JPS6236353B2 - - Google Patents

Description

[Detailed description of the invention] A sensor is provided to detect the state inside the heating chamber, and the heating state of the object to be heated is measured based on the output of this sensor, and the oscillation state of the magnetron or the operation of the heater is controlled via the control circuit. do. High-frequency heating devices configured to perform so-called automatic heating have been put into practical use. This eliminates the need to set the heating time each time, making it easy to use.Moreover, by changing the heating conditions according to the quality of the object to be heated and performing the most appropriate heating, it is possible to improve the finished product.

The present invention relates to a high-frequency heating device equipped with such an automatic device, and aims to realize a high-frequency heating device with excellent heating performance by making the operation of the sensor more reliable and making the finished state of the heated object more stable. It is something.

FIG. 1 is a perspective view showing the appearance of a high-frequency heating device according to the present invention. In FIG. 1, a door 2 is provided on the front surface of a main body 1 so as to be openable and closable. Reference numeral 3 denotes an operation panel, which includes a display section 4 and a keypad 5.

FIG. 2 is a sectional view showing the structure of the high frequency heating device according to the present invention. In FIG. 2, a magnetron 8 is provided in the heating chamber 6 via a waveguide 7, and radio waves are irradiated into the heating chamber 6. 9 is a fan motor that cools the magnetron 8. The cooling air from the fan motor 9 enters the heating chamber 6 through an air intake port 10 provided in the heating chamber 6, as shown by a solid arrow, and is discharged to the outside through an exhaust port 11 through a guide 12. 13 is a sensor that detects the state of gas such as the concentration of gas such as alcohol gas in the heating chamber 6, and the gas sensing part 16 is arranged in the guide 12 near the exhaust port 11 to It is set up in
When the object to be heated 14 is high-frequency heated by radio waves from the magnetron 8, gases are generated depending on the object to be heated, such as alcohol gas being generated when the object to be heated 14 is alcoholic beverages, for example. This gas moves within the heating chamber 6 along with the cooling air as shown by the broken line arrow, and is discharged from the exhaust port 11. This gas increases the gas concentration in the heating chamber 6, and by detecting the change in gas concentration, the heated object 14 can be indirectly heated.
You can know the heating status of the 15 is a heater for browning the object to be heated 14;

FIG. 3 is a circuit diagram of a high frequency heating device according to the present invention. In FIG. 3, a power fuse 16, a door switch 17 that moves to open and close the door 2, a changeover switch 18 that switches between high frequency heating and electric heating to the heater 15, and a relay A19 that opens and closes the main circuit are connected to a high voltage transformer 20 through contacts. do. The high voltage transformer 20 has a capacitor 21 and a diode 22.
Connect to magnetron 8 via. 23 is a control board to which power is supplied by a low voltage transformer 24. A microcomputer 25 is provided on the control board 23 and connected to the keyboard 5 via a converter 26. The converter 26 converts the signal from the keyboard 5 into a signal for the microcomputer 25. The microcomputer 25 displays the contents of this signal on the display section 4. sensor 1
3. Detects the gas concentration of the gas in the heating chamber 6 and transmits it to the microcomputer 25 as an electrical signal. 2
7 is a relay B for opening and closing the fan motor 9, which is connected to the microcomputer 25 together with the relay A 19 via a converter 28, and is energized by this output signal to open and close each relay coil.

The signal contents of the keyboard 5 and the sensor 13 are processed according to a program stored in advance in the microcomputer 25, and the output contents are sent to the relay A16 and relay B27 via the converter 28.
Open and close.

FIG. 4 is a characteristic diagram showing the operating state of the high frequency heating device according to the present invention.

In FIG. 4, the vertical axis represents the gas concentration in the heating chamber 6 detected by the sensor 13, and the horizontal axis represents the elapsed time after the start of operation of the apparatus. A solid arrow indicates a change in the gas concentration in the heating chamber 6 after the operation is started from a state A where the gas concentration in the heating chamber 6 is relatively high, such as after continuous use. The difference from the set gas concentration S stored in the microcomputer 25 is calculated, and at the same time as the start of operation, the relay B27 is closed to operate the fan motor 9. A preliminary operation is performed in which the heating chamber 6 is ventilated by the fan motor 9 to reduce the gas concentration within the heating chamber 6. The gas concentration decreases, the sensor 13 detects the gas concentration, and the microcomputer 25 sets the set gas concentration S.
At point D, when it is detected that the temperature has reached , the relay A19 is closed, the high-voltage transformer 20 is energized, the magnetron 8 is oscillated, and high-frequency heating is started.

When the object to be heated 14 is heated by high-frequency heating, a gas corresponding to the type of object to be heated is generated, such as alcohol gas if the object to be heated 14 is alcoholic beverages, and gradually the gas in the heating chamber 6 is generated. concentration increases. As soon as the object to be heated 14 boils and begins to brown, the amount of gas increases rapidly. If the gas is detected at point F where a preset amount of change △g1 is obtained, the heating state of the object to be heated 14 can be indirectly known, and the subsequent heating conditions can be determined according to the type of the object to be heated 14. , the microcomputer 25 automatically heats the heating time even if the user does not set the heating time. The one-dot chain line shows the characteristics when the operation is started from the state of gas concentration B, and the two-dot chain line shows the characteristics when the operation is started from the state of gas concentration C. In both cases, the amount of change from the gas concentration G at saturation △
Since g2 can be made sufficiently larger than the amount of change in gas concentration Δg1 required for gas detection, detection can be performed reliably in any initial gas concentration state. By setting the value of the set gas concentration S to a value lower than the gas concentration (A to C) in the heating chamber that can occur under normal conditions, the heating operation is performed after the gas concentration is always stabilized at a constant level through preliminary operation. Therefore, changes in gas concentration due to heating can be reliably detected. The broken line shows the gas concentration change when heating is started from state A of high gas concentration without performing the preliminary operation according to the present invention, that is, the gas concentration adjustment operation. According to this, the gas concentration gradually increases as the heating progresses from point A, and the gas concentration difference Δg3 from the gas concentration G at saturation becomes extremely small. In order to perform detection with this small gas concentration difference △g3, the sensitivity of the detection circuit must be increased, which not only makes the circuit complex, expensive, and uneconomical, but also makes it susceptible to noise. There is also a risk of malfunction. As described above, according to the circuit configuration according to the present invention, the gas concentration difference △g1 can be made large, so the sensitivity of the detection circuit can be low, the circuit can be easily constructed, and it is not only inexpensive and economical, but also free from the effects of noise. It is difficult to detect and can always detect gas accurately. Therefore, this means that the heating state of the object to be heated 14 can always be accurately detected, stable heating can be performed, and the most preferable heating result can be obtained depending on the object to be heated. This makes it possible to provide a high-frequency heating device with extremely high heating performance, which is the most important basic performance for a heating device. According to the present invention, since the amount of change in gas concentration is measured as the detected value, the amount of change in gas concentration can be determined by the fact that a large amount of gas is generated as the food is heated, and that it can be measured before and after boiling. Due to the nature of the gas amount changing drastically,
Compared to methods such as detecting changes in food temperature as changes in temperature in a heating chamber, gas detection can detect food completion more fully and accurately.

Since the gas concentration in the heating chamber as a whole is adjusted by operating the cooling fan motor, compared to methods that adjust the apparent relative humidity by increasing the temperature only near the sensor, the gas concentration in the heating chamber during heating operation is The correlation between the gas concentration and the detection output of the gas sensor section is improved, allowing more accurate detection.

In addition, even if the heating chamber has a high gas concentration and high temperature immediately after cooking, the cooling fan can operate to lower the gas concentration and lower the temperature inside the heating chamber, allowing continuous heating and cooking. You can also do

Since the magnetron starts operating after the gas concentration adjustment operation, even when heating lightweight foods, there is no problem such as steam being released during the gas concentration adjustment operation and the gas being unable to be detected during heating.

After the gas concentration adjustment operation, the circuit starts the heating operation, and the gas concentration adjustment operation is also configured so that the cooling fan motor discharges the gas in the heating chamber to the outside while the door is closed. The operator can use the device simply by placing the food to be heated into the heating chamber and starting heating, as in normal use, so there is no need for any troublesome operations and the device is easy to operate.

It goes without saying that the same effect can be obtained even when applied to automatic heating that detects the gas concentration during browning and heating when heating with a heater. It goes without saying that the same effect can be obtained even when applied to automatic heating that detects the gas concentration during browning and heating when heating with a heater.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the external appearance of a high-frequency heating device according to the present invention, Fig. 2 is a sectional view showing the structure of the device, Fig. 3 is a circuit diagram of the device, and Fig. 4 is an operating state of the device. FIG. 8... Magnetron, 9... Fan motor, 1
3...Sensor, 14...Heated object, 15...Heater.

Claims (1)

[Claims] 1 A magnetron that irradiates radio waves into the heating chamber and a cooling fan motor are installed, as well as a sensor that detects the gas concentration of the gas in the heating chamber, and when the gas concentration in the heating chamber at the start of operation is outside the set value, the cooling fan is Gas concentration adjustment operation is performed by operating a motor, etc. until the gas concentration in the heating chamber reaches the set value, and then heating operation is started and the operation of the magnetron or heater is controlled by changes in the output value of the sensor. A high-frequency heating device characterized by having a circuit configuration.