Patent Publication Number: US-8992258-B2

Title: Electrical cable connector shield with positive retention locking feature

Description:
TECHNICAL FIELD OF THE INVENTION 
     The invention generally relates to electrical cable assembly, and more particularly relates to an electrical cable assembly having a connector shield with a positive retention locking feature. 
     BACKGROUND OF THE INVENTION 
     Applications are arising in the automotive industry that require the use of shielded, e.g. coaxial, electrical cables. These cables may be used for high voltage power transmission as well as digital data transmission within the vehicle. Connecting these shielded cables necessitates connecting the inner core conductors as well as the outer sheath (shield) conductors. 
     U.S. Pat. No. 8,323,055 issued to Plate, et. al. on Dec. 4, 2012 and U.S. Pat. No. 7,868,251 issued to Gladd, et. al. on Jan. 11, 2011 show an electrical cable assembly that includes a connector that is configured to electrically connect both the inner core and the outer sheath of a shielded cable. The connector includes a female shield that is connected to the outer sheath and a male shield that is configured to mate with the female shield. It has been observed by the inventors that mechanical shock and vibration experienced by these types of connectors in an automotive environment may cause fretting corrosion between the male and female shields. A shielded electrical cable assembly capable of withstanding the shock and vibration profile of an automobile without experiencing fretting corrosion is therefore desired. 
     The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with one embodiment of this invention, an electrical cable assembly is provided. The electrical cable assembly includes an electrical cable having an inner core and a surrounding outer sheath each running the length of the electrical cable. The electrical cable assembly also includes a female exterior shield that is connected to the outer sheath at a closed end. The female exterior shield has an open end that is defined about a central axis. The female exterior shield defines an aperture having an aperture axis that is generally perpendicular to the central axis. The electrical cable assembly further includes a male exterior shield that is adapted to be connected to the female exterior shield. The male exterior shield is sized to fit within the open end of the female exterior shield. The male exterior shield defines a flexible contact that is adapted to closely engage an interior surface of the female exterior shield, thereby providing an electrical connection between the two shields. The male exterior shield additionally defines a flexible protrusion that is designed to align with and snap into the aperture, thereby providing a mechanical connection between the two shields and forming a positive retention locking feature. The flexible protrusion and the flexible contact flex along axes that are generally orthogonal to one another so as to interact with the female exterior shield substantially independently of one another. 
     In accordance with another embodiment of this invention, the aperture is characterized as a generally circular hole in a side wall of the male exterior shield. The flexible protrusion includes a generally circular convex bump that is designed to align with and snap into the aperture and a flexible fixed beam on which the convex bump is disposed. 
     In accordance with yet another embodiment of this invention, the female exterior shield defines a pair of apertures, located one opposite the other, wherein the pair of apertures shares a common aperture axis. The male exterior shield likewise defines a pair of flexible protrusions designed to align with and snap into the pair of apertures. The male exterior shield defines a pair of flexible contacts located one opposite the other. The flexible protrusions and the flexible contacts flex along axes that are generally orthogonal to one another so as to interact with the female exterior shield substantially independently of one another. 
     Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The present invention will now be described, by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an electrical cable assembly in accordance with one embodiment; 
         FIG. 2  is an exploded perspective view of the electrical cable assembly of  FIG. 1  in accordance with one embodiment; 
         FIG. 3  is cross sectional side view of the electrical cable assembly of  FIG. 1  in accordance with one embodiment; and 
         FIG. 4  is a partially exploded perspective view of an electrical cable assembly in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An electrical cable assembly is presented herein that includes a positive retention locking feature that is designed to inhibit relative motion between two interconnected shields. 
       FIGS. 1-3  illustrate a non-limiting example of an electrical cable assembly  10 , hereafter referred to as the assembly  10 . The assembly  10  in the instant example is designed for use in a motor vehicle in a high voltage/high current application. The assembly  10  includes an electrical cable  12  having an electrically conductive inner core  14  this is surrounded by an inner insulation layer  16  formed of a dielectric material. The inner core  14  is formed of multiple stands of a material having a relatively high conductivity, such as copper or aluminum. The inner insulation layer  16  is surrounded by an electrically conductive outer sheath  18  that is formed of woven strands of a material having a relatively high conductivity, such as copper or aluminum. The outer sheath  18  is itself surrounded by an outer insulation layer  20  formed of a dielectric material. The electrical cable  12  may be generally referred to as a coaxial cable or a shielded cable. The materials and methods used to construct shielded electrical cables are well known to those skilled in the art. 
     The assembly  10  also includes a female exterior shield  22 , hereafter referred to as the female shield  22 . The female shield  22  defines a first opening  24  about a central axis A that is connected to the outer sheath  18  of the electrical cable  12 , thereby forming a closed end  24 . The first opening  24  is crimped to the outer sheath  18  to form the closed end  24 . As best shown in  FIG. 3 , the assembly  10  may also include a metallic ferrule  26  that is disposed between the first opening  24  and the outer sheath  18  prior to crimping the female shield  22  to the electrical cable  12 . The ferrule  26  is configured to improve the mechanical and electrical connection between the female shield  22  and the electrical cable  12 . The female shield  22  defines a second opening  28  about the central axis A, thereby forming an open end  28  of the female shield  22 . The second opening  28  is generally larger than the first opening  24 , and so the female shield  22  may be characterized as generally bell-shaped. The female shield  22  is formed of a metallic material, such as C425 copper alloy, using a deep draw stamping process to form a seamless shield. The female shield  22  may be plated, such as with a tin-based plating, to enhance corrosion resistance. As best shown in  FIG. 2 , the female shield  22  defines a pair of apertures  30 , or holes  30  located one opposite the other in opposing side walls  32  of the female shield  22 . The pair of apertures  30  shares an aperture axis B that is generally perpendicular to the central axis A of the female shield  22 . The apertures  30  in the instant example are characterized as a generally circular hole. 
     The assembly  10  further includes a male exterior shield  34 , hereafter referred to as the male shield  34 . The male shield  34  is adapted to be connected to the female shield  22  and is sized to closely fit within the open end  28  of the female shield  22 . The male shield  34  is formed from a sheet of a metallic material, such as C110 copper alloy by stamping and bending the male shield  34  to the desired shape. The male shield  34  may also be plated, such as with a tin-based plating, to enhance corrosion resistance. The male shield  34  defines a plurality of flexible contacts  36  that is adapted to closely engage and contact an interior surface  38  of the female shield  22 , thereby providing an electrical connection between the female shield  22  and the male shield  34 . At least a pair of flexible contacts are disposed in opposite side walls of the male shield. Due to perspective of the drawings in  FIGS. 1-3 , the second flexible contacts in the opposite side wall are not visible. The free end  42  is configured to contact the female shield  22 . Other types of flexible contacts  36  that are well known to those skilled in the art could alternatively be used. The flexible contacts  36  may be formed during the stamping and bending processes. 
     As best shown in  FIG. 3 , the male shield  34  additionally defines a pair of flexible protrusions  44  in opposite side walls of the male shield  34  and as best shown in  FIG. 2  are generally orthogonal to the flexible contacts  36 . The flexible protrusions  44  are designed to align with and snap into the apertures  30 , thereby providing a mechanical connection between the female shield  22  and the male shield  34 . This mechanical connection between the flexible protrusion  44  and the aperture  30  at least provides the benefit of inhibiting micro-motion between the female shield  22  and the male shield  34  caused by mechanical shock or vibration, thereby reducing the likelihood of fretting corrosion occurring between the female shield  22  and the male shield  34 . 
     The flexible protrusions  44  in the instant example include a generally circular convex bump  46  that is designed to align with and snap into the aperture. The convex bump  46  may be characterized as having a hemispherical or partially spherical shape. The flexible protrusions  44  also include a flexible fixed beam  48  on which the convex bump  46  is disposed. The beam  48  may be formed removing a portion of the male shield  34  on each side of the beam  48  during the stamping process and the convex bump  46  may be formed by embossing a portion of the beam  48 , also during the stamping process. 
     The male shield  34  is sized to closely fit within an interior cavity  50  formed by the open end  28  of the female shield  22 . The flexible protrusions  44  are sized to mechanically interfere with the female shield  22  when they are in a non-flexed condition. Without prescribing to any particular theory of operation, when the male shield  34  is inserted into the cavity  50  of the female shield  22 , the leading edge of the bump of the flexible protrusion contacts the inner surface of the female shield  22 . The beam  48  flexes inward until the apex of the convex bump  46  contacts the interior surface  38 . As the male shield  34  is further inserted into the female shield  22 , the bump aligns with the aperture and the beam  48  flexes outward snapping the bump into the aperture. 
     The flexible protrusions  44  flex along axis B and the flexible contacts  36  flex along axis C. Axes B and C are generally orthogonal to one another, and so the flexible protrusions  44  interact with the female shield  22  substantially independently of the flexible contacts  36 . 
     The assembly  10  further includes an electrical terminal  52  that is connected to the inner core  14  of the electrical cable  12 . The electrical terminal  52  in the instant example is a female terminal having a terminal insert  54 . The female terminal is configured to mate with a male blade terminal (not shown). The electrical terminal  52  is enclosed within the female shield  22  and the male shield  34 . Alternative embodiments of the assembly may use another electrical terminal type as is well known to those skilled in the art. 
     The assembly  10  also includes a dielectric insulating member  56 , hereafter referred to as the insulator  56 . The insulator  56  is disposed within the male shield  34 . The insulator  56  is configured to electrically isolate the electrical terminal  52  from the male shield  34  and to mechanically support and secure the electrical terminal  52  within the male shield  34 . The insulator  56  defines cutouts  58  that allow the flexible protrusions  44  to flex inward. The male shield  34  may also define features, such as inward protrusions  60 , that are configured to secure the insulator  56  within the male shield  34 . 
     The assembly  10  additionally includes an insulative connector body  62  that is configured to be connected to another connector body (not shown) that contains the mating terminal for the electrical terminal  52 . The male shield  34  defines a plurality of tabs  64  that are configured to engage the connector body and secure the male shield  34  within the connector body. The male shield  34  also defines a plurality of contacts  66  that are configured to provide an electrical connection between the male shield  34  and electrical conductors in the connector body  62 . 
     The non-limiting examples of the electrical cable assembly  10  shown in  FIGS. 1-3  include a female shield  22  and a male shield  34  having a generally rectangular shape and multi-strand cable to be used in a high voltage/high current application. It should be understood that other embodiments of the assembly  10  are envisioned that include shields having square or circular shapes. Alternatively, the electrical cable may have a single solid conductor or, such as a coaxial cable or may have multiple separately insulated conductors within an outer sheath  18 , such as a twin axial cable and may be used for analog or data communication applications. Still alternatively, the male shield  34  may be connected to an outer sheath  18  of another electrical cable  12 . 
     Accordingly, an electrical cable assembly  10  is provided. The electrical cable assembly  10  includes a male shield  34  and a female shield  22  that is configured to connect to the outer sheath  18  of a shielded electrical cable  12  in order to maintain electrical continuity of the shield across a connection of the inner core  14  of the shielded electrical cable  12 . The male shield  34  includes a flexible protrusion that snaps into an aperture in the female shield  22  to mechanically connect the female shield  22  and the male shield  34  to one another. The male shield  34  also includes a flexible contact that is generally located orthogonal to the flexible protrusion and provides an electrical connection between the female shield  22  and the male shield  34 . Because the location of the flexible protrusion and the flexible contacts  36  are orthogonal, the forces exerted by the flexible protrusion on the female shield  22  and the male shield  34  are substantially independent of the forces exerted by the flexible contact on the female shield  22  and the male shield  34 . 
     While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. Moreover, the use of the terms first, second, etc. does not denote any order of importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.