US 6,981,438 B1
Hydraulic brake booster
Timothy Jay Albert, Niles, Mich. (US); and Robert K. Wilson, Galine, Mich. (US)
Assigned to Robert Bosch Corporation, Broadview, Ill. (US)
Filed on Jan. 29, 2004, as Appl. No. 10/767,300.
Int. Cl. F15B 13/10 (2006.01); F15B 13/16 (2006.01)
U.S. Cl. 91—367 7 Claims
OG exemplary drawing
 
1. A hydraulic brake booster for use in a brake system having a housing with a first bore for retaining a power piston, a second bore for retaining a control valve and an actuation chamber, said second bore being connected to a source of pressurized fluid, a reservoir and said actuation chamber, said control valve including a first cylindrical member and a second cylindrical member retained in said second bore, said first cylindrical member having a stepped bore that extends there through and a first sleeve located in said stepped bore to control communication between an inlet port, a supply port and a relief port in said housing, an actuator arrangement including a ball located in said stepped bore and a pin retained in said second cylindrical member, said pin having a first end being located in said actuation chamber and connected with a first input member and a second end that extends into said stepped bore to engage said ball, said first end on receipt of a first input force initially moving said pin and ball from a position of rest to interrupt fluid communication between said actuation chamber and said reservoir through said relief port and thereafter moving said first sleeve to selectively initiate communication of pressurized fluid presented to said inlet port to said actuation chamber that acts on said first piston as a function of said first input force to effect a first brake application of a wheel brake, said pin and ball returning to said position of rest on termination of said first input force, said actuator arrangement being further characterized by a second sleeve that surrounds said pin with a lip on a first end that engages said second cylindrical member to position a second end thereof in an auxiliary actuation chamber in said second cylindrical member, said second sleeve responding to a second input force derived from pressurized fluid being presented to said auxiliary actuation chamber as a function of a second input and acting on said second end of said second sleeve to move said first end into engagement with said ball and move said ball from a position of rest to interrupt fluid communication between said actuation chamber and said reservoir through said relief port and thereafter moving said first sleeve to selectively initiate communication of pressurized fluid presented to said inlet port to said actuation chamber that acts on said first piston as a function of said second input to independently effect a second brake application of a wheel brake, said ball returning to said position of rest and said second sleeve returning to engagement with said second cylindrical member on termination of said second input force.