JP3420962B2 - Pressure cooker - Google Patents

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 type pressure cooker for cooking rice without producing steam.

[0002]

2. Description of the Related Art This type of pressure cooker is designed to cook rice without making it sticky and non-sticky.
When the temperature of the inner pot is detected by a temperature sensor such as a thermistor and the dry-up that the water has run out is detected,
The energization to the heater is stopped, and the process shifts to steaming.

However, in the case of detecting the dry-up by the temperature sensor, the temperature rise is not remarkable due to a problem such as poor adhesion between the temperature sensor and the heat-sensitive section, so that the temperature detected by the temperature sensor varies. There was a problem that it would occur.

Therefore, in Japanese Utility Model Publication No. 4-43150, in addition to the first temperature sensor (pot temperature detecting means) for detecting the pot temperature, a second temperature sensor (steam generation detecting means) for detecting the generation of steam is provided. We provide a pressure rice cooker with.

In this pressure cooker, the pot temperature is detected by the first temperature sensor when a predetermined time has elapsed after the generation of steam was detected by the second temperature sensor. 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 rice cooker, as shown in FIG. 2, when the rice cook process is started,
The temperature of the bottom of the inner pot rises above 120 ° C. And
At point A, where pressure control is performed and it is determined that dry-up has occurred, the temperature at the bottom of the pot is about 130 ° C, and only a difference of about 10 ° C appears, so reliable and stable detection cannot be performed.

Further, the pressure cooker is less likely to cause convection of water in the inner pot and can heat the inner pot sufficiently as compared with a general pressure cooker in which pressure is not applied to the inner pot. The rice on the bottom of the pot can easily absorb a lot of water. Therefore, as mentioned above, when the rice near the bottom of the inner pot absorbs a lot of water, the pot temperature does not rise, and the rice in other parts should be dried up even if it is fully cooked. There was an inconvenience that it could not be detected.

[0008] Therefore, an object of the present invention is to make it possible to reliably detect the dry-up that the water is exhausted and to stably cook delicious rice.

[0009]

In order to solve the above-mentioned problems, a pressure cooker of the present invention comprises an inner pot, a main body for accommodating the inner pot, heating means for heating the inner pot, and a main body for the main body. In a pressure rice cooker equipped with a lid that is openably and closably attached to close the opening of the inner pot, and a pressure input means provided in the lid, pressure detecting means for detecting the pressure in the inner pot is provided. When the pressure detected by the pressure detecting unit reaches a set lower limit value, the heating unit is turned on, and when the detected pressure reaches the set upper limit value, the heating unit is turned off, while the heating unit is turned off based on a change in the pressure detected by the pressure detecting unit. It is configured to detect when the water in the inner pot has run out.

According to the pressure rice cooker, unlike the conventional example, the dry-up is detected not by the temperature of the inner pot but by the pressure whose change with time is remarkable, so that the detection performance is stable. With certainty. In addition, since the inner pot can be heated sufficiently, it is possible to suppress the inconvenience that the rice at the bottom of the pot absorbs too much water.

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

Here, it is preferable that the range is from the lower limit value to the next lower limit value or from the upper limit value to the next upper limit value. Alternatively, the range is from the lower limit to the upper limit,
Alternatively, the upper limit value may be set to the lower limit value.

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

Further, 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 rise or the pressure cannot be detected due to
It is preferable to be able to detect that the water has run out due to an increase in temperature.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION 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 rice cooker 1 is generally composed of an inner pot 2, a main body 3, an induction heating coil 6 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 detection means
5, a pressure regulator 16 which is a pressure input means, and a microcomputer 20 which is a control means.

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

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

The induction heating coil 6 is arranged on the lower surface of the protection frame 5 and is adapted to electromagnetically heat the inner pot 2 by applying a high frequency current.

The temperature sensor 7 detects the temperature of the inner pot 2 and is disposed at the bottom of the protective frame 5, and the detection portion at the tip of the temperature sensor 7 is passed through a through hole provided in the protective frame 5 to the inner pot 2.
The temperature of the inner pot 2 is output to the microcomputer 20 by bringing it into contact with the outer surface of the.

The lid 8 is configured to openably close the openings of the inner pot 2 and the main body 3, and a radiator plate 12, a heater 13 and an inner lid 14 are arranged on the inner pot 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 arranged.

The temperature sensor 10 detects the temperature of the upper portion of the inner pot 2 to detect the temperature of rice to be cooked (rice temperature).
Is detected and the detected temperature is output to the microcomputer 20.

The cooling means 11 is for heating the rice itself by lowering the pressure in the inner pot 2 during rice cooking and for quickly returning it to the atmosphere at the end of rice cooking. In this embodiment, a blower fan is used. It is composed 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 the external air sucked from the combined portion of the lid body 8 to the heat radiating plate 12. However, the internal pressure is reduced.

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

The pressure regulator 16 includes a cap 17 having an opening 17a communicating with the inner pot 2, a pressure regulating ball 18 arranged so as to face the opening 17a from above, and a driving of the pressure regulating ball 18. It is composed of a solenoid 19 which is a means. The pressure adjusting ball 18 is pressed by the plunger of the solenoid 19 before or during the initial rice cooking and is retracted from the opening 17a. When rice is cooked, the inner pressure of the inner pot 2 is increased by closing the opening 17a by the weight of the ball 18, and when the inner pressure of the inner pot 2 exceeds 1.3 atm, for example, The vapor is discharged to the outside so that the pressure regulating balls 18 are lifted up.

According to the stored program, the microcomputer 20 performs preheating, middle pappa, rice cooking power control, purging,
In addition, the rice heating operation is performed by sequentially performing each step of heat retention and temperature control, and the induction heating coil 6 and the pressure regulator 16 are controlled according to the input signals from the temperature sensor 7, the pressure sensor 15, and the like.

More specifically, as shown in FIG. 2, the microcomputer 20 determines that the temperature inside the inner pot 2 has reached a predetermined temperature through the temperature sensor 10 arranged on the lid 8 in the rice cooking process. If judged, the pressure in the inner pot 2 is controlled via the pressure regulator 16 within a range of about 1.20 atm to 1.25 atm until all the water is absorbed by the rice. That is, at the lower limit of 1.20 atm,
The induction heating coil 6 is energized (turned on), and the upper limit value is 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 by the same temperature as the conventional one, the induction heating coil 6 is turned on next through the pressure sensor 15 (on → off →
The time (on) is detected (hunting width), and the dry-up that the water in the inner pot 2 is exhausted is detected by the time. Here, the time until the induction heating coil 6 is turned on next time changes 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 it. In addition,
As shown in Table 1 below, the temperature at which pressure is applied to the inner pot 2 and the time that is the criterion for dry-up differ depending on the rice cooking capacity.

[0028]

[Table 1]

Next, the 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 in the main body 3, and then after the desired rice is cooked. Set the hardness of rice and the time it takes to cook.

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

When a predetermined time has passed, step S
In step 2, the induction heating coil 6 is energized by 100% (full power), and then in step S3, the capacity of cooked rice is determined. Here, the determination of the rice cooking capacity is performed through the temperature sensor 7 for the inner pot 2 and the gradient of the temperature rise of the inner pot 2.

Then, in step S4, the temperature at which the pressure is applied to the inner pot 2 via the pressure regulator 16 and the time for determining that the dry-up is performed are set according to the determined rice cooking capacity. That is, as shown in Table 1, when it is determined that the rice cooking capacity is 1 cup, the pressure input temperature is 70%.
If the dry-up determination time is 2 minutes and 30 seconds as ℃ and it is determined that it is 2 cups, the pressure input temperature is 76 ° C and the dry-up determination time is 2 minutes and 10 seconds as it is 3 cups. If the pressure input temperature is 80 ° C and the dry-up determination time is 1 minute 55 seconds and it is determined to be 5 cups, the pressure input temperature is 85 ° C and the dry-up determination time is 1 minute 40 seconds and 10 cups. If it is determined that the temperature is 95 ° C., the dry-up determination time is set to 1 minute and 30 seconds.

Next, in step S5, the temperature of the rice in the inner pot 2 detected by the temperature sensor 10 provided on the lid 8 is waited until the set threshold value is reached, and the threshold value is set. Is reached, in step S6, the solenoid 19 of the pressure regulator 16 is reached.
Is operated to apply pressure into the inner pot 2.

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

Next, in step S9, the heater 13 provided on the lid 8 is energized and steamed and dewed for a predetermined period of time to finish cooking rice. In addition, when the rice cooking is completed, the heat retaining process is performed as in the known rice cooker.

Next, the pressure control processing by the microcomputer 20 will be described. In this pressure control process, the microcomputer 20 first, in step S10, as shown in FIG.
It is detected via the pressure sensor 15 whether or not the pressure has reached the upper limit of the control range, 1.25 atm. If the pressure has reached the upper limit, the process proceeds to step S11 and the induction heating coil 6
After turning off (interrupting) the energization to, the process proceeds to step S14.

On the other hand, if it is determined in step S10 that the upper limit value has not been reached, the process proceeds to step S12, in which the temperature of the inner pot 2 reaches the upper limit value (150) via the temperature sensor 7 for the inner pot 2.
℃ ~ 160 ℃) is detected. If the upper limit is exceeded, in step S13,
After the induction heating coil 6 is de-energized, the process proceeds to step S19, which will be described later, and stops the built-in operating timer and returns. That is, if the internal pressure of the inner pot 2 does not rise or the pressure cannot be detected by the pressure sensor 15 for some reason, it is determined by the temperature detection that the water has disappeared due to the temperature rise, as in the conventional case. And finish cooking rice. Moreover, this can prevent the rice from burning. On the other hand, if the upper limit value is not exceeded in step S12, the process returns to step S10.

In step S14, the process waits until the pressure in the inner pot 2 reaches the lower limit value of the control range, 1.20 atm, and when it reaches the lower limit value, in step S15, it is determined whether or not the built-in timer is operating. To detect. Then, if the timer is operating, the process proceeds to step S16. If not, the timer is started in step S17, and then the process returns to step S10.

In step S16, it is detected by the timer in operation how many minutes have passed since the induction heating coil 6 was turned on before, and in step S18, whether the detected time exceeds the set time or not. To detect. When it is determined that the set time is exceeded, the process proceeds to step S19, 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,
Turn on the power supply to the induction heating coil 6, and step S2
After resetting the timer in step 1, the process returns to step S10.

As described above, in the pressure cooker 1 of the present invention,
In the pressure control process, while controlling the pressure inside the inner pot 2 via the pressure sensor 15, the induction heating coil 6 is energized, and then the energization is turned off by reaching the upper limit, and the lower limit is reached. The dry-up is detected by the time (hunting width) required to turn on the power again. That is, as in the conventional example, not the temperature of the inner pot, but the pressure that causes a significant change in the hunting width over time is used to detect dry-up.
The detection is stable and reliable. In addition, since the inner pot 2 can be sufficiently heated, it is possible to suppress the inconvenience that the rice at the bottom of the pot absorbs too much water. As a result, the cooked rice can be cooked stably and always in a delicious and desired state.

In the above embodiment, as shown in FIG. 3, pressure control processing is performed by the pressure detected by the pressure sensor 15, and at the same time, the induction heating coil 6 is energized by the detection value of the pressure sensor 15. The dry-up was detected in the time required to turn on → off → on, but Fig. 6
As shown in, the dry-up may be detected by the time required to turn off the power supply to the induction heating coil 6 → on → off.

Further, as shown in FIG. 7, the pressure sensor 15
The dry-up may be detected in the time required to turn on / off the induction heating coil 6 controlled via, or as shown in FIG. 8, the dry-up may be detected in the time required to turn on → off.

Further, in any of the above-mentioned detection methods, the dry-up is detected by the time required to change within the predetermined pressure range. However, as shown in FIG. 9, the induction heating coil 6 is deenergized. After that, the dry-up may be detected by the amount of change in pressure within a predetermined time.
As shown in 0, after the power supply to the induction heating coil 6 is turned on, the dry-up may be detected by the change amount of the pressure within a predetermined time.

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

[0046]

As is apparent from the above description, in the pressure rice cooker of the present invention, unlike the conventional example, the dry-up is detected not by the temperature of the inner pot but by the pressure that changes significantly with time. Therefore, it is possible to reliably detect the dry-up and improve the stability of the detection. In addition, since the inner pot can be heated sufficiently, it is possible to suppress the inconvenience that the 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 in a stable and always delicious desired state.

[Brief description of drawings]

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

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

5 is a flowchart showing the pressure control process of FIG.

FIG. 6 is a graph showing a modified example of FIG.

FIG. 7 is a graph showing another modified example of FIG.

FIG. 8 is a graph showing another modified example of FIG.

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

10 is a graph showing another modified example of FIG.

[Explanation of symbols]

1 ... Pressure cooker, 2 ... Inner pot, 3 ... Main body, 4 ... Body, 5 ...
Protective 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 detection means), 16 ... Pressure regulator (pressure input means), 18 ... Pressure regulating ball, 19 ... Solenoid, 20 ... Microcomputer.

Claims (6)

(57) [Claims] 1. An inner pot, a main body for accommodating the inner pot, heating means for heating the inner pot, a lid body which is openably and closably attached to the main body and closes an opening of the inner pot, In a pressure rice cooker equipped with a pressure feeding means provided in a lid, a pressure detecting means for detecting the pressure in the inner pot is provided, and the heating means is activated when the pressure detected by the pressure detecting means reaches a set lower limit value. On, and when the set upper limit value is reached, the heating means is turned off, while the fact that the water in the inner pot is exhausted is detected based on the change in the pressure detected by the pressure detection means. Pressure rice cooker. 2. The pressure rice cooker according to claim 1, wherein the detection of the absence of water in the inner pot by the pressure detecting means is made based on the time required for a pressure change within a predetermined range. 3. The pressure cooker according to claim 2, wherein the range is the lower limit value to the next lower limit value or the upper limit value to the next upper limit value. 4. The pressure cooker according to claim 2, wherein the range is the lower limit value to the upper limit value or the upper limit value to the lower limit value. 5. The pressure rice cooker according to claim 1, wherein the detection of the absence of water in the inner pot by the pressure detecting means is determined by a pressure change within a predetermined time. 6. A temperature detecting means for detecting the temperature of the inner pot is provided, and the temperature detected by the temperature detecting means, or
The pressure cooker according to any one of claims 1 to 5, wherein dry-up is detected by any of the pressures detected by the pressure detection means.