Fluid pressure control valves

摘要

902,321. Fluid-pressure brakes. BENDIXWESTINGHOUSE AUTOMOTIVE AIR BRAKE CO. Aug. 31, 1960 [Oct. 5, 1959], No. 30061/60. Class 103 (1). [Also in Group XXIX] Upon admitting control fluid to a cavity 26 via a port 18 during operation of a valve, e.g. a brake valve, a diaphragm 30 is lowered to seat a hollow exhaust closure 36 on the upper end of another valve closure 42 so disconnecting an exhaust port 20 from a compressed air delivery cavity 24. Continued movement of the closure 36 displaces the closure 42 from a seat 43 to connect an inlet cavity 22 with the cavity 24 whereby fluid flows from both a port 16 to the device to be actuated, and a port 60 to a cavity 35 beneath the diaphragm 30; when the delivery pressure acting on the various areas exposed thereto equals the control pressure on the upper side of the diaphragm the whole assembly is elevated by light springs 41, 46 until both closures lap. The closure 42 is stepped and slides in chambers 52, 58, the former being open to atmosphere and the latter connected to the cavity 35. Balancing is effected by making the upper part 50 of the closure 42 the same diameter as the seat 43, and the annular area of the closure 42, around the closure 36, equal to that of the lower end 56 thereof; alternatively the upper side of the diaphragm is of greater area than that of lower side, including the area of the closure exposed to the delivery pressure, and the end 56 is larger than the annular area of the closure 42. In a modification, the diaphragm 30 is replaced by a piston, and the balancing is effected in chamber 52 instead of chamber 58, which balancing chamber opens to the sealing surface of the closure 42 via passages through the larger diameter part 50 thereof.