The Correlation between In-Cylinder Air Motion and Engine Performance in Two Intake Valve Engine

Abstract

Recently, two intake valve engines have come into wide use because of their high output performance. However, there exists some difficulties in strengthening the air motion in combustion chamber in order to achieve stable combustion on partial load in a lean mixture operation. In this study improvements in engine performance that result in a stable combustion of lean mixture are examined. These improvments are brought about by the installation of a swirl control valve in the siamesed-type intake port of a two intake valve engine. Characteristics of air motion inside a combustion chamber are also examined using a laser doppler velocimeter. As a result of this study it is clarified that lean stable limit was not always extended in proportion to the strength of tangential swirl and combustion velocity. It is also found that an enlargement of lean stable limit was related to a decrease of cycle by cycle variation.