Research On Monitoring Method Of Torsional Vibration For Diesel Engine

As a "heart" of the ship, the reliability of diesel engine directly related to the ship's security, and the reliability of crankshaft directly related to the safe of the diesel engine as one of the most important components. With the continuously improve of marine diesel power, more and more serious torsional vibration phenomenon appeared in ship diesel and has become a major cause of the diesel failure. As the response of the diesel engine excited by cylinder torque, the crank angle signals can direct reflecting the overall working conditions of the engine, so we can get much useful information about working conditions and faults related to engine by the signals' analyzing and post-processing. It has great significance and application value of engineering for the working condition monitoring and diagnosis of the cylinder by studying the technology with the crankshaft vibration and solving the key technologies of signal measurement and processing. This paper studied the monitoring method about torsional vibration of crankshaft on the new medium-speed diesel engine and large low-speed marine diesel engine, mainly contains the following contents:1) Have an in-depth research to the post-processing methods about Torsional Vibration signal, including the interpolation, the window function, the processing of cycle average and gear average and so on. We could get the accurate measurement results use a smaller sampling frequency through the signal post-processing and reduce the cost of hardware about acquisition system;2) Developed a virtual instrument about Torsional Vibration based LabVIEW and verified its accuracy through experiment;3) Researched the measuring method of angular vibration based on NI acquisition system which has its own advantages such as higher accuracy, lower cost hardware, higher universality and longer duration of surveying, also the angular vibration signal of crankshaft can be measured with other signals synchronized;4) The torsional vibration measuring instrument can collect a lot of working cycles of the diesel, and we can get the accurate fault diagnosis parameters through measuring and analyzing the angular vibration of diesel with stable condition and have the condition monitoring and fault diagnosis by the torsional vibration signal;5) Through the analysis of test results find out that the 0.5 harmonic amplitude values is on the most sensitive state to the diesel engine work, and verified the methods of diesel engine condition monitoring and fault diagnosis which was applied to the misfire fault diagnosis;6) Had a dynamic simulation analysis to the crank linkage of 6L16/24 diesel engine by ADAMS/Engine. Not only verified the feasibility of fault diagnosis based on torsional vibration through the comparison and analysis of the simulation results, but also provided some new ideas and reference for the work Monitoring and fault diagnosis methods of diesel engine.