JPH01146284A - Heater - Google Patents

Abstract

PURPOSE:To improve safety with an early detection of burning of an object to be heated in a heating chamber by measuring a temperature gradient after a certain period from the time point where a control temperature is reached and turning a heater off as well as issuing a warning if the temperature balance is determined to be abnormal. CONSTITUTION:Detecting the burning of an object to be cooked by measuring the temperature in heating chamber at the time of cooking and comparing the change in the condition with that of a standard condition, heating is stopped and a warning is issued. In the case of heat cooking, detection of burning of the object to be cooked is very difficult if the absolute value of the measured temperature is used because of a high value of the controlled temperature. Namely, the temperature change is approximately constant in the case temperature control is normally repeated. If the heated object burns, however, the temperature balance is disturbed by the energy of the burning and the temperature differs relatively from that of a normal condition. Detecting such a condition, the burning can be detected early and securely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a device for preventing excessive temperature rise in a heating chamber of a cooking device equipped with a heater.

2. Description of the Related Art In conventional heater-added heating devices, a bimetallic switch for preventing excessive temperature rise was attached to the surface of the heating chamber of the heating device. As a result, even if the object to be heated in the heating chamber ignites, the heat from the ignition will eventually activate the overtemperature rise prevention device, and the power will be turned off.

Problems to be Solved by the Invention However, in the case of the temperature overrise prevention switch, the temperature inside the heating chamber may reach 250°C to 300'C during cooking with the heater, and in this state, if the food inside catches fire, In order to operate this switch, a very precise switch was required, and it was difficult to control it without malfunction. Therefore,
Conventionally, this has been addressed by increasing the temperature at which this switch operates. Therefore, even if the food ignites, it cannot be detected immediately, and if the amount of food to be cooked is small, the temperature may not reach this level and the fire cannot be detected.

The present invention solves these conventional problems, and provides highly safe heating that can detect ignition of the object to be heated in the heating chamber at an early stage and stop heating even in high-temperature conditions during cooking with a heater. It provides equipment.

Means for Solving the Problems The heater additional heat device of the present invention includes a heating chamber, a temperature measuring means for measuring the temperature inside the heating chamber, a heater control means for controlling ON/OFF of the heater, and a control temperature for cooking in advance. a control temperature setting means for setting, a temperature comparison means for comparing a measured temperature input by the temperature measurement means and a set temperature input by the control temperature setting means, and a temperature change detection means for detecting a change in the measured temperature. , a temperature change slope calculation means for calculating the slope of the change, a temperature change standard slope storage means for storing the value as an average of a plurality of times, and a temperature change standard slope storage means for storing the value as an average of a plurality of times, A temperature change slope comparison means that measures the slope and compares the standard value and the measured value during the temperature control state, and when the comparison means determines that the temperature balance in the heating chamber is abnormal,
The abnormality notification means is used to notify and turn off the heater.

Function: The heater additional heat device of the present invention measures the temperature inside the heating chamber during cooking and compares the state of change with the standard state, thereby detecting combustion of the food being cooked, stops heating, and notifies the user of the report. It is something. In the case of heater heating cooking, since the control temperature is high, it is very difficult to detect the ignition of the object to be heated using the absolute value of the measured temperature, and therefore it is difficult to detect it even with a switch such as a bimetal. However, there is always a change in the relative value. In other words, when the temperature is normally controlled repeatedly, the temperature change is almost constant, but if the heated object ignites in this state, the energy The balance of temperature changes is disrupted, making it relatively different from the previous normal state. By detecting this, combustion can be detected early and reliably. Therefore, compared to conventional methods, heating equipment is less likely to be destroyed due to combustion. It is now possible to provide a heater additional heat device that is small in size and can prevent the spread of fire to the surrounding area, making it possible to provide a safer heater additional heat device.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. FIG. 2 shows a sectional view of a microwave oven with a heater according to an embodiment. A heater 15 and a magnetron 16 that heat an object to be heated 14 are connected to the heating chamber 13 . Heating chamber 1
1 is measured by a thermistor 17.

As shown in FIG. 1, the temperature of the heating chamber is measured by a temperature sensor manual means 1 using a thermistor. Further, during heating, the controlled temperature is inputted in advance by the control temperature setting means 2 by manual keystroke or the like. The temperature comparison means 3 which compares the information from these two input means controls the heater 1 through the heater control means 11 when the measured temperature is the set temperature.
Turn on 2. Conversely, if the measured temperature ≧ the set temperature,
Similarly, the heater 12 is turned off, but since the heater 12 is continuously energized until it enters this state for the first time after cooking starts (in this case, the start-up state), the amount of energy supplied is large. The information from sensor human power means 1 has significant overshoot. After this, temperature control is repeated until the temperature is controlled at approximately constant intervals (n1 = unstable period) and thereafter (stable period). Next, the mask counting means 4 counts the aforementioned unstable period n1 time, and after the count ends, that is, when the stable period begins, the temperature change detecting means 5 detects a change from the information from the temperature sensor manual means 1,
The temperature change slope calculation means 6 calculates the upward slope and downward slope. After entering the stable period, this slope value is averaged by the temperature change slope comparison means 7 for 12 periods (standard slope measurement period), and the average upward standard slope value and average downward standard slope value are determined and stored in the temperature change standard memory. The information is stored in means 8. Here, if food ignites or the like and the energy supply balance is disrupted, the slope will differ from the stored standard slope value. That is, after the 02 period, the temperature change slope comparison means 7 compares the measured slope value calculated by the temperature change slope calculation means 6 and the standard slope value stored in the temperature change standard storage means 8, and The abnormality detection means 9 makes a judgment based on the size comparison, and turns off the heater 12 through the heater control means 11, and the abnormality notification means 10 notifies the abnormality by means of a display, a buzzer, or the like. Figure 3 shows
This is a flowchart of the control program, which allows the above-mentioned functions to be realized by a controller such as a microcomputer. FIG. 4 is a graph of the above-mentioned thermistor's change over time, showing a rising state, an unstable period, and a stable period.

FIG. 5(a) shows the change in the thermistor during the stable period.

As shown in the figure, the slope in the downward direction is 1-1 due to ΔT1 and Δt1.
2=ΔT2/ due to ΔT1/Δt1 and ΔT2 and Δt2
Δt2 is stable. However, when the object to be heated ignites as shown in Figure 5(b), the upward curve becomes Δt due to the energy supplied from the heater and the energy from the ignition.
4 is short (the downward curve has a long Δt3. In other words, the slope of 3=ΔT3/Δt2 and 4=ΔT4/Δt4 is 1>K3.2<K4 compared to the above-mentioned 1 and 2. As a result, detection can be performed almost at the same time as the ignition.

Effects of the Invention As described above, in the heating device of the present invention, the slope of the change in the thermistor is detected by comparing it with a standard value, and ignition of foods, etc. can be detected quickly, and a safe heating device can be provided. This eliminates the need for an overtemperature protection switch, resulting in cost reduction. Further, the present invention can be realized by a microcomputer program, which is advantageous in terms of cost and noise caused by external causes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram in one embodiment of the present invention, and FIG.
3 is a flowchart of the control program, FIG. 4 is an operational waveform diagram during heating, and FIG. 5 is a detailed temperature waveform diagram. 1...Temperature sensor manual means, 2...
Control temperature setting means, 3...Temperature comparison means, 4.
... Mask counting means, 5 ... Temperature change detection means, 6 ... Temperature change slope calculation means, 7
... Temperature change slope comparison means, 8 ... Temperature change standard storage means, 9 ... Abnormality detection means, 1
o... Abnormality notification means, 11... Heater control means, 12... Heater. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 1 (Figure 5)

Claims (4)

[Claims] (1) A heating chamber, a temperature measuring means for measuring the temperature inside the heating chamber, a heater for heating the food to be cooked in the heating chamber, a heater control means for controlling ON/OFF of the heater, and a control temperature for cooking in advance. a control temperature setting means for setting;
Temperature comparing means for comparing the temperature measured by the temperature measuring means with the control temperature, means for detecting a change in the measured temperature, temperature change slope calculating means for calculating the slope of the temperature change, A temperature change standard slope storage means for storing a value as an average of a plurality of times, and a value calculated by the temperature change slope calculation means and a standard value previously stored in the storage means when the temperature is controlled at a controlled temperature during heater cooking. A heating device comprising a temperature change slope comparison means for detecting the temperature balance in a heating chamber by comparison, and an abnormality detection means for activating an abnormality notification means when the balance is determined to be abnormal. (2) The heating device according to claim 1, further comprising means for taking a delay time from the time when the temperature control state is entered for the first time until the time when the temperature change slope is calculated. (3) A configuration in which the heating chamber temperature is searched by the temperature measurement means when an abnormality is determined by the abnormality detection means, and when it is determined that the temperature is at a dangerous temperature, the heater is turned off by the heater control means to stop further heat generation. A heating device according to claim 1. (4) Claim 1, in which the temperature measuring means is configured to turn off the heater and stop further heat generation when the temperature continues to rise even though the heater is off.
Heating device as described in section.