Kinematic structure analysis of variable compression ratio engine mechanisms

Abstract

Due to environmental issues and regulations, there have been numerous efforts to develop high efficient environmentally friendly vehicle engines among the automotive industry and academia. One of such developments is variable compression ratio(VCR) engine technology that improves fuel efficiency by varying the compression ratio of an internal combustion engine according to the vehicle performance needs. There are many patents and research papers related to variable compression ratio engines, however, no VCR engine has succeeded in being put to commercial use yet. In this paper, VCR engines are analyzed from the viewpoint of kinematic structure. For this, various VCR engine mechanisms appeared in patents and research literature are represented in conventional and contracted graphs which enable easy comparisons of VCR engine mechanism structures by expressing the connectivity of links of the mechanisms. It is found that some VCR engine mechanisms share the same kinematic structure. © Copyright 2018 KSAE / 153-02.