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

Abstract

[Integrated electrically insulated bearing device, particularly for electric motors or machines] The device includes a bearing 10 having a first ring 12 and a second ring 14. The device includes an insulating sleeve 26 mounted on the second ring 14 and having a bushing 28 and an insulating lining 30. The insulating lining is fixed to the second ring 14 and to at least one of the outer and inner surfaces of the bushing 28. The bushing 28 also includes first and second front faces 28c, 28d defining the axial length of said bushing.A first connecting chamfer 28e links the first front face 28c of the socket to the outer surface, and is provided with a first concave radius connecting to the outer surface by forming a sharp edge, a second concave radius connecting to the first front face 28c by forming another sharp edge, and a frustoconical surface extending between the first and second concave radii. 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] During the mounting of this bearing device inside the engine casing or during its removal, the bore of the casing may be damaged.

[0009] The present invention aims to remedy this drawback. Summary of the invention

[0010] 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.

[0011] The device further comprises at least one insulating sleeve mounted on the second bearing ring. The insulating sleeve is provided with a socket and a An insulating gasket is radially interposed between the second bearing ring and the bushing. The insulating gasket is made of electrically insulating material.

[0012] The sleeve comprises a cylindrical outer surface and a cylindrical 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.

[0013] The insulation lining is fixed to the second ring of the bearing and at least to one of the outer and inner surfaces of the bushing.

[0014] According to a general characteristic, a first connecting chamfer links the first front face of the socket to said other surface of the outer and inner surfaces of the socket.

[0015] The first connecting chamfer is provided with a first concave radius connecting to said other surface of the socket by forming a sharp edge, a second concave radius connecting to the first front face by forming another sharp edge, and a frustoconical surface extending between the first and second concave rays.

[0016] Thus, we have an economical integrated electrically insulated bearing device compared to conventional hybrid rolling bearings.

[0017] Moreover, the device is easy to assemble in the motor or associated electrical machine without risk of damage to the bore of the motor or electrical machine due to the presence of the first truncated chamfer for connection.

[0018] Each sharp edge forms a break in slope between the first connecting chamfer and said other surface of the socket, or between the first connecting chamfer and the first front face of the socket.

[0019] The frustoconical surface of the first connecting chamfer makes it possible to reduce the salient character of each of the sharp edges.

[0020] Preferably, the first and second concave radii of the first connecting chamfer have different centers.

[0021] The value of the second concave radius of the first connecting chamfer is equal to the value of the first concave radius. Alternatively, different values ​​may be used.

[0022] Preferably, a second connecting chamfer links the second front face of the socket to said other surface of the socket.

[0023] In this case, the second connecting chamfer advantageously has a first concave radius connecting to said other surface of the socket by forming a sharp edge, and a second concave radius connecting to the second face frontal by forming another sharp edge, and of a frustoconical surface extending between the first and second concave rays.

[0024] Preferably, the first and second concave radii of the second connecting chamfer have different centers.

[0025] The value of the second concave radius of the second connecting chamfer is equal to the value of the first concave radius. Alternatively, it is possible to specify different values.

[0026] Advantageously, the sleeve is made of metallic material. The sleeve can, for example, be obtained by stamping or machining.

[0027] Preferably, the insulating gasket is overmolded onto the second bearing ring and at least onto said bushing surface. Alternatively, the insulating gasket can be fixed by any other suitable means, for example by bonding.

[0028] If the insulation lining is made of synthetic material or elastomeric material, it makes the device less sensitive to temperature variations.

[0029] 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.

[0030] By "axial direction" is meant the direction parallel to the axis of the bearing device.

[0031] By “circumferential direction”, we mean the direction which is perpendicular to both to 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The invention further relates to a method for manufacturing a bushing for a bearing device as defined above, comprising the following successive steps:

[0037] - a step in producing a rough socket giving it its geometry of base,

[0038] - a heat treatment step to give the socket blank hardness required

[0039] - a radial grinding step of the first front face of the blank of socket and a portion of the second concave radius of the first connecting chamfer that is adjacent to the first front face, and

[0040] - an axial grinding step of said other surface of the socket blank and of a portion of the first concave radius of the first connecting chamfer which is adjacent to said other surface.

[0041] By "radial direction" is meant the direction along a radius of the bearing device, that is to say any direction intersecting the axis of the bearing device and perpendicular to this axis. Brief description of the figures

[0042] The present invention will be better understood upon study of the detailed description of an embodiment, taken by way of non-limiting example and illustrated by the accompanying drawings, in which:

[0043] [Fig. 1] is a half-view in axial cross-section of a bearing device according to an exemplary embodiment of the invention,

[0044] [Fig.2]

[0045] [Fig.3] are detailed views of a socket of the device in [Fig.1],

[0046] [Fig.4] is a perspective view of the socket of the device in [Fig.1], and

[0047] [Fig.5]

[0048] [Fig.6] are detailed views of the device's socket [Fig.1] before and after rectification steps. 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 regular circumferential spacing rolling elements 16. Bearing 10 can also 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 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. The bore 12a forms the inner surface of the inner ring.

[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 two opposing radial front faces 14c, 14d axially defining the bore. The outer surface 14a and the bore 14b define the radial thickness of the outer ring 14. The bore 14b has a stepped shape.

[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] In the illustrated embodiment, a groove 22 is formed on the front face 14d of the outer ring. The groove 22 is oriented and axially open towards the outside of the outer ring. The groove 22 has a bottom that is axially offset towards the inside of the ring relative to the front face 14d. The bottom of the groove 22 forms a shoulder. The bottom of the groove 22 extends radially here for manufacturing simplicity. The groove 22 is annular.

[0058] Similarly, a groove 24 is formed on the front face 14c of the outer ring. The groove 24 is oriented and axially open towards the outside of the outer ring. The groove 24 has a bottom that is axially offset towards the inside of the ring relative to the front face 14c. The bottom of the groove 24 forms a shoulder. The bottom of the groove 24 extends radially here. The groove 24 is annular here. The grooves 22, 24 are symmetrical to each other with respect to a median radial plane of the outer ring. The grooves 22, 24 axially delimit the outer surface 14a. Alternatively, it might be possible to omit the grooves 22, 24.

[0059] 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.

[0060] 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 here overmolded on the outer ring 14 and on the sleeve 28.

[0061] The sleeve 28 is annular in shape. The sleeve 28, with axis X-X', extends axially. The sleeve 28 is here made in one piece. Alternatively, the sleeve 28 could be made in several pieces supported against each other, for example, two identical pieces. 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 outer ring 14 and the insulating gasket 30. The axis of the bore 28b is coaxial with the axis X-X'.

[0062] The sleeve 28 also includes two opposing radial front faces 28c, 28d axially defining the bore and the outer surface. The front faces 28c, 28d define the axial length of the sleeve. The outer surface 28a and the bore 28b define the radial thickness of the sleeve 28. The outer surface 28a of the sleeve defines the outer surface of the bearing device 10. In other words, the outer surface 28a defines the outer diameter of the bearing device 10.

[0063] In the illustrated embodiment, the front faces 28c, 28d of the sleeve are respectively coplanar with the front faces 14c, 14d of the outer ring. Alternatively, other arrangements could be provided. For example, the sleeve 28 could have a smaller or larger axial dimension and remain axially recessed from the faces 14c, 14d of the outer ring, or protrude from said faces.

[0064] As more visibly illustrated in figures 2 and 3, the sleeve 28 further includes first and second annular connecting chamfers 28e, 28f linking respectively the front faces 28c, 28d to the outer surface 28a.

[0065] The first connecting chamfer 28e is provided with a first concave radius 28ei connecting to the outer surface 28a, a second concave radius 28e2 connecting to the front face 28c, and a frustoconical surface 28e3 extending between the first and second concave rays and connecting them.

[0066] The first concave ray 28ei connects directly to the outer surface 28a. The second concave ray 28e2 connects directly to the front face 28c. In other words, for the first concave ray 28eb there is no additional surface between this first ray and the outer surface 28a, and for the second concave ray 28e2, there is no additional surface between this second ray and the front face 28c. The frustoconical surface 28e3 also connects directly to the first and second concave rays.

[0067] The first concave ray 28eise connects to the outer surface 28a by forming a sharp edge ai and the second concave ray 28e2se connects to the front face 28c by forming another sharp edge a2.

[0068] In the illustrated embodiment, the first and second concave radii 28ei and 28e2 are identical. Thus, the values ​​of these radii are equal. Alternatively, the values ​​of the first and second concave radii 28ei and 28e2 could be different.

[0069] In the same way as the first connecting chamfer 28e, the second connecting chamfer 28f is provided with a first concave radius 28fi connecting to the outer surface 28a, a second concave radius 28f2 connecting to the front face 28d, and a frustoconical surface 28f3 extending between the first and second concave rays and connecting them.

[0070] The first concave ray 28f1 connects directly to the outer surface 28a. The second concave ray 28f2 connects directly to the front face 28d. In other words, for the first concave ray 28f1, there is no additional surface between this first ray and the outer surface 28a, and for the second concave ray 28f2, there is no additional surface between this second ray and the front face 28d. The frustoconical surface 28f3 also connects directly to the first and second concave rays.

[0071] The first concave ray 28f connects to the outer surface 28a by forming a sharp edge a3 and the second concave ray 28f2 connects to the front face 28c by forming another sharp edge 34.

[0072] In the illustrated embodiment, the first and second concave radii 28f1 and 28f2 are identical. Thus, the values ​​of these radii are equal. Alternatively, the values ​​of the first and second concave radii 28f1 and 28f2 could be different.

[0073] The bushing 28 is made of metallic material. Preferably, the bushing 28 is made of steel. The bushing 28 can be obtained from a sheet metal blank by cutting, stamping, and rolling. Alternatively, the bushing 28 can be obtained from a tube or from forged and / or rolled blanks, or from stamping.

[0074] To manufacture the socket 28, the following procedure is used.

[0075] In a first step, a rough socket is produced giving it its basic geometry with the rough shape of the outer surface 28a, the bore 28b, the front faces 28c, 28d and the connecting chamfers 28e, 28f.

[0076] In Figures 5 and 6, the outer surface 28a, the connecting chamfers 28e, 28f, and the front faces 28c, 28d of the socket blank are shown in dashed lines. The centers of the first and second radii 28eb and 28e2 of the first concave connecting chamfer 28e are respectively referenced C28e1 and C28e2. The centers of the first and second radii 28fb and 28f2 of the second concave connecting chamfer 28f are respectively referenced C28f1 and C28f2.

[0077] Next, in a second successive step, the blank of the socket is heat-treated to give it the required hardness.

[0078] Then, in a third successive step, the front face 28c of the socket blank and a portion of the second concave radius 28e2 of the first chamfer adjacent to this front face 28c are rectified in the radial direction, as well as the front face 28d of the socket blank and a portion of the second concave radius 28f2 of the second chamfer adjacent to this front face 28d. The sharp edges a2 and a4 are formed during this step.

[0079] During this third step, the outer surface 28a of the socket blank is also rectified along the axial direction, as well as a portion of the first concave radius 28e1 of the first chamfer that is adjacent to the outer surface 28a, and a portion of the first concave radius 28fi of the second chamfer that is adjacent to this outer surface 28a. The sharp edges ai and a3 are formed during this step.

[0080] With the rectification steps, the first and second chamfers 28e, 28f of the sleeve connection are truncated. The sharp edge ai is axially offset outwards, i.e. on the side of the front face 28c, relative to the centers C28ei, C28e2 of the first and second radii 28eb 28e2 of the first connecting chamfer.

[0081] The sharp edge a2 is radially offset outwards, i.e. on the side of the outer surface 28a, relative to the centers C28ei, C28e2 of the first and second radii 28eb 28e2 of the first connecting chamfer.

[0082] Similarly, the sharp edge a3 is axially offset outwards, i.e. on the side of the front face 28d, with respect to the centers C28fi, C28f2 of the first and second radii 28fb 28f2 of the second connecting chamfer, and the sharp edge a4 is radially offset outwards, i.e. on the side of the outer surface 28a, with respect to these centers.

[0083] After these rectification steps, the socket 28 has its final shape and dimensions.

[0084] 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.

[0085] 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 in both the axial and circumferential directions. The insulating gasket 30 also covers the grooves 22, 24 of the inner ring. The insulating gasket 30 also covers the bore 28b of the sleeve. The insulating gasket 30 completely covers the bore 28b in both the axial and circumferential directions.

[0086] As previously stated, the insulating packing 30 is here overmolded onto the outer ring 14 of the bearing and onto the bushing 28. The insulating packing 30 is overmolded onto the outer surface 14a of the outer ring 14 and onto the bore 28b of the bushing 28.

[0087] The insulating sleeve 30 is annular in shape. The insulating sleeve 30 extends axially. The insulating sleeve 30 comprises a cylindrical axial outer surface 30a, a cylindrical bore 30b radially opposed to the outer surface 30a, and two opposing radial front faces 30c, 30d axially delimiting the bore and the outer surface. The radial front faces 30c, 30d define the axial length of the insulating sleeve 30. The outer surface 30a and the bore 30b define the radial thickness of the insulating sleeve 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 of the outer ring, and with the grooves 22, 24. The bore 30b has a stepped shape.

[0088] In the illustrated embodiment, the faces 14c, 30c, 28c and 14d, 30d, 28d of the outer ring, the insulating lining and the sleeve are respectively coplanar.

[0089] Alternatively, other arrangements are possible. For example, the insulating gasket 30 could have a reduced axial dimension and remain axially recessed from the faces 14c, 14d of the outer ring. Alternatively, the insulating gasket 30 could have an increased axial dimension and extend axially beyond the faces 14c, 14d of the outer ring. In this case, the insulating gasket 30 can at least partially cover these faces 14c, 14d. As a variant, the insulating gasket 30 could at least partially cover the faces 28c, 28d of the sleeve.

[0090] In another alternative or in combination, the sleeve 28 could extend axially in projection from the insulation lining 30 relative to the faces 30c and 30d, or remain axially recessed from these faces.

[0091] 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 fixed is the outer ring.

[0092] Alternatively, an inverted arrangement may be provided in which the second ring 14, to which the insulating sleeve 30 is attached, 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 interposed radially between the bore 12a of the inner ring and the outer surface of the sleeve. The insulating sleeve is fixed to the inner ring and at least to the outer surface of the sleeve. The bore of the sleeve defines the bore of the bearing device. The connecting chamfer(s) in this case connect the front faces of the sleeve to the bore.

[0093] 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

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, and an insulating sleeve (26) mounted on the second ring (14) of the bearing and having a bushing (28) and an insulating lining (30) interposed radially between the second ring (14) and the bushing (28) and made of electrically insulating material, the bushing comprising a cylindrical outer surface (28a) and a cylindrical 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 insulating lining (30) being fixed on the second ring (14) of the bearing and at least on one of the outer and inner surfaces of the bushing (28),characterized in that a first connecting chamfer (28e) links the first front face (28c) of the socket to said other surface of the outer and inner surfaces of the socket (28), the first connecting chamfer (28e) being provided with a first concave radius (28ei) connecting to said other surface of the socket (28) by forming a sharp edge (aj), a second concave radius (28e2) connecting to the first front face (28c) by forming another sharp edge (a2), and a frustoconical surface (28e3) extending between the first and second concave radii (28eb 28e2).

2. Device according to claim 1, wherein the first and second concave radii (28eb 28e2) of the first connecting chamfer have different centers.

3. Device according to claim 1 or 2, wherein the value of the second concave radius (28e2) of the first connecting chamfer is equal to the value of the first concave radius (28ei).

4. A device according to any one of the preceding claims, wherein a second connecting chamfer (28f) connects the second front face (28d) of the sleeve to said other surface of the sleeve (28), the second connecting chamfer (28f) having a first concave radius (28f1) connecting to said other surface of the sleeve (28) by forming a sharp edge (a3), a second concave radius (28f2) connecting to the second front face (28d) by forming another sharp edge (a4), and a surface frustoconical (28f3) extending between the first and second concave rays (28fb 28f2).

5. Device according to claim 4, wherein the first and second concave radii (28fb 28f2) of the second connecting chamfer have different centers.

6. Device according to claim 4 or 5, wherein the value of the second concave radius (28f2) of the second connecting chamfer is equal to the value of the first concave radius (28fi).

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

8. Device according to claim 7, wherein the sleeve (28) is obtained by stamping or machining.

9. A method for manufacturing a bushing of a bearing device according to any one of the preceding claims comprising the following successive steps: - a step of producing a bushing blank giving it its basic geometry, - a heat treatment step to give the bushing blank the required hardness, - a radial grinding step of the first front face (28c) of the bushing blank and of a part of the second concave radius (28e2) of the first connecting chamfer which is adjacent to the first front face, and - an axial grinding step of said other surface of the bushing blank and of a part of the first concave radius (28ei) of the first connecting chamfer which is adjacent to said other surface.

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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