Braking system with independent antilock control channels

摘要

A braking system includes a master cylinder that is operational to introduce a manually effected braking pressure in the braking system and includes a wheel brake that is responsive to the manually effected braking pressure. A modulator is interconnected in the braking system between the master cylinder and the wheel brake and includes a pump that has an inlet and an outlet wherein the inlet is in continuous open fluid communication with the wheel brake through a first fluid passageway. The first fluid passageway is free of any flow restrictive orifices and the first fluid passageway is not in fluid communication with an accumulator. The modulator also includes a normally open valve that is positioned in a second fluid passageway and the second fluid passageway extends between the wheel brake and both the pump outlet and the master cylinder. During base brake operation of the braking system, the pump and the valve remain unoperated so that the manually effected pressure is freely transmitted to the wheel brake. During ABS release operation, the pump is turned on and the valve is energized to close, blocking the second fluid passageway so that a reduced wheel brake fluid pressure is effected at the wheel brake and a rate of reduction of the wheel brake pressure is established that is directly proportional to, and from a mechanical effect standpoint, is a result solely of pump flow rate.