GB2225066A

GB2225066A - Seal assembly

Info

Publication number: GB2225066A
Application number: GB8925794A
Authority: GB
Inventors: Bogdan Bogdanovic
Original assignee: Ha Rubber & Plastics
Current assignee: Ha Rubber & Plastics
Priority date: 1988-11-16
Filing date: 1989-11-15
Publication date: 1990-05-23
Anticipated expiration: 2009-11-15
Also published as: GB8925794D0; GB2225066B

Abstract

A seal assembly includes a boss 12 locatable on a shaft 14, with a radially extending flange 16 on the boss. An outer shell 18 is rotatably mounted co-axially relative to the boss and axially inwardly of the flange. The outer shell has a radially inwardly directed skirt 20 co-operating with an inner face of the flange on the boss and forming a contact seal in light sealing contact with the inner face of the flange. There is a labyrinth seal between the contact seal and a ball bearing 40. A tubular conveyor roller engages the outside of the ball bearing and the outer shell 18. <IMAGE>

Description

SEAL ASSEMBLY This invention relates to a seal assembly. It relates particularly, but not necessarily exclusively, to a seal assembly intended for use in a conveyor roller.

According to the invention there is provided a seal assembly which includes a boss locatable on a shaft, a radially extending flange on the boss, and an outer shell rotatably mounted co-axially relative to the boss and axially inwardly of the flange, the outer shell having a radially inwardly directed skirt cooperating with an inner face of the flange on the boss and forming a contact seal in light sealing contact with the inner face of the flange.

The skirt may have an axially outwardly directed and circumferentially extending nose thereon forming the contact seal in light sealing contact with the inner face of the flange on the boss.

The nose may conveniently be V-shaped in cross-section to make light line contact with the inner face.

The outer shell may have an axially outwardly extending portion co-axial with the boss and forming a base for the skirt. The skirt may taper radially outwardly and be broader at its radially outermost end where it is attached to the axially outwardly extending portion of the outer shell.

The flange on the boss may have a set therein with its outer extremity bent inwardly towards the skirt. One face of the skirt may extend in axially spaced substantially parallel relationship to the flange and its set, thereby forming a V-shaped channel between said face and the inner face of the flange.

The outer shell may have a partition depending radially inwardly therefrom axially inwardly of the skirt. The partition may be L-shaped in cross section with its radially inner end extending in closely spaced co-axial relationship with the boss.

The outer shell may have an axially inwardly protruding portion co-axial with the boss and providing an inner base for supporting one half of a labyrinth seal located axially inwardly of the flange. An opposite half of the labyrinth seal may be located on an outer periphery of an extension of the boss. The respective halves of the labyrinth seal may comprise at least one pair of mating seal members arranged in staggered relationship on the extension of the boss and the inner base of the axially inwardly protruding portion of the outer shell respectively. A plurality of pairs of such seal members may be arranged in axially stacked relationship.

The seal members on the outer shell may have bases which are retained axially between the partition and a lug provided on the base of the outer shell. Similarly, the seal members on the boss may be retained axially between a lug and a step provided on the outer periphery of the boss.

The outer shell may have on its outer surface a radially outwardly extending lip forming a stop for a tubular conveyor roller.

The seal assembly may further include a bearing having inner and outer ball races axially inwardly of the seal assembly.

The bearing may be a standard ball bearing and have side caps thereon for retaining a lubricant for lubricating the bearing. At; least one of the side caps may define an enlarged circumferentially extending annular trough for containing the lubricant.

An embodiment of the invention is now described by way of example with reference to the accompanying drawing, in which an axial section through a seal assembly in accordance with the invention is shown.

Referring to the drawings, reference numeral 10 generally indicates a seal assembly which includes a boss 12 locatable on a shaft 14. The boss 12 has a radially extending flange 16. An outer shell 18 is rotatably mounted coaxially relative to the boss 12 and axially inwardly of the flange 16. The outer shell 18 has a radially inwardly directed skirt 20 which has a pointed nose 22 co-operating with an inner face 24 of the flange 16 to form a contact seal.

The outer shell 18 has an axially outwardly extending portion 18.1 which forms a base for the skirt 20. The skirt has a broad base where it is attached to the portion 18.1 to provide sufficient resilience in the skirt 20. The junction 26 between the base of the skirt 20 and the portion 18.1 is corrugated to retain the skirt within the portion 18.1. The skirt 20 is a force fit during assembly in the portion 18.1.

The flange 16 has an inwardly bent set 28 and the opposed face of the skirt 20 is shaped matingly to define a circumferentially extending channel 30 which is V-shaped in cross section. Any dirt which may enter the channel 30 will thus tend to be thrown outwardly from the channel 30 when the outer shell 18 is rotated.

The outer shell 18 has a partition 32 of L-shape in cross section depending radially inwardly therefrom and axially inwardly of the skirt 20. The partition 32 provides additional support in an axial direction for the skirt 20 and also has its radially inner end 32.1 in closely spaced co-axial relationship with the boss 12.

The outer shell 18 has an axially inwardly protruding portion 18.2 coaxial with the boss 12 and providing an inner base 34 for supporting one half of a labyrinth seal formed by a plurality of seal members 36 which are also L-shaped in cross section.

Similar seal members 38 are provided in staggered relationship with the seal members 36 on the outer.periphery of the boss 12. The seal members 36 and 38 being in closely spaced relationship together with the close spacing between the radially inner end 32.1 of the partition 32 and the boss 12 define a tortuous path making ingress of dirt towards a bearing 40 difficult.

The seal members 36 are retained in axially stacked relationship within the outer shell 18 between the partition 32 and a lug 42. Similarly the seal members 38 are retained in axially stacked relationship on the outer periphery of the boss 12 between a lug 44 and a step 46 provided on the outer periphery of the boss 12.

The outer shell 18 has on its outer surface a radially outwardly extending lip 48 forming a stop for receiving the end of a tubular conveyor roller (not shown). The outer surface of the outer shell may have a plurality of raised ribs thereon (not shown) providing an interference fit between the outer shell and the conveyor roller.

The seal assembly further includes a standard ball bearing 40 having an inner race 50 and an outer race 52. The bearing 40 has side caps 54 for retaining a lubricant for lubricating the bearing 40. In this embodiment, both side caps 54 define an enlarged circumferentially extending annular trough 56 for containing the lubricant.

The bearing 40 is retained in position by a circlip 58.

The invention illustrated provides a seal assembly particularly suited for conveyor rollers and wherein there is provided a bearing with enlarged lubricant troughs 56 to enable a standard ball bearing to be used instead of an expensive sealed bearing. The applicant believes that dirt will not readily reach the bearing 40 by reason of the labyrinth seal formed by the L-shaped seal members 36 and 38 and by the partition 32 and the boss 12. It is also difficult for dirt to enter the bearing 40 by reason of the contact seal formed by the nose 22 on the skirt 20 contacting the flange 16. The seal assembly can be readily inexpensively manufactured predominantly from synthetic plastics.materials. The seal assembly provides a minimum of friction as the only friction is provided by the line contact between the pointed nose 22 and the flange 16. Consequently, when used on a long conveyor roller, relatively little start up power is required after the conveyor has been brought to a standstill.

Claims

1. A seal assembly which includes a boss locatable on a shaft, a radially extending flange on the boss, and an outer shell rotatably mounted co-axially relative to the boss and axially inwardly of the flange, the outer shell having a radially inwardly directed skirt cooperating with an inner face of the flange on the boss and forming a contact seal in light sealing contact with the inner face of the flange.

2. A seal assembly as claimed in claim 1, in which the skirt has an axially outwardly directed and circumferentially extending nose thereon forming the contact seal in light sealing contact with the inner face of the flange on the boss.

3. A seal assembly as claimed in claim 2, in which the nose is V-shaped in cross-section to make light line contact with the inner face.

4. A seal assembly as claimed in any one of the preceding claims, in which the outer shell has an axially outwardly extending portion co-axial with the boss and forming a base for the skirt, the skirt tapering radially outwardly and being broader at its radially outermost end where it is attached to the axially outwardly extending portion of the outer shell.

5. A seal assembly as claimed in any one of preceding claims, in which the flange on the boss has a set therein with its outer extremity bent inwardly towards the skirt, and in which one face of the skirt extends in axially spaced substantially parallel relationship to the flange and its set, thereby forming a channel which is V-shaped in cross section between said face and the inner face of the flange.

6. A seal assembly as claimed in any one of the preceding claims, in which the outer shell has an L-shaped partition depending radially inwardly therefrom axially inwardly of the skirt with its radially inner end in closely spaced co-axial relationship with the boss.

7. A seal assembly as claimed in any one of the preceding claims, in which the outer shell has an axially inwardly protruding portion co-axial with the boss and providing an inner base for supporting one half of a labyrinth seal located axially inwardly of the flange, an opposite half of the labyrinth seal being located on an outer periphery of an extension of the boss.

8. A seal assembly as claimed in claim 7, in which the respective halves of the labyrinth seal comprise at least one pair of mating seal members arranged in opposed staggered relationship on the extension of the boss and the inner base of the axially inwardly protruding portion of the outer shell respectively.

9. A seal assembly as claimed in claim 8, in which a plurality of pairs of individual seal members are arranged in axially stacked relationship.

10. A seal assembly as claimed in any one of the preceding claims, which further includes a bearing having inner and outer ball races axially inwardly of the seal assembly, the bearing being in the form of a standard ball bearing having side caps thereon for retaining a lubricant for lubricating the bearing.

11. A seal assembly substantially as described and as illustrated herein.