Roller bearing

Abstract

To provide a roller bearing capable of increasing load capacity and reducing man-hours of assembling work.SOLUTION: The roller bearing includes an inner ring, an outer ring, a plurality of rollers interposed between the inner ring and the outer ring, and a cage formed with pockets Pt for holding the rollers. The cage has a plurality of cage segments 6 divided in the circumferential direction. The holder segment 6 has a pair of side plates 7, 7 opposed to each other in the axial direction, and a plurality of column parts 8 installed over these side plates 7, 7 on the outer diameter side and extending in the axial direction along a surface of the roller, and a pocket Pt is constituted of the pair of side plates 7, 7 and the plurality of column parts 8. The respective pillar parts 8 are arranged on the outer diameter side more than a pitch circle diameter of the roller. Engaging parts 9 projecting inward in the axial direction and opposed to each other in the axial direction are provided on the 7a part of the inside surface of each side plate 7. An engaged part rotatably engaged with the engaging part 9 is arranged in a central part in both end surfaces in the axial direction of the roller.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a roller bearing, and more particularly to a technique applied to a large roller bearing for use in, for example, a main shaft in a wind power generator. [Background technology]

[0002] Due to dimensional restrictions on the workpieces in processing equipment and transportation issues, it is not easy to manufacture a one-piece cage for a large roller bearing used in, for example, a wind power generator. Therefore, instead of a one-piece cage, a resin segment cage separated in the circumferential direction is often used.

[0003] Resin segment cages solve the manufacturing problems of the one-piece cages mentioned above and offer manufacturing cost advantages over machining metal cages. However, to ensure sufficient strength for each segment cage, the cage wall thickness (pillar width) tends to be large, which can limit the diameter and number of rollers that can be accommodated in the bearing. In this case, the load capacity of the bearing may be smaller than that of bearings using one-piece cages. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent Application Publication No. 116428280 Summary of the Invention [Problem to be solved by the invention]

[0005] (1) In the prior art, a segmented cage in which a single pocket is formed (hereinafter referred to as a "single-pocket segmented cage") is disclosed (Patent Document 1). In this single-pocket segmented cage, as shown in FIG. 11, pillars 82 of a cage 81 that maintain the spacing between rollers 80 are provided at the roller pitch diameter of the bearing. In this case, the diameter and number of rollers 80 are limited by the circumferential thickness of the pillars 82 (pillar width of the cage 81), which also limits the load capacity of the bearing. The issue of limiting the load capacity of the bearing by ensuring the circumferential thickness of the pillars 82 of the cage 81 also arises in a one-piece cage. However, in a single-pocket segmented cage, sufficient strength must be ensured in each segment, which has a greater impact on the bearing load capacity than a one-piece cage.

[0006] (2) In the case of a one-piece cage, the pillars may be arranged so as not to overlap the pitch diameter of the rollers. However, in the case of a single-pocket segment cage, if the pillars of the cage are arranged on the outer diameter side, for example, so as not to overlap the pitch diameter of the rollers, the following problems arise. For example, when a bearing is used on a horizontal shaft, gravity causes the cage on the lower side of the bearing to fall toward the outer ring. This causes the cage to lose its function of guiding the rollers, and contact between the rolling surfaces of adjacent rollers may occur during use. Because the rollers rotate during use, the rolling surfaces of adjacent rollers are subjected to relatively opposite peripheral velocities, causing them to come into contact. This can lead to surface abnormalities such as smearing on the roller rolling surfaces.

[0007] (3) It is also possible to position the pillars of the single-pocket segment cage on the outer diameter side so that they do not interfere with the pitch diameter of the rollers, and to provide a guide surface with the outer ring, thereby creating an outer ring guide type. In this case, if the guide surface is not sufficiently lubricated, it may wear out. In addition, the sliding resistance of the guide surface may cause the bearing torque and heat generation to increase.

[0008] (4) Furthermore, single-pocket segment cages can freely rotate around the axis of the rollers. Therefore, when assembling the cage and roller bearing, it is necessary to always pay attention to the orientation of the cage and place a large number of cages on the raceway ring while making sure that the cage is maintained in the specified direction. Therefore, the assembly work requires a lot of labor, which leads to a decrease in work efficiency.

[0009] An object of the present invention is to provide a roller bearing that can increase the load capacity and reduce the number of assembly steps. [Means for solving the problem]

[0010] The roller bearing of the present invention comprises an inner ring, an outer ring, a plurality of rollers interposed between the inner ring and the outer ring, and a cage formed with pockets for holding the rollers, the cage being made up of a plurality of cage segments arranged in the circumferential direction, The cage segment has a pair of side plates facing each other in the axial direction and a plurality of pillar portions extending parallel to the axial direction and spanning the pair of side plates, the pair of side plates and the plurality of pillar portions defining the pockets, Each of the pillar portions is provided on the outer diameter side of the pitch circle diameter of the roller, An inner surface of each of the side plates is provided with engaging portions that protrude inward in the axial direction or are recessed outward in the axial direction and are opposed to each other in the axial direction, The roller has an engaged portion at the center of each of its axial end surfaces, which is rotatably engaged with the engaging portion.

[0011] With this configuration, the bar portions of the cage segments are located on the outer diameter side of the pitch circle diameter of the rollers. Therefore, restrictions on the roller diameter and number of rollers imposed by the circumferential thickness of the bar portions can be relaxed compared to conventional segment cages. This allows the load capacity of the roller bearing to be greater than that of roller bearings equipped with conventional segment cages.

[0012] The rollers have engaged portions at the center of both axial end faces that rotatably engage with the engaging portions on the inner surfaces of the side plates. This makes it possible to limit movement of the cage segments toward the outer diameter. This prevents the cage segments from falling toward the outer ring even if the cage is not outer ring guided and the cage posts are positioned on the outer diameter side so as not to interfere with the pitch circle diameter of the rollers. This prevents the loss of the roller guiding function.

[0013] Furthermore, the cage segments have a pair of side plates that face each other in the axial direction. Therefore, the inner diameter portions of the side plates are restricted by the inner ring. This can limit rotation of the cage segments around the roller axes. Therefore, when assembling the cage segments into the roller bearing, the cage segments can be maintained in a predetermined orientation without requiring special care. This reduces the number of steps in the assembly process.

[0014] The engaging portions may be spherical protrusions that protrude axially inward from the inner surfaces of the side plates, and the engaged portions of the rollers may be concave spherical recesses that engage with the spherical protrusions. In this way, by engaging the concave spherical recesses with the spherical protrusions, it is possible to reduce wear due to sliding between them.

[0015] The inner ring may have a raceway surface on which the rollers roll and ribs provided on both axial sides of the raceway surface, and each side plate may have an inner diameter surface facing the radially opposing ribs with a predetermined radial gap δ1 between them. The determined radial gap δ1 is a gap that is arbitrarily determined by design or the like, and is determined by obtaining an appropriate gap, for example, through testing and / or simulation.

[0016] This configuration makes it possible to avoid contact between the inner diameter surface of the side plate and the flange of the inner ring while the roller bearing is in use, thereby preventing wear on the inner diameter surface of the side plate and the flange of the inner ring, as well as increases in torque and heat generation, and improving the performance and reliability of the roller bearing.

[0017] It is more preferable that the radial gap δ2 between the engaging portion of the side plate and the engaged portion be smaller than the radial gap δ1 between the inner diameter surface of the side plate and the rib portion. In this case, the radial movement of the cage relative to the rollers is limited, and contact between the inner diameter surface of the side plate and the rib portion of the inner ring can be more reliably avoided.

[0018] The cage segments may be made of a resin material, which can reduce manufacturing costs compared to machining a metal cage. [Effects of the Invention]

[0019] The roller bearing of the present invention comprises an inner ring, an outer ring, a plurality of rollers interposed between the inner ring and the outer ring, and a cage formed with pockets for holding the rollers, the cage being made up of a plurality of cage segments arranged circumferentially, the cage segments having a pair of side plates facing each other in the axial direction and a plurality of pillars extending parallel to the axial direction and spanning the pair of side plates, the pair of side plates and the plurality of pillars forming the pockets, each of the pillars being located on the outer diameter side of the pitch circle diameter of the rollers, the inner surfaces of the side plates being provided with engaging portions that project axially inward or are recessed axially outward and face each other in the axial direction, and the rollers being provided with engaged portions at the centres of both axial end faces that rotatably engage with the engaging portions. This makes it possible to increase the load capacity compared to conventional structures and reduce the number of assembly steps. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a vertical cross-sectional view of a roller bearing according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view partially showing a part of the roller bearing. [Figure 3] FIG. 2 is a perspective view of a retainer segment and rollers of the roller bearing. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 2 is an enlarged cross-sectional view of a main portion of the cage segment and rollers. [Figure 7] FIG. 7 is a partially enlarged view of a part of FIG. 6. [Figure 8] FIG. 10 is a perspective view of a cage segment and rollers of a roller bearing according to a second embodiment of the present invention. [Figure 9A] FIG. 10 is an enlarged cross-sectional view of a main portion of a roller bearing according to a third embodiment of the present invention. [Figure 9B] FIG. 10 is an enlarged cross-sectional view of a main portion of a roller bearing according to a fourth embodiment of the present invention. [Figure 10] FIG. 1 is a cutaway perspective view of a wind turbine generator using a roller bearing according to any one of the embodiments of the present invention. [Figure 11] FIG. 10 is a perspective view showing an inner ring assembly including an inner ring, a cage segment, and rollers in a conventional roller bearing. DETAILED DESCRIPTION OF THE INVENTION

[0021] [First embodiment] A roller bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 7. The roller bearing is a large tapered roller bearing used, for example, to support the main shaft of a wind turbine generator. In the case of a large tapered roller bearing, for example, the average diameter of the tapered rollers is 40 mm or more, and the outer diameter of the roller bearing is 1 m or more. However, roller bearings are not limited to use in wind turbine generators, and can be applied to a variety of machines, devices, etc. The roller bearing can also be applied to small and medium-sized roller bearings.

[0022] <Overall structure of a roller bearing> FIG. 1 is a cross section (longitudinal cross section) of a roller bearing, a tapered roller bearing 1, taken along a plane including the axial direction. Tapered roller bearing 1 comprises an inner ring 2, an outer ring 3, a plurality of rollers 4 interposed between the inner ring 2 and the outer ring 3, and a cage 5 formed with pockets Pt for holding the rollers 4. The bearing space between the inner and outer rings 2, 3 is filled with, for example, grease as a lubricant. The rollers 4 are tapered rollers. In this specification, tapered rollers may sometimes be simply referred to as "rollers".

[0023] The outer ring 3 has, on its inner circumference, a raceway 3a on which the tapered rollers 4 roll. The inner ring 2 has, on its outer circumference, a raceway 2a on which the tapered rollers 4 roll, and a large rib portion 2b and a small rib portion 2c provided on both axial sides of the raceway surface 2a. The large end faces of the tapered rollers 4 contact the large rib portion 2b of the inner ring 2, and the small end faces of the tapered rollers 4 contact the small rib portion 2c of the inner ring 2.

[0024] In this specification, a roller bearing may be simply referred to as a "bearing." In the following description, the direction of the bearing center axis AX, which is the bearing shaft center, is referred to as the "axial direction," the direction perpendicular to the bearing center axis AX is referred to as the "radial direction," and the direction around the bearing center axis AX is referred to as the "circumferential direction." In addition, the side facing the bearing center axis AX is referred to as the "inner diameter side," and the side away from the bearing center axis AX is referred to as the "outer diameter side."

[0025] <Cage segment> As shown in FIG. 2, the cage 5 has a plurality of cage segments 6 divided in the circumferential direction. In other words, the cage 5 is made up of a plurality of cage segments 6 arranged in the circumferential direction. The cage segments 6 are made of a resin material. For example, the cage segments 6 are made of polyetheretherketone blended with carbon fiber or polyetheretherketone blended with glass fiber. However, the material of the cage segments 6 is not limited to these. The resin cage segments 6 can be processed by, for example, injection molding. The cage segments 6 may also be formed by a combination of injection molding and machining.

[0026] As shown in Figure 3, the cage segment 6 in this example is a single-pocket segment cage in which a single pocket Pt is formed. As shown in Figure 4, the cage segment 6 has a pair of side plates 7, 7 and multiple (one pair in this example) pillar portions 8. The pair of side plates 7, 7 face each other in the axial direction. Each side plate 7 is formed in a rectangular plate shape. The inner surface 7a and the outer surface 7b of the side plate 7 form planes perpendicular to the axis of the roller 4 (Figure 3). The inner diameter portion of the side plate 7 is restricted so as not to rotate by the small rib portion 2c (Figure 1) and the large rib portion 2b (Figure 1) of the inner ring 2. The inner surface 7a of the side plate 7 is the surface where the pair of side plates 7, 7 face each other in the axial direction.

[0027] A pair of pillars 8, 8 is installed across the outer diameter portions of the side plates 7, 7 and extends axially along the surface of the roller. The pair of pillars 8, 8 is arranged at a predetermined interval in the circumferential direction. The pair of side plates 7, 7 and the pair of pillars 8, 8 form a single pocket Pt. As shown in Figure 3, each pillar portion 8 is located on the outer diameter side of the pitch circle diameter PCD (Figure 2) of the rollers 4. The pitch circle diameter PCD in Figure 2 is calculated by (inner diameter dimension of inner ring 2 + outer diameter dimension of outer ring 3) / 2. Furthermore, when multiple cage segments 6 are arranged in the circumferential direction, the circumferential side surfaces of circumferentially adjacent side plates 7, 7 are adjacent to each other.

[0028] <Regarding the engaging and engaged parts> As shown in Figures 4 and 5, the inner surface 7a of each side plate 7 is provided with engaging portions 9 that protrude axially inward and face each other in the axial direction. Engaged portions 10 that rotatably engage with the engaging portions 9 are provided in the center of both axial end surfaces of the rollers 4. The engaging portions 9 of the side plates 7 are detachable from the engaged portions 10 of the rollers 4. As shown in Figures 6 and 7, the engaging portions 9 are spherical protrusions that protrude axially inward from the inner surface 7a of each side plate 7. The engaged portions 10 of the rollers 4 are concave spherical recesses that engage with the spherical protrusions.

[0029] The inner diameter surface 7c of each side plate 7 faces the radially opposing small flange portion 2c and large flange portion 2b (Fig. 1) via a predetermined radial gap δ1. The radial gap δ2 between the engaging portion 9 and the engaged portion 10 of the side plate 7 is smaller than the radial gap δ1 between the inner diameter surface 7c of the side plate 7 and the large flange portion 2b (Fig. 1) and small flange portion 2c. When the engaged portion 10 of each roller 4 is engaged with the engaging portion 9 of the side plate 7, a predetermined axial gap δ3 is set between one axial end face of the roller 4 and the inner surface 7a of the side plate 7 that faces this axial end face. Furthermore, when the engaged portion 10 of each roller 4 is engaged with the engaging portion 9 of the side plate 7, a portion of the rolling surface 4a of each roller 4 protrudes outward from the outer diameter surface 8a of the column portion 8, and a portion of the rolling surface 4a of each roller 4 protrudes inward from the inner diameter surface 7c of each side plate 7.

[0030] <Action and effect> According to the tapered roller bearing 1 of Figure 1 explained above, each column portion 8 of the cage segment 6 of Figure 4 is provided on the outer diameter side of the pitch circle diameter PCD (Figure 2) of the rollers 4. Therefore, compared to conventional segment cages, it is possible to relax the restrictions on the roller diameter and number of rollers imposed by the circumferential thickness of the column portions 8. This makes it possible to increase the load capacity of the roller bearing compared to roller bearings equipped with conventional segment cages.

[0031] 4 and 5, engaged portions 10 are provided at the center of both axial end faces of rollers 4, which rotatably engage with engaging portions 9 on the inner surfaces 7a of each side plate 7. This makes it possible to restrict movement of the cage segments 6 toward the outer diameter side. As a result, even if the cage 5 in FIG. 1 is not outer ring guided and the column portions 8 of the cage 5 are positioned on the outer diameter side so as not to overlap the pitch circle diameter PCD (FIG. 2) of the rollers 4, it is possible to prevent the cage segments 6 from falling toward the outer ring side. This makes it possible to prevent the loss of the function of guiding the rollers 4.

[0032] Furthermore, the cage segment 6 has a pair of side plates 7, 7 that face each other in the axial direction. Therefore, as shown in Figure 2, the inner diameter portion of the side plate 7 is restricted by the inner ring 2. This can restrict the cage segment 6 from rotating around the roller axis. Therefore, when assembling the cage segment 6 and roller 4 into the bearing, the cage segment 6 can be maintained in a predetermined direction without requiring special care. This reduces the number of steps in the assembly work.

[0033] As shown in Figures 6 and 7, the engaging portions 9 are spherical protrusions that protrude axially inward from the inner surface 7a of each side plate 7, and the engaged portions 10 of the rollers 4 are concave spherical recesses that engage with the spherical protrusions. In this way, by engaging the concave spherical recesses with the spherical protrusions, it is possible to reduce wear due to sliding movement between them. When the engaged portions 10 of the rollers 4 are recesses, recesses can easily be added to both axial end faces of a standard roller.

[0034] The inner diameter surface 7c of each side plate 7 faces the radially opposing small rib portion 2c and large rib portion 2b (Fig. 1) via a specified radial gap δ1. This configuration makes it possible to avoid contact between the inner diameter surface 7c of the side plate 7 and the small rib portion 2c and large rib portion 2b (Fig. 1) of the inner ring 2 during use of the roller bearing. This prevents wear, torque, and heat generation on the inner diameter surface 7c of the side plate 7 and the small rib portion 2c and large rib portion 2b (Fig. 1) of the inner ring 2, thereby improving the performance and reliability of the roller bearing. In particular, the radial gap δ2 between the engaging portion 9 and the engaged portion 10 of the side plate 7 is smaller than the radial gap δ1 between the inner diameter surface 7c of the side plate 7 and the large rib portion 2b (Fig. 1) and small rib portion 2c. In this case, the relative radial movement of the cage 5 (Fig. 1) with respect to the rollers 4 is restricted, more reliably preventing contact between the inner diameter surface 7c of the side plate 7 and the flange of the inner ring 2. The cage segments 6 are made of a resin material, which allows for lower manufacturing costs than machining a metal cage.

[0035] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments as long as there is no particular problem with the combination.

[0036] [Second embodiment: Figure 8, multiple pockets] As shown in Figure 8, the cage segment 6 may be a cage segment in which multiple (two in this example) pockets Pt for holding rollers 4 are arranged in the circumferential direction. In this case, three pillar portions 8 are arranged at a predetermined interval in the circumferential direction. Two pockets Pt are formed by a pair of side plates 7 and three pillar portions 8. The number of pockets may be three or more. A roller bearing equipped with such a multiple-pocket cage segment 6 also achieves the same effects as the first embodiment.

[0037] [Third embodiment: FIG. 9A, modified examples of the engaging portion and the engaged portion] 9A, the engaging portion 9 of the side plate 7 is conical in shape with a diameter that decreases axially inward. The engaged portion 10 of the roller 4 may be a conical hole that rotatably engages with the conical engaging portion 9. A roller bearing equipped with such cage segments 6 and rollers 4 also achieves substantially the same effects as the first embodiment.

[0038] [Fourth embodiment: FIG. 9B, modified examples of the engaging portion and the engaged portion] As shown in Figure 9B, the inner surface 7a of each side plate 7 is provided with engaging portions 9 that are recessed axially outward and face each other in the axial direction. The engaging portions 9 are spherical recesses that recess axially outward from the inner surface 7a of each side plate 7. The engaged portions 10 of the rollers 4 are spherical protrusions that engage with the spherical recesses. A roller bearing equipped with such cage segments 6 and rollers 4 also achieves substantially the same effects as the first embodiment.

[0039] <Application example to wind power generation equipment> FIG. 10 shows an example of a wind turbine generator using a tapered roller bearing 1 according to any of the embodiments. In this wind turbine generator, a main shaft 53 of a propeller-shaped wind turbine 52 is rotatably supported by a tapered roller bearing 1, which serves as a main shaft bearing, on a nacelle 51 that is installed so as to be able to freely swing horizontally at the top end of a support 50. The main shaft bearing is a large bearing with an outer diameter of 1 m or more. The main shaft 53 is connected to a generator 54 via a gearbox 55. A tapered roller bearing 1 according to the embodiment is used as the main shaft bearing in this wind turbine generator. In this case, the tapered roller bearing 1, which can increase the load capacity and reduce the number of assembly steps, can be applied to large bearings used in wind power generation equipment.

[0040] The engaging portion 9 and the engaged portion 10 in FIGS. 7, 9A, and 9B are not limited to the shapes in the embodiment, and various shapes can be applied. The roller bearing according to the embodiment is not limited to a tapered roller bearing, but may also be a cylindrical roller bearing or a needle roller bearing. The retainer segments may be formed by a 3D printer. The retainer segments may be made of metal.

[0041] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0042] REFERENCE SIGNS LIST 1... tapered roller bearing, 2... inner ring, 2a... raceway surface, 2b... large rib portion (rib portion), 2c... small rib portion (rib portion), 3... outer ring, 4... rollers, 5... cage, 6... cage segment, 7... side plate, 8... column portion, 9... engaging portion, 10... engaged portion

Claims

1. A roller bearing comprising an inner ring, an outer ring, a plurality of rollers interposed between the inner ring and the outer ring, and a cage having pockets formed therein for holding the rollers, the cage being made up of a plurality of cage segments arranged in the circumferential direction, The cage segment has a pair of side plates facing each other in the axial direction and a plurality of pillar portions extending parallel to the axial direction and spanning the pair of side plates, the pair of side plates and the plurality of pillar portions defining the pockets, Each of the pillar portions is provided on the outer diameter side of the pitch circle diameter of the roller, An inner surface of each of the side plates is provided with engaging portions that protrude inward in the axial direction or are recessed outward in the axial direction and are opposed to each other in the axial direction, A roller bearing in which engaged portions that rotatably engage with the engaging portions are provided at the centers of both axial end surfaces of the rollers.

2. 2. A roller bearing according to claim 1, wherein the engaging portions are spherical protrusions protruding axially inward from the inner surfaces of the side plates, and the engaged portions of the rollers are concave spherical recesses that engage with the spherical protrusions.

3. 3. A roller bearing according to claim 1 or claim 2, wherein the inner ring has a raceway surface on which the rollers roll and ribs provided on both axial sides of the raceway surface, and each of the side plates has an inner diameter surface facing the radially opposing ribs with a predetermined radial gap δ1 between them.

4. 4. The roller bearing according to claim 3, wherein a radial gap δ2 between the engaging portion of the side plate and the engaged portion is smaller than a radial gap δ1 between the inner diameter surface of the side plate and the flange portion.

5. 3. A roller bearing according to claim 1, wherein the cage segments are made of a resin material.

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