JPH08266401A - Induction heating rice cooker - Google Patents

Abstract

PURPOSE: To provide an induction heating rice cooker wherein a shielding structure of high-frequency magnetic field is more simplified. CONSTITUTION: An induction heating rice cooker wherein a ferrite core 3 provided on the surface of a heating coil 2 and two nearly circular shield rings 4 (4a, 4b) which are provided near the heating coil 2 function as a magnetic shielding means as in conventional rice cookers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating type rice cooker used in general households.

[0002]

2. Description of the Related Art FIG. 5 shows the structure of a conventional induction heating type rice cooker. Reference numeral 1 is a pot made of magnetic metal for containing rice and water, and a heating coil 2 for induction-heating the pot 1 by generating a high-frequency magnetic field is provided on the bottom of the pot 1. A high frequency power source 5 for supplying a high frequency to the heating coil 2 is provided in the main body 6 that houses the pan 1.

With the above structure, the heating coil 2 receives the high frequency power supplied from the high frequency power supply 5, and generates a high frequency magnetic field of about 20 kHz. This high frequency magnetic field interlinks with the pan 1. At this time, since the pot 1 is made of magnetic metal, an induction current is generated in the pot 1 due to the interlinking high-frequency magnetic field, and the pot 1 itself generates heat. Due to this heat generation, the rice and water contained in the pan 1 are heated and rice cooking proceeds. This induction heating type rice cooker has high heating efficiency because it heats the pot 1 itself and can cook rice with a strong heating power, so that the taste of rice is very good.

[0004]

However, the conventional induction heating type rice cooker has a problem in the method of shielding the high frequency magnetic field generated by the heating coil 2. That is, if the high-frequency magnetic field leaks from the main body 6, nearby devices may malfunction. In order to prevent this magnetic leakage, the conventional structure uses the ferrite core 3 and the reflection frame 4. FIG. 6 shows the structure of the ferrite core 3, which is arranged in a cross shape with respect to the heating coil 2. Since the ferrite core 3 has a small magnetic resistance, the generated high frequency magnetic field concentrates and flows in the ferrite core 3. The reflection frame 4 is composed of a strip-shaped aluminum plate that is short-circuited, and the induction current generated by the interlinking of the high-frequency magnetic field is short-circuited to consume magnetic energy. Therefore, by using the ferrite core 3 and the reflection frame 4, the high frequency magnetic field generated by the heating coil 2 does not leak from the main body 6.

At this time, in the conventional structure, since the strip-shaped short-circuited aluminum plate is used as the reflecting frame 4, the material cost,
The cost is high in terms of production man-hours.

The present invention solves the problems of the conventional structure, and it is a first object of the present invention to provide an induction heating type rice cooker having a simpler high-frequency magnetic field shield structure. I am trying. Moreover, it is the 2nd-4th objective to provide the 2nd-4th means which achieve the said 1st objective.

[0007]

A first means of the present invention for achieving the first object is a pot for containing rice and water, and a heating coil for inductively heating the pot by generating a high frequency magnetic field. A magnetic shield means for preventing a high-frequency magnetic field generated by the heating coil from leaking out of the apparatus, wherein the magnetic shield means has a ferrite core and two shields provided in the vicinity of the heating coil and having a substantially circular cross section. It is an induction heating type rice cooker consisting of a ring.

Second aspect of the present invention for achieving the second object
In particular, the shield ring is an induction heating type rice cooker in which the diameter of the second shield ring arranged on the lower side of the device is larger than the diameter of the first shield ring arranged on the upper side of the device. Is.

The third means of the present invention for achieving the third object is, in particular, the induction heating in which the shield ring is only the third shield ring thicker than the diameter of the second shield ring. It is a rice cooker.

Further, the fourth means of the present invention is, in particular, 18 times in phase with the current supplied to the heating coil to the third shield ring.
This is an induction heating type rice cooker that supplies high-frequency currents that differ by 0 °.

[0011]

The first means of the present invention is an induction heating type rice cooker in which a ferrite core and two shield rings provided in the vicinity of the heating coil and having a substantially circular cross section act as magnetic shielding means similar to the conventional one. It is a thing.

The second means of the present invention further increases the shield effect by making the diameter of the second shield ring arranged on the lower side of the device larger than the diameter of the first shield ring arranged on the upper side of the device. It is a high induction heating type rice cooker.

A third means of the present invention is a simple induction heating type rice cooker having a one-layer shield structure in which the shield ring is only the third shield ring.

The fourth means of the present invention supplies a high-frequency current having a phase opposite to that of the current flowing through the heating coil to the third shield ring to cancel the high-frequency magnetic field generated from the heating coil to further enhance the shield effect. It is an enhanced induction heating rice cooker.

[0015]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIG. A heating coil 2 for generating a high-frequency magnetic field and inductively heating the pan 1 is provided at the bottom of the pan 1 for containing rice and water. A high-frequency power source 5 for supplying a high-frequency current to the heating coil 2 is provided at the bottom of the rice cooker body 6 in which the pan 1 is detachably accommodated. Further, ferrite cores 3 are arranged in a cross shape on the surface of the heating coil 2 as shown in FIG. 4 so that the high frequency magnetic field generated by the heating coil 2 is concentrated and flows in the ferrite core 3. . Further, in the vicinity of the heating coil 2 at the bottom of the rice cooker body 6, the first
The shield ring 4a and the second shield ring 4b are arranged. The first shield ring 4a and the second shield ring 4b are composed of conductors having a substantially circular cross section. In this embodiment, copper wires each having a wire diameter of about 3 mm are provided so as to form a closed circuit. The shield ring 4 and the ferrite core 3 constitute a magnetic shield means.

The operation of this embodiment will be described below. The heating coil 2 is driven by the high frequency current supplied from the high frequency power supply 5.
A high-frequency magnetic field is generated in the pan, and the pan 1 is induction-heated to cook rice. At this time, of the high-frequency magnetic field generated from the heating coil 2, the leakage magnetic flux that does not interlink with the pan 1 flows concentratedly in the ferrite core 3 having a low magnetic resistance. Also the main body 6
Since the first shield ring 4a and the second shield ring 4b provided near the bottom of the heating coil 2 and the heating coil 2 are each formed of a closed-circuit copper wire, they are generated by the high-frequency magnetic field interlinked with the copper wire. The high frequency current is short-circuited. Therefore, of the high frequency magnetic field generated from the heating coil 2, the leakage magnetic flux that does not interlink with the pan 1 is demagnetized by the action of the shield ring 4. That is, the ferrite core 3 and the shield ring 4 act as a magnetic shield means, and the high frequency magnetic field generated by the heating coil 2 leaks from the main body 6 to the outside with extremely small leakage flux.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In this embodiment, the wire diameter of the copper wire of the second shield ring 4b described in the first embodiment is about 1.5 times the wire diameter of the first shield ring 4a.

With the above configuration, the first embodiment
The induction heating type rice cooker having a higher shield effect than the shield effect of the above is realized. The reason for this is that the second shield ring 4b is arranged at a lower position than the first shield ring 4a, and the magnetic flux easily leaks.
This is because the wire diameter of b is made larger than the wire diameter of the first shield ring 4a and the current flowing through the second shield ring 4b is increased.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. The shield ring used in this embodiment is only one third shield ring 4c arranged at the position of the second shield ring 4b used in the first or second embodiment. Thus, as the third shield ring 4c, a copper wire having a larger wire diameter than the first shield ring 4a and the second shield ring 4b is short-circuited in a ring shape. In this embodiment, a copper wire having a wire diameter of 6 mm is used as the third shield ring 4c.

In this way, an induction heating type rice cooker having a shield effect comparable to the conventional one is used as a very simple structure in which the third shield ring is also received instead of the conventionally used reflection frame of the aluminum plate. It has been realized.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. In this embodiment, as shown in FIG. 3, the third shield ring 4c is used as a coil,
The phase of the high-frequency current supplied to the heating coil 2 is
The high frequency power supply 5 supplies currents different by 180 °.

The operation of this embodiment will be described below. By using the third shield ring 4c as a coil and supplying a high-frequency current having a phase opposite to that of the current flowing through the heating coil 2 to the high-frequency magnetic field generated by the heating coil 2 from the third shield ring 4c, A magnetic field with a phase difference of 180 ° is generated. The magnetic flux generated by the third shield ring 4c cancels the leakage magnetic flux from the heating coil 2 to realize an induction heating type rice cooker having a higher shield effect.

(Experimental Example) The results of an experiment for confirming the shield effect of the induction heating type rice cooker of each of the above-mentioned Examples will be reported below. In this experiment, the magnetic field strengths at points A and B shown in FIG. 4 are measured in comparison with the conventional one. The experimental results are shown in Table 1.

[0024]

[Table 1] As described above, according to this embodiment, the first shield ring 4a and the second shield 4a formed by short-circuiting the copper wire instead of the conventional reflection frame formed by short-circuiting the aluminum plate in a strip shape are used. The induction heating type rice cooker having the same shielding effect as the conventional one is realized as a very simple structure using the shield ring 4b.

Further, the wire diameter of the second shield ring 4b arranged below the first shield ring 4a is made larger than the wire diameter of the first shield ring 4a, so that the induction heating type having a higher shield effect can be obtained. This is the realization of a rice cooker.

Furthermore, an induction heating type cooked rice having a shield effect equivalent to that of the conventional one is adopted as a very simple structure in which the shield ring is only the third shield ring 4c using a wire diameter larger than that of the second shield ring 4b. It is what realizes the vessel.

Further, the third shield ring 4c is used as a coil and a high frequency current supplied to the heating coil 2 and 180
° Induction heating type rice cooker with even higher shield effect is realized by supplying currents with different phases to generate a magnetic field in the opposite direction to the magnetic field generated from the heating coil 2 to cancel the leakage flux. There is something.

[0028]

The first means of the present invention is a pot for containing rice and water, a heating coil for generating a high frequency magnetic field to induction heat the pot, and a high frequency magnetic field generated by the heating coil leaks out of the apparatus. And a magnetic shield means for preventing the occurrence of the above-mentioned problems. The magnetic shield means has a structure including a ferrite core and two shield rings provided in the vicinity of the heating coil and having a substantially circular cross section. It is possible to realize an induction heating type rice cooker having a shield effect equivalent to that of.

In the second means of the present invention, particularly, in the shield ring, the diameter of the second shield ring arranged on the lower side of the device is made larger than the diameter of the first shield ring arranged on the upper side of the device. As a configuration, it is possible to realize an induction heating type rice cooker having a higher shield effect.

The third means of the present invention, in particular, has a very simple structure and is similar to the conventional one in that the shield ring is composed only of the third shield ring which is thicker than the diameter of the second shield ring. It is possible to realize an induction heating type rice cooker having a shield effect.

Further, the fourth means of the present invention is, in particular, the third means.
The current and phase supplied to the heating coil in the shield ring of
The induction heating type rice cooker with a higher shield effect can be realized by supplying high-frequency currents different by 180 °.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an induction heating type rice cooker that is a first embodiment of the present invention.

FIG. 2 is an explanatory view showing an induction heating type rice cooker that is a third embodiment of the present invention.

FIG. 3 is an explanatory view showing an induction heating type rice cooker which is a fourth embodiment of the present invention.

FIG. 4 is an explanatory diagram showing observation points for measuring magnetic field strength due to leakage magnetic flux.

FIG. 5 is an explanatory diagram illustrating a conventional induction heating rice cooker.

FIG. 6 is a plan view for explaining the arrangement of ferrite cores.

[Explanation of symbols]

 1 pan 2 heating coil 3 ferrite core 4a first shield ring 4b second shield ring 4c third shield ring 5 high frequency power supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Omori 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A pot for containing rice and water, a heating coil for generating a high-frequency magnetic field to induction-heat the pot, and a magnetic shield means for preventing the high-frequency magnetic field generated by the heating coil from leaking out of the apparatus. The induction heating rice cooker, wherein the magnetic shield means comprises a ferrite core and two shield rings provided in the vicinity of the heating coil and having a substantially circular cross section. 2. The induction heating type rice cooker according to claim 1, wherein the shield ring has a diameter of a second shield ring arranged below the device larger than a diameter of a first shield ring arranged above the device. vessel. 3. The induction heating type rice cooker according to claim 1, wherein the shield ring is only a third shield ring thicker than the diameter of the second shield ring described in claim 2. 4. The induction heating rice cooker according to claim 3, wherein a high frequency current having a phase difference of 180 ° from the current supplied to the heating coil is supplied to the third shield ring.