World-leading Performance for EV Motors: NSK Bearings Step-up to Meet the Challenge of Ultra-High-Speed Rotation

Many companies are engaged in a variety of initiatives to realize a sustainable society. The automotive industry has made great strides in popularizing the electric vehicle (EV), which has a low environmental impact, but there are still significant challenges to achieve widespread adoption. Today, we talk to NSK engineers about the challenges in developing bearings for EV, and how bearings are helping take EV technology to the next level.

What do EV need from component makers?

IwanagaThe new movement in automotive technology called CASE* has created a push in the automotive industry to electrify the constituent components of each sub-system in vehicles. Among the various types of EV, which include fully-electric vehicles and plug-in hybrids, there is one common challenge: consumers want to be able to drive longer distances on a single charge. Maximum range depends on vehicle weight, efficiency, and battery capacity. Accordingly, a key task for the industry is to downsize components, thereby reducing weight or creating space for additional battery cells. The motor is no exception. By reducing the size of the motor, the vehicle becomes lighter, and it can travel farther using less power. However, when you shrink the size of the motor, it cannot produce the same amount of power if it keeps rotating at the same speed as before. So as the motor gets smaller, the only thing that we can do to maintain power is to increase the rotational speed. Not only does this require us to reduce the size of the bearings and other components used inside the motor, but it also requires the components to be able to handle rotation at much higher speeds.

ShimokawaFrom an environmental perspective, making the motor and other EV components smaller and lighter enables us to utilize the freed-up space for additional battery cells. This improves fuel and power consumption and increases the vehicle's running distance on a single charge, resulting in EV appealing to more consumers and ultimately leading to a positive contribution to the environment, such as through lower EV life cycle CO2 emissions.

Combining multiple new technologies was no easy task, but overcoming the challenge is how we delivered a world-leading product

IwanagaNSK has experience developing products to support motors of increasingly high speeds, but our new development team, specializing in next-generation high-speed products, was launched two years ago. The first product we developed was the Ultra-High-Speed Ball Bearing for EV Motors announced in March of this year. At the time of announcement, this bearing was the world's fastest grease-lubricated bearing for use in EV motors (March 2020, based on in-house findings), with a dmN* that is about 2.5 times higher than that of conventional products.

*dmN: An indicator expressing a bearing's rotational performance calculated as bearing pitch diameter (dm) x rotational speed (n).