GB2105797A

GB2105797A - Rotary shaft seal

Info

Publication number: GB2105797A
Application number: GB08127512A
Authority: GB
Inventors: Kenneth Roy Taylor
Original assignee: AEREQUIP
Current assignee: AEREQUIP
Priority date: 1981-09-11
Filing date: 1981-09-11
Publication date: 1983-03-30
Also published as: DE3233573A1; IT1152391B; IT8223210A0; FR2512913A1; ES282726U; ES282726Y; GB2105797B

Abstract

A rotary shaft seal has inner and outer shell members (13 and 12) which are substantially L-shaped in cross section and which secure between their radially extending legs a P.T.F.E. sealing member (20) and a friction washer (15). On the outer surface of the member (12) is provided a layer (11) of resilient material, which layer may extend radially inwardly on the radially extending leg of the shell member (12) and may terminate in a secondary sealing lip (21). The washer (15) can be formed integrally with the layer (11) and lip (21). <IMAGE>

Description

SPECIFICATION Rotary shaft seal This invention is concerned with rotary seals, which incorporate a sealing element made of polytetrafluroethylene (hereinafter referred to as P.T.F.E.).

Rotary seals incorporating P.T.F.E. sealing element are well known and are generaliy provided with a metal shell having an outside diameter that is either ground finished to a predetermined size or has a sealant applied thereto. These forms of finish are acceptable for those appiications which have housings, into which the seal is pressed, of substantial or robust construction.

Problems occur when the seals are required to be fitted into thin wall housings, particularly those of aluminium or aluminium alloy or where the housing is split in two parts for assembly and dismantling purposes.

The present invention is a rotary seal comprising an outer shell member, an inner shell member, a P.T.F.E. sealing element having a radially extending portion secured between radially extending portions of the inner and outer shell members, and a layer of resilient material bonded to the outer surface of the outer shell member.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, the five Figures of which each show a radial cross section of a rotary seal according to the present invention.

The seal of Figure 1 has an outer annular shell member 12 of substantially L-shaped cross section and on the radial extending leg 17 thereof are mounted a friction member or washer 15, and a radially extending portion 18 of a P.T.F.E. sealing member 14. The washer 15 and the member 14 are secured in a position by an inner annular shell member 13 of L-shaped cross section whose radially extending leg 19 overliesthe portion 18 ofthe sealing member and is pressed towards the leg 17 of the outer shell member by the top of the radial leg of the outer member 12 which is peened over. The function of the friction washer 15 is simply to prevent the sealing element turning in the shell, and to prevent leakage through the internal parts of the seal.

The sealing member 14 is in itself conventional and has a sealing lip 20 adapted to engage and seal against a rotary shaft passing through the seal.

On the outer surface of the outer shell member 12 is provided a layer of resilient material 11 which is bonded to the member 12 and which can be compressed and thus absorb the misalignments which can occur with split housing, thus protecting the shell members against distortion.

Typical suitable materials are the weli known rubbers and elastomers such as nitrile, polyacrylic, silicone orfluorocarbon rubber.

The embodiment shown in Figure 2 is similar to the embodiment of Figure 1, the same reference numerals being used for similar parts, but in this case the resilient layer is brought round the outer surface of the leg 17 of the outer shell member and extends radially inwardly to form a secondary sealing lip 21. The embodiment of Figure 3 is very similar to that of Figure 2 except that the secondary sealing lip 21 has a different shape.

The difference between the embodiment of Figure 4 and that of Figure 1 is that a secondary sealing lip 22 is provided by a second P.T.F.E. sealing member 26 which also has a radially extending portion 24 secured between the legs 17 and 19 of the shell members. Specifically the portion 24 is sandwiched between the portion 18 of the sealing member 14 and the washer 15.

The embodiments of Figures 1 to 4 have the resilient layer 11 provided with a ribbed external surface but these could equally well have a plain outside surface as shown in Figure 5. Figure 5 also differs from the previous embodiments in that the layer 11 is provided with a radially outwardly projecting flange 30 also in that the friction washer 15 is formed integraily with the layer 11 and its secondary lip 21.

1. A rotary seal comprising an outer shell member, an inner shell member, a P.T.F.E. sealing element having a radially extending portion secured between radially extending portions of the inner and outer shell members, and a layer of resilient material bonded to the outer surface of the outer shell member.

2. A rotary seal as claimed in claim 1, including a friction member also secured between the radially extending portions of the inner and outer shell members.

3. A rotary seal as claimed in claim 1 or claim 2, in which the layer of resilient material extends radially inwardly on the surface of the radially extending portion of the outer shell member.

4. A rotary seal as claimed in claim 3, in which the layer of resilient material is formed integrally with a sealing lip.

5. A rotary seal as claimed in claim 3 when dependent on claim 2, in which the friction member is formed integrally with the layer of resilient material.

6. A rotary seal as claimed in any of claims 1 to 3, including a second P.T.F.E. sealing element secured between the radially extending portions of the shell members.

7. A rotary seal substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Rotary shaft seal This invention is concerned with rotary seals, which incorporate a sealing element made of polytetrafluroethylene (hereinafter referred to as P.T.F.E.). Rotary seals incorporating P.T.F.E. sealing element are well known and are generaliy provided with a metal shell having an outside diameter that is either ground finished to a predetermined size or has a sealant applied thereto. These forms of finish are acceptable for those appiications which have housings, into which the seal is pressed, of substantial or robust construction. Problems occur when the seals are required to be fitted into thin wall housings, particularly those of aluminium or aluminium alloy or where the housing is split in two parts for assembly and dismantling purposes. The present invention is a rotary seal comprising an outer shell member, an inner shell member, a P.T.F.E. sealing element having a radially extending portion secured between radially extending portions of the inner and outer shell members, and a layer of resilient material bonded to the outer surface of the outer shell member. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, the five Figures of which each show a radial cross section of a rotary seal according to the present invention. The seal of Figure 1 has an outer annular shell member 12 of substantially L-shaped cross section and on the radial extending leg 17 thereof are mounted a friction member or washer 15, and a radially extending portion 18 of a P.T.F.E. sealing member 14. The washer 15 and the member 14 are secured in a position by an inner annular shell member 13 of L-shaped cross section whose radially extending leg 19 overliesthe portion 18 ofthe sealing member and is pressed towards the leg 17 of the outer shell member by the top of the radial leg of the outer member 12 which is peened over. The function of the friction washer 15 is simply to prevent the sealing element turning in the shell, and to prevent leakage through the internal parts of the seal. The sealing member 14 is in itself conventional and has a sealing lip 20 adapted to engage and seal against a rotary shaft passing through the seal. On the outer surface of the outer shell member 12 is provided a layer of resilient material 11 which is bonded to the member 12 and which can be compressed and thus absorb the misalignments which can occur with split housing, thus protecting the shell members against distortion. Typical suitable materials are the weli known rubbers and elastomers such as nitrile, polyacrylic, silicone orfluorocarbon rubber. The embodiment shown in Figure 2 is similar to the embodiment of Figure 1, the same reference numerals being used for similar parts, but in this case the resilient layer is brought round the outer surface of the leg 17 of the outer shell member and extends radially inwardly to form a secondary sealing lip 21. The embodiment of Figure 3 is very similar to that of Figure 2 except that the secondary sealing lip 21 has a different shape. The difference between the embodiment of Figure 4 and that of Figure 1 is that a secondary sealing lip 22 is provided by a second P.T.F.E. sealing member 26 which also has a radially extending portion 24 secured between the legs 17 and 19 of the shell members. Specifically the portion 24 is sandwiched between the portion 18 of the sealing member 14 and the washer 15. The embodiments of Figures 1 to 4 have the resilient layer 11 provided with a ribbed external surface but these could equally well have a plain outside surface as shown in Figure 5. Figure 5 also differs from the previous embodiments in that the layer 11 is provided with a radially outwardly projecting flange 30 also in that the friction washer 15 is formed integraily with the layer 11 and its secondary lip 21. CLAIMS