Effect of design and operating parameters on the ion current in a single-cylinder diesel engine

Abstract

Ion current has been the subject of extensive research in gasoline engines forin-cylinder combustion sensing and as a feedback signal for closed-loop engine control. The sources of the ion current in gasoline engines have been identified. Such identification is not the case in diesel engines. This paper presents experimental data and analysis of the ion current produced in a single-cylinder diesel engine equipped with an electronically controlled common-rail-injection system using an accessible engine control unit. The experiments cover a wide range of engine speeds, loads, injection pressures, and injection timings. The effect of each operating parameter on the shape of the ion current signal, as well as its amplitude, timing, and phase shift relative to the rate of heat release, are determined.