A Mixed Thermal Elasto-hydrodynamic Lubrication Model for Crowned Roller Contacts

Z. Liu¹, Y. Liu³, T. Nishino² and Q. Wang¹

¹Department of Mechanical Engineering, Northwestern University,

2145 Sheridan Road, Evanston, IL, USA

²Powertrain Division, Mazda Motor Corporation,

3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima 730-8670, Japan

³GM Powertrain, Pontiac, MI.

Much attention has been focusing on point contact, infinite-length line contact and finite-length cylindrical contact models for simulating lubricated contact interfaces. However, these models are not well applicable to the interfaces in rotary engines, cam-followers, bearing rollers and gear teeth, because the surfaces of these components are usually crowned.  This paper reports a mixed thermal elasto-hydrodynamic lubrication model for crowned roller interfaces, in which the Reynolds and the energy equations are coupled and solved to obtain the pressure distributions and evaluate the lubricant film temperature change. The discrete convolution and fast Fourier transform (DC-FFT) method is utilized to calculate the surface elastic deformation and the temperature rise. Several cases of crowned rollers were analyzed, and the results show that thermal effects cannot be neglected, especially for rollers with rough surfaces, and that the changes in the crown radius and the total load have a significant impact on both temperature and pressure. Parametric studies for roller geometry designs are conducted to minimize the pressure and the peak temperature.