Insulated rolling bearing, method for manufacturing an insulated rolling bearing, and insulating cover member for a rolling bearing

Abstract

To provide insulated rolling bearings that are easy to ensure the quality of and are low-cost. [Solution] In an insulated rolling bearing, the insulating cover member 5 is made of rubber material.

Description

Technical Field

[0001] This invention relates to a rolling bearing with insulation, a method for manufacturing the rolling bearing with insulation, and an insulation cover member used for the rolling bearing with insulation.

Background Art

[0002] In rolling bearings that support the rotating shaft of an electric motor for driving an electric vehicle such as a battery-powered electric vehicle (EV) or a hybrid vehicle (HEV), or in rolling bearings that support the gear shaft of a transmission connected to an electric motor, when an electric current passes through the inside of the bearing, a spark may occur between the outer ring or the inner ring and the rolling elements, and the surfaces of the outer ring, the inner ring, and the rolling elements may become locally high in temperature and melt, resulting in electric corrosion (a phenomenon in which irregularities occur on the surface).

[0003] To prevent this electric corrosion, a rolling bearing with insulation in which the outer diameter surface of the outer ring of the rolling bearing is covered with an insulating film is used (for example, Patent Document 1).

[0004] The rolling bearing with insulation of Patent Document 1 includes an outer ring, an inner ring disposed radially inside the outer ring, a plurality of balls incorporated between the outer ring and the inner ring, and an insulating film provided on the outer ring. The insulating film has a cylindrical portion that covers the outer diameter surface of the outer ring, a one-side flange portion that extends radially inward from one axial end of the cylindrical portion and covers the width surface on one axial side of the outer ring, and a other-side flange portion that extends radially inward from the other axial end of the cylindrical portion and covers the width surface on the other axial side of the outer ring.

[0005] This insulating film is formed of a thermoplastic resin and is fixed to the surface of the outer ring by insert molding. That is, the outer ring is inserted into the inside of an injection mold, and in that state, a thermoplastic resin (for example, PPS resin) is injected into the mold to form an insulating film on the surface of the outer ring. This insert molding of the insulating film on the outer ring is performed in the state of the outer ring alone, that is, before the assembly of the rolling bearing (before incorporating a plurality of balls between the outer ring and the inner ring).

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Patent No. 3068311 [Overview of the project] [Problems that the invention aims to solve]

[0007] The insulating coating described in Patent Document 1 is formed by insert molding, which results in high manufacturing costs. Furthermore, during insert molding, there is a risk of the outer ring raceway surface being damaged by contact with the mold or of foreign matter adhering to the outer ring raceway surface, making quality control difficult.

[0008] Incidentally, in the assembly of rolling bearings, when fitting multiple balls between the outer and inner rings, a ball-cracking operation is sometimes performed when fitting the last ball. The ball-cracking operation involves positioning the inner ring eccentrically with respect to the center of the outer ring, and then fitting multiple balls into the crescent-shaped gap formed between the outer and inner rings. This operation involves forcefully pushing the last ball in while elastically deforming the outer and inner rings in the radial direction. This operation is performed with the outer ring placed in a jig or with the outer diameter surface of the outer ring firmly chucked.

[0009] Here, when the above-mentioned chucking operation is performed on an insulated rolling bearing using an outer ring with an insulating coating formed on its width surface and outer diameter surface by insert molding, there is a risk that the insulating coating on the outer ring may deform or break. Specifically, when the chucking operation is performed with the outer ring placed in a jig, the insulating coating is interposed between the outer ring and the jig, and a strong load is applied to the insulating coating by the chucking operation. Also, when the chucking operation is performed with the outer diameter surface of the outer ring chucked, the chucking is performed through the insulating coating formed on the outer diameter surface, and a strong load is applied to the insulating coating by the chucking, as well as by the chucking operation. In either case, a strong load is applied to the insulating coating during the chucking operation, so there is a risk that the insulating coating may deform or break.

[0010] The problem this invention aims to solve is to provide an insulated rolling bearing that is easy to ensure the quality of and is low-cost. [Means for solving the problem]

[0011] To solve the above problems, this invention provides an insulated rolling bearing with the following configuration. [Configuration 1] Outer ring and, An inner ring positioned radially inward of the outer ring, A plurality of rolling elements are incorporated between the outer ring and the inner ring, In an insulating rolling bearing having an insulating cover member having a cylindrical portion that covers the outer diameter surface of the outer ring, a flange portion that extends radially inward from one axial end of the cylindrical portion and covers the width surface on one axial side of the outer ring, and a flange portion that extends radially inward from the other axial end of the cylindrical portion and covers the width surface on the other axial side of the outer ring, The cylindrical portion, the flange portion on one side, and the flange portion on the other side are integrally formed from rubber material. An insulating rolling bearing characterized in that the insulating cover member has a slit formed on one side that extends radially outward from the radially inner end of the flange on one side, and further extends axially from one end of the cylindrical portion to the other axial side via the radially outer end of the flange on one side.

[0012] By adopting this configuration, the insulating rolling bearing can insulate the outer ring and prevent galvanic corrosion by covering the outer diameter surface of the outer ring and the width surfaces on one axial side and the other axial side with an insulating cover member made of rubber material. Furthermore, since the insulating cover member is made of rubber material, instead of forming an insulating film on the surface of the outer ring by insert molding, the insulating cover member can be formed separately from the outer ring first, and then attached to the outer ring by elastically deforming the insulating cover member. As a result, this method is less expensive than insert molding an insulating film, and there is no risk of scratches or foreign matter adhesion associated with insert molding, making it easier to ensure the quality of the rolling bearing.

[0013] Here, if the insulating cover member having a pair of flanges on both sides in the axial direction is made of a resin material that does not have rubber elasticity, such as PPS resin, the insulating cover member cannot be flexibly deformed and cannot be attached to the outer ring. In order to attach an insulating cover member made of a material that does not have rubber elasticity to the outer ring, it is necessary to divide the insulating cover member into two or more parts, such as in the axial direction. In contrast, the insulating rolling bearing of the above configuration 1 can be attached to the outer ring while the insulating cover member made of rubber material is elastically deformed, so it is not necessary to make the insulating cover member into two or more parts, and it can be made into a single part, resulting in low cost. Also, if there are two or more insulating cover members, there is a risk that the raceway ring will be exposed between them, and there is a concern that the bearing will conduct electricity due to contact between this exposed surface and the housing. If the insulating cover member is a single part as in this configuration, this concern is not necessary.

[0014] Furthermore, the insulating cover member can be significantly deformed by opening the slit in the flange on one side, allowing it to be easily attached to the outer ring.

[0015] [Configuration 2] The insulating rolling bearing according to Configuration 1, wherein the insulating cover member has a slit on the other side that extends radially outward from the radially inner end of the flange on the other side, and further extends axially in one direction from the other axial end of the cylindrical portion via the radially outer end of the flange on the other side.

[0016] By adopting this configuration, the insulating cover member can be deformed more significantly by opening the slits in the flange on one side and the slits in the flange on the other side, making it easier to attach to the outer ring.

[0017] [Configuration 3] The insulating rolling bearing according to configuration 2, wherein the insulating cover member is inverted, and the slits on one side and the slits on the other side are arranged alternately in the circumferential direction so that the configuration is the same as before inversion when the slit on one side after inversion is made to correspond with the slit on the other side before inversion.

[0018] When this configuration is adopted, when attaching the insulating cover member to the outer ring, there is no need to pay attention to the direction, so the assembly workability is excellent.

[0019] [Configuration 4] The insulating rolling bearing according to any one of Configurations 1 to 3, wherein the insulating cover member is detachable from the outer ring.

[0020] When this configuration is adopted, when disposing of this insulating rolling bearing, the insulating cover member can be removed from the outer ring and disposed of in a separated state from the rolling bearing. Also, in some cases, recycling of the insulating cover member is possible.

[0021] [Configuration 5] The outer diameter surface of the outer ring is a cylindrical surface without irregularities, The width surface on one side in the axial direction and the width surface on the other side in the axial direction of the outer ring are flat surfaces without irregularities, respectively, The cylindrical portion is in close contact with the outer diameter surface of the outer ring due to the elastic restoring force in the radial direction, The insulating rolling bearing according to any one of Configurations 1 to 4, wherein the one-side flange portion and the other-side flange portion are in close contact with the width surface on one side in the axial direction and the width surface on the other side in the axial direction of the outer ring, respectively, due to the elastic restoring force in the axial direction.

[0022] When this configuration is adopted, the cylindrical portion of the insulating cover member is in close contact with the outer diameter surface of the outer ring due to the elastic restoring force of the rubber material, and further, the one-side flange portion and the other-side flange portion of the insulating cover member are in close contact with the width surface on one side in the axial direction and the width surface on the other side in the axial direction of the outer ring, respectively, due to the elastic restoring force of the rubber material. Therefore, it is possible to prevent the insulating cover member from shifting with respect to the outer ring.

[0023] [Configuration 6] The insulating rolling bearing according to any one of Configurations 1 to 5, wherein the thickness of the cylindrical portion is 0.3 mm or more.

[0024] When this configuration is adopted, a sufficient insulating effect can be obtained.

[0025] Furthermore, this invention also provides the following method as a method for manufacturing the above-mentioned insulated rolling bearing. [Composition 7] Outer ring and, An inner ring positioned radially inward of the outer ring, A plurality of rolling elements are incorporated between the outer ring and the inner ring, The insulating cover member has a cylindrical portion that covers the outer diameter surface of the outer ring, a flange portion that extends radially inward from one axial end of the cylindrical portion and covers the width surface on one axial side of the outer ring, and a flange portion that extends radially inward from the other axial end of the cylindrical portion and covers the width surface on the other axial side of the outer ring. A method for manufacturing an insulated rolling bearing, wherein the cylindrical portion, the flange portion on one side, and the flange portion on the other side are integrally formed from rubber material, The insulating cover manufacturing process for manufacturing the insulating cover member, After the insulating cover manufacturing process, the insulating cover member is turned inside out in a cover inversion step so that the inner diameter surface of the cylindrical portion faces radially outward, and the axial inner surfaces of the flange on one side and the flange on the other side each face axially outward. A method for manufacturing an insulated rolling bearing, comprising: a cover mounting step, after the cover inversion step, pressing the axial inner surface of the flange on the other side that has been inverted against the width surface on the other side in the axial direction, and returning the inverted insulating cover member to its state before inversion, thereby aligning the inner diameter surface of the cylindrical portion with the outer diameter surface of the outer ring, and further aligning the axial inner surface of the flange on one side with the width surface on the one side in the axial direction, thereby attaching the insulating cover member to the outer ring.

[0026] By employing this manufacturing method, the insulating cover member is attached to the outer ring by pressing the pre-inverted insulating cover member against the outer ring and then returning it to its original position, making the attachment of the insulating cover member easy. Furthermore, since the process of inverting the insulating cover member and the process of assembling the rolling bearing can be performed in parallel, the lead time for manufacturing the insulated rolling bearing can be shortened.

[0027] [Structure 8] The rolling bearing assembly process further includes a step of incorporating the plurality of rolling elements between the outer ring and the inner ring, The method for manufacturing an insulated rolling bearing according to configuration 7, wherein the cover mounting step is performed after the rolling bearing assembly step.

[0028] By adopting this manufacturing method, multiple rolling elements are assembled between the outer and inner rings, and then the insulating cover member is attached to the outer ring. Therefore, there is no risk of the insulating cover member deforming or being damaged. In other words, if the insulating cover member is attached to the outer ring first, and then multiple rolling elements are assembled between the outer and inner rings, when the work of assembling the multiple rolling elements between the outer and inner rings (for example, a hammering operation) is performed, a strong force is applied to the insulating cover member of the outer ring, which may cause the insulating cover member to deform or be damaged. However, if the multiple rolling elements are assembled between the outer and inner rings first, and then the insulating cover member is attached to the outer ring, the work of assembling the multiple rolling elements between the outer and inner rings can be performed without the insulating cover member on the outer ring, so there is no risk of the insulating cover member deforming or being damaged.

[0029] Furthermore, this invention also provides the following as insulating cover members used in the above-mentioned insulated rolling bearing. [Composition 9] An insulating cover member for a rolling bearing having a cylindrical portion that covers the outer diameter surface of the outer ring of the rolling bearing, a flange portion that extends radially inward from one axial end of the cylindrical portion and covers the width surface on one axial side of the outer ring, and a flange portion that extends radially inward from the other axial end of the cylindrical portion and covers the width surface on the other axial side of the outer ring, An insulating cover member for a rolling bearing, characterized in that the cylindrical portion, the flange portion on one side, and the flange portion on the other side are integrally formed from a rubber material. [Effects of the Invention]

[0030] In this invention, since the insulating cover member of the insulated rolling bearing is made of rubber, instead of forming an insulating film on the surface of the outer ring by insert molding, the insulating cover member can be formed separately from the outer ring, and then attached to the outer ring by elastically deforming the insulating cover member. Therefore, this method is less expensive than insert molding the insulating film, and the risk of scratches and foreign matter adhesion associated with insert molding is eliminated, making it easier to ensure the quality of the rolling bearing. [Brief explanation of the drawing]

[0031] [Figure 1] Partial cross-sectional view of the rolling bearing of the embodiment, viewed from the axial direction. [Figure 2] Cross-sectional view along line II-II in Figure 1 [Figure 3] Figure 1 shows the insulating cover member, viewed from the axial direction as a standalone component before being attached to the rolling bearing. [Figure 4] Perspective view of the insulating cover member in Figure 3. [Figure 5] (a) is a diagram showing the state in which the axial inner surface of the flange on the other side of the inverted insulating cover member is pressed against the width surface on the other side of the outer ring in the axial direction. (b) is a diagram showing the operation of maintaining the state in (a) and returning the insulating cover member to its state before inverting, while aligning the inner diameter surface of the cylindrical part of the insulating cover member with the outer diameter surface of the outer ring. (c) is a diagram showing the state after the operation of aligning the inner diameter surface of the cylindrical part of the insulating cover member with the outer diameter surface of the outer ring in (b) has progressed. (d) is a diagram showing the state in which, from the state in (c), the axial inner surface of the flange on one side of the insulating cover member is further aligned with the width surface on one side of the axial direction of the outer ring, and the insulating cover member is attached to the outer ring. [Figure 6] A modified example of an insulating cover member, in which one slit is formed on one side and one slit on the other side, is shown in correspondence with Figure 3. [Figure 7] Figure 6 shows the insulating cover member, corresponding to Figure 4. [Modes for carrying out the invention]

[0032] Figures 1 and 2 show an insulated rolling bearing according to an embodiment of the present invention. This insulated rolling bearing comprises an outer ring 1, an inner ring 2 positioned radially inward of the outer ring 1, a plurality of rolling elements 3 incorporated between the outer ring 1 and the inner ring 2, a cage 4, and an insulating cover member 5. In this case, the rolling elements 3 are balls. This rolling bearing is a deep groove ball bearing.

[0033] Here, the direction along the bearing's central axis is called the axial direction, the direction perpendicular to the bearing's central axis is called the radial direction, and the direction along the circumference around the bearing's central axis is called the circumferential direction. The axial inner side refers to the side closer to the rolling element, the axial outer side refers to the side further away from the rolling element, the radial outer side refers to the side further away from the bearing center, and the radial inner side refers to the side closer to the bearing center.

[0034] As shown in Figure 2, the outer diameter surface 6 of the outer ring 1 is a cylindrical surface with a constant outer diameter. The outer diameter surface 6 of the outer ring 1 is not machined with grooves and is smooth. At one end of the outer ring 1 in the axial direction (left side in the figure) and the other end in the axial direction (right side in the figure), a width surface 7a on the axial side and a width surface 7b on the other end in the axial direction are formed, respectively. The width surface 7a on the axial side and the width surface 7b on the other end in the axial direction are both planes perpendicular to the axial direction. The width surface 7a on the axial side and the width surface 7b on the other end in the axial direction are not machined with grooves and are both smooth, flat surfaces. An outer ring raceway groove 8 is formed on the inner circumference of the outer ring 1 on which the balls 3 roll. The outer ring raceway groove 8 is an arc groove with a concave arc cross-section that is symmetrical in the axial direction along the surface of the balls 3, and is formed extending circumferentially at the axial center of the inner circumference surface of the outer ring 1.

[0035] Inner ring width surfaces 9 are formed on both axial sides of the inner ring 2. The inner ring width surfaces 9 are planes perpendicular to the axial direction. An inner ring raceway groove 10 is formed on the outer circumference of the inner ring 2 on which the balls 3 roll. The inner ring raceway groove 10 is an arc groove with a concave arc cross-section that is axially symmetrical along the surface of the balls 3, and is formed extending circumferentially at the axial center of the outer circumference of the inner ring 2.

[0036] The outer ring 1, inner ring 2, and ball 3 are all made of metal (for example, high- and medium-carbon alloy steel, carburized steel, bearing steel, etc.).

[0037] The retainer 4 is a crown-shaped retainer formed of an annular portion 11 and claw portions 12 that protrude axially from the annular portion 11. Between adjacent claw portions 12 in the circumferential direction, hemispherical pockets 13 for accommodating the balls 3 are formed. The retainer 4 holds the balls 3 at regular intervals in the circumferential direction. The retainer 4 is made of resin.

[0038] The insulating cover member 5 has a cylindrical portion 14, a flange portion 15a on one side, and a flange portion 15b on the other side. The cylindrical portion 14, the flange portion 15a on one side, and the flange portion 15b on the other side that constitute the insulating cover member 5 are integrally formed from an insulating rubber material. The insulating cover member 5 is formed in an annular shape that extends circumferentially and has a U-shaped cross-section that opens radially inward. Any rubber material that has rubber elasticity and insulating properties can be used to form the insulating cover member 5. For example, synthetic rubbers such as silicone rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, nitrile rubber, acrylic rubber, and fluororubber can be used, as well as natural rubber. Elastomers may also be used as the rubber material.

[0039] The cylindrical portion 14 covers the outer diameter surface 6 of the outer ring 1. The inner diameter surface 16 of the cylindrical portion 14 is a cylindrical surface with a constant inner diameter. The outer diameter surface 17 of the cylindrical portion 14 is a cylindrical surface with a constant outer diameter. One flange portion 15a extends radially inward from one axial end of the cylindrical portion 14 (left end in the figure) along the width surface 7a on one axial side (left side in the figure) of the outer ring 1. Here, one flange portion 15a extends to the radial inner end of the width surface 7a on one side, covering the entire width surface 7a on one axial side (left side in the figure) of the outer ring 1. Similarly, the other flange portion 15b extends radially inward from the other axial end of the cylindrical portion 14 (right end in the figure) along the width surface 7b on the other axial side (right side in the figure) of the outer ring 1. Here, the flange portion 15b on the other side extends to the radial inner end of the width surface 7b on the other side, covering the entire width surface 7b on the axial opposite side (right side in the figure) of the outer ring 1. The connection between the cylindrical portion 14 and the flange portion 15a on one side is made of a rounded chamfer shape that smoothly connects to the cylindrical portion 14, and the connection between the cylindrical portion 14 and the flange portion 15b on the other side is also made of a rounded chamfer shape that smoothly connects to the cylindrical portion 14.

[0040] The inner diameter of the cylindrical portion 14 of the insulating cover member 5 is set to be smaller than the outer diameter of the outer ring 1 when the insulating cover member 5 is not attached to the outer ring 1 (when the insulating cover member 5 is not elastically deformed). The cylindrical portion 14 is stretched radially and adheres tightly to the outer diameter surface 6 of the outer ring 1 due to its radial elastic restoring force. In addition, one flange portion 15a and the other flange portion 15b are provided facing each other in the axial direction. The distance between the opposing surfaces of one flange portion 15a and the other flange portion 15b is set to be smaller than the axial width length of the outer ring 1 when the insulating cover member 5 is not attached to the outer ring 1 (when the insulating cover member 5 is not elastically deformed). The one flange portion 15a and the other flange portion 15b adhere tightly to the width surface 7a on one axial side and the width surface 7b on the other axial side, respectively, when the cylindrical portion 14 is stretched in the axial direction and its axial elastic restoring force. This insulating cover member 5 can be attached to the outer ring 1 by elastic deformation, and can also be removed from the outer ring 1. In other words, the insulating cover member 5 is detachable from the outer ring 1.

[0041] As shown in Figures 2 and 4, the insulating cover member 5 has a slit 18a on one side and a slit 18b on the other side. As shown in Figure 2, the slit 18a on one side extends radially outward from the radial inner end of the flange portion 15a on one side, and further extends from one axial end (left end in the figure) to the other axial side (right side in the figure) of the cylindrical portion 14 via the radial outer end of the flange portion 15a on one side. The length of the portion of the slit 18a on one side that is formed in the cylindrical portion 14 (the length from the axial outer surface of the flange portion 15a on one side to the end of the portion extending to the other axial side (right side in the figure)) is set to be 30-70% of the axial length of the insulating cover member 5 (the axial length from the axial outer surface of the flange portion 15a on one side to the axial outer surface of the flange portion 15b on the other side). The slit 18a on one side penetrates the insulating cover member 5 in the thickness direction. The slit 18b on the other side is identical in shape and dimensions to the slit 18a on the other side. For the slit 18b on the other side, a designation is given by replacing the letter 'a' at the end of the slit 18a on the other side with 'b', and the explanation is omitted.

[0042] As shown in Figures 3 and 4, multiple slits 18a (four in the figures) are arranged on one side, and the same number of slits 18b (four in the figures) are arranged on the other side as on the one side. The slits 18a on one side and the slits 18b on the other side are arranged alternately in the circumferential direction. The circumferential distance between adjacent slits 18a on one side and slits 18b on the other side is always equal. In other words, when the insulating cover member 5 is inverted in the axial direction, and the circumferential position of the slits 18a on one side after inversion corresponds to the circumferential position of the slits 18b on the other side before inversion, the insulating cover member 5 after inversion has the same configuration as the insulating cover member 5 before inversion.

[0043] As a modified example, the insulating cover member 5 can also have one slit 18a on one side and one slit 18b on the other side, as shown in Figures 6 and 7. Here, the slit 18a on one side is located 180° opposite to the slit 18b on the other side in the circumferential direction. Although not shown, it is also possible to omit the slit 18b on the other side and form only one or more slits 18a on one side.

[0044] Currently, the system voltage of EVs is mainly around 400V, but it is expected that voltages will increase in the future, with around 1000V becoming the mainstream. It is thought that 100V, which is about 1 / 10 of the system voltage, will be applied to the rolling bearing. The inventors of this application have found that in order to prevent the occurrence of electrolytic corrosion due to this voltage, a creepage distance of 0.3 mm or more should be ensured between the rolling bearing and the housing on which the rolling bearing is mounted. Therefore, when the above-mentioned rolling bearing is used as the bearing that supports the electric motor for driving an EV, in order to ensure the creepage distance between the outer ring 1 and the housing, the thickness t of the cylindrical portion 14 is set to 0.3 mm or more (preferably 0.5 mm to 1.5 mm, more preferably 0.9 mm to 1.1 mm), as shown in Figure 2. Furthermore, the thickness of each flange portion 15a on one side and flange portion 15b on the other side is set to 0.3 mm or more (preferably 0.5 mm to 1.5 mm, more preferably 0.9 mm to 1.1 mm).

[0045] An example of a manufacturing method for the insulated rolling bearing described above will be explained. First, the insulating cover member 5 shown in Figures 3 and 4 is manufactured as a separate component from the outer ring 1 (insulating cover manufacturing process). The insulating cover member 5 is manufactured by vulcanization molding of rubber material using a mold.

[0046] Next, a cover inversion process is performed in which the insulating cover member 5 shown in Figures 3 and 4 is elastically deformed and turned inside out. Specifically, the insulating cover member 5 shown in Figures 3 and 4 is in the state it was in when removed from the mold (not turned inside out). This non-turned insulating cover member 5 is elastically deformed, and the outer diameter side and inner diameter side of the insulating cover member 5 are turned inside out. As a result, the inner diameter surface 16 of the cylindrical portion 14 of the insulating cover member 5 shown in Figure 4 faces radially outward, and the axial inner surfaces 19a and 19b of the flange portion 15a on one side and the flange portion 15b on the other side, also shown in Figure 4, face axially outward (turned inside out).

[0047] Before turning the insulating cover member 5 inside out, one flange portion 15a and the other flange portion 15b are located radially inward of the cylindrical portion 14. When turning the insulating cover member 5 inside out, it is necessary to temporarily position one flange portion 15a and the other flange portion 15b radially outward of the cylindrical portion 14, and at this time, the insulating cover member 5 needs to be significantly deformed.

[0048] When the slit 18a on one side of this insulating cover member 5 opens, the flange portion 15a on one side expands circumferentially, making it easy to deform the flange portion 15a and the cylindrical portion 14 on one side. Similarly, when the slit 18b on the other side opens, the flange portion 15b on the other side expands circumferentially, making it easy to deform the flange portion 15b and the cylindrical portion 14 on the other side. Therefore, this insulating cover member 5 can be easily turned inside out.

[0049] In addition to the aforementioned insulating cover manufacturing process and cover inversion process, a rolling bearing assembly process is carried out. In this process, the inner ring 2 is positioned eccentrically with respect to the center of the outer ring 1, multiple balls 3 are assembled between the outer ring 1 and the inner ring 2, and a cage 4 is attached to these balls 3 to assemble the rolling bearing (a rolling bearing in Figure 2 without the insulating cover member 5 attached). The rolling bearing assembly process can be carried out at any time before the cover attachment process described later.

[0050] Following the cover inversion process and the rolling bearing assembly process described above, the cover mounting process is performed. Specifically, as shown in Figure 5(a), the axial inner surface 19b of the flange portion 15b on the other side that has been inverted is pressed against the width surface 7b on the other side in the axial direction. Next, as shown in Figures 5(b) and 5(c), the inverted insulating cover member 5 is elastically deformed to return to its state before inversion, while the inner diameter surface 16 of the cylindrical portion 14 is aligned with the outer diameter surface 6 of the outer ring 1. Subsequently, as shown in Figure 5(d), the flange portion 15a on one side is elastically deformed so that the axial inner surface 19a is aligned with the width surface 7a on the other side in the axial direction. Through these operations, the insulating cover member 5 is attached to the outer ring 1.

[0051] In this cover mounting process, when the slit 18a on one side shown in Figure 4 opens, the flange portion 15a and cylindrical portion 14 on one side deform smoothly, and similarly, when the slit 18b on the other side shown in Figure 4 opens, the flange portion 15b and cylindrical portion 14 on the other side deform smoothly.

[0052] Here, in rolling bearings that support the rotating shaft of the electric motor used for driving electric vehicles such as battery electric vehicles (EVs) and hybrid electric vehicles (HEVs), and in rolling bearings that support the gear shaft of a transmission connected to an electric motor, there is a problem in that when electric current passes through the inside of the bearing, sparks are generated between the outer ring 1 or inner ring 2 and the rolling element 3, causing the surface of the outer ring 1, inner ring 2, or rolling element 3 to become locally hot and melt, resulting in electrolytic corrosion (a phenomenon in which irregularities appear on the surface) (see Figure 2).

[0053] To address this problem, as shown in Figure 2, this insulated rolling bearing covers the outer diameter surface 6 of the outer ring 1 and the width surfaces 7a and 7b on one axial side and the other axial side with an insulating cover member 5 made of rubber material. This blocks the current path into the inside of the rolling bearing, preventing sparks from occurring between the outer ring 1 or inner ring 2 and the rolling elements 3, and thus preventing electrolytic corrosion.

[0054] Furthermore, since the insulating cover member 5 of this insulated rolling bearing is made of rubber, instead of forming an insulating film on the surface of the outer ring 1 by insert molding, the insulating cover member 5 can be provided by first forming only the insulating cover member 5 separately from the outer ring 1, as shown in Figure 4, then turning the insulating cover member 5 inside out, and then, as shown in Figures 5(a) to (d), elastically deforming the inverted insulating cover member 5 and attaching it to the outer ring 1. This method is therefore less expensive than insert molding the insulating film, and eliminates the risk of scratches and foreign matter adhesion associated with insert molding, making it easier to ensure the quality of the rolling bearing.

[0055] Here, if the insulating cover member 5, which has a pair of flanges on both sides in the axial direction, is made of a resin material that does not have rubber elasticity, such as PPS resin, the insulating cover member 5 cannot be flexibly deformed and cannot be attached to the outer ring 1. In order to attach an insulating cover member 5 made of a material that does not have rubber elasticity to the outer ring 1, it is necessary to divide the insulating cover member 5 into two or more parts, such as in the axial direction. In contrast, as shown in Figures 5(a) to (d), this insulated rolling bearing can be attached to the outer ring 1 while the insulating cover member 5 made of rubber material is elastically deformed, so there is no need to make the insulating cover member 5 into two or more parts, and it can be made into a single part, resulting in low cost. Also, if there are two or more insulating cover members 5, there is a risk that the outer ring will be exposed between them, and there is a concern that the bearing will conduct electricity due to contact between this exposed surface and the housing. If it is a single part like this insulating cover member 5, there is no need to worry about this.

[0056] Furthermore, as shown in Figure 5(a), this insulated rolling bearing allows the insulating cover member 5, which is made of rubber, to be flexibly deformed. Therefore, the process of attaching the insulating cover member 5 to the outer ring 1 can be performed after the rolling bearing has been assembled (after the multiple rolling elements 3 have been assembled between the outer ring 1 and the inner ring 2). In the rolling bearing without the insulating cover member 5 attached to the outer ring 1, a general outer ring without an insulating coating can be used as the outer ring 1, and the same materials as those used in general rolling bearings can be used for other components. As a result, the assembly line for general rolling bearings can be used as is, and equipment costs can be reduced.

[0057] Furthermore, in this insulated rolling bearing, when the slits 18a on one side and 18b on the other side shown in Figure 4 open, the flanges 15a on one side and 15b on the other side expand in the circumferential direction, allowing the insulating cover member 5 to deform more significantly, making it easier to turn inside out. It can also be easily attached to the outer ring 1.

[0058] Furthermore, as shown in Figures 2 and 4, this insulated rolling bearing has slits 18a on one side and slits 18b on the other side arranged alternately in the circumferential direction. Therefore, when the insulating cover member 5 is reversed and the slit 18a on one side after reversal is made to correspond to the slit 18b on the other side before reversal, the configuration remains the same as before reversal. As a result, there is no need to worry about the orientation when attaching the insulating cover member 5 to the outer ring 1, resulting in excellent assembly workability.

[0059] Furthermore, as shown in Figure 2, the insulating cover member 5 of this insulated rolling bearing is detachable from the outer ring 1. Therefore, when disposing of the insulated rolling bearing, the insulating cover member 5 can be removed from the outer ring 1 and disposed of separately from the rolling bearing. In some cases, the insulating cover member 5 can also be recycled.

[0060] Furthermore, in this insulated rolling bearing, the cylindrical portion 14 of the insulating cover member 5 adheres tightly to the outer diameter surface 6 of the outer ring 1 due to the elastic restoring force of the rubber material, and the flange portion 15a on one side and the flange portion 15b on the other side of the insulating cover member 5 adhere tightly to the width surface 7a on one axial side and the width surface 7b on the other axial side of the outer ring 1, respectively, due to the elastic restoring force of the rubber material, thus preventing the insulating cover member 5 from sliding relative to the outer ring.

[0061] Furthermore, this insulated rolling bearing has a thickness t of 0.3 mm or more for the cylindrical portion 14 of the insulating cover member 5, ensuring sufficient insulation.

[0062] As shown in Figures 5(a) to (d), this insulated rolling bearing is attached to the outer ring 1 by pressing the inverted insulating cover member 5 against the outer ring 1 and then returning it to its original position. In other words, the insulating cover member 5 can be attached to the outer ring 1 simply by turning it right side out again, making the attachment of the insulating cover member 5 to the outer ring 1 easy. Furthermore, the process of turning the insulating cover member 5 inside out and the process of assembling the rolling bearing can be performed in parallel, thus shortening the lead time for manufacturing the insulated rolling bearing.

[0063] Furthermore, by employing this method of manufacturing insulated rolling bearings, multiple rolling elements 3 are assembled between the outer ring 1 and the inner ring 2 as shown in Figure 2, and then the insulating cover member 5 is attached to the outer ring 1. This eliminates the risk of deformation or damage to the insulating cover member 5. In other words, if the insulating cover member 5 is attached to the outer ring 1 first, and then multiple rolling elements 3 are assembled between the outer ring 1 and the inner ring 2, a strong force may be applied to the insulating cover member 5 of the outer ring 1 during the assembly process (for example, a fitting process), potentially causing deformation or damage to the insulating cover member 5. However, if multiple rolling elements 3 are assembled between the outer ring 1 and the inner ring 2 first, and then the insulating cover member 5 is attached to the outer ring 1, the assembly process can be performed without the insulating cover member 5 on the outer ring 1, thus eliminating the risk of deformation or damage to the insulating cover member 5.

[0064] In the embodiments described above, ball bearings in which the rolling elements 3 are balls have been explained, but this invention can also be applied to roller bearings in which the rolling elements 3 are rollers (for example, cylindrical roller bearings).

[0065] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0066] 1 Outer ring 2 Inner ring 3. Rolling element (ball) 5. Insulating cover component 6. Outer diameter surface of the outer ring 7a, 7b Width surface of the outer ring 14 Cylinder part 15a, 15b Tsuba 16 Inner diameter surface of the cylindrical section 18a, 18b Slit 19a, 19b Axial inner surface of the flange t Thickness of the cylindrical part

Claims

1. Outer ring (1) and, An inner ring (2) is positioned radially inward of the outer ring (1), A plurality of rolling elements (3) are incorporated between the outer ring (1) and the inner ring (2), In an insulating rolling bearing having an insulating cover member (5) having a cylindrical portion (14) that covers the outer diameter surface (6) of the outer ring (1), a flange portion (15a) that extends radially inward from one axial end of the cylindrical portion (14) and covers the width surface (7a) on one axial side of the outer ring (1), and a flange portion (15b) that extends radially inward from the other axial end of the cylindrical portion (14) and covers the width surface (7b) on the other axial side of the outer ring (1), The cylindrical portion (14), the flange portion on one side (15a), and the flange portion on the other side (15b) are integrally formed from rubber material. An insulated rolling bearing characterized in that the insulating cover member (5) has a slit (18a) formed on one side that extends radially outward from the radially inner end of the flange portion (15a) on one side, and further extends axially from one end of the cylindrical portion (14) to the other axial side via the radially outer end of the flange portion (15a) on one side.

2. The insulating rolling bearing according to claim 1, wherein the insulating cover member (5) has a slit (18b) on the other side that extends radially outward from the radially inner end of the flange (15b) on the other side, and further extends axially to one side from the other axial end of the cylindrical portion (14) via the radially outer end of the flange (15b) on the other side.

3. The insulating rolling bearing according to claim 2, wherein the insulating cover member (5) is inverted, and the slit (18a) on one side after inversion corresponds to the slit (18b) on the other side before inversion, and the slit (18a) on one side and the slit (18b) on the other side are arranged alternately in the circumferential direction so that the configuration is the same as before inversion.

4. The insulating rolling bearing according to any one of claims 1 to 3, wherein the insulating cover member (5) is detachable from the outer ring (1).

5. The outer diameter surface (6) of the outer ring (1) is a cylindrical surface without irregularities. The width surface (7a) on one axial side and the width surface (7b) on the other axial side of the outer ring (1) are both flat surfaces without irregularities. The cylindrical portion (14) is in close contact with the outer diameter surface (6) of the outer ring (1) due to the radial elastic restoring force. An insulated rolling bearing according to any one of claims 1 to 3, wherein the flange portion on one side (15a) and the flange portion on the other side (15b) are in close contact with the width surface (7a) on one side in the axial direction and the width surface (7b) on the other side in the axial direction, respectively, due to an axial elastic restoring force.

6. The insulating rolling bearing according to any one of claims 1 to 3, wherein the thickness (t) of the cylindrical portion (14) is 0.3 mm or more.

7. Outer ring (1) and, An inner ring (2) is positioned radially inward of the outer ring (1), A plurality of rolling elements (3) are incorporated between the outer ring (1) and the inner ring (2), The insulating cover member (5) has a cylindrical portion (14) that covers the outer diameter surface (6) of the outer ring (1), a flange portion (15a) that extends radially inward from one axial end of the cylindrical portion (14) and covers the width surface (7a) on one axial side of the outer ring (1), and a flange portion (15b) that extends radially inward from the other axial end of the cylindrical portion (14) and covers the width surface (7b) on the other axial side of the outer ring (1), A method for manufacturing an insulated rolling bearing, wherein the cylindrical portion (14), the flange portion on one side (15a), and the flange portion on the other side (15b) are integrally formed from rubber material, An insulating cover manufacturing process for manufacturing the insulating cover member (5), After the insulating cover manufacturing process, the insulating cover member (5) is turned inside out in a cover inversion step, such that the inner diameter surface (16) of the cylindrical portion (14) faces radially outward, and the axial inner surfaces (19a, 19b) of the flange portion (15a) on one side and the flange portion (15b) on the other side each face axially outward. A method for manufacturing an insulated rolling bearing, comprising: a cover mounting step, after the cover inversion step, pressing the axial inner surface (19b) of the inverted flange (15b) on the other side against the width surface (7b) on the other side in the axial direction, and returning the inverted insulating cover member (5) to its state before inversion, thereby aligning the inner diameter surface (16) of the cylindrical portion (14) with the outer diameter surface (6) of the outer ring (1), and further aligning the axial inner surface (19a) of the flange (15a) on one side with the width surface (7a) on the one side in the axial direction, thereby attaching the insulating cover member (5) to the outer ring (1).

8. The rolling bearing assembly process further includes a step of incorporating the plurality of rolling elements (3) between the outer ring (1) and the inner ring (2), The method for manufacturing an insulated rolling bearing according to claim 7, wherein the cover mounting step is performed after the rolling bearing assembly step.

9. An insulating cover member for a rolling bearing having a cylindrical portion (14) that covers the outer diameter surface (6) of the outer ring (1) of the rolling bearing, a flange portion (15a) that extends radially inward from one axial end of the cylindrical portion (14) and covers the width surface (7a) on one axial side of the outer ring (1), and a flange portion (15b) that extends radially inward from the other axial end of the cylindrical portion (14) and covers the width surface (7b) on the other axial side of the outer ring (1), An insulating cover member for a rolling bearing, characterized in that the cylindrical portion (14), the flange portion on one side (15a), and the flange portion on the other side (15b) are integrally formed from rubber material.

Images