Combustion Control of a Swirl-Chamber Type Diesel Engine by Early Ignition of Residual Fuel from the Previous Cycle

During our investigations using an ion-gap, we observed a rise of the ion-current before the injection event.

We then tried to trap some portion of the fuel spray in the swirl-chamber to cause early ignition in the next cycle in order to get the effect of pilot injection.

As a result, a very smooth pressure rise was attained and the objectionable knocking noise at idling was eliminated.

However, we had to make compromises when taking advantage of this combustion mechanism, as there was a trade-off between noise level and HC emission.