JPH1182501A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high withstand load in a low cost and suppress a vibration, by providing a shaft, a bearing pivoting the shaft, an ER fluid of which viscosity is changed by impressed voltage, and electrodes and power source impressing the ER fluid with voltage, and arranging the ER fluid in the axial direction near the bearing. SOLUTION: A shaft 2 is rotatively supported by a bearing 3, and a spacer 7 which is a first insulator and a spacer 8 which is a second insulator are provided on the upper side of the bearing 3. Between the spacer 7 and the spacer 8, an electrode 9 is provided and an ER fluid 10 is filled. A first insulating spacer 11 and a second insulating spacer 12 are provided on the lower side of the bearing 3. Between the spacer 11 and the spacer 12, an electrode 13 is provided and the ER fluid 10 is filled. When voltage is impressed on the shaft 2 and the electrodes 9, 13, viscosity of the ER fluid 10 is reversibly changed, and magnitude of load received by the fluid is changed. Thus, the control of voltage enables the control of the weight of the receivable load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing, and more particularly to an electrorheological fluid (hereinafter abbreviated as ER fluid) on an end face of a sliding bearing.
The present invention relates to a bearing device that realizes high precision and high reliability by a combination of a plain bearing and an ER fluid bearing.

[0002]

2. Description of the Related Art Sliding bearings are often used as bearings for small motors used in information equipment. Among these, oil-impregnated bearings in which a porous body is impregnated with lubricating oil are inexpensive and widely used. For example, a dynamic pressure bearing is used as a bearing of a motor for a polygon mirror of a laser printer that requires precise rotation. A spindle motor of a CD-ROM, which is an external storage device of a computer, is about to use a dynamic pressure bearing for a high-speed rotation of the motor in response to a demand for an improvement in access speed.

[0003]

However, the above-mentioned oil-impregnated bearing has a structure in which there is a gap between the shaft and the bearing, so that the split shaft of this gap is moved to one side to perform a sliding motion, so that precise rotation becomes difficult. In addition, the oil-impregnated bearing has a problem in that the shaft and the bearing are not in a completely non-contact state, and are worn due to contact between the shaft and the bearing, making it difficult to maintain accuracy. For example, in the bearing of a spindle motor of a CD-ROM, there is a problem that a large unbalanced load is applied during high-speed rotation due to imbalance of a disk, thereby deteriorating the bearing accuracy, and a problem of deteriorating a read signal due to vibration. In order to improve this point, there is a hydrodynamic bearing that can rotate in a non-contact state, but the hydrodynamic bearing is difficult to manufacture and therefore expensive. In addition, since no dynamic pressure is generated at the time of starting and stopping, there is a problem that the shaft and the bearing come into contact with each other and the wear deteriorates the accuracy and shortens the service life similarly to the sliding bearing.

The present invention solves such a problem, and provides a bearing which is inexpensive, has a high withstand load, suppresses vibration, obtains high-precision rotation, and has a long life and high reliability. Things.

[0005]

According to a first aspect of the present invention, there is provided a bearing device comprising: a shaft; a bearing for supporting the shaft in rotation; an ER fluid whose viscosity changes when a voltage is applied; ER fluid is provided in the axial direction near the bearing.

According to the above construction, the shaft is supported by combining the bearing and the ER fluid whose viscosity changes by applying a voltage, so that the load-loading capability of the bearing is added to the load-loading capability of the bearing. , Load capacity and bearing rigidity are improved. Also, by applying a voltage to the ER fluid, the viscosity of the ER fluid rises and the shaft is supported by the ER fluid,
The contact between the shaft and the bearing is reduced, and wear can be prevented. Also, E
Since there is no clearance between the R fluid and the shaft, vibration is prevented by always supporting the shaft, and high-precision rotation is obtained. Further, by arranging the ER fluid in the axial direction of the bearing, the lubricating oil used in the bearing is sealed by the ER fluid, so that leakage of the lubricant can be prevented.

According to a second aspect of the present invention, there is provided a bearing device comprising: a shaft; a bearing for rotatably supporting the shaft; first and second electric insulators provided on end surfaces of the bearing; and first and second insulators An electrode made of a conductor sandwiched between the ER fluid, an ER fluid filled between a shaft and the first and second insulators and in a space surrounded by the electrode and having a viscosity changed by applying a voltage, and an ER fluid between the shaft and the electrode. A power supply for applying a voltage to the power supply.

According to the above construction, the same effect as that of the first aspect can be obtained. In addition, an electrode sandwiched between insulators is arranged on the end face of the bearing to fill the ER fluid, and the voltage is applied in the radial direction of the bearing. Is applied, so that a higher load and a sealing property are further improved.

According to a third aspect of the present invention, there is provided a bearing device comprising: a shaft; a bearing for rotatably supporting the shaft; and first and second shafts provided on end surfaces of the bearing.
And a third electrical insulator, a first electrode composed of a conductor sandwiched between the first and third electrical insulators, and a second electrode composed of a conductor sandwiched between the second and third insulators An ER fluid filled in a space surrounded by the shaft, the third insulator, and the first and second electrodes and having a viscosity changed by applying a voltage; a first electrode and a second electrode A power supply for applying a voltage therebetween.

According to the above configuration, not only the same effects as those of the first aspect are obtained, but also the configuration in which the electrodes are arranged along the axial direction eliminates the need to apply a voltage to the rotating bearing, thereby simplifying the configuration. become. Further, there is an effect that the electrode configuration is simplified and the productivity is excellent.

According to a fourth aspect of the present invention, there is provided a bearing device comprising: a shaft; a bearing for rotatably supporting the shaft; and first and second shafts provided on end surfaces of the bearing.
An electrode comprising a plurality of conductors extending between the third electrical insulator and the shaft, which are sandwiched between the first and second electrical insulators, and extending in the axial direction; And an ER fluid whose viscosity changes by applying a voltage filled in a space surrounded by the shaft and the third insulator, and a power supply for applying a voltage between the plurality of electrodes.

According to the above configuration, not only effects equivalent to those of the first and third aspects are obtained, but also high-precision rotation is obtained by the centering action of the shaft due to the flow swirling along the rotating shaft. . Further, there is an effect that the friction loss between the shaft and the bearing can be reduced by the swirling flow.

According to a fifth aspect of the present invention, the bearing is a plain bearing.

According to the above configuration, there are problems in oil-impregnated bearings that cannot withstand a large load and that the accuracy deteriorates due to wear, and in the abrasion of the shaft and the bearing at the time of starting and stopping, and in the sealing property of the lubricating oil. Combining the present invention with a plain bearing such as a dynamic pressure bearing having an effect has an effect that a high-performance bearing can be obtained at low cost.

According to a sixth aspect of the present invention, an insulator, an electrode, and an ER fluid are provided on both end surfaces of the bearing.

According to the above construction, the bearing device of the present invention has a sufficient effect even if it is arranged on one side of the bearing, but has a greater effect if it is arranged on both end surfaces of the bearing.

According to a seventh aspect of the present invention, a conductive metal foil bonded to an insulator made of a resin is formed in a desired shape, the insulator is a first insulator, and the conductive metal foil is a first electrode. Alternatively, the insulator is a second insulator, and the conductive metal foil is a second electrode.

According to the above structure, there is an effect that the structure can be easily manufactured by simplifying the structure of the insulator and the electrode.

According to an eighth aspect of the present invention, in the bearing device, a plurality of electrodes extending in the axial direction are formed in a desired shape on the third insulator.

According to the above configuration, there is an effect that manufacture of the electrode is easy.

According to a ninth aspect of the present invention, there is provided a bearing device, wherein a means for detecting the rotational speed of the shaft is provided, and the applied voltage of the ER fluid is controlled according to a change in the state of the bearing device.

According to the above configuration, optimal control can be performed according to the state of the bearing.

According to a tenth aspect of the present invention, the detection of the rotational speed of the shaft uses a back electromotive force of a permanent magnet for the field of the motor.

According to the above configuration, there is an effect that the component can be easily manufactured at a low cost without requiring a new component such as a sensor.

In the bearing device according to the present invention, a voltage is applied to the ER fluid in synchronization with the motor start command, and the motor is started by applying a voltage to the ER fluid by the motor start delay means.
The motor stop command is characterized in that the voltage applied to the ER fluid is turned off after the motor is stopped by the delay means.

According to the above configuration, the viscosity of the ER fluid becomes high before the shaft rotates, that is, before the motor rotates at the time of start-up, and the ER fluid holds the shaft. By turning off the shaft, the shaft and the bearing are started and stopped in a non-contact state, and there is an effect that the bearing is not worn, accuracy is maintained, and reliability is improved.

In a twelfth aspect of the present invention, the insulator is made of resin or ceramics, and the resin or ceramics is used alone or in combination with a metal.

According to the above configuration, there is an effect that it can be manufactured at low cost and with high accuracy.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail.

(Embodiment 1) FIG. 1 is a sectional view of a bearing using the ER fluid of the present invention, and FIG. 2 is an enlarged view of an upper portion of the bearing of FIG. 1 and will be described with reference to FIGS. The shaft 2 is rotatably supported by a bearing 3, and an ER fluid and a mechanism for holding and driving the ER fluid are disposed at both axial ends of the bearing 3, and a bearing body 1 is provided.
Is composed. In the figure, a conductive material for applying a voltage to the ER fluid is provided between a spacer 7 as a first insulator and a spacer 8 as a second insulator made of an electrically insulating material above the bearing 3. An electrode 9 made of a conductive material is sandwiched between the U-shaped space formed by the spacers 7 and 8 and the electrode 9 and the shaft 2 and the ER fluid 10 is filled. On the other hand, also on the lower side of the bearing 3, similarly to the upper side, the electrode 13 is interposed between the spacer 11 of the first insulator and the spacer 12 of the second insulator.
An ER fluid 10 is filled in a space formed by the electrodes 1, 12 and the electrode 13 and the shaft 2.

The bearing 3, the upper spacers 7 and 8, and the lower spacers 11 and 12 are inserted and fixed in a sleeve 4, and the sleeve 4 is supported and fixed on a base plate 21 of a motor (not shown). Upper spacers 7 and 8
And lower spacers 11 and 12, respectively, are support plates 6 and 5, respectively.
Is fixed in the thrust direction. The support plate 5 receives the shaft 2 having a spherical lower portion, and also serves to position the shaft in the downward direction.

A DC power supply 20 is provided outside the bearing, and the pole on one side has a slip ring 14 provided on the shaft 2 and a lead wire 1.
7 are connected. The other pole is connected to the lead wire 19 and the electrode 9, and to the lead wire 18 and the electrode 13. The lead wire 19 is provided in the hole 1 provided in the support plate 6 and the spacer 8.
The lead wire 18 is connected to the electrode 13 through the support plate 5 and the hole 16 provided in the spacer 12. The ER fluid 10 is configured to be applied with a voltage by the shaft 2 and the electrodes 9 and 13.

The spacers 7 and 8 have a structure shown in FIG.
There is a clearance L as shown by. If the clearance is minus (the inner diameter of the spacer is smaller than the inner diameter of the bearing), the sliding resistance will increase due to the contact between the shaft and the spacer, and wear powder will enter the bearing sliding surface, causing the bearing life and mixing into the ER fluid. Clearance is 0 due to adverse effects
As described above, it is necessary to maintain a non-contact state. On the other hand, if the clearance L is too large, foreign matter such as dust enters from the outside or the ER fluid leaks. Therefore, it is preferable to make the clearance L as small as possible while considering the mechanical accuracy. Specifically, among the plain bearings, a typical oil-impregnated bearing has a 50 μm, which is about the same as the clearance between the shaft and the bearing.
m or less, more preferably 30 μm or less, which is about the same as precision instrument use, and more preferably 10 μm or less, which is about the same as high precision equipment use.

The ER fluid used in the present invention is a fluid whose viscosity changes instantaneously and largely reversibly when an electric field is applied, and is a dispersion system in which electrically polarizable particles are dispersed in insulating oil. , And homogeneous systems. As a dispersion system, inorganic particles such as silica or zeolite containing ion-polarizable water, acid, alkali, or organic electrolyte, or organic particles such as ion-exchange resin or cellulose, and containing water do not cause ionic polarization but produce electronic polarization rather than ionic polarization. Semiconductor particles such as carbon, polyanine, and metal phthalocyanine, metal particles and conductive polymer particles coated with an insulating coating on the surface, and other particles made of a material having anisotropic conductivity or nonlinear non-optical properties. It has a high electric breakdown strength and is chemically stable, and particles are stably dispersed in insulating oil. As the insulating oil, for example, silicon-based oil, mineral oil, diphenyl chloride and the like can be used. On the other hand, as a homogeneous system,
A substance or a solution having particle size anisotropy, ferroelectricity, high dipole efficiency, and the like can be mentioned, and a liquid crystal is preferable.

FIG. 3 is a diagram for explaining the principle of the bearing of the present invention. The ER fluid 10 is filled between the electrodes 44 arranged on the left and right. In a state where the voltage is off, as shown in FIG. 3A, the electrically polarizable particles 36 in the fluid 35 are in a state of being dispersed at random, but in a state where a voltage is applied as shown in FIG. The particles 36 are polarized by the electric field generated between the electrodes 44, and the particles are attracted to each other and are arranged on the chain between the electrodes 44. The particle chains obstruct the flow of the fluid 35, and the fluid viscosity increases apparently. As described above, by utilizing the fact that the fluid viscosity is increased by applying a voltage, it is possible to change the magnitude of the load received by the fluid and to control the amount of load received by controlling the voltage. Become.

FIG. 3 shows a method of receiving a load with a fluid.
When the electrodes 44 are arranged in parallel with the axis as shown in FIG. 1B, that is, by providing one electrode on the axis side and providing the other in the radial direction as in FIG. 1, the force in the radial direction of the axis ( R) in FIG. 3B is received.

To receive a radial load, the electrodes need to be fixed against radial forces. In the present invention, the spacers 7 and 11 are substantially L-shaped, receive the electrode 9 or 13 at the step, and receive the outer shape of the spacers 7 and 11 by the inner shape of the sleeve 4 to easily and strongly receive the load. be able to.

The spacers 7, 11, 8 and 12 can be easily and accurately manufactured by using an electrically insulating material such as resin or ceramic. In addition, a coating can be formed with a resin material on the surface of a metal material such as an iron material which is generally widely used, so that an insulator can be formed.

FIG. 10 is a diagram for explaining the control of the voltage of the ER fluid.
The R fluid controller 30 is turned on in synchronization with the command, turns on the ER fluid power supply 20, and increases the viscosity of the ER fluid. On the other hand, the motor controller 29 turns on and starts the motor 28 with a delay in response to the command. In response to the motor stop command 31, the motor controller 29 immediately stops the motor, but the ER fluid controller 30 delays the command and turns off the ER fluid power supply 20 after the motor 28 stops. I do. By doing so, starting and stopping can be performed in a state where the shaft is not in contact with the bearing.

Since the viscosity of the ER fluid changes depending on the voltage, if the voltage is changed according to the number of rotations of the motor, the condition of the bearing can be changed according to the condition of the motor. A motor that uses a permanent magnet for the field generates a back electromotive voltage according to the number of rotations. By changing the voltage applied to the ER fluid according to the back electromotive voltage, the state of the bearings according to the rotation of the motor Can be changed. The back electromotive voltage of the motor is detected by the motor controller 29, and a voltage signal proportional thereto is sent to the ER fluid controller 30, and the ER fluid controller 30 controls the viscosity of the ER fluid by controlling the voltage value of the power supply 20 according to the signal. it can.

Next, an example of application of the bearing having the above configuration to a motor will be described. FIG. 9 is a cross-sectional view of a spindle motor for CD-ROM. A turntable 27 is mounted on the tip of the shaft 2, and the bearing 1 is fixed to a motor mounting base plate 21. Outside the sleeve 4, there is a stator core 23, on which an exciting coil 24 is wound. The back yoke 26 is attached to the shaft 2, and the permanent magnet 15 is attached so as to face the stator core 23. The lead wire 18 drawn out from the electrode on the lower side of the bearing passes above the base plate 21 through a hole 22 formed in the base plate 21 and is on the base plate 21 together with the lead wire 19 drawn out from the electrode on the upper side of the bearing. Are connected by the solder 34 of the wiring board 32. Similarly, the lead wire 17 drawn from the slip ring is also connected to the substrate by the solder 33.

By applying a voltage to the ER fluid 10 and apparently increasing the viscosity of the ER fluid, the rigidity of the bearing body 1 in the radial direction is increased and the bearing body 1 can withstand a large load.
In addition, since there is no clearance between the ER fluid and the shaft, the rotation is stable and high-precision rotation is obtained, and the shaft is always supported so that vibration can be reduced. Further, since the ER fluid is located at both ends of the bearing, the lubricating oil of the bearing is shielded by the ER fluid, thereby preventing the lubricating oil from scattering. In addition, since the shaft and the bearing can be kept in a non-contact state when the motor is stopped and started, wear can be prevented, and high accuracy and long life can be achieved.

The bearing used in the embodiment of the present invention can be applied to any of a metal bearing and a dynamic pressure bearing, and when combined with a metal bearing, the improvement of the rigidity of the bearing, the high precision rotation, and the long life are great advantages. . Also, in combination with a dynamic pressure bearing,
It is possible to reduce the sealing property and the metal contact between the shaft and the bearing at the time of starting and stopping.

In this embodiment, the ER fluid is provided at both ends of the bearing. However, it goes without saying that only one of the two ends may be used.

(Embodiment 2) FIG. 4 is a sectional view of a main part of a bearing showing a second embodiment, and FIG. 5 is a perspective view of an insulator and an electrode. It was done. The arrangement of the electrodes of the present invention is configured in the axial direction, and E
An R fluid is contained therein, and is configured to receive the force in the S direction of FIG. 3B described in the principle explanation of the first embodiment.

The details will be described below. FIG. 4 is an enlarged view of the upper side of the bearing portion. As shown in FIG. 4, an electrode 44 is formed on one surface of a spacer 7 made of a first insulator above the bearing 3, and further above the same. The electrode 44 is formed on one surface of the spacer 8 made of the second insulator by a simple method, the electrodes 44 are opposed to each other, the third insulator 45 is interposed between the electrodes 44, and the support plate 6 is interposed therebetween. It is fixed to the sleeve 4. Then, the electrode 44 on the spacer 7, the electrode 44 on the spacer 8, the third insulator 45,
The space surrounded by the axis 2 is filled with the ER fluid 10.

Next, the insulator and the electrode will be described with reference to FIG. A ring-shaped electrode 44 is formed on one surface of the spacer 7 made of an insulating material. A projection 53 is provided on a part of the outer periphery of the spacer 7. An electrode pad 51 for connecting a lead wire is provided on the projection 53, and the electrode 4
4 and the electrode pad 51 are connected by an electrode lead 52. Similarly, the spacer 8 also has an electrode 44, an electrode pad 51, and an electrode lead 52 formed on the spacer 8. The electrode pad 51 on the spacer 7 and the power supply 20 are connected by a lead 19, and the electrode pad 51 on the spacer 8 and the power supply 20 are connected by a lead 17.

The insulator and the electrode can be obtained by etching a pattern on a general circuit board in which a copper foil is formed on a resin board into a desired shape. It can also be obtained by attaching a film or the like.

Since the projections 53 are provided on a part of the outer shape of the spacers 7 and 8, the projections 53 are aligned with the cuts (not shown) provided on the sleeve 4, and the outer diameters of the spacers 7 and 8 are adjusted. By assembling the inner diameter of 4 into the guide, assembly can be easily performed.

As described above, the upper side of the bearing 3 has been described, but the lower side also has a similar configuration and method. In the case of such a configuration, it is possible to receive a force in the S direction shown in FIG.

(Embodiment 3) FIG. 6 is a view for explaining a new electrode structure, and is a sectional view when the bearing is viewed from the axial direction. An ER fluid 1 is provided between the shaft 2 and the insulator 45.
0 is satisfied. On the inner periphery of the insulator 45, a plus electrode 40 and a minus electrode 41 are arranged on the circumference along the axial direction.
They are arranged in pairs. By applying a voltage to the electrodes 40, 41, the viscosity of the ER fluid 10 increases and supports the shaft 2. By continuously arranging the electrode 40 and the electrode 41 along the circumference, the viscosity of the ER fluid becomes uniform around the circumference and
Supported by the center of the bearing.

The shaft is supported by the center of the bearing even when the shaft is stationary, that is, when the shaft does not rotate, but the same applies when the shaft rotates. This will be described in detail. Due to the rotation of the shaft 2, a flow 42 is generated in the ER fluid along the rotation of the shaft 2, and the ER fluid turns the shaft 2. Since the swirling flow 42 flows so as to uniformly apply a force to the outer peripheral portion of the shaft 2, the swirling flow 42 functions to automatically hold the center of the swirling flow, and serves as a bearing that automatically aligns the shaft.

FIG. 7 is a perspective view showing an example of the electrode structure of the present invention. A plurality of electrodes 44 extending from the upper surface to the lower surface are formed on the inner diameter of the insulator 45. Here, the direction from the upper surface to the lower surface is the axial direction of the shaft. Electrode 4
An electrode pad 46 is formed at one end of 4 and an electrode pad 47 is formed at the other end in the same manner to facilitate connection with a lead wire. The electrode 44 is obtained by continuously forming a metal having a small electric resistivity, for example, copper into a rectangular wave shape as shown in FIG. . Further, it can be obtained similarly by etching the copper foil bonded to the resin in the same manner as in Example 2.

The same effect as in the first and second embodiments can be obtained by disposing the insulator 45 on the both end surfaces of the bearing 3 as described in the second embodiment with the above-described electrodes 44 formed thereon.

In this embodiment, the number of electrodes has been described as four. However, the number of electrodes is not limited to this, and may be any number as desired.

[0056]

According to the present invention, by providing a bearing made of ER fluid on the end face of the bearing, the bearing rigidity is improved, high load resistance and vibration resistance are achieved, and the shaft and the bearing are in a non-contact state. Shaft and bearing wear is reduced. In addition, since lubricating oil is prevented from scattering from the bearing, high accuracy and high reliability can be obtained.

Further, there is an effect that the productivity is excellent and the cost is low with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a sectional view of a bearing.

FIG. 2 is an enlarged view of an ER fluid holding portion.

FIG. 3 is a diagram illustrating the principle of a bearing.

FIG. 4 is a sectional view of a main part of the bearing.

FIG. 5 is a perspective view of an insulator and electrodes.

FIG. 6 is a diagram for explaining the principle of a bearing.

FIG. 7 is a perspective view showing an example of an electrode structure.

FIG. 8 is a development view of an electrode.

FIG. 9 is a sectional view of a spindle motor.

FIG. 10 is a view for explaining control of the voltage of the ER fluid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bearing body 2 ... Shaft 3 ... Bearing 4 ... Sleeve 5, 6 ... Support plate 7, 8, 11, 12 ... Spacer 9, 13 ... Electrode 10 ... -Electro-rheological fluid 14-Slip ring 15, 16, 22-Hole 17, 18, 19-Lead wire 20-Power supply 21-Base plate 23-Stator core 24-Coil 25 ... permanent magnet 26 ... back yoke 27 ... turntable 28 ... motor 29 ... motor controller 30 ... power supply controller 32 ... board 33, 34 ... solder 35 ... Fluid 36 ・ ・ ・ Electrically polarizable particles 40,41,44 ・ ・ ・ Electrode 45 ・ ・ ・ Insulator 46,47 ・ ・ ・ Electrode pad 48,49 ・ ・ ・ Bend line

Claims (12)

[Claims] A shaft, a bearing that supports the shaft in rotation, an electrorheological fluid whose viscosity changes when a voltage is applied thereto,
It has an electrode and a power supply for applying a voltage to this electrorheological fluid,
A bearing device wherein an electrorheological fluid is arranged in an axial direction near a bearing. A shaft, a bearing for supporting the shaft in rotation, first and second electrical insulators provided on end faces of the bearing, and a conductor sandwiched between the first and second insulators. An electrode, an electrorheological fluid whose viscosity is changed by applying a voltage between a shaft and the first and second insulators and in a space surrounded by the electrode, and a power supply for applying a voltage between the shaft and the electrode A bearing device comprising: 3. A shaft, a bearing for supporting the shaft in rotation, first, second and third electrical insulators provided on the end face of the bearing, and sandwiched between the first and third electrical insulators. The first conductor
, A second electrode composed of a conductor sandwiched between the second and third insulators, and a shaft filled with a voltage filled in a space surrounded by the third insulator and the first and second electrodes. An electrorheological fluid whose viscosity changes by applying a first electrode and a second electrode.
A power supply for applying a voltage between the electrodes. 4. A shaft, a bearing for supporting the shaft in rotation, first, second, and third electrical insulators provided on end faces of the bearing, and sandwiched between the first and second electrical insulators. An electrode composed of a plurality of conductors extending between the third electrical insulator and the shaft and extending in the axial direction, and applying a voltage filled in a space surrounded by the shaft and the third insulator. A bearing device, comprising: an electrorheological fluid whose viscosity changes by the change, and a power supply for applying a voltage between a plurality of electrodes. 5. The bearing device according to claim 1, wherein the bearing is a plain bearing. 6. The bearing according to claim 1, wherein an insulator, an electrode and an electrorheological fluid are provided on both end faces of the bearing.
The bearing device as described. 7. A conductive metal foil bonded to an insulator made of a resin is formed in a desired shape, and the insulator is made of a first insulator,
A conductive metal foil as a first electrode or an insulator as a second insulator,
The bearing device according to claim 3, wherein the conductive metal foil is used as the second electrode. 8. The bearing device according to claim 4, wherein a plurality of electrodes extending in the axial direction are formed in a desired shape on the third insulator. 9. A bearing device according to claim 1, further comprising means for detecting a rotational speed of the shaft, wherein the voltage applied to the electrorheological fluid is controlled in accordance with a change in the state of the bearing device. . 10. The bearing device according to claim 9, wherein the rotation speed of the shaft is detected using a back electromotive voltage of a permanent magnet for a field of a motor. 11. A voltage is applied to the electrorheological fluid in synchronization with a motor start command, a motor is started after a voltage is applied to the electrorheological fluid by motor start delay means, and a motor stop command is applied after the motor is stopped by the delay means. 5. The bearing device according to claim 1, wherein the voltage applied to the viscous fluid is turned off. 12. The bearing device according to claim 1, wherein the insulator is made of resin or ceramics, and the resin or ceramics is used alone or in combination with a metal.