DE3049981A1 - An inductance coil having a core of magnetic material - Google Patents

Description

A 52

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Induction coil and method of making the same

The invention relates to an induction coil having a core in the form of a closed loop, in particular of circular, cylindrical shape, comprising a plurality of superimposed layers of a having a continuous strip of magnetic material. The invention also relates to a method to make this coil.

When making induction coils with cores of magnetic material, usually iron, special Attention should be paid to the magnetic properties of iron, as these are related to the The strength of the magnetizing field and the size of the air gap vary considerably, if one is provided is. In many applications it is necessary to use an air gap as this can cause changes in inductance with changes in current through the Coil reduced. So it can be said that the air gap extends the closed magnetic circuit. this but occurs with a multiplication factor, whichever Ranges from 100 to 1000, which means that the size of the air gap has a completely determining influence has on the properties of the induction coil.

In the case of, inter alia, toroidal induction coils, which are highly advantageous in many ways it has been found that it is very difficult to find small air gaps of precisely predetermined size

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to create, due to the elasticity of the magnetic material. US Pat. No. 1,318,787 describes a method for solving this problem, wherein the iron core consists of a plurality of annular elements which are axially perforated by slots which are defined in the radial direction by ^: '*;' at least one uninterrupted part are delimited, * .... * which serves to hold the annular element together. - .. * - ·

Nowadays the manufacture of iron cores ^

achieved by winding a continuous strip of '..'. '' onto a spindle until the desired core: ..,:. thickness is reached. If the method of the aforementioned US patent were used, all turns of the core, except perhaps the last turn, would be cut out entirely. Because of the elasticity of the strip material, this would mean that deformation forces exerted by the inner turns would act on the outer turn. Furthermore, the possibility cannot be excluded that the ends of the cut-out turns shift, which would mean that the width of the air gap would vary slightly from turn to turn.

As there are no acceptable options for manufacture a precisely determined air gap in ring-shaped iron cores, which is used for high quality purposes are determined, the cores nowadays usually have the shape of so-called C-cores, welehe are combined in pairs, with an air gap in between, or in the form

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a combination of Ε-kernels and I-kernels, where an air gap is normally formed between the mid-leg of the Ε-core and the I-core.

To create a core for applications where If an induction coil of precise toroidal shape is desired, it is necessary to have the core first embedded in a plastic material and then sawed the core. As can be understood, this requires an additional work step, which makes the core more expensive and the scope of the process limited.

As a result of the multiplication factor from 100 to 1000, the variation in the length of the air gap has one great effect on the characteristics of the induction coil. So caused z. B. a change in the air gap from 0.5 to 0.6 mm a 20% extension of this, which is due to the high multiplication factor in an even greater change in the characteristics of the induction coil results. That's why it was so far It is common to use relatively wide gaps where small differences are not comparable in size Cause effects in proportion.

The main object of the present invention is to provide an induction coil of the type mentioned at the beginning create that can be provided with a narrow and well-defined air gap.

This object is achieved according to the invention by providing the core with perforations or slots that extending radially through the core, and which axially in each layer of the core by at least

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are bounded by an uninterrupted portion which holds the layer together. That means that the inner Layers do not exert any force on the outer layers, as each layer is at least one uninterrupted Has material tongue, which the respective layer

holds together. Preferably the area is uninterrupted Part or the continuous parts in each layer so that the part or parts below the Desired operating conditions of the induction coil -JO is or are saturated, since they in this way the have the same effect as if they also contained air.

A method according to the invention for producing a: Induction coil in which the core is formed by winding a large number of overlapping layers produced from a continuous strip of magnetic material on a spindle is thereby characterized in that the perforations or slits either before or when the strip is wound up the spindle punched in the strip in the way will be that the openings face each other when the strip is wound, or alternatively by boring the core radially or otherwise cutting the strip when the core is finished winding is. If the perforations are created by radially drilling the core, the dimensions of the air gap can be progressively adjusted while the properties of the core are measured.

The strip can be punched during winding with the help of a punching tool, which depends on from the winding length of the strip on the spindle or alternatively by a control strip is controlled.

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In the following, exemplary embodiments of the invention are described in detail with reference on the attached drawings. Show it:

1 shows a plan view of an annular throttle core according to the invention;

Figure 2 is a cross-sectional view of the core of Figure 1 along the line II-II;

3 shows part of the strip of magnetic material which is used in the manufacture of the reactor core of Figures 1 and 2 is used;

4 shows an alternative embodiment of a strip intended for a magnetic core;

Fig. 5 shows a further embodiment of a strip intended for a choke coil core;

6 is a cross-sectional view of an annular

Choke coil which has an iron core and is made from a strip as shown in FIG is.

The reactor core of Figs. 1 and 2 was made by winding a strip sheet 1 of the embodiment obtained according to Fig. 3 on a spindle, the spindle leaving a cavity 2 when pulled out, which can be used for the subsequent winding of the actual choke coil. For the purpose of creating the desired air gaps, the strip 1 was punched to provide pairs of slots 3, which when winding the strip on the

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Spindle are arranged opposite one another. The distances a, b and c therefore correspond to the circumference of successive strip windings. Between the slits 3 of each pair there is an uninterrupted part 4 which holds the strip together and enables the strip to be wound up. Thus, each winding is determined using the ^{uninterruptedly:} held together rupted part and consequently by no ^contact: ne spring back tendencies, the size of the air gap

could influence. Furthermore, the inner wraps practice no deformation force applied only to the external; Winding or windings.

The strip 1 'of FIG. 4 differs from the strip 1 of FIG. 3 in that the strip 1 ^{1 is provided} with an elongated, continuous slot 3', an uninterrupted part 4 ^{1 being arranged} at each end of the respective slot . Part 4 'fulfills the same function as part 4 in strip 1 of FIG. 3. Preferably, the dimensions of the parts are such that they are saturated under the desired working conditions of the choke coil. This means that the continuous parts are also given air gap properties. The slots of Figures 3 and 4 are only preferred embodiments as these slots can be varied as desired, both in number and in shape. It is important, however, that at least one continuous portion be obtained to hold the strip together in each turn.

The slots can either be made with the help of a one-piece punching tool before winding the strip or while the strip is being wound up be punched, whereby the punching process of the

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fens is controlled either by the winding length or with the help of a control strip. The inductor core can also be wound from a continuous strip and then the desired air gap by drilling, sawing or other cutting operation. In this case you can the properties of the core are measured continuously during the manufacturing process of the core, so as to to get the desired characteristics.

With the help of the method described above, it is possible to produce inductor cores with extremely small air gaps, on the order of 0.5 well, with great precision, i.e. H. with an accuracy of about 5/100 mm.

Fig. 5 shows part of a so-called wedge-shaped clipping of a sheet material, which forms a strip 11 which is provided with slots 13 in accordance with the aforesaid is provided by punching, the slots being arranged opposite one another when the strip is wound on the spindle. As a result of the wedge shape of the strip, when the strip is wound up received on a spindle a core which has a parallelogram-shaped cross-section, the Core makes it possible to wind a choke coil with an essentially flat upper and lower surface. At the Winding the choke coil, the number of winding layers inside the choke coil at 16 is greater when it is at 17 on the outer surface. So the number of turns at the ends of the inductor decreases inner part 16 to outer part 17, as indicated at 15.

Such a choke coil shape enables, among other things, that the choke coil in a much simpler Shape can be encapsulated because the inductor z. B. in a pot. Like. Be housed can, whereby only little space has to be filled with filler material. Furthermore, such a figure creates good heat distribution properties as a result of the flat mounting surfaces, which are used as cooling surfaces "<_ ken. If only one flat plane is provided, the core can be given a rhombic cross-sectional shape. · * ' The invention can also be modified in other respects within the scope of the following claims.

Claims (6)

3049381 Claims Jy induction coil with a core in the form of a closed loop, specifically of circular cylindrical shape, which has a plurality of one:. of the overlying layers of a continuous strip (1, 1 ¹ , 11) of magnetic material, characterized in that the core is provided with * openings or slots (3, 3 ', 13) *' which extend radially in order to achieve air gap properties extend through the core, the perforation or slits (3, 3 ', 13) in each layer' is at least uninterruptedly '*>' rupted part (4, 4 *) are limited, wherein cohesion in the axial direction by a layer. 2. Induction coil according to claim 1, characterized in that the uninterrupted parts (4, 4 ¹ ) of each layer have such an area that these parts are saturated under the desired operating conditions of the induction coil. 3. Method of making an induction coil with a core in the form of a closed loop, specifically of circular cylindrical shape in which the core is formed by winding a continuous strip made of magnetic material on a spindle by a number of turns corresponding to the desired core thickness will be produced, characterized in that, in order to obtain air gap properties, the core is radially with it perforations or slots extending through the core are provided, the perforations or slots 304998 in each layer by at least one interrupted part, which holds the layer together, in the axial direction be limited, either before or when winding the strip onto the spindle openings in the strip are punched in such a way that the openings face each other when the strip is wound, or alternate radial holes are drilled in the finished wound core or in some other way cut into the core. 4. The method according to claim 3, characterized in that the punching or drilling over such a part of the strip width is carried out that the remaining material tongue or tongues have such an area that the tongue or tongues is saturated under the desired operating conditions or are. 5. The method according to claim 3 or 4, characterized in that the strip during the winding up of the core is punched out with the help of a punching tool, which depends on the winding length of the strip on the spindle is controlled. 6. The method according to claim 3 or 4, characterized in that the strip during the Aufwickeins the core is punched out with the help of a punching tool, which is through a control strip is controlled.