Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7045496 | Applied Thermal Engineering | 2018 | 11 Pages |
Abstract
VVL and VVT are two common approaches to reduce engine pumping loss at part loads, however, the comparative study on their potentials and influence factors of pumping loss reduction is scarce. In this paper, the gas exchange processes of CVVL and VVT engines were investigated by bench testing. The mechanism and influence factors of pumping loss in the two types of engines were comparatively analyzed, the theoretic limitations of pumping loss in intake process were deduced and the suggestions to approach the theoretic minimum were proposed. The results show that the gross indicated mean effective pressure (IMEP) of engine is approximately proportional to cylinder pressure at bottom dead center (BDC) for both traditional throttle control strategy and early intake valve closing (EIVC) strategy. The difference of pumping losses between CVVL and VVT engines results from intake process. Due to the differences of intake modes, the CVVL engine has lower intake loss than VVT engine by nature. The pumping loss in intake process of CVVL engine is much closer to the theoretical minimum, and the BSFC of CVVL engine can be reduced by more than 20% at 2000â¯r/min and 2.3â¯bar IMEP by increasing the maximum lift of intake valve. All these have provided guidance for pumping loss reduction of gasoline engine.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Qingyu Li, Jingping Liu, Jianqin Fu, Xianjie Zhou, Cheng Liao,