JP6712493B2 - Rotating damper - Google Patents

Description

The present invention relates to a rotary damper that makes damping force variable by utilizing a viscosity change of a magnetic fluid or a magnetorheological fluid.

As a conventional rotary damper, for example, there is a braking device described in Patent Document 1. In this braking device, a magnetic viscous fluid is enclosed in a case made of magnetic material, a rotary plate made of magnetic material is rotatably accommodated, and an electromagnetic coil is provided in the case. Then, by energizing the electromagnetic coil, a magnetic flux loop is formed to increase the viscosity of the magnetorheological fluid between the case and the rotating plate.

Therefore, the resistance to relative rotation between the case and the rotary plate is increased according to the viscosity of the magnetorheological fluid, and if one of the case and the rotary plate is fixed and used, a braking torque (damping force) can be generated. .. At this time, the braking torque can be made variable by controlling the energization of the electromagnetic coil.

However, in such a braking device, the damping force cannot be generated unless the electromagnetic coil is energized. Therefore, when the initial damping force is generated and the control for increasing or decreasing the damping force is performed, the power consumption is large. There is a problem.

JP, 2014-20539, A

The problem to be solved is that the power consumption is large when the initial damping force is changed to obtain the target damping force.

The present invention, in order to reduce the power consumption when changing the initial damping force to obtain a desired damping force, a case made of a magnetic material, and a magnetic material disposed in the case so as to be relatively rotatable. A rotating body, a working fluid that is housed in the case and is interposed between the case and the rotating body, and has a high viscosity due to the passage of magnetic flux, and a projecting member that projects into the case at the axial center of the case. And a permanent magnet forming a part of the support portion, the permanent magnet being configured to operate via the support portion. An initial magnetic flux of the magnetic flux passing through the fluid is formed, and the electromagnetic coil forms a control magnetic flux, which is canceled or added to the initial magnetic flux by energization, through the support portion, and acts on the working fluid. A rotary damper capable of adjusting magnetic flux , wherein the supporting portion is a hollow cylindrical shape, and is formed with a thick portion that is formed relatively thick in the radial direction and a portion that is relatively thin in the radial direction. The permanent magnet is characterized in that the permanent magnet is fitted with the outer periphery of the thin wall portion to form the support surface together with the thick wall portion, and has a revolving shape .

The rotary damper of the present invention can adjust the magnetic flux passing through the working fluid by adjusting the initial magnetic flux of the permanent magnet with the control magnetic flux generated by energization of the electromagnetic coil. By changing the initial damping force, it is possible to obtain the desired damping force. Therefore, it is possible to reduce power consumption when the target damping force is obtained by changing the initial damping force.

It is sectional drawing of a rotary damper. (Example 1) It is a graph which shows damping force characteristics. (Example 1) It is sectional drawing of a rotary damper. (Example 2)

The purpose of reducing the power consumption when changing the initial damping force to obtain the desired damping force was realized by adjusting the initial magnetic flux of the permanent magnet with the control magnetic flux of the electromagnetic coil.

That is, the rotary damper includes a case made of a magnetic material, a rotor made of a magnetic material that is rotatably disposed in the case, and a magnetic flux that is housed in the case and interposed between the case and the rotor. The working fluid that becomes more viscous by passing through it, the support part protruding into the case at the shaft center of the case, the electromagnetic coil attached to the support surface on the outer periphery of the support part, and part of the support part And a permanent magnet constituting the same.

The permanent magnet forms an initial magnetic flux of the magnetic flux passing through the working fluid through the support portion, and the electromagnetic coil forms a control magnetic flux that is canceled or added to the initial magnetic flux by energization through the support portion, The actual magnetic flux acting on the working fluid can be adjusted.

The support portion has a hollow cylindrical shape, and includes a thick portion formed relatively thick in the radial direction and a thin portion formed relatively thin in the radial direction. It is also possible to have a configuration in which the support surface is fitted with the outer periphery of the portion to form a support surface together with the thick portion.

In this case, in the support portion, the thick-walled portion is located on the proximal end side, the thin-walled portion is located at the tip end adjacent to the thick-walled portion, and the rotary damper has the permanent magnet fitted in the thin-walled portion. It may be configured to include a fastener for fastening to.

Alternatively, in the support portion, the thick-walled portion is removably positioned at the tip, the thin-walled portion is positioned adjacent to the thick-walled portion on the base end side, and the rotary damper is configured to have the permanent magnet fitted to the thin-walled portion. It may be configured to include a fastener that is fastened to the case side together with the thick portion.

The fastener may have a retaining collar that abuts the electromagnetic coil in the axial direction.

[Structure of rotary damper]
1 is a sectional view of a rotary damper according to a first embodiment of the present invention.

The rotary damper 1 of the present embodiment includes a case 3, a rotating body 5, an electromagnetic coil 7, and a permanent magnet 9. This rotary damper 1 uses one of the case 3 and the rotating body 5 which are relatively rotatable and is fixed, so that the braking according to the viscosity of the working fluid F described later against the relative rotation between the case 3 and the rotating body 5. Generates torque (damping force).

Such braking torque is obtained by the initial magnetic flux M1 itself by the permanent magnet 9 or by adjusting the initial magnetic flux M1 by the control magnetic flux M2 of the electromagnetic coil 7.

The case 3 is composed of a case body 11 and a lid 13.

The case body 11 is formed of a magnetic material as a whole, and the peripheral wall portion 15, the end wall portion 17, and the support portion 19 are integrally provided. As the magnetic material, for example, soft magnetic materials such as iron and silicon steel can be used.

The peripheral wall portion 15 is formed in a hollow cylindrical shape, and the end wall portion 17 is provided on the inner periphery on one side in the axial direction. The peripheral wall portion 15 is provided with a high magnetic resistance portion 15a made of a recess or a nonmagnetic material. The high magnetic resistance portion 15 a has a relatively high magnetic resistance with respect to other portions of the peripheral wall portion 15.

The end wall portion 17 has a circular shape as a whole, and is integrally formed on one side inner circumference of the peripheral wall portion 15 via a relatively thin connecting portion 17a. One side in the axial direction of the end wall portion 17 projects outside the case 3 with respect to the peripheral wall portion 15 and the connecting portion 17a. The other side of the end wall portion 17 in the axial direction projects into the case 3 with respect to the connecting portion 17a, and the outer peripheral portion forms a part of the working chamber 25a between the peripheral wall portion 15 and the outer peripheral portion.

On the inner peripheral portion of the end wall portion 17, a hole portion 17b through which the rotating shaft portion 5a of the rotating body 5 is inserted is provided. Around the hole 17b, a support portion 19 that extends into the case 3 with respect to the end wall portion 17 is provided. The support portion 19 is configured so as to project into the case 3 at the axial center portion of the case 3. Specifically, the support portion 19 has a hollow cylindrical shape, is integrally provided on the end wall portion 17, and projects into the case 3 in the axial direction. A clearance for passing the rotating body 5 is secured between the tip of the support portion 19 and the lid portion 13.

The support portion 19 includes a thick portion 19a and a thin portion 19b. In the present embodiment, the thick portion 19a is located on the base end side of the support portion 19 and is integrally provided on the end wall portion 17 of the case 3. The thick portion 19a is formed relatively thick in the radial direction. The thin portion 19b is formed to be relatively thin in the radial direction, and is located adjacent to the thick portion 19a on the tip side of the support portion 19.

A permanent magnet 9 is arranged on the outer periphery of the thin portion 19b as described later. A supporting surface 19c of the electromagnetic coil 7 is formed on the outer periphery of the supporting portion 19 by the thick portion 19a and the outer peripheral surface of the permanent magnet 9. The inner circumference of the support portion 19 constitutes a part of the hole portion 17b continuing from the end wall portion 17. The support portion 19 of the present embodiment has a tip portion 19d for attaching a collar 37, which will be described later, on the tip side of the thin portion 19b. The tip portion 19d is formed to be thinner than the thin portion 19a.

The lid 13 is fixed to the case body 11 on the inner circumference of the other side of the peripheral wall 15 by a stopper 21 such as a snap ring. A seal member 23 such as an O-ring is provided between the lid portion 13 and the case body 11.

The lid 13 has a disc shape as a whole formed of a non-magnetic material such as resin or non-magnetic metal. The non-magnetic metal is, for example, copper, aluminum or the like. The lid portion 13 defines the rotating body 5 and the storage chamber 25 for the working fluid F together with the peripheral wall portion 15, the end wall portion 17, and the support portion 19 of the case body 11. Further, the lid portion 13 is formed with a curved portion 13a on the outer peripheral side, and absorbs a volume change of the working fluid F in the case 3 by elastic deformation.

The rotating body 5 has a rotating shaft portion 5a and a rotating body body 5b integrally formed of a magnetic material.

The rotating shaft portion 5a is formed in a columnar shape, and the tip end portion is pulled out of the case 3 through the hole portion 17b of the case 3 as described above. The rotating shaft portion 5a is supported in the hole portion 17b of the case 3 via the bearings 27a and 27bb. As a result, the rotating body 5 is supported by the case 3 so as to be relatively rotatable via the rotating shaft portion 5a and the supporting portion 19. A spacer 29 holds a space between the bearings 27a and 27b.

Inside the case 7 with respect to the bearings 27a and 27b, a seal member 31 such as an X ring is arranged between the rotary shaft portion 5a and the hole portion 17b, and further inside the case 3 with respect to the seal member 31, a rotation member is provided. The filter 33 is arranged between the shaft portion 5a and the hole portion 17b. The filter 33 catches fine particles in the working fluid F so as not to reach the seal member 31 side, and protects the seal member 31. Inside the filter 33, the rotary body 5b is integrally connected to the base end of the rotary shaft 5a.

The rotary body 5b is a portion housed in the housing chamber 25 in the case 3. The rotary body 5b includes a rotary cylinder portion 5d on the outer peripheral portion of the rotary plate portion 5c.

The rotary plate portion 5c has a disc shape extending radially from the base end portion of the rotary shaft portion 5a in the accommodation chamber 25. The intermediate portion of the inner and outer peripheries of the rotating plate portion 5c has a bulging portion 5e bulging toward the electromagnetic coil 7 side in the axial direction, and the bulging portion 5e faces the support portion 19 of the case 3 in the radial direction. ing. Further, the bulging portion 5e is provided with an oil passage 5f penetrating in the axial direction. The outer peripheral portion of the rotary plate portion 5c faces the working chamber 25a of the housing chamber 25 and reaches the rotating tubular portion 5d located in the working chamber 25a.

The rotating tube portion 5d is provided along the peripheral wall portion 15 of the case 3 on the outer peripheral side of the electromagnetic coil 7. The rotating cylinder portion 5d is provided with a high magnetic resistance portion 5g made of a concave portion or a nonmagnetic material. The outer circumference of the rotary cylinder portion 5d radially opposes the inner circumference of the peripheral wall portion 15 with a gap, and the inner circumference of the rotary cylinder portion 5d has a gap between the outer circumference of the electromagnetic coil 7 and the end wall portion 17 of the case 3. To face each other in the radial direction. The working fluid F is housed in the housing chamber 25 of the case 3 and extends between the rotating body 5 and the case 3. As the working fluid F, a magnetorheological fluid called a magnetic fluid or an MR fluid is used. Therefore, the working fluid F increases its viscosity by the passage of the magnetic flux.

The electromagnetic coil 7 is attached to the support surface 19c on the outer periphery of the support portion 19 of the case 3. In the present embodiment, the electromagnetic coil 7 is abutted against the end wall portion 17 on one side in the axial direction, and a collar 37 described later is abutted on the other side in the axial direction so as to prevent the support portion 19 from coming off. ing.

The electromagnetic coil 7 can form a loop-shaped control magnetic flux M2 via the support portion 19 and the end wall portion 17. The control magnetic flux M2 is conceptually shown only in the upper half of FIG. 1, but is also symmetrically generated in the lower half.

The permanent magnet 9 constitutes a part of the support portion 19. In the present embodiment, a portion of the tip of the support portion 19 that overlaps the electromagnetic coil 7 in the radial direction is formed, and the tip end side surfaces of the permanent magnet 9 and the electromagnetic coil 7 are aligned in the axial direction. Although the permanent magnet 9 overlaps the electromagnetic coil 7 in the radial direction as a whole in the present embodiment, it may be arranged so as to partially overlap.

The permanent magnet 9 of the present embodiment is formed in a revolving shape, particularly an annular shape. The permanent magnet 9 is fitted on the outer periphery of the thin portion 19b of the support portion 19 of the case 3, and constitutes the support surface 19c together with the thick portion 19a as a part of the support portion 19 as described above. The permanent magnet 9 has magnetic poles on both sides in the axial direction, and forms a loop-shaped initial magnetic flux M1 on the magnetic path of the control magnetic flux M2. The initial magnetic flux M1 is also conceptually shown only in the upper half of FIG. 1, but is also symmetrically generated in the lower half.

The initial magnetic flux M1 composes an actual magnetic flux acting on the working fluid F by itself or by being offset with or added to the control magnetic flux M2. That is, when the electromagnetic coil 7 is not energized, the initial magnetic flux M1 becomes the actual magnetic flux as it is. On the other hand, when the electromagnetic coil 7 is energized, when the initial magnetic flux M1 and the control magnetic flux M2 are in opposite directions, the initial magnetic flux M1 is canceled by the control magnetic flux M2 to become a real magnetic flux, and in the same direction, the initial magnetic flux M1 becomes the control magnetic flux M2. Is added to form the actual magnetic flux.

The permanent magnet 9 is provided with fastening holes 9a at predetermined intervals in the circumferential direction, and is fastened to the thick portion 19a by the fastener 35 through the holes 9a.

The fastener 35 of this embodiment includes a collar 37 and a bolt 39 made of a magnetic material. Similar to the permanent magnet 9, the collar 37 is formed in a circular ring shape and fits into the tip portion 19d of the support portion 19.

Specifically, the tip end portion 19d of the support portion 19 projects in the axial direction with respect to the permanent magnet 9 in a state where the permanent magnet 9 is fitted in the thin portion 19b. A collar 37 is fitted on the outer circumference of the tip portion 19d and is abutted on the permanent magnet 9 in the axial direction.

Further, the collar 37 has an inner diameter smaller than that of the permanent magnet 9 and is arranged such that the inner peripheral surface thereof projects radially inward with respect to the permanent magnet 9. Furthermore, the outer diameter of the collar 37 is larger than that of the permanent magnet 9, and the outer peripheral surface of the collar 37 is arranged so as to project radially outward with respect to the permanent magnet 9. Due to the protrusion on the outer peripheral surface side, the collar 37 is also abutted on the electromagnetic coil 7 in the axial direction.

The collar 37 is provided with fastening holes 37a corresponding to the holes 9a of the permanent magnet 9 at predetermined intervals in the circumferential direction. The hole portion 37a of the collar 37 accommodates the head portion 39a of the bolt 39 and pulls out the shaft portion 39b of the bolt 39 on the permanent magnet 9 side. The shaft 39b of the pulled-out bolt 39 is inserted into the hole 9a of the permanent magnet 9, and the tip of the bolt 39 is screwed into the female screw portion 19f of the thick portion 19a.

Thus, the permanent magnet 9 is fastened to the thick portion 19a. In this embodiment, the fastening of the permanent magnet 9 is used to prevent the permanent magnet 9 from coming off by the collar 37 of the fastener 35.

[Operation of rotary damper]
The rotary damper 1 is used, for example, by connecting (coupling) the case 3 to the fixed side and the rotary shaft portion 5a of the rotary body 5 to the movable side to be damped. The case 3 may be connected to the movable side and the rotary shaft portion 5a may be connected to the fixed side.

In this state, when the actual magnetic flux is formed, the rotary damper 1 increases the viscosity of the working fluid F between the rotating body 5 and the case 3, and applies the braking torque or the damping force to the input torque input from the movable side. generate.

Similar to the initial magnetic flux M1, the actual magnetic flux passes through the support portion 19 and the end wall portion 17 and reaches the peripheral wall portion 15 of the case 3 via the rotating tubular portion 5d of the rotating body 5. Between the peripheral wall portion 15 and the rotary tubular portion 5d, the high magnetic resistance portions 5g and 15a are avoided so as to reciprocate between the rotary tubular portion 5d and the peripheral wall portion 15. Then, the rotary cylinder portion 5d of the rotary body 5 reaches the support portion 19 via the rotary plate portion 5c and the collar 37.

As described above, when the electromagnetic coil 7 is not energized, the initial magnetic flux M1 becomes the actual magnetic flux as it is, and when the electromagnetic coil 7 is energized, the control magnetic flux M2 is offset or added to the initial magnetic flux M1 to become the actual magnetic flux. Therefore, in the present embodiment, it is possible to generate an initial damping force when the electromagnetic coil 7 is not energized and change the initial damping force according to the energization of the electromagnetic coil 7 to obtain a target damping force.

FIG. 2 is a graph showing damping force characteristics of the rotary damper 1. When the initial magnetic flux M1 and the control magnetic flux M2 are in opposite directions, the initial magnetic flux M1 and the control magnetic flux M2 cancel each other out. Therefore, when the current of the electromagnetic coil 7 is increased like the line segment SA, the initial damping is performed. The damping force decreases from the force. Therefore, when the initial magnetic flux M1 and the control magnetic flux M2 are in opposite directions, the characteristics are in opposite directions as compared with the prior art in which the permanent magnet 9 shown by the line segment SC is not provided.

When the initial magnetic flux M1 and the control magnetic flux M2 are in the same direction, the control magnetic flux M2 is added to the initial magnetic flux M1. Therefore, when the current of the electromagnetic coil 7 is increased like the line segment SB, the initial damping force is changed. It has the characteristic that the damping force increases. Therefore, when the initial magnetic flux M1 and the control magnetic flux M2 are in the same direction, it is possible to obtain a characteristic which is increased by the amount of the initial damping force, like the line segment SB, as compared with the conventional technique of the line segment SC.

[Effect of Example 1]
The rotary damper 1 according to the present embodiment includes a case 3 made of a magnetic material, a rotary body 5 made of a magnetic material rotatably arranged in the case 3, a case 3 and a rotary body 5 housed in the case 3. Between the working fluid F and the working fluid F, the viscosity of which increases due to the passage of magnetic flux, the support portion 19 projecting into the case 3 at the axial center of the case 3, and the support surface on the outer periphery of the support portion 19. An electromagnetic coil 7 attached to 19c and a permanent magnet 9 forming a part of the support portion 19 are provided, and the permanent magnet 9 forms an initial magnetic flux M1 of a magnetic flux passing through the working fluid F via the support portion 19. The electromagnetic coil 7 forms a control magnetic flux M2, which is canceled or added to the initial magnetic flux M1 by the energization, via the support portion 19, so that the actual magnetic flux acting on the working fluid F can be adjusted.

Therefore, the rotary damper 1 of the present embodiment can generate an initial damping force when the electromagnetic coil 7 is not energized and change the initial damping force according to the energization of the electromagnetic coil 7 to obtain a target damping force. Become. That is, it is possible to reduce the power consumption when the target damping force is obtained by changing the initial damping force.

The support portion 19 has a hollow tubular shape, and includes a thick portion 19 a formed to be relatively thick in the radial direction and a thin portion 19 b formed to be relatively thin in the radial direction. Is a circular shape that is fitted to the outer periphery of the thin portion 19b to form the support surface 19c together with the thick portion 19a.

Therefore, in the present embodiment, since a part of the supporting portion 19 supporting the electromagnetic coil 7 is entirely replaced with the permanent magnet 9, there is no increase in size. Moreover, since the permanent magnet 9 is positioned on the inner circumference of the electromagnetic coil 7, it is possible to reliably cancel or add the control magnetic flux M2 to the initial magnetic flux M1.

Further, in the rotary damper 1, the thick wall portion 19a of the support portion 19 is located on the base end side, the thin wall portion 19b of the support portion 19 is located at the tip end adjacent to the thick wall portion 19a, and is fitted to the thin wall portion 19b. Since the fastener 35 for fastening the permanent magnet 9 to the thick wall portion is provided, the permanent magnet 9 can be easily assembled.

Further, in the present embodiment, since the fastener 35 has the retaining collar that abuts the electromagnetic coil 7 in the axial direction, the retaining of the electromagnetic coil 7 can be realized by utilizing the fastening of the permanent magnet 9. Therefore, the structure can be simplified and the assembling can be facilitated.

FIG. 3 is a sectional view of a rotary damper according to a second embodiment of the present invention. Since the second embodiment has the same basic structure as that of the first embodiment, the same reference numerals or the same reference numerals with A added to the corresponding portions are used, and the duplicate description is omitted.

In the rotary damper 1A of the present embodiment, the thick portion 19Aa of the support portion 19A is removably positioned on the tip side, and the thin portion 19Ab of the support portion 19A is positioned on the base end side adjacent to the thick portion 19Aa. It is a thing.

The supporting portion 19A of the present embodiment is configured to be thin as a whole except for the removable thick portion 19Aa. Specifically, the support portion 19A is provided with a thin portion 19Ab, an intermediate portion 19Ae, and a tip portion 19Ad in this order from the base end side.

The thin portion 19Ab is integrally provided adjacent to the end wall portion 17A of the case 3A, and the permanent magnet 9 is fitted to the outer periphery thereof. The intermediate portion 19Ae projects in the axial direction with respect to the permanent magnet 9, and the thick portion 19Aa is fitted to the outer periphery. The intermediate portion 19Ae is thinner than the thin portion 19Ab, like the tip portion 19Ad. The tip portion 19Ad has the same structure as that of the first embodiment, has the same thickness as the middle portion 19Ae, and has the collar 37 fitted to the outer periphery thereof.

The thick portion 19Aa and the permanent magnet 9 are located in a range that overlaps with the electromagnetic coil 7 in the radial direction as a whole to form the support surface 19Ac.

The thick portion 19Aa has a circular shape, and particularly has a cylindrical shape. The thick portion 19Aa of this embodiment is made of a magnetic material and is provided integrally with the collar 37A of the fastener 35. The thick portion 19Aa may be formed separately from the collar 37A. The inner peripheral surface of the thick portion 19Aa is located radially inward of the permanent magnet 9, and the outer peripheral surface of the thick portion 19Aa is flat with the permanent magnet 9 in the axial direction.

The thick portion 19Aa is fastened to the end wall portion 17A on the case 3 side together with the permanent magnet 9 as a part of the collar 37A. Therefore, the thick portion 19Aa is provided with a hole portion 37Aa continuing from the collar 37A, and the shaft portion 39Ab of the bolt 39A is inserted therethrough. The shaft portion 39Ab of the bolt 39A is further inserted through the hole 9a of the permanent magnet 9, and the tip is screwed into the female screw portion 17Ac of the end wall portion 17A.

Thus, in the present embodiment, the thick portion 19Aa of the support portion 19A is removably located on the tip side, the thin portion 19Ab of the support portion 19A is located adjacent to the thick portion 19Aa on the base end side, The fastener 35A fastens the permanent magnet 9 fitted to the thin portion 19Ab of the support portion 19A to the end wall portion 17A on the case 3 side together with the thick portion 19Aa.

Therefore, in this embodiment, the sizes of the thick portion 19Aa and the permanent magnet 9 in the axial direction can be easily changed, and the rotary damper 1A having different characteristics can be easily obtained.

In addition, the same operational effects as those of the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1... Rotation damper 3... Case 5... Rotating body 7... Electromagnetic coil 9... Permanent magnet 19... Support part 19a... Thick part 19b... Thin part 19c. ..Supporting surface 19d...Base end 19e...Tip 35...Fastening 37...Color F...Working fluid M1...Initial magnetic flux M2...Control magnetic flux

Claims (4)

A case made of magnetic material,
A rotating body made of a magnetic material, which is disposed in the case so as to be relatively rotatable,
A working fluid that is housed in the case and has a high viscosity due to the magnetic flux passing through the case and the rotating body,
A support portion projecting into the case at the axial center of the case;
An electromagnetic coil attached to a supporting surface on the outer periphery of the supporting portion,
A permanent magnet forming a part of the support,
The permanent magnet forms an initial magnetic flux of a magnetic flux passing through the working fluid through the supporting portion, and the electromagnetic coil cancels or adds a control magnetic flux to the initial magnetic flux by energization of the supporting portion. A rotary damper capable of adjusting the actual magnetic flux acting on the working fluid ,
The support portion is a hollow cylinder, and includes a thick portion formed to be relatively thick in the radial direction, and a thin portion formed to be relatively thin in the radial direction,
The permanent magnet has a revolving shape that is fitted to the outer periphery of the thin portion to form the support surface together with the thick portion,
A rotary damper characterized by that. The rotary damper according to claim 1 , wherein
The support portion, the thick portion is located on the proximal end side, the thin portion is located on the distal end side adjacent to the thick portion,
A fastener for fastening the permanent magnet fitted to the thin portion to the thick portion,
A rotary damper characterized by that. The rotary damper according to claim 1 , wherein
In the support portion, the thick portion is removably located on the tip side, and the thin portion is located on the base end side adjacent to the thick portion,
A fastener for fastening the permanent magnet fitted to the thin portion to the case side together with the thick portion,
A rotary damper characterized by that. The rotary damper according to claim 2 or 3 , wherein
The fastener has a retaining collar that abuts the electromagnetic coil in an axial direction,
A rotary damper characterized by that.

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