EP1797330B1 - Arrangement for delivering fluids - Google Patents

Abstract

An arrangement for delivering fluids has a fluid pump having a pump wheel (90), which wheel is joined to a first permanent magnet (92). The pump wheel (90) is rotatably arranged inside a liquid-tight pump housing (80, 82, 84, 86, 88). This housing is shaped, near the first permanent magnet (92), as a partitioning can (80, 82). The arrangement also has an electronically commutated electric motor (20) having a stator (22) and a rotor (26) arranged rotatably relative thereto, which rotor comprises a second permanent magnet (67) that coacts with the first permanent magnet (92) to act as a magnetic coupling (94). Arranged in the space between the second permanent magnet (67) and partitioning can (80, 82) is a plurality of soft ferromagnetic magnetic flux conductors (150).

Description

The invention relates to an arrangement for conveying fluids. As fluids liquid and / or gaseous media can be promoted.

In computers today components with high heat flux densities are used, for example 60 W / cm ² . From these components, the heat must first be transferred to a liquid circuit, and from this circuit, the heat must be discharged through a liquid-to-air heat exchanger to the ambient air.

The dissipation of the heat of components with high heat flux density by means of so-called heat receivers or cold plates. In these, the heat is transferred to a cooling liquid, and this is usually placed in a circuit in forced circulation.

In this case, the cooling liquid flows through not only the heat absorber, but also a liquid pump, which causes the forced circulation and an adequate pressure build-up and an adequate volume flow through the heat exchanger and an associated heat exchanger causes, so that the heat transfer coefficients associated with these heat transfer large and the heat transfer necessary temperature gradient become small. Such arrangements are, for example WO 2004/031588 . JP 06 241185 . US 6,600,649 . JP 09 163 675 or off DE 4301675 bekamt.

In the heat exchanger usually a fan is arranged, which causes a forced convection of the cooling air and good transfer coefficients on the air side of the heat exchanger.

In such cooling arrangements fan and liquid pump are driven separately, and these components are often spatially separated. Therefore you need two drives, which usually work rotationally. These drives require energy and also quite a lot of space, both of which are undesirable.

It is therefore an object of the invention to provide a new fluid delivery system.

According to the invention, this object is achieved by the subject matter of claim 1. This gives a very compact arrangement with good efficiency, wherein the soft ferromagnetic magnetic flux conductors bridge the space between the containment shell and the second permanent magnet and thereby a greater distance between the first permanent magnet and enable the second permanent magnet of the magnetic coupling.

Fig. 1

einen Längsschnitt durch eine bevorzugte Ausführungsform der Erfindung, gesehen längs der Linie I-I der Fig. 5,

Fig. 2 und 3

eine Explosionsdarstellung der Anordnung nach Fig. 1,

Fig. 4

eine schematische Darstellung zur Erläuterung der Erfindung,

Fig. 5

einen Schnitt, gesehen längs der Linie V-V der Fig. 1,

Fig. 6

eine raumbildliche Darstellung einer Anordnung mit Flussleitblechen, nach einer Variante der Erfindung,

Fig. 7

eine vergrößerte Ausschnittsdarstellung aus Fig. 6, welche Vorsprünge zeigt, die beim Ultraschallschweißen verformt werden und dabei eine örtliche Schweißverbindung herstellen,

Fig. 8

eine Draufsicht von unten auf die Anordnung der Fig. 6, gesehen in Richtung des Pfeiles VIII der Fig. 6,

Fig. 9

eine Draufsicht von oben auf die Anordnung der Fig. 6, gesehen in Richtung des Pfeiles IX der Fig. 6,

Fig. 10

eine schematische Darstellung der Befestigung der Anordnung gemäß Fig. 6 mittels Aufpressen und Ultraschallschweißen,

Fig. 11

eine Ausschnittsvergrößerung,

Fig. 12

die Anordnung gemäß Fig. 10 nach ihrer Montage,

Fig. 13

eine raumbildliche Darstellung einer Anordnung mit Flussleitblechen, gemäß einer weiteren Variante der Erfindung,

Fig. 14

eine vergrößerte Ausschnittsdarstellung aus Fig. 13,

Fig. 15

einen horizontalen Schnitt durch die Anordnung gemäß Fig. 13,

Fig. 16

einen Ausschnitt aus Fig. 15,

Fig. 17

einen Schnitt durch ein Flussleitblech der Fig. 13, und

Fig. 18

und 19 zwei schematische Darstellungen zur Erläuterung der Montage des Rotors und seiner Lager bei der Anordnung nach Fig. 1 bis 3.

Further details and advantageous developments of the invention will become apparent from the following described and illustrated in the drawings, in no way as a limitation of the invention to be understood embodiments, and from the dependent claims. It shows:

Fig. 1

a longitudinal section through a preferred embodiment of the invention, as seen along the line II of Fig. 5 .

FIGS. 2 and 3

an exploded view of the arrangement according to Fig. 1 .

Fig. 4

a schematic representation for explaining the invention,

Fig. 5

a section, seen along the line VV the Fig. 1 .

Fig. 6

a three-dimensional representation of an arrangement with flux guide plates, according to a variant of the invention,

Fig. 7

an enlarged detail view Fig. 6 which shows projections that are deformed during ultrasonic welding and thereby produce a local weld,

Fig. 8

a plan view from below of the arrangement of Fig. 6 , seen in the direction of the arrow VIII of the Fig. 6 .

Fig. 9

a top view of the arrangement of Fig. 6 , seen in the direction of the arrow IX of the Fig. 6 .

Fig. 10

a schematic representation of the attachment of the arrangement according to Fig. 6 by means of pressing and ultrasonic welding,

Fig. 11

an enlarged detail,

Fig. 12

the arrangement according to Fig. 10 after their assembly,

Fig. 13

a three-dimensional representation of an arrangement with flux guide plates, according to another variant of the invention,

Fig. 14

an enlarged detail view Fig. 13 .

Fig. 15

a horizontal section through the arrangement according to Fig. 13 .

Fig. 16

a section from Fig. 15 .

Fig. 17

a section through a Flußleitblech the Fig. 13 , and

Fig. 18

and FIG. 19 are two diagrams for explaining the assembly of the rotor and its bearings in the arrangement according to FIG Fig. 1 to 3 ,

In the following description, the terms left, right, up, down refer to the respective drawing figure. Identical or equivalent parts are denoted by the same reference numerals in the various figures, possibly with trailing apostrophes, e.g. 150 and 150 '.

Fig. 1 shows an enlarged view of an arrangement with an electronically commutated external rotor motor 20. This has an inner stator 22 of Conventional construction, as exemplified in Fig. 2 is shown in section, for example, a stator with salient poles or a claw-pole stator, and this is separated by a substantially cylindrical air gap 24 from a permanent-magnetic outer rotor 26, its structure also made Fig. 2 is particularly clear. In operation, the outer rotor 26 rotates about the inner stator 22, which is why such motors 20 are referred to as external rotor motors.

The inner stator 22 is mounted on a bearing tube 30 made of a suitable plastic, usually by pressing. The shape of the bearing tube 30 is made Fig. 2 and 3 especially clear. Right of the indoor stator 22 is located in Fig. 1 a printed circuit board 32. On this are, for example (not shown here) electronic components that are needed for electronic commutation of the motor 20, also a rotor position sensor 34 which is controlled by a permanent magnet ring 36 of the outer rotor 26. The magnet ring 36 is radially magnetized and preferably has four rotor poles. Its magnetization, that is, the distribution of its magnetic flux density may be, for example, rectangular or trapezoidal. The sensor 34 is controlled by a stray field of the magnetic ring 36, which allows a non-contact detection of the position of the rotor 26.

The outer rotor 26 has a construction with a so-called rotor bell 40, which is designed here as a deep-drawn, cup-shaped sheet metal part made of soft ferromagnetic material. The magnetic ring 36 is fixed in this sheet metal part 40, so that it forms a magnetic yoke for the rotor magnet 36.

The sheet metal part 40 is fixed to a hub 44 in which a shaft 46 is fixed in the manner shown. The shaft 46 is mounted in two ball bearings 48, 50, the outer rings are held by a spacer 52 at a distance from each other, see. the schematic representations in the Fig. 18 and 19 , These ball bearings 48, 50 are, together with the shaft 46, in the assembly in Fig. 1 Pressed from the left into the bearing tube 30 and held there by a locking member 54, see. Fig. 18 and 19 , For pressing the locking member 54 is an axial projection 56 of the flange 44. Between the latter and the inner ring of the rolling bearing 48 is a compression spring 58, which, based on Fig. 1 , after assembly, the rotor 26th press so far to the left until a mounted at the right end of the shaft 46 snap ring 59 abuts against the inner ring of the bearing 50. The shaft 46 is thus displaceable in this type of assembly in the inner rings of the two bearings 48, 50. Naturally, this type of assembly is only one preferred embodiment. Many other types are possible.

This type of assembly makes it possible Fig. 1 to mount the rotor 26 together with its pre-assembled bearings 48, 50 from the left in the bearing tube 30, so that the in Fig. 1 right end 60 of the inner recess of the bearing tube 30 may be closed liquid-tight as shown. Based on the following Fig. 18 and 19 this type of assembly is explained in more detail.

The outside of the sheet metal part 40 is surrounded by a plastic part 63, in which fan blades 64 are formed in the manner shown by plastic injection molding. These rotate during operation in a recess 66 of a fan housing 68, see. Fig. 3 , The fan housing 68 preferably has the usual square basic shape of a device fan and has in its corners in each case a mounting hole 70. The plastic part 63 has in Fig. 1 right a continuation part 65 in which a permanent magnet 67 is attached, which is part of a magnetic coupling.

The bearing tube 30 goes into Fig. 1 to the right about in a flange-like portion 80 which is perpendicular to the axis of rotation 81 of the rotor 26 and merges at its periphery in a cylindrical portion 82, which here has the function of a so-called split tube and therefore hereinafter referred to as a gap tube 82. This is via a shoulder 84 in a cylindrical portion 86, the free end, as shown, for fixing a lid 88 is used, for example by laser welding. On the lid 88, an inlet nozzle 96 is provided for cooling liquid. In the housing part closed by the cover 88, a delivery wheel 90 is rotatably arranged. The bearing tube 83 is as shown preferably integrally with the parts 82, 84, 86 made of a magnetically transparent plastic.

The feed wheel 90 is preferably formed integrally with a permanent magnetic rotor 92 which forms a magnetic coupling 94 with the permanent magnet 67, ie when the permanent magnet 67 rotates, the permanent magnet 92 also rotates, thereby driving the delivery wheel 90, whereby this liquid sucks through the inlet 96 and pumped through an outlet 98 to the outside, as indicated by arrows. Of course, any other turbomachine may be provided instead of a spiral pump, for example a compressor for a refrigerant.

As can be seen from the drawings, the distance from the permanent magnet 67 to the permanent magnet 92 is large, so that a direct transmission of the torque between these two magnets would not be possible. For this reason, a plurality of magnetic flux conductors in the form of Flußleitkörpern 150 are disposed between the magnets 67, 92, which image the magnetic field of the rotating permanent magnet 67 on the gap tube 82 and thereby cause a rotation of the permanent magnet 92.

Fig. 2 shows approximately half of the Flussleitkörper 150 in perspective view, and Fig. 4 explains their mode of action. The flux guide 150 have at Fig. 1 and 2 the shape of pentagonal plates made of dynamo plate, so softferromagnetic material. They are in the embodiment according to Fig. 1 to 5 embedded with their radially inner ends in the gap tube 82, see. Fig. 5 , and widening, starting from this, towards radially outward. They are arranged in a star shape, z: B. in the form according to Fig. 5 , Their outer ends 152 are separated by a magnetic air gap 154 from the permanent magnet 67. ("Magnetic air gap" is a term used in electrical engineering.) Even a magnet that is magnetically transparent can form such an "air gap", ie it has a magnetic effect like air.)

Fig. 4 shows an instantaneous rotational position of the magnet 67, which is shown in four poles, as well as the magnet 92. The latter is shown in simplified form. In this position, there is a pole boundary 156 between two adjacent poles of the magnet 67 approximately in the position 12.30 clock, based on the dial of a clock. To the left of the boundary 156, the flux guide bodies 150 face south poles S, to the right of the boundary 156, on the other hand, they face north poles N. The flux guide 150 extend here in each case in radial planes and at a distance from each other, whereby they are magnetically isolated from each other. They are preferably distributed uniformly around the circumference in order to avoid the development of reluctance moments and magnetic preferred positions.

Accordingly, south poles S, which attract the north pole N of the permanent magnet 92, are also formed on the radially inner end of the flux guide body 150 to the left of the pole boundary 156.

To the right of the pole boundary 156, the flux guide bodies 150 face north poles N, and accordingly north pole N, which attract a south pole of the permanent magnet 92, are located at the radially inner end of the flux guide body 150 there.

The outer magnet 67 rotates clockwise, as in Fig. 5 As shown, the poles also migrate at the inner ends of the flux guide 150 and thus cause rotation of the inner permanent magnet 92 at the same speed. The arrangement according to Fig. 4 works according to the principle of a synchronous motor. (Alternatively, in special cases, operation with slippage is not excluded, which presupposes the use of special materials in the magnetic coupling 94, as known to the person skilled in the art.)

By the Flußleitkörper 150 so the distance between the magnets 67 and 92 is bridged, so that the magnet 92 may have a small diameter. This is important because the magnet 92 rotates in the cooling fluid, and consequently, with a small diameter of the magnet 92, low friction losses occur in that cooling fluid. This contributes to a good efficiency of the arrangement.

The permanent magnet 92 of the fluid pump is rotatably supported by means of a sliding bearing 100 on a stationary shaft 106, which is fixed in a liquid-tight manner in a protruding projection 107 of the portion 80 in the manner shown. At the right end of the shaft 106, a snap ring (not shown) may be provided. By the adjacent Flussleitkörper 150, the magnet 92 is attracted and held in the illustrated axial position.

For the illustrated type of attachment of the bearings 48, 50 is required in Fig. 1 a free space 109 between the right end of the shaft 46 and the bottom of the recess 60. The configuration with the projection 107 allows despite this free space 109 an axially compact design.

The cylindrical portion 86 is connected via radially extending webs 114 with the fan housing 68, so that this forms a one-piece plastic part with the split tube 82, the portion 80 and the bearing tube 30, which simplifies the assembly of the assembly, the number of parts keeps small, and the units used safely separated from each other, so that liquid from the turbomachine 90 can not get to the electric motor 20 and damage it. The stationary shaft 106 also forms part of this injection-molded part, because it is anchored in this in the manufacture, and therefore also contributes to the compact design.

operation

In operation, the external rotor motor 20 drives the outer rotor 26, so that the fan blades 64 rotate in the housing 68 and thereby generate an air flow therein. Alternatively, the fan can also be designed as a diagonal or radial fan. Shown is an axial fan.

At the same time, the magnet ring 67 drives the rotor magnet 92 via the flux guide bodies 150 and through the gap tube 82 and thus rotates the impeller 90, so that this liquid sucks through the inlet 96 and pumps out through the outlet 98. Such a pump may e.g. used to aspirate and pump water in a fountain, or to pump blood in a cardiopulmonary bypass, or to transport cooling fluid in a closed cooling circuit, the impeller 90 then having the function of a circulation pump.

Since the lid 88 is liquid-tightly connected to the cylindrical part 86, for example by laser welding, no liquid can escape from the housing 88 to the outside. This contributes to the fact that the section 80 and its projection 107 are free of openings of any kind. This is possible because the rotor 26, eg in the following at Fig. 18 and 19 described manner, can be mounted very easily and it is not necessary during assembly to in Fig. 1 right end of the shaft 46 to have access. Likewise, that can Impeller 90 of the centrifugal pump with its sliding bearing 100 in Fig. 1 be mounted from the right on the stationary shaft 106 before the lid 88 is attached. Through the Flussleitkörper 150 ensures that the rotor 26 can be easily pushed over this Flussleitkörper 150 including its axial extension 65 and the permanent magnet 67 during assembly without this complicated assembly work is necessary. Before assembly of the rotor 26, the entire remaining part of the arrangement can be completely assembled, because it is possible because of the Flußleitkörper 150 to make the outer diameter in the region of these bodies 150 larger than the outer diameter of the inner stator 22 and the circuit board 32nd

alternative to Fig. 1 can be provided for the storage of the impeller 90, a rotating shaft which is stored as well as the shaft 46 of the motor 20 in a (not shown) bearing tube, which is then - as the bearing tube 30 - is integrally formed with the section 80 and this protrudes to the right, so mirror image of the bearing tube 30th

According to Fig. 18 that differ slightly from the representation in the Fig. 1 to 5 differs 20 different components are pre-assembled on the shaft 46 prior to assembly of the motor.

Starting at the projection 56, this is first the compression spring 58, whose end of larger diameter is located in a recess 39. This spring is followed by the annular securing member in the form of the securing disk 54. The spring 58 does not bear against the securing member 54.

On the securing member 54, the rolling bearing 48 follows with its outer ring 48e and its inner ring 48i. The latter is displaceable on the shaft 46 in the axial direction. The lower end of the spring 58 abuts against the upper end of the inner ring 48i. The roller bearing 48 is followed by the spacer 52, which is displaceably guided on the shaft 46 by means of a radially inwardly projecting projection 53 and whose upper end abuts, as illustrated, against the lower end of the outer ring 48e.

On the spacer 52, the lower roller bearing 50 follows with its outer ring 50 e, which rests with its upper end against the spacer 52 and with its inner ring 50 i, which is axially displaceable on the shaft 46 and with its lower end against the snap ring 59th is applied when the motor 20 is fully assembled.

As can readily be seen, one can, when pressing with a force F up on the lower roller bearing 50, compress the spring 58 while the two bearings 48, 50, the spacer 52 and the lock washer 54 on the shaft 46 upwards move, so that the inner ring 50i no longer abuts against the snap ring 59, but gets a distance from him. In this case, the projection 56 of the rotor 22 comes to rest against the lock washer 54 and allows it to transmit an axial force on the lock washer 54, the outer ring 48e, the spacer 52 and the outer ring 50e via this, when the rotor 26 by a Force K is pressed down during assembly.

Fig. 19 shows a snapshot in the process of "marriage", in which the shaft 46 of the rotor 26 is inserted with the rolling bearings 48, 50 thereon in the inner recess 77 of the bearing tube 30.

Here, a force K is applied to the rotor 26 in the axial direction, and since the outer rings 48e, 50e of the rolling bearings 48, 50 are press-fitted into the bearing tube 30, the spring 58 is compressed by the force K, so that the shaft 46 in the ball bearings 48, 50 moves and the projection 56 via the lock washer 54, the outer ring 48e of the ball bearing 48 and the spacer 52 and the outer ring 50e of the ball bearing 50 is applied and so presses the two ball bearings 48, 50 in the bearing tube 30.

The press-fitting continues until the outer ring 50e of the lower ball bearing 50 abuts against the upper end of ribs 83 provided in the bearing tube 30 at the inner end 60 thereof.

This shifts according to Fig. 19 the securing member 54 in the bearing tube 30 and digs it in its plastic material, so that it locks the entire bearing assembly in the bearing tube 30.

After the complete pressing in, the force K is removed, and the image then follows Fig. 1 ie, the spring 58 now pushes the shaft 46 again until the snap ring 59 bears against the inner ring 50i of the rolling bearing 50. The spring 58 now braces the two inner rings 48i, 50i against each other, what a smooth running of the engine 20th is beneficial.

The 6 to 12 show a first variant for the attachment of Flußleitkörpern 150 'on a plastic ring 160. The latter has a cylindrical recess 162, with which he according to 10 to 12 is pushed onto the split tube 82. On its outside, it has projections 164 in which the flux guide bodies 150 'are anchored in the manner shown.

The ring 160 is on his in the Fig. 6, 7 and 10 to 12 bottom side provided with projections 168 which have approximately the shape of a wedge. By applying an ultrasonic transducer in the direction of arrows 170 of Fig. 10 It is achieved that these projections 168 dig into the shoulder 84 and welded thereto.

The split tube 82 may have a smaller wall thickness in this case.
The FIGS. 13 and 14 show a similar embodiment, but with a wedge-like blade 174 is provided which extends continuously. The attachment is the same as in the 10 to 12 shown.

Fig. 15 shows a section through a ring 160 and anchored in this Flußleitkörper 150 ". Fig. 16 shows in an enlarged scale that the flux guide bodies 150 "are wedge-shaped in this variant at the radially inner end in order to effect a secure anchoring Fig. 17 the Flussleitkörper 150 "at the radially inner end of a hook-like widening 180th

As for the expert Fig. 1 Clearly, the Flußleitkörper 150 also act as flux concentrators, because they have at their radially outer portion about the same length as the magnet 67, while at their radially inner portion about the - shorter - length of the magnet 92 have, so that the flow of the magnet 67 is concentrated. This also takes into account the fact that the magnets 67 and 92 are unequal in length and improves the torque that can be transmitted from the magnetic coupling.

Naturally, many modifications and modifications are possible within the scope of the present invention.

Claims (23)

1. Arrangement for conveying fluids, which has:

   a fluid pump, which has an impeller (90), which is connected to a first permanent magnet (92), which impeller (90) is arranged rotatably inside a fluid-tight pump casing (80, 82, 84, 86, 88), which casing (80, 82, 84, 86, 88) is formed in the area of the first permanent magnet (92) as a split pot (80, 82); an electronically commutated electric motor (20) with a stator (22) and a rotor (26) arranged rotatably relative to this, which has a second permanent magnet (67), which interacts with the first permanent magnet (92) in the manner of a magnetic coupling (94), characterized in that the arrangement has a plurality of soft ferromagnetic magnetic flux conductors (150; 150'; 150") arranged in the space between the second permanent magnet (67) and the split pot (80, 82), which conductors are arranged at a distance from one another such that they map the magnetic field of the second permanent magnet (67) active at their end facing away from the split pot (80, 82) onto the area of the split pot (80, 82) assigned to the first permanent magnet (92).
2. Arrangement according to claim 1, in which the soft ferromagnetic magnetic flux conductors (150; 150'; 150") are formed as bodies of soft ferromagnetic material, which are arranged roughly in a star shape around the split pot (80, 82).
3. Arrangement according to claim 2, in which the bodies (150; 150'; 150") of soft ferromagnetic material are formed substantially in the shape of a plate.
4. Arrangement according to one of the preceding claims, in which the soft ferromagnetic magnetic flux conductors (150; 150'; 150") are formed in the manner of flux concentrators.
5. Arrangement according to one of the preceding claims, in which the electronically commutated electric motor is formed as an external rotor motor (20) with a rotor bell (63), inside which the rotor magnet (36) of the motor (20) and the second permanent magnet (67) are arranged.
6. Arrangement according to one of the preceding claims, in which inside the split pot (80, 82) and arranged on this is a bearing element (106) for the impeller (90) and outside the split pot (80, 82) and arranged on this is a bearing element (30) for the rotor (26) of the electronically commutated electric motor (20).
7. Arrangement according to claim 6, in which the bearing element for the rotor (26) of the electric motor (20) has a bearing tube (30), which is fixedly connected to the split pot (80, 82).
8. Arrangement according to claim 7, in which the bearing tube (30) is formed in one piece with the split pot (80, 82).
9. Arrangement according to one of the preceding claims, in which connected to the rotor (26) of the electric motor (20) are fan blades (64).
10. Arrangement according to claim 9, in which the permanent magnet of the rotor has a magnetic return path, which is formed as a cup-shaped part (40), and the fan blades (64) are arranged on this cup-shaped part (40).
11. Arrangement according to claim 9 or 10, in which the fan blades (64) are formed as part of an axial fan wheel.
12. Arrangement according to claim 9 or 10, in which the fan blades are formed as part of a diagonal fan wheel.
13. Arrangement according to claim 9 or 10, in which the fan blades are formed as part of a radial fan wheel.
14. Arrangement according to one of the preceding claims, in which connected to the split pot (80, 82) is an air guide casing (68).
15. Arrangement according to claim 14, in which the air guide casing (68) is formed as a one-piece part of synthetic material with the split pot (80, 82).
16. Arrangement according to claim 15, in which the split pot (80, 82) is connected to the air guide casing (68) via at least one web (114).
17. Arrangement according to claim 7 or 8, in which the electric motor is formed as an external rotor motor (20), and the internal stator (92) of this motor is fastened on the bearing tube (30), which serves to support the rotor (26).
18. Arrangement according to one of the preceding claims, in which the soft ferromagnetic magnetic flux conductors (150; 150'; 150") are connected at their radially inner end area to a carrier part (160) of non-ferromagnetic material.
19. Arrangement according to claim 18, in which the carrier part (160) is arranged on the split pot (80, 82).
20. Arrangement according to claim 19, in which the split pot (80, 82) has a roughly circular-cylindrical periphery, and the carrier part (160) is arranged on this periphery.
21. Arrangement according to one of claims 18 to 20, in which the carrier part (160) is formed from a synthetic material and is provided with axial projections (168; 174), which are connected to an adjacent synthetic material part of the arrangement by a welding process.
22. Arrangement according to claim 21, in which the welded joint is formed by ultrasonic welding (170) at an axial end of the carrier part (160).
23. Arrangement according to one of the preceding claims, in which the cross-section of soft ferromagnetic magnetic flux conductors (150") inside the carrier part (160) is enlarged (180) at least in areas, to bring about good anchoring of these conductors (150") in the carrier part.

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