JP2013081501A - Rice cooker and rice cooking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure rice cooker that eliminates uneven rice cooking by preventing uneven cooking from occurring during a start-up heating process, and improving heat transfer during a boiling process.SOLUTION: The pressure rice cooker includes: a pressure valve 13 for blocking a communication area between a pot 10 and the outside air; a pressure valve opening mechanism 19 attached to the pressure valve, and for forcibly opening the pressure valve from a closed state; and a control means 30 for controlling the heat amount of a heating means, and controlling the opening and closing of the pressure valve by the pressure valve opening mechanism. The pressure rice cooker cooks rice by applying pressure during a start-up heating process among a series of rice cooking processes. The control means controls the pressure valve opening mechanism to forcibly open the pressure valve so that the inner pressure of the pot pressurized during the start-up heating process is immediately reduced by at least 0.1 atmospheric pressure or higher, thereby causing an immediate pressure change in the pot to generate a convention flow to agitate the object to be cooked in the pot.

Description

  The present invention relates to a pressure rice cooker that cooks delicious rice in a short time by cooking rice in a pressurized state.

  Electric rice cookers are now one of the necessities in general households, and various types of rice cookers have been developed. This electric rice cooker is roughly classified into a normal pressure type that cooks the pressure in the pan at almost normal pressure and a pressure type that raises the pressure to a pressure equal to or higher than atmospheric pressure and cooks rice.

  For example, Patent Document 1 below discloses a pressure rice cooker that cooks rice by cooking at a pressure higher than atmospheric pressure during rice cooking. FIG. 11 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process of the pressure rice cooker described in Patent Document 1 below.

  This pressure-type rice cooker has a pan in which a cooked rice containing an opening and rice and water is placed, and a rice cooker main body having a heating means in which the pan is housed and heating the cooked rice in the pan. A lid for closing the opening of the pan and the rice cooker body, a pressure valve for adjusting the pressure in the pan, a pressure valve opening mechanism for forcibly opening the pressure valve, and a heating amount of the heating means are controlled to be predetermined. And a control device for controlling the opening of the pressure valve.

  The rice cooking process consists of a water absorption process in which a predetermined amount of water is absorbed by the cooked rice in the pan, a rising heating process in which the temperature is raised until boiling after this water absorbing process, and a boil maintained in a boiling state after this rising heating process. There are a maintenance process, a steaming process of steaming for a predetermined time after the boiling maintenance process, and a heat retention process of keeping the temperature at a predetermined temperature.

  When the water absorption process is completed in the start-up heating process, the control device heats the pan with full power to raise the temperature and closes the pressure valve to increase the pressure in the pan to 1.2 atm. In the next boiling maintenance step, the pressure valve is forcibly opened at least once, and the pressure in the boiling pan is lowered to the vicinity of atmospheric pressure at once, and the rice grains in the pan are stirred. .

  According to this pressure type rice cooker, the cooked rice is efficiently stirred during the boiling maintaining step, so that delicious rice can be cooked without uneven cooking.

JP 2004-344568 A

  However, in the conventional configuration, the pressure in the pan is lowered during the boiling maintenance process to generate a bumping phenomenon, so that rice unevenness during the boiling maintenance process can be suppressed and cooked. At this stage, heating unevenness occurred in the pan, and as a result, the cooking unevenness was not completely eliminated.

  This type of pressure rice cooker moves to the start-up heating process when the water absorption process is finished, closes the pressure valve in this start-up heating process, starts full power feeding to the heating means, and rapidly heats the inside of the pan Then, the temperature is raised until boiling, and the pressure is increased to atmospheric pressure or higher (1.2 atm in the above rice cooker). By this temperature rise and pressure increase, the cooked rice in the pan is heated to high heat by the heating means provided at the bottom of the pan, and temperature unevenness in the pan is likely to occur, and rice in the area close to the inner wall of the pan before boiling Was heated enough, but the rice in the upper center from the center of the pan, which was far from the inner wall, was under-heated and had a structure in which uneven heating (uneven cooking) was likely to occur.

  In addition, the rice in the area near the inner wall of the pan is overheated and starch gelatinization begins before the rice in the center, the rice bonds together, and boiled foam generated during the boiling maintenance process It was difficult to penetrate directly from the bottom of the pan, and heat was not transmitted. Especially when cooking large-capacity rice, it was a structure in which cooking unevenness was likely to occur near the upper center of the pan.

  The present invention solves the above-described conventional problems, and suppresses uneven cooking in the start-up heating process, improves heat transfer during the boiling maintenance process, and eliminates uneven cooking. The purpose is to provide a vessel.

  In order to achieve the above object, a pressure rice cooker according to the present invention comprises a pan into which a predetermined amount of cooked rice containing water and rice is charged, an opening for housing the pan, and a cover in the pan. A rice cooker main body having a heating means for heating the cooked rice, a lid for closing the opening of the pan and the rice cooker main body, a pressure valve for communicating or shutting off the inside of the pan and the outside air, and the pressure valve And a pressure valve opening mechanism for forcibly opening the pressure valve from a closed state, and a control means for controlling the heating amount of the heating means and controlling the opening and closing operation of the pressure valve by the pressure valve opening mechanism. In a pressure rice cooker that cooks rice in a pressurized state during the start-up heating process in a series of rice cooking processes, the control means is configured to increase the pressure in the pan during the start-up heating process. The pressure valve is forcibly opened by the pressure valve opening mechanism. Control so that stirring convection of the cooked food in the pan occurs by lowering the pressure in the pan during heating by reducing it to at least 0.1 atm. It is characterized by doing.

  According to the present invention, when cooking rice by raising the pressure in the pan at the time of cooking, the pressure in the pan is reduced by communicating the inside of the pan that has been pressurized immediately before boiling from the initial heating stage in the start-up heating step and the atmosphere. Because of the momentary pressure change when the pressure in the pan is released and returns to the atmospheric pressure, bubbles are generated from the bottom of the pan, and the cooked rice is stirred and convected in the pan, in the region close to the inner wall of the pan. The to-be-cooked food and the to-be-cooked food in the center cause convection. As a result, sufficient heat is applied to the whole rice grain, and uniform heating in the start-up heating process is performed. And the rice that started to gelatinize on the inner wall of the pan and became a film, the film was broken by the momentum of the foam, the boiling bubbles generated continuously in the boiling maintenance process of the next process became easy to be transmitted to the center part, enough It can be heated and cooking unevenness can be eliminated.

  As described above, the present invention forcibly opens the pressure valve forcibly increasing the pressure in the pan in the pressure rice cooker that cooks rice in a pressurized state during the start-up heating process in a series of rice cooking processes. By causing the pressure to drop, the pressure changes instantaneously, bubbles are generated from the bottom of the pan, and stirring convection of the cooked rice in the pan causes hot water and a central portion in the area near the inner wall of the pan. As a result, sufficient heat is applied to the whole rice grains and uniform heating in the start-up heating process is performed. In addition, the rice that has been gelatinized at the inner wall of the pan and joined together as a film breaks the film due to the momentum of the foam, and the bubbles that are continuously generated in the boiling maintenance process of the next process are easily transmitted to the central part, and the subsequent processes It will be easy to heat enough.

FIG. 1 is a front view of a pressure rice cooker according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the pressure rice cooker of FIG. 1 cut in the longitudinal direction. 3 is an enlarged cross-sectional view in which the pressure valve opening mechanism portion of FIG. 2 is enlarged. FIG. 4 is a block diagram of a control device housed in the pressure rice cooker of FIG. FIG. 5 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process according to the first embodiment of the present invention. FIG. 6 is a flowchart up to the start-up heating process of the white rice / usually cooked rice course executed by the control device of FIG. FIG. 7 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process according to the second embodiment of the present invention. FIG. 8 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process according to the third embodiment of the present invention. FIG. 9 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process according to the fourth embodiment of the present invention. FIG. 10 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process according to the fifth embodiment of the present invention. FIG. 11 is a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process of the pressure rice cooker of the prior art.

  1st invention is a rice cooker main body which has a pan into which a predetermined amount of cooked rice containing water and rice is charged, an opening for housing the pan, and a heating means for heating the cooked rice in the pan. A lid that closes the opening of the pan and the rice cooker body, a pressure valve that communicates or shuts off the inside of the pan and the outside air, and controls the heating amount of the heating means and by the pressure valve opening mechanism A control means for controlling the opening operation of the pressure valve, a water absorption step for controlling the heating means and the pressure valve opening mechanism to absorb the cooked rice in the pan, and a rising heating for raising the temperature until boiling In the pressure-type rice cooker provided with the control apparatus which performs the rice cooking process including the boiling maintenance process which maintains a process and a boiling state, and the menu setting means which sets the rice cooking menu and performs the said rice cooking process, after the said water absorption process completion | finish In the above-mentioned heating process The pressure valve is closed and the inside of the pan is raised to atmospheric pressure or more to execute the rising heating step, and the control means has sufficient moisture in the cooked rice in the pan in the rising heating step. During a period of time, the pressure valve is opened by the pressure valve opening mechanism to reduce the pressure in the pan at least 0.1 at a time, the pressure in the pan during heating is reduced at a stroke, and a pressure change is instantaneously generated in the pan. By the stirring convection of the cooked rice, the cooked rice in the region near the inner wall of the pan and the cooked rice in the center cause convection, and as a result, sufficient heat is applied to the whole rice grain, and the above-described heating process Is uniformly heated. And the rice that started to gelatinize on the inner wall of the pan and became a film, the film was broken by the momentum of the foam, the boiling bubbles generated continuously in the boiling maintenance process of the next process became easy to be transmitted to the center part, enough Can be heated.

  In the second invention, in particular, when the amount of cooked rice is large, the pressure in the pan during heating is reduced at a stroke at least once for the opening operation of the pressure valve in the rising heating step of the first invention. By causing the atmospheric pressure to change instantaneously and causing the stirring convection of the cooked rice in the pan, particularly, the stirred convection of the cooked rice in the pan during large-capacity rice cooking can be sufficiently performed.

  In the third invention, in particular, the detection value of the steam sensor attached to the lid body in the rising heating process is a predetermined setting reference for the opening operation of the pressure valve in the rising heating process of the first invention. By opening the pressure valve when it becomes a value, or when the detected value of the steam sensor at the end of the water absorption process is equal to or higher than a predetermined temperature rise set value in the startup heating process, The opening operation of the pressure valve can be performed at an optimal timing.

  In the fourth aspect of the invention, in particular, the detection value of the pressure sensor attached to the lid in the rising heating step is a predetermined pressure value when the pressure valve is opened in the rising heating step of the first invention. When the above is reached, the pressure valve can be opened at an optimal timing by opening the pressure valve.

  In the fifth aspect of the invention, in particular, the pressure valve opening mechanism of the first aspect of the invention allows the pressure valve to be opened multiple times in a menu in which the water absorption process is longer than the standard rice cooking menu, thereby enabling the inner wall of the pan to be opened. In the past, the rice that has started to gelatinize and become a membrane is broken by the momentum of the bubbles, and the membrane breaks due to the momentum of the bubbles. I can do it.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, embodiment shown below illustrates the pressure type rice cooker for materializing the technical idea of this invention, Comprising: This invention is not intended to specify this pressure type rice cooker. Other embodiments within the scope of the claims are equally applicable.

(Embodiment 1)
With reference to FIG. 1, FIG. 2, the outline | summary of the pressure type rice cooker which concerns on embodiment of this invention is demonstrated. 1 is a front view of a pressure rice cooker according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the pressure rice cooker of FIG. 1 cut in the longitudinal direction.

  The pressure-type rice cooker 1 is a pressure-type rice cooker that cooks rice by raising the pressure in the pan to atmospheric pressure or higher, for example, about 1.2 atm. Note that this pressure is not limited to 1.2 atm, and may be higher. As shown in FIG. 2, the pressure rice cooker 1 has a large pot 10 in which rice and water containing rice and water are put, an opening in which the pot 10 is accommodated above, and the pot 10 heated inside. A large rice cooker body (hereinafter simply referred to as “main body”) 2 having a pan bottom heater H1 and a side heater H2 for heating the cooked rice, and an opening of the main body 2 and the pan 10 supported by one side of the main body 2 And a large lid 11 having a lock mechanism 16 and a lid heater H3. Hereinafter, each structure of this rice cooker is demonstrated.

  First, the main body will be described mainly with reference to FIG.

  The main body 2 includes an outer case 3 and an inner case 4 that is accommodated in the outer case 3 and accommodates the pan 10 therein. A predetermined gap is provided between the outer case 3 and the inner case 4. And a control circuit board or the like (not shown) constituting the control device 30 (see FIG. 4) is disposed in the gap. In addition, although not shown, a cooling fan for forcibly cooling the inside of the main body and a motor for driving the cooling fan are accommodated in the gap.

  As shown in FIG. 2, the pan 10 has an opening 10a on the upper side and a flange-like flange portion 10b on the periphery of the opening, and is formed of a large container that can cook a predetermined amount of rice, for example, about 3 cups. Yes. The pan 10 has an inner layer made of a material having high thermal conductivity, such as copper or aluminum, and an outer layer made of a magnetic material, such as stainless steel, and the surface of the inner layer is covered with a fluororesin or the like. ing.

  The main body 2 includes a display operation unit 5 (see FIG. 1) for performing operations such as start of rice cooking, timer reservation, and heat retention, and a pan bottom heater H1, a side heater H2 and a lid according to a rice cooking start signal from the display operation unit 5 A heating circuit composed of a heater H3 and a control circuit board (not shown) for controlling the pressure valve opening mechanism 19 are provided.

  The outer case 3 is formed of a decorative box having a larger outer shape than the inner case 4. The exterior case 3 is provided with an opening 31 above it. Since the outer case 3 accommodates the inner case 4 inside, and a gap is provided between the cases 3 and 4 to dispose the control circuit board and the like, the opening 31 of the outer case is the opening of the inner case 4. It is larger than 41 and its shape is substantially elliptical. In addition, the opening 41 of the inner case is substantially circular like the opening of the pan 10. Further, as shown in FIG. 1, a display operation unit 5 is provided on the front surface of the outer case 3. The display operation unit 5 includes an operation panel 5a provided with various operation keys and a display panel 5b for displaying a setting state set by the operation switches. The operation panel 5a is provided with a start key, a menu key, a reservation key, a heat retention key, and the like. On the display panel 5b, rice varieties to be cooked, such as white rice / normal rice cooking courses, and other rice cooking courses, such as brown rice cooking courses, are displayed and can be selected by a menu key.

  The inner case 4 has a substantially bowl-shaped bottom part 4a having a predetermined diameter and a cylindrical side wall part 4b erected for a predetermined length from the periphery of the bowl-shaped bottom part 4a. The upper part is opened, and the container is made of a size that accommodates the pot 10 through the opening 41, and is formed of a heat-resistant resin molding. A pot bottom heater H1 made of an electromagnetic induction coil wound in a donut shape is fixed to the bowl-shaped bottom portion 4a by a support (not shown). The pot bottom heater H1 is, for example, 1200 watts. By this electromagnetic induction coil, an eddy current is generated in the pan 10 and the pan itself self-heats. The bottom 4a is provided with a bottom sensor Sen1 made of a thermistor or the like that detects the pan bottom temperature. The bottom sensor Sen1 detects the temperature of the bottom of the pan 10 to detect the amount of rice cooked in the pan 10 and the like. Moreover, the cylindrical side wall part 4b has the attachment part 42 with which the side surface heater body H2 is mounted | worn on the inner peripheral wall surface, ie, the inner peripheral wall surface of the side in which the pan 10 is accommodated. This attachment part 42 is between the upper opening 41 and the bottom part 4a, and is a recessed hole that is recessed to a predetermined depth from the inner peripheral wall surface on the side where the pan 10 is accommodated toward the outer peripheral wall surface. A side heater H2 is mounted in the recessed hole.

  As shown in FIG. 2, the openings 31 and 41 of the outer case 3 and the inner case 4 are covered with the frame cover 6 with the frame cover reinforcing member 7 interposed therebetween. The frame cover 6 has an opening that is slightly larger than the opening 10a of the pan 10 inside, and a bowl-shaped peripheral portion that extends outward from the opening and covers the openings 41 and 31 of the inner case 4 and the outer case 3. It is made of a substantially elliptical plate-like body having a predetermined thickness, and is formed of a resin molded body. The periphery of the opening on the surface of the frame cover 6 is a placement portion on which the flange portion 10b of the pan 10 is placed. The mounting portion is provided with a locking member 8 that locks the locking mechanism 16 of the lid 11 at one end. The locking member 8 includes a locking piece 8b made of a metal plate to which the locking claw 17a of the locking mechanism 16 is locked, and a base that is positioned above the locking piece 8b and fixes the locking piece 8b. The base 8a, the locking piece 8b, the frame cover 6, and the frame cover reinforcing member 7 to be described later are formed with screw holes, which are laminated and screwed. On the base 8a, the flange portion 10b of the pan 10 is placed. The base 8a is formed of a heat resistant resin material. Moreover, the mounting part is provided with a hinge member 9 that pivotally supports the pedestal 8a 'on which the flange portion 10b of the pan is placed at the same level as the pedestal 8a and the lid 11 at the other end. The hinge member 9 has a short first mounting portion 9a fixed to the frame cover 6, and a relatively long second mounting portion 9b on which one end of the lid 11 is pivotally supported. It is substantially L-shaped and is formed of a rigid member. This member is formed of a thick metal material, for example, a die-cast molded body made of stainless steel, aluminum or aluminum alloy having a thickness of about 2 to 5 mm, and a large and heavy lid. Reinforced to withstand the pressure rise in the pan. Screw holes are formed in the pedestal 8a ', the frame cover 6, the hinge member 9, and the first mounting portion 9a, and these are stacked and screwed. On the base 8a ', the flange portion 10b of the pan 10 is placed.

  The configuration of the lid will be described with reference to FIGS. 2 and 3. FIG. 3 is an enlarged cross-sectional view in which the pressure valve and the pressure valve opening mechanism in FIG. 2 are enlarged.

  As shown in FIG. 2, the lid 11 includes an inner lid 12 that closes the opening 10 a of the pan 10, and an outer lid 15 that is positioned above the inner lid 12 and closes the opening of the main body 2. The outer lid 15 is formed with a recess 24 ′ for mounting the storage tank 24, and the periphery is covered with a decorative cover 18. Further, the outer lid 15 is constituted by a solid lid frame.

  As shown in FIGS. 2 and 3, the inner lid 12 is formed of a large disc-shaped lid having a size for closing the large pan opening 10 a, and the pressure valve 13 and the pressure in the pan 10 are abnormal in the upper part. A safety valve V1 and the like are provided for releasing the steam in the pan 10 to the outside when it rises. A seal member that is in contact with the opening 10 a of the pan 10 is attached to the outer periphery of the inner lid 12. Further, a locking member (not shown) is provided on the outer periphery of the inner lid 12 so as to protrude outward and be detachably locked to a fixing means of the outer lid 15. As shown in FIG. 3, the pressure valve 13 includes a valve seat 13a in which a valve hole 131 having a predetermined diameter is formed, a metal ball 14 placed on the valve seat 13a so as to close the valve hole 131, A cover 13b that restricts the movement of the metal ball 14 and holds it on the valve seat 13a. The metal ball 14 has a predetermined weight and closes the valve hole 131 by its own weight.

  The outer lid 15 has a locking mechanism 16 for the lid 11 at one end, a pressure valve opening mechanism 19 at a position adjacent to the locking mechanism 16, and the outer lid 15 is supported by the hinge member 9 at the other end and is opened. A spring pivot mechanism (not shown) is provided to support the movement and to keep it open. The outer lid 15 is provided with a lid heater H3. Further, a recessed portion 24 ′ to which a storage tank 24 is mounted is provided between the pressure valve opening mechanism 19 and the spring pivot mechanism. As shown in FIG. 2, the lock mechanism 16 has a swing rod 17 that is swingably fixed to the frame of the outer lid 15, and is engaged with the locking member 8 of the main body 2 at one end of the swing rod 17. A locking claw 17a to be stopped and a release button 17b for releasing the locking claw 17a are provided at the other end.

  As shown in FIG. 3, the pressure valve opening mechanism 19 is attached to a cylinder 20 around which an electromagnetic coil is wound, a plunger 21 that moves a metal ball 14 by excitation of the electromagnetic coil, and a tip of the plunger 21. A spring body and an operating rod 22 are included. The spring body is an extension coil spring. The operating rod 22 is supported by a sealing member 23 having elasticity.

  The pressure valve 13 is actuated by the pressure valve opening mechanism 19. In the pressure valve, as shown in FIG. 2, the plunger 21 protrudes and pushes the metal ball 14 by the extension of the spring body to open the valve hole 131. When the electromagnetic coil is excited on the basis of a command from the control device 30 (see FIG. 4), the plunger 21 is pulled into the cylinder 20 against the extension force of the spring body, and so far, the operating rod 22 is made of metal. The pushing force that pushed the ball 14 is lost, the metal ball 14 moves sideways due to the inclination of the valve seat 13a, and the valve hole 131 is closed by the weight of the ball itself. Further, in this closed state, when the excitation to the electromagnetic coil is stopped, the plunger 21 protrudes again by the extension force of the spring body and pushes the metal ball 14 to open the valve hole 131. In addition, a steam sensor Sen <b> 2 for detecting the steam temperature is attached to the upper part of the pressure valve 13.

  As shown in FIG. 2, the reservoir tank 24 includes a discharge cylinder 24a that discharges steam discharged through the pressure valve 13, an empty chamber 24b that temporarily stores a flavor of umami components, and steam that is externally supplied. A steam return valve V2 is provided at the bottom of the empty chamber 24b to return the stored powder into the pot 10. When the steam is ejected from the pressure valve 13, the rice balls that are umami components are led out from the pot 10 together with the steam through the pressure valve 13, and enter the empty space 24 b of the rice tank 24. Temporarily stored. When the amount of rice stored in the empty chamber 24b reaches a predetermined amount, the rice return valve V2 is opened and returned to the inside of the pan 10. In this container storage tank 24, the discharge cylinder 24 a of the container storage tank 24 is press-fitted and fixed into the mounting hole 15 a provided in the recess 24 ′ of the outer lid 15.

  The control device will be described with reference to FIG. FIG. 4 is a block diagram of the control device.

  As shown in FIG. 4, the control device 30 includes a CPU that performs various arithmetic processes, a storage unit that includes a ROM and a RAM that store various data, a rice cooking menu detection circuit that detects a selected rice cooking menu, and a pressure valve 13. A valve opening / closing timer for setting the opening / closing time of the pressure, a counter for counting the number of times the pressure valve 13 is opened / closed, a heating control circuit for controlling the heating temperature and heating time in the pan 10, and a display screen displayed on the display panel 5b. And a drive circuit for the pressure valve opening mechanism 19 that controls the opening / closing timing of the pressure valve 13 by driving the pressure valve opening mechanism 19. The storage means stores rice cooking programs corresponding to various rice cooking menus. This rice cooking program is a water absorption process, a start-up heating process, a boiling maintenance process, a steaming process, and a heat retention process after the completion of these rice cooking processes. The heating control circuit is connected to the pot bottom heater H1, the side heater H2, and the lid heater H3, respectively.

  With reference to FIG. 5, FIG. 6, the rice cooking process by this control apparatus is demonstrated. FIG. 5 is a temperature / pressure curve diagram showing changes in the temperature and pressure in the pan in the rice cooking process, and FIG. 6 is a flowchart up to the start-up heating process in the rice cooking process of the white rice / normal rice cooking course.

  The rice cooking process of the white rice / normal rice cooking course, which has been selected as the menu selection, will be described.

(A) Water absorption process When the white rice / normal rice cooking course is selected by the operation of the display operation unit 5, the water absorption process I is executed first. This water absorption process I is performed by setting the pressure valve 13 in the “open” state (S101), starting the power supply to the pot bottom heater H1 (S102), and multiplying the predetermined water absorption temperature θ2 and the predetermined water absorption time t1. The water absorption temperature θ2 is set to a range between a lower limit value θ21 (for example, 54 ° C.) and an upper limit value θ22 (for example, 55 ° C.), and the water absorption time t1 is, for example, 15 minutes. The water absorption temperature θ2 is controlled based on the detection value K1 of the bottom sensor Sen1, and the water absorption time t1 is measured by a water absorption timer (not shown) (S103). In this water absorption step I, a predetermined amount of water is absorbed by the rice in the pot 10.

(B) Start-up heating process When the measured time TK of water absorption exceeds a predetermined water absorption time t1 (S104), the process proceeds to the start-up heating process II (S105). In this start-up heating process, the pressure valve 13 is opened in the previous water absorption process I and is closed, and the pot 10 is turned on all of the pot bottom heater H1, side heater H2, and lid heater H3, that is, full. Heat with power feeding. When the pan 10 is heated by full power feeding, the pan bottom temperature in the pan 10 starts to rise steeply (see the pan bottom temperature in FIG. 5). Due to the rise in the pot bottom temperature, steam is generated in the pot 10, and the steam temperature rises with a slight delay from the pot bottom temperature (see the steam temperature in FIG. 5). Even if steam is generated, there is a slight gap between the pot opening and the sealing member that seals the inner lid. Therefore, the steam leaks from this gap, and the pressure in the pot 10 is Does not rise. Therefore, the pressure valve 13 is maintained in the closed state until a predetermined time after the transition to the start-up heating process II, but the pressure in the pan 10 does not increase. When full power feeding to the pan bottom heater H1 or the like continues, the pan 10 is further heated to increase the pan bottom temperature and the steam temperature. Therefore, the steam temperature is detected by the steam sensor Sen2, and when the detected value K2 detects a predetermined set reference value θ1 (for example, 40 ° C.), the pressure valve opening mechanism 19 is operated to open the pressure valve 13. (S105 to S107), a time for the pressure in the pan 10 to return to substantially atmospheric pressure (that is, about 4 seconds) at least 0.1 atmospheric pressure or more at a stretch to instantaneously change the pressure in the pan Then, the stirring convection of the cooked rice in the pan is caused, closed again, and pressure cooking is resumed. As shown in FIG. 5, the opening of the pressure valve 13 (S105 to S107) is delayed by a predetermined time t21 from the start time of the start-up heating process II. The predetermined time t21 is a delay time for delaying the opening of the pressure valve 13. This delay time t21 corresponds to the amount of cooked rice in the pan 10, and when the amount of cooked rice is small, the rising curve of the steam temperature rises quickly and quickly reaches the set reference value θ1, resulting in a delay time. If the cooking time is shortened and the amount of cooked rice is increased, the rise of the ascending curve is delayed, and the arrival at the set reference value is delayed, resulting in a longer delay time. The inside of the pan 10 changes in a state where the temperature is increased and the pressure is increased. Then, the steam temperature is detected by the steam sensor Sen2, and when the detected value K2 reaches a predetermined set reference value θ3, the process proceeds to the next boiling maintenance process III (S108, S109). This setting reference value θ3 is, for example, 75 ° C. From this process, in the start-up heating step II, the start-up heating time t2 corresponds to the amount of cooked rice, and is short when the amount of cooked rice is small and long when it is large.

(C) Boiling maintenance process When it is detected that the detected steam temperature K2 has reached the set reference value θ3 (for example, 75 degrees) (S109), the process proceeds to the boiling maintenance process III where boiling starts in the pan 10.

  In the boiling maintenance process III, the pressure valve opening mechanism 19 controls the opening of the pressure valve 13 based on a command from the control device 30. In this pressure valve opening control, the pressure valve 13 is opened several times in a predetermined time unit, and the operation in which the pressure in the pan 10 is lowered from 1.2 atmospheres to near atmospheric pressure is performed. A so-called bumping phenomenon is caused to stir the cooked rice. More specifically, when proceeding to the boiling maintenance step III, the pressure in the pan 10 becomes about 1.2 atmospheres, which is equal to or higher than atmospheric pressure, and the cooked rice boils at a saturation temperature corresponding to this pressure. In this state, the valve opening 131 is opened by operating the pressure valve opening mechanism 19 by the control device 30 and moving the metal ball 14. By forcibly opening the valve hole 131, the pressure in the pan 10 is rapidly reduced to near atmospheric pressure. Thus, when the pressure in the pan 10 is lowered from the predetermined boiling pressure (about 1.2 atm) to the vicinity of the atmospheric pressure at once, the inside of the pan 10 is in a severe bumping state. In this bumping state, bubbles are generated in the pan 10 and the rice is stirred by the bubbles. As a result, the rice is heated uniformly and cooked without unevenness. The predetermined time for forcibly opening the valve hole 131 is set to a time (that is, about 4 seconds) such that the pressure in the pan 10 returns to substantially atmospheric pressure by the first forced opening operation of the valve hole 131. By setting the time for forcibly opening the valve hole 131 to the atmospheric pressure in this way, a large stirring energy can be obtained. Further, after the valve hole 131 is forcibly opened for the predetermined time (4 seconds), the pressure valve opening mechanism 19 is operated to close the valve hole 131 again, and it is heated again for a predetermined time, for example, 28 seconds. In addition, this heating time (28 seconds) is time required for the pressure in the pan 10 to recover to the aforementioned predetermined pressure (about 1.2 atmospheres). This time is obtained experimentally in advance. Then, after the heating for 28 seconds, the plunger 21 may be operated again to cause the bumping described above. This forced opening of the pressure valve 13 by the pressure valve opening mechanism 19 is repeated a plurality of times, for example, four times. When the operation of opening the valve hole 131 a plurality of times is finished, the control of the pressure valve opening mechanism 19 is stopped and the valve hole 131 is closed. As the pressure valve 13 is opened, a rice ball is blown out. This rice ball is temporarily stored in the storage tank 24 and returns to the inside of the pan again. By this step, regardless of the amount of cooked rice, rice can be cooked so that the rice is sufficiently stirred in the pan by stirring utilizing the bumping phenomenon.

(D) Steaming process When the pan bottom temperature reaches a predetermined temperature and a set reference value θ5 (for example, 130 ° C.), it is determined that the water in the pan 10 has dried up and the forced dry-up has been completed. Is done. Subsequently, the steaming process IV is started, and the timing of the steaming time is started. When a predetermined steaming time elapses for a predetermined time, for example, 4 minutes, the valve hole 131 of the pressure valve 13 is forcibly opened by the pressure valve opening mechanism 19 and the process proceeds to the additional cooking process. When entering this additional cooking step, the water is reheated by the heating means to evaporate the water adhering to the surface of the rice, and the additional cooking (reheating) time is measured. And when predetermined | prescribed additional cooking time, for example, 3 minutes passes, the heating operation by a heating means will be stopped, it will transfer to a steaming process, and steaming time will be timed. And when steaming time passes for a predetermined time, for example, 6 minutes, rice cooking will be complete | finished, it will transfer to a heat retention process, and a standard rice cooking process will be complete | finished.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. Since the configuration of the main body is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of the second embodiment will be described focusing on a temperature / pressure curve diagram showing changes in the temperature and pressure in the pan in the rice cooking process of FIG. In addition, since the structure of a rice cooking process is the same as Embodiment 1, description except (b) start-up heating process is abbreviate | omitted.

(B) Start-up heating process When the measured time TK of water absorption exceeds a predetermined water absorption time t1 (S104), the process proceeds to the start-up heating process II (S105). In this start-up heating process, the pressure valve 13 is opened in the previous water absorption process I and is closed, and the pot 10 is turned on all of the pot bottom heater H1, side heater H2, and lid heater H3, that is, full. Heat with power feeding. When the pan 10 is heated by full power feeding, the pan bottom temperature in the pan 10 starts to rise steeply (see the pan bottom temperature in FIG. 7). Due to the rise in the pan bottom temperature, steam is generated in the pan 10, and the steam temperature rises with a slight delay from the pan bottom temperature (see the steam temperature in FIG. 7). This steam temperature is delayed in rising when the amount of cooked rice is large. Even if steam is generated, there is a slight gap between the pot opening and the sealing member that seals the inner lid. Therefore, the steam leaks from the gap and the pressure in the pot 10 does not increase. . When full power feeding to the pan bottom heater H1 or the like continues, the pan 10 is further heated and the pan bottom temperature rises. However, when the steam temperature does not rise (for example, 10 minutes), it is determined that the amount of rice cooking is large. Then, full power feeding continues, the steam temperature is detected by the steam sensor Sen2, and when the detected value K2 detects a predetermined set reference value θ1 (for example, 40 ° C.), the pressure valve opening mechanism 19 is operated. The pressure valve 13 is opened (S105 to S107), and the pressure valve is opened at least once.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. Since the configuration of the main body is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of the third embodiment will be described focusing on a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process of FIG. In addition, since the structure of a rice cooking process is the same as the implementation shape 1, description except (b) start-up heating process is abbreviate | omitted.

(B) Start-up heating process When the measured time TK of water absorption exceeds a predetermined water absorption time t1 (S104), the process proceeds to the start-up heating process II (S105). In this start-up heating process, the pressure valve 13 is opened in the previous water absorption process I and is closed, and the pot 10 is turned on all of the pot bottom heater H1, side heater H2, and lid heater H3, that is, full. Heat with power feeding. When the pan 10 is heated by full power feeding, the pan bottom temperature in the pan 10 starts to rise steeply (see the pan bottom temperature in FIG. 8). Due to the rise in the pan bottom temperature, steam is generated in the pan 10, and the steam temperature rises with a slight delay from the pan bottom temperature (see the steam temperature in FIG. 8). Even if steam is generated, there is a slight gap between the pot opening and the sealing member that seals the inner lid. Therefore, the steam leaks from this gap, and the pressure in the pot 10 is Does not rise. When full power feeding to the pan bottom heater H1 or the like continues, the pan 10 is further heated to increase the pan bottom temperature and the steam temperature. When the temperature rises above a predetermined temperature rise value (for example, 3 ° C. rise) in the start-up heating process from the detection of the steam sensor Sen2 at the end of the previous water absorption process, the pressure valve is opened.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. Since the configuration of the main body is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of Embodiment 4 will be described focusing on a temperature / pressure curve diagram showing changes in temperature and pressure in the pan in the rice cooking process of FIG. In addition, since the structure of a rice cooking process is the same as Embodiment 1, description except (b) start-up heating process is abbreviate | omitted.

(B) Start-up heating process When the measured time TK of water absorption exceeds a predetermined water absorption time t1 (S104), the process proceeds to the start-up heating process II (S105). In this start-up heating process, the pressure valve 13 is opened in the previous water absorption process I and is closed, and the pot 10 is turned on all of the pot bottom heater H1, side heater H2, and lid heater H3, that is, full. Heat with power feeding. When the pan 10 is heated by full power feeding, the pan bottom temperature in the pan 10 starts to rise steeply (see the pan bottom temperature in FIG. 9). Due to the rise in the pan bottom temperature, steam is generated in the pan 10, and since there is a slight gap between the opening of the pan and the sealing member that seals the inner lid, this steam leaks from this gap. The pressure in the pan 10 does not increase. This gap is designed so as to be closed when the pressure in the pan rises above a predetermined value. When full power feeding to the pan bottom heater H1 or the like continues, the pan 10 is further heated to increase the pan bottom temperature and the pressure. Therefore, when the pressure sensor (not shown) detects the pressure value and the detected value K2 detects a predetermined set reference value Σ1 (for example, 1.05 atm), the pressure valve is opened.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described. Since the configuration of the main body is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of the fifth embodiment will be described focusing on a temperature / pressure curve diagram showing changes in the temperature and pressure in the pan in the rice cooking process of FIG. In addition, since the structure of a rice cooking process is the same as Embodiment 1, description other than (a) water absorption process and (b) start-up heating process is abbreviate | omitted.

(A) Water absorption process When the white rice / soft rice cooking course is selected by the operation of the display operation unit 5, the water absorption process I is first executed. This water absorption process I is performed by setting the pressure valve 13 in the “open” state (S101), starting the power supply to the pot bottom heater H1 (S102), and multiplying the predetermined water absorption temperature θ2 and the predetermined water absorption time t1. The water absorption temperature θ2 is set to a range between a lower limit value θ21 (for example, 54 ° C.) and an upper limit value θ22 (for example, 55 ° C.), and the water absorption time t1 is softly cooked by immersing moisture to the center of the rice grains as compared with the white rice cooking course. Since it is necessary, it is usually set long, for example, 25 minutes. The water absorption temperature θ2 is controlled based on the detection value K1 of the bottom sensor Sen1, and the water absorption time t1 is measured by a water absorption timer (not shown) (S103). In this water absorption step I, a predetermined amount of water is absorbed by the rice in the pot 10.

(B) Start-up heating process When the measured time TK of water absorption exceeds a predetermined water absorption time t1 (S104), the process proceeds to the start-up heating process II (S105). Compared to the plain rice normal course, it has a long water absorption time, so it is easy to accumulate on the bottom of the crushed rice pan generated during starch and rice washing, and the boiled bubbles generated during the boiling maintenance process are likely to appear in the start-up heating process. It is difficult to penetrate directly from the bottom of the pan, and heat is not transmitted, especially when cooking large-capacity rice. In this start-up heating process, the pressure valve 13 is opened in the previous water absorption process I and is closed, and the pot 10 is turned on all of the pot bottom heater H1, side heater H2, and lid heater H3, that is, full. Heat with power feeding. When the pan 10 is heated by full power feeding, the pan bottom temperature in the pan 10 starts to rise steeply (see the pan bottom temperature in FIG. 10). Due to the rise in the pan bottom temperature, steam is generated in the pan 10, and since there is a slight gap between the opening of the pan and the sealing member that seals the inner lid, this steam leaks from this gap. The pressure in the pan 10 does not increase. When full power feeding to the pan bottom heater H1 or the like continues, the pan 10 is further heated to increase the pan bottom temperature and the steam temperature. Therefore, the steam temperature is detected by the steam sensor Sen2, and when the detected value K2 detects a predetermined set reference value θ1 (for example, 40 ° C.), the pressure valve opening mechanism 19 is operated to open the pressure valve 13. (S105 to S107), the pressure is released, the pressure valve 13 is repeatedly closed and opened again, and the pressure valve is opened a plurality of times.

  As described above, the rice cooker and the rice cooking method according to the present invention can be sufficiently heated in a pressure rice cooker that cooks rice in a pressurized state during the start-up heating process in a series of rice cooking processes. It is useful as a rice cooker having the function of cooking delicious rice with little uneven cooking.

DESCRIPTION OF SYMBOLS 1 Pressure rice cooker 2 Main body 3 Exterior case 4 Inner case 5 Display operation part 10 Pan 11 Lid body 12 Inner lid 13 Pressure valve 15 Outer lid 19 Pressure valve opening mechanism 30 Control apparatus I Water absorption process II Start-up heating process III Boiling maintenance process H1 Pan bottom heater H2 Side heater H3 Lid heater Sen1 Bottom sensor Sen2 Steam sensor

Claims (5)

A pan into which a predetermined amount of cooked rice containing water and rice is charged, an opening for accommodating the pan, and a rice cooker body having heating means for heating the cooked rice in the pan, the pan and the A lid that closes the opening of the rice cooker body, a pressure valve that communicates or shuts off the inside of the pan and the outside air, and controls the heating amount of the heating means and opens the pressure valve by the pressure valve opening mechanism A control means for controlling the heating, a water absorption process for controlling the heating means and the pressure valve opening mechanism to absorb the cooked rice in the pan, a rising heating process for heating up until boiling, and maintaining the boiling state In the pressure-type rice cooker provided with the control apparatus which performs the rice cooking process including the boiling maintenance process to be performed, and the menu setting means which performs the said rice cooking process by setting a rice cooking menu, the said start-up heating process after the said water absorption process completion | finish And the pressure valve Then, the inside of the pan is raised to atmospheric pressure or more to execute the rising heating step, and the control means is configured to perform the above-described heating in the rising heating step during a period when there is sufficient moisture in the cooked rice in the pan. A pressure rice cooker, wherein the pressure valve is opened by a pressure valve opening mechanism to reduce the pressure in the pan during heating at least 0.1 atm. The control means performs the start-up heating step by closing the pressure valve and increasing the pressure in the pan to an atmospheric pressure or higher in the start-up heating step after the water absorption step is completed. The pressure valve is opened by the pressure valve opening mechanism during a period when the cooked rice in the pan has sufficient moisture in the start-up heating step to reduce the pressure in the pan during heating at least once The pressure rice cooker according to claim 1, wherein: The control means, when the detection value of the steam sensor attached to the lid body in the rising heating process becomes a predetermined set reference value, or from the detection value of the steam sensor at the end of the water absorption process, The pressure rice cooker according to claim 1 or 2, wherein the pressure valve is opened when the temperature rises to a predetermined temperature rise set value or more in the rising heating step. The said control means opens the said pressure valve, when the detected value of the pressure sensor attached to the said cover body becomes more than predetermined | prescribed pressure value by the said start-up heating process. 2. The pressure rice cooker according to 2. The pressure according to any one of claims 1 to 4, wherein the control means opens the pressure valve a plurality of times in a menu in which the water absorption process is longer than a standard rice cooking menu by the rice cooking menu setting. Type rice cooker.

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