Resin molded insulated bearing

Abstract

Provided is an insulated rolling bearing having an outer ring (1), an inner ring (2), and a plurality of rolling elements (3). The outer ring (1) is formed of: a steel outer diameter-side ring member (1a) having a cylindrical fitting surface (7) on the outer periphery; a steel inner diameter-side ring member (1b) having an outer-ring raceway groove (5) on the inner periphery; and a resin intermediate resin layer (1c) connecting the outer diameter-side ring member (1a) and the inner diameter-side ring member (1b).

Description

Resin-molded insulated bearing

[0001] The present invention relates to an insulated rolling bearing.

[0002] In a rolling bearing that supports a rotating shaft of an apparatus that uses electricity, when current flows through the inside of the bearing, sparks are generated between the outer ring or inner ring and the rolling elements, and the sparks may cause a phenomenon called electric corrosion, in which the surfaces of the outer ring, inner ring, and rolling elements are locally melted.

[0003] In order to prevent this electric corrosion, resin-molded insulated rolling bearings provided with a resin layer covering the surface of the outer ring, as disclosed in Patent Documents 1 to 3, are known. FIG. 12 shows an example of a resin-molded insulated rolling bearing. This resin-molded insulated rolling bearing comprises an outer ring 51, an inner ring 52 disposed radially inward of the outer ring 51, and a plurality of rolling elements 53 in rolling contact with an outer ring raceway groove 55 formed on the inner circumference of the outer ring 51 and an inner ring raceway groove 56 formed on the outer circumference of the inner ring 52. The outer ring 51 is constituted by a steel outer ring main body 51a and a resin layer 51b provided along the surface of the outer ring main body 51a. The resin layer 51b is formed by placing the outer ring main body 51a in a mold, closing the mold, and injection-molding resin (so-called insert molding).

[0004] Japanese Patent Application Laid-Open No. 2004-308735, Japanese Patent Application Laid-Open No. 2002-286042, Japanese Patent Application Laid-Open No. 2022-146905

[0005] When the resin-molded insulated rolling bearing is in the state of a single bearing before being attached to the rotating shaft 31 or the housing 30, special care is required to prevent hard objects from coming into contact with the resin layer 51b.

[0006] In other words, as shown in Figure 12, the resin-molded insulated rolling bearing has a structure in which the surface of the outer ring body 51a is covered with a resin layer 51b. Therefore, when carrying the bearing or assembling it onto the rotating shaft 31 or housing 30, the outer circumference of the outer ring 51 may come into contact with a hard object, potentially damaging the resin layer 51b. If the resin layer 51b is damaged, the electrical insulation of that part decreases, and the corrosion prevention performance of the bearing deteriorates. For this reason, when the bearing is in its standalone state before being attached to the rotating shaft 31 or housing 30, it is necessary to handle it in a way that prevents hard objects from coming into contact with the resin layer 51b, requiring special care in handling.

[0007] Furthermore, in resin-molded insulated rolling bearings as shown in Figure 12, the mating surface 57 of the outer ring 51 (the surface that fits with the inner circumference of the housing 30) is provided in a resin layer 51b. However, since the resin forming this resin layer 51b is prone to dimensional changes due to temperature and humidity, there was a problem in that the dimensional accuracy of the mating surface 57 was unstable.

[0008] The problem that this invention aims to solve is to provide an insulated rolling bearing that is easy to handle and has stable dimensional accuracy of the mating surface.

[0009] To solve the above problems, this invention provides an insulated rolling bearing having the following configuration: [Configuration 1] An insulated rolling bearing having an outer ring, an inner ring disposed radially inward of the outer ring, and a plurality of rolling elements that roll in contact with an outer ring raceway groove formed on the inner circumference of the outer ring and an inner ring raceway groove formed on the outer circumference of the inner ring, wherein the outer ring is formed of a steel outer diameter side ring member having a cylindrical fitting surface on its outer circumference, a steel inner diameter side ring member having the outer ring raceway groove on its inner circumference, and a resin intermediate resin layer that radially connects the outer diameter side ring member and the inner diameter side ring member.

[0010] With this configuration, the intermediate resin layer is located inside the outer ring, rather than on its outer circumference. Therefore, even if the outer circumference of the outer ring strikes a hard object, there is no risk of damage to the intermediate resin layer. This makes handling the bearing as a standalone unit before mounting it to the rotating shaft or housing easier. Furthermore, since the mating surface of the outer ring (the surface that fits with the inner circumference of the housing) is located on the steel outer diameter ring member rather than the resin layer, the dimensional accuracy of the mating surface is stable.

[0011] [Configuration 2] The insulating rolling bearing according to Configuration 1, wherein the outer diameter side ring member further has a pair of chamfered portions with a cross-sectional arc shape whose outer diameter gradually decreases outward from the mating surface in the axial direction, and a pair of width surfaces perpendicular to the axial direction that extend radially inward from the pair of chamfered portions.

[0012] By adopting this configuration, the bearing can be positioned axially by abutting the width surface of the outer diameter ring member (i.e., the steel member) against the positioning step on the inner circumference of the housing in the axial direction. Therefore, when positioning the bearing axially, there is no risk of the resin layer being damaged by the axial load acting from the positioning step on the inner circumference of the housing, and no special care is required.

[0013] [Configuration 3] The insulating rolling bearing according to Configuration 2, wherein at least one axial end of the intermediate resin layer is formed in a planar shape perpendicular to the axial direction and on the same plane as the width surface.

[0014] This configuration is achieved by forming an intermediate resin layer between the outer diameter ring member and the inner diameter ring member by insert molding. Specifically, the outer diameter ring member and the inner diameter ring member are set in a mold, the mold is closed, and resin is injected to obtain the intermediate resin layer. The axial end of the intermediate resin layer thus obtained is a planar shape perpendicular to the axial direction and coplane with the width surface of the outer diameter ring member.

[0015] [Configuration 4] The insulating rolling bearing according to Configuration 2 or 3, wherein the inner diameter side ring member has an axial end face that lies on the same plane as the width surface, and the outer circumference of the inner diameter side ring member has a shape in which the outer diameter changes along the axial direction such that the outer diameter of the axial end face is smaller than the outer diameter at the axial center of the inner diameter side ring member.

[0016] This configuration prevents the radial thickness of the inner diameter ring member from being too small at its axial center (i.e., at the position of the outer ring raceway groove), while ensuring that the outer diameter of the axial end face of the inner diameter ring member is smaller than the inner diameter of the positioning step on the inner circumference of the housing. Therefore, when the bearing is assembled into the housing, it is possible to reliably prevent the axial end face of the inner diameter ring member from coming into contact with the positioning step on the inner circumference of the housing and becoming electrically conductive.

[0017] [Configuration 5] An insulated rolling bearing according to any one of Configurations 1 to 3, wherein a resin flange portion is integrally formed at at least one axial end of the intermediate resin layer, covering the axial end face of the inner diameter ring member so that the inner diameter ring member is not exposed when viewed from the axial direction.

[0018] By adopting this configuration, the resin flange portion covers the axial end face of the inner diameter ring member, which reliably prevents the inner diameter ring member from contacting the positioning step on the inner circumference of the housing and becoming electrically conductive when the bearing is assembled to the housing.

[0019] [Configuration 6] An insulating rolling bearing according to any one of Configurations 1 to 5, wherein a bonding surface is formed on the inner circumference of the outer diameter ring member to bond with the intermediate resin layer, and the bonding surface has a resin locking shape that prevents relative axial movement between the outer diameter ring member and the intermediate resin layer.

[0020] By adopting this configuration, the joint surface between the outer diameter ring member and the intermediate resin layer has a resin locking shape that prevents relative axial movement between the outer diameter ring member and the intermediate resin layer, thus preventing the joint between the outer diameter ring member and the intermediate resin layer from coming undone due to axial external force.

[0021] [Configuration 7] The insulated rolling bearing according to Configuration 6, wherein the resin locking shape is a stepped shape having a small inner diameter portion with a constant inner diameter along the axial direction, a large inner diameter portion having an inner diameter larger than the small inner diameter portion, and an inner diameter stepped portion connecting the small inner diameter portion and the large inner diameter portion.

[0022] [Configuration 8] The resin locking shape is a rough turned surface in which a number of turning marks extending in the circumferential direction are formed adjacent to each other in the axial direction, thereby giving the surface roughness Ra in the axial direction to 10 μm or more, as described in Configuration 6.

[0023] [Configuration 9] The insulating rolling bearing according to Configuration 6, wherein the resin locking shape is a plurality of circumferential grooves having a groove depth of 0.3 mm or more.

[0024] [Configuration 10] An insulating rolling bearing according to any one of Configurations 1 to 9, wherein a bonding surface is formed on the outer circumference of the inner diameter side ring member for bonding with the intermediate resin layer, and the bonding surface has a resin locking shape that prevents relative axial movement between the inner diameter side ring member and the intermediate resin layer.

[0025] By adopting this configuration, the joint surface between the inner diameter ring member and the intermediate resin layer has a resin locking shape that prevents relative axial movement between the inner diameter ring member and the intermediate resin layer, thus preventing the joint between the inner diameter ring member and the intermediate resin layer from coming undone due to axial external force.

[0026] [Configuration 11] The insulated rolling bearing according to Configuration 10, wherein the resin locking shape is a stepped shape having a large outer diameter portion with a constant outer diameter along the axial direction, a small outer diameter portion having a smaller outer diameter than the large outer diameter portion, and an outer diameter stepped portion connecting the large outer diameter portion and the small outer diameter portion.

[0027] [Configuration 12] The resin locking shape is a rough turned surface in which a number of turning marks extending in the circumferential direction are formed adjacent to each other in the axial direction, thereby giving the surface roughness Ra in the axial direction to 10 μm or more, as described in Configuration 10.

[0028] [Configuration 13] The insulating rolling bearing according to Configuration 10, wherein the resin locking shape is a plurality of circumferential grooves having a groove depth of 0.3 mm or more.

[0029] [Configuration 14] The insulating rolling bearing according to any one of Configurations 1 to 13, wherein the intermediate resin layer is formed of a resin composition containing an elastomer.

[0030] By adopting this configuration, the intermediate resin layer has rubber elasticity, which suppresses the transmission of vibrations between the outer diameter ring member and the inner diameter ring member, thereby reducing vibrations and noise generated from the bearing.

[0031] [Configuration 15] An insulated rolling bearing comprising an outer ring, an inner ring disposed radially inward of the outer ring, and a plurality of rolling elements that roll in contact with an outer ring raceway groove formed on the inner circumference of the outer ring and an inner ring raceway groove formed on the outer circumference of the inner ring, wherein the inner ring is formed of a steel inner diameter side ring member having a cylindrical fitting surface on its inner circumference, a steel outer diameter side ring member having the inner ring raceway groove on its outer circumference, and a resin intermediate resin layer connecting the inner diameter side ring member and the outer diameter side ring member.

[0032] With this configuration, the intermediate resin layer is located inside the inner ring, rather than on its inner circumference. Therefore, even if the inner circumference of the inner ring comes into contact with a hard object, there is no risk of damage to the intermediate resin layer. This makes it easy to handle the bearing in its standalone state before mounting it to a fixed shaft or rotating cylinder. Furthermore, since the mating surface of the inner ring (the surface that fits with the outer circumference of the fixed shaft) is located on a steel inner diameter ring member rather than a resin layer, the dimensional accuracy of the mating surface is stable.

[0033] In this invention, the insulating rolling bearing has an intermediate resin layer located inside the outer ring, rather than on its outer circumference. Therefore, even if the outer circumference of the outer ring strikes a hard object, there is no risk of damage to the intermediate resin layer. As a result, the bearing is easy to handle in its standalone state before being mounted on the rotating shaft or housing. Furthermore, since the mating surface of the outer ring (the surface that fits with the inner circumference of the housing) is located on a steel outer diameter ring member rather than a resin layer, the dimensional accuracy of the mating surface is stable.

[0034] Figure 1 shows a partial cross-sectional view of an insulated rolling bearing according to the first embodiment of this invention, a cross-sectional view along the line II-II in Figure 1, a cross-sectional view of the insulated rolling bearing shown in Figure 2 showing the insulated rolling bearing assembled to the rotating shaft and housing, a diagram showing an insulated rolling bearing according to the second embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the third embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the fourth embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the fifth embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the sixth embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the seventh embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the eighth embodiment of this invention corresponding to Figure 3, a diagram showing an insulated rolling bearing according to the ninth embodiment of this invention, and a diagram showing a conventional resin-molded insulated rolling bearing.

[0035] Figures 1 and 2 show an insulated rolling bearing according to a first embodiment of the present invention. This insulated rolling bearing comprises an outer ring 1, an inner ring 2 arranged coaxially radially inward of the outer ring 1, a plurality of rolling elements 3 fitted between the outer ring 1 and the inner ring 2 at circumferential intervals, and an annular cage 4 that maintains the circumferential intervals of the plurality of rolling elements 3.

[0036] The axial direction is the direction parallel to the central axis of the outer ring 1 (the central axis of the bearing), the radial direction is the direction perpendicular to the central axis of the outer ring 1, and the circumferential direction is the direction along the circumference that revolves around the central axis of the outer ring 1. Furthermore, the axial inner side is the side that approaches the center position of the rolling element 3 along the axial direction, and the axial outer side is the side that moves away from the center position of the rolling element 3 along the axial direction.

[0037] As shown in Figure 2, the rolling element 3 rolls and makes contact with the outer ring raceway groove 5 formed on the inner circumference of the outer ring 1 and the inner ring raceway groove 6 formed on the outer circumference of the inner ring 2. The rolling element 3 is made of steel, and in this case, it is a steel ball.

[0038] The outer ring 1 is formed from an outer diameter ring member 1a made of steel, an inner diameter ring member 1b made of steel, and a resin intermediate resin layer 1c connecting the outer diameter ring member 1a and the inner diameter ring member 1b. The intermediate resin layer 1c is formed by resin insert molding. Specifically, the outer diameter ring member 1a and the inner diameter ring member 1b shown in Figure 2 are set in a mold (not shown), and molten resin is injected into the annular cavity (a space with the same shape as the intermediate resin layer 1c) formed between the outer diameter ring member 1a and the inner diameter ring member 1b to form the intermediate resin layer 1c.

[0039] The outer diameter ring member 1a has a fitting surface 7 that fits onto the inner circumference of the housing 30 (see Figure 3), a pair of chamfered portions 8 with a cross-sectional arc shape whose outer diameter gradually decreases axially outward from the fitting surface 7, and a pair of width surfaces 9 that are perpendicular to the axial direction and extend radially inward from the pair of chamfered portions 8. The fitting surface 7 is a cylindrical surface formed on the outer circumference of the outer diameter ring member 1a with a constant outer diameter along the axial direction. The width surfaces 9 are planes perpendicular to the axial direction.

[0040] The inner circumference of the inner diameter ring member 1b has an outer ring raceway groove 5 and a pair of outer ring shoulder surfaces 11 adjacent to the outer ring raceway groove 5 on both sides in the axial direction. The outer ring raceway groove 5 is a groove with a circular arc cross-section formed at the axial center of the inner circumference of the inner diameter ring member 1b. The outer ring shoulder surfaces 11 are cylindrical surfaces formed on both sides of the outer ring raceway groove 5. The axial outer ends of the outer ring shoulder surfaces 11 are connected to the axial end surface 12 via chamfered portions. The axial end surface 12 is a plane perpendicular to the axial direction that is on the same plane as the width surface 9 of the outer diameter ring member 1a. The inner ring raceway groove 6 is a groove with a circular arc cross-section formed at the axial center of the outer circumference of the inner ring 2.

[0041] The axial end of the intermediate resin layer 1c is formed in a planar shape perpendicular to the axial direction, which is on the same plane as the width surface 9 of the outer diameter ring member 1a. The intermediate resin layer 1c is formed of an electrically insulating resin composition. Preferably, the resin composition forming the intermediate resin layer 1c is one that incorporates an elastomer having rubber elasticity. The elastomer is, for example, a thermoplastic elastomer. Alternatively, the resin composition forming the intermediate resin layer 1c may be one in which a fiber reinforcing material such as glass fiber or aramid fiber is added to a resin material such as polyphenylene sulfide resin (PPS) or polyphthalamide resin (PPA). The resin composition forming the intermediate resin layer 1c has a heat resistance temperature of 120°C or higher and a density of 1.0 × 10 １６ It is preferable to use a material with a volume resistivity of Ωm or greater.

[0042] The outer diameter of the outer ring 1 (the diameter of the mating surface 7) can be set to a size of, for example, 60 mm or more, preferably 65 mm or more, 90 mm or less, and preferably 80 mm or less. This insulated rolling bearing can be used as a rolling bearing to support the rotating shaft 31 of an electric motor for driving electric vehicles such as BEVs (battery electric vehicles), HEVs (hybrid electric vehicles), and PHEVs (plug-in hybrid vehicles), or as a rolling bearing to support the rotating shaft 31 of a reduction gear (e.g., e-Axle) that reduces the rotation of the electric motor.

[0043] As shown in Figure 3, a bonding surface 14 is formed on the inner circumference of the outer diameter ring member 1a, which is joined to the intermediate resin layer 1c. The bonding surface 14 is bonded to the radially outer surface of the intermediate resin layer 1c by resin insert molding. Similarly, a bonding surface 15 is formed on the outer circumference of the inner diameter ring member 1b, which is joined to the intermediate resin layer 1c. The bonding surface 15 is bonded to the radially inner surface of the intermediate resin layer 1c by resin insert molding. Before injection molding the intermediate resin layer 1c, the outer diameter ring member 1a is pre-processed (processing of the fitting surface 7, chamfered portion 8, width surface 9, bonding surface 14, etc.) and heat-treated, and the inner diameter ring member 1b is pre-processed (processing of the outer ring raceway groove 5, outer ring shoulder surface 11, axial end surface 12, etc.) and heat-treated.

[0044] A joint surface 14 of the outer diameter side ring member 1a with the intermediate resin layer 1c has a resin locking shape that prevents relative movement in the axial direction between the outer diameter side ring member 1a and the intermediate resin layer 1c. In this embodiment, the resin locking shape of the joint surface 14 is a stepped shape including a small inner diameter portion 16 having a constant inner diameter along the axial direction, a pair of large inner diameter portions 17 each having an inner diameter larger than that of the small inner diameter portion 16, and a pair of inner diameter stepped portions 18 connecting the small inner diameter portion 16 and the pair of large inner diameter portions 17.

[0045] The small inner diameter portion 16 is formed at the axial center of the inner circumference of the outer diameter side ring member 1a, and the pair of inner diameter stepped portions 18 are provided on both axial sides of the small inner diameter portion 16. Each of the pair of inner diameter stepped portions 18 is a step that increases in diameter from the axially inner side toward the axially outer side.

[0046] A joint surface 15 of the inner diameter side ring member 1b with the intermediate resin layer 1c also has a resin locking shape that prevents relative movement in the axial direction between the inner diameter side ring member 1b and the intermediate resin layer 1c. In this embodiment, the resin locking shape of the joint surface 15 is a stepped shape including a large outer diameter portion 19 having a constant outer diameter along the axial direction, a pair of small outer diameter portions 20 each having an outer diameter smaller than that of the large outer diameter portion 19, and a pair of outer diameter stepped portions 21 connecting the large outer diameter portion 19 and the pair of small outer diameter portions 20.

[0047] The large outer diameter portion 19 is formed at the axial center of the outer circumference of the inner diameter side ring member 1b, and the pair of outer diameter stepped portions 21 are provided on both axial sides of the large outer diameter portion 19. Each of the pair of outer diameter stepped portions 21 is a step that decreases in diameter from the axially inner side toward the axially outer side. Here, the outer circumference of the inner diameter side ring member 1b has a shape in which the outer diameter changes along the axial direction such that the outer diameter of the axial end face 12 (the outer diameter of the small outer diameter portion 20) is smaller than the outer diameter at the axial center of the inner diameter side ring member 1b (the outer diameter of the large outer diameter portion 19).

[0048] As shown in Figure 2, in this insulated rolling bearing, the intermediate resin layer 1c is located inside the outer ring 1, rather than on its outer circumference. Therefore, even if the outer circumference of the outer ring 1 strikes a hard object, there is no risk of damage to the intermediate resin layer 1c. This makes it easy to handle the bearing in its standalone state before mounting it to the rotating shaft 31 or housing 30, as shown in Figure 3. Furthermore, since the mating surface 7 of the outer ring 1 (the surface that fits with the inner circumference of the housing 30, as shown in Figure 3) is located on the steel outer diameter ring member 1a rather than the resin layer, the dimensional accuracy of the mating surface 7 is stable.

[0049] Furthermore, in this insulated rolling bearing, the intermediate resin layer 1c is located inside the outer ring 1 rather than on the outer circumference of the outer ring 1. Therefore, even if the bearing is subjected to a strong impact, such as by being dropped, the intermediate resin layer 1c is less likely to be affected by the impact. As a result, the required strength of the intermediate resin layer 1c can be kept low, and even if welds (junctions of molten resin) or voids (air bubbles) occur during the resin molding of the intermediate resin layer 1c, it is easier to ensure the required strength of the intermediate resin layer 1c.

[0050] Furthermore, as shown in Figure 2, this insulated rolling bearing has a pair of width surfaces 9 perpendicular to the axial direction on the outer diameter side ring member 1a. Therefore, the bearing can be positioned axially by abutting the width surfaces 9 of the outer diameter side ring member 1a (i.e., the steel member) against the positioning step 32 on the inner circumference of the housing 30 shown in Figure 3. As a result, when positioning the bearing axially, there is no risk of the intermediate resin layer 1c being damaged by the axial load acting from the positioning step 32 on the inner circumference of the housing 30, and no special care is required.

[0051] Furthermore, as shown in Figure 3, this insulated rolling bearing has an outer diameter that changes along the axial direction such that the outer diameter of the axial end face 12 of the inner diameter ring member 1b is smaller than the outer diameter of the inner diameter ring member 1b at its axial center. This prevents the radial thickness at the axial center of the inner diameter ring member 1b (i.e., the position of the outer ring raceway groove 5) from being too small, while ensuring that the outer diameter of the axial end face 12 of the inner diameter ring member 1b is smaller than the inner diameter of the positioning step 32 on the inner circumference of the housing 30. Therefore, when the bearing is assembled to the housing 30, it is possible to reliably prevent the axial end face 12 of the inner diameter ring member 1b from coming into contact with the positioning step 32 on the inner circumference of the housing 30 and becoming electrically conductive.

[0052] Furthermore, as shown in Figure 3, the insulated rolling bearing has a resin locking shape (in this case, a stepped shape having a small inner diameter portion 16, a large inner diameter portion 17, and an inner diameter stepped portion 18) at the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c that prevents relative axial movement between the outer diameter ring member 1a and the intermediate resin layer 1c. This makes it possible to prevent the joint between the outer diameter ring member 1a and the intermediate resin layer 1c from coming undone due to external axial forces.

[0053] Similarly, as shown in Figure 3, the insulated rolling bearing has a resin locking shape (here, a stepped shape having a large outer diameter portion 19, a small outer diameter portion 20, and an outer diameter stepped portion 21) at the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c that prevents relative axial movement between the inner diameter ring member 1b and the intermediate resin layer 1c, thus preventing the joint between the inner diameter ring member 1b and the intermediate resin layer 1c from coming loose due to external axial forces.

[0054] Furthermore, since the intermediate resin layer 1c shown in Figure 3 of this insulated rolling bearing is formed from a resin composition containing an elastomer, the intermediate resin layer 1c has rubber elasticity. Therefore, it is possible to suppress the transmission of vibrations between the outer diameter ring member 1a and the inner diameter ring member 1b, thereby reducing vibrations and noise generated from the bearing.

[0055] Figure 4 shows 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 joint surface 14 between the outer diameter side ring member 1a and the intermediate resin layer 1c is a cylindrical surface with a constant inner diameter over the entire axial width of the outer diameter side ring member 1a; all other configurations are the same as those of the first embodiment. Therefore, the parts corresponding to the first embodiment are given the same reference numerals and their description is omitted.

[0056] Figure 5 shows an insulated rolling bearing according to a third embodiment of the present invention. Compared to the first embodiment, the third embodiment differs in the resin locking shape of the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c, and in the resin locking shape of the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c. The other configurations are the same as those of the first embodiment. Therefore, the parts corresponding to the first embodiment are given the same reference numerals and their description is omitted.

[0057] In Figure 5, the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c is a cylindrical surface with a constant inner diameter over the entire axial width of the outer diameter ring member 1a. Here, the joint surface 14 is a rough turned surface with a surface roughness Ra of 10 μm or more along the axial direction, formed by numerous turning marks extending in the circumferential direction adjacent to each other in the axial direction. The resin forming the intermediate resin layer 1c enters into these numerous turning marks on the rough turned surface, thereby preventing relative axial movement between the outer diameter ring member 1a and the intermediate resin layer 1c. The surface roughness Ra of a typical turned surface is approximately 0.8 μm to 1.6 μm.

[0058] Similarly, the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c is a cylindrical surface with a constant outer diameter over the entire axial width of the inner diameter ring member 1b. Here, the joint surface 15 is a rough turned surface with a surface roughness Ra of 10 μm or more along the axial direction, formed by numerous turning marks extending in the circumferential direction adjacent to each other in the axial direction. The resin forming the intermediate resin layer 1c enters into the numerous turning marks on this rough turned surface, thereby preventing relative movement of the inner diameter ring member 1b and the intermediate resin layer 1c in the axial direction.

[0059] In this embodiment, the insulated rolling bearing employs a rough turned surface as the resin locking shape of the joint surface 14 that prevents relative axial movement between the outer diameter ring member 1a and the intermediate resin layer 1c. This surface has a surface roughness Ra of 10 μm or more along the axial direction, formed by numerous turning marks extending in the circumferential direction adjacent to each other in the axial direction. Therefore, the processing of the joint surface 14 is simple and low cost. Similarly, the resin locking shape of the joint surface 15 that prevents relative axial movement between the inner diameter ring member 1b and the intermediate resin layer 1c employs a rough turned surface with a surface roughness Ra of 10 μm or more along the axial direction, formed by numerous turning marks extending in the circumferential direction adjacent to each other in the axial direction. Therefore, the processing of the joint surface 15 is simple and low cost.

[0060] Figure 6 shows an insulated rolling bearing according to the fourth embodiment of the present invention. Compared to the first embodiment, the fourth embodiment differs in the resin locking shape of the joint surface 14 between the outer diameter side ring member 1a and the intermediate resin layer 1c, and in the resin locking shape of the joint surface 15 between the inner diameter side ring member 1b and the intermediate resin layer 1c, but the other configurations are the same as the first embodiment. Therefore, the parts corresponding to the first embodiment are given the same reference numerals and their description is omitted.

[0061] In Figure 6, the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c has a plurality of circumferential grooves 22 having a groove depth of 0.3 mm to 1.0 mm. The resin forming the intermediate resin layer 1c enters these circumferential grooves 22, thereby preventing relative axial movement between the outer diameter ring member 1a and the intermediate resin layer 1c. The circumferential grooves 22 can be circumferential grooves with a V-shaped cross-section or spiral grooves with a V-shaped cross-section.

[0062] Similarly, the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c also has a plurality of circumferential grooves 23 having a groove depth of 0.3 mm to 1.0 mm. The resin forming the intermediate resin layer 1c enters these circumferential grooves 23, thereby preventing relative axial movement between the inner diameter ring member 1b and the intermediate resin layer 1c. The circumferential grooves 23 can be circular grooves with a V-shaped cross-section or spiral grooves with a V-shaped cross-section.

[0063] Figure 7 shows an insulated rolling bearing according to a fifth embodiment of the present invention. Compared to the first embodiment, the fifth embodiment differs in the resin locking shape of the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c, and in the resin locking shape of the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c. The other configurations are the same as those of the first embodiment. Therefore, the parts corresponding to the first embodiment are given the same reference numerals and their description is omitted.

[0064] In Figure 7, the joint surface 14 of the outer diameter ring member 1a with the intermediate resin layer 1c is an inclined surface in which the inner diameter gradually increases from the side closer to the width surface 9 that abuts against the positioning step 32 on the inner circumference of the housing 30 (right side in the figure) to the side further away (left side in the figure). This inclination of the inclined surface prevents the relative axial movement of the outer diameter ring member 1a and the intermediate resin layer 1c (in this case, the relative movement of the outer diameter ring member 1a and the intermediate resin layer 1c due to an axial load acting from the inner diameter ring member 1b to the outer diameter ring member 1a in a direction that presses the width surface 9 of the outer diameter ring member 1a against the positioning step 32 on the inner circumference of the housing 30).

[0065] Similarly, the joint surface 15 of the inner diameter ring member 1b with the intermediate resin layer 1c is an inclined surface in which the outer diameter gradually increases from the side closer to the width surface 9 of the outer diameter ring member 1a (right side in the figure) to the side further away (left side in the figure) from the width surface 9 of the outer diameter ring member 1a that abuts against the positioning step 32 on the inner circumference of the housing 30. This inclination of the inclined surface prevents the relative axial movement of the inner diameter ring member 1b and the intermediate resin layer 1c (in this case, the relative movement of the inner diameter ring member 1b and the intermediate resin layer 1c due to an axial load acting from the inner diameter ring member 1b to the outer diameter ring member 1a in a direction that presses the width surface 9 of the outer diameter ring member 1a against the positioning step 32 on the inner circumference of the housing 30).

[0066] The outer circumference of the inner diameter ring member 1b is shaped such that its outer diameter changes along the axial direction, so that the outer diameter of the axial end face 12, located on the same side (right side in the figure) as the width surface 9 of the outer diameter ring member 1a that abuts against the positioning step 32 on the inner circumference of the housing 30, is smaller than the outer diameter of the inner diameter ring member 1b at its axial center. This prevents the radial thickness of the inner diameter ring member 1b at its axial center (i.e., the position of the outer ring raceway groove 5) from being too small, while ensuring that the outer diameter of the axial end face 12 of the inner diameter ring member 1b is smaller than the inner diameter of the positioning step 32 on the inner circumference of the housing 30. As a result, when the bearing is assembled to the housing 30, it is possible to reliably prevent the axial end face 12 of the inner diameter ring member 1b from contacting the positioning step 32 on the inner circumference of the housing 30 and becoming electrically conductive.

[0067] Figure 8 shows an insulated rolling bearing according to the sixth embodiment of the present invention. Compared to the first embodiment, the sixth embodiment differs in the resin locking shape of the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c, and in the resin locking shape of the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c, but the other configurations are the same as the first embodiment. Therefore, the parts corresponding to the first embodiment are given the same reference numerals and their description is omitted.

[0068] In Figure 8, the resin locking shape of the joint surface 14 between the outer diameter ring member 1a and the intermediate resin layer 1c is a stepped shape having a small inner diameter portion 16 with a constant inner diameter along the axial direction, a large inner diameter portion 17 having an inner diameter larger than the small inner diameter portion 16, and an inner diameter stepped portion 18 connecting the small inner diameter portion 16 and the large inner diameter portion 17.

[0069] The large inner diameter portion 17 is formed in a region that includes the axial center of the inner circumference of the outer diameter side ring member 1a. The inner diameter step portion 18 is formed at a position offset from the large inner diameter portion 17 to the side closer to the width surface 9 that abuts against the positioning step portion 32 on the inner circumference of the housing 30 (to the right in the figure). This inner diameter step portion 18 prevents the relative axial movement of the outer diameter side ring member 1a and the intermediate resin layer 1c (in this case, the relative movement of the outer diameter side ring member 1a and the intermediate resin layer 1c due to an axial load acting from the inner diameter side ring member 1b to the outer diameter side ring member 1a in a direction that presses the width surface 9 of the outer diameter side ring member 1a against the positioning step portion 32 on the inner circumference of the housing 30).

[0070] Similarly, the resin locking shape of the joint surface 15 between the inner diameter ring member 1b and the intermediate resin layer 1c is a stepped shape having a large outer diameter portion 19 with a constant outer diameter along the axial direction, a small outer diameter portion 20 having a smaller outer diameter than the large outer diameter portion 19, and an outer diameter stepped portion 21 connecting the large outer diameter portion 19 and the small outer diameter portion 20.

[0071] The large outer diameter portion 19 is formed in a region including the axial center of the outer circumference of the inner diameter ring member 1b. The outer diameter step portion 21 is formed at a position offset from the large outer diameter portion 19, closer to the width surface 9 of the outer diameter ring member 1a that abuts against the positioning step portion 32 on the inner circumference of the housing 30 (to the right in the figure). This outer diameter step portion 21 prevents the relative axial movement of the inner diameter ring member 1b and the intermediate resin layer 1c (in this case, the relative movement of the inner diameter ring member 1b and the intermediate resin layer 1c due to an axial load acting from the inner diameter ring member 1b to the outer diameter ring member 1a in a direction that presses the width surface 9 of the outer diameter ring member 1a against the positioning step portion 32 on the inner circumference of the housing 30).

[0072] The outer circumference of the inner diameter ring member 1b is shaped such that its outer diameter changes along the axial direction, so that the outer diameter of the axial end face 12, located on the same side (right side in the figure) as the width surface 9 of the outer diameter ring member 1a that abuts against the positioning step 32 on the inner circumference of the housing 30, is smaller than the outer diameter of the inner diameter ring member 1b at its axial center. This prevents the radial thickness of the inner diameter ring member 1b at its axial center (i.e., the position of the outer ring raceway groove 5) from being too small, while ensuring that the outer diameter of the axial end face 12 of the inner diameter ring member 1b is smaller than the inner diameter of the positioning step 32 on the inner circumference of the housing 30. As a result, when the bearing is assembled to the housing 30, it is possible to reliably prevent the axial end face 12 of the inner diameter ring member 1b from contacting the positioning step 32 on the inner circumference of the housing 30 and becoming electrically conductive.

[0073] Figure 9 shows an insulated rolling bearing according to the seventh embodiment of the present invention. The seventh embodiment differs from the third embodiment only in that a resin flange portion 24 is integrally formed at one axial end of the intermediate resin layer 1c; the other configurations are the same as those of the third embodiment. Therefore, the parts corresponding to the third embodiment are given the same reference numerals and their description is omitted.

[0074] In Figure 9, of the axial end faces 12 on both sides of the inner diameter ring member 1b, the axial end face 12 located on the same side (right side in the figure) as the width face 9 of the outer diameter ring member 1a that abuts against the positioning step 32 on the inner circumference of the housing 30 is provided axially inward from the width face 9 of the outer diameter ring member 1a. The resin flange portion 24 of the intermediate resin layer 1c is formed to cover the axial end face 12 of the inner diameter ring member 1b so that the inner diameter ring member 1b is not exposed when viewed from the axial direction.

[0075] In this embodiment, the insulated rolling bearing has a resin flange portion 24 that covers the axial end face 12 of the inner diameter side ring member 1b. Therefore, when the bearing is assembled to the housing 30, it is possible to reliably prevent the inner diameter side ring member 1b from coming into contact with the positioning step portion 32 on the inner circumference of the housing 30 and becoming electrically conductive.

[0076] Figure 10 shows an insulated rolling bearing according to the eighth embodiment of the present invention. The eighth embodiment differs from the third embodiment only in that resin flange portions 24 are provided at both axial ends of the intermediate resin layer 1c; the other configurations are the same as those of the third embodiment. Therefore, the parts corresponding to the third embodiment are given the same reference numerals and their description is omitted.

[0077] In Figure 10, the axial end faces 12 on both sides of the inner diameter ring member 1b are positioned axially inward from the width surface 9 of the outer diameter ring member 1a. The resin flange portion 24 of the intermediate resin layer 1c is formed to cover the axial end faces 12 on both sides of the inner diameter ring member 1b so that the inner diameter ring member 1b is not exposed when viewed from the axial direction.

[0078] In this embodiment of the insulated rolling bearing, similar to the seventh embodiment, the resin flange portion 24 covers the axial end face 12 of the inner diameter side ring member 1b. Therefore, when the bearing is assembled to the housing 30, it is possible to reliably prevent the inner diameter side ring member 1b from contacting the positioning step portion 32 on the inner circumference of the housing 30 and becoming electrically conductive. Furthermore, since the resin flange portion 24 is provided on both axial sides, it is possible to ensure electrical insulation between the housing 30 and the inner diameter side ring member 1b regardless of the orientation in which the bearing is assembled.

[0079] In the above embodiments, an example was given in which an intermediate resin layer 1c is provided on the outer ring 1. However, it is also possible to reverse the relationship between the radially outer and radially inner sides in the above embodiments. For example, as shown in the ninth embodiment in Figure 11, an intermediate resin layer 2c may be provided on the inner ring 2. In Figure 11, the inner ring 2 is formed of a steel inner diameter side ring member 2a having a cylindrical fitting surface 25 on its inner circumference, a steel outer diameter side ring member 2b having an inner ring raceway groove 6 on its outer circumference, and a resin intermediate resin layer 2c connecting the inner diameter side ring member 2a and the outer diameter side ring member 2b.

[0080] In this embodiment of the insulated rolling bearing, the intermediate resin layer 2c is provided inside the inner ring 2, rather than on the inner circumference of the inner ring 2. Therefore, even if the inner circumference of the inner ring 2 comes into contact with a hard object, there is no risk of damage to the intermediate resin layer 2c. As a result, the bearing can be easily handled in its standalone state before being mounted on a fixed shaft or rotating cylinder (not shown). Furthermore, since the mating surface 25 of the inner ring 2 (the surface that fits with the outer circumference of a fixed shaft (not shown)) is provided on the steel inner diameter side ring member 2a rather than the resin layer, the dimensional accuracy of the mating surface is stable.

[0081] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.

[0082] 1 Outer ring 1a Outer diameter side ring member 1b Inner diameter side ring member 1c Intermediate resin layer 2 Inner ring 2a Inner diameter side ring member 2b Outer diameter side ring member 2c Intermediate resin layer 3 Rolling element 5 Outer ring raceway groove 6 Inner ring raceway groove 7 Fitting surface 8 Chamfered portion 9 Width surface 12 Axial end surface 14 Joint surface 15 Joint surface 16 Small inner diameter portion 17 Large inner diameter portion 18 Inner diameter step portion 19 Large outer diameter portion 20 Small outer diameter portion 21 Outer diameter step portion 22 Circumferential groove 23 Circumferential groove 24 Resin flange portion 25 Fitting surface

Claims

1. An insulated rolling bearing comprising an outer ring (1), an inner ring (2) positioned radially inward of the outer ring (1), and a plurality of rolling elements (3) that roll in contact with an outer ring raceway groove (5) formed on the inner circumference of the outer ring (1) and an inner ring raceway groove (6) formed on the outer circumference of the inner ring (2), wherein the outer ring (1) is formed of a steel outer diameter side ring member (1a) having a cylindrical fitting surface (7) on its outer circumference, a steel inner diameter side ring member (1b) having the outer ring raceway groove (5) on its inner circumference, and a resin intermediate resin layer (1c) that radially connects the outer diameter side ring member (1a) and the inner diameter side ring member (1b).

2. The insulating rolling bearing according to claim 1, wherein the outer diameter side ring member (1a) further comprises a pair of chamfered portions (8) with a cross-sectional arc shape whose outer diameter gradually decreases toward the axial side from the mating surface (7), and a pair of width surfaces (9) perpendicular to the axial direction that extend radially inward from the pair of chamfered portions (8).

3. The insulating rolling bearing according to claim 2, wherein at least one axial end of the intermediate resin layer (1c) is formed in a planar shape perpendicular to the axial direction and on the same plane as the width surface (9).

4. The insulated rolling bearing according to claim 2 or 3, wherein the inner diameter side ring member (1b) has an axial end face (12) that is in the same plane as the width surface (9), and the outer circumference of the inner diameter side ring member (1b) has a shape in which the outer diameter changes along the axial direction such that the outer diameter of the axial end face (12) is smaller than the outer diameter of the inner diameter side ring member (1b) at the axial center.

5. An insulated rolling bearing according to any one of claims 1 to 3, wherein a resin flange portion (24) is integrally formed at at least one axial end of the intermediate resin layer (1c) to cover the axial end face (12) of the inner diameter side ring member (1b) so that the inner diameter side ring member (1b) is not exposed when viewed from the axial direction.

6. An insulating rolling bearing according to any one of claims 1 to 3, wherein a bonding surface (14) is formed on the inner circumference of the outer diameter side ring member (1a) for bonding with the intermediate resin layer (1c), and the bonding surface (14) has a resin locking shape that prevents relative axial movement between the outer diameter side ring member (1a) and the intermediate resin layer (1c).

7. The insulated rolling bearing according to claim 6, wherein the resin locking shape is a stepped shape having a small inner diameter portion (16) with a constant inner diameter along the axial direction, a large inner diameter portion (17) having an inner diameter larger than that of the small inner diameter portion (16), and a stepped portion (18) connecting the small inner diameter portion (16) and the large inner diameter portion (17).

8. The insulating rolling bearing according to claim 6, wherein the resin locking shape is a rough turned surface in which a number of turning marks extending in the circumferential direction are formed adjacently in the axial direction, thereby giving the surface roughness Ra in the axial direction to 10 μm or more.

9. The insulating rolling bearing according to claim 6, wherein the resin locking shape is a plurality of circumferential grooves (22) having a groove depth of 0.3 mm or more.

10. An insulating rolling bearing according to any one of claims 1 to 3, wherein a bonding surface (15) is formed on the outer circumference of the inner diameter side ring member (1b) for bonding with the intermediate resin layer (1c), and the bonding surface (15) has a resin locking shape that prevents relative axial movement between the inner diameter side ring member (1b) and the intermediate resin layer (1c).

11. The insulated rolling bearing according to claim 10, wherein the resin locking shape is a stepped shape having a large outer diameter portion (19) with a constant outer diameter along the axial direction, a small outer diameter portion (20) having an outer diameter smaller than that of the large outer diameter portion (19), and a stepped portion (21) connecting the large outer diameter portion (19) and the small outer diameter portion (20).

12. The insulating rolling bearing according to claim 10, wherein the resin locking shape is a rough turned surface in which a number of turning marks extending in the circumferential direction are formed adjacent to each other in the axial direction, thereby giving the surface roughness Ra in the axial direction to 10 μm or more.

13. The insulating rolling bearing according to claim 10, wherein the resin locking shape is a plurality of circumferential grooves (23) having a groove depth of 0.3 mm or more.

14. The insulating rolling bearing according to any one of claims 1 to 3, wherein the intermediate resin layer (1c) is formed of a resin composition containing an elastomer.

15. An insulated rolling bearing comprising an outer ring (1), an inner ring (2) disposed radially inward of the outer ring (1), and a plurality of rolling elements (3) that roll in contact with an outer ring raceway groove (5) formed on the inner circumference of the outer ring (1) and an inner ring raceway groove (6) formed on the outer circumference of the inner ring (2), wherein the inner ring (2) is formed of a steel inner diameter side ring member (2a) having a cylindrical fitting surface (25) on its inner circumference, a steel outer diameter side ring member (2b) having the inner ring raceway groove (6) on its outer circumference, and a resin intermediate resin layer (2c) connecting the inner diameter side ring member (2a) and the outer diameter side ring member (2b).

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