JPH033854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to cooking with a high moisture content, such as stewing, using a heating cooker such as a stove.
The present invention relates to a cooking temperature control device that can control the temperature of food to be cooked at a constant level with high precision.

BACKGROUND TECHNOLOGY Traditionally, stews and other stews require a procedure of heating with strong heat at the beginning, and then boiling the contents over low heat for a long time once the contents have boiled. Up until now, these operations had been done by hand, so there were many mistakes such as forgetting to turn down the heat even when the food was boiling, resulting in burnt food. Moreover, in this case, energy is wasted.

Therefore, an automatic control device that detects the temperature of the contents and automatically reduces the heat when the contents boil is being considered. However, inserting a temperature sensor into a cooking pot to detect the temperature of the contents is inconvenient and unsanitary. For this reason, a method has been developed in which a temperature sensor is brought into contact with the bottom of a cooking pot to detect the bottom temperature and to infer the temperature of the contents.

Problems to be Solved by the Invention However, this method has a drawback in that the temperature at the bottom of the pot and the temperature of the contents are not constant and vary depending on the material shape, thickness, amount of contents, etc. of the pot.

For example, as a conventional control means, the signal of the sensor 6 is directly introduced into the proportional control section 10 as shown in FIG.
As a result, there was a structure in which a drive signal for the proportional control section 2 was output.

FIG. 5 is a diagram of a control system for a gas table stove. Reference numeral 1 indicates a gas inlet, and gas passes through a proportional control valve 2 and is combusted in a burner 3. The burner 3 heats the bottom of the pot 4 and adds heat to the food 5 to be cooked. Reference numeral 6 denotes a temperature sensor that detects the bottom surface temperature of the pot 4, and this signal is input to the proportional control section 10 to drive the proportional control valve 2 and control the combustion amount of the burner 3.

With the above configuration, the signal from the sensor 6 is transmitted to the proportional control section 10.
When the temperature is lower than the set temperature, the proportional valve 2 is fully opened and the burner 3 is at maximum combustion. As the temperature of the sensor 6 rises and approaches the set temperature, the proportional valve 2 gradually begins to throttle and the amount of combustion is also throttled. When the temperature of the sensor 6 reaches the set temperature, the proportional valve 2 is throttled down to the minimum, and the burner 3 reaches the minimum combustion amount that allows safe combustion.

In this case, there is no problem as long as the correlation between the temperature of the sensor 6 and the temperature of the food 5 is constant. However, it is difficult to correlate the temperature of the sensor 6 and the temperature of the food 5 because the pot and the amount of cooking vary depending on the food being cooked.

Especially in stew dishes, the temperature at which the inside boils, that is, the timing to reduce the heat after boiling, is when the temperature of the contents reaches 100 degrees Celsius if the atmospheric pressure is 1 atm. When the set temperature is reached, the temperature of the contents will never reach the set temperature no matter how long it takes (water is 100°C at 1 atm).
2) Proportional valve 2 does not work and the firepower is not reduced. On the other hand, if the temperature is too low, the heat will be turned down before the temperature reaches 100°C, and subsequent heating will be done over low heat, so the temperature will not come to a boil easily, so a very precise temperature setting is required.
Furthermore, temperature control becomes impossible when considering the above-mentioned variations depending on the pot and the amount of food to be cooked.

In addition to this, if the boiling point of water changes, it becomes impossible to detect the boiling point using conventional control methods.

For example, when cooking with a pressure cooker, the internal pressure increases and the boiling temperature reaches 120-130°C, but it does not boil at 100°C. 100 at high altitudes with low atmospheric pressure.
It boils at temperatures below ℃, and the temperature does not rise to 100℃, causing boiling and burning. Similar problems arise even in a configuration in which the temperature sensor is inserted directly into the food being cooked.

Means for Solving the Problems In order to solve the above problems, the cooking temperature control device of the present invention includes a heating means for heating a food containing moisture contained in a container such as a pot, and a heating means for heating a food containing moisture contained in a container such as a pot. A temperature detection means for detecting the temperature of the container in contact with the container, and a temperature control section for outputting a control signal to the heating control means for controlling the heating amount of the heating means according to the signal of the temperature detection means, and the temperature control section has a temperature detection means for detecting the temperature of the container. , an inclination detection section that detects a temperature increase inclination of the container by the temperature detection means, and a time gradient of the temperature detected by the inclination detection section such that the increase in temperature of the food detected by the temperature detection means becomes gradual and is set to a predetermined value. It has a bending point detection section that detects the bending point below, and is configured to vary or stop the heating amount of the heating means based on the boiling detection signal of this bending point detection section. The device is configured to operate based on a signal from a tilt detection start section that detects when the signal reaches a predetermined measurement start temperature or higher.

Function The above configuration allows direct detection of changes in atmospheric pressure, sensor variations, or the temperature of the food when cooking food with a large amount of water, such as in simmering or boiling water. Even in the case where the food is not boiled, it has the effect of accurately detecting that the food has boiled, and at the same time has the effect of preventing malfunctions caused by detecting an unstable temperature slope at the initial stage of heating by the slope detection starting section.

Example The present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing a sequence of control systems to which the present invention is applied. This example shows an application to a gas table stove.

1 is a gas inlet, and gas passes through a proportional control valve 2 and is burned in a burner 3. The burner 3 heats the bottom of the pot 4 and adds heat to the food 5 to be cooked. 6 is a temperature sensor that detects the bottom surface temperature of the pot 4, and this signal is transmitted to the temperature control section 7. The temperature control section 7 includes an inclination detection section 8, a bending point detection section 9, and a proportional control section 1.
0 and drives the proportional control valve 2 to control the combustion amount of the burner 3.

The present invention focuses on the fact that when water boils at 1 atm, the temperature reaches 100°C and does not rise any further, and is configured to detect the slope of temperature rise.

Fig. 2 shows the temperature rise characteristics when using an aluminum pot with a thin wall pressure, where the horizontal axis X shows time and the vertical axis T shows temperature. The figure shows an example of the characteristics when boiling water. A shows the temperature of the contents, that is, the water temperature, and B shows the temperature of the bottom of the pot, that is, the temperature detected by the sensor 6. Temperature Ta increases in both curves A and B due to heating at room temperature, and at temperature Tb, the increasing curve once becomes gentle and starts to rise again. This is because the moisture condensed around the container evaporates at temperature Tb, and this temperature varies depending on the material and size of the container (pot), but is approximately 40 to
The temperature is 70℃.

As the temperature further increases, the temperature Tc reaches 100°C, and at one atmospheric pressure, the water temperature A boils and does not rise above 100°C. At this time, the temperature B of the sensor is Td, and since the water temperature A reaches 100° C., the rising characteristic of Td decreases or disappears. This Tc
The temperature difference between (100℃) and Td and the temperature gradient after the interior boils vary greatly depending on the material of the pot and the amount and type of food to be cooked. For example, the thicker the wall and the less heat conductive the pot, the greater the temperature difference between the inside and the sensor.
Even after boiling, the temperature at the bottom of the pot tends to gradually rise.

Also, if the pressure changes using a pressure cooker etc., the temperature will change.
Tc itself disappears at 100℃. However, the inflection point C where the slope of temperature rise changes is always the point where water boils.

FIG. 3 is a diagram showing an example of tilt detection or bending point detection. This method uses sampling time ΔX
The bending point detection unit 9 measures the temperature change ΔT at each
The point where ΔT becomes below a certain value is determined to be the inflection point, and the temperature Td at that time is the content temperature of 100℃.
There is a way to set the temperature to . At this time, the constant value for determining the bending point is a value determined after considering various conditions such as the material and shape of the pot, the thickness of the pot, the amount of food to be cooked, and the type of cooking. This value may be configured to be changed according to the above conditions, but as a means for not changing it, in the embodiment, a means for detecting that the ratio of temperature rise becomes below a certain level in the bending point detection section is used. There is. In other words, (Tn−Tn
− ₁ )/(Tn− ₁ −Tn− ₂ ) is below a certain value as Td. (This equation may be in any form as long as it determines the slope ratio.) The proportional control section 10 can shift to various types of control based on the signal from the bending point detection section 9. One possible method is to close the proportional valve 2 based on the signal from the bending point detector 9 to stop combustion. This is ideal for boiling water. Another example is a method of reducing the amount of combustion based on the signal from the bending point detection unit 9 and further heating with a small amount of calories. Generally, stews are cooked using the latter method, and are often simmered over low heat for a long time.

FIG. 4 shows this control characteristic, where the horizontal axis X is time, the vertical axis T of characteristic V is temperature, the broken line A is the temperature of the contents as in FIG. 2, and the solid line B is the temperature characteristic of the sensor at the bottom of the pot. The vertical axis I of the characteristic W indicates the control current of the proportional valve, which is proportional to the combustion amount of the burner 3. Until time Xd, before the signal from the bending point detection section 9 shown in FIG. 3 is output, the proportional valve current I is at its maximum, and the combustion amount of the burner 3 is also at its maximum combustion. At time Xd the internal temperature is Tc
(100°C) and starts boiling, the bending point detection unit 9 detects this and sets the proportional valve current I to the minimum value, narrowing down the combustion amount to the minimum combustion amount. At this time, the proportional control section 10 has the temperature Td set as the set temperature, and proportionally controls the proportional valve current, that is, the combustion amount, according to the difference between the set temperature and the sensor temperature. Now, if food is added at time Xe, the internal temperature A will decrease. Along with this, the temperature B of the sensor also decreases, and a decrease in the internal temperature A is detected. The proportional control section 10 controls this temperature Te.
The proportional valve current I is increased to Ie according to the difference between the temperature Td and the set temperature Td. As a result, the amount of combustion increases and the temperature A
returns to the original temperature Tc, and the amount of combustion also returns to the minimum amount of combustion. The size of Ie above changes depending on the size of Td−Te, and when Td−Te is large, Ie increases and Td−
If Te is small, Ie will be small.

The proportional control valve 2 may be an on-off valve or a multistage valve. At this time, the proportional control section 10 is configured to perform on/off control or multi-stage control operation.

In addition, as explained in FIG. 2, in order to prevent the bending point detecting part 9 from detecting the bending caused by the temperature Tb, the bending point detecting part 9 is set at the measurement starting temperature by the inclination detection starting part I.
The configuration operates from Tf or above, eliminating errors in detecting bending points due to unstable inclination detection.

Recently, microcomputers (hereinafter referred to as microcomputers) are often used to create complex control systems such as those described above. FIG. 6 shows a simple flow diagram when the control system described in FIGS. 1 to 4 is created using a microcomputer.

In Fig. 6, IG is a subroutine for the ignition sequence of the burner 3, S1 is a subroutine for reading the temperature Sl of the sensor 6, and S2 is a subroutine that determines the throttle amount of the proportional valve 2 according to the size of the temperature difference Td-Sl and controls the current I. Indicates the subroutine to output.

The temperature at which the post-ignition sensor temperature Sl is set higher than the unstable temperature Tb part explained in Figure 2.
Until Tf is reached, Sl>Tf goes through the loop shown in the figure.
Wait for it to become.

Start partial tilt detection when Sl>Tf. Here, the temperature Sl of the sensor 6 measured as explained in FIG. 3 is stored for each sampling time ΔX. In other words, when the temperature Sl of sensor 6 is measured, the memory of the sampling temperature two times before is erased and the temperature at the time of the first sampling is re-memorized as the temperature two times before (Tn- ₂ ←
Tn- ₁ ), the value measured during the previous sampling is re-stored as the previous temperature (Tn- ₁ ←Tn).
Furthermore, the temperature Sl measured this time is stored as the current value Tn (Tn←Sl). In this way, the configuration is such that the values in each memory are replaced at every sampling time.

is the calculation section of the bending point detection section, and Tp in the figure is a value determined by the following equation.

Tp = (Tn-Tn- ₁ ) / (Tn- ₁ - Tn- ₂ ) In other words, Tp is the difference between the current measurement value and the previous measurement value, and the difference between the first measurement value and the second measurement value. This means that we are looking for the ratio of the difference in values. Detection of bending points is
When the value of Tp becomes smaller than a predetermined value P, that is, the point at which the increase in each sampling temperature becomes smaller is determined to be the inflection point.

If the condition Tp<P is not satisfied, the next sampling time ΔT is measured and stored again in a loop.

After Tp<P and the bending point is detected, the process shifts to the loop shown in the figure and becomes proportional control. Here, the minimum throttle amount Id of the proportional control valve is set in three stages according to the temperature difference before detecting the bending point, that is, the difference between the first temperature and the second temperature (Tn- ₁ - Tn- ₂ ). (See Fig. 4, W). This is because if the slope is large, the amount of food cooked is small, so the minimum combustion amount is also reduced (Id''), which reduces the chance of burning the food.If the slope is small, the amount of food cooked is large.
This is for the purpose of increasing the minimum combustion amount (Id') and preventing it from cooling down. Furthermore, the proportional control section V stores the temperature Tn- ₁ of the sensor immediately before detecting the bending point as the set temperature Td, as explained in FIG. The throttle amount of the proportional valve 2 is determined by subroutine S2 so that the ratio becomes zero, and the proportional control valve is driven. In other words, if the temperature difference Td-Sl is large, the food being cooked is getting colder, so the combustion amount of the burner increases, and Td-Sl increases.
When becomes zero or a negative value, it is assumed that the food is sufficiently boiled, and the operation is performed to set the minimum squeezing amount Id.

XEND indicates a program that stops combustion of the burner when a preset cooking time X ends.

The effect of the above embodiment is that by configuring a proportional control section that proportionally controls the proportional valve using the temperature of the sensor at the bending point as the set temperature, once it boils, the temperature is maintained and the heat is automatically turned off to low. It is possible to perform simmering instead, and if the temperature drops due to the addition of additional ingredients, the amount of combustion will be automatically increased and the original temperature will be restored in a short time. Therefore, you can safely simmer and cook without any failures such as burning or boiling over, and you can save energy by preventing unnecessary heating.

Although the embodiment of the present invention has been described using a gas stove, similar effects can be obtained with other heaters such as an electric stove. Furthermore, it can be widely applied to cooking appliances such as kettles and rice cookers.

Effects of the Invention As explained above, the cooking temperature control device of the present invention has the following effects.

(1) Measuring the slope of the temperature rise of the food during simmering and detecting the inflection point where the value becomes smaller than a predetermined value to detect when the temperature of the food has reached the boiling point. Because of this configuration, even when the relationship between the temperature of the food being cooked and the temperature of the sensor is not constant, that is, there are variations in the sensor, and even when the temperature at the bottom of the pot is detected as in the example, the boiling point can be accurately determined even when the thickness or material of the pot changes. There is no need to worry about the temperature setting being low and the water being detected before it boils, or even if the setting temperature is high and the water is boiling, it will not be detected forever and the water will boil over or burn.
It is very easy to use and there are no cooking mistakes.

(2) Since the tilt detection starting section I does not perform tilt detection on a portion where the tilt is unstable due to dew condensation or the like in the early stage of heating, errors in tilt detection are small and malfunctions can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram showing one embodiment of the cooking temperature control device of the present invention, FIG. 2 is a characteristic diagram showing the sensor section of FIG. 1 and the rising state of internal temperature, and FIG.
The figure is a characteristic diagram explaining the state of inclination detection and bending point detection, Figure 4 is a characteristic diagram explaining the operation of the proportional control section after detecting the bending point, and Figure 5 is a conventional example of a proportional control system using pan bottom temperature detection. Control system diagram, No. 6
The figure is a schematic flow diagram showing an example of a case where the temperature control section (section 7 in FIG. 1) of the present invention is configured with a microcomputer. 2... Proportional control valve (heating control means), 3... Burner (heating means), 4... Pot (container), 5... Food to be cooked, 6... Sensor (temperature detection means), 7... Temperature control Part, 8... Tilt detection part, 9... Bend point detection part, 10... Proportional control part, I... Tilt detection start part, Td... Set temperature, Tf... Measurement start temperature, P
...predetermined value.

Claims (1)

[Claims] 1. A heating means for heating a food containing moisture contained in a container such as a pot; a temperature detection means for detecting the temperature of the container by contacting the outer bottom of the container; a temperature control unit that outputs a control signal to a heating control unit that controls the amount of heating of the unit; a bending point detection section for detecting a bending point at which the rise in temperature of the food detected by the food to be cooked becomes gradual and the time gradient of the temperature detected by the slope detection section becomes equal to or less than a predetermined value; The heating amount of the heating means is varied or stopped according to the boiling detection signal of the temperature detecting means, and the tilt detecting section is configured to detect when the detection signal of the temperature detecting means becomes equal to or higher than a predetermined measurement start temperature. A cooking temperature control device that operates based on a signal from the start section.