Vibration-damping device

Abstract

[Problem] To provide a vibration-damping device that uses magnetic force, wherein restriction in the movement amount of a member that exerts a magnetic force is suppressed. [Solution] A vibration-damping device comprising an inner member and an outer member that are configured so as to be reciprocally movable relative to each other along a first direction. The inner member is disposed inside the outer member in a second direction orthogonal to the first direction and is provided with an end member that is configured from a magnetic body and disposed so as to face a magnetic pole of the outer member in the second direction. The outer member is provided with a magnetic device configured so as to attract the end member in an equilibrium state, and movement of the end member and the magnetic device in the second direction is restricted so as to prevent contact between the end member and the magnetic device.

Description

Vibration damping device

[0001] The present invention relates to a vibration damping device that utilizes magnetic force.

[0002] Conventionally, the invention relates to a magneto-resistive device including a base, an upper annular permanent magnet, a lower annular permanent magnet, a connecting rod, and a central permanent magnet, wherein a metal conductor sleeve is connected to the upper surface of the base, the metal conductor sleeve being a hollow metal cylinder, the base sealing the lower end surface of the metal conductor sleeve, the upper annular permanent magnet and the lower annular permanent magnet having the same shape and both being hollow rings, the upper annular permanent magnet and the lower annular permanent magnet being fitted into an upper annular bushing and a lower annular bushing, respectively, the upper annular bushing and the lower annular bushing being connected to the upper end and the lower end of the inner wall of the metal conductor sleeve, the upper annular permanent magnet, the lower annular permanent magnet, and the metal conductor sleeve being concentric in the axial direction, and the upper annular permanent magnet and the lower annular permanent magnet being fitted into an upper annular bushing and a lower annular bushing, respectively ... concentric in the axial direction, A one-degree-of-freedom magnetic vibration isolation device is known, characterized in that the magnetic poles on the opposing surfaces of the annular permanent magnet and the lower annular permanent magnet have opposite polarities, the axis of the connecting rod is coaxial with the central axis of the metal conductor sleeve, the central permanent magnet is a hollow ring that is concentrically fitted over and fixed to the connecting rod, the upper end of the connecting rod passes through the central hole of the upper annular permanent magnet, the central permanent magnet is located between the upper and lower annular permanent magnets and can move axially together with the connecting rod between the upper and lower annular permanent magnets, and the magnetic poles on the opposing surfaces of the central permanent magnet and the upper annular permanent magnet have opposite polarities, and the magnetic poles on the opposing surfaces of the central permanent magnet and the lower annular permanent magnet have opposite polarities (see, for example, Patent Document 1).

[0003] The single-degree-of-freedom magnetic vibration isolation device disclosed in Cited Document 1 "can generate both static and dynamic magneto-static forces without requiring an energy supply and with high reliability. The static magneto-static force is realized by the mutual attraction of opposite poles of a permanent magnet, while the dynamic magneto-static force is realized by eddy current damping generated by the relative motion of a metal conductor sleeve and a permanent magnet. The magnitude of the static magneto-static force is related only to displacement, and the magnetic force exists even when the device of the present invention is stationary, so it can be considered a type of rigid force. The eddy current damping is related only to the relative motion speed, and exists only when motion occurs in the magnetic mechanism, so it can be considered a type of viscous damping force." Furthermore, this single-degree-of-freedom magnetic vibration isolation device "can be used in parallel with passive vibration isolation structures such as rigid coil springs or air springs to reduce the increase in amplitude value at the natural frequency without affecting the high-frequency damping performance of the passive vibration isolation system, thereby effectively improving the passive vibration isolation performance of the original system."

[0004] Patent No. 6317822

[0005] The one-degree-of-freedom magnetic vibration damping device disclosed in Patent Document 1 "opposes the polarity of the magnetic poles on the opposing surfaces of the upper and lower annular permanent magnets" and "the central permanent magnet is located between the upper and lower annular permanent magnets and moves axially between the upper and lower annular permanent magnets together with the connecting rod." Therefore, when the central permanent magnet moves in either the up or down direction from the equilibrium state, the upper or lower annular permanent magnet is present on its extension line, which limits the amount of movement of the central permanent magnet.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a vibration damping device that uses magnetic force and minimizes restrictions on the amount of movement of the member that applies the magnetic force.

[0007] The vibration damping device of the present invention is a vibration damping device comprising an inner member and an outer member configured to be able to move back and forth relative to each other along a first direction, wherein the inner member is arranged inside the outer member in a second direction perpendicular to the first direction, and comprises an end member made of a magnetic material arranged opposite the magnetic pole of the outer member in the second direction, the outer member comprises a magnetic device configured to attract the end member in an equilibrium state, and movement of the end member and the magnetic device in the second direction is restricted so as not to come into contact.

[0008] According to the above invention, a magnetic force in an attractive direction is generated between the inner member and the outer member, and since the movement paths of the inner member and the outer member do not intersect, the movement of the inner member and the outer member is not restricted by each other.

[0009] 5 is a schematic diagram of the main components of a vibration damping device 100 according to a first embodiment. It is an enlarged view of the first end 13 and the magnetic pole 21a of the magnetic device 21 in FIG. 1. It is a schematic diagram showing a state in which the inner member 10 of the vibration damping device 100 shown in FIG. 1 has moved in the z direction. It is a diagram showing the relationship between the movement distance of the inner member 10 of the vibration damping device 100 according to the first embodiment and the generated magnetic force. It is a schematic diagram of the main components of a vibration damping device 100A which is a modified example of the vibration damping device 100 according to the first embodiment. It is a diagram showing the relationship between the movement distance of the inner member 10 of the vibration damping device 100A according to the modified example shown in FIG. 5 and the generated magnetic force. It is an example of a schematic diagram of the vibration damping devices 100 and 100A according to the first embodiment when viewed from above (as viewed from the z direction). It is another example of a schematic diagram of the vibration damping devices 100 and 100A according to the first embodiment when viewed from above (as viewed from the z direction). It is a schematic diagram of the main components of a vibration damping device 100B which is a modified example of the vibration damping device 100 according to the first embodiment. 11 is a schematic diagram of the main components of a vibration damping device 100C that is a modified example of the vibration damping device 100 according to embodiment 1. FIG. 12 is a schematic diagram of the main components of a vibration damping device 200 according to embodiment 2. FIG. 13 is a diagram showing the relationship between the movement distance of the inner member 10 and the generated load, and the relationship between the expansion and contraction amount of the elastic member 30 and the generated load, in the vibration damping device 100 shown in FIG. 1. FIG. 14 is a diagram showing the relationship between the movement distance of the inner member 10 and the generated magnetic force in the vibration damping device 200 according to embodiment 2. FIG. 15 is a schematic diagram of the main components of a vibration damping device 300 according to embodiment 3. FIG. 16 is a schematic diagram of the state in which the inner member 10 has moved in the z2 direction from the vibration damping device 300 in the state shown in FIG. 15. FIG. 17 is a schematic diagram of the main components of a vibration damping device 100D that is a modified example in which the second end 12 is removed from the vibration damping device 100 according to embodiment 1.

[0010] The preferred embodiments of the vibration damping device of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below are preferred specific examples of the present invention, and therefore various technically preferable limitations are applied, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0011] Embodiment 1. <Vibration Damping Device 100> Figure 1 is a schematic diagram of the main configuration of a vibration damping device 100 according to Embodiment 1. The vibration damping device 100 shown in Figure 1 includes an inner member 10 that is movable in the z-direction and a fixed outer member 20. The vibration damping device 100 is configured such that, for example, the inner member 10 is connected to another structure and acts to suppress displacement of the structure in the z-direction using magnetic force. The vibration damping device 100 is used, for example, to damp vibrations in automobile dampers, seismic isolation devices for buildings, or vibration control devices for machines. Note that, although an example in which the inner member 10 moves in the z-direction is described in Embodiment 1, the vibration damping device 100 may have any structure as long as the inner member 10 and the outer member 20 can move relative to each other in the z-direction.

[0012] The vibration damping device 100 has, for example, an outer member 20 formed in a cylindrical shape. The outer member 20 surrounds the inner member 10 from a direction perpendicular to the z direction. The outer member 20 includes a magnetic device 21. In a cross section parallel to the z direction, the magnetic device 21 has a pair of magnetic poles 21a and 21b arranged along the z direction. In FIG. 1 , the magnetic devices 21A and 21B are arranged so that the south pole is located at the end in the z1 direction and the north pole is located at the end in the z2 direction. The magnetic devices 21A and 21B may be integrated magnetic devices or may be separate magnetic devices. The z direction may be referred to as the first direction, and the direction perpendicular to the z direction may be referred to as the second direction.

[0013] The inner member 10 is disposed inside the outer member 20 in a direction (x-y direction) perpendicular to the z-direction. The inner member 10 has a first end 13 and a second end 12 disposed apart in the z-direction. The first end 13 and the second end 12 are each made of a magnetic material. In FIG. 1 , the first end 13 and the second end 12 are each made of a magnet, but they may be made of a soft magnetic material such as iron or nickel. In other words, the first end 13 and the second end 12 may have no or almost no magnetic force themselves but may be attracted to the magnetic device 21.

[0014] The first end 13 and the second end 12 are connected in the z direction by a connecting member 11. The connecting member 11 is a member for maintaining a constant distance between the first end 13 and the second end 12. The connecting member 11 may be made of a non-magnetic material such as a resin material, or a metal containing a magnetic material. The inner member 10 may also include structures supporting the first end 13 and the second end 12 at their ends in the z direction, and the structures may be connected in the z direction by the connecting member 11. The structures supporting the first end 13 and the second end 12 may be members formed integrally with the connecting member 11, or may be separate members connected by means of bolts or welding. The first end 13 and the second end 12 may be collectively referred to as end members. In other words, the first end 13 and the second end 12 constitute end members.

[0015] The first end 13 and the second end 12 are configured to be attracted to the magnetic pole 21a or 21b of the magnetic device 21 in the balanced state shown in Fig. 1. The tip 13a of the first end 13 is configured to be attracted to the magnetic pole 21a of the magnetic device 21, and is the north pole in the example shown in Fig. 1. The tip 12a of the second end 12 is configured to be attracted to the magnetic pole 21b of the magnetic device 21, and is the south pole in the example shown in Fig. 1.

[0016] Although structures supporting the inner member 10 and the outer member 20 are not shown in FIG. 1 , the vibration damping device 100 may include structures supporting the inner member 10 and the outer member 20. Alternatively, since the inner member 10 is configured to be attracted to the outer member 20, a spacer or bearing may be provided to maintain a predetermined distance between the inner member 10 and the outer member 20 so that the tip 13 a of the first end 13 and the tip 12 a of the second end 12 do not come into contact with the magnetic poles 21 a and 21 b. Furthermore, the distance between the inner member 10 and the outer member 20 in a direction perpendicular to the z-direction may be dynamically controlled. The magnetic force of attraction can be controlled by dynamically controlling the distance between the end members (the first end 13 and the second end 12) and the magnetic device 21 in a direction perpendicular to the z-direction. This allows the damping force of the vibration damping device 100 to be controlled.

[0017] Figure 2 is an enlarged view of the first end 13 and the magnetic pole 21a of the magnetic device 21 in Figure 1. Figure 2(a) schematically illustrates the magnetic force generated at the first end 13. Figure 2(b) schematically illustrates the distribution of magnetic field lines of the magnetic device 21. The operating principle of the vibration damping device 100 will be explained using Figures 1 and 2.

[0018] The tip 13a of the first end 13 of the inner member 10 is positioned to face the magnetic pole 21a of the magnetic device 21 in the x direction. The tip 13a of the first end 13 is a north pole and receives a magnetic force in an attractive direction along the magnetic field lines generated by the magnetic pole 21a of the magnetic device 21 shown in FIG. 2(b). Therefore, as shown in FIG. 2(a), a magnetic force fa is generated at the end of the end surface of the tip 13a on the z2 side, and a magnetic force fb is generated at the end of the end surface of the tip 13a on the z1 side. These magnetic forces fa and fb can be resolved into x-direction component forces xa and xb and z-direction component forces za and zb. FIG. 2(a) shows the equilibrium state (initial position) of the vibration damping device 100, in which the z-direction component forces za and zb are balanced. The x-direction component forces xa and xb balance with the magnetic force generated between the tip 13a of the first end 13 located on the x2 side shown in FIG. 1 and the magnetic pole 21a of the magnetic device 21A.

[0019] The tip 13a of the first end 13 of the inner member 10 and the tip 12a of the second end 12 are subjected to component forces as shown in FIG. 2( a), and therefore the magnetic forces are balanced in the z direction and in a direction perpendicular to the z direction (the x direction in FIG. 2), and the vibration damping device 100 is stationary. This stationary state of the vibration damping device 100 is called an equilibrium state. If the magnetic forces generated between the inner member 10 and the outer member 20 were ideally balanced, the inner member 10 and the outer member 20 could maintain a state of equilibrium even without a support structure. However, since the vibration damping device 100 is connected to an external structure and receives external forces, it has a structure that limits movement of at least the inner member 10 and the outer member 20 in a direction perpendicular to the z direction. The inner member 10 and the outer member 20 may be supported by support members such as bearings, limiting movement in a direction perpendicular to the z direction, or one of them may be fixed. In either case, the inner member 10 and the outer member 20 are configured to be able to move relative to each other at least in the z direction.

[0020] 2(a) shows a state of equilibrium in which the center of the z-direction width of the tip 13a of the first end 13 of the inner member 10 and the tip surface of the magnetic device 21B of the outer member 20 are aligned in the z-direction. However, for example, when the inner member 10 is subjected to an external force such as gravity, the equilibrium state shifts in the direction of gravity. At this time, the load received by the inner member 10 in the direction of gravity and the magnetic forces generated at the first end 13 and the second end 12 are balanced in the z-direction, and this position represents the equilibrium state.

[0021] FIG. 3 is a schematic diagram showing the state in which the inner member 10 of the vibration damping device 100 shown in FIG. 1 has moved in the z direction. FIG. 3( a) shows the state in which the inner member 10 has moved in the z1 direction, and FIG. 3( b) shows the state in which the inner member has moved in the z2 direction. The inner member 10 is configured so that the first end 13 and the second end 12 are attracted to the magnetic poles 21a and 21b of the magnetic device 21. Therefore, regardless of whether the inner member 10 moves in the z1 direction or the z2 direction, the inner member 10 receives a magnetic force in the direction opposite to the direction of movement. That is, when the inner member 10 moves in the z1 direction from the equilibrium state, it receives a magnetic force in the z2 direction, and when the inner member 10 moves in the z2 direction from the equilibrium state, it receives a magnetic force in the z1 direction. In this way, in the vibration damping device 100, a magnetic force is generated in the direction opposite to the direction of movement of the inner member 10. Therefore, for example, if a structure connected to the inner member 10 is displaced, a magnetic force is generated in the direction opposite to the direction of movement, generating a force that attempts to return the inner member 10 to the equilibrium state. Thus, the vibration damping device 100 damps vibrations induced in structures connected to the inner member 10 .

[0022] FIG. 4 shows the relationship between the movement distance of the inner member 10 of the vibration damping device 100 according to the first embodiment and the generated magnetic force. The movement distance indicates the relative distance between the inner member 10 and the outer member 20 in the z direction. A large movement distance means that the magnetic poles 21a and 21b of the magnetic devices 21A and 21B are spaced apart in the z direction from the tip 13a of the first end 13 and the tip 12a of the second end 12. The equilibrium state of the vibration damping device 100 is shown as a movement distance of 0. The loads in FIG. 4 are absolute values. In other words, when the inner member 10 moves in the z1 direction in FIGS. 1 and 3 , the load shown in FIG. 4 acts in the z2 direction according to the movement distance. When the inner member 10 moves in the z2 direction, the load shown in FIG. 4 acts in the z1 direction according to the movement distance.

[0023] Magnetic force is inversely proportional to the square of the distance between the objects it acts on. Thus, as shown in Figure 4, if the inner member 10 is moved in the z direction relative to the outer member 20, the greater the distance moved, the weaker the force attempting to return the inner member 10 to equilibrium.

[0024] FIG. 5 is a schematic diagram of the main configuration of a vibration damping device 100A, which is a modified example of the vibration damping device 100 according to the first embodiment. As shown in FIG. 5, the tip 13a of the first end 13 and the tip 12a of the second end 12 of the inner member 10 of the vibration damping device 100A are configured so that their widths narrow outward in a direction perpendicular to the z-direction. As shown in FIG. 5(a), the tip 13a of the first end 13 and the tip 12a of the second end 12 may be formed with pointed edge portions 13c, 12c, or as shown in FIG. 5(b), the edge portions 13c, 12c may have flat surfaces remaining. In other words, the tip 13a of the first end 13 and the tip 12a of the second end 12 of the inner member 10 may have a trapezoidal shape with inclined portions 13d, 12d whose widths in the z-direction narrow toward the tips. Furthermore, as shown in FIG. 5(c), the tip 13a and the tip 12a may have a stepped structure. In this case, a plurality of end faces 13e located inside the edge portion 13c may be provided. In other words, the tip 13a and the tip 12a may be formed in a stepped shape.

[0025] Fig. 6 is a diagram showing the relationship between the distance traveled by the inner member 10 of the vibration damping device 100A according to the modified example shown in Fig. 5 and the magnetic force generated. In the case of the vibration damping device 100A, the width of the tip 13a of the first end 13 of the inner member 10 is narrow, so the influence of the magnetic force generated by the edge portion 13c of the tip 13a is large, and the influence of the magnetic force generated by the inclined portion 13d is small. Therefore, when the inner member 10 is moved in the z direction from the equilibrium state shown in Fig. 5, the influence of the magnetic force generated by the edge portion 13c becomes dominant.

[0026] Therefore, for example, assuming that edge portion 13c of tip 13a of first end 13 moves slightly in the z1 direction, a force that returns edge portion 13c to a balanced state is generated by a magnetic force generated in the z2 direction. In contrast, the influence of the magnetic force generated in inclined portion 13d is smaller than the influence of the magnetic force generated in edge portion 13c, and the magnetic force that cancels out the magnetic force that returns edge portion 13c to the z2 direction is small. Therefore, the force that returns tip 13a of first end 13 to a balanced state is greater than when tip 13a has a flat surface along the z direction as shown in FIG. 2.

[0027] 2, when tip 13a has a plane along the z direction, moving tip 13a in the z1 direction increases magnetic force fa and decreases magnetic force fb. In this case, the z-direction component of magnetic force fa (i.e., the force directed in the z1 direction) is greater than the z-direction component of magnetic force fb (i.e., the force directed in the z2 direction), and the force pulling tip 13a back in the z2 direction decreases because the z-direction component of magnetic force fa and the z-direction component of magnetic force fb cancel each other out.

[0028] Therefore, in the case of the vibration damping device 100A of the modified example shown in FIG. 5, the reduction in load due to movement of the inner member 10 in the z direction is gradual, as indicated by the solid line in the graph of FIG.

[0029] Furthermore, when the widths of the tip 13a of the first end 13 and the tip 12a of the second end 12 shown in Fig. 5 are configured to be narrower, it is preferable to configure the edge portions 13c and 12c to be closer to the magnetic poles of the magnetic device 21 than the tips 13a and 12a which are flat as shown in Fig. 1. By configuring in this way, the vibration damping device 100A shown in Fig. 5 suppresses a decrease in the magnetic force acting on the inner member 10 relative to the vibration damping device 100, while gradual reduction in the load caused by movement of the inner member 10 in the z direction as shown in Fig. 6.

[0030] FIG. 7 is an example of a schematic diagram of the vibration damping devices 100 and 100A according to the first embodiment, viewed from the z direction. FIG. 7( a) is a diagram illustrating a configuration in which the outer member 20 surrounds the inner member 10 from the x and y directions. As shown in FIG. 7( a), the vibration damping devices 100 and 100A may be configured such that the outer member 20 is formed in a rectangular cylindrical shape and the inner member 10 is disposed inside the outer member 20. The structures shown in FIGS. 1 and 5 illustrate the cross-sectional structure of the A-A portion of FIG. 7( a), which is a cross-sectional structure parallel to the z direction and the x direction. Note that in the vibration damping devices 100 and 100A shown in FIG. 7( a), the cross-sectional structure parallel to the z direction and the y direction is also the same as the structure shown in FIGS. 1 and 5.

[0031] 7(b) is a schematic diagram of another example of the vibration damping devices 100 and 100A when viewed from above (as viewed from the z direction). The outer member 20 does not necessarily have to surround the entire periphery of the inner member 10, and may have a structure in which magnetic devices 21 are disposed on both ends in the x direction.

[0032] Furthermore, the outer member 20 may be circular in plan view or may have another shape, as long as the magnetic poles 21 a and 21 b of the magnetic device 21 are arranged to face the tip 13 a and the second end 13 b of the first end 13 in a direction perpendicular to the z direction.

[0033] 8 is another example of a schematic diagram of the vibration damping devices 100 and 100A according to embodiment 1 as viewed from the z direction. The inner member 10 may include a magnetic body formed in a triangular shape in plan view. The magnetic body is not limited to a triangular shape in plan view, and may have other shapes, such as a rectangular shape.

[0034] 7(a) and 7(b), the magnetic poles 21a of the magnetic devices 21 of the outer member 20 all have the same polarity when viewed in plan, but the orientation of the magnetic devices 21 is not limited to this. As shown in Fig. 8, the four magnetic devices 21 arranged on each of the four sides of the rectangular outer member 20 are arranged so that the north poles are visible on the two opposing left and right sides and the south poles are visible on the two opposing top and bottom sides. The magnetic poles of the magnets of the inner member 10 are arranged to match the magnetic devices 21 of the outer member 20.

[0035] 9 is a schematic diagram of the main configuration of a vibration damping device 100B, which is a modified example of the vibration damping device 100 according to the first embodiment. In the vibration damping device 100B, the tip 13a of the first end 13 and the tip 12a of the second end 12 of the inner member 10 are configured with a pair of magnetic poles. The magnetic device 21 provided in the outer member 20 has its magnetic poles arranged to match the magnetic poles of the tip 13a of the first end 13 and the tip 12a of the second end 12. With this configuration, the widths of the first end 13 and the second end 12 of the inner member 10 in the x direction are reduced, allowing the width of the vibration damping device 100B to be configured compactly.

[0036] Figure 10 is a schematic diagram of the main configuration of a vibration damping device 100C, which is a modified example of the vibration damping device 100 according to the first embodiment. The vibration damping device 100C does not have the first end 13 and the second end 12 located on the x1 side of the inner member 10 shown in Figure 1. By configuring the inner member 10 to limit movement in the x direction and guide movement in the z direction, it is possible to eliminate the first end 13 and the second end 12, which are located symmetrically in the x direction. Even with this structure, a force acts on the inner member 10 to return it to an equilibrium state when it moves in the z direction, so it functions similarly to the vibration damping device 100 shown in Figure 1.

[0037] The vibration damping devices 100, 100A, 100B, and 100C described above can provide a structure that uses the action of magnetic force to return the inner member 10 and the outer member 20 to a state of equilibrium in a structure that includes the inner member 10 and the outer member 20 that are capable of relative reciprocal movement in the z direction. In the vibration damping devices 100, 100A, 100B, and 100C, the outer member 20 is disposed in a position that does not interfere with the direction of movement of the inner member 10. Therefore, whether the inner member 10 moves in the z1 direction or the z2 direction relative to the outer member 20, a load that attempts to return the inner member 10 to a state of equilibrium due to the action of magnetic force acts on the inner member 10, making it possible to damp the vibrating displacement.

[0038] Furthermore, the one-degree-of-freedom magnetic vibration damping device disclosed in Patent Document 1 is configured so that the magnetic force becomes stronger as the displacement in either the vertical direction increases. However, this one-degree-of-freedom magnetic vibration damping device "opposes the polarities of the magnetic poles on the opposing surfaces of the upper and lower annular permanent magnets" and "the central permanent magnet is located between the upper and lower annular permanent magnets and moves axially between the upper and lower annular permanent magnets together with the connecting rod." Therefore, when the central permanent magnet moves in either the vertical or horizontal direction from a balanced state, the magnetic force in the direction of movement increases, and an external force greater than the magnetic force is required to return it to a balanced state. Furthermore, the presence of the upper or lower annular permanent magnet on the extension of the path of the central permanent magnet's movement limits its movement. On the other hand, in the vibration damping devices 100, 100A, 100B, and 100C according to the first embodiment, the outer member 20 is not present on the path of movement of the inner member 10, so the inner member 10 and the outer member 20 do not restrict each other's movement.

[0039] Embodiment 2 A vibration damping device 200 according to embodiment 2 will be described. The vibration damping device 200 according to embodiment 2 is a combination of the vibration damping device 100 according to embodiment 1 and an elastic member 30. Note that components having the same functions and actions as those in embodiment 1 are given the same reference numerals and their description will be omitted.

[0040] 11 is a schematic diagram of the main configuration of a vibration damping device 200 according to embodiment 2. The vibration damping device 200 is a combination of the vibration damping device 100 and an elastic member 30. The elastic member 30 is formed, for example, by a helical spring, and is connected to the inner member 10 so that, when the inner member 10 moves in the z direction, a load is applied in the direction opposite to the movement direction. The elastic member 30 is also fixed to a support body 31, and is configured to be able to expand and contract in accordance with the movement of the inner member 10.

[0041] Figure 12 is a diagram showing the relationship between the movement distance of the inner member 10 and the generated load, and the relationship between the expansion and contraction amount of the elastic member 30 and the generated load in the vibration damping device 100 shown in Figure 1. As shown in Figure 12(a), in the vibration damping device 100 shown in Figure 1, only magnetic force acts on the inner member 10, so as the movement distance increases, the load decreases in inverse proportion to the square of that distance. As shown in Figure 12(b), when the elastic member 30 shown in Figure 11 expands and contracts in the z direction, a load proportional to the expansion and contraction amount is generated in the opposite direction to the expansion and contraction direction.

[0042] Figure 13 is a diagram showing the relationship between the movement distance of the inner member 10 and the generated magnetic force in the vibration damping device 200 according to embodiment 2. In the vibration damping device 200, the magnetic force and the load due to the expansion and contraction of the elastic member 30 act on the inner member 10 in accordance with the displacement of the inner member 10, so the reduction in the load applied to the inner member 10 is suppressed compared to the action of the magnetic force alone shown in Figure 12(a). Therefore, when the inner member 10 is displaced in the z direction, the force that returns the inner member 10 to the equilibrium state decreases while the amount of displacement is small, but as the amount of displacement increases, the force that returns the inner member 10 to the equilibrium state increases due to the action of the elastic member 30.

[0043] In other words, the vibration damping device 200 according to the second embodiment has a smaller change in the force that returns the device to the equilibrium state than the vibration damping device 100 according to the first embodiment.

[0044] Figure 14 is a diagram showing the relationship between the movement distance of the inner member 10 and the generated magnetic force when the vibration damping device 100 in the vibration damping device 200 shown in Figure 11 is replaced with the vibration damping device 100A shown in Figure 5. The two-dot chain line in Figure 14 shows the relationship between the displacement and load of the inner member 10 in the vibration damping device 200 shown in Figure 11, and the solid line in Figure 14 shows the relationship between the displacement and load of the inner member 10 when the inner member 10 shown in Figure 11 is replaced with that of the vibration damping device 100A shown in Figure 5. In the vibration damping device 100A shown in Figure 5, the change in load relative to the displacement of the inner member 10 is gradual, as shown in Figure 6, so when combined with the elastic member 30, the change in the force pulling the inner member 10 back to the equilibrium state is smaller and the change in load becomes closer to flat.

[0045] The elastic member 30 is not limited to a helical spring, but may be a leaf spring, rubber, or any other material that generates elastic force when deformed. In the second embodiment, the elastic member 30 is connected to the lower side of the inner member 10, but the location of the elastic member 30 can be changed as appropriate. For example, the elastic members 30 may be arranged at intervals in the direction of movement of the inner member 10, and a load from the elastic members 30 may act on the inner member 10 when the movement of the inner member 10 exceeds a predetermined amount. Furthermore, if the outer member 20 of the vibration damping device 200 is configured to move, the load from the elastic members 30 may act on the outer member 20.

[0046] 11 may be disposed between the first end 13 and the second end 12 of the inner member 10. For example, the elastic member 30 may be disposed between the first end 13 and the second end 12 of the inner member 10 and fixed to the outer member 20. In this way, when the inner member 10 moves in the z direction relative to the outer member 20, the inner member 10 abuts against the elastic member 30, and the elastic member 30 can function in the same manner as the elastic member 30 of the vibration damping device 200 shown in FIG.

[0047] Embodiment 3. A vibration damping device 300 according to embodiment 3 will be described. The vibration damping device 300 according to embodiment 3 uses electromagnets as the magnetic devices 21A and 21B of the outer member 20 of the vibration damping device 100 according to embodiment 1. Note that components having the same functions and actions as those in embodiments 1 and 2 are given the same reference numerals and their description will be omitted.

[0048] FIG. 15 is a schematic diagram of the main configuration of a vibration damping device 300 according to a third embodiment. In the vibration damping device 300 according to the third embodiment, the magnetic device 21 provided in the outer member 20 of the vibration damping device 100 according to the first embodiment is replaced with an electromagnet. The magnetic device 321 formed by an electromagnet can change the positions of the magnetic poles 21 a and 21 b by partially passing a current through it. In FIG. 15 , the portions of the magnetic device 321 indicated by solid lines are through which current flows, and the portions indicated by dashed lines are through which current does not flow. The magnetic device 321 shown in FIG. 15 is energized so that the magnetic poles are positioned at positions corresponding to the tip 13 a of the first end 13 and the tip 12 a of the second end 12.

[0049] Figure 16 is a schematic diagram of the vibration damping device 300 in the state shown in Figure 15 after the inner member 10 has moved in the z2 direction. In Figure 16, the magnetic device 321 provided in the outer member 20 moves its current-carrying range in the z2 direction in accordance with the movement of the inner member 10. In this way, the magnetic poles 21a and 21b of the magnetic device 321 move in accordance with the movement of the inner member 10, so the vibration damping device 300 can be controlled so that the same magnetic force is applied even when the inner member 10 moves. In the vibration damping device 100 according to embodiment 1, as shown in Figure 4, the magnetic force decreases as the amount of movement increases in the z direction. However, according to the vibration damping device 300 according to embodiment 3, the magnetic force acting on the inner member 10 can be maintained approximately constant even when the inner member 10 moves in the z direction.

[0050] The magnetic device 321 of the vibration damping device 100 is configured, for example, by connecting a plurality of coils 324 in the z direction, and is configured so that the coils 324 to be energized can be selected in accordance with the movement of the inner member 10. For example, the magnetic device 321 is configured so that the central axes of the windings of the plurality of coils 324 are arranged along the z direction, and is configured so that the current flowing through each of the plurality of coils 324 can be controlled. In other words, the magnetic device 321 is configured so that the magnetic poles can move in the z direction by controlling the current flowing through the plurality of coils 324. Note that the magnetic device 321 is not limited to being configured so that the plurality of coils 324 are continuously arranged along the z direction as shown in Figures 15 and 16, and can be modified as appropriate, for example, by arranging the plurality of coils at intervals.

[0051] 15 and 16, the outer member 20 includes the magnetic devices 321A and 321B, but these may be an integrated magnetic device 321.

[0052] Furthermore, the magnetic devices 321A and 321B may control the magnetic force that attracts the first end 13 and the second end 12 by controlling the current flowing through the coil 324. This allows the damping force of the vibration damping device 300 to be controlled.

[0053] The configurations shown in the above embodiments are merely examples, and it is possible to omit or change part of the configurations without departing from the gist of the invention.

[0054] FIG. 17 is a schematic diagram of the main configuration of a vibration damping device 100D, which is a modified example in which the second end 12 is removed from the vibration damping device 100 according to embodiment 1. The vibration damping devices 100, 100A, 100B, 100C, 200, and 300 shown in embodiments 1 to 3 function as vibration damping devices even when either the first end 13 or the second end 12 constituting the end member is omitted. In the modified example shown in FIG. 17, the first end 13 is supported by a structure 14, and the structure 14 is guided by a ball bearing 15, for example. Even in this case, the force shown in FIG. 2(a) acts on the first end 13, and the device functions as a vibration damping device due to magnetic force. Furthermore, in this case, the pair of magnetic poles of the magnetic device 21 do not need to be arranged along the z direction; at least one magnetic pole needs to be arranged facing the first end 13 in a direction perpendicular to the z direction.

[0055] 17 can also be applied to the vibration damping devices 100A, 100B, 100C, 200, and 300. The structures of the structure 14 and the ball bearing 15 can be modified as appropriate, and the ball bearing 15 can be replaced with a sliding bearing or other support structure.

[0056] Furthermore, the present invention described above using the vibration damping devices 100, 100A, 100B, 100C, 100D, 200, and 300 may also include combinations of the features shown in the following Supplementary Notes 1 to 10. Such combinations are described below.

[0057] [Supplementary Note 1] A vibration damping device comprising an inner member and an outer member configured to be capable of relative reciprocating movement along a first direction, wherein the inner member is arranged inside the outer member in a second direction perpendicular to the first direction, and comprises an end member made of a magnetic material and arranged opposite a magnetic pole of the outer member in the second direction, the outer member comprising a magnetic device configured to attract the end member in an equilibrium state, and movement of the end member and the magnetic device in the second direction is restricted so as not to come into contact with each other. [Supplementary Note 2] The vibration damping device according to Supplementary Note 1, wherein the inner member comprises: an end member composed of a first end and a second end arranged apart in a first direction; and a connecting member connecting the first end and the second end in the first direction, wherein the magnetic device has a pair of magnetic poles arranged along the first direction, each of the pair of magnetic poles arranged opposite the first end and the second end in a second direction in a balanced state, and the first end and the second end are configured to be attracted to the magnetic pole of the magnetic device facing in the second direction in the balanced state. [Supplementary Note 3] The vibration damping device according to Supplementary Note 1 or 2, wherein the magnetic device is composed of a plurality of magnetic devices, and the plurality of magnetic devices includes at least one pair of magnetic devices arranged in positions facing each other in the second direction with the inner member in between. [Supplementary Note 4] The vibration damping device according to any one of Supplementary Notes 1 to 3, wherein the end member is made of a permanent magnet, and the magnetic pole of the magnetic device is set to have an opposite polarity to that of the end member. [Supplementary Note 5] The vibration damping device according to any one of Supplementary Notes 1 to 3, wherein the end member is made of a soft magnetic material.[Supplementary Note 6] The vibration damping device according to any one of Supplements 1 to 5, wherein the end member has a structure in which, in a cross section including the central axis of the inner member, the tip in the second direction has a width in the first direction that narrows as it moves outward from the central axis. [Supplementary Note 7] The vibration damping device according to any one of Supplements 1 to 6, further comprising an elastic member that applies a load in a direction opposite to the direction of movement in response to relative movement between the inner member and the outer member in the first direction. [Supplementary Note 8] The vibration damping device according to Supplementary Note 7, wherein the elastic member is connected to at least one of the inner member and the outer member. [Supplementary Note 9] The vibration damping device according to any one of Supplements 1 to 8, wherein the magnetic device is an electromagnet configured so that the pair of magnetic poles are movable in a first direction. [Supplementary Note 10] A vibration damping device according to Supplementary Note 9, wherein the magnetic device includes a plurality of coils arranged with their central axes aligned along a first direction, and wherein magnetic poles move in the first direction by varying some of the plurality of coils to which current is applied.

[0058] DESCRIPTION OF SYMBOLS 10: Inner member 11: Connecting member 12: Second end 12a: Tip 12c: Edge portion 13: First end 13a: Tip 13c: Edge portion 13d: Inclined portion 14: Structure 15: Ball bearing 20: Outer member 21: Magnetic device 21A: Magnetic device 21B: Magnetic device 21a: Magnetic pole 21b: Magnetic pole 30: Elastic member 31: Support 100: Vibration damping device 100A: Vibration damping device 100B: Vibration damping device 100C: Vibration damping device 200: Vibration damping device 300: Vibration damping device 321: Magnetic device 321A: Magnetic device 321B: Magnetic device 324: Coil

Claims

1. A vibration damping device comprising an inner member and an outer member configured to be able to move back and forth relative to each other along a first direction, wherein the inner member is arranged inside the outer member in a second direction perpendicular to the first direction, and comprises an end member made of a magnetic material, the end member consisting of a first end and a second end arranged apart in the first direction, the outer member comprising a magnetic device configured to attract the end member in an equilibrium state, the magnetic device having a pair of magnetic poles arranged along the first direction, each of the pair of magnetic poles arranged opposite the first end and second end in a second direction in an equilibrium state, the first end and second end being configured to attract the magnetic pole of the magnetic device that faces in the second direction in an equilibrium state, and movement of the end member and the magnetic device in the second direction is restricted so as not to come into contact.

2. A vibration damping device according to claim 1, wherein the magnetic device is made up of a plurality of magnetic devices, and the plurality of magnetic devices includes at least one pair of magnetic devices arranged in opposing positions in the second direction with the inner member sandwiched therebetween.

3. A vibration damping device according to claim 1 or 2, wherein the end member is made of a permanent magnet, and the magnetic pole of the magnetic device is set to have the opposite polarity to that of the end member.

4. A vibration damping device according to claim 1 or 2, wherein the end members are made of a soft magnetic material.

5. A vibration damping device according to claim 1 or 2, wherein the end member has a structure in which the width in the first direction of the tip in the second direction narrows as it moves outward from the central axis in a cross section including the central axis of the inner member.

6. A vibration damping device according to claim 1 or 2, further comprising an elastic member that applies a load in a direction opposite to the direction of relative movement between the inner member and the outer member in a first direction.

7. A vibration damping device according to claim 6, wherein the elastic member is connected to at least one of the inner member and the outer member.

8. A vibration damping apparatus according to claim 1, wherein the magnetic device is an electromagnet configured so that the pair of magnetic poles are movable in a first direction.

9. A vibration damping device comprising an inner member and an outer member configured to be capable of reciprocating relative to one another along a first direction, wherein the inner member is arranged inside the outer member in a second direction perpendicular to the first direction, and comprises an end member made of a magnetic material and arranged opposite a magnetic pole of the outer member in the second direction, the outer member comprises a magnetic device configured to attract the end member in an equilibrium state, the end member and the magnetic device are restricted in movement in the second direction so as not to come into contact, and the magnetic device is an electromagnet configured so that a pair of magnetic poles can move in the first direction by varying a current-carrying part.

10. A vibration damping device according to claim 8 or 9, wherein the magnetic device comprises a plurality of coils arranged with their central axes aligned along a first direction, and the magnetic poles move in the first direction by varying some of the plurality of coils to which current is applied.

11. A vibration damping device comprising an inner member and an outer member configured to be capable of relative reciprocating movement along a first direction, wherein the inner member is arranged inside the outer member in a second direction perpendicular to the first direction, and comprises an end member made of a magnetic material arranged opposite a magnetic pole of the outer member in the second direction, the outer member comprises a magnetic device configured to attract the end member in an equilibrium state, the end member and the magnetic device are restricted in movement in the second direction so as not to come into contact, and the end member has a structure in which, in a cross section including the central axis of the inner member, the width in the first direction of the tip in the second direction narrows as it moves outward from the central axis.

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