Patent GB-190809612-A (GB)
Title: Improvements in Apparatus for Transmitting Power by Compressed Air.
Inventor: DUNLOP JAMES
Filed: 1908-05-04
Granted: 1909-05-03
Abstract: 9612. Dunlop, J. May 4. Compressed-air engines; gas and like engines.- Apparatus for transmitting power by means of compressed air, of the kind in which an air-compressor and a compressed-air engine are connected together in a closed circuit and air is normally maintained therein at a considerable pressure, is designed so as to enable internal - combustion engines or other prime-movers to be used more efficiently for variable and intermittent work such as the driving of locomotives or rolling-mills, or the propulsion of ships. To this end, the compressed-air engine is constructed so as to work with little or no expansion, and the speed or power developed by it is varied according - to requirements by providing the compressor with valve-actuating mechanism which is adapted to regulate the degree of compression in accordance with the demands of the compressed-air engine. The internal-combustion engine A is preferably made integral with the compressor B, the cylinders being fitted with a stepped piston so that the working strokes in the respective cylinders occur in opposite directions. The compressor and compressed-air engine, the latter represented only by its piston slide-valve and valve gear L, M, N, 0, P, form a closed circuit which does not contain an airstorage reservoir. The valve-actuating mechanism of the compressed-air engine is adapted to permit the engine to run in either direction but always with a constant admission period. For this purpose a radial valve gear or a link-motion valve gear is employed in which the reversing-link N presents a convex surface to the valve connecting- rod P. At mid-gear the piston slide-valve L is displaced so that one end of the cylinder is continuously open to admission and the other is continuously open to exhaust, which stops the engine. Such displacement of the valve L is adapted to cause a projection q to open the valve Q of a bypass leading from the delivery to the suction side of the compressor. The variation of the speed and power of the engine is effected by altering the travel of the piston distributing-valve C of the compressor whereby the suction and delivery takes place during varying periods of the strokes. For this purpose, the valve-actuating eccentric J, which rotates at the same speed as the driving-shaft, is provided with a cam-like strap h<1> operated from a control shaft k. The compressed - air passes through a surface heater R traversed on the other side by the exhaust from the prime-mover A. The exhaust from the compressed-air engine is water-cooled in a surface cooler S before returning to the compressor. The system is initially charged by the compressor by placing the valveactuating mechanism of the compressed-air engine at mid-gear, closing a valve T, and opening a valve U. Combustion and compression may be effected on opposite sides of a piston working in a simple cylinder. The valve-actuating mechanism may be adapted to control either the inlet or the outlet valves of the compressor in cases where they operate independently of each other.