Abstract:
A swiveling electrical connector is described. A male assembly has three conductors electrically isolated from each other. A first one of the three conductors in the male assembly includes a cylindrical surface. A female assembly has three conductors electrically isolated from each other and a receptacle for receiving the male assembly. A first one of the three conductors in the female assembly has a clip assembly extending therefrom for contacting the cylindrical surface of the first conductor in the male assembly. A locking mechanism is coupled to the female assembly for locking the male and female assemblies together when the male assembly is inserted into the female assembly thereby providing electrical contact between the male assembly conductors and the female assembly conductors. The male and female assemblies rotate relative to each other when locked together, the clip assembly in the female assembly maintaining contact with the first conductor in the male assembly while the male and female assemblies rotate relative to each other.

Description:
RELATED APPLICATION DATA 
     The present application is a Continuation-in-Part of U.S. application Ser. No. 08/637,001 filed on Apr. 18, 1996, which issued on Sep. 8, 1998, as U.S. Pat. No. 5,803,750; which is a division of U.S. application Ser. No. 09/064,016 filed on Apr. 20, 1998, the entirety of which is incorporated herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The present application relates to a swiveling electrical connector. More specifically, the present application describes an electrical connector having two assemblies which freely rotate relative to each other and which may be quickly connected and disconnected. 
     The use of electrical power tools on building construction sites necessitates the reliable distribution of high-current electrical power throughout the often chaotic and obstacle-laden environment which such sites represent. Typically, power is distributed on such sites through the use of conventional electrical extension cords which are terminated with fixed, three-prong plugs and receptacles. As is well known to construction workers, such fixed connectors present a variety of practical problems. For example, the nature of construction work is such that the worker often must move over a considerable area and maneuver himself in close quarters while using the same power tool. Under such conditions, fixed connectors tend to twist and knot creating hazardous conditions as well as causing considerable wear and tear on the respective power cords. Moreover, as fixed connectors are dragged through the construction site, they tend to snag on comers and other obstacles resulting in disconnection due to the tension on the power cord which, in turn, results in a reduction in the efficiency of the worker as he scrambles to reconnect the line or free up a snag. To prevent such disconnections, workers typically knot the cords together near the connection. However, this merely tends to exacerbate the problems related to cord wear and snagging. 
     Other problems relate to the fact that construction workers typically use a variety of different power tools in a single work area. In general, power tools have power cords built into their handles which are several feet long and which are terminated with fixed three-prong plugs. When switching power tools, the worker must reach the connection, disconnect the current power tool, connect the new power tool, and store the disconnected power tool. If the worker is in a precarious position such an operation is difficult at best. That is, the connection may be several feet away and out of reach unless the worker extricates himself from his working position. In addition, the built in cords of the power tools present handling and storage problems which are often difficult to deal with under practical conditions. 
     Attempts have been made to address some of the problems discussed above with swiveling electrical connectors. However, none of these connectors provides features which address all of these problems. For example, U.S. Pat. No. 1,174,379, No. 2,176,137, No. 2,181,145, No. 2,465,022, No. 2,474,070, No. 3,387,250, and No. 4,894,014 all describe various electrical connectors each of which has two assemblies which rotate relative to each other. However, none of these designs is appropriate for use in the construction environment in that they provide for connection between electrical cords having only two conductors. Because of the additional complexity represented by a third conductor, none of the designs described in these patent could be readily converted to provide a rotatable connection for three conductors. Moreover, all of these connectors maintain permanent connections between the two assemblies. While this may prevent disconnection problems, it fails to address the problems discussed above with regard to the interchangeability of power tools. 
     The rotatable connector described by U.S. Pat. No. 3,321,729 has two permanently connected assemblies  12  and  50  which rotate relative to each other. While this design allows connection and disconnection from separate power cords via prongs  38 ,  40  and receptacles  64 ,  66 , it does not address the problem of cord disconnection due to tension. In addition, the power cords connected by this device have only two conductors. 
     U.S. Pat. No. 3,629,784 describes a three-conductor swivel connection which is permanently fixed in the handle of a power tool. While this design may alleviate some of the problems related to the twisting and knotting of power tool power cords, it does not address the problems associated with the need to quickly and efficiently switch between power tools. Moreover, because a connection must still be made between the other end of the tool&#39;s power cord and an extension cord (presumably using the conventional three-prong plug and receptacle), all of the hazards associated with such a connection are still present. 
     From the foregoing, it is apparent that there is a need for a swiveling electrical connector which provides a connection between power cords having three conductors, maintains the connection even under considerable tension, and is quickly and easily connected and disconnected. 
     SUMMARY OF THE INVENTION 
     The present invention provides a swiveling electrical connector which addresses each of the problems discussed above. Specifically, the present invention provides a connector for triple-conductor power cords comprising male and female coupling assemblies which rotate relative to each other when connected. The connector of the present invention is a plunger-type connector in which an elongated male assembly is inserted into an open female assembly. Each of the assemblies has three concentrically arranged conductors separated by concentrically arranged insulating layers. Each conductor is in electrical contact with its corresponding conductor in the other assembly when the assemblies are connected. 
     The connection between the assemblies is secured by a locking mechanism similar to the type employed for pneumatic hose connections. That is, a spring-loaded, slidable collar on the female assembly is employed in a first position to secure a ring of ball bearings in an annular groove around a portion of the male assembly, thereby locking the assemblies together; and in a second position to allow the ball bearings to retract from the groove, thereby allowing the assemblies to be disconnected. This “quick-release” locking mechanism allows the assemblies to be readily connected and disconnected. 
     According to specific embodiments of the invention, each of the male and female assemblies are at least partially enclosed in a non-conductive sleeve which, when the assemblies are connected, combine with the collar mechanism to form a sleek, streamlined profile resistive to snagging on edges and corners by which the power cord and connector may be dragged. According to more specific embodiments, the non-conductive sleeves are threaded on their inner surfaces and engage corresponding threads on the exteriors of the male and female assemblies. In this way, the sleeves may be retracted from the assemblies if desired. 
     According to other specific embodiments, a male assembly designed according to the invention is the terminus of a short power cord which is permanently affixed to a power tool handle. The male assembly is for connection to an extension cord having a corresponding female assembly. Such embodiments are particularly useful in environments where power tools are frequently interchanged. Not only does the present invention facilitate easy connection and disconnection, the power tools are more easily stored without a cumbersome power cord. In a mass production environment, a single power cord terminated with a female assembly is provided for each work station on a retracting roller system. A number of power tools having the male assembly termination is also provided at each of the work stations. In a home environment, the fastidious do-it-yourself enthusiast can add one more level of organization to his workshop. 
     According to still other embodiments, one or both of the male and female assemblies are terminated with a conventional three-prong plug or receptacle to provide a variety of connection options for conventional extension cords, plugs and sockets. 
     The various embodiments of the invention provide several obvious advantages over conventional extension cords and connectors, as well as previous swiveling connector designs. For example, as discussed above, the swiveling nature of the connection reduces power cord wear and knotting. Also as discussed above, the connection assemblies of the invention are readily interchanged providing a high degree of flexibility and efficiency in a variety of work environments. The sleek profile prevents undesirable snagging, cord tension and resulting disconnection. The locking mechanism provides an additional safeguard against inadvertent disconnection while also providing a mechanical connection capable of supporting a considerable amount of weight. The value of this feature is obvious to anyone who has dropped a tool while roofing, or lost his balance on a scaffolding. 
     In addition to these advantages, embodiments of the present invention may be adapted to carry a wide range of amperage for both home and industrial use. Moreover, the manner in which the conductors are enclosed prevents shorting from external sources such as, for example, children and foreign objects. Likewise, the insulation between the conductors in the connection assemblies, and the configuration of the assemblies themselves are designed to prevent internal arcing. 
     Thus, according to the present invention an electrical connector is provided. A male assembly has three conductors electrically isolated from each other. A first one of the three conductors in the male assembly includes a cylindrical surface. A female assembly has three conductors electrically isolated from each other and a receptacle for receiving the male assembly. A first one of the three conductors in the female assembly has a clip assembly extending therefrom for contacting the cylindrical surface of the first conductor in the male assembly. A locking mechanism is coupled to the female assembly for locking the male and female assemblies together when the male assembly is inserted into the female assembly thereby providing electrical contact between the male assembly conductors and the female assembly conductors. The male and female assemblies rotate relative to each other when locked together, the clip assembly in the female assembly maintaining contact with the first conductor in the male assembly while the male and female assemblies rotate relative to each other. 
     A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a cut-away side view of a male assembly designed according to a specific embodiment of the invention; 
     FIG. 1B is a cut-away side view of a female assembly designed according to a specific embodiment of the invention; 
     FIG. 1C is a cut-away side view of the male and female assemblies of FIGS. 1A and 1B connected together; 
     FIG. 2 is a cut-away side view of the connector of FIG. 1C enclosed in a nonconductive sleeve; 
     FIG. 3A is a perspective view of the male assembly of FIG. 1A having a three-prong plug termination; 
     FIG. 3B is a perspective view of the male assembly of FIG. 1A having a three-prong receptacle termination; 
     FIG. 3C is a perspective view of the female assembly of FIG. 1B having a three-prong plug termination; 
     FIG. 3D is a perspective view of the female assembly of FIG. 1B having a three-prong receptacle termination; 
     FIG. 4 illustrates the use of a specific embodiment of the invention in a manufacturing environment; 
     FIG. 5A is a partial section view of a male assembly designed according to a specific embodiment of the invention; 
     FIG. 5B is a partial section view of a female assembly designed according to a specific embodiment of the invention; 
     FIG. 5C is a partial section view of the male and female assemblies of FIGS.  1 A and  1 B connected together; 
     FIGS. 5D and 5E are exploded views of male and female assemblies, respectively; and 
     FIG. 6 is a cut-away partial side view of the connector of FIG. 1C enclosed in a nonconductive sleeve. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following is a description of a specific embodiment of the present invention. 
     First, each of the features of the female and male assemblies is identified. Then the interaction of the assemblies is discussed. Features which are shown in more than one drawing retain the same reference designation throughout the drawings. 
     FIG. 1A is a cut-away side view of a male assembly  100  designed according to a specific embodiment of the invention. Male assembly  100  has three cylindrical, concentrically arranged conductors separated by insulation material  102 . Ground conductor  104 , the outermost of the conductors, connects with the ground wire of the power cord to which male assembly  100  is connected (not shown). Ground conductor  104  is characterized by an annular depression  106  around its exterior. The middle cylindrical conductor is a neutral conductor  108  which connects to the power cord&#39;s neutral line. Line conductor  110  connects with the line conductor of the power cord, conducting the line current to and from the female assembly shown in FIG.  1 B. Line conductor  110  is characterized at one end by a cone-shaped divet or receptacle  112 . 
     FIG. 1B is a cut-away side view of a female assembly  120  for connection to male assembly  100  of FIG.  1 A. Female assembly  120  also has three cylindrical, concentrically arranged conductors which are separated by insulation material  122 . Ground conductor  124 , the outermost of the conductors, connects with the ground wire of the power cord to which female assembly  120  is connected (not shown). Neutral conductor  126 , the middle conductor, connects to the power cord&#39;s neutral line and to neutral conductor  108  of male assembly  100  via neutral ball bearings  128  and neutral clips  130 . Cylindrical line conductor  132  connects with the line conductor of the power cord, conducting the line current to and from shaft line conductor  134  via line clips  136  and line ball bearings  138 . Connections from the various conductors of the male and female assemblies to their respective power cords may be achieved in a variety of ways and are well within the capabilities of one skilled in the art. 
     Shaft line conductor  134  is characterized at one end by a cone shaped surface  140  and is operable to move along the x-axis. As will be discussed, surface  140  is inserted into receptacle  112  when the male and female assemblies are connected. It will be understood that surface  140  and receptacle  112  may have a variety of contours and remain within the scope of the invention. For example, according to one embodiment, surface  140  has a spherical shape and receptacle  112  is in the shape of a rounded cup which matches the contours of surface  140 . In addition, shaft line conductor  134  is enclosed by a spring  142  which causes shaft line conductor  134  to resist force in the negative x-direction, and is secured within female assembly  120  against the force of spring  142  by the action of ball bearings  144  against a raised surface in insulation  122 . 
     A collar  148  encloses a portion of female assembly  120  and is also operable to move along the x-axis. The movement of collar  148  is limited in one direction by ball bearings  150  and in the other by a lip in ground conductor  124 . A spring  154  resists movement of collar  148  in the negative x-direction. When collar  148  is disposed as shown in FIG. 1B, it acts on ground ball bearings  156  causing them to extend into receptacle  158 . When collar  148  is moved in the negative x-direction, this inward pressure on ball bearings  156  from collar  148  is relieved due to the narrower aspect of collar  148  at its outer edge. Thus, ground ball bearings  156  may retract from receptacle  158  when collar  148  is moved in this manner. 
     FIG. 1C is a cut-away side view of male assembly  100  inserted into receptacle  158  of female assembly  120  thereby forming swiveling connector  160 . The reference numerals in the following discussion have been omitted in FIG. 1C for clarity, but are the same as the corresponding features in FIGS. 1A and 1B. Upon insertion of male assembly into receptacle  158 , surface  140  of shaft line conductor  134  is received into and contacts with similarly shaped receptacle  112  of male line conductor  110 . Force is exerted against shaft line conductor  134  in the negative x-direction compacting spring  142  which causes shaft line conductor  134  to exert an equal and opposite force against male line conductor  110 , thereby maintaining a secure electrical connection between the two. Contact between shaft line conductor  134  and line ball bearings  138  is achieved because the wider aspect of shaft line conductor  134  is disposed adjacent line ball bearings  138  in this position. Thus, the line conduction path is maintained through male line conductor  110 , shaft line conductor  134 , line ball bearings  138 , line clips  136 , and cylindrical line conductor  132 . 
     The connection between male and female assemblies  100  and  120  is securely maintained against the force of spring  142  by the interaction of collar  148  and ground ball bearings  156  of female assembly  120  with annular depression  106  of male assembly  100 . When male assembly  100  is inserted into receptacle  158  as shown in FIG. 1C, ground ball bearings  156  are forced into annular depression  106  by the action of the thicker portion of collar  148  on ball bearings  156 . In this way, a ground conduction path is maintained through male ground conductor  104 , ground ball bearings  156  and female ground conductor  124 . Moreover, with ball bearings  156  firmly pressed into annular depression  106 , male and female assemblies are locked together securely enough to support a considerable amount of weight, thus contributing to work place safety (e.g., falling power tools, momentary support for an off-balance worker, etc.). 
     The neutral conduction path is maintained through male neutral conductor  108 , neutral ball bearings  128 , neutral clips  130 , and female neutral conductor  126 . 
     To disconnect the assemblies, collar  148  is moved in the negative x-direction thereby positioning the thinner portion of collar  148  adjacent ground ball bearings  156 . Male assembly  100  may then be pulled out of female assembly  120  in the positive x-direction with little resistance as ball bearings  156  are able retract out of receptacle  158  and annular depression  106 . 
     FIG. 2 is a cut-away side view of the connector of FIG. 1C partially enclosed in a nonconductive material which gives the assembly a streamlined profile. This configuration reduces the likelihood of the connector snagging on objects when being dragged around a construction site. The profile is formed by collar  148  in conjunction with non-conductive sleeves  200  and  202  which together form a substantially continuous surface as shown in the figure. Moreover, non-conductive sleeves  200  and  202  have threads  204  on their inner surfaces which engage corresponding threads  206  on the exteriors of male and female assemblies  100  and  120 . Sleeves  200  and  202  are thus retractable from assemblies  100  and  120  to allow access to the connector for disconnection or maintenance purposes. 
     FIGS. 3A-3D are perspective views of male and female assemblies  100  and  120  terminated with either a three-prong plug or a three-prong receptacle. Receptacles  300  and  302  (FIGS. 3A and 3C) and prongs  304  and  306  (FIGS. 3B and 3D) allow the present invention to be used with conventional extension cords and connectors, thereby easily and inexpensively modifying any tool or environment to enjoy the benefits and advantages described above. The internal connections between the prongs/receptacles of FIGS. 3A-3D and the respective conductors of the corresponding male and female assemblies are not shown as the implementation of such connections may be done in a variety of ways which are well within the capabilities of one of ordinary skill in the art. 
     FIG. 4 illustrates the use of a specific embodiment of the invention in a manufacturing environment. Electricity is delivered to a work station  400  via line  402  on a retracting roller system  404 . Line  402  is terminated in a female connector assembly  406  designed according to the present invention (e.g., female assembly  120  of FIG.  1 B). Work station  400  is equipped with a number of power tools ( 408 - 414 ) each of which has a power cord “tail”  416  terminated in a male connector assembly  418  designed according to the invention (e.g., male assembly  100  of FIG.  1 A). The worker may easily switch between the power tools because of the “quick-release” nature of the connection between the male and female assemblies of the present invention. The advantages of such an arrangement are obvious to anyone who has worked in a similar environment. In addition to the efficiencies of time and space realized by such an arrangement, all of the benefits of a freely swiveling electrical connection discussed above are also enjoyed. 
     Another specific embodiment of the invention will now be described with reference to FIGS. 5A-5E and  6 . FIG. 5A is a partial section view of a male assembly  500  designed according to a specific embodiment of the invention. FIG. 5B is a partial section view of a female assembly  520  designed according to a specific embodiment of the invention. FIG. 5C is a partial section view of the male and female assemblies of FIGS. 5A and 5B connected together. FIG. 5D is an exploded view of male assembly  500 . Male assembly  500  has two conducting bands and one conducting cylinder separated by insulation material  502 . Ground conductor  504 , the outermost of the conductors, connects with the ground wire of the power cord to which male assembly  500  is connected (not shown). The inner band conductor  508  is a neutral conductor which connects to the power cord&#39;s neutral line. Line cylinder conductor  510  connects with the line conductor of the power cord, conducting the line current to and from the female assembly shown in FIG.  5 B. 
     FIG. 5E is an exploded view of a female assembly  520  for connection to male assembly  500  of FIG.  5 A. Female assembly  520  has three clip conductors assemblies which are separated by insulation material  522 . Ground conductor  524 , the outermost of the conductors, connects with the ground wire of the power cord to which female assembly  520  is connected (not shown), and with ground conductor  504  of male assembly  500  via a clip (not shown) similar to clips  525  and  536 . Neutral conductor  526 , the middle conductor, connects to the power cord&#39;s neutral line and to neutral conductor  508  of male assembly  500  via neutral clip  525 . Line conductor  532  connects with the line conductor  510  of the power cord, conducting the line current via line clip  536 . Connections from the various conductors of the male and female assemblies to their respective power cord wiring may be achieved using conducting plates  610  and screws  609 . Female assembly  520  is held together by a screw (not shown) which is inserted into hole  611 . 
     A collar  548  encloses a portion of female assembly  520  and is operable to move along the x-axis. The movement of collar  548  is limited in one direction by lip  550  and in the other by insulating material  608 . A spring  554  resists movement of collar  548  in the negative x-direction. When collar  548  is disposed as shown in FIG. 5B, it acts on ball bearings  556  causing them to extend into receptacle  558  via holes  559 . When collar  548  is moved in the negative x-direction, this inward pressure on ball bearings  556  from collar  548  is relieved due to the narrower aspect of collar  548  at its outer edge. Thus, ball bearings  556  retract from receptacle  558  back into holes  559  when collar  548  is moved in this manner. 
     FIG. 5C is a cut-away side view of male assembly  500  inserted into receptacle  558  of female assembly  520  thereby forming swiveling connector  560 . The reference numerals in the following discussion have been omitted in FIG. 1C for clarity, but are the same as the corresponding features in FIGS. 5A,  5 B,  5 D, and  5 E. Upon insertion of male assembly  500  into receptacle  558 , the line conduction path is maintained through male line cylinder conductor  510 , line clip  536 , and line conductor  532 . 
     The connection between male and female assemblies  500  and  520  is securely maintained against the force of spring  554  by the interaction of collar  548  and ball bearings  556  of female assembly  520  with annular depression  506  of male assembly  500 . When male assembly  500  is inserted into receptacle  558  as shown in FIG. 5C, ball bearings  556  are forced into annular depression  506  through holes  559  by the action of the thicker portion of collar  548  on ball bearings  556 . With ball bearings  556  firmly pressed into annular depression  506 , male and female assemblies are locked together securely enough to support a considerable amount of weight, thus contributing to work place safety (e.g., falling power tools, momentary support for an off-balance worker, etc.). 
     The neutral conduction path is maintained through male neutral conductor  508 , neutral clip  525 , and female neutral conductor  526 . 
     To disconnect the assemblies, collar  548  is moved in the negative x-direction thereby positioning the thinner portion of collar  548  adjacent ball bearings  556 . Male assembly  500  may then be pulled out of female assembly  520  in the positive x-direction with little resistance as ball bearings  556  are able retract out of receptacle  558  and annular depression  506 . 
     It will be understood that the embodiments of FIGS. 3A-3D and  4  may be implemented with the embodiment of FIGS. 5A-5E. 
     FIG. 6 is a cut-away side view of the connector of FIG. 5C partially enclosed in a nonconductive material which gives the assembly a streamlined profile. This configuration reduces the likelihood of the connector snagging on objects when being dragged around a construction site. The profile is formed by collar  548  in conjunction with non-conductive sleeves  600  and  602  which together form a substantially continuous surface as shown in the figure. Moreover, non-conductive sleeves  600  and  602  have threads  604  on their inner surfaces which engage corresponding threads  606  on the exteriors of male and female assemblies  500  and  520 . Sleeves  600  and  602  are thus retractable from assemblies  500  and  520  to allow access to the connector for disconnection or maintenance purposes. 
     While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in the form and details may be made therein without departing from the spirit or scope of the invention.