Investigation on the Effect of Valve Overlap Angle on Atkinson Cycle Engine
Based on the bench test of a 1.5 L naturally aspirated engine with Atkinson cycle,the influ-ence of different valve overlap angles on the engine was studied.The test results show that,with the in-crease of valve overlap angle,the charging efficiency of engines and the torque increased,while the effi-ciency of combustion and ignition angle variation became worse.The fuel consumption decreased slightly in the stable combustion area in the small valve overlap angle area,but increased in the large valve over-lap angle area.The hydrocarbon and nitrogen oxide emissions generally showed a downward trend,but the unstable combustion lead to the increase of hydrocarbon emissions when the overlap angle increased to a certain extent under low load conditions.
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