Ionic Current Combustion Analysis: a quick overview
This project involves the development of a universal, ionic-current knock detection system, for use in a wide range of engine types and applications. Unlike traditional acoustic methods, the ionic-current signal is minimally impacted by irrelevant and unmonitored factors such as external vibration, engine noise, and environmental conditions, enabling a substantially more universal detection algorithm to be developed. The system is not only very simple, minimally intrusive to the operation of existing vehicle systems, and cost effective – but it is also predicted to outperform even advanced instrumentation methods in small displacement, high speed engines. I would love to cover this topic in detail some day, but in the projects current state (and with a publication planned for the future), I am fairly limited on what I want to say until the remaining data is collected and time has been spent finding the practical limits of this implementation. Once done, I can assure you that this quick overview will become a piece of comprehensive documentation.
The principal of operation involves using an engines spark plug to measure the engines cylinder pressure trends during critical combustion phases. By applying a voltage of ~100V across the spark plug immediately following the initiation of a combustion event, and monitoring the resultant current flow, it is not only possible to monitor the presence of knock, but also the point in the engines cycle where the cylinder pressure reaches a maximum – a critical parameter for optimizing the performance of an engine in real-time, cylinder by cylinder.
The general principle of this technology is not new – development began as early as the mid 90s – but the refinement of this technology to develop a universally beneficial combustion analysis module for use across a wide range of engine types is. Preliminary testing was highly encouraging and impactful. As a result, this project has grown from a personal project into a long term research effort, with a paper in the pipeline – and hopes of it being published within a year. An early development of this system enabled a doubling of performance and efficiency of this seasons FormulaSAE powertrain – ultimately helping drive us to a successful, top 10 finish and an award from Cummins for innovation with substantial impact on sustainability.
Once further data is collected, and a paper published, I will be able to elaborate further regarding how the development and integration of this technology was carried out, and how I’ve managed to use it to improve the performance and efficiency of my personal vehicle and the FormulaSAE vehicle - and how it can very likely be implemented on other vehicles with ease.
