Tweel - Non-Pneumatic Technology from Michelin

Tweel - Non-Pneumatic Technology from Michelin

At the recent North American International Auto Show ( NAIAS) Michelin showcased one of their latest innovations, an integrated tyre and wheel combination that does not use air, making it impossible to go flat.

The new product, which is being marketed by Michelin under the brand name "Tweel" is being used in a variety of specialist applications. For example, the Tweel has been made available as an enhancement for future iBOT mobility systems.

Invented by Dean Kamen, the iBOT device has the ability to climb stairs and navigate uneven terrain, offering mobility freedom impossible with traditional wheelchairs. Additionally, Segway LLC's Concept Centaur, a prototype self-balancing technology to a four-wheel device, has also been equipped with Tweel to increase its performance potential. Beyond these first real-world applications, Michelin has additional projects for Tweel on construction skidsteers and a variety of military vehicles.

" Major revolutions in mobility may come along only once in hundred years, "said Terry Gettys, president of Michelin Americas Research and Development Centre in Greenville, S.C. " But, a new century has dawned and Tweel has proven its potential to transform mobility. Tweel enables us to reach levels of performance that quite simply aren't possible with today's convention pneumatic technology."

The most intriguing application may be Michelin's early prototype fitment for passenger cars and with this in mind the company has released a video of promising wheel performance on an Audi A4. " The Tweel's automotive application, as demonstrated on the Audi, is definitely a concept with strong future potential,"said Gettys. " Our focus is on entering the market with lower speed, lower -weight Tweel applications. What we learn from our early successes will be applied to Tweel fitments for passenger cars and beyond."

The heart of Tweel innovation is its deceptively simple looking hub and spoke design that replaces the need for air pressure while delivering performance previously only available from pneumatic tyres. The flexible spokes are fused with a flexible wheel that deforms to absorb shocks and rebounds with ease. Without the air needed by convention tyres, Tweel still delivers pneumatic performance in weight-carrying capacity, ride comfort and the ability of being impervious to nails on the road.

Tweel performance can be tuned independently of each other, which is a significant change from conventional tyres. This means that vertical stiffness ( which primarily affects ride comfort ) and lateral stiffness ( which affects handling and cornering) can both be optimized, enabling new performance levels not possible for with normal pneumatic tyres.

The Tweel prototype, demonstrated on the Audi 4, is within 5% of the rolling resistance and mass levels of current pneumatic tyres. That translates to within 1% of the fuel economy of the OE fitment. Additionally, Michelin has increased the lateral stiffness by factor of five, making the prototype unusually responsive in its handling. The tread will last two to three times as long as today's radial tyres, Michelin say, and when it does wear thin, it can be retreaded.

Two other new technologies were introduced by Michelin in Detroit. Michelin Airless is a different non-pneumatic technology, which enables vehicles to run safely and comfortably because its elastic characteristics are controlled longitudinally, transversally and vertically. A car doesn't have to stop even if one or more of the radial bands break or are damaged. The Michelin Airless is being tested on passenger cars and motorcycles, but could be fitted to other vehicles as well.

Meanwhile, Michelin Active Wheel is an integrated module comprised of a conventional tyre, plus an active electric suspension, a disc brake and an electric motor to provide traction and much of the braking power. Its compact size offers automotive engineers considerable design flexibility.