JP3228606B2 - 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 and keeping warm 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.

The rice cooking operation includes processes such as main rice cooking, steaming, and heat retention. The steaming process is performed after so-called dry-up, in which the temperature in the pot rises to a sharp source due to almost no water in the pot. In this spotting process, it is only necessary to keep the temperature of the rice cooker approximately at the boiling temperature, so there is no need for so much heat generation.
Therefore, control is performed to turn on and off the electromagnetic induction heating coil at desired intervals.

[0004] In such a rice cooker, it is necessary that the total power consumption of the heating coil and the power consumption of other circuit components be within the rated power consumption. It is necessary to be able to perform the rice cooking operation and the warming operation.

For this reason, an output mode for continuously operating the electromagnetic induction heating coil in the maximum output state is provided, and the manufacturer can select this output mode to adjust the maximum output. That is, the high-frequency current value supplied to the heating coil in the state where this output mode is selected is adjusted, and the maximum output of the heating coil is adjusted.

[0006]

However, the output of the electromagnetic induction heating coil can be switched in several stages through the rice cooking operation and the heat keeping operation. Thus, the output of the heating coil is switched in a plurality of stages. However, the adjustment of the maximum output alone was not sufficient to sufficiently exhibit the output performance at each stage. Accordingly, the present invention provides an electromagnetic induction heating type rice cooker capable of performing both the maximum output adjustment and the minimum output adjustment of the electromagnetic induction heating output and easily adjusting each output thereof.

[0007]

SUMMARY OF THE INVENTION The present invention comprises an electromagnetic induction heating means and an output control means for variably controlling the heating output of the heating means. The heating means causes a rice cooker housed in the rice cooker body to generate heat. In the induction heating type rice cooker that cooks rice and keeps warm, the heating output of the electromagnetic induction heating means is kept at the maximum value state and the maximum output mode is performed continuously, and the heating output of the electromagnetic induction heating means is kept at the minimum value state And a power adjusting means for adjusting the heating output value of the electromagnetic induction heating means in the maximum output mode and the minimum output mode.

[0008]

According to the present invention having such a structure, the maximum output mode is selected by the selection means, and the heating output of the electromagnetic induction heating means is maintained at the maximum value state, and the operation is continuously performed. In this state, the heating output value of the electromagnetic induction heating means is adjusted. Next, the minimum output mode is selected by the selection means, and the heating output of the electromagnetic induction heating means is maintained at the minimum value state and the operation is continuously performed. In this state, the heating output value of the electromagnetic induction heating means is adjusted.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the configuration of a main part of an electromagnetic induction heating type rice cooker.

The rice cooker main 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 is made of heat-resistant PPS, glass-filled nylon (6PA), or the like, has a bottomed cylindrical shape, and can accommodate the rice cooker 5 therein.

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 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.
The body heater 9 is adhesively fixed at a position above the body heater 9.

The lid 2 is a lower plate 1 which comes into contact with the space inside the pan.
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 plate 10. A lid heater 12 is bonded and fixed to the back side of the lower plate 10.

The lower plate 10 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 lid 2 is provided with an operation panel 13 which is exposed to the outside and has various operation keys and a display unit to be described later. Further, the lid 2 is provided with a steam port 14 for letting steam accumulated inside escape to the outside.

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

FIG. 3 is a block diagram showing a circuit section, and 21 is a control circuit composed of a microprocessor or the like. An input circuit 23 that controls input of signals from the induction heating device 15 and various operation switches 22 to the control circuit 21;
A heater drive circuit 24 including a triac (trade name) for controlling ON / OFF of the pot temperature sensor 8 and the lid temperature sensor 11, the body heater 9 and the lid heater 12, and a display drive circuit 26 for controlling the display unit 25. , A memory 27 and a clock circuit 28 for counting the date and time.

The induction heating device 15 comprises a high-frequency current generation circuit 29 and an output adjustment unit 30 for adjusting the amount of high-frequency current from the high-frequency current generation circuit 29 and supplying the high-frequency current to the induction heating coil 6. That is, the output adjusting unit 30 includes a variable resistor, adjusts the amount of high-frequency current supplied to the induction heating coil 6 in 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. 2, the operation panel 13 includes, as various operation keys 22, a clock key 22a for designating a time setting mode, an hour key 22b used for time setting in the time setting mode, and a time key 22b in the time setting mode. A minute key 22c used for weighing, and a menu key 22 used to select a rice cooking menu to be "soft,""normal,""warm," or "porridge."
d, a rice cooking key 22e for starting a rice cooking operation, a heating key 22f for starting a warming operation, an off key 22g for stopping rice cooking, warming, and a timer operation, and a timer key 22h for starting a timer operation.

The display unit 25 of the operation panel 13 is provided with a timer lamp 31a for displaying that the timer is operating, a rice cooker lamp 31b for displaying that rice is being cooked, and a heat-retention lamp 31c for displaying that heat is being kept. In addition, a liquid crystal display 32 is provided which displays the current time, the cooked time at the time of timer rice cooking, and further displays a rice cooking menu of "soft", "normal", "kake" and "porridge".

The control circuit 21 performs the rice cooking control in four steps, namely, the rice cooking, the main rice cooking, the steaming, and the warming. The first rice cooking is performed based on FIG. .

That is, the induction heating device 15 is controlled and first turned on at an induction heating output of 80% for 3 minutes. Subsequently, the induction heating output is turned off for 6 minutes. Then, the amount of cooked rice 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, if A ≧ 10K, the amount of cooked rice is determined to be large, and 10K>
If A ≧ 3K, it is determined that the amount is medium, and if A <3K, it is determined that it is 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 20-minute cooking process is completed, the rice cooking is subsequently performed. As shown in FIG. 5, this rice cooker is turned on at an induction heating output of 100% for a large amount of cooked rice, turned on at an induction heating output of 90% for a medium amount, and turned on at an induction heating output of 70% for a small amount. 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 11 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 cooked rice, 2.5 minutes for a medium amount of cooked rice, and 3 minutes for a small amount of cooked rice. 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 11 becomes 2 ° C. or less / 2 minutes. Then, when this condition is reached, it is detected that boiling has occurred. At this time, a time B until the temperature detected by the lid temperature sensor 11 reaches 90 ° C. to the boiling temperature is checked.

Then, based on the result of the time B, the rice cooked amount determined at the time of the rice cooker 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 reaching the boiling temperature is detected by the lid temperature sensor 11, the induction heating output is switched from 70% to 90% when the amount of cooked rice is large, and 65% when the amount of cooked rice is medium.
% To 80%, and if the amount is small, leave it as it is. At this time, the heater drive circuit 24 is controlled to repeat the control of turning on and off the body heater 9 and the lid heater 12 for one minute and two minutes.

Wait for 3 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.

As shown in FIG. 6, first, the induction heating output is turned off for 40 seconds for a large amount of rice, 50 seconds for a medium amount, and 60 seconds for a small amount. If the temperature of the lower surface of the lid detected by the lid temperature sensor 11 is 106 ° C. or higher during this time, the lid heater 12 and the body heater 9 are turned on by the heater driving circuit 24, and if the temperature of the lower surface of the lid is lower than 106 ° C. 24 turns off the lid heater 12 and the body heater 9.

If 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.
%, 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. When 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 is switched by the lid heater 12 and the body heater 9.

When such control is continued for 15 minutes, the spotting is terminated and the operation is shifted to heat retention. As shown in FIG. 7, when the temperature detected by the pan temperature sensor 8 is 70 ° C. or higher, the induction heating output is kept off, and the temperature detected by the pan temperature sensor 8 is checked every 12 seconds. 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 11 is 71 ° C. or higher, the lid heater 12 and the body heater 9 are turned off.
If the detected temperature is less than 71 ° C., the lid heater 12 and the body heater 9 are turned on.

The on / off timing of the induction heating output and the body heater
And the ON / OFF timing of the lid heater 12, the detected temperature a of the pot temperature sensor 8, and the detected temperature b of the lid temperature sensor 11.
FIG. 8 is a graph showing the relationship of.

The control circuit 21 performs control for adjusting the maximum value and the minimum value of the induction heating output shown in FIG. That is, when the device is in the off state,
When the menu key 22d is turned on, the setting menu is changed. At this time, the menu key 22d is continuously turned on for 2 seconds or more, and the clock key 22a is turned on in this state.
When operated, the maximum output mode of the induction heating device 15 is selected. (Selecting means) In the maximum output mode, the display unit 2 of the operation panel 13
As shown in FIG. 11 (a), No. 5 turns on the rice cooker lamp 31b and the warming lamp 31c at the same time, and simultaneously displays all items which are not normally displayed on the liquid crystal display 32.

As another display example, as shown in FIG. 11B, the character "H" is displayed on the current time display section of the liquid crystal display 32.
I "may be displayed, and the pot temperature during operation" 100 ° C. "may be displayed on the cooked time display section.

In the maximum output mode, the induction heating output is set to the maximum output state to continuously operate. At this time, there is no ON operation of the clock key 22a and the menu key 22
When d is continuously turned on for 10 seconds or more, the operation display state is set. At this time, the display unit 25 displays (d) in FIG.
As shown in the figure, a symbol such as "A0" indicating a process such as cooking, boiling detection and cooking is displayed on the current time display portion of the liquid crystal display 32, and the temperature "1" is displayed on the cooking time display portion.
20.degree. C. "is displayed, and the menu selection state is displayed. .

In this state, O of the menu key 22d is
When the N operation is canceled, the state returns to the initial off state. Also, during the maximum output mode, the off key 22g is turned on, the pot temperature becomes 120 ° C. or higher, 60 minutes have passed since the start of operation, no pan was detected, and there was a power failure for 2 seconds or more. Returns to the initial off state.

During the maximum output mode, the watch key 22a
Is turned on again, the minimum output mode is selected.
(Selecting means) When the ON operation of the clock key 22a is released,
It returns to the maximum output mode again.

Also in the minimum output mode, the display unit 25 of the operation panel 13 simultaneously turns on the rice cooker lamp 31b and the warming lamp 31c as shown in FIG. Display all items that are not displayed at the same time.

As another display example, as shown in FIG. 11C, the character "L" is displayed on the current time display section of the liquid crystal display 32.
O "may be displayed, and the temperature of the operating pot" 50 ° C. "may be displayed on the cooking time display section to distinguish it from the display in the maximum output mode.

In the minimum output mode, for example, when the output is switched to 1200 W, 1150 W, 1100 W,
In the case of eight stages of 50 W, 1000 W, 950 W, 900 W, and 850 W, a minimum of 800 W is continuously output.

When the pan temperature sensor 8 fails during the maximum output mode, the processing shown in FIG. 10 is performed. That is, when a state in which the pan temperature sensor 8 continuously detects a temperature lower than −2 ° C. for 5 minutes or more occurs, it is determined that the pan temperature sensor 8 is disconnected, and the maximum output mode is released.
This process is performed in the same manner even during the minimum output mode.

In the embodiment apparatus having such a configuration,
For example, water is put into the cooking pot 5, and the menu key 22d is set to 2
The clock key 22a is turned on for more than a second, and the clock key 22a is turned on in this state. As a result, the maximum output mode is selected, and the heating output of the induction heating device 15 is in a state of continuous maximum output.

In this maximum output mode, the induction heating output is adjusted to the output adjusting section 30 so as to fall within the tolerance of the rated power consumption.
Adjust by adjusting the variable resistor. When the adjustment of the induction heating output in the maximum output mode is completed, the clock key 22
a is turned ON. Thereby, the minimum output mode is selected.

In the minimum output mode, the induction heating output is adjusted by operating another variable resistor of the output adjusting section 30 so as to be 50% as designed, for example, if the design is 50% of the maximum output value. .

When the ON operation of the clock key 22a is stopped, the mode returns to the maximum output mode.
When is operated, the maximum output mode is canceled and the first off state is set.

As described above, the adjustment of the induction heating output in the maximum output mode and the adjustment of the induction heating output in the minimum output mode can be performed by simple key operations. The state of the maximum output mode and the state of the minimum output mode can be easily confirmed on the display unit 25.

Further, the switching from the maximum output mode to the minimum output mode and the switching from the minimum output mode to the maximum output mode are performed depending on whether or not the clock key 22a is turned on, so that the mode can be easily switched. .

In the maximum output mode, the temperature detected by the pan temperature sensor 8 reaches 120.degree. C., 60 minutes have elapsed since the start of the operation, and a power failure of 2 seconds or more has been performed without operating the off key 22g. When this occurs, the maximum output mode is released and the first off state is set. This prevents the pot from running out of water when operating in maximum output mode,
When an operation such as forgetting the operation of the 2g or an abnormality such as the power plug being unplugged occurs during the operation, it can be returned to the initial off state, so that safety can be ensured.

If the pot temperature sensor 8 is disconnected, the detected temperature shows an abnormally low value of less than -2 ° C. If this state continues for 5 minutes or more, the disconnection of the pot temperature sensor is judged and the maximum value is determined. Since the output mode can be released and returned to the initial off state, safety can be ensured also in this case.

The adjustment of the maximum value and the minimum value of the induction heating output is generally performed by the manufacturer, and the rice cooker after the adjustment is shipped and used by the user. Therefore, if the adjustment of the maximum value and the minimum value of the induction heating output is simply performed on the user side, inconvenience occurs. Since no selection is made, and the menu key 22d and the clock key 22a are provided at separate positions, there is no danger that the maximum output mode will be selected even if the user operates the keys incorrectly.

When rice cooking is performed on the user side, the following operation is performed. That is, in a standard rice cooking course, when, for example, a large amount of rice and water are put into the rice cooking pot 5 and timer rice cooking is started, the rice cooking operation is started a predetermined time before the timer set cooking time.

[0056] The rice cooking operation starts with a single-sided 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 difference A during the 6-minute pause. In this case, a large amount is determined.

Subsequently, it is turned on for 4 minutes at an induction heating output of 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 this one-side cooking, the amount of rice to cook is determined within about 60 ° C. at which the rice gelatinizes, and the rice is prepared for the next main rice cooking.

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 11 detects 85 ° C. or higher, the induction heating output is temporarily turned off.

After a two minute off period, the induction heating output is turned on, this time at 70%. In this state, when the temperature rise of the cover temperature sensor 11 for 2 minutes becomes 2 ° C. or less, boiling is detected. In this process, the time until the temperature detected by the lid temperature sensor 11 reaches 90 ° C. to the boiling detection temperature is checked. If the time 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 12
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%.

In this state, the temperature detected by the pot temperature sensor 8 is 1
Check that the temperature is 20 ° C. or higher. The mulching is performed for 15 minutes. In this spot, the induction heating output is turned off for 40 seconds. During this time, the lid heater 12 and the body heater 9 are turned on when the temperature detected by the lid temperature sensor 11 becomes lower than 106 ° C., and when the detected temperature becomes 106 ° C. or higher, the lid heater 12 is turned off. And the body heater 9 is turned off.

After 40 seconds have passed, the lid temperature sensor 11
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 11 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 turned on at 60% when the temperature detected by the pot temperature sensor is lower than 70 ° C., and is turned off when the temperature is 70 ° C. or higher. When the temperature detected by the lid temperature sensor 11 is 71 ° C. or more, the lid heater 12 and the body heater 9 are turned off, and the detected temperature becomes 71 ° C.
If the temperature is lower than 0 ° C., control to turn on the lid heater 12 and the body heater 9 is performed.

By performing such a rice-cooking operation, the body heater 9 is turned on to heat the side surface of the inner frame 4 when the induction heating output is off at the time of spotting. , The temperature of the rice cooker 5 can be prevented from lowering. At the same time, the lid heater 12 is also turned on to heat the lower plate 10 of the lid 2, so that heat radiation from the lid 2 can be prevented,
It is possible to further prevent the temperature of the rice cooker 5 from decreasing when the induction heating output is turned off.

[0065]

As described above in detail, according to the present invention, there is provided an electromagnetic induction heating type rice cooker capable of adjusting both the maximum output and the minimum output of the electromagnetic induction heating output and easily adjusting each output. It can be provided.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of an operation panel of the embodiment.

FIG. 3 is a block diagram showing a control circuit configuration of the embodiment.

FIG. 4 is a flowchart showing control of hot-spot cooking by the control circuit of the embodiment.

FIG. 5 is a flowchart showing control of the main rice cooking by the control circuit of the embodiment.

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

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

FIG. 8 is a graph showing a rice cooking operation in the embodiment.

FIG. 9 is a flowchart showing adjustment control of the maximum value and the minimum value of the induction heating output by the control circuit of the embodiment.

FIG. 10 is a flowchart showing a disconnection determination process of the pot temperature sensor when the maximum value of the induction heating output is adjusted by the control circuit of the embodiment.

FIG. 11 is a view showing various display examples during induction heating output adjustment in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rice cooker main body 2 ... Lid 5 ... Rice cooker 6 ... Induction heating coil 15 ... Induction heating device 21 ... Control circuit 22a ... Clock key 22d ... Menu key 29 ... High frequency current generation circuit 30 ... Output adjustment part

Claims (1)

(57) [Claims] 1. An electromagnetic induction heating means and an output control means for variably controlling a heating output of the heating means, wherein the heating means causes a rice cooker housed in a rice cooker body to generate heat to cook and heat rice. In the induction heating type rice cooker, the maximum output mode in which the heating output of the electromagnetic induction heating means is continuously maintained at a maximum value state and the heating output of the electromagnetic induction heating means is continuously maintained at a minimum value state An electromagnetic induction heating rice cooker comprising: a selection unit for selecting a minimum output mode to be performed; and an output adjustment unit for adjusting a heating output value of the electromagnetic induction heating unit in a maximum output mode and a minimum output mode.