JPH0221004B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating cooker that maintains the temperature of the food at a constant level by continuously varying the amount of heating, and particularly when there is a large difference between the temperature of the food and the set temperature. An object of the present invention is to provide a control device configured to shorten the time it takes for the temperature to reach a set temperature.

Conventionally, automatic temperature control type cookers have been developed for reasons such as automation of cooking, safety, and energy saving. Figure 4 shows an example of application to a gas table stove. In this example, the temperature at the bottom of pot 1 is detected by temperature sensor 2, and the comparison amplification circuit 3 compares and amplifies it with the set temperature 4 to continuously vary the gas amount. The proportional valve 5 is driven. Thereby, the combustion amount of the burner 6 is controlled to a value according to the temperature sensor 2 and the set temperature 4. 7 indicates a manual source.

FIG. 5 shows its operating characteristics, and the horizontal axis D shows the temperature, and the vertical axis L shows the combustion amount of the burner 6. If the temperature of temperature sensor 2 is sufficiently lower than the set value 4, the combustion amount is the maximum combustion amount L ₁ of the burner (X in the diagram).
area). As the temperature of the temperature sensor rises, the proportional valve 5 is gradually throttled down and the combustion amount decreases (range Y in the figure).Next, when the sensor temperature reaches the set temperature _D1 , the combustion amount decreases to L. ₂ , which is set to the minimum combustion amount that allows burner 6 to burn safely. Therefore, even if the temperature rises further, the proportional valve 5 will not be throttled down and will maintain the combustion amount _L2 (range Z in the figure). In addition to this, when setting the temperature set value D ₁ to the middle point of the Y range, etc.
There is also a method that turns the valve on and off in the Z region.

Temperature sensor 2 when food is added to pot 1
As the temperature decreases, the amount of combustion moves along the characteristic line in FIG. 5 and increases. As described above, the combustion amount is increased or decreased to maintain the temperature at the bottom of the pot constant.

This time chart is shown in FIG. 6 and FIG. 7, where the horizontal axis T shows time, the vertical axis D shows temperature, and L shows the amount of combustion.
Further, characteristic A in the figure shows the case where the proportional control shown in FIG. 4 is performed, and characteristic B shows the characteristic when the burner 6 is always at maximum combustion without performing the control.

Now, if burner 6 is ignited at time _TO , the burner burns at its maximum in area X in Figure 5 until the temperature rises and reaches time _T1 , and characteristics A and B do not change.
Next, when the Y range is reached, as shown in FIG. 7, characteristic A starts to reduce the combustion amount and reaches the set temperature at time _T2 .
At this time, as shown in FIG. 6, since the combustion amount is not reduced in characteristic B, the temperature reaches the temperature D ₁ determined at time T ₂ ', but the temperature continues to rise. In this case characteristic A
is held at a temperature D ₁ . Further, at time _T3 , the temperature of the temperature sensor 2 decreases by adding food to be cooked, but in this case, characteristic A operates to immediately increase the combustion amount and return to the set temperature _D1 . However, characteristic B
After the temperature drops once, it will rise further.

As can be seen from the above, characteristic A takes a longer time to reach the set temperature than characteristic B. This occurs because the combustion amount is reduced as the temperature of the temperature sensor approaches the set temperature.

Furthermore, if the food inside the pot 1 is a stewed dish with a lot of water, the set temperature _D1 needs to be 100°C. At this time, even if the temperature rises above 100℃ due to variations in the set temperature, the internal temperature will never rise above 100℃ (because water boils at 100℃).
Therefore, the set temperature will not be reached forever, so the amount of combustion will not be reduced and there is a risk of burning.
For this reason, if the temperature was set lower than 100°C for safety reasons, the amount of combustion would be reduced quickly, which would take a long time to reach the set temperature, which would be inconvenient for cooking.

The present invention has a configuration in which if the difference between the set temperature and the temperature of the temperature sensor exceeds a certain level, heating is performed at the maximum combustion rate until the set temperature is reached, and then proportional control is performed, thereby making it possible to shorten the delay in the rise time. .

Embodiments of the present invention will be described below with reference to the drawings.
Reference numeral 8 in FIG. 1 indicates a memory circuit, in which the difference between the temperature of the temperature sensor 2 and the set temperature 4 is stored in a predetermined first memory circuit.
If the set value is 9 or more, a drive signal is output to the holding circuit 10. The holding circuit 10 outputs a signal to the comparator amplifier 3 that maintains the maximum combustion amount of the burner 6 regardless of the temperature of the temperature sensor 2. Furthermore, the memory circuit 8 outputs a signal to the holding circuit 10 to release the holding when the temperature of the temperature sensor becomes equal to the set temperature, and the proportional valve 5 controls the burner combustion amount according to the difference between the temperature of the temperature sensor 2 and the set temperature. to control. Reference numeral 11 indicates a controller including the above circuit.

Figure 2 shows its operating characteristics, and the horizontal axis D represents temperature.
The combustion amount is shown on the vertical axis _L1 . The characteristic shown by the solid line in the figure is the proportional control characteristic similar to that shown in FIG. temperature here
D ₁ - D ₂ corresponds to a predetermined first set value 9, and when the temperature of the temperature sensor 2 falls below D ₂ , the memory circuit 8 stores this, and the holding circuit 10 sets the maximum combustion amount. hold. Therefore, even in the Y range, heating is continued with the maximum combustion amount as shown by the broken line in the figure. When the sensor temperature reaches the set temperature _D1 , the holding circuit 10 is released and normal proportional control characteristics (solid line)
Return to

FIG. 3 shows a concrete example of the circuit. Reference numeral 12 is a DC power supply which supplies power to the controller through a switch 13 interlocked with the switch 7.

Temperature sensor 2 (example using negative temperature sensitive resistance element), temperature setting variable resistor 4 and resistor 14,
15 and 16 constitute a bridge circuit, the midpoint potential a is connected to the negative input terminal of the operational amplifier 18 through the resistor 17, and 6 is connected to the positive input terminal.
The operational amplifier 18 constitutes an inverting amplifier circuit with resistors 17 and 19, and its output is connected to the base of a transistor 21 through a resistor 20.
The emitter of transistor 21 is connected to the negative input terminal of operational amplifier 18 through resistor 19 and to the line of power supply 12 through resistor 22, respectively. In addition, the collector of the transistor 26 is connected to the proportional valve 5.
It is connected to the line of the power supply 12 through.
Here, the proportional valve 5 is shown as an example using an electromagnetic gas proportional control valve configured to continuously vary the gas flow rate in accordance with the current flowing through the electromagnetic coil. 23 is proportional valve 5
protection diode for absorbing the back electromotive force of the coil, 24
represents the base resistance of the transistor 21.

Here, the current value I flowing through the proportional valve 5 is determined by the following equation.

I={b-R19/R17(a-b)}/R22 (A) From the above, if the temperature of sensor 2 is low, sensor 2
has a large resistance value, and therefore the potential a becomes low.
According to the above formula, I at this time increases. Conversely, when the temperature of the sensor 2 is high, the potential a increases and the potential I decreases. When the potential a=b, it indicates that the sensor temperature has reached the set temperature. Here, if the setting variable resistor 4 is increased, the resistance of the sensor 2 will be reduced by the increase in the variable resistor in order to make the potential a=b, which corresponds to an increase in the set temperature by that amount.

The potential a is also connected to the negative input terminal of the operational amplifier 25, and the positive input terminal is connected to the divided potential c of resistors 26 and 27, and is also connected to the output terminal through a resistor 28 and a diode 29.
Furthermore, the output terminal of the operational amplifier 25 is a diode 30.
It is connected to the positive input terminal of operational amplifier 18 through. Since the operational amplifier 25 operates as a comparator, it will be referred to as a comparator hereinafter. When the comparator 25 has a high output, that is, when the diode 29 is reverse biased, the resistors 26 and 27 are connected so that the potential b=c.
is being designed. Further, when the output of the comparator 25 is low, the potential c is connected in parallel with the resistor 17 and the resistor 28 and the diode 29, so that the potential b>c', forming a predetermined first set value 7.

At the beginning of energization, the temperature of the temperature sensor 2 is low and the potential a<
c', the comparator 25 has a high output. This state is stored until the potentials a=b=c, that is, the temperature sensor 2 reaches the set temperature. Further, since the output of the comparator 25 becomes high (approximately the same as the potential of the power supply), the potential b also goes high through the diode 30, and the output of the amplifier 18 outputs a high output regardless of the potential a. Therefore, the transistor 21 becomes completely conductive and the proportional valve 5 is maintained at the maximum combustion amount. When the temperature sensor 2 reaches the set temperature (a=c), the comparator 25 has a low output and the diode 30 is reverse biased, so the current I is controlled to a value according to the potential difference between the potentials a and b.

Furthermore, even if the temperature drops due to adding material to pot 1 during control, the temperature drop is small and the potential a>
If c', the comparator 25 does not invert and continues normal proportional operation. Also, the temperature drop is large and the potential a<
c', the current I is held at the maximum value as at the time of rise.

FIG. 8 shows another embodiment. This is especially true when cooking by stewing, etc. as there is a lot of moisture inside the food.
If the temperature exceeds 100℃, the temperature will not rise because it will boil, and if there is even a slight variation in the set temperature than 100℃, the set temperature will not be reached forever and the combustion will continue, so there is a risk of burning. be. This can be solved by setting the set temperature a little lower in advance, but in this case, once the set temperature is reached, the amount of combustion reaches the minimum, so the temperature does not rise any further and the contents do not boil.

Therefore, in FIGS. 8 and 9, when the memory circuit 8 is operating, the holding circuit 10 is held at the maximum combustion amount in the Y region, and when the set temperature D ₁ is reached, the holding circuit 10 is held at the maximum combustion amount. The control amount L2 is switched to ₃ and held in that state. In this state, when the temperature of the temperature sensor exceeds a predetermined second set value 31 (D ₃ -D ₁ ), the memory circuit 8 releases the holding state of the holding circuit 10 . With the above configuration, even if the set temperature D ₁ is set slightly lower than 100°C, heating will continue at the combustion amount L ₃ until a certain temperature rise occurs even after the set temperature D ₁ is reached. The rise time is shorter than when the combustion amount is suddenly reduced to _L2 .

FIG. 10 shows an example of this specific circuit.

The potential c divided by the resistors 26, 32, and 33 is applied when the outputs of the operational amplifier 34 and the comparator 25, which operate as comparators, are high outputs (the diode 2
9 and 35 are reverse biased), the potential is b=c. At the beginning of ignition of the burner 6, the temperature of the temperature sensor 2 is low, so the potential a is the resistance 32,
33, the resistor 28 and the diode 29 are connected in parallel to the potential d', and the comparator 25 becomes a high output and stores this. At this time, the comparator 25 maintains the current I of the proportional valve 5 at the maximum current as in FIG. When the temperature of the temperature sensor 2 rises and reaches the set temperature (potential a = c), the output of the comparator 34 becomes low and the output of the amplifier 18 is divided by the resistors 20 and 20' through the resistor 36 and the diode 37. lowers the potential of At this time, the amplifier 18 is connected to the comparator 2.
5 outputs an output that supplies the maximum current to the proportional valve, but is biased by the resistor 36 to maintain the current value of the proportional valve at the second value.

As the temperature of the temperature sensor further increases, the potential a
When ≧d (D ₃ in FIG. 9), the comparator 25 becomes a low output and reverse biases the diode 30 to cancel the memory. As a result, the negative input terminal of the comparator 34 also becomes a low potential through the diode 38, so the comparator 34 becomes a high output and the diode 37
Let be the reverse bias. From the above, the proportional valve 5 has a potential a
The combustion amount is controlled according to the difference between and b. 39 is a positive feedback resistor for stabilizing the operation of the comparator 34.

In this way, after the set temperature is reached, a circuit is provided that switches the value held at a predetermined combustion amount between the maximum combustion amount and the minimum combustion amount until the temperature rises further by a predetermined amount. By setting the set temperature to a low value considering various variations, it is especially possible to cook ingredients with high moisture content such as stewing.
When setting the temperature to 100°C, the set temperature will not be reached no matter how long it takes due to variations in the high-temperature side of the set temperature, which eliminates the risk of burning the food by heating with strong combustion.

In this embodiment, a gas burner is used as the heating device, but an electric heater or the like may also be used. It can also be applied to things other than table stoves. Furthermore, although the embodiment has been described using a gas proportional control valve as the control means, the same effect can be obtained by using a multi-stage control valve (a controller including a plurality of valves may also be used).

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

(1) When continuously controlling the amount of heating, the purpose of this is to prevent the heating power from being reduced as the temperature approaches the set temperature.
Since the holding circuit is configured to operate when heating starts or when the temperature drops significantly below the set temperature, the time required to reach the set temperature can be shortened, saving cooking time while releasing nutrients and flavor. This will also improve your cooking performance.

(2) Similarly, since the holding circuit is configured to deactivate when the set temperature is reached, once the set temperature is reached, normal fine-grained control is achieved and the food is maintained at a constant temperature. There is no temperature drop due to burning or heat radiation.

[Brief explanation of drawings]

Fig. 1 is a control system diagram of the control device for the heating cooker of the present invention, Fig. 2 is its characteristic diagram, Fig. 3 is its specific circuit diagram, Fig. 4 is a control system diagram of the conventional proportional control circuit, and Fig. 5 6 and 7 are time charts at the start of combustion of the system in FIG. 4, FIG. 8 is a control system diagram showing another embodiment of the present invention, and FIG. 9 is its characteristic diagram. , FIG. 10 is a specific circuit diagram thereof. 2... Temperature sensor (temperature detector), 3... Comparative amplifier, 4... Temperature setting value (temperature setting means), 5
... Proportional valve (control means), 6 ... Burner (heating means), 8 ... Memory circuit, 9 ... Predetermined first setting value, 10 ... Holding circuit, 11 ... Controller, 32 ... ...predetermined second setting value.

Claims (1)

[Scope of Claims] 1. A heating means for heating a food to be cooked, a temperature sensor for detecting the temperature of the food to be cooked, and a heating amount of the heating means to be continuously or multiplied according to a signal from the temperature sensor. a controller that compares and processes a signal from the temperature sensor and a signal from the temperature setting means to supply a signal to the control means to maintain the temperature of the food to be cooked at a constant temperature; a memory circuit that stores the difference between the temperature signal detected by the temperature sensor and the temperature setting means when it exceeds a predetermined first set value; and a drive amount of the control means based on the output of the memory circuit. The heating cooking is configured to drive a holding circuit that holds the temperature constant, and the storage circuit is configured to release the driving of the holding circuit when the temperature signal detected by the temperature detector becomes equal to the set temperature of the temperature setting means. device control device. 2 The holding circuit is configured to switch the control means to hold the second driving amount when the temperature signal detected by the temperature detector and the set temperature of the temperature setting means become equal, and the storage circuit is configured to switch the control means to the second driving amount when the temperature signal detected by the temperature detector becomes equal to the set temperature of the temperature setting means. The control of the heating cooker according to claim 1 is configured to release the drive of the holding circuit when the temperature signal exceeds a predetermined second set value than the set temperature of the temperature setting means. Device.