Robot robot arm structure including joint device for robot and gear device

Abstract

The invention provides a robot mechanical arm structure comprising a joint device for a robot and a gear device, and relates to the technical field of robots. The gear device includes an internally toothed gear, an annular externally toothed gear, a deflection generator, and a bearing member. The deflection generator is provided with: a non-circular cam that is driven to rotate about a rotation axis; and a bearing attached to the outside of the cam. The deflection generator is disposed on the inner side of the external gear and deflects the external gear. The gear device deforms the external gear in accordance with the rotation of the cam, and causes a portion of the external teeth to engage with a portion of the internal teeth, thereby causing the external gear to rotate relative to the internal gear in accordance with a difference in the number of teeth from the internal gear. The bearing member has a first bearing member and a second bearing member that rotatably support the external gear with respect to the gear body at two locations in an axial direction parallel to the rotating shaft. Therefore, the internal teeth and the external teeth can be easily and stably meshed.

Description

Technical Field

[0001] The present invention relates to the field of robot technology, and in particular to a robot arm structure including a robot joint device and a gear device, wherein the robot joint device includes the gear device. Background Art

[0002] In the patent document Japanese Patent Publication No. 2020-153413, an internal meshing planetary gear device is known, which includes an external gear and an internal gear, and is configured in a manner that only the rotation component of the external gear is taken out (for example, see Patent Document 1). The external gear is installed in a manner that can rotate eccentrically relative to the rotation center of the input shaft. In addition, the internal gear has: a plurality of pins that rotate while meshing with each external tooth of the external gear; and a gear body (pin holder) having a cylindrical inner surface and holding each pin so that it can rotate freely.

[0003] Here, the gear body has a plurality of inner circumferential grooves (pin grooves) on the inner surface, and the inner circumferential grooves (pin grooves) are recessed in the axial direction to hold the pin. External teeth such as trochoid tooth profiles or circular arc tooth profiles are provided on the outer periphery of the external gear. The pin is a cylindrical pin member that is thin enough to bend due to the force from the external gear during rotation, and is configured in a manner that its axial direction is parallel to the center of rotation to function as an internal tooth. In addition, in the gear body in the related art, there are portions with different inner diameters (radii) in one inner circumferential groove, and in a local portion, the inner diameter of the inner circumferential groove is larger than the outer diameter of the pin, and looseness occurs due to the gap between the outer circumferential surface of the pin and the inner surface of the inner circumferential groove. Therefore, the pin can rotate with low loss.

[0004] In the above patent document, since looseness occurs between the outer circumferential surface of the pin and the inner surface of the inner circumferential groove, when the inner teeth (pin) are meshed with the outer teeth, force in the direction of pulling the outer teeth out of the inner circumferential groove acts on the pin, which may make the meshing of the inner teeth and the outer teeth unstable. Summary of the invention

[0005] An object of the present invention is to provide a robot arm structure and a gear device including a robot joint device that can easily stabilize the meshing of internal teeth and external teeth, wherein the robot joint device includes the gear device.

[0006] A robot arm structure of one form of the present invention includes a joint device for a robot, wherein the joint device for the robot includes: a gear device, including: an internal gear having: an annular gear body; and a plurality of pins, which are held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a state capable of self-rotation and constitute internal teeth; an annular external gear having external teeth and arranged on the inner side of the internal gear; a deflection generator having a non-circular cam driven to rotate around a rotating shaft and a bearing mounted on the outer side of the cam, the deflection generator being arranged on the inner side of the external gear to cause the external gear to bend; and a bearing The gear device deforms the external gear as the cam rotates, causing a portion of the external teeth to mesh with a portion of the internal teeth, thereby causing the external gear to rotate relative to the internal gear according to the difference in the number of teeth between the external gear and the internal gear, and the bearing component comprises a first bearing component and a second bearing component that support the external gear at two locations in an axial direction parallel to the rotating axis so as to be rotatable relative to the gear body; the first component is fixed to the gear body; and the second component rotates relative to the first component as the external gear rotates relative to the internal gear.

[0007] A gear device according to one aspect of the present invention includes an internal gear, an annular external gear, a deflection generator, and a bearing member. The internal gear includes: an annular gear body; and a plurality of pins, which are held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a state capable of self-rotation and constitute internal teeth. The external gear includes external teeth and is arranged on the inner side of the internal gear. The deflection generator includes a non-circular cam driven to rotate around a rotation axis, and a bearing mounted on the outer side of the cam. The deflection generator is arranged on the inner side of the external gear and causes the external gear to bend. The gear device deforms the external gear as the cam rotates, causing a portion of the external teeth to mesh with a portion of the internal teeth, thereby causing the external gear to rotate relative to the internal gear according to the difference in the number of teeth with the internal gear. The bearing member includes a first bearing member and a second bearing member that support the external gear at two locations in the axial direction parallel to the rotation axis so that the external gear can rotate relative to the gear body.

[0008] A robot joint device according to one aspect of the present invention includes: the 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.

[0009] According to the present invention, it is possible to provide a robot arm structure including a robot joint device and a gear device that can easily stabilize the meshing of internal teeth and external teeth, wherein the robot joint device includes the gear device. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a perspective view of the schematic structure of the actuator including the gear device of the basic structure 1;

[0011] Figure 2 is a schematic exploded perspective view of the gear device as viewed from the output side of the rotating shaft;

[0012] Figure 3 is a schematic cross-sectional view of the above-mentioned gear device;

[0013] Figure 4 The gear device mentioned above, Figure 3 A1-A1 line sectional view;

[0014] Figure 5A is a perspective view showing the planetary gear of the gear device as a single body;

[0015] Figure 5B is a front view showing the planetary gear of the gear device as a single body;

[0016] Fig. 6A is a perspective view showing the bearing component of the gear device as a single body;

[0017] Figure 6B is a front view showing the bearing component of the gear device as a single body;

[0018] Fig. 7A is a perspective view showing the eccentric shaft of the gear device as a single body;

[0019] Figure 7B is a front view showing the eccentric shaft of the gear device as a single body;

[0020] Fig. 8A is a perspective view showing the supporting body of the gear device as a single body;

[0021] Figure 8B is a front view showing the supporting body of the gear device as a single body;

[0022] Fig. 9 The gear device mentioned above, Figure 3 An enlarged view of area Z1;

[0023] Fig.10 The gear device mentioned above, Figure 3 B1-B1 line cross-sectional view;

[0024] Fig.11 is a schematic cross-sectional view of a gear device of basic structure II, with a schematic enlarged view of the main parts shown in the side frame;

[0025] Fig.12 The gear device mentioned above, Fig.11 One of the A1-A1 line sectional views;

[0026] Fig.13 The gear device mentioned above, Fig.11 The second section view of the A1-A1 line;

[0027] Fig.14A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 1 ;

[0028] Fig. 14B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 2 ;

[0029] Fig.15A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 3 ;

[0030] Fig. 15B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 4 ;

[0031] Fig.16A is a conceptual diagram 5 for explaining the procedure of tooth profile design of the external gear in the above-mentioned gear device;

[0032] Fig. 16B is a conceptual diagram 6 for explaining the procedure of tooth profile design of the external gear in the above-mentioned gear device;

[0033] Fig.17A is a conceptual diagram 7 for explaining the procedure of tooth profile design of the external gear in the above-mentioned gear device;

[0034] Fig. 17B FIG8 is a conceptual diagram for explaining the procedure of designing the tooth profile of the external gear in the above-mentioned gear device;

[0035] Fig.18A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 9 ;

[0036] Fig.18B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 ;

[0037] Fig.19A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 one;

[0038] Fig.19B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 two;

[0039] Fig. 20A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 three;

[0040] Fig. 20B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 Four;

[0041] Fig.21A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 five;

[0042] Fig.21B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 six;

[0043] Fig.22A This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 seven;

[0044] Fig. 22B This is a concept used to explain the order of tooth profile design of the external gear in the above-mentioned gear device. Figure 10 eight;

[0045] Fig.23 is an enlarged view of the main parts of the external teeth and the internal teeth in the above-mentioned gear device;

[0046] Fig.24 is a schematic cross-sectional view of a robot joint device using the above-mentioned gear device;

[0047] Fig.25 is a schematic cross-sectional view of the gear device of the first embodiment, and a schematic enlarged view of the main part is shown in the side frame;

[0048] Fig.26 The gear device mentioned above, Fig.25 One of the A1-A1 line sectional views;

[0049] Fig. 27 The gear device mentioned above, Fig.25The second section view of the A2-A2 line;

[0050] Fig.28 is a schematic cross-sectional view of a robot joint device (i.e., a robot arm structure) using the above-mentioned gear device;

[0051] Fig.29 This is a schematic cross-sectional view of a gear device according to a second embodiment.

[0052] Description of Reference Numerals

[0053] 1, 1A, 1B, 1C; gear device 2 internal gear; 3 external gear; 6 bearing member; 21 internal teeth; 22 gear body; 23 pin; 31 external teeth; 40 deflection generator; 41 cam; 42 bearing; 221 inner circumferential surface (of gear body); 223 inner circumferential groove; 311 tooth top; 601 first bearing member; 602 second bearing member; Ax1 rotating axis; Ra1 simultaneous meshing range. DETAILED DESCRIPTION

[0054] (Basic structure 1)

[0055] (1) Summary

[0056] For an overview of the gear device 1 of the basic structure, refer to Figure 1 to Figure 3 The drawings referred to in the present invention are schematic drawings, and the size and thickness ratios of the various structural elements in the drawings do not necessarily reflect the actual size ratios. For example, Figure 1 to Figure 3 The tooth shapes, sizes, and number of teeth of the inner teeth 21 and the outer teeth 31 are schematically shown for the purpose of explanation only, and the subject matter is not limited to the shapes shown in the drawings.

[0057] The gear device 1 of the basic structure is a gear device including an internal gear 2, an external gear 3, and a plurality of inner pins 4. In the gear device 1, the external gear 3 is arranged inside the annular internal gear 2, and further, an eccentric body bearing 5 is arranged inside the external gear 3. The eccentric body bearing 5 has an eccentric inner ring 51 and an eccentric outer ring 52. The eccentric inner ring 51 is circumferentially extending from the center C1 (refer to Figure 3 ) deviates from the rotation axis Ax1 (refer to Figure 3 ) rotates (eccentric motion), thereby causing the external gear 3 to swing. The eccentric body inner ring 51 rotates (eccentric motion) around the rotation axis Ax1, for example, by the rotation of the eccentric shaft 7 inserted into the eccentric body inner ring 51. In addition, the gear device 1 also includes a bearing component 6, and the bearing component 6 has an outer ring 62 and an inner ring 61. The inner ring 61 is arranged on the inner side of the outer ring 62 and is supported so as to be rotatable relative to the outer ring 62.

[0058] The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. In particular, in this basic structure, the internal gear 2 has an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a state capable of self-rotation to form the internal teeth 21. The external gear 3 has external teeth 31 partially meshing with the internal teeth 21. That is, on the inner side of the internal gear 2, the external gear 3 is inscribed in the internal gear 2, and a part of the external teeth 31 is in meshing with a part of the internal teeth 21. In this state, when the eccentric shaft 7 rotates, the external gear 3 swings, and the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and a relative rotation corresponding to the difference in the number of teeth between the planetary gear 3 and the internal gear 2 is generated between the two gears (the internal gear 2 and the planetary gear 3). Here, if the internal gear 2 is fixed, the external gear 3 rotates (rotates) with the relative rotation of the two gears. As a result, a rotation output reduced in speed at a relatively high reduction ratio according to the difference in the number of teeth between the two gears is obtained from the externally toothed gear 3 .

[0059] This gear device 1 is used in the following manner: the rotation of the external gear 3 corresponding to the self-rotation component is extracted as the rotation of the output shaft integrated with the inner ring 61 of the bearing member 6, for example. Thus, the gear device 1 functions as a gear device with a relatively high reduction ratio, with the eccentric shaft 7 as the input side and the output shaft as the output side. Therefore, in the gear device 1 of this basic structure, in order to transmit the rotation of the external gear 3 corresponding to the self-rotation component to the inner ring 61 of the bearing member 6, the external gear 3 and the inner ring 61 are connected by using a plurality of inner pins 4. The plurality of inner pins 4 are inserted into a plurality of inner pin holes 32 formed in the external gear 3, respectively, and rotate relative to the internal gear 2 while revolving in the inner pin holes 32. That is, the inner pin hole 32 has a larger diameter than the inner pin 4, and the inner pin 4 can move in a manner of revolving in the inner pin hole 32 while being inserted in the inner pin hole 32. Furthermore, the swing component of the external gear 3, that is, the revolution component of the external gear 3, is absorbed by the loose fit between the inner pin hole 32 of the external gear 3 and the inner pin 4. In other words, the plurality of inner pins 4 move in a manner of revolving in the plurality of inner pin holes 32, respectively, thereby absorbing the swing component of the external gear 3. Therefore, the rotation (autorotation component) of the external gear 3 in addition to the swing component (revolution component) of the external gear 3 is transmitted to the inner ring 61 of the bearing member 6 through the plurality of inner pins 4.

[0060] However, in this gear device 1, the inner pin 4 revolves in the inner pin hole 32 of the external gear 3 while transmitting the rotation of the external gear 3 to the plurality of inner pins 4, so as a first related technology, there is a known technology that uses an inner roller that is mounted on the inner pin 4 and can rotate around the inner pin 4 as an axis. That is, in the first related technology, the inner pin 4 is kept in a state of being pressed into the inner ring 61 (or a bracket integrated with the inner ring 61), and when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 slides relative to the inner circumferential surface 321 of the inner pin hole 32. Therefore, as a first related technology, an inner roller is used to reduce the loss caused by the friction resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4. However, if it is a structure including an inner roller as in the first related technology, the inner pin hole 32 needs to have a diameter that allows the inner pin 4 with the inner roller to revolve, and it is difficult to miniaturize the inner pin hole 32. If it is difficult to downsize the inner pin hole 32, it will hinder the downsizing of the external gear 3 (particularly the reduction in diameter), and even hinder the downsizing of the entire gear device 1. The gear device 1 of this basic structure can provide a gear device 1 that is easily downsized by the following structure.

[0061] That is, Figure 1 to Figure 3 As shown, the gear device 1 of this basic structure includes a bearing member 6, an internal gear 2, an external gear 3 and a plurality of inner pins 4. The bearing member 6 has an outer ring 62 and an inner ring 61 arranged on the inner side of the outer ring 62. The inner ring 61 is supported so as to be relatively rotatable relative to the outer ring 62. The internal gear 2 has internal teeth 21 and is fixed to the outer ring 62. The external gear 3 has external teeth 31 partially meshing with the internal teeth 21. The plurality of inner pins 4 are inserted into a plurality of inner pin holes 32 formed in the external gear 3, respectively, and rotate relative to the internal gear 2 while revolving in the inner pin holes 32. Here, each of the plurality of inner pins 4 is held in the inner ring 61 in a state in which it can rotate. Furthermore, each of the plurality of inner pins 4 is at least partially arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6.

[0062] According to this form, each of the plurality of inner pins 4 is held in the inner ring 61 in a state in which it can rotate, so when the inner pin 4 revolves in the inner pin hole 32, the inner pin 4 itself can rotate. Therefore, even if an inner roller that is mounted on the inner pin 4 and can rotate with the inner pin 4 as an axis is not used, the loss caused by the friction resistance between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4 can be reduced. Therefore, for the gear device 1 of this basic structure, the inner roller is not necessary, so there is an advantage of easy miniaturization. Moreover, each of the plurality of inner pins 4 is at least partially arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6, so the size of the gear device 1 in the axial direction of the bearing member 6 can be suppressed to be small. That is, compared with a structure in which the bearing member 6 and the inner pin 4 are arranged (opposed) in the axial direction of the bearing member 6, in the gear device 1 of this basic structure, the size of the gear device 1 in the axial direction can be reduced, thereby contributing to further miniaturization (thinning) of the gear device 1.

[0063] Furthermore, if the size of the external gear 3 is the same as that of the first related technology, compared with the first related technology, for example, the number of inner pins 4 can be increased to smooth the transmission of rotation, or the inner pins 4 can be thickened to improve strength.

[0064] In addition, in this gear device 1, the inner pin 4 needs to revolve in the inner pin hole 32 of the external gear 3, so as a second related technology, there is a case where multiple inner pins 4 are held only by the inner ring 61 (or a bracket integrated with the inner ring 61). According to the second related technology, it is difficult to improve the accuracy of the centering of the multiple inner pins 4, and poor centering may cause undesirable conditions such as the generation of vibration and the reduction of transmission efficiency. That is, the multiple inner pins 4 rotate relative to the internal gear 2 while revolving in the inner pin hole 32, thereby transmitting the self-rotation component of the external gear 3 to the inner ring 61 of the bearing member 6. At this time, if the rotation axes of the multiple inner pins 4 deviate or tilt relative to the rotation axis of the inner ring 61 due to insufficient centering accuracy of the multiple inner pins 4, it will become a state of poor centering, which may cause undesirable conditions such as the generation of vibration and the reduction of transmission efficiency. The gear device 1 of this basic structure can provide a gear device 1 that is unlikely to cause undesirable conditions caused by poor centering of the multiple inner pins 4 through the following structure.

[0065] That is, Figure 1 to Figure 3As shown, the gear device 1 of this basic structure includes an internal gear 2, an external gear 3, a plurality of inner pins 4 and a support body 8. The internal gear 2 has an annular gear body 22 and a plurality of pins 23. The plurality of pins 23 are held on the inner peripheral surface 221 of the gear body 22 in a state capable of rotating, thereby constituting the internal teeth 21. The external gear 3 has external teeth 31 partially meshing with the internal teeth 21. The plurality of inner pins 4 are inserted into a plurality of inner pin holes 32 formed in the external gear 3, respectively, and rotate relative to the gear body 22 while revolving in the inner pin holes 32. The support body 8 is annular and supports the plurality of inner pins 4. Here, the support body 8 is positionally restricted by bringing the outer peripheral surface 81 into contact with the plurality of pins 23.

[0066] According to this form, the plurality of inner pins 4 are supported by the annular support body 8, so the plurality of inner pins 4 are bundled by the support body 8, and the relative deviation and inclination of the plurality of inner pins 4 can be suppressed. Moreover, the outer peripheral surface 81 of the support body 8 is in contact with the plurality of pins 23, thereby limiting the position of the support body 8. In short, the support body 8 is centered by the plurality of pins 23, and as a result, the plurality of inner pins 4 supported by the support body 8 are also centered by the plurality of pins 23. Therefore, according to the gear device 1 of this basic structure, it is easy to improve the accuracy of centering of the plurality of inner pins 4, and it has the advantage that it is difficult to produce adverse conditions caused by poor centering of the plurality of inner pins 4.

[0067] In addition, if Figure 1 As shown, the gear device 1 of this basic structure and the drive source 101 together constitute the actuator 100. In other words, the actuator 100 of this basic structure includes the gear device 1 and the drive source 101. The drive source 101 generates a driving force for swinging the external gear 3. Specifically, the drive source 101 rotates the eccentric shaft 7 around the rotation axis Ax1, thereby swinging the external gear 3.

[0068] (2) Definition

[0069] The "ring-shaped" in the present invention refers to a shape that forms a circle (ring) with a space (region) surrounded 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 included in the "ring-shaped" as long as its peripheral wall is ring-shaped.

[0070] The "loose fitting" mentioned in the present invention refers to a state of being fitted with play (gap), and the inner pin hole 32 is a hole for the inner pin 4 to be loosely fitted. That is, the inner pin 4 is inserted into the inner pin hole 32 in a state where a margin of space (gap) is ensured between the inner circumferential surface 321 of the inner pin hole 32. In other words, the diameter of at least the portion of the inner pin 4 inserted into the inner pin hole 32 is smaller (thinner) than the diameter of the inner pin hole 32. Therefore, the inner pin 4 can move in the inner pin hole 32 while being inserted in the inner pin hole 32, that is, it can move relatively with respect to the center of the inner pin hole 32. As a result, the inner pin 4 can revolve in the inner pin hole 32. However, there is no need to ensure a gap as a cavity between the inner circumferential surface 321 of the inner pin hole 32 and the inner pin 4, and for example, the gap can be filled with a fluid such as a liquid.

[0071] The term "revolution" as used in the present invention 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 revolution track 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 inner pin 4 revolves in the inner pin hole 32 around the rotation axis passing through the center of the inner pin hole 32.

[0072] In addition, in the present invention, one side of the rotation axis Ax1 ( Figure 3 The left side of the rotation axis Ax1 is called the “input side”, and the other side of the rotation axis Ax1 ( Figure 3 The right side of the output is called the "output side". Figure 3 In the example, rotation is imparted to the rotating body (eccentric body inner ring 51) from the "input side" of the rotating axis Ax1, and rotation of the plurality of inner pins 4 (inner ring 61) is taken out from the "output side" of the rotating axis Ax1. However, "input side" and "output side" are merely labels given for the purpose of explanation, and their purpose does not limit the positional relationship between input and output as viewed from the gear device 1.

[0073] The "rotation axis" in the present invention refers to a virtual axis (straight line) that is the center of rotation of the rotating body. In other words, the rotation axis Ax1 is a virtual axis without a physical body. The eccentric body inner ring 51 rotates around the rotation axis Ax1.

[0074] In the present invention, the "internal teeth" and "external teeth" refer to a collection (group) of multiple "teeth" rather than a single "tooth". That is, the internal teeth 21 of the internal gear 2 is composed of 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 external gear 3 is composed of a collection of multiple teeth arranged on the outer peripheral surface of the external gear 3.

[0075] (3) Structure

[0076] For details on the structure of the gear device 1 of the basic structure, refer to Figure 1 to Figure 8B Provide explanation.

[0077] Figure 1 1 is a perspective view showing a schematic structure of an actuator 100 including a gear device 1. Figure 1 , a driving source 101 is schematically shown. Figure 2 It is a schematic exploded perspective view of the gear device 1 as viewed from the output side of the rotation axis Ax1. Figure 3 It is a schematic cross-sectional view of the gear device 1 . Figure 4 yes Figure 3 A1-A1 line section view. Figure 4 In FIG. 1 , the parts other than the eccentric shaft 7 are also cross-sectioned, but the hatching is omitted. Figure 4 In the figure, the inner peripheral surface 221 of the gear body 22 is omitted. Figure 5A and Figure 5B It is a perspective view and a front view which show the external gear 3 as a single body. Fig. 6A and Figure 6B It is a perspective view and a front view which show the bearing member 6 as a single body. Fig. 7A and Figure 7B It is a perspective view and a front view which show the eccentric shaft 7 as a single body. Fig. 8A and Figure 8B It is a perspective view and a front view which show the support body 8 as a single body.

[0078] (3.1) Overall structure

[0079] like Figure 1 to Figure 3 As shown, the gear device 1 of this basic structure includes an internal gear 2, an external gear 3, a plurality of inner pins 4, an eccentric body bearing 5, a bearing component 6, an eccentric shaft 7 and a support body 8. In addition, in this basic structure, the gear device 1 also includes a first bearing 91, a second bearing 92 and a housing 10. In this basic structure, the internal gear 2, the external gear 3, the plurality of inner pins 4, the eccentric body bearing 5, the bearing component 6, the eccentric shaft 7 and the support body 8 as structural elements of the gear device 1 are made of metals such as stainless steel, cast iron, carbon steel for mechanical structure, chrome-molybdenum steel, phosphor bronze or aluminum bronze. The metal mentioned here includes metals that have been subjected to surface treatment such as nitriding treatment.

[0080] In the present basic structure, an internal meshing planetary gear reduction 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 internal meshing external gear 3 having a trochoid tooth profile.

[0081] 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 is fixed to a fixed member such as a housing 10 together with the outer ring 62 of the bearing member 6. Thus, as the internal gear 2 and the external gear 3 rotate relative to each other, the external gear 3 rotates relative to the fixed member (housing 10, etc.).

[0082] Furthermore, in this basic structure, when the gear device 1 is used for the actuator 100, by applying a rotational force as an input to the eccentric shaft 7, a rotational force as an output is taken out from the output shaft integrated with the inner ring 61 of the bearing member 6. That is, the gear device 1 operates with the rotation of the eccentric shaft 7 as the input rotation and the rotation of the output shaft integrated with the inner ring 61 as the output rotation. As a result, in the gear device 1, an output rotation that is reduced by a relatively high reduction ratio relative to the input rotation can be obtained.

[0083] The driving source 101 is a power generating source such as an electric motor. The power generated by the driving source 101 is transmitted to the eccentric shaft 7 in the gear device 1. Specifically, the driving source 101 is connected to the eccentric shaft 7 via an input shaft, and the power generated by the driving source 101 is transmitted to the eccentric shaft 7 via the input shaft. Thus, the driving source 101 can rotate the eccentric shaft 7.

[0084] Further, in the gear device 1 of this basic structure, as Figure 3 As shown, the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are 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 eccentric shaft 7 to which the input rotation is given, and the rotation axis Ax1 on the output side is the rotation center of the inner ring 61 (and the output shaft) that generates the output rotation. That is, in the gear device 1, it is possible to obtain an output rotation that is reduced at a relatively high reduction ratio on the same axis relative to the input rotation.

[0085] like Figure 4 As shown, the internal gear 2 is an annular component 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 intervals over the entire area of ​​the inner circumferential direction of the internal gear 2. In other words, 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 on the rotation axis Ax1. In addition, the internal gear 2 has a specified thickness along the direction of the rotation axis Ax1. The tooth directions of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth direction is slightly smaller than that in the thickness direction of the internal gear 2.

[0086] Here, as described above, the internal gear 2 has an annular (ring-shaped) gear body 22 and a plurality of pins 23. The plurality of pins 23 are held on the inner peripheral surface 221 of the gear body 22 in a rotatable state, and constitute the internal teeth 21. In other words, the plurality of pins 23 function as a plurality of teeth constituting the internal teeth 21. Specifically, Figure 2 As shown, a plurality of inner circumferential grooves 223 are formed on the inner circumferential surface 221 of the gear body 22 over 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 intervals. The plurality of inner circumferential grooves 223 are all parallel to the rotation axis Ax1 and are formed over the entire length of the thickness direction of the gear body 22. The plurality of pins 23 are combined with the gear body 22 in a manner of being embedded in the plurality of inner circumferential grooves 223. Each of the plurality of pins 23 is maintained in a state of being able to rotate within the inner circumferential grooves 223. In addition, the gear body 22 (together with the outer ring 62) is fixed to the housing 10. Therefore, a plurality of fixing holes 222 for fixing are formed in the gear body 22.

[0087] like Figure 4 As shown, the external gear 3 is an annular component having external teeth 31. In this basic structure, the external 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 external gear 3, external teeth 31 are formed along the circumferential direction of the external gear 3. The plurality of teeth constituting the external teeth 31 are all of the same shape and are arranged at equal intervals over the entire area of ​​the outer peripheral surface of the external gear 3 in the circumferential direction. In other words, the pitch circle of the external teeth 31 is a perfect circle when viewed from above. The center C1 of the pitch circle of the external teeth 31 is located at a distance ΔL (refer to Figure 4 ) position. In addition, the external gear 3 has a predetermined thickness in the direction of the rotation axis Ax1. The external teeth 31 are formed over the entire length of the external gear 3 in the thickness direction. The tooth directions of the external teeth 31 are parallel to the rotation axis Ax1. In the external gear 3, unlike the internal gear 2, the external teeth 31 and the main body of the external gear 3 are formed integrally by a metal member.

[0088] Here, the external gear 3 is combined with an eccentric body bearing 5 and an eccentric shaft 7. That is, an opening portion 33 with a circular opening is formed in the external gear 3. The opening portion 33 is a hole that penetrates the external gear 3 along the thickness direction. When viewed from above, the center of the opening portion 33 coincides with the center of the external gear 3, and the inner peripheral surface of the opening portion 33 (the inner peripheral surface of the external gear 3) is concentric with the pitch circle of the external teeth 31. The eccentric body bearing 5 is accommodated in the opening portion 33 of the external gear 3. Furthermore, the eccentric body bearing 5 and the eccentric shaft 7 are combined with the external gear 3 by inserting the eccentric shaft 7 into the eccentric body bearing 5 (the eccentric body inner ring 51). In a state where the external gear 3 is combined with the eccentric body bearing 5 and the eccentric shaft 7, when the eccentric shaft 7 rotates, the external gear 3 swings around the rotation axis Ax1.

[0089] The external gear 3 thus constructed is arranged inside the internal gear 2. In a plan view, the external gear 3 is formed to be one size smaller than the internal gear 2, and the external gear 3 can swing inside the internal gear 2 when combined with the internal gear 2. At this time, external teeth 31 are formed on the outer peripheral surface of the external gear 3, and internal teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the external gear 3 is arranged inside the internal gear 2, the external teeth 31 and the internal teeth 21 are opposite to each other.

[0090] Furthermore, the pitch circle of the external teeth 31 is one circle smaller than the pitch circle of the internal teeth 21. In addition, when the external gear 3 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 is offset from the center of the pitch circle of the internal teeth 21 (rotation axis Ax1) by a distance ΔL (refer to Figure 4 ) position. Therefore, the outer teeth 31 and at least a part of the inner teeth 21 are opposite to each other with a gap, and there is no overall meshing with each other in the circumferential direction. However, the outer gear 3 swings (revolves) around the rotation axis Ax1 inside the inner gear 2, so the outer teeth 31 and the inner teeth 21 are partially meshed. In other words, by the outer gear 3 swinging around the rotation axis Ax1, as shown in Figure 4 As shown, some of the teeth constituting the external teeth 31 mesh with some of the 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.

[0091] 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 external gear 3. In this basic structure, as an example, N is "1", and the number of teeth of the external gear 3 (external teeth 31) is "1" greater than the number of teeth of the internal gear 2 (internal teeth 21). Such a difference in the number of teeth between the external gear 3 and the internal gear 2 defines the reduction ratio of the output rotation relative to the input rotation in the gear device 1.

[0092] In addition, in this basic structure, as an example, the thickness of the external gear 3 is smaller than the thickness of the gear body 22 in the internal gear 2. Furthermore, the dimension of the tooth direction (direction parallel to the rotation axis Ax1) of the external teeth 31 is smaller than the dimension of the tooth 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 are within the range of the tooth direction of the internal teeth 21.

[0093] In this basic structure, as described above, the rotation of the external gear 3 corresponding to the self-rotation component is taken out as the rotation (output rotation) of the output shaft integrated with the inner ring 61 of the bearing member 6. Therefore, the external gear 3 is connected to the inner ring 61 by a plurality of inner pins 4. Figure 5A and Figure 5BAs shown, a plurality of inner pin holes 32 for inserting a plurality of inner pins 4 are formed in the external gear 3. The same number of inner pin holes 32 as the number of inner pins 4 is provided. In this basic structure, as an example, 18 inner pin holes 32 and 18 inner pins 4 are provided. Each of the plurality of inner pin holes 32 is a hole that opens in a circular shape and penetrates the external gear 3 in the thickness direction. The plurality of (here, 18) inner pin holes 32 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the opening 33.

[0094] The inner pins 4 are components that connect the external gear 3 to the inner ring 61 of the bearing member 6. Each of the inner pins 4 is formed in a cylindrical shape. The diameter and length of the inner pins 4 are the same among the inner pins 4. The diameter of the inner pin 4 is one circle smaller than the diameter of the inner pin hole 32. Thus, the inner pin 4 is inserted into the inner pin hole 32 (see FIG. 1 ) in a state where a margin of space (clearance) is ensured between the inner peripheral surface 321 of the inner pin hole 32. Figure 4 ).

[0095] The bearing member 6 is a component having an outer ring 62 and an inner ring 61 and is used to extract the output of the gear device 1 as the rotation of the inner ring 61 relative to the outer ring 62. The bearing member 6 has a plurality of rolling elements 63 (see Figure 3 ).

[0096] like Fig. 6A and Figure 6B As shown, the outer ring 62 and the inner ring 61 are both annular components. The outer ring 62 and the inner ring 61 both have an annular shape that is a perfect circle when viewed from above. The inner ring 61 is one circle smaller than the outer ring 62 and is arranged on the inner side of the outer ring 62. Here, the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, so a gap is generated between the inner peripheral surface of the outer ring 62 and the outer peripheral surface of the inner ring 61.

[0097] The inner ring 61 has a plurality of retaining holes 611 for inserting a plurality of inner pins 4. The retaining holes 611 are provided in the same number as the inner pins 4. In this basic structure, as an example, 18 retaining holes 611 are provided. Fig. 6A and Figure 6B As shown, each of the plurality of retaining holes 611 is a hole that opens in a circular shape and penetrates the inner ring 61 in the thickness direction. The plurality of (here, 18) retaining holes 611 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer circumference of the inner ring 61. The diameter of the retaining hole 611 is greater than the diameter of the inner pin 4 and smaller than the diameter of the inner pin hole 32.

[0098] Furthermore, the inner ring 61 is integrated with the output shaft, and the rotation of the inner ring 61 is taken as the rotation of the output shaft. Therefore, a plurality of output side mounting holes 612 (see FIG. 1 ) for mounting the output shaft are formed in the inner ring 61. Figure 2). In this basic structure, the plurality of output-side mounting holes 612 are located inside the plurality of retaining holes 611 and are arranged on a virtual circle that is concentric with the outer circumference of the inner ring 61 .

[0099] The outer ring 62 is fixed to a fixed member such as a housing 10 together with the gear body 22 of the internal gear 2. Therefore, a plurality of through holes 621 for fixing are formed in the outer ring 62. Specifically, Figure 3 As shown, the outer ring 62 is fixed to the housing 10 by fixing screws (bolts) 60 passing through the through holes 621 and the fixing holes 222 of the gear body 22 , with the gear body 22 sandwiched between the outer ring 62 and the housing 10 .

[0100] The plurality of rolling elements 63 are arranged in the gap between the outer ring 62 and the inner ring 61. The plurality of rolling elements 63 are arranged in a row along the circumferential direction of the outer ring 62. The plurality of rolling elements 63 are all metal parts of the same shape and are arranged at equal intervals over the entire circumferential area of ​​the outer ring 62.

[0101] In this basic structure, as an example, the bearing component 6 is a cross roller bearing. That is, the bearing component 6 has a cylindrical roller as a rolling element 63. And the axis of the cylindrical rolling element 63 has an inclination of 45 degrees relative to the plane orthogonal to the rotation axis Ax1, and is orthogonal to the outer periphery of the inner ring 61. Furthermore, a pair of rolling elements 63 adjacent to each other in the circumferential direction of the inner ring 61 are arranged in directions orthogonal to each other in the axial direction. In such a bearing component 6 composed of a cross roller bearing, radial loads, loads in the thrust direction (along the direction of the rotation axis Ax1), and bending forces (bending moment loads) with respect to the rotation axis Ax1 are all easily borne. Moreover, through a single bearing component 6, these three loads can be tolerated, thereby ensuring the required rigidity.

[0102] like Fig. 7A and Figure 7B As shown, the eccentric shaft 7 is a cylindrical component. The eccentric shaft 7 has an axial portion 71 and an eccentric portion 72. The axial portion 71 has a cylindrical shape with at least the outer peripheral surface being a perfect circle when viewed from above. The center (central axis) of the axial portion 71 coincides with the rotation axis Ax1. The eccentric portion 72 has a disc shape with at least the outer peripheral surface being a perfect circle when viewed from above. The center (central axis) of the eccentric portion 72 coincides with the center C1 deviated from the rotation axis Ax1. Here, the distance ΔL (refer to Figure 7B ) 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 all around the central portion in the length direction (axial direction) of the axial portion 71. According to the above structure, for the eccentric shaft 7, the eccentric portion 72 performs eccentric motion by the axial portion 71 rotating (rotating) around the rotation axis Ax1.

[0103] In this basic structure, the shaft center portion 71 and the eccentric portion 72 are integrally formed by one metal member, thereby realizing a seamless eccentric shaft 7. The eccentric shaft 7 of such a shape is combined with the eccentric body bearing 5 to the planetary gear 3. Therefore, in a state where the external gear 3 is combined with the eccentric body bearing 5 and the eccentric shaft 7, when the eccentric shaft 7 rotates, the external gear 3 swings around the rotation axis Ax1.

[0104] Furthermore, the eccentric shaft 7 has a through hole 73 that penetrates the shaft core portion 71 in the axial direction (length direction). The through hole 73 is circularly opened at both end faces in the axial direction of the shaft core portion 71. The center (central axis) of the through hole 73 coincides with the rotation axis Ax1. For example, cables such as power lines and signal lines can pass through the through hole 73.

[0105] In addition, in this basic structure, the rotational force as input is applied from the driving source 101 to the eccentric shaft 7. Therefore, the eccentric shaft 7 is formed with a plurality of input side mounting holes 74 (see Fig. 7A and Figure 7B In this basic structure, a plurality of input-side mounting holes 74 are arranged around the through hole 73 on one end surface along the axial direction of the shaft core portion 71 and on a virtual circle concentric with the through hole 73 .

[0106] The eccentric bearing 5 is a component that has an eccentric outer ring 52 and an eccentric inner ring 51, absorbs the rotational component of the eccentric shaft 7, and transmits only the rotation of the eccentric shaft 7 other than the rotational component of the eccentric shaft 7, that is, the swing component (revolution component) of the eccentric shaft 7 to the external gear 3. The eccentric bearing 5 has a plurality of rolling elements 53 (see FIG. 1 ) in addition to the eccentric outer ring 52 and the eccentric inner ring 51. Figure 3 ).

[0107] The eccentric outer ring 52 and the eccentric inner ring 51 are both annular components. The eccentric outer ring 52 and the eccentric inner ring 51 both have an annular shape that is a perfect circle when viewed from above. The eccentric inner ring 51 is one circle smaller than the eccentric outer ring 52 and is arranged on the inner side of the eccentric outer ring 52. Here, the inner diameter of the eccentric outer ring 52 is larger than the outer diameter of the eccentric inner ring 51, so a gap is generated between the inner peripheral surface of the eccentric outer ring 52 and the outer peripheral surface of the eccentric inner ring 51.

[0108] A plurality of rolling elements 53 are arranged in the gap between the eccentric outer ring 52 and the eccentric inner ring 51. The plurality of rolling elements 53 are arranged in a row along the circumferential direction of the eccentric outer ring 52. The plurality of rolling elements 53 are all metal parts of the same shape and are arranged at equal intervals in the entire area of ​​the eccentric outer ring 52 in the circumferential direction. In this basic structure, as an example, the eccentric body bearing 5 is composed of a deep groove ball bearing using balls as the rolling elements 53.

[0109] Here, the inner diameter of the eccentric body inner ring 51 is consistent with the outer diameter of the eccentric portion 72 in the eccentric shaft 7. The eccentric body bearing 5 is combined with the eccentric shaft 7 in a state where the eccentric portion 72 of the eccentric shaft 7 is inserted into the eccentric body inner ring 51. In addition, the outer diameter of the eccentric body outer ring 52 is consistent with the inner diameter (diameter) of the opening portion 33 in the external gear 3. The eccentric body bearing 5 is combined with the external gear 3 in a state where the eccentric body outer ring 52 is embedded in the opening portion 33 of the external gear 3. In other words, the eccentric body bearing 5 in a state where the eccentric portion 72 assembled to the eccentric shaft 7 is accommodated in the opening portion 33 of the external gear 3.

[0110] In addition, in this basic structure, as an example, the dimension of the eccentric body inner ring 51 in the eccentric body bearing 5 in the width direction (direction parallel to the rotation axis Ax1) is substantially the same as the thickness of the eccentric portion 72 of the eccentric shaft 7. The dimension of the eccentric body outer ring 52 in the width direction (direction parallel to the rotation axis Ax1) is slightly smaller than the dimension of the eccentric body inner ring 51 in the width direction. Furthermore, the dimension of the eccentric body outer ring 52 in the width direction is larger than the thickness of the external gear 3. Therefore, in the direction parallel to the rotation axis Ax1, the external gear 3 is accommodated within the range of the eccentric body bearing 5. On the other hand, the dimension of the eccentric body outer ring 52 in the width direction is smaller than the dimension of the internal teeth 21 in the tooth direction (direction parallel to the rotation axis Ax1). Therefore, in the direction parallel to the rotation axis Ax1, the eccentric body bearing 5 is accommodated within the range of the internal gear 2.

[0111] In a state where the eccentric body bearing 5 and the eccentric shaft 7 are combined with the external gear 3, when the eccentric shaft 7 rotates, in the eccentric body bearing 5, the eccentric body inner ring 51 rotates around the rotation axis Ax1 deviated from the center C1 of the eccentric body inner ring 51 (eccentric motion). At this time, the rotation component of the eccentric shaft 7 is absorbed by the eccentric body bearing 5. Therefore, only the rotation of the eccentric shaft 7 other than the rotation component of the eccentric shaft 7, that is, the swing component (revolution component) of the eccentric shaft 7 is transmitted to the external gear 3 through the eccentric body bearing 5. Therefore, in a state where the external gear 3 is combined with the eccentric body bearing 5 and the eccentric shaft 7, when the eccentric shaft 7 rotates, the external gear 3 swings around the rotation axis Ax1.

[0112] like Fig. 8A and Figure 8B As shown, the support body 8 is a member formed in an annular shape and supports a plurality of inner pins 4. The support body 8 has a plurality of supporting holes 82 for inserting the plurality of inner pins 4. The number of the supporting holes 82 is the same as the number of the inner pins 4. In this basic structure, as an example, 18 supporting holes 82 are provided. Fig. 8A and Figure 8BAs shown, each of the plurality of support holes 82 is a hole that opens in a circular shape and penetrates the support body 8 in the thickness direction. A plurality of (here, 18) support holes 82 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer peripheral surface 81 of the support body 8. The diameter of the support hole 82 is greater than the diameter of the inner pin 4 and smaller than the diameter of the free fitting hole 32. In this basic structure, as an example, the diameter of the support hole 82 is equal to the diameter of the retaining hole 611 formed in the inner ring 61.

[0113] like Figure 3 As shown, the support body 8 is arranged in a manner opposite to the external gear 3 from one side (input side) of the rotation axis Ax1. And, by inserting a plurality of inner pins 4 into a plurality of support holes 82, the support body 8 functions in a manner of bundling the plurality of inner pins 4. Furthermore, the support body 8 is positionally restricted by bringing the outer peripheral surface 81 into contact with the plurality of pins 23. Thus, the support body 8 is centered by the plurality of pins 23, and as a result, the plurality of inner pins 4 supported by the supported body 8 are also centered by the plurality of pins 23. The support body 8 is described in detail in the "(3.3) Support body" column.

[0114] The first bearing 91 and the second bearing 92 are respectively mounted on the axial center portion 71 of the eccentric shaft 7. Figure 3 As shown, the first bearing 91 and the second bearing 92 are mounted on both sides of the eccentric portion 72 in the shaft portion 71 in such a manner as to sandwich the eccentric portion 72 in a direction parallel to the rotation axis Ax1. When viewed from the eccentric portion 72, the first bearing 91 is arranged on the input side of the rotation axis Ax1. When viewed from the eccentric portion 72, the second bearing 92 is arranged on the output side of the rotation axis Ax1. The first bearing 91 holds the eccentric shaft 7 so as to be rotatable relative to the housing 10. The second bearing 92 holds the eccentric shaft 7 so as to be rotatable relative to the inner ring 61 of the bearing member 6. Thus, the shaft portion 71 of the eccentric shaft 7 is held rotatable at two locations on both sides of the eccentric portion 72 in a direction parallel to the rotation axis Ax1.

[0115] The housing 10 is cylindrical and has a flange 11 on the output side of the rotation axis Ax1. A plurality of setting holes 111 for fixing the housing 10 itself are formed in the flange 11. In addition, a bearing hole 12 is formed on the end surface of the housing 10 on the output side of the rotation axis Ax1. The bearing hole 12 is open in a circular shape. The first bearing 91 is mounted on the housing 10 by inserting the first bearing 91 into the bearing hole 12.

[0116] In addition, a plurality of threaded holes 13 are formed on the end surface of the housing 10 on the output side of the rotation axis Ax1 and around the bearing hole 12. The plurality of threaded holes 13 are used to fix the gear body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 to the housing 10. Specifically, the fixing screws 60 are passed through the through holes 621 of the outer ring 62 and the fixing holes 222 of the gear body 22 and are tightened into the threaded holes 13, thereby fixing the gear body 22 and the outer ring 62 to the housing 10.

[0117] In addition, if Figure 3 As shown, the gear device 1 of this basic structure also includes a plurality of oil seals 14, 15, 16, etc. The oil seal 14 is mounted on the end of the input side of the rotation axis Ax1 of the eccentric shaft 7, and fills the gap between the housing 10 and the eccentric shaft 7 (axial center portion 71). The oil seal 15 is mounted on the end of the output side of the rotation axis Ax1 of the eccentric shaft 7, and fills the gap between the inner ring 61 and the eccentric shaft 7 (axial center portion 71). The oil seal 16 is mounted on the end face of the output side of the rotation axis Ax1 of the bearing member 6, and fills the gap between the inner ring 61 and the outer ring 62. The space enclosed by these multiple oil seals 14, 15, 16 constitutes a lubricant retaining space 17 (refer to Fig. 9 The lubricant retaining space 17 includes a space between the inner ring 61 and the outer ring 62 of the bearing member 6. Furthermore, the lubricant retaining space 17 contains a plurality of pins 23, the external gear 3, the eccentric bearing 5, the support body 8, the first bearing 91, the second bearing 92, and the like.

[0118] Furthermore, a lubricant is sealed in 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, for example, the lubricant enters the meshing portion between the internal teeth 21 composed of a plurality of pins 23 and the external teeth 31 of the external gear 3. The "liquid" mentioned in the present invention refers to a substance containing a liquid or gel state. The "gel state" mentioned here refers to a state having intermediate properties between a liquid and a solid, and contains a colloid state composed of two phases, a liquid phase and a solid phase. For example, an emulsion (emulsion) in which the dispersant is a liquid phase and the dispersant is a liquid phase, a suspension (suspension) in which the dispersant is a solid phase, etc. are called gel (gel) or sol (sol) and are included in the "gel state". In addition, a state in which the dispersant is a solid phase and the dispersant is a liquid phase is also included in the "gel state". In this basic structure, as an example, the lubricant is a liquid lubricating oil (oil).

[0119] In the gear device 1 of the above-mentioned structure, a rotational force is applied as an input to the eccentric shaft 7, so that the eccentric shaft 7 rotates around the rotation axis Ax1, and the external gear 3 swings (revolves) around the rotation axis Ax1. At this time, the external gear 3 swings in a state where it is inscribed in the inner side of the internal gear 2 and a part of the external teeth 31 meshes 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 external gear 3 and the internal gear 2 is generated between the two gears (the internal gear 2 and the external gear 3). In addition, the rotation (autorotation component) of the external gear 3 in addition to the swing component (revolution component) of the external gear 3 is transmitted to the inner ring 61 of the bearing member 6 through the plurality of inner pins 4. As a result, a rotation output reduced by a relatively high reduction ratio corresponding to the difference in the number of teeth between the two gears can be obtained from the output shaft integrated with the inner ring 61.

[0120] However, as described above, in the gear device 1 of this basic structure, the difference in the number of teeth between the internal gear 2 and the external gear 3 defines 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 rigid internal gear 2 is set to "V1" and the number of teeth of the external gear 3 is set to "V2", the reduction ratio R1 is expressed by the following formula 1.

[0121] R1=V2 / (V1-V2)……(Formula 1)

[0122] In short, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the external gear 3 is, the greater the reduction ratio R1 is. For example, since the number of teeth V1 of the internal gear 2 is "52" and the number of teeth V2 of the external gear 3 is "51", the difference in the number of teeth (V1-V2) is "1", so according to the above formula 1, the reduction ratio R1 is "51". In this case, when the eccentric shaft 7 rotates clockwise around the rotation axis Ax1 for one circle (360 degrees) when viewed from the input side of the rotation axis Ax1, the inner ring 61 rotates counterclockwise around the rotation axis Ax1 by the difference in the number of teeth "1" (that is, about 7.06 degrees).

[0123] According to the gear device 1 of this basic structure, such a high reduction ratio R1 can be achieved by the combination of the primary gears (the internal gear 2 and the external gear 3).

[0124] The gear device 1 only needs to include at least the internal gear 2 , the external gear 3 , the plurality of inner pins 4 , the bearing member 6 , and the support body 8 , and may further include, for example, a spline bushing as a component.

[0125] However, in the case where the input rotation of the high-speed rotating side is accompanied by eccentric motion as in the gear device 1 of this basic structure, if the balance of the rotating body rotating at high speed is not achieved, vibration may occur, so sometimes a balance weight is used to achieve weight balance. That is, the rotating body composed of the eccentric body inner ring 51 and at least one of the components (eccentric shaft 7) that rotates together with the eccentric body inner ring 51 performs eccentric motion at high speed, so it is preferable to achieve weight balance of the rotating body relative to the rotation axis Ax1. In this basic structure, Figure 3 and Figure 4 As shown, by providing a gap 75 in a part of the eccentric portion 72 of the eccentric shaft 7, the weight balance of the rotating body with respect to the rotation axis Ax1 is achieved.

[0126] In summary, in this basic structure, the weight of the rotating body (here, the eccentric shaft 7) is reduced by thinning a portion of the rotating body without adding a balancing weight, thereby achieving a weight balance of the rotating body relative to the rotating axis Ax1. That is, the gear device 1 of this basic structure includes an eccentric body bearing 5 that is accommodated in an opening portion 33 formed in the external gear 3 and causes the external gear 3 to swing. The eccentric body bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51 that is arranged on the inner side of the eccentric outer ring 52. The rotating body composed of the eccentric inner ring 51 and at least one of the components that rotate with the eccentric inner ring 51 has a gap 75 on a portion of the eccentric outer ring 52 on the side of the center C1 when viewed from the rotating axis Ax1 of the eccentric inner ring 51. In this basic structure, the eccentric shaft 7 is a "component that rotates with the eccentric inner ring 51" and is equivalent to a "rotating body". Therefore, the gap 75 formed in the eccentric portion 72 of the eccentric shaft 7 is equivalent to the gap 75 of the rotating body. As Figure 3 and Figure 4 As shown, the gap 75 is located on the center C1 side when viewed from the rotation axis Ax1, and thus functions to make the weight balance of the eccentric shaft 7 nearly uniform from the rotation axis Ax1 to the circumferential direction.

[0127] In more detail, the gap 75 includes a recessed portion formed on the inner circumferential surface of the through hole 73 that penetrates the rotating body along the rotation axis Ax1 of the eccentric body inner ring 51. That is, in this basic structure, the rotating body is the eccentric shaft 7, so the recessed portion formed on the inner circumferential surface of the through hole 73 that penetrates the eccentric shaft 7 along the rotation axis Ax1 functions as the gap 75. In this way, by utilizing the recessed portion formed on the inner circumferential surface of the through hole 73 as the gap 75, the weight balance of the rotating body can be achieved without changing the appearance.

[0128] (3.2) Rotational structure of domestic sales

[0129] Next, regarding the self-rotation structure of the inner pin 4 of the gear device 1 of the basic structure, refer to Fig. 9 for a more detailed description. Fig. 9 yes Figure 3 A magnified view of area Z1.

[0130] First, as a premise, as described above, the plurality of inner pins 4 are components that connect the external gear 3 to the inner ring 61 of the bearing member 6. Specifically, one end of the inner pin 4 in the length direction (the end on the input side of the rotation axis Ax1 in this basic structure) is inserted into the loose fitting hole 32 of the external gear 3, and the other end of the inner pin 4 in the length direction (the end on the output side of the rotation axis Ax1 in this basic structure) is inserted into the retaining hole 611 of the inner ring 61.

[0131] Here, the diameter of the inner pin 4 is one circle smaller than the diameter of the free fitting hole 32, so that a gap can be ensured between the inner pin 4 and the inner peripheral surface 321 of the free fitting hole 32, and the inner pin 4 can move in the free fitting hole 32, that is, it can move relatively to the center of the free fitting hole 32. On the other hand, although the diameter of the retaining hole 611 is larger than the diameter of the inner pin 4, it is smaller than the diameter of the free fitting hole 32. In this basic structure, the diameter of the retaining hole 611 is approximately the same as the diameter of the inner pin 4, and is slightly larger than the diameter of the inner pin 4. Therefore, the movement of the inner pin 4 in the retaining hole 611 is restricted, that is, the relative movement of the inner pin 4 relative to the center of the retaining hole 611 is prohibited. Therefore, for the inner pin 4, it is retained in the external gear 3 in a state where it can revolve in the free fitting hole 32, and is retained in a state where it cannot revolve in the retaining hole 611 relative to the inner ring 61. As a result, the swing component of the external gear 3, that is, the revolution component of the external gear 3 is absorbed by the loose fitting between the loose fitting hole 32 and the inner pin 4, and the rotation (autorotation component) of the external gear 3 in addition to the swing component (revolution component) of the external gear 3 is transmitted to the inner ring 61 through multiple inner pins 4.

[0132] However, in this basic structure, the diameter of the inner pin 4 is slightly larger than the retaining hole 611, so that when the inner pin 4 is inserted into the retaining hole 611, although the revolution in the retaining hole 611 is prohibited, it can rotate in the retaining hole 611. In other words, even if the inner pin 4 is inserted into the retaining hole 611, it can rotate in the retaining hole 611 because it is not pressed into the retaining hole 611. In this way, in the gear device 1 of this basic structure, the multiple inner pins 4 are each retained by the inner ring 61 in a state in which they can rotate, so when the inner pin 4 revolves in the loose hole 32, the inner pin 4 itself can rotate.

[0133] In summary, in this basic structure, the inner pin 4 is held relative to the external gear 3 in a state in which it can both revolve and rotate within the free fitting hole 32, and is held relative to the inner ring 61 in a state in which it can only rotate within the retaining hole 611. That is, the plurality of inner pins 4 can rotate (revolve) around the rotation axis Ax1 in a state in which their respective rotations are not constrained (a state in which they can rotate), and can revolve within the plurality of free fitting holes 32. Therefore, when the rotation (rotation component) of the external gear 3 is transmitted to the inner ring 61 by means of the plurality of inner pins 4, the inner pin 4 can revolve and rotate within the free fitting hole 32, and can rotate within the retaining hole 611. Therefore, when the inner pin 4 revolves within the free fitting hole 32, the inner pin 4 is in a state in which it can rotate, and therefore rolls relative to the inner circumferential surface 321 of the free fitting hole 32. In other words, the inner pin 4 revolves in the free fitting hole 32 by rolling on the inner peripheral surface 321 of the free fitting hole 32 , so that loss due to friction resistance between the inner peripheral surface 321 of the free fitting hole 32 and the inner pin 4 is unlikely to occur.

[0134] Thus, in the structure of this basic structure, since it is difficult to generate the loss caused by the friction resistance between the inner circumferential surface 321 of the free fitting hole 32 and the inner pin 4, the inner roller can be omitted. Therefore, in this basic structure, each of the plurality of inner pins 4 adopts a structure that directly contacts the inner circumferential surface 321 of the free fitting hole 32. That is, in this basic structure, the inner pin 4 in the state of not being equipped with the inner roller is inserted into the free fitting hole 32 so that the inner pin 4 directly contacts the inner circumferential surface 321 of the free fitting hole 32. Thus, the inner roller can be omitted, and the diameter of the free fitting hole 32 can be suppressed to be relatively small, so that the external gear 3 can be miniaturized (especially reduced in diameter), and the gear device 1 as a whole can also be easily miniaturized. If the size of the external gear 3 is set to be fixed, then compared with the first related technology mentioned above, for example, the number (number of roots) of the inner pins 4 can be increased to make the transmission of rotation smooth, or the inner pins 4 can be thickened to increase the strength. Furthermore, the number of components can be reduced by the amount of the inner roller, which also contributes to cost reduction of the gear device 1 .

[0135] In addition, in the gear device 1 of the present basic structure, at least a portion of each of the plurality of inner pins 4 is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6. Fig. 9As shown, in a direction parallel to the rotation axis Ax1, the inner pin 4 is arranged at least a portion thereof at the same position as the bearing member 6. In other words, at least a portion of the inner pin 4 is located between the two end surfaces of the bearing member 6 in a direction parallel to the rotation axis Ax1. In other words, at least a portion of each of the plurality of inner pins 4 is arranged on the inner side of the outer ring 62 of the bearing member 6. In this basic structure, the end portion of the inner pin 4 on the output side of the rotation axis Ax1 is located at the same position as the bearing member 6 in a direction parallel to the rotation axis Ax1. In short, the end portion of the inner pin 4 on the output side of the rotation axis Ax1 is inserted into the retaining hole 611 formed in the inner ring 61 of the bearing member 6, so at least the end portion is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6.

[0136] In this way, at least a portion of each of the plurality of inner pins 4 is arranged at the same position as the bearing member 6 in the axial direction of the bearing member 6, thereby making it possible to suppress the size of the gear device 1 in the direction parallel to the rotation axis Ax1 to be small. That is, compared with a structure in which the bearing member 6 and the inner pin 4 are arranged (opposed) in the axial direction of the bearing member 6, in the gear device 1 of this basic structure, the size of the gear device 1 in the direction parallel to the rotation axis Ax1 can be reduced, and it is possible to contribute to further miniaturization (thinning) of the gear device 1.

[0137] Here, the opening surface of the holding hole 611 on the output side of the rotation axis Ax1 is closed by, for example, an output shaft integrated with the inner ring 61. Fig. 9 The movement of the right side of the inner ring 61 is restricted by the output shaft integrated with the inner ring 61.

[0138] In addition, in this basic structure, the following structure is adopted to make the inner pin 4 rotate smoothly relative to the inner ring 61. That is, the inner pin 4 rotates smoothly by interposing a lubricant (lubricating oil) between the inner peripheral surface of the retaining hole 611 formed in the inner ring 61 and the inner pin 4. In particular, in this basic structure, there is a lubricant retaining space 17 for injecting lubricant between the inner ring 61 and the outer ring 62, so the lubricant in the lubricant retaining space 17 is used to realize the smooth rotation of the inner pin 4.

[0139] like Fig. 9As shown, in this basic structure, the inner ring 61 has: a plurality of retaining holes 611 for inserting a plurality of inner pins 4 respectively; and a plurality of connecting paths 64. The plurality of connecting paths 64 connect the lubricant retaining space 17 between the inner ring 61 and the outer ring 62 with the plurality of retaining holes 611. Specifically, the inner ring 61 is provided with connecting paths 64 extending radially from a portion of the inner circumferential surface of the retaining hole 611, i.e., a portion corresponding to the rolling element 63. The connecting paths 64 are holes that pass through the bottom surface of the recess (groove) for accommodating the rolling element 63 in the inner ring 61 facing the outer ring 62 and the inner circumferential surface of the retaining hole 611. In other words, the opening surface of the connecting path 64 on the lubricant retaining space 17 side is arranged at a position facing (opposite) the rolling element 63 of the bearing member 6. The lubricant retaining space 17 and the retaining hole 611 are spatially connected via such connecting paths 64.

[0140] According to the above structure, since the lubricant retaining space 17 is connected to the retaining hole 611 by the connecting path 64, the lubricant in the lubricant retaining space 17 passes through the connecting path 64 and is supplied to the retaining hole 611. That is, when the bearing member 6 moves and the rolling element 63 rolls, the rolling element 63 functions as a pump and can send the lubricant in the lubricant retaining space 17 to the retaining hole 611 via the connecting path 64. In particular, the opening surface of the connecting path 64 on the lubricant retaining space 17 side is located in a position facing (opposite) to the rolling element 63 of the bearing member 6, so that the rolling element 63 effectively functions as a pump when the rolling element 63 rotates. As a result, the lubricant is interposed between the inner circumferential surface of the retaining hole 611 and the inner pin 4, and the inner pin 4 can smoothly rotate relative to the inner ring 61.

[0141] (3.3) Support body

[0142] Next, regarding the structure of the support body 8 of the gear device 1 of this basic structure, refer to Fig.10 This will be described in more detail. Fig.10 yes Figure 3 However, in Fig.10 In the figure, the hatching is omitted even in the cross section for the components other than the support body 8. Fig.10 In the figure, only the internal gear 2 and the support body 8 are shown, and other components (such as the internal pin 4) are omitted. Fig.10 In the figure, the inner peripheral surface 221 of the gear body 22 is omitted.

[0143] First, as a premise, as mentioned above, the support body 8 is a component that supports the multiple inner pins 4. That is, the support body 8 bundles the multiple inner pins 4 to disperse the load acting on the multiple inner pins 4 when the rotation (rotation component) of the external gear 3 is transmitted to the inner ring 61. Specifically, there are multiple support holes 82 for inserting the multiple inner pins 4 respectively. In this basic structure, as an example, the diameter of the support hole 82 is equal to the diameter of the retaining hole 611 formed in the inner ring 61. Therefore, the support body 8 supports the multiple inner pins 4 in a state where each of the multiple inner pins 4 can rotate. That is, each of the multiple inner pins 4 is retained in a state where both the inner ring 61 and the support body 8 relative to the bearing member 6 can rotate.

[0144] In this way, the support body 8 positions the plurality of inner pins 4 relative to the support body 8 in both the circumferential and radial directions. That is, the inner pins 4 are inserted into the support holes 82 of the support body 8, so that the movement of the inner pins 4 in all directions within the plane orthogonal to the rotation axis Ax1 is restricted. Therefore, the inner pins 4 are positioned not only in the circumferential direction but also in the radial direction (radial direction) by the support body 8.

[0145] Here, the support body 8 has an annular shape in which at least the outer peripheral surface 81 is a perfect circle when viewed from above. And the support body 8 is positionally restricted by making the outer peripheral surface 81 contact the plurality of pins 23 in the internal gear 2. Since the plurality of pins 23 constitute the internal teeth 21 of the internal gear 2, in other words, the support body 8 is positionally restricted by making the outer peripheral surface 81 contact the internal teeth 21. Here, the diameter of the outer peripheral surface 81 of the support body 8 is the same as the diameter of the virtual circle (tooth tip circle) passing through the front end of the internal teeth 21 of the internal gear 2. Therefore, all of the plurality of pins 23 are in contact with the outer peripheral surface 81 of the support body 8. Thus, in a state where the support body 8 is positionally restricted by the plurality of pins 23, the center of the support body 8 is positionally restricted in a manner overlapping with the center (rotation axis Ax1) of the internal gear 2. Thus, the centering of the support body 8 is performed, and as a result, the centering of the plurality of inner pins 4 supported by the support body 8 is also performed by the plurality of pins 23.

[0146] In addition, the plurality of inner pins 4 rotate (revolve) around the rotation axis Ax1, thereby transmitting the rotation (autorotation component) of the external gear 3 to the inner ring 61. Therefore, the support body 8 supporting the plurality of inner pins 4 rotates around the rotation axis Ax1 together with the plurality of inner pins 4 and the inner ring 61. At this time, the support body 8 is centered using the plurality of pins 23, so the support body 8 rotates smoothly with the center of the support body 8 maintained on the rotation axis Ax1. Moreover, the support body 8 rotates in a state where its outer peripheral surface 81 is in contact with the plurality of pins 23, so that as the support body 8 rotates, the plurality of pins 23 each rotate (autorotate). Thus, the support body 8 and the internal gear 2 together form a needle bearing (needle roller bearing) and rotate smoothly.

[0147] That is, the outer peripheral surface 81 of the support body 8 rotates relatively with respect to the gear body 22 together with the plurality of inner pins 4 in a state of being in contact with the plurality of pins 23. Therefore, if the gear body 22 of the internal gear 2 is regarded as the "outer ring" and the support body 8 is regarded as the "inner ring", the plurality of pins 23 between the two function as "rolling elements (rollers)". In this way, the support body 8 and the internal gear 2 (gear body 22 and the plurality of pins 23) together constitute a needle bearing and can rotate smoothly.

[0148] Furthermore, since the support body 8 sandwiches the plurality of pins 23 between the gear bodies 22, the support body 8 also functions as a "stopper" that suppresses the movement of the pins 23 in the direction of separation from the inner peripheral surface 221 of the gear body 22. In other words, the plurality of pins 23 are sandwiched between the outer peripheral surface 81 of the support body 8 and the inner peripheral surface 221 of the gear body 22, thereby suppressing the floating of the plurality of pins 23 from the inner peripheral surface 221 of the gear body 22. In short, in this basic structure, the plurality of pins 23 are restricted from moving in the direction of separation from the gear body 22 by contacting the outer peripheral surface 81 of the support body 8.

[0149] However, if Fig. 9 As shown, in this basic structure, the support body 8 is located on the opposite side of the inner ring 61 of the bearing member 6 across the external gear 3. That is, the support body 8, the external gear 3 and the inner ring 61 are arranged in a row in a direction parallel to the rotation axis Ax1. In this basic structure, as an example, the support body 8 is located on the input side of the rotation axis Ax1 when viewed from the external gear 3, and the inner ring 61 is located on the output side of the rotation axis Ax1 when viewed from the external gear 3. In addition, the support body 8 supports both ends of the inner pin 4 in the longitudinal direction (direction parallel to the rotation axis Ax1) together with the inner ring 61, and the central part of the inner pin 4 in the longitudinal direction passes through the free fitting hole 32 inserted into the external gear 3. In short, the gear device 1 of this basic structure includes a bearing member 6, which has an outer ring 62 and an inner ring 61 arranged inside the outer ring 62, and the inner ring 61 is supported so as to be relatively rotatable relative to the outer ring 62. In addition, the gear body 22 is fixed to the outer ring 62. Here, the externally toothed gear 3 is located between the support body 8 and the inner ring 61 in the axial direction of the support body 8 .

[0150] According to this structure, the support body 8 and the inner ring 61 support both ends of the inner pin 4 in the longitudinal direction, so it is difficult for the inner pin 4 to tilt. In particular, it is also easy to withstand the bending force (bending moment load) acting on the plurality of inner pins 4 with respect to the rotation axis Ax1. In addition, in this basic structure, the support body 8 is sandwiched between the external gear 3 and the housing 10 in a direction parallel to the rotation axis Ax1. As a result, the support body 8 is directed toward the input side ( Fig. 9The movement of the inner pin 4 that penetrates the support hole 82 of the support body 8 and protrudes from the support body 8 toward the input side of the rotation axis Ax1 is restricted by the housing 10. Fig. 9 The movement of the left side) is also restricted by the shell 10.

[0151] In this basic structure, the support body 8 and the inner ring 61 are also in contact with both ends of the plurality of pins 23. Fig. 9 As shown, the support body 8 is in contact with one end (end on the input side of the rotation axis Ax1) of the pin 23 in the longitudinal direction (direction parallel to the rotation axis Ax1). The inner ring 61 is in contact with the other end (end on the output side of the rotation axis Ax1) of the pin 23 in the longitudinal direction (direction parallel to the rotation axis Ax1). According to this structure, the support body 8 and the inner ring 61 are centered at both ends in the longitudinal direction of the pin 23, so it is difficult for the inner pin 4 to tilt. In particular, it is easy to withstand the bending force (bending moment load) with respect to the rotation axis Ax1 acting on the plurality of inner pins 4.

[0152] In addition, the plurality of pins 23 have a length greater than the thickness of the support body 8. In other words, in the direction parallel to the rotation axis Ax1, the support body 8 is within the range of the tooth direction of the internal teeth 21. As a result, the outer peripheral surface 81 of the support body 8 contacts the plurality of pins 23 over the entire length of the tooth direction of the internal teeth 21 (direction parallel to the rotation axis Ax1). Therefore, it is difficult to cause an undesirable condition such as "single-side wear" in which the outer peripheral surface 81 of the support body 8 is partially worn.

[0153] In addition, in this basic structure, the outer peripheral surface 81 of the support body 8 has a smaller surface roughness than a surface of the support body 8 adjacent to the outer peripheral surface 81. In other words, the surface roughness of the outer peripheral surface 81 is smaller than the two end surfaces in the axial direction (thickness direction) of the support body 8. The "surface roughness" mentioned in the present invention refers to the roughness of the surface of an object. The smaller the value, the smaller (the fewer) the surface bumps are and the smoother the surface is. In this basic structure, as an example, the surface roughness is set to the arithmetic balance roughness (Ra). For example, through treatments such as grinding, the outer peripheral surface 81 is smaller than the surface roughness of the surface other than the outer peripheral surface 81 of the support body 8. In this structure, the rotation of the support body 8 becomes smoother.

[0154] In addition, in this basic structure, the hardness of the outer peripheral surface 81 of the support body 8 is lower than the peripheral surface of the plurality of pins 23 and higher than the inner peripheral surface 221 of the gear body 22. The "hardness" mentioned in the present invention refers to the hardness of an object, and the hardness of a metal is represented by the size of an indentation formed by pushing a steel ball with a certain pressure, for example. Specifically, as an example of the hardness of a metal, there are Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV) or Shore hardness (Hs), etc. As a means of increasing the hardness (hardening) of a metal part, there are, for example, alloying or heat treatment. In this basic structure, as an example, the hardness of the outer peripheral surface 81 of the support body 8 is increased by carburizing and quenching and other treatments. In this structure, even if the support body 8 rotates, it is difficult to generate wear powder, etc., and it is easy to maintain the smooth rotation of the support body 8 for a long time.

[0155] (4) Application examples

[0156] Next, application examples of the gear device 1 and the actuator 100 of the basic structure will be described.

[0157] The gear device 1 and the actuator 100 of the basic structure are suitable for use in a robot such as a horizontal multi-joint robot, that is, a so-called SCARA (Selective Compliance Assembly Robot Arm) type robot.

[0158] In addition, the gear device 1 and the actuator 100 of the basic structure are not limited to the horizontal multi-joint robot as described above, and can be, for example, an industrial robot other than the horizontal multi-joint robot or a robot other than the industry. Among industrial robots other than the horizontal multi-joint robot, for example, there are vertical multi-joint robots or parallel linkage robots. Among robots other than the industry, for example, there are household robots, nursing robots, or medical robots.

[0159] (Basic structure 2)

[0160] <Outline>

[0161] Regarding the gear device 1A of the basic structure, Figure 11 to Figure 13 As shown, the main external gear 3 and the structure for driving the external gear 3 are different from the gear device 1 of the basic structure 1. Hereinafter, the same reference numerals are attached to the same structures as the basic structure 1, and the description thereof is omitted as appropriate. Fig.11 1A is a schematic cross-sectional view of the gear device 1A. Fig.11 In FIG. 1 , enlarged views of regions Z1 and Z2 are shown with white frames. Fig.12 and Fig.13 yes Fig.11 A1-A1 line section view. Fig.12and Fig.13 In the example, the hatching is omitted even for the cross-section. Fig.12 and Fig.13 In the figure, the inner peripheral surface 221 of the gear body 22 is omitted.

[0162] The structure of the internal gear 2 itself is the same as that of the basic structure 1. In this basic structure, the internal gear 2 also has: an annular gear body 22; and a plurality of 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 state capable of self-rotation, and constitute the internal teeth 21. On the other hand, in this basic structure, the external gear 3 is an annular member having external teeth 31 and arranged on the inner side of the internal gear 2. In addition, the gear device 1A of this basic structure is greatly different from the basic structure 1 in that it includes a deflection generator 40, which is arranged on the inner side of the external gear 3 and causes the external gear 3 to bend. The deflection generator 40 has: a non-circular cam 41, which is driven to rotate around the rotation axis Ax1; and a bearing 42, which is mounted on the outer side of the cam 41. The gear device 1A deforms the external gear 3 as the cam 41 rotates, causing a portion of the external teeth 31 to mesh with a portion of the internal teeth 21 , thereby causing the external gear 3 to rotate relative to the rigid internal gear 2 by the same number of teeth as the internal gear 2 .

[0163] The "non-circular shape" mentioned in the present invention refers to a shape that is not a perfect circle, such as an elliptical shape and an oblong shape. In the present basic structure, as an example, the non-circular cam 41 of the deflection generator 40 is an "oblong shape". That is, in the present basic structure, the deflection generator 40 bends the external gear 3 into an oblong shape. The "oblong shape" mentioned in the present invention refers to a shape in which two semicircles are connected by two straight lines, the so-called track shape (elliptical shape). In more detail, a shape in which two semicircles with equal circumferential line radii are connected by two lines is referred to as an "oblong shape".

[0164] That is, in this basic structure, the gear body 22 of the internal gear 2 has rigidity, while the external gear 3 has flexibility. The "rigidity" mentioned in the present invention refers to the property of an object to resist deformation when an external force is applied to the object. In other words, an object with rigidity is difficult to deform even if an external force is applied. In addition, the "flexibility" mentioned in the present invention refers to the property of an object to undergo elastic deformation (bending) when an external force is applied to the object. In other words, an object with flexibility is prone to elastic deformation when an external force is applied. Therefore, "rigidity" and "flexibility" have opposite meanings.

[0165] In particular, in the present invention, the "rigidity" of the gear body 22 of the internal gear 2 and the "flexibility" of the external gear 3 are used in a relative sense. That is, the "rigidity" of the gear body 22 means that the gear body 22 has a relatively high rigidity at least compared to the external gear 3, that is, it is difficult to deform even if an external force is applied to the gear body 22. Similarly, the "flexibility" of the external gear 3 means that the external gear 3 has a relatively high flexibility at least compared to the gear body 22, that is, it is easy to elastically deform when an external force is applied to the external gear 3.

[0166] Furthermore, in the gear device 1A of this basic structure, the external gear 3 is bent into a non-circular shape (an elongated circular shape as an example) by the deflection generator 40, so that the external teeth 31 of the external gear 3 are partially meshed with the internal teeth 21 (pin 23) of the internal gear 2. In this state, when the cam 41 of the deflection generator 40 rotates, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, and relative rotation is generated between the two gears (the internal gear 2 and the external gear 3) according to the difference in the number of teeth between the external gear 3 and the internal gear 2. In short, the external gear 3 does not perform an eccentric motion (swing) rotating around an eccentric axis deviated from the rotation axis Ax1 as the center as in the basic structure 1, but is deformed into a non-circular shape (an elongated circular shape as an example) by the deflection generator 40 in the major axis direction D1 (refer to Fig.12 ) rotates around the rotation axis Ax1, 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. Here, if the gear body 22 of the internal gear 2 is fixed, the external gear 3 rotates with the relative rotation of the two gears. As a result, the external gear 3 obtains a rotation output that is reduced by a relatively high reduction ratio corresponding to the difference in the number of teeth of the two gears.

[0167] Here, if Fig.13As shown, in the gear device 1A of this basic structure, the internal teeth 21 and the external teeth 31 mesh with each other within the simultaneous meshing range Ra1 occupying more than 180 degrees in the circumferential direction of the internal gear 2. The "simultaneous meshing range" mentioned in the present invention refers to the range in which the internal teeth 21 and the external teeth 31 mesh with each other at any time, and the entire area of ​​the simultaneous meshing range is the meshing position of the internal teeth 21 and the external teeth 31. That is, in the gear device 1A, the external teeth 31 of the external gear 3 and the internal teeth 21 (pin 23) of the internal gear 2 are partially meshed, and the internal teeth 21 and the external teeth 31 mesh only in the simultaneous meshing range Ra1 in the circumferential direction of the internal gear 2, and the internal teeth 21 and the external teeth 31 do not mesh with each other outside the simultaneous meshing range Ra1. In addition, the meshing position of the internal teeth 21 and the external teeth 31, that is, the simultaneous meshing range Ra1, moves the circumferential direction of the internal gear 2 with the rotation of the cam 41. In this basic structure, such a simultaneous meshing range Ra1 occupies more than 180 degrees, that is, more than half, of the circumference of the internal gear 2. In other words, the non-meshing range Ra2 where the internal teeth 21 and the external teeth 31 do not mesh is less than 180 degrees, that is, less than half, of the circumference of the internal gear 2.

[0168] In summary, in the gear device 1A of this basic structure, the external gear 3 is constrained by the internal gear 2 within the simultaneous meshing range Ra1 of more than half of the circumference of the internal gear 2, thereby suppressing the movement (deformation) of the external gear 3 in the direction away from the flexure generator 40. Therefore, the meshing of the internal teeth 21 and the external teeth 31 can be stabilized over a large range of more than half of the circumference of the internal gear 2. As a result, the gear device 1A is less likely to cause vibrations during operation, and tooth skipping caused by the instantaneous deviation of the meshing between the internal gear 2 and the external gear 3 when excessive torque is applied during operation. In other words, the gear device 1A according to this basic structure has the advantage of a structure that can achieve low vibration and improved impact resistance.

[0169] In addition, in this basic structure, as described above, the external gear 3 does not perform an eccentric motion (oscillation) of rotating around the eccentric shaft deviated from the rotation axis Ax1, but rotates around the rotation axis Ax1 in the major axis direction D1 deformed into a non-circular shape by the deflection generator 40. Therefore, in the gear device 1A of this basic structure, the eccentric shaft 7 for causing the external gear 3 to perform an eccentric motion is omitted, and the cam 41 of the deflection generator 40 is provided as an input mechanism instead of the eccentric shaft 7.

[0170] Furthermore, the external gear 3 rotates (rotates) only around the rotation axis Ax1 (on the output side), and does not generate a swing component (revolution component) of the external gear 3, so the rotation (rotation component) of the external gear 3 can be directly taken out from the external gear 3 without using a plurality of inner pins 4. Therefore, in the gear device 1A of this basic structure, the plurality of inner pins 4 and the support body 8 supporting the plurality of inner pins 4 are also omitted. Of course, in the external gear 3, the plurality of inner pin holes 32 for inserting the plurality of inner pins 4 are also omitted.

[0171] <Structure details>

[0172] For detailed results of the gear device 1A of this basic structure, refer to Figure 11 to Figure 13 Provide explanation.

[0173] As described above, the gear device 1A of this basic structure includes the internal gear 2, the external gear 3 and the deflection generator 40. In this basic structure, the internal gear 2, the external gear 3 and the deflection generator 40, which are the structural elements of the gear device 1A, are made of metals such as stainless steel, cast iron, carbon steel for mechanical structure, chrome-molybdenum steel, phosphor bronze or aluminum bronze. The metal mentioned here includes metals subjected to surface treatment such as nitriding treatment.

[0174] In the gear device 1A of the basic structure, the cylindrical external gear 3 is used. The deflection generator 40 is combined with the cylindrical external gear 3 so as to be accommodated in the cylindrical external gear 3 .

[0175] In addition, in this basic structure, as an example, the gear device 1A includes a first bracket 18 (see Fig.11 ) and the second bracket 19 (refer to Fig.11 ). The first bracket 18 is fixed to the gear body 22 of the internal gear 2, and the second bracket 19 is fixed to the external gear 3. Furthermore, the first bracket 18 is fixed to the inner ring 61 of the bearing member 6, and the second bracket 19 is fixed to the outer ring 62 of the bearing member 6. In this basic structure, the first bracket 18 is integrated with the inner ring 61, and the second bracket 19 is integrated with the outer ring 62. As a result, along with the relative rotation of the internal gear 2 and the external gear 3, the second bracket 19 (and the outer ring 62) as a movable member rotates relative to the first bracket 18 (and the inner ring 61) as a fixed member. A mounting hole 181 for mounting the object member is formed in the first bracket 18, and a mounting hole 191 for mounting the object member is formed in the second bracket 19.

[0176] Furthermore, in this basic structure, when the gear device 1A is used for the actuator 100, a rotational force as an input is applied to the flexure generator 40, and a rotational force as an output is taken out from the second bracket 19 fixed to the external gear 3. That is, the gear device 1A operates with the rotation of the flexure generator 40 as the input rotation and the rotation of the external gear 3 (second bracket 19) as the output rotation. As a result, in the gear device 1A, an output rotation that is reduced by a relatively high reduction ratio relative to the input rotation can be obtained.

[0177] Furthermore, in the gear device 1A of this basic structure, the rotation axis Ax1 on the input side and the rotation axis Ax1 on the output side are on the same straight line. In other words, the rotation axis Ax1 of the flexure generator 40 on the input side and the rotation axis Ax1 of the external gear 3 on the output side are coaxial. Here, the rotation axis Ax1 on the input side is the rotation center of the flexure generator 40 to which the input rotation is given, and the rotation axis Ax1 on the output side is the rotation center of the external gear 3 that generates the output rotation. That is, in the gear device 1A, it is possible to obtain an output rotation that is reduced at a relatively high reduction ratio on the same axis with respect to the input rotation.

[0178] Similar to the basic structure 1, the internal gear 2 has an annular (circular) gear body 22 and a plurality of pins 23. As described above, the gear body 22 of the internal gear 2 is fixed to the first bracket 18 (and the inner ring 61). Therefore, a plurality of fixing holes 222 for fixing are formed in the gear body 22 (see Fig.12 ).

[0179] The external gear 3 is a flexible annular component having external teeth 31. In this basic structure, the external gear 3 is a component formed into a cylindrical shape using a relatively thin-walled metal elastic body (metal plate). That is, the external gear 3 is flexible due to its relatively small (thin) thickness. The external gear 3 has a cylindrical main body 34 and a flange 35. In a state where the external gear 3 does not produce elastic deformation, at least the inner circumferential surface 301 of the main body 34 has a cylindrical shape that is a perfect circle when viewed from above. The central axis of the main body 34 coincides with the rotation axis Ax1. The flange 35 is continuous with the open end on one side of the main body 34 and extends from the main body 34 toward the radial outside, thereby having an annular shape that is a perfect circle when viewed from above.

[0180] As described above, the external gear 3 is fixed to the second bracket 19 (and the outer ring 62). Therefore, a plurality of fixing holes 351 for fixing are formed in the flange portion 35 of the external gear 3 (see Fig.11). The periphery of the fixing hole 351 in the flange portion 35 is thicker than the other parts of the flange portion 35. Furthermore, in the main body portion 34, an opening surface 36 is formed on the end surface on the opposite side of the flange portion 35 in the direction of the rotation axis Ax1. In this basic structure, the main body portion 34 and the flange portion 35 are integrally formed by a metal member, thereby realizing a seamless external gear 3.

[0181] Here, the flexure generator 40 is combined with the external gear 3 in such a manner that the non-circular (elliptical) flexure generator 40 is embedded inside the main body 34. As a result, the external gear 3 receives an external force in the radial direction (a direction orthogonal to the rotation axis Ax1) from the inside to the outside from the flexure generator 40, thereby elastically deforming into a non-circular shape. In this basic structure, by combining the flexure generator 40 with the external gear 3, the main body 34 of the external gear 3 is elastically deformed into an elongated shape. That is, the state in which the external gear 3 is elastically deformed refers to the state in which the flexure generator 40 is not combined with the external gear 3. On the contrary, the state in which the external gear 3 is elastically deformed refers to the state in which the flexure generator 40 is combined with the external gear 3.

[0182] More specifically, the deflection generator 40 is embedded in the end of the main body 34 of the external gear 3 on the side of the opening surface 36 in the direction of the rotation axis Ax1. Therefore, when the external gear 3 is elastically deformed, the end of the external gear 3 on the side of the opening surface 36 in the direction of the rotation axis Ax1 is deformed more than the end of the flange 35, and becomes a shape closer to an oblong shape. Due to the difference in the amount of deformation in the direction of the rotation axis Ax1, when the external gear 3 is elastically deformed, the inner peripheral surface of the main body 34 of the external gear 3 includes a tapered surface inclined with respect to the rotation axis Ax1.

[0183] In addition, the external teeth 31 are formed along the circumferential direction of the main body 34 at the end portion on the side opposite to the flange portion 35 (the input side of the rotation axis Ax1) of the outer peripheral surface of the main body 34. In other words, the external teeth 31 are provided at the end portion on the side of the opening surface 36 in the direction of the rotation axis Ax1 of the main body 34 of the external gear 3. All of the plurality of teeth constituting the external teeth 31 have the same shape and are provided at equal intervals over the entire area in the circumferential direction of the outer peripheral surface of the main body 34. In other words, the pitch circle of the external teeth 31 is a perfect circle in a plan view when the external gear 3 is not elastically deformed. The external teeth 31 are formed only within a certain width from the end edge on the side of the opening surface 36 of the main body 34. Specifically, the external teeth 31 are formed on the outer peripheral surface of the main body 34 at least in the portion (the end portion on the side of the opening surface 36) where the deflection generator 40 (bearing 42 thereof) is embedded in the direction of the rotation axis Ax1. The tooth directions of the external teeth 31 are all parallel to the rotation axis Ax1.

[0184] In summary, in the gear device 1A of the present and basic structure, the tooth direction of the internal teeth 21 of the internal gear 2 and the external teeth 31 of the external gear 3 are parallel to the rotation axis Ax1. Therefore, in the present basic structure, the "tooth direction" is a direction parallel to the rotation axis Ax1. In addition, the dimension of the tooth direction of the internal teeth 21 is the tooth width of the internal teeth 21, and similarly, the dimension of the tooth direction of the external teeth 31 is the tooth width of the external teeth 31, so the tooth direction is synonymous with the tooth width direction.

[0185] The external gear 3 thus constructed is arranged on the inner side of the internal gear 2. Here, the external gear 3 is combined with the internal gear 2 in such a manner that only the end portion of the outer peripheral surface of the main body 34 on the side opposite to the flange portion 35 is inserted into the inner side of the internal gear 2. That is, the portion of the main body 34 of the external gear 3 into which the deflection generator 40 is embedded in the direction of the rotation axis Ax1 (the end portion on the side of the opening surface 36) is inserted into the inner side of the internal gear 2. Here, the external teeth 31 are formed on the outer peripheral surface of the external gear 3, and the internal teeth 21 (a plurality of pins 23) are formed on the inner peripheral surface of the internal gear 2. Therefore, in a state where the external gear 3 is arranged on the inner side of the internal gear 2, the external teeth 31 and the internal teeth 21 are opposite to each other.

[0186] Here, the number of teeth of the internal teeth 21 of the internal gear 2 is 2N (N is a positive integer) greater than the number of teeth of the external teeth 31 of the external gear 3. In this basic structure, as an example, N is "1", so that the number of teeth (58) of the external gear 3 (external teeth 31) is "2" less than the number of teeth (60) of the internal gear 2 (internal teeth 21). Such a difference in the number of teeth between the external gear 3 and the internal gear 2 defines the reduction ratio of the output rotation to the input rotation in the gear device 1A.

[0187] Here, in this basic structure, as an example, the dimension (tooth width) of the external teeth 31 in the tooth direction is smaller than the dimension (tooth width) of the internal teeth 21 (pin 23) in the tooth direction. Therefore, in the direction parallel to the rotation axis Ax1, the external teeth 31 are within the range of the tooth direction of the internal teeth 21. In other words, the internal teeth 21 protrude to at least one side in the tooth direction relative to the external teeth 31. In this basic structure, the internal teeth 21 protrude to both sides in the tooth direction relative to the external teeth 31.

[0188] Here, in a state where the external gear 3 is not elastically deformed (in a state where the external gear 3 is not combined with the deflection generator 40), the pitch circle of the external teeth 31 describing a perfect circle is set to be one circle smaller than the pitch circle of the internal teeth 21 also describing a perfect circle. That is, in a state where the external gear 3 is not elastically deformed, the external teeth 31 and the internal teeth 21 face each other with a gap therebetween, and are not meshed with each other.

[0189] On the other hand, when the external gear 3 is elastically deformed (the deflection generator 40 is combined with the external gear 3), the main body 34 is deflected into an oblong shape (non-circular shape), so that the external teeth 31 of the external gear 3 and the internal teeth 21 of the internal gear 2 are partially meshed. Fig.12 As shown, the main body 34 of the external gear 3 (at least the end portion on the opening surface 36 side) is elastically deformed into an oval shape, whereby the external teeth 31 located at both ends of the long axis direction D1 of the oval shape mesh with the internal teeth 21. In contrast, the external teeth 31 located at both ends of the short axis direction D2 of the oval shape do not mesh with the internal teeth 21.

[0190] In other words, the major diameter of the pitch circle of the oblong external teeth 31 is consistent with the diameter of the pitch circle of the internal teeth 21 described as a perfect circle, and the minor diameter of the pitch circle of the oblong external teeth 31 is smaller than the diameter of the pitch circle of the internal teeth 21 described as a perfect circle. In this way, when the external gear 3 is elastically deformed, part of the teeth constituting the external teeth 31 mesh with part of the teeth constituting the internal teeth 21 (pins 23). As a result, in the gear device 1A, part of the external teeth 31 can be meshed with part of the internal teeth 21.

[0191] The deflection generator 40 is a member that causes the external gear 3 to bend, thereby causing the external teeth 31 of the external gear 3 to generate wave motion. In this basic structure, the deflection generator 40 is a member whose outer peripheral shape is non-circular, specifically, an oval shape, when viewed from above.

[0192] The deflection generator 40 has a non-circular (here, an oblong) cam 41 and a bearing 42 mounted on the outer periphery of the cam 41. That is, the cam 41 and the bearing 42 are combined in such a way that the circular (oblong) cam 41 is not embedded inside the inner ring 422 of the bearing 42. As a result, the bearing 42 receives an external force in a radial direction (a direction orthogonal to the rotation axis Ax1) from the inside of the inner ring 422 toward the outside from the cam 41, thereby elastically deforming into a non-circular shape. In other words, the state in which the bearing 42 is not elastically deformed refers to the state in which the cam 41 is not combined with the bearing 42. On the contrary, the state in which the bearing 42 is elastically deformed refers to the state in which the cam 41 and the bearing 42 are combined.

[0193] The cam 41 is a non-circular (here, an oblong) member that is driven to rotate about the rotation axis Ax1 on the input side. The cam 41 has a cylindrical portion 411 (see Fig.11 ) and the non-circular portion 412 (refer to Fig.11), at least the outer peripheral surface of the non-circular portion 412 is non-circular when viewed from above. The non-circular portion 412 has a predetermined thickness in the direction of the rotation axis Ax1. Thus, the non-circular portion 412 has the same degree of rigidity as the internal gear 2. However, the thickness of the non-circular portion 412 is smaller (thinner) than the thickness of the internal gear 2. As described above, in this basic structure, the rotation of the flexure generator 40 is used as the input rotation. Therefore, the drive source 101 of the actuator 100 is installed in the flexure generator 40. A cam hole 413 for mounting the drive source 101 is formed in the cylindrical portion 411 of the cam 41 of the flexure generator 40.

[0194] The bearing 42 includes an outer ring 421, an inner ring 422, and a plurality of rolling elements 423. In this basic structure, the bearing 42 is formed of a deep groove ball bearing using spherical balls as the rolling elements 423, as an example.

[0195] The outer ring 421 and the inner ring 422 are both annular components. The outer ring 421 and the inner ring 422 are both annular components formed using a metal elastic body (metal plate) with a relatively thin wall. That is, the outer ring 421 and the inner ring 422 are both flexible due to their relatively small (thin) thickness. In this basic structure, the outer ring 421 and the inner ring 422 have a circular ring shape that is a perfect circle when viewed from above when the bearing 42 is not elastically deformed (the cam 41 is not combined with the bearing 42). The inner ring 422 is one circle smaller than the outer ring 421 and is arranged on the inner side of the outer ring 421. Here, the inner diameter of the outer ring 421 is larger than the outer diameter of the inner ring 422, so a gap is generated between the inner peripheral surface 425 of the outer ring 421 and the outer peripheral surface of the inner ring 422.

[0196] The plurality of rolling elements 423 are arranged in the gap between the outer ring 421 and the inner ring 422. The plurality of rolling elements 423 are arranged in a row along the circumferential direction of the outer ring 421. The plurality of rolling elements 423 are metal balls (balls) of the same shape and are arranged at equal intervals over the entire circumferential area of ​​the outer ring 421. The bearing 42 also has a retainer 424, and the plurality of rolling elements 423 are retained between the outer ring 421 and the inner ring 422 by the retainer 424.

[0197] By means of the structure of the bearing 42, the cam 41 and the bearing 42 are combined, whereby the inner ring 422 of the bearing 42 is fixed to the cam 41, and the inner ring 422 is elastically deformed into an oblong shape similar to the outer peripheral shape of the non-circular portion 412 of the cam 41. At this time, the outer ring 421 of the bearing 42 is pressed by the inner ring 422 via the plurality of rolling elements 423 and elastically deformed into an oblong shape. Thus, both the outer ring 421 and the inner ring 422 of the bearing 42 are elastically deformed into an oblong shape. In this way, in the state where the bearing 42 is elastically deformed (the state where the cam 41 and the bearing 42 are combined), the outer ring 421 and the inner ring 422 become oblong shapes similar to each other.

[0198] Even when the bearing 42 is elastically deformed, the gap between the outer ring 421 and the inner ring 422 is maintained substantially constant over the entire circumference of the outer ring 421 because the plurality of rolling elements 423 are interposed between the outer ring 421 and the inner ring 422. In this state, the outer ring 421 can rotate relative to the inner ring 422 by the rolling of the plurality of rolling elements 423 between the outer ring 421 and the inner ring 422. Thus, when the cam 41 rotates about the rotation axis Ax1 in the state in which the bearing 42 is elastically deformed, the rotation of the cam 41 is not transmitted to the outer ring 421, but the elastic deformation of the inner ring 422 is transmitted to the outer ring 421 via the plurality of rolling elements 423. That is, in the deflection generator 40, when the cam 41 rotates about the rotation axis Ax1, the outer ring 421 is elastically deformed so that the long circular shape that is followed by the outer ring 421 rotates about the rotation axis Ax1. Therefore, as a whole, the outer peripheral shape of the deflection generator 40, which is called an oval shape when viewed from one side of the rotation axis Ax1, changes with the rotation of the cam 41 so that its major axis (major axis direction D1) rotates around the rotation axis Ax1.

[0199] The deflection generator 40 thus constructed is arranged on the inner side of the external gear 3. Here, the external gear 3 is combined with the deflection generator 40 in such a manner that only the end portion of the main body 34 on the side opposite to the flange portion 35 (the side of the opening surface 36) is engaged with the deflection generator 40. At this time, the bearing 42 of the deflection generator 40 is arranged between the outer peripheral surface of the non-circular portion 412 of the cam 41 and the inner peripheral surface of the main body 34 of the external gear 3. Here, the outer diameter of the outer ring 421 in the state where the bearing 42 is not elastically deformed (the state where the cam 41 is not combined with the bearing 42) is the same as the inner diameter of the external gear 3 (main body 34) in the state where the elastic deformation is not generated. Therefore, the outer peripheral surface of the outer ring 421 in the deflection generator 40 is in contact with the inner peripheral surface of the external gear 3 over the entire circumference of the bearing 42 in the circumferential direction. Thus, when the external gear 3 is elastically deformed (the deflection generator 40 and the external gear 3 are combined), the body 34 is deflected into an oval shape (non-circular shape). In this state, the external gear 3 is fixed to the outer ring 421 of the bearing 42.

[0200] However, since only the external gear 3 and the flexure generator 40 are engaged, the external gear 3 and the outer ring 421 of the bearing 42 are not completely fixed. Therefore, a gap, although small, is generated between the external gear 3 and the outer ring 421 embedded inside the external gear 3. Strictly speaking, the diameter of the outer peripheral surface of the outer ring 421 is slightly smaller than the diameter of the inner peripheral surface of the external gear 3, so the gap between the outer ring 421 and the external gear 3 is not completely filled, and a gap is generated at least partially.

[0201] The "gap" mentioned in the present invention refers to the space that may be generated between the opposing surfaces of two objects, and a gap may be generated between the two objects even if the two objects are not separated. In other words, even if the two objects are in contact, a gap may be generated between the two objects, although it is small. A gap is generated between the outer peripheral surface of the outer ring 421 and the inner peripheral surface of the outer gear 3, which are opposite to each other. However, basically, the outer peripheral surface of the outer ring 421 is in contact with the inner peripheral surface of the outer gear 3, so no large gap is generated between the two. Therefore, the gap between the outer ring 421 and the external gear 3 is a small gap that can be locally generated between the outer peripheral surface of the outer ring 421 and the inner peripheral surface of the external gear 3. As an example, a microscopic gap of a degree that the lubricant can penetrate is generated between the outer peripheral surface of the outer ring 421 and the inner peripheral surface of the external gear 3.

[0202] like Fig.12 As shown, in the gear device 1A having the above structure, the external gear 3 is bent into an elongated shape (non-circular shape), so that the external teeth 31 of the external gear 3 and the internal teeth 21 of the internal gear 2 are partially meshed. That is, by elastically deforming the external gear 3 (the main body 34) into an elongated shape, the external teeth 31 and the internal teeth 21 at two locations corresponding to the two ends of the long axis direction D1 of the elongated shape are meshed. And when the cam 41 rotates around the rotation axis Ax1, the rotation of the cam 41 is not transmitted to the outer ring 421 and the external gear 3, and the elastic deformation of the inner ring 422 is transmitted to the outer ring 421 and the external gear 3 via the plurality of rolling elements 423. Therefore, the outer peripheral shape of the external gear 3 in an elongated shape viewed from one side of the rotation axis Ax1 changes with the rotation of the cam 41 in such a manner that its major axis (the major axis direction D1) rotates around the rotation axis Ax1.

[0203] As a result, an undulating motion is generated in the external teeth 31 formed on the outer peripheral surface of the external gear 3. By generating the undulating motion of the external teeth 31, the meshing position of the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, thereby generating relative rotation between the external gear 3 and the internal gear 2. That is, since the external teeth 31 mesh with the internal teeth 21 at both ends of the long circular shape formed by the external gear 3 (the main body 34) in the major axis direction D1, the meshing position of the internal teeth 21 and the external teeth 31 is moved by rotating around the rotation axis Ax1 through the major axis of the long circular shape. In this way, for the gear device 1A of this basic structure, the external gear 3 is deformed along with the rotation of the flexure generator 40 centered on the rotation axis Ax1, so that a part of the external teeth 31 meshes with a part of the internal teeth 21, and the external gear 3 rotates according to the difference in the number of teeth with the internal gear 2.

[0204] However, as described above, in the gear device 1A, the difference in the number of teeth between the external gear 3 and the internal gear 2 defines the reduction ratio of the output rotation relative to the input rotation in the gear device 1A. That is, when the number of teeth of the rigid internal gear 2 is set to "V1" and the number of teeth of the external gear 3 is set to "V2", the reduction ratio R1 is expressed by the following formula 1.

[0205] R1=V2 / (V1-V2)……(Formula 1)

[0206] In short, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the external gear 3 is, the greater the reduction ratio R1 is. For example, if the number of teeth V1 of the internal gear 2 is "60" and the number of teeth V2 of the external gear 3 is "58", and the difference in the number of teeth (V1-V2) is "2", then according to the above formula 1, the reduction ratio R1 is "29". In this case, when the cam 41 rotates clockwise around the rotation axis Ax1 for one rotation (360 degrees), the external gear 3 rotates counterclockwise around the rotation axis Ax1 by only the difference in the number of teeth "2" (that is, 12.9 degrees).

[0207] According to the gear device 1A of this basic structure, such a high reduction ratio R1 can be achieved by the combination of the primary gears (the internal gear 2 and the external gear 3).

[0208] However, as described above, the gear device 1A of the basic structure is configured such that the meshing range Ra1 of the internal teeth 21 and the external teeth 31 is greater than 180 degrees in the circumferential direction of the internal gear 2. Fig.13 As shown, the meshing range Ra1 occupies more than 180 degrees of the circumference of the internal gear 2, that is, more than half. On the other hand, the non-meshing range Ra2 where the internal teeth 21 and the external teeth 31 do not mesh is suppressed to less than 180 degrees of the circumference of the internal gear 2, that is, less than half.

[0209] More specifically, the simultaneous meshing range Ra1 occupies more than 180 degrees and less than 300 degrees in the circumferential direction of the internal gear 2. That is, the non-meshing range Ra2 occupies more than 60 degrees and less than 180 degrees in the circumferential direction of the internal gear 2. The upper limit of the range occupied by the simultaneous meshing range Ra1 in the circumferential direction of the internal gear 2 is not limited to 300 degrees, and may be greater than 300 degrees, and may also be 190 degrees, 200 degrees, 220 degrees, 240 degrees, 260 degrees, or 280 degrees, etc.

[0210] In addition, in this basic structure, the meshing range Ra1 is divided into two locations in the circumferential direction of the internal gear 2. Fig.13As shown, the internal teeth 21 mesh with the external teeth 31 in the simultaneous meshing range Ra1 provided at two locations in the circumferential direction of the internal gear 2. Therefore, the non-meshing range Ra2 is also provided at two locations in the circumferential direction of the internal gear 2 in the same manner.

[0211] Furthermore, in this basic structure, the cam 41 has an oblong shape formed by connecting two semicircles by two straight lines. Therefore, in the external gear 3 that is elastically deformed by the cam 41, (at least the end portion on the side of the opening surface 36) is also an oblong shape. Therefore, the external teeth 31 located at both ends of the long axis direction D1 of the oblong shape mesh with the internal teeth 21, and the internal and external teeth 31 mesh with the internal teeth 21 in the simultaneous meshing range Ra1 of two locations in the circumferential direction of the internal gear 2.

[0212] Furthermore, the simultaneous meshing range Ra1 occupies more than 180 degrees in the circumferential direction of the internal gear 2, so not only the external teeth 31 located at both ends of the long circular shape in the major axis direction D1, but also a part of the external teeth 31 located on the side of the short axis direction D2 of the long circular shape meshes with the internal teeth 21. In short, when the internal gear 2 is equally divided into four areas in the circumferential direction, which are centered on the long axis direction D1 and the short axis direction D2 of the long circular shape, at least a part of the two areas located on both sides of the short axis direction D2 also serve as the simultaneous meshing range Ra1, so that the external teeth 31 mesh with the internal teeth 21.

[0213] Thus, within the simultaneous meshing range Ra1 of more than half of the circumference of the internal gear 2, the external gear 3 is constrained by the internal gear 2, thereby suppressing the movement (deformation) of the external gear 3 in the direction away from the flexure generator 40. That is, at least a portion of the external teeth 31 located on the side of the minor axis direction D2 of the oblong shape is constrained by the internal gear 2, thereby limiting the movement in the direction away from the flexure generator 40. As a result, the meshing of the internal teeth 21 and the external teeth 31 can be stabilized over a wide range of more than half of the circumference of the internal gear 2, and the gear device 1A is less likely to produce vibrations during operation, and tooth skipping caused by the instantaneous deviation of the meshing between the internal gear 2 and the external gear 3 when excessive torque is applied during operation.

[0214] In this basic structure, as an example, in the circumferential direction of the internal gear 2, the range of 150 degrees on both sides of the long-axis direction D1 of the long circle shape and centered on the long-axis direction D1 is the simultaneous meshing range Ra1. Therefore, from the perspective of the entire circumferential direction of the internal gear 2, the range of 300 degrees is the simultaneous meshing range Ra1. On the other hand, in the circumferential direction of the internal gear 2, the range of 30 degrees on both sides of the short-axis direction D2 of the long circle shape and centered on the short-axis direction D2 is the non-meshing range Ra2. Therefore, from the perspective of the entire circumferential direction of the internal gear 2, the range of 60 degrees is the non-meshing range Ra2.

[0215] As described above, in order to make the range of more than 180 degrees in the circumferential direction of the internal gear 2 the simultaneous meshing range Ra1, it is necessary to suppress the deformation of the external gear 3 to be relatively small, and suppress the pitch circle of the internal teeth 21 of the internal gear 2 as a perfect circle and the pitch circle of the external teeth 31 of the external gear 3 as an oblong shape to be small. Therefore, as the tooth profile of the external teeth 31 in the external gear 3, a tooth profile that achieves meshing that satisfies the meshing conditions of the gear that transmits rotation at an equal speed ratio in mechanics can be adopted, rather than meshing based on an approximate tooth profile. Specifically, the external teeth 31 have a trochoid tooth profile. The difference in the number of teeth of the external teeth 31 relative to the internal teeth 21 is a 2-piece difference.

[0216] That is, the gear device 1A of this basic structure is not a "harmonic gear device" that meshes with the internal gear 2 by elastic deformation of the external gear 3, but is based on an inscribed planetary gear device that achieves meshing of a large number of teeth of the internal gear 2 and the external gear 3 at the same time even without elastic deformation, and ensures that the mechanics of the gear meshing conditions are mostly satisfied. As a result, in the gear device 1A, it is possible to achieve load dispersion, and the deformation amount of the external gear 3 is suppressed to be small, and stress concentration on the external gear 3 is not likely to occur. As a result, damage to the external gear 3 during elastic deformation is less likely to occur, and the durability of the gear device 1A is improved.

[0217] <Tooth profile design of external gear>

[0218] The tooth profile design of the external gear 3 used in the gear device 1A of the basic structure is shown in FIG. Figures 14A to 23 Provide explanation. Figures 14A to 23 This is a conceptual diagram for explaining the procedure of designing the tooth profile of the external gear 3 , and does not illustrate the structure (including the number of teeth, etc.) of the gear device 1A of this basic structure.

[0219] First, if Fig.14A As shown, a pitch S1 corresponding to the internal gear 2 and a pitch S2 corresponding to the external gear 3 are set. The center of the pitch S2 is eccentric with respect to the center of the pitch S1 by an eccentricity e1. The inner diameter d1 of the pitch S1 is the diameter of the pitch circle of the internal gear 2 at the meshing position, and is expressed by the following formula 2 using a positive integer "n".

[0220] d1=(n+1)×e1×2··· (Formula 2)

[0221] On the other hand, the outer diameter d2 of the pitch S2 is the diameter of the pitch circle of the external gear 3 at the meshing position, and is expressed by the following Formula 3 using a positive integer “n”.

[0222] d2=n×e1×2··· (Formula 3)

[0223] Furthermore, in the displacement direction from the center of the node S1 toward the node S2 (at Fig.14AThe virtual pin V0 is set at a position of a distance L0 corresponding to the pin 23 constituting the internal tooth 21. The relative position of the virtual pin V0 with respect to the segment S1 is fixed, and as described later, when the segment S1 revolves (rotates), the virtual pin V0 revolves (rotates) together with the segment S1. The diameter dp1 of the virtual pin V0 is the diameter of the pin 23. The virtual pin V0 creates a tooth profile (of the external tooth 31) on the segment S2 that becomes the meshing object of the segment S1 (internal tooth 21).

[0224] Here, as an example, the integer n is assumed to be "49", and the eccentricity e1 is assumed to be "0.7". In this case, the inner diameter d1 of the node S1 is "70", and the outer diameter d2 of the node S2 is "68.6". Furthermore, the distance L0 from the center of the node S1 to the center of the virtual pin V0 is assumed to be "42.3".

[0225] Specifically, if Fig. 14B As shown in FIG. 1 , when the segment S1 revolves n times (49 times in this basic structure) on the segment S2 without sliding, the virtual pin V0 located at a fixed position relative to the segment S1 revolves n times around the segment S2. At this time, the orbit of the center of the virtual pin V0 forms a cycloid curve, and the envelope formed by the virtual pin V0 on the cycloid curve becomes the tooth profile of the external tooth 31. Thus, n (49) tooth profiles are formed, and n tooth tops and n tooth roots are formed.

[0226] In addition, if Fig.15A As shown in FIG. 1 , it is assumed that the number of virtual pins V0 attached to the node S1 is set to "n+1" (50 in the present basic structure), and these "n+1" virtual pins V0 are arranged at equal intervals in the circumferential direction of the node S1. In this case, the orbit of the center of the plurality of ("n+1") virtual pins V0 located at a fixed position relative to the node S1 forms a cycloid curve, as shown in FIG. Fig. 15B As shown in FIG. 1 , the envelope formed by the virtual pin V0 on the cycloid curve becomes the tooth profile of the external tooth 31. Thus, through one revolution of the node S1, Fig. 14B Similarly, n (49) tooth shapes are formed.

[0227] Here, in Fig. 15B In the example, the common normal lines of all the contact points of the meshing between the external teeth 31 of the external gear 3 and the internal teeth 21 (a plurality of pins 23) pass through the fixed point (node ​​Pp1), satisfying the mechanical meshing conditions of the gears. Fig. 15BAs indicated by the dotted lines (two-dot chain lines), the extension direction of these common normals coincides with the direction of the load acting on the internal gear 2 from the external gear 3. Furthermore, when the first quadrant Q1, the second quadrant Q2, the third quadrant Q3, and the fourth quadrant Q4 are set in the circumferential direction of the node S1, it can be seen from the direction of the load that the meshing that generates the effective load is in the first quadrant Q1 and the fourth quadrant Q4. On the other hand, in the second quadrant Q2 and the third quadrant Q3, it can be seen from the direction of the load that there is almost no meshing that generates the effective load. Therefore, the meshing of the external teeth 31 and the internal teeth 21 in the second quadrant Q2 and the third quadrant Q3, where no effective meshing is generated, is eliminated, and other external teeth 31 with a phase deviation of 180 degrees are arranged in the second quadrant Q2 and the third quadrant Q3.

[0228] That is, Fig.16A and Fig. 16B As shown, in the same inscribed planetary gear device as that shown in basic structure 1, two external gears 3 whose eccentric directions differ by 180 degrees are assumed. Fig.16A The external gear 3A is shown as being eccentric to the right by an eccentricity e1 relative to the center of the internal gear 2. Fig. 16B The external gear 3B is shown to be eccentric to the left by an eccentricity e1 with respect to the center of the internal gear 2 .

[0229] Furthermore, the two external gears 3A and 3B, which are 180 degrees out of phase with each other, are used to form the external teeth 31 of the external gear 3 in the gear device 1A of this basic structure. Fig.17A As shown in FIG. 1 , two external gears 3A and 3B with different phases are overlapped while the centers of the internal gear 2 are aligned. Fig.17A Extract the two superimposed trochoid curves and get Fig. 17B Shown are two curves S3 and S4.

[0230] Next, in Fig.18A Shown in Fig. 17B In the radial direction, the two curves S3 and S4 are double-layered, and the inner side is extracted to form the tooth shape of the external gear 3A (external teeth 31), and then overlapped with the internal gear 2. Here, the external gear 3A is eccentric to the right from the center of the internal gear 2 by an eccentricity of e1. Further, Fig.18B Show that Fig.16A The external gear 3A is replaced by Fig.18A The state of the external gear 3A.

[0231] Likewise, in Fig.19A Shown in Fig. 17BIn the radial direction, the two curves S3 and S4 are double-layered, and only the tooth shape of the outer gear 3B (outer teeth 31) formed on the inner side is extracted, and the state of superposition with the inner gear 2 is obtained. Here, the outer gear 3B is eccentric to the left from the center of the inner gear 2 by an eccentricity e1. Further, Fig.19B Show that Fig. 16B The external gear 3B is replaced by Fig.19A The state of the external gear 3B.

[0232] Furthermore, in order to be able to directly extract the rotation (autorotation component) of the externally-toothed gear 3 from the externally-toothed gear 3 without using a plurality of inner pins, the following structure is adopted.

[0233] Right now, Fig. 20A Shown from Fig.18B In the state shown, the inner pin 4 and the like located inside the external gear 3A are omitted, and the opening of the external gear 3A is expanded to the vicinity of the tooth bottom of the external teeth 31. Fig. 20B Shown from Fig.19B In the illustrated state, the inner pin 4 and the like located inside the external gear 3B are omitted, and the opening of the external gear 3B is expanded to the vicinity of the tooth bottom of the external teeth 31 .

[0234] and, Fig.21A The flexure generator 40A is shown embedded in Fig. 20A Here, the deflection generator 40A has a perfect circular cam 41, the center of which is eccentric to the right from the center of the internal gear 2 by an eccentricity e1. Fig.21B The flexure generator 40B is shown embedded in Fig. 20B Here, the deflection generator 40B has a perfect circular cam 41, and the center of the cam 41 is eccentric to the left from the center of the internal gear 2 by an eccentricity e1.

[0235] Then, the two sets of meshing formed by the external gears 3A and 3B in the state where the phases are shifted by 180 degrees as described above are synthesized. Fig.22A As shown, Fig. 20A and Fig. 20B The external gears 3A and 3B shown in the figure are meshed with the internal gear 2 at both end portions in the long axis direction. Fig. 20A and Fig. 20B The external gears 3A and 3B shown are extended to the side opposite to the eccentric direction (the left side in the case of the external gear 3A and the right side in the case of the external gear 3B) to obtain a non-circular (here, an oblong) external gear 3. Here, the external gears 3A and 3B are elastically deformed so that the size in the left-right direction (long axis direction) in the figure becomes larger, while the size in the up-down direction (short axis direction) in the figure becomes smaller.

[0236] However, the external gears 3A and 3B are not simply elastically deformed, but are elastically deformed in accordance with the shape of the cam 41 designed so that the external gear 3 and the internal gear 2 meet the mechanical conditions. Fig.21A The arc formed by the right half of the perfect circular cam 41 which is eccentric to the right from the center of the internal gear 2 is Fig.21B The cam 41 is designed to be an oblong shape by overlapping the arc formed by the left half of the perfect circular cam 41 eccentric to the left from the center of the internal gear 2. The cam 41 has an oblong shape formed by connecting two arcs with a pair of straight lines of length "2×e1".

[0237] Therefore, if Fig. 22B As shown, a gear mechanism 1X is obtained, which Fig.21A or Fig.21B The cam 41 is replaced with an oblong cam 41 having a pair of eccentric centers eccentric to both sides of the long axis direction (left-right direction) relative to the center of the internal gear 2. The gear mechanism 1X thus obtained has Fig.21A The gear mechanism and Fig.21B The gear mechanism 1X of the present basic structure is realized by assembling the gear mechanism 1X obtained in this way to the gear body 22 of the internal gear 2.

[0238] However, in Fig. 22B In the gear mechanism 1X shown in FIG. 1 , it is necessary that the external gear 3 does not interfere with the internal gear 2 in the non-meshing range Ra2 at both ends in the minor axis direction. Fig. 22B Zone Z1 Fig.23 As shown, at both ends of the cam 41 in the short axis direction, the tooth profile of the external gear 3 (external teeth 31) is set in such a way that the external teeth 31 of the external gear 3 do not contact the internal teeth 21 (pin 23) of the internal gear 2. Fig.23 As shown by the virtual line (double dotted line), if it is from Fig.17A In the two extracted cycloid curves S3 and S4 , the tooth height of the external teeth 31 becomes relatively large, and the external teeth 31 interfere with the internal teeth 21 at the tooth tops.

[0239] Therefore, if Fig.23As shown, in this basic structure, in the radial direction, the two curves S3 and S4 are double-layered, and only the inner curves S3 and S4 are extracted to form the tooth shape of the external tooth 31. More strictly speaking, the tooth top of the external tooth 31 has a rounded shape on the inner side of the intersection of the curves S3 and S4 in a manner that the tooth height is lower than the intersection of the curves S3 and S4. That is, in this basic structure, the external tooth 31 has a shape lacking the tooth top 311. As a result, the interference height between the external teeth 31 of the external gear 3 and the internal teeth 21 (pin 23) of the internal gear 2 becomes sufficiently small compared to the eccentricity e1, and the external gear 3 and the internal gear 2 are unlikely to interfere in the non-meshing range Ra2 at both ends in the short axis direction.

[0240] According to the tooth profile design described above, the meshing condition of the gear that transmits rotation at an equal speed ratio in mechanics can be met instead of the meshing based on the approximate tooth profile. In other words, the meshing condition of "the common normal of the contact points of the two nodes passes through the fixed point (node ​​Pp1)" is met. In other words, by ensuring the meshing that satisfies the mechanics meshing condition, the load can be dispersed. In this way, the power transmission performance can be improved, and in addition, the rotation accuracy and backlash performance can be improved.

[0241] Furthermore, in the gear device 1A of this basic structure, the deformation amount of the external gear 3 when it is elastically deformed is suppressed to be relatively small, so there is no need to make the external gear 3 extremely thin, and it is easy to ensure sufficient strength for the external gear 3. In addition, by using the pin 23 on the internal teeth 21, sliding contact is also caused at the contact part between the pin 23 and the inner peripheral groove 223, where the relative curvature radius is large and the surface pressure is small, so that it is easy to achieve improvement in the power transmission efficiency (especially the starting efficiency and the static efficiency) of the gear device 1A.

[0242] In addition, in this basic structure, in the direction of the common normal line at the contact point between the internal teeth 21 and the external teeth 31 (also the load direction), the meshing tooth profile portion (retained tooth profile) with a large load component (effective component of the load) that causes the external gear 3 to rotate is ensured, and at the same time, the meshing portion (tooth top 311 of the external teeth 31) with a small effective component of the load is eliminated to suppress the tooth height to a low level. Therefore, in the minor axis direction D2 of the external gear 3, the external teeth 31 are less likely to interfere with the internal teeth 21.

[0243] <Application Examples>

[0244] like Fig.24As shown, the gear device 1A of this basic structure, together with the first member 201 and the second member 202, constitutes a robot joint device 200 (i.e., a robot arm structure). In other words, the robot joint device 200 of this basic structure (i.e., a robot arm structure) includes the gear device 1A, the first member 201, and the second member 202. The first member 201 is fixed by the gear body 22. The second member 202 is relative to the first member 201 as the external gear 3 rotates relative to the internal gear 2. Fig.24 It is a schematic cross-sectional view of a robot joint device 200 (ie, a robot arm structure).

[0245] In this basic structure, as an example, the first member 201 is fixed by the inner ring 61, and the second member 202 is fixed by the outer ring 62. As a result, the second member 202 rotates relative to the first member 201 along with the relative rotation of the external gear 3 relative to the internal gear 2. More specifically, the first member 201 is indirectly fixed to the inner ring 61 of the bearing member 6 by being fixed to the first bracket 18. The second member 202 is indirectly fixed to the outer ring 62 of the bearing member 6 by being fixed to the second bracket 19.

[0246] The robot joint device 200 (i.e., robot arm structure) configured in this way functions as a joint device by relatively rotating the first member 201 and the second member 202 around the rotation axis Ax1. Figure 1 ) drives the cam 41 of the flexure generator 40 of the gear device 1A, so that the first member 201 and the second member 202 rotate relative to each other. At this time, the rotation (input rotation) generated by the driving source 101 is decelerated at a relatively high reduction ratio in the gear device 1A, and the first member 201 or the second member 202 is driven with a relatively high torque. That is, the first member 201 and the second member 202 connected by the gear device 1A can be flexed and extended around the rotation axis Ax1.

[0247] In more detail, a first pulley P1 is fixed to the output shaft of the first motor 203. The second pulley P2 is connected to the first pulley P1 via a timing belt T1. Here, the second pulley P2 is fixed to the cam 41 of the deflection generator 40 as a counterpart member. That is, when the first motor 203 is driven, its rotation is transmitted to the cam 41 as an input shaft via the first pulley P1, the timing belt 1 and the second pulley P2.

[0248] In addition, the robot joint device 200 (i.e., the robot mechanical arm structure) also includes a second motor 204. A third pulley P3 is fixed to the output shaft of the second motor 204. The fourth pulley P4 is connected to the third pulley P3 via a timing belt T2. Here, the fourth pulley P4 is fixed to the shaft 205. The shaft 205 passes through the gear device 1A in the direction of the rotation axis Ax1 through the interior (opening) of the cam 41. A fifth pulley P5 is fixed to the end of the shaft 205 on the opposite side of the fourth pulley P4. Thus, when the second motor 204 is driven, its rotation is transmitted to the fifth pulley P5 via the third pulley P3, the timing belt T2, the fourth pulley P4 and the shaft 205.

[0249] The robot joint device 200 (i.e., the robot mechanical arm structure) is used for a robot such as a horizontal multi-joint robot (articulated robot). Furthermore, the robot joint device 200 is not limited to a horizontal multi-joint robot, and can be used for an industrial robot other than a horizontal multi-joint robot, or a robot other than an industrial robot. In addition, the gear device 1A of this basic structure is not limited to the robot joint device 200, and can be used for a vehicle such as an unmanned guided vehicle (AGV) as a wheel device such as a wheel hub motor.

[0250] <Modification>

[0251] Basic Structure 2 is only one of various structural examples of the present invention. Basic Structure 2 can be modified in various ways according to design, etc., as long as it can achieve the purpose of the present invention. In addition, the drawings referred to in the present invention are all schematic diagrams, and the size and thickness ratios of the various structural elements in the drawings are not necessarily limited to reflect the actual dimensional ratios. The following lists the modified examples of Basic Structure 2. The modified examples described below can be appropriately combined and applied.

[0252] In addition, the bearing member 6 is not limited to the crossed roller bearing, and may be, for example, an angular contact ball bearing, a deep groove ball bearing, a four-point contact ball bearing, or the like.

[0253] In addition, the number of pins 23 (the number of teeth of the internal teeth 21) and the number of teeth of the external teeth 31 described in the basic structure 2 are merely examples and can be changed as appropriate.

[0254] In addition, 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.

[0255] In addition, the gear device 1A is not limited to a structure in which the rotational force of the outer ring 62 (the second bracket 19) is taken out as output, as long as the relative rotation between the inner ring 61 and the outer ring 62 of the bearing member 6 can be taken out as output. For example, the rotational force of the inner ring 61 (the first bracket 18) that rotates relative to the outer ring 62 can also be taken out as output.

[0256] The lubricant is not limited to liquid substances such as lubricating oil (oil), and may be a gel-like substance such as grease.

[0257] (Implementation Method 1)

[0258] like Figure 25 to Figure 27 As shown, the gear device 1C of this embodiment is different from the gear device 1A of the basic structure 2 mainly in the structure of the bearing member 6. Hereinafter, the same reference numerals are attached to the same structures as the basic structure 2, and the description thereof is omitted as appropriate. Fig.25 1C is a schematic cross-sectional view of the gear device 1C. Fig.25 In FIG. 1 , enlarged views of regions Z1 and Z2 are shown in frames. Fig.26 yes Fig.25 A1-A1 line cross-sectional view, Fig. 27 yes Fig.25 A2-A2 line section view. Figure 25 to Figure 27 In addition to Fig.25 The bearing member 6, the bearing 42, the first bearing 91 and the second bearing 92 and Fig.26 Except for the bearing member 6 in the figure, hatching is omitted even in the cross section.

[0259] The structure of the internal gear 2 itself is the same as the basic structure. In this embodiment, the internal gear 2 also has: an annular gear body 22; and a plurality of 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 state that can rotate, and constitute the internal teeth 21. Furthermore, the structure of the external gear 3 is also the same as the basic structure 2. In this embodiment, the external gear 3 is also an annular member having external teeth 31 and arranged on the inner side of the internal gear 2. The gear body 22 of the internal gear 2 has rigidity, while the external gear 3 has flexibility.

[0260] In addition, the gear device 1C of this embodiment includes a deflection generator 40 similar to the basic structure 2, which is arranged inside the external gear 3 and causes the external gear 3 to bend. The deflection generator 40 includes: a non-circular cam 41 driven to rotate around the rotation axis Ax1; and a bearing 42 mounted on the outside of the cam 41. The gear device 1C deforms the external gear 3 as the cam 41 rotates, causing a part of the external teeth 31 to mesh with a part of the internal teeth 21, thereby causing the external gear 3 to rotate relative to the rigid internal gear 2 according to the difference in the number of teeth between the external gear 3 and the internal gear 2.

[0261] In the gear device 1C of the present embodiment, the external gear 3 is bent into a non-circular shape (e.g., an oblong shape) by the deflection generator 40, so that the external teeth 31 of the external gear 3 partially mesh with the internal teeth 21 (pin 23) of the internal gear 2. In this state, when the cam 41 of the deflection generator 40 rotates, the meshing position of the internal teeth 21 and the external teeth 31 moves along the circumferential direction of the internal gear 2, and relative rotation is generated between the two gears (the internal gear 2 and the external gear 3) according to the difference in the number of teeth between the external gear 3 and the internal gear 2. Here, if the gear body 22 of the internal gear 2 is fixed, the external gear 3 rotates with the relative rotation of the two gears. As a result, a rotation output that is reduced by a relatively high reduction ratio according to the difference in the number of teeth between the two gears is obtained from the external gear 3.

[0262] In addition, if Fig.26 As shown, the tooth profile of the external teeth 31 in the external gear 3 is also the same as the basic structure 2, and a tooth profile that can achieve meshing that satisfies the meshing conditions of the gears that transmit rotation at an equal speed ratio in mechanics can be adopted, rather than meshing based on an approximate tooth profile. Specifically, the external teeth 31 have a trochoid tooth profile. The difference in the number of teeth of the external teeth 31 relative to the internal teeth 21 is a 2-piece difference. As a result, the meshing condition that "the common normal at the contact point of the two nodes passes through a fixed point (node ​​Pp1)" is satisfied. In other words, by meshing that ensures a large number of mechanical meshing conditions, load distribution can be achieved, power transmission performance can be improved, and in addition, rotation accuracy and backlash performance can be improved.

[0263] Furthermore, in the present embodiment, only the inner curves S3 and S4 are extracted from the portion where the two curves S3 and S4 form a double layer in the radial direction to form the tooth profile of the external teeth 31 (see Fig.23 ). Therefore, the tooth top of the external tooth 31 has a rounded shape on the inner side of the intersection of the curves S3 and S4 in such a way that the tooth height is lower than the intersection of the curves S3 and S4. That is, in the present embodiment, the external tooth 31 has a missing tooth top 311 (see Fig.23) shape. As a result, the interference height between the external teeth 31 of the external gear 3 and the internal teeth 21 (pin 23) of the internal gear 2 becomes sufficiently small compared to the eccentricity e1, and the external gear 3 and the internal gear 2 are unlikely to interfere with each other in the non-meshing range Ra2 at both ends in the short axis direction.

[0264] Furthermore, in the gear device 1C of the present embodiment, in the simultaneous meshing range Ra1 (see Fig.13 ), the internal teeth 21 mesh with the external teeth 31. In the present embodiment, such a simultaneous meshing range Ra1 is the same as that of the basic structure 2, and occupies more than 180 degrees of the circumference of the internal gear 2, that is, more than half. Therefore, the meshing of the internal teeth 21 and the external teeth 31 can be stabilized over a large range of more than half of the circumference of the internal gear 2. As a result, the gear device 1C is less likely to produce vibrations during operation, and tooth skipping caused by the instantaneous deviation of the meshing between the internal gear 2 and the external gear 3 when excessive torque is applied during operation.

[0265] Furthermore, in the present embodiment, the tubular portion 411 of the cam 41 as the input shaft has a hollow structure (cylindrical shape), so that, for example, other power transmission shafts, electric wires, hydraulic pipes, etc. can be arranged inside the tubular portion 411 .

[0266] However, if Fig.25 As shown, in the gear device 1C of the present embodiment, the bearing member 6 that supports the external gear 3 in a rotatable manner relative to the gear body 22 includes a first bearing member 601 and a second bearing member 602. That is, the gear device 1C includes a pair of bearing members 6 consisting of the first bearing member 601 and the second bearing member 602. The first bearing member 601 and the second bearing member 602 support the external gear 3 in a rotatable manner relative to the gear body 22 at two locations in the axial direction parallel to the rotation axis Ax1. The respective components of the first bearing member 601 and the second bearing member 602 are the same as the bearing member 6 in the basic structure 2, and include an inner ring 61, an outer ring 62, and a plurality of rolling elements 63.

[0267] Here, each of the first bearing member 601 and the second bearing member 602 directly or indirectly supports the external gear 3 in a rotatable manner relative to the gear body 22. In the present embodiment, a first bracket 18 fixed to the gear body 22 (integrated with the gear body 22) and a second bracket 19 fixed to the external gear 3 are included. Each inner ring 61 of the first bearing member 601 and the second bearing member 602 is fixed to the first bracket 18. Each outer ring 62 of the first bearing member 601 and the second bearing member 602 is fixed to the second bracket 19. Therefore, each of the first bearing member 601 and the second bearing member 602 indirectly supports the external gear 3 in a rotatable manner relative to the gear body 22 via the first bracket 18 and the second bracket 19. As a result, along with the relative rotation of the internal gear 2 and the external gear 3, the second bracket 19 (and the outer ring 62) as a movable member rotates relative to the first bracket 18 (and the inner ring 61) as a fixed member.

[0268] Specifically, if Fig.25 As shown, on the input side of the rotation axis Ax1 ( Fig.25 A first bearing member 601 is disposed on the output side ( Fig.25 The first bearing member 601 and the second bearing member 602 are configured to withstand radial loads, loads in the thrust direction (along the rotation axis Ax1), and bending forces (bending moment loads) relative to the rotation axis Ax1.

[0269] The first bearing member 601 and the second bearing member 602 are arranged in opposite directions in a direction parallel to the rotation axis Ax1 on both sides of the meshing portion of the inner teeth 21 and the outer teeth 31 in a direction parallel to the rotation axis Ax1 (axial direction). That is, the bearing member 6 is a "combined angular ball bearing" in which a plurality of (here, 2) angular ball bearings are combined. Here, as an example, the first bearing member 601 and the second bearing member 602 are "back-to-back combination type" that bears a load in a thrust direction (along the direction of the rotation axis Ax1) in which the respective outer rings 62 approach each other. Furthermore, in the gear device 1C, the first bearing member 601 and the second bearing member 602 are combined in a state where appropriate preload is applied to the outer ring 62 by tightening the respective outer rings 62 in a direction in which they approach each other.

[0270] In the present invention, the positions of the first bearing member 601 and the second bearing member 602 in the direction parallel to the rotation axis Ax1 (axial direction) are defined by the positions of the axially outer ends of the first bearing member 601 and the second bearing member 602. That is, the meshing portion of the internal teeth 21 and the external teeth 31 is located between the two axially outer ends of the first bearing member 601 and the second bearing member 602, and the first bearing member 601 and the second bearing member 602 are located on both sides of the axial direction relative to the meshing portion of the internal teeth 21 and the external teeth 31.

[0271] In addition, in the present embodiment, the cylindrical portion 411 of the cam 41 is supported by the first bearing 91 and the second bearing 92 in a rotatable manner relative to the second bracket 19. Specifically, Fig.25 As shown, the first bearing 91 and the second bearing 92 are assembled on both sides of the non-circular portion 412 in the cylindrical portion 411 in a manner of sandwiching the non-circular portion 412 in a direction parallel to the rotation axis Ax1 (axial direction). When viewed from the non-circular portion 412, the first bearing 91 is arranged on the input side of the rotation axis Ax1. When viewed from the non-circular portion 412, the second bearing 92 is arranged on the output side of the rotation axis Ax1. Thus, the cam 41 of the flexure generator 40 is maintained rotatable at two locations on both sides of the non-circular portion 412 in a direction parallel to the rotation axis Ax1. In the present embodiment, as an example, each component of the first bearing 91 and the second bearing 92 is composed of a deep groove ball bearing using a spherical ball as a rolling element.

[0272] Further, in this embodiment, if Fig. 27 As shown, the gear body 22 integrated with the first bracket 18 has a through hole 224 for passing the lubricant. The through hole 224 penetrates the gear body 22 (or the first bracket 18) in the radial direction (a direction orthogonal to the rotation axis Ax1). Here, a plurality of through holes 224 are formed with respect to the gear body 22 (six as an example). The plurality of through holes 224 are arranged at equal intervals in the circumferential direction of the gear body 22.

[0273] Here, regarding the through hole 224, Fig.25As shown, each through hole 224 is arranged between the first bearing member 601 and the second bearing member 602 in the axial direction parallel to the rotation axis Ax1. As a result, in the gap between the gear body 22 (or the first bracket 18) and the second bracket 19, the space between the first bearing member 601 and the second bearing member 602 becomes an "oil collection place" for retaining lubricant, and the lubricant is easily supplied to the meshing part of the internal teeth 21 and the external teeth 31 through the through hole 224. In particular, when the bearing member 6 (the first bearing member 601 and the second bearing member 602) is operated and the rolling element 63 rotates, the rolling element 63 functions as a pump and can send the lubricant between the first bearing member 601 and the second bearing member 602 to the meshing part through the through hole 224. In particular, the opening surface of the outer peripheral side of the through hole 224 is in a position facing (opposite) to the space between the first bearing member 601 and the second bearing member 602, so that the rolling element 63 effectively functions as a pump when the rolling element 63 rotates. As a result, the lubricant is less likely to run out at the meshing portion between the internal teeth 21 and the external teeth 31 , and the gear device 1C can operate smoothly.

[0274] As described above, in the gear device 1C of this embodiment, the bearing member 6 includes the first bearing member 601 and the second bearing member 602 that support the external gear 3 non-rotatably relative to the gear body 22 (directly or indirectly) at two locations in the axial direction parallel to the rotation axis Ax1.

[0275] In this way, by adopting a structure in which the external gear 3 (or the second bracket 19 integrated with the external gear 3) is supported by the first bearing member 601 and the second bearing member 602 at two locations in the axial direction, the rotation of the external gear 3 can be stabilized even if the external gear 3 has flexibility. As a result, there is an advantage that the meshing of the internal teeth 21 and the external teeth 31 is easy to be stabilized.

[0276] Furthermore, by adopting a structure in which the external gear 3 (or the second bracket 19) is supported by the first bearing member 601 and the second bearing member 602 at two locations in the axial direction, it is easy to achieve an improvement in the adjustment accuracy of the clearance or preload of the first bearing member 601 and the second bearing member 602. That is, when assembling the gear device 1C, it is possible to prepare an intermediate product in a state in which the first bearing member 601 and the second bearing member 602 are assembled to the external gear 3 (or the second bracket 19), and then combine the intermediate product with the internal gear 2, etc. As a result, the assembly of the first bearing member 601 and the second bearing member 602, which requires the adjustment accuracy of the clearance or preload, can be separated from the overall assembly work of the gear device 1C, which is associated with the improvement of the adjustment accuracy of the clearance or preload of the first bearing member 601 and the second bearing member 602.

[0277] In addition, in the present embodiment, the first bearing member 601 and the second bearing member 602 are located on both sides of the meshing portion of the internal teeth 21 and the external teeth 31 in the axial direction (in the direction parallel to the rotation axis Ax1). In other words, in the axial direction (in the direction parallel to the rotation axis Ax1), the meshing portion of the internal teeth 21 and the external teeth 31 is located between (the two ends of the outer sides of) the first bearing member 601 and the second bearing member 602. As a result, the inclination of the internal teeth 21 (pin 23) or the external teeth 31 relative to the rotation axis Ax1 is suppressed, and the meshing of the internal teeth 21 and the external teeth 31 is easily stabilized.

[0278] In addition, in the present embodiment, the first bearing member 601 and the second bearing member 602 are located on both sides of the flexure generator 40 in the axial direction (in the direction parallel to the rotation axis Ax1). In other words, in the axial direction (in the direction parallel to the rotation axis Ax1), the flexure generator 40 is located between (the outer ends of) the first bearing member 601 and the second bearing member 602. As a result, the inclination of the internal teeth 21 (pin 23) or the external teeth 31 relative to the rotation axis Ax1 is suppressed, and the meshing of the internal teeth 21 and the external teeth 31 is easily stabilized.

[0279] In short, in the axial direction, there is no planetary gear like the external gear 3 of the basic structure 1 between the first bearing member 601 and the second bearing member 602 .

[0280] The gear device 1C of this embodiment is, for example, Fig.28 As shown, the robot joint device 200 (i.e., the robot arm structure) is constituted together with the first member 201 and the second member 202. In other words, the robot joint device 200 (i.e., the robot arm structure) of the present embodiment includes the gear device 1C, the first member 201 and the second member 202. The first member 201 is fixed by the gear body 22. The second member 202 is relative to the first member 201 as the external gear 3 rotates relative to the internal gear 2. Fig.28 It is a schematic cross-sectional view of the robot joint device 200 .

[0281] In the present embodiment, as an example, the first member 201 is fixed by the inner ring 61, and the second member 202 is fixed by the outer ring 62. Thus, the second member 202 rotates relative to the first member 201 along with the relative rotation of the external gear 3 relative to the internal gear 2. More specifically, the first member 201 is indirectly fixed to the inner ring 61 of the bearing member 6 by being fixed to the first bracket 18. The second member 202 is indirectly fixed to the outer ring 62 of the bearing member 6 by being fixed to the second bracket 19.

[0282] In addition, Fig.28In the example of FIG. 6 , the inner ring 61 of the second bearing member 602 is seamlessly integrated with the input shaft (the first bracket 18 to which the first member 201 is fixed).

[0283] Implementation method one is only one of various implementation methods of the present invention. Implementation method one can be modified in various ways according to design, etc., as long as it can achieve the purpose of the present invention. The structure of implementation method one can be appropriately combined with various structures (including modified examples) described in basic structure one or basic structure two. In addition, the drawings referred to in the present invention are all schematic diagrams, and the size and thickness ratios of the various structural elements in the drawings are not necessarily limited to reflect the actual dimensional ratios. The following lists modified examples of implementation method one. The modified examples described below can be appropriately combined and applied.

[0284] As a modification of the first embodiment, the first bearing member 601 and the second bearing member 602 do not need to be angular ball bearings. For example, at least one of the first bearing member 601 and the second bearing member 602 may be a deep groove ball bearing, a tapered roller bearing, a cylindrical roller bearing, or a cross roller bearing.

[0285] In addition, the first bearing member 601 and the second bearing member 602 do not need to be located on both sides of the meshing portion of the inner teeth 21 and the outer teeth 31 and / or the flexure generator 40 in the axial direction. For example, the first bearing member 601 and the second bearing member 602 may be located on one side of the meshing portion of the inner teeth 21 and the outer teeth 31, or on one side of the flexure generator 40 in the axial direction.

[0286] (Implementation Method 2)

[0287] like Fig.29 As shown, the gear device 1B of this embodiment is different from the gear device 1C of the first embodiment in that the cam 41 of the deflection generator 40 has an elliptical shape. Hereinafter, the same reference numerals are used for the same configurations as those of the first embodiment, and description thereof is omitted as appropriate. Fig.29 2 is a cross-sectional view showing a schematic structure of the gear device 1B. Fig.29 In the figure, hatching is omitted even in cross-section, and the inner peripheral surface 221 of the gear body 22 is omitted from illustration.

[0288] That is, in the present embodiment, the cam 41 has an elliptical shape. The "elliptical shape" mentioned in the present invention refers to a shape in which a perfect circle is flattened so that the intersection of the long axis (long axis direction D1) and the short axis (short axis direction D2) that are orthogonal to each other is located at the center, and is not limited to a curve consisting of a set of points whose sum of distances from two fixed points on a plane is constant, that is, a mathematical "ellipse". That is, the cam 41 in the present embodiment may also be a curve consisting of a set of points whose sum of distances from two fixed points on a plane is constant, like a mathematical "ellipse", or may be an elliptical shape other than a mathematical "ellipse".

[0289] like Fig.29 As shown, in the gear device 1B of this embodiment, the external teeth 31 located at both ends of the elliptical shape in the major axis direction D1 mesh with the internal teeth 21 . In contrast, the external teeth 31 located at both ends of the elliptical shape in the minor axis direction D2 do not mesh with the internal teeth 21 .

[0290] The structure of the second embodiment can be appropriately combined with the various structures (including modified examples) described in the first embodiment.

[0291] (Summarize)

[0292] As described above, the first form of the gear device (1, 1A, 1B, 1C) includes an internal gear (2), an annular external gear (3), a deflection generator (40) and a bearing member (6). The internal gear (2) has: an annular gear body (22); and a plurality of pins (23) which are held in a state of being able to rotate in a plurality of inner peripheral grooves (223) formed on the inner peripheral surface (221) of the gear body (22) and constitute the internal teeth (21). The external gear (3) has external teeth (31) and is arranged on the inner side of the internal gear (2). The deflection generator (40) has: a non-circular cam (41) which is driven to rotate around a rotation axis (Ax1); and a bearing (42) which is assembled on the outer side of the cam (41). The deflection generator (40) is arranged on the inner side of the external gear (3) and causes the external gear (3) to bend. The gear device (1, 1A, 1B, 1C) deforms the external gear (3) as the cam (41) rotates, causing a portion of the external teeth (31) to mesh with a portion of the internal teeth (21), thereby causing the external gear (3) to rotate relative to the internal gear (2) according to the difference in the number of teeth between the external gear (3) and the internal gear (2). The bearing component (6) has a first bearing component (601) and a second bearing component (602) that rotatably support the external gear (3) relative to the gear body (22) at two locations in the axial direction parallel to the rotation axis (Ax1).

[0293] According to this embodiment, the external gear (3) is supported by the first bearing member (601) and the second bearing member (602) at two locations in the axial direction, so that the rotation of the external gear (3) can be stabilized despite the flexibility of the external gear (3). As a result, there is an advantage that the meshing of the internal teeth (21) and the external teeth (31) is easy and stable.

[0294] In a second form of the gear device (1, 1A, 1B, 1C), based on the first form, the internal teeth (21) mesh with the external teeth (31) within a simultaneous meshing range (Ra1) occupying more than 180 degrees in the circumferential direction of the internal gear (2).

[0295] According to this embodiment, within a simultaneous meshing range (Ra1) of more than half of the circumference of the internal gear (2), the external gear (3) is constrained by the internal gear (2), thereby suppressing the movement (deformation) of the external gear (3) in a direction away from the flexure generator (40). Therefore, the meshing of the internal teeth (21) and the external teeth (31) can be stabilized over a large range of more than half of the circumference of the internal gear (2). In other words, there is an advantage of easily stabilizing the meshing of the internal teeth (21) and the external teeth (31). As a result, the gear device (1, 1A, 1B, 1C) is less likely to produce vibrations during operation, and tooth skipping caused by the instantaneous deviation of the meshing between the internal gear (2) and the external gear (3) when excessive torque is applied during operation. In other words, according to the gear device (1, 1A, 1B, 1C), a structure with low vibration and improved impact resistance can be achieved.

[0296] In the third form of the gear device (1, 1A, 1B, 1C), based on the first or second form, the first bearing component (601) and the second bearing component (602) are located on both sides of the meshing position of the internal teeth (21) and the external teeth (31) in the axial direction.

[0297] According to this aspect, the inclination of the internal teeth (21) or the external teeth (31) relative to the rotation axis (Ax1) is suppressed, and the meshing of the internal teeth (21) and the external teeth (31) is easily stabilized.

[0298] In a fourth aspect of the gear device (1, 1A, 1B, 1C), in addition to any one of the first to third aspects, the first bearing member (601) and the second bearing member (602) are located on both sides of the deflection generator (40) in the axial direction.

[0299] According to this aspect, the inclination of the internal teeth (21) or the external teeth (31) relative to the rotation axis (Ax1) is suppressed, and the meshing of the internal teeth (21) and the external teeth (31) is easily stabilized.

[0300] In the gear device (1, 1A, 1B, 1C) of the fifth aspect, based on any one of the first to fourth aspects, the external teeth (31) have a trochoid tooth profile, and the number of teeth of the external teeth (31) differs from that of the internal teeth (21) by two.

[0301] According to this aspect, as the tooth profile of the external teeth (31) in the external gear (3), meshing that satisfies the meshing conditions of the gears that transmit rotation at an equal speed ratio in mechanics can be achieved, rather than meshing based on an approximate tooth profile. As a result, meshing that satisfies the meshing conditions in mechanics can be ensured, load dispersion can be achieved, and stress concentration on the external gear (3) is less likely to occur by suppressing the deformation of the external gear (3) to a small amount.

[0302] In a gear device (1, 1A, 1B, 1C) of a sixth aspect, in addition to the fifth aspect, the external teeth (31) have a shape lacking tooth tops (311).

[0303] According to this aspect, in the non-meshing range (Ra2) where the inner teeth (21) and the outer teeth (31) do not mesh, interference between the inner teeth (21) and the outer teeth (31) is unlikely to occur.

[0304] The seventh form of the robot joint device (200) includes: a gear device (1, 1A, 1B, 1C) of any one of the first to seventh forms; a first component (201) fixed to the gear body (22); and a second component (202) that rotates relative to the first component (201) as the external gear (3) rotates relative to the internal gear (2).

[0305] According to this aspect, there is an advantage that the meshing between the internal teeth (21) and the external teeth (31) can be easily stabilized.

[0306] The structures of the second to sixth embodiments are not necessary for the gear device (1, 1A, 1B, 1C) and can be omitted as appropriate.

Claims

1. A robot arm structure, comprising a robot joint device, wherein: The robot joint device comprises: The gear device comprises: an internal gear having: an annular gear body; and a plurality of pins held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a state capable of self-rotation and constituting internal teeth; an annular external gear having external teeth and arranged on the inner side of the internal gear; a deflection generator having a non-circular cam driven to rotate around a rotation axis and a bearing mounted on the outer side of the cam, the deflection generator being arranged on the inner side of the external gear to cause the external gear to bend; and a bearing member, wherein the gear device deforms the external gear as the cam rotates so that a portion of the external teeth meshes with a portion of the internal teeth, thereby causing the external gear to rotate relative to the internal gear according to a difference in the number of teeth between the external gear and the internal gear, and the bearing member having a first bearing member and a second bearing member that support the external gear at two locations in an axial direction parallel to the rotation axis so as to be rotatable relative to the gear body; 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 externally-toothed gear with respect to the internally-toothed gear.

2. A gear device, wherein: include: An internal gear comprises: an annular gear body; and a plurality of pins held in a plurality of inner peripheral grooves formed on the inner peripheral surface of the gear body in a rotatable state to constitute internal teeth; an annular external gear having external teeth and arranged inside the internal gear; a deflection generator having a non-circular cam driven to rotate about a rotation axis and a bearing mounted on the outer side of the cam, wherein the deflection generator is arranged on the inner side of the external gear to cause the external gear to bend; and Bearing components, The gear device deforms the external gear as the cam rotates, causing a portion of the external teeth to mesh with a portion of the internal teeth, thereby causing the external gear to rotate relative to the internal gear in accordance with a difference in the number of teeth between the external gear and the internal gear. The bearing member includes a first bearing member and a second bearing member that support the externally toothed gear at two locations in the axial direction parallel to the rotation axis so as to be rotatable relative to the gear body.

3. The gear device according to claim 2, wherein: The internal teeth mesh with the external teeth within a simultaneous meshing range occupying 180 degrees or more in the circumferential direction of the internal gear.

4. The gear device according to claim 2 or 3, wherein: The first bearing member and the second bearing member are located on both sides of a meshing portion between the internal teeth and the external teeth in the axial direction.

5. The gear device according to claim 2 or 3, wherein: The first bearing member and the second bearing member are located on both sides of the flexure generator in the axial direction.

6. The gear device according to claim 2 or 3, wherein: The external teeth have a trochoid tooth shape, The difference in the number of teeth of the external teeth relative to the number of teeth of the internal teeth is 2 teeth.

7. The gear device according to claim 6, wherein: The outer teeth have a shape lacking tooth tops.

8. A joint device for a robot, wherein: include: The gear device according to claim 2 or 3; 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 externally-toothed gear with respect to the internally-toothed gear.

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