Combination microwave and gas oven

Abstract

A combination microwave and gas oven, in which an object to be heated is heat-treated by microwave energy and air heated by a gas burner inside a combustion chamber and forced to be circulated by a fan. A microwave introducing port to the heating cavity is covered with a heat insulating member provided with a film which can reflect the radiant energy transferred to the direction of the microwave introducing port. To prevent the leakage of microwave from the heating cavity especially related to a shaft of the fan which is connected to a driving motor located outside the heating cavity, a choke cavity for terminating leaked microwave from said cavity is provided.

What is claimed is: 
     
       1. A combination microwave and gas oven which comprises: an outer casing, a heating cavity defined by walls within said outer casing, means for supplying microwave energy into said heating cavity, a combustion chamber positioned adjacent to said heating cavity within said outer casing, a door means adapted to selectively open and close an opening defined at one side of said heating cavity, a gas burner positioned within said combustion chamber for supplying heated air to said heating cavity, a circulation fan positioned within a housing and communicating with said heating cavity for circulating said heated air inside said heating cavity, first microwave screen means, positioned within said outer casing on the side thereof opposite said door means for preventing the leakage of microwave energy from said heating cavity through said housing, an exhaust passage positioned between said heating cavity and said outer casing, for allowing said heated air to flow out of said outer casing, and seal means interposed between said door means and a periphery of said opening of said heating cavity for preventing the leakage of microwave energy and heated air from inside of said heating cavity to outside of said heating cavity through the space between said door means and the periphery of said opening.   
     
     
       2. A combination microwave and gas oven as claimed in claim 1, including a connecting through hole between said heating cavity and said combustion chamber and second microwave screen means positioned on said connecting through hole. 
     
     
       3. A combination microwave and gas oven as claimed in claim 1 and including a microwave introducing port, and a cover means for heat insulating and microwave transmitting, said cover means being positioned at said microwave introducing port to protect said means for supplying microwave energy from overheating. 
     
     
       4. A combination microwave and gas oven as claimed in claim 3, wherein said cover means comprises a medium for reflecting radiant energy transmitted from the inside of said heating cavity. 
     
     
       5. A combination microwave and gas oven as claimed in claim 4, wherein said medium is positioned to face an object to be heated. 
     
     
       6. A combination microwave and gas oven as claimed in claim 1, including exhaust duct means, exhaust tubes extending from said heating cavity and coupled to said duct means, and an air exhaust duct for cooling said means for supplying microwave energy coupled to said duct means. 
     
     
       7. A combination microwave and gas oven as claimed in claim 1, wherein seal means is securely attached to a peripheral corner of said door wherein said seal means is interposed by said door and a corner of the periphery of the opening of said heating cavity when said door is closed cavity when said door is closed. 
     
     
       8. A combination microwave and gas oven as claimed in claim 1, wherein each timer operating knob for operating said means supplying microwave energy and said gas burner independently operate said means supplying microwave energy and said gas burner. 
     
     
       9. A combination microwave and gas oven as claimed in claim 1, wherein said combustion chamber is located under said heating cavity. 
     
     
       10. A combination microwave and gas oven as claimed in claim 1, including exhaust ports at the upper portion of said heating cavity. 
     
     
       11. A combination microwave and gas oven as claimed in claim 1, including a microwave mode averaging means at a microwave introducing port located above said heating cavity. 
     
     
       12. A combination microwave and gas oven as claimed in claim 1, wherein said heating cavity is covered with heat insulating layers. 
     
     
       13. A combination microwave and gas oven as claimed in claim 1, including a flow rectifying member in front of said circulation fan for enhancing the circulated flow of heated air within said heating cavity. 
     
     
       14. A combination microwave and gas oven as claimed in claim 1, wherein said housing is provided by recessing the opposite side portion of said heating cavity, said housing having a microwave screening, porous board in front thereof. 
     
     
       15. A combination microwave and gas oven as claimed in claim 1, wherein said motor positioned outside said housing for driving said circulation fan is covered by a microwave insulating member at the rear end thereof. 
     
     
       16. A combination microwave and gas oven as claimed in claim 1, wherein said outer casing is provided with an inlet portion to draw air into a blower therein, said air introduced contacting with said heat insulating layers for cooling said heat insulating layers. 
     
     
       17. A combination microwave and gas oven as claimed in claim 16, wherein said air introduced is passed through the vicinity of said motor to cool said motor therewith on its way to said blower. 
     
     
       18. A combination microwave and gas oven as claimed in claim 1, wherein said first microwave screen means comprises a fan having a back board for cooling said motor positioned at the rear of the shaft of said circulation fan, said fan having a back board for cooling, said fan having a diameter which is more than a half length of a fundamental wavelength generated by said means for supplying microwave energy, an outer box having an open side on a side facing said fan, said outer box being securely fixed to the rear of said housing surrounding said shaft, the diameter of said box being approximately the same as said diameter of said fan, and a silk-hat shaped member fixed to an inner surface of said outer box at its top surface, said silk-hat shaped member having a smaller diameter than said diameter of said outer box, said silk-hat shaped member being interposed between said fan and said outer box, thereby forming a choke cavity for terminating leaked microwave energy from said heating cavity.