Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1989-12-08
1991-10-15
Cuchlinski, Jr., William A.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277180, 277188R, 2771895, B16F 1522
Patent
active
050568019
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to seals for sealing a shaft to a sheet of material through which the shaft extends, and more particularly to a seal for sealing a shaft to a sheet of glass.
In modern vehicle and particularly car design where ever larger areas of glass are being used it is becoming increasingly necessary to mount a screen wiper motor beneath a glass screen wiped by the wiper. This necessitates that a shaft associated with a wiper arm should extend through the screen and be sealed thereto to prevent ingress of water into the vehicle.
DESCRIPTION OF THE RELATED ART
The prior art discloses a sealing method wherein a standard rubber grommet is forced into position in the hole with each flange thereof sprung against an opposing face of the glass sheet by the resilience of the rubber. This method suffers from the drawbacks that fitting of the grommet to the sheet of glass can be awkward and does not lend itself to automation, and secondly that sealing of the grommet to the glass is often difficult to achieve owing to the compromise necessary in selecting a consistency of rubber soft enough to provide a seal and hard enough to provide adequate support for sealing surfaces of the grommet.
SUMMARY OF THE INVENTION
It is an object of the invention to overcome the difficulties associated with the prior art.
According to the invention there is provided a seal for sealing a shaft to a sheet of material, the seal having a hollow body to extend through an aperture in the sheet of material, an outwardly extending flange on one end of the body, at least one first annular sealing element extending radially inwardly of the body for co operation with the shaft to provide a seal therebetween, a second annular sealing element interposed between the flange and a first face of the sheet of material to seal the flange to the sheet, and retaining means on the other end of the body to retain the body in the aperture and bias the flange towards the first face of the sheet of material, wherein the body and the flange are of relatively hard material and the first and second annular sealing elements are of relatively soft material.
Because the body and flange of the seal are of relatively hard material they provide a firm and accurate support for the relatively soft sealing elements. The sealing elements may thus be accurately located with respect to the shaft and sheet of material respectively to encourage sealing and to distribute stresses between the shaft and material in a controlled manner to avoid the possibility of the material cracking or suffering other permanent damage. Furthermore, the seal does not need to stand proud of the first face of the sheet by as much as does a rubber grommet because the relatively hard material used is better able to provide support for the sealing elements than is the rubber of the grommet.
The retaining means may comprise a plurality of resilient legs having outwardly extending feet on free ends thereof, the legs extending axially of the body from the other end thereof, the feet being biased by the legs into engagement with a second face of the sheet.
Preferably the retaining means comprises a plurality of resilient legs having outwardly extending feet on free ends thereof, the legs extending axially of the body from the other end thereof, and a washer positioned around the legs and secured against the second face of the sheet by the feet.
Most preferably the washer has a layer of relatively soft elastomeric material and a layer of relatively hard material, the layer of elastomeric material being arranged to bear against the sheet.
The presence of the washer, spreading retaining forces over the second face of the sheet, serves evenly to distribute said forces into the sheet, thereby minimising the possibility of damage to the sheet by the seal. Furthermore, the elastomeric layer on the washer serves to insulate the sheet from shock loads transmitted through the seal from the shaft whilst at the same time taking up tolerances between the seal and the
REFERENCES:
patent: 3519279 (1970-07-01), Wagner
patent: 3548079 (1970-12-01), Jones et al.
patent: 3887960 (1975-06-01), Sherman
patent: 4041241 (1977-08-01), Olmstead et al.
patent: 4656689 (1987-04-01), Dennis
patent: 4822079 (1989-04-01), Schulte
Cuchlinski Jr. William A.
Folker James K.
Rover Group Limited
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