Patent Publication Number: US-9431741-B2

Title: Socket contact

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a socket contact. 
     2. Description of the Related Art 
     Conventionally, as shown in  FIGS. 11 and 12 , there has been proposed a charging connector terminal  955  (socket contact) including an electric contact portion  913  having a hollow cylindrical shape, and an auxiliary spring (spring member)  963  which has an annular shape and is fitted on an outer periphery of the electric contact portion  913  (see Japanese Patent Laid-Open Publication No. H8-222314). 
     Four slits  957  extending in the direction of the central axis of the electric contact portion  913  are formed in the hollow cylindrical electric contact portion  913 , at equally-spaced intervals in a circumferential direction of the electric contact portion  913 , whereby the electric contact portion  913  is divided into four contact plates  959 . Front end portions of the four contact plates  959  are elastically deformable in respective radial directions of the electric contact portion  913 . Outer grooves  961  extending in the circumferential direction of the electric contact portion  913  are formed in respective outer peripheries of the four contact plates  959 . 
     The inner diameter of the auxiliary spring  963  is slightly smaller than the outer diameter of the electric contact portion  913 . The auxiliary spring  963  is fitted in the outer grooves  961 . 
     When an electric contact portion  921 A, which has a pin shape, of a male terminal  921  is inserted into the electric contact portion  913  of the charging connector terminal  955 , the respective front end portions of the four contact plates  959  are displaced outward, whereby the diameter of the auxiliary spring  963  is increased. At this time, the inner peripheries of the front end portions of the contact plates  959  are pressed against the outer periphery of the electric contact portion  921 A of the male terminal  921 , by the returning forces of the contact plates  959  and the auxiliary spring  963 , whereby predetermined contact forces are generated between the front end portions of the contact plates  959  of the charging connector terminal  955  and the electric contact portion  921 A of the male terminal  921 . 
     As described above, for the charging connector terminal  955 , a structure is employed in which the auxiliary spring  963  is fitted in the outer grooves  961  formed in the outer peripheries of the four contact plates  959 , and hence holding forces with which the outer grooves  961  hold the auxiliary spring  963  are small, so that there is a fear that the auxiliary spring  963  is easily removed from the electric contact portion  913 . 
     Further, in the case of the structure including the outer grooves  961  formed in the outer peripheries of the four contact plates  959 , the socket contact is manufactured by cutting, and hence the amount of waste material is large. This is one of factors which increase the manufacturing costs of the socket contact (charging connector terminal  955 ). 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of these circumstances, and an object thereof is to provide a socket contact that is capable of reducing manufacturing costs thereof and has a spring member difficult to be removed from a socket contact body. 
     To attain the above object, the present invention provides a socket contact comprising a socket contact body including a contact portion, which has a hollow cylindrical shape, for receiving a pin contact therein, and a spring member fitted on the socket contact body, the spring member including an elastic annular portion fitted on an outer periphery of the contact portion, and at least one protruding portion provided on the elastic annular portion, wherein the contact portion has at least one slit formed therein which extends in a direction of receiving the pin contact, wherein the contact portion has a receiving portion formed therein for receiving the protruding portion and limiting movement of the elastic annular portion in a direction parallel to the direction of receiving the pin contact, and wherein the contact portion has a contact point portion that is pressed against an outer periphery of the pin contact by returning force of the elastic annular portion when the pin contact is received into the contact portion. 
     Preferably, when the receiving portion has received the protruding portion therein, a front end of the protruding portion does not protrude inward of an inner peripheral surface of the contact portion. 
     Preferably, the receiving portion is a hole or a cutout. 
     Preferably, the socket contact body includes a body portion having a cylindrical shape, and a connection portion provided at one end of the body portion, for being connected to an object to be connected, and the contact portion has elasticity, and is provided at the other end of the body portion. 
     More preferably, the object to be connected is a wire, and the connection portion is formed to have a hollow cylindrical shape such that the connection portion can receive one end of the wire therein. 
     Preferably, the at least one slit comprises four slits, and the four slits are arranged at equally-spaced intervals in a circumferential direction of the contact portion. 
     Preferably, the socket contact body is made of a pure copper-based material. 
     Preferably, the spring member is made of a metal material having high heat resistance. 
     Preferably, the socket contact body except the receiving portion is made by cold forging. 
     According to the present invention, it is possible to provide a socket contact that is capable of reducing manufacturing costs thereof and has a spring member difficult to be removed from a socket contact body. 
     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a socket contact according to a first embodiment of the present invention. 
         FIG. 2  is a perspective view of the socket contact shown in  FIG. 1  in a state before a spring member is fitted on a socket contact body. 
         FIG. 3  is a front view of the socket contact body appearing in  FIG. 1 . 
         FIG. 4  is a side view of the socket contact body appearing in  FIG. 1 . 
         FIG. 5  is a rear view of the socket contact body appearing in  FIG. 1 . 
         FIG. 6  is a cross-sectional view taken along VI-VI in  FIG. 3 . 
         FIG. 7  is a partial cross-sectional view taken along VII-VII in  FIG. 3 . 
         FIG. 8  is a perspective view of a socket contact body of a socket contact according to a second embodiment of the present invention. 
         FIG. 9  is a perspective view of the socket contact body shown in  FIG. 8 , taken obliquely from the rear. 
         FIG. 10  is a perspective view, partly in cross-section, of the socket contact body shown in  FIG. 8 . 
         FIG. 11  is a side view of a conventional socket contact (charging connector terminal). 
         FIG. 12  is a cross-sectional view of the socket contact shown in  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described in detail with reference to the drawings showing preferred embodiments thereof. 
     First, a socket contact according to a first embodiment of the present invention will be described with reference to  FIGS. 1 to 7 . 
     The socket contact  10  is comprised of a socket contact body  13  and a spring member  15 . The socket contact  10  according to the present embodiment is used as a large-current socket contact. 
     The socket contact body  13  includes a contact portion  131 , a connection portion  132 , and a body portion  133 . 
     The connection portion  132 , which has a disk shape and is connected e.g. to a bus bar (object to be connected), not shown, is provided at one end of the body portion  133  which has a cylindrical shape. The contact portion  131 , which has a hollow cylindrical shape, is provided at the other end of the body portion  133 . Four slits  131 A and two holes (receiving portions)  131 B are formed in the contact portion  131 . 
     The contact portion  131  receives a pin contact, not shown, therein. The outer diameter of a front end portion of the contact portion  131  is slightly smaller than the outer diameter of a rear end portion of the contact portion  131 . 
     Each slit  131 A extends in a receiving direction DI in which the contact portion  131  receives the pin contact therein. The four slits  131 A are arranged at equally-spaced intervals in a circumferential direction of the contact portion  131  (see  FIG. 3 ). The contact portion  131 , which has a hollow cylindrical shape, is formed with the four slits  131 A, whereby four contact pieces  131 C are formed. A contact point portion  131 D for being brought into contact with an outer periphery of the pin contact is formed on the inner periphery of a front end portion of each contact piece  131 C. 
     Each hole  131 B is formed such that it meets one of the slits  131 A, and is divided by the slit  131 A into two in the circumferential direction of the contact portion  131 . The two holes  131 B are opposed to each other in a diametrical direction of the contact portion  131 . 
     The connection portion  132  is connected to the bus bar e.g. by ultrasonic bonding, welding, or soldering. Note that the connection portion  132  may be connected to the bus bar with bolts by forming screw holes (not shown) in an end face of the connection portion  132 . 
     The body portion  133  includes a small-diameter portion  133 A and a large-diameter portion  133 B. The outer diameter of the large-diameter portion  133 B is larger than the outer diameter of the small-diameter portion  133 A and is smaller than the outer diameter of the connection portion  132 . 
     The respective central axes of the contact portion  131 , the body portion  133 , and the connection portion  132  coincide with each other. 
     The socket contact body  13  except the contact portion  131  has a solid structure (structure having no void therein). 
     The socket contact body  13  has no hidden portion other than the holes  131 B, as viewed from the front (see  FIG. 3 ). Therefore, as described hereinafter, it is possible to form the socket contact body  13  except the holes  131 B by cold forging. 
     The spring member  15  includes an elastic annular portion  151  and two protruding portions  152 . When the contact portion  131  of the socket contact body  13  receives the pin contact therein, the elastic annular portion  151  of the spring member  15  is elastically deformed, and the contact point portions  131 D of the contact portion  131  are pressed against the outer periphery of the pin contact by the returning force of the elastic annular portion  151 . 
     The elastic annular portion  151  is formed by bending a metal plate into an annular shape, and is elastically deformable in a diametrical direction thereof. A protruding portion  151 A is formed at one end of the elastic annular portion  151  in a circumferential direction thereof, and a recess  151 B for receiving the protruding portion  151 A is formed at the other end of the elastic annular portion  151 . The inner diameter of the elastic annular portion  151  is smaller than the outer diameter of the contact portion  131  measured when the front end portion of the contact portion  131  is made narrower in diameter to form a smaller opening. 
     In the present embodiment, before the spring member  15  is fitted on the outer periphery of the contact portion  131 , the two protruding portions  152  protrude straight from a front end of the elastic annular portion  151  (one end of the elastic annular portion  151  in the direction of the central axis thereof) in a direction opposite to the receiving direction DI (see  FIG. 2 ). The two protruding portions  152  are opposed to each other in the diametrical direction of the elastic annular portion  151 . 
     After the spring member  15  is fitted on the outer periphery of the contact portion  131 , the protruding portions  152  are bent in the radial direction of the elastic annular portion  151 , and front ends of the protruding portions  152  are inserted into respective associated ones of the holes  131 B (see  FIG. 1 ), as described hereinafter. As a consequence, movement of the spring member  15  in a direction parallel to the receiving direction DI is restricted. 
     However, the protruding portions  152  are bent such that the front ends thereof do not protrude into the inner space of the contact portion  131 . Further, when the front end of each protruding portion  152  is inserted into the associated hole  131 B, a predetermined clearance is formed between the protruding portion  152  and the inner peripheral surface of the hole  131 B. This clearance is provided for preventing the contact portion  131  from interfering with movement of the protruding portion  152  in the circumferential direction of the contact portion  131  caused when the pin contact is inserted into the contact portion  131 , to thereby prevent the contact portion  131  from blocking elastic deformation of the elastic annular portion  151  in a direction in which the elastic annular portion  151  is increased in diameter. Therefore, the length of each hole  131 B in the circumferential direction of the contact portion  131  is sufficiently larger than the length of each protruding portion  152  in the circumferential direction of the contact portion  131 . 
     Note that when only one protruding portion  152  and only one hole  131 B are employed, it is only required to insert the protruding portion  152  deep into the hole  131 B, and it is not essential to provide the clearance described above. This is because if one protruding portion  152  and one hole  131 B are provided, the elastic deformation of the elastic annular portion  151  in the direction in which the elastic annular portion  151  is increased in diameter is not blocked. 
     Next, a method of manufacturing the socket contact  10  will be described with reference to  FIGS. 1 and 2 . 
     To manufacture the socket contact body  13 , first, a socket contact body intermediate (socket contact body  13  in a state in which the portions other than the holes  131 B are formed), not shown, is formed from a cylindrical material (not shown) made of a pure copper-based material, by cold forging. Examples of the pure copper-based material include pure copper materials, such as oxygen-free copper and tough pitch copper, and copper materials having a purity lower than but close to the purity of the pure copper materials. 
     Next, the two holes  131 B are formed by removal work, such as cutting. 
     The socket contact body  13  is completed through the above-described processes. 
     To manufacture the spring member  15 , first, a spring member intermediate, not shown, is formed by blanking a metal plate made of a metal material having high heat resistance into a predetermined shape (developed shape of the spring member  15 ) through press work. Examples of the metal material having high heat resistance include stainless steel, zirconium copper, and titanium copper. 
     Next, the elastic annular portion  151  is formed by bending the spring member intermediate into an annular shape through bending work. At this stage, the protruding portions  152  are not bent, which means that the spring member  15  has not been completed yet, and hence in a strict sense, the bent metal plate is not the spring member  15  but it is still a spring member intermediate. However, the spring member intermediate at this stage is also referred to as the spring member  15 , for convenience of description. 
     To assemble the spring member  15  to the socket contact body  13  manufactured as described above, first, the front end portion of the contact portion  131  is made narrower in diameter until the contact pieces  131 C are brought into contact with each other in the circumferential direction of the contact portion  131 . 
     Next, the diameter of the elastic annular portion  151  of the spring member  15  is increased, and the spring member  15  is fitted on the contact portion  131  of the socket contact body  13  in a manner such that the spring member  15  is wound around the outer periphery of the contact portion  131 . After that, the spring member  15  is positioned with respect to the contact portion  131  such that the holes  131 B and associated ones of the protruding portions  152  are opposed to each other. 
     Finally, the front ends of the protruding portions  152  are bent and inserted into the respective associated ones of the holes  131 B, using a jig having a bar-like shape (not shown). In doing this, care is taken to ensure that the front ends of the protruding portions  152  do not protrude into the inner space of the contact portion  131  of the socket contact body  13  (space inward of the inner peripheral surface of the contact portion  131 ). Note that although in the present embodiment, the front ends of the protruding portions  152  are bent after the spring member  15  is fitted on the socket contact body  13 , the front ends of the protruding portions  152  may be bent in advance before the spring member  15  is fitted on the socket contact body  13 . 
     The fitting of the spring member  15  on the socket contact body  13  is completed through the above-described processes, whereby the socket contact  10  is completed. 
     According to the present embodiment, the movement of the spring member  15  in the direction parallel to the receiving direction DI is restricted by inserting the protruding portions  152  of the spring member  15  into the holes  131 B of the socket contact body  13 , and hence there is no need to form the outer grooves  961  (see  FIGS. 11 and 12 ) surrounding the outer periphery of the contact portion  131  through cutting work for the purpose of prevention of removal of the spring member  15 . As a result, when the socket contact body  13  is manufactured, the amount of waste material is largely reduced, and hence manufacturing costs can be reduced. Further, the holes  131 B are through holes extending through the contact pieces  1310  and have a large holding force for holding the protruding portions  152 . Therefore, compared with the outer grooves  961  formed in the outer peripheries of the contact plates  959  (see  FIGS. 11 and 12 ), the holes  131 B make the spring member  15  more difficult to be removed from the socket contact body  13 . Therefore, there is no need to provide the contact portion  131  with e.g. a protruding stopper (not shown) protruding outward from the outer periphery thereof so as to limit the movement of the spring member  15  in the direction parallel to the receiving direction DI. 
     Further, since the metal material having high heat resistance is used as the material of the spring member  15 , the spring member  15  is resistant to creep deformation, and the contact stability between the pin contact and the socket contact  10  is maintained. 
     Furthermore, since the part of the socket contact body  13  other than the contact portion  131  is solid, it is possible to secure a cross-sectional area of a current passage, equivalent to that of a large-current socket contact (not shown) which is formed by press work of a plate material, with a smaller size than that of the large-current socket contact. 
     Further, when the part of the socket contact body  13  other than the holes  131 B is formed by cold forging, a continuous state of the metal fibrous structure of the metal material is maintained. Therefore, the strength of the socket contact body  13  is higher than the strength of the electric contact portion  913  of the charging connector terminal  955 , shown in  FIGS. 11 and 12 , which is formed through cutting work which cuts the metal fibrous structure. 
     Furthermore, the front ends of the protruding portions  152  of the spring member  15  do not protrude into the inner space of the contact portion  131  of the socket contact body  13 , and hence when the pin contact is inserted into the contact portion  131 , the protruding portions  152  provide no obstacle to the pin contact, so that there is little fear that the protruding portions  152  are pushed out of the holes  131 B by the pin contact, causing removal of the spring member  15  from the socket contact body  13 . 
     Next, a socket contact body  213  of a socket contact according to a second embodiment of the present invention will be described with reference to  FIGS. 8 to 10 . 
     The same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted. Hereafter, only main differences from the first embodiment will be described. 
     The shape of a connection portion  2132  of the socket contact body  213  according to the present embodiment is different from the shape of the connection portion  132  of the socket contact body  13  according to the first embodiment. An object to be connected to the socket contact according to the second embodiment is a wire (not shown), and the connection portion  2132  is formed into a hollow cylindrical shape such that it can receive one end of the wire therein. The connection portion  2132  includes a wire connection portion  2132 A extending along a central axis thereof. The connection portion  2132  can be formed by cold forging. The spring member  15  of the socket contact  10  according to the first embodiment is used as a spring member of the socket contact according to the present embodiment. 
     The second embodiment provides the same advantageous effects as provided by the first embodiment. 
     Note that although in the above-described embodiments, the spring member  15  has two protruding portions  152 , the spring member  15  is only required to have at least one protruding portion  152 . Further, although the number of the slits  131 A is four, it is only required that at least one slit  131 A is formed. 
     Further, although in the above-described embodiments, the slits  131 A are formed by cold forging, the slits  131 A and the holes  131 B may be formed by removal work, such as cutting, after forming the part of the socket contact body  13  other than the slits  131 A and the holes  131 B by cold forging. 
     Note that although in the above-described embodiments, the holes  131 B, which are circular, are employed as receiving portions for receiving the protruding portions  152  of the elastic annular portion  151 , the holes are not limited to the circular holes  131 B, but they may be rectangular holes. Further, the receiving portions are not limited to holes, but they may be cutouts. 
     Further, although in the above-described embodiments, to secure a larger cross-sectional area of the current passage, the holes  131 E are formed such that they meet the slits  131 A, respectively, the holes  131 B may be formed such that they do not meet the slits  131 A. 
     Note that although in the above-described embodiments, the protruding portions  152  of the spring member  15  are protruding pieces, it is not necessarily required to form the protruding portions  152  as protruding pieces, but they may be formed as protruding portions that protrude from the inner periphery of the elastic annular portion  151  toward the central axis of the elastic annular portion  151 . Further, the protruding portions may be raised portions provided by forming U-shaped slits in the elastic annular portion  151  and bending portions surrounded by the slits such that the surrounded portions are made closer to the central axis of the elastic annular portion  151 . 
     Further, although in the above-described embodiments, the protruding portions  152  are manually bent using the jig, they may be bent using a machine. 
     Note that although in the above-described embodiments, the contact portion  131  has elasticity and the contact pieces  131 C are elastically deformable, the contact portion  131  is not necessarily required to have elasticity. 
     Note that although in the above-described embodiment, the description has been given of the case where the present invention is applied to a large-current socket contact, the present invention may be applied to a socket contact other than the large-current socket contact. 
     It is further understood by those skilled in the art that the foregoing are the preferred embodiments of the present invention, and that various changes and modification may be made thereto without departing from the spirit and scope thereof.