The Failure Detection Technology Research On Automatic Brake Adjuster

The automatic brake adjuster, installed on the input side of S camshaft, isworking to compensate the brake clearance which caused by the wear of brake pad.The reason why the failure of automatic brake adjuster inevitability is that theworking conditions and stress factors are considerably complex. The failure detectionof automatic brake adjuster can predict and avoid the case of brake failure happeningtimely. However, the existing failure testing equipment both home and abroad arehardly to qualify the online failure detection and the fault source lookup as well asfault diagnosis, which is limited by the effective method of mode design and theprecision technology of the test equipment. In view of these reasons,we put forward afailure detection technology of automatic brake adjuster based on the failure model,and the four main research contents are showed as below:Firstly, build the fault tree model of automatic brake adjuster based on FTA method.We predict the failure event of all the18parts of automatic brake adjuster accordingto FTA model, and the durability test bed of automatic brake adjuster is used to getthe statistics of failure probability of all the18parts of automatic brake adjuster, andfurther know the HSC Unit and the OWC Unit are the easy failure unit of automaticbrake adjuster.Secondly, build the HSC Unit failure model and the OWC Unit failure model. TheHSC Unit and OWC Unit model was build according to the principle of automaticbrake adjuster in the real vehicle test condition and the mechanical properties and thematerial properties. What’s more, we can predict the critical state of failure accordingto such the two failure model and its limiting value.Thirdly, build the Computer Failure Simulation Analysis Model(CFSAM) of HSCUnit and OWC Unit based on ANSYS Workbench finite element simulation platform.With the help of high speed operation system of computer, all the failure performanceparameters and failure data clouds can be calculated by importing the dynamicparameters as separating force, separation and adjusting brake moment in real vehicleconditions.Fourthly, a failure detection device of automatic brake adjuster is designed based onthe failure models of HSC Unit and OWC Unit. This failure detection device includesa precision loading module and a Automatic assembly module. In addition, the failure detection device is controlled by LabVIEW program. Meanwhile, the algorithm ofseparation extraction based on the Radon transform is specially designed to improvethe detection accuracy of dynamic testing system. The failure detection device is acompletely simulation working environment based on real vehicle condition is aimingto decrease the dynamic errors of the testing paraments effectively. The failuredetection device has the ability to obtain the dynamic paraments such as separatingforce, separation and adjusting brake moment, which the failure models of HSC Unitand OWC Unit needed. This method, obviously, can judge the failure source amongthose18parts and evaluate its extent of damage for automatic brake adjust.In addition, single group experiment is conducted for the failure detection methodbased on failure models. Through the experiment, the measurement capability indexes(C g,Cgk)of this failure detection device are over2. As for the improvement of theaccuracy, the computational error of the linear Radon transformation is over10timeslower than the gradient maximum optimal method. In addition, the failure detectiontechnology based on failure model has been successfully used in Hangzhou Woleitech. Co., LTD., and it has a significant engineering application value.