Magnetorheological Transmission Research Articles

Analysis of electrothermal shape memory alloy and disc-type magnetorheological fluid combined transmission

In this article, a disc-type magnetorheological fluid and electrothermal shape memory alloy spring-loaded slider friction combined transmission device is proposed. A heating model of the electrothermal shape memory alloy spring is used to calculate the relationship between current and spring temperature. Experiments are used to investigate the link between spring temperature and restoring force, as well as magnetorheological fluid temperature, magnetic flux density, and shear yield stress. The torque characteristics of the combined device were evaluated utilizing the coupled magnetic field and thermal field finite element method for the characteristics of the two materials. The results showed that the magnetorheological fluid showed an approximately linear decrease in shear yield stress at high temperatures, up to 37.94 %. The heating rate of the electrothermal shape memory alloy spring was influenced by the surrounding temperature, and the heating rate was too fast to easily cause the time lag of the martensite phase transformation, resulting in the spring restoring force becoming smaller, and its restoring force shows a non-linear increase when the temperature rises from 22 °C to 100 °C. By applying the two materials together, the torque of the combined transmission has been significantly increased, by 91.58 % compared to the same size magnetorheological transmission.

Research on Magnetic Field Characteristics of Counter-roller Magnetorheological Transmission Device Under Different Coil Arrangements

Research on Magnetic Field Characteristics of Counter-roller Magnetorheological Transmission Device Under Different Coil Arrangements

Analysis and experimentation of variable gap magnetorheological transmission device driven by electromagnetic force

To solve the problems of poor transmission performance and small torque regulation range of traditional MR device, a variable working gap MRF transmission device driven by electromagnetic force is proposed. The device uses electromagnetic force driving the squeeze disk to move axially to squeeze the MRF, thereby changing the number of working gaps and effective working thickness of the MRF to improve the transmission performance of the MR device. Based on the coil magnetization effect, the relationship between current, magnetic field intensity, and electromagnetic force is established. According to the driving characteristics of electromagnetic force and the rheological characteristics of MRF, a nonlinear function relationship between electromagnetic force and MRF working gap thickness and working volume is derived. Using the finite element method, a theoretical analysis of the magnetic circuit design, magnetic field distribution and temperature change profile in different parts of MRF device with different currents was conducted, the MRF torque transfer equations were deduced and calculated, and experimentally verified the correctness of the theoretical equations. Finally, the transmission performance of the variable working gap MRF transmission device is tested through the established testing system. Results show that, the required squeeze force is 6.65 kN when the MRF thickness reaches 1 mm in both working gaps. As the current increases from 0.5 to 3.0 A, the electromagnetic force increases from 0.65 to 6.77 kN, with an increase of 972.3%, the average temperature of the MRF in working gap I increases from 25.2°C to 71.2°C and the MRF in working gap II increases from 23.5°C to 48.3°C. When the current is 1.5 A, the MRF in the working gap I reaches magnetic saturation, continue to increase the current to 3.0 A, the MRF thickness in both working gaps is 1 mm, and the MR device transmits torque reach 376.6 N·m, which is 72.3% higher than that of the traditional MR device.

Structural design and performance study of permanent magnet safety coupling based on magnetorheological transmission technology

Based on magnetorheological transmission technology, a design for a permanent magnet safety coupling is proposed. Firstly, the structure scheme of the coupling is designed in detail, and its working principle and process are explained; Additionally, the influence of coupling structural parameters on magnetic field strength is studied by ANSYS, and the coupling’s structural parameters are optimized; Finally, the prototype of the permanent magnet magnetorheological fluid coupling is tested for no-load characteristics and torque regulation characteristics through the preparation of magnetorheological fluid (MRF) and the construction of an experimental platform, the experimental results demonstrated that the prototype effectively transmits torque, and the no-load torque increases as the speed increases, at a motor speed of 400 r/min, the experimental prototype achieves a maximum no-load torque of 2.6 N.m; Under specific conditions of magnetic field strength and volume ratio, the torque transmitted by the coupling increases with the volume, for instance, when the volume of MRF is 50 mL and a motor speed of 600 r/min, the experimental prototype achieves a maximum torque value of 8.7 N.m, additionally, when the volume is constant, the torque transmitted by the experimental prototype remains basically unchanged with the change of slip speed, showing the characteristic of constant torque, this study offers theoretical and practical insights for the design and experimental analysis of similar products.

Research on a novel water-cooling multi-cylinder magnetorheological transmission device.

Power transmission is an important application for magnetorheological (MR) fluid, and the cylinder-type power transmission device is a novel transmission form due to its high stability, higher transmission torque, and large ratio of power to mass. This work designed a novel multi-cylinder transmission device with a water-cooling channel because the MR transmission device, especially high-power MR transmission device, inevitably works in the high-temperature environment. Based on Ohm's law and electromagnetism theory, the magnetic circuit in the novel MR transmission device is designed, and the magnetoresistance was calculated. The finite element method is used to analyze the magnetic field in the device to ensure that the magnetic field in the working gap of MR fluid is strong enough for the MR effects. The temperature of the MR fluid inside the device is analyzed by the finite element method in the natural cooling state and the water-cooling state, respectively, so as to obtain the performance of water cooling. The novel MR transmission device is manufactured to verify its power transmission capability and heat-dissipation performance. The experimental results show that the novel device can transmit a maximum torque of 70 N m, consistent with the rated torque. In addition, compared with natural cooling, the water cooling makes the temperature of the MR fluid to drop by 32.7% under the same working condition. This is the first time that the cooling channel is set up in the cylinder-type MR transmission device, which will provide a solution for the higher power transmission capacity by MR fluid.

The research of a multi-stage roller type magnetorheological transmission device on temperature properties

Magnetorheological Transmission Device (MRTD) is a controllable power regulation device using magnetorheological fluid as the transmission medium. It has characteristics of fast response, a wide range of speed regulations, and a pollution-free environment. The traditional pairwise transmission structure has serious heat generation problems during operation, resulting in low transmission efficiency. Therefore, we innovatively propose a multi-stage roller type MRTD to improve the heat generation problem fundamentally. The steady-state and transient temperature fields of the multi-stage roller type MRTD are simulated using the thermal analysis module in ANSYS based on the temperature field formulation. The variations of internal temperature at different slip powers are obtained. The results show that the designed multi-stage roller type MRTD has a good suppression of temperature rise. This study can provide a new approach to improve the thermal performance of MRTD.

A novel continuously variable-speed offshore wind turbine with magnetorheological transmission for optimal power extraction

ABSTRACT The paper introduces a novel magnetorheological transmission (MT) type offshore wind turbine (OWT), which integrates the MT into the traditional-geared train to construct a controllable power split type continuously variable gear train for the OWT. The design and construction of the MT-OWT are proposed. The continuous regulation of the transmission speed of the drive train is achieved by controlling the current of the MT. Then, a generalized utilization coefficient of wind power is defined to describe the overall efficiency of the OWT. A cooperative control strategy is proposed to track the optimal power points and capture the optimal wind kinetic energy with the best energy transmission efficiency by adjusting the electromagnetic torque and the MT of the OWT. The feasibility of the MT-OWT is verified through simulations. The results indicate that the maximum loads in the proposed MT-OWT can be reduced to be around 70% of the GT-OWT when adequate control is applied. Also, the generalized utilization coefficient of wind power can be well maintained around the rated value of around 0.45 and the generator speed can be well maintained around the rated value of around 1000 rpm (105 rad/s) regardless of the variations of the wind speeds and the turbine rotor speeds when using the proposed MT-OWT as compared with conventional OWT.

Performances of Planetary Magnetorheological Transmission Devices

Magnetorheological transmission devices (MRTDs) are a type of power transmission device using magnetorheological fluids (MRFs) as the transmission medium, which have the advantages of rapid response and continuously adjustable output performances. A new type of structure of planetary MRTDs is proposed to improve the performances of MRTDs in this study. A planetary MRTD was fabricated, and the performances of it were tested on the self-made testing system. The experimental results show that the continuously variable transmission of MRTDs under constant torque can be realized by adjusting the excitation current. The output speed or torque can be adjusted by adjusting the control current when the input speed is constant. The output torque increases with the increase in the input speed when the excitation current is constant. The performances of the MRTD were analyzed according to the properties of MRFs in complex flow and magnetic field. MRFs in complex flow and magnetic fields can produce more stable and higher responses to external magnetic fields than being simple sheared; thus, the planetary MRTDs have better performances and are useful structures for the application of MRFs in transmission.

Research on Magnetic Field of Multistage Counter Roll Magnetorheological Fluid Transmission Device

Aiming to solve the problem of magnetorheological transmission heat dissipation, a novel magnetorheological fluid transmission device is designed, and the torque of the device is analyzed. Based on electromagnetic theory, the magnetic circuit of the device is designed. The finite element method is used to simulate the magnetic field of the measurement device. Results show that the working magnetic induction can reach 0.5 T when the current is 1.6 A, which can meet design requirements. The magnetic induction intensity in the working space increases with the increase of the excitation current and permeability of the magnetic conductive material; decreases with the increase of the size of the working space; and increases with the increase of the size of the magnetic ring. The magnetic induction intensity in the working area is DT4C, 20 steel, and 45 steel from strong to weak. The experimental results are consistent with the simulation.

A novel water-cooling magnetorheological transmission device

A novel water-cooling magnetorheological transmission device

Design of a novel magnetorheological transmission device

This paper presents a new approach in the design of a novel magnetorheological transmission device (MRTD) that employs electromagnetic coil as a part of the stator. MRTD is a torque transmission device which uses magnetorheological fluid (MR fluid) as the transmission medium. MRTD can provide controllable torque and speed by adjusting the external applied magnetic field. The novel MRTD operates under the combination of shear-squeeze mode of MR fluid, which improves the working performance and reduces the adverse effect of centrifugal force. In this study, modes of operation of MR fluids and design parameters of MRTD were described briefly. Next, the material selection was specified, magnetic circuit was conducted, as well as the theoretical torque of MRTD. Finite element analysis was created solving the total magnetic flux density within the MRTD. A prototype MRTD was fabricated, its transmission characteristics were analysed, which mainly included torque transmission and speed control analysis. The results show that torque increases gradually as the current increases, and torque is linear with respect to the input current. The output speed increases significantly with steps of (0.10 A) increment. With further increase, the MRTD can reach synchronous speed. The MRTD shows excellent performance for various application.

Synthesized micro-theoretical analysis of performance of magnetorheological fluids subjected to shear mode operation: transmission, slip and sedimentation characteristics

This paper aims to formulate a synthesized micro-theoretical analysis that consists of transmission, slip and sedimentation characteristics for the evaluation of the performance of magnetorheological fluids (MRFs) subjected to the shear mode operation. To begin, based on the magnetic dipole theory and the typical micro-structure of MRFs, the shear yield stress of MRFs is analyzed considering the contribution of the magnetic force, excluded-volume force and viscous force. Then, an improve micro-structure of MRFs that is in correspondence with the actual observation is built, and the slip power of MRFs per unit area that takes into account the friction of the particles, walls and carrier liquid is investigated. Moreover, the sedimentation characteristic of MRFs described by the sedimentation velocity of the particles with the coating is analyzed based on the Stokes’ rule. The main influencing factors, such as the magnetic field intensity, the volume fraction of particles, the radius of particles, the coating thickness, the shear strain and the shear strain rate, etc, are taken into account in the micro-theoretical analysis, and the effects of these factors on the transmission, slip and sedimentation characteristics of MRFs are investigated respectively. It shows that the micro-theoretical analysis can describe these characteristics of MRFs accurately and reasonably, and can effectively be utilized for the initial design and optimization of the performance of MRFs and the useful guidance on the external control of magnetorheological transmission devices.

Influence of Temperature on Torque Transmission Stability of Magnetorheological Fluid

Aiming to obtain the influence mechanism of temperature on the torque transmission stability of magnetorheological fluid, firstly, a magnetorheological transmission device and its test-bed are established, and then, the thermal expansion, temperature pressure effect, heat volatilization, viscosity temperature characteristic, magnetic temperature characteristic and other related temperature characteristics were experimented systematically. The results indicate that the thermal expansion rate of 30 wt% magnetorheological fluid is 6 % and 18 % respectively at 120°C and 220°C, and the working space pressure is 13 kPa when the temperature rises from 32°C to 63°C. The thermal volatilization rate is still lower than 1 % at 200°C for 8 hours. The viscosity of the silicone oil based magnetorheological fluid decreases by 78 % when the temperature increases from 20°C to 240°C, and the saturation magnetization decreased by 6.2 %, 13 % and 23 % respectively at 150°C, 250°C and 350°C. Furthermore, the temperature field distribution experiment shows that the highest temperature region is at the outer diameter of the disk and expands slowly along the radial direction. Moreover, compared with rotational speed, temperature is the main factor affecting the torque fluctuation of magnetorheological fluid.

Simulation and Analysis of Magnetic Circuit of Water-cooling Magnetorheological Fluid Transmission Device

Aiming to solve the problem of magnetorheological transmission heat dissipation, this study designs the magnetic circuit of a water-cooling magnetorheological transmission device based on fundamental electromagnetics theory. Finite element method is used to simulate the magnetic field of the measurement device. Results show that the working magnetic induction can reach 0.56 T when the current is 2.0 A, which can satisfy design requirements. The intensity of magnetic induction in the work space increases with the increase of excitation current and permeability of magnetically conductive material, whereas intensity decreases with the increase of work space size. The thickness and cross-sectional dimension of the guidepost group at the heat-dissipating unit have no significant effect on the intensity distribution of magnetic induction of the entire device.

Influence of wall characteristics on transmittable torque of magnetorheological fluid

Magnetorheological fluid is a controllable fluid that exhibits changeable yield stress and attractive rheological properties on the applied magnetic field. In order to enhance the yield stress of magnetorheological fluid and suppress wall slip effect in the case of transmission, the mechanism and corresponding influence factors of the wall slip effect were investigated theoretically and experimentally. Different transmittable disks and a magnetorheological transmission test-bed were built, and the influence of wall characteristics on the transmission capacity of magnetorheological fluids was investigated on the test-bed. The results showed that the material types, surface roughness, and surface textures of transmission wall have distinct influence on the transmission capacity of magnetorheological fluid. The transmission wall with a groove depth of 0.2 mm, higher material magnetic permeability, higher surface roughness, radial grooves at the surface, and higher groove density was determined as the best transmission wall.

Study on Preparation and Performance of MRF for Torque Transmission

Based on the requirements of torque transmission for stability and saturation magnetization of magnetorheological fluid (MRF), an orthogonal test was designed to arrange for the preparation of MRF. MRF was prepared by chemical co-precipitation method, in which Fe3O4 nano-particles were coated with polyethylene glycol(PEG-4000). The size and distribution of particles were observed by transmission electron microscope (TEM). The saturation magnetization was measured by vibrating sample magnetometer(VSM). Through analysis of variance of orthogonal test,an optimal method for preparing a highly stable and saturation magnetization MRF was summarized. Four main parameters in preparation of MRF were discussed, including the rate of amount of substance between Fe2+and Fe3+, the rate of amount of substance between PEG-4000 and Fe2+, reaction time and the reaction temperature. It has important practical significance on the study of magnetorheological transmission device.

Design and Experiment for Magnetorheological Transmission Device with Heat Pipes

Magnetorheological transmission device(MRTD) is a new type of intelligent transmission device with excellent performances. A new MRTD with heat pipes is designed. In this type of device, the MR fluid is taken as the torque transmission medium and the pin-fin heat pipes rotating with driving shaft are used as the heat-sinking tool. A prototype of MRTD with heat pipes is manufactured and its experiments are done. The results reveal that the transfer torque of MRTD can be controlled by adjusting the exciting electric current. MRTD has a good constant-torque performance and its transfer torque almost maintains a constant value with variation of slipping speed. The pin-fin heat pipe can cool the MRTD effectively and its heat-sinking capability improves with increasing of rotating speed, thus providing an effective method for solving the heating problem of transmission device.