Evaluation Of In-cylinder Working Process For Diesel Engine Based On PSO-SVDD

The essence of the diesel engine working process is to accomplish two energy transformations in the cylinder whose result determines the performance of the engine.The in-cylinder gas is the energy transformations medium and the in-cylinder pressure changed data to relative crank angle,the p-φindicator diagram or the p-V indicator diagram to the cylinder volume,can directly or indirectly reflect the in-cylinder working condition of diesel engine.Therefore,this paper chooses the in-cylinder pressure as the basic measurement data to evaluate the in-cylinder working process of diesel engine.Firstly,the current domestic and international intelligent diagnosis and evaluation methods are studied.Based on the facts of long sampling cycle of in-cylinder gas pressure,the difficulties of obtaining abnormal data,many characteristic parameters and the full usage of the existing monitoring system,this paper selects Particle Swarm Optimization(PSO)Support Vector Data Description(SVDD),a single classification algorithm,making a quantitative evaluation of in-cylinder working process.Then the in-cylinder working process is analyzed in detail,characteristic parameters of each stage’s in-cylinder working process are extracted and the extracting methods are discussed.When it is abnormal,the characteristics of changes,the distribution of corresponding feature parameter and possible causes of abnormalities are studied.According to actual needs,the two algorithms are combined organically.The nuclear parameters and penalty coefficients of the kernel function are optimized by PSO,supported by the structure of SVDD,achieving the optimal performance.Finally,using the above algorithm to construct the evaluation model of in-cylinder work process,combined with the analysis of the distribution of the characteristic parameters,a complete evaluation system is obtained.By substituting the actual ship operating data,the in-cylinder work process is successfully and quantitatively evaluated with the overall score of 85.5 and 85.7 points and the abnormality of the No.3 cylinder is detected.The feasibility of the method is verified.Lastly,the deficiencies in the research process are analyzed and the further prospects are explained.