Investigation On Dynamics Simulation Of A Gasoline Engine With Variable Mechanical System

With the growth in living standards, automobiles have been increasingly popular.Presently, China has become the world’s largest automobile market and the carownership reaches120million, which poses a great burden to the energy and theenvironment and pressuring the government to announce more restrictive emissionregulations. In response to energy saving and emission reduction of engines, variablecompression ratio (VCR) and variable valve timing (VVT) technology can improvethe engine power, fuel economy and reduce emissions significantly.In this paper, a new kind of VCR and VVT mechanism has been applied on asingle-cylinder gasoline engine. Based on the three-dimensional model of the originalengine, parts of the mechanism was designed by PROE and finally assembled into it.In order to reduce the vibration, the way of balancing the first order componentsof the inertia force was changed from excessive balance to single shaft balance, andbetter effect was achieved. With the check of gears of VCR mechanism in classicalmethod and finite element method, it is found that the results achieved by using finiteelement method is lower than the one of classical method, which indicated that theformer was more conservative, and gears’ strength could meet requirements. Then thecam profile of the original engine was optimized by using AVL-TYCON to reducethe maximum cam contact stress. Finally, considering that the deformation of therocker arm and valve in valve train mechanism is relatively high, the way of flexiblemulti-body analysis had been used by using flexible valve and rocker arm. The resultsshowed that flexible multi-body simulation was more accurate, which could meet theaccuracy requirement.