GB781284A - Improvements in or relating to control systems for the sequential operation of two or more fluid-pressure operated piston and cylinder assemblies - Google Patents

Abstract

781,284. Engine valve-gear. UNITED STATES METALLIC PACKING CO., Ltd. July 12, 1954 [May 7, 1953], No. 12702/53. Class 122 (2). [Also in Groups XXVIII and XXIX] The Provisional Specification describes a fluid pressure operated piston engine having valve gear comprising a main distributing valve 10 actuated by pressure fluid controlled by pressure-fluid operated differential pilot valves 37, 38 controlled by movement of the engine piston 33 relative to ports 32, 32<SP>1</SP> in its cylinder 22. The main valve 10 comprises a piston valve 11 in a cylinder 12 having a pressure fluid inlet port 17, two exhaust ports 23, 24, two end ports 15, 16 respectively connected to ports 36<SP>1</SP>, 36 of pilot valves 37, 38, and two further ports 18, 19 each connected to one end of the cylinder 22 via ports 20, 21 and to the outer ends of one of the pilot valves 38, 37 which are connected at their inner ends to the ports 32<SP>1</SP>, 32 in the cylinder wall. Each pilot valve has a piston formed by a smaller diameter portion 27 that controls the port 36 and a larger diameter portion 30, the space between the two portions being vented through a port 35. In operation, when the main piston valve 11 is in its lower position as shown, pressure fluid flows through the port 19 to force the piston 33 down and hold the pilot valve piston 28 in its left or normal terminal position in which the upper end of the main valve is connected to exhaust through ports 36, 35; the lower end of the cylinder 33 being open to exhaust through ports 20, 18 and 24. As the piston 33 reaches the inner end of its stroke it uncovers the port 321 and the pilot valve 37 is moved to the right, as shown, to allow pressure fluid to flow through ports 361, 15 and force the main valve 11 upwards. The upper end of the cylinder 22 and the outer end of the pilot valve 38 are then connected to exhaust through ports 19 and 23 and fluid is supplied through ports 17 and 18 to act on the larger portion 30<SP>1</SP> of the piston of the pilot valve 37, which is thereby returned to its normal position, and to force the piston 33 upwards until it uncovers the pilot port 32 and the piston of pilot valve 38 is moved to the right so that pressure fluid flows through ports 36 and 16 and forces the main valve to its lower position and the cycle recommences; the pilot valve piston 28 being returned to its normal position by fluid acting on its larger portion 30.