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

Abstract

The bearing device comprises a bearing 10, which is provided with a first ring 12 and a second ring 14, which are rotatable relative to each other. The device comprises at least one insulating sleeve 26, which is attached to the second ring of the bearing and is provided with a one-piece bushing 28 and with an insulating insert 30, which is made of an electrically insulating material. The insulating insert 30 is overmolded on the second ring 14 of the bearing and on at least one of the outer and inner surfaces of the bushing. The bushing 28 comprises an axial section 32a, which limits the area of ​​the bushing on which the insulating insert 30 is overmolded, and first and second flanges 32b, 32c, which extend the axial section radially in the direction of the second ring 14, the radial dimension of the second flange 32c being larger than that of the first flange 32b.

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 different 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] To attach the insulating insert to the outer ring and the bushing without additional components or special machining of the outer ring, it is possible to overmold the insulating insert.

[0009] However, with such a solution, a relative separation of the insulating insert and the bushing can occur during operation.

[0010] The present invention therefore aims to overcome the aforementioned disadvantages by providing a storage device with a 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 which are rotatable relative to each other.

[0012] The device also includes an insulating sleeve attached to the second ring of the bearing. The insulating sleeve is provided with a one-piece bushing and an insulating insert that is radially inserted between the second ring of the bearing and the bushing. The insulating insert is made of an electrically insulating material.

[0013] The term "one-piece bushing" means that the bushing is manufactured integrally. The bushing can be manufactured as a single part, or alternatively as several parts that are joined together.

[0014] In other words, the socket forms a single, unified whole.

[0015] The bushing comprises an outer surface and an inner surface on the opposite side of the outer surface, which limit the radial thickness of the bushing.

[0016] The insulating insert is overmolded onto the second ring of the bearing and onto at least one of the outer and inner surfaces of the bushing.

[0017] According to a general characteristic, the bushing comprises an axial section that limits the area of ​​the bushing on which the insulating insert is overmolded, and first and second flanges that extend the axial section radially towards the second ring.

[0018] According to another general characteristic, the insulating insert is also overmolded onto an inner surface of the first and second flanges.

[0019] According to another general characteristic, the radial dimension of the second flange is larger than the radial dimension of the first flange of the bushing.

[0020] Manufacturing the bushing with flanges allows for a secure connection with the insulating insert. This avoids the risk of axial movement between the insulating insert and the bushing, particularly during temperature fluctuations.

[0021] The term "axial direction" means the direction parallel to the axis of the bearing device.

[0022] Providing flanges with different radial dimensions also makes it possible to have a bushing that has good mechanical strength on the side of the large flange, while on the side of the small flange, the axial fastening of the second ring, or the bearing as a whole, is easily made possible radially on the inner surface of the bushing or radially on the outer surface of the bushing.

[0023] This results in a bearing device with integrated electrical insulation, which is economical and easy to manufacture compared to conventional hybrid rolling bearings.

[0024] Preferably, the second flange of the bushing extends radially beyond an outer surface or inner surface of the second ring on which the insulating insert is overmolded.

[0025] With this measure, the portion of the insulating insert located axially between the second ring and the second flange of the bushing is not subjected to shear stresses when significant axial loads are applied to the device, which is mounted in the housing of the electric machine or motor in conjunction with the second flange, which abuts a shoulder of the housing. This is because, in this case, compressive stresses are exerted on this part of the insulating insert. This increases the reliability of the device.

[0026] Preferably, the first flange of the bushing is set back radially from the outer or inner surface of the second ring. This allows the axial fastening of the second ring, or the bearing as a whole, relative to the bushing to be achieved by a simple axial thrust.

[0027] A first groove can be formed on a first end face of the second ring and a second groove can be formed on a second end face of the second ring, wherein the first and second grooves axially limit the outer surface or inner surface of the second ring.

[0028] The first flange of the bushing can be radially spaced from the first groove, and the second flange can extend partially into the second groove.

[0029] The insulating insert can be provided with two end faces that limit its axial length.

[0030] According to a first embodiment, at least one of the first and second flanges of the bushing is axially flush with one of the end faces of the insulating insert.

[0031] According to a second embodiment, each of the first and second flanges of the bushing is axially flush with one of the end faces of the insulating insert.

[0032] Alternatively, one or each flange of the bushing may be axially offset in the direction of the inside or in the direction of the outside with respect to the associated end face of the insulating insert.

[0033] According to a specific embodiment, the surface of the socket is provided with at least one slot extending in the circumferential direction, in which a fastening rib of the insulating insert of complementary shape extends.

[0034] This further improves the axial attachment of the insulating insert to the socket.

[0035] 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 lies on the axis of the bearing device.

[0036] If the insulating insert is made of a synthetic material or an elastomer material, this makes the device less sensitive to temperature fluctuations.

[0037] In one particular embodiment, the bushing is made of metal. This allows the bushing to be easily machined to a specified radial tolerance. Advantageously, the bushing is produced from a sheet metal blank by cutting, pressing, and roll bending.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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. Brief character description

[0043] The present invention is better understood by considering the detailed description of embodiments given as a completely 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] a perspective partial exploded view of the storage device from Fig. 1 is, in which an insulating insert of the device is not shown, and [ Fig. 3] is a half-view in axial section of a bearing device according to another exemplary embodiment of the invention. Detailed description of the invention

[0044] 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.

[0045] The bearing device was designed so that it does not conduct electrical currents. The bearing device has integrated electrical insulation.

[0046] 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.

[0047] In the exemplary embodiment shown, 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 rings.

[0048] 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) axially delimiting the bore and the outer surface.

[0049] 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.

[0050] 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.

[0051] The outer ring 14 comprises a cylindrical, axial outer surface 14a, a cylindrical bore 14b radially opposite the outer surface 14a, and two opposing radial end 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.

[0052] In the illustrated exemplary embodiment, the outer surface 14a of the ring has two different diameters. Alternatively, the outer surface 14a could have a single diameter.

[0053] 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.

[0054] In the illustrated exemplary embodiment, a first groove 22 is formed on the end face 14c of the outer ring. The groove 22 is directed axially towards the outside of the outer ring. The groove 22 has a bottom that is offset axially towards the inside of the ring with respect to the end face 14c. The bottom of the groove 22 forms a shoulder. For reasons of ease of manufacture, the bottom of the groove 22 extends radially in this case. The groove 22 is annular in this case.

[0055] Similarly, a second groove 24 is formed on the end face 14d of the outer ring. The groove 24 is oriented axially towards the outside of the outer ring. The groove 24 has a bottom that is offset axially towards the inside of the ring with respect to the end face 14d. The bottom of the groove 24 forms a shoulder. For ease of manufacturing, 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.

[0056] The bearing device 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 attached to the outer ring 14.

[0057] 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. The insulating insert 30 is overmolded onto the outer ring 14 and the bushing 28.

[0058] The bushing 28 has an annular shape. The bushing 28 is formed in one piece. In this case, the bushing 28 is formed from a single piece. The bushing 28 is preferably made of steel. The bushing 28 can advantageously be obtained from a sheet blank by cutting, pressing, and roll bending. Alternatively, the bushing 28 can also be produced from a tube or from a forged and / or rolled blank, or by sintering and stamping.

[0059] The bushing 28 comprises an axial section 32a and first and second annular, radial flanges 32b, 32c, each extending the axial section radially inwards. Each flange 32b, 32c extends radially. Each flange 32b, 32c extends an axial end of the axial section 32a. In the illustrated exemplary embodiment, the flanges 32b, 32c are annular. Alternatively, at least one of the flanges 32b, 32c could be in the form of sectors spaced apart from each other circumferentially.

[0060] The bushing 28 comprises a cylindrical, axial outer surface 28a and a cylindrical bore 28b, which is radially opposite the outer surface 28a and whose axis 25 is coaxial with the axis XX'. The bore 28b forms the inner surface of the bushing 28. The axial section 32a of the bushing bounds the outer surface 28a and the bore 28b. The outer surface 28a and the bore 28b define the radial thickness of the bushing 28. The outer surface 28a 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.

[0061] The bushing 28 also includes two opposing radial end faces 28c, 28d, which axially delimit the outer surface 28a. The end faces 28c, 28d define the axial length of the bushing. The end face 28c is delimited by the flange 32b, and the end face 28d is delimited by the flange 32c. More precisely, the end face 28c is delimited by the outer surface of the flange 32b, and the end face 28d is delimited by the outer surface of the flange 32c.

[0062] 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, it might be possible to provide other arrangements. 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.

[0063] The radial dimension of flange 32c of the bushing is larger than the radial dimension of flange 32b. Flanges 32b and 32c of the bushing are asymmetrical with respect to a radial center plane of the device.

[0064] In the illustrated exemplary embodiment, the flange 32b is radially recessed with respect to the outer surface 14a of the outer ring. In other words, the free end of the flange 32b is radially recessed towards the outside with respect to the outer surface 14a. The flange 32b is radially recessed from the groove 22 of the outer ring.

[0065] In the illustrated exemplary embodiment, the flange 32c of the bushing extends radially beyond the outer surface 14a of the outer ring, i.e., it projects radially inwards with respect to the outer surface 14a. In other words, the free end of the flange 32c is offset radially inwards with respect to the outer surface 14a of the outer ring. The flange 32c extends partially into the groove 24 of the outer ring. The flanges 32b and 32c are spaced at a distance from the outer ring 14a.

[0066] 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.

[0067] 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 30 completely covers the outer surface 14a in both the axial and circumferential directions. The insulating insert 30 covers the grooves 22 and 24 of the outer ring.

[0068] 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. The insulating insert 30 covers the bore in the axial section 32a of the bushing.

[0069] The insulating insert 30 also covers the inner surface of each flange 32b, 32c of the bushing. The inner surface and the outer surface, axially opposite the inner surface of each flange 32b and 32c, define the axial thickness of the flange. For each flange 32b and 32c, the inner surface faces axially towards the inside of the device, and the outer surface faces axially towards the outside of the device. The insulating insert 30 also covers the free end of each flange 32b, 32c of the bushing.

[0070] 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 end faces 30c, 30d axially delimit 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 outer surface 30a is also in radial contact with the free end of each flange 32b, 32c of the bushing. The outer surface 30a has a stepped shape. 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.

[0071] In the illustrated embodiment, the surfaces 14c, 30c, 28c and 14d, 30d, 28d of the outer ring, the insulating insert and the bushing are each coplanar.

[0072] 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.

[0073] 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.

[0074] The following procedure is followed to manufacture the storage device.

[0075] In a first step, the bearing 10 and the bushing 28 are fixed in a mold designed for overmolding the insulating insert 30. In this position fixed in the mold, the bushing 28 is radially spaced from the outer ring 14 of the bearing. The bearing 10 was previously inserted into the interior of the bushing 28 in the direction of the small flange 32b.

[0076] Then, during a subsequent second step, the insulating insert 30 is overmolded onto both the outer ring 14 of the bearing and the bushing 28.

[0077] Finally, the storage device, which is in the form of a single, unified whole, is removed from the mold.

[0078] The in Fig.The exemplary embodiment shown in Figure 3, in which identical elements bear the same reference numerals, differs from the previous example in that the bore in the axial section 32a of the bushing is provided with two slots 36, 38, which are axially spaced apart and extend circumferentially around the axis 25 of the bore in the bushing. Each slot 36, 38 is directed radially towards the outer ring 14, i.e., radially towards the inside.

[0079] In the illustrated exemplary embodiment, each slot 36, 38 is annular. Alternatively, at least one of the two slots 36, 38 could not extend through 360°, or could be formed as a sequence of rotations that extend circumferentially and are spaced apart from each other in the circumferential direction.

[0080] Each slot 36, 38 is bounded axially by two opposing lateral flanges, which have a straight profile in axial section and are connected to each other by an axial base. Alternatively, other shapes are possible, for example, slots which in this case have the cross-sectional shape of a circular arc directed inwards. In another variant, the bushing 28 may also have no slots 36, 38.

[0081] The insulating insert 30 also includes two ribs 40, 42, which extend radially outwards from the outer surface 30a and are accommodated in the slots 36, 38 of the bushing. The rib 40, 42 has a complementary shape to the corresponding slots 36, 38. Each rib 40, 42 projects from the outer surface 30a of the insulating insert. Each rib 40, 42 is formed on the outer surface 30a during the overmolding of the insulating insert 30.

[0082] 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 onto which the insulating insert 30 is overmolded.

[0083] Alternatively, a reverse arrangement can be provided in which the second ring 14, onto which the insulating insert 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 insert is then inserted radially between the bore 12a in the inner ring and the outer surface of the bushing. The insulating insert is overmolded onto the inner ring and at least onto the outer surface of the bushing. The bore in the bushing defines the bore in the bearing device.

[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 one-piece 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 an outer surface (28a) and an inner surface (28b) on the side opposite the outer surface, which limit the radial thickness of the bushing, wherein the insulating insert (30) is overmolded onto the second ring (14) of the bearing and onto at least one of the outer and inner surfaces of the bushing (28), characterized by, that the bushing (28) comprises an axial section (32a) that limits the surface of the bushing (28) on which the insulating insert (30) is overmolded, and first and second flanges (32b, 32c) that extend the axial section radially in the direction of the second ring (14), wherein the insulating insert (30) is also overmolded onto an inner surface of each of the first and second flanges (32b, 32c), the radial dimension of the second flange (32c) being larger than the radial dimension of the first flange (32b). [2] Device according to claim 1, wherein the second flange (32c) of the bushing extends radially beyond an outer surface (14a) or inner surface of the second ring on which the insulating insert (30) is overmolded. [3] Device according to claim 2, wherein the first flange (32b) of the bushing is set back radially from the outer surface (14a) or the inner surface of the second ring. [4] Device according to claim 3, wherein a first groove (22) is formed in a first end face of the second ring (14) and a second groove (24) is formed in a second end face of the second ring (14), wherein the first and second grooves (22, 24) axially limit the outer surface (14a) or the inner surface of the second ring, wherein the first flange (32b) of the bushing is radially spaced from the first groove (22) and the second flange (32c) extends partially into the second groove (24). [5] Device according to one of the preceding claims, wherein the insulating insert (30) comprises two end faces (30c, 30d) that limit the axial length of the insert, wherein at least one of the first and second flanges (32b, 32c) of the bushing is axially flush with one of the end faces (30c, 30d) of the insulating insert. [6] Device according to one of the preceding claims, wherein the surface of the bushing (28) is provided with at least one slot (36) extending in the circumferential direction and in which at least one fastening rib (40) of the insulating insert of complementary shape extends. [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 produced from a sheet metal blank by cutting, pressing and roll bending. [9] Device according to one of the preceding claims, wherein the insulating insert (30) is made of a synthetic material or of an elastomeric material. [10] Electric motor comprising a housing, a shaft and at least one bearing device according to any one of claims 1 to 9, which is mounted radially between the housing and the shaft.

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