In the conventional homogeneous-charge spark-ignition engine, fixed lift characteristics and timings for opening and closing of the intake and exhaust valves compromise efficiency and maximum power. In order to minimize the compromise, numerous variable-valve-actuation (VVA) systems have been proposed in the past that give adjustable valve operation depending on the engine-operating condition. A literature survey was conducted of the vast array of VVA devices that have been tested and/or analyzed in order to compare attributes of different systems.The review indicates that the chief benefit of phase-shift systems, the ability to extract more power from a given-displacement engine without compromising idle stability, has been demonstrated conclusively. However, assessments of the potential benefits of the devices with variable-lift capability are less reliable because of the limited scope of past studies, lack of effort to separate the effects of different variables, and unreliability of data.


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    Title :

    A Survey of Variable-Valve-Actuation Technology


    Additional title:

    Sae Technical Papers


    Contributors:
    Theobald, M. A. (author) / Ahmad, T. (author)

    Conference:

    1989 Conference and Exposition on Future Transportation Technology ; 1989



    Publication date :

    1989-08-01




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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