Abstract:
An installation switching device having at least one pole current path comprises two stationary contact pieces; a moving contact bridge including two moving contact pieces forming a double-break pole with the two stationary contact pieces; a contact pressure spring exerting a pressure on the moving contact bridge in a closing direction of the moving contact bridge; a pusher configured to act on the moving contact bridge counter to the pressure of the contact pressure spring in an opening direction, the pusher including a slide and a striking pin disposed moveably relative to the moving contact bridge and to one another in a movement direction of the moving contact bridge; a switch latch having a latching point; an operating lever configured to act on the pusher; and an electromagnetic release having an impact armature.

Description:
[0001]    This is a U.S. National Phase Application under 35 U.S.C. § 171 of International Application No. PCT/EP2007/009670 filed on Nov. 8, 2007, which claims priority to German Application No. DE 10 2006 055 007.2, filed on Nov. 22, 2006. The International Application was published in German as WO 2008/061630 on May 29, 2008 under PCT 21(2). 
         [0002]    The invention relates to a double-break installation switching device. 
     
    
     BACKGROUND 
       [0003]    Installation switching devices of this generic type, for example motor protection switches, have at least one pole current path, comprising two stationary contact pieces and two moving contact pieces which are arranged on a moving contact bridge and form a double-break pole switch with two contacts. 
         [0004]    In this case, a pusher acts on the contact bridge in the opening direction, and a contact compression spring acts on it in the closing direction. 
         [0005]    Furthermore, installation switching devices of this generic type have an electromagnetic release whose armature not only acts on the contact bridge via the pusher in the opening direction but also unlatches the latching point of a switch latch when a short-circuit current occurs in the pole current path, as a result of which the switch latch permanently acts on the contact bridge in the opening sense, against the force of the contact compression spring, via an operating lever. 
         [0006]    Immediately after the striking on the contact bridge and thus the breaking of the short-circuit current in the pole current path, the electrodynamic recoil of the electromagnetic release collapses, and the force of the contact compression spring once again acts on the contact bridge in the direction of its closed position. 
         [0007]    As a result of the greater mechanical inertia of the switch latch, compared with that of the system comprising the armature and the pusher, the operating lever lags behind the pusher movement in order to hold the contacts permanently open by means of the switch latch. 
         [0008]    In unfavorable conditions, it is possible for the contacts to have already been closed again by the contact compression spring before the switch latch can provide permanent opening via the operating lever and the pusher. This is then referred to as contact bouncing, which is undesirable. 
       SUMMARY OF THE INVENTION 
       [0009]    An aspect of the present invention is therefore to provide an installation switching device of this generic type with a better dynamic response for breaking short-circuit currents, while avoiding contact bouncing. 
         [0010]    According to the invention, the pusher therefore comprises a slide and a striking pin which are arranged such that they can move relative to the contact bridge and relative to one another essentially in the movement direction of the contact bridge, with the arrangement comprising the slide, the striking pin, the contact bridge, the operating lever and the armature being designed such that, in the event of a short circuit, the armature strikes the contact bridge via the striking pin in the opening direction, with the slide lagging behind the striking pin before the operating lever permanently holds the contact bridge in the open position via the slide against the contact pressure force. 
         [0011]    The pusher according to the invention is therefore formed from two parts. This makes it possible for a first part of the pusher, specifically the striking pin, to be accelerated very quickly by the armature in the event of a short circuit, because of its small mass, thus striking the contact bridge very quickly. 
         [0012]    Once the contact bridge has been struck and the short-circuit current has thus been broken, the effect of the force of the armature on the striking pin also ends. The contact bridge is now pushed in the closing direction again, by the force of the contact compression spring. 
         [0013]    The slide which, according to the invention, lags behind the striking pin as the second part of the pusher, can brake this opposing movement of the contact bridge, in such a way that the contact bridge is prevented from closing the contacts before the operating lever finally holds the contact bridge permanently in the open position, via the slide, with the operating lever lagging even further behind the striking pin because of the greater mechanical inertia of the switch latch. 
         [0014]    The installation switching device according to the invention therefore results in very rapid striking of the contact bridge in the event of a short circuit, while at the same time preventing contact bouncing. 
         [0015]    According to one particularly advantageous embodiment, the contact bridge is guided in a first opening of the slide such that it can move in its movement direction. 
         [0016]    A further embodiment is highly advantageous, in which the striking pin is guided in a second opening of the slide such that it can move in the movement direction of the contact bridge. The guidance of the striking pin in the second opening of the slide is in this case advantageously designed such that, during its movement in the opening direction of the contact bridge and because of a friction force that exists between the striking pin and the slide, the striking pin drives this in the opening direction, lagging behind it. 
         [0017]    According to one advantageous further embodiment, the slide has a first step in the first opening, which step forms an upper stop for the contact bridge. This ensures a very compact design. When the slide strikes the contact bridge during its movements, which lag behind the striking pin, in the opening direction of the contact bridge, then, via the first step which acts as the upper stop, it has a braking effect on the opposing movement of the contact bridge in the closing direction. 
         [0018]    The slide advantageously has a second step on its outside, which step forms a point of action for the operating lever. 
         [0019]    Furthermore, the arrangement comprising the striking pin, slide and contact bridge is advantageously designed such that the mass of the slide is equal to or greater than the sum of the masses of the striking pin and contact bridge. This results in the advantage that the force of the resetting spring on the contact bridge is less than the force which acts on the contact bridge as a result of the genetic energy of the striking pin during opening. 
         [0020]    Even more advantageous is an embodiment in which the slide has a third step in the first opening in which the contact bridge is guided, which step forms a lower stop for the contact bridge. During its impact movement in the opening direction, the contact bridge first of all drives the slide a certain amount in the opening direction on the third step, and thus assists its movement, which lags behind the striking pin, in the opening direction. When the contact bridge is once again moved in the opposite direction, in the closing direction, as a result of the force of the contact compression spring after the electrodynamic recoil of the electromagnetic release has collapsed, then, in the embodiment described here, the slide is advanced even further in the opening direction and its first step strikes the contact bridge even earlier, thus resulting in even more effective braking of the opposing closing movement of the contact bridge. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0021]    The invention as well as further advantageous refinements and improvements of the invention will be explained and described in more detail with reference to the drawings, which illustrate three exemplary embodiments of the invention, and in which: 
           [0022]      FIG. 1   a  shows a functional layout of an installation switching device according to the invention, with a pusher according to the invention in the rest position, 
           [0023]      FIG. 1   b  shows a section view of the pusher according to the invention as shown in  FIG. 1  a in the rest position, 
           [0024]      FIG. 2   a  shows a functional layout of an installation switching device according to the invention with a pusher according to the invention shortly after the occurrence of a short-circuit current, 
           [0025]      FIG. 2   b  shows a section view of the pusher according to the invention as shown in  FIG. 2   a,    
           [0026]      FIG. 3   a  shows a functional layout of an installation switching device according to the invention with a pusher according to the invention at the maximum deflection of a contact bridge in the opening direction, 
           [0027]      FIG. 3   b  shows a section view of the printer according to the invention as shown in  FIG. 3   a,    
           [0028]      FIG. 4   a  shows a functional layout of an installation switching device according to the invention with a pusher according to the invention during the opposite movement of the contact bridge and of the slide, 
           [0029]      FIG. 4   b  shows a section view of the pusher according to the invention as shown in  FIG. 4   a,    
           [0030]      FIG. 5   a  shows a functional layout of an installation switching device according to the invention with a pusher according to the invention at the start of the effect of the switch latch on the operating lever, 
           [0031]      FIG. 5   b  shows a section view of the pusher according to the invention in the position shown in  FIG. 5   a,    
           [0032]      FIG. 6   a  shows a functional layout of an installation switching device according to the invention with a pusher according to the invention in the case of permanent opening by the switch latch via the operating lever, 
           [0033]      FIG. 6   b  shows a section view of the pusher according to the invention in the position shown in  FIG. 6   a,    
           [0034]      FIG. 7  shows a section view of a pusher according to the invention according to a further embodiment, and 
           [0035]      FIG. 8  shows a section view of a pusher according to the invention according to a third embodiment. 
       
    
    
       [0036]    Identical elements or assemblies or elements or assemblies having the same effect are in each case allocated with the same reference numbers in  FIGS. 1 to 8 . 
       DETAILED DESCRIPTION  
       [0037]      FIG. 1  shows an installation switching device  1  according to the invention with a pole current path  2  between an input terminal  3  and an output terminal  4 . By way of example, this could be a pole current path of a three-pole motor circuit breaker, whose other two pole current paths are designed in a corresponding manner. 
         [0038]    The pole current path  2  comprises two stationary contact pieces  5 ,  6  and two moving contact pieces  8 ,  9 , which are arranged on a moving contact bridge  7  and form a double-break contact point  10 . The contact bridge  7  is acted on by a contact compression spring  11  in the closing direction, see the direction arrow S. The contact bridge  7  can be acted on in the opening direction, see the direction arrow O, by a pusher  12  which acts on the opposite side of the contact bridge  7  to the contact compression spring  11 . 
         [0039]    The pole current path  2  also has a thermal release  113  and an electromagnetic release  13  with an armature which, when a short-circuit current occurs in the pole current path  2 , acts on the contact bridge  7  in the opening direction via the pusher  12  as a result of electrodynamic recoil, indicated by the line of action  14 . At the same time, in the event of a short circuit, the armature of the electromagnetic release  13  also acts on a switch latch  15  and unlatches its latching point, indicated by the line of action  16 , such that the switch latch  15  permanently acts on the pusher  12  in the opening direction of the contact bridge  7 , as indicated by the line of action  18 , and via an operating lever  17 , in the unlatched state. 
         [0040]    The function of the thermal release  113 , which likewise acts on the switch latch  15  in the event of an overcurrent, as indicated by the line of action  114 , is in principle known and is not the subject matter of the present invention. The thermal release  113  is illustrated here only for the sake of completeness. 
         [0041]    By way of example, the mechanical system comprising the switch latch  15  and the operating lever  17  may be a toggle lever system with a two-stage latch. The operating lever  17  is in the form of a double-armed lever whose first lever arm  171 , on which the switch latch  15  acts, and whose second lever arm  172 , which interacts with the pusher  12 , form an obtuse angle with one another, and the operating lever  17  is mounted such that it can rotate in a fixed-position rotating shaft  173 , as a result of which the operating lever  17  acts as a direction-shinning lever. 
         [0042]    The mechanical system just described has a certain amount of mechanical inertia, as a result of which a certain amount of time, for example 2 to 5 ms, passes after unlatching before the operating lever  17  acts on the pusher  12  in order to act permanently on it in the opening direction. 
         [0043]    In contrast, the time before the contact bridge  7  is struck directly by the armature of the electromagnetic release  13  is much shorter and, for example, is only 1 ms. 
         [0044]    If no further measures were to be taken, it would therefore be possible for the contact bridge  7  to be forced back again to its original position, in the closed position, just by the resetting force of the contact compression spring  11 , and for the contact point  10  to be closed again in this way before the operating lever  17  can still act with the free end of its second arm  171  on the pusher and can thus act permanently on the contact bridge  7  in the open position. 
         [0045]    The measures according to the invention, which are taken in order to prevent this, will be described in the following text. 
         [0046]    The pusher  12  is formed in two parts. It comprises a slide  19  and a striking pin  20 . As can be seen from the section illustration of  FIG. 1   b,  the pusher  12  is an elongated component with an approximately cylindrical or cuboid basic shape. 
         [0047]    The contact bridge  7  is guided such that it can move in its closing direction and in its opening direction in a first, slot-like opening  21  in the slide  19 , which is open at the bottom towards the narrow face of the slide  19 . 
         [0048]    The striking pin  20  is likewise guided such that it can move in the closing direction and opening direction of the contact bridge  7  in a second, channel-like opening  22  in the slide  19 . It overhangs the slide  19  upwards, in the direction of the point of action of the impact armature. 
         [0049]    A first step  23  is formed in the first opening  21  of the slide  19 , and is used as an upper stop for the contact bridge  7 . A second step  24  is formed on the outside of the slide  19 , and is used as a point of action for the operating lever  17 . 
         [0050]    The operation of the arrangement according to the invention when a short-circuit current occurs will now be explained in the following text. When a short-circuit current occurs, see  FIG. 2   a,  then, as a result of the electrodynamic recoil of the electromagnetic release  13 , its armature strikes the striking pin  20  of the pusher  12 , indicated by the impulse arrow I in  FIG. 2   a.  The striking pin  20  is accelerated downwards in the opening direction O, driving the contact bridge  7  in the opening direction O. The moving contact pieces  8 ,  9  are thus disconnected from the stationary contact pieces  5 ,  6 , and the double contact point  10  is opened. As a result of the mass inertia, the downwards movement of the striking pin  20  continues, even when the armature has returned to its rest position again after the collapse of the short-circuit current with the contact point  10  open.  FIG. 3   a  shows this state, in which the contact bridge  7  has reached its maximum deflection in the opening direction O, driven by the striking pin  20 . The contact compression spring  11  is completely compressed. 
         [0051]    The slide  19  is driven by the striking pin  20  in the opening direction O, lagging behind the striking pin  20 , as a result of a small sliding-friction force between the striking pin  20  and the slide  19  in the interior of the second opening  22 . 
         [0052]    When the maximum deflection of the contact bridge  7  in the opening direction O has been reached, this is acted on upwards in the closing direction S again, by virtue of the resetting force of the contact compression spring  11 , and is moved, see  FIG. 4   a.  An opposite movement of the contact bridge  7  takes place upwards for a certain amount of time, with the slide  19  moving downwards. When the first step  23  of the slide  19  strikes the contact bridge  7  moving it in the opposite direction to it, then, first of all, the upward movement of the contact bridge  7  is slowed down, in which case, however, after a short delay time, the contact bridge  7  drives the slide  19  on its further upward movement, in the closing direction, via the first step  23 . This situation is illustrated in  FIGS. 5   a  and  5   b.    
         [0053]      FIG. 5   a  illustrates that point in time at which the inertia-dependent delay of the mechanical system comprising the switch latch  15  and the operating lever  17  has ended, and the operating lever  17 , which is in the form of a toggle lever, is rotated clockwise by the switch latch  15 , indicated by the action arrow K. The contact point  10  is still open. 
         [0054]    During a further upward movement in the closing direction S, the second step  24  on the slide  19  strikes the operating lever  17 , which is rotated further in the clockwise direction. The switch latch  15  is unlatched and—indicated by the arrow K—holds the operating lever  17  permanently in a position such that it firmly holds the slide  19 , via the second step  24 , so far in the opening direction  0  that the contact point  10  remains permanently opened. As can be seen, no contact bouncing has occurred. 
         [0055]    The opening of the contact bridge  7  by the armature of the electromagnetic release  13  preferably takes place in the manner described above for low-level and medium-level short-circuit currents. In the case of high-level short-circuit currents, for example of more than 1 to 2 kA, the opening takes place via electrodynamic propulsion between the stationary and moving contact pieces  5 ,  6 ;  8 ,  9 . This is also referred to as opening by electrodynamic propulsion between the contact pieces. This opening by electrodynamic propulsion takes place more quickly than opening by the armature, since so mechanically moving intermediate parts are involved, as represented by the armature for example, and, in consequence, no inertia-dependent time delay occurs, either. In this case, the armature initially lags behind the contact bridge. The prevention of the premature closure of the contact point after the initial fast opening as a result of the electrodynamic propulsion then takes place in the subsequent time, however, in precisely the same way as that described above. 
         [0056]      FIG. 7  shows a further embodiment of a slide  19   a  according to the invention. In this case, the first opening  21  is closed at the bottom by a web  25 . The movement range of the contact bridge  7  is thus bounded in the first opening  21  between the first step  23 , which acts as an upper stop, and the web  25 . The advantageous effect of the web  25  consists in that, during the downward movement of the striking pin  20 , this acts as a lower stop and actively drives the slide  19  downwards in the opening direction. It therefore supports the lagging driving of the slide  19  downwards in the opening direction O by the striking pin  20 . 
         [0057]      FIG. 8  shows a further variant. There, two steps  26 , each with inclined side surfaces  27 , are fitted at the open end of the opening  21 , instead of a continuous web in the first opening  21 . In this case, the slide  19  is driven by the contact bridge  7  via the inclined surfaces  27 . 
         [0058]    Thus, overall, the installation switching device according to the invention comprises two moving systems. The first moving subsystem comprises the striking pin  20  and the contact bridge  7 , and the second moving subsystem comprises the slide  19 . The two moving subsystems must be designed such that the force of the contact compression spring  11  on the contact bridge  7  is less than the force which the striking pin  20  experiences as a result of the kinetic energy resulting from the impact on it of the armature of the electromagnetic release  13 . The mass of the slide  19  must therefore be greater or at least equal to the sum of the masses of the striking pin  20  and the contact bridge  7 . 
       LIST OF REFERENCE SYMBOLS  
       [0059]      1  Installation switching device 
         [0060]      2  Pole current path 
         [0061]      3  Input terminal 
         [0062]      4  Output terminal 
         [0063]      5 ,  6  Stationary contact pieces 
         [0064]      7  Moving contact bridge 
         [0065]      8 ,  9  Moving contact pieces 
         [0066]      10  Contact point 
         [0067]      11  Contact compression spring 
         [0068]      12  Pusher 
         [0069]      13  Electromagnetic release 
         [0070]      14  Line of action 
         [0071]      15  Switch latch 
         [0072]      16  Line of action 
         [0073]      17  Operating lever 
         [0074]      18  Line of action 
         [0075]      19  Slide 
         [0076]      20  Striking pin 
         [0077]      21  First opening 
         [0078]      22  Second opening 
         [0079]      23  First step 
         [0080]      24  Second step 
         [0081]      25  Web 
         [0082]      26  Step 
         [0083]      27  Inclined slide surface 
         [0084]      113  Thermal release 
         [0085]      114  Line of action 
         [0086]      171  First lever arm 
         [0087]      172  Second lever arm 
         [0088]      173  Rotation axis