The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo val...The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo valve would reach 120℃ and the valve core and valve sleeve deform in a short amount of time. So the control precision of servo valve significantly decreases and the clamping stagnation phenomenon of valve core appears. In order to solve the problem of degraded control accuracy and clamping stagnation of servo valve under large temperature difference circumstance, the numerical simulation of heat-fluid-solid coupling by using finite element method is done. The simulation result shows that zero position leakage of servo valve is basically impacted by oil temperature and change of fit clearance. The clamping stagnation is caused by warpage-deformation and fit clearance reduction of the valve core and valve sleeve. The distribution roles of the temperature and thermal-deformation of shell, valve core and valve sleeve and the pressure, velocity and temperature field of flow channel are also analyzed. Zero position leakage and electromagnet＇s current when valve core moves in full-stroke are tested using Electro-hydraulic Servo-valve Characteristic Test-bed of an aerospace sciences and technology corporation. The experimental results show that the change law of experimental current at different oil temperatures is roughly identical to simulation current. The current curve of the electromagnet is smooth when oil temperature is below 80℃, but the amplitude of current significantly increases and the hairy appears when oil temperature is above 80℃. The current becomes smooth again after the warped valve core and valve sleeve are reground. It indicates that clamping stagnation is caused by warpage-deformation and fit clearance reduction of valve core and valve sleeve. This paper simulates and tests the heat-fluid-solid coupling of double flapper-nozzle servo valve, and the obtained results provide the reference value for the design of double flapper-nozzle force feedback servo valve.展开更多
Nowadays,more and more attention has been paid to improve the performance of the nozzle flapper servo valve.As a core part of nozzle flapper servo valve,the armature assembly is affected by electromagnetic force,jet f...Nowadays,more and more attention has been paid to improve the performance of the nozzle flapper servo valve.As a core part of nozzle flapper servo valve,the armature assembly is affected by electromagnetic force,jet force and feedback force at the same time.Due to the complex structure of the pilot stage flow field and the high jet pressure,the prediction of the jet force has always been difficult in modeling the transient motion of the servo valve.Whereupon,a numerical simulation method based on the flow-solid interaction(FSI)is applied to observe the variation of the jet force when the flapper is moving.Different parameters are employed to seek a suitable numerical simulation model which can balance the accuracy and computational cost.By comparing with the experiment results,the effectiveness of numerical simulation method in predicting the variation of the jet force and cavitation is verified.By this numerical simulation model,the distribution of flow field and the force on the flapper predicted by the moving and fixed flapper are compared.The results show that more dynamic details are achieved by the transient simulation.By analyzing the numerical simulation results of different inlet pressures and flapper vibration frequencies,the relationship between the movement of the flapper,the flow field distribution,the jet force and the inlet pressure is established,which provides a theoretical basis for the subsequent modeling of the armature assembly.展开更多
A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezo...A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezoelectric bimorph and beryllium-bronze materials.The structure and working principle of the new type nozzle flapper amplifier are introduced.Pressure characteristic and flowrate characteristic are analyzed by experimental method.The research results show that pressure characteristic has large amplification factor and output pressure;flowrate characteristic has large linear range and output flowrate.展开更多
In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from non...In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventhorder model are derived in terms of servo valve physical parameters and fluid properties explicitly.For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.展开更多
基金Supposed by National Natural Science Foundation of China(Grant No.51075348)Hebei Provincial Natural Science Foundation of China(Grant No.E2011203151)Research Fund for Doctoral Program of Higher Education of China(Grant No.20101333110002)
文摘The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo valve would reach 120℃ and the valve core and valve sleeve deform in a short amount of time. So the control precision of servo valve significantly decreases and the clamping stagnation phenomenon of valve core appears. In order to solve the problem of degraded control accuracy and clamping stagnation of servo valve under large temperature difference circumstance, the numerical simulation of heat-fluid-solid coupling by using finite element method is done. The simulation result shows that zero position leakage of servo valve is basically impacted by oil temperature and change of fit clearance. The clamping stagnation is caused by warpage-deformation and fit clearance reduction of the valve core and valve sleeve. The distribution roles of the temperature and thermal-deformation of shell, valve core and valve sleeve and the pressure, velocity and temperature field of flow channel are also analyzed. Zero position leakage and electromagnet＇s current when valve core moves in full-stroke are tested using Electro-hydraulic Servo-valve Characteristic Test-bed of an aerospace sciences and technology corporation. The experimental results show that the change law of experimental current at different oil temperatures is roughly identical to simulation current. The current curve of the electromagnet is smooth when oil temperature is below 80℃, but the amplitude of current significantly increases and the hairy appears when oil temperature is above 80℃. The current becomes smooth again after the warped valve core and valve sleeve are reground. It indicates that clamping stagnation is caused by warpage-deformation and fit clearance reduction of valve core and valve sleeve. This paper simulates and tests the heat-fluid-solid coupling of double flapper-nozzle servo valve, and the obtained results provide the reference value for the design of double flapper-nozzle force feedback servo valve.
基金Supported by the National Natural Science Foundation of China(51675119)。
文摘Nowadays,more and more attention has been paid to improve the performance of the nozzle flapper servo valve.As a core part of nozzle flapper servo valve,the armature assembly is affected by electromagnetic force,jet force and feedback force at the same time.Due to the complex structure of the pilot stage flow field and the high jet pressure,the prediction of the jet force has always been difficult in modeling the transient motion of the servo valve.Whereupon,a numerical simulation method based on the flow-solid interaction(FSI)is applied to observe the variation of the jet force when the flapper is moving.Different parameters are employed to seek a suitable numerical simulation model which can balance the accuracy and computational cost.By comparing with the experiment results,the effectiveness of numerical simulation method in predicting the variation of the jet force and cavitation is verified.By this numerical simulation model,the distribution of flow field and the force on the flapper predicted by the moving and fixed flapper are compared.The results show that more dynamic details are achieved by the transient simulation.By analyzing the numerical simulation results of different inlet pressures and flapper vibration frequencies,the relationship between the movement of the flapper,the flow field distribution,the jet force and the inlet pressure is established,which provides a theoretical basis for the subsequent modeling of the armature assembly.
基金Item Sponsored by National Natural Science Foundation of China[51105170]Program of Science and Technology Development Plan of Jilin province of China[201105015]
文摘A new type nozzle flapper amplifier for double nozzle flapper electro-hydraulic servo valve is proposed in the paper.The electro-mechanical converter of new type nozzle flapper amplifier is designed by using the piezoelectric bimorph and beryllium-bronze materials.The structure and working principle of the new type nozzle flapper amplifier are introduced.Pressure characteristic and flowrate characteristic are analyzed by experimental method.The research results show that pressure characteristic has large amplification factor and output pressure;flowrate characteristic has large linear range and output flowrate.
基金the National Natural Science Foundation of China (No. 50975055) for financial support
文摘In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventhorder model are derived in terms of servo valve physical parameters and fluid properties explicitly.For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.
