The Reliability Assessment Of The 5T136 Automobile Transmission

The automobile transmission is the key part of the automobile, and improving the realiability of auto transmission is helpful to reduce automobile warranty cost, product liability damages, maintaining the product costs, the cost of solving the relaliability problems (product design and revision, modify in the manufacture process and so on) These cost savings tend to be considerably more than the reliability work costs.The aim of this paper is to give an assessment to the automobile transmission realiability and analyse the system.And the ultimate goal is to calculate the transmission reliability though the parameter we have got.This paper takes 5T-136 auto-transmission for example to calculate its reliability.This paper divides the transmission reliability evaluation into four parts.(1) This paper gives a failure mode effect analysis to every componment of the auto transmission. And then we find the impact and effect of the transmission conponments' failure mode. We analyse the potencial failure mode of every conponment and then use the critically analysis method to find out the most possible failure parts of the transmission.(2) This paper gives a reliability analysis model of the auto transmission.This model is based on the system-level stress-strength interference model, in the process of establishing this mode we consider each gear components are independent of each other and their failure are related with each other. Besides, the micro and macro uncertainty of load are considered in this model. Finally, the strength degradation with the increasing times of the load influence is also taked into consideration in this model.(3)Aiming to calculate the established reliability model above, frist of all we should make sure the probability density function of the component and the transmission system. According to the result of FMECA of 5T136 auto transmission, this paper analysis the most easily affected componments though the load analysis.So we get the relationship between load and stress of each gear dangerous part. And then this paper uses mathematical software MATLAB to get the result of the model though the known dates and draw the curve of each gear reliability and check weather the model is accurate enough to test the reliability of the transmission.(4) In order to facilitate the application of engineering, we developed a reliability analysis software to the transmission though the function of the Matlab GUI.Though the most potencial failure componment of the auto transmission by FMECA, and design the auto transmission reliability evaluation system though the GUI function in the Matlab.In the main show interface of the software, there consists of six gears mode.And then enter each subsystem, input relevant parameters, we caculate the reliability of this gear. Finally we get the accurate reliability number of the transmission as a whole. As a result, we can give a reference of the auto transmission to the enterprise.