JP2586289Y2 - 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, and more particularly to a rice cooker capable of keeping an inner pot warm.

[0002]

2. Description of the Related Art Conventionally, in a rice cooker, an inner pot is housed in an outer container of a rice cooker body, and the inner pot is indirectly heated by a heater provided on the bottom surface of the outer container, or recently, heated by a heating coil. Direct heating (in this case, the inner pot needs to be formed of a magnetic material such as stainless steel) is performed by electromagnetic induction to cook rice. When the rice cooking is completed, the power supply to the heating heater or the heating coil is stopped, and the power is supplied to the heat retaining heater provided on the outer peripheral portion of the outer container to heat the outer container, thereby keeping the inner pot warm. Like that. Further, the inner lid of the lid closing the inner pan energizes a primary coil provided on a shoulder portion of the rice cooker body, and induces an induced electromotive current to a secondary coil provided on the lid by electromagnetic induction. The generated dew is radiated by a lid heating heater to be heated, thereby removing attached dew.

[0003]

However, since the rice cooker requires a heater to keep the inner pot warm,
Since the number of parts increases and the number of manufacturing steps for mounting the parts increases, the cost increases. In addition, since the heating state of the inner lid is determined by the amount of electricity to the primary coil, the inner lid may be in an excessively heated state, possibly causing yellowing of the rice or melting of the lid resin part. There is. In view of the above problems, the present invention can be manufactured at low cost without a heat retaining heater.
Moreover, an object of the present invention is to provide a rice cooker in which the inner lid is not overheated.

[0004]

According to the present invention, in order to achieve the above object, an inner pot is accommodated in an outer container of a rice cooker main body, and a primary coil is disposed on a shoulder portion of the outer container. Rice cooker in which a high-frequency current is passed from an oscillator to a secondary coil to generate an induced electromotive current in a secondary coil provided in the lid and an inner lid provided in the lid is heated by lid heating means. In the vessel, while the outer container or the inner pot is made of a magnetic material, the primary coil is disposed near the upper outer periphery of the inner pot, thereby heating the inner lid with the primary coil, The outer container or the inner pot is induction-heated to indirectly or directly heat the inner pot. Also,
Temperature detection means may be provided near the switching transistor of the oscillator, and the output from the oscillator may be suppressed if the temperature detected by the temperature detection means exceeds a predetermined temperature.

[0005]

According to the above arrangement, when a high-frequency current is applied to the primary coil by the oscillator, an induced electromotive current is generated in the secondary coil. As a result, the inner lid is heated by the lid heating means, and the dew adhered to the inner lid is removed, while the outer pan or the inner pan is induction-heated, and the inner pan is kept warm. Also,
If a temperature detecting means is provided in the vicinity of the switching transistor of the oscillator, there is a fixed relationship between the detected temperature and the heating temperature of the inner lid. The heating of the inner lid is stopped by stopping the energization of the primary coil.

[0006]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a rice cooker, which generally includes a rice cooker main body 1, an inner pot 2, and a lid 3. Rice cooker body 1
Comprises a rectangular exterior body 4 and an outer container 5 housed in the exterior body 4. A primary coil 7 is disposed on the shoulder 6 of the exterior body 4 in the vicinity of the upper outer periphery of the inner pot 2. The outer container 5 is made of a magnetic material such as stainless steel. On the bottom outer surface, a heater (not shown), an oscillator 8 for the primary coil 7, and a control circuit 9 for controlling the oscillator 8 are provided.
And a temperature sensor 10 such as a thermistor.

As shown in FIG. 3, the oscillator 8 includes a rectifier circuit 12 connected to an AC power supply composed of four diodes 11 connected in a bridge, and a resonance capacitor 13 connected to the rectifier circuit 12. A switching transistor 14 connected in series with the capacitor 13;
A drive pulse oscillation circuit 15 that outputs a transistor drive pulse to the base of the switching transistor 14
Consists of The temperature sensor 10 is arranged near the switching transistor 14, and the detected temperature is input to the control circuit 9. The primary side coil 7 is connected in parallel to the capacitor 13 of the oscillator 8,
A C resonance circuit is formed.

[0008] The inner pot 2 is made of metal and is accommodated in the outer container 5 of the rice cooker main body 1. The lid 3 includes an outer lid 16.
A lid ring 18 integrated with the outer lid 16 by a welding ring 17, a radiator plate 19 made of stainless steel fixed to the center of the lid ring 18, and a projection 20 formed at the center of the radiator plate 19. And an inner lid 21 detachably attached to the rice cooker main body 1. The inner lid 21 is rotatably provided on the shoulder 6 of the rice cooker main body 1 around a hinge (not shown).

The outer peripheral portion of the space formed by the outer lid 16 and the lid ring 18 of the lid 3 (slightly inside the welding ring 17).
Accommodates a secondary coil 22 so as to face the primary coil 7, and a lid heating coil 24 connected to the secondary coil 22 via an impedance conversion circuit 23 in the center. Is housed. A packing 25 is sandwiched between the lid ring 18 and the outer peripheral portion of the heat radiating plate 19 so that the inside of the inner pan 2 can be closed in a sealed state.

In the rice cooker having the above configuration, after the rice is cooked by the heater (not shown), the primary coil 7 is turned on.
This keeps the heat and removes the inner lid 21. That is, after the rice cooking is completed, a drive signal is issued from the control circuit 9 to the drive pulse oscillation circuit 15 of the oscillator 8. This allows
The drive pulse oscillating circuit 15 outputs a drive pulse to the base of the transistor 14 to turn on the transistor 14, and after energizing the primary coil 7 for a predetermined time, turns off the transistor 14.

As a result, a high-frequency current flows through the primary coil 7 to generate an alternating magnetic field. The outer container 5 located in this magnetic field is induction-heated, and an induced electromotive current flows through the secondary coil 22. The induced electromotive current generated in the secondary coil 22 is transferred to the lid heating coil 24 through the impedance conversion circuit 23.
A high-frequency current is passed through to generate an alternating magnetic field. As a result, the heat radiating plate 19 is induction-heated, the temperature of the inner lid 21 rises, and the dew attached to the inner lid 21 is removed. in this way,
Since the primary coil 7 can be used not only for exposing the inner lid 21 but also for keeping the inner pot 2 warm, a heat keeping heater which has conventionally been disposed on the upper outer peripheral portion of the outer vessel for keeping the heat is unnecessary. It is possible to reduce the score and reduce the cost.

Meanwhile, the temperature near the transistor 14 is detected by the temperature sensor 10 during the temperature keeping and the dew dropping. Since the detected temperature has a fixed relationship with the heating temperature of the inner lid 21, if a temperature (abnormal temperature T ₁ ) corresponding to a state where the inner lid 21 is abnormally heated is detected,
The control circuit 9 issues a control signal to the drive pulse oscillation circuit 15 of the oscillator 8 to keep the transistor 14 in the off state. As a result, the high-frequency current flowing through the primary coil 7 is stopped, and the induction heating of the heat sink by the lid heating coil 24 is suppressed. As a result, the temperature of the inner lid 21 decreases.

When the detected temperature drops below the temperature T ₂ (see FIG. 5) in which the abnormal temperature T ₁ has hysteresis, the control circuit 9 drives the drive pulse oscillation circuit 15 of the oscillator 8. A signal is issued, and a high-frequency current is supplied to the primary coil 7 in the same manner as described above, so that heat is kept and the dew is removed.

In the above embodiment, the outer coil 5 is heated by the primary coil 7 to keep the temperature during the heat keeping. However, the inner pot 2 is made of a magnetic material, so that the inner pot 2 is directly heated.
May be heated to keep it warm. In the above embodiment, the primary coil 7 is energized or de-energized depending on whether the temperature detected by the temperature sensor 10 exceeds the abnormal temperature. May be controlled. Furthermore, in the above-described embodiment, the heat radiation plate 19 is induction-heated by the lid heating coil 24 to prevent the dew from adhering to the inner lid 21. However, as shown in FIG. The heat radiation plate 19 may be directly heated at 26. in this case,
The impedance conversion circuit 23 is unnecessary, and the heat sink 19 does not need to be formed of stainless steel.

[0015]

As is apparent from the above description, according to the rice cooker according to the present invention, the outer pot or the inner pot is made of a magnetic material, and the inner pot is kept warm by induction heating with the primary coil. Since it is made possible, a heat retaining heater is not required unlike the related art, making it easy to manufacture and reducing the cost.

Further, the temperature detecting means is provided in the vicinity of the switching transistor of the oscillator to control the amount of current supplied to the primary coil in accordance with the detected temperature, so that the inner lid can be appropriately heated. In addition, yellowing of rice and melting of the lid resin portion do not occur.

[Brief description of the drawings]

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

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a partial electric circuit diagram of FIG. 1;

FIG. 4 is a partially enlarged cross-sectional view showing another embodiment.

FIG. 5 is a hysteresis characteristic diagram at an abnormal temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rice cooker main body, 2 ... Inner pan, 3 ... Lid, 5 ... Outer container, 6
... shoulder, 7 ... primary side coil, 8 ... oscillator, 21 ... inner lid,
22 ... secondary side coil, 24 ... lid heating coil (lid heating means).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-68634 (JP, A) JP-A-6-105740 (JP, A) JP-A-6-62956 (JP, A) JP-A-56- 148327 (JP, A) JP-A-57-40896 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) A47J 27/00

Claims (2)

(57) [Scope of request for utility model registration] 1. A rice cooker body containing an inner pot in an outer container, a primary coil disposed on a shoulder of the outer container, and a high-frequency current supplied from an oscillator to the primary coil.
In a rice cooker in which an induced electromotive current is generated in a secondary coil provided in a lid and an inner lid provided in the lid is heated by lid heating means, the outer container or the inner pot is made of a magnetic material. On the other hand, by arranging the primary side coil near the upper outer peripheral portion of the inner pan, the primary side coil heats the inner lid and indirectly or directly heats the outer container or the inner pan by induction heating. A rice cooker characterized by keeping the inner pot warm. 2. The apparatus according to claim 1, wherein a temperature detecting means is provided near a switching transistor of the oscillator, and the output from the oscillator is suppressed when a temperature detected by the temperature detecting means exceeds a predetermined temperature. Item 2. The rice cooker according to Item 1.