JP3248810B2 - Insulation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat retaining device for keeping food in a pot hot, for example, by induction heating.

[0002]

2. Description of the Related Art For example, in Japanese Patent Application Laid-Open No. 5-42034, a heating means for performing induction heating is set at a fixed time interval, for example, 1 hour.
It is configured to perform a heat retaining operation by driving for about 1 second every 0 minutes. When the temperature of the pot is high immediately after the completion of rice cooking at the time of setting the heat retention, for example, the time interval for operating the heating means is switched from 10 minutes to 30 minutes.

[0003]

However, according to this publication, the heating means is operated at regular time intervals during the heat retention, so that when the input voltage to the heating means is low, the amount of heating is reduced. However, in some cases, there has been a problem that a predetermined heat retaining temperature cannot be maintained. In addition, when the rice in the pot is to be kept warm again, there is a problem that it takes a long time to reach the predetermined temperature.

[0004] These problems become even more remarkable when the outside air temperature is low or when the amount of heat retention is large. Therefore, the present invention can appropriately secure a heating amount corresponding to a decrease in the input voltage or a decrease in the outside air temperature even if there is a decrease in the input voltage or a decrease in the outside air temperature. It is an object of the present invention to provide a heat retaining device capable of appropriately securing a corresponding heating amount and performing a favorable heat retaining operation.

[0005]

SUMMARY OF THE INVENTION According to the present invention ,
Provided heat-resistant glass fiber-filled poly
An inner frame made of amide resin and a detachable
And the inside is made of aluminum material with excellent thermal conductivity,
Ferrite stainless steel that is hard to rust with magnetic metal material on the outside
A pot to keep warm the food in the two-layer structure constituted by the scan, the inner frame
Heating means arranged on the bottom outside for induction heating the pan, temperature detecting means for detecting the temperature of the pan, and heating means for a predetermined time
Predetermined time repeated induction heating operating a control to stop, and the temperature detecting means stop time interval of the induction heating operation time interval and the induction heating operation as the detected temperature of the pan is a number average heat amount as low due with induction heating operation And a heat retention control means for switching one or both of them.

[0006]

In the present invention having such a configuration, the heating means operates for a predetermined time and repeats the control of stopping the operation for a predetermined time. In this case, the lower the temperature of the pot, the larger the average heating amount. One or both of the operation time interval and the operation stop time interval are switched. As a result, the temperature of the pot is always maintained at an appropriate temperature.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a case in which the present invention is applied to a heat retaining function of a rice cooker will be described. FIG. 1 is a cross-sectional view showing the configuration of a rice cooker, in which a bottomed cylindrical non-metallic inner frame 2 is provided inside an outer frame 1 having a U-shaped cross section, and a rice cooker 3 is detachably mounted in the inner frame 2. It is provided freely. The inner frame 2 is made of, for example, a polyamide resin containing glass fiber having high heat resistance.

The rice cooker 3 has a two-layer structure in which the inside is made of an aluminum material having excellent thermal conductivity and the outside is made of a ferrous stainless steel which is made of a magnetic metal material and is hard to rust. The inner surface is coated with a non-adhesive PFA resin.

An induction coil 4 for induction heating the rice cooker 3 and a pan detection sensor 5 for detecting the presence or absence of the rice cooker 3 are arranged outside the bottom of the inner frame 2. In addition, a pot temperature sensor 6 for detecting the temperature of the rice cooker 3 is disposed at the center of the bottom of the inner frame 2 outside.

Inside the bottom of the outer frame 1, a circuit board 7 on which circuit elements of an induction heating circuit including an inverter circuit for driving the induction coil 4 are arranged. An intake port 8 is provided below the side of the outer frame 1, and a fan motor 9 is arranged inside the intake port 8 so that cooling air is taken in from the intake port 8.

A lid 10 is provided at the upper opening of the outer frame 1 so as to be openable and closable, and a lid temperature sensor 12 is disposed at a central portion on the upper surface side of a lower plate 11 of the lid 10. Is provided with a lid heater 13. An operation panel 1 provided with various operation switches and indicators on the outer surface of the lid 10.
4 are arranged.

FIG. 2 is a block diagram showing a circuit configuration.
Is a microprocessor provided with a control unit, a calculation unit, a clock unit, and a storage unit. The microprocessor 21 is connected to an input port 22 with an A / D conversion function and an output port 23.

The input port 22 is connected to an operation switch 24 of the operation panel 14, the pan temperature sensor 6, the lid temperature sensor 11, and the pan detection sensor 5, respectively. The output port 23 includes a heater driving unit 25 for the lid heater 13 and a motor driving unit 2 for the fan motor 9.
6. A display drive unit 28 for driving the display 27 of the operation panel 14 and a buzzer drive unit 30 for driving the buzzer 29 are connected respectively.

The output port 23 is connected to the high-frequency current adjusting section 32 of the induction heating circuit 31, and the high-frequency current adjusting section 32 is connected to the induction coil 4. The high-frequency current adjusting unit 32 is configured by an inverter circuit.

The induction heating circuit 31 supplies a predetermined high-frequency current to the induction coil 4 by the high-frequency current adjusting unit 32. As a result, an alternating magnetic field is generated in the induction coil 4.
At this time, if the rice cooker 3 is located at a predetermined position facing the induction coil 4, an eddy current is generated mainly in the magnetic metal material portion of the rice cooker 3, and the eddy current is converted into Joule heat. The pan 3 generates heat.

The pan detection sensor 5 includes the induction coil 4
The high-frequency current adjusting unit 32 that supplies the high-frequency current to the inverter circuit, that is, the input current to the inverter circuit is detected, and when the rice cooker 3 is not at a predetermined position with respect to the induction coil 4, the eddy current does not occur and the load current decreases. Therefore, the absence of the pan is detected by detecting the decrease in the load current.

At the time of cooking rice, the microprocessor 21
Drives and controls the induction heating circuit 31 to supply a predetermined high-frequency current to the induction coil 4, and to control the high-frequency current adjustment unit 3 based on the temperature detected by the pot temperature sensor 6 and the temperature detected by the lid temperature sensor 11.
2 is controlled.

After the rice cooking operation is completed and a predetermined steaming operation is performed, the operation shifts to a warming operation. At the time of keeping the temperature, the microprocessor 21 drives and controls the induction heating circuit 31 based on FIG.

First, at S1, the pot temperature sensor 6
It is checked whether the detected temperature is less than 72 ° C., and if the detected temperature is 72 ° C. or more, the operation of the induction heating circuit 31 is stopped in S2, that is, the induction heating off control is performed.

If the detected temperature is lower than 72 ° C., S
At 3, the operation of the induction heating circuit 31, that is, the induction heating ON control is performed. Then, when the count time in the timer section has elapsed for 2 seconds, induction heating off control is performed in S4. In this state, when 15 seconds have elapsed in the timer, it is checked in S5 whether the temperature detected by the pot temperature sensor 6 is 72 ° C. or higher.

If the detected temperature is equal to or higher than 72 ° C., the induction heating-off control is further continued for 10 seconds in S6, and it is checked again in S5 whether the temperature detected by the pan temperature sensor 6 is equal to or higher than 72 ° C. I do.

If the detected temperature is lower than 72 ° C., it is further checked in S7 whether the detected temperature of the pot temperature sensor 6 is lower than 70 ° C. And if it is 70 ° C or higher,
After performing the induction heating ON control for 2 seconds in S8, the induction heating OFF control is performed for 15 seconds in S9, and it is checked again whether the detected temperature of the pot temperature sensor 6 is 72 ° C. or more in S5. .

The temperature detected by the pan temperature sensor 6 is 7
If the temperature is lower than 0 ° C., the induction heating ON control is performed for 3 seconds in S10, then the induction heating OFF control is performed for 10 seconds in S6, and the detected temperature of the pot temperature sensor 6 is 72 in S5 again.
Check if it is above ℃.

In the embodiment having such a configuration, when the rice cooking operation and the steaming operation are completed, the operation is shifted to the heat retaining operation.
In the warming operation, first, it is checked whether the temperature of the rice cooker 3 is lower than 72 ° C. And the temperature of rice cooker 3 is 72 ℃
The operation of the induction heating circuit 31 is stopped until the temperature falls below the threshold. That is, induction heating off control is performed.

When the temperature of the rice cooker 3 drops below 72 ° C., the induction heating ON control is performed for 2 seconds, and then the induction heating OFF control is performed for 15 seconds. Thereafter, if the temperature of the rice cooker 3 is in a range of less than 72 ° C. to 70 ° C. or more, the induction heating on control for 2 seconds and the induction heating off control for 15 seconds are repeated and continued.

When the temperature of the rice cooker 3 becomes 72 ° C. or more, the induction heating off control is forcibly performed for 10 seconds. This is repeated unless the temperature of the rice cooker 3 becomes lower than 72 ° C. After all, the induction heating off control is continuously performed until the temperature of the rice cooking pot 3 becomes lower than 72 ° C.

If the temperature of the rice cooker 3 drops below 70 ° C., the on / off period of the induction heating is changed at this time. That is, induction heating ON control for 3 seconds and induction heating OFF control for 10 seconds are performed, and this is repeated until the temperature of the rice cooker 3 becomes 70 ° C. or higher.

Thus, the temperature of the rice cooker 3 is lower than 72 ° C.
When the temperature is in the range of 70 ° C. or more, the induction heating on control for 2 seconds and the induction heating off control for 15 seconds are repeated, but when the temperature of the rice cooker 3 becomes lower than 70 ° C., the induction heating on control for 3 seconds, The average heating amount is increased by changing the induction heating ON period and the induction heating OFF period such that the induction heating OFF control for 10 seconds is repeated.

Therefore, during the warming operation, when the input voltage drops and the temperature of the rice cooker 3 falls below 70 ° C., or when the temperature of the rice cooker 3 falls below 70 ° C. due to the low outside air temperature,
Since the average heating amount of the induction heating increases, the temperature of the rice cooker 3 can be prevented from lowering and the temperature of the rice cooker 3 can be maintained in a range of less than 72 ° C to 70 ° C or more.

When the temperature is kept low, the temperature of the rice in the rice cooker 3 is lowered once and the temperature is again kept in this state. When the rice is kept warm again in this state, the induction heating ON control for 2 seconds and the induction heating OFF control for 15 seconds are performed first. Is performed, the operation is switched to the induction heating on control for 3 seconds and the induction heating off control for 10 seconds, and the operation is repeated. In this case, too, the average heating amount of the induction heating increases, and the rice cooker The temperature of 3 is less than 72 ° C to 7
The time required to raise the temperature to 0 ° C. or higher can be shortened.

As described above, when the temperature of the rice cooker 3 drops below the predetermined heat retention temperature range of less than 72 ° C. to 70 ° C. or more, both the induction heating ON period and the induction heating OFF period are switched to reduce the average heating amount. Since the temperature is controlled so as to increase the temperature of the rice cooker 3 so as to always fall within a range of less than 72 ° C. to 70 ° C. or more, a favorable heat retaining operation can be performed.

In the above embodiment, to increase the heating amount, the induction heating on control for 2 seconds and the induction heating off control for 15 seconds are replaced with the induction heating on control for 3 seconds and the induction heating off control for 10 seconds. That is, the induction heating ON period is controlled so as to increase and the induction heating OFF period is decreased, but the present invention is not limited to this. For example, induction heating ON control for 5 seconds and induction heating OFF control for 20 seconds are performed. Even if the off period becomes long, the average heating amount may be increased.

In the above embodiment, both the induction heating ON period and the induction heating OFF period are switched to increase the heating amount. However, the present invention is not limited to this, and only one of them may be switched. In that case, when changing the induction heating ON period, control is performed so as to be longer, but when changing the induction heating OFF period, control may be performed so as to be shorter.

In this embodiment, the present invention has been described as applied to a heat retaining function of a rice cooker. However, the present invention is not necessarily limited to this, and a device dedicated to heat retaining may be used.

[0035]

As described above in detail, according to the present invention, one or both of the operation time interval and the operation stop time interval are switched so that the lower the detected temperature of the pot is, the larger the average heating amount becomes. Therefore, even if there is a drop in the input voltage or the outside air temperature, a heating amount corresponding to the drop can be secured appropriately. Can be appropriately secured, and a warming device capable of performing a favorable warming operation can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a block diagram of the embodiment.

FIG. 3 is a flowchart showing heat retention control by the microprocessor of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Cooking pot 4 ... Induction coil 6 ... Pot temperature sensor 21 ... Microprocessor 31 ... Induction heating circuit 32 ... High frequency current adjustment part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-130620 (JP, A) JP-A-3-112515 (JP, A) JP-A-5-146354 (JP, A) JP-A-5-130354 293037 (JP, A) JP-A-6-62954 (JP, A) JP-A-6-284962 (JP, A) JP-A-6-296547 (JP, A) JP-A-6-343545 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) A47J 27/00

Claims (1)

(57) [Claims] 1. A heat-resistant tube with a bottom provided inside an outer frame.
Frame made of polyamide resin with high glass fiber
And it is detachably provided in this inner frame, and the inside is thermally conductive
Made of excellent aluminum material, rust on the outside with magnetic metal material
A pot incubating the <br/> food a two-layer structure constituted by the beauty hard ferrite stainless, is placed at the bottom outside of the frame
Is a heating means for induction heating said pot, a temperature detecting means for detecting a temperature of the pot, a predetermined time the heating means induction
Predetermined time induction heating operation to repeatedly control to stop, and said temperature detecting means detects temperature downtime interval induction heating operation time interval and the induction heating operation as such that the average heat amount is larger lower pot by addition to heating operation A heat insulation control means for switching one or both of the heat insulation means.