Patent Publication Number: US-8118621-B2

Title: Connection terminal

Description:
BACKGROUND 
     This invention relates to a connection terminal having a neck portion formed between a terminal connection portion and a wire connection portion. 
     Patent Document 1 discloses a conventional connection terminal. As shown in  FIGS. 8 and 9 , this conventional connection terminal  100  includes a terminal connection portion  101  for the connection of a mating terminal thereto, a wire connection portion  110  having a wire accommodating space  112  and adapted to be connected to a wire (not shown) disposed in the wire accommodating space  112 , and a neck portion  120  disposed between the terminal connection portion  101  and the wire connection portion  110 . This connection terminal  100  is formed by bending a single electrically-conductive sheet into a predetermined shape. 
     The terminal connection portion  101  includes a tubular portion  102  defined by a lower wall  102   a , opposite side walls  102   b  and an upper wall  102   c . A resilient contact piece portion  102   d  is provided within the tubular portion  102 . When the mating terminal is inserted into the tubular portion  102 , this mating terminal is held in intimate contact with the tubular portion  102  by a reaction force resulting from resilient deformation of the resilient contact piece portion  102   d . A rear edge of the upper wall  102   c  of the tubular portion  102  serves as a lance engagement portion  103 . The connection terminal  100  is accommodated in a terminal accommodating chamber of a connector housing (not shown), and a lance provided within the terminal receiving chamber is engaged with the lance engagement portion  103 , thereby fixing the connection terminal  100  relative to the connector housing. 
     The wire connection portion  110  has a surrounding wall  111  of a generally U-shaped cross-section extending continuously from a lower wall  121   a  and opposite side walls  121   b  of the neck portion  120 , and the wire accommodating space  112  is defined by this surrounding wall  111 . A pair of first wire press-fastening portions  113 , as well as a pair of second wire press-fastening portions  114 , are formed on and project respectively from upper edges of the U-shaped surrounding wall  111 . The pair of first wire press-fastening portions  113  are press-fastened onto an exposed portion of a conductor of the wire (not shown) to be fixed thereto, while the pair of second wire press-fastening portions  114  are press-fastened onto a sheath of the wire to be fixed to the wire. 
     The neck portion  120  includes the lower wall  121   a  extending continuously from the lower wall  102   a  of the terminal connection portion  101 , and the opposite side walls  121   b  extending continuously respectively from the opposite side walls  102   b  of the terminal connection portion  101 . The neck portion  120  is formed such that a width W 12  of the neck portion  120  between the opposite side walls  121   b  is decreasing gradually toward the wire connection portion  110 . 
     Namely, in order that the wire connection portion  110 , when press-fastened onto the wire, can firmly fix the wire (not shown), it is preferred that the width of the wire accommodating space  112  should be formed into a dimension corresponding to the width of the wire. Therefore, by the provision of the neck portion  120 , a width W 10  at the tubular portion  102  of the terminal connection portion  101  is reduced or narrowed down into a width W 11  at the wire connection portion  110 .
     [Patent Document] Japanese Patent Publication No. 2007-280825 A   

     However, in the case where the connection terminal  100  is designed to meet a small-diameter design of the wire (not shown), so that the difference between the width W 10  of the tubular portion  102  of the terminal connection portion  101  and the width W 11  of the wire connection portion  110  is large, the rate of gradual decrease of a width W 12  of the neck portion  120  increases, and therefore a crack or the like is liable to be produced in the connection terminal  100  by a bending force applied during a press-shaping operation for forming the connection terminal  100 , thus causing a so-called terminal crack. 
     Here, in order to prevent such terminal crack, it may be proposed to increase a length L 11  (see  FIG. 9 ) of the neck portion  120 . In this case, however, the overall length L 10  of the connection terminal  100  is increased because of the increased length of the neck portion  120 . When the connection terminal  100  is thus increased in size, there arise problems such as an increased cost of the material for the connection terminal  100 , an increased size of the connector housing for accommodating the connection terminal and an increased cost of the material for the connector housing. 
     SUMMARY 
     It is therefore one advantageous aspect of the present invention is to provide a connection terminal in which even when the connection terminal is designed to meet a small-diameter design of a wire, an overall length of the connection terminal does not need to be increased, and also a terminal crack developing during the manufacture can be prevented. 
     C1. 
     According to one aspect of the invention, there is provided a connection terminal, comprising: 
     a terminal connection portion having a tubular part surrounded by a first wall, a second wall opposing the first wall and side walls connecting the first wall and second wall, the tubular part configured to accommodate and to be electrically connected to a mating terminal; 
     a wire connection portion configured to engage a wire; 
     a neck portion disposed between the terminal connection portion and the wire connection portion and having a third wall extended from the first wall and standing walls standing on the third wall, the standing walls extended from the side walls respectively and opposing each other, a distance between the standing walls decreased according to an extending direction in which the third wall is extended from the first wall, the neck portion electrically connected to the wire connection portion; 
     wherein an end of the second wall is protruded in the extending direction than connecting parts of the side walls where the standing walls are connected. 
     The connection terminal may be configured such that the terminal connection portion, the neck portion and the wire connection portion are formed by a single sheet made of a conductive material. 
     The connection terminal may be configured such that the wire connection portion has a bent wall extended from the third wall and the standing walls and defining a space in which the wire is disposed. 
     The connection terminal may be configured such that the end of the second wall serves as a lance engagement member configured to be engaged with a lance of a connector housing. 
     The connection terminal may be configured such that: the end of the second wall is connected to the connecting parts by end edges of the side walls; and a distance between the end edges and the second wall is decreased according to the extending direction. 
     The connection terminal may be configured such that the second wall is connected to the connecting parts by end edges of the side walls which are orthogonal to the extending direction. 
     The connection terminal may be configured such that corners which connect upper faces of the standing walls opposite to the third wall and end faces of the side walls connecting the second wall to the connecting part are rounded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a first embodiment of a connection terminal according to the present invention. 
         FIG. 2  is a plan view of the connection terminal of the first embodiment. 
         FIG. 3  is a side-elevational view of the connection terminal of the first embodiment. 
         FIG. 4  is a bottom view of the connection terminal of the first embodiment. 
         FIG. 5  is an extended side-elevational view of the connection terminal of the first embodiment, in a condition where a terminal crack develops. 
         FIG. 6  is a side-elevational view of a second embodiment of a connection terminal according to the present invention. 
         FIG. 7  is an extended side-elevational view of the connection terminal of the second embodiment, in a condition where a terminal crack develops. 
         FIG. 8  is a perspective view of a conventional connection terminal. 
         FIG. 9  is a cross-sectional view of the conventional connection terminal. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS 
     Exemplified embodiments of the invention are described below in detail with reference to the accompanying drawings. 
     First Embodiment 
     As shown in  FIGS. 1 to 4 , the connection terminal  1 A includes a terminal connection portion  2  for the connection of a mating terminal (not shown) thereto, a wire connection portion  10  having a wire accommodating space  12  and adapted to be connected to a wire received in the wire accommodating space  12 , and a neck portion  20  disposed between the terminal connection portion  2  and the wire connection portion  10 . This connection terminal  1 A is formed by bending a single electrically-conductive sheet into a predetermined shape. 
     The terminal connection portion  2  includes a tubular portion  3  defined by a lower wall  4  (a first wall), opposite side walls  5  and an upper wall  6  (a second wall). A resilient contact piece portion  7  is provided within the tubular part  3 . When the mating terminal is inserted into the tubular part  3 , this mating terminal is held in intimate contact with the tubular part  3  by a restoring force of the resiliently-deformed resilient contact piece portion  7  and therefore is electrically connected to the connection terminal  1 A. A rear end  6   a  of the upper wall  6  of the tubular part  3  disposed adjacent to the neck portion  20  serves as a lance engagement member  8 . The connection terminal  1 A is accommodated in a terminal accommodating chamber of a connector housing (not shown), and a lance provided within the terminal accommodating chamber is engaged with the lance engagement member  8 , thereby fixing the connection terminal  1 A relative to the connector housing. 
     The neck portion  20  includes a lower wall  21  (a third wall) extending continuously from the lower wall  4  of the tubular part  3 , and opposite side walls  22  (standing walls) extending continuously respectively from the opposite side walls  5  of the terminal connection portion  2 . The neck portion  20  is formed such that a width W 3  of the neck portion  20  between the opposite side walls  22  is decreasing gradually toward the wire connection portion  10 . A width of an end of the neck portion  20  on a side of the terminal connection portion  2  (a front end) is equal to a width W 1  of the terminal connection portion  2 , and a width of an end of the neck portion  20  on a side of the wire connection portion  10  (a rear end) is equal to a width W 2  of the wire connection portion  10  (more specifically, that portion of a surrounding wall  11  (a bent wall) defining a narrow space portion  12   a ). 
     The wire connection portion  10  has the surrounding wall  11  of a generally U-shaped cross-section extending continuously from the lower wall  21  and opposite side walls  22  of the neck portion  20 , and the wire accommodating space  12  is defined by this surrounding wall  11 . The wire accommodating space  12  includes the narrow space portion  12   a , a spreading space portion  12   b  extending continuously from a rear end of the narrow space portion  12   a  and increasing gradually in width (or diameter) away from the rear end of the narrow space portion  12   a , and a wide space portion  12   c  extending continuously from a rear end of the spreading space portion  12   b . A pair of first wire press-fastening portions  13  are formed on and project respectively from upper edges of opposite wall portions of that portion of the surrounding wall  11  defining the narrow space portion  12   a . A pair of second wire press-fastening portions  14  are formed on and project respectively from upper edges of opposite wall portions of that portion of the surrounding wall  11  defining the wide space portion  12   c . The pair of first wire press-fastening portions  13  are press-fastened onto an exposed portion of a conductor of the wire to be fixed thereto, while the pair of second wire press-fastening portions  14  are press-fastened onto a sheath of the wire to be fixed to the wire. 
     The opposite side walls  5  of the tubular part  3  are formed such that the front end of the neck portion  20  is disposed forwardly of the rear end  6   a  of the upper wall  6  of the tubular part  3 . In other words, the rear end  6   a  of the upper wall  6  is protruded on a side of the neck portion  20  than connecting parts of the opposite side walls  5  where the opposite side walls  22  are connected. Mores specifically, rear ends  5   a  of the opposite side walls  5  of the tubular part  3  are formed respectively as slanting surfaces slanting forwardly toward the lower wall  4  from the upper wall  6 . 
     Therefore, when the overall length of the connection terminal  1 A is represented by L, the length of the terminal connection portion  2  is represented by L 1 , and the length of the neck portion  20  is represented by L 2 , the longitudinal region of the neck portion  20  and the longitudinal region of the terminal connection portion  20  overlap each other, and the length L 2  of the neck portion  20  is substantially increased without increasing the overall length L of the connection terminal  1 A. Therefore, the width W 2  of the wire accommodating space  12  (more specifically, the narrow space portion  12   a ) of the wire connection portion  10  can be decreased without increasing the rate of gradual decrease of the width W 3  of the neck portion  20 . Therefore, a crack D (as shown in  FIG. 5 ) or the like will not be produced in the connection terminal  1 A by a bending force applied during a press-shaping operation, and therefore such a so-called terminal crack will not develop. With this construction, even when the connection terminal  1 A is designed to meet a small-diameter design of the wire, the overall length L of the connection terminal  1 A does not need to be increased, and besides a terminal crack developing during the manufacture can be prevented. 
     In this embodiment, the rear end  6   a  of the upper wall  6  of the tubular part  3  disposed adjacent to the neck portion  20  serves as the lance engagement member  8  with which the lance of the connector housing (not shown) is adapted to be engaged. Therefore, the position of the rear end  6   a  of the tubular part  3  disposed adjacent to the neck portion  20 , that is, the position of the lance engagement member  8 , is not changed, and therefore the construction of the connector housing also does not need to be changed. 
     In this first embodiment, the rear ends  5   a  of the opposite side walls  5  of the tubular part  3  are formed respectively as the slanting surfaces slanting forwardly downwardly. Therefore, the upper wall  6  of the tubular part  3  of the terminal connection portion  2  is supported by the opposite side walls  5  as far as its rear end, and therefore the strength of the lance engagement member  8  is not reduced. 
     Further, the tubular part  3  can be constructed so that the opposite side walls  5  of the tubular part are not much notched, and therefore the strength of the lance engagement member  8  is prevented from being reduced. 
     In the case where the lance engagement member  8  has a sufficient strength, the rear end portions of the opposite side walls  5  may be notched as indicated in long dashed short dashed lines in  FIGS. 3 and 5 . 
     Second Embodiment 
     As shown in  FIG. 6 , the connection terminal  1 B of this second embodiment differs from the connection terminal  1 A of the first embodiment only in that a corner portion into which a rear end  5   a  of each of opposite side walls  5  of a tubular part  3  of a tubular part  3  and an upper edge  22   a  of a corresponding one of opposite side walls  22  of a neck portion  20  merge is formed into an arcuate surface  23 . The other construction of the connection terminal  1 B is similar to that of the connection terminal  1 A, and therefore explanation thereof will be omitted here, and those portions identical respectively to the corresponding portions of the connection terminal  1 A will be designated by identical reference numerals, respectively. 
     In this second embodiment, also, similar advantageous effects to the first embodiment can be obtained. 
     In this second embodiment, the angle of the corner portion into which the rear end  5   a  of each side wall  5  of the tubular part  3  of the terminal connection portion  2  and the upper edge  22   a  of the corresponding side wall  22  of the neck portion  20  merge is not acute, is rounded for example, and therefore the concentration of stresses on this corner portion can be prevented. Therefore, a crack D (as shown in  FIG. 7 ) or the like is more positively prevented from developing in the connection terminal. 
     Although the present invention has been shown and described with reference to specific preferred embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims. 
     The disclosures of Japanese Patent Application No. 2009-031399 filed Feb. 13, 2009 including specification, drawings and claims is incorporated herein by reference in its entirety.