JPH0646954A - Gas rice cooker - Google Patents

Abstract

PURPOSE:To cook a delicious rice by setting a boiling period to about 20 minutes irrespective of a rice-cooking quantity through obtaining the intensity of fire during the boiling period by fuzzy inference on the basis of the detected temperature of an inner pot and rice-cooking quantity and through opening and closing a plurality of control valves for adjusting fire. CONSTITUTION:An initial temperature detected by a thermistor is inputted to an arithmetic circuit 9 and first fuzzy inference part 8. The arithmetic circuit 9 obtains the average of temperature rise rates at several points of an inner pot and inputs it to the first fuzzy inference part 8. The first fuzzy inference part 8 fuzzy-infers a rice-cooking quantity by membership function and fuzzy rule and inputs the quantity to a second fuzzy inference part 11. The second fuzzy inference part 11 performs fuzzy inference from the temperature of the thermistor and the rice-cooking quantity, outputs a control output corresponding to fire during a boiling period to a controller 12, and controls opening and closing of a plurality of gas burners for adjusting fire. Thus, a delicious rice is cooked in about 20 minutes' boiling time irrespective of the rice-cooking quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas rice cooker, and more particularly to control of a boiling period in a rice cooking process.

[0002]

2. Description of the Related Art FIG. 10 is a diagram showing a temperature change in an inner pot of a gas rice cooker during rice cooking, in which T1 is a water absorption period, T2 is a heating period under high heat, and T3 is a boiling period.
T4 indicates the additional cooking period, and T5 indicates the uneven period.

Generally, it is known that delicious rice can be cooked when the boiling period T3 is set to 20 minutes. Conventionally, in this boiling period T3, the amount of cooked rice is "many",
A combination of "small" and "large", "medium", "small" of heat power, for example, if the amount of cooked rice is "large", the heat power is "large", or if the amount of cooked rice is "small" The fire power was set to "small" and it was performed at a constant heat power.

[0004]

As described above, in the prior art,
Since the heating power in the boiling period is not finely controlled according to the amount of cooked rice, the boiling period T3 does not reach 20 minutes,
There is a drawback that variations may occur and the cooked food may be in a “hard” or “watery” state.

The present invention has been made in view of the above points, and it is an object of the present invention to cook delicious rice with a boiling period of about 20 minutes regardless of the amount of cooked rice. And

[0006]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, according to the present invention, in a gas rice cooker having a detection element for detecting the temperature of the inner pot and having a plurality of control valves for adjusting the heating power, the temperature of the inner pot and the rice cooked by the detection elements are detected. A fuzzy inference unit that fuzzy infers a control output corresponding to the thermal power in the boiling period based on the amount, and controls the opening / closing time of each control valve based on the control output to adjust the thermal power in the boiling period. And a control unit.

[0008]

According to the above construction, the heat power during the boiling period is
Since it is controlled based on the amount of cooked rice and the temperature of the inner pot, the boiling period can be set to about 20 minutes, and delicious rice can be cooked.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a gas rice cooker according to an embodiment of the present invention. In the figure, 1 is an inner pot, 2 is a thermistor as a detection element for detecting the temperature of the inner pot 1,
3 is a flame rod for detecting a flame, 4 is an ignition transformer for igniting gas, 5 is a main valve for opening and closing a gas flow path,
Reference numerals 6 and 7 are the first and second control valves for adjusting the thermal power, and the above configuration is basically the same as that of the conventional example. All valves 5
7 is open, the thermal power is "large", when the main valve 5 and the second control valve 7 are open, the thermal power is "medium", when the main valve 5 and the first control valve 6 are open, the thermal power is Is "small".

In the gas rice cooker of this embodiment, regardless of the amount of cooked rice, the boiling period is maintained at about 20 minutes so that delicious rice can be cooked. The heating power in is adjusted by controlling the opening and closing of the first and second control valves 6 and 7 in a time-sharing manner.

That is, in the second fuzzy inference unit 11,
Based on the amount of cooked rice from the first fuzzy inference unit 8 and the temperature of the inner pot 1 detected by the thermistor 2, fuzzy inference is performed as described later and a control output corresponding to the heating power in the boiling period is sent to the control unit 12. Then, the control unit 12 controls the opening / closing time of each of the control valves 6 and 7 corresponding to this output to adjust the thermal power in the boiling period.

The boiling period is determined in the same manner as in the conventional case.
When the temperature of the inner pot 1 reaches about 80 ° C. after starting the rice cooking, it is determined that the boiling period has started.

In the first fuzzy inference unit 8, the thermistor 2
Initial temperature of the inner pot 1 detected by the operation circuit 9
The temperature increase rate of the inner pot 1 calculated as described below is input, and fuzzy inference is performed based on the membership function and the fuzzy rule to perform the second fuzzy inference unit 1.
The amount of cooked rice is output to 1. Since the initial temperature of the inner pot 1 before heating is started varies considerably depending on the season, by using this initial temperature as the input variable of the first fuzzy inference unit 8,
The amount of cooked rice is predicted more accurately.

In the arithmetic circuit 9 of this embodiment, the output of the thermistor 2 is differentiated at the initial rise in the water absorption period T1 of FIG. 10 to calculate the average value of the temperature rising rates at several points, and this average value is calculated. It is output to the first fuzzy inference unit 8.

The structure and operation of the first fuzzy inference unit 8 will be described.

FIG. 3A shows a membership function of the initial temperature of the inner pot 1 which is an input variable of the first fuzzy inference unit 8 and has three labels of NB, ZR and PB.
(B) shows the membership function of the temperature rise rate which is also an input variable, and has five labels of NB, NS, ZR, PS and PB.

On the other hand, the amount of cooked rice which is an output variable is shown in FIG.
As shown in (C), NB, NS, ZR, PS, P
It has the five labels of B and the corresponding membership function values.

When the initial temperature and the temperature rise rate of the inner pot 1 are given, the conformity of the input variable of each label is calculated in the corresponding rule among the fuzzy rules shown in FIG. 4, and each rule is calculated. The smallest value is selected as the fitness of the input variable for each case (MIN operation).

Next, the goodnesses of fit of the input variables in each of the above rules are multiplied by the membership function values of the corresponding output variable labels, and the sum of all the multiplication values is added to the goodness of fit of the input variables. The rice cooking amount is calculated by dividing by the total value of (MAX operation).

Next, based on the amount of cooked rice from the first fuzzy inference unit 8 and the temperature of the inner pot 1 detected by the thermistor 2, fuzzy inference is performed to obtain a control output corresponding to the heating power in the boiling period. The configuration and operation of the second fuzzy inference unit 11 which outputs to 12 will be described.

FIG. 5A shows the membership function of the amount of cooked rice which is an input variable of the second fuzzy inference unit 11, where N
It has five labels B, NS, ZR, PS, PB, and FIG. 5 (B) shows the membership function of the temperature of the inner pot 1 which is also an input variable, NB, NS, ZR, PS, PB. It has 5 labels.

On the other hand, the control output corresponding to the thermal power during the boiling period, which is an output variable, is NB, N as shown in FIG.
It has seven labels, M, NS, ZR, PS, PM and PB, and corresponding membership function values.

In this embodiment, the second fuzzy inference unit 11
The control output from is the opening (O) of the first and second control valves 6 and 7.
N) Given as time.

Here, the adjustment of the thermal power by controlling the opening / closing time of the first and second control valves 6 and 7 will be described.

When only the first control valve 6 is opened in the state where the main valve 5 is opened and the gas flow path is opened, FIG.
As shown in FIG. 7, the thermal power becomes “small”, and when only the second control valve 7 is opened, the thermal power becomes “medium” as shown in FIG. 7B, and the first and second control valves 6 Open both 7 and 7.
When it is set, the thermal power becomes “large” as shown in FIG. 7 (C). The conventional adjustment of thermal power is performed in three stages.

In this embodiment, the second fuzzy inference unit 11
Based on the control output from, for example, as shown in FIG. 8 (A), the first control valve 6 and the second control valve 7 are alternately opened and closed to adjust the heating power to "slightly small". Or
Alternatively, as shown in FIG. 8B, the second control valve 7
By opening and closing only the first control valve 6 in a state in which is set to "open", the thermal power is adjusted to "slightly large".

In this embodiment, one opening / closing cycle T is 18
It is 0 seconds, and only the second control valve 7 is in the “open” period T6.
And a period T7 in which both the first and second control valves 6 and 7 are "open".
Is supplied from the second fuzzy inference unit 11 as a control output.

In the second fuzzy reasoning section 11, when the amount of cooked rice and the output of the thermistor 2 are given in the boiling period, the input variables of the respective labels are changed in the corresponding fuzzy rules shown in FIG. The goodness of fit is calculated, and the smallest value is selected for each rule as the goodness of fit of the input variable (MIN operation).

Next, the goodness of fit of the input variable in each of the above rules is multiplied by the membership function value of each corresponding output variable label in FIG. 6, and the sum of all the multiplication values is added to the input variable. The control output corresponding to the thermal power in the boiling period, that is, the period T6 or T7 described above is calculated by dividing by the total value of the goodness of fit of the control valve 6, according to the control output.
The opening / closing time of 7 is controlled.

The control unit 12 determines whether the control output from the second fuzzy inference unit 11 is the period T6 or the period T7 as follows. That is, it is determined whether the control output from the second fuzzy inference unit 11 is smaller or larger than 90 seconds corresponding to the thermal power "medium", and when it is smaller, only the second control valve 7 is opened. Period T
It is judged that it is 6, and as shown in FIG.
The second control valves 6 and 7 are controlled, and when they are large, it is determined that it is a period T7 in which both the first and second control valves 6 and 7 are "open", and as shown in FIG. 1, to control the second control valves 6 and 7. In addition, when it is 90 seconds, FIG.
As shown in (B), the heat power is set to "medium".

In this way, based on the amount of cooked rice and the temperature of the inner pot 1, the fuzzy inference is made on the control output corresponding to the thermal power during the boiling period, and the control output is used to output the first and second control valves 6, 7
Since the heating power is adjusted by controlling the opening / closing time of, the boiling period can be set to about 20 minutes (15 minutes to 25 minutes), which allows the cooked food to be cooked like the conventional example in which the heating power was constant. It is possible to effectively prevent "hard" or "watery" state.

In the above-described embodiment, the amount of cooked rice is fuzzy inferred by the first fuzzy inference unit 8 based on the initial temperature of the inner pot 1 and the rate of temperature rise, but as another embodiment of the present invention, The user may input the amount of cooked rice with an operation switch or the like.

[0034]

As described above, according to the present invention, since the heating power during the boiling period is controlled by fuzzy inference according to the amount of cooked rice and the temperature of the inner pot, the boiling period can be set to about 20 minutes. , It becomes possible to cook delicious rice.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a gas rice cooker according to an embodiment of the present invention.

FIG. 2 is a block diagram of a main part of the embodiment of FIG.

FIG. 3 is a diagram showing an example of a membership function used in a first fuzzy inference unit.

FIG. 4 is a diagram showing an example of a fuzzy rule used in a first fuzzy inference unit.

FIG. 5 is a diagram showing an example of a membership function of an input variable of a second fuzzy inference unit.

FIG. 6 is a diagram showing an example of a membership function of output variables of a second fuzzy inference unit.

FIG. 7 is a diagram showing a relationship between opening / closing of a control valve and thermal power.

FIG. 8 is a diagram showing a relationship between opening and closing of a control valve of the present invention and thermal power.

FIG. 9 is a diagram showing an example of a fuzzy rule used in a second fuzzy inference unit.

FIG. 10 is a diagram showing changes in temperature of the inner pot.

[Explanation of symbols]

 1 Inner pot 2 Thermistor 6, 7 1st, 2nd control valve 8 1st fuzzy inference part 9 Arithmetic circuit 11 2nd fuzzy inference part 12 Control part

Claims (1)

[Claims] 1. A gas rice cooker having a detection element for detecting the temperature of the inner pot and having a plurality of control valves for adjusting heat power, wherein the temperature of the inner pot and the amount of cooked rice are detected by the detection elements. A fuzzy inference unit that fuzzy infers a control output corresponding to the thermal power in the boiling period, and a control unit that controls the opening / closing time of each control valve based on the control output to adjust the thermal power in the boiling period, A gas rice cooker characterized by comprising.