Friction dissipation in reciprocating internal combustion engines: cam tappet contact

The interest towards fuel consumption reduction in reciprocating internal combustion engines has achieved a key role starting from the first energy crisis during the 70’s. Even if in alternate phases, such interest had further increased during the following years assuming a fundamental role in the last years. The reason lies in the introduction of regulations that limit the emissions of carbon dioxide, as it belongs to the family of greenhouse gasses. A reduction of the friction dissipation reflects directly on consumption reduction and consequently in an improvement of emissions. The main goal of this research is to model the friction dissipation at the cam tappet interface. In this research an analytic model is proposed, it allows to estimate the dissipation due to friction with a complexity appropriate to that of the design phase and which allows to select between different design solutions in order to optimize the efficiency of the cam tappet interfaces. Model results are coherent with experimental results reported in literature.