Valve timing control apparatus with a disallowing means

摘要

A valve timing control apparatus that continuously controls the valve timing of an intake valve or an exhaust valve of an engine. This apparatus includes a hydraulic variable valve timing mechanism, a hydraulic control valve and an electronic control unit for controlling the control valve. The variable valve timing mechanism alters the valve timing to change the valve overlap of the intake valve with respect to the exhaust valve. The hydraulic control valve controls the hydraulic pressure supplied to the variable valve timing mechanism. The real phase of the valve timing is coincided with a target phase that corresponds with the running conditions of the engine. When the real phase of the valve timing approaches the target phase, the hydraulic control valve is controlled to sustain the phase of that instant. The electronic control unit, which learns the control state of the valve-timing sustaining control, sets an initial learning value that reduces the valve overlap when the learning has started. A correction means is disallowed from computing a current specific value when the computed target value is within a predetermined range.