Insulation rolling bearing

Abstract

To provide a low-cost insulation rolling bearing capable of preventing the peeling or creep of an insulation resin layer.SOLUTION: In the face where an insulation resin layer 4 is formed, out of the outer peripheral face of an outer ring 1 and the inner peripheral face of an inner ring 2 of the insulation rolling bearing, a knurl processing part 18 is provided consisting of a plurality of V-grooves 17 arranged in parallel to each other at constant pitches, where resin to form the insulation resin layer 4 enters.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an insulating rolling bearing. [Background technology]

[0002] In rolling bearings for devices that use electricity, such as those that support the rotating shaft of the electric motor used to drive an electric vehicle, or those that support the rotating shaft of an e-Axle that combines the electric motor, inverter, and reducer used to drive an electric vehicle, sparks can occur between the outer or inner ring and the rolling elements when an electric current passes through the inside of the bearing, causing the surface of the outer or inner ring or rolling element to become locally hot and melt, which can lead to electrolytic corrosion (a phenomenon in which unevenness appears on the surface).

[0003] To prevent this electrolytic corrosion, insulating rolling bearings are used in which the outer peripheral surface of the outer ring or the inner peripheral surface of the inner ring of the rolling bearing is covered with an insulating resin layer (for example, Patent Documents 1 and 2).

[0004] The insulated rolling bearing of Patent Document 1 has an outer ring, an inner ring arranged radially inward of the outer ring, a plurality of balls assembled between the outer ring and the inner ring, an outer ring-side insulating resin layer formed continuously over the entire outer peripheral surface of the outer ring, the entire outer ring width faces on both axial sides of the outer ring, and part of the inner peripheral surface of the outer ring, and an inner ring-side insulating resin layer formed continuously over the entire inner peripheral surface of the inner ring, the entire inner ring width faces on both axial sides of the inner ring, and part of the outer peripheral surface of the inner ring.

[0005] In the above-described insulated rolling bearing, the insulating resin layer on the outer ring side is formed by insert molding. That is, the outer ring is set in a mold, the mold is closed, and resin is injection molded to form the insulating resin layer on the outer peripheral surface, outer ring width face, and inner peripheral surface of the outer ring. Similarly, the insulating resin layer on the inner ring side is also formed by insert molding.

[0006] In the insulated rolling bearing of Patent Document 2, an insulating resin layer that is continuous with the entire outer peripheral surface of the outer ring and with parts of the outer ring width surface on both axial sides of the outer ring is also formed by insert molding.

[0007] When the insulating resin layer of the outer ring is formed by injection molding, the insulating resin layer shrinks during cooling after injection molding, and the outer ring also shrinks due to temperature changes. Due to the relationship between the mold shrinkage rate of the resin forming the insulating resin layer and the linear expansion coefficient of the steel forming the outer ring, the amount of dimensional change due to molding shrinkage of the insulating resin layer is greater than the amount of dimensional change associated with a decrease in temperature of the outer ring. This causes axial misalignment between the insulating resin layer on the outer peripheral surface of the outer ring and the outer peripheral surface, as well as radial misalignment between the insulating resin layer on the outer ring width surface and the outer ring width surface, potentially resulting in peeling of the insulating resin layer from the outer ring width surface.

[0008] Furthermore, if the adhesion of the insulating resin layer to the outer ring is insufficient, the insulating resin layer may move circumferentially relative to the outer ring (creep) during operation of the insulated rolling bearing, which could cause wear or cracks in the insulating resin layer.

[0009] Therefore, to prevent the insulating resin layer from peeling off from the width face of the outer ring or creeping against the outer ring, Patent Documents 1 and 2 form two circumferentially extending rectangular cross-section grooves in the outer peripheral surface of the outer ring, and allow the resin of the insulating resin layer to fill the grooves, thereby preventing the insulating resin layer from peeling off from the outer peripheral surface of the outer ring. Similarly, Patent Document 1 forms two circumferentially extending rectangular cross-section grooves in the inner peripheral surface of the inner ring, and allows the resin of the insulating resin layer to fill the grooves.

[0010] In addition, in Patent Document 2, a rectangular cross-section groove extending in the circumferential direction is formed on the outer ring width surface, and the resin of the insulating resin layer is allowed to enter this groove, thereby preventing the insulating resin layer from peeling off from the outer ring width surface. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 05-240255 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-308735 Summary of the Invention [Problem to be solved by the invention]

[0012] In the insulated rolling bearings of Patent Documents 1 and 2, to prevent peeling of the insulating resin layer, two rectangular cross-section grooves are formed in the outer ring, and the resin of the insulating resin layer is inserted into the grooves. However, rectangular cross-section grooves are typically formed by cutting, which requires high processing costs. Therefore, there is a need for a less expensive insulated rolling bearing that has excellent adhesion of the insulating resin layer. The insulating resin layer on the inner ring of Patent Document 1 also has the same problem.

[0013] The insulated rolling bearing of Patent Document 2 improves the adhesion of the insulating resin layer to the outer ring by forming square grooves with rectangular cross sections that extend circumferentially not only on the outer peripheral surface of the outer ring but also on the outer ring width surface. However, machining the outer ring width surface in addition to the outer peripheral surface of the outer ring increases processing costs.

[0014] The problem to be solved by the present invention is to provide an insulating rolling bearing that can prevent peeling and creep of the insulating resin layer and that is low cost. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention provides an insulating rolling bearing having the following configuration. [Configuration 1] The outer ring and an inner ring disposed radially inside the outer ring; a plurality of rolling elements incorporated between the outer ring and the inner ring; an insulating rolling bearing having at least one of an outer-ring-side insulating resin layer formed continuously over the entire outer peripheral surface of the outer ring and on outer-ring width faces on both axial sides of the outer ring, and an inner-ring-side insulating resin layer formed continuously over the entire inner peripheral surface of the inner ring and on inner-ring width faces on both axial sides of the inner ring, an insulating rolling bearing, characterized in that the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring, on which the insulating resin layer is formed, are provided with a knurled portion consisting of a plurality of V-shaped grooves arranged in parallel at a constant pitch and into which resin forming the insulating resin layer fits.

[0016] With this configuration, when an insulating resin layer is formed on the outer peripheral surface of the outer ring, a knurled portion consisting of multiple V-grooves is provided on the outer peripheral surface of the outer ring, and the resin forming the insulating resin layer penetrates into these V-grooves, increasing the contact area between the insulating resin layer and the outer ring. This increases the adhesion between the insulating resin layer and the outer ring, preventing misalignment between the insulating resin layer and the outer ring due to differences between the molding shrinkage rate of the insulating resin layer after it is formed by insert molding and the shrinkage rate associated with a temperature decrease in the outer ring. This prevents the insulating resin layer from peeling off from the width face of the outer ring or creeping relative to the outer ring. Furthermore, if an axial weld line appears in the insulating resin layer, circumferential tensile forces caused by shrinkage after injection molding can cause cracks in the insulating resin layer, originating from the weld line; this can also be prevented.

[0017] Similarly, in cases where an insulating resin layer is formed on the inner peripheral surface of the inner ring, the insulating resin layer can be prevented from peeling off from the inner ring width surface or creeping relative to the inner ring.

[0018] Furthermore, the multiple V-grooves arranged in parallel at a constant pitch in the knurled portion can be formed by rolling-type knurling, which reduces the cost of processing.

[0019] [Configuration 2] The insulated rolling bearing according to configuration 1, wherein the knurled portion has a plurality of first-direction V-grooves extending obliquely with respect to the axial direction and a plurality of second-direction V-grooves extending in a direction different from the direction in which the first-direction V-grooves extend, and is a twill knurled portion in which the first-direction V-grooves and the second-direction V-grooves intersect with each other.

[0020] In this configuration, the knurled portion into which the resin forming the insulating resin layer enters is composed of a first-direction V-groove and a second-direction V-groove extending in different directions, so that when an insulating resin layer is formed on the outer peripheral surface of the outer ring, misalignment in both the axial direction and the circumferential direction between the insulating resin layer and the outer ring can be effectively prevented. Similarly, when an insulating resin layer is formed on the inner peripheral surface of the inner ring, misalignment in both the axial direction and the circumferential direction between the insulating resin layer and the inner ring can be effectively prevented.

[0021] [Configuration 3] 2. The insulated rolling bearing according to claim 1, wherein the knurled portion is an axially flat knurled portion consisting of a plurality of V-grooves extending in the axial direction.

[0022] In this configuration, the knurled portion into which the resin forming the insulating resin layer enters is composed of multiple V-grooves extending in the axial direction, and because the V-grooves constituting the knurled portion extend in the axial direction, i.e., perpendicular to the circumferential direction, when an insulating resin layer is formed on the outer peripheral surface of the outer ring, circumferential misalignment between the insulating resin layer and the outer ring is reliably prevented, and creep of the insulating resin layer on the outer ring can be particularly effectively prevented. Similarly, when an insulating resin layer is formed on the inner peripheral surface of the inner ring, circumferential misalignment between the insulating resin layer and the inner ring is reliably prevented, and creep of the insulating resin layer on the inner ring can be particularly effectively prevented.

[0023] [Configuration 4] 2. The insulated rolling bearing according to claim 1, wherein the knurled portion is a circumferentially flat knurled portion consisting of a plurality of V-grooves extending in the circumferential direction.

[0024] In this configuration, the knurled portion into which the resin forming the insulating resin layer enters is composed of multiple V-grooves extending in the circumferential direction, and because the V-grooves constituting the knurled portion extend in the circumferential direction, i.e., perpendicular to the axial direction, when an insulating resin layer is formed on the outer peripheral surface of the outer ring, misalignment in the axial direction between the insulating resin layer and the outer ring is reliably prevented, and peeling of the insulating resin layer on the outer ring side from the width face of the outer ring can be particularly effectively prevented. Similarly, when an insulating resin layer is formed on the inner peripheral surface of the inner ring, misalignment in the axial direction between the insulating resin layer and the inner ring is reliably prevented, and peeling of the insulating resin layer on the inner ring side from the width face of the inner ring can be particularly effectively prevented.

[0025] [Configuration 5] 5. The insulating rolling bearing according to any one of configurations 1 to 4, wherein the knurled portion is provided over the entire outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring on which the insulating resin layer is formed.

[0026] In this manner, when an insulating resin layer is formed on the outer peripheral surface of the outer ring, the knurled portion is provided over the entire outer peripheral surface of the outer ring, increasing the overall surface area of ​​the knurled portion into which the resin forming the insulating resin layer penetrates. This increases the contact area between the insulating resin layer and the outer ring, effectively preventing misalignment between the insulating resin layer and the outer ring. Similarly, when an insulating resin layer is formed on the inner peripheral surface of the inner ring, effectively preventing misalignment between the insulating resin layer and the inner ring.

[0027] [Configuration 6] 5. An insulating rolling bearing according to any one of configurations 1 to 4, wherein the knurled portion is provided on only part of the axial direction of the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring on which the insulating resin layer is formed, and the remaining portions of these surfaces are cylindrical without being provided with the knurled portion.

[0028] In this way, when an insulating resin layer is formed on the outer peripheral surface of the outer ring, a portion of the outer peripheral surface in the axial direction is formed as a cylindrical surface, making it possible to accurately grind the outer ring raceway groove, outer ring width surface, etc. of the outer ring using that cylindrical surface as a reference. Furthermore, the boundary between the knurled portion and the cylindrical surface forms a step extending in the circumferential direction, preventing axial misalignment between the insulating resin layer and the outer ring. Similarly, when an insulating resin layer is formed on the inner peripheral surface of the inner ring, it becomes possible to accurately grind the inner ring raceway groove, inner ring width surface, etc. of the inner ring, and preventing axial misalignment between the insulating resin layer and the inner ring.

[0029] [Configuration 7] 7. The insulating rolling bearing according to any one of configurations 1 to 6, wherein the outer ring width surface and the inner ring width surface are flat surfaces without grooves.

[0030] In this way, since no grooves are provided on the outer ring width surface and the inner ring width surface, the only surfaces on which grooves are machined are the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring, which reduces the number of surfaces to be machined and reduces costs.

[0031] [Configuration 8] 8. The insulating rolling bearing according to any one of configurations 1 to 7, wherein the pitch of the V-grooves of the knurled portion is 0.628 to 1.571 mm, and the depth of the V-grooves of the knurled portion is 0.264 to 0.652 mm.

[0032] In this way, the V-groove of the knurled portion is formed in accordance with the dimensions of the knurls specified in the Japanese Industrial Standards (JIS B0951 "Knurls"), so it can be processed using a general-purpose knurling tool, which is low cost.

[0033] [Configuration 9] Between the adjacent V-grooves, a mountain portion having a triangular cross section is formed to separate the V-grooves, 9. The insulating rolling bearing according to any one of configurations 1 to 8, wherein the thickness of the insulating resin layer at the top of the ridges is 0.8 mm or more and 2.0 mm or less.

[0034] In this way, the thickness of the insulating resin layer is 0.8 mm or more, so that the resin has good fluidity during injection molding and has high insulating performance.

[0035] [Configuration 10] 10. The insulating rolling bearing according to any one of configurations 1 to 9, wherein the insulating resin layer is formed from a resin having a molding shrinkage rate of 0.2% or more.

[0036] [Configuration 11] The insulating resin layer has a thickness of 1.0×10 -5 / ℃ or more, and in the circumferential direction, it has a linear expansion coefficient of 2.0×10 -5 11. The insulating rolling bearing according to any one of aspects 1 to 10, having a linear expansion coefficient of 1 / °C or more.

[0037] [Configuration 12] 12. The insulating rolling bearing according to any one of configurations 1 to 11, wherein the insulating resin layer is formed of a resin having a dielectric breakdown strength of 1 kV / mm or more.

[0038] In this way, the dielectric breakdown strength of the resin forming the insulating resin layer is set to 1 kV / mm or more, and therefore the insulating performance is high. [Effects of the Invention]

[0039] The insulating rolling bearing of the present invention can prevent peeling and creep of the insulating resin layer, and is low-cost. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a partial cross-sectional view of an insulating rolling bearing according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the outer ring and its vicinity in FIG. 1. [Figure 3] 2 is a perspective view showing the outer peripheral surface of the outer ring with a portion of the insulating resin layer of FIG. 1 cut away. FIG. [Figure 4] FIG. 4 is a partial cross-sectional view of an insulating rolling bearing according to a second embodiment of the present invention. [Figure 5] FIG. 5 is an enlarged view of the vicinity of the outer ring in FIG. 4. [Figure 6] 5 is a perspective view showing the outer peripheral surface of the outer ring with a portion of the insulating resin layer of FIG. 4 cut away. [Figure 7] FIG. 4 is a partial cross-sectional view of an insulating rolling bearing according to a third embodiment of the present invention. [Figure 8] FIG. 8 is an enlarged view of the vicinity of the outer ring in FIG. 7. [Figure 9] 8 is a perspective view showing the outer peripheral surface of the outer ring with a part of the insulating resin layer of FIG. 7 cut away. [Figure 10] FIG. 10 is a partial cross-sectional view of an insulating rolling bearing according to a fourth embodiment of the present invention. [Figure 11] FIG. 11 is an enlarged view of the vicinity of the outer ring of FIG. 10. [Figure 12] 11 is a perspective view showing the outer peripheral surface of the outer ring with a portion of the insulating resin layer of FIG. 10 cut away. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0041] [First embodiment] An insulating rolling bearing according to a first embodiment of the present invention is shown in Figures 1 to 3. This insulating rolling bearing is a bearing used to support the rotating shaft of an electric motor used to drive an electric vehicle, or to support the rotating shaft of an e-Axle that integrates an electric motor, inverter, and reducer used to drive an electric vehicle.

[0042] This insulated rolling bearing has an outer ring 1, an inner ring 2 arranged radially inside the outer ring 1, a plurality of rolling elements 3 incorporated between the outer ring 1 and the inner ring 2, an insulating resin layer 4 on the outer ring side, and a cage 5. In this example, the rolling elements 3 are balls.

[0043] Here, the direction along the bearing central axis is called the axial direction, the direction perpendicular to the bearing central axis is called the radial direction, and the direction along the circumference around the bearing central axis is called the circumferential direction.

[0044] As shown in Figure 2, outer ring width faces 6 are formed on both axial sides of the outer ring 1. The outer ring width faces 6 are flat surfaces perpendicular to the axial direction. The inner circumference of the outer ring 1 is formed with an outer ring raceway groove 7 in which the rolling elements 3 roll, a cylindrical surface 8 with a constant inner diameter adjacent to the outer ring raceway groove 7, and a chamfered portion 9 connecting the cylindrical surface 8 and the outer ring width faces 6. The outer ring raceway groove 7 is an arc groove with a concave arc-shaped cross section that follows the surface of the rolling elements 3, and is formed at the axial center of the inner peripheral surface of the outer ring 1, extending circumferentially.

[0045] As shown in Figure 1, inner ring width surfaces 10 are formed on both axial sides of the inner ring 2. The inner ring width surfaces 10 are flat surfaces perpendicular to the axial direction. The outer periphery of the inner ring 2 is formed with an inner ring raceway groove 11 in which the rolling elements 3 roll, a cylindrical surface 12 with a constant outer diameter adjacent to the inner ring raceway groove 11, and a chamfered portion 13 connecting the cylindrical surface 12 and the inner ring width surface 10. The inner ring raceway groove 11 is an arc groove with a concave arc-shaped cross section that follows the surface of the rolling elements 3, and is formed at the axial center of the outer periphery of the inner ring 2, extending circumferentially.

[0046] The outer ring 1, inner ring 2, and rolling elements 3 are all formed of metal (for example, steel such as high- or medium-carbon alloy steel, carburized steel, or bearing steel).

[0047] As shown in FIG. 2 , the insulating resin layer 4 has an outer peripheral insulating portion 14 that covers the outer peripheral surface of the outer ring 1, width surface insulating portions 15 that cover the outer ring width faces 6 on both sides, and connecting portions 16 that connect the outer peripheral insulating portion 14 and the width surface insulating portion 15. The outer peripheral surface of the outer peripheral insulating portion 14 is a cylindrical surface with a constant outer diameter and covers the entire outer peripheral surface of the outer ring 1. The width surface insulating portion 15 is formed as an annular plate that extends radially inward from the radial outer end of the outer ring width face 6 to the center of the outer ring width face 6. The width surface insulating portion 15 is not formed radially inward from the center of the outer ring width face 6, and the outer ring width face 6 is exposed in the portion radially inward from the center of the outer ring width face 6. The outer periphery of the connecting portion 16 has a R-chamfered shape that smoothly connects to the outer peripheral insulating portion 14. Here, the outer peripheral insulating portion 14, connecting portions 16, and width surface insulating portions 15 are formed integrally. That is, the insulating resin layer 4 is formed continuously over the entire outer peripheral surface of the outer ring 1 and on outer ring width faces 6 on both axial sides of the outer ring 1 .

[0048] The insulating resin layer 4 is made of an insulating resin. Specifically, the insulating resin layer 4 is made of a resin with a dielectric breakdown strength of 1 kV / mm or more (measured in accordance with the International Electrotechnical Commission IEC 60243-1). Examples of resins that can be used include polyphenylene sulfide resin (PPS) and polyphthalamide resin (PPA). The insulating resin layer 4 blocks the current path to the inside of the bearing, preventing sparks from occurring between the inner surface of the outer ring raceway groove 7 and the surface of the rolling element 3, or between the inner surface of the inner ring raceway groove 11 and the surface of the rolling element 3, as shown in FIG. 1.

[0049] The resin used to form the insulating resin layer 4 contains a fiber reinforcement material. The fiber reinforcement material used is an insulating material such as glass fiber or aramid fiber. The resin has a molding shrinkage rate of 0.2% or more.

[0050] The insulating resin layer 4 is formed by insert molding. That is, the outer ring 1 is set inside a mold, and molten resin is injected into the mold, forming the insulating resin layer 4 on the surface of the outer ring 1. The mold used for insert molding has a disk gate, rather than a pin gate, as the gate through which the molten resin is injected into the mold. The disk gate is located on one axial side of the mold. The insulating resin layer 4 is formed by injecting molten resin from the disk gate on one axial side toward the other axial side. It is known that the linear expansion coefficient of an injection-molded product is anisotropic, being greater in the direction perpendicular to the injection direction than in the direction parallel to the injection direction. Therefore, the linear expansion coefficient of the insulating resin layer 4 in the circumferential direction is higher than the linear expansion coefficient in the axial direction. The insulating resin layer 4 in this embodiment of the present invention has a linear expansion coefficient of 1.0 × 10 in the axial direction. -5 / ℃ or more, and in the circumferential direction, it has a linear expansion coefficient of 2.0×10 -5 / °C or more. If the outer ring 1 and inner ring 2 are made of steel, the linear expansion coefficient of the outer ring 1 and inner ring 2 is 1.1 x 10 -5 / °C. The linear expansion coefficient is a value obtained by measurement in accordance with the international standard ISO11359-2.

[0051] The axial width dimension of the outer ring 1 (width dimension not including the insulating resin layer 4; width dimension from one of the outer ring width faces 6 on both sides to the other outer ring width face 6) is smaller than the axial width dimension of the inner ring 2 (width dimension from one of the inner ring width faces 10 on both sides to the other inner ring width face 10). The combined width dimension of the insulating resin layer 4 and the outer ring 1 is equal to the width dimension of the inner ring 2.

[0052] The entire outer peripheral surface of the outer ring 1 is provided with a knurled portion 18 consisting of a plurality of V-grooves 17 arranged in parallel at a constant pitch, and the resin that forms the insulating resin layer 4 fills each of the V-grooves 17 that make up the knurled portion 18. This knurled portion 18 has a plurality of first-direction V-grooves 17a that extend obliquely relative to the axial direction and a plurality of second-direction V-grooves 17b that extend in a direction different from the extension of the first-direction V-grooves 17a, forming a twill knurled portion 18 in which the first-direction V-grooves 17a and the second-direction V-grooves 17b intersect with each other. Both axial ends of the outer peripheral surface of the outer ring 1 are chamfered around the entire circumference.

[0053] The first-direction V grooves 17a are inclined at a predetermined inclination angle a toward one circumferential side with respect to the axial direction. The second-direction V grooves 17b are inclined at an angle (inclination angle b) equal to the inclination angle a of the first-direction V grooves 17a toward the other circumferential side with respect to the axial direction. The inclination angle a of the first-direction V grooves 17a (and the inclination angle b of the second-direction V grooves 17b) is set to 30° or 45° in accordance with the Japanese Industrial Standard (JIS B 0951 "Knurling"). That is, the inclination angle a of the first-direction V grooves 17a (and the inclination angle b of the second-direction V grooves 17b) is set to 29° or more and 31° or less (30° in the figure) or 44° or more and 46° or less.

[0054] The outer ring width surface 6 is a flat surface with no grooves machined into it. That is, of the outer peripheral surface of the outer ring 1 and the outer ring width surface 6, grooves (V grooves 17) are machined only on the outer peripheral surface of the outer ring 1, and the outer ring width surface 6 is a flat surface with no grooves machined into it.

[0055] The cage 5 is a crown-type cage formed by an annular portion 19 and claw portions (not shown) that protrude axially from the annular portion 19. Hemispherical pockets that accommodate balls are formed between adjacent claw portions in the circumferential direction. The cage 5 holds balls in each pocket, thereby holding the rolling elements 3 at regular intervals in the circumferential direction. The cage 5 is made of resin.

[0056] The pitch p of the first-direction V-grooves 17a and the second-direction V-grooves 17b that make up the knurled portion 18 is both 0.628 to 1.571 mm, and the depth h (see FIG. 2) of the first-direction V-grooves 17a and the second-direction V-grooves 17b is both 0.264 to 0.652 mm. The V-grooves 17 having this depth h are obtained by processing a knurled pattern with a cross stitch module of m0.2, m0.3, or m0.5, as specified in the Japanese Industrial Standards (JIS B0951 "Knurling"), in accordance with the same standard.

[0057] As shown in Fig. 2, between adjacent first-direction V grooves 17a, there are formed ridges 20 with a triangular cross section that separate the first-direction V grooves 17a, and between adjacent second-direction V grooves 17b, there are also formed ridges 20 with a triangular cross section that separate the second-direction V grooves 17b. As a result, as shown in Fig. 3, the portion surrounded by adjacent first-direction V grooves 17a and adjacent second-direction V grooves 17b forms a quadrangular pyramidal protrusion 21. The protrusions 21 are formed at regular intervals over the entire outer peripheral surface of the outer ring 1.

[0058] As shown in FIG. 2, insulating resin layer 4 is formed to have a thickness t of 0.8 mm or more (preferably 1.0 mm or more) and 2.0 mm or less at the top of ridge portion 20. That is, insulating resin layer 4 is formed so that the minimum thickness of insulating resin layer 4 on the outer peripheral surface of outer ring 1 is 0.8 mm or more (preferably 1.0 mm or more). In a cross section perpendicular to the direction in which first-direction V-groove 17a extends, the angle formed by the two inclined surfaces forming first-direction V-groove 17a is set to be 88° or more and 92° or less (e.g., 90°). Similarly, in a cross section perpendicular to the direction in which second-direction V-groove 17b extends, the angle formed by the two inclined surfaces forming second-direction V-groove 17b is also set to be 88° or more and 92° or less (e.g., 90°).

[0059] Both first-direction V-groove 17a and second-direction V-groove 17b are rolled grooves formed by a rolling-type knurling process described below, and have a continuous metal structure with a curved shape that follows V-groove 17 (see FIG. 1). The metal structure of V-groove 17 can be observed by cutting outer ring 1 and corroding the cut surface with an etching solution containing nitric acid (such as nital).

[0060] The outer ring 1 is manufactured as follows. First, a metal material is forged to form an annular outer ring blank. Next, an outer ring raceway groove 7 extending in the circumferential direction is formed by turning in the axial center of the inner peripheral surface of the outer ring blank. Thereafter, a V-groove 17 (see FIG. 1) with a knurled portion 18 (see FIG. 3) is formed in the outer peripheral surface of the outer ring blank by rolling knurling. That is, a knurling piece having a twill-patterned unevenness on its outer periphery is pressed against the outer peripheral surface of the outer ring blank, plastically deforming the outer peripheral surface of the outer ring blank into the twill-patterned unevenness, thereby forming the V-groove 17 with a knurled portion 18 in the outer peripheral surface of the outer ring blank. The outer ring blank is then heat treated. Next, the outer ring width surface 6, outer periphery, and outer ring raceway groove 7 of the outer ring blank are each ground, and the outer ring raceway groove 7 is then superfinished to obtain the outer ring 1.

[0061] Thereafter, insulating resin layer 4 is formed by insert molding. That is, outer ring 1 that has been subjected to the above-described superfinishing process is set in a mold, and the mold is closed to injection mold resin (resin molding), thereby forming insulating resin layer 4 on the outer peripheral surface of outer ring 1 and outer ring width face 6.

[0062] In the insulated rolling bearing of this embodiment, as shown in FIG. 1 , a knurled portion 18 consisting of multiple V-grooves 17 is formed on the outer peripheral surface of the outer ring 1, and the resin forming the insulating resin layer 4 penetrates into these V-grooves 17, increasing the contact area between the insulating resin layer 4 and the outer ring 1. This increases the adhesion between the insulating resin layer 4 and the outer ring 1, preventing misalignment between the insulating resin layer 4 and the outer ring 1 due to differences between the molding shrinkage rate of the insulating resin layer 4 after it is formed by insert molding and the shrinkage rate associated with a temperature decrease in the outer ring 1. This prevents the insulating resin layer 4 from peeling off from the outer ring width face 6 or creeping against the outer ring 1.

[0063] Furthermore, if an axially extending weld line occurs in the insulating resin layer 4, the circumferential tensile force caused by shrinkage after injection molding may cause cracks to occur in the insulating resin layer 4 starting from the weld line, but this can also be prevented.

[0064] Furthermore, the plurality of V-grooves 17 arranged in parallel at a constant pitch in the knurled portion 18 can be formed by rolling-type knurling, which reduces the cost of processing.

[0065] Furthermore, in this insulating rolling bearing, the knurled portion 18 into which the resin forming the insulating resin layer 4 enters is composed of a first-direction V-groove 17a and a second-direction V-groove 17b extending in different directions, making it possible to effectively prevent misalignment in both the axial direction between the insulating resin layer 4 and the outer ring 1 and the circumferential direction between the insulating resin layer 4 and the outer ring 1.

[0066] Furthermore, as shown in Figure 3, this insulating rolling bearing has knurling 18 provided across the entire outer peripheral surface of outer ring 1, increasing the overall surface area of ​​knurling 18 into which the resin forming insulating resin layer 4 penetrates. This increases the contact area between insulating resin layer 4 and outer ring 1, effectively preventing misalignment between insulating resin layer 4 and outer ring 1.

[0067] Furthermore, as shown in FIG. 2, the outer ring 1 of this insulated rolling bearing does not have grooves on the outer ring width face 6, and the only surface on which grooves are machined is the outer peripheral surface of the outer ring 1, which means there are fewer surfaces to machine and lower costs.

[0068] Furthermore, as shown in FIG. 1, the V-groove 17 of the knurled portion 18 of this insulating rolling bearing is formed in accordance with the dimensions of the knurls specified in the Japanese Industrial Standards (JIS B 0951 "Knurls"), so that it can be processed using a general-purpose knurling tool, making it low cost.

[0069] Furthermore, as shown in FIG. 2, this insulating rolling bearing has an insulating resin layer 4 with a thickness t of 0.8 mm or more, which provides good resin fluidity during injection molding and high insulating performance.

[0070] Furthermore, this insulated rolling bearing has high insulation performance because the dielectric breakdown strength of the resin forming insulating resin layer 4 is 1 kV / mm or more. In this case, assuming that the system voltage of the electric motor or e-Axle of an electric vehicle is approximately 800 V, for example, if the dielectric breakdown strength of the resin forming insulating resin layer 4 is 1 kV / mm or more, sufficient insulation performance can be ensured by setting the thickness t of insulating resin layer 4 to 0.8 mm or more.

[0071] Furthermore, because the pair of width face insulating portions 15 of the insulating resin layer 4 sandwich the outer ring 1 from both axial sides, it is possible to reliably prevent axial movement of the insulating resin layer 4 relative to the outer ring 1. As a result, axial misalignment between the insulating resin layer 4 and the outer ring 1 can be reliably prevented.

[0072] [Second embodiment] 4 to 6 show an insulated rolling bearing according to a second embodiment of the present invention. The second embodiment differs from the first embodiment only in that the outer peripheral surface of the outer ring 1 is provided with an axial flat knurling portion 18 rather than a diagonal knurling portion 18. That is, in the first embodiment, the knurling portion 18 on the outer peripheral surface of the outer ring 1 is a diagonal knurling portion 18 in which a plurality of first-direction V-grooves 17a extending obliquely relative to the axial direction intersect with a plurality of second-direction V-grooves 17b extending in a direction different from the extension direction of the first-direction V-grooves 17a, whereas in the second embodiment, the knurling portion 18 is an axial flat knurling portion 18 made up of a plurality of axially extending V-grooves 17; otherwise, the configuration is the same. Therefore, parts corresponding to those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted.

[0073] As shown in Figures 4 and 6, the V grooves 17 of the axially aligned flat knurled portion 18 are aligned parallel to one another at a constant pitch. Both axial ends of the outer peripheral surface of the outer ring 1 are chamfered along the entire circumference. The pitch p of the V grooves 17 (see Figure 4) is 0.628 to 1.571 mm, and the depth h of the V grooves 17 (see Figure 5) is 0.264 to 0.652 mm. V grooves 17 with this depth h are obtained by machining flat knurls with a module of m0.2, m0.3, or m0.5 as specified in the Japanese Industrial Standards. Between adjacent V grooves 17, a triangular-section ridge 20 is formed to separate the V grooves 17.

[0074] 5, insulating resin layer 4 is formed to have a thickness t of 0.8 mm or more (preferably 1.0 mm or more) and 2.0 mm or less at the top of ridge portion 20. In other words, insulating resin layer 4 is formed so that the minimum thickness of insulating resin layer 4 on the outer peripheral surface of outer ring 1 is 0.8 mm or more (preferably 1.0 mm or more). The angle between the two inclined surfaces forming V-groove 17 is set to be 88° or more and 92° or less (for example, 90°).

[0075] 6, in the insulating rolling bearing of the second embodiment, knurling 18 into which the resin forming insulating resin layer 4 enters is composed of a plurality of V-grooves 17 extending in the axial direction, and because the direction in which V-grooves 17 constituting knurling 18 extend is the axial direction, i.e., a direction perpendicular to the circumferential direction, misalignment in the circumferential direction between insulating resin layer 4 and outer ring 1 is reliably prevented, and creep of insulating resin layer 4 on the outer ring side can be particularly effectively prevented. In addition, the same effects as those of the first embodiment are achieved.

[0076] [Third embodiment] 7 to 9 show an insulated rolling bearing according to a third embodiment of the present invention. The third embodiment differs from the first embodiment only in that the outer peripheral surface of the outer ring 1 is provided with a circumferential flat knurling 18 rather than a diagonal knurling 18. That is, in the first embodiment, the knurling 18 on the outer peripheral surface of the outer ring 1 is a diagonal knurling 18 in which a plurality of first-direction V-grooves 17a extending obliquely relative to the axial direction intersect with a plurality of second-direction V-grooves 17b extending in a direction different from the direction in which the first-direction V-grooves 17a extend, whereas in the third embodiment, the knurling 18 is a circumferential flat knurling 18 made up of a plurality of circumferentially extending V-grooves 17; otherwise, the configuration is the same. Therefore, parts corresponding to those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted.

[0077] As shown in Figures 7 and 9, the V grooves 17 of the circumferential flat knurling portion 18 are formed in parallel rows at a constant pitch in the circumferential direction. Both axial ends of the outer peripheral surface of the outer ring 1 are chamfered along the entire circumference. The pitch p of the V grooves 17 (see Figure 7) is 0.628 to 1.571 mm, and the depth h of the V grooves 17 (see Figure 8) is 0.264 to 0.652 mm. V grooves 17 with this depth h are obtained by machining flat knurling with a module of m0.2, m0.3, or m0.5 as specified in the Japanese Industrial Standards. Between adjacent V grooves 17, a triangular-section ridge 20 is formed to separate the V grooves 17.

[0078] 8, insulating resin layer 4 is formed to have a thickness t of 0.8 mm or more (preferably 1.0 mm or more) and 2.0 mm or less at the top of ridge portion 20. In other words, insulating resin layer 4 is formed so that the minimum thickness of insulating resin layer 4 on the outer peripheral surface of outer ring 1 is 0.8 mm or more (preferably 1.0 mm or more). The angle between the two inclined surfaces forming V-groove 17 is set to 88° or more and 92° or less (90° in the figure).

[0079] 9, in the insulating rolling bearing of the third embodiment, knurling 18 into which the resin forming insulating resin layer 4 enters is composed of a plurality of V-shaped grooves 17 extending in the circumferential direction, and because the V-shaped grooves 17 constituting knurling 18 extend in the circumferential direction, i.e., perpendicular to the axial direction, axial misalignment between insulating resin layer 4 and outer ring 1 is reliably prevented, and peeling of insulating resin layer 4 on the outer ring side from outer ring width face 6 can be particularly effectively prevented. In addition, the same effects as those of the first embodiment are achieved.

[0080] [Fourth embodiment] 10 to 12 show an insulated rolling bearing according to a fourth embodiment of the present invention. The fourth embodiment differs from the first embodiment in that knurled portion 18 is provided only on a portion of the outer peripheral surface of outer ring 1 in the axial direction, rather than on the entire outer peripheral surface of outer ring 1, and the remainder of the outer peripheral surface of outer ring 1 is a cylindrical surface 22; otherwise, the configuration is the same. Therefore, parts corresponding to those in the first embodiment are given the same reference numerals, and description thereof will be omitted.

[0081] As shown in Figures 10 and 12, the knurled portion 18 is an axially extending flat knurled portion 18 consisting of multiple V-grooves 17 extending in the axial direction. The V-grooves 17 of the axially extending flat knurled portion 18 are aligned parallel to each other at a constant pitch. Both axial ends of the outer peripheral surface of the outer ring 1 are chamfered along the entire circumference. The pitch p (see Figure 10) of the V-grooves 17 of the axially extending flat knurled portion 18 is 0.628 to 1.571 mm, and the depth h (see Figure 11) of the V-grooves 17 is 0.264 to 0.652 mm. V-grooves 17 with this depth h are obtained by machining flat knurls with a module of m0.2, m0.3, or m0.5 as specified in the Japanese Industrial Standards. As shown in Figure 12, a triangular-section ridge 20 is formed between adjacent V-grooves 17, separating them.

[0082] 11, insulating resin layer 4 is formed to have a thickness t of 0.8 mm or more (preferably 1.0 mm or more) and 2.0 mm or less at the top of ridge portion 20. In other words, insulating resin layer 4 is formed so that the minimum thickness of insulating resin layer 4 on the outer peripheral surface of outer ring 1 is 0.8 mm or more (preferably 1.0 mm or more). The angle between the two inclined surfaces forming V-groove 17 is set to 88° or more and 92° or less (90° in the figure).

[0083] As shown in FIG. 12 , the outer peripheral surface of the outer ring 1 is provided with a knurled portion 18 on only a portion in the axial direction, with the remaining portion being a cylindrical surface 22 without a knurled portion 18. That is, the outer peripheral surface of the outer ring 1 is formed with a cylindrical surface 22 on one axial side, a knurled portion 18, and a cylindrical surface 22 on the other axial side, all of which are adjacent to each other in the axial direction. A step 23 extending in the circumferential direction is formed between the knurled portion 18 and the cylindrical surface 22 on one axial side, and a step 24 extending in the circumferential direction is also formed between the knurled portion 18 and the cylindrical surface 22 on the other axial side. The step 23 and the step 24 are formed opposite each other in the axial direction, with the knurled portion 18 between them. The step 23 rises radially outward from the V-groove 17 side toward the cylindrical surface 22 side, connecting the inner surface of the V-groove 17 and the cylindrical surface 22. Similarly, the step 24 is a portion that rises radially outward from the V-groove 17 side toward the cylindrical surface 22 side, and connects the inner surface of the V-groove 17 and the cylindrical surface 22.

[0084] In the insulating rolling bearing of the fourth embodiment, a portion of the axial direction of the outer peripheral surface of the outer ring 1 is made into a cylindrical surface 22, so that grinding of the outer ring raceway groove 7 (see Figure 11), outer ring width surface 6, etc. can be carried out with high precision using the cylindrical surface 22 as a reference.

[0085] Furthermore, in the insulating rolling bearing of the fourth embodiment, steps 23 and 24 extending in the circumferential direction are formed facing each other on both axial sides of knurled portion 18, thereby reliably preventing misalignment in the axial direction between insulating resin layer 4 and outer ring 1. This is because part of the resin forming insulating resin layer 4 is sandwiched between steps 23 and 24 extending in the circumferential direction of knurled portion 18, restricting movement of insulating resin layer 4 in the axial direction on both sides. In addition, the same effects as those of the first embodiment are achieved.

[0086] Here, the outer peripheral surface of the outer ring 1 may not be formed with the cylindrical surface 22 on the other axial side, and only the knurled portion 18 and the cylindrical surface 22 on one axial side may be formed adjacent to each other in the axial direction. In this case, a step 23 extending in the circumferential direction is formed between the knurled portion 18 and the cylindrical surface 22 on one axial side. In the insulated rolling bearing of this embodiment, too, it is possible to perform grinding of the outer ring raceway groove 7 (see FIG. 11 ), outer ring width surface 6, etc. with high precision, using the cylindrical surface 22 as a reference. Furthermore, it is possible to reliably prevent misalignment of the insulating resin layer 4 and the outer ring 1 to one side in the axial direction.

[0087] In the above embodiments, the insulating resin layer 4 is formed on the outer ring 1 and the outer ring width face 6, but it may also be formed on the inner ring 2 and the inner ring width face 10. That is, the inner circumferential surface of the inner ring 2 may be provided with a knurled portion 18 into which the resin forming the insulating resin layer 4 penetrates, and the insulating resin layer 4 may be formed continuously over the entire inner circumferential surface of the inner ring 2 and the inner ring width face 10. Furthermore, the insulating resin layer 4 may be formed on the outer ring 1 and the outer ring width face 6, and at the same time, on the inner ring 2 and the inner ring width face 10. Furthermore, the knurled portion 18 in the fourth embodiment may be a twill knurl or a circumferentially flat knurl. Furthermore, in the above embodiments, a ball bearing in which the rolling elements 3 are balls has been described, but the present invention is also applicable to roller bearings in which the rolling elements 3 are rollers.

[0088] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0089] 1 outer ring 2. Inner circle 3 Rolling elements 4. Insulating resin layer 6 Outer ring width 10 Inner ring width 17 V groove 17a V-groove in the first direction 17b Second direction V groove 18 Knurled part 20 Yamabe 22 Cylindrical Surface p pitch h depth t thickness

Claims

1. The outer ring (1) and an inner ring (2) disposed radially inside the outer ring (1); a plurality of rolling elements (3) assembled between the outer ring (1) and the inner ring (2); an insulating rolling bearing having at least one insulating resin layer (4) of an outer ring-side insulating resin layer (4) formed continuously on the entire outer peripheral surface of the outer ring (1) and on outer ring width faces (6) on both axial sides of the outer ring (1), and an inner ring-side insulating resin layer (4) formed continuously on the entire inner peripheral surface of the inner ring (2) and on inner ring width faces (10) on both axial sides of the inner ring (2), an insulating rolling bearing, characterized in that the outer peripheral surface of the outer ring (1) and the inner peripheral surface of the inner ring (2) on which the insulating resin layer (4) is formed are provided with a knurled portion (18) consisting of a plurality of V-shaped grooves (17) arranged in parallel at a constant pitch into which resin forming the insulating resin layer (4) enters.

2. 2. The insulating rolling bearing according to claim 1, wherein the knurled portion (18) has a plurality of first-direction V-grooves (17 a) extending obliquely with respect to the axial direction and a plurality of second-direction V-grooves (17 b) extending in a direction different from the direction in which the first-direction V-grooves (17 a) extend, and the first-direction V-grooves (17 a) and the second-direction V-grooves (17 b) intersect with each other to form a twill knurled portion (18).

3. 2. An insulating rolling bearing according to claim 1, wherein the knurled portion (18) is an axially flat knurled portion (18) consisting of a plurality of V-grooves (17) extending in the axial direction.

4. 2. An insulating rolling bearing according to claim 1, wherein the knurled portion (18) is a circumferentially flat knurled portion (18) consisting of a plurality of V-grooves (17) extending in the circumferential direction.

5. 5. An insulating rolling bearing according to claim 1, wherein the knurled portion (18) is provided over the entire outer peripheral surface of the outer ring (1) and the entire inner peripheral surface of the inner ring (2), on which the insulating resin layer (4) is formed.

6. 5. An insulating rolling bearing according to claim 1, wherein the knurled portion (18) is provided only on a portion in the axial direction of the outer peripheral surface of the outer ring (1) and the inner peripheral surface of the inner ring (2), on which the insulating resin layer (4) is formed, and the remaining portions of the surfaces are cylindrical surfaces (22) without being provided with the knurled portion (18).

7. 5. An insulating rolling bearing according to claim 1, wherein the outer ring width surface (6) and the inner ring width surface (10) are flat surfaces without grooves.

8. 5. An insulating rolling bearing according to claim 1, wherein the pitch (p) of the V-groove (17) of the knurled portion (18) is 0.628 to 1.571 mm, and the depth (h) of the V-groove (17) of the knurled portion (18) is 0.264 to 0.652 mm.

9. Between adjacent V-grooves (17), a mountain portion (20) having a triangular cross section is formed to separate the V-grooves (17), 5. An insulating rolling bearing according to claim 1, wherein the thickness (t) of the insulating resin layer (4) at the top of the ridges (20) is 0.8 mm or more and 2.0 mm or less.

10. 5. An insulating rolling bearing according to claim 1, wherein the insulating resin layer (4) is formed from a resin having a molding shrinkage rate of 0.2% or more.

11. The insulating resin layer (4) has a thickness of 1.0×10 －５ / °C or more, and in the circumferential direction, －５ 5. An insulating rolling bearing according to claim 1, having a coefficient of linear expansion of 1 / °C or more.

12. 5. An insulating rolling bearing according to claim 1, wherein the insulating resin layer (4) is formed from a resin having a dielectric breakdown strength of 1 kV / mm or more.

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