Vehicle power brake system with master booster and slave booster

Claim 2

A brake system in a vehicle having first and second brake actuating circuits for actuating first and second brake sets, said system comprising: a first differential pressure operated booster having first and second operating pressures; a first master cylinder actuatable by said first booster and having first and second brake actuating pressure outputs respectively connected to said first and second brake actuating circuits; a second differential pressure operated booster operatively connected with said first booster to receive said first and second operating pressures therefrom and having means acting only upon the establishment of operating pressures of a predetermined differential in said first booster to permit delivery of said differential operating pressures from said first booster to said second booster to operate said second booster; a second master cylinder actuatable by the operation of said second booster and having normally open valve means in said second brake actuating circuit fluidly intermediate said first master cylinder second brake actuating pressure output and the second brake set; said normally open valve means permitting brake actuating pressure to pass through said second master cylinder from said first master cylinder to the second brake set while open, and arranged to be closed by initial operation of said second booster, said second master cylinder being actuatable by operation of said second booster when said valve means is closed to pressurize the portions of said second brake actuating circuit from said second master cylinder to the second brake set in accordance with operation of said second booster.

Claim 3

A brake system in a vehicle having first and second brake actuating circuits for actuating first and second brake sets, said system comprising: a first differential pressure operated booster having first and second operating pressures; a first master cylinder actuatable by said first booster and having first and second brake actuating pressure outputs respectively connected to said first and second brake actuating circuits; a second differential pressure operated booster operatively connected with said first booster to receive said first and second operating pressures therefrom and having means acting only upon the establishment of operating pressures of a predetermined differential in said first booster to permit delivery of said differential operating pressures from said first booster to said second booster to operate said second booster; a second master cylinder actuatable by the operation of said second booster and having normally open valve means in said second brake actuating circuit fluidly intermediate said first master cylinder second brake actuating pressure output and the second brake set; said normally open valve means permitting brake actuating pressure to pass through said second master cylinder from said first master cylinder to the second brake set while open, and arranged to be closed by initial operation of said second booster, said second master cylinder being actuatable by operation of said second booster when said valve means is closed to pressurize the portions of said second brake actuating circuit from said second master cylinder to the second brake set in accordance with operation of said second booster; said second master cylinder having actuating pressure generating piston means therein actuatable by the force of operation of said second booster, said piston means having an effective area responsive to pressure from said first master cylinder second brake actuating pressure output when said valve means is closed to provide another actuating force on said piston means in addition to the actuating force of operation of said second booster.

Claim 4

A brake system in a vehicle having first and second brake actuating circuits for actuating first and second brake sets, said system comprising: a first differential pressure operated booster having first and second operating pressures; a first master cylinder actuatable by said first booster and having first and second brake actuating pressure outputs respectively connected to said first and second brake actuating circuits; a second differential pressure operated booster operatively connected with said first booster to receive said first and second operating pressures therefrom and having means acting only upon the establishment of operating pressures of a predetermined differential in said first booster to permit delivery of said differential operating pressures from said first booster to said second booster to operate said second booster; a second master cylinder actuatable by the operation of said second booster and having normally open valve means in said second brake actuating circuit fluidly intermediate said first master cylinder second brake actuating pressure output and the second brake set; said normally open valve means permitting brake actuating pressure to pass through said second master cylinder from said first master cylinder to the second brake set while open, and arranged to be closed by initial operation of said second booster, said second master cylinder being actuatable by operation of said second booster when said valve means is closed to pressurize the portions of said second brake actuating circuit from said second master cylinder to the second brake set in accordance with operation of said second booster; said second master cylinder having actuating pressure generating piston means therein actuatable by the force of operation of said second booster, said piston means having an effective area responsive to pressure from said first master cylinder second brake actuating pressure output when said valve means is closed to provide another actuating force on said piston means in addition to the actuating force of operation of said second booster.

Claim 5

A proportioning brake booster and master cylinder assembly comprising: a differential pressure operated primary brake booster having first and second operating pressures; a dual pressurizing chamber primary master cylinder having one pressurizing chamber connected to operate a vehicle rear wheel brake set and another pressurizing chamber connected to operate a vehicle front wheel brake set; a differential pressure operated secondary brake booster having the pressure operating chambers thereof fluid connected with their comparable pressure operating chambers of said primary brake booster, means for disconnecting one pressure operating chamber of said secondary brake booster from its primary brake booster comparable chamber during a first range of operation of said primary brake booster and for reconnecting the same during a second range of operation of said primary brake booster to actuate said secondary brake booster by said first and second operating pressures; a secondary master cylinder having a piston in a bore and dividing the bore into first and second pressure chambers and having a passage therethrough connecting said first and second pressure chambers, a normally open valve closing said passage upon actuation of said secondary brake booster, said first pressure chamber being connected in continuous fluid communication with the other pressurizing chamber of said primary master cylinder, said second pressure chamber being connected in continuous fluid communication with the vehicle front wheel brake set; said secondary brake booster actuating on said secondary master cylinder piston after closure of said valve to increase the pressure of fluid in said second pressure chamber and therefore increase the brake actuating pressure delivered to the vehicle front wheel brake set relative to the pressure delivered to the vehicle rear wheel brake set.

Claim 6

A proportioning brake booster and master cylinder assembly comprising: a differential pressure operated primary brake booster having first and second operating pressures; a dual pressurizing chamber primary master cylinder having one pressurizing chamber connected to operate a vehicle rear wheel brake set and another pressurizing chamber connected to operate a vehicle front wheel brake set; a differential pressure operated secondary brake booster having the pressure operating chambers thereof fluid connected with their comparable pressure operating chambers of said primary brake booster, means for disconnecting one pressure operating chamber of said secondary brake booster from its primary brake booster comparable chamber during a first range of operation of said primary brake booster and for reconnecting the same during a second range of operation of said primary brake booster to actuate said secondary brake booster by said first and second operating pressures; a secondary master cylinder having a piston in a bore and dividing the bore into first and second pressure chambers and having a passage therethrough connecting said first and second pressure chambers, a normally open valve closing said passage upon actuation of said secondary brake booster, said first pressure chamber being connected in continuous fluid communication with the other pressurizing chamber of said primary master cylinder, said second pressure chamber being connected in continuous fluid communication with the vehicle front wheel brake set; said secondary brake booster actuating on said secondary master cylinder piston after closure of said valve to increase the pressure of fluid in said second pressure chamber and therefore increase the brake actuating pressure delivered to the vehicle front wheel brake set relative to the pressure delivered to the vehicle rear wheel brake set.

Claim 7

In a brake booster system having a first assembly defined by a first brake booster and a first master cylinder actuatable thereby, the first brake booster having a power wall with a substantially constant pressure chamber on one side and a variable pressure chamber on the other side and means for varying the pressure in the variable pressure chamber to actuate the first booster and thus actuate the first master cylinder, the first master cylinder having first and second brake fluid pressurizing chambers for pressurizing brake fluid in separate brake circuits respectively containing first and second brake sets, the improvement comprising: a second assembly defined by a slave second brake booster and a second master cylinder actuatable thereby; said slave booster having a power wall with a substantially constant pressure chamber on one side and a variable pressure chamber on the other side and an output member movable by movement of said power wall and extending into said second master cylinder, said second master cylinder having a bore, a piston reciprocably movable in said bore and dividing said bore into a first chamber and a second chamber and having a hydraulic fluid passage extending therethrough and fluid connecting said first and second chambers, the end of said passage opening into said first chamber defining a valve seat and the end of said slave booster output member extending into said second master cylinder defining a valve element in said first chamber aligned to open and close said valve seat, spring means holding said valve element away from said valve seat until said slave booster is actuated and yielding upon actuation of said slave booster to permit closing engagement of said valve element with said valve seat to close said passage and prevent fluid transfer between said first and second chambers of said second master cylinder, said second master cylinder first chamber having a fluid inlet in continuous fluid cmmunication with said first master cylinder second chamber and said second master cylinder second chamber being in continuous fluid communication with said second brake set, said second master cylinder piston being movable by said slave booster output member upon actuation of said slave booster and closure of said valve seat to pressurize fluid in said second master cylinder second chamber, first conduit means providing continuous pressure communication between the substantially constant pressure booster chambers, second conduit means connecting the variable pressure booster chambers and having a first check valve maintaining said second conduit means open only so long as the pressure in said first booster variable pressure chamber is substantially the same as the pressure in said first and second booster substantially constant pressure chambers, a second normally closed check valve opened at a predetermined pressure change in said first booster variable pressure chamber to admit the pressure change to said second booster variable pressure chamber to actuate said second booster, said second brake set thereby being actuated initially by pressure from said first master cylinder second pressurizing chamber passing through said second master cylinder and subsequently by pressure generated in said second master cylinder second chamber by actuation of said second booster.

Claim 8

In a brake booster system having a first assembly defined by a first brake booster and a first master cylinder actuatable thereby, the first brake booster having a power wall with a substantially constant pressure chamber on one side and a variable pressure chamber on the other side and means for varying the pressure in the variable pressure chamber to actuate the first booster and thus actuate the first master cylinder, the first master cylinder having first and second brake fluid pressurizing chambers for pressurizing brake fluid in separate brake circuits respectively containing first and second brake sets, the improvement comprising: a second assembly defined by a slave second brake booster and a second master cylinder actuatable thereby; said slave booster having a power wall with a substantially constant pressure chamber on one side and a variable pressure chamber on the other side and an output member movable by movement of said power wall and extending into said second master cylinder, said second master cylinder having a bore, a piston reciprocably movable in said bore and dividing said bore into a first chamber and a second chamber and having a hydraulic fluid passage extending therethrough and fluid connecting said first and second chambers, the end of said passage opening into said first chamber defining a valve seat and the end of said slave booster output member extending into said second master cylinder defining a valve element in said first chamber aligned to open and close said valve seat, spring means holding said valve element away from said valve seat until said slave booster is actuated and yielding upon actuation of said slave booster to permit closing engagement of said valve element with said valve seat to close said passage and prevent fluid transfer between said first and second chambers of said second master cylinder, said second master cylinder first chamber having a fluid inlet in continuous fluid cmmunication with said first master cylinder second chamber and said second master cylinder second chamber being in continuous fluid communication with said second brake set, said second master cylinder piston being movable by said slave booster output member upon actuation of said slave booster and closure of said valve seat to pressurize fluid in said second master cylinder second chamber, first conduit means providing continuous pressure communication between the substantially constant pressure booster chambers, second conduit means connecting the variable pressure booster chambers and having a first check valve maintaining said second conduit means open only so long as the pressure in said first booster variable pressure chamber is substantially the same as the pressure in said first and second booster substantially constant pressure chambers, a second normally closed check valve opened at a predetermined pressure change in said first booster variable pressure chamber to admit the pressure change to said second booster variable pressure chamber to actuate said second booster, said second brake set thereby being actuated initially by pressure from said first master cylinder second pressurizing chamber passing through said second master cylinder and subsequently by pressure generated in said second master cylinder second chamber by actuation of said second booster.