GB2381049A

GB2381049A - Roller bearing having independent rentention means

Info

Publication number: GB2381049A
Application number: GB0219171A
Authority: GB
Inventors: Stephen Terence Wilkinson; Charles Roderick Reed
Original assignee: NSK European Technology Co Ltd
Current assignee: NSK European Technology Co Ltd
Priority date: 2001-08-16
Filing date: 2002-08-16
Publication date: 2003-04-23
Anticipated expiration: 2022-08-16
Also published as: GB0120040D0; GB0219171D0; GB2381049B

Abstract

A roller bearing comprises inner and outer rings 5, 3, a series of dumb-bell shaped rolling elements 2 positioned therebetween, independent retention means 4 (in the form of a resilient split ring and which acts so as to retain the rolling elements 2 between the rings 3, 5), and wherein the inner peripheral surfaces of the rings 3, 5 extend with uniform spacing over the whole axial width of the bearing, each rolling element 2 having a groove 20 which extends radially inwards from their outmost surface and the independent retention means 4 being located in the rolling element's groove 6 as well as in groove 20 of the inner peripheral surface of one of the rings. During operation of the bearing relative radial and axial displacements can occur between roller 2 and rings 3, 5 and results in gaps 8, 9 increasing/decreasing in size. Bases 17, 18 and flank walls 10 of grooves 6, 20 limit the displacement of retention member 4. A continuous cage element (7, Fig 5) comprising a series of shaped blocks/wedges (37) between rollers 2 thereby define pockets (37') and joining strips (12) extend between blocks (37). Also disclosed is a cage which is partly deformable so as to assume a smaller/longer diameter than that defined by the fitment of the cage with rolling elements 2, and a method of fitting such a cage in to a bearing arrangement.

Description

ROLLER BEARINGS The present invention relates to roller bearings, particularly, but not solely bearings with cylindrical rollers.

It is well known to construct roller bearings with ribs on the flanks of the bearing rings to retain the rollers between the rings. There is however a need to provide an improved construction wherein the ribs are replaced by other means for imposing axial restraint on the rollers. An object of the invention is to fulfil such a need.

In one aspect the invention provides a roller bearing composed of relatively rotatable inner and outer rings with a series of rollers disposed between the rings and retention means for retaining the rollers axially between the rings; wherein the innermost peripheral surfaces of the rings extend uniformly over the entire axial width of the bearing, the rollers each have a groove extending radially inwardly from their outermost peripheral surfaces and the retention means is a separate independent retention member which locates in the grooves of the rollers and also in a groove on the innermost peripheral surface of one of the rings.

The confronting grooves in the ring and the rollers may be axially central of the bearing. A suitable article usable for such an independent retention member is a split ring or circlip made of resilient material. To aid fitment of the circlip the groove in the bearing ring designed to receive the circlip can be sufficiently deep for the circlip to be pressed entirely into the ring inner surface enabling the rollers and the other ring to be located by axial sliding. When the grooves in the

rollers are aligned with the ring groove accommodating the circlip the latter can spring out into the roller grooves.

A modified special form of split ring can have centring means which may be spring means such as individual leaf springs which rest on the base of the ring groove to locate the body of the ring partly in the ring groove and partly in the roller grooves. The retention means may further comprise a further ring or series of ring-like segments which locates in the grooves of the rollers diametrically opposite to the retention member and within a complementary groove on the innermost peripheral surface of the other bearing ring. Preferably the further ring or each of the segments making up the further ring is spring biased outwardly or inwardly of the reception groove.

Roller bearings in accordance with the invention may also have a cage for maintaining separation of the rollers. One form of cage has shaped blocks fitting between the rollers and strip-like joining pieces connecting the blocks on the inner periphery of the cage. These joining pieces can also engage in the roller grooves but in a diametrically opposed relationship to the retention member. Instead of a continuous cage a number of separate spacers can be fitted between the rollers to maintain their separation as is known but these spacers also have rib-like projections which engage in the grooves of adjacent rollers and act as the aforementioned retention means.

In other embodiments of the invention the function of the cage in maintaining roller separation can be performed by adaptations of the retention means. Thus the single one-piece retention member can be shaped with radial projections which fit between the rollers and maintain their

separation. Curvilinear recesses can lie between these projections and fit partly around the shanks of the rollers defined by the roller grooves. Such a construction has the advantage that it inherently holds the rollers in position so one or both bearing rings can be disassembled without the rollers becoming separated.

To aid fitment, the retention member can be split axially and if the member is flexible enough it can be wound into the ring groove before the rollers and the other ring is introduced. To further aid fitment at least one of the rings of the bearing can be split circumferentially.

In other embodiments the retention means function is taken by a special cage but again without the need for ribs on the bearing rings. In one such construction, the cage has the usual pockets for receiving the rollers and in addition a ring either continuous or made up of ring segments which locate in the confronting grooves of the rollers and one of the bearing rings. Preferably the cage also has axial end walls confronting the outer side faces of the rollers. It is desirable for the pockets in the cage to be shaped to retain the rollers radially inwardly so that when the bearing is dismantled the rollers are held by the cage when the inner ring is removed.

In another aspect the invention provides a bearing with inner and outer rings and rolling elements therebetween and a cage serving to maintain separation between the rolling elements, wherein the cage is at least partly deformable, and preferably resiliently deformable, to assume a diameter smaller or larger than that defined by the fitment of the cage with the rolling elements and such deformation aids such fitment of the cage.

The invention also provides a method of fitting a cage into a bearing with inner and outer rings and rolling elements therebetween, the cage serving to maintain separation between the rolling elements, said method comprising exerting force on the cage to increase or decrease its size or diameter, placing the deformed cage in position and allowing or causing the cage to reassume its undeformed state.

The invention may be understood more readily, and various other aspects and features of the invention may become apparent, from consideration of the following description.

Embodiment of the invention will now be described, by way of examples only, and with reference to the accompanying drawings, wherein: Figure 1 is a schematic cross-sectional view of part of a roller bearing of known construction; Figure 2 is a schematic cross-sectional view of part of a roller bearing constructed in accordance with the invention; Figure 3 is a view on an enlarged scale showing the relative position of the retention member used in the construction shown in Figure 2; Figure 4 is a sectional side view taken along the line IV-IV of Figure 3 and showing a modified construction for the retention member;

Figure 5 is a schematic cross-sectional view of part of a modified form of a roller bearing in accordance with the invention; Figure 6 is a diagrammatic perspective view of the construction represented in Figure 5; Figure 7 is a schematic cross-sectional view of part of another roller bearing constructed in accordance with the invention; Figure 8 is a diagrammatic representation of one of a series of spacers used in a further roller bearing constructed in accordance with the invention; Figure 9 is a schematic cross-sectional view of part of another roller bearing constructed in accordance with the invention; Figure 10 is a sectional side view taken along the line X-X of Figure 9; Figure 11 is a schematic cross-sectional view of part of a further roller bearing constructed in accordance with the invention; Figure 12 is a diagrammatic perspective representation of part of the retention member used in the construction depicted in Figure 11 ;

Figure 13 is a diagrammatic perspective representation of the fitment of the retention member shown in Figure 12 ; Figure 14 is a schematic cross-sectional view of part of a further roller bearing constructed in accordance with the invention; Figure 15 is a schematic representation of part of the cage used in the bearings shown in Figures 13 and 14 showing a modification; Figures 16 and 17 are diagrammatic part sectional side views of part of another cage showing the deformation thereof ; Figure 18 is a schematic cross-sectional view of part of the further roller bearing constructed in accordance with the invention; Figure 19 is a schematic cross-sectional view of part of another roller bearing constructed in accordance with the invention; Figure 20 is a diagrammatic cross-sectional view of a modified form of the roller bearing shown in Figures 2 and 3; Figure 21 is a sectional view of a roller bearing with an adjustable cage constructed in accordance with the invention;

Figures 22 and 23 are diagrammatic part-sectional side views of the cage shown in Figure 21 in expanded and contracted states and Figure 24 is a diagrammatic part-sectional plan view of another roller bearing equipped with a cage constructed in accordance with the invention.

Figure 1 depicts a known type of roller bearing composed of an outer ring 3, an inner ring 5 and a series of cylindrical rollers 2 therebetween. A cage 7 serves to maintain separation between the rollers 2. The rollers 2 are retained axially by means of radially inwardly extending ribs 23 on the outer side regions of the outer ring 3 and by a radially outwardly extending rib 23 on one of the outer side regions of the inner ring 5. The axial dimension'''1''or thickness of the ribs 23 limits the axial dimension of the rollers 2.

Figures 2 and 3 depict a roller bearing assembly constructed in accordance with the invention where the ribs 23 are omitted so that the axial dimension of the rollers 2 is increased. Indeed, the axial dimension of the rollers 2 is only slightly smaller than the width of the rings 3,5. In this construction, the rollers 2 are retained axially solely by means of an independent floating retention member 4 here composed of a ring-like resilient circlip made of spring steel. The member 4 engages in a groove 20 in the inner surface of the outer ring 3. Each of the rollers 2 has a central groove 6 which is aligned with the groove 20 and also receives the retention member 4. The rollers 2 have a dumbbell shape.

Figure 3 shows the normal idealised disposition of the member 4 with radial gaps 8 between the bases 17,18 of the grooves 20,6 and the member 4 and axial gaps 9 between the flank walls 10 of the grooves 6,20 and the member 4. During operation of the bearing relative radial and axial displacements can occur between each roller 2 and the rings 3,5 which results in the gaps 8,9 increasing and decreasing in size and the bases 17,18 and the flank walls 10 of the grooves 20,6 limit the axial and radial displacements of the retention member 4. During assembly, the member 4 can be inserted into the groove 20 prior to fitting the rollers 2 and the inner ring 5. If the groove 20 is deep enough the retention member 4 can be compressed against its spring force within the groove 20 and the rollers 2 and the inner ring 5 can be fitted by sliding axially into place so that the retention member 4 springs out into the grooves 6 of the rollers when the grooves 6,20 are aligned.

Figure 4, however, depicts a modified arrangement where a series of centring elements in the form of individual leaf spring elements 19 are provided on the outer periphery of the member 4 to rest on the base 17 of the groove 20 and thereby hold the main body of the retention member 4 in the floating location. The bowed shape for the spring elements 19 permits the member 4 to be compressed within the groove 20 as discussed above.

In the constructions represented in Figures 2 to 4, the cage 7 is omitted but it is quite feasible to fit a cage 7 unless a full complement of rollers is used without a cage at all. However, modified forms of cages can be used in bearings in accordance with the invention. Thus Figures 5 and 6 depict a construction where the retention member 4 is supplemented by a continuous cage 7 which has a series of shaped blocks or wedges 37 which locate between the rollers 2 to define

pockets 37'receiving the rollers 2 and narrow joining strips 12 extending between the blocks 37. The joining strips 12 serve to fit within the grooves 6 in the rollers 2 diametrically opposite to the retention member 4. In Figure 6 the rollers 2 are shown in chain-dotted outline.

In Figure 7 the retention member 4 is supplemented by individual spacers 13 each of which lie between an adjacent pair of the rollers 2 and serve solely to maintain roller separation.

Figure 8 depicts another embodiment where there are again individual spacers 13'supplementary to the retention member 4 but these spacers 13'each have ribs 4'extending in opposite directions and engaging in the grooves 6 to act as the retention means 4 for a pair of the rollers 2 (only one of which is shown). The spacers 13'have end portions 47 which have curved faces 48 confronting the outer peripheral surfaces of the associated rollers 2.

Figures 9 and 10 depict a further roller bearing constructed in accordance with the invention which again has no ribs 23 on the outer and inner rings 3,5. In this case the retention member 4 is prolonged radially inwardly to possess projections 15 fitting between adjacent rollers 2. As shown, the projections 15 have curvilinear cut-outs 11 between the projections 15 which fit around the shanks 24 of the rollers 2 defined by the presence of the grooves 6. In this way the projections 15 also act as a cage with pockets receiving the rollers 2 to maintain the separation of the rollers. It can be seen in Figure 10 that the regions of the member 4 which fit in the grooves 6 provide a more substantial material contact area with respect to the flank walls 10 of the grooves 6. This construction does present assembly difficulties with regard to the retention member 4 even when the rollers and inner ring are not present. To assist it is desirable to split the outer ring

3 into two axially separable portions 3', 3"as shown in Figure 11. The retention member 4 with the features shown in Figures 9 and 10 is also split radially anct now has a stepped profile 14 enabling the ends of the retention member 4 to be separated or brought together. The stepped profile 14 can be made rigid by using an appropriate fastener which can be removable if desired.

This type of separation enables the member 4 to have one end flexing radially inwards and sideways to enable a spiralling action in order to feed in the retention member 4 into the groove 20 as shown in Figure 13.

In the modified construction shown in Figure 14 the retention member 4 is formed from block like regions 27 of the cage 7 engaging in the confronting grooves 20,6 as in the previous embodiments.

In the embodiments represented in Figures 9 to 14 the inner bore 28 of the cage may be so constructed as to retain the rollers 2 when the inner ring 5 is removed during assembly or disassembly. This is illustrated in Figure 14 where the inner bore 28 of the cage 7 is located at a distance 29 offset from the axes 30 of the rollers 2. The material of the cage pockets partly surrounding the rollers 2 can hold the rollers 2 in position in the radially inward direction. To facilitate the assembly of the cage 7 with the retention feature shown in Figure 14 the outer ring 3 can be split as shown in Figure 11 as 3', 3". Figure 15 however depicts another arrangement which in a similar manner to Figure 12 has a separation gap 33 in the cage itself. In a similar manner to Figure 12, provided the cage 7 is sufficiently flexible, it may have one end spiralled into the groove 20 as generally represented in Figure 13.

In Figures 16 and 17 the cage 7 has deformable and preferably resiliently deformable elements 31 which enable the cage 7 to be collapsed radially inwards as represented in these illustrations. The deformable or foldable elements 31 allow the diameter of the cage 7 to be reduced temporarily (see reference 32 in Figure 17) thus facilitating the fitting of the cage 7 as the cage 7 expands again.

The deformable regions or elements 31 can also act in the reverse sense to Figures 16 and 17 so that the cage is not reduced in size. In this alternative arrangement the elements 31 or the entire cage 7 would be subjected to tensile force to stretch the cage 7 into the increase size. The compressible cage 7 of Figures 16 and 17 enables the cage 7 to expand into the outer ring while the alternative expandable cage 7 enables the cage to contact into the inner ring.

The provision of the deformable elements 31 is facilitated by the grooves 6 in the rollers 2 which can accommodate these elements 31. The elements 31 can be located at the inner region of the shank 24 rather than the outer region as shown in Figures 16 and 17.

Figure 18 shows an alternative construction for the roller bearing with grooved rollers and the retention means where a ring 34 forms an interference fit in the groove 20 in the outer ring 3 and this ring 34 constitutes the retention member 4 which fits in the grooves 6 in the rollers 2.

In the construction shown in Figure 19, each of the rings 3,5 has a groove 20 on the inner face and the independent retention member 4 engages in the grooves 6 of the rollers 2 and the groove

20 of the ring 3 as before is supplemented by a spring loaded ring 29 or a series of ring segments 29 engaging in the groove 20 in the inner ring 5.

Figure 20 shows a bearing with a construction of the type shown in Figures 2 to 4. In this modification the inner ring 5 has a series of lubrication bores 36 passing through the ring 5 which allow lubricant to be introduced into the centre of the bearing. One advantage of this arrangement which makes use of the grooves 6 for the collection of lubricant is that the lubricant can flow into the centre of the bearing and does not suffer from blockage as the rollers 2 pass over the lubrication outlets.

The concept of a cage which can be subjected to force or deformed to assume a different diameter or size that when it is fitted can be applied to other types of bearings with balls as rolling element or non-cylindrical or cylindrical rollers without grooves. In the latter case the means for accommodating the size adjustment would have to be positioned in other ways to that shown in Figures 16 and 17.

Figures 21 to 24 illustrate other examples of adjustable cages. In Figure 21 the inner ring 5 of a roller bearing has side ribs 40 which obstruct the fitment of a normal non-adjustable cage. Figures 22 and 23 show the deformable elements 31 adjoining the pocket defining regions of the cage 7 in which the rollers 2 are located. In this case the elements 31 lie between the rollers 2 and the pockets and inter-engaging slidable guide fingers 42 serve to guide the expansion and contraction of the cage 7 as depicted in Figures 22 and 23.

Instead of being disposed in radially offset locations the fingers 42 and the elements 31 can be disposed in axially offset locations. This is represented in Figure 24 which is a plan view ol a roller bearing used as a thrust bearing. The reference numerals 31 and 42 again denote the deformable elements and the guide fingers.

Figures 16,17 and 21 to 24 exemplify a cage constructed in accordance with the invention usable with bearings of various types. Such a cage is characterised by means permitting its adjustment between one state where it is adapted to receive rolling elements of a bearing in pockets and another state which differs dimensionally from the one state. Although such adjustment is useful as an aid to fitment the ability of the cage to change dimensions can be useful in other applications where the shape of the cage can change dynamically. Such a change can be induced, for example, by a change in the loading of the bearing and/or the rolling elements, a change in rotary speed and/or on misalignment of the bearing rings.

Claims

CLAIMS 1. A roller bearing composed of relatively rotatable inner and outer rings with a series of rollers disposed between the rings and retention means for retaining the rollers axially between the rings; wherein the innermost peripheral surfaces of the rings extend with uniform spacing over the entire axial width of the bearing, the rollers each have a groove extending radially inwardly from their outermost peripheral surfaces and the retention means is a separate independent retention member which locates in the grooves of the rollers and also in a groove on the innermost peripheral surface of one of the rings.
2. A roller bearing according to claim 1, wherein axial dimension of the rollers is slightly smaller than the axial dimension of the rings.
3. A roller bearing according to claim 1 or 2, wherein the retention member is a resilient split ring.
4. A roller bearing according to claim 1,2 or 3, wherein the retention member has centring elements which engage on a base of the groove in the bearing ring.
5. A roller bearing according to claim 4, wherein the centring elements are spring elements.
6. A roller bearing according to any one of claims I to 5 and further comprising a cage for maintaining separation of the rollers, wherein the cage is composed of shaped blocks each located

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between a pair of the rollers and defining pockets for receiving the rollers and the blocks are connected by joining strips each of which also engages in the grooves of the rollers in a location diametrically opposite the retention means or retention member.
7. A roller bearing according to any one of claims 1 to 5 and further comprising a plurality of separate spacers fitted between the rollers to maintain separation of the rollers, wherein each spacer has projections which engage in the grooves of adjacent rollers.
8. A roller bearing according to claim 1 or 2, wherein the retention member has radial projections which locate between the rollers and maintain separation of the rollers and curvilinear recesses disposed between the radial projections, each recess partly surrounding a shank of an associated roller defined by the groove therein.
9. A roller bearing according to claim 8, wherein the retention member is split axially.
10. A roller bearing according to any one of the preceding claims, wherein at least one of the rings is split circumferentially.
11. A roller bearing according to claim 1 or 2, wherein the retention means is formed by a ring or ring segments of a cage, the ring or ring-like segments locate in the groove of the rollers and in a groove on the innermost peripheral surface of one of the rings and the cage defines pockets for receiving the rollers and maintains separation of the rollers.

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12. A roller bearing according to claim 11, wherein the cage has axial end walls confronting outer side faces of the rollers.
13. A roller bearing according to claim 10 or 11, wherein the pockets are shaped radially inwardly to retain the rollers in the pockets when the inner ring is removed.
14. A roller bearing according to claim 1 or 2, wherein the retention means also comprises a further ring or series of ring-like segments which locates in the grooves of the rollers diametrically opposite to the retention member and within a groove on the innermost peripheral surface of the other bearing ring.
15. A roller bearing according to any one of claims 6, 11, 12 or 13, wherein the cage has deformable regions which enable the cage dimensions to be changed to aid fitment of the cage.
16. A roller bearing according to claim 15, wherein the deformable regions permit the cage to be compressed to assume a smaller diameter than the diameter when fitted.
17. A roller bearing according to claim 15, wherein the deformable regions permit the cage to be expanded to assume a larger diameter than the diameter when fitted.
18. A roller bearing according to claim 14 and further comprising spring means which biases the further ring or ring-like segments radially outwardly from the base of the groove in the other bearing ring.

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19. A roller bearing according to any one of the preceding claims, wherein the inner ring has a plurality of radial through bores for allowing lubricant to be introduced into the interior of the bearing.
20. A bearing with inner and outer rings and rolling elements therebetween and a cage serving to maintain separation between the rolling elements, wherein the cage is at least partly deformable to assume a diameter smaller or larger than that defined by the fitment of the cage with the rolling elements and such deformation aids such fitment of the cage.
21. A bearing according to claim 20, wherein the cage has resiliently deformable regions which allow the cage to be compressed to assume a smaller diameter than that when it is fitted.
22. A bearing according to claim 20, wherein the cage has resiliently deformable regions which allow the cage to be expanded to assume a larger diameter than that when it is fitted.
23. A cage for a bearing substantially as described with reference to, and as illustrated in, any one or more of Figures 16,17, 21,22, 23 and 24 of the accompanying drawings.
24. A roller bearing according to claim I or 2, wherein the retention member is a ring fixed in a groove in the innermost ring surface.

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25. A roller bearing substantially as described with reference to, and as illustrated in any one or more of Figures 2 to 24 of the accompanying drawings.
26. A method of fitting a cage into a bearing with inner and outer rings and rolling elements therebetween, the cage serving to maintain separation between the rolling elements, said method comprising exerting force on the cage to increase or decrease its size or diameter, placing the deformed cage in position and allowing or causing the cage to reassume its undeformed state.