Bearing seal

Abstract

[Problem] To provide a bearing seal for preventing electric corrosion of a rolling bearing, wherein conductivity is stabilized, excellent conduction is obtained, and the space requirements and manufacturing costs for the bearing seal do not increase. [Solution] A bearing seal 1 used in a rolling bearing including an outer ring 11, an inner ring 12, and rolling elements 13, wherein the bearing seal 1 is provided with an outer-ring-side metal plate 2 attached to the outer ring 11, an inner-ring-side metal plate 3 attached to the inner ring 12, and a conductive felt 4 formed by entangling conductive fibers together. The outer-ring-side metal plate 2 has an outer-ring-side base end part 5 in contact with an inner peripheral surface 11A of the outer ring 11, and a first annular part 6 extending radially inward RI from the outer-ring-side base end part 5. The inner-ring-side metal plate 3 has an inner-ring-side base end part 7 in contact with an outer peripheral surface 12A of the inner ring 12, and a second annular part 8 extending radially outward RO from the inner-ring-side base end part 7 and facing the first annular part 6. The annular felt 4 is held between the first annular part 6 and the second annular part 8.

Description

Bearing seal

[0007]

[0001] The present invention relates to a bearing seal for preventing electrical erosion of a rolling bearing.

[0002] For example, in a motor and a speed reducer unit of an electric vehicle, and a motor driven by an inverter other than an electric vehicle, current may leak and flow to the rotating shaft. In that case, in the rolling bearing that supports the rotating shaft, the lubricating oil film is broken and current flows between the outer ring and the inner ring, and the rolling surface of the rolling element may be damaged by an arc.

[0003] As a bearing seal for preventing such electrical erosion of a rolling bearing, there is one in which a conductive member is provided between an outer ring side metal plate attached to the outer ring and an inner ring side metal plate attached to the inner ring (see, for example, Patent Documents 1-4).

[0004] The conductive member in the bearing seal of Patent Document 1 is a solid lubricant having conductivity. Resin powder as a thickener is mixed with grease, and a carbon filler as a conductive material is further added, and it is put into a mold and maintained at a predetermined temperature or higher for a while to be formed into an arbitrary three-dimensional shape following the mold. The solid lubricant is held on one of the outer ring side metal plate and the inner ring side metal plate and abuts against the other of the outer ring side metal plate and the inner ring side metal plate.

[0005] The conductive member in the bearing seal of Patent Document 2 is conductive grease in which a conductive carbon filler or metal powder is dispersed in the grease. The configuration of the bearing seal in FIG. 1 of Patent Document 2 is provided with a lip at the inner diameter side end of the outer ring side metal plate, the tip of which contacts the inner ring side metal plate, and at the outer diameter side end of the inner ring side metal plate, a lip the tip of which contacts the outer ring side metal plate is provided. The conductive grease is enclosed in the sealed space formed by the above configuration.

[0006] The conductive member in the bearing seal of Patent Document 3 is a sub-rolling element made of a metal material. The sub-rolling element contacts and rolls on the outer ring side metal plate and the inner ring side metal plate and is held by a cage so as to maintain a certain interval.

[0007] The conductive member in the bearing seal of Patent Document 4 is a conductive flexible rolling element, which is a ball that is both conductive and flexible, having conductivity imparted by the addition of a conductive filler, such as conductive rubber or conductive resin. The flexible rolling element rolls in contact with the outer ring side metal plate and the inner ring side metal plate and is held by a cage to maintain a constant distance between them.

[0008] Japanese Patent Publication No. 2021-134812, Japanese Patent No. 7488447, Japanese Patent Publication No. 2023-184282, Japanese Patent Publication No. 2022-118903

[0009] In conventional bearing seals for preventing electrolytic corrosion of rolling bearings, as described above, conductive members in which conductive fillers or the like are added and dispersed, as in Patent Documents 1, 2, and 4, have unstable conductivity and limitations in conductivity.

[0010] In other words, in conductive materials that disperse conductive fillers, conductivity is achieved by the randomly dispersed conductive fillers in the matrix forming conductive paths. However, this method results in unstable conductivity due to the random dispersion. Furthermore, there are limitations on the amount of conductive fillers that can be added in order to maintain the function of the matrix. For example, in the case of conductive rubber, the amount of conductive fillers must be kept below a certain level to maintain the elasticity of the rubber. Consequently, conductivity is limited, and good conductivity cannot be obtained.

[0011] In the conventional bearing seals for preventing galvanic corrosion of rolling bearings, as described in Patent Documents 3 and 4, a conductive member consisting of a separate rolling element (secondary rolling element) that is conductive and distinct from the main rolling element increases the thickness of the secondary rolling element, which rolls in contact with the outer ring side metal plate and the inner ring side metal plate, in the direction parallel to the rotational axis of the rolling bearing, thus increasing the required space for the bearing seal. Furthermore, a large number of conductive secondary rolling elements are required, as well as a cage to hold the secondary rolling elements at a constant interval, thus increasing manufacturing costs.

[0012] The present invention aims to provide a bearing seal for preventing electrolytic corrosion of rolling bearings that offers stable conductivity, good electrical conductivity, and does not increase the required space or manufacturing cost of the bearing seal.

[0013] A bearing seal according to a first aspect of the present invention is a bearing seal used in a rolling bearing including an outer ring, an inner ring, and rolling elements, comprising an outer ring side metal plate attached to the outer ring, an inner ring side metal plate attached to the inner ring, and a conductive felt formed by intertwining conductive fibers. The outer ring side metal plate has an outer ring side base end that contacts the inner circumferential surface of the outer ring and a first annular portion extending radially inward from the outer ring side base end, and the inner ring side metal plate has an inner ring side base end that contacts the outer circumferential surface of the inner ring and a second annular portion extending radially outward from the inner ring side base end and facing the first annular portion, and the conductive felt is sandwiched between the first annular portion and the second annular portion.

[0014] In the bearing seal relating to the first aspect, the conductive felt is formed by intertwining conductive fibers, and since the material itself is conductive, it does not require the dispersion of conductive materials such as carbon fillers. Therefore, the conductive felt can exhibit stable and high conductivity compared to conductive solid lubricants, conductive greases, conductive rubber, and conductive resins.

[0015] Because the conductive felt has internal cavities, lubricants such as lubricating oil and grease swell, thus reducing sliding resistance. Since the conductive felt is formed by intertwining conductive fibers, the actual contact area between the conductive felt and the outer ring side metal plate or the inner ring side metal plate during sliding is small. Therefore, the oil film is scraped off by the fine conductive fibers where surface pressure is concentrated, making it possible to achieve both sliding properties and contact for electrical conductivity. Consequently, the bearing seal can be used even in the presence of the lubricant.

[0016] Because the conductive felt is located between the outside of the rolling bearing and the rolling elements, foreign matter that enters the rolling bearing from the outside along with the lubricating oil can be filtered out by the conductive felt, and the lubricating oil necessary for lubricating the inside of the rolling bearing has a filter function that allows it to pass through the conductive felt.

[0017] The conductive felt only needs to be shaped to be sandwiched between the first annular portion of the outer ring side metal plate attached to the outer ring of the rolling bearing and the second annular portion of the inner ring side metal plate attached to the inner ring of the rolling bearing. This allows for a reduction in the thickness in the direction parallel to the rotational axis of the rolling bearing, and eliminates the need for a cage to maintain the spacing between the auxiliary rolling elements.

[0018] According to the bearing seal of the first aspect, the conductive felt having the above-mentioned effect is sandwiched between the first and second annular portions, and the outer ring and the inner ring are electrically connected. This ensures stable conductivity and good conductivity, while also preventing an increase in the required space and manufacturing cost of the bearing seal.

[0019] A bearing seal according to a second aspect of the present invention is a bearing seal according to a first aspect, wherein the radially inward edge of the first annular portion is bent toward the second annular portion to form an inner diameter side retaining portion, and the radially outward edge of the second annular portion is bent toward the first annular portion to form an outer diameter side retaining portion.

[0020] According to the bearing seal relating to the second aspect, the conductive felt can be prevented from coming off by the inner diameter side retaining portion and the outer diameter side retaining portion. Therefore, the conductive felt can be stably held between the first annular portion and the second annular portion without having to attach the conductive felt to the first annular portion or the second annular portion.

[0021] A bearing seal according to a third aspect of the present invention is a bearing seal according to a first or second aspect, wherein the conductive fiber is a carbon fiber.

[0022] In the bearing seal relating to the third aspect, the conductive felt is formed by intertwining carbon fibers themselves. The conductive felt, formed by intertwining carbon fibers themselves, has the required restoring force against deformation. Therefore, when the conductive felt is compressed by being sandwiched between the first and second annular portions, the required reaction force is generated toward the first and second annular portions due to the restoring force, in proportion to the amount of compression. Consequently, the conductive felt can follow deformation (positional displacement, etc.) due to eccentricity during the rotational motion of the rolling bearing, and makes more stable contact with the first and second annular portions, resulting in more stable and good conductivity.

[0023] A bearing seal according to a fourth aspect of the present invention, in a bearing seal according to a first or second aspect, comprises an annular elastic lip made of rubber material, which is a contact-type or non-contact-type seal, provided in the annular gap in the space extending from the conductive felt to the rolling element.

[0024] According to the bearing seal relating to the fourth aspect, since the contact-type or non-contact-type seal made of the elastic lip is provided in the annular gap in the space extending from the conductive felt to the rolling element, wear particles of the conductive felt and other foreign matter can be prevented or reduced from entering the inside of the rolling bearing.

[0025] A bearing seal according to a fifth aspect of the present invention, in a bearing seal according to a first or second aspect, comprises an annular elastic lip made of rubber material that serves as a contact-type or non-contact-type seal, provided in an annular gap in the space extending from the outside of the rolling bearing to the conductive felt.

[0026] According to the bearing seal relating to the fifth aspect, since the contact-type or non-contact-type seal made of the elastic lip is provided in the annular gap in the space extending from the outside of the rolling bearing to the conductive felt, it is possible to prevent or reduce foreign matter from the outside of the rolling bearing from reaching the conductive felt, thereby greatly increasing the effect of preventing or reducing the foreign matter from entering the inside of the rolling bearing.

[0027] As described above, the bearing seal according to the present invention provides a bearing seal that prevents electrolytic corrosion of rolling bearings, offers stable conductivity and good electrical conductivity, and does not increase the required space or manufacturing cost of the bearing seal.

[0028] Figure 1 is a partial cross-sectional perspective view of a rolling bearing equipped with a bearing seal according to an embodiment of the present invention. Figure 2 is an enlarged longitudinal cross-sectional view of the main part of the rolling bearing shown in Figure 1. Figure 3 is an enlarged view of the main part showing the area enclosed by the dashed line in Figure 2. Figure 4 is a partial cross-sectional perspective view showing the outer ring side metal plate and conductive felt removed, showing an example in which a simplified annular conductive felt is bonded to the first annular portion of the outer ring side metal plate. Figure 5 is an enlarged view of the main part similar to Figure 3, showing a first modified example in which retainers for the conductive felt are provided at the first and second annular portions. Figure 6 is a partial cross-sectional perspective view similar to Figure 1, showing a second modified example equipped with an elastic lip that seals the annular gap in the space from the conductive felt to the rolling element. Figure 6 is an enlarged longitudinal cross-sectional view of the main part of the rolling bearing shown in Figure 6. Figure 7 is an enlarged view of the main part showing the area enclosed by the dashed line in Figure 7. Figure 8 is an enlarged view of the main part similar to Figure 8, showing a third modified example equipped with an elastic lip that seals the annular gap in the space from the outside of the rolling bearing to the conductive felt.

[0029] Embodiments of the present invention will be described below with reference to the drawings.

[0030] In this specification, the direction parallel to the rotational axis of a rolling bearing (for example, see reference numeral O in Figure 1) is referred to as the "width direction" (for example, see arrow B in Figures 1 and 2), and the direction perpendicular to the rotational axis is referred to as the "radial direction" (for example, see arrow R in Figure 2). The "circumferential direction" (for example, see arrow C in Figure 1) is defined with respect to the direction of the rotational axis.

[0031] In this specification, the width direction approaching the center of the rolling bearing in the width direction (for example, reference numeral D in Figure 2) is referred to as the "inward width direction" (for example, see arrow BI in Figure 2), the width direction moving away from the center in the width direction is referred to as the "outward width direction" (for example, see arrow BO in Figure 2), the radial direction approaching the rotational axis is referred to as the "inward radial direction" (for example, see arrow RI in Figure 2), and the radial direction moving away from the rotational axis is referred to as the "outward radial direction" (for example, see arrow RO in Figure 2).

[0032] [Rolling Bearing] The rolling bearing A shown in Figure 1-2 comprises an outer ring 11, an inner ring 12, rolling elements 13, a cage 14, and a bearing seal 1 according to an embodiment of the present invention. The rolling elements 13 roll between the raceway surface of the outer ring 11 and the raceway surface of the inner ring 12. The cage 14 guides the rolling elements 13 at predetermined intervals and holds them rotatably. The bearing seal 1 is positioned on the widthwise outward BO of the rolling elements 13 and the cage 14.

[0033] [Bearing seal] The bearing seal 1 shown in Figure 1-3 comprises an outer ring side metal plate 2 attached to the outer ring 11, an inner ring side metal plate 3 attached to the inner ring 12, and a conductive felt 4 formed by intertwining conductive fibers.

[0034] The conductive felt 4 is, for example, made by compressing conductive fibers that have been entangled using a needle into a sheet, or by combining conductive short fibers dispersed in a liquid and formed into a sheet.

[0035] The conductive fibers are, for example, carbon fibers, but may also be metal-coated chemical fibers. Copper, silver, and / or nickel can be used as the metal coating for the chemical fibers. Carbon fibers can also be reinforced by mixing them with polyester resin or polyvinyl chloride resin.

[0036] Refer to Figures 1 and 3. The outer ring side metal plate 2 is annular and has an outer ring side base end 5 that contacts the inner circumferential surface 11A of the outer ring 11, and a first annular portion 6 that extends radially inward RI from the outer ring side base end 5. The inner ring side metal plate 3 is annular and has an inner ring side base end 7 that contacts the outer circumferential surface 12A of the inner ring 12, and a second annular portion 8 that extends radially outward RO from the inner ring side base end 7 and faces the first annular portion 6. The first annular portion 6 of the outer ring side metal plate 2 is located at BI in the width direction of the second annular portion 8 of the inner ring side metal plate 3.

[0037] As shown in Figure 3, the conductive felt 4 is held between the first annular portion 6 of the outer ring side metal plate 2 and the second annular portion 8 of the inner ring side metal plate 3, and is compressed in the width direction B, and is held between the first annular portion 6 and the second annular portion 8. Therefore, the outer ring 11 and the inner ring 12 are electrically connected by the outer ring side metal plate 2, the inner ring side metal plate 3 and the conductive felt 4.

[0038] The conductive felt 4 may be bonded to either the first annular portion 6 of the outer ring metal plate 2 or the second annular portion 8 of the inner ring metal plate 3. Figure 4 shows an example where the conductive felt 4 is bonded to the first annular portion 6 of the outer ring metal plate 2. The conductive felt 4 is, for example, an annular shape that is continuous in the circumferential direction C as shown in Figure 4, but it may also be discontinuous in the circumferential direction C.

[0039] [Effects] In the bearing seal 1 according to this embodiment, the conductive felt 4 is formed by intertwining conductive fibers, and since the material itself is conductive, it does not require the dispersion of conductive materials such as carbon fillers. Therefore, the conductive felt 4 can exhibit stable and high conductivity compared to conductive solid lubricants, conductive greases, conductive rubber, and conductive resins.

[0040] Because the conductive felt 4 has internal cavities, lubricants such as lubricating oil and grease swell, thus reducing sliding resistance. Since the conductive felt 4 is formed by intertwining conductive fibers, the actual contact area between the conductive felt 4 and the outer ring side metal plate 2 or the inner ring side metal plate 3 during sliding is small. Therefore, the oil film is scraped off by the fine conductive fibers where surface pressure is concentrated, making it possible to achieve both sliding properties and contact for electrical conductivity. Consequently, the bearing seal 1 can be used even in the presence of the lubricant.

[0041] Since there is a conductive felt 4 between the outside of the rolling bearing A and the rolling elements 13, foreign matter that enters from the outside of the rolling bearing A along with the lubricating oil can be filtered out by the conductive felt 4, and the conductive felt 4 also functions as a filter that allows the lubricating oil necessary for lubricating the inside of the rolling bearing A to pass through.

[0042] The conductive felt 4 only needs to be shaped to be sandwiched between the first annular portion 6 of the outer ring side metal plate 2 attached to the outer ring 11 of the rolling bearing A, and the second annular portion 8 of the inner ring side metal plate 3 attached to the inner ring 12 of the rolling bearing A. This allows for a reduction in the thickness in the width direction B, and eliminates the need for a cage to maintain the spacing between the auxiliary rolling elements, as described in Patent Documents 3 and 4.

[0043] Since the outer ring 11 and the inner ring 12 are electrically conductive in a state where the conductive felt 4 having the above-described effects is sandwiched between the first annular portion 6 and the second annular portion 8, the conductivity is stable and good conduction can be obtained, and the required space and manufacturing cost of the bearing seal 1 do not increase.

[0044] When the conductive felt 4 is formed by intertwining the carbon fibers themselves, the conductive felt 4 formed by intertwining the carbon fibers themselves has a required restoring force against deformation. Therefore, according to the amount of compression when the conductive felt 4 is sandwiched between the first annular portion 6 and the second annular portion 8 and compressed, a required reaction force toward the first annular portion 6 and the second annular portion 8 is generated by the restoring force. Therefore, the conductive felt 4 follows even the deformation (such as displacement) due to eccentricity or the like during the rotational movement of the rolling bearing A, and contacts the first annular portion 6 and the second annular portion 8 more stably, so that more stable and good conduction can be obtained.

[0045] [First Modified Example]In the first modified example of the bearing seal 1 shown in FIG. 5, the radially inner RI side edge portion 6A of the first annular portion 6 of the outer ring side metal plate 2 is formed as an inner diameter side retaining portion G1 bent outward in the width direction BO, and the radially outer RO side edge portion 8A of the second annular portion 8 of the inner ring side metal plate 3 is formed as an outer diameter side retaining portion G2 bent inward in the width direction BI.

[0046] In the conductive felt 4 sandwiched between the first annular portion 6 and the second annular portion 8, the movement of the conductive felt 4 in the radially inner RI direction is restricted by the inner diameter side retaining portion G1, and the movement of the conductive felt 4 in the radially outer RO direction is restricted by the outer diameter side retaining portion G2. Therefore, the conductive felt 4 can be prevented from coming off. Therefore, the state in which the conductive felt 4 is sandwiched between the first annular portion 6 and the second annular portion 8 can be stably maintained without attaching the conductive felt 4 to the first annular portion 6 or the second annular portion 8.

[0047] [Second Modified Example] In the second modified example of the bearing seal 1 shown in FIGS. 6 to 8, an annular elastic lip 10A made of a rubber material is provided in an annular gap 9A (FIG. 8) in the space extending from the conductive felt 4 to the rolling elements 13. 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.

[0048] In the example shown in FIG. 8, the elastic lip 10A is attached to the edge E on the radially inner RI side of the outer ring side metal plate 2, and the tip of the elastic lip 10A is in sliding contact with the inner ring side base end portion 7 of the inner ring side metal plate 3, and it is a contact type seal that closes the annular gap 9A. The elastic lip 10A may be attached to the inner ring side metal plate 3, and in that case, the tip of the elastic lip 10A is in sliding contact with the outer ring side metal plate 2.

[0049] The elastic lip 10A is not limited to a contact type seal and may be a non-contact type seal.

[0050] According to the bearing seal 1 provided with the elastic lip 10A, since a contact type or non-contact type seal by the elastic lip 10A is provided in the annular gap 9A, it is possible to prevent or reduce the wear powder of the conductive felt 4 and other foreign matters from entering the inside of the rolling bearing A.

[0051] [Third Modified Example] In the third modified example of the bearing seal 1 shown in FIG. 9, an annular elastic lip 10B made of a rubber material is provided in an annular gap 9B in the space extending from the outside of the rolling bearing A to the conductive felt 4. The rubber material is the same as that of the elastic lip 10A in the second modified example.

[0052] In the example shown in FIG. 9, the elastic lip 10B is attached to the edge F on the radially outer RO side of the inner ring side metal plate 3, and the tip of the elastic lip 10B is in sliding contact with the outer ring side base end portion 5 of the outer ring side metal plate 2, and it is a contact type seal that closes the annular gap 9B. The elastic lip 10B may be attached to the outer ring side metal plate 2, and in that case, the tip of the elastic lip 10B is in sliding contact with the inner ring side metal plate 3.

[0053] The elastic lip 10B is not limited to a contact type seal and may be a non-contact type seal.

[0054] With the bearing seal 1 equipped with an elastic lip 10B, since a contact-type or non-contact-type seal by the elastic lip 10B is provided in the annular gap 9B, it is possible to prevent or reduce foreign matter from the outside of the rolling bearing A from reaching the conductive felt 4, thereby greatly increasing the effect of preventing or reducing the foreign matter from entering the inside of the rolling bearing A.

[0055] All embodiments described above are illustrative and not limiting. Various improvements and modifications can be made without departing from the scope of the present invention.

[0056] 1 Bearing seal 2 Outer ring side metal plate 3 Inner ring side metal plate 4 Conductive felt 5 Outer ring side base end 6 First annular portion 6A Radially inward edge 7 Inner ring side base end 8 Second annular portion 8A Radially outward edge 9A Annular gap in the space from conductive felt to rolling element 9B Annular gap in the space from the outside of the rolling bearing to the conductive felt 10A, 10B Elastic lip 11 Outer ring 11A Inner circumferential surface 12 Inner ring 12A Outer circumferential surface 13 Rolling element 14 Cage A Rolling bearing B Width direction BI Width direction inward BO Width direction outward C Circumferential direction D Width direction center E, F Edge G1 Inner diameter side retaining portion G2 Outer diameter side retaining portion O Rotational axis R Radial direction RI Radial inside RO Radial outside

Claims

1. A bearing seal for use in a rolling bearing including an outer ring, an inner ring, and rolling elements, comprising: an outer ring side metal plate attached to the outer ring; an inner ring side metal plate attached to the inner ring; and a conductive felt formed by intertwining conductive fibers, wherein the outer ring side metal plate has an outer ring side base end that contacts the inner circumferential surface of the outer ring and a first annular portion extending radially inward from the outer ring side base end; the inner ring side metal plate has an inner ring side base end that contacts the outer circumferential surface of the inner ring and a second annular portion extending radially outward from the inner ring side base end and facing the first annular portion, and the annular felt is sandwiched between the first annular portion and the second annular portion.

2. The bearing seal according to claim 1, wherein the radially inward edge of the first annular portion is bent toward the second annular portion to form an inner diameter retaining portion, and the radially outward edge of the second annular portion is bent toward the first annular portion to form an outer diameter retaining portion.

3. The bearing seal according to claim 1 or 2, wherein the conductive fiber is a carbon fiber.

4. The bearing seal according to claim 1 or 2, further comprising an annular elastic lip made of rubber material, which is provided in the annular gap in the space extending from the conductive felt to the rolling element, and which serves as a contact-type or non-contact-type seal.

5. The bearing seal according to claim 1 or 2, comprising an annular elastic lip made of rubber material, which is a contact-type or non-contact-type seal, provided in an annular gap in the space extending from the outside of the rolling bearing to the conductive felt.

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