Patent Publication Number: US-7896715-B2

Title: Crimping terminal having a contact plate strip

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is on the basis of Japanese Patent Application No. 2008-314001, the contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a crimping terminal in which a contact plate is interposed in an inside of a pair of crimping pieces corresponding to aluminum electric wire or the like. 
     2. Description of the Related Art 
       FIG. 10  shows an embodiment of a conventional crimping terminal (See Patent Document 1). 
     A crimping terminal  61  respectively has a male tab at a tip end thereof (not shown) and a tubular electric wire crimping part  62  at a base end thereof. An aluminum electric wire (covered electric wire of which core wire is made of aluminum or aluminum alloy)  64  is crimped at the electric wire crimping part  62 . Flange-shaped swaged parts  63  are projected from right and left sides of the crimping terminal  61 . 
       FIG. 11  shows another embodiment of the conventional crimping terminal (See Patent Document 2). 
     A crimping terminal  65  is used for crimping a cable  66  which is a battery charger cable of a vehicle. The crimping terminal  65  includes a strip  68  raised from a bottom plate  67 , and a crimping part  69 . A covered electric wire  66  is inserted into the crimping part  69 , and the strip  68  is inserted into core wires of the covered electric wire  66 . Then, the crimping part  69  is crimped. Thus, it is unnecessary to strip the covered electric wire  66 . An embodiment in which a pin instead of the strip  68  is inserted is described in Patent Document 3. 
       FIG. 12  shows the other embodiment of the conventional crimping terminal (See Patent Document 4). 
     A crimping terminal  70  includes a crimping part  71  and a level strip  72  disposed at middle in a height direction in the crimping part  71  and integrated with the crimping part  71 . Serrations (a plurality of grooves)  73 ,  74  are formed on front and rear surfaces of the strip  72  and on an inner wall of the crimping part  71 . Respective core wires of two covered electric wires (not shown) are inserted into parts above and below the strip  72 , and crimped at the crimping part  71 . Then, serrations  72 ,  73  cut into the core wires to remove oxide films of the core wires. 
     [Patent Document 1] Japanese Published Patent Application No. 2007-73491 (FIG. 4) 
     [Patent Document 2] Japanese Published Utility Model Application No. S50-52490 (FIG. 2) 
     [Patent Document 3] Japanese Published Patent Application No. S62-147669 (FIG. 1) 
     [Patent Document 4] Japanese Published Patent Application No. H05-152011 (FIG. 8) 
     However, in the conventional crimping terminal shown in  FIG. 12 , for example, when a single aluminum electric wire is crimped, it is difficult to separate the core wires equally into upper and lower sides of the strip  72 , and there is a fear that a gap may be generated between the crimping part  71  and the core wires, or between the strip  72  and the core wires, thereby crimping connectivity may be reduced. The same is true in copper electric wire case instead of the aluminum electric wire. Recently, the demand for the aluminum electric wire has been increasing for weight saving of a wiring harness. 
     Accordingly, an object of the present invention is to provide a crimping terminal capable of increasing crimping connectivity by separating smoothly exposed core wires of electric wire into upper and lower sides of a strip which is interposed in a crimping part. 
     SUMMARY OF THE INVENTION 
     In order to attain the object, according to the present invention, there is provided a crimping terminal having a pair of core wire crimping pieces raised up from a bottom plate, wherein a contact strip is interposed between the pair of core wire crimping pieces via a gap for inserting core wires, and wherein the contact strip has a sloped wall or a curved wall for guiding the core wires from the gap toward the bottom plate. 
     According to the above structure, when the core wires are inserted into between the pair of core wire crimping pieces from above, respective core wires are guided downward along the sloped wall or the curved wall of the contact strip, and packed without any gap between the contact strip and the bottom plate. Thereby, when the electric wire is crimped (the pair of core wire crimping piece is crimped), a gap between the contact strip and the bottom plate is not generated, and the core wires closely contact the contact strip, the bottom plate, and the pair of core wire crimping pieces. Therefore, the core wires electrically contact with a wide contact area. The core wires of the electric wire can be inserted into between the pair of core wire crimping pieces not only from above, but also in a longitudinal direction of the crimping terminal. 
     When inserting the core wires, even if a gap is generated between the contact strip and the bottom plate, the core wires electrically closely contact the contact strip, the bottom plate, and the pair of core wire crimping pieces with a wide contact area by means of pressing downward the core wires at an upper side of the contact strip, and crimping the core wires while guiding the core wires along the sloped wall or the curved wall of the contact strip. 
     Preferably, the contact strip is formed in a flat shape, and has the sloped walls at both left and right sides thereof. 
     According to the above structure, the core wires smoothly fall down from gaps at both sides along the sloped walls at both left and right sides of the flat contact strip toward the bottom plate. 
     Preferably, the contact strip is formed in an arc sectional shape, and has the curved walls at both left and right sides thereof. 
     According to the above structure, the core wires smoothly fall down from gaps at both sides along the curved walls at both left and right sides of the arc sectional shaped contact strip toward the bottom plate. Preferably, the contact strip is composed of the curved walls at both left and right sides of the contact strip and an upper curved wall, however, the contact strip may be composed of an upper flat wall and the curved walls at both left and right sides of the flat wall. 
     Preferably, the contact strip is formed in an inverted V sectional shape, and has the sloped walls at both left and right sides thereof. 
     According to the above structure, the core wires smoothly fall down from gaps at both sides along the sloped walls at both left and right sides of the inverted V sectional shaped contact strip toward the bottom plate. Preferably, the contact strip has an inverted V sectional shape, however, the contact strip may have a trapezoidal shape. 
     Preferably, the contact strips are arranged two-tiered. 
     According to the above structure, two contact strips increase the contact area with the core wires, and in particular, when using a fat electric wire, or a plurality of electric wires, the crimped wires electrically closely contact the crimping terminal. 
     Preferably, a serration is formed on the contact strip. 
     According to the above structure, when crimping the electric wire, the serration of the contact strip, namely, a plurality of grooves and through holes with sharp edges contact the core wires, so that the oxide films of the core wires are removed, and the core wires further electrically closely contact the contact strip. Preferably, the serrations are formed on either upper and lower surfaces, or an upper surface of the contact strip. 
     These and other objects, features, and advantages of the present invention will become more apparent upon reading of the following detailed description along with the accompanied drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view showing an embodiment of a crimping terminal according to the present invention; 
         FIG. 1B  is a sectional view taken on line A-A of  FIG. 1A ; 
         FIG. 2A  is a perspective view showing a crimped electric wire with the crimping terminal; 
         FIG. 2B  is a sectional view taken on line B-B of  FIG. 2A ; 
         FIG. 3A  is a perspective view partially showing another embodiment of the crimping terminal according to the present invention; 
         FIG. 3B  is a sectional view taken on line C-C of  FIG. 3A ; 
         FIG. 4  is a perspective view partially showing the other embodiment of the crimping terminal according to the present invention; 
         FIG. 5  is a perspective view partially showing the other embodiment of the crimping terminal according to the present invention; 
         FIG. 6  is a sectional view showing the other embodiment of the crimping terminal according to the present invention; 
         FIG. 7A  is a perspective view showing the other embodiment of the crimping terminal according to the present invention; 
         FIG. 7B  is an enlarged perspective view partially showing the crimping terminal of  FIG. 7A ; 
         FIG. 7C  is a sectional view taken on line D-D of  FIG. 7A ; 
         FIG. 8  is an enlarged perspective view partially showing the other embodiment of the crimping terminal according to the present invention; 
         FIG. 9  is a sectional view showing the crimped electric wire with the crimping terminal according to the present invention; 
         FIG. 10  is a sectional view showing an embodiment of a conventional crimping terminal; 
         FIG. 11  is a lateral sectional view showing another embodiment of the conventional crimping terminal; and 
         FIG. 12  is a perspective view showing the other embodiment of the conventional crimping terminal. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 2  show an embodiment of a crimping terminal according to the present invention. 
     As shown in  FIG. 1A , a crimping terminal  1  has a flat circular electric contact part  2  at a front half thereof, and an electric wire crimping part  3  at a rear half thereof. A contact strip  6  is integrally formed with the electric contact part  2 , projected backward from the electric contact part  2 , and interposed between a pair of core wire crimping pieces  4  disposed at a front side of the electric wire crimping part  3 . Left and right sloped walls  7  are formed at left and right ends, and a rear sloped wall  8  is formed at a rear end, of the contact strip  6 . 
     The electric contact part  2  is made of two circular plates  9  overlapped with each other. The circular plates  9  are connected to each other by welding or by a hinge (not shown) disposed at a front end or a side end of the circular plate  9 . A step  10  is extended upward from a rear end of an upper circular plate  9 . The contact strip  6  is horizontally projected backward from the step  10 . 
     As shown in  FIG. 1B , the contact strip  6  is interposed between the pair of core wire crimping pieces  4  at middle thereof in a height direction, and a gap  11  is generated between the contact strip  6  and an inner wall  4   a  of the core wire crimping piece  4 . A slope angle θ of each of the left and right sloped walls  7  of the contact strip  6  is about 45 degree or less. An upper end  7   a  of each of the sloped walls  7  intersects with an upper wall  6   a  of the contact strip  6  with an obtuse angle, and a lower end  7   b  of each of the left and right sloped walls  7  intersects with a lower wall  6   b  of the contact strip  6  with an acute angle. 
     As shown in  FIGS. 1A and 1B , a slope angle of the sloped wall  8  at the rear end of the contact strip  6  is substantially the same as the sloped angle of the sloped walls  7 . When an aluminum electric wire  12  ( FIG. 2 ) is inserted horizontally into the electric wire crimping part  3 , the sloped wall  8  smoothly and surely separates the core wires  13  of the aluminum electric wire  12  into upper and lower sides. 
     When the aluminum electric wire  12  is inserted downward from above into the electric wire crimping part  3 , the left and right sloped walls  7  smoothly separates core wires  13  into left and right sides, and allows the core wires to smoothly and surely fall down toward the lower side of the contact strip  6 , namely, toward a gap  16  generated between a curved bottom plate  15  of the electric wire crimping part  3  and the horizontal contact strip  6 . 
     A pair of covered wire crimping pieces  5  is arranged higher than the core wire crimping pieces  4  at a rear side of the core wire crimping pieces  4 . A rear end  8   a  of the contact strip  6  is arranged a little forward of a rear end of the core wire crimping pieces  4 . The contact strip  6  is interposed between the core wire crimping pieces  4 . The gaps  11  are respectively generated between left and right lower ends  7   b  of the contact strip  6  and the inner wall  4   a  of the core wire crimping pieces  4  for separating the core wires  13  of the aluminum electric wire  12 , and allowing the core wires to fall down.  FIG. 1A  shows one of the core wire crimping pieces  4  which is partially cut. 
     As shown in  FIGS. 2A and 2B , when the aluminum electric wire  12  is crimped at the electric wire crimping part  3 , simultaneously, each core wire  13   a  is packed without a gap at the lower side of the contact strip  6 , namely, between the contact strip  6  and the bottom plate  15 . While upper ends  4   b  of the core wire crimping pieces  4  are curved inward in glasses shape, the core wires  13  pressed downward by the core wire crimping pieces  4  are smoothly inserted into the lower side of the contact strip  6  along the left and right sloped walls  7  of the contact strip  6 , and crimped firmly between the bottom plate  15  and the contact strip  6 . The core wires  13  on the upper wall  6   a  of the contact strip  6  are crimped between tip ends  4   c  of the core wire crimping pieces  4  and the contact strip  6 . 
     Thus, the core wires  13  contact the electric wire crimping part  3  with a large contact area. Because each of the left and right lower ends  7   b  of the left and right sloped walls  7 , and the rear end  8   a  of the rear sloped wall  8  is in a sharp edge shape, when the core wires  13  strongly contact (slidingly contact) the left and right lower ends  7   b  and the rear end  8   a , the oxide films of the core wires  13  are removed, and the core wires  13  surely electrically contact the crimping terminal  1 . 
     In a case that a fat electric wire of which core wire having a large diameter is crimped, or two electric wires are crimped, a ratio of a sectional area of the core wires  13  to a contact area between the core wires  13  and the core wire crimping pieces  4  is relatively large, further, the core wires  13  relatively slide little on each other. Therefore, contact reliability between the core wires  13  and the core wire crimping pieces  4  is reduced. However, because the contact area with the core wires  13  is increased by means of the contact strip  6 , the contact reliability is increased. 
     The aluminum electric wire  12  is crimped between an upper crimper and a lower anvil using a crimping machine (not shown). The crimper has a terminal pressing wall in a substantially heart shape, and the anvil has an arc-shaped terminal receiving wall. The crimping machine may be operated automatically or manually. A handy type nipper-shaped crimping machine can also be used. 
       FIGS. 3A to 6  show the other embodiments of the crimping terminal. Components including the same functions as those in  FIGS. 1A to 2B  are given the same reference numbers, and detailed explanation is omitted. 
     While the contact strip  6  of  FIG. 1  is flat, a contact strip  22  of a crimping terminal  21  is curved in an arc sectional shape (upward concave). The core wires  13  of the aluminum electric wire  12  (See  FIG. 2A ) at the upper side of the contact strip  22  smoothly fall down along an upper curved wall  22   a  of the contact strip  22 , and are separated into upper and lower sides. 
     The contact strip  22  may be projected backward from the electric contact part  2  like the embodiment shown in  FIG. 1 . In  FIG. 3A , a support wall  23  is extended vertically in an L shape from the bottom plate  15 , which is lower than the core wire crimping pieces  4 . Then, the contact strip  22  is folded upward from a horizontal plate  23   a  of the support wall  23 , extended backward from the support wall  23 , and interposed between the pair of core wire crimping pieces  4 . 
     Preferably, a sloped wall  24  is formed at a rear end of the contact strip  22  like the embodiment shown in  FIG. 1 . As shown in  FIG. 3B , gaps  11  for allowing the core wires  13  of the aluminum electric wire  12  ( FIG. 2 ) to smoothly fall down are formed between the left and right ends of the contact strip  22  and the inner wall  4   a  of the pair of core wire crimping pieces  4 . 
     The core wires  13  are separated into left and right sides along the left and right upper curved walls  22   a , smoothly and equally fall down, and are interposed between the contact strip  22  and the bottom plate  15  (gap  16 ). Like the embodiment shown in  FIG. 2B , when crimping the aluminum electric wire  12 , the core wires  13  positioned at a top of the contact strip  22  is pressed downward along the upper curved wall  22   a  of the contact strip  22 , and packed without a gap in between the lower curved wall  22   b  and the bottom plate  15 . 
     In  FIG. 3B , if a curvature radius of the contact strip  22  is large, sloped walls  25  may be formed at left and right side of the curved contact strip  22  like the embodiment shown in  FIG. 1 . The tip end  25   a  of the sloped wall  25  wall  25  is an edge for biting the core wires  13  and removing the oxide films from the surfaces of the core wires  13 . 
     In  FIG. 3A , reference number  24  denotes a sloped wall at the rear end, and reference number  5  denotes a covered wire crimping piece. Like the embodiment shown in  FIG. 1 , the shape of the electric contact part  2  is not limited to a circular plate, and may be tabular shape, or a male type (box shape, or tubular shape). 
     A crimping terminal  28  in  FIG. 4  is an example of changing the shape of the crimping terminal  21  of  FIG. 3 . A support wall  29  is extended vertically from the bottom plate  15  as high as the core wire crimping pieces  4 . A folded part  29   a  is folded downward from the support wall  29 . A contact strip  22  having an arc sectional shape is extended from a bottom end of the folded part  29   a . Because no interfering object exists at a bottom side of the contact strip  22 , when crimping the aluminum electric wire  12 , the contact strip  22  is moved freely in the electric wire crimping part  3  to speed up the packing of the core wires  13  ( FIG. 2 ) in the bottom side of the contact strip  22 . Components including the same functions as those in  FIG. 3  are given the same reference numbers in  FIG. 4 , and detailed explanation is omitted. 
     A crimping terminal  30  in  FIG. 5  is an example of changing the shape of the crimping terminal  28  of  FIG. 4 . In the crimping terminal  30 , two contact strips  22  each having the arc sectional shape are disposed up and down and parallel to each other inside the electric wire crimping part  3 . A higher supporting wall  31  is formed at one side of the bottom plate  15 , and a lower supporting wall  32  is formed at the other side of the bottom plate  15 . The contact strip  22  is projected from each folded part  31   a ,  32   a  extending from each supporting wall  31 ,  32 . Components including the same functions as those in  FIG. 4  are given the same reference numbers in  FIG. 5 , and detailed explanation is omitted. 
     The contact area with respect to the core wires  13  of the aluminum electric wire  12  ( FIG. 2 ) is increased by means of the upper and lower contact strips  22 . Incidentally, the flat contact strip  6  according to the embodiment of  FIG. 1  may be disposed up and down similar to the embodiment of  FIG. 5 . 
     In a crimping terminal  35  of  FIG. 6 , a shape of a contact strip  36  is neither flat nor arc sectional, but inverted V sectional. The contact strip  36  is composed of a pair of sloped plates  37 . Each sloped plate  37  includes upper and lower sloped walls  36   a ,  36   b.    
     Gaps  11  are formed between the left and right ends of the contact strip  36  and an inner wall  4   a  of the core wire crimping pieces  4  for allowing the core wires  13  ( FIG. 2 ) to smoothly fall down along the inverted V sectional shaped contact strip  36 . A slope angle of the inverted V sectional shaped contact strip  36  can be sharper than that of the arc sectional shaped contact strip  22  ( FIG. 3 ). Thus, the gaps  11  at both left and right sides become wider. If the sectional area of the contact strip  36  is the same as the contact strip  22  ( FIG. 3 ), the contact area of the core wires  13  with respect to the contact strip  36  is greater than that with respect to the contact strip  22 . 
     Similar to the embodiments of  FIGS. 1 to 5 , when crimping the crimping terminal  35 , the core wires  13  disposed at the upper side of the contact strip  36  are pressed downward along the upper sloped wall  36   a  of the contact strip  36 , and packed between the lower sloped wall  36   b  of the contact strip  36  and the bottom plate  15  (a space  16 ) without a gap. 
     Incidentally, in  FIG. 6 , the shape of the contact strip  36  may be trapezoidal (a horizontal flat plate with sloped plates  37 ) instead of inverted V sectional. Further, similar to the embodiment of  FIG. 5 , two contact strips  36  may be disposed up and down. 
       FIGS. 7 to 9  show embodiments in which a serration (a plurality of grooves) is formed on both upper and lower walls of the contact strips  22 ,  26  of the crimping terminals  21 ,  35 . Figures showing embodiments of the serration formed on the flat contact strip  6  of  FIG. 1 , and of the serration formed on the two contact strips  22  of  FIG. 5  are omitted. 
     In a crimping terminal  41  shown in  FIGS. 7A to 7C , serrations  40  are formed on both front and rear sides of the arc sectional shaped contact strip  22 ′. Grooves  40  are arranged in a width (transverse) direction of the contact strip  22 ′. Preferably, the serrations on the front and rear sides are arranged alternately. 
     The groove  40  at the rear side ( FIG. 7C ) may be omitted. A long hole (not shown) may be used instead of the groove  40  in the serration. In any case, each end of the groove (hole)  40  has a sharp edge  40   a . When crimping, the edge  40   a  removes the oxide film from the core wires  13  of the aluminum electric wire  12  ( FIG. 2 ) while the edge  40  slidingly contacts the core wires  13 . 
     An embodiment shown in  FIG. 1A  corresponds to the embodiment of  FIG. 1 . The contact strip  22 ′ is projected via a step  10  from the circular electric contact part  2 . The shape of the contact strip  22 ′ may be any one of those of  FIGS. 3A to 5 . As shown in  FIG. 7C , the serration  42  is formed on the bottom plate  15  of the electric wire crimping part  3  facing the contact strip  22 ′. 
     As shown in  FIG. 8 , a serration  43  may be formed on both front and rear sides of the inverted V sectional shaped contact strip  36  of  FIG. 6  instead of the arc sectional shaped contact strip  22 ′. Similar to the contact strip  22 ′ of  FIG. 7 , the contact strip  36 ′ of  FIG. 8  is projected via the step  10  from the circular electric contact part  2  ( FIG. 7 ). 
     As shown in  FIG. 9 , when crimping, top ends  4   b  of the core wire crimping pieces  4  bend inward and press the core wires  13  downward, and the core wires  13  are moved downward along the curved walls  22   a  of the contact strip  22 ′ or the sloped walls  36   a  of the contact strip  36 ′ ( FIG. 8 ) and packed between the bottom plate  15  and the contact strip  22 ′ or  36 ′. At the same time, edges  40   a ,  43   a  of the serration  40 ,  43  of the contact strip  22 ′,  36 ′ remove the oxide films of the core wires  13 , and the electrical contact between the core wires  13  and the contact strip  22 ′  36 ′ is improved. Similarly, the serration  42  of the bottom plate  15  removes the oxide films of the core wires  13  disposed along the bottom plate  15 . 
     Incidentally, in the above embodiments, the aluminum electric wire  12  is used. However, even when using a copper electric wire instead of the aluminum electric wire  12 , the electrical contact can be improved because the contact area of the core wires  13  is increased owing to the contact strip  6 ,  22 ,  36 . 
     Further, a crimping terminal of this invention may include at least the pair of core wire crimping pieces  4  (for example, a joint terminal), therefore, the electric contact part  2  and the covered wire crimping pieces  5  are not necessary according to the present invention. 
     Further, the configurations of the above embodiments can be used in an electric wire crimping structure of the crimping terminal, a method for crimping an electric wire, and a method for setting an electric wire other than the crimping terminal. 
     Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention hereinafter defined, they should be construed as being included therein.