Research On The Proportional Relay Valve For Differential Braking Strategy Of Commercial Vehicles

Commercial vehicle is an important means of transportation in modern society.Due to the high quality and high center of gravity of commercial vehicles,traffic accidents such as rollovers and rear-end collisions often occur.Commercial vehicle differential brake control module can effectively improve braking performance and reduce the incidence of accidents.It adjusts the pressure of each brake chamber through the proportional relay valve to compensate for the braking state of the vehicle and ensure the steady running of the vehicle.The proportional relay valve is not only a pressure regulating element in the air brake circuit,but also an actuator of the differential brake control module for commercial vehicle.Its performance directly determines the performance of the entire braking system.This paper presents a new type of proportional relay valve design scheme for commercial vehicle differential brake control module,and verify the design scheme through a combination of theoretical analysis and experimental analysis.Hence,the major studying contents of this thesis are as follow:(1)Comprehensive analysis of domestic and foreign standards and regulations related to air braking system and pneumatic pressure regulating valve for commercial vehicles.Then determine the functions and performance requirements of the proportional relay valve for differential brake control module,and determine the design goals of the proportional relay valve,and provide the basis and reference for the research work of the proportional relay valve.(2)Based on the functions and performance requirements of proportional relay valve,a new type of proportional relay valve body structure design scheme is proposed.The proportional relay valve body mainly includes an increase/decrease high-speed on-off switch valve and a pilot pressure regulating valve,and then the key parameters in the valve body structure of the proportional relay valve are analyzed by a combination of mathematical modeling and software simulation.By analyzing the pressure characteristics,return characteristics and sealing characteristics of the increase/decrease high-speed on-off switch valve,the optimal value of different half conical angle of valve is calculated.By combining the orthogonal test design method with AMESim simulation,the optimal combination of key parameters of the proportional relay valve body is calculated.(3)Based on PID and PWM control methods,the control algorithm of the proportional relay valve is analyzed.Then set the fuzzy controller and formulate the corresponding fuzzy rules to optimize the control algorithm.Using Matlab/Simulink and AMESim for co-simulation,the optimized control algorithm is tested.By testing the time domain and frequency domain characteristic of the control algorithm,this control algorithm is verified.(4)Refer to the test standards and regulations to establish a dSPACE-based hardware-in-the-loop test platform,which mainly includes the substitution model of proportional relay valve body,testing circuit and dSPACE control circuit board etc.Using the hardware-in-the-loop test platform to test the function and performance of the proportional relay valve,the correctness of the design scheme of proportional relay valve body structure and control algorithm is verified.The thesis research work proposes the theory support for proportional relay valve research,and provide references for proportional relay valve design and optimization.