Continental rethinks the wheel—and the brake—for electric cars

August 25th, 2017
by The Feeder

Enlarge (credit: Continental)

When it comes to making a car slow down, for the last few decades pretty much every car on the road has used the same idea: a brake disc mounted to the axle with calipers that press high-friction pads onto the disc’s surface, slowing its rotation. It’s a tried-and-tested formula, one that car makers adopted from the aerospace industry as a better solution than the venerable drum brake. But the boffins at Continental (the tire company) have been rethinking the standard way of doing things, specifically in the context of small and medium-size electric vehicles. Enter the New Wheel Concept.

The focus on EVs is logical, since in their case deceleration is often achieved via regenerative braking using the electric motor instead—at least on the driven wheels. Obviously, EVs can’t ditch the conventional brake, there needs to be redundant system for situations when regenerative braking isn’t possible like when the battery is full and can’t accept more energy. A consequence of using regenerative braking is that the friction brakes get much less use than in a conventional car, so they tend to last a lot longer. But there is a downside: a buildup of rust that can impair their performance when you need to use them, according to Continental. (This is only an issue with cast iron brakes, but we’re not aware of many hybrids that use carbon ceramic discs outside of the hypercar crowd.)

“In EVs, it’s crucial that the driver expends as little energy as possible on the friction brake,” said Paul Linhoff, Head of Brake Pre-Development in the Chassis & Safety Business Unit at Continental. “During a deceleration, the momentum of the vehicle is converted into electricity in the generator to increase the vehicle’s range. That’s why the driver continues to operate the brake pedal—but it certainly doesn’t mean that the wheel brakes are active too.”

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