JP3173995B2 - Induction heating rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an induction heating rice cooker,
In particular, the present invention relates to an induction heating rice cooker capable of uniformly heating an inner pot.

[0002]

2. Description of the Related Art In an induction heating type rice cooker, a protective frame is provided inside an outer casing, and an inner pot is housed therein so as to be able to be taken out. An induction heating coil is provided on the bottom surface of the protection frame so that the inner pot is induction-heated. The induction heating coil is spirally wound except for the central part, and a plurality of ferrites are provided below the central part radially from the central part toward the outer diameter side.

[0003] In the induction heating type rice cooker having the above-described structure, when the coil diameter of the induction heating coil is reduced, the magnetic coupling with the pot is reduced, and the material effect is small. A space having a predetermined diameter is formed. For this reason, the lines of magnetic force generated by energization become non-uniform, and the temperature of the inner pot is low at the center and high at the middle as shown in FIG. this is,
In order to cause uneven rice cooking, the inner pot is conventionally made to have a uniform temperature by various means as described below.

(1) A magnetic shield is provided between the bottom surface of the protective frame and the induction heating coil to suppress the magnetic flux density at the intermediate portion (see Japanese Patent Application Laid-Open No. 4-319317).

(2) The induction heating coil is wound separately on the inner diameter side and the outer diameter side (see Japanese Patent Application Laid-Open No. 4-322617).

(3) In the intermediate portion, the distance between the induction heating coil and the inner pot is increased (for example, actual open flat 6-1372).
No. 0).

[0007]

[Problems to be solved by the invention]
In the means of (1) and (3), a part of the generated magnetic field lines is not used for heating the inner pot, so that the temperature distribution of the inner pot is made uniform, so that a large amount of power is wasted.

In the method (2), the winding operation of the induction heating coil is difficult, and the heating ability is inferior to the conventional one.

In the means (3), the inner pot and the like must be formed in a special shape, and it is difficult to wash the inner pot. In addition, a case where a desired temperature distribution cannot be obtained due to easy deformation is also assumed.

Therefore, an object of the present invention is to provide an induction heating rice cooker that can efficiently heat an inner pot at a uniform temperature.

[0011]

In order to achieve the above object, according to the present invention, a protective frame, an inner pot accommodated in the protective frame, and a spirally wound state around the bottom surface of the protective frame are provided. Provided, a coil for induction heating the inner pot, and an induction heating rice cooker including a plurality of rod-shaped ferrites radially attached below the coil, apart from the ferrite, made of a high magnetic permeability material A shaft member is provided so as to penetrate a space formed at a winding center of the coil, and the coil is wound around the shaft member.

According to the above configuration, when the induction heating coil is energized, the generated magnetic lines of force are strengthened by the ferrite below the protective frame. In addition, since the shaft member around which the coil is wound is disposed at the center of the coil, the magnetic coupling is also strengthened at this position. Therefore, a desired number of magnetic fluxes can be generated even in the central portion of the bottom surface of the inner pot, and the temperature does not decrease as compared with other portions.

In order to achieve the above object, according to the present invention, there is provided a protective frame, an inner pot accommodated in the protective frame, and a spirally wound state disposed on a bottom surface of the protective frame. In an induction heating type rice cooker having a coil for induction heating an inner pot and a plurality of rod-shaped ferrites radially attached below the coil, a shaft member made of an iron-based metal material having a large electric resistance is provided by the coil The coil is wound around the shaft member and is directly in contact with the center of the bottom surface of the inner pot.

According to this configuration, the shaft member itself is heated by energizing the induction heating coil, and the heat directly heats the central portion of the bottom surface of the inner pot.

In order to achieve the above object, according to the present invention, a protective frame, an inner pot accommodated in the protective frame, and a spirally wound state on the bottom surface of the protective frame are provided. In an induction heating type rice cooker provided with a coil for induction heating of an inner pot and a plurality of rod-shaped ferrites radially attached below the coil, the coil has an elliptical cross section at a coil winding intermediate portion. Thus, the winding density of the conductive wire at the coil winding intermediate portion is reduced. With this configuration, it is possible to suppress heat generation at a portion corresponding to the center of the coil winding on the bottom surface of the inner pot, and to uniformly heat the inner pot.

In this case, it is preferable that the ferrite is provided on the inner diameter side and the outer diameter side so as to be separated from each other, since the heat generation at the portion corresponding to the center of the coil winding can be further suppressed.

[0017] In order to achieve the above object, the present invention provides an induction heating rice cooker comprising a bottomed tubular protective frame made of a heat-resistant material, and an inner pot accommodated in the protective frame. An induction heating coil disposed on the outer periphery of the side surface of the protection frame and induction heating the side surface of the inner pan, and an electric heater disposed on the bottom upper surface of the protection frame and directly heating by contacting the bottom surface of the inner pan. This is a configuration provided with. With this configuration, it is possible to uniformly perform heating on the bottom surface of the inner pot in which temperature unevenness is likely to occur.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a sectional view of an induction heating type rice cooker according to a first embodiment. In this induction heating type rice cooker, generally, a protective frame 2 is mounted in an exterior body 1 and an inner pan 3 is housed in the protective frame 2 so as to be able to be taken out.
Can be opened and closed by the lid 4.

The protective frame 2 has a cylindrical shape with a bottom, and as shown in FIG.
A recess 5 is formed in the center of the bottom surface. A plurality of projections 6 are erected downwardly around the recess 5. The tip of each projection 6 has a locking recess 7 on the inner diameter side, and is elastically deformable on the outer diameter side. The protective frame 2
The bottom surface of the induction heating coil 8 around the recess 5
Are spirally wound from the inner side to the outer side at two locations on the inner and outer circumferences. The recess 5 of the protective frame 2
Is provided with a columnar shaft member 9 made of ferrite. The induction heating coil 8 on the inner diameter side is continuously wound around the shaft member 9. At the lower end of the shaft member 9,
A flange portion 10 is formed which gradually decreases in diameter as going upward. Thus, when the shaft member 9 is pushed into the inner diameter side of each projection 6, the tip of each projection 6 can be gradually elastically deformed toward the outer diameter side on the inclined surface of the flange portion 10. Then, when the shaft member 9 is pushed into the predetermined position, the flange portion 10 is locked in the locking concave portion 7 and the projections 6 return to their original positions, so that they can be attached to the protection frame 2. Has become. The protective frame 2
Are provided with a plurality of ferrites 11 radially around the recess 5. The shaft member 9 and the flange 10
May be divided into separate parts, and the flange 10 may be made of a material other than ferrite.

In the induction heating type rice cooker, when the induction heating coil 8 is energized, lines of magnetic force are generated around the coil. The lines of magnetic force are strengthened in magnetic coupling on the bottom surface side of the protective frame 2 by the ferrite 11, and leakage of magnetic flux downward and to the side is prevented. In addition, the shaft member 9 around which the induction heating coil 8 is wound can enhance the magnetic coupling even at the center of the protective frame 2. Moreover, since the shaft member 9 is located near the bottom surface of the inner pot 3 by the recess 5, the central portion of the bottom surface of the inner pot 3 can be intensively heated. Therefore, the amount of heating at the middle portion of the inner pot 3 at the inner and outer circumferences is not suppressed by a magnetic shield plate or the like as in the related art, but as shown by a solid line in the graph of FIG. The temperature distribution of the inner pot 3 can be made uniform by increasing the amount of heating at the center of the inner pot 3.
Thereby, it is possible to obtain a favorable rice cooking state with low power consumption.

(Second Embodiment) FIG. 3 is a sectional view of an induction heating type rice cooker according to a second embodiment. In the first embodiment, the shaft member 9 is used to enhance magnetic coupling, whereas in the second embodiment, the inner pot 3 is directly heated by the shaft member 9. Is different.

That is, the shaft member 9 is made of an iron-based metal material, and as shown in FIG. 4, a support base 12 which is in direct contact with the center of the bottom surface of the inner pot 3 is formed in the upper part. In addition, a heat-resistant material is used for the protection frame 2, and a concave portion 13 that opens upward is formed at the center of the bottom surface. The shaft member 9
Is a concave portion 1 with the induction heating coil 8 wound around the outer periphery.
3 and screwed to the bottom surface of the protective frame 2. At this time, packing 14 is sandwiched between the support base 12 of the shaft member 9 and the protection frame 2 to prevent water or the like from entering the induction heating coil 8. The packing 14 is made of a material having excellent heat resistance such as silicon rubber.

In the induction heating type rice cooker, since a high-frequency current is applied to the induction heating coil 8, the shaft member 9 made of an iron-based metal material having a large electric resistance value generates heat directly due to the eddy current generated. The bottom center of the inner pot 3 is directly heated. As a result, similarly to the first embodiment, it is possible to perform heating at the central portion, which has conventionally been insufficient with the induction heating of the inner pot 3, so that appropriate rice cooking can be performed with a uniform temperature distribution.

(Third Embodiment) FIGS. 5A and 5B are a sectional view and a bottom view of an induction heating rice cooker according to a third embodiment. In this induction heating rice cooker,
The induction heating coil 8 is continuously wound without being separated at the inner and outer circumferences. In this case, in order to make the temperature of the inner pot 3 uniform, the winding density of the induction heating coil 8 is set to be low at the intermediate portion between the outer diameter side and the inner diameter side (coil winding intermediate portion). That is, since the induction heating coil 8 is formed by bundling a plurality of conductive wires and sealing the outer periphery, the winding of the conductive wire at the coil winding intermediate portion is formed by making the cross section elliptical at the coil winding intermediate portion. The density is sparse. According to this, since a gap is formed during the winding of the induction heating coil 8, a troublesome operation such as disposing a donut-shaped auxiliary member is not required, and the workability can be improved.

In the third embodiment, the ferrite 11 and the shaft member 9 are held by a holding member 15 screwed to the protection frame 2. The holding member 15 includes a bottomed cylindrical shaft member holding portion 16 and a ferrite holding portion 17 extending from the shaft member holding portion 16 at equal intervals in four directions. The shaft member holding portion 16 holds the shaft member 9 between the shaft member holding portion 16 and the upper bulging portion 2 a formed at the center of the bottom surface of the protection frame 2.
Further, the ferrite holding portion 17 is curved along the bottom surface shape of the protection frame 2, and the ferrite 11 is provided by integral molding or the like. As described above, according to the holding member 15, the shaft member 9 and the ferrite 11 are put together and the protection frame 2
And the induction heating coil 8 can be held, so that workability can be improved.

In the induction-heated rice cooker having the above-described structure, the conductive wire is sparse at the winding intermediate portion of the induction heating coil 8, so that the magnetic flux density at the intermediate portion of the inner pot 3 is suppressed. Also,
Each ferrite 11 is divided into two parts, and a space where no ferrite 11 exists is formed in the radially intermediate portion. As a result, the amount of heating in the intermediate portion of the inner pan 3 which has been overheated in the past is reduced, and the inner pan 3 is uniformly heated as shown by a dashed line in the graph of FIG. It is possible to obtain a preferable rice cooking state.

Fourth Embodiment FIGS. 6A and 6B are a sectional view and a bottom view of an induction heating type rice cooker according to a fourth embodiment. In this induction heating rice cooker,
The holding member 15 similar to that of the third embodiment is used for holding the ferrite 11. Further, the induction heating coil 8 is spirally wound separately at the inner and outer peripheries as in the first and second embodiments.

In the induction-heated rice cooker having the above-described configuration, the lines of magnetic force generated by energizing the induction heating coil 8 are weakened in the magnetic coupling at the space between the ferrites 11. As a result, similarly to the third embodiment, the amount of heating in the intermediate portion of the inner pot 3 which has been overheated in the past is reduced, and the inner pot 3 can be uniformly heated, and a preferable rice cooking state Can be obtained.

(Fifth Embodiment) FIG. 7 is a sectional view of an induction heating rice cooker according to a fifth embodiment. In this induction heating type rice cooker, the induction heating coil 8 is wound around the outer periphery of the side surface of the protection frame 2, and the electric heater 18 is arranged on the bottom upper surface of the protection frame 2. In this case, it is necessary to use a material having excellent heat resistance for the protective frame 2. According to this, since the bottom surface of the inner pot 3 can be directly heated by the electric heater 18, the temperature distribution does not become uneven.

[0031]

As is apparent from the above description, according to the induction heating type rice cooker according to the present invention, the shaft member is disposed at the center of the coil winding, and the coil is further wound around the shaft member. As a result, it is possible to sufficiently heat even the central portion of the inner pot. In particular, since the generated magnetic force lines can be effectively used for induction heating of the inner pot, it is possible to cook rice effectively without wasting power consumption.

Further, since the winding density is suppressed at the intermediate portion, the winding operation of the coil can be easily performed while uniformly heating the inner pot.

Further, since the ferrite is disposed separately at the inner and outer circumferences, the temperature of the inner pot can be easily made uniform without forming the inner pot or the like in a special shape, which is preferable. Can cook rice.

Furthermore, since only the side of the inner pot is induction-heated and the bottom is heated using a heater,
The inner pan can be heated even more evenly.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an induction heating rice cooker according to a first embodiment.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a sectional view of an induction heating rice cooker according to a second embodiment.

FIG. 4 is a partially enlarged view of FIG. 3;

FIG. 5 is a partial sectional view (a) and a bottom view (b) of an induction heating rice cooker according to a third embodiment.

FIG. 6 is a partial sectional view (a) and a bottom view (b) of an induction heating rice cooker according to a fourth embodiment.

FIG. 7 is a sectional view of an induction heating rice cooker according to a fifth embodiment.

FIG. 8 is a cross-sectional view of an inner pot and a graph showing a temperature distribution on the bottom surface of the inner pot.
(B) is a temperature distribution according to the present invention.

[Explanation of symbols]

 2 Protective frame 3 Inner pan 8 Induction heating coil 9 Shaft member

Continuation of the front page (56) References JP-A-5-207928 (JP, A) JP-A-49-86928 (JP, A) JP-A-60-105192 (JP, A) JP-A 9-135771 (JP) , A) JP-A-60-89 (JP, A) JP-A-1-315979 (JP, A) JP-A 5-1197 (JP, U) JP-A-8-500464 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) A47J 27/00 H05B 6/12

Claims (4)

(57) [Claims] 1. A protection frame, an inner pot accommodated in the protection frame, a coil disposed in a state of being spirally wound on a bottom surface of the protection frame, and a coil for induction heating the inner pot, and the coil And a plurality of rod-shaped ferrites radially attached below the induction heating rice cooker, wherein, apart from the ferrite, a shaft member made of a material having a high magnetic permeability is formed at the center of the winding of the coil. , And the coil is wound around the shaft member. 2. A protective frame, an inner pot accommodated in the protective frame, a coil disposed in a state of being spirally wound around a bottom surface of the protective frame, and a coil for induction heating the inner pot, An induction heating type rice cooker having a plurality of rod-shaped ferrites radially attached below a shaft, wherein a shaft member made of an iron-based metal material having a large electric resistance penetrates a space formed at a winding center of the coil. Wherein the coil is wound around the shaft member and brought into direct contact with the bottom center of the inner pot. 3. A protection frame, an inner pot accommodated in the protection frame, a coil disposed in a spirally wound state on the bottom surface of the protection frame, and a coil for induction heating the inner pot, and the coil. And a plurality of rod-shaped ferrites radially attached below the induction heating rice cooker, wherein the coil has an elliptical cross section at an intermediate portion of the coil to form a conductive wire at the intermediate portion of the coil. An induction-heated rice cooker characterized by a low winding density. 4. The induction-heated rice cooker according to claim 3, wherein the ferrite is provided on the inner diameter side and the outer diameter side so as to be separated from each other.