December 3, 2008 Known to our readers for transport innovations like the Tweel airless tire, Michelin has announced that it will partner to bring an affordable electric car powered by its Active Wheel System to the roads in 2010. Featuring two electric motors housed within the wheel, one for traction and braking and the other for electric active suspension control, the system has revolutionary potential - no more engine under the hood, no more traditional suspension system, and no more gearbox or transmission as all the essential components have been integrated into the wheel itself.
The Future of Car Design
First showcased at the Bibendum Challenge in 2004 in a fuel cell powered electric concept vehicle called Hy-Light, the Active Wheel System could outperform Ferrari and Porsche in a straight line when it comes to braking. While a typical high performance supercar takes about six seconds to come to a complete halt from 100km/h, the Michelin concept does it in a mere 2.8 seconds at up to 1G.
Michelin have been developing the Active Wheel system for over 12 years in conjunction with Swiss based Paul Scherrer Institute (PSI) and has now unveiled the Opel Agila based Heuliez WILL - the first production electric car with Active Wheel drive system. The WILL results from a partnership between Michelin and coachbuilder Heuliez and although it may represent the next generation in transportation technology, its designers and builders want to convey a comfortable familiarity with the empty storage space in both the front and rear trunks being the first hints that something unusual is afoot.
Wheel Motor technology should trigger a paradigm change in car design. Without engines, transmissions and ancillary systems, smaller cars can carry more people and cargo. Impact absorbing collapse zones in both front and rear offer potential safety improvements and advanced active safety features such as anti-lock brakes and stability control can be taken to new levels with direct computer control of each wheel motor. For example, electric active suspension can react in 0.0003/sec and control ride height, pitch under braking and roll during cornering replacing passive anti-roll bars.
Technical Specs
Each Michelin in-wheel motor weighs 42 kilogram (95 pound) and includes a 30 Kilowatt water-cooled drive motor of a similar size to a conventional starter motor. The motor has a spur gear that drives a rind gear on the hub. A second electric motor operates the active suspension via a gear rack and pinion that effectively replaces the normal hydraulic shock absorber (no news on if they are used as regenerative shocks). There is also a coil spring to hold the static load of the car and a small outer rotor disc brake. The wheel motor is attached to the vehicle chassis by a single lower control arm suspension arrangement.
With the smallest of the battery packs on board, the prototype Heuliez WILL weighs in at 900 kg, 75 kg less than the internal combustion engine powered Opel Agila.
While the earlier Hy-Light prototype had four wheel motors and could be switched between two wheel drive and four wheel drive the Heuliez WILL comes with only two wheel drive. Together, the two front wheel motors deliver a combined 60 Kw (81 horsepower), which can peak up to 120 Kw (163 hp) for short sprints. The car should do 0-100 km (0 - 62 mph) in 10 seconds and will have a max speed of 140 km/h (87 mph).
Three versions will be available in 2010 with three different sizes of Lithium-Ion battery module configurations, offering ranges of 150, 300 and 400 km (93, 186 and 248 miles). Drivers will have the option of changing from one module size to another in the same vehicle depending on their needs. Just like hybrids, the Active Wheels recover energy during braking to extend vehicle range. The in-wheel motors are reported to be 90% efficient, compared to about 15% efficiency for a conventional vehicle in city driving.
Test versions of the WILL are on the road now with production scheduled to start in 2010 with a first year output target of several thousand vehicles. The target price of 20 to 25,000 euros (USD$27 – 34,000) puts the Will in the affordable electric vehicle class, along with the much anticipated Chevy Volt. If you are willing to wait a bit longer, and spend a bit more, look for Active Wheels on the Venturi Volage in 2012.
Paul Evans
Michelin Active Wheel system demonstration:
