JP2001235157A - High frequency heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save space, protect a heating conductor and improve unevenness of heating, in a high frequency heating device for performing cooking by microwaves, radiant heat or the like. SOLUTION: The high frequency heating device comprises a heating conductor 4, magnetron 3 and a waveguide 6, all of which are put together on the ceiling or the floor of a heating chamber 1. The heating conductor 4 is shielded from microwaves by a shielding member 7, while the shielding member 7 is also used as an antenna for emitting the microwaves with the fixture of a microwave connecting portion 8 to the shielding member 7. In this way, when the heating conductor 4 is used, a heating object 2 can be irradiated with the radiant heat from the heating conductor 4. Also, when the magnetron 3 is used, the heating conductor 4 can be prevented from being abnormally heated by the microwaves emitted from the magnetron 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus for heating and cooking a heating object accommodated in a heating chamber by microwaves or radiant heat. Examples of the high-frequency heating device include a microwave oven.

[0002]

2. Description of the Related Art As a conventional microwave oven, there is a microwave oven capable of performing heating cooking using microwaves emitted from a magnetron and heating cooking using radiation heat emitted from a heater or the like.

In general, a heater is often installed on either the ceiling or the floor of a heating chamber, and a magnetron and a waveguide are installed on a side wall of the heating chamber.

[0004]

However, in the above-described conventional example, it can be said that there is much waste in space due to the relation that the heater and the magnetron are installed at separate places.
It has been difficult to reduce the size of the device.

Therefore, the applicant of the present application has considered to reduce the outer shape of the apparatus by installing a magnetron and a waveguide near the place where the heater is installed.

In this method, if a heater whose heating conductor is not covered with a metal tube or the like is used, microwaves emitted from the magnetron will be absorbed by the heating conductor. For this reason, the heating conductor may generate abnormal heat, which may adversely affect the temperature control of the cooking, or the microwave may not be applied to the area of the heating object behind the heater, so that the heating object is uniformly heated. It was found that heating was not possible and uneven heating occurred.
There is room for improvement here.

[0007] In view of such circumstances, an object of the present invention is to reduce the space, protect the heat-generating conductor, and improve the uneven heating in a high-frequency heating device that performs cooking by microwave or radiant heat.

[0008]

A first high-frequency heating apparatus according to the present invention heats and cooks an object to be housed in a heating chamber by microwaves or radiant heat, and comprises a magnetron emitting microwaves, and a heating chamber. A heating conductor that is installed on either the ceiling or the floor and emits radiant heat, and a microwave emitted from a magnetron antenna that is attached to the heating chamber near the installation location of the heating conductor and is connected to the heating chamber and transmits the microwave to the heating conductor. A waveguide propagating in the vicinity, a metal shield member configured to shield the heating conductor against microwaves emitted from the magnetron and to emit radiant heat emitted from the heating conductor to the heating chamber side, and attached to the shield member. And a microwave coupling unit that couples with an electromagnetic field of microwaves emitted from the magnetron, and
It is characterized in that the shield member is used as a radiation antenna for emitting microwaves to the heating chamber side by a microwave coupling portion.

The second high-frequency heating apparatus according to the present invention is characterized in that
Wherein the shield member is provided with a metal cylindrical frame in which a heating conductor is housed, a metal net attached to upper and lower openings thereof, and a cylindrical member provided at several positions around the cylindrical frame. And a leg for setting the frame so as to float with respect to the heating chamber, and the microwave coupling portion is attached to a net on the side of the shield member close to the wall of the heating chamber. It is characterized by.

The third high-frequency heating apparatus according to the present invention is characterized in that
In the above configuration, the microwave coupling portion protrudes into the waveguide, and the distance from the lower end of the microwave coupling portion to the outer peripheral surface of the cylindrical frame of the shield member is λ
/ 2 or a length that is an integral multiple of λ / 2.

The fourth high-frequency heating apparatus according to the present invention is characterized in that
In the above configuration, the total length of the legs is λ / 4 or λ such that the legs of the shield member have an infinite impedance in which the shield member serving as the radiation antenna is floated without being grounded to the heating chamber. / 4 + λ / 2, and is set to an integral multiple of / 4 + λ / 2.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on embodiments shown in the drawings.

FIG. 1 and FIG. 2 show an embodiment of the present invention. In this embodiment, a microwave oven is taken as an example of the high-frequency heating device. FIG. 1 is a front view showing the internal configuration of the microwave oven, and FIG. 2 is a perspective view of the shield member in FIG.

As shown in FIG. 1, the microwave oven according to this embodiment has a configuration in which a heating target 2 housed in a heating chamber 1 is heated by microwaves generated from a magnetron 3 or radiant heat generated from a heating conductor 4. ing.

On the floor side of the heating chamber 1, a shelf plate 5 made of a dielectric material such as glass is mounted in a floating state with a required gap. The heating object 2 is placed on this shelf 5
Is placed.

In this embodiment, in order to save the space of the entire microwave oven, a coil-shaped heat-generating conductor 4 is installed on the floor side of the heating chamber 1 and the microwave generated from the magnetron 3 is placed on the floor of the heating chamber 1. Is provided.

A specific description will be given. First, magnetron 3
Is installed via a waveguide 6 attached to the lower surface of the floor of the heating chamber 1. The waveguide 6 is formed of a metal-made bottomed box formed in a horizontally long rectangular parallelepiped, and one end in the longitudinal direction thereof is connected to the heating chamber 1. In the waveguide 6, the other end in the longitudinal direction protrudes toward one side wall of the heating chamber 1, and the magnetron 3 is attached to the ceiling of the protruding portion. The antenna 3a of the magnetron 3 is connected to the waveguide 6
It protrudes into the interior from the ceiling of the protruding part.

The heating conductor 4 is provided with a shield member 7 for shielding microwaves emitted from the magnetron 3.
And is installed in a space between the upper surface of the floor of the heating chamber 1 and the shelf 5 via the shield member 7.

In such a configuration, the heating conductor 4 may be abnormally heated by microwaves. To prevent this, the heating conductor 4 is protected by a metal shield member 7. Also, this shield member 7
Are used as radiation antennas for diffusing and radiating microwaves over a wide area in the heating chamber 1. Further, in order to prevent the microwave from becoming difficult to irradiate the heating target 2 due to the presence of the heating conductor 4, the shield member 7 is formed in the following shape.

The shield member 7 includes a metal cylindrical frame 7a in which the heat generating conductor 4 is accommodated, metal nets 7b and 7c attached to the upper and lower openings thereof, and a plurality of circumferential portions of the cylindrical frame 7a. And legs 7d for mounting the cylindrical frame 7a so as to float with respect to the heating chamber 1. A wire for connecting the heating conductor 4 to a power supply (not shown) is passed through the inside of the leg 7d.

The entire shield member 7 is made of magnetron 3
In order to function as a radiation antenna for radiating microwave energy emitted from the inside of the heating chamber 1, a microwave coupling portion 8 for coupling with a microwave electromagnetic field is attached to the center of the wire mesh 7 c below the shield member 7. ing.

The microwave coupling portion 8 protrudes into the waveguide 6, and the distance L1 from the lower end of the microwave coupling portion 8 to the outer peripheral surface of the cylindrical frame 7a of the shield member 7 is: The length is set to “λ / 2 or an integral multiple of λ / 2”.

Further, since the leg 7d of the shield member 7 serving as the radiation antenna is attached to the floor of the heating chamber 1, the shield member 7 serving as the radiation antenna is connected to the heating chamber 1.
The total length L1 of the leg portion 7d is set to "λ / 4 or an integral multiple of λ / 4 + λ / 2" so that the impedance of the leg portion 7d is infinite and floated without being grounded.

Next, the operation will be described. First, when heating the heating target 2 using the radiant heat from the heating conductor 4, only the heating conductor 4 may be driven. in this case,
Since only the upper wire mesh 7b of the shield member 7 exists above the heat generating conductor 4, when the heat generating conductor 4 is driven, radiant heat is efficiently released from the gap between the upper wire meshes 7b. The object 2 can be efficiently heated.

On the other hand, when heating the heating target 2 using the microwave from the magnetron 3, only the magnetron 3 needs to be driven. In this case, when the microwave emitted from the magnetron antenna 3a propagates through the waveguide 6 and reaches the microwave coupling portion 8 disposed at the connection portion between the waveguide 6 and the heating chamber 1, the microwave is transmitted. The microwave electromagnetic field is coupled to the wave coupling section 8. Accordingly, since the shield member 7 microwave-connected to the microwave coupling portion 8 functions as a radiation antenna, the shield member 7 passes from the outer periphery of the shield member 7 through the shelf 5 made of a dielectric material. As a result, microwave energy 10 is released into the heating chamber 1, and the object 2 to be heated is heated by the microwave. At this time, since the microwave cannot enter the inside of the shield member 7, the heating conductor 4 disposed inside the shield member 7 does not have to be heated by the microwave. As a result, the problem that the heat generating conductor 4 generates abnormal heat unlike the conventional example does not occur.

As described above, in the above embodiment,
Since the magnetron 3 and the heat generating conductor 4 are collectively installed on the floor side of the heating chamber 1, the installation space for them can be made smaller than in the conventional example, which contributes to downsizing of the apparatus.

Further, since the microwave emitted from the magnetron 3 is blocked by the shield member 7 to prevent the heating conductor 4 from being irradiated, the phenomenon in which the heating conductor 4 abnormally generates heat by the microwave can be avoided. This contributes to improving the durability of the heat generating conductor 4.

Further, since the nets 7b and 7c are used for the shield member 7 accommodating the heat-generating conductor 4, the radiant heat generated from the heat-generating conductor 4 is applied to the entire heating target 2 in the heating chamber 1. As a result, it is possible to effectively prevent the occurrence of uneven heating, for example, it is possible to substantially uniformly heat a wide range of the heating target 2.

It should be noted that the present invention is not limited to the above-described embodiment, and various applications and modifications are conceivable.

(1) Another embodiment of the shapes of the heat generating conductor 4 and the shield member 7 is shown in FIGS. 3 to 6.

First, in the embodiment shown in FIGS. 3 and 4, the heating conductor 4 and the shield member 7 covering the heating conductor 4 are illustrated as having a spiral shape. The microwave coupling portion 8 is integrally attached to the center of the shield member 7. Also in this case, magnetron 3
Is driven, the electromagnetic field of the microwave propagated from the waveguide 6 is coupled to the microwave coupling unit 8, and the shield member 7 connected to the microwave coupling unit 8 in a microwave manner is used as the radiation antenna. As a result, the microwave energy 10 is emitted from the outer periphery of the shield member 7 through the shelf 5 made of a dielectric material into the heating chamber 1. At this time, since the heat generating conductor 4 is covered by the shield member 7, the microwave is cut off by the shield member 7, and abnormal heat generation of the heat generating conductor 4 is avoided.

In the embodiment shown in FIGS. 5 and 6, the shield member 7 is a rectangular metal plate, and the heat-generating conductor 4 is accommodated therein. A microwave coupling portion 8 is attached to the center of the lower surface of the shield member 7. Here, since the shield member 7 is a rectangular plate, the microwave energy 10 emitted by the electromagnetic field distribution generated in the microwave coupling portion 8 below the shield member 7 is released into the heating chamber 1. Are provided at a plurality of required positions in the thickness direction. That is, in this case, when the magnetron 3 is driven, the electromagnetic field of the microwave propagated from the waveguide 6 is changed to the microwave coupling portion 8.
The shield member 7 which is coupled to the microwave and is microwave-connected to the microwave coupling portion 8 functions as a radiation antenna, so that the shield member 7 passes through the dielectric plate 5 from the through hole 7e of the shield member 7. As a result, the microwave energy 10 is released into the heating chamber 1. At this time,
Since the heating conductor 4 is covered by the shield member 7,
Since the microwaves are blocked by the shield member 7, abnormal heating of the heating conductor 4 is avoided.

(2) In addition to the above embodiment, as shown in FIG. 7, a shielding member 7 made of a metal rectangular plate containing a heating conductor 4 therein is installed on the floor of the heating chamber 1.
The present invention includes a structure in which a plurality of strip-shaped protruding pieces 11 for forming a surface acoustic wave line are provided on the upper surface of the shield member 7 in a comb-teeth shape. Specifically, at the center of the above-described shield member 7, a through hole 7f penetrating in the thickness direction is provided. The microwave coupling portion 8 is provided in the through hole 7f.
Are inserted, and the microwave coupling portion 8 is joined to any one of the strip-shaped protrusions 11. In this case, the point that the heat generating conductor 4 is protected from the microwave by the shield member 7 is similar to the above-described various embodiments, Microwave energy 10
Is released into the heating chamber 1 in the second embodiment. Since this surface wave heating mode is well known as shown in Japanese Patent Application Laid-Open No. 4-284393, a detailed description thereof will be omitted.

By variably adjusting the height dimension and the separation pitch of the strip-shaped protruding pieces 11, the emission form of the surface wave heating energy can be controlled.

(3) In the microwave oven described in the above embodiment, as shown in FIG. 8, the heating conductor 4 may be shaped to take a character string, for example. In this case, when the heating conductor 4 (not shown) is driven, the character string 15 as shown in the drawing emerges from the radiant heat from the heating conductor 4, and the radiant heat can heat the heating target 2. Here, if the to-be-heated object 2 is a toast pan or the like, the toast pan can be provided with a character string in accordance with the shape of the heat generating conductor 4 so that entertainment can be enhanced.

(4) For the microwave oven described in the above embodiment, for example, in order to facilitate recycling after disposal, the power supply line may have the following structure. FIG. 9 shows a power supply line 20 of the microwave oven, and a plug 21 is attached to a tip of the power supply line 20. The power supply line 20 includes a plurality of electric wires 22, 22 and a cut line 23 made of an insulating material, which are bundled with the outer resin coating 2.
It has a structure covered with 4. These electric wires 22, 22
It has a structure in which the conductive wire 22a is covered with a resin film 22b, and the tear line 23 has a substantially triangular cross section. With such a power supply line 20, when disposing of electric equipment such as a microwave oven, the electric wires 22, 22 can be easily separated and taken out. That is, after the power supply line 20 is removed from the electric device, the plurality of electric wires 22 of the power supply line 20 are grasped, and only the tear line 23 is pulled. Since the coating 24 is torn, the outer resin coating 2
4 and a plurality of electric wires 22 can be easily separated.

Further, as shown in FIG. 10, the above-mentioned electric wires 22 and 22 may have a structure in which the above-described insulating material tear line 25 is inserted into the resin coating 22b together with the conducting wire 22a. it can. In this case, if the conductor 22a of the electric wire 22 is grasped and only the tear line 25 is pulled, the sharp corners of the tear line 25 will cut the resin coating 22b. Can be easily separated.

By the way, in the case of the power supply line 20 described above,
The following can be devised as a form to be attached to the electric device. That is, the power cable 20 is passed through the through hole of the frame 30 of the electric device, and the outer resin coating 24 is peeled off on the inner side of the frame 30 so that the plurality of electric wires 22 and 22 and the tear line 23 are exposed. The tip of the tear line 23 is connected to a required position of the frame 30 with a screw 31. In this case, even when an excessive load acts on the power supply line 20, the tear line 23 fixed to the frame 30 bears the above-mentioned load, so that no load is applied to the electric wires 22 and 22. Therefore, the disconnection of the electric wires 22, 22 is avoided.

As described above, if the structure of the power supply line 20 is devised, the processing for recycling can be easily performed and the power supply line 20 can be protected.

[0040]

According to the first to fourth aspects of the present invention, the magnetron, the waveguide, and the heat generating conductor are collectively installed on the ceiling or floor side of the heating chamber in order to achieve space saving and downsizing of the apparatus. The problem that has occurred, that is, abnormal heating of the heating conductor due to microwaves when using the magnetron and uneven heating of the heating target when using the heating conductor can be appropriately avoided.

In particular, according to the second aspect of the present invention, since the radiant heat generated from the heat generating conductor can be applied to the entire heating target in the heating chamber, it is possible to substantially uniformly heat a wide range of the heating target. For example, it is advantageous in improving the heating efficiency by preventing the occurrence of uneven heating.

According to the third aspect of the present invention, the coupling strength of the electromagnetic field of the microwave propagated from the magnetron via the waveguide to the microwave coupling portion attached to the shield member used as the radiation antenna is adjusted. This is advantageous in practical use, for example, it can be improved as much as possible.

According to the fourth aspect of the present invention, since the length of the leg of the shield member used as the radiation antenna is defined, the intensity of the electromagnetic field generated by the microwave coupling portion can be optimized. In addition, the microwave energy released to the heating chamber can be efficiently transmitted to the object to be heated, which contributes to the improvement of the heating efficiency.

[Brief description of the drawings]

FIG. 1 is a front view showing the internal configuration of a microwave oven according to an embodiment of the present invention.

FIG. 2 is a perspective view of a shield member in FIG. 1;

FIG. 3 is a front view showing the internal configuration of a microwave oven according to another embodiment of the present invention.

FIG. 4 is a perspective view of a shield member in FIG. 3;

FIG. 5 is a front view showing the internal configuration of a microwave oven according to another embodiment of the present invention.

FIG. 6 is a perspective view of a shield member in FIG. 5;

FIG. 7 is a front view showing the internal configuration of a microwave oven according to another embodiment of the present invention.

FIG. 8 is a perspective view showing the inside of a microwave oven according to another embodiment of the present invention.

FIG. 9 is a perspective view showing a power supply line provided in a microwave oven or the like.

FIG. 10 is a perspective view showing an application example of the power supply line of FIG. 9;

FIG. 11 is a perspective view showing a use form of the power supply line of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating room 2 Heating object 3 Magnetron 3a Magnetron antenna 4 Heating conductor 5 Shelf board 6 Waveguide 7 Shield member 8 Microwave coupling part 10 Microwave energy

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (4)

[Claims] 1. A high-frequency heating apparatus for heating and cooking an object to be housed in a heating chamber by microwaves or radiant heat, wherein the heating apparatus is installed on a magnetron emitting microwaves or on a ceiling or a floor of the heating chamber. A heat-generating conductor that emits radiant heat through the waveguide, a waveguide that is provided adjacent to the heating chamber near the installation location of the heat-generating conductor, and that propagates microwaves emitted from the magnetron antenna to the vicinity of the heat-generating conductor, A metal shield member configured to shield the heating conductor against microwaves emitted from the heater and to emit radiant heat emitted from the heating conductor to the heating chamber side,
A microwave coupling unit attached to the shield member and coupled to an electromagnetic field of microwave emitted from the magnetron, wherein the shield member is used as a radiation antenna for emitting microwaves to the heating chamber side by the microwave coupling unit. A high-frequency heating device, characterized in that: 2. A high-frequency heating apparatus according to claim 1, wherein said shield member has a metal cylindrical frame in which a heat generating conductor is housed, a metal net attached to upper and lower openings thereof, and a cylindrical frame. Are provided at several places around the circumference of the heating chamber and have legs for floating the cylindrical frame with respect to the heating chamber. A high-frequency heating device to which the microwave coupling unit is attached. 3. The high-frequency heating device according to claim 2, wherein the microwave coupling portion protrudes into the inside of the waveguide, and an outer peripheral surface of a cylindrical frame of the shield member from a lower end of the microwave coupling portion. Is λ / 2 or λ
A high-frequency heating device, wherein the length is set to an integral multiple of / 2. 4. The high-frequency heating device according to claim 2, wherein the leg of the shield member has an infinite impedance in which a shield member serving as a radiation antenna is floated without being grounded to the heating chamber. The total length of the part is λ / 4,
Alternatively, the high-frequency heating device is set to a length that is an integral multiple of λ / 4 + λ / 2.