Research On Characteristics Of Key Components And System Of Hydraulic Vibrator

Hydraulic excitation is a technology that combines hydraulic technology and mechanical devices.Compared with traditional mechanical and electric excitation,it has the advantages of stepless amplitude modulation,large excitation force,and high bandwidth.It is the cutting-edge technology of vibration utilization engineering and an indispensable basic technology in the field of reliability testing.It has high engineering application value and broad development prospects.The rotary valve is a key component of the hydraulic vibration exciter,and its valve port flow area has an impact on the waveform characteristics of the excitation system.Its internal flow field changes all the time,which affects the stability and accuracy of the system.Research on the characteristics of the rotary valve and the system,and master the characteristics of the law,which is conducive to improving the performance indicators of the hydraulic exciter,and is conducive to precise control of the system’s excitation characteristics.In this dissertation,a combination of theoretical analysis and simulation is used to study the internal flow field of the rotary valve and the rotary valve-hydraulic cylinder system.Take the vibration excitation system composed of rotary valve and hydraulic cylinder as the research object.Explore the characteristics of the rotary valve and the system in the simulation model under different parameter conditions.The main research work is as follows:(1)The structural features of the main parts of the rotary valve and its working principle are introduced by the dissertation.Different valve port shapes have been designed,and the valve port flow area calculation formulas for these valve port shapes have been derived.The law of the valve port area change is obtained.And the area gradient has different forms of monotonicity and symmetry.(2)The three-dimensional model of the internal flow field of the rotary valve was established through SolidWorks.The grid of the flow field model is divided by ICEM.Dynamic and static flow field simulations are solved by Fluent.The flow field is visualized and processed through Tecplot.The pressure distribution of the flow field inside the rotary valve is revealed.With the increase of the valve port opening,the pressure distribution gradually shows a secondary throttling phenomenon.The maximum flow rate at the valve port decreases with the increase of the valve port opening.When the shape of the valve port is fixed,the jet angle at the valve port is only related to the valve port opening.(3)The hydraulic torque received by the rotary valve is obtained from the Fluent solution.Under dynamic conditions,the spool is affected by the transient hydraulic torque,which is found by comparing the dynamic and static hydraulic torque curves of the oil inlet cavity and the oil return cavity.The direction of steady-state hydraulic power always points to the direction that makes the valve port tend to close.The consistency between the simulation model and the theoretical calculation model is proved by comparing the static simulation hydraulic torque with the theoretical calculation hydraulic torque.(4)The spool groove with arc-shaped diversion has been designed,and its internal flow field has been established as a simulation model.The diversion direction of the arc-shaped groove is the same as the direction of the spool speed.The negative pressure area of the internal flow field of the arc groove valve port is improved to a certain extent,compared with the rectangular valve port.The outlet volume of the valve port of the arc groove is smaller than that of the rectangle,and the flow difference at the maximum valve port opening is 0.546 kg/s.But the export speed is relatively high.The hydraulic torque received by the valve core is smaller than the rectangular valve port during the opening of the valve port,and larger than the rectangular valve port during the closing process of the valve port.The maximum hydraulic torque value during the opening of the valve port is 3.27 N·m,and the maximum value of hydraulic torque when the valve port is closed is 7.93 N·m.(5)The rotary valve-hydraulic cylinder system was modeled and simulated through AMESim.The effects of different load masses,different oil source pressures,different operating frequencies and different valve port shapes on the excitation displacement,excitation force,and excitation speed of the excitation system are revealed.The influence of frequency and load mass on the displacement of excitation is revealed.Under the rotary valve parameters in this article,when the load mass is set to more than 20 kg,the hydraulic cylinder will fail to reset.When the frequency is increased proportionally,the maximum excitation displacement is reduced proportionally.For example,if the frequency is increased by 5 times,the maximum excitation displacement is reduced by 5 times.When designing a vibration exciter,frequency and load quality need to be considered comprehensively.The system vibration waveforms corresponding to different area gradient changes are revealed.In the case of the same peak flow area,the area gradient is a symmetric valve orifice shape system,its vibration waveform amplitude is larger,and the waveform is steeper;The area gradient is a monotonic valve orifice shape system,its vibration waveform amplitude is smaller,and the waveform is flatter.