Abstract
To design good fuel efficient engines it is necessary to minimize engine friction losses. Understanding the effect of different design parameters on engine friction is therefore critical. Many engine design parameters which affect the engine friction are fixed at the design architecture stage itself and it is difficult, often impossible to modify these parameters in later stages of engine development. Therefore, the objective of the present work is to develop a friction model which can be used in engine architecture phase and also predict engine friction accurately. In this paper, a physics based engine friction model is developed using simplified friction equations with coefficient of these equations obtained from non-linear regression analysis of test data. The technical approach of the friction model can be briefly summarized as follows. First, the key design parameters in each component/sub-component are studied and physics based equations as a function of design parameters are derived for each sub-component. The multiple regression technique is then used to determine the coefficients in each engine component friction equation to fit the test data with minimum errors. The developed friction model was used to predict friction for different engines and the predicted values correlate well with test data.