Axle bearing for railway vehicle

Abstract

A multi-row tapered roller bearing (20) that rotatably supports an axle to which a wheel of a railway vehicle is attached, the multi-row tapered roller bearing (20) having an outer ring (21), an inner ring (23), and a plurality of tapered rollers (22) that are arranged so as to be capable of rolling between the outer ring (21) and the inner ring (23), the multi-row tapered roller bearing (20) being provided with: a seal member (30) that seals the outer ring (21) and the inner ring (23); the bearing is installed on the outer ring (21) and extends from the outer ring (21) to the inner side in the radial direction. And a first-stage radial step section (26) formed on the outer diameter section (25) of the inner ring (23) adjacent to the inner diameter section of the seal member (30). Two-stage radial gaps (41, 42) are formed between the inner diameter portion of the seal member (30) and the outer diameter portion (25) of the inner ring (23) in which the stepped portion (26) is formed.

Description

Technical Field

[0001] This invention relates to a railway vehicle axle bearing that enables the axle of a railway vehicle to rotate freely. Background Technology

[0002] Typically, a railway vehicle bearing unit is installed at the end of the axle of a railway vehicle to support the axle so that it can rotate freely and to support the weight of the vehicle.

[0003] Such railway vehicle bearing units typically include a multi-row tapered roller bearing (hereinafter, also simply "bearing"), which serves as an example of a railway vehicle axle bearing, supporting the railway vehicle axle. The bearing has a single outer ring and two inner rings, each divided into rows. Multiple tapered rollers, held in a retainer, are arranged to roll freely between the two rows of raceway surfaces of the outer and inner rings. Sealing devices (also called "seals") are located at both axial ends of the bearing.

[0004] Previously, bearings used in the bogies of railway vehicles were critical components. Therefore, during regular vehicle inspections, bearings were disassembled and inspected; those without abnormalities were reassembled and reused. Furthermore, due to the decline in the workforce in recent years, there is a need to extend the regular inspection cycle of railway vehicles and reduce maintenance. Additionally, from the perspective of environmental contributions such as CO2 reduction, railway vehicle axle bearings (hereinafter referred to as "axle bearings" or "railway vehicle bearings") require improved reliability and longer lifespan, as well as lighter weight and space-saving design. Therefore, for future axle bearings, while bearing high loads and maintaining long-term lubrication, improved maintainability through disassembly, lighter weight, and space-saving design become added value.

[0005] However, the axle bearings that support the wheel axles (wheels and axles) of railway vehicles have the function of supporting the weight of the vehicle and enabling the wheels to rotate, and they bear high loads along with vibrations during operation. Therefore, most axle bearings use a structure with a sealing device to seal and retain grease inside the bearing.

[0006] Patent Document 1 discloses a sealing device with a notch for inserting a disassembly tool on its outer diameter portion to improve disassembly. This sealing device forms a contact seal between sealing components fixed to both axial ends of the outer ring and oil-retaining rings disposed on both axial sides of the inner ring, resulting in a structure with a relatively large axial width.

[0007] Furthermore, Patent Document 2 discloses a bearing device for railway vehicles, in which a stepped portion is provided on the outer peripheral surface of the inner ring extension portion, which extends in the width direction beyond the outer ring, allowing a sealing member to fall into it, thus facilitating the disassembly of the sealing member. This bearing device for railway vehicles is configured such that the width of the inner ring extending from the inner ring extension portion, which provides sliding contact with the sealing member, is greater than the width of the outer ring, and this width is larger in the axial direction.

[0008] Furthermore, Patent Document 3 discloses a multi-row tapered roller bearing in which a seal is installed at the opening of the annular space formed between the outer and inner rings. The seal consists of a sealing plate and an oil slinger ring. The sealing plate has a sealing component integrally joined to the core of the end fitting into the inner circumference of the outer ring, and the oil slinger ring is fitted into the outer diameter of the inner ring. This seal has a compact assembly width, but also a large number of components.

[0009] Furthermore, Patent Document 4 discloses a sealing device in which a guide portion is provided on the rigid portion of the outer sealing member to guide a component that is pulled by hand or a jig. This sealing device has a compact assembly width, but due to the complex sealing shape, it forms a structure where the width of the inner ring is greater than the width of the outer ring, and the width is larger in the axial direction.

[0010] In addition, bearings for railway vehicles are lubricated by grease or oil. As a method to maintain the function of these lubricants and to maintain a good lubrication environment, methods of using suitable lubricants with suitable sealing structures are listed.

[0011] As a lubricant used in bearings, for example, Patent Document 5 discloses a railway vehicle bearing in which a specific water-resistant grease is sealed around the rolling elements. According to the bearing described in Patent Document 5, even if water is mixed into the bearing, the effect of water on hindering oil film formation can be suppressed, metal-to-metal contact on the rolling surfaces can be suppressed, and premature peeling can be prevented.

[0012] Furthermore, Patent Document 6 proposes a railway vehicle axle assembly in which a cover component is fixedly provided on the outer peripheral surface of the rear cover. According to the axle assembly described in Patent Document 6, water can be prevented from entering the rolling bearing, thus preventing rust and peeling of the bearing.

[0013] Furthermore, Patent Document 7 describes a railway vehicle axle bearing unit that divides the rear cover into two axially arranged split rear covers and provides a lubricant receiving recess at a specific location. According to the bearing unit described in Patent Document 7, fretting wear at the end face of the bearing inner ring can be reduced, and the amount of lubricant sealed in can be increased, resulting in a long-term lubrication effect.

[0014] The bearings described in Patent Documents 5 to 7 maintain a good lubrication environment and prevent material stripping inside the bearing by keeping the lubricant inside for a long time. However, in the future, it will be necessary to improve the reliability of the materials for the long-term use of bearings.

[0015] Axle bearings, which support the wheel axles (wheels and axles) of railway vehicles, function to support the weight of the vehicle and enable the wheels to rotate, and are subjected to high loads along with vibrations during operation. Therefore, the most concerning type of damage to axle bearings is peeling at the rolling contact points of the components that make up the bearing: the outer ring, the inner ring, and the rolling elements (rollers). Various factors can cause bearing peeling, but for railway vehicle bearings used in relatively well-lubricated environments, internal fatigue is a notable contributing factor. Therefore, to prevent peeling, high cleanliness of the materials used for the inner ring, outer ring, and rolling elements is crucial.

[0016] In the past, most railway vehicle axle bearings used carburized bearing steel (surface hardened steel) such as SNCM 420 as specified in JIS G 4052. In addition, in recent years, through the evolution of steelmaking methods, the cleanliness of high carbon chromium bearing steels such as SUJ2 as specified in JIS G 4805 has been confirmed to have improved quality.

[0017] Furthermore, as a prior art concerning the materials inside the bearing, for example, Patent Document 8 proposes a rolling bearing in which the inner ring is made of high-carbon chromium bearing steel, a specific carburized layer or carbonitrided layer is formed on the raceway surface, and the hardness and average residual austenite content of the core are specified. The rolling bearing described in Patent Document 8 exhibits excellent dimensional stability, is difficult to damage even under high fitting stress, and achieves a long service life.

[0018] In addition, the aforementioned patent document 7 also describes the materials, stating that the inner and outer rings of the bearing in the bearing unit are made of bearing steel or carburized steel.

[0019] Existing technical documents

[0020] Patent documents

[0021] Patent Document 1: Japanese Patent Application Publication No. 2009-210018

[0022] Patent Document 2: Japanese Patent No. 4260935

[0023] Patent Document 3: Japanese Patent No. 4731508

[0024] Patent Document 4: International Publication No. 2019 / 74042

[0025] Patent Document 5: Japanese Patent No. 4751808

[0026] Patent Document 6: Japanese Patent Application Publication No. 2016-8700

[0027] Patent Document 7: Japanese Patent Application Publication No. 2001-301617

[0028] Patent Document 8: Japanese Patent Application Publication No. 2006-71022 Summary of the Invention

[0029] The problem that the invention aims to solve

[0030] However, while the aforementioned axle bearings with sealing devices retain the functions of conventional bearings, they cannot adequately meet future demands such as improved maintainability, weight reduction, and space saving.

[0031] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a railway vehicle axle bearing that can achieve improved reliability and long service life, as well as lightweight and space-saving design.

[0032] Methods for solving problems

[0033] The above-mentioned objective of the present invention is achieved by the following structure.

[0034] A railway vehicle axle bearing includes: an outer ring; an inner ring; and a plurality of rolling elements, the plurality of rolling elements being rotatably disposed between the outer ring and the inner ring. The railway vehicle axle bearing supports the axle for rotational freedom, and a railway vehicle wheel is mounted at one end of the axle. The railway vehicle axle bearing comprises:

[0035] A sealing member, the sealing member being mounted on the outer ring and extending radially inward from the outer ring; and

[0036] A radial stepped portion of one or more levels, wherein the stepped portion is formed on the outer diameter portion of the inner ring adjacent to the inner diameter portion of the sealing member.

[0037] Two or more radial gaps are formed between the inner diameter portion of the sealing member and the outer diameter portion of the inner ring on which the stepped portion is formed.

[0038] Invention Effects

[0039] The railway vehicle axle bearing according to the present invention can improve reliability and extend service life, and also achieve lightweight and space-saving design. Attached Figure Description

[0040] Figure 1This is a schematic cross-sectional view showing a bearing unit for railway vehicles that includes the axle bearing for railway vehicles according to the first embodiment of the present invention.

[0041] Figure 2 It is an enlarged representation Figure 1 A schematic cross-sectional view of part A.

[0042] Figure 3 This is a schematic cross-sectional view showing a bearing unit for railway vehicles that includes the axle bearing for railway vehicles according to the second embodiment of the present invention.

[0043] Figure 4 It is an enlarged representation Figure 1 A schematic cross-sectional view of part B. Detailed Implementation

[0044] The following describes in detail, based on the accompanying drawings, the axle bearing for railway vehicles according to embodiments of the present invention.

[0045] (First Implementation)

[0046] Figure 1 This is a schematic cross-sectional view of a railway vehicle bearing unit 10 that includes a railway vehicle bearing according to the first embodiment of the present invention. Figure 2 It is an enlarged representation Figure 1 A schematic cross-sectional view of part A.

[0047] like Figure 1 As shown, the railway vehicle bearing unit 10 of this first embodiment includes multiple rows of tapered roller bearings 20 as axle bearings for railway vehicles, and the axle 50 of the railway vehicle is supported by these multiple rows of tapered roller bearings 20 to allow for free rotation. Furthermore, at the outer end of the axle 50 (i.e., Figure 1 The section with the increased axle diameter is fitted with a wheel (not shown) from a railway vehicle.

[0048] Furthermore, the multi-row tapered roller bearing 20 includes: a single outer ring 21; two inner rings 23, 23, each divided into rows; a plurality of tapered rollers (rolling elements) 22 that are freely disposed between the raceway surfaces of the outer ring 21 and the inner rings 23, 23; a retainer 24 for holding the plurality of tapered rollers 22; and an inner ring spacer 28 disposed between the inner rings 23, 23 to adjust the bearing clearance. In addition, a grease supply port (not shown) for sealing grease (lubricant) into the bearing space is formed at an appropriate position in the axial center of the outer ring 21.

[0049] At both axial ends of the inner rings 23, 23, the front cover 11 and the rear cover 27 are arranged around the axle 50 such that they abut against the axial end faces of the inner rings 23, ...

[0050] Additionally, the outer ring 21 is axially positioned by being fixed to a housing (not shown). Here, the width dimension W1 of the outer ring 21 is the same as the width dimension W2 of the two inner rings 23, 23.

[0051] In this first embodiment, high-carbon chromium bearing steel is used as the material for the outer ring 21, and carburized bearing steel is used as the material for the inner rings 23. Examples of high-carbon chromium bearing steel include symbols SUJ2, SUJ3, SUJ5 as described in JIS G 4805, and symbol 52100 as described in SAE J 404. Examples of carburized bearing steel include symbols SCr 415, SCr 420, SCM 420, SNCM 220, SNCM 815 as described in JIS G 4053, and symbols 5120, 8620, 4320 as described in SAE J 404.

[0052] Furthermore, sealing devices 29, 29 are provided on both sides of the multi-row tapered roller bearing 20 in this first embodiment, that is, at the axial ends of the axle 50, to prevent foreign objects from entering the multi-row tapered roller bearing 20 and to prevent lubricant (grease) from leaking out of the bearing.

[0053] like Figure 2 As shown, the sealing device 29 includes: a metal sealing member 30 mounted on and extending radially inward from the outer ring 21; and a first-order radially stepped portion 26 formed in the outer diameter portion (large flange) 25 of the inner ring 23, the outer diameter portion (large flange) 25 abutting an elastomer 35 forming the inner diameter portion of the sealing member 30. The stepped portion 26 is formed in the outer diameter portion 25 of the inner ring 23 on the end side in the width direction relative to the inner ring raceway surface 23a. Figure 2 (The right side of the middle).

[0054] The sealing member 30 is formed in a U-shaped cross section and has: an outer cylindrical portion 31, which is installed on the inner diameter portion 21b of the outer ring 21 at the end side in the width direction of the outer ring raceway surface 21a; a vertical plate portion 32, which extends radially inward from the outer end in the width direction of the outer cylindrical portion 31; and an inner cylindrical portion 33, which extends inward from the inner diameter end of the vertical plate portion 32 towards the inside of the bearing.

[0055] An elastic body 35 is integrally provided on the inner cylindrical portion 33. The elastic body 35 has a cylindrical protrusion 36 extending inward toward the bearing in a manner that reduces the radial clearance between the elastic body 35 and the outer peripheral surface 25a of the outer diameter portion 25, and a pair of annular protrusions 37 extending radially inward in a manner that reduces the radial clearance between the elastic body 35 and the outer peripheral surface 26a of the stepped portion 26. The elastic body 35 together with the inner cylindrical portion 33 forms the inner diameter portion of the sealing member 30.

[0056] Therefore, two levels (more than two) radial gaps 41, 42 are formed between the elastomer 35 forming the inner diameter portion of the sealing member 30 and the outer diameter portion 25 of the inner ring 23 with the stepped portion 26, forming a so-called labyrinth structure.

[0057] That is, the sealing device 29 in this first embodiment is a non-contact sealing device with two-stage radial gaps 41, 42 (labyrinth structure) formed by the outer diameter portion 25 of the inner ring 23 with the stepped portion 26 and the sealing member 30 installed on the inner diameter portion 21b of the outer ring 21.

[0058] In this way, by giving the inner side of the multi-row tapered roller bearing 20 a labyrinth-structured internal sealing function, the width dimension W1 of the outer ring 21 in the multi-row tapered roller bearing 20 can be the same as the width dimension W2 of the two inner rings 23, 23, making it easy to reduce the weight and save space of the multi-row tapered roller bearing 20. Furthermore, the multi-row tapered roller bearing 20 has a compact bearing size and can maintain internal sealing with a fewer number of parts.

[0059] Furthermore, by increasing the number of radially stepped portions 26 formed on the outer diameter portion 25 of the inner ring 23, and by making the inner diameter portion of the sealing member 30 adjacent to each stepped portion 26, a more complex labyrinth structure can be formed to improve the sealing performance.

[0060] Furthermore, in this first embodiment, the sealing member 30 is formed with a U-shaped cross-section extending inward from the inner diameter portion towards the bearing, creating a grease accumulation space 38 that is wider axially toward the inner side of the bearing. Therefore, it is easy to maintain the lubricity of the multi-row tapered roller bearing 20, and it is expected to help prevent grease leakage.

[0061] Furthermore, an elastomer 35 is integrally provided on the inner cylindrical portion 33 of the sealing member 30 in this first embodiment. The elastomer 35 has a cylindrical protrusion 36 and a pair of annular protrusions 37. Since the elastomer 35 is formed of an elastic sealing material, it will not be damaged even if the cylindrical protrusion 36 or the annular protrusion 37 comes into contact with the outer diameter portion 25 or the stepped portion 26 of the inner ring 23. Therefore, the radial gaps 41 and 42 can be minimized and the sealing performance can be improved.

[0062] Furthermore, the end of the inner cylindrical portion 33 in the sealing member 30 is positioned opposite the side wall surface 26b between the outer diameter portion 25 and the stepped portion 26 of the inner ring 23 in the axle direction. Therefore, when disassembling the sealing member 30 from the multi-row tapered roller bearing 20, the sealing member 30 can be easily separated from the outer ring 21 by pressing the inner cylindrical portion 33 of the sealing member 30 outward in the axle direction with the side wall surface 26b of the inner ring 23.

[0063] As explained above, the multi-row tapered roller bearing 20 according to this first embodiment can achieve improved reliability and longer service life, as well as lightweight and space-saving design.

[0064] Furthermore, in the multi-row tapered roller bearing 20 of this first embodiment, the outer ring 21 and the inner rings 23, 23 are formed of different materials. The effects of this structure will be explained in detail below.

[0065] Typically, in axle bearings, the bearing interior is not used under pressure but rather with clearance. Therefore, the likelihood of peeling occurring on the outer raceway surface is highest. In this first embodiment, the outer ring 21 is made of high-carbon chromium bearing steel, a material with high cleanliness, thus achieving a higher degree of suppression of internal initiation-type peeling.

[0066] Furthermore, the inner diameter surfaces of the inner rings 23, 23 typically contact the outer diameter surfaces of the axle 50 with a sufficient interference fit. When supporting a large vehicle weight, insufficient interference fit can lead to creep in the inner rings 23, 23. Therefore, setting a large interference fit is important to prevent this creep. In this first embodiment, the inner rings 23, 23 are made of carburized bearing steel, which generates compressive stress on its surface due to carburizing heat treatment. Therefore, by using carburized bearing steel, which exhibits compressive stress in the radial direction of the axle 50, as the material for the inner rings 23, 23, a high tolerance value for the interference fit can be set.

[0067] Thus, the multi-row tapered roller bearing 20 according to this first embodiment can suppress internal peeling and achieve high reliability over a long period of time.

[0068] Furthermore, as described above, if the materials inside the bearing are appropriately selected while maintaining a good lubrication environment, the bearing can be used for a long time with high reliability. In this first embodiment, the multi-row tapered roller bearing 20 has sealing devices 29, 29 installed at both ends in its axial direction, thus preventing foreign matter from entering the interior of the multi-row tapered roller bearing 20 and preventing lubricant from leaking out of the interior of the multi-row tapered roller bearing 20, thereby maintaining a good lubrication environment. As a result, the reliability of bearing operation can be further improved, and a long service life can be achieved.

[0069] (Second Implementation)

[0070] Figure 3 This is a schematic cross-sectional view showing a railway vehicle bearing unit 10A that includes a railway vehicle bearing according to the second embodiment of the present invention. Figure 4 It is an enlarged representation Figure 3 A schematic cross-sectional view of part B. Furthermore, for the multi-row tapered roller bearing 20A, which is a railway vehicle bearing according to this second embodiment, the same reference numerals are used for the same components as those in the multi-row tapered roller bearing 20 according to the first embodiment, and detailed descriptions are omitted.

[0071] like Figure 3 As shown, the railway vehicle bearing unit 10A of this second embodiment includes multiple rows of tapered roller bearings 20A as railway vehicle axle bearings, and uses these multiple rows of tapered roller bearings 20A to support the railway vehicle axle 50 so that it can rotate freely.

[0072] In this second embodiment, sealing devices 29A and 29A are provided on both sides of the multi-row tapered roller bearing 20A. These sealing devices 29A and 29A prevent foreign objects from entering the multi-row tapered roller bearing 20A and prevent grease from leaking out of the bearing.

[0073] like Figure 4 As shown, the sealing device 29A includes: a metal sealing member 30A mounted on and extending radially inward from the outer ring 21, and a first-order radial step 26 formed in the outer diameter portion (large flange) 25 of the inner ring 23 adjacent to the inner diameter portion of the sealing member 30A. This step 26 is formed in the outer diameter portion 25 of the inner ring 23 on the end side in the width direction relative to the inner ring raceway surface 23a. Figure 4 (The right side of the middle).

[0074] The sealing member 30A is formed in a U-shaped cross section and has: an outer cylindrical portion 31A, which is mounted on the inner diameter portion 21b of the outer ring 21, which is located on the side of the outer ring raceway surface 21a closer to the end in the width direction; a vertical plate portion 32A, which extends radially inward from the outer end of the outer cylindrical portion 31A in the width direction; and an inner cylindrical portion 33A, which extends from the inner diameter end of the vertical plate portion 32A toward the inside of the bearing in such a way as to reduce the radial clearance between it and the outer peripheral surface 25a of the outer diameter portion 25.

[0075] An annular protrusion 37A is integrally provided on the inner cylindrical portion 33A. The annular protrusion 37A protrudes radially inward in a manner that reduces the radial gap between itself and the outer peripheral surface 26a of the stepped portion 26. The annular protrusion 37A, together with the inner cylindrical portion 33A, forms the inner diameter portion of the sealing member 30A.

[0076] Therefore, two levels of radial gaps 41 and 42 are formed between the inner cylindrical portion 33A and the annular protrusion 37A forming the inner diameter portion of the sealing member 30 and the outer diameter portion 25 of the inner ring 23 where the step portion 26 is formed, thus forming a so-called labyrinth structure.

[0077] That is, the sealing device 29 in this second embodiment is a non-contact sealing device with two-stage radial gaps 41, 42 (labyrinth structure) formed by the outer diameter portion 25 of the inner ring 23 with the stepped portion 26 and the sealing member 30A installed on the inner diameter portion 21b of the outer ring 21.

[0078] Thus, by incorporating a labyrinth-structured internal sealing function into the inner side of the multi-row tapered roller bearing 20A, the width dimension W1 of the outer ring 21 in the multi-row tapered roller bearing 20A can be made the same as the width dimension W2 of the two inner rings 23, 23, facilitating the lightweighting and space-saving of the multi-row tapered roller bearing 20A. Furthermore, the multi-row tapered roller bearing 20A has a compact bearing size and can maintain internal sealing with a fewer number of components.

[0079] Furthermore, by increasing the number of radially stepped portions 26 formed on the outer diameter portion 25 of the inner ring 23, and by making the inner diameter portion of the sealing member 30 adjacent to each stepped portion 26, a more complex labyrinth structure can be formed to improve sealing performance.

[0080] Furthermore, in this second embodiment, the sealing member 30A is formed in a U-shaped cross-section with its inner diameter extending inward toward the bearing, defining a grease accumulation space 38 that is wider axially toward the inner side of the bearing. Therefore, it is easy to maintain the lubricity of the multi-row tapered roller bearing 20A, and it is expected to help prevent grease leakage.

[0081] Furthermore, the sealing component 30A in this second embodiment is integrally formed from the same material such as metal or resin, thereby reducing manufacturing costs.

[0082] Therefore, the multi-row tapered roller bearing 20A according to this second embodiment, like the multi-row tapered roller bearing 20 according to the first embodiment, can achieve improved reliability and longer service life, as well as lightweighting, space saving, and further cost reduction.

[0083] Furthermore, the annular protrusion 37A of the inner cylindrical portion 33A of the sealing member 30A is positioned opposite the side wall surface 26b between the outer diameter portion 25 and the stepped portion 26 of the inner ring 23 in the axle direction. Therefore, when disassembling the sealing member 30A from the multi-row tapered roller bearing 20A, the side wall surface 26b of the inner ring 23 is pressed outward in the axle direction against the annular protrusion 37A of the sealing member 30A, thereby allowing the sealing member 30A to be easily separated from the outer ring 21.

[0084] Furthermore, the present invention is not limited to the embodiments described above, and can be appropriately modified and improved. Moreover, the material, shape, size, quantity, and arrangement of the constituent elements in the above embodiments are arbitrary and not limited, as long as the present invention can be realized.

[0085] For example, in this embodiment, multi-row tapered roller bearings 20 and 20A are used as axle bearings for railway vehicles, but this is not a limitation and other types of rolling bearings may also be used.

[0086] Here, the features of the embodiments of the railway vehicle axle bearing of the present invention described above are briefly summarized and listed as follows [1] to [5].

[0087] [1] A railway vehicle axle bearing (multi-row tapered roller bearing 20, 20A), which has the following characteristics:

[0088] An outer ring (21); an inner ring (23); and a plurality of rolling elements (conical rollers 22) are arranged freely between the outer ring (21) and the inner ring (23). The axle (50) of the railway vehicle is supported by an axle bearing for rotational freedom. The axle (50) has wheels mounted at its ends.

[0089] The railway vehicle axle bearing has the following features:

[0090] A sealing member (30, 30A) is mounted on the outer ring (21) and extends radially inward from the outer ring (21); and

[0091] A radial step (26) formed at least one level in the outer diameter portion (25) of the inner ring (23) adjacent to the inner diameter portion of the sealing member (30, 30A).

[0092] Two or more radial gaps (41, 42) are formed between the inner diameter portion of the sealing member (30, 30A) and the outer diameter portion (25) of the inner ring (23) on which the stepped portion (26) is formed.

[0093] According to the structure described above [1], a labyrinth structure with two or more radial gaps (41, 42) is formed by the outer diameter portion (25) of the inner ring (23) with a stepped portion (26) and the sealing member (30) installed on the inner diameter portion (21b) of the outer ring (21).

[0094] Thus, by incorporating a labyrinth-structured internal sealing function into the inner side of the multi-row tapered roller bearings (20, 20A), it becomes easier to achieve lightweight and space-saving design. Furthermore, the multi-row tapered roller bearings (20, 20A) have a compact bearing size and can maintain internal sealing with a smaller number of components.

[0095] [2] According to the above [1], the axle bearings for railway vehicles (multi-row tapered roller bearings 20, 20A) are used.

[0096] The width dimension (W1) of the outer ring (21) is the same as the width dimension (W1) of the inner ring (23).

[0097] According to the structure described above [2], by making the width dimension (W1) of the outer ring (21) of the multi-row tapered roller bearing (20, 20A) the same as the width dimension (W2) of the two inner rings (23, 23), it becomes easy to make the multi-row tapered roller bearing (20, 20A) lightweight and space-saving.

[0098] [3] According to the railway vehicle axle bearings (multi-row tapered roller bearings 20, 20A) described in [1] or [2] above, wherein,

[0099] The sealing components (30, 30A) are formed in a U-shaped cross section and have: an outer cylindrical portion (31, 31A) which is mounted on the inner diameter portion (21b) of the outer ring (21); a vertical plate portion (32, 32A) which extends radially inward from the outer end of the outer cylindrical portion (31, 31A) in the width direction; and an inner cylindrical portion (33, 33A) which extends inward from the inner diameter end of the vertical plate portion (32, 32A) towards the bearing.

[0100] According to the structure described above [3], the sealing components (30, 30A) are formed in a U-shaped cross section, thereby creating a space (38) for grease accumulation that is wider in the axial direction toward the inside of the bearing. Therefore, it is easy to maintain the lubricity of the axle bearings (multi-row tapered roller bearings 20, 20A) for railway vehicles, and it is expected to help prevent grease leakage.

[0101] [4] According to the railway vehicle axle bearing (multi-row tapered roller bearing 20) described in [3] above, wherein,

[0102] An elastomer (35) is integrally provided on the inner cylindrical portion (33). The elastomer (35) has a cylindrical protrusion (36) extending toward the bearing in a manner that reduces the radial gap between the outer diameter portion (25) and an annular protrusion (37) extending radially inward in a manner that reduces the radial gap between the outer diameter portion (26).

[0103] According to the structure described above [4], the elastomer (35) formed by the elastic seal will not be damaged even if the cylindrical protrusion (36) or the annular protrusion (37) comes into contact with the outer diameter portion (25) or the stepped portion (26) of the inner ring (23), thus minimizing the radial clearance (41, 42) and improving the sealing performance.

[0104] [5] Railway vehicle axle bearings (multi-row tapered roller bearings 20, 20A) according to any one of [1] to [4] above, wherein,

[0105] The outer ring (21) is made of high carbon chromium bearing steel, and the inner ring (23) is made of carburized bearing steel.

[0106] According to the structure described above [5], the outer ring (21) is made of high-carbon chromium bearing steel, which is a high-cleanliness material, thus achieving a high effect in suppressing internal starting point-type peeling. In addition, the inner ring (23) is made of carburized bearing steel, which generates compressive stress on the surface through carburizing heat treatment. Therefore, by using carburized bearing steel, which has compressive stress in the radial direction of the axle (50), as the material of the inner ring (23), the allowable value of interference fit can be set high.

[0107] Thus, the railway vehicle axle bearings (multi-row tapered roller bearings 20, 20A) with the structure described above [5] can suppress internal peeling and achieve high reliability over a long period of time.

[0108] Furthermore, this application is based on Japanese Patent Application No. 2023-065068, filed on April 12, 2023, the contents of which are incorporated herein by reference.

[0109] Industrial applications

[0110] The railway vehicle axle bearing according to the present invention has the functions of conventional bearings and can fully meet future needs such as improved maintainability, lightweighting, and space saving.

[0111] Explanation of reference numerals in the attached figures:

[0112] 10. Bearing Units for Railway Vehicles

[0113] 20+ rows of tapered roller bearings (railway vehicle axle bearings)

[0114] 21 Outer ring

[0115] 22. Conical roller (rolling element)

[0116] 23 Inner Circle

[0117] 25 Outer diameter section

[0118] 26 Steps

[0119] 29 Sealing device

[0120] 41 Radial clearance

[0121] 50 axles

Claims

1. A type of axle bearing for railway vehicles, characterized in that, The railway vehicle axle bearing comprises: an outer ring; an inner ring; and a plurality of rolling elements, wherein the plurality of rolling elements are rotatably disposed between the outer ring and the inner ring. The axle bearing supports the axle for free rotation, and the axle has a wheel of the railway vehicle mounted at its end. The railway vehicle axle bearing has the following features: A sealing member, the sealing member being mounted on the outer ring and extending radially inward from the outer ring; and A radial stepped portion of one or more levels, wherein the stepped portion is formed on the outer diameter portion of the inner ring adjacent to the inner diameter portion of the sealing member. Two or more radial gaps are formed between the inner diameter portion of the sealing member and the outer diameter portion of the inner ring on which the stepped portion is formed.

2. The axle bearing for railway vehicles according to claim 1, characterized in that, The width of the outer ring is the same as the width of the inner ring.

3. The railway vehicle axle bearing according to claim 1 or 2, characterized in that, The sealing component is formed in a U-shape with an outer cylindrical portion, a vertical plate portion, and an inner cylindrical portion. The outer cylindrical portion is installed on the inner diameter portion of the outer ring. The vertical plate portion extends radially inward from the outer end of the outer cylindrical portion in the width direction. The inner cylindrical portion extends inward from the inner diameter end of the vertical plate portion towards the bearing.

4. The axle bearing for railway vehicles according to claim 3, characterized in that, An elastic body is integrally provided on the inner cylindrical portion. The elastic body has a cylindrical protrusion extending toward the bearing in a manner that reduces the radial clearance between itself and the outer diameter portion, and an annular protrusion extending radially inward in a manner that reduces the radial clearance between itself and the stepped portion.

5. The railway vehicle axle bearing according to any one of claims 1 to 4, characterized in that, The outer ring is made of high-carbon chromium bearing steel. The inner ring is made of carburized bearing steel.

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