Modeling And Optimization Of Pneumatic Braking System Of 6×4 Semi Tractor Based On AMESim

Semi-trailer as one of the main tools in the development of Chinese transportation industry,it plays an important role in promoting the development of logistics and economy.Under high speed and heavy load driving conditions,it is easy to lead to the occurrence of major traffic accidents,among which the traffic accidents caused by braking problems are the dominant factor.Pneumatic braking system has been widely used in semi-trailer because of its advantages of large braking torque,no pollution in working medium,simple structure and so on.However,due to the long wheelbase of the semi-trailer,the far transmission path of the braking gas and the compressibility of the gas,the dynamic response of the pneumatic braking system lags behind,and thus affects the braking performance and driving safety.How to improve the performance of the braking system is one of the key problems that Oems pay attention to.In this paper,a 6×4 semi-trailer is taken as the research object,aiming at the shortcomings of the current pneumatic braking system,based on the pneumatic transmission theory and virtual simulation technology,the key components of the pneumatic braking system and the system model are built by AMESim.The DOE test data model was constructed based on Isight software,and the pneumatic braking system was optimized with dynamic response time as the optimization objective.The Trucksim vehicle model was used to verify the optimization effect.The main research contents are as follows:(1)Referring to the relevant parameters of the braking system of a certain 6×4 semi-trailer,the relevant calculation and selection of the brake and brake chamber were carried out again.Based on AMESim software,the main component models such as brake valve,relay valve,ABS solenoid valve and brake chamber are built.According to the control logic principle of brake system,a complete pneumatic brake system model is built.According to "GB 7258-2017 Motor Vehicle Operation Safety Technical conditions" and "GB 12676-2014 Commercial Vehicle and trailer braking system Technical requirements and test methods",the performance of the model was verified.(2)In order to obtain the influence laws and sensitivities of the structure and size parameters of key components on the dynamic response characteristics of the braking system,the effective working range of each size parameter is defined,and the batch processing program of AMESim is designed to obtain the influence laws of different parameters of the brake valve,relay valve and brake pipeline on the dynamic response characteristics of the braking system respectively.The parameters that have a great influence on the dynamic response characteristics of the pneumatic brake system are the piston diameter of the upper chamber of the brake valve,the piston diameter of the intake valve,the exhaust clearance,the piston diameter of the lower chamber of the brake valve,the piston diameter of the intake valve,the control piston diameter of the relay valve,the area of the intake port,the diameter of the intake piston and the connecting pipes between each component.It provides the basis and data support for optimizing the dynamic response time in the later stage.(3)According to the sensitivity of key component parameters,12 optimization design variables such as lower chamber piston diameter of brake valve and control piston diameter of relay valve were determined,DOE test design was carried out,and multi-island genetic algorithm was used for system optimization.The results show that: After optimization,the pressure response time of the front brake chamber is shortened by 0.11 s,and that of the rear brake chamber is shortened by 0.16 s,and the pressure response time of the front and rear brake chamber is shortened by 21% and 28%,respectively.By building the co-simulation platform of AMESim,Trucksim and Simulink,the optimization results are verified.The results show that:When the initial braking speed is 30km/h,the braking distance is reduced by 0.58 m,the braking time is reduced by 0.38 s,and the braking distance and time are reduced by 5%.When the initial speed is 80km/h,the braking distance is reduced by 3.96 m,the braking time is reduced by 0.12 s,the braking distance and the braking time are reduced by 6% and 7% respectively.By studying the dynamic characteristic response of pneumatic braking system,the braking response time and braking distance are effectively shortened,the incidence of traffic accidents is reduced to a certain extent,and the driving safety is improved.At the same time,the key component model construction and system integration method of pneumatic braking system are studied.In addition,the research idea of taking dynamic response characteristics as optimization objective,using multi-island genetic algorithm for optimization solution,and combining with Trucksim vehicle model verification of optimization results,provides technical reference for forward research and development and optimization design of vehicle braking system,which has certain practical value.