Abstract:
A sealed cover and plastic cartridge combination for electrical connections providing sealing, strain relief, mechanical retention, electrical insulation and flex relief similar to that achieved using an over-molded design includes a plastic cartridge of integral construction or composed of two or more parts, in either case housing one or more contacts of the connections.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION  
       [0001]     This patent application claims the benefit under 35 USC 119 and 120 of the filing date and priority of provisional U.S. patent application Ser. No. 60/543,426, filed 9 Feb. 2004. 
     
    
     BACKGROUND OF THE INVENTION—DESCRIPTION OF THE PRIOR ART  
       [0002]     A typical over molded electrical cable assembly uses a three step process. First, the wire is soldered or crimped to the contact(s). Second, the wire and contact sub assembly goes through a molding process known as a “pre-mold”. This typically uses a rigid material, usually a thermoplastic such as nylon, to encapsulate the wire and rear portion of contacts. This provides mechanical reinforcement for the contacts and wires, provides electrical insulation, and positions the wires and contacts. Third, the thermoplastic assembly goes through an additional molding process, known as the “over-mold”, where a flexible material, such as vinyl nitrile or PVC, is molded over the thermoplastic and wire assembly. This step adds further encapsulation, flex and strain relief, tamper resistance, and in some cases resistance to fluids.  
         [0003]      FIG. 1  is a schematic representation of a typical over-molded electrical cable according to the prior art.  
         [0004]     Over molding is a cost effective technology for high volume production. For low and medium volume production it is less attractive for the following reasons. First, the cables can not be easily reworked. Second, over molding requires mold tools and mold presses. These costs can be prohibitive for smaller volume cable assemblies. Third, over molded cables have to be factory assembled. This can add costs and delays.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a schematic representation of a typical over-molded electrical cable according to the prior art.  
         [0006]      FIG. 2  is an exploded isometric view illustrating a sealed cover and plastic cartridge package in accordance with the preferred embodiment of the invention.  
         [0007]      FIG. 3  is a broken isometric view of the interior of a portion of a sealed cover part of the invention.  
         [0008]      FIG. 4  is a broken isometric view of the interior of a sealed cover part of the invention together with a plastic cartridge shown therein.  
         [0009]      FIG. 5  is a front elevation of the cartridge illustrated in  FIG. 4 .  
         [0010]      FIGS. 6, 7  and  8  are sequential schematic elevation views of wires being connected to contacts and covered with an over-mold in accordance with the invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0011]     This invention eliminates the aforementioned problems associated with over-molded electrical connectors. A plastic cartridge  16  made of a material such as nylon or polycarbonate that can accept one or more electrical contacts  102  is molded using standard thermoplastic molding technology. This cartridge  16  positions and retains the contacts  102 ; it replaces the pre-mold. A second component, the sealed cover  14 , made from a softer material such as silicone or vinyl nitrile, is molded using established rubber molding technology. After molding the sealed cover is inserted over the plastic cartridge block  12  embracing plastic cartridge  16  by expanding the sealed cover  14  using a tool or fixture. The sealed cover  14  replaces the need for the over-mold.  
         [0012]     The invention duplicates the over molding process with parts that can be manufactured independently and assembled in small quantities. This provides an advantage since the components can be manufactured and stocked in advance and then assembled to order. The assembled connectors can also be reworked.  
         [0013]      FIG. 2  illustrates a sealed cover  14  and a plastic cartridge block  12  in accordance with the invention. The block is preferably composed of four individual plastic cartridges  16  bonded together. Two sets of blocks  12  are preferably used to make the electrical connection.  
         [0014]     As illustrated in  FIG. 3 , the sealed cover  14  uses alignment features on the cartridges  16  to provide mechanical strength to secure the sealed cover on to the plastic cartridge block  12 . Features molded into the inside surface  18  of the sealed cover  14  match features on the outer surface  22  of the plastic cartridge block  12 . This alignment enables the parts to prevent fluids from entering the electrical connection and provides sufficient mechanical strength to prevent the parts from separating under normal use. The thickness of the sealed cover  14  and the hardness of the material used are important for optimal operation. Sealed cover  14  expands to fit over plastic cartridge block  12 . There is a design balance to ensure that sealed cover  14  can be expanded without tearing or stretching on the one hand, but the material must be firm enough to properly cover the plastic cartridge block  12  and remain in place.  
         [0015]     Referring to  FIGS. 6, 7  and  8 ,  FIG. 6  illustrates a contact  102  having a pair of crimpable receivers  104  extending from one end thereof where crimpable receivers  104  are aligned to receive respective wire strands  106  extending out of an insulated jacket portion  107  of an insulated wire  108 . Once wire strands  106  are positioned within crimpable receivers  104 , receivers  104  are crimped about wire strands  106  to mechanically retain wire strands  106  and to effectuate good electrical conductivity as between wire strands  106  and respective crimpable receivers  104 .  
         [0016]     After such crimping has been performed, a premold  110  is moved axially along insulated wire  108  into position over the now crimped crimpable receivers  104  holding wire strands  106  there-within. Finally, an overmold  112  is positioned around premold  110 , as illustrated in  FIG. 8 , at the same axial position respecting insulated wire  108 . Overmold  112  includes a flexible stress/strained relief member  114  integrally molded as a part of overmold  112 . The flexible stress/strained relief member  114  provides flexible relief with respect to the electrical connection maintained by crimpable receivers  104  being crimped about wire strands  106 .  
         [0017]     As illustrated in  FIG. 4 , the complete electrical connector is made by combining the contact  102 , the plastic cartridge block  12  and the sealed cover  14 . A connection has two sides. One side of the connection is called the “plug” and the other is called the “receptacle”. The plug and receptacle have interlocking halves that provide sealing against fluids and mechanical retention. The plug fits in the receptacle.