Rolling bearing

Abstract

To improve workability during assembly while suppressing cost increase.SOLUTION: A rolling bearing comprises: an outward member 1 and an inward member 2; a plurality of rolling elements 3 arranged circumferentially in an annular space between an inner diameter surface of the outward member 1 and an outer diameter surface of the inward member 2; a circumferential locking part 11 provided on one of the outward member 1 and the inward member 2; a circumferential slide contact part 12 provided on the other member; and a snap ring 20 that is in contact with the locking part 11 and the slide contact part 12 to electrically connect the outward member 1 and the inward member 2. The snap ring 20 is conductive and elastically deformable, and is in axial contact with the slide contact part 12 with an interference a.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

[0003] Examples of electrolytic corrosion-resistant rolling bearings include the rolling bearings described in Patent Documents 1 and 2. In these rolling bearings, conductive grease is filled into the bearing internal space in which the rolling elements are installed, and electrical conduction is established between the inner and outer raceways through the conductive grease. In addition, the rolling bearing described in Patent Document 3 has a conductive thin wire embedded in a seal member fixed to one raceway, and the tip of the thin wire protrudes from the seal member and is in sliding contact with the opposite raceway. Furthermore, the rolling bearing described in Patent Document 4 has a current-carrying member that conducts electrical conduction between the inner and outer raceways outside the seal member in the axial direction of the bearing, and the current-carrying member is in sliding contact with the opposite 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 and outer raceways, and both ends of the wire are bent and slide against the circumferential surface of the other raceway, 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 an outer peripheral portion of the spring 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. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-102200 A [Patent Document 2] JP 2010-261522 A [Patent Document 3] JP 2008-286331 A [Patent Document 4] JP 2019-86152 A [Patent Document 5] Japanese Patent Application Publication No. 11-218143 [Patent Document 6] Japanese Patent Application Publication No. 2-110717 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Documents 1 and 2 use conductive grease, which has the problem of shortening the grease life, while Patent Documents 3 and 4 have the problem of making the bearing structure complicated and expensive by embedding conductive wires in the seal member or arranging a current-carrying member equipped with a brush.

[0007] In Patent Documents 5 and 6, a C-shaped or spiral wire is used, which is relatively inexpensive. However, because the wire and the raceway are in radial contact, both the inner and outer diameter parts of the wire must be deformed to attach it to the bearing, which creates problems with workability. In addition, because the ends of the wire are open (the shape is not closed in a ring), the ends of the wire can get tangled with other components, such as a retaining ring, which creates problems with workability during assembly.

[0008] Therefore, an object of the present invention is to improve the ease of assembly while suppressing an increase in cost. [Means for solving the problem]

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

[0012] In a configuration having configuration 1, a configuration having configuration 1 plus configuration 2 or configuration 3, or a configuration having configuration 1 plus configurations 2 and 3, a configuration can be adopted in which 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 is rotatable relative to the rotating side raceway ring about an axis (configuration 4).

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

[0014] In a configuration having configuration 1 or a configuration in which a single or multiple elements selected from configuration 2, configuration 3, configuration 4, and configuration 5 are added to configuration 1, the retaining ring can have a surface layer made of a conductive material on its surface (configuration 6). Effect of the Invention

[0015] According to the present invention, the workability during assembly can be improved while suppressing an increase in costs. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a rolling bearing according to an embodiment of the present invention; [Diagram 2] Cross-sectional view of Fig. 1 along line II-II [Diagram 3] Enlarged view of the main part of Figure 2 [Figure 4] IV-IV cross section of Figure 2 [Diagram 5] Enlarged view of the main part of Figure 4 [Figure 6] Cross-sectional view showing the state in which the retaining ring is deformed for installation [Figure 7] Cross-sectional view showing the state before the retaining ring is installed [Figure 8] 1 is a cross-sectional view of a rolling bearing according to another embodiment of the present invention; [Figure 9] FIG. 3 is a cross-sectional view of a rolling bearing according to still another embodiment of the present invention. [Figure 10] FIG. 3 is a cross-sectional view of a rolling bearing according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment is an electrolytic corrosion resistant rolling bearing that is applied to various industrial machines and various transport machines such as electric vehicles and railway cars. It is particularly effective in applications where the raceway is electrically connected to the outside and current can flow through the rolling elements.

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

[0019] Hereinafter, the direction along the axis 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 Figs. 1 and 2. In addition, in Figs. 1 and 2, the left direction will be referred to as the "axial one side" or simply as the "one side", and the right direction will be referred to as the "axial other side" or simply as the "other side". Furthermore, the direction perpendicular to the axis will be referred to as the "radial direction". The radial direction corresponds to the up-down direction in Figs. 1 and 2. Furthermore, the circumferential direction around the axis 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 part of a housing (not shown) having a ring-like shape or the like, 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 part of a gear or the like. Also, the inner diameter part of the housing or gear may be integral with these members 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 member 2 has an inner diameter surface 2c fixed to an outer diameter portion of a rotating shaft (not shown) and rotates around the axis integrally with the rotating shaft. The rotating shaft is, for example, a rotating portion 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 portion such as a transmission, drive shaft, or propeller shaft in various automobiles. Hereinafter, in this embodiment, the inner member 2 is 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 an arc-shaped cross section corresponding to the balls, as shown in the longitudinal sections of Figures 1 and 2. The cage 4 is made of metal, but may be made of resin. The outer ring 1 and the inner ring 2 are made of metal, and are electrically connected to the outside through the housing and shaft that contact them. For this reason, the outer ring 1 and the inner ring 2 may be in a state where a current flows 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 of these materials 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 a wire material that is conductive and elastically deformable. In this embodiment, the outer ring 1 is a fixed raceway ring, and the inner ring 2 is a rotating raceway ring. For this reason, the retaining ring 20 is fixed to the outer ring 1, which is the fixed raceway ring. However, the retaining ring 20 may be fixed so as not to rotate relative to the rotating raceway ring about the axis, or may be fixed so as to be rotatable relative to the rotating 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 on the inner diameter surface of the outer ring 1 over the entire circumference. 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 over 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 manner 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 portion 12 of the inner ring 2, so that 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 retaining ring 20, which has high electrical conductivity, so that the flow of electricity through the rolling elements 3 can be suppressed. 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 is set to be 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 raceway ring on the fixed side, 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 Fig. 5, a cylindrical surface 13 having 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 retaining ring 20 and the outer ring 1, and between the retaining ring 20 and the inner ring 2, regardless of the dimensional errors (tolerances) of the outer ring 1 and the inner ring 2 and the retaining ring 20. Furthermore, it is possible to ensure a relatively wider contact area of ​​the inner ring 2 than when the retaining ring 20 contacts a cylindrical surface.

[0029] Here, the retaining ring 20 contacts the inner ring 2, which is the raceway on the rotating side, with an interference a in the axial direction. In FIG. 3, the inclined surface 12b of the inner ring 2 and the retaining ring 20 are shown overlapping by the axial dimension indicated by the symbol a, but in actuality, they do not overlap as shown, and the retaining ring 20 abutting against the inclined surface 12b presses the inclined surface 12b with the axial dimension indicated by the symbol a as interference a. This pressure further stabilizes the contact state between the retaining ring 20 and the inner ring 2. In addition, by making the contact between the raceway on the rotating side and the retaining ring 20 in the axial direction instead of the radial direction, it is not necessary to deform both the inner diameter part and the outer diameter part of the wire when assembling the retaining ring, as in the conventional case, and the assembling work is made easier. In addition, the control of the interference of the contact part is also made easier.

[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 is closed in a ring shape), the end of the wire will not get tangled with other members.

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

[0032] As shown in FIG. 1, 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, 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] Fig. 7 shows the shape of the retaining ring 20 before it is mounted in the bearing 10. Fig. 6 shows the state in which the retaining ring 20 is elastically deformed by applying an external force to the retaining ring 20 for mounting in the bearing 10. As shown in Fig. 6, the entire retaining ring 20 is deformed to a diameter smaller than that of the locking portion 11, and a part of it is brought into contact with (fitted into) the locking portion 11. If the external force is then released, the intermediate portion between the adjacent first portions 21 comes into contact with the sliding contact portion 12 as shown in Fig. 1. Here, the portion that contacts the sliding contact portion 12 corresponds to the second portion 22.

[0034] 8 to 10 each show another embodiment 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. Since 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 an overall triangular shape.

[0036] In this way, the number of first portions 21 and second portions 22 can be appropriately changed according to the specifications of the bearing 10. Here, 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, as in the above-described embodiment. 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 first portions 21 are adjacent to each other along the circumferential direction, or a portion in which the second portions 22 and the second portions 22 are adjacent to each other along the circumferential direction is interposed.

[0037] In Fig. 9, the shape of the retaining ring 20 is a C-shape with an open 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 so that it does not interfere with other components. This bent portion of the end is the first portion 21 (end arc-shaped portion 23) that is engaged with the engaging portion 11 of the outer ring 1. In addition to the end arc-shaped portion 23, two first portions 21 are set in the middle of the wire in the length direction, resulting in a triangular retaining ring 20 that is similar overall to the embodiment 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] Fig. 10 shows a retaining ring 20 having six first portions 21 and six second portions 22. The retaining ring 20 has six first portions 21 protruding toward the outer diameter side and six second portions 22 protruding toward the inner diameter side, 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 in a circular shape) as in Fig. 9.

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

[0041] In the above embodiment, the outer ring 1 is the fixed raceway ring, and the inner ring 2 is the rotating raceway ring. However, the outer ring 1 may be the rotating raceway ring, and the inner ring 2 may be the fixed raceway ring. In this case, it is preferable that the retaining ring 20 is engaged with the inner ring 2, which is the fixed raceway ring. At this time, it is preferable that the shapes of the engaging portion and the sliding contact portion are also reversed, and the sliding contact portion is provided on the outer ring 1, and the retaining portion is provided on the inner ring 2. It is preferable that the sliding contact portion provided on the outer ring 1 is composed of 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 is composed of a groove in the circumferential direction. In addition, the retaining ring 20 has a first portion 21 that is engaged with the engaging portion on the inner ring 2 side, and a second portion 22 that is in sliding contact with 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 the rolling elements 3 may be made of other metallic materials or other materials. 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 ball bearing, a roller bearing using cylindrical rollers or tapered rollers, or any other rolling bearing. [Explanation of symbols]

[0044] 1 Outer member (outer ring) 1a Outer raceway surface 2 Inner member (inner ring) 2a Inner raceway surface 3. Rolling elements 4 Cage 10 Rolling bearings (bearings) 11 Locking part 12 Sliding part 12a Cylindrical surface 12b Slope 20 Retaining ring 21 Part 1 22 Second part

Claims

1. An outer member (1) and an inner member (2), a plurality of rolling elements (3) arranged along a 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 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); a retaining ring (20) that contacts the locking portion (11) and the sliding contact portion (12) to electrically connect the outer member (1) and the inner member (2), The retaining ring (20) is conductive and elastically deformable, and is in contact with the sliding contact portion (12) with an interference (a) in the axial direction of the rolling bearing.

2. 2. A rolling bearing according to 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. 2. The rolling bearing according to claim 1, wherein the retaining ring (20) has first portions (21) that are engaged with the engaging portion (11) and second portions (22) that slide against the sliding contact portion (12), which are alternately arranged along the circumferential direction.

4. 2. The rolling bearing according to claim 1, 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 an axis.

5. 2. The rolling bearing according to claim 1, wherein the retaining ring (20) is an endless ring-shaped member.

6. 2. The rolling bearing according to claim 1, wherein the retaining ring (20) has a surface layer made of a conductive material on the surface thereof.

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