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

Abstract

The invention relates to a bearing arrangement with integrated electrical insulation, in particular for an electric machine or motor. The device comprises a bearing (10) provided with a first ring (12) and a second ring (14). The device comprises an insulating sleeve (26) mounted on the second ring and provided with a bushing (28) and an insulating insert (30). An insulating insert is secured to the second ring and at least to one of the outer and inner surfaces of the bushing (28). The bushing (28) further includes a first front face (28c) and a second front face (28d) defining an axial length of the bushing. A first connection chamfer (28e) connects a first front 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, a second concave radius connected to the first front face (28c) while forming another sharp edge, and a frustoconical surface extending between the first concave radius and the second concave radius.

Description

Technical Field

[0001] This invention relates to the field of bearings, particularly to bearings used in electric motors, electric machines and related equipment. Background Technology

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

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

[0004] Current flowing through the components of a rolling bearing can damage these components (especially the rolling elements and the raceways formed in the inner and outer rings). Electrical shocks can also cause vibrations.

[0005] To overcome these shortcomings, it is known to replace the rolling elements of bearings made of the same steel as the inner and outer rings with ceramic rolling elements. This type of bearing is often referred to as a hybrid rolling bearing.

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

[0007] To overcome the above-mentioned shortcomings, it is also known to equip the outer ring of the rolling bearing with an insulating sleeve, which is provided with a bush and an insulating insert made of electrically insulating material and located radially between the outer ring and the bush.

[0008] When installing the bearing assembly inside or removing it from the motor housing, the holes in the housing may be damaged.

[0009] The present invention aims to overcome this shortcoming. Summary of the Invention

[0010] The present invention relates to a bearing device comprising a bearing having a first and a second ring capable of rotating relative to each other.

[0011] The device further includes at least one insulating sleeve mounted on the second ring of the bearing. The insulating sleeve has a bushing and an insulating insert radially positioned between the second ring of the bearing and the bushing. The insulating insert is made of an electrically insulating material.

[0012] The bushing includes a cylindrical outer surface defining the radial thickness of the bushing and a cylindrical inner surface on the opposite side of the outer surface. The bushing also includes a first frontal face and a second frontal face defining the axial length of the bushing.

[0013] The insulating insert is fastened 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 feature, a first connecting chamfer connects the first front face of the bushing to the other surface of the bushing's outer and inner surfaces.

[0015] The first connecting chamfer has a first concave radius, a second concave radius, and a frustoconical surface extending between the first concave radius and the second concave radius. The first concave radius forms a sharp edge while connecting to the other surface of the bushing, and the second concave radius forms another sharp edge while connecting to the first front surface.

[0016] This results in a bearing assembly with integrated electrical insulation, which is more economical than conventional hybrid rolling bearings.

[0017] Furthermore, given the presence of a first connecting chamfer with a truncated shape, the device is easily assembled into the associated electric machine or motor without the risk of damaging the holes in the electric motor or machine.

[0018] Each sharp edge forms a slope change between the first connecting chamfer and the other surface of the bushing or between the first connecting chamfer and the first front surface of the bushing.

[0019] The first connecting chamfered truncated conical surface reduces the spurious nature of each sharp edge.

[0020] Preferably, the first concave radius and the second concave radius 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 ​​can be provided.

[0022] Preferably, the second connecting chamfer connects the second front surface of the bushing to the other surface of the bushing.

[0023] In this case, the second connecting chamfer advantageously has a first concave radius, a second concave radius, and a truncated conical surface extending between the first concave radius and the second concave radius, the first concave radius connecting to the other surface of the bushing while forming a sharp edge, and the second concave radius connecting to the second front surface while forming another sharp edge.

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

[0025] The second concave radius of the second connecting chamfer is equal to the value of the first concave radius. Alternatively, different values ​​can be provided.

[0026] Advantageously, the bushing is made of a metallic material. The bushing may be obtained, for example, by pressing or machining.

[0027] Preferably, the insulating insert is overmolded on the second ring of the bearing and at least overmolded on the surface of the bushing. Alternatively, the insulating insert can be secured by any other suitable means, such as by adhesive bonding.

[0028] If the insulating insert is made of synthetic or elastomeric materials, the device is less sensitive to temperature changes.

[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" refers to the direction parallel to the axis of the bearing assembly.

[0031] The term "circumferential direction" refers to a direction perpendicular to the axial direction and the radius of the bearing assembly; in other words, it is tangent to a circle centered on the axis of the bearing assembly.

[0032] According to the first design, 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 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.

[0034] In one particular embodiment, the bearing includes at least one row of rolling elements arranged between the raceways of a first ring and a second ring. The rolling elements may be made of a metallic material.

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

[0036] The present invention also relates to a method for manufacturing a bushing for a bearing assembly as defined above, the method comprising the following sequential steps:

[0037] - The step of producing bush blanks, which give the bushing its basic geometry.

[0038] - A heat treatment step to impart the required hardness to the bushing blank.

[0039] - The step of radially grinding a portion of the first front surface of the bushing blank and the second concave radius of the first connecting chamfer adjacent to the first front surface, and

[0040] - The step of grinding the other surface of the bushing blank and a portion of the first concave radius of the first connecting chamfer adjacent to the other surface in the axial direction.

[0041] The term "radial direction" refers to the direction along the radius of the bearing assembly, that is, any direction that intersects with and is perpendicular to the axis of the bearing assembly. Attached Figure Description

[0042] The invention will be better understood by studying the detailed description of the embodiments given by way of entirely non-limiting example and illustrated in the accompanying drawings, in which:

[0043] Figure 1 This is a half-view of the axial section of a bearing device according to an exemplary embodiment of the present invention.

[0044] Figure 2 and Figure 3 It comes from Figure 1 Detailed view of the bushing of the device.

[0045] Figure 4 It comes from Figure 1 A three-dimensional view of the bushing of the device, and

[0046] Figure 5 and Figure 6 It comes from Figure 1 Detailed views of the bushings of the device before and after the grinding step. Detailed Implementation

[0047] Figure 1 The illustrated bearing assembly includes a bearing 10, which has a first ring 12 and a second ring 14 that are rotatable relative to each other about the bearing's axis X-X'. In the illustrated exemplary embodiment, the first ring 12 is the inner ring of the bearing, and the second ring 14 is the outer ring.

[0048] The bearing assembly is designed not to conduct current. The bearing assembly has integrated electrical insulation.

[0049] The inner ring 12 and outer ring 14 of the bearing are concentric and extend axially along the bearing axis X-X'. The inner ring 12 and outer ring 14 are made of steel. The rings are solid.

[0050] In the exemplary embodiment shown, the bearing 10 also includes a row of rolling elements 16, in this case balls, radially positioned 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 a regular circumferential spacing between the rolling elements 16. The bearing 10 may also be equipped with seals or flange gaskets.

[0051] The inner ring 12 includes a cylindrical bore 12a, a cylindrical axial outer surface 12b on the opposite side of the bore in the radial direction, and two opposing radial faces (not shown) defining the bore and the outer surface in the axial direction. 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.

[0052] The inner ring 12 also includes an inner raceway 18 formed on the outer surface 12b for the rolling element 16. The raceway 18 points outward in the radial direction.

[0053] The outer ring 14 includes a cylindrical axial outer surface 14a, a cylindrical hole 14b on the opposite side of the outer surface 14a in the radial direction, and two opposing radial faces 14c, 14d defining the hole in the axial direction. The outer surface 14a and the hole 14b define the radial thickness of the outer ring 14. The hole 14b has a stepped shape.

[0054] The outer ring 14 also includes an outer raceway 20 formed on the bore 14b for the rolling element 16. The raceway 20 points radially inward.

[0055] In the exemplary embodiment shown, a groove 22 is formed in the front face 14d of the outer ring. The groove 22 is oriented and opens axially toward the outer side of the outer ring. The groove 22 has a bottom that is offset axially toward the inner side of the ring relative to the front face 14d. The bottom of the groove 22 forms a shoulder. In this case, for ease of manufacture, the bottom of the groove 22 extends radially. In this case, the groove 22 is annular.

[0056] Similarly, a groove 24 is formed in the front face 14c of the outer ring. The groove 24 is oriented and opens axially toward the outer side of the outer ring. The groove 24 has a bottom that is offset axially toward the inner side of the ring relative to the front face 14c. The bottom of the groove 24 forms a shoulder. In this case, the bottom of the groove 24 extends radially. In this case, the groove 24 is annular. The grooves 22 and 24 are symmetrical to each other with respect to the radial midplane of the outer ring. The grooves 22 and 24 define the outer surface 14a axially. Alternatively, the grooves 22 and 24 may not be provided.

[0057] The bearing assembly also includes an electrically insulating sleeve 26 mounted on the outer ring 14. The insulating sleeve 26 is mounted on the outer surface 14a of the outer ring 14. The insulating sleeve 26 is fixed to the outer ring 14.

[0058] The insulating sleeve 26 includes a bushing 28 and an insulating insert 30 radially positioned 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.

[0059] Bushing 28 has an annular shape. Bushing 28, having an axis X-X', extends axially. In this case, bushing 28 is formed as a single piece. Alternatively, bushing 28 can be made of multiple pieces (e.g., two identical pieces) bearing against each other. Bushing 28 includes a cylindrical annular axial outer surface 28a and a cylindrical annular axial bore 28b radially opposite to the outer surface 28a. Bore 28b forms the inner surface of bushing 28. Bore 28b is radially oriented inward (i.e., towards the outer ring 14 and the insulating insert 30). The axis of bore 28b is coaxial with axis X-X'.

[0060] The bushing 28 also includes two opposing radial frontal faces 28c and 28d that define the bore and outer surface in the axial direction. Frontal faces 28c and 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 assembly 10. In other words, the outer surface 28a defines the outer diameter of the bearing assembly 10.

[0061] In the exemplary embodiment shown, the front faces 28c, 28d of the bushing are coplanar with the front faces 14c, 14d of the outer ring, respectively. Alternatively, other configurations may be provided. For example, the bushing 28 may have a smaller or larger axial dimension and may be axially set back from or protrude from the faces 14c, 14d of the outer ring.

[0062] As in Figure 2 and Figure 3 As shown more clearly in the diagram, bushing 28 also includes a first annular connecting chamfer 28e and a second annular connecting chamfer 28f that respectively connect the front surfaces 28c and 28d to the outer surface 28a.

[0063] The first connecting chamfer 28e is provided with a first concave radius 28e1 connected to the outer surface 28a, a second concave radius 28e2 connected to the front surface 28c, and a truncated conical surface 28e3 extending between the first concave radius and the second concave radius and connecting the first concave radius and the second concave radius.

[0064] The first concave radius 28e1 is directly connected to the outer surface 28a. The second concave radius 28e2 is directly connected to the front surface 28c. In other words, for the first concave radius 28e1, there is no additional surface between the first radius and the outer surface 28a, and for the second concave radius 28e2, there is no additional surface between the second radius and the front surface 28c. The truncated conical surface 28e3 is also directly connected to the first and second concave radii.

[0065] The first concave radius 28e1 connects to the outer surface 28a while forming the sharp edge a1, and the second concave radius 28e2 connects to the front surface 28c while forming another sharp edge a2.

[0066] In the exemplary embodiment shown, the first concave radius 28e1 and the second concave radius 28e2 are the same as each other. Therefore, the values ​​of these radii are equal. Alternatively, the values ​​of the first concave radius 28e1 and the second concave radius 28e2 can be different.

[0067] In the same manner as the first connecting chamfer 28e, the second connecting chamfer 28f is provided with a first concave radius 28f1 connected to the outer surface 28a, a second concave radius 28f2 connected to the front surface 28d, and a truncated conical surface 28f3 extending between the first concave radius and the second concave radius and connecting the first concave radius and the second concave radius.

[0068] The first concave radius 28f1 is directly connected to the outer surface 28a. The second concave radius 28f2 is directly connected to the front surface 28d. In other words, for the first concave radius 28f1, there is no additional surface between the first radius and the outer surface 28a, and for the second concave radius 28f2, there is no additional surface between the second radius and the front surface 28d. The truncated conical surface 28f3 is also directly connected to the first and second concave radii.

[0069] The first concave radius 28f1 connects to the outer surface 28a while forming the sharp edge a3, and the second concave radius 28f2 connects to the front surface 28c while forming another sharp edge a4.

[0070] In the exemplary embodiment shown, the first concave radius 28f1 and the second concave radius 28f2 are the same as each other. Therefore, the values ​​of these radii are equal. Alternatively, the values ​​of the first concave radius 28f1 and the second concave radius 28f2 can be different.

[0071] The bushing 28 is made of a metallic material. Preferably, the bushing 28 is made of steel. The bushing 28 can be obtained from sheet metal blanks by cutting, pressing, and rolling. Alternatively, the bushing 28 can be obtained from tubes or from forged and / or rolled blanks, or by stamping.

[0072] To manufacture bushing 28, follow these steps.

[0073] In the first step, a bush blank is produced, which gives the bush a basic geometry with an outer surface 28a, a hole 28b, a front surface 28c, 28d and connecting chamfers 28e, 28f.

[0074] exist Figure 5 and Figure 6 In the figure, the outer surface 28a, connecting chamfers 28e and 28f, and the front surface 28c and 28d of the bushing blank are depicted with dashed lines. The center of the first concave radius 28e1 and the second concave radius 28e2 of the first connecting chamfer 28e is marked with the corresponding reference numeral C. 28e1 C 28e2 The centers of the first concave radius 28f1 and the second concave radius 28f2 of the second connecting chamfer 28f have corresponding reference numerals C. 28f1 C 28f2 .

[0075] Next, in the subsequent second step, the bushing blank is heat-treated to impart the required hardness to the bushing blank.

[0076] Then, in the subsequent third step, the front face 28c of the bushing blank and a portion of the second concave radius 28e2 of the first chamfer adjacent to the front face 28c, and a portion of the front face 28d of the bushing blank and the second concave radius 28f2 of the second chamfer adjacent to the front face 28d, are ground in the radial direction. Sharp edges a2 and a4 are formed during this step.

[0077] During this third step, the outer surface 28a of the bushing blank, a portion of the outer surface 28a adjacent to the first concave radius 28e1 of the first chamfer, and a portion of the outer surface 28d adjacent to the first concave radius 28f1 of the second chamfer are also ground in the axial direction. Sharp edges a1 and a3 are formed during this step.

[0078] Through these grinding steps, the first connecting chamfer 28e and the second connecting chamfer 28f of the bushing are truncated. The sharp edge a1 is positioned relative to the center C of the first radius 28e1 and the second radius 28e2 of the first connecting chamfer. 28e1 C 28e2 Offset axially outward (i.e., towards the front 28c).

[0079] The sharp edge a2 is relative to the center C of the first radius 28e1 and the second radius 28e2 of the first connecting chamfer. 28e1 C 28e2 It is offset radially outward (i.e., towards the outer surface 28a).

[0080] In the same manner, the sharp edge a3 is positioned relative to the center C of the first radius 28f1 and the second radius 28f2 of the second connecting chamfer. 28f1 C 28f2 The sharp edge a4 is offset outward in the axial direction (i.e., towards the front 28d) and the sharp edge a4 is offset outward in the radial direction (i.e., towards the outer surface 28a) relative to these centers.

[0081] After these grinding steps, the bushing 28 takes on its final shape and final dimensions.

[0082] The insulating insert 30 is made of an electrically insulating material. The insulating insert 30 may be made of, for example, a synthetic material (such as PEEK or PA46) or an elastomeric material (such as rubber).

[0083] The insulating insert 30 is radially positioned between the outer surface 14a of the outer ring and the hole 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 with respect to both the axial and circumferential directions. The insulating insert 30 also covers the grooves 22 and 24 in the outer ring. The insulating insert 30 also covers the hole 28b in the bushing. In this case, the insulating insert 30 also completely covers the hole 28b with respect to both the axial and circumferential directions.

[0084] As described above, in this case, the insulating insert 30 is overmolded onto the outer ring 14 of the bearing and the bushing 28. The insulating insert 30 is overmolded onto the outer surface 14a of the outer ring 14 and the hole 28b in the bushing 28.

[0085] The insulating insert 30 has an annular shape. The insulating insert 30 extends axially. The insulating insert 30 includes a cylindrical axial outer surface 30a, a cylindrical hole 30b radially opposite to the outer surface 30a, and two opposing radial faces 30c, 30d defining the hole and the outer surface axially. The radial faces 30c, 30d define the axial length of the insulating insert 30. The outer surface 30a and the hole 30b define the radial thickness of the insulating insert 30. The outer surface 30a radially contacts the hole 28b in the bushing. The hole 30b radially contacts the outer surface 14a of the outer ring and the grooves 22, 24. The hole 30b has a stepped shape.

[0086] In the exemplary embodiment shown, the outer ring, insulating insert, and bushing have coplanar surfaces 14c, 30c, 28c and 14d, 30d, 28d.

[0087] Alternatively, other configurations can be provided. For example, the insulating insert 30 can have a smaller axial dimension and be axially set back from the outer ring faces 14c, 14d. Alternatively, the insulating insert 30 can have a larger axial dimension and project axially from the outer ring faces 14c, 14d. In this case, the insulating insert 30 can at least partially cover these faces 14c, 14d. In a variation, the insulating insert 30 can at least partially cover the bushing faces 28c, 28d.

[0088] In another alternative or combination, the bushing 28 may protrude axially from the insulating insert 30 relative to the faces 30c and 30d, or retract axially from these faces.

[0089] In the exemplary embodiment shown, the first ring 12 of the bearing is the inner ring, and the second ring 14 to which the insulating insert 30 is fastened is the outer ring.

[0090] Alternatively, a reverse arrangement can be provided, where the insulating insert 30 is fastened to its second ring 14, which 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 radially positioned between the bore 12a in the inner ring and the outer surface of the bushing. The insulating insert is fastened to the inner ring and at least to the outer surface of the bushing. The bore in the bushing defines a bore in the bearing assembly. In this case, one or more connecting chamfers connect the front side of the bushing to the bore.

[0091] In the described exemplary embodiment, the bearing of the device is provided with a single row of rolling elements. In a variation, the bearing may be provided with several 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 sliding bearing without rolling elements.

Claims

1. A bearing assembly comprising a bearing (10) and an insulating sleeve (26), the bearing (10) having a first ring (12) and a second ring (14) rotatable relative to each other, the insulating sleeve (26) being mounted on the second ring (14) of the bearing and having a bushing (28) and an insulating insert (30), the insulating insert (30) being radially located between the second ring (14) and the bushing (28) and being made of an electrically insulating material, the bushing having a cylindrical outer surface (28a) defining the radial thickness of the bushing and a cylindrical inner surface (28b) on opposite sides of the outer surface, and a first front face (28c) and a second front face (28d) defining the axial length of the bushing, the insulating insert (30) being fastened to the second ring (14) of the bearing and at least to one of the outer and inner surfaces of the bushing (28), characterized in that, A first connecting chamfer (28e) connects a first front face (28c) of the bushing to the other surface of the outer and inner surfaces of the bushing (28). The first connecting chamfer (28e) is provided with a first concave radius (28e1), a second concave radius (28e2), and a truncated conical surface (28e3) extending between the first concave radius (28e1) and the second concave radius (28e2). The first concave radius (28e1) connects to the other surface of the bushing (28) while forming a sharp edge (a1), and the second concave radius (28e2) connects to the first front face (28c) while forming another sharp edge (a2).

2. The apparatus according to claim 1, characterized in that, The first concave radius (28e1) and the second concave radius (28e2) of the first connecting chamfer have different centers.

3. The apparatus according to claim 1 or 2, characterized in that, 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. The apparatus according to any one of the preceding claims, characterized in that, The second connecting chamfer (28f) connects the second front surface (28d) of the bushing to the other surface of the bushing (28). The second connecting chamfer (28f) is provided with a first concave radius (28f1), a second concave radius (28f2), and a truncated conical surface (28f3) extending between the first concave radius (28f1) and the second concave radius (28f2). The first concave radius (28f1) connects to the other surface of the bushing (28) while forming a sharp edge (a3), and the second concave radius (28f2) connects to the second front surface (28d) while forming another sharp edge (a4).

5. The apparatus according to claim 4, characterized in that, The first concave radius (28f1) and the second concave radius (28f2) of the second connecting chamfer have different centers.

6. The apparatus according to claim 4 or 5, characterized in that, 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. The apparatus according to any one of the preceding claims, characterized in that, The bushing (28) is made of metal.

8. The apparatus according to claim 7, characterized in that, The bushing (28) is obtained by pressing or machining.

9. A method for manufacturing a bushing for a bearing assembly according to any one of the preceding claims, the method comprising the following sequential steps: - The step of producing bushing blanks, which imparts the basic geometry of the bushing. - A heat treatment step to impart the required hardness to the bushing blank. - The step of radially grinding a portion of the first front surface (28c) and the second concave radius (28e2) of the first connecting chamfer adjacent to the first front surface of the bushing blank, and - The step of grinding the other surface of the bushing blank and a portion of the first concave radius (28e1) of the first connecting chamfer adjacent to the other surface in the axial direction.

10. An electric motor comprising a housing, a shaft, and at least one bearing assembly according to any one of claims 1 to 8, the at least one bearing assembly being radially mounted between the housing and the shaft.

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