Michelin unveiled its electric drive system for the future at the recent Paris Motor Show. Named the Michelin Active Wheel, the system integrates a drive motor, electrical active suspension components, and a brake disc in a single wheel. The system is designed to provide either two- or four-wheel drive, according to OEM requirements.
Two cars were on display in Paris fitted with the Active Wheel: the Venturi Volage two-seat coupe, featuring a four-wheel-drive variant of the system, and the WILL, a joint venture between Heuliez, Michelin, and Orange. The WILL looks like a conventional European front-drive five-door compact sedan but is equipped with Wi-Fi communication via the Orange telecommunications network. The WILL can also be produced as a light commercial vehicle form. Power comes from two Michelin Active Wheels fitted at the front.
Downsizing of components is said to be key to the design of the Active Wheel. The principal component is a compact electric motor rated at 30-kW continuous output. A second motor provides power for the active suspension system, fitted vertically across the diameter of the wheel. A compact concentric coil spring provides the mechanical suspension. Michelin claims that the system offers a suspension response time of 0.003 s and is able to correct pitching and rolling automatically.
Finally, a ventilated brake disc is fitted inside the rim. Because it is larger in diameter than a conventional brake disc, the disc depth is smaller, which helps to provide the compact packaging needed.
With propulsion and suspension components packaged in the wheel, it would free up space at the front of the car, which could be used to improve the absorption of impact energy. Other advantages include the possibility of a design incorporating a flat floor, better interior packaging, and reduced vehicle weight.
The Active Wheel could be powered from batteries, a fuel cell, supercapacitors, or a combination of sources. Michelin claims that energy consumption and emissions could be reduced, depending on the source of the electric power. For example, a WILL powered from renewable energy sources could produce equivalent emissions of 10 g/km in Sweden, 20 g/km in France, or 80 g/km in Germany.
Aisin of Japan also showed a prototype hub
motor at the Paris show, using a more conventional approach. The wheel
was fitted with a standard disc brake and would require more