Valve timing control apparatus with an initializing means

A valve timing control apparatus for an engine having an air intake passage for introducing air to a combustion chamber and an air exhausting passage for exhausting gas from the combustion chamber, said intake passage and said exhausting passage having an intake valve and an exhaust valve, respectively, the valves being alternately opened and closed with a valve timing according to rotation of a cam shaft, which rotates in synchronism with rotation of a crank shaft of the engine, and wherein the valves are simultaneously opened during a period of valve overlap, and wherein the rotational phase of the cam shaft is arranged to be selectively advanced or retarded with respect to the rotational phase of the crank shaft to converge the valve timing to a target value so as to vary the period of the valve overlap within a range between a maximum value and a minimum value based on a current running condition of the engine, said apparatus comprising:

• adjusting means for continuously adjusting the valve timing of at least one of the intake valve and the exhaust valve, said adjusting means being driven by hydraulic pressure;
• supplying means for supplying the hydraulic pressure to said adjusting means, said supplying means including tuning means for tuning the hydraulic pressure;
• first detecting means for detecting the running condition of the engine;
• computing means for computing the target value based on said running condition;
• second detecting means for detecting the actual valve timing adjusted by the adjusting means;
• control means for controlling the supplying means to operate the adjusting means so as to converge the detected valve timing to the target value and vary the period of the valve overlap based on the running condition of the engine, wherein said control means controls the supplying means to sustain the valve timing where it is approximately coincided with the target value;
• first determining means for determining an offset between the detected valve timing and the target value when the valve timing is sustained by said control means for a predetermined time period, said first determining means including calculating means for calculating an offset value between the valve timing and the target value;
• correction means for correcting said target value with a current specific value for cancelling the offset value, said correction means being arranged to compute the current specific value based on said offset value;
• second determining means for determining, based on the detected valve timing, a malfunction of the adjusting means or the supplying means such that the valve timing is kept constant;
• third determining means for determining, based on the detected valve timing, reconditioning of the adjusting means or the supplying means after said malfunction;
• and
• initializing means for initializing said current specific value when the recondition after the malfunction is determined, wherein the current specific value is changed to a predetermined value when initialized.