| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent the degradation of the durability and the damage of a motor due to overheating and detect abnormality earlier in an internal combustion engine in which a valve timing is varied by using the motor as the drive source. <P>SOLUTION: An ECU 30 estimates a motor current (drive current for a motor 26) according to a target motor rotational speed, an actual motor rotational speed, and an engine rotational speed. When the estimated motor current exceeds a set value corresponding to a heating limit current value, the varied amount of the target motor rotational speed (corrected amount of rotational speed F/B) output from the ECU 30 to an EDU 31 is limited to limit the motor current controlled for duty by the EDU 31 for suppressing the heating of the motor 26. The variable valve timing device 18 is determined for presence or absence of abnormality according to the deviation between a target cam stem phase and an actual cam stem phase considering that the response of a variable valve timing control is delayed by limiting a motor current when the variable valve timing device 18 is diagnosed for abnormality while a motor current limiting treatment is performed. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
