A Study on Combustion State and Engine Speed Response under Transitional Operation of Small Spark Ignition Engines

摘要

There are various running modes of an internal combustion engine and a considerable percentage of them is occupied by such transient operation that the engine speed and brake load change. Even in such transient running as these, it is desired to improve the power performance, to reduce the exhaust emission and engine noise, to make the speed responsiveness better etc. In particular, since the characteristics of a spark ignition engine with a carburetor depends remarkably on the air-fuel ratio of mixture in the cylinder, it is necessary to feed always an appropriate mixture to the cylinder also during the transient operation. However, some part of fuel fed from the carburetor is fed into the cylinder together with intake air, whereas the remaining fuel not yet gasified flows into the cylinder along the intake pipe wall. For this reason, the state of mixture formation in the cylinder during transient operation depends on the behavior of the fuel liquid-film formed on the inside wall of