JPS58181292A - High frequency heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency heating device that connects a waveguide and a heating chamber through an opening and has a stirrer.

Conventionally, exciting a standing wave mode that mainly has a vertical electric field component in the heating chamber of a high-frequency heating device has been used in microwave ovens, etc., because the standing wave mode is stably excited under various loads. This is a very important condition for improving the distribution of food heating equipment. However, as shown in Fig. 1, when the high-frequency electromagnetic waves from the magnetron 1, which is a high-frequency oscillator 3t'-', are coupled to the heating chamber 4 through the waveguide 2 and the opening 3, the direction of the electric field 5 changes horizontally at the opening 3. , a standing wave mode having a vertical electric field could not be excited in the heating chamber 2.

Further, when the waveguide 2 and the heating chamber 4 are coupled by an antenna 6 as shown in FIG. 2, it is possible to excite a standing wave mode having a vertical electric field 5 in the heating chamber 4. However, with this structure, the tip of the antenna 6 protrudes into the heating chamber 4, which not only reduces the effective volume of the heating chamber 4, but also causes spark discharge in the high-frequency electric field if the antenna 6 comes into contact with food particles.

Furthermore, since the antenna 6 is required, the configuration becomes complicated, leading to an increase in cost.

In addition, in the standing wave mode, which has a change in electric field strength between even and odd numbers, when the load is placed at the center, the center is strongly heated and the center is weakened due to radio wave absorption, etc., and the distribution is corrected. Although the uniformity was good, this standing wave mode could not be excited from the center because there was no electric field at the center of the heating chamber 4. 1. Therefore, when multiple loads were placed, each load would be heated to a different degree. Furthermore, the directionality of the radio waves from the high-frequency oscillator also occurred, resulting in a difference in the degree of heating between the side of the heating chamber where the high-frequency oscillator was attached and the opposite side.

An object of the present invention is to improve the power/heat distribution by exciting a standing wave mode in the heating chamber in a configuration in which the waveguide is connected to the heating chamber by opening the waveguide.

The purpose is to obtain stable distribution performance even with load fluctuations that excite standing wave modes with vertical electric fields.

In order to achieve the above object, the present invention provides a plurality of heating chambers with different dimensions in which the dimensions of the heating chamber are such that the standing wave mode resonates, and the electric field direction and position of the standing wave mode are made to match the electric field direction and position of the waveguide. By having this opening, it is possible to excite the standing wave mode that cannot be excited from the center of the heating chamber wall, and also eliminate the directionality of the radio waves of the high frequency oscillator, making it possible to heat multiple loads at the same time. be.

Hereinafter, an embodiment of the non-invention will be described based on the drawings.
Nee: Explain.

In FIG. 3, a door 7 is provided so that it can be opened and closed by a handle 8, and an f-control knob 9 can control the oscillation of a magnetron 1, which is a high frequency oscillator. In addition, since this embodiment is designed to heat the air using gas or electricity and can also be used for cooking in an oven, a temperature control knob 10 is not provided.
ing.

In FIG. 4, high-frequency electromagnetic waves from a magnetron 1, which is a high-frequency oscillator, pass through a waveguide 2, pass through openings 3a and 3b, and enter a heating chamber 4. Air from a fan 11 for cooling the magnetron 1, electrical parts, etc. enters the heating chamber 4, rotates a stirrer 12 that stirs the radio waves, and exits to the outside of the incorporeal body.

- The dimensions of the heating chamber 4 are based on the formula: Here, λ is the wavelength, and Person+B+C are the width, depth, and height dimensions of the heating chamber 4, m, and n.

p is the number of changes in the electric field of the standing wave mode that occur in each direction of the wave, and is an integer. One example of implementation of the present invention. In case. -4,. -5, choose p-81. If λ6 beanie' = 122 mm, A = 290 mm, B = 2
It will be about 90mm.

FIG. 5 is a diagram schematically showing a cross section taken along line XX in FIG. 4. In FIG. 6, there are standing wave modes 4 and 5 in the heating chamber 4.
．． O mode is occurring. This knife has four electric field changes in the width direction, five electric field changes in the depth direction, and no electric field changes in the height direction, so all electric fields 5 are vertical. This electric field 6 is schematically indicated by ■ or ■.
indicates that the image is facing upwards from the paper surface, and ■ indicates that it is facing downwards from the paper surface. 4
5. The heating pattern portion 13 in the O mode looks like a hatched area, and the center of the heating chamber 4 is heated strongly.

Furthermore, since the heating pattern portion 13 is regular, it can be heated more uniformly by thermal conduction or stirring by the stirrer 12 or the like. Further, the width of the waveguide 2 is selected so as to be the same as the settled wave mode in the heating chamber 4. and openings 3a, 3b
A plurality of are provided, and each one is located at the maximum electric field point, and the sizes of the aperture 31L and the aperture 3b are slightly changed, so that the magnetron 1 has a standing wave due to the directivity of the radio waves 7-'-' etc. This prevents distortion of mode symmetry and ensures uniform heating even when multiple loads are applied. Further, a short circuit portion 14 is provided in the openings 3a and 3b so that a horizontal electric field is not generated in the openings 3a and 3b.
It is designed to excite only the vertical electric field. To confirm this, a heat-sensitive material is applied to the cardboard 16, and when the cardboard 15 is heated by the electric field, the color of the heat-sensitive material changes at t1. For example, when the cardboard 15 is placed on the surface DD in FIG. 5, the discolored portion 16 becomes as shown in FIG. 6.

As described above, the present invention provides the following effects.

(1) Since it is a standing wave mode that strengthens the center, it prevents the center of the load from becoming weaker in heating due to absorption of radio waves, resulting in good uniformity.

(2) Since it has a plurality of apertures that match the electric field of the standing wave mode, there is no interference of radio waves between the apertures.

(3) Since the amount of radio wave radiation is adjusted by changing the size of multiple apertures, the symmetry of the standing wave mode is improved and the directivity of the magnetron is eliminated, so even with a small load, one side will not heat up strongly. Multiple loads cannot be applied unevenly.

(4) Since there is only a vertical electric field, there is little change in distribution with respect to changes in load.

(5) Distribution performance is further improved by combining silk with stirrer etc.

(6) Since the structure is very simple since there is only one opening, it can be manufactured at low cost.

(7) Since a standing wave mode occurs, even if the load changes, there is little change in impedance from the magnetron, so output efficiency is good.

(8) Even when there is no load, the radio waves are transmitted into the Calothermal chamber, so there is little reflection and there is no adverse effect on the magnetron.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a conventional high-frequency heating device, FIG. 2 is a front sectional view of another conventional high-frequency heating device, and FIG. 3 is an external perspective view of a high-frequency heating device that is an embodiment of the invention. Fourth
The figure is a front sectional view of the same device, Figure 5 is a state diagram showing the state of the electric field of the same device, and Figure 6 9'''-' is the state of a test paper showing the experimental results of the electric field pattern due to high frequency electromagnetic waves of the same device. It is a figure. 1... High frequency oscillator, 2... Waveguide,
3a, 3b...Opening, 4...Heating chamber, 14...Short circuit part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 2 Figure 3 Figure 7 10 Figure 4 Figure 5 Figure 6 Figure 6

Claims (1)

[Scope of Claims] (1) A heating chamber for storing an object to be heated, a high-frequency oscillator for feeding high-frequency electromagnetic waves into the heating chamber, and a waveguide for coupling the heating chamber and the high-frequency oscillator, The waveguide and the heating chamber are coupled through a plurality of openings, the electric field position and direction of the standing wave mode in the heating chamber are made to match the electric field direction and position of the waveguide, and the standing wave mode is A high-frequency heating device configured to provide the plurality of openings at the maximum electric field point. (2) The high-frequency heating device according to claim 1, wherein the plurality of openings are configured to have different sizes. (3) Claim 1, wherein the opening is provided with a short-circuit portion parallel to the traveling direction of the high-frequency electromagnetic wave of the waveguide.
The high-frequency heating device described in Section 1. (4) The high-frequency two-beam heating device according to claim 1, wherein the plurality of openings are provided on the upper surface or the lower surface of the heating chamber. (6) Claim 1 in which the rotating shaft of the rotating stirrer is provided approximately at the center of the heating chamber wall having an opening.
The high-frequency heating device described in Section 1. (6) The high-frequency heating device according to claim 4, wherein the standing wave mode is configured to change the strength of an even number of electric fields in the width direction of the heating chamber and an odd number of electric fields in the depth direction. ('7) The high-frequency heating device according to claim 1, wherein the standing wave mode has a vertical electric field.