| Domestic and foreign hydraulic shock vibration devices mostly adopt position feedback valve control cylinder structure,hydraulic jet impactor adopts bistable attached wall jet element to directly drive the piston hydraulic cylinder action,under the condition of continuous hydraulic power input to form self-excited oscillation.The above-mentioned hydraulic vibration system using bistable wall-mounted jet elements to directly drive the piston cylinder has simple and easy characteristics in principle and structure,but for large flow conditions,such hydraulic jet impactors will inevitably produce large throttling losses at the nozzle of the jet element,and lead to serious erosion and heating phenomenon,which restricts the development goal of higher efficiency and long life of its products.This paper proposes a combined fluid-controlled hydraulic shock vibration device constructed by using the attached wall bistable jet element as the pilot stage,using it to control the high-frequency switching of the hydraulic directional valve,and then driving the piston or plunger cylinder by the hydraulic directional valve as the main control stage,and using the principle of dynamic pressure feedback.Compared with the hydraulic shock vibration device with position feedback,the hydraulic shock vibration device of combined fluidic control can make full use of the technical advantages of jet elements,effectively avoid the erosion phenomenon caused by high-pressure and large-flow jets,and the dynamic pressure feedback and position feedback hydraulic shock vibration device greatly improve the working performance of high-pressure and large-flow hydraulic shock vibration device,effectively improve the system efficiency,and at the same time make the working parameters of the hydraulic vibration device easy to adjust to meet the requirements of various complex working conditions for product performance.The main work of this thesis is as follows:A miniaturized wall-mounted bistable jet element was designed,and the influence of structural parameters on the characteristics of the jet adhesion was analyzed.Based on MATLAB/Simulink(Simscape),a dynamic simulation model of dynamic pressure feedback combined fluidic hydraulic shock vibration system is established,and the simulation results show that the hydraulic shock vibration system based on the joint control of jet element and valve can realize self-excited vibration controlled by dynamic pressure feedback under the condition of parameter adaptation.On this basis,the effects of the nozzle width of the attached bistable jet element,the displacement of the hydraulic pump powering the wall bistable jet element and the hydraulic pump displacement powering the hydraulic cylinder on the system performance were analyzed,when the displacement of the hydraulic pump powering the pilot system was 36(88)~3/rev,and the displacement of the hydraulic pump powering the working cylinder was 500(88)~3/rev,the reversing time of the hydraulic directional valve was 26.797ms,and the maximum impact end velocity of the hydraulic cylinder piston was 6.817m/s,and the instantaneous efficiency of the system is up to 82.55%.The analysis shows that the stroke pressure of the hydraulic cylinder is lower than the return pressure,and the instantaneous power of the impact mechanism can exceed the power of the pump under the condition of accumulator,and the accumulator will greatly increase the instantaneous power.The dynamic pressure feedback combined fluidic hydraulic shock vibration experimental test device was designed,and the experimental test device was completed.Lay the foundation for further experimental research. |
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