First Page Design
Site Theme
We love weird new engineering concepts here at Ars, and today we have an especially attractive one in the bed of electric cars. It’s called the Uni Wheel and it’s designed by Hyundai and Kia as a way to revolutionize the design of an electric vehicle’s powertrain to make more efficient use of space. In fact, automakers say it’s not just for cars: the new powertrain formula works with wheels from 4 inches to 25 inches.
For EV enthusiasts of a certain level, there’s something a little inefficient about the way virtually every EV powertrain is presented.
It’s not the middle battery, though: while it’s bulky and increases the overall height of EVs, it makes sense for weight distribution, other people who run on structural carbon fiber batteries have other ideas about it. The propulsion unit of an electric vehicle, a bulky element comprising the electric motor, gears, and usually the power electronics. These take up space between the axles and must be grouped together.
One option is to mount the electric motor of each drive wheel on the wheel hub. The Lohner-Porsche Mixte Hybrid used this technique in 1900, but it was largely rejected by car brands still struggling to progress: Lordstown, Endurance. and Aptera, partly because it had deleterious effects on unsprung weight and partly because it was not stalled. It means that the engine reports the same bumps and jolts as the wheel.
Uni Wheel does something different. Each drive wheel still has its own electric motor, but it’s fixed much closer to the suspension, freeing up more area between the axles (which can be used for more battery modules). The challenge with this so far has been that the traditional CV joints can’t cope with the angles that would be necessary, given the shorter driveshaft from the engine to the wheel.
Then, instead, the CV joint, driveshaft and gearbox are moved to a new unit fixed on the wheel. It is a planetary gear formula that transfers traction from the motor to the wheel, but with a diversity of multiple links between the sprockets. which allows the drive shaft to be articulated in a wide variety of movements.
Beyond electric passenger vehicles, Hyundai and Kia say the Uni Wheel’s articulation and ability to accommodate smaller wheels can allow a wheelchair or multi-wheeled robot to climb stairs “as smoothly as an escalator. “
Like many strange new engineering concepts that catch our eye, the Uni Wheel is still in the early stages of development, so there’s no guarantee we’ll see it in production anytime soon. But any of the automakers say they continue to refine the design, with expected innovations in efficiency, cooling, lubrication and durability.
Join the Ars Orbital Transmission email to receive weekly updates in your inbox. Sign up →