JPH0917564A - Induction heating cooker - Google Patents

Abstract

PURPOSE: To avoid a magnetic field, generated from a heating coil, by n inexpensive constitution, by forming a differential angle between three sets of ferrite cores adjacent to each other smaller than a differential angle between the other ferrite cores adjacent to each other. CONSTITUTION: When a high frequency current is supplied to a heating coil 11 of an induction heating cooker from an inverter constituted on a printed wiring board 18, a magnetic field is generated from the coil 11, to cross this magnetic field with an iron-made pan mounted on a top plate 17, to generate an eddy current in the pan, so as to heat the pan by Joule's heat. Of nine bar- shaped ferrite cores having almost a similar shape and arranged with a space apart in the center periphery of the coil 11 in the vicinity of the heating coil in an opposite side to a side of positioning the load pan, that is, in the vicinity under the coil 11, an angle formed by three sets of the two ferrite cores 15f, 15g and 15g, 15h and 15i adjacent to each other is formed smaller than the angle formed by six sets of combination of the other cores 15a, 15b to 15e, 15f adjacent to each other, to increase distribution density between the cores 15f, 15I as viewed from the center of the heating coil, and spreading a magnetic flux can be contracted.

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.

A conventional induction heating cooker is shown below in FIG.
0 will be described. FIG. 10A is a plan view showing the configuration of a heating coil of a conventional induction heating cooker.
(B) is sectional drawing at the time of incorporating the heating coil in the housing of an induction heating cooker. In FIG. 10A or FIG. 10B, the heating coil 1 wound in a disk shape is placed on the heating coil holding base 2, and the heating coil 1 is placed between the coil holder 3 and the heating coil holding base 2. A coil holder 3 is fixed to the heating coil holding base 2 by sandwiching the outer peripheral portion, and a shield ring 4 configured in a donut shape with a conductive material such as aluminum is provided around the heating coil 1. Here, a substantially constant distance is provided between the inner peripheral edge of the shield ring 4 and the outer peripheral edge of the heating coil 1.

On the lower surface of the heating coil holding base 2, eight substantially rectangular parallelepiped rod-shaped ferrite cores 5a to 5 are formed.
h is from the vicinity of the outer circumference of the heating coil 1
Are provided over the center direction of the ferrite core, and the intervals (angles) between the ferrite cores are substantially equal intervals (equal angles), that is, the angle between adjacent ferrite cores is about 45 degrees. Also, ferrite cores 5a-5
The distance between the upper surface of h and the lower surface of the heating coil 1 is substantially equal, and the ferrite cores 5a to 5h are located from the center of the heating coil.
Are bonded so that the distances to the inner ends of the are substantially equal.

The heating coil holding base 2 is fixed to the upper part of a column provided on the bottom surface of the housing 6, and the heating coil 1 is located below the top plate 7 on which the load pan is placed. In addition, below the ferrite cores 5a to 5h, electrical components such as a switching semiconductor 9 that constitutes an inverter that supplies a high-frequency current to the heating coil 1, cooling fins 10 made of aluminum for cooling the switching semiconductor 9, and a control unit. A printed wiring board 8 on which circuit components and the like are mounted is fixed to the housing 6.

In the above structure, when a high-frequency current is supplied to the heating coil 1 from the inverter, a magnetic field is generated from the heating coil 1, magnetic flux is linked to the load pan on the top plate 7, and an induced current is generated in the load pan. Heat the load pan with heat. A magnetic field is also generated below the heating coil 1, but since the ferrite cores 5a to 5h are arranged,
The lower magnetic flux concentrates on the ferrite cores 5a to 5h and prevents the magnetic flux from spreading downward.

When a high frequency current is supplied to the heating coil 1, a high frequency current is induced in the shield ring 4 by the magnetic field generated by the heating coil 1. The magnetic field generated by the high-frequency current induced in the shield ring 4 strengthens the magnetic field generated by the heating coil 1 inside the shield ring 4, and becomes the magnetic field opposite to the magnetic field generated by the heating coil 1 outside the shield ring 4, thereby heating the shield ring 4. The magnetic field leaking from the coil 1 to the surroundings is reduced.

[0008]

In such a conventional induction heating cooker, the magnetic flux generated by the heating coil 1 interlinks with the aluminum cooling fins 10 to generate an induced current in the cooling fins 10. The anti-magnetic flux generated by the induced current is
There is a problem that it is superimposed on the magnetic flux generated by the heating coil 1 and affects the distribution of the magnetic field leaking around the heating coil 1 to increase the leakage magnetic field in a specific direction.

The heating coil 1 is wound in a substantially disc shape,
The horizontal distribution of the magnetic field generated therefrom has a shape similar to the outer peripheral shape of the heating coil 1, that is, a substantially circular shape when the points of the uniform magnetic field are plotted and connected by a line, and the horizontal distance from the center of the heating coil 1 is the same. At a point, there is an omnidirectional magnetic field distribution in which the magnetic field intensities are almost equal no matter which direction the magnetic field is measured from the center of the heating coil 1.

The induction heating cooker has a frequency conversion device such as an inverter and requires a cooling fin 10 for cooling its switching element. The cooling fin 10 is made of a conductive metal such as aluminum, and has a complicated shape with an uneven shape in order to increase the shape and the surface area for the purpose of enhancing the cooling capacity. In particular, in order to reduce the thickness and size of the induction heating cooker, the cooling fin 10
When the heating coil 1 is arranged close to the lower part of the heating coil 1, the amount of magnetic flux generated by the heating coil 1 interlinking with the cooling fins 10 increases. There was a problem that the horizontal distribution of the magnetic field, which should be directional, is changed to one having directivity due to the influence, and a specific leakage magnetic field increases when viewed from the center of the heating coil 1.

The effect of reducing the leakage magnetic field around the equipment of the shield ring 4 is to bring the inner edge of the shield ring 4 as close as possible to the outer periphery of the heating coil 1 and increase the width of the shield ring 4 to increase the surface area and the induced current. It is better to increase the flowing area of.

Since there are parts such as the coil holder 3 and fixing screws near the outer periphery of the heating coil 1, the inner peripheral edge of the shield ring 4 is set to the outer peripheral edge of the heating coil 1.
In order to bring them closer than shown in (a), it is necessary to cut out the inner peripheral edge of the shield ring 4 in the vicinity thereof so that the inner peripheral edge of the shield ring 4 does not come into contact with the coil holder 3 or a fixing screw. .

When a part of the inner edge of the shield ring 4 is cut out, the distance between the outer peripheral edge of the heating coil 1 and the inner peripheral edge of the shield ring 4 in the cutout portion becomes larger than the distance between the two except the cutout portion. At the cutout portion, the similarity between the outer peripheral edge shape of the heating coil 1 and the inner peripheral shape of the shield ring 4 is broken, and the horizontal distribution of the magnetic field generated by the current of the heating coil 1 and the current induced in the shield ring 4 are The similarity of the horizontal magnetic field distribution of the generated magnetic field is lost.

Since the total horizontal magnetic field distribution is a superposition of the magnetic field distribution generated by the heating coil 1 and the demagnetizing field distribution generated by the shield ring 4, as viewed from the center of the heating coil 1, the cutout direction or 180 degrees thereof. The magnetic field in the opposite direction becomes larger than the other directions, and the directivity is generated in the distribution of the magnetic field generated from the equipment, the leakage magnetic field strength becomes large in a specific direction, and the leakage magnetic field reduction effect of the shield ring 4 is sufficiently exerted. There was a problem that it could not be done.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a low-cost, small-sized, thin induction heating cooker which suppresses the leakage of the magnetic field generated from the heating coil to the surroundings. To do.

[0016]

In order to achieve the above object, the first means of the present invention is to provide a heating coil arranged near the load so as to face the load, and to supply a high frequency current to the heating coil. And a frequency converter that is located near the heating coil on the side opposite to the side where the load is located, with a space provided around the center of the heating coil, and arranged in the approximate center direction from the vicinity of the outer periphery of the heating coil. A plurality of magnetic bodies, the angle formed by two or more magnetic bodies adjacent to each other among the plurality of magnetic bodies is smaller than the angle formed by the other two magnetic bodies adjacent to each other, and from the center of the heating coil. A directivity easing means for the magnetic field distribution generated from the heating coil, which increases the distribution density of the magnetic material in a specific direction when viewed, is provided.

The second means has the same structure as the first means, and a plurality of magnetic bodies of the same shape are provided with a substantially uniform angular difference around the substantially center of the heating coil along the heating coil. The distribution density of the magnetic material is provided in the vicinity of the direction in which the magnetic field leaking from the heating coil is the strongest when viewed from substantially the center of the heating coil. It should be larger than the direction.

The third means is a heating coil arranged near the load so as to face the load, a frequency converter for supplying a high-frequency current to the heating coil, and a side opposite to the side where the load is located. One or more of the plurality of magnetic bodies, the plurality of magnetic bodies being located in the vicinity of the heating coil on one side and provided in the center direction from the vicinity of the outer periphery of the heating coil at intervals around the center of the heating coil. The relative positional relationship between the magnetic body and the heating coil is made different from the relative positional relationship between the other magnetic body and the heating coil to provide directivity relaxing means for the magnetic field distribution generated from the heating coil. is there.

A fourth means is the constitution of claim 3, wherein the distance between one or more magnetic bodies of the plurality of magnetic bodies and the heating coil is the same as that of the other magnetic bodies and the heating coil. The configuration is such that it is smaller than the distance from the coil.

The fifth means has the same structure as the fourth means, and a plurality of magnetic bodies of the same shape are provided with a substantially uniform angular difference around the substantially center of the heating coil along the heating coil. The magnetic body and the heating coil are provided and distributed to be incorporated in a housing, the frequency conversion device is operated, and the magnetic field leaking from the heating coil is in the vicinity of a direction in which the magnetic field is the strongest when viewed from substantially the center of the heating coil. Is smaller than the distance between the magnetic body and the heating coil in the other direction.

The sixth means is the same as the third means, and the position of one or more magnetic bodies of the plurality of magnetic bodies is higher than that of the other magnetic bodies. The coil is displaced to the outside or inside in the radial direction of the coil.

The seventh means is the structure of the means according to claim 6, wherein a plurality of magnetic bodies having the same shape are provided around the substantially center of the heating coil so as to have a substantially uniform angular difference along the heating coil. Are installed and distributed in a housing, the frequency converter is operated, and the position of the magnetic body is changed to another position in the vicinity of the direction in which the magnetic field leaking from the heating coil is the strongest when viewed from the substantial center of the heating coil. The heating coil is arranged so as to protrude in the radial direction relative to the position of the magnetic body.

The eighth means is a heating coil arranged near the load so as to face the load, a frequency converter for supplying a high frequency current to the heating coil, and a side opposite to the side where the load is located. A plurality of magnetic bodies located near the heating coil on one side and arranged around the center of the heating coil at intervals from the vicinity of the outer periphery of the heating coil, and at least one of the plurality of magnetic bodies The directivity alleviating means for the magnetic field distribution generated from the heating coil, which is formed by making the shape of the magnetic body different from the shape of other magnetic bodies, is provided.

The ninth means is the same as the eighth means, and a plurality of magnetic members having the same shape are provided around the center of the heating coil with a substantially uniform angular difference along the heating coil. Are distributed and incorporated into a housing to operate the frequency conversion device, and the length or cross-sectional area of the magnetic body is adjusted in the vicinity of the direction in which the magnetic field leaking from the heating coil is the strongest when viewed from the substantial center of the heating coil. It is made larger than other magnetic materials.

The tenth means has the first, third, or eighth structure, and the plurality of magnetic bodies are the power semiconductors of the frequency converter when viewed from substantially the center of the heating coil. Is the distribution density higher in the vicinity of the direction where the cooling fins are located than in other directions, or
Alternatively, the distance between the magnetic body and the heating coil is reduced, or the position of the magnetic body is arranged so as to project in the radial direction of the heating coil, or the length or cross-sectional area of the magnetic body is increased. is there.

The eleventh means holds a heating coil arranged near the load so as to face the load, a frequency converter for supplying a high-frequency current to the heating coil, the heating coil, and a powder. The heating coil holding part formed of a mixed material of the magnetic body and the insulating resin material and the magnetic body provided near the heating coil holding part are provided, and the magnetic body is biased in a specific direction when viewed from the center of the heating coil. Is provided to reduce the directivity of the magnetic field distribution generated from the heating coil.

The twelfth means is a heating coil arranged near the load so as to face the load, a frequency converter for supplying a high-frequency current to the heating coil, and a heating coil for holding the heating coil. A holding portion and a plurality of magnetic bodies provided in the vicinity of the heating coil on the side opposite to the side where the load is located, and a part of the plurality of magnetic bodies is formed integrally with the heating coil holding portion, A magnetic material other than the above is provided with means for reducing the directivity of the magnetic field distribution generated from the heating coil, which is fixed to the heating coil, the heating coil holding portion or other parts by a fixing means other than integral molding. .

[0028] A thirteenth means has the twelfth structure, wherein the plurality of magnetic bodies are rod-shaped with substantially the same shape, and the magnetic bodies integrally formed with the heating coil holding portion are adjacent to each other. The angle formed with the other integrally formed magnetic body is substantially equal to or is an integer multiple of the minimum value of the angle formed between the other integrally formed magnetic body adjacent to the integrally formed magnetic body, In addition, one or more magnetic bodies are fixed between the integrally formed magnetic bodies by a fixing means other than integral molding with the heating coil holding portion.

The fourteenth means has the structure of the first means, the third means, or the eighth means, and is continuously provided in the vicinity of the outer circumference of the heating coil, and the magnetic flux generated by the heating coil is generated. A magnetic shield conductive member for generating an induced current is provided.

[0030]

According to the first means for solving the problems described above, when a high frequency current is supplied to the heating coil from the frequency converter, magnetic flux is generated on both sides of the surface of the winding of the heating coil (hereinafter referred to as the heating coil surface). A load placed facing the one side is heated. 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 the effect of reducing the magnetic field strength in the vicinity of the direction in which the magnetic body is arranged when viewed from the center of the heating coil, and one or more sets of adjacent magnetic bodies are adjacent to each other. Make the angle between the two magnetic bodies smaller than the angle between the other two adjacent magnetic bodies, and increase the distribution density of the magnetic body in a specific direction when viewed from the center of the heating coil. Therefore, the magnetic flux focused by the magnetic substance increases in that direction, and the suppression level of the magnetic field strength generated from the heating coil near that direction is made higher than in other directions. The directivity of the magnetic flux distribution can be changed by devising the arrangement of a plurality of magnetic bodies as described above.

On the other hand, the induction heating cooker has a structure in which a heating coil is housed inside a chassis made of iron or aluminum, and below or in the vicinity thereof is made of aluminum used for cooling a power semiconductor which is a component of a frequency conversion device. In many cases, metal parts such as heat dissipation fins are placed, and as a result of the magnetic field generated from the heating coil interlinking with the chassis and heat dissipation fins,
The magnetic field generated by the heating coil is affected, the magnetic field level becomes strong in a specific direction when viewed from the center of the heating coil, and the magnetic field distribution becomes directional.

This magnetic field distribution with directivity has a large change in magnetic field strength depending on the direction by providing the directivity relaxing means for the magnetic field distribution generated from the above-mentioned heating coil in which a plurality of magnetic bodies are arranged in a specific arrangement. It is possible to make them substantially isotropic, and it is possible to prevent the magnetic field from becoming strong in a specific direction of the induction heating cooker.

According to the second means for solving the problems, when the plurality of magnetic bodies having the same shape are distributed around the substantially center of the heating coil along the heating coil with a substantially uniform angular difference, the frequency converter is operated. If there is no influence of surrounding parts, the distribution of the magnetic field generated from the heating coil will be substantially proportional to the shape of the heating coil. When the heating coil and the magnetic body in this state are incorporated into the main body for operation, the magnetic flux distribution has a directivity in which the magnetic field strength is stronger in a specific direction than in other directions due to the influence of other metal parts inside the main body. Will have. Therefore, by measuring this distribution, the direction in which the component other than the heating coil causes the heating coil to have directivity can be specified.

The direction in which the directivity specified as described above occurs, that is, the direction in which the magnetic field leaking from the heating coil under the influence of other metal parts becomes the strongest when viewed from the substantial center of the heating coil, Since the distribution density is made larger than the other directions to make it substantially coincide with the direction with a high magnetic flux focusing level, the directionality of the magnetic field distribution is offset by the directionality of the focusing effect of the magnetic substance, and the correction is made to be approximately isotropic. The leakage magnetic field can be suppressed.

According to the third means for solving the problems, the relative positional relationship between one or more magnetic bodies among the plurality of magnetic bodies and the heating coil is made different from the relative positional relationship between the other magnetic bodies and the heating coil. As a directivity relaxing means for the magnetic field distribution generated from the heating coil, the magnetic coupling state between the magnetic body in a specific direction and the heating coil can be made different from the magnetic coupling state between the magnetic body in another direction and the heating coil. . When the magnetic coupling state between the heating coil and the magnetic body is different, the magnetic flux focusing effect of the magnetic body is different, so that the direction in which the magnetic flux focusing effect is greater than the other directions can be generated. By making the direction and the direction in which the directivity becomes stronger due to the influence of the parts of the equipment approximately match or close to each other, it is possible to correct the directivity of the magnetic field distribution due to other parts of the equipment and make it close to non-directional. Can be suppressed.

According to the fourth means for solving the problems, heating is performed by setting the distance between one or more specific magnetic bodies of the plurality of magnetic bodies and the heating coil smaller than the spacing between the other magnetic bodies and the heating coil. Since the relative positional relationship with the coil is different, the magnetic coupling between the magnetic body and the heating coil in that direction is increased, the focusing effect of the magnetic flux generated from the heating coil is increased, and the magnetic field suppression effect in that direction is increased. Can be made larger than in other directions. The direction in which the directivity of the heating coil becomes stronger due to the influence of the metal parts inside the main body and the direction in which the above-mentioned magnetic flux converging effect becomes greater are approximately matched or close to each other, so that the directivity of the magnetic field distribution is relaxed and becomes closer to isotropic. You can

By the fifth means for solving the problems, when a plurality of magnetic bodies having the same shape are distributed around the substantially center of the heating coil at equal angles along the heating coil, the frequency converter is operated. If there is no influence of the parts, the distribution of the magnetic field generated from the heating coil will be a distribution substantially proportional to the shape of the heating coil. When the heating coil and magnetic material in this state are incorporated into the main body to operate, the magnetic flux distribution is affected by other metal parts inside the main body, and the magnetic field strength is higher than the other directions in a specific direction when viewed from the center of the heating coil. It has a strong directivity. Therefore, by measuring this magnetic field distribution, the direction in which the components other than the heating coil cause the heating coil to have directivity can be specified.

The direction in which the directivity specified as described above occurs, that is, the direction in which the magnetic field leaking from the heating coil under the influence of other metal parts is the strongest when viewed from the substantial center of the heating coil, and the magnetic body Since the direction in which the magnetic flux suppression level is increased by setting the distance between the heating coil and the magnetic material near the other direction to be smaller than the distance between the magnetic material and the heating coil is approximately the same, the magnetic field suppression effect of the magnetic material determined by the arrangement of the magnetic materials A directivity of the magnitude that can offset the directivity of the magnetic field distribution caused by the influence of other parts of the device to make it nearly isotropic and suppress the spread of the leakage magnetic field in a specific direction. Is.

By the sixth means for solving the problems, the position of one or more specific magnetic members of the plurality of magnetic members is compared with the position of the other magnetic members so that the heating coil is radially outside or inside. To change the relative positional relationship with the heating coil to change the magnetic coupling state between the magnetic body and the heating coil in the other direction in a specific direction, and to direct the focusing effect of the magnetic field by the arrangement of the magnetic body. The directionality of the magnetic field distribution can be mitigated by utilizing the directionality of the magnetic field distribution in the specific direction due to the influence of the metal parts inside the main body, and the magnetic field distribution can be approximated to the isotropic direction.

According to the seventh means for solving the problems, when a plurality of magnetic bodies having the same shape are distributed around the substantially center of the heating coil at substantially equal angles along the heating coil, the frequency converter is operated. If there is no influence of other components, the distribution of the magnetic field generated from the heating coil will be a distribution substantially proportional to the shape of the heating coil. When the heating coil and the magnetic body in this state are incorporated into the main body and operated, the magnetic field distribution has a directivity in which the magnetic field strength is stronger than the other directions in a specific direction under the influence of other metal parts inside the main body. Will be things. Therefore, by measuring this distribution, the direction in which the component other than the heating coil causes the heating coil to have directivity can be specified.

The direction in which the directivity specified as described above occurs, that is, the direction in which the magnetic field leaking from the heating coil under the influence of other metal parts becomes the strongest as viewed from the substantial center of the heating coil, Compared to the position of the magnetic substance in the other direction, the position is arranged so as to project outward in the radial direction of the heating coil, and the direction in which the focusing effect of the magnetic flux generated around the outside of the heating coil is made larger than in other directions. The magnetic field distribution directivity due to the influence of the metal parts inside the main body is offset by the directivity of the magnetic flux focusing effect of the magnetic substance, and the magnetic field distribution is corrected to be substantially isotropic and the leakage magnetic field is suppressed. be able to.

According to the eighth means for solving the problems, the shape of one or more specific magnetic bodies among the plurality of magnetic bodies is made different from the shape of the other magnetic bodies, and the directivity of the magnetic field distribution generated from the heating coil is set. Since the changing means is used, for example, the shape of the magnetic body in a specific direction when viewed from the center of the heating coil can be increased to enhance the magnetic flux converging effect, and the effect of suppressing the magnetic field strength in that direction can be enhanced more than in other directions. By approximating the direction in which the direction of the magnetic field of the heating coil becomes stronger due to the influence of that direction and the parts of the equipment, or close to it, the directivity of the magnetic field distribution due to other parts of the equipment should be corrected to approach non-directionality. Therefore, the leakage magnetic field can be suppressed.

According to the ninth means for solving the problems, when a plurality of magnetic bodies having the same shape are distributed around the substantially center of the heating coil at substantially equal angles along the heating coil, the magnetic field generated from the heating coil is The distribution has a distribution substantially proportional to the shape of the heating coil. When the heating coil and the magnetic body in this state are incorporated into the main body for operation, the magnetic field distribution described above has a directivity in which the magnetic field strength is stronger in a specific direction than in other directions under the influence of other metal parts inside the main body. Will have. Therefore, by measuring this distribution, the direction in which the component other than the heating coil causes the heating coil to have directivity can be specified.

The direction in which the directivity specified as described above occurs, that is, the direction in which the magnetic field leaking from the heating coil under the influence of other metal parts is the strongest when viewed from the substantial center of the heating coil, The length or cross-sectional area is made larger than that of other magnetic materials so that the effect of focusing the magnetic flux around the outside of the heating coil is made larger than the other directions, and the magnetic flux focusing of the magnetic material as a whole The directivity of the effect cancels the directivity of the magnetic field distribution due to the influence of the metal parts inside the main body, and the magnetic field distribution can be corrected to be substantially isotropic and the leakage magnetic field can be suppressed.

According to the tenth means for solving the problems, the distribution density is made higher in the vicinity of the direction in which the cooling fins of the power semiconductor of the frequency conversion device are located, as compared with the other directions, as viewed from the substantial center of the heating coil. The position of the body is brought closer to the heating coil compared to the position of the magnetic body in another direction, or the position of the magnetic body is set in the radial direction of the heating coil compared to the position of another magnetic body. Since it is arranged so as to project or the length or cross-sectional area of the magnetic body is increased, it is possible to prevent the directivity of the magnetic field distribution of the heating coil from becoming extremely strong in a specific direction due to the influence of the cooling fins. be able to. That is, since the cooling fin has a large loss of power semiconductor, it is necessary to increase the surface area, and since there is a tendency for the cooling fin to have a large number of irregularities and a large shape to enhance the cooling capacity, the magnetic flux of the heating coil is linked to the cooling fin. The magnetic flux distribution may change due to the current induced in the cooling fins, and the magnetic field may become stronger in the direction in which the cooling fins are located when viewed from the center of the heating coil. It is possible to suppress the leakage magnetic field by enhancing the magnetic flux converging effect of (1) above that in other directions so that the directivity of the magnetic field distribution generated around the device becomes closer to isotropic.

According to the eleventh problem-solving means, since the magnetic powder is mixed in the heating coil holding portion, the heating coil holding portion can be provided with an action of reducing the magnetic field leaking to the heating coil holding portion side. In order to produce a mixture of magnetic powder in the heating coil holder, it is necessary to use a mold to perform molding using an integrated molding machine. Considering the amortization cost of the mold or the molding machine usage fee, etc. If not produced in large quantities, the cost will be high. Therefore, if the heating coil holding part mixed with powder of magnetic material is used in common for multiple models to increase the number of production and reduce the production cost, parts other than the heating coil will not be able to distribute the magnetic field of the heating coil. The magnetic field strength of the heating coil is increased in a specific direction, a non-powdered magnetic material may be removed from the heating coil depending on the model. The magnetic field distribution generated from the heating coil can be made non-directional to prevent the expansion of the leakage magnetic field in a specific direction by correcting the distribution by biasing the distribution in a specific direction.

By the twelfth problem solving means, one or more specific magnetic bodies of the plurality of magnetic bodies are integrally formed with the heating coil holding portion, and the other magnetic bodies are the heating coil or the heating coil holding portion. Alternatively, since it is fixed to other parts by fixing means other than integral molding, the heating coil holding part integrally molded with the magnetic body is mass-produced by sharing it with a model of the main body structure or a model with different component arrangement of the frequency conversion device. By changing the presence or absence of a magnetic body fixed by a fixing means other than integral molding, or the position, for each model, the directivity of the magnetic field distribution due to the metal chassis or the metal parts of the frequency conversion device can be reduced. Can be corrected.

By the thirteenth means for solving the problems, a plurality of magnetic bodies are formed into a rod shape having substantially the same shape, are distributed radially from the vicinity of the outer periphery of the heating coil toward the center, and are integrally molded with the heating coil holding portion. The angles that the magnetic bodies make with the adjacent magnetic bodies are all approximately equal, or the angles formed by the integrally molded magnetic bodies and other integrally molded magnetic bodies that are adjacent to each other are approximately integer multiples of the adjacent magnetic bodies. If the angles formed by the integrally molded magnetic bodies are all approximately the same, the magnetic field distribution from the heating coil will be the same as the shape of the heating coil when there is no influence of other parts during operation, and When the angle between them is twice or more, the magnetic field increases in the direction in which the angle formed between the magnetic bodies increases. When this heating coil is incorporated into a device, this distribution is disturbed by the metal parts of the device, resulting in a distribution with a specific directivity, the extent of which depends on the internal configuration of the device and the magnitude of the current flowing through the heating coil.
Some models can be used as they are.

Further, since one or more magnetic bodies are fixed to any one of the integrally formed magnetic bodies by a fixing means other than the one integrally formed with the heating coil holding portion, the magnetic bodies are arranged as described above. The one-piece molded product is used by sharing it with models of different structures, and the difference in the influence of the structure of each model is fixed or fixed by means other than the one-piece molding, such as adhesion or mechanical fixing. Can be corrected with
The manufacturing cost of the heating coil can be reduced. That is, since the integral molding can omit the adhesive and the bonding work, the cost is reduced accordingly, but the molding die cost for the integral molding becomes expensive. However, as the number of manufactured units increases, the depreciation cost per unit decreases. Therefore, if the heating coil holders can be shared by different models, the number of heating coil holders produced can be increased.
It is possible to reduce the number of magnetic bodies to be fixed by gluing or the like to the number necessary to correct the directivity of the magnetic field distribution, and to reduce the cost.

Further, since the minimum value of the angle between the integrally molded magnetic body and the adjacent integrally molded magnetic body is set to be an integral multiple, it is easy to adjust the directivity by the magnetic body not integrally molded. Become. That is, where the angle between the integrally molded magnetic bodies is twice the minimum angle, one magnetic body that is not integrally molded is provided at a place where the magnetic body is divided into two, and the angle is tripled. If two magnetic poles are provided in three places, the magnetic material can be evenly divided around the center of the heating coil, and if it is built into the equipment and operated in that state, the magnetic field will be affected by parts other than the heating coil of the equipment. The direction in which the magnetic field becomes stronger can be specified, and the position of the magnetic body that is not integrally molded may be changed so that the distribution density of the magnetic body becomes higher in that direction, and the magnetic field distribution may be adjusted so as to approach non-directionality.

According to the fourteenth problem solving means, since the magnetic shield conductive member which is continuously provided in the vicinity of the outer periphery of the heating coil and generates the induced current by the magnetic flux generated by the heating coil is provided, the heating coil is generated. Due to the magnetic flux, an anti-magnetic flux flows in the conductive member for magnetic shield, and the anti-magnetic flux cancels the magnetic flux of the heating coil around the equipment to reduce the leakage magnetic field from the equipment. The closer the magnetic shield member is to the outer peripheral portion of the heating coil, the greater the effect of reducing the leakage magnetic field.

However, in the vicinity of the outer periphery of the heating coil, there are a lead wire lead-out portion of the heating coil and a component attached to the heating coil holding portion of the heating coil, and the distance between the outer periphery of the heating coil and the conductive member for magnetic shield is close. It may be difficult to make it constant, and it may be difficult to make the width of the magnetic shield conductive member constant. Even if the distance between the heating coil and the conductive member for magnetic shield is not constant and partially increases or decreases, or the distance between the heating coil and the member for magnetic shield is constant, the width of the conductive member for magnetic shield is constant. If not, the directivity appears remarkably in the magnetic field distribution, and the magnetic field becomes strong in a specific direction. Even in such a case, by changing the shape and arrangement of the magnetic body as described above, the magnetic field distribution having remarkable directivity can be corrected so as to approach the non-directional one, and the magnetic shield member The effect of reducing the leakage magnetic field and the effect of magnetic focusing of the magnetic substance can be synergistically enhanced, and the magnetic field reducing effect can be further enhanced.

[0054]

【Example】

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

As shown in the sectional view of FIG. 1 (a), the heating coil holding base 12 is placed on a support provided on the bottom surface of the resin casing 16 and fixed by screws. The heating coil 11 is placed on the coil holder 12, and a ceramic top plate 17 is arranged above the heating coil 11. The heating coil 11 has its peripheral portion pressed against the heating coil holding base 12 by the coil holder 13 and fixed by screws, and the lead wire of the heating coil 11 is connected to the printed wiring board 18. The printed wiring board 18 is provided on the bottom surface of the housing 16 and is provided with an electric component or a control circuit component thereof necessary for forming an inverter which is a kind of frequency conversion device that generates a high frequency current. Each component is electrically connected by attachment.

The switching transistor 19 is a power semiconductor for generating a high frequency current, and is mounted on a cooling fin 20 made of resin and molded of aluminum.
Since the heat loss during inverter oscillation is large, the cooling fin 2
A cooling fan (not shown) placed in the vicinity of 0 sends air to cool the air. Heating coil holder 12
Nine, rod-shaped ferrite cores 15a to 15i having substantially the same rectangular parallelepiped shape are bonded to the lower surface of the.

FIG. 1 (b) shows a planar positional relationship among the heating coil holder 12, the heating coil 11, the ferrite cores 15a to 15i, and the cooling fins 20. The ferrite cores 15a to 15i are radially arranged around the center of the heating coil 11 from the vicinity of the outer periphery of the heating coil 11 to the center direction, and the angle formed by the center lines of the ferrite cores 15a and 15b is about 45.
The ferrite cores 15b and 15c, the ferrite cores 15c and 15d, the ferrite cores 15d and 15e, the ferrite cores 15e and 15f, and the ferrite cores 15i and 1
Similarly, 5a is arranged so that the angle formed by each center line is about 45 degrees.

On the other hand, the angle formed by the center lines of the ferrite cores 15f and 15g, the ferrite cores 15g and 15h, and the ferrite cores 15h and 15i is fixed at about 30 degrees. The alternate long and short dash line indicates FIG.
As shown in (a), the cooling fins 20 are arranged near the lower part of the heating coil 11.

The operation of the induction heating cooker configured as described above will be described. When a high-frequency current is supplied to the heating coil 11 from an inverter configured on the printed wiring board 18, a magnetic field is generated from the heating coil 11 and the magnetic field is interlinked with, for example, an iron pot placed on the top plate 17. Then, an eddy current is generated in the pot and the pot heats up due to Joule heat.

As indicated by the solid line A in FIG. 2, the heating coil 11
The magnetic lines of force generated from the pan 2 are above the heating coil 11.
It is linked to the bottom of No. 4 and passes through the ferrite core 15 below the heating coil 11. A loop antenna is used to measure the leakage magnetic field around the equipment, the heating coil 11 and the loop antenna are installed at a height of about 1 m from the ground, and the loop antenna is placed 3 m away from the equipment. Is installed vertically on the ground, and while the equipment is rotating, the fundamental frequency of the inverter 25
The maximum magnetic field strength at kHz is measured as shown in FIG.

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 cross-sectional view of FIG. 1 (a) faces the direction of the loop antenna, that is, the direction of the ferato core 15a of FIG. 1 (b) is set to 0 degree, and the device is set to the center of the heating coil 11. Is the angle rotated clockwise around the center, and the magnetic field strength is plotted by measuring the maximum magnetic field strength that can be measured by rotating the loop antenna.

Further, in FIG. 3, the measurement result of the horizontal magnetic field distribution shown by the solid line A is for the conventional configuration shown in FIGS. 10 (a) and 10 (b), and the ferrite cores 5a to 5h are shown.
Are arranged around the center of the heating coil 1 at equal angular intervals. In this case, the heating coil 1
The magnetic field in the directions of 90 degrees and 270 degrees from the center has a strong directional distribution. On the other hand, the broken line B in FIG.
The measurement result of magnetic field distribution in the structure shown to (a), (b) is shown. In this case, the magnetic field strength hardly changes depending on the direction, and the leakage magnetic field in the directions of 90 degrees and 270 degrees is reduced as compared with the conventional configuration of solid line A in FIG. doing.

When the ferrite core is arranged with a uniform angle difference around the center of the heating coil 1 as shown in FIG. 10A, when the heating coil 1 is installed in the housing, the heating coil 1 As long as there is nothing disturbing the magnetic field distribution of the heating coil 1, the heating coil 1 has a disk shape, and therefore the magnetic field distribution also has a circular shape similar to that shape, and even if the direction of the device is changed around the center of the heating coil 1. Although the magnetic field strength does not change so much and becomes almost omnidirectional, as shown in FIGS. 1 (a) and 1 (b), a large and complex cooling fin 20 made of aluminum, which is a good conductor, is provided near the heating coil 11. Since it exists, the magnetic field of the heating coil 11 interlinks with the cooling fin 20,
An electric current is induced in the cooling fin 20, and the magnetic field distribution changes due to the influence of the anti-magnetic flux.

FIG. 2 shows such a situation. When the cooling fins 20 are not present, the magnetic force lines shown by the broken line B in the figure are distributed, and when the cooling fins 20 are present, the distribution of the magnetic force lines is shown as the solid line A in the figure. It was confirmed by an experiment that the magnetic field distribution has a directional magnetic field distribution in which the magnetic field strength is stronger than the other directions in the directions of 90 degrees and 270 degrees of the device as shown in FIG. There is.

However, in FIG. 1 (b), the ferrite cores 15f and 15g and the ferrite cores 15g and 1g
5h, the angle formed by the center lines of each of the ferrite cores 15h and 15i is narrower than the angle formed by the center lines of the adjacent ferrite cores of the other combinations. The distribution density of the ferrite core between the core 15f and the ferrite core 15i becomes larger than in other directions.

As a result, the magnetic flux converging effect by the ferrite core becomes large in that direction, and the spread of the magnetic force lines is reduced to the same extent as the broken line B in FIG. 2, that is, the spread of the magnetic force lines is reduced to the same extent as when the cooling fin 20 is not present. The horizontal magnetic field distribution also reaches the level shown by the broken line B in FIG. 3, and the horizontal spread of the magnetic field distribution in the directions of 90 degrees and 270 degrees is reduced, resulting in a distribution having almost no directivity. be able to.

As described above, according to this embodiment, a space is provided 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, that is, below the heating coil 11. Of the nine rod-shaped ferrite cores having substantially the same shape, the angle formed by the two adjacent three ferrite cores 15f and 15g, the ferrite cores 15g and 15h, and the ferrite cores 15h and 15i is set to the angle of the other six pairs. A combination of matching ferrite cores, that is, the ferrite cores 15i and 15a and the ferrite core 15a,
15b and 15b, 15c and ferrite core 15
c, 15d and the ferrite cores 15d, 15e and the ferrite cores 15e, 15f are made smaller than each angle, and the magnetic field distribution near the direction of the cooling fin 20 as viewed from the center of the heating coil 11 is made larger than the other directions. The heating coil 11 is installed in the housing 1 by providing directivity relaxing means for the magnetic field distribution generated from the heating coil 11.
6, the horizontal magnetic field distribution of the magnetic field leaking from the heating coil 11 to the surroundings of the device when it is incorporated in the device 6 is made omnidirectional to suppress the leaking magnetic field.

The angle between adjacent ferrite cores is set by arranging ferrite cores of the same shape at equal angular intervals radially around the center of the heating coil and operating them by incorporating them in a housing. When measuring the horizontal magnetic field distribution, the magnetic field leaking from the equipment is seen from the center of the heating coil,
By adjusting the direction of the ferrite core so that the angle made by the ferrite core is smaller than the other directions near the strongest direction, it is possible to approach an omnidirectional magnetic field distribution and easily suppress the leakage magnetic field. You can

Further, even if the total number of ferrite cores is increased with the same angle between the ferrite cores as in the conventional case,
Although the magnetic field distribution from the heating coil is disturbed by the conductive metal parts near the heating coil, directivity is generated, and the leakage magnetic field increases in a specific direction, so the magnetic shield effect is limited.
Since the directivity of the magnetic field distribution can be finely adjusted as the total number of ferrite cores is increased, the total number of ferrite cores may be increased or decreased as necessary.

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, and the angle between specific cores is 0 as in the ferrite cores 29a and 30g in FIG. The distribution density of the magnetic material in a specific direction may be increased by arranging them in parallel, that is, in parallel. 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.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG. FIG. 4A is a cross-sectional view taken along the line AA ′ in the plan view shown in FIG. The difference from the first embodiment is that the total number of ferrite cores is 8,
They are provided around the center of the heating coil 11 radially with an equal angular interval of about 45 degrees with the adjacent ferrite core,
The cooling fin 20 is provided below the heating coil 11.
Two ferrite cores 22g, 2 located near the top of the
The distance between the upper surface of 2h and the lower surface of the heating coil 11 is h1 = 1.
The remaining six ferrite cores 22a, 22b, 2 in mm
2c, 22d, 22e, 22f upper surface and heating coil 11
Since the distance from the lower surface of the coil is h2 = 3 mm, the thickness of the coil holder 23 is partially different in order to secure the distance between the heating coil 11 and the core. Other configurations are the same as those in FIGS. 1A and 1B of the first embodiment.

In the above structure, since the distance between the two ferrite cores 22g and 22h and the heating coil 11 is smaller than the distance between the other ferrite cores and the heating coil 11, the heating coil 11 and the ferrite cores 22g and 22h are separated from each other. The magnetic coupling state with the heating coil 11 is stronger than the magnetic coupling state between the other ferrite cores and the heating coil 11. When the magnetic coupling state between the ferrite core and the heating coil 11 becomes stronger, the number of the heating coils 11 that focus on the ferrite core increases, so that the ferrite cores 22g and 22h in the direction of the heating coil 11 and in the direction 180 degrees opposite thereto can be seen. It is possible to suppress the magnetic flux from spreading in the surrounding horizontal direction.

As described above, according to the present embodiment, in the vicinity of the heating coil 11 on the side opposite to the side where the load pan is located, that is, in the vicinity of the lower side of the heating coil 11, radially uniform angular intervals are provided around the center of the heating coil 11. Of the eight rod-shaped ferrite cores of substantially the same shape arranged with
If the relative positional relationship between g and 22h and the heating coil 11 (distance between them in this case) is different from the relative positional relationship between other ferrite cores and the heating coil 11 (distance between both in this case). By setting (in this case, reducing), the ferrite cores 22g and 22h and the heating coil 11
Magnetic coupling state with other ferrite core and heating coil 1
Since it is stronger than the magnetically coupled state with No. 1, the same effect can be obtained as in Example 1 by narrowing the angle between the ferrite cores in the specific direction and increasing the distribution density of the ferrite cores in the specific direction. be able to. Therefore, the heating coil 11
Due to the influence of the metal parts or the cooling fins 20 provided in the vicinity of the heating coil 11, the directivity generated in the horizontal distribution of the magnetic field around the equipment due to the magnetic field generated by the heating coil 11 can be mitigated to approach the non-directionality. It is possible to prevent the magnetic field in a specific direction as seen from the center of 11 from becoming particularly strong and increasing the leakage magnetic field.

In the second embodiment, the ferrite cores of the same shape were used at equal angles, but the present invention is not limited to this, and even if the ferrite cores of the same shape are not used, the structure of internal parts or Even if the ferrite cores cannot be arranged at equal angular intervals for other reasons, the coupling state between the ferrite core and the heating coil 11 is changed to the magnetic field when the heating coil 11 is incorporated into the housing to operate. By changing according to the directivity of the distribution, it is possible to approach the non-directional distribution and reduce the leakage magnetic field.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to FIG. In FIG. 5, the heating coil 11 is placed on the heating coil holder 25, and eight ferrite cores 24 of the same shape are placed under the heating coil holder 25.
a to 24h are adhered. The difference from the second embodiment is that the intervals between the ferrite cores 24a to 24h and the heating coil are all the same, and that the two cores located near the upper portion of the cooling fin 20 are larger than the ferrite cores 24a to 24f. The ferrite cores 24g and 24h are shifted in the radial direction (outward) by about 10 mm.

With the above structure, the two ferrite cores 24
Since the g and 24h are configured to project outward from other ferrite cores, the ferrite cores 24g and 24h
It has been confirmed by experiments that the horizontal spreading of the magnetic field in the direction of can be suppressed. Therefore, as in the first or second embodiment, even if the cooling fin 20 or the like causes the magnetic field distribution of the heating coil 11 to have directivity and the magnetic field in the direction of the heat sink 20 becomes strong, it is still in that direction. By displacing the positions of the ferrite cores 24g and 24h in the outward direction or by displacing the positions of the other ferrite cores inward (in the direction of the center of the heating coil 11), it is possible to suppress the directivity from becoming strong and to provide omnidirectionality. It is possible to reduce the leakage magnetic field strength by approaching to.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to FIG. In FIG. 6, the heating coil 11 is placed on the heating coil holder 25, and the eight ferrite cores 26 a to 26 h are arranged under the heating coil holder 25.
Is glued. The difference from the third 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 center of the heating coil 11 on the inner end surface of the ferrite cores 26a to 26h. Is almost equal for all ferrite cores, and the two ferrite cores 26g and 26h located near the upper portion of the cooling fin 20 are
Is larger than other ferrite cores (the thickness is the same and the width is about double).

With the above structure, due to the influence of the cooling fins 20 and the metal parts such as the casing, the horizontal distribution of the magnetic field generated from the heating coil 11 has a directivity.
Even if the magnetic field on the side opposite to the direction of the cooling fin 20 by 180 degrees is stronger than the other directions as viewed from the center of the, the shape of the ferrite cores 26g and 26h is larger than that of the other ferrite cores. However, since the magnetic flux converging effect becomes large in this direction, the directivity can be alleviated, and the leakage magnetic field can be prevented from becoming strong in the specific direction.

In this embodiment, the ferrite core 26
The width of g and 26h is made larger than that of other ferrite cores to enhance the magnetic flux converging effect. However, not limited to this, the thickness of the ferrite core is increased to increase the cross-sectional area or length. Good.

(Fifth Embodiment) The fifth embodiment of the present invention will be described below with reference to FIG. The difference from the fourth embodiment is that two rod-shaped ferrite cores 28a, 28b having the same shape are located near the upper portion of the cooling fin 20 on the lower surface of the coil holding table 27 on which the heating coil 11 is placed. That is, the coil holder 27 is made of a material in which ferrite powder is uniformly mixed with resin.

With the above structure, since the ferrite powder, which is a magnetic material, is uniformly mixed in the coil holder 27,
The magnetic field in all directions of 360 degrees around the heating coil 11 can be uniformly reduced, and rod-shaped ferrite cores 28a and 28b are arranged in the direction of the cooling fins 20 when viewed from the center of the heating coil 11 to reduce the magnetic field in that direction. Since the effect is particularly large, when the heating coil 11 is incorporated in the housing and operated, the horizontal distribution of the magnetic field generated from the heating coil 11 is affected by the influence of the cooling fins 20 and the metal parts such as the housing. Directivity is created, and when viewed from the center of the heating coil 11, the direction of the cooling fin 20 and its 180
It is possible to prevent the magnetic field on the opposite side from becoming stronger than the other directions and the directivity from becoming stronger, and to suppress the leakage magnetic field.

As described above, since the ferrite powder is mixed in the coil holder 27, the work of adhering the rod-shaped magnetic body can be omitted and the assembly cost can be reduced. Further, since the rod-shaped ferrite cores 28a, 28b are used as means for relaxing the directivity of the magnetic field generated from the heating coil 11 and making it close to non-directional, the coil holding base 27 is shared with a model having a different main body configuration or different component arrangement. This facilitates the production of the coil holding bases 27. As a result, the coil holding table 27 in which the ferrite powder is mixed is
The production cost can be reduced by reducing the depreciation cost of the production equipment.

(Embodiment 6) A sixth embodiment of the present invention will be described below with reference to FIG. FIG. 8 is a view of the heating coil 11 seen from the back side, in which the heating coil 11 is placed on a resin-made coil holding base 29, and the coil holding base 29 has an outer periphery of the heating coil 11 around the center of the heating coil 11. Seven rod-shaped ferrite cores 3 from the vicinity toward the center of the heating coil 11
0a to 30g are radially embedded and integrally molded. Further, the two ferrite cores 30h and 30i are fitted into and bonded to the recesses 29a and 29b provided in the coil holder 29, respectively. The embedded ferrite cores 30a to 30g are provided with an angular interval of about 45 degrees with the adjacent ferrite cores, and the distances from the heating coil 11 to the respective ferrite cores are made substantially equal to each other. It is provided so that the distances from the center to the ends of the respective ferrite cores are substantially equal. The ferrite core 30h is the ferrite core 30
The ferrite core 30i is arranged side by side with g, and the ferrite core 30i and the ferrite core 30a form an angle of about 45 degrees.

With the above structure, the ferrite cores 30a to 3a
Since 0 g is integrally molded, the time and effort for adhering it to the coil holding table 29 is unnecessary, and the manufacturing cost can be reduced in the case of mass production. Further, since the coil holding base 29 is provided with the concave portions 29a and 29b, the directivity of the magnetic field distribution from the heating coil 11 can be adjusted by bonding the ferrite cores 30h and 30i.

The directivity in the horizontal distribution of the magnetic field generated from the heating coil 11 when the heating coil 11 is incorporated in the main body casing to operate is caused by the influence of the conductive metal parts existing near the heating coil 11. However, it depends on the structure of the equipment and the arrangement of parts.

In the case of the present embodiment, the induction heating cooker of another model shares the heating coil 11 and the coil holder 29, the output of the other model is 1 kW, the heating coil current is small, and Since the components have little influence on the magnetic field distribution of the heating coil and the level of the leakage magnetic field generated from the heating coil is small, the ferrite cores 30h and 30i need not be attached. The output of this embodiment is as large as 2 kW and the current of the heating coil 11 is also large.
Since the cooling fin having a large shape is arranged close to the lower part of the magnetic field, the directivity of the magnetic field generated by the heating coil 11 may be increased. However, since the ferrite cores 30h and 30i are additionally provided, the magnetic field in a specific direction is increased. Can be prevented from becoming strong.

As described above, according to the present embodiment, the seven ferrite cores 30a to 30g are integrally formed with the coil holder and the two ferrite cores 30h and 30i fixed by the adhesive are additionally provided. By the heating coil 11
Since it is used as a means for relaxing the directivity of the magnetic field distribution generated from the coil holder 29, the ferrite core and the coil holder 29 are integrally molded, and the model and the coil holder 29 having different structures and outputs are formed.
To reduce costs by sharing and mass-producing
Moreover, it is possible to suppress the leakage magnetic field from the heating coil 11 from increasing in a specific direction.

(Embodiment 7) A seventh embodiment of the present invention will be described below with reference to FIG. In FIG. 9, the heating coil 11 is placed on the coil holder 30, and is screwed to the coil holder 30 so that the coil holder 13 sandwiches the periphery. About 1m around the heating coil 11
A shield ring 33 is provided by punching an aluminum plate having a thickness of m into a ring shape. Eight ferrite cores 31a to 31i are provided on the lower surface of the coil holder 30 to form the heating coil 1
The ferrite cores are radially provided around one center, and the ferrite cores other than the ferrite cores 31h are radially provided with an angular interval of about 45 degrees equal to that of the adjacent ferrite cores. The inner peripheral edge of the shield ring 33 is the coil holder 3
It is notched so as to avoid the screw tightening portion 32 of 0 and the protruding portion near the coil holder 13.

With the above structure, the magnetic flux generated from the heating coil 11 induces a current in the shield ring 33, which cancels the magnetic field of the heating coil 11 outside the shield ring 33 and leaks from the heating coil 11 to the surroundings. The magnetic field can be reduced. Further, since the notch is provided on the inner peripheral edge of the shield ring 33 to match the shape of the protrusion of the coil support base 30, the width of the shield ring 33 is widened to increase the total surface area, and the shield ring 33 is attached to the heating coil 11. Since they are closer to each other, the distribution of the current induced in the shield ring 33 can be widened, and the amount of induced current in the shield ring 33 can be increased, so that the above-described magnetic field leakage reduction effect can be enhanced.

Further, due to the notch of the shield ring 33, the distribution of the current induced in the shield ring 33 is not uniform over 360 degrees around the heating coil 11, so that the magnetic field distribution around the heating coil 11 is uniform. In a specific direction (in this case the shield ring 3
The magnetic field becomes stronger in the direction of the large notch provided in 3 and the direction opposite to that of 180 degrees), and directivity is generated, but the angle formed by the three ferrite cores 31g, 31h, and 31i is adjacent to other ferrite cores. By making the distribution density of the ferrite core smaller than the angle to increase the distribution density of the ferrite core and suppressing the magnetic field strength in a specific direction to approach non-directionality, the leakage magnetic field can be further reduced.

As described above, according to the present embodiment, the shield ring 33, which is continuously provided near the outer periphery of the heating coil 11 and generates an induced current by the magnetic flux generated by the heating coil, is provided in the shape of the coil support base 33. In addition, a notch is provided in the inner peripheral portion of the shield ring 33 so that the distance between the shield ring 33 and the heating coil is partially increased, and the heating coil 11 and the inner peripheral portion of the shield ring 33 are brought close to each other in other portions. Moreover, by increasing the distribution density of the ferrite core 31 in the specific direction, the leakage magnetic field generated from the heating coil 11 can be suppressed more effectively.

In the seventh embodiment, the distribution density of the ferrite core 31 is changed depending on the direction in order to make the magnetic field distribution close to omnidirectional. However, the magnetic coupling between the ferrite core 31 and the heating coil 11 is set in a specific direction. May be made different, or the shape of the ferrite core 31 may be made different in a specific direction.

In addition, in the seventh embodiment, the shield ring 3
Although the notch is provided inside 3, the notch is provided outside or the width of the shield ring 33 is not constant, or the shape of the inner circumference or the outer circumference of the shield ring 33 is similar to the shape of the heating coil 11. Even if it is not set, the leakage magnetic field can be reduced by setting the shape and arrangement of the ferrite core 31 as described above.

The shield ring 33 is 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.

[0095]

As described above, according to the present invention, the heating coil is located near the heating coil on the side opposite to the side where the load is located, with a space provided around the center of the heating coil. The angle formed by two or more adjacent magnetic bodies of one or more of the plurality of magnetic bodies is smaller than the angle formed by the other two magnetic bodies next to each other. By providing a directivity relaxing means for the magnetic field distribution generated from the heating coil with a large distribution density, the leakage magnetic field in all directions around the magnetic field leaking from the heating coil can be seen from the center of the heating coil as in the past. Unlike the one that obtains the effect of uniformly reducing the leakage magnetic field, the sharp magnetic field distribution leaking from the heating coil to the surroundings is made non-directional, and the leakage magnetic field that becomes particularly strong in a specific direction is reduced. By doing so, it is possible to reduce the magnetic field leaking from the equipment, and it is possible to have a simple configuration when assembling, there is little influence on the oscillation waveform of the frequency conversion device such as an inverter and the cooling effect inside the equipment, and it is cheap and compact. In addition, it is possible to provide an induction heating cooker with a small leakage magnetic field.

Further, a plurality of magnetic materials having the same shape are distributed around the substantially center of the heating coil along the heating coil with a substantially equal angular difference, and the frequency converter is incorporated into the housing to operate the frequency converter. By measuring the magnetic field distribution and arranging the magnetic materials so that the distribution density of the magnetic materials is higher in the vicinity of the direction where the magnetic field leaking from the heating coil is the strongest, the heating coil can be easily and efficiently. Thus, the magnetic field distribution leaking to the surroundings can be made non-directional to suppress the leak magnetic field.

Further, one of a plurality of magnetic bodies which are located in the vicinity of the heating coil on the side opposite to the side where the load is located and are arranged in the center direction from the vicinity of the outer periphery of the heating coil with a space around the center of the heating coil. By making the relative positional relationship between the specific magnetic body and the heating coil different from the relative positional relationship between the other magnetic body and the heating coil, the magnetic field distribution leaking from the heating coil to the surroundings is omnidirectional. Since it is possible to reduce the leakage magnetic field by approaching the heating coil, it is not necessary to add a component that occupies a large space in the vicinity of the heating coil, and the influence on the oscillation waveform of the frequency conversion device such as an inverter and the cooling effect inside the device is eliminated. Therefore, it is possible to provide an induction heating cooker that is inexpensive, small, and has a small leakage magnetic field.

Further, the induction heating cooker is configured such that the distance between one or more specific magnetic bodies of the plurality of magnetic bodies and the heating coil is smaller than the spacing between the other magnetic bodies and the heating coil. Since the magnetic field leaking to the surroundings can be suppressed, it is not necessary to dispose a shield member in the adjacent space around the heating coil, and the device can be downsized.

Further, a plurality of magnetic bodies having the same shape are distributed around the substantially center of the heating coil with a substantially equal angle difference along the heating coil, and the frequency converter is incorporated into the housing to operate the frequency converter. Measure the magnetic field distribution and, in the vicinity of the direction in which the magnetic field leaking from the heating coil is strongest, make the distance between the magnetic body and the heating coil smaller than the distance between the magnetic body and the heating coil in other directions. Since the arrangement is determined, the magnetic field distribution leaking from the heating coil to the surroundings can be easily and efficiently approached non-directionally to suppress the leak magnetic field.

Further, by arranging the position of one or more specific magnetic members of the plurality of magnetic members so as to be displaced to the outside or inside of the heating coil in the radial direction relative to the positions of the other magnetic members. Since it is possible to suppress the magnetic field leaking from the induction heating cooker to the surroundings, it is possible to reduce the space in the direction in which the magnetic material is present as viewed from the heating coil, and it is possible to make the device thin and compact. It will be.

Further, a plurality of magnetic bodies of the same shape are distributed around the substantially center of the heating coil along the heating coil with a substantially equal angular difference and incorporated into the housing, and the frequency converter is operated to operate the heating coil. In the vicinity of the direction in which the magnetic field leaking from the coil becomes the strongest when viewed from the approximate center of the heating coil, the magnetic material is arranged so that the position of the magnetic material protrudes in the radial direction of the heating coil relative to the positions of other magnetic materials. Therefore, the magnetic field distribution leaking from the heating coil to the surroundings can be easily and efficiently approached in a non-directional manner to suppress the leak magnetic field.

Further, among a plurality of magnetic bodies which are located in the vicinity of the heating coil on the side opposite to the side where the load is located and which are arranged around the center of the heating coil and spaced from the vicinity of the outer periphery of the heating coil in the substantially central direction. By making the shape of one or more magnetic bodies different from the shape of other magnetic bodies and using the directivity relaxing means of the magnetic field distribution generated from the heating coil, without complicating the configuration in the vicinity of the heating coil, It is possible to suppress the leakage magnetic field, so there is little influence on the oscillation waveform of the frequency conversion device such as an inverter or the cooling effect inside the device,
It is possible to provide an inexpensive, small-sized induction heating cooker with a small leakage magnetic field.

Further, a plurality of magnetic materials having the same shape are distributed around the substantially center of the heating coil with a substantially equal angular difference along the heating coil and incorporated into the housing to operate the frequency conversion device. Determine the layout and shape of the magnetic material so that the length or cross-sectional area of the magnetic material is larger in the vicinity of the direction in which the leaking magnetic field becomes the strongest when viewed from the approximate center of the heating coil, compared to magnetic materials in other directions. Thus, the magnetic field distribution leaking from the heating coil to the surroundings can be easily and efficiently approached non-directionally to suppress the leak magnetic field.

Further, the distribution density is made higher in the vicinity of the direction in which the cooling fins of the power semiconductor of the frequency conversion device are located when the plurality of magnetic bodies are viewed from the approximate center of the heating coil, or the distribution density of the magnetic bodies and the heating coil is increased. Leakage from the heating coil to the surroundings by reducing the distance between the two, or by arranging the position of the magnetic material so as to project in the radial direction of the heating coil, or by increasing the length or cross-sectional area of the magnetic material. The magnetic field distribution can be made non-directional, and the magnetic field leaking from the heating coil to the surroundings can be suppressed without complicating the parts configuration near the heating coil, and the induction heating cooker can be made smaller and thinner. be able to.

Further, the heating coil holding portion is molded from a mixed material of magnetic powder and insulating resin material, and the magnetic material is distributed on the heating coil holding portion side in a certain direction when viewed from the center of the heating coil, and heated. By using the directionality reducing means of the magnetic field distribution generated from the coil, the magnetic field distribution leaking from the heating coil to the surroundings can be made non-directional, and the leakage magnetic field can be suppressed. It is possible to reduce the size and production cost.

Further, a part of the plurality of magnetic bodies is integrally formed with the heating coil holding portion, and the other magnetic bodies are fixed to the heating coil or the heating coil holding portion or other parts by fixing means other than integral molding. The magnetic field distribution generated by the heating coil can be reduced to a non-directivity by suppressing the leakage magnetic field by making the magnetic field distribution directivity mitigating means close to omnidirectional. The production cost can be reduced.

Further, a plurality of magnetic bodies are formed in a rod shape having substantially the same shape, and the magnetic body integrally formed with the heating coil holding portion forms an angle with another adjacent integrally formed magnetic body, which are all substantially the same or An integral multiple of the minimum value of the angle formed by one integrally formed magnetic body with another adjacent integrally formed magnetic body,
Moreover, since the one or more magnetic members are fixed between the integrally molded magnetic members by a fixing means other than the one integrally formed with the heating coil holding portion, the magnetic field distribution leaking from the heating coil to the surroundings is made non-directional. It is possible to easily suppress the approaching leakage magnetic field and reduce the production cost.

Further, the heating coil is continuously provided near the outer circumference,
The magnetic shield conductive member that generates an induced current by the magnetic flux generated by the heating coil, and the distribution density of the magnetic material is increased in a specific direction when viewed from the approximate center of the heating coil, compared to other directions, or By changing the relative positional relationship between the heating coil and the heating coil, or by changing the shape of the magnetic body, the directivity of the magnetic field distribution by the heating coil and the conductive member for the magnetic shield approaches non-directionality, and the conductive member for the magnetic shield. The effect of reducing the leakage magnetic field can be made more effective, and an induction heating cooker with a small magnetic field leaking from the heating coil to the surroundings can be provided.

[Brief description of the drawings]

FIG. 1A is a side sectional view of an induction heating cooker according to a first embodiment of the present invention, and FIG. 1B is a plan view of a main portion of the induction heating cooker.

FIG. 2 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 3 is a diagram showing the directivity of the magnetic field distribution of the induction heating cooker according to the second embodiment of the present invention.

FIG. 4A is a side sectional view of an essential part of an induction heating cooker according to a second embodiment of the present invention, and FIG. 4B is a plan view of an essential part of the induction heating cooker.

FIG. 5 is a plan view of an essential part of an induction heating cooker according to a third embodiment of the present invention.

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

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

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

FIG. 9 is a plan view of an essential part of an induction heating cooker according to a seventh embodiment of the present invention.

FIG. 10A is a plan view of a main part of a conventional induction heating cooker, and FIG. 10B is a side sectional view of the induction heating cooker.

[Explanation of symbols]

 11 heating coil 12 heating coil holder 13 coil holder 15 ferrite core 17 top plate 20 cooling fin

Front page continuation (72) Inventor Hirofumi Noma 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yuji Fujii, 1006 Kadoma, Kadoma City, Osaka (72) Invention Ogata Daizo 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (14)

[Claims] 1. A heating coil disposed near the load so as to face the load, a frequency conversion device for supplying a high-frequency current to the heating coil, and a heating coil located on the opposite side of the load from the heating coil. And a directivity alleviating means for magnetic field distribution having a plurality of magnetic bodies arranged in a substantially central direction from the vicinity of the outer periphery of the heating coil with a space provided around the center of the heating coil, the directivity alleviating means comprising: An induction heating cooker in which the angle between two adjacent magnetic bodies is changed according to the strength distribution of the magnetic field leaking from the heating coil. 2. A heating coil arranged near the load so as to face the load, a frequency conversion device for supplying a high-frequency current to the heating coil, and a heating coil located on the opposite side of the load from the heating coil. And a directivity alleviating means for magnetic field distribution having a plurality of magnetic bodies of the same shape, which are arranged in a substantially central direction from the vicinity of the outer periphery of the heating coil, with a space provided around the center of the heating coil. The means is an induction heating cooker in which the distribution density of the magnetic material is changed according to the intensity distribution of the magnetic field leaking from the heating coil. 3. A heating coil arranged near the load so as to face the load, a frequency conversion device for supplying a high-frequency current to the heating coil, and a heating coil located on the opposite side of the load from the heating coil. And a directivity alleviating means for magnetic field distribution having a plurality of magnetic bodies of the same shape, which are arranged in a substantially central direction from the vicinity of the outer periphery of the heating coil, with a space provided around the center of the heating coil. The means is an induction heating cooker in which the relative positional relationship between the magnetic body and the heating coil is changed according to the intensity distribution of the magnetic field leaking from the heating coil. 4. The induction cooking according to claim 3, wherein the directivity reducing means reduces the relative positional relationship between the heating coil and the magnetic body in the direction in which the intensity distribution of the magnetic field leaking from the heating coil is large. vessel. 5. The induction heating cooker according to claim 4, wherein the directivity alleviating means is provided with a magnetic body having substantially the same shape and having a substantially equal angular difference around the substantially center of the heating coil along the heating coil. . 6. A heating coil disposed near the load so as to face the load, a frequency conversion device that supplies a high-frequency current to the heating coil, and a heating coil located on the opposite side of the load from the heating coil. And a directivity alleviating means for magnetic field distribution having a plurality of magnetic bodies of the same shape, which are arranged in a substantially central direction from the vicinity of the outer periphery of the heating coil, with a space provided around the center of the heating coil. The means is an induction heating cooker in which the relative position of the magnetic body and the heating coil in the radial direction is changed according to the intensity distribution of the magnetic field leaking from the heating coil. 7. The directivity alleviating means is arranged so that, in the vicinity of the direction in which the magnetic field leaking from the heating coil is the strongest as viewed from the substantial center of the heating coil, the position of the magnetic body is higher than the positions of other magnetic bodies. The induction heating cooker according to claim 6, wherein the coil is arranged so as to protrude in the radial direction of the coil. 8. A heating coil arranged near the load so as to face the load, a frequency conversion device for supplying a high-frequency current to the heating coil, and a heating coil located on the opposite side of the load from the heating coil. And a directivity alleviating means for magnetic field distribution having a plurality of magnetic bodies of the same shape, which are arranged in a substantially central direction from the vicinity of the outer periphery of the heating coil, with a space provided around the center of the heating coil. The means is an induction heating cooker in which the shape of the magnetic body is changed according to the intensity distribution of the magnetic field leaking from the heating coil. 9. The induction heating cooker according to claim 8, wherein the directivity reducing means changes the length or the cross-sectional area of the magnetic material according to the intensity distribution of the magnetic field leaking from the heating coil. 10. The directivity alleviating means determines that the direction in which the cooling fins of the power semiconductor of the frequency conversion device are substantially positioned is the direction having the leakage magnetic field directivity. Induction heating cooker according to. 11. A heating coil arranged near the load in the vicinity of the load, a frequency converter for supplying a high-frequency current to the heating coil, a magnetic powder body holding the heating coil, and an insulating resin material. A heating coil holding part formed of the mixed material of, and located near the heating coil on the side opposite to the load, with a gap provided around the center of the heating coil, and arranged in a substantially central direction from the vicinity of the outer periphery of the heating coil And a directivity relaxing means for magnetic field distribution having a plurality of magnetic bodies of the same shape, wherein the directivity relaxing means applies the magnetic body to the heating coil according to the intensity distribution of the magnetic field leaking from the heating coil. An induction heating cooker that is distributed in a certain direction when viewed from the center. 12. A heating coil arranged near the load so as to face the load, a frequency conversion device for supplying a high-frequency current to the heating coil, a heating coil holder for holding the heating coil, and the load. Of the magnetic field distribution having a plurality of magnetic bodies of the same shape, which are located in the vicinity of the heating coil on the side opposite to An induction heating cooker comprising directivity relaxing means and at least one of the magnetic bodies formed integrally with the heating coil holder. 13. The angle formed by the magnetic body integrally formed with the heating coil holding portion and the other integrally formed magnetic body adjacent to each other is the same as that of the other integrally formed magnetic body adjacent to the magnetic body. 13. The induction cooking method according to claim 12, wherein the angle is approximately an integral multiple of the minimum angle among the formed angles, and at least one or more magnetic bodies that are not integrally formed are disposed between the integrally formed magnetic bodies. vessel. 14. The induction cooking according to any one of claims 1 to 13, wherein a conductive member for magnetic shield that generates an induced current by a magnetic flux generated by the heating coil is provided near the outer periphery of the heating coil. vessel.