JPH0626642A - Controlling device for heating temperature of liquid for cooking - Google Patents

Abstract

PURPOSE:To enable the accurate temperature control of a liquid medium by carrying out the ON/OFF control of heating based on a liquid temperature and its temperature gradient. CONSTITUTION:A temperature of a liquid medium for cooking heated by a heating means (e.g. a pulse burner) 20 is detected by a temperature sensor 11, and the temperature gradient of the liquid medium is also detected. As a result, the temperature of the liquid medium is controlled by a controller 40 so that the pulse burner 20 is turned OFF at a temperature corresponding to the degree of a temperature increase before the heating of a material to be cooked reaches an upper limit value in a preset temperature range when the temperature gradient has an incresing tendency and so that the pulse burner 20 is turned ON at a temperature corresponding to the degree of a temperature decrease before the heating reaches a lower limit value in a preset temperature range when the temperature gradient has a decreasing tendency. By this method, such overshooting that a temperature of the liquid medium exceeds a preset temperature range can be avoided, and the accurate temperature control of the liquid medium can be carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooking liquid heating temperature control device. More specifically, it relates to cooking utensils for heating and cooking an object to be cooked through a liquid medium such as oil or boiling water. The present invention relates to a cooking liquid heating temperature control device for performing heating and temperature control of a liquid medium so as to be maintained within a certain temperature range.

[0002]

2. Description of the Related Art Conventionally, in cooking utensils and the like for cooking food to be cooked in a liquid medium (so-called "fried food", "boiled noodles", etc.), explosive combustion such as a pulse combustor is used as a heating device. There is a case where only the on or off (combustion stop) by repeating the above is used and there is no partial (low heat) state. In such a case, it is necessary to maintain the desired liquid temperature by the on / off control of the heating device. There is.

In that case, the conventionally generally known temperature control has a liquid temperature detector (for example, a thermistor, thermocouple, etc.), and as shown in FIG. 3, the detected liquid temperature is the upper limit of a desired temperature range. When the heating off temperature set to a temperature slightly lower than the value is reached, heating is turned off (finished), and when the detected liquid temperature falls to the heating on temperature set to a temperature slightly higher than the lower limit of the desired temperature range. The heating is turned on (started).

The reason for providing a slight temperature difference between the upper limit of the temperature range and the heating-off temperature is that the heat exchanger has a finite heat capacity and the liquid temperature is uniform due to convection of the liquid medium. This is because there is a time lag between when the heating is turned off and when the detected liquid temperature actually starts to drop. The reason why the lower limit of the temperature range does not match the heating ON temperature is the same. For this reason, the heating on-temperature and the off-temperature are set in consideration of the temperature change overshoot in a desired temperature range.

[0005]

However, in the temperature control of such cooking utensils, the overshoot of temperature change is not always constant. The overshoot changes due to deterioration of the liquid (tempura oil or the like in this case) or change in specific heat due to inclusion of foreign matter, and decrease in heat capacity of the liquid due to removal of liquid during cooking. Further, when a material having a large temperature difference from the liquid medium enters, such as when a new food item is introduced, a large temperature gradient is temporarily generated as shown by an arrow C in FIG. In that case, the overshoot becomes large.

In the conventional temperature control, the heating on-temperature and the off-temperature are fixed to preset values, and in particular, the setting is made in consideration of the overshoot in the state where no food is cooked. There was a problem that the liquid temperature greatly deviated from the temperature range when a new food item was added. Here, this problem can be alleviated by setting a small difference between the heating on temperature and the off temperature, that is, by setting a large overshoot. However, in that case, since the number of times the combustor is turned on and off is significantly increased, there is a disadvantage that the durability of the control circuit and the ignition circuit deteriorates.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to obtain a more accurate result based on the liquid temperature, the temperature gradient, and the on / off determination result of the heating device. An object of the present invention is to provide a cooking liquid heating temperature control device capable of controlling the temperature of a liquid medium.

[0008]

To achieve this object, a cooking liquid heating temperature control device of the present invention comprises heating means for heating a cooking liquid medium for heating and cooking an object to be cooked.
Liquid temperature detecting means for detecting the temperature of the liquid medium heated by the heating means, temperature gradient detecting means for detecting the temperature gradient of the liquid medium detected by the liquid temperature detecting means, and the detected temperature gradient When the temperature rises, the heating means is turned off at a temperature according to the temperature rise degree before reaching the upper limit of the temperature setting range of the liquid medium, and when the temperature gradient tends to decrease, The gist of the present invention is to provide temperature control means for turning on the heating means at a temperature according to the degree of temperature decrease before reaching the lower limit of the heating set temperature range.

[0009]

According to the temperature control device of the present invention having the above-mentioned structure, the object to be cooked is put into the liquid medium for cooking which is heated by the heating means, and the object to be cooked is cooked by the liquid medium. However, the temperature of the liquid medium is detected by the liquid temperature detecting means, and the temperature gradient of the liquid medium is detected by the temperature gradient detecting means. As a result, when the temperature gradient tends to rise, the heating means is turned off at a temperature according to the temperature rise degree before reaching the upper limit value of the heating setting temperature range of the food to be cooked, and the temperature gradient tends to fall. The temperature control means controls the temperature of the liquid medium so that the heating means is turned on at a temperature according to the temperature decrease degree before reaching the lower limit of the heating set temperature range. This prevents the liquid medium temperature from exceeding the set temperature range and overshooting.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the temperature control device of the present invention is embodied in a cooking utensil will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of the configuration of a cooking utensil equipped with the temperature control device of the present invention. The cooking utensil is a fryer for cooking (frying) fried chicken, french fries, etc., and an oil tank 10 filled with cooking oil and the oil tank 1
And a pulse combustor 20 for heating the oil in 0. The pulse combustor 20 includes a combustion chamber 21 provided in the oil tank 10 in which pulse combustion is performed, and a tail pipe 22 meandering in the oil tank 10 serving as a discharge passage of high-temperature combustion exhaust gas from the combustion chamber 21. Made of tail pipe 2
The oil in the oil tank 10 is heated by the heat radiation from the outer wall of No. 2. A temperature sensor 11 for detecting the oil temperature in the oil tank 10 is provided on the side wall of the oil tank 10.

On the other hand, the air supply system to the combustion chamber 21 includes an air blower 24 for sucking the combustion air, an air supply muffler 25 provided on the downstream side of the air blower 24, and a combustion air after passing through the air supply muffler 25. Is supplied to the air chamber 26. Further, the fuel gas supply system includes a source electromagnetic valve 28 provided in the gas conduit 27 to control the opening and closing of the fuel gas passage, a main electromagnetic valve 29, and a gas chamber 30 provided in the air chamber 26.

In the air chamber 26, the gas chamber 3
A mixing chamber 31 is provided which is connected to 0 and is supplied with fuel gas and combustion air.
1 is configured to be supplied. In the combustion chamber 21,
Spark plug 32 for igniting the air-fuel mixture at the start of combustion
And a frame rod 33 which is a flame detection element.

The pulse combustor 20 repeats explosive combustion in a constant cycle by taking advantage of self-ignition during normal combustion and natural suction of combustion air. A flap valve (not shown) is provided at the inlet of the mixing chamber 31 (fuel gas and combustion air supply port) so that the combustion exhaust gas does not flow back to the air supply source side.

In order to control the combustion of the pulse combustor 20, a controller 40 is provided inside the main body case. The controller 40 includes a CPU, a ROM, and a RAM (not shown) forming a well-known arithmetic and logic operation circuit, an input interface (not shown) for inputting signals from the temperature sensor 11 and the frame rod 33, and an original solenoid valve 28. It is a so-called microcomputer including a main solenoid valve 29, a blower 24, an output interface (not shown) for outputting a control signal to the ignition igniter 34, and the like.

Here, the combustion control of this embodiment will be described in comparison with the combustion control of the prior art. In the combustion control according to the conventional technique, heating on / off is controlled only based on the liquid temperature, so that the arrows C and D in FIG.
When a steep temperature gradient occurs, the overshoot becomes excessive and the liquid temperature largely deviates from the desired temperature range.

Therefore, in the combustion control of the present embodiment, by performing on / off control of heating based on the liquid temperature and the temperature gradient, for example, a new food item is put into the oil tank 10 and the arrow C in FIG. When such a sudden temperature drop occurs, heating is started at a temperature higher than the normal heating ON temperature, thereby preventing the liquid temperature from falling outside the desired temperature range and significantly decreasing. On the contrary, for example, when the temperature of the input cooking target is higher than the oil temperature of the oil tank 10,
When a sudden temperature rise occurs (arrow D in FIG. 2),
By ending the heating at a temperature lower than the normal heating-off temperature, the liquid temperature is prevented from rising outside the temperature range and rising significantly.

As described above, the combustion control of this embodiment enables more accurate temperature control, and the liquid temperature does not largely deviate from the desired temperature range even when a rapid temperature change occurs. Also, the switch operation by the cook is not necessary here.

Further, another combustion control in this embodiment will be described with reference to the flow chart shown in FIG. In this combustion control routine, the liquid temperature detected by the temperature sensor 11 is input to the controller 40 every 0.1 seconds (step (hereinafter abbreviated as S) 1). Then, when the liquid temperature is input 10 times (S2: Yes), the average liquid temperature of 10 times, that is, 1 second is calculated (S3).

Then, in S4, it is judged whether or not there is data of the last one second average temperature, and if there is no data (S4: No), the process returns to S1, and if there is data (S4).
4: Yes), the process proceeds to S5, and whether the temperature gradient is positive or negative is determined based on the previous average liquid temperature and the current average liquid temperature. Then, in S6, the temperature difference between the previous average liquid temperature and the current average liquid temperature is calculated to obtain the temperature gradient.

Then, in S7, it is judged whether or not the pulse combustor 20 is in the ON state. Pulse combustor 20
Is on (S7: Yes), the process of mode A (burner on state → off temperature determination) described later is performed in S8, and if it is off (S7: No), S is performed.
Mode B processing (burner off state →
ON temperature determination) is performed, and the process returns to S1.

Next, the processing of mode A performed in S8 will be described with reference to the flowchart shown in FIG.
This process is a process performed when the pulse combustor 20 is in the ON state, and determines the temperature at which the pulse combustor 20 is turned off (hereinafter referred to as the off temperature). Whether the temperature gradient is positive / negative and the temperature difference between the previous average temperature and the current average temperature is 0.25 ° C. or more is determined based on the determination result in S5 and the calculation result in S6.
The determination is made in S12, and the process proceeds to any of S13, S14, S15, and S16.

That is, it is determined in S10 whether the temperature gradient is positive, and when it is determined to be positive (S10: Yes).
Then, in S11, the temperature rise is 0.25 ° C / s.
It is determined whether or not ec or more. And the temperature rise is 0.
When it is judged to be less than 25 ° C / sec (S11: N
In o), in S13, the off temperature is determined to be 3 ° C lower than the upper limit temperature of the desired temperature range (hereinafter, simply referred to as the upper limit temperature, which is set in advance).

In S11, the temperature rise is 0.25 ° C /
If it is determined that the time is longer than sec (S11: Yes),
In S14, the off temperature is determined to be 4 ° C lower than the upper limit temperature.

When the temperature gradient is determined to be negative in S10 (S10: No), it is next determined in S12 whether the temperature decrease is 0.25 ° C./sec or more.
When it is determined that the temperature decrease is less than 0.25 ° C / sec (S12: No), the off temperature is determined to be 2 ° C lower than the upper limit temperature in S15. When it is determined in S12 that the temperature decrease is 0.25 ° C./sec or more (SS12: Yes), the off temperature is kept at the upper limit temperature (S16).

Next, the processing of the mode B performed in S9 will be described with reference to the flowchart shown in FIG.
This process is a process performed when the pulse combustor 20 is in the off state, and determines the temperature at which the pulse combustor 20 is turned on (hereinafter referred to as the on temperature). Whether the temperature gradient is positive or negative and the temperature difference between the previous average temperature and the current average temperature is 0.25 ° C. or more is determined based on the determination result of S5 and the calculation result of S6.
The determination is made in S19, and the process proceeds to any of S20, S21, S22, and S23.

That is, whether or not the temperature gradient is positive is determined in S17, and when it is determined to be negative (S17: No), the temperature decrease is next 0.25 ° C./se in S18.
It is determined whether or not it is greater than or equal to c. And the temperature drop is 0.2
When it is determined that the temperature is 5 ° C / sec or more (S18: Ye
In s), in S20, the ON temperature is determined to be 4 ° C. higher than the lower limit temperature of the desired temperature range (hereinafter, simply referred to as the lower limit temperature, which is preset). S18
When it is determined that the temperature decrease is less than 0.25 ° C / sec in S (S18: No), the ON temperature is determined to be 2 ° C higher than the lower limit temperature in S21.

If the temperature gradient is judged to be positive in S17 (S17: Yes), it is then judged in S19 whether the temperature rise is 0.25 ° C./sec or more. When it is determined that the temperature rise is 0.25 ° C./sec or more (S19: Yes), the ON temperature is kept at the lower limit temperature (S22). When it is determined that the temperature rise is less than 0.25 ° C / sec in S19 (S1
9: No), the ON temperature is determined to be 1 ° C. higher than the lower limit temperature in S23.

The above-mentioned processing in modes A and B will be described in more detail with reference to FIG. FIG. 7 is an example of a graph showing changes with time of the liquid temperature detected by the temperature sensor 11 in the temperature control device of the present embodiment.

First, when nothing is added to the cooking liquid, it is considered that the temperature changes as shown in FIG. 7 (a).
Here, in the period A, the pulse combustor 20 is in the ON state,
The detected liquid temperature is gentle (the absolute value of the temperature gradient is 0.25
It means that it is less than ° C. The same shall apply hereinafter). The case of S15 occurs within this period, and the OFF temperature is determined to be 2 ° C. lower than the upper limit temperature T4.

When the temperature gradient turns positive, the period B starts. In the period B, the pulse combustor 20 is in the ON state,
The detected liquid temperature is rising slowly. The case of S13 occurs within this period, and the off temperature is the upper limit temperature T4.
The temperature is corrected to 3 ° C lower. When the liquid temperature rises to the off temperature, the pulse combustor 20 is turned off. That is,
The temperature T3 in FIG. 7A is the off temperature determined in S13.

Since the pulse combustor 20 has been turned off, the period C starts. In the period C, the pulse combustor 20 is in the off state, and the detected liquid temperature gradually rises.
The case of S23 occurs within this period, and the ON temperature is determined to be 1 ° C. higher than the lower limit temperature T1.

When the temperature gradient turns negative, the period D starts. In the period D, the pulse combustor 20 is in the off state,
The detected liquid temperature is gradually falling. The case of S21 occurs within this period, and the ON temperature is the lower limit temperature T1.
The temperature is corrected to 2 ° C higher. When the liquid temperature drops to the on temperature, the pulse combustor 20 is turned on. That is,
The temperature T2 in FIG. 7A is the ON temperature determined in S21. Then, since the pulse combustor 20 is turned on, the process returns to the period A and the cycle from the period A to the period D is repeated.

As a result, the time delay of the temperature change and the overshoot (T4-T3 and T2-T1) are canceled out so that the liquid temperature falls within the desired temperature range, S13,
The change width of the on or off temperature of S15, S21 and S23 is set.

Here, when the pulse combustor 20 is in the ON state,
When an object having a temperature significantly higher than the liquid temperature is thrown into the liquid while the detected liquid temperature is gradually increasing (corresponding to the period B), an arrow A in FIG. It is considered that a rapid temperature rise like the above occurs. At this time, the S
14 cases occur, the off temperature is 4 from the upper limit temperature T4.
It is corrected to a low temperature of ° C. As a result, when the liquid temperature rises to a temperature T6 lower than the temperature T3, the pulse combustor 20
Is turned off to avoid excessive overshoot. That is, the temperature T6 in FIG. 7B is the off temperature determined in S14.

On the other hand, when the pulse combustor 20 is in the off state and the detected liquid temperature is gradually decreasing (the period D
(Corresponding to), when an object whose temperature is significantly lower than the liquid temperature is put into the liquid (which often occurs in actual cooking),
It is considered that a rapid temperature drop occurs as shown by the arrow B in FIG. 7 (c). At this time, the case of S20 occurs,
The ON temperature is corrected to a temperature higher than the lower limit temperature T1 by 4 ° C. As a result, the pulse combustor 20 is turned on at the temperature T5 higher than the temperature T2, and excessive overshoot is avoided. That is, the temperature T5 in FIG. 7C is the ON temperature determined in S20.

As described in detail above, in the temperature control device according to the present embodiment, the combustion control is performed based on not only the liquid temperature but also the temperature gradient, the positive / negative of the temperature gradient, and the ON / OFF of the pulse combustor 20. Since this is performed, more accurate temperature control becomes possible, and the liquid temperature does not largely deviate from the desired temperature range even if a sharp temperature gradient occurs. Also, the switch operation by the cook is not necessary here. Further, since the number of times the pulse combustor 20 is turned on and off does not significantly increase, the control circuit and the ignition circuit are not unduly deteriorated.

The above embodiment is not intended to limit the present invention, and it is needless to say that various modifications and improvements can be made without departing from the gist of the present invention. For example,
Although this embodiment is applied to a fryer, it can be applied to various cooking devices. Further, the heating source is not limited to the pulse combustor, but may be one using a Bunsen burner or one using an electric heater. Further, in the above embodiment, the combustion control by the microcomputer has been described, but the present invention is not limited to this, and may be the discrete control by the configuration of the hardware circuit.

[0039]

As is apparent from the above description, according to the cooking liquid heating temperature control device of the present invention, the liquid temperature and the temperature gradient are used, or the liquid temperature, the temperature gradient, and the positive / negative of the temperature gradient are controlled. Since the combustion is controlled by turning the heating on and off, accurate temperature control can be performed without requiring the switch operation by the cook. Further, the problem of durability due to deterioration of the heating on / off control circuit and the like is avoided, and therefore the effect of the cooking liquid heating temperature control device of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of a cooking utensil including a liquid heating temperature control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a change over time in a liquid temperature detected by a temperature sensor in the cooking appliance with temperature control according to the present invention.

FIG. 3 is a diagram showing a change over time in a liquid temperature detected by a temperature sensor in a cooking appliance with temperature control based on a conventional technique.

FIG. 4 is a flowchart showing a combustion control routine in temperature control according to the present invention.

FIG. 5 is a flowchart showing a combustion control routine in temperature control according to the present invention.

FIG. 6 is a flowchart showing a combustion control routine in temperature control according to the present invention.

7 (a), (b), (c) are diagrams showing a change over time in the liquid temperature detected by a temperature sensor in the temperature control according to the present invention.

[Explanation of symbols]

 11 temperature sensor 20 pulse combustor 40 controller T1 lower limit of set temperature range T2, T5 temperature at which heating is turned on T3, T6 temperature at which heating is turned off T4 upper limit of set temperature range

Claims (1)

[Claims] 1. A heating means for heating a cooking liquid medium for cooking an object to be cooked, a liquid temperature detecting means for detecting a temperature of the liquid medium heated by the heating means, and the liquid temperature detecting means. A temperature gradient detecting means for detecting the temperature gradient of the liquid medium detected by the temperature gradient, and when the detected temperature gradient tends to increase, the temperature rise before the upper limit value of the heating temperature setting range of the liquid medium When the heating means is turned off at a temperature according to the degree and the temperature gradient tends to decrease, the heating means is turned on at the temperature according to the temperature decrease degree before reaching the lower limit value of the heating temperature setting range of the liquid medium. A cooking liquid heating temperature control device, comprising: a temperature control means for turning on.