INSULATED ELECTRIC CONDUCTOR

Abstract

An insulated electric conductor with increased adhesion of an insulating coating includes an electric conductor, preferably made of copper or aluminum, with an insulating coating having either at least one insulating layer made of thermoplastic material, or the insulating layer and a plastic-containing intermediate layer, obtainable by a method in which the electric conductor is placed under a protective gas atmosphere and is bombarded with ions of the protective gas in a gas plasma in order to remove an oxide layer formed on a surface of the electric conductor and/or to increase the surface energy of the electric conductor, and subsequently either the at least one insulating layer or, in the case that the coating includes the plastic-containing intermediate layer, at least the plastic-containing intermediate layer is applied directly to the surface of the electric conductor under a protective gas atmosphere.

Claims

1-53. (canceled)

54. A winding wire for electrical machines, comprising: a flat or round wire made of one or more electrically conductive materials, the flat or round wire having an exterior surface that is free of an oxide layer; and an insulating layer adhering directly to the oxide-layer-free exterior surface to form a coating around the oxide-layer-free exterior surface, the insulating layer being made of at least one thermoplastic material which provides electrical insulation; wherein the at least one thermoplastic material comprises polyetheretherketone [PEEK]; wherein the flat or round wire is designed to conduct an electrical current; wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulating layer being cut circumferentially in a direction perpendicular to an axis of the flat or round wire and the insulated electric conductor being stretched by 20%, is at most 3 mm as measured in a direction of a conductor axis.

55. The winding wire according to claim 54, wherein the insulating layer adheres directly to the oxide-layer-free exterior surface as a result of application under a protective gas atmosphere.

56. The winding wire according to claim 54, wherein the insulating layer has a thickness between 10 m and 1000 m.

57. The winding wire according to claim 54, wherein the insulating layer is an extrusion coated layer on the oxide-layer-free exterior surface.

58. The winding wire according to claim 54, wherein the insulating layer consists of polyetheretherketone [PEEK].

59. The winding wire to claim 54, wherein the one or more electrically conductive materials include copper, aluminum, or a copper alloy.

60. The winding wire according to claim 54, wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulating layer being cut circumferentially in a direction perpendicular to an axis of the flat or round wire and the insulated electric conductor being stretched by 20%, is at most 1 mm as measured in a direction of a conductor axis.

61. A winding wire for electrical machines, comprising: a flat or round wire made of copper, aluminum, or a copper alloy, the flat or round wire having an exterior surface that is free of an oxide layer; and an insulating layer adhering directly to the oxide-layer-free exterior surface to form a coating around the oxide-layer-free exterior surface, the insulating layer being made of at least one thermoplastic material which provides electrical insulation; wherein the at least one thermoplastic material comprises polyaryletherketone [PAEK]; wherein the flat or round wire is designed to conduct an electrical current; wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulating layer being cut circumferentially in a direction perpendicular to an axis of the flat or round wire and the insulated electric conductor being stretched by 20%, is at most 2 mm as measured in a direction of a conductor axis.

62. The winding wire according to claim 61, wherein the insulating layer adheres directly to the oxide-layer-free exterior surface as a result of application under a protective gas atmosphere.

63. The winding wire according to claim 61, wherein the insulating layer has a thickness between 30 m and 1000 m.

64. The winding wire according to claim 61, wherein the insulating layer is an extrusion coated layer on the oxide-layer-free exterior surface.

65. The winding wire according to claim 61, wherein the insulating layer consists of polyaryletherketone [PAEK].

66. The winding wire according to claim 65, wherein the polyaryletherketone [PAEK] is selected from the group consisting of: polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK], and combinations thereof.

67. The winding wire according to claim 61, wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulating layer being cut circumferentially in a direction perpendicular to an axis of the flat or round wire and the insulated electric conductor being stretched by 20%, is at most 1 mm as measured in a direction of a conductor axis.

68. A winding wire for electrical machines, comprising: a flat or round wire made of copper, aluminum, or a copper alloy, the flat or round wire having an exterior surface that is free of an oxide layer; and an insulating layer adhering directly to the oxide-layer-free exterior surface to form a coating around the oxide-layer-free exterior surface, the insulating layer being made of at least one thermoplastic material which provides electrical insulation; wherein the at least one thermoplastic material is polyetheretherketone [PEEK]; wherein the flat or round wire is designed to conduct an electrical current; wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulating layer being cut circumferentially in a direction perpendicular to an axis of the flat or round wire and the insulated electric conductor being stretched by 20%, is at most 1 mm as measured in a direction of a conductor axis.

69. The winding wire according to claim 68, wherein the insulating layer adheres directly to the oxide-layer-free exterior surface as a result of application under a protective gas atmosphere.

70. The winding wire according to claim 68, wherein the insulating layer has a thickness between 30 m and 1000 m.

71. The winding wire according to claim 68, wherein the insulating layer is an extrusion coated layer on the oxide-layer-free exterior surface.

72. The winding wire according to claim 68, wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulating layer being cut circumferentially in a direction perpendicular to an axis of the flat or round wire and the insulated electric conductor being stretched by 20%, is at most 0.2 mm as measured in a direction of a conductor axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the present disclosure and wherein similar reference characters indicate the same parts throughout the views.

[0078] FIG. 1 shows a schematic representation of a method according to an embodiment of the present disclosure;

[0079] FIG. 2a shows a first embodiment of an insulated electric conductor with a rectangular cross-section;

[0080] FIG. 2b shows a second embodiment of an insulated electric conductor with a rectangular cross-section.

[0081] FIG. 2c shows a third embodiment of an insulated electric conductor with a rectangular cross-section;

[0082] FIGS. 3a-3c show the first to third embodiment with a round cross-section.

DETAILED DESCRIPTION

[0083] The following description of technology is merely exemplary in nature of the subject matter, manufacture and use of one or more inventions, and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in such other applications as may be filed claiming priority to this application, or patents issuing therefrom. The following definitions and non-limiting guidelines must be considered in reviewing the description of the technology set forth herein.

[0084] In the following detailed description numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be understood by those skilled in the art that the present disclosure may be practiced without these specific details. For example, the present disclosure is not limited in scope to the particular type of industry application depicted in the figures. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present disclosure.

[0085] The headings and sub-headings used herein are intended only for general organization of topics within the present disclosure and are not intended to limit the disclosure of the technology or any aspect thereof. In particular, subject matter disclosed in the Background may include novel technology and may not constitute a recitation of prior art. Subject matter disclosed in the Summary is not an exhaustive or complete disclosure of the entire scope of the technology or any embodiments thereof. Classification or discussion of a material within a section of this specification as having a particular utility is made for convenience, and no inference should be drawn that the material must necessarily or solely function in accordance with its classification herein when it is used in any given composition.

[0086] The citation of references herein does not constitute an admission that those references are prior art or have any relevance to the patentability of the technology disclosed herein. All references cited in the Detailed Description section of this specification are hereby incorporated by reference in their entirety.

[0087] FIG. 1 shows a schematic representation of a method for producing an insulated electric conductor, as shown in FIGS. 2a to 2d and 3a to 3d. The insulated electric conductor comprises an electric conductor 1 made of copper, wherein other materials such as aluminum are conceivable, and an insulating coating 2, which has at least one insulating layer 3 made of thermoplastic material (also called thermoplastic resin, thermoplastic synthetic material or thermoplastic polymer), preferably a high-temperature-resistant plastic. In the following exemplary embodiments, the at least one insulating layer 3 is formed as an outer insulating layer 3 and thus forms the outermost layer of the insulating coating 2. It is understood, however, that in alternative embodiment variants still one or more further layers, preferably insulating layers, may be applied to the insulating layer 3, which can then form the outermost layer of the insulating coating 2.

[0088] The electric conductor 1 is continuously supplied in the illustrated embodiment as a band or wire via a coil outlet 7 to the process and can be prepared for example by means of cold forming processes, such as drawing or rolling, or extrusion, for example by means of Conform technology. It goes without saying that the method according to the present disclosure can also be carried out in-line, i.e. directly connected to the production process. In a first step, the electric conductor 1 is pre-cleaned mechanically in a pre-cleaning unit 8, for example by means of a grinding process, or chemically, for example by means of suitable solvents or acids, in order to remove coarse soiling from the electric conductor 1.

[0089] In the next method step, the pre-cleaned electric conductor 1 enters a plasma treatment unit 9 in which a protective gas atmosphere of nitrogen, argon or hydrogen is present and a gas plasma in the form of a low-pressure plasma is produced with less than 20 mbar pressure. However, a low-pressure plasma can already be produced even at a pressure of less than 80 mbar. In this low-pressure plasma, the surface of the electric conductor 1 is bombarded with ions of the protective gas in order to carry off or remove an oxide layer formed on a surface of the electric conductor 1. At the same time, the electric conductor 1 is soft-annealed by the plasma treatment and the surface energy of the electric conductor 1 therefore increases, thus activating the surface.

[0090] By removing the oxide layer and any contaminants from the surface of the electric conductor 1, wherein it may even be provided that very thin layers of the electric conductor 1 itself are removed from the surface, and by the increase of the surface energy, the adhesion between the electric conductor 1 made of copper and the insulating coating 2 applied to the electric conductor 1 can be improved decisively.

[0091] In the first embodiment variant of the insulated electric conductor according to the present disclosure, shown in FIG. 2a as a flat conductor with a rectangular cross-section and in FIG. 3a with a round cross-section, the insulating coating 2 consists only of an insulating layer 3. The insulating layer 3 has a temperature resistance of more than 180 C., preferably above 220 C., so that the insulated electric conductor can be used even at high operating temperatures. The outer insulating layer 3 consists of polyetheretherketone [PEEK], which has both high temperature resistance and high resistance to a large number of organic and inorganic substances. Alternatively, the outer insulating layer 3 may also consist of polyphenylene sulfide [PPS] or comprise PEEK and/or PPS.

[0092] In order to achieve the increased adhesion between the electric conductor 1 and the outer insulating layer 3, the electric conductor 1 reaches the extrusion unit 11 after passing through the plasma treatment unit 9, in which the outer insulating layer 3 is extrusion-coated onto the electric conductor 1. In this case, the electric conductor 1 is preheated to a temperature of at least 200 C., preferably at least 300 C. In order to prevent the re-formation of an oxide layer, both the extrusion and the transport of the conductor 1 into the extrusion unit 11 takes place under a protective gas atmosphere. An insulated electric conductor produced in this way can be used, for example, as a winding wire, which is also known in English as a magnet wire, in an electric machine, such as an electric motor or a transformer. The thickness of the outer insulating layer 3 is about 30 m in the present exemplary embodiment.

[0093] In particular, when the insulating layer 3 consists of a polyaryletherketone [PAEK], such as polyetheretherketone [PEEK], particularly good adhesion properties are achieved. Thus, the detachment of the insulating layer 3 from the electric conductor 1 usually remains well below 1 mm, and is in particular at most 0.2 mm, preferably at most 0.1 mm, more preferably at most 0.05 mm, particularly preferably at most 0.01 mm. Even if the thermoplastic material of the insulating layer 3 is polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS], increased adhesion properties can be achieved.

[0094] In general, the at least one insulating layer 3 may also comprise two, three, four or more individual insulating layers 3, all of which are produced under a protective gas atmosphere in the extrusion unit 11. As a result, the probability of defects in the insulating coating 2 can be drastically reduced, since defects in the lowermost of the insulating layers 3 are compensated by subsequent insulating layers 3. Tandem extrusion processes are particularly suitable for such a preparation.

[0095] Additionally or instead, it may also be provided that further insulating layers, which are preferably constructed analogously to the at least one insulating layer 3, i.e. in particular of a polyaryletherketone [PAEK] such as polyetheretherketone [PEEK] or another of the aforementioned plastics, are applied to the insulating coating 2 outside the protective gas atmosphere in a further extrusion unit 12.

[0096] In order to increase the adhesion between the insulating coating 2 and the electric conductor 1 as an alternative to the first embodiment variant, the insulating coating 2 comprises in the second embodiment shown in FIGS. 2b and 3b, in addition to the outer insulating layer 3 made of PEEK or PPS, a plastic-containing intermediate layer in form of a plasma polymer layer 4. This plasma polymer layer 4 is produced in the method according to the present disclosure in a plasma polymerization unit 10, which is arranged after the plasma treatment unit 9 and before the extrusion unit 11. It is also conceivable that the plasma treatment and the plasma polymerization are carried out in a combined device. In the plasma polymerization unit 10, after the oxide layer is removed and surface energy increased, as above, the plasma polymer layer 4 is formed on the surface of the electric conductor 1 by activating a gaseous monomer such as ethylene, butenol, acetone or tetrafluoromethane [CF.sub.4] by the plasma and thereby forming highly cross-linked macromolecules of different chain length and a proportion of free radicals, which deposit as a plasma polymer layer 4 on the surface of the electric conductor 1. In the present exemplary embodiment, the resulting plasma polymer layer 4 is less than 1 m thick and adheres particularly well to the activated and oxide-free surface of the electric conductor 1.

[0097] The outer insulating layer 3 is in turn extruded in the extrusion unit 11 onto the plasma polymer layer 4 as described above, wherein the adhesion between the plasma polymer layer 4 and the outer insulating layer 3 is also high.

[0098] In the third embodiment variant, illustrated in FIGS. 2c and 3c, the insulating coating 2 comprises, in addition to the outer insulating layer 3 made of PEEK, a plastic-containing intermediate layer formed as a fluoropolymer layer 5 of polytetrafluoroethylene [PTFE] or perfluoroethylene propylene [FEP], which is applied directly to the surface of the electric conductor 1 and further improves the adhesion between the electric conductor 1 and the outer insulating layer 3. The fluoropolymer layer 5 is produced together with the outer insulating layer 3 in the extrusion unit 11 by means of a co-extrusion or tandem extrusion process. The thickness of the fluoropolymer layer 5 is about 30 m in the present embodiment.

[0099] After extrusion-coating the outer insulating layer 3, the insulated electric conductor is cooled in a controlled manner, for example by air cooling, and passed over a series of pressure rollers which further improve adhesion by applying pressure to the insulated electric conductor. Finally, the insulated electric conductor is wound on a coil winder 13.

[0100] The illustrated devices in FIG. 1 concern an overview in which all devices are shown, which are necessary for the production of the individual embodiment variants. While the sequence, from right to left, of the devices passed through are independent of the embodiment variant and in any case the plasma treatment unit 9 and the extrusion unit 11 have to be passed, the plasma polymerization unit 9 and the further extrusion unit 12 are optional devices which are used only in the production of specific design variants. It is understood that instead of a co-extrusion or tandem extrusion process, several individual extrusions can be carried out sequentially.

[0101] The preferred embodiments of the present disclosure have been described above to explain the principles of the present disclosure and its practical application to thereby enable others skilled in the art to utilize the present disclosure. However, as various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the present disclosure, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings, including all materials expressly incorporated by reference herein, shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present disclosure should not be limited by the above-described exemplary embodiment but should be defined only in accordance with the following claims appended hereto and their equivalents.

LIST OF REFERENCE NUMERALS

[0102] 1 Electric conductor [0103] 2 Insulating coating [0104] 3 Insulating layer [0105] 4 Plasma polymer layer [0106] 5 Fluoropolymer layer [0107] 6 Metal layer [0108] 7 Coil outlet [0109] 8 Precleaning unit [0110] 9 Plasma treatment unit [0111] 10 Plasma polymerization unit [0112] 11 Extrusion unit [0113] 12 Further extrusion unit [0114] 13 Coil winder