Bearing arrangement with integrated electrical insulation, in particular for electric motor or machine

Abstract

The invention relates to a bearing arrangement with integrated electrical insulation, in particular for an electric motor or machine. The bearing arrangement comprises a bearing (10) provided with a first ring (12) and a second ring (14) rotatable relative to each other. The device comprises at least one insulating sleeve (36) mounted on the second ring of the bearing and provided with a bushing (40) and an insulating insert (38) positioned radially between the second ring and the bushing and made of an electrically insulating material. The second ring includes an outer surface (14a) defining a radial thickness of the outer second ring and an inner surface (14b) opposite the outer surface. An insulative insert is overmolded on the liner and at least on one of the inner and outer surfaces of the second ring. At least a first groove is formed on the inner or outer surface of the second ring. The slots are spaced apart from each other in a circumferential direction, and ribs having complementary shapes for attaching the insulating inserts extend inside each of the slots.

Description

Technical Field

[0001] The present invention relates to the field of bearings, in particular to the field of bearings for electric motors, electric machines and associated equipment. Background Art

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

[0003] During operation, when the shaft rotates, a potential difference may occur between the housing of the electric motor or electric machine and the shaft, resulting in a current flow between the inner ring (rigidly connected to the shaft) and the outer ring (rigidly connected to the housing) of the rolling bearing.

[0004] The current flowing through the components of the rolling bearing can damage these components, in particular the rolling elements and the raceways provided on the inner and outer rings. The discharge can also generate vibrations.

[0005] In order to overcome these drawbacks, it is known to replace the rolling elements of the bearing made of the same steel as the inner and outer rings with rolling elements made of ceramic. The expression "hybrid rolling bearing" is then often used.

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

[0007] In order to overcome the aforementioned drawbacks, it is also known to equip the outer ring of the rolling bearing with an insulating sleeve provided with a bushing and an insulating insert made of an electrically insulating material and positioned radially between the outer ring and the bushing.

[0008] In order to attach the insulating insert to the outer ring and the bushing without any additional elements or specific machining of the outer ring, the insulating insert may be over-molded.

[0009] However, with this solution, relative uncoupling of the insulating insert and the bushing may occur during operation.

[0010] It is therefore an object of the present invention to overcome the aforementioned disadvantages by providing a bearing arrangement having a simple and economical design. Summary of the Invention

[0011] The present invention relates to a bearing arrangement comprising a bearing provided with a first ring and a second ring which are rotatable relative to each other.

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

[0013] The second ring includes an outer surface defining a radial thickness of the second ring and an inner surface opposite the outer surface.

[0014] The insulating insert is overmoulded onto the bushing and onto at least one of the inner and outer surfaces of the second ring of the bearing.

[0015] According to general characteristics, the inner or outer surface of the second ring has a tiered shape, with a cylindrical main part and at least a first cylindrical lateral part, which is arranged axially to one side of the main part and is radially offset relative to the main part on the other outer or inner surface of the second ring.

[0016] According to another general feature, said inner or outer surface of said second collar is additionally provided with a first connecting surface extending between said first cylindrical lateral portion and said cylindrical main portion.

[0017] According to yet another general feature, at least the first connection face is provided with a plurality of first grooves spaced apart from one another in the circumferential direction and inside each of which a rib of complementary shape for attaching the insulating insert extends.

[0018] This provides a bearing arrangement with integrated electrical insulation and which is economical compared to conventional hybrid rolling bearings. Furthermore, the arrangement is easy to manufacture and assemble in an associated electric motor or electric machine.

[0019] Furthermore, the provision of grooves on the inner or outer surface of the second bearing ring makes it possible to provide a good rigid connection with the insulating insert, provided that the attachment ribs are formed inside these grooves during overmolding. The risk of relative movement between the insulating insert and the second ring in the axial and circumferential directions is particularly limited, especially in the event of temperature fluctuations.

[0020] "Axial direction" is understood to mean a direction parallel to the axis of the bearing arrangement.

[0021] "Circumferential direction" is understood to mean a direction perpendicular to the axial direction and perpendicular to a radius of the bearing arrangement, in other words tangent to a circle centred on the axis of the bearing arrangement.

[0022] Furthermore, providing the grooves on the first connection surface of the inner or outer surface of the second bearing ring limits the variations in material thickness around the grooved area, which would be associated with arranging the grooves in the area of ​​the main part adjacent to the first connection surface. This limits stress concentrations in the areas of reduced thickness of the second ring.

[0023] Preferably, the first connecting surface of the inner or outer surface of the second ring at least partially extends radially from the cylindrical main portion.

[0024] According to a first design, the first connecting surface at least partially extends obliquely from the cylindrical body portion, ie in the radial direction and in the axial direction.

[0025] According to a second design, the first connecting surface extends at least partially purely in radial direction from the cylindrical main part.

[0026] Each of the first grooves of the first connecting face of the inner or outer surface of the second ring may be delimited in the circumferential direction by two facing lateral flanks.

[0027] In one embodiment, the inner or outer surface of the second ring is provided with only a cylindrical main portion and a first cylindrical lateral portion.

[0028] In another embodiment, the inner or outer surface of the second ring is provided with a second cylindrical lateral portion, the second cylindrical lateral portion being radially offset relative to the main portion on the other outer or inner surface of the second ring, the first cylindrical lateral portion and the second cylindrical lateral portion being axially arranged one on each side of the cylindrical main portion. The first and second lateral portions may have the same or different diameters.

[0029] In this case, the inner or outer surface of the second ring is provided with a second connecting surface extending between the second cylindrical lateral portion and the central portion. Preferably, the second connecting surface is provided with a plurality of second grooves spaced apart from one another in the circumferential direction, and a rib having a complementary shape for attaching the insulating insert extends inside each of the plurality of second grooves.

[0030] According to one particular design, the cylindrical main portion of the inner or outer surface of the second ring can be provided with a plurality of grooves spaced apart from one another in the circumferential direction and with a rib of complementary shape extending inside each of the plurality of grooves for attaching the insulating insert.

[0031] If the insulating insert is made of a synthetic or elastomeric material, this makes the device relatively insensitive to temperature changes.

[0032] In a specific embodiment, the bushing is made of a metal material. Therefore, the bushing can be easily machined to a predetermined radial tolerance.

[0033] According to a first design, the bushing defines the outer surface of the device. In this case, the second ring is the outer ring of the bearing.

[0034] According to an alternative second design, the bushing defines the inner surface of the device. In this case, the second ring is the inner ring of the bearing.

[0035] In a particular embodiment, the bearing comprises at least one row of rolling elements arranged between the raceway of the first ring and the raceway of the second ring.The rolling elements may be made of a metallic material.

[0036] The invention also relates to an electric motor comprising a housing, a shaft and at least one bearing device as defined above, mounted radially between the housing and the shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention will be better understood by reference to the detailed description of embodiments provided by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0038] Figure 1 is a semi-axial cross-sectional view of a bearing device according to an exemplary embodiment of the present invention,

[0039] Figure 2 yes Figure 1A three-dimensional view of the outer ring of the bearing assembly,

[0040] Figure 3 yes Figure 2 Detailed view of

[0041] Figure 4 is a perspective view of an outer ring of a bearing device according to another exemplary embodiment of the present invention,

[0042] Figure 5 yes Figure 4 Detailed view of

[0043] Figure 6 is a semi-axial cross-sectional view of a bearing device according to another exemplary embodiment of the present invention,

[0044] Figure 7 yes Figure 6 A three-dimensional view of the outer ring of the bearing assembly,

[0045] Figure 8 yes Figure 7 Detailed view of the . DETAILED DESCRIPTION

[0046] Figure 1 The bearing arrangement shown in comprises a bearing 10 provided with a first ring 12 and a second ring 14 rotatable relative to each other about an axis XX' of the bearing. In the embodiment shown, the first ring 12 is the inner ring of the bearing and the second ring 14 is the outer ring.

[0047] The bearing arrangement is designed such that the bearing arrangement does not conduct electrical current. The bearing arrangement has integrated electrical insulation.

[0048] 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 of solid type.

[0049] In the exemplary embodiment shown, bearing 10 also includes an array of rolling elements 16 (in this case, balls) positioned radially between inner ring 12 and outer ring 14. Rolling elements 16 are constructed from steel. Bearing 10 also includes a cage 17 for maintaining even circumferential spacing of rolling elements 16. Bearing 10 may also be equipped with seals or sealing flanges.

[0050] Inner ring 12 includes a cylindrical bore 12a, a cylindrical axial outer surface 12b radially opposite the bore, and two opposing radial end surfaces (not shown) axially delimiting the bore and the outer surface. Bore 12a and outer surface 12b define the radial thickness of inner ring 12. Bore 12a forms the inner surface of the inner ring.

[0051] The inner ring 12 further comprises an inner raceway 18 formed on the outer surface 12b for the rolling elements 16. The raceway 18 points radially outward.

[0052] The outer ring 14 includes a cylindrical axial outer surface 14a, a cylindrical hole 14b radially opposite the outer surface 14a, and two opposite radial end surfaces 14c, 14d axially delimiting the outer surface and the hole. The outer surface 14a and the hole 14b define the radial thickness of the outer ring 14.

[0053] The outer surface 14a has a stepped shape. It includes a large-diameter annular cylindrical central portion 20 and first and second annular cylindrical lateral portions 22, 24 of smaller diameter, one each arranged axially on either side of the central portion. The lateral portions 22, 24 are radially offset inward relative to the central portion 20, i.e., radially offset relative to the central portion 20 toward the bore 14b.

[0054] The outer surface 14a is further provided with a first annular connecting surface 26 extending between the first lateral portion 22 and the central portion 20. The first connecting surface 26 has a frustoconical portion extending obliquely inward in the radial direction and outward in the axial direction from the central portion 20, and a radial portion continuing from a small-diameter edge of the frustoconical portion and connected to the first lateral portion 22.

[0055] The outer surface 14a is further provided with a second annular connecting surface 28 extending between the second lateral portion 24 and the central portion 20. The second connecting surface 28 has a frustoconical portion extending obliquely inward in the radial direction and outward in the axial direction from the central portion 20, and a radial portion continuing the small-diameter edge of the frustoconical portion and connected to the second lateral portion 24. The outer ring 14 is symmetrical with respect to a radial median plane passing through the center of the rolling element 16.

[0056] Reference Figure 2 and Figure 3 The outer ring 14 is provided with first grooves 30 formed on the first connection surface 26. The first grooves 30 are formed in a frustoconical portion of the first connection surface 26. The first grooves 30 extend radially inward from the first connection surface 26. The first grooves 30 are immediately adjacent to each other in the circumferential direction. Each first groove 30 is circumferentially bounded by two opposing lateral sides, which have straight profiles in axial cross-section and are connected to each other.

[0057] In this case, the first grooves 30 are formed completely around the periphery of the first connecting surface 26. Alternatively, the first grooves 30 may extend over an angular sector of less than 360° or be arranged in groups of grooves spaced apart from one another in the circumferential direction. The first grooves 30 may be formed on the first connecting surface 26 by knurling.

[0058] The outer ring 14 is further provided with second grooves 32 formed in the second connection surface 28. The grooves 32 are formed in a frustoconical portion of the second connection surface 28. The second grooves 32 extend radially inward from the second connection surface 28. The second grooves 32 are immediately adjacent to one another in the circumferential direction. Each second groove 32 is circumferentially bounded by two opposing lateral sides, which have a straight profile in axial cross-section and are connected to one another.

[0059] In this case, the second grooves 32 are formed completely around the circumference of the second connecting surface 28. Alternatively, the second grooves 32 may extend over an angular sector of less than 360° or be arranged in groups of grooves spaced apart from one another in the circumferential direction. The second grooves 32 may be formed on the second connecting surface 28 by knurling.

[0060] Refer again Figure 1 The outer ring 14 further includes an outer raceway 34 formed on the bore 14b for the rolling elements 16. The raceway 20 points radially inward.

[0061] The bearing arrangement further comprises an electrically insulating sleeve 36 mounted on the outer ring 14. The insulating sleeve 36 is mounted on the outer surface 14a of the outer ring 14. The insulating sleeve 36 is rigidly connected to the outer ring 14.

[0062] The insulating sleeve 36 includes the bushing 20 and an insulating insert 38 positioned radially between the outer ring 14 and the bushing 40. The insulating insert 38 is overmolded onto the outer ring 14 and the bushing 40.

[0063] The bushing 40 is annular. The bushing 40 extends in the axial direction. In this case, the bushing 40 is made as a single piece. Alternatively, the bushing 40 can be made of multiple parts (for example, two identical parts) that abut against each other. The bushing 40 includes an axial portion 42, a first radial flange 44 that continues radially inward from one end of the axial portion 42, and a second radial flange 46 that continues radially inward from the opposite end of the axial portion 42. In the exemplary embodiment shown, the radial flanges 44, 46 are annular. The radial flanges 44, 46 remain at a distance from the outer ring 14.

[0064] Bushing 40 includes a cylindrical axial outer surface 40a and a cylindrical bore 40b radially opposite outer surface 40a. Bore 40b forms the inner surface of bushing 40. An axial portion 42 of the bushing defines outer surface 40a and bore 40b. Outer surface 40a and bore 40b define the radial thickness of bushing 40. Bushing outer surface 40a forms the outer surface of bearing assembly 10. In other words, outer surface 40a defines the outer diameter of bearing assembly 10.

[0065] The bushing 40 also includes two opposing radial end faces 40c and 40d that axially define the outer surface 40a. The end faces 40c and 40d define the axial length of the bushing. The end face 40c is defined by a radial flange 44, and the end face 40d is defined by a radial flange 46. More specifically, the end face 40c is defined by the outer face of the radial flange 44, and the end face 40d is defined by the outer face of the radial flange 46.

[0066] In the exemplary embodiment shown, the end faces 40c, 40d of the bushing are coplanar with the end faces 14c, 14d of the outer ring, respectively. Alternatively, other configurations may be provided. For example, the bushing 40 may have a smaller or larger axial dimension and may be axially set back from the outer ring faces 14c, 14d, or may protrude therefrom.

[0067] The insulating insert 38 is made of an electrically insulating material. The insulating insert 38 may, for example, be made of a synthetic material such as PEEK or PA46, or the insulating insert 38 may be made of an elastomeric material such as rubber.

[0068] The insulating insert 38 is positioned radially between the outer surface 14a of the outer ring and the bore 40b of the bushing. The insulating insert 38 covers the outer surface 14a of the outer ring. In the present case, the insulating insert 38 completely covers the outer surface 14a in the axial and circumferential directions.

[0069] The insulating insert 38 also covers the bore 40b of the bushing. In this case, the insulating insert 38 completely covers the bore 40b in both the axial and circumferential directions. The insulating insert 38 also covers the inner faces of the radial flanges 44, 46 of the bushing. The insulating insert 38 also covers the free ends of the radial flanges 44, 46 of the bushing.

[0070] The insulating insert 38 is annular. It extends axially. It includes a cylindrical axial outer surface 38a, a cylindrical bore 38b radially opposed to the outer surface 38a, and two opposing radial end surfaces 38c and 38d that axially define the bore and the outer surface. The radial end surfaces 38c and 38d axially delimit the insulating insert 38. The outer surface 38a and the bore 38b define the radial thickness of the insulating insert. The outer surface 38a radially contacts the bore 40b of the bushing. The outer surface 38a also radially contacts the free end of each radial flange 44 and 46 of the bushing. The outer surface 38a has a stepped shape. The bore 38b radially contacts the outer surface 14a of the outer ring. The bore 38b has a stepped shape.

[0071] In the exemplary embodiment shown, the faces 14c, 38c, 40c and 14d, 38d, 40d of the outer race, insulating insert, and bushing, respectively, are coplanar.

[0072] Alternatively, other configurations may be provided. For example, the insulating insert 38 may have a reduced axial dimension and remain axially set back from the outer ring faces 14c, 14d. Alternatively, the insulating insert 38 may have a larger axial dimension and protrude axially from the outer ring faces 14c, 14d. In this case, the insulating insert 38 may at least partially cover these faces 14c, 14d. As a variant, the insulating insert 38 may at least partially cover the bushing faces 40c, 40d.

[0073] In another alternative or combination, the bushing 40 may protrude axially from the insulating insert 38 relative to the faces 38c and 38d, or may remain axially set back from these faces.

[0074] The insulating insert 38 also includes a plurality of first ribs extending inwardly from the aperture 38 b and each of which is received in one of the grooves 30 of the outer ring. Each first rib has a shape complementary to that of the associated groove 30. Each first rib protrudes relative to the aperture 38 b of the insulating insert. Each first rib is formed on the aperture 38 b during overmolding of the insulating insert 38.

[0075] The insulating insert 38 also includes a plurality of second ribs extending inwardly from the aperture 38 b and each of which is received in one of the grooves 32 of the outer ring. Each second rib has a shape complementary to that of the associated groove 32. Each second rib protrudes relative to the aperture 38 b of the insulating insert. Each second rib is formed in the aperture 38 b during overmolding of the insulating insert 38.

[0076] The bearing device is manufactured as follows.

[0077] In a first step, the bearing 10 and the bushing 40 are mounted inside a mould provided for overmoulding the insulating insert 38. In this position mounted inside the mould, the bushing 40 is radially spaced apart from the outer ring 14 of the bearing.

[0078] Then, in a successive second step, the insulating insert 38 is overmoulded onto the outer ring 14 of the bearing and onto the bushing 40. The first and second ribs of the insulating insert are formed during this step.

[0079] Finally, the bearing device is removed from the mold in the form of an integral assembly.

[0080] Figure 4 and Figure 5 The illustrated exemplary embodiment (in which like elements bear like reference numerals) differs from the previously described examples in that the outer surface of outer ring 14 is provided with a third groove 50 formed in central portion 20. Groove 50 is spaced apart from grooves 30 and 32. Grooves 50 extend radially inward from central portion 20. Grooves 50 are circumferentially adjacent to one another. Each groove 50 is circumferentially bounded by two opposing lateral sides that, in axial cross-section, have a straight profile and are connected to one another.

[0081] In this case, the grooves 50 are formed completely around the periphery of the central portion 20. Alternatively, the grooves 50 may extend over an angular sector of less than 360° or be arranged in groups of grooves spaced apart from one another in the circumferential direction. The grooves 50 may be formed on the central portion 20 by knurling. In a manner similar to the first and second grooves, third ribs extending inwardly from the bore 38b and each received in one of the grooves 50 of the outer ring are formed during overmolding of the insulating insert.

[0082] Figures 6 to 8 The illustrated exemplary embodiment (in which like elements bear like reference numerals) differs from the first example in that the outer surface 14a is provided with a first connecting surface 52 extending between the first lateral portion 22 and the central portion 20 and having a radial portion extending radially inward from the central portion 20 and a concave gap continuing the small-diameter edge of the radial portion and connecting to the first lateral portion 22. The groove 30 is formed on the connecting surface 52. The groove 30 is formed on the radial portion of the connecting surface 52.

[0083] The outer surface 14a is further provided with a second connecting surface 54, which extends between the second lateral portion 24 and the central portion 20 and has a radial portion extending radially inward from the central portion 20 and a concave gap that continues the small-diameter edge of the radial portion and connects to the second lateral portion 24. The groove 32 is formed on the connecting surface 54. The groove 32 is formed on the radial portion of the connecting surface 54.

[0084] In an embodiment variant, as described above, a third groove may also be provided on the central portion 20 of the outer surface of the outer ring.

[0085] In the embodiment shown, the first race 12 of the bearing is the inner race and the second race 14 onto which the insulating insert 38 is overmolded is the outer race.

[0086] Alternatively, a reverse configuration can be provided, in which the second ring 14 onto which the insulating insert 38 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 positioned radially between the bore 12a of the inner ring and the outer surface of the bushing. The insulating insert is overmolded onto the outer surface of the bushing and onto the bore of the inner ring, which is provided with a groove and forms the inner surface of the inner ring. The bore of the bushing defines the bore of the bearing arrangement.

[0087] In the described embodiment, the bearing of the device is provided with a single row of rolling elements. In one variation, the bearing may be provided with multiple rows of rolling elements. Furthermore, the rolling bearing may include other types of rolling elements besides balls, such as rollers. In another variation, the bearing may be a plain bearing without rolling elements.

Claims

1. A bearing device comprising a bearing (10) and an insulating sleeve (36), the bearing (10) being provided with a first ring (12) and a second ring (14) capable of rotating relative to each other, the insulating sleeve (36) being mounted on the second ring (14) of the bearing and being provided with a bushing (40) and an insulating insert (38), the insulating insert (38) being positioned radially between the second ring (14) and the bushing (40) and being made of an electrically insulating material, the second ring (14) comprising an outer surface (14a) defining a radial thickness of the outer second ring and an inner surface (14b) opposite the outer surface, the insulating insert (38) being overmolded onto the bushing (40) and overmolded onto at least one of the inner and outer surfaces of the second ring (14), characterized in that: - said inner or outer surface of said second ring has a stepped shape, with a cylindrical main portion (20) and at least a first cylindrical lateral portion (22), said first cylindrical lateral portion (22) being arranged axially to one side of said main portion (20) and being radially offset relative to said main portion (20) on the other outer or inner surface of said second ring, - said inner or outer surface of said second ring is additionally provided with a first connecting surface (26; 52) extending between said first cylindrical lateral portion (22) and said cylindrical main portion (20), - at least the first connection face (26; 52) is provided with a plurality of first grooves (30) spaced apart from one another in the circumferential direction and inside each of which a rib of complementary shape for attaching the insulating insert extends.

2. The device according to claim 1, characterized in that A first connecting surface (26; 52) of the inner or outer surface of the second ring extends at least partially radially from the cylindrical main portion (20).

3. The device according to claim 2, characterized in that A first connecting surface (26) of the inner or outer surface of the second ring extends at least partially obliquely from the cylindrical main portion (20).

4. The device according to claim 2, characterized in that The first connecting surface (52) of the inner or outer surface of the second ring extends at least partially only in radial direction from the cylindrical main part (20).

5. The device according to any one of the preceding claims, characterized in that Each of the first grooves (30) of the first connecting surface (26; 52) of the inner or outer surface of the second ring is delimited in the circumferential direction by two facing lateral sides.

6. The device according to any one of the preceding claims, characterized in that The inner or outer surface of the second ring is provided with a second cylindrical lateral portion (24), which is radially offset on the other outer or inner surface of the second ring relative to the main portion (20), the first cylindrical lateral portion (22) and the second cylindrical lateral portion (24) being arranged one on each side of the cylindrical main portion (20) in the axial direction, and the inner or outer surface of the second ring is provided with a second connecting surface (28; 54) extending between the second cylindrical lateral portion (24) and the central portion (20), the second connecting surface (28; 54) being provided with a plurality of second grooves (32), the plurality of second grooves (32) being spaced apart from each other in the circumferential direction, and a rib of complementary shape for attaching the insulating insert extending inside each of the plurality of second grooves (32).

7. The device according to any one of the preceding claims, characterized in that The cylindrical main portion (20) of the inner or outer surface of the second ring is provided with a plurality of grooves (50) spaced apart from each other in the circumferential direction, and a rib of complementary shape for attaching the insulating insert extends inside each of the plurality of grooves (50).

8. The device according to any one of the preceding claims, characterized in that The second ring (14) is the outer ring of the bearing.

9. The device according to any one of the preceding claims, characterized in that The bushing (40) is made of metal material.

10. An electric motor comprising a housing, a shaft and at least one bearing arrangement according to any one of the preceding claims, the bearing arrangement being mounted radially between the housing and the shaft.

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