Power plug locking device having a control unit for moving a lock member between different positions

When a power plug locking device moves a plate to a lock position or unlock position, the plate is rotated toward an operational end position with a power plug lock motor while the current of the motor is detected. When the plate comes into contact with a switching piece of a switching mechanism, the switching piece applies a load to the plate. When the current flowing through the motor becomes greater than or equal to a threshold, the supply of power to the power plug lock motor is stopped. Then, switching load of the switching mechanism 48 pushes and moves the disk to an operational end position (lock position or unlock position).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2011-073127, filed on Mar. 29, 2011, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a power plug locking device that locks a power plug to an object, such as a vehicle, and prevents unauthorized removal of the power plug from the object.

Over these recent years, consumers have become conscious of environmental problems. Thus, vehicles that emit less carbon dioxide such as hybrid vehicles and electric vehicles have become popular. Such vehicles are driven by a battery-powered motor. When such a vehicle travels over a long distance and the state of charge of the battery becomes low, the battery must be charged (refer to Japanese Laid-Open Patent Publication No. 9-161898).

The charging of a battery involves an electrolytic reaction of compounds and ions in battery cells of the battery. This lengthens the charging time. Thus, when a user leaves the vehicle while the battery is being charged, someone may remove the power plug to steal electricity. Hence, locking devices have been developed to prevent unauthorized removal of the power plug from a vehicle.

Such a power plug locking device may include a pivotal hook-shaped lock arm and a movable lock bar. The lock arm is arranged on the power plug and prevents separation of the power plug from the inlet. The lock bar restricts movement of the lock arm. When the lock arm is hooked to a projection of the inlet, the lock bar is moved to above the lock arm to restrict movement of the lock arm. In this state, the lock bar locks the power plug to the inlet. From this state, by moving the lock bar away from the lock arm, the power plug becomes unlocked.

When the lock bar is electrically driven by a motor or the like, the lock bar may be actuated through current detection control. Referring toFIG. 8, current detection control, for example, measures the current flowing through the motor (load current value), estimates the motor rotation speed (load rotation speed) from the measured current value, and calculates the moved distance of the lock bar from the motor rotation speed. When the current continuously exceeds a threshold and the moved distance of the lock bar has reached a minimum required distance, the lock bar is determined as being located at a normal position and that overcurrent is flowing through the motor. Thus, the supply of power to the motor is stopped. The execution of such current detection control eliminates the need for sensors and allows for the power plug locking device to be reduced in size.

The calculation of the load rotation speed from the load current value uses a non-load rotation speed and non-load current value. The parameters use values taken under a condition in which the rotation of the motor is the slowest (e.g., ambient temperature of 85 degrees Celsius). This prevents erroneous determination of the lock bar being in a lock state when it is actually not in such a state.

However, under a condition in which the rotation of the motor is the fastest (e.g., ambient temperature of −40 degrees Celsius), the difference between the actual state and the calculated state becomes large. As shown inFIG. 9, repetition of locking and unlocking operations accumulates such differences. This results in the lock bar being determined through calculations as having reached its end position even though it has actually not reached such position. In such a case, the user may erroneously be notified that the lock bar has reached the end position.

SUMMARY OF THE INVENTION

One aspect of the present invention is a power plug locking device that prevents unauthorized removal of a power plug from an inlet. The power plug locking device includes a lock member arranged in the inlet. The lock member blocks removal of the power plug when the power plug is connected to the inlet. A drive unit moves the lock member. A control unit controls the drive unit to move the lock member from an operational start position to an operational end position. The control unit obtains positional information of the lock member. A movable mechanism mechanically moves the lock member from a usable position, which is a position before the operational end portion, to the operational end position. The control unit controls the drive unit based on the positional information to move the lock member to the usable position. The control unit stops the drive unit when the lock member reaches the usable position. The movable mechanism mechanically moves the lock member from the usable position to the operation end position.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of a power plug locking device according to the present invention will now be described with reference toFIGS. 1 to 7.

Referring toFIG. 1, a hybrid vehicle1includes an engine2and a motor3arranged in a vehicle body10. The engine2and the motor3form a hybrid system4and generate power to rotate vehicle wheels. The hybrid system4includes a battery5, which serves as a power source for the motor3. The vehicle1also includes a charge system6that charges the battery5with an external power supply. The charge system6uses a charging facility7, such as a charging station or a residential power outlet. The charging facility7provides a charge cable8and a power plug9, which is arranged on a distal end of the charge cable8. The power plug9is connected to the vehicle1to charge the battery5.

Referring toFIGS. 1 and 2, the vehicle body10includes a lid12, which opens and closes an accommodation compartment13. A power reception connector11arranged in a side wall of the vehicle body10is arranged in the accommodation compartment13. The power plug9is connected to the power reception connector11. The power reception connector11includes an inlet14including electric connection terminals (e.g., power terminal and control terminals).

Referring toFIGS. 2 and 3, the power plug9is arranged in the power supply side of the charge system6and includes electric connection terminals connected to the electric connection terminals of the inlet14. The power plug9includes a plug body15and a lock arm16. The lock arm16is pivotally coupled to the plug body15to prevent separation of the power plug9from the inlet14. A pivot shaft17pivotally supports a longitudinally middle part of the lock arm16. The lock arm16includes a distal portion defining a hook18and a basal portion defining a lever19. The hook18and lever19are exposed from the plug body15. An urging member20is arranged near the lever19to constantly urge and force the lock arm16in a closing direction.

To connect the power plug9to the power reception connector11, the power plug9is fitted straight in an insertion direction (−Y axis direction ofFIG. 3) into the power reception connector11. This guides and raises the hook18along a sloped surface21aof a projection21on the inlet14. When the plug9is completely fitted to the inlet14, the urging force of the urging member20pivots the lock arm16and hooks the hook18to the projection21. This prevents separation of the power plug9from the inlet14. When determining that the power plug9has been completely fitted to the inlet14, the hybrid system4charges the battery5with the power plug9(charging facility7).

To remove the power plug9from the inlet14after charging is completed, the lever19is pushed to pivot the lock arm16away from the projection21in an opening direction. In this state, the power plug9is pulled straight out of the inlet14and removed from the vehicle1.

Referring toFIGS. 4 and 5, the power reception connector11includes a power plug locking device22, which prevents unauthorized removal of the power plug9from the inlet14. The power plug locking device22includes a case23and a lock mechanism24, which is arranged in the case23. The lock mechanism24functions as a mechanical part of the power plug locking device22. The lock mechanism24of the present example is electrically actuated by a motor until a locking or unlocking operation is performed for a certain extent and then mechanically actuated by a switching load of a mechanical component.

The case23includes a lock body25, which forms a main part of the case23, and a lid26, which closes an opening of the lock body25. The case23accommodates a power plug lock motor27, which functions as a drive source for the power plug locking device22. The power plug lock motor27, which may be a DC motor, is arranged so that its motor shaft28is arranged in a lateral direction (Y axis direction inFIG. 4) of the power plug locking device22. The power plug lock motor27corresponds to a drive unit.

The motor shaft28is coupled to a worm gear mechanism29, which is rotated by the power plug lock motor27. The worm gear mechanism29includes a worm gear30, which is arranged on the motor shaft28, and a helical gear31, which is meshed with the worm gear30. The worm gear mechanism29is provided with a function that prevents the helical gear31from rotating the worm gear30. That is, the worm gear mechanism29is provided with a self-lock function.

Two positioning tabs32and33, which determine the rotational position of the helical gear31, project from the circumferential wall of the helical gear31. The lock side positioning tab32is used to position the helical gear31at a lock position, and the unlock side positioning tab33is used to position the helical gear31at an unlock position. Referring toFIG. 5, the positioning tabs32and33come into contact with a stopper34, which is arranged in the case23.

A generally plate-shaped link35is coupled to the helical gear31and supported to be pivotal about an axis La. The link35is overlapped with the helical gear31so that the axis La extends through the link35. An engagement projection36extends from an edge of the link35in the Z axis direction ofFIG. 4. The engagement projection36is engaged with an engagement recess37in a circumferential wall of the link35. When the helical gear31is rotated, the engagement projection36comes into contact with either one of inner walls37aand37bof the engagement recess37. This integrally rotates the link35with the helical gear31. The link35is rotatable relative to the helical gear31for an amount corresponding to the length W of the engagement recess37. The link35and the engagement recess37form a movable mechanism.

A triangular plate38is coupled to the link35to restrict movement of the lock arm16. The plate38is pivoted in synchronism with the link35. A pivot shaft39extends from a basal portion of the plate38in the Z axis direction ofFIG. 4. The distal end of the pivot shaft39includes a D-shaped engagement portion40. A D-shaped engagement hole41extends through the central part of the link35. The engagement portion40of the pivot shaft39is engaged with the engagement hole41of the link35. A snap ring42prevents separation of the link35from the plate38. The plate38forms a lock member. The link35, the plate38, and the helical gear31are rotatable about the same axis.

A locking lever43, which restricts the position of the lock arm16in cooperation with the plate38, is coupled to the case23. The locking lever43is pivotal about an axis Lb of a shaft44. The locking lever43has a lower portion defining a triangular arm contact portion45, which contacts the hook18of the lock arm16. The arm contact portion45is exposed from an opening46formed in the bottom surface of the case23. When the power plug9is connected to the inlet14, the arm contact portion45contacts the lock arm16. An urging member47, which constantly urges the locking lever43toward the lock arm16, is arranged on the shaft44.

During a locking operation, the lock mechanism24of the present example pushes the engagement projection36of the link35with the inner wall37aof the helical gear31as the power plug lock motor27produces rotation in one direction. As a result, the lock mechanism24pivots the link35and the plate38in a locking direction (the direction of arrow K1inFIG. 4) and moves the link35and the plate38to an intermediate locking portion. During an unlocking operation, the lock mechanism24of the present example pushes the engagement projection36of the link35with the inner wall37bof the helical gear31as the power plug lock motor27produces rotation in the other direction. As a result, the lock mechanism24pivots the link35and the plate38in an unlocking direction (the direction of arrow S1inFIG. 4) and moves the link35and the plate38to an intermediate unlocking portion.

The case23accommodates a switching mechanism48. When the link35and the plate38reach the lock or unlock intermediate position, the switching mechanism48then mechanically rotates the link35and the plate38to an end position, namely, a lock position or unlock position. The switching mechanism48includes a switching piece49, which pushes the link35in the rotating direction, and an urging member50, which constantly urges the switching piece49toward the link35. The switching piece49is generally T-shaped when viewed from above and includes a curved distal end. The urging member50is formed by, for example, a coil spring. The switching mechanism48forms a movable mechanism.

When the link35is rotated from the unlock position to the lock position or from the lock position to the unlock position, a curved pushing portion51of the rotated link35pushes the switching piece49in the direction of arrow K2inFIG. 4against the urging force of the urging member50. This accumulates force in the urging member50. As the pushing portion51starts to move off the switching piece49, the urging force of the urging member50forces the switching piece49toward the link35in the direction of arrow S2inFIG. 4. Then, the switching piece49pushes the pushing portion51and rotates the link35and the plate38toward the lock position.

When the plate38reaches the lock position and is arranged above the locking lever43, upward pivoting of the locking lever43is restricted. Here, the power plug locking device22is in a lock state. When the plate38reaches an unlock position and is separated from the locking lever43, upward pivoting of the locking lever43is permitted. Here, the power plug locking device22is in an unlock state.

Referring toFIG. 1, the power plug locking device22includes a plug lock control unit52that controls the locking and unlocking operation of the power plug locking device22. The plug lock control unit52is formed by, for example, an integrated circuit (IC). The plug lock control unit52controls the power plug lock motor27and rotates the plate38to switch the power plug locking device22between the lock and unlock states. The plug lock control unit52.

The plug lock control unit52detects the current of the power plug lock motor27to perform a locking or unlocking operation. The plug lock control unit52measures the current flowing through the power plug lock motor27, estimates the motor rotation speed from the measured current value, and calculates the moved distance of the plate38(link35) from the motor rotation speed (estimated value). When the current continuously exceeds a threshold and the moved distance of the plate38has reached a minimum required distance, the plug lock control unit52determines that the plate38is located at a normal position and that overcurrent is flowing through the power plug lock motor27. Thus, the plug lock control unit52stops the supply of current, or power, to the power plug lock motor27. When the current continuously exceeds the threshold but the moved distance of the plate38has not reached the minimum required distance, the plug lock control unit52determines that the plate38is located at an abnormal position and that overcurrent is flowing through the power plug lock motor27. Thus, after a certain time elapses, the plug lock control unit52stops the supply of power to the power plug lock motor27. The motor rotation speed corresponds to an actuation amount.

In the present example, during locking and unlocking operations, the link35moves over the switching piece49. This applies a load on the power plug lock motor27and increases the load flowing to the power plug lock motor27. At this point of time, the plug lock control unit52determines that the value of the current flowing through the power plug lock motor27has become greater than or equal to the threshold and stops supplying current to the power plug lock motor27. The link35and the plate38are subsequently rotated by the switching load of the switching mechanism48to move the plate38to the lock position or unlock position.

The operation of the power plug locking device22will now be described with reference toFIG. 5. When the power plug locking device22is in the unlock state shown inFIG. 5Aand the plug lock control unit52receives a lock trigger, the plug lock control unit52controls the power plug lock motor27to produce rotation in one direction (e.g., forward direction) and start the locking operation. This rotates the helical gear31in the locking direction (the direction of arrow K1inFIG. 5A) and then pushes the inner wall37aof the helical gear31with the engagement projection36of the link35. As a result, the helical gear31, the link35, and the plate38rotate integrally in the locking direction. Further, the pushing portion51of the link35pushes the switching piece49and inwardly moves the switching piece49straight in the direction of arrow K2inFIG. 5A.

Referring toFIG. 5B, during the locking operation, when the link35moves over or moves off the switching piece49, the load applied to the power plug lock motor27becomes the largest. This increases the current flowing through the power plug lock motor27. Thus, the plug lock control unit52determines that the current has become greater than or equal to the threshold and stops supplying power to the power plug lock motor27. Inertial force then continues to rotate the link35.

Referring toFIG. 5C, when the link35moves off the switching piece49, the lock side positioning tab32comes into contact with the stopper34and prevents further rotation of the helical gear31. At this point of time, the helical cannot be further rotated in the locking direction, and only the link35and the plate38can be further rotated in the locking direction.

As the link35moves off the switching piece49, the urging force of the urging member50pushes the link35. As a result, the switching piece49moves outwardly and linearly in the direction of arrow K2inFIG. 5C. In this manner, after the supply of power to the power plug lock motor27is stopped in accordance with the detected current, the switching load of the switching mechanism48continues to rotate the link35and the plate38to the lock position. Here, the link35and the plate38are rotated in the locking direction by an amount corresponding to the length W of the engagement recess37.

Referring toFIG. 5D, when the engagement projection36of the link35comes into contact with the inner wall37bof the engagement recess37in the helical gear31, the rotation of the link35and the plate38is stopped. In this state, the plate38is arranged above the locking lever43and thereby restricts pivoting of the locking lever43. As a result, movement of the lock arm16, which is hooked to the projection21in the inlet14, in the opening direction is limited. Thus, the power plug locking device22is in a lock state, and the power plug9is fixed to the inlet14.

Referring toFIG. 6, when connecting the power plug9to the inlet14, the hook18may not be correctly hooked to the projection21. For example, the hook18may become stuck and not be completely hooked to the projection21. Such a state is referred to as an incomplete hooking state. Under such a situation, the lock arm16would be held above the locking lever43. Thus, the locking lever43would be in the movement path of the plate38. As a result, when the plate38rotates in the locking direction, the plate38would hit the locking lever43. This would stop the rotation of the plate38before reaching the lock position.

In such a case, the lock arm16may be moved in upward, downward, leftward, and rightward directions to lower the hook18to the normal position. Then, the locking lever43is pivoted downward by the urging force of the urging member47. Subsequently, the switching load restarts the rotation of the link35and the plate38in the locking direction to the lock position. In this manner, even when incomplete hooking occurs, adjustment of the lock arm16would allow the switching mechanism48to rotate the plate38to the normal lock position. Unlocking operations are basically performed under the same principle as locking operations and thus will not be described.

Referring toFIG. 7, in the present example, the plate38is rotated while the plug lock control unit52detects the current of the power plug lock motor27. After the plug lock control unit52stops the power plug lock motor27in accordance with the detected current, the switching load of the switching mechanism48moves the plate38to its end position, which is the lock position or unlock position. Thus, in an incomplete hooking state, the timing at which the plate38would hit the locking lever43is later than the timing at which the current detection stops the rotation of the plate38with the power plug lock motor27. This allows for adjustment of the lock arm16before the plate38hits the locking lever43.

After the detected current stops the rotation of the plate38with the power plug lock motor27, the plate38is forcibly moved to its end position. As a result, a position obtained by the plug lock control unit52(i.e., operational end determination position) conforms to the actual position of the plate38. This avoids errors in the position of the plate38obtained by the plug lock control unit52and the actual position. Thus, even when locking and unlocking operations are repeated, errors are not accumulated. This prevents erroneous determination of the position of the plate38.

Further, even when the plate38is incompletely hooked to the lock arm16, the position of the lock arm16can be adjusted to resolve the incomplete hooking. Then, the switching load of the switching mechanism48would move the plate38to the lock position. This would prevent a state in which the power plug locking device22cannot shift to the lock state even though a locking operation is being performed.

The present embodiment has the advantages described below.

(1) The current flowing to the power plug lock motor27is detected to move the plate38to a location before the operational end position (lock position or unlock position). From this position to the operational end position, the switching load of the switching mechanism48mechanically moves the plate38. This conforms, or initializes, the position of the plate38obtained by the plug lock control unit52with the actual position. Thus, errors do not occur between the calculated position and the actual position.

(2) Even when the lock arm16is in an incomplete hooking state, as soon as the incomplete hooking state is resolved, the switching load of the switching mechanism48moves the plate38to the lock position. This ensures that the locking operation is performed.

(3) The power plug lock motor27only needs to move the plate38to an intermediate position. This shortens the time during which the power plug lock motor27is supplied with power and thereby reduces power consumption.

When moving the plate38to the intermediate position, the current detection does not necessarily have to be performed. For example, a timer may be used so that the plate38is moved to a predetermined position by supplying a motor with power until a certain time elapses.

A motor operational trigger (lock trigger or unlock trigger), when cooperating with the door lock of a vehicle, may be a current or voltage supplied to a door lock motor or a switch signal output when a dedicated operation member is supplied.

The lock member does not have to be of a rotational type and may be of a linear type that moves straight.

The lock mechanism24is not limited to the structure of the above embodiment and may be modified. For example, the plate38may directly restrict movement of the lock arm16in the opening direction.

The lock mechanism24may be such that it shifts to a lock state when the locking lever43is fitted into a receptacle of the power plug9.

The driving means is not limited to a motor and may be, for example, a solenoid.

The movable mechanism is not limited to the switching mechanism48and may be a different mechanical mechanism.

The concept of the present example may be applied to just either one of the locking side and unlocking side.

The vehicle1is not limited to a hybrid vehicle and may be, for example, an electric vehicle driven by only a motor.

The power plug locking device22is not limited to the vehicle1and may be applied to other devices or apparatuses.