Every watt counts

Increasing the range of electric vehicles with high-efficiency wheel and transmission bearings.

Across the globe, there are more and more electric cars on the road. In Germany, for example, one in five new cars with battery-electric drive was sold in July 2023. Despite this, electric vehicle (EV) range is a commonly cited issue, with every second EV or hybrid driver in Europe reporting it as one of the top three concerns they have with their vehicles, according to Shell’s 2023 EV Driver Report.

The motor isn’t the only thing drawing on the battery, either. Especially in winter, creature comforts such as heating also use electricity, at the expense of range. Motion technology pioneer Schaeffler Group is doing a lot of work in this space, explains Matthias Zink, CEO Automotive Technologies: “Schaeffler is developing solutions to combat range anxiety. Our smart technical solutions and wide range of components and systems for fully electrified powertrains improve the day-to-day practicality of electric vehicles by reducing power consumption and increasing range.”

HIGH-EFFICIENCY BEARING SOLUTIONS

Just like conventional internal combustion engine (ICE) vehicles, EVs needs bearings to function. That being so, one of the key ways of boosting range in EVs is to reduce frictional losses, where energy that would otherwise be used for powering the vehicle is lost as heat through bearing friction. Schaeffler has developed several bearing solutions to counter this. The company’s highly-efficient transmission bearings are designed to reduce friction significantly, saving about 50W of energy compared to conventional bearing solutions which translates directly into extra range. In addition, the company’s EV transmission bearings are specially adapted for the high rotational speeds of electric-drive transmission input shafts and therefore ensure optimal load accommodation.

“Innovative bearing technologies are a core part of our product DNA and underpin the success of our Automotive Technologies division,” says Zink. “Schaeffler is looking to fit its efficient and high-precision bearing solutions in electrified powertrains and chassis systems, as well as conventional powertrains, to further enhance these systems and make them more sustainable.”

In the pursuit of even more range, Schaeffler has developed its TriFinity wheel bearing designed for use in electrified powertrains. The bearing is designed to guide and support the drive shafts and axles ensuring that the wheels can turn with minimal resistance, even under high mechanical load. Wheel bearings are subjected to immense forces during normal driving operation and are constantly in motion, rotating some 100 million times every 180,000km travelled. Schaeffler’s TriFinity wheel bearing is capable of reducing frictional losses by a huge 67% compared to conventional bearings, representing a saving of more than 200W or 20km of additional range in a fully charged electric SUV with a 120-kWh battery capacity. Alternatively, in winter that extra 200W could be used for heating the driver and passenger seats with no loss of range.

The triple-row TriFinity wheel bearing also offers a weight saving of about 10% over standard double-row ball bearings for the same dimensions, and offers a longer service life. As well as that, the bearing provides over 20% greater stiffness, meaning it can transfer greater axle loads which is a key advantage in heavier EVs. The combination of the TriFinity bearing with Schaeffler’s face spline technology allows downsizing solutions in the form of wheel bearing units with smaller diameters, reduced bearing and seal friction, optimised bearing weight, and a smaller carbon footprint. For the same dimensions, the clearance-free face spline technology reduces bearing weight while enabling the component to transmit up to 50% more drive torque. It also makes the bearing easier to mount and reduces noise emissions in EVs.