Improvements in and relating to internal combustion engines

815,030. Two-stroke engines; cooling and pumping charge; valves and valvegear. BROWN, BOVERI & CIE A. G. March 11, 1957, No. 7934/57. Classes 7(2) and 7(6) In a two-stroke diesel engine 1, Fig. 1, supplied with air by an exhaust-driven turbo-charger 6 and an auxiliary compressor 7 in parallel through ducts 11, 101, at starting, low load and, optionally, high load a valve 9 directs the compressor delivery to a nozzle 11 in the turbo-charger delivery and directed downstream thereof so as to prevent turbo-charger "pumping". Coolers 14, 141 and smoothing reservoirs 8, 4 are provided. The compressor 7 may be driven by an electric motor or a steam turbine at constant or adjustable speed, by a hydraulic or pneumatic motor or by the engine 1 or may be the underside of an engine piston acting as a pump. n Fig. 4 the nozzle 11 is in one limb 12" of a branched turbo-charger delivery 121, 12", valves K\ K2 and a valve K' in the compressor delivery 102 being in the positions shown at starting and low load, and the valves K1, K3 open and the valve K2 closed at high load. The valve 9 or valves K1-K3 may be operated manually, directly or by mechanical remote control, or automatically. In Fig. 5 (not shown) the nozzle 11 delivers to the supercharger volute; in Fig. 6 (not shown) from the reservoir 8 to the engine cylinder inlet port belt under valve control and during scavenging only; and in Fig. 7 (not shown) to the inlet port belt from a pumping space under the engine piston and discharge from which is controlled by a spring- closed valve opened by abutments with the engine piston.