Insulated Electric Conductor

Abstract

An insulated electric conductor includes 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. The flat or round wire is designed to conduct an electrical current.

Claims

1-53. (canceled)

54. An insulated electric conductor, 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 flat or round wire is designed to conduct an electrical current.

55. The insulated electric conductor according to claim 54, comprising more than one of said flat or round wire arranged in a strand, wherein the insulating layer adheres directly to the oxide-layer-free exterior surface of each flat or round wire to form the coating.

56. The insulated electric conductor 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.

57. The insulated electric conductor according to claim 54, wherein the insulating layer has a thickness between 10 μm and 1000 μm.

58. The insulated electric conductor according to claim 54, wherein the insulating layer is an extrusion coated layer on the oxide-layer-free exterior surface.

59. The insulated electric conductor according to claim 54, wherein the thermoplastic material is selected from the group consisting of: polyaryletherketone [PAEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS], and combinations thereof.

60. The insulated electric conductor according to claim 54, wherein the thermoplastic material is a polyaryletherketone [PAEK] selected from the group consisting of: polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK], and combinations thereof.

61. The insulated electric conductor according to claim 54, wherein the one or more electrically conductive materials include copper, aluminum, or a copper alloy.

62. The insulated electric conductor 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 insulated electric conductor being stretched by 20%, is at most 3 mm as measured in a direction of a conductor axis.

63. An insulated electric conductor, 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 insulating layer is applied under a protective gas atmosphere; wherein the flat or round wire is designed to conduct an electrical current.

64. The insulated electric conductor according to claim 63, wherein the insulating layer has a thickness between 30 μm and 1000 μm.

65. The insulated electric conductor according to claim 63, wherein the insulating layer is an extrusion coated layer on the oxide-layer-free exterior surface.

66. The insulated electric conductor according to claim 63, wherein the thermoplastic material is selected from the group consisting of: polyaryletherketone [PAEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS], and combinations thereof.

67. The insulated electric conductor according to claim 63, wherein the thermoplastic material is a polyaryletherketone [PAEK] selected from the group consisting of: polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK], and combinations thereof.

68. The insulated electric conductor according to claim 63, wherein the one or more electrically conductive materials include copper, aluminum, or a copper alloy.

69. The insulated electric conductor according to claim 63, wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulated electric conductor being stretched by 20%, is at most 1 mm as measured in a direction of a conductor axis.

70. An insulated electric conductor, 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 at least one insulating layer adhering directly to the oxide-layer-free exterior surface to form a coating around the oxide-layer-free exterior surface, the at least one insulating layer being made of at least one thermoplastic material that is selected from the group consisting of: polyaryletherketone [PAEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS], and combinations thereof, which at least one thermoplastic material provides electrical insulation; wherein the flat or round wire is designed to conduct an electrical current.

71. The insulated electric conductor according to claim 70, wherein a total thickness of the at least one insulating layer is between 30 μm and 1000 μm.

72. The insulated electric conductor according to claim 70, wherein the at least one insulating layer is an extrusion coated layer on the oxide-layer-free exterior surface.

73. The insulated electric conductor according to claim 70, wherein the thermoplastic material is a polyaryletherketone [PAEK] selected from the group consisting of: polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK], and combinations thereof.

74. The insulated electric conductor according to claim 70, wherein the one or more electrically conductive materials include copper, aluminum, or a copper alloy.

75. The insulated electric conductor according to claim 70, wherein the adhesion between the insulating layer and the oxide-layer-free exterior surface resists detachment such that said detachment, in response to the insulated electric conductor being stretched by 20%, is at most 3 mm as measured in a direction of a conductor axis.

76. The insulated electric conductor according to claim 70, wherein the at least one insulating layer adheres directly to the oxide-layer-free exterior surface as a result of application under a protective gas atmosphere.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0088] The invention will now be explained in more detail below with reference to exemplary embodiments. The drawings are provided by way of example and are intended to explain the concept of the invention, but shall in no way restrict it or even render it conclusively, wherein:

[0089] FIG. 1 shows a schematic representation of a method according to the invention;

[0090] FIG. 2a shows a first embodiment variant of an insulated electric conductor with a rectangular cross-section;

[0091] FIG. 2b shows a second embodiment variant of an insulated electric conductor with a rectangular cross-section.

[0092] FIG. 2c shows a third embodiment variant of an insulated electric conductor with a rectangular cross-section;

[0093] FIGS. 3a-3c show the first to third embodiment variant with a round cross-section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0094] 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.

[0095] 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 invention 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.

[0096] 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.

[0097] 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.

[0098] In the first embodiment variant of the insulated electric conductor according to the invention, 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.

[0099] 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 μm in the present exemplary embodiment.

[0100] 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 m 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 [RAI], polyetherimide [PEI], polyphenylene sulfide [PPS], increased adhesion properties can be achieved.

[0101] 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.

[0102] 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.

[0103] 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 invention 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 μm thick and adheres particularly well to the activated and oxide-free surface of the electric conductor 1.

[0104] 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.

[0105] 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 μm in the present embodiment.

[0106] 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.

[0107] 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.

LIST OF REFERENCE NUMERALS

[0108] 1 Electric conductor [0109] 2 Insulating coating [0110] 3 Insulating layer [0111] 4 Plasma polymer layer [0112] 5 Fluoropolymer layer [0113] 6 Metal layer [0114] 7 Coil outlet [0115] 8 Precleaning unit [0116] 9 Plasma treatment unit [0117] 10 Plasma polymerization unit [0118] 11 Extrusion unit [0119] 12 Further extrusion unit [0120] 13 Coil winder