Automobile Suspension System's Performance Evaluation And Fault Diagnoses

Automobile suspension device not only is the import assembly that assurance ride comfort, but also is the import assembly which promises the car operational stability, the car brake and the car active safety. While automobile move more quickly now, it's drive smoothly and safety performance relate with the quality of suspension device. Along with the road transport condition improve, the drive speed of car is continuously raising, therefore, in order to keep the suspension device in good function, discover suspension device existent problem in time, we should periodically process necessary suspension performance test, and make an objective evaluation.What's more, as an important assembly of automobile, there's still no fault diagnoses system of suspension. If we can find an efficient method to identify the suspension's performance or find out failure part and reason by analyzing the testing results, and then establish the fault diagnoses system. Not only we can make a quick and high efficient testing and diagnoses, but also we can offer very exact and usefull information for maintaining and future's design. So how to make a quick and credible testing to find out suspension's faults and hidden trouble, and make a general and complete evaluation, is an important means to insure the suspension's performance.The thesis has researched on the automobile suspension system's multi-parameters performance evaluation method and fault diagnoses system. The content mainly includes a few aspects as follows:1,According to the request of the performance that drive smoothly and safely, and the possibility of the vibration system signal can collect, the thesis built up car body acceleration, tire opposite dynamic load and suspension dynamic flexvity as the evaluation method of suspension performance experiment. This evaluation method can reflect all automobile suspension performance, better then the one parameter evaluation method.2,The thesis process a necessary simplification to the car vibration system, built up 1/4 car two-degrees dynamics model and mathematics model via LAPLACE transformation of the mathematics model, thesis gets the transfer function, frequency response function and amplitude frequency characteristic of car body displacement, the car wheel displacement, and car body acceleration, car wheel opposite dynamic load and suspension dynamic flexvity to speed inspirit. It also Built up simulation models of sine excitation signal and 1/4 car two-degrees vibration under the Simulink model in Matlab. According to the given parameter of the liner sine excitation signal and this kind of car's structure parameter, the simulation results could well fit for pre-built vibration model and theory analyzing, which proved this model's validity and it's feasibility.3,In order to evaluate the suspension system, the thesis has analyzed the suspension structure parameters'influence to the evaluation parameter, such as car body acceleration, car wheel opposite dynamic load and suspension dynamic flexvity, and these evaluation parameter's response degree to the change of suspension's performance. Use M program, made the amplitude frequency characteristic variable, and then made full evaluation of suspension's performance.4,The thesis also took car body acceleration, car wheel opposite dynamic load and suspension dynamic flexvity as the diagnoses parameter, tried to change these parameters to simulate the fault situation and analyze these parameter's change trend and degree, then built up the fault diagnoses date-base. From the amplitude frequency characteristic of the above parameters, we can identify the vibration signal's frequent component and it's distribution, and every frequent component's amplitude and energy. We can diagnose the automobile suspension system's fault by these curve.5,The thesis has given the test equipments and some necessary sensors'distribution situation, introduced the measure method of car's structure parameter which is necessary for fault diagnoses data-base's building, and evaluation parameter, diagnoses parameter's obtaining method. At the same time, It has also given the vibration signal's treating flow details.The automobile suspension system's evaluation method can make a whole credible performance evaluation, the fault diagnoses system can realize the quick and exact fault diagnoses, which can provide a referrence for optimize suspension parameter's design and under using automobile's suspension performance testing, diagnoses and it's maintenance.