GB2058960A

GB2058960A - Shaft seal arrangement

Info

Publication number: GB2058960A
Application number: GB7932273A
Authority: GB
Original assignee: Dresser Europe SPRL
Current assignee: Dresser Europe SPRL
Priority date: 1979-09-18
Filing date: 1979-09-18
Publication date: 1981-04-15
Also published as: GB2058960B

Abstract

A seal for a rotatable shaft 2 which passes through a housing wall 1 has a fist seal 10 resiliently urged against the shaft, a cup- shaped dust cover 12 fixed on the shaft and a second seal 14 urged against the skirt 13 of the dust- cover, the seals being secured to the exterior of the housing wall. The seals are integral with each other and comprise a flexible annular member bonded to a metal backing plate 8. <IMAGE>

Description

SPECIFICATION Shaft seal arrangement The invention relates to a seal arrangement for sealing a rotatable shaft with respect to a housing wall through which the shaft passes.

Particular application for the invention is found in sealing the drive shaft for a pump unit in a liquid fuel dispensing pump for garage forecourt use. The pump drive shaft is sealed in order to prevent loss of fuel from the pump via the shaft bearing and it is found that in this particular application the seal wears remarkably quickly and regular maintenance is required to prevent undue leakage. It is felt that this is due in large part to the situation of the pump which, being near the ground is subjected to large amounts of dust and dirt which enter the seal and wear the seal and the shaft.

An improvement could be effected by providing one or more additional seals on the shaft to seal the first seal against dust. However, such an arrangement would require an additional length of shaft protruding from the housing for sealing purposes and while a longer shaft could be provided in a freshly designed pump unit, such an additional sealing arrangement is not suitable for existing units. The present invention seeks to provide an improved sealing arrangement which overcomes this problem.

According to the invention there is provided a shaft seal arrangement for sealing a rotatable shaft with respect to a housing wall through which the shaft passes, the arrangement comprising a first seal of flexible material fixed to the exterior of the housing wall and resiliently urged against the surface of the shaft; a cup-shaped dust cover fixed to rotate with the shaft and having a skirt disposed to embrace the first seal; and a second seal of flexible material fixed to the exterior of the housing wall and resiliently urged against the skirt. With this arrangement the second seal is provided as a dust seal to protect the first seal, the first and second seals being radially spaced rather than axially spaced. In this way no additional axial length of the shaft is required and the dust cover and second seal may be fixed to existing pumps.

Preferably the second seal seals against the inside of the skirt. Preferably the first and second seals are integral with each other, being constituted by a flexible annular member which is fixed to the housing wall around the shaft.

Preferably the second seal is constituted by a lip of the annular member which is curled against the interior of the skirt when the dust cover is placed in position.

The first seal may be constituted by a shaped interior lip of the annular member which is laid against the surface of the shaft and held by a spring clip. The annular member may be of natural or artificial rubber, preferably bonded to a metal backing plate.

The invention will further be described with reference to the accompanying drawing, the sole figure of which is a cross-sectional side view of a fuel pump embodying the invention.

Referring to the drawing, the pump is for pumping liquid fuel to be dispensed. The pump has a housing with a wall 1 through which passes the drive shaft 2 of the pump.

The shaft is carried by a plain metal bearing 3. Drive is effected by a pulley 4 which receives a belt (not shown) and which is keyed to the shaft by key 5. A nut 6 is threaded onto the shaft to hold the pulley in place.

The seal of the invention comprises a rubber annular member 7 which is bonded to a metal backing plate 8. The plate 8 is screwed by three screws, one of which is shown at 9, to the housing 1. A first seal is constituted by a turned-over lip 10 at the interior of the annular member, the lip being urged against the surface of the shaft by a spring clip 11.

A cup-shaped dust cover 1 2 is fitted to the shaft and is clamped in place by the pulley so that the dust cover rotates with the shaft. The cover has a skirt 1 3 which embraces the annular member 7 and a second seal is constituted by a lip 14 of the annular member which is curled over to seal against the inside of the skirt when the cover is placed in position.

The second, outer, seal provides a seal against the ingress of dust so that the first seal is protected thereby.

1. A shaft seal arrangement for sealing a rotatable shaft with respect to a housing wall through which the shaft passes, the arrangement comprising a first seal of flexible material fixed to the exterior of the housing wall and resiliently urged against the surface of the shaft; a cup-shaped dust cover fixed to rotate with the shaft and having a skirt disposed to embrace the first seal; and a second seal of flexible material fixed to the exterior of the housing wall and resiliently urged against the skirt.

2. A shaft seal arrangement as claimed in Claim 1 wherein the second seal seals against the inside of the skirt.

3. A shaft seal arrangement as claimed in either of the preceding claims wherein the first and second seals are integral with each other, being constituted by a flexible annular member which is fixed to the housing wall around the shaft.

4. A shaft seal arrangement as claimed in Claim 3 wherein the second seal is constituted by a lip of the annular member which is curled against the interior of the skirt when the dust cover is placed in position.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Shaft seal arrangement The invention relates to a seal arrangement for sealing a rotatable shaft with respect to a housing wall through which the shaft passes. Particular application for the invention is found in sealing the drive shaft for a pump unit in a liquid fuel dispensing pump for garage forecourt use. The pump drive shaft is sealed in order to prevent loss of fuel from the pump via the shaft bearing and it is found that in this particular application the seal wears remarkably quickly and regular maintenance is required to prevent undue leakage. It is felt that this is due in large part to the situation of the pump which, being near the ground is subjected to large amounts of dust and dirt which enter the seal and wear the seal and the shaft. An improvement could be effected by providing one or more additional seals on the shaft to seal the first seal against dust. However, such an arrangement would require an additional length of shaft protruding from the housing for sealing purposes and while a longer shaft could be provided in a freshly designed pump unit, such an additional sealing arrangement is not suitable for existing units. The present invention seeks to provide an improved sealing arrangement which overcomes this problem. According to the invention there is provided a shaft seal arrangement for sealing a rotatable shaft with respect to a housing wall through which the shaft passes, the arrangement comprising a first seal of flexible material fixed to the exterior of the housing wall and resiliently urged against the surface of the shaft; a cup-shaped dust cover fixed to rotate with the shaft and having a skirt disposed to embrace the first seal; and a second seal of flexible material fixed to the exterior of the housing wall and resiliently urged against the skirt. With this arrangement the second seal is provided as a dust seal to protect the first seal, the first and second seals being radially spaced rather than axially spaced. In this way no additional axial length of the shaft is required and the dust cover and second seal may be fixed to existing pumps. Preferably the second seal seals against the inside of the skirt. Preferably the first and second seals are integral with each other, being constituted by a flexible annular member which is fixed to the housing wall around the shaft. Preferably the second seal is constituted by a lip of the annular member which is curled against the interior of the skirt when the dust cover is placed in position. The first seal may be constituted by a shaped interior lip of the annular member which is laid against the surface of the shaft and held by a spring clip. The annular member may be of natural or artificial rubber, preferably bonded to a metal backing plate. The invention will further be described with reference to the accompanying drawing, the sole figure of which is a cross-sectional side view of a fuel pump embodying the invention. Referring to the drawing, the pump is for pumping liquid fuel to be dispensed. The pump has a housing with a wall 1 through which passes the drive shaft 2 of the pump. The shaft is carried by a plain metal bearing 3. Drive is effected by a pulley 4 which receives a belt (not shown) and which is keyed to the shaft by key 5. A nut 6 is threaded onto the shaft to hold the pulley in place. The seal of the invention comprises a rubber annular member 7 which is bonded to a metal backing plate 8. The plate 8 is screwed by three screws, one of which is shown at 9, to the housing 1. A first seal is constituted by a turned-over lip 10 at the interior of the annular member, the lip being urged against the surface of the shaft by a spring clip 11. A cup-shaped dust cover 1 2 is fitted to the shaft and is clamped in place by the pulley so that the dust cover rotates with the shaft. The cover has a skirt 1 3 which embraces the annular member 7 and a second seal is constituted by a lip 14 of the annular member which is curled over to seal against the inside of the skirt when the cover is placed in position. The second, outer, seal provides a seal against the ingress of dust so that the first seal is protected thereby. CLAIMS

5. A shaft seal arrangement as claimed in Claim 3 or Claim 4 when the first seal is constituted by a shaped interior lip of the annular member which is laid against the surface of the shaft and held by a spring clip.

6. A shaft seal arrangement substantially as hereinbefore described with reference to the accompanying drawings.