The invention is called Uni Wheel (stands for Universal Wheel Drive System), it allows you to more efficiently use the space inside the electric vehicle, install it on get a larger battery, experiment with the interior layout.
Uni Wheel is not a wheel motor, but an invention that is ideologically close to it, aimed at saving space inside an electric vehicle and optimizing its design. The essence of the idea is to move the gearbox working in conjunction with an electric motor inside the wheel. To provide the required range of angular speeds on the wheel, an electric motor usually only needs a single-stage gearbox, that is, in technical terms, this is a fairly simple device with a small number of parts.
Hyundai Motor Group engineers (which, we recall, includes the Kia company) not only placed the gearbox inside the wheel, but also endowed it with additional useful properties due to a unique design: it allows you to compensate for the movements of the axle shafts during suspension operation, which means that the drive elements and the suspensions can be made more compact and/or the range of ride height adjustment can be expanded.
Uni Wheel is designed in such a way that the drive axle axis should not be located strictly in the geometric center of the wheel, but “walks” while moving inside the perimeter of a rectangular window, the dimensions of which are selected based on the kinematics of the drive mechanism. The drive mechanism is planetary type: two multi-link carriers are connected to the sun gear, each of which has four gears installed, providing the required gear ratio.
To understand how the Uni Wheel works, it is better to watch the video published on the Hyundai Motor Group YouTube channel, although after watching it you may still have questions. Thus, the video does not show the brake mechanisms at all: the gearboxes will either displace them inside the electric vehicle or will be adjacent to them — then the wheel assembly will be quite bulky and heavy. It is also unclear whether the Uni Wheel allows you to completely get rid of CV joints — the video does not show how the mechanism works on a rotated wheel.
The theoretical advantages of the Uni Wheel are obvious: in conjunction with compact individual electric motors for each wheel, they allow you to free up the central space between the wheels of one axle — this space can be used to install additional battery cells, luggage or expand the interior. At the same time, the power electronics with wires still need to go somewhere — in the comparative image of the platform with traditional wheels and the platform with Uni Wheel wheels, the power electronics elements are shown only for the platform with traditional wheels.
Hyundai Motor Group reports that it has filed a lot of patents for the Uni Wheel and conducted a large number of full-scale tests, in which the gear wheel performed well. The innovative built-in gearbox is suitable for wheels ranging from 4 to 25 inches, but the South Korean company has not yet said when and on which production models we will see it.