Patent Publication Number: US-2023160575-A1

Title: Add-on piece for fastening to a panel element

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the priority of German Patent Application, Serial No. 102022201501.0, filed Feb. 14, 2022, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference in its entirety as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to an add-on piece for fastening to a panel element, a panel system having such an add-on piece and a cooking appliance having such a panel system. 
     In the prior art, for example in DE 10 2016 218 807 A1, two systems of panels in the case of cooking appliances are different. These two systems comprise on the one hand a so-called self-supporting switch front and on the other hand a so-called sandwich construction. 
     The self-supporting switch front has a base part that can consist of different materials, such as for example plastic, aluminum, steel or stainless steel and for example can be brushed, lacquered or polished. Positioning elements and fastening elements are integrated into the base part and said elements are used on the one hand for fastening and positioning the base part to a cooking appliance and on the other hand for fastening and positioning add-on pieces to the base part. The design freedoms in the case of a self-supporting switch front are limited, since on account of design requirements it is not possible for example to attach recessed switch handles. It is complex to assemble conventional add-on pieces on the base part, especially as their fastening is not to be visible and further design elements must be attached so as to cover the fastening. As a result, additional process steps, such as for example welding or adhering are necessary. 
     The sandwich construction is used in particular in the case of high value appliances having greater design requirements and for the use of recessible switch handles. Said sandwich construction has a panel carrier on which all add-on pieces are mounted and a design element that is fastened to the panel carrier. In the prior art, in other words for example in EP 2 390 403 A1, a wet adhesive is used for fastening to the panel carrier. Conventional add-on pieces are fastened to the panel carrier with the aid of complex fastening elements, such as for example screw connections, setting and bending plates, snap hooks or eyelets. In the publication EP 2650 613 A1, an add-on piece is fastened to the panel carrier by an adhesive. As a result, long drying times and high assembling costs are involved. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved add-on piece for fastening to a panel element. 
     According to one aspect of the invention, an add-on piece for fastening to a panel element includes a base body, a fastening element, and a guiding element and a mating guiding element which are configured to guide the fastening element with respect to the base body such that during assembling of the add-on piece on the panel element, the fastening element moves away from the base body and comes into engagement with the panel element for fastening the add-on piece to the panel element. 
     Advantageously, the add-on piece can be pushed against the panel element during the assembling. As a result, the fastening element is moved away from the base body with the aid of the guiding element and the mating guiding element and engages in the panel element. The assembling of the add-on piece includes in this case only one assembling step i.e. pushing the add-on piece against the panel element. As a result, assembling of the add-on piece is simplified and assembling time is reduced when compared e.g. to an adhering process that requires applying the adhesive, precisely positioning the add-on piece on the panel element and holding the add-on piece in this position until the adhesive has hardened. 
     The configuration of the add-on piece renders it possible by way of example to fasten recessible add-on pieces to the panel element, in particular to a self-supporting switch front under high design requirements. These can be for example that the fastening of the add-on piece to the panel element is not visible or the add-on piece is connected to the panel element in a manner flush with the surface. 
     To ensure clarity, it is necessary to establish the definition of several important terms and expressions that will be used throughout this disclosure. 
     The term “panel element” is to be understood in particular to be a self-supporting switch front that has an, in particular single, base part, in particular a re-shaped metal part. The base part can have multiple positioning elements and fastening elements to which all the add-on pieces are fastened. Furthermore, the base part is sufficiently rigid in order to support one or multiple add-on pieces. The panel element can, advantageously, be used as a switch front. 
     The term “guiding element” is understood in particular to be a guiding rail on which the fastening element is mounted and is displaceable in a linear manner for assembling the add-on piece on the panel element. 
     The term “mating guiding element” is understood in particular to be a mating element that engages in the guiding rail or encompasses the guiding rail or is mounted in a linear manner on the guiding rail and is displaceable in a linear manner along the guiding rail. 
     The guiding element and the mating guiding element can have by way of example the same cross section profile, wherein “cross section” refers to a section that is perpendicular to the direction along which the relative movability (in particular displaceability) is provided (also referred to below as the “longitudinal direction”). 
     According to another advantageous feature of the invention, the guiding element and the mating guiding element can be configured to guide in a pre-assembled state of the add-on piece to the base body the fastening element such that the fastening element is blocked in a releasable manner from moving away from the base body. In this way, it is advantageously achieved that the fastening element is already fastened to the base body prior to the actual assembling on the base body and it does not need to be held by a person or a robot during the assembling. As a result, the assembling costs can be reduced. 
     The term “pre-assembled state” is understood to be a state in which the fastening element is fastened to the base body with the aid of the guiding element and mating guiding element before the add-on piece is assembled on the panel element. 
     The term “blocked in a releasable manner” is understood in particular to mean a positive locking and/or non-positive locking connection that can be released by way of example in a non-destructive manner. In particular, the releasable connection is provided by an elastic latching connection. 
     According to another advantageous feature of the invention, when the fastening element is engaged with the panel element in an assembled state of the add-on piece, the add-on piece is movable between the pre-assembled state and the assembled state by moving the fastening element away from the base body, with the fastening element being blocked in the assembled state from moving back to the base body. Advantageously, the fastening element can be blocked in a releasable manner from moving back to the base body in the assembled state. 
     This configuration of the add-on piece renders it possible to assemble the add-on piece on the panel element in only one single assembling step in which the add-on piece is pushed against the panel element. The base body is fixed to the add-on piece by preventing the fastening element moving back to the base body. By virtue of the movement being blocked in a releasable manner, it is possible for the add-on piece to be dismantled from the panel element, for example for repair purposes. 
     In the “assembled state”, the fastening element engages for example into a rail, a double folded edge or a cut out of the panel element. In the “assembled state”, the add-on piece can be fixed in six degrees of freedom to the fastening element. 
     The term “blocked in a releasable manner” is likewise here understood in particular to mean a positive-locking and/or non-positive locking connection that can be released by way of example in a non-destructive manner. In particular, the releasable connection is provided by an elastic latching connection. However, the releasability is optional here. 
     According to another advantageous feature of the invention, the movement away and/or the movement back of the add-on piece can be a displacement in a straight line. Of course, a “movement away” and/or “movement back” may also occur along a curve. The “movement back” occurs in the opposite direction to “movement away”. 
     According to another advantageous feature of the invention, the base body can be moved in an assembling direction towards the panel element for the assembling of the add-on piece so that the fastening element and/or one of the guiding element and the mating guiding element comes into contact with the panel element to cause the fastening element to move away from the base body. As a result, the add-on piece can be assembled on the panel element in a simple manner. 
     The term “assembling direction” is understood to be a direction in which the add-on piece is assembled on the panel element. The assembling direction is oriented in particular in a perpendicular manner with respect to the main extension plane of the panel element. 
     According to another advantageous feature of the invention, the guiding element can be a rail and the mating guiding element can have a profile that encompasses the rail. The rail can advantageously have a T-shaped cross section. The profile can have a C-shaped cross section. 
     According to another advantageous feature of the invention, the straight line and/or the rail is inclined with respect to the assembling direction. The incline can be by way of example between 10-80°, advantageously between 30-70°. 
     According to another advantageous feature of the invention, the guiding element and the mating guiding element can latch in a releasable manner with one another for releasably blocking the movement away and/or blocking the movement back or one of the guiding element and the mating guiding element can latch in a releasable manner with a further element. As a result, it is advantageously possible to achieve that the fastening element can be releasably locked with respect to the base body in the pre-assembled and/or assembled state, as described above. 
     Latchability can be provided for example by latching protrusions or protruding sections, which engage in receiving elements, such as for example mating latches, cut-outs, notches, or holes. An elastic embodiment of the latching protrusions or of the protruding sections renders it possible for the guiding element and mating guiding element to be released again. 
     According to another advantageous feature of the invention, at least one of the guiding element and the mating guiding element can be fastened to the base body via a wedge. 
     The wedge can be inclined with respect to the assembling direction. The guiding element and the mating guiding element are preferably fastened to a surface (inclined surface) of the wedge that is facing away from the base body. 
     According to another advantageous feature of the invention, one of the guiding element and the mating guiding element and/or the wedge can be formed as one piece with the base body and/or the respective other one of the guiding element and mating guiding element can be formed as one piece with the fastening element. A one piece embodiment eliminates the need for further assembling steps for fastening the guiding element and the mating guiding element and/or the wedge to the base body. 
     According to another advantageous feature of the invention, the fastening element can include a first fastening element which is guided by the guiding element and mating guiding element with respect to the base body, and a second fastening element, with the first and second fastening elements being arranged on opposite sides of the base body. The add-on piece further includes a further guiding element and a further mating guiding element configured to guide the second fastening element with respect to the base body such that during assembling of the add-on piece on the panel element, the second fastening element moves away from the base body and comes into engagement with the panel element for fastening the add-on piece to the panel element, with the first and second fastening elements moving away from the base body in opposite directions. 
     As a result, it is advantageously achieved that the first and second fastening elements can be brought into engagement simultaneously with the panel element using only one assembling step. Furthermore, the use of two fastening elements renders possible a secure fastening in six degrees of freedom. 
     The first fastening element can come into engagement by way of example with a rail or a double folded edge of the panel element. The second fastening element can come into engagement by way of example with one or multiple cut-outs that are arranged on a single folded edge of the panel element. 
     According to another advantageous feature of the invention, the base body can be formed from two half shells that are connected to one another. A design of the base body from two half shells renders it possible in a simple manner to produce the base body from two injection molded parts. The half shells can be clipped together via latching protrusions, which are arranged on the one half shell, and mating latches which are arranged on the other half shell. 
     According to another advantageous feature of the invention, the base body can have a display facility, in particular a display, an operating element, in particular a switch or a switch receptacle, by way of example a receptacle for a recessible rotary knob, a positioning facility for positioning the panel element with respect to a carcass of the cooking appliance, a communication facility, in particular a WLAN module, a loud speaker facility and/or other fastenings to the appliance, in particular a steam hinge. 
     Furthermore, the at least one add-on piece can be a steam module or a steam hinge. These facilities are advantageously provided when the cooking appliance includes an apparatus for generating steam for the cooking process. The steam module comprises in particular a controller for the above mentioned apparatus. The steam hinge is a hinge for this apparatus. 
     According to another aspect of the invention, a panel system includes a panel element and an add-on piece, wherein the add-on piece can be fastened or is fastened to the panel element through engagement of the fastening element of the add-on piece in the panel element. 
     According to still another aspect of the invention, a cooking appliance, in particular a cooker or baking oven, includes a panel system as described above. In this case, the panel system is assembled on an appliance carcass. 
     Further possible implementations of the invention include also combinations, which are not explicitly mentioned, of features or embodiments that have been previously described or are to be described below with respect to the exemplary embodiments. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantageous embodiments and aspects of the invention are the subject matter of the subordinate claims and of the exemplary embodiments of the invention described below. Furthermore, the invention is explained in detail with the aid of preferred embodiments with reference to the attached figures. 
         FIG.  1    shows a perspective view of only a section of a baking oven in accordance with one embodiment; 
         FIG.  2    shows a perspective view of the rear side of a panel element; 
         FIG.  3    shows the panel element from  FIG.  2   , wherein two add-on pieces are arranged on said panel element, and specifically two switch receptacles; 
         FIG.  4    shows a first housing part of the switch receptacle from  FIG.  3   ; 
         FIG.  5    shows a first fastening element of the first housing part from  FIG.  3   ; 
         FIG.  6    shows a view of the rear side of the fastening element from  FIG.  5   ; 
         FIG.  7    shows a second housing part of the switch receptacle from  FIG.  3   ; 
         FIG.  8    shows a second fastening element of the second housing part from  FIG.  3   ; 
         FIG.  9    shows a view of the rear side of the fastening element from  FIG.  8   ; 
         FIGS.  10  to  12    show in a cross sectional view of the panel element three steps during the assembling of the switch receptacle therein; and 
         FIG.  13    shows a cross sectional view of the panel element with the assembled switch receptacle and a rotary knob recessed therein. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION 
     Like or like-functioning elements are provided with the same reference characters in the figures unless otherwise stipulated. 
       FIG.  1    illustrates a cooking appliance  1  in a perspective view. The cooking appliance  1  that in accordance with an exemplary embodiment is a baking oven comprises a panel system  2  and a carcass  3 . The panel system  2  is fastened to the carcass  3 . The panel system  2  comprises a panel element  4  and one or multiple add-on pieces that are further explained later and can be fastened to the panel element  4 . 
     The cooking appliance  1  comprises on the front side a door  5 . The door  5  can be opened in order to reveal access to a cooking compartment in the interior of the cooking appliance  1 . The panel element  4  of the panel system  2  is arranged above the door  5 . Moreover, the panel system  2  has by way of example two recessible rotary knobs  6 . The rotary knobs  6  can be moved between a first and a second position respectively. In the first position, as illustrated in  FIG.  1   , the rotary knobs  6  protrude forward beyond the panel element  4 , in other words in the depth direction T. In this first position, they can be operated by a user standing in front of the cooking appliance  1 . By way of example, it is thus possible to set the temperature in the cooking compartment. In the second position, they are recessed in the panel element  4 , in other words, they are arranged essentially with their front side flush with the panel element  4 . Symbols  7  can be provided around a respective rotary knob  6  and said symbols, together with a marking  8  on the respective rotary knob indicate information regarding an operating state of the cooking appliance  1 . The symbols  7  can by way of example be printed, adhered or in this case embossed onto the panel element  4 . Moreover, the symbols  7  can be provided by electronic facilities, such as possibly LEDs. The symbols  7  are provided directly on the side  9  of the panel element  4  that is visible to the user (in the present case also referred to as the front side). Furthermore, the panel system  2  can comprise a display  10 . The display  10  which can also be in particular a touch display is configured so as to display information regarding the cooking appliance  1  and/or the food to be cooked that is located therein. 
       FIG.  2    illustrates a perspective view of the rear side of the panel element  4  from  FIG.  1   . The rear side of the panel element  4  is identified in the figure by  11 . As is apparent when viewed together with  FIG.  1   , the panel element  4  has a main extension plane E which in the assembled state of the panel system  2  extends in the vertical direction H (cf. also  FIG.  1   ) and in the width direction B (cf. likewise  FIG.  1   ) of the cooking appliance  1 . 
     A first connecting element  12  and a second connecting element  13  are provided on the panel element  4 . In this case, the first connecting element  12  is configured in accordance with the exemplary embodiment as a rail. The rail  12  is produced by a double folded edge of the metal plate from which the panel element  4  is manufactured. The metal plate can be by way of example a steel or stainless steel metal plate. As an alternative, the panel element  4  can also be manufactured from plastic. In this case, the panel element  4  is produced as an injection molded part together with the double folded edge. The rail  12  extends along an upper longitudinal side  14  of the panel element  4 , said upper longitudinal side being provided in the vertical direction H. 
     Moreover, the panel element  4  comprises a single folded edge  15  which in relation to the vertical direction H extends along the upper longitudinal side  16  of the panel element  4 . The single folded edge  15  is manufactured in the same manner as the double folded edge as one piece with the panel element  4 . In a similar manner to the double folded edge, the single folded edge  15  is likewise produced from the metal blank that is used for manufacturing the panel element  4  (or injection molding), and especially by being bent out of the main extension plane E. Whereas the single folded edge  15  extends in a perpendicular manner to the main extension plane E, the double folded edge or rail  12  comprises two sections  17 ,  18 . The first section  17  extends likewise in a perpendicular manner with respect to the main extension plane E. The section  18 , which is in turn folded over with respect to the section  17 , extends in a plane parallel to the main extension plane E. 
     The second connecting element  13  is configured in the form of multiple cut-outs in the single fold edge  15 . The shape of the cut-outs can be by way of example circular, square, rectangular, round, oval or in any other shape. 
     Furthermore,  FIG.  2    illustrates through-going holes  19  for the rotary knob  6  and a rectangular slot  20  for the display  10 . The slot  20  can also be round, oval etc. The through-going holes  19  are provided with a circumferential indent  21 . Owing to the indent  21 , it is possible to forego a switch handle protector which reduces the risk of injury for the user and prevents the rotary knob scratching against the through-going hole  19  as the recessible rotary knob  6  is lowered into or moved out of said through-going hole. The indent  21  is produced by the metal blank that is used for manufacturing the panel element  4  (or in injection molding) being bent over circumferential and especially by being bent out of the main extension plane E. In this case, the bent over edge of the circumferential indent is round in order to reduce the risk of injury, in particular in the case of an actuation in order to move out the recessible rotary knob  6 . 
     In order to fix the panel element  4  in the width direction B to the carcass  3  (cf.  FIG.  1   ), it is possible to provide on the lower longitudinal side  16  by way of example tabs  22  with the aid of which the panel element  4  is screwed to the carcass  3 . 
       FIG.  3    illustrates the view from  FIG.  2   . Furthermore,  FIG.  3    illustrates an add-on piece in the form of a switch receptacle  23  for receiving one of the rotary knobs  6  (cf.  FIG.  1   ) in its recessed position.  FIG.  3    illustrates the switch receptacle  23  in its installed state. 
       FIGS.  4  to  9    illustrate the construction and the function of the switch receptacle  23  that is mentioned in conjunction with  FIG.  3   . The switch receptacle  23  has a base body  24  that comprises a first housing part  25  and a second housing part  26 .  FIGS.  4  to  6    illustrate the first housing part  25  with a first fastening element  27  of the switch receptacle  23  and  FIGS.  7  to  9    illustrate the second housing part  26  with a second fastening element  28  of the switch receptacle  23 . The first and second housing part  25 ,  26  are each in the form of a half shell. It is possible to use for example plastic or metal, such as for example steel, stainless steel or aluminum or a combination of plastic and metal, as a material for the first and second housing part  25 ,  26  and for the first and second fastening element  27 ,  28 . The first and second housing part  25 ,  26  and the first and second fastening element  27 ,  28  can be produced as an injection molded part. The second housing part  26  comprises multiple latching protrusions  29  that are configured on the outer side of the second housing part  26  (cf.  FIG.  7   ). The first housing part  25  comprises the same number of mating latches  30  as the number of latching protrusions  29  in the second housing part  26 . The mating latches  30  are arranged on an outer side of the first housing part  25  (cf.  FIG.  4   ). The first housing part  25  is joined to the second housing part  26 , in that the latching protrusions  29  latch with the mating latches  30 . 
     Furthermore,  FIG.  4    illustrates a guiding element  31 , which is configured by way of example as a rail, and a wedge  32  which are configured as one piece with the first housing part  25 . The wedge  32  is configured on the outer surface of the housing part  25 . The wedge  32  has a planar surface that is inclined with respect to a direction in which the add-on piece is assembled on the panel element  4  (in the present case also referred to as the “assembling direction M”). The assembling direction M is illustrated in  FIG.  10   . An angle of inclination a of the wedge  32 , which is illustrated in  FIG.  10   , can be by way of example between 15° and 45°. The rail  31  is arranged on the planar inclined surface of the wedge  32  that faces away from the base body  24 . The rail  31  is inclined as the wedge  32  at the same angle α. The cross sectional shape of the rail  31  is in the shape of a “T”. The rail  31  has at the foot of the “T” a surface by way of which the rail  31  is connected to the wedge  32  the inclined planar surface of the wedge  30 . The rail  31  has on an inclined planar surface that faces away from the first housing part  25  (roof of the “T”), two cut-outs  33   a ,  33   b . The shape of the cut-outs  33   a ,  33   b  can be by way of example circular, square, rectangular, round or oval. 
       FIG.  5    illustrates the first fastening element  27 . The first fastening element  27  is arranged on the rail  31  ( FIG.  4   ) in such a manner that it is displaceable in a linear manner in a guiding direction F ( FIG.  10   ) on said rail. The displacement direction of the first fastening element  27  is in this case at the same angle α as the rail  31  and the wedge  32  with respect to the assembling direction M. In this case, the rail  31  is used as a guiding rail for the first fastening element  27 . The first fastening element  27  has a mating guiding element  34  via which the first fastening element  27  is connected to the rail  31 . In another exemplary embodiment, the mating guiding element  34  can be arranged in lieu of the rail  31  on the surface of the wedge  32  that is facing away from the base body  24 . The rail  31  can be arranged for this purpose by way of example also in lieu of the mating guiding element  34  on the first fastening element  27 . The shape of the cross section of the mating guiding element  34  is preferably in the shape of a “C”. The mating guiding element  34  encompasses the rail  31  at its lateral end edges in the guiding direction F. The mating guiding element  34  and the rail  31  can also have other profiles, by way of example, the mating guiding element  34  can encompass the rail  31  inside and/or outside. The rail  31  can by way of example also encompass the mating guiding element  34  inside and/or outside. The first fastening element  27  is configured so as to come into engagement with the connecting element  12  and to fasten the base body  24  to the panel element  4 , as will be explained in more detail later. 
     The rail  31  is formed as one piece with the first housing part  25 . The mating guiding element  34  is formed as one piece with the first fastening element  27 . The rail  31  can be formed by way of example in lieu of the mating guiding element  34  as one piece with the first fastening element  27 . The mating guiding element  34  can be formed by way of example in lieu of the rail  31  as one piece with the first housing part  25 . 
       FIG.  6    illustrates the view of the rear side of the first fastening element  27 . In order to come into engagement with one of the two cut-outs  33   a ,  33   b , the first fastening element  27  has a latching protrusion  35  on the planar surface via which the first fastening element  27  is connected to the rail  31 . The shape of the latching protrusion  35  corresponds in this case to the shape of the cut-outs  33   a ,  33   b.    
       FIG.  7    illustrates the second housing part  26  that comprises a guiding element  36  and an inclined section  37  (also referred to here as a “further element”). The second housing part  26 , the guiding element  36  and the inclined section  37  are configured as one piece. The guiding element  36  and the inclined section  37  can be produced by way of example from plastic or metal, such as for example steel, stainless steel or aluminum. The guiding element  36  is configured on the surface of the second housing part  26  and has two angled sections whose cross section is an “L-shape”. The “L-foot” of the respective section faces in this case outwards away from the base body  24 . The inclined section  37  is configured with thin walls, bent at one end and at this end connected to the outer surface of the second housing part  26  and arranged between the angled sections of the guiding element  36 . The inclined section  37  is likewise inclined in the same manner as the wedge  32  with respect to the assembling direction M. The angle of inclination of the inclined sections  37  can be in this case flatter than the angle of inclination a of the wedge  32 , in other words for example only 10°-20°. As a result, the distance traveled by the fastening element  28  in the opposite direction to the vertical direction H in order to come into engagement with the connecting element  13  is shorter in comparison to the distance traveled by the fastening element  27  in the vertical direction H in order to come into engagement with the rail  12 . As a result, less installation space is advantageously required. 
     The guiding element  36  is inclined at the same angle as the inclined section  37  with respect to the assembling direction M. Furthermore, the inclined section  37  has two cut-outs  38   a ,  38   b . The shape of the cut-outs  38   a ,  38   b  can be by way of example circular, square, rectangular, round, oval or in another shape. 
       FIG.  8    illustrates the second fastening element  28  that is configured so as to come into engagement with the connecting element  13  and to fasten the base body  24  to the panel element  4 , as will be explained in more detail later. The second fastening element  28  has an inclined surface on which a mating guiding element  39  is provided. The shape of the cross section of the mating guiding element  39  is preferably in the shape of a “C”. The mating guiding element  39  encompasses the guiding element  36  on its lateral end edges in the guiding direction. The mating guiding element  39  and the guiding element  36  can also have other profiles, by way of example the mating guiding element  39  can encompass the guiding element  36  inside and/or outside. The guiding element  36  can by way of example also encompass the mating guiding element  39  inside and/or outside. The displacement direction of the second fastening element  28  is at the same angle as the angle of inclination of the guiding element  36  and of the inclined section  37  with respect to the assembling direction M. The guiding element  36  is used as a guiding rail for the second fastening element  28 . 
     The profile of the mating guiding element  39  corresponds in this case to the profile of the guiding element  36 . The mating guiding element  39  can by way of example also be arranged in lieu of the guiding element  36  on the surface of the inclined section  37  that is facing away from the base body  24 . The guiding element  36  can be arranged for this purpose by way of example in lieu of the mating guiding element  39  on the second fastening element  28 . The mating guiding element  39  and the guiding element  36  can also have other profiles, by way of example the mating guiding element  39  can encompass the guiding element  36  inside and/or outside. The guiding element  36  can by way of example also encompass the mating guiding element  34  inside and/or outside. 
     The guiding element  36  is formed as one piece with the second housing part  26 . The mating guiding element  39  is formed as one piece with the second fastening element  28 . The guiding element  36  can be formed in an alternative embodiment by way of example in lieu of the mating guiding element  39  as one piece with the second fastening element  28 . The mating guiding element  39  can be formed by way of example in lieu of the guiding element  36  as one piece with the second housing part  26 . The side of the second fastening element  28  that is remote from the mating guiding element  39  has two latching protrusions  40 . 
       FIG.  9    illustrates the view of the rear side of the second fastening element  28 . A further latching protrusion  41  is attached to the inner side of said fastening element and said further latching protrusion comes into engagement with one of the two cut-outs  38   a ,  38   b . The shape of the latching protrusion  41  corresponds in this case to the shape of the cut-outs  38   a ,  38   b.    
     Prior to the switch receptacle  23  being mounted on the panel element  4 , the first and the second fastening element  27 ,  28  are attached to the base body  24  in a pre-assembled state which is described below. The first fastening element  27  is pushed onto the rail  31  so far until the latching protrusion  35  latches in the cut-out  33   a  that is arranged in the assembling direction M closer to the panel element  4 . If the latching protrusion  35  latches in the cut-out  33   a , the first fastening element  27  is located in a first position with respect to the base body  24 . The latching protrusion  35  latches in a releasable manner in the cut-out  33   a  in such a manner that it is only possible for the first fastening element  27  to move away from the base body  24  in the guiding direction F. In contrast, a movement back of the first fastening element  27  in the opposite direction to the guiding direction F is blocked. 
     In a similar manner thereto, the second fastening element  28  is pushed onto the guiding element  36 . If the latching protrusion  41  latches in the cut-out  38   a , which is arranged closer to the panel element  4  in the assembling direction M, the second fastening element  28  is located in a first position with respect to the base body  24 . The latching protrusion  41  latches in a releasable manner in the cut-out  38   a  in such a manner that the second fastening element  28  can only move away from the base body  24  in the guiding direction F. In contrast, a movement back of the second fastening element  28  in the opposite direction to the guiding direction F is blocked. As a result, the first and second fastening element  27 ,  28  are prevented from falling off the base body  24 , in particular during the assembling. Furthermore, it is not necessary for the first and second fastening element  27 ,  28  to be held by a worker or robot during the assembling. As a result, the assembling of the switch receptacle  23  is simplified. 
     Starting from the pre-assembled state,  FIGS.  10  to  12    illustrate now the assembling of the switch receptacle  23  on the panel element  4 .  FIG.  10    illustrates the switch receptacle  23  with the first and second fastening element  27 ,  28  in the pre-assembled state together with the panel element  4  in a perpendicular manner with respect to the panel plane E. In this case, the first and second fastening element  27 ,  28  protrude beyond the base body  24  in the assembling direction M (cf.  FIG.  10   ). For the assembling, the base body  24  is moved in the assembling direction M in a perpendicular manner with respect to the panel plane E (cf.  FIG.  3   ), and especially exclusively in this direction. 
     After the first and second fastening element  27 ,  28  come into contact with the panel element  4  (cf.  FIG.  11   ), the first fastening element  27  is moved in the illustrated direction upwards (corresponding to the vertical direction H) and the second fastening element  28  moves in the illustrated direction downwards (corresponding to a direction opposite to the vertical direction H) while the base body  24  is moved simultaneously towards the panel element  4 . The first fastening element  27  moves along the rail  31  in the guiding direction F away from the base body  24  (also referred to in the present case as the “movement away”). In this case, the latching protrusion  35  leaves the cut-out  33   a  in the first position. The second fastening element  28  moves along the guiding element  36  in the guiding direction away from the base body  24 . In this case, the latching protrusion  41  leaves the cut-out  38   a  in the first position. If the base body  24  moves further in the assembling direction M towards the panel element  4 , the first fastening element  27  moves along the rail  31  so far until the latching protrusion  35  latches in the cut-out  33   b  in the second position, which is further away in the assembling direction M from the cut-out  33   b  in the first position. The second fastening element  28  moves along the guiding element  36  so far until the latching protrusion  41  latches in the cut-out  38   b  in a second position, which is further away in the assembling direction M from the cut-out  38   b  in the first position. Simultaneously, the first fastening element  27  comes into engagement with the double folded edge or with the pocket, which is formed by said double folded edge, is open in the downwards direction (against the vertical direction) and in which the first fastening element  27  engages in the vertical direction H. The latching protrusions  40  of the second fastening element  28  come into engagement with the cut-out  13  (cf.  FIG.  12   ). The profile of the double folded edge corresponds to the profile of the first fastening element  27 , with the result that said first fastening element can only be displaced in the extension direction E. The latching protrusions  40  of the second fastening element  28  engage in the cut-out  13  in such a manner that it is prevented from moving out of the cut-out  13 . Accordingly, the switch receptacle  23  is fixed in the state illustrated in  FIG.  13    in six degrees of freedom (also referred to in the present case as the “assembled state” 
       FIG.  13    illustrates a sectional view of the switch receptacle  23  that is assembled on the panel element  4  with a recessed rotary knob  6 . 
     The inclined section  37  protrudes beyond the second fastening element  28 , as is illustrated in  FIG.  13   , and is accessible to a user. The inclined section  37  is configured in an elastic bendable manner so that as said inclined section is being bent towards the base body  24 , the latching protrusion  41  of the second fastening element  28  becomes disengaged from the cut-out  38   b . By way of a simultaneous movement of the base body  24  in the opposite direction to the assembling direction M, the base body  24  can the second fastening element  28  moves back in the opposite direction to the guiding direction F (the movement in this direction is also referred to in the present case as the “movement back” and is identified in  FIG.  10    by “Z”) and can be dismantled from the panel element  4 . 
     In a further embodiment, in lieu of the wedge  32 , an inclined section (not illustrated) is arranged, which is configured in an elastic bendable manner so that as said inclined section is being bent towards the base body  24  the latching protrusion  35  of the first fastening element  27  becomes disengaged from the cut-out  33   b . As a result, the latching protrusions  35  and  41  can be simultaneously released from the cut-outs  33   b    38   b  and the first and second fastening element  27 ,  28  can be simultaneously dismantled. 
     Advantageously, the connecting elements  12 ,  13  described here and the first and second fastening element  27 ,  28  are all arranged on the rear side  11  of the panel element  4  so that these are not visible to the user who is operating the cooking appliance  1  in the proper manner. In addition, as is apparent in  FIG.  1   , this consequently creates a smooth closed surface of the panel element  4 . 
     Fundamentally, the assembling described here of the switch receptacle  23  and the pre-assembling of the first and second fastening element  27 ,  28  on the add-on piece  23  can be performed manually or automatically. In lieu of or in addition to the connecting elements  12 ,  13  described here and the first and second fastening element  27 ,  28 , it is also possible to use non-releasable types of connections, for example clinching. 
     In the present description, the add-on piece is described using the example of a switch receptacle  23 . Further add-on pieces can be a WLAN module, a sound module, a display  10  or the like. 
     Although the present invention has been described with the aid of exemplary embodiments, it can be modified in numerous ways.