INVESTIGATION OF THE INFLUENCE OF MANUFACTURING TOLERANCES ON A FULLY VARIABLE VALVE TRAIN

摘要

Different mechanisms for Continuously Variable Valve Lift (CVVL) have been proposed and patented and partially implemented in mass production. This paper briefly reviews the functional appeal of one solution called INA EcoValve. To the authors’ knowledge very little attention has been paid to understand how manufacturing tolerances influence the overall functional behaviour of high-speed mechanisms and in particular to continuously variable valve trains. Therefore the specific requirement arising from these kinds of valve trains are discussed. The shortcomings of traditional tolerance analysis methods are outlined and it is shown, that the inclusion of clearances and flexible parts is fundamental for the full understanding of the influence of tolerances on the valve train performance. A strategy is proposed that will allow the influence of tolerances on the dynamic behaviour of the valve to be understood. Through this understanding optimal valve trains can be manufactured to meet both cost and performance objectives.