Design Of An Automatic Pressure Regulating Valve For Bus Air Braking Circuit

Air braking system is widely used in the braking process of buses and trucks.The pressure regulating valve is an important part which used to control and adjust the pressure of the commercial vehicle air braking circuit.The range of the braking torque is determined by its pressure regulating range,the braking distance is restricted by its pressure response characteristics,and the bus braking stability is influenced by its pressure and flow-rate characteristics.Therefore the performance of the pressure regulating valve is directly related to the performance of the bus braking.In this paper,based on the demand of automatic pressure regulation of air braking system,the design of an automatic pressure regulating valve for the bus air brake circuit is studied from three aspects: the function design,the performance design and the structural design,and it adopted these methods of theoretical analysis,mathematical modeling and simulation analysis to verify the rationality of its performance and the feasibility of the design.The main works of this paper are summarized as followed:(1)Based on the research of bus air brake system,the composition and working principle of air brake circuit,as well as the function of pressure regulating valve in the whole brake process are analyzed.Through the analysis of the air brake performance,it is concluded the influence of each pressure regulating valve's performance index on the brake system,and summed up the demand of automatic pressure regulation of air brake circuit.(2)In this paper,it is studied on the integration,automation and intellectualization of pneumatic products.From the angle of improving the bus brake performance,the function analysis of the automatic pressure braking valve is completed.In addition,based on some relevant national and international standards of the brake system and pressure regulating valve,according to the demands of braking performance for automatic pressure regulating valve such as: pressure regulating range,response characteristics,pressure and flow-rate characteristics and other relevant characteristics,so as to complete the design and analysis of the new valve.(3)It is designed an overall structure of an automatic pressure regulating valvefor bus air brake circuit,which used the pilot-operated precision pressure regulating valve as the main valve body,used the cam mechanism as connection mechanism,used the stepping motor as the driving mechanism,and adopted an driving control module which integrated CAN bus.This valve can be integrated into the CAN bus communication network,and would realize the automatic and precise controlling of the output pressure.(4)According to the structure design and the principle analysis of the automatic pressure regulating valve,its working process can be divided into three parts,which included the electromagnetic part,the valve core moving part and the air transmission part.On the basis of the mathematical model,this paper analyzed the movement characteristics of the valve core,pressure response characteristics,pressure and flow-rate characteristics through MATLAB/Simulink,so as to verify the rationality of the automatic pressure regulating valve's performance and the feasibility of the whole design scheme.In this paper,according to the integrated structure,a new kind of automatic pressure regulating valve is designed.Which has great significance to improve the performance of the air brake,ensure the safety of the vehicle,and improve the traffic situation.