You hear it in everyday conversations — “Let’s not reinvent the wheel.” It is meant to convey the idea that some things are immutable. They are what they are and always will be. Like the wheel. But the folks at Continental have taken a second look at the traditional wheel for automobiles and decided there really might be a better way. They call it the New Wheel Concept. Here’s how it works.
First, Continental separates the wheel itself into two components — an outer rim that carries the tire and an inner truss that is permanently bolted to the hub and carries the brake disc and caliper. Anyone who has ever changed brake pads knows two things. One, it’s a difficult job. Two, it often means replacing the brake rotor. That’s when it turns into a miserable job involving lots of sockets, a few skinned knuckles, and an advanced vocabulary not suitable for impressionable youngsters.
In almost every disc brake system used today, the brake caliper is bolted to the hub and mounted outside the brake disc. Considering it is being asked to slow a two ton automobile moving at highway speeds to a complete stop in a matter of seconds, the disc itself is rather small. It has to be to allow enough room between the disc and the rim of the wheel for the caliper.
Those crafty folks at Continental asked, “What if we made the brake disc much larger in diameter and mounted the caliper inside it near the hub? And what if we made a truss-like carrier for the wheel rim that is permanently bolted to the hub and we bolted the brake disc to the truss?” Voilà, the New Wheel Concept was born. It is intended primarily for small to medium size electric cars.
“In EVs, it’s crucial that the driver expends as little energy as possible on the friction brake,” says Paul Linhoff, who heads up brake development in Continental’s chassis & safety unit. “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.”
Key to the New Wheel Concept is the use of aluminum for both components of the wheel, the brake caliper, and the brake disc itself. One of the ongoing issues with conventional brakes is the accumulation of rust on the disc. That coating of rust can significantly degrade braking performance, which has serious implications in situations where automatic emergency braking systems are activated. “Drivers want to be able to rely on a consistent braking effect — and too much rust on the brake disk in particular can really make this difficult,” Linhoff emphasizes.
Aluminum is lighter in weight than traditional steel wheels and conducts heat better. Light weight components are critical to achieving longer range in electric cars. An aluminum brake disc may seem counter-intuitive to shade tree mechanics, but the larger diameter means the brakes can use much lower clamping forces. That translates into the same stopping power with much less abrasion and therefore less wear.
With the advent of regenerative braking systems leading to more “one pedal driving,” the wear and tear on mechanical brakes is being reduced significantly. Continental expects its new aluminum brake disc to last the life of the vehicle. Brake pad changes will be less frequent as well.
“Because the brake disk is fixed on the outside and the brake engages from the inside, the brake caliper can be designed particularly light and stiff. The force is transmitted largely symmetrically into the center of the axle, and this has a favorable effect on the noise behavior of the brake,” says Linhoff. That’s another plus for the New Wheel Concept. Electric cars are quieter than conventional cars with internal combustion engines. Anything that enhances the sense of solitude for the passengers inside is an advantage. Continental will present its New Wheel Concept at the Frankfurt auto show in September.
Continental is one of the largest supplies to mainstream automakers and it is showcasing a number of new technologies, including and electrically heated catalytic converter that helps clean up diesel exhaust emissions, wireless charging systems, and advanced charging technology. In the world of auto manufacturing, suppliers are doing much of the heavy lifting when it comes to R&D for the cars of the future.
Source and photo credits: Continental