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Volvo brings toy idea to life

2013-04-26 10:52

CARS AREN'T TOYS? Volvo has completed testing of flywheel technology and Derek Crabb (inset), vice-president for powertrain engineering at Volvo, claims the results are financially viable. Image: Newspress

Volvo has completed testing of kinetic flywheel technology - and the results confirm it is a light, financially viable and eco-efficient solution.


Remember those small toy cars you used to play with? You had to either pull them back and let go (pull-back motor) or push forward to get the engine going (friction motor). The friction motor toy used flywheel technology to propel it; a similar idea has been tested by Volvo.

Watch a video demonstration

The system, known formally as Flywheel Kinetic Energy Recovery System, is fitted to the rear axle. The energy produced from braking causes the flywheel to spin at up to 60 000rpm. When the car starts moving again the flywheel's rotation powers the rear wheels.

The engine that powers the front wheels is switched off as soon as braking begins. The energy created by the flywheel can then be used to accelerate the vehicle when it starts moving again or to power the vehicle once it reaches cruising speed.

Derek Crabb, vice-president powertrain engineering at volvo, said: "The testing of this experimental system for kinetic energy recovery was carried out during 2012. The results show that this technology combined with a four-cylinder turbo engine has the potential to reduce fuel consumption by up to 25% compared with a six-cylinder turbo engine at a comparable performance level.

It makes a car with a four-cylinder engine accelerate like one with a six-cylinder unit, giving the driver an extra 59kW. The flywheel's stored energy is sufficient to power the car for short periods. This has a major impact on fuel consumption.”


Since the flywheel is activated by braking, the length of time it spins is limited; therefore the technology is most effective while driving with repeated stops and starts.

Flywheel propulsion assistance was tested in a Volvo 260 in the 1980s and steel flywheels have been evaluated by various manufacturers. However, since steel is heavy and has limited rotational capacity the flywheel Volvo used is made of carbon fibre, weighs about six kilograms and has a diameter of 20cm. The carbon-fibre wheel spins in a vacuum to minimise frictional loss.

Crabb concluded: "The next step will be to evaluate how the technology can be used in upcoming car models.”

Read more on:    volvo

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