Patent Publication Number: US-6210210-B1

Title: Flat conductor termination device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to an electrical connector. The invention more particularly concerns a device for the termination of a flat conductor of a flat cable. 
     2. Discussion of the Background 
     One of the most undesirable occurrences in the automotive industry is the recall of vehicles due to the presence of a defect or a potential defect. The recall of vehicles is undesirable since it is costly and tarnishes the reputation of the manufacturer. Many of the recall notices concern the electrical system of the recalled vehicles. It is believed that an overwhelming majority of the electrical system recall notices concern the improper or defective crimping of a box contact to stranded conductors of a cable. Typically, an improper or defective crimp involves either an over-crimping or an under-crimping of the box contact to the stranded conductors of the cable. 
     An over-crimped wire can cause the individual conductor strands of the wire to break and fray, thus causing the electrical circuit to eventually fail due to a short or open circuit. An under-crimped cable can lead to the oxidation and corrosion of the individual strands of the cable thus causing an open circuit since electricity does not flow from the conductors to the box contact at the location of the crimp. 
     Typically, many cables are grouped together in a harness assembly. Each cable is individually terminated in its respective box contact. Then the harness assembly is routed throughout the body of the vehicle. The termination of the cables is labor intensive. 
     In spite of the problems associated with box contacts, box contacts are a commodity item in the automotive industry and, as such, are well understood and have gained wide acceptance. In practice it is typical to have many of the box contacts inserted into an insulative housing so as to simplify the almost simultaneous connection of many electrical circuits. FIG. 4 is a perspective view of a typical box contact  80 . FIG. 5 is a view of FIG. 4 showing a crimp  82  of the box contact  80  to the conductors  96  of the cable  98  and a strain relief crimp  84  between the box contact  80  and the insulative layer  94  of the cable  98 . To complete the electrical circuit a post is introduced into the box contact. Thus, ideally, the stranded conductors  96  make electrical contact with the box contact  80  at the crimp  82  of the box contact  80  and then the box contact  80  makes electrical contact with the post (not shown) via a conductive flexible tab  86  located in a box structure  89  of the box contact  80 . The box contact  80  is so named since its box structure  89  has a first side  81 , a second side  83 , a third side  85 , and a fourth side  87 . The box structure  89  forms an aperture  88  which terminates at a rim  90 . The first side  81  includes the flexible tab  86 . The box structure  89  further has an interior surface  91  and an exterior surface  92 . 
     Therefore, there is a need for a more reliable electrical harness assembly. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide a reliable electrical connection between the conductors of the cable and the post. 
     It is still another object of the invention to provide an electrical connection device which is economical. 
     Yet another object of the invention is to provide an electrical connection device which employs the box contact structure. 
     It is a further object of the invention to provide an electrical connection device which is easy to install. 
     It is still another object of the invention to provide an electrical connection device which does not directly crimp the conductors. 
     In one form of the invention, the electrical connection device employs the use of a flat conductor of a flat cable in conjunction with a modified box contact. Only now, with the recent advent of flat cable having flat conductors sandwiched between insulative layers, can such cabling be used economically in industrial applications. A flat cable design is disclosed in U.S. Pat. No. 6,026,563, which is hereby incorporated herein by reference. FIG. 6 is a perspective view of a flat cable  100  having flat conductors  102  which have a width greater than their thickness. The flat conductors  102  are retained in the flat cable  100  by the upper and lower insulative layers  104 ,  106  which are sonically welded to each other so as to form a unified insulative layer  108 . Thus, the flat conductors  102  have no adhesive residue which must be removed so as to ensure a reliable electrical connection between itself and another component or device. 
     Sonically welded flat cable is capable of carrying relatively large current loads, is economically competitive, is flexible, is light in weight, and has a low profile. The low profile aspect of flat cable makes it an ideal candidate for electrical cabling to be used in headliner, dashboard, and door insert installations of automobiles. The low profile of flat cable enables the headliner and doors of automobiles to become thinner thus increasing passenger space. Furthermore, the inline spacing of the conductors of the flat cable provides for the gang installation of conductors into respective box contacts and also eliminates the crimp of the box contact directly to the conductor, which is a cost savings. Thus, sonically welded flat cabling is superior to traditional stranded conductor wire in certain respects and as such has extensive industrial applicability. Therefore, ideally, flat cable would be used in place of stranded conductor wire while maintaining the use of the widely accepted box contact type of structure. The automotive industry is just one example of the industrial applicability of flat cable and the termination of the flat conductor of the flat cable. 
     Further features of the device of the invention include a box structure at one end of the box contact and a strain relief structure at another end of the box contact. The box structure includes a first side, a second side, a third side, and a fourth side so as to form an aperture. The first side includes a flexible tab extending into the aperture. The flexible tab has resilient properties. The third side opposes the first side. The strain relief structure is attachable directly to a surface of the insulative layer, where the insulative layer covers the conductor. Thus, the strain relief structure applies a compressive force to the composite structure of the insulative layer covering the conductor. The flat conductor is extendable through the aperture and is positionable adjacent the third side of the box structure. 
     In use, a post is introduced into the aperture of the box contact. Upon insertion, the post deflects the flexible tab. The deflected, resilient, flexible tab compresses the post against the flat conductor and the flat conductor is urged toward the stationary third side. Therefore the post contacts the flat conductor. The post then conveys electricity to another device. Thus, the conductor makes direct electrical contact with the post. Therefore, the primary purpose of the box contact is not to convey electricity, but the box contact can be modified so as to conduct electricity. 
     Thus, the device of the invention is superior to existing box contacts. The termination device of the invention eliminates an electrical component (the box contact) and two electrical connections (conductor to box contact crimp, and box contact to post) as compared to the prior art, and replaces them with a direct electrical connection between the conductor and the post. A modified box contact remains, but the box conductor need not conduct electricity. Specifically, the troublesome electrical connection between the box contact crimp and the stranded conductors has been eliminated. Thus, the device of the invention is more reliable than the prior art device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is a side view of a flat conductor box contact and a post; 
     FIG. 2 is a side view of the flat conductor box contact of FIG. 1 with the post engaged; 
     FIG. 3 is a cross-sectional view of the flat conductor box contact of FIG. 2; 
     FIG. 4 is a perspective view of a typical box contact; 
     FIG. 5 is a view of the typical box contact of FIG. 4 attached to stranded conductors of an insulated cable; and 
     FIG. 6 is a perspective view of a typical flat cable after an end portion has been stripped to expose the flat conductors. 
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1-3 thereof, an embodiment of the present invention is a flat conductor termination device  70 . 
     FIG. 1 is a side view of the flat conductor termination device  70  which may also be known as a flat conductor box contact. Also shown is a post  60  which mates with the termination device  70 . FIG. 1 shows the flat conductor  102  of the flat cable  100  passing through the aperture  88  of the box structure  89 . The box structure  89  shown in FIGS. 1 and 2 is similar to the box structure shown in FIGS. 4 and 5. The flat conductor  102  is bent around the rim  90  of the box structure  89  of the termination device  70  and exists adjacent an exterior surface  92  and an interior surface  91  of a third side  85 . Unlike the box contact  80  shown in FIGS. 4 and 5, the termination device  70  shown in FIGS. 1 and 2 does not have a crimp  82 . 
     The termination device  70  has a strain relief crimp  84  which crimps onto the insulative layer  108  of the flat cable  100 . A flexible tab  86  projects from a first side  81  of the box structure  89  of the termination device  70 . The flexible tab  86  may be cut away from a portion of the first side  81  which is later bent so as to project into the aperture  88  or the flexible tab  86  may be a resilient member such as an elastomer or rubber material which is attached to the first side  81 . The flexible tab  86  is shown in phantom line since the fourth side  87  blocks direct view of the flexible tab  86  from the side. Also, a portion of the flat conductor  102  which is located within the aperture  88  is shown in phantom line. 
     FIG. 3 is a cross-sectional view of the termination device  70  as shown in FIG.  2 . FIG. 3 clearly shows the direct contact of the strain relief crimp  84  and the insulative layer  108 , where the portion of the insulative layer  108  covers the conductor  102 . Thus, the strain relief crimp  84  applies a compressive force to the insulative layer  108  and the conductor  102 . Furthermore, FIG. 3 clearly shows the generous line of contact  103  between the post  60  and the conductor  102 . 
     In practice, the post  60  is introduced into the aperture  88  of the termination device  70 . When the post  60  is fully engaged with the aperture  88  of the termination device  70 , the flexible tab  86  is deflected or deformed as shown in FIGS. 2 and 3. The resiliency of the deflected or deformed flexible tab  86  causes the post  60  to be pushed or urged against the flat conductor  102  so as to form a reliable electrical connection. Since the post  60  directly contacts the flat conductor  102 , the termination device  70  need not be made of a conductive material. The post  60  then conveys the electrical signal or current to other devices. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.