JP2013194880A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the amount of grease filled into a rolling bearing and obtain an enhancing effect in lubricating performance corresponding to the increased amount.SOLUTION: An outer ring 3 of a rolling bering includes a plurality of rows of raceway surfaces 3a, and an inside inner peripheral surface 3b positioned between the plurality of rows of raceway surfaces 3a. A peripheral groove 15 is formed in the inside inner peripheral surface 3b of the outer ring 3, and a large diameter portion 13 is formed by a groove bottom surface 15a of the peripheral groove 15. An inner periphery of the outer ring 3 in a direction with the peripheral groove 15 extending is provided with a small diameter portion 14 having a smaller diameter than the large diameter portion 13 and smoothly connected to the large diameter portion 13.

Description

  The present invention relates to a rolling bearing, for example, a rolling bearing used for supporting an axle of a railway vehicle.

  As a bearing for supporting an axle of a railway vehicle, a double-row tapered roller bearing combined with a back surface is widely used. A rolling bearing 31 shown in FIG. 6 is a double-row tapered roller bearing of this back combination.

  The rolling bearing 31 includes an outer ring 32 having a conical raceway surface, an inner ring 33 having a conical raceway surface, a tapered roller 34, and a seal device 35 as main components. Grease is sealed in the space between the inner peripheral surface of the outer ring 32 and the outer peripheral surface of the inner ring 33 (the inner space of the bearing). Leakage of grease or intrusion of foreign matter is caused by the inner shaft of the outer ring 32. This is prevented by the sealing devices 35 mounted on both sides in the direction. The outer ring 32 is fixed to the axle box on the vehicle side, and the inner ring 33 is fixed to the axle 36.

  In this type of double-row tapered roller bearing, the inner ring 33 rotates together with the axle 36 during use. Due to the centrifugal force generated at that time, the grease tends to be pushed in on both sides in the axial direction and stay in the vicinity of the sealing device 35. For this reason, if no countermeasure is taken, the ratio of the enclosed grease that contributes to lubrication of the rotating portion of the bearing 31 decreases, leading to a decrease in bearing life and a shortened maintenance cycle.

  As a countermeasure against such a problem, it is conceivable to increase the amount of grease enclosed in the internal space of the bearing 31. As a configuration of the bearing for this purpose, for example, Patent Document 1 discloses that an annular recess 37 is provided on the inner diameter surface of the central portion of the outer ring 32 as shown in FIG.

JP 7-301244 A

  By the way, when such an annular recess 37 is provided in the outer ring 32, grease accumulates in the annular recess 37. As shown in FIG. 6, in a state where the bearing 31 supports the axle 36, the base oil separated from the grease adhering in the annular recess 37 flows down in the annular recess 37 due to the influence of gravity, and is below the annular recess 37. Accumulate. However, since the side surfaces on both sides of the annular recess 37 provided in the outer ring 32 extend in the radial direction, the base oil accumulated on the lower side of the annular recess 37 cannot get over the side surface, and the raceway surface. It is hard to be supplied. Therefore, even if the amount of grease that can be held in the internal space of the bearing by the annular recess 37 can be increased, it is not possible to obtain an effect of improving the lubricating performance commensurate with the increase in grease.

  In view of the above circumstances, an object of the present invention is to obtain an effect of improving the lubricating performance commensurate with the increase amount while increasing the amount of grease enclosed in the rolling bearing.

  A rolling bearing according to the present invention for solving the above-mentioned problems includes a double-row raceway surface, a fixed-side outer ring having an inner inner circumferential surface located between the double-row raceway surfaces, and a double-side raceway surface facing the raceway surface of the outer ring. In a rolling bearing provided with an inner ring on the rotation side having a raceway surface in a row, a double row rolling element disposed between raceway surfaces of the outer ring and the inner ring, and grease sealed in a space between the outer ring and the inner ring, A circumferential groove is provided on the inner inner circumferential surface of the outer ring, a large-diameter portion is formed at the groove bottom surface of the circumferential groove, and the outer ring inner circumference in the direction in which the circumferential groove extends has a smaller diameter and a larger diameter than the large-diameter portion. A small diameter part smoothly connected to the part is provided.

  Here, the large-diameter portion and the small-diameter portion mean that the distance from the axis of the rolling bearing is large or small.

  In the above configuration, the large-diameter portion formed at the groove bottom surface of the circumferential groove forms a recess with respect to the inner inner circumferential surface of the outer ring, so that compared with the case where there is no circumferential groove on the inner inner circumferential surface. The amount of grease that can be sealed in the rolling bearing is increased by the circumferential groove capacity.

  During operation of the bearing, lubricating grease accumulates in the circumferential groove due to the centrifugal force, and the base oil separates from the accumulated grease. By providing a small-diameter portion that is smaller in diameter than the large-diameter portion and smoothly connected to the large-diameter portion on the inner periphery of the outer ring in the direction in which the circumferential groove extends, the base oil is provided in the small-diameter portion at the boundary between the small-diameter portion and the internal inner peripheral surface. The step which becomes an obstacle when shifting from the inner peripheral surface to the inner peripheral surface becomes smaller or disappears. Therefore, the base oil that has reached the small diameter portion is easily supplied to the outer ring raceway surface via the inner peripheral surface, and the ratio of lubricating grease that contributes to lubrication on the raceway surface is increased. Accordingly, it is possible to increase the amount of grease enclosed in the rolling bearing while obtaining an effect of improving the lubricating performance commensurate with the increased amount.

  In the above configuration, the small-diameter portion can be formed to have a larger diameter than the inner inner peripheral surface, the same diameter as the inner inner peripheral surface, or a smaller diameter than the inner inner peripheral surface. Normally, the supply of the base oil that has reached the small diameter portion to the outer ring raceway surface becomes smoother in the order listed above.

  When the small-diameter portion is formed to have a smaller diameter than the inner inner peripheral surface, it is desirable to form both sides in the axial direction of the small-diameter portion into an inclined surface shape in which the axial distance between them increases on the outer diameter side. Thereby, the supply of the base oil reaching the small diameter portion to the outer ring raceway surface becomes smoother.

  The small diameter portion of the inner periphery of the outer ring can be formed by, for example, decentering the circumferential groove with respect to the axis.

  Moreover, a small diameter part can also be comprised by the internal peripheral surface of another member attached to the outer ring | wheel. If it is this structure, the form of a small diameter part can be changed by changing the shape and dimension of another member, and a design change will become easy. In this case, if the circumferential groove is formed in an annular shape coaxial with the axis, and the separate member is attached to the circumferential groove, the circumferential groove can be accurately formed at low cost.

  If the oil repellent coating is formed on at least the small diameter portion in any of the above configurations, the base oil reaching the small diameter portion is repelled by the coating, so that the base oil is more smoothly supplied from the small diameter portion to the outer ring raceway surface. .

  In any one of the above-described configurations, if an indication for identifying one or both of the small-diameter portion and the large-diameter portion is provided on the end surface of the outer ring, the operator fixes the outer ring to the housing. At this time, it is easy to assemble the bearing device with the small diameter portion facing down by visually recognizing the display.

  In any one of the above-described configurations, in order to prevent breakage of the outer ring due to excessive carburization when carburizing and quenching, it is desirable that the minimum thickness of the outer ring in the large diameter portion be 3% or more of the outer diameter dimension of the outer ring. .

  In any one of the configurations described above, it is desirable that the outer ring is fixed to the housing with the small diameter portion facing down. With this configuration, the base oil separated from the grease accumulated in the large diameter portion gathers in the small diameter portion due to gravity, so the amount of base oil supplied from the small diameter portion to the outer ring raceway surface increases.

  If it is a rolling stock axle bearing device which has a rolling bearing of one of the above-mentioned composition, it can enjoy the above-mentioned effect corresponding to a rolling bearing of each composition.

  According to the present invention, the amount of grease that can be enclosed in the rolling bearing is increased by the capacity of the circumferential groove. Further, since the base oil separated from the grease is easily supplied from the small diameter portion to the outer ring raceway surface during the operation of the bearing, the lubricity of the bearing is improved. As a result, while increasing the amount of grease enclosed in the rolling bearing, it is possible to obtain an effect of improving the lubrication performance commensurate with the increased amount, thereby achieving an increase in the bearing life of the rolling bearing, an extension of the maintenance cycle, and the like. It becomes possible.

It is an axial sectional view of the rolling bearing according to the first embodiment of the present invention. It is sectional drawing which shows the outer ring | wheel of the rolling bearing which concerns on 1st Embodiment of this invention, Comprising: (A) is axial sectional drawing, (B) is radial sectional drawing (AA sectional view taken on the line AA). It is. It is sectional drawing which shows the outer ring | wheel of the rolling bearing which concerns on 2nd Embodiment of this invention, Comprising: (A) is axial sectional drawing, (B) is radial sectional drawing (BB sectional drawing of (A)). It is. It is sectional drawing which shows the outer ring | wheel of the rolling bearing which concerns on 3rd Embodiment of this invention, Comprising: (A) is axial direction sectional drawing, (B) is radial direction sectional drawing (CC sectional view taken on the line of (A)). It is. It is sectional drawing which shows the modification of 1st Embodiment of this invention, Comprising: (A) is an axial sectional view of an outer ring | wheel, (B) is the radial sectional view (DD sectional view taken on the line of (A)). It is. It is an axial sectional view of a conventional rolling bearing.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows a rolling bearing 1 according to a first embodiment of the present invention. The rolling bearing 1 supports an axle 2 of a railway vehicle, and FIG. 1 illustrates a double-row tapered roller bearing in a rear combination. The rolling bearing 1 includes an outer ring 3, an inner ring 4, a plurality of tapered rollers 5 as rolling elements, a cage 6, and a seal device 7 as main components. The rolling bearing 1 and the axle 2 constitute a railway vehicle axle bearing device.

  On the inner peripheral surface of the outer ring 3, a double row conical raceway surface 3a and an inner inner peripheral surface 3b provided between the double row raceway surfaces 3a are provided coaxially. The inner diameter end of the conical track surface 3a and the axial end of the inner inner peripheral surface 3b have the same inner diameter dimension. The inner ring 4 has a double-row conical raceway surface 4a on the outer peripheral surface, and is divided for each raceway surface 4a. The tapered roller 5 is movably interposed between the raceway surface 3a of the outer ring 3 and the raceway surface 4a of the inner ring 4 which face each other. In each roller row of tapered rollers 5 arranged in a double row, each tapered roller 5 is held by a cage 6 at equal intervals in the circumferential direction. A space formed between the outer ring 3 and the inner ring 4 (inner space of the rolling bearing 1) is filled with a lubricant such as grease, and the sealing device 7 seals this space at both ends in the axial direction. The seal device 7 is constituted by, for example, a seal case 7a press-fitted into the outer ring and a seal member having a seal lip (not shown). The seal device 7 constitutes a contact seal with the oil drainer 8.

  The outer ring 3 is fixed to an axle box 9 of a railway vehicle having an outer peripheral surface 3c as a housing. The divided inner ring 4 is externally fitted to the axle 2 together with a spacer 10 disposed therebetween and oil drains 8 disposed on both sides in the axial direction. These members are clamped and fixed between the lid member 11 and the shoulder portion 2 a of the axle 2 by fastening the lid member 11 to the front end side of the axle 2 with a bolt 12.

  As shown in FIG. 2B, the inner peripheral surface 3b of the outer ring 3 has a large diameter portion 13 larger in diameter than the inner inner peripheral surface 3b and a smaller diameter than the large diameter portion 13, and the large diameter portion 13 And a small-diameter portion 14 that is formed at a 180 ° -opposing position and is smoothly connected to the large-diameter portion 13. Here, the large diameter portion 13 and the small diameter portion 14 mean that the distance from the axis O of the rolling bearing 1 is a large diameter and a small diameter. The outer ring 3 is fixed to the axle box 9 so that the small diameter portion 14 is positioned at the lowermost end and the large diameter portion 13 is positioned at the uppermost end.

  As shown in FIG. 2B, a circumferential groove 15 with ends is provided on the inner inner peripheral surface 3 b of the outer ring 3. The groove bottom surface 15 a of the circumferential groove 15 has a perfect circular cross section, and the center thereof is eccentric upward with respect to the axis O. Therefore, the groove depth of the circumferential groove 15 is the largest at the uppermost end and becomes shallower toward the lower side. At the lowest end, the groove depth of the circumferential groove 15 is 0, and both circumferential ends of the circumferential groove 15 are smoothly connected to the inner inner peripheral surface 3b. The peripheral region including the uppermost end of the bottom surface 15 a of the circumferential groove 15 constitutes the large diameter portion 13, and the inner inner circumferential surface 3 b between the circumferential ends of the circumferential groove 15 constitutes the small diameter portion 14.

  As shown in FIG. 2A, the circumferential groove 15 includes a bottom surface 15a and two side surfaces 15b on both sides in the axial direction. The side surface 15b is formed in an inclined shape in which the distance between both side surfaces 15b increases on the inner diameter side.

  The minimum thickness of the outer ring 3 in the large-diameter portion 13 is 3% or more of the outer diameter dimension of the outer ring. Thereby, even when carburizing and quenching is performed at the time of manufacturing the outer ring 3, it is possible to suppress breakage of the outer ring 3 due to excessive carburization. Such a configuration is particularly beneficial when the outer ring 3 is formed of case-hardened steel.

  Although not shown, the end face 3d of the outer ring 3 is used to identify the position of one or both of the large-diameter portion 13 (particularly the portion having the maximum groove depth) and the small-diameter portion 14. A display is provided. If such a display is formed on the end surface 3d at the stage of manufacturing the outer ring 3, the operator can visually recognize the display when attaching the outer ring 3 to the axle box 9, so that the large-diameter portion 13 is at the maximum. It becomes easy to arrange | position at the upper end and arrange | position the small diameter part 14 to the lowest end, and workability | operativity at the time of an assembly increases. As an example of this display, for example, an identification display such as a circular shape or a wedge shape may be engraved on the outer ring end surface 3d.

  The rolling bearing 1 configured as described above can enjoy the following effects.

  During operation of the rolling bearing 1, grease is collected in the circumferential groove 15 by centrifugal force, and the base oil is separated from the accumulated grease. In the separated base oil, the small-diameter portion 14 is formed in the extending direction of the circumferential groove 15, the large-diameter portion 13 and the small-diameter portion 14 are smoothly connected via the circumferential groove 15, and the small-diameter portion Since the outer ring 3 is fixed to the axle box 9 so that 14 is positioned on the lower side, the outer ring 3 flows downward in the circumferential groove 15 due to the action of gravity and shifts to the small diameter portion 14.

  In the rolling bearing of this embodiment, unlike the rolling bearing 31 described in FIG. 6, there are no steps on both axial sides of the small diameter portion 14. For this reason, the base oil that has flowed down the circumferential groove 15 and reached the small diameter portion 14 smoothly transitions to the raceway surface 3a of the outer ring 3 via the inner inner peripheral surface 3b. The base oil that has reached the outer ring raceway surface 3 a reaches the entire outer ring raceway surface 3 a by the rolling of the tapered rollers 5.

  Thus, since the base oil is smoothly supplied to the raceway surface 3a of the outer ring 3 around the small diameter portion 14 and the periphery thereof, the supply amount of the base oil to the raceway surface 3a of the outer ring 3 can be increased. Therefore, abundant base oil can be supplied to the raceway surface 3a, and the lubrication performance of the bearing is improved.

  In addition, since the concave portion is formed in the inner inner peripheral surface 3b by forming the circumferential groove 15, the rolling is performed by the capacity of the large diameter portion 13 as compared with the case where the circumferential groove is not present in the inner inner peripheral surface 3b. The amount of grease that can be sealed in the bearing 1 increases. Accordingly, it is possible to obtain an effect of improving the lubricating performance commensurate with the increase amount while increasing the amount of grease sealed in the rolling bearing 1.

  In the above description, the case where the circumferential groove 15 is an end and the small diameter portion 14 is formed to have the same diameter as the inner inner peripheral surface 3b is illustrated. However, as shown in FIGS. The circumferential groove 15 eccentric with respect to the center O may be formed in an annular shape. In this case, the depth of the circumferential groove 15 with respect to the inner inner peripheral surface 3b is maximum at the uppermost end and minimum at the lowermost end. Accordingly, the large-diameter portion 13 is formed in the circumferential peripheral region including the uppermost end of the groove bottom surface 15a of the circumferential groove 15, and the small-diameter portion 14 is formed in the circumferential peripheral region including the lowermost end of the groove bottom surface 15a. Is done. Even in this case, the level difference between the groove bottom surface 15a and the inner inner peripheral surface 3b in the small diameter portion 14 is reduced, so that the base oil collected in the small diameter portion 14 can be smoothly transferred to the outer ring raceway surface 3a through the inner inner peripheral surface 3b. Can be migrated.

  In this configuration, in order to more smoothly move the base oil from the small diameter portion 14 to the inner inner peripheral surface 3b, the both side surfaces 15b of the circumferential groove 15 are formed in the small diameter portion 14 as shown in FIG. It is desirable that the inner diameter side be formed in an inclined surface shape in which the axial distance between them is increased.

  FIG. 3 shows the outer ring 3 of the rolling bearing 1 according to the second embodiment of the present invention. In the first embodiment shown in FIGS. 2 (A) and 2 (B), the small-diameter portion 14 is formed to have the same diameter as the inner inner peripheral surface 3b or larger diameter than the inner inner peripheral surface 3b, but this second embodiment. Then, the small diameter part 14 is formed in a smaller diameter than the internal inner peripheral surface 3b.

  Also in the second embodiment, as shown in FIG. 3 (B), an end circumferential groove 15 that is eccentric to the upper side with respect to the axis O of the outer ring 3 (bearing 1) is formed on the inner peripheral surface 3b of the outer ring 3. Is provided.

  Between both ends in the circumferential direction of the circumferential groove 15, a partial area in the axial direction (the central area in the drawing) of the inner inner peripheral surface 3 b protrudes toward the inner diameter side with a certain width in the circumferential direction, and is a protrusion that is integral with the outer ring 3. 16 is constituted. The inner peripheral surface of the projecting portion 16 has an arcuate cross section in which the center is decentered above the axis O and the radius of curvature is larger than the radius of curvature of the inner inner peripheral surface 3b. Therefore, the protruding width of the inner peripheral surface of the protruding portion 16 from the inner inner peripheral surface 3b gradually increases downward, and is the largest at the lowermost end. Even in this configuration, the circumferential peripheral region including the uppermost end of the bottom surface 15 a of the circumferential groove 15 constitutes the large-diameter portion 13, and the circumferential peripheral region including the lowermost end of the inner peripheral surface of the protruding portion 16 has a small diameter. Part 14 is configured. Both ends of the bottom surface 15a of the circumferential groove 15 are smoothly connected to the inner peripheral surface of the protruding portion 16, and for this reason, there is a level difference in the region from the large diameter portion 13 to the small diameter portion 14 that inhibits the flow of the base oil. It is not formed, and the base oil can smoothly transition to the small diameter portion 14.

  Further, as shown in FIG. 3A, both sides in the axial direction of the protruding portion 16 are formed in a mountain shape over the entire length in the circumferential direction, and the axial distance between the both sides in the axial direction sandwiching the top is on the outer diameter side. It is comprised by the inclined surface 16a expanded by. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  In the present embodiment, the small-diameter portion 14 protrudes from the inner inner peripheral surface 3b to the inner diameter side, and is located on the inner diameter side from the raceway surface 3a of the outer ring 3 at the same circumferential position. Therefore, the base oil that has flowed into the small diameter portion 14 is more likely to flow into the raceway surface 3 a of the outer ring 3. This flow of the base oil is further smoothed because the both sides in the axial direction of the small diameter portion 14 are constituted by the inclined surfaces 16a.

  In FIG. 4, the outer ring | wheel 3 of the rolling bearing 1 which concerns on 3rd Embodiment of this invention is shown. In this embodiment, as shown in FIG. 4 (B), unlike the second embodiment shown in FIGS. 3 (A) and 3 (B), the protruding portion 16 is formed by a member 17 different from the outer ring 3.

  More specifically, the inner circumferential surface 3b of the outer ring 3 is provided with a circumferential groove 15 that is coaxial with the inner inner circumferential surface 3b and has a larger diameter than the inner inner circumferential surface 3b. The depth of the circumferential groove 15 with respect to the inner inner peripheral surface 3b is constant. Further, both side surfaces 15b of the circumferential groove 15 are surfaces extending in the radial direction. A rear member 17 separate from the outer ring is attached to the lower end of the circumferential groove 15 by means such as press fitting. The retrofitting member 17 is a thin arc-shaped member extending in the circumferential direction, and the outer peripheral surface thereof is formed in an arc surface shape having the same curvature as the groove bottom surface 15 a of the circumferential groove 15. The inner peripheral surface of the retrofit member 17 has an arcuate surface shape that is eccentric upward with respect to the axis O, and the radius of curvature thereof is larger than the radius of curvature of the outer peripheral surface. Therefore, the protrusion width from the inner inner peripheral surface 3b of the protrusion 16 gradually increases downward, and is maximum at the lowermost end. In the above configuration, the circumferential peripheral region including the uppermost end of the groove bottom surface 15 a of the circumferential groove 15 constitutes the large diameter portion 13, and the lowermost end of the inner peripheral surface of the retrofitting member 17 is included. A partial region in the circumferential direction constitutes the small diameter portion 14.

  Both ends in the circumferential direction of the retrofitting member 17 are inclined surfaces 17 a, and the inclined surfaces 17 a are smoothly connected to the groove bottom surface 15 a of the circumferential groove 15 and the inner peripheral surface of the retrofitting member 17. Therefore, the flow of the base oil from the large diameter portion 13 to the small diameter portion 14 is not hindered.

  In this embodiment, since the circumferential groove 15 is formed coaxially with the inner inner peripheral surface 3b, centering is easy even when the circumferential groove 15 is machined by turning or the like, and the circumferential groove 15 is machined. Accuracy can be increased. Moreover, the shape of the small diameter part 14 can be easily changed by changing the shape of the retrofit member 17, and it becomes possible to easily cope with a design change. Since other configurations are the same as those in the second embodiment, the description thereof is omitted.

  In each of the embodiments described above, it is desirable to form an oil repellent film made of PTFE or the like on the small diameter portion 14. By forming the oil-repellent coating on the small-diameter portion 14 in this way, the base oil that has moved to the small-diameter portion 14 is subjected to an oil-repellent action, so that it easily shifts to the inner inner peripheral surface 3b and further to the outer ring raceway surface 3a. The oil-repellent coating is formed only in the vicinity of the lowermost end of the inner peripheral surface of the outer ring 3, and is the direction in which the circumferential groove 15 extends and the lower half of the inner peripheral surface of the outer ring 3 (FIG. 5). May be formed in the entire region from the circumferential position immediately below the vertical direction of the axis O exemplified by the double arrow X to 90 ° on both sides.

  In each of the above embodiments, the rolling bearing 1 used for supporting the axle 2 of the railway vehicle has been exemplified. However, the rolling bearing of the present invention is not limited to this, and for example, in general industrial equipment including a rolling mill. It can be widely used for supporting the rotating shaft. Moreover, in the said embodiment, although the double row tapered roller bearing was illustrated as a bearing type of the rolling bearing 1, it is also about other bearing types, for example, rolling bearings, such as a double row cylindrical roller bearing and a double row ball bearing. The present invention can be applied.

DESCRIPTION OF SYMBOLS 1 Rolling bearing 2 Axle 3 Outer ring 3a Track surface 3b Inner inner peripheral surface 3c Outer peripheral surface 3d End surface 4 Inner ring 4a Track surface 5 Roller (rolling element)
13 Large-diameter portion 14 Small-diameter portion 15 Circumferential groove 15a Bottom surface 15b Side surface 16 Projection portion 17 Separate member O Axis center

Claims (9)

A fixed-side outer ring having a double-row raceway surface and an inner inner circumferential surface located between the double-row raceway surfaces; a rotary-side inner ring having a double-row raceway surface facing the raceway surface of the outer ring; and an outer ring; In a rolling bearing provided with double row rolling elements arranged between raceways of the inner ring and grease sealed in a space between the outer ring and the inner ring,
A circumferential groove is provided on the inner inner circumferential surface of the outer ring, a large-diameter portion is formed at the groove bottom surface of the circumferential groove, and the outer ring inner circumference in the direction in which the circumferential groove extends has a smaller diameter and a larger diameter than the large-diameter portion. A rolling bearing characterized by providing a small-diameter part smoothly connected to the part.   The rolling bearing according to claim 1, wherein the small-diameter portion is formed to have a larger diameter than the inner peripheral surface.   The rolling bearing according to claim 1, wherein the small-diameter portion is formed to have the same diameter as the inner inner peripheral surface.   The rolling bearing according to claim 1, wherein the small-diameter portion is formed to have a smaller diameter than the inner peripheral surface.   The rolling bearing according to claim 4, wherein both sides in the axial direction of the small-diameter portion are formed in an inclined surface shape in which an axial distance between them is enlarged on the outer diameter side.   The rolling bearing according to claim 1, wherein the circumferential groove is formed eccentrically with respect to an axis.   The rolling bearing according to any one of claims 1 to 6, wherein the small-diameter portion is configured by an inner peripheral surface of another member attached to the outer ring.   The rolling bearing according to any one of claims 1 to 7, wherein an indication for identifying one or both circumferential positions of the small diameter portion or the large diameter portion is provided on an end surface of the outer ring.   A railcar axle bearing device comprising the rolling bearing according to any one of claims 1 to 8.

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