Patent Publication Number: US-9893460-B2

Title: Underwater electrical contact mating system

Description:
TECHNICAL FIELD 
     This disclosure relates to electrical connectors, and more particularly to a system and method to provide underwater electrical mating connections utilizing self-passivating transition metals. 
     BACKGROUND 
     To avoid water contamination of electrical contacts, conventional receptacle and female plug electrical connectors may be sealed by o-rings or gaskets. These designs may work well in generally dry environments however electrical connectors in some applications may be exposed to non-dry air environments, such as humid air, rain, or seawater. Further still, a connector may be submerged in water, for example, ships, submarines, or underwater equipment, for example. Thus, it may be desirable to exclude water from the electrically live portions of the connectors as, among other things, water may create electricity leakage paths. Water can damage the electrically conducting connector contacts by corrosion or by deposition of insulating salts or impurities onto the connectors. In certain applications and environments, it is desirable to not only exclude water after being mated, but also to exclude water during mating—even when mating under water. 
     Conventional connectors addressing underwater mating or mating in a wet environment may be complex. Such connectors may be filled with oil and may have many small parts, such as dynamic seals and springs, for example. Due, at least in part, to their complexity, conventional connectors may be difficult to build and repair. Such connectors may also be expensive to produce and replace. Dielectric gel containing connectors can also be designed to allow underwater mating of connectors with water exclusion, for example. However, repeated connection and disconnection of these gel-containing connectors may lead to contamination, leakage of the gel, or other problems. 
     SUMMARY 
     This disclosure relates to a system and method to provide underwater electrical mating connections utilizing self-passivating transition metals. In one aspect, a system includes a first mating component formed from a self-passivating transition metal to supply power. The self-passivating transition metal has a property of forming a non-conductive passivation layer when immersed in water. A second mating component formed from a self-passivating transition metal provides a return path for the power and prevents a leakage path from forming due to the formation of the non-conductive passivation layer when the power is applied to the first mating component in the water. 
     In another aspect, a system includes a first mating pin formed from a self-passivating transition metal to supply power. The self-passivating transition metal has a property of forming a non-conductive passivation layer upon immersion in water. A first mating receptor is formed from a self-passivating transition metal to receive power from the first mating pin in the water. A portion of the non-conductive passivation layer is removed upon mating the first mating pin to the first mating receptor. A communication source communicates data across a conductive connection formed by mating the first mating pin and the first mating receptor. 
     In yet another aspect, an underwater system includes a first mating pin formed from a self-passivating transition metal to supply power. The self-passivating transition metal has a property of forming a non-conductive passivation layer upon immersion in water. A second mating pin is formed from a self-passivating transition metal to provide a return path for the power and to supply a leakage path to form the non-conductive passivation layer when the power is applied to the first mating pin in the water. A first mating receptor is formed from a self-passivating transition metal to receive power from the first mating pin in the water. A portion of the non-conductive passivation layer is removed upon mating of the first mating pin and the first mating receptor to form a conductive connection. A second mating receptor is formed from a self-passivating transition metal to receive the return path for the power from the second mating pin. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example of a system to enable mating and un-mating of exposed electrical connections in an underwater environment. 
         FIG. 2  illustrates an example of forming an electrical contact of exposed electrical connections in an underwater environment. 
         FIGS. 3A-3C  illustrates example connector configurations. 
         FIG. 4  illustrates examples of self-passivating transition metals that can be utilized for connector pins or receptors. 
         FIG. 5  illustrates an example of system to communicate data via direct current power in an underwater environment. 
         FIG. 6  illustrates an example of system to communicate data via alternating current power in an underwater environment. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to a system to provide underwater electrical mating connections utilizing self-passivating transition metals. A self-insulating underwater electrical connector (SUEC), in one example, is provided for direct current (DC) power transfers and data exchanges (e.g., between devices, systems, a pair of electrical conductors, and so forth). The SUEC includes connector pins and a socket interface configured with mating receptors for accepting the connector pins, or any pair of contacting surfaces including flat plates. The mating receptors and the connector pins can be fabricated out of self-passivating transition metals such as niobium (Nb) or Tantalum (Ta) metal, for example. Due to the electrochemical properties of the transition metals, a passivation layer can be formed when they are exposed to water. Thus, when the mating receptors and/or the connector pins interact with water, a non-conductive passivation layer forms on a surface of the connector pins and/or the receiving ports to provide insulation from the water. 
     The connector pins can be mated with the mating receptors by positioning (configuring) each connector pin or surface with a respective receptor. The positioning of the connector pins within the mating receptor causes each connector pin to contact a physical port. Since the receptor and the connector pin are fabricated out of transition metals, the physical contact causes a disruption in their respective passivation layers to form a low resistance connection. The low resistance connection provides an electrical connection (electrical medium) through which power and/or data can be exchanged. The connector pin can also be un-mated (disconnected) from the receptor of the SUEC. Disconnecting the connector pin from the receptor exposes the connector pin and the receiving port to the water. This exposure causes the connector pin and the receiving port to re-grow the passivation layer to provide the insulation from the water, and thus, prevent current leakage from the exposed contacts into the water. 
       FIG. 1  illustrates an example of a system  100  to enable mating and un-mating of exposed electrical connections in an underwater environment. The system  100  includes a first housing (H 1 ) (also referred to as socket interface) that includes a first mating component (P 1 ) formed from a self-passivating transition metal to supply power from a power source  110  (e.g., AC or DC power supply). The self-passivating transition metal has a property of forming a non-conductive passivation layer when immersed in water  120 . As used herein, the term component can refer to a mating pin or a mating receptor or any mating surface in a given connector housing or socket interface. A second mating component (P 2 ) formed from the self-passivating transition metal provides a return path for the power  110  and prevents formation of a leakage path for (IL) by forming the non-conductive passivation layer when immersed in the water  120 . After the passivation layer has formed, the leakage current IL substantially reduces toward zero current. Although the first and second mating components P 1  and P 2  are shown as pins (e.g., male type pins) in this example, P 1  and/or P 2  could be implemented as receptors (e.g., female type sockets) in other examples as illustrated and described below with respect to  FIGS. 3A-3C  or as plates, for example. 
     The system  100  includes a second housing connector (H 2 ) that includes at least two mating components shown as receptors R 1  and R 2  in this example to form a load circuit to a load  130  via the first mating component P 1  and the second mating component P 2  of the first housing connector H 1 . As will be illustrated and described below with respect to  FIG. 2 , a portion of the non-conductive passivation layer of at least one mating component is removed by contact to form a conductive connection when the first housing connector is connected to the second housing connector in the water  120 . Although not shown, when immersed in water passivation layers can also form on P 2 , R 1 , and R 2 . If a disconnection occurs between H 1  and H 2 , the passivation layer reforms over P 1 . The self-passivating transition metal forming pins P 1  and P 2  and receptors R 1  and R 2  can include at least one of niobium, tantalum, titanium, zirconium, molybdenum, ruthenium, rhodium, palladium, hafnium, tungsten, rhenium, osmium, and iridium, for example. A communication source (See e.g.,  FIG. 5 ) can be provided communicate data across the conductive connection formed when the first housing connector H 1  is connected to the second housing connector H 2 . The communication source can be a radio frequency modulator, for example, that communicates data across the conductive connection via modulation of DC current flowing in the conductive connection. 
     In one specific example, the system  100  provides a self-insulating underwater electrical connector (SUEC) for alternating current (AC) or direct current (DC) power transfers and data exchanges (e.g., between devices, systems, a pair of electrical conductors, and so forth). The SUEC includes connector pins P 1  and P 2  and a socket interface configured with mating receptors R 1  and R 2  for accepting the connector pins. The mating receptors and the connector pins can be fabricated out of self-passivating transition metals such as niobium (Nb) or Tantalum (Ta) metal, for example. Due to the physical properties of the transition metals, a passivation layer can be formed when the transition metals are exposed to water  120 . As used herein the term water can include any type of water (e.g., salt water, well water, lake water, river water) that includes enough mineral content to support leakage current flows such as IL described herein. When the mating receptors R 1  and R 2  and/or the connector pins P 1  or P 2  interact with water  120 , a non-conductive passivation layer forms on a surface of the connector pins and/or the receiving ports by providing insulation from the water. 
     The connector pins P 1  and P 2  can be mated with the mating receptors R 1  and R 2  by positioning (configuring) each connector pin with a respective receptor. The positioning of the connector pins within the mating receptor causes each connector pin to be within physical contact with a physical port. Since the receptor and the connector pin are fabricated out of transition metals, the physical contact causes a disruption in their respective passivation layers to form a low resistance connection. The low resistance connection provides an electrical connection (electrical medium) through which power and/or data can be exchanged. The connector pins P 1  and P 2  can also be un-mated (disconnected) from the receptor of the SUEC. Disconnecting the connector pin from the receptor exposes the connector pin and the receiving port to the water. This exposure causes the connector pin and the receiving port to re-grow the passivation layer to provide the insulation from the water, and thus, prevent current leakage from the exposed contacts into the water. 
       FIG. 2  illustrates an example of forming an electrical contact of exposed electrical connections in an underwater environment. A connector  200  is formed from a first housing  210  having pin P 1  and second housing  220  having receptor R 1  shown as a dotted line. As P 1  engages R 1 , portions of a passivation layer  230  are removed or scraped away via contact between pin and receptor. Example contact locations are shown at  240  and  250  where the passivation layer  230  has been removed due to contact. In another example, P 1  and R 1  can be plates rather than pins that contact each other when the first housing  210  is placed in contact with the second housing  220 . 
     In one specific example, contacts for both the male pins P 1  and female receptors R 1  can be made out of a transition metal such as niobium metal, for example. Niobium is a transition metal and is in the same group as tantalum in the periodic table, for example. Using oxide growth principles connector  200  grows the passivation layer  230  on its contacts P 1  and R 1  which provides a durable insulating layer which prevents the flow of electricity through water after contact is made. When a mating contact also made of niobium (or other transition metal) interfaces with the connector  200 , it locally disrupts the passivation layer  230  on the pin and receptor and allows for a low resistance connection between the two while still preventing short circuiting through the water to the complementary electrode. The connector  200  effectively “grows” its own insulation in any area of the connector which is exposed to water. Rather than trying to rely on complex seals and oil to exclude water as in a conventional wet-mate connector, the connector  200  utilizes water being in contact with the contacts P 1  and R 2  to form the insulation. 
     In one specific example of forming the passivation layer  230 , 50VDC (or other potential) can be applied to contacts in the housing  210  and/or  220  before and after immersion in sea water, for example. The contacts can be separated by about 50 mm where all metal surfaces of the contacts exposed to the water are a transition metal such as niobium metal. When power is applied, initial leakage current (IL) through the water with the exposed metal contacts is about 5 mA and rapidly decreases after the passivation layer  230  is formed. If this were a common electrode material such as copper, there would be a short circuit through the water causing rapid corrosion of the metal and generation of hydrogen and chlorine gasses. In this example, a drop of about 180 mV may be measured across both contacts and the wiring to the connectors indicating a resistance of less than 1 ohm through the wiring and contacts. This can be improved by tailoring the contact pressure and pin/socket interface to enhance conductivity when P 1  and R 1  are mated. 
       FIGS. 3A-3C  illustrate example connector configurations.  FIG. 3A  illustrates an alternative housing configuration from that depicted in  FIG. 1  where a housing  310  includes receptors R 1  and R 2  that are coupled to power source  320 . In  FIG. 3B , a housing  330  includes a mixed configuration coupled to power source  340  where at least one component of the housing includes a pin such as P 1  and at least one component of the housing includes a receptor such as R 2 .  FIG. 3C  illustrates example housings  350  and  360  where additional pins and receptors (e.g., more than two) are provided than are depicted in previous examples. 
       FIG. 4  illustrates examples of self-passivating transition metals that can be utilized for connector pins or receptors. As shown, a connector pin  410  and connector receptor  420  can include various transition metal examples that provide the capability to form insulating passivation layers when such contacts receive an applied DC voltage in water. As note previously, the self-passivating transition metals can include at least one of niobium, tantalum, titanium, zirconium, molybdenum, ruthenium, rhodium, palladium, hafnium, tungsten, rhenium, osmium, and iridium, for example. 
       FIG. 5  illustrates an example of system  500  to communicate data via direct current power in an underwater environment. The system  500  includes a first mating pin  500  formed from a self-passivating transition metal to supply power from power and communications source  510 . The self-passivating transition metal has the property of forming a non-conductive passivation layer when immersed in water. A first mating receptor R 1  is also formed from the self-passivating transition metal to receive power from the first mating pin P 1  in the water  520 . A portion of the non-conductive passivation layer is removed by contact to form a conductive connection when the first mating pin P 1  is connected to the first mating receptor R 1 . Pin P 2  and receptor R 2  are provided in housings H 1  and H 2  to provide a return path. A communication source can be provided to communicate data across the conductive connection formed by the first mating pin P 1  and the first mating receptor R 1  to a receiver  530 . In one example, the communication source can be integrated with the power source  510  as shown. In an alternative example, the communication source could be integrated within one or both of the housings H 1  or H 2 , for example. The communication source can be a radio frequency modulator, for example, that communicates data across the conductive connection via modulation of direct current (DC) flowing in the conductive connection. 
     A COM SIGNAL employed for communications is shown riding on top of a DC voltage. Thus, in addition to being able to efficiently transfer power, the system  500  can be used for high speed data transfer by superimposing a low level RF signal on top of the voltage used to provide power to the receiver  530 . This can include RF data transfer techniques such as 802.11, for example, that can be used with the system  500 . This allows a two contact connector (or more contacts (See e.g.,  FIGS. 3A-3C ) based on the passivation forming capability of the transition metal to provide both power transfer and data transfer. Niobium, for example, can be employed as a transition metal that is readily available, non-toxic, easy to work with and relatively inexpensive. These material properties and its unique electrochemical properties allow manufacturing of reliable and inexpensive wet-mate electrical connectors which can have thousands of mating cycles, for example. 
       FIG. 6  illustrates an example of system to communicate data via alternating current power in an underwater environment. Similar to the system  500  described above, the system  600  includes a first mating pin  600  formed from a self-passivating transition metal to supply power from power and communications source  610 . The self-passivating transition metal has the property of forming a non-conductive passivation layer when immersed in water. A first mating receptor R 1  is also formed from the self-passivating transition metal to receive power from the first mating pin P 1  in the water  620 . A portion of the non-conductive passivation layer is removed by contact to form a conductive connection when the first mating pin P 1  is connected to the first mating receptor R 1 . Pin P 2  and receptor R 2  are provided in housings H 1  and H 2  to provide a return path. A communication source can be provided to communicate data across the conductive connection formed by the first mating pin P 1  and the first mating receptor R 1  to a receiver  630 . In one example, the communication source can be integrated with the power source  610  as shown. In an alternative example, the communication source could be integrated within one or both of the housings H 1  or H 2 , for example. The communication source can be a radio frequency modulator, for example, that communicates data across the conductive connection via modulation of alternating current (AC) flowing in the conductive connection. 
     A COM SIGNAL employed for communications is shown riding on top of an AC voltage. Thus, in addition to being able to efficiently transfer power, the system  600  can be used for high speed data transfer by superimposing a low level RF signal on top of the voltage used to provide power to the receiver  630 . This can include RF data transfer techniques such as 802.11, for example, that can be used with the system  500 . This allows a two contact connector (or more contacts (See e.g.,  FIGS. 3A-3C ) based on the passivation forming capability of the transition metal to provide both power transfer and data transfer. 
     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.