JP2003028236A - Damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a constant damping force by imparting a viscous resistance with magnets 12 to a magnetorheological fluid 5 flowing in a viscous fluid passage 8 according to movement of a movable part 10 in a damper A for damping movement of the movable part 10 to position the magnetorheological fluid 5 of an overall passage width of the viscous fluid passage 8 in a uniform magnetic field to keep the viscous resistance constant by the magnets 12 on the magnetorheological fluid 5 via simple control, and suppress dispersion in damping force. SOLUTION: The pair of magnets 12 are opposed with the viscous fluid passage 8 in between around the viscous fluid passage 8. Lines of magnetic force between the magnets 12 opposed with the viscous fluid passage 8 in between are applied as the uniform magnetic field to the magnetorheological fluid 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping device for damping a movement of a movable portion by a damping force by viscous resistance of a magnetic rheological fluid (MRF) generated by a magnet.

[0002]

2. Description of the Related Art This type of magnetorheological fluid is a composite material in which an extremely fine ferromagnetic material is dispersed in a liquid, and the liquid behaves as if it has a ferromagnetic material.
As a damping device using this magnetic viscous fluid, conventionally, (1) the magnetic viscous fluid is filled between the walls that relatively move according to the movement of the movable part, and the magnetic viscous fluid is subjected to shear resistance by magnetic force. It is known that the movement of the movable part is attenuated by adding the.

In addition to the above, (2) a viscous fluid passage through which a magnetorheological fluid flows according to the movement of the movable portion is provided, and a viscous resistance is imparted to the magnetorheological fluid in the viscous fluid passage by a magnet to move the movable portion. It is also known that the movement of the part is attenuated.

[0004]

By the way, although various structures have been proposed for the structure of the above-mentioned conventional example (2), in each of them, the actual behavior of the magnetorheological fluid by the magnet is sufficiently examined. However, the characteristic change of the magnetorheological fluid shown in the literature etc. is simply used, and there are the following problems.

That is, in this conventional damping device, the entire passage width of the magnetorheological fluid in the viscous fluid passage is not located in the uniform magnetic field, and the viscous resistance of the magnet of the magnetorheological fluid is changed to reduce the damping force. Vary. Then, in order to obtain a constant damping force, the magnetic force with respect to the magnetorheological fluid may be controlled, but the control is inevitably complicated.

Further, since the region of the viscous fluid passage that applies the magnetic force to the magnetic viscous fluid is narrow, it is difficult to obtain a large damping force. The damping force can be increased by increasing the magnetic force of the magnet, but in that case, there is a problem that the cost is increased.

The present invention has been made in view of the above points, and an object thereof is to devise an arrangement configuration of magnets that exert a magnetic force on the magnetic viscous fluid so that the magnetic viscous fluid in the viscous fluid passage is By positioning the magnet in a uniform magnetic field over the entire width and keeping the viscous resistance of the magnet of the magnetorheological fluid constant by a simple control to suppress variations in damping force, a constant damping force can be obtained as a damping device. To do.

Another object of the present invention is to similarly devise the arrangement and arrangement of the magnets so as to expand the region of the viscous fluid passage to which the magnetic force is applied, without increasing the cost. It is to obtain a large damping force.

[0009]

In order to achieve the above object, in the present invention, a pair of magnets are arranged to face each other around a viscous fluid passage, or a plurality of magnets are arranged in parallel on a side of the viscous fluid passage. I decided to do it.

Specifically, according to the first aspect of the invention, a viscous fluid passage through which the magnetorheological fluid flows according to the movement of the movable portion is provided, and the magnet gives viscous resistance to the magnetorheological fluid in the viscous fluid passage. As a damping device adapted to damp the movement of the movable part, a magnet paired around the viscous fluid passage is arranged to face each other with the viscous fluid passage sandwiched therebetween. is there.

According to the above construction, when the movable part moves, the magneto-rheological fluid flows in the viscous fluid passage along with the movement, and the magnet gives viscous resistance to the magnetorheological fluid in the viscous fluid passage. , The movement of the movable part is damped.

At this time, since the magnets are arranged in a pair around the viscous fluid passage so as to face each other with the viscous fluid passage sandwiched therebetween, the lines of magnetic force (magnetic flux) between the facing pair of magnets are A uniform magnetic field acts on the magneto-rheological fluid over the entire width of the passage located between the magnets, which reduces the variation in the damping force of the damping device and obtains a constant damping force.

On the other hand, in the invention of claim 2, as a damping device similar to the invention of claim 1, a plurality of magnets are arranged side by side along the viscous fluid passage alongside the viscous fluid passage. To do. As a result, a plurality of magnets arranged along the viscous fluid passage give a magnetic force to the magnetorheological fluid in the viscous fluid passage in a wide area, and the damping force of the damping device can be increased accordingly. .

According to the invention of claim 3, the above-mentioned claim 2 is used.
In the damping device according to the invention, the magnets are arranged opposite to the viscous fluid passage of at least one of the plurality of magnets arranged along the viscous fluid passage so as to face each other with the viscous fluid passage interposed therebetween. Be present. In this case, the effects of the inventions of claims 1 and 2 are obtained synergistically, and the damping force of the damping device can be increased and made constant.

Further, in the invention of claim 4, the opposing magnetic poles on the viscous fluid passage side of both magnets which face each other across the viscous fluid passage are different from each other. As a result, the magnetic field for the magnetorheological fluid in the viscous fluid passage becomes more uniform, and a constant damping force can be obtained more stably.

According to the fifth aspect of the present invention, the magnetic poles on the viscous fluid passage side of the plurality of magnets arranged along the viscous fluid passage are alternately different from each other. With this,
The damping force of the damping device can be stably increased.

According to the invention of claim 6, the viscous fluid passage is provided in the pipe portion. According to the invention of claim 7,
The viscous fluid passages are provided between the opposing side walls facing each other with a space therebetween. These inventions provide the desired viscous fluid path for placement of the magnet.

In the invention of claim 8, the magnet is an electromagnet. This makes it possible to easily control the damping force.

According to the ninth aspect of the invention, the magnets are provided at both ends of the core of the electromagnet. As a result, a pair of magnets having different magnetic poles can be easily obtained, and the damping force can be easily controlled.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 4 shows a damping device A according to a first embodiment of the present invention, where 1 is a cylinder and 2 is a piston which is reciprocally fitted in the cylinder 1. ,
This piston 2 is a rod 3 that penetrates one end of the cylinder 1.
Is connected to the movable part 10 by means of which the piston 2 reciprocates in the cylinder 1 when the movable part 10 moves in the left-right direction in the drawing.

On the other side of the cylinder 1, there is a viscous fluid chamber 4
Is formed by a piston 2 and the viscous fluid chamber 4 is filled with a magnetic viscous fluid 5 in which an extremely fine ferromagnetic material is dispersed in a liquid. A pipe portion 7 made of a non-magnetic material is integrally connected to the other end of the cylinder 1, and a viscous fluid passage 8 that is in constant communication with the viscous fluid chamber 4 in the cylinder 1 is formed in the pipe portion 7. The magnetorheological fluid 5 flows in the viscous fluid passage 8 according to the movement of the movable portion 10.

Further, a pair of magnets 12, 12 are arranged around the viscous fluid passage 8 (tube portion 7), and the magnets 12, 12 make the magnetorheological fluid 5 in the viscous fluid passage 8 viscous. By applying resistance, the movement of the movable portion 10 is attenuated.

As shown in FIG. 1, the pair of magnets 12, 12 are arranged around the viscous fluid passage 8 so as to face each other with the viscous fluid passage 8 sandwiched therebetween. Also, a pair of magnets 12, 12 facing each other with the viscous fluid passage 8 in between.
The magnetic pole on one side (the one on the lower side in FIG. 1) on the viscous fluid passage 8 side is, for example, the N pole, and the other (the one on the upper side).
The magnetic poles on the viscous fluid passage 8 side are set to be, for example, S poles, and the opposing magnetic poles of both magnets 12 and 12 are different from each other.

Specifically, as shown in FIG. 2, the pair of magnets 12 and 12 are constructed as a part of the electromagnet 13. That is, the electromagnet 13 includes a substantially U-shaped core 14 (iron core) made of soft iron, steel, or the like, and a coil 15 wound around an intermediate portion of the core 14, and both ends of the core 14 are located between them. The core portion 14 is arranged so as to sandwich the tube portion 7, and by supplying a direct current to the coil 15,
Both ends of each of the magnets are made a pair of magnets 12, 12.

In addition to providing the viscous fluid passage 8 in the pipe portion 7 as described above, as shown in FIG. 3, the viscous fluid passage 8 is provided between the opposed side walls 17 facing each other with a space therebetween. It is also possible to provide the fluid 5 in a liquid-tight state so that the fluid 5 does not leak out, and to arrange the opposing side walls 17 and 17 between both ends (magnets 12 and 12) of the core 14 in the electromagnet 13. . Further, FIG. 5 shows a structure in which one magnet 12 is arranged laterally of the viscous fluid passage 8 for reference.

Therefore, in the above embodiment, when the movable part 10 moves leftward or rightward in FIG. 4, the piston 2 moves in the cylinder 1 in accordance with the movement, and the magnetic viscous fluid in the viscous fluid chamber 4 is moved. The fluid 5 flows so as to come and go through the viscous fluid passage 8 in the pipe portion 7. Then, a direct current is applied to the coil 15 of the electromagnet 13 so that the end of the core 14 is moved to the magnet 12,
The magnets 12 and 12 give viscous resistance to the magnetorheological fluid 5 in the viscous fluid passage 8, and the movement of the movable portion 10 is attenuated.

At this time, since the magnets 12 and 12 are arranged opposite to each other with the viscous fluid passage 8 sandwiched therebetween so as to sandwich the viscous fluid passage 8 therebetween, as shown in FIG. When one magnet 12 is arranged on the side of, the magnetorheological fluid 5 in the entire passage width is not located in a uniform magnetic field, whereas the line of magnetic force between the opposing magnets 12, 12 is between the magnets 12, 12. Magnetorheological fluid 5 of the entire passage width (this passage width is the width in the facing direction of the magnets 12, 12) located at
Acts as a uniform magnetic field. Moreover, since the facing magnetic poles on the viscous fluid passage 8 side of the magnets 12, 12 facing each other across the viscous fluid passage 8 are different from each other, the magnetic field of the viscous fluid passage 8 with respect to the magnetorheological fluid 5 becomes more uniform. As a result, the variation of the damping force of the damping device A is reduced, and a constant damping force can be obtained.

Then, in this way, the coil 1 of the electromagnet 13 is
Since a constant damping force can be obtained by applying a constant control current to 5, the vibration can be controlled by controlling each factor (spring constant, damping constant, mass, etc.) involved in the vibration with simple control. It is possible to realize a semi-active control type damping device that suppresses vibration.

Since the magnets 12 and 12 facing each other with the viscous fluid passage 8 in between are composed of electromagnets 13,
The damping force can be changed only by changing the current supplied to the coil 15, and the damping force can be easily controlled. Moreover, a configuration in which the pair of magnets 12 and 12 are arranged to face each other around the viscous fluid passage 8 can be easily obtained.

(Embodiment 2) FIGS. 6 to 8 show Embodiment 2 of the present invention (note that the same parts as those in FIGS. 1 to 4 are denoted by the same reference numerals and detailed description thereof will be omitted). In the first embodiment, the magnets 12 and 12 are arranged to face each other with the viscous fluid passage 8 in between, but the magnets 12 and 12 are arranged side by side along the viscous fluid passage 8.

That is, in this embodiment, FIG.
As shown in FIG. 1, a pair of magnets 12, 12 are provided on the side of the viscous fluid passage 8, more specifically, on the side of the pipe portion 7 having the viscous fluid passage 8.
12 are arranged side by side along the viscous fluid passage 8. The pair of magnets 12, 12 arranged along the viscous fluid passage 8 have different magnetic poles on the viscous fluid passage 8 side. still,
The two magnets 12, 12 may be arranged in contact with each other, or may be arranged in a separated state with a gap.

Then, as shown in FIG. 7, a pair of magnets 1
Reference numerals 2 and 12 are composed of both ends of the core 14 in the electromagnet 13 including the substantially U-shaped core 14 and the coil 15 wound around the intermediate portion thereof, and both ends of the core 14 are the outer circumference of the pipe portion 7. The magnets are arranged on the surface in a line along the lengthwise direction, and a pair of magnets 12 and 12 are formed at both ends of the core 14 by supplying a direct current to the coil 15.

Also in this second embodiment, as shown in FIG. 8, the opposing side walls 17, which are opposed to each other with a space therebetween,
The viscous fluid passage 8 is provided between 17 in a liquid-tight state so that the internal magnetic viscous fluid 5 does not leak out, and the pair of magnets 12 and 12 at both ends of the core 14 of the electromagnet 13 are connected to one of the opposing side walls 1.
It is also possible to arrange them side by side along 7.

Therefore, in this embodiment, the pair of magnets 12 and 12 arranged along the viscous fluid passage 8 causes
Since the magnetic force is applied to the magnetorheological fluid 5 in the viscous fluid passage 8 in a wide area, the damping force of the damping device A can be increased.

In addition, 1s arranged along the viscous fluid passage 8
Since the magnetic poles of the pair of magnets 12, 12 on the viscous fluid passage 8 side are different from each other, the damping force of the damping device A can be stably increased.

When the damping device A is used as a semi-active control type vibration damping device, it is not necessary to dispose one strong magnet 12 having a large magnetic force (see FIG. 5).
), Even if the magnetic force of each magnet 12 is weak, both magnets 12,
A strong damping force can be obtained by the magnetic force generated by both of the magnetic fields 12, and the cost of the power supply for obtaining the magnetic force can be reduced.

(Other Embodiments) The present invention is not limited to the above embodiments, but includes various other embodiments. For example, in the above-described first embodiment, the magnets 12, 12 facing each other with the viscous fluid passage 8 sandwiched therebetween form one pair, but a plurality of pairs of magnets 12 and 1 of two or more pairs.
, 2 may be arranged so that each pair of magnets 12 and 12 face each other with the viscous fluid passage 8 in between,
The same effects as those of the first embodiment can be obtained (Example 1).

Further, in this case, the facing direction of each pair of magnets 12, 12 is arranged so as to be offset in the circumferential direction from the direction of the viscous fluid passage 8 with respect to that of the other pair of magnets 12, 12. You can also

On the other hand, in the second embodiment, the pair of magnets 1
2 and 12 are arranged along the viscous fluid passage 8, but 3
One or more magnets 12, 12, ... May be arranged along the viscous fluid passage 8, and the same effect can be obtained.

In this case, at least one of the plurality of magnets 12, 12, ... Arranged along the viscous fluid passage 8 has a magnet 12 on the opposite side of the viscous fluid passage 8 from the magnet 12. May be arranged to face each other (the magnets 12, 12, ... Are arranged on the side opposite to the viscous fluid passage 8 with respect to all of the plurality of magnets 12, 12, .. In this way, the effects of Embodiments 1 and 2 can be obtained synergistically, and the damping force of the damping device A can be increased and made constant.

Further, in each of the above embodiments, the electromagnet 13 is used.
The magnets 12 and 12 are formed at both ends of the core 14 of
Each magnet 12 may be individually configured by an electromagnet,
The damping force can be easily controlled.

[0042]

EXAMPLES Next, specific examples will be described. FIG. 9 shows a magnetic viscous characteristic test apparatus, which has a base 21. On this base 21, front brackets 22, 2 facing in the left-right direction (left-right direction in FIG. 9) are provided.
2 and the rear brackets 23, 23 are erected at an interval in the front-rear direction (vertical direction in FIG. 9),
A guide rod 24 that extends in the left-right direction is bridged between the two and 22. On the other hand, a screw shaft 25 extending in the left-right direction is rotatably supported between the rear brackets 23, 23,
The left end of the screw shaft 25 extends to the left through the left rear bracket 23, and is rotationally and integrally driven by a coupler 27 to an output shaft 26a of an electric motor 26 installed on the base 21. . And the rear bracket 2
One end of a pressing plate 28 extending in the front-rear direction is screwed into the screw shaft 25 between the third and the third through a screw hole 28a, and the other end of the pressing plate 28 is slidable on the guide rod 24 through a guide hole 28b. It is inserted through and supported by the motor 26, and the pressing plate 28 is moved in the left-right direction while being guided by the guide rod 24 by the rotation of the screw shaft 25 by the motor 26.

Further, the front and rear brackets 22, 23 on the right side
A syringe 29 having a center line in the left-right direction is attached and fixed on the base 21 between them, and the syringe 29 has a pressurizing chamber defined by a piston therein (neither is shown).
Have. The piston is connected to a piston rod 30 that projects from the left end of the syringe 29 and expands and contracts with respect to the syringe 29. The left end of the piston rod 30 is fixedly connected to the front-rear intermediate portion of the pressing plate 28. In addition, a nozzle 31 as a tube portion is provided at the right end of the syringe 29.
And a viscous fluid passage (not shown) communicating with the pressurizing chamber in the syringe 29 is formed in the nozzle 31, and the viscous fluid passage in the pressurizing chamber or the nozzle 31 is filled with the magnetic viscous fluid. Has been done.

Further, the magnet 12 is arranged around the nozzle 31, and when the pressing plate 28 is moved to the right side, the magnetorheological fluid in the pressurizing chamber in the syringe 29 is moved to the nozzle 31.
The viscous damping characteristics were tested by pushing out at a constant speed into the viscous fluid passage and measuring the reaction force, that is, the damping force, as a pressure (unit: MPa) until a certain measurement time (80 seconds) passed. .

The arrangement of the magnets 12 is shown in FIG.
As shown in (a), one magnet 12 is arranged so that its magnetic pole surface is orthogonal to the viscous fluid passage in the nozzle 31 (see FIG. 5), and as shown in FIG. A facing arrangement in which the pair of magnets 12, 12 are arranged so as to face each other around the nozzle 31 with a viscous fluid passage interposed therebetween (see FIG. 1),
As shown in FIG. 10C, there are three types, that is, a pair of magnets 12, 12 arranged in parallel around the nozzle 31 along the viscous fluid passage (see FIG. 6).

In addition to this, the magnet 1 is provided around the nozzle 31.
The viscous damping characteristics were tested in the same manner even when 2 was not arranged (without applying magnetic force).

The above test results are shown in FIG. Considering this result, the three types of the standard arrangement in which the magnets 12 are arranged around the nozzle 31, the opposed arrangement, and the parallel arrangement are all compared to those without the magnetic force without the magnets 12 around the nozzle 31. The reaction force is as high as about twice or more, and viscous resistance is given to the magnetic viscous fluid by the magnetic force of the magnet 12.

The magnet 12 is arranged around the nozzle 31.
Comparing the types, the magnitude of the reaction force (damping force) varies in the standard arrangement during the measurement time, whereas the reaction force in the opposing arrangement has a smooth value with little variation.

That is, since one magnet 12 is used in the standard arrangement, the magnetorheological fluid is not located in a uniform magnetic field, whereas in the opposing arrangement, the magnetorheological fluid is located between the magnets 12, 12. Since the magnetic force lines act as a uniform magnetic field on the magneto-rheological fluid, variations in reaction force are reduced.

Further, in the parallel arrangement, a reaction force (damping force) larger than that in the reference arrangement was obtained. This is because in the parallel arrangement, the magnetic force can be applied in a wider area than in the reference arrangement.

From the above, by arranging the pair of magnets 12, 12 with the viscous fluid passage interposed therebetween as in the present invention, the variation of the damping force can be reduced, while
It can be seen that the damping force can be increased by arranging the plurality of magnets 12, 12 along the viscous fluid passage.

[0052]

As described above, according to the first aspect of the present invention, the viscous resistance is imparted by the magnet to the magnetorheological fluid flowing in the viscous fluid passage in response to the movement of the movable portion to attenuate the movement of the movable portion. In this case, by arranging magnets that are paired around the viscous fluid passage so as to face each other with the viscous fluid passage sandwiched between them, the lines of magnetic force between the pair of magnets that face each other with the viscous fluid passage sandwiched The magnetic viscous fluid over the entire passage width can be made to act as a uniform magnetic field, and the damping force of the damping device can be made a constant damping force with small variations.

According to the second aspect of the present invention, a plurality of magnets are arranged side by side along the viscous fluid passage so that the magnetic viscous fluid in the viscous fluid passage is given a magnetic force in a wide area. As a result, the damping force of the damping device can be increased.

According to the invention of claim 3, in the damping device of the invention of claim 2, at least one magnet of the plurality of magnets arranged along the viscous fluid passage is provided on the side opposite to the viscous fluid passage. By arranging the two in opposition to each other with the viscous fluid passage interposed therebetween, the damping force of the damping device can be increased and made constant.

According to the fourth aspect of the present invention, the opposing magnetic poles on the viscous fluid passage side of both magnets facing each other across the viscous fluid passage are made different from each other, so that the magnetic field for the magnetorheological fluid in the viscous fluid passage is changed. Further uniforming, a constant damping force can be obtained more stably.

According to the invention of claim 5, the magnetic poles on the viscous fluid passage side of the plurality of magnets arranged along the viscous fluid passage are alternately different from each other, so that the damping force of the damping device is stabilized. Can be increased.

In the sixth aspect of the invention, the viscous fluid passage is provided in the pipe portion. Further, in the invention of claim 7, the viscous fluid passages are provided between the opposed side walls facing each other with a space therebetween. Thus, these inventions provide the desired viscous fluid path for placement of the magnet.

According to the eighth aspect of the invention, since the magnet is an electromagnet, the damping force can be easily controlled.

According to the ninth aspect of the invention, since the magnets are provided at both ends of the core of the electromagnet, a pair of magnets having different magnetic poles can be easily obtained and the damping force can be easily controlled. .

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an arrangement structure of magnets around a viscous fluid passage in a first embodiment of the present invention.

FIG. 2 is a perspective view showing an arrangement structure of magnets around a viscous fluid passage.

FIG. 3 is a perspective view showing another example of an arrangement structure of magnets around a viscous fluid passage.

FIG. 4 is a sectional view schematically showing the overall configuration of the damping device.

FIG. 5 is a view corresponding to FIG. 1 showing a structure in which one magnet is arranged laterally of a viscous fluid passage.

FIG. 6 is a view corresponding to FIG. 1 schematically showing an arrangement structure of magnets on the side of a viscous fluid passage in the second embodiment.

FIG. 7 is a perspective view showing an arrangement structure of magnets on a side of a viscous fluid passage.

FIG. 8 is a perspective view showing another example of the arrangement structure of the magnets on the side of the viscous fluid passage.

FIG. 9 is a plan view of a magnetic viscosity characteristic test device.

FIG. 10 is a perspective view showing a layout of magnets arranged around a nozzle of the magnetic viscous characteristic testing device.

FIG. 11 is a characteristic diagram showing the results of a magnetic viscosity characteristic test.

[Explanation of symbols]

A damping device 1 cylinder 4 Viscous fluid chamber 5 Magnetorheological fluid 7 pipe section 8 Viscous fluid passage 10 Moving part 12 magnets 13 Electromagnet 13 cores 17 Opposing side wall

Claims (9)

[Claims] 1. A viscous fluid passage through which a magnetorheological fluid flows according to the movement of a movable portion is provided, and a viscous resistance is imparted to the magnetorheological fluid in the viscous fluid passage by a magnet to attenuate the movement of the movable portion. The damping device as described above, wherein magnets paired around the viscous fluid passage are arranged to face each other while sandwiching the viscous fluid passage. 2. A viscous fluid passage through which a magnetorheological fluid flows according to movement of the movable portion is provided, and a viscous resistance is imparted to the magnetorheological fluid in the viscous fluid passage by a magnet to attenuate movement of the movable portion. A damping device as described above, wherein a plurality of magnets are arranged side by side along the viscous fluid passage along the viscous fluid passage. 3. The damping device according to claim 2, wherein at least one magnet of the plurality of magnets arranged along the viscous fluid passage is opposite to the viscous fluid passage, and the magnet sandwiches the viscous fluid passage. A damping device, which is arranged to face each other. 4. The damping device according to claim 1, wherein the magnetic poles on the viscous fluid passage side of both magnets facing each other across the viscous fluid passage are different from each other. 5. The damping device according to claim 2, wherein the magnetic poles on the viscous fluid passage side of the plurality of magnets arranged along the viscous fluid passage are alternately different from each other. 6. The damping device according to claim 1, wherein the viscous fluid passage is provided in the pipe portion. 7. The damping device according to claim 1, wherein the viscous fluid passages are provided between opposed side walls facing each other with a space therebetween. 8. The damping device according to claim 1, wherein the magnet is an electromagnet. 9. The damping device according to claim 1, wherein the magnets are both ends of the core of the electromagnet.