Toyota Jidosha Kabushiki Kaisha

Atsushi Yasumura

Senji Kato

Nobuhisa Ohkawa

Tadahisa Naganawa

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.

Valve timing control apparatus with a disallowing means

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 restricting means for restricting a correction means is included.

Valve timing control apparatus with a restricting means

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. An initializing means is added for initializing a current specific value when a recondition after a malfunction is determined.

Valve timing control apparatus with an initializing means

A valve timing control apparatus that adjusts valve overlap by altering valve timing according to the running condition of the engine. A variable valve timing mechanism (VVT) alters the valve timing of intake valves to adjust the valve overlap. An electronic control unit (ECU) controls the VVT with respect to a target value calculated in accordance to the running condition of the engine to obtain the optimum valve overlap. The ECU controls the VVT to eliminate valve overlap under low temperature conditions. The ECU controls the VVT to switch from a state of nonexistent valve overlap to a valve overlap state as the temperature changes from a low temperature to a higher temperature. The ECU judges whether the engine is in a low temperature condition based on a predetermined reference value to suppress the difference in the amount of fuel (port wet amount) adhered to the intake port before and after the shifting of the state the valve overlap.

Valve timing control apparatus for engine

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.

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Toyota, Japan

Atsushi Yasumura