JP2017223246A - Wave gear transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wave gear transmission having high versatility.SOLUTION: A wave gear transmission 1 includes rigid internal gears 2, 3 having a plurality of internal teeth 21, 31 on its inner periphery, a flexible external gear 4 having a plurality of external teeth 41 on its outer periphery, and a wave generator 6. The wave generator 6 is a planetary transmission mechanism containing an inner ring 61, a flexible outer ring 62 fixed to the flexible external gear 4 and two balls 63. The two balls 63 constitute a planetary member arranged at an opposite position in a radial direction Y between the inner ring 61 and the outer ring 62. The outer ring 62 fitted to the two balls 63 is bent into an elliptical shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wave gear transmission device.

  In a wave gear reducer comprising a rigid internal gear, a flexible external gear, and a wave generator, the wave generator flexes and deforms the flexible external gear into an elliptical shape while the elliptical long diameter portion is rigidly internalized. Engage with gears. As a wave reducer, a structure including an elliptical cam and a flexible bearing bent in an elliptical shape by the cam is usually used. The bearing includes an inner ring, an outer ring, and 23 to 25 balls. However, the number of parts is large and the manufacturing cost is high.

  Thus, a technique using a planetary roller mechanism including two rollers disposed on the outer periphery of the input shaft as a wave generator has been proposed (see, for example, Patent Document 1). In the planetary roller mechanism, a holder that holds the two rollers in parallel with the input shaft and holds the rollers in the rotational direction for the time being is an essential configuration.

JP 2005-54981 A

However, when the planetary roller mechanism of Patent Document 1 is applied to a cup-type or top-hat type wave gear reducer having a cup-shaped or top-hat-shaped flexible external gear, the axial position of the flexible external gear Therefore, the outer ring of the planetary roller mechanism (wave generator) fixed to the flexible external gear is inclined with respect to the input shaft.
For this reason, a skew may occur in the roller, and the rotation of the roller may be locked. Therefore, it is difficult to apply the planetary roller mechanism to a cup type or top hat type wave gear reducer, and the versatility is low.

  An object of the present invention is to provide a highly versatile wave gear transmission device.

  The invention of claim 1 includes a rigid internal gear (2, 3) having a plurality of internal teeth (21, 31) on the inner periphery and a flexible external gear (4) having a plurality of external teeth (41) on the outer periphery. Arranged inside the flexible external gear, the flexible external gear is bent into an elliptical shape and partially meshed with the rigid internal gear, and the meshing position is moved in the circumferential direction (Z). A wave generator (6) for causing the inner ring (61), a flexible outer ring (62) fixed to the flexible outer gear, the inner ring and the outer ring. A planetary transmission mechanism including two balls (63) as planetary members disposed at positions opposed to each other in the radial direction (Y), and the outer ring fitted to the two balls is an ellipse. Provided is a wave gear transmission (1) bent into a shape.

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. The same applies hereinafter.
According to a second aspect of the present invention, the two balls may be held at the facing positions only by the contact pressure with respect to the inner ring and the outer ring.

  The diameter (Bd) of the ball may be equal to or greater than or equal to the axial width (W) of the outer ring (Bd ≧ W).

According to the first aspect of the present invention, since two balls are used as planetary members, there is no fear of locking due to skew as in the case of using rollers as planetary members. It can also be applied to so-called cup-shaped or top-hat shaped flexible external gears, and is highly versatile.
In the invention of claim 2, the two balls are autonomously held at the opposing positions only by the contact pressure against the inner ring and the outer ring. Unlike the planetary roller mechanism, the cage is not an essential configuration, and the structure can be simplified.

  In the invention of claim 3, the axial width of the outer ring can be made equal to or less than the diameter of the ball to achieve axial miniaturization, and versatility can be enhanced.

It is a schematic sectional drawing of the wave gear transmission device of one Embodiment of this invention. (A) And (b) is the typical front view and typical side view of a wave generator which show the state by which the outer ring | bowl was bent by the ellipse by two balls.

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 first rigid internal gear 2, a second rigid internal gear 3, a flexible external gear 4, a wave generator 6, an input shaft 7, One member 8, a second member 9, a cross roller bearing 10, a first bearing 11, and a second bearing 12 are provided. In the present embodiment, the wave gear transmission device 1 is described as being used as a speed reducer, but may be used in a speed increaser.

The first rigid internal gear 2 has an annular shape, and a plurality of first internal teeth 21 are formed on the inner peripheral surface. The second rigid internal gear 3 has an annular shape, and a plurality of second internal teeth 31 are formed on the inner peripheral surface. The first rigid internal gear 2 and the second rigid internal gear 3 are separated in the direction of the device axis 1a (corresponding to the axial direction X of the input shaft 7).
The flexible external gear 4 is a ring-shaped gear disposed inside the first rigid internal gear 2 and the second rigid internal gear 3. Thereby, the wave gear transmission apparatus 1 of this embodiment comprises what is called a flat type wave gear transmission apparatus.

The flexible external gear 4 has a plurality of external teeth 41 arranged in the circumferential direction Z (corresponding to the rotation direction) of the outer periphery 4a. The flexible external gear 4 is made of steel or resin having an HRC hardness of about 45 to 55. The external teeth 41 are partially meshed with the first internal teeth 21 of the first rigid internal gear 2 and the second internal teeth 31 of the second rigid internal gear 3, respectively.
The input shaft 7 constitutes a rotation input element that is connected and fixed to a rotation source such as an output shaft of the motor. The first rigid internal gear 2 constitutes a non-rotatable element that is non-rotatably constrained by the first member 8 that is a fixed member. Further, the second rigid internal gear 3 is connected to the second member 9 that is an output member so as to be integrally rotatable, and constitutes a reduced speed rotation output element. The first member 8 and the second member 9 are annular members, and the central axes of the first member 8 and the second member 9 coincide with the device axis 1a.

The input shaft 7 includes an input shaft main body 70, an intermediate flange 73, and a connection ring 74. The input shaft main body 70, the intermediate flange 73, and the connection ring 74 of the input shaft 7 are integrally formed of a single material. The input shaft main body 70 has one end 71 and the other end 72 in the axial direction X.
The intermediate flange 73 is an annular flange that extends radially outward from the outer periphery of the intermediate portion in the axial direction X of the input shaft main body 70. The connection ring 74 is a cylindrical ring that is concentric with the input shaft main body 70 and has a larger diameter than the input shaft main body 70, and is connected to the outer periphery of the intermediate flange 73. The intermediate flange 73 is coupled to the central portion of the coupling ring 74 in the axial direction X.

  The input shaft main body 70 is a hollow shaft having a central axis along the device axis 1a. The input shaft main body 70 is inserted through the centers of the first member 8 and the second member 9. A first bearing 11 and a second bearing 12 are fitted to one end 71 and the other end 72 of the input shaft main body 70 in the axial direction X, respectively. The input shaft 7 is rotatably supported by the first member 8 and the second member 9 via the first bearing 11 and the second bearing 12, respectively. The 1st bearing 11 and the 2nd bearing 12 consist of ball bearings, for example.

The first member 8 includes a main body 80, a first cylindrical protrusion 81, a second cylindrical protrusion 82, and a third cylindrical protrusion 83. The first cylindrical protrusion 81, the second cylindrical protrusion 82, and the third cylindrical protrusion 83 are formed integrally with the main body 80 and extend concentrically from the main body 80 toward the second member 9 side.
The main body 80 of the first member 8 is an annular plate having a center hole 80a centering on the device axis 1a. The first cylindrical protrusion 81 is disposed around the center hole 80 a of the main body 80. The third cylindrical protrusion 83 is disposed on the outer periphery of the main body 80. The second cylindrical protrusion 82 is disposed in the middle portion of the main body 80 in the radial direction Y.

  The second member 9 includes a main body 90, a first cylindrical protrusion 91, and a second cylindrical protrusion 92. The first cylindrical protrusion 91 and the second cylindrical protrusion 92 are formed integrally with the main body 90 and extend concentrically from the main body 90 toward the first member 8 side. The main body 90 of the second member 9 is an annular plate having a center hole 90a centering on the device axis 1a. The first cylindrical protrusion 91 is disposed around the center hole 90 a of the main body 90. The second cylindrical protrusion 82 is disposed on the outer periphery of the main body 90.

The first bearing 11 is interposed between the outer periphery 71 a of the one end 71 of the input shaft main body 70 and the inner periphery 81 a of the first cylindrical protrusion 81 of the first member 8. The second bearing 12 is interposed between the outer periphery 72 a of the other end 72 of the input shaft main body 70 and the inner periphery 91 a of the first cylindrical protrusion 91 of the second member 9.
The first rigid internal gear 2 is fitted and fixed to the inner periphery 82a of the second cylindrical protrusion 82 of the first member 8 (fixing member). The first rigid internal gear 2 is restrained by the first member 8 so as not to rotate. The second rigid internal gear 3 is fitted to the inner periphery 92a of the second cylindrical protrusion 92 of the second member 9 (output member) and is connected to the second member 9 so as to be integrally rotatable.

The cross roller bearing 10 is interposed between the inner periphery 83 a of the third cylindrical protrusion 83 of the first member 8 and the outer periphery 92 b of the second cylindrical protrusion 92 of the second member 9. The cross roller bearing 10 includes an outer ring 13, an inner ring 14, and a roller 15.
The outer ring 13 is fitted to the inner periphery 83 a of the third cylindrical protrusion 83 of the first member 8. The outer ring 13 is fixed to the third cylindrical protrusion 83 by a fixing member 16 fixed to the end surface 83 b of the third cylindrical protrusion 83. The inner ring 14 is fitted to the outer periphery 92 b of the second cylindrical protrusion 92 of the second member 9. The inner ring 14 is connected to the outer periphery 92b of the second cylindrical protrusion 92 so as to be integrally rotatable by a fixing member 17 fixed to the end surface 92c of the second cylindrical protrusion 92.

The wave generator 6 is a planetary transmission mechanism including an inner ring 61, a flexible outer ring 62, and two balls 63. The inner ring 61 is connected to the input shaft 7 so as to be rotatable together.
The intermediate flange 73 of the input shaft 7 is inserted between the first cylindrical protrusion 81 of the first member 8 and the first cylindrical protrusion 91 of the second member 9. The connection ring 74 connects the input shaft 7 and the inner ring 61 of the wave generator 6 so as to be integrally rotatable. The inner ring 61 is fitted and connected to the outer periphery 74a of the connecting ring 74 so as to be integrally rotatable. The flexible outer ring 62 is fitted and connected to the inner periphery 4b of the flexible external gear 4 so as to be integrally rotatable.

The two balls 63 are disposed at opposing positions in the radial direction Y with the inner ring 61 sandwiched between the inner ring 61 and the outer ring 62 and constitute a planetary member. Each ball 63 is disposed between an inner ring raceway groove 61 b formed on the outer circumference 61 a of the inner ring 61 and an outer ring raceway groove 62 b formed on the inner circumference 62 a of the outer ring 62. The two balls 63 as planetary members can rotate and revolve.
2A and 2B are a schematic front view and a schematic side view of the wave generator 6, respectively. As shown in FIG. 2A, the two balls 63 are held at opposing positions in the radial direction Y only by the contact pressure against the inner ring 61 and the outer ring 62. That is, after the two balls 63 are assembled between the inner ring 61 and the outer ring 62 while being held in position using a jig or the like at the time of assembly, the inner ring 61 and the outer ring 62 Are autonomously held at evenly spaced positions in the circumferential direction Z.

  A diameter larger by an elastic deformation amount δ than the maximum diameter Bd0 (not shown) of a ball that can be inserted between the outer ring 62 having a circular shape (not shown) having a diameter D without being elastically deformed and the inner ring 61 Two balls 63 having Bd (Bd = Bd0 + δ) are fitted between the inner ring 61 and the outer ring 62. As a result, the outer ring 62 is bent into an elliptical shape having a major axis (D + 2 × δ) and a minor axis (D−2 × δ).

As shown in FIG. 2B, the diameter Bd of the ball 63 is equal to or greater than half of the axial width W that is the width of the outer ring 62 in the axial direction X (Bd ≧ 0.5 × W). In the example of FIG. 2B, Bd = 1.2 × W, and the diameter Bd is set larger than the axial width W.
The inner ring 61 rotates integrally with the input shaft 7 and revolves along with the rotation of two balls 63 as planetary members, so that the outer ring 62 has a predetermined reduction ratio R1 with respect to the input shaft 7 (inner ring 61). (For example, R1 = 2 to 10, preferably R1 = 2 to 3).

Further, the outer ring 62 of the wave generator 6 is bent into an elliptical shape by being fitted to the two balls 63, and the flexible outer gear 4 of the flexible outer gear 4 is partially at two locations of the major axis of the ellipse. The external teeth 41 are engaged with the internal teeth 21 and 31 of the corresponding rigid internal gears 2 and 3. The wave generator 6 moves the meshing position of the flexible external gear 4 and each of the rigid internal gears 2 and 3 in the circumferential direction Z.
Here, the number of teeth e1 of the first internal teeth 21 of the first rigid internal gear 2 that is a non-rotatable element, the number of teeth e2 of the second internal teeth 31 of the second rigid internal gear 3 that is a decelerated rotation output element, The number of teeth e3 of the external teeth 41 of the flexible external gear 4 is set as follows, for example.

The number of teeth e1 of the first internal teeth 21 of the first rigid internal gear 2 (non-rotatable element) is smaller than the number of teeth e3 of the external teeth 41 of the flexible external gear 4 by a predetermined tooth number difference Δe. Is set to a number (e3−e1 = Δe).
Further, the number of teeth e2 of the second internal teeth 31 of the second rigid internal gear 3 (decelerated rotation output element) is set equal to the number of teeth e3 of the external teeth 41 of the flexible external gear 4 (e2 = e1). . Since the number of teeth e3 of the external teeth 41 and the number of teeth e1 of the first internal teeth 21 are different, relative rotation according to the difference in the number of teeth (Δe = 2) is caused by the external teeth 41 and the first internal teeth 21. Occurs during.

For example, when Δe = 2 and e1 = 202, e2 = 200, and e3 = 200 are set, the gear transmission unit including the flexible external gear 4, the first rigid internal gear 2, and the second rigid internal gear 3 The reduction ratio R2 is as follows.
R2 = {(e1 * e3) / (e3 * e2)}-1
R2 = (202 × 200) / 200 × 200} −1
R2 = 1/100
The overall reduction ratio R of the wave gear transmission device 1 is obtained by multiplying the reduction ratio R1 of the wave generator 6 (planet transmission mechanism) and the reduction ratio R2 of the gear transmission section (R = R1 × R2).

For example, when the reduction ratio R1 = 2 and R2 = 100, R = 1.
According to this embodiment, since the two balls 63 are used as planetary members, there is no risk of locking due to skew as in the case of using rollers as planetary members. Therefore, although not shown, the present invention can be applied to a cup-type or top-hat type wave gear transmission device using a so-called cup-shaped or top-hat-shaped flexible external gear, and is highly versatile.

Further, the two balls 63 of the wave generator 6 (planet transmission mechanism) are opposed to each other in the radial direction Y across the inner ring 61 only by the contact pressure with respect to the inner ring 61 and the outer ring 62 (that is, equidistant positions in the circumferential direction Z). ) Autonomously. Unlike the planetary roller mechanism, the cage is not an essential configuration, and the structure can be simplified.
Further, by using two large balls 63 having a diameter Bd (Bd ≧ 0.5 × W) equal to or greater than half of the axial width W of the outer ring 62, the outer ring 62 is bent and deformed in an elliptical shape. Is substantially possible.

Further, in the present embodiment using the ball 63, unlike the case of using a roller like a planetary roller mechanism, the axial width W of the outer ring 62 can be made equal to or less than the diameter Bd of the ball 63 ( Bd ≧ W). Thereby, size reduction of the axial direction X can be achieved and versatility can be made high.
The present invention is not limited to the above-described embodiment. For example, the inner ring 61 of the wave generator 6 may be integrally formed with the input shaft 7 from a single material.

In the wave generator 6, a cage (not shown) that holds the two balls 63 equally in the circumferential direction may be used.
Further, if any one of the first rigid internal gear, the second rigid internal gear, and the wave generator is restrained so as not to rotate, and one of the remaining two is a rotation input element and the other is a rotation output element Good. 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, 2 ... 1st rigid internal gear (non-rotatable element), 3 ... 2nd rigid internal gear (deceleration rotation output element), 4 ... Flexible external gear, 6 ... Wave Generator: 7 ... Input shaft (rotational input element), 8 ... first member (fixed member), 9 ... second member (output member), 10 ... cross roller bearing, 21 ... first internal teeth, 31 ... second Internal teeth, 41 ... external teeth, 61 ... inner ring, 62 ... outer ring, 63 ... ball, 70 ... input shaft body, 71 ... one end, 72a ... other end, 71a, 72a ... outer periphery, 73 ... intermediate flange, 74 ... connection ring , 80 ... main body, 81 ... first cylindrical protrusion, 82 ... second cylindrical protrusion, 83 ... third cylindrical protrusion, 90 ... main body, 91 ... first cylindrical protrusion, 92 ... second cylindrical protrusion, Bd ... Diameter (ball), C1 ... Device axis, W ... Axial width, (outer ring), X ... Axial direction, Y ... Radial direction, Z ... Circumferential direction

Claims (3)

A rigid internal gear having a plurality of internal teeth on the inner circumference;
A flexible external gear having a plurality of external teeth on the outer periphery;
A wave generator disposed inside the flexible external gear and flexing the flexible external gear in an elliptical shape to partially mesh with the rigid internal gear to move the meshing position in the circumferential direction; With
The wave generator includes two inner ring, a flexible outer ring fixed to the flexible outer gear, and two planetary members disposed at opposite positions in the radial direction between the inner ring and the outer ring. A wave gear transmission device, wherein the outer ring fitted to the two balls is bent in an elliptical shape.   The wave gear transmission device according to claim 1, wherein the two balls are held at the facing positions only by contact pressure with respect to the inner ring and the outer ring.   3. The wave gear transmission device according to claim 1, wherein a diameter of the ball is equal to or greater than or equal to an axial width of the outer ring.

Images