JP6004281B2 - Microwave heating device - Google Patents

Description

  The present invention relates to a microwave heating apparatus that radiates microwaves to an object to be heated and performs dielectric heating, and more particularly, to a heating cooker that cooks food that is an object to be heated by induction heating.

  In a microwave heating apparatus, the basic configuration of a heating cooker using microwaves typified by a microwave oven is a heating chamber shielded so that microwaves do not leak outside, a magnetron that generates microwaves, and a magnetron And a waveguide for transmitting the microwave generated in the heating chamber to the heating chamber.

  In the heating cooker, regarding the components other than the heating chamber, the magnetron, and the waveguide, various configurations are used according to the method according to the purpose. For example, there are a lateral feeding method, a lower feeding method, an upper feeding method, a vertical feeding method, and the like depending on from which direction the microwave is incident on the heating chamber, and the configuration differs depending on these feeding methods. .

  In the case of a lateral feeding method in which microwaves are incident from the side surface of the heating chamber, the food itself that is the object to be heated needs to be rotated in the heating chamber so that the distribution of the microwaves is not biased. Thus, a so-called turntable method is used in the lateral feeding method. On the contrary, in the case of the lower power feeding method in which microwaves are incident from the bottom surface in the heating chamber, the upper power feeding method in which microwaves are incident from the ceiling wall surface, and the vertical power feeding method in which microwaves are incident from both the bottom surface and the ceiling wall surface Without moving the food that is the object to be heated, the antenna that is the power feeding unit provided at the coupling portion between the waveguide and the heating chamber is rotated to radiate the microwave. The so-called rotating antenna method for rotating the antenna in this way is used for the lower feeding method, the upper feeding method, and the vertical feeding method.

  In the microwave oven, what power supply method is selected is determined in consideration of not only the microwave oven function but also other functions such as an oven function, a grill function, and a steam function. Thus, when using the function of a microwave oven and another function together, it is necessary to provide a heater, a water tank, a steam generation mechanism, etc. other than the microwave electric power feeding structure, for example. For this reason, it is necessary to arrange | position each structure efficiently inside an apparatus (for example, refer patent document 1).

  In addition, when using, for example, an oven, a grill, and superheated steam, which is water vapor exceeding 100 ° C., in the heating cooker, the heating chamber becomes high temperature, so that the material for placing the food to be heated is heat resistant. Highly conductive dishes may be used. When a conductive dish is used in this manner, the microwave is reflected by the conductive dish, so that the microwave in the heating chamber is different from the case where a dielectric dish such as glass or ceramic that transmits microwaves is used. Wave distribution is different.

  Also, a conductor net may be used instead of the conductor dish. When a conductor net is used, microwaves pass when the mesh is increased to some extent compared to the wavelength, and therefore the microwave distribution in the heating chamber changes depending on the net shape.

  Furthermore, recently, the need for cooking in which the functions of a microwave oven and other functions cooperate with each other has increased. For example, when baking a large food or baking a frozen food, only the surface of the food is heated only by heating with the heater, so that the inside of the food may not be ignited. As such a cooker having only a heater, an oven toaster having only a heater as a heating source corresponds to this. In order to heat the inside of the food only with a heater using such an oven toaster, the heating power (output) is lowered and gradually heated by heat conduction at a low temperature for a long time so as not to burn the food surface. There is only a way to do it.

  On the other hand, by heating the object to be heated using a microwave oven that performs dielectric heating, the food as the object to be heated is a dielectric, so that microwaves can penetrate into the food and heat the food. Is possible. As described above, by using the microwave oven, it is possible to set fire inside the food in a short time. Therefore, by cooperating the function of the microwave oven that heats the inside of the food and the function of the heater that bakes the surface of the food, it becomes possible to bake large foods or frozen foods in a short time.

JP 58-181289 A

  However, when high-frequency heating is performed using microwaves in a conventional cooking device, when microwaves are not efficiently absorbed into food to be heated, the microwaves reflected in the heating chamber are guided from the power feeding unit to the waveguide. There is a problem that the magnetron returns to the magnetron through the self-heating and the magnetron self-heats.

  Furthermore, in the conventional cooking device, when performing heating heating using convection heat using hot air or radiant heat that burns the surface of food at the same time as microwave high frequency heating, it is affected by the heating chamber during high temperature heating. The magnetron, which is a microwave supply source, has a problem that the temperature rises during operation. In such a case, when the microwave radiated into the heating chamber is not absorbed by the food and the reflected wave reflected by the food is not configured to be suppressed from returning to the power supply unit, In addition, there is a problem that the temperature rise of the magnetron becomes more remarkable due to the self-heating of the magnetron.

  In a cooking device configured to be built in a kitchen as equipment, in particular, an operation panel is provided above the heating chamber in order to make the heating chamber as large as possible and make it easier for the user to operate. For this reason, it is demanded that the microwave power supply configuration and other configurations (for example, a heater drive circuit and a cooling configuration) be similarly mounted above the heating chamber in a compact manner. When configured in this manner, the microwave power supply configuration is disposed above the heating chamber that is at a high temperature, so that the magnetron is likely to receive heat from the heating chamber. In particular, when the magnetron itself is in contact with the wall surface of the heating chamber, or when the waveguide joined to the magnetron is in contact with the outer wall surface of the heating chamber ceiling and extends along the outer wall surface In this case, the influence of the heat of the heating chamber on the waveguide becomes very large. Therefore, in the case where the microwave power supply configuration and the heater power supply configuration coexist and the heating operation is performed at the same time, there is a problem that it is difficult to achieve both the prevention of the magnetron temperature rise and the downsizing of the apparatus. .

  FIG. 10 is a front cross-sectional view showing a schematic configuration when a heater power supply configuration having a heater is further provided in a cooking device in which a general microwave power feeding configuration is provided on the upper side of the heating chamber. In the conventional heating cooker shown in FIG. 10, a heating chamber 101 for dielectrically heating a food product 107 that is an object to be heated is provided inside a casing 100 that constitutes the appearance of the heating cooker. A heater 102 is provided at an upper and lower position inside the heating chamber 101. In addition, above the upper heater 102 and above the heating chamber 101, microwave feeding configurations such as a magnetron 103, a waveguide 104, a rotating antenna 105, and a motor 106 are disposed. In the conventional cooking device configured as described above, the microwave radiated from the rotating antenna 105 serving as the power feeding unit irradiates the food 107 serving as the object to be heated. In the microwave irradiated with the food 107, approximately 64% of the microwave converted to electric power is reflected on the interface between the air and the food 107 due to the difference in dielectric constant between the air and the food 107. The microwaves reflected in this way are directed from the food 107 to the direction of the rotary antenna 105 vertically above, and are received by the rotary antenna 105 having strong directivity in the vertical direction. As a result, the microwave of the reflected wave received by the rotating antenna 105 returns to the magnetron 103 via the waveguide 104, and the magnetron 103 self-heats. When the size of the food 107 is small, the number of microwaves radiated from the rotating antenna 105 reaches the bottom surface of the heating chamber 101 beyond the food 107. Therefore, almost all of the microwaves reaching the bottom surface of the heating chamber 101 are reflected toward the ceiling wall surface of the heating chamber 101, and the reflected waves are received by the rotating antenna 105 provided on the ceiling wall surface. The reflected wave received by the rotating antenna 105 was sent to the magnetron 103 via the waveguide 104, and the magnetron 103 was self-heating.

  Further, the conventional cooking device configured as described above has a structure in which heat generated in the heating chamber 101 is conducted through the waveguide 104 and is transmitted to the magnetron 103, and the magnetron 103 is easily heated. . As a result, in the conventional cooking device, the magnetron 103 is configured to easily receive heat from the heating chamber 101 in addition to the heat generated by its own operation, and the magnetron 103 has a problem that the temperature rises. Therefore, in the conventional cooking device, there was a problem that the magnetron 103 failed or its life was shortened. Further, in order to solve these problems, there is a problem that the output must be set low.

Furthermore, the conventional cooking device has a problem that the heating efficiency by the microwave is lowered due to the temperature rise of the magnetron 103.
Further, in the conventional cooking device, the microwave power feeding configuration is arranged in the space above the heating chamber 101, and the magnetron 103 is vertically connected to the upper side of the heating chamber 101 as shown in FIG. As the high temperature air rises, the magnetron 103 is more easily heated, and a considerably high space is required above the heating chamber 101. As a result, there has been a problem that the size of the housing 100 has to be large.

  The present invention achieves a compact microwave power supply arrangement disposed on the upper side of the heating chamber, provides a small microwave heating apparatus, and increases the temperature of the magnetron due to self-heating by using a power supply structure that hardly receives reflected waves. An object of the present invention is to provide a microwave heating apparatus that suppresses the above, extends the life of the magnetron, has high reliability without lowering the output, and has improved heating efficiency.

The microwave heating apparatus of the present invention is
A heating chamber for storing an object to be heated and performing high-frequency heating by irradiating the object to be heated with microwaves,
A microwave power feeding chamber formed to protrude upward from the ceiling wall surface of the heating chamber,
A microwave generating unit for generating microwaves for high-frequency heating the object to be heated in the heating chamber;
A waveguide that connects the power supply chamber and the microwave generator to transmit microwaves, and a coupling hole formed in a joint portion between the power supply chamber and the waveguide is provided in a vertical direction. A feeding unit having a vertical axis element formed and a flat element having a radiation surface that is joined to the vertical axis element and emits microwaves to the heating chamber;
At least a part of the radiation surface of the microwave radiation surface of the flat plate element is disposed at an angle with respect to the horizontal direction at a predetermined angle θ ,
The area of the radiation surface having the predetermined angle θ is configured to be 1/2 or more of the entire radiation surface in the flat plate element,
In the entire radiation surface of the flat element, the total length in the inclination direction of the radiation surface inclined by a predetermined angle θ with respect to the horizontal plane is Ly, and corresponds to the position where the object to be heated in the heating chamber is joined to the vertical axis element. When the height to the position of the radiation surface of the flat plate element is H,
An inclination angle θrad of the inclined radiation surface is set to an angle larger than Ly / 2 / H and smaller than Ly / H, and configured to reduce receiving of a reflected wave from the object to be heated by the power feeding unit. Has been .

  In the microwave heating apparatus of the present invention, the plate element of the power feeding unit is provided so that the microwave is radiated downward at a predetermined angle θ from the coupling hole of the power feeding chamber provided on the ceiling wall surface of the heating chamber. For this reason, even if a part of the radiated microwave is reflected at the boundary surface with the object to be heated, the reflected wave is reflected in a direction deviated from the power feeding portion by an angle θ relative to the vertical direction. . Therefore, receiving the reflected wave from the object to be heated at the power feeding unit is greatly reduced, and the reflected wave component returning to the microwave generating unit via the waveguide can be greatly suppressed. ing.

  According to the present invention, temperature rise in the microwave generation unit is prevented, the life of the microwave generation unit is extended, high reliability is achieved without lowering the output, and output efficiency is improved. It is possible to provide a microwave heating apparatus capable of

Front sectional drawing which shows the internal structure of the principal part in the heating cooker of Embodiment 1 which concerns on this invention. The perspective view which shows the waveguide and feed chamber in the heating cooker of Embodiment 1 which concerns on this invention. Sectional drawing which shows the principal part which shows the electric power feeding part and to-be-heated material in the heating cooker of Embodiment 1 which concerns on this invention. Front sectional drawing which shows the internal structure of the principal part in the heating cooker of Embodiment 2 which concerns on this invention. Side surface sectional drawing of the principal part in the heating cooker of Embodiment 2 which concerns on this invention. The perspective view which shows the waveguide and feed chamber in the heating cooker of Embodiment 2 which concerns on this invention. The rear view which shows the electric power feeding part, the heating part, etc. which were provided in the ceiling wall surface of the heating chamber in the heating cooker of Embodiment 2 which concerns on this invention. Main part sectional drawing which shows the electric power feeding part and to-be-heated material in the heating cooker of Embodiment 3 which concerns on this invention. Main part sectional drawing which shows the electric power feeding part and to-be-heated material of another structure in the heating cooker of Embodiment 3 which concerns on this invention. Front sectional view showing a general microwave power feeding configuration in a conventional cooking device

A microwave heating apparatus according to a first aspect of the present invention includes a heating chamber for storing an object to be heated and performing high-frequency heating by irradiating the object to be heated with microwaves,
A microwave power feeding chamber formed to protrude upward from the ceiling wall surface of the heating chamber,
A microwave generating unit for generating microwaves for high-frequency heating the object to be heated in the heating chamber;
A waveguide that connects the power supply chamber and the microwave generator to transmit microwaves, and a coupling hole formed in a joint portion between the power supply chamber and the waveguide is provided in a vertical direction. A feeding unit having a vertical axis element formed and a flat element having a radiation surface that is joined to the vertical axis element and emits microwaves to the heating chamber;
At least a part of the radiation surface of the microwave radiation surface of the flat plate element is disposed at an angle with respect to the horizontal direction at a predetermined angle θ ,
The area of the radiation surface having the predetermined angle θ is configured to be 1/2 or more of the entire radiation surface in the flat plate element,
In the entire radiation surface of the flat element, the total length in the inclination direction of the radiation surface inclined by a predetermined angle θ with respect to the horizontal plane is Ly, and corresponds to the position where the object to be heated in the heating chamber is joined to the vertical axis element. When the height to the position of the radiation surface of the flat plate element is H,
An inclination angle θrad of the inclined radiation surface is set to an angle larger than Ly / 2 / H and smaller than Ly / H, and configured to reduce receiving of a reflected wave from the object to be heated by the power feeding unit. Has been .

  In the microwave heating apparatus according to the first aspect of the present invention configured as described above, a coupling hole for supplying microwaves to a portion where the feeding chamber and the waveguide provided on the ceiling wall surface of the heating chamber are joined is provided. The flat plate element of the power feeding unit is provided so that the microwave is radiated downward from the coupling hole at a predetermined angle θ. For this reason, even if a part of the microwave radiated from the power feeding unit is reflected on the boundary surface with the object to be heated, the reflected wave is reflected in a direction whose angle with respect to the vertical direction is shifted from the power feeding unit by θ. Therefore, the reception of the reflected wave by the power feeding unit is reduced, and the reflected wave component returning to the microwave generating unit via the waveguide is suppressed. As a result, in the microwave heating apparatus according to the first aspect, it is possible to prevent a temperature increase in the microwave generation unit due to self-heating. The microwave heating apparatus according to the first aspect has a structure in which the waveguide is joined to the heating chamber via the power supply chamber, and the waveguide is disposed apart from the heating chamber. For this reason, even if the heating chamber is at a high temperature, the microwave generation unit is less susceptible to heat from the ceiling wall of the heating chamber, and the heat transmitted from the heating chamber through the waveguide to the microwave generation unit is greatly reduced. ing. For this reason, the microwave heating device according to the first aspect has a structure that can reliably prevent the temperature rise of the microwave generation unit. In the microwave heating apparatus of the first aspect, even if the microwave generation unit is a compact configuration provided above the heating chamber, the temperature increase of the microwave generation unit is suppressed, and the microwave generation unit The lifetime can be extended, and the output efficiency can be improved with high reliability while maintaining a high output without reducing the output of the microwave generator.

In the microwave heating apparatus of the first aspect configured as described above, the microwave radiated from the power feeding unit has a strong radiation directivity in a direction perpendicular to the radiation surface of the flat plate element, and is bent. Thus, the radiation plane set at the angle θ occupies more than half of the whole. For this reason, in the microwave heating apparatus of the first aspect, most of the microwaves radiated from the power feeding unit are radiated obliquely by an angle θ with respect to the vertical direction. Thus, the microwave radiated obliquely from the radiation surface of the flat plate element is reflected by the heated portion or the like in a direction shifted from the power feeding portion by the oblique amount. Therefore, in the microwave heating device of the first aspect, the power receiving unit receives the reflected wave, and the reflected wave component that returns to the microwave generating unit via the waveguide can be suppressed. It is possible to prevent a temperature rise in the microwave generation unit due to self-heating. As a result, the microwave heating apparatus according to the first aspect can extend the life of the microwave generation unit, eliminate the need for power-down setting of the microwave generation unit, and improve the output efficiency. Further, in the microwave heating apparatus of the first aspect configured as described above, since the inclination angle θrad of the inclined radiation surface in the flat plate element is larger than Ly / 2 / H (ly / 2 / H <θ), the flat plate The angle is set so that microwaves radiated with a strong radiation directivity in the vertical direction from the radiation surface of the element do not return to the power feeding section even if they are reflected near the bottom of the heating chamber by the object to be heated or the wall surface. In addition, since the inclination angle θrad of the inclined radiation surface in the flat plate element is smaller than Ly / H (θ <ly / H), the inclination angle is too large, and the microwave is generated near the bottom center of the heating chamber immediately below the vertical axis element. The formation of a non-radiated region is prevented, and the radiation angle is set to a suitable radiation angle that can prevent the central portion of the object to be heated from being heated in a donut shape (ring shape) without being sufficiently heated. Can do. Therefore, the microwave heating apparatus of the first aspect realizes microwave heating without heating unevenness and suppresses the reflected wave component that returns to the microwave generation unit, thereby preventing a temperature increase due to self-heating in the microwave generation unit. And both.

The microwave heating apparatus according to the second aspect of the present invention includes a high-temperature heating unit that heats an object to be heated with at least one of radiant heat or convection heat simultaneously with high-frequency heating in the heating chamber according to the first aspect, With
In the configuration in which the microwave generation unit and the waveguide are disposed above the heating chamber,
The waveguide has a horizontal line and a vertical part and has a transmission line bent at a right angle, the microwave generating part is horizontally connected to the vertical part, and the heating chamber is connected to the horizontal part. The power supply chamber provided on the ceiling wall surface of the antenna is connected via a coupling hole, and both the waveguide and the microwave generation unit are disposed apart from the heating chamber. In the microwave heating apparatus according to the second aspect configured as described above, an object to be heated is placed on a material having a radio wave shielding function such as a metal tray, and high-frequency heating and other heating are simultaneously used in combination. Also, the microwave can be supplied downward from the power supply chamber provided on the ceiling wall surface of the heating chamber. For this reason, the microwave heating device of the second aspect can reliably heat the object to be heated without microwaves being shielded. In the microwave heating apparatus of the second aspect, since the microwave is radiated obliquely with respect to the vertical direction from the radiation surface of the flat plate element of the power feeding unit, the reflected wave component returning to the microwave generation unit is suppressed. Therefore, temperature rise due to self-heating can be prevented. Furthermore, a power supply chamber is provided on the ceiling wall of the heating chamber, a waveguide bent at a right angle to the power supply chamber is connected, and both the waveguide and the microwave generator are separated from the ceiling wall of the heating chamber. Since the microwave heating apparatus according to the second aspect is arranged so that the microwave generation unit is not easily subjected to heat from the ceiling wall surface of the heating chamber during high-temperature heating, the microwave generation is performed from the heating chamber through the waveguide. Heat transmitted to the part is also reduced. For this reason, the microwave heating device according to the second aspect can reliably prevent the temperature of the microwave generator from rising. Thus, in the microwave heating apparatus of the second aspect, even in a compact configuration in which the microwave generation unit is provided above the heating chamber, heat transfer from the heating chamber to the microwave generation unit is reduced, The life of the wave generation unit can be extended, the power generation setting of the microwave generation unit is unnecessary, and the output efficiency can be improved. Furthermore, in the microwave heating apparatus of the second aspect, since the microwave generator, for example, a magnetron is horizontally connected horizontally to the vertical transmission path of the waveguide, the size in the height direction of the entire apparatus Can be made compact.

In the microwave heating apparatus according to the third aspect of the present invention, in particular, the flat element in either the first or second aspect may be constituted by a substantially circular flat plate having a diameter of approximately 62 mm. The microwave heating apparatus according to the third aspect configured as described above is a flat element adapted to a microwave heating wavelength for a microwave oven or the like, and the flat element can resonate reliably at the wavelength of the microwave. . The microwave heating apparatus according to the third aspect generates a unidirectional radiation pattern having a central axis of the beam in a direction perpendicular to the radiation surface on the radiation surface of the plate element. Microwaves from the surface are radiated at an angle θ with respect to the vertical direction. As a result, since the reflected wave travels in a direction that is shifted from the power supply unit by an angle θ of this diagonal portion, in the microwave heating apparatus of the third aspect, the power supply unit is prevented from receiving the reflected wave, Temperature rise due to self-heating in the microwave generator is prevented.

In the microwave heating apparatus according to the fourth aspect of the present invention, in particular, the vertical axis element is joined at a position where the feeding portion in the third aspect is eccentric from the center of the disk of the flat element, The vertical axis element may be configured to rotate. In the microwave heating apparatus of the fourth aspect configured as described above, microwaves can be uniformly stirred and radiated from the radiation surface of the flat plate element into the heating chamber.

In the microwave heating apparatus according to the fifth aspect of the present invention, in particular, the flat plate element according to the third or fourth aspect is bent on a straight line including a center line of a disk (a line having a center point of the disk). In the line, one radiation surface may be bent at a predetermined angle θ with respect to the other radiation surface. In the microwave heating apparatus of the fifth aspect configured as described above, a large amount of microwaves that are inclined at an angle θ with respect to the vertical direction from the radiation surface of the flat plate element can be radiated into the heating chamber. it can.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to a microwave heating apparatus of the invention will be described with reference to the accompanying drawings. In the microwave heating apparatus of the following embodiment, a description will be given using a heating cooker. However, the heating cooker is an example, and the microwave heating apparatus of the present invention is not limited to the heating cooker. And a heating device using dielectric heating which is high frequency heating, a drying device, a heating device for ceramics, a garbage processing machine, or a semiconductor manufacturing device. Therefore, the present invention is not limited to the specific configurations of the following embodiments, but includes configurations based on the same technical idea.

(Embodiment 1)
As Embodiment 1 which concerns on this invention, the heating cooker in a microwave heating apparatus is demonstrated. In each of the following embodiments, a microwave oven including at least one heater will be described as an example of the heating means of the heating cooker.

  FIG. 1 is a front cross-sectional view showing an internal configuration of a main part in a heating cooker as a microwave heating apparatus according to Embodiment 1 of the present invention. In the heating cooker shown in FIG. 1, a heating chamber 11 for dielectrically heating (high-frequency heating) a food 15 that is an object to be heated is provided inside a casing 10 that forms the appearance of the cooking device. That is, in the heating chamber 11, the food 15 that is the object to be heated is stored, microwaves are emitted to the food 15, and high-frequency heating is performed. Two upper heaters 12 and a lower heater 13 which are radiant heating portions as high temperature heating portions for raising the temperature in the heating chamber are provided inside the heating chamber 11 formed of a steel plate whose surface is enameled. ing. One upper heater 12 is arranged on the ceiling wall side (upper side) of the heating chamber 11, and the other lower heater 13 is arranged on the bottom wall side (lower side) of the heating chamber 11. Inside the heating chamber 11, a grill 14 formed by combining stainless steel rods vertically and horizontally and welding is provided. The grill 14 is configured to be mounted at a plurality of desired positions in the heating chamber 11. The food 15 that is an object to be heated placed on the grill 14 is sandwiched between the upper heater 12 and the lower heater 13 and radiantly heated from above and below. The corners of the connecting portions between the wall surfaces constituting the heating chamber 11 are formed by curved surfaces. The entire bottom wall of the heating chamber 11 is formed in a curved shape having a large radius of curvature.

  In addition, in the heating cooker of Embodiment 1, although the wall surface of the heating chamber 11 demonstrates with the example formed with the steel plate which performed the enamel coating, it forms with the steel plate which applied the coating which has another heat resistance. May be. Further, the wall material may be stainless steel or PCM steel plate (Pre-coated metal). In the first embodiment, the grill 14 is formed by combining stainless steel rods, but can also be formed by using a steel material or the like subjected to plating.

  As shown in FIG. 1, a power supply chamber 24 is provided near the center of the ceiling wall surface of the heating chamber 11. Inside the feeding chamber 24, a feeding unit 22 of a rotating antenna as a radio wave stirring unit is arranged. The wall surface of the power supply chamber 24 is made of a material that reflects the microwave radiated from the power supply unit 22, and has a shielding structure so that the microwave does not leak outside the power supply chamber 24. The feeding portion 22 of the rotating antenna is provided in the waveguide 21 so as to be led out from a feeding port 25 which is a coupling hole. The waveguide 21 transmits the microwave from the magnetron 16 that is the microwave generation unit to the power supply unit 22. The magnetron 16 generates microwaves for high-frequency heating of the food 15 that is the object to be heated in the heating chamber 11. The microwave transmitted to the power feeding unit 22 is radiated into the heating chamber 11. The magnetron 16 is disposed at the right end (see FIG. 1) of the waveguide 21 disposed on the upper side of the heating chamber 11, and the magnetron output unit 44 that is an oscillation antenna of the magnetron 16 with respect to the waveguide 21. Is inserted sideways (horizontal direction).

  In the heating cooker according to the first embodiment configured as described above, one heating means has a dielectric heating section using microwaves, and the other heating means is high-temperature heating by radiation from the upper heater 12 and the lower heater 13. It has a radiation heating part as a part. Thus, the heating cooker of Embodiment 1 can perform desired cooking with respect to the foodstuff 15 which is the to-be-heated object in the heating chamber 11 by using together a dielectric heating part and a radiation heating part. It is a configuration.

  In addition, in the heating cooker of Embodiment 1, it demonstrates by the structure which has the dielectric heating part by a microwave as one heating means, and has the radiation heating part by the upper heater 12 and the lower heater 13 as another heating means. However, in the cooking device, instead of a high-temperature heating unit such as a radiant heating unit, a convection heating unit that performs cooking by circulating hot air in the heating chamber may be provided. As this convection heating unit, a circulation fan and a circulation heater are provided on the back side of the heating chamber, and the air in the heating chamber is heated to a high temperature and circulated. Of course, the cooking device may be configured to perform cooking by providing three heating units, a dielectric heating unit, a radiation heating unit, and a convection heating unit.

  The upper heater 12 and the lower heater 13 which are radiant heating parts in the heating cooker of Embodiment 1 are configured by sealing a heating wire together with a filler in a metal pipe. An upper heater thermocouple 17 that contacts the surface of the upper heater 12 is provided in the heating chamber 11. The upper heater thermocouple 17 is covered with a metal tube so as not to be affected by the microwave radiated from the power supply unit 22, and functions as a temperature detection unit of the upper heater 12. Further, a lower heater thermocouple 18 that contacts the surface of the lower heater 13 is provided in the heating chamber 11, and has the same configuration as the upper heater thermocouple 17. The lower heater thermocouple 18 functions as temperature detection means for the lower heater 13. A thermistor 19 is fixed to the wall surface of the heating chamber 11 as temperature detecting means in the heating chamber. The upper heater thermocouple 17, the lower heater thermocouple 18, and the thermistor 19 are electrically connected to a control unit 20 that is a control means. The control unit 20 controls the energization amount to the upper heater 12 and the lower heater 13 based on detection signals from the upper heater thermocouple 17, the lower heater thermocouple 18, and the thermistor 19. As described above, in the heating cooker according to the first embodiment, the heating control for the heating chamber 11 is controlled with high accuracy so that the heating amount becomes the set temperature.

  Inside the heating chamber 11, the upper heater 12 of the radiant heating section that heats the food 15 that is the object to be heated by radiant heat from above is disposed in a region other than directly below the power supply chamber 24. That is, the upper heater 12 is not directly irradiated by the microwave radiated from the power feeding unit 22 that is the rotating antenna in the power feeding chamber 24, and the food 15 that is the object to be heated is directly irradiated. .

  The waveguide 21 provided on the upper side of the heating chamber 11 includes a horizontal portion 42 extending in the horizontal direction and a vertical portion 43 extending in the vertical direction. That is, the waveguide 21 is an L-shaped internal passage (transmission) bent at a right angle by a horizontal transmission path (42) formed by the horizontal section 42 and a vertical transmission path (43) formed by the vertical section 43. Road). The magnetron 16 that is a microwave generation unit is inserted and connected to the vertical portion 43 of the waveguide 21 so that the magnetron output unit 44 that is an oscillation antenna is introduced in the horizontal direction. Accordingly, since the magnetron 16 is connected laterally (horizontal connection) with respect to the waveguide 21, the vertical height dimension is such that the magnetron 16 is connected vertically to the waveguide 21 (vertical connection: This is shorter than the case of FIG.

  As described above, the feeding port 25 formed in the horizontal portion 42 (horizontal transmission path) of the waveguide 21 having the L-shaped internal passage (transmission path) is provided with the feeding section 22 that is a rotating antenna. Yes. The power feeding unit 22 includes a flat plate element 22a and a vertical axis element 22b. The vertical axis element 22 b of the power feeding unit 22 is connected to the motor 23. The vertical axis element 22b is rotated by driving the motor 23, and the flat plate element 22a is rotated. The power feeding unit 22 is coupled to the horizontal transmission path (42) of the waveguide 21, and the microwave transmitted through the waveguide 21 is stirred and radiated into the heating chamber 11 by the flat plate element 22 a of the power feeding unit 22.

  Near the center of the ceiling wall surface of the heating chamber 11, a dome-shaped power supply chamber 24 that houses the rotating flat plate element 22 a is provided. The power supply chamber 24 has a shape in which a lower end portion extends in a circular shape, and has a truncated cone shape. The power supply chamber 24 is formed in a truncated cone shape by projecting the ceiling wall surface of the heating chamber 11 outward by drawing. The feeding port 25 formed on the lower surface of the horizontal portion 42 of the waveguide 21 is connected to an opening formed at the upper end of the feeding chamber 24 and functions as a coupling hole. The connecting portion between the power supply unit 22 and the power supply unit 22 has a predetermined diameter as a power supply port. As described above, the power supply chamber 24 is provided on the ceiling wall surface of the heating chamber 11 and is configured to reflect the microwave radiated from the flat plate element 22a in the lateral direction (substantially horizontal direction). The flat element 22a is set to resonate at the wavelength of the microwave used and to generate a unidirectional radiation pattern having a central axis of the beam in a direction perpendicular to the radiation surface of the flat element 22a. If even a slight amount of microwave is radiated from the flat plate element 22a in the horizontal direction, it is reflected on the wall surface of the power supply chamber 24. In addition, the power supply chamber 24 is open at the lower end portion of the power supply chamber 24 so that the microwave from the flat plate element 22 a is radiated into the heating chamber 11.

  As shown in FIG. 1, a cover 27 is provided on the ceiling wall surface of the heating chamber 11 at the opening that is the lower end of the power supply chamber 24. The cover 27 is made of mica and is provided so that dirt or the like scattered from the food in the heating chamber 11 does not adhere to the flat plate element 22a of the power supply unit 22 or the like. The cover 27 is detachably attached to an insulator hook 26 provided on the ceiling wall surface of the heating chamber 11. The cover 27 has been described with an example using mica, which is a low-loss dielectric material. However, the cover 27 is not limited to mica, and the same effect can be obtained by using a material such as ceramic or glass.

  The upper heater 12 provided at the upper part in the heating chamber 11 is disposed so as not to be directly heated by the microwaves from the power supply unit 22 and directly below the opening portion serving as the lower end of the power supply chamber 24. Since the upper heater 12 is arranged so as to bypass the opening portion of the power supply chamber 24 as described above, a gap portion 28 is formed in the central portion of the upper heater 12. Therefore, the microwave M (see FIG. 1) radiated directly from the power supply unit 22 toward the food 15 is not hindered by the upper heater 12. Thus, in the heating cooker of Embodiment 1, the microwave M radiated | emitted from the electric power feeding part 22 does not heat the upper heater 12 directly, loss is prevented, and improvement of a heating efficiency is achieved. It has been.

  FIG. 2 is a perspective view showing the waveguide 21 and the power feeding chamber 24 in the heating cooker according to the first embodiment. As shown in FIG. 2, the waveguide 21 has a horizontal portion 42 that forms a horizontal transmission path and a vertical portion 43 that forms a vertical transmission path, and an internal passage serving as a transmission path is L-shaped. It has a bent shape that is bent at a right angle. That is, the extending direction (horizontal direction) of the horizontal transmission path (42) and the extending direction (vertical direction) of the vertical transmission path (43) are orthogonal to each other. As described above, the waveguide 21 has the horizontal transmission path (42) and the vertical transmission path (43) bent at right angles, and the magnetron 16 serving as the microwave generation unit is horizontally disposed on the vertical transmission path (43). They are connected to transmit the microwave from the magnetron 16 to the horizontal transmission path (42).

  In the first embodiment, when the horizontal transmission distance from the bent position C (see FIG. 2) at the connection portion between the horizontal portion 42 and the vertical portion 43 to the center of the power supply port 25 is Lh (see FIG. 2), In the first embodiment, the distance Lh is set to about 135 mm. The horizontal transmission distance Lh is a horizontal distance along the extending direction (left and right direction in FIG. 1) of the horizontal transmission path from the bending position C in the transmission path in the waveguide 21 to the center of the power supply port 25. It is.

  The width a of the internal passage that is the transmission path of the waveguide 21 is about 80 mm, and the height b of the internal passage of the horizontal portion 42 of the waveguide 21 is about 16 mm. The width a of the internal passage and the height b of the internal passage in the horizontal portion 42 indicate the dimensions of the transmission path on the inner surface side of the waveguide 21.

  As described above, the magnetron 16 is fixed horizontally and horizontally with respect to the vertical portion 43 of the waveguide 21. That is, the magnetron output portion 44 that is an oscillation antenna of the magnetron 16 is inserted and mounted laterally into the opening 29 formed in the side wall (right side wall) of the vertical portion 43 of the waveguide 21. In the waveguide 21, if the vertical transmission distance (length in the vertical direction) from the bending position C to the center of the magnetron output portion 44 of the magnetron 16 is Lv (see FIG. 2), the vertical transmission distance Lv in the first embodiment. Is set to about 15 mm.

  In the cooking device of the first embodiment, the magnetron 16 having an oscillation frequency of about 2450 MHz is used. For this reason, when the guide wavelength in the waveguide 21 having the internal passage width a of about 80 mm is λg, λg is about 190 mm and the half-wavelength (λg / 2) is about 95 mm (λg / 2 = 95 mm). Therefore, in the configuration of the waveguide 21 in the heating cooker according to the first embodiment, the horizontal transmission distance Lh (about 135 mm), which is the substantial transmission path length in the horizontal portion 42, is a half wavelength (λg / 2 = 95 mm). ) Longer than (Lh> λg / 2). Further, the vertical transmission distance Lv (about 15 mm), which is a substantial transmission path length in the vertical portion 43, is configured to be shorter than a quarter wavelength (λg / 4 = 47.5 mm) (Lv <λg / 4). ing.

  FIG. 3 is a cross-sectional view of a main part showing the power feeding unit 22 and the object to be heated 15 in the heating cooker according to the first embodiment. As shown in FIG. 3, the flat plate element 22a of the power feeding unit 22 that stirs and radiates the microwave transmitted from the waveguide 21 by rotation thereof is made of metal, has a thickness of 1 mm, and a diameter of 62 mm. The disk has a shape bent by an angle of 10 ° along a folding line including a center line of the disk (a line having the center point of the disk). The vertical axis element 22b that transmits the rotation of the motor 23 to the flat plate element 22a is connected to a position that is eccentric about 12 mm from the center of the disk in the flat plate element 22a. Therefore, the radiation surface of one semicircular part of the flat plate element 22a is connected to the vertical axis element 22b and arranged in the horizontal direction, and the radiation surface of the remaining semicircular part is bent from the horizontal direction to be a predetermined angle θ (θ = 10 °) so as to face downward. In addition, although the position of the fold line of the flat plate element 22a in Embodiment 1 will be described with a configuration in which the fold line is bent along a straight line including the center line of the disk, the present invention is not limited to this configuration, The line may not include the center line of the disc. Therefore, in the microwave heating apparatus of the present invention, at least a part of the radiation surface of the plate element microwave radiation surface is bent at a predetermined angle θ with respect to the horizontal direction. The area of the radiating surface that has been bent is only required to be ½ or more of the entire radiating surface of the flat plate element.

  As described above, the flat plate element 22a has two regions of the horizontal plane portion Ah disposed in the horizontal direction by the fold line and the skew plane portion As that is inclined downward from the fold line by a predetermined angle θ with respect to the horizontal plane. It is divided into. The radiation surface of the oblique surface portion As is set to be the same as the radiation surface of the horizontal surface portion Ah or wider than the radiation surface of the horizontal surface portion Ah (As ≧ Ah). In the heating cooker according to the first embodiment, the line (Y), which is included in the oblique surface portion As of the flat plate element 22a, is perpendicular to the fold line by a fold angle (θ = 10 °) with respect to the horizontal plane portion Ah ( X) from below. When a bending angle (θ = 10 °), which is a predetermined angle, is expressed by an arc method (radian), θ≈0.175 rad. Since sin θ (≈0.174) at this time has a small angle (θ = 10 °), it is almost equal to θ rad. Therefore, the length (Ly) in the Y direction perpendicular to the folding line in the flat plate element 22a which is a disc having a diameter of 62 mm may be considered to be about 62 mm.

  In the heating chamber 11, when the height from the surface of the food 15 to the position of the radiation surface of the horizontal surface portion Ah of the flat plate element 22a facing the position joined to the vertical axis element 22b is H, In the heating cooker of form 1, H is about 330 mm. Therefore, since the skew angle θrad of the skew surface portion As of the flat plate element 22a is about 0.175, it is set to an angle larger than Ly / 2 / H≈0.094 and smaller than Ly / H≈0.188. (Ly / 2 / H <θrad <Ly / H).

  In the vertical axis element 22b, the portion on the motor 23 side is made of fluororesin, and the portion on the flat plate element 22a side is made of metal. The metal portion in the vertical axis element 22b includes a portion that enters the inside of the waveguide 21 and a portion that protrudes toward the feeding chamber 24 through the feeding port 25 of the waveguide 21. In addition, the gap between the metal portion and the power supply port 25 in the vertical axis element 22b is ensured by a distance of 5 mm or more.

  Next, the operation and action of the heating cooker according to Embodiment 1 configured as described above will be described.

  In the case of a circular flat plate element as in the first embodiment, the resonance frequency excited in the fundamental mode can be obtained using c = 0.58 × (wavelength) where c is the diameter of the flat plate element. Are known. However, since the resonance frequency including the vertical axis element 22b varies depending on the length and diameter of the vertical axis element 22b, the position on the flat plate element 22a to which the vertical axis element 22b is joined, the accurate resonance frequency has these dimensions and shapes. It is finally decided including.

  Therefore, in the heating cooker according to the first embodiment configured as described above, the flat plate element 22a having a diameter of approximately 62 mm resonates, and the horizontal plane portion Ah and the oblique plane portion of the flat plate element 22a are bent by this resonance current. A unidirectional radiation pattern is generated having the central axis of the beam in a direction perpendicular to the respective radiation surface of As. A microwave radiated with a strong radiation directivity from the radiation surface of the oblique surface portion As inclined downward by a predetermined angle θ with respect to the horizontal direction is radiated at an angle θ with respect to the vertical direction. .

  In general, the food 15 has a high moisture content and may be considered to be almost equivalent to water in terms of microwaves. Since the relative permittivity of water is about 80, the portion of the microwave incident perpendicularly to the food 15 that is transmitted and absorbed in the food is about 36 in terms of electric power due to the difference from the dielectric constant with air. %, And the remaining 64% is reflected at the interface between the air and the food 15.

  As described above, a part of the microwave radiated from the flat plate element 22 a obliquely by the angle θ with respect to the vertical direction is reflected at the boundary surface with the food 15. This reflected wave is reflected in a direction deviated from the antenna as the power feeding unit 22 by an angle θ with respect to the vertical direction. Since the inclination angle θrad is larger than Ly / 2 / H (Ly / 2 / H <θrad), ideally, the distance Ly from the radiation surface of the plate element 22a on the food 15 while the microwave travels the distance H. Reflected at a point deviated by / 2, and deviated by a distance Ly / 2 while the reflected wave again travels a distance H upward. Therefore, since the flat element 22a does not exist at the position where the reflected wave arrives, in the cooking device of the first embodiment, the reflected wave from the food 15 is prevented from being received by the antenna.

  As described above, in the heating cooker of the first embodiment, the feeding port 25 which is a coupling hole for connecting the waveguide 21 to the ceiling wall surface of the heating chamber 11 and supplying microwaves is provided, and this coupling hole portion The flat plate element 22a is arranged so that the microwave is radiated downward at a predetermined angle θ. For this reason, a part of the radiated microwave is reflected at the boundary surface with the food 15 that is the object to be heated. reflect. Therefore, the reception of the reflected wave from the object to be heated by the antenna as the power feeding unit is greatly reduced, and the reflected wave component returning to the magnetron 16 via the waveguide 21 is suppressed. As a result, in the heating cooker of the first embodiment, the temperature rise in the magnetron 16 due to self-heating is prevented, the life of the magnetron 16 is extended, the power down setting for the magnetron 16 is not required, and the output efficiency It becomes the structure which can aim at improvement.

  In the heating cooker according to the first embodiment, the microwave radiated from the antenna has a strong radiation directivity in a direction perpendicular to the downward surface with the downward surface of the flat plate element 22a as a radiation surface. . Further, the radiation surface of the oblique surface portion As that is bent at the center line of the disk of the flat plate element 22a and set to the bending angle θ occupies 1/2 or more of the entire radiation surface. For this reason, most of the radiated waves from the flat plate element 22a are radiated at an angle θ with respect to the vertical direction. The microwave radiated obliquely with the oblique surface portion As of the flat element 22a as the radiation surface irradiates the object to be heated obliquely, and the direction shifted from the position of the antenna serving as the power feeding portion 22 by the oblique amount. Is reflected. Therefore, in the heating cooker according to the first embodiment, the antenna receives significantly less reflected waves, and the reflected wave components returning to the magnetron 16 can be significantly suppressed. For this reason, the cooking device of Embodiment 1 has a configuration in which the temperature rise in the magnetron 16 due to self-heating is prevented.

  In the heating cooker according to the first embodiment, the waveguide 21 has an L-shape bent at a right angle, and the magnetron 16 is connected to the waveguide 21 in a lateral direction. That is, the magnetron output part 44 of the magnetron 16 is attached so that the lead-out portion of the magnetron 16 is orthogonal to the vertical wall surface of the waveguide 21. For this reason, the vertical dimension (height), which is the vertical direction, of the arrangement space of the waveguide 21 to which the magnetron 16 is bonded becomes small. For example, as compared with the height in the arrangement space of the waveguide 104 in which the magnetron 103 is joined in the vertical direction as in the conventional configuration shown in FIG. 10, the guide in which the magnetron 16 in the first embodiment is joined is used. The height in the arrangement space of the wave tube 21 is small. In addition, since the magnetron 16 is joined to the waveguide 21 in a lateral direction, there is a margin in the space above the magnetron 16 and other components can be arranged.

  Therefore, in the heating cooker according to the first embodiment, it is possible to compactly form a microwave feeding configuration including the magnetron 16, the waveguide 21, the feeding chamber 24, and the like. In addition, in the case of a configuration that is built in the kitchen, an operation panel is provided above the heating chamber, and other configurations such as an electric circuit, a microwave feeding configuration, and a cooling configuration are also integrated above the heating chamber to be compact. It becomes easy to obtain space for mounting.

  In the heating cooker according to the first embodiment, the horizontal portion 42 of the waveguide 21 is connected to the power supply port 25 at the protruding end portion of the power supply chamber 24 projecting upward from the ceiling wall surface of the heating chamber 11, and guided. A vertical portion 43 of the tube 21 extends upward from the bending position C. For this reason, the waveguide 21 is disposed so as to be away from the ceiling wall surface of the heating chamber 11. In the heating cooker according to the first embodiment, the power supply chamber 24 is formed on the ceiling wall surface of the heating chamber 11, and the waveguide 21 is connected to the upper end of the power supply chamber 24. For this reason, the waveguide 21 is coupled to the heating chamber 11 via the power supply chamber 24. Therefore, the contact portion between the waveguide 21 and the power supply chamber 24 can be reduced in area as compared with the case where the waveguide is brought into direct contact with the ceiling wall surface of the heating chamber. The above can be configured not to contact other members. Further, the waveguide 21 is configured to be separated from the heating chamber 11, and a space is formed between them. For this reason, in the structure of the cooking-by-heating machine of Embodiment 1, it is prevented that heat conduction is carried out directly with respect to the waveguide 21 from the ceiling wall surface of the heating chamber 11 in high temperature heating.

  Further, the heating cooker according to the first embodiment is configured such that the amount of heat conducted from the heating chamber 11 to the magnetron 16 through the power supply chamber 24 and the waveguide 21 is significantly reduced. Furthermore, since the magnetron 16 is arranged so as to be separated from the heating chamber 11, in the heating cooker of the first embodiment, heat conduction from the ceiling wall surface of the heating chamber 11 to the magnetron 16 is prevented. Has been.

  In the heating cooker of the first embodiment configured as described above, the magnetron 16 is difficult to receive heat from the ceiling wall surface of the heating chamber 11 during high-temperature heating, and the magnetron passes from the heating chamber 11 through the waveguide 21. The heat transmitted to 16 is reduced, and the temperature rise of the magnetron 16 is prevented. As a result, even in a compact configuration in which the magnetron 16 is provided above the heating chamber 11, the heat transfer from the heating chamber 11 to the magnetron 16 is reduced, the life of the magnetron 16 is extended, and the power-down setting for the magnetron 16 is set. The output efficiency can be improved.

  Furthermore, in the heating cooker according to the first embodiment, the magnetron 16 that is the microwave generation unit is horizontally connected to the vertical transmission path (43) of the waveguide 21 in the horizontal direction. The size in the vertical direction can be made compact.

  In the heating cooker according to the first embodiment, the horizontal transmission distance Lh (see FIG. 2) in the horizontal portion 42 of the waveguide 21 is set to be long, so that the heating chamber 11 and the waveguide 21 are connected to the heating chamber 11. Thus, the amount of heat conducted to the magnetron 16 can be further suppressed. Since the magnetron 16 is generally more efficient at a lower temperature, the output efficiency of the magnetron 16 is improved in the heating cooker of the first embodiment.

  In the heating cooker according to the first embodiment, even if the food 15 is placed on a material having a radio wave shielding function such as a metal tray and the radio wave and other heating functions are used at the same time, power is supplied to the ceiling wall portion. Since microwaves can be supplied downward from the chamber 24, the food 15 can be reliably heated by microwaves without being blocked.

  In addition, since the microwave is radiated obliquely with respect to the vertical direction from the radiation surface of the oblique surface portion As of the flat plate element 22a, the reflected wave component returning to the magnetron 16 that is the microwave generation unit is greatly suppressed. Temperature rise due to self-heating in the magnetron 16 can be prevented.

  Furthermore, since both the waveguide 21 and the magnetron 16 are configured to be separated from the ceiling wall surface of the heating chamber 11, the amount of heat transferred from the heating chamber 11 during high-temperature heating to the magnetron 16 via the waveguide 21 is greatly increased. Thus, the temperature rise of the magnetron 16 is further prevented.

  In the heating cooker according to the first embodiment, since the inclination angle θrad is larger than Ly / 2 / H (Ly / 2 / H <θrad), it is inclined obliquely from the vertical direction from the radiation surface of the oblique surface portion As of the flat plate element 22a. Even if the microwave radiated with strong radiation directivity is reflected near the bottom of the heating chamber 11 by the food 15 or the wall surface, the angle is set so as not to return to the antenna. Further, since the inclination angle θrad of the radiation surface of the oblique surface portion As is smaller than Ly / H (θrad <Ly / H), the inclination angle of the radiation surface is too large and the vertical heating chamber 11 directly below the antenna It is prevented that microwaves cannot be emitted near the bottom center. In the heating cooker according to the first embodiment, in order to reliably prevent the central portion of the food 15 from being heated in a donut shape (ring shape) without being sufficiently heated, The radiation surface is set to a suitable radiation angle. Thereby, in the heating cooker according to the first embodiment, the microwave heating without unevenness of heating is realized, and the reflected wave component returning to the magnetron 16 is greatly suppressed, and the temperature rise due to self-heating in the magnetron 16 is prevented. Can be compatible. For this reason, the cooking device of Embodiment 1 can extend the life of the magnetron 16, eliminate the need for a power-down setting for the magnetron 16, and improve output efficiency.

  In the heating cooker according to the first embodiment, the flat plate element 22a adapted to the wavelength of the microwave for microwave oven of 2450 MHz is realized, and the flat plate element 22a is a substantially circular flat plate having a diameter of about 62 mm. For this reason, the heating cooker according to the first embodiment can resonate at a microwave wavelength of 2450 MHz, and has a unidirectional radiation pattern having a central axis of the beam in a direction perpendicular to the radiation surface of the plate element 22a. Occur. In the cooking device of the first embodiment, the radiated wave from the radiation surface of the oblique surface portion AS of the flat plate element 22a is radiated obliquely by an angle θ with respect to the vertical direction. For this reason, reflection by a diagonal amount (θ) in a direction deviated from the antenna and reception of the reflected wave by the antenna are suppressed, and a temperature rise due to self-heating in the magnetron 16 is prevented. Therefore, the life of the magnetron 16 can be extended, the power down setting of the magnetron 16 is not required, and the output efficiency can be improved.

  In the heating cooker according to the first embodiment, a ventilation region 21 a having a large number of through holes 36 a and 36 b is formed on the E surface, which is the opposite wall surface on both sides of the waveguide 21. In FIG. 2, only the ventilation region 21 a composed of a plurality of through holes 36 a on one wall surface is shown. A ventilation region 21a composed of the through hole 36b is formed. The ventilation region 21 a is a wall surface region in which a plurality of small through holes 36 a and 36 b having a diameter of about 2 to 5 mm are arranged so that the microwave does not leak to the outside of the waveguide 21. Thus, by providing the ventilation region 21a having the plurality of through holes 36a and 36b on the wall surface of the waveguide 21, the heat transfer resistance on the wall surface of the waveguide 21 is increased, and the through hole 36a in the ventilation region 21a is increased. , 36b to allow air movement. As a result, air movement occurs in the waveguide 21, thereby generating a cooling action and reducing heat transferred from the heating chamber 11 to the magnetron 16 through the waveguide 21. Therefore, even in a compact configuration in which the magnetron 16 is provided above the heating chamber 11, the heat transfer from the heating chamber 11 to the magnetron 16 during high-temperature heating is reduced to prevent the temperature of the magnetron 16 from rising, and the magnetron 16 has a long life. Can be achieved. In addition, since the magnetron 16 is generally more efficient at a low temperature, the heating cooker of the first embodiment is configured to improve the microwave heating efficiency by the magnetron 16.

  In the configuration of the first embodiment, since the horizontal transmission distance Lh of the horizontal portion 42 of the waveguide 21 is set to be longer than a half wavelength (λg / 2), the coupling state between the magnetron 16 and the power feeding portion 22 is set. Can be stabilized, and even when the operation state such as a load change fluctuates, a high efficiency can be maintained.

  Further, the heat transfer from the heating chamber 11 to the magnetron 16 is suppressed by the waveguide 21 having a long horizontal transmission path, and the temperature rise of the magnetron 16 is prevented even in a compact configuration in which the magnetron 16 is provided above the heating chamber 11. can do.

  Furthermore, in the heating cooker of the first embodiment, by setting the vertical transmission distance Lv from the center of the magnetron output portion 44 in the waveguide 21 to the bending position C to be shorter than a quarter wavelength (λg / 4). , Transmission efficiency can be improved. In the waveguide 21, by setting the vertical transmission distance Lv to ¼ wavelength or less of the oscillation frequency, the electric field does not reverse in the region from the magnetron output portion 44 to the bent portion including the bent position C. The occurrence of complicated reflections in the transmission path of the waveguide 21 can be prevented. As a result, in the heating cooker of Embodiment 1, it becomes a high oscillation efficiency and becomes an apparatus with high heating efficiency.

  In addition, in the heating cooker of Embodiment 1, it has the dielectric heating part by a microwave as one heating means, and the high temperature heating part by radiation by the upper heater 12 and the lower heater 13 is used together as another heating means. However, the present invention is not limited to such a configuration, and a convection heating unit that performs heating cooking by circulating hot air in the heating chamber may be provided as another high-temperature heating unit.

  Furthermore, the microwave heating device of the present invention may have a configuration in which both a radiation heating unit and a convection heating unit are provided as a high-temperature heating unit together with a dielectric heating unit using a magnetron. In the microwave heating apparatus of the present invention configured as described above, the amount of heat conducted from the heating chamber to the magnetron through the power supply chamber and the waveguide is greatly reduced in the configuration of the dielectric heating unit. For this reason, in the microwave heating apparatus of the present invention, even if other heating means are used, the temperature rise of the magnetron can be prevented and the life can be extended.

  Moreover, in the heating cooker of Embodiment 1, although the case where the flat plate element 22a was circular was shown, a circle is a kind of ellipse, and even if a flat plate element is elliptical, it is orthogonal to the major axis of the ellipse. A fold line may be formed in the direction to form the horizontal plane portion Ah and the oblique surface portion As. If the overall length (Ly) in the major axis direction on the oblique plane of the flat plate element configured in this way is approximately ½ wavelength, the overall length in the major axis direction on the horizontal plane of the flat plate element is skewed. Even if it is slightly different from the length (Ly) in the major axis direction on the surface, it is excited in a resonance mode similar to that of the flat plate element 22a in the heating cooker of Embodiment 1, and its resonance frequency only slightly changes. Therefore, if the overall length of the long axis direction in the horizontal plane of the flat plate element is in the range of about 1/4 wavelength to 3/4 wavelength, a flat plate element that sufficiently realizes the characteristics of exhibiting the function of the present invention is configured. be able to.

  Note that the shape of the flat plate element described here is only in the case of a circle and an ellipse, but the flat plate element may be rectangular in order to be in a resonance state, and does not have to be a perfect rectangle or ellipse. For example, it is needless to say that various shapes such as a rectangle with a large cut or rounded corner, and an intermediate shape thereof are conceivable. That is, the flat plate element may basically be a flat plate having a maximum width on the oblique plane of about ½ wavelength and a maximum width on the horizontal plane in the range of about ¼ wavelength to ¾ wavelength.

(Embodiment 2)
Hereinafter, the heating cooker of Embodiment 2 is demonstrated as an example of the microwave heating device of this invention. The heating cooker according to the second embodiment is greatly different from the heating cooker according to the first embodiment described above in the configuration for supplying microwaves to the heating chamber.

  In the following description of the heating cooker of the second embodiment, the same reference numerals are given to those having the same functions and configurations as the components in the heating cooker of the first embodiment, and the detailed description thereof will be given in the embodiment. The explanation of 1 applies. FIG. 4 is a front sectional view showing the internal configuration of the main part of the heating cooker according to the second embodiment. FIG. 5 is a side cross-sectional view of the heating cooker shown in FIG. 4.

  As shown in FIGS. 4 and 5, in the heating cooker of the second embodiment, the waveguide 21 that transmits the microwave from the magnetron 16 has a horizontal portion as in the waveguide 21 of the first embodiment. 42 and a vertical portion 43, and is bent into an L shape. That is, the internal passage of the waveguide 21 is constituted by a horizontal transmission path and a vertical transmission path bent at a right angle. The magnetron 16 is connected laterally (horizontal connection) so that the magnetron output portion 44 is inserted in the horizontal direction with respect to the waveguide 21. That is, the lead-out portion of the magnetron output portion 44 is provided so as to be orthogonal to the vertical side surface of the vertical portion 43 of the waveguide 21. Therefore, in the state where the magnetron 16 is connected to the waveguide 21, the vertical dimension, which is the vertical direction, is small as in the configuration of the first embodiment.

  As described above, the feeding portion 22 that is an antenna having the flat plate element 22a and the vertical axis element 22b is connected to the horizontal portion 42 of the waveguide 21 having the L-shaped internal passage (transmission path). . A power supply chamber 49 that houses the flat plate element 22a is formed at a substantially central portion of the ceiling wall surface of the heating chamber 11. The power supply chamber 49 has a shape in which a lower end portion extends in a circular shape, and has a truncated cone shape. The power supply chamber 49 is formed by drawing the ceiling wall surface of the heating chamber 11. In the second embodiment, since a cover that covers the lower end portion of the power supply chamber 49 is not provided, there is no dielectric loss that occurs slightly in the cover, and the heating efficiency is further improved.

  FIG. 6 is a perspective view showing the waveguide 21 and the power feeding chamber 49 in the heating cooker according to the second embodiment. As shown in FIG. 6, in the waveguide 21 of the second embodiment, the horizontal transmission distance Lh of the horizontal portion 42 is about 135 mm, as in the waveguide 21 of the first embodiment, and the half wavelength (λg / 2) is set longer (Lh> λg / 2). The vertical transmission distance Lv (see FIG. 2) of the vertical portion 43 of the waveguide 21 is about 15 mm, and is set shorter than a quarter wavelength (λg / 4) (Lv <λg / 4). In the second embodiment, the width a of the internal passage that is the transmission path of the waveguide 21 is 80 mm as in the first embodiment. Accordingly, since the oscillation frequency of the magnetron 16 is about 2450 MHz, the in-tube wavelength λg in the waveguide 21 whose internal passage width a is about 80 mm is about 190 mm, and the half wavelength (λg / 2) Is 95 mm (λg / 2 = 95 mm).

  As shown in FIG. 4, the bottom portion of the power supply chamber 49 protrudes into the heating chamber 11 and serves as a shielding wall protruding downward from the ceiling wall surface of the heating chamber. On the other hand, the upper end portion of the power supply chamber 49 protrudes upward from the ceiling wall surface of the heating chamber 11. The power supply port 25 formed in the horizontal portion 42 of the waveguide 21 is connected to an opening formed in the upper end portion of the power supply chamber 49 and functions integrally as a coupling hole. For this reason, the waveguide 21 is connected to the heating chamber 11 via the power supply chamber 49. Therefore, the contact portion between the waveguide 21 and the power supply chamber 49 can be reduced in area as compared with the case where the waveguide is brought into direct contact with the ceiling wall surface of the heating chamber. The above can be configured not to contact other members. The waveguide 21 is configured to be separated from the heating chamber 11, and a space is formed between them. For this reason, direct heat conduction from the ceiling wall surface of the heating chamber 11 during high-temperature heating to the waveguide 21 is prevented. In addition, on the upper surface of the ceiling wall surface of the heating chamber 11, a heat insulating portion 50 formed of a heat insulating material is provided so as to surround the power supply chamber 49. Thus, since the heat insulation part 50 is provided, the discharge | release heat | fever upward from the ceiling wall surface of the heating chamber 11 is suppressed. The heat insulating portion 50 is disposed in a space between the waveguide 21 and the ceiling wall surface of the heating chamber 11, so that the waveguide 21 is not directly heated by the heat released from the ceiling wall surface of the heating chamber 11. It is configured. Therefore, the amount of heat conducted from the heating chamber 11 during high temperature heating to the magnetron 16 via the waveguide 21 is greatly suppressed. Furthermore, since the magnetron 16 is also configured to be separated from the heating chamber 11, direct heat conduction from the ceiling wall surface of the heating chamber 11 is prevented.

  As shown in FIGS. 4 and 5, a disc having a diameter of 62 mm is placed in the power supply chamber 49 at a predetermined angle θ (eg, 10 A flat plate element 22a having a shape bent at (°) is provided. The flat element 22a is set to resonate at the wavelength of the microwave used and to generate a unidirectional radiation pattern having a central axis of the beam in a direction perpendicular to the radiation surface of the flat element 22a. For this reason, the microwave is radiated downward from the radiation surface of the flat plate element 22a of the power feeding unit 22 provided in the coupling hole portion of the ceiling wall surface of the heating chamber 11, and a part of the microwave is perpendicular to the vertical direction. Radiated with a predetermined angle θ. A part of the radiated microwave is reflected at the boundary surface with the food 15 that is the object to be heated. . Therefore, the reception of the reflected wave by the antenna is greatly reduced, and the reflected wave component returning to the magnetron 16 via the antenna can be suppressed. As a result, in the heating cooker according to the second embodiment, the temperature rise in the magnetron 16 due to self-heating is prevented together with the temperature rise due to heat transfer from the heating chamber 11 described above.

  Therefore, in the heating cooker of the second embodiment, even if the magnetron 16 is provided in a compact configuration above the heating chamber 11, the life of the magnetron 16 is extended, the power-down setting of the magnetron 16 is unnecessary, and the output efficiency Can be improved.

  Further, by setting the horizontal transmission distance Lh of the horizontal portion 42 of the waveguide 21 to be longer than a half wavelength (λg / 2), the coupling state between the magnetron 16 and the power feeding unit 22 is stabilized, and the operation state such as a load change is achieved. Even if it fluctuates, it becomes the composition which can maintain high heating efficiency. The heat transfer from the heating chamber 11 to the magnetron 16 is suppressed by the waveguide 21 having a long horizontal transmission path, and the temperature of the magnetron 16 can be increased even in a compact configuration in which the magnetron 16 is provided above the heating chamber 11. It becomes the structure which can be prevented.

  Furthermore, in the heating cooker of the second embodiment, by setting the vertical transmission distance Lv from the center of the magnetron output portion 44 in the waveguide 21 to the bending position C to be shorter than ¼ wavelength (λg / 4). The oscillation efficiency can be improved. In the waveguide 21, by setting the vertical transmission distance Lv to ¼ wavelength or less of the oscillation frequency, the electric field does not reverse in the region from the magnetron output portion 44 to the bent portion including the bent position C. The occurrence of complicated reflections in the transmission path of the waveguide 21 can be prevented. As a result, in the cooking device of the second embodiment, the oscillation efficiency is greatly improved.

  As described above, in the heating cooker according to the second embodiment, the waveguide 21 has an L-shaped bent shape, and the power supply chamber 49 projects upward from the ceiling wall surface of the heating chamber 11. For this reason, the heat insulation part 50 can be provided in the space between the horizontal part 42 of the waveguide 21 and the ceiling wall surface of the heating chamber 11. In this manner, the heating chamber 11 and the waveguide 21 are coupled via the power supply chamber 49, and the heat insulating portion 50 that prevents heat conduction is provided in the space between the heating chamber 11 and the waveguide 21. Thus, it becomes possible to construct a cooking device having high heating efficiency with a compact configuration.

  Moreover, in the heating cooker of Embodiment 2, the ceiling wall surface of the heating chamber 11 is provided by providing the waveguide 21 bent upward at the upper end portion of the power supply chamber 49 protruding from the ceiling wall surface of the heating chamber 11. It is possible to secure a space for providing the heat insulating portion 50 on the wall, and to lay the heat insulating portion 50 thick. In addition, the heating cooker of Embodiment 2 is provided with a ventilation fan 61 that exhausts the heating chamber and a lamp 62 that serves as illumination in the heating chamber.

  In the cooking device according to the second embodiment configured as described above, in the cooking process using a heating unit such as a heater as the high temperature heating unit, the heat insulating unit 50 releases the heat upward from the heating chamber 11. The heat is shut off. For this reason, the heating cooker of Embodiment 2 is the structure which can aim at the significant improvement of heating efficiency.

  Furthermore, the cooking device of the second embodiment has a configuration that significantly suppresses the amount of heat conducted from the heating chamber 11 to the magnetron 16 in the case of cooking in which dielectric heating is coupled with radiation heating and convection heating by a heater. ing. For this reason, the cooking device of Embodiment 2 becomes a cooking device which is compact and has high heating efficiency.

  In the configuration of the heating cooker according to the second embodiment, as shown in FIGS. 4 and 5, an upper heater 12 is provided on the upper side in the heating chamber 11, and is below the bottom wall of the heating chamber 11. A lower heater 13 is provided on the side. Moreover, in the heating cooker of Embodiment 2, the bottom wall of the heating chamber 11 is heated by the lower heater 13. Furthermore, the heating cooker according to the second embodiment has a back heater 30 and a circulation fan 31 for circulating hot air for oven cooking on the back side of the heating chamber 11 (see FIG. 5). Thus, the heating cooker of Embodiment 2 is the structure which can heat a foodstuff directly by radiant heat and convection heat besides the heating by dielectric heating. Therefore, the heating cooker according to the second embodiment is a cooker having a high function capable of supporting a plurality of cooking menus.

  One end (terminal side) of the upper heater 12 provided in the upper part of the heating chamber 11 is fixed on the back surface of the heating chamber 11, and the front surface side of the upper heater 12 is held by the upper heater support 51 (FIG. 5). reference). The upper heater support 51 is configured to hold the upper heater 12 with a degree of freedom so as to cope with the thermal expansion of the upper heater 12. The material of the upper heater support 51 is made of a ceramic such as an insulator according to the required heat resistance temperature, and a material that has a smaller influence on the microwave than the metal fitting is used.

  As shown in FIGS. 4 and 5, the lower end portion of the power supply chamber 49 protrudes from the ceiling wall surface inside the heating chamber 11, and the upper heater 12 is disposed around the lower end portion of the power supply chamber 49. That is, the upper heater 12 is provided to avoid a position directly below the opening at the lower end portion of the power supply chamber 49. Thus, since the upper heater 12 is provided outside the shielding wall, which is the lower end portion of the power supply chamber 49 projecting from the heating chamber, it is not directly heated by the microwave from the power supply unit 22. The loss of microwave heating is prevented.

  FIG. 7 is a layout diagram showing the lower surface side of the ceiling wall surface of the heating chamber 11, and shows the power feeding unit 22, the power feeding chamber 49, the upper heater support 51, the upper heater 12 and the like provided on the ceiling wall surface. In FIG. 7, the upper side is the front side of the apparatus. As shown in FIG. 7, the upper heater 12 is disposed so as to avoid the opening at the lower end portion of the power supply chamber 49, and is held movably by the upper heater support 51 at a plurality of locations.

  In the heating cooker according to the second embodiment, the lower heater 13 provided below the bottom wall of the heating chamber 11 is configured to heat the bottom wall of the heating chamber 11. The bottom wall of the heating chamber 11 is heated by the lower heater 13 to generate radiant heat and convection heat inside the heating chamber 11.

  In the configuration of the heating cooker according to the second embodiment, the back heater 30 for circulating hot air and the circulation fan 31 for cooking the oven are provided on the back side of the heating chamber 11, and a convection heating unit is configured. ing. The convection heating unit is configured to heat the air inside the heating chamber 11 by the heat generated by the back heater 30 and the rotation of the circulation fan 31 so that the hot air circulates inside the heating chamber 11. The heating cooker according to the second embodiment is configured so that hot air circulates inside the heating chamber 11 and heats the food 15 that is the object to be heated by the convection heating unit configured as described above.

  Furthermore, in the heating cooker according to the second embodiment, as shown in FIG. 5, a door 32 for opening and closing is provided on the front side, and opening and closing of the object to be heated with respect to the heating chamber 11 by opening and closing the door 32. Is configured to do. On the upper portion of the door 32, an operation unit 33 is provided for setting various conditions for cooking.

  As shown in FIG. 5, in the cooking device of the second embodiment, a gap 34 is formed between the door 32 and the operation unit 33. The gap 34 constitutes a cooling passage for discharging cooling air from the cooling fan 35 provided at a rear position in the upper space of the heating chamber 11. Cooling air from the cooling fan 35 flows in contact with the upper surface of the heat insulating portion 50 and passes through the small through holes 36a and 36b formed on opposite wall surfaces of the waveguide 21 and exhausts forward from the gap 34. Has been. Here, the small through holes 36a and 36b are holes having a size that does not allow microwaves to leak, for example, a diameter of 2 to 5 mm. The ventilation region 21c having the through holes 36a and 36b (see FIG. 5) is provided in the vicinity of the feeding port 25 of the waveguide 21, but the E surface of the vertical portion 43 of the waveguide 21 as shown in FIG. In addition, another ventilation region 21a having a large number of through holes 36a and 36b is formed in the same manner as in the configuration of the first embodiment. Therefore, the cooling air from the cooling fan 35 cools the heat insulating portion 50 and flows through the waveguide 21 to cool the waveguide 21.

  As described above, in the heating cooker according to the second embodiment, by providing the cooling fan 35 and the cooling passage, the cooling fan 35 is driven and heated even when the heating chamber becomes hot due to, for example, oven cooking. The ceiling wall surface of the chamber 11 can be cooled from the outside. For this reason, the heating cooker of Embodiment 2 can prevent the temperature rise of the various components which comprise the control part 20 grade | etc., Arrange | positioned above the ceiling wall surface of the heating chamber 11. FIG. In addition, the heating cooker according to the second embodiment has a configuration in which a temperature rise is unlikely to occur even when component mounting arranged on the upper side of the ceiling wall surface of the heating chamber 11 is performed at a high density. For this reason, it becomes possible for the heating cooker of Embodiment 2 to be set as a compact structure as the whole apparatus.

  Further, in the heating cooker of the second embodiment, the cooling fan 35 can forcibly flow the cooling air through the cooling passage communicating with the through holes 36 a and 36 b of the waveguide 21. For this reason, the heating cooker of Embodiment 2 has improved the cooling effect of the magnetron 16 and the waveguide 21, and the temperature rise of the magnetron 16 is achieved even in a compact configuration in which the magnetron 16 is provided above the heating chamber 11. Therefore, the life of the magnetron 16 can be extended, the power-down setting for the magnetron 16 is not required, and the output efficiency can be improved. In addition, since the magnetron is generally more efficient at lower temperatures, the microwave heating efficiency by the magnetron 16 is improved in the configuration of the heating cooker of the second embodiment.

  In the heating cooker according to the second embodiment, the lower end portion of the power supply chamber 49 is configured to protrude into the heating chamber 11, and the upper heater 12 is disposed on the outer periphery of the lower end portion of the power supply chamber 49. Since the upper heater 12 is arranged in this way, the microwave radiated from the power supply unit 22 is directly radiated to the food 15 and is not blocked by the upper heater 12. Thus, in the configuration of the second embodiment, since the upper heater 12 does not block the microwave from the power feeding unit 22, the microwave from the power feeding unit 22 heats the upper heater 12 and is lost. Thus, the heating efficiency is improved.

  In the heating cooker according to the second embodiment, the protruding portion of the power supply chamber 49 into the heating chamber 11 functions as a microwave shielding wall. This shielding wall is comprised with the material which shields the microwave radiated | emitted from the flat element 22a. For this reason, the microwave radiated in the substantially horizontal direction from the power feeding unit 22 that is a rotating antenna is reliably blocked by the shielding wall, and the upper heater 12 and the upper heater support 51 provided around the power feeding chamber 49 are connected to the power feeding unit. No direct heating by microwaves from 22. That is, the shielding wall reflects microwaves from the antenna portion so that the high-temperature heating portion of the upper heater 12 disposed in the outer peripheral portion of the power supply chamber 49 is not directly heated. As a result, the cooking device of the second embodiment has a configuration in which the loss of microwaves is greatly suppressed, and the food that is the object to be heated can be cooked with high heating efficiency.

(Embodiment 3)
Hereinafter, the heating cooker of Embodiment 3 is demonstrated as an example of the microwave heating device of this invention. The heating cooker according to the third embodiment is greatly different from the heating cookers according to the first and second embodiments described above in the configuration for supplying microwaves to the heating chamber. In the cooking device of the third embodiment, the configuration of the first embodiment or the second embodiment is applied to other configurations.

  In the description of the heating cooker according to the third embodiment below, components having the same functions and configurations as the components in the heating cooker according to the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The description of Embodiment 1 and Embodiment 2 is applied to the description.

8 and 9 are main part cross-sectional views showing a power feeding unit and an object to be heated in the heating cooker according to the third embodiment.
As shown in FIG. 8, the plate element 22a of the power feeding unit 22 that stirs and radiates the microwave transmitted from the waveguide 21 is made of metal, has a thickness of 1 mm, and has a disk shape with a diameter of 62 mm. Have. The vertical axis element 22b that transmits the rotation of the motor 23 to the flat plate element 22a is connected to a position that is eccentric about 12 mm from the center of the disk in the flat plate element 22a, and the flat plate element 22a has a predetermined angle θ (θ = 10 °) is obliquely connected to the vertical axis element 22b so as to face downward. As described above, the entire radiation surface of the flat plate element 22a shown in FIG. 8 in the third embodiment is provided obliquely by a predetermined angle θ (θ = 10 °) with respect to the horizontal plane. In the flat element 22a shown in FIG. 8, a direction facing downward from the horizontal direction by a predetermined angle θ = 10 ° is defined as a Y direction, and a direction corresponding to the Y direction on a horizontal plane is defined as an X direction. That is, the angle θ between the X direction and the Y direction is 10 °. If the length of the entire radiation surface in the Y direction of the flat element 22a, which is a disc having a diameter of 62 mm, is Ly, Ly is 62 mm.

  If the height from the position of the radiation surface of the flat plate element 22a facing the position where the vertical axis element 22b is connected to the surface of the food 15 is H in the heating chamber 11 shown in FIG. In the cooking device, H is about 330 mm. Therefore, since the inclination angle θrad of the flat plate element 22a is about 0.175, it is set to an angle larger than Ly / 2 / H≈0.094 and smaller than Ly / H≈0.188 (Ly / 2). / H <θrad <Ly / H).

  In the vertical axis element 22b, the portion on the motor 23 side is made of fluororesin, and the portion on the flat plate element 22a side is made of metal. The metal portion in the vertical axis element 22b includes a portion that enters the inside of the waveguide 21 and a portion that protrudes toward the feeding chamber 24 through the feeding port 25 of the waveguide 21. In addition, the gap between the metal portion and the power supply port 25 in the vertical axis element 22b is ensured by a distance of 5 mm or more.

  In the heating cooker shown in FIG. 8 configured as described above, the flat plate element 22a is arranged so that the microwave is radiated downward at a predetermined angle θ. A part of the light is reflected at the boundary surface with the food 15 that is the object to be heated. Therefore, the reception of the reflected wave from the object to be heated by the antenna serving as the power feeding unit is greatly reduced, and the reflected wave component returning to the magnetron 16 via the waveguide 21 is suppressed. As a result, in the configuration of the heating cooker shown in FIG. 8, the temperature rise in the magnetron 16 due to self-heating is prevented, the life of the magnetron 16 is extended, the power-down setting of the magnetron 16 is unnecessary, and the output efficiency is improved. Can be achieved.

  FIG. 9 shows still another configuration of the heating cooker according to the third embodiment. In the configuration of the heating cooker illustrated in FIG. 9, the bending line in the flat plate element 22 a of the power feeding unit 22 is configured by a curved surface.

  In the configuration of the heating cooker shown in FIG. 9, the flat plate element 22a of the power feeding unit 22 that stirs and radiates the microwave transmitted from the waveguide 21 is made of metal, has a thickness of 1 mm, and a diameter of 62 mm. It is a disk. The flat plate element 22a has a shape in which the center line of the disk is symmetrical and bent at the center line portion by a curved surface. That is, the flat element 22a shown in FIG. 9 is divided into two regions at the center line portion of the disk, and the two regions are connected by a curved surface.

  In the configuration of the heating cooker shown in FIG. 9, the vertical axis element 22b that transmits the rotation of the motor 23 to the flat plate element 22a is connected to a position that is eccentric about 12 mm from the center of the disk in the flat plate element 22a. Accordingly, one region of the flat plate element 22a is connected to the vertical axis element 22b and arranged in the horizontal direction. The other area of the flat plate element 22a is connected to one area connected to the vertical axis element 22b by a curved surface, and is directed downward by a predetermined angle θ (θ = 10 °) with respect to the one curved surface. Are arranged as follows. In the flat element 22a shown in FIG. 9, the diameter direction corresponding to the ridgeline of the curved surface is the horizontal direction, and the direction perpendicular to the horizontal direction of the ridgeline of the curved surface and facing downward is defined as the Y direction. Therefore, a substantially half region of the flat plate element 22a is arranged to be in the Y direction facing downward by a predetermined angle θ = 10 ° with respect to the horizontal direction. In the flat element 22a which is a disc having a diameter of 62 mm, when the length of all radiation surfaces in the Y direction is Ly, the angle θ is small, so the length Ly in the Y direction may be considered to be about 62 mm.

  Accordingly, even in the shape shown in FIG. 9, since the inclination angle θrad of the flat plate element 22a is about 0.175, it is set to an angle larger than Ly / 2 / H≈0.094 and smaller than Ly / H≈0.188. (Ly / 2 / H <θrad <Ly / H).

  Also in the vertical axis element 22b shown in FIG. 9, the motor 23 side portion is made of fluororesin, and the flat plate element 22a side portion is made of metal. The metal portion in the vertical axis element 22b includes a portion that enters the inside of the waveguide 21 and a portion that protrudes toward the feeding chamber 24 through the feeding port 25 of the waveguide 21. In addition, the gap between the metal portion and the power supply port 25 in the vertical axis element 22b is ensured by a distance of 5 mm or more.

  In the heating cooker shown in FIG. 9 configured as described above, the flat plate element 22a is arranged so that the microwave is radiated downward at a predetermined angle θ. A part of the light is reflected at the boundary surface with the food 15 that is the object to be heated, but this reflected wave is reflected in a direction shifted from the antenna by an angle θ with respect to the vertical direction. Therefore, the reception of the reflected wave from the object to be heated by the antenna as the power feeding unit is greatly reduced, and the reflected wave component returning to the magnetron 16 via the waveguide 21 is suppressed. As a result, in the configuration of the heating cooker shown in FIG. 9, the temperature rise in the magnetron 16 due to self-heating is prevented, the life of the magnetron 16 is extended, the power-down setting of the magnetron 16 is unnecessary, and the output efficiency is improved. Can be achieved.

  As described above, in the heating cooker according to the third embodiment, since the power feeding unit 22 is provided with the flat plate element 22a that radiates the microwave at a predetermined angle θ downward, by receiving the reflected wave with the antenna, The reflected wave component returning to the magnetron 16 can be greatly suppressed. As a result, the heating cooker according to the third embodiment prevents the temperature rise in the magnetron 16 due to self-heating, and exhibits substantially the same characteristics and functions as the configuration of the first embodiment described above. The life can be extended, the power down setting for the magnetron 16 is not required, and the output efficiency can be greatly improved.

  As described above, as described in the above embodiments, in the microwave heating apparatus of the present invention, microwaves are radiated downward at a predetermined angle θ from the coupling hole portion of the ceiling wall surface of the heating chamber. Since the flat plate element is arranged as described above, the reflected wave of the radiated microwave at the boundary surface with the object to be heated is reflected in a direction shifted from the antenna by an angle θ with respect to the vertical direction. Therefore, receiving the reflected wave again by the antenna is reduced, and the reflected wave component returning to the microwave generation unit can be greatly suppressed. As a result, the microwave heating device of the present invention can prevent a temperature rise in the microwave generation unit due to self-heating. Further, the microwave heating device of the present invention can extend the life of the microwave generator even if the microwave generator has a compact configuration provided above the heating chamber. Power-down setting is unnecessary, and the output efficiency can be greatly improved.

  The present invention is not limited to a heating cooker that radiates microwaves to food and heats it in a dielectric manner, particularly a heating cooker that is used in combination with other heating such as an oven, grill, and superheated steam, as well as a drying device, a heating device for ceramics, It is useful in a microwave heating apparatus in various industrial applications such as a garbage disposal machine or a semiconductor manufacturing apparatus.

DESCRIPTION OF SYMBOLS 11 Heating chamber 12 Upper heater 13 Lower heater 15 Food 16 Magnetron 21 Waveguide 22 Feeding part 22a Flat plate element 22b Vertical axis element 24 Feeding room 25 Feeding port 42 Horizontal part 43 Vertical part 49 Feeding room

Claims (5)

A heating chamber for storing an object to be heated and performing high-frequency heating by irradiating the object to be heated with microwaves,
A microwave power feeding chamber formed to protrude upward from the ceiling wall surface of the heating chamber,
A microwave generating unit for generating microwaves for high-frequency heating the object to be heated in the heating chamber;
A waveguide that connects the power supply chamber and the microwave generator to transmit microwaves, and a coupling hole formed in a joint portion between the power supply chamber and the waveguide is provided in a vertical direction. A feeding unit having a vertical axis element formed and a flat element having a radiation surface that is joined to the vertical axis element and emits microwaves to the heating chamber;
At least a part of the radiation surface of the microwave radiation surface of the flat plate element is disposed at an angle with respect to the horizontal direction at a predetermined angle θ ,
The area of the radiation surface having the predetermined angle θ is configured to be 1/2 or more of the entire radiation surface in the flat plate element,
In the entire radiation surface of the flat element, the total length in the inclination direction of the radiation surface inclined by a predetermined angle θ with respect to the horizontal plane is Ly, and corresponds to the position where the object to be heated in the heating chamber is joined to the vertical axis element. When the height to the position of the radiation surface of the flat plate element is H,
An inclination angle θrad of the inclined radiation surface is set to an angle larger than Ly / 2 / H and smaller than Ly / H, and configured to reduce receiving of a reflected wave from the object to be heated by the power feeding unit. microwave heating apparatus. In the heating chamber, a high-temperature heating unit that heats an object to be heated with high-frequency heating and at least one of radiant heat or convection heat,
In the configuration in which the microwave generation unit and the waveguide are disposed above the heating chamber,
The waveguide has a horizontal line and a vertical part and has a transmission line bent at a right angle, the microwave generating part is horizontally connected to the vertical part, and the heating chamber is connected to the horizontal part. 2. The power supply chamber provided on the ceiling wall surface is connected via a coupling hole, and both the waveguide and the microwave generation unit are disposed apart from the heating chamber. Microwave heating device. The plate element is a microwave heating apparatus according to claim 1 or claim 2 in diameter are composed of a substantially circular flat plate of substantially 62 mm. The microwave heating device according to claim 3 , wherein the power feeding unit is configured such that the vertical axis element is joined to a position eccentric from a center of the disk of the flat element, and the vertical axis element rotates. The flat plate element, a microwave according to claim 3 or claim 4 and formed by bending at a predetermined angle θ to one of the radiating surfaces to the other radiating surface on a straight line fold line containing the center line of the disc Heating device.

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