Simulation And Optimization Design Of Pressure Characteristics Of A Commercial Vehicle Service Braking System

In this paper,a 4x2 commercial vehicle of Dongfeng Liuzhou Automobile Co.,Ltd.is selected as the research object,aiming at the response characteristics of the service brake system of commercial vehicles,using theoretical analysis,mathematical modeling,simulation and bench test to carry out research,and the key components of the service brake system are optimized to reduce the braking response time.The main work of the thesis is as follows:(1)Based on the theory of pneumatic transmission,analyze the law of gas flow.According to the process of gas entering and exiting pipelines,gas tanks and other volumetric elements,a mathematical model of the flow characteristics of the orifice is established.At the same time,the structural characteristics and working mechanism of series double-chamber brake valve,quick release valve,relay valve and brake air chamber are studied,and the corresponding differential equations are established.Provides a basis for simulation modeling of pneumatic braking systems.(2)Through the disassembly and measurement of the parts,determine the preload,exhaust clearance,spring rate,mass,area,area of rubber diaphragm and other relevant mechanical parameters and size parameters of the piston and spool in the series double-chamber brake valve,quick release valve,relay valve,brake chamber.Simulation model built on the MATLAB/Simulink software platform.By creating simulation models,the pneumatic braking system can be comprehensively analyzed and evaluated to optimize its response characteristics.(3)Build a bench test according to the national test standards and relevant enterprise standards,study the pressure response characteristics of the pneumatic brake system,and collect and record the data in the test through the data acquisition software.In order to improve the correctness and reliability of the simulation model,this paper verifies the simulation model of each component and corrects the model.At the same time,these works also provide some help for the optimization of the response characteristics of the service brake system.(4)Through the analysis of simulation results and test results,it is found that the pressure response characteristics of the quick-relief valve in the inflation and degassing stages are relatively slow.In order to improve this problem,the orthogonal experimental design method is used to optimize the key influencing parameters of the quick release valve.The optimized solution is 10 mm in diameter,700 k Pa in air pressure and 1 m in connection line.After optimization,the inflation response time is reduced by 50 ms compared to before optimization,and the gassing response time is reduced by 60 ms compared with before optimization.The optimized brake response time of the quickrelease valve meets the provisions of GB 12676-2014.