Modeling and Experimental Study of Relay Valve of Tractor-Semitrailer

U463.5; An improved modeling methodology,considering heat change,friction and inertia of components,is proposed.The relay valve used in tractor-semitrailers is taken as an example to develop the mathematical model.The resulting simulation for time lag,developed based on this model,is validated by experiment.The results show that the time lag of this relay valve is 0.12 s while the experimental value is 0.131 s,which means that the response time can be simulated accurately.The comparison between simulation and experiment also shows that the main factor affecting the response time of the relay valve is the movement time of the internal piston and valve head.These results indicate that the model of the relay valve is effective,and the modeling methodology is verified.This research could provide reference for related studies.