Control device for internal combustion engine and control method for internal combustion engine

A control device for an internal combustion engine including a fuel reformation cylinder and an output cylinder to which reformed fuel generated in the fuel reforming cylinder is supplied, the output cylinder being configured to yield an engine power by combusting the reformed fuel, the control device comprising:

• a reforming operation control unit configured not to execute a fuel reforming operation in the fuel reformation cylinder, when a gas temperature in the fuel reformation cylinder at a time point when a periodically changing gas temperature in the fuel reformation cylinder reaches its highest temperature is estimated to fall short of a reforming operation allowable lower limit gas temperature set based on a lower limit value of a reforming reaction enabling temperature;
• and
• wherein:
• the reforming operation allowable lower limit gas temperature is set so as to be higher with an increase in an air fuel mixture equivalence ratio in the fuel reformation cylinder;
• the fuel reformation cylinder is structured as a reciprocation type cylinder;
• and
• the gas temperature reaches its highest temperature when a piston in the fuel reformation cylinder reaches a compression top dead point.