Control device for direct fuel injection engine and control method thereof

A control device for a direct fuel injection engine comprising:

• an ignition plug;
• a fuel injection valve arranged to be capable of injecting a fuel directly in a cylinder;
• and
• a controller configured to control operation of the ignition plug and the fuel injection valve,
• the engine having an operation region in which an excess air ratio of an air-fuel mixture is set in a vicinity of 2 and being configured to perform, in the operation region, spark ignition combustion with the ignition plug, wherein
• the controller is configured to:
• detect an operation state of the engine;
• set an injection amount and an injection timing of the fuel injection valve on the basis of the operation state of the engine;
• and
• set an ignition timing of the ignition plug;
• and
• the controller sets:
• when the engine operation state is in a first region of the operation region, the injection amount and the injection timing to form a homogenous air-fuel mixture having the excess air ratio of the air-fuel mixture at a first predetermined value in the vicinity of 2;
• and
• when the engine operation state is in a second region of the operation region on a load side higher than the first region, the injection amount and the injection timing to form a stratified air-fuel mixture having the excess air ratio of the air-fuel mixture at a second predetermined value in the vicinity of 2.