| 摘要 |
PROBLEM TO BE SOLVED: To accurately calculate estimated oil temperature of working fluid of a variable valve timing device.SOLUTION: An average value of start cooling water temperature THWst detected by a cooling water temperature sensor 26 and start intake air temperature THAst detected by an intake air temperature sensor 27 is corrected according to difference between the start cooling water temperature THWst and the start intake air temperature THAst at engine start, and start estimated oil temperature THOst (initial value of estimated oil temperature THO) is accurately calculated. Engine rotation speed is integrated after engine start (during engine operation), estimated oil temperature rise quantity ΔTHO is accurately calculated according to the integrated value of engine rotation speed, and estimated oil temperature THO is accurately determined by adding the estimated oil temperature rise quantity ΔTHO to the start estimated oil temperature THOst. If the estimated oil temperature THO gets higher than cooling water temperature THW (cooling water temperature detected by the cooling water temperature sensor 26), it is determined that actual oil temperature rises to temperature roughly same as cooling water temperature and the cooling water temperature THW is defined as the estimated oil temperature THO. |
