Patent GB-612479-A (GB)
Title: Improvements in and relating to starting devices for free piston type internal combustion engine compressors or gas generators
IPC: F02B71/02
Filed: 1946-05-24
Abstract: 612,479. Free-piston compressors or gas generators; starting. ENGLISH ELECTRIC CO., Ltd., WELSH, R. J., and COX, G. W. May 24, 1946, No. 15875. Addition to 595,670. [Classes 7 (i) and 7 (v)] The invention relates to a free piston compressor or gas generator comprising a starting device which automatically acts to admit compressed air or gas in a number of pulses into a cylinder of the compressor or gas generator. A valve is provided between a source of compressed air or gas and the cylinder, which valve in a rest position is kept open by its own weight but is closed by the onrush of a compressed air or gas and temporarily opened by connection with the free piston assembly. Fuel is injected into the engine cylinder during the period of admitting starting air and while the stroke of the free piston assembly is increasing towards maximum amplitude of stroke. Fig. 1 shows a free piston gas generator fitted with the starting device. Compressed air from a source is admitted to a pipe 5 by a suitable control valve and passes to a starting regulator 4. Fig. 4 shows this regulator in part section. The valve 3 is originally held open under its own weight, but the compressed air forces it against its seat as shown. Before the valve closes, a small quantity of compressed air passes to pipes 6a, 6b and flows into cushion cylinders 103 and moves free piston assemblies 104-106 towards the centre of the engine. The movement of the assemblies through a synchronizing linkage 107, 108 and linkage A operates a cam 1 of the starting regulator and this opens valve 3 momentarily so that a pulse of compressed air passes to the cushion cylinders and gives the free piston assemblies an initial stroke. When the assemblies return near to the outer deadcentre position, either under the compression pressure in the engine cylinder or under the power of the engine if the engine fires the valve 3 is again opened and another pulse of compressed air is supplied to the cushion cylinders. By successive pulses the engine is operated until it is firing regularly. For moving the free piston assemblies to or near the outer dead-centre position ready for starting a barring piston 24 is employed. Fluid pressure is supplied through a running indicator 37 from a pipe 42 to a pipe 33 feeding a barring relay 32 and an end of stroke indicator 35. This fluid moves a piston 34 to the right, thus releasing fluid at the right of a piston 31 and allowing this piston 31 and a further piston 30 attached to it also to move to the right and thus allow fluid to pass to the barring cylinder 25. At the same time air release valves 27 in the cushion cylinders are opened, thus moving the free piston assemblies into the starting position. Fig. 2 shows a valve for supplying air to the pipe 5 from a pipe 61. When a piston 50 is moved to the left either by fluid pressure supplied at 75 or by a force applied to a member 50a, fluid pressure from a pipe 48 which pipe is supplied via the running indicator 37 pipe 33, end of stroke indicator 35 pipe 46, and an orifice 24a in the rod of piston 24 passes through pipe 54 and non-return valve 66 to operate pistons 56, 57 and open valve 10. The end of stroke indicator cuts off the supply of fluid to the pipe 33 when the free piston assemblies are operating, but the valve 10 does not close immediately, since the non-return valve 66 closes and fluid from the piston 56 can only slowly leak away through a byepass 67.