JP2000229031A - Pressurized rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably boil tasty rice by reliably detecting dry-up such as water runs out. SOLUTION: In a pressurized rice cooker 1 having an inner pot 2, a main body 3 for housing the inner pot 2, a heating means (an induction heating coil 6) for heating the inner pot 2, a cover body 8 for blocking up an opening part of the inner pot 2 by being installed on the main body 3 so as to be openable/ closable and a pressure input means (a pressure adjuster 16) arranged in the cover body 8, a pressure detecting means (a pressure sensor 15) is arranged to detect pressure in the inner pot 2, and when detecting pressure by the pressure detecting means becomes a preset lower limit value, the heating means is is turned on, and when the detecting pressure becomes a preset upper limit value, the heating means is turned off. While, the fact that water in the inner pot 2 runs out is detected on the basis of a change in the detecting pressure by the pressure detecting means. This water running-out detection is judged, for example, by time required for a pressure change of a prescribed range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called steamless pressure cooker for cooking rice without emitting steam.

[0002]

2. Description of the Related Art This type of pressure cooker is used to cook rice without stickiness and without burning it.
When the temperature of the inner pot is detected by a temperature sensor such as a thermistor, and dry-up that water has run out is detected,
This stops the energization of the heater and shifts to steaming.

However, when dry-up is detected by the temperature sensor, the temperature rise is not remarkable due to problems such as poor adhesion between the temperature sensor and the heat-sensitive portion, and thus the temperature detected by the temperature sensor varies. There was a problem that would occur.

In Japanese Utility Model Publication No. 4-43150, a second temperature sensor (steam generation detecting means) for detecting generation of steam is provided separately from the first temperature sensor (pan temperature detecting means) for detecting the pot temperature. Pressure cooker provided with.

[0005] In this pressure cooker, after the generation of steam is detected by the second temperature sensor, the pot temperature is detected by the first temperature sensor when a predetermined time has elapsed. Then, the detected temperature is set as a reference temperature, and a temperature obtained by adding a predetermined temperature to the reference temperature is set as a dry-up determination condition.

[0006]

However, in the pressure cooker, as shown in FIG.
The temperature at the bottom of the inner pot rises to over 120 ° C. And
At point A where pressure control is performed and dry-up is determined, the temperature at the bottom of the pot is about 130 ° C. and only about 10 ° C. appears, so that reliable and stable detection cannot be performed.

[0007] Further, in the pressure cooker, convection of water is less likely to occur in the inner pot, and the inner pot is sufficiently heated, as compared with a general pressure cooker in which no pressure is applied to the inner pot. Because it is not possible, the rice at the bottom of the pot tends to absorb a lot of water. Therefore, when the rice near the bottom of the inner pot is absorbing a lot of water as described above, the pot temperature does not rise, and the rice in the other portions is dried up even when the rice is sufficiently cooked. There was a disadvantage that it could not be detected.

In view of the above, an object of the present invention is to make it possible to reliably detect dry-up when water has run out and to stably cook delicious rice.

[0009]

Means for Solving the Problems To solve the above problems, a pressure cooker according to the present invention comprises an inner pot, a main body for accommodating the inner pot, heating means for heating the inner pan, and In a pressure cooker having a lid that is openably attached and closes an opening of the inner pan and pressure input means provided on the lid, pressure sensing means for detecting pressure in the inner pan is provided. The heating means is turned on when the pressure detected by the pressure detecting means reaches a set lower limit, and the heating means is turned off when the pressure reaches a set upper limit, and based on a change in the pressure detected by the pressure detecting means, It is configured to detect that the water in the inner pot has run out.

According to the pressure cooker, the dry-up is detected not by the temperature of the inner pot but by the pressure which changes remarkably with time, as in the prior art, so that the detection performance is stable. Be certain with. In addition, since the inner pot can be sufficiently heated, it is possible to suppress the disadvantage that rice at the bottom of the pot absorbs too much water.

In the pressure cooker, it is preferable that the detection of the absence of water in the inner pot by the pressure detecting means is determined based on a time required for a pressure change in a predetermined range.

Here, the range is preferably from the lower limit to the next lower limit, or from the upper limit to the next upper limit. Or, the range is from the lower limit to the upper limit,
Alternatively, the upper limit may be set to the lower limit.

Alternatively, the detection of the absence of water in the inner pot by the pressure detecting means may be determined based on a pressure change within a predetermined time.

Further, a temperature detecting means for detecting the temperature of the inner pot is provided, and the dry-up is detected by either the temperature detected by the temperature detecting means or the pressure detected by the pressure detecting means. If the pressure does not increase or the pressure cannot be detected due to
It is preferable to be able to detect that water has run out due to a rise in temperature.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a steamless pressure cooker 1 of the present invention. The pressure cooker 1 generally includes an inner pot 2, a main body 3, an induction heating coil 6 serving as a heating means, a temperature sensor 7 for the inner pot 2, a lid 8, and a temperature sensor 1 for the lid 8.
0, cooling means 11, pressure sensor 1 as pressure detecting means
5. Consists of a pressure regulator 16 as pressure input means and a microcomputer 20 as control means.

In the present embodiment, the inner pot 2 is formed of a conductive material which is electromagnetically heated by eddy current.

The main body 3 has a bottomed cylindrical shape and includes a protective frame 5 made of a non-conductive material for accommodating the inner pot 2 inside a body 4. The induction heating coil 6 and the microcomputer 20 are arranged between the body 4 and the protection frame 5.

The induction heating coil 6 is disposed on the lower surface of the protection frame 5 and is used for heating the inner pot 2 by electromagnetic induction when a high-frequency current is applied.

The temperature sensor 7 detects the temperature of the inner pot 2 and is disposed at the bottom of the protective frame 5.
And outputs the temperature of the inner pan 2 to the microcomputer 20.

The lid 8 closes the openings of the inner pan 2 and the main body 3 so as to be openable. A heat radiating plate 12, a heater 13, and an inner lid 14 are provided on the inner pan 2 side. ing.
Inside the lid 8, a temperature sensor 10, a cooling unit 11, a pressure sensor 15, and a pressure regulator 16 which will be described later are provided.

The temperature sensor 10 detects the temperature of the upper portion of the inner pot 2 and detects the temperature of the rice to be cooked (rice temperature).
And outputs the detected temperature to the microcomputer 20.

The cooling means 11 serves to apply strong heating to the rice itself by lowering the pressure in the inner pot 2 during rice cooking, and to quickly return to the atmosphere at the end of rice cooking. It is constituted by.
This cooling means 11 cools the inside of the inner pot 2 through the heat radiating plate 12 and the inner lid 14 by supplying external air sucked from the combined portion of the lid 8 to the heat radiating plate 12. Then, the internal pressure is reduced.

The pressure sensor 15 detects the internal pressure of the inner pan 2, and is disposed on the hinge side of the lid 8 so that the detecting portion faces the inside of the inner pan 2. .

The pressure regulator 16 includes a cap 17 having an opening 17 a communicating with the inner pot 2, a pressure regulating ball 18 disposed to face the opening 17 a from above, and a drive of the pressure regulating ball 18. And a solenoid 19 as a means. The pressure regulating ball 18 is pressed by a plunger of a solenoid 19 before rice cooking or at the initial stage of rice cooking, and is retracted from the opening 17a. In addition, at the time of cooking rice, the opening 17a is closed by the weight of the ball 18 to increase the internal pressure of the inner pot 2. On the other hand, when the inner pressure of the inner pot 2 exceeds, for example, 1.3 atm, the inner pot 2 is closed. The steam is discharged to the outside so that the pressure adjusting ball 18 floats.

According to the stored program, the microcomputer 20 controls the preheating, the medium rice cooking, the rice cooking power control,
In addition, the rice cooking operation is performed by sequentially executing the steps of heat retention and the rice cooking operation, and the induction heating coil 6 and the pressure regulator 16 are controlled in accordance with input signals from the temperature sensor 7, the pressure sensor 15, and the like.

Specifically, as shown in FIG. 2, the microcomputer 20 determines that the temperature in the inner pan 2 reaches a predetermined temperature via the temperature sensor 10 disposed on the lid 8 during the rice cooking process. When it is determined, the pressure in the inner pot 2 is controlled via the pressure regulator 16 within the range of about 1.20 atm to 1.25 atm until all the water is absorbed by the rice. That is, when the lower limit value is 1.20 atm,
The induction heating coil 6 is energized (turned on), and the upper limit value of 1.
At 25 atm, the power supply to the induction heating coil 6 is stopped (turned off).

Further, in the present embodiment, in addition to the dry-up detection based on the same temperature as the conventional one, until the next time the induction heating coil 6 is turned on via the pressure sensor 15 (on → off →
The on-time (hunting width) is detected, and the dry-up in which the water in the inner pot 2 runs out depending on the time is detected. Here, the time until the next induction heating coil 6 is turned on varies depending on the amount of water remaining in the inner pot 2. That is, as shown in FIG. 3, when the amount of water is large, the amount of vaporization and the amount of liquefaction are large.
The time required for the internal pressure to rise to the upper limit and the time required to fall to the lower limit are fast. Conversely, when the amount of water is small, the amount of vaporization and the amount of liquefaction are small, so the time required to rise to the upper limit and the time required to fall to the lower limit are slow. Therefore, the dry-up can be detected by detecting the times t1, t2, t3,..., Tn required for that. In addition,
As shown in Table 1 below, the temperature at which pressure is applied to the inner pot 2 and the time as a criterion for determining dry-up differ depending on the rice cooking capacity.

[0028]

[Table 1]

Next, rice cooking control by the microcomputer 20 of the pressure rice cooker 1 will be described. First, the user stores the desired number of cups of rice and the amount of water required to cook the rice in the inner pot 2, sets the inner pot 2 on the main body 3, and then sets the desired rice after cooking. Set the hardness of rice and cooking time.

Then, as shown in FIG. 4, when rice cooking is started, first, in step S1, the microcomputer 20 starts energizing the induction heating coil 6, and the temperature of the inner pot 2 is reduced to about 55%.
Preheating is performed by adjusting the temperature so that it is within the range of 65 ° C to 65 ° C.

When a predetermined time has elapsed, step S
After 100% (full power) is supplied to the induction heating coil 6 in step 2, the rice cooking capacity is determined in step S3. Here, the determination of the rice cooking capacity is performed through the temperature sensor 7 for the inner pot 2 based on a gradient at which the temperature of the inner pot 2 rises.

Next, in step S4, a temperature at which pressure is applied into the inner pot 2 via the pressure regulator 16 and a time for determining that the dry-up has been performed are set according to the determined rice cooking capacity. That is, as shown in Table 1, when it is determined that the cooking rice volume is one cup, the pressure input temperature is set to 70.
When the dry-up judgment time is determined to be 2 minutes and 30 seconds at 2 ° C. and the cup is judged to be 2 cups. If the pressure input temperature is 80 ° C and the dry-up determination time is 1 minute and 55 seconds, and if it is determined to be 5 cups, the pressure input temperature is 85 ° C and the dry-up determination time is 1 minute and 40 seconds and 10 cups If it is determined that there is, the pressure input temperature is set to 95 ° C., and the dry-up determination time is set to 1 minute and 30 seconds.

Next, in step S5, the control waits until the rice temperature of the rice in the inner pot 2 detected via the temperature sensor 10 disposed on the lid 8 reaches the set threshold value. Is reached, in step S6, the solenoid 19 of the pressure regulator 16
Is operated to apply pressure into the inner pan 2.

Thereafter, in step S7, a pressure control process, which will be described later, is performed. If it is determined that the pressure control process has dried up, the pressure input by the pressure regulator 16 is canceled in step S8.

Then, in step S9, energization of the heater 13 disposed on the lid 8 is started, and steaming and dew-exposure are performed for a predetermined time, thereby finishing rice cooking. When the rice cooking is completed, the process shifts to a heat retaining process, similarly to a known rice cooker.

Next, the pressure control processing by the microcomputer 20 will be described. In this pressure control process, as shown in FIG.
It is detected via the pressure sensor 15 whether or not the pressure has reached 1.25 atm, which is the upper limit value of the control range.
After turning off (cutting off) the power supply to, the process proceeds to step S14.

On the other hand, if the upper limit has not been reached in step S10, the process proceeds to step S12, where the temperature of the inner pan 2 is set to the upper limit (150) via the temperature sensor 7 for the inner pan 2.
C. to 160.degree. C.). And when exceeding the upper limit, in step S13,
After the power supply to the induction heating coil 6 is turned off, the process proceeds to step S19, which will be described later, stops the built-in operating timer, and returns. That is, if the internal pressure of the inner pot 2 does not increase for some reason or the pressure cannot be detected by the pressure sensor 15, it is determined by the temperature detection that the water has run out due to the temperature increase as in the related art. And finish cooking rice. In addition, it is possible to prevent scorching of the rice. On the other hand, if the value does not exceed the upper limit in step S12, the process returns to step S10.

In step S14, the process waits until the pressure in the inner pan 2 reaches 1.20 atm, which is the lower limit of the control range. When the pressure reaches the lower limit, in step S15, it is determined whether or not the built-in timer is operating. Is detected. If the timer is operating, the process proceeds to step S16. If the timer is not operating, the process returns to step S10 after starting the timer in step S17.

In step S16, after detecting how many minutes have passed since the induction heating coil 6 was previously turned on by the operating timer, in step S18, it is determined whether or not the detected time exceeds the set time. Is detected. If it is determined that the set time has elapsed, the process proceeds to step S19, in which the timer is stopped and the process returns.

On the other hand, if it is determined in step S18 that the set time has not been exceeded, the process proceeds to step S20,
The power supply to the induction heating coil 6 is turned on, and Step S2
After resetting the timer at 1, the process returns to step S10.

Thus, in the pressure cooker 1 of the present invention,
In the pressure control process, the power supply to the induction heating coil 6 is turned on while the pressure in the inner pot 2 is being controlled via the pressure sensor 15, and then the power supply is turned off by reaching the upper limit value, and the lower limit value is reached. Thus, the dry-up is detected by the time (hunting width) required until the energization is turned on again. That is, unlike the conventional example, the dry-up is detected not by the temperature of the inner pot but by the pressure at which the change of the hunting width changes with time.
The detection is stable and reliable. In addition, since the inner pot 2 can be sufficiently heated, it is possible to suppress the disadvantage that rice at the bottom of the pot absorbs too much water. As a result, the rice to be cooked can be cooked stably and always in a desired state.

In the above-described embodiment, as shown in FIG. 3, the pressure control process is performed based on the pressure detected via the pressure sensor 15, and at the same time, the current supplied to the induction heating coil 6 is controlled based on the detected value of the pressure sensor 15. Dry-up was detected in the time required to turn on → off → on
As shown in (2), the dry-up may be detected based on the time required to turn off the power supply to the induction heating coil 6 from on to off.

Further, as shown in FIG.
The dry-up may be detected by the time required for turning on and off the induction heating coil 6 controlled via the control unit, or the dry-up may be detected by the time required for turning on and off as shown in FIG.

Further, in any of the above detection methods, the dry-up is detected based on the time required to change within a predetermined pressure range. However, as shown in FIG. After that, the dry-up may be detected based on the amount of change in pressure within a predetermined time.
As shown in FIG. 0, after the power supply to the induction heating coil 6 is turned on, the dry-up may be detected based on the amount of change in pressure within a predetermined time.

In all of the above detection methods, the detection start by the timer is set to the upper limit or the lower limit in the pressure control. However, any position and range between the upper limit and the lower limit may be set.

[0046]

As is clear from the above description, in the pressure cooker of the present invention, the dry-up is detected not by the temperature of the inner pot but by the pressure which changes with time remarkably, as in the conventional example. Therefore, dry-up can be reliably detected, and the stability of detection can be improved. In addition, since the inner pot can be sufficiently heated, it is possible to suppress the disadvantage that rice at the bottom of the pot absorbs too much water. as a result,
The rice cooked over the entire inner pot can be cooked stably and always in the desired condition.

[Brief description of the drawings]

FIG. 1 is a schematic view of a pressure cooker of the present invention.

FIG. 2 is a graph showing changes in rice temperature, inner pot, and pressure by the pressure cooker of the present invention.

FIG. 3 is a graph showing dry-up detection of the present invention.

FIG. 4 is a flowchart showing control by the microcomputer of the pressure cooker.

FIG. 5 is a flowchart illustrating a pressure control process of FIG. 4;

FIG. 6 is a graph showing a modification of FIG. 3;

FIG. 7 is a graph showing another modification of FIG. 3;

FIG. 8 is a graph showing another modification of FIG. 3;

FIG. 9 is a graph showing another modification of FIG. 3;

FIG. 10 is a graph showing another modification of FIG. 3;

[Explanation of symbols]

1 ... pressure cooker, 2 ... inner pot, 3 ... body, 4 ... body, 5 ...
Protection frame, 6: induction heating coil (heating means), 7: temperature sensor, 8: lid, 10: temperature sensor, 11: cooling means,
12: heat sink, 13: heater, 14: inner lid, 15: pressure sensor (pressure detecting means), 16: pressure regulator (pressure input means), 18: pressure regulating ball, 19: solenoid, 20: microcomputer.

Claims (6)

[Claims] An inner pan, a main body for accommodating the inner pan, heating means for heating the inner pan, a lid body openably and closably attached to the main body, and closing an opening of the inner pan. Pressure cooker provided with a pressure input means provided on the lid, provided with pressure detection means for detecting the pressure in the inner pot, when the pressure detected by the pressure detection means reaches a set lower limit, the heating means On, while turning off the heating means when it reaches the set upper limit, based on a change in the pressure detected by the pressure detection means, based on the change in the pressure in the inner pot, it is characterized by detecting that the water in the inner pot has run out. Pressure cooker. 2. The pressure cooker according to claim 1, wherein the detection of the absence of water in the inner pot by the pressure detecting means is determined based on a time required for a pressure change in a predetermined range. 3. The pressure cooker according to claim 2, wherein the range is from the lower limit to the next lower limit or from the upper limit to the next upper limit. 4. The pressure cooker according to claim 2, wherein the range is from the lower limit to the upper limit or from the upper limit to the lower limit. 5. The pressure cooker according to claim 1, wherein the detection of the absence of water in the inner pot by the pressure detecting means is determined based on a pressure change within a predetermined time. 6. A temperature detecting means for detecting a temperature of the inner pot, and a temperature detected by the temperature detecting means, or
The pressure cooker according to any one of claims 1 to 5, wherein the dry-up is detected by any one of the pressures detected by the pressure detecting means.