Insulated rolling bearing unit

Abstract

This insulated rolling bearing unit includes a rolling bearing (1) and an insulated washer (2). An outer race (3) has an outer race width surface (9), an outer circumference cylindrical surface (10), and an outer race chamfered section (11). The outer circumference cylindrical surface (10) is coated with an insulative film (12). The insulated washer (2) has an annular protrusion (14).

Description

Insulated Rolling Bearing Unit

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

[0002] Known electric vehicles (EVs), hybrid electric vehicles (HEVs), and other electric vehicles use electric motors as their driving motors. These electric vehicles use an inverter that converts DC power from a battery into AC power to supply AC power to the electric motor. The frequency of the AC power supplied to the electric motor is set high to increase the efficiency of the electric motor.

[0003] When the frequency of AC power supplied to an electric motor increases, a potential difference occurs between the motor's main shaft and the motor housing, making it easier for current to flow through the rolling bearings that support the motor's main shaft. When current flows through the rolling bearings, sparks can occur between the rolling elements and the raceway surfaces of the rolling bearings, causing gradual damage to the raceway surfaces (electrolytic corrosion).

[0004] Known insulated rolling bearing units that can prevent this electrolytic corrosion are disclosed in Patent Documents 1 and 2. The insulated rolling bearing units in Patent Documents 1 and 2 include a rolling bearing and an annular insulating washer provided axially adjacent to the outer ring of the rolling bearing. The outer ring has an outer ring width face perpendicular to the axial direction formed at the axial end on the insulating washer side, an outer peripheral cylindrical surface with a constant outer diameter along the axial direction, and an outer ring chamfered portion with an arc-shaped cross section connecting the outer peripheral cylindrical surface and the outer ring width face, and the outer peripheral cylindrical surface and outer ring chamfered portion are coated with an insulating coating.

[0005] This insulating rolling bearing unit has an insulating washer provided axially adjacent to the outer ring, allowing for a large axial creepage distance between the outer ring width face and the axial end face of the inner circumference of the housing that positions the outer ring axially, making it possible to ensure stable axial insulation.

[0006] Japanese Utility Model Application Publication No. 5-38420 Japanese Patent Application Publication No. 2021-76227

[0007] Incidentally, when rolling bearings whose outer rings are coated with an insulating coating are mass-produced, the thickness of the insulating coating applied to the outer ring is measured to ensure that the coating is of the designed thickness.

[0008] Here, while the thickness of the insulating coating on the outer peripheral cylindrical surface of the outer ring can be easily measured using an electromagnetic coating thickness meter or similar, it is difficult to measure the thickness of the insulating coating on the chamfered portion of the outer ring using an electromagnetic coating thickness meter or similar because the coating is applied to a surface with a large radius of curvature.

[0009] Therefore, in order to ensure the insulating performance of the insulating coating on the outer ring chamfer, it has been necessary to conduct an insulating performance test (current test) on the insulating coating on the outer ring chamfer.

[0010] The problem to be solved by the present invention is to provide an insulating rolling bearing unit that can stably ensure insulation performance between a housing to which the outer ring is assembled and the outer ring chamfer portion.

[0011] In order to solve the above problems, the present invention provides an insulated rolling bearing unit having the following configuration: [Configuration 1] An insulated rolling bearing unit comprising: an outer ring, an inner ring arranged radially inward of the outer ring, and a plurality of rolling elements installed between the outer ring and the inner ring, and an annular insulating washer provided axially adjacent to the outer ring, wherein the outer ring has an outer ring width face perpendicular to the axial direction formed at the axial end on the insulating washer side, an outer peripheral cylindrical surface having a constant outer diameter along the axial direction, an outer ring chamfered portion formed between the outer peripheral cylindrical surface and the outer ring width face, and an insulating coating coating the outer peripheral cylindrical surface, characterized in that the insulating washer has an annular plate portion axially facing the outer ring width face, and an annular protrusion formed to protrude axially from the radial outer end of the annular plate portion so as to surround the outer ring chamfered portion from the radial outside.

[0012] With this configuration, the insulating washer has an annular protrusion that surrounds the outer ring chamfered portion from the radially outer side, so insulation between the inner periphery of the housing to which the outer ring is assembled and the outer ring chamfered portion can be achieved by the annular protrusion of the insulating washer, without relying on an insulating coating, thereby ensuring stable insulation performance between the housing to which the outer ring is assembled and the outer ring chamfered portion.

[0013] [Configuration 2] The insulating rolling bearing unit according to Configuration 1, wherein the annular projection has a tapered cross-sectional shape in which the radial width gradually decreases toward the tip.

[0014] By adopting this configuration, the annular protrusion of the insulating washer can easily enter the radial gap between the housing to which the outer ring is assembled and the outer ring chamfered portion, allowing the annular protrusion of the insulating washer to reliably surround the outer ring chamfered portion.

[0015] [Configuration 3] The insulated rolling bearing unit according to Configuration 1 or 2, wherein the outer ring has a slightly inclined surface, which has a linear cross section and is inclined at an angle of 10° or less with respect to the outer peripheral cylindrical surface, between the outer peripheral cylindrical surface and the outer ring chamfered portion, the slightly inclined surface is coated with the insulating coating, and the annular protrusion has at its tip an insertion portion that is inserted into an annular gap radially outward of the slightly inclined surface.

[0016] When this configuration is adopted, the tip of the annular protrusion of the insulating washer and the insulating coating coated on the slightly inclined surface of the outer periphery of the outer ring overlap radially, thereby ensuring radial insulation between the outer ring and the housing to which the outer ring is assembled.

[0017] [Configuration 4] The insulating rolling bearing unit according to any one of Configurations 1 to 3, wherein the outer ring chamfered portion is not coated with the insulating coating.

[0018] By adopting this configuration, the area to be coated with the insulating film can be reduced, thereby reducing costs.

[0019] [Configuration 5] The insulating rolling bearing unit according to any one of Configurations 1 to 4, wherein the insulating washer further has a second annular protrusion formed so as to protrude in the axial direction from the radially inner end of the annular plate portion, and the second annular protrusion is fitted onto the inner periphery of the outer ring.

[0020] When this configuration is adopted, the insulating washer and the outer ring can be positioned in the radial direction by fitting the second annular protrusion into the inner periphery of the outer ring.

[0021] [Configuration 6] An insulated rolling bearing unit according to any one of Configurations 1 to 4, wherein an outer ring raceway groove with which the rolling elements roll and make contact, and an annular groove extending circumferentially between the outer ring raceway groove and the outer ring width surface, are formed on the inner circumference of the outer ring, and the insulating washer has an engaging claw portion that engages with the annular groove.

[0022] By adopting this configuration, the engagement between the engaging claw portion and the annular groove holds the insulating washer on the outer ring so that it does not come off the outer ring width surface, making it possible to handle the rolling bearing and insulating washer as an integrated assembly.

[0023] [Configuration 7] The insulating rolling bearing unit according to Configuration 6, wherein a plurality of the engaging claws are provided at intervals in the circumferential direction.

[0024] When this configuration is adopted, the insulating washer and the outer ring can be positioned in the radial direction by the engagement between the multiple engaging claws and the annular groove.

[0025] [Configuration 8] The insulating rolling bearing unit according to any one of Configurations 1 to 7, wherein the insulating washer is formed of insulating resin or insulating rubber.

[0026] By adopting this configuration, the annular protrusion of the insulating washer can be easily formed using a mold, which is low cost.

[0027] [Configuration 9] The insulated rolling bearing unit according to any one of Configurations 1 to 8, wherein the thickness of the insulating coating is set to 10 to 50 μm.

[0028] In the insulating rolling bearing unit of this invention, the insulating washer has an annular protrusion that radially surrounds the outer ring chamfered portion, so insulation between the inner periphery of the housing to which the outer ring is assembled and the outer ring chamfered portion can be achieved by the annular protrusion of the insulating washer, without relying on an insulating coating, thereby ensuring stable insulation performance between the housing to which the outer ring is assembled and the outer ring chamfered portion.

[0029] FIG. 10 is a cross-sectional view of an insulating rolling bearing unit according to a sixth embodiment of the present invention;

[0030] 1 shows an insulating rolling bearing unit according to a first embodiment of the present invention. This insulating rolling bearing unit has a rolling bearing 1 and an annular insulating washer 2.

[0031] The rolling bearing 1 has an outer ring 3, an inner ring 4 arranged coaxially radially inside the outer ring 3, a plurality of rolling elements 5 assembled at intervals circumferentially between the outer ring 3 and the inner ring 4, and a retainer 6 that maintains the circumferential spacing of the plurality of rolling elements 5.

[0032] The outer ring 3, inner ring 4, and rolling elements 5 are each made of steel. In this example, the rolling elements 5 are balls. The rolling elements 5 are radially sandwiched between an outer ring raceway groove 7 formed on the inner circumference of the outer ring 3 and an inner ring raceway groove 8 formed on the outer circumference of the inner ring 4. The outer ring raceway groove 7 and the inner ring raceway groove 8 are grooves whose cross sections perpendicular to the circumferential direction are arc-shaped. It is possible to use rolling elements other than balls as the rolling elements 5.

[0033] The outer ring 3 has an outer ring width surface 9 perpendicular to the axial direction, formed at the axial end on the insulating washer 2 side (left side in the figure), an outer peripheral cylindrical surface 10 whose outer diameter remains constant along the axial direction, and an outer ring chamfered portion 11 with an arc-shaped cross section formed between the outer peripheral cylindrical surface 10 and the outer ring width surface 9. The outer ring width surface 9 and the outer peripheral cylindrical surface 10 are connected via the outer ring chamfered portion 11.

[0034] As shown in Figure 2, the outer peripheral cylindrical surface 10 and the outer ring chamfered portion 11 are coated with an insulating coating 12. On the other hand, the outer ring width surface 9 is not coated with the insulating coating 12, and the steel material constituting the outer ring 3 is exposed.

[0035] The insulating coating 12 is made of resin. Examples of resins that can be used to form the insulating coating 12 include polyamide-imide resin, polyamide resin, polyimide resin, fluororesin, isocyanate resin, silicone resin, furan resin, butyral resin, elastomer resin, epoxy resin, phenolic resin, urea resin, amino resin, and acrylic resin. The insulating coating 12 can be formed by subjecting the outer peripheral cylindrical surface 10 and outer ring chamfered portion 11 of the outer ring 3 to a surface treatment, then applying a resin dissolved in a solvent, and baking the dried coating. The insulating coating 12 has a thickness of 10 to 50 μm and a withstand voltage of 0.01 kV / μm or greater.

[0036] The insulating washer 2 is provided axially adjacent to the outer ring 3. The insulating washer 2 has an annular plate portion 13 that faces the outer ring width surface 9 in the axial direction, and an annular protrusion 14 that is formed to protrude in the axial direction from the radial outer end of the annular plate portion 13 so as to surround the outer ring chamfered portion 11 from the radial outside.

[0037] The annular plate portion 13 is formed in a flat plate shape with a constant axial thickness along the radial direction. When viewed from the axial direction, the annular plate portion 13 has a circular ring shape that covers the outer ring width surface 9. The inner diameter of the annular plate portion 13 is smaller than the diameter of the radially inner end of the outer ring width surface 9.

[0038] The annular protrusion 14 has a tapered cross-sectional shape with its radial width gradually decreasing toward its tip. The outer periphery of the annular protrusion 14 is a cylindrical surface with an outer diameter equal to or smaller than the outer diameter of the insulating coating 12 that coats the outer peripheral cylindrical surface 10 of the outer ring 3, and the inner periphery of the annular protrusion 14 is a curved surface with a concave arc cross-section that fits into the outer ring chamfered portion 11. The annular plate portion 13 and the annular protrusion 14 of the insulating washer 2 are integrally formed from insulating resin made of a resin material to which fiber reinforcing materials such as glass fiber have been added.

[0039] As shown in Figure 2, this insulating rolling bearing unit can be used by being assembled to a housing 15. The housing 15 has a cylindrical inner peripheral fitting surface 16 that fits onto the outer peripheral cylindrical surface 10 of the outer ring 3, an axial end face 17 that extends radially inward from the axial end of the inner peripheral fitting surface 16, and an inner peripheral cylindrical surface 18 that extends from the radial inner end of the axial end face 17 to the side opposite the inner peripheral fitting surface 16 (to the left in the figure). The insulating washer 2 is assembled by abutting against the axial end face 17 of the housing 15. The inner diameter of the insulating washer 2 is set smaller than the inner diameter of the inner peripheral cylindrical surface 18 of the housing 15.

[0040] As shown in Figure 2, this insulated rolling bearing unit has an insulating washer 2 with an annular protrusion 14 that surrounds the outer ring chamfer 11 from the radial outside, so that insulation between the inner peripheral fitting surface 16 of the housing 15 and the outer ring chamfer 11 can be achieved by the annular protrusion 14 of the insulating washer 2, without relying on the insulating coating 12. This makes it possible to reliably ensure insulation performance between the housing 15 and the outer ring chamfer 11. Therefore, when mass-producing rolling bearings 1, it is not necessary to perform an insulation performance test (current test) to guarantee the insulating performance of the insulating coating 12 on the outer ring chamfer 11.

[0041] Furthermore, as shown in FIG. 1, the annular protrusion 14 of the insulating washer 2 has a tapered cross-sectional shape in which the radial width gradually decreases toward the tip. This makes it easy for the annular protrusion 14 of the insulating washer 2 to enter the radial gap between the inner fitting surface 16 of the housing 15 and the outer ring chamfered portion 11, and it is possible for the annular protrusion 14 of the insulating washer 2 to reliably surround the outer ring chamfered portion 11.

[0042] Furthermore, because the insulating washer 2 is made of insulating resin, the annular protrusion 14 of the insulating washer 2 can be easily formed using a mold, resulting in low cost. Here, the insulating washer 2 formed from insulating resin has been described as an example, but the insulating washer 2 having the shape shown in FIG. 1 may also be formed from insulating rubber. Even in this case, the annular protrusion 14 of the insulating washer 2 can be easily formed using a mold, resulting in low cost. When the insulating washer 2 is made of insulating rubber, the rigidity of the insulating washer 2 can be ensured by employing a configuration in which a core metal is embedded inside the insulating rubber.

[0043] 3 and 4 show a second embodiment of the present invention. The second embodiment differs from the first embodiment only in that the outer ring chamfer 11 is not coated with the insulating coating 12, but otherwise has the same configuration as the first embodiment. This makes it possible to reduce the area coated with the insulating coating 12 and reduce costs.

[0044] In this embodiment, if the insulating washer 2 is formed from insulating rubber, the insulating washer 2 is first assembled into the housing 15 (see Figure 4), and then when the rolling bearing 1 is assembled into the housing 15, the tip of the annular protrusion 14 formed from insulating rubber is pulled in between the inner fitting surface 16 of the housing 15 and the outer cylindrical surface 10 of the outer ring 3, thereby ensuring insulation between the inner fitting surface 16 of the housing 15 and the outer ring chamfered portion 11.

[0045] 5 and 6 show a third embodiment of the present invention. The parts corresponding to those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

[0046] The outer ring 3 has an outer ring width surface 9 perpendicular to the axial direction formed at the axial end on the insulating washer 2 side (left side in the figure), an outer peripheral cylindrical surface 10 with a constant outer diameter that does not change along the axial direction, an outer ring chamfered portion 11 with an arc-shaped cross section formed between the outer peripheral cylindrical surface 10 and the outer ring width surface 9, and a slightly inclined surface 19 with a linear cross section formed between the outer peripheral cylindrical surface 10 and the outer ring chamfered portion 11. The outer ring width surface 9 and the outer peripheral cylindrical surface 10 are connected to the outer ring chamfered portion 11 via the slightly inclined surface 19.

[0047] The slightly inclined surface 19 is formed in a cross-sectional linear shape inclined at an angle of 10° or less with respect to the outer peripheral cylindrical surface 10. The slightly inclined surface 19 is formed in a range of the outer periphery of the outer ring 3 that does not have a portion overlapping with the outer ring raceway groove 7 when viewed from the radial direction, or, even if there is an overlapping portion, at least in a range that does not have a portion overlapping with the osculating ellipse of the rolling element 5 and the outer ring raceway groove 7.

[0048] The contact ellipse is the elliptical surface contact portion formed between the rolling element 5 and the outer ring 3 when a load is applied between them, and its dimensions are determined from an equation based on Hertz's theory, based on the magnitude of the load acting between the rolling element 5 and the outer ring 3. When determining the dimensions of the contact ellipse, the basic static radial load rating can be used to determine the magnitude of the load acting between the rolling element 5 and the outer ring 3.

[0049] The outer peripheral cylindrical surface 10 and the slightly inclined surface 19 are coated with an insulating coating 12. Meanwhile, the outer ring chamfer 11 and the outer ring width surface 9 are not coated with the insulating coating 12, leaving surfaces where the steel material making up the outer ring 3 is exposed. Here, the portion of the insulating coating 12 that coats the slightly inclined surface 19, like the portion of the insulating coating 12 that coats the outer peripheral cylindrical surface 10, is coated on a surface with a small curvature, and therefore the coating thickness can be easily measured using an electromagnetic coating thickness meter or the like.

[0050] 6 , the annular protrusion 14 of the insulating washer 2 has at its tip an annular insertion portion 20 that is inserted into an annular gap on the radially outer side of the slightly inclined surface 19. In the figure, the insertion portion 20 is shown as being inserted to the deepest position of the annular gap between the inner peripheral fitting surface 16 of the housing 15 and the slightly inclined surface 19 on the outer periphery of the outer ring 3, but an insertion portion 20 that is inserted to a position partway in the axial direction of the annular gap between the inner peripheral fitting surface 16 of the housing 15 and the slightly inclined surface 19 on the outer periphery of the outer ring 3 may also be used.

[0051] As shown in Figure 6, in the insulating rolling bearing unit of this embodiment, the tip of the annular protrusion 14 of the insulating washer 2 and the insulating coating 12 coated on the slightly inclined surface 19 on the outer periphery of the outer ring 3 overlap radially, ensuring reliable radial insulation between the inner peripheral fitting surface 16 of the housing 15 and the outer ring chamfered portion 11.

[0052] Furthermore, as in the second embodiment, the outer ring chamfer 11 is not coated with the insulating coating 12, so the area coated with the insulating coating 12 can be reduced, resulting in lower costs. Other effects are the same as in the first embodiment.

[0053] 7 shows a fourth embodiment of the present invention. In the fourth embodiment, a second annular protrusion 21 is added to the insulating washer 2 of the third embodiment, but the other configuration is the same as that of the third embodiment. Therefore, parts corresponding to those of the third embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0054] The insulating washer 2 has a second annular protrusion 21 formed to protrude in the axial direction from the radially inner end of the annular plate portion 13. The second annular protrusion 21 is fitted onto the inner periphery of the outer ring 3.

[0055] When this configuration is adopted, the insulating washer 2 and the outer ring 3 can be positioned in the radial direction by fitting the second annular protrusion 21 into the inner periphery of the outer ring 3 .

[0056] 8 and 9 show a fifth embodiment of the present invention. The fifth embodiment is similar to the third embodiment except that an engaging claw portion 22 is added to the insulating washer 2 of the third embodiment. Therefore, parts corresponding to those of the third embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0057] An outer ring raceway groove 7 with which the rolling elements 5 roll and make contact, and an annular groove 23 extending circumferentially between the outer ring raceway groove 7 and the outer ring width surface 9 are formed on the inner periphery of the outer ring 3. The insulating washer 2 has engaging claws 22 formed to protrude in the axial direction from the radially inner end of the annular plate portion 13. A hook portion 24 protruding radially inward is formed at the tip of the engaging claw portion 22, and the hook portion 24 fits into the annular groove 23 on the inner periphery of the outer ring 3, thereby restricting axial movement of the insulating washer 2 away from the outer ring 3.

[0058] As shown in FIG. 9, the engaging claws 22 are provided at a plurality of locations (three locations in the figure) at regular intervals (120° intervals in the figure) in the circumferential direction.

[0059] As shown in Figure 8, in this embodiment, the insulating rolling bearing unit holds the insulating washer 2 on the outer ring 3 so that it does not move away from the outer ring width surface 9 due to the engagement between the engaging claw portion 22 and the annular groove 23, and the rolling bearing 1 and insulating washer 2 can be handled as an integrated assembly.

[0060] Furthermore, as shown in Figure 9, multiple engaging claws 22 are provided at intervals in the circumferential direction, and the engagement between the engaging claws 22 and the annular groove 23 makes it possible to position the insulating washer 2 and the outer ring 3 radially.

[0061] 10 and 11 show a sixth embodiment of the present invention. The sixth embodiment has the same basic configuration as the third embodiment, but differs in the material of the insulating washer 2. Portions corresponding to those in the third embodiment are given the same reference numerals and will not be described.

[0062] 11 , the insulating washer 2 has an annular plate portion 13 axially facing the outer ring width surface 9, and an annular protrusion 14 formed to protrude in the axial direction from the radial outer end of the annular plate portion 13 so as to surround the outer ring chamfered portion 11 from the radial outside. The annular protrusion 14 has a rectangular cross-sectional shape with a constant radial width along the axial direction. The insulating washer 2 is formed by coating the entire surface of the metal washer with an insulating coating 12.

[0063] The annular protrusion 14 of the insulating washer 2 has at its tip an annular insertion portion 20 that is inserted into an annular gap on the radially outer side of the slightly inclined surface 19. The insertion portion 20 is inserted to a position partway in the axial direction into the annular gap between the inner peripheral fitting surface 16 of the housing 15 and the slightly inclined surface 19 on the outer periphery of the outer ring 3.

[0064] As shown in Figure 11, in the insulating rolling bearing unit of this embodiment, the tip of the annular protrusion 14 of the insulating washer 2 and the insulating coating 12 coated on the slightly inclined surface 19 on the outer periphery of the outer ring 3 overlap radially, ensuring reliable radial insulation between the inner peripheral fitting surface 16 of the housing 15 and the outer ring chamfered portion 11.

[0065] 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.

[0066] REFERENCE SIGNS LIST 1 Rolling bearing 2 Insulating washer 3 Outer ring 4 Inner ring 5 Rolling element 7 Outer ring raceway groove 9 Outer ring width surface 10 Outer peripheral cylindrical surface 11 Outer ring chamfered portion 12 Insulating coating 13 Annular plate portion 14 Annular protrusion 19 Slightly inclined surface 20 Insertion portion 21 Second annular protrusion 22 Engagement claw portion 23 Annular groove

Claims

1. An insulated rolling bearing unit comprising: a rolling bearing (1) having an outer ring (3), an inner ring (4) disposed radially inside the outer ring (3), and a plurality of rolling elements (5) assembled between the outer ring (3) and the inner ring (4); and an annular insulating washer (2) disposed adjacent to the outer ring (3) in the axial direction, wherein the outer ring (3) has an outer ring width surface (9) perpendicular to the axial direction formed at the axial end on the insulating washer (2) side, an outer peripheral cylindrical surface (10) having a constant outer diameter along the axial direction, and an outer ring chamfered portion (11) formed between the outer peripheral cylindrical surface (10) and the outer ring width surface (9), and the outer peripheral cylindrical surface (10) is coated with an insulating coating (12), an insulating rolling bearing unit characterized in that the insulating washer (2) has an annular plate portion (13) axially opposed to the outer ring width surface (9), and an annular protrusion (14) formed protruding axially from the radial outer end of the annular plate portion (13) so as to surround the outer ring chamfer portion (11) from the radial outside.

2. The insulating rolling bearing unit according to claim 1, wherein the annular projection (14) has a tapered cross-sectional shape in which the radial width gradually decreases toward the tip.

3. An insulated rolling bearing unit as claimed in claim 1 or 2, wherein the outer ring (3) has a slightly inclined surface (19) having a linear cross section that is inclined at an angle of 10° or less with respect to the outer peripheral cylindrical surface (10) between the outer peripheral cylindrical surface (10) and the outer ring chamfered portion (11), the slightly inclined surface (19) is coated with the insulating coating (12), and the annular protrusion (14) has at its tip an insertion portion (20) that is inserted into an annular gap radially outward of the slightly inclined surface (19).

4. An insulated rolling bearing unit according to any one of claims 1 to 3, wherein the outer ring chamfer portion (11) is not coated with the insulating coating (12).

5. An insulating rolling bearing unit as described in any one of claims 1 to 4, wherein the insulating washer (2) further has a second annular protrusion (21) formed so as to protrude axially from the radial inner end of the annular plate portion (13), and the second annular protrusion (21) is fitted into the inner circumference of the outer ring (3).

6. An insulated rolling bearing unit as described in any one of claims 1 to 4, wherein an outer ring raceway groove (7) with which the rolling elements (5) roll and make contact, and an annular groove (23) extending circumferentially between the outer ring raceway groove (7) and the outer ring width face (9) are formed on the inner circumference of the outer ring (3), and the insulating washer (2) has an engaging claw portion (22) that engages with the annular groove (23).

7. An insulating rolling bearing unit according to claim 6, wherein a plurality of said engaging claw portions (22) are provided at intervals in the circumferential direction.

8. An insulating rolling bearing unit according to any one of claims 1 to 7, wherein the insulating washer (2) is made of insulating resin or insulating rubber.

9. An insulated rolling bearing unit according to any one of claims 1 to 8, wherein the thickness of the insulating coating (12) is set to 10 to 50 µm.

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