JP2021042765A - Dynamic damper - Google Patents

Abstract

To provide a dynamic damper capable of suppressing vibrations with various frequencies without performing complicated control.SOLUTION: A dynamic damper 1 includes: a magnetic spring unit 6 having a stator 11, permanent magnets 12 and 13 attached to the stator 11, and a movable element 14 which is arranged so as to reciprocate in a direction of the moving direction of the movable element by at least a magnetic force caused by a magnetic flux generated by the permanent magnets 12 and 13; a mechanical spring unit 7 which is fixed to the stator 11 and has leaf springs 17 and 18 to which the movable element 14 is attached movably in a movable element moving direction; and a spring constant switching unit 8 which switches magnitude of a synthesized spring constant determined by a spring constant of the magnetic spring unit 6 and a spring constant of the mechanical spring unit 7.SELECTED DRAWING: Figure 3

Description

The present invention relates to a dynamic vibration absorber.

A passive mass damper applied to a vibration damping device that suppresses vibration of a vibration damping object (for example, an automobile or the like) has been widely known. A passive mass damper includes a spring element and a mass body attached to a vibration damping object via the spring element, and vibrates at a resonance frequency and a frequency in the vicinity thereof, which is determined by the spring constant of the spring element and the mass of the mass body. Suppress.

Further, for example, Patent Document 1 discloses an active vibration damping device having a linear motor. For example, an electromagnetic motor called a reciprocating motor is applied to the linear motor. The reciprocating motor includes a stator having a permanent magnet, a mover that is reciprocally supported by the stator via a leaf spring, and a coil, and can reciprocally drive the mover by passing an alternating current through the coil. It is configured in. The active vibration damping device detects, for example, the vibration of the vibration damping object being vibrated, controls the linear motor based on the detected vibration information, and reciprocates the mover. As a result, a reaction force that cancels the vibration of the vibration damping object is generated, and the vibration is suppressed.

Japanese Unexamined Patent Publication No. 2012-237449

In a passive mass damper, the spring constant and mass are predetermined. Therefore, in order to suppress vibration at a frequency significantly different from the resonance frequency of the dynamic vibration absorber, the spring constant and / or mass must be adjusted by exchanging the spring element and / or the mass body. Therefore, for example, when there are a plurality of vibration sources that can cause vibration of the vibration damping object (that is, there are a plurality of types of vibration frequencies generated by the vibration sources), the vibration may not be sufficiently suppressed. On the other hand, in the active vibration damping device described in Patent Document 1, by controlling the frequency of the alternating current based on the detected vibration information, the frequency of the vibration of the mover itself is changed to vibrate at various frequencies. It is conceivable to suppress. However, in order to suppress the vibration of the vibration damping object in this way, very complicated and delicate control is required, which leads to problems such as an increase in the cost of the control means.

An object of the present invention is to provide a dynamic vibration absorber capable of suppressing vibrations of various frequencies without performing complicated control.

The dynamic vibration absorber of the first invention is a dynamic vibration absorber that is attached to a vibration damping object and suppresses vibration of the vibration damping object, and includes a stator, a permanent magnet attached to the stator, and a permanent magnet. A magnetic spring portion having at least a mover provided so as to be reciprocally movable in a predetermined direction by a magnetic force generated by a magnetic flux generated by the permanent magnet, and a mover fixed to the stator and having the mover in the predetermined direction. The mechanical spring portion having the first leaf spring that can be deformed in a predetermined direction, which is movably attached to the magnetic spring portion, and the synthetic spring constant determined by the spring constant of the magnetic spring portion and the spring constant of the mechanical spring portion are switched. It is provided with a spring constant switching unit.

In the Tuned Mass Damper of the present invention, at least the mover functions as a mass body, and the mechanical spring portion and the magnetic spring portion function as spring elements. Further, in the Tuned Mass Damper, the combined spring constant is switched by the spring constant switching unit, whereby the resonance frequency of the Tuned Mass Damper is switched. That is, the dynamic vibration absorber does not generate a reaction force by controlling the movement of the mover at any time. Therefore, vibrations of various frequencies can be suppressed without complicated control.

In the dynamic vibration absorber of the second invention, in the first invention, the spring constant switching unit generates a magnetic flux for changing the position of the mover in the predetermined direction when a current is flowing. It has a coil and a control unit that supplies power to the coil. The control unit causes the coil to flow a current, and the spring of the first leaf spring responds to a change in the position of the mover in the predetermined direction. By locating the mover in the spring constant change region where the constant changes, the spring constant of the mechanical spring portion is switched according to the magnitude of the current flowing through the coil.

In the present invention, the strength of the magnetic flux can be changed by changing the magnitude of the current flowing through the coil, and the position of the mover located in the spring constant change region can be changed. As a result, the spring constant of the mechanical spring portion can be switched, and the synthetic spring constant can be switched.

In the first or second invention, the dynamic vibration absorber of the third invention has the mechanical spring portion fixed to the stator and arranged side by side with the first leaf spring in the predetermined direction. The spring constant switching unit includes a second leaf spring that can be deformed into a spring, and a coil that generates a magnetic flux for changing the position of the mover in the predetermined direction when a current is flowing. A first state including a control unit that supplies power to the coil, and the first leaf spring is not in contact with the second leaf spring according to the magnitude of the power supplied to the coil by the control unit. The feature is that the spring constant of the mechanical spring portion is switched by changing the state of the mechanical spring portion between the first leaf spring and the second state in which the first leaf spring is in contact with the second leaf spring. It is something to do.

In the present invention, the spring constant of the mechanical spring portion can be increased by bringing the first leaf spring into contact with the second leaf spring so that these leaf springs can be integrally deformed. As a result, the spring constant of the mechanical spring portion can be significantly different between when the first leaf spring is not in contact with the second leaf spring and when it is in contact with the second leaf spring. Therefore, the spring constant of the mechanical spring portion can be effectively switched.

In the dynamic vibration absorber of the fourth invention, in any one of the first to third inventions, the mover and the permanent magnet are arranged so as to face each other in an intersecting direction intersecting the predetermined direction, and the spring. The constant switching unit is characterized in that the spring constant of the magnetic spring portion is switched by changing the size of the gap in the crossing direction between the mover and the permanent magnet.

In the present invention, the strength of the magnetic flux flowing between the permanent magnet and the mover can be changed by changing the size of the gap between the mover and the permanent magnet. As a result, the spring constant of the magnetic spring portion can be switched by changing the restoring force (force for returning the mover to its original position) when the mover moves in a predetermined direction.

In the dynamic vibration absorber of the fifth invention, in the first invention, the stator is the permanent magnet, and the magnetic pole having the first polarity in the intersecting direction intersecting the predetermined direction is the mover. A first permanent magnet arranged so as to face one end in a predetermined direction and a magnetic pole having a second polarity opposite to the first polarity in the intersecting direction are in the predetermined direction of the mover. It has a second permanent magnet arranged so as to face the other end of the magnet, and the spring constant switching portion is between the first permanent magnet and the mover when a current is flowing. It is characterized by comprising a coil for switching the spring constant of the magnetic spring portion by generating a magnetic flux that strengthens or weakens both the magnetic flux flowing in the magnet and the magnetic flux flowing between the second permanent magnet and the mover. Is.

In the present invention, the magnetic flux generated when a current is flowing through the coil strengthens both the magnetic flux flowing between the first permanent magnet and the mover and the magnetic flux flowing between the second permanent magnet and the mover. be able to. As a result, the restoring force of the magnetic spring can be strengthened, and the spring constant of the magnetic spring portion can be increased. Conversely, by weakening both the magnetic flux flowing between the first permanent magnet and the mover and the magnetic flux flowing between the second permanent magnet and the mover, the restoring force of the magnetic spring is weakened, and the spring of the magnetic spring portion. The constant can be reduced. As described above, the spring constant of the magnetic spring portion can be switched.

It is a schematic diagram of the dynamic vibration absorber and its peripheral configuration which concerns on 1st Embodiment. It is a perspective view of the linear motor which constitutes a dynamic vibration absorber. It is explanatory drawing which shows the flow of magnetic flux. (A) and (b) are explanatory views which show the deformation of a leaf spring. (A) is a graph showing the relationship between the amount of deformation of the leaf spring and the restoring force, and (b) is a graph showing the relationship between the amount of deformation of the leaf spring and the spring constant. (A) is a graph showing the relationship between the direct current and the amount of change in the spring constant, and (b) is a graph showing the relationship between the direct current and the amount of change in the resonance frequency. It is a schematic diagram of the linear motor which concerns on 2nd Embodiment. (A) and (b) are explanatory views which show the operation of a linear motor. It is a schematic diagram of the linear motor which concerns on the modification of 2nd Embodiment. (A) and (b) are explanatory views which show the operation of a linear motor. It is a schematic diagram of the linear motor which concerns on 3rd Embodiment. (A) and (b) are explanatory views which show the operation of a linear motor. (A) and (b) are schematic views of the linear motor according to the fourth embodiment. It is a schematic diagram of the dynamic vibration absorber which concerns on 5th Embodiment. (A) and (b) are explanatory views showing the magnetic flux passing through the magnetic spring part. (A) and (b) are schematic views of a dynamic vibration absorber according to a modified example of the fifth embodiment.

<First Embodiment>
Next, the outline of the dynamic vibration absorber 1 according to the first embodiment of the present invention will be described with reference to the schematic diagram of FIG. The dynamic vibration absorber 1 is a device that is attached to the vibration damping object 2 and suppresses the vibration of the vibration damping object 2. The vibration damping object 2 is, for example, an automobile frame or the like. As shown in FIG. 1, the dynamic vibration absorber 1 includes a linear motor 3 fixed to a vibration damping object 2 and a control unit 4 for supplying electric power to the linear motor 3.

The linear motor 3 is, for example, an electromagnetic motor called a reciprocating motor. The linear motor 3 has a mover 14 (described later) that functions as a mass body, and a spring element and a damping element. The mover 14 attached to the vibration damping object via the spring element and the damping element vibrates as a shoulder substitute for the vibration damping object 2, thereby suppressing the vibration of the vibration damping object 2. The details of the spring element will be described later. Since the damping element is not closely related to the present invention, the description of the damping element will be omitted. The control unit 4 supplies electric power to the linear motor 3 (details will be described later).

(Linear motor)
The configuration of the linear motor 3 will be described with reference to FIGS. 2 and 3. FIG. 2 is a perspective view of the linear motor 3. FIG. 3 is an explanatory diagram showing the flow of magnetic flux when no current is flowing through the coils 15 and 16 (described later). As shown in FIG. 2, the linear motor 3 includes a stator 11, permanent magnets 12 and 13, a mover 14, coils 15 and 16, and leaf springs 17 and 18 (the first leaf spring of the present invention). Has. Hereinafter, the direction in which the mover 14 can reciprocate as shown in FIG. 2 is defined as the mover movement direction (predetermined direction of the present invention). The direction in which the mover 14 faces the permanent magnets 12 and 13, which is orthogonal to the mover movement direction, is defined as the orthogonal direction.

The stator 11 is, for example, a substantially tubular magnetic member formed of laminated steel plates stacked in the moving element moving direction. The stator 11 is arranged so as to surround the mover 14. The stator 11 has a convex portion 11a arranged on one side of the mover 14 and a convex portion 11b arranged on the other side of the mover 14 in an orthogonal direction orthogonal to the moving direction of the mover. A permanent magnet 12 is fixed to the other end of the convex portion 11a in the orthogonal direction. A permanent magnet 13 is fixed to one end of the convex portion 11b in the orthogonal direction.

As shown in FIG. 3, the permanent magnets 12 and 13 have a shape extending along the moving element moving direction. One side portion of the permanent magnet 12 in the moving element moving direction has a first polarity (for example, N pole). The other side portion of the permanent magnet 12 in the moving element moving direction (see the hatched portion in FIG. 3) has a second polarity opposite to the first polarity (for example, the S pole). The permanent magnet 12 is fixed to the other end of the convex portion 11a in the orthogonal direction. Further, one side portion of the permanent magnet 13 in the mover moving direction has a second polarity, and the other side portion of the permanent magnet 13 in the mover moving direction has a first polarity. The permanent magnet 13 is fixed to the other end of the convex portion 11b in the orthogonal direction. The permanent magnets 12 and 13 are arranged so as to face the mover 14 in the orthogonal direction. A gap is formed between the permanent magnets 12 and 13 and the mover 14.

The mover 14 is, for example, a substantially cylindrical magnetic member formed of laminated steel plates stacked in the mover moving direction. The mover 14 is arranged so as to face the permanent magnets 12 and 13 in the orthogonal direction. The end portion of the mover 14 on one side in the mover movement direction faces the permanent magnets 12 and 13 in the direction orthogonal to the one side portion in the mover movement direction. The other end of the mover 14 in the mover moving direction faces the other side of the permanent magnets 12 and 13 in the mover moving direction in the direction orthogonal to each other. The mover 14 is fixed to a shaft 19 extending in the mover moving direction. The shaft 19 is supported by the stator 11 via leaf springs 17 and 18. In this way, the mover 14 is attached to the stator 11 and is configured to be movable in the mover moving direction.

The coil 15 is wound so as to surround the convex portion 11a so that its axial direction is along the orthogonal direction. Similarly, the coil 16 is wound so as to surround the convex portion 11b. The winding direction of the coil 15 and the winding direction of the coil 16 are the same. The coils 15 and 16 are electrically connected to the control unit 4.

The leaf springs 17 and 18 are substantially 8-shaped (see FIG. 2) spring members arranged in a virtual plane substantially orthogonal to the moving direction of the mover. That is, the leaf springs 17 and 18 generally have a shape in which two rings are arranged side by side in the orthogonal direction. At the center of the leaf spring 17 in the orthogonal direction, one end of the shaft 19 in the moving element moving direction is fixed. The other end of the shaft 19 in the moving element moving direction is fixed to the central portion of the leaf spring 18 in the orthogonal direction. Both ends of the leaf spring 17 in the orthogonal direction are fixed to one end of the stator 11 in the mover moving direction. Both ends of the leaf spring 18 in the orthogonal direction are fixed to the other end of the stator 11 in the mover moving direction. The leaf springs 17 and 18 are configured to be deformable in the moving element moving direction. Both ends of the leaf springs 17 and 18 in the orthogonal direction are not displaced, and the central portion in the orthogonal direction is displaced.

The linear motor 3 having the above configuration functions as a dynamic vibration absorber including a mass body and a spring element regardless of whether or not electric power is supplied by the control unit 4. As described above, the mover 14 corresponds to a mass body. A mass body (not shown) different from the mover 14 may be fixed to the mover 14. Further, the linear motor 3 has the following magnetic spring element and mechanical spring element as spring elements. That is, the linear motor 3 has a magnetic spring portion 6 that functions as a magnetic spring element and a mechanical spring portion 7 that functions as a mechanical spring element.

The magnetic spring portion 6 has the above-mentioned stator 11, permanent magnets 12, 13 and mover 14. That is, a magnetic circuit through which magnetic flux flows is formed by the stator 11, the permanent magnets 12, 13, and the mover 14. Specifically, the magnetic flux generated by the permanent magnets 12 and 13 flows as shown by arrows 101, 102, 103 and 104 in FIG. 3, for example. That is, on one side in the mover moving direction, the magnetic flux flows toward the other side in the orthogonal direction. On the other side in the mover moving direction, magnetic flux flows toward one side in the orthogonal direction. As a result, a magnetic force is generated to maintain the position of the mover 14 in the mover moving direction at a predetermined reference position. For example, when no current is flowing through the coils 15 and 16, the reference position is the center position of the permanent magnets 12 and 13 in the moving element moving direction. When an external force is applied to the mover 14 and the mover 14 is displaced from the reference position, a magnetic force that tries to return the mover 14 to the reference position acts on the mover 14 as a restoring force. In this way, the magnetic spring portion 6 functions as a magnetic spring element. The spring constant of the magnetic spring portion 6 is a proportional coefficient between the displacement amount of the mover 14 and the magnetic force (restoring force).

The mechanical spring portion 7 has the leaf springs 17 and 18 described above. That is, when the mover 14 is displaced in the mover moving direction, the leaf springs 17 and 18 are deformed in the mover moving direction, and an elastic restoring force acts on the mover 14. In this way, the mechanical spring portion 7 functions as a mechanical spring element. The spring constant of the mechanical spring portion 7 (proportional coefficient between the displacement amount of the mover and the restoring force) is determined by the spring constants of the leaf springs 17 and 18. The magnetic spring portion 6 and the mechanical spring portion 7 are arranged in parallel. The resonance frequency of the dynamic vibration absorber 1 having such a configuration is mainly a synthetic spring obtained by adding the mass of the mover 14, the spring constant of the magnetic spring portion 6 and the spring constant of the mechanical spring portion 7. It depends on the constant. The resonance frequency is preferably proportional to the square root of the composite spring constant.

(Displacement of mover)
Next, refer to FIGS. 4A and 4B for the displacement of the mover 14 and the deformation of the leaf springs 17 and 18 when the control unit 4 is operating and a current is flowing through the coils 15 and 16. I will explain it while doing it. FIG. 4A is an explanatory diagram showing the flow of magnetic flux when a current is flowing through the coils 15 and 16. FIG. 4B is an explanatory view showing the deformation of the leaf springs 17 and 18. The O mark and the X mark attached to the coils 15 and 16 in FIGS. 4A and 4B indicate the direction of the current. The O mark indicates the front side of the paper surface, and the X mark indicates the back side of the paper surface. That is, in FIGS. 4A and 4B, a current flows to the back side of the paper surface in one side portion of the coils 15 and 16 in the mover moving direction, and the other side portion of the coils 15 and 16 in the mover moving direction. In, the current is flowing to the front side of the paper.

As described above, the coils 15 and 16 are wound so that their axial directions are orthogonal to each other. Further, the winding direction of the coil 15 and the winding direction of the coil 16 are the same. Therefore, for example, when a current is flowing through the coils 15 and 16 as shown in FIG. 4A, the magnetic flux toward the other side in the orthogonal direction as shown by arrows 105, 106, 107, and 108 due to the current. Is generated. At this time, on one side in the moving element moving direction, the magnetic flux generated by the permanent magnets 12 and 13 and the magnetic flux generated by the coils 15 and 16 strengthen each other. Further, on the other side in the moving element moving direction, the magnetic flux generated by the permanent magnets 12 and 13 is weakened by the magnetic flux generated by the coils 15 and 16. As a result, a force toward one side in the moving element moving direction acts on the moving element 14 (see arrow 109 in FIG. 4A). As a result, the mover 14 is displaced in the mover moving direction. At this time, as shown in FIG. 4B, the leaf springs 17 and 18 bend to one side in the moving element moving direction.

(Switching of spring constant)
Here, the linear motor 3 has conventionally been used to displace the mover 14 within a range in which the spring constants of the leaf springs 17 and 18 are substantially constant. That is, electric power was supplied to the coils 15 and 16 so that the moving range of the mover 14 in the mover moving direction was within a predetermined range. In the first embodiment, the dynamic vibration absorber 1 changes the spring constant of the mechanical spring portion 7 and changes the spring in order to suppress vibrations of various frequencies without performing complicated control. It has a spring constant switching unit 8 (see FIG. 3) that maintains a constant (in other words, switches the spring constant). Hereinafter, a specific description will be given with reference to FIGS. 5 (a) and 5 (b). FIG. 5A is a graph showing the relationship between the amount of deformation of the leaf springs 17 and 18 and the restoring force. FIG. 5B is a graph showing the relationship between the amount of deformation of the leaf springs 17 and 18 and the spring constant. In the present embodiment, the characteristics of the leaf spring 17 and the characteristics of the leaf spring 18 are the same.

The spring constant switching unit 8 includes the control unit 4 described above, the coils 15 and 16, and the mechanical spring units 7 (leaf springs 17 and 18). The control unit 4 has a general direct current power supply, and is configured to allow a direct current to flow through the coils 15 and 16. Further, the control unit 4 is configured so that the magnitude of the direct current flowing through the coils 15 and 16 can be changed. The magnitude of the direct current flowing through the coils 15 and 16 is controlled by, for example, the control unit 4.

As shown in FIG. 5A, when the amount of deformation of the leaf springs 17 and 18 is small, the elastic restoring force of the leaf springs 17 and 18 is substantially proportional to the amount of deformation (linear region). That is, in the linear region, as shown in FIG. 5B, the spring constant, which is a proportional constant calculated from the elastic restoring force and the amount of deformation, is substantially constant. On the other hand, when the amount of deformation of the leaf springs 17 and 18 becomes large, the elastic restoring force is not proportional to the amount of deformation (non-linear region). That is, in the non-linear region, as shown in FIG. 5B, the spring constants of the leaf springs 17 and 18 increase as the amount of deformation (that is, the displacement of the mover 14 in the mover moving direction) increases. In the non-linear region, the spring constants of the leaf springs 17 and 18 continuously change according to the amount of deformation.

In the present embodiment, the spring constant of the mechanical spring portion 7 is switched by utilizing the characteristics of the leaf springs 17 and 18 as described above. Specifically, the control unit 4 applies a direct current to the coils 15 and 16 so that the amount of deformation of the leaf springs 17 and 18 is maintained at a predetermined amount of deformation in the non-linear region. In other words, the control unit 4 positions the mover 14 in a region (spring constant change region) in which the spring constants of the leaf springs 17 and 18 change according to the change in the position of the mover 14 in the mover movement direction. , Supply the coils 15 and 16. In other words, the control unit 4 supplies electric power to the coils 15 and 16 so that the reference position of the mover 14 falls within the spring constant change region. By changing the magnitude of the direct current, the position of the mover 14 in the mover moving direction is changed, and the spring constant of the mechanical spring portion 7 is changed. By maintaining the direct current at a predetermined value, the spring constant of the mechanical spring portion 7 is maintained at a predetermined value. In this way, the spring constant of the mechanical spring portion 7 is switched according to the magnitude of the current flowing through the coils 15 and 16 (in other words, the magnitude of the electric power supplied to the coils 15 and 16), and the combined spring constant becomes Can be switched. As a result, the resonance frequency of the dynamic vibration absorber 1 is switched. The synthetic spring constant can be continuously changed according to the change in the magnitude of the direct current.

As shown in the graph of FIG. 6A, the leaf springs 17 and 18 are configured so that the amount of change in the spring constant is substantially proportional to the square of the magnitude of the direct current flowing through the coils 15 and 16. It is preferable to have. That is, the leaf springs 17 and 18 may be configured so that the above-mentioned linear region does not substantially exist. When the amount of change in the spring constant is approximately proportional to the square of the magnitude of the direct current, the amount of change in the resonance frequency can be approximately proportional to the magnitude of the direct current, as shown in the graph of FIG. 6 (b). .. Therefore, the resonance frequency can be easily switched based on the magnitude of the direct current.

As described above, the combined spring constant is switched by the spring constant switching unit 8, whereby the resonance frequency of the dynamic vibration absorber 1 is switched. That is, the dynamic vibration absorber 1 does not generate a reaction force by controlling the operation of the mover 14 at any time. Therefore, vibrations of various frequencies can be suppressed without complicated control.

Further, by changing the magnitude of the electric power supplied by the control unit 4, the magnitude of the current flowing through the coils 15 and 16 is changed to change the strength of the magnetic flux, and the position is located in the spring constant change region. The position of the mover 14 can be changed. As a result, the spring constant of the mechanical spring portion 7 can be switched, and the synthetic spring constant can be switched.

Next, a modified example in which the above-described first embodiment is modified will be described. However, those having the same configuration as that of the first embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

(1) In the first embodiment, the magnitude of the current flowing through the coils 15 and 16 is controlled, but the present invention is not limited to this. When the electric resistance value of the electric circuit including the coils 15 and 16 is known, the voltage applied to the coils 15 and 16 may be controlled.

(2) In the first embodiment, one leaf spring 17 is fixed to one end of the stator 11 in the mover moving direction, and one leaf spring 18 is fixed to the other end of the stator 11 in the mover moving direction. However, it is not limited to this. For example, another leaf spring having a characteristic different from the characteristics of the spring constants of the leaf springs 17 and 18 may be arranged in parallel with the leaf springs 17 and 18.

(3) In the first embodiment, the mechanical spring portion 7 has two leaf springs 17 and 18, but the present invention is not limited to this. Only one of the leaf springs 17 and 18 may be provided.

(4) In the first embodiment, it is preferable that the amount of change in the spring constant of the mechanical spring portion 7 is substantially proportional to the square of the magnitude of the direct current flowing through the coils 15 and 16, but this is limited to this. I can't. The amount of change in the spring constant does not necessarily have to be proportional to the square of the magnitude of the direct current. That is, the amount of change in the resonance frequency does not necessarily have to be proportional to the magnitude of the direct current.

<Second Embodiment>
Next, the dynamic vibration absorber 1a according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8 (a) and 8 (b). However, those having the same configuration as that of the first embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate. FIG. 7 is a schematic view of the linear motor 3a according to the second embodiment. 8 (a) and 8 (b) are explanatory views showing the operation of the linear motor 3a.

The linear motor 3a of the dynamic vibration absorber 1a is provided with the magnetic spring portion 6 described in the first embodiment. Further, instead of the mechanical spring portion 7 described in the first embodiment, a mechanical spring portion 7a having the following configuration is provided. As shown in FIG. 7, the mechanical spring portion 7a includes leaf springs 21, 22 (second leaf spring of the present invention), and leaf springs 23, 24, in addition to the leaf springs 17 and 18 described above. Further, the spring constant switching unit 8a of the dynamic vibration absorber 1a includes the control unit 4 described above, the coils 15 and 16, and the mechanical spring unit 7a.

The leaf springs 17, 21, and 23 are provided side by side from the other side to one side in the mover moving direction in this order, and are arranged apart from each other. Further, the leaf springs 18, 22, and 24 are provided side by side from the other side to one side in the mover moving direction in this order, and are arranged apart from each other. Like the leaf springs 17 and 18, both ends of the leaf springs 21 to 24 in the orthogonal direction are fixed to the stator 11. Unlike the leaf springs 17 and 18, the leaf springs 21 to 24 are not fixed to the shaft 19 that supports the mover 14, but are provided with a gap from the shaft 19.

In the dynamic vibration absorber 1a having the above configuration, when a direct current flows through the coils 15 and 16 by the control unit 4 and the mover 14 moves to one side in the mover moving direction, the state of the mechanical spring part 7a is as follows. It changes to. When the direct current is small, the leaf springs 17 and 18 are not in contact with the leaf springs 21 and 22 (first state), and the elastic restoring force of the leaf springs 17 and 18 acts on the mover 14. That is, the spring constant of the mechanical spring portion 7a is exclusively determined by the spring constants of the leaf springs 17 and 18. On the other hand, by passing a larger direct current than in the first state, as shown in FIG. 8A, the central portion of the leaf spring 17 in the orthogonal direction is brought into contact with the leaf spring 21, and the leaf spring 18 is in the orthogonal direction. The central portion can be brought into contact with the leaf spring 22 (second state). That is, the leaf spring 17 and the leaf spring 21 can be moved integrally, and the leaf spring 18 and the leaf spring 22 can be moved integrally. At this time, the resultant force of the elastic restoring force by the leaf springs 17, 18, 21, and 22 acts on the mover 14. That is, the number of leaf springs that apply an elastic restoring force to the mover 14 in the second state is larger than the number of leaf springs that apply an elastic restoring force to the mover 14 in the first state. As a result, the spring constant of the mechanical spring portion 7a in the second state can be made larger than the spring constant of the mechanical spring portion 7a in the first state. In this way, the spring constant of the mechanical spring portion 7a can be significantly different between when the leaf springs 17 and 18 are not in contact with the leaf springs 21 and 22 and when they are in contact with the leaf springs 21 and 22. .. Therefore, the spring constant of the mechanical spring portion 7a can be effectively switched. Further, when the direct current is further large, the mover 14 further moves to one side in the mover moving direction. As a result, as shown in FIG. 8B, the leaf spring 21 comes into contact with the leaf spring 23, and the leaf spring 22 comes into contact with the leaf spring 24. As a result, the spring constant can be further increased. The leaf springs 17 and 18 may be used in the non-linear region in the first state as in the first embodiment described above.

Next, a modified example in which the above-described second embodiment is modified will be described. However, those having the same configuration as that of the second embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

(1) In the second embodiment, the mechanical spring portion 7a has leaf springs 17, 18, 21, 22, 23, 24 (that is, a total of 6 leaf springs), but the number of leaf springs is this. Not limited to. That is, the number of leaf springs may be larger. On the contrary, the leaf springs 23 and 24 may not be provided, and further, only one of the leaf springs 21 and 22 may be provided.

(2) In the second embodiment, for example, when the leaf springs 17 and 18 are in a boundary state of whether or not they come into contact with the leaf springs 21 and 22, when the mover 14 is vibrated by an external force, the plate Contact and separation between the springs 17 and 18 and the leaf springs 21 and 22 may occur repeatedly. As a result, the spring constant may fluctuate unintentionally, or the collision noise between the leaf springs may be repeatedly generated to cause noise. In order to avoid this, the control unit 4 (see FIG. 1) may control the linear motor 3 as follows. For example, the information on the magnitude of the current flowing through the coils 15 and 16 when the leaf springs 17 and 18 are surely in contact with the leaf springs 21 and 22 (that is, the second state is surely maintained) is controlled. Part 4 may remember it. Then, for example, when switching the state of the leaf springs 17 and 18 from the first state to the second state, the control unit 4 may cause a current of a stored size to flow through the coils 15 and 16. In this way, it is possible to avoid the state where the leaf springs 17 and 18 come into contact with the leaf springs 21 and 22 or not.

(3) In order to solve the problem of unintended fluctuation of the spring constant and the problem of noise described in the modified example of (2) above, the linear motor 3b of the dynamic vibration absorber 1b described later has the following configuration. You may. Hereinafter, description will be made with reference to FIGS. 9 and 10 (a) and 10 (b). FIG. 9 is a schematic view of the linear motor 3b. 10 (a) and 10 (b) are explanatory views showing the operation of the linear motor 3b. In FIGS. 9 and 10 (a) and 10 (b), the other side portion of the shaft 19 and the leaf springs 18, 22 and 24 in the moving element moving direction are omitted for simplification of description. Further, in FIGS. 9 and 10 (a) and 10 (b), in order to make it easier to see the magnetic poles of the permanent magnets 25 and 26 described later, the distance between the leaf springs 17, 21 and 23 is shown larger than that in FIG. 8 and the like. There is. However, such a difference in the drawings does not necessarily mean that the configuration of the mechanical spring portion 7a described above and the configuration of the mechanical spring portion 7b described later are different from each other.

The linear motor 3b of the Tuned Mass Damper 1b has a magnetic spring portion 6b and a mechanical spring portion 7b. The configuration of the mechanical spring portion 7b is the same as the configuration of the mechanical spring portion 7a. The magnetic spring portion 6b has permanent magnets 25 and 26 instead of the permanent magnets 12 and 13 described above, and has a mover 27 instead of the mover 14. The permanent magnets 25 and 26 are multi-pole magnetized. In the example of FIG. 9, on the permanent magnets 25 and 26, five north poles and five south poles are alternately arranged in the moving element moving direction. Hereinafter, of the permanent magnets 25 and 26, the portions corresponding to the pair of magnetic poles located at the central portion in the moving element moving direction are referred to as the first portions 25a and 26a, respectively. In line with this, the length of the mover 27 in the mover moving direction is shorter than the length of the first portions 25a and 26a in the mover moving direction. Further, the portions arranged adjacent to one side of the first portions 25a and 26a in the moving element moving direction are referred to as the second portions 25b and 26b, respectively. The distance between the center of the first portions 25a and 26a in the mover moving direction and the center of the second portions 25b and 26b in the mover moving direction is substantially equal to the distance between the leaf spring 17 and the leaf spring 21 in the mover moving direction. .. Further, the portions arranged adjacent to one side of the second portions 25b and 26b in the moving element moving direction are referred to as the third portions 25c and 26c, respectively.

In such a configuration, when no current is flowing through the coils 15 and 16, the position of the mover 27 in the mover moving direction is stably within the extending range of the first portions 25a and 26a in the mover moving direction. It fits. This position is defined as the first stable position. On the other hand, when a large current flows through the coils 15 and 16, the mover 27 can move vigorously in the mover moving direction. As a result, for example, as shown in FIG. 10A, the mover 27 moves within the extension range of the second portions 25b and 26b in the mover movement direction, and the position is stabilized (second stable position). At this time, the leaf spring 17 surely contacts the leaf spring 21, and the spring constant is surely switched. In this way, the spring constant can be reliably switched by generating the so-called overcoming from the first stable position to the second stable position. Further, as shown in FIG. 10B, by passing a larger current through the coils 15 and 16 when the mover 27 is located at the second stable position, the mover 27 is moved into the third portions 25c and 26c. The position can be stabilized by moving the coil within the extension range in the moving direction of the mover (third stable position).

<Third Embodiment>
Next, the dynamic vibration absorber 1c according to the third embodiment of the present invention will be described with reference to FIGS. 11 and 12 (a) and 12 (b). However, those having the same configuration as those of the first to second embodiments are designated by the same reference numerals and the description thereof will be omitted as appropriate. FIG. 11 is a schematic view of the linear motor 3c according to the third embodiment. 12 (a) and 12 (b) are explanatory views showing the operation of the linear motor 3c.

The linear motor 3c of the Tuned Mass Damper 1c has a magnetic spring portion 6c and the mechanical spring portion 7 described above. The linear motor 3c has a spring constant switching portion 8c so that the spring constant of the magnetic spring portion 6c can be changed. The magnetic spring portion 6c has a stator 31, permanent magnets 32 and 33, and a mover 34. Further, the spring constant switching unit 8c has a stator 31, permanent magnets 32 and 33, a mover 34, and the coils 15 and 16 described above.

As shown in FIG. 11, the stator 31 has convex portions 31a and 31b instead of the convex portions 11a and 11b described above. The permanent magnets 32 and 33 are fixed to the convex portions 31a and 31b, respectively, and have the same characteristics as the above-mentioned permanent magnets 12 and 13. The surface of the convex portion 31a to which the permanent magnet 32 is fixed is inclined toward one side in the mover moving direction and the other side in the orthogonal direction. As a result, the facing surface 32a of the permanent magnet 32 facing the mover 34 is inclined toward one side in the mover moving direction toward the other side in the orthogonal direction. The surface of the convex portion 31b to which the permanent magnet 33 is fixed is inclined toward one side in the mover moving direction and one side in the orthogonal direction. As a result, the facing surface 33a of the permanent magnet 33 facing the mover 34 is inclined so as to move toward one side in the mover moving direction and toward one side in the orthogonal direction. That is, the distance between the facing surface 32a and the facing surface 33a in the orthogonal direction becomes narrower toward one side in the mover moving direction.

As shown in FIG. 11, the size of the mover 34 becomes smaller in the orthogonal direction toward one side in the mover moving direction. As an example, the mover 34 is formed in a truncated cone shape. The mover 34 and the permanent magnet 32 are arranged so as to face each other in the first crossing direction orthogonal to the facing surface 32a. The mover 34 and the permanent magnet 33 are arranged so as to face each other in the second crossing direction orthogonal to the facing surface 33a. The first crossing direction and the second crossing direction correspond to the crossing direction of the present invention. The mover 34 is located at a predetermined position (first position) in the mover moving direction when no current is flowing through the coils 15 and 16. The gap between the mover 34 and the permanent magnet 32 in the first crossing direction and the gap between the mover 34 and the permanent magnet 33 in the second crossing direction (hereinafter, simply "the gap between the mover 34 and the permanent magnets 32 and 33". Is a predetermined first gap when the mover 34 is located at the first position. When an external force is applied to the mover 34 in this state, a restoring force (first restoring force) for returning the mover 34 to the first position acts on the mover 34 by the magnetic spring portion 6c. That is, when no current is flowing through the coils 15 and 16, the first position is the reference position of the mover 34.

In the linear motor 3c having the above configuration, when a direct current is passed through the coils 15 and 16 to change the reference position of the mover 34, the size of the gap between the mover 34 and the permanent magnets 32 and 33 changes. .. For example, when the mover 34 moves to the second position (see FIG. 12A), which is one side of the first position in the mover moving direction, the gap becomes a second gap smaller than the first gap. .. As a result, the magnetic flux flowing between the permanent magnets 32 and 33 and the mover 34 is strengthened, so that the restoring force (second restoring force) for returning the mover 34 to the second position is stronger than the first restoring force. .. That is, the spring constant of the magnetic spring portion 6c when the reference position of the mover 34 is the second position is larger than the spring constant of the magnetic spring portion 6c when the reference position of the mover 34 is the first position. .. On the other hand, when the mover 34 moves to the third position (see FIG. 12B), which is on the opposite side of the first position in the mover moving direction, the gap becomes a third gap larger than the first gap. .. As a result, the spring constant of the magnetic spring portion 6c when the reference position of the mover 34 is the third position is smaller than the spring constant of the magnetic spring portion 6c when the reference position of the mover 34 is the first position. Become. As described above, the spring constant of the magnetic spring portion 6c can be changed by changing the size of the gap between the mover 34 and the permanent magnets 32 and 33. This makes it possible to switch the synthetic spring constant. The synthetic spring constant can be continuously changed according to the change in the reference position of the mover 34.

Next, a modified example in which the above-described third embodiment is modified will be described. However, those having the same configuration as that of the third embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

(1) In the linear motor 3c described above, the leaf springs 17 and 18 may be used in a non-linear region as in the first embodiment described above.

(2) The linear motor 3c may have, for example, the mechanical spring portion 7a described in the second embodiment instead of the mechanical spring portion 7.

<Fourth Embodiment>
Next, the dynamic vibration absorber 1d according to the fourth embodiment of the present invention will be described with reference to FIGS. 13 (a) and 13 (b). However, those having the same configuration as those of the first to third embodiments are designated by the same reference numerals and the description thereof will be omitted as appropriate. 13 (a) and 13 (b) are schematic views of the dynamic vibration absorber 1d according to the fourth embodiment.

The dynamic vibration absorber 1d includes a linear motor 3 similar to that of the first embodiment, and a cam device 40 as a spring constant switching unit. The cam device 40 is configured to change the size of the gap between the mover 14 and the permanent magnets 12 and 13. The cam device 40 has a cam 41 and a motor 42. The cam 41 is arranged so that, for example, the peripheral surface of the cam 41 contacts one end surface of the stator 11 in the orthogonal direction. The diameter of the cam 41 changes smoothly depending on, for example, the position of the cam 41 in the circumferential direction. The cam 41 is fixed to a rotation shaft 43 extending in a direction (vertical to the paper surface) orthogonal to both the mover moving direction and the orthogonal direction. The cam 41 and the rotating shaft 43 are rotationally driven by the motor 42. The motor 42 is, for example, a known stepping motor, and is configured to be rotatable in the forward and reverse directions.

In the dynamic vibration absorber 1d as described above, for example, when the small diameter portion of the cam 41 is in contact with the stator 11 as shown in FIG. 13 (a), and when the cam is in contact with the stator 11, for example, as shown in FIG. 13 (b). The size of the gap between the mover 14 and the permanent magnets 12 and 13 differs depending on whether the large diameter portion of 41 is in contact with the stator 11. That is, when the small diameter portion of the cam 41 is in contact with the stator 11, the gap is relatively large because the amount of the stator 11 pushed by the cam 41 is small. That is, by maintaining the state in which the small diameter portion of the cam 41 is in contact with the stator 11, the state in which the spring constant of the magnetic spring portion 6 is relatively small can be maintained. On the other hand, when the motor 42 operates and the large diameter portion of the cam 41 comes into contact with the stator 11, the stator 11 is greatly pushed by the cam 41, so that the gap becomes smaller. That is, by maintaining the state in which the large diameter portion of the cam 41 is in contact with the stator 11, the state in which the spring constant of the magnetic spring portion 6 is large can be maintained. As described above, the spring constant of the magnetic spring portion 6 can be switched by changing the size of the gap between the mover 14 and the permanent magnets 12 and 13. In the fourth embodiment, the coils 15 and 16 do not necessarily have to be provided.

Next, a modified example in which the above-described fourth embodiment is modified will be described. However, those having the same configuration as that of the fourth embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

(1) The configuration for switching the size of the gap between the mover 14 and the permanent magnets 12 and 13 is not limited to the cam device 40 described above. For example, instead of the cam device 40, the size of the gap may be changed by a ball screw mechanism (not shown).

<Fifth Embodiment>
Next, the dynamic vibration absorber 1e according to the fifth embodiment of the present invention will be described with reference to FIGS. 14 and 15 (a) and 15 (b). However, those having the same configuration as those of the first to fourth embodiments are designated by the same reference numerals and the description thereof will be omitted as appropriate. FIG. 14 is a schematic view of the dynamic vibration absorber 1e according to the fifth embodiment. 15 (a) and 15 (b) are explanatory views showing the magnetic flux passing through the magnetic spring portion 6e, which will be described later.

As shown in FIG. 14, the dynamic vibration absorber 1e has a magnetic spring portion 6e and the mechanical spring portion 7 described above. The magnetic spring portion 6e has the above-mentioned mover 14, the stator 51, and the permanent magnets 52, 53, 54, 55. Further, the dynamic vibration absorber 1e has coils 56 and 57 as spring constant switching portions 8e. Unlike the linear motor, the dynamic vibration absorber 1e is not configured to move the mover 14 by passing an electric current through the coils 56 and 57. The dynamic vibration absorber 1e is configured to switch the spring constant of the magnetic spring portion 6e by passing an electric current through the coils 56 and 57 to generate a magnetic flux and changing the restoring force acting on the mover 14. Details will be described later).

A recess 51a is formed in the central portion of the stator 51 in the direction of movement of the mover on one side in the orthogonal direction. In other words, the convex portion 51b is formed on one side of the concave portion 51a in the moving direction of the mover, and the convex portion 51c is formed on the other side. A permanent magnet 52 (first permanent magnet of the present invention) is fixed to the other end of the convex portion 51b in the orthogonal direction. A permanent magnet 53 (second permanent magnet of the present invention) is fixed to the other end of the convex portion 51c in the orthogonal direction. The permanent magnets 52 and 53 are arranged so that the directions of the magnetic poles in the orthogonal direction are opposite to each other. For example, when one side portion of the permanent magnet 52 in the orthogonal direction is the south pole and the other side portion is the north pole, one side portion of the permanent magnet 53 in the orthogonal direction is the north pole and the other side portion is the south pole. Similarly, a recess 51d is formed in the central portion of the other side portion of the stator 51 in the orthogonal direction in the mover moving direction. A convex portion 51e is formed on one side of the concave portion 51d in the moving direction of the mover, and a convex portion 51f is formed on the other side. A permanent magnet 54 is fixed to one side end of the convex portion 51e in the orthogonal direction, and a permanent magnet 55 is fixed to one side end of the convex portion 51f in the orthogonal direction. The orientation of the magnetic poles of the permanent magnet 54 is the same as the orientation of the magnetic poles of the permanent magnet 52. The orientation of the magnetic poles of the permanent magnet 55 is the same as the orientation of the magnetic poles of the permanent magnet 53. When no current is flowing through the coils 56 and 57, for example, the magnetic flux is flowing in the directions shown by arrows 111 to 116 in FIG. Specifically, the magnetic flux flows counterclockwise in FIG. 14 in the order of the permanent magnet 52, the mover 14, the permanent magnet 53, and the stator 51. Further, the magnetic flux flows counterclockwise in FIG. 14 in the order of the permanent magnet 54, the stator 51, the permanent magnet 55, and the mover 14.

The coil 56 is wound around a central portion (that is, a recess 51a) in the mover moving direction of one side portion of the stator 51 in the orthogonal direction. The axial direction of the coil 56 is substantially parallel to the moving direction of the mover. The coil 57 is wound around the central portion (that is, the recess 51d) in the mover moving direction of the other side portion of the stator 51 in the orthogonal direction. The axial direction of the coil 57 is substantially parallel to the moving direction of the mover. The winding direction of the coil 56 and the winding direction of the coil 57 are opposite to each other. The coils 56 and 57 are electrically connected to the control unit 4.

In the dynamic vibration absorber 1e as described above, the above-mentioned magnetic flux can be strengthened or weakened by passing a current through the coils 56 and 57. Specifically, it is as follows. That is, by passing a current in a predetermined direction (first direction), the counterclockwise magnetic flux in FIG. 15A is generated (see arrows 121 to 123 and arrows 124 to 126 in FIG. 15A). ). By strengthening this magnetic flux and the magnetic flux generated by the permanent magnets 52 to 55 (see FIG. 15A), the restoring force of the magnetic spring portion 6e acting on the mover 14 becomes stronger (that is, the spring). The constant increases). Further, by passing a current in the direction opposite to the first direction (second direction), the clockwise magnetic flux in FIG. 15 (b) is generated (arrows 131 to 133 and arrows in FIG. 15 (b). 134-136). This magnetic flux weakens the magnetic flux generated by the permanent magnets 52 to 55, so that the restoring force of the magnetic spring portion 6e acting on the mover 14 is weakened (that is, the spring constant is reduced). As described above, the spring constant of the magnetic spring portion 6e can be switched. In the fifth embodiment, the orthogonal direction corresponds to the intersecting direction of the present invention, but the present invention is not limited to this.

Next, a modified example in which the above-described fifth embodiment is modified will be described. However, those having the same configuration as that of the fifth embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

(1) The method of winding the coil is not limited to that described above. For example, as shown in FIGS. 16A and 16B, in the spring constant switching portion 8f for switching the spring constant of the magnetic spring portion 6f of the dynamic vibration absorber 1f, the convex portions 51b, 51c, 51e, 51f of the stator 51 The coils 61, 62, 63, and 64 may be wound around the coil, respectively. The axial direction of the coils 61 to 64 is along the orthogonal direction. The winding directions of the coils 61 and 63 are the same, and the winding directions of the coils 62 and 64 are opposite to the winding directions of the coils 61 and 63. The coils 61 to 64 are electrically connected to each other. Even in such a configuration, by passing a current in a predetermined direction, it is possible to generate magnetic fluxes that strengthen each other with the magnetic fluxes generated by the permanent magnets 52 to 55 (see arrows 141 to 144 in FIG. 16A). ). Further, by passing an electric current in the direction opposite to the predetermined direction, it is possible to generate a magnetic flux that weakens the magnetic flux generated by the permanent magnets 52 to 55 (see arrows 151 to 154 in FIG. 16B).

1 Dynamic vibration absorber 2 Vibration damping object 4 Control unit 6 Magnetic spring part 7 Mechanical spring part 8 Spring constant switching part 11 Stator 12 Permanent magnet 13 Permanent magnet 14 Movable element 15 Coil 16 Coil 17 Leaf spring (1st leaf spring)
18 Leaf spring (1st leaf spring)
21 leaf spring (second leaf spring)
22 leaf spring (second leaf spring)
57 coil 58 coil

Claims (5)

A dynamic vibration absorber that is attached to a vibration damping object and suppresses vibration of the vibration damping object.
A magnetic spring portion having a stator, a permanent magnet attached to the stator, and a mover provided so as to be reciprocally movable in a predetermined direction by a magnetic force generated by at least the magnetic flux generated by the permanent magnet.
A mechanical spring portion having a first leaf spring that is fixed to the stator and has the mover movably attached in the predetermined direction and is deformable in the predetermined direction.
A dynamic vibration absorber including a spring constant switching unit that switches a synthetic spring constant determined by the spring constant of the magnetic spring portion and the spring constant of the mechanical spring portion. The spring constant switching unit is
A coil that generates magnetic flux to change the position of the mover in the predetermined direction when an electric current is flowing.
It has a control unit that supplies electric power to the coil.
A current is passed through the coil by the control unit, and the mover is positioned in a spring constant change region in which the spring constant of the first leaf spring changes according to a change in the position of the mover in the predetermined direction. The dynamic vibration absorber according to claim 1, wherein the spring constant of the mechanical spring portion is switched according to the magnitude of the current flowing through the coil. The mechanical spring portion is
It has a second leaf spring fixed to the stator, arranged side by side with the first leaf spring in the predetermined direction, and deformable in the predetermined direction.
The spring constant switching unit is
A coil that generates magnetic flux to change the position of the mover in the predetermined direction when an electric current is flowing.
A control unit that supplies electric power to the coil is provided.
Depending on the magnitude of the power supplied to the coil by the control unit, the first state in which the first leaf spring is not in contact with the second leaf spring and the first leaf spring are the second leaf spring. The dynamic vibration absorber according to claim 1 or 2, wherein the spring constant of the mechanical spring portion is switched by changing the state of the mechanical spring portion with and from the second state in contact with the mechanical spring portion. The mover and the permanent magnet are arranged so as to face each other in an intersecting direction intersecting the predetermined direction.
The spring constant switching unit is
The dynamic vibration absorber according to any one of claims 1 to 3, wherein the spring constant of the magnetic spring portion is switched by changing the size of the gap between the mover and the permanent magnet in the crossing direction. .. The stator is
As the permanent magnet
A first permanent magnet arranged so that a magnetic pole having a first polarity faces one end of the mover in the predetermined direction in an intersecting direction intersecting the predetermined direction.
In the crossing direction, there is a second permanent magnet arranged so that a magnetic pole having a second polarity opposite to the first polarity faces the other end of the mover in the predetermined direction. And
The spring constant switching unit is
To generate a magnetic flux that strengthens or weakens both the magnetic flux flowing between the first permanent magnet and the mover and the magnetic flux flowing between the second permanent magnet and the mover when an electric current is flowing. The dynamic vibration absorber according to claim 1, further comprising a coil for switching the spring constant of the magnetic spring portion.

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