Eddy current damper device and rotary machine

Abstract

An eddy current damper device (1) comprises: bearings (5) for rotatably supporting a rotating body (2); a cylindrical body (7) that holds the bearings (5); a conductor plate (10) that projects radially outward from the outer circumferential surface of the cylindrical body (2); magnets (14, 15) disposed adjacent to the side surfaces of the conductor plate (10) in the axial direction of the cylindrical body (7); and a yoke (20) surrounding the conductor plate (10) and the magnets (14, 15). An outer end surface (10c) of the conductor plate (10) is in contact with the yoke (20) and held by the yoke (20). The conductor plate (10) includes slits (31, 32, 33, 34) for imparting elasticity to the conductor plate (10). The slits (31, 32, 33, 34) extend over the entirety of the circumference of the conductor plate (10).

Description

Eddy current damper device and rotating machine

[0001] The present invention relates to an eddy current damper device that suppresses vibration of a rotating body, and more particularly to an eddy current damper device that damps vibration of a rotating body by generating eddy currents in a conductor when the rotating body vibrates. The present invention also relates to a rotating machine equipped with such an eddy current damper device.

[0002] An eddy current damper is a vibration control device that damps the vibration of a rotating body by generating eddy currents in a conductor when the rotating body vibrates. Conventional eddy current dampers do not themselves support the rotating body, but are configured to support the rotating body using a support member separate from the eddy current damper. For example, Patent Document 1 discloses a support rod (see reference numeral 6) for supporting a rotating shaft. However, such a support member requires an installation space, and the installation of the eddy current damper increases the number of structural elements. Furthermore, the installation of such a support member may limit the range of application of the eddy current damper.

[0003] Utility Model Publication No. 53-146839 Japanese Patent Application Publication No. 59-217030

[0004] Therefore, the present invention provides a compact eddy current damper device that has a function of supporting a rotating body, and also provides a rotating machine that includes such an eddy current damper device.

[0005] In one aspect, an eddy current damper device for suppressing vibration of a rotating body is provided, comprising: a bearing for rotatably supporting the rotating body; a cylindrical body that holds the bearing; a conductor plate that protrudes radially outward from the outer peripheral surface of the cylindrical body; a magnet that is arranged adjacent to the side of the conductor plate in the axial direction of the cylindrical body; and a yoke that surrounds the conductor plate and the magnet, wherein the outer end surface of the conductor plate is in contact with and held by the yoke, and the conductor plate has a slit that imparts elasticity to the conductor plate, and the slit extends around the entire circumference of the conductor plate.

[0006] In one aspect, the slit includes multiple arc slits extending around the entire circumference of the conductor plate. In another aspect, the multiple arc slits include multiple semicircular slits with different radii of curvature. In another aspect, the slit includes a spiral slit extending around the entire circumference of the conductor plate.

[0007] In one aspect, there is provided a rotary machine including a rotating shaft, an impeller or a turbine fixed to the rotating shaft, an electric motor that rotates the rotating shaft, and the above-described eddy current damper device that rotatably supports the rotating shaft. In one aspect, the rotary machine is a pump device for transporting liquefied gas.

[0008] The conductor plate with the slits is itself elastic in the radial and axial directions and functions to center the rotating body held in the bearing. The conductor plate is held by the yoke and can elastically support the bearing. Therefore, the eddy current damper device can not only damp vibrations of the rotating body rotatably supported by the bearing, but also rotatably support the rotating body. As a result, a compact eddy current damper device can be realized.

[0009] FIG. 10 is a sectional perspective view showing an embodiment of an eddy current damper device. FIG. 11 is a view of a conductor plate viewed from its axial direction. FIG. 12 is a view showing another embodiment of a conductor plate. FIG. 13 is a view explaining the vibration damping principle of an eddy current damper device. FIG. 14 is a view showing another embodiment of an eddy current damper device. FIG. 15 is a view showing yet another embodiment of an eddy current damper device. FIG. 16 is a view showing yet another embodiment of an eddy current damper device. FIG. 17 is a view showing yet another embodiment of an eddy current damper device. FIG. 18 is a view showing yet another embodiment of an eddy current damper device. FIG. 19 is a view showing yet another embodiment of an eddy current damper device. FIG. 19 is a view showing yet another embodiment of an eddy current damper device. FIG. 19 is a view showing yet another embodiment of an eddy current damper device. FIG. 19 is a graph showing experimental results of investigating the damping of radial vibration and axial vibration of a rotating body supported by the eddy current damper device of the embodiment shown in FIG. 7. FIG. 10 is a sectional view showing an embodiment of a rotating machine including an eddy current damper device. FIG. 11 is a sectional view showing yet another embodiment of a rotating machine including an eddy current damper device.

[0010] Embodiments of the present invention will now be described with reference to the drawings. Fig. 1 is a cross-sectional perspective view showing one embodiment of an eddy current damper device. The eddy current damper device 1 is a vibration control device for suppressing vibration of a rotating body 2. As shown in Fig. 1, the eddy current damper device 1 of this embodiment includes a bearing 5 for rotatably supporting the rotating body 2, a cylindrical body 7 that holds the bearing 5, a conductor plate 10 that protrudes radially outward from the outer circumferential surface of the cylindrical body 7, magnets 14 and 15 that are arranged adjacent to the side surface of the conductor plate 10 in the axial direction of the cylindrical body 7, and a yoke 20 that surrounds the conductor plate 10 and the magnets 14 and 15. The conductor plate 10 is in contact with and held by the yoke 20.

[0011] In one example, the rotating body 2 is a rotating shaft of a rotating machine such as a pump device, a blower, a turbo rotating machine, or a turbine power generation device. Examples of the bearings 5 ​​for rotatably supporting the rotating body 2 include rolling bearings such as ball bearings and roller bearings. In the embodiment shown in Fig. 1, two bearings 5 ​​are arranged in parallel. In other embodiments, only one bearing 5 or three or more bearings 5 ​​may be provided.

[0012] The cylindrical body 7 is a bearing holder having a cylindrical shape. The cylindrical body 7 is made of a conductive material, such as aluminum or stainless steel. The bearing 5 is held by the cylindrical body 7. More specifically, the bearing 5 is fitted into the cylindrical body 7, and the outer circumferential surface of the bearing 5 is held by the inner circumferential surface of the cylindrical body 7.

[0013] The conductor plate 10 is made of a conductive material such as aluminum or stainless steel. Aluminum, in particular, has high electrical conductivity in cryogenic environments, and is therefore suitable for use in cryogenic environments when the eddy current damper device 1 is used in such environments. The conductor plate 10 is connected to the outer circumferential surface of the cylindrical body 7. In this embodiment, the conductor plate 10 and the cylindrical body 7 form an integrated structure.

[0014] 1, the yoke 20 has a cylindrical inner peripheral surface 20a, and the conductor plate 10 is a circular conductor disk that contacts the inner peripheral surface 20a of the yoke 20. However, the shape of the conductor plate 10 may be changed as appropriate depending on the shape of the yoke 20. On the other hand, a circular conductor plate 10 is preferable from the viewpoint of having uniform mechanical rigidity in the circumferential direction.

[0015] The two magnets 14, 15 are arranged on either side of the conductor plate 10. In this embodiment, these magnets 14, 15 are annular permanent magnets. Examples of permanent magnets include samarium-cobalt magnets and neodymium magnets. In particular, samarium-cobalt magnets have low temperature dependency and can be used over a wide temperature range, making them suitable for applications in which the eddy current damper device 1 is used in extremely low temperature environments.

[0016] The magnets 14, 15 are fixed to the yoke 20. The two magnets 14, 15 are arranged around the cylindrical body 7 and extend around the entire circumference of the conductor plate 10. The two magnets 14, 15 are not in contact with the cylindrical body 7 or the conductor plate 10. That is, there are gaps between the inner circumferential surfaces of the two magnets 14, 15 and the outer circumferential surface of the cylindrical body 7, and there are gaps between the inner side surfaces 14a, 15a of the two magnets 14, 15 and both side surfaces 10a, 10b of the conductor plate 10.

[0017] One of the two magnets 14, 15 faces one side surface 10a of the conductor plate 10, and the other of the two magnets 14, 15 faces the opposite side surface 10b of the conductor plate 10. The two magnets 14, 15 have inner surfaces 14a, 15a facing the two side surfaces 10a, 10b of the conductor plate 10, respectively, and the inner surfaces 14a, 15a of these two magnets 14, 15 have opposite magnetic poles. In the embodiment shown in FIG. 1 , the inner surface 14a of the magnet 14 has a north pole, and the inner surface 15a of the other magnet 15 has a south pole. In other embodiments, the inner surface 14a of the magnet 14 may have a south pole, and the inner surface 15a of the other magnet 15 may have a north pole. The inner surface 14a and outer surface 14b of the magnet 14 have opposite magnetic poles, and the inner surface 15a and outer surface 15b of the other magnet 15 also have opposite magnetic poles.

[0018] The yoke 20 is made of a magnetic material such as soft electromagnetic iron. The yoke 20 has two wall portions 24, 25 that contact the outer surfaces 14b, 15b of the two magnets 14, 15, respectively. These wall portions 24, 25 have an annular shape that protrudes radially inward toward the outer peripheral surface of the cylinder 7. The conductor plate 10 and the two magnets 14, 15 are disposed between the two wall portions 24, 25. The outer end surface 10c (the outer end surface, outer peripheral surface in the radial direction) of the conductor plate 10 contacts the inner peripheral surface 20a of the yoke 20 and is held by the yoke 20. Therefore, the relative positions of the outer end surface 10c of the conductor plate 10 and the yoke 20 are fixed.

[0019] A bearing 5 is present between the rotating body 2 and the cylindrical body 7. Therefore, the cylindrical body 7, the conductor plate 10, the magnets 14 and 15, and the yoke 20 are non-rotating elements that do not rotate.

[0020] 2 is a view of the conductor plate 10 as viewed from its axial direction. The conductor plate 10 has multiple slits 31, 32, 33, and 34 that impart elasticity to the conductor plate 10. The slits 31, 32, 33, and 34 extend around the entire circumference of the conductor plate 10 as a whole. The slits 31, 32, 33, and 34 are multiple arc slits that extend around the entire circumference of the conductor plate 10. The slits 31, 32, 33, and 34 are arranged at equal intervals around the center of the conductor plate 10.

[0021] Each of the slits 31, 32, 33, and 34 has a semicircular arc shape. More specifically, the slit 31 has an outer arc slit 31A and an inner arc slit 31B that extend in the circumferential direction of the conductor plate 10, and a connecting slit 31C that connects the outer arc slit 31A and the inner arc slit 31B. The radius of curvature of the outer arc slit 31A is larger than the radius of curvature of the inner arc slit 31B. The connecting slit 31C extends obliquely from the end of the outer arc slit 31A to the end of the inner arc slit 31B. The slits 32, 33, and 34 have the same shape and size as the slit 31. The widths of the slits 31, 32, 33, and 34 are the same.

[0022] In other embodiments, the conductor plate 10 may further have a plurality of arc slits radially outward or radially inward of the slits 31, 32, 33, and 34. In still other embodiments, the conductor plate 10 has four arc slits 31, 32, 33, and 34, but in other embodiments, the conductor plate 10 may have two or three arc slits, or five or more arc slits.

[0023] These multiple arc slits 31, 32, 33, and 34 can impart radial and axial elasticity to the metal conductor plate (conductor disk) 10. Therefore, the conductor plate 10 can support the rotating body 2 via the bearing 5 while allowing vibration (translational motion) of the rotating body 2 supported by the bearing 5. The elasticity of the conductor plate 10 depends on the widths of the slits 31, 32, 33, and 34. Therefore, the widths of the slits 31, 32, 33, and 34 are determined so that the conductor plate 10 has the desired elasticity.

[0024] 3 is a diagram showing another embodiment of the conductor plate 10. As shown in FIG. 3, in this embodiment, the conductor plate 10 has a spiral slit 35 that extends around the entire periphery of the conductor plate 10.

[0025] The conductor plate 10 having the multiple arc slits 31, 32, 33, 34 or the spiral slit 35 is itself elastic in the radial and axial directions and has the function of centering the rotating body 2 held in the bearing 5. The conductor plate 10 is held by the yoke 20 and can elastically support the bearing 5. Therefore, the eddy current damper device 1 can not only damp the vibration of the rotating body 2 rotatably supported by the bearing 5, but also rotatably support the rotating body 2. As a result, a compact eddy current damper device 1 can be realized.

[0026] FIG. 4 is a diagram illustrating the vibration damping principle of the eddy current damper device 1. As shown in FIG. 4, a magnetic circuit M1 is generated that extends through the magnets 14 and 15, the conductor plate 10, and the yoke 20. As the rotor 2 vibrates, the bearing 5, the cylindrical body 7, and the conductor plate 10 move translationally as a unit, but the magnets 14 and 15 and the yoke 20 do not. This is because the cylindrical body 7 and the conductor plate 10 are not in contact with the magnets 14 and 15 and the yoke 20. When the conductor plate 10 moves, a change in magnetic flux density occurs near the conductor plate 10 according to Lenz's law, resulting in the generation of an eddy current in the conductor plate 10. This eddy current generates a damping force (resistance force) proportional to the moving speed of the conductor plate 10.

[0027] When the conductor plate 10 moves in the radial direction, the density of the magnetic flux penetrating the conductor plate 10 in the axial direction changes, and eddy currents are generated in response to this change in magnetic flux density. This eddy current generates a damping force (resistance force) that attenuates the radial movement of the conductor plate 10. When the conductor plate 10 moves in the axial direction, the density of the magnetic flux in the conductor plate 10 changes in accordance with the change in the distance between the conductor plate 10 and the magnets 14, 15, and this change in magnetic flux density generates eddy currents. This eddy current generates a damping force (resistance force) that attenuates the axial movement of the conductor plate 10. In this way, the radial and axial movements of the conductor plate 10 are attenuated by the damping forces generated by the eddy currents.

[0028] Figure 5 is a diagram showing another embodiment of the eddy current damper device 1. The configuration and operation of this embodiment not specifically described are the same as those of the embodiment described with reference to Figures 1 to 4, and therefore redundant description will be omitted. In addition to the magnets 14, 15 described above, the eddy current damper device 1 of this embodiment further includes two auxiliary magnets 41, 42 arranged outside the magnets 14, 15 in the axial direction. These auxiliary magnets 41, 42 are fixed to the walls 24, 25 of the yoke 20.

[0029] The auxiliary magnets 41, 42 are annular permanent magnets. The auxiliary magnets 41, 42 are arranged around the cylindrical body 7 and extend along the outer circumferential surface of the cylindrical body 7. The auxiliary magnets 41, 42 are not in contact with the cylindrical body 7 or the conductor plate 10. In other words, there is a gap between the inner circumferential surfaces of the two auxiliary magnets 41, 42 and the outer circumferential surface of the cylindrical body 7, and the magnets 14, 15 are present between the two auxiliary magnets 41, 42 and the conductor plate 10.

[0030] The two auxiliary magnets 41, 42 are arranged on either side of the two magnets 14, 15. The two auxiliary magnets 41, 42 have inner circumferential surfaces 41a, 42a that face the outer circumferential surface of the cylindrical body 7, and the inner circumferential surfaces 41a, 42a of these two auxiliary magnets 41, 42 have opposite magnetic poles. In the embodiment shown in FIG. 5 , the inner circumferential surface 41a of the auxiliary magnet 41 has a south pole, and the inner circumferential surface 42a of the other auxiliary magnet 42 has a north pole. In other embodiments, the inner circumferential surface 41a of the auxiliary magnet 41 may have a north pole, and the inner circumferential surface 42a of the other auxiliary magnet 42 may have a south pole. The inner circumferential surface 41a and the outer circumferential surface 41b of the auxiliary magnet 41 have opposite magnetic poles, and the inner circumferential surface 42a and the outer circumferential surface 42b of the other auxiliary magnet 42 also have opposite magnetic poles.

[0031] As shown in FIG. 5 , a magnetic circuit M1 extends through the magnets 14 and 15, the conductor plate 10, and the yoke 20, while a magnetic circuit M2 extends through the magnets 14 and 15, the auxiliary magnets 41 and 42, the conductor plate 10, the cylinder 7, and the yoke 20. When the conductor plate 10 moves radially, the density of the magnetic flux penetrating the conductor plate 10 in the axial direction changes, and eddy currents are generated in response to this change in magnetic flux density. This eddy current generates a damping force (resistance force) that damps the radial movement of the conductor plate 10. When the conductor plate 10 moves axially, the density of the magnetic flux in the conductor plate 10 and the cylinder 7 changes in accordance with the change in the distance between the conductor plate 10 and the magnets 14 and 15, and this change in magnetic flux density generates eddy currents. This eddy current generates a damping force (resistance force) that damps the axial movement of the conductor plate 10 and the cylinder 7. In this way, the radial and axial movements of the conductor plate 10 are damped by the damping forces generated by the eddy currents.

[0032] In the embodiment described with reference to Figures 1 to 5, one set of conductor plates 10 and a plurality of magnets 14, 15 is provided, but multiple sets of conductor plates 10 and a plurality of magnets 14, 15 may be provided as shown in Figures 6 and 7. Figure 6 is a diagram showing an embodiment of the eddy current damper device 1 including two conductor plates 10 and four magnets 14, 15, and Figure 7 is a diagram showing an embodiment of the eddy current damper device 1 including two conductor plates 10, two magnets 14, 15, and two auxiliary magnets 41, 42. In the embodiment shown in Figures 6 and 7, the arrangement of the magnetic poles of the two sets of magnets 14, 15 is symmetrical with respect to the wall portion 25 of the yoke 20 located between the two sets.

[0033] 6, two conductor plates 10 are arranged in parallel along the axial direction of the cylinder 7, and two magnets 14, 15 are arranged on both sides of each conductor plate 10. The magnets 14, 15 are fixed to wall portions 24, 25, 26 of the yoke 20. In other embodiments, three or more sets of conductor plates 10 and a plurality of magnets 14, 15 may be provided.

[0034] 7, two conductor plates 10 are arranged in parallel along the axial direction of the cylinder 7, two magnets 14, 15 are arranged on either side of each conductor plate 10, and two auxiliary magnets 41, 42 are arranged on either side of the two magnets 14, 15 arranged on either side of each conductor plate 10. The magnets 14, 15 and auxiliary magnets 41, 42 are fixed to the walls 24, 25, 26 of the yoke 20. In other embodiments, three or more sets of conductor plates 10, a plurality of magnets 14, 15, and auxiliary magnets 41, 42 may be provided.

[0035] 8 is a diagram showing yet another embodiment of the eddy current damper device 1. In this embodiment, each of the magnets 14, 15 is a plurality of permanent magnets in a Halbach array configured so that the magnetic flux density is higher on the conductor plate 10 side. The plurality of permanent magnets in the Halbach array are stacked along the radial direction of the conductor plate 10. The number of the plurality of permanent magnets in the Halbach array that constitute each of the magnets 14, 15 is not limited to the embodiment shown in FIG.

[0036] 9 is a diagram showing an embodiment in which the above-described auxiliary magnets 41 and 42 are combined with the multiple permanent magnets in the Halbach array shown in FIG. The auxiliary magnets 41 and 42 are arranged outside the magnets 14 and 15, which are each composed of multiple permanent magnets in the Halbach array. The auxiliary magnet 41 and the innermost permanent magnet of the multiple permanent magnets that make up the magnet 14 form a Halbach array. Similarly, the auxiliary magnet 42 and the innermost permanent magnet of the multiple permanent magnets that make up the magnet 15 also form a Halbach array. According to this embodiment, the magnetic flux density is higher on the cylinder 7 side.

[0037] Fig. 10 is a diagram showing yet another embodiment of the eddy current damper device 1. The embodiment shown in Fig. 10 includes multiple sets of magnets 14, 15 configured from multiple permanent magnets in a Halbach array, and conductor plates 10. Fig. 11 is a diagram showing yet another embodiment of the eddy current damper device 1. The embodiment shown in Fig. 11 includes magnets 14, 15 configured from multiple permanent magnets in a Halbach array, conductor plates 10, and multiple sets of auxiliary magnets 41, 42. In the embodiments shown in Figs. 10 and 11, the arrangement of the magnetic poles of the two sets of magnets 14, 15 is symmetrical with respect to the wall portion 25 of the yoke 20 located between these two sets.

[0038] 12 is a diagram showing yet another embodiment of the eddy current damper device 1. In this embodiment, electromagnets 51 and 52 are used as magnets arranged on both sides of the conductor plate 10. The electromagnets 51 and 52 have side surfaces 51 a and 52 a that face both side surfaces of the conductor plate 10. The electromagnets 51 and 52 are electrically connected to a power cable (not shown), and generate magnetic force when supplied with power.

[0039] 4, a magnetic circuit M1 is generated that extends through the electromagnets 51 and 52, the conductor plate 10, and the yoke 20. When the conductor plate 10 moves, a change in magnetic flux density occurs near the conductor plate 10 according to Lenz's law, resulting in the generation of eddy currents in the conductor plate 10. These eddy currents generate a damping force (resistance force) that is proportional to the moving speed of the conductor plate 10.

[0040] In yet another embodiment, as shown in Fig. 13, the eddy current damper device 1 may include a combination of electromagnets 51, 52 and auxiliary magnets 41, 42. Although not shown, the embodiments described with reference to Figs. 6 and 7 can be applied to the embodiments of Figs. 12 and 13.

[0041] FIG. 14 is a graph showing the results of an experiment investigating the damping of radial and axial vibrations of a rotor 2 supported by the eddy current damper device 1 of the embodiment shown in FIG. 7. The experiment was conducted at room temperature and at cryogenic temperatures (-190°C). The conductor plate 10 was made of aluminum (A1070). As can be seen from the experimental results shown in FIG. 14, the rotor 2 vibrated in the radial and axial directions, and the vibrations gradually damped over time. The experimental results show that the eddy current damper device 1 can damp the vibrations of the rotor 2 while elastically supporting the rotor 2.

[0042] The arc slits 31, 32, 33, and 34 shown in Fig. 2 and the spiral slit 35 shown in Fig. 3 allow fluids such as liquids and air to pass through, thereby cooling the eddy current damper device 1. In particular, a cryogenic liquefied gas, which will be described below, can cool the eddy current damper device 1 and improve the damping performance of the eddy current damper device 1 by increasing the electrical conductivity.

[0043] Fig. 15 is a cross-sectional view showing one embodiment of a rotary machine equipped with the eddy current damper device 1. The rotary machine of the embodiment shown in Fig. 15 is a pump device for transporting liquid. In particular, the pump device shown in Fig. 15 has a structure suitable for transporting liquefied gas. Examples of liquefied gas include liquid hydrogen, liquid helium, liquid methane, liquefied natural gas, liquefied ammonia, liquid nitrogen, liquefied ethylene gas, and liquefied petroleum gas.

[0044] The pump device includes a pump 110, an electric motor 111 that rotates the pump 110, and an eddy current damper device 1A, 1B, or 1C according to any one of the embodiments described with reference to Figures 1 to 13. In one embodiment, the electric motor 111 and the entire pump 110 are immersed in liquefied gas while the pump 110 is operating. Therefore, the electric motor 111 is a wet motor, and the pump 110 is a submersible pump that can operate in liquefied gas.

[0045] The pump 110 has a pump-side rotating shaft 120, multiple impellers 125 fixed to the pump-side rotating shaft 120, and a pump casing 126 that houses the multiple impellers 125. In one embodiment, the pump 110 may be provided with a single impeller 125. The eddy current damper device 1A rotatably supports an end of the pump-side rotating shaft 120. The eddy current damper devices 1B and 1C rotatably support a motor-side rotating shaft 122 of the electric motor 111. The eddy current damper devices 1B and 1C are disposed on both sides of the electric motor 111 in the axial direction. More specifically, the eddy current damper device 1B is disposed between the pump 110 and the electric motor 111, and the eddy current damper device 1C rotatably supports an end of the motor-side rotating shaft 122.

[0046] The electric motor 111 includes a motor-side rotating shaft 122, a motor rotor 131 having a plurality of permanent magnets, and a motor stator 132 for generating a rotating magnetic field. The motor rotor 131 is fixed to the motor-side rotating shaft 122 and rotates integrally with the motor-side rotating shaft 122. Furthermore, the motor-side rotating shaft 122 is connected to the pump-side rotating shaft 120 and rotates integrally with the pump-side rotating shaft 120.

[0047] The electric motor 111 further includes a motor housing 133 to which eddy current damper devices 1B and 1C are fixed, and which rotatably support the motor-side rotating shaft 122. The eddy current damper devices 1B and 1C are disposed on both sides of the motor rotor 131 in the axial direction of the motor-side rotating shaft 122. The motor rotor 131, the motor stator 132, and the eddy current damper devices 1B and 1C are disposed within the motor housing 133.

[0048] When power is supplied to the electric motor 111 through a power cable (not shown), the electric motor 111 rotates the pump-side rotating shaft 120 and the impeller 125 together. As the impeller 125 rotates, liquefied gas is sucked into the pump 110 through the suction port 127 of the pump 110 and discharged through the discharge passage 116.

[0049] The yoke 20 of the eddy current damper device 1A is fixed to a pump casing 126, and the yoke 20 of the eddy current damper devices 1B and 1C is fixed to a motor housing 133. According to the embodiment shown in Fig. 15, the pump side rotating shaft 120 and the motor side rotating shaft 122, which are rotating bodies, are rotatably supported by the eddy current damper devices 1A, 1B, and 1C, and vibrations of the pump side rotating shaft 120 and the motor side rotating shaft 122 are damped by the eddy current damper devices 1A, 1B, and 1C.

[0050] FIG. 16 is a cross-sectional view showing an embodiment of a rotary machine equipped with an eddy current damper device. The configuration of this embodiment, unless otherwise specified, is the same as that of the embodiment described with reference to FIG. 15 , and therefore redundant description will be omitted. In this embodiment, the eddy current damper device 1 rotatably supports the center portion of the pump-side rotating shaft 120. The yoke 20 of the eddy current damper device 1 is fixed to a pump stator 140 that forms a flow path for liquefied gas. In other embodiments, the yoke 20 of the eddy current damper device 1 may be fixed to a pump casing 126. The eddy current damper device 1 is any of the embodiments described with reference to FIGS. 1 to 7. The motor-side rotating shaft 122 of the electric motor 111 is rotatably supported by rolling bearings 141 and 142, and the end of the pump-side rotating shaft 120 is rotatably supported by a plain bearing 143.

[0051] According to the embodiment shown in FIG. 16 , the pump side rotating shaft 120, which is a rotating body, is rotatably supported by the eddy current damper device 1, and the vibration of the pump side rotating shaft 120 is damped by the eddy current damper device 1.

[0052] The temperature at which the viscoelasticity of rubber or the fluidity of oil can be maintained is higher than the temperature of liquefied gas, and therefore a damper device using rubber or oil cannot be used in a pump device that uses liquefied gas. In contrast, the eddy current damper device 1 described with reference to Figures 1 to 13 does not use rubber or oil for vibration damping. Therefore, the eddy current damper device 1 can be used in an extremely low temperature environment. In one example, the temperature at which the eddy current damper device 1 can be used is -100°C or lower, specifically -162°C or lower (below the temperature of liquefied natural gas), and more specifically -253°C or lower (below the boiling point of hydrogen).

[0053] The pump apparatus shown in Figures 15 and 16 is an example of a rotary machine. Other examples of rotary machines include a blower, a turbo rotating machine, and a turbine generator. The configuration of a turbine generator differs from the configuration of the pump apparatus shown in Figures 15 and 16 in that a turbine is used instead of an impeller for pressurizing a liquid. However, the basic configuration of a turbine generator is the same as that of a pump apparatus, so it is not shown in the figures.

[0054] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims.

[0055] The present invention can be used in an eddy current damper device that damps vibrations of a rotating body by generating eddy currents in a conductor when the rotating body vibrates, and can also be used in a rotating machine equipped with such an eddy current damper device.

[0056] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C eddy current damper device 2 rotating body 5 bearing 7 cylindrical body 10 conductive plate 10a, 10b side surface 10c outer end surface 14, 15 magnet 14a, 15a inner surface 14b, 15b outer surface 20 yoke 20a inner circumferential surface 24, 25, 26 wall portion 31, 32, 33, 34 slit 35 spiral slit 41, 42 auxiliary magnet 41a, 42a inner circumferential surface 41b, 42b outer circumferential surface 51, 52 electromagnet 51a, 52a side surface 110 pump 111 electric motor 116 discharge passage 120 pump-side rotating shaft 122 motor-side rotating shaft 125 impeller 126 pump casing 127 suction port 131 Motor rotor 132 Motor stator 133 Motor housing 140 Pump stator

Claims

1. An eddy current damper device for suppressing vibration of a rotating body, comprising: a bearing for rotatably supporting the rotating body; a cylinder for holding the bearing; a conductor plate protruding radially outward from the outer peripheral surface of the cylinder; a magnet arranged adjacent to the side of the conductor plate in the axial direction of the cylinder; and a yoke surrounding the conductor plate and the magnet, wherein the outer end surface of the conductor plate is in contact with and held by the yoke, and the conductor plate has a slit that imparts elasticity to the conductor plate, and the slit extends around the entire circumference of the conductor plate.

2. An eddy current damper device according to claim 1, wherein said slits include multiple arcuate slits extending around the entire periphery of said conductor plate.

3. An eddy current damper device according to claim 2, wherein the multiple arc slits include a plurality of semi-circular slits with different radii of curvature.

4. The eddy current damper device according to claim 1, wherein the slit includes a spiral slit extending around the entire periphery of the conductor plate.

5. A rotary machine comprising: a rotating shaft; an impeller or turbine fixed to said rotating shaft; an electric motor that rotates said rotating shaft; and an eddy current damper device according to any one of claims 1 to 4 that rotatably supports said rotating shaft.

6. The rotary machine according to claim 5, wherein the rotary machine is a pumping device for transporting liquefied gas.

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