Patent Publication Number: US-9907123-B2

Title: Microwave sealing device of an opening for a rotating shaft

Description:
The present invention relates to a microwave sealing device of an opening for a rotating shaft or axle. Further, the present invention relates to a microwave oven with at least one sealing device of an opening for a rotating shaft  10  or axle. 
     Microwave ovens generate strong electromagnetic or magnetic fields in order to heat food stuff and beverages. However, such strong electromagnetic fields are a potential threat to the health of the operator, if said electromagnetic fields or parts of them leave the cavity of the microwave oven. The openings of the cavity are very critical parts. 
     In particular, the opening for a rotating shaft or axle, e.g. for a hot air fan, is a critical point. Due to the axial movement caused by the fast rotation of the shaft, the diameter of the opening in the wall is often bigger than the diameter of the enclosed rotating object. It is necessary to seal such openings. 
     Known solutions for sealing such an opening tend to be very bulky or are prone to mechanical tolerances with respect to the leakage. Further, the heat transfer due to the direct metal contact between the hot cavity wall and the sealing can cause problems on the electric components. For example, the electric drives of the fan, the turn table or the motor of other rotating components. 
     It is the object of the present invention to provide a microwave sealing device of an opening for a rotating shaft or axle, which prevents an excess heat transfer from the cavity wall to the electric components. 
     This object is achieved by the microwave sealing device according to claim  1 . 
     According to the present invention
         the sealing device is provided for enclosing a section of the shaft or axle,   the sealing device includes a front panel and a basis part,   the front panel is formed as a plane disk and comprises a central hole in its centre and a plurality of cuts,   the basis part is formed as a hollow part with a peripheral wall and two opposing face sides,   at least one of the two opposing face sides of the basis part is open,   the basis part comprises a plurality of cuts in the peripheral wall, and   the front panel is attached at the open face side or at one of the two open face sides, respectively, of the basis part.       

     The core of the present invention is the front panel with the cuts and the corresponding basis part formed as a hollow part. Both are provided for enclosing a section of the shaft or axle. The shape of the basis part may be arbitrary. The inventive sealing device may be arranged close at the outer side of the cavity wall without any mechanical and electric contact between the sealing device and the cavity wall. Thus, there is no heat transfer from the cavity wall to electric devices. 
     According to the preferred embodiment of the present invention the cut of the front panel is set forth by a corresponding cut of the basis part. In particular, the cut of the front panel and the corresponding cut of the basis part are substantially orthogonal to each other. 
     For the application with the microwave oven the front panel may be provided to be arranged parallel to the opening. 
     According to a first embodiment of the present invention the front panel covers that open face side of the basis part, at which the front panel is attached. In particular, the diameter of the front panel is substantially equal to the diameter of that open face side, at which the front panel is attached. 
     According to a second embodiment of the present invention that open face side of the basis part, at which the front panel is attached, covers the central hole of the front panel. In particular, the diameter of that open face side of the basis part, at which the front panel is attached, is substantially equal to the diameter of the central hole of the front panel. 
     For example, the cuts of the front panel may be formed as slots, circular holes, elliptical holes and/or rectangular holes. 
     In a similar way, the cuts of the basis part are formed as slots, circular holes, elliptical holes and/or rectangular holes. 
     Preferably, the front panel may comprise a plurality of sectors separated by slots. 
     Further, the sealing device may be formed as a single piece part. 
     The sealing device is made of at least one electrically conductive material. In particular, the sealing device is made of metal. 
     The object of the present invention is further achieved by a microwave oven with at least one sealing device of an opening for a rotating shaft or axle, wherein the microwave oven includes the sealing device as described above. 
    
    
     
       The invention will be explained in more detail below by means of an exemplary embodiment. Reference is thereby made to the drawings, wherein 
         FIG. 1  shows a schematic perspective view of a microwave sealing device of an opening for a rotating shaft or axle according to a first embodiment of the present invention, 
         FIG. 2  shows a schematic perspective view of the microwave sealing device of the opening for the rotating shaft or axle according to a second embodiment of the present invention, 
         FIG. 3  shows a schematic side view of an application of the microwave sealing device according to the first embodiment of the present invention, 
         FIG. 4  shows a schematic top view of a front panel of the sealing device according to the first embodiment of the present invention, 
         FIG. 5  shows a schematic top view of another example of the front panel of the sealing device according to the first embodiment of the present invention, 
         FIG. 6  shows a schematic top view of further example of the front panel of the sealing device according to the first embodiment of the present invention, 
         FIG. 7  shows a schematic front view of the front panel of the sealing device according to a third embodiment of the present invention, and 
         FIG. 8  shows a schematic front view of a basis part of the sealing device according to the third embodiment of the present invention. 
     
    
    
       FIG. 1  shows a schematic perspective view of a microwave sealing device  10  of an opening for a rotating shaft or axle according to a first embodiment of the present invention. The microwave sealing device  10  comprises a front panel  12  and a basis part  14 . 
     The front panel  12  is formed as a circular disk and comprises a central hole  16  in its centre. The front panel  12  is subdivided into a number of sectors  18 . In this example the front panel  12  includes eight equal sectors  18 . The sectors  18  are separated by slots  20 . 
     The basis part  14  is formed as a cylinder barrel. The front panel  12  covers one of the two open face sides of the basis part  14 . The diameter of the front panel  12  is about equal to the diameter of the basis part  14 . The basis part  14  comprises a number of slots  22  extending parallel to the longitudinal axis of said basis part  14 . The slots  22  extend over about the half length of the basis part  14 . Each slot  22  of the basis part  14  corresponds with one of slot  20  of the front panel  12 . Each slot  20  of the front panel  12  is set forth by the corresponding slot  22  of the basis part  14 . The corresponding slots  20  and  22  extend perpendicular to each other. 
     The microwave sealing device  10  is made of an electrically conductive material, in particular made of metal. 
     The microwave sealing device  10  is provided for sealing the opening for a rotating shaft or axle. Thereby, the shaft or axle extends along the central longitudinal axis of the basis part  14 . Further, it is provided, that the shaft or axle penetrates the front panel  12  through the central hole  16  and the basis part  14 . 
       FIG. 2  shows a schematic perspective view of a microwave sealing device  30  of an opening for a rotating shaft  26  or axle according to a second embodiment of the present invention. The microwave sealing device  30  comprises a front panel  32  and a basis part  34 . 
     The front panel  32  is formed as a circular disk with a circular central hole  36  in its centre. The front panel  32  is subdivided into a number of sectors  38 . In this example the front panel  12  includes eight equal sectors  38 . The sectors  38  are separated by slots  40 . 
     The basis part  34  is formed as a cylinder barrel. The front panel  32  encloses one of the two open face sides of the basis part  34 . The inner diameter of the front panel  32  corresponds with the central hole  16  and is about equal to the diameter of the basis part  14 . The basis part  14  comprises a number of slots  42  extending parallel to the longitudinal axis of said basis part  34 . The slots  42  extend over about the half length of the basis part  34 . Each slot  42  of the basis part  34  corresponds with one of slot  40  of the front panel  32 . Each slot  40  of the front panel  32  is set forth by the corresponding slot  42  of the basis part  34 . The corresponding slots  40  and  42  extend perpendicular to each other. 
     The microwave sealing device  30  is also made of an electrically conductive material, in particular made of metal. 
     The microwave sealing device  30  is provided for sealing the opening for the rotating shaft or axle. Thereby, the shaft  26  or axle extends along the central longitudinal axis of the basis part  34 . Further, the shaft or axle penetrates the front panel  32  through the central hole  36  as well as the basis part  34 . 
       FIG. 3  shows a schematic side view of an application of the microwave sealing device  10  according to the first embodiment of the present invention. 
     The microwave sealing device  10  is arranged besides an opening in a cavity wall  24  of a microwave oven. The sealing device  10  is arranged on the outside of the cavity wall  24 . The shaft  26  penetrates the opening in the cavity wall  24  and the sealing device  10 . The shaft  26  extends perpendicular to the plane of the cavity wall  26 . Further, a motor  28  is arranged on the outside of the cavity wall  24 . The sealing device  10  is arranged between the motor  28  and the cavity wall  24 . The sealing device  10  is attached at the motor  28 . 
     The sealing device  10  is arranged in such a way that there is no mechanical and electric contact between the motor  28  and the cavity wall  24 . The sealing device  10  is attached at the motor  28 , but not at the cavity wall  24 . Thus, there is no substantial heat transfer from the cavity wall  24  to the motor  28 . 
       FIG. 4  shows a schematic top view of a front panel  12  of the sealing device  10  according to the first embodiment of the present invention.  FIG. 4  illustrates the arrangement of the sectors  18  and the slots  20 . The front panel  12  is formed as a circular disk. 
       FIG. 5  shows a schematic top view of another example of the front panel  12  of the sealing device  10  according to the first embodiment of the present invention. The front panel  12  is formed in a similar way as in  FIG. 4 , wherein two additional elements  44  are arranged at the outer portion of the front panel  12 . Said elements  44  extend perpendicular to the plane of the front panel  12 . 
       FIG. 6  shows a schematic top view of further example of the front panel  12  of the sealing device  10  according to the first embodiment of the present invention. The front panel  12  is formed in a similar way as in  FIG. 4 , wherein two additional L-shaped elements  46  are arranged at the outer portion of the front panel  12 . 
     The elements  44  and  46  may act as brackets for fixing the front panel  12  onto the basis part  14 . 
       FIG. 7  shows a schematic front view of a front panel  52  of a sealing device  50  according to a third embodiment of the present invention. The front panel  52  is formed as a circular disk with a circular central hole  56  in its centre. The diameter of said circular hole  56  is about one third of the diameter of the front panel  52 . The front panel  52  comprises four slots  58  and four holes  60  alternately arranged along a circumferential direction. The four slots  58  extend in a radial direction of the front panel  52 . 
       FIG. 8  shows a schematic front view of a basis part  54  of the sealing device  50  according to the third embodiment of the present invention. The basis part  54  has a rectangular cross section. The basis part  54  comprises several cuts  62 . In this example, the basis part  54  comprises seven cuts  62 . The cuts  62  may be formed as slots, circular holes, elliptical holes and/or rectangular holes, for example. 
     In the above described embodiments there is no mechanical and electric contact between the cavity wall  24  around the opening and the sealing devices  10 ,  30  and  50 . 
     The sealing device  10 ,  30  and  50  is made of metal, expanded metal and/or any materials which can be metallised, in particular polymers or ceramics. Further, the sealing device  10 , and  50  can be made of materials with electrically conductive fillings or nano technologic materials. The sealing device  10 , and  50  may be a single piece part. 
     In general, the basis part  14 ,  34  and  54  is a hollow part with an arbitrary shape. Preferably, the basis part  14 ,  34  and  54  is a hollow cylinder or a hollow part with a rectangular or elliptical cross section. 
     The shape of the front panel  12 ,  32  and  52  can differ from the shape of the basis Part  14 ,  34  and  54 . The shapes of the holes  60  in the front panel  12 ,  32  and  52  are arbitrary, for example circular, elliptical or rectangular. The shapes of the slots  20 ,  22 ,  40 ,  42  and  58  are arbitrary. Preferably, the shapes of the slots  20 ,  22 ,  40 ,  42  and  58  have uniform widths, continuously decreasing or increasing widths or stepped widths. For example, at the angle formed by the front panel  12 ,  32  and  52  and the basis part  14 ,  34  and  54  the width of the slots  20 ,  22 ,  40 ,  42  and  58  are stepped. 
     Alternatively, the slots  20 ,  22 ,  40 ,  42  and  58  can be partially or completely replaced by embossed grooves. Preferably, the slots  20 ,  22 ,  40 ,  42  and  58  and modifications of them, respectively, are aligned, e.g. orthogonal to the edges of the front plate or parallel to the shaft  26 . 
     The sealing device  10 ,  30  and  50  can be modified in order to seal removable subjects, such as a turn spit. 
     In the above described embodiments the sealing devices  10 ,  30  and  50  are static parts of the microwave oven. Alternatively, the sealing devices  10 ,  30  and  50  can be rotatable. In this case the front panel  12 ,  32  and  52  may not have any mechanical or electric contact to that part, which has to be sealed. 
     LIST OF REFERENCE NUMERALS 
     
         
           10  sealing device 
           12  front panel 
           14  basis part 
           16  central hole 
           18  sector 
           20  slot of the front panel 
           22  slot of the basis part 
           24  cavity wall 
           26  shaft 
           28  motor 
           30  sealing device 
           32  front panel 
           34  basis part 
           36  central hole 
           38  sector 
           40  slot of the front panel 
           42  slot of the basis part 
           44  element 
           46  element 
           50  sealing device 
           52  front panel 
           54  basis part 
           56  central hole 
           58  slot of the front panel 
           60  hole of the front panel 
           62  cut of the basis part