Abstract:
A power supplying plug lock device attachable to an operation arm of a power supplying plug, the operation arm operable to fix the power supplying plug to an inlet, is configured to restrict movement of the operation arm to prevent unauthorized removal of the power supplying plug. The power supplying plug lock device is externally attachable to the operation arm when an authentication member accomplishes authentication. A restriction member moves from an open position to a close position to engage with the operation arm when the power supplying plug lock device is attached to the operation arm. A position holding mechanism shifts to a lock state in cooperation with the movement of the restriction member to the close position, thereby holding the restriction member at the close position. The position holding mechanism maintains the lock state until the authentication member again accomplishes authentication.

Description:
FIELD 
       [0001]    The present invention relates to a power supplying plug lock device that prevents unauthorized removal of a power supplying plug. 
       BACKGROUND 
       [0002]    People have become more aware of environmental problems. Thus, vehicles having low carbon dioxide emissions, such as hybrid vehicles and electric vehicles, have become popular. In such a vehicle, a battery powers a motor to produce torque that drives the vehicle. When the vehicle travels over a long distance and the state of charge of the battery becomes low, the battery has to be charged (refer to, for example, patent literature 1). In the system of patent literature 1, a power supplying plug, which is arranged on the distal end of a charging cable, is connected to a vehicle to charge a vehicle battery. 
         [0003]    Battery charging involves electrolytic reactions of compounds and ions in battery cells of the battery. This relatively lengthens the charging time. Thus, a user would leave the vehicle when the battery is being charged. In such a case, someone may remove the power supplying plug from the vehicle and steal electricity. It is thus desirable that a vehicle including a rechargeable battery be provided with a power supplying plug lock device that prevents unauthorized removal of a power supplying plug from the vehicle. 
       CITATION LIST 
     Patent Literature 
     [PTL 1] 
     Japanese Laid-Open Patent Publication No. 9-161898 
     SUMMARY 
     Technical Problem 
       [0004]    A padlock is one example of a power supplying plug lock device that locks a power supplying plug to an inlet of a vehicle with a lock arm. However, with such a lock device, when locking the power supplying plug, the user is required to remove a shackle from the padlock and then fit the shackle back into a padlock hole. Thus, locking with the padlock is burdensome. Further, padlocks are widely available in the market. Thus, when charging is performed without locking the power supplying plug, someone may use a commercially available padlock to lock the power supplying plug without permission. 
         [0005]    The present invention provides a power supplying plug lock device that allows for easy locking of a power supplying plug to an inlet. 
       Solution to Problem 
       [0006]    One aspect of the present invention is a power supplying plug lock device that restricts operation of an operation arm, which is used to fix a power supplying plug to an inlet, to prevent unauthorized removal of the power supplying plug. The power supplying plug lock device includes an authentication member used for authentication, a restriction member that is engageable with the operation arm, and a position holding mechanism that is able to hold the restriction member at a position engaged with the operation arm. The restriction member is configured to move from an open position to a close position to engage with the operation arm by attachment of the power supplying plug lock device to the operation arm. The position holding mechanism is configured to shift from an unlock state to a lock state in cooperation with the movement of the restriction member from the open position to the close position thereby holding the restriction member at the close position and to maintain the lock state until the authentication member accomplishes authentication. 
         [0007]    In this structure, the power supplying plug may be locked to the inlet just by attaching the power supplying plug lock device to the operation arm. This allows for the power supplying plug to be locked by performing a simple task. Further, the power supplying plug lock device of this structure has to be possessed to lock the power supplying plug. This prevents unauthorized locking by an unauthorized person. 
         [0008]    In the power supplying plug lock device, the restriction member may be one of two restriction members arranged to move toward and away from each other. In this case, the position holding mechanism may be configured to be shifted to the lock state when the two restriction members are both moved. 
         [0009]    In this structure, the power supplying plug lock device does not switch to a lock state even when the one of the two restriction members is inadvertently pushed. This prevents inadvertent switching to a lock state. 
         [0010]    In the power supplying plug lock device, the position holding mechanism may include a movable member, a lock member, and an urging member. The movable member is movable between an unlock position and a lock position. The movable member is configured to be coupled to the authentication member at the unlock position and restrict movement of the restriction member at the lock position. The lock member is movable between a first position and a second position and is configured to permit movement of the movable member to the lock position when located at the second position. The urging member is configured to urge the movable member from the unlock position to the lock position. The movable member is configured to start movement from the unlock position to the lock position with an urging force of the urging member when the restriction member moves to the open position and fix the lock member at the second position to hold the restriction member at the close position when located at the lock position. 
         [0011]    In this structure, the power supplying plug may be locked with a simple structure that uses the movable member and the lock member. 
         [0012]    In the power supplying plug lock device, the lock member may include a fitting groove into which the movable member is fitted. Further, the restriction member may include a restriction surface that restricts, when the restriction member moves to the open position, movement of the movable member to the lock position to maintain the movable member in a state incompletely fitted to the fitting groove of the lock member. 
         [0013]    In this structure, the lock device is prevented from shifting to the lock state against the user&#39;s will before attaching the lock device to the power supplying plug. For example, the restriction surface of the restriction member maintains the movable member in an incompletely fitted state even when the user touches and slightly moves the restriction member. This prevents the lock device from being inadvertently shifted to a lock state. 
         [0014]    In the power supplying plug lock device, the movable member may be a single component. Further, the lock member may be one of two lock members fixed at the second position by the movable member. 
         [0015]    In this structure, the power supplying plug may be locked with a simple structure using one movable member and two lock members. 
         [0016]    The power supplying plug lock device may further include an unlock portion operated to release the position holding mechanism from the lock state and return the position holding mechanism to the unlock state. 
         [0017]    In this structure, by operating the unlock portion, the unlock portion may be operated to release the position holding mechanism from the lock state and shift the position holding mechanism to the unlock state. Thus, the power supplying plug lock device may easily be removed from the power supplying plug. 
         [0018]    In the power supplying plug lock device, the restriction member may include a curved guide surface that guides the movement of the restriction member when the restriction member is engaged with the operation arm. 
         [0019]    In this structure, the guide surface guides the movement of the restriction member when the power supplying plug lock device is attached to the operation arm. Thus, the power supplying plug lock device may be smoothly attached to the operation arm. 
         [0020]    In the power supplying plug lock device, the restriction member may include a separation prevention corner that prevents separation of the operation arm from the restriction member held at the close position. 
         [0021]    In this structure, the power supplying plug may be kept locked in a preferable manner. 
         [0022]    In the power supplying plug lock device, the position holding mechanism may includes a movable member, a lock member, and an urging member. The movable member is movable between an unlock position and a lock position and is configured to be coupled to the authentication member at the unlock position and restrict movement of the restriction member at the lock position. The lock member is movable between a first position and a second position and configured to permit movement of the movable member to the lock position when located at the second position. The urging member is configured to urge the movable member from the unlock position to the lock position. The movable member is configured to: start moving from the unlock position to the lock position with an urging force of the urging member when the restriction member moves to the open position; be incompletely fitted to the lock member thereby fixing the lock member at the second position when the restriction member is located at the open position; finish movement to the lock position when the restriction member moves from the open position to the close position; and be completely fitted to the lock member thereby holding the restriction member at the close position when the movable member is located at the lock position. 
         [0023]    In this structure, the lock device is prevented from shifting to the lock state against the user&#39;s will before attaching the lock device to the power supplying plug. For example, the restriction surface of the restriction member maintains the movable member in an incompletely fitted state even when the user touches and slightly moves the restriction member. This prevents the lock device from being inadvertently shifted to a lock state. Further, the power supplying plug may be kept lock in an appropriate manner as long as the movable member shifts to the completely fitted state. 
         [0024]    In the power supplying plug lock device, the unlock portion may include an unlock button operated by a user. The unlock portion switches the position holding mechanism from the lock state to the unlock state and moves the restriction member from the close position to the open position when the unlock button is operated. 
         [0025]    In this structure, the power supplying plug may easily be unlocked. 
         [0026]    In the power supplying plug lock device, the authentication member is a dial cylinder including a plurality of dials used to set an authentication number. 
         [0027]    In this structure, the dial cylinder is arranged in the power supplying plug lock device to perform authentication. Thus, the user does not have to carry a separate key. This improves convenience. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  is a schematic block diagram of a hybrid vehicle in one embodiment; 
           [0029]      FIG. 2  is a perspective view showing a power supplying plug and an inlet of a charging system in the hybrid vehicle of  FIG. 1 ; 
           [0030]      FIG. 3  is a side view showing the power supplying plug and inlet of  FIG. 2 ; 
           [0031]      FIG. 4A  is a perspective view showing a front side of a power supplying plug lock device in the hybrid vehicle of  FIG. 1 ; 
           [0032]      FIG. 4B  is a perspective view showing a rear side of the power supplying plug lock device of  FIG. 4A ; 
           [0033]      FIG. 5  is a front view showing the power supplying plug lock device in an unlock state; 
           [0034]      FIG. 6  is a side view showing the power supplying plug lock device in the unlock state; 
           [0035]      FIG. 7  is a front view showing the power supplying plug lock device in a lock state; 
           [0036]      FIG. 8  is a side view showing the power supplying plug lock device in the lock state; 
           [0037]      FIG. 9A  is a perspective view showing the movement of a lock plate and two locking bars; 
           [0038]      FIG. 9B  is a perspective view showing the locking bar in a state incompletely fitted to the two locking bars; 
           [0039]      FIG. 9C  is a perspective view showing the locking bar in a state completely fitted to the two locking bars; 
           [0040]      FIG. 10A  is a schematic front view showing a link mechanism; 
           [0041]      FIG. 10B  is an enlarged plane view showing a top part of two links; 
           [0042]      FIG. 11A  is a front view showing the power supplying plug lock device during a lock operation (incompletely fitted state); 
           [0043]      FIG. 11B  is a front view showing the power supplying plug lock device during a lock operation (completely fitted state); and 
           [0044]      FIG. 12  is a side view showing a side view of the power supplying plug lock device during an unlocking operation. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0045]    One embodiment of a power supplying plug lock device for use with a hybrid vehicle (hereafter, referred to as the vehicle  1 ) will now be described with reference to  FIGS. 1 to 12 . 
         [0046]    Referring to  FIG. 1 , the vehicle  1  includes a hybrid system  4  that uses at least one of an engine  2  and a motor  3  to generate torque for driving vehicle wheels. A battery  5  is arranged in the hybrid system  4  as a power supply for the motor  3 . A charging system  6  that charges the battery  5  with an external power supply is applied to the vehicle  1 . The charging system  6  includes a power supplying plug  9 . The power supplying plug  9  is arranged on the distal end of a charging cable  8 , which is connected to a charging facility, such as a charging station or a household commercial power supply. The power supplying plug  9  is connected to the vehicle  1  to charge the battery  5 . 
         [0047]    As shown in  FIGS. 1 and 2 , a side wall of a vehicle body  10  includes a power receiving connector  11 , which is where the power supplying plug  9  is connected. A lid  12 , which is coupled to the vehicle body  10  by a hinge, opens and closes an accommodation compartment  13 , which accommodates the power receiving connector  11 . An inlet  14 , which includes electric connection terminals, such as a power terminal and a control terminal, is arranged in the power receiving connector  11 . A plug connection detection sensor  15  is arranged in the inlet  14  to detect that the power supplying plug  9  has been completely fitted to the inlet  14 . 
         [0048]    As shown in  FIGS. 2 and 3 , the power supplying plug  9  includes electric connection terminals, such as a power terminal and a control terminal, corresponding to the electric connection terminals of the power receiving connector  11 . The power supplying plug  9  includes a plug body  16 . A lock arm  17  is arranged on the plug body  16  to prevent removal of the power supplying plug  9  from the inlet  14 . A pivot shaft  18  is arranged in a longitudinally middle part of the lock arm  17 . The pivot shaft  18  is pivotal about the pivot shaft  18 . The lock arm  17  includes a distal end defining a hook  19  and a basal end defining an arm operation portion  20 . The hook  19  and the arm operation portion  20  are exposed from the plug body  16 . An urging member  21  is arranged on the lock arm  17  near the arm operation portion  20  to urge the lock arm  17  toward a closing side. The lock arm  17  is one example of an operation arm. 
         [0049]    To connect the power supplying plug  9  to the power receiving connector  11 , the power supplying plug  9  is fitted straight into the inlet  14  along a fitting direction (in  FIG. 3 , the minus Y direction). When the hook  19  comes into contact with a projection  22  of the inlet  14 , the lock arm  17  is guided along a sloped surface  22   a  and moved upward on the projection  22 . When the power supplying plug  9  is completely fitted to the inlet  14 , the urging force of the urging member  21  pivots the lock arm  17  toward the closing side and hooks the hook  19  to the projection  22 . This prevents removal of the power supplying plug  9  from the inlet  14 . 
         [0050]    When it is determined with the plug connection detection sensor  15  that the power supplying plug  9  has been completely fitted to the inlet  14 , the hybrid system  4  starts supplying power from the charging facility  7  via the power supplying plug  9  to charge the battery  5 . When it is determined that the battery  5  has been fully charged, the hybrid system  4  ends the charging of the battery  5 . To remove the power supplying plug  9  from the inlet  14  after the charging ends, the arm operation portion  20  is pushed to move the lock arm  17  toward an opening side and separate the hook  19  from the projection  22 . In this state, the power supplying plug  9  is pulled straight out of the inlet  14  and removed from the vehicle  1 . 
         [0051]    As shown in  FIGS. 2 and 3 , a power supplying plug lock device  23  is arranged on the power supplying plug  9  to prevent unauthorized removal of the power supplying plug  9  from the inlet  14 . That is, the power supplying plug lock device  23  locks and prohibits operation of the power supplying plug  9 . The power supplying plug lock device  23  is attached to the lock arm  17  of the power supplying plug  9  to lock the power supplying plug  9  to the inlet  14 . 
         [0052]    As shown in  FIGS. 4 to 8 , the power supplying plug lock device  23  includes a case  24 . The case  24  includes a bottom surface provided with a fitting hole  25 , into which the arm operation portion  20  of the lock arm  17  may be fitted. The arm operation portion  20  is fitted into the fitting hole  25  to attach the power supplying plug lock device  23  to the power supplying plug  9 . 
         [0053]    As shown in  FIGS. 5 to 8 , the case  24  includes a lock mechanism  26 , which restricts movement of the lock arm  17 . The lock mechanism  26  includes a dial cylinder  27 , which is used for authentication. The dial cylinder  27  includes dials  28 , which are arranged in a line along the longitudinal direction of the lock device  23  (in  FIG. 6 , the Y direction). The dials  28  are supported to be rotatable about a dial shaft  29 . Each dial  28  includes a dial coupling gear  30 , which includes a notch formed at a predetermined location that is in accordance with a combination number, or authentication number, of the dial cylinder  27 . The dial cylinder  27  is one example of an authentication member. 
         [0054]    The lock mechanism  26  includes two opposing restriction members  31 , which are engaged with the arm operation portion  20 . The restriction members  31  serves as latches and are linearly movable back and fourth in the lateral direction of the lock device  23  (in  FIG. 5 , the X direction). Each restriction member  31  includes an inner end surface that is exposed from the fitting hole  25 . As shown in  FIG. 7 , when the power supplying plug lock device  23  is attached to the arm operation portion  20 , the inner end surfaces of the two restriction members  31  are inserted into engagement holes  32 , which are formed in the two side surfaces of the arm operation portion  20 . Further, each restriction member  31  includes an outer end surface coupled to an urging member  33 , which urges the restriction member  31  inward into the case  24 , that is, toward the fitting hole  25 . As shown in  FIG. 9A , a stopper  34  projects from the outer end surface of each restriction member  31  to prevent removal of the restriction member  31  from the case  24 . 
         [0055]    As shown in  FIG. 5 , one corner in the lower surface of each restriction member  31  defines a guide surface  35 , which allows the restriction member  31  to smoothly move into the arm operation portion  20 . The guide surface  35  is formed by curving one corner in the lower surface of the restriction member  31 . Further, one corner in the upper surface of each restriction member  31  defines a separation prevention corner  36  that results in the restriction member  31  resisting removal from the engagement hole  32  of the arm operation portion  20 . That is, the separation prevention corner  36  prevents the restriction member  31  from easily separating from the arm operation portion  20 . The separation prevention corner  36  is formed by one corner on the upper surface formed having an angle of about 90 degrees. 
         [0056]    As shown in  FIGS. 5 and 9A , the lock mechanism  26  includes first and second locking bars  37  and  38 , which are linearly movable back and fourth in the lateral direction (X direction). The first and second locking bars  37  and  38  may support the corresponding restriction members  31  from the outer side. Further, the locking bars  37  and  38  are generally L-shaped and symmetric to each other in the lateral direction when viewed from the front. The first and second locking bars  37  and  38  are examples of a lock member. 
         [0057]    As shown in  FIGS. 9A to 9C , the first and second locking bars  37  and  38  include coupling pieces  37   a  and  38   a , respectively. The coupling piece  37   a  includes a rail portion  39  into which the coupling piece  38   a  is fitted. Thus, the first and second locking bars  37  and  38  are linearly moved toward and away from each other in the lateral direction (X direction) along the rail portion  39 . 
         [0058]    Further, the first and second locking bars  37  and  38  respectively include support pieces  37   b  and  38   b , which extend in the vertical direction of the lock device  23  (in  FIG. 9A , the Z direction). The support pieces  37   b  and  38   b  may support the corresponding restriction members  31  from the outer side. As shown in  FIG. 5 , an urging member  40  is arranged between the inner surface of the case  24  and the support piece  37   b  to urge the first locking bar  37  in the inward direction. In the same manner, an urging member  41  is arranged between the inner surface of the case  24  and the support piece  38   b  to urge the second locking bar  38  in the inward direction. 
         [0059]    When the restriction members  31  move away from each other in an opening direction (in  FIG. 9A , the direction of arrow K1), the first and second locking bars  37  and  38  are pushed by and moved integrally with the restriction members  31  in the opening direction. When force in the opening direction is not applied, the restriction members  31  are moved toward each other in a closing direction (in  FIG. 9A , the direction of arrow S1) by the urging force of the urging members  33 . In this case, the first and second locking bars  37  and  38  are also moved toward each other in the closing direction (in  FIG. 9A , the direction of arrow S1) by the urging force of the corresponding urging members  40  and  41 . 
         [0060]    As shown in  FIGS. 5 to 8 , the lock mechanism  26  includes a lock plate  42  that cooperates with the locking bars  37  and  38  to shift the lock mechanism  26  to a lock state. The lock plate  42  is arranged to be linearly movable back and fourth in the vertical direction (in  FIG. 5 , the Z direction). Two urging members  43  are arranged between the inner surface of the case  24  and the lock plate  42 . The lock plate  42  includes two restriction pieces  42   a  that may support the corresponding restriction members  31  from the outer side. As shown in  FIG. 7 , the urging force of the urging members  43  moves the lock plate  42  in a lock direction (in  FIG. 7 , the direction of arrow K2). When each restriction piece  42   a  is arranged at the outer side of the corresponding restriction member  31 , movement of the restriction member  31  in the opening direction is restricted. Accordingly, each restriction member  31  is held at a projected position (close position). The lock plate  42  is one example of a movable member. In this example, the locking bars  37  and  38 , the lock plate  42 , and the urging members  33 ,  40 ,  41 , and  43  form a position holding mechanism. 
         [0061]    As shown in  FIG. 5 , the lock plate  42  includes a main body portion  42   b , which serves as an upper piece that couples the two restriction pieces  42   a . The main body portion  42   b  includes an upper surface from which projections  44  project toward the dials  28 . The projections  44  are arranged in correspondence with the dials  28  so that one of the projections  44  corresponds with one of the dials  28 . The projections  44  are aligned along the dial shaft  29 . Each projection  44  may be engaged with a notch  45  formed in the dial coupling gear  30  of the corresponding dial  28 . When the dials  28  are arranged so that their combination of numbers is correct, the notches  45  are aligned along the dial shaft  29 . In this state, the projections  44  may enter the corresponding notches  45 . This permits vertical movement of the lock plate  42 . 
         [0062]    As shown in  FIGS. 5 and 6 , the main body portion  42   b  of the lock plate  42  includes a lower surface from which a plate-shaped projection  46  projects toward the locking bars  37  and  38 . As shown in  FIG. 9A , an upper surface of the coupling piece  37   a  in the first locking bar  37  includes a fitting groove  47 . The projection  46  may be fitted to the fitting groove  47  from above. In the same manner, an upper surface of the coupling piece  38   a  in the second locking bar  38  includes a fitting groove  48 , which is similar to the fitting groove  47 . As shown in  FIG. 9A , when the locking bars  37  and  38  move toward each other in the closing direction, the fitting grooves  47  and  48  are not in alignment. In this state, the projection  46  comes into contact with the upper surfaces of the coupling pieces  37   a  and  38   a  and is not fitted to the fitting grooves  47  and  48 . As shown in  FIGS. 9B and 9C , when the locking bars  37  and  38  move away from each other in the opening direction, the fitting grooves  47  and  48  are aligned with each other, and the projection  46  may be fitted into the fitting grooves  47  and  48 . In this state, the lock plate  42  holds the locking bars  37  and  38  at a retracted position and restricts movement of the restriction members  31  in the opening direction. 
         [0063]    As shown in  FIGS. 5 and 6 , when the projection  46  of the lock plate  42  is not fitted to the fitting grooves  47  and  48  of the locking bars  37  and  38 , movement of the restriction members  31  is permitted. In this case, the power supplying plug lock device  23  (lock mechanism  26 ) is in an unlock state. As shown in  FIGS. 7 and 8 , when the locking bars  37  and  38  move away from each other in the opening direction and the fitting grooves  47  and  48  are aligned with each other, the lock plate  42  is lowered by the urging force of the urging members  43  and the projection  46  enters the fitting grooves  47  and  48 . In this state, the restriction pieces  42   a  of the lock plate  42  are located at the outer side of the corresponding restriction member  31 . Thus, movement of each restriction member  31  in the opening direction is restricted by the lock plate  42 . In this case, the power supplying plug lock device  23  (lock mechanism  26 ) is in a lock state. 
         [0064]    As shown in  FIGS. 4 ,  6 , and  8 , the power supplying plug lock device  23  further includes an unlock portion  49  that is operated to release the lock mechanism  26  from a lock mechanism  26  and return the lock mechanism  26  to an unlock state. In this example, as the unlock portion  49 , two push type unlock buttons  50  are arranged on two side surfaces of the case  24  in the longitudinal direction of the lock device  23  (in  FIG. 6 , the Y direction). The unlock portion  49  is operated, for example, by holding the two unlock buttons  50  so that the index finger comes into contact with one of the unlock buttons  50  and the thumb comes into contact with the other one of the unlock buttons  50 . 
         [0065]    As shown in  FIGS. 6 and 8 , each unlock button  50  is coupled to the restriction members  31  by a link mechanism  51 . As shown in  FIG. 10A , each link mechanism  51  includes two link members  52  that intersect with each other. The link members  52  are pivotally coupled to the case  24  about a pivot shaft  53 , which is arranged at where the link members  52  intersect each other. An elongated hole  54  extends through a lower end of each link member  52 . A coupling projection  55  (refer to  FIG. 9A ), which is formed on the end surface of each restriction member  31 , is inserted into each elongated hole  54 . 
         [0066]    As shown in  FIG. 10B , an upper end of each link member  52  defines a pushing surface  56  that pushes the pushed unlock button  50  back to its original position. Each pushing surface  56  is formed by inwardly bending the upper end of the link member  52 . The two link members  52  are coupled to each other so that the opposing pushing surfaces  56  form a tapered ridge. The pushing surfaces  56  may be pushed by a pushing pin  57  that is formed on a lower portion of the corresponding unlock button  50 . 
         [0067]    As shown in  FIGS. 6 and 8 , the lock plate  42  has two end surfaces in the longitudinal direction (in  FIG. 6 , the Y direction) defining sloped surfaces  58  that are inclined downward. Each unlock button  50  includes a lifting portion  59  that may push the corresponding sloped surface  58 . The lifting portion  59  projects from the unlock button  50  above the pushing pin  57 . 
         [0068]    When the power supplying plug lock device  23  is in the lock state ( FIG. 8 ) and the two unlock buttons  50  are pushed, the pushing pins  57  push the pushing surfaces  56  of the corresponding link mechanism  51 . Thus, the link members  52  of each link mechanism  51  are pivoted in the opening direction (in  FIG. 10A , the direction of arrow S3). As a result, the restriction members  31  are moved away from each other in the opening direction (in  FIG. 9A , the direction of arrow K1). Further, the lifting portion  59  of each unlock button  50  pushes the corresponding sloped surface  58  of the lock plate  42 . This linearly moves the lock plate  42  upward, that is, in the unlock direction (in  FIG. 5 , the direction of arrow S2). 
         [0069]    The operation of the power supplying plug lock device  23  will now be described with reference to  FIGS. 5 to 12 . 
         [0070]    When the power supplying plug lock device  23  is not attached to the power supplying plug  9 , the power supplying plug lock device  23  is in an unlock state as shown in  FIGS. 5 and 6 . In this state, the dials  28  are arranged so that their combination of numbers is correct, and the notches  45  are aligned parallel to the dial shaft  29 . Thus, the projections  44  are all arranged in the notches  45 . The projection  46  of the lock plate  42  is arranged on the upper surface of the locking bars  37  and  38 , and the lock plate  42  is lifted in the unlock direction (in  FIG. 5 , the direction of arrow S2). That is, the lock plate  42  is held at the unlock position. 
         [0071]    When the lock plate  42  is located at the unlock position, each restriction piece  42   a  is separated from the outer rear side of the corresponding restriction member  31 . Accordingly, each restriction member  31  is not in a lock state. That is, the restriction members  31  are linearly movable away from each other in the opening direction (in  FIG. 9A , the direction of arrow K1). In this state, the lock plate  42  is urged in the lock direction (downward direction) by the urging members  43 . However, as shown in  FIG. 9A , the projection  46  is located above the coupling pieces  37   a  and  38   a  of the locking bars  37  and  38  and not fitted to the fitting grooves  47  and  48 . Thus, the lock plate  42  is held at an unlock position. 
         [0072]    To lock the power supplying plug  9  to the inlet  14 , the power supplying plug lock device  23  is attached to the arm operation portion  20  of the lock arm  17 . As shown in  FIG. 11A , when the arm operation portion  20  enters the fitting hole  25 , the restriction members  31  are pushed by the arm operation portion  20  and moved away from each other in the opening direction (in  FIG. 11A , the direction of arrow K1). In this state, the first and second locking bars  37  and  38  are also pushed by the restriction members  31  and moved away from each other in the opening direction. 
         [0073]    When the movement of the first and second locking bars  37  and  38  aligns the two fitting grooves  47  and  48 , the lock plate  42  becomes movable in the lock direction. Here, the lock plate  42  is moved in the lock direction by the urging force of the urging members  43 . However, as shown in  FIG. 11A , before the arm operation portion  20  is completely fitted into the fitting hole  25 , that is, when each restriction member  31  is located at an open position and not arranged in the corresponding engagement hole  32  of the arm operation portion  20 , the projection  46  of the lock plate  42  is not completely fitted to the fitting grooves  47  and  48 . In this state, each restriction piece  42   a  of the lock plate  42  comes into contact with the upper surface  31   a  of the corresponding restriction member  31 . This restricts movement of the lock plate  42  in the lock direction. Accordingly, the lock plate  42  cannot be lowered to the lowermost position. Thus, as shown in  FIGS. 9B and 11A , the lock plate  42  is in an incomplete fitting state in which the projection  46  is incompletely fitted to the fitting grooves  47  and  48 . 
         [0074]    In the incomplete fitting state, the locking bars  37  and  38  are held at the retracted positions. However, the lock plate  42  is arranged on the upper surfaces  31   a  of the restriction members  31  and thus does not reach the lock position. When the restriction members  31  move to the open position, the upper surfaces  31   a  of the restriction members  31  restrict movement of the lock plate  42  to the lock position. Thus, the upper surfaces  31   a  function as restriction surfaces that maintain the lock plate  42  in a state incompletely fitted to the locking bars  37  and  38 . Before the lock device  23  is attached to the power supplying plug  9 , the restriction surfaces (upper surfaces  31   a ) prevent the lock device  23  from inadvertently shifting to a lock state. For example, during the attachment of the lock device  23 , even when the user touches and slightly moves the restriction members  31 , the restriction surfaces (upper surfaces  31   a ) keep the lock plate  42  in an incompletely fitted state. This prevents the lock device  23  from being inadvertently shifted to a lock state. 
         [0075]    As shown in  FIG. 11B , when the arm operation portion  20  is further inserted into the fitting hole  25 , the restriction members  31  are moved in the closing direction by the corresponding urging members  33 . As shown in  FIG. 7 , when the restriction members  31  are completely fitted to the engagement holes  32  of the arm operation portion  20  and reach the close positions, the lock plate  42  is released from the restriction imposed by the upper surface  31   a  (restriction surface) of each restriction member  31 . Thus, the urging force of the urging members  43  moves the lock plate in the lock direction. As a result, as shown in  FIG. 9C , the lock plate  42  enters a completely fitted state in which the projection  46  is completely fitted to the fitting grooves  47  and  48 . 
         [0076]    As shown in  FIGS. 7 and 8 , in the completely fitted state, the restriction pieces  42   a  of the lock plate  42  are located at the outer side of the corresponding restriction members  31 . This restricts movement of the restriction members  31  in the opening direction. That is, the lock plate  42  is located at the lock position, and each restriction member  31  is held at a projected position (closing position). This maintains the lock device  23  in the lock state. Here, the projections  44  of the lock plate  42  are removed from the notches  45  thereby allowing for rotation of the dials  28 . Thus, the user may turn each dial  28  to obtain any combination of numbers and thereby hide the correct combination. If the combination of numbers of the dials  28  is not correct, the projections  44  of the lock plate  42  cannot enter the notches  45  even when the unlock buttons  50  are pushed. This prevents an unauthorized person from performing unlocking. 
         [0077]    When releasing the power supplying plug lock device  23  from the lock state, as shown in  FIG. 12 , the numbers of the dials  28  are set to the correct combination, and the two unlock buttons  50  are then simultaneously pushed. Here, the lifting portions  59  push the sloped surfaces  58  upward and move the lock plate  42  in the unlock direction (in  FIG. 12 , the direction of arrow S2). Accordingly, the restriction pieces  42   a  of the lock plate  42  move away from the outer side of the corresponding restriction members  31 . This releases the lock device  23  from the lock state. 
         [0078]    At the same time, the projection  46  of the lock plate  42  is removed from the fitting grooves  47  and  48 . Thus, the first and second locking bars  37  and  38  are moved in the closing direction (in  FIG. 9A , the direction of arrow S1) by the urging members  40  and  41  and returned to their original initial positions. As a result, the lock device  23  returns to an unlock state in which the projection  46  of the lock plate  42  is located on the coupling pieces  37   a  and  38   a.    
         [0079]    Further, when the two unlock buttons  50  are pushed, the pushing pins  57  push the two pushing surfaces  56  thereby pivoting the corresponding link mechanism  51  in the open direction (in  FIG. 10A , the direction of arrow S3). As a result, the restriction members  31  move away from each other in the opening direction (in  FIG. 9A , the direction of arrow K1). This separates the restriction members  31  from the engagement holes  32  of the arm operation portion  20 . Thus, the power supplying plug lock device  23  may be removed from the arm operation portion  20 . In this state, the power supplying plug lock device  23  may be removed from the arm operation portion  20  by pushing the two unlock buttons  50 . 
         [0080]    In the present embodiment, the power supplying plug  9  may be locked to the inlet  14  just by attaching the power supplying plug lock device  23  to the arm operation portion  20  of the lock arm  17 . This facilitates the locking of the power supplying plug  9 . Further, the power supplying plug  9  is locked with the power supplying plug lock device  23 , which is a dedicated lock. Thus, only the authorized user who possesses the lock device  23  may lock the power supplying plug  9 . This prevents an unauthorized person from locking the power supplying plug  9 . 
         [0081]    The power supplying plug lock device  23  of the present embodiment has the advantages described below. 
         [0000]    (1) The power supplying plug  9  may be locked to the inlet  14  just by attaching the power supplying plug lock device  23  to the arm operation portion  20  of the lock arm  17 . This allows the power supplying plug  9  to be locked to the inlet  14  just by performing a simple task of setting the power supplying plug lock device  23  onto the arm operation portion  20 . Further, the power supplying plug lock device  23  of the present example, or the dedicated lock device, is required to lock the power supplying plug  9 . Thus, the power supplying plug  9  may be locked with a widely used padlock or the like. This prevents an unauthorized person from locking the power supplying plug  9  in an unauthorized manner.
 
(2) The power supplying plug lock device  23  does not enter the lock state unless the two restriction members  31  are simultaneously pushed in the open direction. Thus, even if one of the two restriction members  31  is inadvertently pushed, the power supplying plug lock device does not enter the lock state. This prevents inadvertent switching to the lock state.
 
(3) The lock plate  42 , the two locking bars  37  and  38 , and the urging members  33 ,  40 ,  41 , and  34  are used to hold the restriction members  31  in the lock state. Thus, the power supplying plug  9  may be locked to the inlet  14  with a simple structure using these components.
 
(4) The power supplying plug lock device  23  includes the unlock portion  49 . Operation of the unlock portion  49  switches the power supplying plug lock device  23  from the lock state to the unlock state. Thus, the power supplying plug lock device  23  may easily be removed from the lock arm  17 .
 
(5) The guide surface  35  is arranged on the lower surface of each restriction member  31 . Thus, when attaching the power supplying plug lock device  23  to the arm operation portion  20 , the guide surface  35  guides movement of the restriction member  31  in the opening direction. This allows for smooth attachment of the power supplying plug lock device  23  to the arm operation portion  20 .
 
         [0082]    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 scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms. 
         [0083]    The power supplying plug lock device  23  is not limited to a structure that is engaged with the engagement holes  32  of the arm operation portion  20 . For example, the arm operation portion  20  may include a protrusion that forms a step, and the power supplying plug lock device  23  may be engaged with the step. 
         [0084]    The authentication member is not limited to the dial cylinder  27  and may be, for example, a key cylinder. Alternatively, the authentication member may perform electronic authentication. 
         [0085]    Although only the lower surface of each restriction member  31  is curved in the above embodiment, the upper surface and the lower surface of the restriction member  31  may both be curved. 
         [0086]    The restriction members  31 , the urging members  33 , the lock members (locking bars  37  and  38 ), the urging members  40  and  41 , and the urging members  43  do not necessarily have to be arranged in pairs. For example, just one of the two restriction members  31  may be engaged with the arm operation portion  20 . In this case, the other parts related with the restriction member  31  may also be provided as a single component. More specifically, just one of the two urging members  33 , just one of the locking bars  37  and  38 , just one of the urging members  40  and  41 , and just one of the urging members  43  need be used. 
         [0087]    The operation arm is not limited to the lock arm  17 , which includes a pivot shaft arranged in a longitudinally middle portion. For example, the lock arm  17  may have a pivot shaft arranged at one of its longitudinal ends. 
         [0088]    In the above embodiment, the position holding mechanism uses the lock plate  42  and the two locking bars  37  and  38 . The shapes of the lock plate  42  and locking bars  37  and  38  may be changed as required. Further, the number and location of the urging members used for the position holding mechanism may be changed as required. 
         [0089]    The unlock buttons  50  do not have to be arranged as a pair. For example, there may be just one unlock button  50 . 
         [0090]    The unlock portion  49  is not limited to the two unlock buttons  50  and may have another structure. For example, the unlock portion  49  may be of an electric drive type. 
         [0091]    The urging members  33 ,  40 ,  41 , and  43  are not limited to springs and may be changed to other members. 
         [0092]    The vehicle  1  is not limited to a hybrid vehicle and may be an electric vehicle driven by just a motor. 
         [0093]    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.