KR100311735B1 - Brake apparatus used as load unit by using magneto-rheological fluid - Google Patents

Abstract

PURPOSE: A brake device used as a load unit by using magneto-rheological fluid is provided to keep normal speed of a rotary machine, and to control braking force conveniently by plural electric circuit parts and an electromagnet part. CONSTITUTION: A brake apparatus as a load unit is composed of MR(magneto-rheological) fluid having ferromagnetic particles; electromagnetic parts generating the magnetic field to change the viscosity of MR fluid; and a rotating shaft having a disk applying load and braking force to the magnetic field. The control system of the brake has a detecting sensor unit(20) outputting a voltage signal according to rotation of the rotating shaft, a comparator(30) outputting the difference value by comparing the voltage signal with the reference voltage, a control unit(40) controlling the value from the comparator, and a converter unit(50) supplying to electromagnetic parts by converting voltage into current. Load and braking force are controlled accurately by feedback controlling rotational speed of the rotating shaft.

Description

Braking system for both load device using magnetorheological fluid

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking device for a combined load device using a magnetorheological fluid that is easy to apply to precise position control of a rotating mechanical system. In particular, the present invention uses a characteristic of a magnetorheological fluid having a yield stress in a magnetic field. Braking system such as ABS brake system of automobiles, simulation of power transmission system such as engine, etc., or the braking system using a magnetorheological fluid that can be used equally to the load device capable of precise load control even when driving various simulators. It is about.

Looking at the application of the recent rotary machine technology, it is possible not only to improve the performance such as high power and high-speed rotation of the rotary machine system, but also to precisely control the position of the rotating body, to maintain a constant speed when the load changes to the rotary machine, and to operate the rotary system. Effective suppression of the generated vibrations has been of great interest.

In general, in a brake system of a car or a bicycle, braking force is applied to a brake drum by directly rubbing metal or rubber pads on a rotating body when braking is required on a rotating object. In addition, in a load device such as a simulation of a power transmission device, a load is applied to a rotating system by forcibly converting mechanical rotational energy into electrical energy by applying the principle of a generator.

However, since the braking device using the method described above uses mechanical friction, the material changes due to frictional heat. In other words, when mechanical friction is used to reduce the speed and torque of the braking device, all the energy lost is converted into thermal energy, so the temperature at the frictional part is rapidly increased. Can cause a change. In addition, such material changes may degrade the performance of the product, and may even cause the product to break.

In addition, the load device using the method as described above is not able to accurately apply the desired load due to the nonlinearity of the generator, and also to increase the large load because the capacity of the generator must be large to apply a large load. In addition, when there is a need to change the load depending on the situation, the method using the generator principle has a lot of difficulty in arbitrarily changing the desired load because the inconvenience of having to replace the hardware of the device again.

Therefore, in order to alleviate the above disadvantages, magnetorheological fluids are used among smart materials which are much more stable and effective than conventional hydraulic devices and motors, and the reaction speed of the system is faster.

Here, the magnetorheological fluid is a non-colloidal solution containing ferromagnetic particles having a size of 10 ^-4 to 10 ^-3 cm and has a viscosity of 0.20 to 0.30 Pa-sec at room temperature without applying a magnetic field at 150 to 250 kPa / m. When a magnetic field of (2-3kOe) is applied, it has a high yield stress of 50-100 kPa. In addition, magnetorheological fluids have a fast response time [1-2 msec (msec; 10 ^-3 sec)], although the maximum yield stress is limited by magnetic saturation, and also has an operating range of -40 to 150 ° C. And insensitive to incoming impurities.

In a magnetorheological fluid having such a property, when a magnetic field is applied, particles contained in the fluid form a chain, thereby changing the shear yield stress of the fluid. Therefore, when the magnetic field is not applied, it shows the behavior of Newtonian fluid, but when the magnetic field is applied, the particles dispersed in the fluid form a chain, which has yield stress even in the absence of shear strain and increases the angular velocity. It shows the behavior of the Bingham fluid with increasing dissipation torque. That is, the magnetorheological fluid changes from a liquid state to a gel state when the magnetic field is not applied.

As a damping device using a magnetorheological fluid according to the related art, for example, US Patent No. 4,200,003 of a magnetorheological damper, US Patent No. 4,942,947 using a permanent magnet and an electromagnetic coil to limit linear motion, and magnetorheological US Patent No. 5,284,330 using a valve mode of the fluid design method, US Patent No. 5,492,312 using a magnetorheological fluid to limit the reciprocating motion, and a magnetic field generated by the rotating disk and the solenoid US Patent No. 5,598,908, which is a torque rod simulator system with varying viscosity.

Typically, a device used in a rotating machine in such a conventional magnetorheological fluid damping device includes a rotating shaft including a disk to which an externally transmitted rotational force is applied, a body part filled with a magnetorheological fluid surrounding the disk, and such a body. It consists of an electromagnetic coil that can change the viscosity in direct shear mode by applying a magnetic field to the negative magnetorheological fluid.

However, the systems using a plurality of magnetorheological fluids are merely used as damping devices and braking devices that simply generate a magnetic field that changes viscosity and thus suppress reciprocation or rotational motion.

In addition, the systems use only the principle of the change of the viscosity of the magnetorheological fluid in application to a load device that rotates the mechanical device at a constant speed. Therefore, the systems are weak in the configuration for adjusting the constant speed of the load device and the braking force of the braking device. There are disadvantages.

An object of the present invention is to maintain any constant speed of a rotating machine and to easily control braking force with a plurality of electric circuit parts composed of a feedback closed circuit and an electromagnet part for changing the viscosity of a magnetorheological fluid to solve the problems of the prior art as described above. To provide a load device and a braking device using a magnetorheological fluid.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram illustrating a control system of a braking device for a combined load device using a magnetorheological fluid according to a first embodiment of the present invention.

Figure 2 is a cross-sectional view for explaining the configuration of the braking device for a combined load device using a magnetorheological fluid shown in FIG.

FIG. 3 is a cross-sectional view illustrating important parts of a combined brake device using a magnetorheological fluid shown in FIG. 2.

Figure 4 is a cross-sectional view for explaining the configuration of a braking device for a load device using a magnetorheological fluid according to a second embodiment of the present invention.

♠ Explanation of symbols on the main parts of the drawing ♠

10: main body 11: rotation axis

14: electromagnetic coil bobbin 14a: electronic coil

15: negative 16,16 ': magnetorheological fluid

20: sensor unit 30: comparison circuit

40: control unit 50: voltage / current converter

60: permanent magnet 70: generator

According to the present invention for achieving the object as described above, a magnetorheological fluid having ferromagnetic particles, an electromagnet portion for generating a magnetic field for changing the viscosity of the magnetorheological fluid, a load and A braking device for a combined load device using a magnetorheological fluid that attenuates the rotational force transmitted from the outside to a main body having a rotating shaft on which a disk for applying braking force is provided, wherein the rotational speed or the rotational force of the rotating shaft is sensed and a voltage signal accordingly is detected. A sensing sensor unit for generating a; and a comparison circuit unit for outputting a difference value by comparing the voltage signal of the sensing sensor unit with a reference input voltage, a controller for controlling an output value of the comparison circuit unit, and a proportional to the output control voltage of the controller. The controller converts the voltage of the external power supply into a current and supplies it to the electromagnet of the main body. The rotor part constitutes a feedback closed circuit, and by feeding back the rotational speed or the rotational force of the rotary shaft by an external rotational force to the sensing sensor unit, the comparison circuit unit, the control unit and the converter unit, it is possible to accurately control the amount of load and braking force. Provided is a braking device for a load device using a magnetorheological fluid.

In addition, according to the present invention, it is preferable that the main body portion is attached to a permanent magnet for generating a magnetic field in order to suppress the magnetorheological fluid leaked from the large circumferential surface of the rotating shaft and the inner circumferential surface of the bearing fixed to the body portion. .

In addition, according to the present invention, it is preferable that a small peripheral surface is formed on the rotating shaft so that the magnetic room of the permanent magnet can change the viscosity of the magnetorheological fluid leaked from the inner peripheral surface of the bearing.

In addition, according to the present invention, there is provided a magnetorheological fluid having ferromagnetic particles, an electromagnet portion for generating a magnetic field for changing the viscosity of the magnetorheological fluid, and a rotating shaft having a disk for applying load and braking force to the magnetic field. In the braking device for a combined load device using a magnetorheological fluid that attenuates the rotational force transmitted from the outside to the rotating shaft to the main body provided, the coil portion and the magnet portion for supplying a current to generate a magnetic field of the electromagnet portion at the end of the rotating shaft The generator is coupled to the generator, the generator is provided with a load device combined braking device using a magnetorheological fluid, characterized in that the rotating shaft can rotate at a constant speed by supplying a current proportional to the rotational force of the rotating shaft to the electromagnet. do.

In the following, with reference to the accompanying drawings, preferred embodiments of the braking device combined load device using a magnetorheological fluid according to the present invention will be described in detail.

<First Embodiment>

In the drawings, FIG. 1 is a block diagram illustrating a control system of a brake device using a magnetorheological fluid according to a first embodiment of the present invention, and FIG. 2 is a load using a magnetorheological fluid shown in FIG. It is sectional drawing for demonstrating the structure of a combined brake apparatus.

The braking device for a load device using the magnetorheological fluid of the present invention described in this embodiment is provided with a sensor detecting unit for measuring a rotational speed of an axis to which an external force is applied, and a comparison circuit unit for supplying a reference input voltage. It is the same as the prior art except for including a comparator, a control unit, and a voltage / current converting unit and sealing the magnetorheological fluid using a permanent magnet.

1 and 2, the braking device using the magnetorheological fluid according to the first embodiment of the present invention attenuates the rotational force transmitted from the outside to the magnetorheological fluid 16 and a magnetic field m of a predetermined size Feedback unit consisting of a main body unit 10, a sensor unit 20, a comparator 30, a control unit 40, and a voltage / current converter 50 so as to control the main body unit 10 in a feedback-controlled manner. It forms a closed circuit.

The sensor unit 20 is disposed on the rotation shaft 11 of the main body 10. The sensor 20 is of the same type as a conventional encoder that detects the rotational speed of the rotary shaft 11 and generates a signal having a voltage of a predetermined size.

In addition, the comparator 30 electrically connected to the sensing sensor unit 20 is electrically connected to a reference input voltage 35 that allows the rotary shaft 11 to operate at a constant speed or as intended by the designer. The comparator 30 is configured to transmit the difference between the two signals to the controller 40 by comparing the difference between the magnitude of the voltage fed back from the sensing sensor unit 20 and the reference input voltage 35.

In addition, the control unit 40 is a conventional control circuit that can control the entire feedback type closed circuit to adjust the size of the magnetic field of the main body unit 10. The control unit 40 may be designed in a number of control methods for adjusting the operation of the main body unit 10 as the designer intended. For example, the controller 40 controls the operation of the operation of the main body 10 programmed with the data of the time table, or the comparator such that the main body 10 has a constant torque value and a constant speed. The voltage signal input at 30 is controlled. In addition, the control unit 40 is electrically connected to control the voltage signal of the comparator 30 to generate a control voltage signal, and to supply the control voltage signal to the electrically connected voltage / current converter 50. have.

In addition, such a voltage / current converter 50 is an electromagnetic coil 14a of the external power source 55 and the electromagnetic coil bobbin 14 to form a magnetic field m in the electromagnetic coil bobbin 14 of the main body 10. Is electrically connected). The voltage / current converter 50 receives an amplified voltage signal proportional to the control voltage signal supplied from the controller 40 from the external power supply 55 and converts the amplified voltage signal into a current signal.

As shown in FIGS. 2 and 3, the main body 10 of the braking device using the magnetorheological fluid of the present invention configured as described above has a magnetorheological fluid 16, a rotating shaft 11, and a disc 15. And the electromagnetic coil bobbin 14 having a circular ring shape are formed. In the center of the main body portion 10, the rotating shaft 11 is arranged to be rotatable by the bearing 13. The rotary shafts 11 thus arranged are formed to have different diameters as the major circumferential surface 11a and the minor circumferential surface 11b. In addition, the disc 15 is integrally formed at the center of the rotating shaft 11.

The magnetorheological fluid 16 surrounding the disc 15 of the rotary shaft 11 is filled in a predetermined space formed inside the main body 10, the magnetorheological fluid 16 is the disc 15 of the rotary shaft 11 A thin oil layer is formed in a predetermined space formed on the surface and inside the main body portion 10. The upper end of the rotary shaft 11 is attached with a conventional mechanical coupling means 12, such as a pulley to which an external load can be transmitted, and a sensing sensor unit at the end of the downward circumferential surface 11b. 20 is arranged.

In addition, the main body portion 10 is disposed with a circular ring-shaped electromagnetic coil bobbin 14 having a diameter relatively larger than the diameter of the disk 15 of the rotating shaft 11. The electromagnetic coil 14a is wound around the electromagnetic coil bobbin 14 so as to generate a magnetic field m according to the amount of current supplied from the voltage / current converter 50. In addition, the body portion 10 surrounding the electromagnetic coil bobbin 14 is wrapped with a ferromagnetic material in order to improve the flow of the magnetic field (m) generated in the electromagnetic coil bobbin 14.

In the following, the coupling relationship between the main parts of the main body of the braking device for the combined load device using the magnetorheological fluid according to the first embodiment of the present invention arranged as described above will be described.

First, FIG. 3 is an enlarged view of a circle A shown in FIG. 2 to explain a sealing of a brake device using a magnetorheological fluid according to a first embodiment of the present invention.

As shown in FIG. 3, the circle A is attached to the main body portion 10 with bearings 13 capable of freely rotating the rotating shaft 11. In addition, the inner circumferential surface of these bearings 13 is coupled to the large circumferential surface 11a of the rotary shaft 11 by fitting fit. In addition, a ring-shaped permanent magnet 60 is attached to the outer surface of the main body portion 10 having the inlet 17 through which the small circumferential surface 11b of the rotary shaft 11 penetrates downward. The permanent magnet 60 generates a magnetic field f of a predetermined size to prevent leakage of the magnetorheological fluid 16 to the outside of the main body 10. Therefore, the magnetic field f of the permanent magnet 60 passes through the magnetorheological fluid 16 'leaked at the site where the small circumferential surface 11b of the rotating shaft 11 and the bearing 13 are fitted by fitting. The magnetic field f of the permanent magnet 60 changes the viscosity of the magnetorheological fluid 16 ′.

In the following, the operation method of the combined brake device using the load device using the magnetorheological fluid according to the first embodiment of the present invention as described above will be described in detail.

First, the rotating shaft 11 of the main body portion 10 is rotated in a predetermined direction (a) by applying a rotational force from the outside. At this time, when the operator turns on the combined braking device of the load device according to the first embodiment of the present invention, the voltage / current converter 50 is a current of 1 ~ 2A that can be applied to the precise position control of the rotating mechanical system Supply to the electromagnetic coil bobbin 14 of the body portion 10. In addition, the electromagnetic coil bobbin 14 of the body portion 10 generates a tubular magnetic field m of a predetermined size. This magnetic field (m) passes through the magnetorheological fluid 16 and the disk 15 of the rotating shaft 11 filled in the body portion 10. At this time, the external rotating force is applied to the rotating shaft 11 is rotated in the a direction by the magnetic field (m) generated in the electromagnetic coil bobbin 14 is generated a considerable amount of braking force.

In addition, when an irregular load and rotational force are applied to the rotary shaft 11 again, the rotary shaft 11 changes in an irregular speed. At the same time, the sensor unit 20 coupled to the rotating shaft 11 converts the speed of the rotating shaft 11 into a voltage signal and sends the converted voltage signal to the comparator 30 electrically connected thereto. The comparator 30 compares the input voltage 35 and the voltage signal input so that the rotating shaft 11 of the main body 10 rotates at a constant speed, and sends the difference value to the controller 40. The controller 40 sends the control voltage corresponding to the difference value of the comparator 30 to the voltage / current converter 50 again. The voltage / current converter 50 converts the voltage of the external power source 55 proportional to the control voltage into a current and sends it to the main body 10. In this way, the electromagnetic coil bobbin 14 of the main body unit 10 generates a magnetic field m of a size capable of reducing the irregular load and the external rotational force by the current value by the external power source 55 proportional to the control voltage. Let's do it. Therefore, the rotating shaft 11 of the main body portion 10 is rotated at a constant speed.

In addition, the magnetic field f of the permanent magnet 60 attached to the main body 10 is the magnetorheological fluid 16 leaked at the site where the bearing 13 and the major circumferential surface 11b of the rotary shaft 11 are coupled. ') Penetrates vertically to increase the viscosity. Therefore, the magnetic field f of the permanent magnet 60 is a magnetorheological fluid whose viscosity is largely changed because the amount of leakage and internal pressure of the magnetorheological fluid 16 'is relatively small on the surface of the major circumferential surface 11b. The 16 'is not allowed to leak out of the main body portion 10.

In addition, in the same manner as described above, the braking device using the magnetorheological fluid according to the first embodiment of the present invention uses the rotating shaft 11 due to the viscosity change of the magnetorheological fluid caused by the magnetic field m of the electromagnetic coil bobbin 14. To generate braking force. In addition, such a braking device using a magnetorheological fluid reacts to such an electrical signal very quickly since the rotation of the rotating shaft 11 of the main body 10 is controlled by an electrical signal by the sensing sensor unit 20. Viscosity change of the magnetorheological fluid 16 can be sensitively controlled to change in external rotational force. Therefore, the braking device for the combined load device using the magnetorheological fluid of the present invention can be applied to a brake system such as an ABS device that requires a change in braking force for several tens of times per second to apply a relatively very fast and repetitive braking force.

The sensing sensor unit of the braking device for the combined load device using the magnetorheological fluid of the present invention is not limited to converting the rotational speed of the rotating shaft into a voltage signal, and can measure a physical quantity such as torque related to the rotating shaft to be changed into voltage or current. Identify the sensor.

Second Embodiment

4 is a cross-sectional view for explaining the configuration of a brake device combined with a load device using a magnetorheological fluid according to a second embodiment of the present invention.

The braking device for the combined load device using the magnetorheological fluid of the present invention described in this embodiment has the exception that a small generator which generates a current proportional to the rotational speed is used in place of the sensor unit used in the first embodiment. It is the same as the braking device combined with the load device using the magnetorheological fluid according to the first embodiment of the present invention. Therefore, the same or similar reference numerals will be given to the same or corresponding components in FIGS. 1 to 4, and the description thereof will be omitted here.

As shown in FIG. 4, in the braking device for a load device using the magnetorheological fluid according to the second embodiment of the present invention, a conventional generator is disposed at an end portion of the rotary shaft in a downward direction.

This generator 70 is composed of a coil portion 71 which can be coupled to the end of the rotating shaft 11 as a reverse type of a conventional motor and a magnet portion 72 having an N pole and an S pole in a normal permanent stone. When the coil part 71 is rotated in the magnet part 72, a current that is proportional to the rotational speed of the rotating shaft 11 flows into the coil part 71. Such a generator 70 can be used as a speed sensor because the increase and decrease of the amount of current flowing into the coil portion 71 is proportional to the rotational speed of the rotating shaft 11, and is also simple for such a generator 70. Since the circuit can convert the current into a voltage, it can perform the same function as the existing speed sensor 20.

In addition, such a generator 70 is used not only as a speed measuring device but also as a current source of a braking device for a combined load device using a magnetorheological fluid according to the second embodiment. This generator 70 is a capacity capable of generating a current of a magnitude greater than the current of 1 to 2A flowing along the electromagnetic coil 14a in the main body portion 10 of the combined brake device. Accordingly, the generator 70 may serve as a current sensor and a speed sensor as well as serve as a current source of the braking device for a load device using the magnetorheological fluid according to the second embodiment.

In the following, the coupling relationship and the operating method of the combined braking device of the load device using the magnetorheological fluid according to the second embodiment of the present invention as described above will be described.

As shown in Fig. 4, the coil portion 71 of the generator 70 is inserted into and attached to the small circumferential surface 11a of the rotating shaft 11 of the same main body as in the first embodiment. The coil portion 71 of the generator 70 is coupled to rotate in a non-contact manner inside the magnet portion 72. In addition, the coil part 71 is connected with the electromagnetic coil 14a of the electromagnetic coil bobbin 14 of the said main-body part 10 through the electric wire 73 so that an electric current may flow to the exterior by the conventional brush contact method.

The generator 70 coupled as described above has a current proportional to the predetermined speed of the rotating shaft 11 when the rotating shaft 11 rotates at a predetermined speed with a predetermined direction by external rotational force or disturbance. Generate. The generated current flows back to the electromagnetic coil 14a of the main body 10 through the electric wire 73, and the magnetic field m 'is formed in the electromagnetic coil bobbin 14 of the main body 10. do. This magnetic field m 'converts the viscosity of the magnetorheological fluid 16 filled in the body portion 10 to reduce the irregular load and external rotational force. Therefore, the combined brake device using the magnetorheological fluid according to the second embodiment of the present invention having the generator 70 as its own current source efficiently rotates the rotary shaft 11 at a constant speed to generate load and braking force.

The generator of the braking device of the combined load device using the magnetorheological fluid of the present invention is not limited to only coupling to the rotating shaft, but it can be coupled to any part of the main body to obtain the rotating force of the rotating shaft.

As described in detail above, the combined braking device using the magnetorheological fluid of the present invention can simultaneously perform the role of the conventional mechanical load device and the braking device with a small volume and a simple configuration, and heat, noise, and vibration caused by friction Since it does not occur, the safety of the device and the quality of the product can be greatly improved.

In addition, the braking device for a load device using the magnetorheological fluid includes a sensor unit, a comparator, a controller and a voltage / current converter fed back to the closed loop in order to accurately control the operation of the main body using the magnetorheological fluid and the electromagnetic coil. Since it includes a precise control of the rotational force applied to the rotating shaft has the advantage of generating a load and braking force of the desired size.

In addition, the braking device for the combined load device using the magnetorheological fluid of the present invention has a merit that a very efficient role can be performed because a generator using the rotational force of the rotating shaft makes a magnetic field necessary for the viscosity change of the magnetorheological fluid.

In addition, the braking device for the combined load device using the magnetorheological fluid of the present invention has the advantage of sealing the magnetorheological fluid without applying a large friction force because the permanent magnet is attached to the outside of the main body portion coupled to the rotating shaft.

In addition, the combined braking device of the load device using the magnetorheological fluid of the present invention has a very wide application field, and thus has a great ripple effect in the industrial field.

In the above description, the technical idea of the braking device for a combined load device using the magnetorheological fluid of the present invention has been described with the accompanying drawings. However, the present invention has been described by way of example and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (4)

Magnetorheological fluid (16) having ferromagnetic particles, electromagnet parts (14,14a) for generating a magnetic field (m) for changing the viscosity of the magnetorheological fluid (16), and the magnetic field (m). In the braking device for a combined load device using a magnetorheological fluid that attenuates the rotational force transmitted from the outside to the main body portion 10 having a rotating shaft 11 having a disc 15 for applying the load and braking force, The difference value of the sensing sensor unit 20 for detecting the rotational speed or the rotational force of the rotary shaft 11 and generating a voltage signal according thereto, and comparing the voltage signal of the sensing sensor unit 20 with the reference input voltage 35. Converts the voltage of the comparison circuit unit 30 for outputting the control unit, the control unit 40 for controlling the output value of the comparison circuit unit 30, and the external power source 55 proportional to the output control voltage of the control unit 40 to current. The converter unit 50, which is supplied to the electromagnet units 14 and 14a of the main body unit 10, constitutes a feedback closed circuit, Accurate load amount and braking force by feeding back the rotational speed or rotational force of the rotary shaft 11 by the external rotational force to the sensing sensor unit 20, the comparison circuit unit 30, the control unit 40 and the converter unit 50. Combined braking device with a load device using a magnetorheological fluid, characterized in that to control the. 2. The magnetorheological fluid 16 'according to claim 1, wherein the main body portion 10 leaks from the large circumferential surface 11a of the rotating shaft 11 and the inner circumferential surface of the bearing 13 fixed to the main body portion 10. Combined braking device using a magnetorheological fluid, characterized in that the permanent magnet (60) for generating a magnetic field (f) is attached to suppress). The surface of the wishing circumferential surface of claim 2, wherein the magnetic field f of the permanent magnet 60 in the rotating shaft 11 can change the viscosity of the magnetorheological fluid 16 'leaked from the inner circumferential surface of the bearing 13. A braking device for use with a load device using a magnetorheological fluid, characterized in that (11b) is formed. Magnetorheological fluid (16) having ferromagnetic particles, electromagnet parts (14,14a) for generating a magnetic field (m ') for changing the viscosity of the magnetorheological fluid (16), and the magnetic field (m'). Combined with a load device using a magnetorheological fluid that attenuates the rotational force transmitted to the rotating shaft 11 from the outside to the main body portion 10 having a rotating shaft 11 formed with a disc 15 for applying a load and a braking force to the) In the braking device, At the end of the rotating shaft 11 is coupled a coil unit 71 for supplying a current for generating a magnetic field m 'of the electromagnet portions 14 and 14a and a generator 70 having a magnet portion 72. The generator 60 supplies a magnetorheological fluid, in which the rotating shaft 11 can rotate at a constant speed by supplying a current proportional to the rotational force of the rotating shaft 11 to the electromagnet portions 14 and 14a. Combined braking system with load device.

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