Injection fault detection of a diesel engine by vibration analysis

Abstract

In this paper, the potential of vibration analysis for early detection of fuel injection faults in an internal combustion diesel engine, having six cylinders in line, has been investigated. The main sources of vibration of a diesel engine, as well as the mechanism of propagation of these sources to the engine structure have been presented. Using the tarring screw of the injector, the injection pressure in one of the cylinders has been gradually reduced from its nominal value, respectively, by 10 and 50%. Two signals are acquired using an analog-to-digital dynamic acquisition card. The first is the TDC signal in cylinder 1 measured using an inductive sensor. The second is the vibration signal which has been measured, on the cylinder head of the engine using a piezoelectric accelerometer. The vibration signal has been analyzed in the crank-angle domain, the frequency domain using the Fast Fourier Transformation, and in the angle-frequency domain using the Short Fourier Transform. The analysis of the injection fault signals in the three domains showed that in the crank-angle domain, a visual analysis gives limited information; in the frequency domain, the identification of the cylinder with the faulty injector is not possible; and in the angle-frequency domain, the detection of the injection fault and the identification of the faulty cylinder are possible and not complicated.