Bearing arrangement with integrated electrical insulation, in particular for electric machine or motor
By designing an insulating sleeve with a flange structure in the bearing assembly, the problems of current-damaged components and insulation inserts detaching in electric machinery are solved, realizing an economical and reliable electrically insulated bearing, reducing costs and improving mechanical strength.
Patent Information
- Application Number
- CN202510554397.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-05-06
- Filing Date
- 2025-04-29
- Publication Date
- 2025-11-11
AI Technical Summary
Rolling bearings in existing electric machines or motors may suffer from current damage to components and vibration during rotation. Hybrid rolling bearings are costly, and insulating inserts may detach from bushings during operation.
A bearing device is designed in which the bushing of the insulating sleeve has a flange structure, and the insulating insert is overmolded on the surface of the bushing. A firm connection is achieved by different radial dimensions and axial design of the flange to avoid relative movement between the insulating insert and the bushing. Synthetic or elastomer materials are used to reduce temperature sensitivity.
An integrated electrically insulated bearing device that is economical and easy to manufacture has been achieved, improving reliability and mechanical strength, preventing the insulation insert from detaching, and reducing costs.
Smart Images
Figure CN120926183A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of bearings, and particularly to bearings for use in electric motors, electric machines and related equipment. Background Technology
[0002] In an electric machine or motor, at least one rolling bearing is installed 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 an 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 a rolling bearing.
[0004] Current flowing through the components of a rolling bearing can damage these elements, particularly 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 the bearing, which are made of the same steel as the inner and outer rings, with rolling elements made of ceramic. 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, the insulating sleeve having a bush and an insulating insert made of electrically insulating material and located radially between the outer ring and the bush.
[0008] To secure the insulating insert to the outer ring and bushing without additional components or particular machining of the outer ring, the insulating insert can be overmolded.
[0009] However, with this solution, relative detachment of the insulating insert from the bushing may occur during operation.
[0010] Therefore, the present invention aims to overcome the above-mentioned disadvantages by providing a bearing device that is simple in design and economical. Summary of the Invention
[0011] 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.
[0012] The device further includes an insulating sleeve mounted on the second ring of the bearing. The insulating sleeve has an integral 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.
[0013] The term "one-piece bushing" means that the bushing is manufactured as a single unit. Bushings can be manufactured as individual pieces, or alternatively, as multiple pieces fastened together.
[0014] In other words, the bushing forms a single unit.
[0015] The bushing includes an outer surface defining the radial thickness of the bushing and an inner surface on the opposite side of the outer surface.
[0016] The insulating insert is overmolded on the second ring of the bearing and at least overmolded on one of the outer and inner surfaces of the bushing.
[0017] Based on its general characteristics, the bushing includes an axial portion and a first flange and a second flange, the axial portion defining the surface of the bushing over which the insulating insert is formed, the first flange and the second flange extending the axial portion radially toward the second ring.
[0018] According to another general feature, the insulating insert is also overmolded on the internal face of each of the first flange and the second flange.
[0019] According to another general feature, the radial dimension of the second flange is greater than the radial dimension of the first flange of the bushing.
[0020] The production of flanged bushings enables a secure connection with the insulating insert. This avoids the risk of relative movement between the insulating insert and the bushing in the axial direction, especially under temperature variations.
[0021] The term "axial direction" refers to the direction parallel to the axis of the bearing assembly.
[0022] Furthermore, providing flanges with different radial dimensions allows the bushing to exhibit good mechanical strength on the large flange side, while easily allowing axial mounting of the second ring or the entire bearing on the radially inner or radially outer side of the bushing on the small flange side.
[0023] This results in a bearing assembly with integrated electrical insulation, which is economical and easy to manufacture compared to conventional hybrid rolling bearings.
[0024] Preferably, the second flange of the bushing extends radially beyond the second ring and covers the outer or inner surface of the insulating insert.
[0025] With this configuration, when a significant axial load is applied to the device mounted inside the housing of an electric machine or motor (with the second flange bearing against the shoulder of the housing), the portion of the insulating insert located axially between the second ring and the second flange of the bushing is not subjected to shear stress. This is because compressive stress is applied to this portion of the insulating insert in this situation. This improves the reliability of the device.
[0026] Preferably, the first flange of the bushing is set back radially from the outer or inner surface of the second ring. Therefore, axial mounting of the second ring or the entire bearing relative to the bushing can be achieved via a simple axial push.
[0027] A first groove may be formed in the first frontal face of the second ring, and a second groove may be formed in the second frontal face of the second ring, the first groove and the second groove defining the outer or inner surface of the second ring in the axial direction.
[0028] The first flange of the bushing may be radially distanced from the first groove (at a distance), and the second flange may extend partially into the second groove.
[0029] The insulating insert may have two front sides that define the axial length of the insert.
[0030] According to the first design, at least one of the first flange and the second flange of the bushing is axially flush with one of the front faces of the insulating insert.
[0031] According to the second design, each of the first and second flanges of the bushing is axially flush with one of the front faces of the insulating insert.
[0032] Alternatively, one or each of the flanges of the bushing may be offset axially toward the inward or outward relative to the associated front side of the insulating insert.
[0033] According to a particular design, the surface of the bushing is provided with at least one slot extending in the circumferential direction, and the attachment rib of the insulating insert having a complementary shape extends within the slot.
[0034] Therefore, the axial attachment of the insulating insert to the bushing was further improved.
[0035] The term "circumferential direction" refers to a direction that is perpendicular to the axial direction and perpendicular to the radius of the bearing assembly; in other words, it is tangent to the circle whose center is on the axis of the bearing assembly.
[0036] If the insulating insert is made of synthetic or elastomeric materials, the device is less sensitive to temperature changes.
[0037] In one particular embodiment, the bushing is made of a metallic material. Therefore, the bushing can be easily machined to a predetermined radial tolerance. Advantageously, the bushing is obtained from sheet metal blanks by cutting, pressing, and roll bending.
[0038] In one embodiment, the insulating insert covers the entire surface of the bushing. In this case, the insulating insert completely covers the surface of the bushing in both the axial and circumferential directions.
[0039] According to 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.
[0040] 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.
[0041] 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.
[0042] 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. Attached Figure Description
[0043] 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:
[0044] Figure 1 This is a half-view of the axial section of a bearing device according to an exemplary embodiment of the present invention.
[0045] Figure 2 It comes from Figure 1 A partial exploded perspective view of the bearing assembly, wherein the insulating insert of the assembly is not shown, and
[0046] Figure 3 This is a half-view of the axial section of a bearing device according to another exemplary embodiment of the present invention. Detailed Implementation
[0047] Figure 1 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.
[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 of 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 radially opposite side of the outer surface 14a, and two radially opposite faces 14c, 14d that define the hole axially. The outer surface 14a and the hole 14b define the radial thickness of the outer ring 14.
[0054] 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.
[0055] The outer ring 14 also includes an outer raceway 20 formed on the bore 14b for the rolling element 16. The raceway 20 points inward in the radial direction.
[0056] In the exemplary embodiment shown, a first groove 22 is formed in the front face 14c of the outer ring. The groove 22 is oriented axially outward of the outer ring. The groove 22 has a bottom that is offset axially relative to the front face 14c towards the inside of the ring. 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.
[0057] Similarly, a second groove 24 is formed in the front surface 14d of the outer ring. The groove 24 is oriented axially outwards towards the outer side of the outer ring. The groove 24 has a bottom that is offset axially relative to the front surface 14d towards the inner side of the ring. 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.
[0058] 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.
[0059] The insulating sleeve 26 includes a bushing 28 and an insulating insert 30 radially positioned between the outer ring 14 and the bushing 28. The insulating insert 30 is overmolded onto the outer ring 14 and the bushing 28.
[0060] The bushing 28 has an annular shape. The bushing 28 is formed as a single piece. In this case, the bushing 28 is formed from a single piece. Preferably, the bushing 28 is made of steel. The bushing 28 can advantageously 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 sintering and stamping.
[0061] The bushing 32 includes an axial portion 32a and a first annular radial flange 32b and a second annular radial flange 32c, each of which continues the axial portion radially inward. Each flange 32b, 32c extends radially. Each flange 32b, 32c continues the axial end of the axial portion 32a. In the exemplary embodiment shown, the flanges 32b, 32c are annular. Alternatively, at least one of the flanges 32b, 32c may be in the form of sectors spaced apart from each other in the circumferential direction.
[0062] The bushing 28 includes a cylindrical axial outer surface 28a and a cylindrical bore 28b, the bore 28b being radially opposite to the outer surface 28a, and the axis 25 of the bore 28b being coaxial with the axis X-X'. The bore 28b forms the inner surface of the bushing 28. An axial portion 32a of the bushing defines the outer surface 28a and the bore 28b. The outer surface 28a and the bore 28b define the radial thickness of the bushing 28. The outer surface 28a 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.
[0063] Bushing 28 also includes two opposing radial frontal faces 28c and 28d that define the outer surface 28a in the axial direction. Frontal faces 28c and 28d define the axial length of the bushing. Frontal face 28c is defined by flange 32b, and frontal face 28d is defined by flange 32c. More specifically, frontal face 28c is defined by the outer face of flange 32b, and frontal face 28d is defined by the outer face of flange 32c.
[0064] In the exemplary embodiment shown, the front faces 28c and 28d of the bushing are coplanar with the front 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 may be axially set back from or protrude from the faces 14c and 14d of the outer ring.
[0065] The radial dimension of flange 32c of the bushing is larger than that of flange 32b. The flanges 32b and 32c of the bushing are asymmetrical with respect to the radial midplane of the device.
[0066] In the exemplary embodiment shown, the flange 32b is radially recessed relative to the outer surface 14a of the outer ring. In other words, the free end of the flange 32b is radially offset outward relative to the outer surface 14a. The flange 32b is radially recessed from the groove 22 of the outer ring.
[0067] In the exemplary embodiment shown, the bushing flange 32c extends radially beyond the outer surface 14a of the outer ring, i.e., it protrudes radially inward relative to the outer surface 14a. In other words, the free end of the flange 32c is radially offset inward relative to the outer surface 14a of the outer ring. The flange 32c extends partially within a groove 24 in the outer ring. The flanges 32b and 32c are at a distance from the outer ring 14.
[0068] 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).
[0069] 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 in both the axial and circumferential directions. The insulating insert 30 also covers the grooves 22 and 24 in the outer ring.
[0070] 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 in both the axial and circumferential directions. The insulating insert 30 covers the hole in the axial portion 32a of the bushing.
[0071] The insulating insert 30 also covers the internal face of each flange 32b, 32c of the bushing. The internal face of each flange 32b and 32c and the outer face on the opposite side of the internal face define the axial thickness of the flange. For each flange 32b and 32c, the internal face is oriented axially toward the inside of the device, and the outer face is oriented axially toward the outside of the device. The insulating insert 30 also covers the free end of each flange 32b, 32c of the bushing.
[0072] 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 bore 30b radially opposite to the outer surface 30a, and two radially opposite faces 30c, 30d defining the bore and the outer surface axially. The radial faces 30c, 30d define the insulating insert 30 axially. The outer surface 30a and the bore 30b define the radial thickness of the insulating insert 30. The outer surface 30a radially contacts the bore 28b in the bushing. The outer surface 30a also radially contacts the free ends of each flange 32b, 32c of the bushing. The outer surface 30a has a stepped shape. The bore 30b radially contacts the outer surface 14a of the outer ring and the grooves 22, 24. The bore 30b has a stepped shape.
[0073] In the exemplary embodiment shown, the outer ring, insulating insert, and bushing have coplanar surfaces 14c, 30c, 28c and 14d, 30d, 28d.
[0074] Alternatively, other configurations can be provided. For example, the insulating insert 30 can have a smaller axial dimension and be axially recessed from the outer ring faces 14c, 14d. Alternatively, the insulating insert 30 can have a larger axial dimension and be axially protruding 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, 29d.
[0075] 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.
[0076] To manufacture bearing assemblies, the following methods shall be followed.
[0077] In the first step, bearing 10 and bushing 28 are installed inside a mold provided for covering the molded insulating insert 30. In this position inside the mold, bushing 28 is radially positioned at a distance from the outer ring 14 of the bearing. Bearing 10 is previously introduced axially toward the interior of bushing 28 towards the small flange 32b.
[0078] Next, in the subsequent second step, a molded insulating insert 30 is overlaid on both the outer ring 14 and the bushing 28 of the bearing.
[0079] Finally, the bearing assembly, which is in its integral form, is removed from the mold.
[0080] Figure 3 The exemplary embodiment shown (where the same elements have the same reference numerals) differs from the previous example in that the hole in the axial portion 32a of the bushing is provided with two slots 36, 38 that are axially spaced and extend circumferentially around the axis 25 of the hole in the bushing. Each slot 36, 38 is radially oriented toward the outer ring 14, i.e., radially oriented toward the inner side.
[0081] In the exemplary embodiment shown, each slot 36, 38 is annular. Alternatively, at least one of the two slots 36, 38 may not extend through 360°, or may be formed by a series of turns that extend in the circumferential direction and are spaced apart from each other in the circumferential direction.
[0082] Each slot 36, 38 is defined in the axial direction by two facing lateral sides, which have a straight profile in the axial section and are connected together by an axial bottom. Alternatively, other shapes can be provided, such as slots with an arcuate shape oriented inward in this case. In another variation, bushing 28 may also not have slots 36, 38.
[0083] The insulating insert 30 also includes two ribs 40, 42 that extend radially outward from the outer surface 30a and are each received within one of the slots 36, 38 in the bushing. The ribs 40, 42 have shapes complementary to the shapes of the associated slots 36, 38. Each rib 40, 42 protrudes from the outer surface 30a of the insulating insert. Each rib 40, 42 is formed on the outer surface 30a during the overmolding of the insulating insert 30.
[0084] 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 insert 30 is overmolded, is the outer ring.
[0085] Alternatively, a reverse arrangement can be provided, in which the insulating insert 30 is overmolded onto the second ring 14, which is the inner ring. In this case, the insulating sleeve is located in the bore 12a in the inner ring. Thus, the insulating insert is radially positioned between the bore 12a in the inner ring and the outer surface of the bushing. The insulating insert is overmolded on the inner ring and at least overmolded on the outer surface of the bushing. The bore in the bushing defines a bore in the bearing assembly.
[0086] 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 an integral 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 including an outer surface (28a) defining the radial thickness of the bushing and an inner surface (28b) on the opposite side of the outer surface, the insulating insert (30) being overmolded on the second ring (14) of the bearing and at least overmolded on one of the outer and inner surfaces of the bushing (28), characterized in that, The bushing (28) includes an axial portion (32a) and a first flange (32b) and a second flange (32c), the axial portion (32a) defining the surface of the bushing (28) on which the insulating insert (30) is overmolded, the first flange (32b) and the second flange (32c) extending the axial portion radially toward the second ring (14), the insulating insert (30) also being overmolded on the inner surface of each of the first flange (32b) and the second flange (32c), the second flange (32c) having a radial dimension greater than that of the first flange (32b).
2. The apparatus according to claim 1, characterized in that, The second flange (32c) of the bushing extends radially beyond the second ring and covers the outer surface (14a) or inner surface of the insulating insert (30).
3. The apparatus according to claim 2, characterized in that, The first flange (32b) of the bushing retracts radially from the outer surface (14a) or inner surface of the second ring.
4. The apparatus according to claim 3, characterized in that, A first groove (22) is formed in the first front surface of the second ring (14), and a second groove (24) is formed in the second front surface of the second ring (14). The first groove (22) and the second groove (24) define the outer surface (14a) or inner surface of the second ring in the axial direction. The first flange (32b) of the bushing is radially distanced from the first groove (22), and the second flange (32c) extends partially in the second groove (24).
5. The apparatus according to any one of the preceding claims, characterized in that, The insulating insert (30) includes two front faces (30c, 30d) defining the axial length of the insert, and at least one of the first flange (32b) and the second flange (32c) of the bushing is axially flush with one of the front faces (30c, 30d) of the insulating insert.
6. The apparatus according to any one of the preceding claims, characterized in that, The surface of the bushing (28) is provided with at least one slot (36) extending in the circumferential direction, and the attachment rib (40) of the insulating insert having a complementary shape extends within the slot (36).
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 from sheet metal blanks by cutting, pressing and rolling.
9. The apparatus according to any one of the preceding claims, characterized in that, The insulating insert (30) is made of synthetic material or elastomeric material.
10. An electric motor comprising a housing, a shaft, and at least one bearing assembly according to any one of claims 1 to 9, the bearing assembly being radially mounted between the housing and the shaft.