Cooking appliance

Abstract

To provide a cooking device capable of having a high moisture content of a food material immediately after cooking, and capable of retaining sufficient moisture inside a food material even when the food material is frozen, and then thawed and warmed.SOLUTION: A rice cooker of the present invention can select one of two types of operation modes of "normal mode" and "freezing mode." A control part of the rice cooker causes the pressure in an internal space of an inner pot at an initial stage of a boiling keeping process S3 when the "freezing mode" is selected to be higher than the pressure in the internal space at the initial stage of the boiling keeping process S3 when the "normal mode" is selected. Thereby, it is possible to increase a moisture content inside the rice cooked in the "freezing mode" so that even in the case where the rice cooked in the "freezing mode" is frozen, and thawed and warmed, sufficient moisture can be retained inside the rice.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a cooker for cooking food by heating.

Background Art

[0002] Conventionally, as an example of a cooker that houses food inside and cooks it by heating, a rice cooker is known. The rice cooker houses rice and water inside and cooks the rice by heating and pressurizing. Conventional rice cookers are described, for example, in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There are cases where the cooked rice after cooking is frozen and stored, and later thawed and warmed using a microwave oven or the like. In that case, there is a problem that the amount of moisture inside the rice decreases during the process of freezing, thawing, and warming the rice. In addition, there is also a problem that the moisture that has come out of the rice adheres to the surface of the rice, making the surface of the rice sticky, or the rice grains adhere to each other and become dumpling-like.

[0005] Regarding this point, Patent Document 1 describes a rice cooker having a rice cooking mode for freezing. However, when the rice cooking mode for freezing is selected in the rice cooker of Patent Document 1, the rice is cooked so that the water content of the rice is lower than usual. In this case, since the cooked rice is harder than usual, there is a problem that a good taste cannot be obtained immediately after cooking.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a cooker in which the water content of the food immediately after cooking is high and sufficient moisture can be retained inside the food even when the food is frozen and then thawed and warmed.

Means for Solving the Problem

[0007] The present invention is a cooker for cooking food materials, comprising an inner pot capable of containing the food materials and water, a main body part in which the inner pot is set, a lid body that seals the internal space of the inner pot by covering the upper part of the main body part, a heating part for heating the inner pot, a pressure regulating part for adjusting the pressure of the internal space, and a control part for controlling the heating part and the pressure regulating part. The control part can select two operation modes, namely a normal mode and a freezing mode. The control part executes a temperature rising process of raising the temperature of the inner pot to the boiling temperature, and after the temperature rising process, a boiling maintaining process of maintaining the temperature of the inner pot at the boiling temperature. The pressure of the internal space at the initial stage of the boiling maintaining process when the freezing mode is selected is higher than the pressure of the internal space at the initial stage of the boiling maintaining process when the normal mode is selected.

[0008] According to the present invention, the pressure of the internal space of the inner pot at the initial stage of the boiling maintaining process when the freezing mode is selected is made higher than the pressure of the internal space of the inner pot at the initial stage of the boiling maintaining process when the normal mode is selected. Thereby, the water content inside the food material cooked in the freezing mode can be increased. Therefore, even when the food material cooked in the freezing mode is frozen and then thawed and warmed, sufficient moisture can be retained inside the food material.

[0009] Also, it is desirable that the pressure of the internal space in the temperature rising process when the freezing mode is selected is higher than the pressure of the internal space in the temperature rising process when the normal mode is selected. Thereby, the water content inside the food material cooked in the freezing mode can be increased more.

[0010] Also, it is desirable that the time of the boiling maintaining process when the freezing mode is selected is shorter than the time of the boiling maintaining process when the normal mode is selected. Thereby, over-pressurization of the food material can be suppressed, and the stickiness on the surface of the food material can be reduced. Therefore, when the food material cooked in the freezing mode is frozen and then thawed and warmed, it is possible to suppress the surface of the food material from being sticky.

[0011] Further, after the boiling maintenance step, the control unit further executes a cooking-up step of raising the temperature of the inner pot again while maintaining the pressure in the internal space at a pressure higher than the atmospheric pressure, and it is desirable that the time of the cooking-up step when the freezing mode is selected is shorter than the time of the cooking-up step when the normal mode is selected. Thereby, over-pressurization of the food ingredients can be suppressed, and the stickiness on the surface of the food ingredients can be reduced. Therefore, when the food ingredients cooked in the freezing mode are frozen and then thawed and warmed, it is possible to suppress the surface of the food ingredients from being sticky.

[0012] Further, after the cooking-up step, the control unit further executes a double-cooking step of raising the temperature of the inner pot and the pressure in the internal space again, and it is desirable that the time of the double-cooking step when the freezing mode is selected is shorter than the time of the double-cooking step when the normal mode is selected. Thereby, over-pressurization of the food ingredients can be suppressed, and the stickiness on the surface of the food ingredients can be reduced. Therefore, when the food ingredients cooked in the freezing mode are frozen and then thawed and warmed, it is possible to suppress the surface of the food ingredients from being sticky.

[0013] Further, when the normal mode is selected, the control unit further executes a double-cooking step of raising the temperature of the inner pot and the pressure in the internal space again after the cooking-up step, and when the freezing mode is selected, it is desirable that the double-cooking step is not executed. Thereby, over-pressurization of the food ingredients can be suppressed, and the stickiness on the surface of the food ingredients can be reduced. Therefore, when the food ingredients cooked in the freezing mode are frozen and then thawed and warmed, it is possible to suppress the surface of the food ingredients from being sticky.

[0014] In addition, after the cooking step, the control unit further executes a double-cooking step of raising the temperature of the inner pot again. When the normal mode is selected, in the double-cooking step, the pressure in the internal space is raised again. When the freezing mode is selected, in the double-cooking step, the pressure in the internal space is not raised again. It is desirable that the time of the double-cooking step when the freezing mode is selected is shorter than the time of the double-cooking step when the normal mode is selected. This can suppress excessive pressure on the food ingredients and reduce the stickiness on the surface of the food ingredients. Therefore, when the food ingredients cooked in the freezing mode are frozen and then thawed and warmed, it is possible to suppress the stickiness of the surface of the food ingredients.

Advantages of the Invention

[0015] According to the present invention, the pressure in the internal space of the inner pot at the initial stage of the boiling maintenance step when the freezing mode is selected is made higher than the pressure in the internal space of the inner pot at the initial stage of the boiling maintenance step when the normal mode is selected. Thereby, the moisture content inside the food ingredients cooked in the freezing mode can be increased. Therefore, even when the food ingredients cooked in the freezing mode are frozen and then thawed and warmed, sufficient moisture can be retained inside the food ingredients.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] <1. Configuration of the rice cooker> FIG. 1 is a diagram showing the configuration of the rice cooker 1. This rice cooker 1 is an embodiment of the cooking appliance according to the present invention. The rice cooker 1 cooks rice, which is an example of food ingredients, by heating it together with water. As shown in FIG. 1, the rice cooker 1 includes an inner pot 10, a main body 20, a lid 30, a heating unit 40, a pressure regulating unit 50, a pot temperature sensor 61, a lid temperature sensor 62, a pressure sensor 70, a control unit 80, and an operation unit 90.

[0019] The inner pot 10 is a bottomed cylindrical container capable of accommodating rice and water inside. The inner pot 10 has an inner layer portion and an outer layer portion joined to the outer surface of the inner layer portion. The inner layer portion is made of aluminum or copper with high thermal conductivity. The outer layer portion is made of a ferromagnetic material such as stainless steel that can be induction-heated.

[0020] The main body 20 is a housing capable of accommodating the inner pot 10. The main body 20 has a receiving recess 21 that is recessed downward from its upper surface. The bottom and outer peripheral portions of the receiving recess 21 are formed of a non-conductive material. The inner pot 10 is detachable from the receiving recess 21. When the rice cooker 1 is in use, the inner pot 10 is set in the receiving recess 21. Also, after the rice cooker 1 is used, the inner pot 10 can be removed from the receiving recess 21 and washed.

[0021] The lid 30 is rotatably connected to the main body 20 by a hinge 22 provided at the rear of the main body 20. The lid 30 rotates about the hinge 22 between a closed position (the solid line position in FIG. 1) that covers the upper part of the main body 20 and an upright position (the two-dot chain line position in FIG. 1) that stands substantially perpendicular to the main body 20.

[0022] On the lower surface of the lid body 30, an annular packing 31 is provided. When the lid body 30 is in the closed position, the upper opening of the inner pot 10 set in the above-described accommodation recess 21 is closed by the lid body 30. Then, the packing 31 of the lid body 30 adheres to the edge of the opening of the inner pot 10. Thereby, the internal space 13 of the inner pot 10 is sealed. When the lid body 30 is in the upright position, the upper part of the inner pot 10 is opened, and the inner pot 10 can be attached to and detached from the accommodation recess 21.

[0023] The heating unit 40 is a means for heating the inner pot 10. The heating unit 40 is provided at the lower part of the accommodation recess 21. The heating unit 40 is, for example, an induction heating coil. When the rice cooker 1 is in use, a high-frequency current is supplied to the induction heating coil, and magnetic field lines are generated from the induction heating coil. Then, the inner pot 10 generates heat by electromagnetic induction, and the rice and water accommodated inside the inner pot 10 are heated.

[0024] The pressure regulating unit 50 is a means for adjusting the pressure (atmospheric pressure) in the internal space 13 of the inner pot 10. The pressure regulating unit 50 is provided on the lid body 30. The pressure regulating unit 50 has a flow path 51 that communicates the internal space 13 of the inner pot 10 with the outside, and a valve 52 that adjusts the opening area of the flow path 51. The valve 52 is constituted by, for example, a pressure regulating ball provided in the flow path 51, a spring that presses the pressure regulating ball, and a plunger that adjusts the position of the pressure regulating ball. Note that the pressure regulating unit 50 may be constituted by a plurality of valves 52.

[0025] The pressure regulating unit 50 can adjust the pressure in the internal space 13 in multiple stages according to a signal supplied from the control unit 80. Specifically, the pressure regulating unit 50 has an open state in which the flow path 51 is opened regardless of the pressure in the internal space 13, an intermediate throttle state in which the flow path 51 is opened when the pressure in the internal space 13 reaches an intermediate pressure (for example, 1.15 atm) higher than the atmospheric pressure (1 atm), and a maximum throttle state in which the flow path 51 is opened when the pressure in the internal space 13 reaches a maximum pressure (for example, 1.3 atm) higher than the intermediate pressure. The state of the valve 52 can be switched between these states.

[0026] The pot temperature sensor 61 is provided near the accommodation recess 21. The lid temperature sensor 62 is provided on the lid body 30. The pot temperature sensor 61 and the lid temperature sensor 62 are electrically connected to the control unit 80. The pot temperature sensor 61 measures the temperature of the inner pot 10 and outputs a signal indicating the measured value to the control unit 80. The lid temperature sensor 62 measures the temperature of the lid body 30 that changes due to the steam generated from the internal space 13 of the inner pot 10 and outputs a signal indicating the measured value to the control unit 80.

[0027] The pressure sensor 70 is a sensor that measures the pressure in the internal space 13 of the inner pot 10. The pressure sensor 70 is provided on the lid body 30. The pressure sensor 70 is electrically connected to the control unit 80. The pressure sensor 70 measures the pressure in the internal space 13 of the inner pot 10 and outputs a signal indicating the measured value to the control unit 80.

[0028] The control unit 80 is a means for controlling the heating unit 40 and the pressure regulating unit 50. The control unit 80 is provided inside the main body 20. The control unit 80 is constituted by, for example, a microcomputer mounted on a circuit board. As shown in FIG. 1, the control unit 80 is electrically connected to the heating unit 40, the pressure regulating unit 50, the pot temperature sensor 61, the lid temperature sensor 62, the pressure sensor 70, and the operation unit 90. The control unit 80 controls the operations of the heating unit 40 and the pressure regulating unit 50 based on a preset program and the detection signals of the sensors 61, 62, 70. Thereby, the preheating steps S1 to unevenness steps S8 described later are executed.

[0029] The operation unit 90 is a means for receiving operation inputs from the user. The operation unit 90 is provided on the upper surface of the lid body 30 or the outer surface of the main body 20. For the operation unit 90, for example, a touch panel display having both a display function and an input function is used. However, the operation unit 90 may be a button or the like that does not have a display function.

[0030] This rice cooker 1 can cook rice in at least two operating modes: "Normal Mode" and "Freezing Mode". "Normal Mode" is a standard rice-cooking operating mode. "Freezing Mode" is an operating mode assuming that the cooked rice can be eaten as it is, or can be deliciously eaten even after being frozen, thawed, and warmed. In "Freezing Mode", the temperature of the inner pot 10 and the pressure in the internal space 13 are changed in a different manner from that in "Normal Mode".

[0031] The user of the rice cooker 1 selects one of "Normal Mode" and "Freezing Mode" by operating the operation unit 90. Then, information on the selected operating mode is input from the operation unit 90 to the control unit 80. The control unit 80 controls the operations of the heating unit 40 and the pressure regulating unit 50 according to the input operating mode.

[0032] <2. Operations of the Rice Cooker> Subsequently, the operation of cooking rice (heating and cooking) performed by the above-described rice cooker 1 will be described. FIG. 2 is a flowchart showing the procedure of cooking rice. FIG. 3 is a graph showing changes in the power supplied to the heating unit 40, the temperature of the inner pot 10, and the pressure in the internal space 13 when "Normal Mode" is selected. FIG. 4 is a graph showing changes in the power supplied to the heating unit 40, the temperature of the inner pot 10, and the pressure in the internal space 13 when "Freezing Mode" is selected. The horizontal axis of the graphs in FIGS. 3 and 4 indicates the time (minutes) after the start of rice cooking. The vertical axes of the graphs in FIGS. 3 and 4 indicate the supplied power (W), the temperature (°C), and the pressure (atm).

[0033] When cooking rice with this rice cooker 1, first, the user puts rice and water into the inner pot 10. Then, the user sets the inner pot 10 in the accommodation recess 21 of the main body 20 and closes the lid 30. Thereafter, the user operates the operation unit 90 to select one of "Normal Mode" and "Freezing Mode". Then, rice cooking starts in the selected operating mode.

[0034] As shown in FIGS. 2 to 4, the control unit 80 first executes the preheating step S1. The preheating step S1 is a step of raising the temperature inside the inner pot 10 and causing the rice to absorb water. In the preheating step S1, the control unit 80 operates the heating unit 40. Specifically, the control unit 80 supplies current to the induction heating coil at a first duty ratio (for example, 30 to 70%). Also, the power supplied to the induction heating coil is set to a first power (for example, 900 to 1000 W). Thereby, the temperature of the inner pot 10 is maintained at a predetermined preheating temperature (for example, 40 to 50°C).

[0035] When a predetermined time has elapsed since the start of the preheating step S1, the control unit 80 ends the preheating step S1.

[0036] Next, the control unit 80 executes the temperature rising step S2. The temperature rising step S2 is a step of raising the temperature of the inner pot 10 to the boiling temperature at which the water inside boils. In the temperature rising step S2, the control unit 80 operates the heating unit 40 at a higher output than in the preheating step S1. Specifically, the control unit 80 supplies current to the induction heating coil at a second duty ratio (for example, 100%) higher than the first duty ratio. Also, the power supplied to the induction heating coil is set to a second power (for example, 1200 W) higher than the first power. Thereby, the temperature of the inner pot 10 rises from the preheating temperature to the boiling temperature (for example, 100°C). Therefore, the water inside the inner pot 10 starts to boil.

[0037] When the "normal mode" is selected, the control unit 80 maintains the valve 52 of the pressure regulating unit 50 in the open state in the temperature rising step S2. For this reason, when the "normal mode" is selected, as shown in FIG. 3, the pressure in the internal space 13 of the inner pot 10 in the temperature rising step S2 is maintained at the atmospheric pressure (1 atm).

[0038] On the one hand, when the "freezing mode" is selected, the control unit 80 switches the valve 52 of the pressure regulating unit 50 from the open state to the maximum throttle state in the temperature rising step S2. Then, the pressure in the internal space 13 of the inner pot 10 increases due to the steam generated from the water in the inner pot 10. As a result, as shown in FIG. 4, the pressure in the internal space 13 in the temperature rising step S2 gradually increases from the atmospheric pressure to the maximum pressure (for example, 1.3 atm).

[0039] In this way, in the "freezing mode", the pressure in the internal space 13 of the inner pot 10 is increased in the temperature rising step S2. Therefore, the pressure in the internal space 13 in the temperature rising step S2 when the "freezing mode" is selected is higher than the pressure in the internal space 13 in the temperature rising step S2 when the "normal mode" is selected. Thereby, in the "freezing mode", the moisture content inside the rice can be increased more than in the "normal mode".

[0040] When the temperature of the lid 30 input from the lid temperature sensor 62 reaches a predetermined transition temperature (for example, 60 to 70 ° C), the control unit 80 ends the temperature rising step S2.

[0041] Next, the control unit 80 executes the boiling maintenance step S3. The boiling maintenance step S3 is a step of maintaining the water in the inner pot 10 in a boiling state. In the boiling maintenance step S3, the control unit 80 operates the heating unit 40 at an output higher than that in the preheating step S1 and lower than that in the temperature rising step S2. Specifically, the control unit 80 supplies a current to the induction heating coil at a third duty ratio (for example, 50 to 80%) that is higher than the first duty ratio and lower than the second duty ratio. The power supplied to the induction heating coil remains at the second power. Thereby, the temperature of the inner pot 10 is maintained at the boiling temperature. Therefore, the water in the inner pot 10 is maintained in a boiling state.

[0042] When the "Normal Mode" is selected, in the boiling maintenance step S3, the control unit 80 first switches the valve 52 of the pressure regulating unit 50 from the open state to the intermediate throttle state. Then, the pressure in the internal space 13 of the inner pot 10 rises due to the steam generated from the water in the inner pot 10. As a result, as shown in FIG. 3, the pressure in the internal space 13 in the first half of the boiling maintenance step S3 becomes the intermediate pressure (for example, 1.15 atm).

[0043] Also, when the "Normal Mode" is selected, the control unit 80 switches the valve 52 of the pressure regulating unit 50 to the maximum throttle state from the middle of the boiling maintenance step S3. Then, the pressure in the internal space 13 of the inner pot 10 further rises due to the steam generated from the water in the inner pot 10. As a result, as shown in FIG. 3, the pressure in the internal space 13 in the second half of the boiling maintenance step S3 becomes the maximum pressure (for example, 1.3 atm).

[0044] On the other hand, when the "Freezing Mode" is selected, the control unit 80 maintains the valve 52 of the pressure regulating unit 50 in the maximum throttle state in the boiling maintenance step S3. Therefore, when the "Freezing Mode" is selected, as shown in FIG. 4, the pressure in the internal space 13 of the inner pot 10 is maintained at the maximum pressure (for example, 1.3 atm) from the start to the end of the boiling maintenance step S3.

[0045] In this way, in this rice cooker 1, the pressure in the internal space 13 at the initial stage of the boiling maintenance step S3 when the "Freezing Mode" is selected is made higher than the pressure in the internal space 13 at the initial stage of the boiling maintenance step S3 when the "Normal Mode" is selected. Thereby, the moisture content inside the rice cooked in the "Freezing Mode" can be increased more.

[0046] As boiling progresses and the amount of water in the inner pot 10 decreases, the temperature of the inner pot 10 becomes higher than the boiling temperature. When the temperature of the inner pot 10 input from the pot temperature sensor 61 reaches a predetermined threshold temperature T (for example, 110 °C) higher than the boiling temperature, the control unit 80 ends the boiling maintenance step S3.

[0047] When "Normal Mode" is selected and when "Freezing Mode" is selected, the value of the threshold temperature T may be the same. However, it is desirable that the threshold temperature T when "Freezing Mode" is selected is lower than the threshold temperature T when "Normal Mode" is selected. By doing so, the time of the boiling maintenance step S3 when "Freezing Mode" is selected becomes shorter than the time of the boiling maintenance step S3 when "Normal Mode" is selected.

[0048] In the boiling maintenance step S3, the starch contained in the rice gelatinizes. As a result, the sweet component of the rice increases and the taste of the rice improves. However, if too much pressure is applied during cooking, the stickiness on the surface of the rice becomes strong. Then, when the cooked rice is frozen and thawed and warmed, the surface of the rice becomes sticky, or the rice grains adhere to each other and become dumpling-like. Therefore, as described above, in the case of "Freezing Mode", it is desirable to shorten the time of the boiling maintenance step S3 compared to the case of "Normal Mode". This can suppress excessive application of pressure and reduce the stickiness on the surface of the rice. Therefore, when the cooked rice is frozen and thawed and warmed, it is possible to suppress the surface of the rice from being sticky or the rice grains from adhering to each other and becoming dumpling-like.

[0049] Next, the control unit 80 executes the first pause step S4. The first pause step S4 is a step of temporarily lowering the temperature of the inner pot 10 between the boiling maintenance step S3 and the cooking completion step S5. In the first pause step S4, the control unit 80 operates the heating unit 40 at an output lower than that in the boiling maintenance step S3. Specifically, the control unit 80 sets the supply power to the induction heating coil to a third power (for example, 100 W) lower than the first power and the second power while maintaining the duty ratio of the current at the third duty ratio described above. As a result, the temperature of the inner pot 10 slightly decreases from the threshold temperature T described above.

[0050] Also, in the first pause step S4, the control unit 80 switches the valve 52 of the pressure regulating unit 50 from the fully closed state to the intermediate closed state. As a result, as shown in FIGS. 3 and 4, the pressure in the internal space 13 of the inner pot 10 in the first pause step S4 decreases from the maximum pressure to the intermediate pressure.

[0051] When a predetermined time has elapsed since the start of the first pause step S4, the control unit 80 ends the first pause step S4.

[0052] Next, the control unit 80 executes a cooking-up step S5. The cooking-up step S5 is a step of raising the temperature of the inner pot 10 again. In the cooking-up step S5, the control unit 80 operates the heating unit 40 at an output lower than that in the boiling-maintaining step S3 and higher than that in the first pause step S4. Specifically, the control unit 80 maintains the duty ratio of the current at the above-described third duty ratio, and sets the power supplied to the induction heating coil to a fourth power (for example, 700 to 1100 W) lower than the second power and higher than the third power. As a result, the temperature of the inner pot 10 rises again. As a result, the excess moisture on the surface of the rice in the inner pot 10 is reduced.

[0053] Further, in the cooking-up step S5, the control unit 80 maintains the valve 52 of the pressure regulating unit 50 in an intermediate throttle state. Thereby, as shown in FIGS. 3 and 4, the pressure in the internal space 13 of the inner pot 10 in the cooking-up step S5 is maintained at an intermediate pressure.

[0054] When the "normal mode" is selected, the control unit 80 sets the power supplied to the induction heating coil to 700 to 900 W in the cooking-up step S5. On the other hand, when the "freezing mode" is selected, the control unit 80 sets the power supplied to the induction heating coil to approximately 1100 W in the cooking-up step S5. That is, the power supplied to the induction heating coil in the cooking-up step S5 is higher when the "freezing mode" is selected than when the "normal mode" is selected. Thereby, the temperature of the inner pot 10 is rapidly raised.

[0055] When the temperature of the inner pot 10 input from the pot temperature sensor 61 reaches the threshold temperature T (for example, 110° C.) again, the control unit 80 ends the cooking-up step S5.

[0056] Similar to the above-described boiling maintenance step S3, also in this cooking step S5, when the "freezing mode" is selected, it is desirable that the threshold temperature T is lower than the threshold temperature T when the "normal mode" is selected. By doing so, the time of the cooking step S5 when the "freezing mode" is selected becomes shorter than the time of the cooking step S5 when the "normal mode" is selected. Thereby, over-pressurization after the rice is gelatinized can be further suppressed, and the stickiness on the surface of the rice can be reduced. Therefore, when the cooked rice is frozen and then thawed and warmed, it is possible to further suppress the surface of the rice from being sticky or the rice grains from adhering to each other and forming a dumpling shape.

[0057] When the "normal mode" is selected, next, the control unit 80 executes the second pause step S6. The second pause step S6 is a step of temporarily reducing the temperature of the inner pot 10 between the cooking step S5 and the second cooking step S7. In the second pause step S6, the control unit 80 operates the heating unit 40 at an output lower than that in the cooking step S5. Specifically, the control unit 80 maintains the duty ratio of the current at the above-described third duty ratio and reduces the power supplied to the induction heating coil from the fourth power to the third power. Thereby, the temperature of the inner pot 10 slightly decreases from the above-described threshold temperature T.

[0058] Also, in the second pause step S6, the control unit 80 switches the valve 52 of the pressure regulating unit 50 from the intermediate throttle state to the open state. Thereby, as shown in FIG. 3, the pressure in the internal space 13 of the inner pot 10 in the second pause step S6 decreases from the intermediate pressure to the atmospheric pressure.

[0059] When a predetermined time has elapsed since the start of the second pause step S6, the control unit 80 ends the second pause step S6.

[0060] When the "Normal Mode" is selected, next, the control unit 80 executes the double-cooking process S7. The double-cooking process S7 is a process of raising the temperature of the inner pot 10 and the pressure of the internal space 13 again. In the double-cooking process S7, the control unit 80 operates the heating unit 40 at an output lower than that in the boiling maintenance process S3 and higher than that in the second pause process S6. Specifically, the control unit 80 raises the supply power to the induction heating coil from the third power to the fourth power while maintaining the duty ratio of the current at the above-described third duty ratio. As a result, the temperature of the inner pot 10 rises again. As a result, the excess moisture on the surface of the rice in the inner pot 10 is further reduced.

[0061] Also, in the double-cooking process S7, the control unit 80 switches the valve 52 of the pressure regulating unit 50 from the open state to the intermediate throttle state. As a result, as shown in FIG. 3, the pressure in the internal space 13 of the inner pot 10 in the double-cooking process S7 rises again from the atmospheric pressure to the intermediate pressure.

[0062] When a predetermined time has elapsed since the start of the double-cooking process S7, the control unit 80 ends the double-cooking process S7.

[0063] On the other hand, when the "Freezing Mode" is selected, the control unit 80 does not execute the second pause process S6 and the double-cooking process S7. By omitting the double-cooking process S7, overpressure after the rice is gelatinized can be more suppressed. As a result, the stickiness on the surface of the rice can be reduced. Therefore, even when the cooked rice is frozen and then thawed and warmed, it is possible to more effectively prevent the surface of the rice from being sticky or the grains of rice from adhering to each other and forming a dumpling-like shape.

[0064] In the "Normal Mode", when the double-cooking process S7 is completed, or in the "Freezing Mode", when the cooking process S5 is completed, next, the control unit 80 executes the mashing process S8. The mashing process S8 is a process of maintaining the temperature of the inner pot 10 substantially constant to keep the state of the cooked rice. In the mashing process S8, the control unit 80 operates the heating unit 40 at an output lower than that in the cooking process S5 and the double-cooking process S7. Specifically, the control unit 80 maintains the duty ratio of the current at the above-described third duty ratio while reducing the power supplied to the induction heating coil from the fourth power to the third power. Thereby, the temperature of the inner pot 10 is maintained at a substantially constant temperature (for example, 80 to 90 °C).

[0065] Also, in the mashing process S8, the control unit 80 switches the valve 52 of the pressure regulating unit 50 from the intermediate throttle state to the open state. Thereby, as shown in FIGS. 3 and 4, the pressure in the internal space 13 of the inner pot 10 in the mashing process S8 decreases from the intermediate pressure to the atmospheric pressure.

[0066] As described above, in this rice cooker 1, two types of operation modes, "Normal Mode" and "Freezing Mode", can be selected. And the pressure in the internal space 13 of the inner pot 10 at the initial stage of the boiling maintenance process S3 when the "Freezing Mode" is selected is made higher than the pressure in the internal space 13 of the inner pot 10 at the initial stage of the boiling maintenance process S3 when the "Normal Mode" is selected. Thereby, the moisture content inside the rice cooked in the "Freezing Mode" can be increased. Therefore, even when the rice cooked in the "Freezing Mode" is frozen and then thawed and warmed, sufficient moisture can be retained inside the rice.

[0067] Also, in this rice cooker 1, the pressure in the internal space 13 of the inner pot 10 in the temperature rising process S2 when the "Freezing Mode" is selected is made higher than the pressure in the internal space 13 of the inner pot 10 in the temperature rising process S2 when the "Normal Mode" is selected. Thereby, the moisture content inside the rice cooked in the "Freezing Mode" can be increased even more.

[0068] In addition, in this rice cooker 1, the time of the boiling maintenance step S3 when the "freezing mode" is selected is shorter than the time of the boiling maintenance step S3 when the "normal mode" is selected. Thereby, overpressure after the rice is gelatinized can be suppressed, and the stickiness on the surface of the rice can be reduced. Therefore, when the rice cooked in the "freezing mode" is frozen and then thawed and warmed, it is possible to suppress the surface of the rice from being sticky or the rice grains from adhering to each other to form a dumpling shape.

[0069] In addition, in this rice cooker 1, the time of the cooking completion step S5 when the "freezing mode" is selected is shorter than the time of the cooking completion step S5 when the "normal mode" is selected. Thereby, overpressure after the rice is gelatinized can be further suppressed, and the stickiness on the surface of the rice can be further reduced. Therefore, when the rice cooked in the "freezing mode" is frozen and then thawed and warmed, it is possible to further suppress the surface of the rice from being sticky or the rice grains from adhering to each other to form a dumpling shape.

[0070] In addition, in this rice cooker 1, when the "freezing mode" is selected, the double cooking step S7 is not executed. Thereby, overpressure after the rice is gelatinized can be further suppressed, and the stickiness on the surface of the rice can be further reduced. Therefore, when the rice cooked in the "freezing mode" is frozen and then thawed and warmed, it is possible to further suppress the surface of the rice from being sticky or the rice grains from adhering to each other to form a dumpling shape.

[0071] <3. Modification Example> As described above, an embodiment of the present invention has been described, but the present invention is not limited to the above embodiment.

[0072] <3-1. First Modification Example> In the above embodiment, when the "freezing mode" is selected, the double cooking step S7 is not executed. However, even when the "freezing mode" is selected, the double cooking step S7 may be executed. That is, the double cooking step S7 may be executed in any of the operation modes of the "normal mode" and the "freezing mode".

[0073] However, when the "freezing mode" is selected, it is desirable that the time of the second cooking step S7 be shorter than the time of the second cooking step S7 when the "normal mode" is selected. Thereby, while executing the second cooking step S7, overpressure can be suppressed in the "freezing mode". Therefore, compared with the case where the second cooking step S7 is executed for the same time as in the "normal mode", the stickiness on the surface of the rice can be reduced.

[0074] Also, when the "freezing mode" is selected, in the second cooking step S7, it is not necessary to raise the pressure in the internal space 13 of the inner pot 10 again. That is, when the "freezing mode" is selected, in the second cooking step S7, only the temperature of the inner pot 10 may be raised again without raising the pressure in the internal space 13 of the inner pot 10. By doing so, overpressure after the rice is gelatinized can be further suppressed, and the stickiness on the surface of the rice can be further reduced. Therefore, when the rice cooked in the "freezing mode" is frozen and then thawed and warmed, it is possible to further suppress the surface of the rice from being sticky or the rice grains from adhering to each other and forming a dumpling shape.

[0075] <3-2. Second Modification Example> In the above embodiment, the valve 52 of the pressure regulating unit 50 switches between three stages: an open state, an intermediate throttle state, and a maximum throttle state. However, the valve 52 of the pressure regulating unit 50 may be capable of steplessly adjusting the opening degree. Further, the control unit 80 may realize the pressure changes in FIGS. 3 and 4 by performing feedback control on the opening degree of the pressure regulating unit 50 based on the measured value of the pressure sensor 70.

[0076] <3-3. Other Modification Examples> Also, in the above embodiment, the rice cooker 1, which is an example of a cooker, has been described. However, the cooker of the present invention may be one that heats and cooks ingredients other than rice.

[0077] In addition, the configuration of the cooker, the procedure of the cooking operation, the temperature change waveform, the pressure change waveform, and the supply power change waveform may be appropriately changed without departing from the gist of the present invention. Further, each element appearing in the above-described embodiments and modifications may be appropriately combined within a range where no contradiction occurs.

Explanation of Signs

[0078] 1 Rice cooker (cooker) 10 Inner pot 13 Internal space 20 Main body 21 Receiving recess 22 Hinge 30 Lid 40 Heating unit 50 Pressure regulating unit 51 Flow path 52 Valve 61 Pot temperature sensor 62 Lid temperature sensor 70 Pressure sensor 80 Control unit 90 Operation unit S1 Preheating process S2 Heating-up process S3 Boiling maintenance process S4 First rest process S5 Cooking completion process S6 Second rest process S7 Second cooking process S8 Levelling process

Claims

1. A cooker for cooking food by heating, comprising: An inner pot capable of containing the food and water; A main body on which the inner pot is set; A lid that covers the upper part of the main body to seal the internal space of the inner pot; A heating part for heating the inner pot; A pressure regulating part for adjusting the pressure of the internal space; A control part for controlling the heating part and the pressure regulating part; The control part can select two operation modes: a normal mode and a freezing mode. The control part: Performs a temperature rising process of raising the temperature of the inner pot to the boiling temperature, and After the temperature rising process, performs a boiling maintaining process of maintaining the temperature of the inner pot at the boiling temperature. When the freezing mode is selected, the pressure of the internal space at the initial stage of the boiling maintaining process is higher than the pressure of the internal space at the initial stage of the boiling maintaining process when the normal mode is selected. A cooker.

2. The cooker according to claim 1, wherein when the freezing mode is selected, the pressure of the internal space in the temperature rising process is higher than the pressure of the internal space in the temperature rising process when the normal mode is selected. A cooker.

3. The cooker according to claim 1 or claim 2, wherein when the freezing mode is selected, the time of the boiling maintaining process is shorter than the time of the boiling maintaining process when the normal mode is selected. A cooker.

4. The cooker according to any one of claims 1 to 3, wherein the control part further performs a cooking-up process of raising the temperature of the inner pot again while maintaining the pressure of the internal space higher than the atmospheric pressure after the boiling maintaining process. When the freezing mode is selected, the time of the cooking-up process is shorter than the time of the cooking-up process when the normal mode is selected. A cooker.

5. The cooker according to claim 4, wherein the control part further performs a second cooking process of raising the temperature of the inner pot and the pressure of the internal space again after the cooking-up process. When the freezing mode is selected, the time of the second cooking process is shorter than the time of the second cooking process when the normal mode is selected. A cooker.

6. The cooker according to claim 4, wherein when the normal mode is selected, the control part further performs a second cooking process of raising the temperature of the inner pot and the pressure of the internal space again after the cooking-up process, and when the freezing mode is selected, the control part does not perform the second cooking process. A cooker.

7. The cooker according to claim 4, wherein the control part: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A double-boiling process of raising the temperature of the inner pot again after the cooking process is further executed, when the normal mode is selected, in the double-boiling process, the pressure in the internal space is raised again, when the freezing mode is selected, in the double-boiling process, the pressure in the internal space is not raised again, the time of the double-boiling process when the freezing mode is selected is shorter than the time of the double-boiling process when the normal mode is selected, a cooker.

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