In conformity with consumers’ demands and environmental protection requirements, vehicle manufacturers look for increasingly small and light components, to increase vehicles’ autonomy for each recharge. Consequently, transmission bearings, especially in electric motors, are subjected to higher and higher speed and performance requisites.
The previous generation of very high-speed ball bearings for EV motors was characterized by speeds of 1.4 million dmN and significant improvements in the cage and in the technology to increase their mechanical strength. With the third generation, NSK has aligned the solution to the demand for bearings able to reach even higher speeds. Besides the rotation at 1.8 million dmN (with the 28.5% increment), the new bearing is provided with a cage with optimized topology (OT). This process has allowed optimizing the material distribution inside the design space, with the target of obtaining the highest product performances. In the new bearing, the topology optimization has allowed maximising strength and minimizing weight, eliminating the parts that do not contribute in the strength and stiffness of the cage, so obtaining the optimal cage shape for high-speed rotation. The cage, made with a new resin with high stiffness degree, was designed in very short times exploiting a forefront simulation technology to assess its performances and production modalities.
Moreover, NSK lubricates these bearings with a purposely developed grease that reduces the resistance at high speeds and the consequent heat generation, extending the duration of grease and bearing and decreasing the seizure risk.