Variable valve timing apparatus with reduced power consumption and control method thereof

A variable valve timing apparatus changing an opening/closing timing of at least any one of an intake valve and an exhaust valve provided to an engine, comprising:

• an actuator;
• a change mechanism changing said opening/closing timing by changing difference in rotational phase of a camshaft driving the valve having said opening/closing timing changed, from a rotational phase of a crankshaft, at an amount of change according to an operation amount of said actuator;
• and
• a control unit setting the operation amount of said actuator, based on a deviation between said opening/closing timing at present of the valve having said opening/closing timing changed and a target value thereof, wherein
• said control unit sets the operation amount of said actuator to approximately zero, when an absolute value of said deviation is equal to or smaller than a determination value, and in addition, in changing said opening/closing timing during a course of engine stop, sets said determination value at a value larger than said determination value in changing said opening/closing timing at a time of engine operation.

A control method of a variable valve timing apparatus changing an opening/closing timing of at least any one of an intake valve and an exhaust valve provided to an engine,

• said variable valve timing apparatus including
• an actuator,
• a change mechanism changing said opening/closing timing by changing difference in rotational phase of a camshaft driving the valve having said opening/closing timing changed, from a rotational phase of a crankshaft, at an amount of change according to an operation amount of said actuator, and
• an actuator operation amount setting portion setting the operation amount of said actuator, based on a deviation between said opening/closing timing at present of the valve having said opening/closing timing changed and a target value thereof, said control method comprising:
• a convergence determination step of setting the operation amount of said actuator to approximately zero, when an absolute value of said deviation is equal to or smaller than a determination value;
• and
• a determination value switching step of setting, in changing said opening/closing timing during a course of engine stop, said determination value at said convergence determination step at a value larger than said determination value in changing said opening/closing timing at a time of engine operation.