Patent Application
20140110145
The disclosed invention relates generally to an anodized conductor and method of making the anodized conductor. More particularly, the disclosed invention relates to a composite conductor having a copper core and an anodized aluminum dielectric layer over-coated with a second anodized aluminum layer and method for making same through post-metallic coating.
The insulation of electrically conductive wire used to form a coil or similar conductive article is generally established and may be undertaken by a number of methods, including the fundamental approaches of coating with an organic polymerized material or anodization. With respect to the first approach, any one of several organic wire coatings selected from the group consisting of plastics, rubbers and elastomers will provide effective insulation on conductive material. However, while these materials demonstrate good dielectric properties and have the ability to withstand high voltages, they are compromised by their poor operating performance at temperatures above 220° C. as well as by their failure to effectively dissipate ohmic or resistance heating when used in coil windings. (Inorganic insulation such as glass, mica or certain ceramics, tolerates temperatures greater than 220° C. but suffer from being too brittle for most applications.)
In addition to coating conductive material with an organic substance electrically conductive materials such as copper and aluminum may be anodized to provide some measure of insulation. In the case of a copper core, the anodization of this material is known to produce unsatisfactory results due to cracking. It is possible to electroplate copper with aluminum but this approach generally produces undesirable results in terms of durability of the coating. In the case of an aluminum core, copper can be plated on the core but results in unsatisfactory electrical efficiency.
An electrically insulated conductor for carrying signals or current having a solid or stranded copper core of various geometries with only a single electrically insulating and thermally conductive layer of anodized aluminum (aluminum oxide) is disclosed in U.S. Pat. No. 7,572,980. As described in the '980 patent, the device is made by forming uniform thickness thin sheet or foil of aluminum to envelop the copper conductive alloy core. The aluminum has its outer surface partially anodized either before or after forming to the core in an electrolytic process to form a single layer of aluminum oxide.
This and other examples of the known art represent improvements in the coating of wire and other forms of electrical transmission. However, as in so many areas of technology, there is room in the art of wire coating for further advancement.
The disclosed invention advances electric conductor technology and overcomes several of the disadvantages known in the prior art. Particularly, the disclosed invention provides an insulated electrical composite conductor having a copper core, a layer of aluminum formed on the copper core, and a second layer of aluminum in the form of a high-purity aluminum. The copper core may be a solid core or may be formed from a plurality of copper strands.
The layer of aluminum formed over the copper core is at least partially anodized to form an aluminum oxide dielectric layer. The layer of high-purity aluminum may be formed by evaporation deposition, sputter deposition, or co-extrusion. Once the layer of high-purity aluminum is formed, it is anodized. More than two layers of aluminum may be formed over the copper core.
The electric conductor of the disclosed invention may be useful in a broad variety of applications where coiled wire or similar conductive material is required, such as for vehicle generators, alternators and for subsystems related to generators, alternators and regulators. Accordingly, the disclosed invention may be useful in the manufacture of both internal combustion vehicles as well in hybrid vehicles and systems for hybrid vehicles. Furthermore, the disclosed invention may find application in any electrical motor that requires very high voltage, effective heat dissipation and high temperature operation. Accordingly, the disclosed invention may find application in the locomotive and aerospace industries as well as in the automotive vehicle industry.
The above advantages and other advantages and features will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings.
For a more complete understanding of this invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention wherein:
In the following figures, the same reference numerals will be used to refer to the same components. In the following description, various operating parameters and components are described for different constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting.
With respect to
With particular reference to
According to the disclosed invention, the composite conductor 10 may be further insulated to achieve a high uniform electrical breakdown and thus expand the utility of electrically conductive composite wire beyond the range previously known. This is achieved by adding a layer of high-purity aluminum. The high-purity aluminum is the result of the refining of aluminum to remove impurities resulting in purity of at least 99.99%. The layer of high-purity aluminum, illustrated as 20 in
Referring to
With reference to
Regardless of the structure of the copper or copper alloy core or the shape, the high-purity aluminum coating of the composite conductor of the disclosed invention may be formed by alternative techniques.
Referring to
Once the aluminum layer envelops the copper core at step 102 the outer surface of the aluminum is partially anodized at step 104. This is done using an electrolytic process to form a single homogeneous dielectric layer. It is preferred though not required that the outer layer is only partially anodized thus leaving a thin layer of aluminum in contact with the copper core. In addition, the step of anodizing the aluminum may be undertaken before being applied to the copper core.
At step 106 the anodized aluminum may be rinsed according to an optional step of the disclosed invention. Rinsing of the anodized aluminum stops the anodization process by removing the electrolytic solution.
A further optional step arises at step 108 in which the conductor, now a composite, is annealed. The annealing process reduces or eliminates stresses that may be present in the core, the aluminum layer, the dielectric aluminum oxide layer, or between layers.
Once the aluminum layer has been anodized and optionally rinsed and annealed an overcoating of high-purity aluminum is made at step 110. As will be set forth below, the overcoating of high-purity aluminum may be done by any of several ways, including but not limited to co-extrusion, vacuum evaporation and sputter deposition.
The layer of high-purity aluminum, once applied by any method, is anodized at step 112. At step 114 the anodized composite conductor is again optionally rinsed to remove any residual electrolytic fluid and to thus fully halt the anodization process. At step 116 the rinsed conductor is optionally again annealed.
As noted, at 110 the composite conductor is overcoated with a layer of high-purity aluminum. The overcoating step may be accomplished through several methods although three methods—to co-extrusion, vacuum evaporation and sputter deposition—are preferred.
Referring to
At least partially submerged in the electrolyte solution 130 is a guide roller 132. The guide roller 132 guides the wire 122 into and out of the solution 130. The voltage across the terminals 126 and 128 causes an electric current to run through the solution 130, thereby effecting a chemical reaction of the solution 130 with the outer surface of the aluminum. The reaction results in the formation of a dielectric layer of aluminum oxide.
Another guide roller 134 is provided to guide the anodized wire 122 out of the solution 130. At this point the wire 122 may optionally pass through a rinse (not shown) followed by the step of being optionally annealed (also not shown).
An overcoating unit 136 is provided to apply the layer of high-purity aluminum to the anodized wire 122. According to the embodiment shown in
Once overcoated with high-purity aluminum, the overcoated and anodized wire 122 is directed to a second electrolyte solution 140. A guide roller 142 guides the wire into and out of the electrolyte solution 140. A power supply 144 has a negative terminal 146 connected to the wire 122 and a positive terminal 148 connected to the electrolyte solution 140. The electrolyte solution 140 provides a bath for the wire 122. The voltage across the terminals 146 and 148 causes an electric current to run through the solution 140, thereby effecting a chemical reaction of the solution 140 with the outer surface of the high-purity aluminum. The reaction results in the formation of a second dielectric layer of aluminum oxide.
The overcoated wire 122 is guided out of the solution 140 by a guide roller 150. Optionally the wire 122 may be rinsed in a bath 152 to remove any residual electrolyte solution after being guided into and out of the bath 152 by a guide roller 154. The rinsed wire 122 is taken up on a reel 156.
As noted, according to the disclosed invention the high-purity aluminum coating may be overcoated on the wire 122 by other methods. Of no particular order the second of these methods is illustrated in
The foregoing discussion discloses and describes exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.
