Hydraulic booster

Claim 2

A hydraulic brake booster assembly comprising: a power piston movable in a cylinder bore with a power chamber at one end thereof; an open center control valve including a hydraulic reaction valve seat member and a movable resiliently mounted valve member cooperating with said valve seat member to define the control valve, said control valve normally having hydraulic fluid flowing therethrough; said power piston providing mounting means receiving said hydraulic reaction valve member for reciprocal movement relative to said power piston, said hydraulic reaction valve seat member being urged in the control valve opening direction by yieldable means acting between said power piston and said hydraulic reaction valve seat member, and being urged in the control valve closing direction by fluid pressure in said power chamber, whereby pressure increase in said power chamber causes said power piston to move in the cylinder bore a greater distance than the movement of said valve member in the same direction which caused the pressure increase in said power chamber by restricting fluid flow through said control valve; an input member providing mounting means receiving said resiliently mounted valve member, and movable to control the restrictive action of said control valve to control the power pressure in said power chamber and thereby control the power output of the booster assembly, said input member having accumulator charge and release passage means therein and valve means controlling the fluid communication of said passage means with said power chamber, said valve means opening to increase fluid pressure in said accumulator charge and release passage means at a predetermined pressure differential between said passage means and said power chamber so as to pressure charge an accumulator connected to said passage means, said valve means being opened by the action of movement of said valve member on said input member against the resilient mounting thereof to release fluid pressure in said passage means into said power chamber, said valve member having contacted said valve seat member and closed said control valve.

Claim 3

A hydraulic booster assembly having an input member and an output member and a power piston reciprocably mounted in a cylinder bore with a power chamber at one end thereof; an open center valve assembly for controlling the pressure in the power chamber actuating the power piston, said valve assembly including a first valve member reciprocably mounted on said power piston and urged in a relative valve opening direction by a spring and having an effective differential area responsive to actuating pressure in said power chamber urging the first valve member toward a relative valve closing direction, and a second valve member reciprocably mounted for limited axial movement on said input member and positioned in valving relation with said first valve member and urged against a stop on said input member in a relative valve closing direction by another spring and also by actuating pressure in the power chamber; a balance piston reciprocably received in cylinder bore formed in said power piston and secured to said input member and having one side exposed to atmospheric pressure and the other side exposed to hydraulic fluid pressure downstream of said open center valve assembly with the differential pressure acting thereon to balance said input member and said second valve member against pressure changes occurring in the hydraulic actuating fluid downstream oF said valve members; and accumulator charge and release valve means responsive to hydraulic fluid pressure upstream of said valve members so as to open when that pressure exceeds the pressure charge of an accumulator connected therewith, said valve means being positioned in relation to said second valve member so that movement of said second valve member, in opposition to the spring acting thereon and in response to closure of said valve members followed by further brake apply movement of said input member, opens said valve means to admit accumulator pressure upstream of said valve members to actuate said power piston by introducing accumulator pressure into said power chamber.

Claim 4

A hydraulic booster assembly having an input member and an output member and a power piston reciprocably mounted in a cylinder bore with a power chamber at one end thereof; an open center valve assembly for controlling the pressure in the power chamber actuating the power piston, said valve assembly including a first valve member reciprocably mounted on said power piston and urged in a relative valve opening direction by a spring and having an effective differential area responsive to actuating pressure in said power chamber urging the first valve member toward a relative valve closing direction, and a second valve member reciprocably mounted for limited axial movement on said input member and positioned in valving relation with said first valve member and urged against a stop on said input member in a relative valve closing direction by another spring and also by actuating pressure in the power chamber; a balance piston reciprocably received in cylinder bore formed in said power piston and secured to said input member and having one side exposed to atmospheric pressure and the other side exposed to hydraulic fluid pressure downstream of said open center valve assembly with the differential pressure acting thereon to balance said input member and said second valve member against pressure changes occurring in the hydraulic actuating fluid downstream oF said valve members; and accumulator charge and release valve means responsive to hydraulic fluid pressure upstream of said valve members so as to open when that pressure exceeds the pressure charge of an accumulator connected therewith, said valve means being positioned in relation to said second valve member so that movement of said second valve member, in opposition to the spring acting thereon and in response to closure of said valve members followed by further brake apply movement of said input member, opens said valve means to admit accumulator pressure upstream of said valve members to actuate said power piston by introducing accumulator pressure into said power chamber.

Claim 5

A hydraulic brake booster comprising: a housing having a bore formed therein, a fluid inlet port communicating with one end of said bore, a fluid outlet port communicating with the other end of said bore, and closures for said bore ends; a power piston assembly reciprocably received in said bore so as to define therewith a power chamber at said one bore end and an exhaust chamber at said other bore end, said power piston having a reduced diameter forward end sealingly and movably extending through an aperture formed in the one of said closures closing said other bore end, a reduced diameter rear end in said power chamber, and a stepped bore with first and second power piston bore sections respectively formed in said forward and rear piston ends and separated by a shoulder, said second power piston bore section having a larger diameter than said first power piston bore section and forming a part of said power chamber; an annular stepped reaction piston reciprocably and sealingly received in said first and second power piston bore sections, a spring, said reaction piston having a shoulde urged toward abutting relation with said power piston shoulder by said spring, an annular valve seat formed on said reaction piston with an effective diameter greater than said first power piston bore section by an amount establishing a reaction area subject to power chamber pressure and acting in opposition to said spring; an input member assembly including a push rod extending through a bore formed in the other of said closures and having a reduced diameter forward end positioned in said power chamber, a balance piston reciprocably and sealingly received in said first power piston bore section forward of said reaction piston and having a rod extending freely through said reaction piston and secured to said push rod reduced diameter forward end and having a stop thereon in axially spaced relation to said push rod reduced diameter forward end, an annular control valve having an external valve face and a rearwardly opening recess and slidably mounted on said balance piston rod axially intermediate said stop and said push rod reduced diameter forward end with said push rod reduced diameter forward end being sealingly and reciprocably received in said rearwardly opening recess, said valve face being in valving relation with said valve seat, the forward end of said rearwardly opening recess cooperating with said balance piston rod and said push rod reduced diameter forward end to define a chamber having a spring therein urging said control valve against said stop; and an output push rod connected in force transmitting relation with said power piston forward end and adapted to connect with a master cylinder assembly in operative relation; said piston forward end having a first port therein connecting the end of said first piston bore section on the opposite side of said balance piston from said reaction piston with atmospheric pressure and a second port therein connecting the portion of said first power piston bore section intermediate said balance piston and said reaction piston with said exhaust chamber, a meterable flow path being established from said fluid inlet port into said power chamber, through the metering valve formed by said annular control valve and said valve seat, through saId annular reaction piston into said portion of said first power piston bore section intermediate said balance piston and said reaction piston, through said second port into said exhaust chamber, and out of said exhaust chamber through said fluid outlet port.

Claim 6

A hydraulic brake booster comprising: a housing having a bore formed therein, a fluid inlet port communicating with one end of said bore, a fluid outlet port communicating with the other end of said bore, and closures for said bore ends; a power piston assembly reciprocably received in said bore so as to define therewith a power chamber at said one bore end and an exhaust chamber at said other bore end, said power piston having a reduced diameter forward end sealingly and movably extending through an aperture formed in the one of said closures closing said other bore end, a reduced diameter rear end in said power chamber, and a stepped bore with first and second power piston bore sections respectively formed in said forward and rear piston ends and separated by a shoulder, said second power piston bore section having a larger diameter than said first power piston bore section and forming a part of said power chamber; an annular stepped reaction piston reciprocably and sealingly received in said first and second power piston bore sections, a spring, said reaction piston having a shoulde urged toward abutting relation with said power piston shoulder by said spring, an annular valve seat formed on said reaction piston with an effective diameter greater than said first power piston bore section by an amount establishing a reaction area subject to power chamber pressure and acting in opposition to said spring; an input member assembly including a push rod extending through a bore formed in the other of said closures and having a reduced diameter forward end positioned in said power chamber, a balance piston reciprocably and sealingly received in said first power piston bore section forward of said reaction piston and having a rod extending freely through said reaction piston and secured to said push rod reduced diameter forward end and having a stop thereon in axially spaced relation to said push rod reduced diameter forward end, an annular control valve having an external valve face and a rearwardly opening recess and slidably mounted on said balance piston rod axially intermediate said stop and said push rod reduced diameter forward end with said push rod reduced diameter forward end being sealingly and reciprocably received in said rearwardly opening recess, said valve face being in valving relation with said valve seat, the forward end of said rearwardly opening recess cooperating with said balance piston rod and said push rod reduced diameter forward end to define a chamber having a spring therein urging said control valve against said stop; and an output push rod connected in force transmitting relation with said power piston forward end and adapted to connect with a master cylinder assembly in operative relation; said piston forward end having a first port therein connecting the end of said first piston bore section on the opposite side of said balance piston from said reaction piston with atmospheric pressure and a second port therein connecting the portion of said first power piston bore section intermediate said balance piston and said reaction piston with said exhaust chamber, a meterable flow path being established from said fluid inlet port into said power chamber, through the metering valve formed by said annular control valve and said valve seat, through saId annular reaction piston into said portion of said first power piston bore section intermediate said balance piston and said reaction piston, through said second port into said exhaust chamber, and out of said exhaust chamber through said fluid outlet port.