Numerical study on key parameters of a Magnetorheological Fluid reciprocating seal with increasing width of pole teeth and pole piece

2021 ◽  
pp. 1-16
Author(s):  
Xiaolong Yang ◽  
Ying Guan ◽  
You Li ◽  
Shanghan Gao
Keyword(s):  
Permanent Magnet ◽  
Numerical Study ◽  
Magnetorheological Fluid ◽  
Hydraulic Cylinder ◽  
Pole Piece ◽  
Gap Height ◽  
Theoretical Pressure ◽  
The Magnetic Field ◽  
Field Intensity Distribution ◽  
Sealing Gap

In order to solve the problem of reciprocating seal for hydraulic cylinder, a new structure of Magnetorheological fluid (MRF) reciprocating seal with increasing width of pole teeth and pole piece was designed. The theoretical analysis of MRF reciprocating seal is carried out. The magnetic field intensity distribution in the sealing gap of MRF reciprocating seal was analyzed by finite element method. According to the pressure capability formula of MRF, the theoretical pressure capability is calculated. The influences of structure parameters such as the number of magnetic sources, sealing gap height, pole teeth length, the ratio of permanent magnet height to its length, the ratio of pole piece height to shaft radius on the sealing capabilities were studied. The results showed that the pressure capability of MRF reciprocating seal increases with the increase of the number of magnetic sources and with the decrease of the sealing gap height. With the increase of the pole tooth length, the pressure capability of the reciprocating seal increases. With the increase of the ratio of permanent magnet height to its length, the pressure capability of the reciprocating seal increases first and then decreases. With the increase of the ratio of the pole piece height to shaft radius, the pressure capability of the MRF reciprocating seal increases first and then decreases.

Numerical analysis and experimental verification of magnetic fluid sealing for air cylinder in Aerospace Engineering

2021 ◽  
pp. 1-17
Author(s):  
Chen Fan ◽  
Zhang Chongfeng ◽  
Yang Xiaolong
Keyword(s):  
Magnetic Field ◽  
Numerical Analysis ◽  
Service Life ◽  
Permanent Magnet ◽  
Magnetic Fluid ◽  
Slot Width ◽  
Aerospace Engineering ◽  
Pole Piece ◽  
The Magnetic Field ◽  
Sealing Gap

In order to solve the problem of short service life (2 months) and zero leakage of air cylinder in aerospace engineering, this paper innovatively designs a magnetic fluid sealing device of air cylinder in aerospace engineering through magnetic circuit analysis and magnetic fluid sealing theory. The magnetic field finite element method is used to calculate the magnetic field distribution in the sealing gap under different key parameters such as the number of pole teeth, the height of the radial sealing gap, the thickness of the permanent magnet, the slot width, the ratio of pole piece height to shaft. And numerical analysis of the number of pole teeth, the radial sealing gap height, permanent magnet thickness, slot width, the ratio of pole piece height to shaft and other key parameters on the magnetic fluid sealing performance. Finally, the reliability of the reciprocating magnetic fluid sealing withstand voltage is verified by experimental methods. Research indicates. The pressure capabilities of magnetic fluid sealing is increasing with the increase of the number of pole teeth. The pressure capabilities of magnetic fluid sealing is decreasing with the increase of the radial sealing gap. The sealing withstand voltage increases first and then decreases with the increase of the thickness of the permanent magnet, and finally increases, and the value of the withstand voltage is the largest when the thickness of the permanent magnet is 7.8 mm. The sealing pressure capabilities increases as the slot width increases. The sealing withstand voltage increases first and then decreases as the ratio of pole piece height to shaft increases, and when the ratio of pole piece height to shaft is 0.8, the sealing withstand voltage reaches a maximum value. The pressure test finally reaches the pressure value of 6 MPa, which can meet the pressure value demand of medium pressure cylinder, indicating that the magnetic fluid sealing technology can effectively solve the leakage problem existing in the air cylinder technology of Aerospace Engineering, and improve the reliability and service life of the air cylinder.

Design of a safety escape device based on magnetorheological fluid and permanent magnet

2012 ◽  
Vol 24 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Bintang Yang ◽  
Tianxiang Chen ◽  
Guang Meng ◽  
Zhiqiang Feng ◽  
Jie Jiang ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Model ◽  
Magnetic Field Intensity ◽  
Magnetorheological Fluid ◽  
Test Results ◽  
Element Analysis ◽  
Braking Torque ◽  
The Magnetic Field

In this research, a novel safety escape device based on magnetorheological fluid and permanent magnet is designed, manufactured, and tested. The safety escape device with magnetorheological fluid and permanent magnet can provide an increasing braking torque for a falling object by increasing the magnetic field intensity at the magnetorheological fluid. Such increase is realized by mechanically altering the magnetic circuit of the device when the object is falling. As a result, the falling object accelerates first and then decelerates to stop in the end. Finite element analysis is used to determine some of the specifications of the safety escape device for larger braking torque and smaller size. Finite element analysis results are also used for theoretical study and establishment of the dynamic model of the safety escape device. A prototype is realized and tested finally. The experimental test results show that the operation of the prototype conforms to the prediction by the dynamic model and validates the feasible application of magnetorheological fluids in developing falling devices.

Measurement Error of the Coercivity Hcj of NdFeB Permanent Magnet Caused by Air Gap

2013 ◽  
Vol 652-654 ◽  
pp. 607-611
Author(s):  
Wen Huan Xu ◽  
Ai Zhi Sun ◽  
Shen Wu ◽  
Jun Yang ◽  
Chao Zou ◽  
...  
Keyword(s):  
Measurement Error ◽  
Permanent Magnet ◽  
Magnetic Field Intensity ◽  
Air Gap ◽  
Standard Samples ◽  
Measurement Systems ◽  
Intrinsic Coercivity ◽  
Ndfeb Permanent Magnet ◽  
The Magnetic Field ◽  
Field Intensity Distribution

Regular rare earth permanent magnet measurement systems are only able to measure standard samples with a fixed size. But NdFeB materials are usually processed into various kinds of shapes. Bonding magnets are even often formed together with the shaft or other parts. So there will be a distinct error in conventional measurement. The magnetic field intensity distribution between two poles of the system was analyzed. Because of the existence of air gap between the magnet and the poles of the measurement system, the measurement magnetic circuit is open in this experiment. By changing the height of the magnet and air gap, the measurement error of the intrinsic coercivity Hcj of NdFeB magnets is researched under this condition.

Temperature suppression of metal panel in electromagnetic field

Circuit World ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 317-324
Author(s):  
Guochao Zheng ◽  
Fuli Wang ◽  
Baiping Yan ◽  
Runting Cheng
Keyword(s):  
Permanent Magnet ◽  
Magnetic Induction ◽  
Permanent Magnets ◽  
Magnetic Field Intensity ◽  
Metal Plate ◽  
Content Type ◽  
Magnetic Induction Intensity ◽  
Metal Panels ◽  
The Magnetic Field ◽  
Field Intensity Distribution

Purpose The purpose of this study is to suppress the temperature rise of high voltage wall bushing metal plate. Design/methodology/approach First, the authors built a model of a traditional metal plate and got the magnetic field intensity distribution by FEA tools. Optimized according to the magnetic field intensity distribution, the authors slot the traditional metal plate and embed permanent magnets in the slot. Finally, the authors got the temperature distribution diagrams of the above three cases at different current levels by FEA tools. Findings Slotted metal plate is beneficial to suppress magnetic induction intensity, but the improvement of the magnetic induction intensity uniformity is not obvious. The method of embedding a permanent magnet in a slotted metal plate can optimize the magnitude and uniformity of the magnetic induction intensity in the metal plate. The larger the current passing through the metal plate, the better the temperature suppression effect of the slotted metal plate and the slotted metal plate embedded in the permanent magnet. Originality/value The effect of structural factors, slotting plate and setting permanent magnets on slots on the temperature of supporting plate is studied. The paper proposes two methods, slotting metal panels and embedding permanent magnet metal panels, to solve the problems of eddy current loss and high calorific value of the panel, which is of great significance to the safety of the grid equipment.

Numerical Study on Magnetic Field Characteristics of Typical Permanent Magnet

2011 ◽  
Vol 704-705 ◽  
pp. 1073-1078
Author(s):  
Chang Liang Shi ◽  
Yi Shun Zhang ◽  
Hong Guang Jiao
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Permanent Magnet ◽  
Magnetic Field Strength ◽  
Simulation Analysis ◽  
Numerical Study ◽  
Element Model ◽  
Numerical Verification ◽  
Uniformity Coefficient ◽  
The Magnetic Field

Selecting a single piece of typical rectangular open planar magnet，with its axial magnetization, to build a finite element model. Based on ANSYS software, the article used NdFeB45 material properties, giving 100×100×10mm to fit the relationship of three-dimensional size. In the air zone as 10 times as model size, it adopted a static simulation analysis of the effect on relationship between axial magnetic distance and magnetic field strength. The magnetic field contours as simulation results, after the Origin software fitting process, obtained an equation is: ; Comparing with the formula: , which reflected the basic characteristics of permanent magnetic field, and with the numerical results by Jing-tian LI using equivalent magnetic charge method, they all appeared: the magnetic field strength exponentially decrease along with the magnetic distance increases, the magnetic field non-uniformity coefficient is of 4.628% deviation, the fitting correlation coefficient R is 0.99924; As a result of the numerical verification results, it also visually response to the magnetic field parameters of open permanent magnet.

scholarly journals Variable Gap Sealing Technology of a Hydraulic Cylinder Based on Magnetic Shape Memory Alloy

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 950
Author(s):  
Xiaolan Chen ◽  
Fuquan Tu ◽  
Feng Gao ◽  
Heming Cheng ◽  
Shixiong Xing
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Active Role ◽  
Hydraulic Cylinder ◽  
Hydraulic Systems ◽  
Magnetic Shape Memory ◽  
The Impact ◽  
The Magnetic Field ◽  
Sealing Gap

The synergistic control of resistance reduction and sealing poses challenges to enhancing the rapid dynamic response ability of servo hydraulic cylinders; the key to solving this problem is effectively controlling the sealing gap value. In this study, a micro-variation between the hydraulic cylinder and the piston based on the disadvantage of conventional seals, constant gap seals, and lip gap seals was constructed; MSMA assist support blocks were designed on the piston to form a gap seal strip; then, the sealing gap value could be changed by controlling the magnetic field intensity. Simultaneously, the effects of magnetic field strength, parts-manufacturing precision, temperature, and hysteresis on the micro-variation in the MSMA were analyzed, and effective solutions were proposed. Finally, experiments on the magnetic field, temperature, and hysteresis were conducted by the measurement system. The results showed that the variable value of the sealing gap with the MSMA is feasible under ideal conditions, and can effectively change the amount of MSMA expansion by controlling the magnetic field strength, temperature, preload, etc., and then change the amount of the sealing gap of the hydraulic cylinder. This is the key to achieving friction and sealing control, which plays a crucial and active role in improving the efficiency of hydraulic systems. However, the impact of hysteresis effects cannot be ignored, which will be the main problem to be solved in the future.

Viscosity Control of Magnetorheological Fluid by Power Saving Magnetizing Mechanism Using Movement of Permanent Magnet

2020 ◽  
Vol 32 (5) ◽  
pp. 977-983
Author(s):  
Jumpei Kawasaki ◽  
Yuki Nakamura ◽  
Yasukazu Sato ◽  
◽  
Keyword(s):  
Magnetic Field ◽  
Power Consumption ◽  
Permanent Magnet ◽  
Electric Power ◽  
Field Intensity ◽  
Magnetic Field Intensity ◽  
Magnetic Circuit ◽  
Angular Position ◽  
Magnetorheological Fluid ◽  
The Magnetic Field

Generally, the magnetic field applied to a magnetorheological fluid (MRF) is generated by electromagnets. Electromagnets consume electric power during MRF magnetization, which is an issue. In this study, we examine two kinds of magnetizing mechanism using a permanent magnet, instead of electromagnets, to save electric power and generate a magnetic field on the MRF. One mechanism linearly moves the permanent magnet into the magnetic circuit composed of yokes. The magnetic field intensity on the MRF is then controlled by changing the overlap between the magnet and the yokes. The other mechanism rotates a permanent magnet in the magnetic circuit. The magnetic field intensity on the MRF is then controlled by changing the relative angular position between the magnet and the yokes. These two mechanisms normally generate force or torque on the magnet toward a magnetically stable position concerning the magnet, and the force or torque causes power consumption to hold and move the magnet. We design herein special magnetic circuits and a cancelation mechanism for the force or torque that drastically reduce the power consumption during the MRF magnetization compared with an electromagnet-type magnetizing device.

scholarly journals Numerical Study of Buoyancy Convection of Air under Permanent Magnetic Field and Comparison with That under Gravity Field

2014 ◽  
Vol 2014 ◽  
pp. 1-13
Author(s):  
Kewei Song ◽  
Wenkai Li ◽  
Yang Zhou ◽  
Yuanru Lu
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Permanent Magnet ◽  
Gravity Field ◽  
Numerical Study ◽  
Magnetic Flux Density ◽  
Square Enclosure ◽  
Buoyancy Convection ◽  
The Magnetic Field ◽  
Local Value

Magnetothermal free convection of air in a square enclosure under a nonuniform magnetic field provided by a permanent neodymium-iron-boron magnet is numerically studied. The natural convection under the gravity field alone is also studied for comparison. The physical fields of magnetizing force, velocity, and temperature as well as the local distribution characteristic of Nusselt number are all presented in this paper. The results show that the buoyancy convection of air in the square enclosure under magnetic field is quite different from that under the gravity field. The local value of Nusselt number under the magnetic field supplied by a permanent magnet with a residual magnetic flux density of about 4.5 Tesla can reach a high value of about three times larger than the maximum local value of Nusselt number under the gravity field. Relatively uniform distributions of temperature gradient and Nusselt number can be obtained along the cold wall of the enclosure under the magnetic field. A permanent magnet with high magnetic energy product withBrreaching to 3.5 Tesla can play a comparative role on the averaged Nusselt number compared with that under the gravity environment.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

A Mechanistic Model of Material Removal in Magnetorheological Finishing (MRF)

2007 ◽  
Vol 359-360 ◽  
pp. 384-388
Author(s):  
Feng Jun Chen ◽  
Shao Hui Yin ◽  
Jian Wu Yu ◽  
Hitoshi Ohmori ◽  
Wei Min Lin ◽  
...  
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Reynolds Equation ◽  
Removal Rate ◽  
Mechanistic Model ◽  
Magnetorheological Fluid ◽  
Magnetorheological Finishing ◽  
Material Removal Model ◽  
Removal Model ◽  
The Magnetic Field

According to the sharp rheological characteristics of magnetorheological fluid in the magnetic field, the principle and mechanism of magnetorheological finishing is analyzed. Based on the Preston equation, the Reynolds equation and its boundary conditions, the two-dimensional material removal model is built and simulated. Furthermore, a series of MRF experiments are carried out, and the influence of the immersed depth and material kinds on material removal rate are clarified respectively. The experimental results are compared with the modeling results of material removal rate to confirm the mechanistic model validity.

Sign in / Sign up

Export Citation Format

Share Document