Patent ID: 8651587

Claim:
An electronically controlled hydraulic brake system comprising: a driver-operated pressure generator displacing brake fluid into a brake circuit, a wheel brake, a brake line connecting the pressure generator to the wheel brake, a low-pressure accumulator, a relief line from the wheel brake to the low-pressure accumulator, a self-priming pump with a suction side and a pressure side, a suction line from the low-pressure accumulator to the suction side, a pressure retention valve assembly in the suction line, a pressure line from the pressure side of the pump to a junction with the brake line between the pressure generator and the wheel brake, a supply line from the brake line from the pressure generator to the suction line, and wherein the pressure retention valve assembly is actuatable to two conditions, a first condition which allows a flow of brake fluid from the low-pressure accumulator to the suction side of the pump and has a pressure retention bias requiring a pressure difference of at least 0.5 bar to allow the flow of brake fluid, and a second condition which disables the pressure retention bias wherein the pressure retention valve assembly comprises a two-position valve having a normal position and an activated position, the normal position corresponding to one of the conditions and the activated position corresponding to the other of the conditions; and wherein one of the two positions of the two-position valve assembly allows a bidirectional flow of brake fluid through the suction line in the second condition.