Research And Design Of Permanent Magnetic-rheological Fluid And Friction Composite Soft-landing Device

The traditional magneto-rheological brake uses the coil as the magnetic source to produce the magnetic field to excite the magneto rheological effect so as to achieve the braking effect.By special factors,such as power and high temperature,the braking efficiency will be reduced or even failure.In this paper,a permanent magnetic brake is designed,which uses permanent magnet as the magnetic source to produce the magnetic field to excite the magneto rheological effect.In falling process,with the working cavity along the axial direction length and the working chamber of the magnetic field change,the braking torque of MRF has gradually increased to ease the rigid impact landing,and achieve soft landing.At the same time,the friction brake is introduced to adjust the extension of the spring to change the distance between the friction discs,and the height of the object can be adjusted.Base on the composition and characteristics of the rheological properties and MRF,the composition and characteristics of MRF are studied,and compared with the traditional electromagnetic type of magneto-rheological device has advantages,such as no power loss.In this paper,the three components of the intelligent material of MRF are studied,and the transmission mechanism of MR fluid and the principle of magneto-rheological effect are established.Based on the analysis of three different working modes of MR fluid,the structure of the permanent magnetic cylinder brake is studied,and the mathematical model is established.According to the design requirements of the permanent magnet as the magnetic source and the adjustable braking distance,the reasonable mechanical structure and magnetic circuit structure are designed.Using ANSYS to simulate the model,the results show that: in the range of error,the design parameters and the magnetic field design is reasonable.Furthermore,the possible factors affecting the magnetic field of the device,such as the pole spacing,the magnetic pole angle and the thickness of the working chamber,are analyzed.The MRF torque analysis results show that due to the effect of objects fall height,the MRF is changed and the braking torque increases,and the object first accelerates,then decelerates and final rest.There is No rigid impact,the soft landing design is reasonable.Through the simulation analysis,the conclusion is reached that the height of the object can be adjusted by changing the spring elongation and adjusting the distance between the friction discs.Based on the existing experimental conditions,the performance of the brake is tested.The experimental results show that the experimental values are in agreement with the theoretical values.With the falling of the object,the working magnetic field of magneto rheological fluid is changing,and the braking torque is gradually increasing.At the same time,the height of the spring is affected by the elongation of the spring.The subject has been authorized by the national invention patent,and the research results are published in the CSCD journal,which has a certain reference value for the design of the permanent magnetic rheological device.