Abstract: A vehicle hydraulic braking system responds to detection of an operator intended high braking intensity event to isolate vehicle brakes from the master cylinder and activate a motor driven pump to generate a maximum predetermined supply pressure, calibrated to provide activation of an anti-lock braking system, to the brake apply valves for an initial predetermined time. Thereafter, the supply pressure is reduced via an electrically controllable pressure relief valve responsive to 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. The high intensity braking event is detected via a rate of change of master cylinder pressure, pedal force or pedal travel.

Abstract: A vehicle hydraulic braking system has a motor driven pump with an output to a brake apply valve and valve apparatus between a master cylinder and the brake apply valve capable of communicating or blocking master cylinder pressure from the apply valve. The valve apparatus further provides electrically controllable pressure relief to control supply pressure from the pump to the apply valve. A sensor indicating operator requested braking intensity is monitored to detect an operator intended high braking intensity event.

Abstract: A substantially constant brake assist gain is provided in a vehicle braking system having a vacuum booster providing braking assist to a brake fluid master cylinder in response to an operator input braking force, even though the gain of the booster falls off from its maximum value in a non-linear manner in a runout initiating portion of the working vacuum range near zero booster vacuum. A brake fluid pump, such as is used in an ABS/TCS modulator, is used to supplement the booster output as it falls so as to maintain a constant, linear brake system gain into runout. In the runout initiating portion of the working vacuum range, a runout assist gain is derived from stored data expressing booster assist gain as a function of booster vacuum, and a target wheel pressure is calculated from the derived runout boost assist gain and a corresponding change in master cylinder pressure.