Patent Description:
Automotive cables, such as a battery cable, can include an aluminum conductor which can be lighter and less expensive than conventional copper conductors. A contact element, such as a ring terminal, is crimped or otherwise secured to a bare end of the aluminum conductor to form a terminated end. The contact element is typically made from copper based alloys such as brass, for example, or another material that is different than aluminum.

The bare end of aluminum conductor, however, can be susceptible to oxidation (e.g., sapphire oxidation) which can inhibit conductivity between the bare end and the contact element and thus can prevent proper termination with a contact element. The aluminum conductor can also be susceptible to galvanic corrosion when it is terminated to a material that is more basic than aluminum, such as brass, and when moisture is present at the interface between the conductor and the contact element. The galvanic corrosion can cause aluminum dissolution which can adversely affect the conductivity between the aluminum conductor and the contact element. Once terminated, the aluminum conductor can be more susceptible to mechanical creep at its terminated end at low temperatures (e.g., <NUM> degrees C) than conventional copper conductors which can result in undesirable impedances. The aluminum conductor is also weaker than a copper conductor which can result in the aluminum conductor being easier to pull out of the contact element after termination.

<CIT> discloses a method relating to the preamble of claim <NUM> and more specifically it discloses an aluminum electric wire (<NUM>) with a female terminal fitting (<NUM>) comprising an electric wire (<NUM>) with a metal core (<NUM>) covered by an insulation sheath (<NUM>); a terminal fitting (<NUM>) provided with an electric wire connecting section (<NUM>) that is connected to the core (<NUM>) and made from a different type of metal than the core (<NUM>); and a thin adherend (<NUM>) made of metal that has similar ionization tendencies to the terminal fitting (<NUM>) and that is attachable from an end where the core (<NUM>) has been exposed by the peeling away of the insulation sheath (<NUM>) on the electric wire (<NUM>) to an end where the insulation sheath (<NUM>) remains intact. The adherend (<NUM>) is formed by winding copper foil in a plurality of layers. The adherend (<NUM>) is bonded to the core (<NUM>) of the electric wire (<NUM>) by ultrasonic welding and the electric wire connecting section (<NUM>) of the terminal fitting (<NUM>) is crimped to the adherend (<NUM>).

<CIT> discloses a method involving sliding a metal sleeve (<NUM>), that is tinned at least on its inside, over a stripped end (<NUM>) of the cable, and metallically tinned by ultrasonic tinning with the conductors (<NUM>) at the end of the cable. A metal tinned contact terminal (<NUM>) is placed over the tinned end of the cable and pressed. An independent claim is included for a connection for contacting and fixing a cable.

The invention is defined by the independent claims <NUM> and <NUM>.

It is believed that certain embodiments will be better understood from the following description taken in conjunction with the accompanying drawings in which:.

In connection with the views and examples of <FIG>, wherein like numbers indicate the same or corresponding elements throughout the views, <FIG> illustrates a wire <NUM> having a conductor <NUM> and an insulating layer <NUM> surrounding the conductor <NUM>. A portion of the insulating layer <NUM> is shown to be removed from the conductor <NUM> to expose a bare portion <NUM> of the conductor <NUM>. The insulating layer <NUM> can be removed with any of a variety of suitable methods, such as through interaction with a set of wire strippers. Although a multi-strand insulated conductor is shown, it will be appreciated that any of a variety of suitable alternative conductors can be used having different quantities/sizes of strands, including a conductor having an individual strand (e.g., a solid conductor) and/or being devoid of insulation (e.g., a grounding conductor.

As illustrated in <FIG> and <FIG>, a conductive foil layer <NUM> is attached to a portion of the bare portion <NUM> of the conductor <NUM>. In one embodiment, the conductive foil layer <NUM> can be wrapped around the bare portion <NUM> of the conductor <NUM>, as illustrated in <FIG>, and pressure can be applied to the conductive foil layer <NUM> (in the direction of the arrows P). In one embodiment, the application of pressure to the conductive foil layer <NUM> can be the result of simply overlying the conductive foil layer <NUM> onto the bare portion <NUM> of the conductor <NUM> (e.g., by grasping the ends of the conductive foil layer <NUM> and wrapping it around the bare portion <NUM>). In certain embodiments, the desired pressure can be applied by hand, with a tool (e.g., pliers), or any of a variety of other suitable methods.

Once the conductive foil layer <NUM> has been provided onto the bare portion <NUM> of the conductor <NUM>, the bare portion <NUM> of the conductor <NUM> and the conductive foil layer <NUM> are joined together. In one embodiment according to the present invention, the bare portion <NUM> and the conductive foil layer <NUM> are joined together through welding, such as through ultrasonic welding, for example. Welding the bare portion <NUM> and the conductive foil layer <NUM> together can bond the conductive foil layer <NUM> to the conductor <NUM> as well as bond the strands of the conductor <NUM> together to form an amalgamated mass (e.g., a nugget). Welding can also help break apart any oxidation formed on the conductor <NUM> that might adversely affect the conductivity between the conductor <NUM> and the conductive foil layer <NUM>. Welding can accordingly enhance the conductivity characteristics between the conductor <NUM> and the conductive foil layer <NUM>.

Once the conductor <NUM> and the conductive foil layer <NUM> have been joined together, a terminal <NUM> is slid over the conductive foil layer <NUM> and secured to the amalgamated mass of the bare portion <NUM> and the conductor <NUM>, such as with a crimping tool, for example, to create a terminated wire <NUM>, as illustrated in <FIG> and <FIG>. In one embodiment, as illustrated in <FIG>, an exterior surface <NUM> of a crimping portion <NUM> of the terminal <NUM> can be reinforced, such as by applying solder <NUM> at a separation point <NUM> of the crimping portion <NUM>, to enhance the durability of the connection between the terminal <NUM> and the conductor <NUM>. In certain embodiments, the terminal <NUM> can be nickel plated, or plated with another conductive material, prior to attachment of the terminal <NUM> to the conductor <NUM>. In such an embodiment, the nickel plating can protect the terminal from galvanic corrosion to enhance the conductivity between the conductor <NUM> and the material that forms the terminal <NUM> (e.g., brass). The terminated end can additionally or alternatively be dipped in molten solder to enhance durability of the terminated wire <NUM>. It is to be appreciated that although the terminal <NUM> is shown to be a ring terminal, it is to be appreciated that any of a variety of suitable alternative contact elements, such as a slotted terminal, a bus bar, or a termination block, for example, can be attached to the wire <NUM>. It is also to be appreciated that the terminated wire <NUM> is contemplated for use in a variety of suitable applications, such as, for example, as a vehicular battery cable.

The conductor <NUM> and the conductive foil layer <NUM> are formed of different conductive materials with the conductive foil layer <NUM> having about the same or higher conductivity than the conductor <NUM>. As a result, when the conductive foil layer <NUM> is interposed between the conductor <NUM> and the terminal <NUM>, the conductive foil layer <NUM> can enhance the overall conductivity between the conductor <NUM> and the terminal <NUM> as compared to the conductive foil layer <NUM> not being present (i.e., the conductor <NUM> and the terminal <NUM> being entirely in contact with each other). In one embodiment according to the present invention, the conductor <NUM> is formed of aluminum or an aluminum alloy, the conductive foil layer <NUM> is formed of copper, and the terminal <NUM> can be formed of brass. In such an embodiment, the copper of the conductive foil layer <NUM> can allow the interaction between the aluminum conductor <NUM> and the brass terminal <NUM> to be more conductive than crimping the brass terminal <NUM> directly to the aluminum conductor <NUM> (which in some instances can be non-conductive). It is to be appreciated that the conductive foil layer <NUM> can be formed of a material that is, in examples not according to the present invention, as conductive as or, in embodiments according to the present invention, more conductive than the conductor <NUM>. In certain embodiments according to the present invention, the conductor <NUM> can be formed of a conductive material having a conductivity of about <NUM>*<NUM><NUM> S/m (at <NUM> degrees C) or less, and the conductive foil layer <NUM> can be formed of conductive material having a conductivity of about <NUM>*<NUM><NUM> S/m (at <NUM> degrees C) or more. In other embodiments which are reported here for illustrative purposes, the conductor <NUM> can be formed of a conductive material that is substantially susceptible to oxidation, such as an aluminum alloy, a chromium alloy, and/or a magnesium alloy, and the conductive foil layer <NUM> can be formed of conductive material that is not substantially susceptible to oxidization such as a copper alloy, silver, nickel, and/or gold.

As illustrated in <FIG>, the conductive foil layer <NUM> is shown to have a length L1, a width W, and a thickness T and the bare portion <NUM> of the conductor <NUM> is shown to have a length L2, a diameter D, and a circumference C. In one embodiment which is not according to the present invention, the length L1 and width W of the conductive foil layer <NUM> can be less than the circumference C and the length L2 of the bare portion <NUM> of the conductor <NUM>, respectively, such that when the conductive foil layer <NUM> is attached to the conductor <NUM>, the conductive foil layer <NUM> neither reaches the end of the conductor <NUM> nor completely surrounds it. According to the present invention, the length L1 of the conductive foil layer <NUM> is more than the circumference C of the bare portion <NUM> of the conductor <NUM>, respectively, such that when the conductive foil layer <NUM> is attached to the conductor <NUM>, the conductive foil layer <NUM> overlaps at its ends such that it entirely surrounds the bare portion <NUM>. In certain embodiments, the diameter D of the conductor can be significantly more than the thickness T of the conductive foil layer <NUM>, and can in certain embodiments have a ratio of between about <NUM>:<NUM> and about <NUM>:<NUM> and in certain embodiments can have a ratio of about <NUM>:<NUM>. In one embodiment, for a <NUM> AWG wire, the length L1 can be about <NUM>, the width W can be about <NUM>, the thickness T can be about <NUM>, the length L2 can be about <NUM>, the diameter D can be about <NUM>, and the circumference C can be about <NUM>. It will be appreciated that a layer described herein as being a foil, such as conductive foil layer <NUM>, should be understood to mean that the layer is a sheet-like substrate having a length and width that are substantially greater than the thickness of the substrate. In certain embodiments, ratio of the combined length and width of the layer to the thickness of the layer can be between about <NUM>:<NUM> to about <NUM>,<NUM>:<NUM>. In certain embodiments, the ratio can be about <NUM>,<NUM>: <NUM> to about <NUM>,<NUM>: <NUM> and preferably about <NUM>,<NUM>:<NUM>.

In some embodiments, the bare portion <NUM> of the conductor <NUM>, alone or in combination with the conductive foil layer <NUM>, can be cleaned before or after application of the conductive foil layer <NUM> to remove any oxides on the conductor <NUM> and/or between the conductor <NUM> and the conductive foil layer thus enhancing the effectiveness of the conductivity between the conductor <NUM>, the conductive foil layer <NUM>, and the terminal <NUM>. In one embodiment, the conductor <NUM> and/or conductive foil layer <NUM> can be cleaned via a plasma treatment performed by a blown-ion air system (not shown). The blown-ion air system can force pressurized air towards an electrode, through a narrow nozzle, and onto the bare portion <NUM>. The electrode creates positively charged ions in the pressurized air which is then accelerated by the nozzle and provided onto the bare portion <NUM> of the conductor <NUM>. The positively charged ions in the airstream positively charge the outer surface of the bare portion <NUM> thereby increasing its surface energy to remove any oxides. In another embodiment, the conductor <NUM> and/or conductive foil layer <NUM> can be cleaned via a high temperature induction heating process that applies a flame to the conductor <NUM> and/or conductive foil layer <NUM> using any of a variety of fuels, such as, for example, hydrogen gas, alcohol, and/or acetylene.

In certain embodiments which are not according to the present invention and are reported here for illustration purposes only, the bare portion <NUM> of the conductor <NUM> and the conductive foil layer <NUM> can be joined by soldering such as by dipping the bare portion <NUM> and the conductive foil layer <NUM> together in a molten material (e.g., such as molten tin) or resistance soldering the bare portion <NUM> and the conductive foil layer <NUM> together, for example, both of which can enhance the conductivity between the bare portion <NUM>, the conductive foil layer <NUM>, and the terminal <NUM>. It is to be appreciated that cleaning the bare portion <NUM> and/or the conductive foil layer <NUM> can encourage the application of solder. However, the soldering can be performed in addition to the welding or in addition to or in lieu of the cleaning described above. It is also to be appreciated that the bare portion <NUM> and/or the conductive foil layer <NUM> can undergo any of a variety of other suitable treatment processes to prepare for affixation of the terminal <NUM>.

<FIG> illustrate an embodiment which is not according to the present invention and is presented here for illustration purposes only. This embodiment relates to a wire <NUM>, a conductive foil layer <NUM> and a terminal <NUM> that are similar to, or the same in many respects as, the wire <NUM>, the conductive foil layer <NUM> and the terminal <NUM>, respectively, illustrated in <FIG>. For example, the wire <NUM> can include a conductor <NUM>, an insulating layer <NUM>, a bare portion <NUM>, and a conductive foil layer <NUM>. However, the conductive foil layer <NUM> can be joined to the bare portion <NUM> of the conductor <NUM> by applying pressure to the conductive foil layer <NUM> (in the direction of the arrows P) and without any welding (ultrasonic or otherwise). In such an arrangement, the terminal <NUM> can be slid over the bundle of strands (e.g., <NUM>) at the bare portion <NUM> and secured to the bundle of strands (e.g., <NUM>), such as with a crimping tool, for example. An exterior surface <NUM> of a crimping portion <NUM> of the terminal <NUM> can be reinforced, such as by applying solder <NUM> at a separation point <NUM> of the crimping portion <NUM>.

<FIG> illustrates a wire <NUM>, a conductive foil layer <NUM> and a terminal <NUM> that are similar to, or the same, in many respects as the wire <NUM>, the conductive foil layer <NUM> and the terminal <NUM>, respectively, illustrated in <FIG>. For example, the wire <NUM> can include a conductor <NUM>, an insulating layer <NUM>, and a bare portion <NUM>. The conductive foil layer <NUM>, according to this invention, is a corrugated screen having a plurality of elevated portions (e.g., points) distributed along upper and lower surfaces (upper surface <NUM> shown). When the conductive foil layer <NUM> is attached to the bare portion <NUM> of the conductor <NUM>, the points can abrade the bare portion <NUM> of the conductor <NUM> (e.g., remove any oxidation) to facilitate effective electrical contact between the bare portion and the conductive foil layer <NUM>. If the bare portion <NUM> and the conductive foil layer <NUM> are joined by soldering, as described above, the solder can collect in pockets defined between the points to facilitate effective bonding between the bare portion <NUM> and the conductive foil layer <NUM>. In one embodiment, the conductive foil layer <NUM> can be formed of nickel and the conductor <NUM> can be formed of aluminum <NUM>.

<FIG> illustrate a wire <NUM> that is similar to, or the same, in many respects as the wire <NUM> illustrated in <FIG>. For example, the wire <NUM> can include a conductor <NUM>, an insulating layer <NUM>, and a bare portion <NUM>. According to embodiments not encompassed by the claims, a ferrule <NUM>, however, can be provided in lieu of, or in addition to, a conductive foil layer (e.g., <NUM>). The ferrule <NUM> can be joined to the bare portion similarly as described above and a terminal (not shown) can then be secured thereto.

Another alternative embodiment of a terminated wire (e.g., an alternative terminated wire) is also contemplated, which however is not according to the present invention. The alternative terminated wire can be similar in many respects to the terminated wire <NUM> described above except that the alternative terminated wire does not include a conductive foil layer (e.g., <NUM>). To prepare the alternative terminated wire, a portion of an insulating layer (e.g., <NUM>) can be removed from a conductor (e.g., <NUM>) to expose a bare portion (e.g., <NUM>) of the conductor (e.g., <NUM>). The bare portion can then be cleaned (e.g., with a plasma treatment) and welded (e.g., through ultrasonic welding) to bind individual strands of the conductor together.

The steps of cleaning and welding can be performed in any order. Once welded, the bare portion can be soldered (e.g., through tin dipping or resistive soldering). A terminal (e.g., <NUM>) can then be attached to the bare portion insulating layer to create the alternative terminated wire. In one embodiment, the conductor <NUM> can be formed of aluminum and the conductive foil layer can be formed of nickel.

Testing was conducted on a terminated wire similar to the terminated wire <NUM> described above. The terminated wire that was tested was a <NUM> AWG (<NUM>/<NUM>) aluminum wire having a bare portion (e.g., <NUM>) measuring about <NUM>, a copper conductive foil layer (e.g., <NUM>) having a length (e.g., L1) of about <NUM>, a width (e.g., W) of about <NUM>, and a thickness (e.g., T) of about <NUM>, and a brass terminal. The copper conductive foil layer was manually wrapped onto the bare portion and then was ultrasonically welded to form a nugget. A terminal was then crimped onto the nugget. Ten separate resistance tests were then performed to measure the resistance between the conductor and the terminal (e.g., between points A and B illustrated on <FIG>). Each test resulted in a resistance between <NUM> Ohms and <NUM> Ohms, having an example resistance of <NUM> Ohms. The maximum allowable resistance for use as a vehicular battery cable is <NUM> Ohms.

Comparative testing was also conducted to compare the results for different terminations of a <NUM> AWG (<NUM>/<NUM>) aluminum wire having a bare portion (e.g., <NUM>) measuring about <NUM>, a copper conductive foil layer (e.g., <NUM>) having a length (e.g., L1) of about <NUM>, a width (e.g., W) of about <NUM>, and a thickness (e.g., T) of about <NUM>, and a brass terminal. A variety of different terminated wires were assembled using certain of the methodologies described above and resistance tests were performed on the terminated wires. The results of the resistance tests are as follows:.

The foregoing description of embodiments and examples of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the forms described. Numerous modifications are possible in light of the above teachings. Some of those modifications have been discussed and others will be understood by those skilled in the art. The embodiments were chosen and described in order to best illustrate the principles of the disclosure and various embodiments as are suited to the particular use contemplated. The scope of the disclosure is, of course, not limited to the examples or embodiments set forth herein.

Claim 1:
A method for terminating a wire (<NUM>; <NUM>) with a contact element (<NUM>; <NUM>), the wire comprising a conductor (<NUM>; <NUM>) and an insulating layer (<NUM>; <NUM>) surrounding the conductor, the conductor being formed of aluminum or an aluminum alloy, the method comprising:
removing the insulating layer from the conductor to expose a portion (<NUM>; <NUM>) of the conductor, the exposed portion having a circumference;
installing a conductive foil layer (<NUM>; <NUM>) on the exposed portion of the conductor such that the conductive foil layer (<NUM>; <NUM>) entirely surrounds the circumference of the exposed portion of the conductor;
welding the conductive foil layer (<NUM>; <NUM>) and the exposed portion of the conductor together to form an amalgamated mass; and
installing the contact element (<NUM>; <NUM>) on the amalgamated mass, the contact element being formed of a different material than the conductor (<NUM>; <NUM>) and the conductive foil layer (<NUM>; <NUM>), wherein:
the conductive foil layer (<NUM>; <NUM>) is formed of copper,
the method being characterized in that the conductive foil layer (<NUM>) comprises a corrugated screen having a plurality of elevated portions distributed along upper and lower surfaces; and
when the conductive foil layer(<NUM>) is installed on the exposed portion (<NUM>), the elevated portions are configured to abrade the exposed portion (<NUM>) of the conductor (<NUM>) prior to the welding of the conductive foil layer (<NUM>) and the exposed portion.