Bearing arrangement comprising an electrically insulating insulation part

Abstract

A bearing arrangement (10) for a rotor of an electric machine, which rotor is rotatable about a rotation axis AD, comprising a hub element (12), a shaft element (16) which is held via a bearing unit (14) so as to be rotatable relative to the hub element (12) about the rotation axis AD, the hub element (12) being designed in multiple parts with a first hub part (18) and a second hub part (20) and an electrically insulating insulation part (22) produced from a potting compound connecting the first and the second hub part (18, 20) to each other, and mutually facing peripheral surfaces (24, 26) of the first and the second hub part (18, 20) forming a mutually substantially complementary surface profile.

Description

[0001] Bearing arrangement with electrically insulating insulating part

[0002] Description

[0003] The invention relates to a bearing arrangement for a rotor of an electric machine rotatable about an axis of rotation AD, comprising a hub element, a shaft element rotatable about the axis of rotation AD via a bearing unit, wherein the hub element is designed in multiple parts with a first hub part and a second hub part, and an electrically insulating insulating part made of a potting compound connects the first and the second hub part.

[0004] In generators and electric motors, the bearing units between the shaft element and the housing-side bearing housing must be electrically insulated in some applications to prevent damage from electrical erosion caused by the current flowing between the rolling elements and the bearing rings. Several methods are known for electrically insulating the bearing units. One option is to apply an insulating ceramic layer directly to the shaft element. Alternatively, a ceramic coating can be applied to the rolling elements or the raceways of the bearing units. Applying ceramic coatings requires prior knowledge and is technically complex. Finally, there are bolted, clamped, or bonded insulating components that are positioned on the housing side of the bearing units and form part of the hub. However, these require complex prefabrication and precise fitting into the dimensional specifications.In this context, EP 1 793 474 A2, JP 2008148453 A and KR 101005616 Bl. should be mentioned. There is a constant need to simplify the electrical insulation of such storage units.

[0005] The object of the invention is to demonstrate measures that simplify the electrical insulation of such bearing units.

[0006] The problem is solved by a bearing arrangement with the features of claim 1. Preferred embodiments are specified in the dependent claims and the following description, each of which, individually or in combination, can represent an aspect of the invention. When a feature is presented in combination with another feature, this serves only to simplify the presentation of the invention and is in no way intended to imply that this feature cannot also be a further development of the invention without the other feature.

[0007] One embodiment relates to a bearing arrangement for a rotor of an electric machine rotatable about an axis of rotation AD, comprising a hub element, a shaft element rotatably held relative to the hub element about the axis of rotation AD by means of a bearing unit, wherein the hub element is designed in multiple parts with a first hub part and a second hub part, and an electrically insulating insulating part made of a potting compound connects the first and the second hub part together, and wherein mutually facing circumferential surfaces of the first and the second hub part form a substantially complementary surface profile such that the first and the second hub part undercut each other when viewed from an axial direction.

[0008] The two surface profiles do not need to be strictly geometrically complementary. It is considered sufficient if the profile of one surface is fundamentally reversed by the profile of the other. The pairing of surfaces is designed such that the embedded insulating component, made of a potting compound, is primarily subjected to compressive stress during operation of the electrical machine. The shape of the insulating component, determined by the complementary surface profile, is capable of absorbing the resulting axial and radial forces.

[0009] The insulating part, made from a potting compound, ensures that no harmful electric current can flow through the bearing unit, thus preventing electrical erosion.

[0010] For the hub element, it can advantageously be provided that the first hub part is arranged radially inside the second hub part. This ensures that a main extension direction of the insulation part runs essentially parallel to the axis of rotation AD.

[0011] In a preferred embodiment of the complementary surface profile of both hub parts, this is designed as a tongue-and-groove arrangement. Depending on the design constraints, the tongue can be arranged on the outer, first hub part and the groove on the inner, second hub part. However, it can also be advantageous to have the arrangement reversed, namely that the groove is on the outside and the tongue on the inside.

[0012] Preferably, the potting compound is a two-component epoxy resin.

[0013] The problem is further solved by a method for manufacturing a bearing arrangement in which a hub element, round with respect to an axis of rotation AD and with an axially extending and circumferential groove, is provided, the groove is filled with an electrically insulating potting compound to form an insulating part, and a radial web axially closing the groove is removed by a material-removing machining process to obtain a multi-part hub element with a first and second hub part connected by the insulating part. In a preferred embodiment, the hub element is provided by a casting process, wherein the hub element is preferably made of gray cast iron.

[0014] The invention is explained below by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination. The drawings show:

[0015] Fig. 1: Exemplary and schematic representation of an electric machine,

[0016] Fig. 2: an embodiment of the bearing arrangement according to the invention for an electric machine according to Fig. 1 and Fig. 1.

[0017] Fig. 3: a process for manufacturing a bearing arrangement for an electric machine according to Fig. 1.

[0018] Figure 1 shows, purely by way of example, an electric machine, for instance in the form of a generator 100, with a housing 102, a stator 104 and a shaft element 106 designed as a rotor shaft with a rotor 108. The rotor 108 is rotatably mounted in the housing 102 about an axis of rotation AD via a bearing arrangement 10.

[0019] The bearing arrangement 10 has a hub element 12 in which a bearing unit 14, comprising, for example, two rolling bearings, is accommodated. The bearing unit 14 is provided on both axial sides by a bearing cap 34, which ensures a corresponding seal against the shaft element 106 and the hub element 12. The hub element 12 is connected to the housing 102 via a bearing shield 36.

[0020] Figure 2 shows an embodiment of the bearing arrangement 10 according to the invention. Here, the hub element 12 is multi-part, comprising a radially inner first hub part 18 and a radially outer second hub part 20. An electrically insulating insulating element 22, made of a potting compound, is held between the first and second hub parts 18, 20. The insulating element 22 connects the first and second hub parts 18, 20 to each other. The potting compound is preferably a two-component epoxy resin. In particular, axial and radial compressive forces can be transmitted between the first and second hub parts 18, 20 via the insulating element 22. For this purpose, the mutually facing circumferential surfaces 24, 26 of the first and second hub parts 18, 20 form a substantially complementary surface profile. The complementary surface profile can be configured as a tongue-and-groove arrangement 28, as shown here.Furthermore, the complementary surface profile can be designed such that the first and second hub parts 18, 20 undercut each other when viewed from an axial direction.

[0021] Figures 3a) to 3d) describe a process for manufacturing a bearing assembly 10 with a multi-part hub element 12, in which an electrically insulating insulating part 22, made of a potting compound, connects the first and second hub parts 18, 20. A hub element 12, round with respect to an axis of rotation AD and with an axially extending and circumferential groove 30, is provided (Figure 3a). The hub element 12 is initially a single piece, with the later first and second hub parts connected by a radial web 32. The radial web 32 also closes the groove 30 on one axial side. The groove 30 is then filled with an electrically insulating potting compound to form an insulating part 22 (Figure 3b).The radial web 32 is removed via a material removal process, resulting in a multi-part hub element 12 with a first and second hub part 18, 20 connected by the insulating part 22 (Figures 3c and 3d). Removing the radial web 32 eliminates the electrical bridge, thus electrically isolating the two hub parts 18, 20 from each other. The hub element 12 is then machined to its installation dimensions, and the bearing assembly 10 is assembled with the bearing unit 14. Reference numeral list.

[0022] 10 Storage arrangement

[0023] 12 hub element

[0024] 14 storage units

[0025] 16 wave elements

[0026] 18 Hub part

[0027] 20 Hub part

[0028] 22 Insulation part

[0029] 24 Circumferential area

[0030] 26 Circumferential area

[0031] 28 tongue-and-groove arrangement

[0032] 30 Nut

[0033] 32 Radial Bridge

[0034] 34 bearing caps

[0035] 36 Storage sign

[0036] 100 Generator

[0037] 102 cases

[0038] 104 Stator

[0039] 106 wave element

[0040] 108 rotor blades

Claims

Patent claims 1. Bearing arrangement (10) for a rotor of an electric machine rotatable about an axis of rotation (AD), comprising a hub element (12), a shaft element (16) rotatably held relative to the hub element (12) about the axis of rotation (AD) via a bearing unit (14), wherein the hub element (12) is made in multiple parts with a first hub part (18) and a second hub part (20), and an electrically insulating insulating part (22) made of a potting compound connects the first and the second hub part (18, 20) together, and wherein mutually facing circumferential surfaces (24, 26) of the first and the second hub part (18, 20) form a substantially complementary surface profile such that the first and the second hub part (18, 20) undercut each other when viewed from an axial direction.

2. Bearing arrangement (10) according to claim 1, characterized in that the first hub part (18) is arranged radially inside the second hub part (20).

3. Bearing arrangement (10) according to claim 1 or 2, characterized in that the complementary surface profile is designed as a tongue-and-groove arrangement (28).

4. Bearing arrangement (10) according to one of claims 1 to 3, wherein the potting compound is a two-component epoxy resin.

5. Method for manufacturing a bearing arrangement (10) in which a hub element (12) round with respect to an axis of rotation AD and with a groove (30) extending in the axial direction and running circumferentially is provided, the groove (30) is filled with an electrically insulating potting compound to form an insulating part (22) and a radial web (32) axially closing the groove (30) is removed by a material removal process to obtain a multi-part hub element (12) with a first and second hub part (18, 20) connected by the insulating part (22).

6. Method according to claim 5, characterized in that the hub element (12) is provided by a casting process.

7. Method according to claim 5 or 6, characterized in that the hub element (12) is manufactured from gray cast iron using the casting process.

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