Patent Publication Number: US-6334251-B1

Title: Method of manufacturing a connecting structure for covered wires

Description:
This is a division of application Ser. No. 09/260,472, filed Mar. 2, 1999, now U.S. Pat. No. 6,046,407 all of which are incorporated-herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a connecting structure for covered wires where their respective conductors are connected to each other by oscillating respective insulating covers of the wires with ultrasonic waves. More particularly, it relates to a connecting structure which is effective to connect a shield wire with a ground wire. 
     2. Description of the Related Art 
     Generally, it is complicated and troublesome to handle a shield wire having a braided wire coaxially disposed around a core line (or core lines) with the deteriorated workability in using the shield wire. As an effective measure for improving the deteriorated workability, there is provided a connecting structure for wires which takes advantage of inside heating due to the ultrasonic oscillation by Japanese Unexamined Patent Publication (kokai) No. 7-320842. 
     In the publication, there are shown two kinds of covered wires. One is a shield wire which comprises a core line, an inside insulating rind arranged outside the core line, a braided wire as a shield conductor arranged outside the inside insulating rind, and an outside insulating rind. The other is a ground wire consisting of a core line and an outside resinous rind arranged outside the core line. 
     According to the disclosed method of connecting the braided wire of the shield wire being connected to a connector, to the core line of the ground wire being also connected to the connector, in front of the connector, the ground wire is firstly overlaid on the shield wire so as to cross each other at a connection point. Next, the overlapping portions are interposed between upper and lower resin tips. Then, while compressing the upper and lower resin tips from the outside, they are subjected to ultrasonic oscillation by making use of an ultrasonic horn and an anvil. Consequently, both of the outside rinds of the shield wire and the ground wire are molten for elimination, so that the braided wire of the shield wire comes into electrical contact with the core line of the ground wire. Simultaneously, the upper and lower resin tips are mutually welded to each other thereby to seal up the surroundings of the above connecting point. In a, in the modification, the upper and lower resin tips are provided on bearing faces, respectively thereof, with wire-accommodating shallow grooves for positioning the shield wire. 
     However, in the so-obtained connecting structure a tip of the core line of the ground wire sometimes projects from the integrated upper and lower resin tips, so that the connecting part gets larger due to the resultant protrusion, causing an obstacle to arranging the wire harness. In addition, the problem of reduction in the insulating effect arises from the projecting conductor (core line) of the ground wire. 
     SUMMARY OF THE INVENTION 
     Under such a circumstance, it is therefore an object of the present invention to provide a connecting structure for covered wires, which is capable of preventing a conductor of the covered wire from projecting from the structure. 
     The object of the present invention described above can be accomplished by a connecting structure for covered wires, comprising: 
     a first covered wire having a first conductor covered with a first resinous cover; 
     a second covered wire having a second conductor covered with a second resinous cover, the second conductor being electrically connected with the first conductor of the first covered wire cross each other; and 
     an upper resin tip and a lower resin tip between which an electrical connecting part of the first and second conductors and the surroundings are interposed, the upper resin tip being welded to the lower resin tip while interposing the first and second covered wires between the upper resin tip and the lower resin tip; 
     wherein either one of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a stopper as a projection for defining the position of a leading end of the second covered wire interposed between the upper and lower resin tips, while the other of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a recess for receiving the stopper. 
     With the above-mentioned connecting structure, since the stopper serves to define the tip of the second covered wire in position, there is no possibility that the a tip of the second conductor of the second covered wire projects from the upper and lower resin tips. Therefore, since a protrusion resulting from the projecting second conductor of the second covered wire is eliminated on the peripheral face of the welded resin tips, it is possible to provide the small-sized connecting part between the first and second covered wires, whereby the workability in arranging the wire harness can be improved. Further, with the reduction of an exposed portion of the second conductor, it is possible to improve the insulating effect of the connecting structure. 
     In the above-mentioned connecting structure, preferably, the first covered wire is a shield wire, while the second wire is a ground wire and the first conductor is a shield conductor of the shield wire, while the second conductor is a core line of the ground wire. 
     With the preferred structure, as the stopper serves to prevent the core line of the ground wire from projecting from the upper and lower resin tips, it is possible to avoid the exposure of the core line. Thus, also in this case, since a protrusion resulting from the projecting core line of the ground covered wire is eliminated on the peripheral face of the completed connecting part, it is possible to provide the small-sized connecting part between the shield wire and the ground wire, so that the workability in arranging the wire harness can be improved. 
     In the above-mentioned connecting structure, preferably, the stopper is substantially U-shaped in its plan view to form a groove for fitting the leading end of the second covered wire, the groove being defined by a pair of opposing sidewalls, and a distance between the sidewalls of the groove is smaller than a diameter of the second covered wire. 
     With the preferred connecting structure, since the leading end of the second covered wire is fitted in the groove of the stopper, it is possible to fix the second covered wire securely. Therefore, the setting operation of the ground wire can be facilitated. Furthermore, as the displacement of ground wire during the welding can be restricted owing to the provision of the stopper, it is possible to improve the electrical reliability of the connecting part. 
     In the present invention, preferably, each of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a wire receiving groove which has a semi-circular cross section having a diameter substantially equal to a diameter of the first covered wire. 
     According to the preferred connecting structure, since the diameter of the wire receiving groove is substantially equal to the diameter of the first covered wire, it is possible to weld the upper resin tip to the lower resin tip in the wrapping manner without compressing the first resinous cover of the first covered wire. Thus, since there is no possibility that the first resinous cover of the first covered wire is torn or broken by the upper or lower resin tip, the fixing force between the upper and lower resin tips and the first covered wire can be enhanced. In addition, it is possible to exclude a possibility that the first covered wire exposes the first conductor in the vicinity of the upper and lower resin tips. 
     According to the present invention, there is also provided a method of producing a connecting structure for covered wires, the method comprising the steps of: 
     preparing a first covered wire having a first conductor covered with a first resinous cover and a second covered wire having a second conductor covered with a second resinous cover; 
     overlaying the second covered wire on the first covered wire cross each other; 
     interposing respective overlapping portions of the first and second covered wires between an upper resin tip and a lower resin tip; and 
     oscillating the upper and lower resin tips with ultrasonic waves while compressing the upper and lower resin tips from the outside, whereby the first and second resinous covers of the first and second covered wires are molten for removal thereby to bring the first conductor of the first covered wire into electrical contact with the second conductor of the second covered and simultaneously, the upper and lower resin tips are mutually welded to each other thereby to seal up the surroundings of a contact between the first conductor and the second conductor; 
     wherein either one of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a stopper as a projection for defining the position of a leading end of the second covered wire interposed between the upper and lower resin tips, while the other of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a recess for receiving the stopper. 
     Also in the above-mentioned method, preferably, the first covered wire is a shield wire, while the second wire is a ground wire and the first conductor is a shield conductor of the shield wire, while the second conductor is a core line of the ground wire. 
     Also in the above-mentioned method, preferably, the stopper is substantially U-shaped in its plan view to form a groove for fitting the leading end of the second covered wire, the groove being defined by a pair of opposing sidewalls, and a distance between the sidewalls of the groove is smaller than a diameter of the second covered wire. 
     Also in the above-mentioned method, preferably, each of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a wire receiving groove which has a semi-circular cross section having a diameter substantially equal to a diameter of the first covered wire. 
     These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompany drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are views showing resin tips constituting a connecting structure in accordance with the first embodiment of the present invention, in which FIG. 1A is a perspective view showing an upper resin tip turned over and FIG. 1B is a perspective view showing a lower resin tip; 
     FIGS. 2A and 2B show the connecting structure of the first embodiment, in which FIG. 2A is a perspective view of the connecting structure and FIG. 2B is a view in the direction of an arrow II b  of FIG. 2A; 
     FIGS. 3A,  3 B and  3 C are views showing resin tips constituting the connecting structure in accordance with the second embodiment of the present invention, in which FIG. 3A is a perspective view showing an upper resin tip turned over, FIG. 3B is a perspective view showing a lower resin tip, and FIG. 3C is an enlarged plan view of a portion indicated with an arrow III c ; and 
     FIGS. 4A and 4B show the connecting structure of the second embodiment, in which FIG. 4A is a perspective view of the connecting structure and FIG. 4B is a cross sectional view of the connecting structure, taken along a line IV b —IV b  of FIG.  4 A. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     U.S. Pat. No. 5,584,122, Kato et al., issued on Dec. 17, 1996 is characterized by reference herein in its entirety. Embodiments of the present invention will be described with reference to drawings hereinafter. 
     1 st . embodiment 
     FIGS. 1A and 1B show resin tips constituting the connecting structure in accordance with the first embodiment of the present invention. FIG. 1A shows an upper resin tip  13  turned over, while FIG. 1B shows a lower resin tip  14 . 
     Each of the resin tips  13 ,  14  is constituted by a plate body having a profile of an elongated circle in its plan view. Formed on respective butt faces (i.e. mutual contact faces being welded) of the upper and lower resin tips  13 ,  14  are wire receiving grooves  13   a ,  14   a  each of which extends along a direction of the long axis of the elongated circle and has a semicircular cross section of a diameter generally equal to that of an outside rind  1   d  of the shield wire  1 . 
     According to the embodiment, the upper resin tip  13  is provided, on the butt face, with a stopper  13   b  which defines the position of a tip of the ground wire  2  when crossing the ground wire  2  on the shield wire  1 . Meanwhile, the lower resin tip  14  is provided on the butt face with a recess  14   b  for accommodating the stopper  13   b . In a modification, the stopper  13   b  may be provided on the lower resin tip  14  while forming the recess  14   b  on the upper resin tip  13 , conversely. 
     In order to connect the shield wire  1  to the ground wire  2 , it is firstly carried out to lay the ground wire  2  on the shield wire  1  so as to cross each other at a connecting part. Next, the overlapping portions of the wires  1 ,  2  are interposed between the upper resin tip  13  and the lower resin tip  14 . At this time, the tip of the ground wire  2  is butted against the stopper  13   b  in order to define the position of the tip of the wire  2 . Under such a condition, the overlapping portions of the wires  1 ,  2  are subjected to ultrasonic oscillation by making use of an ultrasonic horn  7  and an anvil (not shown) while compressing the upper and lower resin tips  13 ,  14  from the outside. Consequently, both of the outside rind  1   d  of the shield wire  1  and an outside rind  2   b  of the ground wire  2  are molten for removal, so that a braided wire  1   c  of the shield wire  1  comes into electrical contact with a core line(s)  2   a  of the ground wire  2 . Simultaneously, the upper and lower resin tips  13 ,  14  are mutually welded to each other thereby to seal up the surroundings of the above connecting point. In this way, a connecting part S 1  can be obtained between the shield wire  1  and the ground wire  2 , as shown in FIGS. 2A and 2B. 
     According to the resultant connecting structure, since the stopper  13   b  serves to define the position of the tip of the ground wire  2 , it is possible to prevent the tip of the core line  2   a  of the wire  2  from projecting from the resin tips  13 ,  14 . Thus, no protrusion resulting from the projecting core line of the ground wire  2  is formed on the peripheral face of the completed connecting part S 1 , as shown in FIG.  2 B. Consequently, with the removal of protrusion, it is possible to provide the small-sized connecting part S 1 , whereby the workability in arranging the wire harness can be improved. 
     2 nd . embodiment 
     FIGS. 3A,  3 B and  3 C show resin tips constituting the connecting structure in accordance with the second embodiment of the present invention. FIG. 3A shows an upper resin tip  23  turned over, while FIG. 3B shows a lower resin tip  24 . FIG. 3C shows an enlarged part of FIG. 3A, indicated with an arrow III c  in the figure. 
     The second embodiment is similar to the first embodiment in that both of the resin tips  23 ,  24 , alternatively referred to as resin members, are constituted by plate bodies each having a periphery of an elongated circle in its plan view and also provided on respective butt faces thereof, with wire receiving grooves  23   a ,  24   a , each of which has a diameter corresponding to the diameter of the shield wire  1 . The second embodiment differs from the first embodiment with respect to the configuration of the stopper. According to the second embodiment, on the butt face of the upper resin tip  23 , a stopper  23   b  is formed to have a substantial U-shaped configuration in plan view, providing a groove  26  for receiving the tip of the ground wire  2 . The groove  26  is composed of a front butt wall  26   a  and a pair of sidewalls  26   b ,  26   b  on both sides of the wall  26   a . As shown in FIG. 3 c , the width H between the sidewalls  26   b ,  26   b  is smaller than a diameter D of the ground wire  2 . Therefore, the tip of the ground wire  2  can be fitted between the sidewalls  26   b ,  26   b . Moreover, the lower resin tip  24  is provided, on the butt face, with a recess  24   b  for accommodating the stopper  23   b . Of course, in a modification, the stopper  23   b  may be provided on the lower resin tip  24  and the recess may be formed on the upper resin tip  23 , conversely. 
     FIGS. 4A and 4B show a connecting part S 2  between the shield wire  1  and the ground wire  2 , which can be produced by using the resin tips  23 ,  24 . According to the so-obtained structure, since the tip of the ground wire  2  is to be fitted in the groove  26  of the stopper  23   b  in advance of putting the upper and lower resin tips  23 ,  24  together, it is possible to certainly arrange and fix the tip of the ground wire  2  in position, whereby the setting operation of the ground wire  2  can be facilitated. Furthermore, as the displacement of ground wire  2  during the welding can be restricted owing to the provision of the stopper  23   b , it is possible to improve the electrical reliability of the connecting part S 2 . Additionally, since the position of the tip of the core line  2   a  of the ground wire  2  is defined by the stopper  23   b , it is possible to solve the problem of projecting the tip of the core line  2   a  from the integrated tips  23 ,  24 , as similar to the first embodiment. 
     Finally, it will be understood by those skilled in the art that the foregoing description is related to two preferred embodiments of the disclosed connecting structure, and that various changes and modifications may be made to the present invention without departing from the spirit and scope thereof.