JP2000223255A - Induction heating coil device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply compose a magnetic path having a shape running along an arbitrary curved surface on a surface of an induction heating coil opposite to its surface facing to a heated body. SOLUTION: The periphery of an induction beating coil 1 arranged on a surface of a heated body 2 is covered with flexible rubber 3 made by mixing magnetic powder of which surfaces each are coated with a non-conductive film. Since the magnetic powder is mixed in the rubber 3, the rubber 3 works as a magnetic path. The rubber 3 is flexible, so that it can be plastically deformed into a shape matching the periphery of the coil 1. Thereby, the magnetic path having a shape running along the periphery of the coil 1 is formed. By the formation of the magnetic path, a magnetic characteristic for induction heating is improved and the heated body 2 can be uniformly induction-heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coil device for induction heating.

[0002]

2. Description of the Related Art A disk coil formed by spirally winding an electric wire is used as an induction heating coil, which is installed so as to face a surface of a planar object to be heated (made of metal). A device has already been proposed in which the object to be heated is induction-heated by exciting it. According to this, an alternating magnetic flux generated by exciting the coil passes through the object to be heated, so that a current is induced in a direction intersecting with the alternating magnetic flux (a secondary current according to the principle of a transformer) and an eddy current. As a result, Joule heat is generated inside the object to be heated. This heat causes the heated body to generate heat.

[0003] However, according to the proposed structure, the coil is merely installed facing the surface of the object to be heated, and no magnetic path is provided on the outer surface of the coil. Therefore, a part of the generated magnetic flux leaks out from the middle of the coil without interlinking with all the coils. That is, a part becomes leakage magnetic flux. Therefore, not only does the magnetic characteristic deteriorate, but it becomes impossible to uniformly heat the object to be heated immediately below the coil.

In order to solve this problem, it is easily considered that a magnetic path may be provided on the surface opposite to the object to be heated with a coil interposed therebetween to absorb the leakage magnetic flux. It is generally considered that an iron core formed by stacking silicon steel plates is used to form this magnetic path. However, as a practical matter, the surface of the object to be heated is not necessarily a simple plane,
It may be a complex curved surface.

In such a case, the coil may be curved according to the curved surface, but it is extremely troublesome to install an iron core having a silicon steel sheet laminated on the surface of the curved coil. In addition, the iron core must be curved so as to match the curved surface, and its production is extremely difficult, and may not be possible depending on the degree of curvature.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a coil device used for induction heating a planar object to be heated.
It is an object of the present invention to form a magnetic path having a shape easily and along an arbitrary curved surface on an outer surface of a coil opposite to a surface facing a body to be heated.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a flexible coil made by mixing an outer surface of an induction heating coil disposed on the surface of a body to be heated with a magnetic powder having a surface coated with a non-conductive film. It is characterized by being covered with rubber.

[0008] The magnetic powder to be mixed has a surface coated with a non-conductive film and is electrically insulated. Therefore, even if these magnetic powders come into contact with each other, an electric circuit is not completed. The rubber is magnetized because magnetic powder is mixed in the rubber. Since this rubber is provided on the outer surface of the coil opposite to the object to be heated, it acts as a magnetic path for the generated magnetic flux.

[0009] Since this rubber is flexible, the rubber is plastically deformed on the outer surface of the coil disposed on the surface of the object to be heated according to the shape along the outer surface of the coil, and therefore, the surface of the object to be heated. Can be installed. With this arrangement, a magnetic path made of rubber is formed on the outer surface of the coil. That is, even if the shape of the surface of the coil or the object to be heated is any curved surface, a magnetic path conforming to the shape can be formed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 3, the coil used in the present invention is, for example, a disk coil 1 in which a rectangular electric wire is spirally wound. Note that in FIG.
Has two layers, but may be one layer or three or more layers. Although the disk coil 1 is circular as viewed in a plane in the figure, the disk coil 1 may have an elliptical shape or a polygonal shape such as a square.

The disk coil 1 is deformed and fixed according to the shape of the surface of the object to be heated. In order to fix the deformation and the deformation state, the following may be performed. That is, the surface of the electric wire (the surface of the insulating coating) is previously coated with a thermosetting resin. The disk coil formed by winding the electric wire is applied to the surface of the object to be heated or the surface of a mold having the same shape as the object to be pressed, and is deformed according to the surface. Thereafter, the disk coil is heated to cure the resin that has been coated in advance. Due to this hardening, the disk coil is fixed in the deformed state. Instead of this, a disk coil made of an electric wire (for example, a copper wire) may be plastically deformed as it is.

Disc coil 1 constructed as described above
Is placed on the surface of the metal body to be heated 2 as shown in FIG. Then, the rubber 3 is installed so as to cover the outer surface of the disk coil 1. As the rubber used here, a heat-resistant rubber which is deformable and flexible is used. For example, silicone rubber, Teflon rubber and the like are suitable.

As shown in FIG. 2, an appropriate amount of magnetic powder 4 such as iron or nickel, that is, an amount that satisfies magnetic path characteristics, is previously mixed into the rubber 3. The surface of the magnetic powder is coated with a non-conductive film such as an oxide film and an insulating rubber. Since the magnetic resistance of the rubber 3 is reduced by the magnetic powder mixed therein, the rubber 3 sufficiently functions as a magnetic path.

The rubber 3 containing the magnetic powder as described above is placed on the outer surface of the disk coil 1 placed on the surface of the object 2 to be heated. Plastically deformed to conform to the shape of
When the rubber 3 is provided, the rubber 3 and the object to be heated 1 form a magnetic path surrounding the disk coil 1.
This shape corresponds to a shell-type transformer. Here, when an AC power supply is connected to the disk coil 1 for excitation, the alternating magnetic flux generated thereby passes through the body to be heated 2 and returns through the mold portion 3 as a magnetic path.

By the rubber 3 acting as a magnetic path,
Almost all of the generated magnetic flux passes through the object to be heated 2 and the rubber 3, and thus links with the entire disc coil 1. Therefore, generation of leakage magnetic flux is reduced as much as possible. Thereby, compared to the case where the rubber 3 is not provided,
Since the magnetic properties are much improved, the induction heating efficiency of the heated body 2 is improved, and the surface of the heated body 2 facing the rubber 3 can be uniformly heated.

In this case, when the rubber 3 is provided so as to cover the entire outer surface of the disk coil 1, the surface of the heated body 2 facing the lower surface of the disk coil 1 can be uniformly heated. When the disk coil 1 is provided so as to partially cover the disk coil 1, a part of the surface of the heated body 2 facing the rubber 3 can be intensively and uniformly heated.

[0017]

As described above, according to the present invention, the outer surface of the induction heating disk coil disposed on the surface of the object to be heated is mixed with magnetic powder having a surface coated with a non-conductive film. Because the rubber is used as a magnetic path, even if the coil or the object to be heated is a curved surface, if the rubber is plastically deformed to fit the curved surface, In addition, a magnetic path having a shape following the curved surface can be easily formed, thereby improving the magnetic characteristics for induction heating and uniformly heating the object to be heated.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged plan view of rubbers used in the present invention.

FIG. 3 is a plan view and a sectional view of a disk coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc coil 2 Heated body 3 Rubber 4 Magnetic powder

Claims (1)

[Claims] A disk coil formed by winding an electric wire in a spiral shape is used as an induction heating coil, which is installed so as to face a surface of an object to be heated, and the coil is excited by an AC power supply to thereby provide a coil to be heated. In an induction heating coil device for inductively heating a heating body, an outer surface of the coil is covered with a flexible rubber containing a magnetic powder coated with a non-conductive film on the surface, and the rubber is covered with a magnetic path. Induction heating coil device.