Kia and Hyundai unveil their integrated, wheel-mounted powertrain solution for battery-electric vehicles.
The sister automakers’ Uni Wheel powertrain is not the first to market; companies including Lightyear, Continental, GKN Automotive, Schaeffler and Nissan have fielded similar technologies. However, the mass production potential of Kia and Hyundai could see their system among the first to make it to widespread general use.
Like the others, Uni Wheel enables a flat-floor configuration by moving the vehicle’s reduction gear inside the wheel hub, locating a compact individual motor close to each wheel, reducing the length of the drive shafts. It also can be used in a wider range of vehicles such as the Hyundai Group’s planned Purpose-Built Vehicles utility vehicle platforms.
The system uses a planetary gear configuration consisting of a sun gear in the center, four pinion gears on each side and a ring gear surrounding this arrangement. Power generated by the motor is transmitted to the sun gear which 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 enabling multi-axis movement claiming a wide range of suspension articulation. When combined with electronic air suspension, ride height can be adjusted according to the driving situation: increased to stabilize the vehicle on rough roads or decreased for high-speed driving to improve power and stability.
Kia and Hyundai have applied for and registered eight patents related to Uni Wheel in South Korea as well as the U.S. and Europe.