Axle box suspension

Abstract

An axle box suspension (40) is provided with a coil spring (41), a first cylindrical body (42), a second cylindrical body (43), a plurality of permanent magnets (44), and a conductive film (45). The coil spring (41) is disposed on an axle box (30) and supports a side beam (11) of a truck frame (10). The first cylindrical body (42) is disposed coaxially with the coil spring (41) on the outside of the coil spring (41). The second cylindrical body (43) is disposed coaxially with the coil spring (41) on the outside of the coil spring (41) and on the inside or outside of the first cylindrical body (42). The plurality of permanent magnets (44) are held on the peripheral surface of the first cylindrical body (42). The conductive film (45) is provided to the peripheral surface of the second cylindrical body (43) so as to face the permanent magnets (44).

Description

Axle box support device

[0001] The present disclosure relates to axle box supports, and more particularly to axle box supports for railway vehicles.

[0002] In railway vehicles, axle box suspensions are used to hold axle boxes on the bogie frame. The axle box suspensions include axle springs as their main elements. The axle springs are arranged on the axle boxes to elastically support the bogie frame. Coil springs are generally used for the axle springs. The axle box suspensions are usually equipped with a vibration damping mechanism. Vibrations transmitted from the axle boxes to the bogie frame when the railway vehicle is running are damped by the vibration damping mechanism. For example, oil dampers, high-damping rubber, etc. are used for the vibration damping mechanism.

[0003] Japanese Patent Laid-Open Publication No. 11-94008 (Patent Document 1) and Japanese Utility Model Laid-Open Publication No. 6-23864 (Patent Document 2) disclose axle box suspensions equipped with coil springs and vibration damping mechanisms to damp vibrations, particularly in the vertical direction. The axle box suspensions in Patent Document 1 include a fluid-filled mount as the vibration damping mechanism. The fluid-filled mount is disposed inside the coil spring. Specifically, in the fluid-filled mount, a damping plate connected to the bogie frame is immersed in a highly viscous liquid in a case attached to the axle box. When the bogie frame vibrates vertically relative to the axle box, the damping plate agitates the highly viscous liquid, thereby damping the vertical vibration of the bogie frame relative to the axle box.

[0004] The axle box support device of Patent Document 2 is equipped with a cylindrical roll rubber as a vibration damping mechanism. The roll rubber is arranged inside a coil spring. Specifically, the roll rubber is fitted in the space between a roll rubber bearing outer cylinder connected to the bogie frame and a roll rubber bearing inner cylinder connected to the axle box so that it can freely roll and displace. When the bogie frame vibrates in the vertical direction relative to the axle box, the roll rubber elastically deforms, thereby damping the vertical vibration of the bogie frame relative to the axle box.

[0005] In these axle box support devices, the vibration damping mechanism is placed inside the coil spring, and a liquid-filled mount or rolled rubber is used as the vibration damping mechanism. In the case of a liquid-filled mount, there is a risk of liquid leakage and deterioration of the oil over time, while in the case of rolled rubber, there is deterioration of the rubber over time. The deterioration of the oil or rubber over time can degrade the damping performance of the vibration damping mechanism. Therefore, in both of the axle box support devices of 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 regular maintenance.

[0006] In contrast to such an axle box suspension, Japanese Patent Application Laid-Open Publication No. 2023-177124 (Patent Document 3) proposes an axle box suspension equipped with an upper and lower damping mechanism that generates upper and lower damping forces through eddy current resistance as a vibration damping mechanism. The upper and lower damping mechanisms are arranged inside the coil springs. Specifically, the upper and lower damping mechanisms include an outer cylinder arranged above the axle box and an inner cylinder extending from the bogie frame toward the axle box and positioned inside the outer cylinder. A conductor is arranged on the inner peripheral surface of the outer cylinder, and ring-shaped permanent magnets are arranged in multiple stages on the outer peripheral surface of the inner cylinder so as to face the conductor. When relative vertical displacement occurs between the axle box and the bogie frame, eddy currents are generated in the conductor arranged in the outer cylinder. In other words, the conductor serves as an eddy current generator. The interaction between the eddy currents generated in the eddy current generator and the magnetic field generated by the permanent magnets generates a resistance force (Lorentz force) in the opposite direction to the direction of relative displacement of the inner cylinder with respect to the outer cylinder, thereby preventing relative displacement of the inner cylinder with respect to the outer cylinder. As a result, vertical vibration of the bogie frame relative to the axle box is damped. The permanent magnets and conductors that make up the vibration damping mechanism are independent and do not come into contact with each other, so they are less likely to deteriorate over time. Therefore, the axle box support device of Patent Document 3 can reduce the need for regular maintenance.

[0007] Japanese Patent Application Laid-Open No. 11-94008 Japanese Utility Model Application Laid-Open No. 6-23864 Japanese Patent Application Laid-Open No. 2023-177124

[0008] In the axle box suspension device of Patent Document 3, the vibration damping mechanism (vertical damping mechanism) is composed of a permanent magnet and an electric conductor (eddy current generator). While a damping force is generated in response to the relative vertical displacement between the axle box and the bogie frame, the eddy current generator generates heat due to eddy currents. In the axle box suspension device of Patent Document 3, the vibration damping mechanism, i.e., the eddy current generator and permanent magnet, are disposed inside a coil spring and isolated from the outside by the coil spring. In this case, when the railcar is running, the wind flowing around the axle box suspension device is prevented from reaching the eddy current generator by the coil spring. This may result in insufficient cooling performance for the eddy current generator. If the cooling performance for the eddy current generator is insufficient, for example, if a high damping force is generated for a long period of time, the temperature of the eddy current generator may rise excessively, resulting in a decrease in the conductivity of the eddy current generator. Furthermore, if the temperature of the eddy current generator rises excessively, the permanent magnet facing the eddy current generator may be excessively heated due to heat transfer from the eddy current generator or via airflow, potentially reducing the magnetic force of the permanent magnet. A decrease in the electrical conductivity of the eddy current generating portion and a decrease in the magnetic force of the permanent magnet both result in a decrease in the damping force of the upper and lower damping mechanisms.

[0009] The present disclosure provides an axle box support device that has an eddy current generating section for damping vertical vibration of a bogie frame relative to an axle box and that can ensure cooling performance for the eddy current generating section.

[0010] The axle box support device according to the present disclosure holds an axle box relative to a bogie frame. The axle box support device includes a coil spring, a first cylindrical body, a second cylindrical body, multiple permanent magnets, and a conductive film. The coil spring is disposed on the axle box and supports a side beam of the bogie frame. The first cylindrical body is magnetic. The first cylindrical body is disposed coaxially with the coil spring on the outer side of the coil spring. The first cylindrical body is fixed to one of the side beam and the axle box. The second cylindrical body is magnetic. The second cylindrical body is disposed coaxially with the coil spring on the outer side of the coil spring and on the inner or outer side of the first cylindrical body. The second cylindrical body is fixed to the other of the side beam and the axle box. The multiple permanent magnets are held on the circumferential surface of the first cylindrical body that faces the second cylindrical body. The permanent magnets are arranged along the axial direction of the first cylindrical body. The conductive film is provided on one of the inner and outer circumferential surfaces of the second cylindrical body, the circumferential surface facing the first cylindrical body, facing the permanent magnet.

[0011] According to the axle box support device of the present disclosure, cooling performance for eddy current generating parts can be ensured.

[0012] Fig. 1 is a top view of a bogie provided with an axle box support device according to a first embodiment. Fig. 2 is a cross-sectional view showing a schematic configuration of the axle box support device according to the first embodiment. Fig. 3 is a cross-sectional view showing a schematic configuration of a modified axle box support device according to the first embodiment. Fig. 4 is a cross-sectional view showing a schematic configuration of an axle box support device according to a second embodiment. Fig. 5 is a cross-sectional view showing a schematic configuration of a modified axle box support device according to the second embodiment. Fig. 6 is a cross-sectional view showing a schematic configuration of an axle box support device according to a third embodiment. Fig. 7 is a cross-sectional view showing a schematic configuration of an axle box support device according to a fourth embodiment. Fig. 8 is a diagram showing an example in which a plurality of permanent magnets are arranged in a Halbach array.

[0013] An axle box support device according to an embodiment holds an axle box relative to a bogie frame. The axle box support device includes a coil spring, a first cylindrical body, a second cylindrical body, multiple permanent magnets, and a conductive film. The coil spring is disposed on the axle box and supports a side beam of the bogie frame. The first cylindrical body is magnetic. The first cylindrical body is disposed coaxially with the coil spring on the outside of the coil spring. The first cylindrical body is fixed to one of the side beam and the axle box. The second cylindrical body is magnetic. The second cylindrical body is disposed coaxially with the coil spring on the outside of the coil spring and on the inside or outside of the first cylindrical body. The second cylindrical body is fixed to the other of the side beam and the axle box. Multiple permanent magnets are held on the circumferential surface of the first cylindrical body that faces the second cylindrical body, out of the inner and outer circumferential surfaces. The permanent magnets are arranged along the axial direction of the first cylindrical body. The conductive film is provided on one of the inner and outer circumferential surfaces of the second cylindrical body, the circumferential surface facing the first cylindrical body, facing the permanent magnet (first configuration).

[0014] In the axle box support device according to the first configuration, the first and second cylindrical bodies are both magnetic and arranged coaxially with the coil spring. One of the first and second cylindrical bodies is fixed to a side beam of the bogie frame, and the other is fixed to the axle box. A plurality of permanent magnets are held on the circumferential surface of the first cylindrical body facing the second cylindrical body, and a conductive film is provided on the circumferential surface of the second cylindrical body facing the first cylindrical body, facing the permanent magnets. That is, the permanent magnets held on the first cylindrical body face the conductive film provided on the second cylindrical body. In this case, when the bogie frame vibrates vertically with respect to the axle box, the first cylindrical body is displaced vertically relative to the second cylindrical body, and as a result, the permanent magnets are displaced vertically relative to the conductive film. This generates eddy currents in the conductive film. That is, the conductive film provided on the second cylindrical body serves as an eddy current generator. The interaction between the eddy currents generated in the conductive film (eddy current generating portion) and the magnetic field generated by the permanent magnet generates a resistance force (Lorentz force) in the opposite direction to the direction of relative displacement of the first cylinder with respect to the second cylinder, preventing the relative displacement of the first cylinder with respect to the second cylinder, thereby damping the vertical vibration of the bogie frame with respect to the axle box.

[0015] Furthermore, in the axle box support device according to the first configuration, the first and second cylindrical bodies are arranged outside the coil spring. One of the first and second cylindrical bodies is an external cylindrical body arranged radially outside, and the other is an internal cylindrical body arranged radially inside. The permanent magnet and the conductive film are provided between the external cylindrical body and the internal cylindrical body. When the external cylindrical body is fixed to the side beam, the lower end of the external cylindrical body is open. In this case, when the railway vehicle is traveling, running wind is introduced into the space between the external cylindrical body and the internal cylindrical body from the lower end of the external cylindrical body. On the other hand, when the external cylindrical body is fixed to the axle box, the upper end of the external cylindrical body is open. In this case, when the railway vehicle is traveling, running wind is introduced into the space between the external cylindrical body and the internal cylindrical body from the upper end of the external cylindrical body. In either case, the running wind introduced into the space between the external cylindrical body and the internal cylindrical body can effectively cool the conductive film and can also effectively cool the permanent magnet. Therefore, according to the axle box support device of the first configuration, it is possible to ensure the cooling performance for the eddy current generating portion (conductive film).

[0016] In the axle box support device according to the first configuration, preferably, the first cylindrical body is fixed to the axle box, and the second cylindrical body is disposed outside the first cylindrical body and fixed to the side beam. In this case, the plurality of permanent magnets are held on the outer peripheral surface of the first cylindrical body, and the conductive film is provided on the inner peripheral surface of the second cylindrical body (second configuration).

[0017] In the second configuration, the first cylindrical body that holds the permanent magnet is an inner cylindrical body that is fixed to the axle box. The second cylindrical body that is provided with the conductive film (eddy current generator) is an outer cylindrical body that is fixed to the side beam. Therefore, the lower end of the second cylindrical body, which is the outer cylindrical body, is open. In this case, when the railway vehicle is running, running wind is introduced from the lower end of the second cylindrical body into the space between the inner surface of the second cylindrical body and the outer surface of the first cylindrical body. The introduced running wind can effectively cool the conductive film provided on the inner surface of the second cylindrical body, and can also effectively cool the permanent magnet held on the outer surface of the first cylindrical body.

[0018] In the axle box support according to the second configuration, a spring cap including a cylindrical side plate portion arranged coaxially with the coil spring may be provided at the longitudinal end of the side beam, in which case the side plate portion of the spring cap preferably constitutes the second cylindrical body (third configuration).

[0019] In the third configuration, when the railway vehicle is running, the wind from the running wind also directly hits the outer circumferential surface of the second cylindrical body. This promotes cooling of the second cylindrical body itself, on which the conductive film is provided, making it possible to more effectively cool the conductive film. Furthermore, in the third configuration, the side plate portion of the spring cap constitutes the second cylindrical body, eliminating the need to prepare the second cylindrical body separately, and reducing the number of parts. Furthermore, the reduced number of parts allows for reduced costs.

[0020] In the axle box support device according to the first configuration, preferably, the first cylindrical body is fixed to the side beam, and the second cylindrical body is disposed inside the first cylindrical body and fixed to the axle box. In this case, the plurality of permanent magnets are held on the inner peripheral surface of the first cylindrical body, and the conductive film is provided on the outer peripheral surface of the second cylindrical body (fourth configuration).

[0021] In the fourth configuration, the first cylindrical body that holds the permanent magnet is an outer cylindrical body and is fixed to the side beam. The second cylindrical body that is provided with a conductive film (eddy current generator) is an inner cylindrical body and is fixed to the axle box. Therefore, the lower end of the first cylindrical body, which is the outer cylindrical body, is open. In this case, when the railway vehicle is running, running wind is introduced from the lower end of the first cylindrical body into the space between the inner surface of the first cylindrical body and the outer surface of the second cylindrical body. The introduced running wind can effectively cool the conductive film provided on the outer surface of the second cylindrical body, and can also effectively cool the permanent magnet held on the inner surface of the first cylindrical body.

[0022] In the axle box support according to the fourth configuration, a spring cap including a cylindrical side plate portion arranged coaxially with the coil spring may be provided at a longitudinal end of the side beam, and in this case, the side plate portion of the spring cap preferably constitutes the first cylindrical body (fifth configuration).

[0023] In the fifth configuration, when the railway vehicle is running, the wind blows directly against the outer circumferential surface of the first cylindrical body. This promotes cooling of the first cylindrical body itself, which houses the permanent magnet, enabling more effective cooling of the permanent magnet. Furthermore, in the fifth configuration, the side plate portion of the spring cap constitutes the first cylindrical body, eliminating the need to prepare the first cylindrical body separately, thereby reducing the number of parts. Furthermore, the reduced number of parts contributes to reducing the cost of the parts.

[0024] In the axle box support device according to the first configuration, preferably, the first cylindrical body is fixed to the axle box, and the second cylindrical body is disposed inside the first cylindrical body and fixed to the side beam. In this case, the plurality of permanent magnets are held on the inner peripheral surface of the first cylindrical body, and the conductive film is provided on the outer peripheral surface of the second cylindrical body (sixth configuration).

[0025] In the sixth configuration, the first cylindrical body that holds the permanent magnet is an outer cylindrical body and is fixed to the axle box. The second cylindrical body that is provided with the conductive film (eddy current generator) is an inner cylindrical body and is fixed to the side beam. Therefore, the upper end of the first cylindrical body, which is the outer cylindrical body, is open. In this case, when the railway vehicle is running, running wind is introduced from the upper end of the first cylindrical body into the space between the inner surface of the first cylindrical body and the outer surface of the second cylindrical body. The introduced running wind can effectively cool the conductive film provided on the outer surface of the second cylindrical body, and can also effectively cool the permanent magnet held on the inner surface of the first cylindrical body.

[0026] In the axle box support device according to the first configuration, preferably, the first cylindrical body is fixed to the side beam, and the second cylindrical body is disposed outside the first cylindrical body and fixed to the axle box. In this case, the plurality of permanent magnets are held on the outer peripheral surface of the first cylindrical body, and the conductive film is provided on the inner peripheral surface of the second cylindrical body (seventh configuration).

[0027] In the seventh configuration, the first cylindrical body holding the permanent magnet is an inner cylindrical body and is fixed to the side beam. The second cylindrical body on which the conductive film (eddy current generator) is provided is an outer cylindrical body and is fixed to the axle box. Therefore, the upper end of the second cylindrical body, which is the outer cylindrical body, is open. In this case, when the railway vehicle is running, running wind is introduced from the upper end of the second cylindrical body into the space between the inner surface of the second cylindrical body and the outer surface of the first cylindrical body. The introduced running wind can effectively cool the conductive film provided on the inner surface of the second cylindrical body, and can also effectively cool the permanent magnet held on the outer surface of the first cylindrical body.

[0028] The axle box support device according to the fourth or seventh configuration may have the following configuration: the first cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side; the first cylindrical body includes a first flange protruding radially inward from the upper end of the first cylindrical body; the second cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side; the second cylindrical body includes a second flange protruding radially inward from the lower end of the second cylindrical body; and the coil spring is interposed between the first flange and the second flange (eighth configuration).

[0029] In the eighth configuration, a first cylindrical body including a first flange at its upper end is fixed to the side beam, and a second cylindrical body including a second flange at its lower end is fixed to the axle box. In this case, because a coil spring is interposed between the first flange and the second flange, the first flange and the second flange are subjected to the elastic repulsive force of the coil spring. As a result, the coil spring presses the first flange toward the side beam and the second flange toward the axle box. Due to this elastic repulsive force of the coil spring, the first cylindrical body is pressed against the side beam and fixed thereto, and the second cylindrical body is pressed against the axle box and fixed thereto. Therefore, mechanical joining, such as welding, is not required to fix the first cylindrical body to the side beam and the second cylindrical body to the axle box. This allows for efficient assembly of the axle box support device.

[0030] The axle box support device according to the second or sixth configuration can have the following configuration: the first cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side. The first cylindrical body includes a first flange protruding radially inward from the lower end of the first cylindrical body. The second cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side. The second cylindrical body includes a second flange protruding radially inward from the upper end of the second cylindrical body. The coil spring is interposed between the first flange and the second flange (ninth configuration).

[0031] In the ninth configuration, a first cylindrical body including a first flange at its lower end is fixed to the axle box, and a second cylindrical body including a second flange at its upper end is fixed to the side beam. In this case, because a coil spring is interposed between the first flange and the second flange, the first flange and the second flange are subjected to the elastic repulsive force of the coil spring. As a result, the coil spring presses the first flange toward the axle box and the second flange toward the side beam. Due to this elastic repulsive force of the coil spring, the first cylindrical body is pressed against the axle box and fixed to the axle box, and the second cylindrical body is pressed against the side beam and fixed to the side beam. Therefore, mechanical joining, such as welding, is not required to fix the first cylindrical body to the axle box and the second cylindrical body to the side beam. This allows for efficient assembly of the axle box support device.

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or equivalent components are designated by the same reference numerals, and the same description will not be repeated.

[0033] <First embodiment> An axle box suspension device according to this embodiment is used in a railway vehicle. The railway vehicle includes a bogie and a car body. The bogies are usually arranged at the front and rear of the car body. The car body is supported by a pair of left and right air springs arranged on each bogie. Generally, a plurality of cars are coupled together and run on rails. In such a railway vehicle, the axle box suspension device is provided on the bogie. First, a bogie including an axle box suspension device according to this embodiment will be described below.

[0034] [Configuration of bogie] Fig. 1 is a top view of a bogie 100 provided with an axle box suspension device according to the first embodiment. The bogie 100 includes a bogie frame 10, two wheel sets 20F, 20R, four axle boxes 30, and four axle box suspension devices 40. The bogie 100 is a bolsterless bogie. In this specification, the running direction of the bogie 100, i.e., the direction along the rails, may be referred to as the fore-aft direction or longitudinal direction. Furthermore, the direction perpendicular to the running direction of the bogie 100, i.e., the direction vertically spanning the rails, may be referred to as the left-right direction or width direction. The direction perpendicular to the fore-aft direction and left-right direction may be referred to as the up-down direction or vertical direction.

[0035] The bogie frame 10 is a main structural frame constituting 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 longitudinal 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 beams 12. In this embodiment, the side beams 11 are provided with spring caps 111 at their longitudinal ends. The spring cap 111 includes a disk-shaped base portion 111a and a cylindrical side plate portion 111b. The side plate portion 111b is continuous with the base portion 111a and extends downward from the outer periphery of the base portion 111a. However, the location of the spring cap 111 is not limited to the longitudinal end of the side beam 11. For example, the spring cap 111 may be located in the longitudinal center of the side beam 11.

[0036] The wheel sets 20F, 20R are disposed on the front and rear sides of the bogie 100, respectively. The wheel sets 20F, 20R are supported by the bogie frame 10. Each of the wheel sets 20F, 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 disposed on both the left and right sides of the axle 22 and are fixed to the axle 22. Axle boxes 30 are provided on the axle 22 outside the wheels 21. The axle 22, i.e., the wheel sets 20F, 20R, are supported by the axle boxes 30 so as to be rotatable about their axes.

[0037] The spring caps 111 of the side beams 11 are disposed above the axle box 30. The axle box support devices 40 are disposed on top of the axle box 30. The axle box support devices 40 hold the axle box 30 against the bogie frame 10 (side beams 11).

[0038] [Configuration of the Axle Box Support Device] The axle box support device 40 of 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 up-down direction by a coil spring (axle spring), and the axle box 30 and the side beam 11 are further elastically connected in the front-to-rear direction by a link. However, the axle box support device 40 of this embodiment may be an axle box support device other than a monolink type.

[0039] 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 a cross-section taken along line II-II in Figure 1. As shown in Figure 2, the axle box support device 40 includes a coil spring 41, a first cylindrical body 42, a second cylindrical body 43, a plurality of permanent magnets 44, and a conductive film 45. The axle box support device 40 of this embodiment further includes a link 46 and a rubber bushing 47.

[0040] The coil spring 41 is disposed on the axle box 30 and supports the side beam 11 of the bogie frame 10. The coil spring 41 is a spring formed by forming a wire or rod-shaped material into a spiral shape. The central axis X of the coil spring 41 extends in the vertical direction. The coil spring 41 includes an upper end 411 on the upper side in the vertical direction and a lower end 412 on the lower side in the vertical direction. The coil spring 41 has an elastic support function in the vertical direction. In this specification, the direction in which the central axis X of the coil spring 41 extends is sometimes referred to as the axial direction, and the direction perpendicular to the axial direction is sometimes referred to as the radial direction.

[0041] The first cylindrical body 42 has a cylindrical shape and extends in the vertical direction. The first cylindrical body 42 has an upper end 421 located on the side beam 11 side and a lower end 422 located on the axle box 30 side. The first cylindrical body 42 also has an inner circumferential surface 423 on the radially inner side and an outer circumferential surface 424 on the radially outer side. In this embodiment, the first cylindrical body 42 further includes a first flange 425 that protrudes radially inward from the lower end 422 of the first cylindrical body 42.

[0042] The first cylindrical body 42 is disposed coaxially with the coil spring 41 on the outer side of the coil spring 41. That is, the central axis of the first cylindrical body 42 substantially coincides with the central axis X of the coil spring 41.

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

[0044] The first cylindrical body 42 is fixed to one of the side beams 11 and the axle box 30. In this embodiment, the first cylindrical body 42 is fixed to the axle box 30. Specifically, the lower end portion 422 and the first flange 425 of the first cylindrical body 42 are fixed in contact with the upper surface of the axle box 30.

[0045] The second cylindrical body 43 has a cylindrical shape similar to the first cylindrical body 42 and extends in the vertical direction. The second cylindrical body 43 has an upper end 431 located on the side beam 11 side and a lower end 432 located on the axle box 30 side. The second cylindrical body 43 also has an inner circumferential surface 433 on the radially inner side and an outer circumferential surface 434 on the radially outer side. In this embodiment, the second cylindrical body 43 further includes a second flange 435 that protrudes radially inward from the upper end 431 of the second cylindrical body 43.

[0046] The second cylindrical body 43 is arranged coaxially with the coil spring 41 outside the coil spring 41 and inside or outside the first cylindrical body 42. That is, the central axis of the second cylindrical body 43 substantially coincides with the central axis X of the coil spring 41. In this embodiment, the second cylindrical body 43 is arranged outside the first cylindrical body 42. In other words, the coil spring 41, the first cylindrical body 42, and the second cylindrical body 43 are arranged concentrically in this order from the central axis X toward the radially outward direction. In this case, the first cylindrical body 42 is arranged radially inside, and the second cylindrical body 43 is arranged radially outside. Therefore, in this embodiment, the first cylindrical body 42 is an inner cylindrical body, and the second cylindrical body 43 is an outer cylindrical body. Therefore, the outer peripheral surface 424 of the first cylindrical body 42 faces the inner peripheral surface 433 of the second cylindrical body 43.

[0047] The second cylindrical body 43 is fixed to the other of the side beam 11 and the axle box 30. That is, the second cylindrical body 43 is fixed to one of the side beam 11 and the axle box 30 to which the first cylindrical body 42 is not fixed. In this embodiment, since the first cylindrical body 42 is fixed to the axle box 30, the second cylindrical body 43 is fixed to the side beam 11. Specifically, the upper end portion 431 and the second flange 435 of the second cylindrical body 43 are fixed in contact with the lower surface of the base portion 111a of the spring cap 111 of the side beam 11.

[0048] In this embodiment, the outer peripheral surface 434 of the second cylindrical body 43 is in close radial contact with the side plate portion 111b of the spring cap 111 of the side beam 11. The side plate portion 111b of the spring cap 111 is disposed coaxially with the coil spring 41.

[0049] The second cylindrical body 43 is magnetic and is made of a ferromagnetic material such as carbon steel or cast steel.

[0050] The coil spring 41 is interposed between a first flange 425 and a second flange 435. In this embodiment, the first flange 425 is provided at a lower end 422 of the first cylindrical body 42, and the second flange 435 is provided at an upper end 431 of the second cylindrical body 43. The lower end 412 of the coil spring 41 contacts the first flange 425 of the first cylindrical body 42, and the upper end 411 of the coil spring 41 contacts the second flange 435 of the second cylindrical body 43.

[0051] In this case, the first flange 425 and the second flange 435 are subjected to the elastic repulsive force of the coil spring 41. Therefore, the coil spring 41 presses the first flange 425 toward the axle box 30, and presses the second flange 435 toward the side beam 11. Due to this elastic repulsive force of the coil spring 41, the first cylindrical body 42 is pressed against the axle box 30 and fixed to the axle box 30, and the second cylindrical body 43 is pressed against the side beam 11 and fixed to the side beam 11.

[0052] Each of the plurality of permanent magnets 44 typically has an annular shape. The permanent magnets 44 are arranged substantially coaxially with the coil spring 41. The permanent magnets 44 are held on the circumferential surface of the first cylindrical body 42 that faces the second cylindrical body 43, either the inner circumferential surface 423 or the outer circumferential surface 424. In this embodiment, the permanent magnets 44 are held on the outer circumferential surface 424 of the first cylindrical body 42. These permanent magnets 44 are arranged at equal intervals in the axial direction of the coil spring 41. That is, the plurality of permanent magnets 44 are arranged in multiple stages in the vertical direction.

[0053] The magnetic poles (north and south poles) of each permanent magnet 44 are aligned in the radial direction. That is, the radial direction is the magnetization direction of each permanent magnet 44. The permanent magnets 44 are provided on the first cylindrical body 42 so that the magnetic poles of adjacent permanent magnets 44 in the axial direction are reversed. Specifically, if the north pole of a certain permanent magnet 44 is positioned on the radial outside and the south pole on the radial inside, the permanent magnets 44 on both sides of this permanent magnet 44 will have their south poles positioned on the radial outside and their north poles positioned on the radial inside. In FIG. 2, the magnetization direction is represented by arrows, with the start point of the arrow representing the south pole and the end point of the arrow representing the north pole.

[0054] Each permanent magnet 44 is composed of a single magnet. Each permanent magnet 44 may be divided in the circumferential direction. That is, each permanent magnet 44 may be composed of arc-shaped small magnets arranged in the circumferential direction. The permanent magnets 44 may be magnetized before or after being attached to the first cylindrical body 42.

[0055] The conductive film 45 is provided on the inner circumferential surface 433 or the outer circumferential surface 434 of the second cylindrical body 43, the circumferential surface facing the first cylindrical body 42, facing the permanent magnet 44. Therefore, the conductive film 45 has a cylindrical shape. The conductive film 45 is disposed substantially coaxially with the coil spring 41. That is, the central axis of the conductive film 45 substantially coincides with the central axis X of the coil spring 41. In this embodiment, the conductive film 45 is provided on the inner circumferential surface 433 of the second cylindrical body 43. In this case, the outer circumferential surface 451 of the conductive film 45 and the inner circumferential surface 433 of the second cylindrical body 43 form the interface between the conductive film 45 and the second cylindrical body 43. The conductive film 45 may be provided over the entire axial area of ​​the inner circumferential surface 433 of the second cylindrical body 43, or may be provided over a portion of the inner circumferential surface 433 of the second cylindrical body 43 in the axial direction.

[0056] The conductive film 45 is made of a highly conductive material, such as copper, a copper alloy, aluminum, or an aluminum alloy. The conductive film 45 can be formed by, for example, plating, build-up welding, welding of a copper plate, or using a copper-steel clad material.

[0057] The link 46 extends in the fore-and-aft direction of the bogie. The link 46 connects the side beam 11 of the bogie frame 10 and the axle box 30. Rubber bushings 47 are provided on both ends of the link 46. The link 46 and the rubber bushings 47 support the fore-and-aft load acting between the bogie frame 10 and the axle box 30 with appropriate rigidity.

[0058] [Operation of the Axle Box Suspension Device] When a railway vehicle travels, the axle box 30 vibrates together with the wheelset 20F, 20R. When the axle box 30 vibrates vertically relative to the bogie frame 10, the first cylindrical body 42 fixed to the axle box 30 is displaced vertically relative to the second cylindrical body 43 fixed to the side beam 11 of the bogie frame 10. As a result, the permanent magnet 44 provided on the outer peripheral surface 424 of the first cylindrical body 42 is displaced vertically relative to the conductive film 45 provided on the inner peripheral surface 433 of the second cylindrical body 43, generating eddy currents in the conductive film 45. In other words, the conductive film 45 provided on the inner peripheral surface 433 of the second cylindrical body 43 serves as an eddy current generator. The eddy current generated in the conductive film 45 (eddy current generator) interacts with the magnetic field generated by the permanent magnet 44, generating a resistance force (Lorentz force) in the direction opposite to the direction of displacement of the first cylindrical body 42 relative to the second cylindrical body 43. This resistance force prevents the first cylindrical body 42 from being displaced in the up and down direction relative to the second cylindrical body 43. As a result, the vibration of the bogie frame 10 in the up and down direction relative to the axle box 30 is damped.

[0059] [Effect] In the axle box support device 40 according to this embodiment, the second cylindrical body 43, located outside the first cylindrical body 42, is fixed to the side beam 11. Therefore, the lower end 432 of the second cylindrical body 43, which is the outer cylindrical body, is open. In this case, when the railway vehicle is traveling, traveling wind is introduced from the lower end 432 of the second cylindrical body 43 into the space S between the inner circumferential surface 433 of the second cylindrical body 43, which is the outer cylindrical body, and the outer circumferential surface 424 of the first cylindrical body 42, which is the inner cylindrical body. The introduced traveling wind can effectively cool the conductive film 45 (eddy current generating portion) provided on the inner circumferential surface 433 of the second cylindrical body 43, and can also effectively cool the permanent magnets 44 held on the outer circumferential surface 424 of the first cylindrical body 42. Therefore, the axle box support device 40 according to this embodiment can ensure cooling performance for the eddy current generating portion.

[0060] In this embodiment, the outer peripheral surface 434 of the second cylindrical body 43 is in close contact with the spring cap 111 of the side ray 11. Furthermore, the conductive film 45, which is an eddy current generating portion, is in contact with the second cylindrical body 43. That is, the conductive film 45 is continuous with the second cylindrical body 43 and the spring cap 111, which have a large heat capacity. Therefore, heat generated in the conductive film 45 is thermally conducted to the second cylindrical body 43 and the spring cap 111 and dissipated. This further improves the cooling performance for the eddy current generating portion. However, the outer peripheral surface 434 of the second cylindrical body 43 may be separated from the spring cap 111 of the side ray 11.

[0061] In this embodiment, as described above, the elastic repulsive force of the coil spring 41 presses the first cylindrical body 42 against the axle box 30 via the first flange 425 and is fixed to the axle box 30, and the second cylindrical body 43 presses the second cylindrical body 43 against the side beam 11 via the second flange 435 and is fixed to the side beam 11. Therefore, no mechanical joining by, for example, welding is required to fix the first cylindrical body 42 to the axle box 30 and the second cylindrical body 43 to the side beam 11. This allows the axle box support device 40 to be assembled efficiently.

[0062] In this embodiment, the first cylindrical body 42 that holds the multiple permanent magnets 44 is disposed radially outward of the coil spring 41. Therefore, compared to the configuration of Patent Document 3, the circumferential length of the first cylindrical body 42 can be increased, and more permanent magnets 44 can be provided on the outer peripheral surface 424 of the first cylindrical body 42. Therefore, with the axle box support device 40 according to this embodiment, it is possible to increase the magnetic flux guided to the conductive film 45 and increase the damping force.

[0063] [Modification of the First Embodiment] FIG. 3 is a cross-sectional view showing the schematic configuration of a modification of the axle box support device 40 according to the first embodiment. Referring to FIG. 3, the side plate portion 111b of the spring cap 111 constitutes the second cylindrical body 43. In this case, when the railway vehicle is traveling, the wind directly hits the outer peripheral surface 434 of the second cylindrical body 43. This promotes cooling of the second cylindrical body 43 itself, which is provided with the conductive film 45, thereby enabling more effective cooling of the conductive film 45. Furthermore, because the side plate portion 111b of the spring cap 111 constitutes the second cylindrical body 43, there is no need to prepare the second cylindrical body 43 as a separate body, thereby reducing the number of parts. Furthermore, the reduced number of parts reduces component costs and simplifies assembly. Furthermore, the space S is expanded by the amount corresponding to the absence of the separate second cylindrical body 43. This allows, for example, the size of the permanent magnet 44 to be increased to improve damping force.

[0064] 4 is a cross-sectional view showing a schematic configuration of an axle box support device 40A according to a second embodiment. The axle box support device 40A according to this embodiment differs from the axle box support device 40 according to the first embodiment in the configurations of the first cylindrical body 42A, the second cylindrical body 43A, the permanent magnet 44A, and the conductive film 45A.

[0065] 4, the first cylindrical body 42A is disposed outside the second cylindrical body 43A. In other words, the second cylindrical body 43A is disposed inside the first cylindrical body 42A. Therefore, in this embodiment, the first cylindrical body 42A is an outer cylindrical body, and the second cylindrical body 43A is an inner cylindrical body. Therefore, the inner circumferential surface 423 of the first cylindrical body 42A faces the outer circumferential surface 434 of the second cylindrical body 43A.

[0066] The first cylindrical body 42A is fixed to the side beam 11. Specifically, the upper end portion 421 and the first flange 425A of the first cylindrical body 42A are fixed in contact with the lower surface of the base portion 111a of the spring cap 111 of the side beam 11. In the first cylindrical body 42A, the first flange 425A protrudes radially inward from the upper end portion 421 of the first cylindrical body 42A. In this embodiment, the outer peripheral surface 424 of the first cylindrical body 42A is in close contact with the side plate portion 111b of the spring cap 111 of the side beam 11. However, the outer peripheral surface 424 of the first cylindrical body 42A may be spaced apart from the spring cap 111 of the side beam 11.

[0067] The second cylindrical body 43A is fixed to the axle box 30. Specifically, the lower end portion 432 and the second flange 435A of the second cylindrical body 43A are fixed in contact with the upper surface of the axle box 30. In the second cylindrical body 43A, the second flange 435A protrudes radially inward from the lower end portion 432 of the second cylindrical body 43A.

[0068] The coil spring 41 is interposed between a first flange 425A and a second flange 435A. In this embodiment, the first flange 425A is provided at an upper end 421 of the first cylindrical body 42A, and the second flange 435A is provided at a lower end 432 of the second cylindrical body 43A. The upper end 411 of the coil spring 41 contacts the first flange 425A of the first cylindrical body 42A, and the lower end 412 of the coil spring 41 contacts the second flange 435A of the second cylindrical body 43A.

[0069] In this case, the first flange 425A and the second flange 435A are subjected to the elastic repulsive force of the coil spring 41. Therefore, the coil spring 41 presses the first flange 425A toward the side beam 11, and presses the second flange 435A toward the axle box 30. Due to this elastic repulsive force of the coil spring 41, the first cylindrical body 42A is pressed against the side beam 11 and fixed to the side beam 11, and the second cylindrical body 43A is pressed against the axle box 30 and fixed to the axle box 30.

[0070] The multiple permanent magnets 44A are held on the inner circumferential surface 423 of the first cylindrical body 42A. Meanwhile, the conductive film 45A is provided on the outer circumferential surface 434 of the second cylindrical body 43A. In this case, the inner circumferential surface 452 of the conductive film 45A and the outer circumferential surface 434 of the second cylindrical body 43A form the interface between the conductive film 45A and the second cylindrical body 43A. The conductive film 45A may be provided over the entire axial area of ​​the outer circumferential surface 434 of the second cylindrical body 43A, or may be provided over a portion of the outer circumferential surface 434 of the second cylindrical body 43A in the axial direction.

[0071] In the axle box support device 40A according to this embodiment, when the axle box 30 vibrates vertically relative to the bogie frame 10, the second cylindrical body 43A fixed to the axle box 30 is displaced vertically relative to the first cylindrical body 42A fixed to the side beam 11 of the bogie frame 10. As a result, the permanent magnet 44A provided on the inner peripheral surface 423 of the first cylindrical body 42A is displaced vertically relative to the conductive film 45A provided on the outer peripheral surface 434 of the second cylindrical body 43A, generating an eddy current in the conductive film 45A. In other words, the conductive film 45A provided on the outer peripheral surface 434 of the second cylindrical body 43A serves as an eddy current generator. The eddy current generated in the conductive film 45A (eddy current generator) interacts with the magnetic field generated by the permanent magnet 44A, generating a resistance force (Lorentz force) in the direction opposite to the direction of displacement of the first cylindrical body 42A relative to the second cylindrical body 43A. This resistance force prevents the first cylindrical body 42A from being displaced in the up and down direction relative to the second cylindrical body 43A, thereby damping the up and down vibration of the bogie frame 10 relative to the axle box 30.

[0072] In the axle box support device 40A according to this embodiment, the first cylindrical body 42A, located outside the second cylindrical body 43A, is fixed to the side beam 11. Therefore, the lower end 422 of the first cylindrical body 42A, which is the outer cylindrical body, is open. In this case, when the railway vehicle is traveling, wind generated by the traveling is introduced from the lower end 422 of the first cylindrical body 42A into the space S between the inner circumferential surface 423 of the first cylindrical body 42A, which is the outer cylindrical body, and the outer circumferential surface 434 of the second cylindrical body 43A, which is the inner cylindrical body. The introduced wind can effectively cool the conductive film 45A (eddy current generating portion) provided on the outer circumferential surface 434 of the second cylindrical body 43A, and can also effectively cool the permanent magnet 44A held on the inner circumferential surface 423 of the first cylindrical body 42A. Therefore, the axle box support device 40A according to this embodiment ensures sufficient cooling performance for the eddy current generating portion.

[0073] In this embodiment, the conductive film 45A is held on the outer peripheral surface 434 of the second cylindrical body 43A. That is, the conductive film 45A is disposed in a position where it is likely to be directly hit by the traveling wind introduced into the space S between the inner peripheral surface 423 of the first cylindrical body 42A and the outer peripheral surface 434 of the second cylindrical body 43A. Therefore, the axle box support 40A according to the second embodiment can enhance the cooling effect of the traveling wind introduced into the space S compared to the axle box support 40 according to the first embodiment.

[0074] In this embodiment, the second cylindrical body 43A is fixed to the axle box 30. The conductive film 45A, which is an eddy current generating portion, is in contact with the second cylindrical body 43A. That is, the conductive film 45A is continuous with the second cylindrical body 43A, which has a large heat capacity, and the axle box 30. Therefore, heat generated in the conductive film 45A is conducted to the second cylindrical body 43A and the axle box 30 and dissipated. This further improves the cooling performance for the eddy current generating portion.

[0075] In the axle box support 40A according to this embodiment, the first cylindrical body 42A is pressed against the side beam 11 via the first flange 425A and fixed to the side beam 11 by the elastic repulsive force of the coil spring 41, and the second cylindrical body 43A is pressed against the axle box 30 via the second flange 435A and fixed to the axle box 30. Therefore, mechanical joining by, for example, welding is not required to fix the first cylindrical body 42A to the side beam 11 and the second cylindrical body 43A to the axle box 30. This allows the axle box support 40A to be assembled efficiently.

[0076] [Modification of the Second Embodiment] FIG. 5 is a cross-sectional view showing the schematic configuration of a modification of the axle box support device 40A according to the second embodiment. Referring to FIG. 5, the side plate portion 111b of the spring cap 111 constitutes the first cylindrical body 42A. In this case, when the railway vehicle is traveling, the wind directly hits the outer peripheral surface 424 of the first cylindrical body 42A. This promotes cooling of the first cylindrical body 42A, on which the permanent magnet 44A is mounted, thereby enabling more effective cooling of the permanent magnet 44A. Furthermore, since there is no need to prepare the first cylindrical body 42A as a separate body, the number of parts can be reduced. Furthermore, the reduced number of parts reduces component costs and simplifies assembly. Furthermore, the space S is expanded by the absence of the separate first cylindrical body 42A. This allows, for example, the size of the permanent magnet 44A to be increased to improve damping force.

[0077] <Third embodiment> Figure 6 is a cross-sectional view showing the schematic configuration of an axle box support 40B according to the third embodiment. The axle box support 40B according to this embodiment differs from the axle box support 40, 40A according to the first and second embodiments in that the installation position of the axle box support 40B is not limited to the position of the end of the side beam 11. Furthermore, the axle box support 40B differs from the axle box support 40A according to the second embodiment in the configuration of the first cylindrical body 42B and the second cylindrical body 43B.

[0078] 6, the first cylindrical body 42B is disposed outside the second cylindrical body 43B, similar to the first cylindrical body 42A of the second embodiment. In other words, the second cylindrical body 43B is disposed inside the first cylindrical body 42B. Therefore, in this embodiment, the first cylindrical body 42B is an outer cylindrical body, and the second cylindrical body 43B is an inner cylindrical body. Therefore, the inner circumferential surface 423 of the first cylindrical body 42B faces the outer circumferential surface 434 of the second cylindrical body 43B. The permanent magnet 44A is held on the inner circumferential surface 423 of the first cylindrical body 42B, and the conductive film 45A is provided on the outer circumferential surface 434 of the second cylindrical body 43B.

[0079] However, unlike the first cylindrical body 42A of the second embodiment, the first cylindrical body 42B is fixed to the axle box 30. That is, like the first cylindrical body 42 of the first embodiment, the first cylindrical body 42B is fixed to the axle box 30. Specifically, the lower end portion 422 and the first flange 425 of the first cylindrical body 42B are fixed in contact with the upper surface of the axle box 30.

[0080] Unlike the second cylindrical body 43A of the second embodiment, the second cylindrical body 43B is fixed to the side beam 11. That is, similar to the second cylindrical body 43 of the first embodiment, the second cylindrical body 43B is fixed to the side beam 11. Specifically, the upper end portion 431 and the second flange 435 of the second cylindrical body 43B are fixed in contact with the lower surface of the side beam 11.

[0081] In the axle box suspension 40B according to this embodiment, similarly to the axle box suspension 40 according to the first embodiment, a first cylindrical body 42B that holds a permanent magnet 44A is fixed to the axle box 30, and a second cylindrical body 43B on which a conductive film 45A is provided is fixed to the side beam 11. Therefore, similarly to the axle box suspension 40 according to the first embodiment, the resistance force due to eddy currents generated in the conductive film 45A damps up-and-down vibration of the bogie frame 10 relative to the axle box 30.

[0082] In the axle box support device 40B according to this embodiment, the first cylindrical body 42B, located outside the second cylindrical body 43B, is fixed to the axle box 30. Therefore, the upper end 421 of the first cylindrical body 42B, which is the outer cylindrical body, is open. In this case, when the railway vehicle is traveling, traveling wind is introduced from the upper end 421 of the first cylindrical body 42B into the space S between the inner circumferential surface 423 of the first cylindrical body 42B, which is the outer cylindrical body, and the outer circumferential surface 434 of the second cylindrical body 43B, which is the inner cylindrical body. The introduced traveling wind can effectively cool the conductive film 45A (eddy current generating portion) provided on the outer circumferential surface 434 of the second cylindrical body 43B, and can also effectively cool the permanent magnet 44A held on the inner circumferential surface 423 of the first cylindrical body 42B. Therefore, the axle box support device 40B according to this embodiment can ensure cooling performance for the eddy current generating portion.

[0083] 7 is a cross-sectional view showing a schematic configuration of an axle box support 40C according to a fourth embodiment. The axle box support 40C according to this embodiment differs from the axle box support 40 according to the first embodiment in the configurations of the first cylindrical body 42C and the second cylindrical body 43C.

[0084] 7, the first cylindrical body 42C is disposed inside the second cylindrical body 43C, similar to the first cylindrical body 42 of the first embodiment. In other words, the second cylindrical body 43C is disposed outside the first cylindrical body 42C. Therefore, in this embodiment, the first cylindrical body 42C is an inner cylindrical body, and the second cylindrical body 43C is an outer cylindrical body. Therefore, the outer peripheral surface 424 of the first cylindrical body 42C faces the inner peripheral surface 433 of the second cylindrical body 43C. The permanent magnet 44 is held on the outer peripheral surface 424 of the first cylindrical body 42C, and the conductive film 45 is provided on the inner peripheral surface 433 of the second cylindrical body 43C.

[0085] However, unlike the first cylindrical body 42 of the first embodiment, the first cylindrical body 42C is fixed to the side beam 11. That is, like the first cylindrical body 42A of the second embodiment, the first cylindrical body 42C is fixed to the side beam 11. Specifically, the upper end portion 421 and the first flange 425A of the first cylindrical body 42C are fixed in contact with the lower surface of the side beam 11.

[0086] Unlike the second cylindrical body 43 of the first embodiment, the second cylindrical body 43C is fixed to the axle box 30. That is, similar to the second cylindrical body 43A of the second embodiment, the second cylindrical body 43C is fixed to the axle box 30. Specifically, the lower end portion 432 and the second flange 435A of the second cylindrical body 43C are fixed in contact with the upper surface of the axle box 30.

[0087] In the axle box suspension 40C according to this embodiment, similarly to the axle box suspension 40A according to the second embodiment, a first cylindrical body 42C that holds a permanent magnet 44 is fixed to the side beam 11, and a second cylindrical body 43C provided with a conductive film 45 is fixed to the axle box 30. Therefore, similarly to the axle box suspension 40A according to the second embodiment, the resistance force of eddy currents generated in the conductive film 45 damps up-and-down vibration of the bogie frame 10 relative to the axle box 30.

[0088] In the axle box support device 40C according to this embodiment, the second cylindrical body 43C, located outside the first cylindrical body 42C, is fixed to the axle box 30. Therefore, the upper end 431 of the second cylindrical body 43C, which is the outer cylindrical body, is open. In this case, when the railway vehicle is traveling, traveling wind is introduced from the upper end 431 of the second cylindrical body 43C into the space S between the outer peripheral surface 424 of the first cylindrical body 42C, which is the inner cylindrical body, and the inner peripheral surface 433 of the second cylindrical body 43C, which is the outer cylindrical body. The introduced traveling wind can effectively cool the conductive film 45 (eddy current generating portion) provided on the inner peripheral surface 433 of the second cylindrical body 43C and can also effectively cool the permanent magnet 44 held on the outer peripheral surface 424 of the first cylindrical body 42C. Therefore, the axle box support device 40C according to this embodiment can ensure cooling performance for the eddy current generating portion.

[0089] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0090] In the above embodiment, the multiple permanent magnets 44, 44A are arranged in the axial direction in an N-S array, with the magnetization directions alternately reversed in the radial direction. However, the multiple permanent magnets 44, 44A may also be arranged in the axial direction in a Halbach array. Figure 8 shows an example in which the multiple permanent magnets 44 are arranged in a Halbach array. Figure 8 is an enlarged view of a portion of the axle box support device 40 according to the first embodiment shown in Figure 2. In Figure 8, the magnetization directions are represented by arrows, with the start point of the arrow representing the south pole and the end point of the arrow representing the north pole.

[0091] 8, the permanent magnets 44 are provided on the first cylindrical body 42 so that the magnetization directions of adjacent permanent magnets 44 in the axial direction are rotated by 90°. In other words, permanent magnets 44 with radial magnetization directions and permanent magnets 44 with axial magnetization directions are arranged alternately in the axial direction. Specifically, if a certain permanent magnet 44 has a magnetization direction facing radially outward, the permanent magnets 44 on both sides of this permanent magnet 44 have magnetization directions facing toward the permanent magnet 44 with a radially outward magnetization direction. Furthermore, if a certain permanent magnet 44 has a magnetization direction facing radially inward, the permanent magnets 44 on both sides of this permanent magnet 44 have magnetization directions facing opposite to the permanent magnets 44 with a radially inward magnetization direction.

[0092] By employing such a Halbach array, the concentration of magnetic flux guided from the permanent magnet 44 to the conductive film 45 is increased. As a result, a higher damping force is obtained. In the example of FIG. 8 , the rotation angle of the magnetization direction of the permanent magnet 44 may be other than 90° as long as it is possible to increase the magnetic flux density from the permanent magnet 44 to the conductive film 45.

[0093] The first and second cylindrical bodies only need to have opposing surfaces to accommodate the permanent magnets and conductive films. For example, the first and second cylindrical bodies do not need to be perfectly cylindrical. Specifically, the first and second cylindrical bodies may have a C-shape with a circumferentially interrupted portion when viewed from above. In this case, the permanent magnet held by the first cylindrical body and the conductive film provided on the second cylindrical body also do not need to be perfectly cylindrical. With this configuration, outside air flows in and out through the C-shaped opening, thereby further improving the cooling performance for the eddy current generating section.

[0094] The side plate portion of the spring cap preferably has a completely cylindrical shape, but does not have to have a completely cylindrical shape. Specifically, the side plate portion may have a C-shape with a circumferentially interrupted portion when viewed from above. Furthermore, when the side plate portion is separate from the first cylindrical body and the second cylindrical body, the side plate portion does not have to have a cylindrical shape and may have, for example, a rectangular cylindrical shape.

[0095] The method of fixing the first cylindrical body and the second cylindrical body to the side beams and axle boxes of the bogie frame is not limited to the method using the elastic repulsive force of the coil springs. The fixing method may be joining by welding, bolting, or the like. When the fixing method is welding, the first cylindrical body may not include the first flange, and the second cylindrical body may not include the second flange.

[0096] 10: Bogie frame 11: Side beam 30: Axle box 40, 40A, 40B, 40C: Axle box support device 41: Coil spring 42, 42A, 42B, 42C: First cylindrical body 43, 43A, 43B, 43C: Second cylindrical body 44, 44A: Permanent magnet 45, 45A: Conductive film 100: Bogie 111: Spring cap 111b: Side plate portion 411: Upper end portion 412: Lower end portion 421: Upper end portion 422: Lower end portion 423: Inner peripheral surface 424: Outer peripheral surface 425, 425A: First flange 431: Upper end portion 432: Lower end portion 433: Inner peripheral surface 434: Outer peripheral surface 435, 435A: Second flange

Claims

1. An axle box support device that holds an axle box on a bogie frame, comprising: a coil spring arranged on the axle box to support a side beam of the bogie frame; a magnetic first cylindrical body that is arranged coaxially with and outside the coil spring, and is fixed to one of the side beam and the axle box; a magnetic second cylindrical body that is arranged coaxially with the coil spring outside the coil spring and inside or outside the first cylindrical body, and is fixed to the other of the side beam and the axle box; a plurality of permanent magnets held on the inner and outer surfaces of the first cylindrical body that faces the second cylindrical body and are arranged along the axial direction of the first cylindrical body; and a conductive film provided on the inner and outer surfaces of the second cylindrical body that faces the first cylindrical body, facing the permanent magnets.

2. An axle box support device as claimed in claim 1, wherein the first cylindrical body is fixed to the axle box, the second cylindrical body is arranged outside the first cylindrical body and fixed to the side beam, the plurality of permanent magnets are held on the outer peripheral surface of the first cylindrical body, and the conductive film is provided on the inner peripheral surface of the second cylindrical body.

3. An axle box support device as claimed in claim 2, wherein a spring cap including a cylindrical side plate portion arranged coaxially with the coil spring is provided at the longitudinal end of the side beam, and the side plate portion of the spring cap constitutes the second cylindrical body.

4. An axle box support device as claimed in claim 1, wherein the first cylindrical body is fixed to the side beam, the second cylindrical body is arranged inside the first cylindrical body and fixed to the axle box, the plurality of permanent magnets are held on the inner peripheral surface of the first cylindrical body, and the conductive film is provided on the outer peripheral surface of the second cylindrical body.

5. An axle box support as claimed in claim 4, wherein a spring cap including a cylindrical side plate portion arranged coaxially with the coil spring is provided at the longitudinal end of the side beam, and the side plate portion of the spring cap constitutes the first cylindrical body.

6. An axle box support device as claimed in claim 1, wherein the first cylindrical body is fixed to the axle box, the second cylindrical body is arranged inside the first cylindrical body and fixed to the side beam, the plurality of permanent magnets are held on the inner peripheral surface of the first cylindrical body, and the conductive film is provided on the outer peripheral surface of the second cylindrical body.

7. An axle box support device as claimed in claim 1, wherein the first cylindrical body is fixed to the side beam, the second cylindrical body is arranged outside the first cylindrical body and fixed to the axle box, the plurality of permanent magnets are held on the outer peripheral surface of the first cylindrical body, and the conductive film is provided on the inner peripheral surface of the second cylindrical body.

8. An axle box support device as claimed in claim 4 or 7, wherein the first cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side, and includes a first flange protruding radially inward from the upper end of the first cylindrical body, the second cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side, and includes a second flange protruding radially inward from the lower end of the second cylindrical body, and the coil spring is interposed between the first flange and the second flange.

9. An axle box support device as claimed in claim 2 or 6, wherein the first cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side, and includes a first flange protruding radially inward from the lower end of the first cylindrical body, the second cylindrical body has an upper end located on the side beam side and a lower end located on the axle box side, and includes a second flange protruding radially inward from the upper end of the second cylindrical body, and the coil spring is interposed between the first flange and the second flange.

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