JP2007042333A - High frequency heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency heating device giving little uneven heating to an object to be heated. <P>SOLUTION: In this high frequency heating device equipped with a heating chamber to house an object to be heated, a plate fixed in the lower part of the heating chamber and made of a dielectric, on which the object to be heated is placed, a high frequency supply chamber provided in the heating chamber on the lower side of the plate, a magnetron for generating high frequency energy to heat the object to be heated, a wave guide for guiding high frequency energy generated from the magnetron to the high frequency supply chamber, a connecting hole provided between the high frequency supply chamber and the wave guide to radiate the high frequency energy guided by the wave guide to the high frequency supply chamber, a rotary antenna provided in the high frequency chamber to diffuse the high frequency energy radiated from the connecting hole, and a driving means to rotationally rotate the rotary antenna, the rotary antenna 9 is formed in a spiral shape, a funnel shape, or a shape obtained by compounding them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-frequency heating device (microwave oven) that heats a non-heated object such as food by applying high-frequency energy, and particularly relates to the shape of a rotating antenna for diffusing high-frequency energy during heating.

  As shown in FIG. 7, a conventional general high-frequency heating apparatus includes a heating chamber 2 that accommodates an object to be heated 1, a non-heated object mounting plate 3 made of a dielectric material fixed to the lower portion of the heating chamber 2, From the high-frequency supply chamber 4 provided at the center of the bottom of the heating chamber 2 below the non-heated object placing plate 3, a magnetron 5 for generating high-frequency energy for heating the object to be heated 1, A waveguide 6 that guides the generated high-frequency energy to the high-frequency supply chamber 4, and is provided between the high-frequency supply chamber 4 and the waveguide 6, and radiates the high-frequency energy guided by the waveguide 6 to the high-frequency supply chamber 4. A coupling hole 7, a central conductor 8 provided through the coupling hole 7, and a high frequency supply chamber 4 connected to the central conductor 8 to diffuse high frequency energy radiated from the coupling hole 7. Rotating antenna 9 and center conductor 8 and conductor A dielectric shaft 10 which is connected by a tube within 6 is configured to include a motor 11 as a driving means for rotationally driving the rotating antenna 9 is connected with the dielectric axis 10.

In this conventional high-frequency heating device, the shape of the rotating antenna 9 for diffusing high-frequency energy is, for example, a strip shape as shown in FIG. The shape is a combination of flat metal plates, or a shape obtained by cutting out a metal disc into a circle, rectangle, fan, or the like as shown in FIG.
JP-A-6-36874 JP 2002-286229 A

  However, in the conventional high-frequency heating apparatus including the rotary antenna having the above shape, the distribution of the high-frequency energy radiated from the rotary antenna to the heating chamber is not uniform, so that food such as food placed on the heated object placing plate is covered. There is a problem that uneven heating (the central part of the object to be heated is weak and the outer peripheral part is heated strongly, or conversely, the central part is strong and the outer peripheral part is heated weakly) is likely to occur. .

  The present invention has been made in view of such problems, and an object of the present invention is to provide a high-frequency heating device with little heating unevenness to an object to be heated.

  In order to achieve the above object, the present invention provides a heating chamber that accommodates an object to be heated, a non-heating object mounting plate made of a dielectric fixed to the lower part of the heating chamber, and a non-heating object mounting plate. On the lower side, a high-frequency supply chamber provided in the heating chamber, a magnetron that generates high-frequency energy for heating an object to be heated, a waveguide that guides high-frequency energy generated from the magnetron to the high-frequency supply chamber, A coupling hole that is provided between the high-frequency supply chamber and the waveguide and that radiates high-frequency energy guided by the waveguide to the high-frequency supply chamber; and provided in the high-frequency supply chamber, from the coupling hole In a high-frequency heating device comprising a rotating antenna that diffuses radiated high-frequency energy and a driving means that rotationally drives the rotating antenna, the shape of the rotating antenna is spiral or It is characterized in that it has formed Doo shape. The rotating antenna may be formed in a funnel shape and provided with a spiral slit.

  In the high-frequency heating device of the present invention, the rotating antenna for diffusing high-frequency energy is formed in a spiral shape, so that the helical rotating antenna rotates, so that the high-frequency energy is uniformly diffused and efficiently radiated. Uneven heating with respect to the object to be heated can be reduced. Furthermore, in the configuration in which the rotating antenna has a funnel shape, by appropriately selecting the aperture depth of the funnel-shaped rotating antenna, the radiation directivity of the high frequency energy from the rotating antenna can be controlled and adjusted to an ideal heating form. Therefore, it is possible to provide a high-frequency heating device with little heating unevenness.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of an essential part of a high-frequency heating device (microwave oven) showing a first embodiment of the present invention. This high-frequency heating device includes a heating chamber 2 for storing an object to be heated 1 and a heating chamber 2. A non-heated object placing plate 3 made of a dielectric fixed to the lower part, a high-frequency supply chamber 4 provided at the center of the bottom of the heating chamber 2 below the non-heated object placing plate 3, and the object to be heated 1 A magnetron 5 for generating high-frequency energy for heating the substrate, a waveguide 6 for guiding the high-frequency energy generated from the magnetron 5 to the high-frequency supply chamber 4, and the high-frequency supply chamber 4 and the waveguide 6. The coupling hole 7 that radiates the high-frequency energy guided by the waveguide 6 to the high-frequency supply chamber 4, the central conductor 8 provided through the coupling hole 7, and the high-frequency supply chamber connected to the central conductor 8 4 and the high frequency energy radiated from the coupling hole 7 A rotating antenna 9 for diffusing the load, a central shaft 8 and a dielectric shaft 10 connected in the waveguide 6, and a motor 11 which is connected to the dielectric shaft 10 and is a driving means for driving the rotating antenna 9 to rotate. And is configured.

  In the high-frequency heating apparatus of this example configured as described above, high-frequency energy generated in the magnetron 5 is supplied to the rotating antenna 9 through the waveguide 6, and here, the coupling hole 7, the central conductor 8, and the waveguide 6. The coaxial waveguide converter is configured to convert the TE10 transmission mode transmitted through the waveguide 6 into the TEM transmission mode and supply high-frequency energy to the rotating antenna 9. Then, high-frequency energy is diffused from the rotating antenna 9 and radiated into the heating chamber 2, whereby the object to be heated 1 on the non-heated object placing plate 3 is heated. Here, the material of the rotating antenna 9 is preferably aluminum with low energy loss and good heat dissipation.

  FIG. 2 is a plan view of the rotating antenna 9 provided in the high-frequency heating device of FIG. The rotating antenna 9 is configured by providing a spiral slit 9a formed in a spiral shape from the center of rotation to the vicinity of the outer periphery on a circular circular plate made of metal, thereby forming a spiral shape as a whole. ing.

  Since the rotating antenna 9 is formed in a spiral shape in this way, in the high-frequency heating device of this example, the rotating rotating antenna 9 rotates, so that the high-frequency energy is uniformly diffused and efficiently radiated. It is possible to suppress the occurrence of heating unevenness to the heated object 1 (the central part of the object to be heated is weak and the outer peripheral part is heated strongly, or conversely, the central part is strong and the outer peripheral part is heated weakly). Is.

  FIG. 3 is a cross-sectional view of an essential part of a high-frequency heating apparatus showing a second embodiment of the present invention. The basic configuration is the same as that of the first embodiment of FIG. It is formed in a funnel shape (horn shape opening in a trumpet shape). In this case, the funnel-shaped rotary antenna 9 is connected to the center conductor 8 with the opening side facing upward, ie, the heating chamber 2 side, and the depth (height) of the diaphragm is about 5 mm. Further, as shown in FIG. 4, the funnel-shaped rotating antenna 9 may be provided with a spiral slit 9a.

  In the configuration in which the rotating antenna 9 has a funnel shape as described above, the radiation directivity of high-frequency energy from the rotating antenna 9 is controlled by appropriately selecting the aperture depth of the funnel-shaped rotating antenna 9. Heating unevenness to the heated object 1 that has occurred (the central part of the heated object is weak and the outer peripheral part is heated strongly, or conversely the central part is strong and the outer peripheral part is heated weakly) The heating can be performed so that the center part, which is said to be an ideal high-frequency heating mode, is heated on average.

  In this case, whether the heating of the central part of the article 1 to be heated is strong or weak depends largely on the shape of the heating chamber 2, so that the opening direction of the funnel-shaped rotary antenna 9 is on the heating chamber side or the opposite direction. For example, the opening direction of the rotating antenna 9 is determined by the shape of each heating chamber 2.

  The rotating antenna 9 shown in FIG. 4 is of a kind called a spiral antenna in terms of a general antenna shape. When the heating of the central portion of the object to be heated is weak due to the radiation characteristics of the antenna, the rotating antenna 9 is used. The opening side of the rotating antenna 9 is installed so that the opening side of the rotating antenna 9 faces the coupling hole 7 side. Then, by appropriately selecting the aperture depth of the funnel-shaped rotary antenna 9, the high-frequency energy radiation directivity from the rotary antenna 9 is controlled to finely adjust the radiation characteristics.

  FIG. 5 is a view showing the temperature distribution analysis result of the object to be heated in the high-frequency heating apparatus of the first embodiment shown in FIG. 1 (on the AA cross section at the almost center height of the object 1 to be heated shown in FIG. FIG. 6 is a diagram showing the temperature distribution analysis result of the object to be heated in the high frequency heating apparatus of the second embodiment shown in FIG. 3 (at the substantially center of the object 1 to be heated shown in FIG. 3). (Planar temperature distribution of AA cross section at height).

Here, frozen pizza pie is assumed as the object to be heated 1, and the physical constants at the time of analysis are calculated as a relative permittivity of 4.4, an electrical conductivity of 0.0722 (s / m), and a density of 794 (kg / m ³ ). did. In FIG. 5 and FIG. 6, the bright part shows that the temperature rise is high, and the dark part shows that the temperature rise is low.

  As is apparent from this temperature distribution, in the case of the first embodiment in which the rotating antenna 9 is formed in a spiral shape (FIG. 5), the temperature of the object to be heated increases substantially symmetrically on the front, back, left and right, and the central portion The distribution is slightly low. On the other hand, in the case of the second embodiment in which the rotating antenna 9 is formed in a funnel shape (FIG. 6), the temperature of the heated object is high at the center, and the temperature of the other parts is almost average. Distribution. In the case of this funnel-shaped rotating antenna, the size and position of the portion with a high temperature rise can be adjusted to an optimum state by appropriately selecting the aperture depth.

It is a longitudinal cross-sectional view of the principal part of the high frequency heating apparatus which shows the 1st Example of this invention. It is a top view which shows the example of a shape of a helical rotating antenna. It is a longitudinal cross-sectional view of the principal part of the high frequency heating apparatus which shows the 2nd Example of this invention. It is a perspective view which shows the example of a shape of a funnel-shaped rotary antenna. It is a figure which shows the temperature distribution analysis result of the to-be-heated material in the high frequency heating apparatus of a 1st Example. It is a figure which shows the temperature distribution analysis result of the to-be-heated material in the high frequency heating apparatus of a 2nd Example. It is a longitudinal cross-sectional view of the principal part of the conventional high frequency heating apparatus. It is an example of the shape of the rotating antenna used for the conventional high frequency heating apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Heated object, 2 ... Heating chamber, 3 ... Heated object mounting board, 4 ... High frequency supply chamber, 5 ... Magnetron, 6 ... Waveguide, 7 ... Coupling hole, 9 ... Rotating antenna, 9a ... Spiral shape Slit, 11 ... motor (drive means)

Claims (3)

  A heating chamber for storing an object to be heated, a non-heated object mounting plate made of a dielectric material fixed to the lower portion of the heating chamber, and a high frequency provided in the heating chamber below the non-heated object mounting plate A supply chamber; a magnetron that generates high-frequency energy for heating an object to be heated; a waveguide that guides high-frequency energy generated from the magnetron to the high-frequency supply chamber; and the high-frequency supply chamber and the waveguide A coupling hole that is provided between and radiates high-frequency energy guided by the waveguide to the high-frequency supply chamber; and a rotary antenna that is provided in the high-frequency supply chamber and diffuses high-frequency energy radiated from the coupling hole. And a driving means for rotating the rotating antenna, wherein the rotating antenna is formed in a spiral shape.   A heating chamber for storing an object to be heated, a non-heating object mounting plate made of a dielectric material fixed to the lower portion of the heating chamber, and a high frequency provided in the heating chamber below the non-heating object mounting plate A supply chamber; a magnetron that generates high-frequency energy for heating an object to be heated; a waveguide that guides high-frequency energy generated from the magnetron to the high-frequency supply chamber; and the high-frequency supply chamber and the waveguide A coupling hole that is provided between and radiates high-frequency energy guided by the waveguide to the high-frequency supply chamber; and a rotary antenna that is provided in the high-frequency supply chamber and diffuses high-frequency energy radiated from the coupling hole. And a driving means for rotating the rotating antenna, wherein the rotating antenna is formed in a funnel shape.   A heating chamber for storing an object to be heated, a non-heated object mounting plate made of a dielectric material fixed to the lower portion of the heating chamber, and a high frequency provided in the heating chamber below the non-heated object mounting plate A supply chamber; a magnetron that generates high-frequency energy for heating an object to be heated; a waveguide that guides high-frequency energy generated from the magnetron to the high-frequency supply chamber; and the high-frequency supply chamber and the waveguide A coupling hole that is provided between and radiates high-frequency energy guided by the waveguide to the high-frequency supply chamber; and a rotary antenna that is provided in the high-frequency supply chamber and diffuses high-frequency energy radiated from the coupling hole. Driving means for rotating the rotary antenna, and the rotary antenna is formed in a funnel shape and provided with a spiral slit. Wave heating device.