Preliminary investigation of the in-cylinder pressure signal using Teager energy operator

Abstract

The Teager energy operator (TEO) has been used in various areas, including speech analysis, image processing, machinery fault diagnostics and biomedical engineering. The operator provides a simple and efficient solution to the problem of estimating the instantaneous frequency and envelope of amplitude and frequency-modulated (AM-FM) signals. Furthermore, this method is easy to implement and has a low computational complexity. In the paper, the author proposes using TEO in an automotive application to perform preliminary investigations of the in-cylinder pressure signal. Research in this area is important because it determines fuel consumption, engine durability as well as the emission of air pollutants. Detecting abnormal combustion in spark-ignition (SI) engines is possible by measuring and analysing the engine block vibrations, the ionisation current and the in-cylinder pressure. However, the fundamental variable that provides an in-depth insight into the combustion process is the pressure signal. By analysing the signal, a detailed study of the knock phenomenon can be performed, which is necessary to develop a reliable and efficient knock detection method. By applying the proposed technique, we are able to identify the basic parameters of the pressure trace, such as the starting frequency and the rate of frequency change. By knowing the value of the parameters for various engine operating conditions, the performance of a knock detection system can be improved.