Patent Publication Number: US-7896663-B2

Title: Plug assembly, attachment plug and conversion plug

Description:
FIELD 
     The present invention is related to a plug assembly formed by an attachment plug and a conversion plug, and to the attachment plug and the conversion plug forming the plug assembly. 
     BACKGROUND 
     In the world, there are many kinds of outlets having different specifications, i.e., receptacles of different shapes. In a case where products for export are manufactured, each product is provided with a plug suitable for the specification of the product&#39;s destination, or each product is provided with a conversion plug as disclosed in U.S. Pat. No. 5,613,863 or Japanese Laid-open Patent Publication No. 2007-52998 at the time of shipment. 
     Here, when a plug manufacturer produces plugs, it is cost-effective to assemble: a plug suitable for the specification of one kind of outlet; and a conversion plug used as an adaptor of the plug and suitable for another kind of outlet, rather than separately producing each plug for the specification of a suitable outlet. This is because the attachment plug usually has various circuits including an AC-DC conversion circuit and an overcurrent prevention circuit and thus, in many cases, the cost as a whole is reduced by mounting such circuits on only an attachment plug of one kind and making a conversion plug serve only for the purpose of supporting an outlet of different specification. 
     Therefore, in such a system that a plug assembly is exported after being formed by securely coupling an attachment plug and a conversion plug to each other, the plug assembly can be provided at a lower cost. 
     Here, when forming a plug assembly composed of an attachment plug and a conversion plug, the following are important. Blades and the like to be inserted into an outlet should be protected from unintentional force applied thereto without, extra caution when the conversion plug is inserted into the attachment plug. Also, after the conversion plug is coupled to the attachment plug, the conversion plug and the attachment plug should be so integrated that there is no backlash or play between the coupled attachment plug and conversion plug, thereby preventing deformation of the blades. 
     SUMMARY 
     The present invention has been made in view of the above circumstances and provides a plug assembly having a structure in which blades are hardly deformed both during assembly and when in use and also provides an attachment plug and a conversion plug forming the plug assembly. 
     A plug assembly according to the present invention includes: 
     an attachment plug that includes a pair of blades projecting while facing each other and plugged in an outlet of a first specification, a plug main body having a storage channel for housing the pair of blades, and a blade support that supports one end of each of the pair of blades and is pivotably supported by the plug main body to rotate, along a plane including the pair of blades by approximately 90 degrees, between a stand state in which the pair of blades stand from the plug main body and a stored state in which the pair of blades are engaged in the storage channel; and 
     a conversion plug that includes a plurality of insert projections plugged in an outlet of a second specification different from the first specification and a pair of recesses into which the pair of blades in the stand state are inserted, the insert projections carrying electricity received from the outlet of the second specification to the pair of blades when the pair of blades are inserted into the pair of recesses and, 
     wherein the conversion plug further includes a pair of guide projections that hold therebetween the pair of blades in the stand state when the conversion plug is coupled to the attachment plug and guide the pair of blades into the pair of recesses, and 
     wherein the plug main body has, at positions respectively adjacent to the pair of blades in the stand state, a pair of storage recesses for housing the pair of guide projections. 
     In the plug assembly according to the present invention, when an operator assembles a plug assembly by attaching a conversion plug to an attachment plug, the pair of guide projections hold therebetween the pair of blades and naturally guide them into the pair of recesses. Thus, at the time of assembly, the guide projections restrict a posture of the pair of the blades and prevent unnecessary force from being applied to the blades, thereby preventing deformation of the blades. 
     In addition, when in use, the guide projections are accommodated in the recesses and function as a protection wall by covering the blades. Thus, the blades are protected from possible impact caused by fall or collision, thereby preventing deformation of the blades when in use after assembly. 
     Here, preferably, the storage channel is also used as one of the pair of the storage recesses. 
     This additional feature simplifies the structure of the attachment plug of the plug assembly, which enables further reduction in cost. 
     Further, preferably, the conversion plug and the plug main body have a conversion-plug engagement section and a plug-main-body engagement section, respectively, which engage with each other when the conversion plug is coupled to the attachment plug. 
     According to this preferable feature, when the conversion plug is coupled to the attachment plug, the conversion plug and the plug main body of the attachment plug are securely connected to each other with the conversion-plug engagement section and the plug-main-body engagement section, so that a robust structure is achieved. 
     Also, the attachment plug of the plug assembly according to the present invention is an attachment plug that includes: 
     a pair of blades projecting while facing each other and plugged in an outlet of a first specification; 
     a plug main body having a storage channel for housing the pair of blades; and 
     a blade support that supports one end of each of the pair of blades and is pivotably supported by the plug main body to rotate, along a plane including the pair of blades by approximately 90 degrees, between a stand state in which the pair of blades stand from the plug main body and a stored state in which the pair of blades are engaged in the storage channel, 
     wherein the attachment plug is engaged with a conversion plug that has a plurality of insert projections plugged in an outlet of a second specification different from the first specification, a pair of recesses into which the pair of blades in the stand state are inserted, and a pair of guide projections that hold therebetween the pair of blades in the stand state when the conversion plug is coupled to the attachment plug and guide the pair of blades into the pair of recesses, and when the plurality of insert projections are plugged in the outlet of the second specification in a state in which the pair of blades are inserted into the pair of recesses, the insert projections carry electricity received from the outlet of the second specification to the pair of blades, and 
     wherein the plug main body has, at positions respectively adjacent to the pair of blades in the stand state, a pair of storage recesses for housing the pair of guide projections. 
     Also, the conversion plug of the plug assembly according to the present invention is a conversion plug attached to an attachment plug that has a pair of blades projecting while facing each other and plugged in an outlet of a first specification, a plug main body having a storage channel for housing the pair of blades, and a blade support that supports one end of each of the pair of blades and is pivotably supported by the plug main body to rotate, along a plane including the pair of blades by approximately 90 degrees, between a stand state in which the pair of blades stand from the plug main body and a stored state in which the pair of blades are engaged in the storage channel, the conversion plug receiving electricity from an outlet of a second specification different from the first specification and carrying the electricity to the pair of blades, the conversion plug including: 
     a plurality of insert projections plugged in an outlet of a second specification different from the first specification, a pair of recesses into which the pair of blades in the stand state are inserted, and a pair of guide projections that hold therebetween the pair of blades in the stand state when the conversion plug is coupled to the attachment plug and guide the pair of blades into the pair of recesses. 
     As described above, the present invention is capable of realizing a plug assembly at a low cost having a structure in which blades are hardly deformed both during assembly and when in use and an attachment plug and a conversion plug forming the plug assembly. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating plural kinds of conversion plugs  11 ,  11 A, and  11 B to be plugged in outlets respectively having different specifications, and an attachment plug  10  for use in Japan; 
         FIGS. 2A and 2B  are diagrams each illustrating an external appearance of the attachment plug  10 ; 
         FIG. 3  is a diagram illustrating external appearances of the attachment plug  10 ; 
         FIG. 4  is a diagram illustrating external appearances of the attachment plug  10 ; 
         FIG. 5  is a diagram illustrating a structure of the conversion plug  11 ; 
         FIG. 6  is a diagram illustrating the structure of the conversion plug  11 ; 
         FIG. 7  is a diagram illustrating the structure of the conversion plug  11 ; 
         FIG. 8  is a diagram illustrating the structure of the conversion plug  11 ; 
         FIG. 9  is a diagram illustrating a plug assembly  1 ; 
         FIG. 10  is a diagram illustrating the plug assembly  1  depicted in  FIG. 9  as viewed from a side where plural projections  111  of the conversion plug are provided; 
         FIG. 11A  and  FIG. 11B  are diagrams illustrating internal structures before the conversion plug  11  is inserted into a plug main body  100  of the attachment plug  10  to form the plug assembly  1 ; and 
         FIG. 12A  and  FIG. 12B  are diagrams illustrating internal structures after the plug assembly  1  is formed by inserting the conversion plug  11  into the plug main body  100  of the attachment plug  10 . 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereafter, an embodiment of the present invention will be described with reference to the attached drawings. 
       FIG. 1  illustrates plural kinds of conversion plugs  11 ,  11 A, and  11 B to be plugged in outlets respectively having different specifications, and an attachment plug  10  for use in Japan. The conversion plugs  11 ,  11 A, and  11 B are suitable respectively for the specifications of three different destinations. Any of the conversion plugs  11 ,  11 A, and  11 B is inserted into, coupled to, and fixed to the attachment plug  10  for use in Japan to form a plug assembly. Hereinafter, the attachment plug  10  will be described as an attachment plug to be plugged in an outlet having a first specification for use in Japan, while the conversion plug  11  will be described as a conversion plug to be plugged in an outlet having a second specification. 
     At first, description will be made on the attachment plug  10  for use in Japan that is an example of the attachment plug of the present invention, which is to be plugged in an outlet having the first specification. 
       FIGS. 2A to 4  illustrate external appearances of the attachment plug  10 . 
       FIG. 2A  illustrates a pair of blades  101  in an erected state, while  FIG. 2B  illustrates the pair of blades  101  in a state of being housed in a storage channel  102 .  FIG. 3  illustrates a top view and a side view of the attachment plug  10  depicted in  FIG. 2A .  FIG. 4  illustrates a top view and side views of the attachment plug  10  depicted in  FIG. 2B . 
     More specifically,  FIG. 2A  illustrates the attachment plug  10  to be plugged in an outlet having the first specification, i.e., the Japanese specification, having the pair of blades  101  facing each other in the erected state. 
     Further, the attachment plug  10  has a plug main body  100  in which the storage channel  102  is formed for housing the pair of blades  101  as illustrated in  FIG. 3 . The pair of blades  101  are supported by a blade support  103  as illustrated in  FIG. 4 , which supports one end of each of the blades  101  and is pivotably supported on the plug main body  100 . 
     Thus, the pair of blades  101  swivel by 90 degrees, along a plane including the pair of blades  101 , between the erected state (see  FIG. 2A ) and the state of being housed in the storage channel  102  (see  FIG. 2B ). 
     In addition, the storage channel  102  illustrated in  FIG. 3  also serves as a recess  102 B that is one of the pair of recesses for storage according to the present invention. The other recess  102 A is formed on the other side across the pair of blades  101 . When the conversion plug  11 , which will be described later, is inserted into the attachment plug  10  to form a plug assembly, guide projections of the conversion plug  11  are respectively housed in the recesses  102 A and  102 B. In the present embodiment, there is described an example in which the structure of a plug assembly is simplified by using the storage channel  102  serving also as the recess  102 B that is one of the pair of the recesses. 
     In addition, in order to secure engagement with the conversion plug  11 , the plug main body  100  of the attachment plug  10  has a recess  104  (see  FIG. 2A  to  FIG. 4 ) for retaining a projection  114  (see  FIG. 5 ) formed in the conversion plug  11 , which will be described later in detail. The recess  104  corresponds to an example of the plug-main-body engagement section of the plug main body according to the present invention. Incidentally, the plug main body  100  further has another recess, which will be described later in detail. This recess is a recess  105  provided at a sidewall of the storage channel  102  of the plug main body  100 . The recess  105  shares the same concave with the storage channel  102  so that the structure is simplified. 
     Next, a structure of the conversion plug  11  illustrated in  FIG. 1  will be described. The other conversion plugs  11 A and  11 B each have a structure similar to that of the conversion plug  11 . 
       FIGS. 5 to 7  illustrate the structure of the conversion plug  11 .  FIG. 8  illustrates a state before the conversion plug  11  is inserted into the attachment plug  10 .  FIG. 9  illustrates a plug assembly  1  after the conversion plug  11  is inserted into the attachment plug  10 . 
       FIG. 5  is a perspective view of the conversion plug  11  viewed from the attachment plug  10  into which the conversion plug  11  is to be inserted.  FIG. 6  illustrates in the center thereof a front view of the conversion plug  11  in a state in which projections  111  are provided on a side. A left side view and a right side view are illustrated on both sides of the front view. Further, under the right side view, illustrated is a side view of the conversion plug  11  depicted in the right side view.  FIG. 7  illustrates a rib  116  that is an element of the internal structure of the conversion plug  11 . 
     Further,  FIG. 8  illustrates that the plug assembly  1  is assembled when the conversion plug  11  illustrated in  FIGS. 5 to 7  is inserted into the attachment plug  10 .  FIG. 9  illustrates the plug assembly  1  after the conversion plug  11  is coupled to the attachment plug  10 . 
     The conversion plug  11  has, on one side thereof, plural insert projections  111  to be inserted into an outlet having a second specification that is different from the first specification. On the other side opposite to the one side where the projections  111  are provided, the conversion plug  11  has a pair of recesses  112  into which the pair of blades  101  in the erected state of the attachment plug  10  are to be inserted. By inserting the pair of blades  101  into the pair of recesses  112 , the conversion plug  11  is coupled to the attachment plug  10 . 
     Hereafter, the structure of the conversion plug  11  that is a feature of the present invention will be described in detail, referring to  FIGS. 5 to 7 . 
     As illustrated in  FIGS. 5 to 6 , the conversion plug  11  has guide projections  113  that hold the pair of blades  101  in the erected state interposed therebetween and guide them into the pair of recesses  112  at the time when the conversion plug  11  is coupled to the attachment plug  10 . Each of the guide projections  113  has such a tapered shape that its tip is narrower than its root. For this reason, the respective opposed faces of the pair of guide projections  113  are slanted instead of being parallel to each other, and the space between the respective tips of the pair of guide projections  113  is wider than the space between the respective roots thereof. 
     The guide projections  113  restrict the attitude of the blades  101  when the conversion plug  11  is inserted into the attachment plug  10 , and thus naturally guide the blades  101  of the attachment plug  10  to the recesses  112  formed in the conversion plug  11 . This structure almost completely prevents exertion of unnecessary force on the blades  101  when the conversion plug  11  is coupled to the attachment plug  10  by an operator. Further, since the space between the respective tips of the pair of guide projections  113  is wide, the blades  101  of the attachment plug  10  are readily positioned between the pair of guide projections  113  and guided to the appropriate positions as the blades  101  are inserted, which reduces backlash. 
     As illustrated in  FIG. 3 , the plug main body  100  has the recesses  102 A and  102 B formed in positions respectively adjacent to the pair of blades  101  in the erected state. The recesses  102 A and  102 B accommodate the pair of guide projections  113  of the conversion plug  11  illustrated in  FIGS. 5 and 6 . 
     Thus, after the conversion plug  11  is coupled to the plug main body  100  of the attachment plug  10 , the guide projections  113  are accommodated in the recesses  102 A and  102 B so that the guide projections  113  cover and protect the pair of blades  101 . As a result, the guide projections  113  reinforce the strength in the periphery of the blades  101  by serving as a wall, thereby preventing deformation of the blades  101  even when external force is applied thereto due to fall or collision. 
     When the conversion plug  11  is unexpectedly disengaged from the attachment plug  10 , the pair of guide projections  113  prevent another product&#39;s blades in the same shape as that of the pair of the blades  101  from being wrongly inserted into the conversion plug  11 . Thus, in addition to the guiding and protecting functions described above, the guide projections  113  have the function of preventing a failure by unexpected use. 
     Further, a case  110  of the conversion plug  11  is formed by elastic resin or the like as illustrated in  FIG. 5  and has the projection  114  and a projection  115  formed in two separate positions thereof that are respectively engaged in the recess  104  (see  FIG. 3 ) and the recess  105  formed in the plug main body  100  of the attachment plug  10 . When the projections  114  and  115  are engaged in the recesses  104  and  105  formed in the plug main body  100  of the attachment plug  10  with elastic deformation, the conversion plug  11  is firmly coupled to the plug main body  100  of the attachment plug  10 . The projection  115  is provided on an extension line of the line along the direction in which the pair of guide projections  113  are aligned. Also, corresponding to this projection  115 , the recess  105  illustrated in  FIG. 3  is provided on an extension line of the line along the direction in which the pair of guide projections  113  are aligned. Therefore, even when a twisting force is exerted in a state that the conversion plug  11  is coupled to the attachment plug  10 , deformation of the blades  101  and removal of the attachment plug  10  are prevented. The projections  114  and  115  are examples of the conversion-plug engagement section according to the present invention. 
     Further, the case  110  of the conversion plug  11  is provided with a surrounding part  117  that surrounds the projection  114  and a surrounding part  118  that surrounds the projection  115 . The surrounding part  117  has a jig insertion part  117   h  formed by an indentation, while the surrounding part  118  has a jig insertion part  118   h  as illustrated in  FIG. 6 . The details of the jig insertion parts  117   h  and  118   h  will be described later. 
     Furthermore, as illustrated in  FIG. 7 , the rib  116  is formed inside the conversion plug  11 . The rib  116  serves as a partition to prevent short circuit of the two parallel projections  111  that are conductive members to receive electricity. 
     In this way, the conversion plug  11  is coupled to the attachment plug  10  so that they form the plug assembly  1  as illustrated in  FIG. 9 . 
     According to the structure illustrated in  FIG. 9 , as compared with the technique disclosed in U.S. Pat. No. 5,613,863, the amount of deviation of the conversion plug  11  toward one side of the attachment plug  10  is suppressed to be small so that the attachment plug  10  and the conversion plug  11  are integrated. Thus, even if the plug assembly  1  illustrated in  FIG. 9  is dropped or hit against a wall when in use, moment applied to the pair of blades  101  of the attachment plug  10  is suppressed to be small, thereby preventing deformation of the blades  101 . 
     Lastly, there will be described a structure of an engagement section that reinforces coupling between the conversion plug  11  and the attachment plug  10  after the conversion plug  11  is coupled to the attachment plug  10 . In addition, a structure of a conductive section that carries electricity from an outlet having a different specification to the pair of blades  101  will also be described. 
       FIG. 10  illustrates the plug assembly  1  depicted in  FIG. 9  as viewed from the side where the plural projections, i.e., the three projections  111  according to the present embodiment, of the conversion plug  11  are provided.  FIG. 10  also illustrates lines A-A and B-B for taking cross-sectional views. 
       FIG. 11A  and  FIG. 11B  illustrate internal structures of the conversion plug  11  and the attachment plug  10  before the conversion plug  11  is coupled to the plug main body  100  of the attachment plug  10  to form the plug assembly  1 .  FIG. 11A  illustrates a cross-sectional view taken along the line A-A and  FIG. 11B  illustrates a cross-sectional view taken along the line B-B. 
       FIG. 12A  and  FIG. 12B  illustrate internal structures of the conversion plug  11  and the attachment plug  10  after the plug assembly  1  is formed by inserting the conversion plug  11  into the plug main body  100  of the attachment plug  10 . 
       FIG. 12A  illustrates a cross-sectional view taken along the line A-A and  FIG. 12B  illustrates a cross-sectional view taken along the line B-B. 
     Firstly, by referring to the cross-sectional view taken along the line A-A and the cross-sectional view taken along the line B-B as well as  FIGS. 11A and 12A , the internal states of the conversion plug  11  and the attachment plug  10  before the plug assembly  1  is assembled will be described. 
     As illustrated in  FIGS. 11A and 12A , one side (the upper side in the drawing) of the conversion plug  11  has the projections  111  to be inserted into an outlet having a second specification, and the other side (opposite to the side where the projections are provided) of the conversion plug  11  has the recesses  112  into which the pair of blades  101  of the attachment plug  10  are inserted. The plug assembly  1  is assembled by inserting the pair of blades  101  of the attachment plug  10  into the recesses  112 . 
     The conversion plug  11  and the plug main body  100  of the attachment plug  10  respectively have the projections  114 ,  115  and the recesses  104 ,  105  that are mutually engaged when the conversion plug  11  is coupled to the attachment plug  10 . The projections  114 ,  115  are examples of the conversion-plug engagement section according to the present invention, and the recesses  104 ,  105  are examples of the plug-main-body engagement section of according to the present invention. Before the conversion plug  11  is coupled to the attachment plug  10 , no change appears in these projections and recesses as illustrated in  FIGS. 11A and 11B . In addition, in the states illustrated in  FIGS. 11A and 11B , there is no change in the conductive members  111   a  of the conversion plug  11 , which extend from the plural projections  111  toward the inside of the conversion plug  11 , and in the blades  101  of the attachment plug  10 . In other words, the conductive members  111   a  are not in contact with the blades  101 . 
     Subsequently, when the conversion plug  11  is inserted into the attachment plug  10  by an operator to assemble the plug assembly, the blades  101  are naturally guided by the guide projections  113  to the recesses  112  as described above. When the conversion plug  11  is completely inserted into the attachment plug  10  by the operator, the conversion plug  11  and the attachment plug  10  are securely coupled to each other as illustrated in  FIGS. 12A and 12B . 
     When the conversion plug  11  is completely inserted into the attachment plug  10  in this way, as illustrated in  FIGS. 12A and 12B , the projections  114 ,  115  of the conversion plug  11  are respectively engaged in the recesses  104 ,  105  of the attachment plug  10  so that the conversion plug  11  and the plug main body  100  of the attachment plug  10  are firmly coupled to each other. 
     Further, during the process in which the conversion plug  11  is inserted into the attachment plug  10 , the conductive members  111   a  in a plate-spring shape are pushed to be separated from each other outwardly as the blades  101  are inserted further into the recesses  112 . When the blades  101  are fully inserted into the recesses  112 , the plate-spring-shaped conductive members  111   a  contact the sides of the blades  101  while pushing these sides to carry electricity from the outlet having the second specification to the blades  101 . The plug assembly  1  is assembled in this manner. 
     The plug assembly  1  assembled in the manner as described above almost completely prevents deformation of the blades  101  even when a user drops the plug assembly during use, for the following two reasons: the guide projections  113  protect the blades  101 ; and the amount of deviation of the conversion plug  11  with respect to the plug main body  100  of the attachment plug  10  is suppressed to be small so that the conversion plug  11  and the attachment plug  10  are integrated. 
     Further, in the plug assembly  1  after being assembled, as illustrated in  FIG. 9 , the projections  114  and  115  are covered with the surrounding parts  117  and  118  and the conversion plug  11 . At the time of repair, engagement of the projections  114  and  115  in the recesses  104  and  105  is released by inserting a thin-stick-like jig into the jig insertion parts  117   h  and  118   h . This avoids such a situation that the attachment plug  10  is disengaged from the conversion plug  11  due to an intentional touch on the projections  114  and  115  by a user. 
     As described above, it is possible to realize, at low cost, a plug assembly having blades that are free from deformation both during assembly and when in use, and an attachment plug and a conversion plug forming the plug assembly.