Diagnostic Method for 2-Stroke Cycle Diesel Engine* by Measurement of Vibration on Cylinder-Jacket -Observation of Change in Normal Vibration Pattern-

It is necessary to arrange the system to monitor the operational condition by various methods to achieve the safe operation of the engine. Based on the idea that the information on the engine condition can be obtained from its vibration signal, this paper carries out the experiment of the diesel engine of the actual ship. The vibration was measured for a long time (7800 hours) by means of a vibration sensor on the cylinder jacket. The hand touch can not recognize the time change of the vibration, but the three-dimensional expression of the vibration data through the frequency analysis allows the good understanding of the change of the vibration. The vibration is always changing if the vibration is observed on the long running hours of engine basis even in the stationary operation (engine revolution: 103 rpm) of the diesel engine. We executed the statistical analysis as one method to estimate the condition of engine by the information from the vibration. All the data of vibration was recorded on a normal engine condition, as a result we could not examine on an abnormal engine condition. Thus, the vibration data of low engine revolution (30 rpm) was used as the data of abnormal condition in this analysis. As the result of the analysis, it is found that the abnormal can be recognized from the above-mentioned engine condition. We succeeded to make the statistical model which can diagnose an engine condition.