JPS6241386B2 - - Google Patents

Description

Detailed Description of the Invention The present invention aims to improve the heating distribution performance of a high frequency heating device, and in particular, improves the heating distribution performance by increasing the rotation effect of the antenna of a high frequency heating device using a rotating antenna. The purpose is to

Conventionally used rotating antennas are generally L-shaped with vertical and horizontal components, but the most important point when designing a rotating antenna type high-frequency heating device is how to do so. The problem is how to radiate radio waves more efficiently than the horizontal component. In conventional high-frequency heating devices, the proportion of radio wave radiation from the vertical component inevitably increases, and therefore the antenna rotation effect cannot be sufficiently obtained.

Although it is possible to increase the radio wave radiation from the horizontal component of the antenna by adjusting the length dimensions of the vertical and horizontal parts, it is possible to increase the radio wave radiation from the horizontal part of the total amount of radio wave radiation from the antenna. In order to increase the height, it is necessary to keep the length of the vertical component inside the heating chamber as small as possible. However, as the length of the vertical component of the antenna decreases, the distance between the horizontal component and the heating chamber wall also decreases, which increases the effectiveness of the well-known strip transmission line between them, making it difficult for radio waves to be radiated from the horizontal component.

Therefore, in the present invention, the wall surface of the heating chamber in the antenna coupling part is shaped so as to partially protrude toward the heating chamber side end surface of the vertical part of the antenna. Even if the actual effective length of the antenna is reduced, the distance between the horizontal component and the wall of the heating chamber is set to a distance that allows the radio waves from the horizontal component to be radiated more efficiently. , which aims to increase the rotational efficiency of the antenna and improve the heating distribution performance.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a main body, and a heating chamber 2 is located inside. The front opening of the heating chamber can be opened and closed by a door 3. 3 is a high frequency oscillator,
The radio waves oscillated by the high frequency oscillator are transmitted through the waveguide 4 and then radiated into the heating chamber by the rotating antenna 5. Rotating antenna has horizontal component 6
and the vertical component 7, and 8 is the rotational drive axis of the antenna made of dielectric material, and the vertical component 7 of the antenna is
It is connected to the. The rotational drive shaft 8 passes through a hole in the upper wall of the waveguide and is connected to the rotation shaft 10 of the drive motor 9 by a pin 11. 12 is a mounting plate for the motor 9.

Antenna coupling hole 14 on the heating chamber upper wall 13
The vicinity is located away from the waveguide side end face of the vertical component 7 of the antenna and close to the heating chamber side end face.
It has a structure that protrudes into the heating chamber. Therefore, although the effective length of the vertical component of the antenna within the heating chamber is very small, a sufficient distance is maintained between the horizontal component 6 and the upper wall 13 of the heating chamber.

As a result, by appropriately adjusting the length of the horizontal component 6, there is almost no radio wave radiation from the vertical component, and most of the radio wave radiation is performed more efficiently than the horizontal component, thus reducing the rotation effect of the antenna. The heat distribution is sufficiently increased, and good heating distribution characteristics can be obtained. At the same time, the distance between the inner end face of the waveguide in the vertical part of the antenna and the end face of the coupling hole 14 in the heating chamber and its surroundings increases, so sparks are likely to occur between these areas during operations with high standing waves, such as during light loads. However, that problem is also much less likely to occur. This effect is especially true when the height of the waveguide is kept to a minimum due to restrictions on the overall height of the product, but it is possible to secure a larger waveguide height just around the rotating antenna, making it difficult for sparks to occur. It is very important because it can be used in the structure. Furthermore, the orientation of the conventional waveguide, i.e. the rotating antenna and the coupling hole 14 of the heating chamber.
Due to the direction in which radio waves are transmitted, heating imbalances occur within the heating chamber, such as between the left and right sides, and between the front and rear. It has been experimentally confirmed that this heating imbalance can be resolved by making the surface protrude. This is considered to be because by providing the protrusion, the space between the protrusions becomes a coaxial line, and direct radio wave radiation from the coupling hole 14 is eliminated.

The protrusion is concentric with the central axis of rotation of the rotating antenna, but if its diameter is too small, a large radio wave loss will occur between the antenna and the protrusion on the heating chamber wall, and these parts will be Because it gets hot,
In this embodiment, the diameter of the base of the protrusion is made as large as possible, and the diameter gradually decreases toward the tip of the protrusion, so that it has a substantially truncated conical shape.
In this way, the radio wave loss between the protrusion and the antenna will be extremely small, and the heating distribution will be improved due to efficient radio wave radiation from the horizontal part of the antenna, as well as the tip of the vertical part of the antenna. This high-frequency heating device has extremely excellent performance, with the effect of preventing sparks between the walls of the heating chamber, as well as the effect of suppressing direct radio wave radiation from the coupling holes and preventing unbalanced heating due to the propagation direction of radio waves. can be provided.

If the aim is to suppress radio wave radiation from the vertical part of the rotating antenna and increase radio wave radiation from the horizontal part, the antenna itself may be shaped as shown in Figure 3, but in that case, ,
The effect of preventing sparks and the effect of preventing heating imbalance from side to side, front to back, etc. as described above cannot be obtained. 1
Reference numeral 5 denotes a sealing plate which seals the coupling hole 14 and serves as a bearing for the rotating antenna, and is made of a dielectric material.

As explained above, according to the present invention, radio waves can be radiated more efficiently than the horizontal component of the antenna, so that the rotation effect of the antenna can be enhanced and the heating distribution performance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a microwave oven showing an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the same main part, and FIG. 3 is a cross-sectional view showing a conventional example of the same part. 2... Heating chamber, 3... High frequency oscillator, 4... Waveguide, 5... Rotating antenna, 6... Horizontal component of antenna, 7... Vertical component of antenna, 14... Coupling hole.

Claims (1)

[Scope of Claims] 1. A heating chamber that accommodates an object to be heated, a high-frequency oscillator that supplies high-frequency energy to this heating chamber, and a waveguide that transmits radio waves oscillated by this high-frequency oscillator to the heating chamber. A rotating antenna is provided for coupling the waveguide and the heating chamber at high frequency, and the heating chamber wall surface at the coupling portion of the heating chamber and the rotating antenna is the tip of the vertical portion of the rotating antenna located within the waveguide. A high-frequency heating device configured to protrude into the heating chamber so as to move away from the vertical portion and approach the tip of the vertical portion located inside the heating chamber. 2. The high-frequency heating device according to claim 1, wherein the protruding portion of the heating chamber wall surface at the joint portion has a substantially truncated conical shape.