Hydraulic brake booster

A brake booster comprising:

• a housing defining an axial bore therein;
• a boost piston slidable in said bore and cooperating with said housing to define a boost chamber;
• an input member selectively movable by an operator;
• an input piston slidable in said bore, said input piston and said boost piston cooperating with said housing to define a pedal chamber, said input member contacting said input piston to selectively urge said input piston in a first direction, said boost piston being urged in said first direction as a consequence of said input piston moving in said first direction;
• an output member adapted to operatively connect said boost piston to a master cylinder piston of a brake system master cylinder;
• a controller for selectively admitting a pressurized hydraulic fluid into said boost chamber to urge said boost piston to move such that said boost piston exerts a second force on said output member which is greater than said first force;
• a first fluid conduit through which said controller supplies said pressurized hydraulic fluid to said pedal chamber;
• a second fluid conduit providing fluid communication between said first fluid conduit and said boost chamber, wherein a check valve is disposed in said second fluid conduit permitting hydraulic fluid to flow through said check valve in a direction to said boost chamber and preventing hydraulic fluid from flowing through said check valve in a direction from said boost chamber to said first fluid conduit;
• and
• a third fluid conduit providing fluid communication between said first fluid conduit and said boost chamber around said check valve, said third fluid conduit including an orifice restricting the flow of hydraulic fluid in said third fluid conduit.

A brake booster comprising:

• a housing defining an axial bore therein;
• a boost piston slidable in said bore and cooperating with said housing to define a boost chamber;
• an input member selectively movable by an operator;
• an input piston slidable in said bore, said input piston and said boost piston cooperating with said housing to define a pedal chamber, said input member contacting said input piston to selectively urge said input piston in a first direction, said boost piston being urged in said first direction as a consequence of said input piston moving in said first direction;
• an output member adapted to operatively connect said boost piston to a master cylinder piston of a brake system master cylinder;
• a controller for selectively admitting a pressurized hydraulic fluid into said boost chamber to urge said boost piston to move such that said boost piston exerts a second force on said output member which is greater than said first force;
• at least one fluid conduit between a source of said pressurized hydraulic fluid and a reservoir of relatively unpressurized hydraulic fluid;
• a first pressure control valve situated in said fluid conduit and responsive to said controller for selectively supplying said pressurized hydraulic fluid from said fluid conduit to said pedal chamber and venting from said pedal chamber to said reservoir;
• and
• a second pressure control valve situated in said fluid conduit and responsive to said controller for selectively supplying said pressurized hydraulic fluid from said fluid conduit to said boost chamber and venting from said boost chamber to said reservoir.

A brake booster adapted to be operated by a brake pedal, said brake booster comprising:

• an input rod adapted to be operatively connected to the brake pedal, said input rod movable in a first direction when the brake pedal is actuated;
• a housing having a bore formed therein;
• an input piston disposed in said bore of said housing, said input rod directly engaged with said input piston such that said input piston moves with said input rod when said input rod is moved in said first direction;
• a boost piston disposed in said bore of said housing;
• wherein said bore, said input piston, and said boost piston define an input chamber in fluid communication with a source of pressurized fluid such that an increase in pressure of said input chamber urges said boost piston in said first direction and urges said input piston in a second opposite direction;
• and
• wherein said bore and said boost piston define a boost chamber in fluid communication a source of pressurized fluid such that an increase in pressure of said boost chamber urges said boost piston in said first direction.