| Hydraulic valve is the basic element that is widely used in hydraulic system, by controlling the internal fluid movement, such as to change its direction and flow, in order to realize the movement of the actuator. And the spool valve is a form of control valve which is the most used in hydraulic valves.In hydraulic valve, the clearance between valve core and valve sleeve affects the overall performance of the system. If the clearance is too big, the hydraulic oil may overflow, affecting the normal work of the hydraulic system. On the other hand, if the clearance is too small, the operating force increases, and may cause the valve core clamping. The valve core clamping is a common trouble, seriously affecting the normal work of the hydraulic system. In hydraulic valve, due to the throttling effect, the oil temperature rise through the valve port, thus the temperature of the valve will rise. With the temperature rising, it causes the expansive deformation of the valve core and the valve sleeve, which changes the gap between them and may lead to the valve core clamping. To sum up, the study of the temperature and deformation of the hydraulic valve has important practical significance.In this article, three-position four-way valve of Φ8is taken as the research object, and the Pro/Engineer software is used to establish the geometric model and the Gambit pre-processing software is used to mesh, and the FLUENT software is combined to simulate with the ANSYS software. Due to the rising of the temperature of the hydraulic valve is the result of viscous dissipation of oil, to get the temperature distribution of solid, the temperature field of hydraulic oil must be analyzed first. As a result, the flow field analysis of fluid part is simulated first, and then the analysis of the temperature and deformation of solid part.The main content of this paper is as follows:It is expounded that the research status at home and abroad and the basic methods and theories of fluid mechanics. The control equations and turbulence models on the flow field analysis are introduced in short. The three dimensional model of spool valve is established. The pressure, velocity, temperature of oil are analyzed through the use of FLUENT software about CFD, and the pressure field, velocity field, temperature field of the oil are obtained under different working conditions. In combination with the hydraulic oil temperature field through the analysis of the flow field, the temperature field and the deformation of the valve core and the valve sleeve are analyzed on the Workbench platform of ANSYS software.The results of the simulation are analyzed, and the conclusions are as follows:In the fluid temperature field, the highest temperature appears on the wall where the fluid is in contact with the part of gracile axle of the valve core near the valve port. It follows that the cause of the fever is the viscous dissipation of hydraulic oil. Under the condition of the same differential pressure and the same opening, the highest temperature of solid is greater than the highest temperature of fluid, for the heat capacity of solid is less than that of fluid.Compared to two kinds of deformation, it is found that the deformation produced by the heat expansion is greater than that by the fluid pressure. Hence the thermal expansion is the main reason of the deformation in the radius direction of the valve core and the valve sleeve. According to the rule of radial deformation, in some situations, the clearance between the valve core and the valve sleeve changes a lot, which may cause the valve core clamping and paralysis of the system. So we need to avoid these special positions, or to improve the structure of spool valve in order to improve the work performance, which provides reference for the design of the spool valve and has practical significance. |
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