Patent Publication Number: US-7902472-B2

Title: Arrangement, in particular, for activating a transport pawl and clamping device for a spring energy store of an electric switch comprising such an arrangement

Description:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/EP2007/050793 which has an International filing date of Jan. 26, 2007, which designated the United States of America and which claims priority on German application No. 10 2006 006 907.2 filed Feb. 9, 2006, the entire contents of each of which are hereby incorporated herein by reference. 
     FIELD 
     At least one embodiment of the invention generally relates to an arrangement. In at least one particular example embodiment, it relates to an arrangement for actuating a transport pawl with a movable actuating device, which is held on a supporting framework and, in a first actuation phase, can be moved over out of a rest position into an end position counter to the force of a restoring spring and, in a second actuation phase, can be moved over out of the end position back into the rest position under the force of the restoring spring. 
     At least one embodiment of the invention furthermore generally relates to a tensioning apparatus for a spring-energy store of an electrical switch with such an arrangement. 
     BACKGROUND 
     An arrangement is known, for example, from the document EP 0 756 749 B1. In this known arrangement for a circuit breaker, a tension lever is provided as the actuating device, on which tension lever a transport pawl is articulated. The transport pawl is used for stepwise rotation of a ratchet wheel arranged fixedly on a tensioning shaft. An additional cutout is provided in one of the teeth of the ratchet wheel. This additional cutout ensures that, given a predetermined tensioning excursion of the tension lever, the tensioning shaft cannot be rotated back by an angle corresponding to the full pitch of the teeth of the ratchet wheel if the tensioning excursion is not completely performed by the manual lever. As a result, the tensioning shaft is held in a position in which a switching mechanism already effectively latches a tensioned spring-energy store of the circuit breaker. 
     It is known from the document DE 101 20 783 C1 that a display element can be coupled to such a switching mechanism for a spring-energy store. This coupling can take place in such a way that, as early as shortly before the effective latching of the tensioned spring-energy store, it is indicated that the spring-energy store is completely tensioned. In this case, there is the risk that, in the case of an incompletely performed tensioning excursion, the display element indicates a completely tensioned spring-energy store and therefore switch-on readiness, but the circuit breaker cannot yet be switched on. 
     SUMMARY 
     At least one embodiment of the invention includes an arrangement configured in such a way that the operator of the actuating device is made aware of incomplete actuation of the actuating device. 
     In accordance with at least one embodiment of the invention, an inhibiting mechanism, blocks the actuating device in the direction of its rest position during the first actuation phase when a first intermediate position is reached and releases it again when a second intermediate position is reached. 
     An example configuration of at least one embodiment of the invention provides that a guide face of the actuating device and a pawl lever are used as the inhibiting mechanism,
         the guide face having a recessed first section and a projecting second section,   the pawl lever being capable of pivoting about a stationary pivot spindle and being supported on a dead-center spring, and   the pawl lever having an arm, which, during the first actuation phase, engages in the movement path of the recessed section when the first intermediate position of the actuating device is reached, which arm, having been pivoted out of the movement path of the recessed section beyond the dead-center point of the dead-center spring by sliding on the projecting section when the second intermediate position of the actuating device is reached, is supported on a first stop, and which arm, having been pivoted again beyond the dead-center point of the dead-center spring by sliding on a second stop at the end of the second actuation phase, is supported in resilient fashion on the guide face.       

     In a further example embodiment configuration it is provided that the actuating device is a tension lever, which is capable of pivoting about a stationary pivot bearing. 
     The novel arrangement of at least one embodiment can be used in particular in tensioning apparatuses for spring-energy stores of electrical switches which have a tensioning shaft and a manual drive for rotating the tensioning shaft and in which the manual drive has a ratchet wheel, which is arranged fixedly on the tensioning shaft, and a transport pawl, which is prestressed in resilient fashion against the ratchet wheel for the purpose of rotating the ratchet wheel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the present invention will now be explained in more detail with reference to the attached drawings, in which: 
         FIG. 1  shows a low-voltage circuit breaker with a drive mechanism, which has a tensioning shaft for tensioning a spring-energy store, 
         FIG. 2  shows a detail of the low-voltage circuit breaker with an arrangement for actuating a transport pawl, which is arranged fixedly on the tensioning shaft, 
         FIG. 3  shows a sectional illustration of the low-voltage circuit breaker with a movable contact, which is coupled to the spring-energy store, and with a stationary contact, and 
         FIGS. 4 to 11  show the arrangement for actuating the transport pawl shown in  FIG. 2  in various phases of its movement sequence. 
     
    
    
     DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS 
     The low-voltage circuit breaker  1  shown in  FIG. 1  has a housing which comprises two half shells  2 ,  3  and is used for accommodating a contact arrangement, as is described in more detail in  FIG. 3 . Furthermore, the low-voltage circuit breaker  1  has a plurality of arc-quenching chambers  4  and a drive mechanism  6 , which is supported on a supporting framework  5  and can be covered by a covering hood (not illustrated) to be fastened on the front half shell  2  of the housing. 
     The supporting framework  5 , which comprises a plurality of supporting plates  7 ,  8  and is likewise fastened on the front half shell  2  of the housing, has a tensioning shaft  9  and a plurality of supporting and spacer bolts passing through it. The supporting bolts  10 ,  11  are in this case used for fastening a holder  12  (shown in more detail in  FIG. 3 ) of a spring-energy store  13  of the drive mechanism  6 . 
     As shown in  FIG. 2 , a tensioning, apparatus  14  for the spring-energy store  13  (cf.  FIG. 3 ) is arranged on the tensioning shaft  9  and one of the supporting bolts  10  on one of the supporting plates  7 . 
     As shown in  FIG. 3 , the drive mechanism  6  is used for actuating a movable contact  15 , which has a plurality of contact levers  17  (although in the figure only one contact lever is shown), which are supported in a pivotable contact carrier  16  and are arranged parallel to one another. The contact levers  17  are fitted pivotably in a known manner by way of a hinged bolt  18  in the contact carrier  16  and are prestressed by in each case two contact force springs  19 . Flexible conductors  20  are used for connecting the contact levers  17  to a lower terminal bar  21 . The stationary contact  22 , which is associated with the movable contact  15  of the contact arrangement, is connected to an upper terminal bar  23 . The drive mechanism  6  has a drive train comprising a first coupling rod assembly  24  and a second coupling rod assembly  25  as well as a switching shaft  26  for the movable contact  15 . Furthermore, the drive mechanism  6  includes the spring-energy store  13 , by which the energy for switching the switch on and off, i.e. for closing and opening the contacts  15 ,  22 , can be stored, a switching mechanism  27  for latching the spring-energy store  13  in its tensioned state and a switching mechanism  28  for latching the drive train when the contacts  15 ,  22  are closed and the tensioning apparatus  14  for tensioning the spring-energy store  13 . 
     The way in which the switching mechanism for latching the spring-energy store functions has already been described in detail in the document DE 101 20 783 C1, with the result that no more detail is given at this juncture. However, it is noted that the tensioning apparatus  14  is coupled to the spring-energy store  13  during a tensioning phase of the spring-energy store  13  via a lever system  29  and is decoupled from the lever system  29  during a latching phase of the spring-energy store  13 . 
     A part of the tensioning apparatus is the tensioning shaft  9 , which can be rotated by way of a manual drive  31  (illustrated in more detail in  FIGS. 4 to 11 ). 
     As shown in  FIG. 4 , the manual drive  31  comprises two supporting plates  32  (only one is shown in the figures), a ratchet wheel  33 , a transport pawl  34 , a detent pawl  35  and an arrangement  36 , which is coupled to the transport pawl, for actuating the transport pawl. 
     The supporting plates  32  of the manual drive are held fixed in position on the supporting framework by way of the tensioning shaft  9  and the supporting bolt  10 . The ratchet wheel  33  is arranged fixedly on the tensioning shaft  9 . The detent pawl  35  is held pivotably on the supporting plates  32  of the manual drive  31  by way of a first spacer bolt  37  and is prestressed in resilient fashion against the ratchet wheel  33  by way of a first contact-pressure spring  38 . 
     The arrangement  36  for actuating the transport pawl  33  comprises an actuating device  39  in the form of a tension lever and a coupling train  40  for coupling the tension lever to the transport pawl. The stationary pivot bearing for the tension lever is in this case formed by the supporting bolt  10 . 
     The coupling train  40  in this case has a first lever  41 , which is articulated on the tension lever by way of a slot/bolt joint  30 , and two second levers  42  (only one is shown in the figures), which are capable of pivoting about the rotary spindle of the ratchet wheel, the transport pawl  34  being held pivotably on the second levers  42  by way of a second spacer bolt  43  and being prestressed likewise in resilient fashion against the ratchet wheel  33  by way of a second contact-pressure spring  44 . 
     A supporting lever  45  is fastened on the supporting plates  32  of the manual drive  31 , and a pawl lever  46  is articulated on the supporting lever  45  in a manner in which it is capable of pivoting about a stationary pivot spindle  47  in the form of a pin and is prestressed, by way of a dead-center spring  48 , in resilient fashion against a guide face  49  of the tension lever. The dead-center spring is in this case supported on a first arm  50  of the pawl lever  46  in such a way that the spring force of the dead-center spring  48  first acts on the pawl lever in the counterclockwise direction. 
     The pawl lever  46  and the guide face  49  together form an inhibiting mechanism  51  for the tension lever. 
     The guide face  49  has a cutout  52 , whose inner sides form a recessed first section  53  and a projecting second section  54 . 
     The pawl lever  46 , which is capable of pivoting about the stationary pivot spindle  47  and is supported on the dead-center spring  48 , has a second arm  55 , which interacts with the guide face. 
     As shown in  FIGS. 4 to 11 , the actuating device  39  in the form of the tension lever is capable of being moved over, during a first tensioning phase (tensioning excursion shown in  FIGS. 4 to 8 ), counter to the force of two restoring springs  56  out of a rest position (cf.  FIG. 2 ) into an end position (cf.  FIG. 8 ) and, in a second actuation phase (return excursion shown in  FIGS. 9 to 11 ), under the force of the restoring springs  56  out of the end position back into the rest position. One free end of the restoring springs  56  in this case engages in a bore  57  of the actuating device  39 , while the other free end is supported on in each case one of the supporting plates  32 . 
       FIGS. 4 to 8  show the movement sequence of the arrangement for actuating the transport pawl during the first actuation phase, i.e. during the tensioning excursion of the actuating device. 
     As shown in  FIGS. 4 and 5 , the second arm  55  of the pawl lever first, under the force of the dead-center spring  48 , bears against a curved section  58  of the guide face. In this phase of the movement sequence, the transport pawl  34  drives the ratchet wheel  33  and therefore rotates the tensioning shaft  9  in the counterclockwise direction. In this case, the spring-energy store  13  is tensioned to, a certain extent, as is described in detail in the document DE 101 20 783 C1. 
       FIG. 6  shows the actuating device  39  in a first intermediate position; when this first intermediate position is reached, a projecting edge  59  of the second arm  55  of the pawl lever engages in the cutout  52  and therefore in the movement path of the recessed first section  53 . If in this phase the tensioning excursion is interrupted, it is no longer possible for the actuating device  39  to rotate back in the direction of the rest position since the pawl lever blocks the actuating device in the clockwise direction by engaging in the cutout  52 . 
     As shown in  FIGS. 7 and 8 , the projecting edge  59  of the pawl lever continues to slide along the projecting section of the guide face out of the movement path of the recessed section  53 . 
     In a second intermediate position of the actuating device  39 , the pawl lever then assumes a position in which the dead-center point of the dead-center spring  48  is exceeded and therefore the spring force of the dead-center spring acts on the pawl lever in the opposite direction. The pawl lever, as shown in  FIG. 8 , comes to bear against a first stop  60 . This first stop  60  is formed by a pin, which is fastened on the supporting lever  45  and which at the same time forms the abutment for the dead-center spring  48 . 
     When the end position of the actuating device  39  shown in  FIG. 8  is reached, the detent pawl  35  engages in a cutout between two teeth of the ratchet wheel and therefore blocks the ratchet wheel in the clockwise direction. 
     In the second actuation phase shown in  FIGS. 9 to 11 , in which the actuating device  39  is moved over out of the end position back into the rest position under the force of the restoring springs  56 , the second arm  55  of the pawl lever slides on a second stop  61  protruding into its movement path. This second stop  61  is formed by a pin, which is fastened on the first lever  41  of the coupling train  40 . 
     By way of the interaction with the second stop  61 , the pawl lever  46  again pivots beyond the dead-center point of the dead-center spring and again comes to bear against the curved section  58  of the guide face  49 . 
     At the same time as this, as shown in  FIG. 9 , the transport pawl  34  in the second actuation phase slides over the next (in the clockwise direction) tooth of the ratchet wheel  33  which is blocked by the detent pawl  35  and, as shown in  FIG. 10 , engages in the next (in the clockwise direction) cutout of the ratchet wheel shortly before the rest position of the actuating device is reached. The arrangement for actuating the transport pawl is therefore ready for the next tensioning excursion. 
     Eight completely performed tensioning excursions are required for the complete tensioning and latching of the spring-energy store  13 . 
     In order to ensure that the transport pawl and therefore the tensioning shaft  9  is not rotated still further by further tensioning excursions, at the end of the eighth tensioning excursion the engagement of the transport pawl in the next (in the clockwise direction) cutout is prevented. For this purpose, as shown in  FIG. 11 , a cam  62  is formed on the ratchet wheel  33 , which has in total ten teeth and therefore also ten cutouts, and a journal  63  of the transport pawl  34  is associated with said cam. This cam  62  extends over two teeth and protrudes in the radial direction of the ratchet wheel beyond the outer edge of the teeth in such a way that the transport pawl  34  on the eighth return excursion, i.e. in the second actuation phase, pivots out of the movement path of the teeth and cannot engage in the cutout between these two teeth which are covered by the cam  62 . 
     As shown in  FIG. 3 , a display element  65  is coupled to a main pawl  64  of the switching mechanisms  27  which has already been described in detail in the document DE 101 20 783 C1, and this display element  65  signals the state of the spring-energy store  13 . This display element  65  signals as early as shortly before the end of the eighth tensioning excursion that the spring-energy store  13  is completely tensioned. In this phase of the eighth tensioning excursion, the main pawl  64  of the switching mechanism  27  has already experienced an excessive excursion behind a semi-shaft  66  acting as a stop, but a scanning roller  67  of a roller lever  68  of the lever system  29  has not yet become decoupled from the peripheral edge of a cam disk  69 , with the result that the spring-energy store  13  cannot yet be latched in its tensioned position. The circuit breaker  1  is therefore not yet ready to switch on. 
     In order to prevent the eighth tensioning excursion from being interrupted before the end by the operator owing to the display of the display element, the first intermediate position of the actuating device  39  in the form of the tension lever is selected in such a way that it is reached on the eighth tensioning excursion before the display element  65  signals that the spring-energy store  13  is completely tensioned. 
     If the operator of the tension lever interrupts the tensioning excursion once the first intermediate position has been reached, the tension lever is blocked against rotating back into its rest position. In this case, the tension lever staying in position indicates to the operator that it has not completely performed the tensioning excursion. 
     The second intermediate position is selected in such a way that the tension lever is only released again when the roller lever  68  is decoupled from the peripheral edge of the cam disk  69  and therefore the tensioned spring-energy store  13  is actually latched. 
     It is furthermore known from the document DE 101 20 783 C1 that the roller lever  68  is coupled to the cam disk  69  again once the switching mechanism  27  has been released and that the cam disk  69  completes its full rotation through 360° with this coupling and reaches its initial position (illustrated in  FIG. 4 ) again. The tensioning shaft  9 , on which the cam disk  69  is arranged in a manner in which it is fixed against rotation, and the ratchet wheel  33  therefore also assume their initial position (illustrated in  FIG. 4 ) again. 
     Blocking of the actuating device  39  in the form of the tension lever advantageously takes place not only on the eighth (last) tensioning excursion, but also on every other tensioning excursion, with the result that the operator of the actuating device  39  is prevented from performing the tensioning excursions incompletely. 
     Example embodiments being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Low-voltage circuit breaker 
           2 ,  3  Half shells of the housing of the low-voltage circuit breaker 
           4  Arc-quenching chambers 
           5  Supporting framework 
           6  Drive mechanism 
           7 ,  8  Supporting plates of the supporting framework 
           9  Tensioning shaft 
           10 ,  11  Supporting bolts 
           12  Holder of a spring-energy store 
           13  Spring-energy store 
           14  Tensioning apparatus for the spring-energy store  13   
           15  Movable contact 
           16  Pivotable contact carrier 
           17  Contact lever 
           18  Hinged bolt 
           19  Contact-force springs 
           20  Flexible conductors 
           21  Lower terminal bar 
           22  Stationary contact 
           23  Upper terminal bar 
           24  First coupling rod assembly of the drive mechanism 
           25  Second coupling rod assembly of the drive mechanism 
           26  Switching shaft 
           27  Switching mechanism for latching the spring-energy store  13  in its tensioned state 
           28  Switching mechanism of latching the drive train when the contacts  15 ,  22  are closed 
           29  Lever system 
           30  Slot/bolt joint 
           31  Manual drive for the tensioning shaft 
           32  Supporting plates 
           33  Ratchet wheel 
           34  Transport pawl 
           35  Detent pawl 
           36  Arrangement for actuating the transport pawl 
           37  First spacer bolt 
           38  First contact-pressure spring 
           39  Actuating device 
           40  Coupling train 
           41  First lever of the coupling train 
           42  Second lever of the coupling train 
           43  Second spacer bolt 
           44  Second contact-pressure spring 
           45  Supporting lever 
           46  Pawl lever 
           47  Stationary pivot spindle 
           48  Dead-center spring 
           49  Guide face 
           50  First arm of the pawl lever 
           51  Inhibiting mechanism 
           52  Cutout 
           53  Recessed first section of the cutout 
           54  Projecting second section of the cutout 
           55  Second arm of the pawl lever 
           56  Restoring spring 
           57  Bore of the actuating device 
           58  Curved section of the guide face 
           59  Projecting edge of the pawl lever 
           60  First stop for the pawl lever 
           61  Second stop for the pawl lever 
           62  Cam of the ratchet wheel 
           63  Journal of the transport pawl 
           64  Main pawl 
           65  Display element 
           66  Stop 
           67  Scanning roller 
           68  Roller lever 
           69  Cam disk