JPS63172827A - High frequency heating appliance - Google Patents

Abstract

PURPOSE:To reduce heating irregularities by providing a metallic reflector in a gap between the bottom surface part and rotary tray of a heating chamber, and rotating the reflection plate by utilizing the shaft driving force of a driving part rotating the rotary tray. CONSTITUTION:A microwave radiated from a radiation antenna of a magnetron is transmitted through a wave guide 3 and is radiated into a heating chamber 5 through a coupling hole 4. In the interior of the heating chamber 5, the microwave repeats its reflection between the inner wall of the heating chamber 5 and a metallic reflector 14, whereby a standing wave is formed and intenseness and weakness occurs in energy distribution depending on the difference in location. However, the reflection plate 14 has a negative gentle slope from a part A to a part B and a positive gentle slope from the part B to the port A and further rotates with the rotation of the rotary tray 8. Therefore, the reflecting direction of the incident microwave, on the reflector 14 varies with the rotation of the reflector 14. In addition to the effect obtained by the rotation of a food 9 itself, it is possible to obtain more heating uniformity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device that reduces uneven heating of an object to be heated (hereinafter referred to as food) and achieves uniform heating with a simple configuration.

Conventional technology In high-frequency heating equipment, in order to prevent food from being browned and to perform good and efficient cooking, the heating chamber and waveguide installation must be designed to ensure uniform heating. It is necessary to do it.

In general, in the case of dielectric heating using high frequency, the amount of heat generated per unit volume and unit time inside the food, P, is calculated using the following formula (%), where K is a proportionality constant, and f is the frequency of the high frequency (hereinafter referred to as microwave) (electronic 2460MHz for range), ε
1 is the real part of the dielectric constant of the food, tanδ is the dielectric constant, E
is the electric field inside the food.

In equation (1), fsε1 and tanδ are constants determined by the food, so in order to achieve uniform heating, it is necessary to make the electric field intensity IEI inside the food as uniform as possible.

Conventionally, as a means to uniformize the electric field strength and reduce uneven heating, a rotating plate is installed on the floor of the heating chamber, and the electric field strength inside the food is adjusted by placing the food on the rotating plate and rotating it during heating. Many methods have been used to periodically vary the distribution, or to spread the microwaves irradiated from a waveguide by installing rotating metal blades in the heating chamber.

Hereinafter, a conventional method for reducing heating unevenness described above will be described with reference to the drawings.

FIGS. 3 and 4 are diagrams showing conventional examples of methods for reducing uneven heating. First, in Fig. 3, 1 is a high-frequency oscillator (hereinafter referred to as a magnetron), 2 is a radiation antenna of the magnetron 1, 3 is a waveguide that serves as a transmission path for the microwaves radiated from the antenna 2, 6 is a heating chamber, and 4 is a guide. A coupling hole for coupling the wave tube 3 and the heating chamber 6 at high frequency; 8 is a rotating plate for placing food; 6 is a drive unit for rotating the rotating plate 8; 7 is a connection hole from the drive unit 6; A shaft 9 for transmitting torque to the rotating plate 8 is a food dielectrically heated by microwaves.

In the high-frequency heating device configured as described above, microwaves radiated from the radiation antenna 2 coupled to the magnetron 1 propagate through the waveguide 3 to the coupling hole 4, and from the coupling hole 4 to the inside of the heating chamber 6. radiated to. On the other hand, the rotating plate 8 placed inside the heating chamber 6 rotates together with the food 9 placed on the rotating plate 8 by receiving torque generated by the drive unit 6 via the shaft 7 . By the way, heating chamber 6
When the inside is irradiated with microwaves, a standing wave mode is generated inside the heating chamber 6 due to the interference of the microwaves that have been reflected many times on the inner wall surface. For this reason, there is a distribution of strength and weakness in the electric field strength, which causes uneven heating of the food. In the above configuration, by rotating the food 9, the electric field strength distribution inside the food 9 is changed, thereby reducing uneven heating.

Next, in FIG. 4, another conventional structure will be explained. 12 is a metal blade (hereinafter referred to as a stun) placed inside the heating chamber 5, 11 is a shaft for rotational driving, and 10
3 is a drive section, and the other components are the same as those shown in FIG. 3.

In the high-frequency heating apparatus shown in FIG. 4 configured as described above, the microwave inside the heating chamber 6 is expanded by rotating the stun 12 via the shaft 11 by the drive unit 1o. The generation of standing wave modes inside the heating chamber 5 is reduced, and the microwaves are uniformly diffused inside, thereby reducing uneven heating.

Problems to be Solved by the Invention However, the standing wave mode of microwaves generated inside the heating chamber strongly depends on the spatial shape of the heating chamber. Although it is averaged in the radial direction, it is difficult to average it in the radial direction, so a problem may occur if, for example, the periphery is well heated but the center is half-baked.

Furthermore, even with the configuration shown in Figure 4, in order to reduce the generation of standing waves, the typical dimensions of the blades that make up the stun must be considerably larger than the microwave wavelength (spatial wavelength 12.2 cM). However, in a microwave oven equipped with a heater etc., it was practically difficult to arrange such a large stun due to space factors and other considerations.

In view of the above-mentioned problems, an object of the present invention is to provide an excellent high-frequency heating device with less uneven heating by uniformly diffusing microwaves inside a heating chamber with a simple configuration.

Means for Solving the Problems In order to solve the above-mentioned problems, the high-frequency heating device of the present invention provides a metallic reflector between the bottom of the heating chamber and the rotary plate, and a drive unit that rotates the rotary plate. The reflector is rotated using the shaft driving force of the reflector.

Function The present invention has the above-mentioned configuration, and in addition to the uniform heating effect achieved by the rotational movement of the food by the rotating plate, a metal reflecting plate with a relatively large area is installed at the bottom of the rotating plate, and this is rotated together with the rotating plate. By doing so, the microwaves transmitted into the heating chamber are reflected many times between the walls of the heating chamber and the reflection plate, causing the standing waves to change moment by moment as the reflection plate rotates, causing waves to be generated inside the food. By temporally averaging the electric field energy distribution, it is possible to further improve the uniformity of heating.

EXAMPLE Hereinafter, a high-frequency heating device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a high frequency heating device in one embodiment of the present invention. In Figure 1, magnetron 1° radiation antenna 2
．． Waveguide 3. Binding hole 4. Heating chamber 6° drive unit 6. The shaft 7, rotating plate 81 and food 9 are the same as those shown in FIG. Reference numeral 15 denotes a part of the bottom of the heating chamber 6, which is a concentric recessed space. Reference numeral 14 denotes a metal reflecting plate, which is held below the rotary plate 8 and arranged so as to fit into the recessed space 16.

FIG. 2 is a diagram showing the detailed configuration of the reflector 14.
Reference numeral 4 denotes a metal plate portion 17 and a spacer 13, and a fastening member 16 that fastens the spacer 13 and the metal plate 17.
It consists of The spacer 13 has a hole with a key groove in its center, through which the shaft 7 for transmitting the driving force from the drive section 6 passes, and is configured to rotate together with the rotary plate 8 in the recessed space. In Fig. 2, the money attribute plate 17 has different heights between parts A and B, and has a negative slope from part A to part B, and a positive slope from part B to part A. is attached.

In the high-frequency heating device configured as described above, microwaves radiated from the radiation antenna 2 of the magnetron 1 are transmitted through the waveguide 3 and radiated through the coupling hole 4 into the heating chamber 6. . Inside the heating chamber 6, the microwaves are repeatedly reflected between the heating chamber walls and the metal reflection plate 14 to form a standing wave, and the electric field energy distribution varies in strength depending on the location. . However, as shown in FIG.
There is a smooth negative slope from part B to part B, and a smooth positive slope from part B to part B. Furthermore, since the plate rotates with the rotation of the rotating plate 8, the direction of reflection of the microwave incident on the reflection plate 14 is It will gradually change as the plate 14 rotates.

Moreover, since the reflector plate 14 is arranged in the recessed space between the rotary plate 8 and the bottom of the heating chamber 6, it does not occupy the actual space where food is placed and is space-saving. Since the area of the metallic plate 1a can be large, its influence on the formation of standing waves is large. Therefore, it is considered that the standing wave distribution formed inside the heating chamber 6 repeats periodic changes from time to time as the reflection plate 14 rotates. As a result, the electric field energy distribution inside the food 9, that is, the distribution of electric field energy strength depending on the location, changes from moment to moment.
In addition to the effect of rotation of the food 9 itself, further heating uniformity can be obtained.

In addition, in FIG. 2, the metal plate 17 is composed of one plate, but it may be divided into a plurality of blade-shaped plates. Furthermore, in the configurations shown in FIGS. 1 and 2, the metal plate 17 rotates at the same number of rotations as the rotary plate 8;
An appropriate speed reduction mechanism may be provided to rotate at different rotational speeds.

Effects of the Invention The present invention provides a method for reducing the electric field generated inside the heating chamber by arranging, for example, a metallic reflective plate in the gap between the bottom of the heating chamber and the rotary plate, and rotating this reflective plate when heating an object to be heated. The present invention realizes a high-frequency heating device that can uniformly heat the food by changing the standing wave pattern from time to time to average the electric field energy distribution inside the food, and combining this with the uniform effect of the rotation of the food itself.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a high-frequency heating device according to an embodiment of the present invention, Fig. 2 is an exploded perspective view of main parts showing the detailed structure of the reflector, and Figs. 3 and 4 are conventional high-frequency heating devices. FIG. 2 is a cross-sectional view of the device. 1... Magnetro/, 2... Radiation antenna, 3... Waveguide, 4... Coupling hole,
6... Heating chamber, 6... Drive section, 7...
...Shaft, 8... Rotating plate, 9...
...Food, 10...Drive unit, 11...
Shaft, 12...Stan, 13...
Spacer, 14...Reflector, 15...
Hollow space, 16... Fastening member, 17...
...Metal plate. Name of agent: Patent attorney Toshio Nakao and 1 other person Total height: 14cm - Ittan-Binchohon (4,32 Figure 2)

Claims (1)

[Claims] The device includes a heating chamber, a high-frequency oscillator, a waveguide that guides the high-frequency power output from the high-frequency oscillator to the heating chamber, a rotating plate on which an object to be heated is placed, and a drive unit that rotates the rotating plate. A high-frequency heating device characterized in that a reflecting plate is provided in a gap between the bottom of the heating chamber and the rotating plate, and the reflecting plate is rotated together with the rotating plate by an axial driving force of the driving section.