Bearing device with integrated electrical insulation, particularly for electric motors or machines

Abstract

[Bearing device with integrated electrical insulation, particularly for electric motors or machines] The bearing device comprises a bearing 10 having a first ring 12 and a second ring 14 capable of rotating relative to each other. The device includes at least one insulating sleeve 26 mounted on the second ring and having a bushing 28 and an insulating gasket 30. The insulating gasket 30 is overmolded onto the second ring and at least onto one of the outer and inner surfaces of the bushing. The bushing and the second ring are respectively provided with first and second front faces 28c, 28d and 14c, 14d defining their axial length. The first front face 14c of the second ring is axially offset inwards relative to the first front face 28c of the sleeve and the second front face 14d of the second ring is axially offset inwards relative to the second front face 28d of the sleeve.Reference: Figure 1.

Description

Title of the invention: Bearing device with integrated electrical insulation, particularly for electric motors or machines. Technical field of the invention

[0001] The present invention relates to the field of bearings used in particular in electric motors, electrical machines and associated equipment. Prior art

[0002] In an electric motor or machine, at least one roller bearing is mounted between the housing of the motor or electric machine and the rotating shaft in order to support this shaft.

[0003] During operation when the shaft is rotating, an electrical potential difference may appear between it and the housing of the motor or electrical machine, which generates an electric current between the inner ring of the bearing which is attached to the shaft, and the outer ring attached to the housing.

[0004] The electric current passing through the components of the rolling bearing can damage these components, in particular the rolling elements and the raceways formed on the inner and outer rings. Electrical discharges can also generate vibrations.

[0005] To overcome these drawbacks, it is known to replace the bearing's rolling elements, made of the same steel as the inner and outer rings, with rolling elements made of ceramic. This is generally referred to as a hybrid bearing.

[0006] However, such a hybrid bearing is relatively expensive.

[0007] To remedy the aforementioned disadvantages, it is also known to equip the outer ring of the bearing with an insulating sleeve provided with a bushing and an insulating lining made of electrically insulating material and interposed radially between the outer ring and the bushing.

[0008] In order to achieve the fixing of the insulation lining on the outer ring and on the sleeve without additional element or special machining on the outer ring, it is possible to overmold the insulation lining.

[0009] However, with such a solution, a relative separation of the insulation lining and the outer ring may occur during operation.

[0010] The present invention therefore aims to remedy the aforementioned drawbacks by proposing a bearing device of simple and economical design. Summary of the invention

[0011] The invention relates to a bearing device comprising a bearing provided with a first ring and a second ring capable of rotating relative to each other.

[0012] The device further comprises at least one insulating sleeve mounted on the second bearing ring. The insulating sleeve is provided with a bushing and an insulating gasket interposed radially between the second bearing ring and the bushing. The insulating gasket is made of electrically insulating material.

[0013] The sleeve comprises an outer surface and an inner surface opposite the outer surface, which define the radial thickness of said sleeve. The sleeve also comprises first and second front faces defining the axial length of said sleeve.

[0014] The second ring comprises an outer surface and an inner surface opposite the outer surface, which define the radial thickness of said second ring. The second ring also comprises first and second front faces defining the axial length of said second ring.

[0015] The insulation lining is overmolded at least on one of the outer and inner surfaces of the second ring and at least on one of the outer and inner surfaces of the sleeve.

[0016] The first front face of the second ring and the first front face of the sleeve are located axially on one side with respect to a median radial plane of the device. The second front face of the second ring and the second front face of the sleeve are located axially on a second side with respect to said median radial plane.

[0017] According to a general characteristic, the first front face of the second ring is axially offset towards the inside of the device relative to the first front face of the socket.

[0018] According to another general feature, the second front face of the second ring is axially offset towards the inside of the device relative to the second front face of the socket.

[0019] According to yet another general feature, the insulation lining is further overmolded onto the first and second front faces of the second ring.

[0020] Overmolding the insulating lining onto these first and second front faces ensures a secure bond with the second ring. The risk of relative displacement between the insulating lining and the second ring in the axial direction is avoided, particularly during temperature variations. "Axial direction" refers to the direction parallel to the axis of the bearing assembly.

[0021] Furthermore, having the first and second front faces of the second ring axially recessed respectively with respect to the first and second front faces of the sleeve makes it possible to reduce the machining time of the The device is designed so that only the front faces of the sleeve are ground. The overall weight of the device is also reduced due to the shorter axial length of the second ring compared to that of the sleeve.

[0022] The insulation lining is provided with first and second front faces delimiting its axial length of said lining.

[0023] According to a first design, at least one of the first and second front faces of the socket can be axially flush with one of said front faces of the insulation lining.

[0024] According to a second design, each of the first and second front faces of the socket is axially flush with one of said front faces of the insulation lining.

[0025] Alternatively, one or both of the front faces of the socket can be axially offset inwards or outwards relative to the associated front face of the insulation lining.

[0026] The first ring comprises first and second front faces delimiting the axial length of said first ring.

[0027] In a particular embodiment, the first and second front faces of the first ring may be respectively coplanar with the first and second front faces of the sleeve.

[0028] In one embodiment, said surface of the socket includes at least one protrusion which extends radially outward from the side of the second ring.

[0029] In another embodiment, the sleeve is monobloc and includes an axial portion delimiting said surface of the sleeve on which the insulation lining is overmolded, and first and second collars extending the axial portion radially on the side of the second ring.

[0030] By "one-piece socket," it is meant that the socket is made in one piece. The socket is made in one piece.

[0031] The insulating lining is further overmolded onto an inner face of each of the first and second flanges of the sleeve. The second flange of the sleeve may extend radially beyond the surface of the second ring onto which the insulating lining is overmolded. The first flange of the sleeve may remain radially recessed from the outer surface of the second ring.

[0032] In another embodiment, the sleeve is made of at least two separate parts. These two parts jointly define an axial portion delimiting the surface of the sleeve onto which the insulating lining is overmolded, and each includes a flange extending the axial portion radially on the side of the second ring. The insulating lining is further overmolded onto an inner face of each flange of each of the two sleeve parts.

[0033] According to a particular design, said surface of the socket is provided with at least one groove extending in the circumferential direction and within which extends a rib for attaching the insulation lining of complementary shape.

[0034] Thus, the axial attachment of the insulation lining to the socket is further increased.

[0035] By "circumferential direction" is meant the direction which is perpendicular to both the axial direction and to a radius of the bearing device, in other words, tangent to a circle whose center is on the axis of the bearing device.

[0036] If the insulation lining is made of synthetic material or elastomer material, it makes the device less sensitive to temperature variations.

[0037] In a particular embodiment, the bushing is made of metallic material. The bushing can thus be easily machined to a predetermined radial tolerance. Advantageously, the bushing is obtained from a sheet metal blank by cutting, stamping, and rolling.

[0038] In one embodiment, said insulating lining covers the entire surface of said socket. In this case, said insulating lining completely covers said surface of the socket in the axial direction and in the circumferential direction.

[0039] According to a first conception, the sleeve delimits the outer surface of said device. In this case, the second ring is the outer ring of the bearing.

[0040] According to a second alternative design, the sleeve defines the inner surface of said device. In this case, the second ring is the inner ring of the bearing.

[0041] In a particular embodiment, the bearing comprises at least one row of rolling elements arranged between raceways of the first and second rings. The rolling elements may be made of metallic material.

[0042] The invention also relates to an electric motor comprising a casing, a shaft and at least one bearing device as defined above and mounted radially between the casing and the shaft. Brief description of the figures

[0043] The present invention will be better understood upon study of the detailed description of embodiments, taken by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0044] [Fig-1] is a half axial cross-sectional view of a bearing device according to an embodiment of the invention, and

[0045] [Fig.2]

[0046] [Fig.3]

[0047] [Fig.4]

[0048] [Fig.5] are half-views in axial section of bearing devices according to other embodiments of the invention. Detailed description of the invention

[0049] The bearing device illustrated in [Fig. 1] comprises a bearing 10 provided with a first ring 12 and a second ring 14 which are able to rotate relative to each other about the axis X-X' of the bearing. In the illustrated embodiment, the first ring 12 is the inner ring of the bearing and the second ring 14 is the outer ring.

[0050] The bearing device is designed so as not to conduct electric currents. The bearing device has integrated electrical insulation.

[0051] The inner ring 12 and outer ring 14 of the bearing are concentric and extend axially along the X-X' axis of the bearing. The inner ring 12 and outer ring 14 are made of steel. The rings are of the solid type.

[0052] In the illustrated embodiment, the bearing 10 also includes a row of rolling elements 16, here balls, interposed radially between the inner ring 12 and the outer ring 14. The rolling elements 16 are made of steel. The bearing 10 also includes a cage 17 for maintaining the regular circumferential spacing of the rolling elements 16. The bearing 10 can further be equipped with seals or sealing flanges.

[0053] The inner ring 12 comprises a cylindrical bore 12a, an axial cylindrical outer surface 12b radially opposed to the bore, and opposing radial first and second front faces 12c, 12d axially delimiting the bore and the outer surface. The bore 12a and the outer surface 12b define the radial thickness of the inner ring 12. The bore 12a forms the inner surface of the inner ring. The first and second front faces 12c, 12d define the axial length of the inner ring 12.

[0054] The inner ring 12 further includes an inner raceway 18 for the rolling elements 16 which is formed on the outer surface 12b. The raceway 18 is directed radially outwards.

[0055] The outer ring 14 comprises a cylindrical axial outer surface 14a, a cylindrical bore 14b radially opposed to the outer surface 14a, and opposing radial first and second faces 14c, 14d axially delimiting the bore 14b and the outer surface 14a. The outer surface 14a and the bore 14b define the radial thickness of the outer ring 14. The first and second faces 14c, 14d define the axial length of the outer ring 14.

[0056] The outer ring 14 further includes an outer raceway 20 for the rolling elements 16 which is formed on the bore 14b. The raceway 20 is directed radially inwards.

[0057] The bearing device also includes an electrical insulation sleeve 26 mounted on the outer ring 14. The insulation sleeve 26 is mounted on the outer surface 14a of the outer ring 14. The insulation sleeve 26 is integral with the outer ring 14.

[0058] The insulation sleeve 26 includes a sleeve 28 and an insulation packing 30 interposed radially between the outer ring 14 and the sleeve 28. The insulation packing 30 is overmolded on the outer ring 14 and on the sleeve 28.

[0059] The bushing 28 is annular in shape. The bushing 28 is made from a single piece. The bushing 28 is here made in one piece. Preferably, the bushing 28 is made of steel. The bushing 28 can advantageously be obtained from a tube or from forged and / or rolled blanks, or even from stamping.

[0060] The sleeve 28 comprises an axial annular cylindrical outer surface 28a, and an axial annular cylindrical bore 28b radially opposed to the outer surface 28a. The bore 28b forms the inner surface of the sleeve 28. The bore 28b is oriented radially inwards, i.e. towards the side of the outer ring 14 and the insulating gasket 30. The axis 25 of the bore 28b is coaxial with the axis X-X'.

[0061] The outer surface 28a and the bore 28b define the radial thickness of the bushing 28. The outer surface 28a of the bushing forms the outer surface of the bearing device 10. In other words, the outer surface 28a defines the outer diameter of the bearing device 10.

[0062] The sleeve 28 also includes opposing radial first and second front faces 28c, 28d axially delimiting the bore and the outer surface. The front faces 28c, 28d define the axial length of the sleeve.

[0063] The front faces 14c, 28c of the outer ring and the sleeve are located axially on one side with respect to a median radial plane P of the device, and the front faces 14d, 28d of the outer ring and the sleeve are located axially on a second side with respect to said median radial plane P, which is opposite to the first side. The median radial plane P passes here through the center of the rolling elements 16.

[0064] The front face 14c of the outer ring is axially offset inwards relative to the front face 28c of the sleeve. The front face 14d of the outer ring is axially offset inwards relative to the front face 28d of the sleeve. In other words, the front faces 14c, 14d of the outer ring are axially recessed relative to the front faces 28c, 28d of the sleeve. The axial dimension of the outer ring 14 is smaller than the axial dimension of the sleeve 28.

[0065] The front face 14c of the outer ring is axially offset inwards relative to the front face 12c of the inner ring. The front face 14d of the outer ring is axially offset inwards relative to the front face 12d of the inner ring.

[0066] The insulating gasket 30 is made of electrically insulating material. The insulating gasket 30 can, for example, be made of a synthetic material, such as PEEK or PA46, or be made of an elastomeric material, for example rubber.

[0067] The insulating gasket 30 is radially interposed between the outer surface 14a of the outer ring and the bore 28b of the sleeve. The insulating gasket 30 covers the outer surface 14a of the outer ring. The insulating gasket 30 completely covers the outer surface 14a of the outer ring in both the axial and circumferential directions. The insulating gasket 30 also covers the front faces 14c, 14d of the outer ring.

[0068] The insulating gasket 30 still covers the bore 28b of the sleeve. The insulating gasket 30 also completely covers the bore 28b here, considering both the axial and circumferential directions.

[0069] The insulating gasket 30 is annular in shape. The insulating gasket 30 extends axially. The insulating gasket 30 comprises a cylindrical axial outer surface 30a, a cylindrical bore 30b radially opposed to the outer surface 30a, and opposing radial first and second front faces 30c, 30d axially delimiting the bore and the outer surface. The radial front faces 30c, 30d axially delimit the insulating gasket 30. The outer surface 30a and the bore 30b define the radial thickness of the insulating gasket 30. The outer surface 30a is in radial contact with the bore 28b of the sleeve. The bore 30b is in radial contact with the outer surface 14a and with the front faces 14c, 14d of the outer ring. The 30b bore has a stepped shape.

[0070] The front face 14c of the outer ring is axially offset inwards relative to the front face 30c of the insulating gasket. The front face 14d of the outer ring is axially offset inwards relative to the front face 30d of the insulating gasket.

[0071] In the illustrated embodiment, the faces 30c, 28c and 30d, 28d of the insulating gasket and the socket are respectively coplanar. Alternatively, other arrangements are possible. For example, the socket 28 could extend axially outward from the insulating gasket 30 relative to the faces 30c and 30d, or remain axially recessed from these faces.

[0072] In the illustrated embodiment, the faces 12c, 28c and 12d, 28d of the inner ring and the sleeve are respectively coplanar. Alternatively, other arrangements are possible. For example, the sleeve 28 could extend axially protruding from faces 12c and 12d of the inner ring, or remaining axially recessed from these faces.

[0073] To manufacture the bearing device, the following procedure is used.

[0074] In a first step, the bushing 28 and the outer ring 14 of the bearing are mounted inside a mold which is intended for overmolding the insulation lining 30.

[0075] Next, in the second step, the insulation lining 30 is overmolded both onto the outer ring 14 and onto the sleeve 28.

[0076] Then, in a third successive step, the unit assembly formed by the outer ring 14, the sleeve 28 and the insulating lining 30 is extracted from the mold.

[0077] Next, in a fourth step, the front faces 28c, 28d of the bushing are ground. During this step, the outer surface 28a of the bushing and the raceway 20 of the outer ring can also be ground.

[0078] Finally, in a fifth step, the unit assembly formed by the outer ring 14, the bushing 28 and the insulation lining 30 is assembled with the row of rolling elements 16, the cage 17 and the inner ring 12.

[0079] The embodiment illustrated in [Fig.2], in which the identical elements bear the same references, differs from the first example in that the bore 28b of the sleeve includes a first protrusion 32 which extends inward, i.e. inward toward the lining 30. The protrusion 27 extends inward relative to the bore 32. The protrusion 32 extends radially.

[0080] The protrusion 32 is located at one axial end of the bore 28b of the sleeve. The protrusion 32 extends radially inward from the front face 28c of the sleeve. The outer face of the protrusion 32 is coplanar with the front face 28c.

[0081] In the illustrated embodiment, the bore 28b of the sleeve also includes, at its other axial end, a second protrusion 34 that extends inward, i.e., in the direction of the insulating gasket 30. The protrusion 34 extends inward relative to the bore 28b. The protrusion 34 extends radially. The protrusion 34 extends radially inward from the front face 28d of the sleeve. The outer face of the protrusion 34 is coplanar with the front face 28d.

[0082] The embodiment illustrated in [Fig. 3], in which the identical elements bear the same reference numerals, differs from the first example in that the bushing 28 is obtained from a sheet metal blank by cutting, stamping, and rolling. The bushing 28 is made as a single piece.

[0083] In this example, the sleeve 32 comprises an axial portion 36a, and first and second radial annular flanges 36b, 36c each extending radially inwards the axial portion. Each collar 36b, 36c extends radially. Each collar 36b, 36c extends an axial end of the axial portion 36a. In the illustrated embodiment, the collars 36b, 36c are annular. Alternatively, at least one of the collars 36b, 36c could be in the form of sectors spaced from each other in the circumferential direction.

[0084] The front face 28c of the socket is delimited by the collar 36b, and the front face 28d is delimited by the collar 36c. More precisely, the front face 28c is delimited by the outer face of the collar 36b, and the front face 28d is delimited by the outer face of the collar 36c. The insulating gasket 30 also covers the inner face of each collar 36b, 36c of the socket. The inner face and the outer face axially opposite the inner face of each collar 36b and 36c define the axial thickness of said collar. For each collar 36b and 36c, the inner face is oriented axially towards the inside of the device, and the outer face is oriented axially towards the outside of the device. The insulation trim 30 also covers the free end of each collar 36b, 36c of the socket.

[0085] The collar 36b of the sleeve extends radially beyond the outer surface 14a of the outer ring, i.e. radially projecting inwards relative to the outer surface 14a. In other words, the free end of the collar 36b is offset radially inwards relative to the outer surface 14a of the outer ring.

[0086] The flange 36c of the sleeve remains radially recessed from the outer surface 14a of the outer ring. In other words, the free end of the flange 36b is radially offset outwards relative to the outer surface 14a of the outer ring. The flanges 36b and 36c remain axially distant from the outer ring 14.

[0087] The embodiment illustrated in [Fig. 4], in which the identical elements bear the same reference numerals, differs from the previous example primarily in that the bushing 28 is made up of two separate parts 38, 40. These two separate parts 38, 40 form half-flanges which are axially supported against each other. In the illustrated embodiment, the parts 38, 40 of the bushing are identical and symmetrical with respect to the median radial plane P of the device in order to reduce manufacturing costs. Alternatively, it is of course possible to provide for non-symmetrical parts 38, 40. In another variant, it could be possible to provide for the bushing 28 to be made up of more than two parts. Preferably, the parts 38, 40 of the bushing 28 are made of steel. The parts 38, 40 can advantageously be obtained from a sheet metal blank by cutting, stamping, and rolling. Each Part 38, 40 of the socket delimits part of the axial portion 36a and includes one of the collars 36b, 36c.

[0088] In the illustrated embodiment, the radial collars 36b, 36c of the sleeve extend radially beyond the outer surface 14a of the outer ring.

[0089] The bore of the axial portion 36a of the sleeve is provided with two axially spaced grooves 42, 44 extending circumferentially around the axis 25 of the sleeve bore. Each groove 42, 44 is oriented radially towards the outer ring 14, i.e., radially inwards. Groove 42 is formed on the portion 38 of the sleeve and groove 44 is formed on the portion 40.

[0090] In the illustrated embodiment, each groove 42, 44 is annular. Alternatively, at least one of the two grooves 42, 44 could not extend over 360°, or could be formed by a succession of turns extending circumferentially and spaced from each other in the circumferential direction.

[0091] Each groove 42, 44 is delimited in the axial direction by two opposing lateral sides which have a straight profile in axial section and are connected to each other by an axial bottom. Alternatively, it is possible to provide other shapes, for example grooves having here in cross-section a shape of an arc of a circle oriented inwards.

[0092] The insulation lining 30 also includes two ribs 46, 48 extending radially outwards from the outer surface 30a and each housed within one of the grooves 42, 44 of the sleeve. The rib 46, 48 is complementary in shape to the associated groove 42, 44. Each rib 46, 48 projects beyond the outer surface 30a of the insulation lining. Each rib 46, 48 is formed on the outer surface 30a during the overmolding of the insulation lining 30.

[0093] The embodiment illustrated in [Fig.5], in which the identical elements bear the same references, differs from the previous example mainly in that the outer ring 14 has an increased axial dimension.

[0094] The axial dimension of the outer ring 14 remains smaller than the axial dimension of the sleeve 28. The front face 14c of the outer ring remains axially offset inwards relative to the front face 28c of the sleeve. The front face 14d of the outer ring remains axially offset inwards relative to the front face 28d of the sleeve.

[0095] In the illustrated embodiment, a groove 50 is formed on the front face 14d of the outer ring. The groove 50 is oriented and axially open towards the outside of the outer ring. The groove 50 has a bottom that is axially offset towards the inside of the ring relative to the rest of the front face 14d. The bottom of the groove 50 forms a shoulder. The bottom of the groove 50 extends radially here for ease of manufacturing. The groove 50 is annular here. The collar 36b of the socket extends partially into the groove 50, remaining clear of the outer ring 14.

[0096] Similarly, a groove 52 is formed on the front face 14c of the outer ring. The groove 52 is oriented and axially open towards the outside of the outer ring. The groove 52 has a bottom that is axially offset towards the inside of the ring relative to the rest of the front face 14c. The bottom of the groove 52 forms a shoulder. The bottom of the groove 52 extends radially here. The groove 52 is annular here. The collar 36c of the sleeve extends partially into the groove 52 while remaining at a distance from the outer ring 14. The grooves 50, 52 are symmetrical to each other with respect to a median radial plane of the outer ring. The grooves 50, 52 axially delimit the outer surface 14a. The insulating gasket 30 covers the grooves 50, 52 of the inner ring.

[0097] In the illustrated embodiments, the first ring 12 of the bearing is the inner ring and the second ring 14 on which the insulation packing 30 is overmolded is the outer ring.

[0098] Alternatively, an inverted arrangement may be provided in which the second ring 14, onto which the insulating sleeve 30 is overmolded, is the inner ring. In this case, the insulating sleeve is located in the bore 12a of the inner ring. The insulating sleeve is then radially interposed between the bore 12a of the inner ring and the outer surface of the bushing. The insulating sleeve is overmolded at least on the inner surface of the inner ring and at least on the outer surface of the bushing. The bore of the bushing defines the bore of the bearing device.

[0099] In the described embodiments, the bearing of the device is provided with a single row of rolling elements. Alternatively, the bearing may be provided with several rows of rolling elements. Furthermore, the rolling bearing may include other types of rolling elements than balls, for example, rollers. In another embodiment, the bearing may be a sliding bearing without rolling elements.

Claims

1.

2. Demands Bearing device comprising a bearing (10) having a first ring (12) and a second ring (14) capable of rotating relative to each other, and an insulating sleeve (26) mounted on the second ring (14) of the bearing and having a bushing (28) and an insulating gasket (30) interposed radially between the second ring (14) and the bushing (28) and made of electrically insulating material, the bushing comprising an outer surface (28a) and an inner surface (28b) opposite the outer surface and which define the radial thickness of said bushing, and first and second front faces (28c, 28d) defining the axial length of said bushing, the second ring (14) comprising an outer surface (14a) and an inner surface (14b) opposite the outer surface and which define the radial thickness of said second ring, and first and second front faces (14c, 14d) defining the axial length of said second ring,the insulating lining (30) being overmolded at least on one of the outer and inner surfaces of the second ring (14) and at least on one of the outer and inner surfaces of the sleeve (28), the first front face (14c) of the second ring and the first front face (28c) of the sleeve being located axially on a first side with respect to a median radial plane (P) of the device, and the second front face (14d) of the second ring and the second front face (28d) of the sleeve being located axially on a second side with respect to said median radial plane (P), characterized in that the first front face (14c) of the second ring is axially offset inwards with respect to the first front face (28c) of the sleeve and the second front face (14d) of the second ring is axially offset inwards with respect to the second front face (28d) of the sleeve,and in that the insulating lining (30) is further overmolded onto the first and second front faces (14c, 14d) of the second ring. A device according to claim 1, wherein the insulating lining (30) is provided with first and second front faces (30c, 30d) defining the axial length of said lining, at least one of the first and second front faces (28c, 28d) of the sleeve axially flush with one of the said front faces (30c, 30d) of the insulation lining.

3. Device according to claim 2, wherein each of the first and second front faces (28c, 28d) of the socket is axially flush with one of said front faces (30c, 30d) of the insulation lining.

4. Device according to any one of the preceding claims, wherein the first ring (12) comprises first and second front faces (12c, 12d) delimiting the axial length of said first ring which are respectively coplanar with the first and second front faces (28c, 28d) of the sleeve.

5. Device according to any one of the preceding claims, wherein said surface of the sleeve (28) comprises at least one protrusion (32, 34) which extends radially outward from the side of the second ring (14).

6. A device according to any one of claims 1 to 4, wherein the sleeve (28) is monobloc and comprises an axial portion (36a) delimiting said surface of the sleeve on which the insulating lining (30) is overmolded, and first and second flanges (36b, 36c) extending the axial portion radially on the side of the second ring (14), the insulating lining (30) being further overmolded on an inner face of each of the first and second flanges (36b, 36c), the second flange (36c) of the sleeve extending radially beyond said surface of the second ring (14) on which the insulating lining (30) is overmolded and the first flange (36b) of the sleeve remaining radially recessed from said outer surface of the second ring.

7. Device according to any one of claims 1 to 4, wherein the sleeve (28) is made in at least two separate parts (38, 40), said two parts jointly delimiting an axial portion (36a) delimiting said surface of the sleeve on which the insulating lining (30) is overmolded and each comprising a collar (36b, 36c) extending the axial portion radially on the side of the second ring (14), the insulating lining (30) being further overmolded on an inner face of each collar (36b, 36c).

8. Device according to any one of the preceding claims, wherein the socket (28) is made of metallic material.

9. Device according to any one of the preceding claims, wherein the insulating lining (30) is made of synthetic material or elastomeric material.

10. Electric motor comprising a housing, a shaft and at least one bearing device according to any one of claims 1 to 8 mounted radially between the housing and the shaft.

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