Railway vehicle wheels

Abstract

A wheel (100) comprises a boss part (10), a rim part (20), and a plate part (30). A rim width center (Cr) is located on a flange (22) side of the rim part (20) with respect to a boss width center (Cb). The plate part (30) has a linear plate-thickness center line (A) in a vertical cross-sectional view of the wheel (100). The plate-thickness center line (A) is inclined with respect to the radial direction of the wheel (100) so as to be farther from the flange (22) toward the outside in the radial direction. Letting Pw be the distance in the axial direction of the wheel (100) from a side surface (24) of the rim part (20) to an outer end (Aa) of the plate-thickness center line (A) and Wr be the length in the axial direction of the rim part (20), Pw / Wr is less than 0.40.

Description

[Technical Field]

[0001] The present disclosure relates to wheels for rail vehicles. [Background technology]

[0002] A wheel for a railway vehicle generally comprises a boss portion, a rim portion, and a plate portion. An axle is inserted into the boss portion. The rim portion forms the outer periphery of the wheel and includes a tread surface and a flange. The tread surface is the surface that contacts the top surface of the rail. The flange is connected to one end of the tread surface in the axial direction of the wheel and protrudes outward in the radial direction of the wheel relative to the tread surface. The plate portion connects the rim portion and the boss portion.

[0003] Conventionally, there are various shapes of railway vehicle wheels. For example, Patent Document 1 discloses a wheel with a curved plate portion. In Patent Document 1, the plate thickness centerline of the plate portion has a substantially S-shape in a longitudinal cross section of the wheel. The plate thickness centerline has an inflection point at its center and is symmetrical with respect to the inflection point.

[0004] Patent Documents 2 and 3 also disclose wheels with curved plate portions. In these documents, the plate thickness centerline of the plate portion has a shape that is convex on the opposite side of the flange in a longitudinal cross-sectional view of the wheel. The plate thickness centerline is a curve with both ends positioned on the flange side relative to the midpoint. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-29401 [Patent Document 2] Special Publication No. 2009-545484 [Patent Document 3] Special Publication No. 2015-500177 Summary of the Invention [Problem to be solved by the invention]

[0006] Tread brakes are known as one type of braking device for railway vehicles. Tread brakes brake a railway vehicle by pressing brake shoes against the wheel tread. During braking, frictional heat is generated between the tread and the brake shoes. This causes the temperature of the rim, including the tread, to rise, resulting in thermal deformation of the rim. Thermal deformation and displacement of the rim affect the running stability of the railway vehicle. In particular, axial displacement of the rim may lead to meandering or derailment of the railway vehicle. Furthermore, thermal deformation of the rim during braking may cause thermal stress in the plate, potentially resulting in fatigue failure of the wheel. Therefore, during braking of a railway vehicle using tread brakes, it is necessary to reduce the axial displacement of the rim and the thermal stress in the plate. However, with conventional wheels such as those described in Patent Documents 1 to 3, it is difficult to simultaneously reduce both the rim displacement and the thermal stress in the plate during braking.

[0007] The present disclosure aims to provide a railway vehicle wheel that can simultaneously reduce the displacement of the rim portion in the axial direction of the wheel and the thermal stress generated in the plate portion during braking of the railway vehicle by a tread brake. [Means for solving the problem]

[0008] The wheel according to the present disclosure is a wheel for a railway vehicle. The wheel includes a boss portion, a rim portion, and a plate portion. The boss portion forms the inner peripheral portion of the wheel. An axle of the railway vehicle is inserted into the boss portion. The rim portion forms the outer peripheral portion of the wheel. The rim portion includes a tread surface and a flange. The tread surface contacts the head surface of the rail on which the railway vehicle runs. The flange is connected to one end of the tread surface in the axial direction of the wheel and protrudes outward from the tread surface in the radial direction of the wheel. The center of the rim portion in the axial direction of the wheel is located on the flange side relative to the center of the boss portion in the axial direction. The plate portion connects the boss portion and the rim portion. The plate portion has an annular shape. The thickness centerline of the plate portion is linear in a cross section of the wheel that includes the central axis. The thickness centerline is inclined relative to the radial direction of the wheel so as to move away from the flange as it moves outward in the radial direction of the wheel. When the distance in the axial direction of the wheel from the side surface of the rim portion to the outer end of the thickness centerline is Pw and the length of the rim portion in the axial direction is Wr, Pw / Wr is less than 0.40. The side surface of the rim portion is the side farthest from the flange of both side surfaces of the rim portion in the axial direction of the wheel. The outer end of the thickness centerline is the end located radially outward of the two ends of the thickness centerline. [Effects of the Invention]

[0009] According to the railway vehicle wheel of the present disclosure, it is possible to simultaneously reduce displacement of the rim portion in the axial direction of the wheel and thermal stress occurring in the plate portion during braking of the railway vehicle by the tread brake. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view of a railway vehicle wheel according to an embodiment. [Figure 2A] FIG. 2A is a diagram showing the wheel shape used in the numerical analysis. [Figure 2B] FIG. 2B shows the wheel shape used in the numerical analysis. [Figure 2C] FIG. 2C shows the wheel shape used in the numerical analysis. [Figure 3]FIG. 3 is a diagram showing a wheel shape used in the numerical analysis as a reference example. [Figure 4] FIG. 4 is a diagram showing the relationship between the plate angle θ and the amount of displacement of the rim when the plate position Pw / rim width Wr and the rim root R are constant. [Figure 5] FIG. 5 is a diagram showing the relationship between the plate position Pw / rim width Wr and the amount of displacement of the rim when the plate angle θ and the rim root R are constant. [Figure 6] FIG. 6 is a diagram showing the relationship between the rim root R and the amount of displacement of the rim portion when the plate portion position Pw / rim width Wr and the plate portion angle θ are constant. [Figure 7] FIG. 7 is a diagram showing the relationship between the plate angle θ and the plate thermal stress when the plate position Pw / rim width Wr and the rim root R are constant. [Figure 8] FIG. 8 is a diagram showing the relationship between the plate position Pw / rim width Wr and the plate thermal stress when the plate angle θ and the rim root R are constant. [Figure 9] FIG. 9 is a diagram showing the relationship between the rim root R and the plate thermal stress when the plate position Pw / rim width Wr and the plate angle θ are constant. DETAILED DESCRIPTION OF THE INVENTION

[0011] The wheel according to the embodiment is a wheel for a railway vehicle. The wheel includes a boss portion, a rim portion, and a plate portion. The boss portion forms the inner peripheral portion of the wheel. An axle of the railway vehicle is inserted into the boss portion. The rim portion forms the outer peripheral portion of the wheel. The rim portion includes a tread surface and a flange. The tread surface contacts the head surface of the rail on which the railway vehicle runs. The flange is connected to one end of the tread surface in the axial direction of the wheel and protrudes outward from the tread surface in the radial direction of the wheel. The center of the rim portion in the axial direction of the wheel is located on the flange side relative to the center of the boss portion in the axial direction. The plate portion connects the boss portion and the rim portion. The plate portion has an annular shape. The thickness centerline of the plate portion is linear in a cross section of the wheel that includes the central axis. The thickness centerline is inclined relative to the radial direction of the wheel so as to move away from the flange as it moves outward in the radial direction of the wheel. When the distance from the side surface of the rim portion to the outer end of the thickness centerline in the axial direction of the wheel is Pw and the length of the rim portion in the axial direction is Wr, Pw / Wr is less than 0.40. The side surface of the rim portion is the side surface farthest from the flange of both side surfaces of the rim portion in the axial direction of the wheel. The outer end of the thickness centerline is the end of both ends of the thickness centerline that is located radially outward of the wheel (first configuration).

[0012] When the brake shoe of the tread brake is pressed against the wheel tread, generating frictional heat, the rim portion thermally deforms and displaces in the axial direction of the wheel. In contrast, in a wheel with a first configuration, the center of the rim portion is located closer to the flange than the center of the boss portion, and the linear thickness center line of the plate portion is inclined relative to the radial direction so as to move away from the flange as it moves radially outward. This reduces displacement of the rim portion in the axial direction of the wheel during braking of the railway vehicle by the tread brake. Furthermore, because the thickness center line does not have an inflection point, stress concentration is less likely to occur in the plate portion. This reduces thermal stress occurring in the plate portion during braking of the railway vehicle by the tread brake.

[0013] Furthermore, in the first configuration, the distance from the side of the rim portion opposite the flange to the outer edge of the plate portion's thickness centerline is somewhat reduced. More specifically, the ratio of this distance Pw to the overall width Wr of the rim portion is less than 0.40. This further reduces the displacement of the rim portion in the axial direction of the wheel and the thermal stress generated in the plate portion during braking of the railway vehicle.

[0014] In the wheel according to the first configuration, Pw / Wr may be 0.30 or more (second configuration).

[0015] In the wheel according to the first or second configuration, the angle that the plate thickness centerline makes with the axial direction on the side opposite the flange is preferably 89° or less (third configuration). The angle is, for example, 85° or more (fourth configuration).

[0016] In the wheel according to any one of the first to fourth configurations, the flange-side surface of the plate portion may be connected to the surface of the rim portion via a connecting portion that has an arc-shaped cross section including the center axis of the wheel. The radius of curvature of the connecting portion is preferably 20 mm or more (fifth configuration).

[0017] In the wheel according to any one of the first to fifth configurations, the plate portion may have a minimum thickness at a position radially inward relative to an outer end of the plate thickness centerline. The plate thickness of the plate portion may decrease radially outward until it reaches the position of minimum thickness (sixth configuration).

[0018] 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.

[0019] [Wheel configuration] FIG. 1 is a longitudinal cross-sectional view of a wheel 100 for a railway vehicle according to this embodiment. The longitudinal cross-section of the wheel 100 refers to a cross-section of the wheel 100 that includes a central axis X. Because the longitudinal cross-section of the wheel 100 is symmetrical with respect to the central axis X, FIG. 1 shows only one side of the wheel 100 about the central axis X. In this embodiment, the direction in which the central axis X of the wheel 100 extends is referred to as the axial direction, and the radial direction of the wheel 100 may simply be referred to as the radial direction.

[0020] Referring to FIG. 1, a wheel 100 includes a boss portion 10, a rim portion 20, and a plate portion 30.

[0021] The boss portion 10 forms the inner periphery of the wheel 100. The boss portion 10 has a substantially cylindrical shape with a central axis X as its axis. An axle (not shown) of a railway vehicle is inserted into the boss portion 10.

[0022] The rim portion 20 forms the outer periphery of the wheel 100. The rim portion 20 includes a tread surface 21 and a flange 22.

[0023] The tread surface 21 is the surface facing outward in the radial direction of the wheel 100. The tread surface 21 comes into contact with the top surface of the rail on which the railway vehicle runs. Although not particularly limited, the tread surface 21 may be, for example, a conical tread surface or an arcuate tread surface.

[0024] The flange 22 protrudes outward relative to the tread 21 in the radial direction of the wheel 100. When the railway vehicle runs on rails, the flange 22 is positioned on the inside of the left and right rails. The flange 22 is connected to one end of the tread 21 in the axial direction of the wheel 100. The flange 22 is also connected to one side surface 23 of both side surfaces 23, 24 in the axial direction of the rim portion 20. The tread 21 is connected to the other side surface 24 of the rim portion 20. Hereinafter, the direction toward the flange 22 along the axial direction will be referred to as the flange direction, and the direction opposite to the flange direction will be referred to as the anti-flange direction.

[0025] The rim portion 20 is positioned inward in the raceway width direction relative to the boss portion 10. More specifically, the rim width center Cr is positioned closer to the flange 22 than the boss width center Cb. The rim width center Cr is the center of the rim portion 20 in the axial direction. The boss width center Cb is the center of the boss portion 10 in the axial direction.

[0026] The plate portion 30 has an annular shape with the central axis X as its axis. The plate portion 30 connects the boss portion 10 and the rim portion 20. The thickness of the plate portion 30 as a whole is smaller than the axial lengths of the boss portion 10 and the rim portion 20.

[0027] The plate portion 30 includes side surfaces 31 and 32. The side surface 31 is the surface of the plate portion 30 on the flange 22 side. The side surface 32 is the surface of the plate portion 30 opposite the flange 22. The side surfaces 31 and 32 are connected to the surface of the rim portion 20 via connecting portions 41 and 42, respectively. The side surfaces 31 and 32 are connected to the surface of the boss portion 10 via connecting portions 43 and 44, respectively.

[0028] Each of the connecting portions 41, 42, 43, and 44 has a substantially arc shape in a vertical cross-sectional view of the wheel 100. The radius of curvature of the connecting portions 41, 42, 43, and 44 can be determined appropriately. For example, the radius of curvature of the connecting portion 41 connecting the side surface 31 of the plate portion 30 and the rim portion 20 is preferably 20 mm or more, and more preferably 40 mm or more.

[0029] In this embodiment, of the end (R-stop) 411 of the connecting portion 41 on the plate portion 30 side and the end (R-stop) 421 of the connecting portion 42 on the plate portion 30 side, the one positioned more inward in the radial direction is defined as the outer peripheral end of the plate portion 30. Also, of the end (R-stop) 431 of the connecting portion 43 on the plate portion 30 side and the end (R-stop) 441 of the connecting portion 44 on the plate portion 30 side, the one positioned more outward in the radial direction is defined as the inner peripheral end of the plate portion 30. In the example shown in FIG. 1 , the end 411 of the connecting portion 41 and the end 431 of the connecting portion 43 are the outer peripheral end and the inner peripheral end of the plate portion 30, respectively.

[0030] The plate portion 30 has a plate thickness centerline A. The plate thickness centerline A is an imaginary line passing through the center of the plate thickness of the plate portion 30 extending from the boss portion 10 to the rim portion 20 in a vertical cross-sectional view of the wheel 100. The plate thickness centerline A passes through the middle between the side surfaces 31, 32 of the plate portion 30, extending from the boss portion 10 side to the rim portion 20 side.

[0031] The plate thickness center line A has a straight line shape in a vertical cross-sectional view of the wheel 100. Here, the concept of a straight line does not only mean a perfect straight line, but also includes, for example, a very gentle arc with a curvature radius of 1000 mm or more, or a broken line. In other words, the plate thickness center line A may be any line that can be recognized as a substantially straight line in a vertical cross-sectional view of the wheel 100. Because the plate thickness center line A is straight in a vertical cross-sectional view of the wheel 100, the plate portion 30 has a substantially flat plate shape and is not curved in the flange direction or the anti-flange direction.

[0032] The thickness center line A has an outer end Aa and an inner end Ab. The outer end Aa is the end that is located radially outward of both end portions of the thickness center line A. The inner end Ab is the end that is located radially inward of both end portions of the thickness center line A. The outer end Aa is the point at which the thickness center line A is connected to an imaginary line that passes through the outer peripheral end 411 of the plate portion 30 and extends in the axial direction in a longitudinal cross-sectional view of the wheel 100. The inner end Ab of the thickness center line A is the point at which the thickness center line A is connected to an imaginary line that passes through the inner peripheral end 431 of the plate portion 30 and extends in the axial direction in a longitudinal cross-sectional view of the wheel 100.

[0033] The thickness center line A is inclined relative to the radial direction so as to move away from the flange 22 as it moves radially outward. The angle θ of the thickness center line A is less than 90°. The angle θ is preferably 89° or less. The angle θ may be 85° or more.

[0034] The angle θ is the angle that the thickness center line A makes with the axial direction on the opposite side of the flange 22. When the thickness center line A is a very gentle curve, the angle θ is the angle that the tangent at the center of the thickness center line A (the midpoint between the outer end Aa and the inner end Ab) makes with the axial direction. When the thickness center line A is a broken line, the angle θ is the angle that the longest line segment that makes up the thickness center line A makes with the axial direction. When the thickness center line A is parallel to the radial direction, the angle θ between the thickness center line A and the axial direction is 90°. When the outer end Aa of the thickness center line A is positioned in the anti-flange direction based on the position where the angle θ is 90°, the angle θ is less than 90°.

[0035] The outer end Aa of the plate thickness centerline A is positioned in the anti-flange direction relative to the rim width center Cr. When the axial length of the rim portion 20 is defined as the rim width Wr and the axial distance from the anti-flange side surface 24 of the rim portion 20 to the outer end Aa of the plate thickness centerline A is defined as the plate portion position Pw, Pw / Wr is less than 0.40. It is preferable that Pw / Wr is 0.30 or more.

[0036] The plate portion 30 has a minimum thickness at a position radially inward from the outer end Aa of the thickness centerline A. The plate portion 30 can have a minimum thickness near the outer end Aa of the thickness centerline A. The plate portion 30 can have a minimum thickness, for example, at a position 5 mm to 30 mm radially inward from the outer end Aa of the thickness centerline A. The thickness of the plate portion 30 gradually decreases radially outward until it reaches the position of minimum thickness. That is, the thickness of the plate portion 30 decreases radially outward and reaches a minimum just before the outer end Aa of the thickness centerline A. The position at which the plate portion 30 has a minimum thickness substantially coincides with the position at which the bending stress generated within the plate portion 30 due to the bending load that the wheel 100 receives from the rail when the railway vehicle travels on a curved section is minimum.

[0037] [effect] When a brake shoe of a tread brake is pressed against the tread 21 of the wheel 100 during braking of the railway vehicle, frictional heat between the tread 21 and the brake shoe causes thermal deformation of the rim portion 20, resulting in axial displacement. However, the wheel 100 according to this embodiment can reduce such displacement of the rim portion 20. That is, assuming that the rim width center Cr of the wheel 100 is positioned in the flange direction relative to the boss width center Cb, the linear thickness center line A of the plate portion 30 is inclined relative to the radial direction so as to move away from the flange 22 as it moves radially outward. This reduces displacement of the rim portion 20 in the axial direction of the wheel 100 during braking of the railway vehicle by the tread brake. Furthermore, because the thickness center line A is linear and has no inflection point, stress concentration is unlikely to occur in the plate portion 30. Therefore, thermal stress occurring in the plate portion 30 during braking of the railway vehicle by the tread brake can be reduced.

[0038] In the wheel 100 according to this embodiment, the plate portion position Pw is relatively small. That is, the ratio of the plate portion position Pw to the rim width Wr is less than 0.40, and the outer end Aa of the plate thickness centerline A is located relatively far from the flange 22. This makes it possible to further reduce the displacement of the rim portion 20 in the axial direction of the wheel 100 and the thermal stress generated in the plate portion 30 during braking of the railway vehicle by the tread brakes.

[0039] In the wheel 100 according to this embodiment, the ratio of the plate portion position Pw to the rim width Wr is preferably 0.30 or greater, which further reduces the thermal stress generated in the plate portion 30 during braking of the railway vehicle by the tread brake.

[0040] If the angle θ between the thickness center line A of the plate portion 30 and the axial direction of the wheel 100 is 90°, the bending moment acting on the wheel 100 becomes excessive when the railway vehicle passes through a curve, and stress concentration is likely to occur particularly at the base of the boss portion 10 of the plate portion 30. Therefore, if the angle θ of the thickness center line A is 90°, it is difficult to ensure the rigidity of the wheel 100 when passing through a curve. In contrast, in the wheel 100 according to this embodiment, the angle θ between the thickness center line A of the plate portion 30 and the axial direction is less than 90°. This makes it possible to ensure the rigidity of the wheel 100 when passing through a curve.

[0041] In the wheel 100 according to this embodiment, the angle θ of the plate thickness center line A is preferably 89° or less. This makes it possible to effectively reduce the displacement of the rim portion 20 in the axial direction of the wheel 100 and the thermal stress generated in the plate portion 30 while ensuring the rigidity of the wheel 100 when navigating a curve.

[0042] The angle θ of the plate thickness center line A is preferably equal to or greater than 85°, which makes it possible to more reliably reduce the thermal stress in the plate portion 30.

[0043] In the wheel 100 according to this embodiment, the side surface 31 of the plate portion 30 on the flange 22 side is connected to the surface of the rim portion 20 via a connecting portion 41. The radius of curvature of the connecting portion 41 is preferably 20 mm or more. This makes it possible to further reduce displacement of the rim portion 20 in the axial direction of the wheel 100 during braking of the railway vehicle by the tread brakes.

[0044] It is more preferable that the radius of curvature of the connection portion 41 is 40 mm or more, which can further reduce the displacement of the rim portion 20 as well as the thermal stress generated in the plate portion 30 during braking of the railway vehicle.

[0045] In this embodiment, the plate portion 30 has a minimum plate thickness radially inward of the outer end Aa of the plate thickness centerline A. Specifically, the position of the plate portion 30 where the bending stress caused by the bending load received from the rail when passing through a curve is minimum is substantially aligned with the position where the plate thickness is minimum. This prevents fatigue failure of the plate portion 30 and improves the lifespan of the wheel 100.

[0046] 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. [Example]

[0047] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to the following examples.

[0048] Numerical analysis using the finite element method (FEM analysis) was carried out to evaluate the effects of the railway vehicle wheel according to the present disclosure. In the FEM analysis, an analytical model having the shape of the wheel 100 (FIG. 1) according to the above embodiment was created, and evaluation was carried out by changing the angle (plate angle) θ of the plate thickness centerline A relative to the axial direction of the wheel 100, the plate position Pw / rim width Wr, and the rim root R (Nos. 1 to 17). The rim root R is the radius of curvature of the connection portion 41 that connects the side surface 31 of the plate portion 30 on the flange 22 side to the surface of the rim portion 20. For comparison, analytical models of wheel shapes commonly used in Europe and North America were also evaluated (Reference Examples 1 and 2).

[0049] 2A, 2B, and 2C are diagrams showing the wheel shapes (outlines in half cross sections) of Nos. 1 to 17. Fig. 3 is a diagram showing the wheel shapes (outlines in half cross sections) of Reference Examples 1 and 2. In each wheel shape, the rim width center Cr is positioned in the flange direction relative to the boss width center Cb.

[0050] 2A, 2B, and 2C, in the wheel shapes of Nos. 1 to 17, the plate thickness center line (dash line) of the plate portion is linear. However, in Nos. 1 to 15 shown in FIGS. 2A and 2B, the plate thickness center line is inclined with respect to the radial direction of the wheel, whereas in Nos. 16 and 17 shown in FIG. 2C, the plate thickness center line is parallel to the radial direction of the wheel. As shown in FIG. 3, in Reference Examples 1 and 2, unlike Nos. 1 to 17, the plate thickness center line of the plate portion is curved. Reference Example 1 is a wheel shape commonly used in Europe. Reference Example 2 is a wheel shape commonly used in North America.

[0051] The FEM analysis was performed using general-purpose software (ABAQUS Ver. 6.12, manufactured by Dassault Systèmes). In the analysis, to simulate the braking of a railway vehicle using a tread brake, a heat flux was applied to the area of ​​the wheel tread that comes into contact with the brake shoe of the tread brake. The braking time was set to 1200 seconds, and the inner circumference of the wheel was fully restrained. In the analysis, the axial displacement of the rim and the thermal stress in the plate (plate thermal stress) that occurred during braking of the railway vehicle were confirmed. The analysis results are shown in Table 1.

[0052] [Table 1]

[0053] The displacement in Table 1 is the maximum axial displacement of the rim portion during braking, with displacement toward the flange being negative and displacement toward the opposite flange being positive. The displacement of the rim portion was evaluated at a position 890 mm in diameter on the side of the rim portion on the flange side. The plate thermal stress is the maximum stress on the plate portion during braking. In Table 1, the plate thermal stress for Nos. 1 to 17 and each reference example is expressed as a ratio to the plate thermal stress of Reference Example 2.

[0054] [Axial displacement of rim] As shown in Table 1, in Nos. 1 to 17, in which the center line of the plate thickness of the plate portion is linear, the axial displacement of the rim portion during braking fell within the range (-1.0 mm to 3.0 mm) allowed by European standard EN13979-1.

[0055] The wheel shape of Reference Example 1 has two inflection points on the center line of the plate thickness of the plate part in order to suppress the displacement of the rim part. In Reference Example 1, the amount of axial displacement of the rim part during braking also fell within the range of the European standard.

[0056] On the other hand, the wheel shape of Reference Example 2 has a roughly S-shaped plate thickness centerline, which separates the base of the boss portion of the plate portion from the base of the rim portion in the axial direction, thereby reducing thermal stress in the plate portion. The wheel shape of Reference Example 2 was not designed with the displacement of the rim portion in mind. As a result, in Reference Example 2, the amount of axial displacement of the rim portion during braking fell outside the range specified in the European standard, and it was not possible to reduce the amount of axial displacement of the rim portion.

[0057] Figure 4 shows the relationship between plate angle θ and rim displacement when plate position Pw / rim width Wr and rim root R are constant. To show the effect of plate angle θ on rim displacement, Figure 4 plots the rim displacement corresponding to plate angle θ for tires Nos. 1, 6, and 14 to 16, where plate position Pw / rim width Wr is 0.37 and rim root R is 20 mm, and creates an approximate curve from these plots.

[0058] As shown in Figure 4, when the plate angle θ is changed from 85° to 90°, the larger the plate angle θ, the smaller the displacement of the rim. The displacement of the rim reaches its minimum when the plate angle θ = 90°. When the plate angle θ = 90°, the displacement of the rim falls within the range of the European standard, but it is difficult to ensure the rigidity of the wheel when the railway vehicle passes through a curve. Therefore, from the perspective of reducing the axial displacement of the rim while ensuring the rigidity of the wheel when passing through a curve, it is preferable that the plate angle θ is less than 90°. More preferably, the plate angle θ is 89° or less. Furthermore, based on the results of this analysis, the plate angle θ can be set to 85° or more.

[0059] Figure 5 is a diagram showing the relationship between plate position Pw / rim width Wr and rim displacement when plate angle θ and rim root R are constant. In order to show the effect of plate position Pw / rim width Wr on rim displacement, Figure 5 plots the rim displacement corresponding to plate position Pw / rim width Wr for Nos. 2 to 7 and 10, where the plate angle θ is 87° and the rim root R is 20 mm, and creates an approximate curve from these plots.

[0060] When the plate position Pw / rim width Wr is small to a certain extent, the axial displacement of the rim during braking can be suppressed. As shown in Figure 5, it was confirmed that the amount of rim displacement falls within the range of the European standard even when the plate position Pw / rim width Wr is changed from 0.19 to 0.47. In particular, when the plate position Pw / rim width Wr is less than 0.40, the amount of rim displacement is significantly reduced.

[0061] Figure 6 is a diagram showing the relationship between rim root R and rim displacement when the plate position Pw / rim width Wr and plate angle θ are constant. In order to show the effect of rim root R on rim displacement, Figure 6 plots the rim displacement corresponding to rim root R for Nos. 8 to 13, where the plate position Pw / rim width Wr is 0.47 and the plate angle θ is 87°, and an approximation curve is created from these plots.

[0062] As shown in Figure 6, even when the rim root R is changed from 5 mm to 50 mm, the amount of rim displacement remains within the range specified by the European Standard. However, when the rim root R is less than 20 mm, the amount of rim displacement is near the lower limit of the range specified by the European Standard. On the other hand, when the rim root R is 20 mm or more, the amount of rim displacement is near the median value of the range specified by the European Standard. Therefore, it is preferable that the rim root R is 20 mm or more.

[0063] [Plate thermal stress] As described above, the wheel shape of Reference Example 2 is a wheel shape for reducing the plate thermal stress. Therefore, in this analysis, the degree of reduction in the plate thermal stress was evaluated based on the plate thermal stress of Reference Example 2.

[0064] As shown in Table 1, in Nos. 1 to 17, the ratio of plate thermal stress to Reference Example 2 was less than 1.00, and the plate thermal stress was reduced. In Nos. 1 to 17, the axial displacement of the rim portion during braking of the railway vehicle could be reduced, and the plate thermal stress could also be reduced.

[0065] In Reference Example 1, the ratio of the plate thermal stress to that in Reference Example 2 exceeded 1.00, resulting in a large plate thermal stress. In the case of the wheel shape of Reference Example 1, the axial displacement of the rim was reduced during braking of the railway vehicle, but the plate thermal stress could not be reduced.

[0066] Figure 7 shows the relationship between the plate angle θ and plate thermal stress when the plate position Pw / rim width Wr and rim root R are constant. In order to show the effect of the plate angle θ on the plate thermal stress, Fig. 7 plots the plate thermal stress corresponding to the plate angle θ for Nos. 1, 6, and 14 to 16, where the plate position Pw / rim width Wr is 0.37 and the rim root R is 20 mm, and an approximate curve is created from these plots.

[0067] As shown in FIG. 7, when the plate angle θ is 85° or more, the plate thermal stress is reduced compared to Reference Example 2. The larger the plate angle θ, the smaller the plate thermal stress. The plate thermal stress is reduced most when the plate angle θ = 90°. However, as mentioned above, when the plate angle θ = 90°, it is difficult to ensure the rigidity of the wheels when the railway vehicle passes through a curve. From the viewpoint of reducing the plate thermal stress while ensuring the rigidity of the wheels when passing through a curve, it is preferable that the plate angle θ is less than 90°. More preferably, the plate angle θ is 89° or less.

[0068] Figure 8 shows the relationship between plate position Pw / rim width Wr and plate thermal stress when the plate angle θ and rim root R are constant. In order to confirm the effect of plate position Pw / rim width Wr on plate thermal stress, Fig. 8 plots plate thermal stress corresponding to plate position Pw / rim width Wr for Nos. 2 to 7, and 10, where the plate angle θ is 87° and the rim root R is 20 mm, and creates an approximate curve from these plots.

[0069] As shown in Figure 8, when the plate position Pw / rim width Wr is below 0.20, the plate thermal stress is nearly equal to that of Reference Example 2, and the plate thermal stress reduction effect is small. On the other hand, when the plate position Pw / rim width Wr is 0.30 or more, the plate thermal stress is significantly reduced compared to Reference Example 2. However, when the plate position Pw / rim width Wr is 0.40 or more, the plate thermal stress reduction effect becomes slightly smaller. Therefore, in order to reduce the plate thermal stress, it is preferable that the plate position Pw / rim width Wr be 0.30 or more and less than 0.40. However, when the plate position Pw / rim width Wr is small, the amount of displacement of the rim is small (Figure 5), so when considering both the displacement of the rim and the plate thermal stress, it is sufficient for the plate position Pw / rim width Wr to be less than 0.40.

[0070] Figure 9 shows the relationship between rim root R and plate thermal stress when the plate position Pw / rim width Wr and plate angle θ are constant. In order to show the effect of rim root R on plate thermal stress, Fig. 9 plots the plate thermal stress corresponding to rim root R for Nos. 8 to 13, where the plate position Pw / rim width Wr is 0.47 and the plate angle θ is 87°, and creates an approximate curve from these plots.

[0071] As shown in Figure 9, the plate thermal stress decreases as the rim root R increases. In particular, if the rim root R is 20 mm or more, the plate thermal stress is significantly reduced compared to Reference Example 2. If the rim root R is 40 mm or more, the plate thermal stress is further reduced. Therefore, from the perspective of reducing the plate thermal stress in addition to the axial displacement of the rim, it is preferable that the rim root R is 20 mm or more. In order to further reduce the plate thermal stress, it is preferable that the rim root R is 40 mm or more.

[0072] In a wheel according to the present disclosure, where the rim width center Cr is positioned in the flange direction relative to the boss width center Cb and the plate thickness centerline is inclined relative to the radial direction so as to point in the anti-flange direction from the inner periphery to the outer periphery of the wheel, it is possible to increase the flange-side rim root R. On the other hand, in a wheel where the rim width center Cr is positioned in the anti-flange direction relative to the boss width center Cb and the plate thickness centerline is inclined relative to the radial direction so as to point in the flange direction from the inner periphery to the outer periphery of the wheel, it is difficult to increase the flange-side rim root R to, for example, 40 mm or more. This is because, in such a wheel, if the flange-side rim root R is made too large, the degree of freedom in the plate inclination angle is significantly reduced. [Explanation of symbols]

[0073] 100: Wheels 10: Boss Section 20: Rim 21: Tread 22: Flange 23, 24: Side 30: Board part 41: Connection A: Thickness center line Aa: outer end

Claims

1. A wheel for a railway vehicle, a boss portion that forms an inner circumferential portion of the wheel and into which an axle of the railway vehicle is inserted; a rim portion including a tread surface that forms the outer periphery of the wheel and contacts the top surface of the rail on which the railway vehicle runs, and a flange that is connected to one end of the tread surface in the axial direction of the wheel and protrudes outward from the tread surface in the radial direction of the wheel; an annular plate portion connecting the boss portion and the rim portion; Equipped with a center of the rim portion in the axial direction is located on the flange side with respect to a center of the boss portion in the axial direction, a plate thickness center line of the plate portion has a straight line in a cross section including a central axis of the wheel, and is inclined with respect to the radial direction so as to move away from the flange as it extends outward in the radial direction, a wheel in which Pw is the axial distance from one of the two axial side surfaces of the rim portion that is farther from the flange to the outer end, which is the end that is located radially outward of both ends of the plate thickness centerline, and Wr is the axial length of the rim portion, and Pw / Wr is less than 0.

40.

2. 2. A wheel according to claim 1, Wheels where Pw / Wr is 0.30 or greater.

3. 2. A wheel according to claim 1, The angle that the plate thickness centerline forms with the axial direction on the opposite side of the flange is 89° or less.

4. 4. A wheel according to claim 3, The angle is greater than or equal to 85°.

5. 2. A wheel according to claim 1, a flange-side surface of the plate portion connected to a surface of the rim portion via a connecting portion having an arc shape when viewed in a cross section including the center axis of the wheel, A wheel, wherein the radius of curvature of the connection portion is 20 mm or more.

6. 2. A wheel according to claim 1, the plate portion has a minimum plate thickness at a position radially inward with respect to the outer end of the plate thickness center line, A wheel in which the thickness of the plate portion decreases toward the outside in the radial direction up to the position of the minimum thickness.

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