JP2009024915A - Microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave oven capable of correctly detecting a state of a cooked food when two microwave radiating means are disposed. <P>SOLUTION: An infrared ray sensor 30 is disposed on a symmetric center of a pair of antenna portions 15. That is, the pair of antenna portions 15 are disposed at symmetric positions to a view of the infrared ray sensor 30. The infrared ray sensor 30 thus has an equal view range to the pair of antenna portions 15. Thus the state of the cooked food can be correctly detected when the cooked food is heated by microwave, by the pair of antenna portions 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a microwave oven.

2. Description of the Related Art Conventionally, there is known a microwave oven that accommodates food to be cooked in a heating chamber and induction-heats (microwave heating) the food to be cooked with microwaves. In the microwave oven, the microwave generated by the magnetron is guided to the antenna by the waveguide, and is radiated from the antenna to the food to be cooked in the heating chamber.
For example, in the microwave oven described in Patent Document 1, a flat antenna is disposed below the heating chamber, and two rotating stirrers are provided on the flat antenna. In this microwave oven, the microwave generated by the magnetron is radiated into the heating chamber through the flat antenna and the two rotating stirrers in order. That is, it can be said that the two rotating stirrers are the antennas closest to the heating chamber.

Moreover, in the microwave oven of patent document 2, an infrared sensor is provided in the upper part of the right side surface of a heating chamber, and the temperature of the food to be cooked in a heating chamber is detected non-contactingly by this infrared sensor. Thereby, the progress status (heating state) of cooking of the food to be cooked can be detected.
JP-A-2005-203230 JP 2002-260840 A

  In the microwave oven described in Patent Document 1, two rotating stirrers are provided. That is, this microwave oven has two wave sources (power feeding units) for microwave-heating food to be cooked. In this case, when the temperature of the food to be cooked in the heating chamber is detected by the infrared sensor of Patent Document 2, the infrared sensor may detect the temperature of the food to be cooked in a biased manner according to each wave source. . In that case, it is difficult to accurately detect the heating state of the food to be cooked, and it is also difficult to accurately detect the progress of cooking.

This invention was made in order to solve this subject, and when it is provided with two microwave radiation | emission means, the main objective is to provide the microwave oven which can detect the cooking condition of to-be-cooked food correctly. And
Another object of the present invention is to provide a microwave oven that can perform microwave heating satisfactorily.

  According to the first aspect of the present invention, the front surface is opened and closed by a door, the heating chamber for storing the food to be cooked, and the central portion in the left-right direction of the heating chamber are provided symmetrically to the heating chamber. A pair of microwave radiating means for radiating waves and a cooking food provided at the center of symmetry of the pair of microwave radiating means at a position facing the food to be cooked contained in the heating chamber from above A microwave oven characterized by including a situation detecting means.

A second aspect of the present invention is the microwave oven according to the first aspect, wherein the pair of microwave radiating means are provided on the left and right along the bottom surface of the heating chamber.
According to a third aspect of the present invention, in the microwave oven according to the first or second aspect, the pair of microwave radiating means includes a rotary microwave radiating antenna that rotates about a rotation axis. is there.

Invention of Claim 4 is provided so that the said cooking condition detection means may face a bottom face from the back upper surface of the horizontal direction center part of the said heating chamber, The one of Claims 1-3 characterized by the above-mentioned. It is a microwave oven as described in.
A fifth aspect of the present invention is the microwave oven according to the fourth aspect, wherein the cooking state detecting means has a visual field for detecting substantially the entire bottom surface of the heating chamber.

According to a sixth aspect of the present invention, the cooking status detecting means has a plurality of fields of view for detecting a central portion in the left-right direction of the bottom surface of the heating chamber from the front end to the rear end, and the plurality of fields of view are horizontally aligned on the bottom surface. The microwave oven according to claim 5, further comprising a swinging mechanism that swings the cooking condition detection unit so as to move to the cooking position.
The invention according to claim 7 includes a magnetron provided in the vicinity of the heating chamber, and a branching waveguide for guiding the microwave radiated from the magnetron to two shunts. Each of the shunts is provided with the microwave radiating means, and a branching position of the branching waveguide is formed with a hemispherical protrusion that bulges into the branching waveguide. The microwave oven according to any one of claims 1 to 6.

According to the first aspect of the present invention, a pair of microwave radiating means are provided on the left and right sides symmetrically with respect to the central portion in the left-right direction of the heating chamber. A microwave is radiated into the heating chamber by the pair of left and right microwave radiation means, and the food to be cooked accommodated in the heating chamber is cooked by microwave heating.
The cooking status detection means can be constituted by an infrared sensor, for example, and detects a change in the surface of the food to be cooked by microwave heating. Thereby, the progress of cooking can be detected.

  In the first aspect of the present invention, the cooking condition detection means is provided at the symmetrical center of the pair of microwave radiation means. In other words, the pair of microwave radiating means are arranged at positions symmetrical to the visual field of the cooking condition detecting means. For this reason, a cooking condition detection means has an equal visual field range with respect to a pair of microwave radiation means. Therefore, the cooking status can be accurately detected so that a stable finish is achieved when the cooking status of microwave heating by the pair of microwave radiation means is automatically controlled.

The pair of microwave radiating means can be installed so as to radiate microwaves from the left and right side surfaces of the heating chamber, for example. Microwave heating can be performed.
As the pair of microwave radiating means is a rotary microwave radiating antenna as described in claim 3, it is possible to radiate microwaves almost uniformly into the heating chamber.

According to invention of Claim 4, the cooking condition detection means can grasp | ascertain well the cooking condition of the foodstuff accommodated in the heating chamber from upper direction. In addition, the upper part of the back of the heating chamber is a position where it is difficult for the food to be heated to reach when the food to be heated is blown up, and the cooking state detection means is not easily contaminated by food or the like.
According to the fifth aspect of the present invention, the cooking status detection means uses the entire bottom surface of the heating chamber as the detection visual field, and can accurately detect the cooking status of the stored food.

According to the invention described in claim 6, the cooking status detection means detects the cooking status by moving the visual field from the symmetrical center of the pair of microwave radiating means to the left and right. The cooking status can be detected fairly, correctly and stably.
According to the seventh aspect of the present invention, when the microwave generated by the magnetron is guided to the pair of microwave radiating means through the branch waveguide, the microwave is reflected so as to return to the magnetron in the branch waveguide. This is prevented by the hemispherical projection, and the microwave in the branching waveguide can be guided well to each microwave radiation means.

  In other words, by providing a hemispherical projection at the branching position of the branching waveguide, the impedance matching of the microwave at the branching position is improved, and the microwave output from the magnetron is suppressed from being reflected to the magnetron side. Can do.

In the following, a microwave oven (microwave oven steam range) will be described as an example, but the present invention is naturally applicable to a microwave oven function only.
<Basic configuration of microwave oven>
FIG. 1 is a front right perspective view of a microwave oven 1 as a food cooking device according to an embodiment of the present invention. FIG. 2 shows a state in which the door 2 is opened in FIG. FIG. 3 is a bottom view of the microwave oven 1. FIG. 4 is a front upper perspective view of the casing 4 in a state in which the door 2 and the decorative plate 3 (outer cover plate) are removed. FIG. 5 is a plan view of the recess 16 that is the bottom of the heating chamber 11 and shows the arrangement and shape of the rotating antennas 20A and 20B. FIG. 6A is an image view of microwave radiation in the diffusion mode, and FIG. 6B is an image view of microwave radiation in the concentrated mode. FIG. 7 is a schematic diagram for explaining how the visual field 32 moves in the heating chamber 11 in accordance with the swinging of the infrared sensor 30 serving as a cooking status detection unit. FIG. The case where an example is applied is shown, and FIG. 7B shows the case where a comparative example is applied. FIG. 8 is a front view of the casing 4 with the door 2 removed. FIG. 9 is a view showing a part of the rear heater 23 extracted. FIG. 10 is a photograph of a prototype showing the inside of the heating circulation chamber 74. FIG. 11 is a right sectional view of the casing 4 in a state in which the door 2 and the decorative plate 3 (outer cover plate) are removed. FIG. 12A is a block diagram showing an electrical configuration related to the preheating process of the microwave oven 1, and FIG. 12B is a flowchart for explaining the preheating process. FIG. 13 is a front left perspective view of the casing 4 with the door 2 and the decorative plate 3 (outer cover plate) removed. FIG. 14 is a front right perspective view of the casing 4 with the door 2 and the decorative plate 3 (outer cover plate) removed. FIG. 15 is a front right perspective view of the superheated steam generation unit 51. FIG. 16 is an exploded perspective view of the superheated steam generation unit 51 shown in FIG. FIG. 17 is an exploded perspective view of the superheated steam generation unit 51 as viewed from the front left side. FIG. 18 is a view in which a square plate 25 and a wire mesh 7 are added to FIG. FIG. 19 is a right side view of the superheated steam generation unit 51 according to a modification.

Hereinafter, for convenience of explanation, the direction in which the door 2 is provided in FIG. 1 is defined as the front (front side), and the direction of the microwave oven 1 is specified with reference to the time when the microwave oven 1 is viewed from the front side (the illustrated direction arrow). reference). The left-right direction is synonymous with the width direction.
The microwave oven 1 has a casing 4 that forms an outer shell thereof. As shown in FIG. 2, the casing 4 has a metal frame 12 in the shape of a hollow box whose front surface is open (this portion is referred to as an opening 8), and the outside (left and right outer surfaces and upper and outer surfaces) of the frame 12. ) And a decorative board 3 (outer cover board). A heating chamber 11 is formed by the frame 12. The heating chamber 11 is a horizontally long, substantially rectangular parallelepiped space defined by the left and right side walls, the top wall, the bottom wall, and the rear wall of the frame 12, and has an opening 8 on the front surface. The bottom wall forms a recess 16 that is recessed over substantially the entire area (see FIG. 4). The flat bottom plate 6 is placed so as to close the recess 16 from above. That is, the bottom surface of the heating chamber 11 has a double structure of the bottom plate 6 on which the food to be cooked is placed and the concave portion 16 recessed below.

  A plurality of rails 24 extending in the front-rear direction are provided on each inner surface of the left and right side walls (three in this embodiment) at regular intervals in the vertical direction. Hereinafter, for convenience of explanation, these rails 24 may be distinguished from the rails 24U, 24M, and 24L in order from the top. The rail 24 protrudes into the heating chamber 11. As shown in FIG. 18, the tray-shaped square dish 25 can be held in a state of floating from the bottom plate 6 by the left rail 24 and the right rail 24 facing the rail 24. A food to be cooked can also be placed on the square dish 25.

  A wire mesh 7 can be placed on the square plate 25. The metal mesh 7 includes a flat portion 26 extending in the horizontal direction and leg portions 27 extending downward from both ends in the width direction of the flat portion 26. When the wire mesh 7 is placed on the square plate 25, the wire mesh 7 is held such that the legs 27 fit into the square plate 25 and the flat portion 26 floats from the bottom surface of the square plate 25. A cooked food can also be placed on the wire mesh 7. In that case, the food to be cooked is placed on the flat portion 26, and the salt content, fats and oils and the like exuded from the heated food to be cooked are received by the square dish 25 below the flat portion 26.

  As shown in FIG. 2, a door 2 that opens and closes the opening 8 is provided on the front surface of the casing 4. The door 2 rises around the rotation shaft extending in the width direction at the lower end thereof (see FIG. 1), and the door 2 tilts forward from the closed position to open the opening 8 to open the door 2. Is rotated between an open position (see FIG. 2) where the inner surface of the plate is substantially flush with the bottom plate 6. As shown in FIG. 1, a handle 9 is provided at the upper end and an operation panel 10 is provided at the lower end on the front of the door 2. By grasping the handle 9, the door 2 can be rotated between the open position and the closed position described above. By operating the operation panel 10, it is possible to set cooking conditions and give instructions for starting cooking to a control unit (not shown) built in the casing 4. In addition, the cooking status is displayed on the operation panel 10.

  As shown in FIG. 3, a magnetron 13 that generates a microwave and a waveguide 14 (branch waveguide) that guides the microwave are provided on the bottom surface of the casing 4. The magnetron 13 is disposed in the vicinity of the heating chamber 11 in the center in the width direction of the rear end portion of the bottom surface of the casing 4 (frame 12) (see also FIG. 11). The waveguide 14 accommodates the antenna 29 of the magnetron 13 and has a T-shape in a bottom view that extends from the magnetron 13 to the front and then branches to the left and right. Note that the left and right branch portions of the waveguide 14 are each referred to as a shunt 18. The microwave radiated from the magnetron 13 is guided to each shunt 18 by the waveguide 14. A hemispherical protrusion 28 bulging into the waveguide 14 is formed at the branch position on the inner wall surface of the waveguide 14 (see also FIG. 11). The microwave that has reached the branching position of the waveguide 14 from the antenna 29 of the magnetron 13 hits the protrusion 28 and is hardly reflected to the magnetron 13 side, and smoothly flows to each shunt 18 as shown by the arrows in the figure. To be distributed. That is, by providing the hemispherical projection 28 at the branching position of the waveguide 14, the impedance matching of the microwave at the branching position is improved, and the microwave output from the magnetron 13 is reflected to the magnetron 13 side. Can be suppressed. Thereby, when the microwave generated in the magnetron 13 is guided to each shunt 18 through the waveguide 14, the microwave in the waveguide 14 is favorably sent to each shunt 18 (antenna portion 15 described later). Can be guided to. As a result, it is possible to prevent problems such as that the microwave reflected toward the magnetron 13 causes discharge in the vicinity of the antenna 29 of the magnetron 13 or the like.

  Each shunt 18 of the waveguide 14 is provided with an antenna portion 15 (microwave radiation means) that radiates the microwave guided by the waveguide 14 into the heating chamber 11. These two antenna portions 15 form a pair and are arranged on the left and right sides so as to be symmetrical in the width direction with respect to the branching position of the waveguide 14 (the projection 28 and further the central portion in the left-right direction of the heating chamber 11). ing. The antenna unit 15 includes a motor 19 and a rotating antenna 20 (see FIG. 4) as a rotating microwave radiation antenna. The motor 19 is attached to the shunt 18 from below. As shown in FIG. 4, the rotating shaft of the motor 19 is coupled to the rotating shaft 21 of the rotating antenna 20, and the rotating shaft 21 extends upward in the shunt 18 into the recess 16. The left and right rotating shafts 21 are arranged so as to be symmetrical in the width direction with respect to a branching position (a reference plane X described later) of the waveguide 14. The rotating antenna 20 is attached to the rotating shaft 21 in the recess 16. The rotary antenna 20 is in the form of an elongated rectangular thin plate in the drawing, and is attached to the rotary shaft 21 at a position off the center in the longitudinal direction. The rotating antenna 20 is not limited to the shape described above, and may be, for example, a substantially disk shape that protrudes horizontally and asymmetrically with respect to the rotating shaft 21. The rotating antenna 20 receives the driving force of the motor 19 and rotates along the lower surface of the bottom plate 6 around the rotating shaft 21.

  The microwaves guided to the respective shunts 18 (see FIG. 3) by the waveguide 14 reach the rotating antenna 20 via the rotating shaft 21 of the rotating antenna 20 and rotate in the pair of left and right antenna units 15. 20 is emitted. Then, this microwave passes through the bottom plate 6 shown in FIG. 2 and is supplied into the heating chamber 11. The bottom plate 6 is formed of a material that transmits microwaves, such as a ceramic plate. Microwave operation is performed by radiating microwaves into the heating chamber 11 by the antenna unit 15, and the food to be cooked in the heating chamber 11 is cooked by microwave heating (dielectric heating). The pair of antenna portions 15 can be installed so as to radiate microwaves from the left and right side surfaces of the heating chamber 11, for example, but are provided on the left and right below the bottom plate 6 of the heating chamber 11 as in this embodiment. Therefore, microwave heating can be performed satisfactorily. Further, by using the rotating antenna 20, microwaves can be radiated and stirred almost uniformly into the heating chamber 11.

The rotating antenna 20 may be the rotating antennas 20A and 20B shown in FIG. 5 instead of the one shown in FIG.
Rotating antennas 20A and 20B shown in FIG. 5 are large flat antennas that are formed of thin metal plates and have the same planar shape. That is, each of the rotary antennas 20A and 20B includes a wide rectangular projecting portion 211 projecting from the rotation shaft 21 in a predetermined angular direction, a pair of narrow rectangular sub projecting portions 212 and 213 projecting on both sides thereof, and a rectangular shape. It has a semi-ring-shaped projecting portion 214 projecting in an angle direction opposite to the projecting direction of the assertion projecting portion 211, and a hook-shaped projecting portion 215 formed inside the semi-ring-shaped projecting portion 214.

By adopting such a large W antenna structure that includes a pair of large flat antennas on the left and right, the microwave oven 1 can be made to perform the following microwave heating.
First, as a diffusion mode, microwave heating is performed while rotating the two rotating antennas 20A and 20B in the opposite directions at a constant speed. In the diffusion mode, microwaves are diffused from the large W antennas 20A and 20B, and the microwaves are spread to every corner of the heating chamber 11, and cooking can be performed while suppressing uneven heating of food.

Further, as the concentrated mode, the rotation of the two rotary antennas 20A and 20B is stopped at the position shown in FIG. 5, and microwave heating is performed. The concentration mode is, for example, a speed heating mode that can satisfy the desire to quickly heat a bowl of rice or to quickly heat a dish.
The rectangular asserting portions 211 and 211 of the rotating antennas 20A and 20B are portions that radiate microwaves strongly. When the rotating antennas 20A and 20B are stopped at the position shown in FIG. Microwaves are emitted strongly to the center. Therefore, the food placed in the central portion of the heating chamber 11 can be quickly heated.

FIGS. 6A and 6B are image diagrams of microwave radiation in the diffusion mode and the concentrated mode. FIG. 6A shows the diffusion mode and FIG. 6B shows the concentration mode. By using the rotating antennas 20A and 20B, the diffusion mode and the concentration mode can be switched as necessary.
<Infrared sensor>
As shown in FIGS. 4 and 11, the infrared sensor 30 is attached to the upper surface of the back surface of the casing 4 (frame 12) so as to face the bottom plate 6 from above the back of the central portion in the left-right direction of the heating chamber 11. Yes. Also, corresponding to the infrared sensor 30, a detection window 31 is formed at the upper rear portion of the casing 4 as shown in FIG.

  As shown in FIG. 4, the infrared sensor 30 and the detection window 31 are located at the same distance from the two left and right antenna portions 15 (more specifically, the rotation axis 21 that is the rotation center of the rotation antenna 20). Located on X. Specifically, the reference plane X includes the center position Z of the line Y connecting the rotation centers of the left and right rotary antennas 20, and the reference plane X passes through the center of the casing 4 (frame 12) in the width direction. . In other words, the infrared sensor 30 and the detection window 31 are disposed at the symmetry center of the pair of antenna units 15.

  The infrared sensor 30 detects infrared rays generated from the food to be cooked in the heating chamber 11 through the detection window 31. Specifically, as shown in FIG. 11, the infrared sensor 30 has a plurality of (e.g., eight in this embodiment) visual fields 32 arranged in the heating chamber 11 continuously in the front-rear direction when viewed from the right side. More specifically, the infrared sensor 30 includes a plurality (eight in this embodiment) of infrared detection elements (not shown) having a visual field 32. The viewing angle θ of each field of view 32 is set equal. As will be described later, the infrared sensor 30 is provided so as to be able to swing left and right. At the home position (basic position), the left and right central portions of the bottom plate 6 are detected from the front end to the rear end by the eight visual fields 32. be able to. That is, when the infrared sensor 30 is at the basic position, the eight visual fields 32 are at the symmetry center (reference plane X shown in FIG. 4) of the pair of antenna units 15. The infrared sensor 30 is provided with a swing mechanism 87. By the swing mechanism 87, the infrared sensor 30 can swing from the basic position to the left and right about the swing shaft 33 extending in a direction inclined to the front side, and according to the swing of the infrared sensor 30. The plurality of visual fields 32 move left and right on the bottom plate 6. Thereby, the visual field 32 can detect almost the entire surface of the bottom plate 6 in the heating chamber 11. Therefore, the infrared sensor 30 faces the food to be cooked accommodated on the bottom plate 6 from above, and detects infrared rays generated from the surface of the food to be cooked to be heated in the visual field 32. Based on the detection result, a control unit (not shown) determines the current temperature of the food to be cooked. Thereby, the progress of cooking can be detected. In addition, as described above, the infrared sensor 30 has a detection visual field over almost the entire surface of the bottom plate 6 of the heating chamber 11, so that the cooking status of the stored food can be accurately detected. And a control part (not shown) controls the supply time of a microwave according to the present temperature of the food to be cooked. That is, the microwave heating time is automatically controlled.

  As described above and as schematically shown in FIG. 7A, the infrared sensor 30 is at a position (on the reference plane X) that is separated from the rotation center of the two rotary antennas 20 by an equal distance. . That is, the swing shaft 33 of the infrared sensor 30 and the reference plane X coincide. In other words, since the infrared sensor 30 is located at the center of symmetry of the pair of antenna units 15 described above, it can be said that the pair of antenna units 15 are disposed at positions symmetrical to the field of view 32 of the infrared sensor 30. In this case, when the infrared sensor 30 is swung equally to the left and right, the field of view 32 moves equally to the left and right so as to be symmetrical with respect to the reference plane X, and the size (in FIG. 7A). The range W) is equal on the left and right rotating antennas 20 side. That is, the infrared sensor 30 has a uniform visual field range for the pair of antenna units 15. Thereby, the infrared sensor 30 can accurately detect infrared rays without being biased to either side of the left and right rotating antennas 20. Therefore, the above-described control unit (not shown) enables accurate temperature determination of the food to be cooked, and a stable finish is achieved when the cooking status of microwave heating by the pair of antenna units 15 is automatically controlled. Thus, the cooking situation can be detected accurately. And since the infrared sensor 30 detects the cooking condition by moving the visual field 32 from the symmetrical center (the above-mentioned basic position) of the pair of antenna units 15 to the left and right, the cooking condition of the food that is microwave-heated is detected. It can be detected fairly, correctly and stably without variation depending on the position of the food.

  On the other hand, as shown in FIG. 7B, when the infrared sensor 30 is not located at a position (on the reference plane X) at an equal distance from the rotation center of the left and right rotating antennas 20, the infrared sensor 30 is Even if it is swung to the right, the field of view 32 does not move symmetrically with respect to the reference plane X, and the size (range W) differs between the left and right rotating antennas 20. FIG. 7B shows an example in which the infrared sensor 30 is shifted from the reference plane X to the right side. The range W of the field of view 32 is wide on the left rotating antenna 20 side, while the right rotating antenna is shown. On the 20th side, it becomes narrower and the detection accuracy is different (the left rotating antenna 20 has lower accuracy). For this reason, the infrared sensor 30 is biased on the left and right rotating antennas 20 side to detect infrared rays, and it is difficult to accurately detect infrared rays.

Moreover, as shown in FIG. 11, the infrared sensor 30 arrange | positions the infrared rays sensor 30 so that the baseplate 6 may be desired from the back upper surface of the heating chamber 11, and the infrared sensor 30 changes the cooking condition of the food accommodated in the heating chamber 11 from the upper direction. I can grasp it well. The upper rear surface of the heating chamber 11 is a position where it is difficult for the heated food to reach when the heated food is blown up, and the infrared sensor 30 is not easily contaminated with food.
<Heater>
Referring mainly to FIG. 11, heaters that generate radiant heat when energized are disposed above and behind heating chamber 11. The upper heater is referred to as an upper heater 22, and the rear heater is referred to as a rear heater 23. In the microwave oven 1, in addition to the above-described microwave operation, a heater operation (oven heating) is performed in which the food to be cooked is heated using heat generated by the upper heater 22 and the rear heater 23.

Referring to FIGS. 11 and 13, upper heater 22 is formed by sandwiching a nichrome wire (not shown) that generates heat when energized between two flat plates made of mica (mica). Yes. Since the upper heater 22 faces the food to be cooked in the heating chamber 11 from above, the upper surface of the food to be cooked can be burnt.
With reference to FIGS. 8 and 11, the rear heater 23 is built in the rear side wall of the frame 12. In other words, the rear side wall of the frame 12 has a double structure including an outer wall (not shown in FIG. 11) facing the outside and an inner wall 41 (wall surface) facing the heating chamber 11. It arrange | positions in the space (it is called the heating circulation chamber 74) between the outer wall and the inner wall 41 mentioned above. The heating circulation chamber 74 is adjacent to the heating chamber 11 from the rear side, and the heating chamber 11 and the heating circulation chamber 74 are partitioned by the inner wall 41. As shown in FIG. 8, the heating circulation chamber 74 is provided with a fan 35 in addition to the rear heater 23. The fan 35 is disposed at a substantially central position of the heating circulation chamber 74 in a front view. The fan 35 rotates in the counterclockwise direction when viewed from the front (see the arrow in the figure) around a rotation axis extending in the front-rear direction. The fan 35 has 16 blades along its periphery, and sends out air taken in from the center front to the surroundings with 16 blades. The rotation speed of the fan 35 is normal rotation, for example, about 2100 rpm.

  As shown in FIG. 9, the rear heater 23 includes, for example, a nichrome wire 36 as a heating element, a metal outer skin 37 covering the outer periphery of the nichrome wire 36, and an insulation filled between the nichrome wire 36 and the outer skin 37. This is a so-called sheathed heater including the powder 34. The rear heater 23 is further provided with heat radiation fins 38 protruding from the outer peripheral surface of the outer skin 37. The heat radiating fins 38 are formed of a material having high thermal conductivity, and project from the circumferential surface of the outer skin 37 so as to be spirally continuous over its length direction (axial direction). The radiating fins 38 are, for example, caulked against the outer skin 37. In this way, the radiating fins 38 can be easily created by forming the radiating fins 38 so as to protrude from the outer peripheral surface of the outer skin 37 in a spiral shape that is continuous in the axial direction of the outer skin 37. Further, the heater 23 can be easily formed after the heat radiation fins 38 are attached. When the nichrome wire 36 is energized, the nichrome wire 36 generates heat, and the heat is transmitted to the heat radiating fins 38 through the outer skin 37. The air around the radiation fin 38 is heated by the heat transmitted to the radiation fin 38. Since the rear heater 23 includes the heat radiation fins 38, the rear heater 23 efficiently releases heat with a surface area about eight times that of a normal sheathed heater (having no heat radiation fins).

  Referring to FIGS. 8, 10, and 11, rear heater 23 extends to surround fan 35 in a front view. Specifically, the rear heater 23 extends upward from the vicinity of the lower left end portion of the inner wall 41 as a start position 39, bends with a relatively large curvature, then extends to the right, and then bends with a relatively small curvature and then downwards. And bent to a left side after bending with a relatively small curvature, and then bent to draw an inverted S-shape on the right side of the above-described start position 39 and then extended to a lower end position 40. As described above, the rear heater 23 is densely arranged (the arrangement density is higher than that of the other part) in the vicinity of the start position 39 and the end position 40, and the heat generation amount is larger in the dense part than in the other part. The fan 35 is disposed inside the heater 23 after being bent.

  As shown in FIG. 8, the inner wall 41 has a large number of through holes 42 (blowing holes). Specifically, a plurality of through holes 42 are formed in each of the first position 43, the second position 44, the third position 45, the fourth position 46, the fifth position 47, and the sixth position 48 in the inner wall 41. The first position 43 is a position facing the center of the fan 35. The second position 44 is a position facing the above-described dense portion of the rear heater 23 and is on the left side of the first position 43. The third position 45, the fourth position 46, and the fifth position 47 are positions facing the upper portion, the right portion, and the lower portion of the rear heater 23 from the fan 35, respectively. The sixth position 48 is near the upper left end portion of the inner wall 41.

  As described above, when the fan 35 rotates in the counterclockwise direction when viewed from the front (see the arrow in the drawing), the air in the heating chamber 11 is taken into the heating circulation chamber 74 through the through hole 42 at the first position 43. It is. The taken-in air is discharged radially from the center of the fan 35 to the surrounding rear heater 23 and heated by the rear heater 23 in the heating circulation chamber 74 while flowing around the fan 35 in a counterclockwise direction when viewed from the front. Is done. Specifically, the air discharged to the rear heater 23 by the fan 35 passes through the outer skin 37 and the heat radiating fins 38. By having the radiation fin 38, compared with the case of only the outer skin 37, the contact area with the passing air increases, and the air is efficiently heated. The heated air (heated air) is heated by the fan 35 through the through holes 42 in the second position 44, the third position 45, the fourth position 46, the fifth position 47, and the sixth position 48. The food to be cooked in the heating chamber 11 is heated. Thus, the air in the heating chamber 11 is heated while being circulated between the heating chamber 11 and the heating circulation chamber 74 by the fan 35 and the rear heater 23, and the food to be cooked in the heating chamber 11 is heated by this air. Heated. For example, when a plurality of square dishes 25 (see FIG. 18) are arranged in the vertical direction, even if only the upper heater 22 (see FIG. 4) is driven, only the food to be cooked in the square dish 25 at the uppermost position is sufficient. Cannot be heated. This is because it is difficult for the heat of the upper heater 22 to reach the square plate 25 below the square plate 25 at the uppermost position. On the other hand, by heating and circulating air as in the present embodiment, heat can be delivered to all the cooked foods of the plurality of square dishes 25, and these cooked foods can be sufficiently heated. . The post heater 23 that heats and circulates air is called a convection heater. And as above-mentioned, when taking in the air of the heating chamber 11 to the heating circulation chamber 74, heating the taken-in air and sending it out to the heating chamber 11, the back heater 23 was equipped with the radiation fin 38 (refer FIG. 9). Since it is a sheathed heater, the heating efficiency of the rear heater 23 is extremely good, and high-temperature air can be sent to the heating chamber 11. Therefore, food can be cooked at a stretch with high output, and the original deliciousness of the food can be brought out. In addition, cooking time can be shortened. Further, by providing the radiation fins 38, the temperature of the surface of the rear heater 23 (outer skin 37) can be prevented from being overheated, and the life of the rear heater 23 itself can be extended.

  Here, in the rear heater 23, the air heated in the above-described dense portion (in the vicinity of the start position 39 and the end position 40) has a higher temperature than the air heated in other portions, and as described above, It flows in the counterclockwise direction and is blown out to the lower part of the heating chamber 11 through the through hole 42 (specific blowing hole) at the fifth position 47. In other words, a dense portion of the rear heater 23 is disposed in the air flow path 85 toward the through hole 42 at the fifth position 47 in the heating circulation chamber 74. Thereby, the hot air sent out from the through-hole 42 of the 5th position 47 to the lower part (bottom plate 6) of the heating chamber 11 among the air heated by the back heater 23 can be made into especially high temperature. Therefore, the food to be cooked placed on the bottom plate 6 can be surely heated, and the food to be cooked placed at a position floating from the bottom plate 6 by being placed on the square plate 25 (see FIG. 18). When heating food from the lower side (oven heating), the lower fire effect can be enhanced.

  Further, as shown in FIG. 11, it is desirable that the rear heater 23 be provided in a state in which the radiating fins 38 are in contact with the inner wall 41. As a result, the heat of the rear heater 23 not only heats the air passing therethrough but also heats the inner wall 41 of the heating chamber 11 through the radiation fins 38. The temperature can be increased, and good cooking can be achieved in a short time.

The above-described configuration including the rear heater 23 with the radiation fins 38 of the heating circulation chamber 74 and the large fan 35 having a large number of blades can realize high-power oven cooking and can be referred to as a jet heat engine.
The wall surfaces of the heating chamber 11 and the heating circulation chamber 74 excluding the inner wall 41 are preferably formed of, for example, an air layer, a heat insulating plate, a heat insulating material, and a multilayer heat insulating steel plate sandwiching the heat insulating plate. The heat inside can be confined to achieve smoother high-heat cooking.

Moreover, the process (preheating process) which heats the inside of the heating chamber 11 previously is normally implemented prior to the cooking process of to-be-cooked food. In the preheating step, the rotational speed of the fan 35 shown in FIG. 8 is set lower than the normal rotational speed (about 2100 rpm) described above.
In the microwave oven 1, as shown in FIG. 12A, the control unit 17 (fan control means) is electrically connected to each of the operation panel 10, the fan 35 and the rear heater 23. The control unit 17 drives the fan 35 and the rear heater 23 in response to a preheating process execution command by operating the operation panel 10.

In the preheating process, as shown in FIG. 12B, the control unit 17 determines whether or not to perform the preheating process according to the operation of the operation panel 10 (step S1). When the preheating process is performed (YES in step S1), the control unit 17 energizes the rear heater 23 and rotates the fan 35 at a low speed of, for example, about 900 rpm (step S2). Thus, in the preheating step, the circulating speed of the heated air can be made relatively low by making the rotational speed of the fan 35 relatively low. Therefore, higher-temperature heated air is slowly supplied into the heating chamber 11 and stays in the heating chamber 11, and the heating chamber 11 can be warmed in a short time. Therefore, the preheating time can be shortened. On the other hand, when the preheating process is not performed, for example, in the cooking process after the preheating process (NO in step S1), the rear heater 23 is energized and the fan 35 is rotated at the above-described normal rotation speed (about 2100 rpm) (step S3). ).
<Superheated steam generator>
As shown in FIG. 13, an overheated steam generation unit 51 of the overheated steam generation device 5 that generates overheated steam for cooking is disposed on the left outer side of the heating chamber 11. In the microwave oven 1, in addition to the above-described microwave operation and heater operation, a steam operation is performed in which the food to be cooked is heated by the superheated steam generated by the superheated steam generation device 5. By supplying superheated steam into the heating chamber 11 and heating the food to be cooked with superheated steam, the food to be cooked can be desalted and degreased. In addition, the temperature of normal steam is about 100 ° C., whereas the temperature of superheated steam is about 130 ° C. In the steam operation, the upper heater 22 and / or the rear heater 23 are interlocked to heat the overheated steam in the heating chamber 11 with the heat generated by these heaters, thereby adjusting the temperature of the overheated steam in the heating chamber 11. It can also be raised to 350 ° C to 400 ° C.

The superheated steam generator 5 includes a tank 49 (see FIG. 1), a pipe 50, a pump (not shown), and one superheated steam generation unit 51.
The tank 49 accommodates water and is detachably attached to the lower front portion of the casing 4 as a so-called cassette system as shown in FIG.
As shown in FIG. 13, the superheated steam generation unit 51 is attached to the outer surface of the left side wall of the frame 12. Further, the superheated steam generation unit 51 includes upper and lower injection nozzles. As shown in FIG. 14, the upper injection nozzle 52 and the lower injection nozzle 53 are arranged in two upper and lower stages on the inner surface 86 (section screen) of the left side wall. It appears in A plurality (three in this embodiment) of the upper injection nozzle 52 and the lower injection nozzle 53 are provided side by side in the front-rear direction. The upper injection nozzle 52 faces the heating chamber 11 from the inner surface 86 above the uppermost rail 24U, and the lower injection nozzle 53 is located between the uppermost rail 24U and the second rail 24M from the uppermost position. , The inside of the heating chamber 11 is faced from the inner surface 86. The upper injection nozzle 52 and the lower injection nozzle 53 will be described in detail later.

  Returning to FIG. 13, the superheated steam generation unit 51 and the tank 49 not shown in FIG. 13 are connected by a pipe 50. A pump (not shown) is provided in the middle of the pipe 50 (specifically, in the vicinity of the tank 49). When this pump is driven, water in the tank 49 is overheated via the pipe 50. It is supplied to the steam generation unit 51. This water is heated by the superheated steam generation unit 51 to become superheated steam, and is jetted into the heating chamber 11 from the upper jet nozzle 52 and the lower jet nozzle 53 shown in FIG. Here, as shown in FIG. 18, when the square plate 25 is held by the second left and right rails 24 </ b> M from the uppermost position and the wire mesh 7 is placed on the square plate 25, the flat portion 26 of the wire mesh 7 is The length of the leg portion 27 is set so as to be disposed between the upper injection nozzle 52 and the lower injection nozzle 53 in the vertical direction. As a result, the food to be cooked placed on the flat portion 26 is sandwiched from above and below by superheated steam (see the arrow in the figure) sprayed from each of the upper spray nozzle 52 and the lower spray nozzle 53. In this case, the desalting and degreasing effects described above can be promoted. As described above, the superheated steam generation unit 51 includes the upper injection nozzle 52 and the lower injection nozzle 53 in two stages, so that the superheated steam can be supplied into the heating chamber 11 in a three-dimensional manner. As a result, the heating chamber 11 can be filled with superheated steam relatively quickly, and the food can be multifacetedly provided with superheated steam, and the food to be cooked can be heated well, and the cooking time can be shortened. Can be achieved. The number of spray nozzles is not limited to two but may be three or more.

Next, the superheated steam generation unit 51 will be described in detail.
As shown in FIG. 15, the superheated steam generation unit 51 has a substantially rectangular thin plate shape in a right side view. As shown in FIGS. 16 and 17, the superheated steam generation unit 51 is divided into a main body 54, a left lid 55, and a right lid 56. The main body 54, the left lid 55, and the right lid 56 are metal bodies having good thermal conductivity, for example, die-cast with aluminum. A ceramic body may be used instead of the metal body. The superheated steam generation unit 51 includes a left lid 55 (first metal body), a main body 54 (second metal body), and a right lid 56 (third metal body), which are stacked in three layers in this order from the left. The main body 54 is arranged at the center.

  As shown in FIG. 16, a protrusion (referred to as a main body right protrusion 57) that protrudes to the right is provided at the center in the front-rear direction of the right side surface of the main body 54 having a substantially rectangular thin plate shape. The main body right ridge 57 has a rectangular shape in a right side view, and a recess (referred to as a main body right recess 58) is formed inside thereof. Three small holes (referred to as upper small holes 59) penetrating the main body 54 in the width direction are formed at the upper end of the main body right depression 58 side by side in the front-rear direction. The two front upper small holes 59 are adjacent to each other. Below the upper small hole 59, three small holes (referred to as lower small holes 60) penetrating the main body 54 in the width direction are formed side by side in the front-rear direction. The three lower small holes 60 are arranged at equal intervals. The main body right depression 58 is provided with a pipe extending rightward so as to surround each lower small hole 60. This tube is the above-described upper injection nozzle 52.

  As shown in FIG. 17, the left side surface of the main body 54 is provided with a ridge projecting leftward (referred to as a main body first left ridge 61). The main body first left ridge 61 has a convex shape protruding upward in a left side view, and a recess (referred to as a main body left recess 78) is formed inside thereof. The main body left recess 78 has a relatively large-capacity water storage portion 76 located below, and a steam ascending passage 77 that is connected to the upper side of the water storage portion 76 and has a narrow width in the front-rear direction (left-right direction in the left side view). Including. Further, on the left side surface of the main body 54, a protrusion (referred to as a main body second left protrusion 62) that protrudes to the left along the main body first left protrusion 61 is provided outside the main body first left protrusion 61. It has been. Between the main body first left protrusion 61 and the main body second left protrusion 62, a groove (referred to as a main body left groove 63) is formed along the main body first left protrusion 61 and the main body second left protrusion 62. ing. The upper small hole 59 and the lower small hole 60 described above are located at the upper end of the main body left recess 78. The main body left recess 78 is provided with a plurality of ribs protruding leftward. These ribs include inclined ribs 64 and vertical ribs 65. The inclined rib 64 extends slightly downward and below each lower small hole 60. The vertical rib 65 extends substantially along the vertical direction below the inclined rib 64.

  A heater 66 (common heater) is attached to the main body 54. The heaters 66 are two sheathed heaters that extend in the front-rear direction with an interval in the vertical direction, and are attached to the main body 54 so that the portions other than the end portions are embedded in the main body 54. For convenience of explanation, the upper side is referred to as an upper heater 66U and the lower side is referred to as a lower heater 66L. The upper heater 66U is positioned slightly below the lower small hole 60 (in the vicinity of the inclined rib 64 and the vertical rib 65), and the lower heater 66L is positioned at the lower end in the main body left recess 78 and in the main body right recess 58. , Located slightly below the center in the vertical direction (see FIG. 16). Each heater 66 generates heat when energized, and the periphery of each heater 66 is heated in the main body left recess 78 and the main body right recess 58 (see FIG. 16).

The left lid 55 is formed in a convex thin plate shape protruding upward in the left side view. A small hole (referred to as a left lid small hole 67) that penetrates the left lid 55 in the width direction is formed at substantially the center in the front-rear direction of the left lid 55. On the left side surface of the left lid 55, a pipe (referred to as a joint pipe 68) extending leftward is provided so as to surround the left lid small hole 67.
As shown in FIG. 16, a right ridge (inner surface) of the left lid 55 is provided with a ridge (referred to as a left lid ridge 69) that protrudes to the right along the entire periphery of the left lid 55. A depression (referred to as a left lid depression 79) is formed inside the left lid protrusion 69. The left lid small hole 67 is disposed in the left lid ridge 69.

  The right lid 56 is formed in a substantially rectangular thin plate shape when viewed from the right side. Three holes (referred to as right wall holes 70) penetrating the right lid 56 in the width direction are formed in the upper end portion of the right lid 56 at equal intervals in the front-rear direction. Further, three small holes (referred to as right wall small holes 83) penetrating the right lid 56 in the width direction are formed at the lower end portion of the right lid 56 at equal intervals in the front-rear direction. Further, the right lid 56 is provided with a pipe extending rightward so as to surround each right wall small hole 83. This pipe is the lower injection nozzle 53 described above.

  As shown in FIG. 17, the left side surface (inner surface) of the right lid 56 is provided with a ridge (referred to as a right lid first ridge 71) that protrudes to the left along the entire periphery of the right lid 56. Yes. Further, on the left side surface of the right lid 56, a ridge projecting to the left along the right lid first ridge 71 (referred to as the right lid second ridge 72) is provided inside the right lid first ridge 71. Is provided. Between the right lid first ridge 71 and the right lid second ridge 72, a groove along the right lid first ridge 71 and the right lid second ridge 72 (referred to as a right lid groove 73) is formed. ing. A recess (referred to as a right lid recess 80) is formed inside the second right protrusion 72 of the right lid. In the three right wall holes 70, the front right wall hole 70 is located at the front upper end of the right lid groove 73, and the rear right wall hole 70 is located at the rear upper end of the right lid groove 73, The central right wall hole 70 is located in the right lid recess 80. On the other hand, all the right wall small holes 83 are located in the right lid recess 80.

A left lid 55 and a right lid 56 are attached to the main body 54.
The left lid 55 is attached to the main body 54 from the left side. At this time, the left lid ridge 69 (see FIG. 16) is fitted in the main body left groove 63. Here, the space between the left lid ridge 69 and the main body left groove 63 is closed by a heat-resistant adhesive previously poured into the main body left groove 63, for example, an adhesive of silicon. Then, by connecting the screw portions 81 provided on the peripheral edges of the main body 54 and the left lid 55 with screws (not shown), the attachment of the left lid 55 to the main body 54 is completed. Of the screw portions 81, the two screw portions 81 near the center of the upper end of the left lid 55 and the main body 54 are fastened together with the two screw portions 81 at the upper end of the right lid 56. In this state, the main body left recess 78 and the left lid recess 79 (see FIG. 16) communicate with each other. Here, in the main body left recess 78 and the left lid recess 79 that are in communication with each other between the main body 54 and the left lid 55, the above-described water storage portion 76 is formed in a portion below the vertical rib 65, A steam ascending passage 77 (supply passage) having a narrow width (front and rear width) is formed in a portion above the vertical rib 65. The steam ascending path 77 extends upward from the water storage section 76. For convenience of explanation, the water reservoir 76 and the steam ascending path 77 are shown in the main body left depression 78. The left lid small hole 67 communicates with the water reservoir 76, and the upper small hole 59 and the lower small hole 60 communicate with the upper portion of the steam ascending path 77. It can be said that the upper injection nozzle 52 (see FIG. 16) corresponding to the lower small hole 60 is formed in the upper part of the steam ascending path 77.

  On the other hand, the right lid 56 is attached to the main body 54 from the right side. At this time, the main body right ridge 57 (see FIG. 16) is fitted into the right lid groove 73. Here, the gap between the main body right ridge 57 and the right lid groove 73 is closed by, for example, silicon adhesive previously poured into the right lid groove 73. Then, by connecting the screw portions 81 provided on the peripheral edges of the main body 54 and the right lid 56 with screws (not shown), the attachment of the right lid 56 to the main body 54 is completed. In this state, the main body right depression 58 (see FIG. 16) and the right lid depression 80 communicate with each other. Hereinafter, the main body right depression 58 and the right lid depression 80 in communication between the main body 54 and the right lid 56 are collectively referred to as a steam guide path 82 (supply path). For convenience of explanation, the steam guide path 82 is shown in the main body right depression 58 (see FIG. 16). Each upper injection nozzle 52 is inserted through the corresponding right wall hole 70 and exposed to the right side (see FIG. 15). As shown in FIG. 16, the upper small hole 59 communicates with the upper part of the steam guide path 82, and the right wall small hole 83 communicates with the lower part of the steam guide path 82. It can be said that the lower injection nozzle 53 corresponding to the right wall small hole 83 is formed in the lower part of the steam guide path 82. Further, the steam guide path 82 communicates with the upper part of the steam ascending path 77 (see FIG. 17) through the upper small hole 59. Since each heater 66 swells into the steam guide path 82, it can be said that the steam guide path 82 is disposed in proximity to each heater 66.

As described above, the superheated steam generation unit 51 is completed as shown in FIG. In addition, the pipe 50 (refer FIG. 13) mentioned above is attached to the joint pipe 68 shown in FIG.
In this state, the above-described pump (not shown) is driven to supply water in the tank 49 (see FIG. 1) to the superheated steam generation unit 51 via the pipe 50 (see FIG. 13).

  The water supplied to the superheated steam generation unit 51 passes through the left lid small hole 67, falls as water droplets, and is stored in the water storage unit 76. This water is heated by the lower heater 66L in the water reservoir 76 (specifically, heated by the water reservoir 76 heated by the lower heater 66L) and becomes steam, as shown by the arrows in the figure. The steam rising path 77 is raised while passing between the ribs 65 and between the inclined ribs 64 in order. At this time, the steam is further heated by the heat of the upper heater 66U radiated from the vertical ribs 65 and the inclined ribs 64 to become overheated steam. In the superheated steam rising to the upper part of the steam rising path 77, a part flows from the lower small hole 60 through the upper injection nozzle 52 (see FIG. 16) and is injected into the heating chamber 11 as described above (FIG. 18). reference).

  On the other hand, in the superheated steam that has risen to the upper part of the steam ascending path 77, the superheated steam other than the superheated steam that flows to the lower small hole 60 flows into the steam guide path 82 shown in FIG. It is guided downward (see the arrow in the figure) by the path 82. Here, as described above, since the steam guide path 82 is disposed in the vicinity of the heater 66, the overheated steam descending the steam guide path 82 sequentially passes through the upper heater 66U and the lower heater 66L. The heater 66 is reheated. Thereby, the temperature fall of this overheated steam can be suppressed. Even if the superheated steam is cooled and becomes steam or water droplets before reaching these heaters 66, they are heated by these heaters 66, so that overheated steam is generated again. Then, the reheated superheated steam flows from the right wall small hole 83 through the lower injection nozzle 53 and is injected into the heating chamber 11 as described above (see FIG. 18). As described above, the superheated steam generation unit 51 can maintain the superheated steam until it is ejected from the upper injection nozzle 52 and the lower injection nozzle 53.

Further, as described above, the main body 54 in which the heater 66 is embedded is formed of a material having good thermal conductivity. Therefore, the water storage section 76 and the steam ascending path 77 (see FIG. 17) formed between the left lid 55 and the main body 54 and the steam guide path 82 formed between the main body 54 and the right lid 56 are provided. On the other hand, the heat of the heater 66 can be supplied satisfactorily.
In the microwave oven 1, the number of parts can be reduced by supplying superheated steam to both the upper injection nozzle 52 and the lower injection nozzle 53 with one superheated steam generation unit 51. Further, in the superheated steam generating unit 51, the heater 66 has a steam rising path 77 (see FIG. 17) for supplying superheated steam to the upper injection nozzle 52, and a steam guide path 82 for supplying superheated steam to the lower injection nozzle 53. Since both are heated, the structure can be simplified. The heater 66 is composed of two heaters, an upper heater 66U and a lower heater 66L. However, the two heaters can be integrated by connecting them in a U-shape. In that case, the connecting portion of the two heaters may be disposed in the steam guide path 82.

As a modification, an overheated steam generation unit 51 shown in FIG. 19 may be used. In FIG. 19, parts that are the same as the parts described above are given the same reference numerals, and descriptions thereof are omitted.
In the overheated steam generation unit 51 according to the modification, the right lid 56 (see FIG. 17) is omitted, and instead, a pipe (referred to as a guide pipe 84) that is bent in a substantially S shape is provided. In the guide pipe 84, the straight portion is formed of a metal such as aluminum, copper, or stainless steel, and the bent portion is formed of silicon or the like. Of course, the guide pipe 84 may be entirely made of metal or may be entirely made of silicon. In each guide pipe 84, one end is connected to the corresponding upper small hole 59 (see FIG. 16), and the lower injection nozzle 53 is connected to the other end. Each guide pipe 84 is attached to the main body 54 so as to come into contact with the upper heater 66U and the lower heater 66L from the right side. Therefore, as described above, the superheated steam that has reached the upper small hole 59 (see FIG. 16) from the steam ascending passage 77 (see FIG. 17) flows through the guide pipe 84, and similarly to the above-described embodiment, the upper heater 66U and Reheated by the lower heater 66L.

  The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.

It is a front right perspective view of microwave oven 1 as a food cooking device concerning one embodiment of this invention. In FIG. 1, the state which opened the door 2 is shown. 2 is a bottom view of the microwave oven 1. FIG. It is a front upper side perspective view of the casing 4 in the state which removed the door 2 and the decorative board 3 (outer cover board). It is a top view of the recessed part 16 which is the bottom of the heating chamber 11, Comprising: It is a figure which shows arrangement | positioning and shape of rotating antenna 20A, 20B. FIG. 6A is an image view of microwave radiation in the diffusion mode, and FIG. 6B is an image view of microwave radiation in the concentrated mode. It is a schematic diagram for demonstrating a mode that the visual field 32 moves in the heating chamber 11 with the rocking | fluctuation of the infrared sensor 30 as a cooking condition detection means, Comprising: Fig.7 (a) applied the present Example. FIG. 7B shows a case where a comparative example is applied. It is a front view of casing 4 in the state where door 2 was removed. It is the figure which extracted and showed the back heater 23 partially. It is a photograph of a prototype showing the inside of the heating circulation chamber 74. It is right side sectional drawing of the casing 4 in the state which removed the door 2 and the decorative board 3 (outer cover board). FIG. 12A is a block diagram showing an electrical configuration related to the preheating process of the microwave oven 1, and FIG. 12B is a flowchart for explaining the preheating process. It is a front left perspective view of the casing 4 in the state which removed the door 2 and the decorative board 3 (outer cover board). It is a front right perspective view of casing 4 in the state where door 2 and decorative board 3 (outer cover board) were removed. It is a front right perspective view of the superheated steam generation unit 51. It is a disassembled perspective view of the superheated steam production | generation unit 51 shown in FIG. It is a disassembled perspective view of the superheated steam production | generation unit 51 seen from the front left side. It is the figure which added the square plate 25 and the metal-mesh 7 to FIG. It is a right view of the superheated steam production | generation unit 51 which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave oven 2 Door 6 Bottom plate 11 Heating chamber 13 Magnetron 14 Waveguide 15 Antenna part 18 Shunt 20 Rotating antenna 21 Rotating shaft 28 Protrusion 30 Infrared sensor 32 Field of view 87 Oscillation mechanism

Claims (7)

The front is opened and closed with a door, and a heating chamber for storing cooked food,
A pair of microwave radiating means provided at symmetrical positions with respect to the central portion in the left-right direction of the heating chamber, and for radiating microwaves into the heating chamber;
A cooking state detection means provided at a position facing the food to be cooked stored in the heating chamber from above, and provided at the center of symmetry of the pair of microwave radiation means,
Including a microwave oven.   2. The microwave oven according to claim 1, wherein the pair of microwave radiating means are provided on the left and right along the bottom surface of the heating chamber.   3. The microwave oven according to claim 1, wherein each of the pair of microwave radiating means includes a rotary microwave radiating antenna that rotates about a rotation axis.   The microwave oven according to any one of claims 1 to 3, wherein the cooking status detection means is provided so as to face the bottom surface from above the back of the central portion in the left-right direction of the heating chamber.   5. The microwave oven according to claim 4, wherein the cooking status detection means has a visual field for detecting substantially the entire bottom surface of the heating chamber. The cooking status detection means has a plurality of fields of view for detecting the center in the left-right direction of the bottom surface of the heating chamber from the front end to the rear end,
6. The microwave oven according to claim 5, further comprising a swinging mechanism that swings the cooking condition detecting means so that the plurality of fields of view move left and right on the bottom surface. A magnetron provided in the vicinity of the heating chamber;
A branch waveguide for guiding the microwave radiated from the magnetron into two shunts,
Each of the two shunts is provided with the microwave radiation means,
The microwave oven according to any one of claims 1 to 6, wherein a hemispherical protrusion that bulges into the branch waveguide is formed at a branch position of the branch waveguide.