Patent ID: 6302497
Filing Date: 2001-10-16
Classification: B60T

Abstract:
A vehicle brake control system comprising:a brake booster including an interior and a power piston assembly arranged such that the interior of the brake booster is divided into a constant pressure chamber and a variable pressure chamber selectively communicating with said constant pressure chamber, said brake booster further including a first servo mechanism designed to develop a differential pressure between said constant pressure chamber and said variable pressure chamber in response to operation of a brake pedal to produce a force corresponding to the amount of operation of the brake pedal, and a second servo mechanism;a master cylinder operatively connected to said brake booster to create hydraulic pressure in response to an output of said brake booster;a plurality of wheel cylinders for applying a braking force to respective wheels in response to the hydraulic pressure;a plurality of hydraulic lines connected between said master cylinder and said wheel cylinders;a plurality of corresponding pressure charging valves provided in said hydraulic lines to allow and to block communication between said master cylinder and said wheel cylinders;a plurality of pressure relief valves connected to said hydraulic lines between said pressure charging valves and said wheel cylinders;an accumulator selectively communicating with said wheel cylinders through said pressure relief valves; anda controller designed to control said second servo mechanism, said pressure charging valves and said pressure relief valves, said controller being operable to cause said second servo mechanism to develop a differential pressure between said constant pressure chamber and said variable pressure chamber, regardless of whether or not the brake pedal is depressed, to thereby produce a force greater than that corresponding to the amount of operation of the brake pedal, said controller being further operable to:open said pressure charging valves and close said pressure relief valves so as to increase a flow of brake fluid from said master cylinder to said wheel cylinders thereby increasing hydraulic pressure applied to said wheel cylinders;close said pressure charging valves and open said pressure relief valves so as to generate a flow of brake fluid from said wheel cylinders to said accumulator thereby decreasing hydraulic pressure applied to said wheel cylinders; andopen said pressure charging valves and open said pressure relief valves so as to generate a flow of brake fluid from said accumulator to said master cylinder.