Fluid distributing valves

摘要

1,032,908. Valves. NEW YORK AIR BRAKE CO. March 15, 1965 [July 17, 1964], No. 10836/65. Heading F2V. A parallel arrangement of control valves has a block 11, Fig, 1, with bores for three-position spool-valves A, B, and C, an inlet chamber 15 and an exhaust chamber 18 with limbs 19, 21 intersecting the opposite ends of each valve bore; branch passages 16, 17 leading from the inlet chamber 15 also intersect the valve bores. Each bore is also connected to an open-centre path 22-25 in the valve neutral-position shown, which connects a carry-over port 14, Fig. 2, to the chamber 15, Fig. 1. The valves are identical and each incorporates two lands 31, 32 that are hollow and intersected by radial passages 33, 34 and 35, 36, respectively; each land controls a motor port 26, 27. The exhaust chamber 18 opens into a port 13 (Fig. 2, not shown) and surmounts a further chamber 37 connected to the inlet branches 16, 17, Fig. 1, and with the exhaust chamber 18 via a spring-loaded valve 43, the stem 41 of which is hollow and contains radial ports 47 and leads to the port 13. The ports 47 co-operate with a web that divides the chamber 18 into upper and lower sections 18U, 18L. When one or more of the valves is operated so that movement of a ram connected to the ports 26, 27, is opposed by the applied load the valve 43 remains in the position shown and the ports 47 conduct the exhaust fluid to port 13. Should opposite motion of the ram result in cavitation, the supply pressure in chamber 37 falls below that in exhaust chamber 18 and the valve 43 opens and ports 47 are restricted so increasing the back-pressure in chamber 18 and causing fluid to flow through valve 43 into chamber 37 to supplement the inlet fluid. In a modification, the spool valves are arranged in series-parallel and the carry-over port is dispensed with. The chamber 371 (Fig. 5, not shown), is connected directly to the inlet chamber 151 whilst the stem 441 has two sets of radial ports 64, 65 which coact with corresponding ports 62, 63 in a sleeve 61. The stem is freely rotatable in the sleeve 61 and the ports 64 are offset relative to the ports 65 so that flow to the exhaust port 131 is never cut-off or unduly restricted.