JP3122529U - Holding device for bearing, bearing and harmonic reducer - Google Patents

Abstract

The cage includes two types of cells. The first type of cells (12) have extensions with axially-retentive holding tabs (13) for the rolling bodies (e.g. balls) of the bearing. The second type of cells (10) do not have axially-retentive ball holders. The cage is single-piece. The axial holders have resilient tabs (13) constructed integrally with the cage. The first and second types of cell are distributed uniformly along the circumference. The second type have an axial opening with cylindrical walls (11a).

Description

  The present invention relates to a bearing cage, and more particularly, to a bearing for a harmonic reduction gear.

  Harmonic reducers (harmonic reducers) are themselves, in particular, U.S. Pat. No. 4,715,247, U.S. Pat. No. 4,840,090, and U.S. Patent Publication No. 2002/0178861. Are known. Harmonic reducers are generally oriented inwardly with a wave generator with an elliptical central core, a flexible gear with external teeth mounted on the wave generator via bearings And a rigid ring with teeth. A flexible gear has a pitch circle diameter slightly smaller than the pitch circle diameter of the ring, and generally has two fewer teeth. The flexible gear is deformed by an elliptical wave generator and meshes with the teeth of the ring by the long axis of the ellipse. Once the wave generator is rotated, the meshing part is moved (displaced) along with the long axis of the ellipse. With each rotation of the wave generator, the flexible gear is moved by an angle corresponding to two teeth with respect to the ring. Harmonic reducers provide good position accuracy, high torque, narrow angular gap, high reduction ratio, and good torsional rigidity.

  A bearing used for a harmonic reduction gear includes an outer ring, an inner ring, and a rolling element attached between the two race rings. At least one of these races is a very thin shaft so that it is elastically deformed in the radial direction and exhibits an elliptical profile of a wave generator to which the at least one race is attached. Has a directional cross section. The follow-up path of the rolling elements is not circular but elliptical as in conventional bearings, so that the rolling elements are accurately moved at the same speed in the circumferential direction by their angular positions. is not. Furthermore, the rolling element has a relative displacement (movement) in the radial direction with respect to the cage having a substantially circular shape. For this reason, it is necessary to give the ball a relatively large degree of freedom in the circumferential direction and the radial direction with respect to the pocket of the cage. U.S. Pat. No. 3,285,099 describes a retainer for a harmonic reducer bearing, which is made of a chemically synthesized material and has a pocket for circumferentially separating the spheres, There is a large circumferential clearance between the spheres and the retainer is held against axial movement by an outer flange relative to the sphere.

  U.S. Pat. No. 4,451,098 describes a bearing holder for a harmonic reducer that gives the ball in the pocket a great degree of freedom of movement. The retainer is held against axial movement on the sphere row by an additional retaining ring secured to the retainer. This device requires that this additional ring be securely fastened to the retainer, in which the annular part of the retainer is housed on one side and the annular part of the additional ring on the opposite side. Therefore, it is relatively complex and large in that it requires a sufficient axial space on each side of the sphere. This device is therefore expensive to manufacture and assemble.

  U.S. Pat. No. 4,715,247 (FIGS. 6 and 7) shows a bearing cage for a harmonic reducer, the cage having a spherical surface separated by a relatively thick wall. It is formed from one member having a pocket. As a result, it will prove difficult to mount the cage on the rolling element, and the circumferential clearance of the sphere in the pocket is not enough for the harmonic reducer to operate satisfactorily. Will prove too low.

  The present invention aims to overcome the disadvantages described above.

US Pat. No. 3,285,099 U.S. Pat. No. 4,451,098 US Pat. No. 4,715,247 US Pat. No. 4,840,090 US Patent Publication No. 2002/0178861

  The present invention is simple and cost-effective, allowing a high degree of clearance of the rolling elements within the pocket of the cage while simultaneously having a low degree of friction between the cage and the rolling element. A cage is provided.

  A holding device for a bearing of a harmonic reducer is a bearing retainer for a harmonic reducer designed to be placed in the bearing to give a circumferential distance between the rolling elements, A plurality of first pockets with means for axially holding the cage on the rolling element and a plurality of second pockets lacking means for axially holding the cage on the rolling element And the holding device is integrally formed. Assembly is particularly easy since only some of the pockets are equipped with means for axial retention. Furthermore, the shape of the cage is particularly simple and the cage is manufactured from a single piece, for example as a single piece. A particularly strong cage can be obtained.

  In one embodiment, the means for holding in the axial direction has at least one elastic tongue. The elastic tongue may be integrally formed with the cage.

  Advantageously, the means for holding in the axial direction has two elastic tongues per first pocket. Each of the two elastic tongues may be attached to one side of the first pocket in the circumferential direction, and the wall portion separates the first pocket from an adjacent pocket. May be supported individually.

  In one embodiment, the first pocket and the second pocket are evenly distributed in the circumferential direction. In this way, it is possible to ensure easy assembly of the cage by means of axial movement and to ensure a sufficiently satisfactory axial retention of the cage on the rolling element after assembly.

  In one embodiment, the second pocket has an axial opening with a cylindrical end. Therefore, the second pocket may have a very reduced friction against the rolling elements to the cage and may provide a high degree of radial and circumferential clearance.

  In one embodiment, the first pocket comprises a substantially spherical wall.

  In one embodiment, the second pocket comprises a substantially cylindrical wall.

  Further, the present invention includes two race rings, a row of rolling elements disposed between the race rings, and an integrally formed cage that maintains a circumferential distance between the rolling elements, The cage includes a plurality of pockets with means for axially holding the cage on the rolling element and a plurality of pockets lacking means for axially holding the cage on the rolling element. The present invention relates to a bearing for a harmonic speed reducer.

  In one embodiment, at least one race is deformable in the radial direction. Further, the two race rings may be deformable in the radial direction. The track ring may be made of a hard material such as iron, while having a thin radial thickness. The degree of ovalization of the raceway ((long elliptical axis−short elliptical axis) / diameter × 100) may be about 2 to 5% of the diameter in a free state. The radial thickness of the raceway may be about 1-5% of the free diameter.

  The present invention also provides a harmonic reducer comprising a wave generator, a ring, a flexible gear meshing with the ring, and a bearing disposed between the flexible gear and the wave generator. It is about. The bearing has an inner ring, an outer ring, a row of rolling elements disposed between the race rings, and a cage for holding the rolling elements, and the outer ring is firmly attached to the flexible gear. The inner ring is firmly fixed to the wave generator. The integrally formed cage lacks a first pocket with means for axially holding the cage on the rolling element and means for axially holding the cage on the rolling element. Second pocket. Each first pocket may be separated from the next first pocket by a plurality of second pockets.

  According to this device, the cage can be easily incorporated into the bearing of the harmonic reducer, and the rolling element can be provided in the cage with a sufficient clearance in the radial direction and the circumferential direction, and at a low level. It can be operated with a degree of friction. This results in cost effective assembly, satisfactory operation, reduced wear and low power consumption.

  The present invention will be better understood from a consideration of the detailed description of several embodiments, given by way of non-limiting examples and illustrated in the accompanying drawings.

  As can be seen from FIGS. 1 and 2, the bearing 1 for the harmonic reducer comprises an inner ring 2, an outer ring 3, a row of rolling elements 4, which in this example is a sphere, and a rolling element 4. And a cage 5 for securing a circumferential distance (gap). The inner ring 2 has a thin radial thickness and takes the shape of a ring having a substantially rectangular cross-section with an annular toroidal raceway 6 on its outer surface. The outer ring 3 is similar to the inner ring 2 and has an annular toroidal raceway 7 on its inner diameter. The inner ring 2 and the outer ring 3 have radial front surfaces that are substantially aligned. Each of the inner ring 2 and the outer ring 3 may be manufactured by an integral molding method by machining a piece of iron material.

  An integrally molded cage 5 that is continuous in the circumferential direction is disposed between the inner ring 2 and the outer ring 3 in the radial direction. The cage 5 has an annular part 8 (see FIG. 1) arranged in the axial direction on one side of the rolling element 4 and a separating finger 9 arranged between the rolling elements 4. (See FIG. 2). The separating finger 9 is formed integrally with the annular part 8 and defines the shape of the pocket 10 in which the rolling element 4 is arranged.

  As can be seen in more detail from FIGS. 3 and 4, the separating finger 9 takes the form of a short protrusion protruding axially with respect to the annular part 8, this short protrusion being The inner surface is aligned with the inner diameter line of the annular part 8 and the outer surface is likewise aligned with the outer surface line of the annular part 8. The separating finger 9 has a lateral surface defining a pocket 10 having a substantially cylindrical wall, the diameter of the cylinder defining the wall of the pocket 10 being greater than the diameter of the rolling element 4. In order to allow the rolling element 4 to move in the radial direction and the circumferential direction with respect to the pocket 10, a large gap is provided in the rolling element 4. The bottom of the pocket 10 is formed by an annular part 8 and is substantially radial.

However, the cage 5 also has a separating finger 11 with a plurality of different parts defining the shape of the pocket 12 with means for holding the rolling element 4 in the axial direction.
In the illustrated embodiment, the retainer has three pockets 12 and separating fingers 11 with six different parts, whereas the number of pockets 10 is sixteen.
The pockets 12 have a substantially spherical overall shape that encloses the rolling elements 4 provided on them.
The pockets 12 are distributed substantially evenly in the circumferential direction so as to ensure a uniform axial retention of the cage 5 on the rolling element 4.
The separating fingers 11 with different parts are likewise defined in the radial direction by the inner diameter and the outer surface of the annular part 8.
A separation finger 11 having a different part has a cylindrical surface 11a on one side so as to form one of the pockets 10 next to the pocket 12 together with the adjacent separation finger 9, On the opposite side, it has a spherical surface so as to form the pocket 12 itself with the separating finger 11 having another adjacent different part.
Separating fingers 11 with different parts have claws 13 facing away from the annular part 8 in the axial direction, the free ends of which are adjacent different parts defining the shape of the same pocket 12 It extends in the circumferential direction toward the nail 13 on the opposite side of the separation finger-like part 11.

  In other words, the two claws 13 that identify the pocket 12 extend towards each other and their free ends are separated by a distance less than the diameter of the rolling element 4. Therefore, the pawl 13 of the pocket 12 can ensure that the retainer 5 is held in an axial position on the rolling element 4 arranged in the pocket 12. The concave inner surface of the claw 13 forms a spherical surface of the pocket 12. On the opposite side, the claw 13 has a convex surface.

  On the side having the cylindrical surface 11 a opposite the nail 13, the separating fingers 11 having different parts also have a generally axial shape and are arranged in the pocket 10 next to the pocket 12. In contrast, it extends by a protrusion 14 that cannot be held axially. The protrusion 14 has an axial length at least equal to the axial length of the claw 13 and can protect the claw 13 when the cage 5 is handled prior to the assembly of the bearing 1. Of course, you may supply the holder | retainer 5 without the protrusion part 14 of an axial direction. The axial protrusions 14 and 13 have an annular thickness (angular distance) with the claw 13 being relatively narrow in the circumferential direction, and therefore the axial pressing force is in the annular shape of the cage 5 in the direction of the rolling element 4. As a result of the claw 13 being separated in the circumferential direction when reaching the part 8, the cage 5 is separated by the recess 15 so as to have a predetermined flexibility that allows the retainer 5 to be fitted into the rolling element 4. Yes.

  In one embodiment, the spherical retention pocket is similar to that used in conventional rigid bearing retainers with a row of spheres, but in the radial direction of the sphere within the retention pocket. There is a larger gap between the sphere and the pocket to allow movement. The holding pockets are open on the inner and outer surfaces and are also open axially on the side away from the annular part 8 so that the cage 5 can be fitted in place. The flat-bottomed cylindrical pocket lacking means for axially holding the cage 5 on the rolling element 4 may have a connecting surface between the flat radial bottom surface and the cylindrical surface. The section has a curvature larger than that of the rolling element 4. Cylindrical pockets are also open on the inner and outer surfaces, and the axial end opposite the toroidal part 8 is also open. The diameter of the cylindrical wall 11 a is larger than the diameter of the rolling element 4.

  The cage fits it into the rolling element, with little risk of accidental disassembly and stays in place by its own means at the same time, while at the same time during the operation of the bearing in the harmonic reducer, It can be easily assembled by allowing the possibility of continuous relative movement of the rolling elements and the cage in the circumferential and radial directions.

  In the harmonic reduction gear, the inner ring 2 of the bearing 1 is attached to a wave generator having an elliptical outline. Therefore, the inner ring 2 is ovalized as a result of the fitting and also tries to ovalize the outer ring 3. The inner ring 2 and the outer ring 3 may be manufactured from a steel type selected to withstand such deformation. The outer ring 3 supports, in the radial direction, a flexible gear whose inner diameter is fitted on the outer surface of the outer ring 3. The assembly thus shaped is arranged in an annulus that has radially inwardly directed teeth and meshes with an opposing flexure gear generally along the diameter. Reference is made to U.S. Pat. No. 4,715,247, U.S. Pat. No. 4,840,090 and U.S. Patent Publication No. 2002/017 88 61, the contents of which are incorporated herein by reference. Can be part.

It is a perspective view of the section of a flexible bearing. It is the perspective view seen from the opposite side of the bearing of FIG. It is a perspective view of the holder | retainer of the bearing of FIG. 1 and FIG. FIG. 4 is a detailed view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6, 7 Annular toroidal raceway 8 Annular part 9 Separating finger 10, 12 Pocket 11 Separating finger 11 11 Different parts 11a Cylindrical surface 13 Claw 14 Projection 15 Recess

Claims (11)

A bearing cage for a harmonic reducer designed to be placed in a bearing to provide a circumferential distance between rolling elements,
A plurality of first pockets comprising means for axially holding the cage on the rolling element;
A plurality of second pockets lacking means for axially holding the cage on the rolling element;
The holding device for a bearing of a harmonic reduction gear, wherein the holding device is integrally formed.   2. A holding device according to claim 1, wherein the means for holding in the axial direction comprises at least one elastic tongue.   The holding device according to claim 2, wherein the elastic tongue portion is integrally formed with the cage.   4. The holding device according to claim 2, wherein the means for holding in the axial direction has two elastic tongues for each pocket.   The holding device according to claim 1, wherein the first pocket and the second pocket are evenly distributed in a circumferential direction.   The holding device according to claim 1, wherein the second pocket has an axial opening provided with a cylindrical end.   The holding device according to claim 1, wherein the first pocket includes a substantially spherical wall portion.   The holding device according to claim 1, wherein the second pocket includes a substantially cylindrical wall portion. Two race rings,
A row of rolling elements disposed between the races;
A bearing for a harmonic reduction gear, comprising: a holding device according to claim 1, which maintains a circumferential distance between the rolling elements.   The bearing according to claim 9, wherein the at least one race is deformable in a radial direction.   A harmonic speed reducer comprising the bearing according to claim 9.

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