Patent Publication Number: US-6042431-A

Title: Joint device for an automotive wiring harness

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a joint device for an automotive wiring harness and is particularly designed to increase the number of wires connectable with one bolt. 
     2. Description of the Prior Art 
     Wires forming an automotive wiring harness are grounded to a vehicle body by fastening terminals at ends of the wires to a bolt. Specifically, as shown in FIG. 3, a mount hole 51a of a prior art terminal 51 at an end of a wire 50 is fitted down on a shaft 2a of a bolt projecting from a vehicle body 1, and the terminal 51 is fastened by a nut 52. 
     The prior art terminal 51 at the end of the wire 50 is a so-called LA terminal which is provided with a substantially circular electrical contact portion 51b formed at the leading end, and a barrel portion 51c at the opposed end. A mount hole 51a is formed centrally through the circular contact portion 51b. 
     The terminals 51 enable two wires 50 to be connected with the shaft 2a of one bolt to establish a ground by putting flat surfaces of the terminals 51 together as shown in FIGS. 4(B) and 4(C). More particularly, the connection of the terminals 51 with the shaft 2a of the bolt requires the contact surface of the terminal 51 to be flattened to ensure a stable contact. On the other hand, one side of the barrel 51c of the terminal 51 inevitably has a thickness due to the diameter of the wire 50. Thus, a maximum of two wires 50 can be connected with one bolt by putting the flat surfaces of the barrel portions 51 thereof together as described above. 
     Accordingly, to ground three or more wires, it is necessary to employ a joint connector for accommodating a plurality of wires and combining them into one wire that can be mounted to a single bolt. Alternatively the number of bolts at the vehicle body can be increased so that no more than two wires can be connected with each bolt. A joint connector leads to an increased cost for parts and more bolts necessitates more connecting operations. 
     In view of the above problem, it is an object of the present invention to provide a joint device for an automotive wiring harness which increases the number of wires connectable with one bolt. 
     SUMMARY OF THE INVENTION 
     According to the invention, there is provided a joint device for an automotive wiring harness. The joint device comprises an insulation casing. A bolt having a shaft projects from the vehicle body and through a hole in the bottom wall of the insulation casing. A plurality of wire insertion slots are open to an upper wall and extend toward the bottom wall. The wire insertion slots are formed at least in a side wall of the insulation casing at predetermined or predeterminable intervals for introducing a plurality of wires thereinto. A terminal insertion opening substantially communicates with the wire insertion slots. The mount hole-provided electrical contact portions of the terminals at the ends of the wires are inserted or are insertable between the upper wall and the bottom wall of the insulation casing through the terminal insertion opening. The mount holes of the terminals are fitted or are fittable down on the bolt shaft, and the wires are inserted or are insertable into the wire insertion slots. A nut then is fastened or is fastenable to the bolt shaft with the electrical contact portions of the terminals at the ends of the plurality of wires. 
     With this construction, the bolt shaft projects from the bottom wall of the insulation casing and the plurality of wire insertion slots for permitting the insertion of the plurality of wires thereinto are provided in the side wall of the insulation casing at specified intervals. Accordingly, the electrical contact portions which are flat surfaces of the mount hole-provided cramping terminals at the ends of the wires can be put together (preferably on a terminal table) and, at the same time, the wires, which are unflat portions, can be dispersedly arranged in the respective wire insertion slots. 
     According to a preferred embodiment of the invention, the joint device further comprises a terminal table which is so mounted or mountable on the bolt shaft as to fit a through hole thereof down on the bolt shaft. The electrical contact portions are inserted or are insertable between the upper wall of the insulation casing and the terminal table through the terminal insertion opening. The joint device may further comprise a spring mounted on the bolt shaft. The terminal table may be biased in a direction to the upper wall of the insulation casing by being placed on an upper end of the spring. The nut then may be fastened to the bolt shaft with the electrical contact portions of the terminals at the ends of the plurality of wires put together on the terminal table. 
     The number of the wire insertion slots may be equal to the smaller one of an integer obtained by rounding up a quotient of the largest thickness of barrel portions of the terminals divided by the smallest thickness of electrical contact portions and the number of wires to be inserted. 
     According to a further embodiment of the invention, there is provided a joint device for an automotive wiring harness, comprising an insulation casing. A bolt having a shaft projects from a bottom wall of the insulation casing, and a spring is mounted on the bolt shaft. A terminal table is so mounted on the bolt shaft as to be biased by being placed on an upper end of the spring and by fitting a through hole thereof down on the bolt shaft. A plurality of wire insertion slots are formed in a side wall of the insulation casing at specified intervals for permitting the insertion a plurality of wires thereinto, and a terminal insertion opening communicates with the wire insertion slots. Mount hole-provided electrical contact portions of cramping terminals are secured at ends of the wires and are inserted between an upper wall of the insulation casing and the terminal table through the terminal insertion opening. The mount holes of the terminals then are fitted down on the bolt shaft, and the wires are inserted into the wire insertion slots. Finally a nut is fastened to the bolt shaft with the electrical contact portions of the cramping terminals at the ends of a plurality of wires put together on the terminal table. 
     The width of the plurality of wire insertion slots is set substantially equal to or larger than the diameter of the wires and the plurality of wires are alternately inserted or insertable into the respective wire insertion slots. 
     When the plurality of cramping terminals are put together by fitting the mount holes down on the bolt, the wire corresponding to the lower cramping terminal can be inserted into the wire insertion slot different from the one for the wire corresponding to the upper cramping terminal. Since the wires inserted into one wire insertion slot are spaced apart by the thickness of the electrical contact portion of the cramping terminal of the wire inserted into an other wire insertion slot, they do not interfere with each other. Thus, the number of wires connectable with one bolt can be increased. 
     Further, the plurality of cramping terminals are held by the nut while being pressed against the terminal table by the spring. Accordingly, the electrical contact portions of the plurality of cramping terminals fitted down on one bolt can be put together closely, thereby ensuring a high contact stability. 
     Further, since the respective wires are locked in the wire insertion slots even if a pulling force acts on the wires due to a vibration of a vehicle, the respective cramping terminals do not rotate about the bolt and a contact stability can be obtained. 
     Preferably, the terminal insertion opening is an opening formed in the upper wall of the insulation casing. This enables the cramping terminals to be easily inserted into the insulation casing obliquely from above. 
     The plurality of wires can be grounded if the bolt shaft is inserted or is insertable through a through hole formed in a vehicle body and a through hole formed in the bottom wall of the insulation casing to ground the plurality of wires. 
     If a head of the bolt is embedded in the bottom wall of the insulation casing in such a manner that the shaft thereof projects from the bottom wall, the plurality of wires can be electrically connected with each other. 
     These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1(A), 1(B) and 1(C) are an exploded perspective view, a schematic perspective view and a section showing one embodiment of the invention. 
     FIG. 2 is a section showing a modification of the embodiment of the invention. 
     FIG. 3 is a schematic diagram of a prior art. 
     FIGS. 4(A), 4(B) and 4(C) are schematic perspective views showing LA terminals. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, terminals 4b, 5b, 6b are cramping terminals provided with mount holes and are referred to as &#34;LA terminals&#34;. The terminals 4b, 5b and 6b are at ends of wires 4a, 5a, 6a forming or being part of a wiring harness. The wires 4a, 5a and 6a are accommodated in an insulation casing 3 mounted or mountable on a shaft 2a of a bolt 2 projecting from a vehicle body 1 and are grounded or fixed by a nut 7. 
     The insulation casing 3 is a substantially cylindrical casing of metal and is formed with a bolt hole 3b in the center of a bottom wall 3a. The shape of the insulation casing 3 may be adapted or corresponding substantially to that of the cramping terminals 4b, 5b, 6b. The insulation casing 3 comprises two wire insertion slots 8a, 8b which are formed or cut in a side wall 3a. The slots 8a, 8b extend downwardly from the upper end of the casing 3 and are radially spaced apart at a predetermined or predeterminable interval. A terminal insertion opening 9 is provided in an upper wall 3d. The opening 9 has a diameter larger than that of the bolt hole 3b and is substantially in communication with the bolt hole 3b and the respective wire insertion slots 8a, 8b. The width of the wire insertion slots 8a, 8b is substantially equal to or larger than the diameter of wires 4a, 5a, 6a. 
     The shaft 2a of the bolt 2 projects from the bottom wall 3b in the insulation casing 3. A spring 10 is mounted or mountable on the shaft 2a of the bolt 2, and a through hole 11a of a terminal table or plate 11 then is fitted or is fittable down on the spring 10. The terminal table 11 is mounted while being spring-biased away from the bottom wall 3b of the insulation casing 3. 
     On the other hand, the LA terminals 4b, 5b, 6b are provided with substantially circular electrical contact portions 4d, 5d, 6d formed with mount holes 4c, 5c, 6c at their leading ends. The wires 4a, 5a, 6a are connected with barrel portions 4e, 5e, 6e provided behind the electrical contact portions 4d, 5d, 6d. Although one side surface of each of the LA terminals 4b, 5b, 6b is bulging due to the thickness of the wires 4a, 5a, 6a, the other side surface thereof is substantially flat. 
     In the above insulation casing 3, the electrical contact portion 4d of the LA terminal 4b is first inserted between the upper wall 3d and the terminal table 11 through the terminal insertion opening 9. Since the terminal insertion opening 9 is open in the upper wall 3d of the insulation casing 3, the LA terminal 4b easily can be inserted obliquely from above the insulation casing 3. 
     Then, the mount hole 4c of the LA terminal 4b is fitted down on the shaft 2a of the bolt 2 and the wire 4a is inserted into the wire insertion slot 8a. 
     Next, the second LA terminal 5b is inserted in a manner similar to the above. In particular, the mount hole 5c thereof is fitted down on the shaft 2a of the bolt 2, and the wire 5a is inserted into the adjacent wire insertion slot 8b. The third LA terminal 6b is inserted in a manner similar to the above by fitting the mount hole 6c down on the shaft 2a of the bolt 2 and inserting the wire 6a into the wire insertion slot 8a as the wire 4a corresponding to the first LA terminal 4b is. 
     The electrical contact portions 4d, 5d, 6d of the respective LA terminals 4b, 5b, 6b are put together by alternately inserting the wires 4a, 5a, 6a into the respective wire insertion slots 8a, 8b. Accordingly, the wires 4a, 6a inserted into the same wire insertion slot 8a do not interfere with each other since they are spaced apart by the thickness of the electrical contact portion 5d of the LA terminal 5b of the wire 5a inserted into the wire insertion slot 8b. Thus, a plurality of wires 4a, 5a, 6a can be inserted into one wire insertion slot 8a or 8b according to the vertical dimension of the wire insertion slots 8a, 8b in relation to the diameter of the wires 4a, 5a, 6a, thereby increasing the number of wires connectable with one bolt 2. 
     The nut 7 then is fastened to the bolt 2. At this time, the spring 10 is compressed as the nut 7 is screwed down, and the electrical contact portions 4d, 5d, 6d of the three LA terminals 4b, 5b, 6b are pressed against the terminal table 11 accordingly. In this way, the three LA terminals 4b, 5b, 6b can be put closely together, ensuring a higher electric contact stability. 
     Although the terminal insertion openings 8a, 8b are provided in the upper wall 3d of the insulation casing 3 in the foregoing embodiment, they may be provided in the side wall 3c of the insulation casing 3 (8a, 8b are actually formed in the side wall 3c in this embodiment as well). In such a case, slits into which the electrical contact portions 4c, 5c, 6c of the LA terminals 4b, 5b, 6b may be so formed as to be continuous with the respective wire insertion openings. 
     The LA terminals 4b, 5b, 6b are connected with the shaft 2a of the bolt 2 projecting from the vehicle body 1 to establish a ground in the foregoing embodiment. However, a plurality of wires can be connected electrically with each other by embedding a head 2b of the bolt 2 in a bottom wall 30a of an insulation casing 30 made e.g. of a resin, thereby projecting the shaft 2a of the bolt 2 from the bottom wall 30a. Accordingly, a prior art splice connection is unnecessary. 
     As is clear from the above description, only the electrical contact portions, which are flat surfaces of the cramping terminals at the ends of the wires, can be put together on the terminal table in the insulation casing and, at the same time, the wires, which are unflat portions, can be arranged dispersedly in the respective wire insertion slots. Further, the electrical contact portions of the respective cramping terminals are put together by alternately inserting the wires into the plurality of wire insertion slots, with the result that the wires inserted into one wire insertion slot do not interfere with each other since they are spaced apart by the thickness of the electrical contact portion of the cramping terminal of the wire inserted into the other wire insertion slot. 
     Accordingly, the number of wires connectable with one bolt can be increased; a cost for parts can be reduced; and a connection operability can be improved. 
     Further, the LA terminal is held by the nut while being pressed against the terminal table by the LA terminal. Therefore, the electrical contact portions of the plurality of cramping terminals fitted down on one bolt can be engaged closely. 
     Furthermore, if the number of wire insertion slots is equal to the smaller one of an integer obtained by rounding up a quotient of the largest thickness of barrel portions of the terminals divided by the smallest thickness of electrical contact portions and the number of wires to be inserted, the wires can be arranged effectively in a minimum possible number of wire insertion slots, making the construction of the joint device simpler.