Thermal Characteristics of Water-Lubricated Ceramic Hydrostatic Hydrodynamic Hybrid Bearings

The heat caused by the shear of oil films of hydrostatic hydrodynamic hybrid bearings leads to decreasing of bearing clearance and even seizure especially at high speeds, which limit the speed of bearing and the DN value. Compared with metal materials widely used in hydrostatic hydrodynamic hybrid bearings, ceramic materials have low coefficient of thermal expansion. Hence, in this study, ceramic bearing bushes with low coefficient of thermal expansion are employed to alleviate the decrease of bearing clearance due to the heat of oil film. And the change of bearing clearance and seizure temperature of the traditional metal bushes are also compared with one of the ceramic bushes. Firstly, a test rig for water-lubricated ceramic hydrostatic hydrodynamic hybrid bearings is built up, on which the result of simulation is verified and the boundary conditions of inlet and outlet temperature of bearings are tested for simulation. Secondly, the temperature rise, the thermal deformation, the bearing clearance and the seizure temperature of ceramic bushes (silicon nitride, aluminum oxide and silicon carbide) and a metal bush of tin bronze are investigated and compared through finite element method. The results show that the bearing’s working temperature is increased by using ceramic bearing bushes. And, compared with the bearing bush of tin bronze, the maximum working temperature of the bearing bush of silicon nitride, aluminum oxide, silicon carbide is improved 21.7, 27.2 and 30.7 %, respectively.