Abstract:
A strain relief, modular, self-aligning, corrosion resistant, highly conductive, environmentally sealing cable clamp or “backshell” has a female adapter having a coupling ring at its proximal end which is connected to a rotatable flexible tubing with a split saddle clamp at is distal end and a male adapter which can be a ground or EMI/RFI adapter. This cable clamp, or “backshell”, ensures full engagement on the interfacing accessory teeth, “backshell” and connector, and resistive to environmental hazards, maintains electrical/electronic shielding integrity, improve mechanical reliability and provides form factor capability.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to the field of connection devices for electrical shielded cables and the like. In particular, it relates to a modular, self-aligning, corrosion resistant, highly conductive strain relief cable clamp sometimes referred to as a “backshell”.  
         BACKGROUND OF THE INVENTION  
         [0002]    The invention pertains to a cable clamp that combines performance, user-friendly assembly and installation, standardization and reusability. There are several important considerations in the designing of such a cable clamp. First, the “backshell” can be used as a strain relief device (providing mechanical support) and/or as an EMI/RFI grounding device (providing electrical connection) or both in the assembly of electrical shielded cable. Second, the performance attributes of a cable clamp such as its coupling mechanism, corrosion resistivity, conductivity properties and usage application should preferably be maximized at least to some extent while the related assembly tools and operator skill/learning attributes should be minimized at least to some extent. Another desirable feature would be the provision of an environmental sealing capability which would prevent ingress of contaminants, fluid or grime or otherwise, onto the electrical connector. In particular, cable clamps installed in applications such as aircraft my be subject to fluids such as fuel, cleaning fluid, lubricating fluid, deicing fluid, hydraulic fluid, water and other substances not desired to contact electrical connections.  
           [0003]    While prior art cable clamp mechanisms have been industry accepted, several deficiencies and disadvantages exist. For example, ground shield termination using lugs and a commonly accepted method called “banding” to terminate electrical cable individual and overall shields requires laborious, error-prone, non-reusable assembly. Another is the plating finish used to protect the “backshell” from corrosion inducing contaminant such as hydraulic, aviation, de-icing fluids, and other contaminants while retaining its electrical conductivity requirement. Also, the cost associated with customized cable clamps, to be either straight or angular due to its installation usage, can be significant.  
           [0004]    Previous designs can also be somewhat complicated at the point of assembly, where multiple cables need to be grounded. Care must be taken to properly connect each cable and to ensure a proper electrical connection. Accordingly, a cable clamp that is easily connected to cables through standard electrical connections such as pigtail connections is desired.  
           [0005]    Some known designs may further not lend themselves to maintenance by being disassembled and then reassembled. Many known designs, in fact, are meant to be assembled only once and must be replaced if they are opened for maintenance. Accordingly, a cable clamp which lends is self to assembly and disassembly for maintenance and repair is desired.  
           [0006]    Other disadvantages with known clamp designs include a reduced ability to seal the electrical connector from foreign substances. Accordingly, it is desirable to provide a clamp that provides a sealing member to the electrical connector from foreign substances.  
           [0007]    It would also be desirable to use a similar “backshell” male member, split compression ring and a wrap-around band as described, in U.S. Pat. No. 6,406,329.  
           [0008]    Thus, it would be desirable to have a cable clamp whose attributes and functionality are designed to enhance efficiency with regard to its coupling methodology, corrosion resistivity, conductivity, assembly, usage, sealing protection, tooling, installation and reusuability.  
         SUMMARY OF THE INVENTION  
         [0009]    In one aspect, the invention provides an electrical connector strain relief cable clamp which has desirable characteristics in its coupling methodology, corrosion resistivity, conductivity, assembly, usage, sealing protection, tooling, installation and reusability. The clamp is modularly constructed, is self-aligning, has selective finishes and environmental sealing protection. The cable clamp has a female adapter with a threaded, self-seating or self-locking coupling ring at its proximal end connected to a rotatable, temperature flexible tubing having a split saddle clamp at its distal end, and a male adapter with a conductive finish. The male adapter can be a ground adapter having accessory teeth on its proximal end and with a plurality of electrical contact retention clips embedded around the peripheral area of its termination platform; and assembled onto it is a corrosion resistant seal compression ring strategically placed forward of its accessory teeth. Alternatively the male adapter can be an EMI/RFI adapter having accessory teeth on its proximal end and a pre-spaced slotted distal end around its periphery. Assembled onto the adapter is a corrosion resistant seal compression ring strategically placed forward of its accessory teeth. Included to be used with the EMI/RFI adapter are a split compression ring and a wrap-around band as described in U.S. Pat. No. 6,406,329.  
           [0010]    It is another feature of the invention to provide a strain relief cable clamp that in some embodiments takes advantage of the properties, improvements and novelties described in U.S. Pat. No. 6,406,329.  
           [0011]    A further feature of the invention is to enable a standard strain relief cable clamp where the form factor or routing installation, either straight or angular, is met.  
           [0012]    A still further feature of the invention is providing a strain relief cable clamp with selective finish or plating where both corrosion resistant and electrically conductive properties are achieved without compromising one or the other.  
           [0013]    It is also a feature and advantage of the present invention to provide a clamp that provides a sealing member to the electrical connector from foreign substances. It is another feature and advantage of the present invention to provide a clamp that is reusable and capable of being opened for maintenance or other working and then resealed. It is another feature and advantage of the present invention to provide a clamp with a flexible tubing attached, therefore enabling the clamp to be used in different environments where either a straight, curved, or angular clamp is required.  
           [0014]    The above and other features and advantages are achieved through the use of a novel method for clamping wires and a clamp as herein disclosed. In one further aspect the invention provides a cable clamp comprising: a first corrosion resistant backshell member, and a second electrically conductive backshell member configured to accommodate at least one of a wire end and a cable termination end to provide grounding, wherein said first and second backshell members attach to each other and said first backshell member substantially contains said second backshell member when said backshell members are connected to the electrical connector.  
           [0015]    In another further aspect, the invention provides a cable clamp comprising: electrically conductive means for grounding at least one of a wire end and a cable termination end to provide grounding, and corrosion resistant means for surrounding the grounding means, wherein said surrounding means attached to said grounding means and provides substantial corrosion protection to said grounding means when the clamp is connected to the electrical connector.  
           [0016]    In accordance with another aspect of the present invention, a method of grounding an electrical system is provided. The method comprises: engaging a first backshell member to an electrical connector via teeth located on the first backshell member and the connector, grounding at least one of a shield cable to the first backshell member, covering the first backshell member with a second backshell member, and attaching the second backshell member to the electrical connector and fully shielding the first backshell member within a space defined, at least in part, by the second backshell member and the electrical connector.  
           [0017]    There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.  
           [0018]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.  
           [0019]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is an exploded perspective view of one embodiment of the present invention, illustrating a strain relief cable clamp or “backshell” having a female adapter with a coupling ring on its proximal end connected to a flexible tubing and a first type of male adapter with accessory teeth in the form of a ground adapter having a plurality of electrical contact retention clips embedded around the peripheral area of its termination area and a corrosion resistant seal compression ring, where the tubing portion of the female adapter is in a straight position.  
         [0021]    [0021]FIG. 2 is an exploded perspective view of one embodiment of the present invention similar to FIG. 1, but where the male adapter is an EMI/RFI adapter having a slotted distal end and a wrap-around band and split compression ring.  
         [0022]    [0022]FIG. 3 is an exploded perspective view of the embodiment of FIG. 1, where the tubing portion of the female adapter is in a bent position and showing the wire and/or cable shield termination.  
         [0023]    [0023]FIG. 4 is an exploded perspective view of the embodiment of FIG. 2, where the tubing portion of the female adapter is in a bent position and showing the wire and/or able shield termination.  
         [0024]    [0024]FIG. 5 is a cut away side sectional view of an embodiment of the invention with an electrical connector being coupled to the present invention strain relief cable clamp, illustrating the seal compression ring forming a seal around the cavity of the connector grommet and shell.  
         [0025]    [0025]FIG. 6 is a cut away side elevation view of an embodiment of the present invention, with the backshell assembled onto the electrical connector, a portion thereof being broken away to show the electrical junction formed by the interfitting metallic shell, housing and coupling parts all joined together with the terminated overall ground shields shown. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    A preferred embodiment of the present invention in the form of a cable clamp, sometimes referred to as a “backshell”, is shown in FIGS.  1 - 6 , wherein like reference numerals indicate like elements. The cable clamp described herein is in some aspects similar to the cable clamp described in U.S. Pat. No. 6,406,329 which is hereby incorporated herein by reference in its entirety.  
         [0027]    This strain relief cable clamp is modular in construction and comprises a female adapter  1  and a male adapter  2  or  2 A. The females adapter  1  has a (having a coupling ring  3  with a self-seating or self-locking anti-coupling device (not shown) such as is known in the prior art) connected to a rotatable, graded temperature flexible tubing  4  attached to a split saddle clamp  5  at its distal end. The saddle clamp  5  uses hex-head screws  6  and clinch nuts  7  for ease of assembly. In the embodiment of the invention shown in FIG. 1, the flexible tubing  4  is shown in a straight position, however, the tubing  4  may be configured in a multitude of positions to accommodate installation of the clamp in a variety of locations. Examples of different tubing positions are shown in FIGS. 2 and 4.  
         [0028]    The other main component of the exemplary “backshell” is a male adapter  2  or  2 A in the form of either a ground adapter  2  as seen in FIGS. 1 and 3 or an EMI/RFI adapter  2 A as seen in FIGS. 2 and 4. The adapter  2  or  2 A has accessory teeth  8 , a seal compression ring  9  and an electrically conductive finish such as by plating. The functionality of the cable, such as an airplane system requirement, circuit grounding and/or noise filtering determines the selection of the type of male adapter  2  or  2 A.  
         [0029]    To better understand the overall assembly, the assembly of this strain relief cable clamp can be simply described as the female adapter  1  engaging the male adapter  2  or  2 A under compressive load. The coupling ring  3  on the female adapter  1  is coated with a corrosion resistant finish such as black anodized. The female adapter  1  has a different finish than the male adapter  2  or  2 A. Having such selective finishes provides the ability to withstand harsh environmental condition and associated fluids such as hydraulic, lubricating, fuel, anti-deicing, cleaning, and the like, while retaining the backshell&#39;s desirable conductivity property.  
         [0030]    The coupling ring  3  of the female adapter  1  shields the male adapter  2  or  2 A from any outside exposure as shown in FIGS. 5 and 6. Having these selective finishes enables the desirable capabilities of high corrosion resistivity and conductivity. Some embodiments also have a seal compression ring  9 , shown in FIG. 5 whose function is to wedge into the cavity between connector grommet  10  and shell  11  thereby preventing any ingress of contaminant, fluid, grime or combination therefore, which degrade the bond  12  on the grommet  10  and shell  11 , creating a path that causes electrical arcing or shorts. The seal compression ring  9  has a corrosion resistant finish.  
         [0031]    As described above, the present invention uses either of two types of males adapters. A first type of adapter is a ground adapter  2  that uses the conventional shield pigtail lug termination. It also uses a standard M39029/58 size 22 pin contact  13  installed or inserted in a retention clip  14 . There is an array of retention clips  14  embedded around the peripheral area of the adapter termination area  15 . Also, included is the seal compression ring  9  as described above. The second type of male adapter is an EMI/RFI adapter  2 A used in the individual and/or overall wire and cable shield termination. The male adapter  2 A is similar to the adapter described in U.S. Pat. No. 6,406,329 and its usage with a split compression ring  16  and wrap around band  17  is as described in that patent. The assembly of the present invention eliminates the prior art self seating or self-locking problematic blind coupling which results from non-engagement on the interface accessory teeth  8  and  8 A. That is, engagement or non-engagement of the accessory teeth  8  and  8 A between the backshell and the electrical connector  19  is a by product of the anti-coupling device in the coupling ring  3 . It is understood that during coupling when accessory teeth  8  and  8 A are at a peak-to-peak condition then it will cause “binding”, creating a scenario of a false coupling of the backshell and connector  19 . A prior art solution to this problem is to look through an inspection hole in the backshell and then rock the backshell back and forth to dislodge the accessory teeth  8  and  8 A from the peak-to-peak condition. This process might be repeated several times until accessory teeth  8  and  8 A are fully engaged. This process is sometimes laborious, tedius and failure prone. In some exemplary embodiments of the invention, the male adapter  2  or  2 A is simply dropped into position, meaning, the accessory teeth  8  and  8 A are fully engaged prior to the coupling ring  3  of female adapter  1  being threadedly coupled to the connector  19 . This assembly assures full engagement between the accessory teeth  8  and  8 A.  
         [0032]    As shown in FIGS. 1 and 3, the wire and cable shield  20  terminated onto the ground adapter  2  is inserted and can be removed when necessary, which provides the inventive backshell easy assembly and repairability/retrievability, compared to prior art shield pigtail termination using lugs (not shown) which is not amenable to repair or retermination without replacement of the shield pigtails. Also, in the prior art, rework on the connector  19  involves laborious disassembly of the shield pigtails from the backshell saddle clamp  5 .  
         [0033]    [0033]FIGS. 2 and 4 illustrate an exemplary embodiment having the EMI/RFI adapter  20 A, which is further described in U.S. Pat. No. 6,406,329.  
         [0034]    As will now be apparent, when the female adapter  1  and electrical connector  19  are connected, the engaging ends  21  on the male adapter  2  or  2 A will be under compressive force from the tapered inner periphery or shoulder  22  located behind the internal thread  23  on the female adapter  1 . This condition forms a joint between the wire and cable shield  20  and the connector  19 . Also in place is the seal compression ring  9 .  
         [0035]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.