US 5,211,099 AGranted

Slave cylinder for a hydraulic actuating system of a motor vehicle friction clutch

AssigneeFichtel & Sachs AG

InventorsWolfgang Grosspietsch, Gottfried Mader, Herbert Voit, Karl Muller

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Abstract

A slave cylinder of the annular cylinder type is proposed, whereof the annular piston (45) able to slide axially between an outer cylinder wall (29) and an inner cylinder wall (33) is sealed by a grooved sealing ring (53) with respect to the pressure chamber (37). In order to be able to evacuate by means of a suction pump a hydraulic actuating system for a motor vehicle friction clutch, constructed using a slave cylinder of this type, before filling with hydraulic fluid, means are provided on the annular cylinder or in addition to the sealing lips (57) on the grooved sealing ring, which increase the sealing action of the sealing lips (57) when applying a vacuum to the hydraulic pressure chamber (37). The said means may be conical surfaces (61, 63) on the cylinder walls or a conical ring engaging in an annular groove (59) of the sealing ring (53). Additional sealing beads having a cross-sectional contour in the shape of a circular sector may be formed if necessary on the grooved sealing ring.

Claims21

Dependent claims

A slave cylinder for a hydraulic actuating system of a motor vehicle friction clutch, comprising:

an annular cylinder with an outer cylinder wall, an inner cylinder wall coaxial with the outer cylinder wall and an end wall hermetically connecting the cylinder walls at one end;
an annular piston arranged to slide axially between the outer cylinder wall and the inner cylinder wall;
a grooved sealing ring able to slide axially together with the annular piston and bearing by radially resilient sealing lips coaxial with an annular groove radially therebetween, both against the outer cylinder wall as well as against the inner cylinder wall, at the end of the annular piston facing the end wall, which piston together with the cylinder walls and the end wall encloses a hydraulic pressure chamber;
a pressure medium connection opening into the hydraulic pressure chamber;
and
means which are at least one of provided on the annular cylinder and in addition to the sealing lips on the grooved sealing ring, said means increasing the sealing action of the sealing lips one of in a predetermined position of the annular piston relative to the annular cylinder and when applying a vacuum to the hydraulic pressure chamber,
wherein in the region of one of the end positions of the annular piston, the annular cylinder is provided with annular bearing surfaces, against which the sealing lips bear in the end position of the annular piston and which increase the radial pressure by which the sealing lips bear against the cylinder walls, and further
wherein the annular bearing surfaces are constructed as conical surfaces.

5 more elements

A slave cylinder for a hydraulic actuating system of a motor vehicle friction clutch, comprising:

an annular cylinder with an outer cylinder wall, an inner cylinder wall, coaxial with the outer cylinder wall, and an end wall tightly connecting the cylinder walls at one end;
an annular piston arranged so as to be axially displaceable between said outer cylinder wall and said inner cylinder wall;
a grooved sealing ring which is arranged at the end of said annular piston facing said end wall of said annular cylinder, which is displaceable together with said annular piston and, together with the cylinder walls and said end wall of said annular cylinder encloses a hydraulic pressure chamber, wherein said grooved sealing ring further comprises:
an annular base body;
radially resilient sealing lips, which project away from said base body toward said end wall and encloses an annular groove between them;
a first sealing lip contacting said outer cylinder wall;
a second sealing lip contacting said inner cylinder wall;
sealing beads for increasing the sealing action when a vacuum is applied to said hydraulic pressure chamber, which sealing beads project radially from said base body and are arranged on a side of said sealing lips remote of said end wall of said annular cylinder,
wherein a first sealing bead projects from an outer circumference of said base body toward said outer cylinder wall and a second sealing bead projects from an inner circumference of said base body toward said inner cylinder wall, and further wherein, in an absence of said grooved sealing ring, installed in said annular cylinder, diameters of said first and said second beads have a smaller radial overlap, with a diameter of said cylinder wall intended for contact, than a diameter of said sealing lip intended for contact at a same cylinder wall, and further wherein annular gaps exist axially between said sealing beads and said sealing lips and radially between said base body and the cylinder walls;
and
a pressure medium connection opening into said hydraulic pressure chamber.

8 more elements

Dependencies are inferred from the claim text.