To effectively achieve substitution of an emulsion fuel to a main fuel in a fuel injection route including a fuel injection valve and a fuel pump, while an internal combustion engine is stopped.
An engine 100 switches between the emulsion fuel and the main fuel by a switching valve 8. The engine 100 includes a fuel pump 9 arranged on the downstream side of the switching valve 8, inlet volume adjusting valves 9a, 9b which adjust the inlet volume of the fuel into the fuel pump 9, the fuel injection valve 11 arranged on the downstream side of the fuel pump 9, a fuel substitution pump 4 which pneumatically transports the main fuel to the fuel injection valve 11 side through a return route 13 where the return fuel of the fuel injection valve 11 circulates, an actuator 22 which drives the fuel pump 9 while the engine 100 is stopped, an emulsion fuel accumulating section 17 which retrieves and accumulates fuel flown out of the fuel pump 9 and the fuel injection valve 11 through a fuel retrieving route 20, and a three-way valve 21 which blocks the circulation of the fuel inside the fuel retrieving route 20.
Toshiyuki Hatta
High Yoshitaka Hayashi