Patent Publication Number: US-7210960-B2

Title: Extension cord and method of manufacturing the same

Description:
FIELD OF THE INVENTION 
   The invention relates to electrical equipments and more particularly to extension cords and manufacturing methods thereof. 
   BACKGROUND OF THE INVENTION 
   Along with worldwide applications of electrical appliances, extension cords become essential components in the electrical appliances, such as sockets and plugs. Conventional sockets and plugs are generally independent components with single function. People must resort to multi-functional socket to satisfy requirements of users when plurals of electrical device need socket at the same time. Furthermore, because conventional socket has its jacks exposed outside and without shield, there is a fear to get an electric shock or have water entry into the socket. 
   Hence, it is desired to provide safe and multi-sectional extension cords to satisfy user&#39;s various requirements. 
   SUMMARY OF THE INVENTION 
   To overcome the drawbacks of prior arts, a main object of the present invention is to provide an extension cord which has a plurality of sockets at intervals along its longitude direction so as to reduce the whole length of extension cord and increase the number of the sockets and thus satisfy various requirements of users. 
   Another object of the present invention is to provide an extension cord which has at least one socket with jacks, wherein the jacks are protected by caps to avoid occurrence of electricity shock and water entry into the socket. 
   The present invention further provides a method of manufacturing such extension cords. 
   To achieve the objects, an extension cord of the present invention comprising: a male plug; at least two conducting wires electrically connecting with the plug; and a plurality of female sockets disposed at intervals along a longitude direction of the conducting wires; each conducting wire electrically connecting with each socket; wherein the plugs and the sockets are both in an integral piece. In the invention, each of the sockets comprises a plurality of caps, springs corresponding to jacks of the socket, and a mooring plate to hold the caps and the springs. A projecting portion is formed on one end of each socket and a socket switch is provided on the projecting portion; a handle is selectively provided on the plug and/or the socket. The socket switch is one of remote switch, time-control switch, light-sensitive control and induction control switch. A switch trip is provided on each socket adjacent to the socket switch. The sockets are shunt-wound, at least one of which has the caps. In an embodiment, the male plug comprises a base portion and a head portion connected with the base portion in a pivot structure. In a further embodiment, the male plug comprises an expansile grounding pin which can be controlled by a handle. 
   A method of manufacturing an extension cord, comprising the steps of: forming a plug; forming a plurality of sockets; forming at least one electrical cords; and disposed the sockets at intervals along a longitude direction of the electrical cord; wherein forming each of the electrical cords comprising: forming at least two electrical wires; and forming an insulated wrap to enclose the conducting wires; the plug and the sockets are all welded by ultrasonic wave to form an integral piece. In the invention, forming the plug comprising the steps of: forming an enclosure constituted by at least two parts; and a plurality of conducting terminals; assembling the parts of the enclosure and the conducting terminals together; welding the above components to form an integral structure by ultrasonic wave. Forming the socket comprises: forming an enclosure constituted by two parts, a face plate and a plurality of conducting terminals; forming a socket switch and a switch trip; assembling the above components together; welding the above components together to form an integral structure by ultrasonic wave. Manufacturing the socket further comprises the steps of: forming a plurality of caps and spring corresponding to jacks of the socket; fixing the caps and the springs on the mooring plate; attaching the caps to the socket. 
   Compared the present invention with the prior arts, an extension cord of the invention comprises a plurality of sockets in series connection or parallel connection with a male plug so as to reduce the total length of conducting wire and increase the number of the sockets, thus satisfying the various requirements of the users. In addition, the caps are provided for the socket to cover the jacks of the socket so as to prevent from electricity shock and water entry into the socket. 
   For the purpose of making the invention easier to be understood, some particular embodiments thereof will now be described with reference to the appended drawings in which: 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of an extension cord according to a first embodiment of the present invention. 
       FIG. 2  is a schematic view of the male plug of the extension cord in  FIG. 1 . 
       FIG. 3  is an exploded, perspective view of the male plug in  FIG. 2 . 
       FIG. 4  is a schematic view of a socket of the extension cord in  FIG. 1  according to a first embodiment of the present invention. 
       FIG. 5  is an exploded, perspective view of the socket in  FIG. 4 . 
       FIG. 6  is an exploded, perspective view of a socket of the extension cord in  FIG. 1  according to a second embodiment of the present invention. 
       FIG. 7  is a schematic view of an extension cord according to a second embodiment of the present invention. 
       FIG. 8  is a schematic view of an extension cord according to a third embodiment of the present invention. 
       FIG. 9  is a schematic view of an extension cord according to a fourth embodiment of the present invention. 
       FIG. 10  is a schematic view of a male plug of an extension cord according to a fifth embodiment of the present invention. And 
       FIGS. 11–12  are schematic views of a male plug of an extension cord according to a sixth embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An extension cord of the present invention comprises a male plug, a plurality of female sockets and conducting wires. Each conducting wire is electrically connected with the male plug in one end and connected with the female socket in the other end. In another embodiment, both ends of each conducting wire are electrically connected with the female sockets that are provided at intervals along a longitude direction of the conducting wire so as to form an extension cord of the invention. 
     FIG. 2  is a schematic view of a male plug of the extension cord of the present invention.  FIG. 3  is an exploded, perspective view of the male plug in  FIG. 2 . In the present invention, as shown in  FIG. 2  and  FIG. 3 , the male plug  1  comprises an enclosure  10 , a plurality of conducting terminals  12  and a cord buckle  14 . The conducting terminals  12  are embedded in the enclosure  10  and extending outwardly from the enclosure  10 . In the present invention, the terminals  12  and the enclosure  10  are in an integral piece. In addition, the plug  1  has its bottom connect with the cord buckle  14  integrally, and the cord buckle  14  has its end connected with the conducting wire  3 , thus connecting the plug  1  and the conducting wire  3  integrally by the cord buckle  14 . 
     FIG. 4  is the schematic view of the socket of the extension cord in  FIG. 1  according to a first embodiment of the present invention;  FIG. 5  is the exploded, perspective view of the socket in  FIG. 4 . As shown in  FIG. 4  and  FIG. 5 , in female sockets according to a first embodiment of the present invention, the socket  4  comprises a face plate  40  and a housing  41 . A plurality of throughholes  400  are provided on the face plate  40 , and the plurality of the conducting terminals  12  (shown in  FIG. 3 ) of the male plug  1  are provided corresponding to the throughholes  400  of the male plug  4 . The face plate  40  and the housing  41  are disassembled integral pieces. 
   In the embodiment as shown in  FIG. 5 , the socket  4  also includes a plurality of caps  42 , a plurality of spring  401  and a mooring plate  43 , hardware terminals  44  and a cord buckle  45 . The caps  42 , springs  401 , the mooring plate  43 , the hardware terminals  44  are all held in a cavity of the female socket  4 . Among them, the caps  42  and the springs  401  are arranged corresponding to the throughholes  400 . Each spring  401  is mounted on the cap  42 . The caps  42  and the springs  401  can be selectively moved to seal or open the throughholes  400 . A plurality of throughholes  430  is formed on the mooring plate  43  corresponding to the throughholes  400  on the face plate  40 . The caps  42  and the springs  401  are fixed on the bottom of the face plate  40  by the mooring plate  400 . The hardware terminals  44  are provided corresponding to the throughholes  430  on mooring plate  43 , thus making the terminals of the male plug extend through the throughholes  400  on the face plate  40  and the throughholes  430  on the mooring plate  43  in turn, and then be inserted in slots of the hardware terminals  44 . The hardware terminals  44  comprise ground wire terminal, neutral wire terminal and live wire terminal. The cord buckle  45  is integrally connected with the bottom of the socket  4 . 
   Referring to  FIGS. 1–5 , during operation, the terminals  12  of the male plug  1  are inserted into the throughholes  400  of the female socket  4  to push the caps  42  to compress the springs, so as to make it contact with the hardware terminals  44  in the female socket  4 , thus an electrical connection between the male plug  1  and the female socket  4  is attained. When the extension cord is pulled out, the caps  42  moves back under the relapse strength of the springs to seal the throughholes  430  on the mooring plate  43 , so avoiding occurrence of electricity shock and water entry into the socket. 
     FIG. 6  is an exploded, perspective view of a second embodiment of the male plug of the extension cord of the present invention. In the embodiment as shown in  FIG. 6 , the female socket  2  comprises a face plate  20  and an enclosure  21 , and a plurality of throughholes  200  are arranged on the face plate  20 , a plurality of conducting terminals  12  of the male plug  1  are arranged corresponding to the plurality of throughholes  200  of the female socket  2 . The face plate  20  and the shell  21  are integrally formed. 
   Referring to  FIG. 6 , the female socket  2  also includes a plurality of springs  22 , a plurality of caps  23 , a mooring plate  25 , hardware terminals  24  and a plurality of cord buckles  26 . Among them, the springs  22 , the caps  23 , the mooring plate  25  and the hardware terminals  24  are all held in cavity of the female socket  2 . The springs  22  and the plurality of caps  23  are arranged corresponding to the plurality of throughholes  200 , each of the springs  22  is disposed on the cap  23 . The springs  22  and the caps  23  can be selectively moved to seal or open the throughholes  200 . A plurality of throughholes  240  are formed on the mooring plate  25  corresponding to the throughholes  200  of the face plate  20 . The springs  22  and the plurality of caps  23  are fixed on the back of the face plate  20  by the mooring plate  25 . The hardware terminals  24  are provided corresponding to the throughholes  240  of the mooring plate  25 , thus making the terminals of the male plug get through the throughholes  200  on the face plate  20  and the throughholes  240  on the mooring plate  25  in turn, and then be inserted in a slot of hardware terminals  24 . The hardware terminals  24  comprise a ground wire terminal, a neutral wire terminal and a live wire terminal. The cord buckle  26  and bottom of socket  2  are integrally formed. 
   Furthermore, in the embodiment, the female socket  2  further includes a socket switch  202  and a switch trip  27 . The socket switch  202  is provided on the face plate  20  for controlling the electrical connection between the male plug  1  and the female socket  2 . The switch trip  27  is provided in a cavity constituted by the face plate  20  and the enclosure  21 . The socket switch  202  and the switch trip  27  can contact in discontinuity. The principle of electrical operation of the female socket  2  is similar to that of the female socket  4 , so a detailed description is omitted herefrom. The only difference between the female socket  4  and the female socket  2  is that the socket  2  further includes the socket switch  202  and the switch trip  27 . When power source is required to switch-on, it is only required to insert the male plug  1  into the female socket  2  firstly, and then press down the socket switch  202  to push the switch trip  27  downwardly, thus an electrical connection between the male plug  1  and the female socket  2  is completed. When the power source is required to switch-off, it is only required to press down the socket switch  202  again, then the electrical connection between the male plug  1  and the female socket  2  will be cut off so as to protect the female socket on occasion of forgetting to pull the male plug out. 
   It can be understood that the socket switch of the invention can be optional among remote switch, time-control switch, light-sensitive control and induction control switch. 
   To facilitate pulling the male plug out of the female socket, a handle can be provided on the male plug and the female socket, it can achieve the effect of laborsaving and electricity proof for the user to pull out male plug through holding the handle of male plug or female socket. 
   A method of manufacturing an extension cord of the invention comprises the following steps: firstly, forming a plug  1 , a socket  2  and at least an electrical cords; secondly, provided a plurality of sockets  2  at intervals along a longitude direction of the electrical cord; and lastly, welding the plug  1  and the socket  2  to form an integral structure thereof by ultrasonic wave. In the invention, forming each electrical cord includes forming at least two conducting wires and an insulated wrap to enclose the conducting wires. 
   In one embodiment of the invention, a method of manufacturing the male plug  1  includes the following steps: first, forming an enclosure  10  constituted by at least two parts and a plurality of conducting terminals  12 ; then, assembling the parts of the enclosure  10  and the conducting terminals  12  together; lastly, welding the above components to form an integral structure by ultrasonic wave. 
   A method of manufacturing the socket  2  comprises the following steps: first, forming an enclosure  21  constituted by two parts, a face plate  20  and a plurality of hardware terminals  24 ; next, forming a socket switch  202  and a switch trip  27 ; then assembling the above components together; lastly, welding the above components together to form an integral structure by ultrasonic wave. 
   In another embodiment of the invention, a step of manufacturing a socket  2  with caps  23  further comprises the steps of: forming a plurality of caps  23  and spring  22  corresponding to the throughholes  200  of the socket  2  firstly; secondly, fixing the caps  23  and the springs  22  on the mooring plate  25 ; lastly, attached them into the socket  2 . 
   An extension cord of the invention can be assembled by the aforementioned male plugs and female sockets or conventional male plugs and female sockets, the invention will be illustrated through the following embodiments. 
   THE FIRST EMBODIMENT 
     FIG. 1  is a schematic view of a first embodiment of the extension cord of the present invention. As shown in  FIG. 1 , in a first embodiment of the invention, an extension cord of the present invention comprises a male plug  1 , a plurality of female sockets  2 ,  4  and a plurality of conducting wires  3 . A sectional conducting wire  3  is electrically connected with the male plug  1  in one end and connected with the female socket  2  in the other end; the female sockets  2  and  4  are provided at intervals along a longitude direction of the conducting wire  3  to form an extension cord of the invention. 
   THE SECOND EMBODIMENT 
     FIG. 7  is a schematic view of a second embodiment of the extension cord of the present invention. As shown in  FIG. 7 , in the second embodiment of the invention, an extension cord comprises a male plug  1 , female sockets  2 ,  112 ,  112  and a plurality of conducting wires  3 . Similar to the first embodiment shown in  FIG. 1 , the female socket  2  and two other sockets  112  are provided along a longitude direction of the conducting wire  3 , which is electrically connected to each female socket. Obviously, the numerals and kinds of the sockets are not limited to the embodiments in the invention. It can be achieved that electrical coupling of several female sockets only by connecting a male plug with power source. 
   THE THIRD EMBODIMENT 
     FIG. 8  is a schematic view of a third embodiment of the extension cord of the present invention. As shown in  FIG. 8 , an extension cord comprises a male plug  1 , a plurality of female sockets  2 ,  112 ,  113  and a plurality of the conducting wires  3 . In the embodiment, the connecting method of the plug with the sockets is similar to that of the first and second embodiment. The sockets are provided at intervals along the length of the conducting wire  3 . The plurality of conducting wires are educed from one female socket to make series connection or parallel connection for the several female sockets, thus reducing the whole length of the conducting wires and increasing the number of female sockets. 
   THE FOURTH EMBODIMENT 
     FIG. 9  is a schematic view of a fourth embodiment of the extension cord of the present invention. As shown in  FIG. 9 , an extension cord comprises a male plug  1 , a plurality of female sockets  4 ,  2 ′,  2 ′ and a plurality of conducting wires  3 . In this embodiment, caps  22 ′ are provided on each female socket  2 ′. The caps  22 ′ are connected with the body of the female socket  2 ′ by connecting bars  20 ′. When the female socket is not in use, the caps  22 ′ can be shut to protect the jacks of the female socket  2 ′, thus avoiding occurrence of electricity shock and water entry into the socket. 
   THE FIFTH EMBODIMENT 
     FIG. 10  is a schematic view of a fifth embodiment of the present invention. As shown in  FIG. 10 , a male plug  1 ′ of the invention comprises a base portion  800  and a head portion  802  connected with the base portion  800  in a pivot structure  801  so that the head portion  802  can be rotated in the pivot structure  801 , which is as a pivot relative to the base portion  800 . 
   THE SIXTH EMBODIMENT 
     FIGS. 11–12  are schematic views of a sixth embodiment of the present invention. As shown in  FIGS. 11–12 , the male plug  1 ″ comprise an expansile grounding pin  900  which can be controlled by a handle  901 . In the embodiment, the grounding pin  900  comprises a terminal portion  910  and a connection portion  911 . When the handle  901  is rotated, it will drive the terminal portion  910  to press the connection portion  911 , and then the connection portion  911  expands under the pressure of the terminal portion  910 . Thus, when the male plug  1 ″ is inserted into a socket, a firm engagement therebetween will be attained by rotating the handle  901 . 
   It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.