JPH0324755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to a high-frequency heating device that heats an object to be heated to a predetermined temperature by supplying a predetermined power to a heating coil.

(2) Prior art High-frequency heating equipment generally has the following features as shown in Figure 1:
Applying the output of the high frequency oscillator 1 to the heating coil 2,
The temperature of the heated body 3 heated by this heating coil 2 is measured with a radiation thermometer 4, and this radiation thermometer 4
Based on the measured temperature, the controller 5 adjusts the control voltage of the high frequency oscillator 1 so that the temperature of the heated object 3 becomes a predetermined value.
Eo was controlled and a predetermined power was supplied to the heating coil 2.

However, in order to heat a large number of objects 3 to be heated, it is necessary to prepare a plurality of high frequency oscillators 1, resulting in a problem that the device becomes very expensive.

Therefore, as shown in FIG. 2, if the capacity of the plurality of heating coils for heating the object to be heated is small, the power output of one high-frequency oscillator 1 is constant, and this is controlled by the plurality of rectifiers 6. After rectifying the
The oscillator 7 is driven, the output of the oscillator 7 is applied to the small-capacity heating coil 2, the temperature of the heated body 3 heated by the heating coil 2 is measured by the radiation thermometer 4, and the temperature of the heated body 3 is measured by the radiation thermometer 4. The control voltage of the oscillator 7 via
There is a method of controlling E ₁ and controlling the power of the heating coil 2.

However, even with this method, large rectifiers, oscillators, etc. are required, resulting in a complicated and expensive structure.

For this purpose, as shown in FIG. 3, a plurality of relatively small capacity movable iron core transformers 81 and 82 are connected to one high frequency oscillator 1 with a constant power output, and the heating coils 21 and 22 are heated by this output. Heated object 3
1 and 32 were measured by radiation thermometers 41 and 42, the iron cores of movable iron core transistors 81 and 82 were controlled, and the power of heating coils 21 and 22 was controlled.

However, this method is easy to configure and
Although it was cheaper, it had the disadvantage of poor responsiveness.

(3) Purpose of the Invention In view of the above points, the purpose of the present invention is to provide a high-frequency heating device that is inexpensive, has quick response, and can control the power of a plurality of heating coils connected to one high-frequency oscillator. It is.

(4) Embodiment of the Invention FIG. 4 is a configuration explanatory diagram showing an embodiment of the invention, and the same reference numerals as those in FIGS. 1 to 3 indicate the same components.

In the figure, 1 is one high frequency oscillator, and its output is sent to multiple transformers 9 via output line l.
1,92, for example 1000V to 100V
It is stepped down to ~500V. The outputs of the transformers 91 and 92 are separately applied to a plurality of thyristors 101 and 102, respectively.
As a result, the heating coils 21 and 22 are driven to perform high-frequency heating on the objects 31 and 32 to be heated. And heated body 3
Radiation thermometer 41,
Measured non-contact with 42, multiple controllers 51, 5
2 compares the outputs of the radiation thermometers 41 and 42 with a preset setting value and generates an adjustment signal. This adjustment signal causes multiple ignition circuits 11
1, 112 controls the thyristors 101, 102 by frequency dividing firing control to control the ON time t within a constant cycle base T as shown in FIG.
A predetermined power is supplied to the

That is, the output of one high frequency oscillator 1 is distributed and applied to the heating coils 21 and 22 via the plurality of thyristors 101 and 102 to
32 and measure its temperature with radiation thermometers 41 and 42, controllers 51 and 52, and ignition circuit 11.
1 and 112, the thyristors 101 and 102 are subjected to frequency division firing control to supply predetermined power to the heating coils 21 and 22.

Therefore, the device has advantages such as low cost and quick response.

In addition, in the above example, the control loop was explained as having two loops, but it is also possible to have more than two loops.
The transformers 91 and 92 are provided as needed and can be omitted.

(5) Summary of the Invention As described above, the present invention applies the output of one high-frequency oscillator to a heating coil via a plurality of thyristors, and controls the firing of the thyristors by frequency division using a firing circuit. This is a high-frequency heating device.

(6) Effects of the invention Therefore, compared to the conventional example, the device can be made significantly smaller, simpler, cheaper, and more reliable for controlling the power supplied to multiple heating coils. . In addition, since frequency-divided firing control is performed, it is highly efficient as it does not generate harmonics in the heating coil compared to phase angle control, and the response is fast and high-precision heating control is possible, which has practical effects. is extremely large.

[Brief explanation of drawings]

1, 2, and 3 are configuration explanatory diagrams showing a conventional example, FIG. 4 is a configuration explanatory diagram showing an embodiment of the present invention, and FIG. 5 is a waveform diagram for explaining operation. 1... High frequency oscillator, 21, 22... Heating coil, 101, 102... Thyristor, 111, 1
12...Ignition circuit.

Claims (1)

[Claims] 1. One high-frequency oscillator, a plurality of thyristors to which the output of this high-frequency oscillator is distributed and applied, a plurality of heating coils that are driven by these thyristors to high-frequency heat a heated object, and a surface temperature of the heated object. a plurality of radiation thermometers that each measure non-contact, a plurality of controllers that generate adjustment signals by comparing the output of each radiation thermometer with a set value, and an adjustment signal of each controller that controls the thyristor. 1. A high-frequency heating device characterized by comprising a plurality of ignition circuits that perform frequency division ignition control to control on-time within a certain period, and constantly heat a heated object to a predetermined temperature.