The Research And Development Of The Engine-testing System

The engine-testing is an essential part when conducting engine production and research. We can analysis the engine power, economic and improve the performance of engine according to study engine characteristic.Further,It is important for data processing to test engine performanct,which is base to comment engine performance indicators.The paper studies the software of the test system on the base of the experiment flat,combined with the research project of engine test-bed experiment.In this paper, a set of engine testing system software are developed by C# language,utilizing Object-Oriented Program.First, the structure and function of the system are introduced.Besides,the basic measurement principle and methods of engine performance testing parameters were also analyzed.On this basis, the software structure of the system were built.The paper developed a multi-UI includes virtual instrument ,virtual waveform and so on, at the same time,realized the functions such as date collection and analysis, real-time display, alarm, fitting curve ,data base and etc. studied the data pretreatment,including data format validation and data abruption. Besides,The communication formats between the bottom and the host computer was analyzed detailedly.This article focuses on analysis of the data processing method.In order to enhance the precision of data processing ,the method of rejection for outliers is researched theoretically and analyzed by experiments. The research succeeds in getting rid of the big error by Grubbs'criterion.The systematic error is eliminated by adjusting instrument zero,then the paper adopted the least square wise polynomial fitting method to fit curve. Taking into account the measured value being lost or transiented and other factors, the characteristic curve fitting equations were obtained by two and three sub-spline least-squares since it is not accurate to fit all the data only using a polynomial curve.The connection and smoothness of all sub-points were realized according as functions are equal in the demarcation point,as well as the first and second derivative. The alteration with the speed was obtained about torque and fuel consumption rate with the speed - torque and speed - fuel consumption rate curve test.The test shows that the test accuracy improve with sub-least-squares method after comparing the the relative error of fitted values of the two methods. The simulation also proves that this new curve fitting method is right and effective.The paper is based on the theory, with derivation of a mathematical model,discussion ways of theory and realization of system,which make it significative.