Brake pressure modulator valves in motor vehicle brake systems

摘要

1,120,137. Anti-skid braking system. GENERAL MOTORS CORP. 10 June, 1966 [13 Aug., 1965, No. 25948/66. Heading F2F. A motor vehicle braking system comprises a master cylinder connected to the front wheel brakes 20 and to the fluid inlet of a brake pressure modulator valve 12, the rear brakes 16 are connected to the valve outlet, the modulator valve including a cut-off valve 28 controlling communication between the inlet and outlet and acted upon by a servomotor 32, high and low pressure ports 58, 22 being connected to opposite sides of the servomotor by a movable valve element 50 in a rest position thereof, a skid sensor is connected to supply a signal input at 24 when skidding occurs to move the valve element to reverse the connections to the servomotor which permits movement of the cut off valve into a position interrupting communication between the fluid inlet and outlet. Fig. 2 shows the modulator valve in its normal position, servomotor chamber 36 being connected by passages 62, 60, 40 to a vacuum source and chamber 34 to atmosphere by passages 64, 54, 56 and filter 58. The low pressure connection at 22 acts also on the left side of diaphragm 46 to maintain the valve element 50 in its appropriate leftwards position. The servomotor then maintains cut off valve 28 in an open position whereby on actuation of the master cylinder fluid can flow through inlet 10 and outlet 14 to the rear brakes. When the skid sensor operates to deliver a signal at 24 in the form of a pressure pulse valve element 50 moves rightwards to reverse the servomotor pressure connections, the member 30 moving rightwards to allow valve 28 to seat and interrupt communication with the rear brakes. The movement of member 30 also increases the volume of the rear brake line. On cessation of the signal the valve parts revert to their previous positions. The signal input from the sensor, by the path 24, may be a sub- or super-atmospheric pulse or the path may be a mechanical link. In another embodiment the valve is modified to accept a source of super-atmospheric pressure in place of the vacuum source.