JP2011224167A - Electric rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric rice cooker, dipping rice in a pot in water having an ordinary temperature, and easily and accurately determining the amount of rice to cook well.SOLUTION: This electric rice cooker includes a pot for putting material to be cooked; a heating means for the material to be cooked; a temperature detecting means for the inside of the pot; and a control device for inputting the output from the temperature detecting means to perform a rice cooking process. The control device determines the amount of rice and performs the rice cooking process including a water absorbing step I for making the material to be cooked in the pot absorb water, a rise heating step II for heating the material to be cooked which has absorbed water with rising temperature until boiling, and a boiling keeping step III of keeping the inside of the pot in the boiling state after the rise heating step. In the rise heating step II and the boiling keeping step III, reference temperature rising curves IIN, IIIN corresponding to the reference amounts of rice cooked are previously set, and after the rice to be cooked in the pot is made to absorb ordinary temperature water in the water absorbing step, the heating control is performed to shift to the reference temperature rising curves IIN, IIIN from the latter half of the rise heating step based on the determination result on the amount of rice cooked in the former half of the subsequent rise heating step.

Description

  The present invention relates to an electric rice cooker, more specifically, by immersing rice in room temperature water for a predetermined time during rice cooking and making the rice cooking amount easy and accurate, and by controlling rice cooking based on this accurate amount determination result It relates to an electric rice cooker that can cook delicious rice.

  Electric rice cookers (hereinafter referred to as rice cookers) are already a necessity in general households, and various types have been commercialized. This type of rice cooker is roughly divided into a type that cooks the pressure in the pan at about normal pressure during cooking and a type that cooks by raising the pressure to a predetermined pressure. In recent years, these rice cookers have been equipped with a microcomputer, which can be used to adjust various rice cooking courses, for example, rice rice cooking courses according to rice varieties such as white rice and brown rice, hard and soft. Now, you can do your favorite rice cooking course where you can cook your favorite rice and sushi rice rice cooking course that cooks sushi rice. These rice cooking courses are a water absorption process in which a predetermined amount of water is absorbed by the rice in the pot, a standing heating process in which the pot is heated and boiled at once after water absorption, and the starch of the rice is gelatinized while maintaining this boiling state. It is performed by a series of processes including a boiling maintaining process for cooking and a steaming process for removing excess moisture from the cooked rice and further promoting gelatinization. Moreover, in this series of rice cooking processes, the amount of rice cooked in the pan is determined, and the amount of heating in the rising heating process and the boiling maintaining process is controlled based on the result of the determination. Usually, this amount determination is performed in the rising heating process, the water absorption process, or both of these processes.

  For example, the rice cooker described in the following patent document 1 is carrying out quantity determination by the start-up heating process. If the amount is determined in the start-up heating process, the amount can be determined even in a rice cooking course that omits the water absorption process, for example, a quick-cooking course, and in this start-up heating process, the temperature rise in the pan is steep. Since the temperature gradient becomes large, there is a merit that the quantity can be easily determined using this steep temperature gradient. However, since it is impossible to control the time in the start-up heating process in the amount determination in the start-up heating process, it becomes difficult to control the heating amount in the start-up heating process corresponding to the amount of rice cooking. Therefore, there is a demerit (problem) that it becomes difficult to cook rice that is hard or soft. In order to solve this problem, a rice cooker has been proposed in which the amount can be determined in the water absorption step before the start-up heating step.

  For example, the rice cooker described in Patent Document 2 below is based on the energization time to the IH heater necessary to maintain a predetermined water absorption temperature (59 to 60 ° C.) during the water absorption time. Judgment is being made. According to this rice cooker, the heating amount corresponding to the amount of rice cooking can be controlled immediately after the water absorption step is completed and immediately after the transition to the rising heating step. In particular, since the time during which the temperature rise characteristic is set to a predetermined value in the start-up heating process can be controlled, it is possible to cook rice of any taste, such as hard or soft. In addition, since there is a problem even in the amount determination in the water absorption step, a rice cooker in which the amount determination is performed in both the water absorption step and the start-up heating step is also proposed (for example, the following patent document) 3).

Japanese Utility Model Publication No. 2-51829 (page 3-4, FIG. 9) JP 2009-100787 (paragraphs [0034] to [0039], FIG. 6) JP-A-2005-65928 (paragraphs [0014] and [0015], FIG. 3)

  As in the rice cooker of Patent Document 1 described above, when the amount is determined in the start-up heating process, the temperature rise gradient becomes steep, so that the amount can be easily determined using this steep rise gradient. On the other hand, there are disadvantages such as making it harder and harder to cook rice. However, it has been found that this amount determination also has a new problem in relation to the water absorption process. The problem is that the water absorption temperature is usually set to a temperature higher than room temperature. For example, in the rice cooker of the above-mentioned Patent Document 2, the water absorption temperature is about 60 ° C. However, when water is absorbed at such a water absorption temperature, the temperature rise in the pan in the rising heating process after water absorption is as shown in FIG. Furthermore, it has been found that the temperature rise characteristics are almost the same regardless of the amount of cooked rice. That is, referring to FIG. 11, TS ′, TN ′, and TL ′ are temperature rise curves corresponding to the amount of rice cooked, and TS ′ is 0.5 cup, TN ′ is 3.0 cup, and TL ′ is 5 .5 cups are supported. In the start-up heating process, these temperature rise curves are almost overlapped, that is, almost the same regardless of the amount of cooked rice, and it is extremely difficult to distinguish them. Therefore, if the amount is determined using the temperature rise in the start-up heating process, the accuracy is lacking.

  The above disadvantages of the rice cooker of Patent Document 1 can be eliminated by adopting the amount determination technique disclosed in Patent Document 2. Moreover, since the quantity determination technique of the said patent document 3 performs quantity determination in both processes of a water absorption process and a start-up heating process, it will be further improved. However, some problems are inherent in the amount determination in the water absorption process of Patent Documents 2 and 3. One problem is that the temperature range of the water absorption temperature is narrow (for example, the temperature range of Patent Document 2 is 59 to 60 ° C.), and the gradient of temperature rise in this temperature range is extremely small, so accurate determination is possible. Is difficult. Another problem is that it is easily affected by the initial water temperature. For example, if the initial water temperature exceeds the set water absorption temperature, the determination cannot be made. In addition, since the set water absorption temperature is set to 59-60 degreeC, the rice cooker of the said patent document 2 does not have a possibility of being influenced by the initial water temperature, but if this set temperature is set to the normal temperature vicinity, it will become easy to be influenced. .

  Yet another issue is the inability to absorb enough water into the rice. The rice cooker of the said patent document 2 is heated up to about 60 degreeC at the water absorption process, and has shortened the water absorption time. However, when water is absorbed by raising the temperature in the pan to approximately 60 ° C., the time required for water absorption is shortened, but there is a risk that the water absorption rate varies between the outside and inside of the rice. In addition, when trying to allow sufficient water absorption to the inner core of the rice, the outer side of the rice is immersed in warm water for a long time while remaining wet until it is substantially saturated, and the surface may be cracked. . Therefore, when water enters the cracked part, a part of the rice, that is, the solid content, peels and elutes, and the surface structure of the rice collapses. The cooked rice becomes watery and has a poor taste.

  By the way, in conventional rice-cooking rice cooking, rice was cooked after soaking the rice in room temperature water for a long time before cooking and allowing the water content to reach a substantially saturated value. According to this cooking method, there is almost no difference in moisture content between the inside and outside of the rice, and water can be absorbed without breaking the structure of the surface of the rice. However, the water absorption with room temperature water is difficult to adjust the time because the temperature of the room temperature water changes depending on the season and the water absorption rate also changes depending on the type of rice and the amount of rice cooked. If you try to control this time with the current electric rice cooker, you will have to rely on the intuition of the user, and for this reason, you may be forced to immerse in room temperature water for a long time. Calculations are not possible, and cooking your favorite rice becomes difficult.

  The present inventors have a problem inherent to the amount determination in the start-up heating process, and the inherent problem can be solved by changing to the amount determination in the water absorption process, but there is also a problem in the determination in this water absorption process. Because of the inherent nature, we examined how to achieve adequate rice cooking control by sufficiently absorbing water in the cooked rice in the pan and determining the amount easily and accurately. As a result, it is possible to execute ideal water absorption by immersing in room temperature water of traditional cooking methods for a predetermined time, and after the water absorption process with this room temperature water is completed, the process proceeds to the rising heating process. As shown in the curves TS ′, TN ′, TL ′ of FIG. 11 to the curves TS, TN, TL of FIG. It was found that curves with different amounts of cooking rice hardly overlap and that the difference in the amount of cooking rice appears remarkably. In this way, by performing the quantity determination in the startup heating process after the water absorption process with room temperature water, the quantity determination can be performed easily and accurately, and if the quantity determination is performed at the initial stage of the startup heating process. Based on this accurate quantity determination result, it is conceived that the subsequent heating control, that is, the heating control in the rising heating process including the latter half of the rising heating process and / or the boiling maintaining process of the transition can be performed accurately. Thus, the present invention has been completed.

  The present invention solves the problems of the prior art, and has been made based on the above knowledge, and the object of the present invention is to sufficiently immerse the rice in the pan in room temperature water and easily determine the amount. It is to provide a rice cooker that can cook delicious rice by controlling the heating accurately based on this amount determination. More specifically, after the rice is immersed in room temperature water for a relatively long predetermined time to sufficiently absorb water, the amount of rice cooked is determined at an early stage of the start-up heating process, and based on this amount determination, It is intended to provide a rice cooker that can cook delicious rice by optimal water absorption and heating temperature control by performing the heating temperature control in accordance with the temperature rise of the optimum reference value.

  Another object of the present invention is that, in addition to the above-mentioned purpose, when the room temperature water is absorbed over a long time, the entire rice cooking time becomes longer, so that the water absorption time with this room temperature water is adjusted so that rice can be cooked. The purpose is to provide a rice cooker.

In order to achieve the above object, the invention according to claim 1 is characterized in that a pan for storing a predetermined amount of cooked rice, a heating means for heating the cooked rice in the pan, and a temperature for detecting the temperature in the pan. A detection means and a control device for executing a predetermined rice cooking process by inputting an output from the temperature detection means, wherein the control device absorbs a predetermined amount of water into the cooked rice in the pan, A series of rice cooking steps including a rising heating step of heating and heating the absorbed rice cooked until boiling, and a boiling maintaining step of maintaining the inside of the pan in a boiling state after the rising heating step, the amount of rice cooking in the pan In the electric rice cooker to be determined and executed, a reference temperature rise curve corresponding to a reference rice cooking amount is set in advance in the start-up heating step, and the controller is provided with the rice cooker in the pan in the water absorption step. After absorbing room temperature water over a predetermined time, Control means for determining the amount of rice cooked in the first half of the start-up heating step and performing heating control for shifting the temperature in the pan from the second half of the start-up heating step to the reference temperature rise curve based on this amount determination Is provided.

  In the electric rice cooker according to claim 1, in the electric rice cooker according to claim 1, a reference temperature increase curve corresponding to the reference rice cooking amount is set in advance in the boiling maintaining step in addition to the rising heating step, The said control apparatus shifts the temperature in the said pan to the said reference temperature rise curve after completion | finish of the said start-up heating process, It is characterized by the above-mentioned.

  According to a third aspect of the present invention, in the electric rice cooker according to the first aspect of the present invention, the control device includes a process from the time of shifting to the rising heating process after the completion of the water absorption process until reaching a predetermined reference temperature. An amount determining means for measuring the amount of rice by measuring time is provided.

  The invention according to claim 4 is the electric rice cooker according to claim 3, wherein the reference temperature is set to a temperature exceeding the temperature of the room temperature water.

  The invention according to claim 5 is the electric rice cooker according to claim 1 or 4, wherein the reference rice cooking amount is set to a substantially intermediate rice cooking amount of the maximum rice cooking amount and the minimum rice cooking amount, and the control device is In the start-up heating step, when the amount of cooked rice is smaller than the intermediate amount of cooked rice, the amount of heating is reduced, and when the amount is large, the amount of heating is increased to shift the temperature in the pan to the temperature rise curve. And

  The invention according to claim 6 is the electric rice cooker according to claim 1, wherein in the water absorption step, the water absorption time of the cooked rice corresponding to the temperature of room temperature water is set in advance, and the control device The temperature in the pan at the start of water absorption is detected by a detecting means, the water absorption time is determined, and the water absorption step is executed.

  The invention according to claim 7 is the electric rice cooker according to claim 6, wherein the water absorption time is set short when the temperature of the room temperature water is high, and long when the temperature of the room temperature water is low.

  By providing the above configuration, the present invention has the following excellent effects. That is, according to invention of Claim 1, 2, since normal temperature water is made to absorb water in a rice cooked thing over a predetermined time in a water absorption process, sufficient normal temperature water can be made to absorb water in a rice cooked food. Moreover, in the next start-up heating process, when the temperature rise in the pan in this start-up heating process is measured, when the temperature rise is absorbed by hot water of around 60 ° C., for example, according to the amount of rice cooked Compared with, the temperature can be distinguished significantly, and the rice cooking amount can be easily and accurately determined using this temperature rise. Then, this amount determination is determined in the first half of the start-up heating process, that is, at an early stage of the water absorption process, and based on this amount determination, heating control is performed to shift from the latter half of the start-up heating process to the reference temperature rise curve. Therefore, ideal heating control can be performed in the start-up heating process, and optimal rice cooking is possible.

  Moreover, since it shifts to a reference | standard temperature rise curve after a start-up heating process, ideal heating control can be performed after a start-up heating process, and optimal rice cooking becomes possible.

  Moreover, according to invention of Claim 3, 4, by measuring the time until it reaches | attains to predetermined | prescribed reference temperature from the time which transfers to the standing-up heating process after completion | finish of a water absorption process by quantity determination means, Judgment can be made easily.

  According to the invention of claim 5, since the reference rice cooking amount is set to a substantially intermediate rice cooking amount between the maximum rice cooking amount and the minimum rice cooking amount, and the rice cooking control is performed based on the temperature rise curve corresponding to the substantially intermediate rice cooking amount, It becomes easy to cope with large and small rice cooking amounts, and optimal rice cooking according to the amount of rice cooking becomes possible.

  According to the invention of claim 6, although the water absorption speed absorbed by the rice to be cooked varies depending on the water temperature at the time of rice cooking, in this invention, the water absorption time corresponding to the water temperature is set in advance and corresponds to the water temperature for each rice cooked. Since the water absorption time is selected and the rice to be cooked is immersed in the water absorption time corresponding to this water temperature, sufficient water is absorbed into the rice to be cooked in the optimum time. As a result, the heat conduction of the to-be-cooked rice becomes good, and delicious rice with no core can be cooked.

  According to the invention of claim 7, the cooked rice can be hydrated with the normal temperature water until the water content becomes substantially saturated regardless of the temperature of the normal temperature water used during cooking.

It is a front view of the rice cooker which concerns on embodiment of this invention. It is a longitudinal cross-sectional view of the rice cooker of FIG. It is the expanded sectional view which expanded the pressure valve opening mechanism of FIG. It is a block diagram which comprises a control apparatus. It is the temperature rise curve which showed the change of the temperature in the pan in a rice cooking process. It is the temperature rise curve which expanded a part of FIG. FIG. 7 shows the time of the start-up heating process and the boiling maintenance process for each amount of cooked rice, and FIG. 7A is a time chart showing the time taken for the start-up heating process and the boiling maintenance process in FIG. b) is a time table showing the time required for the start-up heating process and the boiling maintenance process of the prior art (FIG. 11). FIG. 8A is a table showing the relationship between the immersion time and the solid content elution amount, and FIG. 8B is a table showing the water absorption time to be set according to the difference in water temperature. It is a flowchart figure of the rice cooking process of this invention. It is a flowchart figure of the rice cooking process following FIG. It is a temperature rise curve in the rice cooking process of the rice cooker of a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment shown below exemplifies a rice cooker for embodying the technical idea of the present invention, and is not intended to specify the present invention for this rice cooker. It is equally applicable to those of other embodiments within the scope. That is, although the rice cooker demonstrated below is a pressure type rice cooker, it is not limited to this, It can apply also to a non-pressure type rice cooker.

  With reference to FIGS. 1-4, the structure and control apparatus of the rice cooker which concern on embodiment of this invention are demonstrated. 1 is a front view of a rice cooker according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the rice cooker of FIG. 1, and FIG. 3 is an enlarged sectional view of the pressure valve opening mechanism of FIG.

  As shown in FIG. 1 and FIG. 2, the rice cooker 1 according to the embodiment of the present invention has a pan 7 for containing a rice cooked product containing rice and water, an opening in which the pan 7 is accommodated, and an inside thereof. A rice cooker main body (hereinafter referred to as a main body) 2 having a heating means 5 for heating the pot 7 and heating the cooked rice, and a lid body 10 that is pivotally supported by one side of the main body 2 to cover the opening and make it closed. A pressure valve 13 that is attached to the lid 10 and adjusts the internal pressure in the pan 7, a pressure valve opening mechanism 18 that controls the opening of the pressure valve 13, and a display operation for displaying and selecting various rice cooking courses. And a control device 24 that controls the heating means 5 and the pressure valve opening mechanism 18 according to the selected rice cooking course to heat the cooked food in the pan 7 to a predetermined temperature and execute a series of rice cooking processes. ing.

  As shown in FIG. 5, a series of rice cooking processes are a water absorption process I in which a predetermined amount of water is absorbed by the rice in the pot, and an upright heating process II (IIS to IIL) in which the pot is heated and boiled after water absorption. , Boiling maintenance process III (IIIS-IIIL) in which rice starch is gelatinized and cooked while maintaining this boiling state, steaming process to remove excess water from cooked rice and further promote gelatinization, etc. It is a process that includes.

  As shown in FIG. 2, the main body 2 includes a bottomed box-shaped outer case 3 and an inner case 4 accommodated in the outer case 3, and a gap is formed between the outer case 3 and the inner case 4. A control circuit board or the like (not shown) constituting the control device 24 is disposed in the gap. The inner case 4 accommodates a pan 7 made of a deep bottom container. This pan 7 is formed of a clad material of aluminum and stainless steel. The inner case 4 is provided with a bottom heater 5b and a side heater 5a on the bottom 4a and side 4b, respectively, and a pan bottom temperature sensor 6 including a thermistor for detecting the pan bottom temperature is provided on the bottom 4a. . An electromagnetic induction coil (hereinafter also simply referred to as an IH coil) wound in an annular shape is used for the bottom heater 5b.

  Further, as shown in FIG. 1, the main body 2 is provided with a display operation unit 25 on the front surface thereof. As shown in FIG. 1, the display operation unit 25 has a display panel 8 on which various rice cooking selection courses and times are displayed, and a plurality of switch operation buttons provided on the left and right and below the display panel 8. 3a-3f, 9. These switch operation buttons 3a to 3f, 9 select the rice cooking / start button 3a for operating the rice cooker 1, the rice cooking reservation button 3b for making a rice cooking reservation, the cancel / warming button 3c for canceling the setting of rice cooking, etc., and the rice to be cooked A rice selection button 3d to select, a menu selection button 3e to select a rice cooking menu, a course button 3f to select a course, and a cross shift key 9 to select / determine a menu displayed on the display panel 8. These buttons and keys are operation buttons constituting a push button type switch, and various operations are performed by pressing these buttons or keys.

  As shown in FIG. 2, the lid 10 includes an inner lid 11 that closes the opening of the pan 7, an outer lid 12 that covers the entire opening of the main body 2, and the like. One side of the lid 10 is pivotally supported by the main body 2 by the hinge mechanism H, and the other side is locked by the locking mechanism 21 to the engaging portion of the main body 2.

  As shown in FIGS. 2 and 3, the inner lid 11 is provided with a negative pressure valve 17 and a pressure valve 13. The pressure valve 13 is opened by a pressure valve opening mechanism 18. The pressure valve 13 includes a valve seat 14a in which a valve hole 14b having a predetermined diameter is formed, a metal ball 15 placed on the valve seat 14a so as to close the valve hole 14b, and movement of the ball 15 It is comprised by the cover 14c which hold | maintains the ball | bowl 15 on the valve seat 14a by restrict | limiting. The pressure valve opening mechanism 18 is mounted on a cylinder 19a around which an electromagnetic coil is wound, a plunger 19b that moves in and out of the cylinder 19a by exciting the electromagnetic coil, and a tip of the plunger 19b. The operating rod 20 includes a spring provided between the one end of the cylinder 19 a and the operating rod 20.

  The pressure valve opening mechanism 18 is controlled by the control device 24. That is, when excitation to the electromagnetic coil is stopped based on a command from the control device 24, the plunger 19b jumps out of the cylinder 19a by the urging force of the spring and collides with the ball 15, and the ball 15 is pushed out in a predetermined direction. . By this extrusion, the ball 15 moves on the valve hole 14b and forcibly opens the valve hole 14b. When the electromagnetic coil is excited in the open state, the plunger 19b is drawn into the cylinder 19a, and the ball 15 closes the valve hole 14b by this drawing.

  The inner lid 11 is provided with a safety valve 16 that releases the pressure in the pan 7 to the outside when the steam pressure in the pan 7 rises to an abnormal pressure equal to or higher than a predetermined pressure. Further, a steam temperature sensor 23 (see FIG. 3) is attached to the inner lid 11.

  The inner lid 11 and the outer lid 12 are joined with a gap space S having a predetermined width therebetween. The outer lid 12 is detachably mounted with a storage tank 22 for temporarily storing a rice pad containing moisture discharged from the pan 7. The storage tank 22 includes a discharge cylinder 22a that discharges steam discharged through the pressure valve 13, a space 22b that temporarily stores a bowl, a steam port 22c that releases steam to the outside, and a tank valve. 221. The gap space S and the space 22b of the storage tank 22 are storage units that temporarily store rice balls. The rice cake is a sticky paste-like juice, and the paste-like juice contains a umami ingredient. If this rice cake is discharged out of the pan 7 as it is, the rice is not cooked deliciously. . Therefore, a storage tank 22 is provided for storing the rice bowl, and the rice basket is temporarily stored in the storage tank 22, and when the inside of the pan 7 is heated and the inside of the pan 7 becomes negative pressure, the storage tank 22 is stored. It can be cooked deliciously by returning the Neba in the pan 7.

  Next, with reference to FIG. 4, the structure of the control apparatus 24 for performing a predetermined rice cooking process is demonstrated. As shown in FIG. 4, the control device 24 includes hardware including a circuit board on which a CPU, a ROM, a RAM, and the like are mounted, and includes a rice cooking / start button 3a, a menu selection button 3e, a rice cooking reservation button 3b, and a cancel / heat retention. The buttons 3c, the pan bottom temperature sensor 6, the steam temperature sensor 23, and the like are connected to each other, and signals from these buttons and sensors are input to the CPU. In addition, a timer for measuring a predetermined time, a ROM, and a RAM are connected to the CPU. Further, heating means 5 such as a side heater 5a and a bottom heater (IH coil) 5b, a pressure valve opening mechanism 18, a display (display panel) 8, and the like are connected to the output section (driver). The ROM stores various rice cooking courses and programs for executing the rice cooking courses. The IH coil is connected to an inverter circuit, and the IH coil is controlled by this circuit.

  Next, the rice cooking process will be described with reference to FIGS. In addition, FIG. 5 is the temperature rise curve which showed the change of the temperature in the pan in a rice cooking process, FIG. 6 is the temperature rise curve which expanded a part of FIG. 5, FIG. 7 shows the time of a start-up heating process and a boiling maintenance process. 7A is a time table showing the time required for the start-up heating process and the boiling maintenance process in FIG. 5, and FIG. 7B is the start-up heating process and the boiling maintenance process of the prior art (FIG. 11). FIG. 8 (a) is a table showing the relationship between the immersion time and the elution amount of the solid content, and FIG. 8 (b) is a table showing the water absorption time to be set according to the difference in water temperature. It is.

  As shown in FIG. 5, the rice cooking process includes a water absorption process I in which a predetermined amount of water is absorbed by the cooked rice, a start-up heating process II in which the temperature in the pot is heated to boiling, and the pot is kept in a boiling state. Boiling maintenance process III to be performed, and a steaming process (not shown) for steaming the cooked rice after the boiling maintenance process.

  Among these rice cooking processes, the water absorption process I is divided into first and second water absorption processes I1 and I2 in which the rice absorbs a predetermined amount of water regardless of the amount of rice cooking in the pot. The rising heating process II and the boiling maintaining process III are small, medium and large in the amount of rice cooked in the pan, for example, processes IIS to IIL and IIIS corresponding to 0.5 cup, 3.0 cup and 5.5 cup rice. ~ IIIL. In these start-up heating steps IIS to IIL and boiling maintenance steps IIIS to IIIL, the temperature in the pan changes like curves TS, TN, and TL according to the amount of cooked rice. These temperature rise curves TS, TN, and TL are those before being changed. Among these temperature rise curves, the temperature rise curves TS and TL are adapted to follow the temperature rise curve TN when the reference temperature θS is exceeded. Changed to This change will be described later.

  In these rice cooking processes, the water absorption process I includes a first water absorption process I1 that absorbs a predetermined amount of water over a predetermined time using normal temperature water used for washing rice, etc. without operating the heating means. The first water absorption step I1 is divided into a second water absorption step I2 in which the heating means is operated to raise the temperature to a predetermined temperature θ1 and absorb the water. Since the water in the first water absorption step I1 is water at room temperature used for washing rice or the like, the water temperature varies depending on the seasons, and is usually low in winter and high in summer. This water is hereinafter referred to as room temperature water. Further, the predetermined temperature θ1 is, for example, 59 to 60 ° C.

  The water absorption time of the 1st water absorption process I1 changes with the temperature in the pan 7 at the time of rice cooking. That is, the water absorption time is set to a time during which the elution amount of rice solids, for example, starchy substances falls below a predetermined value when the rice is immersed in water at a predetermined temperature for a predetermined time. Fig.8 (a) has shown the elution amount by which solid content elutes from rice, when water temperature was changed and it immersed for 1 hour. The relationship between the water temperature and the amount of elution is obtained by experiments. As shown in FIG. 8A, when 100 g of rice is immersed in water at a water temperature of 21.6 ° C. for 1 hour, 0.53 g of solid content is eluted. Similarly, 0.73 g is eluted at 38.6 ° C, 0.84 g is eluted at 49.5 ° C, and 1.07 g is eluted at 58.6 ° C. When the amount of the solid content is large, for example, 1.0 g or more, the structure of the rice surface collapses, so the cooked rice becomes watery and has a poor taste. Therefore, the relationship between the water temperature and the water absorption time is set so that the elution amount per unit time of the solid content from the rice does not become 1% or more.

  The water absorption time of the first water absorption step I1 is set to be long when the water temperature is low and short when the water temperature is high. That is, as shown in FIG. 8B, when the water temperature in the pan 7 is low, for example, when the water temperature is 7 ° C. or less, the water absorption time is the longest 44 minutes, and when the water temperature is 8 to 12 ° C., the water absorption time is set. 40 minutes, and so on, 36 minutes when the water temperature is 13 to 17 ° C., 32 minutes when the water temperature is 18 to 22 ° C., 28 minutes when the water temperature is 23 to 27 ° C., 24 minutes when the water temperature is 28 to 32 ° C. Minutes, and when the temperature is 33 ° C. or higher, it is set to 20 minutes.

  The relationship between the water temperature and the water absorption time is stored in advance in the storage unit of the control device 24. The temperature in the pan 7 is detected by the pan bottom temperature sensor 6, and the timing of this detection is as shown in FIG. 5, with reference to FIG. It is preferable to detect at a time point a2 when 3 minutes have passed. This is because if the detection is performed immediately after the pan 7 is accommodated in the main body 2, the contact between the pan bottom and the sensor may be unstable, and accurate temperature detection may not be possible. is there. Therefore, by detecting the temperature when a predetermined time has elapsed, a more accurate temperature can be detected.

  By immersing in the first water absorption step I1 over a water absorption time corresponding to the temperature of room temperature water, sufficient water is absorbed in the rice in the pan 7, and the water content reaches a substantially saturated state. Next, in the second water absorption step I2 (time point a3), as a step before the transition to the next start-up heating step II, energization to the IH coil is turned on for a predetermined time, and the temperature in the pan 7 is set to a predetermined temperature. Water is absorbed for a predetermined time (a3 to a4) at θ1 (around 60 ° C.). This time is a transition period to the start-up heating process II, and since sufficient water is absorbed in the rice in the first water absorption process I1, this time is short, and further water is absorbed during this time. Few. Therefore, in the water absorption process I, particularly the first water absorption process I1, sufficient water is absorbed into the rice in the pan 7, so that heat conduction to the rice is good, and the cooked rice has no core. It will be delicious.

  In the next start-up heating process II, the energization to the heating means is turned on and the pressure valve 13 is closed, and the cooked rice after water absorption is heated to the boiling temperature. In the start-up heating process II, the pressure in the pan 7 is increased from atmospheric pressure to, for example, 1.2 atmospheres. Moreover, in this start-up heating process II, determination of the amount of rice cooking in a pan is performed.

  With reference to FIGS. 5-7, the determination of the amount of rice cooking in the rising heating process II and the rice cooking control after a rising heating process are demonstrated.

After absorbing normal temperature water in a predetermined amount of cooked rice in the pan 7 in the water absorption process I over a predetermined time and then moving to the start-up heating process II, as described above, different temperature change characteristics corresponding to the amount of rice cooked That is, when the amount of cooked rice is 3 cups, the temperature rise curve TN, when the amount of cooked rice is less than 0.5 cups, the temperature rise curve TS is presented, and when the amount of cooked rice is 5.5 cups, the temperature rise curve TL is presented. (See FIG. 5). On the other hand, when similarly measured in the prior art, temperature rise curves TS ′, TN ′, and TL ′ shown in FIG. 11 are exhibited. Tables (a) and (b) of FIG. 7 show the time required for the rising heating step II and the boiling maintaining step III in these temperature rise curves TS, TN, TL and TS ′, TN ′, TL ′, and the rising time. The time required to reach the reference temperature θs, for example, 90 ° C. in the heating process II is shown. This time is an example of an experimental value. The reference temperature θs is set in the range of the water absorption temperature θ1 or more and the temperature θ2 or less in the boiling maintenance step. From these data, the respective temperature rise curves TS ′, TN ′, TL ′ of the prior art are approximated, while the temperature rise curves TS, TN, TL of the embodiment are dispersed. In these temperature rise curves TS ′, TN ′, TL ′ and TS, TN, TL, when the time to reach a predetermined reference temperature θs (90 ° C.) is seen, in the prior art, the amount of rice cooked is 0.5 cup and 3 The difference is Δta ′ (6 seconds) at tS ′ (119 seconds, the same applies below) and tN ′ (125 seconds) for 0.0 cups, and tN ′ (125 for rice cups of 3.0 and 5.5 cups). Second) seconds and tL ′ (144 seconds), the difference is Δtb ′ (19 seconds), and the minimum cooking amount of 0.5 cup and the maximum 5.5 cup is tS ′ (119 seconds) and tL ′ (144 The difference is Δtc ′ (25 seconds) at the second), and the difference is small (at most 25 seconds or less) depending on the amount of cooking rice. On the other hand, in this embodiment, the difference is Δta (26 seconds) between tS (95 seconds) and tN (171 seconds), and the rice cooking amount is 3.0 cups and 3.0 cups. The difference is Δtb (116 seconds) for tN (171 seconds) and tL (287 seconds) for 5.5 cups, and tS (95 seconds) for 0.5 cups of minimum rice and maximum 5.5 cups. The difference is Δtc (192 seconds) at tL (287 seconds), and the difference is large (up to 192 seconds or less) depending on the amount of cooking rice. Therefore, the temperature rise curves TS ′, TN ′, TL ′ and TS, TN, TL of the prior art and the embodiment are dispersed from approximate ones depending on the amount of rice cooking, and as a result, the reference temperature θs (90 ° C. ) Reaches a large time difference, and the time to reach the reference temperature θs corresponds to the amount of cooked rice. Therefore, the amount of cooked rice can be determined by measuring the arrival time. That is, in the embodiment, the time to reach the reference temperature θs (90 ° C.), 0.5 cups of cooked rice when measuring tS (95 seconds), and 3.0 cups at tN (171 seconds) in the same manner. , TL (287 seconds), it can be determined to be 5.5 cups. The time to reach the reference temperature and the amount of cooked rice are obtained in advance through experiments, and the data is stored in the memory in the control device and is calculated by the cooked rice amount determination means during the rice cooking process. The amount determination in the start-up heating step II is performed in the first half of the start-up heating step, and based on the determination result, the heating in the boiling maintenance step III is then performed including the latter half of the start-up heating step II. Control is executed. In this embodiment, the reference temperature θs is set to 90 ° C., but is not limited to this value, and may be another set value. However, this set value must be below the boiling temperature. Moreover, although the determination of the amount of cooked rice was determined by the time to reach the reference temperature, other methods, for example, each temperature increase curve is dispersed, so use the slope of the curve to determine Also good.

  In this rice cooker 1, the length of time required for the start-up heating step II is an important factor that affects the taste of rice. It is known that if this time is too short, the rice will be hard, while if it is too long, the stickiness will be lost and the texture will be different, making it impossible for the user to cook rice (for example, Japanese Patent No. 2670720). See the official gazette). In order to perform favorite cooking, it is preferable to make the time required for the start-up heating process II constant. In general, rice cooker manufacturers are designed so that the amount of cooked rice is optimal between the minimum and maximum amount of cooked rice. In this embodiment, the description will be made on the assumption that the rice cooking conditions with the most intermediate rice cooking amount of 3.0 cups between the minimum rice cooking amount of 0.5 cups and the maximum rice cooking amount of 5.5 cups are optimal. The amount of cooked rice may be an amount other than the intermediate amount.

  As described above, when the amount is determined in the start-up heating process II, an accurate determination is possible. Based on this accurate determination result, the boiling maintenance process including the heating control in the latter half of the subsequent start-up heating process is performed. Heating control is performed. Subsequent heating control is performed by control which shifts to the start-up heating process IIN and boiling maintenance process IIIN corresponding to the intermediate rice cooking amount of 3.0 cups. This control becomes control which changed those temperature rise curves TS and TL so that the temperature rise curve TN may be followed from the time of passing the reference temperature (theta) S with respect to 0.5 cups and 5.5 cups of rice cooking. . That is, the temperature increase curve TN becomes a reference temperature increase curve.

  As shown in FIG. 6, the temperature rise curve TS is changed to TS2 from the time when the reference temperature θS is passed in order to shift the temperature rise curve TS1 to the temperature rise curve TN. Similarly, the temperature increase curve TL is changed to TL2 from the time when the reference temperature θS is passed in order to shift the temperature increase curve TL1 to the temperature increase curve TN. Looking at these shifts in terms of time, the time of the start-up heating step IIN and the boiling maintenance step IIIN in the intermediate rice cooking amount (3.0 cups) is IItN (352 seconds) and IIItN (332 seconds) from FIG. Therefore, on the basis of the time of each step in this intermediate rice cooking amount, the time of the heating up and boiling maintaining step in the rice cooking amount smaller or larger than this reference rice cooking amount is the same as or close to these times Change to That is, since the time required for the start-up heating process IIS and the boiling maintenance process IIIS in the minimum rice cooking amount (0.5 cup) is IItS (152 seconds) and IIItS (321 seconds), respectively, the reference temperature θs (90 ° C.) The subsequent time is changed to time IItN (352 seconds) and IIItN (332 seconds) of each step in the amount of intermediate rice cooking, that is, each time is lengthened.

  Therefore, in the minimum rice cooking amount (0.5 cup), the time of the start-up heating process IIS is changed to the time IItN in the intermediate rice cooked amount, and this start-up heating process IIS becomes a certain time, and the boiling maintaining process thereafter Since the heating is controlled for a time according to IIIN, rice is cooked under optimum conditions.

  Similarly, the time of the start-up heating process IIL and the boiling maintenance process IIIL in the maximum rice cooking amount (5.5 cups) is IItL (600 seconds) and IIItL (234 seconds), but after the reference temperature θs (90 ° C.) This time is shortened to match the amount of intermediate cooking rice. Therefore, in the maximum rice cooking amount (5.5 cups), the time of the start-up heating process IIL is changed to the required time IItN of the start-up heating process after the reference temperature θs (90 ° C.) in the intermediate rice cooking amount. This start-up heating process IIL may slightly exceed this time, but it is a time close to this time, and since the heating is controlled by the time of the boiling maintenance process IIIN, the rice is cooked under optimum conditions. The In addition, in this embodiment, although it shifted to the reference | standard temperature rise curve corresponding to intermediate | middle rice cooking amount after the boiling maintenance process III, you may perform rice cooking control corresponding to individual rice cooking amount unlike this.

  The rice cooking process will be described in detail with reference to FIGS. 5 and 8 to 10. 9 and 10 are flowcharts of the rice cooking process. In addition, although various rice cooking menus are displayed on the display panel 8, the rice cooking at the time of selecting a white rice course is demonstrated below.

  First, a predetermined amount of water and white rice are put in a pan 7 and the pan is accommodated in the inner case 4 of the main body 2. Therefore, the pot bottom temperature sensor 6 detects the pot bottom temperature (pot temperature) θ, and determines the water absorption time TA in the first water absorption step I1 based on the table of FIG. 8B (S01). The water absorption time corresponds to the temperature of normal temperature water. At this time, the pressure valve opening mechanism 18 is operated by the control device 24 to move the ball 15 and the pressure valve 13 is opened.

  When the water absorption time TA in the first water absorption process I1 is determined, the first water absorption process I1 is started (S02), and the time measurement of the water absorption time T1 is started by the timer (S03). When the water absorption time T1 reaches TA (S04), the first water absorption process I1 is completed and the process proceeds to the second water absorption process I2, and the time measurement of the water absorption time T2 of the second water absorption process I2 is started ( S05). When the 2nd water absorption process I2 is started, an inverter circuit will be started and electricity supply to an IH coil will be started. By this energization, a high frequency current flows through the bottom heater 5b, an eddy current is generated in the pan 7, the pan 7 generates heat, and heating of the cooked rice in the pan is started (S06). The pot bottom temperature is measured by the pot bottom temperature sensor 6, and the IH coil is energized until the measured value reaches a predetermined temperature of 60 ° C. (actually 59.9 ° C.) (S07). When the pan bottom temperature θ reaches 60 ° C., the power supply is stopped, and when the measured value reaches a predetermined temperature (θ2 = 59 ° C.), the power supply to the IH coil is resumed (S08). Then, it is detected whether or not the water absorption time T2 has reached a preset time TB required for the second water absorption step I2 (S09). When it is detected that the time TB has been reached, the process proceeds to the start-up heating step II. Transition (S10).

  In the next start-up heating process II, the electric power supplied to the IH coil is increased so as to be in a boiling state in a short time, high power heating is performed, and the pressure valve 13 is closed (S11). Control of high power heating and closing of the pressure valve 13 are performed by the control device 24. Based on a command from the control device 24, the pressure valve opening mechanism 18 pulls back the plunger 19b, whereby the ball 15 rolls on the valve hole 14b by its own weight to close the valve hole 14b, and the pressure valve 13 is closed. When high-power heating is started, determination of the amount of cooked rice in the pan 7 is started (S12). When the determination of the amount of cooked rice is started, it is determined whether the pan bottom temperature θ has reached 90 ° C. (S13), and the arrival time from the start of high power heating until the pan bottom temperature θ reaches 90 ° C. is measured. The amount of cooked rice is determined based on the arrival time (S14). That is, if the arrival time is long, the amount of cooking rice is large, and if the time is short, it is determined that the amount of cooking rice is small.

  When the determination of the amount of cooked rice is completed, the heating amount is adjusted based on the determined amount of cooked rice (S15 to S18). First, it is determined whether the amount of cooked rice is larger than the reference amount of cooked rice (S15). When the amount of cooked rice is greater than the reference amount of cooked rice, the power to be applied to the IH coil is further increased to increase the amount of heating (S16), the time required for the start-up heating process IIL is shortened, and the startup is the optimum time The length is the same as the time required for the heating step IIN.

  When it is determined that the amount of cooked rice is equal to or less than the reference amount of cooked rice (S15), it is next determined whether or not the amount of cooked rice is less than the reference amount of cooked rice (S17). When the amount of cooked rice is less than the reference amount of cooked rice, the heating power is decreased by reducing the power supplied to the IH coil (S18), the time required for the start-up heating process IIS is lengthened, and the start-up heating that is the optimal time The length is the same as the time required for the process IIN.

  When it is determined that the amount of cooked rice is equal to or greater than the reference amount of cooked rice (S17), the amount of cooked rice is the same as the reference amount, so the heating amount is not adjusted and the start-up heating process IIN is continued. In addition, if the amount of rice cooking is determined, according to the amount determination result, the set back time in the subsequent first steaming step and the steaming time in the third steaming step are also set.

  When the pan bottom temperature θ reaches 105 ° C., the process proceeds to the boiling maintenance step III. When the boiling maintenance process III is started (S19), the pressure in the pan 7 becomes a predetermined pressure equal to or higher than the atmospheric pressure, for example, about 1.2 atm, and the pan 7 is in a boiling state. From the initial stage of transition to the boiling maintenance step III, the control valve 24 operates the pressure valve opening mechanism 18 to forcibly open and close the pressure valve 13 a plurality of times. When the pressure valve 13 is forcibly opened, the pressure in the pan 7 is reduced from the predetermined boiling pressure (about 1.2 atm) to the vicinity of the atmospheric pressure at a stretch. In this bumping state, bubbles are generated in the pan 7 and the rice grains are stirred by the bubbles. As a result, the rice grains are uniformly heated and cooked. At the same time, a large amount of rice cake is generated. This rice cake enters the storage tank 22 through the valve hole 14b and the clearance space S of the pressure valve 13 together with the steam, and the steam is discharged to the outside from the steam port 22c. Other than that is stored in the space 22 b in the storage tank 22. This rice pad is also stored in the gap space S. When the pressure in the pan 7 decreases to near atmospheric pressure, the pressure valve 13 is closed again, the pressure in the pan 7 is increased, and the pressure valve 13 is repeatedly opened and closed several times. In addition, if time passes in this boiling maintenance process III, the amount of residual water in the pan 7 will reduce, a pressure fluctuation range will become small, and a bumping phenomenon will become weak. For this reason, forcibly opening the pressure valve 13 is effective when concentrated in the initial stage of the boiling maintenance process III. When the operation of opening the pressure valve 13 a plurality of times is finished, the forced opening of the pressure valve 13 by the pressure valve opening mechanism 18 is stopped, and the pressure valve 13 is closed. And the boiling state by a heater is continued and the pan bottom temperature K3 is measured. When the pan bottom temperature K3 reaches a predetermined temperature, for example, θ3 = 130 ° C., it is determined that the water in the pan 7 has dried up and the forced dry-up has been completed. And the process goes to the first steaming step (S20).

  When the process goes to the first steaming step, the timer starts measuring time T3. Then, the return time set for the amount of cooked rice is read out, and the time T4 is started by the timer. In the first steaming process corresponding to the return time, the energization of the IH coil is stopped, so the pressure in the pan 7 is reduced. At this time, the pressure valve 13 is closed. While this time T4 is being measured, the internal pressure in the pan 7 decreases to a negative pressure, the tank valve 221 and the negative pressure valve 17 are opened, and the rice bowl falls into the pan 7 from these valves. Most of the rice balls that have fallen into the pan 7 fall directly under the negative pressure valve 17, and the moisture contained in this portion of the rice bowl is high in moisture.

  When it is detected that the time T4 has reached a predetermined time, the first steaming process is completed and the process proceeds to the second steaming process (S21). If it transfers to a 2nd steaming process, electricity supply to an IH coil will be started and time-measurement of time T5 will be started by a timer. At this time, since the pressure valve 13 is closed, the pressure in the pan 7 rises to approximately 1.2 atmospheres. When it is detected that the time T5 has reached a preset time (for example, 48 seconds), the pressure valve 13 is opened, the second steaming process is completed, and the process proceeds to the third steaming process (S22). . By opening the pressure valve 13, the pressure P in the pan 7 is rapidly reduced from about 1.2 atmospheres to near atmospheric pressure. Due to this pressure change, the rice bowl causes a violent boiling phenomenon in the pan 7, a so-called bumping phenomenon, and the rice cake is diffused widely in the pan 7. The diffuse rice balls adhere to the rice and coat the rice grains.

  Thereafter, the steaming time (for example, 16 seconds) is read, the energization to the IH coil is turned on / off at a predetermined time interval, and steaming is performed over this steaming time. This steaming time varies depending on the amount of cooked rice. After the steaming time has elapsed, the energization of the IH coil is stopped for a predetermined time to perform the remaining steaming, and when the time T3 reaches 15 minutes, the entire steaming process is terminated and the process proceeds to the heat retaining process (S23). ).

  Although embodiment of this invention was demonstrated with the pressure type rice cooker, it is not limited to this pressure type rice cooker, A normal pressure type rice cooker may be sufficient. Further, the heating means is not limited to the IH heating method in which heating is performed by eddy current generated by the induction coil, and a heating plate in which a heater is mounted on the bottom of the pan or other heating methods may be used.

DESCRIPTION OF SYMBOLS 1 ... Rice cooker 2 ... Rice cooker main body 3 ... External cases 3a-3f, 9 ... Switch operation button 4 ... Internal case 5 ... Heating means 5a ... Side heater 5b ... Bottom heater (IH coil)
6 ... Pan bottom temperature sensor 7 ... Pan 8 ... Display panel 10 ... Cover 11 ... Inner lid 12 ... Outer lid 13 ... Pressure valve 16 ... Safety valve 17 ... Negative pressure valve 18 ... Pressure valve release mechanism 21 ... Lock mechanism 22 ... Storage tank 23 ... Steam temperature sensor 24 ... Control device 25 ... Display operation unit

Claims (7)

A pan for putting a predetermined amount of cooked rice, a heating means for heating the cooked rice in the pan, a temperature detection means for detecting the temperature in the pan, and an output from the temperature detection means are input to obtain a predetermined A control device that performs a rice cooking process, and the control device absorbs a predetermined amount of water into the cooked rice in the pan, and the rising heating that heats up the cooked rice cooked until the water is boiled In the electric rice cooker that executes a series of rice cooking steps including a boiling maintenance step for maintaining the inside of the pan in a boiling state after the step-up heating step, by determining the amount of rice cooking in the pan,
In the start-up heating step, a reference temperature increase curve corresponding to the reference rice cooking amount is set in advance,
Based on this amount determination, the control device determines the amount of rice cooked in the first half of the next heating up process after allowing room temperature water to be absorbed into the cooked rice in the pan for a predetermined time in the water absorption step. And the electric rice cooker provided with the control means which performs the heating control which shifts the temperature rise curve according to the amount of rice cooking to the said reference temperature rise curve from the second half of the said start-up heating process. In the boiling maintenance step in addition to the rising heating step, a reference temperature rise curve corresponding to the reference rice cooking amount is set in advance,
The said control apparatus shifts the temperature rise curve according to the rice cooking amount after completion | finish of the said start-up heating process to the said reference temperature rise curve, The electric rice cooker of Claim 1 characterized by the above-mentioned.   The control device is provided with an amount determination means for measuring the time from reaching the predetermined reference temperature after the transition to the rising heating step after the end of the water absorption step to determine the amount of rice cooking. The electric rice cooker of Claim 1.   The electric rice cooker according to claim 3, wherein the reference temperature is set to a temperature exceeding the temperature of the room temperature water.   The reference rice cooking amount is set to a substantially intermediate rice cooking amount of the maximum rice cooking amount and the minimum rice cooking amount, and the control device reduces the heating amount when the rice cooking amount is smaller than the intermediate rice cooking amount in the start-up heating step. And when it is large, the amount of heating is increased, and the temperature rise curve according to the amount of rice cooking is shifted to the said reference temperature rise curve, The electric rice cooker of Claim 1 or 4 characterized by the above-mentioned. In the water absorption step, set the water absorption time of the cooked rice corresponding to the temperature of room temperature water in advance,
The said control apparatus detects the temperature in the said pan at the time of water absorption start by the said temperature detection means, determines the said water absorption time, and performs the said water absorption process, The electric rice cooking of Claim 1 characterized by the above-mentioned. vessel.   The electric rice cooker according to claim 6, wherein the water absorption time is set short when the temperature of the room temperature water is high and long when the temperature is low.

Images