Rolling bearing

Abstract

This rolling bearing comprises an outer member (1) and an inner member (2), a plurality of rolling elements (3) disposed along the circumferential direction in an annular space between an inner diameter surface of the outer member (1) and an outer diameter surface of the inner member (2), a locking portion (11) in the circumferential direction provided on one of the outer member (1) and the inner member (2) and a sliding contact portion (12) in the circumferential direction provided on another outer member (1) and another inner member (2), and a retaining ring (20) that abuts the locking portion (11) and the sliding contact portion (12) and that makes electrical connections between the outer member (1) and the inner member (2), wherein the retaining ring (20) is electrically conductive and elastically deformable, and is a rolling bearing that contacts the sliding contact portion (12) with an interference a in the axial direction.

Description

Rolling bearings

[0001] The present invention relates to a rolling bearing having a function of preventing electrolytic corrosion.

[0002] Electrically insulating, electrolytic corrosion-resistant rolling bearings have been proposed for use in the vicinity of electrically charged structures, such as the motors of electric vehicles and the main motors of railway vehicles. Electrolytic corrosion-resistant rolling bearings prevent electrolytic corrosion from occurring in metal components such as raceways when current flows from raceways that are electrically connected to the outside to the rolling elements.

[0003] Examples of electrolytic corrosion-resistant rolling bearings include those described in Patent Documents 1 and 2. In these rolling bearings, the internal space of the bearing, where the rolling elements are installed, is filled with conductive grease, and electrical conduction is achieved between the inner and outer raceways through the conductive grease. Patent Document 3 describes a rolling bearing in which a thin conductive wire is embedded in a seal member fixed to one raceway, with the tip of the wire protruding from the seal member and sliding against the opposing raceway. Patent Document 4 also describes a rolling bearing that includes a current-carrying member that provides electrical conduction between the inner and outer raceways, located axially outward of the seal member, and that slides against the opposing raceway via a brush.

[0004] In addition, the rolling bearing described in Patent Document 5 has a C-shaped metal wire fitted onto the circumferential surface of one of the inner or outer raceways, and both ends of the wire are bent and slide against the circumferential surface of the other, providing electrical continuity between the inner and outer raceways.Furthermore, the rolling bearing described in Patent Document 6 has a spiral spring disposed between the inner and outer raceways, and the spring has an outer peripheral portion that elastically abuts against the inner circumferential surface of the outer ring, and an inner peripheral portion that elastically abuts against the outer circumferential surface of the inner ring, providing electrical continuity between the inner and outer raceways.

[0005] JP 2015-102200 A JP 2010-261522 A JP 2008-286331 A JP 2019-86152 A JP 11-218143 A JP 2-110717 A

[0006] The use of conductive grease in Patent Documents 1 and 2 has the problem of shortening the life of the grease, while Patent Documents 3 and 4 have the problem of complicating the bearing structure and increasing costs by embedding conductive thin wires in the sealing member or arranging a current-carrying member equipped with a brush.

[0007] The wire rods in Patent Documents 5 and 6, which use a C-shaped or spiral-shaped wire rod, are relatively inexpensive. However, because the wire rod and the raceway are in radial contact, both the inner diameter portion and the outer diameter portion of the wire rod must be deformed to attach it to the bearing, which creates problems with workability. Furthermore, because the ends of the wire rod are open (the shape is not closed in a ring), there is a problem with workability during assembly, such as the end of the wire rod becoming entangled with other components, such as a retaining ring.

[0008] Therefore, an object of the present invention is to improve the workability during assembly while suppressing an increase in cost.

[0009] In order to solve the above problems, the present invention provides a rolling bearing comprising an outer member and an inner member, a plurality of rolling elements arranged circumferentially in an annular space between the inner diameter surface of the outer member and the outer diameter surface of the inner member, a circumferential locking portion provided on one of the outer member and the inner member and a circumferential sliding portion provided on the other, and a retaining ring abutting against the locking portion and the sliding portion to electrically connect the outer member and the inner member, the retaining ring being conductive and elastically deformable, and being in axial contact with the sliding portion with an interference (structure 1).

[0010] In configuration 1, one of the outer member and the inner member is a fixed-side raceway ring, and the other is a rotating-side raceway ring, and a configuration can be adopted in which the retaining ring is in contact with only the rotating-side raceway ring with an interference in the axial direction (configuration 2).

[0011] In an embodiment having configuration 1, or an embodiment having configurations 1 and 2, the retaining ring can have a configuration in which first portions that are engaged with the engaging portion and second portions that slide against the sliding portion are arranged alternately along the circumferential direction (configuration 3).

[0012] In an embodiment having configuration 1, an embodiment having configuration 1 plus configuration 2 or configuration 3, or an embodiment having configuration 1 plus configurations 2 and 3, one of the outer member and the inner member is a fixed side raceway ring, and the other is a rotating side raceway ring, and the retaining ring can rotate relative to the rotating side raceway ring around the axis (configuration 4).

[0013] In the embodiment including the configuration 1 or the embodiment in which one or more elements selected from the configurations 2, 3, and 4 are added to the configuration 1, the retaining ring can be an endless ring-shaped member (Configuration 5). Here, endless means a member having a closed shape without any gaps, and means a member that does not create an opening even when a part of it is elastically deformed.

[0014] In the embodiment including the configuration 1 or the embodiment in which one or more elements selected from the configurations 2, 3, 4, and 5 are added to the configuration 1, the retaining ring can have a surface layer made of a conductive material on its surface (configuration 6).

[0015] According to this invention, it is possible to improve the workability during assembly while suppressing an increase in costs.

[0016] 4 is a cross-sectional view showing a state after deformation for assembling a retaining ring; sectional view showing a state before assembling the retaining ring; sectional view of a rolling bearing according to another embodiment of the present invention; sectional view of a rolling bearing according to yet another embodiment of the present invention; sectional view of a rolling bearing according to yet another embodiment of the present invention;

[0017] An embodiment of the present invention will now be described with reference to the drawings. This embodiment relates to an electrolytic corrosion-resistant rolling bearing that is applicable to various industrial machines and various transportation machines such as electric vehicles and railway vehicles. The bearing is particularly effective in applications where the bearing rings are electrically connected to the outside and current can flow through the rolling elements.

[0018] As shown in Figure 1, the electrolytic corrosion resistant rolling bearing 10 (hereinafter simply referred to as the bearing 10) comprises an annular outer member 1 and an annular inner member 2 arranged with their axes aligned, and a plurality of rolling elements 3 arranged circumferentially in the annular space between the inner diameter surface 1b of the outer member 1 and the outer diameter surface 2b of the inner member 2. The rolling elements 3 are arranged between the raceway surface 1a of the outer member 1 and the raceway surface 2a of the inner member 2, and are held at regular intervals circumferentially by an annular cage 4.

[0019] Hereinafter, the direction along the axial center of the outer member 1 and the inner member 2 will be referred to as the "axial direction." The axial direction corresponds to the left-right direction in Figures 1 and 2. In addition, in Figures 1 and 2, the left direction will be referred to as the "axial one side" or simply "one side," and the right direction will be referred to as the "axial other side" or simply "other side." Furthermore, the direction perpendicular to the axial center will be referred to as the "radial direction." The radial direction corresponds to the up-down direction in Figures 1 and 2. In addition, the circumferential direction around the axial center will be referred to as the "axial direction" or "circumferential direction."

[0020] The outer member 1 has its outer diameter surface 1c fixed to the inner diameter portion of a housing (not shown) having an annular or other shape, and supports the rotating shaft so as to be rotatable about its axis. Note that instead of this housing, the outer member 1 may be fixed to the inner diameter portion of a gear or the like. Also, the inner diameter portion of the housing or gear may be integral with these components to form the outer member 1. Hereinafter, in this embodiment, the outer member 1 will be referred to as an outer ring 1.

[0021] The inner diameter surface 2c of the inner member 2 is fixed to the outer diameter portion of a rotating shaft (not shown) and rotates about the axis integrally with the rotating shaft. The rotating shaft is, for example, a rotating part of a driving force transmission path in various machines and devices, specifically, a driving shaft of a motor in an electric vehicle, or a rotating part such as a transmission, drive shaft, or propeller shaft in various automobiles. Hereinafter, in this embodiment, the inner member 2 will be referred to as an inner ring 2.

[0022] This embodiment is a deep groove ball bearing that uses steel balls as the rolling elements 3. Furthermore, raceway surfaces 1a, 2a formed on the inner diameter surface of the outer ring 1 and the outer diameter surface of the inner ring 2 have arc-shaped cross sections corresponding to the balls, as shown in the longitudinal cross sections of Figures 1 and 2. The cage 4 is made of metal, but may also be made of resin. The outer ring 1 and inner ring 2 are made of metal and are electrically connected to the outside through the housing and shaft that contact them. Therefore, electric current may flow through the outer ring 1 and inner ring 2 depending on the operating state of the device.

[0023] Note that multiple seal members (not shown) may be attached between the outer ring 1 and the inner ring 2. The seal members may be made of rubber, resin, metal, or a combination thereof, depending on the specifications of the bearing.

[0024] A retaining ring 20 is disposed between the outer ring 1 and the inner ring 2. The retaining ring 20 is a ring-shaped member made of conductive and elastically deformable wire. In this embodiment, the outer ring 1 is the fixed-side raceway ring, and the inner ring 2 is the rotating-side raceway ring. Therefore, the retaining ring 20 is fixed to the outer ring 1, which is the fixed-side raceway ring. However, the retaining ring 20 may be fixed so as not to rotate relative to the rotating-side raceway ring about the axis, or may be fixed so as to be rotatable relative to the rotating-side raceway ring about the axis.

[0025] The outer ring 1 is provided with a locking portion 11 along the circumferential direction. The locking portion 11 is composed of a groove provided around the entire circumference on the inner diameter surface of the outer ring 1. The inner ring 2 is provided with a sliding portion 12 along the circumferential direction. The sliding portion 12 is composed of a cylindrical surface 12a and an inclined surface 12b along the entire circumference provided on the outer diameter surface of the inner ring 2. However, the sliding portion 12 may be configured in such a way that the cylindrical surface 12a is omitted.

[0026] The first portion 21 set on the retaining ring 20 abuts (is engaged with) the locking portion 11 of the outer ring 1, and the second portion 22 set on the retaining ring 20 abuts (is in sliding contact with) the sliding contact portion 12 of the inner ring 2, so the retaining ring 20 electrically connects the outer ring 1 and the inner ring 2. As a result, the outer ring 1 and the inner ring 2 are electrically connected through the highly conductive retaining ring 20, which prevents electricity from passing through the rolling elements 3. This makes it possible to prevent electrolytic corrosion from occurring in metal parts such as raceways. Here, it is desirable that the electrical resistance of the retaining ring 20 between the outer ring 1 and the inner ring 2 be set smaller than the electrical resistance of the rolling elements 3.

[0027] In this embodiment, the locking portion 11 of the outer ring 1, which is the fixed raceway ring, is formed as a groove, so that the retaining ring 20 can be easily fitted and fixed to the outer ring 1. Here, as shown in Figure 5, a cylindrical surface 13 with a smaller diameter than the bottom of the groove of the locking portion 11 is provided on the axially outer side of the locking portion 11, so that the retaining ring 20 is smoothly guided toward the groove.

[0028] Furthermore, since the inner ring 2, which is the raceway ring on the rotating side, is provided with the inclined surface 12b as the sliding contact portion 12, it is possible to stabilize the contact state between the snap ring 20 and the outer ring 1, and between the snap ring 20 and the inner ring 2, regardless of dimensional errors (tolerances) of the outer ring 1 and the inner ring 2 and the snap ring 20. Furthermore, it is possible to ensure a relatively wider contact area for the inner ring 2 than when the snap ring 20 contacts a cylindrical surface.

[0029] Here, the retaining ring 20 contacts the inner ring 2, which is the rotating raceway, with an interference a in the axial direction. While FIG. 3 depicts the inclined surface 12b of the inner ring 2 and the retaining ring 20 as overlapping by the axial dimension indicated by the symbol a, the actual components do not overlap as shown. Instead, the retaining ring 20 abutting against the inclined surface 12b presses against the inclined surface 12b with an interference a, which is the axial dimension indicated by the symbol a. This pressure further stabilizes the contact state between the retaining ring 20 and the inner ring 2. Furthermore, by making the contact between the rotating raceway and the retaining ring 20 axial rather than radial, it is not necessary to deform both the inner diameter and outer diameter of the wire during assembly, as in the conventional method, making the assembly process easier. Furthermore, it also makes it easier to manage the interference at the contact points.

[0030] In addition, in this embodiment, the retaining ring 20 is an endless ring-shaped member, which has the advantage that it is easy to insert the retaining ring 20 while elastically deforming it. Also, since the end of the wire is not open (it has a closed annular shape), the end of the wire will not become entangled with other components.

[0031] It is sufficient that the retaining ring 20 is in contact with at least one of the locking portion 11 and the sliding contact portion 12 with an interference a in the axial direction. The interference a in the axial direction may be set for both the locking portion 11 and the sliding contact portion 12, but when this is set for only one of them, it is advantageous to set the interference a in the axial direction for the rotating side raceway (sliding contact portion 12) as in this embodiment.

[0032] As shown in FIG. 1, the retaining ring 20 has first portions 21 that are locked to the locking portions 11 and second portions 22 that slide against the sliding contact portions 12, which are arranged alternately along the circumferential direction, so that the distance of the current path between the outer ring 1 and the inner ring 2 can be made as short as possible.

[0033] Figure 7 shows the shape of the retaining ring 20 before it is mounted in the bearing 10. Figure 6 shows the state in which an external force is applied to the retaining ring 20 to elastically deform it in preparation for mounting it in the bearing 10. As shown in Figure 6, the entire retaining ring 20 is deformed to a diameter smaller than that of the locking portion 11, and a portion of it is brought into contact with (fitted into) the locking portion 11. If the external force is then released, the intermediate portion between adjacent first portions 21 will come into contact with the sliding contact portion 12, as shown in Figure 1. Here, the portion that contacts the sliding contact portion 12 corresponds to the second portion 22.

[0034] 8 to 10 show other embodiments of the present invention.

[0035] 8 shows a retaining ring 20 having three first portions 21 that are locked to the locking portion 11 and three second portions 22 that come into sliding contact with the sliding contact portion 12. Because there are three first portions 21 with a large curvature (small curve radius) and three second portions 22 with a small curvature (large curve radius or straight), the retaining ring 20 has a triangular shape overall.

[0036] In this way, the number of first portions 21 and second portions 22 can be changed as appropriate depending on the specifications of the bearing 10. Here, similar to the above-described embodiment, the first portions 21 that are locked to the locking portions 11 and the second portions 22 that slide against the sliding contact portions 12 are provided alternately along the circumferential direction. Note that it is also possible to consider an embodiment in which the first portions 21 and the second portions 22 are not alternately arranged along the circumferential direction, but rather the first portions 21 and the second portions 21 are adjacent to each other along the circumferential direction, or there is an intervening portion where the second portions 22 and the second portions 22 are adjacent to each other along the circumferential direction.

[0037] 9 shows a retaining ring 20 with an open C-shape at the end. Because the end of the wire is open (it is not closed in a ring shape), the end of the wire is bent into an arc shape to prevent it from interfering with other components. This bent portion of the end serves as a first portion 21 (end arc portion 23) that engages with the engaging portion 11 of the outer ring 1. In addition to the end arc portion 23, two first portions 21 are provided in the middle of the wire in the longitudinal direction, resulting in a triangular retaining ring 20 that is similar overall to the embodiment shown in FIG. 8.

[0038] In this way, the retaining ring 20 is not limited to an endless ring-shaped member, and a retaining ring 20 with open ends (not closed in an annular shape) may be used.

[0039] 10 shows a retaining ring 20 having six first portions 21 and six second portions 22. Six first portions 21 protruding toward the outer diameter side and six second portions 22 protruding toward the inner diameter side are provided, forming a star-shaped retaining ring 20 as a whole. The retaining ring 20 is an endless ring-shaped member, but it may also be a retaining ring 20 with open ends (not closed annularly) as in FIG. 9.

[0040] In any of the embodiments, the retaining ring 20 may be made entirely of a conductive material (for example, a metal such as iron), or if a non-conductive material (for example, rubber or resin) is used, the retaining ring 20 may be configured to have a surface layer made of a conductive material (for example, a metal film, a metal coating, etc.) on its surface.

[0041] In the above embodiment, the outer ring 1 is the fixed-side raceway ring and the inner ring 2 is the rotating-side raceway ring. However, this may be reversed, with the outer ring 1 being the rotating-side raceway ring and the inner ring 2 being the fixed-side raceway ring. In this case, it is desirable that the retaining ring 20 be engaged with the inner ring 2, which is the fixed-side raceway ring. In this case, it is desirable that the shapes of the engaging portion and the sliding contact portion are also reversed, with the sliding contact portion being provided on the outer ring 1 and the retaining portion being provided on the inner ring 2. It is desirable that the sliding contact portion provided on the outer ring 1 be configured with a cylindrical surface and an inclined surface (or only an inclined surface) formed along the circumferential direction, and the retaining portion provided on the inner ring 2 be configured with a circumferential groove. In addition, the retaining ring 20 has a first portion 21 that engages with the engaging portion on the inner ring 2 side and a second portion 22 that slides against the sliding contact portion 12 on the outer ring 1 side.

[0042] In any of the embodiments, the material of the retaining ring 20 is not limited to wire, and the retaining ring 20 may be made of a material other than wire, such as a plate material.

[0043] In the above embodiment, steel balls are used as the rolling elements 3, but other metallic materials or other materials may be used for the rolling elements 3. Also, in the above embodiment, a deep groove ball bearing is used as the bearing 10, but the type of bearing 10 is not limited to this embodiment. For example, it may be another ball bearing such as an angular contact ball bearing, a roller bearing using cylindrical rollers or tapered rollers, or any other rolling bearing.

[0044] REFERENCE SIGNS LIST 1 Outer member (outer ring) 1a Outer raceway surface 2 Inner member (inner ring) 2a Inner raceway surface 3 Rolling element 4 Cage 10 Rolling bearing (bearing) 11 Locking portion 12 Sliding contact portion 12a Cylindrical surface 12b Inclined surface 20 Retaining ring 21 First portion 22 Second portion

Claims

1. A rolling bearing comprising: an outer member (1) and an inner member (2); a plurality of rolling elements (3) arranged circumferentially in an annular space between the inner diameter surface of the outer member (1) and the outer diameter surface of the inner member (2); a circumferential locking portion (11) provided on one of the outer member (1) and the inner member (2) and a circumferential sliding portion (12) provided on the other of the outer member (1) and the inner member (2); and a retaining ring (20) abutting against the locking portion (11) and the sliding portion (12) to electrically connect the outer member (1) and the inner member (2), wherein the retaining ring (20) is conductive and elastically deformable, and is in contact with the sliding portion (12) with an interference (a) in the axial direction.

2. A rolling bearing as claimed in claim 1, wherein one of the outer member (1) and the inner member (2) is a fixed side raceway and the other is a rotating side raceway, and the retaining ring (20) is in contact with only the rotating side raceway with an interference (a) in the axial direction.

3. A rolling bearing as described in claim 1 or 2, wherein the retaining ring (20) has a first portion (21) that is engaged with the engaging portion (11) and a second portion (22) that is in sliding contact with the sliding contact portion (12) that are arranged alternately along the circumferential direction.

4. A rolling bearing as described in any one of claims 1 to 3, wherein one of the outer member (1) and the inner member (2) is a fixed side raceway ring and the other is a rotating side raceway ring, and the retaining ring (20) is rotatable relative to the rotating side raceway ring about its axis.

5. A rolling bearing according to any one of claims 1 to 4, wherein the retaining ring (20) is an endless ring-shaped member.

6. A rolling bearing according to any one of claims 1 to 5, wherein the retaining ring (20) has a surface layer made of a conductive material on its surface.

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