Axle box support device

Abstract

To provide an axle box support device that can ensure sufficient damping force. [Solution] The axle box support device (40, 40A) comprises a first cylindrical body (41), a second cylindrical body (42), a group of permanent magnets (43, 43A), a conductor (44), and a coil spring (45). The group of permanent magnets (43) is held on the circumferential surface of the first cylindrical body (41) and is arranged in a Halbach arrangement along the axial direction of the first cylindrical body (41). The group of permanent magnets (43, 43A) consists of a plurality of first magnets (431) having a magnetization direction in the radial direction of the first cylindrical body (41) and a plurality of second magnets (432) having a magnetization direction in the axial direction of the first cylindrical body (41). At least one of the plurality of first magnets (431) is a large-thickness magnet (431a) having a thickness greater than the thickness of each of the plurality of second magnets (432). The sum of the individual thicknesses of the multiple first magnets (431) is greater than or equal to the sum of the individual thicknesses of the multiple second magnets (432).

Description

Technical Field

[0001] The present disclosure relates to a journal box support device.

Background Art

[0002] In a railway vehicle, a journal box support device is used to hold a journal box with respect to a bogie frame. The journal box support device mainly includes a journal spring. The journal spring is disposed on the journal box and elastically supports the bogie frame. Generally, a coil spring is applied to the journal spring. The journal box support device usually includes a vibration damping mechanism. When the railway vehicle is running, the vibration transmitted from the journal box to the bogie frame is damped by the vibration damping mechanism. For example, an oil damper, a high damping rubber, or the like is used as the vibration damping mechanism.

[0003] Particularly, in order to damp the vibration in the vertical direction, Japanese Patent Application Laid-Open No. 11-94008 (Patent Document 1) and Japanese Utility Model Laid-Open No. 6-23864 (Patent Document 2) describe a journal box support device including a coil spring and a vibration damping mechanism. The journal box support device of Patent Document 1 includes a liquid-filled mount as the vibration damping mechanism. In the liquid-filled mount, a damping plate connected to the bogie frame is immersed in a highly viscous liquid (oil) in a case attached to the journal box. When the bogie frame vibrates in the vertical direction with respect to the journal box, the damping plate stirs the highly viscous liquid, thereby damping the vertical vibration of the bogie frame with respect to the journal box.

[0004] The journal box support device of Patent Document 2 includes a cylindrical roll rubber as the vibration damping mechanism. The roll rubber is fitted in a space between a roll rubber receiving outer cylinder connected to the bogie frame and a roll rubber receiving inner cylinder connected to the journal box so as to be freely rotatable. When the bogie frame vibrates in the vertical direction with respect to the journal box, the roll rubber elastically deform, thereby damping the vertical vibration of the bogie frame with respect to the journal box.

[0005] These axle box support devices utilize either liquid-filled mounts or roll rubber as vibration damping mechanisms. In the case of liquid-filled mounts, there is a risk of oil leakage, and the oil deteriorates over time. In the case of roll rubber, the rubber deteriorates over time. The deterioration of oil and rubber over time can degrade the damping performance of the vibration damping mechanism. Therefore, in both the axle box support devices described in Patent Documents 1 and 2, regular maintenance of the vibration damping mechanism is essential. To reduce costs, it is desirable to minimize the number of replacement parts and reduce the need for regular maintenance.

[0006] In contrast to such axle box support devices, Japanese Patent Publication No. 2023-177124 (Patent Document 3) proposes an axle box support device equipped with a vertical damping mechanism that exerts vertical damping force due to eddy current resistance as a vibration damping mechanism. Specifically, the vertical damping mechanism includes an outer cylinder positioned at the top of the axle box and an inner cylinder extending from the bogie frame side toward the axle box and located inside the outer cylinder. A conductor is arranged on the inner circumferential surface of the outer cylinder, and ring-shaped permanent magnets are arranged in multiple stages on the outer circumferential surface of the inner cylinder so as to face the conductor.

[0007] In the axle box support device of Patent Document 3, when relative vertical displacement occurs between the axle box and the bogie frame, eddy currents are generated in the conductors arranged in the outer cylinder. The interaction between the eddy currents generated in the conductors and the magnetic field formed by the permanent magnets generates a resistive force (Lorentz force) in the opposite direction to the direction of relative displacement of the inner cylinder relative to the outer cylinder, thereby preventing the relative displacement of the inner cylinder relative to the outer cylinder. As a result, vertical vibration of the bogie frame relative to the axle box is dampened. The permanent magnets and conductors constituting the vibration damping mechanism are separate and independent and do not come into contact with each other, so deterioration over time is unlikely. Therefore, periodic maintenance can be reduced in the axle box support device of Patent Document 3. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 11-94008 [Patent Document 2] Japanese Utility Model Publication No. 6-23864 [Patent Document 3] Japanese Patent Publication No. 2023-177124 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] During the operation of railway vehicles, vibrations in the low-frequency range of a few Hz or less affect ride comfort. However, in vibration damping mechanisms that utilize eddy currents, such as those described in Patent Document 3, the driving force that induces eddy currents is small for low-frequency vibrations, making it difficult to obtain sufficient damping force. As a countermeasure, increasing the amount of permanent magnets can be considered, but the space available for installing permanent magnets is limited. Therefore, it becomes difficult to secure sufficient damping force with the axle box support device described in Patent Document 3.

[0010] The purpose of this disclosure is to provide an axle box support device that can ensure sufficient damping force. [Means for solving the problem]

[0011] The axle box support device according to this disclosure holds the axle box with respect to the bogie frame. The axle box support device comprises a first cylindrical body, a second cylindrical body, a group of permanent magnets, a conductor, and a coil spring. The first cylindrical body is made of a magnetic material and has a central axis extending in the vertical direction. The first cylindrical body is positioned between the side beam of the bogie frame and the axle box and is fixed to one of the side beam and the axle box. The second cylindrical body is made of a magnetic material and has a central axis extending in the vertical direction. The second cylindrical body is positioned coaxially with the first cylindrical body either inside or outside the first cylindrical body and is fixed to the other of the side beam and the axle box.

[0012] The permanent magnet group is held on the inner and outer circumferential surfaces of the first cylinder, specifically on the circumferential surface on the second cylinder side, and is arranged in a Halbach arrangement along the axial direction of the first cylinder. The permanent magnet group consists of a plurality of first magnets having a magnetization direction in the radial direction of the first cylinder, and a plurality of second magnets having a magnetization direction in the axial direction of the first cylinder. The conductor is provided on the inner and outer circumferential surfaces of the second cylinder, specifically on the circumferential surface on the first cylinder side, facing the permanent magnet group. The coil spring is positioned on the axle box, coaxial with the first and second cylinders, either inside or outside the first and second cylinders, and supports the side beams of the bogie frame.

[0013] If we define the axial dimension of each of the multiple first magnets and the multiple second magnets as thickness, then at least one of the multiple first magnets is a large-thickness magnet, having a thickness greater than the thickness of each of the multiple second magnets. The sum of the individual thicknesses of the multiple first magnets is greater than or equal to the sum of the individual thicknesses of the multiple second magnets. [Effects of the Invention]

[0014] According to the shaft box support device of this disclosure, sufficient damping force can be ensured. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a top view of a bogie equipped with the axle box support device according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view showing a schematic configuration of the axle box support device according to the first embodiment. [Figure 3] Figure 3 is an enlarged cross-sectional view of the area near the group of permanent magnets shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view showing a modified example of the axle box support device according to the first embodiment. [Figure 5] Figure 5 is an enlarged cross-sectional view of the area near the permanent magnet group in the axle box support device according to the second embodiment. [Figure 6] Figure 6 is an enlarged cross-sectional view of the area near the permanent magnet group in the axle box support device of Comparative Example 1-1. [Figure 7]FIG. 7 is an enlarged cross-sectional view near the permanent magnet group in the axle box support device of Comparative Example 1-2. [Figure 8] FIG. 8 is an enlarged cross-sectional view near the permanent magnet group in the axle box support device of Comparative Example 1-3. [Figure 9] FIG. 9 is an enlarged cross-sectional view near the permanent magnet group in the axle box support device of Comparative Example 2. [Figure 10] FIG. 10 is an enlarged cross-sectional view near the permanent magnet group in the axle box support device of Invention Example 1-1. [Figure 11] FIG. 11 is an enlarged cross-sectional view near the permanent magnet group in the axle box support device of Invention Example 1-2. [Figure 12] FIG. 12 is an enlarged cross-sectional view near the permanent magnet group in the axle box support device of Invention Example 2-2. [Figure 13] FIG. 13 is a diagram showing the vibration attenuation coefficient when the vibration frequency is 1 Hz. [Figure 14] FIG. 14 is a diagram showing the vibration attenuation coefficient when the vibration frequency is 5 Hz. [Figure 15] FIG. 15 is a diagram showing the magnetic flux density distribution around the permanent magnet group corresponding to the configuration of the permanent magnet group shown in FIG. 10. [Figure 16] FIG. 16 is a diagram showing the magnetic flux density distribution around the permanent magnet group corresponding to the configuration of the permanent magnet group shown in FIG. 11. [Figure 17] FIG. 17 is a diagram showing the magnetic flux density distribution around the permanent magnet group corresponding to the configuration of the permanent magnet group shown in FIG. 5. [Figure 18] FIG. 18 is a diagram showing the magnetic flux density distribution around the permanent magnet group corresponding to the configuration of the permanent magnet group shown in FIG. 12.

Embodiments for Carrying Out the Invention

[0016] The axle box support device according to this embodiment holds the axle box relative to the bogie frame. The axle box support device comprises a first cylindrical body, a second cylindrical body, a group of permanent magnets, a conductor, and a coil spring. The first cylindrical body is made of a magnetic material and has a central axis extending in the vertical direction. The first cylindrical body is positioned between the side beam of the bogie frame and the axle box and is fixed to one of the side beam and the axle box. The second cylindrical body is made of a magnetic material and has a central axis extending in the vertical direction. The second cylindrical body is positioned coaxially with the first cylindrical body either inside or outside of the first cylindrical body and is fixed to the other of the side beam and the axle box.

[0017] The permanent magnet group is held on the inner and outer circumferential surfaces of the first cylinder, specifically on the circumferential surface on the second cylinder side, and is arranged in a Halbach arrangement along the axial direction of the first cylinder. The permanent magnet group consists of a plurality of first magnets having a magnetization direction in the radial direction of the first cylinder, and a plurality of second magnets having a magnetization direction in the axial direction of the first cylinder. The conductor is provided on the inner and outer circumferential surfaces of the second cylinder, specifically on the circumferential surface on the first cylinder side, facing the permanent magnet group. The coil spring is positioned on the axle box, coaxial with the first and second cylinders, either inside or outside the first and second cylinders, and supports the side beams of the bogie frame.

[0018] If we define the axial dimension of each of the multiple first magnets and the multiple second magnets as thickness, then at least one of the multiple first magnets is a large-thickness magnet, having a thickness greater than the thickness of each of the multiple second magnets. The sum of the individual thicknesses of the multiple first magnets is greater than or equal to the sum of the individual thicknesses of the multiple second magnets (first configuration).

[0019] In conventional axle box support configurations, even if a Halbach arrangement is applied to the permanent magnet group, if the thickness of the first magnet is less than or equal to that of the second magnet, it may not be possible to sufficiently increase the magnetic flux density introduced into the conductor. This is because the magnetic resistance of the air gap between the first magnet and the conductor causes the magnetic flux radiating radially from the first magnet and the magnetic flux entering the first magnet to diffuse axially.

[0020] In contrast, in the first configuration, the group of permanent magnets, consisting of a first magnet and a second magnet, is arranged in a Halbach arrangement on the circumferential surface of the first cylindrical body. Furthermore, in the group of permanent magnets, the sum of the thicknesses of the first magnets is greater than or equal to the sum of the thicknesses of the second magnets, and thicker magnets are partially provided. This reduces the influence of the air gap between the first magnet and the conductor on the magnetic flux radiating radially from the first magnet and the magnetic flux entering the first magnet, thereby suppressing the diffusion of magnetic flux in the axial direction. Therefore, according to the first configuration, the magnetic flux density introduced into the conductor can be significantly increased, and sufficient damping force can be ensured.

[0021] In the axle box support device according to the first configuration, the plurality of first magnets may consist of one or more inward-facing magnets whose magnetization direction is inward in the radial direction of the first cylindrical body, and one or more outward-facing magnets whose magnetization direction is outward in the radial direction. In this case, it is preferable that the sum of the thicknesses of each of the one or more inward-facing magnets is equal to the sum of the thicknesses of each of the one or more outward-facing magnets (second configuration). In this configuration, with respect to the magnetic flux from the group of permanent magnets to the conductor, the diffusion of magnetic flux in the axial direction is suppressed. That is, magnetic leakage can be suppressed.

[0022] In the axle box support device according to the first or second configuration, it is preferable that the sum of the thicknesses of each of the multiple first magnets is at least twice the sum of the thicknesses of each of the multiple second magnets (third configuration). In this case, it is easier to ensure sufficient damping force in the axle box support device.

[0023] In the axle box support device according to any of the first to third configurations, the plurality of first magnets may consist of small-thickness magnets having a thickness smaller than the thickness of the large-thickness magnet and the large-thickness magnet. In this case, it is preferable that the large-thickness magnet is constructed by stacking a plurality of small-thickness magnets in the axial direction (fourth configuration).

[0024] In the fourth configuration, since the large-thick magnet is constructed by stacking multiple small-thick magnets, it is sufficient to prepare multiple small-thick magnets as multiple first magnets. Therefore, there is no need to prepare magnets of multiple thicknesses as multiple first magnets, which can reduce the manufacturing cost of the axle box support device.

[0025] In the axle box support device according to the fourth configuration, each of the multiple second magnets may have the same shape as the small-thickness magnet (fifth configuration). In the fifth configuration, the first magnet and the second magnet may be manufactured, for example, by preparing magnetic materials of the same shape and selecting the magnetization direction as necessary. In this case, it is not necessary to prepare magnets of multiple shapes for the first and second magnets, and the manufacturing cost of the axle box support device can be further reduced.

[0026] In the axle box support device according to any of the first to fifth configurations, the first cylinder is fixed to the axle box, and the second cylinder may be positioned outside the first cylinder and fixed to the side beam. In this case, the group of permanent magnets may be held on the outer circumferential surface of the first cylinder, and the conductor may be provided on the inner circumferential surface of the second cylinder. The coil spring may be positioned outside the first and second cylinders (sixth configuration).

[0027] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or equivalent components are denoted by the same reference numerals, and the same description will not be repeated.

[0028] <First Embodiment> The axle box support device according to this embodiment is used in railway vehicles. A railway vehicle comprises a bogie and a car body. The bogies are usually positioned at the front and rear of the car body, respectively. The car body is supported by a pair of left and right air springs positioned on each bogie. Generally, multiple vehicles are coupled together and run on rails. In such a railway vehicle, the axle box support device is provided on the bogie. Below, we will first describe a bogie including the axle box support device according to this embodiment.

[0029] [Bogie configuration] Figure 1 is a top view of a bogie 100 equipped with an axle box support device according to the first embodiment. The bogie 100 comprises a bogie frame 10, two wheelsets 20F, 20R, four axle boxes 30, and four axle box support devices 40. The bogie 100 is a bolsterless bogie. In this specification, the direction of travel of the bogie 100, that is, the direction along the rails, may be referred to as the front-rear direction or longitudinal direction. The direction perpendicular to the direction of travel of the bogie 100, that is, the direction perpendicular to the rails, may be referred to as the left-right direction. The direction perpendicular to the front-rear direction and the left-right direction may be referred to as the up-down direction or vertical direction.

[0030] The bogie frame 10 is the main structural frame that constitutes the bogie 100. The bogie frame 10 includes a pair of side beams 11 and at least one cross beam 12. The side beams 11 extend in the front-rear direction and are arranged side by side in the left-right direction of the bogie 100. The side beams 11 are connected by the cross beam 12. In this embodiment, the side beams 11 are provided with spring caps 111 at their longitudinal ends. However, the arrangement of the spring caps 111 is not limited to the longitudinal ends of the side beams 11. For example, the spring caps 111 may be located in the longitudinal center of the side beams 11. The spring caps 111 include a base portion 111a that constitutes the upper part and a circular through hole 111b provided in the center of the base portion 111a.

[0031] The wheelsets 20F and 20R are positioned on the front and rear sides of the bogie 100, respectively. The wheelsets 20F and 20R are supported by the bogie frame 10. Each of the wheelsets 20F and 20R includes a pair of wheels 21 and an axle 22. The axle 22 extends in the left-right direction of the bogie 100. The wheels 21 are positioned on both the left and right sides of the axle 22 and are fixed to the axle 22. On the axle 22, an axle box 30 is provided on the outside of the wheels 21. The axle 22, i.e., the wheelsets 20F and 20R, are rotatably supported around the axle by the axle box 30.

[0032] The spring cap 111 of the side beam 11 is positioned above the axle box 30. An axle box support device 40 is positioned above the axle box 30. The axle box support device 40 holds the axle box 30 relative to the bogie frame 10 (side beam 11).

[0033] [Configuration of the axle box support device] The axle box support device 40 in this embodiment is a monolink type axle box support device. In the case of a monolink type axle box support device, the axle box 30 and the spring cap 111 of the side beam 11 are elastically connected in the vertical direction by a coil spring (axle spring), and the axle box 30 and the side beam 11 are further elastically connected in the front-rear direction by a link. However, the axle box support device 40 in this embodiment may be an axle box support device other than a monolink type.

[0034] The configuration of the axle box support device 40 will be described in detail with reference to Figure 2. Figure 2 is a cross-sectional view showing the schematic configuration of the axle box support device 40 according to the first embodiment. Figure 2 shows the II-II cross-section of Figure 1. As shown in Figure 2, the axle box support device 40 comprises a first cylindrical body 41, a second cylindrical body 42, a group of permanent magnets 43, a conductor 44, and a coil spring 45. The axle box support device 40 of this embodiment further comprises a support column 46, a spring seat 47, a link 48, and a rubber bush 49.

[0035] First, the coil spring 45 is positioned on the axle box 30 and supports the side beam 11 of the bogie frame 10. For this reason, the coil spring 45 is positioned between the side beam 11 and the axle box 30. The coil spring 45 has an elastic support function in the vertical direction. Inside or outside the coil spring 45, a mechanism is provided to dampen the vertical vibration of the bogie frame 10 relative to the axle box 30. This mechanism includes a first cylindrical body 41, a second cylindrical body 42, a group of permanent magnets 43, and a conductor 44.

[0036] The first cylindrical body 41 has a cylindrical shape and extends in the vertical direction. The first cylindrical body 41 has a central axis X that extends in the vertical direction. In this specification, the direction in which the central axis X of the first cylindrical body 41 extends may be referred to as the axial direction, and the direction perpendicular to the axial direction may be referred to as the radial direction.

[0037] The first cylindrical body 41 is positioned between the side beam 11 of the bogie frame 10 and the axle box 30. In this embodiment, the first cylindrical body 41 is positioned inside the coil spring 45 and coaxially with the coil spring 45. That is, the central axis X of the first cylindrical body 41 substantially coincides with the central axis of the coil spring 45. The first cylindrical body 41 has a lower end portion 411 located on the axle box 30 side. The first cylindrical body 41 also has an inner circumferential surface 412 on the radially inward side and an outer circumferential surface 413 on the radially outward side.

[0038] The first cylindrical body 41 is fixed to either the side beam 11 or the axle box 30. In this embodiment, the first cylindrical body 41 is fixed to the axle box 30. Specifically, the first cylindrical body 41 is indirectly fixed to the axle box 30 via a support column 46. The support column 46 is fixed to the axle box 30.

[0039] The first cylindrical body 41 is made of a magnetic material. This magnetic material is a ferromagnetic material such as carbon steel or cast steel.

[0040] The second cylinder 42 has a cylindrical shape similar to the first cylinder 41 and extends in the vertical direction. The second cylinder 42 has a central axis that extends in the vertical direction. The second cylinder 42 is positioned coaxially with the first cylinder 41 either inside or outside the first cylinder 41. In this embodiment, the second cylinder 42 is positioned outside the first cylinder 41. That is, in this example, the second cylinder 42 is positioned coaxially with the first cylinder 41 and the coil spring 45 inside the coil spring 45. In this case, the central axis of the second cylinder 42 substantially coincides with the central axis X of the first cylinder 41 and the central axis of the coil spring 45.

[0041] The second cylindrical body 42 has an upper end portion 421 located on the side beam 11 side. The second cylindrical body 42 also has an inner circumferential surface 422 on the radially inward side and an outer circumferential surface 423 on the radially outward side. In this embodiment, the second cylindrical body 42 further includes a flange portion 424 that protrudes radially outward from near the upper end portion 421 of the second cylindrical body 42.

[0042] The second cylindrical body 42 is fixed to the other side beam 11 and axle box 30. That is, the second cylindrical body 42 is fixed to the side beam 11 and axle box 30 that the first cylindrical body 41 is not fixed to. In this embodiment, since the first cylindrical body 41 is fixed to the axle box 30, the second cylindrical body 42 is fixed to the side beam 11. Specifically, the upper end portion 421 of the second cylindrical body 42 fits into the through hole 111b of the spring cap 111 of the side beam 11, and the flange portion 424 contacts the lower surface of the base portion 111a of the spring cap 111, and in this state the second cylindrical body 42 is fixed to the side beam 11.

[0043] The second cylindrical body 42 is made of a magnetic material. This magnetic material is a ferromagnetic material such as carbon steel or cast steel.

[0044] The permanent magnet group 43 is an assembly of multiple first magnets 431 and multiple second magnets 432, as will be described in detail later. The permanent magnet group 43 has a cylindrical shape as a whole. The permanent magnet group 43 is held on the inner circumferential surface 412 and the outer circumferential surface 413 of the first cylindrical body 41, specifically on the side facing the second cylindrical body 42. In this embodiment, the permanent magnet group 43 is held on the outer circumferential surface 413 of the first cylindrical body 41. In this case, the permanent magnet group 43 is substantially coaxial with the second cylindrical body 42.

[0045] Referring to Figure 3, the specific configuration of the permanent magnet group 43 will be described below. Figure 3 is an enlarged cross-sectional view of the vicinity of the permanent magnet group 43 shown in Figure 2. As shown in Figure 3, the permanent magnet group 43 consists of a plurality of first magnets 431 and a plurality of second magnets 432. Each first magnet 431 has a magnetization direction in the radial direction of the first cylindrical body 41. Each second magnet 432 has a magnetization direction in the axial direction of the first cylindrical body 41. In other words, each of the plurality of first magnets 431 has magnetic poles (N pole and S pole) aligned in the radial direction of the first cylindrical body 41. Each of the plurality of second magnets 432 has magnetic poles aligned in the axial direction of the first cylindrical body 41. In Figure 3, the magnetization direction is represented by an arrow, with the starting point of the arrow representing the S pole and the ending point representing the N pole.

[0046] The magnetization direction of the first magnet 431 does not have to perfectly coincide with the radial direction of the first cylindrical body 41. Also, the magnetization direction of the second magnet 432 does not have to perfectly coincide with the axial direction of the first cylindrical body 41.

[0047] Each of the plurality of first magnets 431 and the plurality of second magnets 432 typically has an annular shape. The outer diameters of the first magnets 431 are the same as those of the second magnets 432. Preferably, the outer diameter of the first magnets 431 is the same as that of the second magnets 432. However, the outer diameter of the first magnets 431 may be different from that of the second magnets 432.

[0048] In this specification, the axial dimension of each of the plurality of first magnets 431 and the plurality of second magnets 432 is defined as thickness. At least one of the plurality of first magnets 431 is a thick magnet 431a. The thick magnet 431a has a thickness greater than the thickness of each of the plurality of second magnets 432. For this reason, the plurality of first magnets 431 are classified into thick magnets 431a and magnets with a thickness less than the thick magnets 431a. However, the plurality of first magnets 431 may consist only of thick magnets 431a. It is preferable that the thick magnets 431a are not placed at the upper or lower end of the permanent magnet group 43.

[0049] From another perspective, the multiple first magnets 431 consist of one or more inward-facing magnets 431i and one or more outward-facing magnets 431o. The magnetization direction of the inward-facing magnets 431i is radially inward. The magnetization direction of the outward-facing magnets 431o is radially outward. For this reason, the multiple first magnets 431 are classified into inward-facing magnets 431i and outward-facing magnets 431o.

[0050] The permanent magnet group 43 is arranged in a Halbach arrangement along the axial direction of the first cylindrical body 41. In the Halbach arrangement, the first magnets 431 and the second magnets 432 are arranged alternately in the axial direction. In this embodiment, as described above, the permanent magnet group 43 is held on the outer circumferential surface 413 of the first cylindrical body 41. In this case, in order to increase the degree of magnetic flux focusing radially outward from the permanent magnet group 43, the magnetization direction of the second magnet 432 adjacent to the outward-facing magnet 431o is toward the outward-facing magnet 431o. On the other hand, the magnetization direction of the second magnet 432 adjacent to the inward-facing magnet 431i is toward the inward-facing magnet 431i.

[0051] In the Halbach array of this embodiment, the magnetic flux of the second magnet 432 adjacent to the outward-facing magnet 431o enters and merges with the outward-facing magnet 431o, thereby increasing the degree of focusing of the magnetic flux emanating from the outward-facing magnet 431o. By a similar principle, the degree of focusing of the magnetic flux entering the inward-facing magnet 431i is also increased. As a result, the permanent magnet group 43 forms a magnetic circuit in which the degree of focusing of the radially outward magnetic flux is increased.

[0052] In the permanent magnet group 43 shown in Figure 3, the magnetization directions of the magnets are, in order from the top end to the bottom end, radially outward, axially upward, radially inward, axially downward, and radially outward. That is, the magnetization directions rotate by 90° each time. However, in the permanent magnet group 43, the magnetization directions of the magnets may be, in order from the top end to the bottom end, radially inward, axially downward, radially outward, axially upward, and radially inward.

[0053] The sum of the individual thicknesses of the multiple first magnets 431 is greater than or equal to the sum of the individual thicknesses of the multiple second magnets 432. In this embodiment, the permanent magnet group 43 consists of three first magnets 431 and two second magnets 432. One of the three first magnets 431 is a large-thick magnet 431a. This large-thick magnet 431a is an inward-facing magnet 431i. The other two of the three first magnets 431 are outward-facing magnets 431o, which have a thickness smaller than that of the large-thick magnet 431a. The thickness of each of these two outward-facing magnets 431o is the same as the thickness of each of the two second magnets 432. Therefore, in this embodiment, the sum of the individual thicknesses of the multiple first magnets 431 is greater than the sum of the individual thicknesses of the multiple second magnets 432 by the thickness of the large-thick magnet 431a.

[0054] In this embodiment, each of the first and second magnets 431 and 432 is composed of a single magnet. However, each of the first and second magnets 431 and 432 may be divided in the circumferential direction. That is, each of the first and second magnets 431 and 432 may be composed of small, arc-shaped magnets arranged in the circumferential direction. Magnetization of each of the first and second magnets 431 and 432 may be performed before or after attachment to the first cylindrical body 41.

[0055] Returning to Figure 2, the conductor 44 is provided on the inner circumferential surface 422 and the outer circumferential surface 423 of the second cylindrical body 42, on the side facing the first cylindrical body 41, opposite the group of permanent magnets 43. For this reason, the conductor 44 has a cylindrical shape. The conductor 44 is substantially coaxial with the first cylindrical body 41. That is, the central axis of the conductor 44 substantially coincides with the central axis X of the first cylindrical body 41. In this embodiment, the conductor 44 is provided on the inner circumferential surface 422 of the second cylindrical body 42. The conductor 44 may be provided over the entire axial area of ​​the inner circumferential surface 422 of the second cylindrical body 42, or it may be provided over a part of the axial area of ​​the inner circumferential surface 422 of the second cylindrical body 42.

[0056] The conductor 44 is made of a highly conductive material. For example, the conductor 44 is made of copper, copper alloy, aluminum, aluminum alloy, etc. The conductor 44 can be formed by, for example, plating, build-up welding, welding of copper plates, or using a copper-steel cladding material.

[0057] The coil spring 45 is a spring formed from a linear or rod-shaped material into a helical shape. The coil spring 45 is arranged on the shaft box 30 coaxially with the first cylindrical body 41 and the second cylindrical body 42. Therefore, the central axis of the coil spring 45 substantially coincides with the central axis X of the first cylindrical body 41. The coil spring 45 includes an upper end 451 on the upper side in the vertical direction and a lower end 452 on the lower side in the vertical direction.

[0058] The coil spring 45 is positioned on the shaft box 30 either inside or outside the first cylindrical body 41 and the second cylindrical body 42. In this embodiment, the coil spring 45 is provided on the shaft box 30 outside the first cylindrical body 41 and the second cylindrical body 42. The first cylindrical body 41, the permanent magnet group 43, the conductor 44, the second cylindrical body 42, and the coil spring 45 are arranged concentrically in order radially outward from the central axis X.

[0059] The coil spring 45 is interposed between the flange 424 of the second cylindrical body 42 and the spring seat 47 provided on the axle box 30. The upper end 451 of the coil spring 45 is in contact with the flange 424 of the second cylindrical body 42, and the lower end 452 of the coil spring 45 is in contact with the spring seat 47.

[0060] In this case, the flange 424 of the second cylindrical body 42 is subjected to the elastic repulsive force of the coil spring 45. As a result, the coil spring 45 presses the flange 424 of the second cylindrical body 42 toward the base portion 111a of the spring cap 111. Due to this elastic repulsive force of the coil spring 45, the second cylindrical body 42 is pressed against the side beam 11 and fixed to the side beam 11. The spring seat 47 protects the axle box 30 so that the coil spring 45 does not come into direct contact with the axle box 30. The flange 424 of the second cylindrical body 42 also functions as the spring seat 47, protecting the side beam 11 (the base portion 111a of the spring cap 111) so that the coil spring 45 does not come into direct contact with the side beam 11.

[0061] Link 48 extends in the longitudinal direction of the bogie 100. Link 48 connects the side beam 11 of the bogie frame 10 to the axle box 30. Rubber bushings 49 are provided at both ends of link 48. Link 48 and rubber bushings 49 support the longitudinal load acting between the bogie frame 10 and the axle box 30 with appropriate rigidity.

[0062] [Operation of the axle box support device] When a railway vehicle is in motion, the axle box 30 vibrates along with the wheelsets 20F and 20R. When the axle box 30 vibrates vertically relative to the bogie frame 10, the first cylindrical body 41, which is fixed to the axle box 30, is displaced vertically relative to the second cylindrical body 42, which is fixed to the side beam 11 of the bogie frame 10. As a result, the group of permanent magnets 43, which are provided on the outer surface 413 of the first cylindrical body 41, are displaced vertically relative to the conductor 44, which is provided on the inner surface 422 of the second cylindrical body 42, thus generating eddy currents in the conductor 44. The interaction between the eddy currents generated in the conductor 44 and the magnetic field (magnetic flux) formed by the group of permanent magnets 43 generates a resistive force (Lorentz force) in the opposite direction to the direction in which the first cylindrical body 41 is displaced relative to the second cylindrical body 42. This resistive force prevents the vertical displacement of the first cylindrical body 41 relative to the second cylindrical body 42. As a result, vertical vibrations of the bogie frame 10 relative to the axle box 30 are dampened.

[0063] [effect] In this embodiment, the sum of the thicknesses of each of the multiple first magnets 431 is greater than or equal to the sum of the thicknesses of each of the multiple second magnets 432. That is, the total thickness of the first magnets 431 having a magnetization direction in the radial direction is greater than or equal to the total thickness of the second magnets 432 having a magnetization direction in the axial direction. Furthermore, at least one of the multiple first magnets 431 is a thick magnet 431a. Because the total thickness of the first magnets 431 is greater than or equal to the total thickness of the second magnets 432, the total amount of magnetic flux emanating radially from the permanent magnet group 43 and the total amount of magnetic flux entering the permanent magnet group 43 are substantially increased.

[0064] In addition, since the thickness of the large magnet 431a is greater than that of the second magnet 432, the surface of the large magnet 431a facing the conductor 44 (outer surface), that is, the surface through which magnetic flux enters and exits, is enlarged. As a result, the influence of the air gap between the first magnet 431 and the conductor 44 on the magnetic flux exiting radially from the first magnet 431 and the magnetic flux entering the first magnet 431 can be reduced, and consequently, the diffusion of magnetic flux in the axial direction caused by the magnetic resistance of the air gap is suppressed.

[0065] Thus, in this embodiment, not only is the total amount of magnetic flux in the radial direction increased, but the diffusion of magnetic flux in the axial direction is also suppressed. Therefore, compared to a configuration in which only a Halbach array is applied, the amount of magnetic flux introduced into the conductor 44 and its magnetic flux density are significantly increased. Accordingly, the axle box support device 40 according to this embodiment can ensure sufficient damping force.

[0066] [Differentiation] In this embodiment, the first cylindrical body 41 is indirectly fixed to the axle box 30 via the support column 46, but it may also be directly fixed to the axle box 30. Furthermore, the spring seat 47 is a separate component from the first cylindrical body 41, but it may be connected to the first cylindrical body 41 or be part of the first cylindrical body 41. For example, referring to Figure 4, the first cylindrical body 41 includes a flange projecting radially outward from its lower end 411. This flange is utilized as the spring seat 47. The first cylindrical body 41 can be fixed to the axle box 30 by utilizing the fact that the coil spring 45 presses the spring seat 47, which is integrated with the first cylindrical body 41, against the axle box 30.

[0067] <Second Embodiment> Figure 5 is an enlarged cross-sectional view of the area around the permanent magnet group 43A in the axle box support device 40A according to the second embodiment. Referring to Figure 5, the configuration of the permanent magnet group 43A in the second embodiment differs from that of the first embodiment. The configuration of the permanent magnet group 43A in the second embodiment will be described in detail below.

[0068] In the permanent magnet group 43A, the multiple first magnets 431 are composed of small-thickness magnets 431b and large-thickness magnets 431a. The small-thickness magnets 431b have a thickness smaller than the thickness of the large-thickness magnets 431a. Here, the large-thickness magnets 431a are constructed by stacking multiple small-thickness magnets 431b in the axial direction. That is, the large-thickness magnets 431a are constructed by stacking small-thickness magnets 431b in the axial direction. The large-thickness magnets 431a have the total thickness of the stacked small-thickness magnets 431b in the axial direction. In this embodiment, the large-thickness magnets 431a are constructed by stacking two small-thickness magnets 431b in the axial direction. In this case, the thickness of the large-thickness magnets 431a is twice the thickness of the small-thickness magnets 431b. In short, the multiple first magnets 431 are composed of four small-thickness magnets 431b.

[0069] The four small-thickness magnets 431b are composed of two inward-facing magnets 431i and two outward-facing magnets 431o. Therefore, the sum of the thicknesses of each inward-facing magnet 431i is equal to the sum of the thicknesses of each outward-facing magnet 431o. In this embodiment, it is preferable that the sum of the thicknesses of one or more inward-facing magnets 431i is equal to the sum of the thicknesses of one or more outward-facing magnets 431o. In this case, with respect to the magnetic flux from the permanent magnet group 43A to the conductor 44, the diffusion of magnetic flux in the axial direction is suppressed. That is, magnetic leakage can be suppressed.

[0070] In the permanent magnet group 43A, each of the multiple second magnets 432 has the same shape as the small thickness magnet 431b. In this embodiment, each of the multiple second magnets 432 is composed of two magnets, and the sum of the thicknesses of each of the multiple second magnets 432 corresponds to the sum of the thicknesses of the two small thickness magnets 431b.

[0071] In this embodiment, the sum of the thicknesses of each of the multiple first magnets 431 is equal to the sum of the thicknesses of four small magnets 431b, and the sum of the thicknesses of each of the multiple second magnets 432 is equal to the sum of the thicknesses of two small magnets 431b. Therefore, the sum of the thicknesses of each of the multiple first magnets 431 is twice the sum of the thicknesses of each of the multiple second magnets 432. As in this embodiment, it is preferable that the sum of the thicknesses of each of the multiple first magnets 431 is twice or more the sum of the thicknesses of each of the multiple second magnets 432. In this case, it is easier to ensure sufficient damping force in the axle box support device 40A.

[0072] In this embodiment, since the large-thick magnet 431a is constructed by stacking multiple small-thick magnets 431b, it is sufficient to prepare multiple small-thick magnets 431b as multiple first magnets 431. Therefore, there is no need to prepare magnets of multiple thicknesses as multiple first magnets 431, and the manufacturing cost of the axle box support device 40A can be reduced.

[0073] Furthermore, in this embodiment, each of the multiple second magnets 432 has the same shape as the small-thickness magnet 431b. Therefore, the first magnet 431 and the second magnet 432 may be manufactured, for example, by preparing magnetic material of the same shape and selecting the magnetization direction as necessary. In this case, there is no need to prepare magnets of multiple shapes for the first and second magnets 431 and 432, and the manufacturing cost of the axle box support device 40A can be further reduced. [Examples]

[0074] The present disclosure will be further described below with reference to examples. However, the present disclosure is not limited to the following examples.

[0075] To confirm the effects of the above embodiment, simulations of axle box support devices equipped with various permanent magnet groups were performed using commercially available magnetic field analysis software (product name: J-MAG, manufactured by JSOL Corporation). In each axle box support device, the configuration other than the permanent magnet group was the same. A Halbach arrangement was applied to the permanent magnet group. The configuration of the permanent magnet group was changed by altering the number of magnets arranged in the axial direction and their magnetization direction. In this embodiment, the material of the axle box, the first cylinder, and the second cylinder was carbon steel. The material of the conductor was pure copper, and each magnet constituting the permanent magnet group was an Nd-B type magnet. The radial dimensions of each magnet were all the same.

[0076] The number of magnets constituting the permanent magnet group was set to 6 to 8. The axial range in which the magnets exist was the same for all permanent magnet groups. Therefore, the thickness of each magnet is obtained by dividing the axial range in which the magnets exist by the number of magnets. The more magnets there are, the smaller the thickness of each magnet. Axisymmetric time history response analysis was performed on eight different permanent magnet group configurations. In the analysis, a conductor was vibrated relative to the permanent magnet group, and the damping coefficient of the vibration in the axle box support device was calculated. The amplitude of the vibration was ±0.5 mm. The vibration frequencies were 1 Hz and 5 Hz.

[0077] Figures 5 to 12 show the configurations of permanent magnet groups 43A and 143. In Figures 6 to 12, the magnetization direction is indicated by arrows, similar to Figure 5. Figures 6, 7, and 8 show the configurations of Comparative Examples 1-1, 1-2, and 1-3, respectively. In Comparative Examples 1-1, 1-2, and 1-3, the sum of the thicknesses of the magnets with a radial magnetization direction (first magnets) is greater than or equal to the sum of the thicknesses of the magnets with an axial magnetization direction (second magnets), and there are no inward-facing or outward-facing magnets (thick magnets) that are continuously arranged in the axial direction. Comparative Examples 1-1, 1-2, and 1-3 differ in the number of magnets. Comparative Example 1-1 has 6 magnets, Comparative Example 1-2 has 7 magnets, and Comparative Example 1-3 has 8 magnets.

[0078] Figure 9 shows the configuration of Comparative Example 2. In Comparative Example 2, the sum of the thicknesses of the first magnets is less than the sum of the thicknesses of the second magnets, and there are no extra-thick magnets. In Comparative Example 2, there are 7 magnets.

[0079] Figures 10 and 11 show the configurations of Invention Example 1-1 and Invention Example 1-2, respectively. In Invention Examples 1-1 and 1-2, the sum of the thicknesses of the first magnets is greater than or equal to the sum of the thicknesses of the second magnets, and there are large-thick magnets. Furthermore, in Invention Examples 1-1 and 1-2, the sum of the thicknesses of the inward-facing magnets among the first magnets is different from the sum of the thicknesses of the outward-facing magnets. Invention Example 1-1 has 7 magnets, and Invention Example 1-2 has 8 magnets.

[0080] Figures 5 and 12 show the configurations of Invention Example 2-1 and Invention Example 2-2, respectively. In Invention Examples 2-1 and 2-2, the sum of the thicknesses of the first magnets is greater than or equal to the sum of the thicknesses of the second magnets, and there are large-thick magnets. Furthermore, in Invention Examples 2-1 and 2-2, the sum of the thicknesses of the inward-facing magnets among the first magnets is equal to the sum of the thicknesses of the outward-facing magnets. Invention Example 2-1 has 6 magnets, and Invention Example 2-2 has 8 magnets.

[0081] Figures 13 and 14 show the vibration damping coefficients for the above-described example of the present invention and the above-described comparative example, respectively. In Figures 13 and 14, the horizontal axis represents the number of magnets, and the vertical axis represents the normalized damping coefficient. The normalized damping coefficient is the ratio [-] of the damping coefficient in the configuration of each permanent magnet group 43A,143 to the damping coefficient in the configuration of permanent magnet group 143 of Comparative Example 1-1. Figure 13 is a diagram when the vibration frequency is 1 Hz, and Figure 14 is a diagram when the vibration frequency is 5 Hz.

[0082] Referring to Figure 13, when the number of magnets is 6, the normalized damping coefficient decreases in the order of Invention Example 2-1 and Comparative Example 1-1. When the number of magnets is 7, the normalized damping coefficient decreases in the order of Invention Example 1-1, Comparative Example 1-2, and Comparative Example 2. When the number of magnets is 8, the normalized damping coefficient decreases in the order of Invention Example 1-2, Invention Example 2-2, and Comparative Example 1-3. Therefore, for any number of magnets, by having the permanent magnet groups 43A and 143 adopt the configuration of the Invention Example, a damping force can be secured more than that of the Comparative Examples. In other words, it has been shown that a sufficient damping force can be secured in the axle box support device by having a configuration in which at least one of the multiple first magnets has a thickness greater than the thickness of each of the multiple second magnets.

[0083] Furthermore, when comparing the configurations of the present invention examples, the normalized damping coefficient was larger in the configurations of the present invention examples 1-1, 1-2, and 2-1 than in the configuration of the present invention example 2-2. In the present invention example 2-2, the sum of the individual thicknesses of the multiple first magnets was the same as the sum of the individual thicknesses of the multiple second magnets. In contrast, in the present invention examples 1-1, 1-2, and 2-1, the sum of the individual thicknesses of the multiple first magnets was more than twice the sum of the individual thicknesses of the multiple second magnets. From this, it was found that when the sum of the individual thicknesses of the multiple first magnets is more than twice the sum of the individual thicknesses of the multiple second magnets, it is easier to secure sufficient damping force in the axle box support device.

[0084] Furthermore, when the number of magnets was 7, the normalized damping coefficient of Comparative Example 2 was smaller than that of Comparative Examples 1-2, suggesting that the damping force may decrease if the sum of the thicknesses of the first magnets is less than the sum of the thicknesses of the second magnets.

[0085] In Figure 14, a similar trend to that in Figure 13 can be observed with respect to the normalized damping coefficient. Therefore, in both the low-frequency ranges of 1 Hz and 5 Hz, the configuration of the present invention ensures sufficient damping force in the axle box support device.

[0086] Figures 15 to 18 show the magnetic flux density distribution around the permanent magnet group 43A when the permanent magnet group 43A is stationary during the analysis. Figures 15 to 18 show a simplified configuration around the permanent magnet group 43A, with the support column 46 and the first cylindrical body 41 shown as a single unit.

[0087] Figure 15 shows the magnetic flux density distribution around the permanent magnet group 43A corresponding to the configuration of Example 1-1 of the present invention shown in Figure 10. Figure 16 shows the magnetic flux density distribution around the permanent magnet group 43A corresponding to the configuration of Example 1-2 of the present invention shown in Figure 11. Figure 17 shows the magnetic flux density distribution around the permanent magnet group 43A corresponding to the configuration of Example 2-1 of the present invention shown in Figure 5. Figure 18 shows the magnetic flux density distribution around the permanent magnet group 43A corresponding to the configuration of Example 2-2 of the present invention shown in Figure 12.

[0088] In Figures 15 to 18, darker shading indicates higher magnetic flux density, and lighter shading indicates lower magnetic flux density. Comparing Figures 17 and 18 with Figures 15 and 16, the magnetic flux in Invention Examples 2-1 and 2-2 shows less axial diffusion than the magnetic flux in Invention Examples 1-1 and 1-2. From this, it can be seen that the axial diffusion of magnetic flux from the permanent magnet group 43A can be suppressed by a configuration in which the sum of the thicknesses of the inward-facing magnets of the first magnet is equal to the sum of the thicknesses of the outward-facing magnets.

[0089] Figures 16 and 18 show examples of magnetic circuits (magnetic flux loops). Magnetic flux loops are usually formed between adjacent magnets, as shown in Figure 18 (Example 2-2 of the present invention). However, for example, in the case of Figure 16 (Example 1-2 of the present invention), magnetic flux that does not form a loop with adjacent magnets among the radially outward-facing magnetic flux returns to its own magnet. At that time, it is affected by the magnetic resistance of the air gap between the first cylindrical body 41 and the conductor 44, causing the magnetic flux to diffuse far in the axial direction. Thus, in the case where the sum of the thicknesses of the inward-facing magnets among the first magnets is equal to the sum of the thicknesses of the outward-facing magnets, it is thought that the diffusion of magnetic flux in the axial direction from the permanent magnet group 43A can be suppressed.

[0090] While embodiments relating to this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible as long as they do not deviate from its spirit.

[0091] In the above embodiment, the first cylindrical body 41 is fixed to the axle box 30, and the second cylindrical body 42 is positioned outside the first cylindrical body 41 and fixed to the side beam 11. However, the first cylindrical body 41 may be fixed to the side beam 11, and the second cylindrical body 42 may be positioned outside the first cylindrical body 41 and fixed to the axle box 30.

[0092] Alternatively, the first cylindrical body 41 may be fixed to the shaft box 30, and the second cylindrical body 42 may be positioned inside the first cylindrical body 41 and fixed to the side beam 11. In this case, the permanent magnet groups 43, 43A are held on the inner circumferential surface 412 of the first cylindrical body 41, and the conductor 44 is provided on the outer circumferential surface 423 of the second cylindrical body 42.

[0093] Alternatively, the first cylindrical body 41 may be fixed to the side beam 11, and the second cylindrical body 42 may be positioned inside the first cylindrical body 41 and fixed to the shaft box 30. In this case as well, the permanent magnet groups 43, 43A are held on the inner circumferential surface 412 of the first cylindrical body 41, and the conductor 44 is provided on the outer circumferential surface 423 of the second cylindrical body 42.

[0094] In the above embodiment, the coil spring 45 is located outside the first cylindrical body 41 and the second cylindrical body 42, but the coil spring 45 may also be located inside the first cylindrical body 41 and the second cylindrical body 42. [Explanation of symbols]

[0095] 100: Dolly 10: Bogie frame 30: Axle box 40,40A: Axle box support device 41: First cylinder 412: Inner surface 413: Outer surface 42: Second cylinder 422: Inner surface 423: Outer surface 43,43A: Permanent magnet group 431: The First Magnet 431a: Large Thick Magnet 431b: Small thickness magnet 431i: Inward-facing magnet 431o: Outward-facing magnet 432: The second magnet 44: Conductors 45: Coil spring

Claims

1. An axle box support device that holds the axle box relative to the bogie frame, A first cylindrical body made of magnetic material and having a central axis extending in the vertical direction, the first cylindrical body being positioned between the side beam of the bogie frame and the axle box, and fixed to either the side beam or the axle box, A second cylindrical body made of magnetic material and having a central axis extending in the vertical direction, the second cylindrical body being arranged coaxially with the first cylindrical body either inside or outside the first cylindrical body and fixed to the other side beam and the shaft box, A group of permanent magnets held on the inner and outer circumferential surfaces of the first cylindrical body, specifically on the circumferential surface on the side of the second cylindrical body, and arranged in a Halbach arrangement along the axial direction of the first cylindrical body, the group of permanent magnets comprising a plurality of first magnets having a magnetization direction in the radial direction of the first cylindrical body, and a plurality of second magnets having a magnetization direction in the axial direction, A conductor is provided on the inner and outer circumferential surfaces of the second cylindrical body, specifically on the circumferential surface on the side facing the first cylindrical body, opposite to the group of permanent magnets. A coil spring is positioned on the axle box, coaxially with the first and second cylindrical bodies, either inside or outside the first and second cylindrical bodies, and supports the side beam of the bogie frame. Equipped with, If we define the axial dimension of each of the plurality of first magnets and the plurality of second magnets as the thickness, At least one of the plurality of first magnets is a thick magnet having a thickness greater than the thickness of each of the plurality of second magnets. Axle box support device in which the sum of the thicknesses of each of the plurality of first magnets is equal to or greater than the sum of the thicknesses of each of the plurality of second magnets.

2. A shaft box support device according to claim 1, The plurality of first magnets are composed of one or more inward-facing magnets whose magnetization direction is inward in the radial direction, and one or more outward-facing magnets whose magnetization direction is outward in the radial direction. A shaft box support device wherein the sum of the thicknesses of each of the one or more inward-facing magnets is equal to the sum of the thicknesses of each of the one or more outward-facing magnets.

3. A shaft box support device according to claim 1, Axle box support device in which the sum of the thicknesses of each of the plurality of first magnets is at least twice the sum of the thicknesses of each of the plurality of second magnets.

4. A shaft box support device according to claim 1, The plurality of first magnets are composed of small-thickness magnets having a thickness smaller than the thickness of the large-thickness magnet, and the large-thickness magnet. The aforementioned large-thick magnet is a shaft box support device formed by stacking a plurality of the aforementioned small-thick magnets in the axial direction.

5. A shaft box support device according to claim 4, A shaft box support device wherein each of the plurality of second magnets has the same shape as the small-thickness magnet.

6. A shaft box support device according to claim 1, The first cylindrical body is fixed to the shaft box, The second cylindrical body is positioned outside the first cylindrical body and fixed to the side beam. The group of permanent magnets is held on the outer surface of the first cylindrical body, The conductor is provided on the inner circumferential surface of the second cylindrical body, The coil spring is an axle box support device positioned on the outside of the first cylindrical body and the second cylindrical body.

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