Research Of Structure And Characteristics Of Screw-In Cartridge Counterbalance Valve

Screw-in cartridge valve has some advantages of simple structure, equipped with pieces of standardized, easy to replace and so on. So it is being widely used in hydraulic lifting system of engineering machinery. With the rapid development of computer simulation technology in the global scope, digital simulation technology based on computer has replaced the traditional time-consuming testing methods and become the preferred means of home and abroad hydraulic pressure valve design.As the key element to provide back pressure in balance loop, hydraulic counterbalance valve is proverbially used in engineering machinery, especially in the lifting equipments.In the case of negative load conditions, system needs to produce enough pressure drop in the hydraulic actuator return port to overcome the load power. If so, it can ensure the implementation of components to decline smoothly and improve balance loop stability. In this thesis, the author chooses a screw-in cartridge counterbalance valve as the prototype and completes key structure design, flow field simulation, dynamic characteristics analysis and structure optimization. Main contents are as follows:1. analyses the influence of pilot ration and back pressure on counterbalance valve through theoretical calculation; calculates the key oil port diameter according to the initial setting pressure, maximum load pressure and generalized flow values; designs throttling groove for spool according to the different working conditions.2. builds 3D simulation model for the internal flow field of screw-in cartridge counterbalance valve; completes the steady state calculation of mesh through the CFD software FLUENT; analyses the disadvantages of structures design and based on pressure contours and velocity contours in the calculation results; improves the structure of screw-in cartridge counterbalance valve and contrasts simulation result. Finally gains reasonable structure of valve spool and valve stem; improves the working performance of the orifice.3. establishes the static and dynamic mathematical model of screw-in cartridge counterbalance valve and calculates the function of the relationship between the control pressure and load pressure under flow remains unchanged; creates AMESim simulation model for screw-in cartridge counterbalance valve and its basic balance loop based on dynamic mathematical model; gains the pressure, flow, speed and displacement curves in the initial conditions and verifies the accuracy of the model by these curves; simulates and analyses the influence of some important parameters, which includes load mass, spring stiffness, orifice diameter and cone angle for counterbalance valve and its balance loop.