Patent GB-423777-A (GB)
Title: Improved method of and apparatus for starting free piston internal combustion engines for operating compressors
IPC: F01L13/00
Filed: 1934-05-23
Abstract: 423,777. Starting. JUNKERS, H., 21, Hauptmann Loeper Platz, Dessau, Anhalt, Germany. May 23, 1934, No. 15423. Convention date, May 23, 1933. [Class 7 (v)] Free - piston internal - combustion engines operating as compressors are started by energy absorbing and delivery means, the amount of energy absorbed and delivered by which is gradually reduced at approximately the same rate as the load on the engine and compressor is increased to normal working conditions. The energy accumulator may be in the form of springs, rubber cords, falling or swinging weights, or pistons acted on by gas or liquid pressure or the explosion of a gunpowder cartridge. Fig. 1 shows opposed internal-combustion pistons 1 operating in a cylinder 11 with inlet and exhaust ports 4, 5, and connected to compressor pistons 2 operating in cylinders 12 with inlet and discharge valves 7, 8. These are further connected to starting pistons 3 working in cylinders 13 to which compressed air is supplied through conduits 21. The two sets of pistons are coupled together by racks 14, 14<1> engaging a pinion 15 and are held in position ready for starting by a catch 18. When the starting-air is admitted to the cylinders 13 and the catch 18 released, the pistons 3 are actuated to compress the air charge in the internal-combustion cylinder, into which fuel is injected at 16. As the pistons 3 near the end of their stroke, a port 25 is uncovered so as to admit the compressed air to pistons 26 which actuate valves 27 to close the admission from the conduits 21. When ignition occurs, the return of the pistons is facilitated by removing the load on the compressor pistons 2, this being effected by a valve 32 which is arranged in the discharge conduit 30, 31 and is held open by the action of the starting-air on a piston 35 exposed thereto through a conduit 36 connected to a chamber 20, to which the air in the cylinder 13 has access by means of a small orifice 37. A valve, (not shown), in the pipe 31 is opened during the starting operations to relieve the compressor pistons from load. The return movement of the pistons again compresses the air in the cylinders 13, which in turn produces another inward movement of the pistons. As starting proceeds, the energy stored in the accumulator is gradually reduced by slowly opening discharge valves 39, and as this is reduced the pressure on the pistons 35 is correspondingly lessened, so as to bring about a gradual closing of the valve 32, and thereby a proportionate increase of the load on the compressor and engine pistons. When normal working conditions are attained, the pressure on the piston 35 ceases, and the valve 32 is opened by the pressure acting on the valve head, the compressed air being then delivered through the pipe 31. The starting-air pressure may also act on a piston 44 connected to a compressionrelief valve 41 for the combustion space, which is thus also gradually closed as starting proceeds. In a modification, the chamber 20 is replaced by a similar vessel provided in the conduit 30, so that the compressors 2 gradually build up pressure therein which acts to close the valve 32 and also to close the discharge valve 39 ; also this pressure may be used to act on the fuel-pump drive so as to give a gradual increase in the amount of fuel supplied. Fig. 3 shows a starting-device employing springs 71 which act through a cam-shaped lever 65 to rotate a shaft 64, which may be clutched to the pinion 15, Fig. 1. For starting, the shaft of the pinion 15 is turned by a crank handle so as to compress the springs 71. The catch 18, Fig. 1, is then released so that the springs give a starting movement to the pistons, the resulting ignition causing the springs to be compressed again. The energy stored in the springs is gradually reduced by movement of the casing 70 by means of a hand lever 74, thereby reducing the leverage of the cam faces 67, the valve 32 being simultaneously gradually closed by linkage 81, 82, 83. The casing 70 may be actuated by the pressure produced by the compressor, instead of by hand.