GB551304A - Improvements relating to pressure gas generating machines, and particularly to free piston machines - Google Patents

Abstract

551,304. Free-piston compressors. PESCARA, R. P. June 27, 1940, No. 10984. Convention date, June 29, 1939. [Class 8 (i)] [Also in Group XXVII] In a two-stroke motive-gas generator or air compressor of the free piston type having air compressing cylinders and a power cylinder to which fuel and air are supplied, the generator or compressor is operated in such a manner that one or more active cycles of the free piston assembly alternate with one or more neutral cycles of such a stroke length that the scavenge and exhaust ports of the power cylinder are only slightly opened or not opened so that scavenging is incomplete or does not occur, the delivery of air by the compressor piston being reduced or ceasing during the neutral cycles. Fig. 1 shows a free piston gas generator for driving a turbine T, having air compressor pistons 5<SP>1</SP>, 5<SP>1</SP> operating in cylinders 6<SP>1</SP> 6<SP>2</SP> and pistons 1<SP>1</SP>. 1<SP>2</SP> operating in the power cylinder 2 provided with an air inlet port 3 and exhaust port 4 connected through a pipe 16 with the turbine. Fuel injectors 12, 32 are provided and air compressed by the pistons 5<SP>1</SP>, 5<SP>2</SP> during their outward strokes passes to a chamber 11 and enters the cylinder 2 through the port 3 for combustion and scavenging purposes. A cam 14 attached to and moving with the pistons actuates a main fuel supply pump 13 supplying the injector 12 and a pump supplying a small quantity of fuel to the injector 32. The neutral strokes are provided at low outputs by shutting off the fuel supply to the injector 12 automatically in accordance with the pressure in the gas delivery pipe 16. This pressure is communicated to a spring-loaded piston 22 in a cylinder 23. As the pressure falls the piston displaces through a lever 21 a rotary cam 19 having cam surfaces which engage the spindle 18 of a spring- loaded valve 17. During the closure of the valve fuel flows from the pump to the injector and all the strokes of the generator are active. When the valve is opened by the cam the fuel escapes through the valve and neutral strokes occur, the duration of the active and neutral strokes depending on the shape of the cam. The injector 32 supplies a small quantity of fuel to the power cylinder during neutral cycles. The fuel supply pump is controlled during higher output of the generator by the turbine governor through a rod 25 and member 15, the working range of the rod 25 being controlled by an abutment member 26, 27 pivoted to the lever system 21. Fig. 2 shows a compressor in which the air compressor cylinders 6<SP>1</SP>, 6<SP>2</SP> discharge into a reservoir 33 and also into the chamber 11 surrounding the power cylinder, the air pressure being utilized to control the active and neutral cycles.