JPH04224713A - rice cooker - Google Patents

Abstract

PURPOSE:To cook rice tastily by performing heating in response to a quantity of rice. CONSTITUTION:After a specified period of time has passed since the start of cooking of rice, the temperature of an inner pan 5 is detected by a thermistor 2. Then, a difference to temperature variation quantity in a fixed period of time and ideal temperature is calculated. The temperature ascent of rice is assumed, based on the information. A heating quantity to a heating device 1 in the next specified period of time is determined. The rice is cooked by connecting the heating device 1 with power in such a manner that the heating quantity can be provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to temperature control for heating, keeping warm, etc. of a rice cooker.

0002

BACKGROUND OF THE INVENTION Conventional rice cookers first preheat the rice in order to make it sufficiently absorb water and to obtain uniform gelatinization when heated.

[0003] In the preheating process, the preheating time is determined from a small number of options, such as whether to perform the preheating process or omit the preheating, based on temporary information from a bottom thermistor installed at the bottom of the rice cooker. There is.

After the preheating process is completed, as shown in FIG. 20, a certain amount of heating is carried out according to the content of the rice until boiling of the rice is detected from the output information of the thermistor that detects the temperature of the content.

[0005] When the rice is cooked, it is heated for a while and then kept at a constant temperature. When it comes to keeping rice delicious and warm, it is generally said that it is best to keep the temperature of rice constant at around 73°C, and the warming temperature is also set at 73°C.

[0006] In addition, in a rice cooker, when cooking porridge in which the amount of water per rice is larger than when cooking white rice, as shown in Fig. 21, after the preheating process is completed, a thermistor that detects the temperature of the contents is set at a temperature The rice porridge is cooked by cooking the rice at a certain amount of heat until the temperature reaches 98 degrees Celsius or higher, and then maintaining the boiling state for a certain period of time at an internal temperature of 98°C or higher.

[0007]

In the above-mentioned prior art, it is known that in the preheating step, the water absorption rate of rice changes depending on the temperature of the water in which it is soaked, and it becomes necessary to change the preheating time due to seasonal fluctuations. Furthermore, if there is a difference between the temperature of the rice cooker and the temperature of the rice, it is difficult to accurately determine the water temperature using conventional temperature detection means and methods.

[0008] Therefore, in winter, the water temperature becomes low and the rice does not absorb enough water, and if the temperature of the rice cooker is high due to continuous use, the temperature of the rice cooker may be low even though the temperature of the contents is low. First, due to erroneous recognition, the preheating time was shortened, leading to insufficient water absorption and resulting in poor-tasting rice.

[0009] When cooking rice, by heating the rice so that it boils in about 10 minutes after absorbing water, water absorption is promoted even while the temperature is rising, and the degree of gelatinization is therefore sufficient, and the rice in the rice cooker is heated. It is known that the difference in moisture content and hardness between the upper and lower sides of the glass is also reduced.

[0010] In conventional rice cookers, since the amount of heating is constant, there is a large difference in boiling time depending on the content, and especially in a small capacity, there are cases where water absorption is insufficient and the rice tastes bad. Furthermore, if an excessive amount of heating is applied, it may cause boiling over of the solution containing eluted starch and the like.

[0011] When keeping the rice warm, this heat keeping control is performed using a bottom thermistor, and the keep warm temperature is set with the lid closed. When the lid is opened, the drop in the surface temperature of the rice is not taken into account; for example, even if the lid is opened for 2 minutes, the bottom thermistor will not be able to detect the opening of the lid, and the surface temperature of the rice will be the original temperature after the lid is closed. It takes about an hour or more for the rice to warm up, and the surface temperature of the rice deviates significantly from the keeping temperature each time the lid is opened and closed.

[0012] Furthermore, porridge has a high ratio of water to rice, and when heated, rice starch and the like are eluted, producing a sticky aqueous solution, which tends to bump when it approaches its boiling point.

Furthermore, even if the heating element accumulates heat and stops heating, the porridge receives conduction heat and heating cannot be stopped immediately. Therefore, in conventional rice cookers, it is necessary to minimize heat accumulation in the heating element and to reduce the output at a temperature lower than the boiling point. As a result, it takes a long time to boil, and the rice grains may become crushed, resulting in an unpalatable product. Furthermore, fluctuations in voltage tend to cause variations in rice cooking time and finished product.

[0014] In view of the above, an object of the present invention is to provide a rice cooker capable of producing delicious rice or porridge.

[0015]

[Means for Solving the Problems] The means for solving the problems according to claim 1 of the present invention, as shown in FIG. Based on the output information from the temperature detector 2 and the content temperature detector 2, the preheating time is inferred and determined based on the detected temperature and the amount of temperature change over a certain period of time in order to ensure that the rice absorbs water and is heated and gelatinized uniformly. The preheating control device 3 is equipped with a preheating control device 3 that performs the following.

In claim 2, as shown in FIG. 8, there is provided a heating device 1 for heating and boiling rice, a content temperature detector 2 for indirectly detecting the temperature of the content, and the content temperature detector 2. In order to control the time until the rice boils within a certain range based on the output information from Heating control device 2 that infers and determines the heating amount of heating device 1
1.

In claim 3, as shown in FIG. 14, a heating element 7 that heats the rice that has been kept warm, a room temperature detector 30 that detects the room temperature, and a lid opening/closing detector 3 that detects opening and closing of the rice cooker lid 6.
1, and energizing the heating element 7 so that the rice surface temperature, which has decreased based on the room temperature output information from the room temperature detector 30 and the lid open time output information from the lid opening/closing detector 31 when the lid is opened, becomes the heat retention temperature. It is equipped with a heat retention control device 32 that infers and determines the time.

In claim 4, as shown in FIG. 18, there is provided a heating device 1 for heating and boiling rice to make porridge, a content temperature detector 2 for indirectly detecting the temperature of the content, and a content temperature detector 2 for indirectly detecting the temperature of the content. Based on the output information from the detector 2, in order to prevent the porridge from boiling over, the heating device 1 is configured to adjust the temperature of the contents according to the amount of temperature change over a certain period of time and the difference from the ideal temperature of the contents at the time of temperature detection. The porridge heating control device 40 inferentially determines the heating amount of the porridge.

[0019]

[Operation] In the problem solving means according to claim 1, when rice cooking is started, the temperature of the contents at a predetermined time is detected by the contents temperature detector 2, and based on this information, the preheating control device 3 controls the detected temperature. The amount of change and the temperature reached after a predetermined period of time are calculated, the temperature of the contents is predicted using these two factors as input factors, and fuzzy inference is performed using the operation amount of the heating device 1, that is, the preheating time as an output factor. The optimum preheating time is then determined. Then, the contents are preheated for the determined preheating time.

According to claim 2, after the preheating is completed, the temperature of the contents is detected by the contents temperature detector 2 at a predetermined time, and based on this information, the heating control device 21 determines the amount of temperature change for a predetermined time and the predetermined time. Calculate the difference from the ideal temperature at the elapsed time, use these two factors as input factors to predict the temperature rise curve according to the amount of contents, and calculate the operation amount of the heating device 1 within the next predetermined time, that is, the heater energization Fuzzy inference using time or power as an output factor is performed to determine the amount of heating. Then, the contents are heated by the determined heating amount to achieve an ideal temperature rise.

According to claim 3, during heat retention, after the lid 6 is opened and the lid 6 is closed after a while, the room temperature output information from the room temperature detector 30 and the lid opening information from the lid opening/closing detector 31 are detected. The surface temperature of the rice is predicted by the heat retention control device 32 using the output information for time as the input factor, and fuzzy inference is performed using the energization time of the heating element 7 as the output factor so that the surface temperature of the rice becomes the heat retention temperature. The energization time is determined. Then, the surface of the rice is heated for the determined energization time.

According to claim 4, the temperature of the content is detected by the content temperature detector 2 at a predetermined time, and based on this information, the porridge control device 40 determines the amount of temperature change over a predetermined time and the ideal value at the time when the predetermined time elapses. Calculate the difference from the temperature, use these two factors as input factors to predict a temperature rise curve according to the amount of contents, and calculate the operation amount of the heating device 1 within the next predetermined time,
That is, fuzzy inference is performed using the heater energization time or the amount of electric power as an output factor, and the amount of heating is determined.

[0023] Then, the contents are heated by the determined heating amount to achieve an ideal temperature rise. When the temperature of the contents rises rapidly and exceeds the ideal temperature, the amount of operation of the heating device 1 is reduced to prevent bumping. Conversely, when the temperature rise is small, the manipulated variable is set to be large. Therefore, when cooking rice porridge, boiling is controlled by adjusting the amount of operation according to the temperature rise of the contents to eliminate boiling over.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of each claim of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a functional block diagram of a rice cooker showing a first embodiment of the present invention, FIG. 2 is a control block diagram, FIG. 3 is a schematic diagram of the rice cooker, and FIG. 4 is a fuzzy inference diagram. Figures 5-A and 5-B are diagrams showing the control law during fuzzy inference, Figure 6-A is a diagram showing the membership function for the thermistor detection level, and Figure 6-B is the temperature change amount. Figure 6-C shows the membership function for
is a diagram showing the membership function for preheating control time,
FIG. 7 is a diagram showing a data table of output factors, that is, preheating control time, for input factors using the table lookup method.

The rice cooker of this embodiment includes a heating device 1 that preheats the rice to absorb water, a content temperature detector 2 that indirectly detects the temperature of the content, and The preheating control device 3 infers and determines the preheating time based on the detected temperature and the amount of temperature change over a certain period of time in order to ensure that the rice absorbs water and is uniformly heated and gelatinized based on the output information.

As shown in FIG. 3, the rice cooker has an inner pot 5 housed inside the rice cooker main body 4, which can be taken in and out, and a lid 6 attached to the top so that it can be opened and closed. A heating device 1 consisting of an electric heater is disposed at the bottom of the rice cooker main body 4, and a heat-retaining lid heating element 7 is housed in the lid 6. Also,
A heating element 8 for heat retention is arranged along the side surface of the inner pot 5. In addition, in the figure, 9 is an operation key.

The content temperature detector 2 is for relatively or absolute detection of the temperature of the mixed content of rice and water, and is made of a thermistor and is in contact with the inner pot 5 at the bottom of the rice cooker body 4. It is arranged like this.

The preheating control device 3 is composed of a microcomputer programmed to perform fuzzy control of the heating device 1 based on fuzzy reasoning, and as shown in FIG. A detected temperature change calculation means 10 calculates the amount of temperature change (dT/dt) in a predetermined time from the reached temperature up to the elapse of a predetermined time called detection time, and the two It has a content temperature prediction means 11 for predicting the temperature of the content based on an input factor, and a preheating time determining means 12 for inferentially determining the optimal preheating time corresponding to the predicted temperature from among a plurality of categories. .

Further, the preheating control device 3 includes, as shown in FIG.
On the input side are a rice cooking key 13a for starting rice cooking, a key circuit 13 such as a rice cooking time setting key, and a contents temperature detector 2.
Temperature detection circuit 1 that calculates the temperature from the resistance value of the thermistor
4 is connected. A rice cooking relay drive circuit 15 for driving the heating device 1 and a display circuit 16 for displaying input data from the key circuit 13 are connected to the output side. In addition, in FIG. 2, 17 is a CPU, 18 is a RAM, 19
is a ROM.

In the above configuration, when the rice cooking key 13a is pressed, rice cooking starts, and the preheating control device 3 starts predicting the temperature of the contents. The process of this prediction is as follows.

When rice cooking is started, the detected temperature change amount calculating means 10 calculates the detected temperature change amount based on the information from the thermistor 2 and the reached temperature after the predetermined time has elapsed within a predetermined time period called the initial temperature detection time. Then, the content temperature predicting means 11 predicts the temperature of the content using these two factors as input factors, and the preheating time determining means 12 performs fuzzy inference using the manipulated variable, that is, the preheating time as an output factor, to determine the optimal The preheating time is determined.

Here, input/output factors are shown in FIG. Thermistor detection level A after a predetermined time elapses after the start of rice cooking
consists of three fuzzy labels: AH: high, AM: medium, and AL: low, and has seven resolutions in 10°C increments from 0°C. Further, the temperature change amount (dT/dt) B of the thermistor 2 within a predetermined time is composed of three fuzzy labels: BP: positive slope, BZ: lateral slope, BN: negative slope, -
It has eight resolutions in 5°C increments within the range from below 15°C to above +15°C.

The output factor determined by these two input factors is the preheating control time T, where NL: short, NM: slightly short, ZR: normal, PS: slightly long, P
Consists of 6 fuzzy labels: M: slightly long, PL: long, and the resolution is 7 x 8 5 based on input factors A and B.
There are 6 ways.

Note that FIG. 6 represents the membership function of each input factor, and the vertical axis represents the grade value of the membership function.

[0036] Fuzzy control is a control method in which a control law is described in an if-then- format using ambiguous natural language, and the input factors are the detected temperature A and the temperature change amount B, and the output factor is the preheating control time T. Then, the relationship between these can be expressed in the form if~then~ as follows.

[0037] if A is high and B
is Positive then This is Ne
Gative Large...(1) Equation (1) is a control law that says, "If the detected temperature is high and the temperature change has a positive slope, the preheating control time is shortened." Prepare multiple pieces like 5. In addition, in Figure 5,
This means that portions for which no control law is defined due to the matrix configuration are complemented by inferred approximations.

In this embodiment, inference is performed using the Min-Max-centroid method.

When the occurrence events for each input factor A and B are Ak (k is 0 to 6) and Bk (k is 0 to 7), the condition part satisfaction Ui (x) for the i-th of each control law is as follows. Membership values Ui(Ak) and U of each input factor
The smaller value of i(Bk) is taken.

That is, control law i: Ui(x)=min
When the condition part satisfaction corresponding to each control law is obtained as {Ui (Ak), Ui (Bk)}, the Max value, that is, the logical sum is determined based on the Min-Max method. The logical sum UT(x) for each control law is calculated as UT(x)=U1(x)∨U2(x) (2).

The actual manipulated variable, ie, the preheating control time T as an output factor, is calculated as the center of gravity of the logical sum.

T=∫x・UT(x)dx/∫UT(x)dx…(3)
In addition, as an actual control means, the Min set value corresponding to each control law, based on the occurrence event for the input factor,
A method of calculating the Max set value corresponding to all control laws and finding the center of gravity of the obtained set, that is,
Since the real-time inference method has a high possibility of complicating the process, it is necessary to predict the temperature of the contents in advance based on input factors (events that occur) and use fuzzy inference to determine the corresponding optimal preheating time control amount. The same effect can be obtained even if carried out by a so-called table lookup method in which the values are calculated and written as table values in the ROM 19 of the preheating control device 3 as shown in FIG.

A specific explanation will therefore be given based on the table pickup method.

[0044] By pressing the rice cooking key 13a, the CPU 17
After confirming the effectiveness of starting rice cooking, the controller moves to an initial temperature detection sequence for a predetermined time, and inputs and stores the output information of the thermistor 2 at the time of starting rice cooking.

When the predetermined time has elapsed, the output information from the thermistor 2 at that time is input, and the temperature detected by the thermistor 2 after the elapse of the predetermined time and the temperature at the start of cooking is determined to be within the predetermined time from the stored value. The amount of change is calculated, and the preheating time is referenced from the data ROM 19 based on these two factors.

Now, if the temperature detected by the thermistor 2 after a predetermined time has elapsed is 25°C, and the amount of temperature change within the predetermined time is -4°C, the temperature of the contents is predicted to be 15°C, and as shown in FIG.
The optimum preheating control time is determined to be 17 minutes from the data ROM 19 shown in , and the process shifts to preheating control.

Therefore, based on the output information from the content temperature detector 2, the temperature of the contents is determined by the detected temperature change amount (dT/dt) within a certain period of time after the start of rice cooking and the arrival at the point at which a certain period of time has elapsed. Two input factors of temperature can predict the temperature of the contents. Therefore, the optimal preheating time can be inferred and determined without being affected by water temperature, room temperature, or the temperature of the rice cooker, ensuring that the rice absorbs sufficient water and is uniformly heated and gelatinized, resulting in delicious rice. can be cooked.

Furthermore, by using the inference rules and the method of setting the membership function, it is possible to relatively easily adapt to the type of content temperature detector 2, the mounting position, the structure of the container body, etc.

[Second Embodiment] FIG. 8 is a functional block diagram of a rice cooker showing a second embodiment of the present invention, FIG. 9 is a diagram showing input/output specifications at the time of fuzzy inference, and FIGS. 10-A and B are fuzzy A diagram showing the control law at the time of inference, Fig. 11-A is a diagram showing the membership function for the difference between the detected temperature and the ideal temperature, Fig. 11-A.
B is a diagram showing the membership function with respect to the temperature gradient, FIG. 11-C is a diagram showing the membership function with respect to the amount of heating, FIG. 12 is a diagram showing a data table of the output factor, that is, the amount of heating, for the input factor using the table lookup method, and FIG. 13-A is a diagram showing a temperature rise model of the contents of this example, FIG. 13-B is a diagram similarly showing the ideal temperature curve of the thermistor, and FIG. ) shows the case where the rice is in a small capacity, and (b) shows the case in which the rice is in a large capacity.

The rice cooker of this embodiment includes a heating device 1 that heats rice to boil, a content temperature detector 2 that indirectly detects the temperature of the content, and a temperature sensor 2 that detects the temperature of the content indirectly. In order to control the time it takes for rice to boil within a certain range of time based on output information, a heating device is used that adjusts the amount of rice to boil depending on the amount of temperature change over a certain period of time and the difference from the ideal temperature of the contents at the time of temperature detection. 1, and a heating control device 21 for inferentially determining the amount of heating.

Note that the configuration of the rice cooker of this embodiment is the same as that of the first embodiment, and the heating control device 21 has the same circuit configuration as in FIG. 2 of the first embodiment, but the heating control device 2
1, as shown in FIG. 8, temperature gradient calculation means 22 calculates the temperature gradient (dT/dt) within a certain time from the temperature reached after a predetermined time elapses based on the output signal of the content temperature detector 2 after the completion of preheating. , a detected temperature difference calculating means 23 that calculates the difference (Ta - To) between the reached temperature Ta and the ideal temperature To at that point, and a temperature gradient and a detected temperature difference as input factors, and a temperature gradient of the contents using these two input factors. A temperature rise prediction means 24 predicts a temperature rise curve, and calculates the optimum heating amount within the next predetermined time from among a plurality of divisions for the heating amount of the heating device 1 in order to raise the temperature to the predicted temperature. The heating amount determining means 25 inferentially determines the energization time or the amount of electric power.

In the above configuration, after rice cooking starts and preheating is completed, the temperature gradient calculation means 22 calculates the temperature gradient based on the information from the thermistor 2 within a predetermined time, and the detected temperature difference calculation means 23 calculates the temperature gradient at the time when a predetermined time elapses. The difference from the ideal temperature is calculated, and using these two factors as input factors, the temperature rise prediction means 24 predicts the temperature rise curve of the contents, and the heating determination means 25 calculates the operation amount of the heating device 1 within the next predetermined time. That is, fuzzy inference is performed using the heater energization time or the amount of electric power as an output factor, the amount of heating is determined, and an ideal temperature increase is performed.

Here, the input/output factors are shown in FIG. The difference between the detected temperature after a predetermined period of time and the ideal temperature (Ta-T
o) A consists of three fuzzy labels: AB: positive, AZ: zero, AN: negative, and 5 from -10℃ or higher to 10℃ or higher.
It has six resolutions in degrees Celsius.

[0054] Also, the temperature gradient (dT/dt
)B consists of three fuzzy labels: BM: small, BR: medium, and BL: large, and has six resolutions depending on the detection temperature Ta, which has three resolutions.

The output factor determined by these two input factors is the heater ON time T, which is selected from five fuzzy labels: NL: small, NM: slightly small, ZR: normal, PM: slightly large, PL: large. The resolution is 108 (6×6×3) based on input factors A and B.
That's right.

Note that FIG. 11 shows the membership functions of each input/output factor.

[0057] When performing fuzzy control, FIG.
Prepare a plurality of control laws as shown in 0, and calculate Min-M
Perform inference using the ax-centroid method.

[0058] As an actual control means, M corresponding to each control law is
The method of calculating the in set value and the Max set value corresponding to all control laws and finding the center of gravity of the resulting set, that is, the method of reasoning in real time, has a high possibility of complicating the process. Therefore, input factor (
The temperature rise of the contents is predicted for the occurrence event), the corresponding optimal control amount is calculated by fuzzy reasoning, and is written as a table value in the ROM of the heating control device 21 as shown in FIG. Next, a specific example using the so-called table pickup method will be explained.

When the CPU 17 confirms that the preheating time has ended, it moves to the boiling detection sequence, and thermistor 2
Input and store output information.

The temperature gradient is calculated from the temperature detected by the thermistor 2 after a predetermined period of time and the previous stored value. Also, calculate the difference from the ideal temperature at that point. Based on these two elements, the operation amount for the next predetermined time is referred to from the data ROM 19. Thereafter, the process is repeated in the same manner until a predetermined time.

Now, the thermistor temperature at a certain point is 41.
2℃, the temperature after a predetermined time is 42℃, and the ideal temperature is 46℃.
℃, the data ROM 19 means that the next operation amount is 47/60 (78%) to turn on the heating device 1.

Therefore, based on the output information from the content temperature detector 2, the temperature of the contents is determined by the temperature gradient (dT/dt) within a certain period of time after the end of preheating and the temperature reached after a certain period of time. The difference between Ta and the ideal temperature at that point (
The temperature rise curve of the contents can be predicted by the two input factors Ta-To) and the next heating amount for the heating device 1 can be determined.

Therefore, as shown in FIG. 13, if the volume of rice is small, it is possible to reduce the heating amount of the heating device 1 before the temperature rises rapidly, the cooking time is stable, and gelatinization is sufficiently performed. You can get delicious rice and prevent boiling over.

[Third Embodiment] FIG. 14 is a functional block diagram of a rice cooker showing a third embodiment of the present invention, FIG. 15 is a diagram showing a control law during fuzzy inference, and FIG. 16-A is a membership function for room temperature. FIG. 16-B is a diagram showing the membership function with respect to the lid opening time, FIG. 16-C is a diagram showing the membership function with respect to the energization time of the lid heating element, FIG.
7 is a diagram showing a data table of output factors for input factors using the table lookup method.

The rice cooker of this embodiment includes a heating element 7 that heats the rice kept warm, a room temperature detector 30 that detects the room temperature,
A lid opening/closing detector 31 detects opening/closing of the rice cooker lid 6, and the rice surface temperature decreased based on room temperature output information from the room temperature detector 30 and lid opening time output information from the lid opening/closing detector 31 when the lid is opened. The heating element 7 is provided with a heat retention control device 32 that infers and determines the energization time to the heating element 7 so that the heating element 7 reaches the heat retention temperature.

The room temperature detector 30 is made of a thermistor and is disposed inside the rice cooker main body 4 so as to be in contact with the outside air.

The lid opening/closing detector 31 is composed of a micro switch, is assembled into a unit to mechanically detect opening/closing of the lid 6, and is attached to the rice cooker main body 4.

The heat retention control device 32 has the following functions as shown in FIG.
Room temperature information from room temperature detector 30 and lid opening/closing detector 31
A surface temperature prediction means 33 predicts the surface temperature of the rice using the two input factors, using the lid opening time information from the input factor, and a lid heating element 33 that predicts the surface temperature of the rice by using the lid opening time information from The heat retention amount determining means 34 infers and determines the energization time of 7 from among a plurality of categories. Note that the other configurations are the same as in the first embodiment.

[0069] In the above structure, the inside of the rice cooker is kept at 73°C using a heating element 9 usually located on the side of the inner pot 5.

[0070] When the lid 6 is opened and then closed after a while, the surface temperature of the rice decreases.

After closing the lid 6, the surface temperature prediction means 33 uses the output information from the room temperature detector 30 and the output information regarding the lid opening time from the lid opening/closing detector 31 as input factors.
The surface temperature of the rice is predicted, and the heat retention amount setting means 34
The lid heating element 7 is heated so that the surface temperature of the rice reaches the heat retention temperature.
Fuzzy inference is performed using the energization time as an output factor, the optimal energization time is determined, and the surface of the rice is heated.

Here, using the room temperature (K) and the lid opening time (t) as fuzzy variables, the value of the lid heating element energization time (Ht) is expressed as:
In order to make an inference using the software of the heat retention control device 32, the membership function and control law for each fuzzy label are set as follows.

FIG. 16 shows the membership function of each fuzzy label of each fuzzy variable. Figure 16-A is room temperature (K
), the horizontal axis is room temperature, and each fuzzy label is KZ: low, KS: high. Figure 16-B
is a membership function of the lid opening time (t), and the horizontal axis is the lid opening time from 0 to 120 seconds in this embodiment. Each fuzzy label is ZR: short, ZM: medium, ZB:
It is long.

FIG. 16-C shows the energization time (Ht
) is the membership function of 6 to 18 in this example.
It's a minute's time. Each fuzzy label is MR: short, MM
: Medium, MA: Slightly long, MB: Long. The vertical axes are the grade values of the membership functions.

As for the control law, the following six IF and THEN rules are set to perform the inference control of this embodiment.

IF K=KS and t=ZR, THE
N Ht=MR IF K=KZ and
t=ZR, THEN Ht=MM IF K=K
S and t=ZM, THEN Ht=MM
IF K=KZ and t=ZM, THEN
Ht=MA IF K=KS and t
=ZB, THEN Ht=MA IF K=KZ
and t=ZB, THEN Ht=MBFigure 1
5 shows this control law in a matrix table. In this example, the part between each fuzzy variable is MIN-MA
Find and complement the inferred approximate value using the X-center of gravity method.

In this embodiment, the membership function is defined as a straight line, but it may be defined as a sine curve or the like depending on the detection characteristics of the room temperature detector 30.

Based on this control law and the two input factors, a conclusion section as an output factor shown in FIG. 16-C is drawn. Next, to determine the control amount, the center of gravity of the logical function is taken as the energization time (Ht*) of the lid heating element 7, and the center of gravity of the logical function is determined in the same manner for all conditional parts of the membership function.

Ht*=ΣXi*Yi/ΣYi... (4) In this embodiment, a table pull-up inference method is used in which the control amount for each input value is inferred and calculated in advance and written into the ROM of the heat retention control device 32. FIG. 17 shows the inference result of the total number of combinations of the membership function conditional part. For example, room temperature (K) = 30°C, lid opening time (t) = 1
In the case of 5 seconds, the lid heating element 7 is energized for 6 minutes after the lid is closed. Further, when the room temperature (K) is 10° C. and the lid opening time (t) is 2 minutes, the lid heating element 7 is energized for 16 minutes and 42 seconds after the lid is closed.

In this embodiment, four lid heating element energizing time zones have been explained, but if the performance such as the capacity of the microcomputer allows, the lid heating element energizing time zone can be created with a longer energizing time and a finer energizing time increments. Needless to say, the present invention can be applied to. In addition, the control amount was determined using a total of four control laws based on two types of fuzzy labels related to room temperature and three types of fuzzy labels related to lid opening time, but if the detection accuracy of the room temperature detector 30 is not good, the control law We need to increase the number. The number of control laws and the number of fuzzy labels are desirably set based on the accuracy of the room temperature detector 30 and the number of energizing time zones of the lid heating element 7 (control resolution).

Here, even with the so-called real-time inference method in which the control amount is calculated every 1 second cycle of the lid opening time using the Min-Max-center of gravity method, if the fuzzy variables and control law of this embodiment are applied, the same result can be obtained. Needless to say, it can be effective.

Therefore, when the lid 6 is opened during heat retention, the time during which the lid heating element 7 is energized after the lid is closed is divided into multiple sections, and the room temperature and the lid are detected by the room temperature detector 30 and the lid opening/closing detector 31. By determining the energization time to the lid heating element 7 after the lid is closed using fuzzy reasoning, it is possible to suppress the drop in the surface temperature of the rice due to opening and closing the lid in a short time when keeping the rice warm. Deterioration can be suppressed.

[Fourth Embodiment] FIG. 18 is a functional block diagram of a rice cooker showing a fourth embodiment of the present invention, and FIG. 19-A is a diagram showing a temperature rise model and ideal temperature curve of the contents of this embodiment. , FIG. 19-B is a diagram also showing the ideal temperature rise value, FIG.
9-C is a diagram similarly showing changes in the manipulated variable, where (a) is the case of trial control and (b) is the case of relay control.

The rice cooker of this embodiment includes a heating device 1 that heats rice to boil it into porridge, a content temperature detector 2 that indirectly detects the temperature of the content, and the content temperature detector In order to prevent the porridge from boiling over, based on the output information from 2, the heating device 1 adjusts the temperature of the contents according to the amount of temperature change over a certain period of time and the difference from the ideal temperature of the contents at the time of temperature detection.
and a porridge heating control device 40 that infers and determines the heating amount of the rice porridge.

The porridge heating control device 40, as shown in FIG. 18, includes a temperature gradient calculating means 41 for calculating the temperature gradient within a certain period of time from the temperature reached after a certain period of time based on the output signal of the content temperature detector 2; A detected temperature difference calculating means 42 that calculates the difference between the reached temperature and the ideal temperature at that point, and a temperature rise calculator that uses the temperature gradient and the detected temperature difference as input factors to predict the temperature rise curve of the contents using these two input factors. The prediction means 43 infers and determines the optimal heating amount within the next predetermined time, that is, the energization time or electric energy of the heating device 1 from among the plurality of classifications for the heating amount of the heating device 1 in order to raise the temperature to the predicted temperature. Heating amount determining means 4
4.

Note that the other structures are the same as in the second embodiment.

In the above configuration, when the CPU 17 confirms that the preheating time has ended, the CPU 17 moves to a boiling detection sequence, and inputs and stores the output information of the thermistor 2.

[0088] Temperature detected by the thermistor after a predetermined period of time has elapsed;
Calculate the temperature gradient from the previous stored temperature. Also, calculate the difference from the ideal temperature at that point. Based on these two factors, the operation amount for the next predetermined time is referred to from the data ROM 19, and the time for energizing the heating device 1 is determined. Thereafter, the above operation is repeated in the same manner until a predetermined time.

Now, the thermistor temperature at a certain point is 41.
Assuming that the temperature rise for a predetermined time is 0.7°C at 2°C and the ideal temperature at that time is 43°C, the next manipulated variable will be 47/60 (78%) according to the data ROM 19.

Next, when the temperature after a predetermined period of time is 47°C,
If the ideal temperature is 46℃, the next manipulated variable is 34℃.
/60 (57%). In other words, the temperature of the contents rose rapidly and exceeded the ideal temperature, so control was performed to reduce the amount of operation to prevent bumping.

On the contrary, when the temperature rise is small, the amount of operation is large. In other words, the manipulated variable is as shown in FIG. 19-C. Here, in the figure, (a) shows the case where the heating device 1 is subjected to trial control, and (b) shows the case where the heating device 1 is subjected to relay control.

[0092] Therefore, when cooking rice porridge, it is possible to control the boiling point by adjusting the amount of operation in accordance with the temperature rise of the contents, making it possible to obtain delicious porridge without boiling over.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

[0094]

[Effects of the Invention] As is clear from the above description, according to claim 1 of the present invention, the temperature of the contents can be detected within a certain period of time after the start of cooking based on the output information from the contents temperature detector that indirectly detects the temperature of the contents. The temperature of the contents can be predicted using two input factors: the amount of temperature change and the temperature reached after a certain period of time.

[0095] Therefore, it is possible to infer and set the optimum preheating time for the heating device without being affected by water temperature, room temperature, or the temperature of the rice cooker, ensuring that the rice absorbs sufficient water and is uniform. Gelatinization can be achieved by heating and delicious rice can be cooked.

In claim 2, the content is determined by two input factors: a temperature gradient within a certain period of time based on the output information from the content temperature detector, and a difference between the temperature reached at the point in time when a certain period of time has elapsed, and the ideal temperature at that point. It is possible to predict the temperature rise curve of an object and determine the next heating amount for the heating device.

Therefore, if the volume of rice is small, it is possible to reduce the heating amount of the heating device before the temperature rises rapidly, and regardless of the volume of rice, the cooking time is stable and gelatinization is sufficiently performed. You can get delicious rice and prevent boiling over.

According to claim 3, when the lid is opened during heat retention, the room temperature and the lid opening time are determined by the room temperature detector and the lid opening/closing detector after the lid is closed, and the electricity is supplied to the heating element after the lid is closed. By determining the time using fuzzy reasoning, it is possible to suppress the drop in the surface temperature of the rice due to opening and closing of the lid during keeping warm in a short time, and to suppress deterioration of the kept warm rice.

According to claim 4, when cooking rice porridge, the amount of operation of the heating device can be adjusted according to the temperature rise of the contents to control the temperature up to boiling, so delicious porridge without boiling over can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of a rice cooker showing a first embodiment of the present invention.

FIG. 2 is also a control block diagram.

FIG. 3 is a schematic diagram of a rice cooker.

FIG. 4 is a diagram showing input/output specifications during fuzzy inference.

FIG. 5-A is a diagram showing a control law during fuzzy inference.

FIG. 5-B is a diagram showing a control law at the time of fuzzy inference.

FIG. 6-A is a diagram showing a membership function with respect to a detection level of a thermistor.

FIG. 6-B is a diagram showing a membership function with respect to the amount of temperature change.

FIG. 6-C is a diagram showing a membership function with respect to preheating control time.

FIG. 7 is a diagram showing a data table of output factors, that is, preheating control time, for input factors using the table lookup method.

FIG. 8 is a functional block diagram of a rice cooker showing a second embodiment of the present invention.

FIG. 9 is a diagram showing input/output specifications during fuzzy inference.

FIG. 10-A is a diagram showing a control law during fuzzy inference.

FIG. 10-B is a diagram similarly showing a control law during fuzzy inference.

FIG. 11-A is a diagram showing a membership function for the difference between the detected temperature and the ideal temperature.

FIG. 11-B is a diagram showing membership functions for temperature gradients.

FIG. 11-C is a diagram showing a membership function with respect to the amount of heating.

FIG. 12 is a diagram showing a data table of output factors, that is, amount of heating, for input factors using the table lookup method.

FIG. 13-A is a diagram showing a temperature rise model of the contents in this example.

FIG. 13-B is a diagram similarly showing an ideal temperature curve of the thermistor.

13-C] FIG. 13-C is a diagram similarly showing changes in the manipulated variable, in which (a) shows a case where the amount of rice is small, and (b) shows a case where the amount of rice is large.

FIG. 14 is a functional block diagram of a rice cooker showing a third embodiment of the present invention.

FIG. 15 is a diagram showing a control law during fuzzy inference.

FIG. 16-A is a diagram showing membership functions for room temperature.

FIG. 16-B is a diagram showing the membership function with respect to the lid opening time.

FIG. 16-C is a diagram showing the membership function with respect to the energization time of the lid heating element.

FIG. 17 is a diagram showing a data table of output factors for input factors using the table lookup method.

FIG. 18 is a functional block diagram of a rice cooker showing a fourth embodiment of the present invention.

FIG. 19-A is a diagram showing a temperature rise model and ideal temperature curve of the contents of this example.

FIG. 19-B is a diagram similarly showing ideal temperature rise values.

FIG. 19-C is a diagram similarly showing changes in the manipulated variable, where (a) shows the case of trial control and (b) shows the case of relay control.

20-A] FIG. 20-A is a diagram showing a temperature rise model of contents when conventional large-volume and small-capacity rice is cooked.

FIG. 20-B is a diagram similarly showing a temperature rise model of the thermistor.

FIG. 20-C is a diagram similarly showing changes in the manipulated variable, where (a) shows a case where the amount of rice is small, and (b) shows a case where the amount of rice is large.

FIG. 21-A is a diagram showing a temperature rise model of contents and thermistor in conventional rice porridge cooking.

21-B] FIG. 21-B is a diagram similarly showing changes in the manipulated variable, where (a) shows the case of trial control and (b) shows the case of relay control.

[Explanation of symbols]

1 Heating device 2 Contents temperature detector 3 Preheating control device 6 Rice cooker lid 7 Heating element 21 Heating control device 30 Room temperature detector 31 Lid open/close detector 32 Heat retention control device 40 Porridge heating control device

Claims (4)

[Claims] Claim 1: A heating device that preheats the rice to absorb water, a content temperature detector that indirectly detects the temperature of the content, and a system that allows the rice to absorb water based on output information from the content temperature detector. 1. A rice cooker comprising a preheating control device that infers and determines a preheating time based on a detected temperature and an amount of temperature change over a certain period of time in order to obtain uniform heating and gelatinization. [Claim 2] A heating device for heating and boiling rice;
a content temperature detector that indirectly detects the temperature of the content;
In order to control the time until the rice boils within a certain range of time based on the output information from the content temperature sensor, the temperature change amount over a certain period of time and the difference from the ideal temperature of the content at the time of temperature detection are used. 1. A rice cooker comprising: a heating control device that infers and determines the heating amount of the heating device according to the content of the rice cooker. [Claim 3] A heating element that heats the heated rice;
Based on a room temperature detector that detects room temperature, a lid opening/closing detector that detects opening/closing of the rice cooker lid, room temperature output information from the room temperature detector when the lid is opened, and lid opening time output information from the lid opening/closing detector. A rice cooker comprising: a heat retention control device that infers and determines the time period for which electricity is applied to the heating element so that the decreased surface temperature of the rice becomes the heat retention temperature. 4. A heating device that heats and boils rice to make porridge; a content temperature detector that indirectly detects the temperature of the content; and a content temperature detector that indirectly detects the temperature of the content. A porridge heating control device that infers and determines the heating amount of the heating device according to the temperature of the contents based on the amount of temperature change over a certain period of time and the difference from the ideal temperature of the contents at the time of temperature detection in order to prevent boiling over. A rice cooker characterized by being equipped with.