JPS6144396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction heating device or an induction heating coil for an induction melting device used for heating or melting metal.

Since the operating temperature of such induction heating coils is high, they are generally water-cooled to protect insulation and for other purposes. In this case, in order to directly cool the coil conductor with water, the coil is often made of a hollow conductor with an integrally formed cooling water passage. When the length of the coil is short or when the cross-sectional area of the cooling water passage in the coil conductor is large, cooling water may be passed in series to one coil and only one cooling water circuit is required, but usually The cooling water circuit of one coil is often branched into multiple parts midway to form a plurality of parallel cooling water circuits. The reason for this is that compared to the case where the cooling water circuit of the coil consisting of M units is connected in series, when the cooling water circuit is connected in parallel, the amount of cooling water flowing through each unit is 1/M, so as is well known, the required cooling water head is 1 / ^M2 , but also because each unit is cooled equally. In this case, it is necessary to provide one coil with a plurality of branch ports for supplying and discharging cooling water. Since the branch port is drawn out to the outer periphery of the coil, in order to facilitate this drawing out, single-layer helically wound coils have been often used as induction heating coils. In addition, if the multilayer coil is concentrically wound, it becomes troublesome to draw out the cooling water branch port of the inner coil, and the winding work of the outer coil is done by avoiding the cooling water branch port of the inner coil. This not only makes it difficult to wind the coil, but also reduces the space factor of the coil.

However, when a current Ic is passed through the induction heating coil, a coil loss Pc (copper loss) occurs due to the coil resistance Rc of Pc = Ic ² ·Rc. The output of a heating coil is proportional to the product of the current flowing through the heating coil and the number of turns of the coil, or ampere-turns. When the ampere turns of the heating coil are constant, a coil with N-layer (multilayer) winding has a coil current Ic 1/N times higher and a coil resistance N times higher than a coil with a single-layer winding. Therefore, the loss Pc of an N-layer coil is (1/N) of the loss of a 1-layer coil ^{. 2}・N=1/N
It will be doubled. In reality, the length of the coil conductor wound in N layers is N times greater than that of a single layer coil, so the resistance is greater than N times, so the resistance and loss will not decrease to 1/N times, but in multilayer coils Then, it can be understood that the coil loss is smaller than that of a single layer coil with the same output.

The efficiency of a heating coil is expressed as (coil input - coil loss)/coil input, so if the coil loss can be reduced, the efficiency can be increased. Therefore, in terms of efficiency, a multilayer coil is more advantageous than a single layer coil as an induction heating coil.

In order to effectively utilize the advantages of the multilayer coil as described above, the present invention overcomes the drawbacks of the conventional multilayer coil, and provides a multilayer coil that is easy to manufacture and has a high coil space factor. The object is to provide a wound induction heating coil.

In order to achieve the above object, the present invention summarizes the following:
We adopted so-called twin coils to improve the efficiency of the heating coil, which is an advantage of multilayer winding, and
The idea is to connect the cooling water circuits of each twin coil in parallel to obtain electrically series-connected coils that drastically reduce the number of cooling water heads.

Embodiments of the present invention illustrated in the drawings will be described below.

1 and 2 show an embodiment of a coil unit used in the present invention. The coil unit has coil rows 1A and 1B formed by multiple windings of one common coil conductor 10 in two rows in a spiral shape. 10C is an intermediate portion of the coil conductor 10, and serves as a transition portion between the coil arrays 1A and 1B. The coil rows 1A and 1B are both spirally wound in multiple spirals from the inside to the outside, and both ends 10A and 10B of the coil conductor 10 appear at the outermost periphery of each coil row, forming a so-called twin coil. The ends 10A and 10B of the coil conductor are respectively raised in the radial direction and serve as connection ports for cooling water piping that also serve as electrical connection terminals for the coil. That is, when one end 10A is connected to a water supply pipe and cooling water is supplied from here to the coil conductor 10, it flows through the coil row 1A, moves from the transition section 10C to the coil row 1B, flows through this, and then flows through the coil conductor 10 to the other end. It comes to be discharged from the section 10B.

In such a coil unit 1 , as shown in FIG. 4, the middle part 10C of one coil conductor 10 is placed on a winding drum and winding starts from there to both ends, one end is left-handed and overlapped, and the other end is wrapped. It can be made extremely easily by winding it in layers in a right-handed manner.

FIG. 3 shows an embodiment of a heating coil for an induction heating device using such a coil unit. The plurality of coil units 1 , 1 ... 1 are
They are arranged close to each other in the axial direction. Coil conductor ends 10A and 10B, which serve as cooling water connection ports that also serve as electrical connection terminals for each coil unit, are connected in parallel to the water supply header 4 and drain header 5, respectively, and each coil unit is connected to the branched parallel cooling water. Configure the circuit. Electrically, all the coil units are connected in series by sequentially connecting one conductor end 10B of each coil unit to the other conductor end 10A of the adjacent coil unit through a connecting conductor 6. Of course, depending on the case, it is also possible to connect several coil units in series or in parallel. This also applies to the cooling water circuit. This constitutes one multilayer induction heating coil.

As described above, according to the present invention, since one cylindrical coil is configured as a plurality of twin coils connected in series, the induction heating coil becomes a multilayer wound coil, and the efficiency of the coil can be improved. Since the connection port for supplying and discharging cooling water is drawn out from the outermost periphery of each coil unit and connected in parallel, when the number of unit coils is M, the required cooling water head is drastically reduced to 1/ ^M2. do.

In other words, if the same flow rate of cooling water flows through all coils when connected in series, also when connected in parallel,
This is because when the coil units are connected in parallel, 1/M of cooling water flows through each coil unit, and the fluid resistance, that is, the new head, becomes 1/M ² . Moreover, the temperature rise among each coil unit becomes even. Furthermore, since this connection port does not interfere with adjacent unit coils, the coil can be easily manufactured and the space factor of the coil can be increased even though it is a multi-layered coil.

Therefore, in the induction heating coil of the present invention, even if the coils are connected in series, the cooling circuit can be parallelized to drastically reduce the cooling water head, that is, the cooling energy, the life of the coil is extended by equalizing the temperature rise, and the power efficiency is improved by multi-layer winding. This has the effect of making it possible to easily wind the coil and obtain a coil with a good space factor, despite the increased space factor.

[Brief explanation of the drawing]

Fig. 1 is a side view of the coil unit used in the present invention, Fig. 2 is a front sectional view thereof, Fig. 3 is a front view showing an embodiment of the present invention, and Fig. 4 is a perspective view showing the manufacturing process of the coil unit. It is a diagram. 1... Coil unit, 10... Coil conductor, 10
A, 10B... Coil conductor end, 10C... Coil conductor transition portion, 3... Winding drum, 4... Water supply header, 5
...Drain header, 6...Connection conductor.

Claims (1)

[Claims] 1. A coil conductor consisting of one hollow conductor, which is wound in two rows from the middle to both ends, and wound in multiple spirals so that both ends of the coil conductor appear at the outermost periphery of each row. In the case where a plurality of coil units are provided as a coil, and the plurality of coil conductors are arranged adjacent to each other in the axial direction, the cooling water circuits of each coil unit are connected in parallel, and the electric circuits of each coil unit are connected in series to form a single coil. An induction heating coil characterized by forming a cylindrical coil.