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Hyundai Motor and Kia unveil 'Uni Wheel' Drive System

Kia Corporation and Hyundai Motor Company have introduced the revolutionary Universal Wheel Drive System, known as ‘Uni Wheel,’ at the ‘Uni Wheel Tech Day’ in Seoul, Korea. This innovative vehicle drive system is set to transform the design of future mobility devices.

Uni Wheel is a functionally integrated wheel drive system that enhances the interior space of electric vehicles (EVs) by relocating the main drive system components to the vacant space within the wheel hub. Kia and Hyundai Motor have devised a completely new structure for the drive system.

In traditional internal combustion engine (ICE) vehicles, power transmission involves the engine, transmission, drive shafts, and constant velocity (CV) joints. Although EVs replace the engine and transmission with a motor and reduction gear, the final wheel transmission method remains similar.

Uni Wheel introduces new possibilities by placing an EV’s reduction gear inside the wheel hub, positioning a compact individual motor near each wheel, and reducing the length of the drive shafts. This groundbreaking system significantly increases interior space compared to conventional drive systems, paving the way for future mobility products optimized for various applications, including Purpose Built Vehicles (PBVs).

Advancements in electrification, autonomous driving, and connectivity technologies are reshaping mobility products into functional living spaces. Kia and Hyundai Motor’s emphasis on space utilization in future vehicle architectures aims to enhance customer value and deliver richer user experiences.

Uni Wheel incorporates a special planetary gear configuration, featuring a sun gear in the center, four pinion gears on each side, and a surrounding ring gear. The power generated by the motor is transmitted to the sun gear, engaging the pinion gears to rotate the ring gear, which, in turn, drives the vehicle’s wheel.

The pinion gears in Uni Wheel are interconnected, forming two linkages that enable multi-axis movement, allowing a wide range of suspension articulation. This innovative design minimizes efficiency and durability issues associated with conventional drive systems when traveling over uneven surfaces, ensuring high durability and ride comfort.

Uni Wheel’s high reduction ratio, achieved by moving the reduction gear to the wheel hub, delivers significant torque output and allows for a more compact electric motor. With independent control of up to four efficient electric drive units, Uni Wheel facilitates unprecedented torque vectoring, enhancing dynamic ability, steering, and driving stability.

The Uni Wheel concept liberates previously unavailable space within a vehicle. By relocating drive system components to the wheel hub and downsizing the electric motor without compromising performance, the extra space can be utilized for additional cargo room or innovative interior layouts in the era of fully autonomous driving.

The optimized battery packaging offered by Uni Wheel minimizes the loss of passenger space traditionally associated with low-mounted EV batteries. This feature is particularly beneficial for PBVs requiring a flat-floor design to maximize interior space.

Uni Wheel’s flexibility extends to various types of EVs, including regular passenger and high-performance EVs, as it can implement the same powertrain and reduction gear functions required for conventional EVs.

Beyond vehicles, Uni Wheel’s adaptability makes it suitable for other mobility devices, such as wheelchairs, bicycles, and delivery robots. Uni Wheel can be scaled to accommodate wheel sizes ranging from four inches to 25 inches or more. Its ability to move the rotation axis of the wheel opens the door to creating personal mobility forms capable of smoothly climbing stairs, similar to an escalator.

For additional information and detailed visual representations of the Uni Wheel drive system can be found here: