Posted to News on 11th Sep 2020, 10:11
NSK develops ultra-high-speed ball bearings for EV motors
NSK has developed a new ball bearing that it says has ultra-high-speed capability and is well suited for use in the traction motors of electric and hybrid vehicles. As well as allowing electric motors to operate at higher speeds, the new bearing is also claimed to improve fuel economy (through reduced power consumption per unit distance), supporting an increase in vehicle range. Consumer concerns about range continue to drive the development of lighter, faster, higher output motors which in turn means electric motors are being subjected to increasingly higher speeds and performance demands says NSK.
Bearing rotation during high-speed operation can cause problems such as grease deterioration due to high operating temperatures, and this can lead to bearing seizure or failure. Higher speeds can also lead to the bearing cage becoming deformed or on occasion, destroyed by centrifugal forces. To help counter these issues, NSK says that its new bearing is filled with a proprietary grease that reduces heat generation at high rotational speeds, prolonging both grease and bearing life, and reducing the risk of seizure compared with conventional products. In addition, a newly developed cage is deployed with retainer tabs that are not only thinner and lighter, but reduce the potential for cage deformation or breakage. This design is supported by a new design of cage base (spine) together with a newly developed cage material made from high-rigidity resin, which offers further heat resistance at the high speeds found in EV motors.
The combination of proprietary NSK grease and newly developed cage enables bearing operation at dmN(1) = 1.4 million (1). To provide a practical example, this world-leading measure of rotational performance means one of NSK's new 35mm bore diameter bearings can operate reliably at speeds of 30,000 rpm, says the company. As a result of this advance in bearing technology, automotive customers can develop and implement electric motors that operate at significantly higher speeds. High motor output contributes to the utilisation of smaller motors, reduced vehicle weight and increased space for other components, such as more battery cells, for example. In turn, lower fuel consumption, extended vehicle range and/or improved comfort can be achieved. Looking ahead, NSK is continuing its development efforts and expects to announce bearings capable of dmN = 1.6 million by the end of 2020.
Note (1) dmN: A measure of bearing rotational performance. The product of bearing pitch diameter (dm) and rotational speed (N).
For further information please visit nskeurope.com.
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