Wheel

Abstract

A wheel (100) is provided with a hub section (10), a rim section (20), and a plate section (30). The hub section (10) includes a contour line (14) extending from the plate section (30) toward an axial end surface (12) of the hub section (10) when viewed in a longitudinal cross-section of the wheel (100). The contour line (14) comprises a curved line (141, 142). The first curved line (141) is continuous with the plate section (30). The first curve (141) has a first radius of curvature (R1). The second curve (142) is disposed on the axial end surface (12) side of the hub section (10) with respect to the first curve (141). The second curve (142) has a second radius of curvature (R2). The second radius of curvature (R2) is larger than the first radius of curvature (R1). The length of the second curve (142) is greater than the length of the first curve (141).

Description

Technical Field

[0001] The present disclosure relates to a wheel for a railway vehicle. Background Art

[0002] The wheel for railway vehicles comprises a hub portion, a rim portion and a plate portion. The axle is inserted into the hub portion. The rim portion is arranged on the outer peripheral side of the hub portion. The rim portion includes a tread and a flange. The tread is a surface that contacts the top surface of the rail. The flange is continuously provided with one end of the tread and protrudes toward the outer peripheral side of the wheel relative to the tread. The plate portion connects the rim portion and the hub portion.

[0003] In the past, wheels of various shapes have been proposed. For example, Patent Documents 1 and 2 disclose wheels having a curved plate portion. In Patent Document 1, the plate portion has a substantially S-shaped shape when viewed in a longitudinal section of the wheel. In Patent Document 2, the plate portion has a curved shape that bulges toward one side of the axle when viewed in a longitudinal section of the wheel.

[0004] The wheels of Patent Documents 3 and 4 have a substantially straight plate portion. In the wheels of Patent Documents 3 and 4, the plate portion is inclined with respect to the radial direction of the wheel.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 10-29401

[0008] Patent Document 2: Japanese Patent Application No. 2009-545484

[0009] Patent Document 3: International Publication No. 2020 / 241401

[0010] Patent Document 4: International Publication No. 2022 / 091764 Summary of the invention

[0011] Technical problem to be solved by the invention

[0012] As a basic characteristic, the wheels for railway vehicles are required to have strength. In addition, from the viewpoints of energy saving and aggressiveness to the track, the wheels for railway vehicles are required to be lightweight. That is, the wheels for railway vehicles preferably have the required strength and are as lightweight as possible.

[0013] An object of the present disclosure is to provide a wheel for a railway vehicle that can achieve weight reduction while ensuring strength.

[0014] Technical means for solving technical problems

[0015] The wheel for railway vehicles disclosed in the present invention comprises a hub portion, a rim portion and a plate portion. The hub portion has a cylindrical shape. The rim portion is arranged on the outer peripheral side of the hub portion. The plate portion connects the hub portion and the rim portion. When observing the longitudinal section of the wheel, the hub portion includes a contour line extending from the plate portion to the axial end face of the hub portion. The contour line includes a first curve and a second curve. The first curve is continuous with the plate portion. The first curve is concavely bent toward the inner side of the hub portion and has a first radius of curvature. The second curve is arranged on the axial end face side of the hub portion relative to the first curve. The second curve is concavely bent toward the inner side of the hub portion and has a second radius of curvature. The second radius of curvature is larger than the first radius of curvature. The line length of the second curve is larger than the line length of the first curve.

[0016] Effects of the Invention

[0017] According to the present disclosure, it is possible to achieve weight reduction of a wheel for a railway vehicle while ensuring the strength of the wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a longitudinal sectional view of the wheel for railway vehicles according to the embodiment.

[0019] Figure 2 It is a longitudinal sectional view of a wheel for a railway vehicle according to a modified example of the above-mentioned embodiment.

[0020] Figure 3 It is a longitudinal sectional view of a wheel for a railway vehicle according to another modified example of the above-mentioned embodiment.

[0021] Figure 4 1 is a diagram showing the outer edge of a longitudinal section of a wheel used in the second embodiment.

[0022] Figure 5 1 is a diagram showing the outer edge of a longitudinal section of a wheel used in the third embodiment.

[0023] Figure 6 It shows the outer edge of the longitudinal section of the wheel used in the fourth embodiment.

[0024] Figure 7 This is a graph showing the 1 / 3 octave band frequency characteristics of the equivalent radiated power (ERP). DETAILED DESCRIPTION

[0025] The wheel for railway vehicles of the embodiment comprises a hub portion, a rim portion and a plate portion. The hub portion has a cylindrical shape. The rim portion is arranged on the outer peripheral side of the hub portion. The plate portion connects the hub portion and the rim portion. When the wheel is observed in a longitudinal section, the hub portion includes a contour line extending from the plate portion to the axial end face of the hub portion. The contour line includes a first curve and a second curve. The first curve is continuous with the plate portion. The first curve is concavely bent toward the inner side of the hub portion and has a first radius of curvature. The second curve is arranged on the axial end face side of the hub portion relative to the first curve. The second curve is concavely bent toward the inner side of the hub portion and has a second radius of curvature. The second radius of curvature is larger than the first radius of curvature. The line length of the second curve is greater than the line length of the first curve (first configuration).

[0026] When observing the wheel for railway vehicles in longitudinal section, the hub portion includes a pair of contour lines constituting its outer peripheral surface. One contour line is continuous with the plate portion on the flange side and extends to one axial end face of the cylindrical hub portion. The other contour line is continuous with the plate portion on the opposite side of the flange and extends to the other axial end face of the hub portion. Each contour line is usually composed of a curve that becomes a fillet portion connecting the hub portion and the plate portion, and a straight line extending from the curve to the end face of the hub portion. For example, when the proportion of the straight line in the contour line is large, there is a tendency for the wall thickness of the hub portion to increase. If the wall thickness of the hub portion increases, the weight of the wheel increases.

[0027] In order to make the wheel lighter, for example, it is possible to consider setting the entire contour line of the hub portion to a single curve with a constant radius of curvature. However, in the case where the contour line of the hub portion is formed by a single curve with a constant radius of curvature, it is difficult to ensure a balance between lightness and strength. For example, in order to smoothly connect the hub portion to the plate portion, it is necessary to make the slope of the tangent of the end of the plate portion side of the single curve constituting the contour line of the hub portion consistent with the slope of the contour line of the plate portion. However, in the case where the contour line of the hub portion is constant and extends from the plate portion to the end face of the hub portion with a large radius of curvature, it can be predicted that the wall thickness of the hub portion near the end face of the hub portion becomes very small. Therefore, it is believed that the gripping force of the hub portion on the axle is reduced, that is, the strength of the wheel is insufficient. On the other hand, in order to ensure the wall thickness of the hub portion, it is sufficient to reduce the radius of curvature of the contour line, but in the case of excessively reducing the radius of curvature, the contour line of the hub portion becomes a shape that expands outward in the radial direction near the end face of the hub portion (a shape with terminal expansion). In this case, not only will the weight of the wheel increase, but it is also easy to generate stress concentration at the boundary between the hub portion and the plate portion. Therefore, when the contour line of the hub portion is formed by a single curve having a constant radius of curvature, it is difficult to reduce the weight of the wheel while ensuring the strength of the wheel, and the degree of freedom in wheel design decreases.

[0028] In this regard, in a wheel of the first configuration, the first curve and the second curve are provided on the contour line of the hub portion. The second curve is arranged on the end face side of the hub portion relative to the first curve. By means of the second curve, the outer peripheral surface of the hub portion can be hollowed into a concave shape. Therefore, compared with the case where the portion on the end face side of the hub portion in the contour line of the hub portion is composed of a straight line, the wall thickness of the hub portion can be reduced. Thus, the hub portion and the wheel can be made lightweight. On the other hand, the first curve is a fillet portion connecting the hub portion to the plate portion, and has a smaller radius of curvature than the second curve on the end face side of the hub portion. Since the first curve as the fillet portion is provided separately from the second curve on the end face side of the hub portion, the contour line of the hub portion can be smoothly connected to the plate portion without making the contour line of the hub portion in a shape with an extended end. Therefore, stress concentration at the boundary between the hub portion and the plate portion can be suppressed, and the strength of the wheel can be ensured.

[0029] As described above, according to the first configuration, it is possible to reduce the weight of the wheel while ensuring the strength of the wheel for a railway vehicle.

[0030] In addition to being lightweight, wheels for railway vehicles are also required to be quiet for environmental reasons. However, there is a trade-off between improving the quietness of the wheels and reducing the weight of the wheels. That is, if the quietness of the wheels during the travel of railway vehicles is to be improved, the weight of the wheels is usually increased.

[0031] The inventors of the present invention have carried out a frequency response analysis based on the finite element method using general structural analysis software to determine the parts that affect the quietness in the wheels for railway vehicles. In this analysis, a force assuming a track reaction force is applied to the tread of a 360° wheel model, and the responsiveness to the vibration at that time is evaluated. The equivalent radiated power (ERP) calculated according to the following formula is used as an evaluation index.

[0032] [Formula 1]

[0033]

[0034] In the above formula, ΔS i is the element area of ​​the wheel surface, V ni It is the vibration speed in the normal direction of the surface. c is a coefficient determined by atmospheric conditions, etc. The larger the ERP, the higher the ability to radiate sound. The material of the wheel is carbon steel with a carbon content of 0.7%.

[0035] Figure 7 This is a graph obtained by performing frequency response analysis, and is a diagram showing the 1 / 3 octave band frequency characteristics of ERP. Figure 7 The OA in is the sum of the energy of all frequencies (total ERP level). Figure 7As shown in the figure, the ERP levels at frequencies A, B, and C are larger than those at other frequency bands, confirming that frequencies A, B, and C contribute more to OA. Therefore, when investigating the deformation modes of the wheel at frequencies A, B, and C, it can be seen that the displacement of the hub is very small compared to the rim and plate. Therefore, it can be said that the influence of the shape of the hub on ERP, in other words, the influence on the quietness of the wheel, is slight.

[0036] Based on the new insight that the shape of the hub portion has a slight effect on the quietness of the wheel, in the first configuration, the shape of the hub portion is studied to reduce its weight. More specifically, in the contour line of the hub portion, the second curve with a larger curvature radius is arranged closer to the end face of the hub portion than the first curve as the fillet portion, thereby reducing the wall thickness of the hub portion while ensuring the rigidity of the plate portion that contributes greatly to the quietness. As a result, the wheel can be lightweight while maintaining the quietness of the wheel during the travel of the railway vehicle.

[0037] The second radius of curvature is preferably not less than 108 mm and less than 700 mm (second configuration).

[0038] In the second configuration, the radius of curvature of the second curve on the end surface side of the hub portion in the contour line of the hub portion extending from the plate portion is greater than 108 mm and less than 700 mm. In this case, the wheel can be made lighter while improving the quietness of the wheel during travel of the railway vehicle.

[0039] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, the same or corresponding components are denoted by the same reference numerals, and the same description will not be repeated.

[0040] [Wheel structure]

[0041] Figure 1 1 is a longitudinal cross-sectional view of a wheel 100 for a railway vehicle according to the present embodiment. The longitudinal cross-section of the wheel 100 refers to a cross-section of the wheel 100 including the central axis X. Since the longitudinal cross-section of the wheel 100 is symmetrical with respect to the central axis X, Figure 1 1 shows only one side of the center axis X in the wheel 100. In the present embodiment, the direction in which the center axis X of the wheel 100 extends is referred to as an axial direction. In the present embodiment, the radial direction of the wheel 100 is sometimes referred to simply as a radial direction.

[0042] Reference Figure 1 The wheel 100 includes a hub portion 10 , a rim portion 20 , and a plate portion 30 .

[0043] The hub portion 10 constitutes the inner peripheral portion of the wheel 100. The hub portion 10 has a cylindrical shape. An axle (not shown) of a railway vehicle is inserted into the hub portion 10.

[0044] The rim portion 20 is disposed on the outer peripheral side of the hub portion 10. The rim portion 20 constitutes the outer peripheral portion of the wheel 100. The rim portion 20 includes a tread 21 and a flange 22.

[0045] The tread 21 is provided on the outer peripheral surface of the rim portion 20. The tread 21 is a surface facing outward in the radial direction of the wheel 100. The tread 21 is in contact with the top surface of the rail on which the railway vehicle runs.

[0046] The flange 22 is provided continuously with one end of the tread 21 in the axial direction of the wheel 100. The flange 22 protrudes radially outward relative to the tread 21. When the railway vehicle travels on the track, the flange 22 is located on the inner side of the track in the track width direction. Hereinafter, the side closer to the flange 22 in the axial direction is referred to as the flange side, and the side farther from the flange 22 in the axial direction is referred to as the anti-flange side.

[0047] In the example of this embodiment, the rim portion 20 is located inside the track width direction relative to the hub portion 10. More specifically, the rim width center Cr is located on the flange side relative to the boss width center Cb. The rim width center Cr is the center of the rim portion 20 in the axial direction of the wheel 100. The boss width center Cb is the center of the hub portion 10 in the axial direction of the wheel 100.

[0048] The plate portion 30 is annular and connects the hub portion 10 and the rim portion 20. The plate portion 30 is formed integrally with the hub portion 10 and the rim portion 20. In the example of this embodiment, the plate portion 30 is substantially straight when viewed in a longitudinal section of the wheel 100. The plate portion 30 may also be inclined relative to the radial direction of the wheel 100. Figure 1 In the example of FIG. 5 , the plate portion 30 is inclined with respect to the radial direction so that the outer peripheral portion of the plate portion 30 is arranged on the anti-flange side relative to the inner peripheral portion.

[0049] Next, refer to Figure 1 , the structure of the hub portion 10 will be described in more detail.

[0050] like Figure 1 As shown, the hub portion 10 includes an inner circumferential surface 11 , end surfaces 12 , 13 , a contour line 14 , and a corner portion 15 .

[0051] When the wheel 100 is viewed from a longitudinal section, the inner peripheral surface 11 of the hub portion 10 extends in the axial direction of the wheel 100. When the wheel 100 is viewed from a longitudinal section, the end surfaces 12 and 13 of the hub portion 10 are continuous with both ends of the inner peripheral surface 11 and extend radially outward from the inner peripheral surface 11. One end surface 12 is arranged on the opposite flange side relative to the other end surface 13.

[0052] When viewed from the longitudinal section of the wheel 100, the contour line 14 of the hub portion 10 is arranged radially outward relative to the inner peripheral surface 11. When viewed from the longitudinal section of the wheel 100, the contour line 14 extends from the plate portion 30 to the end surface 12 on the anti-flange side of the hub portion 10. When viewed from the longitudinal section of the wheel 100, the contour line 14 is continuously provided with the contour line 31 on the anti-flange side of the plate portion 30. In addition, the contour line 14 is substantially connected to the end surface 12 on the anti-flange side of the hub portion 10 via the arc-shaped corner portion 15. The contour line 14 includes a first curve 141 and a second curve 142.

[0053] The first curve 141 is continuous with the plate portion 30. When the wheel 100 is viewed in a longitudinal section, the first curve 141 is disposed adjacent to the contour line 31 of the plate portion 30 on the anti-flange side. The first curve 141 is smoothly connected to the contour line 31 of the plate portion 30. When viewed in a longitudinal section of the wheel 100, the first curve 141 is curved concavely toward the inside of the hub portion 10. The first curve 141 is a rounded corner portion connecting the hub portion 10 and the plate portion 30.

[0054] The second curve 142 is arranged on the end surface 12 side of the hub portion 10 relative to the first curve 141. In the example of this embodiment, the second curve 142 is provided continuously with the first curve 141. The second curve 142 extends from the first curve 141 to the corner 15. The second curve 142 is curved concavely toward the inside of the hub portion 10.

[0055] The first curve 141 has a radius of curvature R1. The second curve 142 has a radius of curvature R2. The radius of curvature R2 of the second curve 142 is greater than the radius of curvature R1 of the first curve 141 as a rounded corner. The radius of curvature R2 of the second curve 142 is, for example, 2.0 times or more, preferably 2.5 times or more, of the radius of curvature R1 of the first curve 141. The radius of curvature R2 of the second curve 142 is preferably 108 mm or more and less than 700 mm. The radius of curvature R2 of the second curve 142 is more preferably 108 mm or more and 200 mm or less, and further preferably 110 mm or more and 200 mm or less. The radius of curvature R1 of the first curve 141 is, for example, 50 mm or less. The radius of curvature R1 of the first curve 141 may also be 30 mm or more.

[0056] When observing the longitudinal section of the wheel 100, the line length of the second curve 142 is greater than the line length of the first curve 141. That is, the proportion of the second curve 142 in the contour line 14 of the hub portion 10 is greater than the proportion of the first curve 141. The line length of the second curve 142 is, for example, more than 1 / 3 of the line length of the entire contour line 14. The line length of the second curve 142 is preferably more than 2 / 5 of the line length of the entire contour line 14, and more preferably more than 2 / 3. The line length of the entire contour line 14 refers to the length along the outer shape of the wheel 100 from the boundary between the contour line 31 of the plate portion 30 and the first curve 141 to the R angle of the corner 15 on the opposite side of the end face 12.

[0057] The first curve 141 is a single curve having a substantially certain radius of curvature when observed in the longitudinal section of the wheel 100. The second curve 142 can be any line that can be identified as a continuous curve when observed in the longitudinal section of the wheel 100. For example, in the case where a curve is simulated by connecting a plurality of straight lines of smaller lengths, the simulated curve can be regarded as a continuous curve. In addition, for example, in the case where a curve is simulated by a mixture of straight lines and curves of smaller lengths, the simulated curve can also be regarded as a continuous curve. In the present embodiment, a line extending with a radius of curvature less than 1000 mm is defined as a curve.

[0058] The first curve 141 and the second curve 142 can be determined as follows.

[0059] In the longitudinal section of the wheel 100, there is usually a point where the curvature changes at the boundary between the contour line 31 of the plate portion 30 and the contour line 14 of the hub portion 10. A single curve extending from the curvature change point in the radial direction toward the inner side and the end surface 12 side of the hub portion 10 with a certain curvature radius can be determined as the first curve 141.

[0060] The second curve 142 exists in an area radially inward of the first curve 141 in the contour line 14 of the hub portion 10. In this area, a line that can be identified as a continuous curve in appearance can be determined as the second curve 142. For example, a clear straight line with a line length exceeding 90 mm, a broken line forming a characteristic shape such as a concave-convex shape, etc. is not included in the line that can be identified as a curve. The radius of curvature R2 of the second curve 142 can be set to the radius of curvature when the line that can be identified as a curve is approximated as an arc. In the case where there are multiple lines that can be identified as a continuous curve in an area radially inward of the first curve 141 in the contour line 14 of the hub portion 10, the line whose radius of curvature when approximated as an arc is larger than the radius of curvature R1 of the first curve 141 and whose line length is the largest is the second curve 142.

[0061] When the axial distance between the two end faces 12 and 13 of the hub portion 10 is set as the overall width W0 of the hub portion 10, and the axial distance from the end face 12 on the side of the contour line 14 to the bending vertex of the first curve 141 is set as the width W1 of the contour line 14, it is preferred that the width W1 of the contour line 14 accounts for a large proportion of the overall width W0 of the hub portion 10. The overall width W0 of the hub portion 10 and the width W1 of the contour line 14 preferably satisfy W1 / W0≧0.5, and more preferably satisfy W1 / W0≧0.6. The upper limit of W1 / W0 is not particularly limited, and is, for example, W1 / W0≦0.8.

[0062] like Figure 1 As shown, the hub portion 10 has a hub thickness T. The hub thickness T is the length in the radial direction from the inner circumferential surface 11 of the hub portion 10 to the boundary between the contour line 14 and the corner portion 15 (the R angle of the corner portion 15). From the viewpoint of ensuring the force of the hub portion 10 to grip the axle, the hub thickness T is preferably greater than 10 mm. The hub thickness T may also be greater than 20 mm. The hub thickness T is, for example, less than 60 mm. The hub thickness T is preferably less than 45 mm.

[0063] Although not particularly limited, such a wheel 100 can be manufactured by, for example, forging, casting, or machining (cutting) of a forged product or a cast product. The material of the wheel 100 is preferably carbon steel.

[0064] [Effect]

[0065] In the wheel 100 of the present embodiment, a first curve 141 is provided in the contour line 14 of the hub portion 10. The first curve 141 is adjacent to the contour line 31 of the plate portion 30 and has a small radius of curvature R1. Through the first curve 141, the contour line 14 of the hub portion 10 and the contour line 31 of the plate portion 30 are smoothly connected. In addition, the first curve 141 does not extend to the vicinity of the end face 12 of the hub portion 10, so that the contour line 14 can be prevented from becoming a shape that expands toward the end of the end face 12. Therefore, it is difficult to generate stress concentration at the boundary between the contour line 14 of the hub portion 10 and the contour line 31 of the plate portion 30. As a result, the strength of the wheel 100 can be ensured.

[0066] In the wheel 100 of the present embodiment, a second curve 142 is further provided in the contour line 14 of the hub portion 10. The second curve 142 is arranged on the end face 12 side of the hub portion 10 relative to the first curve 141. The second curve 142 extends toward the end face 12 of the hub portion 10 while hollowing the outer peripheral surface of the hub portion 10 into a concave shape with a larger curvature radius R2. As a result, the hub thickness T on the end face 12 side can be reduced. Therefore, the wheel 100 including the hub portion 10 and the hub portion 10 can be made lightweight.

[0067] As described above, according to the present embodiment, it is possible to reduce the weight of the wheel 100 while ensuring the required strength for the railway wheel 100 .

[0068] When the wheel 100 is running, the hub portion 10 is less likely to deform than the rim portion 20 and the plate portion 30, and the shape of the hub portion 10 has little effect on the quietness of the wheel 100. Therefore, in the present embodiment, in the contour line 14 of the hub portion 10, in addition to the first curve 141 as the rounded corner portion, the second curve 142 having a larger curvature radius R2 is provided on the end face 12 side of the hub portion 10, so that the wall thickness of the hub portion 10 can be reduced. In this case, the weight of the wheel 100 including the hub portion 10 and the hub portion 10 can be reduced without substantially reducing the quietness of the wheel 100.

[0069] In the present embodiment, the radius of curvature R2 of the second curve 142 is preferably not less than 108 mm and less than 700 mm. This can reduce the weight of the wheel 100 and improve the quietness of the wheel 100 during the travel of the railway vehicle. From the viewpoint of further reducing the weight of the wheel 100, the radius of curvature R2 of the second curve 142 is more preferably not less than 108 mm and not more than 200 mm, and further preferably not less than 110 mm and not more than 200 mm.

[0070] In the wheel 100 of the present embodiment, it is preferred that the width W1 of the contour line 14 accounts for a large proportion of the overall width W0 of the hub portion 10. The overall width W0 of the hub portion 10 and the width W1 of the contour line 14 preferably satisfy W1 / W0≧0.5, and more preferably satisfy W1 / W0≧0.6. In the case where W1 / W0 is large, it is easy to ensure the line length of the second curve 142 included in the contour line 14. That is, the area in the hub portion 10 that is dug into a concave shape by the second curve 142 is easy to become larger. Therefore, compared with the case where W1 / W0 is small, in the case where W1 / W0 is large, even if the radius of curvature R2 of the second curve 142 is the same, it can have a higher effect on the lightweighting of the wheel 100.

[0071] As mentioned above, although embodiment of this disclosure was described, this disclosure is not limited to the said embodiment, Various changes can be made without departing from the range which concerns on this disclosure.

[0072] In the wheel 100 of the above embodiment, the rim width center Cr is located on the flange side relative to the boss width center Cb. In addition, in the above embodiment, the plate portion 30 has a substantially straight shape when viewed in a longitudinal section of the wheel 100. Furthermore, in the above embodiment, the contour line 14 of the hub portion 10 including the curves 141 and 142 is provided continuously with the contour line 31 of the plate portion 30 on the anti-flange side. However, the shape of the wheel 100 and the portion where the contour line 14 is provided are not limited to the examples of the above embodiment.

[0073] For example, Figure 2 As in the wheel 100 shown in FIG. 1 , the rim width center Cr may be located on the anti-flange side relative to the boss width center Cb. Figure 2 As shown, the plate portion 30 may also be curved when viewed in the longitudinal section of the wheel 100. Figure 2 In the example, the contour line 14 of the hub portion 10 is the same as the above embodiment, and is continuously provided with the contour line 31 on the anti-flange side of the plate portion 30. However, the contour line 14 including the curves 141 and 142 may also be continuously provided with the contour line 32 on the flange side of the plate portion 30.

[0074] For example, Figure 3 Even when the rim width center Cr is located on the flange side relative to the boss width center Cb, as in the wheel 100 shown in the figure, the contour line 14 of the hub portion 10 can be provided continuously with the contour line 32 on the flange side of the plate portion 30. In this case, when viewed from the longitudinal section of the wheel 100, the contour line 14 extends from the contour line 32 on the flange side of the plate portion 30 and is connected to the end face 13 on the flange side of the hub portion 10 via the corner portion 15.

[0075] As described above, the contour line 14 of the hub portion 10 described in the above embodiment can be applied regardless of the basic shape of the railway vehicle wheel. The contour line 14 including the curves 141 and 142 only needs to be provided adjacent to at least one of the contour line 31 on the anti-flange side and the contour line 32 on the flange side of the plate portion 30.

[0076] In the above embodiment, the contour line 14 of the hub portion 10 is composed of two curves 141 and 142. However, the contour line 14 may include three or more curves with different curvature radii. In the case where the contour line 14 includes three or more curves, the curve disposed at the position closest to the plate portion 30 among these curves is the first curve 141, and the curve having a larger curvature radius than the curvature radius R1 of the first curve 141 and the largest line length among the remaining curves is the second curve 142. From the viewpoint of sufficiently ensuring the line length of the second curve 142 and effectively reducing the weight of the hub portion 10, the number of curves included in the contour line 14, that is, the number of lines regarded as a continuous curve, is preferably four or less.

[0077] The contour line 14 of the hub portion 10 may include one or more straight lines in addition to the plurality of curves. The straight line referred to herein refers to a region in the contour line 14 that has a line length of more than 90 mm and a radius of curvature of more than 1000 mm, for example. When the contour line 14 includes one or more straight lines, the line length of the straight line is significantly less than the line length of the second curve 142.

[0078] Hereinafter, the present disclosure will be described in further detail using examples, but the present disclosure is not limited to the following examples.

[0079] [First embodiment]

[0080] In order to confirm the effect of the present disclosure, Figure 1 The shape of the wheel 100 shown was analyzed based on the finite element method using general structural analysis software. In this analysis, the force of the assumed track reaction force is applied to the tread of the 360° wheel model, and the responsiveness to the vibration at this time is evaluated as the quietness of the wheel. The evaluation of quietness uses the above-mentioned equivalent radiated power (total ERP level). The conditions and results of this analysis are shown in Table 1.

[0081] [Table 1]

[0082] Table 1

[0083] The radius of curvature of the second curve R2 (mm) Hub thickness T(mm) Hub width ratio W1 / W0 Weight(kg) Quietness index Example 1 112 22 0.70 8.6 0.02 Example 2 130 26 0.70 6.1 0.02 Example 3 144 30 0.70 4.2 0.03 Example 4 183 36 0.69 1.7 0.04 Example 5 700 46 0.67 0.1 0.00 Comparative Example 1 ∞ 36 0.70 0.0 0.00 Example 6 107 10 0.71 14.1 -0.06

[0084] ※1 "Weight" is the difference from the weight of Comparative Example 1. When it is a positive value, it is lighter than Comparative Example 1.

[0085] ※2 "Quietness Index" is the difference from the ERP level of Comparative Example 1. When it is a positive value, the quietness is better than that of Comparative Example 1.

[0086] In the "Weight" column in Table 1, the value obtained by subtracting the wheel weight of each example from the wheel weight of Comparative Example 1 (the difference between each example and Comparative Example 1) is shown. In the "Quietness Index" column in Table 1, the value obtained by subtracting the total ERP level of each example from the total ERP level of Comparative Example 1 (the difference between each example and Comparative Example 1) is shown. If the weight in Table 1 is a positive value, it means that the wheel is lighter than that of Comparative Example 1. If the quietness index in Table 1 is a positive value, it means that the quietness of the wheel is improved compared with that of Comparative Example 1. Comparative Example 1 sets a straight line in the contour line 14 on the outer peripheral side of the hub portion 10 instead of the second curve 142. Therefore, in Table 1, the curvature radius R2 of the second curve 142 of Comparative Example 1 is expressed as ∞. The curvature radius R1 of the first curve 141 is the same in Examples 1 to 6 and Comparative Example 1, and is smaller than the curvature radius R2 of the second curve 142 in Examples 1 to 6.

[0087] As shown in Table 1, for any one of Examples 1 to 6, the difference in weight from Comparative Example 1 is a positive value, and the wheel is lighter than that of Comparative Example 1. Such lightweighting of the wheel has a great influence on the lightweighting of the entire railway vehicle using the wheel and the entire train. That is, since the railway vehicle has two front and rear bogies, each bogie is equipped with four wheels, each vehicle is provided with eight wheels. Therefore, when the weight of the wheel is reduced, the weight of the entire railway vehicle is reduced by eight times the amount of weight reduction per wheel. In a train composed of multiple railway vehicles, the weight reduction is performed by eight times the amount of weight reduction per wheel × the number of vehicles.

[0088] As shown in Table 1, the quietness indexes of Examples 1 to 6 are all at or above the same level as those of Comparative Example 1, and quietness equal to or higher than that of Comparative Example 1 can be ensured.

[0089] In Example 5, in which the radius of curvature R2 of the second curve 142 is set to 700 mm, the quietness of the wheel is the same as that of Comparative Example 1. In addition, in Example 6, in which the radius of curvature R2 of the second curve 142 is set to 107 mm, the weight of the wheel is greatly reduced compared with Comparative Example 1, but the quietness of the wheel is only slightly reduced compared with the Comparative Example. On the other hand, in Examples 1 to 4, in which the radius of curvature R2 of the second curve 142 is in the range of 108 mm or more and less than 700 mm, the quietness of the wheel is improved compared with Comparative Example 1.

[0090] In Examples 1 to 4, the radius of curvature R2 of the second curve 142 is 200 mm or less. In Examples 1 to 4, the weight of the wheel is reduced to a greater extent than that of Comparative Example 1.

[0091] According to this analysis, it was confirmed that by providing the second curve 142 in the contour line 14 of the hub portion 10, it is possible to achieve lightweighting of the wheel while maintaining the quietness of the wheel during the travel of the railway vehicle. In particular, it is known that when the radius of curvature R2 of the second curve 142 is set to be greater than 108 mm and less than 700 mm, the quietness becomes good. In addition, it was confirmed that when the radius of curvature R2 of the second curve 142 is less than 200 mm, it is easier to make the wheel lightweight.

[0092] [Second embodiment]

[0093] The same analysis and evaluation as in the first embodiment were performed on a wheel having a different shape from that in the first embodiment. The outer edge of the longitudinal section of the wheel used in this analysis is shown in FIG. Figure 4 .

[0094] In the first embodiment, the contour line 14 including the first curve 141 and the second curve 142 is provided on the anti-flange side ( Figure 1), in contrast, in the second embodiment, as Figure 4 As shown, the contour line 14 including the first curve 141 and the second curve 142 is set on the flange side. In addition, in the first embodiment, the plate portion 30 is inclined with respect to the radial direction in such a manner that the outer peripheral portion is located on the anti-flange side relative to the inner peripheral portion, whereas in the second embodiment, the plate portion 30 is inclined with respect to the radial direction in such a manner that the outer peripheral portion is located on the flange side relative to the inner peripheral portion, which is opposite to the first embodiment. Furthermore, in the first embodiment, the rim width center Cr is located on the flange side relative to the boss width center Cb, whereas in the second embodiment, the rim width center Cr is located on the anti-flange side relative to the boss width center Cb.

[0095] Table 2 shows the conditions and results of this analysis.

[0096] [Table 2]

[0097] Table 2

[0098] The radius of curvature of the second curve R2 (mm) Hub thickness T(mm) Hub width ratio W1 / W0 Weight(kg) Quietness index Example 7 112 22 0.68 8.5 0.05 Example 8 130 26 0.70 5.9 0.03 Example 9 183 36 0.71 1.6 0.01 Comparative Example 2 ∞ 36 0.72 0.0 0.00

[0099] ※1 "Weight" is the difference from the weight of Comparative Example 2. When it is a positive value, it is lighter than Comparative Example 2.

[0100] ※2 "Quietness Index" is the difference from the ERP level of Comparative Example 2. When it is a positive value, the quietness is better than that of Comparative Example 2.

[0101] In the "Weight" column in Table 2, the value obtained by subtracting the wheel weight of each example from the wheel weight of Comparative Example 2 (the difference between each example and Comparative Example 2) is shown. In the "Quietness Index" column in Table 2, the value obtained by subtracting the total ERP level of each example from the total ERP level of Comparative Example 2 (the difference between each example and Comparative Example 2) is shown. If the weight in Table 2 is a positive value, it means that the wheel is lighter than that of Comparative Example 2. If the quietness index in Table 2 is a positive value, it means that the quietness of the wheel is improved compared to that of Comparative Example 2. Comparative Example 2 has a positive value. Figure 4 In the outline 14 of the hub portion 10 of the wheel shape shown, a straight line is provided instead of the second curve 142. Therefore, in Table 2, the curvature radius R2 of the second curve 142 of Comparative Example 2 is indicated as ∞. The curvature radius R1 of the first curve 141 is the same in Examples 7 to 9 and Comparative Example 2, and is smaller than the curvature radius R2 of the second curve 142 in Examples 7 to 9.

[0102] As shown in Table 2, the weight difference between Examples 7 to 9 and Comparative Example 2 is positive, and the wheel is lighter than Comparative Example 2. In addition, the quietness index of Examples 7 to 9 is positive, and the quietness is improved compared with Comparative Example 2.

[0103] According to this analysis, even for a wheel shape different from that of the first embodiment, it was confirmed that by providing the second curve 142 in the contour line 14 of the hub portion 10, it is possible to achieve weight reduction while ensuring quietness of the wheel during travel of the railway vehicle.

[0104] [Third embodiment]

[0105] The same analysis and evaluation as above were performed on wheels having different shapes from those of the first and second embodiments. The outer edge of the longitudinal section of the wheel used in this analysis is shown in FIG. Figure 5 .

[0106] like Figure 5 As shown, in the third embodiment, unlike the first and second embodiments, the plate portion 30 is curved. In the third embodiment, a wheel shape in which the rim width center Cr is located on the anti-flange side relative to the boss width center Cb is used.

[0107] Table 3 shows the conditions and results of this analysis.

[0108] [Table 3]

[0109] Table 3

[0110] The radius of curvature of the second curve R2 (mm) Hub thickness T(mm) Hub width ratio W1 / W0 Weight(kg) Quietness index Example 10 107 20 0.51 1.6 0.40 Comparative Example 3 ∞ 32 0.44 0.0 0.00

[0111] ※1 "Weight" is the difference from the weight of Comparative Example 3. When it is a positive value, it is lighter than Comparative Example 3.

[0112] ※2 "Quietness index" is the difference from the ERP level of Comparative Example 3. When it is a positive value, the quietness is better than that of Comparative Example 3.

[0113] In the "Weight" column in Table 3, the value obtained by subtracting the wheel weight of each example from the wheel weight of Comparative Example 3 (the difference between each example and Comparative Example 3) is shown. In the "Quietness Index" column in Table 3, the value obtained by subtracting the total ERP level of each example from the total ERP level of Comparative Example 3 (the difference between each example and Comparative Example 3) is shown. If the weight in Table 3 is a positive value, it means that the wheel is lighter than that of Comparative Example 3. If the quietness index in Table 3 is a positive value, it means that the quietness of the wheel is improved compared to that of Comparative Example 3. Comparative Example 3 has a positive value. Figure 5 In the outline 14 of the hub portion 10 of the wheel shape shown, a straight line is provided instead of the second curve 142. Therefore, in Table 3, the curvature radius R2 of the second curve 142 of Comparative Example 3 is represented as ∞. The curvature radius R1 of the first curve 141 is the same in Example 10 and Comparative Example 3, and is smaller than the curvature radius R2 of the second curve 142 in Example 10.

[0114] As shown in Table 3, in Example 10, the difference in weight from Comparative Example 3 is a positive value, and the wheel is lighter than Comparative Example 3. In addition, in Example 10, the quietness index is a positive value, and the quietness is improved compared with Comparative Example 3.

[0115] According to this analysis, even for wheel shapes different from those in the first and second embodiments, it was confirmed that by providing the second curve 142 in the contour line 14 of the hub portion 10, it is possible to achieve weight reduction while ensuring quietness of the wheel during travel of the railway vehicle.

[0116] [Fourth embodiment]

[0117] The same analysis and evaluation as above were performed on wheels having different shapes from those of the first to third embodiments. The outer edge of the longitudinal section of the wheel used in this analysis is shown in FIG. Figure 6 .

[0118] The wheel shape of the fourth embodiment is based on the commonly circulated wheel shape. Figure 6 As shown in FIG. 1 , in the fourth embodiment, the plate portion 30 is curved in the same manner as in the third embodiment, but a wheel shape is used in which the rim width center Cr is located on the flange side relative to the boss width center Cb. In addition, in the third embodiment, the contour line 14 including the first curve 141 and the second curve 142 is provided on the anti-flange side ( Figure 5 ), in contrast, in the fourth embodiment, as Figure 6 As shown, the contour line 14 including the first curve 141 and the second curve 142 is provided on the flange side.

[0119] Table 4 shows the conditions and results of this analysis.

[0120] [Table 4]

[0121] Table 4

[0122] The radius of curvature of the second curve R2 (mm) Hub thickness T(mm) Hub width ratio W1 / W0 Weight(kg) Quietness index Embodiment 11 107 21 0.30 1.7 0.40 Comparative Example 4 ∞ 32 0.30 0.0 0.00

[0123] ※1 "Weight" is the difference from the weight of Comparative Example 4. When it is a positive value, it is lighter than Comparative Example 4.

[0124] ※2 "Quietness index" is the difference from the ERP level of Comparative Example 4. When it is a positive value, the quietness is better than that of Comparative Example 4.

[0125] In the "Weight" column in Table 4, the value obtained by subtracting the wheel weight of each example from the wheel weight of Comparative Example 4 (the difference between each example and Comparative Example 4) is shown. In the "Quietness Index" column in Table 4, the value obtained by subtracting the total ERP level of each example from the total ERP level of Comparative Example 4 (the difference between each example and Comparative Example 4) is shown. If the weight in Table 4 is a positive value, it means that the wheel is lighter than that of Comparative Example 4. If the quietness index in Table 4 is a positive value, it means that the quietness of the wheel is improved compared to that of Comparative Example 4. Comparative Example 4 Figure 6 In the outline 14 of the hub portion 10 of the wheel shape shown, a straight line is provided instead of the second curve 142. Therefore, in Table 4, the curvature radius R2 of the second curve 142 of Comparative Example 4 is represented as ∞. The curvature radius R1 of the first curve 141 is the same in Example 11 and Comparative Example 4, and is smaller than the curvature radius R2 of the second curve 142 in Example 11.

[0126] As shown in Table 4, in Example 11, the difference in weight from Comparative Example 4 is a positive value, and the wheel is lighter than Comparative Example 4. In addition, in Example 11, the quietness index is a positive value, and the quietness is improved compared with Comparative Example 4.

[0127] According to this analysis, even for wheel shapes different from those in the first to third embodiments, it has been confirmed that by providing the second curve 142 in the contour line 14 of the hub portion 10, it is possible to achieve weight reduction while ensuring quietness of the wheel during travel of the railway vehicle.

[0128] Description of Reference Numerals

[0129] 100: Wheel

[0130] 10: Hub

[0131] 12, 13: End face

[0132] 14: Contour lines

[0133] 141: The First Curve

[0134] 142: The Second Curve

[0135] 20: Rim

[0136] 30: Board

[0137] R1, R2: radius of curvature

Claims

1. A wheel, which is a wheel for a railway vehicle, comprising: a cylindrical hub portion; a rim portion disposed on an outer peripheral side of the hub portion; and a plate portion connecting the hub portion and the rim portion, When the wheel is viewed in a longitudinal section, the hub portion includes a contour line extending from the plate portion to an axial end surface of the hub portion. The contour lines include: a first curve, which is continuous with the plate portion, is concavely curved toward the inner side of the hub portion, and has a first curvature radius; as well as a second curve, which is arranged on the end surface side of the hub portion relative to the first curve, is curved concavely toward the inside of the hub portion, and has a second curvature radius greater than the first curvature radius; The line length of the second curve is greater than the line length of the first curve.

2. The wheel according to claim 1, The second curvature radius is greater than or equal to 108 mm and less than 700 mm.

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