GB2212566A

GB2212566A - Bearing assemblies

Info

Publication number: GB2212566A
Application number: GB8826088A
Authority: GB
Inventors: Derrick Gustav Hjertzen
Original assignee: Svenska Kullagerfabriken AB
Current assignee: SKF AB
Priority date: 1987-11-13
Filing date: 1988-11-08
Publication date: 1989-07-26
Anticipated expiration: 2008-11-08
Also published as: IT8822609A0; GB2212566B; DE3838072A1; GB8726583D0; GB8826088D0

Description

22 12560' Bearing Assemblies This invention relates to bearing assemblies

of the kind comprising a housing having a bore fitted with a self-contained rolling bearing unit, the bearing unit comprising an outer bearing ring and an inner bearing ring rotatably mounted in the outer bearing ring by rolling elements disposed between the two bearing rings and arranged to transmit both radial and axial forces between the bearing rings, and the bearing unit having a degree of freedom of movement within the housing in the axial direction or in pivotal directions about a transverse axis.

Bearing assemblies of this kind are suitable for use in applications in which the bearing unit is subjected to axial movement, axial misalignment and/or pivotal oscillating movement, for example in a road vehicle for support of the propeller shaft intermediate its ends. The bearing unit in such applications must be free to move within its housing to prevent excessive load reaction between the rolling elements, cage, and raceways in the bearing rings.

In bearing assemblies of this kind in which the bearing unit is mounted in a cylindrical or part-spherical bore in a metallic housing, clearance is commonly provided between one or both of the bearing rings and the seating on the respective housing or shaft supported in the bearing assembly. Such clearance under certain loading conditions allows the bearing rings to creep or rotate on their seatings and this can cause fretting or serious wear.

1 -2 It is known to provide bearing assemblies of the kind described in which the bearing unit is mounted in a housing made of resilient material such as natural or synthetic rubber, or resilient plastics, or on a resilient seating which can act as a diaphragm to allow movement of the bearing unit and dampen vibration. The bearing unit is usually bonded to the housing or seating material, but this construction has the disadvantage that the bearing unit cannot be separated from the housing or seating and, if one of the components needs to be replaced, the whole assembly must be changed. Also, the bonding of the bearing unit to the housing or seating increases the difficulty of inserting the rolling elements between the bearing rings without damage to the bonded material. Furthermore, although the housing or seating may be designed as a diaphragm, restrictions in the external outer frame can cause high stresses resulting in fatigue of the resilient material.

According to the present invention there is provided a bearing assembly of the kind described, wherein the housing is formed of softer material than the outer bearing ring, and the radially outer surface of the outer bearing ring is formed with axial serrations engaged in corresponding axial grooves formed in the wall of the bore in the housing by the fitting of the bearing unit in the bore of the housing, the arrangement being such that the bearing unit is capable of axial movement, axial misalignment and/or pivotal oscillating movement within the housing in the direction of the serrations while the engagement of the serrations 1 in the grooves prevent creep or rotational movement of the bearing unit within the housing.

In the bearing assembly of the invention, the bore in the housing may be of substantially constant diameter and the outer bearing ring formed with a cylindrical outer surface provided with the above mentioned serrations, the bearing unit being capable of axial movement within the housing. Alternatively, the bore in the housing may be part-spherical and the outer bearing ring formed with a corresponding part spherical outer surface provided with the above-mentioned serrations, the bearing unit being capable of pivotal movement about an axis perpendicular to the axis of the bearing unit so as to be self- aligning.

The serrations must be of sufficient depth and shape to allow freedom of movement of the bearing unit within its housing to accommodate axial movement, oscillatory movement or misalignment while preventing angular radial movement in a rotational direction. The serrations preferably lie along axial planes of the bearing unit and may be formed only on diametrically opposite portions of the outer bearing ring. Also the serrations may extend across the full width of the outer bearing ring, or alternatively the serrations may be formed only on one or both of the end portions of the outer surface of the outer bearing ring.

In a self-aligning bearing assembly according to the invention in which the bore in the housing is part-spherical, the end portions of the outer periphery of the outer bearing ring may be part-spherical and formed with serrations lying in axial planes of the bearing unit, and the centre portion of the outer periphery of the outer bearing ring formed as a substantially cylindrical surface.

Self-contained ball bearing units for use in a bearing assembly according to the invention are illustrated in the accompanying drawings, in which like parts are denoted by like reference numerals 10 and in which:

Figure 1 is a view of a part-spherical bearing unit taken perpendicular to the axis thereof, the upper portion showing the bearing unit in axial cross section and the lower portion showing the outer periphery of the outer bearing ring; Figure 2 is a view of the bearing unit of Figure 1 taken along the axis of the bearing unit; Figure 3 is a view of a housing for the bearing unit of Figure taken along the axis thereof; Figure 4 is a cross section of the housing of Figure 3 taken 20 along the line IV-IV in Figure 3 and showing the bearing unit of Figures 1 and 2 being inserted into the housing; Figure 5 is a view similar to Figure 1 of a cylindrical bearing unit; c n Figure 6 is a view of the bearing unit of Figure 5 taken along the axis of the bearing unit; Figure 7 is a cross section of a housing fitted with the bearing unit of Figures 5 and 6; Figure 8 is a view similar to Figure 1 of a modification of the part-spherical bearing unit of Figure 1, the upper portion showing the bearing unit in axial cross section and the lower portion showing the outer periphery of the outer bearing ring; Figure 9 is a view of the bearing unit of Figure 8 taken along the axis of the bearing unit; Figure 10 is a view similar to Figure 5 of a modification of the cylindrical bearing unit of Figure 5, the upper portion showing the bearing unit in axial cross section and the lower portion showing the outer periphery of the outer bearing ring; Figure 11 is a view of the bearing unit of Figure 10 taken along the axis of the bearing unit; Figure 12 is a view similar to Figure 5 of another modification of the cylindrical bearing unit of Figure 5; and Figure 13 is a view similar to Figure 5 of a further modification of the cylindrical bearing unit of Figure 5.

The bearing unit of Figures 1 and 2 comprises an outer bearing ring 10, an inner bearing ring 11, and a plurality of balls 12 disposed in a cage 13 between the two bearing rings and in rolling engagement with groove raceways 14, 15 in the two bearing rings 10, 11 respectively, so that the bearing unit is self-contained and adapted to transmit radial and axial forces between the two bearing rings. The radial outer surface of the outer bearing ring is part-spherical and formed around its full periphery with axial serrations 16 which extend across the full width of the outer bearing ring.

The housing shown in Figures 3 and 4 has a central part-spherical bore 20 for reception of the bearing unit of Figures 1 and 2. One face 21 of the housing is flat to enable the housing to be secured to a flat support (not shown) by bolts engaged in apertures 22 in the housing. Diametrically opposite portions 23 at one end of the part-spherical bore 20 are cut away to enable a part-spherical bearing to be mounted in the bore in the manner well known in the art by first positioning the bearing unit across the cut away portions 23 with the axis of the bearing unit perpendicular to that of the bore, sliding the bearing unit into the centre of the bore, and then swivelling the bearing unit in the direction of the arrow A shown in Figure 4 to align the axis of the bearing unit with the axis of the bore in the housing.

In accordance with the present invention, the housing is of softer material than that of the outer bearing ring 10 of the bearing unit, and the diameter of the part-spherical bore in the housing is slightly less than the maximum diameter of the outer bearing ring 10 across the crests of the serrations 16 so that, when the bearing unit is swivelled into axial alignment with the housing as shown in Figure 4, the serrations 16 cut axial grooves in the wall of the bore in the c housing. The bearing unit can conveniently be swivelled into axial alignment with the housing by torque exerted by a cylindrical dolly 24 mounted in the inner bearing ring 11 of the bearing unit. The dolly is then replaced by the shaft to be supported by the bearing assembly.

In the operation of the bearing assembly of Figure 4, the shaft is a tight fit or otherwise secured to the inner bearing ring 11, and the shaft together with the bearing unit is capable of a small degree of freedom of movement within the housing in a pivotal direction about a transverse axis, the serrations 16 on opposite sides of the transverse axis sliding along the corresponding grooves in the bore 20 of the housing. The serrations prevent rotational movement of the outer bearing ring relative to the housing.

The bearing unit of Figures 5 and 6 is similar to that of Figures 1 and 2 and comprises an outer bearing ring 30, an inner bearing ring 11, and balls 12 mounted in a cage 13 and in rolling engagement with groove raceways 14, 15 in the two bearing rings 30, 11 respectively. The radial outer surface of the outer bearing ring 30 is however cylindrical and formed around its full periphery with axial serrations 31 which extend across the full width of the outer bearing ring.

The housing shown in Figure 7 is similar to that of Figures 3 and 4, except that its bore 40 is cylindrical. The housing is made of softer material than that of the outer bearing ring 30 of the bearing unit of Figures 5 and 6, and the cylindrical bore 40 of the housing is of a size such that, when the bearing unit is pressed into the bore of the housing, the serrations 31 on the bearing unit cut axial grooves in the wall of the bore 40 in the housing.

Figure 7 shows a shaft 41 supported in the bearing assembly. The shaft is mounted as a tight fit in the inner bearing ring 11 or is otherwise secured to the inner bearing ring. In operation, the shaft and bearing unit are capable of a small degree of axial movement in the bore of the housing with the serrations 31 on the bearing unit sliding along the grooves in the wall of the bore 40 in the housing. The serrations prevent rotational movement of the outer bearing ring 30 relative to the housing.

The bearing unit of Figures 8 and 9 is similar to that of Figures 1 and 2 except that the part-spherical outer surface of the outer bearing ring 44 has axial serrations 45 formed only on diametrically opposite portions of the radial outer surface of the outer bearing ring. When the bearing unit is mounted in a housing as shown in Figure 4, the bearing unit is particularly adapted for pivotal movement about a transverse axis passing symmetrically between the axial serrations 45.

The bearing unit of Figures 10 and 11 is similar to that of Figures 5 and 6 except that the cylindrical outer surface of the outer bearing ring 46 has axial serrations 47 formed only on the end portions of the outer surface of the outer bearing ring. The centre 1 t:

portion 48 of the outer surface of the outer bearing ring provides a smooth cylindrical surface having a diameter equal to the maximum diameter across the crests of the serrations.

The bearing unit of Figure 12 is similar to that of Figure 5, except that the central portion of the radial outer surface of the outer bearing ring 50 has an annular groove 51 and the end portions of the radial outer surface on opposite sides of the groove 51 have axial serrations 52, the diameter of the groove 51 being less than the minimum diameter across the valleys of the serrated end portions of the outer bearing ring.

The bearing unit of Figure 13 is similar to that of Figure 5 except that only one end portion of the cylindrical outer surface of the outer bearing ring 55 is formed with axial serrations 56 and the remainder of the radial outer surface provides a smooth cylindrical surface 57 with a diameter equal to the minimum diameter across the valleys of the serrated end portion.

It is of course to be understood that the arrangement of serrations shown in Figures 10, 12, 13 could be applied to a part-spherical outer surface on the outer bearing ring of a bearing unit, and that such serrations could be applied only to two diametrically opposite portions of the outer bearing ring. Also, the arrangement of serrations shown in Figure 5 could be applied only to diametrically opposite portions of a cylindrical outer surface on the - 10 1 outer bearing ring of a bearing unit. The arrangement of serrations on the bearing unit for any particular application would depend on design criteria including the radial, axial and frictional forces acting on the bearing unit in operation, and ease of manufacture.

Claims

CLAIMS:

1. A bearing assembly comprising a housing having a bore fitted with a self-contained rolling bearing unit, the bearing unit comprising an outer bearing ring and an inner bearing ring rotatably mounted in the outer bearing ring by rolling elements disposed between the two bearing rings and arranged to transmit both radial and axial forces between the bearing rings, and the bearing unit having a degree of freedom of movement within the housing in the axial direction or in pivotal directions about a transverse axis, wherein the housing is formed of softer material than the outer bearing ring, and the radially outer surface of the outer bearing ring is formed with axial serrations engaged in corresponding axial grooves formed in the wall of the bore in the housing by the fitting of the bearing unit in the bore of the housing, the arrangement being such that the bearing unit is capable of axial movement, axial misalignment and/or pivotal oscillating movement within the housing in the direction of the serrations while the engagement of the serrations in the grooves prevent creep or rotational movement of the bearing unit within the housing.

2. A bearing assembly as claimed in claim 1 wherein the bore in the housing is of substantially constant diameter and the outer bearing ring has a cylindrical outer surface provided with the said serrations, the bearing unit being capable of axial movement within the housing.

3. A bearing assembly as claimed in claim 1, wherein the bore in the housing is part-spherical and the outer bearing ring has a corresponding partspherical outer surface provided with the said serrations, the bearing unit being capable of pivotal movement about an axis perpendicular to the axis of the bearing unit so as to be self aligning.

4. A bearing assembly as claimed in any of claims 1-3, wherein the serrations lie along axial planes of the bearing unit.

5. A bearing assembly as claimed in claim 4 wherein the serrations are formed only on diametrically opposite portions of the outer bearing ring.

6. A bearing assembly as claimed in any of the preceeding claims, wherein the serrations extend across the full width of the outer bearing ring.

7. A bearing assembly as claimed in any of claims 1-5 wherein the serrations are formed only on one or both of the end portions of the outer surface of the outer bearing ring.

8. A bearing assembly as claimed in claim 3, wherein the end portions of the outer surface of the outer bearing ring are part-spherical and formed with said serrations, and the centre portion of the outer surface of the outer bearing ring is cylindrical.

9. A bearing assembly as claimed in claim 1 and fitted with a self-contained rolling bearing unit substantially as hereinbefore described with reference to Figures 1 and 2, or Figures 5 and 6, or Figures 8 and 9, or Figures 10 and 11, or Figure 12, or Figure 13 of the accompanying drawings.

Published 1989 atThe Patent Office, State House, 66,71 HighHolborn, London WCIR4TP.Further copies maybe obtainedfrom The PateritOffice. Sales Branch, St Mary Cray, Orpington, Rent BR5 3RD, Printed by Multiplex techniques ltd, St Mary Cray. Kent, Con. V87