JP4029352B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker that reduces steam generated during rice cooking.

  Conventionally, the rice cooker which reduces the quantity of the vapor | steam which generate | occur | produces in an inner pot by controlling the temperature of the inner pot in a rice cooking process to 95 degreeC or more and less than a boiling point is proposed (for example, refer patent document 1). .

Japanese Patent Laid-Open No. 10-71072 (first page, FIG. 4)

By the way, after the rice is sufficiently absorbed in the preheating step, the rice surface components are dissolved in water by heating in the rice cooking step to form a so-called rice ball. This rice stick adheres to the rice surface and becomes a water retaining film. For this reason, even if it is the time when there is no water around the rice in the middle of cooking, the gelatinization of the rice is performed to the center of the rice while preventing excessive release of the water once sucked by the rice. Here, since the water level in the inner pot falls due to the evaporation of water in the rice cooking process, most of the rice balls are generated in the lower part of the inner pot.
However, the above-mentioned conventional rice cooker has a low heating temperature in the rice cooking process, so bubbles are not sufficiently transferred from the bottom of the inner pot or water convection, Cannot move enough to the top of the pan. As a result, a sufficient amount of water-retaining film is not formed around the rice in the upper part of the inner pot, resulting in hard and dry rice, and the lower part of the inner pot becomes soft and damp rice. It was.

  An object of this invention is to provide the rice cooker which solves such a problem and can reduce the vapor | steam which generate | occur | produced during rice cooking, without generating dispersion | variation in a taste.

The rice cooker according to the present invention includes an inner pot, a heating means for heating the inner pot, and a control means for controlling the heating means for each step of the preheating process, the rice cooking process, and the steaming process. In the first step of the first half of the process, the temperature of the inner pot is raised to the boiling temperature and maintained, and in the second step of the second half of the rice cooking process, the temperature of the inner pot is lowered below the boiling temperature to reduce the temperature of the inner pot. The content temperature is maintained at 98 ° C. or higher and lower than the boiling point .

If it is the rice cooker which concerns on this invention, since the temperature of the inner pot is raised and maintained by the control means at the 1st process of the first half of the rice cooking process, the movement of the bubble from the bottom of the inner pot In addition, water convection is sufficient. For this reason, rice balls generated in the lower part of the inner pot move smoothly to the upper part of the inner pot, and a sufficient amount of water retention film is formed around the rice in the upper part of the inner pot. And this water retaining film can be used to gelatinize the rice to the center of the rice while preventing excessive release of the water once sucked by the rice, so cook delicious rice even at the top of the inner pot It becomes possible.
Moreover, since the temperature of the inner pot is lowered below the boiling temperature and the content temperature of the inner pot is maintained at 98 ° C. or higher and lower than the boiling point by the control means in the second step in the latter half of the rice cooking process, The amount of steam generated in the pan can be reduced, and energy for water heating and evaporation can be reduced.

Hereinafter, a preferred embodiment of a rice cooker according to the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
1 is a cross-sectional view showing a configuration of a rice cooker according to Embodiment 1. FIG. FIG. 2 is a plan view showing the configuration of the rice cooker according to the first embodiment. 1 and 2, 1 is a rice cooker body having an upper opening, and 2 is a hinge portion 1 a provided at the rear upper part of the rice cooker body 1 so as to cover the upper opening of the rice cooker body 1 so as to be freely opened and closed. The attached lid 3 is an inner pot accommodated in the rice cooker body 1, 4 is an induction heating coil for electromagnetically heating the inner pot 3 provided in the rice cooker body 1, and 5 is an upper case 6 and lower It is a main body case of the rice cooker main body 1 including a case 7 and a coil base 8.

  An operation panel 9 such as a rice cooking switch or a reservation switch is provided on the upper front side of the upper case 6, and a warming body heater 10 made of a cord heater is attached to the outer surface side of the inner wall 6 a of the upper case 6. It has been. The power cord reel 11 is provided in the vertical direction from the upper case 6 to the lower case 7 on the rear side in the rice cooker body 1.

  In addition, an inner pot temperature sensor 12 that detects the temperature of the inner pot 3 in contact with the bottom of the inner pot 3 is provided at substantially the center of the coil base 8 of the main body case 5. Includes a ferrite 13 that is provided outside the induction heating coil 4 to prevent the magnetism leakage of the induction heating coil 4, and a control unit 14 that has a control board and the like and controls the operation of the rice cooker. It has. A cover case 15 includes a first upper plate 16 and a second upper plate 17. A first container 16 having an arc-shaped steam port 18a is detachably mounted on the first upper plate 16 in a recess 16a on the upper surface. Further, a cover member 19 is provided on the upper surface of the container 18. Inside the lid case 15, a lid temperature sensor 20 that contacts the bottom of the lid body 2 and detects the temperature of the lid body 2 is provided.

  The rice bowl 18 introduces rice balls and steam generated by the increase in the internal pressure of the inner pot 3 when boiling in the rice cooking process from an introduction cylinder communicating with the inner pot 3 through the steam hole of the inner lid. In addition, the steam and the steam are separated by a plurality of barriers on the way, and only the steam is discharged to the outside of the lid body 2 from the steam port 18a. The remaining rice balls are stored in the tank, and when boiling stops and the internal pressure of the inner pot 3 decreases, the rice balls are returned to the inner pot 3 from the return valve to prevent spillage.

  When cooking rice with the rice cooker according to the first embodiment configured as described above, first, the inner pot 3 containing a predetermined amount of rice and water is accommodated in the rice cooker body 1 and the lid 2 is closed. At this time, the bottom surface of the inner pot 3 and the upper surface of the inner pot temperature sensor 12 are in close contact. Next, when the rice cooker is turned on and a rice cooking key (not shown) on the operation panel 9 provided on the front side of the rice cooker body 1 is pressed, the control unit 14 provided in the rice cooker body 1 is guided. The heating coil 4 is energized, an eddy current is generated on the bottom surface of the inner pot 3, the inner pot 3 is heated, and the rice cooking process is started. During cooking, the inner pot temperature sensor 12 detects the temperature of the inner pot 3, and based on this detected temperature, the control unit 14 controls energization to the induction heating coil 4, and performs the preheating, rice cooking, and steaming steps. Run to cook the rice in the inner pot 3.

Next, each process of preheating, rice cooking, and steaming is demonstrated based on the flowchart of FIG. 3, and the graph of FIG.
In each of these steps, the control unit 14 controls the induction heating coil 4 to have an optimum heating power. First, in the preheating step (S100 in FIG. 3), water is sufficiently absorbed so that the shape of the rice does not collapse. For example, if the water temperature is from room temperature to about 60 ° C., the water content of rice is almost stable at about 30%. If the temperature is higher than this, the rice begins to boil and the taste is lowered, which is not preferable. Under the control of the control unit 14, the rice is allowed to absorb water while being heated appropriately by the induction heating coil 4, and the preheating step is performed for about 10 to 40 minutes depending on the state of the cooked rice. When selecting so that soft rice can be cooked, it is good to control by the control part 14 so that preheating time may be taken long.

  Next, it moves to the 1st rice cooking process (the 1st process of the first half of the rice cooking process: S101 of FIG. 3), under the control of the control part 14, raises a thermal power with the induction heating coil 4, and boils the temperature of the inner pot 3 The water in the inner pot 3 is boiled at a temperature. Depending on the amount of rice cooked, the shape of the inner pot 3 and the heating amount of the induction heating coil 4, the water in which the dissolved components of the rice surface are concentrated between about 5 minutes after the start of boiling (ie, rice ) Boil up from the lower part of the inner pot 3 toward the upper part.

  As shown in FIG. 4, the temperature of the contents of the inner pot 3 is different from the detected temperature of the inner pot temperature sensor 12 and the detected temperature of the lid temperature sensor 20. That is, the temperature of the contents (rice and water) of the inner pot 3 is lower than the detected temperature of the inner pot temperature sensor 12 and higher than the detected temperature of the lid temperature sensor 20. Further, the temperature change of the contents of the inner pot 3 is slower than the detected temperature change of the inner pot temperature sensor 12 and is faster than the detected temperature change of the lid temperature sensor 20.

  The correlation between the temperature of the contents of the inner pot 3 and the detected temperatures of the sensors 12 and 20 is detected by a prior experiment. Based on the detected correlation data, the control unit 14 detects that the detected value of the inner pot temperature sensor 12 and / or the lid temperature sensor 20 is equal to or higher than a predetermined temperature, or the inner pot temperature sensor 12 and / or Alternatively, when the time when the detected value of the lid temperature sensor 20 is equal to or higher than the predetermined temperature continues for a certain time or more, it is determined that a sufficient amount of rice cake has occurred, and the second rice cooking process (the second half of the rice cooking process) Step: Go to S102 in FIG.

  In the rice cooking second step, under the control of the control unit 14, the heating amount of the induction heating coil 4 is lowered so as to maintain a temperature at which steam generation due to boiling can be suppressed. In particular, in order to effectively suppress the generation of steam, it is desirable to maintain the temperature at 98 ° C. or higher and lower than the boiling point. At this point, there is no liquid water around the rice in the upper part of the inner pot 3, but since a sufficient amount of water retention film is formed, it gradually comes out from the lower part of the inner pot 3. By sucking most of the coming steam, it is possible to make a good-tasting rice without releasing a large amount of steam from the steam outlet 20a and without drying the surface of the rice.

  Thereafter, based on the data whose correlation has been confirmed by a prior experiment, the control unit 14 detects a state in which the output of each of the sensors 12 and 20 rapidly increases after a predetermined time has elapsed, and then the steaming process (FIG. 3 (S103). In the steaming step, the heating amount of the induction heating coil 4 is reduced under the control of the control unit 14 so that the water in the inner pot 3 is not boiled and the lower rice in the inner pot 3 is not burned.

As mentioned above, since the temperature of the contents of the inner pot 3 is raised to the boiling temperature and maintained by the control unit 14 in the first rice cooking process, the movement of bubbles from the bottom of the inner pot 3 and water The convection is sufficiently performed. For this reason, rice balls generated in the lower part in the inner pot 3 move smoothly to the upper part of the inner pot 3, and a sufficient amount of water retention film is also formed around the upper rice in the inner pot 3. And with this water retaining film, it is possible to gelatinize the rice to the center of the rice while preventing excessive release of the water once sucked by the rice, so cook delicious rice even in the upper part of the inner pot 3 It is possible to raise.
Moreover, since the temperature of the content of the inner pot 3 is lowered below the boiling temperature and maintained by the control unit 14 in the second rice cooking process, the amount of steam generated in the inner pot 3 can be reduced. Energy for water heating and evaporation can be reduced.

Embodiment 2. FIG.
Next, a rice cooker according to Embodiment 2 will be described. FIG. 5 is a cross-sectional view showing the configuration of the rice cooker according to the second embodiment. The second embodiment is different from the first embodiment shown in FIG. 1 in that a weight sensor 21 is provided under the inner pot 3. Other configurations are the same as or equivalent to those of the first embodiment. In addition, the same code | symbol is attached | subjected about the component which is the same as that of Embodiment 1, or equivalent, and the description is abbreviate | omitted.

  The weight sensor 21 is provided under the inner pot 3 and detects the weight of the contents (rice and water) of the inner pot 3. And in the control part 14, based on the detected value of this weight sensor 21, the transfer timing from the rice cooking 1st process (S101 of FIG. 3) to the rice cooking 2nd process (S102 of FIG. 3) is controlled. That is, in the first rice cooking process, the weight reduction of the contents of the inner pot 3 due to the generation of steam occurs after the water boils, so the control unit 14 is predetermined from the time when the detection value of the weight sensor 21 starts to change. After the elapse of time, it is determined that rice balls are sufficiently generated, and the process proceeds from the first rice cooking process to the second rice cooking process. Alternatively, when the ratio between the weight obtained from the detection value of the weight sensor 21 and the weight at the start of rice cooking exceeds a predetermined ratio, it is determined that rice balls are sufficiently generated, and rice cooking is performed from the first step of rice cooking. Shift to the second step.

  As described above, since the occurrence timing of the rice ball is determined based on the detection value of the weight sensor 21, a sufficient amount of water retention film is formed around the upper rice in the inner pot 3 by this rice wave. Until it is done, in the control part 14, the boiling heating of the rice cooking 1st process can be maintained. As a result, it is possible to gelatinize the rice to the center of the rice while preventing excessive release of the water once sucked by the rice, so that delicious rice can be added to the upper part of the inner pot 3 as well. It can be cooked.

Embodiment 3 FIG.
Next, a rice cooker according to Embodiment 3 will be described. FIG. 6 is a cross-sectional view showing the configuration of the rice cooker according to the third embodiment. The third embodiment is different from the first embodiment shown in FIG. 1 in that it is provided with a water level sensor (onset detecting means) 22 that is provided at the bottom of the lid 2 and detects the water level in the inner pot 3. Is a point. Other configurations are the same as or equivalent to those of the first embodiment. In addition, the same code | symbol is attached | subjected about the component which is the same as that of Embodiment 1, or equivalent, and the description is abbreviate | omitted.

  The water level sensor 22 includes a light irradiation unit 22 a that irradiates visible light toward the bottom surface of the inner pot 3 and a light receiving unit 22 b that receives light reflected by the water surface in the inner pot 3. And the control part 14 controls the transfer timing from the rice cooking 1st process (S101 of FIG. 3) to the rice cooking 2nd process (S102 of FIG. 3) based on the detected value of this water level sensor 22. FIG. That is, in the initial stage of the first rice cooking process, there is no rice crack yet, so the water level in the inner pot 3 does not change. For this reason, the time until the light emitted from the light irradiation unit 22a is received by the light receiving unit 22b is constant.

  After that, when the inside of the inner pot 3 is continuously heated by the induction heating coil 4, the rice surface component is dissolved in water, and the rice cracker that has become difficult to crack is suddenly near the upper edge of the inner pot 3. The water level rises up to the height of. In this case, the light emitted from the light irradiating unit 22a is reflected by a toroidal bubble and enters the light receiving unit 22b, so that the time until the emitted light is received is shortened. Thus, when the time until the emitted light from the water level sensor 22 is received changes (when it becomes shorter), the control unit 14 determines that the rice ball is sufficiently generated, and the first rice cooking It shifts from the process to the second cooking rice process.

  As described above, since the generation timing of the rice ball is determined based on the detection value of the water level sensor 22, a sufficient amount of water retention film is also formed around the upper rice in the inner pot 3 by the rice ball. Until then, the controller 14 can maintain boiling heating in the first step of cooking rice. As a result, it is possible to gelatinize the rice to the center of the rice while preventing excessive release of the water once sucked by the rice, so that delicious rice can be added to the upper part of the inner pot 3 as well. It can be cooked.

  Next, a modification of the present embodiment will be described with reference to FIG. As shown in FIG. 7, in this modified example, an infrared sensor 23 is provided at the entrance portion of the container 18 instead of the water level sensor 22, and the container 18 is connected to the infrared sensor 23. Detecting a beacon that enters The infrared sensor 23 is provided at one of the entrance portions of the container 18, and an infrared irradiation unit 23a that irradiates infrared rays, and the infrared light reception unit 23b that is provided at the other of the entrance portions of the container 18 and receives infrared rays. It has. And in the control part 14, based on the detection result of this infrared sensor 23, the transfer timing from the rice cooking 1st process (S101 of FIG. 3) to the rice cooking 2nd process (S102 of FIG. 3) is controlled. In other words, in the initial stage of the first rice cooking process, there is no rice crack yet, so there is no possibility that the rice crack will enter the container 18. For this reason, the infrared light emitted from the infrared irradiation unit 23a is received by the infrared light receiving unit 23b.

  After that, when the inside of the inner pot 3 is continuously heated by the induction heating coil 4, the rice surface component is dissolved in water, and the rice cracker that has become difficult to crack is suddenly near the upper edge of the inner pot 3. A part of the rice cake enters the container 18. In this case, the infrared light emitted from the infrared irradiation unit 23a is blocked by the large bubble that has entered the container 18, and does not enter the infrared light receiving unit 23b. As described above, when the infrared sensor 23 detects the blocking of the infrared light, the control unit 14 determines that the rice ball has sufficiently generated, and shifts from the first rice cooking process to the second rice cooking process.

  As described above, since the generation timing of the rice ball is determined based on the blocking of the infrared light by the infrared sensor 23, a sufficient amount of water is retained around the upper rice in the inner pot 3 by the rice ball. Until the film is formed, the controller 14 can maintain boiling heating in the first rice cooking process. As a result, it is possible to gelatinize the rice to the center of the rice while preventing excessive release of the water once sucked by the rice. It can be cooked.

The water level sensor 22 may irradiate light other than visible light, or may use ultrasonic waves. Similarly, the infrared sensor 23 may emit light other than infrared light. The arrangement of the infrared sensor 23 is not limited to the entrance of the container 18, and may be arranged anywhere as long as it can detect the rice bowl.
Further, instead of the water level sensor 22, a CCD camera may be arranged at the lower part of the lid body 2, and the state of the water surface in the inner pot 3 may be directly monitored by the CCD camera to detect the size.
Further, instead of the water level sensor 22, a microphone may be disposed in the lower part of the lid body 2, and a sound generated as a result of the generation of the rice cake in the inner pot 3 may be detected by the microphone to detect the rice cake. .

It is sectional drawing which shows the structure of the rice cooker which concerns on Embodiment 1. FIG. It is a top view which shows the structure of the rice cooker which concerns on Embodiment 1. FIG. It is a flowchart which shows control of the rice cooker which concerns on Embodiment 1. FIG. It is a graph which shows the time-dependent change of the temperature of the rice cooking process which concerns on Embodiment 1, and power consumption. It is sectional drawing which shows the structure of the rice cooker which concerns on Embodiment 2. FIG. It is sectional drawing which shows the structure of the rice cooker which concerns on Embodiment 3. It is sectional drawing which shows the structure of the rice bowl used for the rice cooker which concerns on Embodiment 3. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rice cooker main body, 2 ... Cover body, 3 ... Inner pan, 4 ... Induction heating coil, 5 ... Main body case, 6 ... Upper case, 7 ... Lower case, 8 ... Coil stand, 9 ... Operation panel, 10 ... Body Heater, 11 ... Power cord reel, 12 ... Inner pan temperature sensor, 13 ... Ferrite, 14 ... Control part, 15 ... Cover case, 16 ... First upper plate, 17 ... Second upper plate, 18 ... A container 18a ... Steam port, 19 ... Cover member, 20 ... Lid temperature sensor, 21 ... Weight sensor, 22 ... Water level sensor, 22a ... Light irradiation unit, 22b ... Light receiving unit, 23 ... Infrared sensor, 23a ... Infrared irradiation unit, 23b ... Infrared light receiver.

Claims (8)

Inner pot,
Heating means for heating the inner pot;
A control means for controlling the heating means for each of the preheating process, the rice cooking process and the steaming process;
The control means raises and maintains the temperature of the inner pot to the boiling temperature in the first step of the first half of the rice cooking process, and boils the temperature of the inner pot in the second step of the second half of the rice cooking process. A rice cooker characterized in that the temperature of the contents of the inner pot is maintained below 98 ° C. and below the boiling point by lowering the temperature below the temperature. A temperature detecting means for detecting the temperature of the contents of the inner pot;
The control means switches from the first step to the second step after a predetermined time has elapsed since the temperature detecting means has detected that the temperature of the contents of the inner pot has risen to the boiling temperature. The rice cooker according to claim 1. Comprising weight detection means for detecting the weight of the contents of the inner pot,
2. The rice cooker according to claim 1, wherein the control unit switches from the first step to the second step based on a detection value by the weight detection unit.   The control means switches from the first step to the second step when the ratio between the value detected by the weight detection means and the weight at the start of rice cooking exceeds a predetermined ratio. The rice cooker according to claim 3.   4. The rice cooker according to claim 3, wherein the control unit switches from the first step to the second step after a predetermined time has elapsed since the detection value by the weight detection unit started to change. Provided with a detecting device for detecting a tomb generated in the inner pot,
2. The rice cooker according to claim 1, wherein the control unit switches from the first step to the second step when the first detection unit detects the first step. 3.   The rice cooker according to claim 6, wherein the rice ball detecting means is a water level sensor that detects a water level in the inner pot.   The rice cooker according to claim 6, wherein the rice detector is a sensor that detects the entry of a rice cake into a rice container provided at an upper portion of the main body.

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