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] This 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 22 mounted on the second ring 14 of the bearing and having a bushing 24 and an insulating lining 26 overmolded onto the second ring 14 and made of electrically insulating material. The bushing comprises a first axial flange 24a and a second axial flange 24b connected by a central radial web 24c. The insulating lining 26 encloses at least the second axial flange 24b, the first axial flange 24a being radially offset from the insulating lining 26 on the side opposite the bearing 10. Reference: Figure 3

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. Damaged components can cause 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] The present invention therefore aims to remedy the aforementioned drawbacks by proposing a bearing device of simple and economical design. Summary of the invention

[0008] 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.

[0009] According to a general characteristic, the device further comprises at least one insulation sleeve mounted on the second ring of the bearing.

[0010] The insulation sleeve is provided with a bushing and an insulating lining overmolded onto the second ring. The insulating lining is made of electrically insulating material.

[0011] According to another general characteristic, the sleeve comprises a first axial base and a second axial base connected by a radial central web.

[0012] According to another general characteristic, the insulating lining encases at least the second axial base, the first axial base being radially offset relative to the insulation lining on the side opposite the bearing.

[0013] Thus, an economical integrated electrically insulated bearing device is available compared to conventional hybrid rolling bearings. Furthermore, the device is easy to manufacture and assemble in the associated motor or electrical machine.

[0014] Furthermore, the insulating seal is not exposed to impacts due to its radial arrangement between the second bearing ring and the first axial flange of the bushing. In addition, if the insulating seal is made of a synthetic or polymer material, it makes the device less sensitive to temperature variations. The encapsulation of at least the second axial flange of the bushing by the insulating seal prevents relative displacement between the bushing and the insulating seal, at least in the axial and circumferential directions, particularly during temperature variations.

[0015] With this design, the insulating seal is attached to the second ring and the bushing without any additional components or special machining on the second bearing ring for mounting the insulating seal. It is therefore possible to use a bearing with standard first and second rings. This reduces the cost of the device.

[0016] Preferably, the second axial flange of the sleeve comprises at least one protrusion extending radially towards the bearing. This configuration further limits the risk of relative circumferential displacements between the sleeve and the insulating lining.

[0017] Advantageously, the second axial base of the socket comprises a plurality of protrusions spaced from each other in the circumferential direction so that the second axial base has a wavy shape in the circumferential direction.

[0018] The protrusion(s) can be formed by plastic deformation of the sleeve. This further facilitates obtaining a low-cost bearing device.

[0019] Preferably, the sleeve is made in two parts axially supported against each other, each part comprising a first axial portion and a second axial portion connected by a third central radial portion, the first and second axial portions, and the third central radial portion forming respectively the first axial flange, the second axial flange and the central radial web.

[0020] Advantageously, the two parts of the sleeve are symmetrical with respect to a radial plane of the device. This configuration further facilitates obtaining a low-cost device since the two parts of the sleeve are identical to each other.

[0021] Advantageously, the second bearing ring comprises a cylindrical axial surface provided with at least one notch inside which extends a projection of complementary shape of the insulation packing. This configuration further limits the risk of relative movement between the second bearing ring and the insulation packing.

[0022] In a particular embodiment, the bushing is made of metallic material. Preferably, the bushing is made of steel. Such a bushing can be easily machined, if necessary, to a predetermined tolerance and exhibits structural strength characteristics that promote good durability.

[0023] In a particular embodiment, the insulation lining is made of a synthetic material, such as PEEK or PA46, or of a polymer material. Such an insulation lining has structural strength characteristics that promote good durability.

[0024] 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 and the first ring is the inner ring.

[0025] 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 and the first ring is the outer ring.

[0026] 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

[0027] The present invention will be better understood upon study of the detailed description of embodiments, taken by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0028] [Fig. 1] is a cross-sectional view of a bearing device according to an exemplary embodiment of the invention,

[0029] [Fig.2] is a cross-sectional view along axis II-II of [Fig. 1]

[0030] [Fig.3] is a half-sectional view along axis III-III of [Fig.2],

[0031] [Fig.4] is a half-view in section along axis IV-IV of [Fig.2] which corresponds to a detailed view of [Fig. 1], and

[0032] [Fig. 5] is a perspective view of part of a bushing of the bearing device figures 1 to 4. Detailed description of the invention

[0033] The bearing device illustrated in Figures 1 to 4 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.

[0034] As will be described in more detail later, the bearing device is designed so as not to conduct electric currents. The bearing device has integrated electrical insulation.

[0035] 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 rings 12 and 14 are made of steel and are of the solid type.

[0036] 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.

[0037] The inner ring 12 comprises a cylindrical bore 12a, an axial cylindrical outer surface 12b radially opposed to the bore, and two opposing radial front faces (not referenced) 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.

[0038] 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.

[0039] The outer ring 14 comprises a cylindrical axial outer surface 14a, a cylindrical bore 14b radially opposed to the outer surface 14a, and two opposing radial front faces 14c, 14d axially delimiting the bore and the outer surface. The outer surface 14a and the bore 14b define the radial thickness of the outer ring 14.

[0040] The outer ring 14 further includes an external raceway 20 for the rolling elements 16 which is formed on the bore 14b. The raceway 20 is directed radially inwards.

[0041] The bearing device also includes an electrical insulation sleeve 22 mounted on the outer ring 14. The insulation sleeve 22 is mounted on the outer surface 14a of the outer ring 14. The insulation sleeve 22 is integral with the outer ring 14.

[0042] The insulating sleeve 22 comprises a bushing 24 and an insulating gasket 26 overmolded onto the outer ring 14 and made of electrically insulating material. The insulating gasket 26 is integral with the outer ring 14 and the bushing 24.

[0043] The sleeve 24 comprises a first axial flange 24a and a second axial flange 24b connected by a central radial web 24c. In the embodiment example illustrated, the first axial sole 24a forms an outer sole and the second axial sole 24b forms an inner sole.

[0044] The outer sole 24a radially surrounds the inner sole 24b. The outer sole 24a comprises an outer face 28 which delimits the outer surface of the sleeve 24. The inner sole 24b comprises an inner face 29 which delimits the inner surface of the sleeve 24. The radial web 24c extends between the outer face 28 and the inner face 29, connecting said faces.

[0045] The outer face 28 and the inner face 29 define the radial thickness of the sleeve 24. The outer surface of the sleeve defines the outer surface of the bearing device 10. In other words, the outer surface of the sleeve 24 defines the outer diameter of the bearing device 10.

[0046] As will be described in more detail later, in the illustrated embodiment example, the socket 24 is made in two parts axially supported against each other.

[0047] The bushing 24 is advantageously made of metallic material. Thus, the outer surface 24a of the bushing can be easily machined, if necessary, to a predetermined tolerance. Preferably, the bushing 24 is made of steel. The bushing 24 can be obtained from a sheet metal blank by shallow or deep drawing, including a blank cutting operation. Alternatively, the bushing 24 can be obtained from a tube or from forged and / or rolled and / or sintered blanks.

[0048] The insulating gasket 26 is made of electrically insulating material. The insulating gasket 26 can, for example, be made of synthetic material, such as PEEK or PA46, or of polymer material.

[0049] The insulating gasket 26 surrounds the inner flange 24b of the sleeve. A portion of the insulating gasket 26 is thus radially interposed between the outer surface 14a of the outer ring and the outer flange 24a of the sleeve 24. The insulating gasket 26 covers the outer surface 14a of the outer ring 14. The insulating gasket 26 here completely covers the outer surface 14a. The insulating gasket 26 also covers the inner face 29 of the sleeve 24. The insulating gasket 26 here also completely covers the inner face 29. The insulating gasket 26 also covers an outer face 30 of the inner flange 24b of the sleeve 24. The insulating gasket 26 here also completely covers the outer face 30. In the illustrated example, the insulating gasket 26 also surrounds a portion of the radial web 24c.Alternatively, the insulating lining 26 could enclose only the inner flange 24b of the sleeve. The outer flange 24a of the sleeve is offset from the insulating lining 26 radially outwards, i.e. on the side opposite the bearing 10.

[0050] The insulation trim 26 is annular in shape. The insulation trim 26 extends axially. The insulating gasket 26 comprises a cylindrical axial outer surface 26a, an axial inner surface 26b radially opposed to the outer surface 26a, and two opposing radial front faces 26c, 26d axially delimiting the inner surface 26b and the outer surface 26a. The outer surface 26a and the inner surface 26b define the radial thickness of the insulating gasket 26. The outer surface 26a is here radially offset outwards relative to the outer face 30 of the inner base 24b of the sleeve 24. The inner surface 26b is in radial contact with the outer surface 14a of the outer ring 14.

[0051] In the illustrated embodiment, the insulation lining 26 covers at least partially the front faces 14c and 14d. The faces 26c and 26d are respectively axially offset outwards relative to the faces 14c and 14d.

[0052] Alternatively, other arrangements are possible. For example, the insulating gasket 26 could have a reduced radial dimension and remain radially recessed from the faces 14c, 14d of the outer ring. Alternatively, the faces 14c, 26c and 14d, 26d could be coplanar, respectively.

[0053] Preferably, the axial surface 14a of the outer ring 14 is provided with at least one notch 14e inside which extends a projection 26e of complementary shape to the insulation lining and formed during the overmolding of the latter.

[0054] As more clearly illustrated in Figures 2 and 5, the inner sole 24b comprises a plurality of protrusions 32 spaced circumferentially from one another and extending radially inward. The inner sole 24b has a corrugated shape in the circumferential direction. The protrusions 32 extend radially inward on the side of the bearing 10 and are encased by the insulating lining 26.

[0055] The protrusions 32 are formed from the outer face 30 of the inner sole 24b by local material pushing. The protrusions 32 are therefore formed by plastic deformation of the sleeve 24.

[0056] The prominences 32 are identical here and extend over an angular sector of approximately 30°. As an indication, it is possible to provide for prominences 32 extending over a different angular sector, for example between 15° and 45°.

[0057] In the illustrated embodiment, the protrusions 32 are spaced regularly from one another in the circumferential direction. Alternatively, a non-regular circumferential spacing could be provided. In the illustrated embodiment, there are six protrusions 32. Alternatively, a different number of protrusions could be provided.

[0058] As previously stated, in the illustrated embodiment, the sleeve 24 is made in two parts 34, 36 axially supported against each other, each part comprising an outer axial portion 38a and an inner axial portion 38b connected by a central radial portion 38c. The outer and inner axial portions and the central radial portion form respectively the outer axial flange 24a, the inner axial flange 24b and the radial web 24c. Alternatively, the sleeve 24 could be made in one piece.

[0059] Preferably, the two parts 34, 36 of the bushing 24 are symmetrical with respect to a radial plane R of the bearing device.

[0060] In the illustrated embodiment, the insulating gasket 26 is overmolded onto the outer ring 14 of the bearing and onto the bushing 24. The insulating gasket 26 is overmolded onto the outer surface 14a of the outer ring 14 and onto the inner flange 24b of the bushing 24. The projections 26e of the insulating gasket are formed during the overmolding process. The protrusions 32 of the bushing extend into the electrically insulating material of the insulating gasket 26. The inner flange 24b and the protrusions 32 are completely embedded within the electrically insulating material of the insulating gasket 26.

[0061] To manufacture the bearing device, the following procedure is used.

[0062] In a first step, the bearing 10 and the bushing 24 equipped with the protrusions 32 are mounted inside a mold which is intended for overmolding the insulating lining 26. In this position mounted inside the mold, the bushing 24 is radially away from the outer ring 14 of the bearing.

[0063] Then, in a second successive step, the insulation lining 26 is overmolded both onto the outer ring 14 of the bearing and onto the bushing 24.

[0064] Finally, the bearing device, which is in the form of a unit assembly, is extracted from the mold.

[0065] As previously stated, in the illustrated embodiment, the first ring 12 of the bearing is the inner ring, and the second ring 14, to which the insulating sleeve 22 is attached, is the outer ring. Alternatively, an inverted arrangement is possible in which the second ring 14, to which the insulating sleeve is attached, is the inner ring, and the first ring 12 of the bearing is the outer ring. In this case, the insulating sleeve is mounted in the bore of the inner ring. The insulating lining is then overmolded onto the bore of the inner ring and onto the outer flange of the bushing, which forms the second flange of said bushing. In this case, the inner flange of the bushing is offset radially inward relative to the insulating lining 26, i.e., on the side opposite the bearing 10. The bore of the bushing defines the bore of the bearing assembly.

[0066] In the described embodiments, the device's bearing 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 comprise other types of rolling elements than balls, for example, rollers. In a Another variant is that the bearing can be a sliding bearing without rolling elements.

Claims

Demands

1. Bearing device comprising a bearing (10) having a first ring (12) and a second ring (14) capable of rotating relative to each other, characterized in that the device comprises at least one insulation sleeve (22) mounted on the second ring (14) of the bearing and having a bushing (24) and an insulation lining (26) overmolded on the second ring (14) and made of electrical insulating material, the bushing (24) comprising a first axial flange (24a) and a second axial flange (24b) connected by a central radial web (24c), the insulation lining enveloping at least said second axial flange (24b), the first axial flange (24a) being radially offset relative to the insulation lining (26) on the side opposite the bearing (10).

2. Device according to claim 1, wherein the second axial base (24b) of the sleeve comprises at least one protrusion (32) extending radially in projection towards the bearing (10).

3. Device according to claim 2, wherein the second axial sole (24b) of the sleeve comprises a plurality of protrusions (32) spaced from each other in the circumferential direction so that the second axial sole (24b) has a wavy shape in the circumferential direction.

4. Device according to any one of the preceding claims, wherein the sleeve (24) is made in two parts (34, 36) axially supported against each other, each part comprising a first axial portion (38a) and a second axial portion (38b) connected by a third central radial portion (38c), the first and second axial portions, and the third central radial portion forming respectively the first axial flange (24a), the second axial flange (24b) and the central radial web (24c).

5. Device according to claim 4, wherein the two parts (34, 36) of the socket (24) are symmetrical with respect to a radial plane (R) of said device.

6. Device according to any one of the preceding claims, wherein the second ring (14) of the bearing comprises a cylindrical axial surface (14a) provided with at least one notch (14e) within which extends a projection (26e) of complementary shape to the insulation lining.

7. Device according to any one of the preceding claims, wherein the socket (24) is made of metallic material.

8. Device according to any one of the preceding claims, wherein the insulation lining (26) is made of synthetic material.

9. Device according to any one of the preceding claims, wherein the second ring (14) is the outer ring of the bearing and the first ring (12) is the inner ring.

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

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