| As the core part of the car, gearbox plays an important role in transforming the speed,increasing the output torque and maintaining the engine in favorable conditions. Itsperformance directly determines the quality of the car. Analyzing and testing theperformance of the gearbox is one of the key links to ensure the quality of automobile.There are a variety of analytical methods based on the characteristics of the gearboxvibration testing, of which velocity method is an important one. In this thesis, the authorwill give a comprehensive study on this important method of assembly-vibration velocitymethod.This thesis first describes the significance of the gearbox quality testing and analyzescurrent status and trends of the development transmission fault diagnosis technology both athome and abroad. Then the author does a detailed analysis on gearbox failure and its causeof the high failure rate parts-gears and bearings, as well as the spread of noise and thepossible propagation path of the noise.Besides, the author also describes sound metrics which leads to the sound intensitymethod and the vibration velocity method. The detailed analysis of the finite plate and aninfinite plate radiation case has also been finished, which generates the relation between thesurface vibration velocity and noise sound pressure in the far-field. Velocity-based methodof noise measurement, the measuring point is particularly important. Therefore this thesisdoes a simplified study of the gearbox of noise and vibration measurement points. Thevibration velocity method can be used in the on line quality testing of after simplified themeasurement points.Finally, the author conducts a test on the velocity method of two random sample ofgearboxes, drawing on the performance test method of gearbox at home and abroad as wellas described in this thesis. After analyzing the data, this thesis comes to the conclusion thatthe vibration velocity method is practical and valid in gearbox fault diagnosis. |
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