JPH0739456A - Heating method for rice cooker - Google Patents

Abstract

PURPOSE:To perform good rice cooking by determining the quantity of rice to be cooked from the temperature change of a rice cooking pot from the start of cooking rice to the temperature where the rice is impasted, setting the heating value after that according to the determined quantity of rice to be cooked to heat until boiling, correcting the quantity of rice to be cooked according to a temperature rise rate of the lower surface of a cover, and heating according to the corrected quantity of rice to be cooked. CONSTITUTION:A rice cooking pot 5 is stored inside an inner frame 4 in a rice cooker main body 1 where a cover 2 is installed on the upper opening. Induction heating coils 5 are disposed at the bottom of the inner frame 4 and below the sides thereof. Temperature sensors 8 and 12 are fitted to the side of the lower surface plate 10 of the rice cooking pot 5, and the cover 2 is provided with a vapor port 14. An electric current is applied to the induction heating coils 6 to cook rice with plenty of water the quantity of rice to be cooked is determined from the temperature change of the rice cooking pot to the temperature where the rice is impasted, and the heating value is preset to heat until boiling. The quantity of rice cooked is corrected according to a temperature rise rate of the lower surface of the cover 2 with the generation of vapor at the initial stage of boiling, and according to the corrected quantity of rice cooked, heating after boiling is performed. Thus, rice can be cooked correctly upto its tasty state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heating a rice cooker.

[0002]

[Prior Art] When rice is cooked with a normal rice cooker, rice is cooked by adding rice and water according to the amount of rice to a rice cooker. Since it is possible to cook better rice by changing it, recently, hot-boiled rice is cooked at the beginning of rice cooking, that is, heating and stopping is performed at a temperature below about 60 ° C, which is the temperature at which rice gelatinizes, and during that hot-water cooking. The amount of cooked rice is determined by detecting the temperature change of the rice cooker, and the boiling amount and the heating amount after boiling are set based on the determined amount of cooked rice.

[0003]

However, the heating amount after boiling is set based on the amount of cooked rice determined during the hot-pot cooking in this way. If foreign substances such as rice grains or dust are sandwiched between and, the temperature detection accuracy of the sensor decreases, or if the temperature detection accuracy of the sensor decreases due to deformation of the heat-sensitive part or pan of the sensor, an error occurs in the determination of the amount of cooked rice, As a result, there are problems such as insufficient heating in heating after boiling or excessive heating.

Therefore, in the present invention, the amount of cooked rice is determined by the temperature change of the rice cooker until the temperature at which the rice gelatinizes, and the amount of heat after boiling can always be set appropriately.
Provided is a method for heating a rice cooker that enables excellent rice cooking.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a rice cooker and a heating means for heating the rice cooker are provided in a rice cooker main body having an open upper part, and a lid is provided on the upper part of the rice cooker main body so as to be openable and closable. When rice is cooked with a rice cooker, the amount of cooked rice is judged by the temperature change of the rice cooker until the temperature at which the rice gelatinizes after starting rice cooking, and the heating amount of the heating means thereafter is determined based on this judgment result. Set the amount of rice cooked to the boiling point with this set amount of heating, correct the amount of cooked rice determined according to the rate of temperature rise on the lower surface of the lid accompanying the steam generation in the initial stage of boiling, and heat according to the corrected amount of cooked rice. The purpose is to heat after boiling in a certain amount. As a result, even if there is an error in the determination of the first cooked rice amount, the cooked rice can always be continued with an appropriate heating amount after boiling.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In addition, this Example describes what applied this invention to the electromagnetic induction heating type rice cooker. FIG. 1 is a cross-sectional view showing a main configuration of an electromagnetic induction heating type rice cooker. Reference numeral 1 is a rice cooker main body having an upper opening, and 2 is a lid body provided on the upper portion of the main body 1 so as to be openable and closable.

The rice cooker body 1 includes an outer frame 3 exposed to the outside and an inner frame 4 provided inside the outer frame 3 with a desired space therebetween. The inner frame 4 has a bottomed cylindrical shape made of heat-resistant PPS, glass-filled nylon (6PA), or the like, and a rice cooking pot 5 is detachably accommodated therein.

An electromagnetic induction heating coil 6 composed of a litz wire is arranged outside the center of the bottom portion of the inner frame 4 and outside the bottom portion of the inner frame 4 so as to extend from the side portion to the bottom portion by fixing with a silicone adhesive or the like. The heating coil 6 is surrounded and protected by a coil base 7 made of glass-filled PET or the like.

Although not shown, a ferrite rod made of a main raw material of iron oxide and a sintered material having a high magnetic permeability is attached to the outer surface of the coil base 7 by an adhesive agent so that the leakage magnetic flux from the heating coil 6 is external. To prevent it from being released.

The rice cooker 5 has an inner surface clad with a magnetic metal material layer composed of an aluminum layer having excellent heat conductivity and an outer surface layer of a ferritic stainless steel layer, and the inner surface thereof is coated mainly with PFA resin. To ensure non-adhesiveness.

A pan temperature sensor 8 is attached to the side surface of the inner frame 4 so that the heat-sensitive portion comes into contact with the outer surface of the rice cooking pot 5. Further, the pan temperature sensor 8 is provided on the side surface of the inner frame 4.
The body heater 9 is bonded and fixed to the upper side of.

The lid 2 is a bottom plate 1 that contacts the inner space of the pot.
The lid temperature sensor 11 for detecting the temperature of the lower surface of the lid is attached to the back side of the lower surface plate 10. Further, a lid heater 12 is adhesively fixed to the back side of the lower surface plate 10.

The lower plate 10 is made of an aluminum material containing a large amount of Fe component, which has good thermal conductivity, and has a milky white color by alumite treatment. That is,
Alumite treatment with a film thickness of about 20 μm to 25 μm is applied,
The surface treatment is performed so that the interference of the light of the alumina layer produces a milky white color.

The lid 2 is provided with an operation panel 13 exposed to the outside and provided with various operation switches and a display unit. Further, the lid 2 is provided with a steam port 14 for letting the steam accumulated inside escape to the outside.

An induction heating device 1 is provided inside the bottom of the outer frame 3.
5 is stored. Although not shown, other control circuits are incorporated and housed on the circuit board inside the side portions of the outer frame 3.

FIG. 2 is a block diagram showing a circuit portion, and 21 is a control circuit composed of a microprocessor or the like. The control circuit 21 has an input circuit 23 for controlling input of signals from the induction heating device 15 and various operation switches 22,
A heater drive circuit 24 including a triac (product name) for controlling ON / OFF of the pan temperature sensor 8 and the lid temperature sensor 11, an ON / OFF control of the body heater 9 and the lid heater 12, and a display drive circuit 26 for driving and controlling the display unit 25. , A memory 27, and a clock circuit 28 for counting the date and time are respectively connected.

The induction heating device 15 comprises a high frequency current generating circuit 29 and an output adjusting section 30 for adjusting the high frequency current amount from the high frequency current generating circuit 29 and supplying it to the induction heating coil 6. That is, the output adjusting unit 30 adjusts the amount of high-frequency current supplied to the induction heating coil 6 in the range of 50 to 100%, and also turns the output on and off.

The heating operation by the induction heating coil 6 is as follows.
When a high frequency current flows through the heating coil 6, an alternating magnetic field is generated in the heating coil 6, and an eddy current is generated mainly in the ferrite stainless layer of the rice cooking pot 5 facing the heating coil 6, and the eddy current causes Joule heat to cook the rice. This is done by heating the pot 5.

The operation panel 13 has various operation switches 22 such as a rice cooking switch for starting a rice cooking operation, a heat retaining switch for starting a heat retaining operation, a timer switch for starting a timer operation, and a switch for stopping each operation of rice cooking, heat retaining, and a timer. A switch etc. are provided.

Further, the display unit 25 of the operation panel 13 displays a rice cooking lamp for indicating that rice is being cooked, a heat retaining lamp for indicating that the rice is warming, a timer lamp for indicating that a timer is operating, a current time and a timer rice cooking time. A liquid crystal display etc. for displaying the time when rice is cooked are provided.

The control circuit 21 controls the hot rice cooked by hot-water cooking, main rice cooking, mourishing, and heat retention. The first hot-water cooking is controlled based on the flow chart of FIG. That is, the induction heating device 15 is controlled so that the induction heating output is 80%.
Turn on for 3 minutes. Then, the induction heating output is turned off for 6 minutes.

Then, the amount of cooked rice is judged from the amount of decrease in the temperature detected by the pan temperature sensor 8 in 6 minutes after the induction heating output is turned off, that is, the temperature difference A. That is, A ≧ 10K
If there is a large amount of rice, it is judged to be a large amount, if 10K> A ≧ 3K, it is judged to be a medium amount, and if A <3K, it is judged to be a small amount.

Subsequently, the induction heating output is turned on for 4 minutes, and then the induction heating output is turned off for 7 minutes. The induction heating output at this time is turned on at an output of 80% when the amount of cooked rice is large, turned on at an output of 70% when the amount of rice is medium, and turned on at an output of 60% when the amount of rice is small.

When the hot-water cooking for 20 minutes is completed in this way, the main rice cooking is subsequently performed. In this hot water cooking, the temperature of the rice cooking pot 5 is kept at a temperature lower than about 60 ° C. at which the rice is gelatinized.

The main rice cooking is controlled based on the flow chart shown in FIG. That is, when the amount of cooked rice is large, the induction heating output is 100.
%, The medium amount turns on at 90% induction heating output, and the small amount turns on at 70% induction heating output. In this state, it is checked that the temperature detected by the pan temperature sensor 8 is 80 ° C or higher and the temperature detected by the lid temperature sensor 11 is 85 ° C or higher.

When the temperature condition satisfying this condition is reached, the induction heating output is turned off for a large amount of rice for 2 minutes, for a medium amount of 2.5 minutes, and for a small amount of 3 minutes. This is done for the purpose of promoting the water absorption of rice during the boiling period.

Then, the induction heating output is turned on again. At this time, the rice is turned on at a large amount of 70%, a medium amount of 65%, and a small amount of 60%. In this state, the lid temperature sensor 1
Check that the detection temperature rise of 1 is below 2 ° C / 2 minutes. Under this condition, boiling is detected.

At this time, the temperature detected by the lid temperature sensor 11 is 9
Check time B from 0 ° C to boiling temperature. Then, based on the result of time B, the amount of cooked rice determined during hot water cooking is corrected. For example, if the time B may exceed 3 minutes when the amount of cooked rice is judged to be small, the amount of cooked rice is corrected from small to medium. On the contrary, if the amount B of rice is judged to be medium, and the time B is 3 minutes or less, the amount of rice cooked is corrected from medium to small. If the time B may exceed 4 minutes when the amount of cooked rice is determined to be medium, the amount of cooked rice is corrected from medium to large. On the contrary, if the time B is 4 minutes or less when the amount of cooked rice is judged to be large, the amount of cooked rice is corrected from large to medium.

When the lid temperature sensor 11 detects that the boiling temperature has been reached, the induction heating output is switched from 70% to 90% when the amount of cooked rice is large, and 65 when it is medium.
% To 80%, and when the amount is small, leave it as it is. At this time, the heater drive circuit 24 is controlled to repeat the control in which the body heater 9 and the lid heater 12 are turned on for 1 minute and turned off for 2 minutes.

Wait for 3 minutes to elapse in this state,
Over the course of minutes, the induction heating power is reduced by 30%.
In this state, if the amount of cooked rice is large, the temperature detected by the pan temperature sensor 8 is 120 ° C or higher, 118 ° C or higher for medium amount, and 11 ° C for small amount.
When the temperature rises to 6 ° C or higher, this cooked rice is finished and the course shifts to Murashi.

The unevenness is controlled based on the flow chart shown in FIG. First, the induction heating output is 40 seconds for large amounts of rice,
The medium amount is turned off for 50 seconds, and the small amount is turned off for 60 seconds. During this time, when the temperature of the lower surface of the lid detected by the lid temperature sensor 11 is 106 ° C. or more, the heater driving circuit 24 turns on the lid heater 12 and the body heater 9, and when the temperature of the lower surface of the lid is less than 106 ° C., the heater driving circuit. The lid heater 12 and the body heater 9 are turned off by 24.

When the induction heating output OFF time has passed and the temperature detected by the pan temperature sensor 8 is less than 105 ° C., the induction heating output is 60% for a large amount of rice and 55 for a medium amount.
%, 50% for small amount. This is done for a large amount of rice for 10 seconds, a medium amount for 8 seconds, and a small amount for 5 seconds. Further, when the temperature detected by the pan temperature sensor 8 becomes 107 ° C. or higher while the induction heating output is turned on, the induction heating output is turned off, and heating control is switched by the lid heater 12 and the body heater 9.

When such control is continued for 15 minutes, the unevenness is terminated and the heat retention is started. The heat retention is controlled based on the flow chart shown in FIG. That is, when the temperature detected by the pan temperature sensor 8 is 70 ° C. or higher, the induction heating output is kept off,
The temperature detected by the pan temperature sensor 8 is checked every second. When the temperature detected by the pan temperature sensor 8 becomes lower than 70 ° C., the induction heating output is turned on at 60% for 1 second, and then the induction heating output is turned off for 12 seconds. Further, when the temperature detected by the pan temperature sensor 8 is lower than 70 ° C. and the temperature detected by the lid temperature sensor 11 is 71 ° C. or higher, the lid heater 12 and the body heater 9
Is turned off, and if the temperature detected by the lid temperature sensor 11 is less than 71 ° C., the lid heater 12 and the body heater 9 are turned on.

In the embodiment apparatus having such a configuration,
For example, when a large amount of rice and water are put in the rice cooking pot 5 to start the timer rice cooking, the rice cooking operation is started a predetermined time before the time when the rice is cooked set by the timer.

The rice cooking operation starts with hot water cooking.
In hot-pot cooking, the induction heating output is 80% and the power is turned on for 3 minutes and then turned off for 6 minutes. Then, the amount of cooked rice is determined from the difference A in temperature drop during 6 minutes of rest. If this judgment is correct, a large amount is judged.

Subsequently, the induction heating power is turned on at 80% for 4 minutes, and then for 7 minutes. In this way, the hot water cooking for 20 minutes is completed, and the main rice cooking is started. In this way, the amount of cooked rice is determined within about 60 ° C. at which the rice is gelatinized and prepared for the next main cooked rice.

In this cooked rice, the induction heating output is turned on at 100%. And the pan temperature sensor 8 detects 80 ℃ or higher,
When the lid temperature sensor 11 detects 85 ° C. or higher, the induction heating output is turned off once.

Then, after a 2-minute off period, the induction heating power is now turned on at 70%. In this state, boiling is detected when the temperature detected by the lid temperature sensor 11 rises below 2 ° C. for 2 minutes.

In this process, the time taken for the temperature detected by the lid temperature sensor 11 to reach 90 ° C. to the boiling temperature is checked,
If the time is less than 4 minutes, adjust the amount of cooked rice from a large amount to a medium amount. If the amount of cooked rice is large and correct, the induction heating output is changed to 90%. Further, control of turning on the lid heater 12 and the body heater 9 for 1 minute and 2 minutes is started. Then, this state is continued for 3 minutes, and then the induction heating output is changed to 60%.

In this state, the temperature detected by the pan temperature sensor 8 is 1
Check that the temperature rises to 20 ° C or higher, and if it rises to 120 ° C or higher, complete the main-cooking and shift to the Murashi process. The Murashi process is performed for 15 minutes. The induction heating output is 4
It is turned off for 0 seconds, and if the temperature detected by the lid temperature sensor 11 is less than 106 ° C, the lid heater 12 and the body heater 9 are turned on, and if the detected temperature is 106 ° C or more, the lid heater 12 is turned on.
Also, the body heater 9 is turned off.

After 40 seconds have passed, the lid temperature sensor 11
When the temperature detected by the sensor is less than 105 ° C, the induction heating output is set to 6
Turn on at 0% for 10 seconds. If the temperature detected by the lid temperature sensor 11 may exceed 107 ° C. during this period, the induction heating output is turned off.

When such control is performed for 15 minutes, the unevenness is finished and the temperature is kept. In this way, good rice can be cooked according to the amount of rice cooked. In heat insulation, the temperature detected by the pan temperature sensor is 7
When the temperature is lower than 0 ° C, the induction heating output is turned on at 60%, and when it is 70 ° C or higher, the induction heating output is turned off. When the temperature detected by the lid temperature sensor 11 is 71 ° C. or higher, the lid heater 12 and the body heater 9 are turned off, and when the detected temperature is less than 71 ° C., the lid heater 12 and the body heater 9 are turned on.

FIG. 7 is a graph showing the relationship between the induction heating output, the on / off timings of the body heater 9 and the lid heater 12, the temperature detected by the pan temperature sensor 8 and the temperature detected by the lid temperature sensor 11 in the above rice cooking operation. As shown. In addition, the solid line graph a in the drawing shows the transition of the detected temperature of the pan temperature sensor 8, and the dotted line graph b shows the transition of the detected temperature of the lid temperature sensor 11.

By the way, in the determination of the amount of cooked rice in the hot-pot cooking, for example, when foreign matter is caught, the temperature detection accuracy of the pan temperature sensor 8 is lowered, and when the large amount of cooked rice is erroneously determined to be a medium amount, the heating amount after that. Is a heating amount based on a medium amount until boiling is detected.

That is, the heating for 4 minutes after determining the amount of cooked rice in the hot-pot cooking is performed with the induction heating output of 70%, and the first induction heating output of the main cooking is 90%. In addition, the pot temperature sensor 8 detects 80 ° C. or higher, and the lid temperature sensor 1
The induction heating output off time after detection of 1 above 85 ° C is 2.5 minutes, and after this off period,
The induction heating output is 65%.

However, in this cooked rice, the pan temperature sensor 8 detects 80 ° C. or higher, and the lid temperature sensor 11 detects 85 ° C.
Since the induction heating output is turned off by detecting a temperature equal to or higher than 0 ° C., and boiling is detected when the temperature rise of the temperature detected by the lid temperature sensor 11 for 2 minutes becomes 2 ° C. or less after this off period, Even if the amount of cooked rice is mistakenly determined to be medium, rice is cooked reliably even if it takes some time before boiling.

At the time of boiling detection, the time B until the temperature detected by the lid temperature sensor 11 reaches 90 ° C. to the boiling detection temperature is checked. If the amount of cooked rice is large, this time B should exceed 4 minutes. Therefore, the amount of cooked rice will be corrected from a medium amount to a large amount.

Therefore, the subsequent heating control is performed based on the corrected large amount, and the heating control after boiling is appropriately performed based on the accurate cooked rice amount. Therefore, even if the first rice cooking amount determination is erroneous, the heating control after boiling is appropriately performed, so that good rice cooking can be performed.

Further, since the body heater 9 is turned on to heat the side surface of the inner frame 4 when the induction heating output is off in the case of Murashi, the temperature decrease of the rice cooking pot 5 is prevented when the induction heating output is off. it can. At the same time, the lid heater 12 is turned on to heat the lower surface plate 10 of the lid body 2, so that heat radiation from the lid body 2 can be prevented, and the temperature decrease of the rice cooking pot 5 when the induction heating output is off can be further prevented. Therefore, the rice cooking pot 5 can be kept in a high temperature state during the Murashi period, and delicious gelatinized rice can be cooked.

[0050]

As described above in detail, according to the present invention, the amount of cooked rice is judged by the temperature change of the rice cooker until the temperature at which the rice gelatinizes. The amount of cooked rice is corrected according to the rate of temperature rise on the lower surface of the lid that accompanies the generation of steam at the beginning of boiling, and after that, the heating amount is controlled based on the corrected amount of cooked rice. It is possible to provide a heating method of a rice cooker that can always set properly and cook good rice.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a control circuit configuration of the embodiment.

FIG. 3 is a flowchart showing hot water cooking control by the control circuit of the embodiment.

FIG. 4 is a flowchart showing main rice cooking control by the control circuit of the embodiment.

FIG. 5 is a flow chart showing uneven control by the control circuit of the embodiment.

FIG. 6 is a flowchart showing heat retention control by the control circuit of the embodiment.

FIG. 7 is a graph showing a rice cooking operation in the example.

[Explanation of symbols]

 1 ... Rice cooker main body 2 ... Lid body 5 ... Rice cooker pot 6 ... Induction heating coil 8 ... Pot temperature sensor 11 ... Lid temperature sensor 15 ... Induction heating device 21 ... Control circuit

Claims (1)

[Claims] 1. When cooking rice with a rice cooker having an open top, a rice cooker and heating means for heating the rice cooker, and a lid provided on the upper part of the rice cooker so that the lid can be opened and closed, After the start of rice cooking, the amount of rice cooked is determined by the temperature change of the rice cooker until the temperature at which the rice gelatinizes is reached, and the amount of heating of the heating means thereafter is set based on this determination result. The amount of cooked rice is heated to boiling with the amount of heating, and the amount of cooked rice determined according to the temperature rise rate of the lower surface of the lid due to the generation of steam in the early stage of boiling is corrected, and the amount of cooked rice is heated after boiling with the amount of cooked rice that has been corrected A method for heating a rice cooker, comprising: