JP6685888B2 - Flexible mesh gear - Google Patents

Description

  The present invention relates to a flexible mesh type gear device.

  A flexible mesh type gear device is known as a gear device that is small and lightweight and that can achieve a high reduction ratio. Conventionally, a vibrating body, a cylindrical external gear having flexibility that is arranged on the outer periphery of the vibrating body and flexibly deformed by the rotation of the vibrating body, and rigidity to internally mesh with the external gear A flexible mesh type gear device is proposed that includes a first internal gear and a second internal gear that is arranged in parallel with the first internal gear and has rigidity to internally mesh with the external gear (for example, patents). Reference 1).

JP, 2013-119919, A

  In a flexible mesh type gear device, when the external gear and the internal gear gear wear due to the load applied to the flexible mesh type gear device, backlash increases and the accuracy of the device incorporating the flexible mesh type gear device increases. This will cause a decline.

  The conventional flexible mesh type gear device described in Patent Document 1 can suppress an increase in backlash due to wear of the external gear or the internal gear. However, as a result of intensive studies by the present inventors, they have come to recognize that there is room for improvement in the conventional flex-meshing gear device in order to suppress an increase in backlash.

  The present invention has been made in view of these circumstances, and an object thereof is to provide a flexural meshing gear device capable of suppressing an increase in backlash due to wear of an external gear or an internal gear.

  In order to solve the above-mentioned problems, a flexible mesh type gear device according to an aspect of the present invention has a vibrating body and flexibility that is arranged on the outer periphery of the vibrating body and is flexibly deformed by rotation of the vibrating body. A flexible mesh type including an external gear, a first internal gear in which the external gear internally meshes, and a second internal gear arranged in parallel with the first internal gear and internally meshing with the external gear In the gear device, at least one of the meshing portion between the external gear and the first internal gear and the meshing portion between the external gear and the second internal gear is axially inner than the first region and the first region. And a second region located at. A gap is provided radially inside the portion of the external gear corresponding to the first region, and the tooth thickness of the external gear has a portion corresponding to the first region in the second region at the same tooth height position. And the tooth height of the external gear is smaller in the portion corresponding to the first region than in the portion corresponding to the second region.

  Another aspect of the present invention is also a flexible mesh type gear device. This device includes a vibrating body, a flexible externally toothed gear that is arranged on the outer periphery of the vibrating body and is flexibly deformed by rotation of the vibrating body, and a first internal gear that internally meshes with the externally toothed gear. And a second internal gear that is arranged in parallel with the first internal gear and that internally meshes with the external gear, which is a flexible meshing gear device, wherein the external gear and the first internal gear mesh with each other. At least one of the portion and the meshing portion of the external gear and the second internal gear has a first region and a second region located axially inward of the first region. A gap is provided on the radially inner side of the portion of the external gear corresponding to the first region, and the tooth thicknesses of the first and second internal gears are larger than those of the portion corresponding to the first region at the same tooth height direction position. Is larger than the portion corresponding to the second region, and the tooth heights of the first and second internal gears are smaller in the portion corresponding to the first region than in the portion corresponding to the second region.

  It should be noted that any combination of the above constituent elements, and those in which the constituent elements and expressions of the present invention are interchanged among methods, devices, systems, etc. are also effective as aspects of the present invention.

  According to the present invention, it is possible to provide a flexible meshing gear device capable of suppressing an increase in backlash due to wear of an external gear or an internal gear.

FIG. 3 is a cross-sectional view showing a flexible mesh type gear device according to an embodiment. 2A and 2B are views showing an external gear of a flexible mesh type gear device according to a comparative example. FIGS. 3A and 3B are schematic diagrams showing how the externally toothed gear and the internally toothed gear of a flexible meshing gear device according to a comparative example mesh with each other. 4A and 4B are views showing the external gear of FIG. 1. It is a perspective view which shows the external gear of FIG. 6 (a) and 6 (b) are schematic views showing a state of meshing between the external gear and the internal gear of FIG. 7A to 7C are diagrams showing an external gear according to a modified example. 8A and 8B are diagrams showing an external gear according to a modification. 9 (a) and 9 (b) are diagrams showing an internal gear of a flexible mesh type gear device according to a modification. 10 (a) and 10 (b) are schematic diagrams showing how the externally toothed gear and the internally toothed gear of a flexible meshing gear device according to a modification are meshed with each other.

  Hereinafter, the same or equivalent constituent elements and members shown in each drawing will be denoted by the same reference numerals, and duplicate description will be appropriately omitted. Further, the dimensions of the members in each drawing are enlarged or reduced as appropriate for easy understanding. Moreover, in each drawing, some of the members that are not important for explaining the embodiment are omitted.

  The flexible mesh type gear device according to the embodiment is suitably used as a speed reduction mechanism that extracts a high-speed rotation output of a motor as a low-speed rotation output. For example, it is preferably used as a speed reducer for an actuator used for a joint part of a robot.

  FIG. 1 is a cross-sectional view showing a flexible mesh type gear device 100 according to an embodiment. The flexible mesh type gear device 100 decelerates the input rotation and outputs it. The flexible meshing gear device 100 includes a vibrating body 110, a bearing 120, an external gear 130, and an internal gear 140.

  The vibrating body 110 is a member extending along the rotation axis R of the flexible meshing gear device 100 (in particular, the internal gear 140), and the cross section orthogonal to the rotation axis R has a substantially elliptical shape. The vibrating body 110 is formed with an input shaft hole 111 centered on the rotation axis R. One end of an input shaft (not shown) is inserted into the input shaft hole 111, and is connected to the vibrating body 110 in the rotational direction by, for example, adhesion, press fitting, or key connection. The other end of the input shaft is connected to a rotary drive source such as a motor. The vibrating body 110 rotates as the input shaft rotates.

  The bearing 120 is a bearing that supports the external gear 130 and includes a first bearing 120a and a second bearing 120b. The first bearing 120a is located on one side (the right side in FIG. 1) of the second bearing 120b in the axial direction (that is, the direction parallel to the rotation axis R). The first bearing 120a includes a first portion 121a of the inner ring member 121, a plurality of first rolling elements 122a, a first cage 123a, and a first outer ring member 124a. The second bearing 120b includes a second portion 121b of the inner ring member 121, a plurality of second rolling elements 122b, a second cage 123b, and a second outer ring member 124b.

  The inner ring member 121 is an annular member and is fitted onto the vibration generator 110. The inner ring member 121 has flexibility and is bent into an elliptical shape when the vibrating body 110 is fitted. The inner ring member 121 is fixed to the vibrating body 110 by adhesion or press fitting, and rotates integrally with the vibrating body 110. The inner ring member 121 is integrally formed as an inner ring member of both the first bearing 120a and the second bearing 120b. The inner ring member 121 may be formed integrally with the vibrating body 110.

  Each of the plurality of first rolling elements 122a has a substantially cylindrical shape, and with the central axis oriented in the axial direction, along the circumferential direction (that is, along the circumference of a circle centered on the rotational axis R and perpendicular to the rotational axis R). Direction) is provided with a space in between. The first rolling element 122a is rotatably held by the first cage 123a and rolls on the outer peripheral surface of the first portion 121a of the inner ring member 121. The 2nd rolling element 122b is comprised similarly to the 1st rolling element 122a. The plurality of second rolling elements 122b are rotatably held by the second cage 123b and roll on the outer peripheral surface of the second portion 121b of the inner ring member 121. Hereinafter, the first rolling element 122a and the second rolling element 122b are collectively referred to as "rolling element 122". The first retainer 123a and the second retainer 123b are also collectively referred to as "retainer 123".

  The first outer ring member 124a surrounds the plurality of first rolling elements 122a. The first outer ring member 124a has flexibility, and when the vibrating body 110 fits into the inner ring member 121, the first outer ring member 124a is bent into an elliptical shape via the first rolling element 122a. When the vibrating body 110 rotates, the first outer ring member 124a continuously bends and deforms in accordance with the shape of the vibrating body 110. The second outer ring member 124b surrounds the plurality of second rolling elements 122b. Like the first outer ring member 124a, the second outer ring member 124b has flexibility, and when the vibrating body 110 fits into the inner ring member 121, the second outer ring member 124b is bent into an elliptical shape via the second rolling element 122b, and is raised. When the vibration body 110 rotates, the vibration body 110 continuously bends and deforms in accordance with the shape of the vibration body 110. The first outer ring member 124a and the second outer ring member 124b are formed as separate bodies. The first outer ring member 124a and the second outer ring member 124b may be integrally formed. Hereinafter, the first outer ring member 124a and the second outer ring member 124b are collectively referred to as "outer ring member 124".

  The external gear 130 is a flexible annular member, and the vibrating body 110 and the bearing 120 are fitted inside thereof. The external gear 130 is bent into an elliptical shape by fitting the vibration generator 110 and the bearing 120. When the vibration generator 110 rotates, the external gear 130 continuously flexes and deforms in accordance with the shape of the vibration generator 110. Specifically, the external gear 130 includes a first external tooth 130a, a second external tooth 130b, and a base material 130c. The first bearing 120a is fitted on the inner peripheral side of the first outer teeth 130a, and the second bearing 120b is fitted on the inner peripheral side of the second outer teeth 130b. The first outer teeth 130a and the second outer teeth 130b are formed on the base material 130c that is a single base material, and have the same number of teeth.

  The internal gear 140 includes a first internal gear 140a and a second internal gear 140b arranged in parallel with the first internal gear 140a. The first internal gear 140a and the second internal gear 140b are formed as separate bodies. The first internal gear 140a is an annular member having rigidity and has first internal teeth 141a on the inner peripheral side. The first inner tooth 141a surrounds the first outer tooth 130a bent in an elliptical shape, and meshes with the first outer tooth 130a in two regions in the longitudinal direction of the vibrator 110. The first internal teeth 141a have more teeth than the first external teeth 130a. For example, the number of teeth of the first internal teeth 141a is larger than that of the first external teeth 130a by "2". A plurality of bolt insertion holes 142a penetrating in the axial direction are formed in the first internal gear 140a, and a fixed wall (not shown) (for example, the first member of the robot) is fixed through the bolt insertion holes 142a. It

  The second internal gear 140b is an annular member having rigidity, and has second internal teeth 141b on the inner peripheral side. The second inner tooth 141b surrounds the second outer tooth 130b bent in an elliptical shape, and meshes with the second outer tooth 130b in two regions in the longitudinal direction of the vibrating body 110. The second internal teeth 141b have the same number of teeth as the second external teeth 130b. A plurality of bolt insertion holes 142b penetrating in the axial direction are formed in the second internal gear 140b, and an output device (not shown) (for example, a second member of the robot) is fixed through the bolt insertion holes 142b. It

  The operation of the flexible meshing gear device 100 configured as described above will be described. Here, the number of first external teeth 130a is 100, the number of second external teeth 130b is 100, the number of first internal teeth 141a is 102, and the number of second internal teeth 141b is 100. The case where the internal gear 140a is in a fixed state will be described as an example.

When the vibrating body 110 rotates due to the rotation of the input shaft in a state where the first outer teeth 130a are meshed with the first inner teeth 141a at two positions in the elliptical long axis direction, the first outer teeth 130a are accordingly rotated. The meshing position between the first internal tooth 141a and the first internal tooth 141a also moves in the circumferential direction. Since the first outer teeth 130a and the first inner teeth 141a have different numbers of teeth, at this time, the first outer teeth 130a rotate relative to the first inner teeth 141a. Since the first internal gear 140a is in the fixed state, the first external teeth 130a will rotate by the amount corresponding to the difference in the number of teeth. That is, the rotation of the vibrating body 110 is significantly decelerated and output to the first external teeth 130a. The reduction ratio is as follows.
Reduction ratio = (number of teeth of the first outer teeth 130a-number of teeth of the first inner teeth 141a) / number of teeth of the first outer teeth 130a = (100-102) / 100
= -1 / 50

  The second outer tooth 130b is formed integrally with the first outer tooth 130a, and therefore rotates integrally with the first outer tooth 130a. Since the second outer teeth 130b and the second inner teeth 141b have the same number of teeth, relative rotation does not occur, and the second outer teeth 130b and the second inner teeth 141b rotate integrally. Therefore, the same rotation as the rotation of the first external teeth 130a is output to the second internal teeth 141b, that is, the second internal gear 140b. As a result, it is possible to take out the output from the second internal gear 140b by reducing the rotation of the vibration generator 110 (input shaft) to -1/50.

  Next, the configuration relating to the engagement between the external gear 130 and the internal gear 140 will be described in more detail. In the following, first, the configuration related to the meshing of the external gear and the internal gear of the flexible mesh type gear device according to the comparative example to be compared with the embodiment will be described, and thereafter, the flexible mesh type according to the embodiment. The configuration relating to the engagement between the external gear 130 and the internal gear 140 of the gear device 100 will be described.

  FIGS. 2A and 2B are diagrams showing an external gear 230 of a flexural mesh type gear device according to a comparative example. FIG. 2A is a diagram of the external gear 230 viewed from the circumferential direction. FIG. 2B is an end view taken along the line AA of FIG. The flexible meshing gear device according to the comparative example has the same configuration as the flexible meshing gear device 100 except that an external gear 230 is provided instead of the external gear 130.

  The external gear 230 includes a first external tooth 230a, a second external tooth 230b, and a base material 230c. The first outer teeth 230a, the second outer teeth 230b, and the base material 230c correspond to the first outer teeth 130a, the second outer teeth 130b, and the base material 130c, respectively.

The first external tooth 230a includes an external tooth end portion 231a and an external tooth central portion 232a. The outer tooth central portion 232a is adjacent to the second outer tooth 230b in the axial direction. The outer tooth end 231a is located farther from the second outer tooth 230b than the outer tooth central portion 232a in the axial direction. In the outer tooth end portion 231a and the outer tooth central portion 232a, the tooth thickness T _e 1 of the outer tooth end portion 231a is the tooth thickness T of the outer tooth central portion 232a at the same tooth height position (that is, the same radial position). It is formed to be larger than _e 2. In this comparative example, the outer tooth central portion 232a is formed such that the tooth thickness T _e 2 is constant in the axial direction at the same tooth height direction position. Further, the outer tooth end portion 231a is formed so that the tooth thickness T _e 1 changes in the axial direction at the same tooth height position. Specifically, in the outer tooth end portion 231a, at the same position in the tooth height direction, the tooth thickness T _e 1 is the smallest at the boundary 235a with the outer tooth central portion 232a, and the axial distance from the outer tooth central portion 232a increases. It is formed so as to linearly increase and become maximum at the end portion 236a.

  Since the external gear 230 is manufactured by gear cutting, increasing the tooth thickness increases the tooth height accordingly. Therefore, the tooth height of the outer tooth end 131a is higher from the boundary 235a toward the outermost end 236a.

The second external tooth 230b includes an external tooth end portion 231b and an external tooth central portion 232b. The outer tooth central portion 232b is adjacent to the first outer tooth 230a in the axial direction. The outer tooth end portion 231b is located farther from the first outer tooth 230a than the outer tooth central portion 232b in the axial direction. The outer tooth central portion 232b and the outer tooth end portion 231b are formed similarly to the outer tooth central portion 232a and the outer tooth end portion 231a of the first outer tooth 230a, respectively. Specifically, in the outer tooth end portion 231b, at the same tooth height direction position, the tooth thickness T _e 1 is the minimum at the boundary 235b with the outer tooth central portion 232b, and the axial distance from the outer tooth central portion 232b increases. It is formed so as to linearly increase and become maximum at the endmost portion 236b.

  Although illustration is omitted, both the first internal gear 140a and the second internal gear 140b are formed so that the tooth thickness is constant in the axial direction.

  FIGS. 3A and 3B are schematic diagrams showing how the externally toothed gear 230 and the internally toothed gear 140 mesh with each other in the flexural meshing gear device according to the comparative example. FIG. 3A shows the meshing state at the start of meshing, and FIG. 3B shows the meshing state when the load applied to the external gear 230 increases. The meshing portion 250a between the first external tooth 230a and the first internal gear 140a includes a first region 251a and a second region 252a located axially inward of the first region 251a. The first region 251a is a contact portion between the external tooth end 231a of the first external tooth 230a and the first internal tooth 141a of the first internal gear 140a, and the second region 252a is the external tooth of the first external tooth 230a. It is a contact portion between the central portion 232a and the first internal teeth 141a of the first internal gear 140a.

  Similarly, the meshing portion 250b between the second external tooth 230b and the second internal gear 140b also includes a first region 251b and a second region 252b located axially inward of the first region 251b. The first region 251b is a contact portion between the outer tooth end 231b of the second outer tooth 230b and the second inner tooth 141b of the second inner gear 140b, and the second region 252b is the center of the outer tooth of the second outer tooth 230b. It is a contact portion between the portion 232b and the second internal tooth 141b of the second internal gear 140b.

  Hereinafter, the external tooth end portion 231a and the external tooth end portion 231b are collectively referred to as "external tooth end portion 231", and the external tooth central portion 232a and the external tooth central portion 232b are collectively referred to as "external tooth central portion 232". Also, the first region 251a and the first region 251b are collectively referred to as "first region 251", and the second region 252a and the second region 252b are collectively referred to as "second region 252".

  A gap 260a is provided between the outer tooth end portion 231a of the first outer tooth 230a and the first outer ring member 124a (see FIG. 3A). The gap 260a is an annular gap that surrounds the rotation axis R, and the width (thickness) in the radial direction increases as the distance from the outer tooth central portion 232a increases in the axial direction. Here, a portion of the first outer ring member 124a that faces the outer tooth end portion 231a in the radial direction is formed such that the outer diameter becomes smaller (that is, the thickness becomes thinner) as the axial distance from the second outer ring member 124b increases. As a result, the gap 260 is provided.

  A gap 260b is also provided between the outer tooth end portion 231b of the second outer tooth 230b and the second outer ring member 124b (see FIG. 3B). The gap 260b is configured similarly to the gap 260a.

  In the flexible mesh type gear device according to the comparative example, as described above, at the same tooth height direction position, the tooth thickness of the outer tooth end 231 corresponding to the first region 251 is the outer tooth corresponding to the second region 252. It is larger than the tooth thickness of the central portion 232. Therefore, in the first region 251, the contact pressure at the start of meshing can be made higher than that in the second region 252. That is, the backlash in the first region 251 can be made smaller than that in the second region 252.

  Further, a gap is provided between the outer tooth end 231 of the outer tooth gear 230 and the outer ring member 124. Therefore, when the load applied to the outer tooth end portion 231 during rotation increases, the outer tooth end portion 231 of the outer tooth gear 230 deforms and escapes into a radially inner gap as shown in FIG. The depth of engagement between the tooth gear 140 and the outer tooth end 231 becomes shallow. As a result, wear of the external tooth end 231 and the internal gear 140 when the load applied to the external tooth end 231 increases during rotation is reduced, and an increase in backlash can be suppressed.

  Here, when the external teeth of the external gear 130 and the internal teeth of the internal gear 140 mesh with each other, the meshing starts from the meshing portion closer to the tooth tip. That is, in the comparative example, the meshing starts from the radially outer portion 253 (the portion surrounded by the dotted line in FIG. 3A) 253 of the first region 251. Therefore, in the flexural meshing gear device according to the comparative example, a large load is locally applied to the portion 253 from the start of meshing until the external gear 130 is deformed and changes to the state of FIG. 3B. As a result, the external gear 130 or the internal gear 140 may be worn. Therefore, in the embodiment, the wear of the external gear 130 and the internal gear 140 is further reduced by devising the configuration of the external gear 130.

  FIGS. 4A and 4B are views showing the external gear 130 of the flexible meshing gear device 100 according to the embodiment. FIG. 4A is a diagram of the external gear 130 viewed from the circumferential direction. FIG. 4B is an end view taken along the line BB of FIG. FIGS. 4A and 4B correspond to FIGS. 2A and 2B. FIG. 5 is a perspective view showing the external gear 130 of the flexible meshing gear device 100 according to the embodiment.

The first external tooth 130a includes an external tooth end portion 131a and an external tooth central portion 132a. The outer tooth central portion 132a is adjacent to the second outer tooth 130b in the axial direction. The outer tooth end portion 131a is located farther from the second outer tooth 130b than the outer tooth central portion 132a in the axial direction. The outer tooth end portion 131a and the outer tooth center portion 132a are formed such that the tooth thickness T _e 1 of the outer tooth end portion 131a is larger than the tooth thickness T _e 2 of the outer tooth center portion 132a at the same tooth height position. To be done. In the present embodiment, the outer tooth central portion 132a is formed so that the tooth thickness T _e 2 is constant in the axial direction at the same tooth height direction position. Further, the outer tooth end 131a is formed so that the tooth thickness T _e 1 changes in the axial direction at the same tooth height direction position. Specifically, in the outer tooth end portion 131a, at the same tooth height direction position, the tooth thickness T _e 1 is the minimum at the boundary 135a with the outer tooth central portion 132a, and the farther away from the outer tooth central portion 132a in the axial direction, the further. It is formed so as to linearly increase and become maximum at the outermost end 136a.

Further, unlike the first outer tooth 230a of the flexural mesh type gear device according to the comparative example, the first outer tooth 130a has a tooth height H _e 1 of the outer tooth end portion 131a that is the tooth height H of the outer tooth central portion 132a. It is formed to be smaller than _e 2. In this embodiment, smaller than the tooth depth _{H e} 2 of tooth depth _{H e} 1 Gasotoha central portion 132a of the outer tooth end portion 131a, and tooth depth _{H e} 1 of the outer tooth end portion 131a is axially It is formed so as to be constant.

The second outer tooth 130b includes an outer tooth end portion 131b and an outer tooth central portion 132b. The outer tooth central portion 132b is adjacent to the first outer tooth 130a in the axial direction. The outer tooth central portion 132b is located farther from the first outer tooth 130a than the outer tooth central portion 132b in the axial direction. The outer tooth end portion 131b and the outer tooth center portion 132b are formed similarly to the outer tooth end portion 131a and the outer tooth center portion 132a of the first outer tooth 130a, respectively. Specifically, in the outer tooth end portion 131b, at the same tooth height direction position, the tooth thickness T _e 1 is the minimum at the boundary 135b with the outer tooth central portion 132b, and the axial distance from the outer tooth central portion 132b increases. It is linearly increased and is formed so as to have a maximum at the endmost portion 136b. Further, the outer tooth end portion 131b is formed so that its tooth height is smaller than that of the outer tooth central portion 132b and that the outer tooth end portion 131b has a constant tooth height in the axial direction.

  In other words, the external gear 130 cuts the external tooth end portions 231 of the external teeth of the external gear 230 of the flexible mesh type gear device according to the comparative example toward the inner side in the radial direction to cut the tooth length of the external tooth end portion. Has a smaller shape.

  FIGS. 6A and 6B are schematic diagrams showing how the external gear 130 and the internal gear 140 of the flexible meshing gear device 100 according to the embodiment mesh with each other. FIG. 6A shows the meshing state at the start of meshing, and FIG. 6B shows the meshing state when the load applied to the external gear 130 increases. FIGS. 6A and 6B correspond to FIGS. 3A and 3B.

  The meshing portion 150a between the first external tooth 130a and the first internal gear 140a includes a first region 151a and a second region 152a located axially inward of the first region 151a. The first region 151a is a contact portion between the external tooth end 131a of the first external tooth 130a and the first internal tooth 141a of the first internal gear 140a, and the second region 152a is the external tooth of the first external tooth 130a. It is a contact portion between the central portion 132a and the first internal teeth 141a of the first internal gear 140a.

  Similarly, the meshing portion 150b between the second external tooth 130b and the second internal gear 140b also includes a first area 151b and a second area 152b located axially inward of the first area 151b. The first region 151b is a contact portion between the external tooth end 131b of the second external tooth 130b and the second internal tooth 141b of the second internal gear 140b, and the second region 152b is the center of the external tooth of the second external tooth 130b. It is a contact portion between the portion 132b and the second internal tooth 141b of the second internal gear 140b.

  Hereinafter, the outer tooth end portion 131a and the outer tooth end portion 131b are collectively referred to as "outer tooth end portion 131", and the outer tooth center portion 132a and the outer tooth center portion 132b are collectively referred to as "outer tooth center portion 132". Also, the first area 151a and the first area 151b are collectively referred to as “first area 151”, and the second area 152a and the second area 152b are collectively referred to as “second area 152”.

  A gap 160a is provided between the outer tooth end 131a of the first outer tooth 130a and the first outer ring member 124a, and a gap 160a is provided between the outer tooth end 131b of the second outer tooth 130b and the second outer ring member 124b. A gap 160b is provided in the space (see FIG. 6A). The gap 160a and the gap 160b are configured in the same manner as the gap 260a and the gap 260b of the flexural mesh type gear device according to the comparative example, respectively.

  In the flexible meshing gear device 100 according to the embodiment, as described above, at the same tooth height direction position, the tooth thickness of the outer tooth end 131 corresponding to the first region 151 corresponds to the second region 152. It is larger than the tooth thickness of the outer tooth central portion 132. Therefore, as in the comparative example, the contact pressure at the start of meshing can be made higher in the first region 151 than in the second region 152. That is, the backlash in the first region 151 can be made smaller than that in the second region 152.

  Further, a gap is provided between the outer tooth end 131 of the outer gear 130 and the outer ring member 124. Therefore, when the load applied to the outer tooth end portion 131 during rotation increases, the outer tooth end portion 131 of the outer tooth gear 130 deforms and escapes into a radially inner gap as shown in FIG. 6B. The depth of engagement between the tooth gear 140 and the outer tooth end 131 becomes shallow. As a result, wear of the external tooth end 131 and the internal gear 140 when the load applied to the external tooth end 131 during rotation is increased is reduced, and an increase in backlash can be suppressed.

  Furthermore, in the flexible meshing gear device 100 according to the embodiment, the external tooth end portion 131 of the external gear 130 is formed to have a tooth height smaller than that of the external tooth central portion 132. As a result, the timing at which the external tooth end portion 131 starts to mesh with the internal gear 140 can be delayed as compared with the flexible meshing gear device according to the comparative example. For example, the timing when the external tooth end portion 131 starts to mesh with the internal gear 140 can be substantially the same as the timing when the external tooth central portion 132 starts to mesh with the internal gear 140. As a result, it is possible to prevent a locally large load from being applied to the first region 151 of the meshing portion 150 as in the comparative example, prevent wear of the external gear 130 and the internal gear 140, and increase backlash. Can be suppressed.

  The configuration and operation of the flexible mesh type gear device according to the embodiment have been described above. It should be understood by those skilled in the art that these embodiments are exemplifications, that various modifications can be made to the combination of the respective constituent elements, and that such modifications are within the scope of the present invention.

(Modification 1)
In the embodiment, the external tooth end portion of each external tooth of the external gear has the smallest tooth thickness T _e 1 at the boundary with the central portion of the external tooth, and linearly increases as the axial distance from the central portion of the external tooth increases. Thus, the case has been described in which it is formed so that it becomes maximum at the outermost end. However, it suffices that the outer tooth end portion has a thicker tooth thickness than the central portion of the outer tooth, and various modifications of the shape of the outer tooth are conceivable.

  7A to 7C are diagrams showing an external gear 130 according to a modification. 7A to 7C correspond to FIG. 2B.

  In FIG. 7A, the outer tooth end portion 131 has the smallest tooth thickness at the boundary 135 with the outer tooth central portion 132, increases non-linearly as it moves axially away from the outer tooth central portion 132, and reaches the outermost portion. It is formed so that it becomes maximum at 136.

  In FIG. 7B, the external tooth end portion 131 has a portion where the tooth thickness is constant in the axial direction. Specifically, the outer tooth end portion 131 has the smallest tooth thickness at the boundary 135 with the outer tooth central portion 132, and linearly increases as it moves away from the outer tooth central portion 132 in the axial direction up to the middle of the axial direction. It is formed so as to be constant in the axial direction from there to the endmost portion 136.

  In FIG. 7C, the outer tooth end portion 131 has the same tooth thickness at the boundary 135 with the outer tooth central portion 132 and the tooth thickness at the outermost end portion 136, that is, the tooth thickness in the axial direction. It is formed so as to be constant.

(Modification 2)
8A and 8B are views showing an external gear 130 according to a modification. 8A and 8B correspond to FIGS. 4A and 4B. In this modification, the outer tooth central portion 132 is formed such that the tooth height of the adjacent portion 137 adjacent to the outer tooth end portion 131 is smaller than the tooth height of the other portion 138. Accordingly, when the tooth tip of the external tooth end portion 231 of the external tooth gear 230 is cut to form the external tooth gear 130, a processing error is absorbed and the overall tooth height of the external tooth end portion 131 is reduced. It can be surely made smaller than the tooth height of the outer tooth central portion 132 (excluding the adjacent portion 137).

(Modification 3)
In the embodiment, the case where both the first outer tooth 130a and the second outer tooth 130b include the outer tooth end portion 131 and the outer tooth central portion 132 has been described, but the present invention is not limited to this. One of the first outer tooth 130a and the second outer tooth 130b may have a configuration in which the outer tooth end portion 131 and the outer tooth central portion 132 are not distinguished. That is, either one of the first outer tooth 130a and the second outer tooth 130b may have a constant tooth height in the axial direction, and may have a constant tooth thickness in the axial direction at the same tooth height position. . In this case, the gap between the outer tooth ends 131 and the outer tooth central portion 132, which is not distinguished, is also unnecessary.

(Modification 4)
The technical ideas of the embodiment and the above-described modified examples may be applied to the internal gear 140 instead of the external gear 130 or in addition to the external gear 130.

  9A and 9B are diagrams showing an internal gear 140 of a flexural mesh type gear device according to a modification. FIG. 9A is a diagram of the internal gear 140 viewed from the circumferential direction. FIG. 9B is an end view taken along the line CC of FIG. 9A. 10 (a) and 10 (b) are schematic diagrams showing how the externally toothed gear 130 and the internally toothed gear 140 mesh with each other in a flexural meshing gear device according to a modification. FIGS. 10A and 10B correspond to FIGS. 6A and 6B.

The first internal tooth 141a of the first internal gear 140a includes an internal tooth end portion 143a and an internal tooth central portion 144a. The inner tooth central portion 144a is adjacent to the second inner tooth 141b in the axial direction. The inner tooth end portion 143a is located farther from the second inner tooth 141b than the inner tooth central portion 144a in the axial direction. The inner tooth end portion 143a and the inner tooth central portion 144a are formed such that the tooth thickness T _i 1 of the inner tooth end portion 143a is larger than the tooth thickness T _i 2 of the inner tooth central portion 144a at the same tooth height position. To be done. The inner tooth central portion 144a is formed so that the tooth thickness T _i 2 is constant in the axial direction at the same tooth height position. The inner tooth end portion 143a is formed so that the tooth thickness T _i 1 changes in the axial direction at the same tooth height direction position. Specifically, at the same tooth height position, the inner tooth end portion 143a has a minimum at the boundary with the inner tooth central portion 144a, and linearly increases as it moves away from the inner tooth central portion 144a in the axial direction, and the maximum. It is formed so that it becomes maximum at the end.

The first inner teeth 141a are formed such that the tooth height H _i 1 of the inner tooth end portion 143a is smaller than the tooth height H _i 2 of the inner tooth central portion 144a (excluding the chamfered portion). In the present embodiment, the tooth height H _i 1 of the inner tooth end portion 143a is smaller than the tooth height H _i 2 of the inner tooth center portion 144a, and the tooth height H _i 1 of the inner tooth end portion 143a is in the axial direction. It is formed so as to be constant.

  The second internal gear 140b includes an internal tooth end portion 143b and an internal tooth central portion 144b. The inner tooth central portion 144b is adjacent to the first inner tooth 141a in the axial direction. The inner tooth end portion 143b is located farther from the first inner tooth 141a than the inner tooth central portion 144b in the axial direction. The inner tooth end portion 143b and the inner tooth center portion 144b are formed similarly to the inner tooth end portion 143a and the inner tooth center portion 144a of the first inner tooth 141a, respectively. Hereinafter, the inner tooth end portion 143a and the inner tooth end portion 143b are collectively referred to as "inner tooth end portion 143", and the inner tooth center portion 144a and the inner tooth center portion 144b are collectively referred to as "inner tooth center portion 144". Also called.

  Although illustration is omitted, both the first outer teeth 130a and the second outer teeth 130b are formed so that the tooth thickness is constant in the axial direction.

  In the flexible mesh type gear device according to this modification, at the same tooth height direction position, the tooth thickness of the inner tooth end portion 143 corresponding to the first region 151 is equal to the tooth thickness of the inner tooth central portion 144 corresponding to the second region 152. Greater than tooth thickness. Therefore, as in the flexural meshing gear device 100 according to the embodiment, the contact pressure at the start of meshing can be made higher in the first region 151 than in the second region 152. That is, the backlash in the first region 151 can be made smaller than that in the second region 152.

  Further, similarly to the embodiment, when the load applied to the outer tooth end portion 131 during rotation increases, the outer tooth end portion 131 of the outer tooth gear 130 deforms as shown in FIG. And the engagement depth between the internal gear 140 and the external tooth end 131 becomes shallow. As a result, wear of the external tooth end 131 and the internal gear 140 when the load applied to the external tooth end 131 during rotation is increased is reduced, and an increase in backlash can be suppressed.

  Furthermore, in the flexural mesh type gear device according to this modification, the tooth height of the inner tooth end portion 143 of the inner tooth gear 140 is formed to be smaller than the tooth height of the inner tooth central portion 144. Thereby, the timing at which the internal tooth end portion 143 starts to mesh with the external gear 130 can be substantially the same as the timing at which the internal tooth central portion 144 starts to mesh with the external gear 130, for example. As a result, it is possible to prevent a locally large load from being applied to the first region 151 of the meshing portion 150 as in the comparative example described above, to prevent the external gear 130 and the internal gear 140 from being worn, and to reduce the backlash. Can be suppressed.

  Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment generated by the combination has the effects of the combined embodiment and the modified examples.

  130 External gear, 130a 1st external tooth, 130b 2nd external tooth, 131a, 131b External tooth end part, 132a, 132b External tooth central part, 140 Internal tooth gear, 140a 1st internal tooth gear, 140b 2nd internal tooth Gear, 141a 1st internal tooth, 141b 2nd internal tooth, 150a, 150b meshing part, 151a, 151b 1st area | region, 152a, 152b 2nd area | region, 100 flexion meshing type gear device.

Claims (6)

A vibrating body, an external toothed gear that is arranged on the outer periphery of the vibrating body and has a flexibility that is flexibly deformed by the rotation of the vibrating body, and a first internal gear that internally meshes with the external toothed gear. And a second internal gear that is arranged in parallel with the first internal gear and that internally meshes with the external gear.
At least one of the meshing portion of the external gear and the first internal gear and the meshing portion of the external gear and the second internal gear is in the first region and inward of the first region in the axial direction. A second region located,
A gap is provided radially inward of a portion of the external gear corresponding to the first region,
The tooth thickness of the external gear is larger in a portion corresponding to the first region than in a portion corresponding to the second region at the same tooth height direction position,
The flexible meshing gear device according to claim 1, wherein a tooth length of the external gear is smaller at a portion corresponding to the first region than at a portion corresponding to the second region. A vibrating body, an external toothed gear that is arranged on the outer periphery of the vibrating body and has a flexibility that is flexibly deformed by the rotation of the vibrating body, and a first internal gear that internally meshes with the external toothed gear. And a second internal gear that is arranged in parallel with the first internal gear and that internally meshes with the external gear.
At least one of the meshing portion of the external gear and the first internal gear and the meshing portion of the external gear and the second internal gear is in the first region and inward of the first region in the axial direction. A second region located,
A gap is provided radially inward of a portion of the external gear corresponding to the first region,
As for the tooth thickness of the first and second internal gears, at the same tooth height direction position, the portion corresponding to the first region is larger than the portion corresponding to the second region,
The flexible meshing gear device according to claim 1, wherein a tooth length of the first and second internal gears is smaller at a portion corresponding to the first region than at a portion corresponding to the second region.   The flexible mesh type gear device according to claim 1 or 2, wherein a tooth height of a portion of the external gear or the first and second internal gears corresponding to the first region is constant.   The tooth height of a portion of the external gear or the first and second internal gears corresponding to the second region is smaller in a portion adjacent to the first region than in other portions. The flexible meshing gear device according to any one of 1 to 3.   The tooth thickness of a portion corresponding to the first region of the external gear or the first and second internal gears increases from the second region side toward the axially outer side. 4. The flexible mesh type gear device according to any one of 4 above.   The tooth thickness of a portion corresponding to the second region of the external gear or the first and second internal gears is constant in the axial direction at the same tooth height direction position. A flexible mesh type gear device according to any one of 1.

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