Patent GB-600464-A (GB)
Title: Improvements in fluid pressure supply systems
IPC: F15B1/027
Filed: 1944-08-01
Abstract: 600,464. Fluid-pressure servomotor-control systems. BENDIX-WESTINGHOUSE AUTOMOTIVE AIR BRAKE CO. Aug. 1, 1944, No. 14694. Convention date, Aug. 4, 1943. [Class 135] In the fluid compressing system according to Specification 567,898, [Group XXVIII], i.e. one in which a high pressure reservoir is charged by a compressor solely from a low pressure reservoir when the pressure in the latter has attained a predetermined value, additional valve means 63 are provided which, when the pressure in the high pressure reservoir exceeds a predetermined value, connect the outlet and inlet of the compressor together directly by a path which does not pass through either of the reservoirs. Valve means 17, 44 are also provided (1) to cut off the discharge port of the compressor from the low pressure reservoir and connect it to the high pressure reservoir when the pressure in low pressure exceeds a predetermined value, and (2) to connect the low pressure reservoir to the inlet of the compressor when the said predetermined value is exceeded. As shown, a compressor 8 supplies a low pressure reservoir 6 through conduits 15 and 16 and a high pressure reservoir 7 through conduits 15 and 18, the latter containing a check valve 20 which prevents return flow from the reservoir 7. The low pressure reservoir 6 is connected to the inlet port 10 of the compressor through conduits 42, 43 and 11. The conduit 18 is likewise connected to the inlet port 10 through conduits 62, 43 and 11. The inlet port 10 is connected with the atmosphere through the conduits 11, 43, 12 and a check valve 13. The three valve mechanism 17, 44, 63 respectively are similar and each comprise a valve member such as 29 carried on a stem such as 30 attached to a spring-loaded diaphragm such as 32 exposed at one side to atmospheric pressure and at the other side to the pressure in a control chamber such as 36. The two valve mechanisms 17, 44 are controlled in common by a known type of pressure-responsive governor 39 which normally vents conduits 41, 59 connected to the control chambers of the valve mechanisms 17, 44 respectively, but which operates to connect these conduits with the low pressure reservoir 6 when the pressure in the latter exceeds a predetermined value. The mechanism 63 is similarly controlled by a pressure-responsive governor 79 in accordance with the pressure in the high pressure reservoir 7. In operation, when the pressure in the low pressure reservoir 6 exceeds the predetermined value, the valve mechanisms 17, 44 are operated together, the former to disconnect the conduits 15, 16 and to connect the conduits 15, 18 and the latter to connect the conduits 42, 43 so that the compressor now draws fluid from the low pressure reservoir to feed the high pressure reservoir. This continues until the pressure in the low pressure reservoir again falls below the predetermined value, whereupon the mechanisms 1.7, 44 return to their original positions and the compressor diverts its discharge once more to the reservoir 6. This alternate discharge to the two reservoirs continues until the pressure in the high pressure reservoir 7 exceeds its predetermined value, whereupon the valve mechanism 63 operates to connect the conduits 62 and 43 and thus unload the compressor which remains so unloaded until the pressure in the high pressure reservoir again falls below the predetermined value. The fluid in the reservoir 7 is utilised to operate a power cylinder 82 under the control of a self-lapping valve mechanism 87 of the kind described in Specification 543,778. The exhaust from the power cylinder 82 is returned to the reservoir 6 by conduits 86, 91.