Annular conductive member

Abstract

[Problem] To reduce electrical resistance and stabilize contact for current flow in an annular conductive member that is fitted between an outer ring and an inner ring of a rolling bearing into which lubricating oil is supplied. [Solution] An annular conductive member 1 fitted between an outer ring 11 and an inner ring 12 of a rolling bearing, and having a flow path F penetrating the inside and outside of the rolling bearing. The annular conductive member 1 includes an elastic body 4 made of rubber material. A conductive fiber 5 is integrated with a surface layer portion on one surface side of the elastic body, and part of the conductive fiber 5 is exposed from the surface to form a conductive texture portion A. An outer-diameter-side conductive texture portion, which is an outer-diameter-side portion of the conductive texture portion A located at an outer peripheral portion of the elastic body 4, contacts the outer ring 11, and an inner-diameter-side conductive texture portion, which is an inner-diameter-side portion of the conductive texture portion A located at an inner peripheral portion of the elastic body 4, contacts the inner ring 12.

Description

Annular conductive member

[0001] The present invention relates to an annular conductive member that prevents electrolytic corrosion of a rolling bearing.

[0002] For example, current may leak into the rotating shaft in motors and reduction gear units of electric vehicles, as well as inverter-driven motors other than those for electric vehicles. In such cases, the lubricating oil film in the rolling bearing supporting the rotating shaft may be broken, causing current to flow between the outer and inner rings, resulting in arc damage to the rolling surfaces of the rolling elements.

[0003] One structure for preventing electrolytic corrosion in such rolling bearings involves attaching a circular conductive member between the outer and inner rings of a rolling bearing into which lubricating oil is supplied (see, for example, Patent Documents 1 and 2).

[0004] The conductive ring 140, which is an annular conductive member in Patent Document 1, has connecting posts 142 made of a metal material, an inner ring side rubber member 154 made of conductive rubber, and an outer ring side rubber member 152 made of conductive resin. The connecting posts 142 extend radially between the outer ring 110 and the inner ring 120, and between adjacent connecting posts 142 are formed through holes 148 that are flow paths that penetrate the inside and outside of the rolling bearing 100. A conductive lip 150 of the inner ring side rubber member 154 made of conductive rubber slides on the inner ring 120.

[0005] The conductive annular member 15, which is the annular conductive member in Patent Document 2, has a core member 41 made of a metal material and an elastic member 42 made of conductive rubber. The annular member 15 is formed with a hole 51 or a notch 52 that is a flow path that penetrates between the inside and outside of the rolling bearing 10. An elastic lip portion 45 of the elastic member 42 made of conductive rubber slides on the inner ring 12.

[0006] JP 2023-46521 A International Publication No. 2023 / 105618

[0007] A circular conductive member having a flow path that penetrates the inside and outside of a rolling bearing, as in Patent Documents 1 and 2, makes it possible to suppress an increase in stirring resistance when the bearing rotates in a rolling bearing to which lubricating oil is supplied.

[0008] However, the use of conductive rubber in the annular conductive member poses the problem of increased electrical resistance.Conductive rubber is made by dispersing conductive carbon black or metal powder in insulating rubber, and there is a limit to the amount of conductor that can be added in order to maintain the properties of the rubber, resulting in increased electrical resistance.

[0009] Furthermore, because electricity is passed through the conductive rubber lip while it is sliding against the inner ring of the rolling bearing, there is a problem of unstable contact for current flow. That is, because sliding the lip against the inner ring increases the sliding torque, a lubricant such as lubricating oil is used between the sliding surfaces to reduce the sliding torque. As a result, an oil film is formed on the sliding surfaces, creating a fluid lubrication state, reducing the contact area between the sliding surfaces of the inner ring and the lip, and therefore unstable contact for current flow.

[0010] The present invention aims to reduce electrical resistance and stabilize contact for electrical conduction in an annular conductive member mounted between the outer ring and inner ring of a rolling bearing into which lubricating oil is supplied.

[0011] A first aspect of the present invention provides an annular conductive member that is mounted between the outer ring and inner ring of a rolling bearing and has a flow path that penetrates the interior and exterior of the rolling bearing. The annular conductive member has an elastic body made of a rubber material, and a surface layer on one surface of the elastic body has conductive fibers integrated therein and a conductive texture portion formed in which some of the conductive fibers are exposed from the surface. An outer diameter side conductive texture portion, which is the outer diameter side portion of the conductive texture portion located on the outer peripheral portion of the elastic body, contacts the outer ring, and an inner diameter side conductive texture portion, which is the inner diameter side portion of the conductive texture portion located on the inner peripheral portion of the elastic body, contacts the inner ring.

[0012] A second aspect of the present invention provides an annular conductive member that is mounted between the outer ring and inner ring of a rolling bearing and has a flow path that penetrates the interior and exterior of the rolling bearing. The annular conductive member includes a core having an engaging portion that engages with the outer ring, and an elastic body made of a rubber material joined to the core, and a surface layer on one surface of the elastic body is formed with conductive fibers integrated therein, and a conductive texture portion in which some of the conductive fibers are exposed from the surface. An outer diameter side conductive texture portion, which is the outer diameter side portion of the conductive texture portion located on the outer peripheral portion of the elastic body, contacts the core, and an inner diameter side conductive texture portion, which is the inner diameter side portion of the conductive texture portion located on the inner peripheral portion of the elastic body, contacts the inner ring.

[0013] In the annular conductive members according to the first and second aspects, the conductive fibers of the inner diameter side conductive texture portion that are exposed from the surface of the elastic body contact the inner ring of the rolling bearing. Since the conductive fibers of the inner diameter side conductive texture portion conduct electricity while sliding on the inner ring, electrical resistance can be reduced. Since the conductive fibers sliding on the inner ring scrape through the oil film on the sliding surface, an oil film is not formed on the sliding surface, as occurs when a conductive rubber lip slides on the inner ring. Therefore, contact for electrical conduction between the conductive fibers and the inner ring is stable.

[0014] A third aspect of the present invention is an annular conductive member according to the first or second aspect, wherein the inner diameter side conductive texture portion is a circumferentially discontinuous type that is discontinuous in the circumferential direction, or a circumferentially separated type that has radial cuts at predetermined intervals in the circumferential direction.

[0015] In the annular conductive member according to the third aspect, the inner diameter side conductive texture portion is circumferentially discontinuous or circumferentially separated, so the reinforcing effect of the inner diameter side conductive texture portion on the elastic body is suppressed, and therefore the tightening force applied to the inner ring with which the inner diameter side conductive texture portion comes into contact can be reduced, preventing an increase in rotational torque of the rolling bearing.

[0016] A fourth aspect of the present invention is an annular conductive member according to the first aspect, wherein the outer diameter side conductive texture portion is a circumferentially discontinuous type that is discontinuous in the circumferential direction, or a circumferentially separated type that has radial notches at predetermined intervals in the circumferential direction.

[0017] According to the annular conductive member of the fourth aspect, even when the outer diameter side conductive texture portion is molded to be curved within a molding die, the sheet body of conductive fiber having a predetermined shape that becomes the outer diameter side conductive texture portion is easily deformed, thereby increasing the freedom of shape design.

[0018] As described above, the annular conductive member of the present invention is mounted between the outer ring and inner ring of a rolling bearing into which lubricating oil is supplied, and prevents electrolytic corrosion of the rolling bearing. This annular conductive member can reduce electrical resistance and stabilize contact for electrical conduction.

[0019] 1 is an enlarged longitudinal cross-sectional view of a main portion of a rolling bearing including an annular conductive member according to an embodiment of the present invention. FIG. 2 is an enlarged longitudinal cross-sectional view of a main portion showing the periphery of one of the annular conductive members in the rolling bearing of FIG. 1. FIG. 3 is a perspective view showing the inner surface side in the width direction of the annular conductive member according to an embodiment of the present invention, illustrating an example of a conductive texture portion formed by integrating cloth-like conductive fibers into the surface layer portion of an elastic body. FIG. 4 is a partially sectional perspective view showing an enlarged main portion of the annular conductive member of FIG. 3. FIG. 5 is a schematic diagram showing an enlarged cross-section of a conductive texture portion formed by integrating cloth-like conductive fibers into the surface layer portion of an elastic body. FIG. 6 is a partially sectional perspective view similar to FIG. 4, illustrating an example of a conductive texture portion formed by integrating nonwoven cloth-like conductive fibers into the surface layer portion of an elastic body. FIG. 7 is a perspective view showing a first modified example in which no holes are formed in the conductive fibers. FIG. 8 is a perspective view showing a second modified example in which the outer diameter side conductive texture portion and the inner diameter side conductive texture portion are circumferentially discontinuous, being discontinuous in the circumferential direction. FIG. 9 is a perspective view showing a third modified example in which the outer diameter side conductive texture portion and the inner diameter side conductive texture portion are circumferentially separated, having radial cuts made at predetermined circumferential intervals. 10 is an enlarged longitudinal cross-sectional view of a main portion of a fourth modified example in which the inner diameter side conductive texture portion contacts the radial surface of the inner ring. FIG. 11 is an enlarged longitudinal cross-sectional view of a main portion of a fifth modified example in which the core metal engages with the outer ring of the rolling bearing, the outer diameter side conductive texture portion contacts the core metal, and the inner diameter side conductive texture portion contacts the inner ring of the rolling bearing.

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] In this specification, the direction parallel to the direction of the central axis of rotation of the rolling bearing is called the "width direction" (see, for example, arrow B in FIG. 1), and the direction perpendicular to the direction of the central axis of rotation is called the "radial direction" (see, for example, arrow R in FIG. 1). The "circumferential direction" (see, for example, arrow C in FIG. 3) is defined relative to the direction of the central axis of rotation.

[0022] In this specification, the width direction approaching the widthwise center of the rolling bearing (for example, symbol BC in Figure 1) is referred to as the "widthwise inward" (for example, see arrow BI in Figure 1), the width direction moving away from the widthwise center is referred to as the "widthwise outward" (for example, see arrow BO in Figure 1), the radial direction approaching the rotational center axis is referred to as the "radial direction inward" (for example, see arrow RI in Figure 1), and the radial direction moving away from the rotational center axis is referred to as the "radial direction outward" (for example, see arrow RO in Figure 1).

[0023] 1 includes an outer ring 11, an inner ring 12, rolling elements 13, a cage 14, and an annular conductive member 1 according to an embodiment of the present invention. The annular conductive member 1, which is located on the outer side in the width direction BO, is provided with a flow path F in the width direction B, allowing lubricating oil to be supplied from the outside to the inside of the rolling bearing 10. Because the rolling bearing 10 has flow path F penetrating from the inside to the outside, the lubricating oil does not stagnate in the rolling bearing 10 when lubricating oil is supplied to the inside, and therefore an increase in stirring resistance during bearing rotation can be suppressed.

[0024] The rolling elements 13 roll between the raceway surfaces of the outer ring 11 and the inner ring 12. The cage 14 guides the rolling elements 13 at a predetermined interval and holds them rotatably. The outer peripheral portion G of the annular conductive member 1 engages with the engaging groove 11A of the outer ring 11. As a result, the annular conductive member 1 is attached to the outer ring 11 and is installed between the outer ring 11 and the inner ring 12.

[0025] 2-4 includes an annular metal core 3, an annular elastic body 4 made of a rubber material, and conductive fibers 5 that form a conductive texture portion A, which will be described later. The flow path F provided in the annular conductive member 1 is, for example, a through hole 2 formed by a hole 3B in the metal core 3, a hole 4B in the elastic body 4, and a hole H in the conductive texture portion A. The metal core 3 is used to improve the strength of the annular conductive member 1, and therefore may be eliminated depending on the strength required for the annular conductive member 1.

[0026] The rubber material is nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), silicone rubber (VQM), fluororubber (FKM), ethylene propylene diene rubber (EPDM), or the like.

[0027] [Conductive Texture Portion] A conductive texture portion A integrated with conductive fibers 5 is provided in the surface layer portion on one side (inner side BI) in the thickness direction (width direction B) of the elastic body 4. The conductive fibers 5 are carbon fibers or chemical fibers coated with a metal such as copper, nickel, or silver.

[0028] The conductive texture portion A shown in Figures 3-4 is formed by integrating cloth-like conductive fibers into the surface layer portion of the elastic body 4. That is, as shown in the schematic diagram of Figure 5, the conductive fibers 5 integrated into the surface layer portion D on one surface 4A side of the elastic body 4 are cloth-like and consist of a portion 6 protruding from the surface 4A of the elastic body 4 and a portion 7 embedded inside the elastic body 4. Therefore, the portion 6, which is a part of the conductive fibers 5, is exposed from the surface 4A of the elastic body 4.

[0029] As a result, as shown in Fig. 2, with the outer peripheral portion G of the annular conductive member 1 engaged in the engagement groove 11A of the outer ring 11, the conductive fibers 5 (portions 6) exposed from the surface 4A of the elastic body 4 of the outer diameter side conductive texture portion A1, which is the outer diameter side portion of the conductive texture portion A located on the outer peripheral portion 8 of the elastic body 4 (Fig. 3), come into contact with the outer ring 11. Furthermore, the conductive fibers 5 (portions 6) exposed from the surface 4A of the elastic body 4 of the inner diameter side conductive texture portion A2, which is the outer diameter side portion of the conductive texture portion A located on the inner peripheral portion 9 of the elastic body 4 (Fig. 3), come into contact with the outer peripheral surface 12A of the inner ring 12. Therefore, the outer ring 11 and the inner ring 12 are electrically connected by the conductive texture portion A.

[0030] 5 , the structure in which the conductive fibers 5 are integrated into the surface layer D of the elastic body 4 greatly reduces the risk of the conductive fibers 5 peeling off from the elastic body 4. Furthermore, integrating the conductive fibers 5 into the surface layer D of the elastic body 4 and exposing a portion 6 of the conductive fibers 5 from the surface 4A of the elastic body 4 does not present manufacturing difficulties, and the annular conductive member 1 can be easily manufactured, because the conductive fibers 5 are only located in the surface layer D of the elastic body 4, where the position can be relatively easily controlled.

[0031] The conductive fibers 5 integrated into the surface layer D on one surface 4A side of the elastic body 4 in the conductive texture portion A are not limited to a cloth-like shape as shown in Figure 3-5, but may also be a nonwoven fabric-like shape as shown in Figure 6, and the conductive texture portion A may have a planar structure.

[0032] The annular conductive member 1 having such a conductive texture portion A can be easily manufactured by, for example, direct pressure molding as follows.

[0033] That is, first, an annular core metal 3 is set on the lower mold of the molding die so that the hole 3B fits around a shaft that is erected at a predetermined position in the lower mold. An annular pre-vulcanized rubber that will become the elastic body 4 is set on top of that, and an annular sheet of cloth-like or nonwoven conductive fiber 5 is set on top of that so that the hole H fits around the shaft. Next, the upper mold of the molding die is closed and heated, and the pre-vulcanized rubber is vulcanized while pressure is applied to mold it. As a result, the rubber flows into the gaps between the conductive fibers 5 and is molded. After the rubber is vulcanized, the molded product is removed from the molding die to obtain an annular conductive member 1 having a conductive texture portion A as shown in FIG. 3-4 or FIG. 6.

[0034] [Modifications] The annular conductive member 1 of a first modification shown in Figure 7 is an example in which the hole H of Figure 2-3 is not provided in the conductive fibers 5. The annular conductive member 1 of Figure 7 also has the hole 3B of the core 3 and the hole 4B of the elastic body 4 shown in Figure 2-3, and lubricating oil can pass through these holes and the sheet of conductive fibers 5, which is in the form of a cloth or non-woven fabric. Therefore, the annular conductive member 1 has a flow path F that passes through the inside and outside of the rolling bearing 10.

[0035] 7 has a flow path F that passes through the inside and outside of the rolling bearing 10, but the conductive texture portion A does not have a hole H (FIG. 2-3) that communicates with the hole 3B of the core 3 or the hole 4B of the elastic body 4. Therefore, when lubricating oil flows in from outside the rolling bearing 10, foreign matter such as metal powder is filtered out by the sheet of conductive fiber 5 located in the holes 3B and 4B, preventing early damage to the rolling bearing 10.

[0036] The second modified example shown in Fig. 8 differs from the annular conductive member 1 of Fig. 3 in the shape of the conductive texture portion A. That is, the conductive texture portion A in the annular conductive member 1 of Fig. 8 has the same shape as the conductive texture portion A in the annular conductive member 1 of Fig. 3 , namely, an annular intermediate conductive texture portion A0, which is the intermediate portion of the conductive texture portion A in the radial direction R, but has different shapes for the outer diameter side conductive texture portion A1 and the inner diameter side conductive texture portion A2.

[0037] That is, the outer diameter side conductive texture portion A1 and the inner diameter side conductive texture portion A2 are not continuous in the circumferential direction C, but are circumferentially intermittent I portions that are spaced apart in the circumferential direction C.

[0038] The third modified example shown in Figure 9 has the same shape as the annular conductive member 1 in Figure 3, but differs in that the outer diameter side conductive texture portion A1 and the inner diameter side conductive texture portion A2 have cuts E in the radial direction R.

[0039] That is, the outer diameter side conductive texture portion A1 and the inner diameter side conductive texture portion A2 are circumferentially separated type S in which cuts E in the radial direction R are made at predetermined intervals in the circumferential direction C.

[0040] By making the inner diameter side conductive texture portion A2 the circumferentially discontinuous type I or the circumferentially separated type S, the reinforcing effect of the inner diameter side conductive texture portion A2 on the elastic body 4 is suppressed. Therefore, the tightening force applied to the inner ring 12 with which the inner diameter side conductive texture portion A2 comes into contact can be reduced, and the rotational torque of the rolling bearing 10 does not increase.

[0041] By making the outer diameter side conductive texture portion A1 the circumferentially intermittent type I or the circumferentially separated type S, the sheet of conductive fiber of a predetermined shape that becomes the outer diameter side conductive texture portion A1 becomes easier to deform even when molding the outer diameter side conductive texture portion A1 so that it is curved within a molding die, thereby increasing the freedom of shape design.

[0042] The fourth modified example shown in Figure 10 shows an example in which the inner diameter side conductive texture portion A2 contacts the radial surface 12B of the inner ring 12, rather than the outer peripheral surface 12A of the inner ring 12 as shown in Figure 2.

[0043] 11 illustrates an example in which the outer diameter side conductive texture portion A1 contacts the core 3 rather than the outer ring 11 as shown in FIGS. 2 and 10. That is, the engagement portion 3A of the core 3 engages with the engagement groove 11A of the outer ring 11, the outer diameter side conductive texture portion A1 contacts the core 3, and the inner diameter side conductive texture portion A2 contacts the inner ring 12. Therefore, the core 3 and the conductive texture portion A provide electrical continuity between the outer ring 11 and the inner ring 12.

[0044] In an embodiment of the present invention, for example, as shown in Figures 2 and 10, the outer ring 11 and inner ring 12 are electrically connected by the conductive texture portion A. Alternatively, as shown in Figure 11, the outer ring 11 and inner ring 12 are electrically connected by the core bar 3 and the conductive texture portion A. Therefore, in a more preferred embodiment, the rubber material forming the elastic body 4 is not electrically conductive.

[0045] However, depending on the required specifications of the rolling bearing, conductive rubber may be used as the rubber material forming the elastic body 4. For example, if the required specifications require a large interference and there is concern that the inner diameter side conductive texture portion A2 that slides against the inner ring 12 will wear out in the future, it may be possible to use conductive rubber for the elastic body 4. In that case, after the inner diameter side conductive texture portion A2 wears out, the elastic body 4, which is made of conductive rubber, will come into contact with the inner ring 12. However, since the inner diameter side conductive texture portion A2 is located in close proximity to the elastic body 4 that contacts the inner ring 12, the distance over which electricity flows through the conductive rubber (the distance it wears) is short, and the effects of the present invention can be achieved.

[0046] [Major effects] The annular conductive member 1 according to the embodiment of the present invention as described above is provided with flow paths F in the width direction B, so that when the annular conductive member 1 is attached to the outer width direction BO of the rolling bearing 10 ( FIG. 1 ), it has flow paths F that penetrate the inside and outside of the rolling bearing 10. Therefore, it can be attached to and used in a rolling bearing 10 that is used in an environment where lubricating oil is supplied to the inside and a lubricating oil film is always present.

[0047] Furthermore, the conductive fibers 5 (portions 6) exposed from the surface 4A of the elastic body 4 in the inner diameter side conductive texture portion A2 come into contact with the inner ring 12 of the rolling bearing 10. Electrical current flows through the conductive fibers 5 in the inner diameter side conductive texture portion A2 while they are sliding on the inner ring 12, reducing electrical resistance. The conductive fibers 5 sliding on the inner ring 12 scrape off the oil film on the sliding surface, preventing the formation of an oil film on the sliding surface as occurs when a conductive rubber lip slides on the inner ring 12. This stabilizes electrical contact between the conductive fibers 5 and the inner ring 12.

[0048] The above description of the embodiments is given by way of example only and is not intended to be limiting, and various improvements and modifications can be made without departing from the scope of the present invention.

[0049] DESCRIPTION OF SYMBOLS 1 Annular conductive member 2 Through hole 3 Core metal 3A Engagement portion 3B Hole 4 Elastic body 4A Surface 4B Hole 5 Conductive fiber 6 Portion protruding from the surface of the elastic body 7 Portion embedded inside the elastic body 8 Outer peripheral portion of the elastic body 9 Inner peripheral portion of the elastic body 10 Rolling bearing 11 Outer ring 11A Engagement groove 12 Inner ring 12A Outer peripheral surface 12B Radial surface 13 Rolling element 14 Cage A Conductive texture portion A0 Intermediate conductive texture portion A1 Outer diameter side conductive texture portion A2 Inner diameter side conductive texture portion B Width direction BC Width direction center BI Width direction inner BO Width direction outer C Circumferential direction D Surface layer portion E Cut F Flow path G Outer peripheral portion H Hole I Circumferentially interrupted type R Radial direction RI Radial inside RO Radial outside S Circumferential separation type

Claims

1. An annular conductive component that is mounted between the outer ring and inner ring of a rolling bearing and has a flow path that penetrates the inside and outside of the rolling bearing, the annular conductive component having an elastic body made of a rubber material, conductive fibers integrated into a surface layer on one surface of the elastic body, forming a conductive texture portion in which conductive fibers are partly exposed from the surface, an outer diameter side conductive texture portion that is the outer diameter side portion of the conductive texture portion located on the outer periphery of the elastic body, contacts the outer ring, and an inner diameter side conductive texture portion that is the inner diameter side portion of the conductive texture portion located on the inner periphery of the elastic body, contacts the inner ring.

2. An annular conductive component mounted between the outer ring and inner ring of a rolling bearing and having a flow path penetrating the inside and outside of the rolling bearing, the annular conductive component comprising: a core having an engaging portion that engages with the outer ring; and an elastic body made of a rubber material joined to the core; conductive fibers are integrated into a surface layer portion on one surface of the elastic body, forming a conductive texture portion in which some of the conductive fibers are exposed from the surface; an outer diameter side conductive texture portion, which is the outer diameter side portion of the conductive texture portion located on the outer periphery of the elastic body, contacts the core; and an inner diameter side conductive texture portion, which is the inner diameter side portion of the conductive texture portion located on the inner periphery of the elastic body, contacts the inner ring.

3. An annular conductive member according to claim 1 or 2, wherein the inner diameter side conductive texture portion is of a circumferentially discontinuous type that is discontinuous in the circumferential direction, or a circumferentially separated type that has radial cuts at predetermined intervals in the circumferential direction.

4. The annular conductive member according to claim 1, wherein the outer diameter side conductive texture portion is a circumferentially discontinuous type that is discontinuous in the circumferential direction, or a circumferentially separated type that has radial cuts at predetermined intervals in the circumferential direction.

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