Abstract:
Electrical connection reliability of a vehicle charge cable socket connector is maintained for a long period. Dust particles and rain drops that inevitably get into a socket contact can be let out through a contact through hole and a housing through hole that extend from inside the socket contact to outside a housing. Such a configuration can avoid adverse effects of dust particles and drain drops on electrical contact and maintain high connection reliability for a long period.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The contents of the following Japanese patent application are incorporated herein by reference,
   NO. 2011-073487 filed on Mar. 10, 2011.   
 
       BACKGROUND 
       [0003]    1. Technical Field 
         [0004]    The present invention relates to a charge cable connector for use in charging a vehicle on which a secondary battery is mounted, such as an electric vehicle. 
         [0005]    2. Description of the Related Art 
         [0006]    Nowadays, ecologically-friendly vehicles such as electric vehicles and plug-in hybrid vehicles are becoming prevalent that use a motor as their main source of driving force and on which a secondary battery is mounted as a means for supplying electric power to the motor. A typical method of charging such a vehicle-mounted secondary battery is to connect the vehicle and a predetermined charger with a charge cable and supply electric power from the charger to the vehicle for charging. Such a charging method requires the provision of connectors that detachably engage the charge port on the vehicle side with the charge cable for mutual electrical connection. 
         [0007]    For ease of description, a connector provided on the vehicle side will hereinafter be referred to as a “plug connector,” and a connector arranged at the end of the charge cable a “socket connector.” Electrical connection terminals of the plug connector and socket connector will be referred to as “plug contacts” and “socket contacts,” respectively. 
         [0008]    Socket contacts often have a cylindrical shape. Plug contacts of pin shape, formed on an opposed plug connector, are inserted into the interiors of the cylindrical socket contacts. The inner peripheries of the socket contacts and the outer peripheries of the plug contacts thereby come into contact with each other for electric conduction. The shape of the socket contacts will be described in more detail. For example, as shown in Japanese Patent No. 3195181 (in particular,  FIGS. 1 to 3 ), a charge connector terminal  11  is typically opened at a side from which a male terminal  21  is inserted, and closed at a bottom end in the direction of insertion. The charge connector terminal  11  is connected to an end of a wire  25 , which leads to a cable, by a wire connection part  23  that lies behind. 
         [0009]    Vehicles are usually charged outdoors. Dust particles can hinder electric conduction between socket contacts and plug contacts. Rain drops can promote erosion of the contact surfaces on the socket contacts and plug contacts. For the purpose of ensuring the electrical connection reliability of the charge cable connector for high-voltage high-current power supply, measures against dust particles and rain drops are indispensable. Various proposals have been made heretofore on this subject. For example, Japanese Patent No. 3195181 discloses an example where an O ring  31  is arranged near an insertion opening  15  of the charge connector terminal  11 . When the male terminal  21  is inserted into the charge connector terminal  11 , the O ring  31  prevents intrusion of muddy water and the like adhering to the outer periphery of the male terminal  21  (see  FIG. 8 ). 
         [0010]    With such a method as disclosed in Japanese Patent No. 3195181, however, it is not possible to let out muddy water and the like that fail to be removed by the O ring and get into the socket contact when mating and unmating the charge cable. The possibility of the foregoing problem has not been successfully dispelled yet. 
       SUMMARY 
       [0011]    The present invention has been achieved in order to solve the foregoing problem. It is thus an object of the present invention to provide a vehicle charge cable socket connector which avoids the adverse effects of dust particles and rain drops entering the interior of a socket contact upon electrical contact, and maintains high electrical connection reliability for a long period even in outdoor use. 
         [0012]    To solve the foregoing problem, a vehicle charge cable socket connector according to claim  1  of the present invention includes: a socket contact that makes contact with a plug contact; and a housing that includes a holding part for holding the socket contact. The socket contact includes a bottom part to be held at by the housing, and an elastic contact piece that extends from the bottom part and comes into elastic contact with a plug connector-side contact. The bottom part includes a hollow that is formed inside, and a socket contact through hole that runs through to extend from the hollow to outside the socket contact. The housing includes a socket contact accommodation part that accommodates the socket contact, and a housing through hole that opens at one end so as to be opposed to the socket contact through hole and opens at the other end to outside the socket connector. Consequently, there is formed a through hole that extends from inside the socket contact to outside the socket connector. 
         [0013]    In a vehicle charge cable socket connector according to claim  2  of the present invention, an outer periphery of the elastic contact piece is covered with a contact cover. The contact cover includes an elastic contact piece accommodation part that accommodates the elastic contact piece, an insertion hole that is formed in an end of the elastic contact piece accommodation part and through which the plug contact passes, and an end annular part that is arranged around the insertion hole. The contact accommodation part includes an end narrow-necked part in whose end an opening for the plug connector-side contact to pass through is formed. The end annular part is in contact with the end narrow-necked part. 
         [0014]    In a vehicle charge cable socket connector according to claim  3  of the present invention, the elastic contact piece is formed by splitting an end part of the socket contact by a split that extends from the end of the socket contact. The contact cover includes a rib part that is formed inside the elastic contact piece accommodation part so as to correspond to arrangement of the split. The rib part is in close contact with end faces of the split. 
         [0015]    In a vehicle charge cable socket connector according to claim  4  of the present invention, the bottom part is cylindrical in shape and includes a notch that is formed by cutting away a part of an outer periphery of the cylindrical bottom part. The holding part has a shape corresponding to that of the outer periphery of the bottom part with the notch. The socket contact is thereby held with its rotation with respect to the housing restricted. 
         [0016]    According to the invention set forth in claim  1 , dust particles and rain drops that enter the interior of the socket contact can be let out through the through hole that extends from inside the socket contact to outside the housing. It is therefore possible to maintain high electrical connection reliability for a long period without adding dustproof or drip-proof members. 
         [0017]    According to the invention set forth in claim  2 , the elastic contact piece is covered with the contact cover, and the end annular part of the contact cover is in contact with the inner side of the end narrow-necked part of the contact accommodation part. Such a configuration can effectively prevent dust particles and rain drops from entering the contact accommodation part. Since no dust particles or rain drops reside in the contact accommodation part, it is possible to prevent dust particles and rain drops from returning to inside the elastic contact piece to affect the electrical contact. High electrical connection reliability can thus be maintained for an even longer period. 
         [0018]    According to the invention set forth in claim  3 , when the elastic contact piece is formed by splitting the end part of the socket contact, the split can be stopped up with the rib that is formed on the contact cover. With such a structure, dust particles and rain drops that enter the interior of the socket contact are guided into the through hole without being reserved in the split, whereby the socket contact is kept clean inside. High electrical connection reliability can thus be maintained for an even longer period. 
         [0019]    According to the invention set forth in claim  4 , the socket contact has a cylindrical bottom part, and the rotation of the socket contact with respect to the housing is restricted. The socket connector can thus be assembled so that the contact through hole and the housing through hole are opposed to each other without fail. Consequently, dust particles and rain drops that enter the interior of the socket contact can be smoothly let out. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a perspective view showing the appearance of a vehicle charge cable socket connector according to an embodiment of the present invention; 
           [0021]      FIG. 2  is a front view showing the vehicle charge cable socket connector according to the embodiment of the present invention; 
           [0022]      FIG. 3  is a perspective view showing the appearance of the vehicle charge cable socket connector according to the embodiment of the present invention in a different angle, along with a plug connector (vehicle side); 
           [0023]      FIGS. 4A and 4B  are diagrams showing a socket contact of the vehicle charge cable socket connector according to the embodiment of the present invention,  FIG. 4A  being a perspective view showing the appearance of the socket contact,  FIG. 4B  being a central longitudinal sectional view; 
           [0024]      FIGS. 5A to 5C  are diagrams showing a socket contact of the vehicle charge cable socket connector according to the embodiment of the present invention along with a contact cover,  FIG. 5A  being a perspective view of the appearance,  FIG. 5B  being a central longitudinal sectional view,  FIG. 5C  being a cross-sectional view of essential parts; 
           [0025]      FIG. 6  is a sectional view of the vehicle charge cable socket connector according to the embodiment of the present invention, taken along line A-A of  FIG. 2 ; 
           [0026]      FIG. 7  is a sectional view of the vehicle charge cable socket connector according to the embodiment of the present invention, taken along line B-B of  FIG. 6 ; and 
           [0027]      FIG. 8  is a diagram showing an example of a conventional vehicle charge cable socket connector. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0028]    A vehicle charge cable socket connector  100  according to an embodiment of the present invention will be described below with reference to  FIGS. 1 to 7 . In the drawings, a charge cable  200  is shown only in part. The other end of the charge cable  200  is connected to a not-shown charger. 
         [0029]      FIG. 1  shows the appearance of the vehicle charge cable socket connector  100  according to the embodiment of the present invention. The socket connector  100  is attached to an end of a charge cable  200  in a watertight manner via an elastic bushing  170 . A cylindrical housing  130  is exposed in part at an end portion of the socket connector  100 . The interior of the cylindrical end portion constitutes a plug connector accommodation part  131 . The plug connector accommodation part  131  accommodates a plug connector  300  to be described later when the plug connector  300  is connected. 
         [0030]    In the present embodiment, the body section extending from the plug connector accommodation part  131  to the busing  170  is composed of a combination of a right cover  150  and a left cover  160  which are separated along the center line. The socket connector  100  can be assembled by fastening the right cover  150  and the left cover  160  with a screw, with the outer peripheries of the housing  130  and the bushing  170  sandwiched between the right cover  150  and the left cover  160 . In the present embodiment, a ring member  140  separate from the housing  130  is arranged inside the plug connector accommodation part  131 . The ring  140  is intended to improve breaking strength against stress from the insertion of the socket connector  100  into the plug connector  300  and the withdrawal of the socket connector  100  from the plug connector  300 . The ring member  140 , however, is not indispensable. 
         [0031]    As shown in  FIG. 2 , the plug connector accommodation part  131  includes contact accommodation parts  132   a  to  132   e  of cylindrical shape, which are arranged in a predetermined positional relationship that is defined by an industrial standard. In the present embodiment, there are arranged a total of five contact accommodation parts  132   a  to  132   e , including a power supply positive electrode, a ground electrode, and a charge control signal electrode. The contact accommodation parts  132   a  to  132   e  each contain a socket contact  110 . 
         [0032]    A lock lever  180  for securely maintaining the connection with the plug connector  300  is arranged at the top of the socket connector  100 . A latch part  181  protruding downward is formed at the end of the lock lever  180 . The lock lever  180  is pivotally supported by bearing holes formed in the right cover  150  and the left cover  160 , respectively, so as to be movable in a seesaw fashion. A coil spring  182  to be described later biases the lock lever  180  in a direction such that the latch part  181  approaches the plug connector accommodation part  131 . 
         [0033]    The housing  130 , the ring member  140 , the right cover  150 , the left cover  160 , and the lock lever  180  described above are all molded of an insulating synthetic resin. 
         [0034]      FIG. 3  shows the appearance of the present embodiment as seen from behind, along with the plug connector  300  to be mated. The plug connector  300  is fixed to the vehicle side. The plug connector  300  has an annular recess  310  for the cylindrical portion of the plug connector accommodation part  131  to be inserted into. The plug connector  300  also has plug contact arrangement holes  320   a  to  320   e  in positions corresponding to the contact accommodation parts  132   a  to  132   e  of the socket connector  100 , respectively. Not-shown plug contacts of pin shape are arranged on the bottoms of the plug contact arrangement holes  320   a  to  320   e.    
         [0035]    A to-be-latched part  330  is arranged at the top of the plug connector  300 . When the socket connector  100  is inserted into the plug connector  300 , the to-be-latched part  330  and the foregoing latch part  181  come into engagement with each other. The plug connector  300  and the socket connector  100  are thereby retained so as not to be detachable. To withdraw the socket connector  100  from the plug connector  300 , the lock lever  180  is gripped in the portion closer to the bushing  170  and pushed down against the biasing force of the coil spring  182 . The latch part  181  is thereby moved upward to release the engagement with the to-be-latched part  330 , which makes withdrawal possible. 
         [0036]      FIGS. 4A and 4B  show a socket contact  110 . The socket contact  110  is made of elastic conductive metal. The socket contact  110  is cylindrical in shape, and includes elastic contact pieces  113   a  to  113   d , a bottom part  111 , and a wire connection part  117  in order from the end side (the side from which a plug contact is inserted). The elastic contact pieces  113   a  to  113   d  are formed by splitting the end portion of the socket contact  110  crisscross by four splits  114   a  to  114   d  which extend from the end. The elastic contact pieces  113   a  to  113   d  are configured so that their ends can make a radially outward elastic displacement with the bottom part  111  as a fulcrum. A plug contact (not shown) has a columnar pin shape, with a diameter somewhat greater than that of the circle that the inner peripheries of the elastic contact pieces  113   a  to  113   d  form. When the plug contact is inserted into the socket contact  110 , the elastic contact pieces  113   a  to  113   d  each make elastic contact with the outer periphery of the plug contact for electric conduction therebetween. 
         [0037]    The bottom part  111  has a hollow  115  inside. The hollow  115  extends from near the fulcrum of the elastic contact pieces  113   a  to  113   d  to the vicinity of the center of the bottom part  111 . A contact through hole  112  is also formed in the vicinity of the center of the bottom part  111 . The contact through hole  112  extends from the outer periphery of the bottom part  111  to the hollow  115 . In the present embodiment, two collar-like portions are arranged around the bottom part  111 . One of the collar-like portions, lying closer to the end side, is partly cut away to form a so-called D-cut shape, or a notch  116 . The wire connection part  117  is formed in a cylindrical shape, extended from the bottom part  111 . An end of a wire  210  included in the charge cable  200  is inserted into the interior of the wire connection part  117 , and soldered to connect the socket contact  110  and the wire  210 . 
         [0038]      FIGS. 5A to 5C  show a socket contact  110  which is covered with a contact cover  120 . In the present embodiment, the contact cover  120  is molded of silicone rubber which is an insulating elastic material. The contact cover  120  has a generally cylindrical shape. An elastic contact piece accommodation part  121  inside the cylinder accommodates the elastic contact pieces  113   a  to  113   d , thereby covering the socket contact  110  from the end to near the contact through hole  112  in the outer periphery of the bottom part  111 . The end portion of the contact cover  120  has an insertion hole  122  for a plug contact to pass through. The insertion hole  122  is surrounded by an end annular part  123  which is constituted by a plane perpendicular to the longitudinal direction of the socket contact  110 . 
         [0039]    As can be seen from  FIG. 5C , the elastic contact piece accommodation part  121  has four rib parts  124   a  to  124   d  inside. The rib parts  124   a  to  124   d  are vertically erected from the inner periphery of the contact cover  120  so as to correspond to the arrangement of the splits  114   a  to  114   d . With the contact cover  120  alone (when not attached to any socket contact), all the four rib parts  124   a  to  124   d  have a thickness somewhat greater than the width of the splits  114   a  to  114   d  when a plug contact is inserted into the socket contact  110 . Such setting of the rib parts  124   a  to  124   d  in thickness makes it possible to maintain the end faces of the splits  114   a  to  114   d  and the rib parts  124   a  to  124   d  in close contact with each other even when a plug contact is inserted into the socket contact  110 . This can effectively prevent dust particles and rain drops from residing between the end faces of the splits  114   a  to  114   d  and the rib parts  124   a  to  124   d.    
         [0040]      FIG. 6  is a central longitudinal sectional view of the present embodiment. As an example, the following description details the contact accommodation part  132   c  which is arranged at the bottom center when seen in a front view. The other contact accommodation parts  132   a ,  132   b ,  132   d , and  132   e  have the same configuration. 
         [0041]    As can be seen from  FIG. 6 , there is formed a through hole in the vicinity of the bottom part  111 , the through hole extending from the hollow  115  to the plug connector accommodation part  131  via the contact through hole  112  and a housing through hole  134 . Dust particles and rain drops that enter the interior of the socket contact  110  are let out from the socket connector  100  via the through hole. This prevents dust particles and rain drops from affecting electrical contact. 
         [0042]    The socket contact  110  is supplied with a high voltage. In order to prevent users from touching the socket contact  110  and receiving an electric shock, the cylindrical contact accommodation unit  132   c  is integrally formed on the housing  130  so as to protrude toward the end. The contact accommodation part  132   c  has an end narrow-necked part  133   c  at its end. The end narrow-necked part  133   c  covers the end of the socket contact  110  to avoid exposure. In the present embodiment, the inner surface of the end narrow-necked part  133   c  and the end annular part  123  of the contact cover  120  are in contact with each other. This can prevent dust particles and rain drops from entering the interior of the contact accommodation part  132   c  through a gap between the inner surface of the end narrow-necked part  133   c  and the end annular part  123  of the contact cover  120 . Since no dust particles or rain drops reside in the contact accommodation part  132   c , it is possible to prevent dust particles and rain drops from returning to the contact portion to affect electrical contact. 
         [0043]    The socket contact  110  is fixed to the housing  130  by pressing the bottom part  111  into a holding part  135   c  from the rear side of the housing  130  to the front side. The shapes of the bottom part  111  and the holding part  135   c  will be described later. The coil spring  182  is intended to bias the lock lever  180  as described above. An end of the coil spring  182  is fixed to a hole that is formed when the right cover  150  and the left cover  160  are combined. The other end is fixed to a hole that is formed in the bottom of the lock lever  180 . 
         [0044]      FIG. 7  is a cross-sectional view showing essential parts including notches  116  according to the present embodiment. The bottom parts  111  of the five socket contacts  110  have similar shapes, each having the same notch  116  as described previously. Holding parts  135   a  to  135   e  are formed by making holes in the housing  130 , with the same shapes as the outer shapes of the bottom parts  111  including the notches  116 . When the socket contacts  110  are pressed into the respective holding parts  135   a  to  135   e , the socket contacts  110  are fixed so as not to be rotatable. The contact through holes  112  and the housing through holes  134   a  to  134   e  are thereby opposed to each other in a favorable position, and are maintained in that state. 
         [0045]    The foregoing embodiment has dealt with the case where the socket connector is shaped straight from its end to the charge cable, i.e., the socket connector is of so-called straight type. However, the range of application of the present invention is not limited thereto. The present invention is suitably applicable to a socket connector of a type where the socket connector is curved into a generally L shape from its end to the charge cable. 
         [0046]    The present invention may be applied to a charge cable socket connector for use in charging a vehicle on which a secondary battery is mounted, such as an electric vehicle. The present invention thereby contributes to a reduction of charging troubles due to dust particles, rain drops, and the like entering inside the connector.