JP2890397B2 - rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker in which the temperature for keeping warm rice can be changed in multiple steps.

[0002]

Conventionally, a rice cooker of this type has a temperature in a container of about 70 to 75 when kept warm, as disclosed in, for example, Japanese Patent Publication No. 57-1214.
° C and kill the vegetative cells of the rot-causing bacteria of cooked rice, and when the temperature in the container drops to about 45 to 55 ° C, repeat the process of reaching the temperature in the container to about 70 to 75 ° C again As a result, there has been proposed a type in which cooked rice can be kept in a good condition for a long time by suppressing the generation of browning, putrefaction and unpleasant odor. Japanese Patent Application Laid-Open No. 57-9425 discloses that, in order to prevent yellowing of rice during the heat retention, power supply to the heat retention heater is performed from the end of the rice cooking operation until the set time of the timer device is reached. Block, then
There is disclosed a rice cooker that energizes a warming heater to maintain the inside of a container at a predetermined warming temperature. Further, as a rice cooker for preventing yellowing of rice during the same heat retention, as described in Japanese Patent Application Laid-Open No. Sho 60-149348, a rice cooker is used for rice cooker.
Maintain a temperature of 0-55 ° C and cook rice before eating.
A device in which the temperature is raised to 5 ° C. and a device in which the setting of the heat retention temperature is switched from a low temperature to a high temperature by a timer switch according to the heat retention elapsed time as disclosed in Japanese Utility Model Application Laid-Open No. 58-125532 have been proposed. ing.

In the above prior art, Japanese Patent Laid-Open No. 60-14 / 1985
No. 9348 and Japanese Utility Model Application Laid-Open No. 58-125532 do not have a lid heater for heating the lower surface of the lid during heat insulation, and require some kind of dew receiving mechanism assuming condensation on the lower surface of the lid. Becomes Therefore, when the heat retention temperature is switched to a low temperature in a state where the lower surface of the lid is wet due to dew condensation, the decaying bacteria easily grow on the lower surface of the lid, and the dew drops from the lower surface of the lid to the upper surface of the rice. Then, in combination with the weak sterilizing power at the time of keeping the temperature at a low temperature, the rice may be spoiled at an early stage.

On the other hand, Japanese Patent Publication No. 57-1214 and Japanese Patent Application Laid-Open No. 57-9425 are provided with a lid heater for preventing dew condensation, but the lid heater depends on the heat retention temperature in the container. Because electricity is supplied regardless of the temperature, when the heat retention temperature increases and the temperature difference between the rice temperature and the lower surface of the lid decreases,
Steam condenses on the lower surface of the lid, and the condensed water drops on the upper surface of the rice, and the rice rots quickly. Conversely, when the heat retention temperature decreases and the temperature difference between the rice temperature and the lower surface of the lid increases,
There is a concern that the radiant heat from the lower surface of the lid may cause the upper surface of the rice to become too dry or yellow.

As described above, in all of the publications described above, sufficient consideration is not given to the condensation on the lower surface of the lid and the prevention of the drying and yellowing of the rice when the heat retaining temperature is changed.

To solve such a problem, Japanese Patent Laid-Open Publication No. Hei 5-56841 discloses a method in which an inner lid corresponding to the lower surface of a lid is heated and controlled by a lid heater. Slightly higher (about + 1 ° C) and slightly lower (about -3 ° C) than the warming temperature of rice (about 71 ° C)
The lid heater is controlled by the heating amount set to be a slightly higher temperature (approximately + 5 ° C), so that the heat retention state of rice can be selected according to changes in the ambient temperature and the amount of rice. An insulated kettle is disclosed.

[0007] However, in the insulated pot having the above-described configuration, the insulated temperature of rice is fixed, and the setting of the insulated temperature cannot be changed in accordance with the user's preference or use situation. Also,
The temperature of the inner lid can be set to a lower temperature than the temperature of rice by using the heat-retention selection switch.If the lid heater is controlled under these settings, condensation on the lower surface of the inner lid may be reduced. It raises concerns that it will be more pronounced.

Therefore, the present invention solves the above-mentioned problems and allows the heat retaining temperature to be arbitrarily set and changed according to the user's preference and usage conditions. An object of the present invention is to provide a rice cooker capable of reliably preventing dew condensation on the lower surface and preventing drying and yellowing of rice.

[0009]

A rice cooker according to the present invention comprises a container, container heating means for heating the container, and heat insulation control means for controlling the container heating means for keeping the container at a predetermined temperature. And a lid that covers the upper opening of the container,
Insulation temperature changing means capable of setting and changing the insulation temperature of the insulation control means in multiple stages, and the lower surface of the lid is set to a heating temperature higher than the insulation temperature of the insulation control means, and the insulation control means Even when the set value of the heat retention temperature is changed, a lid heating control means for keeping a temperature difference between the temperature of the rice in the container and the temperature of the rice facing portion on the lower surface of the lid substantially constant is provided.

[0010] According to the above configuration, since the heat retention temperature of the heat retention control means can be changed and set in multiple stages by the heat retention temperature change means, the heat retention temperature of the rice in the container can be arbitrarily set according to the user's preference and usage conditions. Settings can be changed. Also,
Even if the heat retention temperature of the rice in the container is changed, the temperature difference between the rice and the lower surface of the lid facing the upper surface of the rice is kept substantially constant, and the heating temperature of the lower surface of the lid is higher than the rice temperature. Since the control by the lid heating control means is performed, even if the heat retaining temperature is switched, dew condensation on the lower surface of the lid can be prevented, while the radiant heat from the lower surface of the lid makes the upper surface of the rice too dry or yellow. It can be prevented from changing. In addition, the temperature of the lower surface of the lid becomes higher than the temperature at which the temperature of the lid is kept at the time of keeping the temperature, so that the condensation of the dew on the lower surface of the lid can be reliably prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1 showing a cross-sectional view of a rice cooker, reference numeral 1 denotes a vessel main body having an open upper surface, and the vessel main body 1 includes an inner case 2 and an outer case 3, and a glass wool or the like is provided between the inner case 2 and the outer case 3. A heat insulating material 4 is provided. An aluminum reflector 5 is provided at the lowermost part in the inner case 2, and a bottomed cylindrical container 6 having an open upper surface is inserted into the inner case 2 at an upper portion of the reflector 5. It is removably housed. Reference numeral 7 denotes a lid, which is an outer lid 8 for opening and closing the upper opening of the container body 1.
And a lid frame 9 provided below the outer lid 8 and a lid lower plate 10 for directly opening and closing the upper opening of the container 6. A heat insulating material is provided between the outer lid 8 and the lid lower plate 10. Material 11 is provided. The lid 7 is rotatably supported by the container body 1 by a hinge 12 located on the right side in the figure, and is always urged in the opening direction by a spring 13 provided on the hinge 12. On the other hand, on the left side of the main body 1 in the figure, a clamp 14 which is engaged with and disengaged from the lid 7 and holds the lid 7 in a closed state against the bias of the spring 13 is axially mounted.

Above the reflection plate 5, a rice cooker 15 is provided below the container 6 as a container heating means for heating the container 6, and the rice cooker 15 is provided on the outer surface of the inner case 2 in the same manner. A body heater 16 is provided as heating means. Further, reference numeral 17 denotes a lid heater which is a lid heating means for heating the lid lower plate 10 which is the lower surface of the lid 7, which covers a cord-shaped heater or the like with aluminum foil, and is adhered and fixed to the upper portion of the lid lower plate 10. Be composed. When the lid 7 is closed, heat from the lid heater 17 is directly radiated into the container 6 via the lid lower plate 10.

Reference numeral 18 denotes a container sensor provided at the center of the lowermost part in the inner case 2 and serving as temperature detecting means for detecting the outer surface temperature of the container 6. The container sensor 18 has a built-in thermistor 20 in a heat-sensitive plate 19 that can move up and down. The heat-sensitive plate 19 is constantly urged upward by a coil spring 21 so as to press the outer lower surface of the container 6 in pressure. . Reference numeral 22 denotes a lid sensor which is a lid temperature detecting means composed of a thermosensitive element such as a thermistor.
It detects 10 temperatures. On the other hand, a code reel 24 around which a power cord 23 is wound is provided on the lower surface of the outer case 3. Reference numeral 25 denotes a circuit board located between the inner case 2 and the outer case 3 and provided on a side portion of the main body 1, and a control circuit unit 26 is mounted on the circuit board 25. Further, a unitized display operation panel 27 is provided on the upper side of the outer surface of the outer case 3.

FIG. 2 is a block diagram showing an electrical configuration.
Is a microcomputer constituting the control circuit unit 26, which is provided with storage means 32 such as a ROM and peripheral means such as a time measuring means 33 as is well known. The input side of the microcomputer 31 is connected to the container sensor 18 and the lid sensor 22 via input circuits 34 and 35, respectively.
Further, operation control means 36 using various switches provided in the display operation panel 27 is connected via an input circuit 37.
On the other hand, an output circuit is provided on the output side of the microcomputer 31.
The rice cooking heater 15, the body heater 16 and the lid heater 17 are connected via 38, 39 and 40, respectively.
A display means 41 such as an LED provided in the
Connected via Then, based on a sequence set in advance in the storage means 32, the power supply to the rice cooking heater 15, the body heater 16 and the lid heater 17 is turned on and off, and the display means
Display control for 41 is performed.

FIG. 3 shows a circuit diagram of a power supply section and a heater drive section. Reference numeral 51 denotes a power plug to which commercial AC power is supplied.
A power transformer 52 is connected between the two terminals.
A power supply voltage of V is supplied to the microcomputer 31.
A series circuit of the rice cooker 15 and the switching contact 54A of the relay 54, a series circuit of the body heater 16 and the triac 55, and a series circuit of the lid heater 17 and the triac 56 are provided between both ends of the power plug 51, respectively. Connected. The coil 54B of the relay 54 is connected to the microcomputer 31 via a relay drive circuit 57. According to an output signal from the microcomputer 31, only when the coil 54B is energized, the open / close contact 54A closes to cook rice. The heater 15 is energized and generates heat. The triacs 55 and 56 are connected to the microcomputer 31 via triac drive circuits 58 and 59, respectively, and individually control the power supply of the body heater 16 or the lid heater 17 according to an output signal from the microcomputer 31. . The power consumption of the rice cooker 15 is 113
0 W, the power consumption of the body heater 16 is 50 W, and the power consumption of the lid heater 17 is 50 W. The microcomputer 31
Is connected to the container sensor 18 and the lid sensor 22, and the rice cooker switch 60, the off switch 61, and the timer switch 62, which constitute the operation control means 36, are connected thereto. Further, 63 is a lid heating temperature selection switch which is a lid heating temperature selection means for setting a heating temperature of the lid lower surface plate 10 at the time of heat retention,
Numeral 64 denotes a heat-retention temperature selection switch as a heat-retention temperature changing means for setting the heat-retention temperature.
Connected to.

FIG. 4 is a block diagram showing the processing procedure of the control program during the heat-retention process stored in the storage means 32. In the figure, reference numeral 71 denotes an A / D converter connected to the container sensor 18 and constituting a part of the input circuit 34. The A / D converter 71 is provided with a resistor (not shown) for setting the heat retaining temperature of the container 6, and compares the set heat retaining temperature with the temperature detected by the container sensor 18 to control the heat retention. Output to 72. Insulation temperature selection switch 64 is A /
It is provided to vary the resistance value of the D converter 71. By operating the heat retention temperature selection switch 64, the set value of the heat retention temperature can be changed in eight steps every 1 ° C. within a range of 67 ° C. to 74 ° C. it can. Then, the heat retention control means 72 controls the power supply to the body heater 16 so as to keep the container 6 at the heat retention temperature set by the heat retention temperature selection switch 64.

On the other hand, reference numeral 73 denotes an A / D converter connected to the lid sensor 22 and constituting a part of the input circuit 35. This A
The / D converter 73 is provided with a resistor (not shown) for setting the heat retaining temperature of the lid lower plate 10, and the lid is set slightly higher than the heat retaining temperature set in the A / D converter 71. The heating temperature of lower surface plate 10 is compared with the temperature detected by lid sensor 22, and the result is output to lid heating control means 75. Further, the lid heating temperature selection switch 63 is provided to change the resistance value of the A / D converter 73. By operating the lid heating temperature selection switch 63, the heating temperature is increased by + 2 ° C. from the insulation temperature.
It can be set high in the range of from 9 to 9 ° C. And
The lid heating control means 75 controls the power supply to the lid heater 17 so that the lid lower surface plate 10 is maintained at the heating temperature set by the lid heating temperature selection switch 63.

Next, with the above configuration, each process of control from the start of rice cooking to the heat retention is described by the container sensor 18 and the lid sensor 22.
FIG. 5 is a graph showing the relationship between the temperature change and the heating pattern of each of the heaters 15, 16, and 17.

First, at the beginning of the rice cooking process, the rice is cooked for 8 minutes. In this one-side cooking, control is performed such that only the rice cooker 15 is energized for 3 minutes and then cut off for 5 minutes. Next, the process shifts to a substantial rice cooking process. At the beginning of the actual rice cooking, the rice cooker in the container 6 is heated by continuously energizing the rice cooker 15 and the body heater 16. When the detected temperature Tn of the container sensor 18 reaches a temperature close to 100 ° C. for a predetermined time, it is determined that the cooked food in the container 6 is in a boiling state, and the rice cooker 15 is turned on every 30 seconds. The power is cut off, and the amount of heating of the container 6 is reduced. Simultaneously with the detection of the boiling state, the power supply to the lid heater 17 is controlled at predetermined time intervals, and the body heater 16 is continuously energized. Thereafter, the detected temperature Tn of the container sensor 18 becomes about 12
When the cooking temperature set at 0 ° C. is reached, it is determined that the inside of the container 6 is in a dry-up state, and the rice cooking is shifted to the spotting process. In this spotting process, the rice cooker 15 is once turned off, and then turned on again for only 30 seconds. The body heater 16 is continuously energized until the end of the swing stroke. Further, the lid heater 17 detects the temperature T detected by the lid sensor 22.
If the detected temperature Tf is lower than 105 ° C., power is supplied, and if the detected temperature Tf is higher than 105 ° C., the power is cut off.
While maintaining the temperature in ° C., the generation of dew condensation water adhering to the lid lower plate 10 is prevented.

When the 15-minute squeezing process is completed, the process shifts to the warming process. In this warming-up process, normally, based on the detected temperature Tn of the vessel sensor 18, the body heater 16 is cut off and controlled by the warming control means 72 so that the warming temperature of the vessel 6 is kept at 71 ° C. When the detected temperature Tn is lower than 71 ° C., the body heater 16 is energized, and the detected temperature T
When n is 71 ° C. or higher, the body heater 16 is turned off. The heat retention temperature can be changed by operating the heat retention temperature selection switch 64 every 1 ° C. within a range of 67 ° C. to 74 ° C. On the other hand, the lid heating control means 75 controls the detection temperature Tf of the lid sensor 22 so that the heating temperature of the lid lower surface plate 10 is normally + 5 ° C. higher than the thermal insulation temperature of the thermal insulation control means 72.
Based on this, the power supply to the lid heater 17 is controlled. For example, when the heat retention temperature is set to 71 ° C., the lid heater 17 is energized when the detected temperature Tf of the lid sensor 22 is lower than 76 ° C., and when the detected temperature Tf is 76 ° C. or higher, the lid heater 17 is turned on. Is turned off and the temperature difference between the heating temperature of the lid lower surface plate 10 and the thermal insulation temperature is the same unless the lid heating temperature selection switch 63 is operated even when the set value of the thermal insulation temperature is changed by the thermal insulation temperature selection switch 64. Is held. Also, the lid heating temperature selection switch 63
By operating, the temperature difference between the heating temperature for the lid lower plate 10 and the heat retaining temperature of the container 6 can be changed in eight steps in increments of 1 ° C. within a range of +2 to + 9 ° C. according to preference. Further, the power-off control of the lid heater 17 by the lid heating control means 75 is performed after the heat retention control means 72 first energizes the body heater 16. In addition, the rice cooker 15 is always in a blackout state during the warming process.

As described above, according to the above-described embodiment, the heat-retention temperature of the heat-retention control means 72 can be set and changed in multiple stages by the heat-retention temperature selection switch 64 as the heat-retention temperature change means. Can be arbitrarily set and changed according to the temperature of the rice in the container 6. In addition, even when the heat retention temperature of the rice in the container 6 is changed, the temperature difference between the rice and the lid lower surface plate 10 facing the upper surface of the rice is kept substantially constant.
And, so that the heating temperature of the lid lower plate 10 is equal to or higher than the rice temperature,
Since the lid heating control means 75 controls the lid heater 17, the condensation on the lid lower surface plate 10 can be prevented even when the heat retention temperature is switched, while the radiant heat from the lid lower surface plate 10 causes Can be prevented from becoming too dry or yellowing. In addition, the temperature of the lid lower surface plate 10 becomes higher than the heat retaining temperature during the heat retention, and it is possible to reliably prevent condensation from adhering to the lid lower surface plate 10.

That is, a heat-retention temperature selection switch 64 that can change the heat-retention temperature of the heat-retention control means 72 in multiple steps, and a lid heater so that the lid lower surface plate 10 has a heating temperature higher than the heat retention temperature of the heat-retention control means 72. In addition to controlling the temperature control unit 17, even when the set value of the heat retention temperature of the heat retention control means 72 is changed, the lid heating for keeping the temperature difference between the rice temperature in the container 6 and the temperature of the rice facing part of the lid lower plate 10 constant. By providing the control means 75, it is possible to arbitrarily set and change the heat retaining temperature according to the user's preference and use conditions, and even when the heat retaining temperature is switched, the condensation on the lid lower surface plate 10 is surely prevented. It can prevent drying and yellowing of the rice.

Furthermore, even when the set value of the heat retention temperature is changed by the heat retention temperature selection switch 64, the temperature difference between the rice temperature in the container 6 and the rice facing portion of the lid lower plate 10 facing the upper surface of the rice is constant. Since the power cutoff control to the lid heater 17 is performed so as to keep the upper surface of the rice dry or yellow discolored, or without condensation of steam on the lid lower plate 10,
The same dry state can be maintained for the upper surface of the rice.

Further, since the temperature difference between the heating temperature of the lid lower plate 10 and the heat retaining temperature can be appropriately changed by the lid heating temperature selection switch 63, the drying state of the rice upper surface during the heat retaining time can be changed according to preference. It is possible to maintain the same dry state with respect to the upper surface of rice even when the actual rice temperature fluctuates due to room temperature fluctuations outside the rice cooker or differences in the amount of cooked rice.

Further, as an effect in the embodiment, since the heating of the lid lower plate 10 by the lid heater 17 is performed after the rice cooker 15 is turned off during the heat retaining process, the lid lower plate 10 is heated. In order to prevent dew water from adhering to the container 6, the risk that the upper surface of the rice in the container 6 is excessively dried can be eliminated.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, the setting conditions and the like in the heat retaining temperature changing means and the lid heating temperature selecting means may be appropriately changed in consideration of the heating capacity of each heater.

[0027]

The rice cooker of the present invention has a container, container heating means for heating the container, heat control means for controlling the container heating means for keeping the container at a predetermined temperature, and the container. A cover for covering the upper surface opening of the cover, a heat retention temperature changing means capable of changing the heat retention temperature of the heat retention control means in multiple steps, and a heating temperature of the lower surface of the lid being higher than the heat retention temperature of the heat retention control means. In addition, even when the set value of the heat retention temperature of the heat retention control means is changed, the lid heating that keeps the temperature difference between the rice temperature in the container and the temperature of the rice facing portion on the lower surface of the lid substantially constant. Control means, it is possible to arbitrarily change the setting of the heat retaining temperature according to the user's preference and use conditions, and even when the heat retaining temperature is switched, the heat retaining temperature to the lower surface of the lid body is reduced. Prevents condensation And it is possible to prevent the variable rice drying or yellow.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rice cooker showing one embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the same.

FIG. 3 is a circuit diagram of a power supply unit and a heater driving unit according to the first embodiment.

FIG. 4 is a block diagram of a main part of the above.

FIG. 5 is a graph showing each control process from the start of rice cooking to the heat retention.

[Explanation of symbols]

 6 container 7 lid 10 lid lower plate 15 rice cooker (container heating means) 16 body heater (container heating means) 64 insulation temperature selection switch (insulation temperature changing means) 72 insulation control means 75 lid heating control means

Claims (1)

(57) [Claims] 1. A container, container heating means for heating the container, heat insulation control means for controlling the container heating means for keeping the container at a predetermined temperature, and a lid for covering an upper opening of the container. The body and the heat retention temperature of the heat retention control means are multi-stage
Basis set and changeable retained temperature change means, together with the lid bottom surface is made to be a higher heating temperature than retained temperature of the heat keeping control means, when you change the set value of the retained temperature of the heat keeping control means And a lid heating control means for maintaining a temperature difference between the temperature of the rice in the container and the temperature of the rice-facing portion on the lower surface of the lid substantially constant.