Patent ID: 7690369

Claim:
A fuel pressure controlling device for a four stroke engine having a cylinder, the device comprising: a fuel injection device for injecting fuel into the cylinder; an ignition device for igniting a mixture of the injected fuel and air; a catalyst for removing pollutants from exhaust emitted by the engine; and a controller for controlling the fuel injection device and the ignition device, the controller being configured to select a combustion mode of the engine from at least a homogeneous combustion mode in which the fuel injection device injects the fuel during the intake stroke of the cylinder and the ignition device ignites the fuel before compression top dead center; wherein the controller is configured to control the fuel injection device to inject the fuel based on a target fuel pressure according to the selected combustion mode, and to detect whether or not a request is present for raising the temperature of the catalyst; and wherein in the homogenous combustion mode, when the controller detects that a request is present for raising the temperature of the catalyst, the controller sets the target fuel pressure to be a first target fuel pressure, and when the controller detects that a request is not present for raising the temperature of the catalyst, the controller sets the target fuel pressure to be a second target fuel pressure, the second target fuel pressure being lower than the first target fuel pressure.