Greases for electric vehicle motors: thickener effect and energy saving potential

Electric vehicle motors in e-drivetrain are equipped with grease-lubricated bearings operating at both low and high speeds with frequent speed changes. The grease-bearing system must secure a long lifespan and low frictional torque to improve efficiency and sustainability. The present paper focuses on the influence of two types of thickener, lithium complex and polypropylene, on the grease lubrication performance under conditions typical for e-motors. The comparison of both thickeners is performed in terms of friction torque and energy consumption in eight long-duration experiments (337 hr). The results show that the polypropylene thickener provides 21.5% lower energy consumption compared to the lithium complex. Changes in grease rheology and degradation in the tests are analysed and correlated with the grease lubrication performance.