| The automobile industry has been the support one of our national economic development. In the research, it is considered that the parameters of vibration and noise brought by the motional car is one of the most important guidelines and it affects the passengers' comfort, as well as the drivers' safety in the cars directly. The vibration and noise of the automobiles mostly comes from the engine and transmission system. However, automobiles' transmission system is mostly comprised of derailleur. So it shows the especial crucial significance to knock down the vibration and noise of the whole car, by depressing the vibration and noise resulting from the derailleur. With complex structure of automobile derailleur, variety of the transmission component, long transmission distance, and the combined effect between the transmission components in particular, the vibration signal consist of the complex frequency distributions, which add the difficulty in malfunction diagnosis, such as different characteristic mechanism of vibration malfunction, diagnosis method and principle, and malfunction discernment, etc. Besides these, there is some difficulty in gaining malfunction signal acquisition, therefore, it is believed that it is impossible to reckon on only one or two methods to gain the information of malfunction signal and resolve the problems.Base on retrospect of all the national and oversea progress in the automobile derailleur vibration and noise research, whether in the past years or nowadays, the following work is carried out:First, the blue print to test the vibration and noise of the derailleur is marked out. The spot testing and analysis by synthesis is adopted to analyze and process the test signal.Second, the dominating factor of the vibration and noise occurring in the automobile derailleur is analyzed, and the research on the transmission mechanism of the influencing factor is also carried through. As a result of these, the trait of the vibration and noise induced by all of these influencing factors is summed up.Third, the eigenvalue of time domain signal, wave filtering analysis, frequency chart analysis, frequency chart subdivision analysis, demodulation analysis, etc, all of these the analysis by synthesis methods are adopted, and typical malfunction is analyzed on emphases, too. After this work, the trait information of the typical malfunction is acquired.In the end, the article analyses and processes the experiment data with the help of the Dynamic Signal Analysis and Fault Diagnosis System (DASJ).After the analysis and research work, the following conclusion can be drawn:The first of all, the close sound filed noise test can be used to eliminate the affect of other environment noise in the producing locale noise test.Besides this, the vibration and the noise signal of the same derailleur are correlative closely. In order to reduce the noise of the derailleur, it is necessary to improve the strengthof the strength to minish the vibration.Thirdly, the fact that the inherent frequency will be stirred and the noise comes into being as result of the derailleur shell radiation when the mesh frequency of gear mate is close to the 1/2 or 1/3 of the inherent frequency of the derailleur box, is discovered.Fourth, in order to avoid the resonance, the dynamic property analysis should be done to make the working frequency of all the movement parts apart from the inherent frequency of the derailleur box when the automobile derailleur is designed.Finally, for the full closed gearbox, the noise is mostly brought by the derailleur shell radiation when the derailleur box vibrates. So, it is reasonable to devise the structure of derailleur box properly to reduce the derailleur noise.To sum up, the ten automobile derailleurs are tested in the different working condition and velocity ranks, and the test signal is also processed and analyzed. In the meantime, the diagnosis result is given and proved true by the validation. |
