火花点火機関におけるノッキング及びプレイグニッション克服への課題

抄録

Spark ignition engines are widely used for a small generator as well as a passenger vehicle. The exhaust gas emissions no longer have pollution problem by adopting a combination of three-way catalyst and stoichiometric mixture control, but an improvement of thermal efficiency is an urgent task. To achieve this, an increase of compression ratio and down-sizing with a turbo-charger are solutions. However, employing these methods causes abnormal combustion of such as knocking and pre-ignition that will bring about damages to engine components. In this article, why these phenomena occur and how to solve the issues are briefly mentioned with some author's ideas: since autoignition itself does not lead to a heavy knocking, a quick expansion at early expansion stroke and a spatial temperature distribution of mixture inside the cylinder can control the knocking intensity. As pre-ignition at low engine speed is not well analyzed, this phenomenon must be quantitatively examined.