Flywheels

If you ever work in wood processing mill you’d be familiar with band-saws. The saws are attached to two big flywheels driven by AC motors. The wheels don’t need high initial torque to start rotating but once spinning, the band saw is capable of tearing apart even the biggest and hardest log.

Image: chinasawmills.com

Or, if you own a small diesel generator set – typically 5kVA to 10kVA – you’d be familiar with the tiring starting method. You need to spin a small but heavy flywheel to get the diesel engine going.

These are example of age old applications of flywheel. Let’s look at how flywheel is still relevant in today’s advance engineering. The following is an article I read from Daily Express:

What is a Flywheel?

A flywheel is a wheel that’s spun at high speed and used to store energy. They’ve been used for years in everything from traction engines to toy cars. But now Jaguar and Volvo want to see if they can be used to drive up fuel efficiency.

How would that work?

The car’s wheels would spin the flywheel, which would continue to spin until the stored energy was needed to drive the car. The stored energy would then be transferred back to the wheels via a transmission.

Are they currently used in cars?

Flywheels are an alternative to the Kinetic Energy Recovery System (KERS) most Formula 1 teams have been using last year. But although they’re permitted by the sport, no team currently uses them and neither are they found in road cars. F1 designers have worked on improving the technology but developing a flywheel is a headache; a great deal of stored energy can be lost to friction.

So what has changed?

F1 engineers have reduced the weight of flywheels using composite materials and cut friction by sealing the wheels inside a vacuum chamber. But it’s hard to make the seals between flywheel and transmission perfect. In F1, the seals only need to last for a short period of time. In road cars they need to be far more durable.

Is there a solution?

Engineering firm Ricardo has built a magnet-based system in which there’s no direct contact between flywheel and transmission. Jaguar is working with Ricardo and others on a flywheel, and Volvo is also looking into the technology for use in its vehicles.

Hope this will work towards energy efficient vehicles in the near future.

Source: Daily Express, Sunday Feb. 26, 2012