JP2011036397A - Electric rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save the consumption power as much as possible by avoiding temperature rise control when the lid has not been opened in a rice cooker which performs the temperature rise control whenever a specified period of time has passed in the heat insulating process. <P>SOLUTION: This electric rice cooker is equipped with a heat-insulation controlling means which controls the power feeding state to a heat-insulating/heating means in such a manner that the temperature of cooked rice may be kept at a previously set heat-insulating temperature after the completion of rice cooking, and at the same time, rises the temperature of the cooked rice after the specified period of time has passed during the heat-insulation control. The electric rice cooker is constituted in such a manner that no temperature rise control for raising the temperature of the cooked rice is performed when the lid of the rice cooker has not been opened during a period from the sensing of cooking completion to the heat-insulating process, and during the heat-insulating process. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  This invention relates to the electric rice cooker provided with the heat retention function after the completion of rice cooking in addition to the rice cooking function.

  In a recent electric rice cooker, a so-called rice cooker type is generally used in which, after the completion of rice cooking, the process proceeds to a heat insulation process as it is and heat insulation is performed at a predetermined heat retention temperature.

  However, in the case of such an electric rice cooker, various germs may increase with the passage of heat retention time, or decay may progress.

Therefore, in the conventional electric rice cooker, for example, as shown in the time chart of FIG. 9, after cooking, when the rice cooking is finished through the unevenness process, the process proceeds to the heat retaining process, and the inner pot such as a heater or a work coil By stopping energization of the heating means, the temperature of the rice is quickly lowered to the target set heat retention temperature Ts ₁ , and then the heat retention heater is energized to perform heat insulation heating control at the set heat retention temperature Ts ₁ .

  The control of the heat retaining heater in this heat retaining step is performed by turning the triac on and off by, for example, a microcomputer control unit. The microcomputer-type control unit has a target heat retention temperature set in advance by the user. When the temperature of the heat sensitive part of the center sensor is lower than the set temperature, the heat insulation heater is energized. Is kept constant (see FIG. 7).

Then, after the transition to the heat retention step, when a predetermined heat retention time t ₁ at which progress of spoilage due to germs is expected has elapsed, the above-described process is performed until the temperature of the rice reaches a temperature Tsh high enough to kill the germs. Energize the inner pot heating means, raise the temperature and sterilize.

Thereafter, when the heat retention time t ₂ longer than the elapsed time t ₁ further elapses, the same temperature increase control is performed again.

In this case, if necessary, the set value (maintenance temperature) of the heat insulation temperature itself is gradually increased to ΔT ₁ , ΔT ₂ ... As shown in FIG. A method of increasing the anti-corruption effect as the length increases is also adopted (see Patent Document 1 as an example).

  According to such a configuration, it is possible to suppress the progress of decay due to the growth of various germs and to maintain the heat retaining state for as long as possible.

JP 2002-209736 A

  However, in the case of the above configuration, the temperature rise control is performed uniformly without considering the actual state of invasion of various germs. For example, after the unevenness process, the lid of the rice cooker is kept at the set temperature keeping temperature. When the rice is opened or not opened, or even when the lid is opened, the temperature of the rice is higher than 80 ° C, such as during or after the end of the rice, and the invading bacteria are killed. The conditions are completely different from the case of, and when there is no risk of invasion of germs whose lid has not been opened, or when the lid is opened, at high temperatures when the germs will be killed, the temperature rise control is completely different from the other cases It is preferable to reduce the number of times and to save power consumption by not performing the operation or by limiting to only when a considerable heat retention time has elapsed.

  The present invention was made based on such circumstances, at least during the heat retention process after detecting the cooking and during the heat retention process, when the lid is not opened, the heat retention process described above. An object of the present invention is to provide an electric rice cooker in which wasteful power consumption is saved by not performing temperature rise control inside.

  In order to achieve the above object, the present invention is configured with the following problem solving means.

(1) The problem-solving means of the invention of claim 1 The problem-solving means of the present invention controls the state of energization to the heat-retaining and heating means so that the temperature of the rice is maintained at a predetermined heat-retaining temperature after the completion of rice cooking. In addition, when a predetermined time has elapsed during the heat retention control, in the electric rice cooker provided with a heat retention control means for raising the temperature of the rice, at least during the heat retention process after detecting the cooking and When the lid of the rice cooker is not opened during the heat retaining step, the temperature raising control for raising the temperature of the rice is not performed.

  According to such a configuration, as described above, when the lid of the rice cooker is not opened after detection of cooking, when there is no invasion of germs, the temperature rise control for sterilization is omitted, and the normal heat retention control is performed. Since it is continued, power consumption can be saved accordingly.

(2) The problem-solving means of the invention of claim 2 The problem-solving means of this invention is the structure of the problem-solving means of the invention of claim 1 above, even if the rice cooker lid is opened, When the temperature is higher than a predetermined high temperature at which invading bacteria can be killed, the temperature rise control is not performed.

  According to such a configuration, as described above, even if the lid of the rice cooker is opened and miscellaneous germs have invaded, after the cooking has been detected, it is in the middle of shifting to the set heat retention temperature through the unevenness process. When the temperature of the rice is in a high temperature state that can kill germs, the temperature increase control for sterilization described above is omitted, and normal heat retention control is continued, thus saving power consumption accordingly. be able to.

(3) Problem solving means of the invention of claim 3 The problem solving means of the present invention is the configuration of the problem solving means of the invention of claim 1 or 2, further comprising temperature detection means for detecting the temperature of the inner pot, When the temperature of the inner pot detected by the temperature detecting means is decreased by a predetermined value or more, it is detected that the lid of the rice cooker is opened.

  According to such a configuration, it is determined that the lid of the rice cooker has been opened when the temperature of the inner pot detected by the temperature detecting means has fallen by a predetermined value or more, and the necessary temperature increase control is performed to enable sterilization. Can do.

(4) Problem solving means of the invention of claim 4 The problem solving means of the present invention is the configuration of the problem solving means of the invention of claim 1, 2 or 3, wherein the lid is opened and closed in the heat retention control state at the set heat retention temperature. The state detection is performed based on the temperature decrease range obtained by correcting the fluctuation range of the detection temperature when the heating amount of the heating means is increased or decreased based on the set heat retention temperature. It is.

  Control of the heat retaining heating means in the heat retaining step is performed by turning the triac on and off by, for example, a microcomputer control unit. The microcomputer-type control unit has a target heat retention temperature set in advance by the user. When the temperature detected by the temperature detection means is lower than the set temperature, the heat insulation heating means is energized. The heat insulation temperature is kept constant.

  In other words, this control is a two-position ON-OFF control in terms of the control system, and naturally involves an overshoot of a predetermined width in two directions between the two positions.

  Accordingly, even when the temperature detection means detects a temperature drop of a predetermined width or more to detect opening / closing of the lid, the detection is performed in consideration of the fluctuation range due to the overshoot. Thereby, it is possible to accurately detect the lid open / closed state with the fluctuation range offset.

  As a result of the above, according to the present invention, it is possible to prevent the proliferation of germs and to reduce the power consumption during the heat retention by reducing the temperature rise control.

It is sectional drawing which shows the whole structure of the electric rice cooker main body which concerns on embodiment of this invention. It is a front view of the operation panel part centering on the liquid crystal display panel of the electric rice cooker. It is a block diagram which shows the whole structure of the control circuit part of the electric rice cooker. It is a flowchart which shows the content of the heat retention control from the cooking detection of the electric rice cooker. It is a time chart which shows the content of the heat retention control accompanying the temperature rising control of the electric rice cooker. It is a time chart which shows the content of the heat retention control which does not accompany the temperature rising control of the electric rice cooker. It is a time chart which shows the hunting state at the time of the heat retention temperature adjustment control in the heat retention control of the electric rice cooker (at the time of setting heat retention temperature 60 degreeC maintenance control). It is a time chart which shows the content of the heat retention control of the electric rice cooker which concerns on Embodiment 2 of this invention. It is a time chart which shows the content of the heat retention control of the conventional electric rice cooker.

  1-7 has each shown the structure and effect | action of the whole electric rice cooker which concerns on embodiment of this invention, and the principal part.

<Basic configuration>
First, as the electric rice cooker in the embodiment of the present invention, for example, an inner pot (rice cooker) 3 made of a magnetic metal plate capable of electromagnetic induction is adopted, while heating means during rice cooking for the inner pot 3 is adopted. As a side part 3a and the center side of the bottom wall 3a of the inner pot 3 so as to wrap substantially the entire side wall 3b from the bottom wall 3a of the inner pot 3 through the inner case 4 made of synthetic resin Are provided with two sets of work coils C ₁ and C ₂ , and as a heating means for keeping the inner pot 3 warm, a heat retaining heater H ₁ corresponding to the entire circumference of the side wall 3 b of the inner pot 3, A shoulder heater H ₂ corresponding to the entire circumference of the opening edge 3 c is provided.

  And appropriate rice cooking / cooking function and a heat retention function can be implement | achieved now by carrying out drive control appropriately by the microcomputer control unit 32 by the side of the control board 5A near the inner pot 3 mentioned later.

  On the other hand, timer setting according to those functions, rice cooking and heat insulation menu, selection of heat cooking menu, selection setting operation such as heating amount, heating pattern, heat insulation temperature, heat insulation time corresponding to each menu, the electric rice cooker concerned When the user performs various input switch groups (operation key groups) 22a to 22i provided on the front side operation panel unit 20 of the main body, and the selection setting contents are stored in the memory unit of the microcomputer control unit 32. At the same time, it is displayed on the liquid crystal display unit 21 of the operation panel unit 20.

Then, the selection setting information is supplied to the microcomputer control unit 32 on the control board 5A side through the interface circuit, and finally the work coils C ₁ and C ₂ and the heat retaining heater H ₁ according to the information content. The shoulder heater H ₂ is controlled.

  The liquid crystal display unit 21 includes, for example, rice cooking, cooking (bread fermentation / baking), heat retention menu, set heat retention temperature, set heat retention time, heat retention elapsed time (guaranteed time), current time, timer rice cooking reservation time, Completion of cooking, the remaining time until completion of cooking, and other various necessary items (see FIGS. 2 and 3) are displayed.

<Detailed configuration of the rice cooker body>
The rice cooker body of the electric rice cooker is, for example, as shown in FIG. 1, an inner pot (rice cooker or heat insulation container) made of a magnetic metal plate such as a stainless steel plate capable of self-heating by an eddy current induced therein. 3, a synthetic resin bottomed cylindrical inner case (protective frame) 4 formed so that the inner pot 3 can be arbitrarily set, and a bottomed cylinder which is an outer casing for holding the inner case 4 The outer case 1 and a lid unit 2 that can be opened and closed at the top of a rice cooker body formed by integrating the outer case 1 and the inner case 4 are formed.

A coil base 7 is provided on the lower side of the bottom wall portion 4a of the inner case 4, and the center and side portions of the bottom wall portion 3a of the inner pot 3 are positioned above the coil base 7 via a ferrite core. The two sets of work coils C ₁ and C ₂ each having a litz wire wound concentrically in correspondence with each other wrap around substantially the whole from the center portion of the bottom wall portion 3a of the inner pot 3 to the side wall portion 3b. As a result, an eddy current is induced in substantially the entire inner pot 3 when energized, and the whole is heated substantially uniformly. The work coils C ₁ and C ₂ are connected in series to each other (therefore, simply shown as the work coil C in the following description of operation and the control circuit diagram of FIG. 4).

  For example, as shown in the control circuit diagram of FIG. 3, one end thereof is connected to a power supply line via a rectifier circuit 35 and a smoothing circuit 36, and the other end is connected to a collector of an IGBT (power transistor) 37, respectively.

Further, the side wall portion of the inner case 4 is provided with a heat retaining heater H ₁ that functions as a heating means at the time of heat insulation, and the whole inner pot 3 is effectively and uniformly heated at the time of heat insulation. Yes.

Further, on the front side of the inner case 4, the IGBT 37 and the heater driving circuit 33 for driving and controlling the work coils C ₁ and C ₂ , the heat retaining heater H ₁ , the shoulder heater H _{2 and the} like as shown in FIG. , 45, a control board 5A including a rectifier circuit 35 including a diode bridge for power supply voltage rectification, a smoothing circuit 36, a microcomputer control unit 32, and the like is provided extending in the vertical direction.

  Under the control board 5A, for example, a heat sink 82 for heat dissipation is provided in contact with the IGBT 37, and a cooling fan 8 is provided under the heat sink 82. The cooling fan 8 causes the air sucked from the air suction grille 81 formed at the bottom of the outer case 1 to flow to the outer periphery of the inner case 4 via the heat sink 82 and the control board 5A to cool the necessary heat generating part. I do.

  The outer case 1 includes, for example, a vertical cover member 1a formed of a synthetic resin material, a synthetic resin shoulder member 11 coupled to an upper end portion of the cover member 1a, and the cover member 1a. And a bottom member 1b made of a synthetic resin integrated with the lower end portion of the inner casing 4 and having a heat insulation and ventilation space portion with a predetermined width between the bottom wall portion 4a of the inner case 4 as a whole. It is comprised by the cylindrical body. An operation panel unit 20 as shown in FIG. 2 is provided above the front surface of the outer case 1, for example.

  A liquid crystal display unit 21 having a sufficiently large and large display area is provided inside the operation panel unit 20, and a rice cooking switch 22a, a timer reservation switch 22b, a cancel switch 22c, a heat retention switch 22d, and a reheating switch are disposed around the liquid crystal display unit 21. Various operation switches such as 22e, a menu selection switch 22f, an hour switch 22g, a minute switch 22h, and an energy saving switch 22i which is an energy saving mode selection means are arranged.

  An operation board 5B is provided inside the operation panel 20 at a predetermined interval. On the operation board 5B, contact portions of each of the various operation switches 22a to 22i, a backup power source, a liquid crystal display unit 21, and the like are provided.

  Further, a center sensor storage space portion that is concentrically penetrated in the vertical direction is formed in the central portion of the coil base 7 below the inner case 4 and can be moved up and down in the center sensor storage space portion. A center sensor CS including an inner pot temperature detection sensor (temperature detection means) S and an inner pot detection switch LS is provided in a state that is always upwardly biased by a coil spring.

  On the other hand, reference numeral 2 denotes a lid unit. The lid unit 2 is detachably provided on the outer cover 12 constituting the outer peripheral surface, the inner cover 13 constituting the inner peripheral surface, and the lower side of the inner cover 13. And a heat sink 16 made of metal. In addition, the code | symbol 14 is the packing provided in the outer peripheral part of the said heat sink 16 so that it might correspond to the opening edge part 3c of the inner pot 3. FIG.

  The lid unit 2 is rotatably attached to the shoulder member 11 at the upper part of the outer case 1 via a hinge mechanism, and is engaged with a predetermined position of the lid unit 2 on the open end side. Thus, a lock mechanism 18 that opens and closes the lid unit 2 in the vertical direction is provided.

<Overall configuration and operation of the control circuit portion of the rice cooker body>
Next, FIG. 3 shows the above-described microcomputer control unit 32 that performs rice cooking / cooking and heat retention control (normal / energy saving) on the rice cooker body side configured as described above, display control of the liquid crystal panels 21a and 21b, and other controls. 1 shows the overall configuration of the control circuit portion centering on.

  3, in addition to the rice cooking heating control means, the heat retaining heating control means, and the liquid crystal panel display control means as described above, the rice cooking / heat keeping provided with the inner pot temperature determining means, the inner pot detecting means, the buzzer notifying means, and the like. A microcomputer control unit (CPU) for display control, and the microcomputer control unit 32 is mainly composed of a microcomputer. For example, the temperature detection function of the inner pot 3, the work coil drive control function, and the set state detection of the inner pot 3 It has a function, a drive control function such as a heat retaining heater and a shoulder heater.

  And first, in the temperature detection circuit 43 and the inner pot detection circuit 44 provided corresponding to the inner pot temperature detection sensor S, the inner pot detection switch LS of the bottom wall 3a side center sensor CS part of the inner pot 3, For example, the temperature detection signal of the bottom wall portion 3a of the inner pot 3 by the inner pot temperature detection sensor S and the inner pot detection signal by the inner pot detection switch LS are input.

The work coil drive control circuit 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 microcomputer control unit 32, the output value of the work coil C (C ₁ , C ₂ ) and the ON duty ratio at the same output value according to the rice cooking process ( For example, n seconds / 16 seconds) are appropriately changed, and the heating temperature and the 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, uniform water absorption action and uneven heating Appropriate output control is implemented to realize the cooking of rice without any problems.

Further, the microcomputer control unit 32 controls the heat retaining heater drive circuit 33 and the shoulder heater drive circuit 34, respectively, so that the output values of the heat retaining heaters H ₁ and shoulder heaters H ₂ and the same value are controlled according to, for example, the heat retaining or rice cooking process. By appropriately changing the ON duty ratio (for example, n seconds / 16 seconds) at the output value, the heating temperature and the heating pattern of the inner pot 3 in each step of the heat insulation or rice cooking process are considered in consideration of the actual rice cooking amount. Appropriate output control for appropriately variable control is performed.

  Reference numerals 22a to 22i denote the above-described various input switch sections. When necessary ones of the switches are appropriately operated, first, the user's instruction content is recognized by the recognition means on the microcomputer control unit 32 side. A desired rice cooking or heat insulation heating pattern is set according to the recognition contents, and the rice cooking heating control means or the heat insulation heating control means is appropriately operated to perform desired rice cooking / cooking or heat insulation.

  2 is a rice cooking display lamp, 23b is a heat retention display lamp, 23c is a reservation display lamp, 23d is an energy saving display lamp, and 39 in FIG. 3 is a flywheel diode of the IGBT 37, Reference numeral 35 denotes a power supply side rectifier circuit having a built-in diode bridge for driving the work coil inserted between the household AC power supply 30, and reference numeral 36 denotes a smoothing circuit.

<Insulation control performed after the cooking detection through the unevenness process>
Next, the flowchart of FIG. 4 and the time charts of FIGS. 5, 6, and 7 show the contents of the heat retention control in the present embodiment that is performed through the unevenness process after detection of cooking.

In the same control, after the start of control, first, whether or not the detection of cooking is performed at the current stage, that is, after the start of cooking, the water in the inner pot 3 disappears through each process of water absorption, cooking, and boiling maintenance, It is determined whether or not the cooked state is determined when the temperature T of the rice rises more rapidly than 100 ° C. (step S ₁ ).

When it is determined that the cooking has been detected (YES), it is subsequently determined whether or not the current temperature T of the rice has decreased to a predetermined low temperature, for example, 80 ° C. or less (step S ₂ ). As a result, when the temperature T of the rice does not decrease to 80 ° C. or lower, the determination operation (80 ° C. or lower?) Is repeated until the temperature T of the rice reaches 80 ° C. or lower. wait.

  This temperature of 80 ° C. is selected as a reference temperature for determining whether the germs in the rice can survive or die when the germs invade into the rice. It has been confirmed that the germs killed and live at 80 ° C. or lower.

On the other hand, when the temperature T of the rice is reduced to 80 ° C. or lower, if the lid 2 is opened as described above, there is a possibility that the invading bacteria may grow. It is detected and determined whether or not it has been opened (step S ₃ ). The detection of the opening of the lid 2 is made based on whether or not the temperature of the inner pot 3 detected by the inner pot temperature detection sensor S of the sensor sensor CS described above has decreased by a predetermined value or more within a predetermined time. The

As a result, in the case where the lid is not opened (the lid 2 is not opened), it is assumed that there is no need to perform the above-described temperature increase control because no invasion of germs into the inner pot 3 is assumed. Temperature process path information is set (step S ₄ ).

Then, the process proceeds to a determination operation (step S ₅ ) for determining whether or not the temperature increase start time (time point t _{1 in} FIG. 6) for performing temperature increase control has been reached.

On the other hand, when there is actually the lid 2 open (detection) jumps the setting operation of the heating process path information in step S _4, the temperature increase start time for performing the Atsushi Nobori control (in FIG. 5 It determines whether reached t ₁ elapsed time) of (step S _5).

  In the determination of whether or not the temperature increase control according to the open / close state of the lid 2 is passed, a condition determination of “determination temperature> temperature acquired from the temperature detection sensor S of the center sensor CS + 1 ° C.” is performed. When the same condition is satisfied, the lid open detection is performed for the first time.

To get the temperature from the temperature detection sensor S, ON warmth heater H _1, performs offset considering hunting (see FIG. 7) by overshoot based on OFF + 1 ° C., when even lower than the determination temperature at that temperature For the first time, it is determined that the lid 2 is opened and the temperature of the rice has dropped.

Then the temperature increase start time when has reached (FIG. 5, t ₁ elapsed time in FIG. 6), once determined whether the (step had set heating step path information in step S ₄ S ₆ ) is performed, and according to the determination result, when the temperature of the rice without the same path information setting is 80 ° C. or less, the temperature of the rice further decreases when the lid 2 is opened and various germs enter. In this case, miscellaneous bacteria propagate, so that the temperature rise control is performed as shown in the time chart of FIG. 5 to increase the temperature of the rice to achieve sterilization (step S ₇ ).

  On the other hand, if the lid 2 that has been set with the temperature raising process path information is not opened, there is no invasion of germs, and the temperature of the rice continues at the original set temperature, so that the propagation of germs does not occur. Therefore, there is no problem even if the temperature raising control as shown in FIG. 5 is not performed.

  Therefore, in this case, as shown in the time chart of FIG. 6, the temperature increase control as shown in the time chart of FIG. 5 is passed, and the normal heat retention control based on the set heat retention temperature (see FIG. 6). Continue.

In the conventional control shown in FIG. 9, the set heat retention temperature Ts is gradually increased to Ts ₁ and Ts ₂ as the heat retention time t becomes longer. In this embodiment, the set heat retention temperature Ts ₁ is set to the total heat retention time. Since the common temperature is set, the set heat retention temperature Ts ₁ can be continued as it is even if the temperature raising control is passed as described above (the comparison between FIG. 5 and FIG. 6). As a result, power consumption can be further saved.

However, as shown in the time chart of FIG. 8, for example, when the temperature increase control is performed, the set heat retention temperature (maintenance temperature) Ts is increased to predetermined values ΔT ₁ and ΔT ₂ each time. Needless to say.

  As described above, in the present invention, after the completion of rice cooking, the state of energization to the heat-retaining and heating means is controlled so as to maintain the temperature of the rice at the heat-retaining temperature set in advance, and during the heat-retaining control, a predetermined time is set. In the electric rice cooker provided with a heat retention control means for raising the temperature of the rice when the time has passed, the lid of the rice cooker is opened during the heat retention process after detecting the cooking and during the heat retention process. If not, temperature rise control for raising the temperature of the rice is not performed.

  According to such a configuration, the lid of the rice cooker is not opened after detection of cooking, and therefore, when there is no invasion of germs, the temperature increase control for sterilization is omitted, and the normal heat retention control is continued. Therefore, power consumption can be saved accordingly.

  Moreover, in this invention, even if the lid | cover of a rice cooker is opened in said structure, when the temperature of rice is more than predetermined high temperature which can kill the invading miscellaneous bacteria, temperature rising control is performed. I am trying not to.

  According to such a configuration, as described above, even if the lid of the rice cooker is opened and miscellaneous germs have invaded, after the cooking has been detected, it is in the middle of shifting to the set heat retention temperature through the unevenness process. When the temperature of the rice is in a high temperature state that can kill germs, the temperature increase control for sterilization described above is omitted, and normal heat retention control is continued, thus saving power consumption accordingly. be able to.

  Moreover, in this invention, in said structure, the temperature detection means which detects the temperature of an inner pot was provided, and the lid | cover of the rice cooker opened when the temperature of the inner pot detected by this temperature detection means fell more than predetermined value. I try to detect that.

  According to such a configuration, it is determined that the lid of the rice cooker has been opened when the temperature of the inner pot detected by the temperature detecting means has decreased by a predetermined value or more, and sterilization can be performed by performing necessary temperature rise control. Can do.

  Further, according to the present invention, in the above-described configuration, the detection of the lid open / closed state in the heat retention control state at the set heat retention temperature is a fluctuation range of the detected temperature when the heating amount of the heating unit is increased / decreased based on the set heat retention temperature. This is performed based on the temperature decrease range corrected for the above.

  Control of the heat retaining heating means in the heat retaining step is performed by turning the triac on and off by, for example, a microcomputer control unit. The microcomputer-type control unit has a target heat retention temperature set in advance by the user. When the temperature detected by the temperature detection means is lower than the set temperature, the heat insulation heating means is energized. The heat insulation temperature is kept constant.

  In other words, this control is a two-position ON-OFF control in terms of the control system, and naturally involves an overshoot of a predetermined width in two directions between the two positions.

  Accordingly, even when the temperature detection means detects a temperature drop of a predetermined width or more to detect opening / closing of the lid, the detection is performed in consideration of the fluctuation range due to the overshoot. Thereby, it is possible to accurately detect the lid open / closed state with the fluctuation range offset.

  As a result of the above, according to the present invention, it is possible to prevent the proliferation of germs and to reduce the power consumption during the heat retention by reducing the temperature rise control.

C ₁ , C ₂ , C are work coils, H ₁ is a warming heater, H ₂ is a shoulder heater, 1 is an outer case, 2 is a lid unit, 3 is an inner pan, 20 is an operation panel, 21 is a liquid crystal display section, 32 Is a microcomputer control unit.

Claims (4)

  After rice cooking is finished, the temperature of the rice is controlled when a predetermined time elapses during the heat insulation control while controlling the energization state to the heat insulation heating means so as to maintain the temperature of the rice at a preset heat insulation temperature. In the electric rice cooker provided with a heat retention control means for raising the temperature of the rice cooker, if the rice cooker lid is not opened during the heat retention process and after the heating is detected, An electric rice cooker characterized by not performing temperature rise control for raising the temperature.   Even if the lid of the rice cooker is opened, temperature control is not performed when the temperature of the rice is higher than a predetermined high temperature at which invading bacteria can be killed. The electric rice cooker according to 1.   A temperature detecting means for detecting the temperature of the inner pot is provided, and when the temperature of the inner pot detected by the temperature detecting means is lowered by a predetermined value or more, it is detected that the lid of the rice cooker is opened. The electric rice cooker according to claim 1 or 2.   Detection of the open / closed state of the lid in the heat retention control state at the set heat retention temperature is performed based on the temperature decrease range obtained by correcting the fluctuation range of the detected temperature when the heating amount of the heating means is increased or decreased based on the set heat retention temperature. The electric rice cooker according to claim 1, 2 or 3, wherein

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