JPH0550834B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device for cooking food using high-frequency waves.

2. Description of the Related Art A high-frequency heating device has been developed as a method for supplying high-frequency waves into a heating chamber in which food is stored, in which a power supply port is provided on the top or side wall of the heating chamber.

A conventional high-frequency heating device in which a power supply port is provided on the side wall of the heating chamber will be explained with reference to FIG.
A power supply port 25 is provided on the side wall surface 24 of 3, and a waveguide 26 is provided.
The high frequency waves generated by the magnetron 27 are fed into the heating chamber 23 via the magnetron 27 . Further, at the inner bottom of the heating chamber 23, a turntable 30, on which the object to be heated 28 is placed, is rotatably driven by a motor 29 provided outside the heating chamber 23.

Problems to be Solved by the Invention However, such high frequency heating devices have the following problems.

(1) When the power supply port is located at the top of the side wall 24 of the heating chamber 23 or on the ceiling, the upper part of the object that is relatively tall, such as a milk bottle, is most likely to be heated, resulting in uneven heating ( (Temperature difference between top and bottom), making it difficult to use.

(2) Generally, the distance from the food placement surface of the turntable 30 to the bottom surface of the heating chamber 23 is very small compared to the distance from the food placement surface of the turntable 30 to the top surface of the heating chamber 23. If a power supply port is provided on the top or side wall surface of the turntable 30, the electric field under the turntable 30 tends to become weaker, and uneven heating tends to occur particularly at the center of the bottom surface of the object to be heated. For this reason, a method of increasing the distance between the food placement surface of the turntable and the bottom of the heating chamber could be considered, but this would increase the level difference between the turntable and the lower end of the front opening of the heating chamber, making it difficult to use when loading and unloading the heated items. There was a drawback that it became worse.

(3) If the power supply port 25 is located relatively far away from the object to be heated 28 in the heating chamber 23, for example at the top of the side wall 24, the radio waves emitted from the power supply port 25 will be reflected by the wall surface of the heating chamber 23. Then heated object 2
8 increases, the high frequency loss occurring on the wall surface of the heating chamber 23 cannot be ignored, and the heating efficiency also decreases.

The present invention solves these conventional problems, and aims to provide a high-frequency heating device that has a simple configuration, has excellent uniform heating properties, and is easy to use.

Means for Solving the Problems The high frequency heating device of the present invention reduces the height difference between the food placement surface of the turntable and the front opening of the heating chamber by 1/4.
λ or less, and the center of the power supply port provided on the side wall surface of the heating chamber is located within a range of 3/4λ of the high frequency wavelength from the food placement surface of the turntable.

Effect The high-frequency heating device of the present invention has the center of the power supply port within a range of 3/4λ from the food placement surface of the turntable, so that the center position of the power supply port is directly horizontal to the general object to be heated. Alternatively, since it is located diagonally downward, it becomes easy to uniformly heat milk bottles, etc., which tend to be heated unevenly in the upper and lower portions. In addition, since the radio waves can more easily reach the lower side of the turntable, it becomes easier to heat the bottom of the object to be heated, and uniform heating properties are further improved.

Furthermore, by locating the power supply port on the side wall surface of the heating chamber close to the object to be heated, even a small amount of object to be heated can be directly irradiated with radio waves, increasing the heating efficiency.

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

As shown in FIGS. 1 to 3, a turntable 4 on which an object to be heated 2 is placed and rotated by a motor 3 is provided at the inner bottom of the heating chamber 1. Power supply port 6 that radiates high frequency into heating chamber 1
is installed. The high frequency waves generated by the magnetron 7 are supplied from a magnetron antenna 8 through a waveguide 9 into the heating chamber 1 through a power feed port 6. The power supply port 6 is covered from the inside of the heating chamber 1 with a partition plate 10 made of a low dielectric material.

Further, a door 11 that can be opened and closed is provided at the front opening of the heating chamber 1, and a control section 12 is provided at the front of the main body of the apparatus.

By setting the step l ₁ between the food placement surface (X-X') of the turntable 4 and the lower end of the front opening of the heating chamber 1 to be less than 1/4λ of the high frequency wavelength (approximately 30 mm or less at 2450MHz), the heating chamber There is no problem in usability when the heated object 2 is put in and taken out of the heated object 1.

On the other hand, the food placement surface of the turntable 4 (X-
Dimension from X') to the center of the power supply port 6 (point A) l ₂
As is clear from the experimental results of the temperature difference between the above (point A) and the milk bottle (height approx. 140 mm) shown in Figure 4, by setting it within the range of 3/4λ, the temperature of the milk bottle, etc. There is no problem in actual cooking performance even with tall objects to be heated. In addition, the above configuration makes it easier for radio waves to reach the bottom of the turntable, eliminating uneven heating at the center of the bottom of the heated object, which was a problem in the past, and supplying power to general heated objects. Since the position of the port 6 is closer to the object to be heated in the side wall surface 5, the power supply port 6
The rate at which the radio waves emitted from the heat source are directly irradiated onto the heated object increases, improving heating efficiency.

In the embodiments shown in FIGS. 1 to 3, point A, the center of the power feed port, and point B (power supply point), which bisects the waveguide 9 by a perpendicular line drawn in the axial direction of the magnetron antenna 8, are , are arranged at the same height, but other embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows a high frequency heating device according to another embodiment of the present invention. In FIG. 5, a turntable 16 on which an object to be heated 14 is placed and rotated by a motor 15 is provided at the inner bottom of the heating chamber 13, and a power supply port 18 for irradiating high frequency waves is provided on the side wall surface 17 of the heating chamber 13. is installed. magnetron 1
The high frequency generated at 9 is transmitted to magnetron antenna 2.
0 into the heating chamber 13 from the power supply port 18 via the waveguide 21. The power supply port 18 is covered with a partition plate 22 made of a low dielectric material.

Food placement surface of turntable 16 and heating chamber 13
The vertical difference from the lower end of the front opening (not shown) and the positional relationship between the turntable 16 and the center of the power feed port 18 (point A) are the same as the range shown in FIGS. 1 to 3. However, point B, which bisects the waveguide 21 by a perpendicular line drawn in the axial direction of the magnetron antenna 20, is located at a higher position than point A.

In the high frequency heating device configured as above,
Since point B is located at a higher position than the center of the power supply port (point A), the radio waves supplied from the power supply port 18 into the heating chamber 13 tend to exhibit directivity in the traveling direction within the waveguide 18. Therefore, as is clear from the experimental results shown in FIG. 6, by placing point B higher than the center of the power supply port 18 (point A), it is possible to heat a tall object such as a milk bottle. This has the effect of further eliminating heating unevenness.

Furthermore, the density of radio waves at the bottom of the turntable 16 can be easily increased, and uneven heating at the center of the bottom of the object to be heated can be eliminated, making it possible to provide a high-frequency heating device that is easy to use and has fewer cooking failures.

Effects of the Invention As described above, the high-frequency heating device of the present invention has a power feeding port on the side wall of the heating chamber, and the dimension from the food placement surface of the turntable to the lower part of the front opening of the heating chamber is set to 1/4λ of the high-frequency wavelength. In addition to providing within the scope of
The center of the power supply port is located within a height of 3/4λ or less from the food placement surface of the turntable, and has the following effects, reducing cooking failures and providing easy-to-use high-frequency power. A heating device can be provided.

(1) The height difference from the food placement surface of the turntable to the center of the power supply port is less than 3/4λ, which prevents uneven heating (temperature difference between the top and bottom) even for relatively tall objects such as milk bottles. is less likely to occur.

(2) The level difference between the food placement surface of the turntable and the lower end of the front opening of the heating chamber is 1/2 so that it does not hinder usability.
4λ, but since the power supply port is located relatively lower on the side wall surface of the heating chamber, the radio wave density at the bottom of the turntable is also increased, and the bottom of the object to be heated is It also eliminates uneven heating that tends to occur in the center.

(3) When heating a general object to be heated, the power feed port is located close to the object to be heated, so the ratio of direct irradiation of radio waves from the power feed port increases, improving heating efficiency.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a high-frequency heating device according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the same main part, Fig. 3 is an external perspective view of the same, and Fig. 4 is a power supply port of the same high-frequency heating device. A characteristic diagram showing the center position (in the vertical direction) and the vertical temperature difference of heating by a milk bottle, FIG. 5 is a longitudinal cross-sectional view of a high-frequency heating device in another embodiment of the present invention, and FIG. 6 is a diagram showing the same high-frequency heating device. FIG. 7 is a characteristic diagram showing heating characteristics in relation to the power feeding point and the center position of the power feeding port, and FIG. 7 is a longitudinal cross-sectional view showing a conventional high-frequency heating device. 1... Heating chamber, 2... Heated object, 4... Turntable, 6... Power supply port, 7... Magnetron,
8... Magnetron antenna, 9... Waveguide.

Claims (1)

[Scope of Claims] 1. A heating chamber for storing food, a power supply port provided on a side wall of the heating chamber, a magnetron that generates high frequency waves, and a waveguide that guides the high frequency waves generated by the magnetron to the power supply port. and a turntable that is provided at the bottom of the heating chamber and rotates with food placed thereon, and the vertical difference between the food placement surface of the turntable and the lower end of the front opening of the heating chamber is defined by a high frequency wavelength as λ. 1/4λ, and the center of the power supply port is located within a height of 3/4λ or less from the food placement surface of the turntable. 2. The high-frequency heating device according to claim 1, wherein the point bisecting the waveguide by a perpendicular line drawn in the axial direction of the magnetron antenna is provided above the center point of the power feeding port.