Gear device and robot

Abstract

The present application relates to gear device and robot, in the plate thickness near the outer peripheral end of diaphragm when the opposite side of boss protruding one side decreases to the boss side, the stress is dispersed and the breakage is inhibited. Gear device (1) has internal gear (2), external gear (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33) of outside tooth (33)

Description

TECHNICAL FIELD

[0001] The present application relates to a gear device, a robot provided with the gear device. BACKGROUND

[0002] In Patent Literature 1, it is disclosed that, in a wave reducer (gear device), an annular boss is provided at an outer peripheral end side of a cap-shaped diaphragm, and a surface on the opposite side of the boss protruding side is gradually reduced in thickness toward the boss side as from the vicinity of the outer peripheral end toward a central portion.

[0003] Patent Literature 1: International Publication No. 2018 / 100701

[0004] In the case where the surface on the opposite side of the boss protruding side is gradually reduced in thickness as from the vicinity of the outer peripheral end toward the central portion in the vicinity of the outer peripheral end of the diaphragm, when the end portion of the boss is located at the back of the position where the reduction starts, there is a problem that stress is concentrated, and the diaphragm is easily broken. SUMMARY

[0005] The gear device includes: an internal gear; an external gear that partially engages with the internal gear and relatively rotates with respect to the internal gear about a rotation axis, the external gear having flexibility; a wave generator that contacts an inner peripheral surface of the external gear to move an engagement position of the internal gear with the external gear in a circumferential direction about the rotation axis, wherein the external gear includes: a cylindrical portion that includes external teeth; a diaphragm that extends to a radial direction outer side of the cylindrical portion on the opposite side of the external teeth; and an annular boss portion that is connected to an outer peripheral end side of the diaphragm, a thickness of the diaphragm being gradually reduced as from the outer peripheral end toward a central portion of the diaphragm in the radial direction, and in a natural state, a first surface on the external teeth side of the diaphragm starts to be inclined with respect to a position at which a surface perpendicular to the rotation axis starts to be inclined, the position being located on the cylindrical portion side in the radial direction compared to an inner peripheral surface of the boss portion.

[0006] The robot includes: a first member; a second member that rotates with respect to the first member; a gear device that transmits a driving force that relatively rotates the second member with respect to the first member; and a driving source that outputs the driving force to the gear device. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a side view showing an outline configuration of a robot to which the embodiment is applied.

[0008] Figure 2 is an exploded perspective view showing a gear device to which the embodiment is applied.

[0009] Figure 3 is a longitudinal sectional view of the gear device.

[0010] Figure 4 is a view showing the meshing state of the teeth of the gear device.

[0011] Figure 5 is a half sectional view when the external gear is cut in a plane including the rotation axis.

[0012] Figure 6 is an enlarged sectional view showing the vicinity of the outer peripheral end of the diaphragm.

[0013] Figure 7 is a view showing the relationship between the tilt start position and the stress applied to the diaphragm.

[0014] BRIEF DESCRIPTION OF DRAWINGS

[0015] 1... gear device, 2... internal gear, 3... external gear, 4... wave generator, 31... cylindrical portion, 32... diaphragm, 33... external tooth, 35... boss portion, 100... robot, 110... base as first member, 120... first arm as second member, 171... motor as drive source, 313... inner peripheral surface of external gear, 326... second surface, 327... first surface, 328... virtual surface as surface perpendicular to rotation axis, 351... inner peripheral surface of boss portion, B... central portion of diaphragm, C... outer peripheral end of diaphragm, Ja... rotation axis, L... distance, P... tilt start position, T... minimum thickness. DETAILED DESCRIPTION

[0016] Figure 1 is a side view showing the outline configuration of the robot 100 to which the present embodiment is applied. Note that, hereinafter, in the drawing surface of Figure 1 , the upper side will be referred to as "upper" and the lower side will be referred to as "lower". Also, in the drawing surface of Figure 1 , the base 110 side will be referred to as "base end side" and the opposite side thereof, i.e., the end effector 150 side will be referred to as "front end side". Also, in the drawing surface of Figure 1 , the up-down direction will be set as "vertical direction" and the left-right direction will be set as "horizontal direction". Also, the direction in which the rotation axis Ja described later extends will be set as "axial direction". Note that, in the present specification, "direction" includes both the direction along one side of the axis and the opposite direction thereof.

[0017] The robot 100 will be described simply.

[0018] Figure 1 The robot 100 shown in the drawing is, for example, a robot used for the work of feeding, removing, carrying, and assembling, etc. of a precision device or a member constituting a precision device. As shown in the drawing, the robot 100 includes a base 110 as a first member, a first arm 120 as a second member, and an end effector 150. Figure 1As shown, the robot 100 has a base 110, a first arm 120, a second arm 130, a work head 140, an end effector 150, and a piping 160. Note that "rotation" includes movement in one direction or bidirectional movement including the opposite direction with respect to a certain center point, and rotation with respect to a certain center point.

[0019] The components of the robot 100 will be described briefly.

[0020] The base 110 is fixed to the ground, not shown, for example, by bolts or the like. Inside the base 110, a control device 190 that controls the robot 100 as a whole is provided. Further, the base 110 is connected to the first arm 120 that is rotatable about a first axis Jl in the vertical direction with respect to the base 110. That is, the first arm 120 is relatively rotatable with respect to the base 110.

[0021] A first drive section 170 is provided inside the base 110. The first drive section 170 has a motor 171 (drive source) that is a first motor such as a servo motor that generates a driving force for rotating the first arm 120, and a gear device 1 that is a first speed reducer that reduces the rotation of the motor 171. The input shaft of the gear device 1 is connected to the rotation axis of the motor 171, and the output shaft 7 Figure 3 ) of the gear device 1 is connected to the first arm 120. Thus, when the motor 171 is driven and the driving force thereof is transmitted to the first arm 120 via the gear device 1, the first arm 120 rotates in the horizontal plane about the first axis Jl.

[0022] The second arm 130 that is rotatable about a second axis J2 with respect to the first arm 120 is connected to the front end portion of the first arm 120. Although not shown, a second drive section having a second motor that generates a driving force for rotating the second arm 130 and a second speed reducer that reduces the rotation of the second motor is provided inside the second arm 130. Further, the second arm 130 rotates in the horizontal plane about the second axis J2 with respect to the first arm 120 by the driving force of the second motor being transmitted to the second arm 130 via the second speed reducer.

[0023] The work head 140 is provided to the front end portion of the second arm 130. The work head 140 has a spline shaft 141 that is inserted through a spline nut, not shown, and a ball screw nut that are coaxially provided to the front end portion of the second arm 130. The spline shaft 141 is rotatable about a third axis J3 with respect to the second arm 130, and is movable in the up-down direction. Figure 1 The work head 140 is provided to the front end portion of the second arm 130. The work head 140 has a spline shaft 141 that is inserted through a spline nut, not shown, and a ball screw nut that are coaxially provided to the front end portion of the second arm 130. The spline shaft 141 is rotatable about a third axis J3 with respect to the second arm 130, and is movable in the up-down direction.

[0024] Although not shown, a rotary motor and a lifting motor are arranged in the second arm 130. The driving force of the rotary motor is transmitted to the spline nut through a driving force transmission mechanism not shown, and when the spline nut is rotated in the forward and reverse directions, the spline shaft 141 is rotated in the forward and reverse directions about the third axis J3 in the vertical direction.

[0025] On the other hand, the driving force of the lifting motor is transmitted to the ball screw nut through a driving force transmission mechanism not shown, and when the ball screw nut is rotated in the forward and reverse directions, the spline shaft 141 is moved up and down.

[0026] The end effector 150 is connected to the front end portion of the spline shaft 141. As the end effector 150, there is no particular limitation, and for example, an end effector that grips a carried object, an end effector that processes a processed object, and the like can be listed.

[0027] A plurality of wirings connected to each electronic component, such as the second motor, the rotary motor, the lifting motor, and the like, arranged in the second arm 130 are routed to the base 110 through the piping 160 that links the second arm 130 and the base 110. Also, the plurality of wirings are routed to the control device 190 provided in the base 110 by being concentrated in the base 110 together with the wirings connected to the motor 171 and the encoder not shown.

[0028] As described above, the robot 100 is provided with: the base 110 as a first member; the first arm 120 as a second member provided so as to be able to rotate with respect to the base 110; the gear device 1 that transmits the driving force from one side to the other side of the base 110 and the first arm 120; and the motor 171 as a driving source that outputs the driving force to the gear device 1.

[0029] Note that the first arm 120 and the second arm 130 can be collectively regarded as "the second member". In addition, the "second member" can include the work head 140 and the end effector 150 in addition to the first arm 120 and the second arm 130.

[0030] In addition, in the present embodiment, the first speed reducer is constituted by the gear device 1, but the second speed reducer can also be constituted by the gear device 1, and in addition, both the first speed reducer and the second speed reducer can be constituted by the gear device 1. In the case where the second speed reducer is constituted by the gear device 1, the first arm 120 can be regarded as "the first member" and the second arm 130 can be regarded as "the second member".

[0031] In addition, in the present embodiment, the motor 171 and the gear device 1 are provided to the base 110, but the motor 171 and the gear device 1 can be provided to the first arm 120. In this case, the output shaft 7 of the gear device 1 can be linked to the base 110. Figure 3 )

[0032] Note that the robot 100 of the present embodiment is exemplified as a horizontal multi-joint robot, but the robot of the present application is not limited thereto, and for example, the number of joints of the robot is arbitrary, and in addition, it can also be applied to a vertical multi-joint robot.

[0033] Figure 2 is an exploded perspective view showing a gear device 1 to which the present embodiment is applied. Figure 3 is a longitudinal sectional view of the gear device 1. Figure 4 is a view showing the meshing state of the teeth of the gear device 1. Note that in each of the following drawings, the dimensions of each part are appropriately exaggerated as necessary for ease of explanation, and the dimensions of each part do not necessarily coincide with the actual dimensions. In addition, in Figure 2 , a portion of the external gear 3 is omitted for ease of illustration, specifically, the diaphragm 32 is omitted.

[0034] The gear device 1 is described.

[0035] Figure 2 The gear device 1 shown is a wave gear device, for example, used as a speed reducer. The gear device 1 has an internal gear 2, an external gear 3 provided on the inner side of the internal gear 2 in a top hat shape and having flexibility, and a wave generator 4 provided on the inner side of the external gear 3 and having a bearing 42. In addition, although not shown, a lubricant such as lubricating oil is appropriately disposed at each part of the gear device 1, specifically, at the meshing portion of the internal gear 2 and the external gear 3, the fitting portion of the external gear 3 and the wave generator 4, and the like.

[0036] One of the internal gear 2, the external gear 3, and the wave generator 4 is connected to the base 110 of the aforementioned robot 100, and the other is connected to the first arm 120 of the aforementioned robot 100. In the present embodiment, the internal gear 2 is fixed to the base 110, the external gear 3 is connected to the first arm 120, and the wave generator 4 is connected to the rotation shaft (omitted from the drawing) of the motor 171. Note that, in detail, the connection of the external gear 3 to the first arm 120 is via the relay member 6 and the output shaft 7.

[0037] With such a configuration, therefore, when the rotation shaft of the motor 171 rotates, the wave generator 4 rotates at the same rotational speed as the rotation shaft of the motor 171. In addition, the internal gear 2 and the external gear 3 have different numbers of teeth from each other, and thus, while the meshing positions of the two move in the circumferential direction, they relatively rotate around the rotation axis Ja due to the difference in the number of teeth. In the present embodiment, the number of teeth of the internal gear 2 is greater than that of the external gear 3, and thus, the external gear 3 can be rotated at a lower rotational speed than the rotational speed of the rotation shaft of the motor 171. That is, a speed reducer that has the wave generator 4 on the input shaft side and the external gear 3 on the output shaft side can be achieved.

[0038] It should be noted that the connection method of the internal gear 2, the external gear 3, and the wave generator 4 is not limited to the aforementioned method. For example, even if the external gear 3 is fixed to the base 110 and the internal gear 2 is connected to the first arm 120, the gear device 1 can still be used as a speed reducer. Furthermore, even if the external gear 3 is connected to the rotating shaft of the motor 171, the gear device 1 can still be used as a speed reducer. In this case, the wave generator 4 can also be fixed to the base 110 and the internal gear 2 can be connected to the first arm 120.

[0039] A brief description of the structure of gear device 1 will be provided.

[0040] like Figures 2 to 4 As shown, the internal gear 2 is a gear composed of a rigid body that does not substantially deflect radially, and is a ring-shaped gear with internal teeth 23. In this embodiment, the internal gear 2 is a spur gear. Therefore, the internal teeth 23 have tooth lines parallel to the rotation axis Ja. It should be noted that the tooth lines of the internal teeth 23 may also be inclined relative to the rotation axis Ja. That is, the internal gear 2 may also be a helical gear or a herringbone gear.

[0041] The external gear 3 is inserted inside the internal gear 2. The external gear 3 is a flexible gear capable of radial bending and deformation, and has external teeth 33 that mesh with the internal teeth 23 of the internal gear 2. Furthermore, the external gear 3 has fewer teeth than the internal gear 2. In this way, a speed reducer can be achieved by having different numbers of teeth for the external gear 3 and the internal gear 2.

[0042] In this embodiment, the external gear 3 is so-called top hat shaped. Figure 3 The axial right end has an open end 34. Here, the external gear 3 has a cylindrical portion 31 that is cylindrical about the rotation axis Ja. The cylindrical portion 31 has an external tooth forming portion 311 that is the portion on the side of the open end 34, and a cylindrical main body portion 312 that is the portion on the opposite side of the open end 34 and has a fixed thickness. It should be noted that external teeth 33 are formed on the portion on the outer peripheral surface side of the external tooth forming portion 311.

[0043] In addition to the cylindrical portion 31, the external gear 3 also has a diaphragm 32 connected to the cylindrical portion 31 and extending outward in the radial direction of the cylindrical portion 31. Furthermore, the external gear 3 has an annular boss portion 35 connected to the diaphragm 32.

[0044] The boss portion 35 of the external gear 3 is fixed to the output shaft 7 connected to the first arm 120 via a fastener such as bolt B1 through the relay member 6. Thus, the first arm 120 is connected to the external gear 3. It should be noted that the method of connecting the output shaft 7 and the external gear 3 is not limited to this.

[0045] like Figure 3 ,Figure 4 As shown, the wave generator 4 is positioned inside the external gear 3 and is capable of rotating around the rotation axis Ja. Figure 4 As shown, the wave generator 4 deforms the cross-section of the external gear 3 into an ellipse or oblong shape with a major axis La and a minor axis Lb, thereby enabling the external teeth 33 to mesh with the internal teeth 23 of the internal gear 2. The external gear 3 and the internal gear 2 can rotate around the same axis Ja and mesh internally and externally with each other.

[0046] As described above, the cylindrical portion 31 of the external gear 3 has an external tooth forming portion 311 and a main body portion 312. The external tooth forming portion 311 is... Figure 3 The portion shown is the end on the side of the opening 34, and is provided with external teeth 33. Furthermore, the main body 312 is the portion of the cylindrical portion 31 located on the diaphragm 32 side. The external tooth forming portion 311 is the portion that generates a large deformation due to corning. Corning refers to the three-dimensional deformation as described below: in Figure 4 At the position of the long axis La, the cylindrical portion 31 extends outward relative to the rotation axis Ja, and at the position of the short axis Lb, the cylindrical portion 31 narrows inward relative to the rotation axis Ja. When the wave generator 4 is engaged with the external gear 3, the external tooth forming portion 311 deforms more than the main body portion 312.

[0047] The wave generator 4 is embedded in the portion of the external gear 3 opposite to the external tooth forming portion 311. The wave generator 4 has a cam 41 and a bearing 42 mounted on the outer periphery of the cam 41. The cam 41 has a shaft portion 411 that rotates about the rotation axis Ja, and a cam portion 412 that protrudes outward from one end of the shaft portion 411. When viewed from the direction along the rotation axis Ja, in Figure 4 In the drawing, the outer peripheral surface of the cam portion 412 is elliptical or oblong, with the vertical direction as the major axis La and the horizontal direction as the minor axis Lb. The bearing 42 is embedded in the cam 41 and includes a flexible inner ring 421 and an outer ring 423; and a plurality of balls 422 disposed between them.

[0048] The inner ring 421 is embedded in the outer peripheral surface of the cam portion 412, and elastically deforms into an ellipse or oblong shape along the outer peripheral surface of the cam portion 412. Consequently, the outer ring 423 also elastically deforms into an ellipse or oblong shape. Figure 3 As shown, the outer peripheral surface of the outer ring 423 abuts against the inner peripheral surface 313 of the cylindrical portion 31. Furthermore, a plurality of balls 422 are held by a retainer (not shown) to maintain a constant spacing between them in the circumferential direction of the inner ring 421.

[0049] Such a wave generator 4 changes the orientation of the cam portion 412 as the cam 41 rotates around the rotation axis Ja, and deforms the outer ring 423 in conjunction therewith. Thereby, the meshing positions of the inner gear 2 and the outer gear 3 to each other are moved in the circumferential direction. At this time, the inner ring 421 is fixedly provided to the outer circumferential surface of the cam portion 412, and thus the deformation mode does not change.

[0050] As shown in FIG. 6, the relay member 6 is configured in a ring shape, and is provided between the inner gear 2 and the diaphragm 32 of the outer gear 3. The relay member 6 is configured of an outer ring 61 fixed to the output shaft 7, an inner ring 62 fixed to the inner gear 2, and a bearing 63 that allows the outer ring 61 to rotate with respect to the inner ring 62. Note that the bearing 63 is a so-called crossed roller bearing that is configured with rollers alternately at angles of +45° and -45° with respect to the rotation axis and that bears both radial and axial loads. The boss portion 35 is fixed to the output shaft 7 via the outer ring 61 by a bolt B1. Figure 3

[0051] In the present embodiment, when the rotation axis of the motor 171 rotates, the wave generator 4 rotates at the same rotation speed as the rotation axis of the motor 171. In addition, the outer gear 3 engaged with the inner gear 2, and the output shaft 7 fixed to the outer gear 3 rotate at a rotation speed lower than that of the rotation axis of the motor 171.

[0052] Figure 5 is a half sectional view when the outer gear 3 is cut by a plane including the rotation axis Ja. Note that in Figure 5 , the illustration of the rotation axis Ja is omitted. Furthermore, Figure 6 is an enlarged sectional view of the vicinity of the outer circumferential end C of the diaphragm 32.

[0053] The outer gear 3 will be described in detail.

[0054] As described above, the cylindrical portion 31 of the outer gear 3 has the outer tooth formation portion 311 having an open end 34 at one end, and the main body portion 312 having a constant thickness between the outer tooth formation portion 311 and the diaphragm 32. The outer teeth 33 are formed in the portion on the outer circumferential surface side of the outer tooth formation portion 311.

[0055] In the present embodiment, the thickness of the main body portion 312 is set to be constant, but for example, the cross-sectional shape of the main body portion 312 can be set to decrease in wall thickness from the diaphragm 32 side toward the outer tooth formation portion 311.

[0056] The diaphragm 32 has a first connecting portion 321 connected to the end portion D of the cylindrical portion 31 and bent, a second connecting portion 322 connected to the inner circumferential surface 351 of the boss portion 35, and a diaphragm main body 323 connected to the first connecting portion 321 and the second connecting portion 322.

[0057] ​In other words, the first connecting portion 321 is continuous with the inner peripheral end A of the diaphragm body 323, and bends along the rotation axis Ja towards the cylindrical portion 31 from an inward direction toward the radial direction. It should be noted that the end D of the cylindrical portion 31 is connected to the first connecting portion 321. The second connecting portion 322 extends outward in the radial direction from the outer peripheral end C of the diaphragm body 323 and is connected to the inner peripheral surface 351 of the boss portion 35. The diaphragm body 323 extends in a radial direction orthogonal to the rotation axis Ja.

[0058] Here, the end D of the cylindrical portion 31 is the part where the first connecting portion 321 begins to bend on the cylindrical portion 31 side. More specifically, the end D of the cylindrical portion 31 is the part where the concave arc 54 of the first connecting portion 321 begins to bend on the cylindrical portion 31 side. The outer peripheral end C of the diaphragm 32 is the part where the second connecting portion 322 begins to bend on the diaphragm body 323 side. The inner peripheral end A of the diaphragm 32 is the part where the first connecting portion 321 begins to bend on the diaphragm body 323 side. More specifically, the inner peripheral end A of the diaphragm 32 is the part where the concave arc 54 of the first connecting portion 321 begins to bend on the diaphragm body 323 side.

[0059] A more detailed explanation of external gear 3 will be provided.

[0060] When observed in cross-section, such as Figure 5 As shown, the outer peripheral surface 314 of the main body 312 of the external gear 3 is defined by an outer straight line 53 extending parallel to the rotation axis Ja, from the portion 51 connected to the external tooth forming portion 311 to the end D of the main body 312. When viewed in cross-section, the inner peripheral surface 313 of the main body 312 is also defined by an inner straight line 52 extending parallel to the rotation axis Ja. Therefore, the main body 312 with a constant thickness is defined by the outer straight line 53 and the inner straight line 52.

[0061] When viewed in cross-section, the outer peripheral surface of the first connecting portion 321 of the diaphragm 32 connected to the main body 312 is defined by a concave arc 54. One end of the concave arc 54 is smoothly connected to the outer straight line 53 at the end point D of the main body 312. When viewed in cross-section, the inner peripheral surface of the first connecting portion 321 is defined by a straight portion 52a of the inner straight line 52 extending beyond the end point D, a convex arc 55 smoothly connected to the straight portion 52a, and a straight portion 56a smoothly connected to the other end of the convex arc 55 and extending outward in the radial direction.

[0062] Here, in the first connecting portion 321, the central position of the connecting portion between the inner peripheral end A and the end end D is set as E. In the first connecting portion 321, the radius of curvature of the outer convex arc 55 is smaller than the radius of curvature of the inner concave arc 54. The thickness of the first connecting portion 321 is the largest at the central position E of the connecting portion, increases from the inner peripheral end A to the central position E of the connecting portion, and decreases from the central position E of the connecting portion to the end end D.

[0063] like Figure 5 , Figure 6 As shown, the first surface 327 is formed by a curved and inclined surface, which is the surface of the cylindrical portion 31 side (external tooth 33 side) of the diaphragm body 323 connected to the first connecting portion 321. When viewed in cross-section, the first surface 327 is defined by a concave curved line 57. It should be noted that in this embodiment, the curved surface is not limited to an arc-shaped curved surface. In this way, by bending and inclining the first surface 327, stress can be dispersed.

[0064] Here, the approximate central portion of the diaphragm body 323 from the inner peripheral end A to the outer peripheral end C is designated as B. In other words, the approximate central portion of the diaphragm 32 (diaphragm body 323) in the radial direction is designated as B. The concave bend 57 is, for example, formed by a concave bend 57a defined from the inner peripheral end A to the central portion B, and a concave bend 57b defined from the central portion B to the outer peripheral end C.

[0065] One end of the concave bend 57a smoothly connects to the concave arc 54 at the inner circumferential end A, and the other end smoothly connects to the concave bend 57b. When viewed in cross-section, the inclined starting point P (described later) Figure 6 The inclined starting portion P is connected to the straight portion 58 of the cylindrical portion 31 side of the defined boss portion 35, and one end of the concave bend 57b is smoothly connected to the concave bend 57a. Furthermore, in this embodiment, the inclined starting portion P ( Figure 6 It is located closer to the rotation axis Ja side than the outer peripheral end C of the diaphragm body 323.

[0066] When viewed in cross-section, such as Figure 5 , Figure 6 As shown, the second surface 326 is defined by a straight portion 56 extending beyond the inner peripheral end A from the end of the straight portion 56a. This second surface 326 serves as the surface opposite to the first surface 327 of the diaphragm body 323 connected to the first connecting portion 321. The straight portion 56 extends along a radial direction orthogonal to the rotation axis Ja to the position of the outer peripheral end C. In other words, as... Figure 6 As shown, the second surface 326 is along a surface perpendicular to the rotation axis Ja. It should be noted that because the second surface 326 is along a surface perpendicular to the rotation axis Ja, the diaphragm 32 is difficult to bend on the second surface 326 side, which ensures the gap between the second surface 326 side and the opposite component.

[0067] The boss portion 35 projects toward the second face 326 side of the diaphragm 32 opposite the first face 327 of the diaphragm 32. In this case, the inner peripheral surface 351 of the boss portion 35 projecting toward the second face 326 side of the diaphragm 32 can be used as a reference when assembling the gear device 1 with the counterpart member.

[0068] The thickness of the diaphragm main body 323 defined by the concave curved line 57 and the straight line portion 56 is thinnest at the central portion B and decreases as it goes from the inner peripheral end A toward the central portion B and as it goes from the outer peripheral end C toward the central portion B.

[0069] When viewed in cross section, the face opposite the face of the cylindrical portion 31 side of the second connecting portion 322 is defined by a concave circular arc 59 smoothly connected at the position of the outer peripheral end C to the end of the straight line portion 56. The other end of the concave circular arc 59 is smoothly connected to the inner peripheral surface 351 of the boss portion 35. The concave circular arc 59 is formed with a predetermined radius of curvature.

[0070] As shown in FIG. 6, the inventors investigated the stress applied to the diaphragm 32. Figure 6 As shown in FIG. 6, the inventors investigated the stress applied to the diaphragm 32.

[0071] Figure 7 is a graph showing the relationship between the inclination start position P and the stress applied to the diaphragm 32. In detail, Figure 7 the radial distance from the inner peripheral surface 351 of the boss portion 35 to the inclination start position P and the stress applied to the diaphragm 32 are shown. Note that the radial distance from the inner peripheral surface 351 of the boss portion 35 to the inclination start position P is set as L.

[0072] As shown in FIG. 6, the inventors investigated the stress applied to the diaphragm 32. Figure 7

[0073] As shown in FIG. 6, the inventors investigated the stress applied to the diaphragm 32. Figure 7 ​As shown, NO. 1 is a case where the distance L is -0.03 mm, and the inclined start position P is recessed toward the boss portion 35 side compared with the inner peripheral surface 351. In this case, the stress is 446 MPa. NO. 2 is a case where the distance L is 0.11 mm, and the inclined start position P is located on the cylinder portion 31 side in the radial direction compared with the inner peripheral surface 351. In this case, the stress is 536 MPa. In addition, NO. 3 is a case where the distance L is 0.83 mm, and the stress is 414 MPa. Further, NO. 4 is a case where the distance L is 0.88 mm, and the stress is 518 MPa.

[0074] Here, when the inclined start position P is aligned with the inner peripheral surface 351 that is the end portion of the boss portion 35, stress is concentrated at the inclined start position P, and thus the diaphragm 32 is easily broken, and thus it is necessary to avoid such a position. Note that, as shown in NO. 1, when the inclined start position P is recessed toward the boss portion 35 side, the thickness of the outer peripheral end C of the diaphragm 32 is thinned, and thus in order to correspond to stress applied to the outer peripheral end C, although it also depends on the actual thickness of the outer peripheral end C, it is at least preferable to be located on the cylinder portion 31 side in the radial direction compared with the inner peripheral surface 351 of the boss portion 35. Further, as shown in Figure 7 As shown, in the cases shown in NO. 3 and NO. 4, the stress is reduced compared with NO. 1 and NO. 2.

[0075] According to the above results, experimental results, and simulation results, and the like, it is determined that the radial direction distance L from the inner peripheral surface 351 of the boss portion 35 to the inclined start position P is preferably 0.15 mm or more and 5.00 mm or less, and more preferably 0.45 mm or more and 2.00 mm or less.

[0076] Further, when the minimum thickness of the diaphragm 32 is set to T, the minimum thickness T is 0.14 mm or more and 0.24 mm or less. Thereby, as a ratio (L / T) of the distance L to the minimum thickness T, it is preferable to be 0.625 or more and 35.7 or less, and more preferably 1.88 or more and 14.3 or less.

[0077] According to the present embodiment, the following effects can be obtained.

[0078] The gear device 1 of the present embodiment has an internal gear 2, an external gear 3, and a wave generator 4. In addition, the external gear 3 has a cylinder portion 31, a diaphragm 32, and a boss portion 35. Further, the thickness of the diaphragm 32 (diaphragm main body 323) decreases as it goes from the outer peripheral end C toward the central portion B in the radial direction of the diaphragm main body 323. In addition, in a natural state, the first face 327 on the outer tooth 33 side of the diaphragm main body 323 is located on the cylinder portion 31 side in the radial direction compared with the inner peripheral surface 351 of the boss portion 35 at the inclined start position P at which the first face 327 starts to be inclined with respect to a plane (virtual plane 328) perpendicular to the rotation axis Ja.

[0079] When the first face 327 of the diaphragm body 323 is bent toward the second face 326 side, the thickness of the diaphragm body 323 decreases as it goes from the outer peripheral end C toward the radial direction center portion B of the diaphragm body 323, for example, when the inner peripheral face 351 of the boss portion 35 aligns with the inclination start portion P, stress is concentrated at the inclination start portion P, and the diaphragm 32 is easily damaged. However, according to the present configuration, the inclination start portion P of the first face 327 is located on the radial direction side of the cylindrical portion 31 compared with the inner peripheral face 351 of the boss portion 35, so stress concentration at the inclination start portion P can be mitigated, and thus damage to the diaphragm 32 can be suppressed.

[0080] In the gear device 1 of the present embodiment, the ratio of the radial direction distance L from the inner peripheral face 351 of the boss portion 35 to the inclination start portion P to the minimum thickness T of the diaphragm 32 is 0.625 or more and 35.7 or less.

[0081] According to this configuration, stress concentration near the outer peripheral end C of the diaphragm 32 can be mitigated, and thus damage to the diaphragm 32 can be suppressed.

[0082] In the gear device 1 of the present embodiment, the ratio of the radial direction distance L from the inner peripheral face 351 of the boss portion 35 to the inclination start portion P to the minimum thickness T of the diaphragm 32 is more preferably 1.88 or more and 14.3 or less.

[0083] According to this configuration, stress concentration near the outer peripheral end C of the diaphragm 32 can be further mitigated, and thus damage to the diaphragm 32 can be further suppressed.

[0084] In the gear device 1 of the present embodiment, the boss portion 35 projects toward the second face 326 side of the diaphragm 32, which is opposite to the first face 327 of the diaphragm 32.

[0085] When the boss portion 35 projects toward the first face 327 side of the diaphragm 32, in the present embodiment, for example, in order to abut against the relay member 6, the cylindrical portion 31 needs to be lengthened, which can cause the gear device 1 to become large. Therefore, by projecting the boss portion 35 toward the second face 326 side of the diaphragm 32, miniaturization can be achieved, and at the same time, when assembling with the member of the other party, the inner peripheral face 351 of the boss portion 35 can be used, and thus the convenience of assembly can be improved.

[0086] In the gear device 1 of the present embodiment, the first face 327 is bent and inclined.

[0087] According to this configuration, since the first face 327 is bent and inclined, stress can be dispersed.

[0088] In the gear device 1 of the present embodiment, the second face 326 is along a face perpendicular to the rotation axis Ja.

[0089] According to this configuration, since the second surface 326 is along a surface perpendicular to the rotation axis Ja, the diaphragm 32 (diaphragm main body 323) is difficult to flex on the second surface 326 side, and thus a gap on the second surface 326 side from the counterpart member can be ensured.

[0090] The robot 100 of the present embodiment is provided with: a first member (the base 110); a second member (the first arm 120) that rotates with respect to the first member (the base 110); the gear device 1 that transmits a driving force that causes the second member (the first arm 120) to relatively rotate with respect to the first member (the base 110); and a driving source (the motor 171) that outputs the driving force to the gear device 1. Note that the first arm 120 and the second arm 130 can be collectively referred to as the "second member". Furthermore, the "second member" can include the work head 140 and the end effector 150 in addition to the first arm 120 and the second arm 130. In addition, the gear device 1 can suppress stress concentration at the tilt start position P, and thus can suppress breakage of the diaphragm 32. Thus, it is possible to provide the robot 100 that improves the reliability of the gear device 1.

Claims

1. A gear arrangement, characterized by Possessing: an internal gear; an external gear that partially meshes with the internal gear and relatively rotates around a rotation axis with respect to the internal gear, the external gear having flexibility; a wave generator that contacts an inner peripheral surface of the external gear to move a meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis, wherein the external gear has a cylindrical portion that possesses external teeth, a diaphragm that extends to a radial direction outer side of the cylindrical portion on opposite sides of the external teeth, and an annular boss portion that is connected to an outer peripheral end side of the diaphragm, a thickness of the diaphragm decreases as it goes from the outer peripheral end toward a central portion in the radial direction of the diaphragm, in a natural state, a first face on the external tooth side of the diaphragm starts to incline with respect to a face perpendicular to the rotation axis at a position on the cylindrical portion side in the radial direction compared to an inner peripheral surface of the boss portion, when a distance between the inner peripheral surface of the boss portion and the position where the first face starts to incline in the radial direction is set as a distance L and a minimum thickness of the diaphragm is set as T, the distance L is 0.15 mm or more and 5.00 mm or less, the minimum thickness T is 0.14 mm or more and 0.24 mm or less, and a ratio of the distance L to the minimum thickness T is 0.625 or more and 35.7 or less.

2. The gear device according to claim 1, wherein a ratio of the distance L to the minimum thickness T of the diaphragm is 1.88 or more and 14.3 or less.

3. The gear device according to claim 1 or 2, wherein the boss portion protrudes toward a second face of the diaphragm on an opposite side of the first face of the diaphragm.

4. The gear device according to claim 1, wherein the first face is curved and inclined.

5. The gear device according to claim 3, wherein the second face is along a face perpendicular to the rotation axis.

6. A robot, characterized in that Possessing: a first member; a second member that rotates with respect to the first member; the gear device according to any one of claims 1 to 5 that transmits a driving force that relatively rotates the second member with respect to the first member; and a driving source that outputs the driving force to the gear device.

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