Technology is moving fast these days, and while much of the focus with EV development is on batteries, other components are equally important. Take the power transmission, for example. Electric cars generally use a single-speed system that’s often referred to as direct drive, but they do still have a gearbox as well.
It’s just not as big as the one in an ICE car. This reduction gear mechanism is necessary to reduce the rotation of the traction motor, or all you’d be generating when hitting the accelerator would be white smoke from your tires. Hyundai has now figured out a way to move this component to the wheels of the car, freeing up space in the chassis.
Space is always at a premium in cars, and manufacturers like to reserve as much of it as they can for the comfort of passengers. EVs already offer an advantage here, as they can usually do away with a big transmission tunnel and enable vehicles to have a flat-floor layout.
But by also getting rid of a traditional reduction box, even more space is freed up. Of course, the power that turns the wheels still needs to be reduced, and the way Hyundai does this is what a clever concept (called Uni Wheel) does.
Instead of a conventional drive system with CV (constant velocity) joints, the company is utilizing the space within the wheel hub to fit a planetary gear configuration that takes care of the necessary gear reduction.
It involves a sun gear in the center, four pinion gears on each side, and a ring gear surrounding the setup. All that might sound complicated, but the images supplied with the press release make it quite easy to understand and also show the multilink mechanism that connects the pinion gears to each other.
Hyundai claims that its invention—especially when combined with electronic air suspension—offers plenty of suspension articulation, and enables a smooth and very efficient ride. The concept also allows for smaller electric motors to be used and for improvements in torque vectoring and steering stability.
The biggest benefit seems to be the space this frees up elsewhere, though. From more cargo space in the front trunk, to different cabin layouts that weren’t previously possible, the Uni Wheel layout frees up more possibilities for more compact and space-efficient cars and cabin layouts. Hyundai has filed numerous patents for the idea, and we may see it in production cars at some point in the not-too-distant future.