| High speed on-off valve is widely used in automotive shock absorption and fuel injection because of their low cost,simple structure and strong antipollution ability.High speed on-off valve is one of the core components of the hydraulic system,and its performance will directly affect the output accuracy and stability of the hydraulic system,so high speed on-off valve is also the focus of development of the hydraulic system.In order to ensure large flow while having high response performance is the key factor to determine the working performance and application scenarios of high speed on-off valves,and the existing high speed on-off valve structure has a large flow while it is difficult to ensure a faster response speed,at present,the focus of high speed on-off valve research at home and abroad is how to solve or improve the contradiction between large flow and high response,so the research work related to high speed on-off valve large flow and high response performance still has important practical significance.In this thesis,aiming at the problem of improving the contradiction between large flow and high response of high speed on-off valves,a new high speed on-off valve structure combining giant magnetostrictive driver(GMA)and multi-flow surface spool is proposed,and the structural design,flow field characteristics and performance optimization of new high speed on-off valves are studied by theoretical analysis,numerical simulation and multi-objective optimization.The main research work is as follows:(1)According to the requirements of performance indicators,a new high speed onoff valve structure is designed by combining a new stacked giant magnetostrictive driver with a multi-channel flow surface plate spool.The working principle of the overall structure of the high speed on-off valve and the basic characteristics of the valve core are expounded,the calculation formula of the multi-channel flow surface spool is derived,and the flow change law under different inlet and outlet pressure difference and spool opening is analyzed,which provides data support for subsequent analysis.(2)Aiming at the problem of uneven magnetic field of traditional stacked giant magnetostrictive driver,a new GMA stacked sleeve structure is proposed,that is,the top and bottom structure of the sleeve adopts the same material as the magnetic permeability of giant magnetostrictive rod(GMM),while the middle part adopts the design of nonmagnetic conductive stainless steel material.The size of GMM rods is calculated,the finite element models of magnetic field simulation of three different GMA structures are established,and the magnetic field performance of the three GMA structure schemes is compared and analyzed by taking the axial magnetic field strength and uniformity of the GMM rods as the evaluation criteria,and the effectiveness of the designed structures is verified.According to the new GMA structure,the equivalent mathematical model is established,and the numerical simulation method is used to verify the initial value of output displacement,which lays a foundation for the subsequent flow field simulation of high speed on-off valve.(3)A simulation model of the flow field characteristics of a flat spool high speed onoff valve is established,the relationship between grid quality and calculation accuracy is analyzed,the change law of flow,hydraulic power and flow velocity of the spool at different openings is obtained,and the flow value and theoretical calculation are analyzed and verified,and the results are used as data support for subsequent optimization design.The transient flow field flow simulation analysis of the high speed on-off valve was carried out by dynamic grid technology,the dynamic characteristics of the valve core were studied,and the changes of flow,hydraulic power and flow rate during the closing process of the valve core were obtained.(4)Taking the main structural parameters of high speed on-off valve,such as body diameter,seat thickness,seat bore diameter,spool thickness,spool opening diameter and stem diameter,as design variables,and flow and hydraulic power as the optimization objectives,the sensitivity analysis of high speed on-off valves was carried out to obtain the response degree of structural parameters to the optimization objectives.According to the results,three structural parameters,including the diameter of the inner bore of the valve seat,the diameter of the valve core opening and the diameter of the valve body,were determined as the final optimization design variables,and the multi-objective optimization mathematical model of the flow field of the high speed on-off valve was established.By fitting the response surface approximation model instead of the traditional finite element simulation model,the multi-objective optimization model of the flow field is optimized by genetic algorithm.Compared with the initial design,the optimized high speed on-off valve has an 8.72% higher flow rate and 28.01% lower hydraulic power.Finally,the flow field simulation analysis of the high speed on-off valve structure after multi-objective optimization is carried out,and the error analysis is carried out with the response surface results,which verifies the effectiveness of the multi-objective optimization results. |
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