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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 mechanical fully variable valve lift system UniValve represents one of the new technical solutions for a throttle free load control for combustion engines. The load control is achieved by the variation of the valve lift and the simultaneous variation of the opening and closing time. The design of the system has as result a simple layout with a valve train component assembly that leads to a compact integration into conventional cylinder heads. In addition to the first results presented at the SAE Congress 2004 this paper provides the results of the fired engine and the valve train operation on the component test bench. Furthermore the potentials of the throttle free load control with the UniValve system in comparison to a conventional throttle engine operation with the same engine type are pointed out. Perspectives for the application in an four cylinder engine are given.