Analytical Modelling and Experiment of Novel Rotary Electro-Mechanical Converter with Negative Feedback Mechanism for 2D Valve

The manufacturing of spiral groove structure of two-dimensional valve(2D valve)feedback mechanism has shortcomings of both high cost and time-consuming.This paper presents a novel configuration of rotary electro-mechanical converter with negative feedback mechanism(REMC-NFM)in order to replace the feedback mechanism of spiral groove and thus reduce cost of valve manufacturing.In order to rapidly and quantitative evaluate the driving and feedback performance of the REMC-NFM,an analytical model taking leakage flux,edge effect and permeability nonlinearity into account is formulated based on the equivalent magnetic circuit approach.Then the model is properly simplified in order to obtain the optimal pitch angle.FEM simulation is used to study the influence of crucial parameters on the performance of REMC-NFM.A prototype of REMC-NFM is designed and machined,and an exclusive experimental platform is built.The torque-angle characteristics,torque-displacement characteristics,and magnetic flux density in the working air gap with different excitation currents are measured.The experimental results are in good agreement with the analytical and FEM simulated results,which verifies the correctness of the analytical model.For torque-angle characteristics,the overall torque increases with both current and rotation angle,which reaches about 0.48 N·m with 1.5 A and 1.5°.While for torque-displacement characteristics,the overall torque increases with current yet decrease with armature displacement due to the negative feedback mechanism,which is about 0.16 N·m with 1.5 A and 0.8 mm.Besides,experimental results of conventional torque motor are compared with counterparts of REMC-NFM in order to validate the simplified model.The research indicates that the REMC-NFM can be potentially used as the electro-mechanical converter for 2D valves in civil servo areas.

Output Waveform Analysis of an Electro-hydraulic Vibrator Controlled by the Multiple Valves

The existing research of the electro-hydraulic vibrator mainly focuses on system stability, working frequency width and output waveform distortion. However, this high frequency performance of the electro-hydraulic vibrator is difficult to be improved greatly due to fast insufficiently frequency response of the servo valve itself and limited compensation capability of the control structure in the vibrator system. In this paper, to realize high frequency vibration, an improved two-dimensional valve （here within defined as a 2D valve） as a main control component is adopted to the parallel connection with a servo valve to control the electro-hydraulic vibrator, Because the output waveforms of this electro-hydraulic vibrator are incapable to be verified through timely feedback as in the conventional electro-hydraulic servo system, the analysis to the output waveform becomes crucial to the design and control of the electro-hydraulic vibrator. The mathematical models of hydraulic actuation mechanism and the orifice area of the parallel valves connection are established first. And then the vibration process is divided into two sections in terms of the direction of the flow, the analytical expression of the excited waveform is solved. Based on relationships exist between working states and the control parameters the analytical results, the vibration boundary positions and the are derived. Finally an experimental system was built to validate the theoretical analysis. It is verified that this electro-hydraulic vibration system could achieve high working frequency, up to 2 000 Hz. The excited waveform is similar to the sinnsoidal waveform. And the ascent and decent slopes of the waveforms are somewhat asymmetrical. This asymmetry is not only caused by the change of the direction of the elastic force but also dependent on the bias position of the vibration. Consequentky the distortion of effective working waveform is less tha~ 10%. This electro-hydraulic vibrator controlled by the multiple valves could not only greatly enhance the working frequency but also precisely control the vibration characteristic variables such as waveform shape.

Theoretical and experimental investigation on novel 2D maglev servo proportional valve

This paper presents a novel two-dimensional maglev servo proportional cartridge valve(2 D maglev valve),where a contactless maglev coupling is introduced between electro-mechanical converter and valve body to realize functions of force transmission,spool position feedback and linear-rotary motion conversion.Such configuration can effectively reduce cost of both valve manufacturing and electro-mechanical converter,while still maintain features of 2 D valve such as null pilot leakage,high power-to-weight ratio and excellent anti-pollution capacity.Firstly,the characteristic equation of the valve is derived using linear theory,and the stability criterion is established for parameter determination.The influences of crucial structural parameters such as initial height of overlapping area,width of high-pressure and low-pressure holes,acting radius of magnetic force,pitch angle of maglev coupling,length of sensitive chamber and system pressure on the dynamic response are investigated based on AMESim numerical simulation.The prototype valve is then designed and manufactured and a special test rig is built.The no-load flow characteristic,load flow characteristic,leakage characteristic,amplitude and phase frequency characteristics and step response under different system pressures are measured.The experimental results are in a good agreement with the simulated analysis.As an over-damped system,the prototype valve has excellent working stability,which can reach a no-load flow rate of 105.9 L/min with hysteresis of 3.51%,amplitude bandwidth of 28.7 Hz and phase bandwidth of 42.8 Hz under 21 MPa.The research indicates that the 2 D maglev valve can be a potential solution of flow rate control valve for flight control surface system of civil aircraft with high pressure and large flow rate application.