Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation, under 35 U.S.C. § 120, of copending international application No. PCT/EP03/01087, filed Feb. 4, 2003, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German patent application No. 102 08 057.7, filed Feb. 25, 2002; the prior applications are herewith incorporated by reference in their entirety. 

   BACKGROUND OF THE INVENTION 
   Field of the Invention 
   Refrigerators are usually equipped with a switch for sensing an opening or closing of their door or doors. 
   A known type of switch used here is constituted by mechanically actuated electric switches that are installed on the housing of the refrigerator, in the vicinity of the door, and interact with an operating cam on the door. Such a switch may be fixed, for example, in a front metal or plastic strip on the front side of the refrigerator, just above or beneath a door, and can be actuated via a through-passage in the front strip. The switch is actuated via a body that is fixed to the door. In this system, the switch, in the case of repair, can usually be removed without any destructive effect, and a new switch can be installed at the same location. 
   One disadvantage of this solution is the mechanical sensitivity of the switch, in particular of its moveable push rod that is to be actuated by the door. The push rod may be damaged, in particular, during transportation of such a refrigerator. If the door is not positioned precisely, e.g. because the hinge-mounting of the door has been changed during set-up of the refrigerator or because the door has been subjected to heavy loading, it may be the case that the push rod and the switching body of the door do not overlap to a sufficient extent and the switch thus does not perform a switching function. 
   A further disadvantage may arise if the switch is installed beneath a refrigerating/freezer compartment from which water can escape, for example, during the defrosting cycle. The necessity for the moveable push rod gives rise to a gap in the switch-enclosing housing, through which water can possibly penetrate into the interior of the switch and come into contact with live parts. 
   In order to counteract the problems associated with inaccurate positioning of the door and, in particular, the ingress of moisture, it is known to use, in a door-opening sensor, a magnetically actuated switch, in particular a reed switch, in combination with a magnet fastened on the door. Such a switch may be installed, for example, by being set in foam in the basic structure of the refrigerator, in the vicinity of the door. The disadvantage of this solution is that, in the case of malfunctioning, such a switch cannot be exchanged without any destructive effect. 
   In order to eliminate the disadvantage of the lack of access to the magnetically actuated switch, it has been proposed to fit the switch on a printed circuit board which bears the control electronics of the refrigerator and is accommodated in a plastic housing fastened on the front side of the refrigerator. In the case of repair, the latter can be carried out by virtue of the plastic housing being removed and then the defective magnetically controlled switch being unsoldered and a replacement switch being soldered in. 
   In an improved configuration, the magnetically actuated switch, rather than being soldered directly onto the printed circuit board carrying electronic components, is soldered onto an auxiliary printed circuit board that, for its part, is provided with electric lines and/or a plug in order to produce the connection to the electronics printed circuit board. This has the advantage that the magnetically actuated switch can be placed in the interior of the plastic housing at a different location from the electronics printed circuit board itself. It is still unsatisfactory, however, that, even with this configuration, the switch can only be positioned within the interior of the housing in which the electronics printed circuit board is also located. This switch can thus only be used to sense the opening and closing of the door that is disposed directly above or beneath the housing. In particular in the case of a refrigerator with a number of doors, this known solution cannot be used for a door that is not adjacent to the housing of the electronics printed circuit board. 
   SUMMARY OF THE INVENTION 
   It is accordingly an object of the invention to provide a door-opening sensor and a refrigerator equipped therewith which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which is not susceptible to the influence of moisture, can be installed in a refrigerator housing in largely any desired position in the vicinity of the door and can easily be exchanged. 
   With the foregoing and other objects in view there is provided, in accordance with the invention, a door-opening sensor for a refrigerator. The sensor contains a contactlessly actuated switch, and a housing enclosing the switch. The housing has a releasable fastener for fastening the housing in an opening. Plug-in contacts are electrically connected to the switch and provide an electrical contact-connection to the switch being accessible on one side of the housing. 
   Since the switch of the sensor is configured with a dedicated housing and also with plug-in action, it can be installed at any desired location of the refrigerator housing where an opening for accommodating the switch can be produced. 
   The switch, preferably a reed switch, is expediently installed on a printed circuit board which is accommodated in the housing and of which a periphery bears the plug-in contacts which are required for the contact-connection of the switch. The plug-in contacts are preferably configured as conductor-track portions on the periphery of the printed circuit board. 
   The housing may be open on its rear side, with the result that the printed circuit board can readily be pushed into the housing via the open rear side. Penetration of moisture via the open rear side is not to be expected if suitable sealing is provided between the front region of the housing and the periphery of the opening that encloses this region. This sealing may be assisted, in particular, by a collar that runs around the housing and is provided in order, in the installed state of the door-opening sensor, to butt against the front side of the wall bearing it. A sealing element may be clamped in between the collar and the front side. 
   In order to make it easier for the door-opening sensor to be placed in the opening, it is provided that, on its periphery which is directed toward the front side of the housing, the printed circuit board is retained, e.g. by clamping, such that it cannot be moved in the direction perpendicular to the surface and, on its periphery which bears the plug-in contacts, it has freedom of movement in the direction perpendicular to its surface. This firm clamping, on the one hand, and the freedom of movement, on the other hand, can be achieved, in particular, with the aid of grooves, in the interior of the housing, which converge in the direction of the front side of the housing and guide the printed circuit board. This freedom of movement makes it possible to compensate for any possible positional inaccuracy between the opening and contacts that are disposed on it and are provided for connection to the plug-in contacts of the switch. 
   In order to make it easier for the housing to be installed on a refrigerator, it is additionally possible to provide a plug-in bushing which can be installed on the inside of the wall opening thereof, into which the housing can be pushed and which has contacts which complement the plug-in contacts of the switch. 
   These contacts may be accommodated, in particular, in a contact component that is retained in a sleeve of the plug-in bushing, between a shoulder and a latching hook. 
   The invention also relates to a refrigerator having at least one door-opening sensor of the type explained above. 
   Other features which are considered as characteristic for the invention are set forth in the appended claims. 
   Although the invention is illustrated and described herein as embodied in a door-opening sensor and a refrigerator equipped therewith, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
   The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic, perspective view of a refrigerator according to the invention; 
       FIGS. 2 and 3  are diagrammatic, sectional views showing a section through a door-opening sensor according to the invention in two planes that are perpendicular to one another; 
       FIGS. 4 and 5  are diagrammatic, sectional views showing a section through a wall of the refrigerator with a plug-in bushing installed on the wall, each section being taken along section planes analogous to those of  FIGS. 2 and 3 ; and 
       FIGS. 6 and 7  are diagrammatic, sectional views showing sections through the door-opening sensor installed in the wall, along the same section planes. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a perspective view of a refrigerator equipped with door-opening sensors according to the present invention. The refrigerator has two doors  50 ,  51  each closing, for example, a normal refrigerating compartment and a chiller compartment or a normal refrigerating compartment and a freezer compartment  52 ,  53 . A door-opening sensor  54  is disposed on the front side of the housing of the refrigerator, beneath each of the compartments  52 ,  53 , such that it is directed toward a bottom periphery of the respective door  50 ,  51 . The door-opening sensors  54  are disposed approximately centrally on the front side of the housing of the refrigerator, with the result that they have the same level of sensitivity irrespective of the side of the housing on which the doors  50 ,  51  are hinge-mounted. 
   A magnet which is to be sensed in each case by the door-opening sensor  54  is incorporated in the door  50 ,  51  in a position which is located opposite the door-opening sensor  54 . It would, of course, also be possible for the door-opening sensors  54  to be disposed at other locations on the front side of the housing of the refrigerator, in particular also in openings made in the inner container of the refrigerator. 
     FIG. 2  shows a section through a door-opening sensor  54  in a horizontal plane in relation to the configuration of the door-opening sensors  54  which are shown in  FIG. 1 . 
     FIG. 3  shows a section through the same door-opening sensor along a vertical plane. The section plane of  FIG. 3  is designated III—III in  FIG. 2 , and the section plane of  FIG. 2  is designated II—II in  FIG. 3 . 
   The door-opening sensor  54  is essentially constructed from three parts: a reed switch  1 , a printed circuit board  2 , on which the reed switch  1  is soldered, and a housing  3 , which accommodates the printed circuit board  2  with the reed switch  1 . 
   The housing  3 , which is produced in one piece from plastic, has a substantially cuboidal body  17 , which is open on the rear side and is enclosed on four side walls by an encircling collar  8 . Narrow side walls  18  of the body  17  have on their inside, as is shown in  FIG. 3 , a groove  19  which tapers from the open rear side to the closed front side of the body  17  and serves for guiding and securing of the printed circuit board  2 . The printed circuit board  2  is retained by these grooves  19  in an essentially play-free manner in the region of the front side and with freedom of movement in the region of the rear side. 
   On the open rear side, the body  17  is extended by two flexible arms  20 , which extend from the edges between one of the broad side walls  21  and the narrow side walls  18  and each bear a latching hook  24  at their free ends. The arms  20  can be displaced outward when the printed circuit board  2  is pushed into the groove  19  and are adapted to the length of the printed circuit board  2  such that the latching hooks  24  engage behind the rear edge  22  of the printed circuit board  2  when the front edge  23  of the latter reaches the narrow front end of the grooves  19 . It is thus possible to latch the printed circuit board  2  in the housing  3 . 
   The shape of the latching hook  24  engaging behind the rear edge  22  of the printed circuit board  2  is selected, in adaptation to the freedom of movement of the printed circuit board in the rear region of the groove  19 , such that, in any position which the printed circuit board  2  can assume, the engagement between the latching hook  24  and the rear edge  22  is not lost without the arm  20  being bent at the same time. 
   The printed circuit board  2  bears the reed switch  1  on a surface that is directed away from the arms  20 . Conductor tracks  6  extend over the surface of the printed circuit board  2  from the connections of the reed switch  1  to conductor surfaces  7  on the rear edge  22  of the printed circuit board  2 , these conductor surfaces being wider than the conductor track  6  and serving as plug-in contacts for the electrical contact with the plug-in bushing illustrated in  FIGS. 3 and 4 . 
   The narrow side walls  18  bear, on their outer sides, two clasps or clips  14  which can be pressed together in the plane of  FIG. 2 . As will become clear in a later stage in the text, these serve for the releasable fastening of the housing  3  by latching in an opening. 
     FIGS. 4 and 5  each show a section through a plug-in bushing  32  which is installed in an opening  30  of a wall  4  of the refrigerator and is provided in order to push the housing  3  into the same and to make contact with the reed switch  1 . 
   The plug-in bushing  32 , which is formed from plastic, is constructed from two approximately cuboidal, hollow portions, referred to as plug-in portion  33  and wire-feed portion  34 . The plug-in portion  33  has an open front side that is directed toward the wall  4  and is enclosed by an encircling flange  35 . The flange  35  is adhesively bonded firmly to the inside of wall  4 . The cavity of the plug-in portion  33  is higher and wider than an opening  30  behind which it is disposed. 
   Broad side walls  36  of the plug-in portion  33 , of which one can be seen from the view in  FIG. 4 , bear a plurality of ribs  15  and  16 , which project into the interior of the cavity of the plug-in portion  33 . Two of these ribs, the ribs  16 , extend over the entire depth of the plug-in portion  33 , and their height is dimensioned such that the broad side walls  21  of the housing  3  introduced into the plug-in portion  33  are retained in a play-free manner, or subjected to a slight clamping-in action, by them. The shorter ribs  15  are of such a length that they do not reach the rear side of the housing  3 , once introduced, and of such a height that they guide the rear edge of the printed circuit board  2  between them, and direct it into an accommodating slot  37  of a contact component  5 , when the printed circuit board is plugged in. As can be seen in  FIG. 5  in particular, the contact component  5  is retained in a sleeve  40  that is formed in a wall  39  that separates the portions  33 ,  34  off from one another. In order to fix the contact component  5  in the plug-in direction of the housing  3 , on the one hand, use is made of two latching hooks  41 , which are connected to two of the short ribs  15  via flexible tongues  42  and can be displaced to the side when the contact component  5  is pushed into the sleeve  40 . On the other hand, a shoulder  43  formed in the sleeve  40  limits the movement capability of the contact component  5  in the direction of the opening  30  and thus prevents the contact component from being drawn out together with the printed circuit board  2  if the door-opening sensor has to be exchanged. 
   Two wires  44  for the contact-connection of the reed switch  1  extend from the contact component  5 , through the wire-feed portion  34 , to a non-illustrated lead-through, at which they pass out of the wire-feed portion  34  into an insulating-foam layer  13 , which encloses the outer sides of the plug-in bushing  32 . The lead-through is formed by one or two cutouts in a side wall of the wire-feed portion  34  which are adjacent to a rear wall  31 , which is separate from the rest of the wire-feed portion  34 . 
   The door-opening sensor according to the invention is installed, in the first instance, by the flange  35  of the plug-in bushing  32  being adhesively bonded to the inside of the wall  4 , enclosing the opening  30 . At this point in time, it is possible for the contact component  5  already to be provided with connection wires and to be latched in the sleeve  40  and for the rear wall  31  to be fitted on the wire-feed portion  34 ; however, it is also possible for the contact component  5  and the rear wall  31  to be fitted only when the plug-in bushing  32  has been installed on the wall  4 . 
   The rear wall  31  secures the wire-feed portion  34  against the penetration of the foam  13  when the door-opening sensor is encapsulated by the foam. 
   Once the plug-in bushing  32  has been installed on the wall  4 , the housing  3  can be introduced into the plug-in portion  33  through the opening  30 . 
     FIGS. 6 and 7  show, once again in sections taken along two planes which are perpendicular to one another, and correspond to the planes II—II and III—III, the door-opening sensor installed on the wall  4  of the refrigerator. The clips  14 , which are pressed together when the housing  3  is pushed in to the opening  30 , have returned to their original configuration, with the result that the housing  3  is fixed on the wall  4  by clamping between the collar  8  and the clips  14 . 
     FIG. 6  shows a sealing ring  9  clamped in-between the collar  8  and the wall  4 . The sealing ring may be provided as required if there is a high risk of moisture penetrating into the plug-in portion  33 , e.g. because the region of the wall  4  in which the opening  30  is located may be subjected to wetting by defrosting water forming in the interior of the refrigerator. 
   In order to exchange the door-opening sensor in the case of malfunctioning, it is sufficient for the front region of the housing  3 , this region projecting beyond the outer surface of the wall  4 , to be gripped, e.g. using pliers, and drawn out of the opening  30 . It is then possible, by virtue of the arms  20  being bent, for the printed circuit board  2  to be removed from the housing  3  and exchanged. All that is then required is for the housing  3  to be pushed into the opening  30  again.

Technology Category: 5