Abstract: A control duty is obtained, which asymptotically makes the output of a control subject consistent with an output of a reference model. The output of the control subject simulates a dynamic characteristic of a variable valve timing controller, and the output of the reference model simulates an ideal input-output characteristic of the variable valve timing. The control duty makes a difference between the output of the reference model and an actual valve timing small enough. A parameter of a controller is consecutively corrected to make the difference small by means of a parameter correcting mechanism when the dynamic characteristic of the variable valve timing controller is varied due to a variation of an operating environment thereof so that the difference becomes large.

Abstract: An ECU calculates an engine speed for calculating a camshaft phase based on a time period T? in which a crankshaft rotates a sampling angle ?. The camshaft phase is derived from a time difference between output timing of a cam angle signal and output timing of a crank angle signal based on the engine speed. According as the engine speed is lower, the sampling angle ? becomes small, so that the engine speed and the camshaft phase are precisely calculated.

Abstract: The valve timing controller is driven by a motor. The valve controller has a control circuit and a driving circuit. The driving circuit receives a control signal generated by the control circuit and an engine rotation speed signal. The driving circuit supply a current to the motor to drive it based on the engine rotation speed represented by engine rotation speed signal and a target variation of the motor rotation speed represented by the control signal.

Abstract: A required valve timing change rate Vreq is calculated so as to make a deviation D between a target valve timing VTtg and an actual valve timing VT small and then a required speed difference DMCRreq between a motor 26 and a camshaft 16 is calculated on a basis of the required valve timing change rate Vreq. When the deviation D is larger than a predetermined value, a required motor speed Rmreq is calculated by adding the required speed difference DMCRreq to a camshaft speed RC and a motor control value is calculated so as to control the motor speed RM to the required motor speed Rmreq. When the deviation D is not larger than the predetermined value, the camshaft speed RC is set as the required motor speed Rmreq and the motor control value is calculated so as to control the motor speed RM to the camshaft speed RC.

Abstract: An electric variable valve timing mechanism and a starter are actuated by electricity supplied from a common battery. During an engine starting process, the starter is actuated, and an electronic control unit controls the electric variable valve timing mechanism. The electronic control unit limits the actuation of the electric variable valve timing mechanism on the condition that, during the engine starting process, the voltage value of the battery falls below a predetermined threshold value that degrades the operation of the starter. As a result, the engine is started in a stable manner.

Abstract: A required valve timing change rate Vreq is calculated so as to make a deviation D between a target valve timing VTtg and an actual valve timing VT small and then a required speed difference DMCRreq between a motor 26 and a camshaft 16 is calculated on a basis of the required valve timing change rate Vreq. When the deviation D is larger than a predetermined value, a required motor speed Rmreq is calculated by adding the required speed difference DMCRreq to a camshaft speed RC and a motor control value is calculated so as to control the motor speed RM to the required motor speed Rmreq. When the deviation D is not larger than the predetermined value, the camshaft speed RC is set as the required motor speed Rmreq and the motor control value is calculated so as to control the motor speed RM to the camshaft speed RC.

Abstract: At an intake timing of an initial combustion cylinder, an actual intake valve timing is adjusted to a target intake valve timing corresponding to a target intake air flow rate of the initial combustion cylinder. At intake timing of the other cylinders which contributes to increment of the engine speed after the initial combustion, the actual intake valve timing is adjusted to a target valve timing corresponding to a target intake air flow rate of the other cylinders. Thereby, the intake air flow rate of each cylinder is accurately controlled, so that the increment of the engine speed is restricted within a range in which a startability is not deteriorated and a vehicle vibration and an over shoot of the engine speed is appropriately restricted.

Abstract: An ECU calculates an engine speed for calculating a camshaft phase based on a time period T? in which a crankshaft rotates a sampling angle ?. The camshaft phase is derived from a time difference between output timing of a cam angle signal and output timing of a crank angle signal based on the engine speed. According as the engine speed is lower, the sampling angle ? becomes small, so that the engine speed and the camshaft phase are precisely calculated.

Abstract: A control duty is obtained, which asymptotically makes the output of a control subject consistent with an output of a reference model. The output of the control subject simulates a dynamic characteristic of a variable valve timing controller, and the output of the reference model simulates an ideal input-output characteristic of the variable valve timing. The control duty makes a difference between the output of the reference model and an actual valve timing small enough. A parameter of a controller is consecutively corrected to make the difference small by means of a parameter correcting mechanism when the dynamic characteristic of the variable valve timing controller is varied due to a variation of an operating environment thereof so that the difference becomes large.

Abstract: An internal combustion engine has a variable valve timing apparatus including a driving motor between a crankshaft and a camshaft. The driving motor rotates synchronously with the camshaft when the valve timing apparatus is not in operation. A motor rotation sensor produces a motor rotation signal. When the engine rotation speed is below a reference speed, the driving motor is not energized. Under this condition, the rotation speed and the rotation direction of the engine are calculated based on the motor rotation signal in place of a crank rotation signal produced by a crank angle sensor. Further, the rotation stop position of the engine is calculated based on the motor rotation signal when the engine is stopped.

Abstract: A variable valve timing controller adjusts valve timing of an intake valve and/or an exhaust valve by varying a motor speed relative to a camshaft. When an engine is running under a predetermined condition, an actual valve timing is calculated based on a cam angle signal and crank angle signal every when the cam angle signal is inputted. A final valve timing is calculated by adding a valve timing variation amount to the actual valve timing at the time the cam angle signal is outputted. The valve timing amount is periodically calculated based on a difference between a motor speed and a rotational speed of the intake camshaft. When the engine is running under another condition, only actual valve timing at the time the cam angle signal is outputted is calculated.

Abstract: A control unit employed in a variable valve timing apparatus vibrates a control signal for controlling an oil-pressure control valve. If the vibration center of the duty value of the control signal for driving the oil-pressure control valve lies in a dead band, the vibration takes the duty value to the outside of the dead center temporarily. Thus, even if the center value of the control signal lies in the dead band, the valve timing of the oil-pressure control valve changes with variations in control signal. As a result, the width of the dead band appears small or to have a value of zero. Accordingly, the response characteristic of variations in valve timing to the variations in control signal is improved. The vibration of the control signal is also effective for detection of a width of the dead band.

Abstract: A required valve timing change rate Vreq is calculated so as to make a deviation D between a target valve timing VTtg and an actual valve timing VT small and then a required speed difference DMCRreq between a motor 26 and a camshaft 16 is calculated on a basis of the required valve timing change rate Vreq. When the deviation D is larger than a predetermined value, a required motor speed Rmreq is calculated by adding the required speed difference DMCRreq to a camshaft speed RC and a motor control value is calculated so as to control the motor speed RM to the required motor speed Rmreq. When the deviation D is not larger than the predetermined value, the camshaft speed RC is set as the required motor speed Rmreq and the motor control value is calculated so as to control the motor speed RM to the camshaft speed RC.

Abstract: The valve timing controller is driven by a motor. The valve controller has a control circuit and a driving circuit. The driving circuit receives a control signal generated by the control circuit and an engine rotation speed signal. The driving circuit supply a current to the motor to drive it based on the engine rotation speed represented by engine rotation speed signal and a target variation of the motor rotation speed represented by the control signal.

Abstract: The variable valve timing controller controls the valve timing of the intake valve. The variable valve timing controller has a shaft, the stator fixed on the engine and generating the magnetic field around the shaft and rotational phase converter converting the torque applied to the shaft. When the valve timing is in the most delayed timing, the engine can be started. The rotational phase of this timing is called the feasible phase. When the stator stops generating the magnetic field, the load torque arise on the shaft. The rotational phase converter varies the rotational phase into the feasible phase with receiving the load torque from the shaft.

Abstract: The variable valve timing controller controls the valve timing of the intake valve. The variable valve timing controller has a shaft, the stator fixed on the engine and generating the magnetic field around the shaft and rotational phase converter converting the torque applied to the shaft. When the valve timing is in the most delayed timing, the engine can be started. The rotational phase of this timing is called the feasible phase. When the stator stops generating the magnetic field, the load torque arise on the shaft. The rotational phase converter varies the rotational phase into the feasible phase with receiving the load torque from the shaft.

Abstract: A control unit employed in a variable valve timing apparatus vibrates a control signal for controlling an oil-pressure control valve. If the vibration center of the duty value of the control signal for driving the oil-pressure control valve lies in a dead band, the vibration takes the duty value to the outside of the dead center temporarily. Thus, even if the center value of the control signal lies in the dead band, the valve timing of the oil-pressure control valve changes with variations in control signal. As a result, the width of the dead band appears small or to have a value of zero. Accordingly, the response characteristic of variations in valve timing to the variations in control signal is improved. The vibration of the control signal is also effective for detection of a width of the dead band.

Abstract: An engine valve operation timing control apparatus having a learning control function determines whether both of an actual phase difference angle and a target value between a crankshaft and a camshaft are almost constant for a predetermined time. When both of the actual phase difference angle and the target value become almost constant for the predetermined time, a control value is learned. A controller outputs the learned value to driving means to find a control value thereafter based on the learned value. As a result, the learning means learns the control value in correspondence with a rate of change of the actual phase difference angle and the control value found by the controller compensates for a disturbance factor. The learning operation is updated every time the actual phase difference angle and the target value converge to a constant value and is repeated when the convergence state continues.