Patent Publication Number: US-9419384-B1

Title: Connection system for an electrical cable

Description:
BACKGROUND 
     Electrical cables are often encased in one or more types of insulators, some of which are referred to as “shields.” For example, a cable might include an inner shield and an outer shield. Shields can serve various functions, such as reducing interference, noise, and leakage. Shields might be further encased by another layer of protection, which is sometimes referred to as a “jacket.” A backshell is often attached to an end of the cable as part of a terminus for the shields and jacket. 
     One type of shield is a “braided shield,” which includes a tubular body having a wall that is constructed of woven filaments. The filaments might include various materials, such as copper or aluminum. Braided shields provide a certain amount of optical coverage for cables. However, when a portion of the braided shield enters a backshell, the portion often begins to flare which creates gaps between the woven filaments. These gaps can reduce the amount of optical coverage and causes leakage. 
     SUMMARY 
     An embodiment of the present invention is directed to a connection system for a cable. The connection system includes a shielded cable that is inserted into a backshell. Among other elements, the shielded cable might include a ferrule that is crimped between shields near an end of the cable. In addition, the backshell includes a channel that clamps around the ferrule, as well as various solder wells. 
     Embodiments of the invention are defined by the claims below, not this summary. A high-level overview of various aspects of the invention is provided here to introduce a selection of concepts that are further described in the detailed-description section below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in isolation to determine the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated herein by reference, wherein: 
         FIG. 1  depicts a cable terminated by a backshell and connector in accordance with an embodiment of the present invention; 
         FIG. 2  depicts the cable and backshell of  FIG. 1  with part of the backshell ghosted in order to illustrate some internal configurations in accordance with an embodiment of the present invention; 
         FIG. 3  depicts an exploded view of some elements of the cable and backshell of  FIG. 1  in accordance with an embodiment of the present invention; 
         FIG. 4  depicts a partial cross section of a cable in accordance with an embodiment of the present invention; 
         FIG. 5  depicts a cross-sectional view of a cable terminated by a backshell and connector in accordance with an embodiment of the present invention; 
         FIG. 6  depicts another cross-sectional view of a cable terminated by a backshell and connector in accordance with an embodiment of the present invention; 
     
    
    
     DETAILED DESCRIPTION 
     The subject matter of embodiments of the present invention is described with specificity herein to meet statutory requirements. But the description itself is not intended to necessarily limit the scope of claims. Rather, the claimed subject matter might be embodied in other ways to include different elements or combinations of elements similar to the ones described in this document, in conjunction with other present or future technologies. Terms should not be interpreted as implying any particular order among or between various steps herein disclosed unless and except when the order of individual steps is explicitly described. 
     Generally, an embodiment of the present invention is directed to a connection system for a shielded cable. Among other elements, the shielded cable includes an inner shield and an outer braided shield. In addition, the shielded cable is terminated at a backshell. Absent the present invention, the outer braided shield might flare at the backshell, causing leaks. To reduce leakage, an aspect of the present invention includes a ferrule, which is positioned between an inner shield and the outer braided shield. In addition, an aspect includes a backshell configured with a cylindrical channel that receives a portion of the shielded cable and clamps around the braided shield, the ferrule, and the inner shield. The backshell also includes solder and epoxy wells for additional sealing. 
     Referring to  FIG. 1 , a connection system  10  is depicted in which a shielded cable  12  is terminated by a backshell  14  and a connector  16 . Generally, the shielded cable  12  is inserted into a rear portion of the backshell  14 , and the backshell is coupled to the connector  16  for connecting to other electrical components (e.g., cables, devices, etc.). 
     Referring to  FIG. 2 , the connection system  10  is depicted, and a top portion  18  of the backshell  14  is ghosted in order to illustrate some components that are obstructed from view in  FIG. 1 . For example, in  FIG. 2  the shielded cable  12  includes a cable  20 , which is encased by an inner shield  22  (e.g., foil shield). In addition, the inner shield  22  is encased by a braided outer shield  24 , which is further encased by a jacket  26 . 
     In a further embodiment, the cable assembly includes a ferrule  25  positioned between the inner shield  22  and the outer shield  24 . The ferrule  25  might be at least partially hidden underneath the outer shield  24 , such that the ferrule  25  is not viewable in  FIG. 2 . However,  FIG. 3  depicts the ferrule  25  that would be slid between the inner shield  22  and the outer shield  24  prior to attaching the backshell  14  to the cable. 
     For illustrative purposes, a partial cross section of the cable  12  is depicted in  FIG. 4 , which illustrates the layering of the components in the cable system. For instance,  FIG. 4  illustrates a set of one or more wires  20  and the inner shield  22  that at least partially encases the set of one or more wires  20 . The ferrule  25  is positioned between the inner shield  22  and the outer shield  24  and at least partially circumscribes a segment  22 B of the inner shield  22 . Accordingly, the ferrule  25  provides a full 360 degrees circumferential connection with low-impedance to the ground. 
     In a further aspect, the inner shield  22  also includes a non-circumscribed portion  22 C that is not circumscribed by the ferrule  25 . In  FIG. 4 , the outer shield  24  (e.g., braided shield) at least partially encases the ferrule  25 , and the outer shield  24  includes a portion  24 B that does not encase the ferrule  25  and that is layered directly adjacent to the non-circumscribed portion  22 C of the inner shield. The cable jacket  26  encases the outer shield  24 , which includes a terminus  24 C that extends beyond a cable-jacket terminus  26 B of the cable jacket  26 . That is, the outer shield  24  includes a non-encased portion, which at least partially overlaps with the portion  24 B that is layered directly adjacent to the inner shield. 
     Referring back to  FIG. 3 , the backshell  14  includes the top portion  18  and the bottom portion  28  that mate with one another. For instance, the top portion  18  includes fastener holes  19 A and  19 B that are aligned with fastener holes  29 A and  29 B of the bottom portion  28 . Fasteners (not shown) are secured in the aligned holes to couple the top portion  18  to the bottom portion  28 . 
     In a further aspect, a cylindrical channel is formed between the top portion  18  and the bottom portion  28  when the two portions are coupled to one another, and the cylindrical channel receives the cable  12 . For example, referring to  FIG. 2  a portion of the cable that is received between the top portion  18  and the bottom portion  28  is positioned in the cylindrical channel.  FIG. 3  more clearly shows that the bottom portion  28  includes a concave interior surface  30  that forms part of the wall of the cylindrical channel. The top portion  18  includes another concave interior surface  32  that generally opposes the bottom-portion concave interior surface  30  and that is obstructed from view in  FIG. 3  (beneath surface  34 ). 
     The concave interior surface  32  of the top portion  18  is depicted in  FIG. 6 , which shows a cross-sectional view of the backshell  14  attached to a cable  12 .  FIG. 6  also illustrates that the inner shield  22 , the ferrule  25 , and the outer shield  24  are crimped in the cylindrical channel and between the top-portion concave interior surface  32  and the bottom-portion concave interior surface  30  when the top portion  18  and the bottom portion  28  are coupled to one another. As such, the top portion  18  and the bottom portion  28  each includes respective concave interior surfaces  32  and  30  that form walls of the cylindrical channel when the portions  18  and  28  mate with one another, and the non-encased portion of the outer shield  24  (i.e., not encased by the jacket  26 ) is housed in the cylindrical channel. 
     In another aspect of the present invention, an internal groove  36  is formed between the top portion  18  and the bottom portion  28  when the two portions are coupled to one another, and the internal groove  36  is axially adjacent to the cylindrical channel. For example, referring to  FIG. 2  the internal groove  36  circumscribes a non-encased portion of the outer shield  24 .  FIG. 3  more clearly shows that the bottom portion  28  includes a concave internal groove  38  that forms part of the wall of the internal groove  36 . The top portion  18  includes another internal groove  40  that generally opposes the bottom-portion internal groove  38  and that is obstructed from view in  FIG. 3  (beneath surface  34  and depicted in  FIG. 6 ). The concave internal grooves  38  and  40  align when the backshell portions  18  and  28  are mated to form the circumscribing internal groove  36  next to the cylindrical channel. 
     The internal groove  40  of the top portion  18  is depicted in  FIG. 6 , which also illustrates that the inner shield  22 C (non-circumscribed by the ferrule  25 ) and the outer shield  24 B are circumscribed by the internal groove  36  (formed by grooves  38  and  40 ). As such, the cylindrical internal groove circumscribes the portion  24 B of the outer shield layered directly adjacent to the inner shield  24 B, when the cable is housed in the backshell. The cylindrical internal groove  36  provides a solder well for receiving a solder material  42 A and  42 B ( FIG. 6 ), which provides a seal around the portion  24 B of the braided shield. Once the cylindrical internal groove  36  is filled with solder material, the inner and outer shields are connected 360 degrees circumferentially to maintain high optical coverage of the braided outer shield  24 . 
     Referring to the various figures, the top and bottom backshell members  18  and  28  mate to form the backshell  14 , which includes a cable-insertion end  44 , a terminus end  46 , a first side  48 , and a second side  50 . In addition, the backshell  14  includes the top surface  34  and a bottom surface (obstructed from view), which opposes the top surface  34 . Respective terms, such as top, bottom, left, right, front, back, rear, and the like, might be used in this description with reference to the drawings to describe certain parts or regions of the connection system  10 . But these terms are merely descriptive to distinguish one part from another part in the context of the subject figure and are not limiting. 
     In another embodiment, the top portion  18  of the backshell and the bottom portion  28  of the backshell each includes respective channels that mate with one another to form epoxy or solder wells (e.g.,  52  and  60 ). For example, the first side  48  of the backshell  14  includes a first solder well  52  ( FIGS. 1 and 2 ) that is fillable with solder material when the portions  18  and  28  are coupled. The first solder well  52  is formed by a first channel  54  ( FIG. 3 ) positioned along the first-side edge of the top portion  18  and by a second channel  56  positioned along the first-side edge of the bottom portion  28 . 
     The second side  50  of the backshell  14  includes a second solder well that essentially mirrors the first solder well  52  (except for being positioned on the opposing side) and that is also fillable with solder material when the portions  18  and  28  are coupled. The second solder well is formed by a third channel (obstructed from view) positioned along the second-side edge of the top portion  18  and by a fourth channel  58  positioned along the second-side edge of the bottom portion  28 . The first solder well  52  and second solder well serve various functions, such as providing a high-frequency seal and blocking EMI/RF leaks. 
     In another embodiment, the connection system  10  includes a rear well  60  for receiving an epoxy material  62  ( FIG. 1 ), which helps to retain the cable jacket  26  to the backshell  14 . The rear well  60  is formed between the top portion  18  and the bottom portion  28  when the two portions are coupled to one another, and  FIG. 2  depicts a portion of the jacket positioned in the rear well  60 .  FIG. 3  more clearly shows that the bottom portion  28  includes a recessed portion  62  that forms part of a lower wall of the rear well  60 . The top portion  18  includes another recessed portion  64  that generally opposes the bottom-portion recessed portion  62 . The recessed portions  62  and  64  align when the backshell portions  18  and  28  are mated to form the rear well  60 . 
     The electrical connection system might be assembled in various manners, and a process of assembling the connection system will now be described with reference to the various figures. In one embodiment, a step includes prepping a cable assembly by stripping the inner shield  22 , the braided outer shield  24 , and cable jacket  26  flush down to the set of one or more wires  20 . The ferrule  25  is then slid between the inner shield  22  and the braided outer shield  24 , and an illustrative depiction of this finished step is provided by  FIG. 4 . The contacts of the connector  16  might then be prepped (per relevant specs), crimped to the one or more wires  20 , and installed into an insulator  70  of the connector  16  by epoxy tacking into place. The ground wire is then terminated and appropriate electrical tests can be run. 
     Once the cable assembly is coupled to the connector  16 , a potting well  66  of the connector  16  is filled approximately two-thirds full with an epoxy. While the epoxy is still wet, the bottom portion  28  of the backshell is inserted into the potting well until the end  68  of the bottom portion  28  contacts a shoulder of the connector shell. The cable jacket  26  is then pulled back beyond the ferrule  25  (i.e., to expose the non-encased portion  24 B of the outer shield  24 ), and the outer shield is adjusted 360 degrees around the ferrule  25 . 
     Once the braided outer shield  24  is positioned around the ferrule  25  (e.g.,  FIG. 5 ), then the top portion  18  of the backshell is installed by securing fasteners through the aligned holes  19 A-B and  29 A-B. At this point, the braided outer shield  24 , the ferrule  25 , and the inner shield  22  are clamped in the cylindrical channel and between the top portion  18  and the bottom portion  28 , and the non-encased portion  24 B of the braided outer shield  24  is positioned in the internal groove  36 . The jacket  26  is positioned within the rear well  60 , but does not extend into the internal groove  36 . 
     Solder material is then applied to grooves between the backshell  14  and the connector  16  and to the first solder well  52  and the second solder well. In addition, the braided outer shield  24 B is soldered to the backshell by applying solder material in the internal groove  36 . The cable jacket  26  is then secured inside the backshell by filling the rear well  60  with epoxy  62 . 
     The connection system helps to reduce openings and EMI/RF leaks in the braided outer shield  24  and to improve connection at the entrance. In addition a shield-termination system is provided for a small shielded cable that is terminated into a larger connector shell with a reduced loss in signal integrity from EMI/RF leaks. 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Embodiments of our technology have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims.