JP3221985B2 - Electromagnetic induction heating 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 for cooking rice using electromagnetic induction heating.

[0002]

2. Description of the Related Art In a rice cooker of this type, an electromagnetic induction heating coil is arranged outside a bottom portion of an inner frame of a rice cooker main body accommodating a rice cooker, and a rice cooker having a magnetic metal layer is heated by electromagnetic induction heating. Cooking rice. That is, when a resistance load of the rice cooker is present in the magnetic field of the electromagnetic induction heating coil, a load current is generated and the cooker generates heat.

In such an electromagnetic induction heating system, if no resistance load exists in the magnetic field, that is, if the rice cooker is not set in the rice cooker main body, no load is generated and no load current is generated. From this, conventionally, when starting the rice cooking, the presence or absence of a load current is detected when the electromagnetic induction heating coil is energized, and when the load current cannot be detected, it is determined that the rice cooker is not set. The rice cooking operation is stopped.

[0004]

However, in the method for detecting the presence or absence of a rice cooker after starting rice cooking, the presence or absence of the rice cooker is detected after the electromagnetic induction heating device is operated for rice cooking. Therefore, when the rice cooker is not set, the electromagnetic induction heating device is operated for a while in a no-load state, which has a problem that circuit components of the electromagnetic induction heating device are adversely affected.

Accordingly, the present invention can minimize the operation of the electromagnetic induction heating device in a no-load state as short as possible, and reliably perform control to stop the operation of the electromagnetic induction heating device by detecting the absence of a pan. To provide an electromagnetic induction heating type rice cooker.

[0006]

The present invention SUMMARY OF] is the electromagnetic induction heating means for heating operation the cooking pot with the cooking pot detachably provided rice cooker body provided, rice by heating operation of the cooking pot, unevenness Shino in sequentially performed cooker each stroke, and a timer cooking setting means for starting a time by setting the timer operation Takiagari until the end of the steaming, predetermined time Takiagari time set by the cooking setting hand <br/> stage Start cooking rice before, finish the steaming at the set cooking time, and save
A timer炊Meshite stage of performing temperature, and pan detection means for detecting the presence or absence of cooking pot by temporarily heating operation the cooking pot by heating means in the prior cooking start time by this timer炊Meshite stage, this Means for stopping the timer operation by the timer rice setting means when the pot detecting means detects the absence of the rice cooking pot.

[0007]

In the present invention having such a configuration, when the rice cooking timer is set, the rice cooker is temporarily heated by the electromagnetic induction heating means before the rice cook start time to detect the presence of the rice cooker. When detecting that the rice cooker has not been set, the timer operation is stopped. As a result, the rice cooking operation in the no-load state is not started.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an electromagnetic induction heating rice cooker. Reference numeral 1 denotes a rice cooker main body having an open upper part, and reference numeral 2 denotes a lid provided on the upper part of the main body 1 so as to be freely opened and closed.

The rice cooker main body 1 has an outer frame 3 exposed to the outside and an inner frame 4 provided inside the outer frame 3 with a desired space therebetween. And a rice cooker 5 in the inner frame 4
Is to be accommodated.

The inner frame 4 is made of heat-resistant PPS or glass-filled nylon (6PA) or the like, has a cylindrical shape with a bottom, and has a tape-shaped flat portion provided on the outer peripheral portion of the inner bottom.
The cooking pot 5 can be stably accommodated.

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

Although not shown, a ferrite rod made of iron oxide as a main material and sintered of a material having a high magnetic permeability is attached to the outer surface of the coil base 7 with an adhesive. To prevent release.

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 formed of a ferritic stainless steel layer. The inner surface is coated mainly with PFA resin. To ensure non-stickiness.

A pot temperature sensor 8 is attached to the side surface of the inner frame 4 so that the heat-sensitive portion contacts the outer surface of the rice cooker 5. Also, the pot temperature sensor 8 is provided on the side of the inner frame 4.
A cord-shaped body heater 9 having a comparatively small heat generation capacity is bonded and fixed above. The outside of the body heater 9 is surrounded by a heat insulating plate 10 attached to the outer surface of the inner frame 4.

An induction heating device 11 is mounted inside the bottom of the space surrounded by the outer frame 2 and the inner frame 3 of the rice cooker main body 1, and a control circuit board 12 is mounted inside the side. The lid 2 is composed of an outer frame 13 and a lower plate 14 which comes into contact with the space inside the pot. A lid temperature sensor 15 for detecting the temperature of the lower surface of the lid is attached to the back side of the lower plate 14. A cord-shaped lid heater 16 is bonded and fixed to the back side of the lower surface plate 14. The heat insulating material 1 is provided between the outer frame 13 and the lower plate 14.
7 is arranged apart from the lid heater 16.

The lower plate 14 is made of an aluminum material containing a large amount of Fe component having good heat conductivity, and is made of a material which develops a milky white color by alumite treatment. That is,
About 20 μm to 25 μm alumite treatment
The surface treatment is performed so that a milky white color is generated by the interference of light from the alumina layer.

The cover 2 is provided with an operation panel 18 exposed to the outside and provided with various operation keys and a display unit.
Further, the lid 2 is provided with a steam port 19 for allowing the steam accumulated inside to escape to the outside.

The steam port 19 is provided with a hole 20 in the center of the bottom and a hole 21 around the bottom, a valve 22 which moves up and down inside the bottom, and a partition 23 protrudingly provided inside the top. A cylindrical case 25 having a hole 24 inside the partition 23 is provided. The side surface extends to the vicinity of the top of the case 25 inside the bottom of the case 25, and a hole 26 is provided at the center of the bottom and a space 27 is provided inside the case.
A cylindrical partition 28 having a bottom is formed. Two spaces are formed between the side surface of the case 25 and the side surface of the partition 28, and passages 29 and 30 are formed in the respective spaces. The case 2 on the side where the passage 29 is formed
A hole 31 is provided at the lowermost position on the side surface of
A hole 32 is provided at a position higher than the hole 31 on the side surface of the case 25 on which 0 is formed.

FIG. 2 is a block diagram showing a circuit section, and 41 is a control circuit composed of a microprocessor or the like. The control circuit 41 controls the input of key signals from the induction heating device 11 and the operation panel 18 and also controls the output of display signals and data to the operation panel 18, the input / output circuit 42, and the pan temperature sensor 8. And lid temperature sensor 1
5, a heater drive circuit 43 including a triac (trade name) for controlling ON / OFF of the body heater 9 and the lid heater 16, and a pan detecting means for detecting the presence or absence of a load current when the induction heating device 11 operates. Current detection circuit 44 and buzzer drive circuit 4 for driving and controlling buzzer 45
6, a memory 47 and a time counting circuit 48 for counting the date and time are connected respectively.

The induction heating device 11 comprises a high-frequency current generation circuit 49 and an output adjustment section 50 for adjusting the amount of high-frequency current from the high-frequency current generation circuit 49 and supplying the high-frequency current to the induction heating coil 6. That is, the output adjustment unit 50 adjusts the amount of high-frequency current supplied to the induction heating coil 6 within a range of, for example, 50 to 100%, and turns on and off the output.

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, an eddy current is generated mainly in the ferritic stainless steel layer of the rice cooker 5 facing the heating coil 6, and rice is cooked by Joule heat due to the eddy current. This is performed when the pan 5 generates heat.

As shown in FIG. 3, the operation panel 18 includes, as operation keys, a timer rice cook key 18a, a rice cook key 18b, an off key 18c, a clock adjustment key 18d, and an hour key 18e used to set a time for clock adjustment. , A minute key 18f used for minute setting.

The operation panel 18 has a timer lamp 18g for displaying that the timer is operating, a rice cooker lamp 18h for displaying the process of cooking, a warming lamp 18i for displaying the process of keeping warm, the current time and the cooking time. Is displayed.

The control circuit 41 includes the timer rice cooker key 1
8a, clock key 18d, hour key 18e and minute key 1
When the timer cook time is set by the operation 8f (timer rice setting means) and the timer operation is started, the timer rice control shown in FIG. 4 is performed. (Timer炊Meshite stage) First, to calculate the remaining time until Takiagari time is the difference between the Takiagari time and the current time is set. Then, it is checked whether the remaining time is within 55 minutes, and if it is within 55 minutes, the rice cooking operation is started immediately. This is because it is anticipated that approximately 55 minutes will be required to complete the operations of hot-cooking, main-cooking, and steaming rice.

If the remaining time exceeds 55 minutes, the timer operation is continued, and the remaining time is calculated, for example, every minute.
Then, when the remaining time is 60 minutes, the induction heating output is turned ON for only 1 second and the pot detection is performed. This is the load current detection circuit 4
4 detects the presence / absence of the pan depending on whether or not the load current is detected.

When the presence of the pot is detected, the timer operation is continued, and when the remaining time is 55 minutes, the rice cooking operation is started. When the absence of the pan is detected, the buzzer drive circuit 46 is controlled to drive the buzzer 45 for a fixed time, and then the timer setting is canceled and the rice cooker is turned off. That is, the off key 18c
Is in the same state as was operated.

When the rice-cooking operation is started, each operation of hot-cooking, main rice-cooking, spotting, and heat retention is sequentially performed. In each of these operations, the presence or absence of a pan is detected when the induction heating output is ON, and if the absence of the pan is detected, the buzzer drive circuit 46 is controlled to drive the buzzer 45 for a predetermined time,
Thereafter, the rice cooking operation is stopped and the rice cooker is turned off.

FIG. 5 shows the first rice cooker in the rice cooking operation.
Perform based on. First, the induction heating device 11 is controlled to be turned on for 3 minutes at an induction heating output of 80%. Subsequently, the induction heating output is turned off for 6 minutes.

Then, the amount of rice cooked is determined from the temperature drop detected by the pot temperature sensor 8 for 6 minutes when the induction heating output is turned off, that is, the temperature difference A. That is, A ≧ 10K
If so, the amount of cooked rice is determined to be large, if 10K> A ≧ 3K, it is determined to be medium, and if A <3K, it is determined to be small.

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 is cooked, and turned on at an output of 60% when the amount is small.

After the end of the 20-minute hot-cooking, the rice cooking is subsequently performed. This rice cooking is performed based on FIG. First, if the amount of cooked rice is large, it is turned on at an induction heating output of 100%, if it is medium, it is turned on at an induction heating output of 90%, and if it is small, it is turned on at an induction heating output of 70%. In this state, it is checked whether the temperature detected by the pan temperature sensor 8 is 80 ° C. or higher and the temperature detected by the lid temperature sensor 15 is 85 ° C. or higher.

When the temperature condition satisfies this condition, the induction heating output is turned off for 2 minutes for a large amount of rice, 2.5 minutes for a medium amount, and 3 minutes for a small amount. Thereafter, the induction heating output is turned on again. At this time, if the amount of cooked rice is large, 70%,
It is turned on at 65% for medium amount and 60% for small amount.

In this state, it is checked whether the rise in the temperature detected by the lid temperature sensor 15 becomes 2 ° C. or less / 2 minutes. Then, when this condition is reached, it is detected that boiling has occurred. At this time, the time B until the temperature detected by the lid temperature sensor 15 reaches 90 ° C. to the boiling temperature is checked.

Then, based on the result of the time B, the amount of cooked rice determined at the time of undercooking is corrected. For example, if the time B exceeds 3 minutes in a state where the rice cooking amount is determined to be small, the rice cooking amount is corrected from a small amount to a medium amount. Conversely, if the time B is 3 minutes or less in a state where the rice cooking amount is determined to be a medium amount, the rice cooking amount is corrected from the medium amount to a small amount. In the state where the rice cooking amount is determined to be medium,
If it exceeds 4 minutes, the amount of cooked rice is corrected from a medium amount to a large amount. On the other hand, time B is 4 when it is determined that the amount of cooked rice is large.
If it is less than a minute, the amount of cooked rice is corrected from large to medium.

When the lid temperature sensor 15 detects that the boiling temperature has been reached, the induction heating output is switched from 70% to 90% when the rice cooking amount is large, and 65% when the rice cooking amount is medium.
% To 80%, and if the amount is small, leave it as it is. Further, at this time, the heater driving circuit 43 is controlled to repeat the control of turning the body heater 9 and the lid heater 16 on for one minute and off for two minutes.

Wait for three minutes to elapse in this state.
After the minutes have elapsed, the induction heating power is reduced by 30%.
In this state, if the amount of cooked rice is large, the temperature detected by the pot temperature sensor 8 is 120 ° C. or more, 118 ° C. or more for medium amount, and 11 ° for small amount.
When the temperature reaches 6 ° C. or more, the main rice cooking is finished and the process shifts to spots.

The mura is performed based on FIG. First, the induction heating output is 40 seconds for a large amount of rice, 50 seconds for a medium amount,
For a small amount, it is turned off for 60 seconds. If the temperature of the lower surface of the lid detected by the lid temperature sensor 15 is 106 ° C. or more during this time, the lid heater 16 and the body heater 9 are turned on by the heater driving circuit 43, and if the temperature of the lower surface of the lid is lower than 106 ° C. 43 turns off the lid heater 16 and the body heater 9.

When the temperature detected by the pot temperature sensor 8 becomes less than 105 ° C. after the off time of the induction heating output has elapsed, the induction heating output is reduced to 60% for a large amount of cooked rice and 55% for a medium amount of cooked rice.
%, 50% for small quantities. This is performed for 10 seconds for a large amount of rice, 8 seconds for a medium amount, and 5 seconds for a small amount. If the temperature detected by the pot temperature sensor 8 becomes 107 ° C. or higher while the induction heating output is on, the induction heating output is turned off, and the heating control by the lid heater 16 and the body heater 9 is switched.

If such control is continued for 15 minutes, the murashizu is terminated and the operation shifts to the heat retention. The heat retention is performed based on FIG. First, when the temperature detected by the pot temperature sensor 8 is 70 ° C. or higher, the induction heating output is kept turned off, and the pot temperature sensor 8 is turned off every 12 seconds.
Check the detected temperature. When the temperature detected by the pot temperature sensor 8 is lower than 70 ° C., the induction heating output is turned on at 60% for only 1 second, and then the induction heating output is turned off for 12 seconds. When the temperature detected by the pot temperature sensor 8 is lower than 70 ° C., if the temperature detected by the lid temperature sensor 15 is 71 ° C. or higher, the lid heater 16 and the body heater 9 are turned off, and the temperature detected by the lid temperature sensor 15 is 71 ° C. If it is less, the lid heater 16 and the body heater 9 are turned on.

The induction heating output during the above rice cooking operation,
ON / OFF timing of the body heater 9 and the lid heater 16,
FIG. 9 is a graph showing the relationship between the detected temperature a of the pot temperature sensor 8 and the detected temperature b of the lid temperature sensor 15.

In the embodiment having such a configuration, the timer rice cooker key 18a, the clock setting key 18d, the hour key 18e
When the cooking time is set by operating the minute key 18f and the timer operation is started, the induction heating output is turned on for one second 60 minutes before the cooking time to detect the presence or absence of the pan.

If no pan is detected at this time, the buzzer 4
At 5, the timer operation is stopped and the rice cooker is turned off. When the presence of the pan is detected, the timer operation is continued.

At this time, the presence / absence of the pot is determined by setting the induction heating output to 1
Since it is only turned on for a second, the temperature in the rice cooker 5 hardly rises, and there is no possibility that the subsequent rice cooker will be adversely affected. Also, at this time, even if the rice cooker 5 is not set, the induction heating device 11 operates in a no-load state for 1 second, so that there is almost no possibility of adversely affecting circuit components.

Moreover, since the presence / absence of the pot is detected 5 minutes before the start of the rice cooking, the rice cooking operation is started immediately even if the temperature in the rice cooking pot 5 rises slightly, so that there is no problem. Even before the rice cooker 5 minutes before the start of rice cooking, even if the rice cooker 5 is removed from the rice cooker main body 1, the rice cooker 5 can be set to the rice cooker main body 1 immediately before the rice cooker 5 at least 5 minutes before the rice cooker starts. Will be continued.

When the remaining time until the cooking is completed reaches 55 minutes after the presence of the pot is detected, the rice cooking operation is started. The rice cooking operation starts with the first cooking. In hot-cooking, the induction heating output is turned on at 80% for 3 minutes and then turned off for 6 minutes. Then, the amount of cooked rice is determined from the temperature drop A during the 6-minute pause.

For example, if it is determined that the amount is large, the induction heating output is turned on for 4 minutes at 80%, and then turned off for 7 minutes. In this way, the cooked rice for 20 minutes is finished, and the rice cooking is started.

In the present rice cooking, the induction heating output is turned on at 100%. And the pan temperature sensor 8 detects 80 ° C or higher,
When the lid temperature sensor 15 detects 85 ° C. or higher, the induction heating output is temporarily turned off.

After a two minute off period, the induction heating output is now turned on at 70%. In this state, when the temperature rise for 2 minutes of the temperature detected by the lid temperature sensor 15 becomes 2 ° C. or less, boiling is detected. In this process, the lid temperature sensor 15
Until the detected temperature of the sample reaches 90 ° C to the detected boiling temperature B
Is checked, and if the time B is 4 minutes or less, the amount of cooked rice is corrected from a large amount to a medium amount.

Now, if the amount of cooked rice is large and correct,
Change induction heating power to 90%. Also, the lid heater 16
Then, control for turning on the body heater 9 for 1 minute and turning off for 2 minutes is started. Then, this state is continued for 3 minutes, and thereafter, the induction heating output is changed to 60%.

When steam starts to be generated by boiling, steam enters the space 27 of the steam port 19 through the holes 21 to 26 and from the holes 31 and 32 through the passages 19 and 30. Then, the steam entering the space 27 is discharged to the outside through the holes 24. As the boiling proceeds, the pressure in the pot increases, the amount of steam generated increases, and wrinkles occur to raise the liquid level.

When the pressure rises, the valve 22 is moved from the holes 20 and 21 to the valve 22.
And the valve 22 is pushed up. The valve 22 now closes the hole 26. From the holes 31 and 32, in addition to the steam, liquid such as water that is pushed up by the steam pressure is pushed up through the entrance passages 29 and 30. The vapor and the liquid are separated by the uppermost portions of the passages 29 and 30 and the partition 23, the liquid falls and accumulates in the space 27, and the vapor is discharged to the outside through the hole 24.

Since the hole 26 is closed by the valve 22,
Vapor does not enter through the hole 26. Therefore, space 2
The liquid accumulated in the space 7 is heated by the steam and boiled, so that the pressure in the space 27 is increased and the accumulated liquid does not flow out to the outside.

Further, when a large amount of water is added together with rice, a phenomenon may occur in which water enters through the hole 31 provided on the lower side of the side wall, closes the passage 29, and pressure is not released, and only water increases. is there. In such a case, the hole 32 at a slightly higher position
Then, the steam enters from the hole 24 to the outside through the passage 30 to release the steam pressure.

Further, when the water in the pot runs out, the amount of generated steam decreases, the inside of the pot becomes a negative pressure, and the valve 22 is lowered. Thereby, the hole 26 is opened and the liquid stored in the space 27 is collected in the pot.

By such a series of actions, even when the lid is not provided with the inner lid, it is possible to prevent the boiling water from flowing out from the steam port 19 to the outside. Thereafter, it is checked that the temperature detected by the pot temperature sensor 8 becomes 120 ° C. or higher.

The mulching is performed for 15 minutes. In this spot, the induction heating output is turned off for 40 seconds.
When the detected temperature is lower than 106 ° C., the lid heater 16 and the body heater 9 are turned on, and when the detected temperature is 106 ° C. or higher, the lid heater 16 and the body heater 9 are turned off.

After 40 seconds have passed, the lid temperature sensor 15
If the detected temperature of becomes less than 105 ° C, the induction heating output
Turn on at 0% for 10 seconds. If the temperature detected by the lid temperature sensor 15 becomes 107 ° C. or more during this time, the induction heating output is turned off.

When such control is performed for 15 minutes, the spotting is terminated and the operation is shifted to heat retention. In the heat retention, the induction heating output is reduced by 60% when the temperature detected by the pan temperature sensor 8 falls below 70 ° C.
At 70 ° C. or higher to turn off the induction heating output. If the temperature detected by the lid temperature sensor 15 is 71 ° C. or higher, the lid heater 16 and the body heater 9 are turned off, and the detected temperature becomes 7 ° C.
When the temperature is lower than 1 ° C., control for turning on the lid heater 16 and the body heater 9 is performed.

In the above embodiment, the presence / absence of the rice cooker is detected only once five minutes before the start of rice cooking. However, the present invention is not limited to this. It may be performed several times, such as one minute before, two minutes before, one minute before.

[0060]

As described above in detail, according to the present invention, the operation of the electromagnetic induction heating apparatus in a no-load state can be suppressed as short as possible. An object of the present invention is to provide an electromagnetic induction heating type rice cooker capable of reliably performing control for stopping operation.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram showing a configuration of an operation panel of the embodiment.

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

FIG. 5 is a flowchart showing a single-cooking control by the control circuit of the embodiment.

FIG. 6 is a flowchart showing main rice cooking control by the control circuit of the embodiment.

FIG. 7 is a flowchart showing the unevenness control by the control circuit of the embodiment.

FIG. 8 is a flowchart showing heat retention control by the control circuit of the embodiment.

FIG. 9 is a graph showing a rice cooking operation in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rice cooker main body 2 ... Lid 5 ... Rice cooker 6 ... Induction heating coil 11 ... Induction heating device 18a ... Timer rice cooking key 21 ... Control circuit

Claims (1)

(57) [Claims] 1. A provided an electromagnetic induction heating means for heating operating the cooking pot provided with detachably the cooking pot rice cooker body, rice by heating operation of the cooking pot, the unevenness Shino
In a rice cooker that sequentially performs a process , a timer rice cooking setting means for setting a cooking time until the end of the steaming and starting a timer operation, and starting rice cooking a predetermined time before the cooking time set by the rice cooking setting means. , timer炊that to end the steaming to Takiagari time set perform the coercive temperature
And Meshite stage, the pan detection means for detecting the presence or absence of cooking pot by temporarily heating operation the cooking pot by said heating means in the prior cooking start time by this timer炊Meshite stage, the pan detection means Means for stopping a timer operation by the timer rice cooking setting means when the absence of a rice cooker is detected.