Smart Spark Plug for Proper Combustion Timing in Gasoline Engines and Detection of Misfire and Knock

Internal combustion engines are required to achieve production goals of better fuel economy, improved fuel economy and reduced emissions in order to meet the current and future stringent standards. To achieve these goals, it is essential to control the combustion process using an in-cylinder combustion sensor and a system that produces a feedback signal to the ECU. This paper presents a system based on combustion ionization that includes a newly developed smart spark plug capable of sensing the whole combustion process. A unique feature of the smart spark plug system is its ability to sense the early stages of combustion and produce a complete ion current signal that accurately identifies and can be used for the control of the start of combustion. This is not the case for the conventional spark plug where the start of combustion cannot be determined from the ion current signal because its early part is distorted or completely overshadowed by the strong electromagnetic field produced by the spark ignition system. In addition to its ability to detect and control the start of combustion, the new system can detect other combustion related problems such as misfire and knock. The paper describes the construction of the smart spark plug and compares its ion current signal with that produced by the conventional spark plug. The new system, developed and patented by IC LLC, can be applied in current production spark ignition engines as well as for the development of future advanced concepts engines.