JPS58123026A - Temperature controller for cooking purpose - Google Patents

Abstract

PURPOSE:To exactly detect the boiling points regardless of the content or a cooking pan by using a system in which the gradient of temperature rise up to the boiling of the content of the pan is detected and based upon the detected value, the boiling point is detected in a controller to control the cooking temperature by detecting the temperature of the pan bottom. CONSTITUTION:The bottom of a pan 4 is heated by a burner 3 and the content 5 to be cooked is heated for cooking. In this case, a temperature sensor 6 for the bottom of the pan is provided and the detected output is put in the gradient detector 8 of a temperature detector 7. In the detector 8, the gradient of temperature rise of the content to be cooked is detected by the temperature sensor 6, the output is given to a knee point detector 9 where a knee point (a point at which a boiling point of 100 deg.C of water is obtained) below a predetermined value of temperature gradient is detected, a proportional control valve 2 is driven through a proportional controller 10 when the knee point is detected, and the combustion amount of the burner 3 is controlled. By this, regardless of the kinds of pans and the amounts of the contents, boiling points can be exactly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for preventing the temperature of the food from reaching the boiling point (100°C) when cooking with a high amount of water such as stewing or boiling water using a heating cooker such as a stove. This invention relates to a cooking temperature control device that can detect temperature accurately.

Traditionally, stewed dishes such as couchu require the initial step of bringing the contents to a boil over high heat, then lowering the heat to low and simmering for a long time. There were many mistakes where people forgot to turn down the heat and the food got burnt.

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 it boils over, there is a risk of burns, and in the case of a gas stove, it is extremely dangerous as it may cause a gas leak accident due to a misfire.

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 overall temperature of the contents can be estimated. However, with this method, the temperature at the bottom of the pot and the temperature of the contents are not constant;
It was extremely difficult to detect the point at which the temperature of the contents reached 100°C because it varied depending on the thickness and capacity of the contents.

The present invention is a cooking temperature control device that detects the temperature of the bottom of a pot, especially when boiling or boiling water, the internal temperature is 'i'.
To provide a cooking temperature control device that can reliably detect cooking temperature control at 100° C. regardless of the material of the pot or the contents.

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 according 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 staple stove.

1 is a gas inlet, and the 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 cooks the contents 6.
adding heat to. 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 7vC. The temperature control section 7 has an inclination detection section 8 and a bending point detection section 9 inside.
, a proportional control section 1°, which drives a proportional control valve 2 to control the combustion amount of the burner 3.

Here, if the conventional control method is used, the sensor 6
is directly introduced into the proportional control section 10, thereby outputting a drive signal for the proportional control valve 2.

In other words, when the signal from the sensor 6 is lower than the set temperature of the proportional control section 1o, 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 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 becomes 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 6 is constant. However, since the pot and the amount of cooking vary depending on the food being cooked, it is difficult to establish a correlation between the temperature of the cooker 6 and the temperature of the food 5. Especially when cooking stews, the timing of boiling and reducing the heat is determined by the temperature of the contents. This is when the temperature reaches 100°C, so when the set temperature is set so that the contents are over 100'C,
No matter how much time passes, the temperature of the contents never reaches the set temperature (because water does not rise above 100°C), the proportional valve 2 does not work, and the firepower is never reduced. On the other hand, if it is low, the temperature is 10
Very precise temperature settings are required, as the heat is turned down before the temperature reaches 0°C and the food is then heated over low heat, so it does not come to a boil. In addition to this, considering the above-mentioned variations depending on the pot and the amount of food to be cooked, temperature control becomes impossible. Therefore, in the present invention, since the water does not reach a temperature of 100°C or higher, the contents should not exceed 100°C. We focused on the fact that if the temperature at the bottom of the pot stopped rising, the temperature at the bottom of the pot would rise less, so we designed the system to detect the slope of the temperature at the bottom of the pot.

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, where M indicates the temperature of the contents and the water temperature, and B indicates the temperature detected by the temperature sensor 6 at the bottom of the pot. Temperature Ta increases both cycarpum and B by heating at room temperature, and at temperature Tb, the increasing curve becomes gentler and starts to increase 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 (pan), but is approximately 4.
The temperature is 0 to 70°C.

As the temperature further increases, the temperature Tc reaches 100°C, and the water temperature boils and does not rise above 100°C. The temperature B of the sensor at this time is Td, and Td also has a water temperature of 10
From the point where it reaches 0'C, the rising characteristic becomes very small, or
Or it will disappear. The temperature difference between Tc (100°C) and Td varies greatly depending on the material of the pot and the amount of food to be cooked. However, the inflection point C where the slope of temperature rise changes is always the point where the water temperature boils.

FIG. 3 is a diagram showing an example of tilt detection or bending point detection. This method is based on the temperature change 4 for each sampling time ΔX.
The bending point detection unit 9 determines that the point where ΔT becomes less than a certain value is the bending point, and detects the temperature Td at that time.
This is a method in which the content temperature approaches 100°C.

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 texture of the food. For example, when the amount of cooking is small, the slope of temperature rise is steep as in the V 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, at a point Tf that exceeds point Tb in Fig. 2, a certain time interval △
The temperature rise TV of Xmu is measured, and the fixed value Tu to be compared with ΔT is corrected in the bending point detection section according to the measured value. Here, the constant value is determined by a calculation formula using Tw as a function.

Tu= -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 becomes 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 according to the initial slope TwO value. In this example, the value of Tw is larger than the constant value Tma7w/
In the case of , the amount of cooking is small and the temperature rise is rapid, so the sampling time is set to △X' for a short time, and the bending point detection is set to △T (temperature rise during sampling time △X') ≦'・T
W + L' On the other hand, when Tw is smaller than Ty //, the amount of cooking is large and the temperature rise is slow, so the sampling time is long △X //, and the bending point detection is △T (sampling time △X" temperature rise)≦K //・Tw”+
Here, it branches to two points depending on whether Tw is larger or smaller than Ty, but it may be three or more points, and the more branches there are, the higher the accuracy becomes.

The proportional control section 1o can shift to various types of control based on the signal from the bending point detection section 9. An example of this is a method in which the proportional valve 2 is closed using a signal from the bending inspection detail 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 detector 9 and further heating with a small amount of calories.Generally, the latter method is used for simmering dishes. It is 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 M 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, the proportional valve current I is at its maximum before the signal from the bending point detection unit 9 shown in FIG.
The amount of combustion is also the maximum combustion. At time X (l, the internal temperature is T
c (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 unit 10 controls the temperature. T (1 is set as the set temperature, and the proportional valve current, that is, the combustion amount, is proportionally controlled according to the difference between the set temperature and the sensor temperature. Now, if food is added at time Xs, the internal temperature M will decrease. .

Along with this, the temperature B of the sensor also decreases, and a decrease in the internal temperature M is detected. The proportional control unit 1o increases the proportional valve current I to Is according to the difference between this temperature Te and the set temperature TdO.

As a result, the amount of combustion increases, the temperature returns to the expected temperature Tc, and the amount of combustion returns to the minimum amount of combustion. The magnitude of Is changes according to the magnitude of T(!-Te; if T(1-Te is large, Ie is thick; if Td-Te is small, Ie is small.

Further, as explained in FIG. 2, the bending point detection section 9 is configured to operate from the measurement start temperature Tf or above 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 6 is created using a microcomputer.

In the figure, IG is the Sara 1 routine of the ignition sequence of burner 3, Sl is the subroutine for reading the temperature S1 of sensor 6, and S
1 indicates a subroutine that determines the throttle amount of the proportional valve 2 according to the magnitude of the temperature difference Td-81 and outputs the current flow.

If the temperature S1 of the sensor after ignition is lower than Tf in FIG. 2, it passes through the loop I in the figure and waits until it reaches S, )Tf.

S, )Tf, the initial slope Tw explained in FIG. 2 is detected in the part (■).

■ is the bending point detection part, and the initial slope Tw [according to the calculation constant K
It includes a branching section V including v IL P and a time interval correction section ■, a calculation section ■ that calculates a comparison value Tu, and a slope comparison section ■ that compares Tu with the temperature rise ΔT between the time interval ΔX. . (3) is a proportional control loop, where the sensor temperature S1 at the time of detection of the bending point is set as the set temperature T(1), and from then on, an output corresponding to the temperature difference between T(i and the sensor temperature S1) is output to the proportional valve by 82.XICND indicates a program that stops operating when the preset cooking time X ends.
is written in the slope comparison part that compares the slope values, but this is the ratio of the slope values, that is, the slope comparison part may also be 0 or F.
indicates the detection flag of the initial inclination Tw, and after the initial inclination is detected, F
= 1, and thereafter the V·■ loop is bypassed.

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, the method of detecting inclination is configured to calculate the difference in sensor temperature by sampling at predetermined time intervals, making it easy to control with a microcomputer, etc., and it is possible to accurately detect boiling points just by processing a program, making the system very simple. can be configured.

Furthermore, the structure is such that the bending point comparison value is calculated according to the initial slope TwO value, and by branching the calculation constant into multiple stages and switching the sampling time of the bending point comparison value, high accuracy and wide range are achieved. Small amount (about 2ooCC)
It is possible to accurately detect a range from a large amount (approximately 6ff) to a large amount (approximately 6ff).

In addition, the initial slope Tw is determined by the temperature of the sensor being a predetermined value (
Since the configuration is such that measurement is performed at the point where the temperature reaches approximately 70-so'c) or higher, boiling can be detected reliably because the temperature flaking caused by condensation on the bottom of the pot in the early stages of combustion is ignored.

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, especially the temperature sensor,
It has a great effect when applied to a cooker that detects the temperature of the bottom of the pot containing food, and it can be used to detect the temperature of the pot's material, wall thickness, etc.
Errors caused by the amount of food to be cooked are eliminated, allowing optimal stewing cooking.

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

Although the present embodiment has been explained using the proportional system m type gas staple stove as an example, it can also be applied to an electric stove or the like. 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 rising state of the sensor section and internal temperature of Fig. 1, and Fig. 3 is an inclination A characteristic diagram explaining the detection state of the bending point in the detection unit, Fig. 4 is a characteristic diagram showing the difference in the rising state of the sensor temperature depending on the amount of food to be cooked, and Fig. 6 explains the operation of the proportional control unit after the bending point is detected. FIG. 6 is a conventional control system diagram of a proportional control system using pan bottom temperature detection, and FIG. 7 is an example of the temperature control section of the present invention (section 7 in FIG. 1) configured with a microcomputer. 1 is a schematic flow diagram illustrating. 2... Proportional control valve (heating control means), 3...
... Burner (heating means), 6 ... Food to be cooked, 6 ... Temperature sensor, 7 ... Temperature control section, 8. ■...Inclination detection section, 9. ■・・・・・・
・Bending point detection section, ■・River... Time interval correction section, ■...
...branch section, V (...calculation section, ■...
・Inclination comparison section, Tf-...Measurement start temperature, Tu...
...Bending point comparison value (predetermined value), Tw...
...Initial slope, △T...Temperature slope, △X・
...Temperature ramp time interval. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure Xd X Figure 4 111 × Figure 5 X Figure 6

Claims (4)

[Claims] (1) Outputting a control signal to a means for heating a food to be cooked, a temperature sensor for detecting the temperature of the food to be cooked, and 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 unit includes a slope detection unit that detects a temperature rise slope of the food to be cooked by the temperature sensor, and a temperature slope detected by the slope detection unit such that the temperature slope becomes equal to or less than a predetermined value. It has a bending point detection section that detects a bending point, and a branching section that branches into a plurality of parts according to the initial inclination detected by the inclination detecting section; A cooking temperature control device comprising a calculation section that calculates the predetermined value intermittently based on the value of the slope, and configured to vary or stop the heating amount of the heating means based on a signal from the bending point detection section. (2) The cooking temperature control device according to claim 1, further comprising a bending point detection section and a slope comparison section that compares a temperature gradient at constant time intervals with a predetermined value. (3) The cooking temperature control device according to claim 1, wherein the bending point detection unit includes a slope comparison unit that compares a ratio of temperature slopes at fixed time intervals with a predetermined value. (4) The time interval of the temperature gradient compared at the bending point detection section is
The cooking temperature control device according to claim 1 or 3, further comprising a time interval correction section that corrects the time interval according to the branched conditions at the branching section. (@ The cooking temperature control device according to claim 1, wherein the initial temperature gradient is measured after the means for heating the food starts heating and after the temperature sensor detects the measurement start temperature.