Development of Variable Cylinder Management System for Large Motorcycles- An Effective Way of Reducing Output Change at Switching of the Number of Working Cylinders

The world's first Variable Cylinder Management (VCM) system for large motorcycles, which will achieve both high power and low fuel consumption, has been developed. The system uses a mass production in-line four-cylinder engine which has a displacement of 1137 cm₃ as the base engine. The VCM system is capable of increasing and decreasing the number of working cylinders between 2-cylinder, 3-cylinder and 4-cylinder operations by modifying some parts of the base engine. Utilizing throttle valves installed on each cylinder, the throttle valves for continuously operating the regularly working cylinders and the on-demand working cylinders are controlled by three motors, which divide them into three independent lines. In order to improve fuel consumption by reducing the pumping loss of the non-working cylinders, the engine is equipped with hydraulically operated intake and exhaust valve deactivating mechanisms. It is very important for the posture control of the moving motorcycle to prevent abrupt changes of engine power output when the number of working cylinders is changed. In order to prevent such abrupt changes, the newly developed VCM system controls engine power output using the harmonized control of the three-system-independent Throttle-by-Wire (TBW) and the intake and exhaust valve deactivating system. Also, the fuel consumption in New European Driving Cycle (NEDC) mode is improved by approximately 46% as compared with the base motorcycle while clearing the EURO3 exhaust emission regulation values. Power output characteristics equivalent to those of the base engine are achieved. In this paper, the outline of the VCM system, the effective way of reducing output change when switching the number of working cylinders, and the effects of the improvement in fuel consumption are described.