South Africa’s Ambixtra Sustainable Technologies believes that its so-called Variable Spark Ignition system can replace conventional spark plug technology. To find out how, Matthew Beecham talked with Deon Smit, CEO and James Mackenzie, vice president of development, Ambixtra Sustainable Technologies.
Could we start by talking about your Variable Spark Ignition system. What is it?
Firstly, the development has been divided into three distinct phases, each phase offering a distinct product, utilising a core electronic technology.
- Phase 1, being the VSI (Variable Spark Ignition),
- Phase 2, the API (Ambixtra Plasma Ignition), and
- Phase 3, IPP (Intelligent Plasma Plug).
Thus, to answer your question:
The VSI system is a novel ignition coil with a low inductance and secondary resistance of 65 ohms, where the energy level can be varied (1 to 1000 mJ), the spark duration can be varied (up to 6ms) and if desired, the number of sparks can be varied during a combustion cycle.
The API is a high energy (2000 mJ), electronically driven novel ignition coil and a plasma plug, which allows varying of the energy level as well as the plasma start-stop parameters (hence the duration), in a combustion cycle.
The IPP is the final phase of the development where effectively the ignition coil and the plasma plug forms an integral unit.
It must be added that VSI can appropriately be applied to engines that require a traditional coil-spark plug configuration but need the spark variability to achieve combustion benefits.
API will be appropriate for engines that require a plasma solution, similar to a traditional coil and plug configuration but with the view to migrate to the IPP phase.
Ideally the IPP can be industrialised in collaboration with whomever Ambixtra partners with for the manufacture of the full system.
Who invented it?
The core IP was jointly invented by two astrophysicists at North-West University, where Ambixtra has a development centre. Prior to moving into the astrophysics research environment they achieved degrees in electronic engineering and then went on to attain PhD’s in Astrophysics, hence the competence in electronic circuit design.
Did the ideas and technology originate from the automotive industry?
No, the IP was developed out of necessity to solve a problem in an astrophysics research project.
It originated from a solution in solving a challenge in measuring fast moving gamma particles where ultra fast electronics were required to detect or simulate a Cerenkov light shower arising from a cosmic gamma-ray.
The success of this new electronic detector unlocked fast switching electronic applications in other industries which were patented.
Out of scientist curiosity, one of the areas investigated was the application to a prototype ignition system, which showed unexpected good results and hence the ignition application was developed.
What does it do and how does it work?
At the core of this novel technology is the electronic drive circuit that enables the system to switch significantly faster than what is currently available on the market. Our system switches in the order of nano seconds.
From this technology, three patents were patented, these covering the following salient points:
- A novel high frequency driver circuit that transfers energy through a low impedance novel coil into the combustion chamber via a novel plug to create a plasma inside the combustion chamber.
- A complete charge and discharge cycle is delivered well within the requirements of high revolution engines while the amount of energy transferred per ignition cycle may be varied in two ways – duration and intensity.
Why is it useful?
It enables ultra lean combustion and hence CO2 reductions.
The ignition pattern is controllable which allows for a flexible engine management system to suit various fuels and conditions.
The system can be adapted to ignite combustion engines operating in the order of 40bar.
It operates under extreme lean mixtures and because of the fast switching, early ignition has a tremendously positive impact under cold-start conditions.
Why is it different and how is it significant?
The controllability that allows one to vary the energy intensity and duration.
Within the industry a lot of work has been done to achieve ignition variability; however the electronic circuits tend to be quite complex in comparison with Ambixtra’s technology.
The Ambixtra system also enables effective operation under very high pressure conditions which is one of the challenges in the ignition coil/ engine environment.
In the case of API, the plasma volume can be up to 100 times larger than a traditional spark generated from a spark plug in the combustion chamber, thus ensuring almost complete combustion in either stratified or homogenous combustion regimes.
What does it replace?
Conventional spark plug technology.
What does it threaten?
Certainly spark plugs as we know it will be quite different. Hence we are talking to manufacturers who will be willing to co-operate with us on industrialisation and subsequent manufacturing of the system
Could you tell us a little more about your plasma plug?
The API is based on the same novel technology used in the VSI, but operates at a higher frequency, but with even less secondary resistance of approximately 12 ohms. The electronic driving circuit is also less complicated and that makes the complete ignition system quite cost effective. The plasma plug design is very similar to a standard sparkplug with slight internal and external modifications.
There is 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?
Studies conducted clearly indicate that the need for increased energy is driven by the industry developments towards down sized, turbocharged and GDI engines to reduce emissions and improve fuel consumption.
To be able to improve combustion effectiveness at leaner fuel ratios at higher pressures not only do you need higher energy but also the ability to control the ignition at the right time and for the right duration.
As distributorless or direct ignition systems enter the replacement cycle, is there likely to be greater demand for coils and engine control units?
Yes, there will be aftermarket growth in this segment and this growth would be aligned with the age of vehicle parc’s in the various countries.
In terms of tomorrow’s ignition system designs, what could we expect?
Ignition systems have in the past, been treated as a hang-on part with little new innovative developments to improve the systems.
With the increased drive on legislated emission reduction a new focus has been put on the ignition system as a complimentary tool to achieve the emission goals.
In the near future you will see new and innovative systems that produce an effective ignition medium to ensure efficient and improved combustion to reduce emissions and fuel consumption.
Are there any other trends you are seeing in the evolution of ignition systems?
Well certainly coils and spark plugs as we know it today will disappear completely. We could expect to see self sensing ignition systems that adapt according to different driving conditions.