Denso Corporation

Minoru Wada

Yuichi Takemura

Yasuhiro Shikata

Haruyuki Urushihata

Masaomi Inoue

Yasuhiro Kajiwara

A VVT has a movable restriction member and a restriction slot. When the restriction member is in a projected position, the VVT is variable in a restricted range to which the restriction member can be rotatable within the restriction slot. When the restriction member is in a retracted position, the VVT is variable in a range wider than the restricted range. When a condition where the restriction member shall be projected is satisfied, if the variable range of the VVT reaches beyond the restricted range, the device determines that the restriction member is stuck at the retracted position. When a condition where the restriction member shall be retracted is satisfied, if the variable range of the VVT is restricted in the restricted range, the device determines that the restriction member is stuck at the projected position.

Variable valve timing device

A variable valve timing control apparatus adjusts the rotation phase (VCT phase) of an engine camshaft by selectively supplying oil to an advancement chamber and a retardation chamber, and includes a lock pin which is controlled for being moveable to a first position, in which the rotation phase is adjustable, and a second position, in which the camshaft is locked at a specific rotation phase. When the lock pin is displaced from the first position, oil becomes enabled to pass between the advancement chamber and retardation chamber, to thereby enabling the rotation phase to be changed to the specific rotation phase by supplying oil to an appropriate one of the advancement chamber and a retardation chamber, for initiating locking.

Variable valve timing control apparatus for internal combustion engine

A control device projects a lock pin to lock a VCT phase in an intermediate lock phase when a lock request occurs. A learning unit learns one of a most retarded phase, a most advanced phase, and an intermediate lock phase, as a reference phase. A control unit sets a target phase according to the reference phase and controls the control device. A monitor unit determines that the VCT phase has passed through the intermediate lock phase when the lock request occurs before completion of learning of the reference phase, and when a change in the VCT phase becomes greater than a threshold. The threshold is set to be greater than a sum of i) a design value of a phase difference between the intermediate lock phase and one of the most retarded phase and the most advanced phase and ii) a range of a product variation of the phase difference.

Variable valve timing control apparatus and method for controlling variable valve timing device

An engine valve control device is applied to an engine valve control mechanism having a VVT (valve timing adjusting device), an OCV (control valve) that controls a flow of hydraulic oil supplied to the VVT, and an electromagnetic solenoid that controls an operation of the OCV according to a control duty (control command value). The engine valve control device calculates the control duty based on a holding duty, which occurs when an actual phase does not change but is held, and feedback correction values. The engine valve control device corrects the value of the holding duty in accordance with a steady-state deviation between the actual phase and a target phase to perform learning for storing and updating the holding duty value. If temperature of the hydraulic oil is low, the learning is prohibited even when the steady-state deviation is occurring.

Engine valve control device

In a variable valve timing control apparatus, a hydraulic variable valve timing device adjusts valve timing by changing a VCT phase. In a lock mode, the lock pin is allowed to be displaced in a lock direction for locking the VCT phase, and the VCT phase is slightly shifted in a lock-mode VCT phase shift direction corresponding to one of an advance direction and a retard direction. A lock control unit shifts the VCT phase in a direction opposite from the VCT phase shift direction if the VCT phase is located on a lock-mode VCT phase shift direction side of the intermediate lock position when the engine becomes equal to or less than a first rotational speed, and otherwise the lock control unit allows the lock pin to be displaced in the lock direction.

When a valve timing is held, even if a Duty value of an operational signal of a variable valve timing controller is slightly changed, a holding unresponsive range will be arisen. In the unresponsive range, a variation speed of the valve timing is very small. As temperature is decreased, the unresponsive range is extended and an individual difference becomes notable. While the valve timing is held, a computer learns a deviation amount of a response characteristic of the valve timing based on a variation speed of the valve timing when the Duty value is slightly changed from the holding unresponsive range to outside thereof.

Valve characteristic controller and valve characteristic control system

A variable valve device modulates movement of a valve for an internal combustion engine by using hydraulic fluid pressure. The variable valve device is controlled by a control device via a control valve that modulates hydraulic fluid pressure supply to and discharge from the variable valve device. The control device offsets an operating amount of the control valve by an offset component that shifts the operating amount outside a dead band. The control device sets the offset component smaller as the hydraulic fluid temperature increases. The control device sets the offset component smaller when a controlling direction coincides with a biasing direction of a biasing member than that when the controlling direction opposes the biasing direction. Further, the control device cancels the offset component when actual valve movement is sufficiently close to target valve movement.

Apparatus for controlling variable valve device

A valve timing control apparatus for a valve timing adjustment mechanism that adjusts timing of opening and closing an intake or exhaust valve of an engine includes an output-side rotor, a cam-side rotor, a hydraulic pump, a control device, a control valve, a storage device. The control device outputs a signal associated with rotation of one of the rotors relative to the other one. The control valve controls the speed of the rotation. The storage device prestores standard data indicating a predetermined relation between a dead zone width and a parameter correlated with the dead zone width for each hydraulic oil temperature. A value of the parameter of the adjustment mechanism during a hold state is learned by changing the signal. The control device computes the signal based on the value learned, the standard data, and hydraulic oil temperature.

Valve timing control apparatus and valve timing control arrangement

When a variable valve lift control apparatus is in a steady condition, a fluctuation control is performed. In the fluctuation control, a target lift amount is increased by a fluctuation width during an up-time and then the target lift amount is decreased by the fluctuation width during a down-time which is longer than the up-time to be returned to an original value. A decreasing amount of the integral term is greater than the increasing amount thereof. Consequently, the integral term can be made smaller than the original value. Even when a control duty is a larger value due to a hysteresis, the fluctuation control gradually decreases the increment of the integral term and converges the control duty to the small value.

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Obu, Japan

Minoru Wada