Patent GB-605195-A (GB)
Title: Improvements in free-piston compressors and gas-generators of the opposed-piston type
IPC: F02B71/00
Filed: 1945-07-03
Abstract: 605,195. Starting free-piston compressors or gas generators. PESCARA, R. P. July 3, 1945, Nos. 16962 and 16963. Convention dates, May 30, 1944, and Aug. 5, 1944. [Classes 7 (i) and 7 (v)] In an internal-combustion operated free-piston compressor or gas generator in which opposed free-piston assemblies each co-operate with a starting chamber into which gas under pressure can be admitted from a starting device, the starting device comprising a starting valve the opening of which suddenly releases a charge of compressed gas into the starting chamber, so that the free piston assemblies are accelerated from starting positions towards their inner dead points, the starting chambers are interconnected permanently by means of an open balance duct, the starting device opens into the duct and the flow area of the duct is so large that pressures existing at any instant in the starting chambers are substantially the same. The Figure shows a gas generator having opposed pistons 2‹, 2‹‹, operating in a common working cylinder 1. Compressor pistons 5‹, 5‹‹ are attached to the pistons 1 and between the outer faces of the compressor pistons and the compressor cylinders are formed pneumatic energy accumulators A‹, A‹‹. These accumulators form starting chambers into which gas under pressure is admitted through a duct 23 which permanently interconnects the accumulators. The compressors deliver air into an enclosed space around the engine cylinders. The gas under pressure is introduced into the duct 23 from a starting device comprising a valve 10, with an integral piston 12 and a reservoir 11. A cock 15 connected to a source of compressed gas in one position I enables the gas to pass to a space 14 above the piston and so holds the valve closed and through a duct 18 in the piston to charge the reservoir 11. In another position III of the cock, the gas from the space 14 escapes to atmosphere and the piston then opens the valve and the gas in the reservoir flows through the pipe 23 to the accumulators. A duct 20 and non-return valve 21 are arranged to connect the accumulators to the space 14 so that during normal operation the pressure of gas in the accumulators is applied to the piston 12 and keeps the valve 10 closed. Also gas from the accumulators can pass through the duct 18 and keep the reservoir 11 charged. An arrangement similar to that described in Specification 556,454 is provided to control the pressure in the accumulators. This comprises a control valve 25 and piston 29 carried in one assembly with the starting valve 10. The valve 25 controls the pressure in the accumulators in accordance with the pressure of the compressed air supplied to the interior of the casing. Pressure in this casing operates on the top of piston 29 and the pressure in the accumulators operates on the lower surface of the piston so that as these pressures vary so the valve 25 is moved and admits air to or releases it from the accumulators through the pipe 23. A valve 34 is provided to release the air in the accumulators so that the engine pistons can be brought into the required position for starting. In a modification (not shown) the starting valve is mounted in a casing fixed to the end cover of one of the accumulators. The area of the passage connecting the valve with the accumulator at that end is smaller than that of the duct 23 so that substantially the same pressure drop occurs between each accumulator and the valve. Specifications 605,199 and 605,202 also are referred to.