Abstract:
A plurality of prongs of a connector box and a plurality of receptacles of a receptor box are electrically connected by mating each respectable pairs together. The boxes are coupled by a mechanical leveraged maneuver. The connecting device then connects vehicular circuits of an electric vehicle including those for auxiliary equipment to a battery-carrying trailer which is to be mechanically attached thereto and allows the electric vehicle to either extend its range, or be rescued from power shortage by electricity supplied by other than batteries onboard therein. The connecting device has a safety mechanism for preventing accidental separation of an electric connection, and for protecting operators from receiving electrical shock.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a connecting device for electrically connecting an electric vehicle to a battery-carrying trailer and/or an off-board electric supply system. 
   2. Description of Related Art 
   The accumulator batteries used in electric vehicles have to be periodically recharged from an electricity power grid through appropriate connecting devices. Conductive type of devices similar to household plugs have been in use, but are relatively cumbersome to handle, that is, to align mating parts and then pull them apart against a fitting-friction connection. Additionally, there are risks of possible electrical shock to operators. An inductive type of connector device has been suggested for transferring electric energy by way of electro-magnetic waves which provides easier handling and safety, but only in exchange for higher costs. 
   Neither type of connector provides a specific safety mechanism against any accidental pulling apart of the mating connections, which is the kind of precaution needed in the case of supplying off-board electricity from a battery-carrying trailer to electric vehicles as described, for instance, in U.S. Pat. No. 5,559,420, where two vehicles are in motion together. The evaluation of electric vehicles and the ability to rescue a disabled electric vehicle subject to a power shortage, by mechanically attaching an auxiliary battery-carrying trailer, is becoming more necessary inasmuch as Ground Positioning System and telecommunication technology have been developed to show where help is needed as well as when help is available. 
   However, an electric vehicle should have a receiving port at its tail-end because the source of electricity supply is to be towed behind it. Many conventional electric vehicles have their recharge ports normally positioned at the front of the vehicle, and it would be generally impractical for an electric vehicle to have two separate ports. In addition, a battery-carrying trailer itself requires recharging by a commercial power grid. Thus, the prior art is still seeking an efficient and economical solution to these issues. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing problems of the prior art, an object of the present invention is to provide an external power source connecting device for an electric vehicle which can prevent any unintended separation of an electrical connection of the electric vehicle with battery-carrying trailers and/or off-board electric supply systems by providing an inexpensive and easy, yet safe to handle, safety mechanism thereon. 
   A further object of the present invention is to provide an external power source connecting device for electric vehicles which may be used for multiple purposes involved in operating electric vehicles and battery-carrying trailers. 
   In order to achieve the aforementioned objects, an external power source connecting device for an electric vehicle, of the present invention, comprises a receptor unit having a plurality of receptacles for either completing or breaking vehicular circuits at one time; a connector unit having a plurality of prongs to mate with the receptacles and having a safety mechanism against any accidental pull-apart force. The construction of the receptor unit and the connector unit is provided in such a manner to generate a force applying leverage for easy handling and to assure safety, and to accommodate related wiring from the receptor unit and the connector unit to the drive motors of an electric vehicle and its vehicular circuits, to the batteries onboard the vehicle, to batteries onboard a battery-carrying trailer and to a power grid, respectively. 
   While novel features of the invention are set forth in the preceding description, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings. 
       FIG. 1  is a perspective view illustrating an electric vehicle mechanically connected with a battery-carrying trailer applying an external power source connecting device of electric vehicle according to one embodiment of the present invention. 
       FIGS. 2A and 2B  illustrate perspective views of a receptor unit of the external power source connecting device on the electric vehicle according to an embodiment of the present invention.  FIG. 2A  shows the receptor unit with a lid closed and  FIG. 2B  shows the receptor with the lid opened. 
       FIGS. 3A and 3B  illustrate respectively a horizontal view and a cross-sectional view of the receptor unit according to the embodiment of the present invention with the lid closed respectively. 
       FIGS. 4A and 4B  illustrate a horizontal view and a cross-sectional view of a connector unit of the external power source connecting device of an electric vehicle according to any embodiment of the present invention respectively. 
       FIG. 5  illustrates a perspective view of electrical connection between the receptor unit and the connector unit for supplying electricity. 
       FIGS. 6A and 6B  illustrate a partially cutaway horizontal view and a partially cutaway cross-sectional view of the electrical connection between the receptor unit and the connector unit for electricity supplying according to the embodiment of the present invention respectively. 
       FIG. 7  illustrates a circuit diagram of the electric vehicle while the lid of the receptor unit is closed and the vehicle is operating without being electrically connected to the battery-carrying trailer according to an embodiment of the present invention. 
       FIG. 8  illustrates a circuit diagram of the electric vehicle and the battery-carrying trailer while the connector unit of the battery-carrying trailer and the receptor unit of the electric vehicle are electrically connected together according to the embodiment of the present invention. 
       FIG. 9  illustrates a circuit diagram of the electric vehicle while the electric vehicle is electrically connected to an off-board power supply system for recharging batteries onboard the electric vehicle according to an embodiment of the present invention. 
       FIG. 10  illustrates a circuit diagram of the battery-carrying trailer while the battery-carrying trailer is electrically connected to an off-board power supply system for recharging batteries onboard the battery-carrying trailer according to the embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the preferred embodiments of the invention which set forth the best modes contemplated to carry out the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be obvious to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention. 
   One preferred embodiment of an external power source connecting device for an electric vehicle according to the present invention will be hereinafter described with reference to  FIG. 1  to  FIG. 10 . 
     FIG. 1  illustrates an electric vehicle  1  and a battery-carrying trailer  2  which is mechanically attached to the vehicle  1  by way of a ball  3  and an eyed tie-rod  4 , an electrically connective unit  5  comprising a receptor unit  6  attached on the rear of the vehicle and a connector unit  7  attached to an end or tip of a cable  8  is used to supply off-board electricity from a power source to the vehicle, when the vehicle is incapable of being driven by its own power. 
   A power shortage is liable to occur for electric vehicles when a timely recharge has been forgotten, a planned itinerary is overridden, and chance incidents or vehicular failure is faced. The battery-carrying trailer  2 , providing an off-board source of electricity supply, may be used either for rescuing disabled vehicles on such occasions or simply for extending the driving range of the vehicle. 
   Referring to  FIGS. 2A and 2B  perspective views of the receptor unit  6  are shown, a lid  16  is in a closed position over a receptor box  9  in  FIG. 2A  whereas it is shown opened in  FIG. 2B . The lid  16  has a hinge  16   a . The receptor unit  6  is to be located at the rear end of the vehicle  1  through which all of the vehicular electrical power line circuits are channeled. The driving circuit is channeled by way of a receptacle box  13 , and auxiliary circuits such as for various functional lights are channeled by way of receptacle box  15 . A pair of electrically conductive prongs  17  completes or connects, when the lid is closed, the driving circuit from the onboard batteries to a controller and drive motors. 
     FIGS. 3A and 3B  show the receptor unit  6  and relative locations of receptacle boxes when the lid  16  is closed. The lid can be friction-held against the receptor casing  10  and stopped at an inner wall  19 . Alternately, a locking device (not shown) can be added to prevent tampering. The receptacle boxes  13  and  15  are held within a cutout defined on the receptor casing  10  and by the inner wall  19 . 
     FIGS. 4A and 4B  show the connector unit  7  in the general form of a nozzle gun in an unlocked mode in which a safety trigger  31  is free for movement by an operator. The entire connector unit  7  is shock-free as the first safety contact  25  is shown in an open position to break any electricity supply to the mating power prongs  27   a  and  27   b . The prong boxes  26  and  28  are positioned to match and align with the sockets or ports on receptacle boxes  13  and  15  on the receptor unit  6  as shown in  FIG. 3 . The safety trigger  31  is free to move so it may be generated to slide into a notch  40  cut on a control cam  35 , which is held immovable by a wedge member  43 , tensioned down by a spring  42 , which is dropped down into a notch  41  cut on the same cam. Otherwise, the control cam  35  is designed to rotate and be operator thumb-turned by the exterior knob  36 . All cords, omitted from illustrations for clarity, run through a handle grip  22 . Note, the prongs  27   a  and  27   b  are positioned within a recess  29  in the housing  20 . 
   A pilot lamp  45  is off in this mode. Other types of colored lamps, for instance, showing the current charge status of batteries, may be added. 
   As is shown in  FIG. 5 , the connector unit  7  can to be coupled with the receptor unit  6  which is on the electric vehicle  1 . First, the lid  16  is opened and the operator inserts the connector unit  7  into the receptor unit  6 , with the nozzle tip  23  against the protrusion  12  provided on the front wall of receptor box  9  as shown in  FIGS. 3A and 3B , as well as against the bias of the spring  24   a  provided within the housing or connector body  20  as shown in  FIGS. 4A and 4B , thereby making the first safety contact  25  close in an automatic manner. Then the connector unit  7 , held by hand, is pivoted in a downward motion against the front wall to provide a mechanical force advantage until it is stopped at the receptor threshold  18 . 
   Inserting the connector unit  7  into the receptor unit  6  is automatically guided by the slanted shaped tips  23  and  11  and requires no visual verification for this maneuver. The action involved is akin to the handling maneuver of a conventional gasoline-feeding nozzle that people are accustomed to. This action produces leverage at a fulcrum formed by the shaped tips  23  and  11  of the housing for the connector unit  7  and of the housing for the receptor unit  6  when they meet. This pivoting snap or yanking motion would require less force than the motion required for a linear thrusting of a conventional conductive set of prongs and sockets because of the mechanical advantage of the present invention. 
     FIGS. 6A and 6B  show an inner mechanism of the connector unit  7  after it has been coupled with the receptor unit  6  and the knob  36  has been thumb-turned clockwise, whereby electricity is free to run through the prong boxes  26 ,  28  and the mating receptacle boxes  13 ,  15 . 
   Coupling at a correct relative position, and thereby ensuring proper mating of the prongs with the receptacles, is assisted by the vertical guide wall  30  on the connector unit  7  and the vertical guide wall  19  on the receptor unit  6 . During a yank down process, the rounded-off trigger tip  33  rides over the receptor threshold  18 . Then the spring  34  pulls back the tip  33 , locking it with the ledge or flange on the threshold  18 . The wedge  43  is now forced out of the notch  41  as the spring tip  44  is pushed upward by the receptor threshold  18 , enabling the control cam  35  to be turned. The stop pin  38  defines the permissible turn angles. As the knob  36  is thumb-turned clockwise, the second safety switch contact  39  is closed by the control cam  35 , and electricity is now permitted to run through the entire unit as explained above, during which time any movement of the safety trigger  31  is restricted by the control cam  35 . As can be appreciated, the relative position of the receptacles and prongs could be switched between the connector unit  7  and the receptor unit  6 . 
   To discontinue an operation of supplying external electricity, the above procedure is reversed, first, the knob  36  is thumb-turned counter-clockwise back, the safety trigger  31  is squeezed to release the trigger tip  33  from the lock, the connector unit  7  is yanked upward by the operator, and it is ejected by the spring  24   a  out of coupling with the receptor unit  6 . Thus, the present invention incorporates first and second electrical safety switch units to protect the operator. 
     FIG. 7  shows the vehicular circuits when an electric vehicle is made operable in a normal manner, with no electricity supply from a battery-carrying trailer. The receptor unit  6  is located at the rear-end of the vehicle  1  and the lid  16  closed, thus completing the drive circuit  54  in which electricity from onboard batteries  51  is led respectively through the receptacle  14   a , the bridging prongs  17  on the closed lid, the receptacle  14   b , and the controller  53  to the drive motors  52 . The auxiliary circuit  58  is likewise completed through the bridged receptacles  15  in which an auxiliary battery  55  is used to power various vehicular lights  57  that are switched on or off by the control devices  56 . 
     FIG. 8  shows the vehicular circuits where a battery-carrying trailer  2  is mechanically attached to an electric vehicle and electrically connected by the connective unit  5  to accumulator batteries. The batteries  59  on the trailer now supply needed electricity to the drive motors  52 , in place of the batteries  51  on the vehicle. 
   The pair of prongs  27   a  and  27   b , located on the connector unit  7 , as shown in  FIG. 4 , mate with the receptacles  14   b  and  14   c  on the receptor unit  6 , and is differentiated in its relative location from that of the bridging pair  17  on the lid  16 . The pair  17  mates with the receptacles  14   a  and  14   b , as shown in  FIG. 7 . 
   The prongs  27   a  and  27   b  will not provide an electrical shock to an operator because the drive circuit  8  is double-shielded by the two safety contacts  25  and  39  against unintentional completion. A diode  46  directs current. Various inter-vehicular communications including lighting such as the taillights  2   a  shown in  FIG. 1  are subjected to the control devices  56 . 
     FIG. 9  shows the circuits formed for recharging an electric vehicle by the power grid. The connector unit  7  in this case is attached to an end of the cable from a charger  61  located at the recharging station  60 , and is modified as to the location of its prongs. The recharging prongs  27   a  and  27   b  now mate with the receptacles  14   a  and  14   b , and electricity supply is directed to the batteries  51  on the vehicle  1 . 
     FIG. 10  shows the circuits formed for recharging a battery-carrying trailer by the grid. The receptor unit  6  in this case is attached to the charger  61  which is located at the recharging station  60 , and is modified to include a protrusion (not illustrated) to actuate the switch  46   c  which, provided within the connector body  20  shown for instance in  FIGS. 4A and 4B , directs current to the batteries  59  on the trailer  2 . 
   Although the present invention has been fully described in connection with the preferred embodiment thereof, it is to be noted that various changes and modifications apparent to those skilled in the art are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. 
   Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the amended claims, the invention may be practiced other than as specifically described herein.