| Automotive dual-tube shock absorber is one of the important parts of the automotive suspension, which is related to vehicle ride comfort as well as the vehicle handling and stability. And some shock absorber have abnormal noise in service, which have an adverse influence for vehicle performance of NVH, and cause customer complaints repair, to manufacturer caused additional losses.This topic put forward the abnormal sound of shock absorber detection method on test bench through, using the way of the combination of the shock absorber road test vehicle and bench test. Through the shock absorber parts modal analysis, it is found out that the contact between internal structure of shock absorber and abnormal sound of shock absorber, and methods and ideas is provided about abnormal sound of the absorber of control and governance. Finally, the simulation tests are carried out, and the abnormal sound of shock absorber control method is put forward.(1) The road test of shock absorber is carry out, through which shock absorbers with abnormal noise are divided into three types using signal analysis, sound playback and noise Subject Assessment. And analyzing the related factors about the abnormal noise of shock absorber, the axial vibration of shock absorber piston rod which existing285Hz spikes in frequency domain is found directly related to the abnormal noise of shock absorber, which cause the vibration of the vehicle body nearby. After the road test, the bench test of abnormal noise of shock absorber is carried out, whose aim is to find the detection methods of the abnormal noise of shock absorber. So the bench test condition, test detection methods, data processing format and evaluation index are put forward.(2) In order to find out the structure which causes the abnormal vibration axial piston rod of the shock absorber, the modal analysis of the component of shock absorber is applied. Through the comprehensive calculation of modal analysis of all part of shock absorber, the component "piston+the piston rod+fixing device" of shock absorber is selected as analysis object. So the cause of the abnormal noise is much clearer. And further explored, found that when compression travel is over, rebound stroke is just start, there will be an impact. And when the impact is strong enough, it wills incentive the shock absorber structure produce the axial vibration of shock absorber piston rod of285Hz, and then transfer to the body, stimulate the body vibration, eventually passed to the cab and then sensed by the passenger.(3) Finally, using the software AMESim, the simulative bench test is carried out, the sensitivity of influence factors which is related to the abnormal noise of shock absorber factors is researched, and put forward the way to control abnormal noise of shock absorber, then evaluating the effect of the approach using simulative bench test.There are several innovative points in this topic:(1) Putting forward the abnormal sound of shock absorber test bench detection technology standards through the way of the combination of the shock absorber of road test and bench test. This technology standard has been applied in practical production inspection, and in domestic belongs to be advanced.(2) This subject will split vehicle NVH performance into subsystems, and combine the estimation of acoustic comfort performance with part performance, realize the vehicle and parts connected synchronous design, make practical application easily, reduce the difficulty of the design.(3) Through the modal analysis method, the related concrete structure factors corresponding with abnormal sound of shock absorber is found, and through the simulation of effects of the structural parameters, providing directions of abnormal sound of the absorber control.This research is refers to abnormal noise of automotive dual-tube shock absorber, the cause of abnormal sound of shock absorber is found out, and the bench test method and the control methods is put forward. It has certain reference significance. |
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