A Fully Hydraulic Variable Valve System is described in this article which can achieve continuous variation in valve lift, duration, and timing. The system was installed in a four-cylinder port fuel injection spark ignition engine and achieved unthrottled load control through early intake valve closing. The in-cylinder pressure measured experimentally showed that pumping losses of the unthrottled spark ignition engine at 2000 r/min and 0.189 MPa brake mean effective pressure was reduced by 85.4% compared with the throttled spark ignition engine. However, its slow and unstable combustion reduced the indicated thermal efficiency. Compared with the throttled spark ignition engine, the amount of residual exhaust flowing back into the intake port was greatly reduced at the early stage of the intake process. Consequently, it negatively influenced fuel evaporation and fuel–air mixing processes in the intake port of the port fuel injection spark ignition engine and decreased the flow of in-cylinder gases, which resulted in a low combustion rate. A new centrosymmetric helical valve is proposed in this article to improve the fuel–air mixing and combustion rate of the unthrottled spark ignition engine. The experiments demonstrate that the helical valve can generate a strong intake swirl at small intake valve lift. It helps to increase combustion rate and lower cycle-to-cycle variation, which improves indicated thermal efficiency and fuel economy of the unthrottled spark ignition engine at low load.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Effect of intake swirl on combustion performance in an unthrottled spark ignition engine


    Contributors:
    Zhang, Kaiyu (author) / Chang, Yingjie (author) / Xie, Zongfa (author) / Sun, Tingting (author) / Chen, Fei (author)


    Publication date :

    2019-04-01


    Size :

    11 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




    Characteristics of an Unthrottled, Auxiliary Chamber, Spark Ignition Engine

    Freeman, J. H. / Dysart, W. D. | SAE Technical Papers | 1963


    The effect of swirl on spark-ignition engine combustion

    Hamamoto,Y. / Tomita,E. / Tanaka,Y. et al. | Automotive engineering | 1985



    A study of alcohol blended fuels in an unthrottled single cylinder spark ignition engine

    Cairns,A. / Todd,A. / Aleiferis,P. et al. | Automotive engineering | 2010


    A Study of Alcohol Blended Fuels in an Unthrottled Single Cylinder Spark Ignition Engine

    Todd, Alan / Cairns, Alasdair / Malcolm, John et al. | SAE Technical Papers | 2010