JP2586285Y2 - Electric 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 an electric rice cooker.

[0002]

2. Description of the Related Art Conventionally, as an electric rice cooking jar, there is one disclosed in Japanese Utility Model Laid-Open No. 2-142223, for example, in which a lid is detached from a jar body and can be easily washed. In this electric rice cooker, a heater is buried in the opening edge of the jar main body for the purpose of heating a heating plate provided on the lid to prevent the occurrence of dew, and the heater is brought into contact with the heating plate. Let it transmit heat.

However, in this electric rice cooker, since the heating plate is heated from the outer peripheral side, the temperature cannot be made uniform, and the temperature at the center may not be sufficiently increased. Also, to heat the center of the heating plate,
It is necessary to increase the amount of heating by the heater, but this results in an abnormally high temperature of the jar body. Furthermore, it is necessary to ensure the contact state between the heating plate and the opening edge of the jar body so that the heat of the heater is efficiently transmitted to the heating plate, and high assembly accuracy is required.

[0004] In order to solve these problems,
By providing a lid heater on the lid for exposure, and making the lid heater non-contact with the jar body,
For example, one disclosed in Japanese Patent Application Laid-Open No. 4-338414 has been proposed in which the lid is detached from the jar body so as to be easily cleaned. In this electric rice cooker, a mutual induction circuit is formed by a primary circuit provided in the jar main body and a secondary circuit including a lid heater provided in the lid, and an electromotive force generated in the secondary circuit by the mutual induction action. The heating plate which is supplied to the lid heater and closes the inner pan is heated.

[0005]

However, in such an electric rice cooker, there is no means for detecting the temperature of the heating plate. Further, simply providing the temperature detecting means on the lid cannot disconnect the jar from the jar, so that the lid cannot be removed.
Therefore, in the electric rice cooker, the value of the current flowing to the lid heater has to be determined by the winding ratio between the primary coil and the secondary coil of the lid. The amount of power consumed is determined, and the temperature of the heating plate cannot be adjusted accurately. For this reason, in the lid heater, the removal of water droplets attached to the heating plate may be insufficient, or the heating plate may be overheated. Also, it is not possible to control the power at the time of dew dropping and at the time of heat retention. In view of the above problems, the present invention provides an electric rice cooker in which a lid heater is provided in a non-contact manner with respect to a jar main body so that the lid can be attached and detached. An object of the present invention is to provide an electric rice cooker capable of adjusting the temperature of a plate to a desired temperature, reliably removing dew adhering to the heating plate, and controlling the heat retention.

[0006]

According to the present invention, in order to achieve the above object, a jar body is provided with an oscillating circuit and a primary circuit having a primary coil, while a lid is provided with a lid heater and a secondary heater.
By providing a secondary circuit having a secondary coil, a mutual induction circuit is formed, an electromotive current is generated in the secondary circuit by a mutual induction action in the mutual induction circuit, and the heating provided on the lid body by the lid heater. In an electric rice cooker that heats a plate, while providing a temperature sensing means for suppressing the amount of electricity supplied to the lid heater when the heating plate becomes a predetermined temperature or higher, an on / off state of the temperature sensing means is detected. A lid heating adjusting means for adjusting the amount of current supplied to the lid heater is provided in the primary circuit.
Further, a temperature detecting means such as a thermistor for detecting the temperature of the heating plate is provided in the jar body, and a lid heating for adjusting the amount of electricity to the secondary circuit by the mutual induction action based on a detection signal from the temperature detecting means. The adjusting means may be provided in the primary circuit.

[0007]

In the electric rice cooker having the above-described structure, the dew generated on the heating plate is removed by generating an electromotive current in the secondary coil by the mutual induction action and heating the heating plate. When the temperature of the heating plate rises above a predetermined temperature, the temperature sensing means or the temperature detection means stops heating by the lid heater.
The lid heating adjusting means detects the stop of heating by the lid heater in the secondary circuit, and adjusts the amount of heating by the lid heater thereafter.

[0008]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an electric rice cooker according to the present invention, wherein 1 is a jar body, 2 is an inner pot, and 3 is a lid. The jar main body 1 includes a rectangular exterior body 4 and an outer container 5 housed in the exterior body 4. Rice cooker 6 is provided on the outer surface of the bottom of outer container 5.
And a primary coil 7 is provided on the outer periphery of the upper end of the exterior body 4. Since the primary coil 7 is air-core, a ferrite 7a is provided below so that magnetic flux is concentrated (see FIG. 3). A lid opening / closing switch 8 is provided at a corner of the exterior body 4. The lid opening / closing switch 8 is turned on when a magnet 14 provided on the lid 3 described below approaches, and turned off when separated from the magnet 14. It detects opening and closing, but can be replaced by a microswitch. A not-shown heater is provided on the outer surface of the side surface of the outer container 5, and a pot temperature detecting means 9 such as a thermistor is provided at the center of the side surface.

The inner pot 2 is made of metal and is housed in the outer container 5 of the jar body 1. The lid 3 closes the inner pot 2 accommodated in the jar main body 1 and is attached to a shoulder of the jar main body 1 so as to be pivotable about a hinge and detachably. A heating plate 10 is attached to the lid 3 so as to close the inner pan 2, and a secondary coil 11 is provided on the outer periphery of the heating plate 10 so as to face the primary coil 7. . On the back surface of the heating plate 10, a lid heater 12 connected to the secondary coil 11 and a temperature-sensitive switch 13 are provided. This temperature switch 13
The heating plate 10 can sufficiently perform the exposure,
In addition, a thermostat or the like may be used to adjust the temperature so as to be turned off when the temperature reaches a predetermined set temperature that does not cause excessive heating. A magnet 14 is provided at a corner of the lid 3 to face the lid open / close detection switch 8 when the lid 3 is closed.

In the jar body 1 of the electric rice cooker,
As shown in FIG. 2, a high-frequency oscillator 15 for the primary coil is provided inside the bottom of the exterior body 4, and a control circuit 16 that controls the high-frequency oscillator 15 and has a function as a lid heating adjustment unit.
Is provided. The high-frequency oscillator 15 is composed of four bridge-connected diodes. The rectifier circuit 17 is connected to an AC power supply, the resonance capacitor 18 is connected to the rectifier circuit 17, and the switching is connected in series to the capacitor 18. And a driving pulse oscillating circuit 20 that outputs a transistor driving pulse to the base of the switching transistor 19.

The primary coil 7 is connected to the high-frequency oscillator 15
To form an LC resonance circuit 21. The lid open / close detection switch 8 is connected to the control circuit 16. The control circuit 16 controls the amount of power to the rice cooking heater 6 based on a rice cooking start switch (not shown) or a pot temperature detecting means (not shown) at the time of cooking rice, or by detecting the on / off state of the temperature-sensitive switch 13. The drive pulse oscillation circuit 20 is controlled based on a signal from the shuttle temperature detecting means. The control circuit 16 calculates input power based on the input current detected by the input current detection circuit 22. The change in the input power causes the temperature-sensitive switch 13 to calculate the input power.
ON / OFF state can be detected. On the other hand, 2 of lid 3
A lid heater 12 and a temperature-sensitive switch 13 are connected in series to the secondary coil 11, and a secondary circuit is formed.

In the electric rice cooker having the above configuration,
The rice is cooked by the rice cooking heater 6, and in the cooking stage before the rice cooking is completed, the high frequency oscillator 15 is sent from the control circuit 16.
A drive signal is issued to the drive pulse oscillation circuit 20 of FIG. As a result, the driving pulse oscillation circuit 20
A drive pulse is supplied to the base of the transistor to turn on / off the transistor 19, and a high-frequency current is applied to the primary coil 7 to generate an alternating magnetic field.
An electromotive current is caused to flow through 1 by a mutual induction action. When the electromotive current flows through the lid heater 12, the heating plate 10
Is heated and the attached dew is removed (dew dropping).

When the heat retention by the heat retention heater is started after the rice cooking is completed, the control circuit 16 issues a drive signal to the drive pulse oscillation circuit 20 of the high frequency oscillator 15 so that the heating plate 10 is maintained at a constant temperature. Heat.

In the following, the above-mentioned exposure will be described with reference to a graph shown in FIG. 5 in accordance with a flowchart shown in FIG. First, in step S1, the inner pot 2 is heated by the rice cooker 6 to start cooking rice. Then, in Step 2, it is determined whether or not the temperature of the hook has reached 100 ° C. based on the detection signal from the hook temperature detecting means. If the temperature has not reached 100 ° C., the heating of the inner pot 2 is continued. If the temperature has reached 100 ° C., it is determined that the water contained in the inner pot 2 has become a boiling state, and the process proceeds to step S3. (Cooking power) W to W _L1
And maintain boiling. During this time, water evaporates one after another, and the temperature of the kettle continues to rise above 100 ° C. immediately before cooking.

Next, in step S4, it is determined whether the temperature of the inner pot 2 has reached 110.degree. If the temperature has not reached, the heating of the inner pot 2 is continued. If the temperature has reached, the process proceeds to step S5.
As described above, the drive pulse is applied to the base of the transistor 19, and the lid heater 12 is energized by the mutual induction action to start heating the heating plate 10 and remove the dew. . During this time, the heating of the inner pot 2 is continued, and the temperature of the pot further rises.

Then, in step S6, the temperature of the pot is 125 ° C.
To determine if it has been reached. If not, inner pot 2
Is continued, and if it has reached, the process proceeds to step S7 to reduce the rice cooking power W to W _L2 (<W _L1 ), thereby suppressing the heating of the inner pot 2 and performing additional cooking.

Subsequently, in step S8, it is determined whether the temperature of the heating plate 10 has risen to a predetermined temperature (120 ° C.) and the temperature-sensitive switch 13 has been turned off. This is done by detecting the product of the input voltage, that is, the change in input power, because the input current changes in the primary circuit due to a change in load on the secondary circuit when the temperature-sensitive switch 13 is turned off. And
If it is determined that the temperature-sensitive switch 13 has not been turned off, the heating by the lid heater 12 is continued in that state, and the exposure is continued. If it is determined that the heater is turned off, the lid heater 12 is not energized at this time, and the temperature of the heating plate 10 gradually decreases. Perform intermittently for a short time.

At this time, it is determined again in step S10 whether the temperature of the heating plate 10 is equal to or higher than a predetermined temperature, that is, whether the temperature-sensitive switch 13 is turned on. If it is off, the intermittent oscillation of the primary circuit is maintained, and if it is on, the power supply to the lid heater 12 is restarted in step S11. However, since the lid heater 12 does not overheat the heating plate 10 by this energization, the temperature-sensitive switch 13 is not turned off, and the heating plate 10 is heated for a certain period of time, so that dew can be reliably removed.

As described above, the temperature-sensitive switch 13 limits the temperature rise of the heating plate 10 caused by the lid heater 12, and
Since the ON / OFF state of the temperature-sensitive switch 13 can be detected on the primary circuit side, the heating plate 10 can be reliably maintained at a desired temperature irrespective of a change in the ambient atmosphere temperature of the electric rice cooker, and the dew can be reliably exposed. It is possible to remove it.

If the dew-off control is performed after cooking the rice, the inner pot 2 is controlled to keep the temperature in accordance with the flowchart shown in FIG. That is, first, in step S20
Then, the heating of the inner pan 2 is switched to the heater for keeping warm, and the keeping of heat is started. Then, in step S21, it is determined whether or not the pot temperature is 70 ° C. or higher based on the detection signal from the pot temperature detecting means. If the temperature is equal to or higher than 70 ° C., the process proceeds to step S22, and the energization to the heat retaining heater is stopped. Further, the oscillation by the drive pulse oscillation circuit 20 is stopped, and the transistor 1
9 is turned off so that no high-frequency current is generated in the primary coil 7. As a result, no electromotive current is generated in the secondary coil 11, so that the lid heater 12 does not generate heat, and the heating plate 10 is in a non-heated state. On the other hand, if the temperature is equal to or lower than 70 ° C., the process proceeds to step S23 to energize the warming heater, start oscillation by the drive pulse oscillation circuit 20, heat the heating plate 10, and perform warming and dew-off from above. It is. As described above, since the heating plate 10 is maintained at a constant temperature during the warming, the rice is appropriately warmed and the dew adheres.

In the above embodiment, the temperature-sensitive switch 13
Is provided on the secondary circuit side, for example, on the primary circuit side, for example, in the LC resonance circuit 21 (position shown by A in FIG. 2), or in the middle of wiring between the lid open / close detection switch 8 and the control circuit 16 (shown by B in FIG. 2). Position). However, the temperature-sensitive switch 13 needs to be provided at a position that is easily affected by a change in temperature due to the heating plate 10, and be turned off when the heating plate 10 becomes higher than the set temperature. Accordingly, when the LC resonance circuit 21 is provided at the position A,
When the temperature-sensitive switch 13 is turned off, the primary coil 7
Is cut off, and no electromotive current is generated in the secondary circuit, so that the lid heater 12 does not generate heat and the heating plate 10 is not heated. Further, when the primary coil 7 is provided at the position B in the middle of the wiring, the control circuit 16 detects this state and issues a signal to the drive pulse oscillation circuit 20 in the same manner as when the lid is opened. Does not generate a high-frequency current, and the heating plate 10 is not heated as described above.

Further, in the above-described embodiment, the temperature rise of the heating plate 10 is detected by the temperature-sensitive switch 13 provided on the lid 3, but the temperature change of the heating plate 10 is changed on the jar body 1 side instead. For example, the temperature of the heating plate 10 may be detected by bringing a thermistor or the like into pressure contact with the upper side surface (the position indicated by C in FIG. 3) of the inner pan 2 which is easily affected by the above. However, in this case, the detected temperature is input to the control circuit 16 to determine whether or not the heating plate 10 has a value exceeding the set temperature. Need to stop.

Further, in the above embodiment, the primary side coil 7
The secondary coil 11 and the secondary coil 11 are provided so as to face each other along the outer periphery of the upper opening of the inner pot 2, but may be provided so as to face each other at a corner of the exterior body 4.

[0024]

As is clear from the above description, according to the electric rice cooker according to the present invention, by providing the temperature sensing means, the temperature rise at the heating plate can be directly suppressed to a predetermined value or the temperature can be reduced. While the temperature of the heating plate is detected by the detecting means, the temperature of the heating plate is adjusted by providing the lid heating adjusting means, so that the heating plate is always kept at the desired temperature regardless of a change in the ambient atmosphere temperature. By controlling this, it is possible to ensure that the dew is removed, and it is also possible to perform the heat retention control.

[Brief description of the drawings]

FIG. 1 is a perspective view of an electric rice cooker according to the present embodiment.

FIG. 2 is an electric circuit diagram of the electric rice cooker shown in FIG.

FIG. 3 is a partial sectional view of FIG. 1;

FIG. 4 is a flowchart illustrating the control of the exposure.

FIG. 5 is a flowchart showing heat retention control.

FIG. 6 is a graph showing an on / off state of a lid heater and a temperature change of a heating plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Jar body, 3 ... Lid, 7 ... Primary side coil, 10 ...
Heating plate, 11 ... secondary side coil, 12 ... lid heater, 13 ...
Temperature-sensitive switch (temperature-sensitive means), 15 ... high-frequency oscillator, 16
... Control circuit (cover heating adjusting means), 20... Drive pulse oscillation circuit.

Claims (2)

(57) [Scope of request for utility model registration] 1. A mutual induction circuit is formed by providing a primary circuit having an oscillation circuit and a primary coil in a jar main body and providing a secondary circuit having a lid heater and a secondary coil in a lid body. An electric rice cooker in which an electromotive current is generated in a secondary circuit by a mutual induction action in the mutual induction circuit to heat a heating plate provided on the lid with a lid heater, wherein the heating plate is at a predetermined temperature or higher. A temperature sensing means for interrupting energization to the lid heater, and a lid heating adjustment means provided in the primary circuit for detecting the on / off state of the temperature sensing means and adjusting the amount of energization to the lid heater. And an electric rice cooker. 2. A mutual induction circuit is formed by providing a primary circuit having an oscillation circuit and a primary coil in a jar main body, and providing a secondary circuit having a lid heater and a secondary coil in a lid body. An electric rice cooker in which an electromotive current is generated in a secondary circuit by a mutual induction action in the mutual induction circuit to heat a heating plate provided on the lid with a lid heater; A temperature detecting means such as a thermistor for detecting the temperature of the heating plate, and an amount of electricity supplied to the secondary circuit by the mutual induction action provided on the primary circuit, based on a detection signal from the temperature detecting means. An electric rice cooker comprising: