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

Abstract

The invention relates to a bearing device, in particular for an electric motor or an electric machine, incorporating an electrically insulating bearing device. The device comprises a bearing (10) provided with a first ring (12) and a second ring (14). The device comprises an insulating sleeve (26) fitted on the second ring (14) and provided with a bushing (28) and an insulating liner (30). An insulating liner is fixed on the second ring (14) and on at least one of an outer surface and an inner surface 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 radius connected to the first front face forming a sharp edge and a spherical surface connected to the outer surface forming another sharp edge and connected to the radius.

Description

Technical Field

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

[0002] In an electric motor or electric machine, at least one roller bearing is fitted between the housing of the electric motor or electric machine 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 a motor or electric machine, which generates a current between the inner ring (integrated with the shaft) and the outer ring (integrated with the housing) of the roller bearing.

[0004] Current flowing through the components of a roller bearing can damage these components, particularly the rolling elements and the raceways on the inner and outer rings. Discharge can also generate vibration.

[0005] To eliminate these drawbacks, it is known to replace the rolling elements of bearings made of the same steel as the inner and outer rings with rolling elements made of ceramic. Thus, they are commonly referred to as hybrid roller bearings.

[0006] However, this type of hybrid roller bearing is relatively expensive.

[0007] To eliminate the aforementioned drawbacks, it is also known to equip the outer ring of a roller bearing with an insulating sleeve, which is provided with a bushing and an insulating lining, the insulating lining being made of an electrically insulating material located radially between the outer ring and the bushing.

[0008] When the bearing assembly is installed inside the motor housing, or when the bearing assembly is disassembled, the housing bore may be damaged.

[0009] The purpose of this invention is to eliminate this drawback. 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 insulation sleeve mounted on the second ring of the bearing. The insulation sleeve has a bushing and an insulation lining, the insulation lining being radially positioned between the second ring of the bearing and the bushing. The insulation lining is made of an electrically insulating material.

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

[0013] The insulating liner is fixed 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 connection chamfer connects the first front face of the bushing to the other surface of the bushing, which is either the outer surface or the inner surface.

[0015] The first connecting chamfer is provided with a radius that connects to the first front surface and forms a sharp edge, and a spherical surface that connects to the other surface of the bushing, forms another sharp edge, and connects to the radius.

[0016] The radius of the spherical surface increases (or grows) in the direction of the other surface of the bushing.

[0017] Therefore, a bearing assembly incorporating electrical insulation has been obtained, which is more economical than conventional hybrid roller bearings.

[0018] In addition, given the presence of a first connecting chamfer with a truncated form, the device is easily assembled into a motor or associated electric machine without the risk of damaging the rotor or the hole of the electric machine.

[0019] Each sharp edge forms a change of slope between the first connecting chamfer and the first front surface of the bushing or between the first connecting chamfer and the other surface of the bushing.

[0020] The spherical surface of the first connecting chamfer reduces the projecting nature of the sharp edge between the first connecting chamfer and the other surface of the bushing.

[0021] Preferably, the spherical surface of the first connecting chamfer is tangentially connected to the radius.

[0022] The radius of the spherical surface of the first connecting chamfer is advantageously greater than the radius of the first chamfer.

[0023] Advantageously, a second connecting chamfer connects the second front surface of the bushing to the other surface of the bushing. The second connecting chamfer has a radius that connects to the second front surface and forms a sharp edge, and a spherical surface that connects to the other surface of the bushing, forms another sharp edge, and connects to the radius. The radius of the spherical surface increases in the direction of the other surface of the bushing.

[0024] Preferably, the spherical surface of the second connecting chamfer is tangentially connected to the radius.

[0025] The radius of the spherical surface of the second connecting chamfer is advantageously greater than the radius of the second chamfer.

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

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

[0028] If the insulating lining is made of synthetic or elastomeric materials, this can make the device insensitive to temperature changes.

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

[0030] "Axial direction" refers to the direction parallel to the axis of the bearing assembly.

[0031] "Circumferential direction" refers to the direction perpendicular to the axial direction and the radius of the bearing assembly; in other words, it is tangent to the 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 the second alternative 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 positioned 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 base, a shaft, and at least one bearing assembly as defined above, the at least one bearing assembly being radially mounted between the base and the shaft.

[0036] The present invention also relates to a method for producing bushings for bearing devices as defined above, the method comprising the following sequential steps:

[0037] - The step of producing a bush blank, providing the bush blank with the basic geometry of the bush blank, wherein the other surface of the bush blank has a spherical form;

[0038] - A heat treatment step to provide the required hardness to the bushing blank;

[0039] - The step of radially straightening / rectifying the bushing on the first front surface and the portion of the first connecting chamfer adjacent to the first front surface; and

[0040] - The step of axially straightening the other surface of the bushing blank to provide the bushing blank with a cylindrical form, wherein the spherical surface of the first connecting chamfer remains unrectified. Attached Figure Description

[0041] The invention will be better understood by studying the detailed description of the embodiments given by way of non-limiting example and illustrated in the accompanying drawings, in which:

[0042] Figure 1 This is a half-view of a cross-section of a bearing device according to an embodiment of the present invention;

[0043] Figure 2 and Figure 3 yes Figure 1 Detailed view of the bushing of the device;

[0044] Figure 4 and Figure 5 yes Figure 1 Detailed view of the bushing of the device before the rectification step;

[0045] Figure 6This is a half-view of the axial section of a bearing device according to another embodiment of the present invention;

[0046] Figure 7 This is a half-view of the axial section of a bearing device according to yet another embodiment of the present invention; and

[0047] Figure 8 and Figure 9 yes Figure 7 Detailed view of the bushing of the device. Detailed Implementation

[0048] 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 embodiment, the first ring 12 is the inner ring of the bearing, and the second ring 14 is the outer ring.

[0049] The bearing assembly is designed not to conduct current. The bearing assembly incorporates electrical insulation.

[0050] 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.

[0051] In the illustrated embodiment, the bearing 10 further 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 sealing flanges.

[0052] The inner ring includes a cylindrical bore 12a, a cylindrical axial outer surface 12b radially opposite the bore, and two opposing radial faces (not referenced in the figures) defining the bore and the outer surface axially. 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.

[0053] 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.

[0054] The outer ring 14 includes a cylindrical axial outer surface 14a, a cylindrical bore 14b radially opposite the outer surface 14a, and two opposing radial faces 14c, 14d defining the outer surface and the bore axially. The outer surface 14a and the bore 14b define the radial thickness of the outer ring 14. In this case, the outer surface 14a has a stepped form. Alternatively, the outer surface 14a may have a single diameter.

[0055] The outer ring 14 also includes an outer raceway 24 formed on the bore 14b for the rolling element 16. The raceway 20 points radially inward.

[0056] 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 integral with the outer ring 14.

[0057] The insulating sleeve 26 includes a bushing 28 and an insulating liner 30 radially positioned between the outer ring 14 and the bushing 28. In this case, the insulating liner is overmolded onto the outer ring 14 and the bushing 28.

[0058] Bushing 28 has an annular form. Bushing 28, with an axis X-X', extends axially. Bushing 28 is composed of two distinct parts 32, 34. These two separate parts 32, 34 form a half-flange, which in this case supports each other axially against each other. In the illustrated embodiment, the parts 32, 34 of the bushing are identical and symmetrical with respect to the median radial plane of the device to reduce production costs. Alternatively, asymmetrical parts 32, 34 can be provided. In another variation, bushing 28 may be composed of more than two parts. Preferably, the parts 32, 34 of bushing 28 are made of steel. Parts 32, 34 can advantageously be obtained from sheet metal by cutting, stamping, and rolling. As an alternative, components 32 and 34 can be obtained from tubes or from forged and / or rolled blanks, or they can also be obtained by sintering and pressing.

[0059] Each component 32, 34 of the bushing includes annular axial portions 32a, 34a and annular radial flanges 32b, 34b extending radially inward from the axial portions. The axial portions 32a, 34b support each other axially. The radial flanges 32b, 34b extend from the axial ends of the axial portions 32a, 34a located axially outside the device. In the illustrated embodiment, the radial flanges 32b, 34b are annular.

[0060] The bushing 28 includes a cylindrical axial outer surface 28a and a cylindrical bore 28b radially opposite the outer surface 28a, the axis of which is coaxial with axis X-X'. The bore 28b forms the inner surface of the bushing 28. The bore 28b is radially oriented inward, i.e., oriented on one side of the outer ring 14 and the insulating liner 30. The axis of the bore 28b is coaxial with axis X-X'. Axial portions 32a and 34a of the bushing components collectively define the outer surface 28a. Similarly, axial portions 32a and 34a of the components collectively define the bore 28b. The outer surface 28a and the bore 28b define the radial thickness of the bushing 28. The outer surface 28a of the bushing forms 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] Bushing 28 also includes opposing first radial face 28c and second radial face 28d that define the outer surface 28a in the axial direction. Faces 28c and 28d define the axial length of the bushing. Face 28c is defined by a radial flange 32b, and face 28d is defined by a radial flange 34b. More specifically, face 28c is defined by the outer side of radial flange 32b, and face 28d is defined by the outer side of radial flange 34b.

[0062] In the illustrated embodiment, the frontal faces 28c and 28d of the bushing are coplanar with the frontal faces 14c and 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 remain axially recessed from or protrude from the faces 14c and 14d of the outer ring.

[0063] Bushing 28 also includes a first annular connecting chamfer 28e and a second annular connecting chamfer 28f, which respectively connect the front surfaces 28c and 28d to the outer surface 28a. The connecting chamfers 28e and 28f are symmetrical with respect to the median radial plane of the device.

[0064] like Figure 2 As shown, the first connecting chamfer 28e is provided with a convex radius 28e1 connected to the front face 28c and a spherical surface 28e2 connected to the outer surface 28a and the radius 28e1.

[0065] Radius 28e1 is directly connected to the front surface 28c. Spherical surface 28e2 is directly connected to the outer surface 28a. In other words, for radius 28e1, there is no additional surface between the first radius and the front surface 28c, and for spherical surface 28e2, there is no additional surface between the spherical surface and the outer surface 28a.

[0066] Radius 28e1 is connected to the front surface 28c by forming a sharp edge a1, and the spherical surface 28e2 is connected to the outer surface 28a by forming another sharp edge a2. The center of radius 28e1 is marked with reference numeral C. 28e1 Sharp edge a1 relative to center C 28e1 It is offset radially outward, that is, offset to one side of the outer surface 28a. The sharp edge a2 is relative to the center C. 28e1 It is offset radially inward.

[0067] The spherical surface 28e2 is tangentially connected to radius 28e1. The axial length of the spherical surface 28e2 is... Figure 2 The figure is referenced by L1. The spherical surface 28e2 widens in the direction of the outer surface 28a. In other words, the radius of the spherical surface 28e2 increases in the direction of the outer surface 28a. The radius of the spherical surface 28e2 is greater than the radius 28e1. The center of the spherical surface 28e2 (not shown) is located, for example, on the central radial plane of the bushing, on the outer side of the bushing.

[0068] In the same manner as the first connecting chamfer 28a, and as... Figure 3 As shown, the second connecting chamfer 28f is provided with a convex radius 28f1 connected to the front face 28d and a spherical surface 28f2 connected to the outer surface 28a and the radius 28f1.

[0069] Radius 28f1 is directly connected to the frontal face 28d. The spherical surface 28f2 is directly connected to the outer surface 28a. For radius 28f1, there is no additional surface between the first radius and the frontal face 28d, and for the spherical surface 28f2, there is no additional surface between the spherical surface and the outer surface 28a.

[0070] Radius 28f1 is connected to the positive surface 28d by forming a sharp edge a3, and the spherical surface 28f2 is connected to the outer surface 28a by forming another sharp edge a4. The center of radius 28f1 is marked with reference numeral C. 28f1Sharp edge a3 relative to center C 28f1 It is offset radially outward, that is, offset to one side of the outer surface 28a. The sharp edge a4 is relative to the center C. 28f1 Offset inwards along the axial direction.

[0071] A spherical surface 28f2 is tangentially connected to a radius 28f1. The axial length of the spherical surface 28f2 is... Figure 3 The figure is referenced by L2. The spherical surface 28e2 widens in the direction of the outer surface 28a. In other words, the radius of the spherical surface 28f2 increases in the direction of the outer surface 28a. The radius of the spherical surface 28f2 is greater than the radius 28f1. The center of the spherical surface 28f2 (not shown) is located, for example, on the central radial plane of the bushing, on the outer side of the bushing.

[0072] The following steps are required to produce bushing 28.

[0073] In the first step, blanks are provided for each component 32, 34 of the bushing, giving the blanks a basic geometry with a rough form of an outer surface 28a, a hole 28b, a front face 28c or 28d, and a connection chamfer 28e or 28f, such as... Figure 4 and Figure 5 As shown in the middle section. At this stage, the outer surface 28a of the bushing is not yet cylindrical, but spherical.

[0074] Then, in the second consecutive step, the blanks of the bushing components 32 and 34 are heat-treated to provide the blanks with the required hardness.

[0075] Next, in the third consecutive step, the frontal face 28c of the bushing blank and the portion of the first chamfer radius 28e1 adjacent to the frontal face 28c, as well as the frontal face 28d of the bushing blank and the portion of the second chamfer radius 28f1 adjacent to the frontal face 28d, are straightened in the radial direction. During this step, sharp edges a1 and a3 are formed.

[0076] During this third step, the outer surface 28a of the bushing blank is also straightened in the axial direction, such as by giving the bushing blank a cylindrical form. Sharp edges a2 and a4 are formed during this step. Spherical surfaces 28e2 and 28f2 are not straightened.

[0077] Through a straightening process, the first connecting chamfer 28e and the second connecting chamfer 28f of the bushing are truncated.

[0078] After these straightening steps, bushing 28 has its final form and its final dimensions.

[0079] The insulating liner 30 is made of an electrically insulating material. The insulating liner 30 may be made of, for example, a synthetic material (such as PEEK or PA46), or it may be made of an elastomeric material (such as rubber).

[0080] The insulating liner 30 is radially positioned between the outer surface 14a of the outer ring and the bore 28b of the bushing. The insulating liner 30 covers the outer surface 14a of the outer ring. In this case, taking into account both the axial and circumferential directions, the insulating liner 30 completely covers the outer surface 14a.

[0081] The insulating liner 30 also covers the bore 28b of the bushing. In this case, the insulating liner 30 also completely covers the bore 28b, taking into account both the axial and circumferential directions. The insulating liner 30 also covers the inner surfaces of the radial flanges 32b and 34b of each component 32, 34 of the bushing. The inner surface of each radial flange 32b and 34b and the outer surface opposite the inner surface in the axial direction define the axial thickness of the flange. For each radial flange 32b and 34b, the inner surface is oriented towards the interior of the device, and the outer surface is oriented towards the exterior of the device in the axial direction. The insulating liner 30 also covers the free ends of the radial flanges 32b and 34b of each component 32, 34 of the bushing.

[0082] The insulating liner 30 has an annular form (shape). The insulating liner 30 extends axially. The insulating liner 30 includes a cylindrical axial outer surface 30a, a cylindrical bore 30b radially opposite the outer surface 30a, and two opposing radial faces 30c, 30d defining the bore and the outer surface axially. The radial faces 30c, 30d define the axial length of the insulating liner 30. The outer surface 30a and the bore 30b define the radial thickness of the insulating liner 30. The outer surface 30a radially contacts the bore 28b of the bushing. The outer surface 30a also radially contacts the free ends of each radial flange 32b, 34b of the bushing. The outer surface 30a has a stepped form (shape). The bore 30b radially contacts the outer surface 14a of the outer ring. The bore 30b has a stepped form.

[0083] In the illustrated embodiment, the faces 14c, 30c, 28c and 14d, 30d, 28d of the outer ring, insulating liner and bushing are coplanar.

[0084] Alternatively, other configurations can be provided. For example, the insulating liner 30 can have a reduced axial dimension and remain axially recessed from the outer ring faces 14c, 14d. Alternatively, the insulating liner 30 can have an increased (or enlarged) axial dimension and extend axially projecting from the outer ring faces 14c, 14d. In this case, the insulating liner 30 can at least partially cover these faces 14c, 14d. As a variation, the insulating liner 30 can at least partially cover the bushing faces 28c, 28d.

[0085] In another alternative or combination, bushing 28 may extend axially overly from insulating bushing 30 opposite faces 30c and 30d, or bushing 28 may remain axially recessed from these faces.

[0086] Figure 6 The embodiment shown (where the same elements have the same reference numerals) differs from the first example in that the bushing 28 is a monolithic form. The bushing 28 is manufactured as a single piece. Thus, the bushing comprises a single axial portion 36 (instead of the two axial portions 32a, 34a in the first example) and two radial flanges 32b, 34b.

[0087] In this example, the radial dimension of the bushing flange 32b is larger than the radial dimension of the flange 34b. The bushing flanges 32b and 34b are symmetrical with respect to the intermediate radial plane of the device.

[0088] In the illustrated embodiment, flange 34b remains radially recessed relative to the large-diameter portion of the outer surface 14a of the outer ring. In other words, the free end of flange 34b is radially offset outward relative to this large-diameter portion of the outer surface 14a.

[0089] In the illustrated embodiment, the bushing flange 32b extends radially beyond the large-diameter portion of the outer surface 14a of the outer ring; that is, the bushing flange 32b protrudes radially inward relative to this large-diameter portion. In other words, the free end of the flange 32b is radially offset inward relative to the large-diameter portion of the outer surface 14a of the outer ring. The flanges 32b and 34b remain spaced apart from the outer ring 14.

[0090] Figures 7 to 9 The embodiment shown (where the same elements have the same reference numerals) differs from the second example in that the radial flanges 32b, 34b of the bushing have reduced radial dimensions. The radial flanges 32b, 34b remain radially recessed relative to the large-diameter portion of the outer surface 14a of the outer ring. In this case, the radial flanges 32b, 34b are symmetrical with respect to the intermediate radial plane ( / middle radial plane) of the device.

[0091] In this example, the axial length L1 of the first connected chamfered spherical surface 28e2 and the axial length L2 of the second connected chamfered spherical surface 28f2 are increased (or enlarged) relative to the other examples shown. The radii of the spherical surfaces 28e2 and 28f2 are smaller than the radii of the other examples shown.

[0092] In the illustrated embodiment, the first ring 12 of the bearing is the inner ring, and the second ring 14 on which the insulating liner 30 is fixed is the outer ring.

[0093] Alternatively, a reverse (or opposite) configuration can be provided, wherein the second ring 14, to which the insulating liner 30 is fixed, is the inner ring. In this case, the insulating sleeve is located in the bore 12a of the inner ring. Thus, the insulating liner is radially positioned between the bore 12a of the inner ring and the outer surface of the bushing. The insulating liner is fixed to the inner ring and at least to the outer surface of the bushing. The bore of the bushing defines the bore of the bearing assembly. In this case, one or more connecting chamfers connect the front side of the bushing to the bore.

[0094] In the described embodiment, the bearing of the device is provided with a single row of rolling elements. As a variation, the bearing may be provided with multiple rows of rolling elements. Additionally, roller bearings may include rolling element types other than balls, such as rollers. In another variation, the bearing may be a plain 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 liner (30), the insulating liner (30) being radially located between the second ring (14) and the bushing (28) and being made of an electrically insulating material, the bushing including a cylindrical outer surface (28a) defining the radial thickness of the bushing and a cylindrical inner surface (28b) opposite to the outer surface, and a first front face (28c) and a second front face (28d) defining the axial length of the bushing, the insulating liner (30) being fixed to the second ring (14) of the bearing and fixed to at least 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 another surface of the outer and inner surfaces of the bushing (28). The first connecting chamfer (28e) is provided with a radius (28e1) that connects to the first front face (28c) and forms a sharp edge (a1), and a spherical surface (28e2) that connects to the other surface of the bushing (28), forms another sharp edge (a2), and connects to the radius. The radius of the spherical surface (28e2) increases in the direction of the other surface of the bushing (28).

2. The apparatus according to claim 1, characterized in that, The spherical surface (28e2) of the first connecting chamfer (28e) is tangentially connected to the radius (28e1).

3. The apparatus according to claim 1 or 2, characterized in that, The radius of the spherical surface (28e2) of the first connecting chamfer (28e) is advantageously greater than the radius (28e1) of the first chamfer.

4. The apparatus according to any one of the preceding claims, characterized in that, The second connecting chamfer (28f) connects the second front face (28d) of the bushing to the other surface of the bushing (28). The second connecting chamfer (28f) is provided with a radius (28f1) that connects to the second front face (28d) and forms a sharp edge (a3), and a spherical surface (28f2) that connects to the other surface of the bushing (28), forms another sharp edge (a4), and connects to the radius. The radius of the spherical surface (28f2) increases in the direction of the other surface of the bushing (28).

5. The apparatus according to claim 4, characterized in that, The spherical surface (28f2) of the second connecting chamfer (28f) is tangentially connected to the radius (28f1).

6. The apparatus according to claim 4 or 5, characterized in that, The radius of the spherical surface (28f2) of the second connecting chamfer (28f) is greater than the radius (28f1) of the second chamfer.

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 stamping or machining.

9. A method for producing 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 includes providing the basic geometry of the bushing blanks, wherein the other surface of the bushing blanks has a spherical shape; - A heat treatment step to provide the required hardness to the bushing blank; - A step of radially straightening the bushing on the first front side (28c) and the portion of the radius (28e1) of the first connecting chamfer adjacent to the first front side; and - A step of axially straightening the other surface of the bushing blank to provide the bushing blank with a cylindrical shape, wherein the spherical surface (28e2) of the first connecting chamfer remains unstraightened.

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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