# US 5,704,462 A · Cylinder for hydraulically operated clutches and brakes and hydraulically operated clutch assemblies for motor vehicles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,704,462 A - Document ID: US5704462A - Status: Granted - Kind: A - Application number: 08/561,288 - Filed: 1995-11-21 - Granted: 1998-01-06 - Earliest claimed: 1994-11-23 - Assignees: Fichtel & Sachs AG - Inventors: Wolfgang Grosspietsch; Alfred Eusemann - Web page: https://patentgrep.com/patent/US5704462A ## CPC - F16D 25/08: with fluid-actuated member not rotating with a clutching member (F16D25/02 takes precedence {F16D25/048 takes precedence}) - B60T 11/16: Master control, e.g. master cylinders (master cylinders associated with vacuum boosters B60T13/565) - F16D 25/12: Details not specific to one of the before-mentioned types - F16D 25/088: {the line of action of the fluid-actuated members being distinctly separate from the axis of rotation} - F16D 2025/081: {Hydraulic devices that initiate movement of pistons in secondary cylinders for actuating clutches, i.e. primary cylinders} - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES ## Abstract A cylinder for hydraulic systems, in particular for motor vehicles, includes a housing with an axial boring, in which a piston fastened to a piston rod is displaced axially in a guided manner, and one end surface of which is pressurized with hydraulic fluid, and which is guided in a sealed manner with respect to the housing. The cylinder is provided with connections for at least one pressure line, a connection to a fluid chamber and for fastening, and at least one lip seal, which lip seal is located in the housing to seal the housing with respect to the exterior surface of the piston. The piston and/or the piston rod, between the hydraulic fluid and the terminal area of the piston rod farther from the piston, is provided with a device for damping pressure surges from the hydraulic fluid. These cylinders are preferably used in hydraulically operated clutch assemblies for motor vehicles and alternatively for braking systems in motor vehicles. ## Claims ### Claim 1 A hydraulically operated clutch assembly for a motor vehicle, said clutch assembly comprising: a flywheel defining an axis of rotation and an axial direction parallel to the axis of rotation; a clutch disc; a pressure plate for applying an axially directed force to said clutch disc, with respect to said axis of rotation of said flywheel, to engage said clutch disc with said flywheel; said clutch disc being disposed between said flywheel and said pressure plate; said clutch disc comprising friction lining means for contacting said pressure plate and said flywheel during engagement of said clutch disc with said flywheel; means for hydraulically actuating said clutch disc; said hydraulic actuating means comprising: a cylinder, said cylinder having a first end and a second end and defining a chamber therein, at least a portion of said chamber comprising hydraulic fluid therein; a piston rod extending through said first end of said cylinder and into said chamber; a piston fastened to said piston rod; said piston being axially displaced in a guided manner within said cylinder; means for providing hydraulic fluid into and out of said chamber; first means for connecting said cylinder with said means for providing hydraulic fluid; second means for connecting said cylinder to a portion of said motor vehicle; said piston comprising a hollow cylindrical-shaped outer part; said outer part being closed at one end; said piston comprises an inner part; said inner part comprising an end surface; and at least one of: said end surface of the inner part, and said closed end of said outer part comprising at least one of: raised areas; and depressions; and said raised areas comprising elastically deformable material. ### Claim 2 A hydraulically operated clutch assembly for a motor vehicle, said clutch assembly comprising: a flywheel defining an axis of rotation and an axial direction parallel to the axis of rotation; a clutch disc; a pressure plate for applying an axially directed force to said clutch disc, with respect to said axis of rotation of said flywheel, to engage said clutch disc with said flywheel; said clutch disc being disposed between said flywheel and said pressure plate; said clutch disc comprising friction lining means for contacting said pressure plate and said flywheel during engagement of said clutch disc with said flywheel; a mechanism for hydraulically actuating said clutch disc; said hydraulic actuating mechanism comprising: a cylinder, said cylinder having a first end and a second end and defining a chamber therein, at least a portion of said chamber comprising hydraulic fluid therein; a piston rod extending through said first end of said cylinder and into said chamber; a piston fastened to said piston rod; said piston being axially displaced in a guided manner within said cylinder; means for providing hydraulic fluid into and out of said chamber; first means for connecting said cylinder with said means for providing hydraulic fluid; second means for connecting said cylinder to a portion of said motor vehicle; a ring-shaped elastic suspension being disposed between the piston rod and the piston; said piston comprising a hollow cylindrical-shaped piston; said piston being closed at one end; said cylindrical-shaped piston having a first end portion; said ring-shaped elastic suspension being disposed in said first end portion; said ring-shaped elastic suspension comprising recesses; an end portion of said piston rod comprising an extension; and means for fastening said extension of said piston rod to said recesses of said ring-shaped elastic suspension. ### Claim 3 A hydraulically operated clutch assembly for a motor vehicle, said clutch assembly comprising: a flywheel defining an axis of rotation and an axial direction parallel to the axis of rotation; a clutch disc; a pressure plate for applying an axially directed force to said clutch disc, with respect to said axis of rotation of said flywheel, to engage said clutch disc with said flywheel; said clutch disc being disposed between said flywheel and said pressure plate; said clutch disc comprising friction lining means for contacting said pressure plate and said flywheel during engagement of said clutch disc with said flywheel; a mechanism to hydraulically actuate said clutch disc; said hydraulic actuating mechanism comprising: a cylinder, said cylinder having a first end and a second end and defining a chamber therein, at least a portion of said chamber comprising hydraulic fluid therein; piston rod means extending through said first end of said cylinder and into said chamber; a piston fastened to said piston rod means; said piston being axially displaced in a guided manner within said cylinder; means for providing hydraulic fluid into and out of said chamber; first means for connecting said cylinder with said means for providing hydraulic fluid; second means for connecting said cylinder to a portion of said motor vehicle; means for damping pressure surges and vibrations; and said damping means being disposed on at least one of: said piston and said piston rod means; said piston has an inner portion and an outer portion; at least one lip seal being disposed in said housing to seal said housing with respect to said outer portion of said piston; said at least one lip seal being disposed in an axial hole with no undercutting of the housing; and said at least one lip seal being axially supported by means of a fixing element locked to the housing; said fixing element carrying a wiper ring which is engaged with the piston rod means. ### Claim 4 In a motor vehicle, a cylinder for hydraulic systems for actuating at least one of: a clutch and a braking system; said cylinder comprising piston rod means; the cylinder further comprising a piston fastened to said piston rod means; the piston being axially displaced in a guided manner within the cylinder; said cylinder having a first end and a second end and defining a chamber therein, at least a portion of said chamber comprising hydraulic fluid therein; means for providing hydraulic fluid into and out of said chamber; first means for connecting said cylinder with said means for providing hydraulic fluid; second means for connecting said cylinder to a portion of said motor vehicle; said piston comprising a hollow cylindrical-shaped outer part; said outer part being closed at one end; said piston comprises an inner part; said inner part comprises an end surface; and at least one of: said end surface of the inner part, and said closed end of the outer part comprising at least one of: raised areas; and depressions; said raised areas comprising elastically deformable material; said piston having a first end; said first end comprising a ring-shaped elastic suspension; said ring-shaped elastic suspension comprising recesses; an end portion of said piston rod comprising an extension; means for fastening said extension of said piston rod to said recesses of said ring-shaped elastic suspension; said piston having an inner portion and an outer portion; at least one lip seal being disposed in said housing to seal said housing with respect to said outer portion of said piston; said at least one lip seal being disposed in an axial hole with no undercutting of the housing; said at least one lip seal being axially supported by means of a fixing element locked to the housing; said fixing element carrying a wiper ring which is engaged with the piston rod means; the pressure connection being located at some distance from the bottom of the cylinder; and the pressure connection being connected to the cylinder by means of a groove which runs radially between the piston and the interior of the cylinder, whereby the cross section of the groove, together with the distance between the pressure connection and the bottom of the cylinder, achieves a defined hydraulic damping.