Continuing its series of interviews with leading automotive powertrain suppliers, Matthew Beecham talked with Gian Maria Olivetti, vice president for Technology and Innovation, Powertrain Division, Federal-Mogul about its Advanced Corona Ignition System. ACIS is a new technology that replaces the spark plug with a device that generates an electrical field, can improve cars’ fuel economy and CO2 emissions by 10 percent.
Let’s start by talking about your Advanced Corona Ignition System. What is it?
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Advanced Corona Ignition System (ACIS) is a new and somewhat different way of igniting the fuel in gasoline engines. Compared to conventional spark ignition systems, corona ignition uses high-intensity cold plasma to create a significantly larger ignition source, spread throughout the combustion chamber. The technology produces multiple streams of ions to ignite the fuel mixture by using a high energy, high frequency electrical field. This provides more widespread ignition than a spark ignition system, making it suitable for a wide variety of combustion strategies and air/fuel mixture characteristics.
Why is ACIS useful?
ACIS technology’s superior ignition performance creates more thorough combustion within the chamber. This allows engine designers to use more advanced combustion strategies that improve fuel economy and emissions, while still providing the kind of driveability that drivers expect. ACIS makes strategies such as lean burn, highly diluted fuel-air mixtures and very high levels of exhaust gas recirculation (EGR) simpler and more effective.
Using ACIS to recalibrate the combustion strategy can produce some very attractive improvements in fuel efficiency. We have already recorded fuel consumption reductions of around 10 percent on a 1.6-litre turbocharged gasoline direct injection engine. We’re just getting started still though: there is potential for further improvements.
Why is it different and how is it significant?
Conventional spark plugs create only a very small electrical arc in the gap between its electrodes – it’s just a couple of millimetres. ACIS produces repeatable, controlled ionisation throughout a wide portion of the combustion chamber. Eliminating the spark plug and its arc also eliminates the source of electrode erosion—the main point that affects durability in a conventional spark-ignition system, even with the use of high-end Iridium material electrodes. This prolongs ignition system durability and extends service intervals.
We can see that ACIS could play a significant role in the industry’s work to improve the environmental cost of personal mobility. The world’s vehicle parc is continuing to grow strongly. Making this sustainable will require technical solutions that range from full electric vehicles to more efficient spark ignition engines. ACIS technology will help manufacturers to develop powertrains that are more efficient and more profitable.
What does ACIS replace?
The impact on engine design and assembly is minimal. The two-piece ACIS igniter architecture directly replaces a traditional coil and plug system. From the outset Federal-Mogul set out to create a technology that could package within the space currently occupied by the spark ignition system, ACIS will be easy to implement in high volume applications for both current and future powertrain architectures.
What does the technology threaten?
ACIS certainly challenges the notion that the internal combustion engine has is close to the limits of its development potential. Federal-Mogul is continuing to develop new spark plug technologies that we will offer vehicle manufacturers. The global vehicle parc is predicted to reach more than 1.2 billion cars by 2015 – there will be a strong market for spark ignition systems for some time to come. We expect ACIS to complement conventional spark ignition systems in future.
When will ACIS be ready?
The timing of the technology’s introduction is really a question for our customers. ACIS is currently undergoing development with several customers and could be ready for production within three years. Start of production depends on the customer timetables for introducing their new engine evolutions.
ACIS uses materials that are already proven and used in automotive applications and, because it packages so simply, it will be straightforward to introduce in volume once development is complete and the decision made.
Could ACIS be used for non-automotive applications?
Certainly. A number of non-automotive applications could benefit from ACIS technology. Large stationary engines and generators use a variety of fuels that require an ignition source capable of providing the best possible fuel economy with the lowest emissions. There is also growing use of natural gas as a fuel for commercial vehicles and these require ignition systems. Corona ignition could be beneficial in all these applications.
Are you also seeing more use of electronics in the ignition coil itself? How does that trend in Europe compare to the situation in Japan?
Electronic content is continuing to increase. The majority of spark plugs are now electronically controlled and more and more applications require electronic content embedded in the coil to support the control of the increasingly complex ignition strategy and to enable diagnostic features. The situation in Japan is broadly similar.
As far as the ignition parts aftermarket is concerned, what notable changes are occurring say with regard to ECUs, coils, caps/rotors and distributors, and/or wire sets?
The aftermarket is continuing to track the trends in the original equipment markets and so the wire set aftermarket is no longer growing. Most engines now have one coil per cylinders to provide optimum control and to allow the engine management system to deactivate individual cylinders in the event of a problem. The main change is that drivers and workshops understand the importance of fitting OE-quality replacement parts to modern powertrains.
As distributorless or direct ignition systems enter the replacement cycle, is there likely to be greater demand for coils?
The demands placed on coils are increasing but, as a partner to vehicle manufacturers for the development of original equipment, Federal-Mogul was involved in developing higher specification ignition systems. Knowing how much resource we put into the development, testing and validation of our direct ignition systems’ design, we don’t expect an increase in failure that would result in increased demand for replacement coils.
Ignition systems these days have longer service lives. As engine downsizing trends continue and engines’ specific power outputs increase the importance of fitting OE-quality replacement parts will become more important. The spark plugs that we supply as original equipment to these engines have far greater mechanical strength and more advanced and robust dielectrics to ensure they perform correctly under the additional stresses. The new materials used mean that the market remains healthy with high unit values.
There is also a clear trend toward increasing energy requirements. To what extent is that trend for more energy requirements being driven by more direct injection gasoline applications and emissions regulations?
There is a direct relationship between the spark energy requirement and the in-cylinder pressure, prior to ignition. More aggressive combustion strategies for fuel economy improvement are enabled by direct injection, and increasing the compression ratio is also beneficial for fuel economy. This is leading to air-to-fuel mixtures and in-cylinder pressures that are more challenging to ignite and which are requiring continually greater spark energy. This trend will continue pushing conventional systems close to their limits.
Are there any other trends you are seeing in the evolution of ignition systems?
Spark plug specifications are becoming more diverse and service intervals have been extended so people change their plugs less frequently. Federal-Mogul provides a number of solutions that cover the full range of customers’ financial and technical requirements. Champion Iridium spark plugs have the highest specification and are suitable for LPG or E85 alternative fuels. Other premium plugs include the Platinum range, while cost effective products like the Copper Plus range support the needs of even the most cost-conscious motorist.
