| The magnetic liquid is composed of three substances:a surfactant,a base carrier liquid and magnetic particles.It is a flowable ferromagnetic stable colloidal solution.In order to improve the linearity,sensitivity,resolution,hysteresis and repeatability of the sensor,this new type of functional material can be applied to the sensor.In this paper,the magnetic liquid based on oil is used as a new functional material,and the change of magnetic field can be detected by Hall element by using the characteristic of floating permanent magnet larger than its own density.A new Hall type magnetic liquid micro-pressure difference sensor is proposed.In theory,the magnetic field distribution of the cylindrical permanent magnet on the moving part of the sensor model is first deduced,and the formula of the magnetic field force of the cylindrical permanent magnet and the circular permanent magnet is deduced,as well as the static characteristics of the magnetic liquid micro-pressure difference sensor are analyzed.Indicators.For numerical simulation,using MAXWELL finite element analysis software,the magnetic field distribution on the axis between the two cylindrical permanent magnets on the moving part was simulated firstly,and the appropriate length of the permanent magnet bracket was analyzed and selected;then the magnetic field force between the permanent magnet and the circular permanent magnet is analyzed and calculated to obtain the theoretical model of the magnetic field force within the corresponding movement range of the moving part.Finally,the entire magnetic liquid micro-pressure sensor is modeled,and the magnetic field variation curve between the gap between the whole moving part and the inner diameter of the transparent glass tube is analyzed,and the theoretical maximum voltage value of the sensor is calculated.In terms of experiments,the magnetic liquid micro-pressure sensor is processed and an experimental platform is built.Firstly,the magnetic field force between the cylindrical permanent magnet and the circular permanent magnet is collected and analyzed,and then a series of input and output experiments are carried out on the magnetic liquid micro pressure difference sensor.The following conclusions can be obtained:(1)Compared with the inductance coil,the Hall element,as the detection element of the magnetic liquid micro-pressure sensor,has the characteristics of small volume and high linearity.(2)Two cylindrical permanent magnets of the same polarity have linear magnetic field intensity on their axis within a certain range.The length of the bracket is selected L=10 mm,the magnetic field at the detection position of the Hall element can be guaranteed,and the magnetic field changes as linearly as possible in the movable range of the moving part.(3)Through data simulation and experimental results,it can be analyzed that the static characteristics of the sensor are optimal when the length of the permanent magnet holder in the magnetic liquid micro-pressure difference sensor is mm,and the initial spacing of the moving parts is0D=29 mm.(4)The magnetic liquid micro-pressure sensor designed in this paper has a range of±1000Pa,accuracy is ?Xma x=10 mm,linearity is ?L=5.03%,sensitivity is K=1.46 m V/Pa,resolution is 0.34%F.S.,hysteresis is ?H=0.82%,repeatability is ?R=±1.91%.It can meet the precision measurement of micro pressure difference in the industrial field. |
PDF Full Text Request