Fuel injection control device for direct-injection engine

A fuel injection control device for a direct-injection engine, the control device comprising:

• an engine body including a combustion chamber defined by a cylinder head ceiling portion, a cylinder provided for a cylinder block, and a piston reciprocating inside the cylinder;
• and
• a fuel injection control unit which includes a fuel injection valve, provided inside the combustion chamber to inject a liquid fuel, and which is configured to inject the fuel into the combustion chamber at a predetermined timing, wherein
• the fuel injection control unit performs a main injection over a period ranging from a last stage of a compression stroke to an initial stage of an expansion stroke, and also performs a preceding injection, injecting a smaller amount of the fuel than the main injection, over a period ranging from an intake stroke to a first half of the compression stroke, and
• the fuel injection control unit also determines whether or not the fuel injected by the preceding injection causes a partial oxidation reaction during a second half of the compression stroke, and on determining that the fuel causes the partial oxidation reaction, performs a middle-stage injection between the preceding injection and the main injection, and
• the fuel injection control unit performs the middle-stage injection at such a timing that allows the fuel injected by the middle-stage injection to ignite spontaneously on or after the fuel injected by the main injection has spontaneously ignited and before the partial oxidation reaction occurs during the second half of the compression stroke.