Patent Publication Number: US-11039509-B2

Title: Oven door for a microwave oven

Description:
The present invention relates to an oven door for a microwave oven or a cooking oven with microwave heating functions. Further, the present invention relates to a microwave oven or a cooking oven with microwave heating functions. 
     A microwave oven generates electromagnetic fields for heating food and beverages in the oven cavity. Usually, the oven door of the microwave oven comprises at least an inner glass panel and an outer glass panel. The oven door of the microwave oven is partially transparent, so that the user is able to monitor the progress of the cooking process in the oven cavity. Compared to an oven door of a cooking oven without microwave heating functions, the transparent area of the oven door for the microwave oven is relative small, since a wave choke device is arranged within the door frame. Said wave choke device blocks the gap between the oven door and a front frame of the microwave oven against the electromagnetic field inside the oven cavity. The wave choke device is covered by a door cover made of non-metallic parts. Preferably, said door cover is made of high temperature resistant polymers. 
     Usually, the inner glass panel and the door frame are connected by a glue joint consisting of silicone. The temperature resistance of silicone is lower than 200° C., while the temperature resistance of the door frame and glass panel is higher. Further, the glue joint is positioned in an area of critical temperatures, due to the extension of the wave choke device. Thus, the glue joint is thermally stressed, so that failures in the oven door may occur. For example, condensate may infiltrate into the interior of the oven door. Further, the inner glass panel may be lost. 
       FIG. 6  illustrates a schematic sectional perspective view of the inner part  10  of the oven door for the microwave oven according to the prior art. The inner part  10  of the oven door includes a door cover  12  and an inner glass panel  14 . The door cover  12  encloses the inner glass panel  14 . The inner glass panel  14  faces the oven cavity of the microwave oven in the closed state of the oven door, wherein a gasket is arranged between the inner glass panel  14  and the oven cavity. The welded system consisting of glass panel  14  and door cover  12  includes an L-shaped cross-section, wherein an inner leg of said L-shaped cross-section extends parallel to the plane of the inner glass panel  14 . An outer leg of the L-shaped cross-section encloses the inner leg, is arranged perpendicular to said inner leg and extends outwards from the inner leg. The inner leg of the door cover  12  and an outer portion of an inner surface of the inner glass panel  14  overlap. In an overlap area of the inner leg of the door cover  12  and the inner glass panel  14 , said door cover  12  and inner glass panel  14  are glued together. A glue joint  18  is formed in the overlap area of the inner leg of the door cover  12  and the inner glass panel  14 . The outer portion of the inner surface of the inner glass panel  14  is connected to an outer side of the inner leg of the door cover  12  by the glue joint  18 . 
     It is an object of the present invention to provide an oven door for a microwave oven, wherein the connection between the door cover and at least one glass panel is improved. 
     According to the present invention an oven door for a microwave oven or a cooking oven with microwave heating functions is provided, wherein:
         the oven door comprises at least one door cover and at least one glass panel,   the door cover and the inner glass panel form an inner part of the oven door,   the door cover encloses the glass panel,   the door cover and the glass panel are connected by a welded joint,   the welded joint is formed in an overlap area of the door cover and the glass panel, and   the welded joint ( 16 ) forms an elongated path.       

     The core of the present invention is the welded joint between the door cover and the glass panel. The welded joint provides a high temperature resistance and a tight connection between the door cover and the inner glass panel. Further, the welded joint provides an improved design of the inner side of the oven door. 
     In particular, the welded joint forms a closed elongated path or at least one open elongated path, wherein preferably the door cover encloses completely the glass panel. The door cover enclosing completely the glass panel contributes to the tight connection between the door cover and the inner glass panel. 
     Further, the glass panel may be an inner glass panel and faces an oven cavity in a closed state of the oven door, wherein preferably a gasket is provided between said inner glass panel and oven cavity. The inner glass panel is in a high temperature area. 
     Moreover, the door cover may include at least one dielectric material, wherein preferably at least a part of the door cover is made of polymers, or the door cover is made of metal. 
     According to one embodiment of the present invention, the overlap area is formed by an outer portion of a surface of the glass panel and a surface at an inner portion of the door cover, wherein the surface at the inner portion of the door cover extends parallel to the plane of the glass panel, and wherein preferably the inner portion of the door cover faces the oven cavity in the closed state of the oven door, while the welded joint at the inner portion of the door cover faces away from the oven cavity in the closed state of the oven door. 
     Further, the door cover may include an L-shaped cross-section, wherein a first leg of the L-shaped cross-section may form the inner portion of the cross-section of the door cover, while a second leg of the L-shaped cross-section may enclose the first leg and may extend away from the oven cavity in the closed state of the oven door. 
     According to another example, the first leg of the L-shaped cross-section of the door cover is made of the dielectric material, while the second leg of the L-shaped cross-section of said door cover is made of metal. Preferably, the first leg of the L-shaped cross-section of the door cover is made of polymers. 
     In particular, the corner of the L-shaped cross-section of the door cover is made of the dielectric material, preferably of polymers. 
     According to another embodiment of the present invention, the overlap area is formed by an inner side of the door cover and a circumferential side of the inner glass panel, so that the circumferential side of the inner glass panel is connected to the inner side of the door cover by the welded joint. 
     Additionally, the oven door may comprise an outer glass panel attached or attachable to an outer side of the door cover, wherein said outer side of the door cover faces away from the oven cavity. 
     Preferably, the outer glass panel is glued to door columns, wherein preferably the door cover is fixed to said door columns. 
     Alternatively, the oven door may comprise a further door cover glued to the outer glass panel, wherein preferably the door cover is fixed to said further door cover. 
     Moreover, the oven door may comprise at least one intermediate glass panel arranged between the inner glass panel and the outer glass panel. 
     Additionally, the oven door comprises a wave choke device  24  ( FIG. 4 ) enclosing at least one glass panel and covered by the door cover and/or the further door cover. The wave choke device is provided for blocking a gap formed between the oven door and the microwave oven against the electromagnetic field inside the oven cavity. 
     At last, the present invention relates to a microwave oven or a cooking oven with microwave heating functions, wherein the microwave oven or cooking oven with microwave heating functions, respectively, comprises at least one oven door mentioned above. 
     Novel and inventive features of the present invention are set forth in the appended claims. 
    
    
     
       The present invention will be described in further detail with reference to the drawings, in which 
         FIG. 1  illustrates a schematic view at an outer side of an inner part of an oven door for a microwave oven according to a first embodiment of the present invention, 
         FIG. 2  illustrates a schematic view at an inner side of the inner part of the oven door for the microwave oven according to the first embodiment of the present invention, 
         FIG. 3  illustrates a schematic sectional perspective view of the inner part of the oven door for the microwave oven according to the first embodiment of the present invention, 
         FIG. 4  illustrates a schematic sectional view of the inner part of the oven door for the microwave oven according to a second embodiment of the present invention, 
         FIG. 5  illustrates a schematic sectional view of the inner part of the oven door for the microwave oven according to a third embodiment of the present invention, and 
         FIG. 6  illustrates a schematic sectional perspective view of the inner part of the oven door for the microwave oven according to the prior art. 
     
    
    
       FIG. 1  illustrates a schematic view at an outer side of an inner part  10  of the oven door for a microwave oven according to a first embodiment of the present invention. The outer side of the inner part  10  of the oven door faces away from an oven cavity in a closed state of said door. The inner part  10  of the oven door is that part facing an oven cavity of the microwave oven in a closed state of the oven door. The term “inner” relates to the direction to the oven cavity of the microwave oven in a closed state of the oven door. In contrast, the term “outer” relates to the direction away from the oven cavity of the microwave oven and to the front of said microwave oven in the closed state of the oven door. 
     The inner part  10  of the oven door includes a door cover  12  and an inner glass panel  14 . The door cover  12  encloses the inner glass panel  14 . The inner glass panel  14  faces the oven cavity of the microwave oven in the closed state of the oven door, wherein a gasket is provided between the inner glass panel  14  and the oven cavity. The gasket touches the inner glass panel  14  in the closed state of the oven door. The gasket is made of silicone or mesh. Mesh is suitable for pyrolytic ovens. In this example, the door cover  12  has an L-shaped cross-section. An inner leg of said L-shaped cross-section extends parallel to the plane of the inner glass panel  14 . An outer leg of the L-shaped cross-section encloses the inner leg, is arranged perpendicular to said inner leg and extends outwards from the inner leg. 
     The inner leg of the door cover  12  and an outer portion of an inner surface of the inner glass panel  14  overlap. In an overlap area of the inner leg of the door cover  12  and the inner glass panel  14 , said door cover  12  and inner glass panel  14  are welded together. Preferably, the door cover  12  is made of plastics. In particular, the door cover  12  is made of polymers. 
       FIG. 2  illustrates a schematic front view of the inner part  10  of the oven door for the microwave oven according to the first embodiment of the present invention. The inner side of the inner part  10  of the oven door faces the oven cavity in the closed state of said door.  FIG. 2  clarifies the connection between the door cover  12  and the inner glass panel  14 . 
     A welded joint  16  is formed in the overlap area between the inner leg of the door cover  12  and the inner glass panel  14 . The door cover  12  and the inner glass panel  14  are welded together. The welded joint  16  provides a high temperature resistance. Further, the welded joint  16  provides a tight connection between the door cover  12  and the inner glass panel  14 . Moreover, the welded joint  16  provides an improved design of the inner part  10  of the oven door. 
       FIG. 3  illustrates a schematic sectional perspective view of the inner part  10  of the oven door for the microwave oven according to the first embodiment of the present invention. The inner leg of the door cover  12  and the outer portion of the inner surface of the inner glass panel  14  overlap.  FIG. 3  clarifies the arrangement of the welded joint  16  between the door cover  12  and the inner glass panel  14 . 
     The welded joint  16  is formed in the overlap area of the inner leg of the door cover  12  and the inner glass panel  14 . The outer portion of the inner surface of the inner glass panel  14  is connected to an outer side of the inner leg of the door cover  12  by the welded joint  16 . The welded joint  16  allows the high temperature resistance and the tight connection between the door cover  12  and the inner glass panel  14 . Moreover, the welded joint  16  provides an improved design of the inner part  10  of the oven door. 
     The door cover  12  has the L-shaped cross-section. The inner leg of said L-shaped cross-section extends parallel to the plane of the inner glass panel  14 , while the outer leg of the L-shaped cross-section encloses the inner leg. The outer leg is arranged perpendicular to the inner leg and extends outwards from the inner leg. For example, the door cover  12  is made of dielectric material, preferably of polymers. Alternatively, the inner leg of the door cover  12  is made of dielectric material, while the outer leg of the door cover  12  may be made of metal, wherein the corner of the L-shaped cross-section of the door cover  12  is made of dielectric material. 
     An outer glass panel  20  ( FIG. 4 ) of the oven door is attached or attachable to the door cover  12  by different ways. For example, the outer glass panel is welded to a further door cover, wherein said further door cover is permanently or removably connected to the door cover  12 . In this case, the door cover  12  may form an inner door cover, while the further door cover may form an outer door cover. Further, the outer glass panel may be directly connected to the door cover  12  by a further welded joint or by any other connection. Moreover, the outer glass panel may include door columns welded or glued onto the inner surface of the outer glass panel, wherein said door columns are permanently or removably connected to the door cover  12 . 
     An intermediate layer  22   FIG. 4  may be arranged between the inner glass panel  14  and the outer glass panel  20 . For example, the intermediate layer is formed by metallization of the outer surface of the inner glass panel  14 . Further, the intermediate layer may be a separate panel and welded to the door cover  12 . 
     Further, at least one metal side frame may be welded to the door cover  12 , wherein said metal side frame supports the outer glass panel, the intermediate layer and/or further glass panels. 
       FIG. 4  illustrates a schematic sectional view of the inner part  10  of the oven door for the microwave oven according to a second embodiment of the present invention. 
     The inner part  10  of the oven door includes the door cover  12  and the inner glass panel  14 . The door cover  12  encloses the inner glass panel  14 . The inner glass panel  14  faces the oven cavity of the microwave oven in the closed state of the oven door. 
     Preferably, the gasket is provided between the inner glass panel  14  and the oven cavity. The gasket touches the inner glass panel  14  in the closed state of the oven door. The gasket is made of silicone or mesh. Mesh is suitable for pyrolytic ovens. 
     In this embodiment, the door cover  12  has an I-shaped cross-section. The I-shaped cross-section of the door cover  12  extends perpendicular to the plane of the inner glass panel  14 . 
     The welded joint  16  is formed in the overlap area of the inner side of the door cover  12  and the circumferential side of the inner glass panel  14 . The circumferential side of the inner glass panel  14  is connected to the inner side of the door cover  12  by the welded joint  16 . The welded joint  16  allows the high temperature resistance and the tight connection between the door cover  12  and the inner glass panel  14 . Moreover, the welded joint  16  provides an improved design of the inner part  10  of the oven door. 
     For the purpose of clarity, the welded joint  16  represented in  FIG. 4  is bigger than the real welded joint  16 . In practice, the welded joint  16  is smaller than the representation in  FIG. 4 . 
     In this embodiment, the door cover  12  is made of a dielectric material. For example, the door cover  12  is made of plastics. In particular, the door cover  12  is made of polymers. 
       FIG. 5  illustrates a schematic sectional view of the inner part  10  of the oven door for the microwave oven according to a third embodiment of the present invention. The third embodiment has similar geometric properties as the second embodiment of the present invention. 
     The inner part  10  of the oven door includes the door cover  12  and the inner glass panel  14 , wherein the door cover  12  encloses the inner glass panel  14 . The inner glass panel  14  faces the oven cavity of the microwave oven in the closed state of the oven door. 
     Preferably, the gasket is provided between the inner glass panel  14  and the oven cavity, wherein the gasket touches the inner glass panel  14  in the closed state of the oven door. The gasket may be made of silicone or mesh. Mesh is suitable for pyrolytic ovens. 
     Also in this embodiment, the door cover  12  has the I-shaped cross-section, wherein said I-shaped cross-section of the door cover  12  extends perpendicular to the plane of the inner glass panel  14 . 
     The welded joint  16  is formed in the overlap area of the inner side of the door cover  12  and the circumferential side of the inner glass panel  14 . The circumferential side of the inner glass panel  14  is connected to the inner side of the door cover  12  by the welded joint  16 . The welded joint  16  allows the high temperature resistance and the tight connection between the door cover  12  and the inner glass panel  14 . Moreover, the welded joint  16  provides an improved design of the inner part  10  of the oven door. 
     For the purpose of clarity, the welded joint  16  represented in  FIG. 5  is bigger than the real welded joint  16 . In practice, the welded joint  16  is smaller than the representation in  FIG. 5 . 
     In the third embodiment, the door cover  12  is made of metal. For example, the door cover  12  is made of aluminium or stainless steel. 
     In general, the door cover  12  according to the present invention may have an arbitrary shape, which is suitable for providing the overlap area with the glass panel  14 . 
       FIG. 6  illustrates a schematic sectional perspective view of the inner part  10  of the oven door for the microwave oven according to the prior art. 
     The inner part  10  of the oven door includes the door cover  12  and the inner glass panel  14 . The door cover  12  encloses the inner glass panel  14 . The inner glass panel  14  faces directly the oven cavity of the microwave oven in the closed state of the oven door. The door cover  12  has the L-shaped cross-section. The inner leg of said L-shaped cross-section extends parallel to the plane of the inner glass panel  14 , while the outer leg of the L-shaped cross-section encloses the inner leg, is arranged perpendicular to said inner leg and extends outwards from the inner leg. 
     The inner leg of the door cover  12  and the outer portion of the inner surface of the inner glass panel  14  overlap. In the overlap area of the inner leg of the door cover  12  and the inner glass panel  14 , said door cover  12  and inner glass panel  14  are glued together. A glue joint  18  is formed in the overlap area of the inner leg of the door cover  12  and the inner glass panel  14 . The outer portion of the inner surface of the inner glass panel  14  is connected to an outer side of the inner leg of the door cover  12  by the glue joint  18 . The inner part  10  of the oven door according to the prior art includes the glue joint  18  instead of the welded joint  16  according to the present invention. 
     Although an illustrative embodiment of the present invention has been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to that precise embodiment, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims. 
     LIST OF REFERENCE NUMERALS 
     
         
           10  inner part of the oven door 
           12  door cover 
           14  inner glass panel 
           16  welded joint 
           18  glue joint