Hyundai and Kia debut new EV drive system
Korean duo’s novel new Uni Wheel promises to save space and energy while enhancing torque vectoringHyundai and Kia have revealed what they think could be the future of electric vehicle drivetrain packaging in the form of their new Universal Wheel Drive System, aka the Uni Wheel.
The concept revolves around the reimagining and consolidation of EV drivetrain componentry in that the main drive system components are located within the usually vacant space within the wheel hub.
“In internal combustion engine vehicles power is transmitted from the engine through the transmission and to the wheels via drive shafts and constant velocity (CV) joints,” engineers said.
“In EVs, the engine and transmission are replaced by a motor and reduction gear, but the final method of transmission to the wheels is the same.
“Uni Wheel opens new possibilities and enables a flat-floor configuration by moving an EV’s reduction gear inside the wheel hub, locating a compact individual motor close to each wheel, reducing the length of the drive shafts.”
The primary benefit of such a design is the radically increased real-estate which can be repurposed or capitalised on for bigger and roomier passenger compartments and or load beds within the context of purpose-built vehicles.
Looking further ahead, however, there’s also scope for huge power, performance and traction gains, given all-wheel drive and 4x4 applications of the Uni Wheel will pack four motors instead of the typical two, meaning each wheel will have its own motor and can be individually controlled or adjusted.
Hyundai and Kia are also claiming significant gains in powertrain efficiency both in terms of energy consumption and power transmission, thanks to the system’s planetary gear configuration.
“Uni Wheel uses a special planetary gear configuration consisting of a sun gear in the centre, four pinion gears on each side and a ring gear surrounding this arrangement,” engineers said.
“Power generated by the motor is transmitted to the sun gear, which in turn engages the pinion gears to rotate the ring gear. This is connected to the wheel to drive the vehicle.
“Uni Wheel’s pinion gears are connected to each other to form two linkages, and this multi-link mechanism enables Uni Wheel’s multi-axis movement to allow a wide range of suspension articulation.”
The tech is also scalable and can be applied to anything from family vehicles and trucks through to wheelchairs, bicycles and delivery robots, but a timeline for commercial release is yet to be announced.
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