Patent Publication Number: US-2007103887-A1

Title: Switching device and arrangement for detecting various positions of a door element

Description:
The present invention relates to a switching device, especially a door contact switch according to the preamble of claim  1 . The invention further relates to an arrangement for detecting different positions of a door element according to the preamble of claim  6 . The invention further relates to a household appliance according to the preamble of claim  11 .  
      In electrical household appliances a function can be provided which switches on or switches off an interior light and/or other electrical loads when a door is opened. This function is more appropriately triggered by means of a so-called door contact switch since this can provide a reliable switching signal according to the opening position of the door. Door contact switches of this type usually comprise a control element which can be displaced against the force of a spring, which is in operative connection with an electric switch. If the door is brought from its closed position into an open position, the control element, for example a striker which can be displaced by spring force, is actuated. The switch is hereby triggered and delivers a different switching signal compared with the pressed position of the striker. Door contact switches of this type are used in refrigerators for switching on an interior light and can activate cooking chamber lighting in cooker appliances as soon as a baking oven door is opened.  
      It can possibly be desirable to dispense with switching on the interior lighting or cooking chamber lighting when opening the door. Such a function is known as the so-called Sabbath circuit which prevents any lighting from being switched on when the baking oven door is opened. Such a Sabbath mode can be desirable or necessary for religious reasons. Methods and devices for operating cooker appliances with a so-called Sabbath mode are known, among other things, from U.S. Pat. No. 5,808,278 and from U.S. Pat. No. 6,066,837. In this case, any manual influence on certain functions of the cooking appliance during certain definable time intervals is prevented by means of electronic circuits.  
      It is an object of the present invention to be able to simply influence a mechanical switching function when opening a door element of an electrical household appliance.  
      This object is solved in a switching device having the features of the preamble of claim  1  by an operative connection between a mechanical switching element and an electrical switch actuated thereby being separable. The switching device according to the invention thus makes it possible to deactivate as required an electrical switching function normally triggered by the switching element. Such a switching function can, for example, be cooking chamber lighting which can be switched on by opening a baking oven door in a cooking appliance. The electrical switching function can, for example, also switch off an electrical hot air fan of an oven muffle of a cooking appliance when a door to the cooking chamber is opened. In this way, the switching-on and switching-off function for the cooking chamber lighting and/or for further loads can be deactivated by separating the operative connection between switching element and electrical switch.  
      A wide range of switching functions can be triggered by means of the switching device according to the invention. In an electrical refrigeration for example, the switching function can effect the switching on of an interior lighting when opening a front door. The separable operative connection between the switching element and the electrical switch can have the result that the interior lighting is no longer switched on as soon as the door is opened.  
      A particular advantage of the mechanically deactivatable switching function is that by using the switching device according to the invention, it is possible to provide electrical household appliances which have or allow a so-called Sabbath function. Since some religions do not allow any electrical lighting to be switched on during certain time intervals, for example, during the Sabbath after dusk has fallen, the problem can arise that a cooking appliance which has a switching function for switching on a cooking chamber light on opening the baking oven door can no longer be used during the Sabbath. Otherwise, it could occur, for example, that a cooking process was started before dusk had fallen and continued beyond this. Then, it would no longer be possible to open the baking oven door without previously switching off the appliance. However, switching on the appliance again to finish cooking also would no longer be possible since this is also forbidden during the Sabbath. The switching device according to the invention allows all these switching functions to be deactivated simply and inexpensively by separating the operative connection between the switching element and the electrical switch before the cooking process is begun.  
      In principle, the switching device according to the invention is suitable for building into all electrical appliances wherein the opening of a door should trigger a switching function. Refrigerators or freezers can also be provided with a Sabbath function in this way where the light basically remains switched off even when the door is opened. In addition, in many other household appliances switching functions associated with an opening of a door element can be deactivated.  
      The switching element can optionally execute a substantially translational or rotational movement between its at least two operating positions. In the case of a translational movement of the switching element, this can preferably be a striker which can be displaced linearly against a spring force which is displaced by contact with a door element. The housing element can in particular be an openable housing flap of the household appliance, for example, a front door or front flap of a cooking chamber of a cooking appliance or a refrigerator door or the like. In this way, the switching device forms a door contact switch consisting of a switch, a spring, a housing and a striker which utilise the position of the door in cooperation.  
      The electrical switch can in this way optionally close a contact or trigger an electrical or electronic unit positioned subsequently. When the door element is opened or at least partly opened, the switching element or the striker is pushed by the action of the spring force into its first operating position which is thus a rest position. When the door element is closed, the switching element or striker is pressed into its second operating position. The electrical switch can especially have a displaceable switching pin which can be actuated by a cam on the external circumference of the displaceable striker.  
      In a first embodiment of the invention, the striker can be executed as rotatable about its longitudinal axis so that the operative connection between the switching element and the electrical switch can be separated by turning the striker through a certain angle. The cam on the outer circumference of the displaceable striker thus must not describe the entire circumference of the striker but only a circumferential segment so that by simply turning the striker, the operative connection between the actuatable switching pin of the switched and the displaceable striker is separated. A user can thus actively or passively switch the door interrogation by simply turning the striker.  
      An advantageous variant can provide that two or more cams are provided on the outer circumference of the striker so that by a respective turn of the striker through an angle of about 90 degrees, for example, it is possible to activate or deactivate the door contact switch. These at least four different angular positions of the striker are preferably defined by a suitable locating element which can prevent any unintentional twisting of the striker.  
      An arrangement according to the invention for detecting at least two different positions of a movable door element having the features of claim  6  provides that an operative connection between the door element and the switching device according to the invention can be separated. In this arrangement, the striker can be brought out of the region of engagement of the door element, for example, by displacement or lowering. The striker can optionally also be lowered by means of a link mechanism, similar to a ball pen mechanism, and can thus be brought out of the region of engagement of the door element. As a result of lowering the striker, the door no longer reaches the striker in the closed state. The switching function normally triggered with a displacement of the striker from its first operating position into the second operating position is no longer triggered. As a result of the striker being released by the user, the door again reaches the striker in the closed state. The switching function which can thereby be triggered, is triggered again.  
      An alternative variant provides that the operative connection between the switching device and the door element can be separated by exposing a depression disposed in the door element for receiving the striker. The depression can be exposed, for example, by means of a slider so that when the door element is closed and the slider is opened, the striker can dip into the depression exposed hereby.  
      The invention has the advantage that the user of the electrical appliance can himself determine whether the recognition of the door end position is switched on or not. The user can hereby also directly influence various functions coupled to this door interrogation. For example, this can be switching on or off lighting, energy saving, heating or a hot air fan motor or the like.  
      The switching device according to the invention or the arrangement according to the invention is especially suitable for incorporation into a household appliance according to any one of claims  11  to  13 .  
      Further preferred and advantageous variants and further developments of the invention can be deduced from the dependent claims and the following description of the figures. 
    
    
      The invention is explained hereinafter with reference to a preferred exemplary embodiment where reference is made in detail to the appended drawings. In the figures:  
       FIG. 1  is a schematic front view of a cooking appliance with opened front flap and cooking chamber accessible at the front,  
       FIG. 2  is a schematic perspective diagram of an embodiment of a switching device according to the invention and  
      FIGS.  3  to  5  are schematic diagrams of the switching device according to  FIG. 2  in respectively different operating states. 
    
    
      The cooking appliance  10  according to  FIG. 1  has a cooking chamber  12  which is accessible from outside in the horizontal direction by means of a downwardly pivotable front flap  14 . Located at the side on a frame  16  of a housing front  18  of the cooking appliance  10  is a door contact switch  20  which, when the front flap  14  is closed, is covered thereby and thus cannot be seen from outside. The door contact switch  20  is switched by the front flap  14  and thus has at least two operating states. A first operating state characterises a closed front flap  14  whereas a second operating state characterises an at least partly opened front flap  14 . The door contact switch  20  can, for example, switch a cooking chamber light  22 , an electrical hot air fan  24  or other electrical loads of the cooking appliance  10 .  
      According to the present invention, the door contact switch  20  can be deactivated so that the switching functions normally provided by opening and closing the front flap  14  are no longer triggered.  
      The operating mode of the deactivatable switching functions is explained in detail with reference to a preferred exemplary embodiment of the door contact switch  20  with reference to FIGS.  2  to  5 .  
      An alternative variant for deactivation of the door contact switch  20  by means of a slider  50  arranged in the front flap  14  is explained further below.  
      The door contact switch  20  according to the invention comprises a switching element  26  which is in separable operative communication with an electrical switch  38 . In the exemplary embodiment shown, the switching element  26  comprises a linearly displaceable striker  48  which is held in a first operating position L 1  by means of spring force. The first operating position L 1  is illustrated in  FIGS. 2 and 3  respectively. In the exemplary embodiment the spring is embodied as a coil spring  28  which is arranged around the outer circumference of the striker  48  and supports this against a housing projection  30 .  
      A front side  32  of the striker  48  can be contacted by the closing front flap  14  whereby, when the front flap  14  closes completely, the striker  48  is displaced to the left against the force of the coil spring  28  into a second operating position L 2  (see  FIG. 4 ). As a result, a trip cam  34  located on the outer circumference of the striker  48  acts on a switching pin  36  of the electrical switch  38 . The electrical switch  38  can, for example, be a conventional micro-switch whose electrical contact is opened or closed by linear displacement of the switching pin  36 . The linear displacement of the striker is converted by means of the trip cams  34  into a linear displacement of the switching pin  36  of the electrical switch perpendicular hereto.  
      The afore-mentioned operative connection between the displaceable striker  48  and the electrical switch  38  is hereby realised. In each of the two operating positions L 1  and L 2  the electrical switch  38  remains deactivated since its switching pin  36  is no longer reached by one of the trip cams  34 .  
       FIG. 5  illustrates the possible separation of the operative connection between switching element  26  and electrical switch  38 . By twisting the striker  48  about its longitudinal axis, the trip cam  34  can be brought from the region of engagement with the switching pin  36  whereby the switching function of the door contact switch  20  according to the invention can be deactivated. The striker  48  is then further activated and linearly displaced by the opening or closing front flap  14  but the switching function of the electrical switch  38  is no longer triggered as a result of the trip cam  34  no longer actuating the switching pin  36 . The door contact switch  20  is deactivated in this way and no longer triggers any electrical switching function. In this way, the operative connection between the switching element  26  and the electrical switch  38  can be separated according to the invention.  
      In order to stabilise the activated or deactivated operative connection between the switching element  26  and the electrical switch  38  of the door contact switch  20 , a locating spring  40  is provided which is anchored in the housing  42  of the door contact switch  20  and acts on a corresponding recess or elevation on the outer circumference of the striker  48 . The locating spring  40  can, for example, by a leaf spring or the like whose free end can engage in separate recesses  44  on the outer circumference of the striker  48 . In this case, the two recesses  44  are preferably separated from one another by a web  46  or the like over which the locating spring  40  must slide when the striker  48  is twisted about its longitudinal axis. In this way, the striker  48  can be stabilised in at least two possible angular positions which each characterise an activation or deactivation of the door contact switch  20 .  
      A preferred embodiment of the door contact switch  20  according to the invention can provide that the striker  48  can be twisted in each case in a pre-determined direction through 90 degrees. A defined angular position of the locating spring  40  can ensure that any twisting in the other direction is blocked. In this variant, at least four separate recesses  44  are provided on the outer circumference of the striker  48 , each separated from one another by webs  46  so that the locating spring  40  can in each case be in engagement with one of the four recesses  44  whereby respectively one of the two possible states of the door contact switch  20  can be defined. In this way, the operation of the door contact switch  20  is very much simplified since the user need not take into consideration whether the striker  48  is located in the correct angular position. The striker  48  only needs to be twisted by 90 degrees further in the defined direction to thereby activate or deactivate the operative engagement between the trip cam  34  and the switching pin  36 .  
      It can optionally be advantageous if the possible angular positions of the striker  48  are characterised by means of small coloured markings so that the user can read off in each case whether the door contact switch  20  is activated or deactivated. This makes it possible to assess the operating state of the door contact switch  20  without the cooking appliance  10  first needing to be switched on.  
      An alternative possibility for deactivating the switching functions of the door contact switch  20  consists in no longer displacing the striker  48  into its second operating position L 2  when the front flap  14  is completely closed but staying in its first operating position L 1  at all times. This can be achieved, for example, by a slider  50  being opened on the inside of the front flap  14  pointing towards the door contact switch  20  so that the part of the striker  48  projecting from the frame  16  of the cooking appliance  10  can dip into a depression  52  which had previously been closed by the slider  50 . This depression  52  is preferably so deep that even when the front flap  14  is completely closed, the striker  48  is not pressed but is held by the force of the coil spring  28  in its first operating position L 1 .  
     REFERENCE LIST  
       10  Cooking appliance  
       12  Cooking chamber  
       14  Front flap  
       16  Frame  
       18  Housing front  
       20  Door contact switch  
       22  Cooking chamber light  
       24  Hot air fan  
       26  Switching element  
       28  Coil spring  
       30  Housing projection  
       32  Front side  
       34  Trip cam  
       36  Switching pin  
       38  Electrical switch  
       40  Locating spring  
       42  Housing  
       44  Recess  
       46  Web  
       48  Striker  
       50  Slider  
       52  Depression  
      L 1  First operating position  
      L 2  Second operating position