Slip control system master cylinder with piston sleeve

Claim 1

An actuating device for use in a master cylinder of the type including at least one piston means positionable in response to movement of a brake pedal for pressurizing hydraulic brake fluid in a hydraulic brake system having slip control, including means for supplying auxiliary pressurized hydraulic brake fluid into said master cylinder for replenishing said brake fluid in said brake system and for resetting the position of said piston means during operation of said slip control system comprising: a housing defining a portion of said master cylinder including a bore therein closed on one end and open at a second end; a generally tubular positioning sleeve sealingly, slidably mounted within said bore defining at a first annular pressure chamber between said positioning sleeve and said housing adapted to be hydraulically connected to at least one wheel brake of said brake system; a first piston part sealingly, slidably mounted in said tubular positioning sleeve proximate said open end and including means providing for operatively connecting said first piston part to said brake pedal for movement in an actuating direction in response to movement of said brake pedal; a generally cylindrical second piston part extending coaxially, partially into said positioning sleeve, said second piston part being sealingly supported at one end in said positioning sleeve and sealingly, slidably supported in a reduced diameter section of said bore, said second piston part supported against said closed end by a compression spring interposed between said closed end and said second piston part, said second piston part, an end of said positioning sleeve and said housing defining said auxiliary pressure chamber and said second piston part and said reduced diameter section of said bore defining a first working chamber having a variable volume adapted to be connected to at least a second wheel brake of said brake system; said auxiliary pressure chamber adapted to receive said auxiliary pressurized fluid, said positioning sleeve, said piston part and said first piston part defining a second working chamber having a variable volume and being in flow communication with said first annular chamber; means interconnecting said positioning sleeve to said first piston part at a predetermined position of said first piston part for movement therewith in the actuating direction; and one-way valve means associated with said positioning sleeve interconnecting said auxiliary pressure chamber to said second working chamber providing for flow of said auxiliary fluid into said second working chamber.