An Improved Method for Friction Power Loss of DGBB Considering the Clearance and Axial Force
Fuchun Jia, Chunruo Shi, Rui Guo, Lijun Li, Changheng Lu, Jianda LiIntroduction:
Deep-Groove Ball Bearings (DGBBs) are widely used in electric vehicle reducers. However, the axial force generated by helical gear meshing may cause relative displacement between the inner and outer raceways in bearings with clearance, altering the contact state between the balls and raceways and complicating the prediction of friction power loss. Therefore, an improved analytical model for DGBB power loss prediction is proposed.
Methods:
An improved analytical model for predicting friction power loss in deep-groove ball bearings is developed based on point-contact Elastohydrodynamic Lubrication (EHL) theory, integrating bearing kinematics, load distribution analysis, and rolling/sliding friction calculations. Bearing clearance, applied load, operating conditions, surface roughness, and lubricant properties are comprehensively incorporated into the model.
Results:
The proposed model accurately predicts the contact characteristics and friction power loss of the balls by considering the effects of clearance, revolution, rotation, and centrifugal force. The predicted variations in friction power loss are consistent with the corresponding changes in load distribution and rolling and sliding kinematics.
Discussion:
The results indicate that variations in oil-film thickness and contact pressure induced by operating speed and applied load significantly influence friction power loss. Both surface roughness and lubricant viscosity increase friction power loss, with the latter having a greater influence, leading to a maximum increase of 10.59 W within the investigated range.
Conclusion:
The improved DGBB model proposed in this study provides insight into the mechanism underlying bearing friction power loss and offers an effective, practical tool for predicting power loss in high-speed DGBBs.