GB2246949A

GB2246949A - Cooking container for use with microwave ovens

Info

Publication number: GB2246949A
Application number: GB9115899A
Authority: GB
Inventors: Shuki Aoyama
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1990-07-25
Filing date: 1991-07-23
Publication date: 1992-02-19
Anticipated expiration: 2011-07-23
Also published as: JPH0482517A; FR2665067B1; KR950005785B1; KR920002996A; FR2665067A1; GB9115899D0; GB2246949B

Abstract

A cooking container for use with microwave ovens includes an outer container (20) formed from a microwave transmissible material for reserving water heated by microwaves, an inner container (21) formed from a metal and having a number of apertures (24) through which steam induced by heating the water contained in the outer container (20) is supplied to its interior, and a lid (22) formed from a metal for closing an upper opening of the outer container (20) such that a predetermined gap (G) is formed between it and the inner container (21). <IMAGE>

Description

COOKING CONTAINER FOR USE WITH MICROWAVE OVENS This invention relates to a cooking container for use with microwave ovens which is used when food stuff is cooked by way of steaming with the microwave ovens.

Cooking containers used for a steam cooking with microwave ovens have been well known. FIG. 12 illustrates one of such conventional cooking containers. An outer container 1 is formed from a microwave transmissible material such as plastics. An inner container 2 is formed from a metal and has a number of apertures 3 in the bottom so that steam is supplied into the inner container 2 through the apertures 3. The inner container 2 is placed on a stepped portion la formed on the lower inner portion of the outer container 1 such that the inner container 2 is contained in the outer container 1. A lid 4 is formed from a metal and placed on an upper flange 2a of the inner container 2 so as to close the upper opening of the inner container 2.

The case where one Japanese steam cooking, a potsteamed hotchpotch is made with the above-described cooking container will be described. The pot-steamed hotchpotch is a Japanese cooking wherein chicken, some kinds of vegetables, mushroom and the like are cut into pieces and put into a pot. Then, an egg and a suitable amount of soup are mixed and poured into the pot. These foodstuffs contained in the pot are steamed. First, the inner container 2 is contained in the outer container 1 containing a suitable amount of water. The pot containing the abovedescribed foodstuffs is put into the inner container 2. The inner container 2 is closed by the lid 4 and then, the outer container 1 is placed on a turntable provided in a cooking chamber of a microwave oven (not shown). A magnetron of the oven is energized to be oscillated.The water in the outer container 1 is heated by microwaves generated by the magnetron to be boiled. Steam is supplied into the inner container 2 through the apertures 3 so that the foodstuffs contained in the pot is steamed.

In accordance with the above-described cooking container, a gap with some width is inevitably formed between the inner container 2 and the lid 4 when it is placed on the flange 2a of the inner container 2. Since each of the inner container 2 and the lid 4 is formed from the metal, an electric potential difference occurs between the inner container 2 and the lid 4 when the microwaves are irradiated with both of them, resulting in occurrence of sparks between them. Further, since the upper opening of the inner container 2 is closed by the lid 4, the microwaves are prevented from entering the inner container 2.

Accordingly, the foodstuffs in the pot is heated only by the steam, which entails a problem that the cooking period is prolonged.

Therefore, an object of the present invention is to provide a cooking container for use with microwave ovens wherein the sparks can be prevented from occurring between the metallic inner container and the metallic lid and the cooking period can be shortened.

The present invention provides a cooking container for use with microwave ovens comprises an outer container formed form a microwave transmissible material for reserving water heated by microwaves, an inner container formed from a metal and having a number of apertures through which steam induced by heating the water contained in the outer container is supplied to the interior thereof, and a lid formed from a metal and provided for closing an upper opening of the outer container such that a predetermined gap is formed between it and the inner container.

In accordance with the above-described construction, occurrence of sparks can be prevented between the metallic inner container and the lid since the predetermined gap is formed between them. Further, since the microwaves are allowed to enter the inner container through the gap, the foodstuffs can be heated both by the steam and the microwaves. Consequently, the cooking period can be shortened.

Preferably, the lid may be provided with a packing brought into contact with the outer container when the upper opening of the outer container is closed by the lid. Since the packing provides sealing between the lid and the outer container, leakage of the steam can be prevented.

It is also preferable that the outer container and the lid be provided with knobs respectively and the knob of the lid has an engagement portion engaged with the lower portion of the knob of the outer container when the lid is turned.

Since the lid can be coupled to the outer container, it can be prevented from being lifted by the steam pressure.

The invention will be described, merely by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a partially enlarged longitudinal section of the cooking container of a first embodiment in accordance with the present invention; FIG. 2 is a longitudinal section of the cooking container; FIG. 3 is a longitudinal section of the microwave oven with the cooking container contained in cooking chamber of the microwave oven; FIG. 4 is a longitudinal side section of the microwave oven with the cooking container contained in the cooking chamber of the microwave oven:: FIG. 5 is a view similar to FIG. 1 illustrating a second embodiment of the invention; FIG. 6 is a view similar to FIG 1 illustrating a third embodiment of the invention; FIG. 7 is a view similar to FIG. 2 illustrating the third embodiment; FIG. 8 is an exploded perspective view of the cooking container; FIG. 9 is a perspective view of the lid; FIG. 10 is a side view of a knob and a hook portion of the outer container; FIGS. 11(a) and 11(b) are bottom views of the knob and hook portion of the lid for explaining detachment of the lid; and FIG. 12 is a view similar to FIG. 2 showing a cooking container of the prior art.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 4 of the accompanying drawings. First, an overall arrangement of a microwave oven is shown in FIGS. 3 and 4. An inner casing 12 is enclosed in an outer casing 11 for defining a cooking chamber 13 in its interior. A turntable 15 is provided in the lower interior of the cooking chamber 13 so as to be driven by an electric motor 14. Microwaves generated by a magnetron 16 is supplied into the cooking chamber 13 and hot air is also supplied into the cooking chamber 13 by a heater 17 and a circulating fan 18.

The cooking container used for steam cooking or for other purposes in accordance with the present invention is shown in FIG. 2. The cooking container 19 comprises an outer container 20 formed from a microwave transmissible material such as heat resistance glass, an inner container 21 formed from a metal such as aluminum, and a lid 22 formed from a metal such as stainless steel. A flange 23 is integrally formed along the upper peripheral end of the outer container 20. Also see FIG. 1. The flange 23 has a rising edge 23a integrally formed on the outer peripheral edge thereof. The flange 23 is downwardly inclined inward from the outside so as to have an upper inclined stepped surface 23b.

The inner container 21 has a curled portion 21a formed so as to be convex outward. The curled portion 21a is hung over the inner peripheral edge of the flange 23 such that the inner container 21 is suspended in the outer container 20. In execution of the steam cooking, a suitable amount of water is poured into the outer container 20 so that the water surface does not reach the bottom of the inner container 21. The inner container 21 has a number of apertures 24 formed in the bottom thereof so that the steam due to the boiling of the water contained in the outer container 20 is supplied into the inner container 21 therethrough.

The outer peripheral edge of the lid 22 is inwardly bent so as to have a generally inverted L-shaped portion 22a. The lower end of the inverted L-shaped portion 22a is placed on the inclined step portion 23b of the outer container 20 so that the upper opening of the outer container 20 or that of the inner container 21 is closed by the lid 22. In this case the outer peripheral portion 22b of the lid 22 is fitted with the inside of the rising edge 23a of the flange 23 with some clearance and accordingly, the lid 22 is placed over the flange 23 so as to be approximately concentric with the inner container 21 when the outer peripheral portion 22b of the lid 22 is fitted with the inside of the rising edge 23a of the flange 23.

The inner diameter of the inverted L-shaped portion 22a is so set as to be larger by a predetermined value than the outer diameter of the curled portion 21a of the inner container 21. Consequently, a gap G of a predetermined width, for example 2 to 4 millimeter wide, is formed between the inner container 21 and the lid 22. The lid 22 is provided with a knob 25.

When the "pot-steamed hotchpotch" is made with the above-described cooking container 19, the inner container 21 is put into the outer container 20 containing the water. A pot A containing foodstuffs for the "pot-steamed hotchpotch" is put into the inner container 21. The cover 22 is attached to the outer container 20 and then, the outer container 20 is placed on the turntable 15 in the cooking chamber 13 of the microwave oven. The magnetron 16 is energized to be oscillated so that the water in the outer container 20 is heated by the microwaves generated by the magnetron 16. The water is boiled and the steam is supplied into the inner container 21 through the apertures 24.

Consequently, the foodstuffs contained in the pot A is steamed.

In accordance with the above-described construction, a relatively large gap G is provided between the upper open end of the inner container 21 and the lower end periphery of the lid 22. Accordingly, occurrence of spark is prevented between the inner container 21 and the lid 22 even when the potential difference occurs between them under the influence of the microwaves during the cooking. Further, since the microwaves are allowed to enter the inner container 21 through the gap G, the foodstuffs in the pot A is heated by the microwaves. Thus, the foodstuffs in the pot A is heated both by the steam supplied through the apertures 24 and by the microwaves. Consequently, the foodstuffs can be heated uniformly and steamed sufficiently and the cooking period can be shortened.

An experiment made by the inventors shows that the microwave entering the inner container 21 ranges 50 to 100 W in a microwave oven whose output is 600 W and it takes about thirty minutes to complete the steam cooking while it conventionally takes about thirty-five minutes, thus shortening the cooking period by five minutes.

Further, since the lid 22 is placed on the inclined step portion 23a of the flange 23 of the outer container 20, it can be prevented from being moved as the result of vibration thereof due to rotation of the turntable 15.

The cooking container 19 of the embodiment may be used to-make other kind of cooking. For example, when curry is made with the cooking container 19, beef or the like need not be fried with a frying pan since the outer container 20 of the cooking container 19 is made of heat resistance glass. The inner container 21 is detached from the outer container 20. The beef or the like is then put into the outer container 20, which is directly put over the fire from a gas range so that the beef or the like is fried.

Subsequently, the other foodstuffs are added into the outer container 20 and it is then placed on the turntable of the microwave oven for stewing. Since the flange 23 has the upper inclined step 23a, soup can be prevented from boiling over from the outer container 20 in the case of stewing.

FIG. 5 illustrates a second embodiment of the invention. The second embodiment differs from the previous embodiment in the construction of the outer container. The outer container 26 in the embodiment has a diameter and height slightly larger than the outer container 20 in the first embodiment. The outer container 26 has a lower inside stepped portion 26a instead of the flange 23 in the first embodiment. The bottom of the inner container 21 is placed on the stepped portion 26a and the inverted L-shaped portion 22a of the lid 22 is fitted with the upper end of the outer container 26 such that the predetermined gap G is defined by the upper open end of the inner container 21 and the lower end periphery of the lid 22.

In accordance with the second embodiment, the outer container 26 is provided with the stepped portion 26a on which the inner container 21 is placed. Accordingly, when the water is poured into the outer container 26, the stepped portion 26a can be utilized as a standard of the water level.

FIGS. 6 to 11 illustrate a third embodiment of the invention. The outer container 27 has the integrally formed flange 28 at its upper end. The flange 28 has the rising edge 28a and the inclined stepped surface 28b which are substantially the same as those in the first embodiment.

Two knobs 29 are integrally formed on the rising edge 28a so as to be opposite to each other. Hooks 30 are integrally formed in the vicinity of the knobs 29 on the flange 28, respectively, as shown in FIG. 8. Each hook 30 has an upper inclined surface 30a downwardly inclined toward the nearby knob 29, as shown in FIG. 10.

The outer peripheral lower end of the lid 31 is bent to be inwardly projected so as to form an inner flange 31a.

Furthermore, a curled portion 31b continuous with the flange 31a is formed so as to be bent arcuately outward form the inside. A packing 32 is mounted on the curled portion 31b by way of the resilient mounting. The lid 31 has a central steam escape aperture 33. The lid 31 is also provided with a valve 34 which is urged by the self-weight so as to usually close the steam escape aperture 33. Two knobs 35 are mounted on the outer periphery of the lid 31 so as to be opposite to each other. Each lid knob 35 has a generally inverted L-shaped engagement portion 36 integrally formed on the lower corner portion. Each engagement portion 36 is engaged with each knob 29 of the outer container 27 when the lid 31 is turned along the inclined stepped surface 28b of the outer container 27.

In making the pot-steamed hotchpotch, the inner container 21 is put into the outer container 27 containing a suitable amount of water. The pots A each containing the foodstuffs are put into the inner container 21. The engagement portions 36 of the lid 31 are caused to pass between the knobs 29 and the hooks 30 of the outer container 27, respectively, as shown in FIG. 11(a) so that the lid 31 is placed on the inclined stepped surface 28b of the flange 28. If the engagement portions 36 are placed on the respective upper surfaces of the hooks 30 in this case, the engagement portions 36 slide down along the inclined surfaces 30a respectively with the lid 31 slightly turned and fall down between the knobs 29 and the hooks 30 respectively since the upper surfaces of the hooks 30 are formed into the inclined surfaces 30a. Dowel marks 37 are provided on the knobs 35 of the lid 31 and the hooks 30 of the outer container 27, respectively as shown in FIGS. 8 and 9 in order that the lid 31 can be readily positioned so that the engagement portions 36 pass between the knobs 29 and the hooks 30 respectively.

When the lid 31 is placed on the flange 28 as described above, the packing 32 is resiliently deformed so as to inwardly fall down along the inclined stepped surface 28b.

As a result, the packing 32 is brought into a face-to-face contact with the inclined stepped surface 28b.

Subsequently, when the lid 31 is turned in the direction of arrow B in FIG. 11(a), the engagement portions 36 of the lid 31 are engaged with the lower portions of the knobs 29 of the outer container 27 respectively as shown in FIG. 11(b).

Consequently, the packing 32 is slightly pressed against the inclined stepped portion 28b of the flange 28.

On the other hand, when the lid 31 is detached from the outer container 27, fingers are put the knobs 35 of the lid 31 and the hooks 30 of the outer container 27 and the lid 31 is turned in the direction opposite arrow B, as shown in FIG. 11(b). The engagement portions 36 are disengaged from the knobs 29 of the outer container 27 respectively and then, the lid 31 is detached.

In accordance with the third embodiment, the curled portion 31b is formed along the outer periphery of the lid 31. Consequently, the lid 31 can be reinforced and can be prevented from being distorted. Further, since the packing 32 is provided on the lid 31 so as to be brought into contact with the flange 28 of the outer container 27, an airtight sealing can be achieved between the outer container 27 and the lid 31. Consequently, the steam pressure can be increased in the outer container 27, which can provides for further shortening of the cooking period. The packing 32 self-deforms inward along the inclined stepped surface so as to be brought into face-to-face contact with the same when the lid 31 is placed on the outer container 27.

Accordingly, the steam pressure acts on the faces in contact. Consequently, the sealing effect of the packing 32 can be further improved and the steam leakage can be prevented with reliability.

Further, since the outer container 27 and the lid 31 are provided with the knobs 29 and 35 respectively, handling of these parts can be improved. Since the knobs of the lid 31 are provided with the respective engagement portions 36, the knobs 29 are engaged with the respective engagement portions 36 so that the lid 31 is coupled to the outer container 27. Consequently, even when the steam pressure is raised in the outer container 27, the lid 31 can be prevented from floating as the steam pressure in the outer container 27 is raised and the steam leakage can be prevented. Consequently, the steam pressure in the outer container 27 can be further raised and accordingly, the cooking period can be further shortened.

A relatively large force is needed when the lid 31 is turned to be detached from the outer container 27. When the force is applied only to the lid 31, the outer container 27 is turned together with the lid 31, which makes it difficult to detach the lid 31 from the outer container 27. However, the outer container 27 is provided with the hooks 30 in the present invention. Fingers are put onto the knobs 35 of the lid 31 and the hooks 30 of the outer container 27 and then, forces are applied to the lid 31 and the outer container 27 so that the lid 31 is turned. Since the forces applied to the lid 31 and the outer container 27 act in the directions opposite to each other, the engagement portions 36 of the lid 31 can be readily disengaged from the respective knobs 29 of the outer container 27 without movement of the outer container 27.

When the outer container 1 of the conventional cooking container is used to boil or cook rice, the metallic lid 4 is too light and accordingly, the lid 4 is desirable to be replaced by another glass lid. However, the microwaves enter the outer container 1 through the glass lid and the upper part of the rice in the outer container is heated by the microwaves. Accordingly, the water in the upper part of the rice is reduced immediately before completion of the boiling and the upper part of the rice is disadvatageously dried. However, since the lid 31 is coupled to the outer container 27 in the present invention, the metallic lid 31 can also be used in cooking rice. Consequently, the microwaves are not irradiated onto the upper part of the rice and accordingly, the upper part of the rice can be prevented from being dried.

The foregoing disclosure and drawings are merely illustrative of the principles of the present invention and are not to be interpreted in a limiting sense. The only limitation is to be determined from the scope of the appended claims.

Claims

WE CLAIM:

1. A cooking container for use with microwave ovens, comprising: a) an outer container formed form a microwave transmissible material for reserving water heated by microwaves; b) an inner container formed from a metal and having a number of apertures through which steam induced by heating the water contained in the outer container is supplied to the interior thereof; and c) a lid formed from a metal and provided for closing an upper opening of the outer container such that a predetermined gap is formed between it and an upper open end of the inner container.

2. A cooking container for use with microwave ovens according to claim 1, wherein the lid is provided with a packing brought into contact with the outer container when the upper opening of the outer container is closed by the lid.

3. A cooking container for use with microwave ovens according to claim 1, wherein the lid has a curled portion formed in the peripheral edge thereof so as to be arcuately bent outward from the inside.

4. A cooking container for use with microwave ovens according to claim 3, wherein the curled portion of the lid is provided with a packing brought into contact with the outer container when the upper opening of the outer container is closed by the lid.

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5. A cooking container for use with microwave ovens according to claim 1, 2, 3 or 4, wherein the outer container has an inclined stepped surface formed on the upper edge thereof so as to be downwardly inclined toward the inside and the lid is placed on the inclined stepped surface when the upper opening of the outer container is closed by the lid.

6. A cooking container for use with microwave ovens according to claim 1, 2, 3 or 4, wherein the outer container has an stepped surface formed on the upper edge thereof and the upper end periphery of the inner container and the periphery of the lid are placed on the stepped surface.

7. A cooking container for use with microwave ovens according to claim 1, 2, 3 or 4, wherein the outer container has a stepped portion formed on the lower inner side wall thereof and the inner container is placed on the stepped portion.

8. A cooking container for use with microwave ovens according to any one of claims 1 to 7, wherein the outer container and the lid are provided with knobs respectively and the knob of the lid has an engagement portion engaged with the lower portion of the knob of the outer container when the lid is turned.

9. A cooking container for use with microwave ovens according to claim 8, wherein the outer container has at least one hook portion on which a finger is hung when the lid is turned so that the engagement portion of the lid knob is disengaged from the outer container knob.

10. A cooking container for use with microwave ovens substantially as herein described with reference to the accompanying drawings.