Volvo reveals hybrid flywheel secrets

By Jack Rix

31st May 2011

Volvo is taking a new approach to hybrid technology. First tests of a flywheel system, similar to the KERS used in F1, will take place in the second half of 2011 and could pave the way for more cost-effective hybrid cars in the future.

The Swedish manufacturer claims the light, cost-efficient and efficient solution can makes a four-cylinder engine feel like a six-cylinder, thanks to a power boost effect, and at the same time reduce fuel consumption by up to 20 per cent. 

The new system, known as Flywheel KERS (Kinetic Energy Recovery System), is fitted to the rear axle. During braking, the dispersed energy causes the flywheel to spin at up to 60,000rpm. When the car starts moving off again, the flywheel's rotation is transferred to the rear wheels via a specially designed transmission.

The combustion engine that drives the front wheels is switched off as soon as the braking begins. The energy in the flywheel can be used to accelerate the vehicle when it is time to move off once again, or to power the vehicle once it reaches cruising speed - offering as much as a 80bhp boost to the engine and cutting 0-62mph times significantly.

In the past, flywheels made of steel have been too bulky and not offered enough rotaional energy, but Volvo's proposal will be made from carbon fibre, weighing just 6kg, and will rotate within a vacuum to keep friction to a minimum.