Reducing power loss caused by friction between the parts in a motorcycle engine is an effective way to decrease fuel consumption and increase power. In this study we attempted to reduce friction loss between the tappets and cams by applying a hard thin coating to the tappets. Hard thin coatings applied by the PVD or CVD method exhibit a high degree of both hardness and heat resistance, and are capable of improving wear resistance and reducing friction. They are commonly used for tools and molds but because of poor adhesion with the substrate, the coating tends to peel off easily, which has hindered the use of hard thin coatings for engine parts that must operate under severe sliding conditions. However, recent technical improvements have made hard thin coatings more adhesive and more tough, and they are recently expected to be applied to engine parts. In a motorcycle engine, the tappets convert the rotating motion of the cams to the pitching motion of the valves, and they slide with the cams at a high speed under high pressure. Reducing the friction between the tappets and the cams would increase the power of the engine. We studied a way to reduce the coefficient of friction between tappets and cams by applying a hard thin coating of DLC, MoS2, CrN, or TiN to the tappets. We investigated the adhesion of the coatings with a scratch test and their tribological properties with a ball-on-disk test. We then examined their durability with an engine stand test. We concluded that a tappet coated with DLC effectively reduces friction at the cam and tappet interface and is sufficiently durable to be applied to actual motorcycle engines.


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    Titel :

    Applying hard thin coatings to tappets to reduce friction


    Weitere Titelangaben:

    Auftragung von harten dünnen Beschichtungen auf die Ventilstößel von Motorrädern zur Reibungsverringerung


    Beteiligte:
    Kodai, A. (Autor:in) / Mori, T. (Autor:in)


    Erscheinungsdatum :

    2001


    Format / Umfang :

    8 Seiten, 11 Bilder, 2 Tabellen, 4 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Applying hard thin coatings to tappets to reduce friction

    Kodai,A. / Mori,T. / Inukai,T. et al. | Kraftfahrwesen | 2002


    APPLYING HARD THIN COATINGS TO TAPPETS TO REDUCE FRICTION

    Kodai, A. / Inukai, T. / Mori, T. | SAE Technical Papers | 2001


    Camshaft tappets

    Engineering Index Backfile | 1955


    Valve tappets

    Engineering Index Backfile | 1945


    Hydraulic valve tappets

    Brown-Waring, R. | Engineering Index Backfile | 1953