Development of a Novel Uniflow-Scavenged Two-Stroke GDI Engine

This paper reports on the progress in the development and testing of a novel two-stroke gasoline direct-injection engine (GDI) that incorporates uniflow scavenging without the use of camshaft actuated poppet valves. Compressed air is fed into the cylinder through a matrix of passive check valves located in the cylinder head. Air-only scavenging, in combination with high-pressure GDI, ensures that traditional two-stroke pitfalls, such as high emissions and poor fuel economy due to short circuiting, are eliminated. The engine was successfully operated at speeds up to 5500 rpm. In-cylinder and intake plenum pressures were measured as a function of time and crank angle from which the check valve opening and closing time and the duration of the scavenging process was identified. The delivery ratio and air-fuel (A/F) ratio are reported.