Ball bearing increases range of electric vehicles
Ball bearings are either open on the sides ─ known as open bearings ─ or have seals made from rubber. These sealed bearing units keep contamination away from the balls and the raceways of the bearing rings. This translates into less wear and, thus, a longer service life. The drawback of this approach however, is the higher level of friction in the bearing, which corresponds to valuable energy being lost. In open-style bearings, although this friction is reduced, the bearing units break down more quickly due to the lack of protection from contamination. A real dilemma. With the high-performance ball bearing with integrated centrifugal disc, Schaeffler has developed a unique bearing that combines the benefits of an open bearing with those of a sealed one. As such, significantly less energy is lost in the bearing in the form of friction. “Less friction means that drive energy is used more efficiently. This, in turn, lowers emissions and improves the range of electric vehicles,” says Dr. Dieter Eireiner, Head of the Bearing Business Division at Schaeffler.
What really makes the new bearing stand out is that the rubber seals that are normally attached firmly to the outer sides of the bearing are replaced with a specially designed centrifugal disc integrated in the inner ring. This disc keeps contamination out ─ similar to a sealed bearing. Since the disc rotates freely, however, the bearing generates about 80 % less friction than with conventional seals. The result is a CO2 reduction of up to 0.3 grams per kilometer per vehicle. Reducing losses of up to 30 watts per bearing can also improve the range of electric vehicles by up to 1%.
The centrifugal disc bearing also lasts considerably longer. Compared to open bearings, the service life increases by a factor of up to 10, whereas the unit lasts twice as long as conventional sealed ball bearings. This, then, means that bearing and transmission assemblies can be downsized in the future, thereby conserving material and weight.
The bearing weighs just 300 grams and is between 5 and 10 centimeters in diameter, depending on the application. The first automotive manufacturers have been using the new ball bearing in production hybrid and double-clutch transmissions since 2021, and Schaeffler is collaborating with other manufacturers in development projects moving forward to a volume production launch. The company is likewise transferring the patent-pending technology to ever new application areas in its bearing business, including dedicated electric vehicles.