GB2329815A

GB2329815A - Insulated mode stirrer for microwave oven

Info

Publication number: GB2329815A
Application number: GB9804254A
Authority: GB
Inventors: Sung-Ho Lee; Jung-Eui Hoh
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1997-09-29
Filing date: 1998-02-27
Publication date: 1999-03-31
Also published as: KR19990030201A; GB9804254D0; JPH11108369A; CN1213058A; KR100274253B1

Abstract

A mode stirrer 70, 90 (80, see fig 4) disposed at the bottom of a microwave oven cooking chamber comprises a metallic body plate part 73, 83 and a holder part 72, 82 of non-metallic material attached to the centre of the body plate part, which engages a drive shaft. A further non-metallic plate 87 may be bonded to the underside of the body plate part 83. The non-metallic insulating parts 72, 82, 87 serve to prevent arcing between the stirrer and the floor of the chamber. The insulating parts are preferably formed from synthetic resin.

Description

Stirrer For Use In A Microwave Oven Description The present invention relates to a stirrer for use in a microwave oven.

A microwave oven is a cooking apparatus that uses microwaves, and generally comprises, as shown in Figure 1, a cabinet 1 equipped with a magnetron, a cooking chamber 3 formed in the cabinet 1, a tray 37 on which food is placed, and a door 5 for opening/closing the cooking chamber 3. Microwaves generated by the magnetron are propagated into the cooking chamber 3, and food on the tray 37 is cooked thereby.

While the microwaves are being supplied to dthe cooking chamber 3, the tray 37 is rotated by a motor 10. Hence, the microwaves are not concentrated on a specific part of the food, and the food is uniformly cooked.

The microwave oven has a stirrer (not shown) for dispersing microwaves entering the cooking chamber 3. The stirrer is manufactured from a material which reflects the microwaves, and has several blades. The stirrer is disposed at the upper part of the cooking chamber 3, and rotates during operation of the microwave oven. The microwaves generated by the magnetron are guided by a waveguide to the cooking chamber 3, and the microwaves are dispersed by the stirrer before being propagating into the cooking chamber 3. Thus, the microwaves are dispersed and irradiate the food uniformly.

In a known microwave oven having such a stirrer, since the stirrer is disposed at the top of the cooking chamber 3, there has been a problem that, although the microwaves are uniformly distributed to the upper part of the food, they unevenly radiate onto the lower part of the food.

To overcome such a problem, a microwave oven has been proposed in which the stirrer is disposed under the tray 37 so that the microwaves uniformly irradiate the lower part of the food. Such a microwave oven is disclosed in JP-A-90-12493, and an improvement thereof (KR-A-97-49623) has been proposed by the applicant of this application.

Figures 2 and 2A show a microwave oven having a stirrer disposed under the tray 37, as disclosed in KR-A-97-49623.

As shown in Figures 2 and 2A, the tray 37 is installed at the bottom of the cooking chamber 3, and is supported by rollers 11 so that it can be rotated. The rollers 11 are mounted to a supporting ring 13.

A stirrer 50 made of metallic material is disposed under the tray 37. The stirrer 50 has several wings 51 extending in a plane therefrom, and a holder 52 is formed in the central part thereof. A depression 56 is formed at the bottom 34 of the cooking chamber 3, and the stirrer 50 is accommodated in the depression 56.

A motor assembly 60 for rotating the tray 37 and the stirrer 50 is installed under the floor 54 of the cooking chamber 3. The motor assembly 60 has first and second rotational shafts 61, 62 which are coaxially disposed one within the other, and the rotational shafts 61, 62 are contrarotated by a motor and a gear assembly.

The first rotational shaft 61 is assembled with the holder 52 of the stirrer 50, and the second rotation shaft 62 is connected to the tray 37 by a coupler 33. The stirrer 50 and the tray 37 are contrarotated by the rotational shafts 61, 62 which rotate in directions opposite to each other. Thus, the microwaves radiating into the cooking chamber 3 are dispersed by the stirrer 50, and the dispersed microwaves irradiate food placed on the tray 37. Therefore, the lower part of the food is uniformly cooked by the dispersed microwaves.

However, in these microwave ovens, there is a problem in that sparks are generated between the stirrer 50 and the bottom 34 of the cooking chamber 3 since a gap G is formed between the stirrer 50 and the bottom 34 of the cooking chamber 3.

According to the present invention, there is provided a microwave oven comprising a cooking chamber having a metallic floor and a stirrer mounted at the bottom of the cooking chamber, wherein the stirrer comprises a metallic microwave reflector and an insulating structure for preventing arcing between the reflector and floor of the cooking chamber.

Preferably, a motor is provided for driving the stirrer and the insulating structure comprises a tubular member drivingly coupling the motor to the stirrer.

Preferably, the insulating structure is integrated with a substantially planar nonconductive structure which substantially defines the form of the stirrer. More preferably, the reflector does not extend to the very edges of the non-conductive structure. Preferably, the reflector is bonded to the non-conductive structure.

Embodiments of the present invention will now be described, by way of example, with reference to Figures 3 to 6 of the accompanying drawings, in which: Figure 1 is a perspective view of a known microwave oven; Figure 2 is a partial side sectional view of the microwave oven in which a stirrer is disposed at the bottom of the cooking chamber; Figure 2A is a partial, enlarged view of Figure 2; Figure 3 is an enlarged perspective view of a first stirrer according to the present invention; Figure 4 is a side sectional view of a second stirrer according to the present invention; Figure 5 is a perspective view of the stirrer shown in Figure 4; and Figure 6 is a side sectional view of a third stirrer according to the present invention.

In the following description, the features common to the described embodiments and the above-described prior art will not be described again in detail.

Referring to Figure 3, the tray 37 is installed at the bottom of the cooking chamber, and the stirrer 70 is installed in the depression 56 formed at the bottom 34. The stirrer 70 and the tray 37 are assembled respectively to the first and second rotational shafts 61, 62 of the motor assembly 60.

The stirrer 70 is comprised of a body plate part 73 and a holder part 72. The body plate part 73 is made of a metallic material that can reflect microwaves, and the holder part 72 is made of a nonmetallic material having strong insulating and heat-resisting properties. Preferably, the holder part 72 is manufactured from a synthetic resin. The holder part 72 is attached to the central part of the body plate part 73 with a bonding agent. The bonding agent is appropriately selected in consideration of the characteristics of the holder part 72 and the body plate part 73.

The body plate part 73 has a plurality of blades 74 extended in a plane therefrom.

The blades 74 function to disperse the microwaves when the stirrer 70 rotates.

A hole 75 is formed in the central part of the body plate part 73. When the rotational shafts 61, 61 are inserted to the stirrer 70, the second rotational shaft 62 passes through the hole 75 and is connected to the tray 37, and the first rotational shaft 61 is inserted into the holder part 72. Then, the stirrer 70 and the first rotational shaft 61 are fixed to each other.

Referring to Figures 4 and 5, a second stirrer 80 comprises of a body plate part 83 made of a metallic material, and a holder part 82 integrally formed with a base plate part 87. The holder part 82 and the base plate part 87 are formed from a nonmetallic material such as a synthetic resin. The base plate part 87 extends beyond the edges of the body plate part 83. The body plate part 87 has a plurality of blades 84.

Referring to Figure 6, a third stirrer 90 has a body plate part 93 made of metallic material, and a holder part 92 integrally formed with the base plate part 98. The body plate part 93 comprises a coating on the upper surface of the base plate part 97.

The holder part 92 and the base plate part 97 are made of a nonmetallic material such as a synthetic resin. The body plate part 93 has a plurality of blades 94.

The operation of the stirrer according to the embodiments of the present invention is the same with that of a conventional microwave oven. Since the holder part of the stirrer according to the present embodiment is made of a nonmetallic material such as synthetic resin, there are no sparks between the stirrer and the bottom of the cooking chamber. Moreover, in the above-described second embodiment, the body plate part is supported by the base plate part, so drooping of the stirrer is prevented.

Furthermore, according to the above-mentioned third embodiment, there is an additional advantage that the body plate part can be easily manufactured.

Claims

Claims 1. A microwave oven comprising a cooking chamber having a metallic floor and a stirrer mounted at the bottom of the cooking chamber, wherein the stirrer comprises a metallic microwave reflector and an insulating structure for preventing arcing between the reflector and floor of the cooking chamber.
2. An oven according to claim 1, including a motor for driving the stirrer, wherein the insulating structure comprises a tubular member drivingly coupling the motor to the stirrer.
3. An oven according to claim 1 or 2, wherein the insulating structure comprises a substantially planar non-conductive structure which substantially defines the form of the stirrer.
4. An oven according to claim 3, wherein the reflector does not extend to the very edges of the non-conductive structure.
5. A oven according to claim 3 or 4, wherein the reflector is bonded to the nonconductive structure.
6. A stirrer being installed at a bottom of a cooking chamber in a microwave oven, said stirrer being rotated by a motor, said stirrer for dispersing microwaves, said stirrer comprising: a body plate part having a plurality of wings extended in a planar direction thereof, said body plate part being made of a metallic material that can reflect the microwaves; and a holder part being formed at a central area of said body plate part, said holder part being assembled with a shaft of said motor, said holder part being made of a nonmetallic material.
7. The stirrer as claimed in claim 1, wherein said body plate part and said holder part are manufactured separately and attached with a bonding agent.
8. The stirrer as claimed in claim 1, further comprising a base plate part being formed at a bottom of said body plate part, said base plate part for preventing a drooping of said body plate part.
9. The stirrer as claimed in claim 3, wherein said body plate part and said holder part are made of a synthetic resin in a body.
10. The stirrer as claimed in claim 3, wherein said body plate part is formed by coating a metallic material on an upper side of said base plate which is formed together with said holder part.
11. A stirrer for a microwave oven substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.
12. A stirrer for a microwave oven substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.
13. A stirrer for a microwave oven substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.

13. A stirrer for a microwave oven substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS: Claims 1. A microwave oven comprising a cooking chamber having a metallic floor and a stirrer mounted at the bottom of the cooking chamber, wherein the stirrer comprises a metallic microwave reflector and an insulating structure for preventing arcing between the reflector and floor of the cooking chamber.

2. An oven according to claim 1, including a motor for driving the stirrer, wherein the insulating structure comprises a tubular member drivingly coupling the motor to the stirrer.

3. An oven according to claim 1 or 2, wherein the insulating structure comprises a substantially planar non-conductive structure which substantially defines the form of the stirrer.

4. An oven according to claim 3, wherein the reflector does not extend to the very edges of the non-conductive structure.

5. A oven according to claim 3 or 4, wherein the reflector is bonded to the nonconductive structure.

6. A stirrer being installed at a bottom of a cooking chamber in a microwave oven, said stirrer being rotated by a motor, said stirrer for dispersing microwaves said stirrer comprising: a body plate part having a plurality of wings extended in a planar direction thereof, said body plate part being made of a metallic material that can reflect the microwaves; and a holder part being formed at a central area of said body plate part, said holder part being assembled with a shaft of said motor, said holder part being made of a nonmetallic material.

7. The stirrer as claimed in claim 6, wherein said body plate part and said holder part are manufactured separately and attached with a bonding agent.

8. The stirrer as claimed in claim 6, further comprising a base plate part being formed at a bottom of said body plate part, said base plate part for preventing a drooping of said body plate part.

9. The stirrer as claimed in claim 8, wherein said body plate part and said holder part are made of a synthetic resin in a body.

10. The stirrer as claimed in claim 8, wherein said body plate part is formed by coating a metallic material on an upper side of said base plate which is formed together with said holder part.

11. A stirrer for a microwave oven substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

12. A stirrer for a microwave oven substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.