The Simulation And Analysis Of Internal Flow Pattern In Excavator Multi-way Valve

The integral multi-way valve is widely used in engineering machinery. The integral multi-way valve adopts the method of directly casting channeling, so the internal structure is complex. The valve ports of multi-way valve on the excavator have throttling loss and internal flow resistance loss under any conditions. These two losses in excavator machine occupied large proportion of the energy losses in excavator machine. As is known to all, the fit clearance of multi-way valve is only a few microns and the working environment is atrocious, so there always occur valve sticking resulted from solid particles. Thus the response performance of entire system is influenced. Combined the theoretical analysis and numerical simulation calculation, this study considers the actual working condition of the hydraulic excavator、 various forms of throttling ports and the complex internal flow structure. Aimed at its each individual action and composite action, the flow field and modeling simulation software FLUENT and AMESim software were used. The main parts of flow resistance and the distribution of solid particles and the influence of ring groove were researched thoroughly. The flow passage structure is optimized to reduce the internal resistance loss and the valve sticking problems. This paper can provides a universal reference to optimization design of the internal flow channel of the integral multi-way valve.The main content of this thesis:The background and significance of this thesis is presented. The development of hydraulic system and its key components of engineering machinery is summarized. The current research progress and problems on pressure loss and valve sticking leaded by solid particles are analyzed. The main research subjects are summarized on the basis of software simulation.Combined the variable pump structure principle and pressure-flow characteristic curve, the paper analyzes the negative flow-constant power control system which is based on each individual action and composite action hydraulic excavator. To simulated the valve and system using AMESim, the area-displacement curve of the valve ports at different conditions were leaded into the basic module of slide valve by text form. The analysis of system dynamic characteristics was analyzed based on simulation model. The related pressure and flow numerical result of multi-way valve was obtained. The results provided the reference data to the internal flow resistance calculation.Aimed at the multi-way valve, the oil channel was analyzed and the model of whole flow field in different working conditions was built. The internal flow resistance both each individual action and composite action in excavator was analyzed. The results shows that the flow resistance loss mainly occurred at the place of confluence port, sudden enlargement of inlet port, valve orifice and the corner of flow channel. The inlets of two sides of confluence port are asymmetric. The velocity and flow resistance of the two sides were both different. High-speed convergence of hydraulic oil increases the flow resistance inside the window of the confluence, and that makes the local stress distribution change.Using the model of "Mixture" in software FLUENT. And the solid-liquid two-phase flow in spool valve without ring groove was also simulated. The existing mechanism of ring groove was probed. The mechanism of valve sticking induced by solid particles was discussed.Finally, aim at the part of resistance losses, through the parameterized modeling of the valve body and multiplex simplified flow channel structure optimization design, and then compared the optimized flow of the flow field and optimization numerical. The end, this thesis research work and achievements are summarized and prospects the further research content.