Analysis Of The Combustion Phenomena Under The Cold Starting Condition And The Improvement Of Cold Startability By A Programmed Control System

Fuel injection timing retardation for reducing exhaust emission of direct injection diesel engines prolongs the period to complete cold starting. Engine speed at this period varies through some accelerating and faltering stages and a longer faltering stage increases the cold starting period.

Engine speed variation during cold starting is determined by the difference between engine friction and the torque generated by combustion. So the frictional losses of piston and crankshaft were studied first and engine overall friction was calculated through combustion torque and instantaneous engine speed. As for the combustion, cylinder pressure was measured for each cylinder and, in relation with the dynamic fuel injection timing and engine speed, the variation of combustion characteristics during cold start was investigated.

An improvement of cold start was shown by application of afterheat of a sheathed type glow plug and an electronic fuel injection timing control device.