Michelin In-Hub Electric Drive

Hub or wheel motors have been used in prototype electric cars and trucks, though none are yet in volume production. They are quite common in electrically assisted bicycles and other personal transportation vehicles. Now, Michelin has taken the hub motor idea one step further with its Active Wheel. Besides the electric drive motor found in all hub motors, the Active Motor also includes the vehicle’s suspension and brake components.

Along with a small but powerful main drive motor, a second motor powers the active suspension system that’s fitted vertically across the diameter of the wheel. The suspension, which is now electrically controlled, can automatically and very rapidly correct for pitching and rolling. Response times of just 3/1000ths of a second are claimed. Finally, a ventilated brake disc is fitted inside the rim. Because it’s larger in diameter than a conventional brake disc, the disc depth is smaller, allowing more compact packaging.

According to Michelin, the Active Wheel greatly simplifies vehicle design because an engine gearbox, clutch, transmission shaft, differential, and shock absorbers are no longer needed. Besides being simpler, the vehicle can be substantially lighter and thus more energy efficient. Packaging propulsion and suspension components in the wheel frees up space at the front of the car, which could be used to improve the absorption of impact energy. Other advantages include the potential for a flat floor and more efficient interior packaging.

The Active Wheel is very versatile and is easily adapted to both battery electric and fuel cell vehicles. Two Active Motors, either in front or rear, can be used for two-wheel drive; four can be installed for four-wheel or all-wheel drive. As an example, the Active Wheel system was used in two concept cars also unveiled at the same show. The Venturi Volage, a futuristic looking two-passenger coupe, featured four Active Wheels to provide four-wheel-drive. The WILL, a rather conventional looking European-style front-drive five-door compact sedan, is equipped with two Active Wheels in front.

For the performance-oriented Volage, four liquid-cooled, 50 kilowatt motors were used to provide a total of 268 horsepower and a top speed of 93 mph. Quick acceleration with a 0-60 mph ETA of under 5 seconds is claimed. The sleek Volage has a carbon fiber body that’s essentially wrapped around the battery system. A driver can customize the Volage for speed, economy, or comfort using a dashboard touch screen. For example, the driver can give preference to range rather than power, or comfort rather than speed. The active electric shock absorber system allows total adaptation to the type of road surface and driving style. The Volage could go into limited production as early as 2012 with each one hand built at about a half million dollar a copy.

The WILL is the product of a joint venture between Michelin, French coachbuilder Heuliez, and France Telecom’s Orange brand. The lightweight vehicle has two trunks. Since there is no engine beneath the hood, the front end is designed to absorb impact in case of a collision. The active suspension in the two front wheels can quickly sense any pitch or roll and instantly adjust to offer what’s claimed to be unprecedented levels of comfort and road holding. The WILL can also be produced as a light commercial vehicle.

The first WILLs are planned for 2010 for professional drivers, fleets, and municipalities in Europe, with the general public likely waiting an extra year. It could be available with three different lithium-ion battery sizes for ranges of 150, 300, or 400 kilometers (93, 186, or 249 miles) with prices ranging from about $27,500 to $34,000. A fuel cell powered WILL is also a possibility with a light commercial version in the lineup as well..