| abstract |
The purpose of the present invention is to inhibit any excessive increase in the amount of HC emission in a compression-ignition multifuel internal combustion engine capable of mixed combustion of a liquid fuel that can be subjected to compression ignition and a gas fuel having methane as the principal component. In the present invention, the required mixing ratio between the liquid fuel and the gas fuel, and the required HC emission, are calculated on the basis of the operation state of the multifuel internal combustion engine (S103, S104). Then, the required compression ratio, at which the HC emission from the multifuel internal combustion engine is equal to the required HC emission, is calculated on the basis of the required mixing ratio and the required HC emission (S105), and the compression ratio of the multifuel internal combustion engine is controlled so as to match the required compression ratio (S107). |