Fuel reforming system for vehicle with engine mounted thereon

A fuel reforming system for a vehicle, the fuel reforming system comprising:

• a reciprocating engine mounted on the vehicle and in which a piston in a cylinder reciprocates;
• a decomposer that decomposes a hydrocarbon fuel into carbon and a hydrogen gas;
• and
• a hydrocarbon fuel supply device that supplies the hydrocarbon fuel to the decomposer, wherein
• the reciprocating engine includes an intake port, an exhaust port, and a third port that allows the cylinder and the decomposer to communicate and that is opened and closed by an on-off valve,
• the on-off valve opens in a stroke in which a combustion gas inside the cylinder is supplied to the decomposer with ascending of the piston,
• the on-off valve opens in a stroke in which a combustion gas, in which the carbon and the hydrogen gas has been removed, is introduced from the third port to the cylinder with descending of the piston,
• the decomposer includes a catalyst portion that decomposes the hydrocarbon fuel using a catalyst and a space that is on a side opposite to the third port across the catalyst portion, the space being connected to the catalyst portion, and
• the hydrocarbon fuel supply device injects the hydrocarbon fuel into the space during a stroke in which the on-off valve is opened and the piston is ascending.