DE20007580U1 - Device for the gentle delivery of single or multi-phase fluids - Google Patents

Description

&iacgr;&ogr; Device for the gentle conveyance of single or

multiphase fluids

Description

The invention relates to a device for the gentle conveyance of single-phase or multi-phase fluids according to the preamble of claim 1.

In particular, less stable multiphase fluids, which can undergo irreversible changes due to the input of energy, such as emulsions and dispersions, can disadvantageously enter unstable regions when pumped in corresponding devices such as pumps.

Blood is a particularly sensitive fluid system. This opaque red body fluid of vertebrates circulates in a closed vascular system, with rhythmic contractions of the heart pushing the blood into the various areas of the organism. The blood transports the respiratory gases oxygen and carbon dioxide as well as nutrients, metabolic products and the body's own active substances. The vascular system, including the heart, is hermetically sealed from the environment, so that in a healthy organism the blood

does not undergo any changes when it is pumped through the body via the heart.

It is known that blood tends to hemolysis and thrombus formation when it comes into contact with non-body materials or when exposed to external energy. The formation of thrombus can be fatal for the organism because it can lead to blockages in the extensive vascular system. Hemolysis describes the condition in which the red blood cells within the body are lysed beyond the physiological level.

- destroyed - The causes of hemolysis can be mechanical or metabolic. Increased hemolysis results in multiple organ damage and can even lead to death.

On the other hand, it has been shown that it is possible in principle, under certain structural conditions, to support the pumping performance of the heart or even to replace the natural heart with an artificial heart. However, the continuous operation of implanted heart support pumps or artificial hearts is currently only possible to a limited extent because the interactions of these artificial products with the blood still lead to adverse changes in the blood.

In the current state of the art, various directions of development of blood pumps can be identified. Depending on the required pressure difference and the volume flow, cardiac support pumps and artificial hearts can be designed either according to the displacement principle as so-called pulsatile pumps or according to the turbo principle as radial or axial flow machines. These three types of construction are currently

developed in parallel. Due to the high power density of this type of machine, the turbo machines are smaller in size than piston machines. Within the pumps that work according to the turbo principle, the axial pump variant is generally smaller than the radial one. In principle, a turbo machine can be designed very differently for a given pressure difference and a given volume flow, both as an axial and radial pump with very different speeds.

The axial blood pumps known from the prior art essentially consist of an outer cylindrical tube in which a conveying part, which is designed as a rotor of an externally attached motor stator, rotates and thus moves the blood in an axial direction. The bearing of the conveying part posed a problem. A purely mechanical bearing is disadvantageous in terms of blood damage and also the relatively high friction values. The magnetic bearing variants described so far have not led to a satisfactory solution either.

From Kawahito et al.: In Phase 1 Ex Vivo Studies of the Baylor/NASA Axial Flow Ventricular Assist Device, in:

Heart Replacement Artificial Heart 5, pages 245-252, Springer Verlag Tokyo 1996, editors T. Akutso and H. Koyagani, a generic axial blood pump for supporting a diseased heart is known, which can be implanted in the chest cavity of a patient. The axial blood pump has a rotating impeller with blades, which is mounted inside a blood-carrying tube and driven by an electric motor.

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For this purpose, the impeller is designed as the rotor of the electric motor and is coupled to the stator of the electric motor, which is fixed to the housing, via magnets mounted in the blades. The axial and radial bearing of the rotor is carried out via a tip bearing, in which the rotor is supported at certain points on bearing elements arranged in the flow. Such an arrangement is also known from US A 4,957,5 04.

The known blood pump has the disadvantage that the blood required is traumatized and damaged to a considerable extent. In particular, there is a risk of thrombus formation. The reason for this is essentially the formation of dead water areas at the bearings.
Another disadvantage is undoubtedly the limited service life of the mechanical bearings due to wear.

US Patent 4,779,614 describes an implantable axial blood pump that consists of an outer cylindrical tube and a rotor hub rotating in this tube for pumping blood. The rotor is magnetically mounted and simultaneously carries the rotor magnets of the drive and the rotor blades. The magnetically mounted rotor forms long, narrow gaps with the stator blades attached to the outer tube. The radial position of the rotor is to be stabilized by arranging two motor-stator combinations at each end of the pump. The position in the axial direction is stabilized by another pair of magnets, which are also to absorb the axial forces of the rotor. Although a relatively wide annular gap is provided for the fluid flow and the magnetic bearing of the rotor achieves important development goals for implantable

Although the advantages of a blood pump can be seen in terms of its compact design and freedom from sealing and bearing problems, this blood pump has serious disadvantages for the function and structural design of the pump. The extremely long, narrow gaps between the rotor hub and the guide vanes on the stator increase the risk of blood damage due to large velocity gradients of the gap currents. The arrangement of two motors required to stabilize the rotor is structurally complex. Furthermore, the rotor is not positively secured in the axial direction and therefore represents a residual risk.

US Patent 5,385,581 also describes an axial blood pump with magnetic bearings. The bearing magnets are arranged with opposite polarity in the rotor and stator area.

The disadvantage is that the pump stops if the bearings fail. Another disadvantage is that there is no so-called guide vane, which means that the entire pressure is built up by the impeller and the residual swirl remains in the flow.

The invention is based on the object of providing a device for the gentle conveying of single-phase and multi-phase fluids, which, with a simple structural design, does not or only insignificantly change the properties of the fluid to be conveyed, minimizes dead water areas and turbulences in the fluid to be conveyed and enables pulsating conveying.

The object is achieved according to the invention with the characterizing features of claim 1.

Preferred and advantageous embodiments of the invention are specified in the subclaims.

A solution according to the invention is characterized in that the conveying part arranged inside the tubular hollow body and capable of being set in rotation is mounted by means of a magnetic bearing. For this purpose, both permanent magnetic bearing elements for the magnetic bearing and permanent magnetic elements for the functionality as a motor rotor of an electric motor are preferably integrated into the conveying part. The use of a magnetic bearing makes it possible to dispense with bearing elements that are usually arranged in the flow of the fluid to be conveyed, which lead to dead water areas and turbulence in the fluid to be conveyed and thus have a negative effect on the flow.

Furthermore, a magnetic bearing is wear-free, so that a long service life is ensured, which is particularly important when used as a blood pump to support or replace the human heart and also leads to cost savings.

This design of the invention provides a simple construction, since mechanical bearing elements are dispensed with. The

magnetic storage required

In addition to the permanent magnet elements of the motor rotor, permanent magnet bearing elements are arranged directly on the conveyor part. The magnetic bearing advantageously absorbs both the axial and the radial forces.

In a preferred embodiment, axial stabilization is provided to stabilize the axial position of the conveying part. The axial stabilization provides active control of the axial position of the conveying part, with ring coils assigned to the front of the conveying part generating an axial magnetic flux that is superimposed on the axial magnetic flux of the permanent magnetic bearing elements and serves to control the axial position. Such stabilization arrangements are not known for the axial liquid pump or blood pump according to the invention.

For example, the permanent magnetic bearing elements of the magnetic bearing are integrated into the rotor hubs and the magnetic elements of the motor rotor are integrated into the conveying part. The conveying part according to the invention enables particularly favorable flow behavior of the fluid to be conveyed. The necessary rotor gap between the outside of the conveying part and the inside of the tubular hollow body is designed in such a way that both the motor losses and the flow losses caused by the gap are minimized. It should be noted that the motor losses that occur are greater the further the motor rotor is from the motor stator. A small rotor gap is therefore considered favorable on the motor side. On the other hand, however, a small rotor gap leads to large friction losses in the flow and is therefore unfavorable in terms of flow technology. A suitable compromise for blood pumps, for example, is the aforementioned rotor gap width of 0.5 to 2.5 mm.

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In a further embodiment of the invention, the conveyor part that can be set in rotation is characterized by a rotor hub, a blade that is connected to the rotor hub in a rotationally fixed manner, and an integration of the magnetic elements of the motor rotor and the permanent magnetic bearing elements of the magnetic bearing into the rotor hub and/or the blades. This minimizes the occurrence of flow losses in this embodiment. The permanent magnetic bearing elements of the magnetic bearing are preferably arranged in the rotor hub in this design. Permanent magnetic bearing elements are preferably arranged at both ends of the rotor hub for a rigid axial bearing of the conveyor part both in the direction of flow and against the direction of flow, which each interact with permanent magnetic bearing elements of an axially spaced fluid guide device. The magnetic elements of the motor rotor are arranged here between the two permanent magnetic bearing elements arranged at the ends.

A further advantageous embodiment of the invention is that sensors for detecting the current blood volume flow and the pressure difference currently generated by the pump are integrated into the hubs of the axial blood pump and/or into the wall of the tubular hollow body. Both measurement variables are available in the controller of the pumping device for target-actual comparisons and thus open up the possibility of regulating the pumping process in the sense of a physiologically optimal pulsatile pumping adapted to the natural action of the heart by means of a time-dependent change in the speed of the rotor or an optimized pumping system in the sense of low energy consumption.

pulsatile delivery by the pump, also realized by time-dependent speed change.

In a further advantageous development of the invention, means are provided on the front side of the rotor hub which convey fluid located in the hub gap between the fluid guide device and the conveying part radially outwards, such as radial blading, grooves, bulges or spherical shapes.

A further advantageous embodiment of the invention consists in that an axially extending bore is provided in at least one of the fluid guide devices, through which the fluid to be conveyed flows and which causes fluid located in the hub gap between the fluid guide device and the conveying part to be transported radially outwards.

Both of the aforementioned developments influence the radial pressure distribution and generate compensating flows to prevent dead water areas in the hub gap between the front sides of the fluid guide device and the conveying part.

In a further embodiment of the invention, the conveying part, in particular the rotor hub, has two blades at an axial distance. This forms a so-called tandem cascade.
This advantageously reduces the pressure increase required for each row of blades. In addition, this special design of the rotor of the conveyor device further limits disruptive tilting movements.

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Further embodiments of the invention are characterized in that the bearing of the rotor is achieved by combining a magnetic axial bearing with a mechanical radial bearing. An advantageous further development is characterized in that the hubs have axle stumps on their front side facing the rotor, which, in conjunction with plain bearing bushes that are inserted into the rotor at the front and protrude into the axle stumps, take over the radial bearing of the rotor with very high rigidity, or that there is a continuous axle that is inserted into the front sides of the hubs and on which the rotor is radially mounted with high rigidity by means of plain bearing bushes. In these embodiments of the invention, the axial bearing of the rotor is realized by means of repelling, permanent magnetic bearing elements in the rotor hub and in the hubs of the fastening elements.

A further advantageous embodiment of the invention is characterized in that the rotor hub has axle stumps on both sides, which rotate in plain bearing bushes located in the front sides of both hubs and in this way ensure a radial bearing with high rigidity. In this embodiment of the invention, the axial bearing of the rotor is realized via repulsive, permanent magnetic bearing elements in the rotor hub and in the hubs of the fastening elements.

The invention is explained in more detail below with reference to the figures of the drawing.

Show it

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Fig. 1 an axial blood pump in sectional view,

Fig. 2 an axial conveyor device with magnetic bearing, axial stabilization and position sensors in longitudinal section,
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Fig. 2a is a sectional A-A view of the axial conveying device according to Fig. 2,

Fig. 2b an axial conveyor device with magnetic holder in longitudinal section,

Fig. 2c is a sectional A-A view of the axial conveying device according to Fig. 2b,

Fig. 2d an axial conveyor device with conical

Conveyor section in longitudinal section,

Fig. 3a a magnet holder for an axial conveyor device,
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Fig. 3b the magnet holder according to Fig. 3a in cross section,

Fig. 4 a conveyor section with double blading,
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Fig. 5 a fluid guide device with position sensor and permanent magnetic bearing element,

Fig. 5a the fluid guide device according to Fig. 5 in the representation section B-B,

Fig. 6 an axial conveyor device with axial same-polarity (repulsive) magnetic bearing combined with a radial axle bearing,

Fig. 6a an axial conveyor device with radial axle bearing, stabilizers and opposite bearing magnet polarity (attractive),

Fig. 7a is a schematic front view of the front side of a rotor hub or hub,

Fig. 7b is a schematic front view of the front side of another rotor hub or hub,

Fig. 7c a schematic front view of the front side

a rotor hub or hub with eccentric elevation,

Fig. 8 is a schematic sectional view of a hub gap formed between the conveyor part and

Hub of a fastening element,

Fig. 8a is a schematic sectional view of a hub gap formed between the conveyor part and the hub of a fastening element and

Fig. 9 is a schematic sectional view through a hub with axial bore.

Fig. 1 shows an exemplary embodiment of a blood pump according to the invention with pump housing 3 and stabilizer housing 2. Outside a tubular hollow body 1, in which the fluid is conveyed in the axial direction, a motor stator 31 with motor windings 33 is arranged around the hollow body 1. The motor stator 31 drives a conveying part 5, which contains a motor rotor 32 and a rotor hub 52 and which is mounted inside the tubular hollow body 1.

The rotor hub 52 has rotor blades 53. In the flow direction in front of and behind the rotor hub 52, fluid guide devices 7 and 7' with fluid guide blades 72 and 72' are fixed to the inner wall of the tubular hollow body 1. A so-called hub gap 9 is formed between the fluid guide devices 7 and 7" and the rotor hub 52. The motor rotor 32, which is combined with the rotor hub 52, can be set in rotation via the motor stator 31.

When the blood pump is operating, the outflowing blood is fed through a bend 6 to the conveying part 5 and is set in rotation there by means of the rotor blades 53, whereby the rotor hub 52 ensures favorable flow dynamic conditions. The fluid guide device 7' with its blades 72" which is firmly connected to the hollow body 1 upstream ensures a flow-technically advantageous flow to the rotor blades 53. The pressure sensor 60 allows pressure measurement in the incoming fluid. The conveying part 5 is driven in a manner known per se by magnetic coupling of the motor rotor 32 with the motor stator 31. The formation of thrombi when blood is the medium to be conveyed is greatly minimized because, due to the magnetic bearing, no bearing elements are arranged in the flow which could cause dead water areas to form. Turbulence and the associated flow losses only occur to a small extent. A rotor gap 8 between the rotor hub 52 and the inner wall of the hollow body 1 has a width which keeps the flow losses small and at the same time also limits the motor losses which increase with increasing distance of the motor rotor 32 from the motor stator 31. A width of the Rotor gap 8 between

0.5 and 2.5 mm. After the fluid has been accelerated by the rotor blades 53 of the rotor hub 52 and the pressure builds up as a result, the fluid is guided into the fluid guide device 7, where it is deflected in the axial direction and a further pressure builds up. The shape of the fluid guide blades 72 of the fluid guide device 7 ensures that the deflection of the fluid in the axial direction takes place gently and also essentially without turbulence.

The blood leaves the blood pump via a bend 6" and flows into an aortic cannula 62, which is attached to the bend 6" by means of a detachable connecting element 63. A specially shielded cable 11a, which contains the supply and signal lines for the motor stator 31, the axial stabilizer 12 and the sensors 60, 61 and 43, is connected to the blood pump via the cable connector 11.
The function of the magnetic bearing is described in Fig. 2 and 2a.

Fig. 2 and Fig. 2a also show, in longitudinal section and in cross section, another exemplary embodiment of a blood pump with a magnetically mounted rotor hub 52. In the rotor hub 52, the motor rotor 32 is combined with permanent magnetic bearing elements 42 arranged at each end, which are held in a holder 4. In the fluid guide devices 7 and 8, permanent magnetic bearing elements 41 are arranged directly opposite permanent magnetic bearing elements 42. The permanent magnetic bearing elements 41 and 42 are oppositely polarized here. The axially directed attraction force that develops between the permanent magnetic bearing elements 41 and 42

ensures that the conveying part 5 is held coaxially in the tubular hollow body 1 and radial deflections are corrected. Position sensors 43, which are also arranged in the fluid guide devices 7 and ' , determine the width of the hub gap 9 and regulate this via the axial stabilizer 12. The axial stabilizer 12 is arranged in a stabilizer housing 2. The axial stabilizers 12, designed as coils, generate a magnetic field when the current is switched on, which is guided via the stabilizer housing 2 and the flux guide pieces 10 so that the conveying part 5 assumes a stable axial position between the fluid guide devices 7 and 7'. Pressure sensors 60 and a flow sensor 61 for characterizing the flow are attached to the ends of the fluid guide devices 7 and 7' and to the outer wall of the tubular hollow body 1. The conveying part 5, which consists of the motor rotor 32 and the permanent magnetic bearing elements 42 as well as the rotor blades 53, is set in rotation via the motor stator 31. Radial deviations in the rotation are absorbed by the oppositely polarized permanent magnetic bearing elements, while axial stabilization is achieved via the position sensors 43 and the axial stabilizers 12. The concentration of the main mass of the permanent magnetic bearing elements 42 in the area of the axis of the conveying part 5 enables the pump to be operated in a pulsatile mode, for example by quickly changing the speed of the rotor.

Alternatively, the permanent magnetic bearing elements 41 and 42 are designed as permanent magnetic rings with axial magnetization instead of as solid cylinders. Any

Designs can be used for the precise formation of the permanent magnetic bearing elements 41 and 42.

To stabilize the axial position of the conveying part 5 or the rotor hub 52, an axial stabilizer 12 is provided in an exemplary embodiment, which interacts with position sensors 43 and acts on the front side of the conveying part 5 via the fluid guide devices 7 and ^7λ and uses an electronic control circuit not shown here. The axial stabilizer 12 actively regulates the axial position of the conveying part 5, with the stabilization coils being supplied with currents in accordance with the regulation carried out and thereby generating an axial magnetic flux that overlays the axial magnetic flux of the permanent magnetic elements and serves to regulate the axial position. The position sensors 43 detect deviations from the axial target position of the conveying part 5 and forward this information to the control circuit.

Fig. 2b and Fig. 2c show a further exemplary embodiment of a device according to the invention in longitudinal and cross-section. The holders 75, which are arranged in front of and behind the conveying part 5 in the direction of flow, consist of a hub 73, which is fastened to the inner wall of the tubular hollow body 1 with supports 74. The supports 74 are arranged here, for example, at a distance of 90° around the hub 73. In principle, one support 74 would also be sufficient. The holder 75 essentially serves to accommodate the permanent magnetic bearing elements 41. The opposing permanent magnetic bearing elements 41 and 42 are also

here oppositely polarized. The axial stabilization is provided by the axial stabilizer 12, the position sensor 43 and a control electronics (not shown).

In Fig. 2d, in another exemplary embodiment, the conveying part 5 and the fluid guide device 7 are conical. A conical rotor 80 of the conveying part 5 increases in the direction of flow and continues to increase in size conically until it merges into a conical guide device 81. The permanent magnetic bearing elements 41 and 42 are polarized in opposite directions, and the axial stabilization is also achieved here via the position sensors 43 in conjunction with the axial stabilizer 12.

Figures 3a and 3b show, in longitudinal and cross - section, in detail an exemplary embodiment of the bracket 75 with supports 74.

Fig. 4 shows a conveying part 5 with the rotor hub 52, around which two rotor blades 53 and 53" are arranged. The arrangement of two or more rotor blades 53 makes it possible to increase the effect of the blading of the conveying part 5.

In Fig. 5 and Fig. 5a, fluid guiding devices 7 and 7" are shown in longitudinal and cross-section, respectively, in which the permanent magnet bearing element 41 is surrounded by the position sensor 43.

Fig. 6 shows a further embodiment of the device according to the invention. Here, the magnetic bearing is combined with a mechanical radial bearing. The permanent magnetic bearing elements 41

and 42 are polarized in the same direction. The mechanical bearing consists of an axis 44 which is firmly fixed in the fluid guide devices 7 and 7', while the other end of the axis 4 is rotatably mounted in a bearing bush 45 of the conveying part 5. Due to the polarization of the opposite permanent magnetic bearing elements 41 and 42 in the same direction, axial stabilization is advantageously not required here. The radial stabilization takes place via the axis 44.

In Fig. 6a, in which a mechanical radial bearing is also combined with a magnetic bearing, the permanent magnetic bearing elements 41 and 42 are oppositely polarized in contrast to Fig. 6. This makes it necessary to arrange axial stabilizers 12 in the stabilizer housing 2, to provide position sensors 43 and control electronics.

Measures which influence the radial pressure distribution and bring about compensating flows to prevent dead water areas in the area of the rotor hub 52, i.e. in the hub gap 9 between the end faces of the fluid guide device 7 and 7' and the conveying part 5, are shown in Fig. 7a, b, c, 8 and 8a. In Fig. 7a, a rib 723 extending radially outward from the center is arranged on an end face 722 of the fluid guide device 7, ⁷¹ .
In Fig. 7b, the rib 724 is curved. Instead of such ribs, convex and/or concave curvatures, radial blades, microblades, ribs, grooves and eccentric elevations 725 (Fig. 7c) of any shape or simply a rough surface can be provided on the front side 722. The only decisive factor is that these are means by which the fluid can be

Rotation of the conveying part 5 radially out of the hub gap 9 (see Fig. 9). Of course, these means can also be arranged on the front side of the rotor hub 52.

The representation according to Fig. 8 advantageously also brings about an improvement in the emergency running properties in the event of failure of the axial stabilization.

In Fig. 9, the hub 73 has an axial bore 72 6 through which the fluid to be pumped flows and causes fluid located in the hub gap 9 to be additionally transported radially.

It is pointed out that the magnetic bearing according to the invention is not limited to cylindrical shapes of the magnets. Other geometric designs of the permanent magnetic bearing elements 41 and 42 are possible.

The invention does not only relate to the above-mentioned embodiments. The only essential aspect of the invention is that the conveying part 5 of the axial pump or blood pump is mounted in the tubular hollow body 1 by means of magnetic bearings.

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List of reference symbols

1 Tubular hollow body

2 Stabilizer housing

3 Pump housing 4 Socket

5 Conveyor part

6 manifold 6" manifold

7 Fluid guidance device 7' Fluid guidance device

8 Rotor gap

9 Hub gap

10 Flow guide

11 Cable gland 11a Cable

12 Axial stabilizer

31 Motor stator

32 Motor rotor

41 permanent magnetic bearing element

42 permanent magnet bearing element

43 Position sensor

44 Axis

45 Bearing bush 51

52 Rotor hub

53 Rotor blading

60 Pressure sensor

61 Flow sensor

62 Aortic cannula

63 Connecting element

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72 Fluid Guide Blades 72" Fluid Guide Blades

73 Hub

74 Support

75 Bracket
76 hub cap.

722 Front side

723 Rib

724 Rib

725 increase
72 6 Bore

80 conical rotor

81 conical guide device

Claims (18)

1. Device for the gentle conveyance of single-phase or multi-phase fluids, consisting of a tubular hollow body ( 1 ) which guides the fluid essentially axially and in which a conveying part ( 5 ) which can be set in rotation with a motor stator ( 31 ) located outside the hollow body ( 1 ) is mounted in axial alignment, characterized in that the conveying part ( 5 ) which can be set in rotation is mounted between two fastening elements ( 7 , 7 ', 75 ) fixed in the hollow body ( 1 ), each separated without contact by a hub gap ( 9 ), wherein both the fastening elements (7, 7', 75) and the conveying part ( 5 ) have functionally interacting bearing elements ( 41 , 42 and/or 44 , 45 ). 2. Device according to claim 1, characterized in that sensors ( 43 ) and stabilizers ( 12 ) for position detection and position correction of the conveying part ( 5 ) are arranged in the fastening elements ( 7 , 7 ', 75 ) and on or in the wall of the hollow body ( 1 ). 3. Device according to claim 1 or 2, characterized in that for flow characterization pressure and flow sensors ( 60 , 61 ) are arranged in the fastening elements ( 7 , 7 ', 75 ) and/or on or in the wall of the hollow body ( 1 ). 4. Device according to one of claims 1 to 3, characterized in that the functionally interacting bearing elements ( 41 , 42 , 44 , 45 ) have permanent magnetic bearing elements ( 41 , 42 ) which are arranged opposite one another in the fastening elements ( 7 , 7 ', 75 ) and in the conveying part ( 5 ). 5. Device according to one of claims 1 to 4, characterized in that the functionally cooperating bearing elements ( 41 , 42 , 44 , 45 ) have flux guide pieces ( 10 ) which are arranged in the fastening elements ( 7 , 7 ', 75 ). 6. Device according to one of claims 1 to 5, characterized in that the conveying part ( 5 ) is mounted radially and rotatably on two axes ( 44 ). 7. Device according to one of claims 1 to 5, characterized in that the conveying part ( 5 ) is rotatably mounted radially on a continuous axis ( 44 ). 8. Device according to one of claims 1 to 7, characterized in that the axis ( 44 ) is firmly connected to the conveyor part ( 5 ) or to the fastening elements ( 7 , 7 ', 75 ). 9. Device according to one of claims 1 to 8, characterized in that the axis ( 44 ) is rotatably mounted radially in a bearing bush ( 45 ). 10. Device according to one of claims 1 to 9, characterized in that the opposing permanent magnetic bearing elements ( 41 , 42 ) have the same polarity. 11. Device according to one of claims 1 to 9, characterized in that the opposing permanent magnetic bearing elements ( 41 , 42 ) are oppositely polarized. 12. Device according to one of claims 1 to 11, characterized in that when the permanent magnetic bearing elements ( 41 , 42 ) have opposite polarity, a stabilizer ( 12 ) is arranged for axial stabilization of the conveying part ( 5 ). 13. Device according to one of claims 1 to 12, characterized in that the fastening elements ( 7 , 7 ', 75 ) are designed as fluid guiding devices ( 7 , 7 ') with fluid blading ( 72 ). 14. Device according to one of claims 1 to 13, characterized in that ribs (723, 724) as well as blading, grooves, convex and/or concave bulges or eccentrically arranged elevations (725) are attached to the end faces (722, 723 ) of the fastening elements ( 7 , 7 ' , 75 ) facing the conveying part (5) and/or to the end faces of the conveying part ( 5 ). 15. Device according to one of claims 1 to 14, characterized in that an axially extending bore ( 726 ) is arranged in at least one of the fastening elements ( 7 , 7 ', 75 ). 16. Device according to one of claims 1 to 15, characterized in that the rotor hub ( 52 ) of the conveying part ( 5 ) has two rotor blades ( 53 ) at an axial distance. 17. Device according to one of claims 1 to 16, characterized in that the rotor hub ( 52 ) and the hubs ( 73 ) are cylindrical and the hubs ( 73 ) are closed by hub caps ( 76 ) at the end facing away from the conveying part ( 5 ). 18. Device according to one of claims 1 to 17, characterized in that the conveying part ( 5 ) and the holders ( 75 ), even when designed as fluid guiding devices ( 7 , 7 '), are non-cylindrically enlarged or tapered in the flow direction.