JP2019173933A - Mass damper - Google Patents

Abstract

To provide a mass damper which stably exerts a rotation inertia effect of a rotation mass without being influenced by a repeated input of a temperature and vibration energy, and can properly limit an axial force of the mass damper.SOLUTION: This mass damper 1 comprises: a nut 11c screwed to a screw shaft 11a connected to a first region in a system including a construction 3 at its one end part via balls 11b; an inner cylinder 12 connected to a second region at its one end part, and rotatably supporting the nut 11c; and a rotation mass 13 arranged so as to cover an external periphery of the nut 11c. A first magnet row 15 constituted of a plurality of first permanent magnets 15a which are arranged in a state of being aligned in a peripheral direction is arranged at an external peripheral face of the nut 11c, and a second magnet row 16 constituted of a plurality of second permanent magnets 16a arranged in a state of being aligned in the peripheral direction, opposing the plurality of first permanent magnets 15a of the first magnet row 15, and having counter magnetic poles is arranged at an internal peripheral face of the rotation mass 13.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a mass damper used for suppressing vibration of a structure or the like.

  As a conventional mass damper, for example, one disclosed in Patent Document 1 is known. The mass damper includes a screw shaft having one end connected to the first portion, a rotatable nut screwed to the screw shaft via a ball, and one end connected to the second portion to rotatably support the nut. And an inner cylinder that is rotatably supported by the inner cylinder. An axial force limiting mechanism is provided between the nut and the rotating mass. This axial force limiting mechanism is a mechanical type, and is disposed between the friction material that contacts the outer peripheral surface of the nut, the fastening bolt screwed into the rotating mass, and the friction material and the fastening bolt. It has a disc spring that urges it to the side.

  In this mass damper, when a relative displacement occurs between the first and second parts during an earthquake or the like, the linear motion of the screw shaft is converted into the rotational motion of the nut and transmitted to the rotational mass. Thereby, a rotation mass rotates and the vibration of a structure is suppressed by exhibiting the rotation inertia effect by a rotation mass. In addition, when the axial force of the mass damper (the axial load acting on the mass damper) reaches a predetermined value determined according to the spring constant of the disc spring of the axial force limiting mechanism or the tightening degree of the tightening bolt, the friction material and the nut When slippage occurs between them, the rotation of the rotating mass is suppressed and the axial force of the mass damper is limited.

Japanese Patent No. 5189213

  In the conventional mass damper described above, rotation of the rotary mass is suppressed and the axial force of the mass damper is limited by an axial force limiting mechanism using a friction material provided between the nut and the rotary mass. On the other hand, when large vibration energy is repeatedly input to the mass damper due to the occurrence of long-period ground motion, which is of particular concern in recent years, the frictional resistance is reduced by the heat generated by the friction material. There is a possibility that the axial force limitation of the mass damper cannot be performed properly as well as being unable to perform stably.

  The present invention has been made to solve the above-described problems, and stably exhibits the rotational inertia effect of the rotary mass without being affected by repeated input of temperature and vibration energy. An object is to provide a mass damper capable of appropriately limiting the axial force.

  In order to achieve this object, the invention according to claim 1 is a mass damper that is provided between a first part and a second part that are relatively displaced in a system including a structure, and that attenuates vibration energy. A screw shaft having a portion connected to the first portion, and a ball screw having a nut screwed to the screw shaft via a ball; and one end portion connected to the second portion and extending coaxially with the screw shaft; An inner cylinder that rotatably supports the outer periphery of the nut, a cylindrical rotary mass that is rotatable with respect to the nut, and a plurality that are arranged in the circumferential direction on the outer peripheral surface of the nut And a plurality of magnets arranged in the circumferential direction on the inner circumferential surface of the rotating mass, facing the plurality of magnets of the first magnet row and having a counter magnetic pole. A second magnet array configured, and That.

  According to this structure, the 1st and 2nd magnet row | line | column each comprised by the some magnet is arrange | positioned at the mutually opposing surface of the nut of a mass damper, and a rotation mass. The plurality of magnets of the first magnet array and the plurality of magnets of the second magnet array are arranged in a state of being arranged in the circumferential direction, face each other, and have the polarity of the counter electrode. With this configuration, an attractive force acts between a plurality of magnets in the first magnet row (hereinafter referred to as “first magnet”) and a plurality of magnets in the second magnet row (hereinafter referred to as “second magnet”).

  According to the mass damper of the present invention, when vibration energy is input to the structure during an earthquake or the like and a relative displacement occurs between the first and second parts, the relative straight line of the screw shaft connected to the first part. The nut is rotated by converting the motion into a rotational motion of the nut screwed onto the screw shaft. Along with the rotation of the nut, the rotation mass is rotated integrally with the rotation of the nut by the attractive force acting between the first and second magnets (hereinafter, this state is referred to as “integrated”). "Rotating state"). Thereby, the equivalent mass of the rotating mass is amplified with respect to the substantial amount, and the rotating inertia effect acting as a large reaction force (rotating inertia force) is exhibited, thereby suppressing the vibration of the structure.

  After that, when the rotation speed of the nut increases and the torque of the nut overcomes the attractive force of the magnet, the nut leaves a rotating mass and rotates while idling (hereinafter, this state is referred to as “detached rotation state”). , The rotating mass is greatly decelerated. Thereby, the axial force of a mass damper is restrict | limited by suppressing the rotational inertia force by a rotation mass. After that, when the rotation speed of the nut decreases and the torque of the nut falls below the attractive force of the magnet, the nut and the rotation mass automatically return from the detached rotation state to the integral rotation state, thereby The rotational inertia effect can be effectively exhibited again.

  The attractive force of the magnet does not show temperature dependency or repetitive dependency in the usage environment of the mass damper in the structure. Therefore, even when large vibration energy is repeatedly input to the structure, such as when long-period ground motion occurs, the rotational inertia effect of the rotating mass can be stabilized without being affected by repeated input of temperature and vibration energy. It can be demonstrated.

  Also, the greater the magnet attractive force, the greater the nut torque required to overcome this, and the rotational mass of the rotating mass accordingly increases. Furthermore, the attractive force of the magnet is generally determined according to the magnetic flux density, the cross-sectional area of the magnet, etc., and can be obtained with high accuracy. Therefore, by taking into account both the rotational inertia force required for the mass damper and the strength of the mass damper and appropriately setting the magnet's attractive force, the required rotational inertia force and vibration suppression performance can be secured, and the axial force of the mass damper can be secured. Restrictions can be made appropriately.

  According to a second aspect of the present invention, in the mass damper according to the first aspect, the cylindrical second rotating mass that is arranged to face the rotating mass and is rotatable with respect to the rotating mass, and the second rotating mass is opposed. A third magnet array composed of a plurality of magnets arranged in a circumferential direction on the facing surface of the rotating mass, and a state aligned in the circumferential direction on the facing surface of the second rotating mass facing the rotating mass. And a fourth magnet row that is arranged and is composed of a plurality of magnets that are opposed to the plurality of magnets of the third magnet row and have a counter magnetic pole.

  In this mass damper, a second rotating mass is provided in addition to the rotating mass, and third and fourth magnet arrays each composed of a plurality of magnets are arranged on the mutually opposing surfaces of the rotating mass and the second rotating mass. Yes. The plurality of magnets in the third magnet row and the plurality of magnets in the fourth magnet row are arranged in the circumferential direction, face each other, and have the polarity of the counter electrode. With this configuration, an attractive force acts between a plurality of magnets in the third magnet row (hereinafter referred to as “third magnet”) and a plurality of magnets in the fourth magnet row (hereinafter referred to as “fourth magnet”).

  Therefore, according to this mass damper, as the nut rotates, the rotating mass integrally rotates by the attractive force of the first and second magnets, and as the rotating mass rotates, by the attractive force of the third and fourth magnets. The second rotating mass rotates integrally with the rotating mass. Thereby, the rotation inertia effect by a 2nd rotation mass is exhibited, and the vibration of a structure can further be suppressed by adding to the rotation inertia effect of a rotation mass.

  In addition, when the rotational speed of the rotating mass increases and the torque of the rotating mass overcomes the attractive force of the third and fourth magnets, the rotating mass and the second rotating mass enter the separated rotational state, so that the second rotating mass becomes Decrease significantly. Thereby, the axial force of a mass damper is restrict | limited by suppressing the rotational inertia force by a 2nd rotation mass. After that, when the rotational speed of the rotating mass decreases and the torque of the rotating mass becomes lower than the attractive force of the magnet, the rotating mass and the second rotating mass automatically return from the detached rotational state to the integrated rotational state. Thus, the rotational inertia effect of the second rotational mass can be effectively exhibited again.

  According to a third aspect of the present invention, in the mass damper according to the second aspect, the second rotating mass is arranged in the axial direction with respect to the rotating mass, and is arranged so that the end faces face each other. It arrange | positions at the end surface of a rotation mass, and the 4th magnet row | line | column is arrange | positioned at the end surface of the 2nd rotation mass, It is characterized by the above-mentioned.

  According to this configuration, the second rotating mass is arranged in the axial direction with respect to the rotating mass, and the third and the second arranged on the mutually opposing end surfaces of the rotating mass and the second rotating mass, respectively. The integral rotation state and the separation rotation state of the rotary mass and the second rotary mass are switched by the attractive force of the four magnets. Thereby, the effect | action by Claim 2 can be acquired. Moreover, since the second rotating mass is arranged in a state aligned with the rotating mass in the axial direction, the mass damper in the radial direction can be made compact.

  According to a fourth aspect of the present invention, in the mass damper according to the second aspect, the second rotating mass is disposed on the outer peripheral side of the rotating mass, the third magnet row is disposed on the outer peripheral surface of the rotating mass, The magnet row is arranged on the inner peripheral surface of the second rotating mass.

  According to this configuration, the second rotating mass is arranged on the outer circumferential side of the rotating mass, and the attractive forces of the third and fourth magnets arranged on the outer circumferential surface of the rotating mass and the inner circumferential surface of the second rotating mass, respectively. Thus, the integral rotation state and the separation rotation state of the rotation mass and the second rotation mass are switched. Thereby, the effect | action by Claim 2 can be acquired. Further, since the second rotating mass is arranged on the outer peripheral side of the rotating mass, the mass damper in the axial direction can be made compact.

It is a figure which shows roughly the example which installed the seismic isolation apparatus containing the mass damper by embodiment of this invention in a structure. It is a longitudinal cross-sectional view which shows the mass damper by 1st Embodiment. It is sectional drawing which expands and shows the part shown by the arrow A of FIG. It is a longitudinal cross-sectional view which shows the mass damper by 2nd Embodiment. It is sectional drawing which expands and shows the part shown by the arrow B of FIG. It is a figure which shows a 4th magnet row | line and the 4th permanent magnet which comprises this.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example in which a mass damper 1 according to an embodiment is installed as a seismic isolation device in a structure 3 such as a building together with a laminated rubber bearing 2. A plurality of laminated rubber supports 2 (only two are shown) are provided, are fixed between the structure 3 and the foundation 4 and support the structure 3. A plurality of mass dampers 1 (only one is shown) are provided, and support members 5a projecting downward from the structure 3 and support members 5b projecting upward from the base 4 at both ends thereof. In between.

  As shown in FIG. 2, the mass damper 1 includes a ball screw 11, an inner cylinder 12, a rotating mass 13, a viscous body 14, first and second magnet arrays 15, 16, and the like.

  The ball screw 11 has a screw shaft 11a and a nut 11c that is screwed to the screw shaft 11a via a large number of balls 11b. The screw shaft 11a is movably connected to the first flange 17 via a universal joint 17a at the outer end, and the inner end protrudes from the nut 11c and extends into the inner cylinder 12. The nut 11c is made of, for example, a steel material, and is fitted to the inner cylinder 12 via the cross roller bearing 21 at the inner end portion and is rotatably supported.

  The inner cylinder 12 is made of a steel material and is arranged coaxially with the nut 11c, and is connected to the second flange 18 through the universal joint 18a so as to be immovable at the outer end portion.

  The rotary mass 13 is made of a material having a relatively large specific gravity, for example, a steel material, and is formed in a thick cylindrical shape. The rotating mass 13 is coaxially disposed outside the ball screw 11 and the inner cylinder 12 and is rotatably supported by the nut 11c and the inner cylinder 12 via bearings 22 and 22 at both ends.

  The viscous body 14 is filled in a gap G between the inner cylinder 12 and the rotary mass 13 in a liquid-tight state via seals 23 and 23. The viscous body 14 is made of a viscous material having a predetermined viscosity, such as silicon oil.

  As shown in FIG. 3, the first magnet row 15 is composed of a plurality (for example, eight) of permanent magnets (hereinafter referred to as “first permanent magnets”) 15a disposed on the outer peripheral surface of the nut 11c (only one). These first permanent magnets 15a are arranged at equal intervals in the circumferential direction. Each first permanent magnet 15a is composed of, for example, a disk-shaped ferrite magnet, and is housed in a non-magnetic case 15c together with a yoke (junction) 15b concentrically covered on the bottom and outer periphery thereof. ing.

  The second magnet row 16 is composed of a plurality of (for example, eight) permanent magnets (hereinafter referred to as “second permanent magnets”) 16 a arranged at equal intervals in the circumferential direction on the inner peripheral surface of the rotary mass 13. (Only one is shown), the number of which is the same as that of the first permanent magnet 15a. Each second permanent magnet 16a is composed of, for example, a disk-shaped ferrite magnet, like the first permanent magnet 15a, and a non-magnetic case together with a yoke 16b concentrically covered on the bottom and outer periphery thereof. 16c. As shown in FIG. 3, the first and second permanent magnets 15a and 16a have magnetic poles opposite to each other. With the above configuration, an attractive force acts between the first permanent magnet 15a and the second permanent magnet 16a.

  The mass damper 1 having the above configuration is connected and installed via, for example, first and second flanges 17 and 18 to support members 5a and 5b provided on the structure 3 and the base 4 in FIG. In this state, when a relative displacement occurs between the structure 3 and the foundation 4 due to the occurrence of an earthquake or the like, the linear motion of the screw shaft 11a with respect to the inner cylinder 12 connected thereto is converted into the rotational motion of the nut 11c, The nut 11c rotates.

  Along with the rotation of the nut 11c, the rotary mass 13 synchronizes with the nut 11c and rotates integrally at the same rotational speed (integrated rotation) by the attractive force acting between the first and second permanent magnets 15a and 16a. Status). By the rotation of the rotary mass 13, the equivalent mass of the rotary mass 13 is amplified with respect to a substantial amount, and a rotary inertia effect acting as a large rotary inertia force is exhibited, whereby the vibration of the structure 3 is suppressed.

  Thereafter, when the rotation speed of the nut 11c increases and the torque of the nut 11c overcomes the attractive force of the first and second permanent magnets 15a and 16a, the nut 11c leaves the rotating mass 13 and rotates while idling (detachment) The rotating mass 13 is greatly decelerated. Thereby, the axial force of the mass damper 1 is limited by suppressing the rotary inertia force by the rotary mass 13. After that, when the rotational speed of the nut 11c decreases and the torque of the nut 11c falls below the attractive force of the first and second permanent magnets 15a and 16a, the nut 11c and the rotary mass 13 are integrated from the detached rotational state. By automatically returning to the rotation state, the rotation inertia effect of the rotation mass 13 can be effectively exhibited again.

  The attractive force of the permanent magnet does not show temperature dependency or repetitive dependency in the usage environment of the mass damper in the structure. Therefore, even when large vibration energy is repeatedly input to the structure as in the case of occurrence of long-period ground motion, the rotational inertia effect of the rotating mass 13 is stabilized without being affected by repeated input of temperature and vibration energy. Can be demonstrated.

Further, the greater the attractive force of the first and second permanent magnets 15a, 16a, the greater the torque of the nut 11c necessary to overcome this, and the rotational inertia force of the rotary mass 13 accordingly increases. On the other hand, the attractive force F of the first and second permanent magnets 15a and 16a can be obtained with high accuracy by the following equation (1).
F = B ₀ ² · A / 2μ ₀ (1)
Here, B ₀ is the magnetic flux density in the facing space, A is the cross-sectional area of the first and second permanent magnets 15a and 16a, and μ ₀ is the vacuum permeability.

  Therefore, by taking into account both the rotational inertia force required for the mass damper 1 and the strength of the mass damper 1, the attraction force of the first and second permanent magnets 15a, 16a is appropriately set, so that the required rotational inertia force and vibration are obtained. While suppressing performance can be ensured, the axial force limitation of the mass damper 1 can be performed appropriately.

  FIG. 4 shows a mass damper 51 according to a second embodiment of the present invention. As is clear from comparison with FIG. 2, the mass damper 51 includes the third and fourth masses for rotating the second rotating mass 53 and the second rotating mass 53 with respect to the mass damper 1 according to the first embodiment described above. Magnet arrays 55 and 56 are added. Accordingly, the same reference numerals are given to the same or equivalent components as the mass damper 1, and the mass damper 51 will be described below with a focus on portions different from the mass damper 1.

  Similar to the mass damper 1, the mass damper 51 includes a rotating mass 13, a viscous body 14, and first and second magnet arrays 15 and 16, and these configurations are the same as those of the mass damper 1. The lengths of the rotating mass 13 and the viscous body 14 in the axial direction are set to be shorter than that of the mass damper 1.

  The second rotating mass 53 is made of a material having a relatively large specific gravity, for example, a steel material, is formed in a thick cylindrical shape, and has the same outer diameter and inner diameter as the rotating mass 13. The second rotating mass 53 is arranged in a state of being aligned with the rotating mass 13 in the axial direction, and end faces thereof are opposed to each other. The second rotating mass 53 is rotatably supported by the rotating mass 13 and the inner cylinder 12 via bearings 57 and 57 at both ends.

  As shown in FIG. 5, the third magnet array 55 includes a plurality (eight in this example) of permanent magnets (hereinafter referred to as “third permanent magnets”) 55 a arranged on the end face of the rotary mass 13 (1 These three permanent magnets 55a are arranged at equal intervals in the circumferential direction. Each third permanent magnet 55a is composed of, for example, a disk-shaped ferrite magnet, and is housed in a non-magnetic case 55c together with a yoke (junction) 55b concentrically placed on the bottom and outer periphery thereof. ing.

  As shown in FIGS. 5 and 6, the fourth magnet array 56 includes a plurality of (eight in this example) permanent magnets (hereinafter referred to as “first magnets”) arranged at equal intervals in the circumferential direction on the end surface of the second rotating mass 53. 56a ”), the number of which is the same as that of the third permanent magnet 55a. Each fourth permanent magnet 56a is composed of, for example, a disk-shaped ferrite magnet, like the third permanent magnet 55a, and a non-magnetic case together with a yoke 56b concentrically covered on the bottom and outer periphery thereof. 56c. Further, as shown in FIG. 5, the third and fourth permanent magnets 55a and 56a have a magnetic pole as a counter electrode. With the above configuration, an attractive force acts between the third permanent magnet 55a and the fourth permanent magnet 56a.

  According to the mass damper 51 having the above configuration, when relative displacement occurs between the structure 3 and the foundation 4 due to the occurrence of an earthquake or the like, the linear motion of the screw shaft 11a with respect to the inner cylinder 12 is caused by the nut as in the case of the mass damper 1. As the nut 11c rotates as the nut 11c rotates, the rotating mass 13 rotates integrally with the nut 11c by the attractive force of the first and second permanent magnets 15a and 16a. Inertial effect is exhibited.

  Further, along with the rotation of the rotating mass 13, the second rotating mass 53 rotates integrally with the rotating mass 13 by the attractive force of the third and fourth permanent magnets 55 a and 56 a. Thereby, the rotation inertia effect by the 2nd rotation mass 53 is exhibited, and by adding to the rotation inertia effect of the rotation mass 13, the vibration of the structure 3 can further be suppressed.

  In addition, when the rotational speed of the rotary mass 13 increases and the torque of the rotary mass 13 overcomes the attractive force of the third and fourth permanent magnets 55a and 56a, the rotary mass 13 and the second rotary mass 53 are separated from each other. Thus, the second rotating mass 53 is greatly decelerated. Thereby, the rotational inertia force by the 2nd rotation mass 53 is suppressed, and the axial force of the mass damper 51 is restrict | limited.

  Therefore, by taking into consideration both the rotational inertia force required for the mass damper 51 and the strength of the mass damper 51, the attraction force of the third and fourth permanent magnets 55a, 56a is appropriately set, so that the required rotational inertia force and vibration are obtained. While suppressing performance can be secured, the axial force limitation of the mass damper 51 can be performed appropriately.

  Thereafter, when the rotational speed of the rotary mass 13 decreases and the torque of the rotary mass 13 falls below the attractive force of the third and fourth permanent magnets 55a, 56a, the rotary mass 13 and the second rotary mass 53 are By automatically returning from the detached rotational state to the integral rotational state, the rotational inertia effect of the second rotational mass 53 can be effectively exhibited again.

  Furthermore, in the mass damper 51, the second rotary mass 53 is arranged in a state aligned with the rotary mass 13 in the axial direction, so that the mass damper 51 in the radial direction can be made compact.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the second embodiment, the second rotating mass 53 is arranged in a state of being aligned with the rotating mass 13 in the axial direction, and the third and fourth magnet arrays 55 and 56 are arranged on the opposing end surfaces thereof. Instead, the second rotating mass is coaxially arranged on the outer peripheral side of the rotating mass, the third magnet row is on the outer peripheral surface of the rotating mass, and the fourth magnet row is on the inner peripheral surface of the second rotating mass. You may arrange. Also with this configuration, the effect of the second embodiment described above can be obtained similarly. In this case, since the second rotating mass is disposed on the outer peripheral side of the rotating mass, the mass damper in the axial direction can be made compact.

  Moreover, in 2nd Embodiment, the axial force of the mass damper 51 is restrict | limited by the rotational inertia force of the 2nd rotation mass 53 being suppressed by the separation rotation of the rotation mass 13 and the 2nd rotation mass 53. The present invention is not limited to this. By changing the attractive force of the first and second permanent magnets 15a and 16a, the attractive force of the third and fourth permanent magnets 55a and 56a, etc., the nut 11c and the rotary mass 13 can be changed. The separation rotation may occur before the separation rotation of the rotation mass 13 and the second rotation mass 53. In that case, the axial force of the mass damper can be limited by simultaneously suppressing the rotational inertia forces of both the rotary mass 13 and the second rotary mass 53 by the separation rotation of the nut 11c and the rotary mass 13.

  In the embodiment, a ferrite magnet is used as the permanent magnet. However, it is merely an example, and a permanent magnet of another material, such as a neodymium magnet or an alnico magnet, may be used. Furthermore, instead of permanent magnets, electromagnets can be employed as the magnets constituting each magnet row. Also in this case, the effect by embodiment mentioned above can be acquired similarly.

  Moreover, the number of the 1st-4th permanent magnet shown to embodiment is an illustration to the last, can be increased / decreased suitably, and those shapes are not restricted to the circle | round | yen shown in embodiment, Other suitable shapes are also used. Can be adopted. Further, it is not essential to arrange the yoke concentrically with the permanent magnet, and the yoke and the case may be omitted.

  Moreover, although embodiment is an example which used the mass dampers 1 and 51 as a seismic isolation apparatus of a structure, you may use as a seismic control apparatus. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 Mass damper 3 Structure 5a Support member (first part)
5b Support member (second part)
11 Ball screw 11a Screw shaft 11b Ball 11c Nut 12 Inner cylinder 13 Rotating mass 15 First magnet row 15a First permanent magnet (magnet of the first magnet row)
16 Second magnet row 16a Second permanent magnet (magnet of second magnet row)
51 Mass damper 53 Second rotating mass 55 Third magnet row 55a Third permanent magnet (magnet of the third magnet row)
56 4th magnet row 56a 4th permanent magnet (magnet of the 4th magnet row)

Claims (4)

A mass damper that is provided between a first part and a second part that are relatively displaced in a system including a structure and attenuates vibration energy,
A screw shaft having one end connected to the first portion, and a ball screw having a nut screwed to the screw shaft via a ball;
An inner cylinder having one end connected to the second part, extending coaxially with the screw shaft, and rotatably supporting the nut;
A cylindrical rotating mass arranged to cover the outer periphery of the nut, and rotatable with respect to the nut;
A first magnet row composed of a plurality of magnets arranged in a circumferential direction on the outer peripheral surface of the nut;
A second magnet row that is arranged in a circumferential direction on the inner peripheral surface of the rotating mass, and that is configured by a plurality of magnets that are opposed to the plurality of magnets of the first magnet row and that have a counter magnetic pole;
A mass damper comprising: A cylindrical second rotating mass disposed so as to face the rotating mass and rotatable with respect to the rotating mass;
A third magnet array composed of a plurality of magnets arranged in a circumferential direction on the facing surface of the rotating mass facing the second rotating mass;
It is arranged in a state of being arranged in the circumferential direction on the facing surface of the second rotating mass facing the rotating mass, and is composed of a plurality of magnets facing the plurality of magnets of the third magnet row and having a counter magnetic pole. A fourth magnet row;
The mass damper according to claim 1, further comprising: The second rotating mass is arranged in an axial direction with respect to the rotating mass, and is arranged so that the end faces face each other,
The mass damper according to claim 2, wherein the third magnet row is disposed on the end face of the rotating mass, and the fourth magnet row is disposed on the end face of the second rotating mass. The second rotating mass is disposed on the outer peripheral side of the rotating mass,
The mass damper according to claim 2, wherein the third magnet row is disposed on an outer peripheral surface of the rotating mass, and the fourth magnet row is disposed on an inner peripheral surface of the second rotating mass.

Images