DIESEL ENGINE SYSTEM, METHOD OF CONTROLLING DIESEL ENGINE SYSTEM, AND COMPUTER PROGRAM PRODUCT

A diesel engine system has a piston in which a cavity is formed in a crown surface. The cavity has a bottom part, a peripheral part dented so as to be convex radially outward in a cross-sectional view, and a lip part formed above the peripheral part and protruding so as to be convex radially inward in the cross-sectional view. An injection controller causes an injector to perform, during operation in a given operating range, a main injection in which injected fuel is directed to the lip part, and an after-injection in which a smaller amount of fuel than the main injection is injected at a given period later than the main injection in an expansion stroke. An injection interval period that is a period of time from an end of the main injection to a start of the after-injection is shorter as an injection pressure of fuel increases.