 6 (each of the first bearing assembly 601 and the second bearing assembly 602) is fixed relative to the input side gear frame 18 and the output side gear frame 19. In this basic structure, as an example, the inner wheel of the first bearing assembly 601 is seamlessly integrated with the input side gear frame 18. Similarly, the inner wheel of the second bearing assembly 602 is seamlessly integrated with the output side gear frame 19.

[0081] The output side gear carrier 19 has a plurality of (three, for example) gear carrier pins 191 (see FIG. 1 ) protruding from one surface of the output side gear carrier 19 toward the input side of the rotation axis Ax1. Figure 2 ). These multiple carrier pins 191 are respectively inserted into multiple (three, for example) carrier holes 34 formed in the planetary gear 3, and their front ends are connected by carrier bolts 192 (see FIG. Figure 7 ) is fixed to the input side gear frame 18. Here, a gap is ensured between the gear frame pin 191 and the inner circumference of the gear frame hole 34, and the gear frame pin 191 can move in the gear frame hole 34, that is, it can move relatively with respect to the center of the gear frame hole 34. Therefore, when the planetary gear 3 swings, the gear frame pin 191 will not contact the inner circumference of the gear frame hole 34.

[0082] With the above structure, the gear device 1 is used to derive the rotation corresponding to the rotation component of the planetary gear 3 as the rotation of the input side gear frame 18 and the output side gear frame 19 integrated with the inner wheel 61 of the bearing member 6. That is, in this basic structure, the relative rotation between the planetary gear 3 and the internal gear 2 is derived from the input side gear frame 18 and the output side gear frame 19. In this basic structure, as an example, the gear device 1 is an outer wheel 62 (refer to Figure 4 ) is used in a state where it is fixed to the housing 10 as a fixed member. That is, the planetary gear 3 is connected to the input side gear frame 18 and the output side gear frame 19 as rotating members by using multiple crankshafts 7A, 7B, and 7C, and the gear body 22 is fixed to the fixed member, so that the relative rotation between the planetary gear 3 and the internal gear 2 is derived from the rotating member (the input side gear frame 18 and the output side gear frame 19). In other words, in this basic structure, when the planetary gear 3 rotates relative to the gear body 22, the rotational force of the input side gear frame 18 and the output side gear frame 19 is derived as output.

[0083] Furthermore, in this basic structure, the housing 10 is seamlessly integrated with the gear body 22 of the internal gear 2. That is, the gear body 22 as a fixed member is seamlessly continuous with the housing 10 in a direction parallel to the rotation axis Ax1.

[0084] In more detail, the housing 10 is cylindrical and constitutes the outer contour of the gear device 1. In this basic structure, the central axis of the cylindrical housing 10 is configured to be consistent with the rotation axis Ax1. That is, at least the outer peripheral surface of the housing 10 is a perfect circle centered on the rotation axis Ax1 when viewed from above (when viewed from one side in the axial direction). The housing 10 is formed into a cylindrical shape with both end faces open in the axial direction. Here, the gear body 22 of the internal gear 2 is seamlessly integrated with the housing 10, and the housing 10 and the gear body 22 are treated as one part. Therefore, the inner peripheral surface of the housing 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, the outer wheel 62 of the bearing member 6 is fixed to the housing 10. That is, the outer wheel 62 of the first bearing member 601 is fixed to the input side (the input side) of the inner peripheral surface of the housing 10 which is the rotation axis Ax1 as viewed from the gear body 22 by being embedded. Figure 4 On the other hand, the outer ring 62 of the second bearing member 602 is fixed by embedding to the output side (ie, the output side of the inner peripheral surface of the housing 10, which is the rotation axis Ax1 as viewed from the gear body 22) Figure 4 on the left side of the ).

[0085] Furthermore, the input side ( Figure 4 The end face of the right side of the housing 10 is closed by the input side gear frame 18, and the output side of the rotating shaft Ax1 in the housing 10 ( Figure 4 The end face of the left side of the output side gear frame 19 is closed. Figure 4 As shown, in the space surrounded by the housing 10, the input side gear frame 18 and the output side gear frame 19, parts such as the planetary gears 3 (the first planetary gear 301 and the second planetary gear 302), a plurality of outer pins 23 and the eccentric body bearing 5 are accommodated.

[0086] Multiple (3 in the basic structure) crankshafts 7A, 7B, and 7C each have an axial portion 71 and two eccentric portions 72. The axial portion 71 has a cylindrical shape in which at least the outer peripheral surface is a perfect circle when viewed from above. The center of the axial portion 71, i.e., the axis Ax2, 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 an imaginary circle centered on the rotation axis Ax1. Each eccentric portion 72 has a disk shape in which at least the outer peripheral surface is a perfect circle when viewed from above. The center (central axis) C0 of each eccentric portion 72 is arranged at a position parallel to the rotation axis Ax1 and deviated radially from the rotation axis Ax1. Here, the distance ΔL0 (refer to Figure 5 and Figure 6) becomes the eccentricity of the eccentric portion 72 relative to the axial portion 71. The eccentric portion 72 is in the shape of a flange that protrudes from the outer peripheral surface of the axial portion 71 over the entire circumference at the center portion in the long side direction (axial direction) of the axial portion 71. According to the above structure, each crankshaft 7A, 7B, 7C rotates (rotates) around the axis Ax2 through the axial portion 71, so that the eccentric portion 72 performs eccentric motion.

[0087] In this basic structure, the axial portion 71 and the two eccentric portions 72 are integrally formed by one metal member, thereby realizing a seamless crankshaft 7A, 7B, 7C. The crankshaft 7A, 7B, 7C of this shape is combined with the eccentric body bearing 5 to the planetary gear 3. Therefore, in a state where the eccentric body bearing 5 and the crankshaft 7A, 7B, 7C are combined with the planetary gear 3, when the crankshaft 7A, 7B, 7C rotates, the planetary gear 3 swings around the rotation axis Ax1.

[0088] The eccentric bearing 5 has a plurality of rotating bodies 51 (see Figure 4 ), is a part for absorbing the self-rotation component of the rotation of the crankshafts 7A, 7B, 7C and transmitting only the rotation of the crankshafts 7A, 7B, 7C other than the self-rotation component of the crankshafts 7A, 7B, 7C, that is, the swing component (revolution component) of the crankshafts 7A, 7B, 7C to the planetary gear 3. A plurality of rotating bodies 51 are arranged between the outer peripheral surface of the eccentric portion 72 of each crankshaft 7A, 7B, 7C and the inner peripheral surface of each opening portion 33 of the planetary gear 3. That is, the eccentric portion 72 of each crankshaft 7A, 7B, 7C functions as the inner ring of the eccentric body bearing 5, and the inner peripheral surface of each opening portion 33 of the planetary gear 3 functions as the outer ring of the eccentric body bearing 5.

[0089] In a state where the eccentric bearing 5 and the plurality of crankshafts 7A, 7B, 7C are combined with the planetary gear 3, when each crankshaft 7A, 7B, 7C rotates, the eccentric bearing 5 rotates around the axis Ax2 (eccentric motion). At this time, the rotation component of the crankshafts 7A, 7B, 7C is absorbed by the eccentric bearing 5. Therefore, only the rotation of the crankshafts 7A, 7B, 7C other than the rotation component of the crankshafts 7A, 7B, 7C, that is, the swing component (revolution component) of the crankshafts 7A, 7B, 7C is transmitted to the planetary gear 3 through the eccentric bearing 5. Therefore, in a state where the eccentric bearing 5 and the crankshafts 7A, 7B, 7C are combined with the planetary gear 3, when the crankshafts 7A, 7B, 7C rotate, the planetary gear 3 swings around the rotation axis Ax1.

[0090] In the gear device 1 of the above structure, a rotational force as an input is applied to the input shaft 500, and the input shaft 500 rotates around the rotation axis Ax1, thereby causing the planetary gear 3 to swing (revolve) around the rotation axis Ax1. At this time, the planetary gear 3 swings in a state where the inner side of the internal gear 2 is inscribed relative to the internal gear 2 and a part of the external teeth 31 is meshed with a part of the internal teeth 21, so that the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2. As a result, a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated between the two gears (the internal gear 2 and the planetary gear 3). In addition, the rotation (autorotation component) of the planetary gear 3 other than the swing component (revolution component) of the planetary gear 3 is transmitted to the pair of gear carriers 18 and 19 through the plurality of crankshafts 7A, 7B, and 7C. As a result, a rotation output that is reduced in speed at a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears is obtained from the pair of gear carriers 18 and 19.

[0091] In addition, in the gear device 1 of this basic structure, 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 relative to the input rotation in the gear device 1. That is, when the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2", the reduction ratio R1 is expressed by the following formula 1.

[0092] R1=V2 / (V1-V2) (Formula 1)

[0093] In short, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3 is, the larger the reduction ratio R1 is. 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 according to the above formula 1, the reduction ratio R1 is "35". At this time, when viewed from the input side of the rotating axis Ax1, each crankshaft 7A, 7B, 7C is centered on the axis Ax2 of the axis portion 71 (refer to Figure 5 and Figure 6 ) rotates one circle (360 degrees) in the clockwise direction around the rotation axis Ax1, the pair of gear carriers 18 and 19 rotates counterclockwise around the rotation axis Ax1 by an amount corresponding to the tooth number difference "2" (i.e., approximately 10.3 degrees).

[0094] According to the gear device 1 of this basic structure, such a high reduction ratio R1 can be realized by the combination of the internal gear 2 and the planetary gear 3. Furthermore, between the input gear 501 and the plurality of crankshaft gears 502A, 502B, 502C, an appropriate reduction ratio can be realized according to the number of teeth of the input gear 501 and the crankshaft gears 502A, 502B, 502C. As a result, the gear device 1 as a whole can realize a high reduction ratio.

[0095] The gear device 1 only needs to include at least the internal gear 2, the planetary gear 3, the crankshafts 7A, 7B, 7C, and a pair of gear carriers 18, 19. Figure 4 As shown, the spacer 11 is further provided. The spacer 11 is arranged between the pair of planetary gears 3 (the first planetary gear 301 and the second planetary gear 302) in a direction (axial direction) parallel to the rotation axis Ax1.

[0096] (Reference Example 1)

[0097] The internal meshing planetary gear device 1A of this reference example (hereinafter also referred to as "gear device 1A") is as follows Figure 7 to Figure 14 As shown, the structure around the crankshafts 7A, 7B, and 7C is different from the basic gear device 1. Hereinafter, the same reference numerals are given to the same structures as the basic structure, and the description thereof is appropriately omitted. Figure 7 It is a schematic cross-sectional view of the gear device 1A. Figure 8 This is a schematic diagram of the gear device 1A as viewed from the output side of the rotation axis Ax1. Fig. 9 It is a schematic perspective view of peripheral components of one crankshaft 7A. Fig.10 It is a schematic exploded perspective view of peripheral components of one crankshaft 7A. Fig.11 It is a schematic perspective view of one crankshaft 7A. Fig.12 yes Figure 7 A magnified view of area Z1. Fig.13 yes Figure 7 A magnified view of area Z2. Fig.14 yes Fig.13 A magnified view of area Z1.

[0098] The gear device 1A of this reference example is as follows Figure 7 As shown, it is also provided with a plurality of oil seals 121, 122, etc. The oil seal 121 blocks the gap between the housing 10 and the outer peripheral surface of the output side gear frame 19. The oil seal 122 blocks the central hole 193 formed in the central portion of the output side gear frame 19. The space enclosed by these multiple oil seals 121, 122, etc. constitutes a lubricant retaining space 17. The lubricant retaining space 17 includes the space between the inner wheel 61 and the outer wheel 62 of the bearing member 6. Furthermore, in the lubricant retaining space 17, a plurality of outer pins 23, planetary gears 3, a pair of roller bearings 41, 42 and an eccentric body bearing 5, etc. are accommodated.

[0099] Furthermore, a lubricant is injected into the lubricant retaining space 17. The lubricant is a liquid and can flow in the lubricant retaining space 17. Therefore, when the gear device 1 is used, the lubricant enters the meshing portion between, for example, the inner teeth 21 including a plurality of outer pins 23 and the outer teeth 31 of the planetary gear 3. The "liquid" referred to in the present disclosure includes liquid or gel-like substances. The "gel-like" referred to here refers to a state having intermediate properties between a liquid and a solid, including a colloid state including two phases, a liquid phase and a solid phase. For example, an emulsion (emulsion) in which the dispersant is a liquid phase and the dispersion is a liquid phase, a suspension (suspension) in which the dispersion is a solid phase, and the like are called gel (gel) or sol (sol) and are included in the "gel-like". Moreover, a state in which the dispersant is a solid phase and the dispersion is a liquid phase is also included in the "gel-like". In this basic structure, as an example, the lubricant is a liquid lubricating oil (oil).

[0100] The gear device 1A of this reference example further includes a pair of covers 13 and 14 mounted on both axial sides of a pair of gear carriers 18 and 19. When the pair of covers 13 and 14 are separated from each other, the input side ( Figure 7 The cover 13 located on the output side (right side in the figure) of the rotation axis Ax1 is referred to as the "input side cover 13". Figure 7 The cover 14 (left side in the figure) is called "output side cover 14". In this reference example, the material of the pair of covers 13 and 14 is a metal such as stainless steel, cast iron, carbon steel for mechanical structure or chrome-molybdenum steel, or a metal subjected to heat treatment.

[0101] The input side cover 13 is formed into a disk shape with the rotation axis Ax1 as the center. Here, at least the outer peripheral surface of the input side cover 13 is a perfect circle with the rotation axis Ax1 as the center when viewed from above (when viewed from one side in the axial direction). The outer diameter of the input side cover 13 is one circle smaller than the outer diameter of the input side gear frame 18. The input side cover 13 is viewed from the outside, that is, from the side opposite to the planetary gear 3 when viewed from the input side gear frame 18 ( Figure 7 The right side in the middle) is installed to the input side gear frame 18.

[0102] The output side cover 14 is formed into a disk shape with the rotation axis Ax1 as the center. Here, at least the outer peripheral surface of the output side cover 14 is a perfect circle with the rotation axis Ax1 as the center when viewed from above (when viewed from one side in the axial direction). The outer diameter of the output side cover 14 is one circle smaller than the outer diameter of the output side gear frame 19. The output side cover 14 is viewed from the outside, that is, from the side opposite to the planetary gear 3 when viewed from the output side gear frame 19 ( Figure 7 The left side is installed on the output side gear frame 19.

[0103] Here, the pair of covers 13 and 14 are detachably mounted on the pair of gear racks 18 and 19. That is, the input side cover 13 is detachably mounted on the input side gear rack 18, and the output side cover 14 is detachably mounted on the output side gear rack 19. In this reference example, as an example, each cover 13 and 14 is fixed by a plurality of fixing bolts 142 (see Figure 8 ) is mounted on each gear frame 18, 19. Therefore, by removing the plurality of fixing bolts 142, each cover 13, 14 can be removed from each gear frame 18, 19.

[0104] Here, in the output side cover 14 of the pair of covers 13 and 14, as shown in FIG. Figure 8 As shown, the plurality of mounting holes 194 (see Figure 7 ) are provided in a plurality of through holes 141 in a consistent manner. That is, a plurality of mounting holes 194 (female threads) for fixing the target component are provided in the output side gear rack 19. Therefore, in the output side cover 14 installed on the outside of the output side gear rack 19, a plurality of through holes 141 are also formed at positions corresponding to these plurality of mounting holes 194. In particular, in the case where a high torque is transmitted from the output side gear rack 19 to the target component, the number of mounting holes 194 and through holes 141 increases. Moreover, the configuration and number of mounting holes 194 and through holes 141 must be consistent with the target component.

[0105] On the other hand, the shaft holes 131 (see Figure 7 ) is provided only on the input side cover 13 of the pair of covers 13 and 14. That is, in the input side cover 13, a plurality of shaft holes 131 are provided corresponding to the plurality of crankshafts 7A, 7B, 7C. The shaft center portion 71 of each crankshaft 7A, 7B, 7C is inserted into each shaft hole 131. Here, the inner diameter of each shaft hole 131 is set to be one circle larger than the outer diameter of the shaft center portion 71 so as to prevent the shaft center portion 71 from contacting the inner peripheral surface of the shaft hole 131.

[0106] In addition, as for the peripheral structure of each crankshaft 7A, 7B, 7C, if it is described in more detail, the gear device 1A of this reference example adopts Figures 9 to 11 Here, the crankshaft 7A is described as an example, but the same structure is adopted for the crankshafts 7B and 7C.

[0107] That is, the crankshaft 7A has a flange portion 73 between two eccentric portions 72 in the axial direction along the axis Ax2. The flange portion 73 is in the shape of a disk centered on the axis Ax2, and at least the outer peripheral surface is a perfect circle when viewed from above. The outer diameter of the flange portion 73 is set to be one circle larger than the outer diameter of the eccentric portion 72, and the flange portion 73 is in the shape of a flange protruding from the outer peripheral surface of the eccentric portion 72 over the entire circumference. In this reference example, as an example, the axis portion 71, the two eccentric portions 72 and the flange portion 73 are seamlessly integrated.

[0108] Here, the crankshaft 7A has two eccentric portions 72 relative to one axial portion 71, and therefore has step portions 70 at at least two locations in the axial direction. That is, the diameter of the crankshaft 7A is not uniform over the entire length, and the diameter changes at least between the axial portion 71 and each eccentric portion 72, so two step portions 70 are generated in this portion. In other words, the end surface of each eccentric portion 72 facing the axial outer side (i.e., the opposite side to the flange portion 73) is a step portion 70.

[0109] In this reference example, the diameter of the two ends of the shaft center portion 71 of the crankshaft 7A in the axial direction is smaller than that in the central portion in the axial direction. Therefore, the stepped portions 70 are also generated at the locations where the diameter of the shaft center portion 71 changes. As a result, the crankshaft 7A has stepped portions 70 at four locations in the axial direction. Here, when distinguishing the stepped portions 70, from the input side ( Figure 7 The first step portion 701, the second step portion 702, the third step portion 703, and the fourth step portion 704 are provided in order from the right side (in the middle). That is, the first step portion 701 and the second step portion 702 are end surfaces facing the input side of the rotation axis Ax1, and the third step portion 703 and the fourth step portion 704 are end surfaces facing the output side of the rotation axis Ax1. The end portion of the shaft core portion 71 that is closer to the input side of the rotation axis Ax1 than the first step portion 701 constitutes a mounting portion 74 for mounting the crankshaft gear 502A.

[0110] A pair of roller bearings 41, 42, a pair of eccentric bearings 5, washers 81 to 85, and a retaining ring 86 are assembled to this crankshaft 7A. That is, the eccentric bearings 5 ​​are respectively mounted on the two eccentric portions 72 of the crankshaft 7A. Furthermore, a pair of roller bearings 41, 42 are mounted on the axial center portion 71 of the crankshaft 7A at positions on both sides of the two eccentric portions 72 in the axial direction. Furthermore, on the output side ( Figure 7 A groove 75 for inserting the retaining ring 86 is formed at the end portion (the left side in the figure) of the shaft core portion 71. Therefore, the retaining ring 86 is mounted at the end portion on the output side of the rotation axis Ax1 in the shaft core portion 71.

[0111] Here, on the input side ( Figure 7 The washer 81, the eccentric bearing 5, the washer 82, and the roller bearing 41 are installed in order from the flange portion 73 side. On the other hand, on the output side ( Figure 7The washer 83, the eccentric body bearing 5, the washer 84, the roller bearing 42, the washer 85, and the retaining ring 86 are installed in order from the flange portion 73 side. Therefore, on the input side of the rotation axis Ax1 as viewed from the flange portion 73, the washer 81 is interposed between the flange portion 73 and the eccentric body bearing 5, and the washer 82 is interposed between the eccentric body bearing 5 and the roller bearing 41. On the output side of the rotation axis Ax1 as viewed from the flange portion 73, the washer 83 is interposed between the flange portion 73 and the eccentric body bearing 5, and the washer 84 is interposed between the eccentric body bearing 5 and the roller bearing 42. Furthermore, the roller bearing 42 contacts the retaining ring 86 via the washer 85, thereby restricting the movement toward the output side of the rotation axis Ax1.

[0112] In more detail, the eccentric portion 72 is inserted into washers 81 and 83, respectively, and the axial portion 71 is inserted into washers 82 and 84, respectively. Here, the washer 82 is interposed between the second step portion 702 of the crankshaft 7A and the roller bearing 41. On the other hand, the washer 84 is interposed between the third step portion 703 of the crankshaft 7A and the roller bearing 42. Furthermore, the washer 85 is interposed between the fourth step portion 704 of the crankshaft 7A and the retaining ring 86. These washers 81 to 85 are made of metal, for example, and function as a track wheel (track disk) that reduces friction between the two components.

[0113] In addition, the gear device 1A of this reference example is as follows Fig.12 As shown, there is a limiting structure 9 for limiting the axial movement of each crankshaft 7A, 7B, 7C. That is, in the gear device 1A of this reference example, the limiting structure 9 limits the axial movement of the crankshafts 7A, 7B, 7C. The "axial direction" mentioned in this disclosure refers to the direction along the axis Ax2 of the crankshaft 7A, 7B, 7C, especially the direction parallel to the axis Ax2 of the crankshaft 7A, 7B, 7C (thrust direction). Moreover, the "limited movement" mentioned in this disclosure refers to the implementation of certain restrictions on movement, which includes not only completely prohibiting movement, but also limiting the range of movement or making it difficult to move. That is, in this reference example, a limiting structure 9 is provided, thereby limiting the movement of the crankshafts 7A, 7B, 7C in the axial direction along the axis Ax2 of the crankshafts 7A, 7B, 7C.

[0114] In this reference example, as an example, the restriction structure 9 prohibits the movement of the crankshafts 7A, 7B, and 7C on one side (the input side of the rotation axis Ax1) and the other side (the output side of the rotation axis Ax1) in the axial direction. Figure 8 In the example, the limiting structure prohibits the movement of the crankshafts 7A, 7B, 7C toward the right in the figure and toward the left in the figure relative to the pair of gear carriers 18 and 19. As a result, the positions of the crankshafts 7A, 7B, 7C in the axial direction (relative to the pair of gear carriers 18 and 19) are positioned to a fixed position.

[0115] Specifically, in this reference example, the limiting structure 9 includes a pair of covers 13 and 14 installed on both axial sides of a pair of gear carriers 18 and 19. In short, the gear device 1A uses the input side cover 13 and the output side cover 14 to limit the axial movement of each crankshaft 7A, 7B, 7C. In particular, the gear device 1A of this reference example has a limiter 13 that limits the axial movement of the crankshaft 7A, 7B, 7C to one side ( Figure 8 The first limiting structure 91 that limits the movement of the crankshafts 7A, 7B, 7C toward the other axial side ( Figure 8 The second limiting structure 92 that moves (left in the middle) serves as the limiting structure 9.

[0116] Here, the input side cover 13 is included in the first limiting structure 91, and receives the input side cover 13 from the crankshaft 7A, 7B, 7C toward one side in the axial direction ( Figure 8 On the other hand, the output side cover 14 is included in the second limiting structure 92, and by receiving the force F1 from the crankshaft 7A, 7B, 7C to the other axial side ( Figure 8 The force F2 acting on the crankshafts 7A, 7B, and 7C toward the other axial side is limited.

[0117] More specifically, the first limiting structure 91 includes the input side cover 13 and the first step portion 701 of the crankshafts 7A, 7B, 7C. According to the first limiting structure 91, the input side ( Figure 8 The first step portion 701 (right side in the figure) contacts the output side (outlet side) of the input side cover 13 toward the rotation axis Ax1. Figure 8 The crankshafts 7A, 7B, and 7C are axially oriented to one side ( Figure 8 That is, the first step difference portion 701 of the crankshafts 7A, 7B, 7C contacts the input side cover 13 mounted on the input side gear frame 18, thereby prohibiting the movement of the crankshafts 7A, 7B, 7C toward one side in the axial direction.

[0118] The second limiting structure 92 includes the output side cover 14 and the end surface 76 on the output side of the rotation axis Ax1 of the crankshaft 7A, 7B, 7C. According to this second limiting structure 92, the output side ( Figure 8 The end surface 76 of the output side cover 14 (left side) contacts the input side ( Figure 8 The crankshafts 7A, 7B, and 7C are oriented toward the other axial side ( Figure 8That is, the end faces 76 of the crankshafts 7A, 7B, 7C contact the output side cover 14 mounted on the output side gear frame 19, thereby prohibiting the movement of the crankshafts 7A, 7B, 7C toward the other axial side.

[0119] Here, in the limiting structure 9, the part of the crankshaft 7A, 7B, 7C other than the end face of the eccentric portion 72 (the second step portion 702 and the third step portion 703) contacts the pair of covers 13 and 14. That is, the limiting structure 9 is located axially further outward than the step portions 702 and 703 of the end face of the eccentric portion 72 of the crankshaft 7A, 7B, 7C, and limits the axial movement of the crankshaft 7A, 7B, 7C by contacting the end face (the first step portion 701 or the end face 76) facing the axial outside. Therefore, in the step portions 702 and 703 of the end face of the eccentric portion 72, friction will not be generated due to contact with the pair of covers 13 and 14, etc., and wear of the step portions 702 and 703 can be reduced.

[0120] In addition, the gear device 1A of this reference example includes an internal gear 2, planetary gears 3, crankshafts 7A, 7B, 7C and a pair of gear carriers 18, 19, and the planetary gears 3 are swung to rotate relative to the internal gear 2. The internal gear 2 has: an annular gear body 22; and a plurality of outer pins 23, which are held in a plurality of inner circumferential grooves 223 formed on the inner circumferential surface 221 of the gear body 22 in a rotatable state and constitute the internal teeth 21. The planetary gear 3 has outer teeth 31 that partially mesh with the internal teeth 21. The crankshafts 7A, 7B, 7C have step portions 70 at at least two locations along the axial direction of the axis Ax2, and the planetary gears 3 are swung by rotating around the axis Ax2. A pair of gear carriers 18, 19 are arranged on both sides of the axial direction of the planetary gear 3, and rotatably support the crankshafts 7A, 7B, 7C. Here, as Fig.13 As shown, lubrication passages S1 for passing lubricant are formed between the step portion 70 and the pair of carriers 18 and 19 .

[0121] That is, in this reference example, a lubrication passage S1 is ensured between the step portion 70 and the pair of gear carriers 18, 19. By ensuring such a lubrication passage S1, in the gear device 1A, the lubricant can be circulated through the lubrication passage S1, thereby improving the lubrication state of the pair of roller bearings 41, 42 and the pair of eccentric body bearings 5, etc. Fig.13 In FIG. 1 , the flow (circulation) of the lubricant in the lubrication passage S1 is conceptually shown by the dotted arrows.

[0122] In this reference example, the lubricant passage S1 is formed in the lubricant holding space 17 into which the lubricant is injected. By forming such a lubricant passage S1, it is difficult to produce "lubricant shortage" in which the lubricant is insufficient or exhausted around the crankshafts 7A, 7B, and 7C, and a certain amount of lubricant or more is always supplied. In addition, compared with a structure in which the lubricant stagnates at a fixed position, the lubricant circulates through the lubricant passage S1, thereby rotating the lubricant around the crankshafts 7A, 7B, and 7C at any time, thereby suppressing the deterioration of the lubricant.

[0123] Therefore, the lubrication state of the pair of roller bearings 41, 42 and the pair of eccentric bearings 5 ​​is improved, and poor lubrication is unlikely to occur. Therefore, even when the gear device 1A is used for a long time, the loss caused by friction can be reduced, and the life of the gear device 1A can be easily extended. In short, the gear device 1A of this reference example is unlikely to have a decrease in reliability, especially when used for a long time, and thus it also contributes to the improvement of the transmission efficiency, the extension of the life, and the high performance of the gear device 1A.

[0124] Here, in this reference example, the lubrication passage S1 includes a radial passage S11 for passing the lubricant in a radial direction orthogonal to the axial direction. Fig.13 A schematic enlarged view of area Z1 Fig.14 As shown, the lubrication passage S1 formed between the step portion 70 and the pair of gear carriers 18 and 19 includes at least a radial passage S11 for passing the lubricant in the radial direction. Thus, when the crankshafts 7A, 7B, and 7C rotate, the lubricant passes in the radial direction by centrifugal force, so that the lubricant can be efficiently circulated through the lubrication passage S1.

[0125] Moreover, in this reference example, in the axial direction, there is a gap between the step portions 702, 703 and at least one of the pair of gear carriers 18, 19, and the lubrication passage S1 includes the gap. In this reference example, as described above, the step portions 702, 703 including at least the end surface of the eccentric portion 72 are not used as the limiting structure 9, so a gap can be provided between the step portions 702, 703 and the pair of gear carriers 18, 19, and the gap is used as a part of the lubrication passage S1. In this reference example, as an example, the gaps generated between the step portions 702, 703 and the pair of gear carriers 18, 19 constitute a part of the lubrication passage S1.

[0126] Furthermore, in this reference example, a plate-like component (washer 82, 84) is further provided between the step portion 70 and the pair of gear carriers 18, 19. The lubrication passage S1 includes a groove 80 (see FIG. 1 ) formed on the surface of the plate-like component (washer 82, 84) facing the gear carriers 18, 19. Fig.10 ). That is, Fig.10As shown, in washers 81 to 84, grooves 80 extending in the radial direction are formed on the surface facing the axial outside (the gear carrier 18, 19 side). Here, it is preferred to form a plurality of grooves 80 for each washer 81 to 84. In this reference example, as an example, four grooves 80 are formed for each washer 81 to 84. The four grooves 80 are arranged at equal intervals in the circumferential direction of each washer 81 to 84. By providing such grooves 80, the lubricant flows through the grooves 80, and the grooves 80 are contained in the lubrication passage S1. As a result, compared with the case where there is no groove 80, the cross-sectional area of ​​the lubrication passage S1 can be enlarged, and the lubricant becomes easier to circulate.

[0127] Furthermore, when a plurality of crankshafts 7A, 7B, and 7C are provided as in the present reference example, it is preferable to provide a connecting passage S2 that connects a plurality of lubrication passages S1 formed around the plurality of crankshafts 7A, 7B, and 7C. Thus, the lubricant can be circulated between the plurality of crankshafts 7A, 7B, and 7C, and the lubricant can be circulated in the entire gear device 1A, so that further improvement in the lubrication state can be expected.

[0128] Specifically, if Figure 7 As shown in FIG. 1 , each of the pair of covers 13 and 14 has grooves 133 and 143 formed on the surface facing the axial inner side (the surface on the planetary gear 3 side). The grooves 133 and 143 are annular grooves centered on the rotation axis Ax1 and formed so that roller bearings 41 and 42 supporting the plurality of crankshafts 7A, 7B, and 7C pass through them when viewed from above (see FIG. 1 ). Figure 8 ). Therefore, the lubrication passage S1 including the plurality of (here, three) roller bearings 41 is connected by the connection passage S2 including the groove 133 of the input side cover 13. Similarly, the lubrication passage S1 including the plurality of (here, three) roller bearings 42 is connected by the connection passage S2 including the groove 143 of the output side cover 14.

[0129] The gear device 1A of the reference example includes an input gear 501 that rotates around a rotation axis Ax1 and a plurality of crank gears 502A, 502B, and 502C. The plurality of crank gears 502A, 502B, and 502C are arranged around the input gear 501 in a manner that meshes with the input gear 501, and rotate synchronously with each other when the input gear 501 rotates. A plurality of crankshafts 7A, 7B, and 7C are provided in a one-to-one correspondence with the plurality of crank gears 502A, 502B, and 502C. The plurality of crankshafts 7A, 7B, and 7C rotate together with the plurality of crank gears 502A, 502B, and 502C, and the planetary gear 3 swings around the rotation axis Ax1.

[0130] Thus, in the split type gear device 1A having the plurality of crankshafts 7A, 7B, 7C, the axial movement of the plurality of crankshafts 7A, 7B, 7C can be restricted. Furthermore, by circulating the lubricant around the plurality of crankshafts 7A, 7B, 7C, the lubrication state can be improved.

[0131] The gear device 1A of this reference example is as follows Fig.15 As shown, the robot joint device 200 is constituted together with the first member 201 and the second member 202. In other words, the robot joint device 200 of this reference example includes the gear device 1A, 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 as the planetary gear 3 rotates relative to the internal gear 2. Fig.15 2 is a schematic cross-sectional view of the robot joint device 200. Fig.15 , a first member 201, a second member 202, and a driving source 101 are schematically shown.

[0132] The robot joint device 200 constructed in this way functions as a joint device by the first member 201 and the second member 202 rotating relative to each other around the rotation axis Ax1. Here, the first member 201 and the second member 202 rotate relative to each other by driving the input shaft 500 of the gear device 1A using the drive source 101. At this time, the rotation (input rotation) generated by the drive source 101 is decelerated at a relatively high reduction ratio in the gear device 1A, thereby driving the first member 201 or the second member 202 with a relatively high torque. That is, the first member 201 and the second member 202 connected by the gear device 1A can perform flexion and extension movements around the rotation axis Ax1.

[0133] The robot joint device 200 is used, for example, in a robot such as a horizontal multi-joint robot (SCARA type robot). Furthermore, the robot joint device 200 is not limited to a horizontal multi-joint robot, and may be used, for example, in an industrial robot other than a horizontal multi-joint robot or a robot other than an industrial robot. Furthermore, the gear device 1A of this reference example is not limited to the robot joint device 200, and may be used, for example, as a wheel device such as an in-wheel motor and in a vehicle such as an Automated Guided Vehicle (AGV).

[0134] <Modification>

[0135] Reference Example 1 is only one of the various reference examples disclosed in the present invention. As long as the purpose of the present invention can be achieved, various changes can be made to Reference Example 1 according to the design, etc. Moreover, the drawings referred to in the present invention are all schematic drawings, and the size and thickness ratios of the components in the drawings do not necessarily reflect the actual size ratios. The following lists the modified examples of Reference Example 1. The modified examples described below can be appropriately combined and applied.

[0136] The number of crankshafts 7A, 7B, and 7C is not limited to "3", and may be 2 or 4 or more. Furthermore, if there is only one crankshaft, an eccentric swing type internal meshing planetary gear device can be realized in which the rotation axis Ax1 coincides with the axis Ax2 of the crankshaft, rather than a separation type. At this time, by driving the crankshaft, the planetary gear 3 swings, so that a pair of gear carriers 18 and 19 can rotate relative to the gear body 22 around the rotation axis Ax1.

[0137] In addition, in reference example 1, a gear device 1A of the type having two planetary gears 3 is illustrated, but the gear device 1A may also include three or more planetary gears 3. For example, when the gear device 1A includes three planetary gears 3, it is preferred that the three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. In addition, the gear device 1A may also include only one planetary gear 3. Alternatively, when the gear device 1A includes three planetary gears 3, two of the three planetary gears 3 may be in the same phase, and the remaining one planetary gear 3 may be arranged with a phase difference of 180 degrees around the rotation axis Ax1.

[0138] Furthermore, the bearing member 6 may be a cross roller bearing, a deep groove ball bearing, a four-point contact ball bearing, or the like.

[0139] The number of teeth of the input gear 501, the number of teeth of the crank gears 502A, 502B, 502C, the number of outer pins 23 (the number of teeth of the internal teeth 21), and the number of teeth of the external teeth 31 described in Reference Example 1 are merely examples and may be changed as appropriate.

[0140] Furthermore, the eccentric bearing 5 is not limited to a roller bearing, and may be, for example, a deep groove ball bearing or an angular contact ball bearing.

[0141] Furthermore, the material of each component of the gear device 1A is not limited to metal, and may be, for example, resin such as engineering plastic.

[0142] Furthermore, the gear device 1A is not limited to a structure in which the rotational force of the inner wheel 61 (input side gear frame 18 and output side gear frame 19) is derived as output, as long as the relative rotation between the inner wheel 61 and the outer wheel 62 of the bearing member 6 can be derived as output. For example, the rotational force of the outer wheel 62 (housing 10) rotating relative to the inner wheel 61 can also be derived as output.

[0143] Moreover, in reference example 1, the end face 76 on the output side of the rotation axis Ax1 of the crankshaft 7A, 7B, 7C directly contacts the output side cover 14, but the structure is not limited to this, and a plate-like component such as a gasket member may be arranged between the end face 76 and the output side cover 14. In this case, when the output side cover 14 is installed, by adjusting the thickness (and / or the number of pieces) of the plate-like component, the gap between the end face 76 and the output side cover 14 can be adjusted in the axial direction, thereby adjusting the axial "play" of the crankshaft 7A, 7B, 7C. Furthermore, the plate-like component functions as a track wheel (track disk) that reduces the friction between the end face 76 and the output side cover 14.

[0144] Furthermore, the lubricant is not limited to liquid substances such as lubricating oil (oil), and may be a gel-like substance such as grease.

[0145] (Implementation Method 1)

[0146] like Fig.16 and Fig.17 As shown, the internal meshing planetary gear device 1B of this embodiment (hereinafter also referred to as "gear device 1B") is different from the gear device 1A of reference example 1 in that the output side cover 14 (refer to Figure 7 ) Hereinafter, the same reference numerals are used for the same structures as those in Reference Example 1, and the description thereof will be appropriately omitted. Fig.16 It is a schematic cross-sectional view of the gear device 1B. Fig.17 Yes Fig.16 An enlarged schematic diagram of area Z1 is shown in the pop-up box, and a local enlarged diagram is shown in the pop-up box.

[0147] In the gear device 1B of this embodiment, the output side gear frame 19, the washer 84 and the third step portion 703 are used instead of the output side cover 14 to restrict the movement of each crankshaft 7A, 7B, 7C toward the other axial side. Moreover, the movement of each crankshaft 7A, 7B, 7C toward one axial side is restricted by the input side cover 13 and the step portion (the first step portion 701) as in the reference example 1.

[0148] That is, the gear device 1B includes an internal gear 2, planetary gears 3, crankshafts 7A, 7B, 7C, an input side gear frame 18, and an output side gear frame 19, and the planetary gears 3 are rotated relative to the internal gear 2 by swinging the planetary gears 3. The internal gear 2 includes: an annular gear body 22; and a plurality of outer pins 23, which are held in a plurality of inner peripheral grooves 223 formed on the inner peripheral surface 221 of the gear body 22 in a rotatable state and constitute the internal teeth 21. The planetary gears 3 include outer teeth 31 partially meshed with the internal teeth 21. The crankshafts 7A, 7B, 7C have step portions 70 at at least two locations along the axial direction of the axis Ax2, and the planetary gears 3 are swung by rotating around the axis Ax2. The input side gear frame 18 and the output side gear frame 19 are arranged on both sides of the axial direction of the planetary gears 3, and rotatably support the crankshafts 7A, 7B, 7C. Here, the gear device 1B is as follows: Fig.17 As shown, the first limiting structure 91 and the second limiting structure 92 are also provided. The first limiting structure 91 includes an input side cover 13 installed on the axial side of the input side gear frame 18 on the opposite side of the planetary gear 3, and the step difference portion 70 (the first step difference portion 701) is directly or indirectly contacted with the input side cover 13, thereby limiting the crankshafts 7A, 7B, 7C from moving toward one side ( Fig.17 The second limiting structure 92 limits the movement of the crankshafts 7A, 7B, 7C toward the other axial side (right) by making the step difference portion 70 (third step difference portion 703) directly or indirectly contact the output side gear frame 19. Fig.17 The movement of the left side).

[0149] Thus, in the present embodiment, the crankshafts 7A, 7B, 7C have the step portion 70, and the first limiting structure 91 includes the input side cover 13, and the step portion 70 is directly or indirectly in contact with the input side cover 13, thereby limiting the movement of the crankshafts 7A, 7B, 7C toward one side in the axial direction. In addition, the second limiting structure 92 limits the movement of the crankshafts 7A, 7B, 7C toward the other side in the axial direction by making the step portion 70 directly or indirectly in contact with the output side gear frame 19. That is, in the gear device 1B, the axial movement (movement toward the other side in the axial direction) of the crankshafts 7A, 7B, 7C can be limited by using the output side gear frame 19 instead of the output side cover 14. As a result, in the gear device 1B, there is no need to use a tapered roller bearing or the output cover 14 mounted on the output side gear frame 19, and although it is a relatively simple structure, it can limit the axial movement of the crankshafts 7A, 7B, 7C. Therefore, according to the structure of this embodiment, it is possible to reduce backlash and transmission loss caused by the axial movement of the crankshafts 7A, 7B, and 7C.

[0150] Moreover, the gear device 1B of this embodiment has the following advantages compared to the gear device 1A of reference example 1. That is, the depth of the multiple mounting holes 194 provided in the output side gear frame 19 can be ensured to be deep in accordance with the thickness of the output side cover 14, and it is easy to improve the mounting strength of the target component relative to the output side gear frame 19. Furthermore, since the output side cover 14 provided with the multiple through holes 141 corresponding to the multiple mounting holes 194 is omitted, it is not necessary to adjust the configuration and number of the through holes 141 according to the target component. In addition, the fixing bolts 142 (refer to Figure 8 ), so the mounting hole 194 can be provided without interfering with the fixing bolt 142.

[0151] Specifically, in the present embodiment, the third step portion 703 including the end surface of the eccentric portion 72 in each crankshaft 7A, 7B, 7C is indirectly in contact with the output side gear frame 19 via the washer 84. In other words, the washer 84 is clamped on the input side ( Fig.17 Between the surface (right side in the middle) and the end surface of the eccentric portion 72 (third step difference portion 703).

[0152] Fig.17 Yes Fig.16 A magnified schematic diagram of area Z1. Fig.17 As shown, the first limiting structure 91 includes the input side cover 13 and the first step difference portion 701 of the crankshaft 7A, 7B, 7C, similar to the reference example 1. According to this first limiting structure 91, the first step difference portion 701 of the crankshaft 7A, 7B, 7C on the input side facing the rotation axis Ax1 contacts the periphery of the shaft hole 131 on the surface of the input side cover 13 facing the output side facing the rotation axis Ax1, thereby restricting the movement of the crankshaft 7A, 7B, 7C toward one side in the axial direction. That is, the first step difference portion 701 of the crankshaft 7A, 7B, 7C contacts the input side cover 13 mounted on the input side gear frame 18, thereby prohibiting the movement of the crankshaft 7A, 7B, 7C toward one side in the axial direction. In other words, the input side cover 13 mounted on the input side gear frame 18 is subjected to the load from the crankshaft 7A, 7B, 7C toward one side in the axial direction ( Fig.17 The force F1 acting on the crankshafts 7A, 7B, 7C in the middle (right) is used to prevent the crankshafts 7A, 7B, 7C from moving to one side in the axial direction.

[0153] In short, in the first limiting structure 91, the portion other than the end surface (second step portion 702) of the eccentric portion 72 of the crankshaft 7A, 7B, 7C contacts the input side cover 13. That is, the first limiting structure 91 makes the portion located axially outward ( Fig.17The step portion (first step portion 701) which is located at a position (right side in the figure) and faces the axial outer side directly or indirectly contacts the input side cover 13, thereby limiting the movement of the crankshafts 7A, 7B, 7C toward one side in the axial direction. Therefore, in the second step portion 702 of the end surface including the eccentric portion 72, friction will not be generated due to contact with the input side cover 13, and wear of the step portion 702 can be reduced. In this embodiment, the first step portion 701 is directly in contact with the input side cover 13, but it is not limited to this structure. The first step portion 701 can also indirectly contact the input side cover 13 via a washer or the like.

[0154] The second limiting structure 92 includes the output side gear frame 19, the washer 84 and the third step portion 703. According to this second limiting structure 92, the third step portion 703 on the output side of the crankshaft 7A, 7B, 7C facing the rotation axis Ax1 contacts (indirectly via the washer 84) the input side of the output side gear frame 19 facing the rotation axis Ax1. Fig.17 The crankshafts 7A, 7B, and 7C are oriented toward the other axial side ( Fig.17 That is, the output side gear frame 19 receives the movement from the third step difference portion 703 toward the other axial side ( Fig.17 The force F2 acting on the crankshafts 7A, 7B, 7C toward the other axial side is thereby prohibited.

[0155] That is, in this embodiment, the second limiting structure 92 makes the step difference portion 70 (third step difference portion 703) indirectly contact the output side gear frame 19 via the plate-shaped part (washer 84), thereby limiting the movement of the crankshafts 7A, 7B, 7C toward the other axial side. Therefore, the plate-shaped part (washer 84) functions as a track wheel (track disk) that reduces the friction between the output side gear frame 19 and the step difference portion 70.

[0156] Moreover, in the present embodiment, the input side cover 13 in the first limiting structure 91 is detachably mounted to the input side gear frame 18. That is, the input side cover 13 is a component independent of the input side gear frame 18, and is mounted to the input side gear frame 18 when the gear device 1B is assembled. Therefore, when the gear device 1B is assembled, after the crankshafts 7A, 7B, 7C are inserted from the input side gear frame 18 side, the input side cover 13 is mounted to the input side gear frame 18, thereby limiting the movement of the crankshafts 7A, 7B, 7C toward one side in the axial direction. Therefore, by adjusting the installation position of the input side cover 13 relative to the input side gear frame 18, the axial "play" of the crankshafts 7A, 7B, 7C can be adjusted.

[0157] Here, preferably Fig.17As shown in the pop-up box, a gasket member 132 is interposed between the input side gear frame 18 and the input side cover 13. The gasket member 132 is, for example, a thin plate member made of metal. That is, in the axial direction, the input side cover 13 contacts the input side gear frame 18 via the gasket member 132. Therefore, when installing the input side cover 13, by adjusting the thickness (and / or the number of gasket members 132), the gap between the first step difference portion 701 and the input side cover 13 can be adjusted in the axial direction, thereby adjusting the axial "play" of the crankshafts 7A, 7B, and 7C.

[0158] Furthermore, in the present embodiment, in the first limiting structure 91, the step portion 70 (first step portion 701) of the crankshafts 7A, 7B, 7C directly or indirectly contacts the input side cover 13 mounted on the input side gear frame 18, thereby limiting the movement of the crankshafts 7A, 7B, 7C toward one side in the axial direction. That is, the crankshafts 7A, 7B, 7C are limited in axial movement not by the input side gear frame 18 but by the input side cover 13. The input side cover 13 is detachably mounted on the input side gear frame 18 and is therefore independent of the input side gear frame 18. Therefore, it is possible to limit the movement of the crankshafts 7A, 7B, 7C toward one side in the axial direction, and to ensure a gap between the second step portion 702 and the input side gear frame 18 that is a part of the lubrication passage S1 through which the lubricant passes.

[0159] Therefore, in the present embodiment, similarly to reference example 1, a lubrication passage S1 for passing lubricant is formed between the step portion 70 (second step portion 702) and the input side gear frame 18. Therefore, the lubrication state of the pair of roller bearings 41 and the pair of eccentric bearings 5 ​​is improved, and poor lubrication is unlikely to occur. Therefore, even when the gear device 1B is used for a long time, the loss caused by friction can be reduced, and the life of the gear device 1B can be easily extended. In short, the gear device 1B of the present embodiment is unlikely to decrease in reliability, especially when used for a long time, and therefore even contributes to the improvement of the transmission efficiency, life extension and high performance of the gear device 1B. On the other hand, in the present embodiment, no gap is generated between the output side gear frame 19 and the third step portion 703 constituting the second limiting structure 92, and if a general gasket 84 is used, a lubrication passage will not be generated between the output side gear frame 19 and the third step portion 703. However, when the washer 84 provided with the groove portion 80 is used, the lubricant can flow through the groove portion 80 , and a lubrication passage can be formed between the output side carrier 19 and the third step portion 703 constituting the second restriction structure 92 .

[0160] In addition, the gear device 1B of this embodiment is provided with an input gear 501 that rotates around the rotation axis Ax1 and a plurality of crank gears 502A, 502B, and 502C, similarly to the reference example 1. The plurality of crank gears 502A, 502B, and 502C are arranged around the input gear 501 in a manner that meshes with the input gear 501, and rotate synchronously with each other when the input gear 501 rotates. A plurality of crankshafts 7A, 7B, and 7C are provided in a manner that corresponds one-to-one to the plurality of crank gears 502A, 502B, and 502C. The plurality of crankshafts 7A, 7B, and 7C rotate together with the plurality of crank gears 502A, 502B, and 502C, and the planetary gear 3 swings around the rotation axis Ax1.

[0161] Thus, in the split type gear device 1B having the plurality of crankshafts 7A, 7B, 7C, the axial movement of the plurality of crankshafts 7A, 7B, 7C can be restricted. Furthermore, by circulating the lubricant around the plurality of crankshafts 7A, 7B, 7C, the lubrication state can be improved.

[0162] The structure of Embodiment 1 can be adopted in combination with the various structures (including modified examples) described in Reference Example 1 as appropriate.

[0163] (Summarize)

[0164] As described above, the first form of the internal meshing planetary gear device (1, 1A, 1B) includes an internal gear (2), a planetary gear (3), a crankshaft (7A, 7B, 7C), an input side gear frame (18), and an output side gear frame (19), and the planetary gear (3) is caused to rotate relative to the internal gear (2) by swinging the planetary gear (3). The internal gear (2) includes: an annular gear body (22); and a plurality of outer pins (23) which are held in a plurality of inner peripheral grooves (223) formed 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) includes an outer tooth (31) partially meshed with the internal tooth (21). The crankshaft (7A, 7B, 7C) includes a step portion (70) at least two locations along the axial direction of the axis (Ax2), and the planetary gear (3) is caused to swing by rotating around the axis (Ax2). The input side gear frame (18) and the output side gear frame (19) are arranged on both sides of the axial direction of the planetary gear (3) and can rotatably support the crankshaft (7A, 7B, 7C). The internally meshing planetary gear device (1, 1A, 1B) also has a first limiting structure (91) and a second limiting structure (92). The first limiting structure (91) includes an input side cover (13) installed on the axial side of the input side gear frame (18) on the opposite side of the planetary gear (3). The first limiting structure (91) limits the movement of the crankshaft (7A, 7B, 7C) toward one side in the axial direction by making the step difference portion (70) directly or indirectly contact the input side cover (13). The second limiting structure (92) limits the movement of the crankshaft (7A, 7B, 7C) toward the other side in the axial direction by making the step difference portion (70) directly or indirectly contact the output side gear frame (19).

[0165] According to this form, the movement of the crankshaft (7A, 7B, 7C) toward one side in the axial direction is restricted by making the step difference portion (70) directly or indirectly contact the input side cover (13) installed on the input side gear frame (18). On the other hand, the movement of the crankshaft (7A, 7B, 7C) toward the other side in the axial direction is restricted by making the step difference portion (70) directly or indirectly contact the output side gear frame (19). As a result, in the internal meshing planetary gear device (1, 1A, 1B), there is no need to use tapered roller bearings, etc., and although it is a relatively simple structure, it can restrict the axial movement of the crankshaft (7A, 7B, 7C). Therefore, looseness and transmission loss caused by the axial movement of the crankshaft (7A, 7B, 7C) can be reduced.

[0166] The second embodiment of the internally meshing planetary gear device (1, 1A, 1B) is characterized in that in the first embodiment, a lubrication passage (S1) for passing a lubricant is formed between the step portion (70) and the input side gear carrier (18).

[0167] According to this aspect, the lubricant can be circulated by utilizing the gap between the step portion (70) and the input side gear carrier (18) in the axial direction.

[0168] The third form of the internally meshing planetary gear device (1, 1A, 1B) is that in the first or second form, the second limiting structure (92) limits the movement of the crankshaft toward the other axial side by making the step difference portion indirectly contact the output side gear frame (19) via a plate-like part (washer 84), and the input side cover (13) is removably mounted to the input side gear frame (18).

[0169] According to this aspect, the plate-shaped component (washer 84) functions as a track wheel (track disk) that reduces the friction between the output side gear frame (19) and the step portion (70).

[0170] A fourth form of an internally meshing planetary gear device (1, 1A, 1B) is a device according to any one of the first to third forms, wherein a spacer member (132) is interposed between an input side gear carrier (18) and an input side cover (13).

[0171] According to this form, by adjusting the thickness (and / or the number of gasket members (132), the gap between the step difference portion (70) and the input side cover (13) can be adjusted in the axial direction, thereby adjusting the axial "play" of the crankshaft (7A, 7B, 7C).

[0172] A fifth aspect of the internally meshing planetary gear device (1, 1A, 1B) is characterized in that, in any one of the first to fourth aspects, the input side cover (13) is detachably mounted to the input side gear carrier (18).

[0173] According to this form, when assembling the internally meshing planetary gear device (1, 1A, 1B), after inserting the crankshaft (7A, 7B, 7C) from the input side gear frame (18), the input side cover (13) is installed on the input side gear frame (18), thereby limiting the axial movement of the crankshaft (7A, 7B, 7C).

[0174] The sixth form of the internally meshing planetary gear device (1, 1A, 1B) is a device according to any one of the first to fifth forms, wherein the crankshaft (7A, 7B, 7C) has an eccentric portion (72) that is eccentric relative to the axis (Ax2). The first limiting structure (91) is located axially outward relative to the end surface (step difference portion 702, 703) of the eccentric portion (72) in the crankshaft (7A, 7B, 7C), and the step difference portion (701) toward the axial outside is directly or indirectly brought into contact with the input side cover (13), thereby limiting the movement of the crankshaft (7A, 7B, 7C) toward one side in the axial direction.

[0175] According to this form, the step portion (701) of the crankshaft (7A, 7B, 7C) which is not the end surface (step portion 702, 703) of the eccentric portion (72) is used to limit the axial movement of the crankshaft (7A, 7B, 7C), thereby reducing the wear of the eccentric portion (72).

[0176] The seventh embodiment of the internally meshing planetary gear device (1, 1A, 1B) is any one of the first to sixth embodiments, further comprising: an input gear (501) that rotates around a rotation axis (Ax1); and a plurality of crankshaft gears (502A, 502B, 502C) that are arranged around the input gear (501) in a manner that meshes with the input gear (501) and rotate synchronously with each other when the input gear (501) rotates. A plurality of crankshafts (7A, 7B, 7C) are provided in a manner that corresponds one-to-one with the plurality of crankshaft gears (502A, 502B, 502C). The plurality of crankshafts (7A, 7B, 7C) rotate together with the plurality of crankshaft gears (502A, 502B, 502C) to cause the planetary gear (3) to oscillate around the rotation axis (Ax1).

[0177] According to this aspect, in a split-type internally meshing planetary gear device (1, 1A, 1B), although the structure is relatively simple, the axial movement of the crankshaft (7A, 7B, 7C) can be restricted.

[0178] The eighth form of a robot joint device (200) comprises: an internally meshing planetary gear device (1, 1A, 1B) of any one of the first to seventh forms; a first component (201) fixed to a gear body (22); and a second component (202) rotating relative to the first component (201) as the planetary gear (3) rotates relative to the internal gear (2).

[0179] According to this aspect, although it is a relatively simple structure, the axial movement of the crankshaft (7A, 7B, 7C) can be restricted.

[0180] The structures of the second to seventh aspects are not essential structures of the internal meshing planetary gear device (1, 1A, 1B) and can be omitted as appropriate.

[0181] [Explanation of Symbols]

[0182] 1, 1A, 1B: Internal meshing planetary gear device

[0183] 2: Internal gear

[0184] 3: Planetary gear

[0185] 7A, 7B, 7C: Crankshaft

[0186] 13: Input side cover

[0187] 18: Input side gear rack

[0188] 19: Output side gear rack

[0189] 21: Internal teeth

[0190] 22: Gear body

[0191] 23: Export

[0192] 31: External teeth

[0193] 70, 701, 702, 703, 704: Step difference

[0194] 84: Washer (plate-shaped part)

[0195] 91: 1st Restriction Structure

[0196] 92: Second Restriction Structure

[0197] 132: Gasket component

[0198] 200: Joint device for robots

[0199] 201: Component 1

[0200] 202: Component 2

[0201] 221: Inner surface (of the gear body)

[0202] 223: Inner groove

[0203] 501: Input gear

[0204] 502A, 502B, 502C: Crankshaft gear

[0205] Ax1: Rotation axis

[0206] Ax2: Axis

[0207] S1: Lubrication passage

Claims

1. An internally meshing planetary gear device, comprising: An internal gear having an annular gear body and a plurality of outer pins, wherein the plurality of outer pins are held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a rotatable state and constitute internal teeth; a planetary gear having external teeth partially meshing with the internal teeth; a crankshaft having step portions at at least two locations along the axial direction of the axis, and causing the planetary gear to oscillate by rotating about the axis; and The input side gear carrier and the output side gear carrier are arranged on both sides of the axial direction of the planetary gear and rotatably support the crankshaft. By swinging the planetary gear, the planetary gear is rotated relative to the internal gear. The internal meshing planetary gear device also has: a first limiting structure, comprising an input side cover mounted on the input side gear carrier on the axial direction opposite to the planetary gear, and limiting movement of the crankshaft toward one side in the axial direction by making the step portion directly or indirectly contact the input side cover; and The second restriction structure restricts movement of the crankshaft toward the other axial side by causing the step portion to directly or indirectly contact the output-side carrier.

2. The internally meshing planetary gear device according to claim 1, wherein A lubrication passage through which lubricant passes is formed between the step portion and the input-side carrier.

3. The internally meshing planetary gear device according to claim 1 or 2, wherein The second restriction structure restricts movement of the crankshaft toward the other side in the axial direction by causing the step portion to indirectly contact the output-side carrier via a plate-shaped component.

4. The internally meshing planetary gear device according to claim 1 or 2, wherein A spacer member is interposed between the input side gear carrier and the input side cover.

5. The internally meshing planetary gear device according to claim 1 or 2, wherein The input side cover is detachably mounted to the input side gear carrier.

6. The internally meshing planetary gear device according to claim 1 or 2, wherein The crankshaft has an eccentric portion that is eccentric with respect to the axis. The first limiting structure is located axially outward of an end surface of the eccentric portion of the crankshaft, and limits movement of the crankshaft toward one side in the axial direction by causing the step portion toward the axially outward to directly or indirectly contact the input side cover.

7. The internally meshing planetary gear device according to claim 1 or 2, further comprising: An input gear, which rotates around the rotation axis; and A plurality of crankshaft gears are arranged around the input gear in a manner meshing with the input gear and rotate synchronously with each other when the input gear rotates. The crankshaft is provided with a plurality of gears in a one-to-one correspondence with the plurality of crankshaft gears. The plurality of crankshafts rotate together with the plurality of crankshaft gears, and the planetary gears oscillate around the rotation shaft.

8. A joint device for a robot, comprising: The internal meshing planetary gear device according to claim 1 or 2; a first member fixed to the gear body; and The second member rotates relative to the first member in accordance with the relative rotation of the planetary gear with respect to the internal gear.

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