A Methodology and estimation of Film Thickness in Elastohydrodynamic Lubrication

Cam and tappetare always under gigantic stresses which lead to wear and tear of the same. Hence it must be identified, estimated and minimized for prolonged and smooth running of engine. This paper describes an approach to estimate wear prediction in cam and tappet of diesel engines through force and wear analysis and which leads to estimation of minimum film thickness between cam and tappet. So that wear rate can be reduced up to certain extent. Through inertia forces accurate valuation of contact stresses has been done which imparts vital role in prediction of wear. Contacting loads and relative motions have been deduced from kinematic and dynamic analysis of valve gear train. Estimation of wear has been done by using Archard's wear model. For film thickness evaluation, DowsonHamrock's curve fitting formula has been used considering elastohydrodynamic lubrication. In this analysis, the flatfaced tappet has been used with Polydyne cam profile.