VAVACT-Variable Valve Actuation Mechanism

When using variable valve actuation mechanisms, accuracy of varying the valve lift and timing at varying engine rotation speeds, loads and temperatures is extremely important when aiming for balanced operation, valve throttling and possible valve deactivation of multi-cylinder engines. Also some wear of the mechanism should not significantly decrease this accuracy of operation. Further the mechanism ought to be compact, and installation of the mechanism should be possible without any initial manual adjusting. In this paper some means are presented, by which the control ramp mechanism, presented previously in the SAE Paper 980768 [1], could be made more compact and by which lower frictional losses and more accurate functioning of this self-adjusting VAVACT-mechanism may be achieved.