Abstract: A variable valve system including a crank angle sensor that measures a rotation angle of a crankshaft, a cam angle sensor that measures a rotation angle of a camshaft coupled to the crankshaft and which opens and closes valves, and a controller that controls the internal combustion engine. At least one of the crank angle sensor or the cam angle sensor is configured as an absolute angle sensor that measures an absolute rotation angle and outputs a voltage signal corresponding to this rotation angle. The controller is configured to perform a correction operation that corrects a rotation angle value calculated based on the voltage signal.

Abstract: When a variable valve timing device controls an oil pressure control valve in a manner that a VCT phase is locked at a middle lock phase, an advance chamber and a retard chamber are made to communicate with each other, so that oil is filled into both of the advance chamber and the retard chamber when the oil pressure control valve supplies oil to one of the advance chamber and the retard chamber in an oil filling mode. An oil pump supplies oil to the oil pressure control valve, and is controlled to have an oil flow rate that is equal to or larger than a predetermined value in the oil filling mode.

Abstract: A variable valve system including a crank angle sensor that measures a rotation angle of a crankshaft, a cam angle sensor that measures a rotation angle of a camshaft coupled to the crankshaft and which opens and closes valves, and a controller that controls the internal combustion engine. At least one of the crank angle sensor or the cam angle sensor is configured as an absolute angle sensor that measures an absolute rotation angle and outputs a voltage signal corresponding to this rotation angle. The controller is configured to perform a correction operation that corrects a rotation angle value calculated based on the voltage signal.

Abstract: A variable valve timing control apparatus includes an abnormality determining portion and a valve controller. The abnormality determining portion determines whether there is an abnormality in a system of a VCT phase control in which an oil pressure control valve is controlled in a manner that an actual VCT phase coincides with a target phase. The valve controller controls the oil pressure control valve to drive a lock pin in a locking direction so as to lock the VCT phase when the abnormality determining portion determines that there is an abnormality in the system of the VCT phase control.

Abstract: 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.

Abstract: A valve timing control apparatus for a valve timing adjusting unit that adjusts valve timing of an engine. The control apparatus learns a reference position. The control apparatus computes an actual phase based on the learned reference position. The control apparatus computes a target phase based on an engine operational state. The control apparatus controls a hydraulic actuator to perform a phase control based on a difference between the target phase and the actual phase. The control apparatus determines whether the lock mechanism is under an abnormal state. When the control apparatus determines that the lock mechanism is under the abnormal state, the control apparatus is prohibited from performing the phase control that uses the reference position.

Abstract: A valve timing adjuster includes a first rotor, a second rotor, a control valve, and a lock mechanism. The lock mechanism includes a retard limitation pin and an advance limitation pin, each of which is provided to the second rotor. The lock mechanism includes a retard limitation groove and an advance limitation groove, each of which is formed to the first rotor. The retard limitation groove and the advance limitation groove are designed to limit the displacement of the retard limitation pin in the retard direction and simultaneously limit the displacement of the advance limitation pin in the advance direction in order to lock the first rotor and the second rotor. The valve timing adjuster alternately increases the oil pressure in the retard chamber and the oil pressure in the advance chamber when the lock of the first and second rotors is released.

Abstract: An ECU executes a program including the steps of: detecting engine speed NE (S100); and stopping power supply to an electric motor of an intake VVT mechanism (S104), if engine speed NE is equal to or lower than a threshold value NE (0) (YES at S102).

Abstract: In valve timing control after issuance of an engine stop instruction with a prescribed value set as a target phase, an ECU delays permission of an engine stop process within a prescribed time period while an intake valve phase has not yet reached the target value, so that a valve timing control operation is continued while the engine operation is continued in an idle state. After the lapse of a prescribed time period from the issuance of the engine stop instruction, however, the ECU permits the engine stop process no matter whether the intake valve phase has reached the target value or not. As a result, the amount of valve timing that can be changed by the valve timing control in the engine stop operation can be increased, without causing any uncomfortable feeling of the driver.

Abstract: If it is necessary to rapidly change a phase of an intake camshaft and an intake VVT mechanism relatively slow in responsiveness as it is associated with an “A” bank of a V-type, 8-cylinder engine is in operation for at least a predetermined period of time, an ECU executes a program including the step of controlling intake VVT mechanisms to operate those associated with both the “A” bank and a “B” bank.

Abstract: At the time of reference position learning for ensuring accuracy in detecting a valve timing, an operation amount of an actuator is set such that intake valve phase changes to a position of most retarded angle as a reference phase. When the intake valve phase reaches the most retarded angle and the change in the intake valve phase stops (YES at S150), it is determined that the intake valve phase has reached the reference phase and the learning is terminated normally. If the learning operation does not end normally even after the time lapse from the start of learning exceeds a limit time Tlmt, the reference position learning is terminated forcibly (YES at S170), and power supply to the actuator is stopped. Thus, power consumption can be reduced and the apparatus can be protected at the time of reference position learning.

Abstract: An ECU executes a program including the step of stopping power supply to an electric motor if a phase of an intake valve is in a first region between the most retarded angle and CA. In the case where the phase of the intake valve is in the first region, the rotational speed of relative rotation between the output shaft of the electric motor and a sprocket is reduced at reduction gear ratio R thereby to vary the phase of the intake valve. In the case where the phase of the intake valve is in a second region between CA and the most advanced angle, the rotational speed of the relative rotation is reduced at reduction gear ratio R thereby to vary the phase of the intake valve.

Abstract: When a variable valve timing device controls an oil pressure control valve in a manner that a VCT phase is locked at a middle lock phase, an advance chamber and a retard chamber are made to communicate with each other, so that oil is filled into both of the advance chamber and the retard chamber when the oil pressure control valve supplies oil to one of the advance chamber and the retard chamber in an oil filling mode. An oil pump supplies oil to the oil pressure control valve, and is controlled to have an oil flow rate that is equal to or larger than a predetermined value in the oil filling mode.

Abstract: A variable valve timing control apparatus includes an abnormality determining portion and a valve controller. The abnormality determining portion determines whether there is an abnormality in a system of a VCT phase control in which an oil pressure control valve is controlled in a manner that an actual VCT phase coincides with a target phase. The valve controller controls the oil pressure control valve to drive a lock pin in a locking direction so as to lock the VCT phase when the abnormality determining portion determines that there is an abnormality in the system of the VCT phase control.

Abstract: A control device for a variable valve timing apparatus that changes valve timing of at least one of an intake valve and an exhaust valve of an internal combustion engine includes an actual valve timing computing unit and a valve timing controlling unit. The actual valve timing computing unit computes actual valve timing. The valve timing controlling unit controls the variable valve timing apparatus to maintain present valve timing during starting of the internal combustion engine before the actual valve timing computing unit becomes capable of computing the actual valve timing. The valve timing controlling unit controls the variable valve timing apparatus such that the actual valve timing becomes target valve timing during the starting of the internal combustion engine after the actual valve timing computing unit becomes capable of computing the actual valve timing.

Abstract: An ECU executes a program including the steps of: controlling, when the phase of an intake valve is a phase advanced relative to a threshold value CA (FF) (NO in S106), an electric motor operating an intake VVT mechanism by feedback control (S202); and controlling, when the phase of the intake valve is a phase retarded relative to the threshold value CA (FF) (YES in S106), the electric motor by feed-forward control (S200). Under the feed-forward control, a duty command value is output that is smaller than an upper limit of a duty command value under the feedback control.

Abstract: In a variable valve timing apparatus having a VVT mechanism in each of a plurality of banks, start of a valve timing control is not permitted until reference position learning of valve timing is completed in the corresponding bank and in other banks. Accordingly, the plurality of banks come to have matching valve timing setting at the time of valve timing control, whereby variation in the amount of air introduced to cylinders can be suppressed, and satisfactory combustion characteristics can be maintained.

Abstract: A valve timing control is executed by an ECU that controls an engine and an electric-motor ECU that controls an electric motor. The ECU and the electric-motor EDU serve different functions. The ECU sets the target phase of an intake valve based on the engine operating state, and prepares a rotational speed command value for the electric motor that serves as an actuator such that a phase feedback control loop, in which the intake valve phase is caused to match the target phase, is formed. The electric-motor EDU forms a feedback control loop for the motor speed, in which the electric power supplied to the electric motor is controlled such that the electric motor rotates in accordance with the rotational speed command value.

Abstract: An ECU transmits a pulsed operation command signal, indicating operation commands for an electric motor used as a VVT actuator, to an electric-motor EDU. The electric-motor EDU recognizes the combination of the direction in which the actuator should be operated (actuator operation direction) and the control mode based on the duty ratio of the operation command signal, and the rotational speed command value based on the frequency of the operation command signal. The electric-motor EDU controls the electric motor according to the control commands. The duty ratio indicating the combination is set such that even if the duty ratio is falsely recognized, a false recognition concerning the actuator operation direction is prevented, such false recognition causing the valve phase to change in an undesirable direction, and even if the actuator operation direction is falsely recognized, the rate of change in the phase is restricted.

Abstract: A variable valve timing controller for an internal combustion engine includes a hydraulic variable valve timing unit, a lock pin, and a hydraulic control valve. The lock pin is configured to lock the VCT phase at an intermediate lock position. The variable valve timing controller controls a valve drive electric current that is used for actuating the hydraulic control valve. The controller controls the valve drive electric current based on a first control characteristic in the operation of the hydraulic control valve under a first control range. The controller controls the valve drive electric current based on a second control characteristic in the operation of the hydraulic control valve under a second control range. The first control characteristic is different from the second control characteristic.