EP1898494B1 - Method for manufacturing a magnet assembly with a flat magnet core and such a magnet assembly - Google Patents

Description

The invention relates to a method for producing a magnet assembly with a wound flat magnetic core, and a support body for use in this method.

Such magnet arrangements have a magnetic core which carries a conductor winding and can have a high quality, which is interesting for a frequency range from 1 kHz to about 20 MHz and above. For example, the magnet arrangements can serve as antenna rods in RFID (Radio Frequency Identification) systems, anti-theft devices, recognition systems, for wireless energy transmission, for example for recharging accumulators, as well as for information transmission. Typical operating frequencies in these applications are approximately 20 to 150 kHz or 13.5 MHz.

A corresponding magnetic core is flat and strip-shaped, wherein the thickness is much smaller than the width and this in turn is much smaller than the length of the magnet arrangement or the magnetic core. Typical thicknesses range from fractions of millimeters to a few millimeters, the width is for example between 2 and 30 millimeters and the length is about 10 to 150 millimeters.

As a material for the corresponding magnetic cores on the one hand, ferrites in question, on the other hand, however, also laminated thin strips of amorphous or nanocrystalline magnetic material. Nanocrystalline or amorphous materials have the advantage of high saturation magnetization and, as a laminate, high flexibility and mechanical insensitivity.

The winding is carried out as a toroidal coil around the core, with the longitudinal axis of the core and toroid coinciding. The winding numbers are typically 10-1000. In many cases, particularly flat cores or magnet arrangements desired, for example, with a total thickness of the magnet assembly in the range of one to a few millimeters. The minimum achievable thickness of the magnet arrangement is composed of the sum of two winding layers (above and below the magnetic core) and the thickness of the magnet core. In particularly flat designs, the problem arises that a very thin magnetic core with a thin insulated conductor as possible must be tight and tight wound. Dodging on strip-shaped ladder, z. B. flat wire or foil is not possible for a given required winding density and conductor cross-section for lack of space. Thus, there is the danger that the insulation of the winding conductor during winding or even later during operation is damaged, in particular in the case of electrically conductive magnetic cores, which leads to short-circuits which severely impair the functioning of the magnet arrangement.

Although this problem could be overcome, there is the added problem that, during winding, the winding conductor must be wound quite tightly onto the magnetic core so that it has undesirable lateral forces acting on it during winding, which deform it. This makes reliable winding virtually impossible without the risk of damage and with the desired accuracy.

Flat magnetic cores, which consist of laminated ribbons of amorphous magnetic alloys are, for example, from DE 195 13 607 for various applications, for example, for installation in EC cards, known. From the EP 0 762 535 are also correspondingly flat laminated designs with a Leiterbewicklung known. From the US 6,921,042 are skewed cores known. EP 1 037 304 A and DE 101 03 068 C1 reveal cores wound together with a carrier.

The object of the invention is therefore a method for producing a magnet arrangement with a flat magnetic core, whose width is greater than its height, and specify with a coil-shaped winding of at least one conductor, in which the magnet assembly without the risk of damage to the winding or the magnetic core is to be made as flat as possible.

The object is achieved by a method according to claim 1 and a support body according to claim 14.

It is a magnetic core with an insulated round wire, for example, has a diameter between 0.1 and 0.4 mm wound, the thickness of the magnetic core can be between 0.1 and 1 millimeter. The magnetic core is clamped in a winding machine and rotated about the longitudinal axis for winding. In this case, a certain minimum tensile force is exerted on the winding conductor in order to achieve a tight contact with the magnetic core. In order to stabilize the magnetic core during the winding process, without unnecessarily increasing its subsequent height, it is provided to support the magnetic core by a support body during winding with the conductor and to remove the support body after winding.

In this case, the support body, for example, wound together with the magnetic core and then pulled out of the winding. The parts of the individual turns of the winding projecting freely beyond the magnet core after extraction of the support body are advantageously folded in the longitudinal direction, ie in the direction of the coil longitudinal axis or the magnetic core longitudinal axis, against the magnet core with a pivoting movement and fastened there, for example, by means of an adhesive.

In the method, a support body is advantageously used, which corresponds in width to the dimensions of the magnetic core, wherein the length of the support body may be greater than that of the magnetic core to facilitate a simple clamping in a winding machine. It will be that way, then ensures that during the winding process, the magnetic core is stabilized without the height of the magnet assembly increases. The problem of the extended turns can then be solved as described by folding the windings to the magnetic core.

If, in addition, the risk of injury to the winding conductor insulation at the edges of the magnetic core is to be reduced, provision may also be made for the supporting body to protrude beyond the magnet core with respect to the width.

The support body can then also have a U-shaped contour in cross-section, so that it encloses the magnetic core in a trough-shaped manner on at least one side and thus prevents contact of the winding conductor at least on this side of the magnetic core. The outer contours of the support body may be rounded so that there is no risk of injury to the winding conductor.

The support body may also have on the underside facing away from the magnetic core an elevated and extending in the longitudinal direction of the magnetic core web. This provides for increased stability of the assembly and may be hinged or otherwise removable to facilitate removal of the support body from the finished wound coil, for example to the support body.

It may also be advantageous if the support body after winding and before its removal from the magnetic body by external action with respect to its height and / or width can be reduced. This can be realized, for example, in that the support body is folded or pushed together after winding.

After pulling the support body out of the winding, the turns either in segments in the same direction or in different directions parallel to the longitudinal axis of the magnetic core folded at this. In this case, an adhesive can be applied at the same time to fix the windings or a double-sided adhesive tape can be used to fix the folded turn parts on the magnetic core.

As a result of the entire manufacturing process, a magnet arrangement has a flat magnetic core whose width is greater than its height and whose length is substantially greater than its width, and a coil-shaped winding having a winding conductor, wherein the turns of the conductor are at least 30% of the thickness of the magnetic core (corresponds to twice the minimum thickness of the support body) are longer than the smallest possible spiral winding of the magnetic core corresponds and wherein the winding parts per turn on the top and bottom of the magnetic core against each other in the direction of the longitudinal axis of the magnetic core abut this.

The magnetic properties of the arrangement are not affected by the described design of the winding. The magnet assembly, if the core is a laminate of various only a few microns thick amorphous or nanocrystalline magnetic materials, highly flexible, without this would adversely affect during the manufacturing process. Due to the anisotropy of the laminated core, the change in the shape of the winding also does not practically affect the direction of the magnetization. This arrangement is particularly advantageous when the magnetic core is less than 2 millimeters thick. It is even more advantageous if the magnetic core is less than 1 millimeter thick.

The invention further relates to a support body for use in the method described above, the support body can be designed as a so-called coincident construction, for example, consisting of two sub-bodies, which after winding against each other so be be swept that reduce the effective height and / or width of the support body and the support body or its items can be easily removed.

It can also be provided to produce the support body from a material having a so-called temperature memory, such that the support body at a first temperature, when joined together with the magnetic core, takes up more space than at a second temperature. The winding then takes place at the first temperature, then the temperature is changed to the second temperature and pulled out the support body.

Figur 1

einen beim Bewickeln verformten Magnetkern,

Figur 2

einen durch einen Stützkörper stabilisierten Magnetkern,

Figur 3

einen Magnetkern mit einem Stützkörper in einer Draufsicht,

Figur 4

das Abziehen eines Stützkörpers von einem Magnetkern,

Figur 5

das Abklappen verschiedener Wicklungsteile auf einen Magnetkern zu verschiedenen Richtungen,

Figur 6

schematisch einen Magnetkern mit zwei Windungen zur Verdeutlichung der Maße und Winkel,

Figur 7

schematisch einen Stützkörper, der aus mehreren Teilen besteht und bezüglich der Breite verkleinert werden kann,

Figur 8

einen Stützkörper wie in Figur 7 im Querschnitt,

Figur 9

einen Magnetkern mit einem Stützkörper in Draufsicht,

Figur 10

die Konstellation wie in Figur 9 im Längsschnitt,

Figur 11

einen Magnetkern und einen Stützkörper im Querschnitt,

Figur 12

die Konstellation aus Figur 11 nach Verformung des Stützkörpersund

Figur 13

einen Magnetkern und einen Stützkörper im Querschnitt.

The invention will be explained with reference to embodiments illustrated in the figures of the drawing. It shows:

FIG. 1

a deformed during winding magnetic core,

FIG. 2

a magnetic core stabilized by a support body,

FIG. 3

a magnetic core with a supporting body in a plan view,

FIG. 4

the removal of a support body from a magnetic core,

FIG. 5

the folding of different winding parts on a magnetic core to different directions,

FIG. 6

schematically a magnetic core with two turns to illustrate the dimensions and angles,

FIG. 7

schematically a support body, which consists of several parts and can be reduced in width,

FIG. 8

a supporting body as in FIG. 7 in cross section,

FIG. 9

a magnetic core with a supporting body in plan view,

FIG. 10

the constellation as in FIG. 9 in longitudinal section,

FIG. 11

a magnetic core and a support body in cross section,

FIG. 12

the constellation FIG. 11 after deformation of the support body and

FIG. 13

a magnetic core and a supporting body in cross section.

FIG. 1 shows a magnetic core 1, on which a winding 2 is wound. This is done by the magnetic body 1, as indicated by the arrow 3, is rotated about its longitudinal axis. He is to rotatably mounted in two camps 4, 5. During the winding of the magnetic core, a tensile force is exerted on the conductor 6 of the winding 2 in the direction of the arrow F in order to achieve a tight-fitting winding. By this force, the magnetic body 1 is simultaneously deformed in the direction of the force F, so that it bends during its rotation in this direction. This damages the stability of the magnetic core and can lead to its destruction.

FIG. 2 shows the magnetic body 1, which is supported by a support body 7. The support body 7 consists of two parts, a base body 8 and a connection body 9, whereby the support body after the application of the winding 10 are more easily pulled out of this and the connection body 9 can be separated from the support body. However, a one-piece design of the support body is also possible, but worse to pull out at longer windings. It can also additional fasteners for the core are provided on the support body, these are not shown in the drawing for the sake of simplicity. The support body 7 is rotatably clamped in bearings at its two ends 11, 12, so that the magnet body 1 and the support body 7 can rotate together about a longitudinal axis 13 for applying the winding 10.

The FIG. 3 shows in a plan view of a support body 7, which protrudes slightly with respect to the width B over the magnetic core 1, to prevent contact with the conductor during the winding with the lower edges of the magnetic core. However, the width of the support body 7 can also coincide exactly with the width of the magnetic core 1 when required.

The FIG. 4 shows a support body 7 and a part 8 of the support body, which has been pulled out in the direction of arrow 14 from the winding 10, so that now parts 15, 16 project from turns of the winding 10 via the magnetic core 1 down.

In the FIG. 5 It is shown that the segments 17, 18 of the winding 10 have been treated differently. The protruding parts of the turns of the segment 17 of the winding 10 are in the direction of the arrow 19, the turns of the segment 18 of the winding 10 are folded in the direction of the arrow 20 to the magnetic core 1 by pivoting and fixed there by means of an adhesive.

It is also conceivable that even more segments are formed with different Abklapprichtungen. In principle, however, all windings of the windings can be folded to the same side in the longitudinal or axial direction of the magnetic core 1.

Based on FIG. 6 The different dimensions of the windings, the magnetic core and the support body can be related to each other. First, in the drawing, the height of the magnetic core, w the height of the support body, d the diameter of the winding conductor, b the distance of the turns on the surface of the magnetic core, x the distance of the turns perpendicular to their course on the narrow sides of the magnetic core and γ the angle between the longitudinal axis 13 of the magnetic core and the turns of the winding in the region of the narrow sides of the magnetic core. $$\mathrm{It\; applies}:\mathrm{x}=\left(\left(\mathrm{b}+\mathrm{d}\right)\cdot \left(\mathrm{a}+\mathrm{d}\right)\right)/\left(\mathrm{a}+\mathrm{w}+\mathrm{d}\right))-\mathrm{d}$$

A complete tilting of the turns until resting on the bottom and top of the magnetic core is only possible if the distance b between two turns on the surface of the magnetic core is sufficiently large. The minimum value for b is when x = 0 is set: $$\mathrm{b}=\mathrm{w}/\left(\left(\mathrm{a}/\mathrm{<figure-callout\; id="1"\; label="d\; +"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d\; </figure-callout>}\right)+\mathrm{1}\right)$$

The angle γ, which include the oblique parts of the turns with the longitudinal axis 13 of the magnetic core, may be less than 70 °. As a result, the symmetry axis of each individual turn is no longer parallel to the longitudinal axis of the magnetic core. The effect is, however, justifiable, even for ferrite cores. Under these conditions, laminated cores having a shape anisotropy in the direction of the longitudinal axis and material permeabilities of more than 1000 behave particularly advantageously, because in them the magnetization is conducted into the tape layers of the laminate, so that the skew of the windings has virtually no influence on the direction the magnetization has. It is important that the lamination of the laminate runs along the width and length of the magnetic core as in FIG. 5 rudimentary.

FIG. 7 shows a support body, which consists of two part bodies 21, 22 which are wedge-shaped in plan view. In order to reduce the width of the support body 21, 22, the first part body 21 is moved in the direction of the arrow 23 and the second part body 22 in the direction of the arrow 24. In order to achieve a reliable guidance of the two body parts to each other, they are in the area in which they rest against each other, by means of a web and a groove, as in FIG. 8 shown, adapted to each other. As a result, a reduction of the width and thus the extraction of the support body from the winding is reliably possible after the application of the winding.

Another variant shows the FIG. 9 in a plan view and the FIG. 10 in a longitudinal section. There, each of the magnetic core 1 is shown together with a first part body 25 and a second part body 26, which also fit together in a wedge shape, but in the longitudinal sectional plane, as in FIG. 10 is shown. These partial bodies can also be pulled apart after the application of the winding in the direction of the arrows 27, 28 to reduce the height of the support body.

In the FIG. 11 is shown in cross-section a support body 29 which supports the magnetic core 1 for applying the winding. After applying the winding, the temperature of the constellation is changed. The support body 29 is made of a material having a so-called temperature memory, so that the body automatically assumes different shapes at different temperatures. The support body 29 then takes up the winding and at the second temperature in the FIG. 12 shown in cross-section, so that the overall height of the arrangement is reduced and the support body 29 can be easily pulled out in the longitudinal direction of the magnetic core 1 from the winding.

FIG. 13 shows a magnetic core 1 with a two-part support body 30, 31, wherein the first part of body 30 of the support body in cross section has a U-shape, wherein the individual legs of the U-shape in cross section in the direction of Width of the magnetic core 1 run. Between the legs of the first part body 30 is a gap in which the second part body 31 is partially immersed. The two partial bodies 30, 31 together have approximately the width of the magnetic core and can be fixed in this constellation against each other, for example by means of a screw.

After the winding has been applied to the magnetic core 1 and the support body 30, 31, the fixation can be solved and the second part body 31 can be further inserted into the first part body 30, so that the width of the constellation of the support body decreases and this the winding can be easily pulled out.

The invention thus provides an easy-to-use method for producing a magnet arrangement in which the magnetic core itself is subjected to as little mechanical stress as possible during winding without the quality of the winding suffering thereunder and in which the magnet arrangement has a minimal volume.

Claims (14)

1. A method for manufacturing a magnet arrangement with a flat magnet core (1) the width of which is greater than height of which, in which the magnet core (1) is supported during the winding with a conductor by a supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31), characterized in that, after the winding, the supporting body is removed and thereafter the coil (2, 10) is pressed on until it is in contact with the two flat sides of the magnet core.
2. The method according to claim 1, in which the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31) is wound jointly with the magnet core (1).
3. The method according to claim 1 or 2, in which the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31) has the same width as the magnet core (1).
4. The method according to claim 2, in which the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31) has a greater width than the magnet core (1).
5. The method according to any one of claims 1 to 4, in which the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31) at least partially covers the small sides of the magnet core (1).
6. The method according to any one of claims 1 to 5, in which the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31) is U-shaped in cross section.
7. The method according to any one of claims 2 to 6, in which the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31), on the underside thereof facing away from the magnet core (1), comprises an elevated web extending in longitudinal direction of the magnet core.
8. The method according to any one of claims 2 to 7, in which, after the winding and before the removal thereof, the supporting body (7, 8, 9, 21, 22, 25, 26, 29, 30, 31) is reduced in size in terms of the height and/or width thereof by an external action.
9. The method according to claim 8, in which, after the winding, a supporting body (21, 22, 25, 26, 30, 31) constructed in several parts in the manner of a collapsing construction is folded up or telescoped.
10. The method according to any one of claims 2 to 9, in which, after the removal of the supporting body, the winding portions (15, 16) protruding over the magnet core (1) are swivelled in the direction of the core longitudinal axis (13) onto the magnet core (1).
11. The method according to claim 10, in which all the longitudinal sections (17, 18) of the winding (2, 10) are swivelled in the same direction.
12. The method according to claim 10, in which different longitudinal sections (17, 18) of the winding (2, 10) are swivelled in opposite directions.
13. The method according to claim 10, 11 or 12, in which, after the swivelling of the winding portions of the magnet core (1), said winding portions are fastened by means of an adhesive to the magnet core (1).
14. A supporting body which is adapted for use in the method according to any one of claims 1 to 13, characterized by a first partial body (30) which is U-shaped in cross section, between the arms of which a second partial body (31) is insertable, until the two partial bodies together in cross section have an expansion in longitudinal direction of the arms of the U shape, which corresponds at least to the width of the magnet core (1), wherein the two partial bodies (30, 31) can be detachably fastened against one another, and wherein the second partial body (31) is insertable between the arms of the first partial body (30), until the expansion of the supporting body in cross section is reducible in longitudinal direction of the arms to a size less than the width of the magnet core.

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