The Research Of The Pilot Type Zero Steady-state Error Of Water Hydraulic Overflow Valve

Hydrostatic transmission, which has the hydraulic pressure controlling valve as the important component, has become an important research direction of fluid power transmission and control with its advantage of no pollution, flame retardancy, good economity, extensive sources. Traditional pressure controlling valve is the steady-state error valve, having a low accuracy of constant pressure. In addition, hydraulic transmission defects with large leakage, poor lubrication, easy corrosion and so on. Therefore, the research on how to improve the performance of hydraulic pressure valve has an important theoretical and practical engineering value.The development of hydraulic transmission, the advantages and disadvantages and the research status in China and abroad are introduced in the paper. And also, the research, in view of pilot type overflow valve, focuses on the reasons of steady-state error in theory, and analyzes that the main reason is that the import pressure changes with the flow; Besides, the paper also establishes the mathe-matical model, derives the flow and pressure difference formula, proposes design-requirements of pilot type zero steady-state error of water hydraulic overflow valve,and steady-state error δ≤0.2%.This paper study on its cavitation and noise problem, design a new structure of pilot type zero steady-state error of water hydraulic overflow valve based on the special physicochemical properties; detecting the inlet pressure of the main valve with the help of the micro-pressure sensor and using closed-loop feedback control and dynamic pressure feedback control to eliminate steady-state error, establishes the flow field of pilot valve and main valve in the CFD model; using the software of Fluent for simlation.verifies the rationality of the design of the main valve; introduces the advantages and disadvantages of giant magnetostrictive material and its working principle, designs a suitable driving for the motion of pilot valve, the intelligent driver—Giant Magnetostrictive Actuator(GMA), establishes of its mathematical model to study on the static and dynamic characteristics, and establishes the mathe-matical model of pilot type zero steady-state error of water hydraulic overflow valve to study on the static, dynamic and stability characteristics.Through the calculation and simulation analysis, we meet the design requirement because the steady-state error of the designed pilot type zero steady-state error water hydraulic overflow valve is δ=0.16%; The CFD analysis of flow field verifies that the structure rationality of the design of zero steady-state error water hydraulic overflow valve can efficiently prevent the generation of cavitation and noise; the responsing speed of GMA is very fast that its maximum output displacement is0.6mm, which meets the requirements of maximum output displacement of the pilot valve core; the zero steady-state error water hydraulic overflow valve has good controlling characteristics, stabilizing pressure characteristics, high bandwidth with the amplitude bandwidth86Hz and phase bandwidth87.6Hz, good stability,achieving stability after12ms.