Patent GB-721025-A (GB)
Title: Improvements in or relating to internal-combustion engines
IPC: F02B3/06
Filed: 1953-07-09
Abstract: 721,025. Changing the system of working; starting ; carburetters. SMITH, J. H. July 9, 1953, No. 19032/53. Classes 7 (2), 7 (3) and 7(5). In an engine comprising at least one pair of parallel cylinders of different diameters and communicating with each other by a valveless passage 18 and wherein the smaller cylinder and piston 14 act as a compressor for supplying fuel diluted with the cooled combustion products of the engine through the passage 18 for combustion with air compressed in the larger cylinder, the air and combustion products are supplied through ducts 19, 23 which are automatically controlled by throttle valves 27 interconnected, e.g. by a link 30, to move in unison, and the fuel drawn from a fuel-metering device 31 is induced by the flow of combustion products into the duct 23 in a position downstream of the valve of the duct and when the valve is open so that the engine operates as a compression-ignition engine. The duct 23 has an air inlet 34 intermediate the associated valve 27 and the fuel injection position so that when both the valves 27 are closed and the engine is to be started or run at an idling speed, all the air for combustion is drawn through the inlet 34, and the engine by means of a sparking device 35 in the larger cylinder then functions as a spark-ignition engine, the circuit of the device 35 being energized only when the valves 27 are closed. The pistons 13, 14 are operatively interconnected so that the larger piston 13 leads the smaller piston 14, e.g. the crankpins 15, 16 may be spaced apart by an angle of about 30 degrees. Each cylinder has inlet and exhaust ports controlled by valves 21, 24 and 22, 25 which may be operated by a camshaft driven from the crankshaft 17. The device 31 may comprise a chamber 45 and a diaphragm 47 on which the pressure of the fuel in the chamber act to close a valve 44 in opposition to a spring 48 the effort of which can be varied by a bellcrank lever 37, 38 connected to a rod 36 reciprocated by movement of an engine accelerator control. As the fuel is consumed the restraint on the movement of the diaphragm 47 is reduced to allow the spring 48 to open the valve 44, and an outlet passage 46 for the fuel is controlled by a spring-loaded valve 49 opened by a control 50 operated by a governor dependent upon the engine load, the passage 46 being connected by a pipe 32 to a jet in the duct 23. The depression over the jet may be communicated through a pressure-balancing pipe 33 to the top of the diaphragm 47. To, ensure vaporization of the fuel the pipe 32 may pass through an electrically-heated muff. Abutments 42 carrying insulated contacts, or some other form of switch, may be mounted on the link 30 and the rod 36 and are engaged to energize the circuit of the sparking device 35 when the valves 27 are operated to the closing direction. In an alternative form, Fig. 4 (not shown), the device 31 comprises a float chamber connected by the pipe 32 to the duct 23 which is controlled by a needle-valve biased by a spring against the operation of the bell-crank lever 37, 38 and passing through the throat of a Venturi.