JPH01105496A - Heated cooking utensil - Google Patents

Abstract

PURPOSE:To prevent the unnecessary heating of an equipment and prevent the wasteful power consumption by providing a heating time calculating means outputting the heating stop signal or the heat preserving signal to a control device when the boiling detecting function of the equipment is not operated after the heating state of the equipment continues for a fixed time. CONSTITUTION:A heating time detecting means 27 which receives the output from a timer device 22 and inputs the duty signal to an inverter control means 16 and periodically turns on or off the oscillation of an inverter device 17 to maintain the hot water temperature in an object to be heated 14 in a heat preserving state or completely stops the inverter device 17 is incorporated in a microcomputer 20. Even when the object to be heated has a camber on the bottom and the boiling detecting function of the equipment is not operated, the input of the equipment is stopped or reduced after a fixed time, thus the wasteful power consumption of the equipment is suppressed, and the empty heating of the object to be heated due to the continuous heating after the boiling of hot water can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a cooking device equipped with a boiling detection function using a signal from a heat-sensitive element such as a thermistor.

21.-7 Prior Art An induction heating cooker will be described as an example of a conventional heating cooker equipped with a boiling detection function. That is, as shown in FIG. 4, the temperature of the heated object 2 heated by the heating coil 1, which is the heating section, is controlled by a heat-sensitive element 4 such as a thermistor, which is pressed under the top plate 3 made of an insulating material such as ceramic. Detected. This heat-sensitive element 4 is connected to a resistor 5, and this divided voltage signal is outputted to a boiling detection device 7 built in a one-chip microcomputer 6.

This boiling detection device 7 has a timer device 8 as shown in FIG.
sampled every 91 seconds, and A/D converter 9
The temperature gradient of the D-converted heat-sensitive element 4 (the time it takes for the temperature of the heat-sensitive element 4 to rise by 2°C) is determined when KN becomes twice the reference gradient of 1 at the time when detection is started. In the case where the gradient detecting means 1o is used, as shown in FIG.
l1m1t, and makes a determination when T≧Tl1m1t, which is the case using the absolute temperature detection means 11, is used.If either of these detection means outputs, The boiling state was notified by outputting an output from the OR circuit 12 and lighting up a light emitting element 13 such as a LIED.

Problems to be Solved by the Invention However, with such a detection means, if there is a warp on the bottom of the heated object 2, there is a difference between the temperature of the heat sensitive element 4 and the water temperature inside the heated object 2. There is a difference in the kana shi compared to the case where the bottom of 2 is flat. Therefore, if the amount of hot water in the object to be heated 2 is small, even if the hot water reaches a boiling state, the temperature TN of the heat-sensitive element 4 will not easily reach the upper limit Tl1m1t.
Moreover, because the temperature continues to rise slowly, it cannot be detected even by the temperature gradient of the heat-sensitive element 4, and the equipment continues to heat up unnecessarily, consuming unnecessary power and causing the hot water in the object to be heated 2 to evaporate. There was also a risk that the system would end up being left empty-cooked.

Therefore, in view of the above-mentioned problems, the present invention stops the heating of the equipment or automatically reduces the input of the equipment, independently of the boiling detection function, if the equipment continues to heat for a certain period of time without detecting boiling. The purpose is to prevent unnecessary heating of equipment and the consumption of unnecessary electricity by switching to keep-warm cooking.

Means for Solving the Problems In order to achieve the above object, the induction heating cooker of the present invention includes:
When the appliance is in boiling water mode, the heating time can be measured.
The configuration includes a heating time calculation means that outputs a heating stop signal or a heat retention heating signal to the control device when the boiling detection function of the equipment does not operate even if the heating state of the equipment continues for a certain period of time.

Effect: With the above configuration, even if the boiling detection function of the device does not work due to warping at the bottom of the object to be heated during boiling water cooking, the input to the device stops or decreases after a certain period of time, so the device becomes useless. It is possible to reduce power consumption, and also to prevent the heated items from being heated due to continuous heating after the water has boiled.

EXAMPLE Hereinafter, an induction heating cooker according to an example of the present invention will be explained with reference to FIGS. 1, 2, and 3.

In the configuration of this embodiment, as shown in FIG. 1, an object to be heated 14 is placed on a top plate 13 made of ceramic on the top surface of the device. A heating coil 15 serving as a heating section is installed below the top plate 13. When the user turns on the input switch (not shown) of the device, the inverter oscillation means 1 controls the heating coil 15 which is the heating section.
6 receives the ON signal and causes the inverter device 17 to oscillate, causing a high frequency current to flow through the heating coil 15.
The object to be heated 14 is heated by induction.

Here, when the device detects boiling of the water in the object to be heated 14, the temperature of the water in the object to be heated 14 is indirectly detected by the thermistor 18 that is pressed against the bottom surface of the top plate 13, and the temperature of the water increases. At the same time, the temperature of the thermistor 18 increases and the resistance value of the thermistor 18 decreases. This change in resistance value is input as a divided voltage signal between the thermistor 18 and resistor 19 to the A/D converter 21 in the one-chip microcomputer 20 that controls the boiling detection function. At the same time, when heating of the equipment is started, the timer device 22 in the microcomputer 206-1 starts counting the heating time. The output from the A/D converter 21 and the signal from the timer device 22 serve as two types of boiling detection means: an absolute temperature detection means 23 of the thermistor 18 and a temperature gradient detection means 24 of the thermistor 18. When the input is input to the detection means 25 and either the absolute temperature detection means 23 or the temperature gradient detection means 24 detects boiling of the water in the object to be heated 14, the microcomputer 20 outputs power from a light emitting element 26 such as an LED to emit light. The element 26 lights up to notify the user of the boiling state. Also, in the microcomputer 20, in addition to this boiling detection means 26, in response to the output from the timer device 22, if the boiling detection means 26 does not output even if the heating state continues for 17 minutes, the inverter control means 16 is activated. Heating time detection means 27 which controls the function of inputting a duty signal and periodically turning on and off the oscillation of the inverter device 17 to maintain the temperature of the hot water in the object to be heated 14 in a warm state.
It has a built-in configuration.

Next, the operation when there is a warp 7' at the bottom of the object to be heated 14 as shown in FIG. 1 will be explained using the flowchart in FIG. This will be explained using figures. The user turns the input switch (not shown) on the device to O.
NL, when boiling water starts cooking, the timer device 22 of the microcomputer 2o is started, and after timing for 3 minutes to ignore the fluctuation 28 of the temperature curve in the initial heating state of the water temperature, A/ A/D converter 21
The D-converted temperature signal of the thermistor 18 is input to the boiling detection means 25. Then, the absolute temperature detection means 23 compares the thermistor 18 temperature TN N seconds after heating with the thermistor 18 temperature upper limit value Tl1m1t, and determines that TN>T.
If it is l1mlt, it is determined that there is a boiling state, and the light emitting element 26 is turned on. Also, if T, 16111m1t, the rate of increase KN after N seconds calculated by the slope detection means 24 from the output from the MU/D converter 21 and the output from the timer device 22 (here, the thermistor temperature increases by 2 degrees) Compare 1 with the initial rate of increase calculated 3 minutes after the start of heating, and calculate 1 (-Klimit) with KN>2.
), the gradient detection means 24 determines that the boiling state is present, and lights up the light emitting element 26. However, if the bottom of the object to be heated 14 is warped, the temperature of the thermistor 18 will have a larger difference from the water temperature than when the bottom of the object to be heated 14 is in close contact with the top plate 13.

In addition, if the amount of hot water in the heated object 14 is small,
Even when the water is boiling, the thermistor temperature TN remains Tl1m.
Since the temperature is low compared to 1t, and the temperature continues to rise slowly even after boiling, it is difficult to achieve the above-mentioned state of KN>K11m1t, so the boiling detection means 26 does not operate properly. Therefore, when TN < Tl1m1t, the absolute temperature detection means 23 of the thermistor 18 and when xH<xlimit, the slope detection means 2
4 does not notify boiling, if the heating time detecting means 27 calculates the output from the timer device 22 and determines that the elapsed heating time t has exceeded 17 minutes, the inverter controlling means 16 controls the microcomputer 20. By inputting a duty signal from the boiler and switching the device to warm cooking, it is possible to prevent the device from consuming unnecessary power due to continued heating for a long time after the water has boiled.

In this embodiment, the output force signal of the heating time detection means 27 is the duty control signal of the inverter device 17.
Although the explanation has been made assuming that there is a signal, it goes without saying that the signal may be a signal that completely stops the inverter device 17.

Effects of the Invention As is clear from the above embodiments, according to the present invention, the bottom surface of the object to be heated, such as a pot for boiling water, is warped and the water temperature detection sensitivity of the heat-sensitive element is slow, and even when the water boils, Even if the boiling detection function of the device does not work and heating continues for a long time, the device will calculate the heating time of the device and automatically turn off the input power after a certain period of time and enter the warming state or heating stop state. Therefore, it is possible to prevent unnecessary power consumption due to unnecessary heating of the equipment, improve economic efficiency, and prevent the heating of the heated items.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main parts of an induction heating cooker according to an embodiment of the present invention, Fig. 2 is a flowchart showing an example of a programming diagram of the induction heating cooker, and Fig. 3 is a heated product with warp on the bottom surface. Figure 4 is a block diagram of the main parts of the boiling detection function of a conventional induction heating cooker, and Figure 6 is a diagram of temperature characteristics during boiling water cooking with an induction heating cooker when boiling water with food. It is a temperature characteristic diagram showing the same boiling detection function. 13... Top plate, 14... Heated object, 16... Heating coil, 16...
- Inverter control means, 17... Inverter device, 22... Timer device, 25... Boiling detection means, 27... Heating time detection means. Name of agent: Patent attorney Toshio Nakao and 1 other person H3
---1-,,y7・7・し=卜Figure 4Figure 5

Claims (1)

[Claims] A heating section that heats an object to be heated, a control device that controls the heating section, a heat-sensitive element that indirectly detects the water temperature of the object to be heated, and a temperature of the object to be heated based on a signal from the heat-sensitive element. a temperature detection means for detecting a temperature; a boiling detection means for detecting boiling of the object to be heated based on a signal from the temperature detection means; A heating cooker comprising a heating time detection means for outputting a heating stop signal or a heat retention heating signal to the control device when the boiling detection means does not operate even after a period of time has elapsed.