Bearing device with integrated electrical insulation, especially for an electric machine or motor

Abstract

The device comprises a bearing 10, which is provided with a first ring 12 and a second ring 14. The device comprises at least one insulating sleeve 26, which is attached to the second ring 14 and is provided with a bushing 28 and with an insulating insert 30. The insulating insert is attached 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 end faces 28c, 28d, which limit the axial length of the bushing. A first connecting chamfer 28e connects the first end face 28c of the bushing to the outer surface and is provided with a first concave radius connected to the outer surface while forming a sharp edge, with a second concave radius connected to the end face 28c while forming another sharp edge, and with a frustoconical surface extending between the first and second concave radii.

Description

Technical field of the invention

[0001] The present invention relates to the field of bearings, which are used in particular in electric motors, electrical machines and related devices. State of the art

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

[0003] In operation, when the shaft rotates, a difference in electrical potential can occur between the latter and the housing of the electric machine or motor, generating an electric current between the inner ring of the rolling bearing connected to the shaft and the outer ring connected to the housing.

[0004] The electric current flowing through the components of the rolling bearing can destroy these components, especially the rolling elements and raceways formed on the inner and outer rings. The electric shocks can also cause vibrations.

[0005] To eliminate these disadvantages, it is known to replace the bearing's rolling elements, which are made of the same steel as the inner and outer rings, with ceramic rolling elements. This type of bearing is commonly referred to as a "hybrid rolling bearing".

[0006] However, such hybrid roller bearings are relatively expensive.

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

[0008] The bore of the housing may be damaged while the bearing device is being attached to or removed from the housing.

[0009] The present invention aims to eliminate this disadvantage. Summary of the invention

[0010] The invention relates to a bearing device comprising a bearing provided with a first ring and a second ring which are rotatable relative to each other.

[0011] The device also includes at least one insulating sleeve attached to the second ring of the bearing. The insulating sleeve is provided with a bushing and an insulating insert, which is radially inserted between the second ring of the bearing and the bushing. The insulating insert is made of an electrically insulating material.

[0012] The bushing comprises a cylindrical outer surface and a cylindrical inner surface on the opposite side of the outer surface, which define the radial thickness of the bushing. The bushing also comprises first and second end faces, which define the axial length of the bushing.

[0013] The insulating insert is attached to the second ring of the bearing and to at least one of the outer and inner surfaces of the bushing.

[0014] According to a general characteristic, a first connecting chamfer connects the first end face of the bushing with the other surface of the outer and inner surfaces of the bushing.

[0015] The first connecting chamfer is provided with a first concave radius that is connected to the other surface of the socket while forming a sharp edge, with a second concave radius that is connected to the first end face while forming another sharp edge, and with a frustoconical surface that extends between the first and second concave radii.

[0016] This results in a bearing device with integrated electrical insulation, which is economical and easy to manufacture compared to conventional hybrid rolling bearings.

[0017] Furthermore, due to the presence of the first connecting chamfer with a blunt shape, the device is easy to install into the associated electric machine or motor without the risk of damaging the bore of the electric motor or machine.

[0018] Each sharp edge forms a change in slope between the first connecting chamfer and the other face of the bushing, or between the first connecting chamfer and the first end face of the bushing.

[0019] The frustoconical surface of the first connecting chamfer reduces the projecting nature 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, it is possible to provide different values.

[0022] Preferably, a second connecting chamfer connects the second end face of the bushing to the other face of the bushing.

[0023] In this case, the second connecting chamfer is advantageously provided with a first concave radius that is connected to the other surface of the socket while forming a sharp edge, with a second concave radius that is connected to the second end face while forming another sharp edge, and with a frustoconical surface that extends between the first and second concave radii.

[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 provide different values.

[0026] Advantageously, the bushing is made of metal. The bushing can be produced, for example, by pressing or machining.

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

[0028] If the insulating insert is made of a synthetic material or an elastomer material, this makes the device less sensitive to temperature fluctuations.

[0029] In one embodiment, the insulating insert covers the entire surface of the bushing. In this case, the insulating insert completely covers the surface of the bushing in both the axial and circumferential directions.

[0030] The term "axial direction" means the direction parallel to the axis of the bearing device.

[0031] The term "circumferential direction" means the direction that is perpendicular to both the axial direction and the radius of the bearing device, in other words the tangent to a circle whose center is on the axis of the bearing device.

[0032] According to a first embodiment, the bushing defines the outer surface of the device. In this case, the second ring is the outer ring of the bearing.

[0033] According to a second alternative embodiment, the bushing defines the inner surface of the 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 series of rolling elements arranged between the raceways of the first and second rings. The rolling elements may be made of metal.

[0035] The invention also relates to an electric motor comprising a housing, a shaft and at least one bearing device as defined above and mounted radially between the housing and the shaft.

[0036] The invention also relates to a method for manufacturing a bushing of a bearing device as defined above, comprising the following successive steps: - a step in the production of a bushing blank that gives it its basic geometry, - a heat treatment step to give the bushing blank the required hardness, - a step of radial grinding of the first end face of the bushing blank and a part of the second concave radius of the first connecting chamfer, which is adjacent to the first end face, and - a step of axial grinding of the other surface of the bushing blank and a part of the first concave radius of the first connecting chamfer adjacent to the other surface.

[0037] The term “radial direction” means the direction along a radius of the bearing device, i.e. any direction that intersects the axis of the bearing device and is perpendicular to that axis. Brief character description

[0038] The present invention will be better understood by considering the detailed description of an embodiment, which is presented as a complete non-limiting example and illustrated by the accompanying drawings, in which: [ Fig. 1] a half view, in axial section, of a bearing device according to an exemplary embodiment of the invention is, [ Fig. 2], [ Fig. 3] Detailed views of a bushing of the device Fig. 1 are, [ Fig. 4] a perspective view of the socket of the device made of Fig. 1 is, and [ Fig. 5], [ Fig. 6] Detailed views of the socket of the device Fig. 1 before and after the grinding step. Detailed description of the invention

[0039] The in Fig. The bearing device shown in Figure 1 comprises a bearing 10 provided with a first ring 12 and a second ring 14, which are rotatable relative to each other about the axis XX' of the bearing. In the exemplary embodiment shown, the first ring 12 is the inner ring of the bearing and the second ring 14 is the outer ring of the bearing.

[0040] The bearing device was designed so that it does not conduct electrical currents. The bearing device has integrated electrical insulation.

[0041] The inner ring 12 and the outer ring 14 of the bearing are concentric and extend axially along the axis XX' of the bearing. The inner ring 12 and the outer ring 14 are made of steel. The rings are solid.

[0042] In the illustrated exemplary embodiment, the bearing 10 also includes a series of rolling elements 16, in this case balls, which are inserted 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 to ensure uniform circumferential spacing of the rolling elements 16. The bearing 10 may also be equipped with seals or flange gaskets.

[0043] The inner ring 12 comprises a cylindrical bore 12a, a cylindrical axial outer surface 12b radially opposite the bore, and two opposing radial end faces (without reference numerals) that axially define 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.

[0044] The inner ring 12 also includes an inner raceway 18 for the rolling elements 16, which is formed on the outer surface 12b. The raceway 18 is directed radially towards the outside.

[0045] The outer ring 14 comprises a cylindrical, axial outer surface 14a, a cylindrical bore 14b radially on the opposite side of the outer surface 14a, and two opposing radial end faces 14c, 14d that axially delimit 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.

[0046] The outer ring 14 also includes an outer raceway 20 for the rolling elements 16, which is formed on the bore 14b. The raceway 20 is directed radially inwards.

[0047] In the illustrated exemplary embodiment, a groove 22 is formed on the end face 14d of the outer ring. The groove 22 is axially oriented towards the outside of the outer ring and is open. The groove 22 has a bottom that is axially offset towards the inside of the ring with respect to the end face 14d. The bottom of the groove 22 forms a shoulder. For the sake of simplicity of manufacture, the bottom of the groove 22 extends radially in this case. The groove 22 is annular in this case.

[0048] Similarly, a groove 24 is formed on the end face 14c of the outer ring. The groove 24 is axially oriented towards the outside of the outer ring and is open. The bottom of the groove 24 is offset axially towards the inside of the ring with respect to the end face 14c. The bottom of the groove 24 forms a shoulder. In this case, the bottom of the groove 24 extends radially. The groove 24 is annular in this case. The grooves 22 and 24 are mutually symmetrical with respect to a radial center plane of the outer ring. The grooves 22 and 24 axially delimit the outer surface 14a. Alternatively, it would be possible to omit the grooves 22 and 24.

[0049] The bearing assembly also includes an electrically insulating sleeve 26, which is attached to the outer ring 14. The insulating sleeve 26 is attached to the outer surface 14a of the outer ring 14. The insulating sleeve 26 is secured to the outer ring 14.

[0050] The insulating sleeve 26 comprises a bushing 28 and an insulating insert 30, which is inserted radially between the outer ring 14 and the bushing 28. In this case, the insulating insert 30 is overmolded onto the outer ring 14 and the bushing 28.

[0051] The bushing 28 has an annular shape. The bushing 28 of axis XX' extends axially. In this case, the bushing 28 is formed from a single piece. Alternatively, the bushing 28 could be made from several parts that abut one another, for example, two identical parts. The bushing 28 comprises a cylindrical, annular, axial outer surface 28a and a cylindrical, annular, axial bore 28b, which is radially located on the opposite side of the outer surface 28a. The bore 28b forms the inner surface of the bushing 28. The bore 28b is oriented radially inwards, i.e., towards the outer ring 14 and the insulating insert 30. The axis of the bore 28b is coaxial with the axis X-X'.

[0052] The bushing 28 also includes two opposing radial end faces 28c, 28d, which axially define the bore and the outer surface. The end faces 28c, 28d define the axial length of the bushing. The outer surface 28a and the bore 28b define the radial thickness of the bushing 28. The outer surface 28a of the bushing 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.

[0053] In the illustrated exemplary embodiment, the end faces 28c, 28d of the bushing are each coplanar with the end faces 14c, 14d of the outer ring. Alternatively, other arrangements could be provided. The bushing 28 could, for example, have a smaller or larger axial dimension and be axially recessed from the end faces 14c, 14d, or project from the faces.

[0054] As in the Fig. 2 and Fig. As shown more clearly in Figure 3, the socket 28 also includes first and second annular connecting chamfers 28e, 28f, which each connect the end faces 28c, 28d to the outer surface 28a.

[0055] The first connecting chamfer 28e is provided with a first concave radius 28e1, which is connected to the outer surface 28a, with a second concave radius 28e2, which is connected to the end surface 28c, and with a frustoconical surface 28e3, which extends between and connects the first and second concave radii.

[0056] The first concave radius 28e1 is directly connected to the outer surface 28a. The second concave radius 28e2 is directly connected to the end face 28c. In other words, for the first concave radius 28e1, there is no additional area between the first radius and the outer surface 28a, and for the second concave radius 28e2, there is no additional area between the second radius and the end face 28c. The frustoconical surface 28e3 is also directly connected to the first and second concave radii.

[0057] The first concave radius 28e1 is connected to the outer surface 28a, forming a sharp edge a1, and the second concave radius 28e2 is connected to the end surface 28c, forming another sharp edge a2.

[0058] In the illustrated exemplary embodiment, the first and second concave radii 28e1 and 28e2 are identical. Therefore, the values ​​of these radii are the same. Alternatively, the values ​​of the first and second radii 28e1 and 28e2 could be different.

[0059] In an identical manner to the first connecting chamfer 28e, the second connecting chamfer 28f is provided with a first concave radius 28f1, which is connected to the outer surface 28a, with a second concave radius 28f2, which is connected to the end face 28d, and with a frustoconical surface 28f3, which extends between the first and second concave radii and connects them.

[0060] The first concave radius 28f1 is directly connected to the outer surface 28a. The second concave radius 28f2 is directly connected to the end face 28d. In other words, for the first concave radius 28f1, there is no additional area between the first radius and the outer surface 28a, and for the second concave radius 28f2, there is no additional area between this second radius and the end face 28d. The frustoconical surface 28f3 is also directly connected to the first and second concave radii.

[0061] The first concave radius 28f1 is connected to the outer surface 28a, while forming a sharp edge a3, and the second concave radius 28f2 is connected to the end surface 28c, while forming another sharp edge a4.

[0062] In the illustrated exemplary embodiment, the first and second concave radii 28f1 and 28f2 are identical. Therefore, the values ​​of these radii are the same. Alternatively, the values ​​of the first and second radii 28f1 and 28f2 could be different.

[0063] Bushing 28 is made of metal. Preferably, bushing 28 is made of steel. Bushing 28 can be obtained from a sheet metal blank by cutting, pressing, and roll bending. Alternatively, bushing 28 can also be obtained from a tube, from a forged and / or rolled blank, or by stamping.

[0064] To manufacture the bushing 28, the following procedure is followed.

[0065] In a first step, a bushing blank is produced, which gives it its basic geometry with the rough shape of the outer surface 28a, the bore 28b, the end faces 28c, 28d and the connecting chamfers 28e, 28f.

[0066] In the Fig. 5 and Fig. Figure 6 shows the outer surface 28a, the connecting chamfers 28e, 28f, and the end faces 28c, 28d of the bushing blank as dashed lines. The centers of the first and second concave radii 28e1, 28e2 of the first connecting chamfer 28e are each marked with the reference symbol C. 28e1 , C 28e2 The midpoints of the first and second concave radii 28f1, 28f2 of the first connecting chamfer 28f each bear the reference symbols C 28f1 , C 28f2 .

[0067] In a subsequent second step, the bushing blank is heat-treated to give it the required hardness.

[0068] Then, in a subsequent third step, the end face 28c of the bushing blank and a portion of the second concave radius 28e2 of the first chamfer, adjacent to the end face 28c, and the end face 28d of the bushing blank and a portion of the second concave radius 28f2 of the second chamfer, adjacent to the end face 28d, are ground in the radial direction. The sharp edges a2 and a4 are formed during this step.

[0069] During this third step, the outer surface 28a of the bushing blank, a portion of the first concave radius 28e1 of the first chamfer adjacent to the outer surface 28a, and a portion of the first concave radius 28f1 of the second chamfer adjacent to the outer surface 28a are also ground in the axial direction. The sharp edges a1 and a3 are formed during this step.

[0070] These grinding steps blunt the first and second connecting chamfers 28e, 28f of the bushing. The sharp edge a1 is axially offset towards the outside, i.e., towards the end face 28c, with respect to the centers C. 28e1 , C 28e2 of the first and second radius 28e1, 28e2 of the first connecting chamfer.

[0071] The sharp edge a2 is offset radially towards the outside, i.e. in the direction of the outer surface 28a, with respect to the centers C 28e1 , C 28e2 of the first and second radius 28e1, 28e2 of the first connecting chamfer.

[0072] In the same way, the sharp edge a3 is axially oriented towards the outside, i.e. towards the end face 28d, with respect to the centers C 28f1 , C 28f2of the first and second radii 28f1, 28f2 of the second connecting chamfer offset, and the sharp edge a1 is radially offset towards the outside, i.e. towards the outer surface 28a, with respect to these centers.

[0073] After these grinding steps, the bushing 28 has its final shape and its final dimensions.

[0074] The insulating insert 30 is made of an electrically insulating material. The insulating insert 30 can be made, for example, of a synthetic material such as PEEK or PA46, or of an elastomeric material such as rubber.

[0075] The insulating insert 30 is inserted radially between the outer surface 14a of the outer ring and the bore 28b in the bushing. The insulating insert 30 covers the outer surface 14a of the outer ring. In this case, the insulating insert completely covers the outer surface 14a in both the axial and circumferential directions. The insulating insert 30 also covers the grooves 22 and 24 of the outer ring. The insulating insert 30 also covers the bore 28b in the bushing. In this case, the insulating insert 30 also completely covers the bore 28b in both the axial and circumferential directions.

[0076] As indicated above, the insulating insert 30 is overmolded onto the outer ring 14 of the bearing and the bushing 28 in this case. The insulating insert 30 is overmolded onto the outer surface 14a of the outer ring 14 and the bore 28b in the bushing 28.

[0077] The insulating insert 30 has an annular shape. The insulating insert 30 extends axially. The insulating insert 30 comprises a cylindrical, axial outer surface 30a, a cylindrical bore 30b radially opposite the outer surface 30a, and two opposing radial end faces 30c, 30d that axially delimit the bore and the outer surface. The radial end faces 30c, 30d delimit the axial length of the insulating insert 30. The outer surface 30a and the bore 30b delimit the radial thickness of the insulating insert 30. The outer surface 30a is in radial contact with the bore 28b in the bushing. 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.

[0078] In the exemplary embodiment shown, the surfaces 14c, 30c, 28c and 14d, 30d, 28d of the outer ring, the insulating insert and the bushing are each coplanar.

[0079] Alternatively, other arrangements are possible. For example, the insulating insert 30 could have a smaller axial dimension and be set back axially from surfaces 14c, 14d of the outer ring. Alternatively, the insulating insert 30 could have a larger axial dimension and project axially from surfaces 14c, 14d of the outer ring. In this case, the insulating insert 30 can at least partially cover these surfaces 14c, 14d. In one variant, the insulating insert 30 could at least partially cover surfaces 28c, 28d of the bushing.

[0080] Alternatively, or in combination, the bushing 28 could project axially from the insulating insert 30 with respect to the surfaces 30c and 30d, or it could be axially offset from the surfaces.

[0081] In the exemplary embodiments shown, the first ring 12 of the bearing is the inner ring and the second ring 14 is the outer ring to which the insulating insert 30 is attached.

[0082] Alternatively, a reverse arrangement can be provided in which the second ring 14, to which the insulating insert 30 is attached, is the inner ring. In this case, the insulating sleeve is located in the bore 12a in the inner ring. The insulating insert is then inserted radially between the bore 12a in the inner ring and the outer surface of the bushing. The insulating insert is attached to the inner ring and at least to the outer surface of the bushing. The bore in the bushing defines the bore in the bearing assembly.

[0083] In this case, the connecting chamfer or chamfers connect the end faces of the bushing to the bore.

[0084] In the exemplary embodiments described, the bearing of the device is provided with a single row of rolling elements. In one variant, the bearing can be provided with multiple rows of rolling elements. Furthermore, the rolling bearing can include rolling elements other than balls, for example, rollers. In another variant, the bearing can be a plain bearing without rolling elements.

Claims

[1] Bearing device comprising a bearing (10) having a first ring (12) and a second ring (14) rotatable relative to each other, and an insulating sleeve (26) attached to the second ring (14) of the bearing, and provided with a bushing (28) and an insulating insert (30) inserted radially between the second ring (14) and the bushing (28), and made of an electrically insulating material, wherein the bushing comprises a cylindrical outer surface (28a) and a cylindrical inner surface (28b) on the side opposite the outer surface, which define the radial thickness of the bushing, and first and second end faces (28c, 28d) which define the axial length of the bushing, wherein the insulating insert (30) is attached to the second ring (14) of the bearing and to at least one of the outer and inner surfaces of the bushing (28), characterized by, that a first connecting chamfer (28e) connects the first end face (28c) of the bushing with the other surface of the outer and inner surfaces of the bushing (28), wherein the first connecting chamfer (28e) is provided with a first concave radius (28e1) which is connected to the other surface of the bushing (28) while forming a sharp edge (a1), with a second concave radius (28e2) which is connected to the first end face (28c) while forming another sharp edge (a2), and with a frustoconical surface (28e3) which extends between the first and second concave radii (28e1, 28e2). [2] Device according to claim 1, wherein the first and second concave radii (28e1, 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 (28e1). [4] Device according to one of the preceding claims, wherein a second connecting chamfer (28f) connects the second end face (28d) of the bushing to the other face of the bushing (28), wherein the second connecting chamfer (28f) is provided with a first concave radius (28f1) which is connected to the other face of the bushing (28) while forming a sharp edge (a3), with a second concave radius (28f2) which is connected to the second end face (28d) while forming another sharp edge (a4), and with a frustoconical surface (28f3) which extends between the first and second concave radii (28f1, 28f2). [5] Device according to claim 4, wherein the first and second concave radii (28f1, 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 (28f1). [7] Device according to one of the preceding claims, wherein the bushing (28) is made of a metal material. [8] Device according to claim 7, wherein the bushing (28) is obtained by pressing or machining. [9] A method for manufacturing a bushing of a bearing device according to any of the preceding claims, comprising the following successive steps: - a step in the production of a bushing blank that gives it its basic geometry, - a heat treatment step to give the bushing blank the required hardness, - a step of radial grinding of the first end face (28c) of the bushing blank and part of the second concave radius (28e2) of the first connecting chamfer, which is adjacent to the first end face, and - a step of axial grinding of the other surface of the bushing blank and part of the first concave radius (28e1) of the first connecting chamfer adjacent to the 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, which is mounted radially between the housing and the shaft.

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