Patent GB-907085-A (GB)
Title: Fluid flow control valves
IPC: F15B21/047
Filed: 1960-12-20
Abstract: 907,085. Valves. NEW YORK AIR BRAKE CO. Dec. 20, 1960 [May 9, 1960], No. 43713/60. Class 135. A fluid motor control valve is provided with a device for preventing the flow of exhaust fluid from the motor exceeding the rate of flow of the supply fluid delivered by the pump to the motor. The control valve 11 has an inlet, an exhaust and two motor ports (not shown). A bore 19 is provided housing the movable valve member 32. The bore 19 is provided with annular chambers 21, 22, 23, 24, 25, 21<SP>1</SP>, 22<SP>1</SP>, 23<SP>1</SP>. Chambers 23, 24, 23<SP>1</SP> are in communication with the inlet port, chambers 21, 21<SP>1</SP>, 25 are in communication with the exhaust port via a manifold 29, while chambers 22, 22<SP>1</SP> communicate respectively with the motor ports. The device controlling the flow of exhaust fluid comprises a valve member 46, movable in a bore 39 of the valve member 32 and loaded by a spring 65. The member 46 is provided with a restricted through flow passage 54 connecting two pressure chambers 52, 53. Passages 55 in the member 32 provide unrestricted flow from an annular chamber 33, in the member 32, to chamber 52 while a passage 56 containing the end of a spring member 57 provides restricted flow from a chamber 34 to the pressure chamber 52. The restricted path 56 is about four times as great as the restriction affords by passage 54. A non- return valve 62 is provided to prevent flow from chamber 53 to chamber 52. With the valve member 32 in the position shown, fluid is supplied to chamber 22 while chamber 22<SP>1</SP> is connected to exhaust in the following manner. The fluid supply is fed to an annular chamber 23 and passes through passages 55 to pressure chamber 52. The restricted flow through passage 54 to the chamber 53 sets up a pressure differential between the chambers 52, 53 which, at a predetermined value, moves the valve member 46 to the left and allows flow from chamber 23 to chamber 22 and hence to the motor through an annular groove 48 on the member 46. The exhaust of fluid from chamber 22<SP>1</SP> is controlled by a valve 46<SP>1</SP> of the same design as valve 46. Fluid pressure on the inlet in chamber 231 passes to chamber 52<SP>1</SP> through the restricted passage 56<SP>1</SP>, the passage 55<SP>1</SP> being closed to the inlet. The fluid in chamber 52<SP>1</SP> passes through restricted passage 54<SP>1</SP> to chamber 53<SP>1</SP> which also communicates with chamber 21<SP>1</SP> through passage 581. At a certain pressure differential in chambers 52<SP>1</SP>, 531 the valve 46<SP>1</SP> moves to the right to connect chambers 22<SP>1</SP>, 21<SP>1</SP> through groove 481. Due to the difference in size in the passages 55, 56<SP>1</SP> the pressure differential necessary in chambers 23, 22 to move valve 46 will be less than that in chambers 23<SP>1</SP>, 21 necessary to move valve 461. If, due to the external load, the exhaust flow increases above the supply, the supply pressure will drop and hence the pressure in chamber 23<SP>1</SP> will drop, this will cause the valve 46<SP>1</SP> to move to the left to throttle or close the flow from 22<SP>1</SP> to 21<SP>1</SP> through the groove 48<SP>1</SP>.