Analysis And Research Of Atkinson Cycle Engine

With the rapid development of global economy,auto industry has become a pillar industry.The traditional internal combustion engine technologies cannot meet the high efficiency target in the future.So more and more enterprises focus on Atkinson Cycle for the higher combustion efficiency.And Atkinson cycle is widely used on production vehicle now.Compared to Otto engine,Atkinson engine can reduce pumping losses,increase expansion ratio,thereby,reducing fuel consumption,and improving efficiency.So it has attracted a wide spread attention.This research focus on the development of GAC 1.5L Atkinson cycle engine which used on GAC hybrid vehicle and using GT-Power to establish the one-dimension model for the selection of optimal cam profile and air intake manifold structure.By comparing the two cam profile selection methods,GT suit—VT design and 7 time polynomial function,we confirmed the cam profile designed by 7 time polynomial function for simulating calibration.In this research,the influence of cam contour,maximum valve lift,valve angle and some other parameters on engine performance was analyzed;furthermore,this research also investigated the influence of plenum volume,intake manifold length and air intake type.According to the research,by comparison of power,fuel combustion and cylinder pressure,the one-dimension simulation calibration results agrees the testing result well;by using 240° cam contour,the fuel combustion would be decreased under 2000r/min and 3000r/min,and the torque would increase under the whole speed range.Decreasing the intake manifold length to 300mm gives the lowest fuel combustion.As to the middle inlet manifold,plan 3(intake manifold length is 100mm,plenum volume is 1L,air intake section keeps unchanged)could modify the performance of intake manifold under low speed and increase the torque under high speed.