Fluid pressure control valve

摘要

917,180. Fluid-pressure brakes. BENDIX CORPORATION. Aug. 30, 1960 [Oct. 30, 1959]. No. 29932/60. Class 103 (1). [Also in Group XXIX] A control valve for a fluid-pressure braking system has a closure member 50 urged by a coil spring 52 to sealing engagement with a valve seat 42 and which may be disengaged therefrom with a tilt action by a member 46 having a line of force falling within the area bounded by the seat and off-centre with respect to that of the spring. When the brakes are to be applied, the pressure in a passage 26 having a connection 20 with the master brake cylinder is increased to displace a piston 28 and the tubular member 46 to the right until engagement with the closure member 50 isolates chamber 34 and the space 18 with which it is connected from chamber 32 communicating with a vacuum connection 14 through a passage 16 and a space 12. Further movement to the right lifts the member 50 to permit air to flow into the space 18 and drive the piston B to the right so that fluid is expelled by a piston 10 from an hydraulic cylinder D into the braking system, the piston 10 closing a fluid supply valve 24 during its movement. When the pressure ceases to increase in the passage 26 increased air pressure on a diaphragm 44 causes the member 46 to move to the left until the member 50 re-seats while a decrease of pressure in the passage 16 causes the member 46 to move further to the left into the position shown until the differential pressure on the diaphragm 44 has decreased sufficiently for the lower hydraulic pressure to re-engage the member 46 with the member 50. The member 46 applies a lifting force to the member 50 eccentric to that applied by the loading spring 52 so that the member, which is of resilient material, such as neoprene, is deformed and tilted as it lifts. A snap-ring 58 in the periphery of the member slides on axial guide surfaces 60 formed in the walls of the chamber 36. The loading spring may have coils of the same diameter with the distance separating each of the coils along one side of the spring being less than that on the opposite side so that a higher force is applied at one side of the member 50 than at the other or the coils may be of progressively increasing diameter to make the centres of the end coils offset with respect to each other. If a spring with a partial end coil is used a stiffening ring is provided in the member 50 or is positioned between it and the spring. Specification 692,007 is referred to.