| 摘要 |
PROBLEM TO BE SOLVED: To prevent a MOSFET (switching element) provided for energization control of a motor of an electric type variable valve timing apparatus from being overheated.SOLUTION: An oil temperature rise portion with respect to a cooling water temperature is calculated based on an engine operating state (for example, an engine speed and a load), a base oil temperature is obtained by adding the oil temperature rise portion to the cooling water temperature, the oil temperature is obtained by weightedly averaging the base oil temperature, and the oil temperature is estimated thereby. A base substrate temperature is calculated based on the estimated oil temperature and the cooling water temperature, the base substrate temperature is weightedly averaged to obtain a substrate temperature (the temperature of a substrate 33), and the substrate temperature is estimated thereby. Current limit control for limiting a MOS current is performed so that a MOS temperature (the temperature of the MOSFET 32) does not exceed a permissible upper limit temperature by limiting the MOS current (the current running in the MOSFET 32) by a predetermined upper limit guard value when the estimated substrate temperature is higher than the predetermined upper determination value. |
