Patent GB-536708-A (GB)
Title: Improvements in or relating to fluid pressure remote control systems
IPC: F15B11/16
Filed: 1940-03-13
Abstract: 536,708. Pneumatic single-stroke apparatus. AUTOMOTIVE PRODUCTS CO., Ltd., and THORNHILL, P. W. March 13, 1940, No. 4735. [Class 8(ii)] [Also in Group XXIX] A fluid pressure remote control system of the kind in which motor units, such as are used on aircraft to control flaps, undercarriages &c. are operated by fluid pressure generated by a pump Fig. 1 and stored in an accumulator B, is constructed with a shut-off valve between the accumulator and the selector valves which control the motors, the valve being adapted to close if the pressure in the accumulator drops below a pre-determined value but being capable of operation by a manual control to permit of the operation of the motors after the valve has closed automatically. As applied to a control system as in Specification 533,667 in which selector valves E arranged between supply lines C, H, are operated by control valves K, the pressure supply line C is connected to the accumulator by means of pipes connected to screw unions 16, 13, and a valve A which is shown in its closed position in Fig. 1. The valve A comprises a sliding sleeve 18 which moves in a reduced part 17 of a bore 11 in the valve casing, and is carried by a large end 20 having a sliding fit in the bore and operated on by a spring 22 which is weaker than a spring 32 which before fluid pressure is applied moves a two-part plunger 25 to the right so that a packing 27 on this plunger forms a sealed joint with the end of the sleeve 18 and prevents fluid from reaching the accumulator. When pressure is admitted to the groove 17, the plunger 25 is moved back by the fluid pressure, and the fluid passes to the accumulator and also has access via a passage 37, a second bore 12 in the valve casing and then through a filter 46 and narrow passages 40, 42, 44, to the end space 30 of the bore 11 in which the reduced part of the plunger 25 moves. As the pressure in the space 30 increases the pressure tending to open the valve becomes counterbalanced, and when the actual pressure in the accumulator drops below a given valve (2,000 lb. per square inch sag) the valve closes under action of the spring 32. If it is required to actuate one of the motors J when the valve is closed the valve may be re-opened by actuation of a hand-operated valve L to connect the space 30 to the reservoir F of the pump D thus relieving the valve A of the counterbalancing pressure. The valve L comprises a valve 57 which is carried by a plunger 60 normally raised by a spring 59. The fluid pressure on the valve is normally balanced and the operator has to overcome the spring only to operate the valve L. A simpler form of valve may be used as in Fig. 3, in which the selector valve E is arranged between the shut-off valve A and the return pressure line, and is directly manually operated valve. The accumulator B is in this case charged through a cut-off valve G and a non-return valve M. The filter is dispensed with and the plunger 25 is bored throughout at its forward end with a nipple 66 formed with a fine bore, the nipple serving to hold in place the valve washer 27 which engages direct with the reduced position 17 of the bore 11 to close the connection between the member B. E.