Bearings
Copes with extremely high speeds
NSK's third and latest generation of ultra-high speed ball bearings for electric vehicle motor bearings achieve a speed capability of over 1.8 million dmN. This makes them the world's fastest grease-lubricated deep groove ball bearings used in automotive electric drives. They contribute to higher range with one battery charge and to the design of compact electric drive systems with high line density.
Higher range, more compact drives, lower weight: these are central trends in the development of electric vehicles. Car manufacturers and suppliers are therefore working on more powerful motors with very high speeds that achieve higher efficiencies.
Motor mountings must also keep pace with this development. The second generation of ultra-high-speed ball bearings, which NSK had developed especially for automotive electric drives, already achieved a speed suitability (pitch circle diameter dm x speed N) of 1.4 million dmN. With the third and latest generation, which NSK is now presenting, the target mark of 1.8 million dmN will be reached. This corresponds to an increase of 28.5%.
This increase in performance was made possible because the developers consistently used the concept of topology optimisation, among other things in optimising the cage. By using this method, it was possible to maximise the strength of the cage and minimise the weight at the same time by saving material wherever it does not contribute to the durability or stiffness of the cage. In this way, the optimum cage shape for high speeds was achieved - and with a very short development time, because NSK used state-of-the-art simulation technology to test the cage's performance and already determined the production procedures during these tests.
The cage is made of a new high-performance polymer that is characterised by high rigidity and deforms only slightly at very high speeds compared to conventional materials. In addition, the bearings are filled with a special grease that enables a very low frictional torque. This reduces heat generation, which extends both the life of the grease and thus that of the bearing, and minimises the risk of bearing failure.
With the latest generation of EV deep groove ball bearings, NSK's customers can develop electric drives that operate at significantly higher speeds. This allows them to achieve higher motor outputs as well as higher efficiency (i.e. lower power consumption per distance travelled), as well as greater vehicle range. The higher engine speeds also allow the use of smaller engines. This reduces the vehicle weight and the available space can be used for other components - such as more battery cells - or for a larger vehicle interior.