WO2011083303A1

WO2011083303A1 - Bearing

Info

Publication number: WO2011083303A1
Application number: PCT/GB2010/052202
Authority: WO
Inventors: Martin Caspall; John Dickerson
Original assignee: Cooper Roller Bearings Co. Ltd.
Priority date: 2010-01-05
Filing date: 2010-12-23
Publication date: 2011-07-14
Also published as: GB2476721A; GB201021849D0; GB201000062D0

Abstract

A bearing apparatus (10) for supporting a rotatable shaft (14), said bearing apparatus comprising an outer housing (12) supporting the bearing apparatus and an inner housing (11) which encloses bearing elements (19 ) comprising balls or rollers surrounding the shaft (14), a part spherical seat (28) being provided between the inner and outer housing to withstand dynamic misalignment of the shaft and bearing apparatus by allowing rotational movement between the inner and outer housings, means being provided to pass lubricant from the outer housing to the inner housing, said means comprising a member (37) mounted in and protruding from one of the outer housing or inner housing to engage with a slot (41) in the other of the outer housing or inner housing, said protruding member and said slot being formed to allow limited movement of the protruding member in the slot caused by said rotational movement between the inner and outer housings, and means being provided to allow passage of lubricant from the slot to the bearing elements.

Description

BEARING

The present invention relates to bearings.

BACKGROUND TO THE INVENTION

There are particular problems in providing a bearing for heavy industrial use, for example, for supporting a rotatable shaft in severe conditions. Although not restricted thereto in the preferred example to be described, the bearing is for use with a scroll conveyor or auger for use in transporting coal or rock. Such a bearing frequently operates under a particularly severe combination of conditions - abundant and abrasive contamination, frequently dynamic misalignment of the shaft (by which we mean, inter alia, a misalignment between the shaft and the bearing which often occurs once per revolution when the shaft is not straight), heavy loading, and shock.

The present invention provides a bearing which reduces or overcomes these problems. SUMMARY OF THE INVENTION

A bearing of the invention includes an efficient lubrication system, and/or a mechanism which allows dynamic movement between an inner and an outer housing to compensate for dynamic shaft misalignment. The mechanism for compensating for shaft misalignment is preferably lubricated.

The present invention provides a bearing apparatus for supporting a rotatable shaft, said bearing apparatus comprising an outer housing supporting the bearing apparatus and an inner housing which encloses bearing elements comprising balls or rollers surrounding the shaft, a part spherical seat being provided between the inner and outer housing to withstand dynamic misalignment of the shaft and bearing apparatus by allowing rotational movement between the inner and outer housings, means being provided to pass lubricant from the outer housing to the inner housing, said means comprising a member mounted in and protruding from one of the outer housing or inner housing to

090209WO - Description filed PCT Dec.10 engage with a slot in the other of the outer housing or inner housing, said protruding member and said slot being formed to allow limited movement of the protruding member in the slot caused by said rotational movement between the inner and outer housings, and means being provided to allow passage of lubricant from the slot to the bearing elements.

Preferably there is provided means to limit relative rotation between the inner and outer housings in any direction, said means to limit said rotation comprising a member mounted in and protruding from one of the outer housing or inner housing to engage with a slot in the other of the outer housing or the inner housing.

Preferably said means to pass lubricant from the outer housing to the inner housing comprises said means to limit relative rotation between the inner and outer housings. Preferably said means to pass lubricant from the outer housing to the inner housing and said means to limit relative rotation between the inner and outer housing are spaced form one another around the circumference of the outer housing..

Preferably said means to pass lubricant from the outer housing to the inner housing and said means to limit relative rotation between the inner and outer housings are diagonally spaced form one another around the circumference of the outer housing..

Preferably the or each said protruding member protrudes from the outer housing and projects into a slot in the adjacent surface of the inner housing.

Preferably the means to limit relative rotation between the inner and outer housings, the slot is longer in a direction parallel to the axis of the shaft than at right angles thereto and includes two opposite long straight side surfaces parallel to the axis of the shaft. Preferably the two opposite long straight side surfaces allow the means to limit relative rotation between the inner and outer housings to slide along the straight side surfaces of

090209WO - Description filed PCT Dec.10 2 the slot, to allow for dynamic misalignment of the inner housing relative to the outer housing.

Preferably said means to limit relative rotation between the inner and outer housings comprises an anti-rotation peg.

Preferably means is provided to pass lubricant to a spherical seat between the inner and outer housings, lubricant being held between spherical surfaces on the inner and outer housings which forms the spherical seat.

Preferably circular seals are provided extending between the spherical surfaces adapted to hold the lubricant between the inner and outer housings.

Preferably grooves are provided in one or both spherical surfaces to distribute lubricant around the spherical seat to reduce wear on the spherical surfaces.

Preferably seal means is provided to keep the lubricant lubricating the spherical seat and the lubricant lubricating the bearing elements separate, said seal means comprising a seal extending around the means to pass lubricant from the outer housing to the inner housing, whereby different lubricants may used and/ any contamination of one lubricant by the other is reduced.

Preferably sealing of the bearing itself is provided by a combination of twin radial seals, with an additional barrier being provided by the whole housing sitting in a recess between shoulders in the shaft.

Preferably there is provided a lubricant relief valve to allow purging of lubricant through the bearing elements.

BRIEF DESCRIPTION OF THE DRAWINGS

090209WO - Description filed PCT Dec.10 3 Preferred embodiments of bearing apparatus according to the invention will now be described by with reference to the accompanying drawings in which;-

Figure 1 is a view, partly in section, along the axis of a bearing apparatus according to the invention,

Figure 2 is a vertical axial section of the bearing apparatus of Figure 1,

Figure 3 is a plan view of the bearing apparatus of Figure 1 ,

Figure 4 is a cross section of a hollow anti-rotation peg and slot in which it sits,

Figure 5 is a cross-section of an alternative, solid, anti-rotation peg and slot, Figure 6 is a view, partly in section, along the axis of a bearing apparatus according to a second embodiment of the invention, and

Figure 7 is a vertical axial section of the bearing apparatus of Figure 6. The bearing apparatus according to a preferred aspect of the invention comprises a roller bearing apparatus 10 comprising an inner housing 11 and an outer housing 12, the inner housing 11 comprising a cartridge 13. The roller bearing apparatus rotatably supports a shaft 14 (see Figure 2). The outer housing 12 comprises a pedestal mount 16 which, as is clear from Figure 1, is provided in two parts, a lower part 17 forming a suitable base, and an upper part 18 for enclosing the cartridge 13 between the upper and lower parts 18, 17.

The cartridge 13 encloses bearing elements 19 which is in this instance comprise rollers 21 mounted in a cage 22 for rotation between an inner race 23 and an outer race 24. In this way, the shaft 14 is allowed to freely rotate about its axis.

090209WO - Description filed PCT Dec.10 4 The shape of the outer surface of the cartridge 13 and the outer housing 12 is clear from Figure 2. The outer housing 12 includes an inner annular surface comprising a spherical surface 26 and the cartridge 13 similarly includes an outer annular surface comprising a spherical surface 27 of similar form, that is, radius and curvature, to the spherical surface 26. The two spherical surfaces 26, 27 form of spherical seat 28. In this way, the cartridge 13 may rotate slightly about the centre of curvature 29 of the spherical seat 28. This rotation allows for alignment of the bearing elements 19 with the shaft 14 during assembly, but also allows for rotation of the cartridge 13 about the centre of curvature 29 to compensate for dynamic misalignment of the shaft and bearing (i.e. to allow for a shaft which becomes distorted, that is the axis of the shaft lacks straightness and takes a curve, during use, or, indeed, during manufacture). Any curvature in the axis of the shaft will mean that the cartridge 13 needs to rotate slightly for every rotation of the shaft. To allow for this rotation, the spherical seat 28 preferably requires lubrication. Referring in particular to Figure 2, it will be seen that the outer spherical surface 26 includes two circular grooves 31,32, in which are mounted seals 33,34, the circular grooves being centred on the axis of the shaft. The inner spherical surface 26 includes grooves 36 for distributing lubricant across the surfaces of the spherical seat 28.

To prevent rotation about the axis of the shaft between the cartridge 13 and the outer housing 12, there is provided an anti rotation peg 37.

The peg 37 is mounted in a bore 38 in the spherical surface 26 of the base of pedestal 16, and the peg 37 itself is hollow having a bore 39 passing along its axial length. The anti rotation peg 37 extends into an opening or slot 41 (hereafter simply referred to as a slot) in or through the inner spherical surface 27, and there is provided a small bore 42 communicating the slot 41 with the inner race 23. Various bores are provided in the pedestal base 16 whereby lubricant in the form of grease may be passed from a grease nipple 43 through the bore 38, the bore 39 in the peg, the slot 41, and the bore 42 to allow lubricant to be passed to the bearing elements

090209WO - Description filed PCT Dec.10 5 including the rollers 21, and inner and outer races 23, 24. To prevent this lubricant passing to the spherical seat 28, there is an "O" ring 46 is mounted in a seat 47, the "O" ring 46 surrounding the anti rotation peg 37. A second grease nipple 48 is provided and is in communication with the various bores through the pedestal base, the bores having outlets 51, 52 which pass grease directly to the grooves 36 to thereby provide lubricant in the form of grease to the spherical seat 28. It will be understood that in this way, the lubricated spherical seat 28 allows a lubricated relative movement between the cartridge 13 which mounts the shaft 14, and the outer housing 12 which can compensate for a curvature in the axis of the shaft.

Furthermore, the provision of the seals 33, 34 prevents ingress of abrasive dust and the like into the spherical seat 28.

The bearing elements 19 are further protected from abrasive dust by (see Figure 2) mounting the outer housing 12 between shoulders 53, 54 of the shaft, thereby preventing abrasive dust and the like from easily getting to the bearing elements 19. The bearing elements are further protected by a pair of circular seals 56, 57 between the reduced outer circular surface 58 of the shaft 14 and an inner circular surface 59 of the outer housing 12.

The sealed compartment 61 in which the bearing elements 19 are mounted and which is full of grease provided by the first grease nipple 43, incorporates a relief valve 62 through which the lubricant or grease which is lubricating the bearing elements 19 may be purged from time to time by applying grease to the second grease nipple 48.

We now refer to the details of the rectangular slot 41 and the hollow anti rotation peg 37.

090209WO - Description filed PCT Dec.10 6 As it clear from Figure 1,2 and 4, the width w (14mm) of the slot 41 transverse the axis of the shaft is only slightly greater than the diameter d (10mm) of the anti rotation peg 37. This allows only limited rotation of movement of the cartridge 13 around the axis of the shaft 14. The slot has a length / (16mm) which is only slightly longer than it is wide, which is all that is needed to allow around 2 degrees of misalignment of the shaft which causes a small relative rotation between the inner housing 11 and the cartridge 13 about an axis transverse the shaft axis. It could be a lot closer fit on width, but we allow about 2mm either side to allow for a combination of position tolerances and wear in the spherical surfaces which may cause the pin to be off-centre from the slot.

The use of a the two straight surfaces in the slot allows the anti-rotation peg to slide along the straight sides of the slot, to allow for misalignment of the inner housing relative to the outer housing. This prevents a 'wringing' action on the peg, which can now work along the flat slide of the slot.

All of the seals are preferably of Kevlar braid around a polymeric core. The seals sealing around the spherical seat of the housing are preferably profiled to suit the shape of the surface they are sealing against. Whilst it is convenient to provide a hollow anti rotation peg 37 through which grease may pass, a separate grease supply may be provided alongside or elsewhere and the anti rotation peg may than be solid.

In the arrangement of Figures 1 to 3, the anti-rotation peg may be moved into the upper part of the housing, working in a 'blind' slot, with the lubricant supply being through simple holes in the inner and outer housing. This allows a larger slot to be formed for greater misalignment capability. (In the embodiment shown the slot is close to the '0' ring that separates the two lubricant systems, which is in turn close to the lubrication grooves formed in the spherical surface. This restricts the length of the slot). A further advantage of this arrangement is that if excessive misalignment should cause damage to the anti-rotation peg, any debris from this is unlikely to pass through to the bearing (whereas is can pass into the bearing with the lubricant in the embodiment shown).

090209WO - Description filed PCT Dec.10 7 Wee now refer to the alternative embodiment in Figures 5, 6 and 7.

Figures 6 and 7 are substantially identical to Figures 1 and 2, but there is an anti- rotation peg 65 and slot 66 between the cartridge 13 and the outer housing 12 at the top of the cartridge. The form of the anti-rotation peg 65 is shown in Figure 5.

As can be seen from Figure 5 the peg 65 is a solid peg of 8mm diameter and the slot (which is of a width 12mm) can be longer (24mm) than the slot 41. because it is not restricted by the O ring 46 which is required to keep the two grease paths separate. In this case, there is no grease path passing through the peg 65 and slot 66. As is clear from Figure 7, the slot is , in fact, a blind bore.

Because the difference between the dimensions of the slot and peg are larger in the lower peg/slot combination 37/41 than in the peg/slot combination 65/66, the peg 37 is able to move a greater distance in the slot and so the lower peg/slot combination 37/41 simply provides the lubricant path to the bearing elements including the rollers 2 land the upper peg/slot combination 65/66 acts as an anti-rotation peg The invention is not restricted to the details of the foregoing example.

For example, the anti rotation peg may extend out of the inner spherical surface 27 into a slot in the outer spherical surface 26.

090209WO - Description filed PCT Dec.10 8

Claims

CLAIMS:

1. A bearing apparatus for supporting a rotatable shaft, said bearing apparatus comprising an outer housing supporting the bearing apparatus and an inner housing which encloses bearing elements comprising balls or rollers surrounding the shaft, a part spherical seat being provided between the inner and outer housing to withstand dynamic misalignment of the shaft and bearing apparatus by allowing rotational movement between the inner and outer housings, means being provided to pass lubricant from the outer housing to the inner housing, said means comprising a member mounted in and protruding from one of the outer housing or inner housing to engage with a slot in the other of the outer housing or inner housing, said protruding member and said slot being formed to allow limited movement of the protruding member in the slot caused by said rotational movement between the inner and outer housings, and means being provided to allow passage of lubricant from the slot to the bearing elements.

2. A bearing apparatus as claimed in claim 1 in which there is provided means to limit relative rotation between the inner and outer housings in any direction, said means to limit said rotation comprising a member mounted in and protruding from one of the outer housing or inner housing to engage with a slot in the other of the outer housing or the inner housing.

3. A bearing apparatus as claimed in claim 2 in which said means to pass lubricant from the outer housing to the inner housing comprises said means to limit relative rotation between the inner and outer housings.

4. A bearing apparatus as claimed in claim 2 in which said means to pass lubricant from the outer housing to the inner housing and said means to limit relative rotation between the inner and outer housing are spaced from one another around the circumference of the outer housing..

090209WO - Claims filed PCT Dec.10 9

5. A bearing apparatus as claimed in claim 4 in which said means to pass lubricant from the outer housing to the inner housing and said means to limit relative rotation between the inner and outer housings are diagonally spaced form one another around the circumference of the outer housing..

6. A bearing apparatus for supporting a rotatable shaft as claimed in any of claims 1 to 5 in which the or each said protruding member protrudes from the outer housing and projects into a slot in the adjacent surface of the inner housing.

7. A bearing apparatus as claimed in claim 6 in which in the means to limit relative rotation between the inner and outer housings, the slot is longer in a direction parallel to the axis of the shaft than at right angles thereto and includes two opposite long straight side surfaces parallel to the axis of the shaft.

8. A bearing apparatus as claimed in claim 7 in which the two opposite long straight side surfaces allow the means to limit relative rotation between the inner and outer housings to slide along the straight side surfaces of the slot, to allow for dynamic misalignment of the inner housing relative to the outer housing.

9. A bearing apparatus as claimed in any of claims 1 to 8 in which said means to limit relative rotation between the inner and outer housings comprises an anti-rotation peg.

10. A bearing apparatus as claimed in any of claims 1 to 9 in which means is provided to pass lubricant to a spherical seat between the inner and outer housings, lubricant being held between spherical surfaces on the inner and outer housings which forms the spherical seat.

11. A bearing apparatus as claimed in claim 10 in which circular seals are provided extending between the spherical surfaces adapted to hold the lubricant between the inner and outer housings.

090209WO - Claims filed PCT Dec.10 10

12. A bearing apparatus as claimed in claim 10 or 11 in which grooves are provided in one or both spherical surfaces to distribute lubricant around the spherical seat to reduce wear on the spherical surfaces.

13. A bearing apparatus as claimed in any of claims 10 to 12 in which seal means is provided to keep the lubricant lubricating the spherical seat and the lubricant lubricating the bearing elements separate, said seal means comprising a seal extending around the means to pass lubricant from the outer housing to the inner housing, whereby different lubricants may used and/ any contamination of one lubricant by the other is reduced.

14. A bearing apparatus as claimed in any of claims 1 to 13 in which sealing of the bearing itself is provided by a combination of twin radial seals, with an additional barrier being provided by the whole housing sitting in a recess between shoulders in the shaft.

15. A bearing apparatus as claimed in any of claims 1 to 14 in which there is provided a lubricant relief valve to allow purging of lubricant through the bearing elements.

090209WO - Claims filed PCT Dec.10 11