WO2018014141A1

WO2018014141A1 - Segmented permanent magnets

Info

Publication number: WO2018014141A1
Application number: PCT/CH2016/000105
Authority: WO
Inventors: Kurt Weber
Original assignee: Bomatec Holding Ag
Priority date: 2016-07-18
Filing date: 2016-07-18
Publication date: 2018-01-25

Abstract

The invention relates to a segmented permanent magnet comprising at least two permanent magnet segments (1) which are connected to one another by means of at least one adhesive layer (2). The adhesive layer (1) consists at least partially of a thermosetting plastic matrix having fiber reinforcement (2a), also known as a "prepreg". This enables a simplified production of the segmented permanent magnet.

Description

Segmented permanent magnets

Field of the Invention The invention relates to a segmented one

Permanent magnet according to the preamble of claim 1, comprising at least two permanent magnet segments, which are interconnected via at least one adhesive layer.

background

Permanent magnet motors, especially motors with high speeds, are light and efficient drives, which have permanent magnets. To reduce eddy current losses that occur during operation, the permanent magnets are segmented. An adhesive is in each case arranged between the permanent magnet segments in order to hold the permanent magnet segments together to form a segmented permanent magnet and also to mutually isolate the individual permanent magnet segments in order to reduce the eddy current losses.

The bonding of permanent magnet segments with a liquid adhesive is extremely difficult, because the adhesive must be applied evenly to ensure an adhesive effect on the entire contact surface. Otherwise, the permanent magnet segments tear under load on the splice and destroy the drive. Furthermore, after adhesive bonding of the permanent magnet segments, excess adhesive must be removed, which leads to a complex manufacturing process. Furthermore, it is extremely important that the magnet packages have absolutely the same mass and weights to prevent imbalance.

Presentation of the invention It is therefore the object to provide a segmented permanent magnet, which is easy to produce.

This object is achieved by the segmented permanent magnet according to claim 1.

Accordingly, the segmented permanent magnet on at least two permanent magnet segments, which are connected to each other via at least one adhesive layer. The at least one adhesive layer consists at least partially of a thermosetting plastic matrix with fiber reinforcement.

Advantageously, the entire adhesive layer consists of a thermosetting plastic matrix with fiber reinforcement.

Alternatively, the thermoset material ^¬ matrix with fiber reinforcement is also called "prepreg" for "preimpregnated fibers".

As permanent magnet segments, individual parts are understood to be those which are known to a person skilled in the art and are permanently magnetizable, and in particular conductive, (for example SmCo magnets or NeFeB magnets) which can be joined together to form a magnet made of the permanent magnet material.

The permanent magnet segments can have any desired geometry, wherein the individual permanent magnet segments of a segmented permanent magnet can have different geometries.

Advantageously, the Kunststoffmar rix consist of epoxy resin. Such epoxy adhesives are known in the art.

A durop] astic plastic matrix with fiber reinforcement has the advantage that it is a solid layer, such as a mat, which can be pre-cut to size and easily positioned and placed at the bond site. In contrast, liquid glue is not easy to apply and it is difficult to produce a uniformly thick adhesive layer.

Another advantage is that the segmented permanent magnet can be pressed together in a controlled manner. This is desirable because the permanent magnet segments have different thicknesses due to manufacturing inaccuracies and the entire segmented permanent magnet having a plurality of permanent magnet segments therefore does not have the desired length or height from the outset. After the permanent magnet segments and the K1ebeschichten were stacked in the Herstellungsprozes s, the entire segmented permanent magnet with its different thickness permanent magnet segments can be pressed to a predefined length or height by the adhesive layers are compressed and the existing in the adhesive layer plastic expands.

In contrast, in the case of a liquid adhesive, the segmented permanent magnet can not be pressed so easily because there is no fiber reinforcement, which ensures a uniform compression of the adhesive layer or a uniform reduction of the adhesive layer thickness. That If adhesive layers of liquid adhesive are pressed together, there would be a risk that at certain points of the adhesive layer, the adhesive would completely escape and these defects would weaken the adhesive bond and, at the same time, cause metallic contact between the permanent magnet segments. In contrast, the fiber reinforcement results in a more stable adhesive layer so that it can be easily pressed without weakening the adhesive effect.

A further advantage is that the adhesive layer, before insertion in the segmented permanent magnet, to a desired thickness, length and

Width can be precut, so that a clearly defi ^¬ ned amount of adhesive layer is present. Furthermore, the fiber reinforcement is advantageously designed as an endless fiber reinforcement.

This leads to a more stable fiber reinforcement because the fibers run continuously through the adhesive layer.

Furthermore, the fiber reinforcement may be in the form of an unidirectional layer and / or as a multidirectional layer

Layer and / or designed as a fabric and / or knitted fabric. In particular, the fiber reinforcement may have a plurality of fiber layers, in particular a plurality of fabric layers.

With optimal choice of fiber high forces can be absorbed. With unidirectional fiber reinforcement, the fibers are mostly in the same direction. In multidirectional fiber reinforcement, the fibers run in different directions. For example, two superimposed fiber layers may be aligned in directions rotated by 90 ° with respect to each other. This is a bidirectional layer. In a fabric, the fibers are crossed, with one passing through fibers at a particular rhythm above and below the transverse fibers. In a knitted fabric fibers are partially configured as stitches.

Advantageously, at least two permanent magnet segments are glued to one another via adhesive contact surfaces of the permanent magnet segments and via an adhesive layer in such a way that the one adhesive layer is arranged between the Kiebe contact surfaces.

The adhesive contact surfaces are those outer surfaces of permanent magnet segments which are in contact with an adhesive layer. The adhesive contact surface is not necessarily completely in contact with the adhesive layer. The limit of the adhesive pushes clockwise is defined geometrically and not depending on the presence of the adhesive layer. In a cuboid permanent magnet segment For example, the adhesive contact surfaces are limited by the edges of the cuboid.

For example, the adhesive layer lies between the adhesive contact surfaces when identically dimensioned, parallelepiped-shaped permanent magnet gravities are linearly stacked on one another. In this case, upper and lower sides of the cuboid permanent magnet segments form the adhesive contact surfaces between which the adhesive layers are arranged.

Furthermore, the adhesive layer may extend only over part of the adhesive contact surfaces. In particular, an edge region of the adhesive contact surfaces is free of the adhesive layer, in particular wherein the edge region is free of the adhesive layer over an entire circumference of the adhesive contact surfaces, in particular wherein the edge region has a width of 0.5 mm to 1 mm.

The width of the edge region is to be understood as the distance which extends normally from the edge of the adhesive contact surface into the interior of the adhesive contact surface.

The release of the edge region has the advantage that the adhesive layer does not go beyond the edge of the adhesive contact surfaces during the manufacturing process by pressing. Although so that the adhesive layer does not extend to the edge of the adhesive contact surface, a good adhesive effect can still be ensured and the insulation between the permanent magnet segments is also not affected because the intervening air also acts insulating.

It is advantageous if the permanent magnet segments are additionally connected to one another in such a way that one of the at least one adhesive layer is arranged on outer surfaces of the permanent magnet segments which are normally arranged on the adhesive contact surfaces of the intermediate adhesive layer. Such an additional adhesive layer leads to an even better stability of the segmented permanent magnet.

The permanent magnet segments advantageously have no surface coating, in particular of resin.

In the bonded state, the adhesive layer may have a thickness of less than 0.07 mm, in particular less than 0.05 mm, in particular less than 0.04 mm, in particular less than 0.03 mm.

This allows a high magnetic content of the segmented permanent magnet and thus a higher magnetic density.

Furthermore, the object is to provide a method with which segmented permanent magnets can be easily produced.

This object is achieved by the process for the preparation of a segmented permanent magnet according to ^¬ demanding. 9

Accordingly, the method includes the following

Manufacturing steps:

- From a magnetizable, in particular electrically conductive, existing material or a magnetizable material comprehensive permanent magnet sec- ments are stacked on top of each other. At least one adhesive layer is inserted between the permanent magnet segments ge ^¬ sets, wherein the adhesive layer consists of a thermosetting plastic matrix is fiber reinforced.

- are layers The permanent magnet segments and the adhesive hot-pressed to a segmented permanent magnets, wherein the plastic matrix ver ^¬ liquefied itself, in particular at a temperature higher than 140 ° C, in particular higher than 160 ° C, in particular higher than 180 ° C;

- In a further step, the material of the permanent magnet is magnetized, warm or cold. This method has the advantage that, by interposing the fiber-reinforced adhesive layers, hot pressing can take place in a controlled manner. There is a controllable amount of adhesive layer which can be easily compressed due to the fiber reinforcement.

Advantageously, in hot pressing, the pressing pressure is selected such that the segmented permanent magnet is pressed to a predetermined length or height.

As a result, the desired length or height of the segmented permanent magnet can be precisely adjusted by compensating for the different permanent magnet segment thicknesses due to manufacturing inaccuracies by compressing the adhesive layers. That If, on the fly, the permanent magnet segments have on average become too thick during production, then the adhesive layers are pressed together by hot pressing so that thin adhesive layer thicknesses can compensate for the large permanent magnet segment thicknesses and the desired length or height of the segmented permanent magnets can be achieved. On the other hand, if the permanent magnet segments have been made too thin on average, for example, then the adhesive layers are less compressed.

Advantageously, the at least one adhesive layer prior to the hot pressing ^¬ a thickness of less than 0.7 mm, in particular less than 0.5 mm, in particular we ^¬ niger than 0.4 mm, in particular less than 0.3 mm on.

The thickness of the adhesive layer is selected prior to hot pressing so that it can be reduced during the hot press.

Furthermore, after the hot pressing, the segmented permanent magnet can be cut by wire erosion, by means of a diamond disk, by means of a diamond thread or with a water jet. Advantageously, two of the permanent magnet segments are glued to each other via adhesive contact surfaces of the permanent magnet segments and via one of the at least one adhesive layer. In this case, one of the at least one adhesive layer is interposed before the hot pressing, wherein the adhesive layer does not extend over the entire adhesive contact surfaces of the permanent magnet segments, so that the adhesive layer does not exceed the adhesive contact surfaces by the hot pressing.

Due to the reduced area of the adhesive layer, a further method step can be avoided, in which the residues of the adhesive layer that have gone out through hot pressing need not be removed.

This simplifies the manufacturing process.

Brief description of the drawings

Further embodiments, advantages and applications of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

1 shows a segmented permanent magnet with five cuboid permanent magnet segments.

FIG. 2 shows a segmented permanent magnet with an additional lateral adhesive layer; FIG.

3 shows two segmented permanent magnets of the same length with different lengths of permanent magnet segments;

4 shows the hot pressing process of the segmented permanent magnet; and

Fig. 5 shows a section through a segmented permanent magnet before the hot pressing process.

Way to carry out the invention In Fig. 1, a segmented permanent magnet is shown. It has five cuboid permanent magnet segments 1, which are glued together by adhesive layers 2. The adhesive layer consists of a thermosetting plastic matrix with fiber reinforcement 2a. The fiber reinforcement 2a consists for example of continuous fibers, which are arranged as a fabric. The permanent magnet segments 1 are in contact via the adhesive contact surfaces 3 with the adhesive layer 2.

The adhesive layer 2 in this case has a multilayer fiber reinforcement 2a.

In the present example, the underside forms 4 of a cuboid permanent magnet segment

1 the one adhesive contact surface 3, while the upper side 5 of the other cuboid permanent magnet segment 1 forms the other adhesive contact surface 3. The adhesive contact surface 3 is, by definition, the area of the permanent magnet segment 1 which is in contact with the adhesive layer 2. However, the adhesive contact surface 3 is not in its surface by the adhesive layer

2 limited, but by the geometric edges of the adhesive contact surface 3 of the cuboid permanent magnet segment. 1

That On the one hand, in the present example, the underside 3 and the upper side 5 of the parallelepiped-shaped permanent magnet segment are identical to the adhesive contact surface 3 and, on the other hand, an edge region 6 results on the adhesive contact surface 3, which is not in contact with the adhesive layer 1.

2, a segmented permanent magnet is shown, which is additionally glued to a side adhesive layer 7. This lateral adhesive layer 7 is arranged on outer surfaces 8 arranged normally to the adhesive contact surfaces 3 of the intermediate adhesive layer 2. These outer surfaces 8 are thus also adhesive contact surfaces. However, these are normal to those adhesive contact surfaces 3, which are in contact with the adhesive layers 2, which are arranged between two adhesive contact surfaces 3.

The adhesive layer 7 is not arranged between adhesive contact surfaces, but it is only on one side with the adhesive contact surfaces 8 in contact.

In Fig. 3, two equal-length, segmented permanent magnets (a) and (b) are shown, which have different thickness permanent magnet segments 1 and different thicknesses adhesive layers 2. In the segmented permanent (a), the permanent magnet segments 1 are thicker and the adhesive layers 2 thinner compared to the segmented permanent magnet (b),

This comparison illustrates a significant advantage through the use of a thermosetting plastic matrix with fiber reinforcement as the adhesive layer 2. Namely, the primary manufacturing goal is that the segmented permanent magnet has a predefined length 9. However, this is not easy to achieve, since the permanent magnet segments 1 have different thicknesses due to inaccuracies in the orientation. Consequently, the thicknesses 10 of the individual permanent magnet segments would have to be tolerated extremely tightly so that the desired length 9 of the segmented permanent magnet can be achieved as precisely as possible. With a liquid adhesive such tolerances can hardly compensate, because a liquid adhesive layer with a predefined thickness is difficult to apply. Furthermore, a liquid adhesive layer can only be compressed with difficulty under controlled conditions, since the adhesive layer subsequently becomes unevenly thick and the adhesive effect is thereby reduced.

In contrast, an adhesive layer 2 of a thermosetting plastic matrix with fiber reinforcement can be easily pressed, since the fiber reinforcement of the adhesive layer 2 gives sufficient stability for the pressing process. For this reason, the pressing process be controlled with high precision, so that such a high pressing force is built up that the segmented permanent magnet receives the desired length 9.

If, for example, as in FIG. 3 (a), the permanent magnet segments are too thick on average, an increased pressing force is applied, so that the adhesive layers 2 are compressed to thin adhesive layers 2 in the production process.

If, for example, as in FIG. 3 (b), the permanent magnet segments are on average too thin, a rather low pressing force is applied so that the adhesive layers 2 are only slightly compressed in the production process and thus remain as thick as possible.

In Fig. 4, the manufacturing process is shown in a simplified manner. After the cuboid permanent magnet segments 1 and the adhesive layers 2 were stacked with fiber reinforcement, the permanent magnet segments 1 and the adhesive layers 2 are compressed in a process step (a) with a hot pressing device 10 to the desired length and ver ^¬ sticks.

If, for example, an epoxy resin adhesive is used as the plastic matrix, the temperature during the hot pressing process should be higher than 140 ° C., in particular higher than 180 ° C., so that the plastic matrix hardens.

The fiber-reinforced adhesive layers 2 were cut slightly smaller than the available adhesive contact surfaces 3 before the hot-spraying process (a), so that sufficient space 11 remains for the adhesive layers 2 to expand during the pressing process, so that the adhesive layer 2 from the spaces between the adhesive contact surfaces 3 not partially exits (arrow 12) but only expands in the space 11. This müh ^¬ sam must be removed following the hot pressing process not beaten remnants of the adhesive layer. 2 After the hot pressing process, the permanent magnet segments 2 are magnetized. The magnetization of magnets constructed from permanent magnet material is well known to the person skilled in the art and will not be explained further here. The permanent magnets according to the invention are magnetizable in commercial Magnetisieranlagen.

In Fig. 4 (b), the segmented permanent magnet produced is illustrated, compared to the segmented permanent magnet (a) before the hot pressing process. It can be seen that the adhesive layers 2 have stretched by the hot pressing process to the outside, but not to the very edge of the adhesive contact surfaces 3, so that no residues of the adhesive layer 2 escaped from the space between the adhesive contact surfaces 3.

FIG. 5 illustrates a section through the adhesive layer 2, the sectional plane being shown in FIG. 4 (a). In Fig. 5, the edge region 6 can be seen, in which the adhesive contact surface 3 is free of the adhesive layer 2. In the present example, the edge region over the entire circumference of the adhesive contact surface 6 and has the same width 13 in the entire circumference.

The width of the edge surface 6 can, however, also be varied over the circumference, so that a larger edge region 6 is present at those points where a greater elongation of the adhesive layer 2 is to be expected.

In Fig. FIG. 5 also shows a surface coating 14 of the permanent magnet segment 1, which can be dispensed with with the present method.

While preferred embodiments of the invention are described in the present application, it should be clearly understood that the invention is not limited thereto and in any other way within the scope of the following claims.

Claims

claims

1. Segmented permanent magnet, comprising at least two permanent magnet segments (1) which are interconnected via at least one adhesive layer (2), characterized in that the at least one adhesive layer (2) consists at least partially of a thermosetting plastic matrix with fiber reinforcement (2a).

2. A segmented permanent magnet as claimed in claim 1. An ^¬, wherein the fiber reinforcement (2a) is designed as a continuous fiber reinforcement.

3. Segmented permanent magnet according to one of the preceding claims, wherein the fiber reinforcement (2a) is configured as a unidirectional layer and / or as a multi-directional layer and / or as a woven fabric and / or as a knitted fabric,

in particular wherein the fiber reinforcement (2a) has a plurality of fiber layers, in particular a plurality of fabric layers.

4. Segmented permanent magnet according to one of the preceding claims, wherein two of the at least two permanent magnet segments (1) are glued together via adhesive contact surfaces (3) of the permanent magnet segments (1) and one of the at least one adhesive layer (2) such that the one Adhesive layer (2) between the adhesive contact surfaces (3) is arranged.

5. A segmented permanent magnet according to claim 4, wherein the adhesive layer (2) extends only over part of the adhesive contact surfaces (3),

In particular, wherein an edge region (6) of the adhesive contact surfaces (3) is free of the adhesive layer (2), in particular wherein the edge region (6) via a entire circumference of the adhesive contact surfaces (3) is free of the adhesive layer (1),

in particular wherein the edge region a

Width (13) of 0.5 mm to 1 mm.

6. Segmented permanent magnet according to one of claims 4 to 5, wherein the permanent magnet segments (1) are additionally connected to each other in such a way that one of the at least one adhesive layer (2,7) on Außenf- surfaces (8) which to the adhesive contact surfaces (3) the intermediate adhesive layer (2) are arranged normally, the permanent magnet segments (1) is arranged.

7. Segmented permanent magnet according to one of the preceding claims, wherein the permanent magnet segments (1) have no surface coating (14), in particular made of resin.

8. Segmented permanent magnet according to one of the preceding claims, wherein the adhesive layer (2) in the bonded state has a thickness of less than 0.07 mm, in particular less than 0.05 mm, in particular less than 0.04 mm, in particular less than 0.03 mm.

9. A process for producing a segmented permanent magnet, in particular according to one of the preceding claims, wherein the following production steps comprise:

- stacking of permanent magnet segments (1) comprising magnetizable material or a magnetizable material and interposing at least one adhesive layer (2), the adhesive layer (2) consisting of a thermosetting plastic matrix with fiber reinforcement (2a);

- Hot pressing the permanent magnet segments

(1), at a temperature at which the plastic rix liquefied, in particular at a temperature higher than 140 ° C, in particular higher than 160 ° C, in particular ^¬ sondere higher than 180 ° C;

- Magnetizing the material of the permanent magnet segments (2).

10. The method of claim 9, wherein in hot pressing a pressing pressure is applied, such that the segmented permanent magnet is pressed to a predetermined length (9) or height.

11. The method according to any one of claims 9 to 10, wherein the at least one adhesive layer (2) prior to hot pressing a thickness of less than 0.1 mm, in particular less than 0.7 mm, in particular less than 0.5 mm, in particular less than 0.4 mm.

12. The method according to any one of claims 9 to 11, comprising the following step:

- Cutting the segmented permanent ^¬ magnet, in particular by means of wire erosion or by means of a diamond wheel or by means of a diamond thread or by means of a water jet.

13. The method according to any one of claims 9 to

12, wherein two of the permanent magnet segments (1) are glued together via K1ebekonta kt surfaces (3) of the permanent magnet segments (1) and one of the at least one adhesive layer (2), such that

before the hot pressing one of the at least one adhesive layer (2) is interposed and does not extend over the entire adhesive contact surfaces (3) of the permanent magnet segments (1), so that the adhesive layer (2) by hot pressing not on the adhesive contact surfaces (3) step out.

14. The method according to claim 13, wherein prior to hot pressing an edge region (6) of the adhesive contact surfaces (3) is free of the at least one adhesive layer (2), in particular wherein the edge region (6) extends over an entire circumference of the adhesive contact surfaces (3). free from the adhesive layer (2),

in particular wherein the edge region (6) has a width (13) of 0.5 mm to 1 mm.