Research On Vibration Characteristics And Test Method Of Conical Pressure Reducing Valve

The hydraulic cone valve is widely used in various hydraulic systems because of its simple structure,good sealing performance and strong flow capacity.However,the stability of the quality system of “valve core spring” is poor,which will cause the pressure fluctuation of the hydraulic system.When the hydraulic system is disturbed,the valve core deviates from the balance state and enters into the unstable state,causing the vibration of the cone valve.The vibration of the cone valve affects the control accuracy and stability of the hydraulic system.In recent years,with the high-pressure,high-speed and high-power of hydraulic technology,engineering application puts forward more stringent requirements on the performance of the cone valve,so the research on the vibration characteristics of the cone valve is of great practical significance.In this paper,theoretical analysis and experimental analysis are used to study the vibration characteristics of the conical valve.In this paper,the vibration characteristics of conical valve core are studied theoretically,and the transfer function of conical valve core vibration is obtained.In addition,the whole experimental system used in this paper is built,including the hydraulic system,image information acquisition system,vibration signal acquisition system and synchronous measurement system,which provides the theoretical support and experimental equipment foundation for the following vibration analysis of conical pressure reducing valve spool.Aiming at the series of valve core vibration images taken by high-speed camera,the calibration and coordinate system are established.Through image filtering,image sharpening,binarization and edge detection,the contour of valve core is extracted.Through corner detection and least square fitting,the curve of valve core vibration is obtained in batch.It is found that the curve of valve core obtained by least square method has better accuracy,The signal-to-noise ratio is higher.It is also found that there is a certain delay between the vibration displacement of the valve core and the pressure fluctuation at the inlet,and the main frequency of the vibration curve signal of the valve core is obtained through FFT.According to the parameters of inlet pressure,spring preload,spring stiffness and valve core cone angle,the influence of control variable method on the valve core vibration characteristics of conical relief valve is studied.The results show that with the increase of the inlet pressure of the experimental valve,the value of the balance position of the valve core vibration increases,the amplitude of the valve core becomes larger,the amplitude of the main frequency of the valve core vibration increases first and then decreases,and the energy proportion of the main frequency in the power spectrum decreases gradually;the influence of the inlet pressure is inversely proportional to the influence of the spring pre compression,only the amplitude of the main frequency decreases;with the spring pre compression With the increase of stiffness,the value of balance position of valve core vibration decreases.The amplitude of valve core decreases first and then increases.The main frequency of 220 Hz of valve core vibration increases first and then decreases in the power spectrum.With the increase of half cone angle of experimental valve core,the value of balance position of valve core vibration decreases,but the growth rate of its decrease decreases gradually.The amplitude of valve core decreases first and then increases In the big trend,when the half cone angle of the valve core is 30°,its working state is the most stable;the amplitude of the main frequency of the valve core vibration decreases first and then increases;the proportion of the main frequency of the valve core vibration 220 Hz in the power spectrum decreases gradually.The thesis has 52 figures,4 tables and 89 references.