Bearing seal

Abstract

[Problem] To achieve, in a bearing seal for preventing electrolytic corrosion of a rolling bearing, reduction in conduction resistance and improvement in conduction stability, as well as easy manufacture. [Solution] A conductive fiber 5 is integrated with a surface layer part on one surface side of an elastic body 4, and a portion of the conductive fiber 5 is exposed from the surface. A portion of the conductive fiber 5 exposed from the surface, located at an outer circumferential part 8 of the elastic body 4 is brought into contact with an outer ring 11, and a portion of the conductive fiber 5 exposed from the surface, located at an inner circumferential part 9 of the elastic body 4 is brought into contact with an inner ring 12. Since the conductive fiber 5 is integrated with the surface layer part of the elastic body 4, the risk of detachment of the conductive fiber 5 from the elastic body 4 becomes significantly small. Since the conductive fiber 5 exposed from the surface of the elastic body 4 slidably comes into contact with the inner ring 12, conduction resistance is reduced and contact for conduction is stabilized. There is no manufacturing difficulty to integrate the conductive fiber 5 with the surface layer part of the elastic body 4 and to expose the portion of the conductive fiber 5 from the surface.

Description

bearing seal

[0001] The present invention relates to a bearing seal 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] As a bearing seal for preventing electrolytic corrosion of such rolling bearings, there is one provided with a conductive material for providing electrical continuity between the outer ring and the inner ring (see, for example, Patent Documents 1 and 2).

[0004] The bearing seal (sealing material A) in Patent Document 1 has a structure in which an elastic body B and a reinforcing material 2 are provided, and an electrically conductive material 3, which is an electrically conductive material, is embedded (FIG. 1) or attached (FIG. 2) to the elastic body B, and the electrically conductive material 3 is connected to a fitting portion A1 that fits onto the outer ring 1b and a sliding contact portion A2 that makes sliding contact with the inner ring 1a. The electrically conductive material 3 is a wire, plate, foil, or the like.

[0005] The bearing seal (seal assembly 04) in Patent Document 2 has a structure in which a seal 05 is made up of an elastomer body 08 and a reinforcing material 09, and a circular conductive element 14 made of the conductive material is affixed to the seal 05, with the outer diameter side of the conductive element 14 contacting the outer ring 02 and the inner diameter side of the conductive element 14 sliding against the inner ring 03 (FIG. 1). The conductive element 14 is made by embedding a conductive fiber fabric made of carbon fiber, a carbon fiber derivative, metal fiber, or filled polymer fiber in an elastomer matrix, i.e., a conductive elastomer.

[0006] Japanese Patent Application Laid-Open No. 62-106125 U.S. Patent No. 11,493,133

[0007] In the case of the bearing seal in Patent Document 1, which has a structure in which an electrically conductive material such as a wire, plate or foil is embedded in an elastic body, it is extremely difficult in terms of manufacturing to have the electrically conductive material penetrate the elastic body in the radial direction and protrude from a predetermined position in the elastic body so that it reliably comes into sliding contact with the inner ring.In the case of the bearing seal in Patent Document 1, which has a structure in which the electrically conductive material is embedded in or attached to the elastic body, a boundary is created between the electrically conductive material and the elastic body, which raises the concern that the electrically conductive material may peel off from the elastic body.

[0008] In the case of a bearing seal having a structure in which a conductive elastomer slides against the inner ring, as in Patent Document 2, the carbon fibers etc. embedded in the elastomer conduct electricity, resulting in high electrical resistance, and in the presence of a lubricant (grease, oil, etc.), an oil film forms on the sliding surface between the conductive elastomer and the inner ring, making contact between the conductive elastomer and the inner ring for electrical conduction unstable.

[0009] An object of the present invention is to provide a bearing seal for preventing electrolytic corrosion of a rolling bearing, which reduces electrical resistance, improves electrical stability, and is easy to manufacture.

[0010] A bearing seal according to a first aspect of the present invention is a bearing seal including an annular seal ring for use in a rolling bearing including an outer ring, an inner ring, and rolling elements, the seal ring having an elastic body made of a rubber material. Conductive fibers are integrated into a surface layer portion on one surface of the elastic body, and some of the conductive fibers are exposed from the surface. The conductive fibers exposed from the surface of the outer peripheral part of the elastic body contact the outer ring, and the conductive fibers exposed from the surface of the inner peripheral part of the elastic body contact the inner ring.

[0011] A bearing seal according to a second aspect of the present invention is a bearing seal including an annular seal ring for use in a rolling bearing including an outer ring, an inner ring, and rolling elements, the seal ring having a core metal having an engagement portion that engages with the outer ring, and an elastic body joined to the core metal. Conductive fibers are integrated into a surface layer portion on one surface side of the elastic body, and some of the conductive fibers are exposed from the surface. The conductive fibers exposed from the surface of the outer peripheral part of the elastic body contact the core metal, and the conductive fibers exposed from the surface of the inner peripheral part of the elastic body contact the inner ring.

[0012] As described above, because the conductive fibers are integrated into a surface layer portion on one surface of the elastic body of the bearing seal of the present invention, there is little concern that the conductive fibers will peel off from the elastic body. Furthermore, because the conductive fibers exposed from this surface of the elastic body are in sliding contact with the inner ring, electrical resistance is low, and because an oil film does not form on the sliding surface between the conductive elastomer and the inner ring in the presence of a lubricant, contact for electrical conduction is stable. Furthermore, because the conductive fibers are integrated into a surface layer portion on one surface of the elastic body of the bearing seal and portions of the conductive fibers are exposed from this surface, there are no manufacturing difficulties and the bearing seal is easy to manufacture, as the conductive fibers are only located in the surface layer portion of the elastomer, where their position is relatively easy to control.

[0013] Figure 2 is an enlarged longitudinal cross-sectional view of a main part of a rolling bearing equipped with a bearing seal according to an embodiment of the present invention. Figure 3 is an enlarged longitudinal cross-sectional view of a main part showing the periphery of one of the bearing seals in the rolling bearing of Figure 1. Figure 4 is a schematic view showing a conductive texture formed by integrating cloth-like conductive fibers into the surface layer part of an elastic body. Figure 5 is a schematic view showing an enlarged cross-section of the conductive texture. Figure 6 is a schematic view showing a conductive texture formed by integrating non-woven cloth-like conductive fibers into the surface layer part of an elastic body. Figure 7 is an enlarged longitudinal cross-sectional view of a main part showing the periphery of a bearing seal of a first modified example. Figure 8 is an enlarged longitudinal cross-sectional view of a main part showing the periphery of a bearing seal of a second modified example. Figure 9 is an enlarged longitudinal cross-sectional view of a main part showing the periphery of a bearing seal of a third modified example.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] In this specification, the direction parallel to the direction of the central axis of rotation of the rolling bearing is referred to as the "width direction" (see, for example, arrow B in Figure 1), and the direction perpendicular to the direction of the central axis of rotation is referred to as the "radial direction" (see, for example, arrow R in Figure 1).

[0016] In this specification, the width direction approaching the widthwise center of the rolling bearing (e.g., symbol C in Figure 1) is referred to as the "widthwise inward" (e.g., see arrow BI in Figure 1), the width direction moving away from the widthwise center is referred to as the "widthwise outward" (e.g., see arrow BO in Figure 1), the radial direction approaching the rotational center axis is referred to as the "radial direction inward" (e.g., 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" (e.g., see arrow RO in Figure 1).

[0017] 1 comprises an outer ring 11, an inner ring 12, rolling elements 13, a cage 14, and a bearing seal 1. 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 periphery of the bearing seal 1 engages with an engagement groove 11A in the outer ring 11, and the inner periphery of the bearing seal 1 contacts the inner surface of a seal groove 12A in the inner ring 12.

[0018] 1 and 2 includes an annular seal ring 2. The seal ring 2 has an annular core 3 and an annular elastic body 4 made of a rubber material. The core 3 is used to improve the strength of the bearing seal 1. Conductive fibers 5 are integrated into the surface layer of the elastic body 4 on one side (inner side BI) in the thickness direction (width direction B). The conductive fibers 5 are carbon fibers or chemical fibers coated with a metal such as copper, nickel, or silver.

[0019] As shown in the schematic diagrams of Figures 3 and 4, the conductive fibers 5 integrated into the surface layer D on one surface 4A 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 within the elastic body 4. Therefore, the portion 6, which is a part of the conductive fibers 5, is exposed from the surface 4A. In this way, the conductive fibers 5 are integrated into the surface layer D on one surface 4A of the elastic body 4, and a conductive texture A having conductivity is formed by the exposed portion of the conductive fibers 5. The conductive fibers 5 integrated into the surface layer D on one surface 4A of the elastic body 4 may be in the form of a nonwoven fabric as shown in Figure 5, as long as the conductive fibers 5 have a planar structure. The actual shape of the conductive texture A in the bearing seal 1 is annular.

[0020] The bearing seal 1 having such a conductive texture A can be easily manufactured by, for example, direct pressure molding as follows.

[0021] That is, first, an annular core metal 3 is set on 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. Next, the upper mold is closed and heated, and the pre-vulcanized rubber is vulcanized while being molded under pressure. As a result, the rubber flows into the gaps between the conductive fibers 5 and is molded. After the rubber has been vulcanized, the molded product is removed from the mold to obtain a bearing seal 1 having the conductive texture A shown in Figure 2.

[0022] 1 and 2 , in the bearing seal 1, the conductive fibers 5 exposed from the surface of the outer circumferential portion 8 of the elastic body 4 contact the outer ring 11, and the conductive fibers 5 exposed from the surface of the inner circumferential portion 9 of the elastic body 4 contact the inner ring 12. This provides electrical continuity between the outer ring 11 and the inner ring 12. In the example shown in Figures 1 and 2 , the conductive fibers 5 contacting the inner ring 12 contact the inner ring 12 in the width direction B.

[0023] [Modification] Depending on the strength required for the bearing seal 1, the metal core 3 shown in Fig. 2, which is used to improve the strength of the bearing seal 1, may be eliminated. Fig. 6 shows an example of a bearing seal 1 without the metal core 3.

[0024] The bearing seal 1 having the conductive texture A shown in FIG. 6 can be easily manufactured by, for example, direct pressure molding as follows.

[0025] That is, first, a circular pre-vulcanized rubber that will become the elastic body 4 is placed on the lower mold, and then a circular sheet of conductive fiber 5 in the form of a cloth or nonwoven fabric is placed on top of that. Next, the upper mold is closed and heated, and the pre-vulcanized rubber is molded under pressure while being vulcanized. As a result, the rubber flows into the gaps between the conductive fibers 5 and is molded. After the rubber has been vulcanized, the molded product is removed from the mold, yielding a bearing seal 1 having the conductive texture A shown in Figure 6.

[0026] Instead of the configuration in which the conductive fibers 5 contacting the inner ring 12 contact the inner ring 12 in the width direction B as shown in Figures 2 and 6, the conductive fibers 5 contacting the inner ring 12 may be configured to contact the outer peripheral surface 12B of the inner ring 12 in the radial direction R as shown in Figure 7.

[0027] The modified example shown in Figure 8 shows an example in which the conductive fiber 5 is not brought into contact with the outer ring 11, but the core 3 is brought into contact with the outer ring 11 with the engaging portion 3A of the core 3 engaged in the engaging groove 11A of the outer ring 11, thereby establishing electrical conductivity between the core 3 and the outer ring 11.

[0028] 8 , the seal ring 2 is made up of a core 3 having an engaging portion 3A that engages with the outer ring 11, and an elastic body 4 joined to the core 3. Conductive fibers 5 are integrated into a surface layer portion on one surface of the elastic body 4, with some of the conductive fibers 5 exposed from the surface, and a conductive texture A having conductivity is formed on the surface side of the elastic body 4. The conductive fibers 5 exposed from the surface of the outer peripheral portion 8 of the elastic body 4 contact the core 3, and the conductive fibers 5 exposed from the surface of the inner peripheral portion 9 of the elastic body 4 contact the inner ring 12.

[0029] The bearing seal 1 having the conductive texture A shown in FIG. 8 can be easily manufactured by, for example, direct pressure molding as follows.

[0030] That is, first, an annular core metal 3 is set on the lower mold, then an annular sheet of cloth-like or nonwoven conductive fiber 5 is set on top of that, and then an annular pre-vulcanized rubber that will become the elastic body 4 is set on top of that. Next, the upper mold is closed and heated, and the pre-vulcanized rubber is molded under pressure while being vulcanized. As a result, the rubber flows into the gaps between the conductive fibers 5 and is molded. After the rubber has been vulcanized, the molded product is removed from the mold to obtain a bearing seal 1 having the conductive texture A shown in Figure 8.

[0031] 2, 6 and 7, the conductive fibers 5 exposed from one surface of the outer periphery 8 of the elastic body 4 contact the outer ring 11, and in the example of Fig. 8, the conductive fibers 5 exposed from one surface of the outer periphery 8 of the elastic body 4 contact the metal core 3, and the metal core 3 contacts the outer ring 11. Therefore, conductivity between the conductive fibers 5 and the outer ring 11 is ensured.

[0032] In the bearing seal 1 of Figures 2, 6, 7 and 8, the conductive texture A is annular in shape, and the conductive fibers 5 on the inner diameter side of the conductive texture A slide against the inner ring 12, ensuring stable conductivity regardless of which circumferential position of the conductive texture A comes into contact with the inner ring 12.

[0033] Therefore, the bearing seal 1 having the conductive texture A ensures stable and reliable conduction between the outer ring 11 and the inner ring 12, so that when a potential difference occurs between the outer ring 11 and the inner ring 12, current flows via the conductive texture A, preventing charging of the rolling bearing 10 and the occurrence of sparks. As a result, the electrolytic corrosion resistance of the rolling bearing 10 is improved.

[0034] In the bearing seal 1 of Figures 2, 6, 7 and 8, the conductive fibers 5 are integrated into the surface layer on one surface side of the elastic body 4, so there is very little concern that the conductive fibers 5 will peel off from the elastic body 4.

[0035] In the bearing seal 1 in FIGS. 2 , 6 , 7 and 8 , the conductive fibers 5 exposed from one surface of the elastic body 4 are in sliding contact with the inner ring 12, reducing electrical resistance and stabilizing contact for electrical conduction because no oil film is formed, as is the case on the sliding surfaces between the conductive elastomer and inner ring in the presence of a lubricant.

[0036] In the bearing seal 1 of Figures 2, 6, 7 and 8, the conductive fibers 5 are integrated into the surface layer on one surface side of the elastic body 4 of the bearing seal 1, and part of the conductive fibers 5 is exposed from the surface. This does not pose manufacturing difficulties, and makes it easy to manufacture the bearing seal 1, because the conductive fibers 5 are only present in the surface layer of the elastic body 4, where the position is relatively easy to control.

[0037] In the bearing seal 1 of Figures 2, 6, 7 and 8, it is not the elastic body 4 that slides on the inner ring 12, but rather the conductive fibers 5 exposed from the surface of the elastic body 4, and therefore conductivity can be obtained with lower torque than in a configuration in which a conductive elastomer slides on the inner ring.

[0038] 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.

[0039] DESCRIPTION OF SYMBOLS 1 Bearing seal 2 Seal ring 3 Core metal 3A Engagement portion 4 Elastic body 4A Surface 5 Conductive fiber 6 Portion protruding from the surface of the elastic body 7 Portion embedded inside the elastic body 8 Outer peripheral portion 9 Inner peripheral portion 10 Rolling bearing 11 Outer ring 11A Engagement groove 12 Inner ring 12A Seal groove 12B Outer peripheral surface 13 Rolling element 14 Cage A Conductive texture B Width direction BI Width direction inner side BO Width direction outer side C Width direction center D Surface layer portion R Radial direction RI Radial direction inner side RO Radial direction outer side

Claims

1. A bearing seal including an annular seal ring for use in a rolling bearing which includes an outer ring, an inner ring, and rolling elements, wherein the seal ring has an elastomer made of a rubber material, conductive fibers are integrated into a surface layer on one surface of the elastomer and some of the conductive fibers are exposed from the surface, the conductive fibers exposed from the surface of the outer periphery of the elastomer contacts the outer ring, and the conductive fibers exposed from the surface of the inner periphery of the elastomer contacts the inner ring.

2. A bearing seal including an annular seal ring for use in a rolling bearing which includes an outer ring, an inner ring and rolling elements, wherein the seal ring has a core bar having an engagement portion which engages with the outer ring, and an elastomer joined to the core bar, conductive fibers are integrated into a surface layer portion on one surface side of the elastomer, some of the conductive fibers are exposed from the surface, the conductive fibers exposed from the surface of the outer periphery of the elastomer contacts the core bar, and the conductive fibers exposed from the surface of the inner periphery of the elastomer contacts the inner ring.

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