Fault Diagnosis Of Automobile Engine Power Perfermance And Work Uniformity Based On Instantaneous Speed

According to its fuel, Automobile engines can be divided into diesel and gasoline.Diesel engine is the most commonly powered mechanical equipment, are widely used in oil field, fixed power generation, railway traction, engineering machinery and various areas of the ship. Because of its complex structure and poor working conditions, and thus the failure rate is very high. Diesel engine as power machinery, and its running status directly affect the working conditions of complete sets of equipment. Therefore, proceed fault diagnosis in real time to the state of the diesel engine, and ensure the equipment running at its best state in every moment, and it's necessary to improve the quality and efficiency of maintenance of equipmentA lot of diesel engine fault detection method, including:particle detection, acoustic shock detection, thermal parameters detection. The issue using thermal parameters detection method to diesel engine fault diagnosis. By the instantaneous rotational speed detection, analysis and processing, using the instantaneous speed fluctuation method of fault diagnosis method to achieve the outside characteristics and work of uniformity of diesel engine. Unified Visual C++ and MATLAB of their respective strengths, diesel engine fault diagnosis system should be programmed in Visual C++ and MATLAB environment. Finally, through Visual C++ and MATLAB's interface program to achieve the connection.The issue includes the following work:1. The data processing and diagnosis of external characteristicsThe external characteristics representative of the highest dynamic performance of the diesel engine, external characteristic show that the relationship of the effective torque of the diesel engine T, effective power P and the corresponding rotational speed n. We can calculated and processed the data of the instantaneous speed in the Visual C++ environment.Matlab has a strong graphic display function. In Matlab,we can use the method of curve fitting to draw the speed-power and speed-torque curves.And compared the two curves with the standard power and torque curve.according the two curves which trends and the degree of close to the standard curves to judge the running status of the diesel engine is good or not.2. The data filtering and diagnosis of Work uniformityWe analysis and processing the data collected from the lower machine,and to calculate the instantaneous speed.The experimental results of the instantaneous speed have many interfering signals.first.strong interference in the signal should be eliminated.and then filtering the data of the instantaneous speed.In Matlab,we can filtering the data in time domain ang frequency domain.In time domain,we can use the FIR filter based on window function to proceed these data,and select the Hanning window.In frequency domain,we can use all-phase filter to proceed those data,and then draw the filtered waveform and display it.The next step for feature extraction,which extract the maximum value and the minimum value of each cylinder. Finally,we can achieve fault diagnosis of the work uniformity through analysis of time domain and frequency domain.3. Serial communication of the fault dianosis systemBy the way of serial communication,we can uploaded the data of lower machine and saved to the specified folder in the host computer.In host computer,all document should be read.in Serial communication part,we use the way of MSComm to realize the data transmission between host computer and lower machine,the data collected from lower machine transmit to host computer through serial port,also in the form of ten working cycle data for a group saved to the specified folder.Then through Visual C++ programming to realize reading,calculating and processing the uploaded data.4. The connection of Matlab and Visual C++The connection of Matlab and Visual C++ use the way of Matcom,the m file edited in the Matlab environment generated to.cpp file and.h file through Matcom, copied the Matlab libraries Matrix <Lib> files and those two files to the directory of the Visual C++,and added those to the project.Add response function to the Visual C++,to realize Visual C++ called the m file.