JPH07155251A - Electromagnetic rice cooker - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an appropriate rice-cooking control system for an IH rice cooker by detecting foreign matter when cooking foreign matter. [Structure] In the IH type rice cooker, the temperature rise after the boiling process when foreign matter is placed on the center sensor for detecting the inner pot temperature is considerably lower than the temperature rise during normal rice cook. Become. Therefore, the foreign matter cooking state is determined on the basis of the difference in the degree of temperature rise after the boiling process, and when it is determined that the foreign matter cooking state is determined, the "muramura step" transition temperature during normal rice cooking is determined. Instead, the process was shifted to the "Murashi process" or "Heat retention process" to prevent abnormalities in the inner pot (rice cooker) or heating for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic rice cooker configured to generate heat by heating an inner pot itself by electromagnetic induction by a work coil, and more particularly to an electromagnetic rice cooker having a foreign rice cooking prevention function. It is about.

[0002]

2. Description of the Related Art In recent years, an electromagnetic rice cooker employing an electromagnetic induction heating device as a heating means for heating an inner pot has been developed and provided. In the case of the electromagnetic rice cooker, the Joule heat generated by the eddy current generated in the inner pot by the electromagnetic induction by the work coil is used for heating the rice.

[0003]

By the way, in the above-mentioned electromagnetic rice cooker, when the rice is cooked, the temperature of the inner pan is detected by a temperature sensor such as a center sensor which comes into contact with the bottom surface of the inner pan. It is customary to cook rice by controlling the amount of heating and the heating state by the heating means (work coil) for each rice cooking process such as water absorption, cooking, and purging based on the level of increase in the detected temperature. Detecting the temperature of the inner pot is extremely important for properly executing the above rice cooking control and cooking delicious rice.

However, in the case of the conventional general electromagnetic rice cooker described above, if foreign matter such as rice grains intervenes between the inner pot and the sensor surface of the temperature detecting sensor (for example, the center sensor),
The effect of heat transfer from the inner pot to the sensor surface is reduced, and there is a very large difference between the temperature detected by the temperature detection sensor and the actual heat generation temperature of the inner pot. There is a risk of malfunction of the rice cooker (melting resin), rice cooking for a long time, and burning.

It is extremely convenient for the user if such a foreign rice cooked state can be detected in an appropriate rice cooking process, and it is possible to prevent the rice cooker from malfunctioning or burning due to the above-mentioned resin melting. It is an important issue that needs to be solved in an electromagnetic rice cooker.

[0006]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above problems and providing an appropriate rice cooking control system by detecting foreign matter when cooking foreign matter.
A work coil that heats the inner pot by electromagnetic induction and an inner pot temperature detection sensor surface that detects the temperature of the inner pot by contacting the sensor surface with the bottom surface of the inner pot are provided. In an electromagnetic rice cooker that sequentially executes each rice cooking process such as water absorption, cooking, and purging according to the rising process of the pan temperature, the cooking process detected by the inner pan temperature detection sensor Foreign matter detecting means for detecting the presence of foreign matter on the sensor surface of the inner pot temperature detecting sensor based on the difference in the degree of change in the detected temperature after the boiling process of the inner pot temperature detecting sensor by the foreign matter detecting means. When it is detected that foreign matter is present on the sensor surface of the cooking pot, even if the temperature of the inner pot detected by the inner pot temperature detection sensor does not reach the original transition temperature to the uneven process, And it is configured with a cooking process changing means for shifting the process steaming the process or heat retaining process is provided.

[0007]

In the so-called IH type electromagnetic rice cooker, the degree of temperature rise after the boiling process when a foreign substance is placed on the sensor surface of the inner pot temperature detecting sensor for detecting the inner pot temperature is not the same as the temperature during normal rice cooking. It is considerably lower than the degree of increase. Therefore,
In the configuration of the present invention, the foreign matter cooking state is determined on the basis of the difference in the temperature rise degree after the boiling process, and when it is determined that the foreign matter cooking state is, the determination of the spotty process transition temperature during normal rice cooking is performed. Without doing so, shift to the Murashi step or the heat retention step to prevent abnormalities in the inner pot or heating for a long time.

[0008]

As described above, according to the electromagnetic rice cooker of the present invention, in the foreign substance cooked state in which a foreign substance is present between the sensor surface of the inner pot temperature detecting sensor and the bottom face of the inner pot, the accurate inner pot temperature cannot be detected. It is possible to prevent an abnormal rise in the inner pot temperature and realize proper rice cooking control at low cost. In addition, as a result, the conventional melting of resin, burning, and unnecessary cooking for a long time can be eliminated.

[0009]

【Example】

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

1 to 4 show an electromagnetic rice cooker according to a first embodiment of the present invention.

The electromagnetic rice cooker of this embodiment is used for both rice cooking and heat retention, and has a bottomed cylindrical outer case constructed so that an inner pot (rice cooker) 3 can be set inside. 1 and a lid unit 2 that covers the upper part of the outer case 1.

The outer case 1 is composed of a bottomed cylindrical cover member 4 made of synthetic resin, and a synthetic resin shoulder member 5 connected to the upper end of the cover member 4, and the inside thereof. Is provided with a bottomed cylindrical inner case 6 for removably setting the inner pot 3.

An upper end of the inner case 6 is engaged with the shoulder member 5 and a heat insulating heater 26 is provided at the upper and lower central portions of the outer peripheral surface.
And a cylindrical upper inner case 6a formed of a thin metal plate
And a saucer-shaped lower inner case 6b made of synthetic resin that engages with the lower end of the upper inner case 6a. The bottom center of the lower inner case 6b is located at the center of the bottom of the inner pot 3. A center sensor 7 is provided for making contact with each other.

The center sensor 7 functions as a temperature detecting sensor for detecting the temperature of the inner pot 3, and as shown in FIG. 3, the thermistor 8 serving as a temperature detecting portion and the inner pot 3 are set. An inner pot set detection sensor 9 for detecting whether or not there is built-in.

The center sensor 7 of the present embodiment is a sensor which is arranged in a circular storage portion 10 formed in the central portion of the lower inner case 6b so as to be vertically movable and has the thermistor 8 built therein. It comprises a holder 11 and a spring 12 for urging the sensor holder 11 upward (that is, in the direction of coming into contact with the bottom surface of the inner pot 3). In the case of the present embodiment, the upper surface of the sensor holder 11 is a circular flat surface, and the sensor cap 13 that abuts on the bottom surface of the inner pot 3 is provided.

Further, the inner pan set detection sensor 9 is
The reed switch 14 and the magnet 1 which are provided at opposite positions on the outer circumference of the sensor holder 11.
5 and the reed switch 14 when the sensor holder 11 is moved downward (in other words, when the inner pot is set).
And a shielding plate 16 inserted between the magnet 15 and the magnet 15.

An annular work coil 17 is formed on the lower surface of the lower inner case 6b so as to surround the center sensor 7.
Is provided. The work coil 17 functions as a magnetic force generating means in the electromagnetic induction heating device.
Reference numeral 18 denotes a ferrite core that shields the magnetic force generated by the work coil 17 so as not to affect the equipment existing below.

The lid unit 2 has an outer cover 19 made of synthetic resin forming an outer peripheral surface, an inner cover 20 made of synthetic resin forming an outer peripheral annular portion on the inner peripheral surface, and the inner cover 2
It is formed in a hollow structure by the heat dissipation plate 21 which covers the opening at 0. The lid unit 2 is rotatably attached to one side of the shoulder member 5 via a hinge mechanism 22, and the lid unit 2 is provided on the open end side thereof.
There is provided a lock mechanism 23 that engages with a predetermined position to maintain the closed state of the lid unit 2. Further, reference numeral 24 is a steam outlet, and 25 is a lid heater.

Between the inner case 6 and the outer case 1 is housed a microcomputer unit 27 for controlling energization of the work coil 17, the lid heater 25 and the heat retaining heater 26. Also, the shoulder member 5
An operation panel 28 forming an operation unit is provided on the side opposite to the hinge mechanism. On this operation panel 28,
Various switches necessary for rice cooking, and a display unit for displaying a rice cooking menu selected by each of these switches, a switch level, etc., and making it visible to the user are provided. Reference numeral 29 is a fan motor that serves as a drive source of a cooling fan (not shown) for cooling a power transistor (not shown) for activating the work coil 17.

Next, the electrical construction of the electromagnetic rice cooker of this embodiment will be described with reference to the electric circuit diagram shown in FIG. The parts corresponding to the parts shown in FIG. 2 are designated by the same reference numerals.

The electric power from the commercial AC power source 30 is supplied to the lid heater 25 and the heat retaining heater 26 through a temperature fuse 31 that detects abnormal heating of the inner pot 3 and melts it, and is stepped down by a step-down transformer 32. It is supposed to be rectified by the rectifier 33 and supplied to the microcomputer unit 27 as its power source. The power from the commercial power source 30 is supplied to the work coil 17 via the diode bridge 34 and the choke coil 36. Also, reference numeral 61,
62 is a smoothing capacitor, 63 is a resonant capacitor, 64
Is a diode.

The work coil 17, the heat retaining heater 26,
The shoulder heaters 25 are connected in parallel with each other.

Triacs 37 and 38 are connected between the heat retaining heater 26 and the commercial AC power source 30 and between the shoulder heater 25 and the commercial AC power source 30, respectively. The gates of these triacs 37 and 38 are turned on by a command from the microcomputer unit 27.
The control signals from the PNP transistors 39 and 40 controlled to be turned on / off are given. Further, the work coil 17 is provided with a control signal from a switching transistor 35 which is ON / OFF controlled by a command from the microcomputer unit 27.

The microcomputer unit 27
Operates on the basis of a clock signal from the reference frequency generation circuit (OSC) 41 and controls the transistors 35, 39, 40 according to a predetermined program, whereby the work coil 17, the shoulder heater 25 and the heat retaining heater 26 are controlled. Control energization. This energization control is performed based on the output signal from the thermistor 8 built in the center sensor 7. Reference numeral 42 is a thermostat, 43 is switches, 44 is a timer setting display, 45 is liquid crystal display means,
Reference numeral 46 is a buzzer that generates a notification sound when the rice cooking is completed, which will be described later.

The microcomputer unit 27 has functional means for controlling the energization of the work coil 17 during rice cooking and the energization of the work coil 17 according to the rice cooking menu.

Next, the details of the foreign rice cooking control in the electromagnetic rice cooker of this embodiment will be described in detail with reference to the time chart shown in FIG. 4 and the flow chart shown in FIG.

That is, first, in step S ₁ of the flowchart of FIG. 5, the work coil 17 is turned on to start cooking rice.

Then, in step S ₂ , it is determined whether or not the temperature Ts detected by the center sensor 7 has reached the water absorption temperature of 50 ° C. or higher shown in FIG. If the result of the determination is YES, the process proceeds to step S ₃ to enter the water absorption process, and the work coil 17 is turned on and off to maintain the water absorption temperature at a value of around 50 ° C. within the predetermined water absorption process execution time t ₁ . Water absorption operation is executed by.

After that, in step S ₄ , it is judged whether or not the water absorption process execution time t ₁ has elapsed, and if it is judged YES, the work coil 17 is continuously turned on again and cooked in step S ₅ with full power. Enter the process.

When the total number is judged in the middle of the cooking process and heating according to the judgment result is continued for a predetermined time, the center sensor 7 detects it after a boiling process (100 ° C.) as shown in FIG. The temperature Ts exceeds 105 ° C.

Therefore, in step S ₆ , it is determined whether the temperature Ts detected by the center sensor 7 is 105 ° C. or higher, and in step S ₇ , the determination result is YE.
For example, it is determined whether the state of S has continued for 20 seconds.

Then, when the temperature reaches 105 ° C. or higher, 2
If 0 seconds have passed, it is further determined whether increased to proceed to the detected temperature Ts is 110 ° C. or more above the center sensor 7 at step S _8.

As a result, if it is determined to be YES, the process proceeds to step S ₉ and the temperature detected by the center sensor 7 is the "muramurai process" transition determination temperature 130 in the normal rice cooking process.
Determine whether or not the temperature exceeds ℃. Then, when the temperature is 130 ° C. or higher, the process proceeds to step S ₁₀ and the predetermined time is passed.
Execute the "purple process" in t ₂ .

[0034] Then, the course of the "steaming process" execution time t ₂ determines the flow proceeds to step S _11, when the YES (steaming completion) "steaming process" execution time t ₂ has elapsed, step In S ₁₂ , the buzzer is notified that rice cooking is completed (cooking up), the "heat retaining step" of step S ₁₃ is entered, and the heat retaining heater 26 is turned on (normal rice cooking control: see solid line characteristics in FIG. 4).

On the other hand, unlike the above, not the detected temperature Ts of the center sensor 7 from 105 ° C. to a temperature determination (110 ° C.?) In the determination is NO the above 20 seconds of the step S ₈ to 110 ° C. increases Temperature, that is, the temperature T detected by the center sensor from the latter half of the boiling process in the cooking process.
When the rising temperature of s is slower than that during normal rice cooking, some foreign matter is present on the lower surface of the inner pot 3 and the inner pot 3
From the center sensor 7 to the sensor surface, it is determined that the heat transfer rate has deteriorated, and the transition temperature (130 ° C. or higher?) Determination in step S ₉ above is not performed.
As it is shifted to "steaming process" in step S ₁₀ to execute the "steaming process" (foreign matter detection steaming step: see the broken line characteristic of FIG. 4).

[0036] Subsequently, the operation executes the processing of steps S ₁₁ to S ₁₃ in the same manner as during the normal cooking process proceeds to "incubating process".

That is, in the configuration of the rice cooking control system of this embodiment, the degree of increase in the temperature Ts detected by the center sensor 7 is monitored from the latter half of the boiling process in which a high temperature state is reached, and the foreign matter is cooked from the characteristic that the degree of increase slows down. The state is accurately detected, and when the foreign substance is cooked, the detected temperature Ts higher than that is detected.
Since it is designed to proceed directly to the “muramura process” without raising the temperature, it is possible to eliminate resin melting and strong charring due to an abnormal rise in the inner pot temperature, and unnecessary long-time rice cooking operations. It becomes possible to realize an appropriate rice cooking function.

(2) Second Embodiment Next, FIG. 6 shows the control characteristics of the foreign matter rice control in the second embodiment of the present invention.

In the foreign matter cooking control of the first embodiment described above, the degree of increase in the temperature Ts detected by the center sensor 7 is monitored from the latter half of the boiling process in the latter half of the cooking process to enter the high temperature state, and the increase in the characteristic becomes slow. It is possible to accurately detect that the foreign matter is being cooked, and when the foreign matter is being cooked, the detection temperature Ts is not further increased, and the "mulling process" is performed as it is, but substantially the same effect is obtained. For example, as shown in FIG. 6, it can also be realized by directly shifting to the “heat-retaining step” without passing through the “unevenness step”.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electromagnetic rice cooker according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view (III-III enlarged cross-sectional view of FIG. 1) of a center sensor unit of the electromagnetic rice cooker according to the same embodiment.

FIG. 3 is a connection diagram showing an electric circuit configuration of the electromagnetic rice cooker according to the embodiment.

FIG. 4 is a characteristic diagram showing rice cooking characteristics corresponding to changes in the center sensor detected temperature during normal rice cooking and foreign material rice cooking in the electromagnetic rice cooker according to the embodiment.

FIG. 5 is a flowchart showing the content of foreign matter detection and rice cooking control of the electromagnetic rice cooker according to the embodiment.

FIG. 6 is a characteristic diagram showing rice cooking characteristics corresponding to changes in temperature detected by a center sensor during normal rice cooking and foreign rice cooking in an electromagnetic rice cooker according to a second embodiment of the present invention.

[Explanation of symbols]

3 is an inner pot, 7 is a center sensor, 17 is a work coil, 2
7 is a microcomputer unit, and 46 is a boiled rice notification buzzer.

Claims (1)

[Claims] 1. A work coil comprising: a work coil that heats an inner pot by electromagnetic induction; and an inner pot temperature detection sensor surface that detects the temperature of the inner pot by bringing the sensor surface into contact with the bottom surface of the inner pot. In the electromagnetic rice cooker that sequentially executes each rice cooking process such as water absorption, cooking, and mudling according to the rising process of the inner pan temperature due to the energization of Foreign matter detection means for detecting the presence of foreign matter on the sensor surface of the inner pot temperature detection sensor based on the difference in the degree of change in the detected temperature after the boiling process of the cooking step, and the foreign matter detection means When it is detected that a foreign substance is present on the sensor surface of the inner pot temperature detection sensor, the inner pot temperature detected by the inner pot temperature detection sensor has not reached the original transition temperature to the Murashi process. An electromagnetic rice cooker, which is provided with at least a rice-cooking process changing unit that shifts the above-mentioned rice-cooking process to a purging process or a heat-retaining process.