JPS648249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cooking device that automatically detects boiling depending on the amount of water in a heated container and then controls the temperature.

Conventional configurations and their problems Some conventional heating cookers control the amount of electricity applied to the heating element, but when boiling water, the amount of electricity applied must be set according to the amount of water, which is a problem. It was hot. Also, if you want to shorten the time until boiling, you can maximize the amount of electricity, but after boiling, you will waste electricity, and conversely, if you reduce the amount of electricity, There was a problem that it took a long time.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems, and is capable of automatically detecting the boiling of water in a container, heating to the maximum until boiling, and heating after boiling according to various uses. The object of the present invention is to provide a heating cooker that can control the temperature.

Structure of the Invention In order to achieve the above object, the heating cooker of the present invention includes a heating element that heats a container containing water, a temperature sensor that is brought into contact with the container, and a temperature detected by the temperature sensor. a temperature rise rate measuring means for measuring the temperature rise rate of water using as an input signal; and a boiling detection means for detecting the boiling point when the temperature rise rate becomes equal to or less than a predetermined value based only on the measurement signal from the temperature rise rate measuring means. a temperature comparator for comparing the temperature after the boiling point detected by the boiling point with a predetermined temperature slightly lower than the boiling temperature at the boiling point detected by the temperature detector; and an output of the temperature comparator to detect the heat generation. The heating element control means controls the electricity supply to the body.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a plan view of a heating cooker according to an embodiment of the present invention, in which 1 is a heating element and 2 is a temperature sensing element. When a container filled with water is placed on top of the heating element 1, the temperature sensing element 2 comes into contact with the bottom of the container. 3 is a power switch, and when this power switch 3 is turned on, it starts operating.

FIG. 2 shows a block diagram of a heating cooker according to an embodiment of the present invention, and the same components as those shown in FIG. 1 are given the same numbers.

In FIG. 2, 1 is a heating element that heats a container 4 containing water, and 5 is a temperature detector placed in contact with the container 4. This temperature sensor 5 measures the temperature of the container 4 containing water. The detected temperature signal is input to the temperature increase rate measuring means 6, which measures the temperature increase rate of the water, that is, the slope of the temperature curve. This measurement result is then given to the boiling detection means 7, which compares the rate of temperature rise (slope of the temperature curve) with a predetermined value, and when the rate of temperature rise becomes less than the predetermined value, the boiling point It is determined that the boiling point has been reached and the boiling point is detected. In other words, this is the point when the temperature no longer increases (water is 100℃)
It is. Then, a temperature slightly (2 to 3° C.) lower than the value (temperature data) of the temperature detector 5 at that time is given to the next temperature comparator 8. The temperature comparator 8 compares the temperature with the temperature detected by the temperature detector 5, and based on the result, the heating element control means 9 controls the supply of electricity to the heating element 1.

FIG. 3 shows the circuit configuration of the heating cooker in this embodiment, and the same components as those shown in FIGS. 1 and 2 are given the same numbers.

In FIG. 3, reference numeral 5 denotes a temperature detector, which is made up of a series circuit of a temperature sensing element 2 and a resistor 10. The output from the temperature detector 5 is input to the microcomputer 12 via the A/D converter 11. The output of this microcomputer 12 is the transistor 1
3 to turn on the photocoupler 14. When this photocoupler 14 is turned on, a current flows from the DC power supply 15 to the gate of the thyristor 16, and the thyristor 16 becomes conductive.
Electric power is supplied to the heating element 1 . In this way, the heating element control means 9 is configured. Note that 17 is an AC power source.

Next, the operation of the microcomputer 12 will be explained based on the flowchart shown in FIG. When the power switch 3 is closed, the heating element 1 is turned on in step
output to the output port so that the heating power is maximized. That is, the output port becomes "H" and the thyristor 16 continues to be conductive. In this step, the digitally converted temperature data from the temperature detector 5 is input, and the system waits until the temperature (70°C) at which the temperature rise rate measurement is to be started. When the measurement start temperature is reached, the rate of temperature rise is measured in steps as shown below. The temperature rise rate measuring means 6 is configured to measure the temperature rise ΔT after a certain period of time. That is, measure the current temperature T _o and wait for a certain period of time (30 seconds)
Measure the subsequent T _o+1 and calculate T _o+1 − _{T o} =ΔT. Next step is to detect boiling. The boiling detection means 7 is configured to compare the temperature increase ΔT with a constant value A (approximately zero) and determine the boiling point when ΔT becomes smaller than A. In other words, it takes advantage of the fact that once water reaches its boiling point, the temperature stops rising. Therefore, while ΔT is greater than A,
Return to the step again and repeat the measurement of ΔT.
During this time, the heating power is at its maximum.

When the boiling point can be detected, the step moves to step 2, where the temperature of the temperature detector 2 at a predetermined temperature, for example 70°C, is compared, and the heating element control means 9 is operated in step 2 according to the comparison output to start heating. The temperature is controlled to a predetermined temperature by starting and stopping.

As described above, in one embodiment of the present invention, boiling is automatically detected and the temperature is then adjusted to a predetermined temperature, for example, 70°C, so that the user can immediately control the hot water after boiling is detected. The cooking device is equipped with a boiling detection function that allows you to keep the food warm without using it.

In the above example, the temperature was adjusted to 70℃, but ΔT<A
By controlling the temperature to a temperature slightly lower than the temperature at which the temperature reaches , it is possible to maintain an almost boiling state with less power. In other words, water starts boiling at around 95℃ and does not rise above 100℃. In other words,
In this case, no matter how much electricity is consumed to heat the water, all that energy is simply lost to the latent heat of the water. Therefore, if the temperature is controlled at a temperature slightly lower than 100°C, the energy lost to latent heat will be minimized. Experimentally, it was best to keep the water temperature at around 97℃. By doing this, hot water can be supplied without boiling off excess water.

Further, it is easy to configure the predetermined temperature to be freely changed by an external setting signal.

Effects of the Invention As described above, according to the present invention, there is provided a temperature rise rate measuring means for measuring the temperature rise rate of water using the temperature detected by a temperature detector placed in contact with a container as an input signal;
It is equipped with a boiling detection means that detects the boiling point when the temperature increase rate becomes less than a predetermined value based only on the measurement means from the temperature increase rate measuring means, and boiling is detected only by a change in the temperature increase rate. As a result, excellent detection accuracy can be obtained without being affected by the type of container being heated, changes in atmospheric pressure, etc. Further, after the boiling point detected by the boiling detection means, a temperature comparator compares the temperature with a predetermined temperature slightly lower than the boiling temperature at the boiling point detected by the temperature detector, and the output of the temperature detector is used to determine the temperature of the heating element. The temperature is controlled to a predetermined temperature by controlling the supply of electricity, and since this predetermined temperature is slightly lower than the boiling temperature, it is possible to maintain an almost boiling state with a small amount of electric power.
Moreover, with this configuration, even if the hot water is not used immediately, it will not become cold, so if the predetermined temperature is set to the heat retention temperature, the water can be kept warm. Moreover, since the heating power is maximized until the boiling point is reached, the temperature rise time is also shortened, and various other excellent effects are achieved.

[Brief explanation of drawings]

Figure 1 is a plan view of a heating cooker showing an embodiment of the present invention, Figure 2 is a block diagram of the heating cooker, Figure 3 is an electric circuit diagram of the heating cooker, and Figure 4 is the heating cooker. It is a flowchart showing an example of a cooking device program. DESCRIPTION OF SYMBOLS 1... Heating element, 4... Container, 5... Temperature detector, 6... Temperature rise rate measuring means, 7... Boiling detection means, 8... Temperature comparator, 9... Heat generating element control means.

Claims (1)

[Claims] 1. A heating element that heats a container containing water, a temperature detector that is brought into contact with the container, and a temperature increase rate measuring means that measures the rate of temperature increase of the water using the temperature detected by the temperature detector as an input signal. and boiling detection means that detects the boiling point when the temperature rise rate becomes equal to or less than a predetermined value based only on the measurement signal from the temperature rise rate measuring means; and after the boiling point detected by the boiling detection means, the temperature A heating cooker comprising: a temperature comparator for comparing with a predetermined temperature slightly lower than the boiling temperature at the boiling point detected by the detector; and a heating element control means for controlling energization to the heating element based on the output of the temperature comparator.