To securely prevent fuel leakage from a fuel injection valve at the time of stop, without deteriorating startability at the time of restart, in regard to a fuel supply system for an internal combustion engine.
Necessary bubble amount inside a fuel supply passage so as not to increase fuel pressure again after closing of a solenoid valve is estimated. As an estimate method of the necessary bubble amount, for example, an increase degree of fuel temperature inside the fuel supply passage increasing accompanied by the stop of the internal combustion engine is predicted, and based on the predicted increase degree of the fuel temperature, the necessary bubble amount can be estimated. Since bubble amount depends on valve opening time of the solenoid valve, necessary valve opening time of the solenoid valve can be determined based on the estimated necessary bubble amount, and the solenoid valve is operated on the basis of the necessary valve opening time at the time of stop of the internal combustion engine.
Mamoru Takada
Atsushi Hirayama