JPS6089094A - Induction heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a multi-layer wound induction heating device.

[Technical background of the invention and its problems] Multi-layer coils can be used to concentrate energy in 5 localized areas, perform local heating, increase coil voltage, reduce wiring current to reduce loss, and power supply. It is used when harmonizing with voltage. Achieving these objectives 4: Because the main focus was placed on achieving these objectives, no consideration was given to improving efficiency. Therefore, in a multilayer coil, there is only one space between the layers! JiF
i (1 to am) was selected as long as the insulator could be inserted.

An embodiment of the invention is shown in FIG. This is the heating coil (2
2 shows a cross section of the heating material 1 (layered winding) and the heating material 1. Among the magnetic fluxes generated by the outer layer coil 2 and the inner layer coil 3, Φl is an effective magnetic flux interlinking with the heating material, and ΦB and Φ8 are leakage magnetic fluxes. In the multilayer coil, Φ8 interlinks with other conductors, causing loss in the conductor itself.

The current flowing through the conductor is concentrated in the shaded area in FIG. 1, depending on the depth of current penetration due to one frequency of resistivity.

Therefore, Joule loss occurring at the depth of current penetration and eddy current loss due to Φ8 occur in the conductor. Second
The figure shows the loss distribution. p□ is the inner layer and outer layer coil 2.
3, fig is the eddy current loss caused by the leakage magnetic flux Φ8, and pi is the eddy current loss caused by Φl generated in the heating material 1.

The eddy current loss p caused by the leakage magnetic flux Φ8 reduces the coil efficiency.

[Object of the invention] To provide an energy-saving induction heating device with improved coil efficiency.

[Summary of the Invention] The present invention provides an inner layer coil wound around a heated material;
This inner layer coil is wound approximately concentrically on the outside, and an outer layer coil is installed with a gap between the inner layer coil and the inner layer coil that is at least twice the depth of current penetration in the inner layer coil. . That is, the present invention is a multilayer induction heating device characterized in that induction heating coil steel pipes are formed with gaps at least twice the depth of current penetration.

Note that the depth of current penetration is generally calculated using the following formula.

Depth of current penetration" 5030
2) For example, the heating coil is a steel pipe (ρ-2X 1010-6O-
If the frequency is 500Hz, the current penetration depth = 5030 x 2x10-'1500 = 0.
318 (,).

[Embodiments of the Invention] Next, embodiments of the present invention will be described. Figure 1 shows the inner layer coil 3 wound around the heated material and the inner layer coil 3.
An induction heating device comprising: an outer layer coil 2 wound approximately concentrically on the outside and attached with a gap G between the inner layer coil 3 and the inner layer coil 3 which is at least twice the depth of current penetration into the inner layer coil 3. It shows.

The coil is characterized in that the coil steel pipes are arranged so that the distance G between the outer surface of the inner layer coil 3 and the inner surface of the outer layer coil 2 is at least twice the depth of current penetration. A steel pipe is used for the coil, and a spacing piece 5 made of an insulator is inserted to maintain the distance between the inner layer coil 3 and the outer layer coil 20.

The present invention can also be applied to vertical magnetic flux heating coils. As shown in FIG. 3, the present invention also includes the use of upper and lower coils, or only one of them, which has an iron core 4 and is arranged so that the magnetic flux passes perpendicularly to the heating material.

Further, although the embodiment is a two-layer coil, three or more layers are also included in the present invention.

[Effects of the Invention] By making the interval between the outer layer coil 2 and the inner layer coil 3 twice or more the depth of current penetration, the eddy current loss occurring in the inner layer coil 3 can be greatly reduced. This is because the increased spacing makes it easier for magnetic flux to pass through the spacing, reducing magnetic flux interlinking with the steel pipe and reducing eddy currents.

In our experiments, we were able to reduce eddy current loss by at least 30%. Heating material shape 9 dimensions material, power frequency.

Although the effect obtained varies depending on the coil dimensions, the energy saving effect is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the induction heating device of the present invention, Fig. 2 is an explanatory diagram of the distribution of copper loss and eddy current loss occurring in the steel pipe of the multilayer coil, and Fig. 3 is a cross-sectional view of the induction heating device with an iron core. It is a diagram. 1... Heating material 2... Outer layer coil 3... Inner layer coil 4... Iron core 5... Spacing piece agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1

Claims (1)

[Claims] An inner layer coil wound around a material to be heated, and an inner layer coil wound approximately concentrically with the inner layer coil on the outside, with a gap between the inner layer coil and the inner layer coil being at least twice the depth of current penetration in the inner layer coil. An induction heating device comprising an attached outer layer coil.