JPH0252489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature control device for a cooking device that detects boiling by utilizing the fact that when water boils, the temperature rise rate decreases.

BACKGROUND ART In conventional temperature control devices of this kind, since the rate of temperature increase after boiling becomes small, some have compared it with a predetermined standard to detect boiling.

Problems to be Solved by the Invention However, according to these means, although the temperature rise curve differs depending on the temperature at the start of heating, as shown in FIG. Since the reference value is determined based on ,
Further, when the temperature at the start of heating is high, the reference value becomes small, and as a result, there is a problem that it takes a long time to stop heating after boiling, that is, so-called "late cut-off" occurs.

An object of the present invention is to provide a temperature control device for a heating cooker that solves these problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention selects a comparison reference value based on the temperature of the object to be heated at the start of heating and supplies it to the inclination detection means.

Effect According to the above configuration, a longer reference value can be given to a heated object that tends to burn out quickly, and a shorter reference value can be given to a heated object that tends to burn out later, resulting in stable heating. boiling detection can be performed.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. FIG. 1 is a block diagram of a temperature control device for a heating cooker showing an embodiment of the present invention, in which 1 is a temperature detection element consisting of a thermistor that detects the temperature of the object to be heated, and its output signal is sent to the initial temperature determination means. 2
The temperature is then compared with a predetermined temperature. Reference numeral 3 denotes a comparison standard selection means, which selects the first reference value 4 according to the output of the initial temperature determination means 2 when the temperature is above a predetermined temperature, and on the other hand, when the temperature is below a predetermined temperature. In this case, the second reference value 5 is selected. Further, the output signal of the temperature detection element 1 is also sent to the temperature increase rate detection means 6, and the temperature increase rate is detected. Reference numeral 7 denotes an inclination detection means, and this inclination inclination means 7 compares the data detected by the temperature increase rate detection means 6 with the reference value selected by the comparison reference selection means 3, and compares the data detected by the temperature increase rate detection means 6 with the reference value selected by the comparison reference selection means 3. Then,
The output is transmitted to the heating control means 8, and the heating control means 8 stops heating. 9 is resistance.

FIG. 2 shows a specific circuit configuration of an embodiment of the present invention.
b is a resistor, 2c is a comparator, and these are the first
This constitutes the initial temperature determination means 2 shown in the figure. 6a is a resistor, 6b is a capacitor, 6c is a comparator, 6d is a transistor, and 6e is a counter A, which is a so-called A/D that measures the charging time of an integrating circuit consisting of a resistor 6a and a capacitor 6b and obtains information proportional to temperature. The converter 6f is another counter B, which obtains information regarding the rate of temperature rise based on the information from the counter A. These constitute the temperature rise detection means 6 shown in FIG. The information is sent to the double calculation means 6g and the triple calculation means 6h.
are transmitted to the first reference value 4 and the second reference value 5. 8a and 8b are transistors and a power source for driving a relay 8c consisting of a relay coil 8c' and a relay contact 8c'', 8d is a heating heater, and 8e is a commercial power source, and these constitute the heating control means 8. .10 is a microprocessor.

Next, the flow of processing in one embodiment of the present invention will be explained. Figure 3 shows the process of obtaining temperature information to _and temperature increase rate information T based on the charging time of the capacitor 6b.
111 and 112 are initialization. In step 113, the output of the comparator 6c is checked, and if it is Low, it means that charging has not been completed, so in steps 114 and 115, to _and T are counted up, respectively, and the process returns to step 113.
While repeating the loop of steps 113 to 115 described above, the charging potential of the capacitor 6b reaches the thermistor 1.
When the voltage becomes equal to the potential divided by the resistor 9 and charging is complete, a step branching from step 113 is executed.
Proceed to step 116 and compare the previously measured charging time t _o-1 with t _o . Here, t _o increases as the temperature rises, so if the temperature is higher than the previous time, t _o >
t _o-1 , whereas if the temperature is not rising, t _o
≦t _o-1 . If t _o ≦ t _o-1 , step
Return to 112 and press T while timing the charging time again.
Continue to count up. Eventually t _o ≧t _o-1
Then, the time T required for the temperature to rise by one temperature category can be obtained. This time T is the reciprocal of the rate of temperature rise.
These conditions are shown in FIG. As an example, t _i =
It is set at 100-103. When the temperature reaches about 70°C, the time T obtained as described above is doubled by the calculation means 6g, 3.
The data are sent to the multiplication means 6h and used as the first reference value and the second reference value, which are then selected by the comparison reference selection means 3 and sent to the inclination detection means 7. On the other hand, the time T required to rise by one temperature category, which is successively obtained, is compared with a reference value by the slope detection means 7, and the time T required to rise by one temperature category is compared with the reference value by the slope detection means 7. At this time, the output is transmitted to the heating control means 8. As described above, the process flow from the start of heating until the heating is stopped by detecting the inclination is explained in the fifth step.
As shown in the figure. In this way, by selectively using two types of reference values based on the temperature at the heating start point, stable boiling detection can be performed without premature or late termination.

Effects of the Invention As described above, according to the present invention, stable boiling detection with good performance can be performed with an extremely simple circuit configuration and simple processing.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a temperature control device for a heating cooker showing an embodiment of the present invention, Fig. 2 is a specific circuit diagram of the temperature control device, and Fig. 3 is a temperature rise rate of the temperature control device. 4 is a characteristic diagram for explaining the correlation between the temperature and internal data of the temperature control device, and FIG. 5 is a flowchart showing the overall processing flow of the temperature control device. , FIG. 6 is a characteristic diagram for explaining the temperature increase rate of a conventional temperature control device. DESCRIPTION OF SYMBOLS 1...Temperature detection element, 2...Initial temperature determination means, 3...Comparison standard selection means, 6...Temperature increase rate detection means, 7...Inclination detection means, 8...Heating control means.

Claims (1)

[Claims] 1. A temperature detection element that detects the temperature of the heated object;
temperature increase rate detection means for detecting the rate of change in the temperature detected by the temperature detection element; initial temperature determination means for comparing and determining the temperature detected by the temperature detection element and a predetermined temperature at the start of heating; Comparison standard selection means for selecting a first reference value when the temperature is above the predetermined temperature and a second reference value when the temperature is below the predetermined temperature based on the judgment output; The temperature of the heating cooker is composed of a slope detection means that compares the output of the increase rate detection means and detects that the temperature has fallen below a reference value, and a heating control means that stops heating upon receiving the output of the slope detection means. Control device.