JPH01158913A - Electric rice cooker - Google Patents

Abstract

PURPOSE: To make a rice cooker obtainable optimum cooking performance without reset of cooking conditions even on changing cooking volume by automatically detaching the cooking volume and controlling the steam heating after finishing of cooking rice in the rice cooker at a base of the cooking volume. CONSTITUTION: A microcomputer makes a heater continue to heat with high electric power PH according to the heating time t1 , namely cooking volume, required to reach working point temperatures Ta, Tb of a sensor. Similarly, it maintains to boil at middle electric power PM according to the time t1 and controls electricity to turn on at low electric power PL on reaching the cooking finish temperature Td. These electric power values and heating time t3 are determined according to the time t1 . Then, it controls electricity to turn on at steam heating electric power PB, and the whole cooking process is finished when the microcomputer furthermore counts the time t6 .

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric rice cooker, and particularly to an electric rice cooker that can automatically perform uneven heating.

[Conventional technology]

When rice is cooked using this type of electric rice cooker, a non-automatic reset switch is used to control the predetermined cooking completion temperature.

In other words, this switch is attached to the outer bottom of the inner pot that stores the rice, and when the rice is cooked, it senses a predetermined temperature and automatically opens the contact, and at this point the rice cooking is complete. .

[Problem to be solved by the invention]

However, in such a conventional configuration, after rice cooking is completed and the switch is opened, power is not supplied to the inner pot, which causes the temperature of the cooked rice in the inner pot to drop and the free water remaining in the cooked rice to be blown away. However, there was a drawback in that it was not possible to supply enough heat for the gelatinization of rice starch to proceed.

[Means to solve the problem]

In view of the above-mentioned conventional situation, the present invention automatically detects the amount of cooked rice and controls the uneven heating of the rice in the container from the point where the cooking is completed based on the amount of cooked rice.

[Effect]

This invention controls uneven heating from the rice cooking completion point based on the amount of rice cooked, so the temperature of the cooked rice in the inner pot is maintained without decreasing, and the free water remaining in the cooked rice in the inner pot is blown off.
Optimal rice cooking performance can be obtained without having to reset the settings each time the amount of rice cooked changes, such as by supplying enough heat to advance the gelatinization of starch in rice.

〔Example〕

Two embodiments of the present invention will be described below with reference to FIGS. 1 to M13.

(1) is the electric rice cooker itself, and (2) is the inner pot that stores the rice.

(41 is a sensor with a built-in thermistor as a temperature detection device attached closely to the bottom wall of the inner pot (2), (5)
is the operation panel attached to the electric rice cooker body (1).

(6) is the rice cooking on/off switch provided on the panel (5), (7) is the rice porridge cooking on/off switch provided on the operation panel (5), and (8) is on the panel (5). (9) is the sensor (4).
), the operating point of which is adjusted by the microcomputer az, which will be described later.
1 (1 is a commercial power source for operating the electric heater (3).

αυ is a triac connected in series to the commercial power supply and heater (3), and turns on when the gate GK signal is input.
On the other hand, if no signal is input, it becomes off (blocked).

α2 is a rice cooking on/off switch (6) and a rice porridge cooking on/off switch (7), which function as cooking switching means.
), the order of heat generation intensity of the heater (3) according to the selected cooking is memorized, the rate of temperature rise is detected by the signal from the sensor (4), the selected cooking amount is determined, and the amount of cooking is adjusted to this amount. C! as a control device that controls the operating time of each stage of the heating procedure accordingly! P.T.I.

A microcomputer equipped with ROM and RAM.

The time is measured by counting the wave number of the commercial power supply α.

That is, in rice cooking, this microcomputer (L5) instructs the operation of the high heat power PH2, medium heat power, 1 low heat power Pu, and steam cooking power I'B in order, and on the other hand, in the rice porridge cooking, the high heat power PH and low heat power PL are activated in order. The command is issued, and the operation time of the heater (3) at each stage is controlled in the order of strength obtained through the sensor (4) by sending a signal to the gate G of the triac I. PM is the low heat power PL is the average power.

Note that the power control here uses the energization rate control method.
For example, when the energization rate is 100%, it is high flame power.

When it is 30-98%, it is set as medium heat power, and when it is 211% or less, it is set as low heat power.

In this configuration, in the case of rice cooking + 11 processes, the inner pot (
2) When rice, water, etc. are added to the rice cooker and the rice cooker/off switch (6) is turned on, the microcomputer az receives and receives the rice cooking command and sends a signal to the gate G of the triac aD. This turns on the triac αυ,
The heater (3) starts operating and heats the inner pot (2) with high flame electric power PH as shown in FIG. and.

When the temperature of the inner pot (2) rises and the detection signal of the sensor (4) reaches the operating point temperature Ta of the comparator (9), the comparator (9) sends a signal to the microcomputer 2, and the microcomputer 0 is turned off for commercial use. Start counting the wave number of power supply αG and set the operating point of comparator (9) at temperature Tl.
).

When the temperature of the inner pot (2) further increases and the temperature detected by the sensor (4) reaches the operating point temperature Tb of the comparator (9) again as shown by the solid line in Fig. 5, a signal from the comparator (9) causes the microcomputer to a2 is the heating time t1 required for the sensor (4) to reach the operating point temperature Ta*Tb
is determined from the counted number of wave numbers, and depending on the length of this time t1, that is, the amount of rice cooked, from this point on, the rice in the inner pot (2) boils as shown at point A of the cooked rice temperature shown by the one-dot chain line in Figure 5. (
The heating time t2 until the temperature starts to rise to about 9IL5°C is selected from the memory of FIG. 6, and the heater (3) is continued to be controlled at high power PH. and.

When the microcomputer υ uses a timer function to determine that the short time t2 has elapsed, it stops the high flame power PR control.

As shown in FIG. 7, a heater (3
) begins to be energized and controlled via triac aυ.

Keep it boiling without boiling over.

On the other hand, the rice cooking completion temperature should be changed depending on the amount of rice being cooked.2 For example, when cooking a large amount of rice, if the rice cooking completion temperature is not very high, proper charring will not be possible and there will be too much free water in the rice. The N8 microcomputer α2 is used to prevent starch gelatinization from progressing insufficiently, or when cooking a small amount of rice, it may overcook, causing too much free water in the cooked rice, and other negative effects. As shown in the characteristics of the figure, the next appropriate rice cooking completion temperature is selected according to the heating time t1, that is, the amount of rice cooked, and the operating point of the comparator (9) is changed to the selected rice cooking completion temperature. Medium heat power PM operation continues.

When the temperature detected by the sensor (4) exceeds the rice-cooking completion temperature (for example, temperature Td), the comparator (9) starts controlling the number of people power PL via the triac αV.

The power value of this low heat power PL and the heating time t with this power
3 should be determined according to the heating time t1, and by changing the low heat power PL and the heating time t3 for the heating time t1, that is, the amount of rice cooked, it is possible to avoid burning the rice and further remove excess free water in the cooked rice. From Figures 9 and 10, which were obtained through experiments to find the optimum value that does not cause the rice to become too dry or cause uneven cooking, the microcomputer az determines the optimum value according to the time tIK. The low heat power PLO power value and heating time t3 are selected. and.

After the microcomputer Q2 has counted the heating time t3 and the 2-low heat power PL operation has ended, it counts the time t4, and after counting this time, the heater (3) is turned on at the time t5.
energization control begins via the triac aD to the steaming power FB. When the heating time t5 is counted and the steaming/cooking power 'FB operation is completed, the microcomputer z further counts the time t6, thereby completing the entire rice cooking process, and the end is notified by a buzzer or the like.

On the other hand, if the contact between the sensor (4) and the inner pot (2) is poor, the temperature detected by the sensor (4) will not exceed the rice-cooking completion temperature (for example, temperature Td) and will drop during the 2-low heat power PL operation period. When the temperature detected by the sensor (4) is less than the reference temperature 70, the low heat power PL operation is activated by the medium heat power P.
A control program is prepared in advance and stored in the micro combicator υ to return to the M operation and to return to the low heat power PL if the power exceeds 5'rc due to this operation. Therefore, its operation is as follows. That is, microcomputer α
2 detects the rice cooking completion temperature and enters low heat power PL operation control for heating time t3, but during that time t3, the sensor (
4) The detected temperature is scanned to see if it is above or below a certain reference temperature 'rc, and the microcomputer 12 judges this based on the signal from the comparator (9), and if it is 2 or more, it changes the power to low heat PL or lowers it. In this case, the respective heaters (3) are controlled to medium heat power PM. Note that this reference temperature 're is the same temperature as the rice-cooking completion temperature, but is higher than that.

Although it is possible to select three low temperature settings, it is better to configure the system so that the microcomputer selects the appropriate reference temperature TC depending on the amount of rice to be cooked.
This significantly improves the stability of rice cooking regardless of the amount of rice cooked. Moreover, of course, if the reference temperature Tc f also serves as the rice cooking completion temperature, there is an advantage that the cost of the control circuit can be reduced.

Furthermore, in the case of boiling water or continuous rice cooking, for example, the temperature of the inner pot (2) is at least the operating point temperature T1 of the comparator (9) at the start of the rice cooking operation, and the temperature detected by the sensor (4) is also at least the temperature Ta. , then the comparator (9)
Although the next operating point temperature Tl) is reached, the heating time t1 is measured in a short time, which is inconvenient if the parameters of various rice cooking patterns are automatically determined at this time t1. The present invention further provides the following functions. That is.

Rice cooking starts when the rice cooker/off switch (6) is turned on, and at the time of this start, the temperature detected by the sensor (4) is already higher than the operating point temperature Ta of the comparator (9) and lower than the next operating point temperature Tl). If so, the microcomputer α2 receives a signal from the comparator (9) almost at the same time as the rice cooking cut-off switch (6) is turned on, and from this the microcomputer α2 determines the heating time to determine the amount of rice to be cooked. It is determined that the rice cooking pattern does not depend on t1, and a program suitable for this pattern is selected. That is,
When the microcomputer O2 detects the operating point temperature TI), the heater (3) is fully operated with high heat power PH for a preset heating time t2, and thereafter is operated with medium heat power PM until the rice cooking completion temperature Td is reached.

Then, when the water in the rice runs out and the rice reaches the cooking completion temperature Td, the microcomputer α2 starts the comparator (
9), and stops supplying the signal to the gate G of the trybook aD, thereby stopping the energization of the heater (3). Furthermore, the microcomputer (13 is the time t
After counting to 7, a 9 buzzer etc. will notify you that the rice cooking is complete. Note that this rice cooking pattern may be configured to select an appropriate pattern from among turns (9 normal rice cooking) without setting a new rice cooking pattern, and such a countermeasure may also be taken.

Boiled rice and continuous cooking are possible.

Also, if the thermistor in the sensor (4) is intermittent, add more time than the maximum cooking time under various conditions such as when the outside temperature is low, the water temperature is low, and the power supply is low. Since the first operating point temperature Tat-sensor (4) cannot detect the temperature even after time has elapsed, the microcomputer C12 uses this to trigger the triac (Ill.
Stop the signal supply to the heater (3) and stop the operation of the heater (3).

On the other hand, when cooking rice porridge, input rice into the inner pot (2) in the same way as when cooking rice, and turn on/off switch (7) for cooking rice porridge.
) is turned on, the microcomputer 0 receives the rice porridge command and sends a signal to the gate G of the triac I.

As a result, the try book (111) is turned on and the heater (3) starts operating to heat the inner pot (2) with high flame electric power PH as shown in FIG.

When the temperature of the inner pot (2) rises and the temperature detected by the sensor (4) reaches the operating point temperature Ta of the comparator (9), the comparator (91 microcomputer a'attc
Signal 1ctsD, the microcomputer az starts counting the wave number of the commercial power supply, and the comparator (
9) Set the operating point at temperature Tl). The inner pot (2) further rises in temperature, and the sensor (4) is turned on again as shown by the solid line in Figure 13.
) is the operating point temperature Tl) of the comparator (9)
When the sensor (4) reaches the operating point temperature T, the microcomputer aX5 receives a signal from the comparator (9).
The heating time t1 required to reach tt + Tl) is determined from the number of counts of the wave number, and from this point on, the cooked rice in the inner pot (2) becomes the
The heating time t2 until boiling starts as shown at point B shown in the dashed line in the figure is determined, and the heater (3) is continuously controlled to high flame power Pi.

Then, when the microcomputer C12 determines that the time t2 has elapsed using the timer function, it stops the high heat power PH control and low heat power P with the energization rate according to the heating time t1.
Switch to L control. Using this low heat power PL, cooking is started by constantly simmering with relatively weak heat, and continues for an optimal heating time t8 corresponding to the heating time t1.When the microcomputer a2 finishes counting this time, the rice porridge is cooked. Cooking is finished.

〔Effect of the invention〕

As explained above, according to the second invention, since the control is switched to the force inside the inner pot, the temperature of the cooked rice in the inner pot is maintained without decreasing, and the temperature of the cooked rice remaining in the inner pot is maintained. Optimal rice cooking performance can be obtained without having to reset the settings each time the amount of rice cooked changes, such as by being able to supply sufficient heat to remove free water and advance the gelatinization of rice starch.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional front view of the electric rice cooker according to the present invention, Fig. 2 is a front view of the operation panel of the above rice cooker, Fig. 9M3 is a control circuit diagram of the above rice cooker, and Figs. 4 and 5. 6-10 are characteristic diagrams of data stored in the microcomputer, Figure 11 is a rice-cooking characteristic diagram when the sensor's sensitivity is poor, and Figures 12 and 13 are respectively rice cooking characteristics diagrams. are rice cooking characteristic diagrams, respectively. (1) Main unit, (2) Inner pot, (3) Electric heater, (4) Sensor, (6) Rice cooker/off switch, (9) ...Comparator, αD
...TRIAC, α2...Microcomputer.

Claims (1)

[Claims] In an electric rice cooker equipped with a container that stores rice and an electric heater that heats the rice through the container, the rate of temperature increase according to the amount of rice cooked is detected, and the average power consumption of the unevenness process from the point of completion of rice cooking is determined. An electric rice cooker, characterized in that it is provided with a control circuit that determines the rate of increase in temperature based on the detected temperature rise rate and controls switching to low-heat power that is lower than the average power before rice cooking is completed.