Motoring Weekly

The Podcast for the Australian Historic Road & Racing Community

You are here: Home / Technology / Engine Technology / Flywheels

Flywheels

by Leave a Comment

One topic that I discussed on my earlier blog was the concept of using the flywheel of an engine to be more efficient. Well, as you would imagine, things have moved on quite a bit in the past 3 or 4 years. When I first wrote about this topic, KERS was not yet in Formula 1 and the technology had just had another breakthrough in design and efficiency.
Firstly let’s revisit the concept of a flywheel. Like many technologies today, the flywheel evolved through the ages and can be seen over 4,000 years ago. the first flywheels were actually spindles used in weaving and the creation of threads and pottery was made using a wheel that kept spinning long after the potter had put any effort in to it. Little did they know that the wheel stored kinetic energy and had transferred that energy from a small wheel that was being turned by the worker. When the Industrial Age was ramping up, James Watt used one with a steam engine to provide a similar function – he needed the engine to continue producing energy and needed a mechanism to smooth out that energy to the machines that were being driven by it. It is this concept that has now morphed from the weaving and pottery industries to being a major component of the internal combustion engine.So the flywheel does two important functions:
1. It balances the engine, making the actual motor more efficient and
2. It takes the energy from the motor and temporarily stores it until it is used by the propulsion system, ie through the gearbox.

Function 1 is still important. If the engine is not smooth, you will destroy everything around it and even the motor itself. Clearly in a car this is not acceptable and as the speeds increase (not just road speed, but engine revs) this becomes even more important.

1244232271-Fidanza-Flywheel
This is a classic flywheel from an engine – a Fidanza model. Image from tunersports.com.
Let’s concentrate on function 2. The last time I wrote about this subject, the technology had recently evolved in size and weight to make it viable for uses other than with a combustion engine. Engineers had figured out this important factor – making the flywheel more portable and therefore more useable. We have seen this in KERS on F1 cars and I’ll go into detail on this technology in a later post. Basically the concept is to capture “lost” energy in a flywheel and deliver it back as power a short time later to aid performance.Now let’s take a step into physics to explain the concept further and start with the meaning of kinetic energy. This is the energy that an object has when it is in motion – for a flywheel this would be called rotational inertia as it is spinning on an axis. In physics, the term “work” is used to describe the effort desired to get the object moving to its desired velocity. In an engine this effort comes from the pistons. The kinetic energy remains until more effort is applied to slow down the object. This could be from using the stored energy to provide effort to another device.Think about riding a push bike – you are converting energy from food to power to the wheels via your legs to speed up. As you go faster your balance is better due to the rotational inertia from the wheels. It all fits nicely together.

You see flywheels on most machines – especially agricultural ones as they help to deliver the power to another labour saving machine. Often old mills and factories had huge flywheels in them and today they are seen as things of great beauty.

1894450696
This is an example from newsandstar.co.uk and used at Carrs Flour Mill in the UK.

But what about today? Ricardo, a British engineering firm had just released their second generation kinetic storage system when I last wrote on the topic. They had developed a hermetically sealed carbon fibre flywheel system that was light and compact that took the technology a step further, so much so, they had applied for 9 patents! The developments partly funded by the UK Government were with Allison Transmissions and other partners to improve the efficiency of buses.

Torotrak, one of the partners with Ricardo and Allison has recently bought Flybrid Automotive to further develop the systems used in race cars. The Flybrid system, also made of carbon fibre, spins at 60,000 rpm to store “lost”energy.

_wsb_496x530_Flywheel+Cutaway+Annotated1

This is the Flybrid system – a mechanical battery! Image from flywheelcapacitor.com.

Earlier this year, Ricardo announced the TorqStor, an evolution designed for construction equipment that saves fuel by reusing energy that would have been wasted otherwise.

So this technology is now leaping ahead and getting smaller and more reliable. Soon household uses will start to appear as developers realise that any flow of air or water could turn a device that converts the energy into a “mechanical” battery. So we literally go full circle back to water wheels and windmills that did this centuries ago! And that is why the world still turns after billions of years…..

Leave Motoring Weekly a comment! Your views are very welcome.

This site uses Akismet to reduce spam. Learn how your comment data is processed.