GB2373549A

GB2373549A - Rolling element bearing seals

Info

Publication number: GB2373549A
Application number: GB0200514A
Authority: GB
Inventors: Simon Peter Pitt; Jill Marie Barker
Original assignee: NSK European Technology Co Ltd
Current assignee: NSK European Technology Co Ltd
Priority date: 2001-01-12
Filing date: 2002-01-10
Publication date: 2002-09-25
Anticipated expiration: 2022-01-10
Also published as: GB0200514D0; GB2373549B; GB0100916D0

Abstract

A rolling element bearing 10 has inner and outer rings 11, 12 with rolling elements 9 spaced apart with a cage 8 therebetween. Seals 15 extend between the rings 11, 12 to act as barriers screening off the interior of the bearing 10 from the surroundings. At least one of the seals 15 is equipped with a holding member 19 press-fitted into a groove 20 in the stationary ring 11, at least one filter body 18 and sealing means 21 at least partly engaging in a groove 22 in the rotatable ring 12. The sealing means 21 has sealing lips 23, 24 extending in different directions one of which is engaged in rubbing contact with a flank wall 26 of the associated groove 22. The filter body 18 is porous to lubricant and permits lubricant to pass to and from the bearing interior while restricting the passage of contaminants.

Description

ROLLING ELEMENT BEARING SEALS The present invention relates to rolling element bearings and more particularly to seals therefor.

It is known with bearings used in certain environments, particularly with bearings used in gear boxes, to run the bearings completely open, i. e. without seals, and to allow a flowable lubricant or oil to pass through the bearings. Particles from inside and outside the gear box can however enter the bearing and cause damage. Another approach is to provide a completely sealed bearing. In this case the seals act as barriers to prevent the ingress of contaminants and to retain a more viscous lubricant or grease within the bearing interior. In other applications, such as a continuously variable transmission unit it is vital to prevent contaminants from entering the transmission fluid and any contaminants created inside a bearing of such a unit should be trapped within the bearing itself.

An object of the invention is to provide an improved bearing seal which reliably prevents the passage of contaminants but allows lubricant to flow therethrough.

According to the invention there is provided a rolling element bearing composed of relatively rotatable inner and outer rings with rolling elements therebetween and at least one seal which establishes a barrier between the rings, wherein the seal is of composite form with at least one filter body or region permitting the passage of lubricant through the barrier while inhibiting the passage of contaminants through the barrier and with sealing means which is at least partly received in a groove in the rotatable ring; the sealing means having separate sealing lips extending in different axial directions.

The bearing can be fitted with two of the aforementioned seals or with one seal as aforementioned and another seal acting as a barrier for contaminants and lubricant. In the former case flowable lubricant can be circulated through the bearing interior passing inwardly through one seal and outwardly through the other seal.

In another aspect, the invention provides a composite seal for use in a bearing constructed in accordance with the invention and composed of at least one filter body made from a porous material for permitting the passage of lubricant while trapping contaminant particles, a holding member at one radial end region of the seal which serves to retain the seal in place by fitment into a groove in one of the bearing rings and a sealing member at the other opposite radial end region of the seal which is receivable at least partly in a groove in the other of the bearing rings and establishes sealing relationship with the other of the bearing rings with the aid of separate sealing lips extending in different axial directions.

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

Embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings in which: Figure 1 is a schematic cross-section of part of a rolling element bearing incorporating a seal constructed in accordance with the invention; Figure 2 is a schematic cross-section of part of a rolling element bearing incorporating another seal constructed in accordance with the invention and Figure 3 is a schematic cross-section of part of a rolling element bearing incorporating a further seal constructed in accordance with the invention.

As shown in Figure 1, a rolling element bearing 10 is composed of an outer ring 11 and an inner ring 12 with rolling elements (not shown) making rolling contact with tracks on the confronting surfaces 13,14 of the inner and outer rings 11,12. A composite seal 15 forms a barrier 16 extending between the rings 11,12 adjacent the outer side 17 of the bearing 10. A similar seal 15 (not shown) could be fitted to extend between the rings 11,12 at the opposite outer side of the bearing 10. The seal 15 has a body 18 acting as a filter to permit a flowable lubricant to pass through the body 18 to enter the interior of the bearing (arrow L) whilst preventing the ingress of

contaminants. In this embodiment, the inner ring 12 is intended to rotate while the outer ring 11 remains stationary but the outer ring 11 can rotate and the inner ring 12 can be held stationary. A holding member 19 which may be made from a resilient elastomer is molded around an axial end portion of the body 18 and serves to retain the seal 15. As shown, the member 19 is fitted into a groove 20 in the outer stationary ring 11. A sealing member 21 which may again be made from a resilient elastomer is molded onto the end region of the body 18 opposite the holding member 19.

The sealing member 21 also fits in a complementary groove 22 in the inner rotatable ring 12.

The sealing member 21 here has a bi-furcated end region defining sealing lips 23,24. The lip 23 is in rubbing contact with an outer axial surface 25 of the ring 12 bordering the groove 22 whilst the lip 24 is in rubbing contact with a flank wall surface 26 of the groove 22.

During use of the bearing incorporating a pair of seals 15 as described at opposite sides 17 of the bearing 10, flowable lubricant can be passed through the filter bodies 15 into and out from the interior of the bearing periodically or continuously. In the latter case the bearing can be more effectively cooled by re-circulating the lubricant through a heat exchanger. At high temperatures when the lubricant expands the filter bodies 18 act to relieve the pressure within the interior of the bearing. The bodies 18 can be made from a folded mesh and the porosity of the mesh can be chosen to suit a particular application.

Figure 2 shows a rolling element bearing 10 incorporating a pair of seals 15 and representing another embodiment of the invention. For convenience, like reference numerals are used to designate the same components as in Figure 1. Additionally represented in Figure 2 are one of the rolling elements in the form of a ball 9 and a cage 8 serving to maintain separation of the balls 9. In contrast to the seal 15 in Figure 1, the seals 15 in Figure 2 are additionally provided with metallic stiffening members 27 on the inside of the seals 15. The stiffening members 27 each have a lip 28 forming part of the holding member 19 which engages on an axial shoulder 39 of the groove 20. The holding member 19 and the sealing member 21 of each seal 15 are joined by outer radial wall portion 29 and so these regions 19,29 of the seal 15 are formed from an integral molded resilient elastomer. The sealing member 21 is also formed integral with the wall portion 29. Each seal 15 has one or several filter bodies 18 of planar form extending axially through the seal 15 and co-planar with the outer face of the wall portion 29 and with the inner face of the stiffening member 27. In this arrangement, the innermost lip 24 of the sealing member 21 of each seal makes rubbing contact with the inner flank wall surface 26 of the groove 22 while the outermost lip 23 terminates closely adjacent to an angularly inclined outer flank wall surface 30 of the groove 22. Since the seal 15 is resiliently deformable, the lip 23 can contact the outer flank wall surface 30 on axial displacement of the sealing member 21. The sealing member 21 also has recesses 33 adjacent the lips 24,23 with a narrow web 34 therebetween. Further sealing lips 35, 36 are defined by the recesses 33 to project axially inwardly and outwardly of the seal 15. In contrast to the seal 15 in the Figure 1 embodiment the sealing member 21 in the Figure 2 embodiment allows some lubricant to flow to or from the bearing interior independently of the filter body or bodies 18 as the sealing lips 24,23 can establish a small gap with respect to their associated sealing surfaces 30,26. The bearing 10 and the seals 15 shown in Figure 2 are particularly useful in applications where the supply of lubricant to the bearing interior is not effected through the filter bodies 18. The bearing lubrication can be achieved by the provision of a lubricant supply passage 40 so clean lubricant is introduced into the bearing and is then allowed to escape via the filter body or bodies 18. A bearing of this configuration is particularly useful in applications such as a continuously variable transmission unit where the lubricant in the unit forms the transmission fluid and must be free of contaminants. Trapping contaminants generated in the bearing 10 itself is acceptable.

In Figure 3 the bearing 10 incorporates only one seal 15 constructed in accordance with the invention The sealing member 21 of the seal 15 is the same as in Figure 2 but the stiffening member 27 is of annular configuration bridging the molded resilient elastomeric sealing member 21 with the filter body 18 which has an angular region 31 leading to a terminal region 32 acting as the holding member 19 of the seal 15. A further stiffening ring 33 is provided on the inside of the terminal region 32 and abuts on the inner flank surface 34 of the reception groove 20. As before the holding member 19 is press-fitted in the groove 20. The provision of the filter body 18 extending to the groove 20 is useful in certain applications where the flow of lubricant is influenced by gravity. A certain quality of lubricant can be maintained within the bearing by controlling the porosity of the filter body 18. In general, the filter body or bodies 18 used in the aforedescribed seals 15 are such as to pass particles under 10 micrometers in size and to trap larger particles.

Claims

CLAIMS 1. A rolling element bearing composed of relatively rotatable inner and outer rings with rolling elements therebetween and at least one seal which establishes a barrier between the rings wherein the seal is of composite form with at least one filter body or region permitting the passage of lubricant through the barrier while inhibiting the passage of contaminants through the barrier and with sealing means which is at least partly received in a groove in the rotatable ring ; the sealing means having separate sealing lips extending in different axial directions.
2. A bearing according to claim 1, wherein the sealing lips establish rubbing contact with the rotatable ring at a flank wall surface of the groove and at an axial surface bordering the groove and extending to an outer side face of the rotatable ring.
3. A bearing according to claim 1 or 2, wherein the seal has a holding member which fits into a groove in the stationary ring and retains the seal in place.
4. A bearing according to claim 1,2 or 3, wherein the sealing means is composed, at least partly, of an elastomeric body with a bi-furcated end region forming the sealing lips.
5. A bearing according to claim 3, wherein the holding member is at least partly formed as an elastomeric body and the holding member and the sealing means are separated by the filter body.
6. A bearing according to claim 1, wherein the seal further comprises a metallic stiffening member.
7. A bearing according to claim 3, wherein the seal has an elastomeric body with one end region forming the holding member, another end region forming the sealing means and a radial wall portion joining the holding member and the sealing means.
8. A bearing according to claim 7, wherein the filter body or bodies lie within the radial wall portion of the elastomeric body.
9. A bearing according to claim 8, wherein the filter body or each filter body is co-planar with the outer face of the radial wall portion of the elastomeric body.
10. A bearing according to any one of claims 7 to 9, wherein the seal has a metallic stiffening member extending alongside the radial wall portion of the elastomeric body.
11. A bearing according to claim 10, wherein the stiffening member has a lip forming part of the holding member.
12. A bearing according to claim 10 or 11, wherein the stiffening member has a radial inner surface facing the interior of the bearing and the or each filter body is co-planar with the radial inner surface of the stiffening member.
13. A bearing according to claim 3, wherein the sealing means is formed from an elastomeric body at one end of the seal and the filter body forms a radial wall portion of the seal and at least part of the holding member.
14. A bearing according to claim 13, wherein there is a metallic stiffening member joining the elastomeric body to the filter body.
15. A bearing according to any one of claims 7 to 15, wherein one of the sealing lips is in rubbing contact with one of the flank walls of the groove in the rotatable ring and the other of the sealing lips is closely adjacent the other of the flank walls of the groove.
16. A bearing according to claim 15, wherein the sealing means has recesses adjacent the sealing lips and defining additional sealing lips directed axially inwardly and outwardly of the bearing outside the groove.
17. A bearing according to any one or more of the preceding claims and incorporating two said seals one at either side of the bearing.
18. A bearing according to any one or more of the preceding claims, wherein a passage for supply of lubricant is provided in the stationary ring.
19. A composite seal for use in a bearing according to any one of the preceding claims and composed of at least one filter body made from a porous material for permitting the passage of lubricant while trapping contaminant particles, a holding member at one radial end region of the seal which serves to retain the seal in place by fitment into a groove in one of the bearing rings and a sealing member at the other opposite radial end region of the seal which is receivable at least partly in a groove in the other of the bearing rings and establishes sealing relationship with the other of the bearing rings with the aid of separate sealing lips extending in different axial directions.
20. A rolling element bearing or a composite seal therefor substantially as described herein with reference to, and as illustrated in, any one of the Figures of the accompanying drawing.