Abstract:
A power circuit includes a first electrically-energizable contactor configured to receive a first power input of 110-120 volts of alternating current (VAC), and a second electrically-energizable contactor configured to receive a second power input of 220-240 VAC. The first and second contactors are arranged such that when one of the first and second contactors is energized by the corresponding power input, the energized one of the first and second contactors prevents the other one of the first and second contactors from being energized.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of provisional patent application No. 60/458,460, filed on Mar. 28, 2003, the contents of which are incorporated herein by reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention is directed to a shore power interface. More particularly, the present invention is directed to a shore power interface for various sources of shore power.  
         BACKGROUND  
         [0003]    Some vehicles, for example, recreational vehicles, boats, and the like, may be equipped with a mechanism for connecting to shore power from a commercial power system. These vehicles may therefore be arranged such that electrical loads may be powered from shore power or from a battery on the vehicle.  
           [0004]    For example, U.S. Pat. No. 6,034,445 to Hewitt discloses a power source transfer lockout circuit. The transfer lockout circuit includes a monitoring circuit connected to each power source, which may require complicated logic and, therefore, increase manufacturing costs. Further, some shore power sources provide 110-120 volts of alternating current (VAC), while others provide 220-240 VAC. The aforementioned transfer lockout circuit does not provide a mechanism for distinguishing the type of shore power input.  
           [0005]    The shore power interface of the present invention solves one or more of the problems set forth above.  
         SUMMARY OF THE INVENTION  
         [0006]    In one aspect, the present invention is directed to power circuit, including a first electrically-energizable contactor configured to receive a first power input of 110-120 VAC, and a second electrically-energizable contactor configured to receive a second power input of 220-240 VAC. The first and second contactors are arranged such that when one of the first and second contactors is energized by the corresponding power input, the energized one of the first and second contactors prevents the other one of the first and second contactors from being energized.  
           [0007]    In another aspect, the present invention is directed to a method of operating a power circuit, including selectively supplying a power input to one of a first power input configured to receive 110-120 VAC and a second power input configured to receive 220-240 VAC, and energizing a contactor forming a current flow circuit with the selected one of the first and second power inputs. The energized contactor prevents another contactor associated with the other one of the first and second power inputs from being energized. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a schematic representation of a shore power interface in accordance with an exemplary embodiment of the present invention; and  
         [0009]    [0009]FIG. 2 is a diagrammatic side view of an exemplary vehicle including the shore power interface of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0010]    An exemplary embodiment of a shore power interface  100  is illustrated in FIG. 1. The shore power interface  100  may include a first power receptacle  102  and a second power receptacle  104  electrically connected to a power circuit  110 . The first power receptacle  102  may receive a utility power input from a first shore power source  106  providing 110-120 VAC. The second power receptacle  104  may receive a utility power input from a second shore power source  108  providing 220-240 VAC. The first power receptacle  102  may be structured, for example, as a standard three-prong receptacle, and the second power receptacle  104  may be structured, for example, as a three-prong twist-lock receptacle.  
         [0011]    The power circuit  110  may include a first AC contactor  112 , a second AC contactor  114 , a power transformer  116 , and a signal transformer  118 . The first AC contactor  112  may include a coil  120 , a first contact  122 , a second contact  124 , and a third contact  126 . The first AC contactor  112  may further include one or more additional contacts  128  for other desired uses. The contacts  122 ,  124 ,  126 ,  128  may be connected to each other via a non-electrically conductive rod  130 , for example, a plastic rod, movable relative to the coil  120 . The rod  130  may include a magnetic end portion  132  proximate the coil  120 . When energized, the coil  120  generates a magnetic field that attracts the end portion  132 , thus moving the rod  130  and the contacts  122 ,  124 ,  126 ,  128  toward the coil  120 .  
         [0012]    The first AC contactor  112  may also include first, second, and third inputs  134 ,  136 ,  138 , respectively, and corresponding first, second, and third outputs  144 ,  146 ,  148 , respectively. The corresponding inputs  134 ,  136 ,  138  and outputs  144 ,  146 ,  148  are connectable to each other via the first, second, and third contacts  122 ,  124 ,  126 , respectively. As shown in FIG. 1, when the third input  138  and the third output  148  are connected by the normally-closed third contact  126 , the first and second inputs  134 ,  136  are not connected to the first and second outputs  144 ,  146  by the normally-opened first and second contacts  122 ,  124 .  
         [0013]    Similarly, the second AC contactor  114  may include a coil  150 , a first contact  152 , a second contact  154 , and a third contact  156 . The second AC contactor  114  may further include one or more additional contacts  158  for other desired uses. The contacts  152 ,  154 ,  156 ,  158  may be connected to each other via a non-electrically conductive rod  160 , for example, a plastic rod, movable relative to the coil  150 . The rod  160  may include an metallic end portion  162  proximate the coil  150 . When energized, the coil  150  generates a magnetic field that attracts the end portion  162 , thus moving the rod  160  and the contacts  152 ,  154 ,  156 ,  158  toward the coil  150 .  
         [0014]    The second AC contactor  114  may also include first, second, and third inputs  164 ,  166 ,  168 , respectively, and corresponding first, second, and third outputs  174 ,  176 ,  178 , respectively. The corresponding inputs  164 ,  166 ,  168  and outputs  174 ,  176 ,  178  are connectable to each other via the first, second, and third contacts  152 ,  154 ,  156 , respectively. As shown in FIG. 1, when the third input  168  and the third output  178  are connected by the normally-closed third contact  156 , the first and second inputs  164 ,  166  are not connected to the first and second outputs  174 ,  176  by the normally-opened first and second contacts  152 ,  154 .  
         [0015]    The power circuit  110  may include a hot wire  300  from the first power receptacle  102  connected to the coil  120  of the first AC contactor  112  via a wire  302 . The hot wire  300  may also be connected to the first input  134  of the first AC contactor  112  via a wire  304 . The coil  120  of the first AC contactor  112  may be connected to the third input  168  of the second AC contactor  114  via a wire  306 , and a wire  308  may connect the third output  178  of the second AC contactor  114  to a neutral wire  310  of the first power receptacle  102 . Another wire  312  may connect the wire  308  with the second input  136  of the first AC contactor  112 .  
         [0016]    The hot wire  300  of the first power receptacle  102  may be connected to the signal transformer  118  via a wire  314 , and another wire  316  may connect the signal transformer  118  to the neutral wire  310  of the first power receptacle  102 . The hot wire  300  may include a circuit breaker  318  arranged to prevent damage to the power circuit  110 .  
         [0017]    The power circuit  110  may also include a first hot wire  400  from the second power receptacle  104  connected to the coil  150  of the second AC contactor  114  via a wire  402 . The first hot wire  400  may also be connected to the second input  166  of the second AC contactor  114  via a wire  404 . The coil  150  of the second AC contactor  114  may be connected to the third input  138  of the first AC contactor  112  via a wire  406 , and a wire  408  may connect the third output  148  of the second AC contactor  114  to a second hot wire  410  of the second power receptacle  104 . Another wire  412  may connect the second hot wire to the first input  164  of the second AC contactor  114 . Each of the first and second hot wires  400 ,  410  may include a circuit breaker  418  arranged to prevent damage to the power circuit  110 .  
         [0018]    The first output  144  of the first AC contactor  112  may be connected to a first end  190  the power transformer  116  via wires  500 ,  502 , and the second output  146  of the first AC contactor  112  may be connected to a center tap  192  of the power transformer  116  via a wire  504 . The first output  174  of the second AC contactor  114  may be connected to the first end  190  of the power transformer  116  via wires  506 ,  502 , and the second output  176  of the second AC contactor  114  may be connected to a second end  194  of the power transformer  116  via a wire  508 .  
         [0019]    The power circuit  110  may include a single phase diode bridge  520  arranged to receive a voltage from the power transformer  116  and to rectify the alternating current to direct current (DC). The diode bridge  520  may feed the voltage to an LC filter  522 , which in turn may feed current to an opto-coupler  524 . The opto-coupler  524  may be electrically connected to an electronic control module (ECM)  530 . The signal transformer  118  may also be connected to the ECM  530  The power circuit  110  may also include a first ground wire  320  associated with the first power receptacle  102  and a second ground wire  420  associated with the second power receptacle  104 . The second power receptacle  104  may also include a neutral lead  422 .  
         [0020]    As shown in FIG. 2, the shore power interface  100  may be associated with a vehicle  200 , for example a truck, a boat, a recreational vehicle, an automobile, or the like, having a frame  202 . The ECM  530  may control power distribution to at least one load  210  associated with the vehicle  200 . The at least one load may include an air conditioning unit, a heater, a refrigerator, or the like. The power circuit  110  may also include a first ground wire  320  associated with the first power receptacle  102  and a second ground wire  420  associated with the second power receptacle  104 . Referring to FIG. 1, the first and second ground wires  320 ,  420  may be connected to the frame  202  of the vehicle  200 . The second power receptacle  104  may also include a neutral lead  422 .  
       INDUSTRIAL APPLICABILITY  
       [0021]    When the vehicle  200  is stationary, the shore power interface  100  may be connected to a source of shore power  106 ,  108 , where available, to provide utility power to the at least one vehicle load  210  without having to operate the vehicle&#39;s engine (not shown).  
         [0022]    For example, the shore power interface  100  may be connected to the first shore power source  106  providing 110-120 VAC via the first power receptacle  102 . As long as the second power receptacle  104  is not connected to the second shore power source  108 , as explained below, a current is fed to the coil  120  of the first AC contactor  112  via hot wire  300  and wire  304 . The current energizes the coil  120 , causing the rod  130  and associated contacts  122 ,  124 ,  126 ,  128  to move from a first position to a second position in a direction toward the coil  120 . In the second position, the normally-closed third contact  126  is opened and the normally-opened first and second contacts  122 ,  124  are closed. A circuit is then formed that provides a flow of current from the first power receptacle  102  to a first end  190  of the power transformer  116  via hot wire  300 , wire  302 , first input  134 , first contact  122 , first output  144 , and wires  500 ,  502 , and from the center tap  192  of the power transformer  116  to the first power receptacle  102  via wire  504 , second output  146 , second contact  124 , second input  136 , wire  312 , and neutral wire  310 . With a transformer ratio of 2:1 for voltage between the first end  190  and the center tap  192 , the power transformer  116  produces 220-240 VAC for powering the at least one vehicle load  210 .  
         [0023]    In addition, the opened third contact  126  opens the circuit associated with the second power receptacle  104 . Consequently, if the second power receptacle  104  is connected to the second shore power source  108 , the coil  150  of the second AC contactor  114  cannot be energized. Thus, the second power receptacle  104  is electrically disabled when the first power receptacle  102  is in use.  
         [0024]    Further, when the first power receptacle  102  is connected to the first shore power source  106 , current is also supplied to the signal transformer  118 . The second transformer transforms the 110-120 VAC to a 12 VAC signal, which may be supplied to the ECM  530 . The ECM  530  may be programmed such that when the 12 VAC signal is received, the ECM knows that the utility power input is 110-120 VAC and thus limits the usable power to about 1.5 kilowatts.  
         [0025]    Alternatively, the shore power interface  100  may be connected to the second shore power source  108  providing 220-240 VAC via the second power receptacle  104 . As long as the first power receptacle  102  is not connected to the first shore power source  106 , as explained above, a current is fed to the coil  150  of the second AC contactor  114 . The current energizes the coil  150 , causing the rod  160  and associated contacts  152 ,  154 ,  156 ,  158  to move from a first position to a second position in a direction toward the coil  150 . In the second position, the normally-closed third contact  156  is opened and the normally-opened first and second contacts  152 ,  154  are closed. A circuit is then formed that provides a flow of current between the hot wires  400 ,  410  of the second power receptacle  104  via wire  412 , first input  164 , first contact  152 , first output  174 , wires  506 ,  502 , the first and second ends  190 ,  194  of the power transformer  116 , wire  508 , second output  176 , second contact  154 , second input  166 , and wire  404 . With a transformer ratio of 1:1 for voltage between the first and second ends  190 ,  194 , the power transformer  116  produces 220-240 VAC for powering the at least one vehicle load  210 .  
         [0026]    In addition, the opened third contact  156  opens the circuit associated with the first power receptacle  102 . Consequently, if the first power receptacle  102  is connected to the first shore power source  106 , the coil  120  of the first AC contactor  112  cannot be energized. Thus, the first power receptacle  102  is electrically disabled when the second power receptacle  104  is in use.  
         [0027]    Further, when the second power receptacle  104  is connected to the second shore power source  108 , current is not supplied to the signal transformer  118 . The ECM  530  may be programmed such that when no 12 VAC signal is received, the ECM knows that the utility power input, if any, is 220-240 VAC and thus does not limit the usable power as with the 110-120 VAC input.  
         [0028]    It will be apparent to those skilled in the art that various modifications and variations can be made to the shore power interface of the present invention without departing from the scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only.