Patent Publication Number: US-2007111577-A1

Title: Male/female connector assembly for connecting electrical conductors

Description:
RELATED APPLICATIONS  
      The present application is a continuation of U.S. application Ser. No. 11/049,838, filed Feb. 1, 2005, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60/647,724 filed Jan. 26, 2005 which are incorporated herein by reference as if set forth in its entirety. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention comprises a connector for connecting electrical conductors, and in particular, a connector for use in the tractor/trailer industry, so that the conductors are maintained in protected contact.  
      2. Brief Description of the Field  
      Many connector designs have been proposed for use in connecting electrical conductors. Many of these connectors are very effective in the applications for which they are designed. Unfortunately, a connector designed for connecting an electrical conductor to a household outlet is not likely to be effective when used as a connector for heavy equipment, such as, over-the-road semi-trailer trucks and the like. Connectors for such applications must be watertight and must be resistant to separation under conditions of vibration and the like. Further, such connectors must be rugged to withstand abrasion and other detrimental contacts during use.  
      Connectors used in semi-trailers or tractors are frequently used in the electrical harness assemblies of such vehicles. Such connectors are subjected to almost continual vibration and are exposed to water, salt water, abrasive materials and the like. It is vital that such connectors remain in effective electrical connection to ensure safe operation of the vehicles. Connectors of the type disclosed here are often used in so-called “semi-permanent” applications in the trucking industry where it is important that the connection stay securely connected for long periods of time, during often harsh conditions. However, it is also important that they be able to be connected without significant difficulty. It is preferable, then, that an electrical connector assembly require an insertion force which is substantially less than the force required for disengaging the female and male components of the connector.  
      Another deficiency of prior connectors is their size. Conventional connectors with seven 0.180 inch pins have typically been round and at least 1.25 inches in diameter. There exists a need, however, in the trailer industry for harness connectors having a smaller form factor, and in particular, for a connector with seven 0.180 inch pins that have a height of less than 1.1 inches, preferably less than 1.05 inches. The need for such a product has been well known in the industry for at least 15 months. Despite this need, until the present invention, limitations in conventional injection molding processes and connector designs have made it impractical to reduce the size of the connector body. For example, it was previously considered necessary to design connector bodies so as to provide a substantial buffer zone around the wires leading to the terminals in the connector. One reason for this is that the wires tend to become displaced during the injection molding process. If the wires move too close to the surface of the connector body during the molding process, the manufacturing process frequently leaves the wire exposed through a side wall of the connector, rendering the part defective and useless.  
      Another deficiency in prior art connectors is that the injection point for injecting the mold tends to leave a substantial protuberance, which must be removed, increasing the cost of manufacture.  
      And, while many attempts have been made to develop improved connectors for electrical conductors for use in semi-trailers or tractors and many processes have been used to make such connectors, all of the prior connectors used identical materials for both the male and female connector bodies. Typically, a polyvinyl chloride plastic (“PVC”) having a hardness of 60 A to 75 A on the Shore hardness scale was used.  
      All of the major commercially used connector assemblies for the tractor/trailer industry require a separate clamp, pin or other device to ensure a strong, well-sealed semi-permanent connection. This is a serious drawback for those connector assemblies because the clamps are cumbersome and awkward to use and, frequently, are simply not used by truckers, resulting in a high risk of electrical failure. Thus, notwithstanding the availability of a variety of connectors, a need remains for an electrical conductor connector that can ensure reliable waterproof contact during use, as well as provides a viable semi-permanent connection, even when an external clamp is not used. A need also remains for connectors for harness assemblies having a reduced form factor.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a semi-permanent connector assembly and a method of manufacturing the same. To this end, a connector assembly is provided comprising a male connector and a female connector. The male connector comprises at least one conductive terminal held by a male plug body including a head portion and a gripping portion. The head portion includes a plurality of raised elements extending radially outward from the head portion. The female connector comprises at least one mating conductive terminal held by a female plug body including a receiving portion and a gripping portion. The receiving portion is adapted to receive the head portion of the male connector and includes a plurality of recessed areas adapted to interlock with the raised elements of the head portion. The at least one conductive terminal held by the female plug body is configured to mate with the at least one conductive terminal of the male plug body when the head portion is received by the receiving portion.  
      Preferably, the male plug body is made from a substantially rigid plastic and the female plug body is made from a flexible plastic. Preferably, the male plug body has a hardness that is greater than about 80 A on the Shore hardness scale, more preferably greater than 85 A and less than 100 A, and even more preferably about 90 A or greater. Preferably the hardness of the female plug body is less than about 80 A, more preferably greater than or equal to about 60 A and less than or equal to about 80 A, and even more preferably about 75 A.  
      The raised elements may comprise, for example, a plurality of saw-tooth shaped ridges. However, other shapes may also be employed. The plurality of raised elements preferably comprise a D-shaped O-Ring, as shown in the figures and drawings, as the forward-most raised ridge.  
      In a preferred embodiment, the head portion preferably comprises a wiper seal blade extending radially from the head portion at its distal end, or aft of the plurality of raised ridges. Further, the receiving portion preferably has no corresponding recessed area for receiving the wiper seal.  
      Preferably the head portion and the gripping portion of the male plug body are integrally formed in an injection molding process. Similarly, the receiving portion and the gripping portion of the female plug body are also preferably integrally formed in an injection molding process. Preferably, the gripping portions of the male and female plug bodies are mirror images of one another. In a particularly preferred embodiment, the plug bodies have rounded lateral walls with lateral ribs extending along a majority of the length of the respective plug bodies. Further, the plug bodies preferably have flat top and bottom portions. With the foregoing construction, a semi-permanent 7-pin connector assembly employing 0.180 inch pins may be made having a height of less than 1.100 inches, and even less than 1.05 inches, without having the wires move to the surface of the plug body during the molding process.  
      Further objects, advantages, and desirable features of the invention will be better understood from the following description considered in connection with the accompanying drawings in which various embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. 
    
    
     DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a top view of an embodiment of a male connector of the present invention.  
       FIG. 2  is frontal view of the male connector of  FIG. 1 .  
       FIG. 3  is an enlarged view of  FIG. 2 .  
       FIG. 4  is a perspective view of the male connector of  FIG. 1 .  
       FIG. 5  is an enlarged view of  FIG. 1 .  
       FIG. 6  is a side view of the male connector of  FIG. 1 .  
       FIG. 7  is an enlarged view of  FIG. 6 .  
       FIG. 8  is a top view of an embodiment of a female connector of the present invention.  
       FIG. 9  is a frontal view of the female connector of  FIG. 8 .  
       FIG. 10  is a partial sectional side view of the female connector of  FIG. 8  wherein the receiving portion and terminals are shown in cross section.  
       FIG. 11  is a perspective view of the female connector of  FIG. 8 .  
       FIG. 12  is a side view of the female connector of  FIG. 8 .  
       FIG. 13  is side view of a female load bar head used to form an embodiment of a female connector of the present invention.  
       FIG. 14  is an enlarged view of the female load bar head of  FIG. 13 .  
       FIG. 15  is a perspective view of the female load bar head of  FIG. 13 .  
       FIG. 16  shows female load bars used to manufacture an embodiment of a female connector of the present invention.  
       FIG. 17  shows injection molding equipment that can be used to manufacture an embodiment of a connector of the present invention, including a female load bar and the bottom half of a mold for forming a plug body.  
       FIG. 18  shows injection molding equipment that can be used to manufacture an embodiment of a connector of the present invention, including a female load bar and the bottom half of a mold for forming a plug body wherein the cable, or wire, is in place and connected to the female load bar.  
       FIG. 19  shows injection molding equipment that can be used to manufacture an embodiment of a connector of the present invention, wherein the molds have been sealed and are ready for injection.  
       FIG. 20  shows a connector of the present invention in the bottom half of the injection mold used to manufacture it.  
       FIG. 21  shows a connector of the present invention attached to a load bar used in the manufacturing process. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      To facilitate the description of the invention, any reference material representing an element in one figure will represent the same element in any other figure. A preferred embodiment of the present connector assembly is described in connection with FIGS.  1  to  21 . A connector assembly of the preferred embodiment comprises a male connector  100  and a female connector  200  capable of mating with each other.  
      The male connector  100  preferably comprises at least one conductive element, such as pins  110 , held by a male plug body  120  including a gripping portion  140  and a head portion  130 . The head portion  130  includes a distal end  190 , a proximal end  191 , and a plurality of raised elements extending radially outward from the head portion  130 .  
      In the present embodiment, the raised elements comprise a D-shaped O-ring  160  and a plurality of saw-toothed raised ridges  150 . The D-shaped O-ring  160  is preferably located adjacent the distal, or forward, end of head portion  190 , and the saw-toothed raised ridges  150  are preferably located proximal to the D-shaped O-ring  160 . As shown in  FIGS. 5 and 7 , a thin wiper blade  170  is also preferably provided on the head portion  130  towards its proximal end, aft of the saw-toothed raised ridges  150 .  
      The male and female connectors  100 ,  200  of the preferred embodiment have a standard  7  pin terminal layout for 0.180 inch pins  110  and mating sockets  210 , respectively. In other embodiments more or less conductive terminals may be employed. Furthermore, in other embodiments, pin(s)  110  may be provided on the female connector  200  and socket(s)  210  may be provided on the male connector  100 . The plug bodies  120 ,  220  of the male and female connectors  100 ,  200  preferably have rounded sidewalls with lateral ribs  147 ,  247 , and are less than 1.050 inches in height. The plug bodies  120  and  220  of male and female connectors  100 ,  200  also preferably include a strain relief feature, such as a plurality of radially extending ribs  148 ,  248  located at the proximal end of the respective plug bodies, where the wire  180  enters the plug body. (See  FIG. 1 .)  
      The male and female plug bodies  120 ,  220  are preferably formed of a PVC material. However, other injection moldable plastics may also be used. Further, the male plug body  120  is preferably harder than the female body  220 . Further, it is desirable for the male plug body  120  to be made from a substantially rigid plastic while the female plug body  220  is formed from a flexible plastic. Preferably, the hardness of the male plug body  120  exceeds the hardness of the female plug body  130  by 5 or more points on the Shore A hardness scale, more preferably by 10 or more points, and even more preferably by 15 or more points. A preferred combination is a male body  120  having a hardness of approximately 90 A on the Shore A scale and a female body  220  having a hardness of approximately 75 A. Other male/female hardness combinations may be employed. It is less preferable to employ a male/female connector assembly where both plug bodies are of equal hardness exceeding 85 A on the Shore hardness scale. In such a case, the connector assembly cannot be disassembled without damaging one of the connectors.  
      The female plug body  220  may have a hardness as low as 60 A though this is less preferable than using a plastic with a hardness in the range of about 70 A to 80 A, and more preferably about 72 A to 78 A.  
      While PVC is a preferred material for both the male and female plug bodies, materials other than PVC are known in the trade and may be used with acceptable results if they can be suitably injection molded to yield plug bodies in the hardness ranges noted above.  
      The female connector  200  comprises at least one mating conductive terminal, such as sockets  210 , and a female plug body  220  including a receiving portion  230  and a gripping portion  240 . The receiving portion  230  of the female plug body  220  is adapted to receive the head portion  130  of the male connector  100  and includes a plurality of recessed areas adapted to interlock with the raised elements of the head portion of the male connector. Thus, where the head portion  130  of the male connector  100  has a D-shaped O-ring  160 , a plurality of saw-toothed raised ridges  150 , then the receiving portion  230  of the female connector  200  preferably will include recessed portions  250 ,  260  designed to removably interlock with the D-shaped O-ring and saw-toothed raised ridges of the head portion.  
      The receiving portion  230  preferably does not have a preformed recess to accept the male body&#39;s thin wiper blade  170 . As noted, the male body  120  is preferably made of a harder material than the female body  220 . Thus, when the male body  120  is brought into mating engagement with the female body  220 , the thin wiper blade  170  presses into the interior of the receiving portion  230  of the female body. This engagement between the wiper blade  170  of the male connector and the interior of the female connector helps create a seal that protects the connection from the elements.  
      In the preferred embodiment, the male and female connectors  100 ,  200  can be brought into mating engagement without excessive force but, after they are engaged, are semi permanently attached in that they are very difficult to separate. In addition, the conductive terminals held by the male and female connector bodies are well sealed and protected against the elements. The male and female connectors  100 ,  200  may, however, still be separated without damaging the connectors. Further, the male and female plug bodies  120 ,  220  are preferably configured to accept a clamp though a clamp is not necessary to create a semi-permanent, well-sealed connection with the connector assembly of the present invention. When a clamp is applied, however, the connector becomes nearly inseparable until the clamp is removed. In addition, the clamp helps cause the wiper blade to bite into the receiving portion, increasing the effectiveness of the connection and increasing the ability of the connector to resist permeation of the elements. A clamp such as a Phillips Industries HW-14 clamp can be used in connection with the described embodiment of the present invention.  
      Turning now to the manufacturing aspects of the present invention (see  FIGS. 16-21 ), preferably the head portion  130  and the gripping portion  140  of the male plug body  120  are integrally formed in an injection molding process. Similarly, the receiving portion  230  and the gripping portion  240  of the female plug body  220  are also preferably integrally formed in an injection molding process.  
      An Autojector 35-ton vertical C-clamp injection molding machine may be used to form the male and female plug bodies  120 ,  220 . The Autojector is preferably provided with a shuttle table. The injection material preferably is placed in the hopper. It is preferable to set the temperature zones on the Autojector machine as follows: zone one, or the rear zone, is set at 325 degrees Fahrenheit, zone two, or the barrel zone, is set to 325 degrees Fahrenheit and zone three, or the nozzle zone, is set to 375 degrees Fahrenheit.  
      The mold can be made out of hardened A2 tool steel heat treated to have a hardness of approximately RC65. The mold is comprised of a bottom mold base and a top mold base. The bases preferably hold a modular mold comprising a cavity section for forming the plug body, a strain relief section for forming the radial ribs, and a wire rail section. This mold accepts a load bar that slides in and out of the mold assembly.  
      The process preferably begins by loading the terminals onto the load bar in a predetermined position based on the print load configuration. Then the load bar preferably is placed into the mold cavity. The wires are preferably twisted and arranged from touching the walls of the mold cavity and pushed tightly onto the load bar terminals pins. Preferably, a bonding material, preferably Weldon 2001, is then applied to the cable jacket area where it is in contact with the wire rail.  
      After the mold has closed, the machine injects the molten material. The primary injection should preferably last approximately 5 seconds, after which a secondary injection pressure preferably is applied for approximately 20 seconds. After this is completed, the mold should cool preferably approximately 10 seconds before it is opened. The mold bottom is then preferably set aside to continue cooling while the same mold top closes on another mold bottom. After this, the load bar and molded connector are removed from the mold to continue cooling for three more cycles, after which the load bar is separated from the connector.  
      In a preferred embodiment, the gripping portions  140 ,  240  of both the male and female plug bodies  120 ,  220  have flat top  145 ,  245  and bottom  146 ,  246  portions and curved sidewalls  141 ,  241 . Preferably, the curved&#39;sidewalls  141 ,  241  have lateral, or longitudinal, ribs along their side  147 ,  247 . It is believed that the lateral ribs play a beneficial role in the manufacturing process in that they tend to channel the molding material as it is injected into the mold. It is believed that this channeling effect helps create a buffer which helps prevent the internal wires of the connector from migrating towards the edges of the mold during the injection molding process. Thus, the lateral ribs are believed to play a beneficial role in allowing a connector having a reduced form factor such as the connector of the present invention. Twisting the wires  180 ,  280  before molding also helps keep them from migrating during molding.  
      Where a connector of the present invention has lateral ribs and is formed through injection molding, it is beneficial to have the injection point  190 ,  290  for the mold be between two ribs along the centerline of the connector  100 ,  200 . This tends to reduce the need for removing the nub often left from injection molding processes because to the extent that any nub is left, it is situated between the ribs and does not deleteriously effect the form factor of the connector.  
      The receiving portion  230  of the female plug body  220  can be formed by using a female load bar head  300 . The load bar head  300  for forming the receiving portion  230  of the described embodiment preferably has-protrusions for mating with and holding in place the conductive terminals for the female connector (see  FIGS. 16-21 ), a distal end  390 , a proximal end  391 , a D-shaped O-Ring  360 , and 3 saw-tooth shaped ridges  350 . When manufacturing the female connector, it may be beneficial to remove the load bar before the part has cooled completely. Once the part has completely cooled, it may become difficult to separate from the load bar.  
      The load bar for forming a female connector of a preferred embodiment having seven 0.180 inch pins in a standard layout preferably is configured as shown in  FIGS. 13-16  and preferably has the following dimensions:  
      Length of head portion: 0.765 inches.  
      Distance from distal end to beginning of D-Shaped O-Ring: 0.109 inches.  
      Distance from distal end to end of D-Shaped O-Ring: 0.203 inches.  
      Distance from distal end to beginning of first saw-toothed ridge: 0.343 inches.  
      Distance from distal end to end of third saw-toothed ridge: 0.531 inches.  
      Interior radius: 0.41 inches.  
      Height of the D-shaped O-Ring: 0.065 inches.  
      Height of the saw-toothed ridges: 0.055 inches.  
      The male connector of this embodiment shall be preferably configured in a similar manner so that the male and female connectors can be brought into mating engagement.  
      Having described the present invention by reference to certain of its preferred embodiments, it is respectfully submitted that the embodiments described are illustrative rather than limiting in nature and that many variations and modifications are possible within the scope of the present invention. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments.