JP3101525B2 - Induction 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 induction heating rice cooker for cooking rice by heating by electromagnetic induction.

[0002]

2. Description of the Related Art An induction heating rice cooker utilizing electromagnetic induction has an excellent rice cooking function and is widely used. FIG. 4 is a schematic sectional view showing the structure of a conventional induction heating rice cooker of this type, FIG. 5 is a top view of the induction heating rice cooker, and FIG. 6 is a plan view of an induction heating coil shown together with ferrite. In the outer case 2 of the induction heating rice cooker 1, a pot body 3 which is a rice cooker,
An inner container 4 into which the shuttle main body 3 is fitted is housed.
The hook body 3 is formed by laminating a magnetic material such as iron or ferromagnetic stainless steel, which generates heat by magnetic flux, on the inner peripheral side of the inner peripheral side of an aluminum material. Inner container 4
Is made of a material through which magnetic flux passes, such as ceramic or heat-resistant resin, and is open at the top. One side of the upper part of the outer case 2
Near 2a, there is a control panel for specifying the content of cooked rice.

An upper lid 5 is mounted on the upper part of the outer case 2 and opens and closes on a side opposite to the upper side 2a. A steam outlet 5a is provided at the center of the upper lid 5. An inner cover 6 for opening and closing the upper opening 3a of the hook body 3 on a lower surface side of the upper cover 5 by a support fitting (not shown) attached to the upper cover 5.
Is installed. An induction heating coil holding plate 7 is provided below the inner container 4. Induction heating coil holding plate 7
Is made of a material through which magnetic flux can pass. As shown in FIG. 6, a pancake-shaped induction heating coil 8 having a predetermined number of turns is disposed on the upper surface of the induction heating coil holding plate 7, and a long dimension is provided on the lower surface side of the induction heating coil holding plate 7. A rectangular parallelepiped ferrite 9 whose direction is along the radial direction of the induction heating coil 8
Are equally arranged in the circumferential direction of the induction heating coil 8. Outer end of each ferrite 9 is the innermost part of induction heating coil 8,
It extends from the outer peripheral edge by a predetermined length, and faces the inside of the hook body 3 at a position closer to the outer periphery. Ferrite 9, 9 (see Fig. 4)
An inverter circuit for driving the induction heating coil 8 and a control circuit section 10 for controlling the inverter circuit in accordance with the temperature of the shuttle main body 3 are provided below the heater.

Next, the rice cooking operation of the induction heating rice cooker will be described. The upper lid 5 is opened, the pot body 3 in the inner container 4 is taken out, and predetermined amounts of rice and water necessary for rice cooking are put into the pot body 3. When the pot body 3 containing rice and water is fitted into the inner container 4 and the upper cover 5 is closed, the upper opening 3a of the pot body 3 is closed by the inner cover 6. After that, when the control panel is operated to perform the predetermined rice cooking operation, the control circuit section
10 starts the control operation and energizes the induction heating coil 8.
As a result, a magnetic flux is generated in the induction heating coil 8, and the generated magnetic flux φ is guided and concentrated by the ferrites 9, 9, 9, 9, for example, as shown by arrows, for example, the outer ends of the ferrites 9, 9, 9, 9, 9 Then, the light enters the outer peripheral side of the bottom 3b of the shuttle main body 3 through the bottom portion, passes through the bottom 3b, and enters the inner end of the ferrites 9, 9, 9, 9 from the inner peripheral side of the bottom 3b of the shuttle main body 3. Thereby,
An eddy current is generated at the bottom 3b of the shuttle main body 3, and the Joule heat causes the bottom 3b to generate heat, thereby heating the shuttle main body 3. Therefore, convection of the water put together with the rice occurs in the pot main body 3, and the rice cooker performs the rice cooking operation. Then, when a predetermined rice cooking time has elapsed, the power supply to the induction heating coil 8 is stopped, and the rice cooking operation ends.

[0005]

As described above, the induction heating coil in the conventional induction heating rice cooker is wound in a pancake shape, and a plurality of ferrites are provided below the induction heating coil in the circumferential direction of the induction heating coil. Arranged at an appropriate distance, the magnetic flux generated by the induction heating coil is concentrated on the ferrite and guided to the bottom of the pot body. Therefore, of ferrite,
Magnetic flux concentrates on the bottom of the pot body facing the outer end, and the pot body is locally heated, the heating temperature of the pot body becomes uneven, and heating unevenness occurs, depending on the cooking state, and the cooked rice is burned. There is a problem that there is a risk of occurrence. In view of such a problem, an object of the present invention is to provide an induction heating rice cooker which can reduce heating unevenness of a pot body and does not cause burns on cooked rice.

[0006]

According to a first aspect of the present invention, there is provided an induction heating rice cooker in which an induction heating coil is energized to heat a pot body to cook rice, wherein the induction heating coil extends radially. It has a plurality of coil extension parts which project, and a magnetic body is arranged at the base of an adjacent coil extension part.

The induction heating rice cooker according to the second invention is characterized in that the coil extension is provided in a cross shape. An induction heating rice cooker according to a third invention is characterized in that the coil extension is provided in a star shape. An induction heating rice cooker according to a fourth invention is characterized in that the outer end position of the magnetic body is selected to be the radius of the maximum position of the envelope of the coil extension.

[0008]

According to the first aspect of the invention, the induction heating coil is formed by radially providing the coil extending portions. A magnetic body is provided at the base of the adjacent coil extension. The magnetic flux passing through the magnetic material is incident on the inner periphery of the bottom of the hook body and heats the inner periphery of the bottom. Also,
The magnetic flux generated on the coil extension side is incident on the bottom outer periphery of the hook body and heats the bottom outer periphery. At the bottom portion of the shuttle main body facing between the coil extension portions adjacent to each other, the heat on the outer peripheral side of the heated inner portion is conducted and heated. Thus, uneven heating at the bottom of the shuttle main body can be reduced.

In the second invention, the position corresponding to the cross near the outer periphery of the bottom of the shuttle main body is heated by arranging the coil extension portion in a cross shape.

In the third aspect of the present invention, the coil extension is arranged in a star shape, thereby heating the position corresponding to the star shape near the outer periphery of the bottom of the shuttle body.

In the fourth invention, the position of the outer end of the magnetic body is
By selecting the radius at the maximum position of the envelope of the coil extension, the position closer to the outer periphery of the bottom of the hook body is heated more strongly.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic sectional view of a heating structure of an induction heating rice cooker according to the present invention. The pot main body 3, which is a rice cooker, is made of a clad material in which a stainless steel material or an iron material is laminated on the outer surface side of an aluminum material. The hook main body 3 has an upper opening 3a. Bottom of hook body 3
A cross-shaped induction heating coil 8 to be described later is provided below 3b, and a ferrite 9 which is a rectangular parallelepiped magnetic body is located on the lower surface side of the induction heating coil 8 near the inner periphery of the pot body 3. It is arranged.

FIG. 2 is a schematic plan view showing the arrangement of the induction heating coil 8, the ferrite 9, and the shuttle main body 3. The induction heating coil 8 is wound with a predetermined number of turns so as to bend the conductor W to form a cross. Thereby, the induction heating coil 8 is formed with four U-shaped coil extending portions 8a, 8b, 8c, 8d extending radially from the center thereof. The coil extensions 8a, 8b, 8c, 8d have the same dimensions and shape, respectively. Two coil extensions 8a, 8c or 8b, 8 symmetrically arranged
The length between the tips of d is slightly shorter than the diameter of the hook body 3. Adjacent and continuous coil extension 8
a, 8b, the coil extension portions 8b, 8c, the coil extension portions 8c, 8d, and the coil extension portions 8d, 8a. A rectangular parallelepiped ferrite 9 is provided on the lower side.

The outer end of each of the ferrites 9, 9, 9, 9 is selected to have the radius of the maximum position of the envelope of the induction heating coil 8, and the inner end is the minimum position of the envelope of the induction heating coil 8. Is selected at a radius dimension position that is approximately 1/2 of the radius dimension of. The inner and outer ends of the ferrites 9, 9, 9, 9 extend from the innermost and outer peripheral edges of the induction heating coil 8 by a suitable length. In this way, the outer end of the ferrites 9, 9, 9, 9 is positioned so as to face the inner periphery of the bottom 3b of the shuttle body 3.

The induction heating coil 8 can be manufactured by winding a predetermined number of turns concentrically around a conductor W along the outer periphery of a cross-shaped mold (not shown). Alternatively, the conductor W is wound in a pancake shape for a predetermined number of turns, and a cross-shaped form is arranged on the inner peripheral side of the wound coil, and the wound coil is placed inside the coil so as to follow the form from the outer peripheral side. It can also be manufactured by pressing and deforming to the peripheral side.

Next, the heating operation of the induction-heated rice cooker thus configured will be described. When the induction heating coil 8 is energized, the magnetic flux φ _i generated by the induction heating coil 8 facing the inner periphery of the pot main body 3 is concentrated on each ferrite 9 as shown in FIG. _i is the bottom of hook body 3
The light enters near the inner periphery of 3b and enters the ferrite 9 from the bottom 3b. As a result, an eddy current is generated near the inner periphery of the bottom portion 3b of the hook body 3, and the Joule heat causes the inner peripheral side of the bottom portion 3b of the hook body 3 to heat, thereby heating the hook body 3. The magnetic flux φ _o generated at the coil extension portions 8a, 8b, 8c, 8d is
Of the coil extension portions 8a, 8b, 8 from the bottom 3b.
Incident at c, 8d. As a result, an eddy current is generated near the outer periphery of the bottom portion 3b of the hook body 3, and the Joule heat causes
The outer peripheral side of the bottom 3b generates heat and heats the shuttle main body 3.

Since the coil extension portions 8a, 8b, 8c, 8d are long and have a large conductor area, the electromagnetic coupling force between the coil extension portions 8a, 8b, 8c, 8d and the shuttle main body 3 is large. The amount of heating near the outer periphery of the bottom 3b is large. The position near the outer periphery of the bottom 3b of the shuttle main body 3 that is not opposed to the coil extension portions 8a, 8b, 8c, 8d is generated by the magnetic fluxes φ _i , φ _{o in} the bottom 3b of the shuttle main body 3 near the outer periphery. It is heated by the conducted heat conduction. Therefore, the heat generation position is increased, and the bottom 3b of the pot body 3 can be uniformly heated, so that the heating unevenness is reduced and the cooked rice does not burn.

If the number of coil extensions 8a, 8b, 8c, 8d is further increased, and the number of ferrites 9 is increased accordingly, the bottom 3b of the hook body 3 can be heated even more evenly. it can.

FIG. 3 is a schematic plan view showing another embodiment of the induction heating coil 8, showing the arrangement of the induction heating coil 8, the ferrite 9, and the shuttle body 3. As shown in FIG. The induction heating coil 8
The conductor W is bent into a Y-shape (star shape) and wound with a predetermined number of turns. Thereby, the induction heating coil 8
Are formed with U-shaped coil extending portions 8j, 8k, 8l extending radially from the center thereof. The coil extensions 8j, 8k, 8l have the same size and shape. The coil extension portions 8j, 8k, 8l are so selected that their respective tip positions do not protrude from the outer periphery of the hook body 3. And coil extension parts 8j, 8k which are adjacent and continuous
Base side, coil extension part 8k, 8l base side, coil extension part
A rectangular parallelepiped ferrite 9 is disposed below the induction heating coil 8 on the base side of the tubes 8l and 8j. Ferrite 9, 9,
The outer end of each of 9, 9 is selected to have a radius at the maximum position of the envelope of the induction heating coil 8, and the inner end is approximately 1/2 of the radius of the minimum position of the envelope of the induction heating coil 8. Is selected at the radial position.

The outer ends of the ferrites 9, 9, 9 are positioned so as to face the inner periphery of the bottom 3b of the shuttle body 3. The induction heating coil 8 can be manufactured by winding the conductor W concentrically along the outer peripheral surface of the Y-shaped mold frame as described above. Alternatively, a Y-shaped mold (not shown) is provided on the inner peripheral side of the induction heating coil 8 wound in a pancake shape, and the induction heating coil 8 is pressed from the outer peripheral side along the mold and deformed. Can also be manufactured.

When the Y-shaped induction heating coil 8 is used, the bottom of the hook body 3 is uniformly heated in the same manner as when the cross-shaped induction heating coil 8 is used. There is no burn on cooked rice. In this embodiment,
Although the ferrite 9 is arranged below the induction heating coil 8,
A magnetic material other than ferrite may be used.

[0022]

As described in detail above, according to the first aspect of the present invention, the magnetic flux from the magnetic material heats the inner periphery of the bottom of the hook main body, and the magnetic flux generated in the coil extension portion causes the bottom of the hook main body to heat. By heating the outer periphery, the bottom of the pot body can be uniformly heated. This makes it possible to provide an induction heating rice cooker in which uneven heating at the bottom of the pot body is reduced and the cooked rice does not burn. According to the second invention, by forming the induction heating coil in a cross shape, according to the third invention, by forming the induction heating coil in a star shape, it is possible to uniformly heat the bottom of the pot body, According to the fourth aspect of the present invention, an induction-heated rice cooker that does not cause burns or the like on cooked rice can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a heating structure of an induction heating rice cooker according to the present invention.

FIG. 2 is a schematic plan view showing an arrangement state of an induction heating coil, a ferrite, and a pot body.

FIG. 3 is a schematic plan view showing an arrangement of induction heating coils, ferrites, and a hook main body having different shapes.

FIG. 4 is a schematic sectional view of a conventional induction heating rice cooker.

FIG. 5 is a top view of a conventional induction heating rice cooker.

FIG. 6 is a schematic plan view showing an arrangement of induction heating coils and ferrite used in a conventional induction heating rice cooker.

[Explanation of symbols]

 3 Hook body 3b Bottom 8 Induction heating coil 8a, 8b, 8c, 8d Coil extension 9 Ferrite (magnetic material) W conductor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A47J 27/00 103 H05B 6/12 308

Claims (4)

(57) [Claims] 1. An induction heating rice cooker for heating an electric kettle body to cook rice by energizing the induction heating coil, wherein the induction heating coil has a plurality of coil extension portions extending radially. An induction heating rice cooker, wherein a magnetic body is disposed at a base of an adjacent coil extension. 2. The induction heating rice cooker according to claim 1, wherein the coil extension portion is provided in a cross shape. 3. The induction heating rice cooker according to claim 1, wherein the coil extension is provided in a star shape. 4. The method according to claim 1, wherein an outer end position of the magnetic body is selected to be a radius of a maximum position of an envelope of the coil extension. Induction heating rice cooker.