WO2014042195A1 - Rice cooker - Google Patents

Abstract

A rice cooker is provided with: an inner pot (11) for receiving therein a mixture of water and rice; a rice cooker body (10) for receiving the inner pot (11); a heating section (12) for heating the inner pot (11); a temperature detection section (14) for detecting the temperature of the inner port (11); a rice cooking control means (15a) for performing a rice cooking step, which includes at least a water absorption step and a heating step, by controlling the heating section (12) on the basis of temperature detected by the temperature detection section (14); a stirring mechanism (17, 18, 19, 19, 20, 21) for stirring the mixture of water and rice within the inner pot (11); and a stirring control means (15b) for controlling the stirring mechanism (17, 18, 19, 19, 20, 21) so that the stirring mechanism (17, 18, 19, 19, 20, 21) stirs the mixture of water and rice within the inner pot (11) immediately before the termination of the water absorption step. As a result of this configuration, the rice cooker can well cook delicious rice utilizing the stirring mechanism during rice cooking, the stirring mechanism stirring the mixture of water and rice within the inner pot.

Description

rice cooker

This invention relates to a rice cooker, and more particularly to a rice cooker having a function of stirring a mixture of rice and water by stirring.

As a conventional first rice cooker, it is provided on the side of the rice cooker body, and includes a water supply / drainage unit for supplying or draining water, and an operation unit for keying the specifications of the rice cooker on the outer surface of the rice cooker body. There is one that sharpens rice with a plurality of foldable blades (for example, see Japanese Patent Application Laid-Open No. 7-289424 (Patent Document 1)). Such rice cookers have been proposed for the purpose of saving labor in housework. Since the said rice cooker is equipped with the water supply / drainage part and the blade | wing which wash | cleans rice, it can replace the water before and after washing | cleaning rice, and can perform it from washing rice to rice cooking fully automatically.

Further, as a conventional second rice cooker, there is a rice cooker provided with a detachable stirrer provided on a lid, and a rice cooker is loosened by a stirrer after the steaming step in the rice cooking step is completed (for example, Japanese Patent Application Laid-Open No. 2008-2008). -278924 (patent document 2)). In the rice cooker, excess water can be efficiently discharged by the stirring member, and excess water after completion of rice cooking can be automatically discharged.

Japanese Patent Laid-Open No. 7-289424 JP 2008-278924 A

However, in the conventional first and second rice cookers, blades and stirring bodies are not used in the rice cooking process, and it has not been possible to cook delicious rice using the stirring function in the rice cooking process.

Moreover, in the said 1st, 2nd conventional rice cooker, the blade | wing and the stirring body are provided in order to reduce the effort before and behind rice cooking, and with respect to the rice cooker's original subject of cooking rice deliciously, The stirrer has no effect at all.

Therefore, an object of the present invention is to provide a rice cooker that can cook delicious rice using a stirring mechanism that stirs a mixture of rice and water in the inner pot during cooking.

In order to solve the above problems, the rice cooker of this invention is
An inner pot containing a mixture of rice and water;
A rice cooker body for storing the inner pot;
A heating unit for heating the inner pot;
A temperature detector for detecting the temperature of the inner pan;
A rice cooking control means for performing a rice cooking process including at least a water absorption process and a heating process by controlling the heating unit based on the detection temperature of the temperature detection unit,
A stirring mechanism for stirring the mixture of rice and water in the inner pot;
Stirring control means for controlling the stirring mechanism so as to stir the mixture of rice and water in the inner pot immediately before or after the end of the water absorption step is provided.

Here, “immediately before the end of the water absorption process” means that it is in the period near the end of the water supply process and before the end time, and “immediately after the end of the water absorption process” means near the end time of the water supply process and from the end time. It is in a later period.

According to the above configuration, the mixture of rice and water in the inner pot is stirred immediately before the end of the water absorption step (or immediately after the end) to give fluidity to the mixture, thereby mixing the rice and water in the inner pot. It becomes possible to distribute the whole starch substance uniformly. Therefore, by using the stirring mechanism during cooking of rice, it is possible to cook rice with good finish that is sweet but hardly burnt.

Moreover, in the rice cooker of one embodiment,
The water absorption step includes a first period in which the heating unit heats the inner pot so that the mixture of rice and water contained in the inner pot has a preset temperature, and the first period. Subsequently, the second period for holding the preset temperature,
The stirring control unit controls the stirring mechanism to stir the mixture of rice and water in the inner pot during the first period of the water absorption step.

According to the above embodiment, the mixture of rice and water in the inner pot is stirred by the stirring mechanism in the first period of the initial stage of the water absorption step, and fluidity is imparted to the mixture, so that the heat of the heating unit can be quickly increased. It can be transferred to the mixture of rice and water in the pan, and the time to reach the target water absorption process temperature is shortened.

Moreover, in the rice cooker of one embodiment,
The agitation control means controls the agitation mechanism to reduce the agitation amount less than the agitation amount in the first period of the water absorption step and less than the agitation amount immediately before or after the end of the water absorption step. Then, the mixture of rice and water in the inner pot is stirred during the second period of the water absorption step.

According to the above embodiment, during the second period of the water absorption step, the amount of stirring is less than the amount of stirring in the first period of the water absorption step, and the amount of stirring is less than the amount of stirring immediately before or just after the end of the water absorption step. By stirring the mixture of rice and water in the inner pot with a stirring mechanism and imparting fluidity to the mixture of rice and water, the temperature distribution in the inner pot can be kept more uniform during the second period. it can. Here, for example, when the stirring mechanism is composed of a stirring blade that rotates, the stirring amount is represented by (rotation speed of the stirring blade [rpm] × total stirring time during the period [s]) / period [s]. The

Moreover, in the rice cooker of one embodiment,
The water absorption step includes a first period in which the heating unit heats the inner pot so that the mixture of rice and water contained in the inner pot has a preset temperature, and the first period. Subsequently, the second period for holding the preset temperature,
The agitation control means controls the agitation mechanism to separate the agitation immediately before or after the end of the water absorption step during the second period of the water absorption step separately from the agitation immediately before or after the end of the water absorption step. Stir the mixture of rice and water in the inner pot with a stirring amount smaller than the amount.

According to the above embodiment, apart from the stirring just before the end of the water absorption process (or just after the end), the amount of stirring during the second period of the water absorption process is smaller than the amount of stirring immediately before or just after the end of the water absorption process. By stirring the mixture of rice and water in the pot with a stirring mechanism and imparting fluidity to the mixture of rice and water, the temperature distribution in the inner pot can be kept more uniform during the second period. Here, for example, when the stirring mechanism is composed of a stirring blade that rotates, the stirring amount is represented by (rotation speed of the stirring blade [rpm] × total stirring time during the period [s]) / period [s]. The

As is apparent from the above, according to the present invention, a rice cooker that can cook delicious rice well by using a stirring mechanism that stirs a mixture of rice and water in the inner pot during rice cooking is realized. Can do.

FIG. 1 is a schematic sectional view of a rice cooker according to a first embodiment of the present invention. FIG. 2 is a control block diagram of the rice cooker. Drawing 3 is a figure showing the temperature characteristic of each rice cooking process of the above-mentioned rice cooker. FIG. 4 is a diagram for explaining the relationship between the temperature characteristics and the stirring operation in the water absorption process of the rice cooker. Drawing 5A is a figure showing the test result of the above-mentioned rice cooker. FIG. 5B is a diagram showing sampling points of the above test. FIG. 6 is a schematic sectional view of a rice cooker according to the second embodiment of the present invention. FIG. 7 is a control block diagram of the rice cooker. FIG. 8 is a diagram showing temperature characteristics of each rice cooking process of the rice cooker. FIG. 9 is a diagram illustrating the relationship between the holding temperature of the rice cooker and the amount of reducing sugar. FIG. 10 is a diagram for explaining the relationship between the rice cooking temperature and the eluted solid content of the rice cooker. FIG. 11: is a schematic block diagram of the rice cooker of 3rd Embodiment of the heating cooker of this invention. FIG. 12 is a block diagram of the control device for the rice cooker. Drawing 13A is a figure showing each process and temperature history of the above-mentioned rice cooker. FIG. 13B is a diagram showing the operation and temperature history of the rotating body and stirring blades of the stirring mechanism of the rice cooker. FIG. 14A is a diagram showing the rotation speed of the stirring blade in the water absorption heating step. FIG. 14B is a diagram showing a duty ratio of an input voltage to the motor in the water absorption heating process. FIG. 15A is a diagram showing the rotation speed of the stirring blade in the water absorption heating process of the comparative example. FIG. 15B is a diagram illustrating a duty ratio of an input voltage to the motor in the water absorption heating process of the comparative example. FIG. 16: is a block diagram of the speed control part of the rice cooker of 4th Embodiment of the heating cooker of this invention. FIG. 17 is a diagram showing the rotation speed of the stirring blade in the water absorption heating process of the rice cooker.

Hereinafter, the rice cooker of the present invention will be described in detail with reference to the illustrated embodiments.

[First Embodiment]
FIG. 1: has shown the cross-sectional schematic diagram of the rice cooker of 1st Embodiment of this invention.

In FIG. 1, 10 is a rice cooker body, 11 is an inner pot for storing rice and water, 12 is an IH heater as an example of a heating unit for heating the inner pot 11, 13 is a power supply device, and 14 is an inner pot 11. A temperature sensor as an example of a temperature detection unit that detects temperature, 15 is a control device that controls the IH heater 12, the power supply device 13, and the like, 16 is a lid that can be opened and closed on the upper part of the inner pot 11, and 17 is an agitator A motor for driving blades, 18 is an inner lid fixed to the lid body 16, 19 and 19 are stirring blades directly connected to the inner lid 18, and 20 is a twin blade mechanism for developing and storing the stirring blades built in the inner lid 18. , 21 is a timing belt, 22 is a steam cylinder, and 23 is a mixture of rice and water.

The lid body 16 is attached to the rice cooker main body 10 so as to be opened and closed by a rotation mechanism 30.

In addition, it may replace with the IH heater 12 which heats the inner pot 11, and may use the hot plate type heater, or may utilize a microwave, and may heat the inner pot 11. FIG.

The inner pot 11 has a two-layer structure of outer stainless steel and inner aluminum, and the inner pot 11 is coated with fluorine. The inner pan 11 has a thickness of 3 mm. In addition, a scale line for cooking rice is marked on the inner wall of the inner pot 11. A user will hydrate to the scale line according to the number of cooking rice.

Then, the IH heater 12 disposed on the bottom surface of the rice cooker body 10 is energized to heat the inner pot 11 and cook rice. Adjustment of the temperature of the inner pot 11 is performed by controlling the IH heater 12 by the control device 15 based on the temperature detected by the temperature sensor 14 disposed at the bottom of the inner pot 11.

In addition, the twin blade mechanism 20 operates the rotation mechanism attached to the inner lid 18 holding the stirring blades 19, 19 via the timing belt 21 to rotate the inner lid 18. When the stirring blades 19, 19 are rotated downward and deployed, and the inner lid 18 is reversely rotated, the stirring blades 19, 19 rotate upward and are stored in a functional mechanism.

The above-described stirring blade driving motor 17, timing belt 21, twin blade mechanism 20, inner lid 18, and stirring blades 19, 19 constitute a stirring mechanism.

Also, the inner lid 18 is attached to the lid body 16 by a magnet so that the user can remove it, and can be removed and washed after cooking.

Also, the inner lid 18 seals the inner pot 11 with the lid 16 closed, and has a small hole on the surface of the inner lid 18 so that steam can be exhausted when boiling. The steam cylinder 22 of the lid body 16 exhausts excess steam during the boiling process.

FIG. 2 shows a control block diagram of the rice cooker, and the control device 15 includes a microcomputer and an input / output circuit and the like, and is an example of rice cooking control means for controlling the IH heater 12 based on the temperature detected by the temperature sensor 14. As a rice cooking control unit 15a, a stirring control unit 15b as an example of a stirring control means for controlling the operation of the stirring blades 19 and 19, and a timer 15c.

The control device 15 is stored in the microcomputer in advance based on an operation command input by the user via the operation panel 31 and a signal representing a detected temperature from the temperature sensor 14 that detects the temperature of the inner pot 11. By the rice cooking program, heating control of the IH heater 12 and operation control of the stirring blades 19 and 19 (shown in FIG. 1) are performed.

[Description of basic operation]
The basic operation | movement of the rice cooking of the common white rice which the rice cooker of the said embodiment performs is demonstrated using FIG.

In the graph shown in FIG. 3, the temperature change inside the inner pot 11 after pressing the rice cooking switch (not shown) is shown with time.

First, the lid 16 is opened by pressing the open / close button, and the inner pan 11 is removed from the rice cooker body 10. Put the amount of rice you want to cook in the inner pot 11. The unit of rice is “go” and “koji”. One go is equivalent to 150 g and 1 kaki is equivalent to 1500 g. Since this rice cooker has the agitating blades 19, after washing, the lid 16 is closed and the rice washing can be easily performed by pressing a rice washing switch (not shown). What is necessary is just to match the amount of water at the time of the rice washing with the cooking water level. After the rice washing, the water in the inner pot 11 is once drained, and predetermined water is reintroduced into the rice after the rice washing in the inner pot 11.

Set the inner pot 11 on the rice cooker body 10 and close the lid 16. When a rice cooker switch (not shown) at the top of the rice cooker body 10 is pressed, the IH heater 12 is energized in accordance with a command from the control device 15 to start rice cooking. Simultaneously with the start of rice cooking, temperature detection by the temperature sensor 14 is started, and the temperature management of each process in the rice cooking process is performed by the control device 15 based on the temperature detected by the temperature sensor 14.

The general rice cooking process includes a water absorption process for absorbing water into the rice and a heating process for promoting gelatinization of the rice. Furthermore, the heating process includes a cooking process up to boiling, a boiling maintenance process, and a steaming process in time order.

In general, the water absorption step is performed at a temperature lower than the temperature at which gelatinization of rice begins (about 60 ° C.).

The change in the water temperature of the inner pot 11 can be detected by a temperature sensor 14 that detects the temperature of the inner pot 11. When the temperature of the inner pot 11 is hunted at a certain constant temperature, the constant temperature is maintained by the cooperation of the temperature sensor 14 and the control device 15.

In the boiling maintenance step, the control device 15 controls the IH heater 12 so that the boiling can be continued for 15 minutes or more after the water reaches 100 ° C. At this time, the excess steam during boiling is exhausted to the outside through a small hole in the inner lid 18 and the steam cylinder 22 as necessary. And after boiling continues, there is almost no free water in the inner pot 11, and the rice is fully gelatinized rice.

In the subsequent steaming process, the IH heater 12 is controlled so that the temperature of the inner pot 11 does not become 90 ° C. or lower. At this stage, the water remaining slightly on the surface is absorbed by the rice and transformed into delicious rice. When this steaming process is completed, cooking is complete.

[Composition to give fluidity]
Here, the structure which provides fluidity | liquidity to the rice and water mixture of the inner pot 11 during rice cooking is demonstrated.

The fluidity imparted to the mixture of rice and water in the inner pot 11 is stored in advance as a control program in the rice cooker. The operation is determined by the user pressing the “fluid” rice cooking button on the operation panel 31 (shown in FIG. 2).

Detecting that the “fluidized” rice cooking button has been operated, the control device 15 reads the “fluidized” rice cooking program.

After that, the control device 15 executes the instruction code of the read rice cooking program “with fluidity”, and the whole rice cooking process is performed by controlling each part.

First, the control device 15 recognizes that a rice cooker is set based on detection data of a weight sensor (not shown). When the weight sensor detects a weight larger than the weight of the inner pot 11 itself, the control device 15 recognizes that the inner pot 11 containing rice and water is set in the rice cooker body 10.

Subsequently, the control device 15 energizes the IH heater 12 at the start of the first period of the water supply process. Here, the 1st period is the period which heats the inner pot 11 with the IH heater 12 so that the mixture of the rice and water accommodated in the inner pot 11 may become preset target temperature (for example, 59 degreeC). It is.

Next, the agitation control unit 15b of the control device 15 outputs a control signal to the agitation blade driving motor 17 so that the agitation blades 19 and 19 are normally rotated. The motor 17 rotates at a rotation speed given based on a control signal from the stirring control unit 15b. As a result, the inner lid 18 rotates forward. As the inner lid 18 rotates forward, the stirring blades 19 and 19 descend into the inner pot 11. When the stirring control unit 15b of the control device 15 confirms that the stirring blades 19 and 19 have been lowered, the stirring time is measured by the timer 15c so that the rotation operation is continued for the necessary time. The stirring control unit 15b operates the motor 17 intermittently based on the temperature data of the inner pot 11 from the temperature sensor 14 and the time measured by the timer 15c.

Once it is determined that the temperature in the inner pot 11 has exceeded 60 ° C., which is the upper limit temperature of the water absorption process, the motor 17 is temporarily stopped by the stirring control unit 15b.

Thereby, the stirring operation by the rotation of the stirring blades 19 and 19 is stopped, and the imparting of fluidity is stopped.

Thereafter, in the second period of the water absorption process, the motor 17 is rotated again by the stirring control unit 15b. Thereby, the forward rotation operation of the inner lid 18 is intermittently performed. Here, the second period is a period during which the mixture of rice and water stored in the inner pot 11 is maintained at the target temperature.

Next, when the timing of the timer 15c detects the end of the water absorption process, the inner lid 18 is reversely rotated. As the inner lid 18 rotates in the reverse direction, the stirring blades 19 and 19 are accommodated in the inner lid 18. And if it determines with the stirring blades 19 and 19 being accommodated in the inner cover 18, stirring operation will be completed.

During this time, the rice cooking control unit 15a repeats the on / off operation of the IH heater 12 so that the inner pot temperature recorded in the program is reached. Here, depending on the setting, the program for imparting fluidity may be an operation only in a certain temperature range, or may be repeated on and off separated by time.

FIG. 3 shows a stirrable operation section and a stirrable section where fluidity is imparted during the water absorption process.

In this embodiment, in the case of 3 rice cooking, a stirring operation is performed at a rotation speed of 150 rotations / minute or more in order to impart fluidity.

Next, referring to FIG. 4, a more preferable stirring operation obtained in the present invention will be described. In FIG. 4, the water absorption step is a first step of heating the inner pot 11 by the IH heater 12 so that the mixture of rice and water contained in the inner pot 11 reaches a preset target temperature (for example, 59 ° C.). A period and a second period for maintaining the target temperature.

FIG. 4 shows the internal temperature during the water absorption process shown in FIG. 3 and the actual on / off timing of the stirring operation. This rice cooker performs a water absorption process at a target temperature of 59 ° C. The purpose of this water absorption process is to promote sufficient water absorption in the rice and to increase the activity of the saccharifying enzyme to bring out more sweetness. In order to make rice delicious, it is ideal to maintain the temperature of the mixture of rice and water in the high activity temperature zone for as long as possible.

According to the rice cooker of the embodiment of the present invention, in the first period of the water absorption process, the heating operation starts and the stirring operation (repeating 5 seconds on and 10 seconds off) is started. By doing so, even if heating is started with a high heating power, the heat in the vicinity of the IH heater 12 can be quickly transferred to the entire inner pot 11. When it approaches the target temperature, it becomes an input with medium heat power. In the first period of this water absorption step, the stirring operation is repeated for 5 seconds on and 10 seconds off, so that the entire interior of the inner pot 11 reaches the target temperature of 59 ° C. 5 minutes after the start of heating. This is the initial stage (first period) of the water absorption process. Thus, it is possible to keep the entire mixture of rice and water in the inner pot 11 at a uniform temperature in a short time of 5 minutes by combining high heating power and stirring at the initial stage (first period) of the water absorption process. It becomes.

In the second period of the subsequent water absorption process, the entire inner pot 11 is once warmed in the same manner, and therefore, after reaching 59 ° C., neither active stirring nor heating is required, and the temperature in the inner pot 11 is Use the minimum amount of heating that does not drop. Here, as an example, 2 seconds on and 298 seconds off are repeated.

However, when 59 ° C. was kept for 15 minutes, a problem was found that the starch in the rice cooking liquid gradually settled although there was no temperature unevenness. In addition, it was found that there was a difference in the amount of glucose having a high temperature dependency, particularly at the bottom in the inner pot 11, although the temperature inside the inner pot 11 was kept constant. It was found that the eluted starch has a higher physical reaction probability than the starch in the rice grain and the reactivity of the glucose production reaction is higher. Therefore, the present inventor decided to add the stirring operation again in the third period (or immediately after the end of the water absorption process) immediately before the end of the water absorption process. In this embodiment, the stirring operation time immediately before the end of the water absorption step (third period) is about 10 seconds. In this third period, the IH heater 12 may be on or off.

In the rice cooker according to the embodiment of the present invention, the stirring operation is turned on for a total of 116 seconds in the 20 minutes of the water absorption process. Since it is the time corresponding to 10% of the whole, even if it repeats 6 seconds on 54 seconds off throughout the entire water absorption process, the amount of stirring operation is the same, but the temperature rise in the inner pot 11 is delayed. Therefore, it is preferable to stir the mixture of rice and water in the inner pot 11 as early as possible (first period) to impart fluidity. Furthermore, by imparting fluidity immediately before the end of the water absorption process (third period), it becomes possible to eliminate unevenness in the water absorption process and move to the next process in a uniform state as a whole.

In a conventional rice cooker that cannot provide fluidity, that is, a rice cooker that does not have a stirring function, when 59 ° C. is set as the target temperature of the water absorption process, the heating is based on the temperature detected by the temperature sensor. There was no method other than heating control in which the amount of heat was gradually added so that the temperature did not rise too much, and the internal temperature was gradually raised to approach the target temperature. For this reason, although the conventional rice cooker was made to reach | attain target temperature over about twice the time of the rice cooker of this invention, according to the rice cooker of this invention, in the water absorption process, it was about half the conventional time. It was possible to reach the target temperature and maintain the temperature distribution throughout the inner pot 11 uniformly.

Here, in order to make the temperature of the inner pot 11 uniform, it may be considered that the stirring is continued during the water absorption process to continue to impart fluidity to the mixture of rice and water in the inner pot 11. However, the present inventor, if the surface starch quality of rice is released more than necessary by rubbing rice soaked in water more than the limit, excessive starch quality may cause yellowing of rice or scorching of rice. I found that it causes. Therefore, it is preferable to impart the minimum fluidity to the mixture of rice and water in the inner pot 11 during the water absorption process.

[Experimental data]
FIG. 5A compares the measurement results when the stirring operation is performed immediately before the end of the water absorption process (with stirring) and when the stirring operation is not performed immediately before the end of the water absorption process (without stirring) in the rice cooker according to the embodiment of the present invention. Is. In this measurement, intermittent stirring for 5 minutes in the initial stage of the water absorption process is performed. In FIG. 5A, the vertical axis of the left graph represents the amount of glucose [mg / 100 g dried cooked rice].

Glucose is one of the sugars that increase during cooking, and is said to represent the sweetness of rice. It can be seen whether the glucose and the eluted starch produced during the water absorption process are evenly dispersed, that is, the rice has no unevenness in taste and texture.

In this experiment, 20 g samples were collected from each of three cooked rices, 20 g each, and each glucose amount was measured to obtain an average value. The sampling points are the center surface, the end surface and the center bottom when the cooked rice is viewed from above.

The sampling points are shown in FIG. 5B. In FIG. 5B, A is the center of the surface of the rice in the inner pan 11, B is the surface end, and C is the bottom center.

The experimental results are shown in [Table 1]. [Table 1] As shown in Table 1, by stirring for 10 seconds immediately before the end of the water absorption step, the coefficient of variation of 15% or more in a conventional rice cooker that cannot impart fluidity can be reduced to about 2%.

Thus, it was confirmed that the distribution variation of the amount of rice curl course could be greatly improved by imparting fluidity to the mixture of rice and water in the inner pot 11 immediately before the end of the water absorption process of the rice cooker. . The yellowing of the rice is clearly reduced when the stirring is applied for 10 seconds immediately before the end of the water absorption process, compared with the case where the stirring is not applied.

As described above, the rice cooker according to the present invention can cook delicious rice without unevenness by imparting fluidity to the mixture of rice and water in the inner pot 11 immediately before the end of the water absorption process.

According to the rice cooker of the said structure, the starch of the whole mixture of the rice and water in the inner pot 11 is provided by stirring the mixture of the rice and water in the inner pot 11 just before completion | finish of a water absorption process, and providing fluidity | liquidity. The quality can be evenly distributed, and delicious and uniform rice can be cooked. Therefore, by using the stirring mechanism during cooking of rice, it is possible to cook rice with good finish that is sweet but hardly burnt.

In this embodiment, the mixture of rice and water in the inner pot 11 is stirred immediately before the end of the water absorption step, but immediately after the end of the water absorption step, that is, at the initial stage when the temperature of the next cooking step has hardly increased. The mixture of rice and water in the inner pot may be stirred.

In addition, the mixture of rice and water in the inner pot 11 is stirred by the stirring blades 19 and 19 in the first period of the initial stage of the water absorption process to impart fluidity to the mixture, so that the heat of the IH heater 12 can be quickly increased. It can be made to transfer to the mixture side of the rice and water in the inner pot 11, and the arrival time to the target water absorption process temperature can be shortened. Thereby, rice cooking time can be shortened.

In addition to the agitation just before the end of the water absorption step (third period), the amount of agitation during the first period of the water absorption step ((the number of revolutions of the stirring blade [rpm] × the total agitation time during the first period [s ]) / Stirring amount less than the first period [s]) and just before the end of the water absorption process (third period) ((stirring blade speed [rpm] × total stirring time during the third period) [s]) / A mixture of rice and water in the inner pot 11 is stirred by the stirring blades 19 and 19 during the second period of the water absorption process with a smaller amount of stirring than the third period [s]). By imparting fluidity to the water mixture, the temperature distribution in the inner pot 11 can be kept more uniform during the second period.

In the above embodiment, the stirring mechanism is constituted by the motor 17 for driving the stirring blade, the timing belt 21, the twin blade mechanism 20, the inner lid 18, and the stirring blades 19 and 19. However, the stirring mechanism is not limited to this, and the inner pot You may apply this invention to the rice cooker provided with the stirring mechanism etc. which used the stirring blade etc. which were provided in the inner bottom face.

In the above embodiment, the stirring blades 19 and 19 as the stirring mechanism are normally rotated in one direction during the stirring operation. However, the forward and reverse rotations of the stirring mechanism may be alternately performed during the stirring. In this case, a stirring mechanism capable of stirring both in the forward rotation and the reverse rotation is used.

[Second Embodiment]
FIG. 6: has shown the cross-sectional schematic diagram of the rice cooker of 2nd Embodiment of this invention.

In FIG. 6, 110 is a rice cooker body, 111 is an inner pot for storing rice and water, 112 is an IH heater as an example of a heating unit for heating the inner pot 111, 113 is a power supply device, and 114 is an inner pot 111. A temperature sensor for detecting temperature, a control device 115 for controlling the IH heater 112, the power supply device 113, and the like, 116 a lid body that can be opened and closed on the upper part of the inner pot 111, 117 a motor for driving a stirring blade, 118 Is an inner lid fixed to the lid 116, 119 and 119 are stirring blades directly connected to the inner lid 118, 120 is a twin blade mechanism for deploying and storing the stirring blades built in the inner lid 118, 121 is a timing belt, 122 Is a steam cylinder and 123 is a mixture of rice and water.

The lid 116 is attached to the rice cooker main body 110 so as to be opened and closed by a rotating mechanism 130.

In addition, it may replace with the IH heater 112 which heats the inner pot 111, and may heat the inner pot 111 using a hot plate type heater or using a microwave.

The inner pot 111 has a two-layer structure of outer stainless steel and inner aluminum, and the inner pot 111 is coated with fluorine. The inner pot 111 has a thickness of 3 mm. In addition, a scale line for cooking rice is marked on the inner wall of the inner pot 111. A user will hydrate to the scale line according to the number of cooking rice.

Then, the IH heater 112 disposed on the bottom surface of the rice cooker main body 110 is energized to heat the inner pot 111 and cook rice. Adjustment of the temperature of the inner pot 111 is performed by controlling the IH heater 112 by the control device 115 based on the detected temperature of the temperature sensor 114 disposed at the bottom of the inner pot 111.

In addition, the twin blade mechanism 120 operates the rotation mechanism attached to the inner lid 118 holding the stirring blades 119 and 119 via the timing belt 121 so that the inner lid 118 rotates. When the stirring blades 119 and 119 are rotated downward and deployed, and the inner lid 118 is reversely rotated, the stirring blades 119 and 119 are functional mechanisms that are rotated upward and stored.

The above-mentioned stirring blade driving motor 117, timing belt 121, twin blade mechanism 120, inner lid 118, and stirring blades 119, 119 constitute a stirring mechanism.

Also, the inner lid 118 is attached to the lid body 116 by a magnet so that the user can remove it, and it can be removed and washed after cooking.

Also, the inner lid 118 seals the inner pot 111 with the lid 116 closed, and has a small hole on the surface of the inner lid 118 so that steam can be exhausted when boiling. The steam cylinder 122 of the lid 116 exhausts excess steam during the boiling process.

FIG. 7 shows a control block diagram of the rice cooker. The control device 115 includes a microcomputer and an input / output circuit and the like, and is an example of rice cooking control means for controlling the IH heater 112 based on the temperature detected by the temperature sensor 114. Rice cooking control unit 115a, stirring control unit 115b as an example of stirring control means for controlling the operation of stirring blades 119, 119, timer 115c, and rice cooking mode selection unit 115d as an example of rice cooking mode selection means Have. This rice cooking mode selection unit 115d selects either the standard rice cooking mode or the sweetness increasing rice cooking mode for cooking rice having a sweeter component than the standard rice cooking mode.

The control device 115 is stored in the microcomputer in advance based on an operation command input by the user via the operation panel 131 and a signal indicating a detected temperature from the temperature sensor 114 that detects the temperature of the inner pot 111. The heating control of the IH heater 112 and the operation control of the stirring blades 119 and 119 are performed by the rice cooking program.

[Description of basic operation]
The basic operation | movement of the rice cooking of the common white rice which the rice cooker of the said embodiment performs is demonstrated using FIG.

In the graph shown in FIG. 8, the temperature change inside the inner pot 111 after pressing the rice cooking switch (not shown) is shown with time. Further, the lower side of FIG. 8 shows a stirrable operation enabling section and a stirring operation disabling section for imparting fluidity during the water absorption process.

First, the lid 116 is opened by pressing the open / close button, and the inner pot 111 is taken out from the rice cooker body 110. Put the amount of rice you want to cook in the inner pot 111. The unit of rice is “go” and “koji”. One go is equivalent to 150 g and 1 kaki is equivalent to 1500 g. Since this rice cooker has the stirring blades 119, 119, after adding water, the lid 116 is closed, and a rice washing switch (not shown) can be pressed to easily wash the rice. What is necessary is just to match the amount of water at the time of the rice washing with the cooking water level. After the washing, the water in the inner pot 111 is once drained, and predetermined water is reintroduced into the rice after the washing in the inner pot 111.

Set the inner pot 111 on the rice cooker body 110 and close the lid 116. And the operation panel 131 in the upper part of the rice cooker main body 110 is operated, and either one of the standard rice cooking mode or the sweetness increasing rice cooking mode is selected.

Next, when a rice cooker switch (not shown) at the top of the rice cooker body 110 is pressed, the IH heater 112 is energized by the command of the control device 115 to start rice cooking. Simultaneously with the start of rice cooking, temperature detection by the temperature sensor 114 is started, and based on the temperature detected by the temperature sensor 114, the control device 115 performs temperature management of each process in the rice cooking process.

The general rice cooking process includes a water absorption process for absorbing water into the rice and a heating process for promoting gelatinization of the rice. Furthermore, the heating process includes a cooking process up to boiling, a boiling maintenance process, and a steaming process in time order.

In general, the water absorption step is performed at a temperature lower than the temperature at which gelatinization of rice begins (about 60 ° C.).

The change in the water temperature of the inner pot 111 can be detected by a temperature sensor 114 that detects the temperature of the inner pot 111. When the temperature of the inner pot 111 is hunted at a certain constant temperature, the constant temperature is maintained by the cooperation of the temperature sensor 114 and the control device 115.

Further, in the boiling maintenance step, the control device 115 controls the IH heater 112 so that the boiling can be continued for 15 minutes or more after the water reaches 100 ° C. At this time, the excess steam during boiling is exhausted to the outside through the small hole of the inner lid 118 and the steam cylinder 122 as necessary. And after boiling continues, there is almost no free water in the inner pot 111, and the rice is fully gelatinized rice.

In the subsequent steaming process, the IH heater 112 is controlled so that the temperature of the inner pot 111 does not become 90 ° C. or lower. At this stage, the water remaining slightly on the surface is absorbed by the rice and transformed into delicious rice. When this steaming process is completed, cooking is complete.

[Composition to give fluidity]
Here, the structure which provides fluidity | liquidity to the rice and water mixture of the inner pot 111 during rice cooking is demonstrated.

The provision of fluidity to the rice and water mixture in the inner pot 111 is stored in advance as a control program in the rice cooker. The operation is determined by the user pressing the “fluid” rice cooking button on the operation panel 131 (shown in FIG. 7).

When it is detected that the “cookable” rice cooking button has been operated, the control device 115 reads the “cookable” rice cooking program.

After that, the control device 115 executes the instruction code of the read rice cooking program “with fluidity”, and the whole rice cooking process is performed by controlling each part.

First, the control device 115 recognizes that a rice cooker is set based on detection data of a weight sensor (not shown). When the weight sensor detects a weight larger than the weight of the inner pot 111 itself, the control device 115 recognizes that the inner pot 111 containing rice and water is set in the rice cooker body 110.

Subsequently, the control device 115 energizes the IH heater 112 at the start of the first period of the water absorption process. Here, the 1st period is the period which heats the inner pot 111 with the IH heater 112 so that the mixture of the rice and water accommodated in the inner pot 111 may become preset target temperature (for example, 59 degreeC). It is.

Next, the stirring control unit 115b of the control device 115 outputs a control signal to the stirring blade driving motor 117 so that the stirring blades 119 and 119 rotate forward. The motor 117 rotates at a rotation speed given based on a control signal from the stirring control unit 115b. As a result, the inner lid 118 rotates forward. As the inner lid 118 rotates forward, the stirring blades 119 and 119 descend into the inner pot 111. When the stirring control unit 115b of the control device 115 confirms that the stirring blades 119 and 119 have been lowered, the stirring time is measured by the timer 115c so that the rotation operation is continued for the necessary time. The agitation control unit 115b operates the motor 117 intermittently based on the temperature data of the inner pot 111 from the temperature sensor 114 and the time measured by the timer 115c.

Once it is determined that the temperature in the inner pot 111 has exceeded 60 ° C., which is the upper limit temperature of the water absorption process, the motor 117 is temporarily stopped by the stirring control unit 115b.

Thereby, the stirring operation by the rotation of the stirring blades 119 and 119 is stopped and the fluidity is stopped.

Thereafter, in the second period of the water absorption process, the motor 117 is rotated again by the stirring control unit 115b. Thereby, the forward rotation operation of the inner lid 118 is intermittently performed. Here, the second period is a period during which the mixture of rice and water stored in the inner pot 111 is maintained at the target temperature.

Next, when the timer 115c detects the end of the water absorption process, the inner lid 118 rotates in the reverse direction. As the inner lid 118 rotates backward, the stirring blades 119 and 119 are housed in the inner lid 118. When it is determined that the stirring blades 119 and 119 are accommodated in the inner lid 118, the stirring operation is completed.

During this period, the rice cooking control unit 115a repeats the on / off operation of the IH heater 112 so that the inner pot temperature recorded in the program is reached. Here, depending on the setting, the program for imparting fluidity may be an operation only in a certain temperature range, or may be repeated on and off separated by time.

Next, the heating control of the rice cooker according to the embodiment of the present invention will be described using the graphs of FIGS. 9 to 10.

FIG. 9 shows the relationship between the holding temperature and the amount of reducing sugar during the water absorption process. The holding time at this time is 14 minutes. This reducing sugar is one of the components produced when water is added to rice and heated, and it is said to be a component representing sweetness. The graph of FIG. 9 is a value obtained by analyzing 150 g of rice cooked to 100 ° C. after holding at each holding temperature for 14 minutes.

As is clear from the graph of FIG. 9, it can be seen that the higher the retention temperature, the more reducing sugar is produced.

Here, as a result of examining how the amount of reducing sugar changes when the holding time at a certain temperature is extended, when the holding time at 58 ° C. is extended from 14 minutes to 25 minutes, the amount of reducing sugar is about 36%. Increase was confirmed. In addition, when the retention time at 61 ° C. was extended from 14 minutes to 25 minutes, an increase in reducing sugar amount of about 26% could be confirmed.

Looking at the retention temperature and reducing sugar amount graph in FIG. 9, an increase in sweetness is expected by increasing the retention temperature, but in particular, only in the region with a small slope of 63 ° C. or less, the temperature is increased. However, it was found that the amount of reducing sugar can be expected to be increased by extending the time slightly.

Therefore, in order to cook delicious rice from which sweetness is extracted, especially at 63 ° C. or less, sweetness can be increased by extending the holding time.

Here, in order to increase the sweetness of rice, you may think that the holding temperature should be set higher. However, the present inventor, when the surface starch quality of the rice more than necessary is released into the water by rubbing the rice soaked in water more than the limit, etc., excessive starch quality may cause yellowing of the rice or burning of the rice I have found that it causes. Therefore, the necessary minimum holding temperature is preferable, and if the time is extended, the present invention has led to the invention that it is preferable to lower the temperature.

10 is a graph obtained by measuring the eluted solid content (mainly starch) transferred to the liquid side when the water temperature in the water absorption step is gradually increased. It is a graph obtained by measuring the elution solid content for each temperature when no flow is added at the water absorption step (without stirring) and when the flow is added (with stirring).

As is apparent from the graph of FIG. 10, there is no difference in the amount of elution between when the fluid is added and when it is not added up to 50 ° C. You can see that the minutes are increasing. Furthermore, when it exceeds 58 degreeC, it turns out that the difference of the case where a flow is not added at all in a water absorption process (without stirring) and the case where a flow is added (with stirring) becomes large.

This indicates that, when the temperature exceeds 50 ° C., the water absorption of the rice proceeds and the periphery of the rice becomes soft, so that the outflow of the eluted solids when fluidity is imparted increases.

In order to bring out the sweetness of the rice, the holding temperature in the water absorption process may be set higher, but on the other hand, if the eluted solid content increases too much, the texture of the rice will change.

Here, it is known that eluting solids to a certain extent will produce delicious rice, but if it is excessively eluted, it will be deposited at the bottom in the latter half of the rice cooking process, causing burning. Therefore, after 50 ° C., a sequence is required so that the minimum required amount of starch is eluted.

Therefore, when the sweetness increasing rice cooking mode is selected, as shown in FIG. 8, rice with increased sweetness can be obtained by extending the holding time while lowering the holding temperature than the standard rice cooking mode.

By doing this, it is possible to provide a sweetness increasing rice cooking mode that increases only sweetness with the same texture (starch elution amount) as in the standard rice cooking mode.

At this time, according to the rice cooker of the embodiment of the present invention, the stirring operation (repetition of 5 seconds on and 15 seconds off) is started at the same time as the heating of the water absorption process starts. The firepower at this time is strong. By doing so, even if heating is started with high thermal power, fluidity is imparted to the mixture of rice and water, so that the heat in the vicinity of the IH heater 112 can be quickly transferred to the whole. When the target temperature is approached, it becomes an input with medium heat power. Since the stirring operation is repeated for 5 seconds on and 15 seconds off, after 5 minutes from the start of heating, the entire inner pot 111 reaches around 60 ° C. of the target temperature. This is the initial stage of the water absorption process. By combining high heating power and stirring at the initial stage of this water absorption step, the inside of the inner pot 111 can be maintained at a uniform temperature in a short time of 5 minutes.

In the subsequent water absorption process, the entire inner pot 111 is once warmed in the same manner, and therefore, after reaching 60 ° C., it is not necessary to perform active stirring or heating, and a minimum amount of stirring that does not decrease the temperature is added.

However, when the sweetening increase rice cooking mode is selected and the holding time of the water absorption process is extended, the holding temperature of the water absorption process is set lower by several degrees C. than the standard rice cooking mode, and control is performed.

In the standard rice cooking mode, the water absorption process is 20 minutes, while in the sweetness increasing rice cooking mode, the water absorption process is extended to 30 minutes, and the holding temperature at that time is lower than that in the standard rice cooking mode. For example, in this embodiment, the holding temperature of the water absorption process in the standard rice cooking mode is 59 ° C., the holding temperature of the water absorption process in the sweetness increasing rice cooking mode is 58 ° C., and the holding time is extended by 10 minutes.

As described above, the rice cooker according to the present invention can increase the sweetness without changing the texture by lowering the holding temperature and extending the holding time during the water absorption process.

According to the rice cooker having the above configuration, when the sweetness increasing rice cooking mode is selected by the rice cooking mode selection unit 115d, the rice cooking control unit 115a performs a holding temperature lower than the holding temperature of the water absorption process in the standard rice cooking mode, and the standard By performing the water absorption process in the sweetness-enhancing rice cooking mode with a retention time longer than the retention time of the water absorption process in the rice cooking mode, the generation of reducing sugar can be promoted while suppressing the amount of spilled solids, making delicious rice well You can cook.

Further, by stirring the mixture of rice and water in the inner pot 111 immediately before (or immediately after) the water absorption step, the dissolved solids (mainly starchy substance) of the entire rice and water mixture in the inner pot 111 is obtained. ) Can be evenly distributed, so that a stirring mechanism can be used during cooking to cook rice with a good finish that is sweet but hardly burnt.

In the above embodiment, the stirring mechanism is configured by the motor 117 for driving the stirring blades, the timing belt 121, the twin blade mechanism 120, the inner lid 118, and the stirring blades 119, 119. You may apply this invention to the rice cooker provided with the stirring mechanism etc. which used the stirring blade etc. which were provided in the inner bottom face.

In the above embodiment, the stirring blades 119, 119, which are stirring mechanisms, are normally rotated in one direction. However, the stirring blades may be rotated in both forward and reverse directions during stirring.

Moreover, in the said embodiment, although the standard rice cooking mode and the sweet increase rice cooking mode were selected by the rice cooking mode selection part 115d, the sweet increase rice cooking mode is not restricted to this, For example, the some sweet increase rice cooking from which the quantity of a sweet component differs The mode may be selectable.

For example, in the above rice cooker, a plurality of sweetening rice cooking modes with different levels of sweetening increase can be selected by the rice cooking mode selection means, and the higher the sweetening degree, the holding temperature in the water absorption process by the rice cooking control means May be lowered and the holding time may be lengthened. By doing so, it is possible to cook rice with a good taste (texture) because it does not allow extra starch to flow out while drawing out more sweetness.

[Third Embodiment]
FIG. 11: is a schematic block diagram of the rice cooker of 3rd Embodiment of this invention.

As shown in FIG. 11, this rice cooker is connected to the main body 201 so that it can be opened and closed by a main body 201 having an opening, a rice cooker 202 accommodated in the main body 201, a pivot (hinge shaft) and a latch mechanism (not shown). And a lid 203. The lid 203 is provided with an inner lid 204, and a lid heater 205 and a lid temperature sensor 206 are further provided inside the inner lid 204. The inner lid 204 is provided with a rotating shaft 207 that passes through the inner lid 204 and the lid heater 205 in a non-contact manner, and a rotating body 208 that can rotate in synchronization with the rotating shaft 207. The rotating body 208 is provided with stirring blades 209 and 209 that stand (develop) and fall over the rotating body 208. The rotating shaft 207 is connected to a motor (not shown in FIG. 11) inside the lid 203 so that the rotating body 208 and, in turn, the stirring blades 209 and 209 can be driven to rotate.

The agitating blades 209 and 209 are transmitted with a rotational force from the rotating shaft 207 via a gear mechanism including a bevel gear (not shown), and are raised (deployed) and laid down according to normal rotation and reverse rotation of the rotating shaft 207. (Storing). The agitating blades 209 and 209 stand up from the rotating body 208, that is, rotate in conjunction with the rotating body 208 in a deployed state, so that the water and rice contained in the rice cooker 202 are stirred by the agitating blades 209 and 209. It has come to be.

The details of the gear mechanism are not the gist of the present invention and are well known in Japanese Patent Application Laid-Open No. 2012-135605 and the like, and thus detailed description thereof is omitted.

The rotating body 208, the gear mechanism, and the stirring blades 209 and 209 constitute an example of the stirring mechanism 220. However, any stirring mechanism may be used as long as it can stir the rice and water in the rice cooker 202. For example, Japanese Patent Application Laid-Open No. 62-144606, Japanese Patent No. 3121270, The stirring mechanism described in 2011-183085 may be used.

The casing of the lid 203 has a steam port 213 for letting water vapor generated in the rice cooker 202 to the outside during rice cooking, an information display indicating the operation state of the rice cooker, and an operation unit 214 for receiving a user command. The inner lid 204 is provided with a packing 215 that comes into close contact with the rice cooker 202 stored in the main body 201 when the lid 203 is closed.

Inside the main body 201, an outer pot 210 that constitutes a housing portion of the rice cooker 202, a heated object accommodated in the rice cooker 202, that is, a heater as an example of a heating portion for heating and keeping warm the cooked food 211, a temperature sensor 212 for detecting the temperature of the rice cooker 202 is disposed. A control device 230 (see FIG. 12) that controls the operation of the rice cooker is disposed on the lid 203 or the main body 201.

As shown in FIG. 11, the temperature sensor 212 is installed so that the bottom temperature of the rice cooker 202 can be measured, and the temperature sensor 212 measures the temperature of an object to be heated (rice, water) accommodated in the rice cooker 202. It has become so. In this embodiment, it has been confirmed that the wall surface temperature of the bottom of the rice cooker 202 is approximately equal to the temperature of the heated object accommodated in the rice cooker 202.

The operation unit 214 is integrally provided on the housing surface of the lid 203. It should be noted that the attachment position of the operation unit 214 is not limited to the present embodiment as long as the display information can be visually recognized by the user and the operation such as button operation can be performed.

The rice cooker is connected to a commercial power source via a power cord (not shown). The power supplied from the commercial power source is supplied to each unit via a power source unit (not shown).

The heater 211 as a heat source for heating and heat retention may be constituted by an IH (Induction Heating) heater in addition to a resistor heater such as a nichrome wire heater, and is particularly limited to these. is not.

In addition, the determination means of the weight of the rice accommodated in the rice cooker 202 may be measured by, for example, a separately installed weight sensor, or a load of a motor 221 (see FIG. 12) that rotates the rotating body 208. The weight of rice may be detected based on the detection result of a sensor that detects the water level in the rice cooker 202, or the user inputs the amount of rice from the operation unit 214. However, it is not particularly limited to these.

The rice cooking course is selected and determined by operating the buttons on the operation unit 214. The control device 230 controls the heater 211 based on the signal from the temperature sensor 212 according to the control program corresponding to the selected rice cooking course, controls the overturning and standing of the stirring blades 209, 209, and the rotating body. This is done by controlling the rotation speed and driving time.

FIG. 12 is a block diagram of the control device 230.

The control device 230 includes, for example, a microcomputer, and includes a heating control unit 231 that controls the heater 211, an intermittent drive period determination unit 232 that determines an intermittent drive period of the motor 221, a memory 233, and a motor 221. And a speed control unit 240 that performs speed control. The heating control unit 231, the intermittent drive period determination unit 232, and the speed control unit 240 are configured by software.

The heating control unit 231 controls the heater 211 so that the detected temperature of the temperature sensor 212 becomes the target temperature in accordance with the rice cooking course control program determined by the button operation of the operation unit 214, and the detected temperature is The temperature is controlled so as to reach the temperature shown in FIGS. 13A and 13B with time.

The intermittent drive period determination unit 232 counts the output of the timer in accordance with a predetermined program for an intermittent drive period for driving the stirring mechanism 220, that is, an intermittent drive period for driving the motor 221. As shown in FIG. That is, the intermittent driving period of 5 seconds is determined so that the motor 221 is driven for 5 seconds, paused for 10 seconds, driven for 5 seconds, and paused for 10 seconds.

The speed control unit 240 includes an initial duty ratio gradual increase means 241 as an example of an initial electrical characteristic value gradual increase means, a drive period duty ratio setting means 242 as an example of a drive period electrical characteristic value setting means, and a feedback control means. 243. The initial duty ratio gradual increase means 241, drive period duty ratio setting means 242 and feedback control means 243 are configured by software.

As shown in FIG. 14B, the first duty ratio gradual increase means 241 operates until the speed of the motor 221 and, consequently, the rotating body 208 and the stirring blades 209 and 209 reaches a predetermined target rotational speed during the initial drive period. Then, the duty ratio as an example of the electrical characteristic value is gradually increased from zero. Then, when the rotational speed of the motor 221 reaches the target rotational speed, the initial duty ratio gradual increase means 241 stops increasing the duty ratio and maintains the duty ratio. The rotational speeds of the motor 221, and hence the rotating body 208 and the stirring blades 209 and 209 are detected by the rotational speed sensor 225, and whether or not the rotational speed detected by the rotational speed sensor 225 has reached the target rotational speed. The first duty ratio moderate increase means 241 determines. The initial duty ratio gradual increase means 241 outputs a signal indicating a gradually increasing duty ratio as shown in FIG. 14B to the PWM circuit 222 to drive the motor 221 to perform the first time as shown in FIG. 14A. In the starting of the driving, the rotational speed (rpm) of the rotating body 208 is gradually increased.

Here, “slow” means an increasing gradient that does not cause an overshoot when the target rotational speed is reached or when the increase in rotational speed is stopped.

The drive period duty ratio setting means 242 stores the last stage duty ratio (see DT in FIG. 14B) in a certain drive period in the memory 233, and in the next drive period, the duty ratio stored in the memory 233 is stored. The ratio DT is set as a duty ratio for driving the motor 221. In other words, the duty ratio DT in a state where the motor 221 immediately before the end of the previous drive period is actually at the target rotational speed or a state assumed to be at the target rotational speed is stored in the memory 233. In the next driving period, driving of the motor 221 is started with the stored duty ratio DT. By doing so, the optimum duty ratio considering the history is set according to the amount of rice and water in the rice cooker 202, that is, according to the load of the motor 221, and the next driving period is set. Driving is started. Therefore, the overshoot of the rotational speed of the motor 221 is reduced.

The feedback control means 243 obtains a deviation between a predetermined target rotational speed of the motor 221 and a detected rotational speed from the rotational speed sensor 225, and performs, for example, a PID (Proportional Differential Integration) operation on the deviation to obtain a motor. The duty ratio as an operation amount for the rotational speed of 221 to be the target rotational speed is obtained and output to the PWM circuit 222.

The rice cooker with the above configuration operates as follows.

FIG. 13A and FIG. 13B are diagrams for explaining each step of rice cooking in the present embodiment.

In FIG. 13A, the vertical axis represents the water temperature, and the horizontal axis represents the elapsed time from the start of cooking. FIG. 13B shows the state of the stirring blades 209 and 209 and the operating state of the rotating body 208 in each step. Rice and water in the rice cooker 202 are controlled to the temperatures shown in FIGS. 13A and 13B by the heating control unit 231 of the control device 230 based on the output of the temperature sensor 212. 13A and 13B show a case where rice is cooked in a rice cooker of 5.5 go (1 go for rice is 150 grams) in which rice cooker 202 contains 3 go white rice.

In this embodiment, the stirring blades 209 and 209 are expanded (standing) from the rotating body 208 and rotated when the rice cooking is started, and the water and rice stored in the rice cooker 202 are stirred by the stirring blades 209 and 209 by the heater 211. When the water absorption heating process for heating is performed and the temperature sensor 212 reaches a temperature set within a temperature range of 54 to 66 ° C., the temperature of the temperature sensor 212 is similarly stirred while stirring the water and rice stored in the rice cooker 202. A water absorption process is performed to control heating by the heater 211 so that is maintained at the set temperature. Thereafter, the agitating blades 209 and 209 are accommodated (slipped) in the rotating body 208 and subjected to a boiling heating process in which the temperature sensor 212 is heated to 95 ° C. until the temperature sensor 212 reaches 95 ° C. A boiling process in which heating by the heater 211 is continued while rotating 208 is performed. Finally, a steaming process is performed to complete the cooking.

In the water absorption heating step and the water absorption step, the rice and water in the rice cooker 202 are stirred with the stirring blades 209 and 209 while being heated with the heater 211 to gelatinize the starch of the rice. Sufficient water can be sucked into the core. By adding water and heat to rice, the shape of raw starch changes and it becomes alpha (α) starch that is easy to digest. This change from raw starch to pregelatinized starch is called gelatinization. In addition to water and heat, starch is hydrolyzed by saccharifying enzymes to produce glucose as a sweet component.

The optimum temperature of the saccharifying enzyme is about 60 ° C., but the gelatinization temperature is about 60 to 64 ° C. for glutinous rice and about 55 to 60 ° C. for glutinous rice.

When gelatinization starts, when water and heat are added to the starch of rice, a phenomenon that changes into a paste is observed, and the surface of the rice grain gradually changes to a soft starch with stickiness. Therefore, when rubbing is continued, a large amount of solid content such as glue is eluted, and if the amount of the eluted solid content is excessively large, charring occurs. In addition, yellowing after incubation is caused by the Maillard reaction between glucose and amino acids.

Therefore, the temperature of the water absorption step is preferably 64 ° C. or lower in order to avoid elution of excessive solids and production of glucose.

First, the rotational speed (rpm) of the rotating body 208, that is, the stirring blades 209 and 209 in the water absorption heating process is shown in FIG. 14A, and the duty ratio of the input voltage from the PWM circuit 222 to the stirring motor 221 is shown in FIG. 14B. As shown in FIG. 14A, after the start of rice cooking, the speed control unit 240 so that the rotation speed of the stirring blades 209 and 209 in the first driving period (5 seconds) gradually increases from 0 rpm, that is, gradually increases from zero speed. 14D, the duty ratio of the input voltage to the motor 221 is gradually increased from 0%. Then, referring to the output of the rotational speed sensor 225, when a predetermined target rotational speed (150 rpm) is reached, the duty ratio DT at that time is maintained and the rotational speed is maintained.

In this way, the duty ratio is gradually increased from zero until the rotational speed of the agitating motor 221 reaches the target rotational speed (150 rpm), so overshooting occurs in the start-up operation in the first drive period (5 seconds). It can be prevented from cracking and damaging the rice.

Here, “slow” means an increasing gradient so that, when the target rotational speed (150 rpm) is reached, when the increase in rotational speed is stopped, substantially no overshoot occurs. In this embodiment, as an example, as shown in FIG. 14B, the increasing gradient is a duty ratio of 60% / 4 seconds.

On the other hand, the drive period duty ratio setting means 242 stores the final stage duty ratio (DT in FIG. 14B) in the first drive period (0 to 5 seconds) shown in FIG. 14A in the memory 233 and the first time. In the next driving period (15 to 20 seconds) following this driving period, the duty ratio DT stored in the memory 233 is read, and the driving of the motor 2 is started at the duty ratio DT.

As described above, the driving period duty ratio setting means 242 causes the motor 221 immediately before the end of the previous driving period to be in the target rotational speed, or to be assumed to be in the target rotational speed. The duty ratio DT is stored in the memory 233, and in the next driving period, the motor 221 starts to be driven with the stored duty ratio DT. Therefore, according to the amount of rice and water in the rice cooker 202, that is, The optimum duty ratio DT is set in consideration of the history in accordance with the load of the motor 221 and the driving of the motor 221 is started at this duty ratio DT. Therefore, the overshoot of the rotational speed of the motor 221 is eliminated or reduced.

Further, the feedback control means 243 starts the driving of the motor 221 with the duty ratio DT, and then the target rotation speed (150 rpm) of the stirring blades 209 and 209 and the stirring blade 209, The deviation from the detected rotational speed of 209 is obtained, and, for example, PID (proportional differential integration) calculation is performed on this deviation, and the duty ratio as an operation amount for the rotational speed of the stirring blades 209 and 209 to become the target rotational speed is obtained. Then, the motor 221 is driven with the obtained duty ratio.

As described above, in the second drive period, after the motor 221 starts to be driven at the duty ratio DT set by the drive period duty ratio setting unit 242, the agitation blades 209 and 209 are moved to the target rotational speed by the feedback control unit 243. Therefore, the stirring blades 209 and 209 can be more accurately rotated at the target rotational speed with less overshoot, while reducing the influence of disturbance.

Therefore, it is possible to reduce the overshoot of the rotation speed of the motor 221, and consequently the stirring blades 209, 209, to prevent rice cracking and surface damage, and to prevent deterioration of the appearance.

Further, since the feedback control means 243 feedback-controls the rotational speed of the motor 221, the duty ratio of the preceding driving period is a more accurate value because the stirring blades 209 and 209 have the target rotational speed. Thus, the drive period duty ratio setting means 242 stores a more appropriate duty ratio in the preceding drive period in the memory 233, and starts driving the motor 221 at this more appropriate duty ratio in the next drive period. be able to.

Therefore, it is possible to reduce the overshoot of the rotational speed of the stirring blades 209 and 209, and to prevent rice cracking and surface damage.

For the third drive period, the drive is started with the duty ratio of the final stage during the second drive period, and for the fourth drive period, the drive is started with the duty ratio of the final stage during the third drive period. To do. The same applies hereinafter.

Further, in the rice stirring operation by the stirring mechanism 220 after the water absorption step, when the set rotation speed is the same as that in the water absorption heating step, the same control as the second and subsequent operations in the water absorption heating step is performed. On the other hand, when the set number of rotations is different, the same control as the first time of the water absorption heating process is performed, and similarly, the control for reflecting the second and subsequent operations is performed.

Although not shown, in this embodiment, as shown in FIG. 14A, the ON / OFF time of the motor 221 in the water absorption heating process is 5/10 seconds, the ON / OFF time of the water absorption process is 2/120 seconds, The PWM frequency of the motor 221 in the water absorption heating process and the water absorption process was 20 kHz, and both were performed at the same set rotational speed of 150 rpm. Each value varies depending on the shape of the stirring blade, rice cooker, etc., and the specifications of the stirring motor, and is not limited.

15A and 15B are graphs for explaining the operation of the comparative example, in which only the feedback control of the motor is performed so that the stirring blade has the target rotational speed.

According to the feedback control of this comparative example, since the control is based on the deviation between the target rotational speed and the actual rotational speed, the agitating blade causes a considerably large hunting as shown in FIG. Will also vary as shown in FIG. 15B.

For this reason, if the motor 221 (stirring blades 209, 209) significantly exceeds the target rotational speed (set rotational speed) due to overshoot, an excessive load is applied to the rice and the rice is cracked or the surface of the rice is The problem of being hurt occurs.

On the other hand, according to the present embodiment, the stirring blades 209 and 209 hardly exceed the set rotation speed, so that the optimum temperature of the saccharifying enzyme is about 60 ° C. while properly stirring the rice. It is possible to heat to the front and back quickly while suppressing the temperature unevenness of the rice.

In the above embodiment, the initial duty slowly increasing means 41, the drive period duty ratio setting means 242 and the feedback control means 243 are used together. However, when the disturbance is small, the feedback control means 243 is removed, The rotational speed of the motor 221 can be accurately controlled even by using only the initial duty slowly increasing means 41 and the driving period duty ratio setting means 242. Further, the rotational speed of the motor 221 can be controlled fairly accurately even if the initial duty gradually increasing means 41 is removed and the feedback control means 243 and the drive period duty ratio setting means 242 are used.

However, when the initial duty slowly increasing means 41, the drive period duty ratio setting means 242 and the feedback control means 243 are used in combination, the duty ratio is set so that there is no overshoot, and the set speed is strong against disturbance and stably. can do.

[Fourth Embodiment]
FIG. 16: is a block diagram which shows the principal part of the rice cooker of 4th Embodiment of this invention.

In the fourth embodiment of FIG. 16, the components other than the speed control unit 245 are the same as the components of the third embodiment of FIG. 12, so FIG. 12 is used for them, and the description thereof is omitted. To do.

16 differs from the speed controller 240 shown in FIG. 12 only in that it has a duty ratio gradually increasing means 246 and a rotational speed gradually decreasing means 247 as an example of the electrical characteristic value gradually increasing means. Therefore, the initial duty ratio gradual increase means 241, the drive period duty ratio setting means 242 and the feedback control means 243 are denoted by the same reference numerals as those in the third embodiment of FIG.

The duty ratio gradual increasing means 246 is configured by software, and at the beginning of the next driving period, for example, at the beginning of the second driving period shown in FIG. 17, the duty set by the driving period duty ratio setting means 242 is set. Until the ratio is reached, the duty ratio is gradually increased, that is, gradually increased, as indicated by the straight line GU. The duty ratio gradual increase means 246 may read data representing the straight line GU previously stored in the memory 233 to obtain the duty ratio, or may obtain the duty ratio by an expression representing the straight line GU.

In this way, the duty ratio gradually increasing means 246 makes the overshoot smaller as shown by the straight line GU in FIG. 17 when the duty ratio rises, and also reduces the overshoot between the stirring blades 209 and 209 and the rice. The relative speed is reduced, and cracking and damage of rice can be reduced.

Further, the rotational speed gradually decreasing means 247 gradually decreases the rotational speed at the end of the driving period of 5 seconds as shown by the straight line GD in FIG. 17, so that the relative speed between the stirring blades 209 and 209 and the rice is further increased. It can be reduced to reduce cracking and damage of rice.

The rotational speed gradual reduction means 247 may be configured by software and read the data representing the straight line GD previously stored in the memory 233 to obtain the duty ratio, or obtain the duty ratio by an expression representing the straight line GD. You may do it. Further, the rotational speed gradual decrease means stops supplying power to the motor 221 slightly before the end of the drive period, and rotates the rotating body 208 and the stirring blades 209 and 209 with inertia, gradually. You may make it stop at a reduced speed.

In the fourth embodiment, the duty ratio is described as an example of the electrical characteristic value. However, the electrical characteristic value may be a voltage value or a current value.

In the fourth embodiment, the stirring mechanism 220 is intermittently agitated in the water absorption heating process and the water absorption process. However, in any one of the water absorption heating process and the water absorption process, the stirring mechanism 220 is intermittently operated. A stirring operation may be performed.

Moreover, although the rice cooker as an example of the heating cooker has been described in the above embodiment, the heating cooker may be a range or an oven. Any cooking device may be used as long as it can cook rice.

Although specific embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

Moreover, the rice cooker of this invention is
An inner pot containing a mixture of rice and water;
A rice cooker body for storing the inner pot;
A heating unit for heating the inner pot;
A temperature detector for detecting the temperature of the inner pan;
A rice cooking control means for performing a rice cooking process including at least a water absorption process and a heating process by controlling the heating unit based on the detection temperature of the temperature detection unit,
A stirring mechanism for stirring the mixture of rice and water in the inner pot;
Agitation control means for controlling the agitation mechanism so as to agitate the mixture of rice and water in the inner pot immediately before or after the end of the water absorption step;
A rice cooking mode selection means for selecting at least one of the standard rice cooking mode and the sweetness increasing rice cooking mode,
When the sweetening increase rice cooking mode is selected by the rice cooking mode selection means, the rice cooking control means has a holding temperature lower than the holding temperature of the water absorption process in the standard rice cooking mode, and the standard rice cooking mode. The water absorption step according to the sweetness increasing rice cooking mode is performed with a holding time longer than the holding time of the water absorption step.

According to the said structure, when sweetness increase rice cooking mode is selected by the rice cooking mode selection means, the holding temperature lower than the holding temperature of the water absorption process at the time of the standard rice cooking mode, and at the time of the standard rice cooking mode by the rice cooking control means. The water absorption process by the sweetness increasing rice cooking mode is performed with a retention time longer than the retention time of the water absorption process. For example, by setting the holding temperature of the water absorption process as low as 55 ° C., it becomes possible to suppress the amount of the spilled solids, but since the amount of reducing sugar produced is reduced due to the decrease in the holding temperature, the water absorption process is maintained. By increasing the time, the total amount of reducing sugar produced can be increased. Therefore, the production of reducing sugar can be promoted while suppressing the amount of spilled solids, and delicious rice can be cooked well.

This rice cooker controls the agitation mechanism so as to agitate the mixture of rice and water in the inner pot immediately before or after the end of the water absorption process. Here, “immediately before the end of the water absorption process” means a period near the end of the water absorption process and within the period before the end time, and “immediately after the end of the water absorption process” means near the end time of the water absorption process and from the end time. It is in a later period.

In addition, by stirring the mixture of rice and water in the inner pot immediately before (or immediately after) the water absorption process, the spilled solid content (mainly starch) of the entire rice and water mixture in the inner pot is made uniform. Can be distributed. Therefore, by using the stirring mechanism during cooking of rice, it is possible to cook rice with good finish that is sweet but hardly burnt.

Moreover, the heating cooker of this invention is
A rice cooker for storing a heated object including rice and water;
A stirring mechanism for stirring the object to be heated in the rice cooker;
A motor for driving the stirring mechanism to stir the object to be heated;
A heating unit for heating the rice cooker;
A temperature sensor for detecting the temperature of the object to be heated;
Based on the output of the temperature sensor, a heating control unit that controls the heating unit so that the temperature of the object to be heated becomes a predetermined temperature;
In a water absorption heating process for heating the object to be heated from room temperature to a predetermined temperature and a water absorption process for maintaining the object to be heated at the predetermined temperature, a speed control unit for controlling the speed of the motor in an intermittent driving period; Prepared,
The speed controller is
The electric characteristic value for driving the motor at the final stage in a certain driving period is stored in the memory, and the electric characteristic value is set so that the motor is driven with the electric characteristic value stored in the memory in the next driving period. And a drive period electrical characteristic value setting means.

According to the heating cooker having the above configuration, in the water absorption heating process for heating and heating rice and water from room temperature to a predetermined temperature and the water absorption process for maintaining the heated object at the predetermined temperature by the speed control unit, the motor Are driven during intermittent driving periods, so that the temperature unevenness of the rice in the rice cooker can be prevented by stirring, and the rice cooking time can be shortened. In particular, since the drive period of the motor, and hence the stirring mechanism, is intermittent, excessive gelatinization of the rice can be prevented. If the stirring mechanism is continuously driven in the water absorption heating process or the water absorption process, there is a risk of excessive gelatinization of the rice.

On the other hand, the drive period electrical characteristic value setting means stores the electrical characteristic value for driving the motor in a final stage in a certain drive period in the memory and the electrical characteristic value stored in the memory in the next drive period. To drive the motor. Here, the electrical characteristic value is a duty ratio of PWM control, a voltage value of voltage control, a current value of current control, or the like.

As described above, the electric characteristic value for driving the motor in the final stage in a certain driving period is stored in the memory, and the stored electric characteristic value is set as the electric characteristic value for driving the motor in the next driving period. Regardless of the amount of rice and water in the rice cooker, that is, regardless of the load of the motor, the optimum electrical characteristic value can be set in consideration of the history, and therefore the motor rotation speed overshoot Can be reduced to prevent cracking of the rice and scratching of the surface.

In one embodiment,
A rotational speed sensor for detecting the rotational speed of the motor;
Feedback control means for controlling the electrical characteristic value so that the rotational speed of the motor becomes a predetermined target rotational speed based on the output of the rotational speed sensor.

According to the above embodiment, the feedback control means and the drive period electrical characteristic value setting means are used in combination, while controlling the rotation speed of the motor to be a predetermined target rotation speed during a certain drive period, The electric characteristic value for driving the motor at the final stage in a certain driving period is stored in the memory, and the electric characteristic value for driving the motor in the final stage in a certain driving period is received in the next driving period (influence of the feedback control). Is read out from the memory and set as the electrical characteristic value for the next driving period, so that the amount and state of rice and water in the rice cooker during the next driving period, that is, The motor can be driven with an optimal electrical characteristic value corresponding to the motor load.

Therefore, it is possible to reduce the overshoot of the rotation speed of the motor and prevent cracking of the rice and scratching of the surface.

In one embodiment,
Electrical characteristic value gradual increase means is provided for gradually increasing the electric characteristic value until the electric characteristic value set by the driving period electric characteristic value setting means is reached at the beginning of the next driving period.

According to the embodiment, the electrical characteristic value is gradually increased by the electrical characteristic value gradually increasing unit until the electrical characteristic value set by the driving period electrical characteristic value setting unit is reached at the beginning of the next driving period. Since it increases, the overshoot becomes smaller and cracking and damage of rice can be reduced.

In one embodiment,
In the first drive period, there is provided an initial electrical characteristic value slow increasing means for gradually increasing the electrical characteristic value from zero until the rotational speed of the motor reaches the target rotational speed.

According to the above-described embodiment, the electrical characteristic value is gradually increased from zero until the rotational speed of the motor reaches the target rotational speed in the initial drive period by the first electrical characteristic value gradual increase means. In this way, since the electrical characteristic value is gradually increased from zero until the motor rotation speed reaches the target rotation speed, overshoot does not occur in the start-up operation in the first driving period, and cracking and damage of the rice occur. Can be prevented.

In addition, the above-mentioned “slow” means a small increase gradient that does not cause overshoot when the increase in the rotation speed is stopped when the target rotation speed is reached.

When the electric characteristic value for the first driving period is determined by the first electric characteristic value gradual increase means, it is possible to set the electric characteristic value in the next driving period.

More specifically, in the first time, that is, in the first drive period, the rotation speed / min of the stirring mechanism determined according to the rotation speed of the motor is started from 0 rpm, and the rotation speed is increased until the target rotation speed is reached. The electric characteristic value of the motor when it gradually increases and reaches the target rotational speed is stored in the memory. In the subsequent drive period, that is, as the operation in the second and subsequent drive periods, the motor can be driven with the electrical characteristic value stored in the first operation immediately after the start.

Therefore, it is possible not to use the feedback control means.

However, the electrical characteristic value can be set more optimally when the first electrical characteristic value slow increasing means and the feedback control means are used in combination.

In one embodiment,
At the end of the driving period, there is provided a rotational speed gradual decrease means for gradually decreasing the rotational speed of the motor.

According to the embodiment, since the rotational speed of the motor is gradually reduced at the end of the driving period, the relative speed between the rice and the stirring mechanism is reduced, and cracking and damage of the rice can be reduced. .

The method of controlling the motor rotational speed to gradually decrease, that is, to gradually decrease, may be to decrease the electrical characteristic value gradually, or to turn off the power supply to the motor before the end of the driving period. Then, the stirring mechanism and the motor may be moved by inertia to stop naturally.

DESCRIPTION OF SYMBOLS 10 ... Rice cooker main body 11 ... Inner pan 12 ... IH heater 13 ... Power supply device 14 ... Temperature sensor 15 ... Control device 15a ... Rice cooker control part 15b ... Agitation control part 15c ... Timer 16 ... Lid body 17 ... Motor 18 ... Inner lid 19 , 19 ... Stirrer blade 20 ... Twin blade mechanism 21 ... Timing belt 22 ... Steam cylinder 23 ... Rice and water mixture 30 ... Rotating mechanism 110 ... Rice cooker body 111 ... Inner pan 112 ... IH heater 113 ... Power supply device 114 ... Temperature sensor DESCRIPTION OF SYMBOLS 115 ... Control apparatus 115a ... Rice cooking control part 115b ... Agitation control part 115c ... Timer 115d ... Rice cooking mode selection part 116 ... Lid body 117 ... Motor 118 ... Inner lid 119, 119 ... Agitation blade 120 ... Twin blade mechanism 121 ... Timing belt 122 ... Steam cylinder 123 ... Mixture of rice and water 130 ... Rotating mechanism 201 ... Main body 202 ... Rice cooker 203 ... Lid 204 ... Inner lid 208 ... Rotating body 209, 209 ... Agitation blade 210 ... Inner pan 211 ... Heater 212 ... Temperature sensor 220 ... Agitation mechanism 221 ... Motor 222 ... PWM circuit 230 ... Controller 240, 245 ... Speed controller 233 ... Memory 241 ... First duty ratio slow increase means 242 ... Drive period duty ratio setting means 243 ... Feedback control means 245 ... Speed control section 246 ... Duty ratio gradually increase means 247 ... Rotational speed gradually decrease means

Claims (4)

1. An inner pot (11) that contains a mixture of rice and water;
   A rice cooker body (10) for storing the inner pot (11);
   A heating section (12) for heating the inner pot (11);
   A temperature detector (14) for detecting the temperature of the inner pan (11);
   A rice cooking control means (15a) for performing a rice cooking step including at least a water absorption step and a heating step by controlling the heating unit (12) based on the temperature detected by the temperature detection unit (14),
   A stirring mechanism (17, 18, 19, 19, 20, 21) for stirring the mixture of rice and water in the inner pot (11);
   Stirring that controls the stirring mechanism (17, 18, 19, 19, 20, 21) so as to stir the mixture of rice and water in the inner pot (11) immediately before or after the end of the water absorption step. A rice cooker comprising a control means (15b).
2. In the rice cooker according to claim 1,
   In the water absorption step, the heating pot (12) heats the inner pot (11) so that the mixture of the rice and water stored in the inner pot (11) has a preset temperature. One period and a second period for maintaining the preset temperature following the first period,
   The stirring control means (15b) controls the stirring mechanism (17, 18, 19, 19, 20, 21), and the rice in the inner pot (11) during the first period of the water absorption step. A rice cooker characterized by stirring a mixture of water.
3. In the rice cooker according to claim 2,
   The stirring control means (15b) controls the stirring mechanism (17, 18, 19, 19, 20, 21) to reduce the stirring amount less than the stirring amount in the first period of the water absorption step, and The mixture of rice and water in the inner pot (11) is stirred during the second period of the water-absorbing step with a smaller amount of agitation than immediately before or after the end of the water-absorbing step. rice cooker.
4. In the rice cooker according to claim 1,
   In the water absorption step, the heating pot (12) heats the inner pot (11) so that the mixture of the rice and water stored in the inner pot (11) has a preset temperature. One period and a second period for maintaining the preset temperature following the first period,
   The agitation control means (15b) controls the agitation mechanism (17, 18, 19, 19, 20, 21), so that the agitation control means (15b) separates the agitation immediately before or after the end of the absorptive process. A rice cooker characterized in that the mixture of rice and water in the inner pot (11) is stirred during two periods with a stirring amount smaller than the stirring amount immediately before or after the end of the water absorption step.

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