JP2006325720A - Rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rice cooker capable of cooking tasty and evenly boiled rice regardless of the amount to be cooked. <P>SOLUTION: This rice cooker is provided with a pot for supplying rice to be cooked, a rice cooker body having an opening part for storing the pot and a heating means for heating the rice to be cooked, a lid body closing the opening part, a pressure valve adjusting the pressure inside the pot, a pressure valve opening mechanism opening the pressure valve, a cooking rice amount determination means determining the amount of the rice to be cooked, and a control means controlling the heating means and the pressure valve opening mechanism based on the amount of the cooking rice determined by the cooking rice amount determination means and sequentially executing a series of the rice cooking process. The control means controls the pressure valve opening mechanism according to the amount of the cooking rice determined by the cooking rice amount determination means and changes at least one of the opening time and the number of opening and closing times of the pressure valve in a boiling retaining process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In general, a pressure-type rice cooker is a water-absorbing process in which water is absorbed by rice in a pot, and after the water-absorbing process, the heating means is heated to full power to rapidly heat and raise the temperature, and the pot is pressurized and brought to a boiling state. The rice is cooked through the rising process, the boiling maintaining process in which the rice is kept in the boiling state in the pot pressurized in the rising process, and the steaming process in which the rice is steamed after the boiling maintaining process. ing.

  The feature of this rice cooker is to shorten the rice cooking time by increasing the pressure in the pan during rice cooking, especially before or during boiling, and allowing water to penetrate into the rice grains in a short time by the synergistic effect of heating and pressure. As a result, it is about to cook soft rice.

  In recent rice cookers, an induction heating coil is attached to the outer periphery of the pan, and a rice cooker using the eddy current generated by this coil, a so-called IH rice cooker, has become the mainstream. However, because this rice cooker has a structure that heats the pan itself, the rice near the inner wall of the pan is heated enough, but it is in the upper center from the center of the pan away from the inner wall Rice may be underheated and uneven cooking may occur.

  In addition, the hot plate rice cooker, which uses a different method from the IH rice cooker and closely contacts the bottom of the pan with a hot plate equipped with a commercially available heater, heats the entire pan bottom with the heater. Since the bottom part is heated intensively, cooking unevenness is produced in the pan like the IH rice cooker, and the top surface of the rice when cooked becomes a mountain shape, and the whole may not be cooked uniformly.

  Therefore, in order to overcome the problems of such rice cookers, the present applicant has made various improvements to this type of rice cooker and has filed numerous patent applications for the results thus far (for example, the following patents). References 1 and 2).

  The rice cooker disclosed in the following Patent Document 1 shortens the rice cooking time and makes the cooked state good, a pan containing the rice to be cooked, a heating source for heating the pan, It is equipped with a pressure device that adjusts the pressure, and by this pressure device, the pressure state in the pan is maintained at a predetermined pressure in a series of rice cooking processes of the preheating process, the cooking process, and the boiling process, and water absorption of rice in the preheating process is performed. The water absorption and heat conduction in each process of cooking, boiling and boiling are improved.

Moreover, the rice cooker disclosed by the following patent document 2 is equipped with a control means, and during the boiling maintenance process in which the to-be-cooked rice in the pan reached the boiling temperature by this control means, the pressure valve is opened by a pressure mechanism. By controlling so as to change the pressure in the boiling pot, the rice grains are vigorously stirred by the boiling phenomenon, so-called bumping phenomenon, agitated while dancing, and cooked.
JP-A-6-22710 (FIG. 1, paragraphs [0005] to [0009]) JP 2004-81824 A (FIG. 2, summary)

  According to the rice cooker disclosed in Patent Documents 1 and 2, delicious rice can be cooked without causing uneven cooking. However, after that, as a result of further research and development, it was found that even in the above rice cooker, uneven cooking sometimes occurs depending on the amount of cooked rice. This cooking unevenness occurs particularly when the amount of cooked rice is large.

  Thus, as a result of various studies on methods for solving the above problems, the present inventors have found that the above problems can be solved by changing the rice cooking process according to the amount of rice cooking, and have reached the present invention.

  That is, an object of the present invention is to provide a rice cooker that can cook delicious rice without uneven cooking, regardless of the amount of rice cooked.

In order to achieve the above object, a rice cooker according to claim 1 of the present application heats a pot into which a rice to be cooked is put, an opening in which the pot is accommodated, and a rice to be cooked in the pot. A rice cooker body having heating means, a lid for closing the opening of the body, a pressure valve mounted on the lid for adjusting the pressure in the pan, and a pressure valve opening mechanism for opening the pressure valve; The cooked rice amount determining means for determining the amount of cooked rice in the pan and the cooked rice in the pan by controlling the heating means and the pressure valve opening mechanism by the cooked rice amount determined by the cooked rice amount determining means. In a rice cooker equipped with a water absorption process, a heating and heating process, a boiling maintenance process and a steaming process in order,
The control means controls the pressure valve opening mechanism according to the rice cooking amount determined by the rice cooking amount determination means, and changes at least one of the opening time and the number of opening / closing times of the pressure valve in the boiling maintaining step. And

  Moreover, the invention according to claim 2 of the present application is the rice cooker according to claim 1, wherein the control means is configured to open and open the pressure valve in proportion to the amount of rice cooked determined by the rice cooking amount judgment means. It is characterized in that at least one of the number of times is changed.

  In addition, the invention according to claim 3 of the present application is the rice cooker according to claim 1, wherein the control means sets the internal pressure in the pan from 2 to around atmospheric pressure by opening and closing the pressure valve in the boiling maintaining step. It is characterized by being varied in the range of 0.0 atm.

Further, the invention according to claim 4 of the present application is the rice cooker according to claim 1, wherein the control means determines the opening time and the number of opening and closing times of the pressure valve according to the size of the valve opening area of the pressure valve. At least one of them is changed.

  Moreover, the invention according to claim 5 of the present application is the rice cooker according to claim 4, wherein the control means controls the opening time and the number of opening and closing of the pressure valve in inverse proportion to the valve opening area of the pressure valve. It is characterized by doing.

Moreover, invention of Claim 6 of this application is the rice cooker of Claim 4, The valve-mouth area of the said pressure valve exists in the range of 3-30 mm < ² >.

  In addition, in the invention according to claim 7 of the present application, in the rice cooker according to any one of claims 1 to 6, the opening time of the pressure valve is 1 to 10 seconds, and the number of opening and closing thereof is 1 to 10. It is characterized by 15 times.

  By providing the above-described configuration, the present invention has the following excellent effects. That is, according to invention of Claim 1, according to the rice cooking amount determined by the rice cooking amount determination means, by controlling at least one of the opening time and the number of opening and closing of the pressure valve in the boiling maintenance step, The phenomenon is efficiently generated, and the cooked rice is stirred, so-called dancing, and stirred, so that delicious rice without cooking unevenness can be cooked regardless of the amount of cooking. In particular, when the amount of cooked rice is large, the food to be cooked in the center and the inner wall side of the pan is vigorously stirred, so that the whole is evenly mixed, so there is no uneven cooking. Of course, since the cooked rice is cooked under high temperature and high pressure, moisture and heat penetrate to the core of the rice grain, and the rice is cooked without a core.

  According to invention of Claim 2, according to the size of rice cooking, the to-be-cooked food in a pan can be stirred efficiently and effectively, and delicious rice can be cooked. In particular, even when the amount of cooked rice is large, the cooked rice in the pan is mixed efficiently and effectively, so there is no uneven cooking.

  According to the invention of claim 3, in the boiling maintaining step, the pressure in the pan is set to be 2.0 atm at the maximum when the pressure valve is closed, and close to the atmospheric pressure when it is opened. In proportion to the pressure difference, the bumping phenomenon in the pot becomes intense, and the cooked rice can be stirred safely and efficiently.

  According to the fourth and fifth aspects of the invention, when using a pressure valve with a small valve opening area, a sufficient pressure reduction effect is secured by increasing the opening time of the pressure valve and increasing the number of times of pressure reduction. The entire stirring can be performed efficiently.

  Also, when using a pressure valve with a large valve opening area, the pressure can be reduced at a stretch, so the opening time is short, and the number of times of pressure reduction is reduced because the mixing effect per time is large. Therefore, by selecting at least one of the opening time and the opening / closing frequency of the pressure valve according to the size of the valve opening area, the cooked rice in the pan can be uniformly stirred.

According to the invention of claim 6, by setting the valve port area of the pressure valve in the range of 3 to 30 mm ² , the design of the pressure valve mechanism can be facilitated, and the pressure adjustment in the pan can be performed safely and smoothly. it can. If this area is increased, the pressure in the pan can be quickly released at once. However, if the area is increased, not only is this dangerous, but moisture is also quickly removed, so this range is preferable.

  According to the seventh aspect of the present invention, the number of times the pressure valve is opened and closed increases if the remaining water in the pan is sufficient. The range of 1-15 times is good for obtaining. The opening time is 1 to 10 seconds, which is a preferable time for sufficiently generating a pressure difference in the pan during opening and closing.

  Hereinafter, the best embodiment 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. Other embodiments within the scope are equally applicable.

  1 is a sectional view of a rice cooker according to one embodiment of the present invention, FIG. 2 is an enlarged sectional view showing a pressure valve opening mechanism of FIG. 1, FIG. 3 is a block diagram showing an internal configuration of a control means, and FIGS. 6 is a control flowchart of the rice cooker, FIG. 7 is an explanatory diagram showing the pressure in the pot, the temperature at the bottom of the pot, the steam temperature, the opening and closing timing of the pressure valve, and the heating timing of the heating means in each process from the start of rice cooking to the heat retention of the rice cooker. FIG. 8 is a diagram showing the valve opening time and the number of valve opening / closing times with respect to the amount of cooked rice.

  The rice cooker of the present invention has a plurality of rice cooking courses depending on the type of rice and the state of cooking, for example, “white rice / normal”, “white rice / sushimeshi”, and “brown rice / normal”. In addition to this basic rice cooking course, it also has other courses such as “white rice / high speed”, “white rice / application”, and “rice porridge”. In the present embodiment, a “rice cooked rice / normal” rice cooking course that is most frequently used among these rice cooking courses will be described.

  First, the structure of the rice cooker will be described.

  1 and 2, (1) is a rice cooker body, (2) is a pan made of aluminum and stainless clad material for containing water and rice, (3) is a case for storing a pan (2), (4 ) Is a heating means attached to the outer wall and the outer bottom wall of the case (3). For example, an induction coil is used as the heating means (4).

  (5) is an openable / closable lid that covers the opening (6) of the pan (2), and comprises a removable inner lid (7) provided on the lower side and an outer lid (8) provided on the upper side. Is done.

  As shown in FIG. 2, the inner lid (7) is provided with a pressure valve (14), and a valve seat (10) having a valve port (9), and a valve on the valve seat (10) by its own weight. A pressure valve opening mechanism (18) including a metal ball (11) for closing the mouth (9) and a cover (12) covering the ball (11) is provided. The pressure valve (14) moves or leaves the ball (11) on the valve port (9) depending on the balance between the pressure in the pan (2) and the weight of the ball (11). ) Moves the valve opening (9).

  Moreover, when the inside of the pan (2) is abnormally pressurized to the inner lid (7), for example, when the pressure valve (14) fails to open during cooking, the pressure in the pan is opened. A safety valve (9a) for escaping is provided (see FIG. 1).

  As shown in FIGS. 1 and 2, a plunger (17) is attached to the pressure valve (14) in the outer lid (8), and this plunger (17) is controlled by the control means (20). The That is, when the plunger (17) does not receive the output from the control means (20), the rod (17a) protrudes from the cylinder (17b) and the ball (11) on the valve port (9) is moved to the valve port ( 9) Push in the lateral direction to forcibly open the valve port (9). When the plunger (17) receives the output of the control means (20), the rod (17a) is drawn into the cylinder (17b). At this time, the ball (11) returns to the valve port (9) by its own weight and closes the valve port (9).

  In this way, the plunger (17) operates as a pressure valve opening mechanism, and this opening operation forcibly reduces the pressure in the pan that has been pressurized during the rice cooking process.

  The outer lid (8) has a steam port (15) through which the inside of the pan (2) communicates with the atmosphere via the valve port (9), and the pressure and steam in the pan (2) are released into the atmosphere. ing.

  As shown in FIG. 1, the rice cooker body (1) includes selection means (16) for selecting the above-described rice cooking course.

  As is well known, the control means (20) is composed of hardware composed of a CPU (22), a ROM (23), a RAM (24), etc., and software for executing the contents of the flowchart described later. The

  At the bottom of the pan (2), as shown in FIG. 1, a temperature sensor (19b) for detecting the pan bottom temperature that also functions as rice cooking amount detection means, and a lid (8) at an appropriate position. A steam sensor (19a) serving as a boiling detection means for detecting the steam temperature is attached, and the outputs of the sensors (19a) and (19b) are sent to the control means (20). In addition, since it is already well-known to detect the amount of rice cooking in a pan by the output of a temperature sensor, detailed description is abbreviate | omitted.

  As shown in FIGS. 1 and 2, a filter (21) that is detachably attached to the valve seat (10) and has a plurality of small holes is attached to the lower portion of the pressure valve (14). By attaching this filter (21), it is possible to prevent the rice grains flowing in the pan at a time when the pressure valve (14) is opened from being blocked by the filter (21) and released to the outside air.

  Next, the internal configuration of the control means (20) will be described with reference to FIG.

(22) is a CPU for performing various arithmetic processes in the control means (20), and (23) and (24) are ROM and RAM for storing the rice cooking process in the rice cooker (1). (25) is a depressurization timer for measuring the valve opening time in the boiling maintenance process in the rice cooking process, and (26) is preset such as the water absorption process time and the valve closing time after the valve opening in the boiling maintenance process. (27) is a rice cooking amount detection means for detecting the amount of cooked rice put into the pan (2) from the output of the temperature sensor (19b), (27) 28) is a heating control means for controlling the heating means (4) according to the rice cooking process, (29) is a counter for counting the number of times of opening and closing the valve in the boiling maintenance process, and (30) is a counter (29 ) A counter upper limit value setting means for setting an upper limit of the valve number being und, (31) is a pressure valve opening mechanism control means for controlling the pressure valve opening mechanism (18).

  The valve opening time of the decompression timer (25) and the valve opening / closing frequency of the counter upper limit value setting means (30) are changed according to the amount of rice cooked, and the change is made by the CPU (22) by the ROM ( 23) or using a rice cooking amount sorting table stored in the RAM (24). Moreover, about this distribution table, although the following description is given as what distributes in three steps, ie, the amount of rice cooking "Large", the amount of rice cooking "Medium", and the amount of rice cooking "Small" in this embodiment, There may be two stages or multi-stages of three or more stages.

  Next, the rice cooking process by the rice cooker of this invention is demonstrated mainly with reference to FIGS. In addition, although a present Example demonstrates the case where the "white rice and normal" course is selected in a rice cooking course, the following series of rice cooking processes respond | corresponds to the figure shown in FIG.

  First, at the start of rice cooking, the pan (2) into which a predetermined amount of water and white rice has been charged by the user is housed in the inner case (3), and the lid (5) is closed (S1). Next, the rice cooking course is selected by the selection means (16). When white rice / normal course is selected (S2), the heating control means (28) applies a high frequency current to the heating means (4) attached to the outer bottom wall and the outer wall of the inner case (3). Then, an eddy current is generated in the pan (2), the pan is heated, and heating of the cooked rice is started (S3).

  Next, the pressure release mechanism control means (31) of the control means (20) operates the pressure valve release mechanism (18) to move the ball (11), and the pressure valve (14) is forcibly opened ( S4), a water absorption step is executed (S5). When this water absorption process is started, the timer (26) starts measuring the water absorption time, and then the pan bottom temperature K1 is measured by the temperature sensor (19a) (S6). The measurement of the pan bottom temperature K1 is performed until a predetermined temperature is reached. When it is confirmed that the pan bottom temperature has reached a predetermined value, for example, 55 ° C. (S7), the heating amount of the heating means (4) is controlled by the control means (20). The water absorption time is measured while controlling the temperature to keep the cooked rice at a predetermined temperature (S8). This water absorption step is continued for a preset water absorption time, for example, 15 minutes (see FIG. 7).

  When the set water absorption time (15 minutes) elapses (S9), the process proceeds to the rising process (S10). In this rising process, the heating means (4) is fully heated (full power heating) so as to be in a boiling state in a short time (S10), and in this rising process, the temperature sensor (19b) uses the pan (2). The rice cooking amount is detected by the rice cooking amount detection means (27) by measuring the temperature inside (S11). Further, the amount of cooked rice detected here is temporarily stored in the ROM (23) or RAM (24) (S12). In this rising step, full power heating is performed, and the pressure release mechanism control means (31) operates the pressure valve release mechanism (18) to pull back the rod (17a) of the plunger (17), The pressure valve (14) is closed by 11) (S13). That is, the ball (11) rolls onto the valve port (9) by its own weight, closes the valve port (9), and closes the pressure valve (14). In this state, the pressure in the pan (2) is increased until the pressure rises to a pressure value capable of pushing up the ball (11) through the valve port (9). Therefore, the pressure of the steam in the pan at this time can be appropriately determined by setting the weight of the ball (11) and the size of the valve port (9).

  In this start-up process, the steam temperature K2 is measured by the steam sensor (19a) (S14). And when this steam temperature K2 reaches predetermined temperature, for example, 75 degreeC (S15), it will become the temperature which a to-be-cooked rice causes a boiling phenomenon, and a starting process is complete | finished. The pressure in the pan (2) at this time is controlled by the pressure valve (14) and is a predetermined pressure equal to or higher than the atmospheric pressure, for example, about 1.2 atm. In the subsequent boiling maintaining step, the heating means is used. (4) is always in the operating state.

  Before proceeding to the next boiling maintenance step, as shown in FIG. 5, the decompression timer (25) and the upper limit value of the counter are set. The depressurization timer (25) is set based on the amount of cooked rice detected in (S16) and (S11), and the time keeping distribution table for the predetermined depressurization timer (25) stored in the ROM (23) or RAM (24). It is done using. This sorting table is based on a table as shown in FIG. 8. For example, when the amount of cooked rice is “large”, the valve opening time, that is, the time measured by the decompression timer (25) is ta, and the amount of cooked rice is “medium”. In this case, the valve opening time is tb, and when the amount of cooked rice is “small”, the valve opening time is tc. Each valve opening time is ta> tb> tc.

  Similarly, the upper limit of the counter set in the counter upper limit setting means (30) is also performed by a sorting table based on the table shown in FIG. 8 (S17). For example, when the amount of rice cooking is “large”, the upper limit value of the counter, That is, the valve opening / closing frequency is Ea, the upper limit value of the counter is Eb when the amount of rice cooking is “medium”, and the upper limit value of the counter is Ec when the amount of rice cooking is “small”. The upper limit value of each counter is Ea> Eb> Ec.

  In addition, as described above, in the present embodiment, what changes both the valve opening time and the valve opening / closing frequency in proportion to the amount of rice cooking will be described, but the valve opening time and the valve opening / closing frequency are changed more finely according to the rice cooking amount. It is also possible. That is, in this embodiment, the amount of cooked rice is divided into three stages of “large”, “medium”, and “small”, and the valve opening time and the number of times of opening and closing the valve are also changed in three stages according to the amount of cooked rice. In addition, only one of the valve opening time and the valve opening / closing time may be changed according to the number of cups of rice cooking, and if this is done, rice cooking is performed by controlling the valve opening time and valve opening / closing time more finely. Optimum rice cooking control can be performed according to the amount, so that rice can be cooked more efficiently.

  When the above setting is completed, the process proceeds to the boiling maintenance process (S18). When the process proceeds to the boiling maintenance process, the pressure in the pan (2) becomes a predetermined pressure equal to or higher than atmospheric pressure, for example, about 1.2 atm. Boils at the saturation temperature corresponding to the pressure.

  Moreover, if it enters into a boiling maintenance process, first, it will distribute with reference to the rice cooking amount detected by (S11) so that control according to each rice cooking amount may be performed (S19). For example, when the amount of rice cooking is “medium”, the pressure valve opening mechanism (18) is operated by the pressure release mechanism control means (31) of the control means (20) to move the ball (11), thereby moving the pressure valve. The forced opening operation of (14) is performed (S20). By the forced opening operation of the pressure valve (14), the pressure in the pressurized state in the pan (2) is reduced to near atmospheric pressure.

  Thus, in the boiling maintaining step, when the pressure in the pan (2) is lowered from the predetermined boiling pressure (about 1.2 atm) to near atmospheric pressure at once, the inside of the pan (2) is in a severe bumping state. In this bumping state, bubbles are generated in the pan, and the cooked rice is stirred by the bubbles. As a result, the cooked rice is heated uniformly and cooked.

  When this forcible opening operation is performed, the time of the decompression timer (25) is started simultaneously (S21). The opening time of the pressure valve (14) is tb because the amount of rice cooking is “medium”. Further, when the pressure valve 13 is forcibly opened for the time tb (S22), the pressure valve opening mechanism (18) is operated to close the pressure valve (13) again (S23). Heat again for a predetermined time (S24). This heating time is a time required for the pressure in the pan (2) to recover to the above-mentioned predetermined pressure (about 1.2 atm), and this time is measured by the timer (26). This time is obtained experimentally in advance.

  The forced opening of the pressure valve (14) by the pressure valve opening mechanism (18) is performed a predetermined number of times, that is, Eb times when the amount of rice cooking is “medium” (S26). In addition, if time passes in a boiling maintenance process, the amount of residual water in a pan (2) will reduce, a pressure fluctuation range will become small, and a bumping phenomenon will become weak. For this reason, the forced opening of the pressure valve (14) is effective when concentrated in the initial stage of the boiling maintenance process.

  When the operation of opening the pressure valve (14) Eb times is finished, the forced opening of the pressure valve (14) by the pressure valve opening mechanism (18) is stopped, the pressure valve (14) is closed, and the bottom temperature of the pan K3 is measured (S27). When the pan bottom temperature K3 reaches a predetermined temperature, for example, 130 ° C. (S28), it is determined that the water in the pan (2) has dried up and the forced dry-up has been completed, so the heating action by the heating means (4) is stopped. (S29), the process proceeds to the steaming step.

  If it is determined in S19 that the amount of rice cooking is “large”, the pressure release mechanism control means (31) of the control means (20) operates the pressure valve release mechanism (18) to move the ball (11). By moving, the forced opening operation of the pressure valve (14) is performed (S30). By the forced opening operation of the pressure valve (14), the pressure in the pressurized state in the pan (2) is reduced to near atmospheric pressure. That is, the inside of the pan (2) is brought into a bumping state by reducing the pressure in the pan (2) from a predetermined boiling pressure (about 1.2 atm) to near atmospheric pressure at once.

When this forcible opening operation is performed, the depressurization timer (25) starts counting at the same time (S31). The opening time of the pressure valve (14) is ta because the amount of cooked rice is “large”. Further, when the pressure valve 13 is forcibly opened for the time ta (S32), the pressure valve opening mechanism (18) is operated to close the pressure valve (13) again (S33), which is set in advance. Heat again for a predetermined time (S34). This heating time is the time required for the pressure in the pan (2) to recover to the aforementioned predetermined pressure (about 1.2 atmospheres), and this time is measured by the timer (26). Also, this time is determined in advance by experiments.

  The forcible opening of the pressure valve (14) by the pressure valve opening mechanism (18) is performed a predetermined number of times, that is, Ea times when the amount of cooked rice is “large” (S26). In addition, if time passes in a boiling maintenance process, the amount of residual water in a pan (2) will reduce, a pressure fluctuation range will become small, and a bumping phenomenon will become weak. For this reason, the forced opening of the pressure valve (14) is effective when concentrated in the initial stage of the boiling maintenance process.

  When the operation of opening the pressure valve (14) Ea times is finished, the same processing as in the case of the rice cooking amount “medium” is performed, and thus the description is omitted here.

  Furthermore, when it is determined in S19 that the amount of cooked rice is “small”, the pressure release mechanism control means (31) of the control means (20) operates the pressure valve release mechanism (18) to cause the ball (11). Is moved to forcibly open the pressure valve (14) (S37). By the forced opening operation of the pressure valve (14), the pressure in the pressurized state in the pan (2) is reduced to near atmospheric pressure. That is, the inside of the pan (2) is brought into a bumping state by reducing the pressure in the pan (2) from a predetermined boiling pressure (about 1.2 atm) to near atmospheric pressure at once.

When this forcible opening operation is performed, the time of the decompression timer (25) is started simultaneously (S38). The opening time of the pressure valve (14) is tc because the amount of cooked rice is “small”. When the forcible opening of the pressure valve 13 is performed for the time tc (S39), the pressure valve opening mechanism (18) is operated to close the pressure valve (13) again (S40), which is set in advance. Heat again for a predetermined time (S41). This heating time is the time required for the pressure in the pan (2) to recover to the aforementioned predetermined pressure (about 1.2 atmospheres), and this time is measured by the timer (26). Also, this time is determined in advance by experiments.

  The forced opening of the pressure valve (14) by the pressure valve opening mechanism (18) is performed a predetermined number of times, that is, Ec times when the amount of cooking rice is “small” (S43). In addition, if time passes in a boiling maintenance process, the amount of residual water in a pan (2) will reduce, a pressure fluctuation range will become small, and a bumping phenomenon will become weak. For this reason, the forced opening of the pressure valve (14) is effective when concentrated in the initial stage of the boiling maintenance process.

  When the operation of opening the pressure valve (14) is completed Ec times, the same processing as in the case of the rice cooking amount “medium” is performed, and thus the description thereof is omitted here.

  Next, the steaming process will be described with reference to FIG. When the boiling maintenance process is completed and the process proceeds to the steaming process, the process first proceeds to the steaming process 1 and starts measuring the steaming time T2 (S44). When the predetermined steaming time T2 elapses for a predetermined time, for example, 4 minutes (S45), the pressure valve (14) is forcibly opened by the pressure valve opening mechanism (18) (S46), and the process proceeds to the additional cooking step. If it enters into this additional cooking process, while reheating by a heating means (4) and evaporating the water adhering to the surface of rice, the additional cooking (reheating) time T3 is measured (S47). And when predetermined | prescribed additional cooking time T3, for example, 3 minutes, (S48) passes, the heating operation by a heating means (4) will be stopped, it will transfer to the steaming process 2, and the steaming time T4 will be timed (S49). When the steaming time T4 elapses for a predetermined time, for example, 6 minutes (S50), the rice cooking is finished (S51), the process proceeds to the heat retaining process (S52), and the rice cooking process in the “white rice / normal” course is finished.

Although no mention is made of the size of the 8 valve port (9), when the opening area of the valve port (9) is 3 to 30 mm ^2, especially 12 mm ² (valve port (9) is cylindrical, the diameter About 3.6 mm) and around this value are preferred. In addition, if the area of the valve port (9) is increased, the pressure can be quickly released quickly, and the pressure reducing timer (25) can be measured in a short time, and a sudden pressure change occurs in the pan (2). Therefore, since more efficient stirring can be performed, the time measured by the pressure reducing timer (25) (valve opening time) and the upper limit value of the counter (number of valve opening / closing times) are set to the size of the valve port (9). It is preferable to change in inverse proportion.

  Furthermore, the opening / closing frequency of the pressure valve (14) is preferably 1 to 15 times. If the remaining water in the pan is sufficient, the effect of stirring increases as the number of times increases. However, the amount of residual water decreases, so that it is preferable that the number of times is within the range to obtain sufficient stirring. When the pressure valve is opened and closed once or twice, a sufficient stirring effect cannot be obtained. Furthermore, although the opening time is set to 1 to 10 seconds, this is a preferable time for causing a sufficient pressure difference in the pan during opening and closing.

  As described above, the present invention executes the heat retaining process through the boiling maintaining process and the steaming process for maintaining the inside of the pan at a constant pressure after the start-up process for rapidly heating the cooked rice. By opening the pressure valve during the process, the pressure inside the pan is drastically lowered to stir the rice grains, and the rice grains in the center of the pan and the rice grains in the inner wall are mixed and the whole rice grains in the pan Can be heated uniformly and can be cooked evenly.

  In particular, when rice is cooked in this way, a hole of a predetermined size, a so-called crab hole, is formed on the top surface of the cooked rice to be cooked, which is visually delicious. Become.

  Also, by controlling the opening time and the number of opening and closing of the pressure valve in the boiling maintenance process according to the rice cooking amount determined by the rice cooking amount determination means, the rice cooking process can be varied according to the size of the rice cooking amount, thereby making the cooking unevenness You can cook delicious rice with no flavor. In particular, when the amount of cooked rice is large, by increasing the opening time and the number of times of opening and closing the pressure valve, the rice to be cooked in the center and on the inner wall side can be vigorously stirred several times, and this can be evenly mixed. Because it is mixed, there is no uneven cooking. In addition, since the cooked rice is cooked under high temperature and high pressure, moisture and heat penetrate into the core of the rice grain, and the rice is cooked without a core.

  In this embodiment, the internal pressure in the pressurized state in the pan is set to 1.2 atm. However, the internal pressure may be increased to about 2.0 atm. Thereby, the pressure difference in the pan accompanying the pressure valve opening / closing control in the boiling maintenance step becomes larger, the bumping phenomenon in the pan becomes intense, and the cooked rice can be cooked more uniformly and efficiently.

  In this embodiment, an induction coil is used as the heating means (4). However, the heating means (4) is not limited to such a heating means, and a heating plate equipped with a heater is attached to the bottom of the pan or other heating method. There may be. Further, the pressure valve opening / closing mechanism may be a mechanically acting mechanism or an electromagnetically acting mechanism as long as the pressure valve can be forcibly opened from the closed state. .

Sectional drawing of the rice cooker which concerns on one Example of this invention, The expanded sectional view which shows the pressure valve opening mechanism of FIG. Block diagram showing the internal configuration of the control means; Control flow chart of rice cooker, Control flow chart of rice cooker, Control flow chart of rice cooker, Explanatory drawing showing the pressure in the pan in each step from the start of rice cooking to the heat insulation of the rice cooker, the pan bottom temperature, the steam temperature, the opening / closing timing of the pressure valve, the heating timing of the heating means, FIG. 8 is a diagram showing the valve opening time and the number of valve opening / closing times relative to the amount of cooked rice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rice cooker body 2 Pan 4 Heating means 9 Valve port 11 Ball 14 Pressure valve 16 Selection means 18 Pressure valve opening mechanism 19a Temperature sensor 19b Steam sensor 20 Control means 22 CPU
23 ROM
24 RAM
25 Depressurization timer 26 Timer 27 Rice cooking amount detection means 28 Heating control means 29 Counter 30 Counter upper limit value setting means 31 Pressure valve opening mechanism control means

Claims (7)

A pan into which the rice to be cooked is charged, an opening in which the pan is accommodated, and a rice cooker body having heating means for heating the cooked rice in the pan, a lid for closing the opening of the body, A pressure valve that is attached to the lid to adjust the pressure in the pan, a pressure valve opening mechanism that opens the pressure valve, a rice cooking amount determination unit that determines the amount of rice to be cooked in the pan, and the rice cooking Control means for controlling the heating means and the pressure valve opening mechanism according to the amount of cooked rice determined by the quantity judging means to sequentially execute the water absorption process, the heating and heating process, the boiling maintaining process and the steaming process of the cooked food in the pan. In a rice cooker equipped with
The control means controls the pressure valve opening mechanism according to the rice cooking amount determined by the rice cooking amount determination means, and changes at least one of the opening time and the number of opening / closing times of the pressure valve in the boiling maintaining step. Rice cooker.   2. The rice cooker according to claim 1, wherein the control unit changes at least one of an opening time and an opening / closing frequency of the pressure valve in proportion to a rice cooking amount determined by the rice cooking amount determination unit.   2. The rice cooker according to claim 1, wherein the control means varies the internal pressure in the pan in the range from the vicinity of atmospheric pressure to 2.0 atm by opening and closing the pressure valve in the boiling maintaining step.   2. The rice cooker according to claim 1, wherein the control unit changes at least one of an opening time and an opening / closing frequency of the pressure valve according to a size of a valve opening area of the pressure valve.   5. The rice cooker according to claim 4, wherein the control means controls the opening time and the number of times of opening and closing the pressure valve in inverse proportion to the valve port area of the pressure valve. Valve area of the pressure valve, rice cooker according to claim 4, characterized in that in the range of 3 to 30 mm ^2.   The rice cooker according to any one of claims 1 to 6, wherein the pressure valve is opened for 1 to 10 seconds and opened and closed 1 to 15 times.

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