JPH0252772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a heating control device for a cooking device such as an electric stove.

Conventional configurations and their problems Conventional control devices in heating cookers such as electric stoves have been mainly ON/OFF controls, which change the energization rate and perform watt calls.
With this control, the temperature of the object to be heated in the pot placed on the stove is unknown, and the temperature depends on the user's patience. In addition, the temperature sensor installed in the center of the heater can be used to turn it on and off.
Some devices have a configuration in which the temperature is controlled by a pot, but as the temperature control varies depending on the material of the container such as the pot, the current situation is that its use is limited to specific pots.

Purpose of the Invention The purpose of the present invention is to provide a temperature control device that detects the temperature of the outer surface of a container such as a pot and controls the temperature of an object to be heated in the container, so that the temperature can be accurately maintained at a set temperature even when the material of the container is different. An object of the present invention is to provide a heating control device for a cooker that controls temperature.

Structure of the Invention The structure of the present invention includes a heating means such as a heater that heats a container such as a pot, and a temperature sensing element such as a thermistor that is in pressure contact with the outer surface of the container and indirectly detects the temperature of the object to be heated inside the container. , a temperature detection means that includes this temperature sensing element as a part, a temperature adjustment means that manually sets a temperature adjustment level from the outside, and a memory that stores the temperature set based on the temperature adjustment level set by this temperature adjustment means. a comparison means for comparing the set temperature stored in the first storage means and the temperature sensing element temperature obtained from the temperature detection means; and a comparison means for driving the heating means with the output of the comparison means. a driving means, and a peak temperature detection means for measuring the temperature of the temperature sensing element when the heating means is turned off for the first time after the start of heating based on the output of the comparison means and detecting the temperature immediately before the temperature starts to decrease, that is, the overshoot temperature;
A second storage means stores this peak temperature, and the difference between the temperatures stored in the first and second storage means, that is, the initial overshoot, is determined, and the setting stored in the first storage means is determined based on this temperature difference. It consists of calculation means for correcting the temperature. Said first and second
The storage means, comparison means, peak temperature detection means, and calculation means are means for processing inside a one-chip microcomputer.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the circuit configuration. In this configuration,
A relay contact 2 and a heating means 3 such as a heater are connected in series to both ends of an AC power source 1, and a DC power source 4 is connected thereto. The DC power supply 4 has a temperature sensing element 5 such as a thermistor.
and a resistor 6 are connected in series to constitute a temperature detecting means 7, and the connection point between the temperature sensing element 5 and the resistor 6 is connected to a microcomputer 9 via an A/D converter 8.
It is configured to be connected to and send a temperature signal. Similarly, a resistor 10 and a variable resistor 11 for manually setting the temperature adjustment level from the outside are connected in series to the DC power supply 4 to constitute a temperature adjustment means 12, and the connection point between the resistor 10 and the variable resistor 11 is A. It is connected to the microcomputer 9 via the /D converter 13 and sends a temperature control level signal. Further, a resistor 14 and a switch 15 are connected in series to the DC power source 4, and the connection point between the two is connected to a microcomputer 9 to send a heating control start/stop signal. The microcomputer 9 includes a first storage means 9a that stores the temperature set based on the temperature control level set by the temperature adjustment means 12, and the set temperature stored in the first storage means 9a and the temperature. A peak temperature detection means 9c for detecting the first overshoot temperature after the start of heating based on the output of the comparison means 9b for comparing the temperature sensing element temperatures obtained from the detection means 7, and a second storage means for storing this peak temperature. 9d and the temperature stored in the first and second storage means 9a, 9d, and based on this temperature difference, the first storage means 9
Calculating means 9e for correcting the set temperature stored in a.
is included, and the output from the comparison means 9b connects the resistor 1.
The configuration is such that the transistor 17 is driven through the relay coil 6 and the relay coil 18 is driven. A diode 19 connected in parallel with the relay coil 18 is for surge prevention. Resistor 16, transistor 17, relay coil 18, diode 19, relay contact 2
This constitutes the driving means 20.

Next, the appearance of an electric stove incorporating the heating control device for a cooker according to the present invention will be described using FIG. A start/stop switch 15 and a variable resistor 11 for temperature adjustment are provided on the side of the housing 21, and a saucer 22 is placed on the top surface.
A heating means 3 is provided at the top, and a temperature sensing element 5 is provided at the center of the heating means 3. When a container such as a pot is placed on the heating means 3, the temperature sensing element 5 is pressed against it by a spring (not shown).

Next, the operations performed by the microcomputer 9 will be explained using the flowchart shown in FIG. When the power is turned on and the switch 15 is turned on, the temperature control level set by the variable resistor 11 is input in step 1, the temperature is temporarily set in step 2, and the temporary setting value T _p is set to the first value. Storage means 9
Put it in RAM which is a. In step 3, input the temperature T of the temperature sensing element 5. In step 4, turn on the heating means 3 until the temperature T of the temperature sensing element 5 becomes larger than the previous provisional setting value _Tp , and repeat in step 4. When the temperature T of the temperature sensing element 5 exceeds the temporary set value _Tp , the heating means 3 is turned off in step 6.
Start overshoot measurement in the next step. In step 7, input the temperature T of the temperature sensing element 5,
In step 8, the peak value _Tp is obtained by repeating the process until the temperature T starts to decrease, and in the next step 9, it is stored in the RAM, which is the second storage means 9d. Next, in step 10, the value of T _p -T _p is calculated and the temporary temperature setting value T _p is corrected according to this value and changed to T ₁ .
The temperature is controlled by repeating ON/OFF control with the set temperature set as _T1 .

Next, a specific method for modifying the above T _p and changing it to T ₁ will be described using as an example a case where oil is placed in a container and controlled. This modification overshoots T _p −
This can be achieved by storing in advance in the ROM of the microcomputer 9 a value determined by the correlation between T _p and the deviation T _L −T _p of the oil temperature T _L from the set temperature T _p . Hereinafter, the explanation will be given again with reference to the drawings. Fourth
The figure shows the change in sensor temperature and oil temperature over time when general ON/OFF control is performed. Overshoot T _p −T _p and oil temperature deviation T _L −T _p can be seen, but as explained with the actual measurement data in FIG. 5, this varies greatly depending on the material of the container. In a stainless steel pot, the oil temperature is around 186℃, which is on the + side compared to the set value of 180℃. On the other hand, in the case of an iron pot, the heat is shifted to one side, and this tendency is even more pronounced in the case of an aluminum pot, which has good heat conduction. Therefore, when using a pot made of the three types of materials mentioned above with a plate thickness of 1 mm to 3 mm, a control temperature range of 14.5 degrees is created as shown in the figure, even without including other variation factors.
You can see that even if the settings are the same, the oil temperature will change significantly if you change the pot. However, since this figure shows an almost linear correlation diagram,
It can also be seen that the oil temperature T _L can be controlled by the overshoot T _p −T _p .

Next, FIG. 6 shows temporal changes in sensor temperature and oil temperature when controlled based on the present invention. After detecting the first overshoot T _p −T _p , the set temperature T _p
is controlled by changing it to T ₁ to obtain the oil temperature T _L. In this case, the amount of change ΔT is the difference between the set temperature T ₁ and the oil temperature T _L
It is desirable to match T _L −T ₁ . Specifically, based on the measured data shown in Figure 5, the overshoot of 0 to 4deg is corrected by +6deg, and the set temperature T _p is adjusted by 3deg for each 4deg increase in the overshoot.
If you lower the temperature and determine the corrected set temperature T ₁ as shown in Figure 7, the discrepancy between the set temperature and oil temperature due to the pot material and plate thickness will be extremely reduced.
The deviation width from 14.5deg becomes 2.5deg. Since enamel pots and the like are estimated to have a thermal conductivity between that of stainless steel pots and iron pots, this control method covers most pots that fall within this control range and are used on electric stoves, ensuring accurate temperature. can tune. The microcomputer may store correction values for the overshoot every 4 degrees in the ROM.

Effects of the Invention As explained above, by using the heating control device for a cooker according to the present invention, the temperature of the object to be heated such as oil in the container can be accurately controlled according to the set temperature even when the container material and plate thickness are different. can be controlled. It goes without saying that the same control can be applied even when oil turns into water. It is also possible to suppress the temperature rise due to overshoot by setting the temporary set temperature mentioned above a little lower, and it is also possible to suppress smoke generation and oil deterioration when the load is oil.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a device according to an embodiment of the present invention, Fig. 2 is an external view of an electric stove incorporating the same device, Fig. 3 is a flowchart of a microcomputer, and Fig. 4 is an ON/OFF control Fig. 5 is a graph showing the correlation characteristic between overshoot and oil temperature deviation, and Fig. 6 is a graph showing the change in sensor temperature and oil temperature over time in the control of an embodiment of the present invention. The change characteristic diagram, FIG. 7, is a diagram showing the deviation width of the oil temperature under control by the same device. 3... Heating means, 5... Temperature sensing element, 7... Temperature detection means, 9... Microcomputer, 12...
...Temperature adjustment means, 20...Driving means.

Claims (1)

[Claims] 1. A heating means such as a heater that heats a container such as a pot, a temperature sensing element such as a thermistor that is pressed against the outer surface of the container and indirectly detects the temperature of the object to be heated inside the container, and a part of this temperature sensing element. temperature detection means,
A temperature control means for manually setting a temperature control level from the outside, and a first temperature control means for storing a temperature set based on the temperature control level set by the temperature control means.
storage means, comparison means for comparing the set temperature stored in the first storage means and the temperature sensing element temperature obtained from the temperature detection means, and drive means for driving the heating means with the output of the comparison means. and a peak temperature detection means for detecting the first overshoot temperature after the start of heating based on the output of the comparison means, a second storage means for storing this peak temperature, and first and second storage means. A heating control device for a cooker comprising calculation means for determining a difference between stored temperatures and correcting a set temperature stored in a first storage means based on this temperature difference.