Patent ID: 7921763

Claim:
Brake control system for a motor vehicle comprising a brake pedal ( 1 ), a brake booster ( 4 ) which comprises a front chamber ( 40 ) and a rear chamber ( 41 ) which are separated by a booster piston ( 42 ), said booster ( 4 ) supplying an amplified braking command dependent on the pressure difference between the two said chambers, a brake master cylinder ( 5 ) receiving the amplified braking commands from the brake booster ( 4 ), characterized in that it comprises a simulator ( 3 ) coupled pneumatically or hydraulically to the piston ( 42 ) of the brake booster ( 4 ), said simulator ( 3 ) receiving at least one braking command from the brake pedal ( 1 ) and in return establishing or controlling a pressure difference between the front chamber ( 40 ) and the rear chamber ( 41 ) of the brake booster so as to control the movement of the piston ( 42 ), characterized in that it comprises a pneumatic servomotor for controlling a pneumatic brake booster or brake servo, characterized in that said control servomotor comprises a space ( 8 ) comprising a first bore ( 89 ) in which there slides a three-way valve piston ( 30 ) equipped with a three-way valve capable of: placing the rear chamber ( 41 ) in communication with the front chamber ( 40 ); or of isolating the rear chamber ( 41 ) from the front chamber ( 40 ); or of placing the rear chamber ( 41 ) in communication with a pressure source that establishes a pressure difference between the front chamber and the rear chamber, characterized in that a first region ( 89 A) of the first bore ( 89 ) lying on one side of the three-way valve piston ( 30 ) is substantially at the same pressure as the front chamber, and in that a second region ( 89 B) of this bore ( 89 ), lying on the opposite side of the rear chamber ( 41 ) to the three-way valve piston ( 30 ) is substantially at the same pressure as the rear chamber, characterized in that said space ( 8 ) has a first end lying in the rear chamber ( 41 ) of the booster, near to said booster piston ( 42 ), and a second end lying on the opposite side of the booster wall ( 46 ) to the side to which the brake master cylinder is attached, and in that the first region ( 89 A) of the first bore ( 89 ) lies between said three-way valve piston ( 30 ) and the first end, while the second region ( 89 B) of the first bore ( 89 ) lies between the three-way valve piston ( 30 ) and the second end, characterized in that said space ( 8 ) comprises a second bore ( 31 ) situated on the same side as the first end of the chamber ( 8 ) and in which there slides a control piston ( 34 ) which is controlled by the brake pedal ( 1 ) and which controls the axial movement of the sensor ( 302 ) of the three-way valve, this second bore also comprising an elastic element ( 310 ) which offers elastic resistance to the movement of the control piston ( 34 ), characterized in that the second bore ( 31 ) contains a fluid, characterized in that the second bore is supplied with fluid from a brake fluid reservoir.