JPS6153839B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency heating device, particularly to a heating chamber structure.

For example, in the conventional microwave oven shown in FIG. 1, a magnetron 2 is installed in a heating chamber 1, and a radio wave stirring blade 3 is provided directly below the antenna of the magnetron 2, and the object to be heated is placed on a saucer 4 for the object to be heated. A partition plate 5 is provided to separate the portion occupied by the radio wave stirring blade 3 from the rotating portion of the radio wave stirring blade 3, and to protect the radio wave stirring blade 3. Generally, this partition plate 5 is an essential component, and a mounting plate 6 is used to hold this partition plate 5.
is provided on the upper surface of the heating chamber 1. However, this mounting plate 6 must firmly hold the partition plate 5 so that the radio-wave stirring blades 3 are protected even if a slight force is applied to the partition plate 5 during cleaning or the like. Figure 2 shows the heating chamber 1 viewed from the front opening side, but if the partition plate 5 is made of metal, the height of the upper part of the heating chamber 1 indicated by diagonal lines is approximately 40 to 50 mm.
The fourth wall is formed as a wall and serves as a reflector for radio waves.
The pre-intended resonance mode of the standing wave as shown in the figure did not appear, and the resonance mode as shown in Figure 5 occurred, causing uneven heating distribution and adversely affecting the quality of cooking. Conventionally, as a countermeasure to this kind of problem, as in the conventional example shown in FIG. Alternatively, the mounting plate 6 may be made of a special resin molded material that is radio wave transparent and has a relatively small dielectric loss that does not affect the resonance mode of standing waves. However, all of these configurations have drawbacks that make them undesirable. In other words, in the former case,
In the first place, if this kind of metal body is attached, the front and back depth dimensions of the heating chamber 1 for the purposely designed resonance mode of the standing wave as described above will collapse, and the intended resonance mode of the standing plate will be lost. This made it difficult to obtain desired cooking performance. Also, in the latter case, the objects to be heated generally get stuck, or
If the object to be heated is minute or if you forget to put it in, it may cause thermal deformation, or in some cases may melt or ignite, resulting in a fire. There were also things to do. Therefore, structures in the heating chamber 1 made of this type of resin material have generally been avoided as much as possible.

The present invention aims to eliminate such drawbacks and further improve cooking performance.

The present invention includes a heating chamber that stores an object to be heated and has a substantially rectangular parallelepiped shape, a high-frequency oscillator that is located approximately at the center of an upper wall surface of the heating chamber and feeds high-frequency waves into the heating chamber via an antenna, and A partition plate that protects an antenna portion of an oscillator, and a mounting plate that supports the partition plate on both sides, and the mounting plate has a vertical portion having a height of 1/6 or less of the wavelength of the high frequency wave. In addition, the mounting plate is a high frequency heating device located at the peak of the standing wave, and a stable resonance mode of the standing wave is obtained in the heating chamber.
This allows for more uniform heating.

Generally, the width, depth, and height of the heating chamber are a, respectively.
b and c, the resonance wavelength λ of the mode oscillating within the heating chamber is generally given by the following equation.

2 λ= …(1) (m/a) ² + (n/b) ² + (1/c) ² In the above formula 1, m, n, l are arbitrary integers, and the side lengths are a, b, The mode at this time is indicated by the wave number in each direction of c. From the experiment, we installed a magnetron approximately at the center of the front, back, left, and right sides in the a and b directions, set it to O without generating a mode in the height direction, and generated an odd number of wave numbers in the width and depth directions, and placed the magnetron at the peak of the standing wave. It is known that the output of the heating chamber with respect to the input of the magnetron, that is, the conversion efficiency, is maximized when the heating chamber is installed, and the present invention applies this principle to concrete practice.

An embodiment of the present invention will be described below based on the drawings.

6, 7, and 8, the heating chamber 1 has a standing wave generated inside, the wave number of the resonance mode is O in the height direction, and the wave numbers in the width direction and depth direction are odd numbers. The dimensions are set such that the magnetron 2 is positioned at the peak of the standing wave. A magnetron 2 is attached to the upper wall surfaces 7 and 12 of this heating chamber 1, and a radio stirring blade 3 is provided directly below the antenna of the magnetron 2. A partition plate 5 is provided on the side wall 8 of the heating chamber 1 to separate the space occupied by the object placed on the tray 4 of the object to be heated from the rotation space of the radio stirring blade 3 and to protect the radio stirring blade 3. It is attached to the mounting plate 9 which has been spot welded in advance. This mounting plate 9 is the 8th
As shown in the figure, the vertical part of the heating chamber 1 having a height l ₁ in the vertical direction is made of a metal material with a height of 1/6 or less of the wavelength λ of the high frequency power supplied to the heating chamber 1, and its mounting position is located at the peak of the standing wave. Therefore, within the heating chamber 1, there are hardly any walls or the like that act as reflectors for radio waves in the vertical direction. Therefore, it was confirmed through experiments that the front and rear depth dimensions b or the left and right width dimensions a of the heating chamber 1, which affect the resonance mode of the standing waves, were not affected at all and did not pose an obstacle. . Further, even though the width in the horizontal direction was 30 to 50 mm, which is almost the same as the conventional one, in this example, there was no effect on the desired resonance mode at all.

As described above, according to this embodiment, the pattern of the resonance mode of the standing wave in the depth direction in the heating chamber 1 was confirmed by the degree of discoloration of the thermocrayon.
As shown in FIG. 4, five resonance modes were clearly generated in the depth direction. This indicates that the radio waves within the heating chamber 1 are radiated more uniformly.

As explained above, according to the present invention, the following effects can be obtained.

(1) Since the mounting plate is located at the peak of the intended standing wave, even if a standing wave other than the intended standing wave is generated by the object to be heated, it is canceled out and a stable standing wave is created. A resonance mode is obtained.

(2) The desired standing wave resonance mode determined from the width, depth, and height of the heating chamber can be easily obtained even if the mounting plate is made of metal.

(3) Generally, the mounting plate is made of a special resin, which is expensive, but this is no longer necessary, making it more economical.

(4) Since it has become possible to construct mounting plates using metal without affecting the resonance mode of standing waves, conventional mounting plates made of resin can cause thermal deformation, melting, or even fire. As a result, a more reliable and safe high-frequency heating device can be provided.

[Brief explanation of the drawing]

Figures 1 and 2 are a side sectional view and a front sectional view of the main parts of a conventional high-frequency heating device, Figure 3 is an external perspective view of the mounting plate of the same device, and Figures 4 and 5 are resonances inside the heating chamber. 6 and 7 are side sectional views and front sectional views of essential parts of the high-frequency heating device of the present invention, and FIG. 8 is an external perspective view of the mounting plate of the same device. 1... Heating chamber, 2... Magnetron (high frequency oscillator), 5... Partition plate, 7... Upper wall surface, 9... Mounting plate, l ₁ ... Height of the vertical part of the mounting plate.

Claims (1)

[Scope of Claims] 1. A heating chamber that houses an object to be heated and has a substantially rectangular parallelepiped shape, and a high-frequency oscillator that is located approximately at the center of the upper wall of the heating chamber and that supplies high-frequency power into the heating chamber via an antenna. and a partition plate that protects the antenna portion of the high frequency oscillator, and a mounting plate that supports the partition plate on both sides, and the mounting plate includes a vertical plate having a height of 1/6 or less of the wavelength of the high frequency wave. The high frequency heating device is configured such that the vertical portion of the mounting plate is located at the peak of the standing wave. 2. The high-frequency heating device according to claim 1, wherein the mounting plate is made of a metallic sheet metal, and the vertical portion thereof is bent.