JPH10116681A - Induction heating cooking appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress leakage magnetic field from a non-circular heating coil by changing the distribution of magnetic material in accordance with the directionality of the magnetic field distribution of the heating coil, and thereby making the magnetic field distribution of the heating coil non-directional. SOLUTION: Four rod-shaped ferrite cores 8a, 8b, 8c, and 8d in the same shape are installed under a heating coil 6 in a position opposite the side where a cooking deep pan as a load is placed, in such a way that a space is reserved around the center of the coil 6. The angles formed by the ferrite cores 8a and 8b and ones 8c and 8d are made smaller than the angles formed by adjoining ferrite cores 8b and 8c and ones 8a and 8d, and the directionality of the magnetic field distribution generated by the heating coil 6 is mitigated. Thus the magnetic field distribution of the heating coil 6 having elliptical form is made non-directional, and thereby suppression is made for the tendency that the magnetic field leaking from the coil 6 to the periphery becomes intense in the specific direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker provided with magnetic shield means for reducing a magnetic field generated from a heating coil.

[0002]

2. Description of the Related Art In recent years, an induction heating cooker for inducing an eddy current at the bottom of a load pan by a high-frequency magnetic field for heating has been designed to have a high output, and accordingly, it has become necessary to suppress a magnetic field leaking to the surroundings. ing.

[0003] A conventional induction heating cooker will be described below. FIG. 9A is a plan view showing a configuration of a heating coil of a conventional induction heating cooker. The heating coil 1 is wound in an elliptical shape and placed on a heating coil holding table 2. FIG.
As shown in the cross-sectional view of (b), a top plate 4 is provided above the heating coil 1, and a load pan 5 is placed thereon.

On the lower surface of the heating coil holder 2, four substantially rectangular parallelepiped rod-shaped ferrite cores 3a to 3d having the same shape are provided.
Are respectively located near the outer periphery of the heating coil 1.
And the distance (angle) between the ferrites is substantially equal (equal angle), that is, the angle between the ferrite cores adjacent to each other is about 90 degrees.
Degree.

[0005] Further, the upper surface of the ferrite cores 3a to 3d,
The bonding is performed such that the distance from the lower surface of the heating coil 1 is substantially equal, and the distance from the inner peripheral edge of the heating coil 1 to the inner ends of the ferrites 3a to 3d is substantially equal. The heating coil holder 2 is fixed to the upper part of the housing of the induction heating cooker, and the heating coil 1 is arranged below the top plate 4 on which the load pan 5 is placed.

In the above configuration, when a high frequency current is supplied from the inverter to the heating coil 1, a magnetic field is generated from the heating coil 1, a magnetic flux is linked to the load pan 5 on the top plate 4, and an induction current is generated in the load pan 5. Then the load pan 5 is heated by Joule heat. Although a magnetic field is also generated below the heating coil 1, since the ferrite cores 3a to 3d are provided, the lower magnetic flux concentrates on the ferrite cores 3a to 3d.
Prevents the magnetic flux from spreading downward.

[0007]

In such a conventional induction heating cooker, when a high frequency current is supplied to the heating coil 1 and the magnetic field around the induction heating cooker is measured to connect the points of the uniform magnetic field, a flat surface is obtained. FIG. 10 shows an elliptical magnetic field distribution, and there is a problem that the leakage magnetic field in the major axis direction of the heating coil 1 becomes strong.

An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to suppress a magnetic field generated from an induction heating cooker having a non-circular heating coil from increasing in a specific direction.

[0009]

In order to achieve the above-mentioned object, the present invention is directed to an arrangement in which a center is located near a load and opposed to the load in a plane projection shape (substantially the center of the shape formed by the inner peripheral edge of the heating coil). A non-circular heating coil whose distance from the outer peripheral edge is not substantially constant, a frequency conversion device for supplying a high-frequency current to the non-circular heating coil, and a position near the non-circular heating coil opposite to the side where the load is located. A plurality of magnetic members disposed around the center of the non-circular heating coil and disposed substantially in the direction of the center from the vicinity of the outer periphery of the non-circular heating coil; and the directivity of the magnetic field distribution of the non-circular heating coil is provided. The distribution of the magnetic material is changed in accordance with the above, and the distribution of the magnetic field of the non-circular heating coil becomes a non-directional pattern.

[0010]

According to the first aspect of the present invention, when a high frequency current is supplied to a heating coil from a frequency converter, a surface constituting a winding of the heating coil (hereinafter referred to as a heating coil surface).
Generates magnetic flux on both sides of the load, and heats a load placed in the vicinity of one side. On the other hand, a plurality of magnetic materials such as a plurality of ferrite cores which are located near the heating coil on the opposite side to the side where the load is located, are provided around the center of the heating coil, and are arranged from the vicinity of the outer periphery of the heating coil to substantially the center. Therefore, the high-frequency magnetic flux generated on the side of the heating coil surface on which the magnetic body is provided concentrates on the magnetic body and suppresses the magnetic flux from spreading to spaces other than the load side.

Further, each magnetic body has an effect of reducing the magnetic field strength in the direction in which the magnetic body is disposed or in the direction opposite to the direction 180 degrees from the center of the heating coil. In addition, since the distribution density of the magnetic material in a specific direction when viewed from the center of the heating coil is higher than in other directions, the magnetic flux focused by the magnetic material increases in that direction, and the heating coil near that direction The level of suppression of the magnetic field intensity generated from the above can be made higher than in other directions. That is, the directivity of the magnetic flux distribution around the induction heating cooker can be changed by changing the distribution density of the plurality of magnetic substances depending on the direction.

On the other hand, since the heating coil has a non-circular shape in which the distance from the center to the outer peripheral edge is not constant in a planar projection shape, there is an advantage that the heating surface of the pot bottom serving as a load can be formed in a shape other than a circle. In the direction in which the distance from the center to the outer peripheral edge becomes longer, the magnetic field becomes stronger than in other directions, and the magnetic field distribution has directivity.

According to the magnetic field distribution having directivity depending on the shape of the heating coil, the distribution of the plurality of magnetic materials is changed so as not to be arranged uniformly, and the distribution of the magnetic field generated from the heating coil of the heating coil is changed. By adopting the mitigation means, it is possible to make the magnetic field strength close to almost isotropic, in which the magnetic field intensity does not greatly change depending on the direction, and it is possible to suppress the magnetic field from increasing in a specific direction of the induction heating cooker and reduce the leakage magnetic field. Is what you can do.

According to a second aspect of the present invention, a distance between one or more adjacent two magnetic bodies among a plurality of magnetic bodies, or
Since the angle to be formed is smaller than the distance between the other two adjacent magnetic bodies or the angle to be formed, and the directivity reducing means of the magnetic field distribution is provided by a non-circular heating coil which enhances the effect of suppressing the magnetic field distribution in a specific direction. , Alleviates the directivity of the magnetic field distribution caused by the shape of the non-circular heating coil to approach non-directionality,
An increase in the magnetic field in a specific direction can be suppressed.

According to a third aspect of the present invention, there is provided means for reducing directivity of a magnetic field distribution generated from the non-circular heating coil by changing a distribution density of the magnetic material in accordance with a distance from a center to an outer periphery of the heating coil. As a result, the directivity of the magnetic field distribution caused by the non-constant distance from the center of the non-circular heating coil to the outer peripheral edge is reduced to approach non-directionality, thereby suppressing the increase in the magnetic field in a specific direction. Can be done.

According to a fourth aspect of the present invention, the distance between one or more of the plurality of magnetic bodies and the non-circular heating coil is made smaller than the distance between the other magnetic bodies and the non-circular heating coil. In a specific direction, change the magnetic coupling between the other direction and the magnetic material and the non-circular heating coil to give directionality to the magnetic field focusing effect due to the arrangement of the magnetic material, and use that direction to make the non-circular heating coil The present invention can reduce the intensity of directivity in a specific direction in a magnetic field distribution caused by a non-circular shape, make the magnetic field distribution generated from the non-circular heating coil closer to an isotropic direction, and suppress a leakage magnetic field.

According to a fifth aspect of the present invention, the distance between one or more magnetic members of the plurality of magnetic members from the inner periphery of the non-circular heating coil is determined by comparing the distance from the position of the other magnetic members with respect to the outside of the heating coil. Shifting inward to change the relative positional relationship with the non-circular heating coil, changing the magnetic coupling between the magnetic material and the non-circular heating coil in the other direction in a specific direction, and converging the magnetic field by the arrangement of the magnetic material The effect has directionality, and by using the directionality, the directivity intensity in a specific direction in the magnetic field distribution associated with the non-circular shape of the non-circular heating coil is reduced, and the magnetic field distribution generated from the non-circular heating coil is reduced. It can approach the directionality and suppress the leakage magnetic field.

According to a sixth aspect of the present invention, the shape of at least one of the plurality of magnetic materials is made different from the shape of the other magnetic materials according to the directivity of the magnetic field distribution of the non-circular heating coil.
Giving directionality to the magnetic field focusing effect of the magnetic material, using the directionality of the magnetic field focusing effect to reduce the intensity of the directivity in a specific direction in the magnetic field distribution caused by the non-circular shape of the non-circular heating coil, The magnetic field distribution generated from the non-circular heating coil can be made closer to isotropic, and the leakage magnetic field can be suppressed.

According to a seventh aspect of the present invention, the directivity of the magnetic field distribution caused by the non-uniformity of the distance from the center to the outer periphery of the non-circular heating coil is determined by changing the length or the sectional area of the magnetic material arranged in a specific direction. Can be reduced by changing the shape of the non-circular heating coil, the distribution of the magnetic field generated from the non-circular heating coil can be made closer to isotropic, and the leakage magnetic field can be suppressed.

According to the eighth aspect of the present invention, there is provided a conductive member for magnetic shield, which is provided in the vicinity of the outer periphery of the non-circular heating coil and generates an induced current by a magnetic flux generated by the non-circular heating coil. Since the magnetic flux generated from the conductive wire member enhances the leakage magnetic flux reduction effect, and by changing the shape of the conductive member for magnetic shield and the distance between the non-circular heating coil, the directivity can be reduced, Along with the directivity relaxation effect of multiple magnetic materials,
It is possible to more effectively reduce the intensity of the directivity in a specific direction in the magnetic field distribution associated with the non-circular shape of the non-circular heating coil, or to easily reduce the leakage magnetic flux.

[0021]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

As shown in the plan view of FIG.
Are fixed on the coil holder 7, and four ferrite cores 8 a, 8 b, 8 c, 8 d made of ferrite having a high magnetic permeability and a magnetic flux focusing effect and having a substantially rectangular parallelepiped shape are adhered and fixed to a lower portion of the coil holder 7. ing. 2, a top plate 9 and a load pan 10 are arranged above the heating coil 6. As shown in FIG.

In FIG. 1, the angle between ferrite core 8a and ferrite core 8b and the angle between ferrite core 8c and ferrite core 8d are 70 degrees, the angle between ferrite core 8b and ferrite core 8c, and the angle between ferrite core 8a and ferrite core 8c. The angle made by 8d is 110
Degrees.

The operation of the induction cooking device configured as described above will be described. When a high frequency current is supplied from the inverter to the heating coil 6, a magnetic field is generated from the heating coil 6, and the magnetic field interlinks with the bottom of a metal load pan 10 made of iron or the like placed on the top plate 9, causing a vortex. An electric current is generated, and the bottom of the load pan 10 generates heat due to Joule heat.

The lines of magnetic force generated from the heating coil 6 are linked to the bottom of the load pan 10 above the heating coil 6, and the ferrite cores 8 a to 8 d below the heating coil 6.
Focus on In order to measure the leakage magnetic field around the equipment, a loop antenna is used, and the heating coil 6 and the loop antenna are installed at a height of about 1 m from the ground,
At a point 3 m away from the device, a loop antenna is installed vertically on the ground, and the maximum magnetic field strength of the inverter at a fundamental oscillation frequency of 25 kHz is measured by the loop antenna while rotating the device, as shown by a solid line B in FIG. Omnidirectional magnetic field distribution, which becomes almost constant depending on the direction of.

In FIG. 3, the length from the center corresponds to the measured magnetic field strength, the angle corresponds to the rotation angle of the device,
The device is set to 0 degree when the front side of the sectional view of FIG. 2 faces the direction of the loop antenna, that is, the ferrite core 8 of FIG.
a between the direction of a and the direction of the ferrite core 8d is 0.
In degrees, the angle is a clockwise rotation about the center of the heating coil 6 as a center, and the magnetic field strength is plotted by measuring the maximum magnetic field strength that can be measured by rotating the loop antenna.

In FIG. 3, the measurement results of the horizontal magnetic field distribution indicated by the broken line A are those of the conventional configuration shown in FIGS. 9 (a) and 9 (b), and the ferrite cores 3a to 3d are evenly distributed. In this case, the heating coil 1 is disposed around the center of the heating coil 1 with a suitable angular interval. In this case, the magnetic field in the directions of 90 degrees and 270 degrees when viewed from the center of the heating coil 1 has a strong directional distribution. On the other hand, the solid line B in FIG. 3 shows the measurement result of the magnetic field distribution in the configuration shown in FIGS. In this case, the magnetic field intensity hardly changes depending on the direction, and the omnidirectionality is slightly increased in the directions of 0 degree and 180 degrees as compared with the case of the conventional configuration indicated by the broken line A in FIG. Is 9
Leakage magnetic fields in the directions of 0 and 270 degrees are greatly reduced.

When the ferrite core is arranged with a uniform angular difference around the center of the heating coil 1 as shown in FIG. 9A, when the heating coil 1 is incorporated in the housing, the heating coil 1 If there is nothing that disturbs the magnetic field distribution, the shape of the heating coil 1 is elliptical, so that the magnetic field distribution becomes elliptical, the magnetic field in the major axis direction of the ellipse becomes strong, and a directional magnetic field distribution is obtained.

In FIG. 1, however, the angle formed by the center lines of ferrite cores 8a and 8b and the angle formed by the center lines of ferrite cores 8c and 8d are determined by the respective center lines of ferrite core 8b and ferrite core 8c. And the angle formed by the center lines of the ferrite cores 8a and 8d, the distribution density of the ferrite core is larger in the major axis direction than in the minor axis direction when viewed from the center of the elliptical heating coil 6. Becomes larger. As a result, the magnetic flux focusing effect of the ferrite core is increased in that direction, the horizontal magnetic field distribution in the major axis direction is reduced, and a distribution with almost no directivity can be obtained.

As described above, according to the present embodiment, the loading pan 1
In the vicinity of the heating coil 6 on the side opposite to the side where 0 is located, that is, in the vicinity of the lower side of the heating coil 6, four substantially identical rod-shaped ferrite cores arranged at intervals around the center of the heating coil 6 The angles formed by the cores 8a and 8b and the ferrite cores 8c and 8d are determined by the combination of other adjacent ferrite cores, that is, the ferrite cores 8b and 8c.
And the ferrite cores 8a and 8d are made smaller than the angle formed by each of the ferrite cores 8a and 8d. By providing the directivity reducing means for the magnetic field distribution, the horizontal magnetic field distribution of the magnetic field leaking from the heating coil 6 to the periphery of the device can be made closer to non-directionality, thereby suppressing the leakage magnetic field.

Basically, if the distribution density of the ferrite core is increased according to the distance from the center to the outer periphery of the heating coil 6 as described above, that is, as the distance increases, the directivity of the magnetic field distribution of the heating coil 6 increases. Sex is eased.

On the other hand, the directivity of the magnetic field distribution from the heating coil 6 is also caused by the influence of the metal housing and the internal components constituting the device. By changing the angle between the ferrite cores, it is possible to approximate the omnidirectional magnetic field distribution,
The leakage magnetic field can be easily suppressed.

Further, if the total number of ferrite cores is increased, the directivity can be delicately changed, and may be increased or decreased as needed.

The angle between the ferrite cores is the angle formed by the center lines of the ferrite cores when viewed from above the heating coil. The distribution density of the magnetic material may be increased. Even if the intervals between the ferrite core and the heating coil are not all uniform, by adjusting the angle between the ferrite cores, the distribution of the magnetic field generated from the heating coil can be made closer to non-directionality and the leakage magnetic field can be suppressed. Even if the shape of the ferrite core is not always constant, the magnetic field generated by the heating coil can be suppressed by adjusting the angle between the ferrite cores similarly.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to FIGS. FIG.
It is a sectional side view in A '. The difference from the first embodiment is that the four ferrite cores have the same angular interval (90 degrees).
And two ferrite cores 13b, 1 provided below the heating coil 11 and located in the major axis direction of the elliptical shape.
The distance between the upper surface of 3d and the lower surface of the heating coil 11 is h1 = 2
mm Ferrite cores 13a and 13c located in the minor axis direction
Distance between the upper surface of the heating coil 11 and the lower surface of the heating coil 11 is h2 = 4 mm
In order to secure the distance between the heating coil 11 and the core, the thickness of the coil holder 12 is partially different, and the thickness of the coil holder 12 at the bonding portion between the ferrite cores 13a and 13c is reduced. Ferrite cores 13b, 13d
It is thicker than the bonded part. Other configurations are the same as those in FIGS. 1 and 2 of the first embodiment.

In the above configuration, the two ferrite cores 13b and 13 in the major axis direction of the elliptical heating coil 11 are provided.
Since the distance between the heating coil 11 and the heating coil 11 is smaller than the distance between the ferrite cores 13a and 13c and the heating coil 11 in the minor diameter direction, the heating coil 11 and the ferrite core 13b and 1
The magnetic coupling between 3d and heating coil 11 is stronger than the magnetic coupling between ferrite cores 13a and 13c and heating coil 11. When the magnetic coupling state between the ferrite core and the heating coil 11 becomes strong, the number of the heating coils 11 converging on the ferrite core increases, so that the magnetic flux in the direction of the major axis as viewed from the center of the elliptical heating coil 11 moves in the surrounding horizontal direction. Spreading can be suppressed.

As described above, according to the present embodiment, the radially uniform angular interval around the center of the heating coil 11 near the heating coil 11 on the side opposite to the side where the load pan is located, ie, near the lower side of the heating coil 11. Of the four ferrite cores having substantially the same shape and arranged with ferrites, the ferrite cores 13b, 1 located in the major axis direction of the elliptical heating coil 11 are provided.
The relative positional relationship between the heating coil 11 and the ferrite cores 13a and 13c located in the minor diameter direction (in this case, the distance between the two) is determined. (In this case, smaller), the magnetic coupling state between the ferrite core in the long diameter direction and the heating coil 11 is made stronger than the magnetic coupling state between the ferrite core in the short diameter direction and the heating coil 11. Therefore, the same effect as in the first embodiment in which the angle between the ferrite cores in the specific direction is narrowed and the distribution density of the ferrite cores in the specific direction is increased can be obtained. Therefore, since the heating coil 11 has an elliptical shape, the magnetic field strength in the major axis direction is suppressed from increasing, and the leakage magnetic field can be suppressed by approaching the non-directional magnetic field distribution.

In the second embodiment, the ferrite cores having the same shape at the same angle are used. However, the present invention is not limited to this, and the ferrite cores having the same shape may not be used.

In the above embodiment, the ferrite cores are arranged at equal angular intervals, but the present invention is not limited to this. In some cases, the directivity is generated in the magnetic field distribution under the influence of other metal parts. To correct this, the coupling state between the ferrite core and the heating coil 11 is changed to approach the non-directional distribution to reduce the leakage magnetic field. It may be reduced.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to FIG. In FIG. 6, a predetermined distance is provided below the heating coil 14 whose planar shape is elliptical.
Ten ferrite cores 15a to 15j of the same shape are adhered. The difference from the second embodiment is that the intervals between the ferrite cores 15a to 15j and the heating coil are all the same, and that the ferrite cores 15a to 15j are different.
Are not equal to each other (angular spacing)
That is, the distance between the ferrite cores 15a to 15j and the inner peripheral edge of the heating coil 14 is changed depending on the direction.

With the above configuration, the heating coil 14 having an elliptical shape is used.
Ferrite cores 15a, 15 provided in the minor axis direction of
e, 15f, and 15j are arranged on the innermost side (in the center direction of the heating coil 14), and the ferrite cores 15c and 15h provided in the major axis direction of the heating coil 14 are arranged on the outermost side. The spread of the magnetic field distribution in the major axis direction of the coil 14 can be suppressed to reduce the directivity. Further, the ferrite cores 15e and 15f
By making the angle between the ferrite cores 15j and 15a larger than the angle between other adjacent ferrite cores, the directivity of the magnetic field distribution can be reduced and the leakage magnetic field strength can be reduced. It is.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. In FIG. 7, the heating coil 1
6, ferrite cores 17a to 17d are arranged at a certain distance from the lower surface of the heating coil 16.
The difference from the second embodiment is that the relative positional relationship between the ferrite core and the heating coil 11 is the same for all ferrite cores, that is, the distance between the lower surface of the heating coil 16 and the upper surface of the ferrite core is all And that the ferrite cores 17b and 17d are larger in shape than the other ferrite cores (the thickness is the same and the width is about twice as large).

Since the heating coil 16 has a non-circular shape according to the above configuration, directivity is generated in the horizontal distribution of the magnetic field generated from the heating coil 16, and when viewed from the center of the heating coil 16, the magnetic field in the major-axis direction is other than that. Is stronger than the direction of
The cross-sectional area of the ferrite cores 17b, 17d provided in the major axis direction is the same as that of the ferrite cores 17a, 17 arranged in the minor axis direction.
Since the cross-sectional area of the ferrite core is twice as large as that of the ferrite core, the magnetic flux accumulation effect of the entire ferrite core is greater in the major axis direction than in the minor axis direction. Thereby, the directivity of the magnetic field distribution due to the shape of the heating coil 16 is reduced.

In the above embodiment, the cross-sectional area was changed by changing the width of the ferrite core having a substantially rectangular parallelepiped shape, thereby reducing the directivity of the magnetic field distribution and reducing the leakage magnetic flux. It is also possible to obtain a similar effect by changing the directivity of the magnetic field distribution.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 8, the heating coil 18 is wound into a flat plate having a substantially elliptical planar shape, and eight ferrite cores 19 a to 19 h having the same shape are spaced apart from the lower surface of the heating coil 18 by a certain distance. It is provided radially from the center. Ferrite core 19a
19h is determined at an angle to each other so that the distribution density in the major axis direction is increased.

Further, about 1 mm around the heating coil 18
Is provided with a shield ring 20 formed by punching an aluminum plate having a thickness of 1 mm into a ring shape having a substantially constant width over the periphery. The distance between the inner edge of the shield ring 20 and the outer edge of the heating coil 18 is constant.

With the above configuration, a current is induced in the shield ring 20 by the magnetic flux generated from the heating coil 18, and this current cancels out the magnetic field of the heating coil 18 outside the shield ring 20 and leaks from the heating coil 18 to the surroundings. The magnetic field can be reduced. Further, since the distance between the inner edge of the shield ring 20 and the outer edge of the heating coil 18 is constant and the width of the shield ring 20 is substantially the same around the circumference of the heating coil 18, the magnetic field distribution of the heating coil 18 alone and the shield ring 20 are provided. When the leakage magnetic field is reduced by this, the horizontal magnetic field distribution becomes substantially similar and elliptical.

Further, eight ferrite cores 1 having the same shape
9a to 19h are provided radially from the center of the heating coil 18 at a certain distance from the lower surface of the heating coil 18, and the angles formed by the ferrite cores 19a to 19h are mutually formed so that the distribution density in the major axis direction increases. So
By providing the shield ring 20, the directivity of the reduced magnetic field distribution is reduced to approach non-directionality, and the leakage intensity of the magnetic field in a specific direction can be further reduced.

As described above, according to the present embodiment, the shield ring 20 which is continuously provided near the outer periphery of the heating coil 18 having an elliptical planar shape and generates an induction current by the magnetic flux generated by the heating coil 18 is provided. In addition, by increasing the distribution density of the ferrite core in the major axis direction, the leakage magnetic field generated from the heating coil 18 can be more effectively suppressed.

In the fifth embodiment, the distribution density of the ferrite core is varied depending on the direction in order to make the magnetic field distribution closer to non-directional. However, the magnetic coupling between the ferrite core and the heating coil is varied in a specific direction. Alternatively, the shape of the ferrite core may be changed in a specific direction.

In the fifth embodiment, the shield ring 2
Although the width of 0 is constant and the inner edge shape of the shield ring 20 and the outer edge shape of the heating coil 18 are similar, the invention is not limited to this. That is, even when notches are provided at the inner edge of the shield ring 20 or the width of the shield ring 33 is not constant, or when the shape of the inner or outer circumference of the shield ring 33 is not made similar to the shape of the heating coil 11, By changing the shape and arrangement of the ferrite core, it is possible to obtain the effect of relaxing the directivity and reducing the leakage magnetic field. Also, the directivity can be changed by partially changing the distance between the shield ring 20 and the outer peripheral edge of the heating coil 18.

The shield ring 20 is connected to the heating coil 1.
It suffices if it is provided so as to be connected around the periphery of 1, and it may be configured by joining a conductive metal member such as aluminum with a screw or the like.

[0053]

According to the first aspect of the present invention, a non-circular heating coil in which the distance from the center to the outer peripheral edge is not constant in a planar projection shape and a non-circular heating coil on the side opposite to the side where the load is located are provided. A plurality of magnetic members are provided around the center of the non-circular heating coil and arranged substantially in the direction of the center from near the outer periphery of the non-circular heating coil, according to the directivity of the magnetic field distribution of the non-circular heating coil. Since the distribution of the magnetic material is changed, the magnetic field distribution of the non-circular heating coil is a directivity reducing means that approaches non-directionality, so that it is possible to approach a nearly isotropic direction in which the magnetic field intensity does not greatly change depending on the direction,
It can suppress the magnetic field from becoming strong in a specific direction of the induction heating cooker, and can have a simple configuration when assembling, oscillating waveforms of frequency converters such as inverters and cooling inside equipment. It is possible to provide an induction heating cooker having a non-circular heating coil that has a small effect on the effect, is inexpensive, small, and has little leakage magnetic field.

According to the second aspect of the present invention, the distance or the angle between two or more sets of two adjacent magnetic materials among the plurality of magnetic materials is changed by changing the distance between the other two magnetic materials or the distance between the two adjacent magnetic materials. The directivity of the magnetic field distribution due to the non-circular heating coil is provided by means of a non-circular heating coil that is smaller than the angle formed. An object of the present invention is to provide an induction heating cooker that can efficiently suppress an increase in a magnetic field in a specific direction, is inexpensive, small, and has a small magnetic field leaking from the heating coil to the periphery of the device.

According to the third aspect of the present invention, the distribution density of the magnetic material is changed according to the distance from the center to the outer periphery of the non-circular heating coil, and the directivity of the magnetic field distribution generated from the non-circular heating coil is changed. Since the mitigation means is used, the directivity of the magnetic field distribution caused by the shape of the non-circular heating coil can be reduced to approach non-directionality, and the increase in the magnetic field in a specific direction can be suppressed easily and efficiently. It is possible to provide an induction heating cooker which is inexpensive, small, and has a small magnetic field leaking from the heating coil to the periphery of the device.

According to the fourth aspect of the present invention, the distance between one or more specific magnetic substances of the plurality of magnetic substances and the non-circular heating coil is set to be larger than the distance between the other magnetic substances and the non-circular heating coil. By making the configuration smaller, it is possible to suppress the magnetic field leaking from the induction heating cooker to the surroundings, so that the shield member can be omitted or reduced in the adjacent space around the heating coil, so that the equipment can be reduced. It is possible to reduce the size at low cost.

According to the fifth aspect of the present invention, the position of one or more specific magnetic materials among the plurality of magnetic materials is set to be outside or inside the non-circular heating coil in comparison with the positions of the other magnetic materials. Since the magnetic field leaking from the induction heating cooker having the non-circular heating coil to the surroundings can be suppressed by disposing the induction heating cooker having the non-circular heating coil, the induction heating cooking having the small, inexpensive, and non-circular heating coil with little leakage magnetic field can be suppressed. It is possible to provide a vessel.

According to the sixth aspect of the invention, the heating coil is located near the heating coil on the side opposite to the side where the load is located, and is provided around the substantially center of the non-circular heating coil from the vicinity of the outer periphery of the heating coil to the substantially center. The shape of one or more magnetic materials among the plurality of magnetic materials arranged in a different manner from the shape of other magnetic materials,
By using the directivity reducing means of the magnetic field distribution generated from the non-circular heating coil, it is possible to suppress the leakage magnetic field of the non-circular heating coil without complicating the configuration near the non-heating coil. It is possible to provide an induction heating cooker having a non-circular heating coil that is inexpensive, small, and has little leakage magnetic field, with little influence on the oscillation waveform of a frequency conversion device such as an inverter and the cooling effect in the device.

According to the present invention, the directivity of the magnetic field distribution caused by the distance from the center to the outer periphery of the non-circular heating coil is reduced by changing the length or the cross-sectional area of the magnetic material. Therefore, the leakage magnetic field of the non-circular heating coil can be suppressed without complicating the configuration in the vicinity of the non-heating coil, and can be easily realized.
It is possible to provide an induction heating cooker having a non-circular heating coil that is inexpensive, small, and has little leakage magnetic field, with little influence on the oscillation waveform of a frequency conversion device such as an inverter and the cooling effect in the device.

According to the eighth aspect of the present invention, a conductive member for magnetic shield, which is continuously provided near the outer periphery of the non-circular heating coil and generates an induced current by a magnetic flux generated by the non-circular heating coil, and a non-circular heating coil The distribution density of the magnetic body is increased in a specific direction when viewed from the approximate center of the other direction, or the relative positional relationship between the magnetic body and the non-circular heating coil is changed, or the shape of the magnetic body is changed. By making it different, the directivity of the magnetic field distribution by the heating coil and the conductive member for magnetic shielding is made closer to non-directional, the effect of reducing the leakage magnetic field of the conductive member for magnetic shield is made more effective, It is possible to provide an induction heating cooker with a small magnetic field leaking to the cooker.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the induction heating cooker.

FIG. 3 is a view showing the directivity of a magnetic field distribution of the induction heating cooker.

FIG. 4 is a plan view of a main part of an induction heating cooker according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a main part of the induction heating cooker.

FIG. 6 is a plan view of a main part of an induction heating cooker according to a third embodiment of the present invention.

FIG. 7 is a plan view of a main part of an induction heating cooker according to a fourth embodiment of the present invention.

FIG. 8 is a plan view of a main part of an induction heating cooker according to a fifth embodiment of the present invention.

FIG. 9A is a plan view of a main part of a conventional induction heating cooker, and FIG. 9B is a cross-sectional view of the main part.

FIG. 10 is a view showing the directivity of a magnetic field distribution of the induction heating cooker.

[Explanation of symbols]

 6 Non-circular heating coil 8a to 8d Ferrite core (magnetic material) 10 Load 11 Non-circular heating coil 13a to 13d Ferrite core (magnetic material) 14 Non-circular heating coil 15a to 15j Ferrite core (magnetic material) 16 Non-circular heating coil 17a To 17h Ferrite core (magnetic material) 18 Non-circular heating coil 19a to 19h Ferrite core (magnetic material) 20 Shield ring (conductive member for magnetic shield)

Continuation of the front page (72) Inventor Yuji Fujii 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] A non-circular heating coil arranged opposite to a load and having a distance from a center to an outer peripheral edge in a planar projection shape that is not substantially constant; a frequency converter for supplying a high-frequency current to the non-circular heating coil; A plurality of magnetic bodies disposed on a side opposite to a load and arranged in a substantially central direction from the vicinity of the outer periphery of the non-circular heating coil while providing a space around the center of the non-circular heating coil; Is an induction heating cooker in which the distribution of the magnetic field of the non-circular heating coil is changed so as to approach non-directionality. 2. The induction heating cooker according to claim 1, wherein the plurality of magnetic bodies have a distance or an angle between one or more adjacent magnetic bodies smaller than a distance or an angle between other adjacent magnetic bodies. . 3. The induction heating cooker according to claim 1, wherein the arrangement of the plurality of magnetic bodies is changed according to the distance from the center to the outer periphery of the non-circular heating coil. 4. The induction heating cooker according to claim 1, wherein the plurality of magnetic bodies have a relative position between at least one magnetic body and the non-circular heating coil smaller than other relative positions. 5. The magnetic body according to claim 1, wherein the plurality of magnetic bodies are configured such that a distance of at least one magnetic body from the inner peripheral edge of the non-circular heating coil is shifted outward or inward relative to other magnetic bodies. Induction heating cooker. 6. A non-circular heating coil which is disposed opposite to a load and whose projected shape on a plane is not a circle having a substantially constant radius, wherein the shape of at least one of the plurality of magnetic materials is changed to the shape of another magnetic material. 2. The induction heating cooker according to claim 1, wherein the induction heating cooker is different. 7. The induction heating cooker according to claim 1, wherein the plurality of magnetic materials have a length or a cross-sectional area of at least one magnetic material different from that of another magnetic material. 8. A magnetic shield conductive member, which is provided in the vicinity of the outer periphery of the non-circular heating coil and generates an induced current by a magnetic flux generated by the non-circular heating coil. Item 14. The induction heating cooker according to Item 5.