Scavenging Characteristics and Valve Timing Strategy Optimization in Full Load of Turbocharged GDI Engine
Author(s): SONG Yi-zhong, HU Wei, SHI Lei, DENG Kang-yao, SUN Wei-qing, JIN Rong
Pages: 49-54
Year: 2014 Issue: 4
Journal: Vehicle Engine
Keyword: gasoline engine; valve timing; scavenging; residual gas;
Abstract: Based on the calculated model established by GT-Power software ,the intake and exhaust pressure fluctuation was analyzed .The speed range of available scavenging was determined by analyzing the relation of scavenging mass with intake and exhaust pressure difference in seven operating conditions .The effect of valve timing on engine performance was discussed in conditions of maximum torque and rated power and the optimization strategy of valve timing in full load was put forward .The results show that the positive pressure difference exists and the scavenging coefficient is 1 .03 near exhaust TDC in 1 000~2 700 r/min .In the maximum torque condition ,increasing valve overlap angle can increase the scavenging coefficient and the temperature before the turbine will decrease .In the rated power condition ,the coefficient of residual gas reaches the minimum when EVC is around 353°ATDC .After optimizing the valve timing ,the intake air mass increases by 19% ,the coefficient of re-sidual gas decreases by 0 .018 and the power increases by 21% in full load condition of 6 000 r/min .In the maximum torque condition ,the pressure after compressor improves by 11 .7% and the pressure before turbine increases by 19 .4% .
Pages: 49-54
Year: 2014 Issue: 4
Journal: Vehicle Engine
Keyword: gasoline engine; valve timing; scavenging; residual gas;
Abstract: Based on the calculated model established by GT-Power software ,the intake and exhaust pressure fluctuation was analyzed .The speed range of available scavenging was determined by analyzing the relation of scavenging mass with intake and exhaust pressure difference in seven operating conditions .The effect of valve timing on engine performance was discussed in conditions of maximum torque and rated power and the optimization strategy of valve timing in full load was put forward .The results show that the positive pressure difference exists and the scavenging coefficient is 1 .03 near exhaust TDC in 1 000~2 700 r/min .In the maximum torque condition ,increasing valve overlap angle can increase the scavenging coefficient and the temperature before the turbine will decrease .In the rated power condition ,the coefficient of residual gas reaches the minimum when EVC is around 353°ATDC .After optimizing the valve timing ,the intake air mass increases by 19% ,the coefficient of re-sidual gas decreases by 0 .018 and the power increases by 21% in full load condition of 6 000 r/min .In the maximum torque condition ,the pressure after compressor improves by 11 .7% and the pressure before turbine increases by 19 .4% .
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