GB2167815A - A bearing assembly - Google Patents

Abstract

A bearing assembly comprises a bearing 10 having an axis of rotation and axially spaced recesses 19 in the radially outer circumferential surface, which recesses extend circumferentially. Two radially resiliently expansible locating elements 24 are adapted to be removably engaged in the axially spaced recesses to enable a support ring 21, surrounding the bearing, to be axially located therebetween. So that a support ring 21 can be mounted on the bearing 10 and have one of a plurality of axial lengths without having to modify the bearing 10 or locating elements 24, the bearing 10 has three or more recesses 19 in the circumferential surface and each locating element 24 can be removably engaged in any one recess 19. <IMAGE>

Description

SPECIFICATION A bearing assembly This invention concerns a bearing assembly comprising a bearing and two locating elements for locating a ring on the circumferential surface of the bearing.

Patent Specification US 3599200 (Thomson) discloses an assembly comprising a housing, a support ring disposed in a bore of the housing and a linear recirculating ball bearing extending in the bore of and cupported by the support ring. The radially outer circumferential surface of the bearing has two axially spaced recesses or grooves. Two radially resiliently expansibie locating elements or flexible tubular members have radially inwardly extending projections lips or ribs. The locating elements or tubular member are mounted one from each end of the bearing so that the ends of the elements abut the support ring and the projections engage in the respective recesses. The other end of each locating element or tubular member has in-turned lips which hold a sealing ring in place at the end of the bearing.

If an assembly is to be produced with a support ring having a different axial length, then a bearing must be produced having the recesses spaced a different distance apart and either locating elements having a different axial length must be produced or a different length of bearing must be produced to use the same length locating elements. This can be uneconomic considering the possible range for the axial length of the support ring.

The subject of the invention is an assembly which can prove more economical.

The invention provides a bearing assembly comprising a bearing having an axis of rotation and axially spaced recesses in the radially outer circumferential surface, which recesses extend circumferentially, and two radially resiliently expansible locating elements adapted to be removably engaged in the axially spaced recesses to enable a support ring surrounding the bearing to be axially located therebetween, wherein the bearing has three or more recesses in the circumferential surface, each locating element can be removably engaged in any one recess and the ring has one of at least three axial lengths corresponding to the axial distances between the recesses.

The radially resiliently expansible locating elements are preferably rings or split rings which are radially expanded, pushed over the bearing and allowed to snap into the respective recess. A support ring mounted on the bearing and held in position by the locating elements can be readily replaced by one of a different axial length by removing one or both of the locating elements to a different recess.

Also the same support ring can, by the same method, be located in a different axial position along the bearing.

One or each locating element may have two axially spaced abutment surfaces and one or more radially inwardly extending projections for engaging in the respective recess, the or each projection being either symmetrically positioned axially between the abutment surfaces or offset axially towards one abutment surface. ring may have one continuous annular projection and the bearing may have corresponding annular recesses. Each locating element may possibly have one arcuate projection or may have a plurality of projections.

The continuous annular projection and annular recess has the advantage that the locating element does not require orientating before being pushed on the bearing. Similarly, with the or each projection being symmetrically positioned between the abutment faces, no orientation of the locating element-that is, determining which abutment face should contact the support ring-is required. However, with the or each projection being offset towards one abutment face, the range of axial lengths of the support ring that can be mounted is increased. By turning one or both locating elements around the axial distance between their facing abutment surfaces is changed.The axial spacing between the recesses can be regarded as accommodating gross changes in axial length, and the changes effected by turning the locating elements around can be regarded as fine adjustment for accommodating small changes in axial length of the support ring.

Preferably the recesses are arranged symmetrically with respect to a plane extending perpendicular to the bearing axis, there being an even number of recesses, and the recesses are not evenly spaced from one another.

With a symmetrical arrangement of recesses, the support ring can, with a degree of certainty, be mounted symmetrical as regards the bearing. Where the population density of support rings is greater for the smaller lengths than for the greater lengths, then there is an advantage in having the recesses closer towards one another towards the middle of the bearing.

The bearing may be a linear recirculating rolling bearing with a cage and axially extending bars forming the outer circumferential surface of the bearing and the recesses may be provided only by the cage.

The invention also provides, in combination, a bearing assembly according to the invention and a support ring which surrounds the bearing and is located between the two locating elements.

A second bearing may surround the first bearing and be located between the two locating elements, the second bearing providing the support ring.

Preferably, the first bearing is a linear recirculating rolling bearing and the second bearing is a radial rolling bearing thus allowing the assembly both linear and rotational movement.

The second bearing need not be a rolling bearing but may be a plain bearing, for example, a spherical plain bearing.

Embodiments of the invention will now be described by way of example and with refer ence to the accompanying drawings, of which: Figure 1 is a view on arrow I of an as sembly shown partly in Figure 2 comprising a linear recirculating ball bearing extending within the bore of a needle roller bearing, with parts shown in section; Figure 2 is a part of a view of the assembly shown in Figure 1 on ll-ll; Figure 3 is a view along its axis of one of the annular locating elements; Figure 4 is a section of the locating element shown in Figure 5 on IV-IV; Figure 5 is a much enlarged part of a longi tudinal section with the same linear bearing and locating elements as Figures 1 to 4 but with a different rolling bearing deep groove ball bearing; and Figure 6 is a view similar to that of Figure 5 with the same linear bearing and locating ele ments but with a self-aligning ball bearing in stead of the deep groove ball bearing.

Figures 1 and 2 show a linear recirculating ball bearing 10 comprising a plastics cage 11 in the form of a sleeve and a plurality of long itudinally extending metal bars 12 disposed in longitudinally extending recesses 13 in the outer surface of the cage. Each recess 13 has a longitudinal slot 14 opening into the bore of the cage 11. Each recess 13 and respective metal bar 12 defines an endless path in which are accommodated a plurality of balls 15 for recirculation. Each path comprises a first longi tudinal portion 16 in which the balls 15, in use of the bearing 10, transmit loads radially between the bar 12 and a shaft (shown in chain-dot) extending through the bore of the cage 11, and a second longitudinal portion 17 in which the balls 15, in use of the bearing 10, do not transmit such loads.The two long itudinal portions 16 and 17 are interconnected at each end by semi-circular reversal portions 18.

The cage 11 has a plurality of axially spaced recesses 19 adjacent longitudinal recesses 13.

Each recess 19 is in the form of a truncated pyramid having a rectangular base, the base being at the radially outer surface of the cage 11. The recesses 19 are arranged symmetri cally with respect to a plane extending per pendicular to the longitudinal axis of the bear ing 10 and bisecting the bearing. However, on each side of the bisecting plane, the recesses 19 are not evenly spaced from one another and are also of different sizes longitudinal ly-the circumferential width and radial depth being the same.

The cage 11 can be made by injection moulding with the recess 13 and 19 being formed by radial sliders of the mould in a known manner.

The linear recirculating ball bearing 10 is surrounded by a needle roller bearing 20 which comprises an inner ring 21, an outer ring 22 with integral end flanges and a single row of needle rollers 23. The outer ring 22 is located in a housing (not shown). In use, ra dial loads are transmitted between the shaft and housing via the balls 15, bars 12, inner ring 21, needle rollers 23 and outer ring 22.

The inner ring 21 acts as a support ring.

The two bearings 10 and 20 are held in position axially with respect to each other by two radially resiliently expansible annular locat ing elements or snap rings 24, each engaging removably in a respective recess 19 and abutting the flat annular end faces of the inner ring 21.

Referring to Figures 3 and 4, each ring 24 comprises a closed annular radially resiliently expansible portion 25 having a cylindrical bore 26 and two flat annular abutment faces 27 and 28 facing away from each other. The ring 24 also has a plurality of radially inwardly extending projections 29 each also in the form of a truncated pyramid having a rectangular base, the base lying on the cylindrical bore 26. As can be seen from Figure 4, the projections 29 are not arranged symmetrically with respect to the abutment faces 27 and 28, that is, not mid-way between the end faces, but are in fact offset axially towards the end face 28.

When the bearing 20 is to be mounted on bearing 10, the appropriate abutment face 27 or 28 of the two locating rings 24 are selected with respect to the axial position of the bearing 20 and the recesses 19 to be engaged. In Figure 1, the locating rings 24 abut the end faces of the inner ring 21 with their annular faces 27. To assemble the two bearings 10 and 20 then, the bearing 20 is pushed axially onto the outer circumferential surface of bearing 10 and positioned centrally.

Then the two locating rings 24 are orientated the correct way, expanded radially, pushed onto the bearing 10 and allowed to snap into their respective recesses 19.

Bearing 10 also has two annular grooves 30, one at each end and extending in the metal bars 12 as well as the cage 11. One of the locating rings 24 or a known retaining ring (not shown) can be mounted to engage in the annular groove 30 to axially secure an annular member on the bearing 10. This annular member can be, for example, a known sealing washer for sealing the ends of the bearing chamber of the bearing 20.

In one form the linear recirculating ball bearing 10 has six evenly circumferentially spaced recesses 19 with six corresponding projections 29 on each locating ring 24. However, in the illustrated bearing 10, one set of longitudinally spaced recesses 19 has been replaced by a metal bar 12 to increase the load carrying capacity of the bearing. Consequently, each locating ring 24 has only five projections 29.

Figure 5 is a scrap sectional view to an enlarged scale with the same linear recircualting ball bearing 10 with longitudinally spaced recesses 19 and the same radially resiliently expansible locating rings 24. However, the needle roller bearing 20 of Figures 1 and 2 has been replaced by a deep groove ball bearing 31 which comprises a radially inner ring 32 acting as a support ring, a radially outer ring 33 and a single row of balls 34. As can be seen, the ball bearing 31 is not positioned centrally of the linear bearing 10 despite the projections 29 of the locating rings 24 engaging in corresponding recesses 19. This is because the upper locating ring 24, when looking at the drawing of Figure 5 abuts the inner ring 32 of the bearing 31 with its face 27, whereas the lower locating ring 24 abuts the inner ring 32 with its face 28.Since the projections 29 of each locating ring 24 are closer axially to the abutment face 28, the ball bearing 31 is positioned off-centre in the direction towards the lower locating ring 24.

To assemble the construction shown in Figure 5 starting with the construction shown in Figures 1 and 2, one could first of all expand the lower locating ring 24, when looking at the drawing of Figure 1, and remove it axially from the linear bearing 10. Then the needle roller bearing 20 would be pushed off the linear bearing 10 axially (downwardly in the drawing). The other (upper) locating ring 24 would then be expanded and re-positioned in the appropriate recess 19. Then the ball bearing 31 would be pushed onto the outer circumferential surface of the linear bearing 10 until it abutted the face 27 of the (upper) locating ring 24.The first (lower) locating ring 24 would have to be turned around so that its abutment face 28 faces the ball bearing 31 (instead of the abutment face 27), then it would be radially expanded and pushed axially along over the outer circumferential surface of the linear bearing 10 and allowed to contract into the appropriate recess 19.

By removing both the (upper and lower) locating rings 24, turning them around and repositioning them, the ball bearing 31 would be positioned off-centre upwardly, looking at the drawing of Figure 5, with the face 28 of the (upper) locating ring 24 and the face 27 of the (lower) locating ring 24 abutting the annular end faces of the inner ring 32.

Figure 6 is also a scrap view showing the same linear ball bearing 10 with the recesses 19 and the same radially resiliently expansible locating rings 24 engaging in their respective recesses 19. The bearing surrounding the linear being 10 in this embodiment is a selfaligning ball bearing 35 comprising an inner ring 36 acting as a support ring, an outer ring 37 providing a sphered raceway, and two rows of balls 38. The outer ring 37 is secured in the bore of a housing (not shown). As can be seen, the ball bearing 35 is positioned centrally of the linear bearing 10 with the projections 29 of the locating rings 24 engaging in corresponding recess 19. The annular end faces of the inner ring 36 of the ball bearing 35 abut the abutment faces 28 of the locating rings 24.

To assemble this construction starting with that shown in Figure 5, one could first of all radially expand and removed axially upwardly the upper locating ring 24 from the linear ball bearing 10, when looking at the drawing of Figure 5. Then the deep groove ball bearing 31 can be axially pushed off (upwardly) the linear bearing 10. The other (lower) locating ring 24 can then be expanded to disengage it from the recess 19 and then be re-positioned in another, appropriate recess 19. The selfaligning ball bearing 35 can then be pushed onto the outer circumferential surface of the linear bearing 10 until it abuts the face 28 of the other (lower) locating ring 24. Then the first (upper) locating ring 24 is orientated so that its abutment face 28 (instead of abutment face 27) is facing the ball bearing 35.The first (upper) locating ring is then expanded, pushed onto the outer circumferential surface of the linear bearing 10 and allowed to contract into the appropriate recess 19.

The above illustrated and described embodiments show how versatile these constructions are in being able to accommodate various lengths of support or bearing inner ring. Simply re-orientating one or both of the locating rings varies the distance between their facing abutment faces and this, coupled with the fact that the locating rings can be re-positioned in other recesses, means that a large and varied range of axial lengths of the bearing inner or support ring can be positioned and located axially.

In the illustrated and described embodiments, a shaft extending through the linear bearing 10 can have linear and rotational movement. However the rolling bearing 20, 31, 35 can be replaced by a ring having a spherically curved convex outer surface. This ring can then be seated a housing having a corresponding spherically curved concave surface so that a shaft extending through and supporting (or being supported by) the linear bearing 10 can move linearly and angularly relative to the housing. The linear bearing 10 can also be replaced by a radial rolling or plain bearing so allowing a variety of rotary and angular movements.

The illustrated and described embodiments also show that, for each position of the locating or snap rings 24, the linear bearing 10 has a plurality of circumferentially spaced recess as 19. In an alternative embodiment longitudinally spaced annular grooves or recesses may be used similar to the groove 30 in Figure 1 extending into the metal bars 12 as well as the cage 11. This means that the locating rings 24 do not have to be orientated rotationally before being mounted. The locating rings 24 may be split rings made from a hard spring steel with a high load capacity.

The projections 29 of the locating rings 24 are shown as being offset axially. However they can be positioned so that the ring 24 is symmetrical about a plane extending perpendicular to its axis of rotation. This simplifies somewhat the mounting procedure but does reduce the range of axial lengths of supporting ring which can be mounted.

Finally, the outer circumferential surface of the inner bearing and the bore of the support or bearing inner ring can be non-circular in cross-section, for example, elliptical or polygonal, so preventing relative rotation between the inner bearing and support ring.

Claims (12)

1. A bearing assembly comprising a bearing having an axis of rotation and axially spaced recesses in the radially outer circumferential surface, which recesses extend circumferentially, and two radially resiliently expansible locating elements adapted to be removably engaged in the axially spaced recesses to enable a support ring surrounding the bearing to be axially located therebetween, wherein the bearing has three or more recesses in the circumferential surface, each locating element can be removably engaged in any one recess and the ring has one of at least three axial lengths corresponding to the axial distances between the recesses.

2. A bearing assembly as claimed in Claim 1, wherein one or each locating element has two axially spaced abutment surfaces and has one or more radially inwardly extending projections for engaging in the respective recess, the or each projection being offset axially towards one abutment surface.

3. A bearing assembly as claimed in Claim 1 or 2, wherein the recesses are arranged symmetrically with respect to a plane extending perpendicular to the bearing axis, there being an even number of recesses.

4. A bearing assembly as claimed in Claim 1, 2 or 3, wherein the recesses are not evenly spaced from one another.

5. A bearing assembly as claimed in any preceding claim, wherein the bearing is a linear recirculating rolling bearing with a cage and axially extending bars forming the outer circumferential surface of the bearing.

6. A bearing assembly as claimed in Claim 5, wherein the recesses are provided only by the cage.

7. A bearing assembly comprising a bearing and two locating elements substantially as herein described with reference to and as shown in the accompanying drawings.

8. In combination, a bearing assembly as claimed in any preceding claim and a support ring which surrounds the bearing and is located between the two locating elements.

9. In combination, a bearing assembly as claimed in any one of Claims 1 to 7 and a second bearing which surrounds the first bearing and is located between the two locating elements, the second bearing providing the support ring.

10. A combination as claimed in Claim 9 when dependant on Claim 5 or 6, wherein the second bearing is a radial rolling bearing.

11. In combination, a bearing assembly comprising a bearing and two locating elements, and a ring surrounding the bearing and located by the locating elements substantially as herein described with reference to and as shown in the accompanying drawings.

12. In combination, a bearing assembly comprising a bearing surrounding the first bearing and located by the locating elements substantially as herein described with reference to and as shown in the accompanying drawings.