Abstract:
A breaker apparatus comprises: a breaker switch including a pair of fixed electrodes standing upright on the breaker body, a plug detachably mounted on the breaker body, and a movable electrode provided on the plug for disconnecting and connecting between both fixed electrodes by being pulled out or pushed in to the both fixed electrodes; and a fuse mounted in parallel with the breaker switch, characterized in that a locking lever is pivotably mounted on one of the breaker body and the plug and the locking lever is pivoted to the locking position where the plug is locked in the fitted state, in that the breaker body is provided with a micro switch having a swinging strip for detecting whether or not the locking lever is pivoted to the locking position so that the micro switch is activated when the tip of the locking lever pivots along the length of the swinging strip and presses the swinging strip on the way to activate the micro switch, and in that the tip of the locking lever is formed so that the length is maximum at the rear edge that trails when the locking lever is pivoted toward the locking position and decreases gradually toward the leading edge.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a breaker apparatus to be used for switching the power cable connected to the battery or the like of the automotive vehicle between the conduction state and the out-of-conduction state.  
           [0002]    A breaker apparatus as disclosed in the Unexamined Japanese Patent Application Publication No. Hei 9-223439 is conventionally known as a breaker apparatus of the type described above. This breaker apparatus comprises, as shown in FIG. 14, a breaker switch including a pair of fixed electrodes  5 ,  5  standing upright on the breaker body  1  and a movable electrode  4  formed on the plug  3  to be fitted to the breaker body for plugging in and out of both fixed electrodes  5 ,  5 , and a fuse  2  provided in series with the breaker switch.  
           [0003]    When the plug  3  is pulled out, both fixed electrodes are disconnected so that the fuse  2  can be replaced with the cable e being in the out-of-conduction state, and thereafter when the fuse  2  is replaced and the plug  3  is fitted to the breaker body  1 , the movable electrode  4  connects between both fixed electrodes  5 ,  5  so as to bring the cable e into conduction.  
           [0004]    In this stage, it is important to know whether or not the plug  3  is properly fitted, and thus in the related art, a magnet  8  is provided at the prescribed position on the handle  7  to be used for fitting in or pulling out the plug  3  so that when the handle  7  is tilted down after the plug  3  is inserted, a magnet force of the magnet  8  is detected by the sensor (not shown) provided on the breaker body  1 , thereby detecting whether or not the plug  3  is correctly fitted. However, detection by a magnetic force is not sufficiently accurate since it may be affected by electrical current or the like around the sensor.  
           [0005]    In the conventional breaker apparatus, there is an apprehension that the plug  3  is held only by a frictional force between the movable electrode  4  and the fixed electrodes  5 ,  5  thereby being poor in retaining force, an apparatus providing a locking mechanism for positively retaining the plug at the fitted position is on the way to development. More specifically, the lock lever is pivotably provided on the plug, and when the lock lever is pivoted into the locking position after the plug is fitted in position, the plug is locked in the retained state together with the lock lever by the locking portion formed on the breaker body.  
           [0006]    Whether or not the lock lever is pivoted to the normal locking position is detected by the micro switch, whereby whether or not the plug is correctly fitted can be detected.  
           [0007]    An example of the structure described above is schematically shown in FIG. 15. In other words, the lock lever r is supported so as to be able to pivot from the upright position r 1  with respect to the plug to the horizontal locking position r 2 , and when the lock lever r is pivoted into the locking position r 2  after it is correctly fitted to the breaker body, the locking end r a  is locked to the locking portion of the breaker body.  
           [0008]    On the other hand, the breaker body is provided with a micro switch M in the pivoting area of the detecting end r b  of the lock lever r. The micro switch M is known switch having a swinging strip K as an actuator, wherein the swinging strip K is mounted vertically upwardly.  
           [0009]    When the lock lever r is pivoted to the locking position r 2 , the detecting end r b  presses the swinging strip K to turn the micro switch ON, and thereby detecting whether or not the lock lever is locked and the plug is correctly fitted, in which accuracy can be expected in comparison with the case using a magnetic force.  
           [0010]    The micro switch M described above is turned on when the button or the like is pressed by the movement of the swinging strip K from the natural state by a prescribed angle, and it is preferable that the micro switch M is turned on simultaneously with the arrival of the lock lever r at the locking position r 2 . However, when considering tolerances of the mounting position of the micros witch M or the locking lever r, a time lag occurs between the timing when the swinging strip K presses the detecting end r b  of the locking lever r and the timing when the micro switch is turned on.  
           [0011]    Especially, in FIG. 15, when the micro switch M and the lock lever r are positioned at a distance from each other, it is set so that the micro switch M is turned on slightly before the lock lever r reaches the locking position r 2  because the condition that the micro switch M is not turned on even in the state where the lock lever r is in the locked state must be avoided.  
           [0012]    Therefore, employing a locking lever r having a same width along the whole length thereof allows a timing of pressing the micro switch M to be earlier, and thus not some little process is required until the lock lever r is locked after the micro switch M is turned on. However, there may be cases where the lock lever r is not locked completely because its pivotal movement is interrupted on the way although the micro switch M is turned on and a signal indicating that the locking is complete is obtained, whereby detection of the completion of locking cannot be performed correctly.  
           [0013]    As a matter of course, there are some considerable countermeasures such as reducing the width of the lock lever, or changing the mounting position of the locking lever or the micro switch to shift the timing of pressing the swinging strip of the micro switch. However, the former has a limit in the strength, and the latter cannot be employed easily since major design changes are required.  
           [0014]    With such conditions in view, an object of the present invention is to provide a system in which detection of the completion of locking can be made correctly while minimizing design changes involved.  
         SUMMARY OF THE INVENTION  
         [0015]    In order to achieve the object described above, the first aspect of the present invention is a breaker apparatus comprising: a breaker body, a breaker switch including a pair of fixed electrodes standing upright on the breaker body, a plug detachably mounted on the breaker body, and a movable electrode provided on the plug for disconnecting and connecting between both fixed electrodes by being pulled out or pushed in to the both fixed electrodes; and a fuse mounted in parallel with the breaker switch, characterized in that a locking lever is pivotably mounted on one of the breaker body and the plug and the locking lever is pivoted to the locking position where the plug is locked in the fitted state, in that the breaker body is provided with a micro switch having a swinging strip for detecting whether or not the locking lever is pivoted to the locking position so that the micro switch is activated when the tip of the locking lever pivots along the length of the swinging strip and presses the swinging strip on the way to activate the micro switch, and in that the tip of the locking lever is formed so that the length is maximum at the rear edge that trails when the locking lever is pivoted toward the locking position and decreases gradually toward the leading edge.  
           [0016]    The second aspect of the present invention is a breaker apparatus as set forth in the first aspect, characterized in that the locking lever is provided on the plug for serving also as a handle.  
           [0017]    &lt;First Aspect of the Invention&gt;  
           [0018]    When a plug is mounted on the breaker apparatus, both fixed electrodes are brought into conduction via the movable electrode in the plug. When the locking lever is pivoted to the locking position after the plug is correctly fitted, the plug is locked in a retained state. In association with the pivotal movement of the locking lever into a locking position, the tip of the locking lever abuts against the swinging strip and presses the same, and thus the micro switch is activated.  
           [0019]    Since the shape of the tip of the locking lever is such that the length is maximum at the rear edge that trails when the locking lever is pivoted to the locking position and reduces gradually toward the leading edge, it presses the swinging strip when it moves closer to the locking position than the case of the conventional case to activate the micro switch.  
           [0020]    Referring now to FIG. 11, the effect of the invention will be described while comparing with the conventional apparatus employing a locking lever having a same width along the whole length thereof.  
           [0021]    In the same figure, the sign R designates the locking lever of the present invention, and the sign r designates the conventional locking lever, and the micro switch M is turned on when the swinging strip K is pressed by the tip of the locking lever R, r and swung by a prescribed angle from the natural state to the position G. The signs S and s designate centerlines of the width of the locking lever of the present invention and of the conventional locking lever respectively passing through the axis of the pivotal movement thereof, and locking action is completed when the centerlines S and s reach the position C (locking position) . At this time, the swinging strip K reaches the position H.  
           [0022]    When the locking levers R, r and the micro switch M is disposed at the shortest distance with respect to each other within a tolerance, for example, the conventional locking lever r activates the micro switch M when it reaches the position A. On the other hand, since the tip portion of the locking lever R of the present invention is shaped in such a manner that the trailing edge is the longest and the leading edge forms so called a clearance, the trailing edge of the tip portion presses the swinging strip K by a prescribed angle when the centerline reaches the position B to activate the micro switch.  
           [0023]    In other words, according to the present invention, the micro switch M can be activated later than the case of the conventional case by the time period corresponding to the angle between A and B, i.e. at the timing when it is closer to the locking position C than the conventional case. In other words, the difference between the activation of the micro switch M and the arrival of the locking lever R to the locking position C may be reduced so that the completion of locking can be detected correctly.  
           [0024]    In addition, it requires only minor design changes such as changing the shape of the tip portion of the locking lever R.  
           [0025]    &lt;Second Aspect of the Invention&gt;  
           [0026]    Since fitting locking of the plug can be performed in a series of actions in the state of gripping the locking lever, the workability is improved.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a perspective view of a breaker apparatus according to the first embodiment of the present invention;  
         [0028]    [0028]FIG. 2 is a perspective view of the breaker apparatus showing a state in which the cover and the plug are removed;  
         [0029]    [0029]FIG. 3 is a perspective view showing a state in which the plug is inserted into the plug storage section;  
         [0030]    [0030]FIG. 4 is a cross sectional side view of the breaker body;  
         [0031]    [0031]FIG. 5 is a plan view of the breaker body;  
         [0032]    [0032]FIG. 6 is a perspective view showing the projecting wall and fixed electrodes;  
         [0033]    [0033]FIG. 7 is a cross sectional side view showing a state prior to fitting the plug on the projecting wall;  
         [0034]    [0034]FIG. 8 is a cross sectional side view showing a state in which the plug is fitted on the projecting wall;  
         [0035]    [0035]FIG. 9 is a cross sectional view of the breaker apparatus;  
         [0036]    [0036]FIG. 10 is an enlarged view showing a process in which the activating portion abuts against the detecting strip;  
         [0037]    [0037]FIG. 11 is an enlarged view showing a state in which the activating portion plug is abutted against the detecting strip;  
         [0038]    [0038]FIG. 12 is an enlarged view showing a part of an activating section according to another embodiment;  
         [0039]    [0039]FIG. 13 is a schematic comparative drawing of the present invention and the conventional apparatus;  
         [0040]    [0040]FIG. 14 is a perspective view of a conventional breaker; and  
         [0041]    [0041]FIG. 15 is a schematic drawing showing a process in which the bar shaped locking lever abuts against the detecting strip.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]    Referring now to FIG. 1 to FIG. 10, an embodiment of the present invention will be described. The breaker apparatus of this embodiment is provided at some midpoint of the power cable of the electric vehicle for switching the power cable between the conduction state and the out-of-conduction state.  
         [0043]    The breaker body  10  provided in this breaker apparatus is, as shown in FIG. 1, provided with a pair of elongated walls  13 ,  13  along the length of the plate-shaped base  11 , and the ends of these elongated walls  13 ,  13  are connected by a short wall  14  on one side leaving the other ends open. The opened side is enlarged in a stepped manner so that a plug storage section  15  is formed therein, and the closed side is provided with a fuse storage section  16  enclosed by both elongated walls  13 ,  13  and the short wall  14 . The plug storage section  15  and the fuse storage section  16  are divided by the partitioning walls  17 ,  17  extending from both elongated walls  13 ,  13  toward each other.  
         [0044]    In the plug storage section  15  at the position away from the partitioning walls  17 , as shown in FIG. 4, a projecting wall  18  is standing upright from the base  11 , and the front and back surfaces facing in the direction along the length (toward left and right in FIG. 4) of the breaker body  10  are provided with a first and second fixed electrodes  20 ,  21 .  
         [0045]    Specifically, the front surface  18 A of the projecting wall  18  facing toward the right in FIG. 4 is provided with a first fixed electrode  20 , and the first fixed electrode  20  is formed by bending a metallic plate into L-shape so as to have a barrel portion  20 A on its proximal end, to which a power cable D 1  is crimped. The tip contact portion  20 B of the first fixed electrode on the opposite end from the barrel portion  20 A is inserted into the plug storage section  15  through a through hole  22  from the back side of the base  11  and laid on the proximal end of the front surface  18 A of the projecting wall  18 . On the tip side of the front surface  18 A of the projecting wall  18 , there is formed with a projecting portion  23  and the tip of the first fixed electrode  20  abuts against the lower surface of the projecting portion  23 .  
         [0046]    On the other hand, the back surface  18 B of the projecting wall  18  facing toward the left in FIG. 4 is provided with the second fixed electrode  21 , which is formed by bending a metallic plate into U-shape, and bending again one of the legs of the U-shape outwardly to form a right angle and providing a bolthole  21 A on the tip thereon. The second fixed electrode  21  is pressed into between the partitioning wall  17  and the projecting wall  18  from the bottom side of the U-shape so that the tip contact portion  21 B is laid on the proximal end of the back surface  18 B of the projecting wall  18 . Through the bolthole  21 A, a bolt B 1  provided on the fuse storage section  16  described later is passed.  
         [0047]    On the tip of the back surface  18 B of the projecting wall  18 , as shown in FIG. 6, a pair of rances  25 ,  25  for preventing the second fixed electrode  21  from being disengaged. These rances  25 ,  25  extend from the tip of the projecting wall  18  horizontally and then downwardly in parallel with the projecting wall  18 , and the tip of second fixed electrode  21  abuts against the lower surface of the engaging portion  25 A formed at the lower end portion (See FIG. 4). On the back surface  18 B of the projecting surface on both sides of the rances  25 , as shown in FIG. 6, a rance protecting walls  26 ,  26  standing upwardly beyond the rances  25  are provided.  
         [0048]    In the plug storage section  15  at the position away from the projecting wall  18  farther than the partitioning walls  17 , there is formed an end wall  27  standing upright from the base  11 , as shown in FIG. 1, and the plug  50  described later is guided by the end wall  27  and fitted to the tip of the projecting wall  18 .  
         [0049]    The back side of the base  11  corresponding to the plug storage section  15  (the surface facing downward in FIG. 4) is provided with a cable holding portion  24  for holding the cable D 1  extending from the first fixed electrode  20 . The cable holding portion  24  receives, as shown in FIG. 5, a cable D 1  between a pair of opposed walls  24 A,  24 A suspended from the back surface of the base  11  facing with respect to each other, and limits the downward movement of the cable D 1  by means of a pair of cable engaging projections  24 B,  24 B projecting from the opposed walls  24 A,  24 A toward each other. The cable engaging projection  24 B is formed with a guiding surface inclining downwardly for providing ease of the cable D 1  passage as far as it will go.  
         [0050]    The fuse storage section  16  will now be described. As shown in FIG. 4, the fuse storage section  16  is provided on both shorter ends with a pair of seat portions  16 C,  16 C protruding from the base  11 , in which metallic bolts B 1 , B 2  are insert molded with their heads embedded and the threaded portion extended upward. The second fixed electrode  21  is inserted into the bolt B 1  located near the plug storage section  15 , and the terminal strip  32  is inserted into the other bolt B 2 .  
         [0051]    The terminal strip  32  is formed by bending a metallic plate into a crank shape and provided with a cable D 2  on the barrel portion  32 A formed on one end thereof. Then, the bolt B 2  is inserted into the bolthole  32 B formed on the tip of the terminal strip  32  with the cable D 2  inserted into the fuse storage section  16  through the service hole  33  (See FIG. 4) from the back side of the base  11 . The cable D 2  is pulled outwardly from the service hole  33  and held by the cable holding portion  34  provided on the back side of the base  11 .  
         [0052]    As shown in FIG. 4, the cable holding portion  34  comprises a pair of opposing walls  34 A,  34 A suspended from both edge of the service hole  33  on the back surface of the base  11  and connected between the lower edges thereof by a bottom wall  34 B, so that most part of the service hole  33  is covered. The cable D 2  is prevented from being drooped downwardly by an elongated projection  34 C projecting upward from the bottom wall  34 B.  
         [0053]    The fuse  35  stored in the fuse storage section  16  comprises, as shown in FIG. 1, a metallic projections  35 A,  35 A projecting from both ends of the cylindrical body and having respectively round holes  35 B passing therethrough, through which both bolts B 1 , B 2  of the fuse storage section  16  are inserted and tightened with nuts N, N thereon.  
         [0054]    The fuse storage section  16  is fitted with a cover  40  shown in FIG. 2. The cover  40  comprises an elongated top wall  41  formed corresponding to the fuse storage section  16 , a pair of elongated walls  43 ,  43  extending in parallel along the length thereof, and a short wall  44  connecting the ends of these elongated walls  43 ,  43  with the other ends left open. On the opened end, the rectangular vertical wall  45  is suspended from the top wall  41  and is formed with a limiting projection  46  overhanging outwardly longitudinally of the cover  40  from the tip thereof.  
         [0055]    The plug  50  will be described. The plug  50  comprises, as shown in FIG. 2, a prism shaped housing  54  having a bottom on one end and an opening recess  51  (See FIG. 7) on the bottom side. The recess  51  is enlarged inside in comparison with the opening so that the movable electrode  70  can be accommodated.  
         [0056]    The movable electrode  70  is, as shown in FIG. 7, formed of a first and a second clamping strips  71 ,  72  to be brought into contact with the respective fixed electrodes  20 ,  21  connected by the connecting portion  73 . More specifically, the first clamping strip  71  is linearly extending along the inner surface of the recess  51  of the housing  54 , and the connecting portion  73  extends at a right angle from the proximal end (upper end in FIG. 7) of the first clamping strip  71 , then gently curved as it neared the second clamping strip  72 , and then continued to the second clamping strip  72 . On the tips of both clamping strips  71 ,  82 , there are provided contact points  71 A,  72 A projecting therefrom toward each other.  
         [0057]    The housing  54  is, as shown in FIG. 7, provided with a wall portion  54 A constituting a part of surrounding wall separately from the remaining main portion  54 B, and when the wall portion  54 A is not mounted on the main portion  54 B, the movable electrode  70  is stored into the recess  51  from the opening and then the opening is closed by the wall portion  54 A later. The movable electrode  70  stored in the recessed portion  51  abuts its lower end against the opening edge of the recess  51  so as not to be disengaged in the natural state.  
         [0058]    On the outer surface of the housing  54  of the plug  50 , a gate shaped locking lever  60  is pivotably mounted. The locking lever  60  is, as shown in FIG. 2, formed of a pair of arms  61 ,  61  connected on each end by the operating portion  62 , and each arm  61 ,  61  is provided with a pivot  63 ,  63  (See FIG. 7) projecting toward the housing  54 . The pivots  63 ,  63  are inserted into the axis hole  63 H (See FIG. 7) formed on both side surfaces of the housing  54 , so that the locking lever  60  is pivotable.  
         [0059]    On both side surfaces of the housing  54 , there are provided a rotational movement limiting projections  55 ,  56  for limiting the pivotable range of the locking lever  60 , whereby the locking lever  60  is pivotable in the range of 90 degrees between the upright position and the horizontal position.  
         [0060]    The locking lever  60  in the horizontal position locks the plug  50  together with the locking position  60  by engaging with the breaker body  10  so as not to be disengaged. The position of the locking lever  60  in this state is called as “a locking position”. In this locking position, the locking lever  60  engages with the engaging portions  64  provided on both arms  61 ,  61  respectively.  
         [0061]    The engaging portion  64  comprises a recess on the outer surface at approximately the center between the operating portion  62  of the arm  61  and the pivot  63 , and a elongated projection  64 A extending in the center of the recess along the length. Corresponding to each engaging portion  64 ,  64 , in the plug storage section  15  at the position away from the partitioning walls  17  farther than the end wall  27 , the engaging strips  28 ,  28  are standing adjacent to both elongated walls  13 ,  13 . In the engaging portion  64 , the elongated projection  64 A is engageable with the engaging projection  28 A provided on the upper end of the engaging strip  28   
         [0062]    The locking lever  60  is formed on each arm  61 ,  61  with an inserting portion  65  extending the rotating end opposite from the operating portion. When the locking lever  60  is rotated to the locking position, each inserting portion  65 ,  65  enters into the receiving section  29 ,  29  formed at the stepped portion of the elongated walls  13 ,  13  at the boundary between the plug storage section  15  and the fuse storage section  16 . These receiving sections  29 ,  29  are opened toward the direction along the length of the breaker body  10  and closed on the top portions thereof.  
         [0063]    One of these receiving sections  29 ,  29  (the nearer to the viewer in FIG. 1) is in communication with the micro switch fitting chamber  30 .  
         [0064]    The micro switch  31  is provided for controlling the electricity supplied to the breaker, and comprises a switching circuit (not shown) therein and a swinging strip  31 A on the back side thereof for opening and closing the switching circuit by pressing the button  31 B. The swinging strip  31 A is in the shape of a rectangular tongue extending vertically, the lower end of which is attached to the micro switch  31  in a swinging manner. The micro switch  31  fitted and fixed in the fitting chamber  30  is held with the upper end of the swinging strip  31 A inclined toward the plug storage section  15 , and in this state, the switch is “OFF” in which the switching circuit is opened. When the swinging strip  31 A is pressed by the activating portion  80  provided at the tip of the locking lever  60  and thus the button  31 B is pressed as described later, the micro switch  31  is turned “ON” in which the switching circuit is closed to activate and a signal indicating that locking is complete is supplied.  
         [0065]    This embodiment is constructed in such a manner that the button  31 B starts to be pressed almost simultaneously with the timing when the swinging strip  31 A is pressed.  
         [0066]    The activating portion  80  is formed on the tip of the inserting portion  65  shown in FIG. 2 so as to extend the arm  61  of the locking lever  60  longitudinally. The activating portion  80  is, as shown in FIG. 10, the longest at the rear edge that trails when the locking lever  60  is pivoted toward the locking position and becoming shorter toward the leading edge. The longest portion serves as an abutting portion  81  and the shorter portion serves as a clearance surface  82 .  
         [0067]    The abutting portion  81  has an round and smooth upper surface so as to press the swinging strip  31 A to switch the micro switch  31  between ON and OFF.  
         [0068]    On the other hand, the clearance surface  82  is formed by cutting from the abutting portion  81  toward the leading edge, more specifically, it is formed in a bevel inclining from the front end of the abutting portion  81  to the front end of the operating portion so as to approach the pivot  63  gradually. Therefore, when the abutting portion  81  abuts the swinging strip  31 A, the clearance surface  82  avoids contact with the swinging strip  31 A.  
         [0069]    The breaker apparatus of this embodiment has a structure as described above. The operation thereof will now be described. The breaker apparatus is mounted to the electric vehicle in a following manner. As a first step, a part of the power cables of the electric vehicle denoted as D 1  and D 2  above are attached, then the bolt is passed through the mounting hole  11 A (See FIG. 5) formed on the base portion  11 , and the breaker body  10  is fixed on a prescribed position of the electric vehicle.  
         [0070]    Then, the cover  40  is fitted to the fuse storage section  16  of the breaker body  10 . When the elongated wall  43  and the short wall  44  are pressed so as to fit around the elongated wall  13  and the short wall  14  of the breaker body  10 , and when it is pressed deeper, the engaging hole  44 A formed on the short wall  44  of the cover  40  and the engaging projection  14 A formed on the short wall  14  of the breaker body  10  are engaged with respect to each other (See FIG. 3). At this time, the vertical wall  45  formed on the cover  40  is inserted between a pair of partitioning walls  17 ,  17  formed on one end of the fuse storage section  16 , and the limiting projection  46  is laid in the vicinity of the proximal portion of the projecting wall  18  of the base  11  of the breaker body  10  (See FIG. 7).  
         [0071]    In this state, the locking bar  60  is gripped and the plug  50  is inserted deep in the plug storage section  15  provided on the breaker body  10  as shown in FIG. 3. In this case, only a single plug  50  is required to be mounted, mounting operation can be carried out very easy.  
         [0072]    When the plug  50  is mounted, the limiting projection  46  provided on the cover  40  is engaged with the lower surface  50 K of the plug  50  (See FIG. 8). Therefore, the cover  40  is engaged at both ends in locked state by this engagement with the plug  50  (engagement between the lower surface  50 K and the limiting projection  46 ) and the engagement described above with the breaker body  10  and (engagement between the engaging projection  14 A and the engaging hole  44 A), whereby the cover  40  is prevented from being disengaged due to inclination thereof.  
         [0073]    When the plug  50  has inserted deeply inside, the locking lever  60  is pivoted from the upright position to the horizontal position, as shown in FIG. 9. Then, in association with this pivotal movement, both inserting portions  65 ,  65 , of the locking lever  60  are inserted into the corresponding receiving section  29 ,  29 . Simultaneously, the activating portion  80  provided on one of the inserting portions  65  is inserted into the fitting chamber  30 .  
         [0074]    At this time, the activating portion  80  moves from the proximal end of the swinging strip  31 A of the micro switch  31  as the locking lever pivots.  
         [0075]    As shown in a dotted line in FIG. 10, since a clearance surface  82  is formed on the activating portion  80 , the activating portion  80  of this embodiment does not abut the swinging strip  31 A even when it reaches the position at which the operating portion of the conventional starts to press the swinging strip  31 A at the point X and thus to press the button  31 B.  
         [0076]    When the locking lever  60  is further pivoted and approaches the locking position, the activating portion  80  for the first time press the swinging strip  31 A by the abutting portion  81  at the trailing edge and starts to press the button  31 B (See FIG. 11). Even in this state, the activating portion  80  abuts against the swinging strip  31 A only at the abutting portion  81  without allowing the clearance surface  82  on the side of the leading edge to come into contact with the swinging strip  31 A. Therefore, the locking lever  60  turns the micro switch  31  on slightly before it reaches the locking position.  
         [0077]    Then immediately after the micro switch  31  is turned on, the locking lever  60  reaches the locking position and the engaging portion  64  and the engaging strip  28  are engaged with respect to each other, so that the plug  50  is retained in the plug storing section  15  so as not to be disengaged.  
         [0078]    When the plug is mounted in this way, in the plug  50 , the projecting wall  18  is interposed between the first clamping strip  71  and the second clamping strip  72  of the movable electrode  70 , and each clamping strip  71 ,  72  is brought into contact with each fixed electrode  20 ,  21  laid on the projecting wall  18 , whereby both fixed electrodes  20 ,  21  are brought in conduction so that the fuse  35  is fed with a current, as shown in FIG. 8. Simultaneously, the micro switch  31  which is turned on by the swinging strip  31 A being pressed transmits a signal indicating that the plug is mounted to a prescribed electrical circuit. Then a current flows across the fuse  35  via the cables D 1  and D 2  that is connected in conduction.  
         [0079]    When replacing the fuse  35 , the following steps are taken. As a first step, the plug  50  is pulled out from the plug storage section. Then the cover  40  is removed from the breaker body  10 . Since the upper surface of the fuse storage section  16  is opened, the nut N fixing the fuse  35  is removed and replaced with a new fuse  35 . When the operator tried to remove the cover  40  with the plug  50  mounted, the limiting projection  46  prevents the removal of the cover  40 . In other words, unless the plug  50  is completely removed and the fuse  35  is completely brought out of conduction, the cover cannot be removed from the breaker body  10 , so that replacement of the fuse can be curried out safely.  
         [0080]    After the fuse  35  is replaced, by mounting the cover  40  and the plug  50 , and operating the locking lever  60  as in the procedure described above, the breaker apparatus is fed with a current.  
         [0081]    As is described thus far, the breaker apparatus according to this embodiment, since the operating portion comprises an abutting portion  81  on its edge that trails when the locking lever is pivoted toward the locking position, and a clearance surface  82  toward the leading edge, the activating portion  80  presses the swinging strip  31 A at the position closer to the locking position than the case of the conventional apparatus and turns the micro switch  31  on. Therefore, the time lag between the moment when the micro switch  31  is turned on and the moment when the lock lever  60  reaches the locking position may be reduced and thus the completion of locking can be detected more precisely.  
         [0082]    In addition, it requires only minor design changes such as changing the configuration of the activating portion  80 .  
         [0083]    According to the present invention, the operator may carry out a series of steps from fitting of the plug  50  to locking of the same with the lock lever  60  kept gripped and without changing the grip. When replacing the fuse, releasing of the lock and disengagement of the plug  50  can be made with the lock lever  60  kept gripped, thereby improving workability.  
         [0084]    &lt;Other Embodiment&gt;  
         [0085]    The present invention is not limited to the embodiment described above, and for example, following embodiments are also included within the technical field of the invention. In addition, various modifications other than the following embodiments may be made without departing from the scope of the invention.  
         [0086]    (1) Though the clearance surface  82  in the embodiments described above is formed in a bevel, the clearance surface  82  A may be in the form of a curved surface as shown in FIG. 12.  
         [0087]    (2) In the embodiment described above, though the activating portion  80  is formed by extending the rotating end of the arm  61  of the locking lever  60  opposite from the operating portion  62 , the operating portion may be formed in a cranked shape by bending the rotating end of the arm  61  opposite from the operating portion  62  rearward.  
         [0088]    (3) In the embodiment described above, though the activating portion  80  is formed on the tip of the inserting portion  65 , there may be provided an activating portion on the operating portion  62  of the locking lever and a micro switch is disposed correspondingly.  
         [0089]    (4) In the embodiment described above, though the locking lever  60  is provided on the plug  50 , it is also possible to provide a locking lever on the breaker body  10  and engages with the plug at the locking position.