Patent GB-583412-A (GB)
Title: Internal-combustion-operated free-piston compressors and gas-generators
IPC: F02B71/00
Filed: 1942-02-12
Abstract: 583,412. Free-piston compressors and gas generators. MUNTZ & CO., Ltd., A., and MUNTZ, F. A. I. Feb. 12, 1942, No. 1903. [Classes 7 (i) and 7 (ii)] To overcome in a free-piston gas generator or compressor the inequalities in the piston stroke and thus in the compression ratio, due to varying loads,.controlled means are provided to vary the capacity of the combustion space by putting the combustion chamber into or out of communication with an auxiliary chamber which may be of variable volume. The gas generator shown in Fig. 1 has oppositely-moving working pistons 11A, 11B and pump pistons 20A, 20B the front faces of which deliver scavenging and charging air into a reservoir 14 which opens into the combustion cylinder through inlet ports 12. The spaces at the outer ends of the pumps serve as cushioning chambers. The movements of the pistons are synchronized by rods 25 and oscillating arms one of which is shown at 24<1>. Vertical arms 27A, 27B slide on guideways 28A, 28B and support the pistons. To vary the capacity of the main combustion space auxiliary chambers, one of which is shown at 30, are provided which open into the working cylinder through valve controlled ports 31. The coiitrolling valves 42 carry pistons 43 housed in cylinders 44 to which oil under pressure is supplied through pipes 46, 47. Springs 45 hold the valves in their closed positions the closihg pressure being supplemented by the oil supply through the pipes 46. The pressure in the pipes 46 is released when oil enters through the pipes 47 to open the valves. They open when the pressure in the working cylinder rises and close when the pressure falls. The oil supply is distributed by a valve 48, Fig. 7, controlled by a piston 50 which slides in a cylinder 51 in open communication with the air reservoir 14. The stem of the valve 48 is arrested in its two extreme positions by a spring-pressed ball 54 which enters recesses in the stem. Variation in the volume of the combustion space is accompanied by an alteration in the degree of cushioning in the pump cylinders. For this purpose the rod 61 of a gear (not shown) which regulates the air cushions is controlled by a tappet 62 having a lost-motion head 63 which engages the rod 61. The tappet is normally raised by a cam 59 mounted on the shaft 60 of the pistonsynchronizing mechanism but it is lifted by oil pressure in the pipe 70 when pressure is applied through the pipes 47 to open the valves 42. In an alternative construction, the capacity of each auxiliary clearance chamber may be adjusted by a piston 71, Fig. 8, which through a screw- and-nut connection is controlled by bevel gearing driven by a shaft 73. In the upper limiting position of the piston the fuel supply to the injectors is cut off by opening the fuel supply pipe 79.to a venting orifice controlled by a valve 31. Oil pressure on a piston carried by the valve holds the valve on its seat. A valve 83 which controls the oil supply is adjusted by a lever which bears at one end on the adjustable piston 71 and at its other end is connected to a piston subject to the air pressure in the reservoir 14. Specification 579,733 is referred to.