Abstract:
In order to form a locking mechanism for a switch-on button of a circuit breaker which has a simple and inexpensive configuration, the locking mechanism has a locking element which is mounted rotatably on the switch-on button. The locking element, held directly in a first position by a first spring, enables actuation of the switch-on button and, directly in the switched-on state of the circuit breaker by a second spring, can be moved into a second position. The switch-on button of the circuit breaker is locked to prevent actuation in the second position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a locking mechanism for a switch-on button of a circuit breaker. 
     A locking mechanism for a switch-on button of a circuit breaker is known from DE 10 2005 038 629. The therein disclosed locking mechanism for the switch-on button of the circuit breaker comprises a force transmission element for transmitting the force exerted on the switch-on button at switch-on to a tripping mechanism, which force transmission element is swiveled away in the case of a switched-on circuit breaker so that the switch-on button cannot initiate re-actuation. 
     2. Brief Summary of the Invention 
     The object of the present invention is to implement a locking mechanism of simple and inexpensive design for a switch-on button of a circuit breaker. 
     This object is achieved according to the invention by a locking mechanism for a switch-on button of a circuit breaker, which locking mechanism has a locking element rotatably mounted on the switch-on button, which locking element, retained in a first position directly by a first spring, allows the switch-on button to be actuated and, in the switched-on state of the circuit breaker, can be moved directly by a second spring to a second position, wherein in the second position the switch-on button of the circuit breaker is locked against actuation. 
     Such an implementation of a locking mechanism for the switch-on button of a circuit breaker has a simple and inexpensive design because, due to the rotatable mounting of the locking element on the switch-on button and the direct positioning in a first or second position, as the case may be, by a first or second spring, only a small number of components are used to implement effective locking of a switch-on button and therefore reliably prevent re-actuation of the switch-on button in the case of an already switched-on circuit breaker. In other words, with such a locking mechanism a so-called reclosure interlock is implemented whereby, with the circuit breaker already ON and the closing spring of the stored-energy spring mechanism re-loaded, re-actuation of the switch-on button is prevented. 
     In an advantageous embodiment of the invention, the first spring engages with the switch-on button and the locking element. 
     In another advantageous embodiment of the invention the second spring engages with the locking section and a switch shaft lever of the circuit breaker. 
     In another advantageous embodiment of the invention, a locking bolt of the locking element engages in a locking recess of a support plate of the circuit breaker in the second position of the locking element. 
     Such arrangements of a first spring and second spring and of a locking bolt on the locking element, said locking bolt engaging in a locking recess of the support plate of the circuit breaker, provide a simple means of implementing an effective reclosure interlock for a circuit breaker of this kind, wherein a force exerted by the second spring in the second position of the locking element is greater than a force exerted by the first spring on the locking element in the second position as long as the circuit breaker is in its ON state, so that during this state the locking or more specifically the reclosure interlock is reliably maintained. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The invention will now be explained in greater detail on the basis of the drawing and an exemplary embodiment with reference to the accompanying figures, in which: 
         FIG. 1  shows a three-dimensional view of a locking mechanism according to the invention prior to assembly; 
         FIG. 2  shows a side view of a switch-on button of the locking mechanism from  FIG. 1 ; 
         FIG. 3  shows a plan view of the switch-on button from  FIG. 2 ; 
         FIG. 4  shows the assembled locking mechanism in a first state of the circuit breaker; 
         FIG. 5  shows a side view of the locking mechanism in the state of  FIG. 4 ; and 
         FIG. 6  shows the locking mechanism in a second, locked state with the circuit breaker ON. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a locking mechanism  1  for a switch-on button  2  of a circuit breaker (not depicted in further detail), wherein the switch-on button  2  is designed to close the circuit breaker, which circuit breaker has, for example, a stored-energy spring mechanism comprising a closing spring. With circuit breakers of this kind, the closing spring is re-loaded after a switch-on operation in order to be ready for a subsequent switching operation. In this state, with the circuit breaker ON and the closing spring already re-loaded, re-actuation of the switch-on button and therefore open-circuiting is reliably prevented. The switch-on button  2  in this described state of the circuit breaker must be locked against re-switching by means of the locking mechanism  1 . The switch-on button  2  has an actuator  3  with which an operator can actuate the switch-on button to switch the circuit breaker on. The switch-on button  2  additionally has two guide bars  4  and  5  having an actuation end  6 , wherein the guide bars  4  and  5  are disposed around a support plate  7  of the circuit breaker and the actuation end  6  is designed to actuate a mechanism for releasing the closing spring and switching on the circuit breaker (not depicted in greater detail here). For this purpose the support plate  7  has a first recess  8  and a second recess  9 . The second recess  9  is designed to accommodate a compression spring  10  and latching means of the switch-on button  2 , wherein the latching means are provided as an end stop of the switch-on button  2  at a first stop  11  of the second recess  9  and the compression spring  10  is designed to return the switch-on button  2  to its original position following execution of a switching operation. The support plate  7  additionally has fastening means  12  for fixing to a base plate of the circuit breaker. In the first recess  8 , a locking recess  13  is provided which interacts with a locking element  14  rotatably mounted on the switch-on button, said locking element  14  being rotatably mounted on a bearing  15  in a recess  16  of the switch-on button and having a locking bolt  17  which, in a second position of the locking element  14 , engages in the locking recess  13  of the support plate  7 , wherein, in the second position of the locking element  14 , the circuit breaker is in its ON state with the closing spring already re-loaded. For this purpose the locking element  14  is held pre-loaded in a first position on the switch-on button  2  by means of a first spring  18 , said first spring being fastened to a first dome  19  of the switch-on button and to a second dome  20  of the locking element and pre-loaded such that the locking element is in the first position shown in  FIG. 1  in which the locking bolt, when actuated, cannot engage in the locking recess  13 . A second spring  21  is fastened to a third dome of the locking element  14  and switch shaft lever (not visible in  FIG. 1 ), said second spring  21 , in the first position of  FIG. 1 , having a low loading such that a force of the second spring  21  is less than a force exerted by the first spring  18  on the locking element  14 . 
       FIG. 2  shows a side view of the switch-on button  2  with its actuator  3 , its actuation end  6  and the locking element  14  in its first position, said locking element being held in this position via the first spring  18  as long as the circuit breaker is in its switched-off state and the second spring  21  is unloaded. 
       FIG. 3  shows a plan view of the switch-on button  2  with its actuator  3  and the guide bars  4  and  5  as well as the bearing  15  and the locking bolt  17 , wherein rotatable mounting of the locking element  14  with respect to the switch-on button is implemented by the bearing  15 . Also shown in  FIG. 3  is the compression spring  10  and latching lugs  23  and  24  which, as already explained in greater detail with reference to  FIG. 1 , are provided in the second recess  9  as a stop and latching arrangement. 
       FIG. 4  shows the locking mechanism  1  in its assembled state, wherein the second spring  21  is attached to a switch shaft lever  25  in a mounting opening  26 , which switch shaft lever  25  is non-rotatably fixed to a switch shaft recess  27  on a circuit breaker switch shaft (not shown) so that when a drive movement is initiated from a stored-energy spring mechanism and the switch shaft rotates, the switch shaft lever  25  rotates with the switch shaft during execution of a switch-on operation.  FIG. 4  shows the locking element  14  in its first position in which the first spring  18  is loaded such that force exerted by the first spring  18  on the locking element  14  is greater than the force exerted by the second spring  21  on the locking element  14 , so that the locking element  14  is oriented parallel to the guide bars  4  and  5  of the switch-on button  2  and in particular the locking bolt  17  does not project above the guide bars  4  and  5 . 
       FIG. 5  shows a side view of the locking mechanism  1  in the same state as in  FIG. 4  with the locking element and switch on button  2  or more specifically guide bars  4  and  5  oriented parallel to one another and with a force exerted by the first spring that is greater than the force exerted by the second spring in the state of the first position. 
       FIG. 6  shows another side view of the locking mechanism  1  after execution of a switching operation or more specifically actuation of the actuator  3  of the switch-on button  2  by an operator, wherein after execution of the switching operation of the circuit breaker by rotation of the switch shaft, the switch shaft lever  25  has likewise rotated and, as a result of rotation of the switch shaft lever  25 , the second spring  21  is placed in its loaded state, the spring constant of the second spring  21  being selected such that, in said loaded state, the force of the second spring on the locking element  14  is greater than the spring force of the first spring  18  which, as a result of said rotation of the switch shaft lever  25  and the corresponding rotation of the locking element  14  around the bearing  15 , is likewise further loaded and therefore exerts on the locking element  14  a corresponding restoring force which is however less than the force exerted by the second spring  21  on the locking element  14 . When the locking element  14  rotates around the bearing  15  and the switch-on button  2  is returned by the compression spring  10  following execution of a switch-on operation, the locking bolt  17  engages in the locking recess  13  of the support plate  7  from  FIG. 1  as long as the second spring  21  is loaded, so that re-actuation of the switch-on button  2  is effectively prevented by the locking of the locking bolt  17  in the locking recess  13  and opening of the circuit breaker is therefore likewise effectively prevented. Only after a switch-off operation of the circuit breaker, which involves rotation of the switch shaft and corresponding rotation of the switch shaft lever  25 , is the second spring  21  unloaded, so that the restoring force exerted by the first spring  18  to return the locking element  14  from the second position shown in  FIG. 6  to the first position shown in  FIG. 5  is made possible and re-actuation of the switch-on button and switch-on of the circuit breaker is re-enabled. 
     LIST OF REFERENCE CHARACTERS 
     
         
           1  locking mechanism 
           2  switch-on button 
           3  actuator 
           4 ,  5  guide bars 
           6  actuation end 
           7  support plate 
           8  first recess 
           9  second recess 
           10  compression spring 
           11  stop 
           12  fastening means 
           13  locking recess 
           14  locking element 
           15  bearing 
           16  recess 
           17  locking bolt 
           18  first spring 
           19  first dome 
           20  second dome 
           21  second spring 
           22  third dome 
           23 ,  24  latching lugs 
           25  switch shaft lever 
           26  mounting opening 
           27  switch shaft recess