JP2011183082A - Rice cooker - Google Patents

Abstract

The present invention provides a rice cooker that can improve the taste of rice and shorten the cooking time.
[Solution] A pot in which rice and water are put, a pot heating apparatus for heating the pot, a pot temperature detecting section for detecting the temperature of the pot, and turning on / off the pot heating apparatus based on the detected temperature of the pot temperature detecting section. And a rice cooking control unit that performs the rice cooking process, and the rice cooking control unit turns on the pot heating device when the temperature detected by the pot temperature detection unit is equal to or higher than the first reference temperature when the pot heating device is on. When the pot heating device is off, the pot heating device is switched from off to on when the temperature detected by the pan temperature detecting unit is lower than the second reference temperature, which is higher than the first reference temperature. .
[Selection] Figure 2

Description

  The present invention relates to a rice cooker mainly used for home use.

  In recent years, in this type of rice cooker, good taste of rice is required, and shortening of the rice cooking time is required. The taste of rice is greatly influenced by the water absorption state of rice in the rice cooking process. That is, if the water absorption of the rice is not sufficient, the rice remains with a core that is generally considered not to taste good. For this reason, in order to improve the taste of rice, it is important that the rice has sufficient water absorption.

  Conventionally, various rice cookers intended to promote water absorption of rice have been proposed. For example, Patent Document 1 (Japanese Patent Laid-Open No. 10-113278) includes a first heating coil that heats the bottom surface portion of the pan and a second heating coil that heats the bottom side surface portion of the pan, and these heating coils. A rice cooker in which each is energized independently is disclosed. In this rice cooker, by energizing each of the first heating coil and the second heating coil independently, a temperature difference is generated between the portion heated by the first heating coil and the portion heated by the second heating coil. And a strong convection is generated in the pan due to the temperature difference. Thereby, the unevenness of heating is reduced and the taste of rice is improved.

  Moreover, FIG. 6 is a figure which shows the temperature change of a pan (cooking object), the drive timing of a pan heating apparatus, and required time when a rice cooking process is implemented using the conventional common rice cooker. Here, the “rice cooking step” is mainly composed of four steps of a preheating step (also referred to as a water absorption step), a temperature raising step, a boiling maintenance step, and a steaming step. The preheating step is a step of immersing the rice in water having a temperature lower than the gelatinization temperature (about 60 ° C.) of the rice to cause the rice to absorb water in advance. The temperature raising step is a step of raising the temperature of the water in the pan to a boiling state (about 100 ° C.). A boiling maintenance process is a process of maintaining the boiling state of the water in a pan, gelatinizing rice starch, and raising the gelatinization degree to about 50% to 60%. Here, “gelatinization” refers to a state in which starch in rice is swollen and softened by absorbing water and further applying heat. The steaming process is a process of evaporating excess water using residual heat and raising the degree of gelatinization of rice to nearly 100%.

  As shown in FIG. 6, in the conventional general rice cooker, especially in a preheating process, on-off of the pan heating apparatus is controlled so that the temperature of the pan changes with a large amplitude. More specifically, with respect to one reference temperature (for example, 60 ° C.), the pan heating device is turned off when the pan temperature is high, and the pan heating device is turned on when the pan temperature is low. I am doing so. Thereby, the temperature change of a pan is enlarged, the strong convection is generated in a pan, the unevenness of heating is reduced, and the taste of rice is improved.

  Moreover, conventionally, the process which has a big influence on the taste of rice among the said rice cooking processes is considered to be a preheating process. The higher the moisture content of rice at the end of this preheating step, the more water absorption can be promoted into the rice grains in the later step, and the taste of rice can be improved. On the other hand, when the moisture content of the rice cannot be raised to a certain level (for example, 30% or more) in the preheating process, when the rice is gelatinized in the subsequent process, only the surface layer portion of the rice grains It will be gelatinized. As a result, the surface layer portion impedes water absorption into the center of the rice grain, and the taste of rice becomes poor. For this reason, the improvement of the moisture content of rice is generally performed by using more than half of the rice cooking time as the time for the preheating step.

JP-A-10-113278

  However, if the time for the preheating process is lengthened, the cooking time will naturally increase. In particular, the time of the preheating step has a large influence on the rice cooking time because the ratio of the preheating step to the rice cooking time is high. Conversely, it can be said that it is most effective to shorten the time of the preheating process from the viewpoint of shortening the cooking time. Rice has the property that the higher the water temperature, the faster the water absorption rate. For this reason, as shown in FIG. 6, in a preheating process, it is effective for shortening rice cooking time to heat a pan so that the temperature of a pan may become the gelatinization temperature of rice.

  However, as described with reference to FIG. 6, in the conventional general rice cooker, the amplitude of the temperature change of the pan is increased in order to generate strong convection in the pan. For this reason, in the preheating process, the period during which the temperature of the pan is equal to or higher than the gelatinization temperature of rice is long. In particular, until the pot temperature reaches the gelatinization temperature of the rice for the first time, the pot temperature rapidly rises with the heating power of the pot heating device as high heating power. The temperature can be, for example, 10 ° C. higher than the gelatinization temperature of rice. When the temperature of the pot 101 reaches the gelatinization temperature of rice in the preheating step, as shown in FIG. 7, the starchy substance having adhesiveness is eluted from the rice grains R1 located along the inner surface of the pot 101, and the adjacent rice grains R1. , R1 easily adhere to each other. Thereby, when the layer which rice grains R1 and R1 adhered to each other along the inner surface of the pan 101 is formed, the heat transfer to the rice grain R2 located away from the inner surface of the pan 101 becomes worse, and the inside of the pan The generation of strong convection is hindered. As a result, the water absorption of the rice grain R2 is deteriorated, the moisture content of the whole rice is lowered, and the taste of rice is deteriorated. In order to avoid this problem, lowering the temperature of the pan as a whole leads to an increase in cooking time.

  Accordingly, an object of the present invention is to provide a rice cooker that can solve the above-described problems and can further improve the taste of rice and shorten the cooking time.

In order to achieve the above object, the present invention is configured as follows.
According to the first aspect of the present invention, a pan into which rice and water are placed;
A pot heating device for heating the pot;
A pan temperature detector for detecting the temperature of the pan;
A rice cooking control unit that controls on / off of the pan heating device based on the detected temperature of the pan temperature detection unit, and performs a rice cooking process including a preheating process, a temperature rising process, a boiling maintenance process, and a steaming process,
With
The rice cooking control unit
When the pan heating device is on, when the temperature detected by the pan temperature detection unit is equal to or higher than the first reference temperature, the pan heating device is switched from on to off,
When the pan heating device is off, the pan heating device is switched from off to on when the detected temperature of the pan temperature detecting unit is equal to or lower than a second reference temperature that is higher than the first reference temperature. ,
Provide rice cooker.

According to the 2nd aspect of this invention, the said rice cooking control part in the said preheating process,
When the temperature detected by the pan temperature detection unit is equal to or higher than the first reference temperature when the pan heating device is on, the pan heating device is switched from on to off, and when the pan heating device is off When the detected temperature of the pan temperature detection unit is equal to or lower than the second reference temperature, the pan heating device is switched from off to on.
A rice cooker according to the first aspect is provided.

  According to a third aspect of the present invention, there is provided the rice cooker according to the first aspect, wherein the second reference temperature is a gelatinization temperature of rice.

  According to the 4th aspect of this invention, when the said rice cooking control part reaches | attains the 3rd temperature lower than the said 1st reference temperature initially after the detection temperature of the said pan temperature detection part starts the said preheating process. The rice cooker as described in any one of the 1st-3rd aspect which weakens the thermal power at the time of ON of the said pan heating apparatus is provided.

According to a fifth aspect of the present invention, a pan into which rice and water are placed;
A pot heating device for heating the pot;
A pan temperature detector for detecting the temperature of the pan;
A rice cooking control unit that controls on / off of the pan heating device based on the detected temperature of the pan temperature detection unit, and performs a rice cooking process including a preheating process, a temperature rising process, a boiling maintenance process, and a steaming process,
With
The rice cooking control unit
After the detection temperature of the pan temperature detection unit first reaches a preset temperature,
After the pan heating device is turned off for a first time such that the detected temperature of the pan temperature detecting unit is lower than the preset temperature, the detected temperature of the pan temperature detecting unit becomes the preset temperature. To turn on the pan heating device for a second time, repeat the temperature control multiple times,
Provide rice cooker.

  According to the 6th aspect of this invention, the said rice cooking control part provides the rice cooker as described in a 5th aspect which performs the said temperature control in the said preheating process.

  According to a seventh aspect of the present invention, there is provided the rice cooker according to the sixth aspect, wherein the preset temperature is a gelatinization temperature of rice.

  According to an eighth aspect of the present invention, when the rice cooking control unit first reaches a third temperature lower than the first reference temperature, the temperature detected by the pan temperature detection unit after the start of the preheating step. The rice cooker as described in any one of the 5th-7th aspect which weakens the thermal power at the time of ON of the said pan heating apparatus is provided.

  According to the rice cooker concerning the 1st mode of the present invention, when the detection temperature of the pan temperature detection part is below the 1st standard temperature when the pan heating device is ON, the pan heating device is switched from ON to OFF. I have to. That is, when the pot heating device is on, the detected temperature of the pot temperature detecting unit, that is, the temperature of the pot is increasing. In the rice cooker according to the first aspect, when the temperature of the pan is rising, the pan heating apparatus is implemented at the first reference temperature lower than the second reference temperature. Thereby, it can suppress that the temperature of the rice in a pan becomes higher than 2nd reference temperature by residual heat.

  Moreover, according to the rice cooker concerning the 1st aspect of this invention, when the detection temperature of a pot temperature detection part is below 2nd reference temperature when a pot heating apparatus is OFF, a pot heating apparatus is turned ON from OFF. I try to switch. That is, when the pot heating device is off, the temperature detected by the pot temperature detecting unit, that is, the temperature of the pot is decreasing. In this state, the second reference temperature is not reached. For this reason, in this 1st aspect, when the detection temperature of a pan temperature detection part is below 2nd reference temperature, it is made to turn on a pan heating apparatus. Thereby, the temperature of the rice in a pan can be brought close to the 2nd standard temperature.

  Therefore, for example, when the second reference temperature is the gelatinization temperature of rice, it is possible to suppress the formation of a layer in which rice grains adhere to each other along the inner surface of the pan, and closer to the gelatinization temperature of rice. Water can be absorbed by rice at temperature. Thereby, the moisture content of rice can be improved and the taste of rice can be further improved. Moreover, since the amount of water left in the pan is reduced by improving the moisture content of rice, the time required for the boiling maintenance step is shortened. As a result, shortening of the rice cooking time can be realized.

  Moreover, according to the rice cooker concerning the 5th aspect of this invention, after the detection temperature of a pan temperature detection part reaches the preset temperature first, after turning off a pan heating apparatus for 1st time, it is 2nd. The temperature control that is turned on for a period of time is repeated a plurality of times. Thereby, it can suppress that the temperature of the rice in a pan becomes higher than the preset temperature. For example, when the preset temperature is the gelatinization temperature of rice, it is possible to suppress the formation of a layer in which rice grains adhere to each other along the inner surface of the pan. Therefore, the taste of rice can be further improved and the cooking time can be shortened.

It is sectional drawing of the rice cooker concerning 1st Embodiment of this invention. It is a figure which shows the control flow in the preheating process of the rice cooker concerning 1st Embodiment of this invention. It is a figure which shows the temperature change of a pan, the drive timing of a pan heating apparatus, and required time when a rice cooking process is implemented using the rice cooker concerning 1st Embodiment of this invention. It is a figure which shows the control flow in the preheating process of the rice cooker concerning 2nd Embodiment of this invention. It is a figure which shows the temperature change of a pan, the drive timing of a pan heating apparatus, and required time when a rice cooking process is implemented using the rice cooker concerning 2nd Embodiment of this invention. It is a figure which shows the temperature change of a pan, the drive timing of a pan heating apparatus, and required time when a rice cooking process is implemented using the conventional common rice cooker. It is sectional drawing which shows the state of the rice in a pot when performing the preheating process using the conventional rice cooker.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

<< First Embodiment >>
The structure of the rice cooker concerning 1st Embodiment of this invention is demonstrated using FIG. FIG. 1 is a sectional view of a rice cooker according to the first embodiment of the present invention.

  As shown in FIG. 1, the rice cooker according to the first embodiment includes a substantially bottomed cylindrical rice cooker body 1 having a pot storage portion 1 a formed therein, and a pot 2 stored in the pot storage portion 1 a. And. A lid body 3 is attached to the upper portion of the rice cooker body 1 so that the upper opening of the rice cooker body 1 can be opened and closed. A substantially disk-shaped inner lid 4 capable of closing the upper opening of the pan 2 is detachably attached to the inside of the lid main body 3 (the side covering the opening of the pan 2).

  The pot storage part 1a of the rice cooker body 1 is composed of an upper frame 1b and a coil base 1c. The upper frame 1b has a cylindrical portion 1ba that is arranged so that a predetermined gap is provided with respect to the side wall of the stored pan 2, and an upper opening of the rice cooker body 1 that protrudes outward from the upper portion of the cylindrical portion 1ba. And a flange portion 1bb fitted to the inner peripheral portion. The coil base 1c is formed in a bottomed cylindrical shape corresponding to the shape of the pan 2, and the upper part thereof is attached to the lower end of the cylindrical portion 1ba of the upper frame 1b.

  A pot heating device 5 for heating (induction heating) the pot 2 is attached to the outer peripheral surface of the coil base 1c. The pan heating device 5 includes a bottom heating coil 5a and a bottom heating coil 5b. The in-bottom heating coil 5a is disposed so as to face the periphery of the center of the bottom of the pan 2 via the coil base 1c. The outside bottom heating coil 5 b is arranged so as to face the corner portion of the bottom of the pan 2 through the coil base 1.

  An opening is provided in the central portion of the bottom of the coil base 1c. In the opening portion, a pan temperature sensor 6 which is an example of a pan temperature detecting unit for measuring the temperature of the pan 2 is disposed so as to be able to contact the bottom of the pan 2 stored in the pan storage unit 1a. . The pan temperature sensor 6 is a contact-type temperature sensor that is less followable than a non-contact type such as an infrared sensor.

  A rice cooker control unit 7 is mounted inside the rice cooker body 1. The rice cooking control part 7 is provided with the memory | storage part which memorize | stores multiple rice cooking program (it is also called a rice cooking sequence) for cooking rice. Each rice cooking program corresponds to one of a plurality of rice cooking menus according to the type of rice. The rice cooking control part 7 controls the drive of each part and each apparatus based on the detection temperature of the pan temperature sensor 6 and the inner lid temperature sensor 10, and performs a rice cooking process. More specifically, the rice cooking control unit 7 receives a user instruction performed using an operation unit (not shown) provided in the lid body 3, a rice cooking program corresponding to the instruction, and a pot Based on the detected temperature of the temperature sensor 6 and the inner lid temperature sensor 10, the drive of each part and each apparatus is controlled, and the rice cooking process is performed.

  A hook 1 d that can be engaged with a hook 3 a of the lid body 3 is provided on the upper part of the front wall of the rice cooker body 1 (upper left side in FIG. 1). A spring 1e is provided between the hook 1d and the cylindrical portion 1ba of the upper frame 1b. The hook 1d is biased forward (left side in FIG. 1) by a spring 1e.

  The lid body 3 includes a hinge axis A. The hinge axis A is an opening / closing axis of the lid body 3, and both ends thereof are fixed to the upper frame 1 c of the rice cooker body 1 so as to be freely rotatable. Around the hinge axis A, a rotation spring (not shown) such as a torsion coil spring is mounted. The rotating spring urges the lid body 3 to rotate in a direction away from the rice cooker body 1 with the hinge axis A as the center of rotation. Accordingly, when the engagement between the hook 3a of the lid body 3 and the hook 1d of the rice cooker body 1 is released, the lid body 3 is automatically rotated by the biasing force, and the upper opening of the rice cooker body 1 is opened. From the closed state to the open state.

  The lid body 3 is provided with a through hole 3c so as to penetrate the vicinity of the center of the lid body 3 in the thickness direction of the lid body 3, and a steam cylinder 8 is detachably attached to the through hole 3c. In the top wall and bottom wall of the steam tube 8, so that excess steam in the pan 2 (more specifically, the upper space not filled with the food to be cooked inside the pan 2) can be discharged to the outside of the rice cooker, Steam escape holes 8a and 8b are provided. Around the through hole 3c on the inner lid 4 side of the lid body 2, an annular steam cylinder packing 9 made of an elastic body such as rubber is attached. The steam cylinder packing 9 is provided in close contact with the inner lid 4 when the inner lid 4 is attached to the lid body 3. The steam cylinder packing 9 may be attached to the inner lid 4 or the steam cylinder 8. The inner lid 4 is provided with one or more steam passage holes 4 a at positions facing the bottom wall of the steam cylinder 8.

  An inner lid temperature sensor 10, which is an example of an inner lid temperature detection unit that detects the temperature of the inner lid 4, is attached to the lid body 3 so as to penetrate the bottom wall 3 b. The inner lid temperature sensor 10 is provided so as to contact the inner lid 4 when the inner lid 4 is attached to the lid body 3.

  An inner lid heating coil 11, which is an example of an inner lid heating device, is attached to the inner surface (inside the lid body) of the bottom wall 3 b of the lid body 3. The inner lid heating coil 11 induction-heats the inner lid 4 under the control of the rice cooking control unit 7. The inner lid 4 is made of a metal such as stainless steel capable of induction heating. The material of the bottom wall 3b of the lid body 3 may be either metal or resin. In the case where the inner lid heating coil 11 is not a induction heating type heating device but a heater type heating device, it is preferable to use a metal as the material of the bottom wall 3b of the lid body 3.

  An annular inner lid packing 12 made of an elastic body such as rubber is attached to the surface of the outer peripheral portion of the inner lid 4 on the pan 2 side. The inner lid packing 12 is provided so as to be in close contact with the flange portion of the pan 2 when the lid body 3 is in the closed state.

  Next, the control flow in the preheating process of the rice cooking control part 7 is demonstrated in detail. FIG. 2 shows a control flow in the preheating process of the rice cooking control unit 7. Here, for convenience of explanation, the inner pan temperature sensor 10 and the inner lid heating coil 11 are not used, but the present invention is not limited to this. The rice cooking control part 7 should just use the inner pot temperature sensor 10 and the inner cover heating coil 11 suitably in each rice cooking process.

  As shown in FIG. 2, the rice cooking control part 7 turns on the pan heating apparatus 5 after the start of a preheating process, and raises the temperature of the pan 2 rapidly. At this time, the heating power of the pan heating device 5 is set to a high heating power (for example, duty ratio 16/16) (step S1).

  Next, the rice cooking control unit 7 determines whether or not the detected temperature Ta of the pan temperature sensor 6 has reached the reference temperature T1 (third reference temperature) (step S2). When the detection temperature Ta of the pan temperature sensor 6 reaches the reference temperature T1, the heating power (heating amount per unit time) when the pan heating device 5 is turned on is weakened (step S3). In addition, it is preferable to set the reference temperature T1 at least 10 ° C. lower than the gelatinization temperature of rice. Thereby, it can suppress that the temperature of a pan becomes more than the gelatinization temperature of rice (for example, 70 degreeC) by the residual heat which generate | occur | produces at the early stage of a preheating process. Here, the reference temperature T1 is 40 ° C.

  Next, the rice cooking control unit 7 determines whether or not the pot heating device 5 is on (step S4). When the pan heating device 5 is on, the reference temperature T is set to T2 (step S5). The reference temperature T2 (first reference temperature) is preferably set to a temperature that is slightly lower (1 to 5 ° C.) than the gelatinization temperature of rice in consideration of the thickness of the pot 2 and thermal conductivity. Here, the reference temperature T2 is set to 58 ° C. Further, when the pot heating device 5 is off, the reference temperature T is set to T3 (step S6). The reference temperature T3 (second reference temperature) is preferably the gelatinization temperature of rice. It is known that the gelatinization temperature of rice is approximately around 60 ° C. If the gelatinization of rice starts even a little, a layer in which the rice grains adhere to each other along the inner surface of the pot 2 can be formed, so the reference temperature T3 is at least equal to or higher than the gelatinization start temperature of rice. Here, the reference temperature T3 is 60 ° C.

  Next, the rice cooking control unit 7 determines whether or not the detected temperature Ta of the pan temperature sensor 6 is equal to or higher than the reference temperature T (step S7). The rice cooking controller 7 switches the pot heating device 5 from on to off when the detected temperature Ta of the pot temperature sensor 6 is equal to or higher than the reference temperature T2 when the pot heating device 5 is on (driving) (step) S8). On the other hand, the rice cooking control unit 7 switches the pot heating device 5 from OFF to ON when the temperature detected by the pot temperature sensor 6 is lower than the reference temperature T3 when the pot heating device 5 is OFF (during driving stop) ( Step S9).

  Next, the rice cooking control unit 7 determines whether or not a predetermined time has elapsed since the start of the preheating process (step S10). When the predetermined time has not elapsed, the process returns to step S4. On the other hand, when the predetermined time has elapsed, the on / off control (steps S4 to S9) of the pot heating device 5 is terminated.

  The following effects can be acquired because the rice cooking control part 7 performs said on-off control.

  When the pot heating device 5 is on, the detected temperature Ta of the pot temperature sensor 6, that is, the temperature of the pot 2 is increasing. In this 1st Embodiment, the rice cooking control part 7 implemented the pan heating apparatus 5 with the reference temperature T2 lower than the reference temperature T3 which is the gelatinization temperature of rice, when this pan heating apparatus 5 is ON. Thereby, it can suppress that the temperature of the rice in the pan 2 becomes higher than the gelatinization temperature of rice by residual heat.

  Moreover, when the pan heating apparatus 5 is OFF, the temperature of the pan 2 is falling. In this 1st Embodiment, when this pan heating apparatus 5 is OFF, the rice cooking control part 7 is a pan when the detection temperature Ta of the pan temperature sensor 6 is below the reference temperature T3 which is the gelatinization temperature of rice. The heating device 5 is turned on. Thereby, the temperature of the rice in the pan 2 can be brought close to the gelatinization temperature of the rice.

  Therefore, for example, when the reference temperature T3 is the gelatinization temperature of rice, it is possible to suppress the formation of a layer in which rice grains adhere to each other along the inner surface of the pan 2, and closer to the gelatinization temperature of rice. Water can be absorbed by rice at temperature. Thereby, the moisture content of rice can be improved and the taste of rice can be further improved. Moreover, since the amount of water left in the pan 2 is reduced by improving the moisture content of the rice, the time required for the boiling maintaining step is shortened. As a result, shortening of the rice cooking time can be realized.

  Note that the shorter the on / off switching interval of the pan heating device 5 is, the more preferable the temperature change of the pan 2 can be within the range of the reference temperature T2 and the reference temperature T3. Note that with the current technology, it is difficult to make the on-off switching interval of the pot heating device 5 less than 0.6 seconds.

  Next, operation | movement and an effect | action of the rice cooker concerning this 1st Embodiment comprised as mentioned above are demonstrated, referring FIG. FIG. 3: is a figure which shows the temperature change of a pan, the drive timing of a pan heating apparatus, and required time when a rice cooking process is implemented using the rice cooker concerning this 1st Embodiment. In FIG. 3, the solid line indicates the temperature transition of the pan 2. Here, the temperature of the pan 2 is handled as a transition similar to the cooking object in the pan 2.

  First, when the user puts rice and water into the pan 2 and selects a rice cooking menu with an operation unit (not shown) provided in the lid body 3, the rice cooking start is instructed. The rice cooking process is started under the control of the control unit 7. When the rice cooking process is started, first, the preheating process is started.

  The preheating step is a step in which the rice is preliminarily absorbed by water soaked in water at a temperature lower than the gelatinization temperature so that the center of the rice can be sufficiently gelatinized in the subsequent steps. When this preheating process is started, the rice cooking control unit 7 turns on (drives) the pot heating device 5 after a predetermined time (for example, 8 minutes) and rapidly increases the temperature of the pot 2. At this time, the heating power of the pot heating device 5 is set to a high heating power (for example, a duty ratio of 16/16). Here, the pan heating device 5 is turned on after a predetermined time has elapsed since the start of the preheating step, but the pan heating device 5 may be turned on immediately after the start of the preheating step.

  When the detected temperature Ta of the pan temperature sensor 6 reaches the reference temperature T1 or more, the rice cooking control unit 7 weakens the heating power of the pot heating device 5, that is, from high heating power to low heating power (for example, a duty ratio of less than 16/16). To do. Thereafter, when the detected temperature Ta of the pan temperature sensor 6 reaches the reference temperature T2 or higher, the rice cooking control unit 7 switches the pan heating device 5 from on to off. Thereby, the temperature of the pan 2 falls.

  After a predetermined time (for example, 0.6 seconds) has elapsed since the pan heating device 5 was turned off, when the detected temperature Ta of the pan temperature sensor 6 is equal to or lower than the reference temperature T3, the rice cooking control unit 7 Switch from off to on. Thereby, the temperature of the pan 2 rises. In addition, when the detection temperature Ta of the pan temperature sensor 6 is higher than the reference temperature T3, the rice cooking control unit 7 keeps the pan heating device 5 off.

  After a predetermined time (for example, 0.6 seconds) has elapsed since the pan heating device 5 was turned on, when the detected temperature Ta of the pan temperature sensor 6 is equal to or higher than the reference temperature T2, the rice cooking control unit 7 Switch from off to on. Thereby, the temperature of the pan 2 rises. In addition, when the detection temperature Ta of the pan temperature sensor 6 is lower than the reference temperature T2, the rice cooking control unit 7 keeps the pan heating device 5 on.

  The rice cooking control unit 7 repeats the on / off switching operation of the pan heating device 5 for a predetermined time (for example, 9 minutes), and then turns off the pan heating device 5 for a predetermined time (for example, 6 minutes) to end the preheating step. Note that the on / off switching operation of the pan heating device 5 may be repeated until the end time of the preheating step.

  If the time (for example, 15 minutes) preset according to the selected rice cooking menu passes from the start of a preheating process, it will transfer to a temperature rising process.

  The temperature raising process is a process in which the pot 2 is heated at a stretch with high heating power to bring the water in the pot 2 to a boiling state. In this temperature raising step, the rice cooking control unit 7 rapidly heats the pan 2 so that the detection temperature T4 of the pan temperature sensor 6 becomes the boiling temperature T4 of water (about 100 ° C.). Control. When the temperature detected by the pan temperature sensor 6 reaches the boiling temperature T4 by performing the temperature raising step, the process proceeds to the boiling maintaining step. The time required for this temperature raising step varies depending on the amount of cooked rice (amount of food to be cooked in the pan 2) and the like. In addition, the amount of rice cooking can be determined automatically from the time required for the temperature raising step. For example, the amount of cooked rice can be automatically determined by examining the time difference from when the temperature detected by the pan temperature sensor 6 reaches 80 ° C. until the temperature detected by the inner lid temperature sensor 10 reaches 80 ° C.

  A boiling maintenance process is a process of maintaining the boiling state of the water in the pan 2, gelatinizing rice starch, and raising the gelatinization degree to about 50% to 60%. In this boiling maintenance process, the rice cooking control part 7 controls the pan heating apparatus 5 so that the boiling state of the water in the pan 2 may be maintained. More specifically, the rice cooking control unit 7 performs duty control that repeats on / off of the pot heating device 5 at regular time intervals, and intermittently heats the pot 2.

  In the boiling maintenance step, water is continuously boiled, and a large amount of steam at about 100 ° C. is generated. The generated steam passes through the steam passage hole 4a of the inner lid 4 and the steam escape holes 8a and 8b of the steam cylinder 8, and is discharged to the outside of the rice cooker. Thereby, when most of the water in the pot 2 runs out, the temperature of the bottom surface of the pot 2 rises above the boiling point of water. When the pan temperature sensor 6 detects that the temperature of the bottom surface of the pan 2 has reached a predetermined temperature T5 (for example, 130 ° C.) equal to or higher than the boiling point, the process proceeds to a steaming process. In addition, the time which a boiling maintenance process requires changes with rice cooking amounts etc.

  The steaming process is a process of evaporating excess water using preheating and raising the degree of gelatinization of rice to nearly 100%. In this steaming step, the rice cooking control unit 7 controls the pot heating device 5 so as to heat the pot 2 every time the temperature of the pot 2 falls below a certain temperature. More specifically, the rice cooking control part 7 performs duty control which repeats on-off of the pan heating apparatus 5 by a fixed time interval similarly to a boiling maintenance process, and heats the pan 2 intermittently. If the predetermined time (for example, 8 minutes) according to the amount of rice cooking passes from the start of a steaming process, a steaming process will be complete | finished (namely, rice cooking process will be complete | finished).

  According to the first embodiment, when the pot heating device 5 is on and the detected temperature of the pan temperature sensor 6 becomes the reference temperature T2 lower than the reference temperature T3, the pot heating device 5 is implemented. It can suppress that the temperature of the rice in the pan 2 becomes higher than the reference temperature T3 due to residual heat. Further, according to the first embodiment, when the pot heating device 5 is off and the detected temperature Ta of the pot temperature sensor 6 is lower than the reference temperature T3, the pot heating device 5 is turned on. The temperature of the rice can be brought close to the reference temperature T3. That is, according to the first embodiment, even if a contact-type temperature sensor with poor followability is used as the pan temperature sensor 6, the temperature of the pan 2 can be set to a substantially intended temperature. Accordingly, it is possible to suppress the formation of a layer in which rice grains adhere to each other along the inner surface of the pot 2 and to allow the rice to absorb water at a temperature closer to the gelatinization temperature of the rice. Thereby, the moisture content of rice can be improved and the taste of rice can be further improved. Moreover, since the amount of water left in the pan 2 is reduced by improving the moisture content of the rice, the time required for the boiling maintaining step is shortened. As a result, shortening of the rice cooking time can be realized.

  In addition, when the rice cooking process was implemented with the conventional rice cooker, the moisture content of the rice at the time of completion | finish of a preheating process was about 30%. On the other hand, when the rice cooking time was the same and the rice cooking process was implemented with the rice cooker concerning this 1st Embodiment, the moisture content of the rice at the time of completion | finish of a preheating process was about 33%. Therefore, it was confirmed that the moisture content of rice was improved by about 3% by performing the on / off control. In addition, it has also been confirmed that the time required for the boiling maintenance process is shortened by 1 minute due to the improvement of the moisture content of rice in the preheating process. It has also been confirmed that energy savings of about 3% have been realized in the entire rice cooking process by reducing the time required for the boiling maintenance process.

  In the above description, when the detected temperature Ta of the pan temperature sensor 6 reaches the reference temperature T2 or T3, the pan heating device 5 is switched on and off, but the present invention is not limited to this. What is necessary is just to make it the temperature of the pan 2 change with the waveform as shown in FIG. 3, ie, the waveform which swings between the reference temperature T2 and the reference temperature T3. For example, the timing at which the detected temperature Ta of the pan temperature sensor 6 is predicted to be higher than the reference temperature T2 when the pan heating device 5 is on, and the detected temperature of the pan temperature sensor 6 when the pan heating device 5 is off. The timing at which Ta is predicted to be lower than the reference temperature T3 is stored in advance in the storage unit of the rice cooking control unit 7 in association with the rice cooking program, and the pot heating device 5 is turned on / off according to those timings. Good.

<< Second Embodiment >>
FIG. 4: has shown the control flow in the preheating process of the rice cooker concerning 2nd Embodiment of this invention. FIG. 5: is a figure which shows the temperature change of a pan, the drive timing of a pan heating apparatus, and required time when a rice cooking process is implemented using the rice cooker concerning 2nd Embodiment of this invention. The difference between the rice cooker of the second embodiment and the rice cooker of the first embodiment is that the rice cooking control unit 7 performs the control flow shown in FIG. 4 instead of the control flow shown in FIG. 2 in the preheating step. is there. Here, for convenience of explanation, the inner pot temperature sensor 10 and the inner lid heating coil 11 are not used.

  As shown in FIG. 2, the rice cooking control part 7 turns on the pan heating apparatus 5 after the start of a preheating process, and raises the temperature of the pan 2 rapidly. At this time, the heating power of the pan heating device 5 is set to a high heating power (for example, duty ratio 16/16) (step S11).

  Next, the rice cooking control unit 7 determines whether or not the detected temperature Ta of the pan temperature sensor 6 has reached the reference temperature T1 (step S12). When the detection temperature Ta of the pan temperature sensor 6 reaches the reference temperature T1, the heating power (heating amount per unit time) when the pan heating device 5 is turned on is weakened (step S13).

  Next, the rice cooking control unit 7 determines whether or not the detected temperature Ta of the pan temperature sensor 6 is equal to or higher than the reference temperature T3 (step S14). When the detected temperature Ta of the pan temperature sensor 6 becomes equal to or higher than the reference temperature T3, the rice cooking control unit 7 switches the pan heating device 5 from on to off (step S15). Thereby, the temperature of the pan 2 falls.

  Next, it is determined whether or not the temperature detection temperature Ta of the pan temperature sensor 6 is equal to or lower than the reference temperature T3 (step S16). When the detected temperature Ta of the pot temperature sensor 6 becomes equal to or lower than the reference temperature T3, the rice cooking control unit 7 first turns off the pot heating device 5 so that the detected temperature Ta of the pot temperature sensor 6 becomes lower than the reference temperature T3. After the time continues, the pot heating device 5 is turned on for a second time so that the detected temperature Ta of the pot temperature detecting unit 6 returns to the reference temperature T3 (step S17). The first time is, for example, 6 seconds, and the second time is, for example, 2 seconds.

  Next, the rice cooking control unit 7 determines whether or not a predetermined time has elapsed since the start of the preheating process (step S18). When the predetermined time has not elapsed, the process returns to step S17. In other words, the rice cooking control unit 7 repeats the control (hereinafter referred to as temperature control) that is turned on for the second time after turning off the pot heating device 5 for the first time until the predetermined time elapses. When the predetermined time has elapsed, the temperature control is terminated.

  According to the second embodiment, the rice cooking control unit 7 performs the temperature adjustment control, so that the temperature of the pan 2 changes in a waveform as shown in FIG. That is, according to the second embodiment, even if a contact-type temperature sensor with poor followability is used as the pan temperature sensor 6, the temperature of the pan 2 can be set to a substantially intended temperature. Therefore, the period in which the temperature of the pot 2 is equal to or higher than the gelatinization temperature of the rice can be shortened, and the formation of a layer in which rice grains adhere to each other along the inner surface of the pot 2 can be suppressed. Further, the shorter the time required for one temperature control (step S17), the more water can be absorbed by the rice at a temperature closer to the gelatinization temperature of the rice. Therefore, the moisture content of rice can be improved, and the taste of rice can be further improved. Moreover, since the amount of water left in the pan is reduced by improving the moisture content of rice, the time required for the boiling maintenance step is shortened. As a result, shortening of the rice cooking time can be realized.

  In addition, this invention is not limited to said each embodiment, It can implement in another various aspect. For example, in each of the above embodiments, in the preheating process, when the detected temperature Ta of the pan temperature sensor 6 is equal to or higher than the reference temperature T1, the heating power of the pot heating device 5 is switched from high heating power to low heating power. The invention is not limited to this. Even if the heating power of the pot heating device 5 is not switched from high heating power to low heating power, by controlling the pot heating device 5 as in the above embodiments (steps S4 to S9 or step S17), the pot can be compared with the conventional one. The period during which the temperature of 2 is equal to or higher than the gelatinization temperature of rice can be shortened.

  Further, in each of the above embodiments, only in the preheating step, the temperature of the pan 2 is changed in the vicinity of a constant reference temperature (= T3) and is suppressed from becoming higher than the reference temperature. Is not limited to this. For example, the rice cooking control unit 7 controls the pan heating device 5 to be repeatedly turned on and off at regular intervals in the boiling maintenance process or the steaming process. For this reason, the temperature of the pan 2 changes so as to swing with a certain reference temperature as a reference. Even if the control as in each of the above-described embodiments is performed in such a process, it is possible to obtain not only an effect of improving the rice taste but also shortening the cooking time.

  Further, for example, in the steaming process, if the temperature change of the pan 2 is large, there may be a problem that unintended burning occurs in the rice or the surface is excessively dried. If the control as in each of the above embodiments is performed in this steaming step, the temperature of the pan 2 can be brought to a substantially intended temperature even if a contact-type temperature sensor with poor followability is used as the pan temperature sensor 6. , Can prevent scorching and excessive drying of the surface. In addition, the time required for the steaming process can be shortened, and the tint color can be adjusted.

  It is to be noted that, by appropriately combining any of the various embodiments, the effects possessed by them can be produced.

  The rice cooker according to the present invention is particularly useful for a rice cooker used for home use because it can improve the taste of rice and shorten the rice cooking time.

DESCRIPTION OF SYMBOLS 1 Rice cooker body 2 Pan 3 Lid body 4 Inner lid 5 Pan heating device 6 Pan temperature sensor (pan temperature detection part)
7 Rice Cooking Control Unit 8 Steam Cylinder 9 Steam Cylinder Packing 10 Inner Lid Temperature Sensor (Inner Lid Temperature Detection Unit)
11 Inner lid heating coil (Inner lid heating device)
12 Inner lid packing A Hinge shaft

Claims (8)

A pot with rice and water,
A pot heating device for heating the pot;
A pan temperature detector for detecting the temperature of the pan;
A rice cooking control unit that controls on / off of the pan heating device based on the detected temperature of the pan temperature detection unit, and performs a rice cooking process including a preheating process, a temperature rising process, a boiling maintenance process, and a steaming process,
With
The rice cooking control unit
When the pan heating device is on, when the temperature detected by the pan temperature detection unit is equal to or higher than the first reference temperature, the pan heating device is switched from on to off,
When the pan heating device is off, the pan heating device is switched from off to on when the detected temperature of the pan temperature detecting unit is equal to or lower than a second reference temperature that is higher than the first reference temperature. ,
rice cooker. In the preheating step, the rice cooking control unit is
When the temperature detected by the pan temperature detection unit is equal to or higher than the first reference temperature when the pan heating device is on, the pan heating device is switched from on to off, and when the pan heating device is off When the detected temperature of the pan temperature detection unit is equal to or lower than the second reference temperature, the pan heating device is switched from off to on.
The rice cooker according to claim 1.   The rice cooker according to claim 1, wherein the second reference temperature is a gelatinization temperature of rice.   When the temperature detected by the pan temperature detection unit first reaches a third temperature lower than the first reference temperature after the start of the preheating step, the rice cooking control unit is a heating power when the pan heating device is turned on. The rice cooker as described in any one of Claims 1-3 which weakens. A pot with rice and water,
A pot heating device for heating the pot;
A pan temperature detector for detecting the temperature of the pan;
A rice cooking control unit that controls on / off of the pan heating device based on the detected temperature of the pan temperature detection unit, and performs a rice cooking process including a preheating process, a temperature rising process, a boiling maintenance process, and a steaming process,
With
The rice cooking control unit
After the detection temperature of the pan temperature detection unit first reaches a preset temperature,
After the pan heating device is turned off for a first time such that the detected temperature of the pan temperature detecting unit is lower than the preset temperature, the detected temperature of the pan temperature detecting unit becomes the preset temperature. To turn on the pan heating device for a second time, repeat the temperature control multiple times,
rice cooker.   The said rice cooking control part is a rice cooker of Claim 5 which performs the said temperature control in the said preheating process.   The rice cooker according to claim 6, wherein the preset temperature is a gelatinization temperature of rice.   When the temperature detected by the pan temperature detection unit first reaches a third temperature lower than the first reference temperature after the start of the preheating step, the rice cooking control unit is a heating power when the pan heating device is turned on. The rice cooker as described in any one of Claims 5-7 which weakens.

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