Research On Reliability Assurance Method In Cab Product Development Of Commercial Vehicle

This paper focuses on studying the reliability assurance method for the cab assembly of commercial vehicle.The reliability data of the current commercial vehicle cabs have been collected by means of the market investigation.The current reliability levels of the commercial vehicle cab assemblies and their sub-assemblies have been obtained by means of the data analysis,which provides the basis for determining the reliability goal of the cab assembly newly developed.The method of score allocation of reliability was applied to make the reliability allocation according to the complexity,technical development level,working duration and work environment severity of each sub-system,allocating the reliability goal to each sub-assembly according to the reliability goal of the cab assembly newly developed,providing the basis for their reliability works.The expert team was formed to evaluate the complexity,technical development level,working duration and work environment severity of each sub-system and appropriately determine the scores.In the paper,as an example,the reliability assurance method of a commercial vehicle cab suspension system is studied.Firstly,the reliability analysis tool FMEA is used to analyze the suspension system,with the severity(S),occurrence degree(O),detectivity(D)and the risk priority number(RPN)of each historical fault being determined,indicating that the fault of the highest RPN is the suspension transverse stabilizer rupture.It is decided to perform the reliability improvement work with eliminating the fault mode as the goal.The rig durability test of the cab suspension system is made,in which the fault mode of transverse stabilizer rupture occurs.The methods of the finite element analysis,metallographic analysis of the component nick and so on are applied to find the root causes of the fault mode,resulting in the conclusion that the ill control of the welding process factors is the root cause of the rupture.The welding process factors mainly include welding voltage,welding speed,shielding gas type.Taguchi orthogonal experiment design method is used to determine the best combination of the factors,with which the prototype components are manufactured.The cab front suspension transverse stabilizers are mounted on the commercial vehicles,whose running reliability tests are performed on the Xiangyang proving ground,without the rupture mode occurring.The commercial vehicles with the transverse stabilizer have been put into market in a small-lot,without any feedback of the stabilizer rupture up till now.All these indicate that the reliability assurance method applied for the transverse stabilizer is effective,with the reliability goal being attained.Thus,the reliability assurance method adopted in the paper not only have theoretical basis,but also is practical,which is suitably applied in the enterprises.