Axle bearing for railway vehicle

Abstract

The multi-row tapered roller bearing (20) has an outer ring (21), an inner ring (23), and a plurality of tapered rollers (22) arranged between the outer ring and the inner ring so as to be capable of rolling, and rotatably supports an axle (50) of a railway vehicle, the multi-row tapered roller bearing (20) being provided with: an outer seal member (30) for sealing the outer ring (21) and the inner ring (23); the outer ring (21) is provided with an outer cylinder part (31) which is arranged on an inner diameter part (21b) of the outer ring (21) and a vertical plate part (32) which extends from the width direction outer end of the outer cylinder part to the radial inner side; a small-diameter stepped section (26) formed on an outer-diameter section (25) of the inner ring (23) adjacent to an inner-diameter end (32a) of the standing plate section; and an elastic body (35) that is fixed to the inner diameter end (32a) of the standing plate section (32) and faces the outer periphery of the small-diameter stepped section (26). The inner diameter end (32a) of the standing plate portion (32) adjacent to the outer periphery of the small-diameter step portion faces a side wall surface (26b) between the outer diameter portion (25) of the inner ring and the small-diameter step portion (26) in the axle direction.

Description

Technical Field

[0001] This invention relates to a railway vehicle axle bearing that supports the axle of a railway vehicle in a rotatable manner. 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"), an example of a railway vehicle axle bearing, on which the railway vehicle axle is supported. The bearing has a single outer ring and two inner rings, each divided into rows, with multiple tapered rollers rolled freely between the two rows of raceway surfaces of the outer and inner rings and held in a retainer. 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 maintenance, 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 demand for longer maintenance cycles and reduced maintenance for railway vehicles. 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 in which grease is sealed inside the bearing and has a sealing device for retaining the grease.

[0006] Patent Document 1 discloses a sealing device in which, to improve disintegration, a notch for inserting a disintegration tool is provided on the outer diameter of the sealing housing. This sealing device forms a contact seal between the sealing components fixed to both axial ends of the outer ring and the 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 pulling by hand or 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 mounted 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 position. 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 bearings to be used for a longer period of time.

[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 outer ring, inner ring, and 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, it is crucial that the materials of the inner ring, outer ring, and rolling elements maintain a high level of cleanliness.

[0016] In the past, carburized bearing steels such as SNCM 420 (surface hardened steel) specified in JIS G 4052 were widely used in railway vehicle axle bearings. Furthermore, in recent years, advancements in steelmaking methods have led to improvements in the cleanliness and quality of high-carbon chromium bearing steels such as SUJ2 specified in JIS G 4805.

[0017] Furthermore, as a prior art concerning the materials inside the bearing, for example, Patent Document 8 discloses a rolling bearing in which the inner ring is made of high-carbon chromium bearing steel, a specific carburized layer or carburized nitrided layer is formed on the raceway surface, and the hardness and average amount of retained austenite in the core are specified. The rolling bearing described in Patent Document 8 exhibits excellent dimensional stability, is difficult to damage even under high mating stress, and can achieve 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 technical problem that the invention aims to solve

[0030] However, in the sealing device of Patent Document 1, it is difficult to make the width of the outer diameter of the sealing housing less than or equal to the width of the outer ring or the inner ring for the purpose of compactness. Furthermore, in the bearing device for railway vehicles of Patent Document 2, the width of the sealing outer ring of the sealing member is greater than the width of the inner ring, and compactness is not considered.

[0031] Furthermore, in the multi-row tapered roller bearing of Patent Document 3, disassembly is not considered, there is no part for inserting a disassembly tool during seal disassembly, and it is difficult to disassemble simultaneously with the inner ring. In addition, in the sealing device of Patent Document 4, since a guide part (recess, protrusion, threaded hole, etc.) for inserting the disassembly tool is provided, there is a problem that the shape of the disassembly tool is complex and subject to size constraints.

[0032] Therefore, 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.

[0033] 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 improve reliability and extend service life while also improving maintainability, reducing weight and saving space.

[0034] Technical means for solving problems

[0035] The above-mentioned objective of the present invention is achieved by the following structure.

[0036] 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 provides a rotatable support for an axle on which a wheel of a railway vehicle is mounted at its end. The railway vehicle axle bearing comprises:

[0037] An outer sealing member having an outer cylindrical portion mounted on the inner diameter portion of the outer ring and a vertical plate portion extending radially inward from the outer end of the outer cylindrical portion in the width direction;

[0038] A stepped portion of one or more minor diameters, wherein the stepped portion is formed on the outer diameter portion of the inner ring adjacent to the inner diameter end of the upright plate; and

[0039] An elastomer is fixed to the inner diameter end of the upright plate and faces the outer periphery of the small-diameter stepped portion.

[0040] The inner diameter end of the upright plate portion adjacent to the outer periphery of the small diameter step portion is opposite to the side wall surface located between the outer diameter portion of the inner ring and the small diameter step portion in the axle direction.

[0041] Invention Effects

[0042] The railway vehicle axle bearing according to the present invention can achieve improved reliability and longer service life, as well as improved maintainability, lightweight design, and space saving. Attached Figure Description

[0043] Figure 1 This is a schematic cross-sectional view showing a bearing unit for railway vehicles, including the axle bearing for railway vehicles according to the first embodiment of the present invention.

[0044] Figure 2 It is an enlarged representation Figure 1 A schematic cross-sectional view of part A.

[0045] Figure 3 This is an explanation Figure 1 A schematic cross-sectional view showing the disassembly steps of a railway vehicle axle bearing.

[0046] Figure 4 This is a schematic cross-sectional view showing a bearing unit for railway vehicles, including the axle bearing for railway vehicles according to the second embodiment of the present invention.

[0047] Figure 5 It is an enlarged representation Figure 4 A schematic cross-sectional view of part B. Detailed Implementation

[0048] The following describes in detail, based on the accompanying drawings, the axle bearing for railway vehicles according to embodiments of the present invention.

[0049] (First Implementation)

[0050] Figure 1 This is a schematic cross-sectional view showing a railway vehicle bearing unit 10 including the railway vehicle bearing of the first embodiment of the present invention. Figure 2 It is an enlarged representation Figure 1 A schematic cross-sectional view of part A.

[0051] like Figure 1As 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, which support the axle 50 of the railway vehicle 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.

[0052] 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.

[0053] 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 respectively. Moreover, the inner rings 23, 23 and the rear cover 27 are sandwiched between the outer peripheral step portion 51 of the axle 50 and the front cover 11, and are fixed from the axle end 52 side of the axle 50 by bolts 13.

[0054] In addition, the outer ring 21 is positioned axially by being fixed to a housing (not shown).

[0055] 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 SUJ2, SUJ3, SUJ5 as described in JIS G 4805, and 52100 as described in SAE J 404. Examples of carburized bearing steel include SCr 415, SCr 420, SCM 420, SNCM 220, SNCM 815 as described in JIS G 4053, and 5120, 8620, 4320 as described in SAE J 404.

[0056] 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.

[0057] like Figure 2As shown, the sealing device 29 comprises an outer sealing member 30 mounted on the outer ring 21, a first-stage small-diameter step portion 26 formed in the outer diameter portion (large flange) 25 of the inner ring 23 adjacent to the inner diameter portion of the outer sealing member 30, and an inner sealing member 40 fixed to the small-diameter step portion 26. The small-diameter step 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).

[0058] The outer sealing member 30 is formed of metal in an L-shaped cross-section having an outer cylindrical portion 31 and a vertical plate portion 32. The outer cylindrical portion 31 is mounted on the inner diameter portion 21b of the outer ring 21, which is located on the side closer to the outer ring raceway surface 21a in the width direction. The vertical plate portion 32 extends radially inward from the outer end of the outer cylindrical portion 31 in the width direction. The inner diameter end 32a of the vertical plate portion 32 is positioned relative to the side wall surface 26b between the outer diameter portion 25 and the small diameter stepped portion 26 of the inner ring 23 in the axle direction ( Figure 2 (The left and right directions in the middle) are opposite each other.

[0059] Therefore, the outer sealing member 30, which is formed with an L-shaped cross section, has the following simple and compact shape: the vertical plate portion 32, which extends radially inward from the outer end of the outer cylindrical portion 31 mounted on the inner circumferential surface of the inner diameter portion 21b of the outer ring 21, does not extend beyond the outer ring end face of the outer ring 21.

[0060] An elastic body 35 is integrally provided and fixed at the inner diameter end 32a of the outer sealing member 30, which is opposed to the outer periphery of the small diameter stepped portion 26 of the inner ring 23. The elastic body 35 together with the inner diameter end 32a of the upright plate portion 32 forms the inner diameter portion of the outer sealing member 30.

[0061] The elastomer 35, formed from an elastic sealant such as rubber or an elastomer, integrally comprises a first lip 36, a second lip 37, a third lip 38, and a fourth lip 39 that are in slidable contact with the inner sealing member 40 fixed to the small-diameter step portion 26.

[0062] The inner sealing member 40 is formed in the shape of a U-shaped cross section having an inner sleeve 41, a flange 42 and an outer sleeve 43, wherein the inner sleeve 41 is pressed into the small diameter step portion 26 of the inner ring 23, the flange 42 extends radially outward from the outer end of the inner sleeve 41 in the width direction, and the outer sleeve 43 extends inward from the inner diameter end of the flange 42 towards the inside of the bearing.

[0063] The first lip 36 of the elastomer 35 is in slidable contact with the outer peripheral surface of the inner sleeve 41 in the inner sealing member 40 around the entire circumference, mainly to prevent or reduce the leakage of grease from the inside of the bearing to the atmosphere.

[0064] The second lip 37 of the elastomer 35 is slidably in contact with the outer peripheral surface of the inner sleeve 41 in the inner sealing member 40 around the entire circumference, mainly to prevent or reduce the intrusion of foreign matter from the atmospheric side into the inner side of the bearing.

[0065] Furthermore, by providing an inner sealing member 40 that can slide in contact with the elastomer 35 on the outer peripheral surface 26a of the small-diameter stepped portion 26 of the inner ring 23, wear on the outer peripheral surface 26a of the small-diameter stepped portion 26 due to sliding contact with the elastomer 35 is prevented. Moreover, when the sealing function is reduced, the initial sealing performance can be restored by simply replacing the inner sealing member 40.

[0066] In addition, the third lip 38 and the fourth lip 39 of the elastomer 35 are configured to radially sandwich the outer sleeve 43 of the inner sealing member 40, forming a labyrinth seal.

[0067] Moreover, such as Figure 2 As shown, the multi-row tapered roller bearing 20 of this first embodiment is configured such that the axial relative distance L1 between the outer surface 24a of the retainer 24 and the upright plate portion 32 of the outer sealing member 30 is greater than the axial relative distance L2 between the side wall surface 26b located between the outer diameter portion 25 and the small diameter step portion 26 of the inner ring 23 and the upright plate portion 32 of the outer sealing member 30. The retainer 24 holds the plurality of tapered rollers 22 so that they can rotate freely.

[0068] Thus, according to the multi-row tapered roller bearing 20 of the first embodiment described above, when disassembling the sealing device 29, the sidewall surface 26b of the inner ring 23, which moves axially relative to the outer ring 21, presses against the inner diameter end 32a of the outer sealing member 30, thereby enabling the outer sealing member 30 to be separated from the outer ring 21. That is, by employing a structure in which the inner ring 23 directly presses against the outer sealing member 30 of the sealing device 29, the disassembly of the sealing device 29 can be improved. As a result, the maintainability of the multi-row tapered roller bearing 20 is improved.

[0069] Here, an example of a method for disassembling a multi-row tapered roller bearing 20 is described.

[0070] Figure 3 This is an explanation Figure 1 A schematic cross-sectional view showing the exploded sequence of the multi-row tapered roller bearing 20.

[0071] like Figure 3 As shown, for example, when disassembling the sealing device 29 of the multi-row tapered roller bearing 20, the multi-row tapered roller bearing 20 is first placed on a fixture table 80 with one axial end of the multi-row tapered roller bearing 20 facing downwards. The fixture table 80 is formed as an annular shape having an outer diameter slightly larger than the outer diameter of the outer ring 21 and an inner diameter slightly larger than the inner diameter of the inner diameter portion 21b of the outer ring 21.

[0072] The disassembly tool 70 has: a drive shaft 71 that is driven up and down; a disc-shaped tool body 73 that is mounted at the lower end of the drive shaft 71; and a plurality of pressing plates 75 that are housed in the tool body 73 and whose ends extend and retract radially from the outer peripheral surface of the tool body 73.

[0073] The tool body 73 has an outer diameter slightly smaller than the inner diameter of the inner ring 23. Therefore, with the ends of the plurality of pressing tabs 75 completely submerged within the tool body 73, the tool body 73 can be inserted into the inner ring 23. Conversely, with the ends of the plurality of pressing tabs 75 protruding radially from the outer peripheral surface of the tool body 73, the ends of the pressing tabs 75 abut against the axial end of the inner ring 23, preventing the tool body 73 from being inserted into the inner ring 23.

[0074] Furthermore, the multi-row tapered roller bearing 20 is placed on the fixture table 80 with one axial end of the outer ring 21 facing the upper edge of the fixture table 80. At this time, the multi-row tapered roller bearing 20 placed on the fixture table 80 is pre-separated axially between the two inner rings 23, 23 so that the pressing piece 75 of the disassembly tool 70 can be inserted between the two inner rings 23, 23.

[0075] Next, the drive shaft 71 of the disassembly tool 70 is driven downwards, and the tool body 73, with the ends of the multiple pressing pieces 75 all submerged within it, is inserted into the upper inner ring 23. (As follows) Figure 3 As shown, the ends of multiple pressing tabs 75 protrude radially from the outer peripheral surface of the tool body 73, which passes through the upper inner ring 23, and are arranged between the two inner rings 23, 23. Therefore, the ends of the multiple pressing tabs 75 of the disassembly tool 70 abut against the inner ring spacer 28, which can press the axial end of the lower inner ring 23 downward.

[0076] Furthermore, if the drive shaft 71 of the disassembly tool 70 is driven further downward, the inner ring 23, which moves downward relative to the outer ring 21 supported on the fixture table 80, can separate the outer sealing member 30 from the outer ring 21 because the inner diameter end 32a of the outer sealing member 30 is pressed downward by the side wall surface 26b.

[0077] At this time, as described above, the axial relative distance L1 between the retainer 24 and the outer sealing member 30 is greater than the axial relative distance L2 between the inner ring 23 and the outer sealing member 30. Therefore, when the lower inner ring 23 is moved axially downward relative to the outer ring 21, the outer sealing member 30 will not contact the retainer 24 inside the bearing before contacting the side wall surface 26b of the inner ring 23.

[0078] That is, when the lower inner ring 23 moves axially downward relative to the outer ring 21, there is no need to worry about the outer sealing member 30 contacting the retainer 24, or the retainer 24 being damaged or deformed, which would render the multi-row tapered roller bearing 20 unusable. In particular, in retainers made of resin material, contact with the outer sealing member 30 must be avoided, therefore the structure of the multi-row tapered roller bearing 20 of this first embodiment is effective.

[0079] Furthermore, the outer sealing member 30, the inner sealing member 40, and the inner ring 23 constituting the sealing device 29 of this first embodiment can be constructed with a simple shape having the same cross-section in the circumferential direction. In addition, compared with the existing structure, the sealing device 29 of the multi-row tapered roller bearing 20 has a simple and compact shape, which can save space in the housing shape of fixing the outer ring 21 or omit the components. Therefore, it is possible to achieve a lightweight design for the bearing unit 10 for railway vehicles.

[0080] 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 improved maintainability, weight reduction, and space saving.

[0081] 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.

[0082] Typically, axle bearings are used with clearance, not under internal pressure. 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 better effect in suppressing internal starting-point peeling.

[0083] Furthermore, the inner diameter surfaces of the inner rings 23, 23 typically have sufficient interference fit with the outer diameter surfaces of the axle 50. 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 undergoes carburizing heat treatment to generate compressive stress on its surface. 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 for interference fit can be achieved.

[0084] 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.

[0085] Furthermore, as described above, if the materials inside the bearing are appropriately selected while maintaining a relatively good lubrication environment, the bearing can be used for a long period 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 multi-row tapered roller bearing 20 and preventing lubricant from leaking out 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.

[0086] (Second Implementation)

[0087] Figure 4 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 5 It is an enlarged representation Figure 4 A schematic cross-sectional view of part B. Furthermore, in the multi-row tapered roller bearing 20A for railway vehicles 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.

[0088] like Figure 4 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 the multiple rows of tapered roller bearings 20A support the railway vehicle axle 50 so that it can rotate freely.

[0089] 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.

[0090] like Figure 5 As shown, the sealing device 29A comprises an outer sealing member 30A mounted on the outer ring 21, a first-stage small-diameter step portion 26 formed in the outer diameter portion (large flange) 25 of the inner ring 23 adjacent to the inner diameter portion of the outer sealing member 30A, and an inner sealing member 40 fixed to the small-diameter step portion 26. The small-diameter step 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 5 (The right side of the middle).

[0091] The outer sealing member 30A is formed of metal and has a U-shaped cross-section, and includes: an outer cylindrical portion 31, which is mounted on the inner diameter portion 21b of the outer ring 21 at its width-direction end side relative to the raceway surface 21a of the outer ring; a vertical plate portion 32, which extends radially inward from the outer end of the outer cylindrical portion 31 in the width direction; and an inner cylindrical portion 33, which extends inward from the inner diameter end 32a of the vertical plate portion 32 towards the bearing. The end of the inner cylindrical portion 33 of the vertical plate portion 32 is located relative to the side wall surface 26b between the outer diameter portion 25 and the small diameter stepped portion 26 of the inner ring 23 in the axle direction ( Figure 5 (The left and right directions in the middle) are opposite each other.

[0092] Therefore, the outer sealing member 30A, which is formed in the shape of a U-shaped cross section, has a simple and compact shape, wherein the vertical plate portion 32, which extends radially inward from the outer end of the outer cylindrical portion 31 mounted on the inner circumferential surface of the inner diameter portion 21b of the outer ring 21, does not extend beyond the outer ring end face of the outer ring 21.

[0093] An elastomer 35A is integrally provided and fixed to the inner diameter end 32a of the upright plate portion 32 and the inner cylindrical portion 33 of the outer sealing member 30A. The elastomer 35A and the inner cylindrical portion 33 together form the inner diameter portion of the outer sealing member 30A.

[0094] The elastomer 35A, formed from an elastic sealant such as rubber or an elastomer, integrally has a first lip 36, a second lip 37, a third lip 38, and a fourth lip 39 that are in slidable contact with the inner sealing member 40 fixed to the small-diameter step portion 26.

[0095] Moreover, such as Figure 5 As shown, the multi-row tapered roller bearing 20A of this second embodiment is configured such that the axial relative distance L1 between the outer surface 24a of the retainer 24 and the upright plate portion 32 of the outer sealing member 30A is greater than the axial relative distance L2 between the side wall surface 26b and the upright plate portion 32 of the outer sealing member 30A. The retainer 24 holds the plurality of tapered rollers 22 so that they can rotate freely. The side wall surface 26b is located between the outer diameter portion 25 of the inner ring 23 and the small diameter stepped portion 26.

[0096] Thus, according to the multi-row tapered roller bearing 20A of the second embodiment described above, similarly to the multi-row tapered roller bearing 20 of the first embodiment, when disassembling the sealing device 29A, the sidewall surface 26b of the inner ring 23, which moves axially relative to the outer ring 21, presses against the inner cylindrical portion 33 of the outer sealing member 30A, thereby enabling the outer sealing member 30A to separate from the outer ring 21. That is, by employing a structure where the inner ring 23 directly presses against the outer sealing member 30A of the sealing device 29A, the disassembly capability of the sealing device 29A can be improved. As a result, the maintainability of the multi-row tapered roller bearing 20A is improved.

[0097] Furthermore, the outer sealing member 30A constituting the sealing device 29A of this second embodiment can be constructed with a simple shape having the same cross-section in the circumferential direction. In addition, compared with the existing structure, the sealing device 29A of the multi-row tapered roller bearing 20A has a simple and compact shape, which can save space in the housing shape of the fixed outer ring 21 or omit the constituent parts. Therefore, it is possible to achieve a lightweight bearing unit 10A for railway vehicles.

[0098] Furthermore, in this second embodiment, the outer sealing member 30A is formed into a U-shaped cross-section extending inward from its inner diameter portion toward the bearing, defining a space 15 for a grease accumulation portion that widens axially toward the bearing's inner side. 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.

[0099] However, since railway vehicle axle bearings are used in a vibrating environment, it is necessary to ensure sufficient fitting allowance between the outer sealing component 30A and the outer ring 21. Therefore, the annular rigidity of the outer sealing component 30A, which contacts the side wall surface 26b of the inner ring 23, is important.

[0100] In this second embodiment, the outer sealing member 30A is formed into a U-shaped cross-section extending from its inner diameter towards the inside of the bearing. Compared to the L-shaped cross-section of the outer sealing member 30 in the first embodiment, its annular rigidity is higher. Therefore, the outer sealing member 30A is not easily deformed even under the force of being pressed by the side wall surface 26b of the inner ring 23, and is easy to disassemble.

[0101] As explained above, the multi-row tapered roller bearing 20A according to this second embodiment can achieve improved reliability and longer service life, as well as improved maintainability, weight reduction, and space saving.

[0102] 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 they enable the realization of the present invention.

[0103] 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.

[0104] Furthermore, in the above embodiment, the elastomer 35 (35A) opposite to the outer periphery of the small-diameter stepped portion 26 of the inner ring 23 has a first lip 36 and a second lip 37 that can slidably contact the inner sleeve 41 of the inner sealing member 40. The elastomer of the present invention is not limited to this, and can also be configured as an elastomer constituting a labyrinth seal, wherein the lip of the labyrinth seal opposite to the outer periphery of the small-diameter stepped portion does not contact the small-diameter stepped portion or the outer periphery of the inner sealing member.

[0105] 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].

[0106] [1] A railway vehicle axle bearing (multi-row tapered roller bearing 20, 20A) has an outer ring (21), an inner ring (23), and a plurality of rolling elements (tapered rollers 22) rotatably disposed between the outer ring (21) and the inner ring (23), and supports an axle (50) on which a railway vehicle wheel is mounted at the end for rotational freedom, wherein,

[0107] The railway vehicle axle bearings (multi-row tapered roller bearings 20 and 20A) include:

[0108] The outer sealing member (30, 30A) has an outer cylindrical portion (31) installed on the inner diameter portion (21b) of the outer ring (21) and a vertical plate portion (32) extending radially inward from the outer end of the outer cylindrical portion (31) in the width direction.

[0109] A stepped portion (26) of one or more minor diameters is formed on the outer diameter portion (25) of the inner ring (23) adjacent to the inner diameter end (32a) of the upright plate portion (32); and

[0110] An elastomer (35, 35A) is fixed to the inner diameter end (32a) of the upright plate portion (32) and faces the outer periphery of the small diameter stepped portion (26).

[0111] The inner diameter end (32a) of the upright plate portion (32) adjacent to the outer periphery of the small diameter step portion (26) is opposite to the side wall surface (26b) between the outer diameter portion (25) of the inner ring (23) and the small diameter step portion (26) in the axle direction.

[0112] According to the structure described above [1], when disassembling the outer sealing components (30, 30A), the side wall surface (26b) of the inner ring (23), which moves axially relative to the outer ring (21), presses against the inner diameter end (32a) of the outer sealing components (30, 30A), thereby enabling the outer sealing components (30, 30A) to separate from the outer ring (21). That is, by setting a structure in which the inner ring (23) directly presses against the outer sealing components (30, 30A), the disassembly capability of the sealing device can be improved. As a result, the maintainability of the axle bearings (multi-row tapered roller bearings 20, 20A) for railway vehicles is improved.

[0113] Furthermore, the outer sealing components (30, 30A) and the inner ring (23) can be constructed from simple shapes with the same cross-section in the circumferential direction. In addition, compared with the existing structure, the sealing device has a simple and compact shape, which can save space in the shape of the shell that fixes the outer ring (21) or omit the constituent parts, thus achieving the weight reduction of the bearing unit for railway vehicles.

[0114] [2] According to the railway vehicle axle bearings (multi-row tapered roller bearings 20, 20A) described in [1] above, wherein,

[0115] The axial relative distance (L1) between the retainer (24) and the outer sealing member (30, 30A) is greater than the axial relative distance (L2) between the side wall surface (26b) and the outer sealing member (30, 30A). The retainer (24) holds the plurality of rolling elements (conical rollers 22) to rotate freely. The side wall surface (26b) is located between the outer diameter portion (25) of the inner ring (23) and the small diameter step portion (26).

[0116] According to the structure described above [2], when the inner ring (23) moves axially relative to the outer ring (21), the outer sealing components (30, 30A) will not come into contact with the retainer (24) inside the bearing before contacting the side wall surface (26b) of the inner ring (23). Therefore, there is no need to worry about damage or deformation of the retainer 24 causing the multi-row tapered roller bearings (20, 20A) to become unusable.

[0117] [3] The axle bearings for railway vehicles (multi-row tapered roller bearings 20, 20A) as described in [1] or [2] above.

[0118] An inner sealing member (40) capable of sliding contact with the elastomer (35, 35A) is provided on the outer peripheral surface (26a) of the small diameter step portion (26).

[0119] According to the structure described above [3], wear on the outer peripheral surface (26a) of the small-diameter step portion (26) can be prevented due to the sliding contact of the elastomers (35, 35A). When the sealing function is reduced, the initial sealing performance can be restored by replacing only the inner sealing component (40).

[0120] [4] The axle bearing for railway vehicles (multi-row tapered roller bearing 20A) as described in [3] above.

[0121] The outer sealing member (30A) is formed with a U-shaped cross section of an inner cylindrical portion (33) extending from the inner diameter end (32a) of the vertical plate portion (32) toward the inside of the bearing.

[0122] According to the structure described above [4], the ring rigidity of the outer sealing component (30A) is improved, and it is not easy to be deformed by the force of the inner ring (23) side wall surface (26b), making it easy to carry out appropriate disassembly operations.

[0123] [5] Railway vehicle axle bearings (multi-row tapered roller bearings 20, 20A) according to any one of [1] to [4] above, wherein,

[0124] The outer ring (21) is made of high-carbon chromium bearing steel.

[0125] The inner ring (23) is made of carburized bearing steel.

[0126] 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 good effect in suppressing internal starting point-type peeling. In addition, the inner ring 23 is made of carburized bearing steel, which generates compressive stress in the surface layer by 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), it is possible to set a higher tolerance value for interference fit.

[0127] 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.

[0128] Furthermore, this application is based on Japanese Patent Application No. 2023-065069, filed on April 12, 2023, the contents of which are incorporated herein by reference.

[0129] Industrial practicality

[0130] The railway vehicle axle bearing of the present invention can fully meet future needs such as improved maintainability, lightweight design, and space saving while retaining the functions of conventional bearings.

[0131] Explanation of reference numerals in the attached figures

[0132] 10. Bearing Units for Railway Vehicles

[0133] 20+ rows of tapered roller bearings (railway vehicle axle bearings)

[0134] 21 Outer ring

[0135] 21b Inner diameter section

[0136] 22. Conical roller (rolling element)

[0137] 23 Inner Circle

[0138] 25 Outer diameter section

[0139] 26. Path Steps

[0140] 26b Sidewall

[0141] 29 Sealing device

[0142] 30 External sealing components

[0143] 31 Outer cylindrical section

[0144] 32 Vertical board part

[0145] 32a Inner Diameter End

[0146] 50 axles

Claims

1. A type of axle bearing for railway vehicles, characterized in that, The railway vehicle axle bearing includes: an outer ring; an inner ring; and a plurality of rolling elements, which are freely rotatably arranged between the outer ring and the inner ring. The railway vehicle axle bearing provides rotatable support for the axle on which the wheels of the railway vehicle are mounted. The railway vehicle axle bearing has the following features: An outer sealing member having an outer cylindrical portion mounted on the inner diameter portion of the outer ring and a vertical plate portion extending radially inward from the outer end of the outer cylindrical portion in the width direction; A stepped portion of one or more minor diameters, wherein the stepped portion is formed on the outer diameter portion of the inner ring adjacent to the inner diameter end of the upright plate; and An elastomer is fixed to the inner diameter end of the upright plate and faces the outer periphery of the small-diameter stepped portion. The inner diameter end of the upright plate portion adjacent to the outer periphery of the small diameter step portion is opposite to the side wall surface located between the outer diameter portion of the inner ring and the small diameter step portion in the axle direction.

2. The axle bearing for railway vehicles according to claim 1, wherein, The axial relative distance between the retainer that holds the multiple rolling elements in a rotatable manner and the outer sealing member is greater than the axial relative distance between the sidewall and the outer sealing member, wherein the sidewall is located between the outer diameter portion of the inner ring and the small diameter step portion.

3. The axle bearing for railway vehicles according to claim 1 or 2, wherein, An inner sealing component capable of sliding contact with the elastomer is provided on the outer periphery of the small-diameter stepped portion.

4. The axle bearing for railway vehicles according to claim 3, wherein, The outer sealing member is formed in the shape of a U-shaped cross section having an inner cylindrical portion extending from the inner diameter end of the vertical plate portion toward the inner side of the bearing.

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

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