GB527171A - Improvements in or relating to liquid pressure remote control systems - Google Patents

Abstract

527,171. Pneumatic single-stroke apparatus. AUTOMOTIVE PRODUCTS CO., Ltd., and THORNHILL, P. W. April 1, 1939, No. 10269. [Class 8 (ii)] [Also in Group XXIX] A fluid pressure remote control system in which a slave unit comprising a piston controls mechanism such as the landing flaps of aircraft is constructed with a control valve 21 such as is described in Specification 480,180, [Group XXIX], in which the valve is operated by a lever 15 normally held in " off " position by a spring plunger 28 and automatically returned to " off" " position when the pressure in the slave unit member reaches a predetermined value in excess of the normal working pressure, and the arrangement is such that this can take place in positions intermediate the extreme positions of the piston of the slave unit. The fluid is supplied by a continuous pump 10 supplied by a return pipe 13 or from a reservoir 14, and the valve 21 can be set to supply fluid through pipes 16, 17 to either end of the cylinder 40 in which works a tubular plunger 42 connected to the member to be operated, the plunger having a piston head 43 having an end wall 44 serving to close partly the front end of the piston plunger 42. The fluid normally passes into the cylinder 40 from pipe 16 via a passage 49 in a stem 47 fixed to the cylinder, and through an aperture 45 in the wall 44. When this aperture reaches an enlarged head 46 in the stem 47 the flow is restricted and the rise in pressure causes the valve lever 15 to move to " off " position and the actuated member is halted in an intermediate position. If however the valve lever is held by hand in the " on " position the motion of the piston continues under the action of fluid admitted through a relief valve 50 which is set to open at a pressure slightly above that required to operate the valve lever 15. When the piston is returned by fluid admitted to the other end of the cylinder it is again halted in the intermediate position, and a valve 52 performs the same function as valve 50. By arranging several heads as 46 the piston may be halted in several intermediate positions. In a modification, Fig. 4, the piston 43 is moved freely to the right by fluid admitted through a valve 55a with a weak spring. On the return to the left the piston is stopped when its head 44, which fits closely to the guide stem 49, passes over aperture 57 in the stem, the outlet through which is restricted thus causing increase of pressure and operation of lever 15. In modifications the increase in pressure necessary to operate the lever 15 in intermediate positions may be produced by an auxiliary valve device worked mechanically from the slave unit or member controlled thereby.