CN111749982A

CN111749982A - Axle bearing device

Info

Publication number: CN111749982A
Application number: CN202010201811.3A
Authority: CN
Inventors: 铃木健吾
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2019-03-26
Filing date: 2020-03-20
Publication date: 2020-10-09
Also published as: JP2020159454A

Abstract

The invention provides a bearing device for an axle. An axle bearing device (1) is provided with: a rolling bearing (2); and a first spacer (15) disposed between a mating surface (17) of the inner ring (5) of the rolling bearing (2) and a mating surface (18) of the washer (8). The mating surface (17) of the inner ring (5) and the mating surface (18) of the washer (8) have direct contact sections (19) that contact each other on the inner diameter side. The first spacer (15) is provided with: a core (20) that abuts against the mating surface (18) of the washer (8) on the outer diameter side of the direct abutment portion (19) and that has an axial gap (G1) between itself and the inner ring (5); and an elastic seal member (21) that seals between the mating surface (17) of the inner ring (5) and the mating surface (18) of the gasket (8) on the outer diameter side of the axial gap (G1).

Description

Axle bearing device

Technical Field

The present invention relates to an axle bearing device for an axle of a railway vehicle.

Background

Conventionally, as a bearing device for an axle of a railway vehicle, there is a bearing device including a tapered roller bearing as a rolling bearing and a positioning member for positioning the tapered roller bearing with respect to the axle.

The tapered roller bearing includes a pair of inner rings having raceway surfaces on outer circumferential surfaces thereof, an outer ring having double-row raceway surfaces on inner circumferential surfaces thereof, and tapered rollers rotatably held between the raceway surfaces of the inner rings and the raceway surfaces of the outer ring.

The positioning member is fitted to the outer peripheral surface of the axle and positions the inner race of the tapered roller bearing in the axial direction with respect to the axle. Examples of the positioning member include a rear cover disposed on the rear end side in the axial direction of the inner ring, a slinger (or a front cover) disposed on the front end side in the axial direction of the inner ring, and a gasket disposed between the pair of inner rings. The tapered roller bearing is positioned at a predetermined position of the axle by bringing the positioning members and the inner ring into contact with each other.

In the axle bearing device described above, when a radial load unique to the railway vehicle is applied to the axle, a bending moment acts on the axle, and the axle deflects. As a result of the rotation of the axle in the flexed state, repeated stress is generated at the contact portion of the inner race and the rear cover and frictional wear is generated at the contact portion.

Frictional wear is inevitable for a railway vehicle in which a radial load is applied to an axle, and if the wear progresses, the axial accuracy of the tapered roller bearing is degraded. The generated wear powder enters the inside of the bearing to deteriorate the lubricant sealed in the internal space, which also causes shortening of the life of the bearing device. In view of the above, for example, in the bearing device of patent document 1, a resin spacer is disposed between the inner ring and the rear cover in order to suppress frictional wear between them.

In recent years, in order to further extend the life of the bearing device, it is sometimes desired to suppress frictional wear at a contact portion between the inner ring and the washer. In view of the above, for example, in the bearing device of patent document 1, a resin spacer is disposed between an inner ring and a washer (spacer ring) in order to suppress frictional wear therebetween.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication Hei-2004-500518

In the bearing device of patent document 1, the thickness of the resin spacer disposed between the inner ring and the positioning member directly affects the positioning accuracy of the inner ring. However, the resin spacer is more likely to deform than the inner ring and the positioning member, and the thickness of the resin spacer changes in accordance with the pressing force acting between the inner ring and the positioning member. As a result, the axial accuracy of the bearing is reduced at the time of assembly, and management of the clearance inside the bearing becomes difficult.

In addition, creep deformation occurs in the resin spacer in accordance with the period of use, and a gap due to positional displacement of the inner ring may be formed between the inner ring and the positioning member. In the structure in which such a gap is formed, the axial accuracy of the bearing is likely to be lowered even when the bearing is used, as in the case of assembly. Therefore, it is difficult to maintain the axial accuracy of the bearing over a long period of time, and the life of the bearing device cannot be sufficiently extended.

Disclosure of Invention

Problems to be solved by the invention

The present invention aims to extend the life of a bearing device by reliably suppressing the friction wear and the accompanying penetration of wear powder into the bearing and maintaining the axial accuracy of the bearing for a long time.

Means for solving the problems

The present invention made to solve the above problems is an axle bearing device including: a rolling bearing having an inner ring and an outer ring; a positioning member that is fitted to an outer peripheral surface of the axle and that positions the inner race in an axial direction with respect to the axle; and a spacer disposed between the mating surface of the inner ring and the mating surface of the positioning member, wherein the mating surface of the inner ring and the mating surface of the positioning member have direct contact portions that contact each other on an inner diameter side, the spacer including: a core bar that abuts either one of a mating surface of the inner ring and a mating surface of the positioning member on an outer diameter side of the direct abutment portion, and that has an axial gap with the other; and an elastic seal member that seals between the mating surface of the inner race and the mating surface of the positioning member at a position closer to the outer diameter side than the axial gap.

In this way, the outer diameter side between the mating surface of the inner ring and the mating surface of the positioning member is sealed by the elastic seal, and therefore even if abrasion powder due to frictional wear is generated between the mating surface of the inner ring and the mating surface of the positioning member, the penetration of the abrasion powder into the bearing interior can be suppressed.

When the axle is assembled, the inner ring can be accurately positioned with respect to the axle by the direct contact between the mating surface of the inner ring and the mating surface of the positioning member. At this time, since an axial gap exists between the core metal and the mating surface of the inner ring or the mating surface of the positioning member, the core metal does not positively press the inner ring. In other words, the core bar does not adversely affect the positioning of the inner ring by the direct abutment.

Due to the deflection of the axle during use, for example, a pressurized region in which a force that narrows the gap between the mating surface of the inner ring and the mating surface of the positioning member acts is formed in the lower region of the axle, and a depressurized region in which a force that widens the gap between the mating surface of the inner ring and the mating surface of the positioning member acts is formed in the upper region of the axle. In the pressurized region, at least a portion of the axial gap is eliminated with compressive deformation of the resilient seal. As a result, at least a part of the core bar is in contact with both the mating surface of the inner ring and the mating surface of the positioning member. By this contact of the core, the pressing force acting on the direct contact portion can be dispersed to the core, and the pressing force acting on the direct contact portion in the pressurized region can be relatively reduced. Therefore, in use, the difference between the pressing force acting on the direct contact portion in the decompression region and the pressing force acting on the direct contact portion in the pressurization region can be reduced. Therefore, the repeated stress acting along with the rotation of the axle can be reduced, and the frictional wear of the direct contact part can be suppressed. Further, since the frictional wear tends to be smaller on the inner diameter side than on the outer diameter side, the frictional wear of the direct contact portion can be more reliably suppressed by providing the direct contact portion on the inner diameter side. In other words, if the inner race is accurately positioned with respect to the axle by the direct contact portion at the time of assembly, the axial accuracy of the bearing can be maintained for a long time by the direct contact portion even at the time of subsequent use.

In the above-described configuration, it is preferable that either one of the mating surface of the inner ring and the mating surface of the positioning member includes an axial recessed portion at a position on an outer diameter side of the direct contact portion, and the core includes an axial protruding portion that engages with the axial recessed portion.

In this way, the axial direction concave portion and the axial direction convex portion are engaged with each other, and the radial movement of the spacer can be regulated, so that the spacer assembling work and the bearing device assembling work can be efficiently performed.

In the above-described configuration, the pair of inner rings are arranged with a gap therebetween in the axial direction, and the positioning member includes a washer that is arranged between the pair of inner rings with the spacer interposed therebetween and has a mating surface that is joined to the inner rings on both end sides in the axial direction.

Thus, frictional wear between the mating surface of the inner ring and the mating surface of the washer can be suppressed.

In the case where the inner ring is divided into two parts and the positioning member includes a washer, the core preferably includes: a pair of first metal parts disposed between a mating surface of one inner ring and a mating surface of the washer provided on one end side in the axial direction, and between a mating surface of the other inner ring and a mating surface of the washer provided on the other end side in the axial direction; and a second metal portion disposed on an outer peripheral surface of the gasket and connecting the pair of first metal portions.

In this way, the axial distance between the pair of first metal parts can be maintained constant by the second metal part, and therefore, the spacer provided with the core metal can be easily arranged with respect to the mating surfaces provided at both ends of the washer in the axial direction.

When the core includes the first metal portion and the second metal portion, the first metal portion preferably abuts against the mating surface of the washer and has an axial gap with the mating surface of the inner ring.

In the case where the core bar includes the first metal portion and the second metal portion, an axial gap is formed between the mating surface of the gasket and the first metal portion during assembly, and when the first metal portion (core bar) is brought into contact with both the mating surfaces of the pair of inner rings, the mating surfaces of the inner rings may be prevented from coming into direct contact with the mating surfaces of the gasket. This is because the second metal portion (axial portion of the core metal) contacts and supports both mating surfaces of the inner ring before the mating surfaces of the washer. In contrast, if the first metal part is brought into contact with the mating surface of the washer and an axial gap is formed between the first metal part and the mating surface of the inner ring as in the above-described configuration, the mating surface of the inner ring can be reliably brought into direct contact with the mating surface of the washer without causing such a problem. In other words, the direct abutment is easily formed.

In the above-described configuration, it is preferable that the positioning member includes a rear cover that is disposed on a rear end side in the axial direction of the inner ring with the spacer interposed therebetween and has a mating surface that is joined to the inner ring on a front end side in the axial direction.

Thus, frictional wear between the mating surface of the inner ring and the mating surface of the rear cover can be suppressed.

In addition to the above-described structure, the hardness of the core bar is preferably lower than that of the inner ring.

This can more reliably suppress the frictional wear of the inner ring.

In this case, the core is preferably made of a cold-rolled steel sheet, a hot-rolled mild steel sheet, a high-tensile steel sheet, a stainless steel sheet, a high-melting-point plated steel sheet, or a brass sheet.

This can provide the core with appropriate hardness.

In addition to the above-described structure, it is preferable that the elastic seal is made of nitrile rubber, acrylic rubber, or fluororubber.

This improves the heat resistance, oil resistance, and abrasion resistance of the elastic seal member.

Effects of the invention

According to the present invention, it is possible to reliably suppress the friction wear and the accompanying intrusion of the wear powder into the bearing interior, and to maintain the axial accuracy of the bearing over a long period of time, so that the life of the axle bearing device can be extended.

Drawings

Fig. 1 is a sectional view showing the entire structure of an axle bearing device according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view of the gasket of fig. 1.

Fig. 3 is a sectional view for explaining a step of fitting the first spacer into the gasket.

Fig. 4 is a sectional view showing a state in which the first spacer is incorporated in the gasket.

Fig. 5 is a cross-sectional view showing the rear cover of fig. 1 enlarged in its periphery.

Fig. 6 is an enlarged cross-sectional view of the periphery of the gasket of fig. 1 in a pressurized region during use.

Fig. 7 is a cross-sectional view showing the gasket periphery of fig. 1 in an enlarged manner in a decompression region in use.

Fig. 8 is an enlarged cross-sectional view of the periphery of a washer of an axle bearing device according to another embodiment of the present invention.

Fig. 9 is an enlarged cross-sectional view of the periphery of a washer of an axle bearing device according to another embodiment of the present invention.

Description of reference numerals:

1 bearing device

2 rolling bearing

3 sealing device

4 outer ring

5 inner ring

6 tapered roller

7 holder

8 gasket

10 rear cover

15 first spacer

16 second spacer

19 direct contact part

20 core rod

21 elastic sealing element

26 direct abutment

27 core rod

28 elastic sealing element

G1 axial gap

G2 axial gap

And (S) an axle.

Detailed Description

Hereinafter, embodiments of the present invention will be described based on the drawings. In the present specification, the "axial direction" refers to the axial direction (longitudinal direction) of the axle. The position near the axial end of the axle is referred to as "front", and the position near the axial center of the axle is referred to as "rear". The term "radial direction" basically refers to the radial direction of an axle, but may also refer to the radial direction of a member (e.g., a front cover, a rear cover, an inner ring, an outer ring, etc. of a rolling bearing) disposed concentrically with the axle. When describing the relative positional relationship, a position on the inner side in the radial direction (a position close to the axle) is referred to as an "inner diameter side", and a position on the outer side in the radial direction from the inner diameter side (a position apart from the axle) is referred to as an "outer diameter side".

Fig. 1 shows an example in which an axle bearing device (hereinafter, simply referred to as a bearing device) 1 according to an embodiment of the present invention is incorporated in an axle S of a railway vehicle. The bearing device 1 includes a rolling bearing 2 for rotatably supporting the axle S and a pair of sealing devices 3.

The rolling bearing 2 is a so-called double row tapered roller bearing, and includes an outer ring 4, a pair of inner rings 5, a plurality of tapered rollers 6 as rolling elements, and a cage 7.

The outer ring 4 has a conical raceway surface 4a arranged in two rows on the inner circumferential surface.

Each of the pair of inner rings 5 has a conical raceway surface 5a on the outer peripheral surface. A washer 8 is provided between the pair of inner rings 5. The pair of inner rings 5 are arranged such that the ends on the small diameter side thereof face each other in the axial direction with a washer 8 interposed therebetween.

The plurality of tapered rollers 6 are arranged in two rows corresponding to the double row raceway surface 4a of the outer ring 4 and the raceway surfaces 5a of the pair of inner rings 5.

The retainer 7 holds the tapered rollers 6 of each row at equal intervals in the circumferential direction.

The outer ring 4 is fitted to an inner peripheral surface of an axle box (not shown) of the railway vehicle. On the other hand, the inner ring 5 is fitted to the outer peripheral surface of the axle S. Oil slingers 9 and a rear cover 10 are provided on the front end side and the rear end side of the outer portions of the bearings of the pair of inner rings 5, respectively. A front cover 11 is fixed to a front end (shaft end) of the axle S by a bolt 12, and a slinger 9, a washer 8, and a rear cover 10 attached to an outer peripheral surface of the axle S are sandwiched and fixed between the front cover 11 and a shoulder Sa of the axle S together with the inner ring 5. In other words, in the present embodiment, the slinger 9, the washer 8, and the rear cover 10 are positioning members for positioning the inner ring 5 in the axial direction. These positioning members are cylindrical so as to be fitted to the outer peripheral surface of the axle S.

A lubricant such as grease is sealed in a bearing inner space formed between the outer ring 4 and the inner ring 5.

The pair of sealing devices 3 seal both front and rear end portions of the bearing internal space in which the lubricant is sealed. Each sealing device 3 includes a seal member 13 and a stepped cylindrical seal cover 14 having an outer diameter side end fixed to the outer ring 4 and an inner diameter side end disposed close to the slinger 9 or the rear cover 10. The seal member 13 is fitted to the inner peripheral surface of the seal cover 14. The sealing member 13 may be either of a so-called contact type or a non-contact type.

A first spacer 15 is disposed between the inner race 5 and the washer 8, and a second spacer 16 is disposed between the rear cover 10 and the inner race 5.

As shown in fig. 2, mating surfaces 17 of the pair of inner rings 5 adjacent to the first spacer 15 are provided on the rear end side of the front inner ring 5 and the front end side of the rear inner ring 5, respectively. The mating surface 17 of each inner race 5 is a radially extending end surface. Mating surfaces 18 of the gasket 8 adjacent to the first spacer 15 are provided on both front and rear end sides of the gasket 8. Each mating surface 18 of the washer 8 includes an inner diameter side end surface 18a extending in the radial direction and an outer diameter side end surface 18b extending in the radial direction at a position axially (rearward or forward) farther from the mating surface 17 of the inner ring 5 than the inner diameter side end surface 18 a. The inner diameter side portion of the mating surface 17 of the inner ring 5 and the inner diameter side end surface 18a of the washer 8 constitute a direct contact portion 19 that directly contacts each other.

The first spacer 15 includes a core 20 and an elastic seal 21 formed integrally with the core 20. The core member 20 and the elastic seal 21 may be separate members separable from each other.

The core 20 includes a pair of first metal portions 22 that abut against the outer diameter side end surface 18b of the mating surface 18 of the washer 8 and have an axial gap G1 between the mating surface 17 of the inner ring 5, and a second metal portion 23 that connects the outer diameter side end portions of the pair of first metal portions 22 and abuts against the outer circumferential surface 8a of the washer 8 extending in the axial direction. The first metal part 22 and the second metal part 23 may directly contact the gasket 8 as in the illustrated example, or may contact the gasket 8 through an elastic seal (not illustrated).

The first metal part 22 has a circular plate shape, and the second metal part 23 has a cylindrical shape. The axial separation distance of the pair of first metal parts 22 is maintained constant by the second metal part 23.

The first metal part 22 includes a thick portion 22a provided on the inner diameter side, and a thin portion 22b provided on the outer diameter side of the thick portion 22a and axially (rearward or forward) farther from the mating surface 17 of the inner ring 5 than the thick portion 22 a. In other words, an axial step portion 22x is formed between the thick portion 22a and the thin portion 22b on the mating surface 17 side of the inner ring 5 of the first metal portion 22, and the thick portion 22a and the thin portion 22b are smoothly continuous on the mating surface 18 side of the gasket 8 of the first metal portion 22. The thickness of the first metal part 22 may be constant.

The axial gap G1 is formed at a position on the outer diameter side of the direct contact portion 19 and at a position corresponding to the vicinity of the inner diameter side end of the thick portion 22a and the thin portion 22 b. In the present embodiment, the elastic seal 21 is not in contact with the mating surface 17 of the inner ring 5 through the axial gap G1 at a position corresponding to the vicinity of the inner diameter side end portion of the thin portion 22 b.

The axial gap G1 is formed in a state where the axle S is not deflected during assembly or the like, and the size of the axial gap G1 changes in accordance with the deflection of the axle S. The size of the axial gap G1 is set to a range in which at least a part of the first metal portion 22 of the core bar 20 can contact both the mating surface 17 of the inner ring 5 and the mating surface 18 of the washer 8 when the elastic seal 21 is compressively deformed by the deflection of the axle S (see fig. 6).

The elastic seal member 21 is capable of undergoing expansion deformation or compression deformation in accordance with the deflection of the axle S, and seals between the mating surface 17 of the inner race 5 and the mating surface 18 of the washer 8 at a position on the outer diameter side of the axial gap G1. Specifically, the elastic seal 21 covers the outer surface (outer peripheral surface) of the second metal portion 23 and the outer surface (inner ring 5 side surface) of the thin portion 22b of the first metal portion 22 continuous with the second metal portion 23. Thus, when viewed from the outer diameter side, the mating surfaces 17 of the pair of inner rings 5 are covered with the elastic seal 21. The elastic seal 21 preferably extends in the radial direction and is sandwiched from both sides by a pair of wall surfaces (in the illustrated example, the mating surfaces 17 of the inner rings 5) facing each other in the axial direction, so as to improve the sealing performance.

The first spacer 15 is divided into a plurality of (for example, two) in the circumferential direction, and as shown in fig. 3, each part of the divided first spacer 15 can be fitted from the outer diameter side with respect to the washer 8.

The washer 8 has an axial recessed portion 18c between the inner diameter side end surface 18a and the outer diameter side end surface 18b, and the first metal portion 22 of the core 20 has an axial projecting portion 22c at the inner diameter side end portion, which engages with the axial recessed portion 18 c. By engaging the axial convex portion 22c with the axial concave portion 18c, even if the first spacer 15 is divided in the circumferential direction, the axial convex portion 22c is hooked on the axial concave portion 18c, and the radial movement of the first spacer 15 with respect to the washer 8 is restricted. The axial recessed portions 18c and the axial projecting portions 22c may be provided intermittently in the circumferential direction, but are provided over the entire circumference in the present embodiment. The axial recessed portion 18c and the axial projecting portion 22c may be omitted.

As shown in fig. 4, in a state where the first spacer 15 is mounted on the washer 8 (a state before the inner ring 5 is positioned), when the maximum width in the axial direction of the elastic seal 21 is a, the maximum width in the axial direction of the core 20 is B, and the maximum width in the axial direction of the inner diameter side end surface 18a of the washer 8 is C, a > C > B is satisfied. As a result, as shown in fig. 2, in a state where the washer 8 is pressed against the inner ring 5 to position the inner ring 5 with respect to the axle S, the elastic seal 21 of the first spacer 15 disposed between the washer 8 and the inner ring 5 is compressed by a predetermined compression margin α ((a-C)/2), thereby improving the sealing performance. In addition, in a state where the inner diameter side end surface 18a of the elastic seal 21 and the washer 8 is brought into contact with the mating surface 17 of the inner ring 5, an axial gap G1 is automatically formed between the core bar 20 and the inner ring 5. The compression margin α of the elastic seal 21 is set within a range in which the elastic seal 21 can be compressively deformed and expand and deform. Specifically, the compression margin α is, for example, 0.1 to 0.5 mm.

As shown in fig. 5, the mating surface 24 of the inner race 5 adjacent to the second spacer 16 is provided on the rear end side of the inner race 5 on the rear side. The mating surface 24 of the inner race 5 is a radially extending end surface. The mating surface 25 of the rear cover 10 adjacent to the second spacer 16 is provided on the front end side of the rear cover 10. The mating surface 25 of the rear cover 10 includes an inner diameter side end surface 25a extending in the radial direction and an outer diameter side end surface 25b extending in the radial direction at a position shifted to the rear side from the inner diameter side end surface 25 a. The inner diameter side portion of the mating surface 24 of the inner ring 5 and the inner diameter side end surface 25a of the rear cover 10 constitute a direct contact portion 26 directly contacting each other.

The second spacer 16 includes a core 27 and an elastic seal 28 formed integrally with the core 27. The core 27 and the elastic seal 28 are separate members that can be separated from each other.

The core 27 abuts against the outer diameter side end surface 25b of the mating surface 25 of the back cover 10, and includes a first metal portion 29 having an axial gap G2 with the mating surface 24 of the inner ring 5, and a second metal portion 30 connected to the outer diameter side end portion of the first metal portion 29 and abutting against the outer circumferential surface 10a of the back cover 10 extending in the axial direction. The first metal part 29 and the second metal part 30 may be in direct contact with the rear cover 10 as in the illustrated example, or may be in contact with the rear cover 10 via an elastic seal (not illustrated).

The first metal part 29 has a circular plate shape, and the second metal part 30 has a cylindrical shape. The second spacer 16 may be divided in the circumferential direction, but in the present embodiment, it is a single member that is not divided in the circumferential direction. The radial movement of the second spacer 16 with respect to the rear cover 10 is restricted by the second metal portion 30. In this case, the second spacer 16 can be fitted with respect to the rear cover 10 from the axial direction. The core 27 may be a plate-like body made of only the first metal part 29, with the second metal part 30 omitted.

The first metal part 29 includes a thick part 29a provided on the inner diameter side, and a thin part 29b provided on the outer diameter side of the thick part 29a and spaced further rearward than the thick part 29a from the mating surface 24 of the inner ring 5. In other words, an axial step portion 29x is formed between the thick portion 29a and the thin portion 29b on the mating surface 24 side of the inner ring 5 of the first metal portion 29, and the thick portion 29a and the thin portion 29b are smoothly continuous on the mating surface 25 side of the rear cover 10 of the first metal portion 29. The thickness of the first metal part 29 may be constant.

The axial gap G2 is formed at a position on the outer diameter side of the direct contact portion 26 and at a position corresponding to the vicinity of the inner diameter side end portions of the thick portion 29a and the thin portion 29 b. In the present embodiment, the elastic seal 28 is not in contact with the mating surface 24 of the inner ring 5 through the axial gap G2 at a position corresponding to the vicinity of the inner diameter side end portion of the thin portion 29 b.

The axial gap G2 is formed in a state where the axle S is not deflected during assembly or the like, and the size of the axial gap G2 changes in accordance with the deflection of the axle S. The size of the axial gap G2 is set to a range in which at least a part of the first metal portion 29 of the core 27 can contact both the mating surface 24 of the inner race 5 and the mating surface 25 of the rear cover 10 when the elastic seal 28 is compressively deformed by the deflection of the axle S.

The elastic seal 28 is capable of undergoing expansion deformation or compression deformation in accordance with the deflection of the axle S, and seals between the mating surface 24 of the inner race 5 and the mating surface 25 of the rear cover 10 at a position on the outer diameter side of the axial gap G2. Specifically, the elastic seal 28 covers the outer surface (outer peripheral surface) of the second metal portion 30 and the outer surface (inner ring 5 side surface) of the thin portion 29b of the first metal portion 29 continuous with the second metal portion 30. Thus, when viewed from the outer diameter side, the space between the mating surface 24 of the inner ring 5 and the mating surface 25 of the rear cover 10 is covered with the elastic seal 28. The elastic seal 28 preferably extends in the radial direction and is sandwiched from both sides by a pair of wall surfaces (in the illustrated example, the mating surface 24 of the inner ring 5 and the radially extending outer circumferential surface 10b of the rear cover 10) facing each other in the axial direction, so as to improve the sealing performance.

The core 20 of the first spacer 15 and the core 27 of the second spacer 16 preferably have a lower hardness than the inner race 5. The

core members

20 and 27 are preferably made of, for example, a cold-rolled steel sheet, a hot-rolled mild steel sheet, a high-tensile steel sheet, a stainless steel sheet, a high-melting-point plated steel sheet, or a brass sheet. The thickness of the

core members

20, 27 is preferably 0.8 to 2.0mm, for example.

The elastic seal 21 of the first spacer 15 and the elastic seal 28 of the second spacer 16 are preferably made of nitrile rubber, acrylic rubber, or fluororubber.

According to the bearing device 1 having the above configuration, the following operational effects can be obtained. The operational effect of the first spacer 15 and the direct contact portion 19 between the mating surface 17 of the inner race 5 and the mating surface 18 of the washer 8 is substantially the same as the operational effect of the second spacer 16 and the direct contact portion 26 between the mating surface 24 of the inner race 5 and the mating surface 25 of the rear cover 10. Hereinafter, the operational effects obtained by the first spacer 15 and the direct contact portion 19 will be described as an example, and the operational effects obtained by the second spacer 16 and the direct contact portion 26 will not be described.

The outer diameter side of the mating surface 17 of the inner ring 5 and the mating surface 18 of the gasket 8 is sealed by the elastic seal member 21 of the first spacer 15. As shown in fig. 6, in a pressurized region D (for example, a lower region of the axle S) where a force F1 acts to narrow the gap between the mating surface 17 of the inner race 5 and the mating surface 18 of the washer 8 due to the deflection of the axle S during use, the elastic seal member 21 is compressively deformed. On the other hand, as shown in fig. 7, in a decompression region U of a force F2 in which the distance between the mating surface 17 of the inner race 5 and the mating surface 18 of the washer 8 is widened due to the deflection of the axle S during use (for example, in an upper region of the axle S), the elastic seal 21 is subjected to expansion deformation. By the compression deformation and the expansion deformation of the elastic seal 21, the outer diameter side of the mating surface 17 of the inner ring 5 and the mating surface 18 of the gasket 8 is always sealed. Thereby, even if abrasion powder due to frictional wear is generated between the mating surface 17 of the inner ring 5 and the mating surface 18 of the washer 8, the abrasion powder can be suppressed from entering the inside of the bearing.

Since the direct contact portion 19 is provided on the mating surface 17 of the inner ring 5 and the mating surface 18 of the washer 8, the inner ring 5 can be accurately positioned in the axial direction with respect to the axle S by the washer 8 at the time of assembly. At this time, the core 20 of the first spacer 15 is not in contact with the mating surface 17 of the inner ring 5 by the axial gap G1, and therefore, the positioning accuracy of the inner ring 5 by the direct contact portion 19 is not adversely affected. Here, since the gap between the mating surface 17 of the inner ring 5 and the mating surface 18 of the washer 8 is narrowed in the pressurized region D, the amount of pressurization in the pressurized region D increases from the inner diameter side toward the outer diameter side. On the other hand, in the pressure reduction region U, the gap between the mating surface 17 of the inner ring 5 and the mating surface 18 of the gasket 8 is made wider, and therefore the amount of pressure reduction in the pressure reduction region U increases from the inner diameter side toward the outer diameter side. In other words, the frictional wear tends to become larger on the outer diameter side and smaller on the inner diameter side. Therefore, by providing the direct contact portion 19 on the inner diameter side, the frictional wear on the direct contact portion 19 can be reduced.

As shown in fig. 6, in the pressurized region D in which the force F1 acts due to the deflection of the axle S during use, at least a part of the axial gap G1 is eliminated along with the compression deformation of the elastic seal 21. As a result, at least a part of the core bar 20 is in contact with both the mating surface 17 of the inner ring 5 and the mating surface 18 of the washer 8. By this contact of the core bar 20, the pressing force acting on the direct contact portion 19 can be dispersed to the core bar 20, and the pressing force acting on the direct contact portion 19 in the pressing region D can be made relatively small. Therefore, in use, the difference between the pressing force acting on the direct contact portion 19 in the decompression region U and the pressing force acting on the direct contact portion 19 in the pressurization region D can be reduced. Therefore, the repeated stress acting along with the rotation of the axle S can be reduced, and the frictional wear on the direct contact portion 19 can be more reliably suppressed. In other words, when the inner ring 5 is accurately positioned in the axial direction with respect to the axle S by the direct contact portion 19 at the time of assembly, even at the time of subsequent use, the frictional wear and the accompanying penetration of wear powder into the bearing interior can be reliably suppressed, and the axial accuracy of the rolling bearing 2 can be maintained over a long period of time, so that the life of the bearing device 1 can be sufficiently extended.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea thereof.

In the above-described embodiment, the case where the core 20 of the first spacer 15 includes the pair of first metal parts 22 that abut against the mating surfaces 18 provided on both the front and rear end sides of the washer 8 and have the axial gap G1 between the mating surfaces 17 of the inner ring 5, and the second metal part 23 that connects the outer diameter side end portions of the pair of first metal parts 22 and abuts against the outer peripheral surface 8a of the washer 8 has been exemplified, but the second metal part 23 may be divided into two parts in the axial direction as shown in fig. 8. Alternatively, as shown in fig. 9, the core member 20 of the first spacer 15 may be a plate-like member (for example, a circular plate-like member) formed only of the first metal part 22, with the second metal part 23 omitted. In the case of the embodiment illustrated in fig. 8 and 9, the first spacers 15 are attached to both front and rear end sides of the gasket 8.

In the above-described embodiment, the cases where the

cores

20 and 27 of the first spacer 15 and the second spacer 16 are in contact with the positioning members such as the washer 8 and the rear cover 10 and have the axial clearances G1 and G2 with the inner race 5 have been described, but the present invention is not limited to this. The

mandrels

20, 27 may also abut the inner ring 5 with an axial clearance to the positioning member.

In the above-described embodiment, the case where the axial recessed portion 18c is provided in the washer 8 and the axial protruding portion 22c that engages with the axial recessed portion 18c is provided in the core 20 of the first spacer 15 has been described as an example, but the axial recessed portion may be provided in the inner ring 5 and the axial protruding portion that engages with the axial recessed portion may be provided in the core 20 of the first spacer 15. Further, an axial convex portion may be provided on the core 27 of the second spacer 16, and an axial concave portion that engages with the axial convex portion may be provided on the rear cover 10. Alternatively, an axial recessed portion may be provided in the inner ring 5, and an axial protruding portion that engages with the axial recessed portion may be provided in the core 27 of the second spacer 16.

In the above-described embodiment, the case where the first spacer 15 is disposed between the inner ring 5 and the washer 8 and the second spacer 16 is disposed between the inner ring 5 and the rear cover 10 has been described as an example, but the spacer of the present invention may be disposed between the slinger 9 and the inner ring 5. In other words, the spacer of the present invention may be disposed at least one of between the inner ring 5 and the gasket 8, between the inner ring 5 and the rear cover 10, and between the inner ring 5 and the slinger 9 (between the inner ring 5 and the front cover 11 when the slinger 9 is omitted and the front cover 11 and the inner ring 5 are in direct contact). However, since the frictional wear tends to decrease toward the front end of the axle S, it is preferable to apply the spacer of the present invention only between the inner race 5 and the rear cover 10, or between the inner race 5 and the rear cover 10, and between the inner race 5 and the washer 8, from the viewpoint of suppressing the frictional wear.

In the above-described embodiment, the configuration in which the washer 8 is provided between the pair of inner rings 5 divided into two is exemplified as the inner ring, but the inner ring may be configured such that the washer 8 is omitted and the ends on the small diameter side of the pair of inner rings 5 are directly butted, or may be a single member in which the pair of inner rings 5 are integrated.

In the above-described embodiment, the tapered roller bearing is exemplified as the rolling bearing 2, but the present invention is not limited to this, and can be applied to other bearings such as a cylindrical roller bearing.

Claims

1. An axle bearing device comprising: a rolling bearing having an inner ring and an outer ring; a positioning member that is fitted to an outer peripheral surface of an axle and that positions the inner race in an axial direction with respect to the axle; and a spacer disposed between the mating surface of the inner race and the mating surface of the positioning member,

the bearing device for an axle is characterized in that,

the mating surface of the inner ring and the mating surface of the positioning member have direct contact portions that contact each other on the inner diameter side,

the spacer is provided with: a core bar that abuts either one of a mating surface of the inner ring or a mating surface of the positioning member on an outer diameter side of the direct contact portion, and that has an axial gap with the other; and an elastic seal member that seals between the mating surface of the inner ring and the mating surface of the positioning member at a position closer to an outer diameter side than the axial gap.

2. The bearing device for an axle according to claim 1,

either one of the mating surface of the inner ring and the mating surface of the positioning member includes an axial recessed portion at a position on an outer diameter side of the direct contact portion, and the core includes an axial protruding portion that engages with the axial recessed portion.

3. The bearing device for an axle according to claim 1 or 2,

the inner rings are arranged in a pair with a space in the axial direction,

the positioning member includes a washer disposed between the pair of inner rings with the spacer interposed therebetween, and having mating surfaces on both axial end sides to be joined to the inner rings.

4. The bearing device for an axle according to claim 3,

the core is provided with: a pair of first metal parts respectively disposed between a mating surface of one of the inner rings and a mating surface of the washer provided on one end side in the axial direction, and between a mating surface of the other of the inner rings and a mating surface of the washer provided on the other end side in the axial direction; and a second metal portion disposed on an outer peripheral surface of the gasket and connecting the pair of first metal portions.

5. The bearing device for an axle according to claim 4,

the first metal portion abuts against a mating surface of the washer, and has the axial gap between the first metal portion and the mating surface of the inner ring.

6. The bearing device for an axle according to any one of claims 1 to 5,

the positioning member includes a rear cover that is disposed on a rear end side in the axial direction of the inner ring with the spacer interposed therebetween, and that has a mating surface on a front end side in the axial direction that is joined to the inner ring.

7. The bearing device for an axle according to any one of claims 1 to 6,

the hardness of the core bar is lower than that of the inner ring.

8. The bearing device for an axle according to claim 7,

the core frame is made of cold-rolled steel plate, hot-rolled soft steel plate, high-tension steel plate, stainless steel plate, high-melting plated steel plate or brass plate.

9. The bearing device for an axle according to any one of claims 1 to 8,

the elastic sealing element is composed of nitrile rubber, acrylic rubber or fluororubber.