Bearing assembly, in particular for an electric motor

Abstract

A bearing assembly includes a bearing having a first bearing ring, a second bearing ring rotatably disposed relative to the first bearing ring, and a plurality of rolling elements in a bearing interior defined by the first bearing ring and the second bearing ring. Also, at least one layer of non-metallic material on the first bearing ring configured to conduct heat away from the first bearing ring and to electrically insulate the first bearing ring and to fill at least one cavity between the first bearing ring and a component to which the first bearing ring is mounted. The at least one layer may be a first layer of a heat-conducting material and a second layer of a different, electrically insulating material.

Claims

1. A bearing assembly comprising: a bearing including a first bearing ring, a second bearing ring rotatably disposed relative to the first bearing ring, and a plurality of rolling elements in a bearing interior defined by the first bearing ring and the second bearing ring, and at least one layer of non-metallic material on the first bearing ring configured to conduct heat away from the first bearing ring and to electrically insulate the first bearing ring and to fill at least one cavity between the first bearing ring and a component to which the first bearing ring is mounted, wherein the at least one layer comprises an electrically insulating first layer and a heat-conducting second layer on the first layer, and wherein the second layer is different than the first layer and comprises a thermal paste or a thermal adhesive.

2. The bearing assembly according to claim 1, wherein the second layer comprises silicone.

3. The bearing assembly according to claim 1, including a metal ring on the first bearing ring, wherein the second layer is provided between the first layer and the metal ring.

4. The bearing assembly according to claim 3, including an additional heat-conducting layer on a side of the metal ring opposite the second layer.

5. The bearing assembly according to claim 3, wherein the second layer are is adhered or overmolded to the metal ring.

6. A bearing assembly comprising: a bearing including a first bearing ring, a second bearing ring rotatably disposed relative to the first bearing ring, and a plurality of rolling elements in a bearing interior defined by the first bearing ring and the second bearing ring, at least one layer of non-metallic material on the first bearing ring configured to conduct heat away from the first bearing ring and to electrically insulate the first bearing ring and to fill at least one cavity between the first bearing ring and a component to which the first bearing ring is mounted, and a metal ring on the first bearing ring, wherein the at least one layer comprises an electrically insulating first layer and a heat-conducting second layer on the first layer, wherein the second layer is provided between the first layer and the metal ring, and wherein the metal ring has a first flange overlying a first axial end of the first bearing ring and a second flange overlying a second axial end of the first bearing ring and wherein at least a portion of the first layer and at least a portion of the second layer are located axially between the first flange and the second flange.

7. The bearing assembly according to claim 6, wherein the metal ring comprises a sheet metal strip having a first end connected to a second end in a materially bonded or interference fit manner at a joint.

8. The bearing assembly according to claim 7, wherein the second layer are is adhered or overmolded to the metal ring.

9. The bearing assembly according to claim 6, wherein the second layer is different than the first layer and comprises a thermal paste or a thermal adhesive.

10. The bearing assembly according to claim 9, including an additional heat-conducting layer on a side of the metal ring opposite the second layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic sectional view through a bearing assembly of an exemplary embodiment of the present disclosure.

(2) FIG. 2 is a schematic sectional view through a bearing assembly of a further exemplary embodiment of the present disclosure.

(3) FIGS. 3A and 3B are schematic views of a strip-shaped carrier blank at different processing stages.

(4) FIG. 4 is a schematic view of a material-bonded connection between ends of a strip-shaped carrier blank of a bearing assembly according to the present disclosure.

(5) FIG. 5 is a schematic view of an interference-fit connection between ends of a strip-shaped carrier blank of a bearing assembly according to the present disclosure.

(6) FIG. 6 is a schematic sectional view through a bearing assembly of a further exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

(7) In the following, identical or functionally equivalent elements are designated by the same reference numbers.

(8) FIGS. 1 and 2 each schematically show a sectional view through a bearing assembly 1 with a rolling bearing 2 as the bearing. The rolling-element bearing 2 comprises an inner ring 4 and an outer ring 6 that form a bearing interior 8 between them in which rolling elements 10 are disposed that roll on raceways 12, 14 that are formed on the inner ring 4 and/or outer ring 6. The bearing itself with its outer ring 6 is received in a housing 15 and supports a shaft 17.

(9) Furthermore, FIGS. 1 and 2 show that an electrical insulator 18 is present on the outer ring 6 on its outer surface 16.

(10) In the exemplary embodiment of the FIG. 1, the electrical insulator 18 comprises an electrical insulation layer 22 on which a heat-conducting layer 23 is applied that is designed to fill the air-filled cavities (not depicted) that are present between the electrical insulation layer 22 and the housing 15 so that an improved heat transmission is achieved between the rolling- element bearing 2 and the housing 15. Micro-air-inclusions and micro-cavities are often present between the bearing ring 6 and the electrical insulating layer 22 or between the electrical insulation layer 22 and the receiving component, here the housing 15, even when a press fit is used and when some portions of these objects are in direct contact. The presence of these micro- air-inclusions and micro-cavities impairs heat conduction in electrically insulated bearings so that a heat accumulation often occurs that can damage the bearing. These cavities can be filled with the heat-conducting layer 23 so that a material contact, and thus an improved heat transport, is always possible.

(11) Here the heat-conducting layer is preferably a heat-conducting paste, in particular based on silicone, that can be applied thinly, and due to its soft material characteristics fits well into the cavities. (The head-conducting layer is not drawn to scale in the Figures.)

(12) Furthermore, in order to provide a particularly good protection against damage to the electrical insulation layer 22 and the heat-conducting layer 23, as shown in the exemplary embodiment of FIG. 2 an annular carrier 20 surrounds the electrical insulation layer 22 and the heat-conducting layer 23 and contacts the housing 15 directly or via a further heat conducting layer 25, illustrated in FIG. 6.

(13) Furthermore, FIGS. 1 and 2 show that the insulation layer 22, the heat-conducting layer 23, and/or the annular carrier 20, has a U shape with two bent edges 24, 26 that extend along end surfaces 28, 30 of the bearing outer ring 6 and axially attach the annular carrier 20 or the electrical insulator 18 to the bearing outer ring 6. FIG. 2 also shows an additional snap ring 29 that provides an additional axial securing.

(14) As can be seen from FIGS. 3A and 3B, the annular carrier 20 can preferably be manufactured from a strip-shaped carrier blank 32, for example, from a sheet metal strip. Here FIG. 3A shows a strip-shaped carrier ring blank 32 with two short edges 34 that function as abutting edges and two long edges 24, 26 which, as shown in figure section 3B, are bent toward inside bearing interior 8 in order to achieve the U shape of the annular carrier 20 depicted in FIG. 2. Here the bendings or flanges, shown in FIG. 2, of the edges 24, 26 can be introduced before or after a round-bending of the strip-shaped carrier blank 32 for providing the annular carrier 20. In FIG. 3, a bending of the edges 24, 26 before the round-bending is depicted.

(15) The strip-shaped carrier blank 32 can be cut from a large-surface plate or cut down to length from a sheet metal strip, and can thus be individually adapted to the size of the bearing outer ring 6. Here the insulation material of the electrical insulation layer 22 and/or the material of the heat-conducting layer 23 can be applied onto the metal sheet before the cutting, or alternatively after the cutting so that individually produced sizes of electrical insulators 18 are easily providable.

(16) If the electrical insulation layer 22 and/or the heat-conducting layer 23 is not already applied onto the strip-shaped carrier blank 32 or onto the metal sheet, an application of the electrical insulation layer 22 and/or of the heat-conducting layer 23 can also be effected after the bending of the edges 24, 26.

(17) If the strip-shaped carrier blank 32 is provided with the electrical insulation layer 22 and/or the heat-conducting layer 23 and has the optional bending of the edge, the strip-shaped carrier blank 32 is round-bent around the bearing outer ring 6, and its abutting edges 34 are connected to each other in a materially bonded (see FIG. 4) or interference-fit (see FIG. 5) manner.

(18) As FIG. 5 shows in particular, an interference-fit connection can be provided in the form of at least one puzzle-piece-type interference-fit connection 36 in which one of the abutting edges 34-1 has a projection 38, while the other abutting edge 34-2 has an insertion area 40 formed complementary to the projection 38, into which insertion area 40 the projection 38 can be snapped. Of course, other interference fits are also possible.

(19) Of course, it is also possible that material bond and interference fit are combined in order to be able to achieve a particularly secure connection of the abutting edges 34 to each other.

(20) Once the bearing ring 6 is surrounded by the electrical insulator 18, and the annular carrier 20 is connected at its abutting edges 34 in a material-bonded and/or interference-fit manner, a fine machining of the annular carrier 20 can be effected in order to achieve a precise required surface for the press fit of the bearing assembly in a housing. This fine machining of the annular carrier 20 also makes it possible that the bearing outer ring 6 itself need not be fine machined. This also reduces the manufacturing costs, since less effort is needed for a fine machining of the annular carrier 20 than for a fine machining of the rolling-element bearing outer ring 6.

(21) Here in particular the surface of the annular carrier 20 that press fits with a receiving component, for example, a housing, is ground to its precise dimensioning, and the raceways 12, 14 of the bearing ring 6 themselves are honed. Of course, further post-processing steps are possible. The finished bearing outer ring 6 with the electrical insulator 18 can then be installed in the electric motor.

(22) By providing at least one heat-conducting layer, the heat transport in electrically insulated bearings can be significantly improved, since air inclusions, which are inevitably present, are reduced or prevented. The electrical insulator 18 can be manufactured from a strip-shaped carrier blank 32 so that the widest range of sizes of bearing outer rings 6 can be easily be equipped with the electrical insulator 18. Individual sizes are thereby also easy to manufacture without different tube-type blanks needing to be provided or manufactured for every size of bearing. The material-bonded or interference-fit connecting also does not represent a disadvantage since the annular carrier is usually still machined prior to an installation. Any protruding welding seams can be easily removed in this step. Overall, the bearing assembly discussed above represents a simple and cost-effective way to electrically insulate a bearing disposed in an electric motor or an electrical machine.

REFERENCE NUMBER LIST

(23) 1 Bearing assembly 2 Rolling-element bearing 4 Inner ring 6 Outer ring 8 Bearing interior 10 Rolling element 12,14 Raceways 15 Housing 16 Outer surface 17 Shaft 18 Electrical insulator 20 Annular carrier 22 Electrical insulation layer 23 Heat-conducting layer 24, 26 Bent edges 25 Further heat conducting layer 28, 30 End surfaces 29 Snap ring 32 Carrier blank 34 Abutting edges 36 Interference-fit connection 38 Projection 40 Insertion area