Patent Publication Number: US-6981888-B2

Title: Lockable electric power cord adapter

Description:
RELATED APPLICATIONS 
   This application is a divisional application claiming priority to application Ser. No. 10/881,918, filed Jun. 30, 2004, U.S. Pat. No. 6,875,040, which claims priority to U.S. Provisional Application Ser. No. 60/535,243, filed Jan. 9, 2004. 

   FIELD OF THE INVENTION 
   This invention relates to electrical power connectors and more particularly, to an adapter for receiving and locking to a male electrical power plug. 
   BACKGROUND OF THE INVENTION 
   In conventional North American electrical connectors, a female plug receptacle is designed or adapted to receive a male plug having two straight prongs, and, usually, a grounding pin. The male plug prong may be polarized, in accordance with standard practice, or they may be of the same size. 
   When such a connection is made, there exists the possibility that, when longitudinal stress is applied thereto, the male and female connectors may disconnect. This is especially true where one of the connectors, usually the female, is one end of an extension cord, or where, for example, the cord is an elongated attachment to a power tool and is terminated by a male plug. In such case, the disconnect is a nuisance at the very least, and potentially dangerous where power to the tool or other device is essential. Thus, for example, if the powered equipment is a hedge trimmer or lawn mower, it is necessary to stop the work to make a re-connect to the power source, which is usually terminated at its cord end with a female plug. In some cases, the disconnect may not be complete, and the prongs are slightly bared but power is still being transmitted, a real danger of electric shock can be created, especially where the grass or ground is damp. 
   It has been recognized in the prior art that these problems exist, and numerous arrangements have been proposed for overcoming them, substantially all such arrangements having a locking mechanism for locking the power source cord, usually terminated in a standard female connector to the power receiving tool or cord, terminated in a male connection. The standard North American male plug connector has, as pointed out hereinbefore, two flat, parallel blades, each of which has a small diameter hole spaced from the plug face at a set distance, or a small range of distance. It is a feature of most of the prior art arrangements that some means is provided for anchoring the female member terminating the power source cord to one or both of the holes. 
   In U.S. Pat. No. 5,921,797 of Forrester such an arrangement is shown wherein the female plug includes a mechanism for locking the connectors together by releasably engaging the holes in the male member blades. The female portion of the connector comprises a two part housing and a cap therefor which is bolted to the housing, with movable actuating and locking collars between the cap and the housing. The assembly is quite complex, with an extremely large member of individual parts, at least ten of which are movable in connecting and disconnecting the male plug therefrom. The extensive list of parts requires columns 2, 3, and 4 of the patent, and serves to emphasize the complexity of the structure. 
   There are numerous other prior art arrangements which depend upon engagement of the holes in the male prongs to lock the male plug to the female receptacle. See, for example, U.S. Pat. Nos. 4,319,797 of Qtaui et al., 4,932,886 of Glaser, and 5,286,213 of Altergott et al. In most prior art mechanism, the female plug terminating the power cord itself has the locking mechanism therein, and thus the arrangement is not adaptable to other power cord arrangements, such as connection of an extension cord between the power source cord and the cord of the power consuming mechanism or tool. 
   SUMMARY OF THE INVENTION 
   The principles and features of the present invention are illustrated hereinafter as used in a North American type assembly. It is to be understood, however, that other types of plugs, such as continental, may be adapted to use these principles and features. 
   The present invention is, basically, an adapter having a unitary, hollow housing and a cap therefor, mounted on one end of the housing, wherein the cap is a female member for receiving a male plug such as that connected to a tool, and the other end of the housing has extending therefrom male blade members, including a grounding prong, for attachment to the female terminated power cord. 
   Within the housing are mounted first and second blade receiving members for receiving the blades of the male connector. Pivotally mounted on each of the blade receiving members is a locking member having a barbed end which is adapted to pass through an opening in one side of the blade receiving member and engage the hole in the male member blade. An actuator which is mounted in a slot in the housing and has an external surface for hand or thumb actuation to slide the member rearwardly from its normal spring biased position. The actuating member has first and second spaced lugs thereon, each of which is adapted to engage a surface or edge of one of the pivotable members. The surface to be engaged has a sloped portion and a stop member. When the actuating member is in its normal, spring biased position, the lugs thereof engage the stop members to hold the locking members in the blade engaging locked position, with the spring maintaining the engagement. When the actuating member is manually pushed toward the rear, the lugs thereon engage the sloped surfaces and cam the pivotable locking members into an open or unlocked position, permitting removal of the male plug. When released, the actuator moves back due to the spring force and hence against the stops on the locking members, holding them, by spring force alone, in a closed or locking position. 
   It can be seen from the foregoing that the locking adapter is quite simple, having only three moving parts as compared to the large number of parts in, for example, the Forrester &#39;799 patent. Further, for that reason, the adapter of the invention can be quickly and quite easily assembled and disassembled. 
   The basic adapter, as just described, can be adapted to be a female cord termination by removing the standard ferrule plug from the cord, stripping the wires and connecting them as by soldering to the male blades which project from the end of the adapter, and encasing the connections in a plastic cover. The adapter has first and second bosses, one on either side, having openings therein for receiving plastic or other suitable material straps which extend rearwardly. A split collar is mounted on the cord and has a split insert which bears against the distal end of the plastic cover and has slits therein for receiving the straps. A bolt is used to tighten the split cover and the insert, thereby gripping the straps extending therebetween. With this arrangement, the connections are protected from external stresses and the adapter remains firmly mounted to the power cord. 
   In still another embodiment, instead of the straps, the connections of the cord to the adapter are completely encased in a plastic, or other suitable material, overmolded casing, thereby mounting the adapter permanently to the cord. 
   These and other features and principals of the invention will be more readily apparent from the following detailed description, read in conjunction with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1   a  and  1   b  are perspective views of the locking adapter of the present invention 
       FIGS. 2   a ,  2   b ,  2   c , and  2   d  are, respectively; a perspective view, a top plan view, a side elevation view, and a bottom plan view of the actuator of the present invention 
       FIGS. 3   a ,  3   b , and  3   c  are, respectively, an end elevation view, a side elevation view in cross section, and an elevation view of the interior face of the adapter housing of the invention 
       FIGS. 4   a  and  4   b  are, respectively, a perspective view and a side elevation view of the housing end cap of the invention. 
       FIG. 5  is an exploded perspective view of a portion of the locking mechanism of the present invention. 
       FIGS. 6   a ,  6   b , and  6   c , are perspective views of the locking mechanism of the present invention 
       FIG. 7  is a perspective view of the locking mechanism and actuator assembled to the end cap; 
       FIG. 8  is a top plan cross-sectional view of the locking mechanism within the housing in its locked configuration; 
       FIG. 9  is a top plan cross-sectional view of the locking mechanism within the housing in its unlocked or release position; 
       FIG. 10  is a plan view of the one arrangement for fixing the adapter to a female cord termination; 
       FIG. 11  is a variant of the arrangement of  FIG. 10  which utilizes a novel collar arrangement; 
       FIG. 12  is a plan view of a strap as used in the arrangement of  FIGS. 10 and 11 ; 
       FIGS. 13(   a ) and  13 ( b ) are perspective views of the novel collar of  FIG. 11 ; 
       FIG. 14  is a perspective view of a split tapered sleeve for use with the collar of  FIGS. 11 and 13 ; 
       FIG. 15  is a perspective view of the arrangement of  FIG. 11  in its locking or fixing configurations; and 
       FIG. 16  is a perspective view of the adapter of the invention connected to a power cord and overmolded for fixing and protection. 
   

   DETAILED DESCRIPTION 
     FIGS. 1   a  and  1   b  are perspective views of the locking adapter  11  of the present invention, which comprises, in its assembled form a unitary, substantially hollow housing  12  having a closed end  13  and an open end  14  to which a cap  16  is affixed. Closed end  13  is configured as a female receptacle, having first and second male plug blade receiving openings  17  and  18 , an opening  19  for receiving a grounding pin, and a bolt hole  21  for receiving an assembly bolt, not shown, for attaching the cap  16  to the housing  12 , as will be discussed hereinafter. The cap end or open end  14  of the adapter has cap  16  affixed thereto, from which protrude male plug blades  22  and  23 , and a grounding pin  24 . It is to be understood that openings  17  and  18  and blades  22  and  23  may be polarized, wherein one blade (blade  23  in  FIG. 11   b ) is larger than the other being the “hot” blade. Also protruding from cap  16  is a grounding pin  24 . Thus end  14  with cap  16  is configured as a male plug. 
   Slidably mounted on a wall  26  of housing  12  is an actuator  27  which, as will be seen later, protrudes into the interior of housing  12 . Wall  26  has a slot  28  within which actuator  27  is carried and which allows actuator  27 , which has a striated or knurled surface  29  to be moved longitudinally back and forth between ends  13  and  14  of the housing. As will be more apparent hereinafter, when actuator  27  is at the limit of its travel toward end  13 , as shown in  FIGS. 1   a  and  1   b , as shown in  FIGS. 1   a  and  1   b , the adapter  11  is in the locked position. Conversely, when it is at the limit of its travel toward end  14  (and cap  16 ), the adapter  11  is in the unlocked position. 
     FIGS. 2   a ,  2   b ,  2   c , and  2   d  are respectively perspective view, a top plan view, a side elevation view, and a bottom plan view of the actuator  27 , which comprises a flat plate  31  joined to the top portion  32  by an alignment extension  33  which has a width slightly less than slot  28  to permit the actuator  27  to be moved longitudinally therein. Depending from the underside of plate  31  are first and second spaced actuating lugs  34  and  36  and a coiled spring receptacle  37  and a coiled spring receptacle  37  having a spring receiving hole  38  extending part way therethrough, as best seen in the dashed lines in  FIG. 2   d . It can be seen that hole  38  bottoms within receptacle  37 . A coil spring  40  is configured within hole  38 . 
     FIG. 3   a  is an elevation view of end  13  of housing  12 ,  FIG. 3   b  is a side elevation view in cross section along the line A—A of housing  12  and  FIG. 3   c  is an elevation view of that side of end  13  which faces the interior of housing  12 . As best seen in  FIGS. 3   b  and  3   c , a holed boss  41  protrudes from the interior face  42  for supporting a grounding pin (not shown) of a male plug, also not shown. An elongated tubular member  43  extends from the interior face for receiving an assembly bolt as noted in the discussion of  FIG. 1   a . First and second rectangular bosses  44  and  46  having rectangular apertures  47  and  48  therein protrude from face  42  for locating and holding blades  22  and  23  of  FIG. 1   b , as will be discussed more fully hereinafter. It is to be understood that the two bosses  44  and  46  can be replaced by a single boss having two apertures  47  and  48  therein. Extending from each side wall of housing  12  is a planar shelf  49 ,  51  which function to support movable elements of the locking mechanism. From the side walls of housing  12  protrude first and second slotted members  52  and  53 , having, respectively, slots  54  and  56  therein. Slotted member  53  is best seen in  FIGS. 1   a  and  1   b , and member  52 , not shown therein, is identical thereto. 
   End cap  16  is depicted in  FIG. 4   a , which is a perspective view thereof, and  FIG. 4   b , which is a side elevation view thereof, with certain other elements shown in dashed lines, but numerically designated. As can best be seen in  FIG. 4   a , the wall of the cap has a hole  57  therein for receiving and holding grounding pin  24  which is, preferably, a tight fit therein. Extending from the wall into the interior of housing  12  is an elongated boss  58  having a bore  59  therein for receiving the assembly bolt, not shown. 
   Below boss  58  is a spring holding member  61  which holds and aligns spring  40  may be, as shown, a bored boss, or a simple protruding pin. A unitary boss  62  has slotted openings  63  and  64  for holding and allowing passage of  22  and  23  therethrough. If desired, boss  62  may comprise two separate slotted bosses, although molding or forming end cap  16 , which is of insulating, stiff plastic, as is housing  12 , may be simply where boss  62  is a unitary member having two slots  63  and  64  therein. First and second planar locating members  66  and  67  extending from the wall and are strengthened by ribs  68  and  69 . As will be apparent hereinafter, these members  66  and  67  function to align and maintain such alignment of elements of the locking mechanism. Along the bottom edge of cap  16  is a stop member  71  which is dimensioned to fit within the end of slot  28 , as an be seen in  FIG. 1   b , which functions to limit the movement of actuator  27  toward the caps end  14  of housing  12 , and to retain the actuator  27  within its slot  28 . 
   A portion of the locking mechanism  72  is shown in  FIG. 5 . Mechanism  72  comprises a male plug blade receiving member  73  and a pivotable locking member  74 . As will be apparent hereinafter, there are two such locking assemblies as shown in  FIG. 5 . Blade receiving member  73  which is made of suitable metallic material has a flared proximal end  76  which is dimensioned to fit within opening  47  or  48  in housing  12 , which is dimensioned to allow end  76  to spread apart to receive a male blade and, through the natural spring action of member  73 , to grip it. The distal end  21  of member  73  passed through slot  63  or  64  in cap  16  and contributes one blade  23  of a male plug configuration, as shown in  FIGS. 1   a  and  1   b . Approximately midway of member  72  is an opening  77  which has an angular portion  78  and a straight portion  79 . Angular portion  78  has a slightly greater length than straight portion  79 . Pivotal locking member  74  has a barb  81  on one end thereof which is adapted to fit within an opening  82  in end  76  of member  73 . The end opposite barb  81  has a mounting lug  83  having a length slightly less than the length of the angular part  78  but greater than the length of straight opening  79 , made so by a small projection  84  thereon. Thus, in mounting locking member  74  to member  73 , the lug  83  is oriented to pass through angular opening  78  and then the member  74  is twisted to align lug  83  with the straight opening  79 , with projection  84  on the side of member  73  opposite member  74 . Mounted in this way, member  74  is pivotably mounted to move in a plane perpendicular to the surface plane of member  73 , as indicated by the arrows, without escaping or otherwise disconnecting with member  73 . At the rear of the top of member  74 , the edge thereof has a sloping ramp  86  which, as will be apparent hereinafter functions as a camming surface for lug  34  or  36  of actuator  27 . A stop member  87  projects upward from the top edge of member  74 . 
     FIGS. 6   a ,  6   b , and  6   c  are various perspective views of the assembled locking mechanism, with, in each view, the member  74  in its locking position where the barb  81  is within the opening  82  and, in the presence of a male blade, penetrates the hole therein to lock the blade within blade receiving member  73 . 
   The assembly of the cap  16 , the locking mechanisms  72  and the position of the actuator  27  in the locking position, where the spring  40  forces the lug  36  against stop member  87 , is shown in perspective in  FIG. 7 . 
     FIG. 8  is a top plan view in cross-section showing the action of the actuator to maintain or lock the blades  91  and  92  of a male plug within adapter  11 . The spring  40  applies a force to actuator  27  to cause the lugs  34  and  36  to press against stop member  87 , thereby preventing member  74  from pivoting and thus maintaining barbs  81  in the holes in blades  91  and  92 , locking them in place. 
   In  FIG. 9  the actuator  27  has been moved (to the right in the figure) and the lugs  34  ride up ramp  86 , thereby depressing that end of the locking member  74 , causing it to pivot and thereby raising barbs  81  to an unlocked position, enabling disconnect from the male plug (not shown). 
   The power supply cord conventionally is terminated in a female receptacle to which the adapter  11  of the present invention is connected by means of blades  22  and  23  and grounding member  24 . The other end  13  of the adapter  11  receives the male plug of the cord from the apparatus. As a consequence, it is desirable to affix the adapter to the power cord female connector. There is shown in  FIG. 10  an embodiment of the invention wherein the adapter  11  is strapped to a female termination  95  of the power cord. In the arrangement of  FIG. 10  first and second strap  93  and  94  preferably of flexible plastic and having striated surfaces, are affixed slotted members  52  and  53  and extend behind the female member  95  to a split collar  96  having therewithin a split sleeve  97  surrounding the power cable  98 . The straps  93  and  94  pass between the opening in collar  96 , shown in dashed lines, and sleeve  97 . Sleeve  97  pushed up against the end of strain relief of female connector  95  and collar  96  is tightened by means of bolt  99 , thereby affixing the straps to the collar/sleeve assembly. Thus, adapter  11  is firmly held in place connected with female member  95  and cannot disconnect. It is to be understood that the split sleeve/collar arrangement is only one of several possible ways to affix the straps  93  and  94 . 
   In  FIG. 11  there is shown a variant of the arrangement of  FIG. 10  in which a novel strap clamping collar  101  in used in conjunction with tapered split sleeve  102 , which is best seen in  FIG. 14 . Clamping collar  101  has first and second portions  103  and  104  to form a complete collar surrounding sleeve  102 , as will be discussed hereinafter. 
     FIG. 12  is a plan view of the strap  93  to which strap  94  is identical. Such a strap, which is made of flexible plastic material, has an array of striations or grooves  106  and an enlarged end  107 . The strap has a width such that it can pass through the slot in slotted member  52  and  53 , but the width of the end  107  of the strap cannot pass through the slot in members  52  or  53 , and thus prevents the strap from being pulled out of member  52  or  53 . Such straps are commercially available and have, at the end opposite the enlarged end, and attached thereto, a locking member  108  or  109 , which are shown in  FIGS. 13   a  and  13   b , removed from the end of the strap. In the commercial configuration enlarged end  107  is not present, and the strap  93  has a distal end  11 . When the distal end  111  is inserted in the locking member  108  at its other end, it can be pulled therethrough, but it cannot be withdrawn. Thus the strap can be used to bind wires or other elongated materials together. In  FIGS. 13   a  and  13   b , each of the members  103  and  104  has a pocket  112  or  113  therein which is dimensional to receive and hold a locking member  108  or  109 . Each pocket  112 ,  113  has a slot  114 ,  116  to allow passage of strap  93  or  94  into and through the corresponding locking member  108 ,  109  contained in the pocket. For commercial consideration not shown, locking member and pocket can be molded and manufactured as one piece into halves of  103  and  104  of collar  101 . Members  103  and  104  are keyed together by a suitable key  117  and keyway  118  arrangement, as best seen in  FIG. 13   a . When keyed together, members  103  and  104  have a tapered bore  119 , which, as shown in  FIG. 11 , surrounds a tapered sleeve  102 , which has a split  121 , as shown in  FIG. 14 . Sleeve  102  is preferably made of rubber or a compressible plastic material which, as sleeve  102  is forced into tapered bore  119 , compresses to close split  121 . 
   In  FIG. 15  there is shown the manner in which adapter  11  is firmly attached to female member  95 . As straps  93  and  94  are pulled through member  101 , which is pushed forward until it and sleeve  102  bear tightly against the rear end of strain relief  122  of member  95 , the straps are locked by members  108  and  109 , and thus adapter  11  is firmly attached to female member  95  and cannot be removed except by cutting straps  93  and  94 . 
   In  FIG. 16  there is shown an embodiment of the invention wherein adapter  11  constitutes the female termination of the power cable  98 . In this embodiment, the standard female termination is removed and the bare wires are affixed to the male plug blades  22  and  23  and ground pin  24  as by soldering. The connection is then encapsulated within a plastic or, for example, rubber overmold  123 . 
   The basic adapter of the present invention is amenable to other configurations such as a gang configuration of several side by side adapters having a plurality of female receptacles with only one male plug, as represented by the male plug blades  22  and  23  and grounding member  24 . For example, the principles and features of the present invention may be readily adapted to continental, European, or other type plugs. 
   From the foregoing, it can be seen that the adapter is relatively quite simple, having only three moving parts, and can be easily assembled or disassembled. 
   It is to be understood that the various features of the present invention might be incorporated into other types of connector adapters, and that other modifications or adaptations might occur to workers in the art. All such variations and/or modifications are intended to be included herein as being within the scope of the present invention as set forth. Further, in the claims hereinafter, the corresponding structures, materials, acts, and equivalents of all means or step-plus-function elements are intended to include any structure, materials, or acts for performing the functions in combination with other elements as specifically claimed.