JP3043906B2 - Cooking liquid heating temperature controller - Google Patents

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 apparatus, and more particularly, to a cooking utensil for cooking an object to be cooked via 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 Heretofore, in cooking utensils or the like for cooking an object to be cooked in a liquid medium (so-called "fried food", "boiled noodles", etc.), explosive combustion is used as a heating device, for example, a pulse burner. In some cases, only the on or off (combustion stop) due to the repetition of the above and no partial (low heat) state is used. In such a case, it is necessary to maintain a desired liquid temperature by controlling the on / off of the heating device. There is.

In such a case, the conventional temperature control generally includes a liquid temperature detector (for example, a thermistor, a thermocouple, or the like), 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 (end), 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. This turns on (starts) heating.

[0004] 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 that the liquid temperature is uniform due to convection of the liquid medium. This is because there is a time difference from when the heating is turned off to when the detected liquid temperature actually starts dropping. The same is true for the reason that the lower limit of the temperature range does not match the heating-on temperature. For this reason, the heating ON temperature and the heating OFF temperature are set in a desired temperature range in consideration of the overshoot of the temperature change.

[0005]

However, in such temperature control of cooking utensils and the like, the overshoot of the temperature change is not always constant. The overshoot changes due to a change in specific heat due to deterioration of the liquid (in this case, tempura oil or the like) or the incorporation of foreign matter, and a decrease in the heat capacity of the liquid caused by taking out the liquid during cooking. Furthermore, when a thing having a large temperature difference from the liquid medium enters, such as when a new object to be cooked is introduced, a large temperature gradient is temporarily generated as shown by an arrow C in FIG. In such cases, the overshoot increases.

In the conventional temperature control, the heating-on temperature and the heating-off temperature are fixed to predetermined values. In particular, if the setting is made in consideration of the overshoot in a state where the object to be cooked is not contained, There is a problem that the liquid temperature greatly deviates from the temperature range when a new object is introduced. Here, it is possible to alleviate this problem by setting the difference between the heating ON temperature and the OFF temperature small, that is, by setting the overshoot to be relatively large. However, in this case, the number of times the combustor is turned on and off is significantly increased, and thus there is a disadvantage that the durability of the control circuit and the ignition circuit is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object thereof is to provide a more accurate method based on a liquid temperature, a temperature gradient, and a result of ON / OFF determination of a heating device. It is an object of the present invention to provide a cooking liquid heating temperature control device capable of controlling the temperature of a liquid medium.

[0008]

In order to achieve the above object, a cooking liquid heating temperature control device according to the present invention comprises a 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 gradient of the temperature of the liquid medium detected by the liquid temperature detecting means, and the detected temperature gradient When the temperature is increasing, the heating means is turned off at a temperature corresponding to the degree of the temperature increase before reaching the upper limit of the heating set temperature range of the liquid medium. Before the lower limit of the heating set temperature range, the temperature control means for turning on the heating means at a temperature corresponding to the degree of temperature decrease is provided.

[0009]

According to the temperature control apparatus of the present invention having the above-mentioned structure, the object to be cooked is put into the liquid medium for cooking 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 is on the rise, the heating means is turned off at a temperature corresponding to the degree of the temperature rise before reaching the upper limit of the heating set temperature range of the object to be cooked, and the temperature gradient is on the decrease. Before reaching the lower limit value of the heating set temperature range, the temperature of the liquid medium is controlled by the temperature control means so that the heating means is turned on at a temperature corresponding to the degree of the temperature decrease. This prevents the liquid medium temperature from overshooting beyond the set temperature range.

[0010]

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

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

On the other hand, an air supply system to the combustion chamber 21 includes a blower 24 for sucking combustion air, an air supply muffler 25 provided downstream of the air blower 24, and a combustion air after passing through the air supply muffler 25. Is supplied to the air chamber 26. The fuel gas supply system includes a main solenoid valve 28 and a main solenoid valve 29 which are provided in a gas conduit 27 and controls opening and closing of a fuel gas flow path, and a gas chamber 30 provided in the air chamber 26.

The gas chamber 3 is provided in the air chamber 26.
0, a mixing chamber 31 is provided in which the fuel gas and the combustion air are supplied.
1 is provided. In the combustion chamber 21,
Spark plug 32 for igniting the mixture at the start of combustion
, A frame rod 33 as a flame detecting element is provided.

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

To control the combustion of the pulse combustor 20, a controller 40 is provided in the main body case. The controller 40 includes a CPU, a ROM, and a RAM (not shown) constituting 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, This is a so-called microcomputer comprising an output interface (not shown) for outputting a control signal to the main solenoid valve 29, the blower 24, the ignition igniter 34, and the like.

Here, the combustion control of this embodiment will be described in comparison with the combustion control according to the prior art. In the combustion control according to the prior art, the on / off of the heating is controlled based only on the liquid temperature.
When an abrupt temperature gradient occurs, the overshoot becomes excessive and the liquid temperature greatly deviates from a desired temperature range.

Therefore, in the combustion control of the present embodiment, for example, a new object to be cooked is put into the oil tank 10 by performing heating on / off control based on the liquid temperature and the temperature gradient, and the arrow C in FIG. When such a rapid temperature drop occurs as described above, heating is started at a temperature higher than the normal heating-on temperature, thereby preventing the liquid temperature from falling significantly outside the desired temperature range. Conversely, for example, when the temperature of the input cooked product is higher than the oil temperature of the oil tank 10,
When a rapid temperature rise occurs (arrow D in FIG. 2),
By ending the heating at a temperature lower than the normal heating-off temperature, the temperature of the liquid is prevented from rising significantly outside the temperature range.

As described above, in the combustion control of this embodiment, more accurate temperature control becomes possible, and the liquid temperature does not greatly deviate from a desired temperature range even when a sudden temperature change occurs. Also, here, no switch operation or the like by the cook is required.

Further, another combustion control in the present embodiment will be described with reference to a flowchart 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 second (step (hereinafter abbreviated as S) 1). Then, when the liquid temperature is input ten times (S2: Yes), the average liquid temperature is calculated ten times, that is, one second (S3).

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

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

Next, the mode A process performed in S8 will be described with reference to the flowchart shown in FIG.
This process is 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, the OFF temperature). Whether the temperature difference between the positive / negative of the temperature gradient and the previous average temperature and the present average temperature is 0.25 ° C. or more is determined based on the determination result in S5 and the calculation result in S6 in S10, S11,
The determination is made in S12, and the process proceeds to one of S13, S14, S15, and S16.

That is, it is determined whether or not the temperature gradient is positive in S10, and when it is determined to be positive (S10: Yes)
In step S11, the temperature rise is 0.25 ° C./s
ec is determined. And the temperature rise is 0.
When it is determined that the temperature is less than 25 ° C / sec (S11: N
In o), in S13, the OFF temperature is determined to be 3 ° C. lower than an upper limit temperature of a desired temperature range (hereinafter, simply referred to as an upper limit temperature; preset).

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 a temperature lower by 4 ° C. than the upper limit temperature.

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

Next, the processing in mode B performed in S9 will be described with reference to the flowchart shown in FIG.
This process is performed when the pulse combustor 20 is in the off state, and determines a temperature at which the pulse combustor 20 is turned on (hereinafter, an on-temperature). Whether the temperature difference between the positive / negative of the temperature gradient and the previous average temperature and the present average temperature is 0.25 ° C. or more is determined based on the determination result in S5 and the calculation result in S6 in S17, S18,
The determination is made in S19, and the process proceeds to any of S20, S21, S22, and S23.

That is, it is determined whether or not the temperature gradient is positive in S17, and if it is determined to be negative (S17: No), then in S18, the temperature decrease is 0.25 ° C./sec.
It is determined whether it is greater than or equal to c. And the temperature drop is 0.2
When it is determined that 5 ° C / sec or more (S18: Ye
In s), 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; preset) in S20. S18
If it is determined that the temperature decrease is less than 0.25 ° C./sec (S18: No), the on-temperature is determined to be a temperature 2 ° C. higher than the lower limit temperature in S21.

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

The processing in the modes A and B will be described in more detail with reference to FIG. FIG. 7 is an example of a graph showing a change 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 introduced into the cooking liquid, it is considered that the temperature changes as shown in FIG.
Here, during the period A, the pulse combustor 20 is in the ON state,
The detected liquid temperature is moderate (the absolute value of the temperature gradient is 0.25
゜ C, the same applies hereinafter). The case of S15 occurs during this period, and the OFF temperature is determined to be a temperature 2 ° C. lower than the upper limit temperature T4.

When the temperature gradient turns positive, the process proceeds to period B. In the period B, the pulse combustor 20 is in the ON state,
The detected liquid temperature is slowly rising. The case of S13 occurs during this period, and the off temperature is set to the upper limit temperature T4.
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 process proceeds to the period C. In the period C, the pulse combustor 20 is in the off state, and the detected liquid temperature is gradually rising.
The case of S23 occurs during 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 process proceeds to the period D. During the period D, the pulse combustor 20 is in the off state,
The detected liquid temperature is slowly falling. The case of S21 occurs within this period, and the ON temperature is lower than the lower limit temperature T1.
Corrected to 2 ° C higher. When the liquid temperature falls 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 burner 20 is turned on, the cycle 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) cancel each other out so that the liquid temperature falls within the desired temperature range.
The change width of the on or off temperature in S15, S21 and S23 is set.

Here, when the pulse combustor 20 is on,
When an object whose temperature is significantly higher than the liquid temperature is thrown into the liquid while the detected liquid temperature is slowly rising (corresponding to the period B), an arrow A in FIG. It is considered that such a rapid temperature rise occurs. At this time, the S
14 cases occur, and the off temperature is 4 times higher than the upper limit temperature T4.
Corrected to ゜ C lower temperature. As a result, when the liquid temperature rises to a temperature T6 lower than the temperature T3, the pulse combustor 20
Is turned off, and excessive overshoot is avoided. 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
If an object whose temperature is significantly lower than the liquid temperature is thrown into the liquid (which often occurs in actual cooking),
It is considered that a rapid temperature drop occurs as indicated by arrow B in FIG. At this time, the case of S20 occurs,
The ON temperature is corrected to a temperature 4 ° C. higher than the lower limit temperature T1. As a result, the pulse combustor 20 is turned on at a 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 above in detail, 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. As a result, more accurate temperature control becomes possible, and the liquid temperature does not significantly deviate from the desired temperature range even if a sharp temperature gradient occurs. Also, here, no switch operation or the like by the cook is required. And since the number of times of ON / OFF of the pulse combustor 20 does not increase remarkably, the control circuit and the ignition circuit are not unduly deteriorated.

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

[0039]

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

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram of a cooking appliance provided with a liquid heating temperature control device according to one embodiment of the present invention.

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

FIG. 3 is a diagram showing a time change of a liquid temperature detected by a temperature sensor in a cooking appliance based on 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.

FIGS. 7A, 7B, and 7C are diagrams showing a time change of a 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

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F23N 5/02 350 A47J 37/12

Claims (1)

(57) [Claims] 1. A heating unit for heating a cooking liquid medium for heating and cooking an object to be cooked, a liquid temperature detecting unit for detecting a temperature of the liquid medium heated by the heating unit, and a liquid temperature detecting unit. Temperature gradient detecting means for detecting the gradient of the temperature of the liquid medium detected by the method, when the detected temperature gradient is on the rise, before the temperature rises to the upper limit value of the heating set temperature range of the liquid medium. The heating means is turned off at a temperature according to the degree, and when the temperature gradient is in a downward trend, before reaching the lower limit value of the heating set temperature range of the liquid medium, the heating means is turned off at a temperature according to the degree of the temperature decrease. A cooking liquid heating temperature control device, comprising: a temperature control means for turning on.