Two new wheel bearing hub assembly systems were introduced at the Paris Motor Show, incorporating electric motos and other suspension components.

Michelin introduced a commercial version of its Active Wheel assembly [Active Wheel press kit {PDF format}], combining the hub ansd bearing assembly, active suspension module, compact coil spring, brake caliper, brake rotor, and electric drive motor.

The units can be deployed at the front or rear, or on all four wheels at once. The unit's electric motor is rated at 30 kw, with a second motor powering the active suspension module. With just 3ms response rate, the active suspension system is among world's most responsive. Active Wheel modules were on display incorporated in the Venturi Volage, expected to be available from the Monaco-based electric auto manufacturer by 2012.

While the Michelin units have been under development for more than a decade, actual rollout to a commercially viable volume application is still several years away. These are expected to represent the ultimate electric motor drive solution, as there is no need for the vehicle to package an engine or drivetrain -- just the passenger compartment and fuel cell or battery pack.

Aisin, a major transmission and drivetrain supplier to automotive OEMs worldwide, also introduced a similarly developed wheel hub and bearing unit with integral electric drive motor [3-page white paper excerpt {PDF format}]. The Aisin corner unit is simpler, without the Active Wheel's complex integrate active suspension components. Unique to the Aisin unit is an integrated oil cooling system, necessary for the hub units to avoid overheating the motors and dropping efficiency and performance.

Aisin's in-wheel drive units are also several years away from commercial applications, but its dual-motor hybrid drive system is currently in the Ford Escape and limited-production Toyota electric vehicles.

Back in 2005, NTN showed in-wheel electric motor driven hub units at the Tokyo Motor Show, prototyped in a Mitsubishi Lancer Evo MIEV. The MIEV is unique in that the electric motor stators are inside the wheel but in a ring outside the brake disk and caliper.