In a bid to revolutionize electric vehicles (EVs), Korean automakers Hyundai and Kia have introduced their groundbreaking Universal Wheel Drive System, aptly named ‘Uni Wheel.’ This innovative design reimagines the internal architecture of EVs by cleverly relocating key drive system elements into the previously unused space within the wheel hub.

The Uni Wheel system not only significantly enhances the overall efficiency of the vehicle but also liberates a considerable amount of internal space, presenting a departure from conventional drive system structures. This approach holds promise for the development of future mobility products, including Purpose Built Vehicles (PBVs), optimized for various applications.

The technology was unveiled at the Uni Wheel Tech Day in Seoul on November 29, where Kia and Hyundai Motor showcased their commitment to innovation. The companies have already applied for and registered eight patents related to Uni Wheel’s design and technology in South Korea, the United States, and Europe.

Uni Wheel’s unique design utilizes a planetary gear setup, featuring a central sun gear surrounded by four pinion gears on each side, enclosed by a ring gear. This design allows for the transmission of power from the motor to the wheels, ensuring nearly constant efficiency regardless of wheel movement.

Unlike traditional drive systems with regular constant velocity (CV) joints, Uni Wheel maintains high efficiency and durability on uneven surfaces, providing enhanced ride comfort, especially on bumpy terrains. When coupled with electronic air suspension, the system dynamically adjusts ride height based on driving conditions, stabilizing the vehicle on rough roads and improving power and stability during high-speed driving.

By relocating the reduction gear to the wheel hub, Uni Wheel achieves a notable reduction ratio, resulting in significant torque output and a more compact electric motor. This design also facilitates independent control of up to four electric drive units, enabling unprecedented torque vectoring for enhanced dynamic performance, steering, and driving stability.

Uni Wheel’s innovations extend beyond performance improvements, liberating previously untapped space within the vehicle. By downsizing the electric motor and relocating drive system components to the wheel hub, additional space is made available for various purposes, such as expanding cargo room or creating a front trunk (‘frunk’).

This newfound space proves valuable for maximizing passenger space, addressing a common challenge faced by traditional EVs with low-placed batteries. Uni Wheel optimizes battery packaging, ensuring minimal reduction in passenger space. This feature is particularly beneficial for Personal Battery Vehicles (PBVs), where a flat-floor design is crucial to maximize interior space.

Uni Wheel’s adaptability extends to various EV types, from standard passenger vehicles to high-performance models. The system’s versatile design can also be applied to other types of mobility devices, such as wheelchairs, bicycles, delivery robots, and vehicles of different sizes.

Kia and Hyundai Motor are currently conducting tests on Uni Wheel to ensure stability, efficiency, and durability. Ongoing tests aim to refine its development, with a commitment to further enhancing efficiency through adjustments to the reduction gear ratio and upgrades to the lubrication and cooling system.

By Impact Lab