Method for producing a coil device for an electric machine, coil device for an electric machine, and electric machine

Abstract

The invention relates to a method for producing a coil device (1), in particular a multi-layer coil device for an electric machine (10), wherein a) at least one electrically non-conductive fastening element (2) combined with an adhesive in the form of a wrappable tape is placed in and / or on a coil body (3) having Litz wires (5), b) at least one electrical insulating means (4) is placed on the outside of the coil body (3), in particular also on the fastening element (2), and c) the entirety of fastening element (2), coil body (3) and electrical insulating means (4) is integrally joined together as a result of pressure action (P) and / or thermal action (T), by adhesive bonding or melting of the adhesive, so as to form the coil device (1). The invention also relates to a coil device (1) produced by means of said method and to an electric machine (10) having corresponding coil devices (1).

Description

[0001] Method for producing a coil device for an electrical machine, coil device for an electrical machine and electrical machine

[0002] Description

[0003] This disclosure relates to a method for producing a coil device for an electrical machine having the features of claim 1, a coil device for an electrical machine having the features of claim 10 and an electrical machine having the features of claim 11.

[0004] Electric machines are used, for example, for drives in the transport sector, with particular emphasis on applications in automobiles and / or aircraft.

[0005] For aerospace applications, these electric machines must generally meet particularly stringent requirements in terms of energy efficiency and weight. A compact design is also crucial.

[0006] For example, in order for an electric drive to generate the required mechanical torque, winding arrangements of insulated coil devices are arranged around a stator and subjected to a voltage. In modern electric drives, the electrical machines are driven by inverters with high-frequency voltage (HF voltage). For HF voltages, so-called high-frequency stranded wires, also known as HF stranded wires, are preferred as the coil material. These consist of a large number of interwoven wires, usually insulated from one another by varnish. This minimizes power losses due to the skin effect and the proximity effect, which would occur with solid wires.

[0007] In electric drives, the coil devices are typically arranged in slots around the circumference of the stator to generate an electromagnetic force. In such a configuration, the coil devices must be provided with slot paper, i.e., insulation, to ensure electrical insulation of the coil material and prevent mechanical damage when inserting the coil material into the slots. Such coil devices are also referred to as multi-layer coil devices.

[0008] In principle, such coil devices are known, for example, from US 2008 / 0122310 A1, JP 2016201930 A, DE 10 2004 005 033 A1, US 2017 / 0 033 634 A1 and JP H08-182269 A.

[0009] However, the object is to provide, in particular, an efficient method for producing such coil devices.

[0010] To produce a coil device, in particular a multi-layer coil device for an electrical machine, at least one fixing element combined with an adhesive is first arranged in and / or on a coil former with high-frequency strands. The at least one fixing element is electrically non-conductive and in the form of a windable strip. The adhesive in and / or on the strip of the fixing element can then be melted, or melted and cured, in a subsequent process step. The adhesive can thus be applied to the coil former in a defined manner, either over a larger area or just in a partial area of ​​the coil former. The bundle of high-frequency strands can be held together in particular by the at least one fixing element. Subsequently - if necessary.With the interposition of at least one further manufacturing step, at least one electrical insulating means is arranged on the outside of the at least one coil body. Depending on the nature and shape of the fixing element, the electrical insulating means can also be arranged on the fixing element, at least partially. The insulating means can thus cover the wound, band-shaped fixing means from the outside. The covering of the at least one fixing means can, in particular, be complete.

[0011] Finally, the entire assembly of the at least one fixing element, the coil former, and the electrical insulation means is bonded together to form the coil device by applying pressure and / or temperature by gluing or melting the adhesive. The coil former is thus bonded in-situ to the fixing element and the electrical insulation means to form the coil device. The fixing element enables the individual windings (high-frequency strands) and the insulation means (e.g., grooved paper) to be fixed to one another to create a compact coil former. However, the pressed coil former is quite porous, so it can later be impregnated with, for example, impregnating resin or varnish.

[0012] This eliminates the need for a separate electrical insulation material, such as insertable grooved paper, when the coil former is integrated into the electrical machine. This eliminates a work step and improves reliability.

[0013] In one embodiment, the at least one fixing means can be arranged on a partial region of the coil former before the insulating means, in particular a grooved paper, is applied to the coil former with the fixing means. Partial application, e.g., at two locations on the coil former arranged parallel to one another, can already be sufficient to achieve sufficiently stable fixing. In particular, the at least one fixing means can be designed as a curable, windable tape. In one embodiment, before the at least one fixing means is applied, the coil former is wound from high-frequency strands, wherein the high-frequency strands are surrounded by a curable coating, in particular a varnish and / or a fabric or foil material. The use of high-frequency strands is particularly efficient in HF applications.

[0014] The wound coil body can be pressed by applying pressure, especially under the influence of temperature, so that the coating hardens.

[0015] In one embodiment, the electrical insulation means can be designed as a slot insulation for corresponding slots of a stator. An electrical insulation means can comprise film-based insulating materials with or made of mica, Kapton (e.g., film materials based on Kapton), aramids, in particular m-aramids, or composite materials with polyimides, insulating materials, in particular polyesters, polyurethanes, PEEK, and / or laminates of Nomex and Kapton.

[0016] In one embodiment, after the material connection of the fixing element, coil body and electrical insulating means to form the coil device, the latter is inserted into a slot of a stator, in particular a stator laminated core of the electrical machine.

[0017] It is also possible that before or after the application of the fixing agent the coil body is provided with a baking varnish and / or the individual high-frequency strands are surrounded with baking varnish.

[0018] The object is also addressed by a coil device produced by a method according to at least one of claims 1 to 9.

[0019] An electric machine, in particular an electric drive in an aircraft with the features of claim 8, also addresses this problem. A plurality of coil devices are arranged in the slots of a stator. Typically, this can be between 30 and 70, in particular between 45 and 55 coil devices. The electric machine can be designed, for example, as an electric motor or as a generator. The electric machine can be used in both fully electric and hybrid drives.

[0020] Embodiments of the invention are described by way of example in the figures.

[0021] Fig. 1 is a schematic representation of a coil device as part of an electrical machine;

[0022] Fig. 1A is a schematic representation of a coil body and a coil device of the embodiment according to Fig. 1 in a plan view with a fixing means and an electrical insulating means;

[0023] Fig. 2 is a schematic sectional view through a stator of an electrical machine with a coil device;

[0024] Fig. 3 is a schematic detailed view of a coil body surrounded by a fixing means and an insulating means;

[0025] Fig. 4 is a schematic side view of the embodiment of a coil body, which is partially held together by a band-shaped fixing means.

[0026] Fig. 5 shows the embodiment of the coil body according to Fig. 4, wrapped on the outer sides with grooved paper;

[0027] Fig. 6 further embodiments of coil bodies, each partially wrapped with band-shaped fixing means;

[0028] Fig. 7 shows the embodiments of the coil bodies according to Fig. 6, wrapped on the outside with grooved paper. Fig. 1 schematically shows an embodiment of a coil device 1 in assembly, although this is only a part of an electrical machine 10, which is not shown in Fig. 1 for reasons of clarity. Fig. 2 schematically shows an arrangement of several such coil devices 1 in connection with an electrical machine 10.

[0029] Fig. 1 shows a coil former 3 which has a large number of high-frequency strands 5 (not shown here). The coil former 3 is elongated in the axial direction A, wherein the coil former 3 has two legs, each of which is arranged in essentially rectangular grooves 7. The coil legs thus have a rectangular cross-section. In the embodiment shown here, the axial extent of the coil former 3 is approximately four times the radial extent, although other embodiments may have different size ratios. In principle, it is possible to adapt the structure of the coil device 1 to the available installation space, so that the illustration in Fig. 1 is only to be understood as an example.

[0030] The illustration in Fig. 1 also shows that the coil body 3 has a fixing means 2 with an adhesive. The fixing means 2 is designed here as a type of adhesive tape that is wound around individual coil windings. The fixing means 2 comprises or consists of an electrically non-conductive material that is provided with an adhesive.

[0031] Figure 3 shows a detail of the coil former 3, which is surrounded by the fixing means 2 (not shown here). The coil former 3 can then be wound around a core during assembly, for example.

[0032] Together, the coil former 3 and the fixing means 2 can also be referred to as a prepreg, since the fixing means 2 represents a pre-impregnation. As will become even clearer in connection with the production of the coil device 1, this prepreg is cured, for example, using an elevated temperature T and / or applying pressure p. An electrical insulating means 4 is arranged on the outside of the composite of the coil former 3 and the fixing means 2, i.e. the electrical insulating means 4 lies laterally on the outside, completely or partially, on the fixing means 2. The electrical insulating means 4 (for example in the form of an electrically insulating paper (groove paper)) here represents electrical insulation of the coil former 3 from the material of the groove 7. Fig. 3 shows how the electrical insulating means 4 is wound and folded around the coil former 3 (see arrows). The electrical insulating material 4 surrounds the coil former 2 here on the inside and outside.

[0033] If the fixing means 2 are covered by the insulating means 4, the liquefied adhesive from the fixing means 2 cannot come into direct contact, or only to a limited extent, with the pressing tool (not shown here) during the pressing process using heat. Therefore, separate protection of the pressing tool, e.g., with a Teflon film, is unnecessary. Furthermore, the use of non-stick films can be disadvantageous, as they can lead to deformation or wrinkling during pressing. This impairs the dimensional accuracy of the coil device 1.

[0034] Fig. 1A shows the entire coil body 3 with the fixing means 2 and the electrical insulating means 4, i.e., without the groove. The fixing means 2 are wound externally around the coil device 1 at two axially spaced locations.

[0035] This entire assembly of coil former 3, fixing means 2, and electrical insulation is subjected to mechanical pressure p and / or an elevated temperature T, so that the adhesive of the fixing element 2 bonds the parts together. The result is a compact coil device 1 including the electrical insulation. This compact coil device 1 can, for example, also be tested in assembly before being installed in the stator 6. This is shown as an example for three coil devices 1 and six slot pairs in Fig. 2.

[0036] The coil device 1 can then be inserted into a stator slot (see Fig. 2) of a rotating electrical machine 10. In this case, tight manufacturing tolerances usually apply. Due to the compact design, which already includes the electrical slot insulation, the risk of damage due to the necessary, sometimes high assembly forces is minimized. This prevents, for example, damage to the slot paper due to radial insertion of the coil device 1 or damage to the coil device 1 or the winding insulation due to radial insertion of the coil. This also prevents the formation of folds, warping of the slot insulation, axial displacement of the slot paper when aligning the coil body 3, and undefined alignment of the slot paper in the area of ​​the slot base, particularly at its edges.

[0037] The basic manufacturing steps described above are described below in conjunction with further optional manufacturing steps. Reference is made to Figs. 1, 1A, and 2.

[0038] Fig. 1 shows a perspective view of a coil former 3 inserted into slots 7. In this schematic view, the slots 7 are laterally delimited by parts that are then arranged in the stator 6 when assembled into the electrical machine (see Fig. 2).

[0039] In Fig. 1A, the object of Fig. 1 is shown in a plan view without the groove-forming parts to describe the manufacture of a coil device 1. The axial extent is designated by A. The viewing direction is directed in the radially inward direction.

[0040] 1. The starting point can be, for example, the winding of a multi-layer coil device 1 using high-frequency stranded wires 5, the individual wires of which are also provided, for example, with a curable coating (baking varnish).

[0041] The winding insulation can be formed by a porous but mechanically stable coating. The curable coating is an embodiment of the previously described fixing element 2. Thus, at the end of this manufacturing step, a coil former 3 with a fixing element 2 is obtained.

[0042] In Fig. 1A, the high-frequency strands 5 are shown only schematically. 2. The wound multilayer coil can then be pressed and the bonding varnish can be cured to increase the copper content in the windings.

[0043] 3. For stabilization, a fixing tape can then be applied (if necessary on the outside of the coil body 3). The fixing tape can also have an adhesive and thus be part of the fixing element 2. In addition, the fixing means 2 can also be a coating. The high-frequency strands 5 are thus completely or partially wrapped with a fixing means 2 with an electrically non-conductive tape.

[0044] 4. The slot insulation (e.g., with slotted paper) is then applied around the coil legs of the coil body 3. The slot insulation forms the electrical insulating material 4, which is also referred to as the main insulation.

[0045] 5. This is followed by pressing p (if necessary at elevated temperature T) and curing of the multi-layer coil device 1 , which thus contains all the necessary insulating materials.

[0046] 6. Application of the compressed multilayer coil device 1, including the slot insulation, into a slot 7 of the stator 6, in particular a stator core, and final impregnation of the entire structure. The use (integration) of the insulating material 4 in the form of slot paper eliminates the need to apply separate insulation during installation. Furthermore, a ready-to-install component is obtained that requires no or essentially no reworking. This ready-to-install component can then be tested as a whole.

[0047] In the following, process steps 4 and 5 are described in detail, with particular reference to Fig. 1 A.

[0048] After the third manufacturing step, the coil former 3 is in a highly compressed state, which is accordingly fixed by the application and subsequent curing of the fixing tape. Before the applied fixing agent 2 (fixing tape) cures, the slot insulation material is applied as electrical insulation 4 in the fourth process step. This can be, for example, film-based insulating materials such as Kapton and / or aramids (e.g. Nomex, an m-aramid or Kevlar, a p-aramid) or composite materials with a polyimide, such as Kapton (e.g. Nomex / Kapton / Nomex) or other insulating materials, such as mica-containing films, polyesters, polyimides, polyurethanes and / or PEEK. The electrical insulation 4 can, for example, be applied in a folded manner all around the linear portion (see Fig. 1A) of the coil device 1. In Fig. 1A, the insulating material 4 is shown as a black layer on the inner and outer sides of the coil legs.

[0049] When bonding the electrical insulation material 4 (grooved paper) to the surface of the coil former 3, thermally conductive and / or thermally conductive filled polymers can also be used, which has a positive effect on the thermal behavior of the overall system. Thermally conductive materials are achieved in particular by adding mineral fillers such as Al2O3, SiO2, and / or BN.

[0050] During the subsequent pressing process p in process step 5 at elevated temperature T, the polymer material in the fixing agent 2 melts between the outer surface of the coil body 3 (Cu surface or winding insulation) and the electrical insulating agent 4 (grooved paper). The pressing process is represented in Fig. 1 by the pressure p and the temperature effect T. In alternative embodiments, the coil device 1 can also be manufactured solely by mechanical pressure or solely by thermal treatment.

[0051] After cooling or hardening of the fixing tape, the coil body 3 is firmly connected to the electrical insulating means 4 (slot insulation material) and forms a coil device 1 which contains all insulating materials and already has an exact target geometry.

[0052] The sectional view of Fig. 2 shows a stator 6 of an electrical machine 10, with three coil devices 1, each with two coil bodies 3, arranged in a pair of slots 7 on the circumference. The sectional plane of Fig. 2 is perpendicular to the rotational axis of the electrical machine 10. For simplicity, only the coil device 2 is shown. Depending on the size and function of the electrical machine, a very large number, e.g., between 45 and 55 coil devices 1, can be provided.

[0053] By fixing the coil assembly 1 in the assembly, a meltable prepreg is used without the need for anti-adhesive layers; the adhesive is enclosed within the coil assembly. This could lead to warping and wrinkles during a pressing process, which could negatively affect the dimensions of the resulting coil assembly.

[0054] Thanks to the integrated manufacturing of the coil device 1, no additional slot paper needs to be inserted when inserting it into the stator 6 of the electric machine 10. Because the installation tolerances are kept as small as possible, the forces required for installation to press the coil device 1 radially into the slot 7 cannot cause damage to the slot paper. This process also prevents the slot paper from being folded or creased, ensuring a well-defined shape, particularly in the area of ​​the slot base or at the corners.

[0055] The resulting coil device 1 can incorporate all the necessary insulating materials and the final target geometry. Accordingly, the required installation tolerances can be kept small. This has the advantage that the proportion of conductor material can be increased, which has a positive effect on the overall performance of the electrical machine 10, as well as the resulting improved current and heat dissipation capacity.

[0056] Because the coil device 1 already contains the complete insulation system, this can be tested as part of a product test before installation in the stator 7, thus improving the reliability and service life of the overall system.

[0057] Furthermore, the application of the slot insulation allows a choice of different materials, such as wrapable tapes or foils.

[0058] 1 Coil device 2 Fixing element

[0059] 3 coil bodies

[0060] 4 Insulating agents

[0061] 5 high-frequency strands

[0062] 6 Stator 7 Groove

[0063] 10 electric machine

[0064] A axial direction p pressure effect

[0065] R radial direction

[0066] T Temperature effect

Claims

Claims 1. Method for producing a coil device (1), in particular a multi-layer coil device for an electrical machine (10), wherein a) at least one electrically non-conductive fixing element (2), combined with an adhesive in the form of a windable tape, is arranged in and / or on a coil body (3) with high-frequency strands (5), b) at least one electrical insulating means (4) is arranged externally on the coil body (3), in particular also on the fixing element (2), and c) the entirety of the at least one fixing element (2), the coil body (3) and the electrical insulating means (4) are connected to one another in a materially bonded manner to form the coil device (1) by applying pressure (p) and / or applying temperature (T) by gluing or melting the adhesive.

2. Method according to claim 1, characterized in that the at least one fixing means (4) is arranged on a partial area of ​​the coil body (3) before the insulating means (4), in particular a grooved paper, is applied to the coil body (3) with the fixing means (4).

3. Method according to claim 1 or 2, characterized in that the at least one fixing means (4) is designed as a hardenable, windable tape.

4. Method according to at least one of the preceding claims, characterized in that before the application of the at least one fixing means (2), the coil body (3) is wound from the high-frequency strands (5), wherein the high-frequency strands (5) are surrounded by a curable coating, in particular a lacquer, and / or a fabric or foil material.

5. Method according to claim 4, characterized in that the wound coil body (3) is pressed by the action of pressure (p), in particular also under the action of temperature (T), and the coating hardens.

6. Method according to at least one of the preceding claims, characterized in that the electrical insulating means (4) is designed as a slot insulation, in particular a slot paper.

7. Method according to at least one of the preceding claims, characterized in that the electrical insulating means (4) comprises film-based insulating materials with or made of Kapton, mica, aramids, in particular m-aramids, or composite materials with polyimides, insulating materials, in particular polyesters, polyurethanes, PEEK and / or laminates made of Nomex and Kapton.

8. Method according to at least one of the preceding claims, characterized in that after the material connection of the fixing element (2), coil body (3) and electrical insulating means (4) to the coil device (1), the latter is inserted into a groove of a stator (6), in particular a stator laminated core of the electrical machine (10).

9. Method according to at least one of the preceding claims, characterized in that before or after the application of the fixing agent (4) the coil body (1) is provided with a baking varnish and / or the individual high-frequency strands (5) are surrounded by baking varnish.

10. Coil device manufactured by a method according to at least one of claims 1 to 9.

11. Electrical machine, in particular an electric drive in an aircraft, characterized by a plurality of coil devices (1) according to claim 7, which are arranged in particular in slots (7) of a stator (6).

12. Electrical machine according to claim 11, characterized in that between 30 and 70, in particular between 45 and 55 coil devices (1) are arranged in the stator (6).

13. Electrical machine according to claim 11 or 12, characterized in that it is designed as an electric motor or generator.

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