US3166663A - Microwave oven - Google Patents

Description

Jan. 19, 1965 K. FRITZ 3,166,663

MICROWAVE OVEN Filed July 15. 1960 INVEN TOR KARL FRITZ KENWAY, JENNEY, WlTTER & H|LDRETH ATTORNEYS 3,166,663 MICROWAVE OVEN Karl Fritz, Freiburg, Breisgau, Germany, assignor to Miwag Miirrnwellen'AG., Basel, Switzerland, a corporation of Switzerland Fiied July 13, 1W0, Ser. No. 42,631

11 Claims. (Ci. 219-1035) This invention relates to microwave ovens, particularly to those of the tunnel type employed for continuous operation. In general, the invention provides continuous sealing of the treating chamber against the escape of microwave energy.

Microwave ovens are commonly used for various types of treatments, such as heating, with microwave energy. In one known type the objects to be treated are advanced continuously through the oven by means of a conveyor belt, conveyor chain, or rollers, but in them microwave energy is lost unless means are provided to seal the inlet and outlet passageways. For this purpose sealing gates of various types have been employed to form a lock which effects a continuous closure of the entry and exit passageways. The operation of these gates requires an interruption of the motion of the objects to be treated it loss of energy under continuous operation of the microwave generator is to be prevented.

The present invention provides continuous sealing of the oven against the escape of microwave energy by means of a conveyor having a plurality of spaced panels which are arranged to extend across the entry passageway and exit passageway to provide a continuous closure of these passageways while being advanced through them. Within the oven, the panels serve to carry the objects to be treated and expose them to the source of microwave energy.

In a preferred embodiment of this invention, the oven forms a horizontal chamber which communicates with a source of microwave energy in a conventional manner. Entry and exit conduits extend vertically from the ends of the oven and the conveyor thus runs down through the entry conduit, horizontally through the tunnel and upwardly through the exit conduit. The panels are carried by the conveyor in a constantly horizontal position, and thus serve to block the entry conduit and the exit conduit from the escape of microwave energy during their passage through the conduits. In the horizontal chamber the panels are parallel to the length of the chamber and cause the objects carried by them to be exposed to the radiation.

The conveyor panels are preferably formed with edge walls each having an annular groove, which in conjunction with the walls of the entry and exit conduits, forms a conventional quarter-wave chamber having high impedance. An over-all effective seal is thereby maintained even when direct electrical contact between the panels and the walls of the entry and exit conduits is not made. A further preferred feature of a microwave oven of this invention is a spacing of the panels in the entry and exit conduits such that the chamber formed between them does not exhibit cavity resonance. These features will obviously depend upon the particular frequency employed, from which the proper dimensions can *be calculated by well known procedures.

This invention is described in detail below with reference to the accompanying drawing, in which a sectional elevation of the presently preferred embodiment is shown schematically.

In the embodiment illustrated, the microwave oven is embodied principally in a horizontal tunnel 1, having typically a rectangular cross section. Microwave energy is supplied to the oven from a generator 2 through a wave guide 3 and slots 4 formed in the upper wall of the oven United States Patent "ice 1. An entry conduit 5 and an exit conduit 6 extend vertically from the ends of the tunnel, and through these are carried a plurality of spaced panels 7, of metal or other electrically conductive material, which constitute a conveyor by which objects to be treated are carried into, through, and out of the oven. The panels 7 are typically carried between chains 10 (only one being shown) supported on suitable sprockets and driven by conventional means (not shown). The panels 7 are connected between the chains 10 in a manner such that the panels always hang in a horizontal position and substantially completely block the entry conduit 5 and the exit conduit 6. The chains run beside the panels, conveniently in groves provided in opposite side walls of the entry and exit conduits 5 and 6 where the space they occupy is constantly closed to the escape of microwave energy.

Most effective sealing by means of the panels 7 is provided by forming their edges 8 with an inwardly extending annular groove 9 to form quarter-wave trap. The panels thus assume a form of a metallic box, open at its bottom and having side walls provided with annular indentations one-quarter wave length deep.

From the foregoing description it will be seen that objects carried by the panel 7 are exposed within the tunnel 1 to the microwave energy supplied through the slots 4. The panels further serve while bringing the objects into the tunnel through the entry conduit 5 and while bringing the object's out of them through the exit conduit 6, to provide a seal against the escape of microwave energy by blocking these conduits. For this purpose the conduits are at least as long as the space between the panels so that at least one is always present within each conduit.

Although this invention has been described with reference to its preferred embodiment, it is contemplated that obvious modifications will occur to those skilled in the art and that such modifications may be made without departing from the scope of this invention. In particular, it is noted that microwave ovens, including the means by which they are supplied with microwave energy, and also numerous types of conveyor systems are well known to the art and any of numerous conventional types may obviously be employed in the practice of this invention.

Having thus disclosed my invention and described in detail a preferred embodiment thereof, I claim and desire to secure by Letters Patent:

1. Apparatus for treating objects with microwave energy comprising a horizontal treating chamber, a source of microwave energy communicating with said chamber, a Vertical entry conduit leading to said chamber, a vertical exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced horizontal panels for supporting objects to be treated in exposure to said source, said panels being carried horizontally to extend across said entry conduit and exit conduit during their passages therethrough and provide a seal therein preventing the escape of microwave energy from said chamber.

2. Apparatus for treating objects with microwave energy comprising a horizontally-extending treating chamber, a source of microwave energy communicating with said chamber, a vertically-extending entry conduit leading to said chamber, a vertically-extending exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced panels for supporting objects to be treated in exposure to said source, said panels being arranged to 3 extend across said entry conduit and exit conduit during their passages therethrough and each having edge walls formed with an annular groove forming with the walls of said entry conduit and exit conduit a quarter-wave trap, thereby providing a seal within said conduits preventing the escape of microwave energy from said chamber.

3. Apparatus for treating objects with microwave energy comprising a horizontally-extending treating chamber, a source of microwave energy communicating with said chamber, a vertically-extending entry conduit leading to said chamber, a vertically-extending exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced panels for supporting objects to be treated in exposure to said source, said panels being arranged to extend across said entry conduit and exit conduit during their passages therethrough and said conduits being longer than the space between said panels whereby said panels form a seal within said conduits preventing the escape of microwave energy from said chamber.

4. Apparatus for treating objects with microwave energy comprising a horizontally-extending treating chamber, a source of microwave energy communicating with said chamber, a vertically-extending entry conduit leading to said chamber, a. vertically-extending exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced panels for supporting objects to be treated in exposure to said source, said conduits being longer than the space between said panels, and said panels being arranged to extend across said conduits during their passages therethrough and each having edge walls formed with an annular groove forming with the walls of said conduits a quarter-wave trap, whereby a seal with said conduits is provided.

5. Apparatus as defined by claim 3 wherein the panels are spaced apart an amount forming an aresonant cavity between the panels within the entry and exit conduits.

6. Apparatus as defined by claim 4 wherein the panels are spaced apart an amount forming an aresonant cavity between the panels within the entry and exit conduits.

7. Apparatus for treating objects with microwave energy comprising a horizontal treating chamber, a source of microwave energy communicating with said chamber, a verticfl entry conduit leading to said chamber, a vertical exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced horizontal panels for supporting objects to be treated in exposure to said source, said panels being carried horizontally to extend across said entry conduit and exit conduit during their passages there'- through and each having edge walls formed with an annular groove forming with the walls of said entry conduit and exit conduit a quarter-wave trap, thereby providing a seal within said conduits. preventing the escape of microwave energy from said chamber.

8. Apparatus for treating objects with microwave energy comprising a horizontal treating chamber, a source of microwave energy communicating with said chamber, a vertical entry conduit leading to said chamher, a vertical exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced horizontal panels for supporting objects to be treated in exposure to said source, said panels being carried horizontally to extend across said entry conduit and exit conduit during their passages therethrough, and said conduits being longer than the space between said panels whereby said panels form a seal within said conduit-s preventing the escape of microwave energy from said chamber.

9. Apparatus for treating objects with microwave energy comprising a horizontal chamber, a source of microwave energy communicating with said chamber, a vertical entry conduit leading to said chamber, a vertical exit conduit leading from said chamber, and conveyor means for leading objects to be treated through said entry conduit, chamber, and exit conduit, said conveyor including a plurality of spaced horizontal panels for supporting objects to be treated in exposure to said source, said conduits being longer than the space betweensaid panels, and said panels being carried horizontally to extend across said conduits duringtheir passages therethrough and each having edge Walls formed with an annular groove forming with the walls of said conduits a quarter-wave trap, whereby a seal with said conduits is provided.

10. Apparatus as defined by claim 8 wherein the panels are spaced apart an amount forming an aresonant cavity between the panels within the entry and exit conduits.

11. Apparatus as defined by claim 9 wherein the panels are spaced apart an amount forming an aresonant cavity between the panels within the entry and exit conduits.

References Cited the file of this patent UNITED STATES PATENTS 2,467,230 Revercomb et al Apr. 12, 1949 2,868,939 Pound Jan. 13, 1959 FOREIGN PATENTS 1,260,933 France Apr. 196i

Claims (1)

1. APPARATUS FOR TREATING OBJECTS WITH MICROWAVE ENERGY COMPRISING A HORIZONTAL TREATING CHAMBER, A SOURCE OF MICROWAVE ENERGY COMMUNICATING WITH SAID CHAMBER, A VERTICAL ENTRY CONDUIT LEADING TO SAID CHAMBER, A VERTICAL EXIT CONDUIT LEADING FROM SAID CHAMBER, AND CONVEYOR MEANS FOR LEADING OBJECTS TO BE TREATED THROUGH SAID ENTRY CONDUIT, CHAMBER, AND EXIT CONDUIT, SAID CONVEYOR INCLUDING A PLURALITY OF SPACED HORIZONTAL PANELS FOR SUPPORTING OBJECTS TO BE TREATED IN EXPOSURE TO SAID SOURCE, SAID PANELS BEING CARRIED HORIZONTALLY TO EXTEND ACROSS SAID ENTRY CONDUIT AND EXIT CONDUIT DURING THEIR PASSAGES THERETHROUGH AND PROVIDE A SEAL THEREIN PREVENTING THE ESCAPE OF MICROWAVE ENERGY FROM SAID CHAMBER.

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