Bearing arrangement with integrated electrical insulation for a motor or electric machine

Abstract

The bearing device (10) comprises a bearing provided with a first ring (12) and a second ring (14) and an insulating sleeve (26) fitted on the second ring and provided with a bushing (28) and an insulating liner (30) radially interposed between the second ring and the bushing (28), the liner (30) being made of electrically insulating material and overmoulded on the second ring (14) and at least on one of the outer surface (28a) and the inner surface (28b) of the bushing. The bushing (28) comprises two distinct parts (32, 34), each comprising an axial portion (32a, 34a) axially in contact with each other in a junction zone (48) and together defining the outer surface (28a) and the inner surface (28b). The axial portions (32a, 34a) form, in the junction zone (48), an annular groove (46) radially open on the side opposite the liner (30).

Description

Technical Field

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

[0002] In a motor or electric machine, at least one roller bearing is mounted between the housing and the rotating shaft to support the shaft and provide precise guidance for its rotation.

[0003] During operation, the mechanical forces and thermal stresses applied to the bearing can cause localized deformation, especially at the assembly interfaces between the bearing's components. This deformation can lead to excessive clearance, alignment defects, or premature wear, thus affecting the bearing's performance and service life.

[0004] To improve the robustness of bearings and limit these undesirable effects, it is known to provide an insulating sleeve for the outer ring of the bearing. The insulating sleeve consists of a bushing made of two parts and an insulating lining located radially between the outer ring and the bushing.

[0005] This solution provides effective electrical insulation and limits current transmission through the components of the bearing, thus reducing the risk of damage to the raceways and rolling elements.

[0006] However, assembling the bearing assembly inside the orifice of the motor housing may be problematic.

[0007] This is because during the assembly of the bearing assembly into the bore of the motor housing, the first component of the bushing is compressed through contact with the bore of the motor housing. Consequently, the free edge of the second component of the bushing protrudes radially outward, and as the user continues to push the bearing assembly axially into the bore of the motor housing, the free edge of the second component of the bushing may jam against the bore of the motor housing.

[0008] This can make assembling the bearing assembly difficult and can also lead to localized stress concentrations in the joint area between the two parts of the bushing.

[0009] Therefore, the present invention aims to overcome the above-mentioned disadvantages. Summary of the Invention

[0010] The present invention relates to a bearing assembly comprising a first and a second ring rotatable relative to each other, and an insulating sleeve fitted onto the second ring of the bearing and provided with a bushing and an insulating lining, the insulating lining being radially positioned between the second ring and the bushing and being made of an electrically insulating material.

[0011] According to a general feature, the bushing includes an outer surface defining the radial thickness of the bushing and an inner surface opposite the outer surface, the insulating lining being overmolded on the second ring of the bearing, and being overmolded on at least one of the outer and inner surfaces of the bushing.

[0012] According to another general feature, the bushing is made of two different parts, each part including at least one axial portion, the axial portions of the two parts of the bushing being axially in contact with each other in a joint zone, and together defining the outer and inner surfaces of the bushing.

[0013] According to another general feature, the axial portions of the two components of the bushing together define an annular groove in the mating area between the axial portions, the annular groove being radially open on the side opposite to the insulating liner.

[0014] Therefore, by preventing the formation of sharp edges in the joint area between the axial portions of the two bushing components during assembly, the assembly of the bearing assembly into the bore of the associated motor housing is facilitated. This reduces the risk of localized stress concentration in the joint area between the two bushing components during bearing assembly.

[0015] Preferably, each axial portion of the two components of the bushing is provided with a front face, an outer surface or inner surface that partially defines the other of the inner and outer surfaces of the bushing, and a profiled part extending between the outer or inner surface and the front face, the front faces of the axial portions of the two components being axially in contact with each other, and the profiled parts of the axial portions together defining the groove.

[0016] According to the first design, the profile of each axial portion of the two components of the bushing includes a bevel inclined relative to the axis of the bushing.

[0017] According to the second design, the profile of each axial portion of the two components of the bushing includes a convex section.

[0018] According to the third design, the profile of each axial portion of the two components of the bushing includes a cylindrical surface connected to the front side and a truncated conical surface that widens out from the cylindrical surface and connects to the outer or inner surface.

[0019] The two components of the bushing are advantageously symmetrical with respect to the radial mid-plane of the bearing assembly.

[0020] In one particular embodiment, each component includes a radial collar that extends radially from the axial portion toward the second turn.

[0021] The present invention also relates to a method for manufacturing a bearing device as defined above, the method comprising:

[0022] - The step of assembling one of the components of the bushing into the bottom of the manufacturing mold.

[0023] - The step of placing the second ring inside the manufacturing mold.

[0024] - The step of assembling another component of the bushing inside the manufacturing mold.

[0025] - The step of overmolding the insulating liner onto the second ring and at least overmolding it onto the annular outer surface of the bushing.

[0026] - The step of extracting the unitary assembly formed by the second ring, the first and second components of the bushing, and the insulating liner from the manufacturing mold, and

[0027] - The step of assembling the assembly formed by the second ring, the bushing components, and the insulating liner with the first ring of the bearing.

[0028] Prior to the step of assembling the components of the bushing, the outline of each axial portion of the two components of the bushing can be formed by stamping.

[0029] The present invention also relates to an electric motor comprising a housing, a shaft, and at least one bearing assembly as defined above, the at least one bearing assembly being radially located between the housing and the shaft. Attached Figure Description

[0030] The invention will be better understood by reading the detailed description of embodiments given by way of non-limiting example and illustrated in the accompanying drawings, in which:

[0031] Figure 1 This is a half-view of the axial section of a bearing device according to an exemplary embodiment of the present invention.

[0032] Figure 2 yes Figure 1 A partially exploded perspective view of the bearing assembly, wherein the insulating lining of the assembly is not shown.

[0033] Figure 3 , Figure 4 and Figure 5 These are detailed views of a bearing assembly according to another exemplary embodiment of the present invention, and

[0034] Figure 6 It shows the manufacturing process. Figure 1 A flowchart of the method for assembling the bearing device. Detailed Implementation

[0035] Figure 1 and Figure 2 The bearing assembly shown 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 exemplary embodiment shown, the first ring 12 is the inner ring of the bearing, and the second ring 14 is the outer ring.

[0036] 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.

[0037] In the exemplary embodiment shown, the bearing 10 also includes a row of rolling elements 16, here 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 uniform circumferential spacing of the rolling elements 16. The bearing 10 may also be provided with seals or sealing flanges.

[0038] The inner ring 12 includes a cylindrical orifice 12a, a cylindrical axial outer surface 12b opposite the orifice in the radial direction, and two opposing radial faces (not numbered) defining the orifice and the outer surface in the axial direction. The orifice 12a and the outer surface 12b define the radial thickness of the inner ring 12. The orifice 12a forms the inner surface of the inner ring.

[0039] The inner ring 12 also includes an inner raceway 18 formed on the outer surface 12b for the rolling element 16. The raceway 18 faces outward in the radial direction.

[0040] The outer ring 14 includes a cylindrical axial outer surface 14a, a cylindrical aperture 14b radially opposite to the outer surface 14a, and two opposing radial faces 14c, 14d defining the aperture axially. The outer surface 14a and the aperture 14b define the radial thickness of the outer ring 14.

[0041] In the exemplary embodiment shown, the outer surface 14a of the ring has two different diameters. Alternatively, the outer surface 14a may have a single diameter.

[0042] The outer ring 14 also includes an outer raceway 20 formed on the orifice 14b for the rolling element 16. The raceway 20 faces inward in the radial direction.

[0043] 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 rigidly connected to the outer ring 14.

[0044] The insulating sleeve 26 includes a bushing 28 and an insulating liner 30 radially positioned between the outer ring 14 and the bushing 28. The insulating liner 30 is overmolded onto the outer ring 14 and the bushing 28.

[0045] Bushing 28 is annular and consists of two distinct, separate components 32, 34, which form half-flanges that are axially in contact with each other. In the exemplary embodiment shown, components 32, 34 of the bushing are identical and symmetrical with respect to the radial midplane to reduce manufacturing costs. Alternatively, asymmetrical components 32, 34 are of course conceivable. In another variation, bushing 28 may consist of more than two components. Preferably, components 32, 34 of bushing 28 are made of steel. Components 32, 34 can advantageously be obtained from sheet metal blanks by cutting, stamping, and rolling. Alternatively, components 32, 34 can be obtained from tubes or from forged and / or rolled blanks, using methods such as sintering or stamping, or by machining (especially when precise and / or complex shapes are required).

[0046] Each component 32, 34 of the bushing includes annular axial portions 32a, 34a and radial collars 32b, 34b extending radially inward from the axial portions 32a, 34a. The axial portions 32a, 34a are in axial contact with each other. The radial collars 32b, 34b extend from the axial ends of the axial portions 32a, 34a located axially outside the device. In the exemplary embodiment shown, the radial collars 32b, 34b are annular. Alternatively, at least one of the radial collars 32b, 34b may take the form of sectors spaced apart from each other in the circumferential direction.

[0047] The bushing 28 includes a cylindrical axial outer surface 28a and a cylindrical orifice 28b that is radially opposite to the outer surface 28a. The axis 25 of the cylindrical orifice 28b is coaxial with the axis X-X'.

[0048] The orifice 28b forms the inner surface of the bushing 28. The axial portions 32a and 34a of the bushing 28 together define the outer surface 28a. Similarly, the axial portions 32a and 34a of the components together define the orifice 28b.

[0049] The outer surface 28a and the orifice 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.

[0050] Bushing 28 also includes two opposing radial faces 28c, 28d that define an outer surface 28a in the axial direction. Faces 28c, 28d define the axial length of the bushing. Face 28c is defined by a radial collar 32b, and face 28d is defined by a radial collar 34b. More specifically, face 28c is defined by the outer side of the radial collar 32b, and face 28d is defined by the outer side of the radial collar 34b.

[0051] 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 are conceivable. 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.

[0052] In the exemplary embodiment shown, the radial collars 32b, 34b of the bushing components extend radially beyond the outer surface 14a of the outer ring, i.e., they protrude radially inward relative to the outer surface 14a. In other words, the free ends of the radial collars 32b, 34b are radially offset inward relative to the outer surface 14a of the outer ring. The radial collars 32b, 34b remain at a distance from the inner ring 12. Alternatively, the radial collars 32b, 34b may have a radial dimension. In another variation, at least one of the two components of the bushing may be without radial collars.

[0053] As described above, the axial portions 32a and 34a of the two components of the bushing are in axial contact with each other. Each axial portion 32a and 34a has a face 32c and 34c at its free end. Each face 32a and 34a, together with the face 28c and 28d of the radial collars 32b and 34b, defines the axial length of the associated component of the bushing. The face 32c of the axial portion 32a is in axial contact with the face 34c of the axial portion 34a in the joint zone 48 between the axial portions 32a and 34a of the two components of the bushing.

[0054] Each axial portion 32a, 34a is further provided with an outer surface and an inner surface (not numbered), and profiled parts 4a, 44b extending between the outer surface and the front surfaces 32c, 34c. The profiled parts 44a, 44b of each axial portion 32a, 34a connect the outer surface of the axial portion 32a, 34a to the front surfaces 32c, 34c. The inner surfaces of the axial portions 32a, 34a together define the orifice 28b of the bushing. The outer surfaces of the axial portions 32a, 34a and the profiled parts 44a, 44b together define the outer surface 28a of the bushing.

[0055] The axial portions 32a and 34a of the two components of the bushing together define a groove 46 in the mating area 48 between the axial portions 32a and 34a. More specifically, the contour portions 44a and 44b together define the groove 46. The groove 46 opens radially on the side opposite to the insulating liner 30, that is, it opens radially on the outer side.

[0056] exist Figure 3 In the exemplary embodiment shown, each profile portion 44a, 44b is provided with a truncated conical bevel 50a, 50b that is directly connected to the outer surface of the axial portions 32a, 34a and the front surfaces 32c, 34c. Each bevel 50a, 50b is inclined relative to the axis of the bushing.

[0057] As a variation, the axial portions 44a, 44b of the two components of the bushing can have other configurations. For example, in Figure 4 In the exemplary embodiment shown (where the same elements have the same reference numerals), each profile portion 44a, 44b is provided with a convex section 52a, 52b that is directly connected to the outer surface of the axial portion 32a, 34a and the front surface 32c, 34c.

[0058] exist Figure 5 In another variation shown (where the same elements have the same reference numerals), each profile portion 44a, 44b of the axial portion of the two components of the bushing is provided with cylindrical surfaces 60a, 60b connected to the front surfaces 32c, 34c, and flared frustoconical surfaces 62a, 62b that widen out from the cylindrical surfaces 60a, 60b and connect to the outer surfaces of the axial portions 32a, 34a.

[0059] The insulating liner 30 is radially positioned between the outer surface 14a of the outer ring and the orifice 28b of the bushing. The insulating liner 30 covers the outer surface 14a of the outer ring. Here, the insulating liner 30 completely covers the outer surface 14a in both the axial and circumferential directions.

[0060] The insulating liner 30 also covers the orifice 28b of the bushing 28. Here, the insulating liner 30 also completely covers the orifice 28b in both the axial and circumferential directions. The insulating liner 30 covers the orifices of the axial portions 32a, 34a of each component 32, 34 of the bushing.

[0061] The insulating liner 30 also covers the inner surfaces of the radial collars 32b, 34b of each component 32, 34 of the bushing and the free ends of the radial collars 32b, 34b of each component 32, 34 of the bushing 28.

[0062] The insulating liner 30 is annular. The insulating liner 30 extends axially. The insulating liner 30 includes a cylindrical axial outer surface 30a, a cylindrical aperture 30b radially opposite the outer surface 30a, and two opposing radial faces 30c, 30d defining the aperture and the outer surface axially. The radial faces 30c, 30d define the insulating liner 30 axially. The outer surface 30a and the aperture 30b define the radial thickness of the insulating liner 30. The outer surface 30a radially contacts the aperture 28b of the bushing. The outer surface 30a also radially contacts the free ends of the radial collars 32b, 34b of each component 32, 34 of the bushing. The outer surface 30a has a stepped shape. The aperture 30b radially contacts the outer surface 14a of the outer ring. The aperture 30b has a stepped shape.

[0063] In the illustrated embodiment, the outer ring, insulating liner, and bushing have coplanar surfaces 14c, 30c, 28c and 14d, 30d, 28d.

[0064] The insulating liner 30 also includes two ribs 40, 42, which extend radially outward from the outer surface 30a, and each rib extends within a groove 36, 38 in an orifice formed in the axial portions 32a, 34a of the bushing components 32, 34. Each rib 40, 42 extends projectingly from the outer surface 30a of the insulating liner. Each rib 40, 42 is formed on the outer surface 30a during the overmolding of the insulating liner 30.

[0065] 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 an elastomeric material (such as rubber).

[0066] To manufacture the bearing assembly 10, the following steps are performed.

[0067] exist Figure 6 In the first step 70, which is schematically shown, the first component 32 of the bushing is assembled inside the mold provided for covering the molded insulating liner 30.

[0068] In the second step 72, the outer ring 14 is placed inside the mold.

[0069] Then, in the third step 74, the second part 34 of the bushing is assembled inside the mold and axially contacts the first part 32. In this position assembled inside the mold, the first part 32 and the second part 34 of the bushing are radially separated from the outer ring 14 by a certain distance. The first part 32 and the second part 34 of the bushing are formed by stamping before being assembled inside the manufacturing mold.

[0070] Then, in the next step 76, the insulating liner 30 is overmolded onto the first component 32 and the second component 34 of the outer ring 14 and the bushing 28. Ribs 40, 42 of the insulating liner 30 are formed in this step.

[0071] In the fifth consecutive step 78, the unitary assembly formed by the outer ring 14, the first component 32 and the second component 34 of the bushing 28, and the insulating liner 30 is extracted from the mold.

[0072] Then, in the sixth step 80, the integral assembly formed by the outer ring 14, the first component 32 and the second component 34 of the bushing 28 and the insulating liner 30 is assembled with the row of rolling members 16, the cage 17 and the inner ring 12.

[0073] In the exemplary embodiment shown, the first ring 12 of the bearing is the inner ring, and the second ring 14, on which the insulating liner 30 is overmolded, is the outer ring.

[0074] As an alternative, a reverse configuration can be envisioned, where the second ring 14 overmolded thereon is the inner ring. In this case, the insulating sleeve 26 is located in the orifice 12a of the inner ring. Thus, the insulating liner 30 is radially positioned between the orifice 12a of the inner ring and the outer surface of the bushing 28. The insulating liner 30 is overmolded on the inner ring and at least overmolded on the outer surface of the bushing 28. The orifice of the bushing 28 defines the orifice 28b of the bearing assembly 10. In this variation, the groove defined in the mating area between the two parts 32, 34 of the bushing opens radially inward and is therefore held radially open on the side opposite to the insulating liner 30.

[0075] In the described exemplary embodiment, the bearing of device 10 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 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 (10) comprising a bearing and an insulating sleeve (26), the bearing having a first ring (12) and a second ring (14) rotatable relative to each other, the insulating sleeve (26) being fitted onto 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 (28) comprising an outer surface (28a) defining the radial thickness of the bushing and an inner surface (28b) opposite to the outer surface (28a), the insulating liner (30) being overmolded onto the second ring (14) of the bearing and being overmolded onto at least one of the outer surface (28a) and the inner surface (28b) of the bushing, characterized in that, The bushing (28) is made of two different parts (32, 34), each part including at least one axial portion (32a, 34a), the axial portions (32a, 34a) of the two parts of the bushing are axially in contact with each other in a mating area (48) and together define the outer surface (28a) and inner surface (28b) of the bushing (28), and the axial portions (32a, 34a) of the two parts (32, 34) of the bushing together define a groove (46) in the mating area (48) between the axial portions (32a, 34a), the groove (46) opening radially on the side opposite to the insulating lining (30).

2. The apparatus according to claim 1, characterized in that, Each axial portion (32a, 34a) of the two components (32, 34) of the bushing (28) is provided with a front surface (32c, 34c), an outer or inner surface (28a, 28b) that partially defines another surface of the surfaces (28a, 28b) of the bushing (28), and a contour portion (44a, 44b) extending between the outer or inner surface and the front surface (32c, 34c). The front surfaces (32c, 34c) of the axial portions (32a, 34a) of the two components (32, 34) are in axial contact with each other, and the contour portions (44a, 44b) of the axial portions (32a, 34a) together define the groove (46).

3. The apparatus according to claim 2, characterized in that, The profile portion (44a, 44b) of each axial portion (32a, 34a) of the two components (32, 34) of the bushing (28) includes a slope (50a, 50b) inclined relative to the axis (X-X') of the bushing.

4. The apparatus according to claim 2, characterized in that, The profile portion (44a, 44b) of each axial portion (32a, 34a) of the two components (32, 34) of the bushing (28) includes a convex section (52a, 52b).

5. The apparatus according to claim 2, characterized in that, The profile portion (44a, 44b) of each axial portion (32a, 34a) of the two components (32, 34) of the bushing (28) includes a cylindrical surface (60a, 60b) connected to the front surface (32c, 34c) of the axial portion (32a, 34a) and a flared truncated conical surface (62a, 62b) that widens from the cylindrical surface (60a, 60b) and connects to the outer or inner surface.

6. The apparatus according to any one of claims 1 to 5, characterized in that, The two components (32, 34) of the bushing (28) are symmetrical with respect to the radial midplane of the bearing assembly (10).

7. A method for manufacturing a bearing device according to any one of claims 1 to 6, comprising: - Step (70) of assembling one of the components (32, 34) of the bushing (28) into the bottom of the manufacturing mold. - Step (72) of placing the second ring (14) inside the manufacturing mold. - Step (74) of assembling another component of the bushing (28) of the components (32, 34) inside the manufacturing mold. - Step (76) of overmolding the insulating liner (30) onto the second ring (14) and at least overmolding it onto the outer surface (28a) of the bushing (28). - The step (78) of removing the integral assembly formed by the second ring (14), the first part (32) and the second part (34) of the bushing (28) and the insulating liner (30) from the manufacturing mold, and - Step (80) of assembling the assembly formed by the second ring (14), the components (32, 34) of the bushing (28) and the insulating liner (30) with the first ring (12) of the bearing.

8. The manufacturing method according to claim 7, characterized in that, Before step (70) of assembling the components (32, 34) of the bushing (28), the contour portions (44a, 44b) of each axial portion (32a, 34a) of the two components (32, 34) of the bushing (28) are formed by stamping.

9. An electric motor comprising a housing, a shaft, and at least one bearing device (10) according to any one of claims 1 to 6, said at least one bearing device (10) being radially located between the housing and the shaft.

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