Patent Publication Number: US-6217345-B1

Title: Electrical connector

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector, more particularly to a connector inserted into a connector receiving recess fitted with a flexible print-circuit having a plurality of terminal connecting short strips. The connector also has a plurality of terminals each formed with an elastic contact piece for contracting one of the terminal connecting short strips through an opening of a terminal accommodating chamber of the connector. 
     2. Prior Art 
     A typical one of such connectors is shown in FIG. 8, which is known generally. 
     FIG. 8 shows a connector  1  having a rectangular connector housing  2  provided with a plurality of terminal accommodating chambers  3  (only one chamber is illustrated in FIG. 8) each of which receives a terminal  5  having an elastic contact piece  4 . The connector is inserted in a connector receiving recess  7  fitted with a flexible print-circuit (called as FPC hereinafter)  6 . 
     The plurality of terminal accommodating chambers  3  each have an opening  8  defined in a wall thereof to be opposed to FPC  6  of the connector receiving recess  7 . The elastic contact piece  4  is constructed to project by a given distance from the opening  8 . In addition, the plurality of terminal accommodating chambers  3  each have the opening at the rear end thereof for inserting a terminal  5  into the terminal accommodating chamber  3 . 
     The terminal  5  is made of an electrical conductive metal and has both an elastic contact piece  4  and a wire connection portion  11  that crimps an electrical wire  10 . The elastic contact piece  4  has a contact portion  12  in the middle of a folded-back forward part thereof. The elastic contact piece  4  is projecting from the opening  8  toward the wire connection portion  11 . 
     The connector receiving recess  7  is defined in an instrument case  13  so as to receive the connector housing  2 . FPC  6  arranged in the connector receiving recess  7  has a plurality of terminal connecting short strips (not shown) each connecting with the contact portion  12  of one of the terminals  5 . 
     When the connector receiving recess  7  receives the connector  1 , each elastic contact piece  4  deflects resiliently and abuts against the terminal connecting short strip (not shown) for electrical contact thereof with a suitable contact force. 
     Now, an object of the invention will be discussed hereinafter. 
     In the aforementioned prior art, as shown in FIG. 8, there may be variations in distance A between the opposite walls of the connector receiving recess  7 , in distance B between FPC  6  and the second wall, and in an original height C from a bottom wall of the connector housing  2  to the contact portion  12 . Thus, a deflection allowance D of the elastic contact piece  4  is not defined reliably, causing disadvantageously an unreliable contact force between the elastic contact piece  4  and the terminal connecting short strip. 
     In addition, since the instrument case  13 , of which the connector receiving recess  7  and the connector housing  2  are made of synthetic resin, is influenced by a surrounding high temperature, the distances A, B of the connector receiving recess  7  vary in a larger range so that the elastic contact piece  4  may have an undesirable smaller contact force. 
     Meanwhile, the elastic contact piece  4  is limited in width, thickness, and deflection since it must be located in the terminal accommodating chamber  3  in relation to the connector receiving recess  7 . Moreover, the elastic contact piece  4  is limited in material due to electric conductivity. 
     Furthermore, when the elastic contact piece  4  has a comparatively large elastic coefficient, the contact force varies in a lager range corresponding to the deflection of the elastic contact piece  4 . Thus, a small variation of the dimensions A, C may cause a comparatively large variation of the contact force of the elastic contact piece  4 , which may make the elastic contact piece  4  yield with time. Accordingly, as mentioned above, the elastic contact piece  4  provides an unsteady contact force against the terminal connecting short strip. 
     SUMMARY OF THE INVENTION 
     In order to eliminate such disadvantages, an object of the present invention is to provide a connector having an elastic contact piece that provides a steady contact force against a terminal connecting short strip of a connector receiving recess. 
     For achieving the object, in a first configuration according to the present invention, an electrical connector includes a connector housing, a plurality of terminals, an assisting means, and a support means. The connector housing can be received in a connector receiving recess having a first wall fitted with a plurality of terminal connecting short strips. The connector housing has a plurality of terminal accommodating chambers with openings through which the plurality of terminal accommodating chambers communicate with the first wall side of the connector receiving recess. Furthermore, each terminal has a wire connection portion and an elastic contact piece extending from the wire connection portion. The elastic contact piece is defined by folding back a forward part of the terminal toward the wire connection portion. The folded-back portion has a contact portion formed at the middle part thereof to contact the terminal connecting short strip through the opening. The plurality of terminals are inserted in the terminal accommodating chambers of the connector housing. Meanwhile, the assisting means can resiliently abut against a second wall opposing to the first wall in respect of the connector receiving recess, which urges additionally the elastic contact piece against the terminal connecting short strip. The support means formed in the connector housing is engaged with the assisting means to hold it. 
     When thus configured connector is inserted into the connector receiving recess, the elastic contact piece abuts against the terminal connecting short strip to resiliently deflect to make electrical connection thereof with a suitable contact force while the assisting means resiliently abuts against the second wall of the connector receiving recess, even if there are variations in the distance between the first and second walls of the connector receiving recess and in the connector height that is the height of the contact portion of the elastic contact piece, and even when the elastic contact piece has yielded with time. The assisting means can act to keep a suitable contact force between the contact portion and the terminal connecting short strip. 
     This, as discussed above, allows a steady contact force of the elastic contact piece against the terminal connecting short strip of the connector receiving recess, providing a reliable electrical connector. 
     In a second configuration of the present invention, which is dependent on the electrical connector described in the first configuration, the assisting means is a spring member made of a metal wire rod to have a coiled portion and a couple of arms. The coiled portion is defined by coiling an intermediate portion of the metal wire rod to be engageable with the support means. One of the arms has a reaction portion abutting against the second wall of the connector receiving recess. 
     Thus, in regard to the assisting means consisting of the spring member including the coiled portion and the couple of the arms, when the reaction portion resiliently abuts against the second wall of the connector receiving recess, the couple of arms resiliently deflect against the wall to pivot around the coiled portion toward each other. Thus, even if there are the variations in size as mentioned above, the assisting means always serves additionally to provide a steady contact force to the elastic contact piece. Moreover, the assisting means requiring no electrical conductivity may be made of a more durable wire rod having a higher allowable stress and a higher yield stress like a piano wire. 
     Accordingly, the assisting mean consisting of the spring member allows a connector having a high reliability. Advantageously, the spring member can be easily formed. 
     In a third configuration of the present invention, which is dependent on the electrical connector described in the second configuration, the support means has a supporting shaft receiving the coiled portion and a couple of arm stoppers corresponding to the couple of arms. 
     The support means and such configured arms can provide a resilient force around the coiled portion. 
     Thus, the arms held by the arm stoppers can provide an additional resilient force to the elastic contact piece, and also the location of the arm stoppers can adjust the additional force. 
     The support means simple in design is easily assembled into the connector housing with a comparatively lower cost. 
     In a fourth configuration of the present invention, which is dependent on the electrical connector described in the first configuration, the assisting means is a spring member made of the metal wire rod and has a pair of coiled portions, a cross over arm, and a pair of arms. Each coiled portion is defined by coiling an intermediate portion of the metal wire rod so as to engage with the support means. The coiled portions are positioned to oppose to each other. The pair of arms each extend from the coiled portion so as to oppose to one another. The cross over arm connects to both the pair of coiled portions and has a reaction portion for abutting against the second wall of the connector receiving recess. 
     In the assisting means consisting of the spring member having the coiled portions, the cross over arm, and the pair of arms, the pair of arms and the cross over arm resiliently deflect inwardly around the coiled portion. Meanwhile, the reaction portion resiliently abuts against the second wall of the connector receiving recess. Thus, even if there are such variations in size as mentioned above, the assisting means always acts to provide a steady contact force on the elastic contact piece. Moreover, the assisting means requiring no electrical conductivity may be made of a more durable wire rod having a higher allowable stress and a higher yield stress like a piano wire. Thus, the spring member composing the assisting means allows a connector having a high reliability. Advantageously, the spring member can be easily formed. 
     In a fifth configuration of the present invention, which is dependent on the electrical connector described in the fourth configuration, the reaction portion of the cross over arm has a projection facing toward the second wall of the connector receiving recess, which can effectively receive a reaction force acted on the spring. 
     In a sixth configuration of the present invention, which is dependent on the electrical connector described in the fourth configuration, the support means has a pair of supporting shafts engageable with the couple of coiled portions, two arm stoppers respectively corresponding to the first and second opposite arms, and a cross over arm stopper corresponding to the cross over arm. The pair of arms and the cross over arm can provide a resilient force in cooperation with the coiled portions. 
     Furthermore, the location of the arm stoppers and the cross over arm stopper allows adjustment of the additional force of the spring member to assist the elastic contact piece as cooperated with the arm stoppers and the cross over arm stopper. 
     The support means simple in design is easily assembled in to the connector housing with a comparatively lower cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view showing a connector of an embodiment according to the present invention; 
     FIG. 2 is a side view of the connector shown in FIG. 1; 
     FIG. 3 is a side view showing a state that the connector of FIG. 1 has been inserted in the connector receiving recess; 
     FIG. 4 is an exploded perspective view showing a connector of another embodiment of the present invention; 
     FIG. 5 is a side view of the connector shown in FIG. 4; 
     FIG. 6 is a side view showing the connector of FIG. 4 which has been inserted into the connector receiving recess; 
     FIG. 7 is a perspective view showing another example of the spring member of FIG. 4; and 
     FIG. 8 is a sectional view showing a prior-art connector. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the accompanied drawings, embodiments of the present invention will be discussed hereinafter. 
     Referring to FIG. 1, denoted  21  is a connector. The connector  21  has a connector housing  22  made of synthetic resin, a plurality of terminals  23  accommodated in the connector housing  22  (four terminals are illustrated in this embodiment as an example), and a pair of spring members  24 ,  24  (corresponding to the assisting means described in the summary of the invention) supported by the connector housing  22 . The connector  21 , for example, will be inserted into a connector receiving recess  26  formed in an instrument case  25  of an automotive vehicle for electrical connection thereof. 
     The connector housing  22  has been formed by injection molding or the like and has four terminal accommodating chambers  27  therein. Each terminal accommodating chamber  27  has a conventional terminal locking means such as a lance (not shown). The connector receiving recess  26  has an upper wall  26   a  (see FIG. 2) which communicates with each terminal accommodating chamber  27  through four rectangular openings  28  defined in a top wall  22   a  of the connector housing  22 . 
     The connector housing  22  has side walls  22   b,    22   b,  which have a pair of column-shaped supporting shafts  29 ,  29  (corresponding to the support means described in the summary of the invention, and only one shaft is illustrated) at the rear side thereof. That is, the supporting shafts  29 ,  29  are laterally extending and located in the side of openings  27   a  of the terminal accommodating chambers  27 . The side walls  22   b,    22   b  also each have a rib-like first arm stopper  30  and a column-shaped second arm stopper  31  at the fore end side thereof. The first and second arm stoppers  30 ,  31  (corresponding to the support means described in the summary of the invention and only one side stoppers are illustrated) are formed on each side wall  22   b  to align with opposite side ones. 
     The terminal  23  is stamped out from an electrically conductive metal and formed by bending. The terminal  23  has an elastic contact piece  32  and a wire connection portion  34  connected to an electrical wire  33  by crimping. The elastic contact piece  32  has a folded-back portion defined by folding back a forward extending part of the contact piece  32  toward the wire connection portion  34 . In the middle of the folded-back portion is formed a raised contact portion  35  which can contact one of terminal connecting short strips  41  (described later) of a connector receiving recess  26  through one of the openings  28 . 
     Each of the spring members  24 ,  24  is made of a metal wire rod to have a coiled portion  36  with an inside diameter engaging with the supporting shaft  29  at a middle thereof. From each end of the coiled portion  36  there are extending each of a first arm  37  and a second arm  38 . The first arm  37  and the second arm  38  are divergently resiliently opposed to each other by way of the coiled portion  36 . The second arm  38  has a reaction portion  39  at a forward portion thereof. The reaction portion  39  is formed so as to project downwardly from a bottom wall  22   c  (see FIG. 2) of the connector housing  22  when assembled in the connector housing  22 . 
     Meanwhile, the connector receiving recess  26 , as shown in FIGS. 1,  2 , has an upper wall  26   a  corresponding to the top wall  22   a  of the connector housing  22  and fitted with a flexible print-circuit (called as FPC hereinafter)  40  along a surface of an instrument case  25  to be secured thereto by bonding or the like. A lower wall  26   b  opposed to the upper wall  26   a  has a tapered portion  26   c  at the connector receiving side thereof for guiding the reaction portions  39 ,  39 . 
     FPC  40  is a conventional circuit which will not be discussed in detail herein. FPC  40  has a plurality (four in the embodiment) of terminal connecting short strips  41  each arranged to electrically contact one of the elastic contact pieces  32 . 
     Alternatively, FPC  40  may be replaced by an electrical wiring board having terminal connecting pieces. 
     Next, referring to FIGS. 1 to  3 , an assembling step of the connector  21  and an insertion step of the same to the connector receiving recess  26  will be discussed. 
     As shown in FIG. 1, first, each terminal accommodating chamber  27  of the connector housing  22  receives one of the terminals  23 . Each received terminal  23  is locked by a terminal locking means (not shown) and the contact portion  35  of the elastic contact piece  32  protrudes from the opening  28 . 
     Next, the pair of spring members  24 , 24 , as shown in FIG. 2, are engaged with the side walls  22   b,    22   b  (as the connector housing  22  is symmetrical, only one side arrangement is illustrated). That is, the coiled portion  36  is engaged with the supporting shaft  29 , and the first arm  37  abuts against an inside face of the first arm stopper  30 . The second arm  38  deflects in the direction shown by arrow P to abut against an inner face of the second arm stopper  31 , completing the mounting of the spring members  24  on the connector  21 . 
     Then, the connector  21  is inserted into the connector receiving recess  26  in arrow Q direction shown in FIG.  2 . At first, the reaction portions  39 ,  39  slidingly abut against the tapered portion  26   c,  so that the reaction portions  39 ,  39  are urged to move upward toward the first arm  37  until the lowest points of the reaction portions  39 ,  39  are positioned on a bottom wall  22   c  of the connector housing  22  as shown in FIG.  3 . At the same time, the spring members  24 ,  24  resiliently abut against the lower wall  26   b  of the connector receiving recess  26 . 
     The contact portion  35  of each elastic contact piece  32  slidably contacts the associated terminal connecting short strip  41  (see FIG. 1) to be resiliently depressed inward, so that the contact portion  35  resiliently abuts against the terminal connecting short strip  41  (see FIG. 1) with a suitable contact force (determined by the construction of the spring member  24  and the elastic contact piece  32 ) for electrical connection thereof. 
     Thus, even if there are variations in the distance between the walls  26   a,    26   b  of the connector receiving recess  26  (corresponding to distance B discussed in FIG. 8) and in the height from the bottom wall  22   c  of the connector housing  22  to the contact portion  35  (corresponding to distance C discussed in FIG.  8 ), or even when the elastic contact piece  32  has yielded with time, the spring members  24 , 24  serve to keep an adequate contact force between the contact portion  35  and the terminal connecting short strip  41  (see FIG.  1 ). 
     Hence, the connector  21  discussed above can has a steady contact force to be a reliable one. 
     Referring to FIGS. 4 to  6 , another embodiment will be discussed, and the same numeral will be applied to the same component as used in the aforementioned connector  21 . 
     In FIG. 4, a connector  51  has a connector housing  52  made of synthetic resin, a plurality (four in the embodiment) of terminals  23  inserted into the connector housing  52 , and a spring member  53  held by the connector housing  52  (corresponding to the assisting means described in the summary of the invention). The connector  51  is inserted into a connector receiving recess  26  formed in an instrument case  25  for electrical connection thereof as well as the first embodiment. 
     The connector housing  52  has been formed in a rectangular shape by injection molding or the like and has four terminal accommodating chambers  27  therein. Each terminal accommodating chamber  27  has a terminal locking mean (not shown) like a lance. The connector housing  52  has a top wall  52   a  formed with four rectangular openings  28  each opposing to one of the terminal accommodating chambers  27 . 
     The connector housing  52  has side walls  52   b,    52   b  each provided with a column-shaped supporting shafts  29  at the rear side thereof. That is, the supporting shafts  29 ,  29  are laterally extending and located in the side of openings  27   a  of the terminal accommodating chambers  27 . The side walls  52   b,    52   b  also each have a rib-like arm stopper  30  and a rib-like cross over arm stopper  54  at the fore end side thereof. The arm stoppers  30 ,  54  (corresponding to the support means described in the summary of the invention and only one side stoppers are illustrated) are formed on each side wall  52   b  to align with opposite side ones. The connector housing  52  has a bottom wall  52   c  (see FIG. 6) having a concave, second cross over arm stopper  55 . 
     The spring member  53  is made of a metal wire rod and has a pair of coiled portions  56 ,  56  each formed at an intermediate part thereof having an inside diameter engageable with the supporting shaft  29 . From each coiled portion  56  is straightly extending an arm  57 . The pair of coiled portions  56 ,  56  are connected by a U-shaped cross over arm  58 . The arms  57 ,  57  and the cross over arm  58  move resiliently against each other by way of the coiled portions  56 ,  56 . The cross over arm  58  has a reaction portion  59  extending laterally relative to the connector housing  52 . The reaction portion  59  projects from the bottom wall  52   c  of the connector housing  52  to be engageable with the second cross over arm stopper  55  when the spring member  53  has been attached to the connector housing  52 . 
     Referring to FIGS. 4 to  6 , assembling steps of the connector  51  and an insertion step of the connector  51  into the connector receiving recess  26  will be discussed hereinafter. 
     As shown in FIG. 4, first, each terminal accommodating chamber  27  of the connector housing  52  receives one of the terminals  23 . And, each received terminal  23  is locked by the terminal locking means (not shown), and the contact portion  35  of the elastic contact piece  32  is protruding from the opening  28 . 
     Next, the spring member  53 , as shown in FIG. 5, engages with the side walls  52   b,    52   b  of the connector housing  52 . That is, the coiled portions  56 ,  56  each receive one of the supporting shafts  29 ,  29 , and the arms  57 ,  57  each abut against one of the arm stoppers  30 ,  30 . The cross over arm  58  is urged in arrow R direction to abut against an inner face of each of the cross over arm stoppers  54 ,  54 . However, the engagement of the spring member  53  may be made before the engagement of the cross over arm  58 . The fitting steps complete the assembling of the connector  51 . 
     Then, the connector  51  is inserted into the connector receiving recess  26  in arrow S direction as shown in FIG.  5 . Thereby, the reaction portion  59  abuts against the tapered portion  26   c,  so that the reaction portion  59  moves upward toward the arms  57 ,  57  as shown in FIG. 6 to engage with the second cross over arm stopper  55 . At the same time, the spring member  53  resiliently abuts against the lower wall  26   b  of the connector receiving recess  26 . 
     Furthermore, the contact portion  35  of each elastic contact piece  32  slidingly abuts against one of the terminal connecting short strips  41  (see FIG. 4) to resiliently urge the elastic contact piece  32  inwardly so as to contact the terminal connecting short strip  41  with an adequate contact force (determined by the spring member  53  and the elastic contact piece  32 ) for electrical connection thereof. 
     Thus, even if there are variations as to the distance between the upper and lower walls  26   a,    26   b  of the connector receiving recess  26  (corresponding to distance B discussed in FIG. 8) and as to the height from the bottom wall  52   c  of the connector housing  52  to the contact portion  35  (corresponding to distance C discussed in FIG.  8 ), or even when the elastic contact piece  32  has yielded with time, the spring member  53  serves to keep an adequate contact force between the contact portion  35  and the terminal connecting short strip  41  (see FIG.  4 ). 
     Hence, the connector  51  discussed above can have a steady contact force to be a reliable one as well as the connector  21 . 
     In addition, the reaction portion  59  of the spring member  53  may have projections  60 ,  60  shown in FIG. 7 so that such a spring member  53 ′ can receive well distributed reaction forces. 
     Moreover, the spring members  24 ,  53 , and  53 ′ requiring no electrical conductivity may be made of a more durable wire rod having a higher allowable stress and a higher yield stress. Thus, the spring member composing the assisting means allows the connector having a high reliability. Advantageously, the spring members can be easily formed. 
     Furthermore, the support means including the supporting shafts  29 ,  29  and the arm stoppers  30 ,  30  (shown in FIG. 1) can assist the elastic contact piece  32  in cooperation with the arm stoppers  31 ,  31 . In addition, the location of the arm stoppers  30 ,  31  allows adjustment of the additional force of the spring member  24 . The support means simple in design is easily assembled into the connector housing with a comparatively lower cost.