Valve duration control system for four-cycle engine

摘要

The system controls a cam drive mechanism for an intake valve such that the associated cam maintains the valve duration of the timing of the intake valve at a short valve duration in response to shift from engine operation at low speed with low load to engine operation at low speed with high load, and such that the cam increases the valve duration of the intake valve to a long valve duration in response to shift from engine operation at low speed with low load to engine operation at low speed with medium load.