MAGNETORHEOLOGICAL FLUIDS AND DEVICES

MAGNETORHEOLOGICAL FLUID DEFINITION

Magnetorheological fluid is a suspension of magnetic parts (restored iron, pure iron, cobalt, carbonyl iron, nickel) about 0.1 … 100 microns in fluid carriers.

MAGNETORHEOLOGICAL FLUID FEATURES

When imposing a magnetic field, magnetorheological fluid can change a fluidity limit, depending on its physical and chemical structure from 0 to 50 … 100 kPa.

ADVANTAGES OF MAGNETORHEOLOGICAL FLUID

high aggregate stability in magnetic field;
opportunity to transfer high circumferential stress;
high response time;

DEVICES IN WHICH IT IS EXPEDIENT TO USE MAGNETORHEOLOGICAL FLUID

The most popular devices with use are magnetorheological dampers, magnetorheological shock-absorbers, magnetorheological supports, magnetorheological couplings and brakes. And now they are widely applied abroad in various spheres of the industry and equipment. Most visually properties of fluid are shown in illustrations.

Example of magnetorheological fluid behavior in magnetic field in magnetorheological couplings and brakes.

Example of magnetorheological fluid behavior in magnetorheological dampers and shock-absorbers.

Schematic diagrams of the main devices in which magnetorheological fluid is applied, are provided.

Coupling circuit

Brake circuit

Damper circuit

Automobile manufacturing

Magnetic active suspension

The system of movement stabilization of the vehicle with Delphi MagneRideTM magnetic active suspension bracket represents the system of magnetorheological dampers, which are operated and controlled by the microcontroller, in a simpler way. It allows to significantly reduce vibrations at the movement of the vehicle, to make a trip comfortable, and also to increase a resource of working assemblies in the car.

Vehicles, at which the active magnetic suspension bracket was set.

Magnetorheological differential lock clutch Advantages of this type of clutches: simplicity of design; possibility of transfer of the high torques; high speed of clutch operation; possibility of electronics control; zero lag.

The first commercially successful model is the differential lock clutch, developed and manufactured by Magna Powertrain (Germany) in 2008.)

In 2005 RICARDO experimental design bureau RICARDO (England) presented the development of differential with the magnetorheological clutch for BMW X5,

The tests showed the excellent running characteristics. Final tests of the vehicle are executed now.

Magnetorheological vibratory bearings, at which the engine is set (it is developed for Porsche GT 911 serial model)

Robotics technology

Use in industrial robot units. The differential with a magnetorheological brake allowed to refuse from the use of a large number of hydraulic cylinders, simplified the design, and increased the speed of simulator operation. The robot unit developed by Japanese engineers is created for parts and work pieces supply in the processing centers. The magnetorheological brake executes the function of regulator. Magnetorheological brake blocks the robot unit operation in case of damage or emergency. These brakes can effectively replace or supplement the standard decisions.

Exoskeletons.

The first commercially successful exoskeletons were created in 2006 by Japanese company Cyberdyne Inc.

Exoskeleton is the complex symbiosis of human nervous system, biomechanics, electronics and mechanics.

One of important executive mechanisms of exoskeleton is the magnetorheological clutch in all hinged connections. The essence of development is that this mechatronic system allows to facilitate the walking of sick patients. The magnetorheological clutch carries out function of the shock-absorber in knee and elbow joints of exoskeleton. Also these exoskeletons expand the human physical capacities.

Mechanic engineering and machine tool technology

Adaptive vibration control during boring and deep drilling. Use of adaptive mechatronic system with magnetorheological clutch for exact processing of details protects from tool failure, at tool blunting the cutting moment increases, moment sensor transmits a signal to the machine computer, further data are processed and the control signals are going to magnetorheological clutch. Depending from criticality of cutting modes and conditions the clutch microcontroller gives out the commands to suppress the fluctuations, or to reduce the rotation frequency, providing spin-out, thus reducing the load to the tool.

Hexapod machine and Stewart platform. Stewart platform has six degrees of freedom (three forward and three rotary, as a rigid body). The mechanism has six independent feet at hinged connections. Changing the length of feet, it is possible to change the platform orientation.

Burnishing and execution of finishing operations with the help of magnetorheological fluid. Abrasive parts are added to magnetorheological fluid and by means of magnetic field are brought to the processed detail. By means of magnetorheological fluid it is possible to process even very difficult surfaces.

Other scopes (aircraft, shipbuilding, architecture, medicine)

Artificial limbs and knee joints (medicine)
Magnetorheological dampers at active control of fluctuations and vibration in household and industrial washing machines (household appliances)
Loading brake in exercycle design (home gym)
Steer-by-wire device (tactile control)
Active vibration control and absorbing of vibration of ship and aviation units and mechanisms.
Suppression of fluctuations in construction designs

Our projects

Magnetorheological fluid

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Magnetorheological fluids at the basis of synthetic and organic-silicon oils are developed and manufactured for research of clutches.
Fluids showed satisfactory sedimentatsionny firmness, and opportunity to transfer the great tangential shearing stress.

Magnetorheological clutches
The disk magnetorheological clutch with adjustable working gap.

The working gap of the coupling is filled with magnetorheological fluid. At the switched-off excitating winding the leading part rotates freely and the coupling does not transfer the rotating moment.

At current supply to excitating winding the power lines of magnetic field (created by excitating winding), passes through the case, leader and conducted parts, constructive and working gaps. Magnetorheological fluid, which is in a working gap, has the increased viscosity due to structuring magnetic parts in a magnetic field, owing to what there is a coupling of the leader and the conducted part of the coupling.

Overall dimensions of the clutch: maximum diameter – 180 mm, length – 260 mm. Outer diameter of working disk – 85 mm. Clutch transfer moment – 10 N m.

The clutch is protected by patents of Ukraine.

Cylindrical magnetorheological clutch.

For testing of big rotating moments, and also fluid behavior in braking process, the cylindrical clutch was designed (which can be used as a brake).

The design is executed with the rotating case and excitating winding. Current moves to excitating winding via the brush gear. The size of working gap, assembly accuracy, and also the inspection of used magnetorheological fluid was executed through survey openings.

Clutch transfer moment 50 N m.

During the development process, the clutches were optimized by means of applied programs packages, which implement the final elements method.

Magnetorheological fluids and devices