JP3772844B2 - Electric rice cooker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
[0002]
The present invention relates to an electric rice cooker, and more particularly to heat retention control of an electric rice cooker.
[Prior art]
[0003]
In general, in an electric rice cooker, when the temperature is lowered, spoilage bacteria are likely to grow and the flavor is impaired. On the other hand, when the temperature is raised, the rice is yellowed or browned.
[0004]
By the way, there is a case where the heat control is performed following the cooking, and a case where the heat control is performed by operating a heat key that acts as a heat start means. Therefore, when the same heat retention control is performed, the state of the rice may be deteriorated.
[0005]
Therefore, if you want to keep warm after the end of cooking rice, first keep warm at a low temperature, then increase the warming temperature when a predetermined time has passed, and if you keep warm by operating the warming key, An electric rice cooker that performs heat insulation has been proposed (see, for example, Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent No. 3298093
[Problems to be solved by the invention]
[0007]
However, in the case of the electric rice cooker disclosed in the above-mentioned Patent Document 1, the heat retention by the operation of the heat retention key is to perform the high temperature heat retention, so that it may be yellowed or browned depending on the temperature of the rice. In addition, there is a problem that power consumption increases.
[0008]
This invention is made | formed in view of said point, and aims at aiming at the improvement of the state of rice, and energy saving in the case of heat-retaining by operation of a heat-retaining key.
[Means for Solving the Problems]
[0009]
In the present invention, in order to solve the above problems hand of As a stage, a rice cooking control means for performing the rice cooking operation, a heat insulation control means for performing the heat insulation operation by switching the temperature of the rice between a low temperature and a high temperature, and a heat insulation start means for starting only the heat insulation operation by the heat insulation control means are provided. In the electric rice cooker, the heat retaining control means performs low temperature heat retaining control to keep the heat retaining temperature low when performing the heat retaining operation following the rice cooking operation by the rice cooking controlling means and when the heat retaining operation by the heat retaining start means is started. At the same time, when the heat retaining operation by the heat retaining starting means is started, the heat retaining control means always enters the low temperature heat retaining control once, and the low temperature warming time by the low temperature heat retaining control is kept warm after the rice cooking operation of the white rice by the rice cooking controlling means. Compared to the case where the operation is performed, it is shortened.
[0010]
By configuring as described above, when performing the heat retaining operation following the rice cooking operation and when the heat retaining operation by the heat retaining start means is started, the temperature keeping control is always performed to make the heat retaining temperature low. When starting the warming operation by, the low temperature warming time will be shortened compared to the case of performing the warming operation following the rice cooking operation of white rice, and it is possible to perform the warming by the warming control according to the rice state, Energy saving can be achieved by shortening the low temperature insulation time.
DETAILED DESCRIPTION OF THE INVENTION
[0011]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0012]
This electric rice cooker is configured so as to accommodate a rice cooker 3 for cooking rice inside, and has a double structure rice cooker body 1 having a space portion 4, and an upper opening of the rice cooker body 1 can be freely opened and closed. And a lid 2 for covering.
[0013]
The rice cooker main body 1 has an outer case 5 made of a synthetic resin integrally formed with a body portion 5a serving as an outer wall and a bottom portion 5b serving as a bottom wall, and a bottomed cylindrical shape made of synthetic resin serving as an inner peripheral wall. The protective frame 6 includes a synthetic resin shoulder member 7 that joins the upper end of the protective frame 6 and the upper end of the outer case 5, and is surrounded by the outer case 5, the protective frame 6, and the shoulder member 7. Thus, the space 4 is formed. In addition, the rice cooker 3 is accommodated in the protective frame 6 so as to be removable.
[0014]
A sensor hole 9 is formed in the center of the bottom surface of the protective frame 6 for allowing the center sensor 8 acting as temperature detecting means for detecting the rice cooker temperature.
[0015]
An annular electromagnetic induction coil (hereinafter referred to as a work coil) 10 acting as a heating means during rice cooking so as to surround the sensor hole 9 is a bent portion between the bottom surface of the protective frame 6 and the bottom surface to the side peripheral surface. It is arranged corresponding to. The work coil 10 generates an alternating magnetic field (in other words, an electromagnetic wave), generates an induced eddy current in the rice cooker 3 by electromagnetic induction of the alternating magnetic field, and uses the resistance heat of the induced eddy current. And heated. The rice cooker 3 is made of a material (for example, a magnetic material) that can generate an induced eddy current by the work coil 10.
[0016]
The work coil 10 is sandwiched between a coil die 11 fixed to the bottom surface of the protective frame 6 and the bottom surface of the protective frame 6. Reference numeral 12 denotes a ferrite core, which acts to block the magnetic field generated by the work coil 10 so as not to affect the underlying device.
[0017]
A center sensor 8 is provided in the sensor hole 9 so as to contact the bottom of the rice cooker 3. A heat retaining heater 13 that acts as a heating means at the time of heat retention is attached to the side peripheral surface of the protective frame 6.
[0018]
On the bottom of the rice cooker body 1 (that is, the bottom 5b of the outer case 5), cooling air is supplied to electronic components such as a power transistor and a rectifier diode bridge (not shown) for controlling the energization of the work coil 10. An electronic component cooling fan 14 to be pumped is provided. An air inlet 15 is formed in the bottom wall of the rice cooker body 1 (specifically, the bottom portion 5b of the outer case 5) so as to face the electronic component cooling fan 14.
[0019]
On the other hand, the lid 2 is composed of a synthetic resin upper plate 16 constituting the outer surface and a synthetic resin lower plate 17 constituting the inner surface, and is a space surrounded by the upper and lower plates 16, 17. The part 18 is provided with a heat insulating material 19.
[0020]
The lid 2 is attached to the rice cooker body 1 via a hinge unit 20 formed on one side of the shoulder member 7 so as to be freely arc-turnable and detachable.
[0021]
And the cylindrical part 21 suspended from the said upper board 16 is formed in the center part of the said cover body 2, In this cylindrical part 21, it is for discharging | emitting the water vapor | steam generated at the time of rice cooking outside. A steam cap 23 having a steam discharge passage 22 is detachably attached. A ball valve 24 acting as a pressure regulating valve is disposed in the steam cap 23. At the lower end of the steam cap 23, a heat radiating plate 25 made of a good heat conductor (for example, aluminum alloy) is attached to seal the opening 3a of the rice cooker 3 when the lid 2 is closed. Reference numeral 26 denotes a steam inlet to the steam cap 23, 27 denotes a steam outlet from the steam cap 24, 28 denotes a steam port formed in the heat sink 25, and 29 denotes a peripheral edge of the heat sink 25 and the opening 3 a of the rice cooker 3. A seal packing 30 for sealing the gap between the heat sink 25 and the lid lower plate 17 is provided.
[0022]
The shoulder member 7 is provided with a shoulder heater 31, and the outer peripheral edge of the heat radiating plate 25 is pressed against the shoulder heater 31 when the lid 2 is closed. It is supposed to be heated by heat conduction. The shoulder heater 31 includes a heater ring 32 having an inverted U-shaped cross section and a heating element 33 disposed in the heater ring 32.
[0023]
In addition, the lid 2 is located inward of the heat radiating plate 25 and faces inward from the opening 3a of the rice cooker 3 with a space interposed between the lid 2 and the heat radiating plate 25. In addition, an inner lid 34 made of a good thermal conductor supported with its outer periphery being brought close to the inner peripheral surface of the rice cooker 3 is provided. The inner lid 34 is attached to a seal packing 36 that is detachably fitted to a support shaft 35 that projects downward from the center of the steam cap 23.
[0024]
In the space part 4 in the side part (for example, the hinge unit 20 side) in the said rice cooker main body 1, the ventilation fan 37 is arrange | positioned in the state attached to the said shoulder member 7. FIG. The blower fan 37 is a centrifugal fan having a scroll type fan casing.
[0025]
A duct 38 is connected to the discharge port 37 a of the blower fan 37, and an upper end of the duct 38 faces an inlet 39 a of an annular passage 39 formed in the shoulder member 7. The shoulder member 7 is formed with a plurality of communication ports 40 communicating with the annular passage 39 and the upper part of the annular gap C formed between the rice cooker 3 and the protective frame 6. . That is, the air blown from the blower fan 37 is supplied to the upper portion of the gap C through the duct 38, the annular passage 39 and the communication port 40. Reference numeral 41 denotes an air intake formed at the lower part of the body portion 5 a of the outer case 5.
[0026]
In the space 4 on the anti-hinge side of the rice cooker body 1 (that is, the side on which the lock mechanism 42 that locks the lid 2 is provided), the work coil 10, the heat retaining heater 13, the shoulder heater 31 and the like are energized. A control board 43 in which a control unit for controlling the control is installed is disposed. On the anti-hinge side of the shoulder member 7 (that is, the side on which the lock mechanism 42 for locking the lid body 2 is provided) An operation panel unit 44 including operation keys (for example, a rice cooking key, a reservation key, etc.) and a liquid crystal display device acting as a display device is provided.
[0027]
As shown in FIG. 2, the operation panel 44 includes a rice cooking key 46, a reservation key 47, a cancel key 48, a heat retention key 49, a reheating key 50, a menu key 51, a liquid crystal display device 52, an hour key 53 and a minute. A key 54 is provided. Around the liquid crystal display device 52, various menus (“white rice”, “quick cook”, “brown rice”, “rice porridge” displayed by moving an arrow 52 a of the liquid crystal display device 52 according to the operation of the menu key 51 are displayed. ”,“ Cooking ”,“ rice cake ”and“ pilaf ”). The liquid crystal display device 52 includes a time display unit 52b that displays the current time and a temperature display unit 52c that displays the rice cooker temperature detected by the center sensor 8. Here, the heat retention key 49 is to select normal heat retention by one press operation and to select low temperature heat retention by two press operations.
[0028]
Next, the electrical configuration of the electric rice cooker according to the present embodiment will be described based on the electrical circuit diagram shown in FIG. Parts corresponding to the respective parts shown in FIGS. 1 and 2 are denoted by the same reference numerals.
[0029]
The electric power from the commercial AC power supply 55 is supplied to the work coil 10 through the temperature fuse 56 and the rectifier circuit 57 that are blown by detecting abnormal heating of the rice cooker 3, and is also supplied to the heat retaining heater 13 and the shoulder heater 31. It is supposed to be. Reference numeral 58 is a smoothing capacitor, 59 is a resonance capacitor, 60 and 61 are heater drive circuits, and 62 is a backup battery that acts as an auxiliary power supply that operates when the AC power supply 55 is not connected.
[0030]
The work coil 10 is supplied with a control signal from a power transistor 65 that is ON / OFF controlled by a command from a microcomputer unit (hereinafter abbreviated as a microcomputer) 63 through an IGBT drive circuit 64.
[0031]
The microcomputer 63 controls the power transistor 65 in accordance with a predetermined program, thereby controlling energization to the work coil 10. This energization control is performed based on an output signal from the thermistor 66 incorporated in the center sensor 8 (see FIG. 1).
[0032]
Next, with reference to the flowcharts shown in FIGS. 4 to 7 and the time charts shown in FIGS. 8 to 12, the heat retention control in the electric rice cooker according to the present embodiment will be described in detail.
(I) Thermal insulation control I
The heat insulation control I will be described with reference to the flowchart shown in FIG.
[0033]
In step S1, it is determined whether or not the rice cooking has been completed. If an affirmative determination is made here, a determination is made in step S2 as to whether or not the rice was cooked. If an affirmative determination is made here, a step is performed. In S3, low temperature heat retention control is executed. As shown in the time chart of FIG. 8, the low temperature insulation control is performed by changing the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Control (for example, 68 degreeC) is performed.
[0034]
In the low temperature heat retention control, the rice temperature after the completion of cooking in step S4 is the low temperature setting temperature Ts. ₁ A predetermined time t ₁ Continue until it is determined that (for example, 4 hours) has elapsed. If an affirmative determination is made in step S4, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S5. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0035]
If it is determined in step S6 that the temperature raising step has ended, medium temperature heat retention control is executed in step S7. As shown in the time chart of FIG. 8, the intermediate temperature keeping control is performed by setting the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Higher medium temperature set temperature Ts ₂ Control (for example, 70 degreeC) is performed.
[0036]
The intermediate temperature keeping control is performed for a predetermined time t in step S8. ₂ Continue until it is determined that (for example, 7 hours) has elapsed. If an affirmative determination is made in step S8, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S9. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time of the temperature raising step is extremely short.
[0037]
If it is determined in step S10 that the temperature raising step has ended, high temperature heat retention control is executed in step S11. As shown in the time chart of FIG. 8, the high temperature insulation control is performed by changing the detected temperature T of the temperature sensor 8 to the intermediate temperature set temperature Ts. ₂ Higher set temperature Ts _Three Control (for example, 72 degreeC) is performed.
[0038]
On the other hand, if a negative determination is made in step S2 (that is, rice cooking other than white rice = for example, in the case of cooked rice cooking or rice cooking rice), the process proceeds to step S12 and low temperature heat retention control is executed. As shown in the time chart of FIG. 9, the low temperature keeping control is performed by changing the temperature T detected by the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Control (for example, 68 degreeC) is performed.
[0039]
In the low temperature heat retention control, the rice temperature after the completion of cooking in step S13 is the low temperature setting temperature Ts. ₁ A predetermined time t ₁ ′ (For example, 1 hour) <t ₁ Continue until it is determined that has passed. If an affirmative determination is made in step S13, the process proceeds to step S5, and the subsequent control described above is executed.
[0040]
Further, if a negative determination is made in step S1, the process proceeds to step S14. When the heat retention key 49 is turned on here, the process proceeds to step S15, and the low temperature heat retention control is executed. As shown in the time chart of FIG. 9, the low temperature keeping control is performed by changing the temperature T detected by the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Control (for example, 68 degreeC) is performed.
[0041]
The low temperature heat retention control is performed for a predetermined time t from when the heat retention key 49 is turned on in step S16. ₁ ′ (For example, 1 hour) <t ₁ Continue until it is determined that has passed. When an affirmative determination is made in step S16, the process proceeds to step S5, and the subsequent control described above is executed.
[0042]
As described above, in this case, when performing the heat retaining operation following the rice cooking operation and when the heat retaining operation by the heat retaining key 49 is started, low temperature heat insulation control is performed to lower the heat retaining temperature, but for rice cooking operations other than white rice In the case of continuing the warming operation or starting the warming operation by the warming key 49, the low temperature warming time t when performing the low temperature warming following the white rice cooking. ₁ (For example, 6 hours) shorter heat retention time t ₁ '(For example, 1 hour). Accordingly, it is possible to perform heat retention by heat retention control in accordance with the rice state, and to achieve energy saving by shortening the low temperature heat retention time. In addition, since the heat retention temperature is increased stepwise after the low temperature heat retention, yellowing and browning can be prevented while preventing the rice from being spoiled. Furthermore, when the temperature is increased stepwise, the high temperature temperature Ts _Three Since a short temperature raising step of heating to a higher temperature Tsh is performed, the growth of spoilage bacteria can be suppressed.
(II) Thermal insulation control II
The heat retention control II will be described with reference to the flowchart shown in FIG.
[0043]
When the heat retention key 49 is turned on in step S1, the heat retention control is suspended in step S2. The temperature keeping control is suspended to wait until the temperature of the rice put in the rice cooker 3 can be detected by the temperature sensor 8. This heat retention control suspension is continued until it is determined in step S3 that 3 minutes have elapsed.
[0044]
If an affirmative determination is made in step S3, the detected temperature (in other words, rice temperature) T of the temperature sensor 8 is input to the microcomputer 63 in step S4, and the detected temperature T and the set temperature Ts (for example, 68) in step S5. In the case where it is determined that T ≦ Ts, the low temperature heat retention control is executed in step S6. As shown in the time chart of FIG. 10, the low temperature insulation control is performed by changing the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Control (for example, 68 degreeC) is performed.
[0045]
The low temperature heat retention control is performed for a predetermined time t from when the heat retention key 49 is turned on in step S7. ₁ Continue until it is determined that ′ (for example, 1 hour) has elapsed. If an affirmative determination is made in step S7, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S8. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0046]
If it is determined in step S9 that the temperature raising step has been completed, medium temperature heat retention control is executed in step S10. As shown in the time chart of FIG. 10, the intermediate temperature keeping control is performed by setting the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Higher medium temperature set temperature Ts ₂ Control (for example, 70 degreeC) is performed.
[0047]
The intermediate temperature keeping control is performed for a predetermined time t in step S11. ₂ Continue until it is determined that (for example, 7 hours) has elapsed. If an affirmative determination is made in step S11, the detected temperature T of the temperature sensor 8 is the high temperature set temperature Ts in step S12. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0048]
If it is determined in step S13 that the temperature raising process has ended, high temperature heat retention control is executed in step S14. As shown in the time chart of FIG. 10, the high temperature insulation control is performed by changing the detected temperature T of the temperature sensor 8 to the intermediate temperature set temperature Ts. ₂ Higher set temperature Ts _Three Control (for example, 72 degreeC) is performed.
[0049]
On the other hand, if it is determined in step S5 that T> Ts, the process proceeds directly to step S10, where the intermediate temperature keeping control is executed, and thereafter the above-described control is executed (see the time chart of FIG. 11). That is, in this case, the low temperature heat retention control and the subsequent temperature raising step are omitted.
[0050]
As described above, in this case as well, energy saving can be achieved by shortening the low temperature heat retention time, and the heat retention temperature is gradually increased after the low temperature heat insulation is completed. While preventing, yellowing and browning can also be prevented. Furthermore, when the temperature is increased stepwise, the high temperature temperature Ts _Three Since a short temperature raising step of heating to a higher temperature Tsh is performed, the growth of spoilage bacteria can be suppressed.
[0051]
Further, at the start of the warming operation by turning on the warming key 49, the low temperature warming temperature is changed according to the temperature of the rice (in other words, the low temperature warming is omitted when the temperature of the rice is high). Although the state of the rice is not constant in the heat insulation by the key 49, the heat insulation control corresponding to the state of the rice can be obtained by changing the low temperature heat insulation temperature according to the temperature of the rice.
[0052]
During the above low temperature heat control, the output of the work coil 10 is gradually increased corresponding to the heat retention elapsed time (for example, the duty ratio is changed to 1/16 → 2/16 → 3/16... Is preferable in order to prevent the spoilage of rice.
[0053]
Further, the set temperature Tsh in the temperature raising step can be set higher than the case where the temperature is kept continuously from the rice cooking. By doing so, it is possible to further suppress the rot of rice during the heat insulation.
(III) Thermal insulation control III
The heat retention control III will be described with reference to the flowchart shown in FIG.
[0054]
When the heat retention key 49 is turned on in step S1, reheating control is executed in step S2. The reheating control is the same control as when the reheating key 50 is turned on, and heats to the same temperature as in the temperature raising process. The reason for performing the reheating control is to stabilize the rice state by the reheating control because the state of the rice at the time of the ON operation of the heat retention key 49 cannot be determined.
[0055]
If it is determined in step S3 that the reheating control has been completed, the low temperature heat retention control is executed in step S4. As shown in the time chart of FIG. 12, the low temperature insulation control is performed by changing the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Control (for example, 68 degreeC) is performed.
[0056]
The low temperature insulation control is performed for a predetermined time t after completion of reheating in step S5. ₁ Continue until it is determined that (for example, 4 hours) has elapsed. If an affirmative determination is made in step S5, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S6. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0057]
If it is determined in step S7 that the temperature raising step has been completed, medium temperature heat retention control is executed in step S8. As shown in the time chart of FIG. 12, the intermediate temperature keeping control is performed by changing the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Higher medium temperature set temperature Ts ₂ Control (for example, 70 degreeC) is performed.
[0058]
The intermediate temperature keeping control is performed for a predetermined time t in step S9. ₂ Continue until it is determined that (for example, 7 hours) has elapsed. If an affirmative determination is made in step S9, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S9. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0059]
If it is determined in step S11 that the temperature raising step has been completed, high temperature heat retention control is executed in step S12. As shown in the time chart of FIG. 12, the high temperature heat retention control is performed by changing the detected temperature T of the temperature sensor 8 to the intermediate temperature set temperature Ts. ₂ Higher set temperature Ts _Three Control (for example, 72 degreeC) is performed.
[0060]
As described above, also in this case, since the heat retention temperature is gradually increased after completion of the low temperature heat retention, it is possible to prevent yellowing and browning while preventing the spoilage of rice. Furthermore, when the temperature is increased stepwise, the high temperature temperature Ts _Three Since a short temperature raising step of heating to a higher temperature Tsh is performed, the growth of spoilage bacteria can be suppressed.
[0061]
Furthermore, when the heat retaining operation is started by turning on the heat retaining key 49, the state of the rice is stabilized by the reheating control, so that the heat retaining control independent of the state of the rice can be obtained.
[0062]
During the above low temperature heat control, the output of the work coil 10 is gradually increased corresponding to the heat retention elapsed time (for example, the duty ratio is changed to 1/16 → 2/16 → 3/16... Is preferable in order to prevent the spoilage of rice.
[0063]
Further, the set temperature Tsh in the temperature raising step can be set higher than the case where the temperature is kept continuously from the rice cooking. By doing so, it is possible to further suppress the rot of rice during the heat insulation.
(IV) Thermal insulation control IV
With reference to the flowchart shown in FIG. 7, the heat insulation control IV will be described.
[0064]
When the heat retention key 49 is turned on in step S1, the heat retention control is suspended in step S2. The temperature keeping control is suspended to wait until the temperature of the rice put in the rice cooker 3 can be detected by the temperature sensor 8. This heat retention control suspension is continued until it is determined in step S3 that 3 minutes have elapsed.
[0065]
If an affirmative determination is made in step S3, the detected temperature (in other words, rice temperature) T of the temperature sensor 8 is input to the microcomputer 63 in step S4, and the detected temperature T and the set temperature Ts (for example, 72) are input in step S5. When it is determined that T ≦ Ts (that is, when the rice temperature is low), reheating control is executed in step S6. The reheating control is the same control as when the reheating key 50 is turned on, and heats to the same temperature as in the temperature raising process. The reason for performing the reheating control is to stabilize the rice state by the reheating control because the state of the rice at the time of the ON operation of the heat retention key 49 cannot be determined.
[0066]
If it is determined in step S7 that the reheating control has been completed, the low temperature heat retention control is executed in step S8. As shown in the time chart of FIG. 12, the low temperature insulation control is performed by changing the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Control (for example, 68 degreeC) is performed.
[0067]
The low temperature insulation control is performed for a predetermined time t after completion of reheating in step S9. ₁ Continue until it is determined that (for example, 4 hours) has elapsed. If an affirmative determination is made in step S9, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S10. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0068]
If it is determined in step S11 that the temperature raising step has ended, medium temperature heat retention control is executed in step S12. As shown in the time chart of FIG. 12, the intermediate temperature keeping control is performed by changing the detected temperature T of the temperature sensor 8 to the low temperature setting temperature Ts. ₁ Higher medium temperature set temperature Ts ₂ Control (for example, 70 degreeC) is performed.
[0069]
The intermediate temperature keeping control is performed for a predetermined time t in step S13. ₂ Continue until it is determined that (for example, 7 hours) has elapsed. If an affirmative determination is made in step S13, the detected temperature T of the temperature sensor 8 is changed to the high temperature set temperature Ts in step S14. _Three A temperature raising step for raising the temperature to a set temperature Tsh (eg, 110 ° C.) higher than (eg, 72 ° C.) is performed. In the temperature raising step, energization to the work coil 10 is stopped when the detected temperature T reaches the set temperature Tsh, and the time for the temperature raising step is extremely short.
[0070]
If it is determined in step S15 that the temperature raising process has ended, high temperature heat retention control is executed in step S16. As shown in the time chart of FIG. 12, the high temperature heat retention control is performed by changing the detected temperature T of the temperature sensor 8 to the intermediate temperature set temperature Ts. ₂ Higher set temperature Ts _Three Control (for example, 72 degreeC) is performed.
[0071]
On the other hand, if it is determined in step S5 that T> Ts (that is, the rice temperature is high), the process proceeds directly to step S8, and the subsequent control is executed (see the dotted line in FIG. 12). That is, reheating control is omitted.
[0072]
As described above, also in this case, since the heat retention temperature is gradually increased after completion of the low temperature heat retention, it is possible to prevent yellowing and browning while preventing the spoilage of rice. Furthermore, when the temperature is increased stepwise, the high temperature temperature Ts _Three Since a short temperature raising step of heating to a higher temperature Tsh is performed, the growth of spoilage bacteria can be suppressed.
[0073]
In addition, since the state of the rice is stabilized by reheating control at the start of the heat retaining operation by turning on the heat retaining key 49, the heat retaining control independent of the state of the rice can be obtained.
[0074]
Moreover, since the reheating control is omitted when the rice temperature is high, energy saving can be achieved.
[0075]
During the above low temperature heat control, the output of the work coil 10 is gradually increased corresponding to the heat retention elapsed time (for example, the duty ratio is changed to 1/16 → 2/16 → 3/16... Is preferable in order to prevent the spoilage of rice.
[0076]
Further, the set temperature Tsh in the temperature raising step can be set higher than the case where the temperature is kept continuously from the rice cooking. By doing so, it is possible to further suppress the rot of rice during the heat insulation.
[0077]
In the above embodiment, the work coil is employed as the heating means, but an electric heater or the like may be employed as the heating means.
【The invention's effect】
[0078]
From this application Clearly According to the invention, the rice cooking control means for performing the rice cooking operation, the heat retaining control means for performing the heat retaining operation by switching the temperature of the rice between the low temperature and the high temperature, and the heat retaining starting means for starting only the heat retaining operation by the heat retaining control means are provided. In the electric rice cooker, the heat retaining control means performs a low temperature heat retaining control to keep the heat retaining temperature low when performing the heat retaining operation following the rice cooking operation by the rice cooking controlling means and when the heat retaining operation by the heat retaining start means is started. At the same time, when the heat retaining operation by the heat retaining starting means is started, the heat retaining control means always enters the low temperature heat retaining control once, and the low temperature warming time by the low temperature heat retaining control is kept warm after the rice cooking operation of the white rice by the rice cooking control means Since it is shortened compared to the case of performing the operation, it is possible to perform heat insulation by heat insulation control according to the rice state , There is an effect that it is possible to achieve energy saving by reducing the low-temperature incubation time.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an electric rice cooker according to an embodiment of the present invention.
FIG. 2 is a front view of an operation panel unit in the electric rice cooker according to the embodiment of the present invention.
FIG. 3 is a connection diagram of a control circuit unit in the electric rice cooker according to the embodiment of the present invention.
FIG. 4 is a flowchart of heat retention control I in the electric rice cooker according to the embodiment of the present invention.
FIG. 5 is a flowchart of heat retention control II in the electric rice cooker according to the embodiment of the present invention.
FIG. 6 is a flowchart of heat retention control III in the electric rice cooker according to the embodiment of the present invention.
FIG. 7 is a flowchart of heat retention control IV in the electric rice cooker according to the embodiment of the present invention.
FIG. 8 is a time chart showing a change in rice cooker temperature in the case of performing heat insulation subsequent to white rice cooking by heat insulation control I in the electric rice cooker according to the embodiment of the present invention.
FIG. 9 shows the change in rice cooker temperature when the heat retention control I in the electric rice cooker according to the embodiment of the present invention is performed, and when the heat retention is performed subsequent to the cooking of rice other than white rice, or when the heat retention is performed by the ON operation of the heat retention key. It is a time chart.
FIG. 10 is a time chart showing a change in rice cooker temperature when the rice temperature is low in the heat retention control II in the electric rice cooker according to the embodiment of the present invention.
FIG. 11 is a time chart showing changes in the rice cooker temperature when the rice temperature is high in the heat retention control II in the electric rice cooker according to the embodiment of the present invention.
FIG. 12 is a time chart showing changes in the rice cooker temperature of heat retention controls III and IV in the electric rice cooker according to the embodiment of the present invention.
[Explanation of symbols]
3 is a rice cooker, 8 is a temperature detection means (temperature sensor), 10 is an electromagnetic induction coil (work coil), 49 is a heat retention start means (heat retention key), and 63 is a microcomputer unit (microcomputer).

Claims (1)

  An electric rice cooker comprising rice cooking control means for performing rice cooking operation, heat insulation control means for performing heat insulation operation by switching the temperature of rice between low temperature and high temperature, and heat insulation start means for starting only the heat insulation operation by the heat insulation control means And the said heat retention control means performs low temperature heat insulation control which makes the heat insulation temperature low when performing the heat insulation operation following the rice cooking operation by the rice cooking control means and when the heat insulation operation by the heat insulation start means is started. When the warming operation by the warming start means is started, the warming control means always enters the low temperature warming control once, and the low temperature warming time by the low temperature warming control is continued after the rice cooking operation of white rice by the rice cooking control means. An electric rice cooker characterized in that it is shortened compared to the case of performing.

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