Patent Publication Number: US-6981897-B2

Title: Waterproof construction for a ground terminal fitting, a method and an apparatus for waterproofing a ground terminal fitting

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a waterproof construction for a ground terminal fitting, a method and an apparatus for waterproofing a ground terminal fitting. 
   2. Description of the Related Art 
   U.S. Pat. No. 6,613,263 discloses a construction for grounding a plurality of wires by bundling the wires together, crimping the bundled wires to one ground terminal fitting and then fixing the ground terminal fitting to a grounding member. 
   A connected portion between the above-described ground terminal fitting and the wires is surrounded by a molding resin to prevent water from entering into cores of the wires. More particularly, as shown in  FIG. 8 , wires  100  are bundled and drawn out from a resin mold  101 . The lateral cross section of each wire  100  is substantially circular. Thus, clearances between the adjacent wires  100  have a shape of a pinnacle in section. It is difficult to fill the resin into such pinnacle-shaped narrow clearances  102 , and tiny clearances  103  are left between the adjacent wires  100  after molding. Thus, water can enter the inside of the resin mold  101  through the clearances  103 . 
   The present invention was developed in view of the above problem, and an object thereof is to prevent water from entering into a resin mold that surrounds a connected portion between a ground terminal fitting and wires. 
   SUMMARY OF THE INVENTION 
   The invention relates to a waterproof construction for a terminal fitting, preferably a ground or battery terminal fitting, for connecting a plurality of bundled wires together with the terminal fitting by surrounding a connected portion of the wires and the terminal fitting by a molding resin. The wires are spaced apart from each other from a connected position with the terminal fitting towards draw-out positions on an outer surface of the molding resin, and the respective wires are drawn out at spaced-part positions on the outer surface of the molding resin. As a result, the molding resin is adhered to the entire outer surface of each wire over the entire circumferences. Accordingly, no clearance exists between the wires and the molding resin, and high waterproof performances can be displayed. 
   The wires preferably are spaced apart from each other along a direction substantially normal to a longitudinal direction of ends of the wires connected with each other. 
   The terminal fitting preferably comprises a connecting portion for connection to an external portion such as a battery post or ground and/or for connection to another terminal fitting. The terminal fitting also comprises an extending portion that includes a wire connection portion. At least part of the wire connecting portion preferably is covered by the molding resin. 
   The invention also relates to a method for waterproofing a connection between a plurality of wires and a ground terminal fitting. The method comprises connecting the wires to at least one ground terminal fitting. The method then comprises surrounding a connected portion between the wires and the ground terminal fitting by a molding resin. More particularly, a wire holding means is provided in a mold. The wires then are placed in the wire holding means so that the wires are spaced apart from each other from a connected position with the ground terminal fitting towards draw-out positions on an outer surface of the molding resin. The molding then is carried out so that the wires are at spaced-part positions on the outer surface of the molding resin in an already molded state. 
   The method may further comprise detachably mounting at least one jig of the wire holding means in the mold for molding. The step of mounting the jig preferably comprises selecting a jig having wire holding portions suitable for the wires connected with the terminal fitting. The jig may become integral to the molding resin in the molding process. 
   The invention also relates to apparatus for waterproofing a connection between a terminal fitting and a plurality of wires by surrounding a connected portion between the wires and the terminal fitting by a molding resin. The apparatus comprises a mold and a wire holding means for holding the wires in the mold. The wiring holding means spaces the wires apart from a connected position with the ground terminal fitting towards draw-out positions on an outer surface of the molding resin. Thus, the wires are drawn out at spaced-part positions on the outer surface of the molding resin. 
   The wire holding means preferably comprises a jig detachably mountable in the mold. Thus, wires having different outer diameters can be accommodated merely by exchanging the jig in a common mold. Accordingly, costs can be reduced as compared to a case where the entire mold is exchanged in accordance with the outer diameters of the wires. 
   The jig preferably has wire holding portions with shapes suitable for the respective wires connected with the terminal fitting. 
   These and other features of the invention will become more apparent upon reading the following detailed description and accompanying drawings. It should be understood that even though embodiments are described separately, single features thereof may be combined to additional embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of a ground terminal fitting according to one embodiment of the invention. 
       FIG. 2  is a horizontal section of the ground terminal fitting. 
       FIG. 3  is a plan view showing wires are connected with the ground terminal fitting. 
       FIG. 4  is a plan view showing a state where the ground terminal fitting having the wires connected therewith is set in a mold for molding. 
       FIG. 5  is a partial longitudinal section showing the closed mold. 
       FIG. 6  is a perspective view of the mold and a wire holding means. 
       FIG. 7  is an end view showing wire draw-out positions on an outer surface of a molding resin. 
       FIG. 8  is an end view showing wire draw-out positions on an outer surface of a molding resin in a prior art waterproof construction. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A battery or ground terminal fitting according to the invention is identified by the numeral  10  in  FIGS. 1 to 7 . The terminal fitting  10  is formed, for example, by bending, folding and/or embossing a conductive metallic plate material-stamped or cut out into a specified shape. More particularly, the terminal fitting  10  includes a substantially ring-shaped connecting plate  11  and an extension  15  projecting substantially radially out from the outer periphery of the connecting plate  11  and substantially flush with the connecting plate  11 . 
   A locking hole  12   a  penetrates the connecting plate  11  substantially normal to the plane of the connecting plate  11 . At least one locking piece  12   b  is formed by cutting the connecting plate  11  and bending a cut section out of the plane of the connecting plate  11 . Two pressing pieces  13  project up from the outer periphery of the connecting plate  11 . Connecting plates  11  of two ground terminal fittings  10  can be placed concentrically placed over one another so that the locking hole  12   a  of the upper connecting plate  11  and the locking piece  12   b  of the lower connecting plate  11  interlock to prevent relative circumferential movements of the connecting plates  11 . Additionally, the outer periphery of the upper connecting plate  11  is held axially between the lower connecting plate  11  and the pressing pieces  13  thereof to prevent the connecting plates  11  from being separated axially. In this way, the two ground terminal fittings  10  are coupled to each other with the extensions  15  thereof circumferentially displaced and with center holes  14  substantially concentrically aligned. A bolt (not shown) of a grounding member (not shown) for grounding the ground terminal fittings  10  or a battery post of a battery (not shown) for connecting the battery terminal fittings  10  is inserted into the center holes  14 . 
   A wire connection portion is formed near the extending end of the extension  15  and has a known crimping portion  16  with crimping pieces that project up from opposite edges of a bottom plate. The crimping portion  16  includes a wire barrel  16   a  near the connecting plate  11  and an insulation barrel  16   b  farther from the connecting plate  11  and at the extending end of the extension  15 . 
   The crimping portion  16  is crimped, bent or folded into connection with ends of two wires  17   a ,  17   b  having different outer diameters. The respective wires  17   a ,  17   b  have cores  18   a ,  18   b  covered by resin insulation coatings  19   a ,  19   b . The insulation coatings  19   a ,  19   b  are stripped to expose the cores  18   a ,  18   b  at the ends of the respective wires  17   a ,  17   b . The wires  17   a ,  17   b  are placed substantially side-by-side in close contact with each other on the bottom plate of the crimping portion  16  so that their longitudinal axes are substantially parallel, and are secured by the crimping pieces of the crimping portion  16 . Thus, the ends of the insulation coatings  19   a ,  19   b  of the two wires  17   a ,  17   b  are secured to the insulation barrel  16   b  while being held side-by-side in close contact. Similarly, the two exposed cores  18   a ,  18   b  are secured to the wire barrel  16   a  while being held side by side in close contact. The two wires  17   a ,  17   b  secured to the crimping portion  16  extend from the extending end of the extension  15  substantially in the same direction as the extending direction ED of the extension  15 . Thus, the wires  17   a ,  17   b  are spaced from each other in a direction lying in the plane of the draw-out surface  21 . 
   A connected portion CP of the ground terminal fitting  10  and the wires  17   a ,  17   b  is to be surrounded by a molding resin  20  for waterproofing. The molding resin  20  surrounds most of the extension  15  excluding a coupling end to the connecting plate  11 , but including substantially the entire connected portion CP with the wires  17   a ,  17   b . The wires  17   a ,  17   b  are drawn out of the molding resin  20  at laterally spaced-apart positions through a draw-out surface  21  at a side of the molding resin  20  substantially opposite the connecting plate  11 . The draw-out direction is substantially parallel with the longitudinal direction of the ends of the wires  17   a ,  17   b  connected with the crimping portion  16  and parallel with the extending direction ED of the extension  15 . 
   As described above, the two wires  17   a ,  17   b  are held side-by-side in close contact at their portions connected with the ground terminal fitting  10 , whereas they are drawn out on the draw-out surface  21  of the molding resin  20  at positions spaced apart laterally along a direction substantially normal to the extending direction ED. To realize this arrangement, the two wires  17   a ,  17   b  are arranged obliquely and away from each other from the crimping portion  16  towards the draw-out surface  21  of the molding resin  20 . The wires  17  preferably are spaced from each other by more than about ⅕ of the wire diameter. 
   The extension  15  of the ground terminal fitting  10  and the ends of the wires  17   a ,  17   b  are set in a cavity  25  of a mold  22  after the two wires  17   a ,  17   b  are connected. The mold  22  is opened and closed by moving an upper mold  24  with respect to a lower mold  23 . A jig  26  is detachably mounted in the lower mold  23 . A surface of the jig  26  facing the cavity  25  serves as a molding surface  27  for forming a part of the draw-out surface  21  of the molding resin  20 . Substantially semicircular large and small holding grooves  28   a ,  28   b  are formed substantially parallel with each other along the extending direction ED in the upper surface of the jig  26 . The holding grooves  28   a ,  28   b  communicate with the cavity  25  and have cross-sections substantially conforming to part of an outer shape of the wires  17   a ,  17   b . Inner diameters of the holding grooves  28   a ,  28   b  substantially equal the outer diameters of the two wires  17   a ,  17   b . Fitting grooves  29   a ,  29   b  having the substantially same dimensions and shape as the holding grooves  28   a ,  28   b  are formed in the upper surface of the lower mold  23  and concentrically communicate with the holding grooves  28   a ,  28   b.    
   The upper mold  24  also is formed with a jig  30 . The jig  30  of the upper mold  24  has a substantially vertically symmetrical shape with respect to the jig  26  of the lower mold  23  and includes a molding surface  31  substantially continuous and flush with the molding surface  27  of the lower mold  23 . Substantially semicircular holding grooves  32   a ,  32   b  are provided in the upper mold  24  and substantially correspond to the holding grooves  28   a ,  28   b  of the lower mold  23 . Thus, the holding grooves  28   a ,  28   b  have substantially semicircular cross sections. No further description is given thereon. Further, fitting grooves  33   a ,  33   b  are formed in the lower surface of the upper mold  24  and substantially correspond to the fitting grooves  29   a ,  29   b  of the lower mold  23 . Thus, the fitting grooves  33   a ,  33   b  have substantially semicircular cross sections conforming to part of an outer shape of the wires  17   a ,  17   b.    
   The ground terminal fitting  10  and ends of the wires  17   a ,  17   b  are set in the cavity  25  of the lower mold  23  with the mold  22  opened (see  FIG. 4 ). At this time, the wires  17   a ,  17   b  are fit in the corresponding holding grooves  28   a ,  28   b  and fitting grooves  29   a ,  29   b . Thus, the wires  17   a ,  17   b  are positioned away from each other from the crimping portion  16  towards the jig  26  in the cavity  25 . The mold  22  then is closed by moving at least one of the molds  23  and  24  with respect to the other. Thus, laterally spaced sections of the two wires  17   a ,  17   b  are held in holes formed by the upper and lower holding grooves  28   a ,  32   a ,  38   b ,  32   b  and the upper and lower fitting grooves  29   a ,  33   a ,  29   b ,  33   b.    
   Molten resin then is filled in the cavity  25  and solidified. Accordingly, the molding resin  20  defines an integral matrix surrounding and engaging the connected portion of the ground terminal fitting  10  and the wires  17   a ,  17   b . In this way, waterproofing to the ground terminal fitting  10  is completed. 
   As described above, two wires  17   a ,  17   b  are bundled and connected together with the ground terminal fitting  10 , and this connected portion CP is surrounded by the molding resin  20 . The wires  17   a ,  17   b  are spaced from each other from the connected position CP with the ground terminal fitting  10  towards the draw-out surface  21  of the molding resin  20  and are drawn out at the spaced-apart positions on the draw-out surface  21  of the molding resin  20 . The molding resin  20  adheres to the outer surfaces of the wires  17   a ,  17   b  over substantially the entire circumferences. Thus, no clearance is left between the wires  17   a ,  17   b  and the molding resin  20 , and high waterproof performances can be displayed. 
   The wire holding means includes jigs  26 ,  30  detachably mounted in the mold  22 . Thus, wires  17   a ,  17   b  of different outer diameters can be accommodated merely by exchanging the jigs  26 ,  30  in the common mold  22 , so that jigs  26 ,  30  corresponding to outer diameters of the wires  17   a ,  17   b  are employed. Accordingly, costs can be reduced as compared to a case where the entire mold  22  is exchanged to match outer diameters of the wires  17   a ,  17   b.    
   The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments also are embraced by the technical scope of the invention as defined by the claims. Beside the following embodiments, various changes can be made without departing from the scope and spirit of the present invention as defined by the claims. 
   Wires having different outer diameters are connected in the foregoing embodiment. However, the invention is also applicable to a case where wires having the same outer diameter are connected. 
   Two wires are connected in the foregoing embodiment. However, three or more wires may be connected. In such a case, wire draw-out positions on the outer surface of the molding resin may align the wires in a row, or may provide an offset arrangement of the wires. 
   Two ground terminal fittings are coupled in the foregoing embodiment. However, the invention also applies to a case where a ground terminal fitting is not coupled to another ground terminal fitting. 
   The wire connecting means of the foregoing embodiment has a crimping portion with open barrels. However, the invention also applies to a crimping portion with closed barrels or by another connecting means, such as insulation-displacement portions, soldered portions, welded portions, etc. 
   The wire holding means is detachably mountable in the mold in the foregoing embodiment, but may be integrally or unitarily formed in the mold. 
   The wires are drawn out substantially in parallel from the outer surface of the molding resin in the foregoing embodiment. However, they may be drawn in different directions from the outer surface of the molding resin. 
   The ground terminal fitting has only one connected portion with the wires in the foregoing embodiment, but may have more connected portions. 
   The jigs are separated from the wires after molding in the foregoing embodiment. However, the jigs may become integral to the molding resin according to the invention. In short, the jig may be set in the cavity of the mold for molding to be partly or entirely embedded in the molding resin.