JPH1028645A - Induction heating rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize the temperature distribution of an inner pot by induction heating and provide a preferable cooking state by arranging ferrites in such a state as relatively rotating about the winding center of a coil in relation to the inner pot SOLUTION: A bottomed cylindrical protection frame 12 is arranged inside a rice cooker main body 11 and in induction heating coil 15 is arranged under the protection frame 12. Four ferrites 16 extending radially from the winding central side toward the bottom of the induction heating coil 15 at the same angle are arranged respectively. The ferrites 16 are held by a ferrite cover 17 and a rotary shaft 19a of a motor 19 is connected to the bottom center of the ferrite cover 17 so that the ferrites 16 are rotational moved in the circumferential direction of the inner pot 13 by the drive of the motor 19. This constitution can equalize the temperature distribution of the inner pot 13 by induction heating so as to provide a preferable cooking state.

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 suitable for uniform heating of an inner pot.

[0002]

2. Description of the Related Art Conventionally, in an induction heating type rice cooker, an inner pot 2 accommodated in a bottomed cylindrical protective frame 1 as shown in FIG.
Is supplied to the induction heating coil 3 spirally arranged on the bottom surface of the protection frame 1 to perform induction heating. A ferrite 4 is disposed below the induction heating coil 3 so that a magnetic field generated at the time of induction heating does not adversely affect the outside, particularly, the control device 5 disposed on the lower surface side.

[0003]

However, the ferrite 4 of the induction heating type rice cooker is fixed to the protective frame 1. For this reason, the lines of magnetic force generated at the time of induction heating are shown in FIG.
As shown in FIG. 7, as a result of being pulled toward the ferrite 4 side, it is biased in the circumferential direction. Therefore, on the bottom surface of the inner pot 2, as shown in the graph of FIG. 8, the temperature of a portion where the ferrite 4 is present is high, and the temperature of the portion where the ferrite 4 is not is low, so that a variation in the temperature distribution in the circumferential direction occurs. Moreover, this variation in the temperature distribution also occurs in the radial direction of the bottom surface of the inner pot 2 as shown in FIG. This is because the space of a predetermined diameter is formed at the center of the spiral of the induction heating coil 3, so that the lines of magnetic force generated by energization become non-uniform. This space in the central portion is necessary because the magnetic coupling with the pot is reduced when the coil diameter of the induction heating coil 3 is reduced, and the material effect is small. As a result, the temperature of the inner pot is low at the center and high at the middle, and there is a problem that a favorable rice cooking state cannot be obtained.

Accordingly, an object of the present invention is to provide an induction heating type rice cooker capable of obtaining a preferable rice cooking state by equalizing the temperature distribution of an inner pot by induction heating.

[0005]

In order to achieve the above object, according to the present invention, a bottomed cylindrical protective frame, an inner pot accommodated in the protective frame, and a spiral winding around the bottom surface of the protective frame are provided. An induction heating rice cooker, which is disposed in a rotated state and includes a coil for induction heating the inner pot, and a ferrite disposed below the coil from the winding center side toward the outer diameter side. In the above, the ferrite is disposed so as to be rotatable relative to the inner pot around a winding center of the coil. According to this configuration, when only the ferrite, only the inner pan, or both rotate, the lines of magnetic force move with the rotation, and the magnetic flux density at the bottom surface of the inner pan gradually changes in the circumferential direction. Thereby, the temperature distribution in the circumferential direction on the bottom surface of the inner pot becomes uniform.

[0006] In addition to the ferrite which rotates relatively to the inner pot, a ferrite having a fixed positional relationship with the inner pot may be provided. According to this configuration, the ferrite that rotates relatively to the inner pot disturbs the magnetic field generated by the ferrite in a fixed positional relationship, and enables uniform induction heating.

[0007] The ferrite may be provided separately at predetermined intervals in a radial direction. According to this configuration, the magnetic flux density can be made uniform not only in the circumferential direction but also in the radial direction, and uniform heating can be achieved.

It is preferable that the driving means for rotationally driving the ferrite is provided in a space below the protection frame, and the other main parts are provided in a space in front of the protection frame. According to this configuration, each component can be disposed by effectively using an extra internal space without increasing the size of the rice cooker itself.

[0009]

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

FIG. 1 is a schematic diagram of an induction heating rice cooker according to the present invention. This induction heating type rice cooker generally includes a rice cooker main body 11 and a bottomed cylindrical protective frame 1 disposed therein.
2 and an inner pot 13 which is removably accommodated in the protective frame 12
And a lid 14 for opening and closing the upper opening.

On the lower surface of the protective frame 12, an induction heating coil 15 is provided. This induction heating coil 15
The coil is spirally wound at two locations on the inner and outer circumferences.

As shown in FIG. 2, four ferrites 16 are provided below the induction heating coil 15 and extend radially from the center of the winding at an equal angle. Since the ferrite 16 is a magnetic material having a high magnetic permeability,
By focusing the magnetic lines of force generated from the induction heating coil 15,
Leakage to the lower side of the rice cooker body 11 is prevented. On the other hand, on the bottom surface of the inner pan 13, the magnetic flux density is affected by the ferrite 16, and the magnetic flux density varies in the circumferential direction.
6 is higher as the position is closer to the position opposite to 6.

The ferrite 16 is a ferrite cover 1
7. The ferrite cover 17 is dish-shaped, and its outer peripheral edge is held by a guide groove 18 provided on the inner peripheral surface of the outer shell 11a of the rice cooker main body 11, and is rotatable in the circumferential direction. However, the guide groove portion 18 may be provided over the entire circumference of the outer trunk 11a or may be provided partially (for example, into three equal parts, four equal parts, or the like). Further, a rotation shaft 19a of a motor 19 is connected to the center of the bottom surface of the ferrite cover 17. The ferrite 16 is rotationally moved in the circumferential direction with respect to the inner pot 13 by driving of the motor 19. Thereby, the lines of magnetic force generated on the bottom surface of the inner pan 13 move, and the magnetic flux density in the circumferential direction becomes uniform.

The drive of the motor 19 is controlled based on a control signal from a control device 20. This control device 20
Is the rice cooker body 1 together with the fan 21 for cooling
1 is disposed on the front side. Normally, the control device 20 and the fan 21 are arranged in the space below the protection frame 12, but the above-mentioned position secures a space for disposing the motor 19 without increasing the height of the rice cooker main body 11. It is possible to The control device 20 includes:
The temperature of the inner pot detected by the temperature sensor 22 protruding from below the side wall of the protection frame 12 is input. Control device 20
Controls the power supply to the induction heating coil 15 based on the inner pot temperature.

Reference numeral 23 denotes a liquid crystal panel for displaying the rice cooking status, time, and the like.

In the induction-heated rice cooker having the above configuration, the inner pot 1
When a predetermined amount of rice and water are stored in 3 and a rice cooker switch is operated, rice cooker control is started. The rice cooking control is performed by a preheating control process, a high heat control process, a low heat control process, and a steaming control process.

In the preheating control process at the beginning of the rice cooking, water is contained in the inner pot 13 in addition to rice, so that the internal temperature is less likely to vary due to convection regardless of the bottom temperature distribution of the inner pot 13. . However, if we shift to the high-fire control process,
The amount of water decreases due to water absorption and evaporation into the rice, resulting in a state in which convection is difficult or no convection. Thereby, inner pot 1
In the internal temperature of No. 3, there is a variation in the circumferential direction due to the influence of the ferrite 16. This variation in the temperature distribution has an adverse effect on the state of cooked rice and causes the flavor of the cooked rice to be impaired.

Therefore, the temperature detected by the temperature sensor 22 is a predetermined temperature, that is, the temperature at which it is determined that convection cannot be expected (or the temperature at which it is determined that convection cannot be expected due to the fact that the inner pan 13 is heated to reduce (or lose) moisture. When the temperature reaches a predetermined temperature before the temperature reaches the predetermined value, the motor 19 is driven to start the rotation of the ferrite 16. In this case, the ferrite 16 may be rotated at a constant speed, or may be stopped for a predetermined time every time the ferrite 16 is rotated by a fixed angle.

When the rotation of the ferrite 16 is started in this manner, the lines of magnetic force generated on the bottom surface of the inner pot 13 do not concentrate on a predetermined portion, and as shown by a solid line in FIG. The temperature distribution on the bottom surface becomes uniform. Therefore, the internal temperature of the inner pot 13 is not varied, and a favorable rice cooking state can be obtained. Then, when the high heat control process is completed, the process sequentially proceeds to the low heat control process and the steaming process, and the rice cooking control ends. The rice thus obtained can be heated uniformly in the high heat control process, so that the rice is delicious and excellent in flavor.

In the above embodiment, the ferrite 1
6 is arranged on the upper surface of the ferrite cover 17, but may be on any position such as the lower surface as long as it is arranged radially. The ferrite cover 17
May be various shapes other than the above-mentioned dish shape, such as a radial shape having only a portion for holding the ferrite 16.

The number of the ferrites 16 is not limited, and the length and the position of the ferrites 16 in the radial direction are also free. In this case, if the ferrite 16 is separately disposed on the inner and outer peripheral sides, the temperature distribution in the radial direction as well as the circumferential direction can be made uniform. That is, the temperature distribution on the bottom surface of the inner pot 13 is low at the central portion and the outer peripheral portion and is high at the intermediate portion, as shown by the two-dot chain line in FIG. Therefore, the ferrite 16 is provided separately in the radial direction so that the ferrite 16 is not located in the middle portion where the temperature becomes high, so that the temperature distribution in the radial direction is made uniform as shown by the solid line in FIG. be able to.

Further, the ferrite 16 may be not only a rotatable one but also a fixed one as in the prior art (see FIG. 5). The fixed ferrite 16 prevents the magnetic flux from leaking downward as in the prior art, and the rotating ferrite 16 disturbs the magnetic field generated in the inner pot 13 at that time to make it uniform. In this case, the rotating ferrite 1
6 may be only one.

The rotation time of the ferrite 16 is as follows.
As described above, it is needless to say that the present invention is not limited to the high-fire control process (so-called medium papper), but may be performed by other processes.

Further, in the above embodiment, the ferrite 16 is rotated, but the inner pot 13 may be rotated, or both may be rotated. The rotation may be normal or reverse within the range. In short, the magnetic field may be uniformly generated by relatively moving the positional relationship between the inner pot 13 and the ferrite 16.

[0025]

As is apparent from the above description, according to the induction heating type rice cooker according to the present invention, the ferrite is rotated to make the temperature distribution in the circumferential direction of the inner pot uniform, so that the rice cooker can cook rice. You can cook delicious rice without unevenness.

Further, since the ferrites having different lengths are arranged at random, the inner pot can be more uniformly heated.

In addition, since the ferrite is arranged at predetermined intervals in the radial direction, the ferrite can be heated not only in the circumferential direction of the inner pot but also in the radial direction, so that the rice can be heated more evenly. Can be cooked.

Further, the main parts other than the driving means for rotating the ferrite are arranged in the space in front of the rice cooker main body, so that the excess space in the rice cooker main body is effectively used to avoid size increase. Can be.

[Brief description of the drawings]

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

FIG. 2 is a bottom view of the inner pot of FIG. 1;

FIG. 3 is a graph showing a temperature distribution on a bottom surface of the inner pot of FIG. 2;

FIG. 4 is a graph showing a cross-sectional view of an inner pot and a temperature distribution.

FIG. 5 is a schematic sectional view of an induction heating rice cooker according to another embodiment.

FIG. 6 is a schematic sectional view of an induction heating rice cooker according to a conventional example.

FIG. 7 is a bottom view showing the magnetic flux density on the bottom surface of the inner pot of FIG. 6;

FIG. 8 is a graph showing a temperature distribution on the bottom surface of the inner pot of FIG. 6;

FIG. 9 is a graph showing a cross-sectional view and a temperature distribution of an inner pot according to a conventional example.

[Explanation of symbols]

 11 Rice Cooker Body 12 Protective Frame 13 Inner Pan 15 Induction Heating Coil 16 Ferrite 17 Ferrite Cover 19 Motor

Claims (4)

[Claims] A bottomed cylindrical protective frame, an inner pan accommodated in the protective frame, and a spirally wound state on the bottom surface of the protective frame, for induction heating the inner pan. In an induction heating type rice cooker comprising a coil and a ferrite disposed below the coil from a winding center side toward an outer diameter side, the ferrite is disposed around a winding center of the coil. An induction heating rice cooker, which is rotatably disposed relative to the inner pot. 2. The induction heating according to claim 1, wherein, in addition to the ferrite which rotates relatively to the inner pot, a ferrite having a fixed positional relationship with respect to the inner pot is provided. Rice cooker. 3. The induction-cooked rice cooker according to claim 1, wherein the ferrites are arranged separately at predetermined intervals in a radial direction. 4. The device according to claim 1, wherein the driving means for rotating and driving the ferrite is provided in a space below the protection frame, and the other main parts are provided in a space in front of the protection frame. 4. The induction-cooked rice cooker according to any one of items 1 to 3.