VARIABLE VALVE SYSTEM FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a variable valve system capable of varying the operating angle and the central phase of an intake valve 12 according to the operation state of an engine even when a potentiometer (an actual operating angle detecting means) 53 is in abnormality. SOLUTION: The variable valve system comprises an operating angle varying mechanism 10 capable of varying the operating angle of an intake valve 12; and a phase varying mechanism 70 capable of varying the central phase of the operating angle. Based on the rotation angle of a control shaft 16 detected by the potentiometer 53, a real operating angle is calculated and normality and abnormality of the potentiometer 53 are decided. During normality, feedback of the operating angle to a target operating angle is effected based on a real operating angle. During abnormality, open loop control of the operating angle to either a maximum operating angle or a minimum operating angle is effected based on an engine operation state.