Dynamic analysis for deep groove ball bearing under grease elastohydrodynamic lubrication

The dynamic characteristic of deep groove ball bearings for driving motors is one of the cores that affect the service performance of new energy vehicles. In order to offer guidance for the design and use of bearings, a three-dimensional dynamic characteristic analysis model of the deep groove ball bearing is established accounting for the effects of grease elastohydrodynamic lubrication (EHL) in the contact pair between rolling elements and rings. The grease-film stiffness and damping coefficients for each contact are calculated by proposing a model combining the grease EHL theory and free vibration theory, and explicit expressions are fitted and introduced to decouple the bearing dynamic simulation and the grease EHL calculation. The effects of grease, bearing operating conditions, and cage structural parameters on the bearing stability are examined. The results indicate that sufficient grease helps to improve the bearing stability. As the inner ring speed increases, bearing stability initially rises and then falls. In contrast, with increasing axial load or decreasing radial load, bearing stability improves. Moreover, as the cage pocket diameter or the cage thickness at inner bottom increases, bearing stability shows a trend of first rising and then falling, while an increase in the beam width of the cage leads to improved bearing stability.