JPS5812717B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-frequency heating device for heating and cooking an object housed in a heating chamber while rotating the object.

Conventional structure and its problems Recently, in order to drive the rotary mounting table inside the heating chamber, the conventional rotary drive shaft that was installed through the bottom plate of the heating chamber was abolished, and the rotary mounting table was driven by magnetic coupling force. Rotation-driven high-frequency heating devices have been put into practical use and are attracting attention.

That is, this high-frequency heating device has a rotary mounting table rotatably provided on the inner bottom surface of the heating chamber, a rotary body provided on the outer bottom surface of the heating chamber, and a first magnet, Further, a second magnet is attached to the upper surface of the rotating body.

Then, the rotating body is driven to rotate, and the rotating mounting table is driven to rotate by the accompanying magnetic coupling force or repulsive force between the first magnet and the second magnet.

However, this high frequency heating device still has the following problems.

In other words, when the magnet attached to the rotating mounting table generates heat due to the microwaves emitted from the magnetron, the magnetic coupling force decreases. No influence《
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However, this method requires a separate component, the metal cover, and also involves work to fix the metal cover, resulting in an increase in cost.

In addition, in order to bring the first and second magnets close together to strengthen their attractive or repulsive force, this metal cover must be placed close to the bottom plate of the heating chamber, and as a result, the microwave During this time, a spark is generated,
This had the disadvantage that discharge marks remained on the bottom plate, reducing its commercial value.

Purpose of the Invention The present invention solves the above-mentioned conventional drawbacks, and aims to provide a high-frequency heating device that does not deteriorate the characteristics of the magnet even when the magnet is irradiated with microwaves and is inexpensive to produce. be.

Structure of the Invention In order to achieve the above object, the high frequency heating device of the present invention includes a heating chamber, a rotary mounting table rotatably provided on the inner bottom surface of the heating chamber, and a rotary mounting table provided opposite to the rotary mounting table on the inner bottom surface of the heating chamber. It has a rotating body that is rotatably provided on the outer bottom surface and a drive motor that rotationally drives the rotating body, and a first magnet is attached to the rotating mounting table, and a first magnet is attached to the rotating body. A second magnet is mounted facing the magnet, and the first magnet is made of ferrite with a resistivity of 105Ω1c or more, so even if the magnet is irradiated with high frequency, the heat generation temperature is low, so the magnet Since there is no need to cover the magnet with a metal cover, the number of parts and assembly work can be reduced, and the high-frequency heating device can be provided at a low cost.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a main body of a high-frequency heating device. A heating chamber 2 is provided inside the main body 1, and a door 3 is provided at the opening of the heating chamber 2 so as to be openable and closable.

On the other hand, the heating chamber 2 is formed into an upper chamber 2a by a top plate 4 made of a lossy dielectric material.
and a lower chamber 2b, of which an antenna 5a of a magnetron 5 and a stirrer fan 6 are provided in the upper chamber 2a.

Further, the lower chamber 2b is provided with a rotary mounting table 7 made of glass or a synthetic resin with low dielectric loss. It is rotatably supported on the inner bottom surface.

On the other hand, a rotary body 10 is rotatably provided on the outer bottom surface of the heating chamber 2, facing the rotary mounting table 7.

The rotating mounting table 7 and the rotating body 10 have a first
The second magnets 11, 12 are attached, and the magnets 11, 12
There is an attractive force between the two.

Therefore, when the rotating body 10 is rotationally driven by the drive motor 14 via the belt 13, the rotating mounting table 7 is also rotationally driven by this suction force.

In the above configuration, the first magnet 11 is made of ferrite having a resistivity of 105Ω1cn or more in order to prevent heat generation due to microwaves, and the second magnet 11 is made of ferrite having a resistivity of 105Ω1cn or more.
The basis for the composition of ferrite will be clarified through experiments.

First, the resistivity is 10-2, 10-1, 10°, 101,
102, 103, 104, 105, 106, 107 [Ω
A total of 50 magnets, 5 each made of 1 cm] ferrite, were prepared, and 5 of them having the same resistivity were placed in the heating chamber 2 in order.

Then, magnetron 5 with 600W output is connected to these magnets.
As a result of irradiation with microwaves of 2450 MHz for 1 minute, the temperature reached the value shown in Figure 2.

This experiment was conducted in a normal 15°C atmosphere, so the temperature increase was (-15°C) from the measured value.
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As is clear from Figure 2, those with a resistivity of up to 104 Ω 1 cm have a temperature of 100°C or higher, whereas those with a resistivity of 105 Ω 1 cm or more have a temperature of 80°C or lower. In particular, when the resistivity was 107 Ω-cm), there was almost no temperature rise.

The reason for this is thought to be that the surface current becomes large when the resistivity is up to 10 4 Ω-cm, whereas the surface current becomes small when the resistivity is 10 5 Ω-cm or more.

If the temperature is around 80 degrees Celsius, even if your hand touches this magnet, you will not get burned.Moreover, even the synthetic resin frame 8 and rollers 9 will soften and lose their shape at this temperature. Since no deviation occurs, the resistivity is 105 in this example.
The magnet 11 made of ferrite with an ohm-cm diameter was not covered with a metal cover, but was buried when the rotary mounting table 7 made of synthetic resin was molded.

Therefore, the metal cover that covers the magnet 11 as in the conventional case is not required, and the work of fixing the metal cover can also be eliminated, thereby making it possible to provide the magnet 11 at a low cost.

Also, as a result of the abolishment of the metal cover, sparks are generated between the metal cover and the bottom plate of the heating chamber, unlike in the past.
It is also possible to prevent discharge marks from remaining on the bottom plate and reducing the product value.

Effects of the Invention As described above, according to the high-frequency heating device of the present invention, the first magnet provided on the rotary mounting table is made of ferrite having a resistivity of 105Ω1cm or more. Since the heat generation temperature is low, there is no need to provide a metal cover to protect the magnet, and it is convenient to embed it in a rotating resin mounting table, which can reduce production costs.

Further, by eliminating the metal cover, there is no spark generated between the bottom plate of the heating chamber and the metal cover, which has the effect of preventing a decrease in product value.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a high-frequency heating device according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing the temperature rise of the first magnet. 2... Gaya chamber, 7... Rotating mounting table, 10
...Rotating body, 11...First magnet, 1
2... Second magnet, 14... Drive motor.

Claims (1)

[Scope of Claims] 1. A heating chamber, a rotating mounting table rotatably provided on the inner bottom surface of the heating chamber, and a rotary mounting table rotatably provided on the outer bottom surface of the heating chamber opposite to the rotating mounting table. and a drive motor for rotationally driving the rotating body, a first magnet is attached to the rotating mounting table, and a second magnet is attached to the rotating body opposite to the first magnet. The first magnet is a high-frequency heating device made of ferrite with a resistivity of 105-(m or more). The high-frequency heating device according to claim 1, which is embedded in a rotating mounting table.