Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
1998-04-07
2001-04-03
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S566000
Reexamination Certificate
active
06209882
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a lip seal for sealing cylindrical surfaces, especially those of input and output hydraulic cylinders in motor vehicles, axially fixed in a cylindrical part of a cylinder housing with a first sealing lip directed against the cylinder housing and a second sealing lip directed against a cylindrical surface of a piston which is axially movably within the cylinder housing.
2. Description of the Related Art
German reference DE 195 23 011 A1 discloses a hydraulic clutch release device for a friction clutch having a housing. A telescopic piston including a primary piston and a secondary piston is arranged in a central recess, of the housing for the purpose of attaining reduced structural length. The primary piston has a lip seal with an inwardly directed sealing lip and an outwardly directed sealing lip on its ring-shaped front face. The lip seal is mounted and held in its position with the primary piston in an annular groove in the front face of the primary piston. This fixing of the lip seal is required to neutralize tilting moments that occur as the result of the translatory movements in different directions of the outer cylindrical surface relative to the inner cylindrical surface.
SUMMARY OF THE INVENTION
The lip seal proposed by the present invention has very small radial dimensions, relative to the ratio of its inner diameter to its outer diameter. The thin dimensions make it impossible to fix the lip seal in its position by a ring groove or to rule out tilting movements of the lip seal which occur due to the movement of an inner piston relative to the housing, in which the lip seal is arranged. Furthermore, lip seals without a fitting are instable because of the constantly changing pressure conditions they are subjected to, and react with tilting movements around a ring axis that runs annularly through a center of the lip seal.
The object of the invention is therefore to prevent tilting movement around an central axis that runs annularly though a center of a non-fitted lip seal with at least one sealing lip during translatory movements and changing pressure conditions.
The attainment of this object includes a lip seal axially fixed in a cylindrical part of a cylinder housing with a first sealing lip directed against the cylinder housing and a second sealing lip directed against a cylindrical surface of a piston which is axially movably within the cylinder housing. The lip seal also includes a supporting head which forms a third contact seal against the cylindrical part of the housing.
The various features of novelty which characterize the invention are pointed out with particularity in to claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 3228705 (1966-01-01), Underwood
patent: 3940155 (1976-02-01), Baumle
patent: 4262915 (1981-04-01), Williams
patent: 4371177 (1983-02-01), Bähr
patent: 4858516 (1989-08-01), Klein
patent: 5431415 (1995-07-01), Millonig
patent: 195 23 011 A1 (1997-01-01), None
patent: 0 014 905 (1980-02-01), None
patent: 810625 (1959-03-01), None
patent: 811485 (1959-04-01), None
patent: 974751 (1964-11-01), None
patent: 2 085 983 (1982-05-01), None
patent: WO89/03954 (1989-05-01), None
Cohen & Pontani, Lieberman & Pavane
Knight Anthony
Mannesmann Sachs AG
Patel Vishal
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