Patent Publication Number: US-8123537-B2

Title: Device for preventing unauthorized connection to outlet

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2010-37218, filed on Feb. 23, 2010, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE ART 
     The present invention relates to a device for preventing unauthorized connection of a plug to an outlet. 
     Automobile manufacturers are developing electric vehicles (including hybrid vehicles) to reduce exhaust emissions from vehicles. Such a vehicle uses a motor as a drive source. The motor is powered by a battery. Whenever the state of charge of the battery becomes low, the user of the electric vehicle must charge the battery with a charger that is installed in a household or a charging station. Charging systems that are easy for a user to use have been disclosed (for example, Japanese Laid-Open Patent Publication No. 9-161898). The prior art charging system includes a power feeding connector, which is arranged on the distal end of a charging cable connected to, for example, a household outlet for a commercial power supply. When the user is at home, the user connects the power feeding connector to a power receiving connector of the vehicle to charge the vehicle battery with commercial power. 
     SUMMARY OF THE INVENTION 
     Although fast charging technology is being developed, the time required to charge the battery of an electric vehicle is still much longer than that required to refuel a gasoline engine vehicle. For example, when a user charges the battery of an electric vehicle at home without using a quick charger, the user plugs the power feeding connector to a household outlet. Then, the user connects the power feeding connector to the power receiving connector to start charging the battery of the electric vehicle. The electric vehicle is left in this state over a long period of time. 
     The charging cable has a basal end to which a connection plug is attached. The plug is connected to a power outlet. A typical power outlet allows for connection of various types of electric appliances. Thus, when the vehicle battery is being charged, for example, an unauthorized person may disconnect the plug of the charging cable from the power outlet and connect the plug of another electrical appliance to steal electricity. 
     One aspect of the present invention is an unauthorized connection prevention device for use with an outlet. The outlet is electrically connectable to a connection plug arranged on a basal end of a charging cable that supplies commercial power to a power receiving connector. The unauthorized connection prevention device includes a verification circuit that performs verification to determine whether or not an authorized operator is electrically connecting the connection plug to the outlet. A lock mechanism switches, in accordance with a result of the verification performed by the verification circuit, between an unlocked state, which permits connection of the connection plug to an outlet port that is electrically connected to the outlet, and a locked state, which prohibits connection of the connection plug to the outlet port. 
     Another aspect of the present invention is an outlet unit connectable to a conventional power outlet and to a connection plug arranged on a basal end of a power feeding plug that supplies commercial power to a power receiving connector. The outlet unit includes an outlet port connectable to a plug terminal of the connection plug, a verification circuit that performs verification allowing for determination of whether an authorized operator is performing an operation for connecting the connection plug to the outlet unit, a lock mechanism switches, in accordance with a result of the verification performed by the verification circuit, between an unlocked state, which permits connection of the connection plug to the outlet port, and a locked state, which prohibits connection of the connection plug to the outlet port, and a coupling structure that connects the outlet unit to the conventional power outlet. The outlet unit prevents an unauthorized person from disconnecting the outlet unit from the conventional power outlet in an unauthorized manner. 
     Further aspect of the present invention is an electricity antitheft system for a commercial power outlet. The electricity antitheft system includes an outlet unit fastened to the commercial power outlet in an irremovable manner, a connection plug including a plug terminal connectable to an outlet port of the outlet unit and capable of performing wireless communication with the outlet unit, and an electronic key capable of performing wireless communication with the outlet unit. The outlet unit includes a control unit that performs wireless communication with the connection plug to determine whether or not the connection plug is authorized and performs wireless communication with the electronic key to determine whether or not the electronic key is authorized, and a lock bar controlled and driven by the control unit and moved between a retraction position, in which the lock bar is retracted into the outlet unit, and a projection position, in which the lock bar is projected out of the outlet unit from near the outlet port so that the lock bar blocks access to the outlet port by the plug terminal. The control unit moves the lock bar to the retraction position when determining that at least one of the connection plug and the electronic key is authorized. The control unit moves the lock bar to the projection position when determining that the connection plug and the electronic key are both unauthorized. 
     Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
         FIG. 1  is a block diagram of a vehicle and a charging system; 
         FIG. 2  is a perspective view showing a power feeding cable unit and an outlet unit that is connected to an outlet; 
         FIG. 3  is a side view showing the outlet unit in a locked state; 
         FIG. 4  is a side view showing the outlet unit in an unlocked state; 
         FIG. 5  is a perspective view showing the outlet and outlet unit; 
         FIG. 6  is a perspective view showing the outlet unit coupled to the outlet; and 
         FIG. 7  is a perspective view showing an embedment type outlet unit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A device for preventing unauthorized connection to an outlet according to one embodiment of the present invention will now be discussed. 
     Referring to  FIG. 1 , a plug-in hybrid vehicle  1  includes drive wheels  2  and a hybrid system, which uses an engine and a motor independently or in combination as a drive source for driving the drive wheels  2 . The hybrid system  3  operates in a mode using only the engine to drive the drive wheels  2 , a mode using the motor while generating electric power with the engine to drive the drive wheels  2 , a mode using both the engine and the motor to drive the drive wheels  2 , and a mode using only the motor to drive the drive wheels  2 . The vehicle  1  is one example of a master device. 
     The hybrid system  3  is connected to a battery  4 , which supplies the motor with power. In addition to being charged by the power generated by the engine, the battery  4  is chargeable by an external power supply of the vehicle  1  using, for example, nighttime power supplied from a household outlet  50 . The plug-in hybrid vehicle  1  is capable of traveling with just the motor over a longer distance than a conventional hybrid vehicle. This reduces the frequency of engine operation. 
     An electronic key system  70  is installed in the vehicle  1  so that vehicle operations such as the locking and unlocking of the doors can be performed without the driver actually operating a vehicle key. The electronic key system  70  uses an electronic key  80  as a vehicle key. The electronic key  80  is capable of transmitting a unique ID code through wireless communication. In the electronic key system  70 , the vehicle  1  transmits an ID code response request signal Srq. In response to the request signal Srq, the electronic key  80  sends back an ID code signal Sid, which includes its ID code, to the vehicle  1  through narrowband wireless communication. When the ID code of the electronic key  80  conforms to an ID code of the vehicle  1 , the electronic key system  70  permits or performs the locking and unlocking of the doors. The electronic key system  70  is one example of a wireless authentication system. The electronic key  80  is one example of a communication terminal. 
     The electronic key system  70  will now be described. The vehicle  1  includes a verification electronic control unit (ECU)  71 , which verifies the ID code in the ID code signal Sid returned from the electronic key  80  through narrowband wireless communication. The verification ECU  71  is connected to a vehicle exterior low frequency (LF) transmitter  72 , a vehicle interior LF transmitter  73 , and an ultrahigh frequency (UHF) receiver  74 . The LF transmitter  72  is arranged in each door of the vehicle  1  and transmits wireless signals out of the vehicle in the LF band. The LF transmitter  73  is arranged in the vehicle under the floor or the like and transmits wireless signals to the interior of the vehicle  1  in the LF band. The UHF receiver  74  is arranged in the rear of the vehicle body or the like to receive wireless signals in the UHF band. The verification ECU  71  includes a memory  71   a , which stores an ID code as a unique key code. 
     The electronic key  80  includes a communication control unit  81 , which functions to perform wireless communication with the vehicle  1  in compliance with the electronic key system  70 . The communication control unit  81  includes a memory  81   a , which stores an ID code as a unique key code. The communication control unit  81  is connected to an LF receiver  82 , which receives signals in the LF band, and a UHF transmitter  83 , which transmits signals in the UHF band in accordance with commands from the communication control unit  81 . 
     The verification ECU  71  intermittently transmits a request signal Srq in the LF band from the vehicle exterior LF transmitter  72  at a predetermined controlled timing and forms a vehicle exterior communication area near the vehicle  1 . When the electronic key  80  enters the vehicle exterior communication area and receives the request signal Srq with the LF receiver  82 , the electronic key  80  sends back an ID code signal Sid including the ID code in the UHF band from the UHF transmitter  83  in response to the request signal Srq. When receiving the ID code signal Sid with the UHF receiver  74 , the verification ECU  71  compares the ID code registered in its memory  71   a  with the ID code of the electronic key  80  to perform ID verification (vehicle exterior verification) on the electronic key  80 . When vehicle exterior verification is successful, the verification ECU  71  permits or performs locking and unlocking of the doors with a door lock (not shown). 
     When recognizing that the doors have been unlocked upon successful vehicle exterior verification and that the driver has opened a door and entered the vehicle  1 , the verification ECU  71  transmits a request signal Srq from the vehicle interior LF transmitter  73  to form a vehicle interior communication area throughout the vehicle interior. The electronic key  80  enters the vehicle interior communication area and returns an ID code signal Sid in response to the request signal Srq. When the UHF receiver  74  receives the ID code signal Sid, the verification ECU  71  verifies the ID code of the electronic key  80  with the ID code registered in the memory  71   a  to perform ID verification (vehicle interior verification) on the electronic key  80 . When vehicle interior verification is successful, the verification ECU  71  permits the starting of the hybrid system. 
     A plug-in vehicle battery charging system  10  will now be discussed. The charging system  10  charges the battery  4  of the vehicle  1  with an external power supply such as an outlet  50 , which is arranged in, for example, a household or a commercial facility. The external power supply may be, for example, a commercial power grid that supplies 200 V of AC power. As shown in  FIG. 1 , the charging system  10  includes a charging cable  12 , which has one end defining a power feeding plug  11  and another end defining a connection plug  13 . The connection plug  13  includes plug terminals  14  connectable to outlet ports  51  of the outlet  50 . The charging cable  12  includes a charging switch  15 . In this specification, the power feeding plug  11 , the charging cable  12 , and the connection plug  13  are referred to as a charging cable unit. 
     To charge the battery  4  of the hybrid vehicle  1 , the power feeding plug  11  is connected to a power receiving connector  5  of the vehicle  1 . The power receiving connector  5 , which receives the power feeding plug  11 , is installed, for example, in the front side wall of the vehicle body in the same manner as a fuel tank opening of a gasoline vehicle. The power receiving connector  5  uses a converter  6  to convert the AC power from the power feeding plug  11  to DC voltage and charges the battery  4  of the vehicle  1  with the DC voltage. When the power feeding plug  11  is inserted into the power receiving connector  5  and the ID code of the electronic key  80  carried by the user is successfully verified, the power receiving connector  5  is permitted to charge the battery  4 . The vehicle exterior communication area is formed around the entire vehicle  1 . Further, the vehicle  1  constantly generates a key inquiry (transmits a request signal Srq) so as to perform polling. Thus, ID verification is performed as long as the user is carrying the electronic key  80 . The user does not have to manually operate the electronic key. 
     The vehicle  1  includes a charge ECU  75 , which executes charging-related control. The charge ECU  75  is communicable with the verification ECU  71  through an in-vehicle local area network (LAN) and is capable of checking the verification ECU  71  for ID verification results. The charge ECU  75 , which is connected to the power receiving connector  5 , detects connection of the power feeding plug  11  to the power receiving connector  5 . When the power feeding plug  11  is connected to the power receiving connector  5  and the electronic key  80  is successfully verified, the charge ECU  75  permits charging. In the illustrated example, the power receiving connector  5  includes a locking device  7 , which prevents unauthorized disconnection of the power feeding plug  11  from the power receiving connector  5 . 
     The outlet  50  is connected to an outlet unit  20 . When the connection plug  13  is registered to the outlet unit  20  and thus authorized, the outlet unit  20  permits connection to the outlet unit  20 . However, when the connection plug  13  is one that is not registered and thereby is not granted connection permission, the outlet unit  20  prohibits connection to the outlet unit  20 . Further, an unauthorized disconnection prevention mechanism, which will be described later, functions to prevent disconnection of the outlet unit  20  from the outlet  50  unless the authorized electronic key  80  is carried by the person attempting disconnection. 
     The outlet unit  20  includes a lock mechanism  40 , which permits connection of only the authorized connection plug  13  to the outlet unit  20 . The lock mechanism  40 , which is arranged near an output terminal or outlet ports  22  of the outlet unit  20 , includes a lock bar  41  and a solenoid  42 . The lock bar  41  is movable between a retraction position and a projection position. The solenoid  42  drives the lock bar  41 . The solenoid  42  is a keep type solenoid. When current flows to the solenoid  42  in the forward direction for a short period of time, the lock bar  41  is moved to the retraction position and retracted into the outlet unit  20 . In this state, the outlet unit  20  is unlocked (plug connection permission state). After current stops flowing in the forward direction, the lock bar  41  remains at the retraction position. Thus, the lock mechanism  40  remains in an unlocked state (refer to  FIG. 4 ). In contrast, when current flows to the solenoid  42  in the reverse direction for a short period of time, the lock bar  41  is moved to a projection position and projected out of the outlet unit  20 . In this state, the outlet unit is locked (plug connection prohibition state). After current stops flowing in the reverse direction, the lock bar  41  remains at the projection position. Thus, the lock mechanism  40  remains in a locked state (refer to  FIG. 3 ). The solenoid  42  functions as an electric restriction mechanism driven by an electric drive source. The lock bar  41  is referred to as a restriction member. 
     When the connection plug  13  is not connected to the outlet unit  20 , the lock mechanism  40  is in the locked state. The lock bar  41 , which is located at the projection position in the locked state, prevents an unauthorized person or the like from electrically connecting a non-registered connection plug, which has not been granted connection permission, to the outlet ports  22  of the outlet unit  20 . When it is determined that an authorized user is connecting the connection plug  13  to the outlet unit  20 , the lock mechanism  40  switches to the unlocked state. When the user is unauthorized, the lock mechanism  40  remains in the lock state. 
     As shown in  FIG. 2 , the outlet unit  20  has a rear surface, from which connection terminals  21  extend, and a front surface, in which the outlet ports  22  are formed. The connection terminals  21  on the rear surface are connectable to the outlet ports  51  of the outlet  50 , which is arranged in a household or a commercial facility. The outlet ports  22  on the front surface are capable of receiving the plug terminals  14  of the connection plug  13 . The outlet  50  to which the outlet unit  20  is connectable may be a conventional one. 
     A release switch  23  is arranged in the outer surface of the outlet unit  20 . The release switch  23  is operated when unlocking the lock mechanism  40 , that is, when connecting the connection plug  13  to the outlet ports  22  of the outlet unit  20 . The release switch  23  is, for example, a momentary type push switch. In the illustrated example, one condition for unlocking the lock mechanism  40  is the release switch  23  is pushed. The release switch  23  is one example of a mechanical operation unit. 
     As shown in  FIG. 1 , the outlet unit  20  includes a lock ECU  31 , which manages the operation of the outlet unit  20 . The lock ECU  31  is connected to the solenoid  42  and detection sensor  43 , which are arranged in the lock mechanism  40 . The detection sensor  43  monitors whether or not the connection plug  13  is connected to the outlet unit  20 . When detecting disconnection of the connection plug  13  from the outlet unit  20 , the detection sensor  43  sends a detection signal to the lock ECU  31 . When receiving the detection signal and determining that the connection plug  13  has been disconnected from the outlet unit  20 , the lock ECU  31  switches the lock mechanism  40  to the locked state. 
     The outlet unit  20  also includes an outlet verification system  30 , which verifies that the connection plug  13  is the authorized plug. In the illustrated example, the outlet verification system  30  includes an immobilizer amplifier  36 , which is similar to that used in a vehicle immobilizer system, and the lock ECU  31 , which is connected to the immobilizer amplifier  36 . The outlet verification system  30  performs near field communication with the connection plug  13  and performs ID verification on the connection plug  13 . The connection plug  13  includes a transponder  16 . A transponder code such as that used in a vehicle immobilizer system is registered to the transponder  16 . The transponder  16  exchanges near field communication signals with the immobilizer amplifier  36 . The outlet verification system  30  is also referred to as an outlet wireless authentication system. The transponder  16  is one example of an authentication tag. 
     The lock ECU  31  functions as a control unit of the outlet verification system  30 . The lock ECU  31  is connected to the immobilizer amplifier  36 . The lock ECU  31  includes a memory  31   a , which stores a transponder code. In the lock ECU  31 , a verification unit  31   b  compares the transponder code stored in the memory  31   a  with the transponder code of the transponder  16  to perform ID verification on the connection plug  13  (also referred to as plug ID verification). The verification unit  31   b  is one example of a verification circuit. The verification unit  31   b  and a lock control unit  31   c  are also referred to as an authentication circuit. 
     When the release switch  23  is pushed, the outlet verification system  30  starts to transmit drive radio waves from the immobilizer amplifier  36 . As the user moves the connection plug  13  to the outlet unit  20  while pushing the release switch  23 , the drive radio waves transmitted from the immobilizer amplifier  36  activate the transponder  16  of the connection plug  13 . Then, the transponder  16  transmits a transponder signal, which includes a transponder code. The immobilizer amplifier  36  receives the transponder signal and provides the lock ECU  31  with the received signal. In the lock ECU  31 , the verification unit  31   b  performs plug ID verification based on the transponder code of the received signal. The plug ID verification is performed with only the connection plug  13  and does not use the electronic key  80 . Further, the plug ID verification is performed when switching the lock mechanism  40  of the outlet unit  20  to the unlocked state and when registering a non-registered connection plug to the outlet unit  20 . The immobilizer amplifier  36  forms a plug ID verification wireless communication circuit. 
     The outlet verification system  30  includes a key verification system, which performs ID verification on the electronic key  80  by communicating with the electronic key  80  in compliance with the electronic key system  70 . The key verification system is used when determining whether or not the user of the connection plug  13  is the authorized user and when connecting a non-registered plug (including a new connection plug  13 ) to the outlet unit  20 . The key verification system performs ID verification in the same manner as the electronic key system  70  and permits connection to the outlet ports  22  of the outlet unit  20  when ID verification of the electronic key  80  is successful. The key verification system corresponds to a wireless authentication system. 
     The key verification system is similar to the structure of the electronic key system  70 . The lock ECU  31  functions as a control unit of the key verification system. The lock ECU  31  is connected to an LF transmitter  32 , which transmits signals in the LF band, and a UHF receiver  33 , which receives signals in the UHF band. The memory  31   a  of the lock ECU  31  stores an ID code that is a key code unique to the verification unit  31   b.    
     The verification unit  31   b  of the lock ECU  31  intermittently transmits a request signal Srq in the LF band from the LF transmitter  32  at a predetermined controlled timing and forms a communication area near the outlet unit  20 . When the electronic key  80  enters the communication area and receives the request signal Srq with the LF receiver  82 , the electronic key  80  sends back an ID code signal Sid on the UHF band from the UHF transmitter  83  in response to the request signal Srq. The ID code signal Sid includes the ID code registered in the memory  81   a  of the electronic key  80 . When receiving the ID code signal Sid with the UHF receiver  33 , the verification unit  31   b  compares the ID code registered in the memory  31   a  with the ID code of the electronic key  80  to perform ID verification on the electronic key  80  (also referred to as electronic key ID verification). The UHF receiver  33  forms a wireless communication circuit used for communication terminal verification. 
     The lock ECU  31  includes the lock control unit  31   c , which serves as a control circuit for controlling the operation of the lock mechanism  40 . As described above, when connecting the connection plug  13  to the outlet unit  20 , the user must push the release switch  23 . When determining that the release switch  23  is being pushed, the verification unit  31   b  performs ID verification. In detail, the verification unit  31   b  first performs plug ID verification. Then, when plug ID verification is unsuccessful, the verification unit  31   b  performs electronic key ID verification. The fact that either the plug ID verification or the electronic key ID verification is successful indicates that the authorized connection plug  13  is being used or that the authorized electronic key  80  is located near the outlet unit  20 . A proper user, such as an authorized user, carries the authorized electronic key  80  or authorized connection plug  13 . However, it would be difficult for an unauthorized person to obtain the authorized electronic key  80  or authorized connection plug  13 . Accordingly, when the plug ID verification or the electronic key verification is successful, it can be assumed that the authorized user is attempting to connect a connection plug to the outlet unit  20 . Thus, when determining that plug ID verification or electronic key ID verification has been successful through communication with the verification unit  31   b , the lock control unit  31   c  permits the supply of current to the solenoid  42 . When supplied with current, the solenoid  42  generates a magnetic field to retract the lock bar  41  from the projection position into the outlet unit  20 . This switches the lock mechanism  40  to the unlocked state and allows the plug terminals  14  of the connection plug  13  to be connected to the outlet ports  22  of the outlet unit  20 . 
     When the lock control unit  31   c  communicates with the verification unit  31   b  and determines that plug ID verification and electronic key ID verification were both unsuccessful, the lock control unit  31   c  keeps the solenoid  42  deactivated. In this case, the lock bar  41  remains at the projection position. Thus, the plug terminals  14  of the connection plug  13  cannot be connected to the outlet ports  22  of the outlet unit  20 . The solenoid  42  is normally deactivated. The solenoid  42  is activated only when the release switch  23  is operated and the plug ID verification or electronic key ID verification is successful. 
     When the connection plug  13  is disconnected from the outlet unit  20 , the lock control unit  31   c  supplies the solenoid  42  with current. The solenoid  42  generates a magnetic field in the reverse direction and moves the lock bar  41  from the retraction position to the projection position. This shifts the lock mechanism  40  to the locked state. To connect the disconnected connection plug  13  again to the outlet ports  22  of the outlet unit  20 , plug ID verification or electronic key verification must be successful. 
     When plug ID verification is unsuccessful but electronic key ID verification is successful, a non-registered connection plug may be connected to the outlet unit  20 . In detail, the user, who is carrying an authorized key, namely, the electronic key  80  that corresponds to the outlet unit  20 , pushes the release switch  23 . When the verification unit  31   b  determines that the release switch  23  has been pushed, the verification unit  31   b  performs electronic key ID verification. Since the electronic key  80  is authorized, the electronic key ID verification performed by the verification unit  31   b  is successful, and the lock control unit  31   c  switches the lock mechanism  40  to the unlocked state. This allows for the non-registered connection plug to be connected to the outlet ports  22  of the outlet unit  20 . The lock control unit  31   c  functions as a non-registered plug connection circuit. 
     The lock ECU  31  includes a plug registration unit  31   d , which serves as a registration circuit that registers non-registered connection plugs. The procedures for registering a non-registered connection plug to the outlet unit  20  will now be described. First, the plug registration unit  31   d  is activated by the electronic key  80 , for example. In this state, plug ID verification is performed with the transponder of the non-registered connection plug to obtain the transponder code of the non-registered connection plug. The plug registration unit  31   d  registers the obtained transponder code to the memory  31   a . This registers the connection plug as an authorized connection plug to the outlet unit  20 . Subsequent to the registration, the connection plug becomes connectable to the outlet unit  20  after undergoing successful ID verification even when the electronic key  80  is not present. 
     A combination of the outlet unit  20 , the connection plug  13 , and the electronic key  80  may be referred to as an electricity antitheft system. 
     A structure and method for coupling the outlet unit  20  to the outlet  50  will now be discussed with reference to  FIGS. 5 and 6 . 
     As shown in  FIG. 5 , a household outlet  50  is arranged in a wall of a building for a household or the like. The connection terminals  21  of the outlet unit  20  are plugged into outlet ports  51  of the household outlet  50  to connect the outlet unit  20  to the outlet  50 . 
     As shown in  FIG. 6 , a fastening plate  24  is arranged on the rear surface of the outlet unit  20  to fasten the outlet unit  20  to a wall  9 , which includes the outlet. The fastening plate  24  is a discrete member. The fastening plate  24  includes insertion holes  24   a , which have the same size as the outlet ports  51 . Further, the fastening plate  24  includes two hooks  26 , which are formed in correspondence with two sockets  27  formed in the rear surface of the outlet unit  20 . 
     The insertion holes  24   a  of the fastening plate  24  are first aligned with the outlet ports  51 . In this state, the fastening plate  24  is fixed by screws  25  to the wall  9 . 
     Subsequently, the connection terminals  21  of the outlet unit  20  are aligned with the insertion holes  24   a , and the rear surface of the outlet unit  20  is pushed against the fastening plate  24 . This forces the connection terminals  21  into the outlet ports  51  of the outlet  50 , hooks the hooks  26  to the sockets  27 , and fastens the outlet unit  20  to the wall  9 . When the outlet unit  20  is fastened to the wall  9 , it is preferable that the hooks  26  and sockets  27  be hidden in the rear surface of the outlet unit  20 . The rear surface (sockets  27 ) of the outlet unit  20  and the fastening plate (hooks  26 ) form a coupling structure. 
     The outlet unit  20  includes an interlocking mechanism (not shown) that prevents separation of the hooks  26  from the sockets  27 . The interlocking structure permits removal of the hooks  26  from the sockets  27  under the condition that electronic key verification has been successful. 
     The operation for connecting the connection plug  13  to the outlet unit  20  to charge the battery  4  with the power feeding plug  11  and the function of the lock mechanism  40  will now be discussed with reference to  FIGS. 2 to 4 . 
     When the connection plug  13  is not connected to the outlet unit  20 , the lock mechanism  40  is in the locked state. When the connection plug  13  was previously disconnected from the outlet ports  22 , the lock mechanism  40  was switched to the locked state. Thus, the operator operates the release switch  23  of the outlet unit  20 . When the authorized user is carrying the authorized electronic key  80 , electronic key ID verification is successful. When the lock control unit  31   c  checks the verification unit  31   b  and confirms that electronic key ID verification has been successful, the lock control unit  31   c  supplies current to the solenoid  42  to retract the lock bar  41  into the outlet unit  20  and switch the lock mechanism  40  to the unlocked state. This allows for the operator to connect the plug terminals  14  of the connection plug  13  to the outlet ports  22  of the outlet unit  20  (refer to  FIG. 4 ). 
     Then, the operator connects the power feeding plug  11  to the power receiving connector  5 . The locking device  7  of the power receiving connector  5  prevents unauthorized disconnection of the power feeding plug  11  from the power receiving connector  5 . When the charging switch  15  is switched on in this holding state, the power feeding plug  11  starts charging the battery  4  through the power receiving connector  5 . 
     For example, an unauthorized person, who is carrying an authorized connection plug or a non-registered connection plug, may approach the outlet ports  22  of the outlet unit  20 . In such a case, the lock bar  41  is projected from the outlet unit  20  so that the lock bar blocks access to the outlet port  22  by a plug terminal of a non-registered connection plug. The unauthorized person is not aware of the release switch  23 . Thus, the release switch  23  is not operated. In this case, neither the plug ID verification nor the key verification is started. Since the lock bar  41  abuts the authorized or non-registered connection plug, the unauthorized person cannot connect the authorized or non-registered connection plug to the outlet unit  20  (refer to  FIG. 3 ). This prevents unauthorized electrical connection of the outlet unit  20  to the outlet  50 . 
     For example, an unauthorized person that is aware of the operation of the release switch  23  but not carrying the electronic key  80  may attempt to connect a non-registered connection plug to the outlet unit  20 . When the release switch  23  is operated, the verification unit  31   b  starts the plug ID verification. However, the plug ID verification performed on the non-registered connection plug is unsuccessful. Then, the verification unit  31   b  starts key verification. However, the unauthorized person is not carrying the electronic key  80 . Thus, the key verification is unsuccessful. Since the plug ID verification and key verification are both unsuccessful, the lock control unit  31   c  keeps the solenoid  42  deactivated. As a result, the lock mechanism  40  remains in the locked state in which the lock bar  41  blocks access to the outlet port  22  by a plug terminal of a non-registered connection plug. In this manner, the outlet unit  20  prevents unauthorized electrical connection of the connection plug to the outlet  50 . 
     When the charging of the battery  4  is completed, the operator unlocks the locking device  7  to disconnect the power feeding plug  11  from the power receiving connector  5 . 
     Then, when the detection sensor  43  detects disconnection of the connection plug  13  from the outlet unit  20 , the lock control unit  31   c  supplies current to the solenoid  42  to project the lock bar  41  out of the outlet unit  20  and switch the lock mechanism  40  to the locked state. This prevents an unauthorized person from connecting a non-registered connection plug in an unauthorized manner to the outlet unit  20 . The operator then stores the charging cable unit, which is disconnected from the power receiving connector  5  and the outlet unit  20 , in the vehicle, for example. 
     The procedures for connecting a non-registered connection plug when the operator is carrying the authorized electronic key  80  will now be discussed. The operator first pushes the release switch  23  while carrying the electronic key  80 . In this case, after the plug ID verification is performed, the verification unit  31   b  performs electronic ID verification, which is successful. When the lock control unit  31   c  recognizes that the electronic key ID verification was successful, the lock control unit  31   c  switches the lock mechanism  40  to the unlocked state. This allows for the non-registered connection plug to be connected to the outlet ports  22  of the outlet unit  20 . Thus, the operator can connect the non-registered connection plug to the outlet ports  22  of the outlet unit  20 . 
     The procedures taken by an operator carrying the authorized electronic key  80  to register a new non-registered connection plug to the outlet unit  20  will now be described. The operator who is carrying the electronic key  80  first brings the non-registered connection plug near the outlet unit  20  and, for example, operates a button (not shown) on the electronic key  80  following predetermined registration procedures to transmit a registration request signal from the electronic key  80  to the outlet unit  20 . When the UHF receiver  33  receives the registration request signal, the plug registration unit  31   d  starts the registration operation. The plug registration unit  31   d  transmits drive radio waves from the immobilizer amplifier  36  to activate the transponder of the non-registered connection plug and obtain the transponder code of the non-registered connection plug. 
     Here, the plug registration unit  31   d  checks whether or not the newly obtained transponder code has already been registered. When the transponder code has not yet been registered, the new transponder code obtained by the verification unit  31   b  is registered to the memory  31   a . Thus, the transponder code of the new connection plug is registered to the outlet unit  20 . The newly registered connection plug is then connectable to the outlet unit  20  without the need for the electronic key  80  from the next time. 
     As described above, the outlet unit  20  of the present embodiment includes the verification unit  31   b  and the lock mechanism  40 . The verification unit  31   b  is provided with a verification function, and the lock mechanism  40  includes the lock bar  41  provided with a locking function. The connection plug  13  is not directly connected to the household outlet  50  but indirectly connected via the outlet unit  20  to the household outlet  50 . When the authorized user connects the connection plug, ID verification is successful for at least one of the connection plug and the electronic key. This activates the solenoid  42  and switches the lock mechanism  40  to the unlocked state. In this state, the connection plug is electrically connectable to the outlet  50  via the outlet unit  20 . 
     When an unauthorized person attempts to connect a connection plug, the connection plug and the electronic key both do not succeed ID verification. Thus, the solenoid  42  remains deactivated, the lock mechanism  40  remains in the locked state, and the connection plug cannot be connected to the outlet unit  20 . Accordingly, the connection plug cannot be electrically connected to the outlet  50 . This prevents an unauthorized person from connecting an unauthorized connection plug to the outlet  50  and stealing electricity. 
     The embodiment discussed above has the advantages described below. 
     (1) The outlet unit  20 , which is provided with the verification function and the lock function (unauthorized connection prevention function), is fastened to the outlet  50 . This prevents an unauthorized person from connecting a connection plug to the outlet  50  in an unauthorized manner. 
     (2) When the detection sensor  43  detects disconnection of the connection plug  13  from the outlet unit  20 , the lock mechanism  40  is automatically switched to the locked state. Thus, when disconnecting the connection plug  13  from the outlet unit  20 , the lock mechanism  40  is prevented from being left in the unlocked state. 
     (3) Unauthorized connection of the connection plug  13  is prevented by a simple structure that projects the lock bar  41  out of the outlet unit  20  so that the connection plug  13  cannot be connected to the outlet unit  20 . Further, the operator can visually recognize the locked state by looking at the projected lock bar  41 . 
     (4) The connection plug  13  includes the transponder  16 , and the connection plug  13  performs ID verification with the outlet unit  20 . Thus, as long as the authorized connection plug  13  is held in person, the connection plug  13  can be freely coupled to the outlet unit  20 . 
     (5) The result of the ID verification performed on the electronic key  80  (electronic key ID verification) is used to determine whether or not the authorized operator is connecting the connection plug  13 . This allows for determination of whether or not the outlet  50  is being used in an unauthorized manner and makes it further difficult for an unauthorized connection plug to be connected to the outlet  50 . 
     (6) The conventional electronic key  80  of the electronic key system  70  installed in the vehicle  1  is used as a communication terminal by the outlet verification system  30 . This prevents unauthorized connection of the connection plug  13  to the outlet  50  without using a separate communication terminal dedicated for the outlet verification system  30 . 
     (7) The lock mechanism  40  is switched to the unlocked state when ID verification performed on the electronic key  80  (electronic key ID verification) is successful. Thus, as long as the authorized electronic key  80  is carried in person, even a non-registered connection plug can be connected to the outlet unit  20 . In this manner, the outlet unit  20  allows for use of a connection plug that does not include the transponder  16  and is thereby versatile. 
     (8) The outlet unit  20  includes the plug registration unit  31   d . Thus, a new connection plug that includes the transponder  16  can be used. 
     (9) The outlet unit  20  is an integrated unit that may be connected to various types of the household outlet  50  at any time. 
     (10) The operation of the release switch  23  is one condition for switching the lock mechanism  40  to the unlocked state. Thus, the connection plug  13  is connectable to the outlet unit  20  only when the authorized user intentionally operates the release switch  23 . This eliminates the need to perform unnecessary ID verification and saves power. 
     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms. 
     Instead of the keep solenoid  42 , a pull solenoid that pulls the lock bar  41  only when performing unlocking may be used. 
     The lock bar  41  may be driven with a drive source other than a solenoid such as a motor. 
     Instead of the lock mechanism  40  that includes the lock bar  41  and the solenoid  42 , for example, a mechanical operation member such as a lever that is manually operable only when the ID verification performed by the verification unit  31   b  is successful may be used to prevent connection of the connection plug  13  to the outlet unit  20 . 
     The structure of the lock mechanism  40  is not limited as long as the plug terminals  14  of the connection plug  13  can be prevented from being connected to the outlet ports  22  of the outlet unit  20 . For example, the lock mechanism  40  may include a shutting member that at least partially shuts the outlet ports  22  when the lock mechanism  40  is in the locked state. 
     In the above-discussed embodiment, the fastening plate  24  of the outlet unit  20  is fastened to the wall  9  that includes the outlet  50 , with the hooks  26  hooked to the sockets  27 . However, a different structure may be used to fasten the outlet unit  20  to the outlet  50 . For example, a structure that includes a hook, which is hooked to the household outlet  50 , and a lock mechanism, which locks the hook, may be used to restrict unauthorized disconnection of the outlet unit  20 . 
     In the above-discussed embodiment, the outlet unit  20  is connected to the outlet  50 . However, the outlet  50  may be eliminated, and the outlet unit  20  may be directly connected to commercial power supply cable  53  as shown in  FIG. 7 . In this example, the outlet unit  20  is of an embedment type and its front surface is exposed from the wall  9 . 
     In the above-discussed embodiment, the lock ECU  31  maintains the lock mechanism  40  in the locked state when the release switch  23  is operated and ID verification is unsuccessful. However, the verification unit  31   b  may perform ID verification again when the release switch is being operated. In more detail, when the release switch  23  is operated and ID verification is unsuccessful, a further ID verification may be performed. 
     In the above-discussed embodiment, the connection plug  13  includes the transponder  16  but is not limited to such a structure. For example, an antenna, transmitter, and receiver similar to those of the electronic key  80  may be installed in the connection plug  13 . 
     In the above-discussed structure, the transponder  16  may be eliminated from the connection plug  13 . 
     In the above-discussed embodiment, the electronic key system  70  and the outlet verification system may use radio waves of frequencies other than LF and UHF. Further, the frequency of the radio waves transmitted from the vehicle  1  to the electronic key  80  may be the same as or different from the frequency of the radio waves transmitted from the electronic key  80  to the vehicle  1 . 
     In the above-discussed embodiment, instead of performing ID verification on the electronic key  80 , the operator may be determined as being authorized through other processes such as biometric authentication. 
     The embodiment discussed above is applied to the plug-in hybrid vehicle  1  but also may be applied to an electric vehicle or the like. Further, the present invention is not limited to vehicles and may be applied a different apparatus or machine. 
     In the above-discussed embodiment, the lock mechanism  40  of the present example is not limited to buildings and may be applied to any location as long as there is an apparatus or machine that includes an outlet  50 . 
     The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.