US4728762A — Microwave heating apparatus and method

Claim 1

Independent Claim 98 words

In an apparatus for use with a source of microwave energy for heating and cooking a food product: a chamber in which the food product is placed, means for introducing no more than about 25 percent of the microwave energy from the source into the chamber to heat the food product directly and preventing the remainder of the microwave energy from entering the chamber, a microwave energy absorber capable of being exposed to the microwave energy for heating air near the absorber, and means for circulating the heated air around the food product to further heat the product.

Claim 2

Dependent Claim 98 words

In an apparatus for use with a source of microwave energy for heating and cooking a food product: a chamber in which the food product is placed, means for introducing no more than about 25 percent of the microwave energy from the source into the chamber to heat the food product directly and preventing the remainder of the microwave energy from entering the chamber, a microwave energy absorber capable of being exposed to the microwave energy for heating air near the absorber, and means for circulating the heated air around the food product to further heat the product.

Claim 3

Dependent Claim 24 words

The apparatus of claim 1 including a platform through which the heated air can pass freely for supporting the food product in the chamber.

Claim 4

Dependent Claim 19 words

The apparatus of claim 2 wherein the platform is fabricated of a material which is transparent to microwave energy.

Claim 5

Dependent Claim 40 words

The apparatus of claim 1 wherein the source of microwave energy comprises a microwave oven having a heating cavity, and the apparatus constitutes a unitary structure which can be inserted into and removed form the heating cavity of the oven.

Claim 6

Dependent Claim 14 words

The apparatus of claim 1 wherein the microwave energy absorber comprises a ferrite material.

Claim 7

Dependent Claim 20 words

The apparatus of claim 5 wherein the ferrite material has a Curie point temperature in excess of its operating temperature.

Claim 8

Dependent Claim 28 words

The apparatus of claim 1 wherein the absorber has a relatively large surface area to maximize heat transfer between the absorber and the air passing over the same.

Claim 9

Dependent Claim 34 words

The apparatus of claim 1 wherein the means for introducing a portion of the microwave energy into the chamber includes means for controlling the amounts of energy reaching different parts of the food product.

Claim 10

Dependent Claim 18 words

The apparatus of claim 1 wherein the means for circulating the heated air comprises an electrically energized fan.

Claim 11

Dependent Claim 19 words

The apparatus of claim 9 including a battery connected to the fan for supplying operating power to the same.

Claim 12

Dependent Claim 159 words

In apparatus for heating and cooking a food product with microwave energy: a chamber in which the food product is placed formed by a closed outer container fabricated of a material at least partially transparent to microwave energy and an inner container having an open top and bottom and side walls spaced from the corresponding walls of the outer container, the inner container having a bottom wall and being formed at least in part of a material capable of absorbing microwave energy and being heated thereby, means for introducing a portion of the microwave energy into the chamber to heat the food product directly, and means comprising a fan positioned above the open top of the inner container for circulating air rapidly in a circular pattern past the heated portion of the inner container and about the food product to effect a high degree of heat transfer from the heated container to the outer surface of the food product.

Claim 13

Dependent Claim 159 words

In apparatus for heating and cooking a food product with microwave energy: a chamber in which the food product is placed formed by a closed outer container fabricated of a material at least partially transparent to microwave energy and an inner container having an open top and bottom and side walls spaced from the corresponding walls of the outer container, the inner container having a bottom wall and being formed at least in part of a material capable of absorbing microwave energy and being heated thereby, means for introducing a portion of the microwave energy into the chamber to heat the food product directly, and means comprising a fan positioned above the open top of the inner container for circulating air rapidly in a circular pattern past the heated portion of the inner container and about the food product to effect a high degree of heat transfer from the heated container to the outer surface of the food product.

Claim 14

Dependent Claim 21 words

The apparatus of claim 11 wherein the inner container has a layer of ferrite material on the outer side wall thereof.

Claim 15

Dependent Claim 18 words

The apparatus of claim 11 wherein the inner container is fabricated of a material which reflects microwave energy.

Claim 16

Dependent Claim 127 words

In apparatus for heating and cooking a food product with microwave energy: a chamber in which the food product is placed including an enclosure positioned within the cooking cavity of a microwave oven, said enclosure having at least one microwave transparent portion through which a portion of the microwave energy can enter the chamber to heat the food product directly, air inlet and outlet openings in the enclosure, an air duct interconnecting the inlet and outlet openings outside the enclosure and inside the oven cavity, said air duct being fabricated at least in part of a microwave absorbant material which is heated by the microwave energy and serves to heat air passing through the duct, and blower means for circulating air through the duct and the chamber.

Claim 17

Dependent Claim 127 words

In apparatus for heating and cooking a food product with microwave energy: a chamber in which the food product is placed including an enclosure positioned within the cooking cavity of a microwave oven, said enclosure having at least one microwave transparent portion through which a portion of the microwave energy can enter the chamber to heat the food product directly, air inlet and outlet openings in the enclosure, an air duct interconnecting the inlet and outlet openings outside the enclosure and inside the oven cavity, said air duct being fabricated at least in part of a microwave absorbant material which is heated by the microwave energy and serves to heat air passing through the duct, and blower means for circulating air through the duct and the chamber.

Claim 18

Dependent Claim 32 words

The apparatus of claim 14 wherein the enclosure has a wall of microwave transparent material with an inner layer of microwave reflective material extending over at least a portion of the wall.

Claim 19

Dependent Claim 30 words

The apparatus of claim 14 wherein the air duct is fabricated of a microwave reflective material with a layer of microwave absorbant material on the outer wall of the duct.

Claim 20

Dependent Claim 14 words

The apparatus of claim 14 wherein the microwave absorbant material is a ferrite material.

Claim 21

Dependent Claim 19 words

The apparatus of claim 17 wherein the ferrite material has a Curie point temperature excess of its operating temperature.

Claim 22

Dependent Claim 24 words

The apparatus of claim 14 in which the air duct has a corrugated wall to maximize the heating of air passing through the duct.

Claim 23

Dependent Claim 168 words

Apparatus for heating a food product in the cavity of a microwave oven, comprising: an outer container fabricated at least in part of a material transparent to microwave energy and having a generally cylindrical side wall, a bottom wall which rests on the floor of the oven cavity, and a removable cover; an inner container fabricated of a microwave reflective material positioned coaxially within the outer container and having an open top, a side wall spaced from the side wall of the outer container, and a bottom wall spaced from the bottom wall of the outer container; microwave absorbant material on the outer side wall of the inner container for absorbing microwave energy and heating air in the region of the side wall of the inner container, and fan means positioned above the open top of the inner container for circulating the heated air through the inner container whereby a food product placed in the inner container is heated by a combination of microwave energy and heated air.

Claim 24

Dependent Claim 168 words

Apparatus for heating a food product in the cavity of a microwave oven, comprising: an outer container fabricated at least in part of a material transparent to microwave energy and having a generally cylindrical side wall, a bottom wall which rests on the floor of the oven cavity, and a removable cover; an inner container fabricated of a microwave reflective material positioned coaxially within the outer container and having an open top, a side wall spaced from the side wall of the outer container, and a bottom wall spaced from the bottom wall of the outer container; microwave absorbant material on the outer side wall of the inner container for absorbing microwave energy and heating air in the region of the side wall of the inner container, and fan means positioned above the open top of the inner container for circulating the heated air through the inner container whereby a food product placed in the inner container is heated by a combination of microwave energy and heated air.

Claim 25

Dependent Claim 24 words

The apparatus of claim 20, including a platform through which the circulating air can pass for holding the food product in the inner container.

Claim 26

Dependent Claim 19 words

The apparatus of claim 21 wherein the platform is fabricated of a material which is transparent to microwave energy.

Claim 27

Dependent Claim 14 words

The apparatus of claim 20 wherein the microwave absorbing material comprises a ferrite material.

Claim 28

Dependent Claim 19 words

The apparatus of claim 23 wherein the ferrite material has a Curie point temperature excess of its operating temperature.

Claim 29

Dependent Claim 23 words

The apparatus of claim 20 wherein the fan means comprises an electrically operated fan mounted on the removable cover of the outer container.

Claim 30

Dependent Claim 15 words

The apparatus of claim 25 including a battery for supplying operating power for the fan.

Claim 31

Dependent Claim 30 words

The apparatus of claim 20 wherein the outer container and the inner container permit only a portion of the microwave energy within the oven cavity to reach the food product.

Claim 32

Dependent Claim 118 words

Apparatus for heating a food product in the cavity of a microwave oven, comprising: an enclosure which is partially transparent to microwave energy which rests in the oven cavity and forms a cooking chamber for the food product, air inlet and outlet openings in the enclosure, an air duct interconnecting the inlet and outlet openings outside the enclosure, said air duct being fabricated at least in part of a microwave absorbant material which is heated by the microwave energy and heats air passing through the duct, and blower means for circulating air through the duct and the cooking chamber whereby a food product in the chamber is heated by a combination of microwave energy and the heated air.

Claim 33

Dependent Claim 118 words

Apparatus for heating a food product in the cavity of a microwave oven, comprising: an enclosure which is partially transparent to microwave energy which rests in the oven cavity and forms a cooking chamber for the food product, air inlet and outlet openings in the enclosure, an air duct interconnecting the inlet and outlet openings outside the enclosure, said air duct being fabricated at least in part of a microwave absorbant material which is heated by the microwave energy and heats air passing through the duct, and blower means for circulating air through the duct and the cooking chamber whereby a food product in the chamber is heated by a combination of microwave energy and the heated air.

Claim 34

Dependent Claim 35 words

The apparatus of claim 28 wherein the enclosure comprises a generally rectangular cabinet having walls fabricated of a microwave transparent material with an inner lining of microwave reflective material extending over portions of the walls.

Claim 35

Dependent Claim 30 words

The apparatus of claim 28 wherein the air duct is fabricated of a microwave reflective material with a layer of microwave absorbant material on the outer wall of the duct.

Claim 36

Dependent Claim 14 words

The apparatus of claim 30 wherein the microwave absorbant material is a ferrite material.

Claim 37

Dependent Claim 20 words

The apparatus of claim 31 wherein the ferrite material has a Curie point temperature in excess of its operating temperature.

Claim 38

Dependent Claim 41 words

The apparatus of claim 28 wherein a plenum chamber is mounted on a wall of the enclosure adjacent to the outlet opening and in communication with the air duct, and the blower means comprises a fan mounted in the plenum chamber.

Claim 39

Dependent Claim 26 words

The apparatus of claim 28 wherein the air duct has a corrugated side wall to maximize the transfer of heat to air passing through the duct.

Claim 40

Dependent Claim 91 words

In a method of heating a food product with microwave energy, the steps of: placing a chamber in a cavity of a microwave oven, placing the food product in the chamber, introducing no more than about 25 percent of the microwave energy generated by the oven into the chamber to heat the food product directly, heating a microwave absorber with a protion of the remainder of the microwave energy, passing air near the absorber to heat the air, and blowing the air through the chamber to further heat the food product.

Claim 41

Dependent Claim 91 words

In a method of heating a food product with microwave energy, the steps of: placing a chamber in a cavity of a microwave oven, placing the food product in the chamber, introducing no more than about 25 percent of the microwave energy generated by the oven into the chamber to heat the food product directly, heating a microwave absorber with a protion of the remainder of the microwave energy, passing air near the absorber to heat the air, and blowing the air through the chamber to further heat the food product.

Claim 42

Dependent Claim 15 words

The method of claim 35 wherein the food product is held in a stationary position.

Claim 43

Dependent Claim 11 words

The apparatus of claim 1 wherein the chamber is thermally insulated.

Claim 44

Dependent Claim 153 words

In apparatus for heating and cooking a food product with microwave energy: a chamber in which the food product is placed formed by a closed outer container fabricated of a material at least partially transparent to microwave energy and a closed inner container having a top, bottom and side walls spaced from the corresponding walls of the outer container to define an annulus, the inner container being formed at least in part of a material capable of absorbing microwave energy and being heated thereby, means for introducing a portion of the microwave energy into the inner container to heat the food product directly, and means comprising a fan positioned within the inner container for circulating air past the heated portion of the inner container and about the food product to effect a high degree of heat transfer from the heated portion of the inner container to the outer surface of the food product.

Claim 45

Dependent Claim 153 words

In apparatus for heating and cooking a food product with microwave energy: a chamber in which the food product is placed formed by a closed outer container fabricated of a material at least partially transparent to microwave energy and a closed inner container having a top, bottom and side walls spaced from the corresponding walls of the outer container to define an annulus, the inner container being formed at least in part of a material capable of absorbing microwave energy and being heated thereby, means for introducing a portion of the microwave energy into the inner container to heat the food product directly, and means comprising a fan positioned within the inner container for circulating air past the heated portion of the inner container and about the food product to effect a high degree of heat transfer from the heated portion of the inner container to the outer surface of the food product.

Claim 46

Dependent Claim 21 words

The apparatus of claim 38 wherein the inner container has a layer of ferrite material on the outer side wall thereof.

Claim 47

Dependent Claim 18 words

The apparatus of claim 38 wherein the inner container is fabricated of a material which reflects microwave energy.

Claim 48

Dependent Claim 25 words

The apparatus of claim 38 wherein heat insulation is disposed in the annulus to minimize heat transfer from the inner container through the outer container.

Claim 49

Dependent Claim 28 words

The apparatus of claim 38 additionally comprising vent tubing extending through both of the tops for the escape from the apparatus of steam produced in the inner container.

Claim 50

Dependent Claim 54 words

The apparatus of claim 42 wherein the top of the inner container includes means for controlling the introduction of microwave energy into the inner container through the top thereof to regulate the ratio of the microwave energy heating the food product directly and the microwave energy being absorbed by and heating the inner container.

Claim 51

Dependent Claim 44 words

The apparatus of claim 38 wherein thermal insulation is disposed in the space intermediate the top, bottom and side walls of the inner containers and the corresponding walls of the outer container to minimize heat transfer from the inner container through the outer container.

Claim 52

Dependent Claim 69 words

The apparatus of claim 38 wherein the upper portions of the walls of the inner container and the upper portions of the corresponding walls of the outer container are a unitary structure movable as a unit together, and the lower portions of the walls of the inner container and the lower portions of the corresponding walls of the outer container are a unitary structure movable as a unit together.

Claim 53

Dependent Claim 32 words

The apparatus of claim 38 wherein said material capable of absorbing microwave energy and being heated thereby is a material characterized by an absence of any Curie point temperature below 600° F.

Claim 54

Dependent Claim 215 words

Apparatus for heating a food product in the cavity of a microwave oven, comprising: an outer container fabricated at least in part of a material transparent to microwave energy and having a generally cylindrical side wall, a bottom wall supported by the floor of the oven cavity, and a removable cover; an inner container fabricated of a microwave reflective material positioned coaxially within the outer container and having a side wall spaced from the side wall of the outer container, a bottom wall spaced from the bottom wall of the outer container, and a removable cover spaced from the removable cover of the outer container; a layer of microwave absorbant material on the outer side wall of the inner container for absorbing microwave energy and heating air in the region of the side wall of the inner container; and fan means positioned within the inner container adjacent the removable cover thereof for circulating the heated air through the inner container whereby a food product placed in the inner container is heated by a combination of microwave energy and heated air; and thermal insulation disposed in the space intermediate the side walls, bottom walls and removable covers of the inner and outer containers, respectively, to minimize heat loss from the inner container through the outer container.

Claim 55

Dependent Claim 215 words

Apparatus for heating a food product in the cavity of a microwave oven, comprising: an outer container fabricated at least in part of a material transparent to microwave energy and having a generally cylindrical side wall, a bottom wall supported by the floor of the oven cavity, and a removable cover; an inner container fabricated of a microwave reflective material positioned coaxially within the outer container and having a side wall spaced from the side wall of the outer container, a bottom wall spaced from the bottom wall of the outer container, and a removable cover spaced from the removable cover of the outer container; a layer of microwave absorbant material on the outer side wall of the inner container for absorbing microwave energy and heating air in the region of the side wall of the inner container; and fan means positioned within the inner container adjacent the removable cover thereof for circulating the heated air through the inner container whereby a food product placed in the inner container is heated by a combination of microwave energy and heated air; and thermal insulation disposed in the space intermediate the side walls, bottom walls and removable covers of the inner and outer containers, respectively, to minimize heat loss from the inner container through the outer container.

Claim 56

Dependent Claim 24 words

The apparatus of claim 47 including a platform through which the circulating air can pass for holding the food product in the inner container.

Claim 57

Dependent Claim 19 words

The apparatus of claim 47 wherein the platform is fabricated of a material which is transparent to microwave energy.

Claim 58

Dependent Claim 14 words

The apparatus of claim 47 wherein the microwave absorbing material comprises a ferrite material.

Claim 59

Dependent Claim 19 words

The apparatus of claim 50 wherein the ferrite material has a Curie point temperature in excess of 600° F.

Claim 60

Dependent Claim 23 words

The apparatus of claim 47 wherein the fan means comprises an electrically operated fan mounted on the removable cover of the inner container.

Claim 61

Dependent Claim 15 words

The apparatus of claim 52, including a battery for supplying operating power for the fan.

Claim 62

Dependent Claim 26 words

The apparatus of claim 47 wherein the inner container permits only a portion of the microwave energy within the oven cavity to reach the food product.

Claim 63

Dependent Claim 20 words

The apparatus of claim 47 wherein the removable covers have vents for the escape of steam from the inner container.

Claim 64

Dependent Claim 45 words

The apparatus of claim 47 wherein the removable cover or the inner container has means for the controlled leakage of microwave energy through the removable cover into the inner container to regulate the relative heating of the food product by microwave energy and heated air.

Claim 65

Dependent Claim 33 words

The apparatus of claim 47 wherein the covers are a unitary structure movable as a unit together, and the bottom walls and side walls are a unitary structure movable as a unit together.

Claim 66

Dependent Claim 15 words

The apparatus of claim 47 wherein the microwave absorbing material is iron powder or carbon.

Claim 67

Dependent Claim 23 words

The apparatus of claim 47 wherein the microwave absorbing material is charaterized by the absence of a Curie point temperature below 600° F.

Claim 68

Dependent Claim 16 words

The method of claim 38 wherein the food product is placed in a thermally insulated chamber.

Claim 69

Dependent Claim 26 words

The apparatus of claim 38 further including as the source of microwave energy a microwave oven defining a cavity, the chamber being disposed within the cavity.

Claim 70

Dependent Claim 25 words

The apparatus of claim 1 wherein the chamber includes means for varying the amount of microwave energy being introduced into the chamber from the source.

Claim 71

Dependent Claim 92 words

In an apparatus for use with a source of microwave energy for heating and cooking a food product: a chamber for receiving the food product, means for introducing a portion of the microwave energy from the source into the chamber to heat the food product directly and preventing the remainder of the microwave energy from entering the chamber, a microwave energy absorber capable of being exposed to the microwave energy for heating air near the absorber, and means for circulating the heated air around the food product to further heat the product.

Claim 72

Dependent Claim 92 words

In an apparatus for use with a source of microwave energy for heating and cooking a food product: a chamber for receiving the food product, means for introducing a portion of the microwave energy from the source into the chamber to heat the food product directly and preventing the remainder of the microwave energy from entering the chamber, a microwave energy absorber capable of being exposed to the microwave energy for heating air near the absorber, and means for circulating the heated air around the food product to further heat the product.

Claim 73

Dependent Claim 34 words

The apparatus of claim 63 wherein the portion of the microwave energy introduced into the chasmber to heat the food product directly is on the order of 5-25 percent of the microwave energy available.

Claim 74

Dependent Claim 132 words

The apparatus of claim 63 including a closed outer container fabricated of a material at least partially transparent to microwave energy, the chamber comprising an inner container having an open top and bottom and side walls spaced from the corresponding walls of the outer container, the inner container having a bottom wall and being formed at least in part of a material capable of absorbing microwave energy and being heated thereby; and the circulating means comprising a fan positioned above the open top of the inner container for circulating air rapidly in a circular pattern past the heated portion of the inner container and about the food product to effect a high degree of heat transfer from the heated portion of the inner container to the outer surface of the food product.

Claim 75

Dependent Claim 25 words

The apparatus of claim 63 further including as the microwave energy source a microwave oven defining a cavity, the chamber being disposed within the cavity.

Claim 76

Dependent Claim 111 words

The apparatus of claim 63 including an enclosure positioned within the cooking cavity of a microwave oven, said enclosure having at least one microwave transparent portion through which a portion of the microwave energy can enter the chamber to heat the food product directly, air inlet and outlet openings in the enclosure, an air duct interconnecting the inlet and outlet openings outside the enclosure and inside the oven cavity, said air duct being fabricated at least in part of a microwave absorbant material which is heated by the microwave energy and serves to heat air passing through the duct, and blower means for circulating air through the duct and the chamber.

Claim 77

Dependent Claim 109 words

In a method of heating a food product disposed in a chamber located in the cavity of a microwave oven having a source of microwave energy, the steps of: introducing a portion of the microwave energy into the chamber to heat the food product directly while preventing the remainder of the micorwave energy from entering the chamber, exposing a microwave absorber outside of the chamber to at least some of the remainder of the microwave energy preventing from entering the chamber to heat the microwave absorber, passing air near the microwave absorber to heat the air, and circulating the air within the chamber to further heat the food product.

Claim 78

Dependent Claim 109 words

In a method of heating a food product disposed in a chamber located in the cavity of a microwave oven having a source of microwave energy, the steps of: introducing a portion of the microwave energy into the chamber to heat the food product directly while preventing the remainder of the micorwave energy from entering the chamber, exposing a microwave absorber outside of the chamber to at least some of the remainder of the microwave energy preventing from entering the chamber to heat the microwave absorber, passing air near the microwave absorber to heat the air, and circulating the air within the chamber to further heat the food product.

Claim 79

Dependent Claim 16 words

The method of claim 68 wherein the food product is placed in a thermally insulated chamber.

Claim 80

Dependent Claim 34 words

The method of claim 68 wherein the portion of the microwave energy introduced into the chamber to heat the food product directly is on the order of 5-25 percent of the microwave energy available.

Claim 81

Dependent Claim 34 words

The apparatus of claim 38 wherein the portion of the microwave energy introduced into the chamber to heat the food product directloy is on the order of 5-25 percent of the microwave energy available.

Claim 82

Dependent Claim 23 words

The apparatus of claim 38 wherein said fan means is adapted to circulate air rapidly in a circular pattern within the inner container.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-03-01	1991-08-31	1992-03-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-03-01	1995-08-31	1996-03-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-03-01	1999-08-31	2000-03-01	$7700.00	Window Closed / Lapsed

Microwave heating apparatus and method

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