Abstract:
An electrical switch with a main current path and an auxiliary current path comprises a first stationary contact piece, a first moveable contact piece, a contact lever, a second stationary contact piece, a second moveable contact piece, a contact carrier, a toggle switch, a first intermediate lever, a control lever, a second intermediate lever, a latching lever, a release lever configured to form a latching connection with the latching lever at a latching point, and a tripping spring.

Description:
[0001]    This is a U.S. National Phase Application under 35 U.S.C. §171 of International Application no. PCT/EP2007/009296, filed on Oct. 26, 2007, which claims priority to German Patent Application No. DE 10 2006 051 807.1, filed on Nov. 3, 2006. The International Application was published in German as WO 2008/052702 A1 on May 8, 2008 under PCT 21 (2). 
     
    
       [0002]    The invention relates to an electrical switch. 
       BACKGROUND 
       [0003]    Such a switch is described, for example, in DE 195 26 591 A1 and in DE 195 26 592 C2. 
         [0004]    It has a main current path, in which a main contact point is located, which comprises a stationary and a movable contact piece, the movable contact piece being fastened on a contact lever arm mounted pivotably on a fixed rotary spindle. 
         [0005]    Furthermore, a generic switch has an auxiliary current path, in which an isolating contact point, also referred to as an auxiliary contact point, is located, which likewise comprises a stationary and a movable contact piece, the movable contact piece being fastened on a contact carrier mounted pivotably on a fixed rotary spindle, with the current being commutated from the main current path onto the auxiliary current path in the event of a short circuit. 
         [0006]    The main contact point and the auxiliary contact point can be actuated using a switching lever and a switching mechanism, which is mounted with its individual components in a printed circuit board holder. 
         [0007]    The contact lever is a twin-armed lever, whose arm lying opposite the movable contact piece is acted upon by a control lever, whose other end is connected in articulated fashion via a pivot pin to a first intermediate lever, and the other end of the intermediate lever is connected in articulated fashion to a second intermediate lever, which is articulated on the toggle switch. 
         [0008]    The link pin, with which the two intermediate levers are connected to one another, is guided in a slot of a rotatably mounted latching lever. 
         [0009]    A release lever is also provided, with which the latching lever forms a latching point. 
         [0010]    The release elements, i.e. thermal and magnetic releases, act on the switching mechanism at the release lever, the levers being arranged and interacting with one another in such a way that, in the event of renewed making, the switching sequence “auxiliary contact leading, main contact lagging” is implemented. 
         [0011]    A contact pressure spring acts at the contact lever and attempts to press the movable contact piece with a given contact force against the fixed contact piece. 
         [0012]    In the case of known generic switches, a tripping spring in the form of a compression spring acts on the control lever and attempts to press said control lever against the force of the contact pressure spring in the direction of tripping of the main contact point. The tripping spring in this case requires a large amount of space, and its spring force on the control lever always acts in the same direction. In this case it must still be able to exert a sufficiently great force on the control lever to compensate for the force of the contact pressure spring, even in the partially unstressed state. In this case, the compressive force of the tripping spring acts directly on the latching point and determines the unlatching force which needs to be applied by the thermal release for unlatching purposes. 
         [0013]    Thus, in known generic switches there is the problem that the tripping spring needs to satisfy two opposing requirements. In order to ensure safe tripping, the force which it exerts on the control lever should be as great as possible. In order to ensure safe unlatching by the thermal release, however, this force should be as small as possible. In known generic switches, a compromise is always made, and neither of the requirements is entirely met. 
       SUMMARY OF THE INVENTION 
       [0014]    An aspect of the present invention is to provide a generic switch in such a way that a great force is exerted on the control lever and, at the same time, a small force is exerted on the latching point. 
         [0015]    In accordance with the invention, the tripping spring therefore acts on the pivot pin, which connects the control lever and the first intermediate lever, and, via the pivot pin, loads the control lever in the direction of tripping of the main contact point, the introduction of force of the tripping spring onto the pivot pin being designed in such a way that a first, relatively small partial force acts in the direction of the latching point, and a second, relatively great partial force acts on the control lever. 
         [0016]    In accordance with the invention, the tripping spring therefore no longer acts directly on the control lever, but on the pivot pin, which connects the control lever to the first intermediate lever. As a result, the direction of the introduction of force is selectable and can thus be designed in such a way that the force of the tripping spring is split into two components, of which one component acts in the direction of the latching point and a second component acts on the control lever in the direction of tripping. The introduction of force is in this case designed in such a way that the first partial force acting in the direction of the latching point is as small as possible and only the second partial force acting on the control lever is as great as possible. 
         [0017]    In accordance with a particularly advantageous embodiment of the invention, the tripping spring is a torsion spring, also known as a leg spring, whose first leg is supported on a fixed point and whose second leg is used for the introduction of force onto the pivot pin. 
         [0018]    Torsion springs are spiral springs which are wound in three dimensions with a linear torque characteristic. The introduction of force or torque takes place via the legs at the start and end of the spring. They can be matched in a variety of ways to the respectively provided physical conditions. By using a torsion spring to implement the present invention, the restricted space in the interior of the electrical switch according to the invention can therefore be utilized particularly well. 
         [0019]    Very advantageous in this case is an embodiment in which the torsion spring is wound around the fixed rotary spindle of the contact carrier of the isolating contact point. Then, the rotary spindle of the contact lever acts as a working mandrel, against which the torsion spring bears with its inner coil opening and is held thereby. The rotary spindle of the contact carrier of the isolating contact point thus has an additional function, and no separate holder for the torsion spring is required. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The invention and further advantageous configurations and improvements of the invention will be explained and described in more detail with reference to the drawings, which illustrate an exemplary embodiment of the invention and in which: 
           [0021]      FIG. 1  shows the switching mechanism of a switch according to the invention in the closed position, and 
           [0022]      FIG. 2  shows the switching mechanism shown in  FIG. 1  with the main and auxiliary contacts open. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The switching mechanism has a main contact point  10  with a fixed contact piece  11  and a movable contact piece  13 , which is fastened on a contact lever  12 . 
         [0024]    The contact lever  12  is mounted rotatably on a fixed rotary spindle  14  and is in the form of a twin-armed lever, whose first arm  15  bears the contact piece  13  and whose second arm  16  is acted upon by a control lever  17 , which moves the contact lever  12  out of the making position (see  FIG. 1 ) into the tripping position (see  FIG. 2 ). 
         [0025]    A contact pressure spring (not illustrated) acts at the contact lever and attempts to press the movable contact piece  13  against the fixed contact piece  11  with the contact force indicated by the arrow  50 . 
         [0026]    The control lever  17  is connected to a first intermediate lever  19  via a pivot pin  18 . Said intermediate lever  19  is connected in articulated fashion to a second intermediate lever  21  via a link pin  20 , which intermediate lever  21  is articulated on a toggle switch  24  with a switching handle  25  on an articulated spindle  23 . The toggle switch  24  is mounted on a fixed spindle  22 . 
         [0027]    The link pin  20  is guided movably in a slot  26  of a latching lever  27 . The latching lever  27  is mounted fixed in position in such a way that it can rotate about a rotary spindle  28 . The latching lever  27  forms a latching point  31  with a release lever  30 , which is mounted in such a way that it can rotate about a fixedly mounted spindle  29 . 
         [0028]    The release lever  30  is in the form of a twin-armed lever, whose first arm  301 , which is inclined towards the latching point, bears a tab  302 , which, together with a tab  271  of the latching lever  27 , forms the latching point  31 . The second arm  303 , which points away from the latching point  31 , of the release lever  30  bears a tab  304 . The thermal release(s) of the switch act on this tab  304 , for example via slides (not illustrated here). As a result of the action of the thermal releases, the release lever  30  is pivoted in the clockwise direction in the event of an operation of the release, with the result that the tab  302  releases the tab  271 , as a result of which the latching point  31  is unlatched. In this case, the thermal releases need to overcome at least the force with which the tab  271  acts on the tab  302 , which is therefore referred to as the unlatching force. 
         [0029]    A fixed rotary spindle  33  is provided between the connecting line which connects the fixed rotary spindle  28  of the latching lever  27  and the fixed spindle  22  of the toggle switch  24 , and the contact point  10 , with a contact carrier  34 , which bears a contact lever  35 , being mounted on said rotary spindle  33 . 
         [0030]    The movable contact piece  36  of an isolating contact point  37  is fastened at the free end of the contact lever  35 . The isolating contact point  37  has a fixed contact piece  38 , which can be connected, fixed in position and electrically conductively, to the fixed contact piece  11  of the main contact point  10 , indicated by a dashed connecting line  138 . 
         [0031]    The contact carrier  34  is in the form of a twin-armed carrier. One arm  39 , which faces the main contact point  10 , bears the contact lever  35  and the movable contact piece  36 . The second arm  40 , which projects in the opposite direction, has a projection  49 . 
         [0032]    A tab  48 , which interacts with the projection  49  on the contact carrier  34  in such a way that the isolating contact point  37  opens after the opening of the main contact point  10  in the event of an opening operation of the main contact point  10  and is already closed prior to the closing of this main contact point  10  in the event of the closing of the main contact point  10 , is integrally formed on the control lever  17 . 
         [0033]    The connecting line between the link pin  20  and the articulated spindle  23  which has the reference numeral  46  runs, in the tripping position shown in  FIG. 2 , below the connecting line  47 , which runs between the link pin  20  and the fixed spindle  22  of the toggle switch  24 . This is the first stable position of the switching mechanism in the tripping position. 
         [0034]    In the making position shown in  FIG. 1 , the connecting line  46  runs above the fixed spindle  22 . This is the second stable position of the switching mechanism in the making position. 
         [0035]    A torsion spring  51  is wound around the fixed rotary spindle  33  of the contact carrier  34 . A first leg  52  of the torsion spring  51  is supported on a fixed point  53 . This fixed point  53  can be a projection or a depression on the inner side of the housing wall of the switch, but it may also be a mounting point on the printed circuit board holder of the switching mechanism. 
         [0036]    A second leg  54  of the torsion spring  51  is supported at its free end against the pivot pin  18 , which connects the control lever  17  to the first intermediate lever  19 . The introduction of the spring force onto the pivot pin  18  therefore takes place via the second leg  54  of the torsion spring  51 . The spring force which is introduced onto the pivot pin  18  perpendicular to the second leg  54  at the point of touching contact between the leg  54  and said pivot pin  18  is denoted by an arrow  55 . It is split into a first, relatively small partial force, denoted by the arrow  56 , which is directed into the first intermediate lever  19 , and into a second, relatively great partial force, denoted by the arrow  57 , which attempts to shift the control lever  17  in the direction of “opening of the main contact point  10 ”. 
         [0037]    Only the first, relatively small partial force  56 , which is directed into the first intermediate lever  19 , generates the unlatching force at the latching point  31 . This is relatively small, with the result that only a small release force needs to be applied by the thermal release, which force acts on the release lever  30  at the tab  304 . 
         [0038]    The second, relatively great partial force  57  is so great that it can overcome the contact pressure force  50  and can open the main contact point  10  and the isolating contact point  37  via the control lever  17 . If appropriate, the second partial force  57  of the torsion spring  51  can be assisted in this case by the force of a further tension spring, which is articulated firstly on the control lever  17  and secondly on the second arm  40  of the contact carrier  34 . This further tension spring is not illustrated here, but it is described, along with its function, in the abovementioned documents DE 195 26 591 and DE 195 26 592. The further tension spring is also not essential to the invention and not necessary for the operation of a switch according to the invention. 
         [0039]    In the event of release, the release lever  30  would therefore be pivoted in the clockwise direction and in the process the latching point  31  would be released with the small unlatching force  56  being overcome. As a result, the link pin  20  in the slot  26  of the latching lever  27  is released and the control lever  17  can be pressed away from the fastening plane defined by the fixed contact piece  11  of the main contact point  10  and the rotary spindle  14  of the contact lever  12  as a result of the second, relatively great partial force  57 . In this case, the control lever  17 , via a guide pin  58 , carries along the second arm  16  of the contact lever  12  and pivots the latter counter to the contact pressure force  50  and in the counterclockwise direction in such a way that the main contact point  10  is opened. 
         [0040]    The arrangement of the link chain, which is formed from the first intermediate lever  19 , the second intermediate lever  21  and the toggle switch  24  and interacts with the latching lever  27  via the link pin  20 , which is guided in the slot  26 , is affected in such a way that the toggle switch  24  is pivoted in the clockwise direction and the latching lever  27  is immediately pivoted into its latching position again, with the result that, if the thermal release has cooled down again and has moved back into its initial position, the latching point  31  is again latched. This position is illustrated in  FIG. 2 . 
         [0041]    From the position illustrated in  FIG. 2 , renewed making of the switching mechanism is possible by the rotation of the switching handle  25  and therefore the toggle switch  24  in the counterclockwise direction. In this case, the torsion spring  51  is then also stressed again. 
       LIST OF REFERENCE SYMBOLS 
       [0042]      10  Main contact point 
         [0043]      11  Fixed contact piece of main contact point 
         [0044]      12  Contact lever of main contact point 
         [0045]      13  Movable contact piece of main contact point 
         [0046]      14  Rotary spindle 
         [0047]      15  First arm of contact lever 
         [0048]      16  Second arm of contact lever 
         [0049]      17  Control lever 
         [0050]      18  Pivot pin 
         [0051]      19  First intermediate lever 
         [0052]      20  Link pin 
         [0053]      21  Second intermediate lever 
         [0054]      22  Fixed spindle 
         [0055]      23  Articulated spindle 
         [0056]      24  Toggle switch 
         [0057]      25  Switching handle 
         [0058]      26  Slot 
         [0059]      27  Latching lever 
         [0060]      271  Tab 
         [0061]      28  Rotary spindle of latching lever 
         [0062]      29  Spindle of release lever 
         [0063]      30  Release lever 
         [0064]      301  First arm of release lever 
         [0065]      302  Tab 
         [0066]      303  Second arm of release lever 
         [0067]      304  Tab 
         [0068]      31  Latching point 
         [0069]      33  Fixed rotary spindle of contact carrier  34   
         [0070]      34  Contact carrier 
         [0071]      35  Contact lever of isolating contact point 
         [0072]      36  Movable contact piece of isolating contact point 
         [0073]      37  Isolating contact point 
         [0074]      38  Fixed contact piece of isolating contact point 
         [0075]      138  Connecting line 
         [0076]      39  First arm of contact carrier 
         [0077]      40  Second arm of contact carrier 
         [0078]      46  Connecting line  20 - 23   
         [0079]      47  Connecting line  20 - 22   
         [0080]      48  Tab 
         [0081]      50  Contact pressure force 
         [0082]      51  Torsion spring, tripping spring 
         [0083]      52  First leg of torsion spring 
         [0084]      53  Fixed point 
         [0085]      54  Second leg of torsion spring 
         [0086]      55  Spring force 
         [0087]      56  First partial force 
         [0088]      57  Second partial force 
         [0089]      58  Guide pin 
         [0090]      49  Projection