JP2017044287A - Wave gear transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wave gear transmission device capable of improving tooth bearing.SOLUTION: A wave gear transmission device includes a rigid internal gear having an internal tooth, a flexible external gear 3 having an external tooth 33, and a wave generator. In the wave generator, the flexible external gear 3 is elliptically bent to be partially engaged with the rigid internal gear, and an engagement position is moved in a circumferential direction. The flexible external gear 3 includes a barrel portion 31, and a connection wall 32 connected to a load member. The barrel portion 31 has a first end portion 311 and a second end portion 312 in an axial direction X, and has external teeth 33 on an outer periphery 31a. A pair of tooth surfaces 33a, 33b of the external tooth 33 includes an inclined region A expanded so that a tooth thickness T is gradually increased in a tooth trace direction Y from an end portion 331 in a first tooth trace direction to an end portion 332 in a second tooth trace direction through a central portion YC.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wave gear transmission device.

In a flexibly meshing gear device having a cup-shaped flex spline, as a tooth profile of each tooth of the flex spline, a tooth profile in which end relief processing is applied to a pair of end portions in the streak direction of the tooth surface has been proposed ( For example, see Patent Document 1). In Patent Document 1, the central portion of the tooth surface in the tooth trace direction is a flat surface parallel to the tooth trace direction.
Also, in a cup-shaped flexure gear (flex spline) formed with external teeth that mesh with internal teeth of the fixed internal gear of the speed reducer, teeth are formed on the entire tooth surface of the external teeth toward each end in the tooth line direction. A gear that has been crowned so as to reduce the thickness has been proposed (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 02-066241 Japanese Utility Model Publication No. 62-96148

The cup-shaped flex spline (flexible external gear) includes a body part and a bottom part connected to one end of the body part. For example, a load member such as an output shaft of a speed reducer is connected to the bottom portion. The other end of the body portion forms an open end.
When the wave generator is incorporated inside the flexible external gear, the positional relationship of the external teeth with respect to the internal teeth changes according to the axial position, and when the external teeth and the internal teeth mesh, the one end (bottom side end) The closer to, the closer the tip of the external tooth and the tip of the internal tooth are.

Further, when the flexible external gear receives a torque load from the load member side (the one end side) during driving, the body portion is elastically deformed so that the amount of twist in the rotational direction varies depending on the axial position. To do. Specifically, in the external teeth of the flexible external gear, the deformation amount of the portion close to the one end (bottom side end) is larger than the deformation amount of the portion close to the other end (opening end) of the trunk portion. .
For this reason, there is a problem with the tooth contact such that the tooth tip near the one end of the external tooth interferes with the tooth tip of the corresponding internal tooth of the rigid internal gear, or one-side contact occurs between the tooth surfaces. There is.

  The objective of this invention is providing the wave gear transmission which can improve a tooth contact.

  The invention of claim 1 includes a rigid internal gear (2) having a plurality of internal teeth (21), a first end (311) and a second end (312) in the axial direction (X) and an outer periphery ( 31a) a flexible body including a body (31) having a plurality of external teeth (33) and a connecting wall (32) extending in a radial direction from the first end of the body and connected to a load member. The external external gear (3) and the flexible external gear are arranged inside the flexible external gear, and the flexible external gear is bent into an elliptical shape and partially meshed with the rigid internal gear so as to surround the meshing position. A wave generator (4) that moves in a direction, and each of the external teeth has a first streak direction end (331) on the first end side with respect to a streak direction (Y), and the first A second tooth trace direction end portion (332) on the two end sides, and a pair of tooth surfaces (33a, 33b) of each of the external teeth is the first tooth trace direction with respect to the tooth trace direction. A wave gear transmission device (1) including an inclined region (A) that gradually increases so as to gradually increase the tooth thickness (T) from the end portion in the tooth trace direction to the end portion in the second tooth trace direction through the center portion (YC). )I will provide a.

  In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course.

  According to the first aspect of the present invention, the tooth surface of the outer tooth is closer to the connecting wall side with respect to the inner tooth direction while suppressing interference between the tooth tips of the outer tooth and the inner tooth during high torque transmission. It is possible to suppress the one-side contact at the end portion (particularly the tooth tip) in the first tooth line direction. That is, the tooth contact can be improved so that the external tooth contacts the internal tooth in a wider area including the central portion of the tooth trace direction.

It is a schematic sectional drawing of the wave gear transmission device of one Embodiment of this invention. (A) is a schematic plan view of the principal part of a flexible external gear, (b) is a schematic perspective view of the principal part of a flexible external gear.

Embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of a wave gear transmission device according to an embodiment of the present invention. As shown in FIG. 1, the wave gear transmission device 1 includes a rigid internal gear 2, a flexible external gear 3, a wave generator 4, an input shaft 5, a first end member 6, and a second end member. 7, a first bearing 8, a second bearing 9, and a cross roller bearing 10.

  The input shaft 5 is connected and fixed to a rotation source such as an output shaft of the motor. The first end member 6 is connected and fixed to a first load member (not shown) that provides a rotational load to the first end member 6. The first end member 6 constitutes an output member of the wave gear transmission device 1. The second end member 7 is connected and fixed to a second load member (not shown) that provides a fixed load to the second end member 7. The second load member restrains the second end member 7 from rotating. The wave gear transmission device 1 is used for a speed reducer or a speed increaser.

The first end member 6 and the second end member 7 are spaced apart in the direction of the device axis 1a. The first end member 6 and the second end member 7 are annular members, and the central axes of the first end member 6 and the second end member 7 coincide with the device axis 1a.
The input shaft 5 extends through the centers of the first end member 6 and the second end member 7 in the direction of the device axis 1a. The input shaft 5 is rotatably supported by the inner peripheral surfaces 6a and 7a of the first end member 6 and the second end member 7 via the first bearing 8 and the second bearing 9, respectively. The first bearing 8 and the second bearing 9 are, for example, ball bearings.

The rigid internal gear 2, the flexible external gear 3, the wave generator 4, and the cross roller bearing 10 are sandwiched between the first end member 6 and the second end member 7 with respect to the direction of the apparatus axis 1a. It is. The cross roller bearing 10 includes an outer ring 11, an inner ring 12, and a roller 13.
The rigid internal gear 2 is disposed between the second end member 7 and the inner ring 12 of the cross roller bearing 10 with respect to the direction of the device axis 1a. The second end member 7, the rigid internal gear 2, and the inner ring 12 are connected by a fixing screw 14 so as to be integrally rotatable. A plurality of fixing screws 14 are provided at regular intervals in the circumferential direction of the second end member 7. The rigid internal gear 2 has a plurality of internal teeth 21 on the inner peripheral surface 2a.

The flexible external gear 3 includes a body portion 31 and a connecting wall 32. The trunk portion 31 has a cylindrical shape, and has a first end portion 311 and a second end portion 312 with respect to the direction of the apparatus axis 1a (axial direction X). The first end portion 311 faces the first end member 6. The second end portion 312 faces the second end member 7.
On the outer periphery 31 a of the body portion 31, external teeth 33 that are disposed inside the rigid internal gear 2 and can mesh with the internal teeth 21 of the rigid internal gear 2 are formed.

2A and 2B are a plan view and a perspective view of the main part of the flexible external gear 3, respectively. As shown in FIGS. 2A and 2B, the external teeth 33 are formed in a predetermined length range from the second end 312 of the body portion 31 in the direction of the device axis 1 a (axial direction X). Yes.
The external teeth 33 are related to the tooth trace direction Y (corresponding to the axial direction X), the first tooth trace direction end 331 on the first end 311 side (connecting wall 32 side) of the trunk 31 and the first end of the trunk 31. And a second tooth line direction end portion 332 on the two end portion 312 side.

The pair of tooth surfaces 33a, 33b of the external teeth 33 gradually increase the tooth thickness T from the first tooth line direction end portion 331 toward the second tooth line direction end portion 332 through the center portion YC with respect to the tooth line direction Y. An inclined region A that extends to In FIG. 2B, the inclined area A corresponds to the entire area of each tooth surface 33a.
The tooth thickness T is shown as the tooth thickness at the tip of the tooth (position where the tooth depth is maximized). However, the tooth thickness at any tooth position is gradually increased with respect to the tooth line direction Y from the first tooth line direction end 331 to the second tooth line direction end 332 via the central part YC.

The inclined region A may be formed by a linear inclined surface that is inclined with respect to the tooth line direction Y, or may be formed by an arcuate inclined surface (not shown).
The connecting wall 32 is formed of an annular plate that extends radially outward from the first end 311 of the body portion 31. The connecting wall 32 has an annular boss 34 formed on the outer peripheral edge thereof. That is, the flexible external gear 3 has a top hat shape.

The boss 34 of the connecting wall 32 is sandwiched between the outer ring 11 of the cross roller bearing 10 and the first end member 6 with respect to the direction of the apparatus axis 1a. The first end member 6, the flexible external gear 3, and the outer ring 11 are connected by a fixing screw 15 so as to be integrally rotatable. A plurality of fixing screws 15 are provided at regular intervals in the circumferential direction of the first end member 6.
A gap between the outer peripheral surface 5 a of the input shaft 5 and the inner peripheral surface 6 a of the first end member 6 is sealed with an oil seal 16 that allows relative rotation between the input shaft 5 and the first end member 6. A gap between the outer peripheral surface 5 a of the input shaft 5 and the inner peripheral surface 7 a of the second end member 7 is sealed with an oil seal 17 that allows relative rotation between the input shaft 5 and the second end member 7. The outer ring 11 and the inner ring 12 of the cross roller bearing 10 are sealed with an oil seal 18 that allows relative rotation between the outer ring 11 and the inner ring 12.

The wave generator 4 includes a bearing 41 and an elliptical cam 42. The bearing 41 has flexibility. The elliptical cam 42 is disposed on the inner peripheral side of the bearing 41. The elliptical cam 42 elastically deforms the bearing 41 toward the outer peripheral side.
The bearing 41 includes an inner ring 43, an outer ring 44, a ball 45, and a retainer (not shown). The inner ring 43 and the outer ring 44 are flexible. The ball 45 is sandwiched between the inner ring 43 and the outer ring 44 so as to be able to rotate and revolve.

The retainer holds the balls 45 apart from each other. The bearing 41 has a perfect circle shape when the elliptical cam 42 is not provided.
The elliptical cam 42 is formed integrally with the outer peripheral surface 5 a of the input shaft 5. The elliptical cam 42 may be fixed to the outer peripheral surface 5a of the input shaft 5 by screwing or the like.
The major axis of the elliptical cam 42 is set larger than the inner diameter of the inner ring 43 of the bearing 41, and the minor axis of the elliptical cam 42 is set smaller than the inner diameter of the inner ring 43. For this reason, by arranging the elliptical cam 42 on the inner peripheral side of the inner ring 43, the inner ring 43 is pressed to the outer peripheral side at two locations of the long diameter portion, and the inner ring 43 is elastically deformed into an elliptical shape. As the elliptic cam 42 rotates, the long diameter portion rotates, and the elastically deformed inner ring 43 rotates integrally with the elliptic cam 42.

The outer ring 44 is fixed to the inner peripheral side of the flexible external gear 3 and rotates integrally with the flexible external gear 3. Since the inner ring 43 and the outer ring 44 can rotate independently, the inner ring 43 rotates integrally with the rotation of the elliptical cam 42, and the outer ring 44 is bent into an elliptical shape by the inner ring 43.
As a result, the wave generator 4 bends the flexible external gear 3 into a substantially elliptical shape, and partially engages the rigid internal gear 2 and the flexible external gear 3 at two locations of the long diameter portion thereof. .

That is, the wave generator 4 presses the two radial opposite sides of the flexible external gear 3 toward the outer peripheral side and elastically deforms the outer teeth 33 of the long diameter portion into the internal teeth 21. Engage. And the wave generator 4 makes the flexible external gear 3 and the rigid internal gear 2 differential by moving the meshing position of the flexible external gear 3 and the rigid internal gear 2 in the circumferential direction.
When an input shaft 5 connected to a rotation source (not shown) such as an output shaft of a motor rotates at high speed, it is bent into an elliptic shape by an elliptical wave generator 4 and has internal teeth at two locations in the circumferential direction. The meshing portion of the external teeth 33 meshing with 21 moves in the circumferential direction. Since the number of teeth of the external teeth 33 and the internal teeth 21 are different, relative rotation corresponding to the difference in the number of teeth occurs between the external teeth 33 and the internal teeth 21. This rotation is greatly decelerated compared to the input rotation speed. The decelerated rotation is output from the first end member 6 (output member) connected to the load member and transmitted to the load member (not shown).

According to the present embodiment, in the pair of tooth surfaces 33a and 33b of the external teeth 33 of the flexible external gear 3, the central portion YC is connected to the central portion YC from the first streak direction end 331 on the connecting wall 32 side with respect to the streak direction Y. Then, an inclined region A is provided which expands so as to gradually increase the tooth thickness T toward the second tooth line direction end portion 332.
For this reason, in the movement trajectory of the portion of the external teeth 33 on the first tooth line direction end portion 331 side accompanying the elliptical deformation of the flexible external gear 3, between the tooth tips of the external teeth 33 and the internal teeth 21, A predetermined gap is secured.

  Therefore, when high torque is transmitted, the internal teeth 21 of the rigid internal gear 2 and the external teeth 33 of the flexible external gear 3 are restrained from interfering with each other while preventing interference between the internal teeth 21 of the rigid internal gear 2. It is possible to prevent the tooth surfaces 33a and 33b of the external teeth 33 of the flexible external gear 3 from coming into contact with each other at the first tooth streak direction end portion 331 (particularly the tooth tip) on the connecting wall 32 side with respect to the tooth streak direction Y. it can. That is, the tooth contact can be improved so that the external teeth 33 are in contact with the internal teeth 21 in a wider tooth contact region B including the central portion YC in the tooth line direction Y.

Moreover, the fatigue strength of the tooth base of the external tooth 33 is improved by the improvement of the one-piece contact.
The present invention is not limited to the above-described embodiment. For example, the first end member 6 is connected and fixed to a first load member that provides a fixed load, and the second end member 7 provides a rotational load. The output member may be configured by being connected and fixed to the member.
The flexible external gear 3 may be formed in a cup shape such that the connecting wall 32 extends radially inward from the first end 311 of the body portion 31.

The inclined region A of the pair of tooth surfaces 33a and 33b may not reach the second tooth line direction end portion 332. For example, the pair of tooth surfaces 33a and 33b may be formed in a region inclined in the opposite direction to the inclined region A, for example, by chamfering, in the second tooth line direction end portion 332.
In addition, the present invention can be variously modified within the scope of the claims.

  DESCRIPTION OF SYMBOLS 1 ... Wave gear transmission apparatus, 1a ... Apparatus axis line, 2 ... Rigid internal gear, 2a ... Inner peripheral surface, 3 ... Flexible external gear, 4 ... Wave generator, 5 ... Input shaft, 5a ... Outer peripheral surface, 6 ... 1st end member, 6a ... inner peripheral surface, 7 ... second end member, 7a ... inner peripheral surface, 8 ... first bearing, 9 ... second bearing, 10 ... cross roller bearing, 11 ... outer ring, 12 ... inner ring, DESCRIPTION OF SYMBOLS 13 ... Roller, 21 ... Internal tooth, 31 ... Body part, 31a ... Outer periphery, 32 ... Connection wall, 33 ... External tooth, 34 ... Boss part, 41 ... Bearing, 42 ... Elliptical cam, 43 ... Inner ring, 44 ... Outer ring, 45 ... Ball, 311 ... First end of (body), 312 ... Second end of (body), 331 ... First external end of teeth, 332 ... (external) End of second tooth trace direction, A ... inclined area, B ... tooth contact area, T ... tooth thickness, X ... axial direction, Y ... tooth trace direction, YC ... center of tooth trace direction

Claims (1)

A rigid internal gear having a plurality of internal teeth;
A barrel portion having a first end portion and a second end portion in the axial direction and having a plurality of external teeth on the outer periphery, and a connecting wall extending in a radial direction from the first end portion of the barrel portion and connected to a load member A flexible external gear including: a meshing position that is disposed inside the flexible external gear and is bent into an elliptical shape so as to partially mesh with the rigid internal gear. A wave generator for moving the
Each of the external teeth includes a first streak direction end on the first end side and a second streak direction end on the second end side with respect to the tooth streak direction,
A pair of tooth surfaces of each of the external teeth is inclined such that the tooth thickness gradually increases from the first tooth line direction end part toward the second tooth line direction end part through the center part with respect to the tooth line direction. The wave gear transmission device including the region of.

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