JPS5862432A - Controller for temperature for cooking - Google Patents

Abstract

PURPOSE:To control temperature accurately regardless of the kinds of pans and the quantity of cooking by detecting the temperature-rise gradient of a material to be cooked and the point of bending where a temperature gradient reaches a predetermined value or lower. CONSTITUTION:The detecting signals of a temperature sensor 6 set up to the bottom of the pan 4 heating a material to be cooked 5 are tramsmitted to a temperature control section 7, and a proportional control valve 2 is controlled. In the temperature control section 7, a temperature change DELTAT at every sampling time DELTAX is measured in a gradient detecting section 8, a point where the temperature change DELTAT reaches a prescribed value P or lower is judged as the point of bending in a bending-point detecting section 9, a temperature where the temperatue of content reaches 100 deg.C at a temperature Td at that time is obtained, and the temperature is outputted to a proportional control section 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of cooking that makes it possible to accurately control the temperature of food to be cooked using a heating cooker such as a stove when cooking with a high content of water such as stewing. The present invention relates to a temperature control device for use.

Traditionally, when cooking stews such as shichi, it is necessary to initially heat the food with strong heat, and then boil the contents over low heat for a long time. 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 is being considered that detects the temperature of the contents and automatically reduces the heat when the contents reach a boil. However, inserting a temperature sensor into a cooking pot to detect the temperature of the contents is inconvenient and gives a dirty and dirty feeling. For this reason, a method has been devised in which a temperature sensor is brought into contact with the bottom of a cooking pot to detect the bottom temperature of the pot and to infer the temperature of the contents. However, this method has the disadvantage that the temperature at the bottom of the pot and the temperature of the contents are not constant and vary depending on the material, thickness, shape, amount of contents, etc. of the pot.

The present invention is a cooking temperature control device that detects the temperature of the bottom of a pot.
To provide a cooking temperature control device that can be set to 0° C. regardless of the type of pot or the amount of contents. In order to achieve this objective, the cooking temperature control device of the present invention detects the slope of temperature rise until the content of the simmering cooking boils, and depending on the degree of slope, the temperature rise bending point (100
By changing the detection value (the point at which the boiling point of water in °C do.

FIG. 1 is a diagram showing an example of a control system to which the present invention is applied, and shows an example of a gas staple stove. 1 is
At the gas inlet, the 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. 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 and a bending point detection section 9 inside.
, a proportional control section 1o, which drives the proportional control valve 2 to control the combustion amount of the burner 3.

Here, in the conventional control method, as shown in FIG. 7, the signal from the sensor 6' is directly input to the proportional control section 1σ, thereby outputting a drive signal for the proportional control valve 2'. When the signal from the sensor σ is lower than the set temperature of the proportional control section 1σ, the proportional control 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 control 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 control 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 if the correlation between the temperature of the sensor 6' and the temperature of the food 5' is constant, but since the type of pot and the amount of cooking vary depending on the food, the sensor 6' and the temperature of the food 5' vary. ′ is difficult to correlate with temperature. especially,
In stewing cooking, the timing to boil and reduce the heat is when the temperature of the contents reaches 100℃, so 100℃
If the set temperature exceeds ℃, the temperature of the contents will never reach the set temperature (water has a temperature of 10
Since the temperature does not rise above 0°C, the proportional control valve 2' does not work and the fire power is not reduced. On the other hand, if the temperature is set lower than 100℃, the heat will be turned off before the temperature of the contents reaches 100℃, and the contents will have to be heated over low heat, making it difficult for the contents to come to a boil. Temperature required. In addition to this, temperature control becomes extremely difficult when considering the aforementioned variations depending on the type of pot and the amount of food to be cooked. Note that 1' and 4' are the gas inlet and the pot, as in Fig. 1. Therefore, in the present invention, since the water does not reach a temperature of 100°C or higher, the contents reach 100°C and do not rise any higher. We focused on the fact that if the temperature at the bottom of the pot stops rising, the rise in temperature at the bottom of the pot will decrease, so we designed the system to detect the inflection point of the slope of the temperature at the bottom of the pot.

Figure 2 shows the temperature rise characteristics, the horizontal axis X shows time and the vertical axis T shows temperature.The figure shows an example of the characteristics when boiling water.
indicates the temperature of the contents, that is, the water temperature, and B and B' indicate the temperature of the bottom of the pot, that is, the temperature detected by the temperature sensor 6. A and B indicated by solid lines are cases where the temperature rise is large, for example, the amount of water is small, or the pot 4 is made of a material with good heat conductivity and is thin, and the cases A/ and B/ indicated by broken lines are The temperature rise is small, for example, if the amount of water is large, or if the pot 4 is made of a material with poor heat conductivity or is thick.

Curves A and B are obtained by heating the temperature Ta at room temperature.

Both A/ and B1 will rise. For the temperatures B and B' detected by the temperature sensor 6, the rising curve becomes gentle once at the temperature Tb, and then starts to rise again from the temperature Tf. This is because dew condenses on the bottom of the pan at temperatures around Tb and Tf, and then evaporates.
-Tf is approximately 40-70°C.

Furthermore, the temperature continues to rise and the temperature Tc is 100°C,
Water temperatures A and A' boil and do not rise above 100°C. At this time, the sensor temperatures B and B' are Td, and the water temperature A and A' are 100° C., so the rising characteristic becomes very small or disappears. This Tc point 100
The temperature difference between °C and Td varies greatly depending on the type of pot 4 (material and thickness) and the amount and type of food to be cooked. '
After it has boiled.

FIG. 3 is a diagram showing an example of inclination detection or bending point detection of sensor temperature B. This method uses sampling time △X
The bending point detection unit 9 measures the temperature change ΔT for each
This is a method in which the point where T becomes below a certain value P is determined to be the inflection point, and the temperature Td at that time is set as the temperature at which the content temperature becomes 100°C. In addition to this, the bending point detection unit 9
A method of detecting when the ratio of temperature rise becomes less than a certain value P can also be considered.
The point at which Tn-2) becomes equal to or less than a certain value P is defined as Td.
The denominator is the previous temperature, for example (Tn-5"n-6)
But that's fine. This bending value P can be arbitrarily changed by changing the temperature slope (T1-T0=TD) at the sampling time ΔX at a temperature Tf at which the rising curve of the sensor temperature B is stable, for example 80°C. Note that the sampling time Δx of the inclination detection section 8 and the bending point detection section 9 may not be the same.

The temperature control section 10 can shift to various types of control based on the signal from the bending point detection section 9. As an example, the bending point detection unit 9
One possible method is to close the proportional control valve 2 and stop combustion in response to the signal, and this is most suitable for boiling water. Another example is a method that uses the signal from the bending point detection unit 9 to reduce the amount of combustion and further heat the food with a small amount of calories, which is generally suitable for simmering and can be simmered over low heat over a long period of time. The horizontal axis or time indicates the control characteristics, and the characteristics V
The vertical axis T of is the temperature, the broken line A is the temperature of the contents as in FIG. 2, and the solid line B is the sensor temperature characteristic of the bottom of the pot. The vertical axis of the characteristic W indicates the proportional control valve 20 controlled spiritual flow, and the stiffness is proportional to the combustion amount of the burner 3.

Until time Xd, the proportional control valve current is at its maximum before the signal from the bending point detector 9 shown in FIG.
The amount of combustion is also the maximum combustion. At time Xd, the internal temperature is Tc
When the temperature reaches a point (100° C.) and boiling begins, the bending point detection unit 9 detects this and sets the proportional control valve current to the minimum value, narrowing down the combustion amount to the minimum combustion amount. At this time, the temperature Td is set as a set temperature in the proportional control section 10, and the proportional control valve current, that is, the combustion amount, is proportionally controlled in accordance with the difference between the set temperature and the sensor temperature. Now, if the food to be cooked is added at time Xθ, the content temperature A will decrease. Along with this, the sensor temperature B also decreases, and a decrease in the content temperature A is detected. Proportional control section 1
0 increases the proportional control valve current I to Is according to the difference between the temperature To and the set temperature Td. As a result, the combustion amount also increases, the temperature A returns to the original temperature Tc, and the combustion amount also returns to the minimum combustion amount. The magnitude of the above Ie changes depending on the magnitude of (Td-To); if (Td-To) is large, Is will be large, and if (Td-To) is small, Is will be small by 0.

Furthermore, the inclination characteristic up to the bending point of the inclination detection part 8 is proportional to the amount of the contents of the container. In other words, if the amount is large, the slope will be gentle; if the amount is small, the slope will be steep. In addition, the gradient characteristics will be gentler if the pot is made of a material with poor thermal conductivity or is thick, and steeper if the material is thin and has good thermal conductivity.

Therefore, by varying the minimum squeeze amount Id after the bending point is detected according to the inclination of the inclination detection section 8, even better cooking is possible. For example, if the slope is gentle, the amount of burnt is large or the pot has poor heat conduction, so the combustion amount 1d is also increased to be Id'. On the other hand, if the slope is steep, the amount of combustion is reduced as Id" because the amount is small or the pot has good heat conduction.

In addition, as explained in FIG. 2, in order to prevent the bending point detecting unit 9 from detecting bending due to temperature (Tb to Tf), the bending point detecting unit 9 is set at a temperature equal to or higher than the measurement start temperature Tf (a temperature at which the temperature rise is stable). ) will eliminate bending point detection errors.

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 flowchart when the control system described in FIGS. 1 to 4 is created using a microcomputer.

In the figure, IQ indicates the subroutine of the ignition sequence of the burner 3, Fba○ or 1, and Sl indicates the temperature S1 of the sensor 6.
S2 is a subroutine that determines the aperture view of the proportional valve 2 according to the magnitude of the temperature difference (Td-81) and outputs the electric current. After ignition, if the sensor temperature S1 is lower than Tf, the process goes through the loop I in the figure and goes through S1')
Wait for Tf. S 1) If T f, then F
The inclination TD explained in FIG. 3 is detected in the section marked ■ in the figure after passing through the loop marked ■ in the figure -1. ■ is the bending point detection section 9
The above-mentioned Tn-Tn-MeTn-
1''n-2 indicates 'rp and is compared with the bending value P.

If Tp is not smaller than P, the sampling time ΔX
Measure and construct the loop shown in ■.

- Tp<P, and after detecting the bending point, the process shifts to loop (3) and becomes the proportional control section 1o. Here, ■ is the part where the minimum combustion amount is varied according to the temperature gradient TD mentioned above, and TD is a
, b, and c indicate a program that stops operating when a preset cooking time X ends. The bending point detection unit (■) in Fig. 5 shows an example in which the bending value P is determined steplessly by multiplying the slope TD of (■) by a certain constant K. Fig. 6 shows another example. Indicated by ■, the slope TD branches at three points a, b, and a, and the bending value P is α, β.
.

It is divided into three stages of γ, and the others are controlled in the same way as in FIG.

As described above, the cooking temperature control device of the present invention measures the slope of the temperature rise of the food during simmering, changes the bending value according to the slope, and detects the bending point. Since the structure detects when the temperature of the food reaches the boiling point, it is possible to accurately detect the boiling point even if the relationship between the temperature of the food and the sensor temperature is not constant. In other words, the temperature slope of the sensor temperature increase curve varies depending on the capacity of the pot, the type of pot, and the material and thickness of the pot. The values will be different. For example, if the slope is gentle, the bending value will be large and the denominator will be small because the slope is gentle.

The steeper the slope, the smaller the bending value. Therefore,
By changing the bending value steplessly or in several steps depending on the degree of inclination, the boiling point can be detected accurately. In particular, erroneous detection of objects with a gentle slope can be eliminated.

In addition, the method for detecting inclinations and bending points is to obtain the difference in sensor temperature by sampling at fixed time intervals, which makes it easy to control with a microcomputer, etc., and allows accurate bending point detection just by processing a program. This makes it easy to configure the system.Furthermore, the detection of the tilt starts from the point where the sensor temperature reaches a predetermined temperature or higher, so that even if there is tilt fluctuation due to water condensing on the bottom of the pot during the initial heating stage, it is ignored. Therefore, it is possible to detect the slope stably and reliably, and therefore the bending point (boiling point) can be detected.

In addition, by having a proportional control section that proportionally controls the ratio 4 side valve using the sensor temperature at the bending point as the set temperature, once it boils, it is possible to automatically switch to low heat and simmer while maintaining that temperature. If the temperature drops due to the addition of additional materials, the amount of combustion is automatically increased and the original temperature is 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.

Furthermore, by adjusting the minimum amount of combustion after boiling according to the inclination of the inclination detection part, fine-grained simmering cooking can be achieved by adjusting the amount of heating depending on the amount of cooking contents and the type of pot. .

In addition, in this page 41-J, the proportional control type of a gas staple stove was explained as an example, but an electric stove may also be used.
It can be applied to open stoves as well as stoves. moreover,
Instead of proportional control, high-low control or on-off control may be used.

In this way, by changing the curvature value that detects the curvature point according to the degree of inclination of the sensor temperature, the boiling point can be accurately detected regardless of the amount of food being cooked or the type of pot. Automation is achieved with optimal temperature control, making it possible to provide a cooking device with great practical value.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram showing one embodiment of the cooking temperature controller of the present invention, Fig. 2 is a characteristic diagram showing the correlation between the sensor temperature in Fig. 1 and the internal temperature, and Fig. 3 is a diagram showing the correlation between the sensor temperature in Fig. 1 and the internal temperature. FIG. 4 is a characteristic diagram illustrating the bending point detection state. FIG. 6 is a characteristic diagram explaining the operation of the proportional control section after the bending point is detected. A schematic flowchart showing an example of a configuration using a microcomputer; FIG. 6 is a schematic flowchart of a microcomputer showing another embodiment of the bending point detection section (■) in FIG. 5; FIG. A diagram of a proportional control system based on detection is shown. 2... Proportional control valve (heating control means), 3...
・Burner (heating means), 6...Cooked food, 6...
...Temperature sensor (temperature detection means), 7...
Temperature control section, 8... Tilt detection section, 9...
・Bending point detection part, T...Inclination degree, P...
...bending value (value that becomes a predetermined bending point), K...
... Certain constant, JP-A-58-G2432C5-) C... Name of the inflection point agent Patent attorney Toshio Nakao and one other person 11
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Claims (4)

[Claims] (1) A heating means that heats the food, a temperature detection means that detects the temperature of the food, and a temperature control section that outputs a control signal to the heating control means that controls the heating amount of the heating means according to the signal from the temperature detection means. The temperature control section includes a slope detection section that detects a temperature increase slope of the food to be cooked by the temperature detection means, and a bending point detection section that detects a bending point where the temperature slope becomes less than or equal to a predetermined value. The heating amount of the heating means is varied or stopped according to a signal from the bending point detection section, and the bending point of the bending point detection section is determined according to the degree of inclination of the inclination detection section of the temperature control section. A cooking temperature control device that changes the value. (2) If the degree of inclination in the inclination detection section is dog, the value that becomes the bending point of the bending point detection section is set small, and if the degree of inclination is small,
Claim 1 in which the value of the bending point is increased.
Cooking temperature control device as described in . (3) A certain constant (6
2. The cooking temperature control device according to claim 1, wherein the value that becomes the bending point of the bending point detection unit is controlled steplessly by multiplying by . (4) The cooking temperature control device according to claim 1, wherein the value of the bending point of the bending point detecting section is divided into several stages depending on the degree of inclination at the inclination detecting section.