VARIABLE VALVE SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To solve a problem of remarkable lowering of engine stability due to biting of a foreign matter at the time when a spool 40 returns to its initial position. SOLUTION: This variable valve system has a variable valve mechanism 10 to change opening and closing timing of a suction valve (or exhaust valve) in accordance with supply hydraulic pressure of hydraulic oil, a hydraulic pressure control valve 12 to regulate the supply hydraulic pressure in accordance with a working state of the spool 40 and a control part 14 to duty-control a solenoid 44 to drive the spool 40. Foreign matter removal motion to temporarily and reciprocatively move the spool 40 is carried out so as to remove the foreign matter in the hydraulic pressure control valve 12 in the case of judging that the spool 40 is in a returning state to start movement toward the initial position on the right side of a drawing.