Insulating device for a bearing

Abstract

Disclosed is an insulating device (30) for a bearing (10) and an insulated bearing. The bearing can be mounted in a seat (2). The bearing has an inner ring (14) and an outer ring (12) and a plurality of rolling elements (16) arranged between the inner ring and the outer ring. The outer ring (12) has an outer peripheral surface (18) and opposite axial ends (20, 22). The insulating device (30) includes: a first annular member (32) adapted to contact the outer peripheral surface (18) of the outer ring (12); and a second annular member (34) also adapted to contact the outer peripheral surface (18) of the outer ring (12). The first member (32) and the second member (34) form the insulating device (30). The insulating device is adapted to contact both the outer ring (12) and the seat (2) in an assembled state where the bearing (10) is located in the seat (2). The first member (32) is thermally conductive and electrically insulating, and the second member (34) is electrically insulating.

Description

Technical Field

[0001] The present invention relates to an insulating device for a bearing that can be installed in a seat (bearing housing / case) (housing), and the insulating device is used to electrically insulate the bearing from the seat. Background Art

[0002] Bearing assemblies are well known and typically include an inner ring and an outer ring, with a plurality of rolling elements disposed between the inner ring and the outer ring. In the case where a bearing assembly operates (operates) in an electrical environment (such as, a motor (electric motor)), when current passes through the bearing, the bearing assembly may be damaged. To prevent the flow of such current, it is known to provide an insulating coating or an insulating housing (encasing) for the bearing rings. Unfortunately, even though the insulating materials used to cover the outer ring of a metal bearing are cost effective, they are also thermally insulating (heat insulating), which causes the operating temperature of the bearing assembly to increase, thereby shortening the service life.

[0003] As another alternative, it is also known to use so-called hybrid bearings, in which the rolling elements are made of ceramic to provide electrical insulation, and the rings are made of metal to provide heat transfer. However, hybrid rolling bearings are very expensive.

[0004] Therefore, an object of the present invention is to provide a cost-effective insulating device for a bearing, which also enables (allows) good heat transfer from the bearing to the outside. Summary of the Invention

[0005] This object is solved by the insulating device according to Patent Technical Solution 1 and the insulated bearing assembly according to Patent Technical Solution 11.

[0006] Hereinafter, an insulating device for a bearing assembly is proposed, wherein the bearing assembly can be installed in a seat (bearing housing / case) (housing). The bearing assembly generally has an inner ring and an outer ring, the outer ring having an outer peripheral surface and opposite axial ends, and a plurality of rolling elements are provided between the inner ring and the outer ring. The insulating device further includes: a first annular member adapted (configured) to contact the outer peripheral surface of the outer ring; and a second annular member also adapted to contact the outer peripheral surface of the outer ring. The first member and the second member form the insulating device and are adapted (configured) to contact both the outer ring and the seat in the assembled state where the bearing is in the seat.

[0007] In order to electrically insulate the bearing from the housing without increasing the operating temperature inside the bearing, the first component is thermally conductive but electrically insulating, while the second component is only electrically insulating. The thermally conductive but electrically insulating material is, for example, a ceramic such as alumina. As an alternative, the electrically insulating material is a metal with an insulating coating, for example, anodized aluminum.

[0008] Due to the thermally conductive material of the first component, the heat accumulated during the operation of the bearing can be transferred from the bearing to the housing. In principle, a thermally conductive and electrically insulating material can also be used for both the first and second components of the insulating device. However, such materials are very expensive and difficult to attach to the outer ring. Therefore, the second component is made of a less costly but still electrically insulating material.

[0009] Preferably, the second component is made of a heat-insulating and very cost-effective plastic material. Another advantage of the plastic material is that it can be shaped into different forms, for example, by injection molding. In addition, the ring can be overmolded with the plastic material. This enables novel attachment possibilities for the insulating device, which will be further explained below.

[0010] According to another preferred embodiment, the first component and the second component abut against each other and / or overlap. Thereby, a continuous insulating device covering the entire outer peripheral surface of the outer ring can be provided. This ensures continuous electrical insulation between the bearing and the housing.

[0011] According to another preferred embodiment, the first component and / or the second component includes: an axially extending portion having a cylindrical inner surface adapted to at least partially contact and / or cover the outer peripheral surface of the outer ring; and a radially extending flange portion adapted to at least partially contact and / or cover the axial end of the outer ring. This design enables the insulating device to be tightly fitted onto the outer ring of the bearing, such that the outer ring is electrically insulated on all sides. In addition, the radially extending flange portion can be used to fasten the insulating device to the outer ring.

[0012] Further advantageously, the axially extending portion of the first component has an axial length greater than the axial length of the axially extending portion of the second component. Thereby, an effective large thermal contact surface can be provided, which in turn enables sufficient thermal conductivity such that heat does not accumulate in the bearing but is transferred to the housing.

[0013] In another preferred embodiment, the first component has a first fastening structure and the second component has a second fastening structure complementary to the first fastening structure, wherein the first and second fastening structures are designed to fasten the first and second components in a form fit manner. This form fit engagement is feasible because the material of the second component is chosen to be less hard than the material of the first component (i.e., ceramic). Thus, even if one component is made of ceramic which is usually too hard to be used for form fit engagement, the first and second components can be attached to each other in a form fit manner. The provision of complementary fastening structures for the first and second components that provide a form fit allows the insulating device to be easily and quickly assembled to the bearing assembly. Thus, it is particularly preferred that the fastening structure of the first component and the fastening structure of the second component are complementary designed recesses and protrusions that engage with each other, for example, the recess and the protrusion snap into each other.

[0014] According to another preferred embodiment, the first component and / or the second component further comprises at least one retaining element adapted to retain the first component and / or the second component to the outer ring. In addition to fastening the first and second components to each other, it is also necessary to provide the possibility of retaining the insulating device to the bearing itself. Since the outer ring must be fixed to the seat in a non-rotatable manner, any intermittently configured component (such as the insulating device) also needs to be fixed to the outer ring and the seat in a non-rotatable manner so that no relative movement occurs between the insulating device and the outer ring and between the insulating device and the seat.

[0015] To attach the insulating device to the outer ring, the insulating device preferably further comprises at least one retaining element that projects radially inwards and is preferably arranged at an axially extending portion. The projecting element is also adapted to engage with a recess provided at the outer peripheral surface of the outer ring.

[0016] As described above, the insulating device is preferably attached to the outer ring in a simple but secure manner. In a preferred embodiment, wherein the second component is made of a slightly elastic / deformable material (i.e., a material less hard than the ceramic material of the first component) (e.g., plastic), the outer ring and the insulating device are preferably assembled as follows: the first component of the insulating device is arranged at the outer ring, then the second component is placed at the outer ring and snapped into the fastening structure at the first component while snapping into a groove or retaining structure at the outer ring. Thus, an insulated bearing assembly can be provided which can then be assembled to the seat / shaft.

[0017] Another aspect of the present invention relates to an insulated bearing assembly, which includes a bearing that can be installed in a seat and has an inner ring, an outer ring, and a plurality of rolling elements arranged between the inner ring and the outer ring. In addition, the outer ring has an outer peripheral surface and opposite axial ends. At the outer peripheral surface of the outer ring, an insulating device as described above is configured and attached. Thus, an insulated bearing assembly can be provided that allows the insulating device to be easily attached to the bearing and the bearing to be non-rotatably installed in the seat.

[0018] Other preferred embodiments are defined in the dependent claims, as well as in the description and the drawings. Thus, elements described or shown in combination with other elements may exist alone or in combination with other elements without departing from the scope of protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, preferred embodiments of the present invention are described with reference to the drawings, wherein the drawings are merely exemplary and are not intended to limit the scope of protection. The scope of protection is defined only by the appended claims.

[0020] The drawings show:

[0021] Figure 1 : An axial sectional view of a bearing arrangement, the bearing arrangement including an insulated bearing according to an embodiment of the present invention installed between a shaft and a seat; and

[0022] Figure 2 : Figure 1 An enlarged view of the upper part of the insulated bearing.

[0023] LIST OF REFERENCE NUMERALS

[0024] 100 Bearing assembly

[0025] 2 Seat

[0026] 4 Shaft

[0027] 6 Inner peripheral surface of the seat

[0028] 10 Bearing

[0029] 12 Outer ring

[0030] 14 Inner ring

[0031] 16 Rolling element

[0032] 18 Outer peripheral surface

[0033] 20, 22 Axial ends

[0034] 24, 26 Radially extending surfaces

[0035] 30 Insulating device

[0036] 32 The first component

[0037] 34 The second component

[0038] 36, 38 Fastening structures

[0039] 40 Groove

[0040] 42 Nose

[0041] 44 Inner circumferential surface

[0042] 46 Groove

[0043] 48 Nose

[0044] 50, 52 Flange portions

[0045] 54 Recess

[0046] 56 Nose

[0047] 60 Outer circumferential surface

[0048] L Length of the first component

[0049] LB Length of the bearing Detailed implementation mode

[0050] In the following, the same or similar functional elements are denoted by the same reference numerals.

[0051] Figure 1 A bearing arrangement 100 is shown. The bearing arrangement 100 includes a bearing 10 which is mounted in a housing 2 and mounted around a shaft 4 to rotatably support the shaft 4 in the housing 2. The housing 2, the shaft 4 and the bearing 10 are rotatable about a central axis of rotation AC. The bearing has an outer ring 12 and an inner ring 14 and a plurality of rolling elements 16 (in the case shown, balls) disposed between the rings 12 and 14. The outer ring 12 also has an outer circumferential surface 18 and opposite axial ends 20, 22, and the axial ends 20, 22 respectively have surfaces 24, 26 extending radially.

[0052] As Figure 1 further shown in Figure 2As shown in more detail, the insulation device 30 is disposed between the outer ring 12 and the seat 2. The insulation device 30 prevents current from flowing from the shaft 4 through the bearing 10 to the seat 2. For this purpose, the insulation device 30 is made of an electrically insulating material. It can further be seen that the insulation device 30 encases the outer ring 12 and extends along the outer peripheral surface 18 as well as along the radial surfaces 24, 26.

[0053] The problem with such an insulation encasement is that the heat generated during the operation of the bearing or the machinery including the bearing cannot be transferred from the shaft 4 to the seat 2, but accumulates in the bearing 10. This in turn reduces the service life of the bearing 10 as well as the service life of the machinery including the bearing 10.

[0054] In order to provide both firm electrical insulation and good thermal conductivity, it has been proposed to provide an insulation device 30 having two components 32 and 34. The first component 32 extends along the outer peripheral surface 18 of the outer ring and is made of a thermally conductive and electrically insulating material (e.g., ceramic). The second component 34 also extends along the outer peripheral surface 18 and is made only of an electrically insulating material (e.g., plastic).

[0055] In principle, the entire insulation device 30 could also be made of a thermally conductive and electrically insulating material. However, this is very expensive and, in the case of using ceramics, requires a sophisticated manufacturing process. Since ceramics are very hard, the dimensions of the insulation device made only of ceramics need to be precisely set to fit the dimensions of the outer ring. In addition, the insulation device must be firmly attached to the outer ring so that the outer ring can be non-rotatably attached to the seat. This in turn requires the insulation device to also be non-rotatably attached to the outer ring and / or the seat. In the case where the insulation device is made of ceramics, such an attachment cannot be guaranteed.

[0056] Therefore, the second component 34 is made of a second material (e.g., a plastic material) that is electrically insulating but may not be as hard as ceramics, which in turn allows for easy manufacturing and a firm and non-rotatable attachment of the insulation device to the outer ring. The second material or the plastic can respectively be a resilient material or at least a slightly deformable material such that the second component 34 can be attached to the first component 32 and / or the outer ring 12 without breaking.

[0057] To fix the first part 32 and the second part 34, the first part and the second part include fastening structures 36, 38. In the illustrated embodiment, the fastening structure 36 of the first part 32 is designed as a groove 40 and a nose 42. The groove 40 extends radially outward from the inner circumferential surface 44 of the first part 32 and is axially limited by the nose 42. The inner circumferential surface 44 of the first part 32 contacts the outer circumferential surface 18 of the outer ring 12. The groove 40 and the nose 42 are designed such that the fastening structure 38 of the second part 34 can snap into it. For this purpose, the fastening structure of the second part 34 includes correspondingly and complementarily designed groove 46 and nose 48, wherein the nose 48 of the second part 34 can snap into the groove 40 of the first part 32, and the nose 42 of the first part 32 can snap into the groove 46 of the second part 34. This ensures the axial and radial attachment of the first part 32 and the second part 34 for forming the insulating device 30. To also fasten the first part 32 and the second part 34 in the circumferential direction, the groove 40 of the first part and / or the groove 46 of the second part is not designed as a continuous annular groove, but is provided as discrete recesses for receiving discrete protruding nose elements.

[0058] In addition to fastening the first part 32 and the second part 34 to each other, the insulating device 30 itself must be attached to the outer ring 12, preferably in a non-rotatable manner.

[0059] For this purpose, the first part 32 and the second part 34 each have radially extending flange portions 50, 52, and the flange portions 50, 52 extend along the axial ends 20, 22 of the outer ring 12 respectively. In the assembled state, that is, when the complementary fastening structures 36, 38 are engaged, the radially extending flange portions 50, 52 contact and abut against the radially extending surfaces 24 and 26 of the outer ring 12, thereby preventing any axial movement of the insulating device 30.

[0060] Furthermore, the insulating device 30 may have a holding member for holding the insulating device to the outer ring 12. In Figure 1 and Figure 2 the illustrated embodiment, the outer ring 12 is provided with a recess 54, and the second part 34 includes another nose 56, wherein the nose 56 and the recess 54 engage. This allows a strong coupling between the insulating device 30 and the outer ring 12 and ensures that the insulating device 30 is securely attached to the outer ring 12. To avoid any circumferential movement of the insulating device relative to the outer ring 12, the nose 56 and the recess 54 can be designed as discrete elements.

[0061] Since the insulating device 30 is disposed between the seat 2 and the outer ring 12 and in contact with both the seat 2 and the outer ring 12, radial movement is also prevented.

[0062] It can be further seen from the illustrated embodiment that the first component 32 has an outer peripheral surface 60 that contacts the inner peripheral surface 6 of the seat 2. This contact allows heat transfer between the bearing 10 and the seat 2. To provide good heat transfer, the length L of the first component 32 is maximized, in particular the length L of the outer peripheral surface 60 of the first component 32. As shown, the outer peripheral surface 60 extends over almost the entire length LB of the bearing 10, which provides sufficient thermal contact to provide optimized heat transfer from the bearing 10 to the seat 2.

[0063] Generally speaking, by providing an insulating device having two components made of different materials (where only one material is thermally conductive), an insulating bearing assembly can be provided that achieves good thermal management, good electrical insulation and is cost-effective and easy to manufacture.

Claims

1. An insulating device (30) for a bearing (10) which is mountable in a seat (2), the bearing (10) having an inner ring (14) and an outer ring (12) and a plurality of rolling elements (16) disposed between the inner ring (14) and the outer ring (12), the outer ring (12) having an outer peripheral surface (18) and opposite axial ends (20, 22), wherein, The insulating device (30) comprises: a first component (32) adapted to contact the outer circumferential surface (18) of the outer ring (12); and a second component (34), also adapted to contact the outer circumferential surface (18) of the outer ring (12), wherein the first component (32) and the second component (34) are annular and form the insulating device (30), which is adapted to contact both the outer ring (12) and the seat (2) in the assembled state of the bearing (10) in the seat (2), characterized in that the first component (32) is thermally conductive and electrically insulating, and the second component (34) is electrically insulating, and the first component (32) and / or the second component (34) further comprises at least one retaining element (56) adapted to retain the first component (32) and / or the second component (34) to the outer ring (12).

2. The insulating device (30) according to claim 1, characterized in that, The material of the first component (32) is a ceramic material, or the first component (32) is made of metal with an insulating coating.

3. The insulating device (30) according to claim 1 or 2, characterized in that, Additionally, the material of the second component (34) is thermally insulating, and / or the material of the second component (34) is a plastic material.

4. The insulating device (30) according to claim 1 or 2, characterized in that, The first component (32) and the second component (34) abut against each other, and / or the first component (32) and the second component (34) overlap.

5. The insulating device (30) according to claim 1 or 2, characterized in that, The first component (32) and / or the second component (34) comprises: an axially extending portion, the cylindrical inner surface (44) of which is adapted to at least partially contact and / or cover the outer circumferential surface (18) of the outer ring (12); and a radially extending flange portion (50; 52) adapted to at least partially contact and / or cover the axial ends (20; 22) of the outer ring (12).

6. The insulating device (30) according to claim 5, characterized in that, The axially extending portion of the first component (32) has an axial length (L) greater than the axial length of the axially extending portion of the second component (34).

7. The insulating device (30) according to claim 1 or 2, characterized in that, The first component (32) has a first fastening structure (36; 40; 42), and the second component (34) has a second fastening structure (38; 46; 48) complementary to the first fastening structure (36; 40; 42), wherein the first fastening structure and the second fastening structure are designed to fasten the first component (32) and the second component (34) in a form-fitting manner.

8. The insulating device (30) according to claim 7, characterized in that, The first component (32) and the second component (34) comprise clamping portions (40; 42; 46; 48) for clamping the first component (32) and the second component (34) to each other.

9. The insulating device (30) according to claim 1 or 2, characterized in that, The at least one retaining element (56) is a protruding element configured at the axially extending portion and protruding radially inwards, and is adapted to be received in a recess (54) provided at the outer circumferential surface (18) of the outer ring (12).

10. The insulating device (30) according to claim 2, characterized in that, The ceramic material is alumina.

11. The insulating device (30) according to claim 2, characterized in that, The metal is anodized aluminum.

12. The insulating device (30) according to claim 3, characterized in that, The plastic material is injection molded or overmolded.

13. An insulating bearing (10) assembly, the insulating bearing assembly comprising a bearing (10) capable of being installed in a seat (2), wherein, The bearing (10) has an inner ring (14) and an outer ring (12) and a plurality of rolling elements (16) arranged between the inner ring (14) and the outer ring (12), wherein the outer ring (12) has an outer peripheral surface (18) and opposite axial ends (20, 22), and wherein an insulating device (30) according to any one of the preceding claims is arranged at the outer peripheral surface (18) of the outer ring (12).

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