JPS6367105B2 - - Google Patents

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.

Conventionally, when cooking stew or the like, it is necessary to initially heat the food with strong heat, then boil the contents over low heat for a long time. These operations are
Until now, people had to do it by hand, so there were many mistakes such as forgetting to turn off the heat even when it 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 boil. However, inserting a temperature sensor into a cooking pot to detect the temperature of the contents is inconvenient and creates an unsanitary 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 at the bottom of a pot and controls the heat. It is an object of the present invention to provide a cooking temperature control device that can be set independently. In order to achieve this objective, the cooking temperature control device of the present invention detects the slope of the temperature rise until the content of the simmering cooking boils, and depending on the degree of slope, the temperature control device detects the slope of the temperature rise until the contents of the simmering cooking boils. The sampling time for detection is changed to ensure accurate control to avoid erroneous detection of the bending point, no matter what the slope of the temperature rise.

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, and shows an example of a gas table stove. 1 is the gas inlet, and the gas is connected to the proportional control valve 2.
It passes through and burns in burner 3. Burner 3 is pot 4
The bottom of the container is heated to add heat to the contents of the cooked food 5. 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 sampling time determination section, a bending point detection section 9, and a proportional control section 10, and controls the combustion amount of the burner 3 by driving the proportional control valve 2.

In the conventional control method, the signal from the sensor 6' is directly transmitted to the proportional control section 1, as shown in FIG.
0', thereby outputting a drive signal for the proportional control valve 2'. That is, when the signal from the sensor 6' is lower than the set temperature of the proportional control section 10', the proportional control valve 2' is fully opened and the burner 3' is at maximum combustion. As the temperature of the sensor 6' increases and approaches the set temperature, the proportional control valve 2' gradually begins to throttle and the combustion amount 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 cooking It is difficult to correlate the temperature of object 5'. In particular, in stewing cooking, the timing to reduce the heat after boiling is when the temperature of the contents reaches 100℃, so if the temperature is set to exceed 100℃,
No matter how long it takes, the temperature of the contents will never reach the set temperature (because water does not rise above 100℃)
The proportional control valve 2' does not work and the fire power is not reduced.
On the other hand, if the set temperature is 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. A set temperature is 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, we focus on the fact that since the water does not reach a temperature of 100°C or higher, the temperature of the contents reaches 100°C, and if it does not rise any further, the temperature rise at the bottom of the pot will decrease, and detect the inflection point of the slope of the temperature at the bottom of the pot. The structure is as follows.

Figure 2 shows the temperature rise characteristics, and the horizontal axis X is time;
The vertical axis T indicates temperature, and the figure shows an example of the characteristics when water is boiled. AA' indicates the temperature of the contents, that is, the water temperature, and BB' indicates the temperature of the bottom of the pot, that is, the temperature detected by the temperature sensor 6. AB shown by the solid line has a large temperature rise, 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 temperature rise at A′B′ shown by the broken line For example, the pot 4 is small and contains a large amount of water, or the pot 4 is made of a material with poor heat conduction or is thick.

Temperature Ta is at room temperature and by heating, curve AB,
A′B′ both rise. The temperature BB' detected by the temperature sensor 6 has a rising curve that becomes gentle once at the temperature Tb, and then starts rising again from the temperature T. this is,
This is because dew condenses on the bottom of the pot at temperatures around Tb to T and further evaporates, and the temperature Tb to T is about 40 to 70°C, although it varies depending on the size and material of the pot 4. Furthermore, as the temperature continues to rise, the temperature Tc reaches 100°C, and the water temperature AA' boils and does not rise above 100°C.
At this time, the sensor temperature BB′ is Td, and Td is also the water temperature.
From the point where AA′ reaches 100°C, the rising characteristic becomes very small or disappears. This Tc point is 100℃ and
The temperature difference in Td varies greatly depending on the type of pot 4 (material and thickness) and the amount and type of food to be cooked. However, the inflection point CC′ where the slope of temperature rise changes is always the water temperature
This is after AA' has boiled.

FIG. 3 is a diagram showing inclination detection or bending point detection of sensor temperature B. In this method, the temperature change ΔT is measured every sampling time ΔX ₂ , and the bending point detection unit 9 determines that the point where ΔT becomes less than a certain value P is the bending point, and the temperature at that time is determined. Td
In this method, the temperature of the contents is set to 100℃. In addition to this method, the bending point detection unit 9 may also be configured to detect when the ratio of temperature rise becomes less than a certain value P, that is, T _o −T _o-1 /T _o-1 T _o-2 Constant value P
Let Td be the point below. The denominator of T _o-1 −T _o-2 may be the previous temperature, for example, T _o-5 −T _o-6 .

Here, the sampling time ΔX ₂ of the bending point detection unit 9 is _the temperature T at which the rising curve of the sensor temperature _B is stabilized _. =
It can be changed arbitrarily by T _D.
That is, as shown in FIG. 2, the slope detection unit 8 detects the slope of the rising curve of the sensor temperature B as a temperature slope T _D , and if the slope T _D is steep, the sampling time ΔX of the bending point detection unit 9 ₂ short, slanted
If T _D is gentle, the sampling time ΔX ₂ of the bending point detection unit 9 is changed in several stages according to the degree of inclination T _D of the inclination detection unit 8 so as to lengthen the sampling time.

The temperature 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 control valve 2 and stop combustion based on the signal from the bending point detector 9, and this method is most suitable for boiling water. Another example is a method in which the amount of combustion is reduced based on the signal from the bending point detection unit 9 to reduce the amount of calories and further heat the food.This method is generally suitable for stewing and can be simmered over a low heat over a long period of time.

Figure 4 shows this control characteristic, and the horizontal axis X is time;
The vertical axis T of the characteristic V is the temperature, the broken line A indicates the temperature of the contents as in FIG. 2, and the solid line B indicates 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 control valve 2, 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 control valve current I is at its maximum, and the combustion amount of the burner 3 is also at its maximum combustion. When the internal temperature reaches Tc point 100° C. at time Xd and boiling starts, the bending point detection section 9 detects this and sets the proportional control valve current I to the maximum value, narrowing down the combustion amount to the minimum combustion amount. At this time, the proportional control unit 10 adjusts the temperature Td to
The temperature is set as a set temperature, and the proportional control valve current I, that is, the combustion amount, is proportionally controlled according to the difference between the set temperature and the sensor temperature.

Now, if the food to be cooked is added at time Xe, 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. The proportional control section 10 increases the proportional control valve current I to Ie in accordance with the difference between the temperature Te and the set temperature Td. This results in
The amount of combustion also increases, and the temperature A returns to the original temperature Tc,
The combustion amount also returns to the minimum combustion amount. The size of Ie above is
It changes depending on the size of Td-Te; if Td-Te is large, Ie is large, and if Td-Te is small, Ie is
becomes smaller.

Furthermore, the inclination characteristic up to the bending point of the inclination detection section 8 is approximately proportional to the amount of contents. 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 characteristic will be gradual if the pot is made of a material with poor heat conductivity or is thick, and becomes steep if the pot is made of a thin material with good heat conduction.

Therefore, by varying the minimum aperture amount Id after detecting the bending point according to the inclination of the inclination detection section 8,
Even better cooking becomes 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 Id is also increased and set as Id'. On the other hand, if the slope is steep, the amount of combustion is small or the pot has good heat conduction, so the amount of combustion is reduced as Id''.

Also, as explained in Fig. 2, the temperature Tb~T
In order to prevent the bending point detection unit 9 from detecting bending due to bending due to No more mistakes.

Recently, microcomputers (hereinafter referred to as microcomputers) are often used to create complex control systems such as those described above. Figure 5 shows the first to
A simple flow diagram is shown in which the control system described in FIG. 4 is created using a microcomputer.

In FIG. 5, step 101IG is a subroutine of the ignition sequence for igniting the burner 3, steps 104, 115, 129S1 are a subroutine for reading the temperature S1 of the sensor 6, and step 13
1, S2 indicates a subroutine that determines the throttle amount of the proportional valve 2 according to the magnitude of the temperature difference Td - S1 between the set temperature Td and the sensor temperature S1, and outputs the control current _I. is a subroutine that outputs a signal to drive the proportional valve 2 to the maximum in order to achieve maximum combustion at the initial stage of ignition. Furthermore, F in steps 102, 107, and 109 is a binary flag for determining the early stage of combustion start, and F=0 in step 102 at the early stage of combustion start. After ignition (step 101), while the sensor temperature S1 is lower than the temperature Tf at which tilt detection starts, the loop of I in FIG. 5 is repeated, and in step 105, S1>Tf.
Wait until it becomes. If S1>Tf, the sensor temperature S1 at that time is stored in the memory T in step 106.
(P), and since the flag F is O,
At step 107, the program enters the loop shown in FIG. 5, passes through the subroutine ΔX ₁ to wait for a predetermined sampling time for inclination detection (step 108), switches flag F to 1 (step 109), and changes the sensor temperature again. S1 is measured.
Although not shown, the first memorized T(P)
The value of T measured this time after the sampling time has elapsed
The values of (P) are stored again in memories T(0) and T(1), respectively. Next, since the flag F=1,
Moving on to the inclination detection section shown in FIG. This inclination detection section calculates the inclination TD explained in FIG. 3 from T(1) and T(0) (step 110). is a portion of the bending point detection unit 9, which has a comparison unit The configuration is such that the time ΔX2 is determined to pre-stored values α, β, and γ (steps 112, 113, and 114), and thereafter the sensor temperature S1 is sampled at the time determined by the sampling time determination unit 8a (step 11).
5). Furthermore, the bending point detection section repeats the loop shown in FIG.
The value of T _(o-1) is stored in the two previous measurement values T _(o-2) (step 116), and the previous measurement value Tn is stored in the one previous measurement value T _(o-1). (Step 117), and further stores the current measurement value S1 in Tn (Step 118)
Repeat this operation in sequence. During this time, a temperature increase slope T _p is calculated (step 119), and this T _p is compared with a predetermined bending value P (step 12).
0) Repeat this until Tp<P holds. Here, T _p is calculated using the formula shown in FIG. 5, but various calculation methods such as simply comparing the temperature gradient Tn-T _(o-1) and the bending value P can be considered.

If Tp<P holds true, the routine shifts to the operation of the proportional control section 10. In this embodiment, the sampling time is determined so that the bending value P can be determined using a predetermined fixed value, but the bending value P may also be made variable along with the determination of the sampling time.

Here, the minimum combustion amount of the burner is varied according to the temperature gradient TD mentioned above.
The value of is compared with the three previously stored values of a, b, and c (step 122), and the proportional valve 2 is adjusted accordingly.
The minimum current value Id for driving is determined as Id', Id'' (steps 123 to 125) and output (step 126).Then, the stored temperature measurement value T _{(o-1 )} is stored as the set temperature Td (step 127), and the amount of heating is controlled in subroutine S2 of step 131 (step 130) according to this value and the value of sensor temperature S1 measured thereafter (step 129).Step 128 of
X _END is a determination unit for stopping the heating operation when the preset cooking time X ends. still,
The sampling time determination section may be tilted other than this configuration.
Various configurations are possible, such as a configuration in which the sampling time is determined by an arithmetic expression using TD as a variable.

As described above, the cooking temperature control device of the present invention measures the slope of the temperature rise of the sensor during simmering cooking, changes the sampling time according to the slope, and detects the bending point, thereby controlling the temperature of the food. Since the structure is configured to detect when the temperature of the food to be cooked and the sensor temperature is not constant, the boiling point can be accurately detected. That is, the temperature slope of the sensor temperature increase curve varies depending on the capacity of the pot and the type of pot (the material and thickness of the pot). If the slope is steep, even if the sampling time is short, the temperature rise per unit time will be large, so it will be possible to accurately capture the temperature rise.On the other hand, if the sampling time is long, the detection of the boiling point will be delayed, which may cause boiling over. I get used to it. If the slope is gentle, the temperature rise per unit time is small, and in order to prevent malfunction of detecting the bending point before the boiling point due to the influence of temperature fluctuations caused by convection inside the pot, the sampling time is This increases accuracy by increasing the length of the sensor and measuring changes in temperature rise. Therefore, the boiling detection range for stewing or cooking rice can be widely applied to boiling detection for simply boiling water.

In addition, the method for detecting inclinations and bending points is simple by determining the difference in sensor temperature through sampling at predetermined time intervals, making it easy to control with a microcomputer, etc., and allowing accurate bending point detection just by processing a program. The system can be configured to

Furthermore, the above-mentioned tilt detection 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, ensuring a stable and reliable tilt. can be detected, therefore, the inflection point (boiling point)
can be detected.

In addition, by having a proportional control section that proportionally controls the proportional valve using the sensor temperature at the bending point as the set temperature, once it has boiled, it can automatically switch to low heat and simmer while maintaining the temperature. If the temperature drops after adding such things,
The combustion amount 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 this embodiment, the proportional control type of a gas table stove was explained as an example, but an electric stove may be used, and the present invention can also be applied to an oven or the like in addition to a stove. Furthermore, instead of proportional control, high-low control or on/off control may be used.

In this way, depending on the slope of the sensor temperature,
By changing the sampling time to detect the bending point, the boiling point can be accurately detected regardless of the amount of food being cooked or the type of pot, and automation is achieved with optimal temperature control for simmering, making this cooker of great practical value. can be provided.

[Brief explanation of drawings]

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 slope FIG. 4 is a characteristic diagram illustrating the operation of the proportional control section after detection of the bending point. FIG. 5 is a characteristic diagram illustrating the state of detection and bending point detection. FIG. 6 is a schematic flow diagram showing an example of a case where the part) is configured by a microcomputer, and FIG. 6 is a control system diagram of a conventional proportional control system based on pan bottom temperature detection. 2... Proportional control valve (heating control means), 3... Burner (heating means), 5... Food to be cooked, 6... Temperature sensor (temperature detection means), 7... Temperature control section, 8...
...Tilt detection unit, 9...Bending point detection unit, T _D ...Degree of inclination, P...Bending value (value that corresponds to a predetermined bending point), C...Bending point, ΔX ₂ ... Sampling time, ...Sampling time determination section, X...Comparison section.

Claims (1)

[Claims] 1. A heating means for heating the food to be cooked, a temperature detection means for detecting the temperature of the food to be cooked, a heating control means for controlling the heating amount of the heating means, and a heating control means for controlling the temperature according to a signal from the temperature detection means. It has a temperature control unit that outputs a control signal, and the temperature control unit includes a slope detection unit that detects the temperature rise slope of the food to be cooked by the temperature detection means at each sampling time, and a temperature rise detected by the slope detection unit. a sampling time determining unit that corrects the sampling time so that if the slope is small, the sampling time is lengthened, and if the temperature rise slope is large, the sampling time is shortened;
It has a bending point detecting section that detects a bending point at which the temperature gradient of the tilt detecting section becomes equal to or less than a predetermined value at this sampling time after the sampling time is determined, and the heating means is controlled by a signal from the bending point detecting section. A cooking temperature control device that outputs a signal for varying or stopping the amount of heating from a temperature control means to a heating control means.