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Different mechanisms for Continuously Variable Valve Lift (CVVL) have been proposed and patented and partially implemented in mass production. The objective of this paper is to review the functional appeal of one possible solution, comprising the valve train itself and the control mechanism. This paper describes the operating principle of the valve train and the control mechanism and also shows examples for different arrangements to allow for various cylinder head architectures. The current state of development is outlined and an application on a modern inline four-cylinder engine is presented. Results of experimental investigations are shown to evaluate the functionality of the system. The potential of load control by means of Early Intake Valve Closing is discussed on the base of fired engine test bench results.

Modern passenger car engines are designed to operate at increasingly higher rated engine speeds with more internal parts (multi-valve engines) requiring lubrication. The paper presents results of research and development activities to reduce the actual feed rate of the oil consumers to their real requirements depending on the most significant influence parameters. Based on these results an optimization strategy is presented which combines CAE tools with data from experimental work. In the conclusion of the paper recommendations are summarized to show the optimization potential of actual lubrication and ventilation systems concerning design. power input respectively oil consumption.

Fuel consumption of a modern combustion engine is significantly influenced by the mechanical friction losses. Particularly in typical city driving, the reduction of the engine friction losses offers a remarkable potential in emission and fuel consumption reduction. The analysis of the engine friction distribution of modern engines shows that the piston group has a high share at total engine friction. This offers a high potential to optimize piston group friction. The paper presents results of recent research and development work in the field of the tribological system piston/piston ring/cylinder bore.