JP3052527B2 - Jar 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 jar rice cooker mainly used at home and having a heat retaining function.

[0002]

2. Description of the Related Art In recent years, various efforts have been made for jar rice cookers with the aim of improving rice cooking performance. But,
Although the heat insulation performance of the jar function has not been studied much, measures against odor during heat insulation and yellowing of rice have become necessary as the need for long-time heat insulation increases.

[0003] The following describes the process of keeping the temperature of a conventional jar rice cooker. FIG. 6 shows a configuration of a conventional jar rice cooker. In FIG. 6, 1 is a pot for putting rice and water, 2
Is a heater for heating the pan 1, 3 is a temperature detecting means for detecting the temperature of the bottom of the pan 1, and 4 is a storage means for storing control temperature data including a heat retention control temperature for controlling the heater 2. ing. Reference numeral 5 denotes control means for controlling the heater 2 so that the temperature at the bottom of the pot 1 becomes a heat retention control temperature preset in the storage means 4 when the temperature is kept.

[0004] The operation of the conventional jar rice cooker having the above-described configuration will be described below. The control circuit 5 energizes the heater 2 when the temperature of the bottom of the pot 1 detected by the temperature detecting means 3 is lower than the heat retaining control temperature (about 71.5 ° C.) stored in the storage means 4 when the heat retaining step is started. When the temperature exceeds the heat retention control temperature, the power supply to the heater 2 is stopped and the pan 1 is not heated. By continuously performing this control operation, the temperature of the pan 1 is to be maintained at a constant temperature control temperature.

FIG. 7 shows the above operation, in which the amount of heating (energization time) by the heater 2 and the temperature at the bottom of the pot 1 detected by the temperature detecting means 3 are plotted on the vertical axis, and the time is plotted on the horizontal axis. taking it. In FIG. 7, it can be seen that the actual temperature at the bottom of the pot with respect to the heat retention control temperature point has a difference due to residual heat after the heater 2 is stopped, a delay in heat transfer when the heater 2 is turned on, and the like.

FIG. 8 shows the correlation between the temperature at the bottom of the pot 1 detected by the temperature detecting means 3 and the temperature of the rice in the pot and the room temperature in the conventional jar rice cooker constructed as described above. In FIG. 8, when the bottom of the pot is controlled at the temperature control temperature point, the lower the room temperature, the cooler the outer periphery of the pot, so that a temperature difference occurs between the bottom (outer periphery) of the pot and the rice (inside) in the pot. It can be seen that the temperature of the rice is higher than the temperature control temperature.

FIG. 9 shows the correlation between the heating time per 30 minutes of the heater and the room temperature. In FIG. 9, it can be seen that the lower the room temperature is, the cooler the outer periphery of the pot is, so that the energization ratio of the heater 2 is higher.

Next, a description will be given of the rice kept warm. The yellowing of the rice color rapidly progresses when the rice temperature exceeds a certain temperature (around 70 ° C.). In addition, the odor of rice becomes stronger when the temperature of the rice exceeds a certain temperature (around 70 ° C.) due to the decomposition of fatty acids contained in the rice by oxidative action. Conversely, when the temperature is low, the odor of rice grows due to the propagation of various bacteria. It has been found that the smell increases.

[0009]

However, in the above-described conventional configuration, as is apparent from FIG. 8, the difference between the temperature control temperature and the actual rice temperature is caused by the influence of the change in room temperature on the temperature detecting means. However, there is a problem in that

The present invention solves the above-mentioned conventional problems, and reduces the influence of a change in room temperature on temperature detecting means.
It is an object of the present invention to provide a jar rice cooker that keeps the temperature of rice in a pot constant.

[0011]

Means for Solving the Problems To achieve this object, a jar rice cooker according to the present invention according to claim 1 comprises a pot for putting rice and water, and a heating means for heating the pot. A temperature detecting means for detecting the temperature in the pot, a storage means for storing a plurality of heat-retention control temperatures for controlling the heating means, and a predetermined time after starting the time keeping after shifting to the heat retention step The first timer means, the second timer means which starts counting after receiving the output of the first timer means and outputs the result at a predetermined time, and the second timer means which receives the output of the first timer means. Measuring and outputting the heating time of the heating means until the output of the second timer means is received from the third timer
A timer means, and a timer of the first timer means is started at the time of shifting to the heat retaining step, and the temperature of the pot is selected from among the heat retaining control temperatures stored in the storage means at the time of the heat retaining. Controlling the heating means so that
After receiving the output of the second timer means, the control means selects the heat retention control temperature stored in the storage means based on the output of the third timer means, and selects the first timer means and the second timer means. Control means for initializing the time measurement content of the third timer means and starting time measurement of the first timer means.

Further, in order to achieve this object, in a jar rice cooker according to the present invention as set forth in claim 2, the control means causes the first timer means to start timing at the time of shifting to the warming step. The heating means is controlled so that the temperature of the pot becomes a pre-selected heat-retention control temperature among the heat-retention control temperatures stored in the storage means at the time of the heat retention, and the output of the second timer means is received. Thereafter, the control unit selects the heat retention control temperature stored in the storage means based on the output of the third timer means. If the selected heat retention control temperature is different from the previously selected heat retention control temperature, the first heat retention control temperature is determined. The timer means, the second timer means, and the third timer means are initialized, and the first timer means is started, and the heat control temperature is the same as the previously selected heat control temperature. If It has a configuration which starts clocking the serial second timer means and the third said clocking time of the timer means and initializes the second timer means of the third timer means.

[0013]

According to the construction of the first means, the control means controls the heating means so that the temperature of the bottom of the pot becomes a predetermined heat keeping control temperature after entering the heat keeping step, and the predetermined time elapses by the first timer means. Until the change of the heat retention control temperature is prohibited, after that, when a predetermined time has elapsed by the second timer means, the heat retention control temperature corresponding to the heating time of the heating means measured by the third timer means is stored in the storage means. At the same time as selecting from the heat retention control temperature, the timer contents of the first timer means, the second timer means, and the third timer means are initialized. It is possible to make the temperature of the rice close to the constant temperature by correcting the temperature control temperature at the bottom of the pot at regular intervals.

Further, according to the configuration of the second means, the control means controls the heating means so that the temperature of the bottom of the pot becomes a predetermined heat keeping control temperature after entering the heat keeping step, and the predetermined time is controlled by the first timer means. The change of the heat retention control temperature is prohibited until the time has elapsed, and thereafter, when a predetermined time has elapsed by the second timer means, the heat retention control temperature corresponding to the heating time of the heating means measured by the third timer means is stored. At the same time as selecting from the heat retention control temperatures stored in the first timer means and the second timer means when the selected heat retention control temperature is different from the heat retention control temperature selected last time. The time measurement of the third timer means is initialized and the time measurement of the first timer means is started. Conversely, if this heat retention control temperature is the same as the previously selected heat retention control temperature, the second Since the timers and the third timer are initialized and the second timer and the third timer are started, if the heating time does not change, the heating time is continuously increased. If there is a change in the temperature of the rice, the temperature of the rice is kept constant by compensating the temperature control of the bottom of the pot based on the change of the heating time due to the change of the room temperature and the change of the temperature control by having a certain prohibition time. Temperature can be approached.

[0015]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a pot for putting rice and water, 12 is a heater for heating the pot 11, 13 is a temperature detecting means for detecting the temperature of the bottom of the pot 11, and 14 is a control for the heater 12. Storage means for storing a plurality of heat-retention control temperatures, a first timer means for starting timekeeping after shifting to the heat-retention step and outputting a predetermined time, and a storage means 16 for the first timer means 15 The second timer means 17 which starts counting time after receiving the output and outputs the signal at a predetermined time is provided between the time from receiving the output of the first timer means 15 and the time of receiving the output of the second timer means 16. A third timer means 18 for measuring and outputting the heating time of the heater 12 is a control means, which starts the time measurement of the first timer means 15 at the time of shifting to the warming step, and stores the temperature at the time of keeping the temperature of the bottom of the pan 11 at the warming time. Stored in the means 14 The heater 12 is controlled so as to be a pre-selected heat retention control temperature among the heat retention control temperatures, and the output of the third timer means 17 is received after receiving the output of the second timer means 16. The selected heat retention control temperature is selected from the heat retention control temperatures stored in the storage means 14, and the time measurement contents of the first timer means 15, the second timer means 16, and the third timer means 17 are initialized. The timer of the first timer means 15 is started.

FIG. 2 is a specific circuit diagram of a jar rice cooker according to the first and second embodiments of the present invention.
In FIG. 2, reference numeral 20 denotes an AC power supply.
A series circuit of a heater 21 for heating the pan 11 to 0 and a relay contact 22 is connected, and the relay contact 22 is opened and closed by passing a current to a relay coil 25 via a transistor 24 by a signal from an output port of a microcomputer 23. It is configured as follows. Reference numeral 26 denotes a power supply of the microcomputer 23. Reference numeral 27 denotes a thermistor for detecting the temperature at the bottom of the pan 11, which is connected to an A / D converter 28 and inputs data to the microcomputer 23. Reference numeral 29 denotes a switch for starting cooking rice and terminating heat retention. A microcomputer 23 controls rice cooking and heat retention.

The operation of the jar rice cooker configured as described above will be described with reference to the flowchart of FIG. When the switch 29 is pressed, the microcomputer 23 controls the rice cooking, and after the rice cooking is completed, proceeds to step 31 to start keeping the temperature. First, in step 32, the heat retention control temperature is set to 72 ° C. in the heat retention temperature stored in the storage means 14.
In step 33, the time T1 of the first timer means 15 and the time T2 of the second timer means 16 are compared with the third time.
The timer time 17 of the timer means 17 is initialized, and the time T1 is measured by the first timer means 15 in step 34. In step 35, the temperature of the bottom of the pan 11 is input by the thermistor 27, and it is determined whether or not the input temperature exceeds 72 ° C.
1 so as to be energized, and proceed to step 38. If the input temperature exceeds 72 ° C. in step 35, control is performed in step 37 to cut off the power supply to the heater 21, and the process proceeds to step 38. In step 38, the first timer means 1
It is determined whether or not the counted time T1 of 5 has reached 30 minutes. If not, the process proceeds to step 39. In step 39, it is determined whether or not the switch 29 has been pressed. If so, the process proceeds to step 51, and if not, the process returns to step. Steps 34 to 39 are repeated if the time T1 of the first timer means 15 is within 30 minutes from the start of the heat retention and the switch 29 is not pressed. If the time T1 of the first timer means 15 has reached 30 minutes in step 38, the process proceeds to step 40. In step 40, the time T2 is measured by the second timer means 16. In step 41, the temperature of the bottom of the pan 11 is input by the thermistor 27, and it is determined whether or not the input temperature exceeds 72 ° C. If not, control is performed so that the heater 21 is energized in step 42. The energization time T2 of the heater 21 is measured by the third timer means 17, and the routine proceeds to step 45. If the input temperature exceeds 72 ° C. in step 41, control is performed in step 44 to cut off the power supply to the heater 21, and the process proceeds to step 45. Step 45
Then, it is determined whether or not the counted time T2 of the second timer means 16 has reached 30 minutes. In step 46, it is determined whether or not the switch 29 has been pressed. If so, the process proceeds to step 51; otherwise, the process returns to step 40. If the time T2 of the second timer means 16 is within 30 minutes and the switch 29 is not pressed, the steps 40 to 46 are repeated.
If the counted time T2 of the second timer means 16 has reached 30 minutes in step 45, the flow advances to step 47, and
Now, the energization time T3 of the heater 21 measured in step 43
Is longer than 10 minutes, at step 48, 7 of the heat retention temperatures stored in the storage means 14 as the heat retention control temperature.
Select 0 ° C. and go to step 50. If the energization time T3 of the heater 21 is less than 10 minutes in Step 47, 72 ° C is selected from the heat retention temperatures stored in the storage means 14 as the heat retention control temperature in Step 49, and the process proceeds to Step 50. In step 50, it is determined whether or not the switch 29 has been pressed. If so, the process proceeds to step 51; otherwise, the process returns to step 33. In step 51, the process proceeds to the next step such as canceling the heat retaining step.

As described above, according to the jar rice cooker according to the embodiment of the present invention, the electric power is controlled so that the temperature of the bottom of the pot enters the heat retaining step so as to become the heat retaining control temperature (72 ° C.). Since the time increases (see FIG. 7), if the length of the energization time is 10 minutes or more per 30 minutes, it is detected that the room temperature is low. If the room temperature is low, the temperature of the rice becomes higher than the heat retention control temperature (see FIG. 8), so the setting of the heat retention control temperature is lowered (changed from 72 ° C. to 70 ° C.). Furthermore, when the temperature setting of the heat retention control is reduced from 72 ° C. to 70 ° C., the power is not supplied until the temperature at the bottom of the pot drops to 70 ° C. Therefore, the power supply time is maintained for 30 minutes after the temperature setting of the heat retention control is lowered even if the room temperature is low. Since it becomes shorter (less than 10 minutes) and erroneously detects that the room temperature is high, the first timer means, the second timer means, and the third timer means are initialized after selecting the heat retention control temperature, and the electricity is supplied for 30 minutes. The heat retention control temperature is selected as needed as one cycle of the time counting prohibition period and the 30 minute conduction time counting period. From the above operation, the effect of the room temperature on the thermistor is reduced because the temperature control temperature is changed at a constant cycle with respect to the change in the room temperature while the temperature is maintained, and the actual rice temperature is kept close to the constant temperature (73 ° C.). Can be kept.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

In FIG. 4, 11 is a pot for putting rice and water, 12 is a heater for heating the pot 11, 13 is a temperature detecting means for detecting the temperature of the bottom of the pot 11, and 14 is a control for the heater 12. Storage means for storing a plurality of heat-retention control temperatures, a first timer means for starting timekeeping after shifting to the heat-retention step and outputting a predetermined time, and a storage means 16 for the first timer means 15 The second timer means 17 which starts counting time after receiving the output and outputs the signal at a predetermined time is provided between the time from receiving the output of the first timer means 15 and the time of receiving the output of the second timer means 16. The third timer means for measuring and outputting the heating time of the heater 12 is the same as that shown in FIG. 1 is different from the configuration of FIG. 1 in that the control means 18 is controlled by the first timer
And the heater 12 is controlled so that the temperature at the bottom of the pan 11 becomes a pre-selected heat control temperature among the heat control temperatures stored in the storage means 14 during the heat preservation. After receiving the output of the second timer means 16, a heat retention control temperature corresponding to the output of the third timer means 17 is selected from the heat retention control temperatures stored in the storage means 14. If the temperature is different from the previously selected temperature control temperature, the contents of the first timer means 15, the second timer means 16, and the third timer means 17 are initialized and the first timer means 1 is reset.
5 is started. Conversely, if this heat retention control temperature is the same as the previously selected heat retention control temperature, the contents of the second timer means 16 and the third timer means 17 are initialized and the second The point is that the second timer means 16 and the third timer means 17 start timing.

The operation of the jar rice cooker configured as described above will be described with reference to the flowchart of FIG. If the switch 29 is pressed, the microcomputer 23 performs rice cooking control, and after the rice cooking is completed, proceeds to step 61 to start keeping the temperature. First, in step 62, the timer time T1 of the first timer means 15, the timer time T2 of the second timer means 16 and the timer time T3 of the third timer means 17 are initialized, and in step 63, the heat retention control temperature is stored in the storage means 14. Is set to 72.degree. C. among the heat retention temperatures stored in the storage unit, and the time T1 is measured by the first timer means 15 in step 64. In step 65, the temperature of the bottom of the pan 11 is input by the thermistor 27, and it is determined whether or not the input temperature exceeds 72 ° C.
1 so as to be energized and proceed to step 68. If the input temperature exceeds 72 ° C. in step 65, control is performed in step 67 to cut off the power supply to the heater 21, and the process proceeds to step 68. In step 68, the first timer means 1
It is determined whether the counted time T1 of 5 has reached 30 minutes. If not, the process proceeds to step 69. In step 69, it is determined whether or not the switch 29 has been pressed. If so, the process proceeds to step 85; otherwise, the process returns to step 64. If the time T1 of the first timer means 15 is within 30 minutes from the start of the heat retention and the switch 29 is not pressed, steps 64 to 69 are repeated. If the time T1 of the first timer 15 has reached 30 minutes in step 68, the process proceeds to step 70. In step 70, the time T2 is measured by the second timer 16. In step 71, the temperature of the bottom of the pot 11 is input by the thermistor 27, and it is determined whether or not the input temperature exceeds 72 ° C. If not, control is performed so that the heater 21 is energized in step 72. The third timer means 17 measures the energization time T2 of the heater 21 and proceeds to step 75. If the input temperature exceeds 72 ° C. in step 71, control is performed in step 74 to cut off the power supply to the heater 21, and the process proceeds to step 75. Step 75
Then, it is determined whether or not the counted time T2 of the second timer means 16 has reached 30 minutes. In step 76, it is determined whether or not the switch 29 has been pressed. If the switch 29 has been pressed, the process proceeds to step 85, and if not, the process returns to step 70. If the time T2 of the second timer means 16 is within 30 minutes and the switch 29 is not pressed, the steps 70 to 76 are repeated.
If the counted time T2 of the second timer means 16 has reached 30 minutes in step 75, the flow advances to step 77, and
Now, the energization time T3 of the heater 21 measured in step 73
Is longer than 10 minutes, at step 78, 7 of the heat retention temperatures stored in the storage means 14 as the heat retention control temperature.
Select 0 ° C. and go to step 80. If the energization time T3 of the heater 21 is less than 10 minutes in Step 77, 72 ° C. is selected from the heat retention temperatures stored in the storage means 14 as the heat retention control temperature in Step 79, and the routine proceeds to Step 80. In step 80, the heat retention control temperature selected this time in the steps from step 77 to step 79 is set to step 77.
It is determined whether or not the temperature is the same as the heat retention control temperature selected before the step. In step 81, it is determined whether or not the switch 29 has been pressed. If the switch 29 has been pressed, the process proceeds to step 85. If not, the process proceeds to step 82. In step 82, the time T1 of the first timer 15 and the second timer The 16 time counting time T2 and the time counting time T3 of the third timer means 17 are initialized, and the process returns to step 64. If the heat retention control temperature selected this time in step 80 is the same as the heat retention control temperature selected before the step 77, the process proceeds to step 83. In step 83, the timer time T2 of the second timer means 16 and the third Initialize the time T3 of the timer means 17 of step 84.
Proceed to. In step 84, it is determined whether or not the switch 29 has been pressed. If the switch 29 has been pressed, the process proceeds to step 85. If not, the process returns to step 70. In step 51, the process proceeds to the next step such as canceling the heat retaining step.

As described above, according to the jar rice cooker according to the second embodiment of the present invention, the electric power is controlled so that the temperature of the bottom of the pot enters the heat retaining step so as to become the heat retaining control temperature (72 ° C.). Since the energization time of the heater is extended (see FIG. 7), if the length of the energization time is 10 minutes or more per 30 minutes, it is detected that the room temperature is low. If the room temperature is low, the temperature of the rice is higher than the heat retention control temperature (see FIG. 8), so the setting of the heat retention control temperature is lowered (changed from 72 ° C. to 70 ° C.).
When the setting of the heat retention control temperature is reduced from 72 ° C to 70 ° C, power is not supplied until the temperature at the bottom of the pot drops to 70 ° C, so the power supply time is short for 30 minutes after the setting of the heat retention control temperature is lowered even if the room temperature is low. (Less than 10 minutes), the first timer means, the second timer means, and the third timer means are initialized after selecting the heat retention control temperature, and the energizing time for 30 minutes is selected. Establish a timekeeping prohibition period and then 30
The heat retention control temperature is selected at any time, with the minute being the energization time timing period. Further, when no change in the room temperature is observed (in the embodiment, when the room temperature is high and the length of energization time of the heater is 10 minutes or less per 30 minutes), the selected value of the heat retention control temperature is not changed (72). Since the change in the heat retention control temperature does not affect the heater energization time, only the second timer means and the third timer means are initialized after the heat retention control temperature is selected, and the energization time is set to the next 30 minutes immediately. The heat retention control temperature is selected at any time as the timing period. From the above operation, the effect of the room temperature on the thermistor is reduced because the temperature control temperature is changed more quickly with respect to the change in the room temperature while the temperature is maintained.
The actual temperature of the rice can be kept near a constant temperature (73 ° C.).

In this embodiment, a heater is used as the heating means. However, an induction heating coil, a gas combustor, or a heating means combining a heater and an induction heating coil may be used.
In short, any heating means for keeping the temperature may be used.

[0025]

As is apparent from the above embodiments, according to the first aspect of the present invention, the influence of the change of the room temperature on the temperature detecting means at a fixed period is reduced, and the temperature of the rice in the pan is kept at a predetermined temperature. The odor and yellowing of rice during warming can be reduced.

According to the second aspect of the present invention, the influence of the change in the room temperature on the temperature detecting means is prevented while preventing the erroneous determination due to the influence on the energization time of the heater when the temperature of the heat retention control is changed only when the room temperature changes. Since the temperature is reduced and controlled so that the temperature of the rice approaches a predetermined temperature, the odor and yellowing of the rice during the long-time heat retention can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a jar rice cooker according to a first embodiment of the present invention.

FIG. 2 is a specific circuit diagram of a jar rice cooker according to the first and second embodiments of the present invention.

FIG. 3 is a flowchart showing the operation of the microcomputer of the jar rice cooker according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a jar rice cooker according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the microcomputer of the jar rice cooker according to the second embodiment of the present invention.

FIG. 6 is a block diagram of a conventional jar rice cooker.

FIG. 7 is a diagram showing a heat retaining operation of a conventional jar rice cooker.

FIG. 8 is a diagram showing the correlation between the rice temperature and the pot bottom temperature and the room temperature during the warming process of a conventional jar rice cooker.

FIG. 9 is a diagram showing a correlation between the heating time of a pot by a heater and the room temperature during the heat retaining process of a conventional jar rice cooker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Pot 12 Heater 13 Temperature detection means 14 Storage means 15 1st timer means 16 2nd timer means 17 3rd timer means 18 Control means 23 Microcomputer

Continuation of the front page (56) References JP-A 63-52523 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A47J 27/00 109

Claims (2)

(57) [Claims] 1. A pot for putting rice and water, a heating means for heating the pot, a temperature detecting means for detecting the temperature of the pot, and a plurality of heat retention control temperatures for controlling the heating means. Storage means, and first timer means for starting time measurement after shifting to the heat retaining step and outputting at a predetermined time,
Second timer means for starting time measurement after receiving the output of the first timer means and outputting at a predetermined time; and receiving the output of the first timer means for controlling the output of the second timer means. Third timer means for measuring and outputting the heating time of the heating means until receiving the first heating means;
Start the timing of the timer means, and control the heating means so that the temperature of the pot becomes a pre-selected heat control temperature among the heat control temperatures stored in the storage means during the heat preservation, After receiving the output of the second timer means, select the heat retention control temperature stored in the storage means by the output of the third timer means, and select the first timer means, the second timer means, A jar rice cooker comprising: control means for initializing the time measurement content of a third timer means and starting the time measurement of the first timer means. 2. The control means starts the timing of the first timer means at the time of shifting to the heat retaining step, and the temperature of the pan is selected in advance from the heat retention control temperatures stored in the storage means at the time of heat retention. Controlling the heating means so that the temperature becomes the heat retention control temperature, and selecting the heat retention control temperature stored in the storage means by the output of the third timer means after receiving the output of the second timer means. If the selected temperature control temperature is different from the previously selected temperature control temperature, the first timer means, the second timer means, and the third timer means are initialized, and The timer of the first timer means is started, and if this heat retention control temperature is the same as the heat retention control temperature selected last time, the contents of time measurement of the second timer means and the third timer means are initialized and the second timer means is initialized. 2 timer hands Rice cooker of claim 1, wherein for starting counting of the third timer means and.