JP5338942B2 - Electric rice cooker - Google Patents

Description

  The present invention relates to an electric rice cooker, and more specifically, an electromagnetic equipped with an inner pot made of an earthen pot having a characteristic that thermal conductivity is not very good and heat storage is excellent and the temperature does not drop easily even when the heating output is stopped. The present invention relates to an induction type electric rice cooker.

  As a well-known electric rice cooker, a rice cooker body configured to detachably accommodate a metal inner pot, and an inner peripheral surface of the rice cooker body and the inner pot There is a thing equipped with a protective frame that supports when the container is housed, and an electromagnetic induction coil that generates electromagnetic induction in the inner pot. The thing cooked up is proposed (refer patent document 1).

  In recent years, in order to improve the cooking of rice, the inner pot consists of an earthen pot that has extremely low thermal conductivity and excellent heat storage properties, and does not easily drop in temperature even when heating output is stopped. Attempts have been made to use inner pots. In this case, since the inner pot itself does not generate heat due to electromagnetic induction, an induction heating element is disposed at the bottom of the inner pot and in the vicinity of the bottom (for example, a curved portion between the bottom and the side wall), and the induction heating element is The inner pot is heated by generating heat by the magnetic field generated from the induction coil (see Patent Document 2).

Japanese Patent Application Laid-Open No. 11-4758.

Japanese Patent Application Laid-Open No. 2004-141456.

  By the way, in the case of the electric rice cooker currently disclosed by patent document 1, it is cooked from the place where the inner pot is comprised with the metal material (especially metal material excellent in thermal conductivity) to the cooking temperature at a stretch with high output. However, since the temperature of the entire inner pot rises almost uniformly, it is difficult to cause local burning and the like, and it is possible to cook almost good rice.

  However, in the case of the electric rice cooker disclosed by patent document 2, since the inner pot which consists of earthen pots is used, it has the characteristic that heat conductivity is not very good. In the case of an electric rice cooker using an inner pot having such characteristics, if it is cooked by the same method as the electric rice cooker disclosed in Patent Document 1, local scoring will occur and good results will be obtained. There is a problem that can not be. Moreover, in the case of the inner pot which consists of such a clay pot, since it has the characteristic that it is hard to cool once heated (that is, it is excellent in heat storage property), the output to the rice cooking heating means is stopped. However, the temperature does not easily drop.

  The invention of the present application was made in view of the above points, and in an electric rice cooker using an inner pot made of a clay pot, it can prevent local burning while saving power consumption, and can cook delicious rice. The purpose is to be.

  In the present invention, as a first means for solving the above-mentioned problems, it is an inner pot that contains water and rice, has an extremely poor thermal conductivity and is excellent in heat storage, and is easy even if heating output is stopped. An inner pot composed of an earthen pot that does not drop in temperature, a rice cooker body that accommodates the inner pot in a removable manner, a lid that covers the upper opening of the rice cooker body so as to be openable and closable, and the inner pot is heated. Rice cooker heating means, a center sensor that detects the temperature of the bottom of the inner pot, and a lid sensor that is provided on the lid and detects the vapor temperature, and after the boiling detection, the rice cooking heating A cooking means for repeating ON heating to energize the means and regenerative heating without energizing the rice cooking heating means, and the cooking means has an OFF time during which the rice cooking heating means is not energized. The lower limit temperature at which the rice cooking heating means is turned on and the upper limit temperature at which it is turned off are set so as to be longer than the ON time for energizing the heating means, so that local burn can be prevented while saving power consumption. Yes.

  By comprising as mentioned above, ON heating which supplies electricity to a rice cooking heating means by the cooking means after boiling detection, and thermal storage heating which does not supply electricity to a rice cooking heating means will be repeated. As a result, the rice in the inner pot will not burn locally. And if the temperature of the rice in an inner pot falls, it will become possible to maintain high temperature by repeating the heating for a fixed time. By doing in this way, rice which has sweetness and has little cooking unevenness can be cooked. Moreover, since the OFF time can be determined by setting the lower limit temperature at which the rice cooking means is turned ON and the upper limit temperature at which it is turned OFF so that the OFF time becomes longer than the ON time. Setting is easy. As a result, even if it is an electric rice cooker using an earthen pot as an inner pot that has a characteristic that thermal conductivity is not very good and heat storage is excellent, and even if heating output is stopped, the temperature does not drop easily. Local burns can be prevented while saving.

  According to the first means of the present invention, it is an inner pot that contains water and rice, has a very low thermal conductivity, is excellent in heat storage, and does not easily drop in temperature even when heating output is stopped. An inner pot composed of an earthen pot, a rice cooker body that accommodates the inner pot so that it can be removed, a lid that covers the upper opening of the rice cooker body so as to be openable and closable, and a rice cooking heating means that heats the inner pot, In an electric rice cooker provided with a center sensor for detecting the temperature of the bottom of the inner pot and a lid sensor for detecting the steam temperature provided on the lid body, ON heating for energizing the rice cooking heating means after detection of boiling And a rice cooker heating means that repeats heat storage heating that does not energize, and ON heating that energizes the rice cooker heating means by the cooker after boiling detection and heat storage heating that does not energize the rice cooker heating means. Is repeated Since the rice in the inner pot is not burned locally, the temperature of the rice in the inner pot drops, and when the temperature of the rice in the inner pot drops, the heating is repeated for a certain period of time to maintain the high temperature. This has the effect of being able to cook rice that is sweet and has little uneven cooking. Moreover, since the OFF time can be determined by setting the lower limit temperature at which the rice cooking means is turned ON and the upper limit temperature at which it is turned OFF so that the OFF time becomes longer than the ON time. Even if it is an electric rice cooker using an earthen pot as an inner pot that has the characteristics that the setting becomes easy, the thermal conductivity is not very good, the heat storage property is excellent, and the temperature does not drop easily even if the heating output is stopped. There is an effect that local burning can be prevented while saving consumption.

  In the electric rice cooker according to the embodiment of the present invention, as shown in FIG. 1, for example, a clay pot is adopted as the inner pot 3 for containing rice and water, and the outer peripheral surface of the bottom wall portion 3 a and the bottom wall On the curved surface from the portion 3a to the side wall portion 3b surface, first and second induction heating elements G1, G2 made of metal, such as silver paste, capable of self-heating by the eddy current induced inside. Are attached individually.

  That is, this electric rice cooker has an inner pot 3 having the same configuration, a dish-shaped bottom wall portion 4 made of a lower side synthetic resin and an upper side cylindrical shape formed so that the inner pot 3 can be arbitrarily set. An inner case (protective frame) 46 composed of a side wall 6, a bottomed cylindrical outer case 1 that is an outer casing for holding the inner case 46, and the outer case 1 and the inner case 46 are integrally formed. It is comprised from the lid unit (lid) 2 provided in the upper part of the cooked rice cooker main body so that opening and closing is possible.

  A coil cover 93 is provided on the lower side of the bottom wall portion (bottom portion) 4a of the inner case 4, the ferrite core 7 is disposed at the lower portion thereof, and the bottom wall portion 3a of the inner pot 3 is disposed at the upper portion thereof. Corresponding to the positions of the induction heating elements G1 and G2 on the lower surface side and the side curved surface side, there are provided first and second sets of work coils C1 and C2 in which litz wires are wound concentrically. Thus, when energized, eddy currents are induced in the first and second induction heating elements G1, G2 of the inner pot 3 to indirectly heat the inner pot 3. The first and second work coils C1, C2 are connected to each other in series, for example (therefore, simply shown as the work coil C in the following description of the operation and the control circuit diagram of FIG. 3).

  The dish-shaped bottom wall portion 4 of the inner case 46 has a sensor portion fitting port of the center sensor CS formed at the center of the bottom surface portion 4a, and a donut-shaped heat shield on the outer peripheral side upper surface of the sensor portion fitting port. A plate 50 is provided. Further, a flange-like step portion 4c projecting outward in the predetermined width radial direction is provided on the upper end side of the outer peripheral side surface portion 4b, and the lower end 6b side of the upper side tubular side wall portion 6 is provided on the step portion 4c portion. The engagement is placed.

  On the other hand, the upper end 6 a of the upper cylindrical side wall 6 is connected and fixed to the shoulder member 11 at the upper end of the rice cooker main body via the inner frame member 9.

  One end of each of the first and second work coils C1, C2 is, for example, as shown in the control circuit diagram of FIG. 3, and the other end is an IGBT (power) via the rectifier circuit 35 and the smoothing circuit 36. Transistor) 37 is connected to the collector of each.

  Further, on the outer periphery of the upper cylindrical side wall portion 6 of the inner case 46, a heat retaining heater H1 made of, for example, a code heater or the like that functions as a heating means during rice cooking and heat insulation is provided. The whole inner pot 3 is heated effectively and uniformly. A side temperature sensor S3 composed of a thermistor for detecting the temperature of the temperature maintaining heater H1 is provided in the temperature maintaining heater H1.

  Then, by appropriately driving and controlling them with a microcomputer control unit as in the control circuit of FIG. 3, for example, an appropriate rice cooking function and a heat retaining function can be realized.

  By the way, in the case of this embodiment, for example, as shown in FIG. 1, the inner peripheral surface of the inner case 46 and the inner pot 3 composed of the dish-like lower side bottom wall 4 and the cylindrical upper side wall 6. Gap 5a-5g which forms the ventilation path which extends from the bottom side to the side upper part is provided between the outer peripheral surfaces.

  The gaps 5a to 5g are wide at the outer peripheral portion 5a of the inner center sensor CS of the donut plate-shaped heat shield 50, and are narrow at the portion 5b between the heat shield 50 and the bottom wall 3a of the inner pan 3, In the installation convex portions 31, 31, 31 portion 5c on the outer periphery of the bottom wall portion 3a of the inner pot 3, it is formed in a flat ring-shaped concave groove portion, and further, a curved portion extending from the bottom wall portion 3a of the inner pot 3 to the side wall portion 3b. The portion 5e gradually widens from a narrow state and reaches a lower portion of the side wall portion 3b that is straight in the vertical direction. The portion 5e is the largest and forms a hot air retaining space having a large cross-sectional area.

  And in the part 5f straight in the up-down direction from the lower part of the side wall part 3b of the inner pot 3 to the shoulder opening edge 3c, the upper side wall part 6 of the inner case 46 and the side wall of the inner pot 3 The rice cooker body and the lid unit 2 are formed in a narrow gap where the portion 3b is close to each other, and eventually through a wide gap 5g between the shoulder member 11 on the outer case 1 side and the opening edge 3c of the inner pot 3 It is open to the outside through the gap between.

  On the other hand, in the present embodiment, a fan 17 (see FIG. 3) is provided between the first work coil C1 as the electromagnetic induction heating means opposed in the vertical direction and the bottom member 1b of the outer case 1. The first and second wind inlets for introducing the wind from the fan 17 into the air passage between the inner case 46 and the inner pot 3 in the lower side dish-shaped bottom wall 4 of the inner case 46. (Not shown) is provided between the inner case 46 and the inner pot 3 after cooling the first work coil C1 with the wind from the fan 17 through the first and second wind inlets. It is made to raise to the whole side part outer peripheral side from the bottom part side. Reference numeral 93 is a coil cover that supports the first and second work coils C1, C2, and 94 is a support member such as a coil cover.

  On the other hand, reference numeral 2 denotes a lid unit. The lid unit 2 comprises an outer cover 12 made of a synthetic resin that constitutes an outer peripheral surface of the lid unit 2 and a pressure adjusting pipe 15 at the center, and is fitted inside the outer cover 12. A synthetic resin inner frame 13 provided integrally, a packing 14a and a metal heat radiating plate 16a in an inner opening of the inner frame 13, and a lid heater H2 provided on the upper surface of the heat radiating plate 16a; The lid sensor S4 comprises a thermistor for detecting the temperature of the heat radiating plate 16a, and a metal inner lid 16b provided below the heat radiating plate 16a. Further, packings 14a and 14b are respectively provided below the outer peripheral edge of the heat radiating plate 16a and below the outer peripheral edge of the inner lid 16b. The inner lid 16b is connected to the opening edge of the inner pot 3 via the packing 14b. It is made to contact the upper surface part of the part 3c. 15a is a pressure regulating valve in the pressure regulating pipe 15, 15b is a lower cap thereof, and 15c is a pressure regulating ball.

  The lid unit 2 is rotatably attached to the shoulder member 11 via a hinge mechanism 8 on the rear end side of the upper part of the outer case 1, and a predetermined portion of the lid unit 2 is disposed on the open end side. A lock mechanism 10 is provided that engages the position and regulates the opening and closing of the lid unit 2 in the vertical direction.

  On the other hand, the above-mentioned rice cooking, timer reservation for the heat retention function, selection of rice cooking and heat retention menu, operation settings such as heating amount, heating pattern, heat retention temperature, heat retention time, heat retention OFF control mode, etc. corresponding to each menu are related to the electric rice cooking This is performed by the user via various input switch groups 22a to 22i of the operation panel 20 as shown in FIG. The second work coils C1, C2, the heat retaining heater H1, and the lid heater H2 are appropriately controlled.

  The switches 22a to 22i of the operation panel 20 are, for example, a rice cooking switch 22a (ON display portion 23a), a timer reservation switch 22b (ON display portion 23c), a cancel switch 22c, a heat retention switch 22d (ON display portion 23b), and a reheating switch. 22e, a menu selection switch 22f, an hour switch 22g, a minute switch 22h, and a heat retention OFF control mode selection switch 22i (ON display portion 23d).

  In addition, at the center of the operation panel 20, there is a liquid crystal display unit 21 for displaying each menu of rice cooking and heat retention, a set heat retention temperature, a set heat retention time, a current time, a remaining time until the completion of rice cooking, and other necessary items. Is provided.

  In the space behind the operation panel 20 in the outer case 1, an operation board and a microcomputer board (not shown) are installed in an inclined state.

  Further, on the front side of the inner case 4 (see FIG. 1), for example, as shown in FIG. 3, the first and second work coils C1, C2, the heat retaining heater H1, the lid heater H2, etc. are driven and controlled. A power supply board (not shown) provided with the IGBT 37, the heat retaining heater drive circuit 33, the lid heater drive circuit 24, the rectifier circuit 35 including a diode bridge for power supply voltage rectification, the smoothing circuit 36, the microcomputer control unit 32, etc. It is installed upright.

  The outer case 1 includes, for example, a cylindrical cover member 1a formed of a metal member in the vertical direction, a synthetic resin shoulder member 11 coupled to the upper end of the cover member 1a, and the cover member 1a. The bottom member 1b is made of a synthetic resin and is integrated with the lower end portion, and a heat insulating and ventilating space portion having a predetermined width is formed between the bottom wall portion 4 of the inner case 46 and a bottomed surface as a whole. It is comprised by the cylindrical body.

  Furthermore, a center sensor fitting opening (center sensor storage space) penetrating concentrically in the vertical direction as described above is formed at the center of the bottom-side dish-shaped bottom wall 4 of the inner case 46. A center provided with an inner pot temperature detection sensor S1 and an inner pot detection switch S2 comprising a thermistor in a state in which the center sensor can be moved up and down in the center sensor storage space and is always upwardly biased by a coil spring. A sensor CS is provided.

  Therefore, in this configuration, at the time of rice cooking, the inner pot 3 is moved from the bottom wall portion 3a to the side wall portion 3b side by eddy current generated by driving the first and second sets of work coils C1 and C2. The provided first and second induction heating elements G1 and G2 generate heat to heat the portion from the bottom wall portion 3a to the side wall portion 3b of the inner pan 3, and the side wall portion of the inner pan 3 by the heat retaining heater H1. 3b is heated.

  Moreover, in the same state, the hot air from the fan 17 is supplied as described above to wrap the entire inner pot 3. As a result, for example, when the amount of cooked rice is large, the entire inner pot 3 is heated substantially uniformly and cooked efficiently without uneven heating. In addition, it is possible to prevent local heat concentration on the bottom wall portion 3a of the inner pot 3 in the state where moisture after the boiling process is lost, thereby preventing the occurrence of scorching.

  Next, at the time of heat insulation after cooking, the first and second work coils C1, C2 are turned off, while the heat insulation heater H1 and the heat radiating plate provided corresponding to the side wall 3b of the inner pot 3 are used. By driving the lid heater H2 provided at 16a, the entire inner wall 3b from the bottom wall 3a of the inner pot 3 and the upper part are uniformly heated with an appropriate heating amount, and the heat retaining power of the earthenware pot that does not cause condensation is obtained. Thermal insulation is achieved by using the remaining heat.

  By the way, the microcomputer control unit 32 of the microcomputer board P2 is provided with desired recognition means for judging the contents of the user's instruction inputted via the input switches 22a to 22i. Depending on the user's instructions, the desired rice cooking or heat retaining function, the heat retaining OFF function, the desired rice cooking (or heat retaining) menu, the predetermined heating pattern corresponding to the rice cooking or heat retaining menu is set, and the rice cooking heating control means Alternatively, the desired heat cooking control or heat retention OFF control is performed by appropriately operating the heat insulation heating control means and the heat insulation OFF control means.

  Therefore, the user can use the above input switches 22a to 22i to cook rice or keep warm, timer reservation, reservation time setting, white rice or brown rice, early cooking, rice porridge, sushi, cooked cooking, etc., normal warming mode or energy saving warming If the selected setting contents of various modes such as mode, heat insulation OFF mode, etc. are input, the corresponding function contents are automatically set and input to the setting unit such as rice cooking and heat insulation heating pattern via the recognition means in the microcomputer control unit 32 Thus, the corresponding rice cooking or heat insulation heating control and heat insulation OFF control are appropriately performed.

(Configuration of the rice cooker body side control circuit)
Next, FIG. 3 shows a rice cooker main body side rice cooker (or a heat control first and second work coils C1, C2 control, and a control circuit centered on a microcomputer control unit 32 for performing other controls. The structure of a part is shown.

  In the figure, reference numeral 32 denotes a rice cooker heating control means and a heat retention heating control means, an inner pot temperature determination means, an inner pot detection means, a buzzer notification means, etc. This is a control unit (CPU), and the microcomputer control unit 32 is mainly composed of a microcomputer. For example, the bottom part of the inner pot 3, each temperature detection circuit part on the side part, the temperature detection circuit part of the radiator plate 16a, and the work coil drive A control circuit unit, a set state detection circuit unit of the inner pot 3, an oscillation circuit unit, a reset circuit unit, a drive control circuit unit such as a heat retaining heater and a lid heater, a buzzer notification unit, and a power supply circuit unit are each configured. .

  First, the inner pan temperature detection sensor S1 of the center sensor CS portion on the bottom wall portion 3a side of the inner pan 3, the side temperature sensor S3 of the side portion 3b of the inner pan 3, and the lid sensor S4 of the lid 2 side radiator plate 16 are provided. In the temperature detection circuit 43 provided corresponding to the inner pot detection circuit 44 and the pot detection circuit 44 provided corresponding to the inner pot detection switch S2, the temperature detection signal of the bottom wall portion 3a of the inner pot 3 and the temperature of the side wall portion 3b are provided. The detection signal, the temperature detection signal of the radiator plate 16a on the lid 2 side, and the inner pot detection signal by the inner pot detection switch S2 are input.

  The work coil drive control circuit unit is formed by, for example, a pulse width modulation circuit 41, a synchronization trigger circuit 40, an IGBT drive circuit 42, an IGBT 37, and a resonance capacitor 38. Then, by controlling the pulse width modulation circuit 41 by the work coil drive control circuit unit of the microcomputer control unit 32, the output value and the output value of the work coil C (C1, C2) according to, for example, the rice cooking process. By appropriately changing the ON duty ratio (for example, n seconds / 16 seconds) in each, the heating temperature and heating pattern of the inner pot 3 in each step of the rice cooking process are appropriately variably controlled in consideration of the amount of rice cooking, and uniform Appropriate output control is realized to realize the boiled rice without any water absorption and uneven heating.

  Further, by controlling the warming heater driving circuit 33 and the lid heater driving circuit 24 by the warming heater driving control circuit unit and the lid heater driving control circuit unit of the microcomputer control unit 32, respectively, for example, the above-mentioned warming according to the warming or rice cooking process. By appropriately changing the output values of the heater H1 and the lid heater H2 and the ON duty ratio (for example, n seconds / 16 seconds) at the same output values, the heating temperature and heating of the inner pot 3 in each step of the heat retention or rice cooking process Appropriate output control for appropriately variably controlling the pattern in consideration of the actual amount of cooked rice is performed.

  Reference numerals 22a to 22i denote the various input switches of FIG. 3 described above. When necessary ones of the switches 22a to 22i are appropriately operated, the contents of the user instruction are recognized by the recognition means on the microcomputer control unit 32 side. The desired control means corresponding to the recognized content is appropriately operated to perform the desired control.

  And in the case of this embodiment, when the above-mentioned heat insulation OFF control mode selection switch 22i is pushed, after the completion of rice cooking, the heat insulation heating and the heat insulation display by the normal heat insulation duty ratio are not performed. From the bottom of the inner pan 3 where condensation is unlikely to occur while turning on and off the heat retaining heater H1 and lid heater H2 at 1/16 and 2/16, which have a larger OFF period than the duty ratio to maintain balance. In addition, the temperature of the inner pot is gradually lowered while the temperature of the heat radiating plate 16a on the lid 2 side is high, and dew prevention control is performed to lower the temperature of the rice to a predetermined temperature of 50 ° C (or a predetermined time). Is done.

  3 is a flywheel diode of the IGBT 37, 35 is a power supply side rectifier circuit incorporating a diode bridge for driving the work coil inserted between the household AC power supply 30, and 36 is This is a smoothing circuit.

  Reference numeral 17 denotes the above-described fan, 34 denotes a drive circuit for the fan 17, and 21 denotes a liquid crystal display unit. In the case of this embodiment, the liquid crystal display unit 21 displays necessary items such as a desired menu and time corresponding to the ON operation of the input switches 22a to 22i. Is going to be made.

  In the control circuit of FIG. 3, the constant voltage power supply circuit to the microcomputer control unit 32 side is omitted in order to avoid complexity.

  Next, the flowchart of FIG. 4 shows the control flow in the rice cooking-heat retention process of the electric rice cooker concerning this Embodiment.

  First, in step S1, for example, when a predetermined rice cooking course is selected by operating the menu switch 22f and rice cooking is started by operating the rice cooking switch 22a, a water absorption process is executed in step S2. In this water absorption process, as shown in the time chart of FIG. 5, temperature adjustment is performed so that the work coils C1 and C2 are energized at an output of 60% and the detected temperature of the center sensor CS is 30 ° C. Temperature adjustment is performed by the heater H2 such that the detection temperature of the lid sensor S4 is 30 ° C., and water is absorbed at a low temperature for a certain period of time. The reason for doing this is because the poor heat conduction of the inner pot 3 made of a non-metallic material is taken into consideration, and the whole temperature is set to a constant temperature (for example, 30 ° C.) when water absorption is completed. At this time, the side heater H1 is not energized.

  In step S3, the first combined number determination (in other words, the first rice cooking amount determination) is performed near the end of the water absorption process. In this first total number determination, as shown in the time chart of FIG. 5, the work coils C1 and C2 are energized at an output of 80% and slightly heated (for example, the detection of the center sensor CS after a predetermined time). In the process where the temperature reaches 50 ° C., the total number is determined based on the integrated value of the OFF time in the ON / OFF control of the work coils C1, C2. In this case, due to the poor heat conduction of the inner pot 3 made of earthenware pot, the minimum amount Mmin from the point where the integrated value of the OFF time of the work coils C1, C2 cannot be much different except when the amount of rice cooking is minimum. And other numeration M are determined by two rank divisions (that is, rough numeration determination divided into at least two ranks).

  In step S4, one step of temperature increase is performed. In this temperature rising process, as shown in the time chart of FIG. 5, the work coils C1, C2 are energized with an output of 70% to 100%, and the side heater H1 is energized with a duty ratio of 8/16. The heating is started by increasing the electric power, and heating is performed until the boiling is detected by the lid sensor S4, or until the time limit of the internal monitoring timer elapses (in other words, the timer is up). At this time, the lid heater H2 is not energized.

  In the temperature rising process 1, the second combined number determination (in other words, the second rice cooking amount determination) is performed in step S5. In this second total number determination, the final number determination is performed by measuring the time of the section of one step of temperature increase. In this case, even if there is a poor heat conduction in the inner pot 3 made of an earthen pot since the temperature rise in the first temperature raising step can be greatly taken, the total amount other than the minimum amount Mmin determined in the first total number determination A total number determination for dividing the number M into at least two ranks is performed. For example, the amount of cooked rice is divided into at least three ranks such as Mmin, M1, M2, and M3 (M1 <M2 <M3).

  As described above, after rough ranking is performed by the first combined number determination, the second power supply is controlled while controlling the power supply amount to the work coils C1 and C2 based on the determination result by the first combined number determination. Since the final rice cooking amount determination is to be performed by the total number determination, it is possible to make an accurate rice cooking amount determination even when using the inner pot 3 made of a clay pot with poor thermal conductivity. It will be possible.

  In steps S6, S7, and S8, a temperature rise 2 step, a temperature rise 3 step, and a temperature rise 4 step are performed. In these temperature rising steps 2 to 4, the work coils C1 and C2 are energized with an output of 60% to 80%, and the side heater H1 is energized with a duty ratio of 8/16. Is heated to a sufficiently high temperature (for example, 120 ° C.). At this time, the lid heater H2 is not energized.

  In step S9, one step of cooking is performed. In this cooking process, as shown in the time chart of FIG. 5, the work coils C1, C2 are energized at an output of 60%, and the lid heater H2 and the side heater H1 are energized at a duty ratio of 8/16. Therefore, the electric power of the work coils C1, C2 is lowered to maintain boiling. The reason why the power of the work coils C1 and C2 can be lowered during the boiling maintenance is derived from the extremely good heat storage property of the inner pot 3 made of a clay pot.

  In step S10, two cooking steps are performed. In the two cooking steps, as shown in the time chart of FIG. 5, the outputs of the work coils C1, C2 are slightly raised to 70%, and the lid heater H2 and the side heater H1 are energized with a duty ratio of 6/16. The power of the work coils C1 and C2 is slightly increased to maintain the temperature above the boiling point.

  In step S11, 3 steps of cooking by the cooking means are performed. In the three cooking steps, as shown in the time chart of FIG. 5, the work coils C1 and C2 are energized with repetition of OFF and ON for a predetermined time, and the lid heater H2 and the side heater H1 have a duty ratio of 8. The current is energized at / 16, and boiling is maintained while preventing the rice from being burnt by intermittent energization of the work coils C1, C2. In other words, when the temperature of the rice is lowered, the heating is repeated for a certain time to maintain the high temperature. Such control is possible because the heat storage property of the inner pot 3 made of a clay pot is very good. If it does in this way, while the rice in the inner pot 3 will not burn locally, if the temperature of the rice in the inner pot 3 falls, heating for a fixed time will be repeated, and high temperature will be maintained. It is possible to cook rice that is sweet and has little uneven cooking.

  In step S12, an unevenness process is performed. In this unevenness process, as shown in the time chart of FIG. 5, the energization of the work coils C1, C2 is stopped, and the lid heater H2 and the side heater H1 are energized with a duty ratio of 8/16. Because the heat storage of the inner pot 3 made of earthenware pot is very good, even if the power to the work coils C1, C2 is stopped, the rice can be sufficiently uneven. is there.

  In step S13, a heat retaining step is performed. In this heat retaining step, the energization of the work coils C1, C2, the lid heater H2, and the side heater H1 is stopped. In addition, after the detected temperature of the center sensor CS is lowered to the heat retaining temperature, the heat retaining control similar to the conventional heat retaining control is executed.

  By the way, cooking may be performed by a method other than that described in the above embodiment.

  For example, when the inner pot 3 made of an earthen pot is used, the temperature rise of the center sensor CS is extremely delayed due to poor heat conduction, and quick temperature detection (cooking temperature, etc.) is hardly possible. Conventionally, it is not easy to detect cooking at temperature, so it is real that the heating is stopped with a timer according to the current total number judgment, but the heating stop with the timer has changed the balance between the amount of water and the amount of rice In this case, there was a problem that it was not possible to cook to the same hardness. Therefore, using the combined number determination result, the cooking timer and upper and lower cooking temperatures are set to detect cooking. Here, the timer time is set based on the combined number determination result.

  As shown in FIG. 6, when the upper limit temperature Tmax is exceeded before the timer expires, heating is stopped as cooking when the upper limit temperature Tmax is exceeded. Further, as shown in FIG. 7, if the lower limit temperature Tmin is not exceeded even when the upper limit of the timer is increased, heating is continued until the lower limit temperature Tmin is exceeded. Furthermore, as shown in FIG. 8, when the timer time is increased in a state where the lower limit temperature Tmin is not exceeded and the upper limit temperature Tmax is not exceeded, heating is stopped as cooking with the timer time-up. If it does in this way, while being able to respond to a soft and firm setting without a cost burden, even if the water amount is wrong, the stable cooking is obtained.

  In addition, the inner pot 3 made of earthenware has poor heat conduction, and the temperature around the heating elements G1 and G2 attached to the surface is high, but the temperature at the center of the bottom of the inner pot 3 does not rise in real time. If this is the case, correct temperature detection cannot be performed, and heating OFF by the work coils C1 and C2 will be delayed, leading to burnt rice.

  Therefore, as shown in FIG. 9, after the boiling detection, a control method is proposed in which heating by the work coils C1 and C2 is turned ON-0FF, a subtle temperature change is read, and cooking is detected at an appropriate timing. This control method will be described with reference to the flowchart shown in FIG.

In step S1, the cooking process is performed by performing heating control with electric power according to the combined number determination result. When it is confirmed in step S2 that boiling has been detected and it has been confirmed in step S3 that 3 minutes have passed (that is, the boiling state has been maintained for a predetermined time), in step S4, the work coil C1 is spaced at predetermined intervals. , C2 is ON-0FF controlled. With this ON-0FF control, the heating power is reduced and overrun is prevented. In step S5, it is determined whether or not the temperature of the inner pot 3 has decreased during the ON-0FF control. This determination is to detect the presence or absence of moisture in the inner pot 3. When water is present in the inner pot 3, the temperature of the inner pot quickly decreases when the work coils C1, C2 are turned off. From the point that the pot temperature is difficult to decrease (see FIG. 9), the presence or absence of moisture in the inner pot 3 is detected by the presence or absence of a decrease in the inner pot temperature.
While the affirmative determination is made in step S5 (that is, it is determined that there is a temperature drop), the above-described ON-0FF control is executed, but a negative determination is made in step S5 (that is, a determination that the temperature drop has disappeared) In step S6, it is determined that the food has been cooked, and the work coils C1, C2 are turned off. The reason is that even if the work coils C1 and C2 are turned off, if the temperature does not decrease, it is determined that the moisture in the inner pot 3 has run out, and the work coils C1 and C2 are quickly turned off to prevent scorching. This is because it is desirable. Even if it does in this way, in the case of the inner pot 3 which consists of earthen pots, since it is excellent in heat storage property, temperature rises enough by residual heat. Thereafter, the process shifts to the steaming control in step S7, and the control ends.

  In addition, it may be difficult to detect the cooking with the center sensor CS due to the poor heat conduction of the inner pot 3 made of earthen pot, but after the predetermined temperature has been reached with the lid sensor S4, the cooking is over a certain period of time. It can also be.

  In addition, since the amount of power required from the start of cooking to the start of cooking is constant to a certain extent after the lapse of the total number determination, it is cooked with the integrated power amount and rapid temperature change for each total number based on the total number determination. Detection may be performed. In addition, the correction by the initial water temperature and the ambient temperature is necessary.

  By the way, the inner pot 3 made of earthenware has good heat storage, so even if you don't set a high cooking detection temperature, it is only necessary to make sure that excess moisture can fly at a low temperature. Energy saving.

  Moreover, since the inner pot 3 made of earthenware has good heat storage, there is a big difference due to the difference between the control method and the inner pot made of other materials in the cooking process and the steaming process when the temperature of the inner pot has risen sufficiently. . Especially in the steaming process, the entire inner pot 3 is hot, and the energization amount to the side heater H1 and the lid heater H2 is set so as to wrap the inner pot 3 with the three sensors of the center sensor CS / side sensor S3 / lid sensor S4. It is preferable to determine. At this time, it is more preferable to control the side heater H1 and the lid heater H2 so as to maintain each sensor value when the process proceeds to the steaming step. In addition, it is more preferable to adjust the heating so that the inner pot 3 is wrapped around the three sensors at the same predetermined temperature when the process proceeds to the steaming step.

  The invention of the present application is not limited to the above-described embodiment, and it is needless to say that the design can be appropriately changed without departing from the gist of the invention.

It is a longitudinal cross-sectional view of the electric rice cooker concerning embodiment of this invention. It is an enlarged plan view of the operation panel part in the electric rice cooker concerning embodiment of this invention. It is a block diagram which shows the structure of the control circuit part of the electric rice cooker concerning embodiment of this invention. It is a flowchart which shows the control content in the rice cooking-heat retention process by the microcomputer control unit of the electric rice cooker concerning embodiment of this invention. It is a time chart which shows the control content in the rice cooking-heat retention process by the microcomputer control unit of the electric rice cooker concerning embodiment of this invention. It is a time chart which shows an example of the cooking detection in the electric rice cooker concerning embodiment of this invention. It is a time chart which shows another example of the cooking detection in the electric rice cooker concerning embodiment of this invention. It is a time chart which shows another example of the cooking detection in the electric rice cooker concerning embodiment of this invention. It is a time chart which shows the temperature change in the case of the cooking detection by the other method in the electric rice cooker concerning embodiment of this invention. It is a flowchart which shows the control content in the case of the cooking detection by the other method in the electric rice cooker concerning embodiment of this invention.

1 is the rice cooker body (outer case)
2 is a lid (lid unit)
3 is an inner pot 32 is a microcomputer control unit C1 to C2, C is a rice cooking heating means (first to second work coils)
H1 is a warming heater H2 is a lid heater CS is a center sensor S3 is a side sensor S4 is a lid sensor

Claims (1)

  An inner pot that contains water and rice, has an excellent thermal conductivity, has excellent heat storage characteristics, and does not easily drop in temperature even when heating output is stopped, and this inner pot A rice cooker body that can be removably accommodated, a lid that covers the upper opening of the rice cooker body so as to be openable and closable, a rice cooking heating means that heats the inner pot, and a center that detects the temperature of the bottom of the inner pot An electric rice cooker provided with a sensor and a lid sensor that is provided on the lid and detects a steam temperature, and after the boiling is detected, the rice cooking heating means is energized and the rice cooking heating means is energized The rice cooking means is provided such that the rice cooking heating means is repeatedly turned off, and the rice cooking heating means has an OFF time in which the rice cooking heating means is not energized longer than an ON time in which the rice cooking heating means is energized. Set the upper limit temperature to OFF and the lower limit temperature of the heat means turns ON, the electric rice cooker, characterized in that the adapted to prevent localized scorching while saving power consumption.

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