JP2023169990A - Inner gearing planetary gear device, joint device for robot, and wave gear device - Google Patents

Abstract

To provide an inner gearing planetary gear device capable of reducing vibration generating on an engagement region between gears, a joint device for a robot, and a wave gear device.SOLUTION: An inner gearing planetary gear device 1A includes an internal gear 2 and a planetary gear 3. The internal gear 2 has an annular gear main body 22, and a plurality of outer pins 23 constituting internal teeth 21 rotatably retained in a plurality of inner peripheral grooves formed on an inner peripheral face of the gear main body 22. The planetary gear 3 has external teeth partially engaged with the internal teeth 21. The inner gearing planetary gear device 1A rotates the planetary gear 3 relatively to the internal gear 2 by oscillating the planetary gear 3 about a rotating shaft Ax1 as a center. Engagement phases different from each other are generated in the oscillation of the planetary gear 3 at engagement regions with a plurality of second gears, of a first gear about the rotating shaft Ax1 as the center.SELECTED DRAWING: Figure 13

Description

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

As a related technology, an eccentric oscillation type internal meshing planetary gear device called a distribution type is known (see, for example, Patent Document 1). The internally meshing planetary gear device according to related technology includes a plurality of (for example, three) crankshafts arranged at positions offset from the axis of the internal gear, and each crankshaft is driven synchronously by the crankshaft gear. By doing so, the planetary gear (external gear) is internally engaged with the internal gear while being oscillated.

The planetary gears include a first planetary gear and a second planetary gear. A pair of carriers are arranged on both sides of the first planetary gear and the second planetary gear in the axial direction. Each crankshaft is supported by a pair of carriers via a pair of tapered roller bearings. When the input gear rotates, the three crankshaft gears meshing with the input gear at the same time rotate in the same direction and at the same rotational speed. Since the crankshaft is spline-connected to each crankshaft gear, the three crankshafts rotate in the same direction at the same rotational speed while being reduced in speed to the ratio of the number of teeth between the input gear and the crankshaft gear. As a result, the three first eccentric parts formed at the same axial position of the three crankshafts rotate synchronously and swing the first planetary gear, and the three first eccentric parts are formed at the same axial position of the three crankshafts. The three second eccentric parts thus formed rotate synchronously to swing the second planetary gear.

The first planetary gear and the second planetary gear are each internally meshed with the internal gear. The internal gear includes a gear main body and an outer pin (pin member) that is rotatably incorporated into the gear main body and constitutes an internal tooth of the internal gear. Here, the number of teeth of the internal gear (the number of external pins) is slightly greater than the number of teeth of each planetary gear. Therefore, each time each planetary gear oscillates once, the first planetary gear and the second planetary gear are out of phase with respect to the internal gear in the circumferential direction (rotate), and this rotation causes each It is transmitted to a pair of carriers as revolution around the axis (rotation axis) of the internal gear of the crankshaft. Thereby, the pair of carriers can be rotated relative to the gear body (and the casing integrated therewith) around the rotation axis.

Japanese Patent Application Publication No. 2016-75354

In the above-mentioned related technology, for example, between gears such as an internal gear and a planetary gear (a first planetary gear and a second planetary gear), vibrations in the circumferential direction of the internal gear due to meshing transmission errors and the radius of the internal gear Directional vibrations may occur.

An object of the present disclosure is to provide an internally coupled planetary gear device, a joint device for a robot, and a wave gear device that can reduce vibrations occurring in meshing portions between gears.

An internally meshing planetary gear device according to one aspect of the present disclosure includes an internal gear and a planetary gear. The internal gear has an annular gear main body and a plurality of outer pins that are rotatably held in a plurality of inner circumferential grooves formed on the inner circumferential surface of the gear main body and constitute internal teeth. The planetary gear has external teeth that partially mesh with the internal teeth. The internal meshing planetary gear device rotates the planetary gears relative to the internal gears by swinging the planetary gears about a rotation axis. When the planetary gear swings, different meshing phases occur between the meshing portions of the first gear with the plurality of second gears centered on the rotation axis.

A joint device for a robot according to an aspect of the present disclosure includes the internal meshing planetary gear device, a first member fixed to the gear main body, and a joint device for a robot according to relative rotation of the planetary gear with respect to the internal gear. , and a second member that rotates relative to the first member.

A wave gear device according to one aspect of the present disclosure includes an annular rigid internal gear having internal teeth, an annular flexible external gear having external teeth, and a wave generator. The flexible external gear is arranged inside the rigid internal gear. The wave generator is disposed inside the flexible external gear, and causes the flexible external gear to deflect. In the wave gear device, the flexible external gear is deformed as the wave generator rotates about the rotation axis, and a part of the external tooth meshes with a part of the internal tooth, The flexible external gear is rotated relative to the rigid internal gear according to the difference in the number of teeth between the flexible external gear and the rigid internal gear. When the wave generator rotates, different meshing phases occur between the plurality of meshing portions of the internal teeth with the external teeth.

According to the present disclosure, it is possible to provide an internal joint planetary gear device, a joint device for a robot, and a strain wave gear device that can reduce vibrations generated in meshing portions between gears.

FIG. 1 is a perspective view showing a schematic configuration of an actuator including an internal meshing planetary gear device according to a basic configuration. FIG. 2 is a schematic exploded perspective view of the internal meshing planetary gear device seen from the output side of the rotating shaft. FIG. 3 is a schematic sectional view of the internal meshing planetary gear device same as the above. FIG. 4 is a sectional view taken along the line A1-A1 in FIG. 3, showing the internally meshing planetary gear device as described above. FIG. 5A is a perspective view showing a single planetary gear of the internally meshing planetary gear device as described above. FIG. 5B is a front view showing a single planetary gear of the internally meshing planetary gear device according to the above. FIG. 6A is a perspective view showing a single bearing member of the internal meshing planetary gear device as described above. FIG. 6B is a front view showing the bearing member of the internal meshing planetary gear device as a single unit. FIG. 7A is a perspective view showing the eccentric shaft of the internal meshing planetary gear device as a single unit. FIG. 7B is a front view showing the eccentric shaft of the internal meshing planetary gear device as a single unit. FIG. 8A is a perspective view showing a single support body of the internally meshing planetary gear device according to the above. FIG. 8B is a front view showing the support body of the internal meshing planetary gear device as a single unit. FIG. 9 is an enlarged view of region Z1 in FIG. 3, showing the internally meshing planetary gear device same as above. FIG. 10 is a sectional view taken along the line B1-B1 in FIG. 3, showing the internally meshing planetary gear device as described above. FIG. 11 is a perspective view showing a schematic configuration of an internally meshing planetary gear device according to the first embodiment. FIG. 12 is a schematic exploded perspective view of the internal meshing planetary gear device seen from the input side of the rotating shaft. FIG. 13 is a schematic sectional view of the internal meshing planetary gear device same as above. FIG. 14 is a schematic diagram showing the relationship between the input gear and a plurality of crankshaft gears of the internally meshing planetary gear device according to the above. FIG. 15 shows circumferential vibrations due to meshing transmission errors occurring between the input gear and a plurality of crankshaft gears for each of the internal meshing planetary gear device, the first comparative example, and the second comparative example. It is an explanatory view shown typically. FIG. 16 is an explanatory diagram schematically showing the relationship between an input gear and a pair of crankshaft gears in the internally meshing planetary gear device as described above. FIG. 17 is a schematic cross-sectional view of an internally meshing planetary gear device according to a second embodiment. FIG. 18 is a sectional view taken along the line A1-A1 in FIG. 17, showing the internally meshing planetary gear device same as the above. FIG. 19 is a sectional view taken along the line B1-B1 in FIG. 17, showing the internally meshing planetary gear device same as the above. FIG. 20 is a schematic diagram showing the relationship between an internal gear and a plurality of planetary gears in the internally meshing planetary gear device. FIG. 21 shows the circumferential vibration caused by the mesh transmission error between the internal gear and the plurality of planetary gears for each of the internally meshing planetary gear device, the first comparative example, and the second comparative example. It is an explanatory view shown typically. FIG. 22 is a schematic cross-sectional view showing a robot joint device using the internal meshing planetary gear device as described above. FIG. 23 is a sectional view showing a schematic configuration of a wave gear device according to the third embodiment. FIG. 24 is a schematic diagram of the strain wave gear device seen from the input side of the rotating shaft. FIG. 25 is a schematic exploded perspective view of the wave gear device seen from the output side of the rotating shaft. FIG. 26 is a schematic exploded perspective view of the wave gear device seen from the input side of the rotating shaft.

(Basic configuration)
(1) Overview Hereinafter, an overview of the internal meshing planetary gear device 1 according to the present basic configuration will be described with reference to FIGS. 1 to 3. The drawings referred to in this disclosure are all schematic diagrams, and the ratios of the sizes and thicknesses of each component in the drawings do not necessarily reflect the actual dimensional ratios. For example, the tooth profile, dimensions, number of teeth, etc. of the internal teeth 21 and external teeth 31 in FIGS. 1 to 3 are merely shown schematically for explanation, and are limited to the shapes shown in the figures. That's not the purpose.

The internal meshing planetary gear device 1 (hereinafter also simply referred to as “gear device 1”) according to the present basic configuration is a gear device including an internal gear 2, a planetary gear 3, and a plurality of internal pins 4. . In this gear device 1, a planetary gear 3 is arranged inside an annular internal gear 2, and an eccentric bearing 5 is further arranged inside the planetary gear 3. The eccentric bearing 5 has an eccentric inner ring 51 and an eccentric outer ring 52, and the eccentric inner ring 51 rotates around a rotation axis Ax1 (see FIG. 3) that is offset from the center C1 of the eccentric inner ring 51 (see FIG. 3). (eccentric movement) causes the planetary gear 3 to swing. The eccentric inner ring 51 rotates (eccentric movement) around the rotation axis Ax1, for example, when the eccentric shaft 7 inserted into the eccentric inner ring 51 rotates. Further, the internal meshing planetary gear device 1 further includes a bearing member 6 having an outer ring 62 and an inner ring 61. The inner ring 61 is disposed inside the outer ring 62 and is rotatably supported relative to the outer ring 62.

The internal gear 2 has internal teeth 21 and is fixed to an outer ring 62. In particular, in this basic configuration, the internal gear 2 includes an annular gear main body 22 and a plurality of external pins 23. The plurality of outer pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state, and constitute the inner teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. That is, the planetary gear 3 is inscribed in the internal gear 2 inside the internal gear 2, and a portion of the external teeth 31 meshes with a portion of the internal teeth 21. In this state, when the eccentric shaft 7 rotates, the planetary gear 3 swings, and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2. A relative rotation occurs between both gears (internal gear 2 and planetary gear 3) according to the difference in the number of teeth between the two gears. Here, if the internal gear 2 is fixed, the planetary gear 3 will rotate (rotate) as the two gears rotate relative to each other. As a result, a rotational output is obtained from the planetary gear 3, which is reduced at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

This type of gear device 1 is used so that rotation corresponding to the autorotation component of the planetary gear 3 is extracted as rotation of an output shaft integrated with the inner ring 61 of the bearing member 6, for example. Thereby, the gear device 1 functions as a gear device with a relatively high reduction ratio, with the eccentric shaft 7 on the input side and the output shaft on the output side. Therefore, in the gear device 1 according to the present basic configuration, in order to transmit the rotation equivalent to the autorotation component of the planetary gear 3 to the inner ring 61 of the bearing member 6, the planetary gear 3 and the inner ring 61 are connected by the plurality of inner pins 4. Link. The plurality of inner pins 4 are inserted into the plurality of loose fitting holes 32 formed in the planetary gear 3, and rotate relative to the internal gear 2 while revolving within the respective loose fitting holes 32. . That is, the loose fit hole 32 has a larger diameter than the inner pin 4, and the inner pin 4 is movable so as to revolve within the loose fit hole 32 while being inserted into the loose fit hole 32. The oscillation component of the planetary gear 3, that is, the revolution component of the planetary gear 3, is absorbed by the loose fit between the loose fit hole 32 of the planetary gear 3 and the inner pin 4. In other words, the oscillation component of the planetary gear 3 is absorbed by the plurality of inner pins 4 moving so as to revolve within the plurality of loose fitting holes 32, respectively. Therefore, the rotation (rotation component) of the planetary gear 3 excluding the oscillation component (revolution component) of the planetary gear 3 is transmitted to the inner ring 61 of the bearing member 6 by the plurality of inner pins 4 .

By the way, in this type of gear device 1, the rotation of the planetary gear 3 is transmitted to the plurality of inner pins 4 while the inner pin 4 revolves within the loose fitting hole 32 of the planetary gear 3. It is known to use an inner roller that is attached to the inner pin 4 and is rotatable around the inner pin 4. That is, in the first related technology, the inner pin 4 is held in a press-fitted state into the inner ring 61 (or a carrier integrated with the inner ring 61), and the inner pin 4 is held in a state in which it is press-fitted into the inner ring 61 (or a carrier integrated with the inner ring 61). During the revolution, the inner pin 4 slides on the inner circumferential surface 321 of the loose fitting hole 32. Therefore, as a first related technique, an inner roller is used in order to reduce the loss due to the frictional resistance between the inner circumferential surface 321 of the loose fitting hole 32 and the inner pin 4. However, if the configuration includes an inner roller as in the first related technology, the loose fit hole 32 needs to have a diameter that allows the inner pin 4 with the inner roller to revolve, and the size of the loose fit hole 32 can be reduced. Have difficulty. If it is difficult to downsize the loose fitting hole 32, this will hinder the downsizing of the planetary gear 3 (particularly downsizing), and in turn, the downsizing of the gear device 1 as a whole. The gear device 1 according to the present basic configuration makes it possible to provide an internal meshing planetary gear device 1 that is easy to downsize due to the following configuration.

That is, the gear device 1 according to the present basic configuration includes a bearing member 6, an internal gear 2, a planetary gear 3, and a plurality of internal pins 4, as shown in FIGS. 1 to 3. The bearing member 6 has an outer ring 62 and an inner ring 61 disposed inside the outer ring 62. Inner ring 61 is rotatably supported relative to outer ring 62. The internal gear 2 has internal teeth 21 and is fixed to an outer ring 62. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The plurality of inner pins 4 are inserted into the plurality of loosely fitting holes 32 formed in the planetary gear 3, and rotate relative to the internal gear 2 while revolving within the loosely fitting holes 32. Here, each of the plurality of inner pins 4 is held by the inner ring 61 in a rotatable state. Furthermore, 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.

According to this aspect, each of the plurality of inner pins 4 is held in the inner ring 61 in a rotatable state, so that when the inner pin 4 revolves within the loose fitting hole 32, the inner pin 4 itself can rotate. It is. Therefore, the loss due to the frictional resistance between the inner circumferential surface 321 of the loose fitting hole 32 and the inner pin 4 can be reduced without using an inner roller that is attached to the inner pin 4 and is rotatable around the inner pin 4. Therefore, the gear device 1 according to this basic configuration does not require an inner roller, and has the advantage of being easy to downsize. Furthermore, since 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, the dimensions of the gear device 1 in the axial direction of the bearing member 6 can be kept small. Can be done. In other words, compared to a configuration in which the bearing member 6 and the inner pin 4 are lined up (opposing each other) in the axial direction of the bearing member 6, in the gear device 1 according to this basic configuration, the dimensions of the gear device 1 in the axial direction can be reduced. , it is possible to contribute to further miniaturization (thinness) of the gear device 1.

Furthermore, if the dimensions of the planetary gear 3 are the same as those of the first related technology, for example, the number of inner pins 4 may be increased to smooth the transmission of rotation, compared to the first related technology. It is also possible to increase the strength of the inner pin 4 by making it thicker.

Further, in this type of gear device 1, the inner pins 4 need to revolve within the loose fitting holes 32 of the planetary gears 3. Therefore, as a second related technique, the plurality of inner pins 4 are connected to the inner ring 61 (or inner ring 61). It may be held only by a carrier (integrated with a carrier). According to the second related technique, it is difficult to improve the precision of centering the plurality of inner pins 4, and poor centering may lead to problems such as generation of vibration and reduction in transmission efficiency. That is, each of the inner pins 4 rotates relative to the internal gear 2 while revolving within the loose fitting hole 32, thereby transmitting the rotational component of the planetary gear 3 to the inner ring 61 of the bearing member 6. do. At this time, if the accuracy of the centering of the plurality of inner pins 4 is insufficient and the rotation axis of the plurality of inner pins 4 is shifted or tilted with respect to the rotation axis of the inner ring 61, a state of centering failure will occur. This may lead to problems such as generation of vibration and reduction in transmission efficiency. The gear device 1 according to the present basic configuration makes it possible to provide an internally meshing planetary gear device 1 that is less prone to problems caused by poor centering of the plurality of inner pins 4 due to the following configuration.

That is, the gear device 1 according to the present basic configuration includes an internal gear 2, a planetary gear 3, a plurality of internal pins 4, and a support body 8, as shown in FIGS. 1 to 3. The internal gear 2 includes an annular gear main body 22 and a plurality of external pins 23. The plurality of outer pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state and constitute the inner teeth 21. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The plurality of inner pins 4 are inserted into the plurality of loosely fitting holes 32 formed in the planetary gear 3, and rotate relative to the gear body 22 while revolving within the loosely fitting holes 32. The support body 8 is annular and supports the plurality of inner pins 4. Here, the position of the support body 8 is regulated by bringing the outer peripheral surface 81 into contact with the plurality of outer pins 23 .

According to this aspect, since the plurality of inner pins 4 are supported by the annular support 8, the plurality of inner pins 4 are bundled by the support 8, and the relative displacement of the plurality of inner pins 4 is and tilt is suppressed. Moreover, the outer circumferential surface 81 of the support body 8 contacts the plurality of outer pins 23, thereby regulating the position of the support body 8. In short, the support body 8 is centered by the plurality of outer 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 outer pins 23. . Therefore, the gear device 1 according to the present basic configuration has the advantage that it is easy to improve the precision of centering the plurality of inner pins 4, and problems caused by poor centering of the plurality of inner pins 4 are less likely to occur. .

Further, the gear device 1 according to the present basic configuration constitutes an actuator 100 together with a drive source 101, as shown in FIG. In other words, the actuator 100 according to the present basic configuration includes the gear device 1 and the drive source 101. The drive source 101 generates a driving force for swinging the planetary gear 3. Specifically, the drive source 101 causes the planetary gear 3 to swing by rotating the eccentric shaft 7 about the rotation axis Ax1.

(2) Definition "Annular" as used in the present disclosure means a ring-like shape that forms a space (region) surrounded by the inner side, at least in plan view, and is similar to a perfect circle in plan view. The shape is not limited to an annular shape, and may be, for example, an elliptical shape or a polygonal shape. Furthermore, even if the shape has a bottom, such as a cup shape, if the peripheral wall thereof is annular, it is included in the "annular shape".

In the present disclosure, "loose fitting" means being fitted with play (gap), and the loose fitting hole 32 is a hole into which the inner pin 4 is loosely fitted. That is, the inner pin 4 is inserted into the loose fit hole 32 with a spatial margin (gap) secured between it and the inner circumferential surface 321 of the loose fit hole 32. In other words, the diameter of at least the portion of the inner pin 4 that is inserted into the loose fit hole 32 is smaller (thinner) than the diameter of the loose fit hole 32 . Therefore, the inner pin 4 is movable within the loose fit hole 32 while being inserted into the loose fit hole 32, that is, movable relative to the center of the loose fit hole 32. Therefore, the inner pin 4 can revolve within the loose fitting hole 32. However, it is not essential to ensure a gap as a cavity between the inner circumferential surface 321 of the loose fitting hole 32 and the inner pin 4. For example, even if this gap is filled with a fluid such as liquid, good.

"Revolution" in the present disclosure means that an object revolves around a rotation axis other than the central axis passing through the center (center of gravity) of this object, and when an object revolves, the center of this object revolves around the rotation axis. It will move along an orbit centered on . Therefore, for example, if an object rotates around an eccentric axis that is parallel to the central axis passing through the center (center of gravity) of the object, this object will revolve around the eccentric axis as the rotation axis. . As an example, the inner pin 4 revolves around the rotation axis passing through the center of the loose fit hole 32 .

Further, in the present disclosure, one side of the rotation axis Ax1 (the left side in FIG. 3) may be referred to as the "input side", and the other side of the rotation axis Ax1 (the right side in FIG. 3) may be referred to as the "output side". In the example of FIG. 3, rotation is applied to the rotating body (eccentric inner ring 51) from the "input side" of the rotation axis Ax1, and rotation of the plurality of inner pins 4 (inner ring 61) is applied from the "output side" of the rotation axis Ax1. taken out. However, "input side" and "output side" are merely labels added for the purpose of explanation, and are not intended to limit the positional relationship between the input and output as seen from the gear device 1.

The "rotation axis" in the present disclosure means a virtual axis (straight line) that is the center of the rotational movement of a rotating body. In other words, the rotation axis Ax1 is a virtual axis with no substance. The eccentric inner ring 51 rotates around the rotation axis Ax1.

In the present disclosure, "internal teeth" and "external teeth" each mean a set (group) of a plurality of "teeth" rather than a single "teeth." That is, the internal teeth 21 of the internal gear 2 are composed of a plurality of teeth arranged on the inner circumferential surface 221 of the internal gear 2 (gear main body 22). Similarly, the external teeth 31 of the planetary gear 3 are composed of a plurality of teeth arranged on the outer peripheral surface of the planetary gear 3.

(3) Configuration Hereinafter, the detailed configuration of the internally meshing planetary gear device 1 according to the present basic configuration will be explained with reference to FIGS. 1 to 8B.

FIG. 1 is a perspective view showing a schematic configuration of an actuator 100 including a gear device 1. As shown in FIG. In FIG. 1, a drive source 101 is schematically shown. FIG. 2 is a schematic exploded perspective view of the gear device 1 viewed from the output side of the rotating shaft Ax1. FIG. 3 is a schematic cross-sectional view of the gear device 1. FIG. 4 is a sectional view taken along line A1-A1 in FIG. However, in FIG. 4, hatching is omitted for parts other than the eccentric shaft 7 even in the cross section. Furthermore, in FIG. 4, illustration of the inner circumferential surface 221 of the gear body 22 is omitted. 5A and 5B are a perspective view and a front view showing the planetary gear 3 alone. 6A and 6B are a perspective view and a front view showing the bearing member 6 alone. 7A and 7B are a perspective view and a front view showing the eccentric shaft 7 alone. 8A and 8B are a perspective view and a front view showing the support body 8 alone.

(3.1) Overall configuration As shown in FIGS. 1 to 3, the gear device 1 according to the present basic configuration includes an internal gear 2, a planetary gear 3, a plurality of internal pins 4, and an eccentric bearing 5. , a bearing member 6, an eccentric shaft 7, and a support body 8. Furthermore, in this basic configuration, the gear device 1 further includes a first bearing 91, a second bearing 92, and a case 10. In this basic configuration, the materials of the internal gear 2, the planetary gear 3, the plurality of inner pins 4, the eccentric bearing 5, the bearing member 6, the eccentric shaft 7, the support body 8, etc. that are the components of the gear device 1 are made of stainless steel. , cast iron, carbon steel for mechanical structures, chromium molybdenum steel, phosphor bronze, or aluminum bronze. The metal referred to here includes metal that has been subjected to surface treatment such as nitriding treatment.

Further, in this basic configuration, an internal planetary gear device using trochoidal tooth profiles is illustrated as an example of the gear device 1. That is, the gear device 1 according to the present basic configuration includes an internal planetary gear 3 having a trochoidal curved tooth profile.

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

Furthermore, in this basic configuration, when the gear device 1 is used in the actuator 100, by applying a rotational force as an input to the eccentric shaft 7, rotation as an output is generated from the output shaft integrated with the inner ring 61 of the bearing member 6. power is extracted. That is, the gear device 1 operates using the rotation of the eccentric shaft 7 as input rotation and the rotation of the output shaft integrated with the inner ring 61 as output rotation. As a result, the gear device 1 can obtain an output rotation that is reduced at a relatively high reduction ratio with respect to the input rotation.

The drive source 101 is a power generation source such as a motor (electric motor). The power generated by the drive source 101 is transmitted to the eccentric shaft 7 in the gear device 1 . Specifically, the drive source 101 is connected to the eccentric shaft 7 via an input shaft, and the power generated by the drive source 101 is transmitted to the eccentric shaft 7 via the input shaft. Thereby, the drive source 101 can rotate the eccentric shaft 7.

Furthermore, in the gear device 1 according to this basic configuration, as shown in FIG. 3, the input side rotation axis Ax1 and the output side rotation axis Ax1 are on the same straight line. In other words, the input side rotation axis Ax1 and the output side rotation axis Ax1 are coaxial. Here, the input side rotation axis Ax1 is the rotation center of the eccentric shaft 7 to which input rotation is applied, and the output side rotation axis Ax1 is the rotation center of the inner ring 61 (and output shaft) that generates output rotation. . In other words, in the gear device 1, on the same axis, an output rotation that is reduced at a relatively high reduction ratio with respect to the input rotation is obtained.

The internal gear 2 is an annular component having internal teeth 21, as shown in FIG. In this basic configuration, the internal gear 2 has an annular shape in which at least the inner circumferential surface is a perfect circle in plan view. Internal teeth 21 are formed on the inner circumferential surface of the annular internal gear 2 along the circumferential direction of the internal gear 2 . The plurality of teeth constituting the internal teeth 21 all have the same shape, and are provided at equal pitches over the entire circumferential area of the internal peripheral surface of the internal gear 2. That is, the pitch circle of the internal teeth 21 becomes a perfect circle in plan view. The center of the pitch circle of the internal teeth 21 is on the rotation axis Ax1. Further, the internal gear 2 has a predetermined thickness in the direction of the rotation axis Ax1. The tooth traces of the internal teeth 21 are all parallel to the rotation axis Ax1. The dimension of the internal teeth 21 in the tooth trace direction is slightly smaller than the thickness direction of the internal gear 2.

Here, the internal gear 2 has an annular (circular) gear main body 22 and a plurality of external pins 23, as described above. The plurality of outer pins 23 are held on the inner circumferential surface 221 of the gear body 22 in a rotatable state, and constitute the inner teeth 21. In other words, the plurality of outer pins 23 each function as a plurality of teeth constituting the inner teeth 21. Specifically, as shown in FIG. 2, a plurality of inner circumferential grooves 223 are formed in the inner circumferential surface 221 of the gear body 22 in the entire circumferential direction. The plurality of inner circumferential grooves 223 all have the same shape and are provided at equal pitches. The plurality of inner circumferential grooves 223 are all parallel to the rotation axis Ax<b>1 and are formed over the entire length of the gear body 22 in the thickness direction. The plurality of outer pins 23 are combined with the gear body 22 so as to fit into the plurality of inner circumferential grooves 223. Each of the plurality of outer pins 23 is held in a rotatable state within the inner circumferential groove 223. Further, the gear body 22 is fixed to the case 10 (together with the outer ring 62). Therefore, a plurality of fixing holes 222 for fixing are formed in the gear body 22.

The planetary gear 3 is an annular component having external teeth 31, as shown in FIG. In this basic configuration, the planetary gear 3 has an annular shape in which at least the outer circumferential surface is a perfect circle in plan view. External teeth 31 are formed on the outer peripheral surface of the annular planetary gear 3 along the circumferential direction of the planetary gear 3. The plurality of teeth constituting the external teeth 31 all have the same shape, and are provided at equal pitches over the entire circumferential area of the outer peripheral surface of the planetary gear 3. That is, the pitch circle of the external teeth 31 becomes a perfect circle in plan view. The center C1 of the pitch circle of the external tooth 31 is located at a position shifted from the rotation axis Ax1 by a distance ΔL (see FIG. 4). Furthermore, the planetary 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 planetary gear 3 in the thickness direction. The tooth traces of the external teeth 31 are all parallel to the rotation axis Ax1. In the planetary gear 3, unlike the internal gear 2, the external teeth 31 are integrally formed with the main body of the planetary gear 3 from one metal member.

Here, an eccentric bearing 5 and an eccentric shaft 7 are combined with the planetary gear 3. That is, the planetary gear 3 is formed with a circular opening 33 . The opening 33 is a hole that passes through the planetary gear 3 in the thickness direction. In plan view, the center of the opening 33 and the center of the planetary gear 3 coincide, and the inner peripheral surface of the opening 33 (inner peripheral surface of the planetary gear 3) and the pitch circle of the external tooth 31 are concentric circles. . The eccentric bearing 5 is accommodated in the opening 33 of the planetary gear 3 . Further, by inserting the eccentric shaft 7 into the eccentric bearing 5 (the eccentric inner ring 51 thereof), the eccentric bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3. When the eccentric shaft 7 rotates with the planetary gear 3 combined with the eccentric bearing 5 and the eccentric shaft 7, the planetary gear 3 swings around the rotation axis Ax1.

The planetary gear 3 configured in this way is arranged inside the internal gear 2. In plan view, the planetary gear 3 is formed to be one size smaller than the internal gear 2, and the planetary gear 3 can swing inside the internal gear 2 when combined with the internal gear 2. Become. Here, external teeth 31 are formed on the outer peripheral surface of the planetary gear 3, and internal teeth 21 are formed on the inner peripheral surface of the internal gear 2. Therefore, when the planetary gear 3 is disposed inside the internal gear 2, the external teeth 31 and the internal teeth 21 face each other.

Furthermore, the pitch circle of the external teeth 31 is one size smaller than the pitch circle of the internal teeth 21. In a state where the planetary gear 3 is inscribed in the internal gear 2, the center C1 of the pitch circle of the external teeth 31 is a distance ΔL (see FIG. 4) from the center of the pitch circle of the internal teeth 21 (rotation axis Ax1). It's in a different position. Therefore, at least a portion of the external teeth 31 and the internal teeth 21 face each other with a gap therebetween, and the entire circumferential direction does not mesh with each other. However, since the planetary gear 3 swings (revolutions) around the rotation axis Ax1 inside the internal gear 2, the external teeth 31 and the internal teeth 21 partially mesh with each other. That is, as the planetary gear 3 swings around the rotation axis Ax1, as shown in FIG. It will interlock with some of your teeth. As a result, in the gear device 1, it becomes possible to mesh a portion of the external teeth 31 with a portion of the internal teeth 21.

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

Further, in this basic configuration, as an example, the thickness of the planetary gear 3 is smaller than the thickness of the gear body 22 in the internal gear 2. Furthermore, the dimension of the external tooth 31 in the tooth trace direction (direction parallel to the rotation axis Ax1) is smaller than the dimension of the internal tooth 21 in the tooth trace direction (direction parallel to the rotation axis Ax1). In other words, the external teeth 31 fall within the range of the tooth traces of the internal teeth 21 in the direction parallel to the rotation axis Ax1.

In this basic configuration, as described above, the rotation corresponding to the autorotation component of the planetary gear 3 is extracted as the rotation (output rotation) of the output shaft integrated with the inner ring 61 of the bearing member 6. Therefore, the planetary gear 3 is connected to the inner ring 61 by the plurality of inner pins 4. As shown in FIGS. 5A and 5B, the planetary gear 3 is formed with a plurality of loose fitting holes 32 into which the plurality of inner pins 4 are inserted. The same number of loose fitting holes 32 as the inner pins 4 are provided, and in this basic configuration, as an example, 18 loose fitting holes 32 and 18 inner pins 4 are provided. Each of the plurality of loose fitting holes 32 has a circular opening and is a hole that penetrates the planetary gear 3 along the thickness direction. A plurality of (here, 18) loose fitting holes 32 are arranged on a virtual circle concentric with the opening 33 at equal intervals in the circumferential direction.

The plurality of inner pins 4 are components that connect the planetary gear 3 and the inner ring 61 of the bearing member 6. Each of the plurality of inner pins 4 is formed into a cylindrical shape. The diameter and length of the plurality of inner pins 4 are common to the plurality of inner pins 4. The diameter of the inner pin 4 is one size smaller than the diameter of the loose fit hole 32. Thereby, the inner pin 4 is inserted into the loose fit hole 32 with a space (gap) secured between it and the inner peripheral surface 321 of the loose fit hole 32 (see FIG. 4).

The bearing member 6 has an outer ring 62 and an inner ring 61, and is a component for extracting the output of the gear device 1 as rotation of the inner ring 61 relative to the outer ring 62. The bearing member 6 includes, in addition to an outer ring 62 and an inner ring 61, a plurality of rolling elements 63 (see FIG. 3).

The outer ring 62 and the inner ring 61 are both annular parts, as shown in FIGS. 6A and 6B. Both the outer ring 62 and the inner ring 61 have an annular shape that is a perfect circle in plan view. The inner ring 61 is one size smaller than the outer ring 62 and is arranged inside the outer ring 62. Here, since the inner diameter of the outer ring 62 is larger than the outer diameter of the inner ring 61, a gap is created between the inner circumferential surface of the outer ring 62 and the outer circumferential surface of the inner ring 61.

The inner ring 61 has a plurality of holding holes 611 into which the plurality of inner pins 4 are respectively inserted. The same number of holding holes 611 as the inner pins 4 are provided, and in this basic configuration, as an example, 18 holding holes 611 are provided. As shown in FIGS. 6A and 6B, each of the plurality of holding holes 611 has a circular opening and is a hole that penetrates the inner ring 61 along the thickness direction. A plurality of (here, 18) holding holes 611 are arranged at equal intervals in the circumferential direction on a virtual circle concentric with the outer periphery of the inner ring 61. The diameter of the holding hole 611 is greater than or equal to the diameter of the inner pin 4 and smaller than the diameter of the loose fit hole 32.

Further, the inner ring 61 is integrated with the output shaft, and the rotation of the inner ring 61 is extracted as the rotation of the output shaft. Therefore, the inner ring 61 is formed with a plurality of output-side mounting holes 612 (see FIG. 2) for mounting the output shaft. In this basic configuration, the plurality of output-side mounting holes 612 are arranged on an imaginary circle that is inner than the plurality of holding holes 611 and concentric with the outer periphery of the inner ring 61.

The outer ring 62 is fixed to a fixed member such as the case 10 together with the gear body 22 of the internal gear 2. Therefore, a plurality of fixing holes 621 are formed in the outer ring 62. Specifically, as shown in FIG. 3, with the gear body 22 sandwiched between the outer ring 62 and the case 10, a fixing screw (bolt) is inserted through the through hole 621 and the fixing hole 222 of the gear body 22. ) 60 and is fixed to the case 10.

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

In this basic configuration, as an example, the bearing member 6 is a cross roller bearing. That is, the bearing member 6 has cylindrical rollers as the rolling elements 63. The axis of the cylindrical rolling element 63 has an inclination of 45 degrees with respect to a plane perpendicular to the rotation axis Ax<b>1 and is perpendicular to the outer periphery of the inner ring 61 . Furthermore, a pair of rolling elements 63 that are adjacent to each other in the circumferential direction of the inner ring 61 are arranged such that their axial directions are orthogonal to each other. The bearing member 6 made of such a cross-roller bearing easily receives loads in the radial direction, loads in the thrust direction (direction along the rotation axis Ax1), and bending force (bending moment load) with respect to the rotation axis Ax1. . Moreover, one bearing member 6 can withstand these three types of loads and ensure necessary rigidity.

The eccentric shaft 7 is a cylindrical component, as shown in FIGS. 7A and 7B. The eccentric shaft 7 has an axial center portion 71 and an eccentric portion 72. The shaft center portion 71 has a cylindrical shape with at least the outer circumferential surface being a perfect circle in plan view. The center (center axis) of the shaft center portion 71 coincides with the rotation axis Ax1. The eccentric portion 72 has a disc shape with at least the outer circumferential surface being a perfect circle in plan view. The center (central axis) of the eccentric portion 72 coincides with a center C1 shifted from the rotation axis Ax1. Here, the distance ΔL between the rotation axis Ax1 and the center C1 (see FIG. 7B) is the amount of eccentricity of the eccentric portion 72 with respect to the shaft center portion 71. The eccentric portion 72 has a flange shape that protrudes from the outer peripheral surface of the shaft center portion 71 over the entire circumference at the central portion of the shaft center portion 71 in the longitudinal direction (axial direction). According to the configuration described above, in the eccentric shaft 7, the eccentric portion 72 moves eccentrically as the shaft center portion 71 rotates (rotates) about the rotation axis Ax1.

In this basic configuration, the shaft center portion 71 and the eccentric portion 72 are integrally formed of one metal member, thereby realizing a seamless eccentric shaft 7. The eccentric shaft 7 having such a shape is combined with the eccentric bearing 5 and the planetary gear 3. Therefore, when the eccentric shaft 7 rotates with the planetary gear 3 combined with the eccentric bearing 5 and the eccentric shaft 7, the planetary gear 3 swings around the rotation axis Ax1.

Furthermore, the eccentric shaft 7 has a through hole 73 that penetrates the shaft center portion 71 in the axial direction (longitudinal direction). The through hole 73 is opened in a circular shape on both end surfaces of the shaft center portion 71 in the axial direction. The center (central axis) of the through hole 73 coincides with the rotation axis Ax1. For example, cables such as a power line and a signal line can be passed through the through hole 73.

Further, in this basic configuration, a rotational force as an input is applied from the drive source 101 to the eccentric shaft 7. Therefore, a plurality of input-side mounting holes 74 (see FIGS. 7A and 7B) are formed in the eccentric shaft 7 for mounting an input shaft connected to the drive source 101. In this basic configuration, the plurality of input-side mounting holes 74 are arranged around the through hole 73 on one end surface in the axial direction of the shaft center portion 71 on an imaginary circle concentric with the through hole 73.

The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51, absorbs the rotation component of the rotation of the eccentric shaft 7, and absorbs the rotation of the eccentric shaft 7 excluding the rotation component of the eccentric shaft 7, that is, the eccentric shaft 7. This is a component for transmitting only the oscillation component (revolution component) of the shaft 7 to the planetary gear 3. The eccentric bearing 5 includes a plurality of rolling elements 53 (see FIG. 3) in addition to an eccentric outer ring 52 and an eccentric inner ring 51.

Both the eccentric outer ring 52 and the eccentric inner ring 51 are annular parts. The eccentric outer ring 52 and the eccentric inner ring 51 both have an annular shape that is a perfect circle in plan view. The eccentric inner ring 51 is one size smaller than the eccentric outer ring 52 and is arranged inside the eccentric outer ring 52. Here, since the inner diameter of the eccentric outer ring 52 is larger than the outer diameter of the eccentric inner ring 51, a gap is created between the inner circumferential surface of the eccentric outer ring 52 and the outer circumferential surface of the eccentric inner ring 51.

The plurality of rolling elements 53 are arranged in a gap between the eccentric outer ring 52 and the eccentric inner ring 51. The plurality of rolling elements 53 are arranged side by side in the circumferential direction of the eccentric outer ring 52. The plurality of rolling elements 53 are all metal parts having the same shape, and are provided at equal pitches over the entire circumferential area of the eccentric outer ring 52. In this basic configuration, as an example, the eccentric bearing 5 is a deep groove ball bearing using balls as the rolling elements 53.

Here, the inner diameter of the eccentric inner ring 51 matches the outer diameter of the eccentric portion 72 of the eccentric shaft 7. The eccentric bearing 5 is combined with the eccentric shaft 7 with the eccentric portion 72 of the eccentric shaft 7 inserted into the eccentric inner ring 51. Further, the outer diameter of the eccentric outer ring 52 matches the inner diameter (diameter) of the opening 33 in the planetary gear 3. The eccentric bearing 5 is combined with the planetary gear 3 with the eccentric outer ring 52 fitted into the opening 33 of the planetary gear 3. In other words, the opening 33 of the planetary gear 3 accommodates the eccentric bearing 5 mounted on the eccentric portion 72 of the eccentric shaft 7 .

Further, in this basic configuration, as an example, the dimension of the eccentric inner ring 51 in the eccentric body bearing 5 in the width direction (direction parallel to the rotation axis Ax1) is approximately the same as the thickness of the eccentric portion 72 of the eccentric shaft 7. The dimension of the eccentric outer ring 52 in the width direction (direction parallel to the rotation axis Ax1) is slightly smaller than the dimension of the eccentric inner ring 51 in the width direction. Furthermore, the dimension of the eccentric outer ring 52 in the width direction is larger than the thickness of the planetary gear 3. Therefore, the planetary gear 3 falls within the range of the eccentric bearing 5 in the direction parallel to the rotation axis Ax1. On the other hand, the dimension of the eccentric outer ring 52 in the width direction is smaller than the dimension of the internal teeth 21 in the tooth trace direction (direction parallel to the rotation axis Ax1). Therefore, the eccentric bearing 5 falls within the range of the internal gear 2 in the direction parallel to the rotation axis Ax1.

When the eccentric shaft 7 rotates with the eccentric bearing 5 and the eccentric shaft 7 combined with the planetary gear 3, the eccentric shaft 7 rotates in the eccentric bearing 5 around the rotation axis Ax1 which is offset from the center C1 of the eccentric inner ring 51. The wheel 51 rotates (eccentric movement). At this time, the rotation component of the eccentric shaft 7 is absorbed by the eccentric bearing 5. Therefore, only the rotation of the eccentric shaft 7 excluding the rotation component of the eccentric shaft 7, that is, the swing component (revolution component) of the eccentric shaft 7 is transmitted to the planetary gear 3 by the eccentric bearing 5. Therefore, when the eccentric shaft 7 rotates in a state in which the eccentric body bearing 5 and the eccentric shaft 7 are combined with the planetary gear 3, the planetary gear 3 swings around the rotation axis Ax1.

The support body 8 is a component that is formed in an annular shape and supports the plurality of inner pins 4, as shown in FIGS. 8A and 8B. The support body 8 has a plurality of support holes 82 into which the plurality of inner pins 4 are respectively inserted. The same number of support holes 82 as the inner pins 4 are provided, and in this basic configuration, as an example, 18 support holes 82 are provided. As shown in FIGS. 8A and 8B, each of the plurality of support holes 82 has a circular opening and is a hole that penetrates the support body 8 along 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 circumferential surface 81 of the support body 8. The diameter of the support hole 82 is greater than or equal to the diameter of the inner pin 4 and smaller than the diameter of the loose fit hole 32. In this basic configuration, as an example, the diameter of the support hole 82 is equal to the diameter of the holding hole 611 formed in the inner ring 61.

As shown in FIG. 3, the support body 8 is arranged so as to face the planetary gear 3 from one side (input side) of the rotation axis Ax1. By inserting the plurality of inner pins 4 into the plurality of support holes 82, the support body 8 functions to bundle the plurality of inner pins 4. Furthermore, the position of the support body 8 is regulated by bringing the outer circumferential surface 81 into contact with the plurality of outer pins 23 . As a result, the support body 8 is centered by the plurality of outer 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 outer pins 23. be exposed. The support 8 will be described in detail in the section "(3.3) Support".

The first bearing 91 and the second bearing 92 are each mounted on the shaft center portion 71 of the eccentric shaft 7. Specifically, as shown in FIG. 3, the first bearing 91 and the second bearing 92 are arranged on both sides of the eccentric part 72 in the shaft center part 71 so as to sandwich the eccentric part 72 in a direction parallel to the rotation axis Ax1. It will be installed. 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 when viewed from the eccentric portion 72. The first bearing 91 rotatably holds the eccentric shaft 7 relative to the case 10. The second bearing 92 rotatably holds the eccentric shaft 7 relative to the inner ring 61 of the bearing member 6. Thereby, the axial center portion 71 of the eccentric shaft 7 is rotatably held at two locations on both sides of the eccentric portion 72 in a direction parallel to the rotation axis Ax1.

The case 10 has a cylindrical shape and has a flange portion 11 on the output side of the rotation axis Ax1. A plurality of installation holes 111 are formed in the flange portion 11 for fixing the case 10 itself. Further, a bearing hole 12 is formed in the output side end surface of the rotating shaft Ax1 in the case 10. The bearing hole 12 has a circular opening. By fitting the first bearing 91 into the bearing hole 12, the first bearing 91 is attached to the case 10.

Further, a plurality of screw holes 13 are formed around the bearing hole 12 on the output side end surface of the rotating shaft Ax1 in the case 10. The plurality of screw holes 13 are used to fix the gear main body 22 of the internal gear 2 and the outer ring 62 of the bearing member 6 to the case 10. Specifically, the fixing screw 60 passes through the through hole 621 of the outer ring 62 and the fixing hole 222 of the gear body 22 and is tightened into the screw hole 13, thereby fixing the gear body 22 and the outer ring 62 to the case 10. be done.

Further, the gear device 1 according to the present basic configuration further includes a plurality of oil seals 14, 15, 16, etc., as shown in FIG. The oil seal 14 is attached to the end of the eccentric shaft 7 on the input side of the rotating shaft Ax1, and closes the gap between the case 10 and the eccentric shaft 7 (axis center portion 71). The oil seal 15 is attached to the end of the eccentric shaft 7 on the output side of the rotating shaft Ax1, and closes the gap between the inner ring 61 and the eccentric shaft 7 (axis center portion 71). The oil seal 16 is attached to the end surface of the bearing member 6 on the output side of the rotating shaft Ax1, and closes the gap between the inner ring 61 and the outer ring 62. The space sealed by these plurality of oil seals 14, 15, and 16 constitutes a lubricant holding space 17 (see FIG. 9). The lubricant holding space 17 includes a space between the inner ring 61 and the outer ring 62 of the bearing member 6. Further, inside the lubricant holding space 17, a plurality of outer pins 23, a planetary gear 3, an eccentric bearing 5, a support body 8, a first bearing 91, a second bearing 92, etc. are housed.

A lubricant is injected into the lubricant holding space 17. The lubricant is a liquid and can flow within the lubricant holding space 17. Therefore, when the gear device 1 is used, for example, lubricant enters the meshing region between the internal teeth 21 made up of the plurality of external pins 23 and the external teeth 31 of the planetary gear 3. "Liquid" as used in the present disclosure includes liquid or gel-like substances. The term "gel-like" used herein means a state having properties intermediate between a liquid and a solid, and includes a colloid state consisting of two phases, a liquid phase and a solid phase. For example, there are states called gels or sol, such as emulsion where the dispersion medium is a liquid phase and the dispersoid is a liquid phase, and suspension where the dispersoid is a solid phase. Included in "gel-like". Furthermore, a state in which the dispersion medium is in a solid phase and the dispersoid is in a liquid phase is also included in the term "gel-like." In this basic configuration, as an example, the lubricant is liquid lubricating oil (oil).

In the gear device 1 configured as described above, a rotational force as an input is applied to the eccentric shaft 7, and the eccentric shaft 7 rotates around the rotation axis Ax1, so that the planetary gear 3 swings around the rotation axis Ax1. (revolution). At this time, the planetary gear 3 is inscribed with the internal gear 2 inside the internal gear 2, and swings with a part of the external tooth 31 meshing with a part of the internal tooth 21, so that the internal gear 21 and the external teeth 31 move in the circumferential direction of the internal gear 2. As a result, relative rotation occurs between the planetary gear 3 and the internal gear 2 according to the difference in the number of teeth between the two gears (the internal gear 2 and the planetary gear 3). The rotation (rotation component) of the planetary gear 3, excluding the oscillation component (revolution component) of the planetary gear 3, is transmitted to the inner ring 61 of the bearing member 6 by the plurality of inner pins 4. As a result, from the output shaft integrated with the inner ring 61, a rotational output is obtained that is reduced in speed at a relatively high reduction ratio in accordance with the difference in the number of teeth between both gears.

By the way, in the gear device 1 according to the present basic configuration, as described above, the difference in the number of teeth between the internal gear 2 and the planetary gear 3 defines the reduction ratio of the output rotation to the input rotation in the gear device 1. become. That is, when the number of teeth of the internal gear 2 is "V1" and the number of teeth of the planetary gear 3 is "V2", the reduction ratio R1 is expressed by the following formula 0.

R1=V2/(V1-V2) (Formula 0)
In short, the smaller the difference in the number of teeth (V1-V2) between the internal gear 2 and the planetary gear 3, the larger the reduction ratio R1 becomes. As an example, since the number of teeth V1 of the internal gear 2 is "52", the number of teeth V2 of the planetary gear 3 is "51", and the difference in the number of teeth (V1-V2) is "1", from the above formula 0, The reduction ratio R1 becomes "51". In this case, when the eccentric shaft 7 rotates once (360 degrees) clockwise around the rotation axis Ax1 when viewed from the input side of the rotation axis Ax1, the inner ring 61 has a tooth difference of "1" around the rotation axis Ax1. (that is, about 7.06 degrees) counterclockwise.

According to the gear device 1 according to the present basic configuration, such a high reduction ratio R1 can be achieved by a combination of one-stage gears (the internal gear 2 and the planetary gears 3).

Further, the gear device 1 only needs to include at least an internal gear 2, a planetary gear 3, a plurality of internal pins 4, a bearing member 6, and a support body 8. For example, a spline bushing or the like may be provided. It may further be provided as a component.

By the way, when the input rotation on the high-speed rotation side is accompanied by eccentric movement, as in the gear device 1 according to the present basic configuration, if the weight of the rotating body that rotates at high speed is not balanced, it may lead to vibration etc. Therefore, a counterweight or the like may be used to balance the weight. That is, since the rotating body consisting of at least one of the eccentric inner ring 51 and a member (eccentric shaft 7) that rotates together with the eccentric inner ring 51 moves eccentrically at high speed, it is possible to balance the weight of the rotating body with respect to the rotation axis Ax1. preferable. In this basic configuration, as shown in FIGS. 3 and 4, a gap 75 is provided in a part of the eccentric portion 72 of the eccentric shaft 7 to balance the weight of the rotating body with respect to the rotating shaft Ax1.

In short, in this basic configuration, rather than adding a counterweight or the like, the weight is reduced by thinning out a part of the rotating body (here, the eccentric shaft 7), thereby improving the weight balance of the rotating body with respect to the rotating shaft Ax1. I'm taking it. That is, the gear device 1 according to the present basic configuration includes an eccentric bearing 5 that is accommodated in an opening 33 formed in the planetary gear 3 and causes the planetary gear 3 to swing. The eccentric bearing 5 has an eccentric outer ring 52 and an eccentric inner ring 51 disposed inside the eccentric outer ring 52. A rotating body including at least one of the eccentric inner ring 51 and a member that rotates together with the eccentric inner ring 51 has a gap 75 in a part of the eccentric outer ring 52 on the center C1 side when viewed from the rotation axis Ax1 of the eccentric inner ring 51. . In this basic configuration, the eccentric shaft 7 is a "member that rotates together with the eccentric inner ring 51" and corresponds to a "rotating body." Therefore, the gap 75 formed in the eccentric portion 72 of the eccentric shaft 7 corresponds to the gap 75 of the rotating body. As shown in FIGS. 3 and 4, this gap 75 is located on the center C1 side when viewed from the rotation axis Ax1, so that the weight balance of the eccentric shaft 7 is made evenly closer to the rotation axis Ax1 in the circumferential direction. act.

More specifically, the void 75 includes a recess formed in the inner circumferential surface of the through hole 73 that passes through the rotating body along the rotation axis Ax1 of the eccentric inner ring 51. That is, in this basic configuration, since the rotating body is the eccentric shaft 7, the recess formed in 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 recess formed in the inner circumferential surface of the through hole 73 as the void 75, it becomes possible to balance the weight of the rotating body without changing the appearance.

(3.2) Rotation structure of inner pin Next, the rotation structure of the inner pin 4 of the gear device 1 according to the present basic configuration will be described in more detail with reference to FIG. 9. FIG. 9 is an enlarged view of region Z1 in FIG.

First, as a premise, the plurality of inner pins 4 are components that connect the planetary gear 3 and the inner ring 61 of the bearing member 6, as described above. Specifically, one end of the inner pin 4 in the longitudinal direction (in this basic configuration, the end on the input side of the rotating shaft Ax1) is inserted into the loose fitting hole 32 of the planetary gear 3, and the end of the inner pin 4 in the longitudinal direction The other end (in this basic configuration, the end on the output side of the rotating shaft Ax1) is inserted into the holding hole 611 of the inner ring 61.

Here, since the diameter of the inner pin 4 is one size smaller than the diameter of the loose fit hole 32, a gap is secured between the inner pin 4 and the inner peripheral surface 321 of the loose fit hole 32, and the inner pin 4 is , is movable within the loose fit hole 32, that is, movable relative to the center of the loose fit hole 32. On the other hand, the diameter of the holding hole 611 is larger than the diameter of the inner pin 4 but smaller than the diameter of the loose fit hole 32. In this basic configuration, the diameter of the holding 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, movement of the inner pin 4 within the holding hole 611 is restricted, that is, movement relative to the center of the holding hole 611 is prohibited. Therefore, the inner pin 4 is held in a state in which it can revolve within the loose fitting hole 32 in the planetary gear 3, and is held in a state in which it cannot revolve in the holding hole 611 with respect to the inner ring 61. As a result, the oscillation component of the planetary gear 3, that is, the revolution component of the planetary gear 3, is absorbed by the loose fit between the loose fitting hole 32 and the inner pin 4, and the inner ring 61 is provided with a plurality of inner pins 4, so that the planetary gear The rotation (rotation component) of the planetary gear 3 excluding the oscillation component (revolution component) of 3 is transmitted.

By the way, in this basic configuration, since the diameter of the inner pin 4 is slightly larger than the holding hole 611, the inner pin 4 is prohibited from rotating within the holding hole 611 when it is inserted into the holding hole 611. However, rotation within the holding hole 611 is possible. That is, even when the inner pin 4 is inserted into the holding hole 611, it is not press-fitted into the holding hole 611, so that it can rotate within the holding hole 611. In this way, in the gear device 1 according to the present basic configuration, each of the plurality of inner pins 4 is held in the inner ring 61 in a rotatable state, so that when the inner pin 4 revolves within the loose fitting hole 32, , the inner pin 4 itself is rotatable.

In short, in this basic configuration, the inner pin 4 is held with respect to the planetary gear 3 in a state where it can both revolve and rotate within the loose fitting hole 32, and with respect to the inner ring 61, it is held within the holding hole 611. It is maintained in a state where only rotation is possible at . In other words, the plurality of inner pins 4 can rotate (revolution) around the rotation axis Ax1 in a state in which each of the inner pins 4 is not restrained in its rotation (a state in which it can rotate), and can also revolve within the plurality of loose fitting holes 32. It is. Therefore, when transmitting the rotation (autorotation component) of the planetary gear 3 to the inner ring 61 using the plurality of inner pins 4, the inner pins 4 revolve and rotate within the loose fitting hole 32 while rotating within the holding hole 611. It can rotate. Therefore, when the inner pin 4 revolves within the loose fit hole 32, the inner pin 4 is in a state where it can rotate, so it rolls against the inner circumferential surface 321 of the loose fit hole 32. In other words, since the inner pin 4 revolves within the loose fit hole 32 so as to roll on the inner circumferential surface 321 of the loose fit hole 32, the inner pin 4 rotates on the inner circumferential surface 321 of the loose fit hole 32 and Loss due to frictional resistance is less likely to occur.

In this manner, in the configuration according to the present basic configuration, loss due to frictional resistance between the inner circumferential surface 321 of the loose fitting hole 32 and the inner pin 4 is less likely to occur in the first place, so the inner roller can be omitted. Therefore, in this basic configuration, each of the plurality of inner pins 4 is configured to directly contact the inner circumferential surface 321 of the loose fit hole 32. That is, in this basic configuration, the inner pin 4 with no inner roller attached is inserted into the loose fit hole 32, and the inner pin 4 directly contacts the inner circumferential surface 321 of the loose fit hole 32. . As a result, the inner roller can be omitted and the diameter of the loose fitting hole 32 can be kept relatively small, so the planetary gear 3 can be made smaller (particularly smaller in diameter), and the gear device 1 as a whole can be made smaller. It becomes easier to plan. If the dimensions of the planetary gear 3 are to be constant, compared to the first related technology described above, for example, the number of inner pins 4 may be increased to smooth the transmission of rotation, or the inner pins 4 may be made thicker. It is also possible to improve the strength. Furthermore, the number of parts can be reduced by the inner roller, leading to lower costs of the gear device 1.

Moreover, in the gear device 1 according to the present basic configuration, 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. That is, as shown in FIG. 9, at least a portion of the inner pin 4 is arranged at the same position as the bearing member 6 in the direction parallel to the rotation axis Ax1. In other words, at least a portion of the inner pin 4 is located between both end surfaces of the bearing member 6 in the 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 inside the outer ring 62 of the bearing member 6. In this basic configuration, the end 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 the direction parallel to the rotation axis Ax1. In short, since the end of the inner pin 4 on the output side of the rotating shaft Ax1 is inserted into the holding hole 611 formed in the inner ring 61 of the bearing member 6, at least the end thereof is attached to the shaft of the bearing member 6. It will be placed at the same position as the bearing member 6 in the direction.

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, so that the dimension of the gear device 1 in the direction parallel to the rotation axis Ax1 is reduced. can be kept small. That is, compared to a configuration in which the bearing member 6 and the inner pin 4 are lined up (opposed) in the axial direction of the bearing member 6, in the gear device 1 according to this basic configuration, the gear device 1 in the direction parallel to the rotation axis Ax1 The dimensions of the gear device 1 can be reduced, contributing to further miniaturization (thinner thickness) of the gear device 1.

Here, the opening surface of the holding hole 611 on the output side of the rotating shaft Ax1 is closed by, for example, an output shaft that is integrated with the inner ring 61. As a result, the movement of the inner pin 4 toward the output side of the rotating shaft Ax1 (the right side in FIG. 9) is regulated by the output shaft integrated with the inner ring 61 or the like.

Further, in this basic configuration, the following configuration is adopted so that the inner pin 4 rotates smoothly with respect to the inner ring 61. That is, by interposing a lubricant (lubricating oil) between the inner peripheral surface of the holding hole 611 formed in the inner ring 61 and the inner pin 4, the rotation of the inner pin 4 is made smooth. In particular, in this basic configuration, since the lubricant holding space 17 into which lubricant is injected exists between the inner ring 61 and the outer ring 62, the lubricant in the lubricant holding space 17 is used to hold the inner pin 4. Try to make rotation smoother.

In this basic configuration, as shown in FIG. 9, the inner ring 61 has a plurality of holding holes 611 into which the plurality of inner pins 4 are respectively inserted, and a plurality of connection paths 64. The plurality of connecting passages 64 connect the lubricant holding space 17 between the inner ring 61 and the outer ring 62 and the plurality of holding holes 611. Specifically, a connecting path 64 is formed in the inner ring 61 and extends in the radial direction from a portion of the inner circumferential surface of the holding hole 611 that corresponds to the rolling element 63 . The connecting path 64 is a hole that penetrates between the bottom surface of a recess (groove) that accommodates the rolling element 63 on the surface of the inner ring 61 facing the outer ring 62 and the inner circumferential surface of the holding hole 611 . In other words, the opening surface of the connecting path 64 on the lubricant holding space 17 side is arranged at a position facing (opposing) the rolling elements 63 of the bearing member 6. The lubricant holding space 17 and the holding hole 611 are spatially connected through such a connecting path 64.

According to the above-described configuration, the lubricant holding space 17 and the holding hole 611 are connected through the connecting path 64, so that the lubricant in the lubricant holding space 17 is supplied to the holding hole 611 through the connecting path 64. become. In other words, when the bearing member 6 operates and the rolling element 63 rotates, the rolling element 63 functions as a pump and can send the lubricant in the lubricant holding space 17 to the holding hole 611 via the connecting path 64. It is. In particular, since the opening surface of the connecting path 64 on the lubricant holding space 17 side is located at a position facing (opposing) the rolling elements 63 of the bearing member 6, the rolling elements 63 function efficiently as a pump when the rolling elements 63 rotate. It acts in a certain way. As a result, a lubricant is present between the inner circumferential surface of the holding hole 611 and the inner pin 4, and smooth rotation of the inner pin 4 with respect to the inner ring 61 can be achieved.

(3.3) Support Next, the structure of the support 8 of the gear device 1 according to the present basic structure will be described in more detail with reference to FIG. 10. FIG. 10 is a sectional view taken along the line B1-B1 in FIG. However, in FIG. 10, hatching is omitted for parts other than the support body 8 even in cross sections. Further, in FIG. 10, only the internal gear 2 and the support body 8 are illustrated, and illustration of other parts (inner pin 4, etc.) is omitted. Furthermore, in FIG. 10, illustration of the inner circumferential surface 221 of the gear body 22 is omitted.

First, as a premise, the support body 8 is a component that supports the plurality of inner pins 4, as described above. That is, the support body 8 distributes the load applied to the plurality of inner pins 4 when transmitting the rotation (autorotation component) of the planetary gear 3 to the inner ring 61 by bundling the plurality of inner pins 4 together. Specifically, it has a plurality of support holes 82 into which the plurality of inner pins 4 are respectively inserted. In this basic configuration, as an example, the diameter of the support hole 82 is equal to the diameter of the holding hole 611 formed in the inner ring 61. Therefore, the support body 8 supports the plurality of inner pins 4 in a state where each of the plurality of inner pins 4 is rotatable. That is, each of the plurality of inner pins 4 is held in a rotatable state with respect to both the inner ring 61 of the bearing member 6 and the support body 8.

In this way, the support body 8 positions the plurality of inner pins 4 relative to the support body 8 in both the circumferential direction and the radial direction. That is, by being inserted into the support hole 82 of the support body 8, the inner pin 4 is restricted from moving in all directions within a plane perpendicular to the rotation axis Ax1. Therefore, the inner pin 4 is positioned on the support body 8 not only in the circumferential direction but also in the radial direction.

Here, the support body 8 has an annular shape in which at least the outer circumferential surface 81 is a perfect circle in plan view. The position of the support body 8 is regulated by bringing the outer circumferential surface 81 into contact with the plurality of external pins 23 of the internal gear 2 . Since the plurality of external pins 23 constitute the internal teeth 21 of the internal gear 2, in other words, the position of the support body 8 is regulated by bringing the outer circumferential surface 81 into contact with the internal teeth 21. Here, the diameter of the outer circumferential surface 81 of the support body 8 is the same as the diameter of a virtual circle (tip circle) passing through the tips of the internal teeth 21 in the internal gear 2 . Therefore, all of the plurality of outer pins 23 contact the outer circumferential surface 81 of the support body 8. Therefore, when the support body 8 is positionally regulated by the plurality of external pins 23, the center of the support body 8 is positionally regulated so as to overlap with the center of the internal gear 2 (rotation axis Ax1). Thereby, the support body 8 is centered, and as a result, the plurality of inner pins 4 supported by the support body 8 are also centered by the plurality of outer pins 23.

Further, the plurality of inner pins 4 transmit the rotation (rotation component) of the planetary gear 3 to the inner ring 61 by rotating (revolving) around the rotation axis Ax1. Therefore, the support body 8 that supports 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, since the support body 8 is centered by the plurality of outer pins 23, the support body 8 rotates smoothly while the center of the support body 8 is maintained on the rotation axis Ax1. Moreover, since the support body 8 rotates with its outer peripheral surface 81 in contact with the plurality of outer pins 23, each of the plurality of outer pins 23 rotates (rotates) as the support body 8 rotates. Therefore, the support body 8 constitutes a needle bearing (needle roller bearing) together with the internal gear 2, and rotates smoothly.

That is, the outer circumferential surface 81 of the support body 8 rotates together with the plurality of inner pins 4 relative to the gear body 22 while in contact with the plurality of outer pins 23 . Therefore, if the gear main body 22 of the internal gear 2 is regarded as an "outer ring" and the support body 8 is considered as an "inner ring", the plurality of outer pins 23 interposed between the two function as "rolling elements (rollers)". In this way, the support body 8 constitutes a needle bearing together with the internal gear 2 (the gear main body 22 and the plurality of external pins 23), and smooth rotation is possible.

Further, since the support body 8 and the gear body 22 sandwich the plurality of outer pins 23, the support body 8 suppresses movement of the outer pins 23 in a direction away from the inner circumferential surface 221 of the gear body 22. It also functions as a "stopper". In other words, the plurality of outer pins 23 are sandwiched between the outer peripheral surface 81 of the support body 8 and the inner peripheral surface 221 of the gear main body 22, and lifting from the inner peripheral surface 221 of the gear main body 22 is suppressed. . In short, in this basic configuration, each of the plurality of outer pins 23 is restricted from moving away from the gear body 22 by contacting the outer circumferential surface 81 of the support body 8.

By the way, in this basic configuration, as shown in FIG. 9, the support body 8 is located on the opposite side of the inner ring 61 of the bearing member 6 with the planetary gear 3 interposed therebetween. That is, the support body 8, the planetary gear 3, and the inner ring 61 are arranged side by side in a direction parallel to the rotation axis Ax1. In this basic configuration, as an example, the support body 8 is located on the input side of the rotating shaft Ax1 when viewed from the planetary gear 3, and the inner ring 61 is located on the output side of the rotating shaft Ax1 when viewed from the planetary gear 3. 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 center part of the inner pin 4 in the longitudinal direction is loosely fitted into the planetary gear 3. It is inserted into the hole 32. In short, the gear device 1 according to the present basic configuration includes an outer ring 62 and an inner ring 61 disposed inside the outer ring 62, and a bearing member 6 in which the inner ring 61 is rotatably supported relative to the outer ring 62. We are prepared. The gear body 22 is then fixed to the outer ring 62. Here, the planetary gear 3 is located between the support 8 and the inner ring 61 in the axial direction of the support 8.

According to this configuration, the support body 8 and the inner ring 61 support both ends of the inner pin 4 in the longitudinal direction, so that the inner pin 4 is less likely to tilt. In particular, it becomes easier to receive the bending force (bending moment load) applied to the plurality of inner pins 4 with respect to the rotation axis Ax1. Further, in this basic configuration, the support body 8 is sandwiched between the planetary gear 3 and the case 10 in a direction parallel to the rotation axis Ax1. As a result, movement of the support body 8 toward the input side (left side in FIG. 9) of the rotation axis Ax1 is restricted by the case 10. Regarding the inner pin 4 that penetrates the support hole 82 of the support body 8 and projects from the support body 8 toward the input side of the rotation axis Ax1, movement toward the input side of the rotation axis Ax1 (left side in FIG. 9) is also caused by the case 10. It is regulated by

In this basic configuration, the support body 8 and the inner ring 61 further contact both ends of the plurality of outer pins 23. That is, as shown in FIG. 9, the support body 8 contacts one end (the end on the input side of the rotation axis Ax1) of the outer pin 23 in the longitudinal direction (direction parallel to the rotation axis Ax1). The inner ring 61 contacts the other end (end on the output side of the rotation axis Ax1) of the outer pin 23 in the longitudinal direction (direction parallel to the rotation axis Ax1). According to this configuration, the support body 8 and the inner ring 61 are centered at both ends of the outer pin 23 in the longitudinal direction, so that the inner pin 4 is less likely to tilt. In particular, it becomes easier to receive the bending force (bending moment load) applied to the plurality of inner pins 4 with respect to the rotation axis Ax1.

Further, the plurality of outer pins 23 have a length equal to or 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 falls within the range of the tooth traces of the internal teeth 21. As a result, the outer circumferential surface 81 of the support body 8 comes into contact with the plurality of outer pins 23 over the entire length of the inner teeth 21 in the tooth trace direction (direction parallel to the rotation axis Ax1). Therefore, defects such as "uneven wear" in which the outer circumferential surface 81 of the support body 8 is partially worn out are less likely to occur.

Further, in this basic configuration, the outer peripheral surface 81 of the support 8 has a smaller surface roughness than one surface adjacent to the outer peripheral surface 81 of the support 8. That is, the surface roughness of the outer circumferential surface 81 is smaller than that of both end surfaces of the support body 8 in the axial direction (thickness direction). "Surface roughness" as used in the present disclosure means the degree of roughness of the surface of an object, and the smaller the value, the smaller (fewer) the unevenness of the surface and the smoother it is. In this basic configuration, as an example, the surface roughness is assumed to be an arithmetic mean roughness (Ra). For example, by processing such as polishing, the surface roughness of the outer circumferential surface 81 is made smaller than that of the other surfaces of the support body 8 . With this configuration, the support body 8 can rotate more smoothly.

Further, in this basic configuration, the hardness of the outer circumferential surface 81 of the support body 8 is lower than the circumferential surfaces of the plurality of outer pins 23 and higher than the inner circumferential surface 221 of the gear body 22. “Hardness” in the present disclosure refers to the degree of hardness of an object, and the hardness of a metal is expressed, for example, by the size of a depression formed by pressing a steel ball with a certain pressure. Specifically, examples of metal hardness include Rockwell hardness (HRC), Brinell hardness (HB), Vickers hardness (HV), and Shore hardness (Hs). Examples of means for increasing (hardening) the hardness of metal parts include alloying or heat treatment. In this basic configuration, for example, the hardness of the outer circumferential surface 81 of the support body 8 is increased by treatment such as carburizing and quenching. With this configuration, abrasion powder and the like are not likely to be generated even when the support body 8 rotates, and it is easy to maintain smooth rotation of the support body 8 over a long period of time.

(4) Application example Next, an application example of the gear device 1 and actuator 100 according to the present basic configuration will be described.

The gear device 1 and actuator 100 according to the present basic configuration are applied to a robot such as a horizontal multi-joint robot, a so-called SCARA (Selective Compliance Assembly Robot Arm) type robot, for example.

Furthermore, the application examples of the gear device 1 and the actuator 100 according to the present basic configuration are not limited to the above-mentioned horizontal articulated robots, but also to industrial robots other than horizontal articulated robots, or non-industrial robots, etc. There may be. Examples of industrial robots other than horizontal articulated robots include vertical articulated robots and parallel link robots. Examples of non-industrial robots include household robots, nursing care robots, and medical robots.

(Embodiment 1)
<Summary>
As shown in FIGS. 11 to 13, the internally meshing planetary gear device 1A (hereinafter also simply referred to as "gear device 1A") according to the present embodiment is an eccentric oscillating type internally meshing gear device called a distribution type. It differs from the gear device 1 according to the basic configuration in that it is a planetary gear device. Hereinafter, configurations similar to the basic configuration will be given the same reference numerals and descriptions will be omitted as appropriate. FIG. 11 is a perspective view showing a schematic configuration of the gear device 1A. FIG. 12 is a schematic exploded perspective view of the gear device 1A viewed from the input side of the rotation axis Ax1. FIG. 13 is a schematic cross-sectional view of the gear device 1A.

As shown in FIGS. 11 to 13, the gear device 1A according to this embodiment has a plurality of (three in this embodiment) arranged at positions offset from the axis (rotation axis Ax1) of the internal gear 2. Eccentric shafts (crankshafts) 7A, 7B, and 7C are provided. Furthermore, the gear device 1A includes an input shaft 500 centered on the rotation axis Ax1, which is arranged on the axis (rotation axis Ax1) of the internal gear 2, and an input gear 501 formed integrally with the input shaft 500. , is equipped with. Crankshaft gears 502A, 502B, and 502C are spline-coupled to the plurality of eccentric shafts 7A, 7B, and 7C, respectively. These plurality (three in this embodiment) of crankshaft gears 502A, 502B, and 502C are arranged so as to mesh with the input gear 501. Therefore, when the input shaft 500 is driven, the gear device 1A causes the input gear 501 to synchronously drive the eccentric shafts 7A, 7B, and 7C, thereby causing the internal gear 2 to rotate while swinging the planetary gear 3. It is interlocked.

Further, the gear device 1A according to the present embodiment includes a plurality of planetary gears 3. Specifically, the gear device 1A includes two planetary gears 3, a first planetary gear 301 and a second planetary gear 302. The two planetary gears 3 are arranged to face each other in a direction parallel to the rotation axis Ax1. That is, the planetary gear 3 includes a first planetary gear 301 and a second planetary gear 302 that are arranged in a direction parallel to the rotation axis Ax1. The shapes of the first planetary gear 301 and the second planetary gear 302 are the same.

These two planetary gears 3 (first planetary gear 301 and second planetary gear 302) are arranged with a phase difference of 180 degrees around the rotation axis Ax1. In the example of FIG. 13, of the first planetary gear 301 and the second planetary gear 302, the center C1 of the first planetary gear 301 located on the input side of the rotation axis Ax1 (right side in FIG. 13) is relative to the rotation axis Ax1. The image is shifted (skewed) towards the top of the figure. On the other hand, the center C2 of the second planetary gear 302 located on the output side of the rotation axis Ax1 (left side in FIG. 13) is shifted (biased) downward in the figure with respect to the rotation axis Ax1. Here, the distance ΔL1 between the rotation axis Ax1 and the center C1 is the eccentricity of the first planetary gear 301 with respect to the rotation axis Ax1, and the distance ΔL2 between the rotation axis Ax1 and the center C2 is the eccentricity of the first planetary gear 301 with respect to the rotation axis Ax1. 2 is the eccentricity of the planetary gear 302. In this way, by disposing the plurality of planetary gears 3 evenly in the circumferential direction around the rotation axis Ax1, it is possible to balance the weight among the plurality of planetary gears 3.

The centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are located 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In this embodiment, the eccentricity amount ΔL1 and the eccentricity amount ΔL2 have opposite directions when viewed from the rotation axis Ax1, but their absolute values are the same.

More specifically, each of the eccentric shafts 7A, 7B, and 7C has two eccentric parts 72 for one shaft center part 71, respectively. The eccentricity of the center of these two eccentric parts 72 from the center of the shaft center part 71 is the same as the eccentricity ΔL1, ΔL2 of the first planetary gear 301 and the second planetary gear 302 with respect to the rotation axis Ax1, respectively. The shapes of the plurality of eccentric shafts 7A, 7B, and 7C are common. The plurality of crankshaft gears 502A, 502B, and 502C also have the same shape.

Further, the carrier flange 18 and the output flange 19 are arranged on both sides of the first planetary gear 301 and the second planetary gear 302 in a direction parallel to the rotation axis Ax1. Both ends of each eccentric shaft 7A, 7B, 7C are held by the carrier flange 18 and the output flange 19 via rolling bearings 41, 42. That is, each eccentric shaft 7A, 7B, 7C is held by the carrier flange 18 and the output flange 19 in a rotatable state on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1.

An eccentric bearing 5 is mounted on the eccentric portion 72 of each eccentric shaft 7A, 7B, 7C. Three openings 33 corresponding to the three eccentric shafts 7A, 7B, and 7C are formed in each of the first planetary gear 301 and the second planetary gear 302. The eccentric bearing 5 is accommodated in each opening 33. In other words, the eccentric bearings 5 are attached to the first planetary gear 301 and the second planetary gear 302, and the eccentric shafts 7A, 7B, 7C are inserted into the eccentric bearings 5, so that the eccentric bearings 5 And each eccentric shaft 7A, 7B, 7C is combined with the planetary gear 3. In the gear device 1A according to the present embodiment, the inner pin 4 is omitted, and instead of the inner pin 4, a plurality of eccentric shafts 7A, 7B, and 7C are used to remove the oscillation component (revolution component) of the planetary gear 3. , it is possible to extract the rotation (rotation component) of the planetary gear 3.

According to the configuration described above, a rotational force as an input is applied to the input shaft 500, and the input shaft 500 rotates around the rotation axis Ax1, so that this rotational force is transferred from the input gear 501 to the plurality of eccentric shafts 7A. , 7B, and 7C. That is, when the input gear 501 rotates, the three crankshaft gears 502A, 502B, and 502C that are meshed with the input gear 501 at the same time rotate in the same direction and at the same rotational speed. Since the eccentric shafts 7A, 7B, 7C are spline connected to each crankshaft gear 502A, 502B, 502C, the three eccentric shafts 7A, 7B, 7C connect the input gear 501 and the crankshaft gear 502A, 502B, 502C. Rotates in the same direction at the same speed while being decelerated by the tooth ratio. As a result, the three eccentric portions 72 formed at the same position on the input side of the rotation axis Ax1 in the three eccentric shafts 7A, 7B, and 7C rotate synchronously, causing the first planetary gear 301 to swing. Further, the three eccentric portions 72 formed at the same position on the output side of the rotating shaft Ax1 in the three eccentric shafts 7A, 7B, and 7C rotate synchronously, causing the second planetary gear 302 to swing.

As a result, the axial center portions 71 of the plurality of eccentric shafts 7A, 7B, and 7C each rotate (rotate) around the rotation axis Ax1, so that the first planetary gear 301 and the second planetary gear 302 rotate around the rotation axis Ax1. It rotates (eccentric movement) around the rotation axis Ax1 with a phase difference of 180 degrees.

Here, the first planetary gear 301 and the second planetary gear 302 are each internally meshed with the internal gear 2. Therefore, each time the first planetary gear 301 and the second planetary gear 302 swing once, the first planetary gear 301 and the second planetary gear 302 move with respect to the internal gear 2 (the internal teeth 21 and the external teeth 31 A phase shift occurs in the circumferential direction due to the difference in the number of teeth (with), resulting in rotation. This rotation is transmitted to the carrier flange 18 and the output flange 19 as each eccentric shaft 7A, 7B, 7C revolves around the axis (rotation axis Ax1) of the internal gear 2. Thereby, the carrier flange 18 and the output flange 19 can be rotated relative to the gear body (the case 10 integrated therewith) around the rotation axis Ax1.

In short, the gear device 1A according to the present embodiment differs from the basic configuration in that the planetary gear 3 is oscillated by a plurality of eccentric shafts 7A, 7B, and 7C arranged at positions offset from the rotation axis Ax1. , is the same as the basic configuration in that rotational output is obtained using the swing of the planetary gear 3. That is, in the gear device 1A, when the planetary gear 3 swings and the meshing position between the internal teeth 21 and the external teeth 31 moves in the circumferential direction of the internal gear 2, the planetary gear 3 and the internal gear 2 Relative rotation according to the difference in the number of teeth occurs between both gears (internal gear 2 and planetary gear 3). Here, if the internal gear 2 is fixed, the planetary gear 3 will rotate (rotate) as the two gears rotate relative to each other. As a result, a rotational output is obtained from the planetary gear 3, which is reduced at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

More specifically, in the gear device 1A according to this embodiment, the bearing member 6A includes a first bearing member 601A and a second bearing member 602A. The first bearing member 601A and the second bearing member 602A each consist of an angular ball bearing. Specifically, as shown in FIG. 13, the first bearing member 601A is arranged on the input side (right side in FIG. 13) of the rotation axis Ax1 when viewed from the planetary gear 3, and A second bearing member 602A is arranged on the output side (left side in FIG. 13). The bearing member 6A is capable of handling loads in the radial direction, loads in the thrust direction (direction along the rotation axis Ax1), and bending force (bending moment load) with respect to the rotation axis Ax1 at the first bearing member 601A and the second bearing member 602A. It is constructed to withstand both.

Here, the first bearing member 601A and the second bearing member 602A are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and in opposite directions to each other in the direction parallel to the rotation axis Ax1. In other words, the bearing member 6A is a "combined angular ball bearing" that is a combination of a plurality of (here, two) angular ball bearings. Here, as an example, the first bearing member 601A and the second bearing member 602A are of a "back-to-back combination type" that receives a load in the thrust direction (direction along the rotation axis Ax1) in which the respective inner rings approach each other. Furthermore, in the gear device 1A, the first bearing member 601A and the second bearing member 602A are assembled in a state where an appropriate preload is applied to the inner rings by tightening the respective inner rings closer to each other.

Further, the gear device 1A according to the present embodiment includes a carrier flange 18 and an output flange 19. The carrier flange 18 and the output flange 19 are arranged on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1, and are coupled to each other through the carrier hole 34 of the planetary gear 3 (see FIG. 13). Specifically, as shown in FIG. 13, the carrier flange 18 is disposed on the input side of the rotation axis Ax1 when viewed from the planetary gear 3 (on the right side in FIG. An output flange 19 is arranged on the side (left side in FIG. 13). The inner ring of the bearing member 6A (each of the first bearing member 601A and the second bearing member 602A) is fixed to the carrier flange 18 and the output flange 19. In this embodiment, as an example, the inner ring of the first bearing member 601A is seamlessly integrated with the carrier flange 18. Similarly, the inner ring of the second bearing member 602A is seamlessly integrated with the output flange 19.

The output flange 19 has a plurality of (for example, three) carrier pins 191 (see FIG. 12) that protrude from one surface of the output flange 19 toward the input side of the rotation axis Ax1. These plurality of carrier pins 191 each pass through a plurality of (for example, three) carrier holes 34 formed in the planetary gear 3, and their tips are fixed to the carrier flange 18 with carrier bolts. Here, a gap is ensured between the carrier pin 191 and the inner circumferential surface of the carrier hole 34, and the carrier pin 191 can move within the carrier hole 34, that is, move relative to the center of the carrier hole 34. It is possible. This prevents the carrier pin 191 from coming into contact with the inner circumferential surface of the carrier hole 34 when the planetary gear 3 swings.

Thereby, the gear device 1A is used so that the rotation equivalent to the autorotation component of the planetary gear 3 is extracted as the rotation of the carrier flange 18 and the output flange 19, which are integrated with the inner ring 61 of the bearing member 6A. That is, in the basic configuration, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted as an autorotation component of the planetary gear 3 from the inner ring 61 connected to the planetary gear 3 by a plurality of inner pins 4. It will be done. In contrast, in this embodiment, the relative rotation between the planetary gear 3 and the internal gear 2 is extracted from the carrier flange 18 and the output flange 19 that are integrated with the inner ring. In this embodiment, as an example, the gear device 1A is used with the outer ring 62 (see FIG. 13) of the bearing member 6A fixed to the case 10, which is a fixed member. That is, the planetary gear 3 is connected to the carrier flange 18 and the output flange 19, which are rotating members, by a plurality of eccentric shafts 7A, 7B, and 7C, and the gear body 22 is fixed to a fixed member, so that the planetary gear 3 and the internal teeth are connected to each other. Relative rotation with the gear 2 is taken out from the rotating members (carrier flange 18 and output flange 19). In other words, in this embodiment, when the planetary gear 3 rotates relative to the gear body 22, the rotational force of the carrier flange 18 and the output flange 19 is extracted as output.

Furthermore, in this embodiment, the case 10 is seamlessly integrated with the gear body 22 of the internal gear 2. That is, in the basic configuration, the gear main body 22 of the internal gear 2 is used while being fixed to the case 10 together with the outer ring 62 of the bearing member 6. On the other hand, in this embodiment, the gear body 22, which is a fixed member, and the case 10 are provided seamlessly and continuously in the direction parallel to the rotation axis Ax1.

More specifically, the case 10 has a cylindrical shape and constitutes the outer shell of the gear device 1A. In this embodiment, the central axis of the cylindrical case 10 is configured to coincide with the rotation axis Ax1. That is, at least the outer circumferential surface of the case 10 is a perfect circle centered on the rotation axis Ax1 in plan view (viewed from one direction of the rotation axis Ax1). The case 10 is formed into a cylindrical shape with both end faces open in the direction of the rotation axis Ax1. Here, the gear body 22 of the internal gear 2 is seamlessly integrated into the case 10, and the case 10 and the gear body 22 are treated as one component. Therefore, the inner peripheral surface of the case 10 includes the inner peripheral surface 221 of the gear body 22. Furthermore, an outer ring 62 of the bearing member 6A is fixed to the case 10. That is, the outer ring 62 of the first bearing member 601A is fitted and fixed on the input side (right side in FIG. 13) of the rotating shaft Ax1 when viewed from the gear body 22 on the inner circumferential surface of the case 10. On the other hand, the outer ring 62 of the second bearing member 602A is fitted and fixed on the output side (left side in FIG. 13) of the rotating shaft Ax1 when viewed from the gear body 22 on the inner peripheral surface of the case 10.

Furthermore, the end face of the case 10 on the input side (the right side in FIG. 13) of the rotation axis Ax1 is closed by the carrier flange 18, and the end face of the output side (the left side in FIG. 13) of the rotation axis Ax1 in the case 10 is closed by the output flange 19. occluded by Therefore, as shown in FIG. 13, in the space surrounded by the case 10, the carrier flange 18, and the output flange 19, the planetary gears 3 (the first planetary gear 301 and the second planetary gear 302), the plurality of outer pins 23, Components such as the eccentric bearing 5 and the like are housed therein.

The gear device 1A according to the present embodiment also includes a holding member 80 that is disposed inside the gear body 22 and holds the plurality of outer pins 23 between it and the gear body 22 in the radial direction (radial direction of the gear body 22). It further includes: The holding member 80 is arranged between the two planetary gears 3, the first planetary gear 301 and the second planetary gear 302. The holding member 80 has a plurality of outer circumferential grooves 801 on the outer circumferential surface for holding the plurality of outer pins 23. That is, in the present embodiment, the holding member 80 provided in place of the support body 8 in the basic structure holds the plurality of outer pins 23 between it and the gear body 22, so that the holding member 80 can be removed from the inner circumferential surface 221 of the gear body 22. It functions as a "stopper" that suppresses the movement of the outer pin 23 in the direction of separation. In short, each of the plurality of outer pins 23 is prevented from moving away from the gear body 22 by contacting the outer circumferential surface of the holding member 80, and by being fitted into the outer circumferential groove 801, each of the plurality of outer pins 23 is centered around the rotation axis Ax1. Movement in the circumferential direction is also restricted. In other words, the outer pin 23 is positioned by the holding member 80 and the gear body 22 not only in the radial direction but also in the circumferential direction.

Therefore, play is less likely to occur between the outer pin 23, the holding member 80, and the gear body 22, and when the inner teeth 21 (outer pins 23) and the outer teeth 31 engage, the outer teeth 31 close the inner circumferential groove 222. Even if a force in the direction of pulling the outer pin 23 acts on the outer pin 23, the meshing between the inner teeth 21 and the outer teeth 31 is unlikely to become unstable. Therefore, the gear device 1A according to the present embodiment has the advantage that the meshing between the internal teeth 21 and the external teeth 31 is likely to be stable.

<Relationship between input gear and crankshaft gear>
Next, in the gear device 1A according to this embodiment, the relationship between the input gear 501 and the plurality of crankshaft gears 502A, 502B, and 502C will be described in detail.

A plurality of (three in this embodiment) crankshaft gears 502A, 502B, and 502C are arranged around the input gear 501 so as to mesh with the input gear 501. When the input gear 501 as a sun gear located at the center rotates, the plurality of crankshaft gears 502A, 502B, and 502C as pinion gears arranged around it rotate in the same direction and at the same rotational speed. , the rotational force of the input shaft 500 is distributed to the plurality of eccentric shafts 7A, 7B, and 7C. Therefore, the plurality of eccentric shafts 7A, 7B, 7C rotate in the same direction at the same rotational speed while being decelerated by the tooth number ratio of the input gear 501 and each crankshaft gear 502A, 502B, 502C. In short, the input gear 501 as a sun gear and the plurality of crankshaft gears 502A, 502B, and 502C as pinion gears constitute a primary reduction mechanism of the gear device 1A.

By the way, between gears such as the input gear 501 and the plurality of crankshaft gears 502A, 502B, and 502C, vibrations in the circumferential direction of the input gear 501 and vibrations in the radial direction of the input gear 501 occur due to meshing transmission errors. There is. In the gear device 1A according to the present embodiment, the following configuration is adopted in order to reduce vibrations occurring at the meshing portion between the gears.

A gear device 1A according to this embodiment includes an internal gear 2 and a planetary gear 3. The internal gear 2 includes an annular gear main body 22 and a plurality of outer pins 23 that are rotatably held in a plurality of inner circumferential grooves 223 formed in an inner circumferential surface 221 of the gear main body 22 and constitute internal teeth 21. and has. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The gear device 1A rotates the planetary gear 3 relative to the internal gear 2 by swinging the planetary gear 3 around the rotation axis Ax1. Here, when the planetary gear 3 swings, mutually different meshing phases occur between the meshing portions of the first gear with the plurality of second gears centered on the rotation axis Ax1.

"Meshing transmission error" in the present disclosure means the degree of nonlinearity between the rotation angle of the driving gear (first gear) and the rotation angle of the driven gear (second gear). In addition, "meshing phase" as used in the present disclosure means a timing shift in meshing with the sun gear (first gear) at the position of each pinion gear (second gear). For example, when the tooth tips of the crankshaft gear 502A are meshing with the tooth roots of the input gear 501, if the tooth tips of another crankshaft gear 502B are also meshing with the tooth roots of the input gear 501, then these crankshaft gears 502A , 502B, there is no shift in the timing of meshing, and the meshing phase (phase difference) is "absent" (zero). In this embodiment, the "first gear" is the input gear 501 as a sun gear, and the "second gears" are the plurality of crankshaft gears 502A, 502B, and 502C as pinion gears.

That is, the gear device 1A according to the present embodiment has different meshes when the planetary gear 3 swings between the meshing portions of the input gear 501 with the plurality of crankshaft gears 502A, 502B, and 502C centered on the rotation axis Ax1. The structure is such that a phase occurs. This makes it possible to reduce circumferential vibrations and radial vibrations due to meshing transmission errors between the first gear (input gear 501) and the plurality of second gears (crankshaft gears 502A, 502B, 502C). be.

More specifically, as shown in FIG. 14, the gear device 1A according to this embodiment includes an input gear 501 that rotates around a rotation axis Ax1, and a plurality of crankshaft gears 502A, 502B, and 502C. The plurality of crankshaft gears 502A, 502B, and 502C are arranged around the input gear 501 so as to mesh with the input gear 501, and rotate in synchronization with each other when the input gear 501 rotates, thereby causing the planetary gear 3 to swing. . The first gear includes an input gear 501, and the second gear includes a plurality of crankshaft gears 502A, 502B, and 502C. In FIG. 14, only the input gear 501 and the plurality of crankshaft gears 502A, 502B, and 502C are illustrated, and illustration of the other gears is omitted.

This makes it possible to reduce circumferential vibrations and radial vibrations due to meshing transmission errors between the input gear 501 and the plurality of crankshaft gears 502A, 502B, and 502C that constitute the primary reduction mechanism of the gear device 1A. be.

Here, the plurality of second gears (crankshaft gears 502A, 502B, 502C) are arranged at unequal intervals on a virtual circle Cv1 centered on the rotation axis Ax1. Specifically, as shown in FIG. 14, the arrangement angles δi of the plurality of crankshaft gears 502A, 502B, and 502C have different values. Here, the arrangement angle δi is the interval (angle) between the centers of adjacent second gears (crankshaft gears 502A, 502B, 502C) on the virtual circle Cv1 centered on the rotation axis Ax1.

In this embodiment, in particular, the arrangement angle δ1 is the distance between the centers of the crankshaft gears 502A and 502B, the arrangement angle δ2 is the distance between the centers of the crankshaft gears 502B and 502C, and the arrangement angle δ3 is the center of the crankshaft gears 502C and 502A. This is the distance between the two. Furthermore, the arrangement angle δi is the value (2π/k) obtained by dividing “2π” by the number k (“k=3” in this embodiment) of the second gears (crankshaft gears 502A, 502B, 502C). It does not match. Furthermore, none of the arrangement angles δi matches the value obtained by dividing "2π" by the number of teeth Zs of the first gear (input gear 501), that is, an integral number n times the pitch (2π/Zs) of the first gear. Therefore, the arrangement angle δi (i=1, 2, 3) satisfies the relationship of Equation 1 below.
δ1≠δ2≠δ3≠2π/k≠2π/Zs×n (Formula 1)

As a first comparative example of the present embodiment, the meshing phase is "absent" (zero) between the meshing parts of the first gear (input gear 501) and the plurality of second gears (crankshaft gears 502A, 502B, 502C). Assume the following configuration. In the first comparative example, the number of teeth Zs of the first gear (input gear 501) is divided by the number k of the second gears (crankshaft gears 502A, 502B, 502C) (in this embodiment, "k=3"). The value (Zs/k) is an integer. Furthermore, in the first comparative example, the plurality of second gears (crankshaft gears 502A, 502B, 502C) are arranged at equal intervals on a virtual circle Cv1 centered on the rotation axis Ax1, and the arrangement angle δi (i= 1, 2, 3) satisfy the relationship of Equation 2 below.
δ1=δ2=δ3=2π/k (Formula 2)

Furthermore, as a second comparative example of the present embodiment, the meshing phase is equally divided between the meshing parts of the first gear (input gear 501) and the plurality of second gears (crankshaft gears 502A, 502B, 502C). Assume a configuration with That is, in the second comparative example, the meshing phase occurs evenly between the meshing portions of the input gear 501 with the plurality of crankshaft gears 502A, 502B, and 502C. Therefore, the meshing phase between the crankshaft gears 502A and 502B, the meshing phase between the crankshaft gears 502B and 502C, and the meshing phase between the crankshaft gears 502C and 502A are all based on the pitch (2π/Zs) of the first gear. It is the value (2π/(Zs×k)) divided by the number k of the second gears (crankshaft gears 502A, 502B, 502C) (“k=3” in this embodiment).

Here, in the second comparative example, the number of teeth Zs of the first gear (input gear 501) is the number k of the second gears (crankshaft gears 502A, 502B, 502C) ("k=3" in this embodiment). The value divided by (Zs/k) is not an integer. Furthermore, in the second comparative example, the plurality of second gears (crankshaft gears 502A, 502B, 502C) are arranged at equal intervals on a virtual circle Cv1 centered on the rotation axis Ax1, and the arrangement angle δi (i= 1, 2, 3) satisfy the relationship of Equation 2 above.

FIG. 15 shows an input gear 501 and a plurality of crankshaft gears 502A for each of the present embodiment, a first comparative example (no meshing phase, equally spaced arrangement), and a second comparative example (equal meshing phase, equally spaced arrangement). . In FIG. 15, force F1 (see FIG. 14) that acts on the input gear 501 at the meshing portion with the crankshaft gear 502A, force F2 (see FIG. 14) that acts on the meshing portion of the input gear 501 with the crankshaft gear 502B, and the crankshaft gear The force F3 (see FIG. 14) acting on the meshing portion with 502C is shown for one pitch (one period φ0) of the first gear. The force F0 is a composite component of the forces F1, F2, and F3 in the circumferential direction of the input gear 501 (F0=F1+F2+F3). Here, in FIG. 15, in order to explain the action of the meshing phase, the vibrations in the circumferential direction (rotational direction) generated at each meshing part are treated as sinusoidal periodic components, and the magnitudes (amplitudes) of these are all equal. A typical example is shown below.

As is clear from FIG. 15, in the first comparative example in which the meshing phase is "none" (zero), there is no phase difference between forces F1, F2, and F3, so the fluctuation (amplitude ) is k (=3) times the fluctuation component of each force F1, F2, F3. On the other hand, in the second comparative example in which the meshing phase is equally divided, there is a phase difference between the forces F1, F2, and F3 that is obtained by equally dividing one period φ0 by k (=3) (that is, φ1=φ0×1/ 3, φ2=φ0×2/3), the fluctuation (amplitude) of the combined force F0 is 0 (zero). On the other hand, in this embodiment, a phase difference occurs between the forces F1, F2, and F3 with one period φ0 distributed unequally, so the fluctuation (amplitude) of the combined force F0 is determined by the first comparison. The value is between the example and the second comparative example. In FIG. 15, as an example, it is assumed that "φ1=0.49×φ0" and "φ2=0.63×φ0".

Similarly, regarding the radial vibration of the input gear 501, the meshing phase is "none" (zero), and a plurality of second gears (crankshaft gears 502A, 502B, 502C) are arranged at equal intervals. In the comparative example, the amplitude is 0 (zero) because the fluctuation components are completely balanced. On the other hand, in a second comparative example in which the meshing phase is equally divided and a plurality of second gears (crankshaft gears 502A, 502B, 502C) are arranged at equal intervals, the amplitude of the radial vibration of the input gear 501 is This is k (=3) times the fluctuation component occurring between each second gear. On the other hand, in this embodiment, the radial vibration of the input gear 501 also has a value between the first comparative example and the second comparative example.

As explained above, according to the gear device 1A according to the present embodiment, vibration in the circumferential direction can be suppressed to be smaller than the first comparative example without meshing phase, and vibration in the radial direction can be suppressed evenly in the meshing phase. It can be suppressed to be smaller than the second comparative example. Therefore, in the gear device 1A according to the present embodiment, it is possible to reduce both the circumferential vibration and the radial vibration by suppressing them as small as possible.

By the way, in a configuration including a plurality of second gears (crankshaft gears 502A, 502B, 502C) and eccentric shafts 7A, 7B, 7C like the gear device 1A according to the present embodiment, these second gears and It is preferable to use common parts (same shape) for the eccentric shafts 7A, 7B, and 7C. When a plurality of second gears are arranged at equal intervals as in the first comparative example and the second comparative example, the number of teeth Zs of the first gear (input gear 501), the number of teeth Zp of the second gear, and the number of teeth Zp of the second gear If the number k of gears satisfies the relationship of formula 3 below, common parts can be used for the plurality of second gears and eccentric shafts 7A, 7B, and 7C.
(Zs+Zp)/k=integer (Formula 3)

On the other hand, when the plurality of second gears (crankshaft gears 502A, 502B, 502C) are arranged at unequal intervals on the virtual circle Cv1 as in the present embodiment, even if the relationship of the above formula 3 is satisfied, It is not necessarily possible to use common parts for the plurality of second gears and eccentric shafts 7A, 7B, and 7C. That is, it may be necessary to use parts with different specifications for at least one of the plurality of crankshaft gears 502A, 502B, 502C and the plurality of eccentric shafts 7A, 7B, 7C. For eccentric shafts 7A, 7B, and 7C, the shaft spline phase and cam phase must be different from each other, and for crankshaft gears 502A, 502B, and 502C, the hole spline phase and gear phase must be different from each other. . In this way, using parts with different specifications for the plurality of crankshaft gears 502A, 502B, 502C or the plurality of eccentric shafts 7A, 7B, 7C may lead to an increase in the cost of the parts and the assembly cost, for example.

Therefore, in this embodiment, by adopting the configuration described below, it is possible to use common parts for the plurality of second gears and eccentric shafts 7A, 7B, and 7C. That is, in the gear device 1A according to the present embodiment, when focusing on a pair of crankshaft gears 502A, 502B, 502C that are adjacent in the circumferential direction of the input gear 501 among the plurality of crankshaft gears 502A, 502B, 502C, The arrangement angle δi of the crankshaft gears 502A, 502B, 502C around the rotation axis Ax1, the number of teeth Zs of the input gear 501, and the number of teeth Zp of each of the pair of crankshaft gears 502A, 502B, 502C are as follows. Using the integer n, the following equation 4 is satisfied.
δi=(2π/(Zs+Zp))×n (Formula 4)

More specifically, as shown in FIG. 16, the phases of the eccentric portions 72 need to be the same in the plurality of eccentric shafts 7A, 7B, and 7C. Here, when focusing on the pair of adjacent crankshaft gears 502A and 502B, when the crankshaft gear 502A revolves around the rotation axis Ax1 by an amount of the arrangement angle δ1 and moves to the position of the crankshaft gear 502B, The rotation angle θ1 of the crankshaft gear 502A is expressed by the following equation 5.
θ1=δ1×Zs/Zp (Formula 5)

The above formula 5 is calculated as the rotation angle θ2 of the crankshaft gear 502B when the crankshaft gear 502B is revolved by an arrangement angle δ2, and the rotation angle θ2 of the crankshaft gear 502B when the crankshaft gear 502C is revolved by an arrangement angle δ3. When expanded to the rotation angle θ3 of 502C, the rotation angle θi (i=1, 2, 3) is expressed by the following equation 6.
θi=δi×Zs/Zp (Formula 6)

Further, when each crankshaft gear 502A, 502B, 502C revolves by the arrangement angle δi and moves to the position of the adjacent crankshaft gear 502A, 502B, 502C, in order for the phase of the eccentric portion 72 to remain unchanged, each The eccentric shafts 7A, 7B, and 7C need to rotate (rotate) n times (n is an integer). Therefore, when the sum of the arrangement angle δi and the rotation angle θi (θi+δi) is normalized by the pitch (2π/Zp) of the crankshaft gears 502A, 502B, and 502C, multiple It becomes possible to use common parts for the second gear and the eccentric shafts 7A, 7B, and 7C.
(θi+δi)/(2π/Zp)=n (Formula 7)

From equations 6 and 7 above, when the arrangement angle δi satisfies equation 4 above, it is possible to use common parts for the plurality of second gears (crankshaft gears 502A, 502B, 502C) and eccentric shafts 7A, 7B, 7C. It becomes possible. As a result, compared to the case where parts with different specifications are used for the plurality of crankshaft gears 502A, 502B, 502C or the plurality of eccentric shafts 7A, 7B, 7C, it is possible to keep the cost of parts and assembly costs low, for example. Become.

<Modified example>
Embodiment 1 is just one of various embodiments of the present disclosure. Embodiment 1 can be modified in various ways depending on the design, etc., as long as the objective of the present disclosure can be achieved. Furthermore, all the drawings referred to in this disclosure are schematic drawings, and the ratios of the sizes and thicknesses of each component in the drawings do not necessarily reflect the actual dimensional ratios. . Modifications of the first embodiment will be listed below. The modified examples described below can be applied in combination as appropriate.

Further, the bearing member 6A may be a cross roller bearing as in the basic configuration, or may be a deep groove ball bearing, a four-point contact ball bearing, or the like.

In the first embodiment, the gear device 1A has two types of planetary gears 3, but the gear device 1A may include three or more planetary gears 3. For example, when the gear device 1A includes three planetary gears 3, it is preferable that these three planetary gears 3 are arranged with a phase difference of 120 degrees around the rotation axis Ax1. Further, the gear device 1A may include only one planetary gear 3. Alternatively, when the gear device 1A includes three planetary gears 3, two of these three planetary gears 3 are in the same phase, and the remaining one planetary gear 3 has a rotation angle of 180 degrees around the rotation axis Ax1. They may be arranged with a phase difference.

In addition, the number of teeth Zs of the first gear (input gear 501), the number of teeth Zp of the second gear (crankshaft gear 502A, 502B, 502C), the number of teeth Zp of the second gear (crankshaft gear 502A, 502B, 502C), the number of external pins 23 (the number of internal teeth 21), the number of external teeth 31, etc. are merely examples, and can be changed as appropriate.

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

Further, 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. The material of the holding member 80 is not limited to resin such as engineering plastic, and may be, for example, metal.

Further, the gear device 1A only needs to be able to output the relative rotation between the inner ring and the outer ring 62 of the bearing member 6A, and the rotational force of the inner ring (carrier flange 18 and output flange 19) can be taken out as the output. It is not limited to the configuration. For example, the rotational force of the outer ring 62 (case 10) that rotates relative to the inner ring may be extracted as an output.

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

(Embodiment 2)
As shown in FIG. 17, the internal meshing planetary gear device 1B (hereinafter also simply referred to as "gear device 1B") according to the present embodiment includes a plurality of planetary gears 3 (a first planetary gear 301 and a second planetary gear 302). ) is different from the gear device 1 according to the basic configuration. Hereinafter, configurations similar to the basic configuration will be given the same reference numerals and descriptions will be omitted as appropriate. FIG. 17 is a schematic cross-sectional view of the gear device 1B.

In the gear device 1B according to the present embodiment, similarly to the first embodiment, the planetary gear 3 includes a first planetary gear 301 and a second planetary gear 302, and rotation of the first planetary gear 301 and the second planetary gear 302. A carrier flange 18 and an output flange 19 are arranged on both sides in a direction parallel to the axis Ax1.

18 and 19 show the states of the first planetary gear 301 and the second planetary gear 302 at a certain point in time. FIG. 18 is a sectional view taken along the line A1-A1 in FIG. 17, and shows the first planetary gear 301. FIG. 19 is a sectional view taken along the line B1-B1 in FIG. 17, showing the second planetary gear 302. However, in FIGS. 18 and 19, illustration of the retainer 54 is omitted, and hatching is omitted even in the cross section. As shown in FIGS. 18 and 19, the centers C1 and C2 of the first planetary gear 301 and the second planetary gear 302 are located approximately 180 degrees rotationally symmetrical with respect to the rotation axis Ax1. In the present embodiment, the eccentricity ΔL1 and the eccentricity ΔL2 have opposite directions when viewed from the rotation axis Ax1, but their absolute values are substantially the same. According to the above-described configuration, as the shaft center portion 71 rotates (rotates) around the rotation axis Ax1, the first planetary gear 301 and the second planetary gear 302 have a phase difference of approximately 180 degrees around the rotation axis Ax1. It rotates (eccentric movement) around the rotation axis Ax1.

By arranging the plurality of planetary gears 3 substantially evenly in the circumferential direction around the rotation axis Ax1, it is possible to maintain a weight balance among the plurality of planetary gears 3. In the gear device 1B according to the present embodiment, the weight balance is maintained between the plurality of planetary gears 3 in this way, so the gap 75 (see FIG. 3) of the eccentric shaft 7 is omitted.

Furthermore, in the gear device 1B, similarly to the first embodiment, the bearing member 6A includes a first bearing member 601A and a second bearing member 602A. Moreover, the eccentric shaft 7 has two eccentric parts 72 with respect to one shaft center part 71, similarly to the first embodiment. Both ends of the eccentric shaft 7 are held by the carrier flange 18 and the output flange 19 via a first bearing 91 and a second bearing 92. That is, the eccentric shaft 7 is held by the carrier flange 18 and the output flange 19 in a rotatable state on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. Furthermore, in the gear device 1B, the case 10 is seamlessly integrated with the gear body 22 of the internal gear 2, as in the first embodiment.

Further, the gear device 1B according to the present embodiment has the following points: the structure (support structure 40) that supports the plurality of inner pins 4 is a structure in which both ends of the inner pins 4 are held by rolling bearings 41, 42. It differs from the basic configuration. That is, the gear device 1B includes a plurality of sets of rolling bearings 41 and 42 that hold each of the plurality of inner pins 4 on both sides of the planetary gear 3 in a direction parallel to the rotation axis Ax1. Each of the plurality of inner pins 4 is held by each set of rolling bearings 41 and 42 in a state where it can rotate. Here, the plurality of inner pins 4 are inserted into the plurality of loose fitting holes 32 formed in the planetary gear 3, and while revolving within the loose fitting holes 32, the plurality of inner pins 4 are connected to the internal gear 2 with respect to the rotation axis Ax1. Rotate relative to the center.

However, the rolling bearings 41 and 42 are fixed to the inner ring 61 of the bearing member 6A, and the inner pin 4 is held by the inner ring 61 of the bearing member 6A via the rolling bearings 41 and 42. Therefore, the gear device 1B according to this embodiment is also similar to the basic configuration in that each of the plurality of inner pins 4 is held by the inner ring 61 in a rotatable state.

Furthermore, in the gear device 1B according to the present embodiment, the bush 70 is provided with a fixing structure 701 for fixing a mating member to the eccentric shaft 7 as an input shaft. That is, the gear device 1B includes an input shaft (eccentric shaft 7) that eccentrically swings the planetary gear 3, and a bush 70. The bush 70 has a fixing structure 701 for fixing a mating member, is coupled to the input shaft (eccentric shaft 7), and rotates together with the input shaft (eccentric shaft 7).

Furthermore, in this embodiment, as shown in FIG. 17, the eccentric bearing 5 is made of a roller bearing instead of the deep groove ball bearing described in the basic configuration. That is, in the gear device 1B according to the present embodiment, the eccentric bearing 5 uses columnar (cylindrical) rollers as the rolling elements 53. Furthermore, in this embodiment, the eccentric inner ring 51 (see FIG. 3) and the eccentric outer ring 52 (see FIG. 3) are omitted. Therefore, the inner peripheral surface of the planetary gear 3 (the opening 33 thereof) becomes the rolling surface of the plurality of rolling elements 53 instead of the eccentric outer ring 52, and the outer peripheral surface of the eccentric part 72 becomes the rolling surface of the plurality of rolling elements 53 instead of the eccentric inner ring 51. This becomes the rolling surface of the rolling element 53. In this embodiment, the eccentric bearing 5 has a retainer 54, and the plurality of rolling elements 53 are each held by the retainer 54 in a rotatable state. The cage 54 holds the plurality of rolling elements 53 at equal pitches in the circumferential direction of the eccentric portion 72. Further, the retainer 54 is not fixed to the planetary gears 3 and the eccentric shaft 7, and is rotatable relative to each of the planetary gears 3 and the eccentric shaft 7. As a result, as the retainer 54 rotates, the plurality of rolling elements 53 held by the retainer 54 move in the circumferential direction of the eccentric portion 72 .

Furthermore, the gear device 1B according to this embodiment includes a spacer 55, as shown in FIG. The spacer 55 is arranged between the first bearing 91 and the second bearing 92 and the eccentric bearing 5. Specifically, the spacer 55 is provided between the first bearing 91 and the eccentric bearing 5 on the first planetary gear 301 side, and between the second bearing 92 and the eccentric bearing 5 on the second planetary gear 302 side. , respectively. The spacer 55 has an annular shape in which at least the inner circumferential surface is a perfect circle in plan view. The spacer 55 functions as a "holder" for the eccentric bearing 5, and restricts movement of the eccentric bearing 5 (particularly the retainer 54) in a direction parallel to the rotation axis Ax1.

Here, the spacer 55 secures a gap between the first bearing 91 and the second bearing 92 and the outer ring thereof. Therefore, in the first bearing 91 and the second bearing 92, the outer rings thereof do not contact the spacer 55, and only the inner rings thereof contact the spacer 55. On the other hand, a gap is secured between the first bearing member 601A and the second bearing member 602A, which are the bearing members 6A, with the planetary gear 3. Therefore, the first bearing member 601A and the second bearing member 602A do not come into contact with the planetary gear 3.

Further, the gear device 1B according to the present embodiment includes a holding member 80 instead of the support body 8, similarly to the first embodiment. The holding member 80 is a member that holds a plurality of outer pins 23 between it and the gear main body 22 in the radial direction (radial direction of the gear main body 22), and has a plurality of outer pins 23 held on its outer peripheral surface. It has an outer circumferential groove 801.

In addition to the above-mentioned points, for example, the number of teeth of the internal gear 2 and the planetary gear 3, the reduction ratio, the number of loose fitting holes 32 and the inner pins 4, and the specific shape and dimensions of each part, etc. There are appropriate differences between this embodiment and the basic configuration. For example, in the basic configuration, 18 loose fitting holes 32 and 18 inner pins 4 are provided, but in this embodiment, as an example, 6 each are provided.

Furthermore, in this embodiment, each of the plurality of inner pins 4 is configured to be removable in a state where at least the bearing member 6A, the internal gear 2, and the planetary gear 3 are combined. In other words, in the gear device 1B, the lateral parts of the plurality of inner pins 4 (at least one side in the direction parallel to the rotation axis Ax1) can be opened, and the inner pins 4 can be replaced from the lateral parts. be. However, the side portions of the plurality of inner pins 4 are not always open, but are covered by cover bodies 163 and 164 at least when the gear device 1B is used. The cover bodies 163 and 164 are removably attached to the carrier flange 18 and the output flange 19, for example.

By the way, the gear device 1B according to the present embodiment includes an internal gear 2 and a planetary gear 3 similarly to the first embodiment. The internal gear 2 includes an annular gear main body 22 and a plurality of outer pins 23 that are rotatably held in a plurality of inner circumferential grooves 223 formed in an inner circumferential surface 221 of the gear main body 22 and constitute internal teeth 21. and has. The planetary gear 3 has external teeth 31 that partially mesh with the internal teeth 21. The gear device 1B rotates the planetary gear 3 relative to the internal gear 2 by swinging the planetary gear 3 around the rotation axis Ax1. Here, when the planetary gear 3 swings, mutually different meshing phases occur between the meshing portions of the first gear with the plurality of second gears centered on the rotation axis Ax1.

More specifically, as shown in FIG. 20, the gear device 1B according to the present embodiment is provided with a first planetary gear 301 and a second planetary gear 302 as the planetary gears 3. The first gear includes an internal gear 2, and the plurality of second gears includes a first planetary gear 301 and a second planetary gear 302. This prevents circumferential vibrations and radial vibrations due to meshing transmission errors between the internal gear 2 and the plurality of planetary gears 3 (first planetary gear 301 and second planetary gear 302) of the gear device 1B. It is possible to reduce

Here, the plurality of second gears (the first planetary gear 301 and the second planetary gear 302) are arranged at unequal intervals on the virtual circle Cv1 centered on the rotation axis Ax1. Specifically, as shown in FIG. 20, the arrangement angles δi (i=1, 2) of the first planetary gear 301 and the second planetary gear 302 have different values. Further, the arrangement angle δi does not match the value obtained by dividing "2π" by the number of teeth Zs of the first gear (internal gear 2), that is, an integral number n times the pitch (2π/Zs) of the first gear. Therefore, the arrangement angle δi (i=1, 2) satisfies the relationship of equation 8 below.
δ1≠δ2≠2π/k≠2π/Zs×n (Formula 8)

As a first comparative example of the present embodiment, the meshing phase is "None" between the meshing parts of the first gear (internal gear 2) and the plurality of second gears (first planetary gear 301 and second planetary gear 302). ” (zero). In the first comparative example, the number of teeth Zs of the first gear (internal gear 2) is the number k of the second gears (first planetary gear 301 and second planetary gear 302) (in this embodiment, "k=2") ) is an integer. Further, in the first comparative example, the plurality of second gears are arranged at equal intervals on the virtual circle Cv1 centered on the rotation axis Ax1, and the arrangement angle δi (i = 1, 2) is calculated by the following formula 9. Satisfy the relationship.
δ1=δ2=2π/k (Formula 9)

Furthermore, as a second comparative example of the present embodiment, the meshing phase is different between the meshing portions of the first gear (internal gear 2) and the plurality of second gears (the first planetary gear 301 and the second planetary gear 302). Assume an equally divided configuration. That is, in the second comparative example, meshing phases occur evenly between the meshing portions of the internal gear 2 with the plurality of planetary gears 3 (the first planetary gear 301 and the second planetary gear 302). Therefore, the meshing phase between the first planetary gear 301 and the second planetary gear 302 is determined by changing the pitch (2π/Zs) of the first gear to the number k( In this embodiment, it is the value (2π/(Zs×k)) divided by “k=2”).

Here, in the second comparative example, the number of teeth Zs of the first gear (internal gear 2) is the number k of the second gears (first planetary gear 301 and second planetary gear 302) (in this embodiment, "k" = 2'') is not an integer. Furthermore, in the second comparative example, the plurality of second gears (the first planetary gear 301 and the second planetary gear 302) are arranged at equal intervals on the virtual circle Cv1 centered on the rotation axis Ax1, and the arrangement angle δi (i=1, 2) satisfies the relationship of Equation 9 above.

FIG. 21 shows an internal gear 2 and a plurality of planetary gears 3 for each of the present embodiment, a first comparative example (no meshing phase, equally spaced arrangement), and a second comparative example (equal meshing phase, equally spaced arrangement). (The first planetary gear 301 and the second planetary gear 302) are explanatory diagrams schematically representing vibrations in the circumferential direction of the internal gear 2 due to a meshing transmission error. In FIG. 21, the force F1 acting on the meshing part of the internal gear 2 with the first planetary gear 301 and the force F2 acting on the meshing part with the second planetary gear 302 are expressed as one pitch (one period) of the first gear. φ0) is shown. The force F0 is a composite component of the forces F1 and F2 in the circumferential direction of the internal gear 2 (F0=F1+F2). Here, in FIG. 21, in order to explain the action of the meshing phase, the vibrations in the circumferential direction (rotational direction) generated at each meshing part are treated as sinusoidal periodic components, and the magnitudes (amplitudes) of these are all equal. A typical example is shown below.

As is clear from FIG. 21, in the first comparative example where the meshing phase is "none" (zero), there is no phase difference between the forces F1 and F2, so the fluctuation (amplitude) of the combined force F0 is , k (=2) times the fluctuation component of each force F1, F2. On the other hand, in the second comparative example in which the meshing phase is equally divided, there is a phase difference between the forces F1 and F2, which is one period φ0 divided into k (=2) equal parts (that is, φ1 = φ0 × 1/2) Therefore, the fluctuation (amplitude) of the combined force F0 is 0 (zero). On the other hand, in this embodiment, a phase difference occurs between the forces F1 and F2 with one period φ0 distributed unequally (that is, φ1≠φ0×1/2), so the combined force F0 The fluctuation (amplitude) has a value between the first comparative example and the second comparative example.

Similarly, regarding the radial vibration of the internal gear 2, the meshing phase is "none" (zero), and the plurality of second gears (first planetary gear 301 and second planetary gear 302) are arranged at equal intervals. In the first comparative example, the amplitude is 0 (zero) because the fluctuation components are completely balanced. On the other hand, in a second comparative example in which the meshing phase is equally divided and a plurality of second gears (first planetary gear 301 and second planetary gear 302) are arranged at equal intervals, the vibration in the radial direction of the internal gear 2 The amplitude of is k (=2) times the fluctuation component occurring between each second gear. On the other hand, in this embodiment, the radial vibration of the internal gear 2 also has a value between the first comparative example and the second comparative example.

As explained above, according to the gear device 1B according to the present embodiment, vibrations in the circumferential direction can be suppressed smaller than in the first comparative example, and vibrations in the radial direction can be suppressed smaller than in the second comparative example. be able to. Therefore, in the gear device 1B according to the present embodiment, it is possible to reduce both the circumferential vibration and the radial vibration by suppressing them as small as possible.

<Application example>
As shown in FIG. 22, the gear device 1B according to this embodiment constitutes a robot joint device 200 together with a first member 201 and a second member 202. In other words, the robot joint device 200 according to the present embodiment includes the gear device 1B, the first member 201, and the second member 202. The first member 201 is fixed to the gear body 22. The second member 202 rotates relative to the first member 201 as the planetary gear 3 rotates relative to the internal gear 2 . FIG. 22 is a schematic cross-sectional view of the robot joint device 200.

In this embodiment, as an example, the first member 201 is fixed to the outer ring 62, and the second member 202 is fixed to the inner ring 61. As a result, the second member 202 rotates relative to the first member 201 as the planetary gear 3 rotates relative to the internal gear 2 . More specifically, the first member 201 is indirectly fixed to the outer ring 62 of the bearing member 6A by being fixed to the plurality of installation holes 111 formed in the case 10. By being fixed to the carrier flange 18, the second member 202 is indirectly fixed to the inner ring 61 of the bearing member 6A.

The robot joint device 200 configured in this manner functions as a joint device by the first member 201 and the second member 202 rotating relatively around the rotation axis Ax1. Here, by driving the eccentric shaft 7 of the gear device 1B with the first motor 203 as the drive source 101 (see FIG. 1), the first member 201 and the second member 202 rotate relative to each other. At this time, the rotation (input rotation) generated by the drive source 101 is decelerated at a relatively high reduction ratio in the gear device 1B, and drives the first member 201 or the second member 202 with relatively high torque. That is, the first member 201 and the second member 202 connected by the gear device 1B can bend and extend around the rotation axis Ax1.

More specifically, a first pulley P1 is fixed to the output shaft of the first motor 203. A second pulley P2 is connected to the first pulley P1 via a timing belt T1. Here, the second pulley P2 is fixed to the fixing structure 701 of the bush 70 as a mating member. That is, when the first motor 203 is driven, its rotation is transmitted to the eccentric shaft 7 as an input shaft via the first pulley P1, timing belt T1, and second pulley P2.

Further, the robot joint device 200 further includes a second motor 204. A third pulley P3 is fixed to the output shaft of the second motor 204. A 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 bush 70 and the eccentric shaft 7 through the through hole 73. A fifth pulley P5 is fixed to the end of the shaft 205 on the opposite side from the fourth pulley P4. As a result, when the second motor 204 is driven, its rotation is transmitted to the fifth pulley P5 via the third pulley P3, timing belt T2, fourth pulley P4, and shaft 205.

The robot joint device 200 is used, for example, in a robot such as a horizontal multi-joint robot (SCARA type robot). Further, the robot joint device 200 is not limited to horizontal articulated robots, and may be used, for example, in industrial robots other than horizontal articulated robots, or non-industrial robots. Further, the gear device 1B according to the present embodiment is not limited to the joint device 200 for a robot, and may be used, for example, as a wheel device such as an in-wheel motor, in a vehicle such as an automated guided vehicle (AGV: Automated Guided Vehicle). good.

<Modified example>
Even in the distribution type eccentric oscillating internal meshing planetary gear device as in Embodiment 1, as explained in Embodiment 2, the first gear includes the internal gear 2 and the plurality of second The gears may include a first planetary gear 301 and a second planetary gear 302. In this case, in the distributed type eccentric oscillating internally meshing planetary gear device, the first gear (internal gear 2) meshes with the plurality of second gears (first planetary gear 301 and second planetary gear 302). Different meshing phases occur between the parts when the planetary gear 3 swings.

Further, the gear device 1B may include an inner roller. In other words, in the gear device 1B, it is not essential that each of the plurality of inner pins 4 directly contact the inner circumferential surface 321 of the loose fit hole 32, and each of the plurality of inner pins 4 and the loose fit hole 32 are not necessarily in direct contact with each other. An inner roller may be interposed between them. In this case, the inner roller is attached to the inner pin 4 and is rotatable around the inner pin 4.

The configuration of the second embodiment (including modified examples) can be employed in appropriate combination with the various configurations (including modified examples) described in the first embodiment.

(Embodiment 3)
As shown in FIGS. 23 to 26, the wave gear device 1C (hereinafter also simply referred to as “gear device 1C”) according to the present embodiment includes a rigid internal gear 2C, a flexible external gear 3C, and a wave gear device 1C. It differs from the gear device 1 according to the basic configuration in that it includes a generator 4C.

In the gear device 1C according to the present embodiment, an annular flexible external gear 3C is arranged inside an annular rigid internal gear 2C, and a wave generator is further arranged inside the flexible external gear 3C. 4C is placed. The wave generator 4C partially bends the external teeth 31C of the flexible external gear 3C relative to the internal teeth 21C of the rigid internal gear 2C by bending the flexible external gear 3C into a non-circular shape. Bite together. When the wave generator 4C rotates, the meshing position between the internal teeth 21C and the external teeth 31C moves in the circumferential direction of the rigid internal gear 2C, causing the flexible external gear 3C to interlock with the rigid internal gear 2C. Relative rotation according to the difference in number occurs between both gears (rigid internal gear 2C and flexible external gear 3C). Here, if the rigid internal gear 2C is fixed, the flexible external gear 3C will rotate as the two gears rotate relative to each other. As a result, the flexible external gear 3C provides a rotational output that is reduced at a relatively high reduction ratio in accordance with the difference in the number of teeth between the two gears.

Further, the wave generator 4C that causes the flexible external gear 3C to deflect includes a non-circular cam 41C that is rotationally driven around the input side rotation axis Ax1 and a bearing 42C. . The bearing 42C is arranged between the outer peripheral surface of the cam 41C and the inner peripheral surface 301C of the flexible external gear 3C. The inner ring 422C of the bearing 42C is fixed to the outer peripheral surface of the cam 41C, and the outer ring 421C of the bearing 42C is elastically deformed by being pushed by the cam 41C via a ball-shaped rolling element 423C. Here, as the rolling elements 423C roll, the outer ring 421C can rotate relative to the inner ring 422C, so when the non-circular cam 41C rotates, the rotation of the inner ring 422C is not transmitted to the outer ring 421C, and the cam Wave motion occurs in the external teeth 31C of the flexible external gear 3C pushed by the flexible external gear 41C. As the wave motion of the external tooth 31C occurs, the meshing position between the internal tooth 21C and the external tooth 31C moves in the circumferential direction of the rigid internal gear 2C, as described above, and the position of the meshing position between the internal tooth 21C and the external tooth 31C moves in the circumferential direction of the rigid internal gear 2C. Relative rotation occurs between the internal gear and the internal gear 2C.

In short, in this type of gear device 1C, the wave generator 4C having the bearing 42C deflects the flexible external gear 3C, while transmission of power is realized through meshing between the internal teeth 21C and the external teeth 31C. .

More specifically, a cup-shaped strain wave gearing device is illustrated as an example of the gearing device 1C. That is, the gear device 1C according to the present embodiment uses a flexible external gear 3C formed in a cup shape. The wave generator 4C is combined with the flexible external gear 3C so as to be housed within the cup-shaped flexible external gear 3C.

In the gear device 1C according to the present embodiment, the input side rotation axis Ax1 and the output side rotation axis Ax2 are on the same straight line. In other words, the input side rotation axis Ax1 and the output side rotation axis Ax2 are coaxial. Here, the rotation axis Ax1 on the input side is the rotation center of the wave generator 4C to which input rotation is applied, and the output side rotation axis Ax1 is the rotation center of the flexible external gear 3C that generates output rotation. be. In other words, in the gear device 1C, on the same axis, an output rotation that is reduced at a relatively high reduction ratio with respect to the input rotation is obtained.

The rigid internal gear 2C is also called a circular spline and is an annular component having internal teeth 21C. In this embodiment, the rigid internal gear 2C has an annular shape in which at least the inner circumferential surface is a perfect circle in plan view. Internal teeth 21C are formed on the inner peripheral surface of the annular rigid internal gear 2C along the circumferential direction of the rigid internal gear 2C. The plurality of teeth constituting the internal teeth 21C all have the same shape, and are provided at equal pitches over the entire circumferential area of the inner circumferential surface of the rigid internal gear 2C. In other words, the pitch circle of the internal teeth 21C is a perfect circle in plan view. Moreover, the rigid internal gear 2C has a predetermined thickness in the direction of the rotation axis Ax1. The internal teeth 21C are formed over the entire length of the rigid internal gear 2C in the thickness direction. The tooth traces of the internal teeth 21C are all parallel to the rotation axis Ax1.

The flexible external gear 3C is also referred to as a flex spline, and is an annular component having external teeth 31C. In this embodiment, the flexible external gear 3C is a cup-shaped component made of a relatively thin metal elastic body (metal plate). That is, the flexible external gear 3C has flexibility because its thickness is relatively small (thin). The flexible external gear 3C has a cup-shaped main body 32C. The main body portion 32C has a trunk portion 321C and a bottom portion 322C. The body portion 321C has a cylindrical shape in which at least the inner circumferential surface 301C is a perfect circle in plan view when the flexible external gear 3C is not elastically deformed. The central axis of the body portion 321C coincides with the rotation axis Ax1. The bottom portion 322C is disposed on one opening surface of the body portion 321C and has a disk shape that is a perfect circle in plan view. The bottom portion 322C is disposed on the output side of the rotation axis Ax1 among the pair of opening surfaces of the body portion 321C. As described above, the body portion 32C has a bottomed cylindrical shape, that is, a cup-like shape, which is open to the input side of the rotation axis Ax1 by the body portion 321C and the bottom portion 322C. In other words, the opening surface 35C is formed on the end surface of the flexible external gear 3C on the opposite side to the bottom portion 322C in the direction of the rotation axis Ax1. That is, the flexible external gear 3C has a cylindrical shape with an opening surface 35C on one side of the tooth line direction D1 (in this case, on the input side of the rotation axis Ax1). In this embodiment, the trunk 321C and the bottom 322C are integrally formed from one metal member, thereby realizing a seamless main body 32C.

Here, the wave generator 4C is combined with the flexible external gear 3C so that the non-circular (elliptical) wave generator 4C is fitted inside the body 321C. Thereby, the flexible external gear 3C is elastically deformed into a non-circular shape by receiving an external force from the wave generator 4C in the radial direction (direction perpendicular to the rotation axis Ax1) from the inside to the outside. In this embodiment, the wave generator 4C is combined with the flexible external gear 3C, so that the body portion 321C of the flexible external gear 3C is elastically deformed into an elliptical shape. In other words, a state where the flexible external gear 3C is not elastically deformed means a state where the wave generator 4C is not combined with the flexible external gear 3C. On the other hand, a state where the flexible external gear 3C is elastically deformed means a state where the wave generator 4C is combined with the flexible external gear 3C.

More specifically, the wave generator 4C is fitted into the end of the inner peripheral surface 301C of the body 321C on the side opposite to the bottom 322C (the input side of the rotation axis Ax1). In other words, the wave generator 4C is fitted into the end of the body 321C of the flexible external gear 3C on the side of the opening surface 35C in the direction of the rotation axis Ax1. Therefore, in a state where the flexible external gear 3C is elastically deformed, the flexible external gear 3C has an end on the bottom 322C side at the end on the opening surface 35C side in the direction of the rotation axis Ax1. In comparison, it deforms more greatly and takes on a shape closer to an ellipse. Due to the difference in the amount of deformation in the direction of the rotation axis Ax1, when the flexible external gear 3C is elastically deformed, the inner circumferential surface 301C of the body 321C of the flexible external gear 3C is This includes a tapered surface that is inclined with respect to the rotation axis Ax1.

Furthermore, external teeth 31C are formed along the circumferential direction of the body 321C at least at the end of the outer circumferential surface of the body 321C on the side opposite to the bottom 322C (the input side of the rotation axis Ax1). . In other words, the external teeth 31C are provided at least at the end of the body 321C of the flexible external gear 3C on the side of the opening surface 35C in the direction of the rotation axis Ax1. The plurality of teeth constituting the external tooth 31C all have the same shape, and are provided at equal pitches over the entire circumferential area of the outer peripheral surface of the flexible external gear 3C. That is, the pitch circle of the external teeth 31C becomes a perfect circle in a plan view when no elastic deformation occurs in the flexible external gear 3C. The external teeth 31C are formed only within a certain width from the edge of the body 321C on the opening surface 35C side (input side of the rotation axis Ax1). Specifically, in the direction of the rotation axis Ax1, at least the portion of the body portion 321C into which the wave generator 4C is fitted (the end portion on the opening surface 35C side) has external teeth 31C formed on the outer peripheral surface. . The tooth traces of the external teeth 31C are all parallel to the rotation axis Ax1.

The flexible external gear 3C configured in this way is arranged inside the rigid internal gear 2C. Here, in the flexible external gear 3C, only the end portion of the outer peripheral surface of the body portion 321C on the side opposite to the bottom portion 322C (the input side of the rotation axis Ax1) is inserted inside the rigid internal gear 2C. The rigid internal gear 2C is combined with the rigid internal gear 2C. That is, in the flexible external gear 3C, in the direction of the rotation axis Ax1, the portion of the body portion 321C into which the wave generator 4C is fitted (the end on the opening surface 35C side) is inside the rigid internal gear 2C. inserted into. Here, external teeth 31C are formed on the outer peripheral surface of the flexible external gear 3C, and internal teeth 21C are formed on the inner peripheral surface of the rigid internal gear 2C. Therefore, in a state where the flexible external gear 3C is arranged inside the rigid internal gear 2C, the external teeth 31C and the internal teeth 21C face each other.

Here, the number of internal teeth 21C in the rigid internal gear 2C is greater than the number of external teeth 31C in the flexible external gear 3C by 2N (N is a positive integer). In this embodiment, as an example, N is "1", and the number of teeth (of the external teeth 31C) of the flexible external gear 3C is greater than the number of teeth (of the internal teeth 21C) of the rigid internal gear 2C. ``2'' is too many. The difference in the number of teeth between the flexible external gear 3C and the rigid internal gear 2C defines the reduction ratio of the output rotation to the input rotation in the gear device 1C.

Here, in this embodiment, as an example, the flexible external gear in the direction of the rotation axis Ax1 is arranged such that the center of the external tooth 31C in the tooth trace direction D1 and the center of the internal tooth 21C in the tooth trace direction D1 are opposed to each other. The relative positions of the rigid internal gear 3C and the rigid internal gear 2C are set. That is, the positions of the centers of the external teeth 31C of the flexible external gear 3C and the internal teeth 21C of the rigid internal gear 2C in the tooth trace direction D1 are aligned at the same position in the direction of the rotation axis Ax1. Moreover, in this embodiment, the dimension (tooth width) of the external tooth 31C in the tooth trace direction D1 is larger than the dimension (tooth width) of the internal tooth 21C in the tooth trace direction D1. Therefore, in the direction parallel to the rotation axis Ax1, the internal tooth 21C falls within the range of the tooth trace of the external tooth 31C. In other words, the external teeth 31C protrude in at least one of the tooth trace directions D1 with respect to the internal teeth 21C. In this embodiment, the external teeth 31C protrude both in the tooth trace direction D1 (input side and output side of the rotation axis Ax1) with respect to the internal teeth 21C.

Here, in a state where elastic deformation has not occurred in the flexible external gear 3C (a state where the wave generator 4C is not combined with the flexible external gear 3C), the pitch circle of the external tooth 31C that draws a perfect circle is set to be one size smaller than the pitch circle of the internal teeth 21C, which also draws a perfect circle. That is, when the flexible external gear 3C is not elastically deformed, the external teeth 31C and the internal teeth 21C face each other with a gap therebetween, and do not mesh with each other.

On the other hand, when the flexible external gear 3C is elastically deformed (the wave generator 4C is combined with the flexible external gear 3C), the body 321C has an elliptical shape (non-circular shape). Since it is bent, the external teeth 31C of the flexible external gear 3C partially mesh with the internal teeth 21C of the rigid internal gear 2C. In other words, by elastically deforming the body 321C (at least the end on the opening surface 35C side) of the flexible external gear 3C into an elliptical shape, as shown in FIG. The located external teeth 31C mesh with the internal teeth 21C. In other words, the major axis of the pitch circle of the external tooth 31C, which draws an ellipse, matches the diameter of the pitch circle of the internal tooth 21C, which draws a perfect circle, and the minor axis of the pitch circle of the external tooth 31C, which draws an ellipse, draws a perfect circle. It is smaller than the diameter of the pitch circle of the internal teeth 21C. In this way, when the flexible external gear 3C is elastically deformed, some of the teeth constituting the external teeth 31C are replaced by some of the teeth constituting the internal teeth 21C. It will fit into your teeth. As a result, in the gear device 1C, it becomes possible to mesh a portion of the external teeth 31C with a portion of the internal teeth 21C.

The wave generator 4C is also referred to as a wave generator, and is a component that causes the flexible external gear 3C to deflect and causes the external teeth 31C of the flexible external gear 3C to generate wave motion. In this embodiment, the wave generator 4C is a component whose outer circumferential shape is non-circular, specifically elliptical, in plan view.

By the way, when the flexible external gear 3C is elastically deformed into an elliptical shape, as described above, the external teeth 31C mesh with the internal teeth 21C at two locations on both ends of the elliptical shape in the long axis direction. Become. In this way, at a plurality of meshing sites between the internal teeth 21C and the external teeth 31C, vibrations in the circumferential direction of the rigid internal gear 2C and vibrations in the radial direction of the rigid internal gear 2C may occur due to meshing transmission errors. be. The gear device 1C according to the present embodiment employs the following configuration in order to reduce vibrations occurring in such meshing parts.

That is, the gear device 1C according to the present embodiment includes an annular rigid internal gear 2C having internal teeth 21C, an annular flexible external gear 3C having external teeth 31C, and a wave generator 4C. . The flexible external gear 3C is arranged inside the rigid internal gear 2C. The wave generator 4C is arranged inside the flexible external gear 3C, and causes the flexible external gear 3C to flex. In the gear device 1C, the flexible external gear 3C is deformed as the wave generator 4C rotates about the rotation axis Ax1, and a part of the external tooth 31C meshes with a part of the internal tooth 21C. The flexible external gear 3C is rotated relative to the rigid internal gear 2C according to the difference in the number of teeth between the flexible external gear 3C and the rigid internal gear 2C. Here, different meshing phases occur between the plurality of meshing portions of the internal teeth 21C and the external teeth 31C when the wave generator 4C rotates.

In short, in the second embodiment, different meshing phases are generated between the meshing parts of the first gear (internal gear 2) with the plurality of second gears (planetary gears 3), whereas in this embodiment, the internal gear Mutually different meshing phases are generated between a plurality of meshing portions of the tooth 21C and the external teeth 31C. Regarding the action in this case, the meshing parts of the first gear (internal gear 2) with the plurality of second gears (planetary gears 3) in Embodiment 2 are replaced by the meshing parts of the internal teeth 21C with the external teeth 31C. Since it is the same as when read as , detailed explanation will be omitted. Therefore, according to the gear device 1C according to the present embodiment, it is possible to reduce circumferential vibrations and radial vibrations due to meshing transmission errors at a plurality of meshing sites between the internal teeth 21C and the external teeth 31C.

<Modified example>
The wave generator 4C is not limited to a configuration in which the flexible external gear 3C is elastically deformed into an elliptical shape, but may also be configured to elastically deform the flexible external gear 3C into a triangular or square shape, for example. When the flexible external gear 3C is elastically deformed into a triangular shape, the external teeth 31C mesh with the internal teeth 21C at the three apexes of the triangle, so the external teeth 31C in the internal teeth 21C The structure is such that mutually different meshing phases occur between the three meshing parts. Similarly, when the flexible external gear 3C is elastically deformed into a rectangular shape, the external teeth 31C mesh with the internal teeth 21C at four locations, which are the apexes of the rectangular shape. The structure is such that mutually different meshing phases occur between the four meshing parts with the external teeth 31C.

The configuration of Embodiment 3 (including modified examples) can be employed in appropriate combination with the various configurations (including modified examples) described in Embodiment 1 or Embodiment 2.

(summary)
As explained above, the internal meshing planetary gear device (1, 1A, 1B) according to the first aspect includes an internal gear (2) and a planetary gear (3). The internal gear (2) is held rotatably in an annular gear body (22) and a plurality of inner circumferential grooves (223) formed on the inner circumferential surface (221) of the gear body (22). It has a plurality of outer pins (23) forming teeth (21). The planetary gear (3) has external teeth (31) that partially mesh with internal teeth (21). The internally meshing planetary gear device (1, 1A, 1B) rotates the planetary gear (3) about the rotation axis (Ax1) to rotate the planetary gear (3) relative to the internal gear (2). rotate relative to each other. When the planetary gear (3) swings, mutually different meshing phases occur between the meshing portions of the first gear with the plurality of second gears centered around the rotation axis (Ax1).

According to this aspect, vibrations in the circumferential direction can be suppressed to a smaller level than a configuration without meshing phase, and vibrations in the radial direction can be suppressed smaller than a structure with equal meshing phases. Therefore, there is an advantage that circumferential vibrations and radial vibrations due to meshing transmission errors can be reduced between the first gear and the plurality of second gears.

In the internal meshing planetary gear device (1, 1A, 1B) according to the second aspect, a first planetary gear (301) and a second planetary gear (302) are provided as the planetary gears in the first aspect. . The first gear includes an internal gear (2), and the plurality of second gears include a first planetary gear (301) and a second planetary gear (302).

According to this aspect, a meshing transmission error occurs between the internal gear (2) of the internal meshing planetary gear device (1, 1A, 1B), the first planetary gear (301), and the second planetary gear (302). It is possible to reduce vibrations in the circumferential direction and vibrations in the radial direction.

In the first or second aspect, the internal meshing planetary gear device (1, 1A, 1B) according to the third aspect includes an input gear (501) that rotates around a rotation axis (Ax1), and a plurality of crankshafts. It further includes gears (502A, 502B, 502C). The plurality of crankshaft gears (502A, 502B, 502C) are arranged around the input gear (501) so as to mesh with the input gear (501), and rotate in synchronization with each other when the input gear (501) rotates. This causes the planetary gear (3) to swing. The first gear includes an input gear (501), and the second gear includes a plurality of crankshaft gears (502A, 502B, 502C).

According to this aspect, meshing occurs between the input gear (501) and the plurality of crankshaft gears (502A, 502B, 502C) that constitute the primary reduction mechanism of the internal meshing planetary gear device (1, 1A, 1B). Vibrations in the circumferential direction and vibrations in the radial direction due to transmission errors can be reduced.

In the internal meshing planetary gear device (1, 1A, 1B) according to the fourth aspect, in the third aspect, in the circumferential direction of the input gear (501) among the plurality of crankshaft gears (502A, 502B, 502C). When focusing on a pair of adjacent crankshaft gears (502A, 502B, 502C), the arrangement angle δi around the rotation axis (Ax1) of the pair of crankshaft gears (502A, 502B, 502C) and the input gear ( 501) and the number of teeth Zp of each of the pair of crankshaft gears (502A, 502B, 502C), using an integer n,
δi=(2π/(Zs+Zp))×n
It is expressed as

According to this aspect, compared to the case where parts with different specifications are used for the plurality of crankshaft gears (502A, 502B, 502C) or the plurality of eccentric shafts (7A, 7B, 7C), for example, the cost of parts and the assembly cost are reduced. It is possible to keep it low.

In the internal meshing planetary gear device (1, 1A, 1B) according to the fifth aspect, in any one of the first to fourth aspects, the plurality of second gears are arranged in a virtual circle centered on the rotation axis (Ax1). (Cv1) are arranged at uneven intervals.

According to this aspect, circumferential vibrations and radial vibrations due to meshing transmission errors can be reduced.

The robot joint device (200) according to the sixth aspect is fixed to the internal meshing planetary gear device (1, 1A, 1B) according to any one of the first to fifth aspects and the gear body (22). A first member (201) and a second member (202) that rotates relative to the first member (201) as the planetary gear (3) rotates relative to the internal gear (2). , is provided.

According to this aspect, there is an advantage that circumferential vibrations and radial vibrations due to meshing transmission errors can be reduced between the first gear and the plurality of second gears.

The wave gear device (1C) according to the seventh aspect includes an annular rigid internal gear (2C) having internal teeth (21C) and an annular flexible external gear (3C) having external teeth (31C). and a wave generator (4C). The flexible external gear (3C) is arranged inside the rigid internal gear (2C). The wave generator (4C) is arranged inside the flexible external gear (3C) and causes the flexible external gear (3C) to deflect. In the wave gear device (1C), the flexible external gear (3C) is deformed as the wave generator (4C) rotates around the rotation axis (Ax1), and a part of the external tooth (31C) is deformed. The flexible external gear (3C) is meshed with a part of the internal gear (21C), and the flexible external gear (3C) is set relative to the rigid internal gear (2C) according to the difference in the number of teeth between the rigid internal gear (2C) and the rigid internal gear (2C). Rotate it. When the wave generator (4C) rotates, mutually different meshing phases occur between a plurality of meshing portions of the internal teeth (21C) and the external teeth (31C).

According to this aspect, vibrations in the circumferential direction can be suppressed to a smaller level than a configuration without meshing phase, and vibrations in the radial direction can be suppressed smaller than a structure with equal meshing phases. Therefore, there is an advantage that circumferential vibrations and radial vibrations due to meshing transmission errors can be reduced at a plurality of meshing sites between the internal teeth (21C) and the external teeth (31C).

The configurations according to the second to fifth aspects are not essential to the internal meshing planetary gear device (1, 1A, 1B) and can be omitted as appropriate.

1, 1A, 1B Internal meshing planetary gear device 1C Wave gear device 2 Internal gear 2C Rigid internal gear 3 Planetary gear 3C Flexible external gear 4C Wave generator 21, 21C Internal gear 22 Gear body 23 Outer pin 31 , 31C External tooth 200 Joint device for robot 201 First member 202 Second member 221 Inner circumferential surface (of gear body) 223 Inner circumferential groove 301 First planetary gear (second gear)
302 Second planetary gear (second gear)
501 Input gear (first gear)
502A, 502B, 502C Crankshaft gear (second gear)
Ax1 Rotation axis Cv1 Virtual circle

Claims (7)

An internal gear having an annular gear body and a plurality of outer pins that are held in a rotatable state in a plurality of inner circumferential grooves formed on an inner circumferential surface of the gear body and constitute internal teeth;
a planetary gear having external teeth that partially mesh with the internal teeth,
Rotating the planetary gear relative to the internal gear by swinging the planetary gear around a rotation axis;
When the planetary gear swings, mutually different meshing phases occur between the meshing portions of the first gear with the plurality of second gears centered on the rotation axis;
Internal meshing planetary gear system. A first planetary gear and a second planetary gear are provided as the planetary gear,
The first gear includes the internal gear,
The plurality of second gears include the first planetary gear and the second planetary gear,
The internally meshing planetary gear system according to claim 1. an input gear that rotates around the rotation axis;
further comprising a plurality of crankshaft gears disposed around the input gear so as to mesh with the input gear, and rotating in synchronization with each other to swing the planet gear when the input gear rotates;
the first gear includes the input gear,
The second gear includes the plurality of crankshaft gears,
The internal meshing planetary gear device according to claim 1 or 2. When focusing on a pair of crankshaft gears that are adjacent to each other in the circumferential direction of the input gear among the plurality of crankshaft gears, the arrangement angle δi of the pair of crankshaft gears about the rotation axis and the input gear The number of teeth Zs and the number of teeth Zp of each of the pair of crankshaft gears are determined by using an integer n,
δi=(2π/(Zs+Zp))×n
Represented by
The internally meshing planetary gear system according to claim 3. The plurality of second gears are arranged at unequal intervals on a virtual circle centered on the rotation axis,
The internal meshing planetary gear device according to claim 1 or 2. The internal meshing planetary gear device according to claim 1 or 2,
a first member fixed to the gear body;
a second member that rotates relative to the first member as the planetary gear rotates relative to the internal gear;
Robot joint device. an annular rigid internal gear having internal teeth;
an annular flexible external gear having external teeth and disposed inside the rigid internal gear;
a wave generator disposed inside the flexible external gear to cause the flexible external gear to deflect;
The flexible external gear is deformed as the wave generator rotates about the rotation axis, and a part of the external tooth meshes with a part of the internal tooth to form the flexible external gear. A wave gear device that rotates a gear relative to the rigid internal gear according to a difference in the number of teeth between the gear and the rigid internal gear,
When the wave generator rotates, different meshing phases occur between the plurality of meshing portions of the internal teeth with the external teeth;
Wave gear device.