| Bus air brake uses compressed air as braking force transmission medium,which converts air pressure to the wheel braking force,so as to realize bus to slow down.Pneumatic braking system is widely used in bus for its great superiority braking performance.Braking system is one of the important systems of bus.It can accurately grasp the characteristics of the parts of the braking system,which has great significance to improve the braking performance.The working processes of the bus air braking system including pressurization process,pressure holding process and decompression process.In decompression process,due to the influence of the braking system response lag,there is pressure response delay.Quick release valve as a key component of the decompression process,pressure response time is too long can affect the bus speed up.Not only affect the bus moving efficiency,but also the safety,so it is necessary to research the pressure response of the quick release valve.The paper takes the method of theoretical,simulation and experimental researching the pressure characteristics of quick release valve.The main works of this paper are summarized as followed:(1)Through the survey and literature,analysis of current research situation of bus air braking system and relevant components.Understanding the pressure transmission theory,the working principle of bus air braking system and the quick release valve structure,etc.(2)On the basis of relevant theoretical,analyzing the action principle of quick release valve.Establish the pressure characteristics mathematical model of quick release valve.The mathematical model mainly consists of diaphragm motion equation,the quick release valve outlet flow characteristic equation,the chamber pressure response equation and the diaphragm deformation force equation.(3)Based on theory analysis and the established mathematical model,build on the MATLAB/Simulink simulation algorithm and analysis the results.(4)Build the pressure characteristic test bench of quick release valve referring to the national standards and industry standards,and test data are obtained.Contrast test and simulation data of quick release valve pressure characteristics obtained,to verify the accuracy and reliability of test and simulation.(5)Combine the test and simulation data,analyze the influence factors of the quick release valve pressure characteristics.Main factors including exhaust tone gap length,the diameter of interface,the diaphragm thickness and the installation location and so on.From the pressure response time and stability,this thesis study the pressure characteristics of quick release valve and its influence factors.This provides a reference for design and selection of quick release valve and it is helpful to improve the bus air braking performance. |
