Hyundai has received a US patent for a vehicle wheel that can change its aerodynamic shape while in motion. The system closes the openings between the spokes at high speed and opens them when necessary to direct air toward the brakes. The solution does not involve the wheel’s load-bearing spokes retracting or extending. Beneath them is a separate mechanism with a rotating central ring and several blades. When turned in one direction, the blades move behind the openings between the spokes and cover them. This gives the wheel a more enclosed surface, which may reduce aerodynamic drag.
When moved in the opposite direction, the blades retract behind the stationary spokes. The openings once again allow air to reach the braking system, which is important during city driving, prolonged descents, or situations in which the brakes generate more heat.
The patent describes various ways of activating the mechanism. These include electric motors, hydraulic and pneumatic drives. It also mentions a shape-memory alloy element that changes its length when electronically activated and can move the internal system into the closed position.
Once the drive is released, a spring or another elastic element can return the blades to their original position. The system can be controlled by a small electronic board mounted inside the wheel itself. The patent description also includes blades with a bent outer end connected to the rotating ring.
According to Hyundai, wheels and tires account for approximately 25% of a vehicle’s aerodynamic drag when driving on a highway. Reducing it could be significant both for fuel consumption and for the range of electric vehicles. A permanently closed wheel, however, limits airflow to the brakes.
For now, it has not been specified at what speed the mechanism would be activated or exactly how much it would reduce drag. Hyundai and Kia have not announced plans for series production.