MALFUNCTION DETECTION METHOD FOR ELECTROMAGNETICALLY DRIVEN INTAKE AND EXHAUST VALVE

摘要

PROBLEM TO BE SOLVED: To accurately detect a malfunction in valve motion based on a variation in current of one coil clue to a change in inductance thereof resulted from the selective shift of a plunger integral with a valve element from its position drawn in and held by the one coil to the other position held by the other coil. SOLUTION: Energizing an upper coil 24 generates electromagnetic force to displace a plunger 16 upward while energizing a lower coil 25 generates electromagnetic force to displace the plunger 16 downward. The plunger 16 thus vertically reciprocates to drive a valve element 10 in its opened or closed direction alternately. For detecting a malfunction of such an electromagnetically driven intake and exhaust valve, a current flowing in the one coil 24 is detected which is due to a change in inductance of the one coil 24 resulted from the selective shift of the plunger from the position held by the upper coil 24 to the position held by the lower coil 25 and the detected parameter is compared with a predetermined threshold value to determine whether a malfunction is present or not in the motion of the electromagnetically driven valve.