Patent GB-595547-A (GB)
Title: Improvements in means for starting reciprocating internal combustion engines
IPC: C09D11/10
Filed: 1942-10-28
Abstract: 595,547. Combustion-product plant; starting. ENGLISH ELECTRIC Co., Ltd., and WELSH, R. J. Oct. 28, 1942, No. 15122. [Classes 7 (i) and 7 (v)] In a power plant including a free-piston internal-combustion engine and means for starting the engine by applying compressed air, including automatic means for moving the pistons towards outer dead-centre position ready for starting, a starting relay responsive to a fluid-pressure or electric starting signal controls the application of the compressed air and its action is prevented unless the engine is at rest with its pistons in starting position. As shown, engine is of the opposed-piston type, each piston unit comprising a power piston 4, compressor piston 5 and buffer piston 6, air from the compressor cylinders 2 being conveyed by pipes 15 to the annular space around inlet ports la in the combustion cylinder 1 and piston-controlled exhaust ports 1b being connected by a pipe 16 to a turbine or other prime mover. A cam 11 actuating a fuelinjection pump 10 connected to fuel injectors 9 on the cylinder 1 is driven by a lever 20 connected by a link 21 to synchronizing links 7 connecting the pistons 5 to a lever 8 pivoted upon the cylinder 1. Starting is effected by the admission of compressed air from a pipe 23 through a non-return valve 22 to each buffer cylinder 3, each piston unit having been moved to the outer end of its stroke, upon the stopping of the engine, by a barring piston 24 actuated by fluid pressure in a pipe 26. This pressure also serves to open a relief valve 27 on each buffer cylinder. The cylinders 3 also have terminal vent ports 3a. The admission of pressure fluid to the pipe 26 is controlled by a " barring relay " valve comprising pistons 30, 31 in a cylinder 32 connected at one end by a pipe 33 to an end-ofstroke indicator 35 and to a running indicator 37, while the other end is connected by a pipe 4b to the end-of-stroke indicator 35. The running indicator 37 comprises a piston valve 36 actuated by a link 28 from the lever 8; in its extreme positions, with the engine at rest, the valve 36 admits pressure fluid from a pipe 38 through a restricted orifice 37a or 37b to one or other of two cylinders in the body 37, actuating pistons 39; 40 whereby pressure is admitted to the pipe 33 from a source 42. In intermediate positions of the valve 36, when applied pressure has moved both pistons out against springs 41, both cylinders are connected to exhaust through a port 37c. When the engine is running, the cylinders are connected alternately to pressure and exhaust but the pistons remain out and the pipe 33 remains connected to exhaust.. When the engine stops, pressure in the pipe 33 moves the piston unit 34 of an end-of-stroke indicator into position for actuation by a cam 43 connected by a link 29, lever 20 and link 21 to the synchronizing link 7. Pressure in the pipe 33 also acts on the piston 30 of the barring relay 32 and. admits pressure through the pipe 26, to open the relief valves 27 and actuate the barring piston 24, a groove on the stem of which connects the pipe 46 through a pipe 48 to a starting relay 49 Fig. 2. To effect starting, fluid pressure is applied through a pipe 75 to the relay 49, the piston 50 of which admits pressure from the pipe 48 to the cylinder 55 of a servo-motor actuating a master starting valve 59. This admits starting air from a source 61 through a pipe 62, timing valve 64 and the pipes 23 leading to the buffer cylinders 3. The valve 64 has three positions, closed, open, and fully released, and is biassed by a spring 63 to its fully released position. It is actuated through a lever 66 pivoted upon a lug 67 and provided with a trigger 68 pivoted on the lever and normally bearing on the valve stem. The lever 66 is biassed by gravity to a position in which the trigger 68 abuts against the valve stem. Air entering the valve body 63 from pipe 62 moves the valve to the open position, admitting air to the pipe 23. A collar 64b on the valve stem serves to delay the building up of pressure in the pipe 23, so accelerating the opening of the valve while delaying the building up of air pressure in the buffer cylinders 3. When the lever 66 is arrested by a stop, the trigger 68 comes into the path of the cam 43 actuated from the free pistons. As these pass a certain point the trigger is turned to release the valve 64, allowing it to move to closed position and to hold the trigger out of the path of the cam 43, so that the starting air supply is cut off. Subsequent closure of the master valve 59 allows the spring 63 to return the valve 64 &c., to initial position. The engine-is stopped by moving the fuel rack 10a of the pump 10 to cut off fuel; the rack is actuated through a lever 72 from a piston 69 on the admission of fluid pressure to a pipe 74. In modifications, (a) each buffer cylinder is fitted with an additional relief valve opening at a pressure above the normal buffer pressure: the exhaust from this valve may act through servo means to close the timing valve 64, dispensing with the trigger 68; (b) one of the compressor cylinders 2 is used for starting, the valve 13 being temporarily held closed ; (c) the fuel rack 10a is adjusted for controlling the fuel supply by the stopping relay 70 or a separate relay overridden by the relay 70 for stopping; (d) the indicator 35, barring relay 32, and valves 59, 64 may be mounted in one unit ; (e) the supply of pressure fluid to the barring cylinder 25 is controlled by electromagnetically operated valves responsive to electric signals from the running indicator, which may be a centrifugal or other mechanical device or an electrical device. The starting relay may also be electromagnetically operated.