Control device and control method for variable valve timing mechanism
A control device and a control method for variable valve timing mechanism according to the present invention obtains a first measurement of a rotational phase based on a rotational angle of the motor, obtains a second measurement of the rotational phase based on a relative relationship between a rotational angle of the crankshaft and a rotational angle of the camshaft, calibrates the first measurement based on the second measurement, obtains a derivative term proportional to a rate of change in a deviation between the first measurement and a target value, reduces change in derivative term when calibrating the first measurement based on the second measurement, and controls the motor based on a manipulated variable including the derivative term.
1. A control device of a variable valve timing mechanism that makes a rotational phase of a camshaft variable relative to a crankshaft of an internal combustion engine by adjusting rotation of a motor, the control device being configured to:
obtain information on a rotational angle of the motor, information on a rotational angle of the crankshaft, and information on a rotational angle of the camshaft;
obtain a first measurement of the rotational phase based on the rotational angle of the motor;
obtain a second measurement of the rotational phase based on a relative relationship between the rotational angle of the crankshaft and the rotational angle of the camshaft;
calibrate the first measurement based on the second measurement;
obtain a derivative term proportional to a rate of change in a deviation between the first measurement and a target value of the rotational phase;
reduce change in derivative term when calibrating the first measurement based on the second measurement;
obtain a manipulated variable of the motor based on the derivative term; and
control the motor based on the manipulated variable.
2. The control device of the variable valve timing mechanism according to claim 1 , wherein the control device is configured to reduce change in the derivative term so that an amount of change between a derivative term obtained from the first measurement and a derivative value obtained from the calibrated first measurement becomes less than a predetermined value.
3. The control device of the variable valve timing mechanism according to claim 1 , wherein the control device is configured to reduce change in the derivative term by obtaining the manipulated variable, using a derivative term obtained from the first measurement.
4. The control device of the variable valve timing mechanism according to claim 1 , wherein the control device is configured to reduce a calibration frequency of the first measurement as a rotational speed of the internal combustion engine increases.
5. A control method for a variable valve timing mechanism that makes a rotational phase of a camshaft variable relative to a crankshaft of an internal combustion engine by adjusting rotation of a motor, the control method comprising the steps of:
obtaining a first measurement of the rotational phase based on a rotational angle of the motor;
obtaining a second measurement of the rotational phase based on a relative relationship between a rotational angle of the crankshaft and a rotational angle of the camshaft;
calibrating the first measurement based on the second measurement;
obtaining a derivative term proportional to a rate of change in a deviation between the first measurement and a target value of the rotational phase;
reducing change in the derivative term when calibrating the first measurement based on the second measurement; and
controlling the motor based on a manipulated variable including the derivative term.