Patent ID: 6623088
Filing Date: 2003-09-23
Classification: B60T,Y10S

Abstract:
Method of controlling a vehicle hydraulic braking supply pressure in a vehicle braking system having a wheel brake, an apply valve for applying the supply pressure to the wheel brake when opened and isolating the wheel brake from the supply pressure when closed, a brake pedal, a master cylinder responsive to the brake pedal to generate a master cylinder pressure, a motor driven hydraulic pump having an outlet to the apply valve and hydraulic valve means connected between the master cylinder and the apply valve and having a first condition providing open hydraulic pressure communication from the master cylinder to the apply valve and a second condition preventing hydraulic pressure communication from the master cylinder to the apply valve, the method comprising the steps:providing the hydraulic valve means with an electrically controllable pressure release valve permitting controlled pressure relief from the pump to the master cylinder; providing a sensor indicative of operator requested braking intensity and monitoring the sensor to detect an operator intended high braking intensity event; upon detection of the operator intended high braking intensity event, performing the following additional steps: (1) placing the hydraulic valve means in its second condition; (2) operating the pump and controlling the electrically controllable pressure release valve to generate a maximum predetermined supply pressure to the apply valve for an initial predetermined time; (3) sensing vehicle deceleration; (4) after the initial predetermined time, controlling the electrically controllable pressure release valve responsive to the sensed vehicle deceleration so as to decrease the supply pressure provided to the apply valve to a level just sufficient to provide the sensed vehicle deceleration, wherein the vehicle braking system has an anti-lock brake control responsive to wheel spin to control the apply valve to modulate the supply pressure so as to reduce wheel brake pressure and minimize the wheel spin and wherein the maximum predetermined supply pressure is calibrated to produce the wheel spin and thus activate the anti-lock brake control.