Design And Characteristics Of The Relief Valve Without Pressure Overshoot

Pressure relief valve is a very important component,which is used in almost every hydraulic system,it’s mainly used to limit the system’s pressure to a constant value or prevent hydraulic system overloading.The performance quality of the relief valve has a great influence on the entire hydraulic system and therefore it’s significant to study the relief valve.This paper elaborates the development of the relief valve,and it’s research status at home and abroad,and the key issues in present study.Introduce the RPET type relief valve,which is produced by the SUN Hydraulics corporation of the United States,describe the composition of the relief valve and it’s working principle of realizing the dynamic response process without pressure overshoot,and study the characteristics of the relief valve without pressure overshoot in this paper by making the RPET type relief valve as an object.This paper includes four parts:(1)According to the requirements of the project,the rated flow of relief valve without pressure overshoot is50L/min,and it’s rated pressure is16MPa.Then,according to this requirement,design and calculate the relief valve,preliminary obtain major dimensions;(2)Build dynamic model of the relief valve in AMESim software,simulate and analyze the effects of structural parameters such as orifice diameter,sensitive cavity volume,the stiffness of spring and seat hole diameter,etc on relief valve’s dynamic characteristics,and then optimize the related structural parameters;(3)Theoretically analyze the relief valve.Establish the relief valve’s static mathematical equations,and then linearize the equations at a steady-state point of the relief valve,analyze the linearization equations and achieve the factors which have great impact on the relief valve’s static properties,simulate the relief valve’s stable pressure under different flow rate by using AMESim,and obtain the effects of related parameters on relief valve’s pressure-flow rate characteristics,then calculate the relief valve’s unlock ratio;(4) For RPET type relief valve existing the disadvantages of larger pressure regulator deviation and smaller unlock ratio,analyze the main reasons are the orifices’layout of the relief valve and the steady-state flow force of the main poppet valve,then,improve the structure of the relief valve according to these two points.For the layout of damping holes,change the RPET type relief valve’s two-damping holes’layout structure to the three-damping holes’layout structure,through theoretical analysis and AMESim simulation,the relief valve with three-orifice layout structure is proved better dynamic properties,which can realize zero pressure overshoot during dynamic process,and has smaller pressure regulator deviation and larger unlock ratio; for the steady-state flow force of the main poppet valve,compensate the flow force by adding flange structure to the main valve,and the rationality of the new structure is verified by theoretical analysis and CFD simulation;(5)Analyze the factors that have influence on the pressure rise time,then optimize them by using orthogonal tests and AMESim simulation.