CN216147855U

CN216147855U - Microwave steaming and baking oven

Info

Publication number: CN216147855U
Application number: CN202120116973.7U
Authority: CN
Inventors: 刘钦; 吴永强; 任国栋; 刘骏; 贺聪
Original assignee: Superbox Technology Beijing Co ltd
Current assignee: Superbox Technology Beijing Co ltd
Priority date: 2021-01-15
Filing date: 2021-01-15
Publication date: 2022-04-01
Anticipated expiration: 2031-01-15

Abstract

The utility model provides a microwave steaming and baking oven, comprising: the cooking box comprises a box body, wherein a cooking cavity is formed in the hollow part inside the box body; a microwave generating part configured to generate microwaves, and to conduct the microwaves into the cooking cavity to heat food to be heated; the heating device and the hot air fan are configured to enable heat generated by the heating device to form hot air and send the hot air into the cooking cavity; a temperature sensor configured to sense a temperature of the hot wind; and the sensor microwave shielding cover comprises a cover body, the cover body comprises a plurality of holes, the holes are configured to shield microwaves from entering the sensor through the microwave shielding cover, the cover body is of a columnar structure, a non-planar structure is arranged on one side facing hot air, and the cross section area of the non-planar structure in a plane perpendicular to the hot air direction is gradually increased along the hot air direction. The embodiment of the utility model can lead the packaging and microwave shielding of the temperature sensor to be tighter and lead the measurement to be more accurate.

Description

Microwave steaming and baking oven

Technical Field

The utility model relates to the technical field of kitchen electrical equipment, in particular to a microwave steaming and baking oven.

Background

In the field of kitchen appliances, microwave ovens are generally provided with a temperature sensor or probe. In the temperature sensor or the temperature probe in the prior art, because no shielding cover is arranged or the packaging and shielding are not completely tight, especially microwaves with different frequencies can penetrate through the joint of the metal shell and the shielding wire, and the AD sampling result of the temperature sensor is greatly influenced. Therefore, the temperature value sensed by the temperature sensor or the temperature probe in the prior art is easily interfered by microwaves entering the microwave sensor or the temperature probe, and the temperature measurement accuracy is seriously influenced by irregular jumping when the microwave steaming oven works.

The statements in the background section are merely prior art as they are known to the inventors and do not, of course, represent prior art in the field.

SUMMERY OF THE UTILITY MODEL

According to the embodiment of the utility model, the shielding cover with a special structure is added outside the temperature sensor, so that the problem that the temperature value measured by the temperature sensor is interfered by microwaves in the prior art is solved.

In view of at least one of the drawbacks of the prior art, the present invention proposes a microwave steaming oven comprising:

a case, a hollow part inside of which forms a cooking cavity;

a microwave generating part configured to generate microwaves, and to conduct the microwaves into the cooking cavity to heat food to be heated;

the heating device and the hot air fan are configured to enable heat generated by the heating device to form hot air and send the hot air into the cooking cavity;

a temperature sensor configured to sense a temperature of the hot air; and

sensor microwave shield cover, sensor microwave shield cover includes the cover body, wherein include a plurality of eyelets on the cover body, the eyelet configures into can shield the microwave and passes through the microwave shield cover gets into the sensor, the cover body is the columnar structure, and has non-planar structure on the one side that faces hot-blast, wherein along hot-blast direction, the cross sectional area of non-planar structure in the perpendicular to in the plane of hot-blast direction increases gradually.

According to an aspect of the present invention, a side of the cover facing the hot wind is configured to allow water droplets attached to the cover to flow in a direction of the hot wind.

According to an aspect of the utility model, wherein the cover has a cylindrical structure, a semi-arc structure or a tapered structure.

According to one aspect of the utility model, the aperture of the aperture in the cover is arranged to be less than one quarter of a microwave wavelength.

According to an aspect of the present invention, wherein the cover is made of metal, the microwave cooking oven further comprises an air duct located above the cooking cavity, wherein the hot air is dispersed into the cooking cavity along the air duct.

According to one aspect of the utility model, the temperature sensor is arranged in the air duct on a side far away from the heating device and the hot air fan.

According to an aspect of the utility model, the sensor microwave shielding case further comprises a base connected with the cover body, and the base is installed on the side wall of the box body.

According to an aspect of the present invention, further comprising a steam generator configured to blow steam generated and released by the steam generator into the cooking cavity.

According to an aspect of the present invention, further comprising a circulation fan configured to increase air flow in the cooking chamber to uniformly distribute the hot wind and/or the steam in the cooking chamber.

According to one aspect of the utility model, the end of the air duct remote from the heating device is tapered.

According to one aspect of the utility model, wherein the heating device is a carbon heating pipe, the circulation fan is a turbo fan, and the steam generator is a steam boiler.

According to an aspect of the present invention, the microwave oven further comprises a controller respectively coupled to the microwave generating part, the heating device, the steam generator and the temperature sensor, configured to control the microwave generating part to generate microwaves and monitor humidity in the cooking cavity, and control the steam generator to generate steam and control heating temperature of the heating device according to the temperature of the hot wind sensed by the temperature sensor and the humidity.

According to one aspect of the utility model, the cooking device further comprises a hot air hole plate, the hot air hole plate is arranged at the junction of the air duct and the cooking cavity, a plurality of small holes are formed in the hot air hole plate, and the hot air is dispersed into the cooking cavity through the hot air hole plate.

According to one aspect of the present invention, further comprising a steam hole plate provided below or at the bottom of the sidewall of the cooking chamber and having a plurality of small holes formed therein, the steam is dispersed into the cooking chamber through the steam hole plate.

According to an aspect of the present invention, a plurality of steam ports are provided under a rear portion or on a sidewall of the cooking cavity, and the steam is dispersed into the cooking cavity through the plurality of steam ports.

According to an aspect of the present invention, further comprising a partition wall disposed between the circulation fan and the cooking chamber, the partition wall having a plurality of circulation holes disposed thereon, wherein the circulation fan is configured such that gas in the cooking chamber exits the cooking chamber through a part of the circulation holes and re-enters the cooking chamber through another part of the circulation holes.

According to the embodiment of the utility model, the shielding cover is additionally arranged outside the temperature sensor or the temperature probe, and the shielding cover is provided with the non-planar structure with the gradually increased cross-sectional area in the plane perpendicular to the hot air direction towards the hot air direction, so that the problem of inaccurate measurement result caused by entry of microwaves due to imprecise packaging and shielding of the temperature sensor or the temperature probe in the prior art is solved, and the measurement accuracy of the temperature sensor is improved. The temperature sensor shielding cover has the outstanding characteristics of simple structure and easiness in manufacturing and mounting.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model and not to limit the utility model. In the drawings:

FIG. 1 shows a schematic diagram of a sensor microwave shield according to one embodiment of the present invention;

FIGS. 2A, 2B, and 2C respectively show schematic in-plane cross-sections of non-planar structures of a sensor microwave shield against a hot air direction, according to one embodiment of the present invention;

FIG. 3 illustrates a side view of the internal structure of a microwave cooking oven in accordance with one embodiment of the present invention; and

FIG. 4 illustrates a side view of the internal structure of a microwave cooking oven in accordance with another embodiment of the present invention.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the utility model. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

FIG. 1 shows a schematic diagram of a sensor microwave shield according to one embodiment of the present invention. As shown in fig. 1, the sensor microwave shielding case 10 includes a case 11, wherein the case 11 includes a plurality of holes 12, and the holes 12 are configured to shield microwaves from entering the sensor through the microwave shielding case 10, but allow hot air to pass through. The cover 11 is a columnar structure, and has a non-planar structure 13 on a side facing the hot air, wherein a cross-sectional area of the non-planar structure 13 in a plane perpendicular to the hot air direction is gradually increased along the hot air direction (refer to fig. 2A, 2B, and 2C below). The sensor microwave shielding case 10 further comprises a base 14 connected with the cover body 11, wherein the base 14 is installed on the inner wall of the microwave steaming oven and used for covering the sensor microwave shielding case 10 outside the sensor, such as a temperature sensor, so as to shield the microwave transmitted from the microwave steaming oven to the temperature sensor.

Fig. 2A, 2B, and 2C respectively show schematic views of cross-sections in a plane of a non-planar structure of a sensor microwave shield facing a direction of hot air according to an embodiment of the present invention. According to an embodiment of the present invention, the cover 11 has a cylindrical structure, a semi-circular arc structure or a tapered structure, and as shown in fig. 2A, 2B and 2C, the cover 11 has a semi-circular shape, a semi-circular arc shape and a triangular shape, respectively, in a cross section parallel to the direction of the heated wind, corresponding from left to right. Referring to fig. 1 and fig. 2A, 2B, and 2C, along the hot air direction (i.e. the direction from right to left in the drawing), the radian or angle of the non-planar structure 13 from right to left increases in the semicircular, semicircular arc or triangular cross section parallel to the hot air direction, so that the cross-sectional area of the non-planar structure 13 in the plane perpendicular to the hot air direction increases gradually. When the hot air is blown to the cover body 11 from right to left in the drawing, the water drops attached to the cover body 11 flow from right to left along the radian or angle of the semicircular, semicircular arc or triangular section along the direction of the hot air instead of being directly blown into the cover body 11, thereby affecting the measurement accuracy of the temperature sensor 10.

According to an embodiment of the present invention, the structure of the cover 11 is not limited to the above-mentioned three specific non-planar structures 13 on the side facing the hot wind, and those skilled in the art can understand that any structure of the cover 11 that can make the water drops attached to the cover 11 flow along the direction of the hot wind instead of directly blowing into the cover 11 and can use the hot wind to break the water film tension on the windward side of the shielding cover falls into the protection scope of the present invention.

According to an embodiment of the present invention, in order to make the cover 11 not only shield the microwave emitted from the microwave oven, but also allow the hot air to pass through and ensure that the real-time temperature acquisition of the temperature sensor 10 is not affected, the aperture of the hole 12 on the cover 11 is set to be less than a quarter of the wavelength of the microwave. According to one embodiment of the utility model, the material of the cover 11 is metal.

FIG. 3 illustrates a side view of the internal structure of a microwave cooking oven in accordance with one embodiment of the present invention. As shown in fig. 3, the microwave steaming and baking oven 100 includes: a case 110, a microwave generating part 120, a heating device 130, a hot air fan 140, a temperature sensor 150, and a sensor microwave shield case 10. The cooking chamber 101 is formed in a hollow portion of the inside of the cabinet 110, and food is placed in the cooking chamber 101 to be heated and processed. The microwave generating part 120 is optionally disposed on the top of the cooking cavity 101, and is configured to generate microwaves and conduct the microwaves into the cooking cavity 101 to heat food to be heated. The heating device 130 and the hot air fan 140 are optionally disposed at the rear of the cooking chamber 101, and are configured to generate hot air from the heat generated by the heating device 130 and send the hot air into the cooking chamber 101. The temperature sensor 150 is configured to sense the temperature of the hot air. The sensor microwave shielding case 10 is disposed outside the temperature sensor 150 and configured to shield microwaves generated by the microwave steaming oven 100 to interfere with the temperature sensor 150, so as to ensure measurement accuracy and stability of the temperature sensor 150. Referring to fig. 1 and fig. 2A, 2B and 2C, the sensor microwave shielding case 10 includes a case 11, wherein the case 11 includes a plurality of holes 12, and the holes 12 are configured to shield microwaves from entering the sensor 10 through the microwave shielding case 10, but allow hot air to pass through. The cover body 11 is a columnar structure, and a non-planar structure 13 is arranged on one side facing hot air, wherein the cross-sectional area of the non-planar structure 13 in a plane perpendicular to the hot air direction is gradually increased along the hot air direction. With regard to the specific structure of the microwave shielding case 10, reference is made to fig. 1 and the above description, which are not repeated herein.

According to an embodiment of the present invention, as shown in fig. 3, the microwave steaming oven 100 further includes an air duct 160 located above the cooking cavity 101, wherein an end of the air duct 160 away from the heating device 130 is tapered. Alternatively, the air duct 160 may be narrowed from an end near the heating device 130, or from any middle portion of the air duct 160 in a direction away from the heating device 130, so that the hot air is dispersed into the cooking cavity 101 along the air duct 160. The hot air fan 140 is disposed at the rear of the heating device 130, and when the heating device 130 generates heat, the hot air fan 140 transfers the heat forward and downward from the rear of the microwave steaming oven 100 along the wind tunnel 160 to fill the whole wind tunnel 160 and the cooking chamber 101.

FIG. 4 illustrates a side view of the internal structure of a microwave cooking oven in accordance with another embodiment of the present invention. As shown in fig. 3 and 4, according to a preferred embodiment of the present invention, the vertical section of the wind tunnel 160 is trapezoidal or triangular. When the heat is transferred forward from the rear of the microwave oven 100 along the air duct 160, the heat is forced to change the originally horizontal flow direction by hitting the "slope" 161 formed by one inclined side with a trapezoidal or triangular cross section, and then flows to the lower part of the microwave oven 100, i.e. the cooking cavity 101, and gradually fills the whole cooking cavity 101.

According to an embodiment of the present invention, as shown in fig. 3, the temperature sensor 150 is disposed inside the wind tunnel 160 on a side away from the heating device 130 and the hot wind fan 140 to sense the temperature of the hot wind blown out from the heating device 130 and the hot wind fan 140.

According to an embodiment of the present invention, as shown in fig. 1 and 3, the base 14 of the sensor microwave shielding case 10 is mounted on the side wall of the box 110 inside the air duct 160 to tightly cover the temperature sensor 150. Wherein the non-planar structure 13 of the sensor microwave shielding case 10 is arranged to face the direction from which the hot wind blows, so that the non-planar structure 13 faces the hot wind, and the water drops flow along the direction of the hot wind without being hung on the non-planar structure 13.

According to an embodiment of the present invention, as shown in fig. 3, the microwave steaming oven 100 further includes a steam generator 170, and the steam generator 170 is configured to blow steam generated and released by the steam generator 170 into the cooking cavity 101.

According to an embodiment of the present invention, as shown in fig. 3, the microwave steaming oven 100 further includes a circulation fan 180, and the circulation fan 180 is configured to increase the air flow in the cooking cavity 101 and circulate the hot wind and/or the steam in the cooking cavity 101 for uniform distribution.

According to one embodiment of the present invention, as shown in fig. 3, the heating device 130 is a carbon heating pipe, the circulation fan 180 is a turbine fan, and the steam generator 170 is a steam boiler. Specifically, the turbofan is configured such that when the turbofan rotates, a central region thereof sucks air from the inside of the cooking cavity 101, air in a middle region of the cooking cavity 101 is sucked into the turbofan and then blown out from a peripheral region of the turbofan, and such repetition and alternation are performed to realize circulation ventilation in the inside of the cooking cavity 101, thereby finally enabling the steam to uniformly fill the entire cooking cavity 101.

According to an embodiment of the present invention, the microwave steaming oven 100 further comprises a controller (not shown in the figure), which is respectively coupled to the microwave generating part 120, the heating device 130, the steam generator 170 and the temperature sensor 150, and is configured to control the microwave generating part 120 to generate microwaves, monitor the humidity in the cooking cavity 101, control the steam generator 170 to generate steam according to the temperature of the hot wind sensed by the temperature sensor 150 and the humidity, and control the heating temperature of the heating device 130.

According to an embodiment of the present invention, as shown in fig. 3 and 4, the microwave steaming and baking oven 100 further includes a hot air hole plate 162, the hot air hole plate 162 is disposed at a boundary between the air duct 160 and the cooking cavity 101, and a plurality of small holes are formed in the hot air hole plate 162, and the hot air is dispersed into the cooking cavity 101 through the hot air hole plate 162, so that the cooking cavity 101 is uniformly filled with the hot air.

According to an embodiment of the present invention, as shown in fig. 3 and 4, the microwave steaming and baking oven 100 further includes a steam hole plate 171, the steam hole plate 171 is disposed at the bottom of the cooking cavity 101 and has a plurality of small holes, and the steam is dispersed into the cooking cavity 101 through the steam hole plate 171. Through the steam hole plate 171, the steam generated by the steam generator 170 can more uniformly fill the cooking cavity 101, and the bottom of the food can be better moistened, thereby preserving the fresh taste of the food.

According to an embodiment of the present invention, as shown in fig. 3 and 4, a plurality of steam ports 172 are provided under the rear or on the sidewall of the cooking chamber 101, and the steam is dispersed into the cooking chamber 101 through the plurality of steam ports 172. The plurality of steam ports 172 function similarly to the steam hole plate 171, and thus, a detailed description thereof is omitted.

According to an embodiment of the present invention, as shown in fig. 3 and 4, the microwave steaming oven 100 further includes a partition wall 181 disposed between the circulation fan 180 and the cooking cavity 101, the partition wall 181 being provided with a plurality of circulation holes 182, wherein the circulation fan 180 is configured such that gas in the cooking cavity 101 exits the cooking cavity 101 through a part of the circulation holes and re-enters the cooking cavity 101 through another part of the circulation holes. Wherein the gas inside the cooking cavity 101 is sucked into the circulating fan 180 through a part of the circulating holes distributed in the central area of the circulating fan 180, and is released into the cooking cavity 101 through another part of the circulating holes distributed in the peripheral area of the circulating fan 180, thereby realizing a plurality of times of alternate thermal cycles inside the cooking cavity 101, so that the gas is well mixed and uniformly distributed in the cooking cavity 101. In the embodiment of fig. 3, the steam generator 170 is located behind the circulation fan 180, but the present invention is not limited thereto, and the steam generator 170 may be located below the circulation fan 180, and steam is supplied into the cooking chamber through the steam hole plate 181 or the steam port 182 through a separate pipe.

In addition, in the embodiment of the present invention, the heating device 130 and the hot wind fan 140 are used to generate hot wind, and the steam generator 170 is used to generate steam and supply the steam to the cooking cavity, which are separate devices that can be separately controlled, i.e., can be separately turned on or off, and thus can be flexibly applied to heating various types of food.

According to the embodiment of the utility model, the microwave shielding cover with a special structure is arranged outside the temperature sensor or the temperature probe, wherein the shielding cover has a non-planar structure with a gradually-increased cross-sectional area in a plane perpendicular to the hot air direction facing the hot air direction, so that the problem of inaccurate measurement result caused by entry of microwaves due to imprecise packaging and shielding of the temperature sensor or the temperature probe in the prior art is solved, and the measurement accuracy, stability and real-time performance of the temperature sensor are improved. The temperature sensor shielding cover has the outstanding characteristics of simple structure and easiness in manufacturing and mounting.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the utility model. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A microwave steaming and baking oven, comprising:

a case, a hollow part inside of which forms a cooking cavity;

a temperature sensor configured to sense a temperature of the hot air; and

the sensor microwave shielding cover comprises a cover body, wherein the cover body is provided with a plurality of holes, the holes are configured to shield microwaves and enter the sensor through the microwave shielding cover, the cover body is of a columnar structure, a non-planar structure is arranged on one side facing hot air, and the cross section area of the non-planar structure in a plane perpendicular to the hot air direction is gradually increased along the hot air direction.

2. A microwave cooking oven according to claim 1, wherein the side of the hood facing the hot blast is arranged to cause water droplets adhering to the hood to flow in the direction of the hot blast.

3. A microwave cooking oven according to claim 1 or 2, wherein the housing has a cylindrical configuration, a semi-circular arcuate configuration or a conical configuration.

4. A microwave cooking oven according to claim 1 or claim 2, wherein the aperture of the aperture in the housing is arranged to be less than a quarter of a microwave wavelength.

5. A microwave cooking oven as claimed in claim 1 or 2, wherein the material of the hood is metal, the microwave cooking oven further comprising an air duct above the cooking cavity, wherein the heated air is dispersed into the cooking cavity along the air duct.

6. A microwave cooking oven according to claim 5, wherein the temperature sensor is located within the air duct on a side remote from the heating means and hot air fan.

7. The microwave cooking oven according to claim 6, wherein the sensor microwave shield further comprises a base attached to the housing, the base being mounted to a side wall of the housing.

8. A microwave steaming oven as claimed in claim 1 or claim 2, further comprising a steam generator configured to blow steam generated and released by the steam generator into the cooking chamber.

9. The microwave cooking oven of claim 8, further comprising a circulation fan configured to increase air flow in the cooking chamber to evenly distribute the heated air and/or the steam in the cooking chamber.

10. A microwave cooking oven according to claim 5, wherein the end of the air duct remote from the heating means is tapered.

11. A microwave steaming oven as defined in claim 9, wherein the heating means is a carbon heating pipe, the circulation fan is a turbofan, and the steam generator is a steam boiler.

12. A microwave steaming oven as claimed in claim 11, further comprising a controller respectively coupled to the microwave generating part, the heating means, the steam generator and the temperature sensor, configured to control the microwave generating part to generate microwaves, and to monitor the humidity in the cooking chamber, and to control the steam generator to generate steam and to control the heating temperature of the heating means according to the temperature of the hot air sensed by the temperature sensor and the humidity.

13. The microwave steaming oven according to claim 5, further comprising a hot air hole plate provided at a boundary between the air duct and the cooking cavity, and having a plurality of small holes provided thereon, wherein the hot air is dispersed into the cooking cavity through the hot air hole plate.

14. A microwave cooking oven according to claim 1 or 2, further comprising a steam vent provided below or at the bottom of the side wall of the cooking chamber and having a plurality of apertures provided therein, the steam being dispersed into the cooking chamber through the steam vent.

15. A microwave cooking oven according to claim 1 or 2, wherein a plurality of steam vents are provided in the lower rear or side walls of the cooking chamber through which the steam is dispersed into the cooking chamber.

16. The microwave cooking oven according to claim 9, further comprising a partition wall disposed between the circulation fan and the cooking chamber, the partition wall having a plurality of circulation holes disposed therein, wherein the circulation fan is configured such that gas in the cooking chamber exits the cooking chamber through a portion of the circulation holes and re-enters the cooking chamber through another portion of the circulation holes.