The targets for future gasoline engines in terms of fuel consumption and exhaust gas emissions require the introduction of advanced technologies to increase engine efficiency.
The mechanically fully-variable valve train system UniValve is an effective device to reduce fuel consumption through throttle-free load control. This is achieved by the simultaneous variation of valve lift and valve opening event. The method of cylinder deactivation by closing the gas exchange valves is a further approach to increase the efficiency of combustion engines especially at part load.
This paper presents the combination of both techniques on a downsized, turbo charged 4-cylinder DI gasoline engine. The mechanical integration of the valve shut-off capability for cylinder deactivation into the Univalve system is explained and strategies for the transition between 2-cylinder and 4-cylinder modus are discussed. The thermodynamic benefits through adoption of both technologies are analyzed and a reasonable application area of cylinder deactivation in the engine operation map is pointed out. In the conclusion, the achievable fuel consumption benefits will be presented.
