Diesel engine

A diesel engine comprising:

• a fuel injection device;
• and
• a controller for controlling said fuel injection device in accordance with an operating condition of the engine, said controller providing a preliminary injection signal wherein a first predetermined amount of fuel is injected into a cylinder of the engine during a period from the initial part of an intake stroke to the middle part of a compression stroke, said controller further providing a main injection signal wherein a second predetermined amount of fuel is injected into a combustion chamber in the vicinity of top dead center of the compression stroke, whereby a maximum combustion temperature in said combustion chamber is decreased to suppress generation of NOx and to reduce emission of black smoke.