JPS62291892A - Heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Industrial Field of Application The present invention provides a composite heating device equipped with a heater and microwave heating means, in which when an object to be heated ignites and burns,
The invention relates to a safety control system that detects this and stops the operation of the heating device.

The conventional high-frequency heating device described in Japanese Patent Application Publication No. 1885/1985 is equipped with a temperature switch at the exhaust port for forced ventilation in the heating chamber, and uses this temperature switch to detect an abnormal temperature rise in the heating chamber. A safety device is disclosed that quickly stops high-frequency oscillation even if a prize ignites and burns in a heating chamber.

According to this, even if the temperature of the food in the heating chamber rises abnormally due to a malfunction or setting error in the timer, leading to ignition, twisting, or baking, the temperature switch installed at the exhaust port will quickly detect this. By stopping the operation of the blower and magnetron, it is possible to prevent flames from blowing out of the exhaust port and causing flames to spread to curtains and wall materials near the exhaust port.

Safety devices similar to this are widely used in household high-frequency heating devices such as microwave ovens.

Problems that the invention aims to solveHowever, in recent years, as complex heating devices such as oven microwave ovens that incorporate electric heaters and gas burners have appeared on the market, the above-mentioned safety devices have been forced to be reconsidered. I can no longer use it.

In other words, in such a composite heating device, the temperature inside the heating chamber reaches a maximum of 250 to 300'C even in normal use.
Naturally, conventional temperature switches are also exposed to high temperatures of around 200°C. And since this is normal oven operation, the temperature switch should not operate and cut off power to the heating device. Therefore, the operating temperature of the temperature switch is the maximum temperature at which the oven operates, plus an additional margin, and when the food inevitably ignites and burns, it cannot be detected quickly and it may take a considerable time after the ignition. The temperature switch finally worked, and it no longer functioned as a safety device.

To give an example, the operating temperature of a combustion detection temperature switch in a conventional microwave oven is about 120° C., and it operates within 1 to 2 minutes after ignition. However, in a microwave oven, the operating temperature of this temperature switch is 230°C.
It finally started working 10 to 15 minutes after ignition.

At this time, the dish towel-like cloth placed over the exhaust vent caught fire.

The present invention solves these conventional problems and realizes a safety control system that quickly detects ignition and combustion of food in the heating chamber and stops the operation of the heating device even in a complex heating device. It is something.

Means for Solving the Problems The heating device of the present invention is equipped with a temperature sensor that detects the temperature inside the heating chamber, and the control section has counter means and storage means. Control the power supply to the means.

Function: The control unit of the heating device of the present invention counts a certain amount of time from the start of heating using the counter means, and suspends the determination and processing of ignition/combustion detection by the temperature sensor until this time elapses. After the combustion detection temperature stored in the storage means is compared with the temperature inside the heating chamber detected by the temperature sensor, and when the detected value of the temperature sensor is equal to or exceeds the combustion detection temperature, the heating means is Stop power supply.

EXAMPLE Hereinafter, a heating device according to an example of the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of a heating device according to an embodiment of the present invention.

Now, the outer shell 1 houses a heating chamber, etc., and the door body 2 closes the opening of the heating chamber so as to be openable and closable. Various commands are input from the keyboard 3 by the operator, and the input commands are deciphered by the control unit 4. Then, the control section 4 displays the input heating data and the like on the display section 5, and starts heating the object to be heated 7 placed in the heating chamber 6. Heating is performed by energizing the heating means 9.9° through the driver 8.8''. In this embodiment, a magnetron serves as the second heating means 91 that supplies microwaves to the heating chamber. An electric heater is provided as a first heating means 9 for raising the ambient temperature, the magnetron irradiates microwaves from a power supply opening on one wall of the heating chamber 6, and the electric heaters are arranged on the upper and lower surfaces of the heating chamber 6. The temperature inside the heating chamber 6 is raised to enable oven cooking by radiation and convection.

The temperature sensor 10 is a thermistor or the like, and detects the temperature inside the heating chamber 6 as a change in an electrical signal such as electrical resistance or voltage. The detection circuit 11 is an interface that connects the temperature sensor 10 and the control unit 4. For example, if a thermistor is used as the temperature sensor 10, it can be connected in series with a known precision resistor and a reference voltage applied to both ends. For example, the resistance value change of the thermistor can be read out as a voltage change, and this can be inputted to the A/D converter of the control section 4.

The temperature sensor 10 is provided in the exhaust guide 12 and monitors ventilation air in the heating chamber 6 forcedly ventilated by the fan 13.

Note that the mounting plate 14 is rotationally driven by a motor 15 to improve uneven heating of the object 7 to be heated.

Now, FIG. 1 is a time chart showing the control sequence of the present invention. (a) shows normal operation using microwave heating, and (b) shows a case where microwave heating is performed immediately after operating the oven. The heating chamber temperature refers to data detected by the control unit using a temperature sensor.

Here, there are two main points of the present invention. Firstly, combustion detection is performed only during microwave heating, and secondly, combustion detection is interrupted only for a certain mask time TM after the start of heating.

First, to explain the former, we have experimentally discovered that food in the heating chamber can catch fire and burn due to a malfunction or incorrect setting of the timer, but only with microwave heating.

I tried combustion tests on various foods, but for example, when heating one potato with microwaves, the high frequency output was 60
0 Watt products will definitely ignite in around 20 minutes.
It burned. However, when heated in the oven, 250
No ignition occurred even after 2 hours of operation at °C. Of course, the potatoes were charcoal-grilled, and if ignited with a pine tree, they would burst into flames instantly, but the bottom line is that it doesn't seem to reach the ignition temperature at 250°C. With microwave heating, as carbonization progressed, microwave sparks started inside the food, which eventually ignited and ignited, resulting in combustion.

From the above process, it can be concluded that combustion detection is sufficient only in the case of microwave heating.

Next, the latter (mask time) will be explained. In a composite heating device, microwave heating may be performed while the heating chamber is still hot after the oven is operated. At this time, it would be a problem if combustion was detected incorrectly and heating could not be started or was interrupted. However, raising the combustion detection temperature θF is a problem that the invention seeks to solve.

This leads to a decline in safety performance as described in . Therefore, the present invention lowers the combustion detection temperature θF to 100 to 120'C, which is the same as before.
By setting a mask time TM instead of a mask time TM, preparations were made for high-temperature operation after using the oven. That is, even if the temperature of the heating chamber exceeds the combustion detection temperature θF after the start of heating until the mask time TM has elapsed, this is ignored and the combustion detection operation is executed after 7M has elapsed.

With this sequence, as shown in Figure (b), even if the temperature immediately after the start of heating exceeds θF, it reliably falls below θF during TM, and does not cause any trouble to microwave heating.

To give an example, when the combustion detection temperature θF=120°C, the mask time TM is preferably about 4 minutes. With such settings, even when microwave heating was performed immediately after the oven was heated to 250°C, the temperature in the room decreased to 95°C after TM=4 minutes had elapsed. Especially since forced ventilation is provided by a fan, 110
'C quickly dropped to about
= 120°C, combustion could be detected just as well as conventional microwave ovens, and heating could be stopped approximately 1 to 2 minutes after ignition and combustion.

Next, a flowchart of an example of a control program when this control section is configured with a microcomputer is shown in FIG. 3 and will be described.

First, the initialization program executes RUNL, clearing the RAM, resetting the output ports, etc. (A).

Next, clocks are counted and basic data for various counters is created (B). This will be executed in hardware if the counter has a built-in counter. Subsequently, display data is output to display a predetermined display on the display section (C). Since dynamic lighting is generally used, display data for this purpose is created. Then, it is checked whether the heating device is in operation (D), and when it is not in operation, key human power is captured and deciphered (E). Cooking key and start key operations are decoded and processed here.

When it is confirmed that it is in operation during the operation check (D), it is first determined whether or not microwave heating is being performed (F).

In the case of microwave heating, first the mask time TM is counted by the TM counter (G). Next, it is determined whether a predetermined mask time TM has elapsed (H), 7
After M has elapsed, it is checked whether the heating chamber temperature θ has reached the combustion detection temperature θF (I). Therefore, combustion detection temperature θF
is stored in the ROM of the storage means Tal microcomputer.

Before the TM elapses, this combustion detection process is interrupted and the timer counts down (J). Further, even when combustion is not detected in item 1, the timer counts down (1), and when the timer ends (K), heating is stopped (L).

When combustion is detected in item 1 (when θ>θF), heating is stopped (L). With the above process, if the food ignites and burns in the heating chamber, this is quickly detected and the heating device can be safely stopped without flames blowing out of the machine. In addition, by setting the mask time, even if microwave heating is performed in a hot heating chamber state after using the oven, it is possible to reduce θ to θF by the time the mask time TM has elapsed, causing the heating to stop by mistake. You can avoid doing that.

Next, the sequence during oven operation will be explained.

When it is determined in the F term that microwave heating is not being performed, that is, oven heating is being performed, the temperature of the oven is first adjusted. In this embodiment, the same temperature sensor used for combustion detection is also used to adjust the temperature of the oven. Then, it is checked whether the heating chamber temperature θ has reached the set temperature θS (M), and if it has reached the set temperature θS, the heater is turned off (
N), the heater is turned on when it becomes less than θS (P). After such temperature adjustment processing, the process proceeds to timer processing.

The above is an example of a control program when the control section is configured with a microcomputer.

Next, another embodiment regarding the mounting position of the temperature sensor of the present invention will be described.

In FIG. 4(,), the temperature sensor is provided not in the exhaust guide 12 but in a part of the side wall of the heating chamber 6. In FIG. According to this, since the temperature sensor is close to the center of the heating chamber 6, the oven temperature can be adjusted satisfactorily.

FIG. 4(b) shows a temperature sensor attached in contact with the upper wall of the heating chamber. According to this, since the temperature sensor is not exposed to exhaust gas, it is possible to prevent dew condensation due to steam generated from food and a decrease in electrical resistance between the terminals.

Of course, the combustion detection temperature sensor and the oven temperature control temperature sensor can be configured separately.

Effects of the Invention As described above, the heating device of the present invention includes a temperature sensor that detects the temperature inside the heating chamber, counts the passage of the mask time TM by the counter means, and after the elapse of the mask time TM, the combustion stored in the storage means The detected temperature is compared with the temperature of the heating chamber detected by the temperature sensor, and when the combustion detection temperature is reached, the power supply to the heating means is stopped, and the following effects can be obtained.

(1) The combustion detection temperature can be set to a low value without considering the oven operating temperature, so even if food ignites and burns in the heating chamber during microwave heating, this can be quickly detected and the heating operation will be stopped. This can prevent fires from occurring.

■ A temperature sensor for combustion detection can be used to adjust oven temperature.

■ Even if the temperature sensor is broken, microwave heating can be performed during mask time. Usually microwave heating is 1-2
In most cases, it only takes about a minute, and if the mask time is about 4 minutes, even if the temperature sensor is damaged, microwave heating, which is used much more frequently than an oven, can be performed without any problem. Furthermore, if the sensor is also used as a temperature control sensor as in Section 2, the user will notice a malfunction during oven operation and call for service, thereby avoiding long-term use with the combustion detection function impaired.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a waveform diagram showing a method of detecting combustion in a heating device according to an embodiment of the present invention, Fig. 2 is a block diagram showing the same configuration, and Fig. 3 is a diagram of a microcomputer that is the control unit. The control flowchart, FIG. 4 is a sectional view showing another embodiment showing the mounting position of the same temperature sensor. 4...Control unit, 6...Heating chamber, 7...
...Object to be heated, 9.9゛...Heating means, 1
0...Temperature sensor, G...Counter means. Name of agent: Patent attorney Toshio Nakao and 1 other person11
Figure Or-Release number is D-M---Mask? 8-room F---liquid) Korigo hemorrhoids Figure 3

Claims (2)

[Claims] (1) a heating chamber in which an object to be heated is placed, a first heating means coupled to the heating chamber and raising the atmospheric temperature within the heating chamber, and a second heating means supplying high frequency waves into the heating chamber;
It consists of a temperature sensor that detects the temperature of the heating chamber, and a control section that controls power supply to the first and second heating means, and the control section has a counter means and measures a predetermined time from the start of heating. The counter means counts, and the temperature sensor stops detecting an abnormal temperature rise in the heating chamber until this time has elapsed, and after this time has elapsed, the storage means provided in the control unit detects the abnormal temperature rise. The heating device is configured to read out the temperature, and based on the reading, if the detected value of the temperature sensor reaches or exceeds the stored temperature, the control section stops power supply to at least the second heating means. (2) The heating device according to claim 1, wherein the abnormal temperature rise is detected by the temperature sensor while power is being supplied to the second heating means.