JPH022054B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides that when cooking with a high moisture content such as stewing or boiling water using a heating cooker such as a stove, the temperature of the food reaches the boiling point (100°C). This invention relates to a cooking temperature control device that can detect temperature accurately.

Traditionally, stews and other stews require the initial step of bringing the contents to a boil over high heat, then reducing the heat to low and simmering for a long time. Until now, this operation had been done by hand, which resulted in many failures such as forgetting to turn off the heat while the food was boiling, resulting in burnt food. Or, even when boiling water, it often happens that the water continues to heat up without even realizing it has boiled, causing it to boil over. This makes the food useless and wastes energy. Furthermore, if the water boils over, there is a risk of burns and the like, and in the case of a gas stove, for example, it may cause a gas leakage accident due to a misfire, which is extremely dangerous.

Therefore, automatic control devices are being considered that detect the temperature of the contents and notify you when the contents boil, extinguish the fire, or automatically reduce the firepower. However, inserting a temperature sensor into a cooking pot or the like to detect the temperature of the contents is not convenient and feels unclean. For this reason, a method has been devised in which a temperature sensor is brought into contact with the bottom of the cooking pot to detect the bottom temperature of the pot and from this the temperature of the contents can be estimated by analogy. However, with this method, 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, and capacity of the pot, so it is extremely difficult to detect the point at which the temperature of the contents reaches 100℃. It was difficult.

The present invention is a cooking temperature control device that detects the temperature at the bottom of a pot, and can reliably detect the temperature regardless of the material of the pot or the amount of contents, especially when controlling the internal temperature to 100 degrees Celsius when there is a lot of moisture, such as when boiling or boiling water. The purpose of this invention is to provide a cooking temperature control device that can control cooking temperatures.

In order to achieve the above object, the cooking temperature control device of the present invention is configured to detect the slope of temperature rise until the contents boil, and detect the boiling point according to the slope.

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

FIG. 1 is a diagram showing an example of a control system 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.

If the conventional control method is used, the signal from the sensor 6 is directly introduced into the proportional control section 10 as shown in FIG.
As a result, a drive signal for the proportional control valve 2 is output.
In other words, when the signal from the sensor 6 is lower than the set temperature of the proportional control section 10, the proportional valve 2 is fully opened and the burner 3
is the maximum combustion. As the temperature of the sensor 6 rises and approaches the set temperature, the proportional valve 2 gradually begins to throttle down and the amount of combustion is also throttled down. 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, since the pot and the amount of cooking vary depending on the food to be cooked, it is difficult to determine the correlation between the temperature of the sensor 6 and the temperature of the food 5.

Especially in stew dishes, the timing to boil and reduce the heat is when the temperature of the contents reaches 100℃, so if you set the temperature so that the contents reach 100℃ or higher, the temperature of the contents will change no matter how long it takes. does not reach the set temperature (because water does not rise above 100°C), 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 from then on the food will have to be heated on low heat, so it won't come to a simmer, so a very precise temperature setting is required. In addition to this, temperature control becomes impossible when considering the above-mentioned variations depending on the pot and the amount of food to be cooked.

Therefore, in the present invention, we focused on the fact that since the water does not reach a temperature higher than 100°C, the temperature of the contents reaches 100°C, and if the temperature does not rise any further, the temperature rise at the bottom of the pot will decrease, and we have created a configuration that detects the slope of the temperature at the bottom of the pot. .

For this purpose, as shown in FIG.
The slope of the temperature rise is detected by the slope detection section 8, and the bending point where the slope value ΔT becomes equal to or less than the predetermined bending value Tu is detected by the bending point detecting section 9. At this point, it is determined that the food has boiled. Thereafter, the proportional control valve 2 is driven by the proportional control section 10 to perform temperature control.

FIG. 2 shows temperature rise characteristics, where the horizontal axis X represents time, and the vertical axis T represents 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 on both curves A and B due to heating at room temperature, and at temperature Tb, the increasing curve once becomes gentle and begins to rise again. This is because the moisture condensed around the container evaporates at temperature Tb.
This temperature varies depending on the material and size of the container (pot), but is approximately 40 to 70°C.

As the temperature further increases, the temperature Tc reaches 100°C, and 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 becomes very small or disappears. This Tc (100℃)
The temperature difference between and Td varies greatly depending on the material of the pot and the amount and type of food being cooked. However, the inflection point C where the slope of the temperature rise changes is always the point where the water temperature A 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℃.
This is a method to set the temperature to . In addition to this method, the bending point detection section may also detect when the ratio of temperature rise falls below a certain value.

Here, as shown in FIG. 4, the bending characteristics during boiling vary greatly depending on the amount of food to be cooked. For example, when the amount of cooking is small, the slope of temperature rise is steep as in the M characteristic, and the slope becomes almost zero at the boiling point. However, when the amount of cooking is large, the slope is very gentle as in the N characteristic, and the slope gradually becomes smaller even at the boiling point.
From the above, it is difficult to simply determine if the slope is below a certain value. Therefore, the temperature rise TW at a fixed time interval △XA is measured at a point Tf that exceeds the Tb point in Figure 2, and the bending point detection section compares the temperature rise TW with △T according to the measured value.
Tu has configuration fixes. Here the constant value is
It is calculated using a formula that uses Tw as a function.

Tu=k・Tw+L However, when the slope changes greatly as shown in Figure 4, the range of change in △T in Figure 3 is very large. Especially when the slope is gentle, the slope △T at a short sampling time △X is very large. The value becomes small, making it difficult to accurately detect the inclination. On the other hand, if the sampling time ΔX is long when the slope is steep, there is a risk that boiling detection will be delayed and the water will blow out. Therefore, in the present invention, the sampling time is switched depending on the value of the initial slope Tw. In this example, the value of Tw is greater than the constant value Tv.
In the case of Tw′, the amount of cooking is small and the temperature rise is rapid, so the sampling time is short △X′, and the bending point detection is △T (temperature rise during sampling time △X′) ≦K′・TW′＋L ′ On the other hand, when Tw is smaller than Tv, the amount of cooking is large and the temperature rise is slow, so the sampling time is a long time △X″, and the bending point detection is △T (temperature rise during sampling time △X″) ≦ K″・TW″＋L″. Here, it branches into two points depending on whether Tw is larger or smaller than Tv, but it may be three or more points, and the more branches there are, the higher the accuracy will be.

Therefore, as shown in FIG. 1, the slope of the temperature rise when the temperature rises above a predetermined sensor temperature Tf is measured by the initial slope detection section, and this initial slope is compared with the pre-stored slope value Tv and the comparison section V. Compare by
In accordance with this result, the calculation unit calculates and obtains the bending value Tu for determining the bending point by the bending point detection unit 9. Here, the value Tv compared in the comparison section is
It is also possible to have a plurality of values and compare the respective values, and vary the calculation method based on the results.

Further, in FIG. 1, the sampling time ΔX for subsequently detecting the slope of temperature rise by the slope detection unit 8 based on the result of the initial slope detection unit is configured to be varied by the sampling time determination unit.

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 a signal from the bending point detection section 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. 5 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 becomes large and Td-te
When is small, Ie becomes small.

Further, as explained in FIG. 2, the bending point detection section 9 is configured to operate from the measurement start temperature Tf or higher so that the bending point detection section 9 does not detect bending due to the temperature Tb, thereby eliminating errors in detecting the bending point.

Recently, microcomputers (hereinafter referred to as microcomputers) are often used to create complex control systems such as those described above. A simple flow diagram is shown in which the control system described in FIGS. 7 to 5 is created using a microcomputer.

In the figure, IG is the ignition sequence subroutine for igniting burner 3, and S1 is the temperature of sensor 6.
S1 is a subroutine that reads S1, and S2 is a subroutine that determines the throttle amount of the proportional valve 2 according to the size of the temperature difference (Td - S1) between the set temperature Td and the sensor temperature S1, and outputs the control _current I. The OUT section outputs a signal that drives the proportional valve 2 to the maximum in order to achieve maximum combustion at the beginning of ignition, and F is a binary flag for determining that the initial slope has been detected. =0. After ignition, sensor temperature
As long as S1 is lower than the temperature Tf at which tilt detection starts in Figure 2, loop I in the figure is repeated, and S1>Tf
Wait for it to become.

When S1>Tf, the initial inclination Tw explained in the figure is detected in the routine of the initial inclination detection section. In the initial slope detection section, _S1A is a temperature sensor whose temperature S1 is set to 2 at intervals of sampling time ΔX _A after exceeding the start temperature Tf in order to measure the initial slope.
This is a memory for determining whether the temperature sensor has been measured twice. Immediately after exceeding Tf, S _1A = 0, so the value S1 of the temperature sensor is stored in S _1A . After the next ΔX _A has elapsed, since S _1A ≠0, the initial slope Tw is calculated from S _1A and the sensor temperature S1 measured this time.

Thereafter, the determination unit V compares the initial slope Tw with a previously stored determination value Tv, thereby changing the conditions for determining the bending point. This condition is to select the calculation constants K and L for calculating the comparison value for determining the bending point according to the initial slope Tw and, if necessary, the sampling time ΔX for detecting the slope in the sampling time determination section. . Here, the configuration is such that the determination unit V branches into two, but the invention is not limited to this, and the bending point can be detected with higher accuracy as the number of branches increases. Here, the determination flag F=1.

Next, a bending value Tu for determining the bending point is calculated by the calculation unit using the constants determined in these routines.

Thereafter, the process passes through a subroutine that calculates the temperature rise ΔT during the sampling time ΔX, and moves to a slope comparison section that compares this ΔT with the comparison value Tu.
Here, until ΔT<Tu holds true, the comparison is repeated at every sampling time ΔX. At this time, since the flag F=1, the initial inclination detection section and the bending value calculation section are not passed through again.

If ΔT<Tu holds true in the slope comparison section, that point is determined to be a bending point, the sensor temperature S1 at that time is stored as the set temperature Td, and the operation moves to a comparison control loop.

In the proportional control loop, the amount of heating is controlled in subroutine S2 according to the set temperature Td and the value of the sensor temperature S1 measured thereafter, and the amount of heating is controlled so that the sensor temperature S1 maintains the set temperature Td. For this reason, once the food boils, it is controlled to continue boiling. In addition to this, it is also possible to have a configuration that stops heating or forcibly reduces the heat when the boiling point occurs, and this can be changed depending on the type of cooking.

X _END is a determination unit for stopping the heating operation when the preset cooking time X ends.

As explained above, the cooking temperature control device of the present invention measures the slope of the temperature rise of the food during simmering, etc., and detects the bending point to determine whether the temperature of the food has reached the boiling point. Since the configuration detects the boiling point, it is possible to accurately detect the boiling point even if the relationship between the temperature of the food to be cooked and the temperature of the sensor changes.

In addition, by configuring the slope detection method to obtain the difference in sensor temperature through sampling at predetermined intervals, control using a microcomputer, etc. is easy, and accurate boiling point detection can be performed simply by processing a program, making it extremely simple. The system can be configured to

Furthermore, the configuration is such that the bending point comparison value is calculated according to the value of the initial slope Tw, and by branching the calculation constant into multiple stages and switching the sampling time of the bending point comparison value, it is possible to achieve higher accuracy and a wider range. Therefore, it is possible to accurately detect a range from a small amount (about 200 c.c.) to a large amount (about 6 cc).

In addition, since the initial inclination Tw is configured to be measured at the point where the sensor temperature reaches a predetermined value (approximately 70 to 80 degrees Celsius) or higher, it ignores temperature fluctuations caused by condensation on the bottom of the pot in the early stages of combustion. Boiling can be detected reliably.

In this way, the boiling point can be detected regardless of the material and shape of the pot or the amount of food to be cooked, and there is no risk of misfire due to boiling over, making it safe and saving energy from wasted overboiling.

Finally, as explained in the examples, it is particularly effective to apply a temperature sensor to a cooker configured to detect the temperature of the bottom of the pot containing food, and it is possible to Errors caused by the amount of food, etc. are eliminated, and optimal stewing cooking is possible.

As mentioned above, we believe that it has great industrial value and has many effects.

In this embodiment, the proportional control type of a gas staple stove was explained as an example, but it can also be applied to an oven or the like in addition to an electric stove. Furthermore, instead of proportional control, high/low control, on/off control, etc. may be used.

[Brief explanation of drawings]

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 showing the difference in the rising state of sensor temperature depending on the amount of food to be cooked, and Figure 5 is a characteristic diagram of the proportional control section after detecting the bending point. A characteristic diagram explaining the operation, Fig. 6 is a control system diagram of a proportional control system using pan bottom temperature detection in a conventional example, and Fig. 7 shows a case where the temperature control section of the present invention (section 7 in Fig. 1) is configured with a microcomputer. FIG. 2 is a schematic flow diagram showing an example. 2...Proportional control valve (heating control means), 3...Burner (heating means), 5...Cooked food, 6...Temperature sensor, 7...Temperature control section, 8...Inclination detection section,... Initial inclination detection section, 9, ...Bending point detection section, ...Sampling time determination section, V...Comparison section, ...Calculation section, ...Inclination comparison section, Tf...
...Measurement start temperature, Tu...Bending value, Tw...Tilting output of initial tilt detection section, ΔT...Tilting value, ΔX...
...sampling time.

Claims (1)

[Scope of Claims] 1. A means for heating a food to be cooked, a temperature sensor for detecting the temperature of the food to be cooked, and a control signal sent to a heating control means for controlling the heating amount of the heating means in accordance with a signal from the temperature sensor. The temperature control section includes a slope detection section that detects a temperature rise slope of the food to be cooked by the temperature sensor, and a bending value at which the temperature rise slope detected by the slope detection section is determined in advance. The means for heating the food has a bending point detecting section that detects a bending point at which the food is heated. an initial inclination detection section that measures and stores the inclination; a comparison section that compares the inclination output of the initial inclination detection section with a plurality of predetermined inclination values; and an arithmetic expression stored in advance according to the output of the comparison section. The configuration includes a calculation unit that calculates the bending value using the output of the initial inclination detection unit as a function, and a signal for varying or stopping the heating amount of the heating unit is sent from the temperature control unit to control the heating based on a signal from the bending point detection unit. A cooking temperature control device configured to output an output to a means. 2. The temperature control section has a sampling time determination section that selects a sampling time for measuring the inclination of the inclination detection section for determining the bending point according to the output of the comparison section from among pre-stored values. A cooking temperature control device according to claim 1.