Patent Application
20210249805
The present invention relates to electrical connectors in adverse environments.
Electrical connectors for use in harsh environments are typically designed to exclude the environment from the electrical contacts to prevent the environment from degrading the contact material or shorting connected electronics. The harsh environment may degrade the electrical contact by corroding the electrical contact or otherwise reacting with the electrical contact. In one example, the electrical connector may use a set of gaskets, seals, and/or oil filled bladders to exclude the environment from the electrical contacts. Additional precautions may be taken for wet environments that provide a conduction path outside of the intended electrical connection. The outside conduction path may provide an additional method of corrosion of the electrical contact, further degrading the electrical connection.
In one example of conventional connectors, the contact material may be formed from a relatively exotic material that does not react with the expected environment, or reacts with the expected environment in a predictable and manageable way. However, connectors with exotic materials and/or complex sealing systems may incur additional costs to manufacture and/or service. Additionally, some exotic materials may have undesirable properties, such as brittleness, that present additional issues with manufacturing and/or using the electrical connector.
The techniques presented herein provide for an electrical connector comprising an electrically insulating body and a self-passivating contact held at a higher voltage than a non-passivating contact. The self-passivating contact comprises a first electrically conductive material that forms an electrically insulating passivation layer when exposed to water. The non-passivating contact comprises a second electrically conductive material that may or may not form a passivation layer when exposed to water.
The use of self-passivating material in contacts for electrical connectors in adverse environments, such as an underwater environment, provides an important tool for protecting against corrosion driven by an applied voltage between the contacts of the electrical connector. As described herein, contacts are electrically conducting materials that are formed to make electrical connections with other contacts in, e.g., another electrical connector. More specifically, an anodic contact, or anode, is used to describe a contact that is held at a higher electric potential than a cathodic contact, or cathode, in the same environment. Holding the anode at a higher electric potential biases the material in the anode to be oxidized by the environment, and the material in the cathode to be reduced by the environment. Self-passivating materials typically react with an adverse environment by forming a thin passivation layer on the surface of the material. In one example, the self-passivating material may react with water, either liquid or vapor, in the adverse environment to form the passivation layer. The passivation layer is typically non-reactive with the environment and protects the bulk of the material from further reactions with the environment. In another example, the self-passivating material may be electrically conductive, while the passivation layer may be electrically insulating to prevent electrical conduction through the self-passivating material into the adverse environment.
Some examples of materials that are self-passivating in water include niobium, tantalum, titanium, zirconium, molybdenum, ruthenium, rhodium, palladium, hafnium, tungsten, rhenium, osmium, and iridium. Each of these materials react with water to form an electrically insulating passivation layer when exposed to a water environment. The passivation layer may be oxides, hydroxides, or other compounds that form by reacting the self-passivating material with an adverse environment. Self-passivating materials may also be more expensive than other materials, such as copper, which are typically used for electrical contacts.
While the anodic (i.e., positive) contact in an electrical connector may be formed from a self-passivating material to protect against corrosion driven by the applied voltage, the cathodic (i.e., negative) contact does not necessarily have to be made from the same self-passivating material. Since the electrically driven corrosion occurs at the anode, the cathode may be formed from any suitable material that has sufficient corrosion resistance in the intended use environment to perform adequately over the anticipated lifetime. For instance, the cathode may be formed from copper, silver, gold, platinum, aluminum, or alloys thereof. Alternatively, the cathode may be made of a non-metallic conductor, such as graphite. Allowing greater material selection options for the cathode may reduce cost and improve design flexibility.
Some self-passivating metals used for electrical contacts are much more expensive than traditional metals used for electrical contacts. For instance, niobium is approximately ten times as expensive as a copper alloy such as copper-beryllium (e.g., Unified Numbering System (UNS) C17200) commonly used for contacts in electrical contacts. Use of a copper alloy for the cathode would significantly reduce the cost of the raw materials in the electrical connector. Additionally, niobium is soft and gummy to machine, whereas copper alloys can be harder materials that are easier to machine, resulting in lower manufacturing costs. Further, some self-passivating materials may have a lower electrical conductivity than traditional electrical contact materials. Forming the cathode from traditional electrical contact material, such as a copper alloy, may allow for the use of a smaller contact than if that contact were made from a self-passivating material, such as niobium, further reducing the cost of the overall electrical connector.
Referring now to
A power source 150 applies a voltage to the contacts 130, 140 of the electrical connector 110, and may supply power to a load that is connected through the electrical connector 110. The power source 150 includes a positive terminal 160 connected to the anode 130 and a negative terminal 170 connected to the cathode 140. In one example, the power source 150 provides a static voltage difference between the positive terminal 160 and the negative terminal 170. Alternatively, the voltage difference between the positive terminal 160 and the negative terminal 170 may vary with time, for instance, to convey information through the electrical connector 110. Examples of other power sources suitable for use with the contacts described herein are shown and/or described in U.S. patent application Ser. No. 16/200,147, filed on Nov. 26, 2018, the disclosure of which is incorporated by reference herein.
The electrical connector 110 is shown in
Referring now to
When the electrical connector 110 is connected to a power source (e.g., power source 150) as described above and exposed to the adverse environment 210, the anode 130, which includes at least an outer cladding of self-passivating material 132, reacts with the environment 210 to form a passivation layer 220. The cathode 140, which is formed from non-passivating material 142 does not react with the environment 210. The passivation layer 220 is electrically insulating and prevents the voltage applied by the power source 150 from pushing current through the environment 210. In one example, the passivation layer 220 may be an oxide or other compound formed from the self-passivating material 132. For instance, the self-passivating metal 132 may be niobium metal and the passivation layer 220 may be an oxide of niobium, such as Nb2O5. Referring now to
The electrical connector also includes a negative electrode 340 formed from a non-passivating material 342. The negative electrode 340 is configured to match the negative cathode 140 of the electrical connector 110. In one example, the non-passivating material 342 is the same material as the non-passivating material 142 to reduce galvanic corrosion between dissimilar metals. Dissimilar metals may also be used for materials 342 and 142 to reduce galling that can occur between similar metals when in sliding contact. Similar to the positive anode 130 and the negative cathode 140 described with respect to
The electrical connector 310 is shown connected to a load 350, with the positive electrode 330 being connected to a first terminal 352 and the negative electrode 340 being connected to a second terminal 354. The load 350 may include one or more electrical circuits configured to receive power and/or communication signals via the electrical connector 310.
In one example, the action of mating the electrical connector 110 with the electrical connector 310 acts to physically scrape the passivation layers 220 and 334 from the electrodes 130 and 330, respectively, to bring the electrodes into good electrical contact with each other. During the processing of connecting the two electrical connectors, the adverse environment 210 may be expelled from the shrinking space between the respective electrodes and between the respective connector bodies through vent holes (not shown). However, there is no need to exclude the adverse environment 210 as long as the form of the connector bodies and/or electrodes allow for sufficient electrical contact between the respective electrodes.
Referring now to
The negative terminal of the battery 420 is connected to a seawater ground electrode 440 that extends from the UUV 410 into the electrically conductive environment 210. The electrically conductive environment 210 allows current to flow through the conductive environment 210 from the seawater ground electrode 440 to a complementary seawater ground electrode 445 that is connected to the negative terminal of the power source 425 as an electrical return. The seawater ground electrode 440 and the complementary seawater ground electrode 445 may be made from corrosion-resistant material, such as graphite, mixed metal oxides, or noble metals.
In the example shown in
Referring now to
At 520, a self-passivating anode contact is formed from an electrically conducting material that forms a passivation layer when exposed to an expected use environment. In one example, the self-passivating material may be a transition metal, such as niobium or titanium, which forms an electrically insulating oxide or other compound when exposed to water. In another example, the self-passivating electrically conductive material is plated on a different electrically conductive material, which may be less expensive or easier to manufacture. In yet another example, the self-passivating anode contact may be formed as a pin, plate, hole, slot, protrusion or receptacle.
At 530, a non-passivating cathode contact is formed from an electrically conductive material that is unreactive to the environment in which the electrical connector is expected to be used. In one example, the electrically conductive material of the non-passivating cathode contact may be copper or a copper alloy, which is inexpensive and simpler to machine than the electrically conductive material of the self-passivating anode contact. In another example, the non-passivating cathode contact may be formed as a pin, plate, hole, slot, protrusion, or receptacle.
In one example, the manufacturing technique for forming the self-passivating anode may differ from the manufacturing technique for forming the non-passivating cathode, for example, due to the differing materials. For instance, niobium is relatively soft, which presents challenges to machining, but may be easily cut with an electric discharge machine. Additionally, niobium presents significant obstacles to chemical etching, but copper may be easily etched to form a contact.
At 540, the self-passivating anode contact and the non-passivating cathode contact are installed in the connector body to form the electrical connector. The anode/cathode contacts may be formed separately from the connector body and joined to the connector body, e.g., by being press fit into the body. Alternatively, the anode/cathode contacts may be formed within the connector body.
In summary, the techniques described herein provide for the use of a self-passivating material for only the anodic (positive) contact of an electrical connector for use in adverse, e.g., underwater, environments. Enabling one of the two contacts in the electrical connector to be made from a self-passivating metal while the other contact is made from any corrosion-resistant electrical conductor lowers the cost and opens the design space for underwater electrical connectors.
Methods and systems are disclosed herein with the aid of functional building blocks illustrating functions, features, and relationships thereof. At least some of the boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries may be defined so long as the specified functions and relationships thereof are appropriately performed. While various embodiments are disclosed herein, it should be understood that they are presented as examples. The scope of the claims should not be limited by any of the example embodiments disclosed herein.
What has been described above are examples. It is, of course, not possible to describe every conceivable combination of components or methodologies, but one of ordinary skill in the art will recognize that many further combinations and permutations are possible. Accordingly, the disclosure is intended to embrace all such alterations, modifications, and variations that fall within the scope of this application, including the appended claims. As used herein, the term “includes” means includes but not limited to, the term “including” means including but not limited to. The term “based on” means based at least in part on. Additionally, where the disclosure or claims recite “a,” “an,” “a first,” or “another” element, or the equivalent thereof, it should be interpreted to include one or more than one such element, neither requiring nor excluding two or more such elements.
