Direct fuel injection type internal combustion engine

In a direct fuel injection type internal combustion engine comprising a combustion chamber having a piston movably received therein, the piston having a cavity;

• a fuel injection valve arranged to inject fuel against a wall of the cavity of the piston thereby to produce an air-fuel mixture;
• and an ignition plug arranged to ignite the air-fuel mixture,
• a method of controlling the engine, comprising:
• controlling the fuel injection valve to have a first fuel injection mode wherein a penetration force of the injected fuel sharply increases at an initial stage of the fuel injection and thereafter an increasing rate of the penetration force gradually lowers with passage of time and a second fuel injection mode wherein the penetration force of the injected fuel sharply increases at a middle stage of the fuel injection;
• and
• switching the first and second fuel injection modes in accordance with an operation condition of the engine.