Researches Of Theory And Design Method On The High Pressure And High Water-based Hydraulic Valve

The powered support of fully mechanized coal face is a kind of complicated coal mine machinery, which can sustain and control the roof of working face reliably and efficiently, guaranteeing coal miner's safety and the operation of normal tasks. The electro-hydraulic controlled powered support is one of the important signs in the currently advanced excavate coal equipment. High pressure and high water-based (HPHWB) solenoid pilot valve is the key component of the electro-hydraulic control system which has complex structure and high precision. At present it was researched and manufactured only in some countries like Germany and America. It belongs to a difficult technology. Our country ever made an attempt to design and manufacture the hydraulic valve independently, but failed, because it needs further research on the key technology of HPHWB hydraulic valve based on the synthesis means of multidiscipline theory and modern digital technique, except the experience and old data. Thereby, HPHWB solenoid pilot valve still depends on import in our country, which becomes one of the pivotal technologies that restrict domestic development in coal mining technique from mechanization to automation.The thesis first discusses the key technology problem of erosion wear and sealing leakage mechanism for HPHWB hydraulic valve; then applies the result-to the theory analysis and structural design of solenoid pilot valve, thus combining the basic research with practical application and offering a theoretical support for development pilot valve. Based on computational fluid dynamics (CFD), fractal theory and multi-rigid-body system dynamics theory and so on, the author establish flow field simulation model, leakage mechanism model, dynamics simulation model and system simulation model of hydraulic valve by combining means of theory, simulation and examination, and then make analysis of numerical calculation. Credible theory basis is offered for the hydraulic valve design.Wall faces abrasion of HPHWB hydraulic valve affect strongly the operation life of hydraulic valve. The author researches erosion wear mechanism of hydraulic valve under the high velocity and high pressure condition by combining technology of CFD and erosion theory, and establishes erosive mathematical model of HPHWB hydraulic valve. By visual simulation, erosion wear distribution of coal particles eroding plain valve and ball valve are predicted; accurately indicate the influencing position and degree of key components eroded. Moreover, the author research interactive breakage of fretting wear and erosion wear between valve core and pole. A means for avoiding wear superposition is suggested by changing the center pole structure to sidepiece pole structure. In addition, the author makes experimental investigation to several kind nonmetals, and offer basis for optimum seeking of sealing material of HPHWB hydraulic valve.Using modern digital technique, the author carries on cavitation study of high water-based medium hydraulic valve to solve the problem difficult to research by experiment. By using cavitation mathematical model of high water-based hydraulic valve, cavitation form of low pressure sealing will be researched, and the positions that produce cavitations will be easily found. Analyses show that low-pressure zone corresponds with the cavitation zone of high vapor volume fraction, and sidepiece pole structure can likewise reduce cavitation.The foundation of fractal geometric provides new theory and means for the research on complex and ruleless phenomenon. On the basis of surface appearance changing, the author puts forward train of thoughts of microscopic seal mechanism for HPHWB hydraulic valve, and analyzes microscopic contact mechanism of wave trough and elastic point contact area of rough surface. Then the author derive the calculating formulas of leakage rate and surface roughness, fractal parameter, sealing contact pressure based on aperture current N-S equation, establishes leakage model of fractal parameters, and discuss the relations of fractal parameter, seal force and leakage rate by numerical simulation. Results show controlling surface appearance parameters are able to availably reduce leakage rate of hydraulic valve. Besides, after experiment studying the relation of leakage rate between different surface roughness, seal contact pressure, and the seal width, the author comes to the quantitative conclusion that is meaningful to engineering application.As to peculiar request of the electro-hydraulic controlled powered support, the author uses the solenoid structure design electromagnet that adapt to pilot valve in the powered support. Flux density and flux lines contour are simulated, and the key structure parameters of electromagnet are optimized to make sure that the electromagnet response speed is rapid and operating smooth is reliable. Results show that the highest place of flux density is superposition of armature and guide sleeve end of pole piece, and the changing for pole piece inside diameter unilateral gap settle on the thrust characteristic. Finally, experiment confirms the validity of numerical analysis.When the movement property of solenoid pilot valve is studied, virtual prototype technology contributes to a forward-looking decision. In order to evaluate dynamic characteristics of pilot valve, the author introduced displacement response curve to measure its dynamic performance. Numerical computational results are obtained by solving the dynamic mathematic model of pilot valve. The author make three-dimensional solid model based on considering synthetically contact and topological relation of pilot valve interior movement components, and study the changes of damping coefficient, mass and stiffness to dynamic characteristics effect of pilot valve, predict accurately its dynamic performance under the real operating condition. Geometric parameters are repeatedly modified in accordance with preconcerted system performance and prospective target; finally achieve perfect dynamic response performance. A new thought is opened up for pilot valve design.Pressure change in the operating orifice of solenoid pilot valve will cause its internal change in flow field, while outlet pressure change of pilot valve is affected by hydraulic-controlled main valve and leg and so on. Therefore, the author conduct a research on dynamic response of pilot valve from view of system, establishes simulation model of electro-hydraulic controlled system based on AMESim, and obtain different flow-pressure characteristic curve of operating orifice of pilot valve, and then offer basis for initial boundary set of flow field simulation of pilot valve. Flow field distribution of pilot valve are studied on the basis of the above conclusion; and reasonable structure of HPHWB pilot valve is established according to varying relations that pressure loss and velocity distribution change with flow rate, outlet pressure and inlet position of pilot valve.Studies program of the paper involved multidisciplines theory and modern experiment technology, which predominant idea is overlapping and fusion of multidisciplines under innovative system. Based on the approach, the author research on theory problem and design method of high pressure and high water-based hydraulic valve, and resolve the practical problem.