JP2012019915A - Rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rice cooker that is superior in energy-saving, and still can cook tasty rice, even though the inside of a rice cooker pot is maintained at a temperature of less than the boiling point to control the amount of evaporation, by making up for an efficient heat transfer due to a strong convection by boiling.SOLUTION: The rice cooker includes a forced convection unit 20 for causing forced convection in a pot 2 set in a rice cooker body 1. The rice cooker is configured to maintain the temperature of an object to be cooked therein at a predetermined temperature above the rice gelatinization starting temperature and below the boiling point. Meanwhile, a temperature maintaining step for creating a forced convection in the pot 2 by the forced convection unit 20, allows the object to be cooked in the pot 2 to be heated and stirred up even without a boiling convection, thereby enhancing the heat transfer from the pot 2 to the water and further to the rice, and facilitating the gelatinization of starch. Thus, it is possible to achieve a rice cooker that is superior in energy-saving, and still can cook tasty rice by spreading the glutinous liquid generated near the pot wall owing to the forced convection.

Description

  The present invention relates to a rice cooker that realizes a good taste while performing energy saving by heating below the boiling point.

  In general, after heating until the water in the pan boils in the rice cooking process, the boiling state is maintained to such an extent that it does not spill, thereby causing boiling convection due to the generation of intense bubbles of water vapor from the bottom of the pan due to boiling evaporation. The boiling convection greatly stirs the rice and water in the pan, promotes heat transfer from the pan to water and from water to rice, promotes gelatinization of the rice starch, and obtains cooked rice.

  However, when heating with boiling evaporation is performed in this way, it involves a phase transition from the liquid phase to the gas phase, and thus consumes a larger amount of energy than mere temperature maintenance. Then, the rice cooker which reduces steam and suppresses energy consumption by providing the process which controls the inside of a pan to the temperature which boiling evaporation does not occur has already been invented (for example, refer patent document 1).

  On the other hand, in the rice cooker of Patent Document 1, since boiling convection hardly occurs, the rice balls mainly generated at the bottom of the pan cannot concentrate enough to move to the top of the pan, and as a result, the top of the pan is The rice water retention film by the rice was not fully formed, and it became a hard rice, and at the bottom of the pan, it became a rice that remained damp.

  In contrast, in the first temperature maintenance step, the boiling point is maintained by heating to the boiling point, and stirring by boiling convection is performed so that the rice bowl generated mainly at the bottom of the pan is spread throughout the pan and continued. In the second temperature maintaining step, a rice cooker has already been invented that realizes energy saving without consuming a large amount of energy for latent heat of vaporization by lowering the temperature to below the boiling temperature (see, for example, Patent Document 2).

  FIG. 6 shows a rice cooking sequence diagram of the conventional rice cooker described in Patent Document 2. As shown in FIG. 6, after the water absorption step in which water is absorbed into the rice to such an extent that the shape of the rice does not collapse while heating moderately, the operation proceeds to the first temperature maintenance step, and the water in the pan is boiled. Within about 5 minutes after the start of boiling, water in which the dissolved components of the rice surface are concentrated (that is, rice bubbles) boil from the bottom to the top of the pan.

  Next, in the second temperature maintaining step, the heating amount is lowered so as to be able to maintain a temperature at which steam generation due to boiling can be suppressed. In particular, in order to effectively suppress the generation of steam, it is desirable to maintain the temperature at 98 ° C. or higher and lower than the boiling point.

JP-A-10-71072 Japanese Patent No. 4029352

  However, in the said conventional structure, since the evaporative convection was used as a means of the taste improvement by stirring in a pan, it had the subject that energy-saving performance will be reduced significantly.

  This invention solves the said conventional subject, and it aims at providing the rice cooker which improves the taste of cooked rice, without consuming energy largely as evaporation latent heat.

  In order to solve the conventional problems, a rice cooker according to the present invention includes a heating unit that heats a pan, a heating control unit that controls the heating unit according to a predetermined rice cooking sequence, and the cooking object in the pan. A rice cooker having forced convection means for forced convection, the forced convection in the pot by the forced convection means while maintaining the inside of the pan at a predetermined temperature above the gelatinization start temperature of rice and below the boiling point A maintenance process is provided.

  Rotating, sliding, and vibrating the pan rather than heating the pan and its cooking (mainly rice, water) to cause boiling convection to spread the pan all over the pan Thus, it has been found that the energy consumption is smaller and the action of stirring is larger when forced convection is performed.

  As a result, it is possible to spread the rice bowl generated mainly at the bottom of the pan by forced convection throughout the pan without boiling and evaporating to boil convection, without consuming large energy as latent heat of evaporation, A rice cooker that improves the taste of cooked rice can be provided.

  The rice cooker of the present invention can reduce boiling evaporation and reduce energy consumed by latent heat of vaporization to achieve large energy savings. The taste can be improved by spreading the nebane throughout the pot.

Side sectional view of the rice cooker in Embodiment 1 of the present invention. Rice cooking sequence diagram of rice cooker in Embodiment 1 of the present invention Rice cooking sequence diagram of rice cooker in Embodiment 1 of the present invention Rice cooking sequence diagram of rice cooker in Embodiment 1 of the present invention Correlation diagram of control temperature and water content of rice and the presence or absence of steam generated at that time Rice cooker sequence diagram of conventional rice cooker

  1st invention detects the temperature of the to-be-cooked object in the rice cooker main body, the pan equipped to the said rice cooker main body, the heating means which heats the said pan, the cover which covers the said rice cooker main body, and the said pan A rice cooker comprising: a temperature detecting means for performing heating; a heating control means for controlling the heating means in accordance with a predetermined rice cooking sequence according to an output of the temperature detecting means; and a forced convection means for forcing the food in the pan to be convected. A temperature maintaining step in which the inside of the pan is forced to convection by the forced convection means while maintaining the inside of the pan at a predetermined temperature above the gelatinization start temperature of the rice and below the boiling point, Evaporation can be reduced and energy can be saved greatly without consuming energy in the latent heat of vaporization. Also, the diffusion of the rice cake, which is the element of the water-retaining film, by the action of forced convection throughout the pan, To prevent overheating It is possible to provide a cooker which improved the rose rice taste cooked Te.

In particular, the second invention reduces boiling evaporation by setting the predetermined temperature of the first invention above the temperature at which the water content of cooked rice can be 60% or more and less than the boiling point. It is possible to save energy without consuming energy in the latent heat of vaporization, and the diffusion of the rice cracker, which is the element of the water retaining film, by the action of forced convection throughout the pan and the overheating of the rice on the pan skin It is possible, and it is possible to provide a rice cooker that improves the taste of cooked rice by providing a step of maintaining the water content of the cooked rice at a temperature equal to or higher than 60%.

  In the third invention, in particular, the predetermined temperature of the first or second invention is set to 98 ° C. or more and lower than the boiling point, so that boiling evaporation does not occur and energy is not consumed in the latent heat of evaporation and energy is largely saved. In addition, it is possible to diffuse the rice cracker, which is an element of the water retaining film by the action of forced convection, to the whole pan and to prevent overheating of the rice on the pan skin, and maintain the process at 98 ° C. or higher. By providing it, it is possible to provide a rice cooker that can improve the taste of cooked rice and shorten the cooking time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a side sectional view of a rice cooker according to the first embodiment of the present invention.

  In FIG. 1, the rice cooker main body 1 is formed in a substantially cylindrical shape having an upper surface opened. A protective frame 9 that is a pan storage portion is disposed inside the rice cooker body 1, and a pan 2 having a water level line drawn on the inner peripheral surface is detachably disposed in the protective frame 9.

  A pan bottom heating coil 5a for heating the pan 2 is disposed outside the bottom surface of the protective frame 9, and a pan side heating coil 5b is disposed outside the side surface. The pan bottom heating coil 5a and the pan side heating coil 5b may be heaters instead of the heating coils. The heating means 5 includes the pan bottom heating coil 5a, the pan side heating coil 5b, and an inner lid heating coil (heater) 5c described later.

  A motor 20 is fixed to the rice cooker body 1 as a forced convection means, and the pan 2 is rotated via a gear 21. The portion of the pot 2 that contacts the gear 21 is knurled so that it can be smoothly connected to the gear 21. Or it is good also as a structure which can rotate the pan 2 with a frictional force by using the gear 21 as a roller.

  By rotating the pan 2, a rotational force is applied to the rice and water that are to be cooked in the pan 2, thereby generating forced convection.

  The forced convection means is not limited to the above configuration. For example, a vibrating element containing ultrasonic waves is brought into contact with the pan 2 to cause vibration, a stirring bar (stirring blade) is operated in the pan 2, the pan 2 is swung like a precession, and horizontal and vertical directions. Various movements and means, such as reciprocating, can be considered.

  A lid 3 is attached to the upper portion of the rice cooker body 1 so as to be freely opened and closed. One end of the lid 3 is pivotally supported by a hinge shaft 3a at the rear portion of the protective frame 9, and is urged by a rotation spring 3b. The other end of the lid 3 is engaged with a hook button 1a attached to the front of the protective frame 9 to prevent the lid 3 from being opened. When the hook button 1a is engaged with the lid 3, the lid 3 is held by the hook button 1a without opening and is in a closed state.

  An inner lid 4 having a steam port 4b for discharging steam generated in the pan 2 during rice cooking and heat insulation is disposed at the lower portion of the lid 3, and an inner lid heating coil (heater) for heating the inner lid 4 is disposed on the upper portion. ) A cylindrical steam cylinder 10 that is in communication with 5c and the outside of the rice cooker body 1 is disposed.

A steam port packing 4 c is provided between the steam cylinder 10 and the inner lid 4 so as to surround the periphery of the opening of the steam cylinder 10 to prevent the steam from the steam port 4 b from flowing into the lid 3. Moreover, the inner cover packing 4a which contact | abuts on the outer peripheral part of the inner cover 4 and the upper surface of the flange part 2a of the pan 2 is arrange | positioned, and the vapor | steam which generate | occur | produces in the pan 2 during rice cooking and heat insulation is from steam outlet 4b. Prevents leakage to the outside.

  It is assumed that the frictional resistance between the pan 2 and the inner lid packing 4 a in the closed state of the lid 3 is smaller than the force with which the gear 21 or the roller drives the pan 2. Therefore, when the forced convection means such as the motor 20 is driven (rotated), the pan 2 is driven (rotated) against the frictional force of the inner lid packing 4a.

  A temperature sensor unit 8 including a contact portion 13 that comes into contact with the substantially center portion of the bottom of the pan 2 and a temperature sensor 7 that measures the temperature of the contact portion 13 is urged by a spring 15 so as to approximate the bottom of the pan 2. The temperature of the pan 2 can be detected by heat conduction in contact with the center. By detecting the temperature of the pot 2, the temperature of the food to be cooked in the correlated pot 2 can be estimated. Therefore, the temperature sensor unit 8 is used as temperature detection means.

  Inside the rice cooker body 1 is arranged a control means 6 having a heating control means 6a for controlling the heating means 5 in accordance with a predetermined rice cooking sequence (described later) according to the output of the temperature sensor unit 8 which is a temperature detecting means. Yes.

  About the rice cooker comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  FIGS. 2-4 shows the rice-cooking sequence figure of the rice cooker in the 1st Embodiment of this invention.

  First, a predetermined amount of rice and water is put into the pot 2 after the rice washing treatment and stored in the rice cooker body 1, and the start of rice cooking is instructed by the operation input display unit 12 installed on the surface of the lid 3.

  As shown in FIGS. 2 to 4, the rice cooking process is roughly divided into four processes.

  The temperature in the pot 2 is increased to a water absorption acceleration temperature (for example, 60 ° C.) that is equal to or lower than the gelatinization temperature of rice to promote water absorption of the rice. “Cooking process” for heating to a predetermined temperature below the boiling point above the boiling point, and maintaining at the predetermined temperature by detecting the arrival of the predetermined temperature with a pan temperature detecting means during the “cooking process” Finally, the moisture at the bottom of the pan 2 evaporates and the temperature of the pan 2 greatly exceeds the boiling point of the water, so that dry-up is detected, and the transition to the “spotting process” is made.

  In the “spotting process”, since almost no moisture remains on the bottom of the pan 2, the rice is heated with a weak heating power so as not to scorch, and only excess moisture is blown away while gelatinizing the rice.

  The rice cooking process is completed by the completion of the “spotting process” and the process proceeds to heat insulation.

  Here, if the cooking temperature in the pan 2 is raised to the boiling point in the “cooking step” and the “temperature maintaining step”, violent evaporation occurs from the bottom of the pan 2 due to boiling, and the cooking object is convected to make the pan 2 The rice balls produced at the bottom were spread throughout the pan 2, and the heat transfer from the pan 2 to the water and water to the rice was promoted by convection to gelatinize the rice. However, large energy consumption due to latent heat of vaporization is indispensable to maintain and maintain intense boiling.

  So, in this Embodiment, rice is fully gelatinized by keeping temperature at 70 degreeC or more which is the minimum temperature which rice gelatinizes, and lengthening temperature maintenance time compared with the rice cooking with normal boiling. It is possible to achieve significant energy-saving rice cooking without boiling boiling.

  Moreover, by reproducing the intense convection due to boiling by forced convection means such as rotating the pan 2 with the motor 20, the rice balls are spread throughout the pan and the heat transfer to the rice is improved without causing boiling. Good-tasting cooked rice can be obtained.

  FIG. 5 shows a correlation diagram between the control temperature and water content of rice and the presence or absence of steam generated at that time.

  In FIG. 5, when the controlled temperature of rice is 65 ° C., the moisture content of rice is a low value of 30%, but at 70 ° C., the moisture content rapidly increases and the moisture content of rice rises to 50%. This is considered to be because when the temperature was raised to 70 ° C. or higher, the cell wall on the surface of the rice hindering the water absorption of the rice softened, and the water absorption of the rice rapidly increased.

  When the control temperature is further increased to 80 ° C., the moisture content increases to 55%, and good cooked rice that is softer than when the control temperature is 70 ° C. can be obtained. Furthermore, when the control temperature is raised to 95 ° C., the water content increases to 60%, and the obtained cooked rice is the same as that cooked by the conventional method.

  Therefore, as shown in FIG. 3, by keeping the temperature of the cooked food in the pan at 95 ° C. or higher in the “temperature maintenance step”, the moisture content of the cooked rice is increased to 60% or more equivalent to that of cooked rice with normal boiling. can do.

  In addition, as shown in FIG. 4, it is possible to cook rice in the same time as cooking with normal boiling by keeping the cooking in the pan at 98 ° C. or higher in the “temperature maintaining step”, but the evaporation amount is 95 ° C. It is slightly increased compared to the case where it is maintained.

  By providing a “temperature maintenance process” for forced convection while maintaining the inside of the pan 2 below the boiling point as described above, boiling evaporation can be suppressed and energy can be saved significantly. It is possible to provide a rice cooker that obtains tasty cooked rice by spreading the whole of the pan and improving the heat transfer to the rice.

  As mentioned above, since the rice cooker concerning this invention suppresses boiling evaporation and can cook rice with good taste, it can be applied to other uses such as cooking equipment.

DESCRIPTION OF SYMBOLS 1 Rice cooker main body 1a Hook button 2 Pan 2a Flange part 3 Lid 3a Hinge shaft 3b Rotating spring 4 Inner lid 4a Inner lid packing 4b Steam port 4c Steam port packing 5 Heating means 5a Pan bottom heating coil 5b Pan side heating coil 5c Inside Lid heating coil (heater)
6 Control means 6a Heating control means 7 Temperature sensor 8 Temperature sensor unit 9 Protection frame 10 Steam cylinder 12 Operation input display part 13 Contact part 15 Spring 20 Motor 21 Gear

Claims (3)

A rice cooker body, a pan equipped on the rice cooker body, a heating means for heating the pan, a lid covering the rice cooker body, a temperature detection means for detecting the temperature of the cooking object in the pan, A rice cooker comprising heating control means for controlling the heating means according to a predetermined rice cooking sequence according to the output of the temperature detection means, and forced convection means for forcibly convection the food to be cooked in the pan, A rice cooker comprising a temperature maintaining step of forcing convection in the pan by the forced convection means while maintaining the inside of the pan at a predetermined temperature not less than the gelatinization start temperature of rice and less than the boiling point. 2. The rice cooker according to claim 1, wherein the predetermined temperature is equal to or higher than a temperature at which the water content of the cooked rice can be 60% or higher and lower than the boiling point. The said predetermined temperature is 98 degreeC or more and less than a boiling point, The rice cooker of Claim 1 or 2 characterized by the above-mentioned.

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