Patent Publication Number: US-6341977-B1

Title: Pressure-contact terminal

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pressure-contact terminal formed with pressure-contact blades between which an end of an electric wire is press-fitted. 
     2. Description of the Related Art 
     Conventionally, there is a known pressure-contact terminal  1  as a pressure-contact terminal of this type as disclosed in U.S. Pat. No. 4,940,425 as shown in FIG.  1 . As shown in FIG. 1, the pressure-contact terminal  1  is formed at its front end side with a contact portion  2  for connection to an opposed terminal and at its the other side with an electric wire connecting portion  3  for retaining an electric wire and for connection to the electric wire. The electric wire connecting portion  3  is formed with pressure-contact portions  6 ,  7 ,  8 , and  9  hammered inward to bulge from a pair of side walls  4  and  5 . The electric wire connecting portion  3  is formed at its rear end portion with a pair of electric wire retaining chips  10  and  11 . 
     By the pressure-contact terminal  1  with such a structure, by press-fitting a covered electric wire in the electric wire connecting portion  3 , the pressure-contact portions  6 ,  7 ,  8 , and  9  cut the cover to bring an exposed core into contact with the pressure-contact portions  6 ,  7 ,  8 , and  9 , thereby establishing connection. 
     In the above-described pressure-contact terminal  1 , the pressure-contact portions  6 ,  7 ,  8 , and  9  to be connected to the electric wire and to retain the electric wire have shapes formed by hammering the side plates  4  and  5  inward and bending tip end portions (tip end portions in bulging directions). Therefore, axial retaining force of the pressure-contact portions  6 ,  7 ,  8 , and  9  is small if load is applied in an axial direction to the electric wire connected to the pressure-contact terminal  1 . 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide a pressure-contact terminal that can reliably retain an electric wire against attraction in an axial direction of the electric wire. 
     The present invention has been achieved with such points in mind. 
     According to a first aspect of the present invention, there is provided a pressure-contact terminal comprising: a contact portion to be in contact with an opposed terminal and formed on a tip end side of the pressure-contact terminal; and an electric wire connecting portion formed on a rear end side of the pressure-contact terminal, the electric wire connecting portion having a bottom plate and a pair of side plates formed by bending from both sides of the bottom plate in the same direction, the pair of side plates being formed with a plurality of pairs of pressure-contact portions; wherein at least a pair of pressure-contact portions out of the plurality of pairs of the pressure-contact portions has a pair of pressure-contact blades; and each of the pair of pressure-contact blades includes: a pressure-contact blade main body cut and bent up from the side plates; a blade portion formed on an outer periphery of the pressure-contact blade main body to cut a cover portion of a covered electric wire; a contact portion continuously formed from the blade portion to be in contact with a core of the covered electric wire; and a core retaining portion for retaining the core, the core retaining portion being formed on a lower portion side of the contact portion so as to project in such a direction as to approach to the other one of the pair of pressure-contact blades and to be brought into contact with the cover portion of the covered electric wire, thereby preventing coming off of the covered electric wire from the pressure-contact portions. 
     In this pressure-contact terminal, the covered electric wire is placed on the electric wire connecting portion and is pressed-fitted between the pressure-contact blades by using a pressure-contact jig or the like. If the covered electric wire is press-fitted between the pressure-contact blades, the cover portion of the covered electric wire is cut by the blade portions and the exposed core comes in contact with the contact portions. As a result, the covered electric wire is electrically connected to the pressure-contact terminal. In this case, end faces of the cut cover portion come in contact with the pressure-contact blade main bodies and with the core retaining portions formed on the pair of pressure-contact blades of at one of the plurality of pairs of pressure-contact portions. Thus, the covered electric wire can be reliably retained against attraction in an axial direction of the electric wire. 
     According a second aspect of the invention as it depends from the first aspect, in addition to an arrangement of the first aspect, there is provided a pressure-contact terminal, wherein the core retaining portions have retaining contact portions to come in contact with the core to be connected in a conductive manner to the core. 
     In this pressure-contact terminal, in addition to the operation of the first aspect, because the core of the covered electric wire comes in contact with the retaining contact portions, the electric connection between the covered electric wire and the pressure-contact terminal can be established. 
     According to a third aspect of the invention as it depends from the first or the second aspect, in addition to arrangements of the first and second aspects, there is provided a pressure-contact terminal, wherein the other pair of pressure-contact portions which have not the pressure-contact blades are formed in such a manner that the pair of side plates are projected inward each other by hammering operations. 
     In this pressure-contact terminal, in addition to the operation of the first and second aspects, the electric wire can be reliably retained by using the pressure-contact portions formed by hammering. In other words, although the pressure-contact portions formed by hammering the opposite side plates to project inward have small retaining force against the attraction in the axial direction of the covered electric wire, the electric wire can be retained reliably against the attraction in the axial direction of the electric wire because the core retaining portion is formed on the pressure-contact blade of at least one pressure-contact portion. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view showing a prior-art pressure-contact terminal; 
     FIG. 2 is a perspective view of an embodiment of a pressure-contact terminal according to the present invention; 
     FIG. 3 is a sectional perspective view of the pressure-contact terminal of the embodiment; 
     FIG. 4 is a plan view of a pressure-contact terminal of the embodiment; 
     FIG. 5 is a partially cutaway perspective view of the pressure-contact terminal of the embodiment; 
     FIG. 6 is a sectional view showing a state in which a covered electric wire is mounted to the pressure-contact terminal of the embodiment; and 
     FIG. 7 is a sectional perspective view of a modification of the embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     There will be detailed below the preferred embodiments of the present invention with reference to the accompanying drawings. Like members are designated by like reference characters. 
     FIG. 2 is a perspective view of the pressure-contact terminal  20  of the present embodiment, FIG. 3 is a sectional perspective view of the pressure-contact terminal  20  that is cut away at a center in a width direction, and FIG. 4 is a plan view of the pressure-contact terminal  20 . As shown in FIGS. 2 to  4 , the pressure-contact terminal  20  is formed on its front end side with a contact portion  21  to be in contact with an opposed terminal and on its rear end side with an electric wire connecting portion  22 . 
     The contact portion  21  and the electric wire connecting portion  22  are formed along a common bottom plate  23 . Side plates  24  and  25  standing to be perpendicular to the bottom plate  23  are formed on opposite side edges in a width direction of the bottom plate  23 . The side plates  24  and  25  face each other in parallel to each other. 
     The contact portion  21  includes top plates  26  and  27  respectively extending from upper edges of the side plates  24  and  25 , the top plates  26  and  27  being bent such that one is placed on the other. A contact spring chip  29  extending from a front end edge of the bottom plate  23  toward a rear end side is housed and disposed in a cavity (see FIG. 3)  28  surrounded by the bottom plate  23 , the side plates  24  and  25 , and the top plates  26  and  27 . The contact spring chip  29  is curved toward the top plate  26  side and presses the opposed terminal against an inner face of the top plate  26  to establish electric connection when the opposed terminal is press-fitted from a front end side of the contact portion  21 . 
     The electric wire connecting portion  22  is formed on its rear end side with a pair of electric wire retaining chips  30  and  31 . Between the electric wire retaining chips  30 ,  31  and the contact portion  21 , three pairs of pressure-contact portions  32 ,  33 , and  34  are respectively provided. The pressure-contact portion  32  on the electric wire retaining chips  30 ,  31  side has a pair of pressure-contact blades  35  formed by cutting and bending the side plates  24  and  25  inward and the pressure-contact portions  33  and  34  are formed by hammering the side plates  24  and  25  inward. 
     As shown in FIG. 5, the pair of pressure-contact blades  35 ,  35  of the pressure-contact portion  32  include pressure-contact blade main bodies  35 A,  35 A cut and bent from the opposite side plates  24  and  25 , blade portions  35 B,  35 B formed on outer peripheries of the pressure-contact blade main bodies  35 A and  35 A to cut a cover portion  41  of a covered electric wire  40 , contact portions  35 C formed to continue from the blade portions  35 B,  35 B and to be in contact with a core  42  of the covered electric wire  40 , and core retaining portions  35 D,  35 D formed on lower portion sides of the contact portions  35 C,  35 C. 
     The blade portions  35 B and  35 B are inclined toward the bottom plate  23  to guide the covered electric wire  40  to the space between the pressure-contact blade main bodies  35 A,  35 A and to cut the cover portion  41  of the covered electric wire  40  that slides on the slopes. The contact portions  35 C,  35 C are formed along a vertical direction to come in contact with the core  42  exposed between pieces of the cover portion cut by the blade portions  35 B,  35 B, thereby establishing electric connection between the covered electric wire  40  and the pressure-contact terminal  20 . 
     The core retaining portions  35 D,  35 D are formed into substantially right-angled shapes to project in such directions as to approach each other from the pressure-contact blade main bodies  35 A,  35 A. An end face (lower portion side) of the cut cover portion  41  of the covered electric wire  40  comes in contact with the core retaining portions  35 D,  35 D. The core retaining portions  35 D,  35 D are formed on faces that continue from the contact portions  35 C,  35 C with retaining contact portions  35 E,  35 E to be in contact with and connected in a conductive manner to the core  42 . 
     Next, structures of the pressure-contact portions  33  and  34  will be described. The pressure-contact portions  33  and  34  are formed by hammering the side plates  24  and  25  inward (toward an inner side of the pressure-contact terminal) and have plan shapes of V as shown in FIG.  4 . At upper portions of tip ends of the pressure-contact portions  33  and  34  projecting toward the other side plate  24  or  25  out of the side plates  24  and  25  formed with the pressure-contact portions  33  and  34 , slits  33 A and  34 A are formed. By forming the slits  33 A and  34 A, the upper portions of the tip ends of the pressure-contact portions  33  and  34  are sharpened to form blade portions  33 B and  34 B, thereby facilitating rupturing of an insulating cover  41  of the covered electric wire  40 . Lower portion sides of the blade portions  33 B and  34 B are contact faces  33 C and  34 C. 
     Distances between the pressure-contact portions  33 ,  33  and the pressure contact portions  34 ,  34  that respectively pair up with each other are set at dimensions slightly smaller than the core  42  of the covered electric wire  40  as shown in FIG.  4 . Therefore, if the covered electric wire  40  is press-fitted between the pressure-contact portions  33  and  34 , the cover portion  41  is cut and exposed core  42  comes in contact with the contact faces  33 C and  34 C, thereby establishing electric connection between the covered electric wire and the pressure-contact terminal  20 . 
     Next, operation of the pressure-contact terminal  20  of the embodiment on the covered electric wire will be described. First, when an end of the covered electric wire  40  is press-fitted in the electric wire connecting portion  22 , an outer peripheral face of the insulating cover  41  of the covered electric wire  40  is cut by the blade portions  35 B,  35 B,  33 B, and  34 B. Then, the cover portion  41  of the covered electric wire  40  is cut and the core  42  is exposed and comes in contact with the contact portions  35 C,  35 C, and the contact faces  33 C and  34 C. FIG. 6 shows a state in which the covered electric wire  40  is connected to the electric wire connecting portion  22 . A lower face side of the core  42  of the covered electric wire  40  is supported by the core retaining portions  35 D,  35 D and the retaining contact portions  35 E,  35 E are in contact with the core  42 . In this state, opposite sides of the cut cover portion  41  are in contact with the pressure-contact blade main bodies  35 A,  35 A and the core retaining portions  35 D,  35 D as shown in FIG.  4 . 
     According to the present embodiment, because the core retaining portions  35 D,  35 D are formed on the pressure-contact blades  35 ,  35  of the pressure-contact portions  32 , it is possible to reliably retain the electric wire  40  against attraction in an axial direction of the electric wire  40 . 
     Although the other pressure-contact portions  33  and  34  are formed by hammering the opposite side plates  24  and  25 , the cut cover portion  41  of the covered electric wire  40  comes in contact with the core retaining portions  35 D,  35 D of the pressure-contact portions  32 , thereby reliably retaining the covered electric wire  40  and establishing reliable electric connection. 
     Because the retaining contact portions  35 E,  35 E are formed on the core retaining portions  35 D,  35 D, the number of contact portions with the core  42  can be increased, thereby establishing further reliable electric connection. 
     Although the embodiment has been described above, the present invention is, not limited to the embodiment and various modifications accompanying summary of the structure may be made. For example, although three pairs of pressure-contact portions are provided in the above-described embodiment, the covered electric wire can be retained reliably with a structure including two or more pairs of pressure-contact portions. 
     FIG. 7 is a sectional perspective view showing a modification of the above-described embodiment. Although the pressure-contact portions  33  and  34  are formed by hammering in the above embodiment, the pressure contact portions  36  and  37  are formed by bending the side plate  25  in the modification shown in FIG.  7 . Tip end portions of the pressure-contact portions  36  and  37  are formed as bent portions  36 A and  37 A by bending a metal plate. 
     According to the modification, because upper faces of the pressure-contact portions  36  and  37  are sections formed by cutting the side plate  25 , it is easier to capture the cover portion  41  of the covered electric wire  40 , thereby increasing retaining force in the axial direction of the covered electric wire  40 . Other structures of the modification are similar to those of the above embodiment. 
     Although the pressure-contact terminal  20  is formed by bending the sheet of metal plate in the developed shape, it is possible to form a plurality of members integrally with the pressure-contact terminal. 
     The entire contents of Japanese Patent Application P11-317373 (filed Nov. 8, 1999) are incorporated herein by reference. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. The scope of the invention is defined with reference to the following claims.