JPH0722170A - Induction heating cooking apparatus - Google Patents

Abstract

PURPOSE:To provide an induction heating cooking apparatus which can be accomplished at a low cost and in which the magnetic field leaking peripherally from the heating coil is less. CONSTITUTION:Closed loops are formed from a conductive wire and a plurality of shield members 20 are mounted in layers on an electric wire mounting part 19 provided on the outer side face of a heating coil holding table 13. The high frequency magnetic field of a heating coil 15 is in interlinkage with the shield members 20 to induce therein a high frequency current, which generates a magnetic field, and thereby the magnetic field leaking peripherally from the heating coil 15 is suppressed. Laminating of a plurality of shield members 20 increases the magnetic flux which sets off the magnetic field of the heating coil 15. Formation of the conductive wire in closed loops permits simplifying the configuration and allows reduction of the material costs.

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 leaked to the surroundings from a heating coil.

[0002]

2. Description of the Related Art In recent years, induction heating cookers that induce eddy currents in the bottom of a load pan by a high-frequency magnetic field for heating have been designed to have a high output, and it has become necessary to suppress the magnetic field leaking to the surroundings. There is.

Conventionally, as a magnetic shield means for suppressing a magnetic field leaking from the heating coil of an induction heating cooker of this kind to the surroundings, a structure as disclosed in Japanese Patent Laid-Open No. 57-115795 has been known.

The structure will be described below with reference to FIG. As shown in the figure, a disk-shaped heating coil 1 is placed on a heating coil holder 2 and the coil holder 3 fixes the heating coil 1 so that the surroundings of the heating coil 1 are not fixed and is made of a conductive material such as aluminum. A ring 4 having an inverted L-shaped cross section is provided around the heating coil 1. Then, the heating coil holder 2 is fixed to a column 7 provided on the bottom surface of the housing 5,
The heating coil 1 is located below the top plate 8 on which the load pan is placed. The ring 4 is manufactured by stamping out an aluminum plate in a donut shape and then molding it into a reverse L-shape by a mold.

In the above structure, when a high frequency current is supplied to the heating coil 1, the high frequency current is induced in the ring 4 by the magnetic field generated by the heating coil 1. The magnetic field generated by the high-frequency current induced in the ring 4 strengthens the magnetic field generated by the heating coil 1 inside the ring 4, and becomes the magnetic field in the opposite direction to the magnetic field generated by the heating coil 1 outside the ring 4. The magnetic field leaking toward one side is reduced.

[0006]

In such a conventional induction heating cooker, an aluminum plate is punched out in a donut shape in order to manufacture the ring 4, so that the central portion of the plate must be discarded, and the original plate as a material. Since it is usually a quadrangle, it is necessary to discard the four corners punched out in a circular shape, which reduces the efficiency of use of the material, raises the cost of the material, and increases the processing cost because it is molded with a die, so the ring 4 There was a problem that the cost of was extremely high.

The present invention is intended to solve the above problems, and it is a first object of the present invention to provide a low-cost induction heating cooker capable of reducing a magnetic field generated from a heating coil and leaking to the surroundings. There is.

A second object of the present invention is to provide an induction heating cooker capable of preventing the generation of noise due to the vibration of the magnetic shield conductive member.

[0009]

In order to achieve the above object, the first means of the present invention is to form a magnetic shield conductive member in a closed loop shape by connecting conductive wires covered with an insulating member at both ends. Then, a plurality of them are stacked and mounted on a mounting portion formed on the outer surface of the heating coil holder.

The second means is to form a magnetic shield conductive member with a conductive wire and mount it in a groove formed in the peripheral portion of the heating coil holder, and connect both ends thereof to form a closed loop. It is configured to have a shape.

A third means is to form a magnetic shield conductive member in a closed loop shape by connecting both ends of a belt-shaped conductive plate, and to a mounting portion formed on the outer surface of the heating coil holder. While being mounted, an adhesive or a synthetic resin having elasticity is interposed between the magnetic shield conductive member and the mounting portion.

A fourth means is to form the magnetic shield conductive member by a solenoid of a closed loop having a plurality of turns having both ends connected, and to mount it on a solenoid mounting portion formed on an outer surface of the heating coil holder. A synthetic resin or adhesive having elasticity is interposed between the solenoid and the mounting portion.

[0013]

In the structure of the first means, the conductive member for magnetic shield is formed on the outer surface of the heating coil holder by forming the conductive wire in a closed loop shape, so that the high frequency magnetic field generated by the heating coil is magnetic. A high-frequency current is induced in the conductive wire by interlinking the shield conductive members. A magnetic field is generated by this conductive current and suppresses a magnetic field leaking from the heating coil to the surroundings. Furthermore, by stacking a plurality of magnetic shield conductive members and mounting them on the wire mounting portion provided on the outer surface of the heating coil holding member, the demagnetizing flux that cancels the magnetic field of the heating coil is increased and the demagnetizing flux is generated. Since the distribution of the current source is geometrically widened, the magnetic shielding effect is improved.

In the structure of the second means, the conductive wire is mounted in the groove provided in the peripheral portion of the heating coil holder to form the closed loop magnetic shield conductive member wound a plurality of times. Similarly to the first means, the anti-magnetic flux that cancels the magnetic field of the heating coil generated by the induced current increases, and the distribution of the current sources that generate the anti-magnetic flux is geometrically widened, so that the magnetic shielding effect is improved.

In the structure of the third means, the magnetic shield conductive member is formed on the outer surface of the heating coil holder by forming a belt-shaped conductive plate in a closed loop shape, and an adhesive or a synthetic resin having elasticity is used. By interposing,
The vibration of the magnetic shield conductive member caused by the interaction between the current of the heating coil and the current induced in the magnetic shield conductive member is buffered to eliminate the contact with the heating coil holder.

In the structure of the above-mentioned fourth means, the magnetic shield conductive member is formed of a closed loop solenoid and mounted on the outer surface of the heating coil holder, and an adhesive or a synthetic resin having elasticity is interposed. As a result, as in the case of the first means, the anti-magnetic flux that cancels the magnetic field of the heating coil generated by the induced current increases, and the distribution of the current sources that generate the anti-magnetic flux geometrically widens, so the magnetic shielding effect is improved. To do. Further, similarly to the third means, the vibration of the magnetic shield conductive member caused by the interaction between the current of the heating coil and the current induced in the magnetic shield conductive member is buffered so that the contact with the heating coil holder is eliminated. To do.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG.

As shown in FIGS. 1 (a) and 1 (b), a heating coil holding base 13 is placed on a column 12 provided on the bottom surface of a resin case 11 and fixed by screws 14. ing. A heating coil 15 is placed on the heating coil holder 13, and a ceramic top plate 16 is disposed on the heating coil 15. A peripheral portion of the heating coil 15 is pressed and fixed to a heating coil holding base 13 by a coil holder 17, and a high frequency current is supplied from a frequency conversion device 18 such as an inverter arranged in the housing 11.

A vertical groove-shaped electric wire mounting portion 19 is formed on the outer surface of the heating coil holder 13, and the electric wire mounting portion 19 has a plurality of magnetic shield conductive members (hereinafter referred to as shield members) 20a, 20b. 20c and 20d are vertically stacked and mounted. Further, the opening of the electric wire mounting portion 19 is locally formed with a narrow gap.

The shield members 20a, ..., 20d are covered with a synthetic resin having flexibility and electrical insulation such as silicone resin or heat-resistant vinyl chloride around the conductive wire. Then, as shown in FIG. 1B, the coatings on both ends of the coated electric wire are peeled off and pressure-connected by the connector 21 to form a loop shape. The connector 21 is adapted to be inserted into a cutout portion 22 provided on the outer wall of the electric wire mounting portion 19.

In the above structure, when a high frequency current is supplied to the heating coil 15 from the frequency converter 18, a magnetic field is generated from the heating coil 15. This magnetic field interlinks with, for example, an iron pot placed on the top plate 16 to generate an eddy current in the pot, which causes the pot to generate heat due to Joule heat.

On the other hand, the magnetic field generated from the heating coil 15 also interlinks with the closed curved surface formed by the shield members 20a, ..., 20d to generate an induced current in the shield members 20a ,. This induced current is applied to the shield members 20a, ... 20
Inside d, in the same direction as the magnetic field of the heating coil 15,
In addition, since a magnetic field in the opposite direction is generated outside,
A magnetic field generated from the heating coil 15 and leaking to the surroundings can be suppressed.

In this case, the plurality of shield members 20a, ...
Since 20d is vertically stacked, the heating coil 1
The current for suppressing the magnetic field of No. 5 becomes almost equivalent to flowing through the cylindrical shield member, and the effect of effectively reducing the magnetic field leaking from the heating coil 15 to the surroundings can be obtained.

Further, since the shield members 20a, ... 20d are formed by press-connecting both ends of the covered electric wire with the connector 21, the manufacture is easy, and the shield member 20a, ... In comparison, the effect that the material utilization efficiency can be increased is obtained.

Further, since the shield members 20a, ..., 20d are coated with a flexible synthetic resin around the conductive wires, the current flowing through the conductive wires and the current flowing through the heating coil 15 interact with each other. Even if the conductive wire vibrates, no annoying noise generated by touching the heating coil holding base 13 is generated, and the opening of the wire mounting portion 19 has a locally narrowed gap, so that the shield is provided. An effect that the members 20a, ..., 20d are not separated from the electric wire mounting portion 19 is obtained.

The outer wall 19a of the wire mounting portion 19 may be partially formed like the mounting portion shown in FIG. 20d may be interposed between the shield members 20a, ..., 20d and the electric wire mounting portion 19 to prevent vibration of the shield members 20a ,.

As described above, according to the first embodiment of the present invention, the electric wire mounting portion 19 formed on the outer surface of the heating coil holder 13 has a plurality of closed loop shield members 20a covered with an insulating member. … By stacking 20d,
The magnetic field leaking from the heating coil 15 to the surroundings can be reduced effectively and at low cost.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG.

Only the structure different from that shown in the first embodiment will be described. As shown in the drawing, a groove 23 is formed on the upper surface and the side surface of the peripheral portion of the heating coil holder 13 on which the heating coil 15 is mounted. The groove 23 is formed in a spiral shape or in an annular shape that communicates with each other, and one conductive wire 24 is mounted in the groove 23. The starting end and the terminating end of the conductive wire 24 are connected by an appropriate means to form a closed loop coil having a plurality of turns.

In the above structure, the heating coil holder 13
Since both ends of the conductive wire 24 wound around the upper surface and the side surface of the conductive wire 24 are connected to each other, an induced current flows through the conductive wire 24 due to the magnetic flux from the heating coil 15, and similar to the one shown in the first embodiment. The induced current reduces the magnetic field leaking from the heating coil 15 to the surroundings. Further, the conductive wire 24 is the heating coil holder 1.
Since it is widely arranged from the upper surface to the side surface of 3, the effect of reducing the leakage magnetic field becomes large. Further, since the heating coil holding base 13 is provided with the groove 23 and the conductive wire 24 is mounted in the groove, it is not necessary to cover the conductive wire 24 with an insulator, and the work of peeling the insulator when connecting both ends can be performed. It becomes unnecessary.

When the conductive wire 24 is mounted in the groove 23, a resilient synthetic resin or adhesive may be interposed between the two to prevent the conductive wire 24 from vibrating. Further, the groove 23 may be formed only on one of the upper surface and the side surface of the heating coil holding base 13 and the conductive wire 24 may be attached thereto.

As described above, according to the second embodiment of the present invention, the conductive wire 24 is attached to the groove 23 provided in the peripheral portion of the heating coil holder 13 to form a closed loop coil having a plurality of turns. The magnetic field leaking from the heating coil 15 to the surroundings can be effectively reduced, and the conductive wire 2
Since it is not necessary to apply an insulating coating to the wiring 4, the cost of the conductive wire 24 can be reduced. Further, there is an effect that it is possible to save the labor of peeling the insulating coating when connecting both ends of the conductive wire 24.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to FIG.

Only the structure different from that shown in the first embodiment will be described. As shown in the figure, a vertical groove-shaped mounting portion 25 is formed on the outer surface of the heating coil holding base 13 to which the heating coil 15 is mounted, and a ring-shaped shield member 26 is mounted on the mounting portion 25. There is. Further, a plurality of local narrow portions 27 for sandwiching the shield member 26 are provided at the opening of the mounting portion 25.

The shield member 26 is formed in a closed loop shape by winding a band-shaped conductive plate in a ring shape and connecting both ends 28 by appropriate means. Further, between the shield member 26 and the mounting portion 25, a synthetic resin or an adhesive having elasticity, for example, a silicone rubber-based filler or an adhesive is provided on the entire surface or at several places.

In the above structure, since both ends 28 of the shield member 26 are connected, an induced current flows in the shield member 26 due to the magnetic flux from the heating coil 15, and the shield member 26 has the same structure as that shown in the first embodiment. The induced current reduces the magnetic field leaking from the heating coil 15 to the surroundings. Further, since the shield member 26 is formed in a ring shape by connecting both ends of the strip-shaped conductive plate, the material to be discarded in the production of the shield member 26 is extremely reduced, and the material cost can be reduced. Further, the shield member 26 is sandwiched by the narrow portions 27, and synthetic resin or adhesive having elasticity is interposed on the entire surface or at several places between the shield member 26 and the mounting portion 25 to eliminate rattling of the shield member 26. Therefore, the vibration of the shield member 26 due to the interaction between the current induced in the shield member 26 and the current flowing in the heating coil 15 is suppressed,
It is possible to prevent generation of noise due to contact of the shield member 26 with the heating coil holding base 13.

The mounting portion 25 may be partially formed like the mounting portion shown in FIG.

As described above, according to the third embodiment of the present invention, the mounting portion 2 formed on the outer side surface of the heating coil holding base 13 is formed.
A closed loop shield member 26 formed by molding a belt-shaped conductive plate into a ring shape is attached to the member 5, and a synthetic resin or an adhesive having elasticity is interposed between the shield member 26 and the attaching portion. It is possible to effectively reduce the magnetic field leaking from the surroundings to the surroundings and reduce the material cost of the shield member 26. Further, there is an effect that it is possible to prevent the generation of noise due to the vibration of the shield member 26.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG.

Only the structure different from that shown in the first embodiment will be described. As shown in the figure, a plurality of L-shaped mounting pieces 29 having an open top are provided on the outer surface of the heating coil holder 13. Then, a recessed portion 30 is provided on the inner surface thereof, and a shield member 31 is attached to the recessed portion 30. The shield member 31 is formed by a closed loop solenoid in which a conductive wire is wound a plurality of turns and both ends thereof are connected by connectors 32. Further, between the shield member 31 and the heating coil holding base 13, a synthetic resin or an adhesive having elasticity, for example, a silicone rubber-based filling material or an adhesive is provided on the entire surface or at several places. .

In the above structure, since both ends of the solenoid, which is a shield member, are connected, an induced current flows through the shield member 31 due to the magnetic flux from the heating coil 15, and the solenoid is the same as that shown in the first embodiment. The induced current reduces the magnetic field leaking from the heating coil 15 to the surroundings. In this case, since the solenoid is wound a plurality of turns, its reducing effect becomes large. Further, the shield member 31 is sandwiched by the mounting pieces 29, and the synthetic resin or adhesive having elasticity is interposed on the entire surface or at several places between the shield member 31 and the heating coil holding base 13 to prevent rattling of the shield member 31. Since it is eliminated, the vibration of the shield member 31 due to the interaction between the current flowing through the heating coil 15 and the current induced in the shield member 31 is prevented, and the generation of noise due to the contact between the shield member 31 and the heating coil holding base 13 is prevented. Can be prevented.

As described above, according to the fourth embodiment of the present invention, the shield member 31 formed of a closed loop solenoid is attached to the mounting piece 29 provided on the outer surface of the heating coil holding base 13.
By mounting and by interposing the elastic synthetic resin or adhesive between the shield member 31 and the heating coil holder 13, the magnetic field leaking from the heating coil 15 to the surroundings can be effectively reduced. At the same time, it is possible to prevent the generation of noise due to the vibration of the shield member 31.

[0044]

As is apparent from the above description of the embodiments, according to the present invention, a plurality of closed-loop shields, each of which has an electric wire mounting portion formed on the outer surface of the heating coil holder, is covered with an insulating member. By stacking and mounting the members, the magnetic field leaking from the heating coil to the surroundings can be effectively reduced at low cost.

Further, since the conductive wire is attached to the groove provided in the peripheral portion of the heating coil holder to form a closed loop coil having a plurality of turns, the magnetic field leaking from the heating coil to the surroundings can be effectively reduced. In addition, since it is not necessary to apply an insulating coating to the conductive wire, the cost of the conductive wire can be reduced.

Further, it is possible to save the trouble of peeling the insulating coating when connecting both ends of the conductive wire. In addition, a closed-loop shield member formed by molding a band-shaped conductive plate into a ring shape is attached to the attachment portion formed on the outer surface of the heating coil holder, and a synthetic resin or adhesive having elasticity is attached between the shield member and the attachment portion. By interposing the agent, it is possible to effectively reduce the magnetic field leaking from the heating coil to the surroundings,
The material cost of the shield member can be reduced. Furthermore, it is possible to prevent the generation of noise due to the vibration of the shield member.

Further, a shield member composed of a closed-loop solenoid is attached to an attachment piece provided on the outer surface of the heating coil holding base, and an elastic synthetic resin or an adhesive is placed between the shield member and the heating coil holding base. By interposing, it is possible to effectively reduce the magnetic field leaking from the heating coil to the surroundings, and it is possible to prevent the generation of noise due to the vibration of the shield member.

As described above, according to the present invention, the magnetic field generated from the heating coil and leaking to the surroundings can be reduced, the cost can be reduced, and the noise due to the vibration of the shield member can be prevented. It is possible to provide an induction heating cooker capable of performing the above.

[Brief description of 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 an exploded perspective view of the main part thereof.

FIG. 2 is a side sectional view of a main part of an induction heating cooker according to a second embodiment of the present invention.

FIG. 3 is an exploded perspective view of a main part of an induction heating cooker according to a third embodiment of the present invention.

FIG. 4 is an exploded perspective view of a main part of an induction heating cooker according to a fourth embodiment of the present invention.

FIG. 5 is a side sectional view of a conventional induction heating cooker.

[Explanation of symbols]

13 heating coil holder 15 heating coil 18 frequency converter 19 electric wire mounting portion 20a, 20b, 20c, 20d, 26, 31 shield member 23 groove 24 conductive wire 25 mounting portion 28 both ends 29 mounting piece

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

Claims (4)

[Claims] 1. A heating coil, a frequency conversion device for supplying a high-frequency current to the heating coil, a heating coil holding base formed of an electrically insulating member for holding the heating coil, and a heating coil holder provided around the heating coil. A magnetic shield conductive member that generates an induced current by the magnetic flux of the heating coil, and the conductive wire covered with an insulating member is connected at both ends to form a closed loop, and a plurality of the magnetic shield conductive members are formed. The induction heating cooker is characterized in that the heating coil holder is stacked and mounted on a mounting portion formed on the outer surface of the heating coil holding base. 2. A heating coil, a frequency conversion device for supplying a high frequency current to the heating coil, a heating coil holding base formed of an electrically insulating member for holding the heating coil, and provided around the heating coil. A magnetic shield conductive member that generates an induced current by the magnetic flux of the heating coil, and the magnetic shield conductive member is formed of a conductive wire and mounted in a groove formed in the peripheral portion of the heating coil holder. An induction heating cooker characterized in that both ends thereof are connected to form a closed loop. 3. A heating coil, a frequency converter for supplying a high-frequency current to the heating coil, a heating coil holding base formed of an electrically insulating member for holding the heating coil, and provided around the heating coil. A magnetic shield conductive member that generates an induced current by the magnetic flux of the heating coil, and the magnetic shield conductive member is formed into a closed loop by connecting both ends of a strip-shaped conductive plate, An induction heating cooker, which is mounted on a mounting portion formed on a side surface, and an adhesive or a synthetic resin having elasticity is interposed between the magnetic shield conductive member and the mounting portion. 4. A heating coil, a frequency conversion device for supplying a high frequency current to the heating coil, a heating coil holding base formed of an electrically insulating member for holding the heating coil, and provided around the heating coil. A conductive member for magnetic shield that generates an induced current by the magnetic flux of the heating coil, and the conductive member for magnetic shield is formed by a closed loop solenoid with a plurality of turns connecting both ends, and is formed on the outer surface of the heating coil holder. The induction heating cooker is characterized in that it is mounted on the solenoid mounting portion and a resilient synthetic resin or adhesive is interposed between the solenoid and the mounting portion.