GB2151719A

GB2151719A - A sealing assembly for a bearing

Info

Publication number: GB2151719A
Application number: GB08431238A
Authority: GB
Inventors: Hubert Walter Thomas Neal
Original assignee: Svenska Kullagerfabriken AB
Current assignee: SKF AB
Priority date: 1983-12-21
Filing date: 1984-12-11
Publication date: 1985-07-24
Also published as: GB8333985D0; GB2151719B; IT8424076A1; IT1177426B; DE3446114A1; GB8431238D0; IT8424076A0

Abstract

A seal for a ball bearing comprises an annular housing (26), an annular support member (27) inside the housing, and a sealing ring (28) mounted on the support member and having a lip (38) in sliding sealing contact with an annular seal washer (31) integral with the annular housing (26). The sealing ring is disposed between the seal washer and an end wall (37) of the support member (27), and the housing has lips (41) on diametrically opposite portions of the housing, the lips overlapping the end wall of the support member in the radial direction and on the side opposite the seal washer so that the members of the seal form a self-contained unit. <IMAGE>

Description

SPECIFICATION Seals for bearings This invention relates to a seal for sealing an annular recess between two co-axial components rotatable relative to one another by a bearing in the recess.

It is known, for example from British patent specification 1 510 868, to provide a seal for the annular recess between two co-axiai components, comprising two annular members one of which is adapted to be mounted in the recess as a close fluid-tight fit on one of the components and the other of which is adapted to be mounted in the recess as a close fluid-tight fit on the other component, and a sealing ring of resilient material mounted on one of the members, the sealing ring being in sliding sealing contact with a disc-shaped seal washer integral with or secured to the other member. The individual members of a seal of this kind are generally fitted separately into the annular recess, and care and skill is necessary to ensure that no foreign matter enters the seal during assembly and that the members are assembled correctly within the recess.

The object of the invention is to provide a seal of the above described kind which is easier to fit into an annular recess, but which can nevertheless provide a satisfactory seal performance.

According to the invention there is provided a seal of the kind described, wherein the member fitted with the sealing ring has an end wall facing the seal washer, the sealing ring being disposed between the end wall and the seal washer, and a part of the member fitted with the seal washer overlaps said end wall in the radial direction and on the side thereof remote from the seal washer so that the two members are combined in a self contained unit prior to fitting the seal into the annular recess to be sealed. Preferably, one of the two members of the seal is deformable into a position in which the overlapping parts thereof are spaced radially from one another to permit the members to be axially separated, or assembled together.

In a preferred construction of the seal of the invention, the member fitted with the sealing ring (hereinafter referred to as the inner member) is mounted inside the member fitted with the seal washer (hereinafter referred to as the outer member), and the outer member is provided with one or more lips which overlap the periphery of the end wall on the inner member in the radial direction and on the side of the end wall remote from the seal washer, the lip or lips retaining the members of the seal in an assembled condition while the outer member remains in an unstressed condition, and the outer member is deformable into an oval shape in which the lip or lips are displaced radially outwards beyond the periphery of the end wall on the inner member to permit the inner member to be axially removable from the outer member, or assembled therewith.

In this construction of the seal of the invention, the inner member preferably has a cylindrical wall which extends with small clearance through the bore of the disc-shaped seal washer on the outer member so as to maintain the two members substantially co-axial prior to fitting of the seal into the annular recess to be sealed. This arrangement has the advantage that the two members are maintained substantially co-axial to one another prior to fitting of the seal into the annular recess. Alternatively, the inner member of the seal may have a cylindrical wall which extends through the bore of the disc-shaped seal washer on the outer member, and the inner periphery of the seal washer is formed with an annular lip in sealing contact with the cylindrical wall.This arrangement has the additional advantage that it provides two separate sealing barriers between the two members, as well as centering the two members relative to one another.

The seal of the invention is particularly suitable for use with a ball or roller bearing having an outer bearing ring adapted to be mounted on one of the components and an inner bearing ring adapted to be mounted on the other component. The outer member of the seal is then preferably mounted on the outer bearing ring, for example by claws on the outer member engaged in an annular groove in a periphery of the outer bearing ring, and the inner member of the seal arranged to abut against the inner bearing ring when the bearing and seal are mounted in position in the recess between the two components.

A ball or roller bearing fitted with a seal according to the invention is particularly suitable for use in an end cap of a conveyor roller. The bearing and seal assembly is easy.to fit onto a shaft and into a bore in the end cap, but nevertheless provides effective sealing. Moreover the assembly may be of short axial length.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross section through a bearing and seal assembly according to the invention, Figure 2 is a view of part of the bearing and seal assembly taken in the direction of the arrow X in Figure 1, Figure 3 is a view similar to Figure 2 of part of a modification of the bearing and seal assembly of Figures 1 and 2, Figures 4 and 5 shows the fitting of the bearing and seal assembly of Figure 1 onto a shaft and into an end cap of a conveyor roller, and Figure 6 shows, on an enlarged scale, a detail of another modification of the bearing and seal assembly of Figure 1.

The ball bearing of the assembly shown in Figure 1 comprises an outer bearing ring 10, an inner bearing ring 11, balls 12 in rolling engagement with tracks on the two bearing rings, and a cage 13 spacing the balls around the rings. The outer periphery of the outer bearing ring is formed on each side with an annular groove 15, and the part of the bearing ring between each groove 15 and the adjacent side of the bearing ring is cut away to form an annular flange 16 of smaller diameter than the re mainder of the periphery of the bearing ring.

The right hand side of the bearing as shown in Figure 1 is fitted with an annular seal 20 of known construction. The seal 20 is moulded in resilient plastics material and comprises an annular disc formed with an annular axially projecting claw 21 which is engaged as a snap fit in the groove 15 on the adjacent side of the outer bearing ring. The periphery of the seal 20 is substantially flush with the outer periphery of the outer bearing ring 10, and the seal 20 extends radially inwards across the annular gap between the two bearing rings. The seal 20 does not form part of the present invention.

The left hand side of the bearing as shown in Figure 1 is fitted with a seal 25 comprising an annular housing 26 moulded in resilient plastics material, an annular support member 27 made of metal, and a sealing ring 28 made of rubber or like material. The housing 26 has a cylindrical wall 30 and an annular flat wall 31 formed integral with the wall 30 adjacent the axially inner end thereof, that is the end adjacent the ball bearing.The wall 31 is engaged flat against the side of the outer bearing ring 10 and forms a seal washer, and the inner end of the cylindrical wall 30 terminates in an axial flange 32 having an inwardly projecting lip, the flange 32 being sub-divided by axial slots to form flexible claws 33 which are engaged as a snap fit in the annular groove 15, the outer periphery of the cylindrical wall 30 being substantially flush with the outer periphery of the outer bearing ring 10. The support member 27 is substantially of L shaped cross section and has a cylindrical wall 36 the end of which extends into the bore formed by the inner periphery of the wall 31 forming the seal washer and an annular end wall 37 the outer radially end of which is spaced from the inner surface of the wall 30 of the housing 26.The wall 37 of the support member is inclined axially inwards at a small angle towards the ball bearing. The sealing ring 28 is a radial interference fit on the support member at the junction between the walls 36, 37 and has an annular lip 38 which is in sealing sliding contact with the seal washer formed by the wall 31 of the housing. The sealing ring 28 may if desired be moulded onto the support member.

The clearance 40 between the cylindrical wall 36 of the support member and the inner periphery of the seal washer 31 is very small so that the support member is held substantially concentric within the housing. Also, the axially outer end of the housing, that is the end remote from the bearing, is formed with two arcuate lips 41 at diametrically opposite portions of the housing (only one of the lips 41 is shown in Figure 2). The internal diameter A (Fig. 2) across the lips 41 is less than the exter nal diameter B of the wall 37 of the support mem ber.The size difference between these diameters, and also the difference between the external diameter B of the wall 37 and the internal diameter C of the housing is such that the support member can be inserted axially into the housing or withdrawn when the housing has been deformed into an oval shape with the major axis of the oval passing through the centres of the lips 41. The almost concentric mounting of the support member 27 by the seal washer 31 enables the support member to be retained axially in the housing by a relative small difference between the external diameter of the support member and the internal diameter across the lips 41, provided that the housing is not deformed, that is while the housing is cylindrical in cross section.

The clearance between the external periphery of the wall 37 of the support member and the internal surface of the housing is preferably kept relatively small to exclude foreign matter from the interior qf the housing.

Figure 3 shows part of a modification of the bearing and seal assembly of Figures 1 and 2 in which the two arcuate lips 41 are replaced by two pairs of lips 42a disposed one pair on each of diametrically opposite portions of the housing with the two lips 41a of each pair of lips disposed symmetrically one on each side of a plane Y-Y passing diametrically through the axis of the housing (only one pair of the lips 41a is shown in Figure 3).The internal diameter A across the lips 41a is less than the external diameter B of the wall 37 of the support member, and the size difference between these diameters, the spacing between the two lips 41a at each of the diametrically opposite portions of the housing, and also the difference between the external diameter B of the wall 37 and the internal diameter C of the housing is such that the support member can be inserted axially into the housing or withdrawn when the housing has been deformed into an oval shape with the major axis of the oval co-incident with the axial plane Y-Y.As in the arrangement of Figure 2, the almost concentric mounting of the support member 27 by the seal washer 31 enables the support member to be retained axially in the housing by a relatively small difference between the external diameter B of the support member and the internal diameter A across a corresponding two of the lips 41a, provided that the housing is not deformed.

Figure 4 shows the bearing and seal assembly of Figure 1 lined up for mounting onto a spindle 45 and into the bore 47 of an end cap 46 of a con- veyor roller. The bearing and seal assembly is designed so that the inner bearing ring 11 is a sliding fit on the spindle 45, the outer bearing ring 10 is an interference fit in the bore 47, the housing 26 is a fluid tight fit against the surface of the bore 47, and the support member 27 is a fluid tight fit against the surface of the spindle.

As shown in Figure 4 a dolly 50 is used to apply an axial mounting force to the bearing and seal assembly, the dolly having annular surfaces in contact with the housing 26 and the support member 27. The assembly is initially mounted on the spin dle and the axial force is applied through the support member 27 of the assembly. The almost concentric mounting of the support member 27 within the housing 26, due to the small clearance between the bore of the seal washer and the cylindrical wall of the support member, and the concentric mounting of the housing on the outer bearing ring ensures that the bore in the support member is substantially co-axial with the bore in the bearing and this feature facilitates fitting of the support member on the spindle.

When the bearing and seal assembly reaches the bore 47 in the end cap, the axial mounting force is applied by the dolly simultaneously to the housing 26 and the support member 27 of the assembly.

Figure 5 shows the bearing and seal assembly mounted in position in the bore of the end cap and on the spindle. The assembly is retained axially in position on the spindle by a circlip 51 mounted in a groove 52 in the spindle.

Figure 6 shows part of a modification of the bearing and seal assembly of Figure I in which the wall 31 of the housing which forms a seal washer is provided on its inner periphery with an annular lip 60 which, in an unstressed condition prior to assembly of the seal, projects radially inwards and defines a bore having a diameter less than that of the external diameter of the cylindrical wall 36 of the support member 27. Upon assembly of the support member 27 into the housing 26, the cylindrical wall 36 deflects the lip 60 into the position shown in Figure 6 in which a side of the lip 60 makes contact with the cylindrical wall 36 around its full periphery. This construction has the advantages that the annular lip 60 centres the support member relative to the housing prior to fitting of the seal onto a spindle, and the annular lip 60 also provides a sealing barrier between the housing and the support member which is additional to the sealing barrier provided by the sealing ring 28.

Claims

CLAIMS:

1. A seal for sealing an annular recess between two co-axial components rotatable relative to one another by a bearing in the recess, the seal comprising two annular members one of which is adapted to be mounted in the recess as a close fluid-tight fit on one of the components and the other of which is adapted to be mounted in the recess as a close fluid-tight fit on the other component, and a sealing ring of resilient material mounted on one of the members, the sealing ring being in sliding sealing contact with a disc-shaped seal washer integral with or secured to the other member, characterised in that the member (27) fitted with the sealing ring (28) has an end wall (37) facing the seal washer (31), the sealing ring (28) being disposed between the end wall (37) and the seal washer (31), and a part (41) of the member (26) fitted with the seal washer (31) overlaps said end wall (37) in the radial direction and on the side thereof remote from the seal washer (31) so that the two members (26, 27) are combined in a selfcontained unit prior to fitting the seal into the annular recess to be sealed.

2. A seal as claimed in claim 1, characterised in that one of said members (26, 27) is deformable into a position in which the overlapping parts thereof (41, 37) are spaced radially from one another to permit the members (26, 27) to be axially separated from one another.

3. A seal as claimed in claim 2, in which the member fitted with the sealing ring is mounted inside the member fitted with the seal washer, characterised in that the outer member (26) fitted with the seal washer (31) is provided with one or more lips (41) which overlap the periphery of said end wall (37) in the radial direction and on the side of the end wall (37) remote from the seal washer (31), the said lip or lips (41) retaining the members of the seal in an assembled condition while the outer member (26) remains in an unstressed condition, and the outer member (26) is deformable into an oval shape in which the lip or lips (41) are displaced radially outwards beyond the periphery of the end wall (37) on the inner member (27) to permit the inner member (27) to be axially removable from the outer member (26).

4. A seal as claimed in claim 3, characterised in that the outer member (26) is formed with two of said lips (41) disposed one on each of diametrically opposite portions of the outer member (26), each lip being arcuate and the internal diameter (A) across the lips being less than the external diameter (B) of the end wall (37) of the inner member (27).

5. A seal as claimed in claim 3, characterised in that the outer member (26) is formed with two pairs of said lips (41a) disposed one pair on each of diametrically opposite portions of the outer member (26) with the two lips (41a) of each pair of lips disposed one on each side of a plane passing diametrically through the axis of the outer member (26), the internal diameter (A) across corresponding lips (41a) being less than the external diameter (B) of the end wall (37) of the inner member (27).

6. A seal as claimed in claim 3, 4 or 5, characterised in that the outer member (26) is moulded in resilient plastics material and comprises a cylindrical wall (30) and an annular flat wall (31) inside the cylindrical wall (30) and formed integral with the cylindrical wall adjacent one end thereof, said flat wall (31) forming the annular seal washer, and said lips (41: 41a) are formed on the end of the cylindrical wall (30) remote from the seal washer (31), the lips projecting radially inwards and overlapping the end wall (37) of the inner member (27) on the side thereof remote from the seal washer (31).

7. A seal as claimed in any of claims 3-6, characterised in that the inner member (27) has a cylindrical wall (36) which extends with small clearance through the bore of the disc-shaped seal washer (31) on the outer member (26) so as to maintain the two members (28, 27) substantially co-axial prior to fitting of the seal into the annular recess to be sealed.

8. A seal as claimed in any of claims 3-6, characterised in that the inner member (27) has a cylindrical wall (36) which extends through the bore of the disc-shaped seal washer (31) on the outer member (26), and the inner periphery of the seal washer (31) is formed with an annular lip (60) in sealing contact with the cylindrical wall (36).

9. A seal as claimed in any of claims 3-8 and fitted on a ball or roller bearing having an outer bearing ring and an inner bearing ring, characterised in that the outer periphery of the outer bearing ring (10) is formed with an annular groove (15), and the outer member (26) of the seal is formed at one end thereof with claws (33) which are engaged in said groove (15), and the inner member (27) of the seal abuts against the inner bearing (11).

10. A seal for sealing an annular recess between two co-axial components rotatable relative to one another by a bearing in the recess substantially as hereinbefore described with reference to Figures 1 and 2, or Figures 1 and 3, or Figures 1 and 6 of the accompanying drawings.