Sealing structure for rail transit axle box bearing and axle box bearing

Abstract

The invention discloses a sealing structure for a rail transit axle box bearing and the axle box bearing. The sealing structure comprises a first framework, a second framework, a third framework, a first sealing lip and a second sealing lip. The outer side of the first framework is in interference fit with the bearing outer ring, the third framework is in interference fit with the bearing inner ring, and the second framework is installed on the inner side of the first framework in an interference fit mode. A sealing channel is arranged between the second framework and the third framework, and the first sealing lip abuts against the inner side of the third framework. A labyrinth seal is arranged between the first framework and the third framework, and the second sealing lip abuts against the inner side of the first framework. A sealing cavity is formed among the first framework, the second framework, the first sealing lip, the third framework and the second sealing lip. The four sealing structures can effectively prevent a lubricating medium in the bearing from leaking out and prevent external dust and water from entering, and after the running temperature of the bearing is increased, the lubricating medium enters the sealing cavity; tests prove that the sealing structure has good sealing performance, so that the service life of the bearing is prolonged, and the reliability of the bearing is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transit bearings, and in particular to a sealing structure for a rail transit axle box bearing and an axle box bearing. Background Art

[0002] The sealing assembly is an important component to ensure the performance of the axle box bearing. It can ensure the sealing performance of the bearing without affecting the operation of the bearing, block foreign matter such as dust and water from entering the bearing body, causing the grease to fail and reduce the lubrication performance, and also prevent the lubrication medium from leaking.

[0003] In traditional technology, the sealing cover structure is mainly formed by simple steel plate stamping, and non-contact sealing is adopted to block lubrication through a narrow channel without hindering the rotation of the bearing, such as Figure 1 As shown, the sealing performance of this type of non-contact sealing structure is poor, and the corresponding maintenance-free period of the bearing is short. Summary of the invention

[0004] The present invention provides a sealing structure for a rail transit axle box bearing and an axle box bearing to solve the above problems.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] A sealing structure for a rail transit axle box bearing and an axle box bearing, comprising a first frame, a second frame, a third frame, a first sealing lip and a second sealing lip;

[0007] The outer side of the first skeleton is interference fit with the outer ring of the bearing, the third skeleton is interference fit with the inner ring of the bearing, and the second skeleton is interference installed on the inner side of the first skeleton;

[0008] A sealing channel is provided between the second frame and the third frame along the axial direction, the first sealing lip is provided on the inner side of the second frame, and the first sealing lip abuts against the inner side of the third frame;

[0009] A labyrinth seal is provided between the first frame and the third frame, the second sealing lip is provided on the inner side of the third frame, and the second sealing lip abuts against the inner side of the first frame;

[0010] A sealing cavity is formed between the first frame and the second frame, the first sealing lip, the third frame and the second sealing lip.

[0011] Further, the first skeleton includes a first extension section extending in the axial direction, and the third skeleton includes a fifth extension section arranged in the axial direction;

[0012] The included angle between the end surface of the second abutting portion of the second sealing lip close to the labyrinth seal and the first extension section is α, and the range of α is 10° to 30°;

[0013] An included angle between an end surface of the first abutting portion of the first sealing lip close to the sealing channel and the fifth extending section is θ, and the range of θ is 10° to 30°.

[0014] Furthermore, the first skeleton further comprises a second extension section extending in the axial direction, a first bending portion connected to an end of the first extension section away from the second extension section, and a fifth radial section connected to the first bending portion and extending radially;

[0015] The third skeleton also includes a fourth radial segment that is close to the first extension segment and extends radially, and a sixth bending portion connected to the fourth radial segment. The second sealing lip is fixed to the inner side of the fourth radial segment through a second fixing portion connected to the second abutting portion. The sixth bending portion forms an S-shaped labyrinth seal with the fourth radial segment, the first bending portion, the fifth radial segment, the first extension segment and the second abutting portion of the second sealing lip.

[0016] Furthermore, the second skeleton includes a third extension section and a fourth extension section extending in the axial direction and a first radial section arranged between the third extension section and the fourth extension section and extending in the radial direction, the third extension section and the second extension section are interference fit, the sealing channel is provided between the fourth extension section and the fifth extension section, and the first sealing lip is fixed to the first radial section by a first fixing portion connected to the first abutting portion.

[0017] Furthermore, the axial widths of the first fixing portion and the second fixing portion are greater than 10 mm.

[0018] Furthermore, the fourth extension section and / or the fifth extension section is provided with an annular groove structure, and the annular groove structure is a rectangular groove or a V-shaped groove with two oblique sides of unequal lengths.

[0019] Furthermore, the first sealing lip also includes an extension portion connected to the first fixing portion and the first abutting portion, the extension portion is arranged between the fourth extension section and the fifth extension section, one side of the extension portion is fixed to the inner side of the fourth extension section, and the other side is provided with the annular groove structure.

[0020] Furthermore, the first skeleton further includes a second bending portion provided between the second extension section and the first extension section;

[0021] An oblique angle is provided on one end of the third extension section of the second frame close to the second bending portion.

[0022] Furthermore, a bayonet structure capable of engaging with the outer ring of the bearing is provided on the outer side of the second extension section.

[0023] An axle box bearing for rail transit axle box bearing comprises the sealing structure for rail transit axle box bearing of the present invention.

[0024] The beneficial effects of the present invention are:

[0025] A sealing structure and an axle box bearing for a rail transit axle box bearing disclosed in the present invention, a sealing structure for a rail transit axle box bearing disclosed in the present invention, a sealing channel is provided as a first seal, a first sealing lip abutting against a third frame is a second seal, a second sealing lip abutting against the first frame is a third seal, and a labyrinth channel provided between the first frame and the third frame is a fourth seal. The four-sealing structure can effectively prevent the lubricating fluid inside the bearing from leaking out and external dust and moisture from entering the bearing. Moreover, when the operating temperature of the bearing rises, the lubricating medium can push open the first sealing lip and enter the sealing cavity that can relieve pressure, thereby balancing the pressure difference between the inside and outside of the bearing and preventing sealing failure or damage caused by excessive pressure. Experiments have verified that the sealing structure has good sealing performance and can meet the sealing requirements of rail transit axial bearings, thereby improving the service life and reliability of the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of a sealing structure of the prior art;

[0028] Figure 2 This is a schematic diagram of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Example 1 of the present invention;

[0029] Figure 3 A sealing structure for a rail transit axle box bearing and a cross-sectional view of an axle box bearing disclosed in Example 1 of the present invention;

[0030] Figure 4 A sealing structure for a rail transit axle box bearing and a cross-sectional view of an axle box bearing and a schematic diagram of the flow of lubricating medium disclosed in Example 1 of the present invention;

[0031] Figure 5 A cross-sectional view of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Embodiment 3 of the present invention;

[0032] Figure 6 A cross-sectional view of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Embodiment 4 of the present invention;

[0033] Figure 7 A cross-sectional view of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Example 5 of the present invention;

[0034] Figure 8 A cross-sectional view of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Example 6 of the present invention;

[0035] Fig. 9 A cross-sectional view of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Example 7 of the present invention;

[0036] Fig.10 It is a cross-sectional view of a sealing structure for a rail transit axle box bearing and an axle box bearing structure disclosed in Example 8 of the present invention.

[0037] In the figure:

[0038] 1. first skeleton; 11. first extension section; 12. second extension section; 121. bayonet structure; 13. first bending portion; 14. fifth radial section; 15. second bending portion; 16. seventh bending portion;

[0039] 2. second skeleton; 21. third extension section; 211. oblique angle; 22. fourth extension section; 23. first radial section; 24. second radial section; 25. sixth extension section;

[0040] 3. third skeleton; 31. fifth extension section; 32. fourth radial section; 33. sixth bending portion; 34. fifth bending portion; 35. third radial section;

[0041] 4. first sealing lip; 41. first abutting portion; 42. first fixing portion; 43. extending portion;

[0042] 5. second sealing lip; 51. second abutting portion; 52. second fixing portion;

[0043] 6. Seal the passage;

[0044] 7. Labyrinth seal;

[0045] 8. Sealed cavity;

[0046] 9. Ring groove structure. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Embodiment 1:

[0049] like Figure 2-3 The figure shows a sealing structure for a rail transit axle box bearing and an axle box bearing provided in this embodiment, comprising a first frame 1, a second frame 2, a third frame 3, a first sealing lip 4 and a second sealing lip 5;

[0050] The outer side of the first skeleton 1 is interference fit with the outer ring of the bearing, the third skeleton 3 is interference fit with the inner ring of the bearing, and the second skeleton 2 is interference installed on the inner side of the first skeleton 1;

[0051] A sealing channel 6 is provided between the second frame 2 and the third frame 3 along the axial direction, the first sealing lip 4 is provided on the inner side of the second frame 2, and the first sealing lip 4 abuts against the inner side of the third frame 3;

[0052] A labyrinth seal 7 is provided between the first frame 1 and the third frame 3, the second sealing lip 5 is provided on the inner side of the third frame 3, and the second sealing lip 5 abuts against the inner side of the first frame 1;

[0053] A sealing cavity 8 is formed between the first frame 1 and the second frame 2 , the first sealing lip 4 , the third frame 3 and the second sealing lip 5 .

[0054] The flow of lubricating medium under the action of sealing structure is as follows Figure 4 As shown, the present invention discloses a sealing structure for a rail transit axle box bearing, in which a sealing channel is provided as a first seal, a first sealing lip abutting against a third frame is a second seal, a second sealing lip abutting against the first frame is a third seal, and a labyrinth channel provided between the first frame and the third frame is a fourth seal. The four-sealing structure can effectively prevent the lubricating fluid inside the bearing from leaking out and external dust and moisture from entering the bearing. Moreover, when the operating temperature of the bearing rises, the lubricating medium can push open the first sealing lip and enter into the sealing cavity that can relieve pressure, thereby balancing the pressure difference between the inside and outside of the bearing and preventing sealing failure or damage caused by excessive pressure. Experiments have verified that the sealing structure has good sealing performance and can meet the sealing requirements of rail transit axial bearings.

[0055] Preferably, the first skeleton 1 includes a first extension section 11 extending in the axial direction, and the third skeleton 3 includes a fifth extension section 31 arranged in the axial direction;

[0056] The included angle between the end surface of the second abutting portion 51 of the second sealing lip 5 close to the labyrinth seal 7 and the first extending section 11 is α, and the range of α is 10° to 30°;

[0057] The angle between the end surface of the first abutting portion 41 of the first sealing lip 4 close to the sealing channel 6 and the fifth extending section 31 is θ, and the range of θ is 10° to 30°;

[0058] A light contact sealing fit is formed between the first abutting portion 41 of the first sealing lip 4 and the fifth extending section 31 of the third frame 3, and a light contact sealing fit is formed between the second abutting portion 51 of the second sealing lip 5 and the first extending section 11 of the first frame 1;

[0059] Setting the angle of the second abutment portion 51 of the second sealing lip 5 and the first abutment portion 41 of the first sealing lip 4 within the range of 10° to 30° can ensure the sealing effect and waterproof effect of the sealing structure, and effectively prevent the leakage of the lubricating medium inside the bearing and the entry of external moisture and dust; in this embodiment, the angles α and θ are both set to 20°.

[0060] Preferably, the first skeleton 1 further comprises a second extension section 12 extending in the axial direction, a first bending portion 13 connected to an end of the first extension section 11 away from the second extension section 12, and a fifth radial section 14 connected to the first bending portion 13 and extending radially;

[0061] The third skeleton 3 also includes a fourth radial segment 32 which is radially extended and close to the first extension segment 11, and a sixth bending portion 33 which is connected to the fourth radial segment 32. The second sealing lip 5 is fixed to the inner side of the fourth radial segment 32 via a second fixing portion 52 which is connected to the second abutting portion 51. The sixth bending portion 33 forms an S-shaped labyrinth seal 7 with the fourth radial segment 32, the first bending portion 13, the fifth radial segment 14, the first extension segment 11 and the second abutting portion 51 of the second sealing lip 5.

[0062] Specifically, the fifth extension segment 31 of the third skeleton 3 is connected to the fourth radial segment 32 in sequence through the fifth bending portion 34, the radially extending third radial segment 35, and the sixth bending portion 33; the formed S-shaped labyrinth seal 7 can cooperate with the sealing channel 6 to ensure the sealing performance and sealing effect of the bearing.

[0063] Preferably, the second skeleton 2 includes a third extension section 21 and a fourth extension section 22 extending in the axial direction and a first radial section 23 arranged between the third extension section 21 and the fourth extension section 22 and extending in the radial direction. The third extension section 21 is interference fit with the second extension section 12, and the sealing channel 6 is provided between the fourth extension section 22 and the fifth extension section 31. The first sealing lip 4 is fixed to the first radial section 23 by a first fixing portion 42 connected to the first abutting portion 41.

[0064] The second skeleton 2 is an S-shaped structure. When the second skeleton 2 is an S-shaped structure, the second skeleton 2 further includes a second radial section 24 disposed between the third extension section 21 and the first radial section 23 and radially arranged, and a sixth extension section 25 disposed along the axial direction. The third extension section 21 is connected to the fourth extension section 22 through the second radial section 24, the sixth extension section 25, and the first radial section 23 in sequence.

[0065] The second frame 2 is not limited to a C-shaped structure, as long as it includes a third extension section 21 that is interference-fitted with the first extension section 11 of the first frame 1, a fourth extension section 22 that forms a sealing channel 6 with the fifth extension section 31, and a first radial section 23 for mounting the first sealing lip 4.

[0066] The first skeleton 1, the second skeleton 2, and the third skeleton 3 are all formed by stamping steel plates, and the first sealing lip 4 and the second sealing lip 5 are both made of nitrile rubber or fluororubber. Nitrile rubber has good low-temperature resistance, and fluororubber has good high-temperature resistance. The material can be selected according to the actual operating temperature of the bearing; the first fixing portion 42 of the first sealing lip 4 and the first radial section 23 of the first skeleton 1, and the second fixing portion 52 of the second sealing lip 5 and the fourth radial section 32 of the second skeleton 2 are both connected by vulcanization process.

[0067] Preferably, the axial width of the first fixing portion 42 and the second fixing portion 52 is greater than 10 mm to ensure the bonding strength between the first sealing lip 4 and the second frame 2 and between the second sealing lip 5 and the third frame 3, thereby ensuring the sealing performance of the sealing structure.

[0068] Preferably, the first skeleton 1 further includes a second bending portion 15 disposed between the second extension segment 12 and the first extension segment 11;

[0069] An end of the third extension section 21 of the second skeleton 2 close to the second bending portion 15 is provided with an oblique angle 211; the provided oblique angle can avoid assembly interference at the rounded corner of the second bend;

[0070] Specifically, a seventh bending portion 16 connecting the first extension segment 11 and the second bending portion 15 is provided between the two, that is, the second extension segment 12 is connected to the fifth radial segment 14 through the second bending portion 15, the seventh bending portion 16, the first extension segment 11, the first bending portion 13 in sequence, and the first skeleton 1 as a whole is connected in the shape of two "7s".

[0071] Preferably, a bayonet structure 121 capable of being engaged with the outer ring of the bearing is provided on the outer side of the second extension section 12; specifically, in the present embodiment, the bayonet is a trapezoidal protrusion structure, which can be engaged with a groove provided on the outer ring of the bearing to ensure the reliability of the connection between the first skeleton 1 and the outer ring of the bearing during the operation of the bearing.

[0072] Embodiment 2:

[0073] This embodiment provides an axle box bearing for rail transit axle box bearings. The second extension section 12 of the second skeleton 2 of the sealing structure disclosed in the present invention is interference connected with the outer ring of the bearing, and the fifth extension section 31 of the third skeleton 3 is interference connected with the inner ring of the bearing.

[0074] Embodiment 3:

[0075] The difference between this embodiment and embodiment 1 is that, in this embodiment, Figure 5 As shown, the second skeleton 2 is a C-shaped structure, the third extension segment 21 of the C-shaped second skeleton is connected to the fourth extension segment 22 through the first radial segment 23, and the end of the third extension segment 21 close to the second bending portion 15 is not provided with an angle 211 (no need to set an angle).

[0076] Embodiment 4:

[0077] The difference between this embodiment and embodiment 1 is that, in this embodiment, Figure 6 As shown, the fourth extension section 22 is provided with an annular groove structure 9, which is a rectangular groove. The rectangular groove can make the lubricating medium experience multiple turns and obstacles when passing through the sealing channel 6. The tortuous flow channel greatly increases the flow resistance of the leakage medium, thereby improving the sealing effect of the sealing structure.

[0078] Embodiment 5:

[0079] The difference between this embodiment and embodiment 4 is that, in this embodiment, Figure 7 As shown, the fourth extension section 22 and the fifth extension section 31 are both provided with an annular groove structure 9, that is, an annular groove structure is processed on both sides, and the annular groove structure is a rectangular groove; the double-sided rectangular groove greatly increases the flow resistance of the leakage medium, thereby improving the sealing ability of the sealing structure, thereby ensuring the service life and reliability of the bearing.

[0080] Embodiment 6:

[0081] The difference between this embodiment and embodiment 4 is that, in this embodiment, Figure 8 As shown, the fourth extension section 22 is provided with an annular groove structure 9, and the annular groove structure is a V-shaped groove with two oblique sides of unequal lengths; the V-shaped groove can make the lubricating medium experience multiple turns and obstacles when passing through the sealing channel 6, and the tortuous flow channel greatly increases the flow resistance of the leakage medium, thereby improving the sealing performance of the sealing structure; the length of the oblique side of the V-shaped groove in the direction of the flow of the lubricating medium is greater than the length of the other oblique side, so as to increase the pressure on the lubricating medium, thereby improving the blocking ability of the lubricating medium.

[0082] Embodiment 7:

[0083] The difference between this embodiment and embodiment 6 is that, in this embodiment, Fig. 9 As shown, the second skeleton 2 is a C-shaped structure, and the first sealing lip 4 also includes an extension portion 43 connected to the first fixing portion 42 and the first abutting portion 41, and the extension portion is arranged between the fourth extension section 22 and the fifth extension section 31, and one side of the extension portion is fixed on the inner side of the fourth extension section 22, and the other side is provided with the annular groove structure 9; since the sealing lip is made of rubber material, the processing is relatively simple, and the annular groove structure 9 is arranged on the extension portion, which not only ensures the sealing effect but also facilitates processing and saves production costs.

[0084] Embodiment 8:

[0085] The difference between this embodiment and embodiment 1 is that, in this embodiment, Fig.10 As shown, the first skeleton 1 is configured as three "7"-shaped connected structures to meet the needs of different bearing installation sizes. In practical applications, the structure (axial length) of the first skeleton can also be adjusted according to actual needs.

[0086] The sealing durability test of this device is carried out, and the test items and methods are shown in Table 1:

[0087] Table 1 Sealing durability test basis

[0088]

[0089] Test equipment: Railway oil seal bench test machine.

[0090] The test results are shown in Table 2:

[0091] Table 2 Sealing durability test results

[0092]

[0093] It can be seen from the data in Table 2 that the sealing structure has good sealing performance for the bearing and can meet the sealing requirements of the axle box bearing for rails.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sealing structure for rail transit axle box bearings, It is characterized in that It comprises a first frame (1), a second frame (2), a third frame (3), a first sealing lip (4) and a second sealing lip (5); The outer side of the first frame (1) is interference-fitted with the outer ring of the bearing, the third frame (3) is interference-fitted with the inner ring of the bearing, and the second frame (2) is interference-mounted on the inner side of the first frame (1); A sealing channel (6) is provided between the second frame (2) and the third frame (3) along the axial direction, the first sealing lip (4) is provided on the inner side of the second frame (2), and the first sealing lip (4) abuts against the inner side of the third frame (3); A labyrinth seal (7) is provided between the first frame (1) and the third frame (3); the second sealing lip (5) is provided on the inner side of the third frame (3); the second sealing lip (5) abuts against the inner side of the first frame (1); A sealing cavity (8) is formed between the first frame (1) and the second frame (2), the first sealing lip (4), the third frame (3) and the second sealing lip (5).

2. A sealing structure for a rail transit axle box bearing according to claim 1, It is characterized in that The first skeleton (1) comprises a first extension section (11) extending in the axial direction, and the third skeleton (3) comprises a fifth extension section (31) arranged in the axial direction; An included angle α between an end surface of the second abutting portion (51) of the second sealing lip (5) close to the labyrinth seal (7) and the first extending section (11) is 10° to 30°; The angle between the end surface of the first abutting portion (41) of the first sealing lip (4) close to the sealing channel (6) and the fifth extending section (31) is θ, and the range of θ is 10° to 30°.

3. A sealing structure for a rail transit axle box bearing according to claim 2, It is characterized in that The first skeleton (1) further comprises a second extension section (12) extending in the axial direction, a first bending portion (13) connected to an end of the first extension section (11) away from the second extension section (12), and a fifth radial section (14) connected to the first bending portion (13) and extending radially; The third skeleton (3) also includes a fourth radial segment (32) which is close to the first extension segment (11) and radially extends, and a sixth bending portion (33) connected to the fourth radial segment (32); the second sealing lip (5) is fixed to the inner side of the fourth radial segment (32) by a second fixing portion (52) connected to the second abutting portion (51); the sixth bending portion (33) forms an S-shaped labyrinth seal (7) with the fourth radial segment (32), the first bending portion (13), the fifth radial segment (14), the first extension segment (11) and the second abutting portion (51) of the second sealing lip (5).

4. A sealing structure for a rail transit axle box bearing according to claim 3, It is characterized in that The second skeleton (2) comprises a third extension section (21) and a fourth extension section (22) extending in an axial direction, and a first radial section (23) arranged between the third extension section (21) and the fourth extension section (22) and extending in a radial direction, the third extension section (21) and the second extension section (12) are interference fit, the sealing channel (6) is provided between the fourth extension section (22) and the fifth extension section (31), and the first sealing lip (4) is fixed to the first radial section (23) by a first fixing portion (42) connected to the first abutting portion (41).

5. A sealing structure for a rail transit axle box bearing according to claim 4, It is characterized in that The axial width of the first fixing portion (42) and the second fixing portion (52) is greater than 10 mm.

6. A sealing structure for a rail transit axle box bearing according to claim 4, It is characterized in that The fourth extension section (22) and / or the fifth extension section (31) are provided with an annular groove structure (9), wherein the annular groove structure is a rectangular groove or a V-shaped groove with two oblique sides of unequal lengths.

7. A sealing structure for a rail transit axle box bearing according to claim 6, It is characterized in that The first sealing lip (4) further comprises an extension portion (43) connected to the first fixing portion (42) and the first abutting portion (41); the extension portion is arranged between the fourth extension section (22) and the fifth extension section (31); one side of the extension portion is fixed to the inner side of the fourth extension section (22); and the other side is provided with the annular groove structure (9).

8. A sealing structure for a rail transit axle box bearing according to claim 4, It is characterized in that The first skeleton (1) further comprises a second bending portion (15) arranged between the second extension section (12) and the first extension section (11); An oblique angle (211) is provided on one end of the third extension section (21) of the second frame (2) close to the second bending portion (15).

9. A sealing structure for a rail transit axle box bearing according to claim 3, It is characterized in that A bayonet structure (121) capable of being engaged with the outer ring of the bearing is provided on the outer side of the second extension section (12).

10. An axle box bearing for rail transit axle box bearing, It is characterized in that The bearing has a sealing structure for a rail transit axle box bearing according to any one of claims 1 to 9.

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