JP2005308131A - Cup type wave gear device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact cup type wave gear device equipped with a bearing. <P>SOLUTION: A cup type wave gear device 1 has a cylindrical rigid internal gear 2, a cup-like flexible external gear 3 arranged coaxial to the inside of the internal gear 2 and a wave generator 4 fitted to the inside. Both gears 2, 3 are made relatively freely rotatable by a bearing 5 formed by a four contact point ball bearing. The bearing 5 is equipped with an outer ring 51 threaded in and fixed to the internal gear 2 and an internal gear 52 threaded in and fixed to the output shaft 6 integrally formed in a boss 36 of the flexible external gear 3, wherein the internal gear 52 is of a divided type formed by a first divided ring 54 and a second divided ring 55. Since the device requires no member for fixing the inner and outer rings and dispenses with forming a ball inserting hole in the inner and outer rings, the bearing structure can be made compact. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cup-type wave gear device having a bearing that supports a rigid internal gear and a cup-shaped flexible external gear in a relatively rotatable state, and in particular, has a bearing structure that is advantageous for downsizing and compacting. The present invention relates to a cup-type wave gear device provided.

  As a reduction gear, a wave gear device composed of three parts, a rigid internal gear, a flexible external gear, and a wave generator is known. In the wave gear device, a flexible external gear is disposed inside a rigid internal gear, and the flexible external gear is bent in a radial direction by a wave generator and partially meshed with the rigid internal gear. . Generally, the wave generator has an elliptical outline, and the difference in the number of teeth between the two gears is two. When the wave generator is rotated by a motor or the like, the meshing position of both gears moves in the circumferential direction, and both gears rotate relative to each other at a rotational speed corresponding to the difference in the number of teeth. By fixing one gear, a reduced rotation output can be obtained from the other gear.

As a bearing for holding both gears in a relatively rotatable state, a cross roller bearing or a four-point contact ball bearing capable of receiving a moment load is used. For example, a wave gear device including a cross roller bearing is disclosed in Patent Document 1 below. The wave gear device disclosed here is called a cup-type wave gear device in which a cup-shaped flexible external gear is incorporated. Moreover, the inner ring | wheel of a cross roller bearing is fixed to the boss | hub of a flexible external gear by the screw engagement and the driving pin, and the fastening torque between these is raised. On the other hand, a four-point contact ball bearing is disclosed, for example, in Patent Document 2 below.
JP 2000-9191 A JP 2003-97564 A

  Here, in order to reduce the size and size of the cup-type wave gear device, not only the rigid internal gear, the flexible external gear and the wave generator, which are the components, but also the size of the bearing can be reduced. It is necessary to plan. For example, in the case of a small wave gear device having an outer diameter of about 10 to 20 mm, the rolling element insertion hole cannot be formed in the bearing. In some cases, it is not possible to secure a space for attaching a retaining ring for fixing the outer ring or the inner ring.

  An object of the present invention is to propose a cup-type wave gear device having a bearing structure that is advantageous for downsizing and compacting.

In order to solve the above problems, the wave gear device of the present invention is:
A cylindrical rigid internal gear;
A cup-shaped flexible external gear disposed inside the rigid internal gear;
It is fitted inside the flexible external gear, the flexible external gear is bent in the radial direction and partially meshed with the rigid internal gear, and the meshing positions of both gears are moved in the circumferential direction. A wave generator,
A bearing that supports the rigid internal gear and the flexible external gear in a relatively rotatable state;
The bearing includes an outer ring screwed and fixed to the rigid internal gear, and an inner ring screwed and fixed to the flexible external gear, and the inner ring is a split type inner ring composed of first and second split rings. It is characterized by being.

  Here, the rigid internal gear includes a cylindrical member, and has a configuration in which an internal thread portion for screwing and fixing the inner teeth and the outer ring is formed on the inner peripheral surface of the cylindrical member. Can do. The flexible external gear includes a cup-shaped member and an output shaft extending from a boss formed on a bottom surface portion of the cup-shaped member, and the second division of the inner ring is formed on an outer peripheral surface of the output shaft. The thing of the structure in which the external thread part for screwing and fixing a ring | wheel was formed can be used. In this case, the second divided wheel is screwed and fixed to the output shaft in a state where the first divided wheel is sandwiched between the second divided wheel and the boss.

  Further, as the bearing, a four-point contact ball bearing or a cross roller bearing can be used.

  In the cup-type wave gear device of the present invention, the outer ring and the inner ring of the bearing supporting the both gears in a relatively rotatable state can be screwed and fixed to the rigid inner gear and the flexible outer gear, respectively, and A split ring is used. Therefore, it is not necessary to fix the inner and outer rings using another member such as a retaining ring. Moreover, since the inner ring is a split ring, the rolling element can be inserted between the inner and outer rings without requiring a rolling element insertion hole. Therefore, a bearing structure with a small size can be realized.

  Therefore, the cup-type wave gear device can be reduced in size and size. Further, by screwing the inner and outer rings, the bearing can be mounted between the two gears, so that the assembly work of the bearing is simplified.

  A cup-type wave gear device to which the present invention is applied will be described below with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a cup-type wave gear device to which the present invention is applied, FIG. 2 is an end view of its input side, and FIG. 3 is an end view of its output side. Referring to these drawings, the cup-type wave gear device 1 is fitted into a rigid internal gear 2, a cup-shaped flexible external gear 3 disposed coaxially inside the rigid internal gear 2, and the inside thereof. And an elliptical contour wave generator 4. The rigid internal gear 2 and the flexible external gear 3 are freely rotatable relative to each other via a bearing 5. An output shaft 6 is integrally formed with the flexible external gear 3 in a coaxial state.

  The structure of each component will be described in detail. First, the rigid internal gear 2 includes a cylindrical member 21. The cylindrical member 21 has a rectangular outer shape, and a hollow hole extending in the direction of the device axis 1a is formed at the center. The hollow member inner peripheral surface of the cylindrical member 21 has a predetermined length from the end surface 22 on the device output side as a large-diameter inner peripheral surface portion 23, and the other portion as a small-diameter inner peripheral surface portion 24. An annular end face 25 facing the output side is formed between them. Inner teeth 27 are formed along the circumferential direction at a portion of the small-diameter inner peripheral surface portion 24 near the device input side end surface 26. Further, a female threaded portion 28 having a female thread is formed in a range of a predetermined length from the end face 22 on the apparatus output side in the large-diameter inner peripheral surface portion 23. Furthermore, screw holes 22a and 26a for attachment are formed at the four corners of the end faces 22 and 26 of the cylindrical member 21, respectively.

  The cup-shaped flexible external gear 3 includes a flexible cup-shaped member 31 that opens toward the input side, and an outer peripheral surface portion of the cup-shaped member 31 on the opening end side of the cylindrical body portion. External teeth 33 are formed, and the bottom surface portion of the cup-shaped member 31 is a thin annular diaphragm 35 on the outer peripheral side, and a thick boss 36 at the center. An output shaft 6 that extends coaxially from the output-side end surface 36 a of the boss 36 is integrally formed. The output shaft 6 extends beyond the end surface 22 of the cylindrical member 21. The flexible external gear 3 having this configuration is arranged coaxially inside the internal gear 2 with the external teeth 33 facing the internal teeth 27.

  Here, the output shaft 6 has a circular outer peripheral surface portion 61 whose base portion on the boss 36 side has a smaller diameter than the boss 36, and thereby the end surface 36 a on the device output side of the boss 36 becomes an annular end surface. ing. In this example, the position of the end surface 36 a in the direction of the device axis 1 a coincides with the position of the annular end surface 25 formed on the cylindrical member 21 of the internal gear 2. Subsequent to this circular outer peripheral surface portion 61, a slightly smaller-diameter circular outer peripheral surface portion is formed, which is a male screw portion 62 in which a male screw is formed. Following the male screw portion 62, a circular outer peripheral surface portion 64 having a constant outer diameter is formed via an annular recess 63.

  The wave generator 4 is fitted inside the external tooth forming portion of the flexible external gear 3, and the external tooth forming portion is bent into an elliptical shape and is positioned at both ends of the elliptical long axis direction. The outer teeth 33 to be engaged are meshed with the inner teeth 27. The wave generator 4 includes a cam plate 41 having an elliptical contour, a plug 42 on which the cam plate 41 is fixed in a coaxial state, and a wave bearing 43 attached to the outer peripheral surface of the cam plate 41. The wave bearing 43 includes flexible inner and outer rings and balls inserted between them. A shaft hole 42a is formed at the center of the plug 42 so that an input shaft (not shown) can be fitted and fixed. When the wave generator 4 having this configuration rotates, the meshing position of the inner teeth 27 and the outer teeth 33 moves in the circumferential direction. The difference in the number of teeth between the inner teeth 27 and the outer teeth 33 is 2n (n is a positive integer), which is two in this example. Therefore, when the wave generator 4 rotates, a relative rotational motion having a rotational speed corresponding to the difference in the number of teeth is generated between the gears 2 and 3.

  On the other hand, the bearing 5 of this example is a four-point contact ball bearing, and includes an outer ring 51, an inner ring 52, and a ball 53 inserted between them in a rollable state. A circular outer peripheral surface of the outer ring 51 is a male screw portion 51a in which a male screw is formed. The male screw portion 51 a can be screwed into a female screw portion formed in the cylindrical member 21 of the internal gear 2. When the outer ring 51 is screwed into the cylindrical member 21, the outer ring 51 hits the annular end surface 25, and its mounting position is defined.

  The inner ring 52 is a split wheel, and includes a first split wheel 54 located on the device input side and a second split wheel 55 located on the device output side. The circular inner peripheral surface 54 a of the first split ring 54 has an inner diameter dimension capable of fitting the circular outer peripheral surface portion 61 on the base side of the output shaft 6, and is attached to the circular outer peripheral surface portion 61. On the circular inner peripheral surface of the second split ring 55, a portion having a predetermined length from the end on the device input side is a female screw portion 55a in which a female screw is formed, and a portion continuous with the end on the device output side has a small diameter. It is a circular inner peripheral surface portion. The female screw portion 55 a can be screwed into the male screw portion 62 of the output shaft 6.

  The second split wheel 52 having this configuration is screwed and fixed to the output shaft 6. When the first split ring 54 is mounted on the output shaft 6 and the ball 53 is inserted, and the second split ring 55 is screwed and fixed to the output shaft 6, the first split ring 54 is inserted between the annular end surface of the boss and the second split ring 55. A state in which the first and second divided wheels 54 and 55 are fixed to the output shaft 6 is formed in a state where the first divided wheel 54 is sandwiched. Two tool holes 55b are formed on the end face on the device output side of the second split ring 55, and the second split ring 55 can be screwed in using these tool holes 55b. Further, by making the second split ring 55 convex instead of the tool hole 55b, the second split ring 55 can be screwed in using a tool such as a wrench.

  In the cup-type wave gear device 1 of this example configured as described above, the bearing structure that supports both the gears 2 and 3 in a rotatable state can be configured to be small and compact. That is, since the outer ring 51 and the inner ring 52 are screwed and fixed to the output shaft formed integrally with the bosses of the inner gear 2 and the flexible outer gear, respectively, a member for fixing the outer ring 51 and the inner ring 52 is unnecessary. is there. Further, since the split rings 54 and 55 are employed as the inner ring 52, no ball insertion hole is required, and the bearing 6 can be made small. Therefore, according to this example, it is possible to manufacture a small cup-type wave gear device having a maximum outer diameter of about 10 to 20 mm. Such a small cup-type wave gear device is suitable for use as a speed reducer used in a finger joint drive mechanism such as a working robot.

  In this example, a four-point contact ball bearing 6 is used, but a cross roller bearing can be used instead. Even in this case, the inner and outer rings may be screwed and fixed to the inner and outer gears, and the inner ring may be divided.

It is a longitudinal section of a cup type wave gear device to which the present invention is applied. FIG. 2 is an end view on the input side of the apparatus of FIG. 1. It is an end view of the output side of the apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cup type wave gear apparatus 1a Apparatus axis 2 Internal gear 21 Cylindrical member 27 Internal tooth 28 Internal thread part 3 Flexible external gear 31 Cup-shaped member 33 External tooth 36 Boss 4 Wave generator 5 Bearing 51 Outer ring 51a Male thread part 52 Inner ring 53 Ball 54 First split wheel 55 Second split wheel 55a Female thread part 6 Output shaft 61 Circular outer peripheral surface part 62 Male thread part

Claims (3)

A rigid internal gear,
A cup-shaped flexible external gear disposed inside the rigid internal gear;
It is fitted inside the flexible external gear, the flexible external gear is bent in the radial direction and partially meshed with the rigid internal gear, and the meshing positions of both gears are moved in the circumferential direction. A wave generator,
A bearing supporting the rigid internal gear and the flexible external gear in a relatively rotatable state;
The bearing includes an outer ring screwed and fixed to the rigid internal gear, and an inner ring screwed and fixed to the flexible external gear, and the inner ring is a split type inner ring composed of first and second split rings. A cup-type wave gear device. In claim 1,
The rigid internal gear includes a cylindrical member, and an internal thread portion for screwing and fixing the inner teeth and the outer ring is formed on an inner peripheral surface of the cylindrical member.
The flexible external gear includes a cup-shaped member and an output shaft extending from a boss formed on a bottom surface portion of the cup-shaped member, and the second split ring of the inner ring is provided on an outer peripheral surface of the output shaft. The male thread part for screwing and fixing is formed,
A cup-type wave gear device in which the second divided wheel is screwed and fixed to the output shaft in a state where the first divided wheel is sandwiched between the second divided wheel and the boss. In claim 2,
The cup-type wave gear device, wherein the bearing is a four-point contact ball bearing or a cross roller bearing.

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