JPH0797516B2 - High frequency heating device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electromagnetic cooker using high frequency induction heating.

2. Description of the Related Art A conventional electromagnetic cooker using high-frequency induction heating is provided just above the exciting coil 24, which is a disk-shaped exciting coil 24 wound flatly as shown in FIG. The mounting plate 25 is made of ceramics or a heat-resistant glass plate for mounting the object 7 to be heated, and the high frequency inverter circuit 2 for supplying high frequency power to the excitation file 24.
Since this type of electromagnetic cooker does not use a fire, it does not generate extra heat in the summer and has a feature that conventional gas stoves and electric stoves do not have a risk of fire.

Problems to be Solved by the Invention However, even if such high safety is realized, for example, when boiling water is tried to be boiled in a kettle, the amount of water to be boiled or the boiling time depends on the water temperature. Since it is different, it has to be monitored in some form until the time of boiling up, and there is an inconvenience that the safety cannot be fully utilized for convenience.

In addition, in the high frequency inverter circuit 2 used in this type of electromagnetic cooker, not only the high frequency of 20 to 30 kHz, which is the basic frequency of the high frequency inverter circuit 2, but also electromagnetic wave noise including its high frequency component is radiated from the exciting coil 24 to the outside. There was a problem that it interfered with the surrounding electronic devices.

The present invention solves the above-mentioned conventional problems, and an object thereof is to automate heating and cooking, and to reduce the emission of electromagnetic noise to the outside.

Means for Solving the Problems In order to solve the above problems, the high-frequency heating device of the present invention includes a heating chamber formed of a metal wall that houses an exciting coil and an object to be heated, a heating chamber or a heating chamber and a vent hole. Detection means for detecting changes in temperature, humidity, or gas components such as CO in the atmosphere of the heating chamber caused by heating of the object to be heated in the space connected through the high-frequency inverter circuit Is provided with a control circuit for controlling the output of.

Effect The present invention has the above-described configuration, and gas components such as hot air, water vapor, or CO generated by the heating of the object to be heated are temporarily confined in the heating chamber and do not diffuse to the outside. It shows a very high correlation with the change of the object to be heated. By detecting this change by the detection means and performing the calculation and the determination operation preset on the detection output to control the high frequency inverter circuit, the heating can be automatically controlled according to the object to be heated.

Further, since the exciting coil is located in the heating chamber made of a metal wall, leakage of electromagnetic waves from the exciting coil, which has been inevitable in the past, can be greatly reduced.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a circuit diagram showing the basic configuration of the circuit. In FIG. 1, the high frequency power generated by the high frequency inverter circuit 2 is applied to the exciting coil unit 1. The exciting coil unit 1 is immediately below a ceramic partitioning plate 9 arranged near the bottom of a heating chamber 8 made of a metal wall, and generates a high frequency magnetic field by the applied high frequency power. Here, the exciting coil unit 1 has a winding 1a wound flatly in a disk shape, a plurality of ferrite cores 1c radially arranged below the winding 1a, and the windings described above, as shown in the cross section in FIG. 1a and a support 1b made of a dielectric material for supporting a ferrite core 1c. The object to be heated 7 placed on the partition plate 9 generates Joule heat generated by the dielectric current induced by the high-frequency magnetic field to generate heat, and heats the food (not shown) therein. Through a vent hole 22 formed by a punching hole provided in a part of the metal wall of the heating chamber 8, the inside of the heating chamber 8 and the inside of the exhaust guide 10 in a ventilating state detect the change of humidity in the heating chamber 8. A humidity detecting element 5 as a detecting means is provided. The door 18 is provided at the front opening of the heating chamber 8 so as to be openable and closable, and the switch means 6 is a second detection means for detecting the open / closed state of the door 18.
(Not shown in FIG. 1 and described as a functional block only in FIG. 2) is provided at the periphery of the front opening of the heating chamber 8. The control circuit 4 of the high frequency inverter circuit 2 is the first
The output of the high frequency inverter circuit 2 is controlled by the signals of the humidity detecting element 5 which is the detecting means and the switch means 6 which is the second detecting means.

In the above configuration, the object to be heated 7, which is a metal container such as a pan, generates an induced current due to the high frequency magnetic field generated in the exciting coil unit 1 and self-heats. On the other hand, although the exciting coil unit 1 is arranged near the bottom of the heating chamber 8 made of a metal wall surface, the ferrite core 1c is provided below the winding 1a.
Since a large number of radiating elements are radially provided, most of the high-frequency excitation is blocked by the ferrite core 1c and does not reach the metal wall of the heating chamber 8, so that the wall surface of the heating chamber 8 hardly generates heat. As a result, the food stored in the object to be heated 7 is heated, and steam is generated as the heating progresses. At this time, unlike the conventional electromagnetic cooker, in the case of the present embodiment, since the object to be heated 7 is surrounded by the heating chamber 8, the generated steam is once confined in the heating chamber 8, so that The humidity has a high correlation with the amount of water vapor generated from the food in the article to be heated 7. Therefore, the control circuit 4 judges the finished state of the food by the detection signal of the humidity detecting element 5 which detects the change of the humidity in the heating chamber 8 and controls the output of the high frequency inverter circuit 2 to automatically perform the optimum heating. An electromagnetic cooker that performs is realized. A control / determination method for this kind of automation is described in, for example, Japanese Patent Publication No. 60-5456.
The method described in Japanese Patent No. 1 can be specifically considered.

The switch means 6 is for detecting the open / closed state of the door 18 of the heating chamber 8. When the door 18 of the heating chamber 8 is opened, or when the door 18 is opened in the middle of heating, of course, heating is performed. Since the humidity in the chamber 8 is affected, the sequence corresponding to each case is determined by applying the output signal of the switch means 6 to the control circuit 4 in addition to the signal of the humidity detecting element 5. .

Further, in the case of the conventional electromagnetic cooker, the one that covers the exciting coil is basically one that transmits electromagnetic waves such as a dielectric or magnetic material, whereas in the case of the configuration of the present invention, the exciting coil unit 1 is made of a metal wall. Since it is arranged in the heating chamber 8, it is possible to prevent external leakage of interfering electromagnetic waves including the fundamental frequency of several tens kHz used for induction heating and the frequency that cannot be avoided in the past. It is possible.

Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a sectional view thereof, and FIG. 5 is a circuit diagram showing a basic configuration of the circuit. The difference from the above embodiment is that the high frequency power generated by the high frequency inverter circuit 2 can be applied to the power supply circuit for driving the magnetron 11 that generates microwaves by switching with the changeover switches 19a and 19b. The microwave is radiated into the heating chamber 8 through the waveguide 15 and the rotating antenna 16. Here, the power supply circuit (not shown in FIG. 4) of the magnetron 11 is composed of a step-up transformer 12, a high-voltage capacitor 13 and a diode 14, and the rotary antenna 16 is a motor.
It is rotated by 17. The switch 20 plays a role of a latch switch which automatically stops the operation when the door 18 is opened while driving the magnetron 11 in conjunction with opening and closing of the door 18. Excitation coil unit
23 is covered with a radio wave blocking cover made of a metal material such as an aluminum honeycomb in order to avoid damage such as heating and discharge due to the microwave generated in the magnetron 11. According to this configuration, since the heating chamber 8 is made of a metal wall, it can be used as a cavity for microwave heating, so that both induction heating by microwaves and induction heating by high frequency magnetic fields can be performed. Since the device can be realized and the humidity detecting insulator 5 can be used as a signal source for automation of heating control even in the case of dielectric heating by microwaves, the heating time control of microwave heating can be automated.

Effects of the Invention As described above, the high-frequency heating device of the present invention has the following effects.

(1) Since the exciting coil unit and the object to be heated are housed in a heating chamber made of a metal wall, it is possible to prevent leakage of interfering electromagnetic waves from the exciting coil, which cannot be avoided in the past.

(2) Hot air, water vapor, or gas components such as CO generated when the object to be heated is trapped in the heating chamber,
Since it does not diffuse directly to the outside, heating control can be automated by detecting this change in atmosphere.

(3) Since the signal of the switch means for detecting the opening / closing of the door is used as the input of the control circuit, it is possible to set the optimum control sequence in which the open / close state of the door is set as a condition.

(4) In the exciting coil unit, since the ferrite cores are radially arranged under the winding, despite the fact that the exciting coil unit is provided near the bottom of the heating chamber on the metal wall surface,
There is almost no loss due to the induced current on the metal wall surface, and an efficient electromagnetic cooker is realized.

(5) Storing the exciting coil and the object to be heated in a heating chamber made of a metal wall not only prevents the oil from splashing when performing roofing, but also allows automatic detection at the time of ignition and optimal control for it. It is something to do.

[Brief description of drawings]

FIG. 1 is a sectional view of a high frequency heating apparatus according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram showing the basic configuration of the circuit.
FIG. 3 is a sectional view of the exciting coil unit portion of the above embodiment,
FIG. 4 is a sectional view of the high frequency heating apparatus according to the second embodiment of the present invention, FIG. 5 is a circuit diagram showing the basic configuration of the circuit, and FIG. 6 is a sectional view of a conventional high frequency heating apparatus. 1 ... Excitation coil unit, 2 ... High frequency inverter circuit, 4 ... Control circuit, 5 ... Humidity detection element, 6 ... Switch means, 7 ... Heated object, 8 ... Heating chamber, 9 ... Support Cutting board, 10 ... Exhaust guide, 11 ... Magnetron, 18 ... Door.

Claims (2)

[Claims] Claim: What is claimed is: 1. An exciting coil, which is formed by winding a winding wire into a flat shape and has a disk shape, a ferrite core provided below the exciting coil, a high frequency inverter circuit for supplying electric power to the exciting core, and an openable and closable circuit. A door, a heating chamber made of a metal wall that houses the exciting coil and the object to be heated, and the heating chamber or a space connected to the heating chamber through a ventilation hole A high-frequency heating device comprising: a detection unit that detects a change in the temperature, humidity, or a gas component of the atmosphere in the heating chamber that occurs, and a control circuit that controls the output of the high-frequency inverter circuit by the detection signal of the detection unit. 2. A magnetron for generating microwaves for irradiating a heating chamber, and a step-up transformer of the magnetron which is operated by receiving supply of electric power from the high frequency inverter circuit. High frequency heating device.