Temperature Analysis And Life Estimation Of The Third Generation Wheel Hub Bearing Unit

In order to coordinate the better development of automobile, hub bearing unit as an essential part of the car, has carried out much change. Now, the characteristics of hub bearing unit have become a key factor to determine the overall performance of the car. As hub bearing working on a high speed rotation condition, much friction heat will generate. If the heat generated can not be effective allocation, it will accumulate continually in the contact zones of the bearing. Bearing lubrication situation will deteriorate and lead to the bearing premature failure. So the friction power loss and temperature field analysis has a great significance to the wheel hub bearing unit. It is helpful to reasonable design and proper use of bearings, and also be used for bearing failure analysis. Furthermore, hub bearing is arranged on the wheel hub. The pavement conditions have great effect on the wheel bearing in the running process of the car. Because of the complexity of the use conditions, the reliability and service life can been evaluated and given the reasonable forecast based on the durability test loading spectrum. Test load spectrum should been formulated according to the actual situation of the vehicle, and combined with the characteristic of vehicle. The reasonable and effective load spectrum is a key to durability simulation test of the hub bearing.In this paper, the temperature field analysis and life estimation based on the load spectrum in different conditions are carried out about the third generation hub bearing (double row angular contact ball bearings and double row taper roller bearings). Firstly, the complete mechanics balance equations considering the external loads and internal deformation factors are established based on the Hertz contact theory and quasi static method of bearing. It provides the basis for the following thermal analysis and life estimation. Then the numerical method and example verification according to the mechanical equilibrium equations are carried out. Secondly, the friction loss changes under different working conditions (axial load, radial load, rotation speed and turning moment) are analyzed and the power loss generated in the internal friction parts using local method is calculated based on the heat transfer theory. Using the ANSYS software to develop the heat transfer model of hub bearing, the power loss of hub bearings and the friction heat phenomenon is analyzed in detail. Then the simulation test load spectra based on the car type and operation conditions is established and the fatigue life on each kind of conditions is also calculated. The influence of pre-tightening force, lateral acceleration, load eccentricity and radius of the tire on the wheel hub bearing unit comprehensive life is analyzed respectively. Finally, the durability assessment and temperature rise are compared with the test dates. It proves that the method is feasible, and it has practical reference value.The researches results can be directly used for the distribution of temperature field and life estimation reference of the wheel hub bearing unit. And it makes the enterprises possess the ability of independent development and enter the middle and high-end car market.