| Diesel engine is a kind of reciprocating machine which is widely used in ships, vehicles, locomotives and so on. As the heart of the power system, its working situation directly influences the safety and reliability of the power system. Because its structure is complex and working condition is very changeable, it has a high possibility of faults. Thermal parameters contain much information of abnormal performance in diesel engine, so they are very important for fault diagnosis. The parameters can be used widely just because they are hardly disturbed by the outside situation. However, the relation between malfunctions and thermal parameters is not simple, and the knowledge about the relation, which we can get, is mainly from experimentation and the accumulation of working experience. Depriving the fault information in an economical and accurate way becomes a hard problem for fault diagnosis. With the development of the calculation method of diesel working process, fault simulation becomes an efficient way to solve the problem.Firstly, the paper introduces the state of the art of fault simulation and diagnosis in diesel engine and presents the main task of the research in this field.Secondly, the paper analyzes abnormal performance in diesel engine according to engine structure model and function model. The system of diesel engine is divided into several subsystems, such as Inlet tube, Cylinder, Exchange tube, Turbo charger. All these subsystems are zero-dimension system. After the above work, a universal zero-dimension fault simulation model of diesel engine is built.Thirdly, according to the constructed simulation model, a faults simulation software is developed in the environment of Visual C++ 6.0, which can simulate some typical engine malfunctions, such as leakage, block, time-sequence error and have a friendly simulation interface. Through fault simulation database and simulation curves of thermal parameters, abnormal variation of thermal parameters can be seen clearly.Fourthly, different engine malfunctions under different grades are tested on the simulation software. The result of simulation indicates the inner relations between engine malfunctions and abnormal thermal parameters, thus providesuseful reference for fault diagnosis.Lastly, experimentations are carried out on Chaochai 6102BQ engine and the data of the thermal parameters according to different oil-apply lead angle is derived. The influence of the change of oil-apply lead angle on the rate of heat release is researched, then a reference is provided for building an accurate heat release model. |
