A British materials company is planning further growth of applications for its ‘activated carbon’ air suspension technology following its use on current-generation Audi A6 and A7 models. Activated carbon is formed from organic carbon matter, typically made up of stock like coconut shells or sawdust. To learn more, Matthew Beecham spoke to John Coakley, Carbon Air CTO.
Could you tell us a little about Carbon Air, how the company came about and who funds you?
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Carbon Air was founded in 2011. I was the Technology Transfer Officer at the University of Salford, where a PhD researcher was investigating the benefits of activated carbon for loudspeakers. I realised that activated carbon might be of great benefit in vehicle air springs. We are funded by venture capital, the University of Salford and private investors.
Could you cast your mind back to how you came up with the idea for your activated carbon air suspension technology and was there a Eureka moment?
It was 2010: the PhD researcher was appraising claims that activated carbon improved the bass response of a loudspeaker by changing the behaviour of air through a process called adsorption. I didn’t really understand it and was discussing with a professor in the acoustics research department how a loudspeaker worked; specifically, why did activated carbon improve the quality of the sound produced. I asked whether the same principle would work in air springs and of course the professor had no clue and little interest in possible automotive applications. But the idea was born and I filed a patent in 2010 covering a range of applications for activated carbon, including to automotive air springs.
It sounds like you are bending the laws of physics. How does your technology work?
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By GlobalDataActivated carbon in various guises has been in use for hundreds of years. The material changes – in a predictable and specifically tuned way – the behaviour of air in the air spring chamber under varying degrees of pressure. By the process of adsorption, activated carbon enables air molecules to pack more closely together, thereby increasing the apparent volumetric capacity of a container.
When activated carbon is added to a container and the air inside is pressurised, it ‘adsorbs’ air, allowing it to ‘hold’ up to six times more air than an identical container without activated carbon. Therefore, instead of pressure building steeply, resulting in the air becoming much ‘stiffer’ at higher pressures, the pressure builds more gradually, delivering a more linear response pressure curve with a greatly reduced ‘stiffening’ of the pressurised air.
Can you tell us a little more about the use of coconut shells and other organic content?
Activated carbon is formed from organic carbon matter, typically made up of stock like coconut shells or sawdust, which is crushed and carbonised in a deficiency of air at temperatures of around 400 C. The resulting char is then ‘activated’ with steam at temperatures up to about 1000 degrees Celsius, using energy largely from the material itself. No other chemicals are used in the process and the combustion of the waste gases are employed in raising the temperature for the activation stage. This process creates within the carbon a dense network of microscopic pores.
Who are your customers and on which cars can we find it fitted?
Carbon Air has licenced its technology to one of the world’s largest air spring manufacturers, which is now supplying Carbon Air-enhanced air suspension to Audi for its current-generation A6 and A7 models. We are talking with a number of vehicle manufacturers and tier one air suspension suppliers about the next installations.
The need for air suspension – and the benefits it brings in terms of self-levelling and ride height adjustment – is increasing as the industry transitions to electric vehicles.
An interesting consideration is that the need for air suspension – and the benefits it brings in terms of self-levelling and ride height adjustment – is increasing as the industry transitions to electric vehicles. For stability and packaging, it is crucial for EV batteries to be positioned as low as possible; and it is important for cars to ride as low as possible for aerodynamic efficiency at speed. But at the same time, those vehicles and their low-slung batteries must be protected on broken roads and in urban environments with speed humps and kerbs. So they need to ride higher sometimes, low at others: this is where air springs offer a proven solution.
Looking further ahead, developers of autonomous vehicles have identified that nausea can affect passengers that are working, reading or watching screens while the vehicle is underway: this may be partly attributed to the way vehicles ride and take corners. Air suspension systems here can also help, by adjusting dynamic characteristics in real time, depending on the speed, the mass of the passengers and load being carried and the road conditions.
In these air suspension applications, among a host of others, Carbon Air’s activated carbon offers significant advantages: a more tuneable and more linear response, as well as helping to reduce the packaging requirement of air suspension systems. And when the design engineer is required to tailor the performance of an existing spring to match a new requirement late in the day – for example, when a heavy battery pack or an extra row of seats is added – then the addition of activated carbon can save the day, allowing one spring to operate across a range of loading conditions.
Furthermore, there are several opportunities beyond air suspension where we have made significant advances in our development work. There is huge potential for activated carbon to be applied to the air suspension systems in truck, train, bus and agricultural vehicle seats and Carbon Air is working with major cab seat manufacturers to develop a solution which offers comfort and stability for drivers.
Are you in partnering with other universities or organisations?
We still have close ties with the University of Salford’s acoustic research group who help us with expertise and testing, but another important relationship is with the University of Sheffield who are helping us develop an entirely new microporous material, primarily for small scale audio applications but potentially for use in everything we do. It is very lightweight, electrically insulating and features no activated carbon at all.
Are there any other mobility applications besides automotive?
We are at various stages of exploratory trials with tier one suspension suppliers and manufacturers of motorcycles, mountain bikes and snowmobiles. For keen mountain bike and motorcycle riders, the application of Carbon Air’s activated carbon technology allows an unprecedented level of tunability for damper settings, and the capability to adjust sag and shock stiffness independently of each other. For these applications, the effect of activated carbon not only decreases the stiffness of air suspension and improves linearity but also helps achieve better grip, greater impact absorption, and a reduction in vibrations transmitted to the handlebars.
Carbon Air has developed varieties of activated carbon that have a fast response, high stiffness reduction and low temperature sensitivity making it easily applicable and customisable for different types of transport in varying conditions and temperatures.
After extensive work with manufacturers and suppliers, we’re ready to bring our technology to market for wider mobility applications.
What is the potential for non-automotive applications?
In agricultural and commercial vehicles, central tyre inflation systems often used by tractors to inflate and deflate tyres when moving from fields to roads can be improved by heating and cooling activated carbon to control and adjust pressure within the tyre. Carbon Air currently holds a joint patent with Michelin for this technology and work is in the early stages.
In acoustics, car cabin insulation impregnated with activated carbon could be over 60% more compact, and our research shows that we can also eliminate tyre cavity resonance.
Similarly, loudspeakers with activated carbon inside can behave as if they are larger. The adsorption and desorption of air molecules on the surface of the carbon caused by refractions of sound waves can lower the resonant frequency and increase the richness of the sound output.
The same principals could be applied to a wide range of industrial, commercial and domestic machines and devices where it would be a significant advantage to reduce unwanted noise and early development work on this is underway.
Where does Carbon Air go from here?
After our success with the Audi A6/A7 platform we’re now looking to leverage that success with other partnerships and broader applications.
We are talking with numerous suspension suppliers and OEMs for passenger car and commercial vehicle applications. Our technology is also on trial with motorcycle and mountain bike manufacturers who are looking into applications in air springs, gas dampers, forks and shock absorbers. We are also working on solutions for air-sprung seats in buses, trucks and trains to reduce driver stress and fatigue. And, our team is at advanced stages of testing the acoustic properties of activated carbon, with applications to automotive noise insulation materials under development.
In short, we anticipate significant growth in the commercialisation of our technology and we are well positioned to work with clients across automotive and beyond to harness the opportunities of activated carbon.
