Research On Fault Diagnosis Technology Of The Marine Multi-cylinder Diesel Engine Based On The Instantaneous Speed

There are a wealth of information which can reflect the mechanical power exportation ability of cylinder used in diesel engine in the instantaneous speed signal. And the advantages of convenient measurement and simple make that the application of the fault diagnosis technology based on the instantaneous speed is highly regarded. In recent years, much work has been done on the fault diagnosis technology of diesel engine based on the instantaneous speed in foreign and home. However, the application of the instantaneous speed mainly focus on the inline diesel engine of the larger ignition interval, and are less effective for the V-arrangement16-cylinder diesel engine of the smaller ignition interval. This is due to each feature which is reflected in instantaneous speed signal may be coupled to a plurality of cylinders. So it is difficult to distinguish between the cylinders, which is the fault location and to indentify it. In this paper, the application of the instantaneous speed of the V-arrangement16-cylinder diesel engine is researched. The main content of this paper is as follows:Firstly, the measurement method of the instantaneous speed is investigated, and the measurement system of the instantaneous speed is constructed in the paper. By analyzing the characteristics of the original signal of the measured flywheel end, the method of digital filtering is used to pre-process the signals. And the zero-method and the demodulation method, whose calculation principle are different completely, are used to prove the validity of the waveform shape analysis based on the instantaneous speed.Secondly, several characteristic parameters, which are commonly used, are extracted based on the instantaneous speed waveform obtained above. And the diesel working state is evaluated. By analyzing the result, the reasons of the poor application effect is found for the V-arrangement16-cylinder diesel engine. Furthermore, the characteristic parameters which can better reflect the diesel working state are proposed based on the analysis results such as trends of the peak and valley of the instantaneous speed, the instantaneous angular velocity and angular acceleration by averaging method. At the same time, the application conditions of these characteristic parameters are pointed out.Finally, the method of statistical analysis is used to determine the characteristic parameters, which can represent fault severity, based on the premise that we can pinpoint the fault cylinder location. Combined with the above analysis, the diagnosis model is establish, and the accuracy of the model is verified by experimental data.