Abstract:
The specification discloses a cap for sealing the terminal end of a power cord, such as a marine power cord, against dirt and moisture. The specification also discloses that the cap actively prevents corrosion of the electrical contacts covered by the cap by the inclusion of corrosion-inhibiting compounds dispersed within the plastic of the cap. The corrosion-inhibiting compound are released in gaseous form within the cap, thereby inhibiting corrosion of the electrical contacts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The preferred embodiments of the present invention relate generally to electrical power cords. More particularly, the preferred embodiments relate to a sealing cap for the end of an electrical power cord. More particularly still, the preferred embodiments relate to a moisture-resistant corrosion-inhibiting threaded sealing cap for use with an onshore power cord in marine applications. 
     2. Background of the Invention 
     When docked, a marine vessel generally requires a source of electricity other than its own batteries in order to enable operation of electrical appliances onboard without depleting the batteries. Electrical power is typically provided from an onshore power supply to a receptacle on the boat via a marine power cord. However, marine power cords are prone to wetness and resultant corrosion due to the risk of precipitation and proximity to water. 
     Preventing moisture from contacting the electrical connections, including the receptacles and terminal end of the power cord, is of utmost importance. Salt water is especially damaging to electrical connections, as dissolved salt increases the conductivity of the aqueous solution formed at the surface of a metal and enhances the rate of electrochemical corrosion. In addition, using a wet power cord is dangerous due to the risk of electrical shock or shorting. If moisture were to enter the connection when electricity is flowing, the connection could short out, potentially tripping the breaker of the onshore power supply. 
     Many boaters cover the ends of marine power cords by placing a plastic bag over the terminal end and securing the end of the bag to the cord with a rubber band or twist tie. Although this method largely prevents moisture intrusion, a bag is not always handy and is not quickly and easily installed and removed. In addition, this method does nothing to prevent corrosion due to humidity build-up or small amounts of moisture. Moreover, this method does not structurally protect the terminal end from mechanical damage, such as being stepped on or crushed by equipment, which could occur if left unprotected. 
     There have been attempts in the related art to slow corrosion in electrical connectors. For example, U.S. Pat. No. 3,372,361 to Wengen appears to disclose the use of a corrosion inhibitor in gel form within a cavity where two dissimilar metals meet. Likewise, U.S. Pat. No. 5,844,021 to Koblitz discloses a corrosion inhibitor in a gel form in the Koblitz connectors. Each of Wengen and Koblitz may be characterized in that the corrosion inhibitor must be in contact with the conductors where the anti-corrosion properties are desired. U.S. Pat. No. 6,300,574 to Franey discloses an electrical cap that contains sacrificial metals with which corrosives react, thus protecting to some extent remaining electrical components within the cap. 
     The Wengen and Koblitz techniques, utilizing a gel, are simply not suitable for use in marine power cord and related applications. The Franey technique of placing sacrificial metals within the polymer cap is only a passive technique, and thus may not provide sufficient protection in corrosive environments, such as marine applications. 
     Thus, what is needed in the art is a cap for electrical connectors, such as marine power cords, that is convenient to use, that is not easy to lose, and that more aggressively protects the electrical connectors within the power cord from corrosion. 
     BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS 
     The problems noted above are solved in large part by a cap and related method for sealing the terminal end of a marine power cord against moisture. More particularly, the preferred embodiments are directed to a cap that seals the terminal end of a marine power cord against dirt and moisture, and where the cap inhibits corrosion of the electrical connections. The preferred embodiments relate to a positively buoyant plastic cap having a threaded section for mating to a corresponding section on the terminal end of a power cord, forming a moisture-proof seal. The preferred embodiments also comprise a corrosion-inhibiting compound dispersed within the plastic material of the cap. An alternate embodiment includes a cap having a corrosion-inhibiting compound integrally dispersed within a plastic insert coupled inside the cap. The corrosion-inhibiting compound is released from the composite plastic cap, or composite plastic insert, in gaseous form actively preventing corrosion of the electrical contacts of the power cord. 
     The disclosed devices and methods comprise a combination of features and advantages which enable it to overcome the deficiencies of the prior art. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a detailed description of the preferred embodiments of the invention, reference will made to the accompanying drawings in which: 
     FIG. 1A shows an elevation view of an embodiment engaged with the terminal end of a conventional power cord; 
     FIG. 1B shows an embodiment of the present invention disengaged from the terminal end of a conventional power cord; 
     FIG. 2A shows a top view of an embodiment of the present invention; 
     FIG. 2B shows a sectional view of an embodiment of the present invention; 
     FIG. 3A shows an elevation view of an alternate embodiment engaged with the terminal end of a conventional power cord; 
     FIG. 3B shows an alternate embodiment disengaged from the terminal end of a conventional power cord; 
     FIG. 4A shows a bottom view of an alternate embodiment of the present invention; and 
     FIG. 4B sectional view of an alternate embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments are directed to a power cord sealing cap which overcomes many deficiencies of the prior art. FIGS. 1A and 1B show a first embodiment in engaged and disengaged positions, respectively, with a conventional marine power cord assembly  12 . Before proceeding, it must be understood that the preferred embodiments were developed in the context of marine power cords for transfer of power from the shore to the vessel, and therefore they will be described in that context; however, the systems and methods described find application outside the marine power cord context, and thus the description in this manner should not be construed as a limitation as to the breadth of the invention. Referring to FIG. 1A, male power cord sealing cap  10  is shown engaged with terminal end  11  of power cord  12 , which further includes cable portion  13 . The power cord has an outer protective jacket that protects a plurality of metallic conductors therein. The metallic conductors electrically couple to metallic contacts in the terminal end  11  of the power cord. When in use, terminal end  11  plugs into an onboard electrical receptacle (not shown). If left uncovered while not in use, the electrical contacts in the power cord terminal end  11  could be damaged, soiled or become wet, potentially affecting the operation of the electrical connections in the terminal end. Using a wet electrical power cord  12  is particularly dangerous, since water on the cord surface could potentially conduct current. In addition to water or other liquids that may contact the electrical connections on terminal end  11 , humidity present in the air could potentially corrode the electrical contacts even when enclosed within cap  10 . 
     Cap  10  is preferably tubular in nature, has a substantially circular cylindrical cross-section, and is made of a polymeric thermoplastic material, such as high density polyethylene (HDPE). When engaged, the cap substantially protects the power cord terminal end  11  from impact, dirt, moisture and ensuing corrosion. In addition, the cap  10  of the preferred embodiments is positively buoyant in water, with a specific gravity of less than approximately 0.98, less than that of salt or fresh water, so that it floats and is easily retrieved should it fall. 
     Referring now to FIG. 1B, cap  10  includes an externally threaded male connection  14  that engages corresponding internally threaded female connecting ring  16  on terminal end  11 , forming a substantially secure and moisture-resistant seal. In addition, unlike the sliding fits of some related art caps, the threaded connection between cap  10  and power cord  12  requires manual force in order to be disengaged. Cap  10  is preferably linked to cable portion  13  of cord  12  by a lanyard  15  comprised of any suitable material such as strong plastic, small chain and the like, thereby preventing unintentional loss. 
     FIG. 2A shows a top view of an embodiment of male power cord sealing cap  10 , which includes hole  17  for attaching the lanyard or other mechanisms that could securely linking the cap to a power cord. FIG. 2B shows a side view of cap  10  taken along line  2 — 2  of FIG.  2 A. Cap  10  includes cavity  18  in which the terminal end or connector of a power cord (not shown) is enclosed. Threads  14  are designed to engage with a typical internally threaded connecting ring  16  located on terminal end  11 , thereby forming a moisture-proof seal. 
     FIGS. 3A and 3B show an alternate embodiment in engaged and disengaged positions, respectively, with conventional power cord  22 . Referring now to FIG. 3A, female power cord sealing cap  20  is shown engaged with terminal end  21  of male power cord  22 , which further includes cable portion  23 . Cap  20  is designed to engage terminal end  21 , which has a double-lead “L”-shaped thread  30  (only one shown in FIG. 3B) which when engaged with corresponding threads in cap  20  holds the cap in place. In this alternate embodiment, sealing of the terminal end  21  takes place between shoulder  40  and a corresponding location  44  (FIG. 4B) of cap  20 . Additionally, surface  42  may form a friction-type fit with surface  46  (FIG. 4) of the cap  20 . It will be understood that, while the sealing caps of the preferred embodiments have been shown to engage typical threaded and L-lock-shaped threaded terminal ends, many variations in the thread design are possible without departing from the scope and spirit of the invention. 
     FIG. 4A shows a bottom view of the embodiment of female power cord sealing cap  20  for covering a male terminal end (not shown). FIG. 4B shows a side view of cap  10  taken along section  4 B— 4 B of FIG.  4 A. Cap  20  includes internal cavity  24  in which the terminal end of a male power cord may be enclosed. Cavity  24  typically includes a wider opening section  25  and a narrower internal section  26  having an internally threaded portion  27  for engaging an externally threaded section of a male terminal end (such as double-lead —“L”—shaped thread  30  of FIG.  3 B). 
     Since ambient humidity may become trapped inside a power cord sealing cap when engaged with the terminal end of the power cord, the moisture-resistant seal alone may not be sufficient to protect against corrosion of the electrical connections. Over time, humidity and condensation inside the cap may contribute to corrosion, thus, the preferred embodiments actively inhibit corrosion within a power cord sealing cap. 
     The preferred embodiments comprise a corrosion-inhibiting material dispersed within plastic material of the power cord sealing cap, forming a composite cap material. The material of the preferred embodiments is polyethylene integrally incorporating a plastic-additive corrosion inhibitor in solid form that is released as in gaseous form inside the cap. Any corrosion inhibitor that can be dispersed within the preferred material is suitable, such as a plastic additive marketed under the trade name M-226 MF Masterbatch by Cortec Corporation. Using the Cortec Corporation material, the additive should represent 2.5% of the volume of the cap material. In an alternative embodiment, the cap may be a homogeneous polyethylene cap that comprises a composite corrosion-inhibiting insert  8  (FIG. 2B) coupled within the cap. In this embodiment, as the corrosion-inhibiting agent is depleted, the insert  8  may be removed and replaced, thereby extending the useful life of the cap  10 . 
     The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.