Hyundai and Kia have unveiled a new type of electric drive system that has the potential to free up considerable space in electric vehicles.
Called the Universal Wheel Drive System, or Uni Wheel for short, the system moves the electric motor adjacent to the wheel, and the reduction gear inside the wheel, freeing up space between two wheels where the motor normally sits.
Such a design gives most of the packaging benefits that in-wheel motors deliver, but without the durability issues of having the actual motor mounted inside the wheel.
The Uni Wheel sits where you would normally find a CV joint, a component that the Uni Wheel replaces with a planetary gear set with a central sun gear, four pinion gears on each side, and a surrounding ring gear connected to the wheel. The electric motor spins the sun gear, which in turn engages the pinion gears to rotate the ring gear and connected wheel.
A linkage enables the pinion gears to move and follow the movement of the wheel as it drives over a road's surface, something that allows torque delivery to be constant, while still letting the wheel move freely. This helps improve efficiency as well as vehicle control, according to Hyundai.
The design is scalable and modular in nature, meaning an individual Uni Wheel can be used for each wheel in an EV, allowing for highly precise torque vectoring. To further aid handling, the Uni Wheel can be combined with adjustable air suspension that can lower the vehicle during high-speed driving, or raise it for rough terrain.
Hyundai and Kia are still conducting durability tests for the Uni Wheel but have already filed for eight patents with intellectual property offices in the U.S., South Korea, and Europe. The automakers are looking to use the technology not only in future EVs but all forms of mobility that rely on driven wheels.
Hyundai has also previously shown a system known as the e-Corner, which combines suspension, steering, driving, and braking functions in a package small enough to fit in the wheel hub of a conventional vehicle. The e-Corner enables a wheel to be turned up to 90 degrees, allowing a car to drive sideways.