Magnetic suspension device and centrifugal pump

Abstract

The invention relates to a magnetic levitation device for contactless magnetic levitation of a rotor comprising a disc-shaped or annular magnetic effective core. A magnetic levitation device has a stator including a plurality of coil cores, each coil core including a longitudinal leg extending in an axial direction from a first end to a second end and a transverse leg arranged at the second end of the longitudinal leg and extending in a radial direction perpendicular to the axial direction. A concentrated winding is provided at and around each longitudinal leg. The stator has a cup-shaped recess into which the rotor is insertable. The cup-shaped recess is arranged at an axial end of the stator. The transverse legs are arranged around the cup-shaped recess. A plurality of magnetic field sensors for determining the position of the rotor are arranged around the cup-shaped recess. An annular holding device is provided for the magnetic field sensors, which has a cavity for each magnetic field sensor. The cavity is defined by an inner sidewall and an outer sidewall relative to the radial direction. The magnetic field sensor can be pushed into the cavity, and the inner side wall and the outer side wall abut against the magnetic field sensor.

Description

Technical Field

[0001] The invention relates to a magnetic levitation device according to the preamble of the independent patent claim and to a centrifugal pump having such a magnetic levitation device. Background Art

[0002] Magnetic bearing devices for contactless magnetic support of rotors have the following advantages: They do not require mechanical bearings for the rotor. The rotor is supported or stabilized by means of magnetic forces generated by the stator of the magnetic bearing device. Due to the absence of mechanical bearings, such magnetic bearing devices are particularly suitable for use in pumping, mixing, centrifuging or stirring devices with which very sensitive substances are conveyed, such as blood pumps, or for which very high demands are made in terms of purity, such as in the pharmaceutical industry or biotechnology, or for conveying abrasive or aggressive substances that would very quickly destroy mechanical bearings, such as pumps or mixers for slurries, sulfuric acid, phosphoric acid or other chemicals in the semiconductor industry.

[0003] In the biotechnology industry, such magnetic bearing devices are used, for example, in conjunction with bioreactors, for example in centrifugal pumps for conveying fluids into or out of a bioreactor, or in mixing devices for mixing fluids in a bioreactor. In the semiconductor industry, such magnetic bearing devices are used not only for conveying aggressive or abrasive substances, but also, for example, in rotating devices, with which wafers are rotated.

[0004] It is also known to use magnetic bearing arrangements for viscometers.

[0005] An advantageous design of a magnetic bearing device known per se is that in the form of a temple, to which the present invention also relates.

[0006] The characteristic feature of the temple construction is that the stator of the magnetic bearing device has a plurality of coil cores, each of which includes a longitudinal leg extending from a first end to a second end in an axial direction. Here, the axial direction refers to the direction defined by the desired axis of rotation of the rotor supported by the magnetic bearing device. The desired axis of rotation is the axis of rotation about which the rotor rotates in an operating state when the rotor is in a centered and non-tilted position relative to the stator. In addition to the longitudinal legs, each coil core includes a transverse leg, which is arranged at the second end of the longitudinal leg in each case and extends in a radial direction, usually toward the inside, wherein the radial direction is perpendicular to the axial direction. Therefore, the transverse leg extends substantially at right angles to the longitudinal leg. The coil cores each have an L-shape, wherein the transverse leg forms the short leg of the L. The rotor to be supported is then arranged between the transverse legs.

[0007] The multiple longitudinal legs extending in the axial direction and reminiscent of temple columns give the construction its name.

[0008] In one design, the stator of the magnetic bearing device has, for example, six coil cores which are arranged circularly and equidistantly around a cup-shaped recess into which the rotor can be inserted. The first ends of the longitudinal legs are usually connected in the circumferential direction via a back iron, which serves to conduct the magnetic flux. The rotor to be supported comprises a magnetically active core, for example a permanent magnetic disk or a permanent magnetic ring, which is arranged between the radially inner ends of the transverse legs and rotates about the axial direction in the operating state, wherein the rotor is magnetically supported relative to the stator without contact.

[0009] For such magnetic bearing arrangements, the magnetically active core of the rotor does not necessarily have to be designed in a permanent-magnetic manner. Such designs are also known in which the magnetically active core of the rotor is designed in a non-permanent-magnetic manner, i.e. without permanent magnets. The magnetically active core of the rotor is then, for example, designed in a ferromagnetic manner and is made, for example, of iron, nickel-iron, cobalt-iron, silicon-iron, mu metal or another ferromagnetic material.

[0010] Furthermore, designs are possible in which the magnetically active core of the rotor comprises both ferromagnetic material and permanent magnet material. For example, permanent magnets may be placed or inserted into a ferromagnetic matrix. Such designs are advantageous, for example, if one wishes to reduce the cost of a large rotor by saving permanent magnet material.

[0011] The longitudinal legs carry windings for generating the electromagnetic fields required for the contactless magnetic bearing of the rotor. For example, the windings are designed such that one concentrated winding is wound around each longitudinal leg, i.e. the coil axis of each concentrated winding extends in each case in the axial direction. Here, it is typical for a temple construction that the coil axis of the concentrated windings extends in the axial direction and the concentrated windings are not arranged in a radial plane in which the rotor or the magnetically active core of the rotor is supported in the operating state.

[0012] A design is possible in which exactly one concentrated winding is arranged on each longitudinal leg. In other designs, several (e.g. exactly two) concentrated windings are provided on each longitudinal leg. A design is also possible in which the winding is arranged to be wound around two longitudinal legs adjacent in the circumferential direction so that both of these two adjacent longitudinal legs are located in the interior of the concentrated winding.

[0013] For a reliable and safe contactless magnetic bearing of the rotor, it is very important to know the current position of the rotor in the radial plane with high accuracy in each case, so that the position of the rotor in the radial plane can be adjusted to the desired position. To determine the rotor position, it is known (for example from WO 2014 / 036419) to arrange a plurality of magnetic field sensors, for example Hall sensors, in a magnetic bearing arrangement so that they are arranged around the magnetically active core of the rotor. The current position of the rotor is then determined as accurately as possible from the signals of the magnetic field sensors. However, since the magnetic field sensors detect all magnetic fields at their respective positions, i.e., for example, also the stator magnetic field, it is usually very difficult to determine the exact position of the rotor in the radial plane from the signals of the magnetic field sensors. Summary of the invention

[0014] Starting from this state of the art, the object of the present invention is therefore to provide a magnetic levitation device for contactless magnetic levitation of a rotor having an annular or disk-shaped magnetically active core, wherein the rotor position can be determined reliably and with very high accuracy by means of a magnetic field sensor. Furthermore, the object of the present invention is to provide a centrifugal pump having such a magnetic levitation device.

[0015] The subject matter of the invention which meets this object is characterized by the features of the independent patent claims.

[0016] According to the invention, a magnetic levitation device for contactless magnetic levitation of a rotor is thus proposed, the rotor comprising a disk-shaped or annular magnetically active core, wherein the magnetic levitation device has a stator, the stator comprising a plurality of coil cores, each of the coil cores comprising a longitudinal leg extending from a first end in an axial direction to a second end, and a transverse leg arranged at the second end of the longitudinal leg and extending in a radial direction perpendicular to the axial direction, wherein at least one concentrated winding is provided at each longitudinal leg, the winding surrounding the respective longitudinal leg, wherein the stator also has a cup-shaped recess into which the rotor can be inserted, wherein the cup-shaped recess is arranged at an axial end of the stator, wherein the transverse legs are arranged around the cup-shaped recess, and wherein a plurality of magnetic field sensors for determining the position of the rotor are arranged around the cup-shaped recess. An annular holding device is provided for the magnetic field sensor, the annular holding device having a cavity for each magnetic field sensor, the cavity being delimited by an inner side wall and by an outer side wall with respect to the radial direction, wherein the magnetic field sensor can be pushed into the cavity, and wherein the cavity is dimensioned so that the inner side wall and the outer side wall lie flat against the magnetic field sensor.

[0017] Due to the fact that an annular holder is provided, which has a cavity for each magnetic field sensor, the cavity being dimensioned such that the inner and outer side walls lie flat against the magnetic field sensor, the respective positions of the magnetic field sensors are known with extremely high accuracy. In particular, the position of the magnetic field sensor relative to the cup-shaped recess is known with high accuracy, which enables the position of the rotor in the cup-shaped recess to be determined very accurately. In particular, the position of the respective magnetic field sensor is only defined by the position of the cavity and does not depend, for example, on how the magnetic field sensor is soldered to a circuit board or glued to a structure. Even if the position of the magnetic field sensor is determined by a connection such as soldering or gluing, this generally leads to placement inaccuracies, which have a negative impact on the accuracy of the rotor position determination. Since in an embodiment according to the invention the soldered or glued connection cannot influence the position of the magnetic field sensor, this leads to a very high accuracy of the rotor position determination.

[0018] According to a preferred embodiment, a circuit board is arranged between the winding and the transverse leg with respect to the axial direction, on which all magnetic field sensors are arranged, and the holding device is designed to receive the circuit board. This has the advantage that all magnetic field sensors can first be connected to the circuit board, whereby electrical connections for controlling the magnetic field sensors and for receiving measurement signals are created on the circuit board. Subsequently, the circuit board with the connected magnetic field sensors is then inserted into the holding device, wherein the magnetic field sensors are pushed into the cavity. Finally, the circuit board is securely connected to the holding device, for example by means of screws and / or by means of a potting compound poured into the holding device.

[0019] Here, it is preferred that the holding device has an annular edge on which a shoulder is provided, wherein the shoulder is arranged radially inwardly relative to the edge and wherein the circuit board rests on the shoulder. Thus, the shoulder forms a support for the circuit board so that it can be placed in the holding device in a very simple manner.

[0020] Furthermore, it is preferred that the edge is designed such that it protrudes beyond the circuit board with respect to the axial direction.Due to this measure, it is possible to pot the holding device with a potting compound, wherein the circuit board is completely covered by the potting compound.

[0021] According to a preferred embodiment, the holding device has a separate recess for each coil core, which recess surrounds the coil core and receives a transverse leg of the coil core.

[0022] In this case, it is advantageous if each cavity is arranged between two adjacent recesses with respect to the circumferential direction. This makes it possible for each magnetic field sensor to be arranged in each case between two adjacent coil cores with respect to the circumferential direction.

[0023] According to a particularly preferred embodiment, exactly six coil cores are provided in the magnetic levitation device.

[0024] Furthermore, it is preferred that the magnetic levitation device comprises exactly six magnetic field sensors, which are preferably arranged equidistantly around the cup-shaped recess.

[0025] In a preferred embodiment, the holding device is filled with a first potting compound such that the circuit board is completely covered by the potting compound. The first potting compound is particularly preferably a soft potting compound. In the context of this application, a soft potting compound means a potting compound with a Shore hardness D of less than 40. For example, silicone or polyurethane are suitable as the first potting compound.

[0026] According to a particularly preferred embodiment, the coil core with the winding arranged thereon is arranged in a housing which is potted with a second potting compound, wherein the second potting compound is a thermally conductive potting compound. The second thermally conductive potting compound is a hard thermal potting compound, such as an epoxy resin. As a result, the first potting compound and the second thermal potting compound are different from each other. During operation of the magnetic levitation device, strong and frequent temperature fluctuations may occur, in particular in the region of the holding device in which the magnetic field sensor is arranged. A soft potting compound is more resistant to such fluctuations. Therefore, a soft potting compound is preferred for potting the holding device, which is softer than the hard potting compound used for potting the housing. In particular, the second potting compound surrounding the coil core and the winding arranged thereon preferably has a particularly good thermal conductivity in order to dissipate the generated heat, such as heat generated by copper losses and iron losses, as efficiently as possible. In order to achieve a high thermal conductivity, a filler material with good thermal conductivity is preferably added to the second thermal potting compound, such as graphite powder, carbon fibers, carbon nanotubes, aluminum oxide powder, boron nitride powder or other ceramic powders. These fillers improve the thermal conductivity, but also cause a higher hardness of the hardened potting compound. Therefore, the second thermal potting compound has a greater hardness, in particular a greater Shore D hardness, than the first potting compound.

[0027] With regard to positioning the magnetic field sensor as accurately as possible, it is advantageous to provide a separate guide element for each cavity, which guide element forms the inner or outer side wall by which the cavity is delimited. Such separate guide elements are generally easier to manufacture with very high accuracy than the entire holding device, which is manufactured, for example, by means of an injection molding process. In order to form the cavity for the magnetic field sensor, the separate guide element is inserted in the axial direction into a recess in the holding device provided for this purpose, so that it then forms the inner or outer side wall that delimits the cavity with respect to the radial direction. Preferably, the separate guide element is connected to the holding device in a form-locking manner, for example by means of a press fit.

[0028] Preferably, the stator has a receiving pot which forms an axial end of the stator, wherein the receiving pot has a cup-shaped recess into which the rotor can be inserted and wherein the receiving pot surrounds the holding device radially outwards. In this preferred embodiment, the receiving pot is preferably designed as a separate receiving pot which has a cup-shaped recess. In particular, for constructional reasons, it is preferred that the receiving pot surrounds the second holding device radially outwards. In this case, the axial end region of the second holding device is arranged inside the receiving pot and is completely surrounded by it when viewed in the circumferential direction.

[0029] Preferably, the holding device is made of plastic.For example, the holding device is designed as an injection molded part manufactured by means of an injection molding process.

[0030] Furthermore, it is preferred that the holding tank is made of plastic. The holding tank can also be designed as an injection-molded part.

[0031] According to a preferred embodiment, the magnetic levitation device has a housing, which includes a stator housing and a control housing arranged adjacent to each other with respect to the axial direction, wherein the stator housing is designed to receive a coil core on which a concentrated winding is arranged, and the control housing is designed to receive a control unit for controlling the winding and supplying electrical energy to the winding for generating an electromagnetic field.

[0032] Preferably, the housing is designed such that the coil core with the concentrated windings arranged thereon can be inserted into the stator housing in a first mounting direction in the axial direction and the control unit can be inserted into the control housing in a second mounting direction, wherein the first mounting direction points in a direction opposite to the second mounting direction. The housing preferably has two regions separated from each other, wherein one of the regions forms the stator housing and the other forms the control housing. For example, the two regions can be separated from each other by a wall having a passage, for example for an electrical connection. The housing is then preferably designed in one piece with respect to the circumferential direction.

[0033] According to a particularly preferred embodiment, the stator of the magnetic levitation device is designed to generate a torque, with which the rotor can be driven magnetically without contact for rotation about an axial direction.

[0034] Furthermore, the invention proposes a centrifugal pump for conveying fluids, which comprises the magnetic levitation device according to the invention and a rotor with a magnetically active core, wherein the rotor can be inserted into a cup-shaped recess of a receiving tank and wherein the rotor is designed as a rotor of a centrifugal pump.

[0035] Further advantageous measures and embodiments of the invention are apparent from the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following, the present invention will be explained in more detail with reference to an embodiment and with reference to the drawings. In the drawings:

[0037] Figure 1 : A cross-sectional view of an embodiment of a magnetic levitation device according to the present invention,

[0038] Figure 2 : From the perspective exploded view Figure 1 A perspective illustration of an embodiment of

[0039] Figure 3 : A perspective view of the stator and the retaining device,

[0040] Figure 4 : Perspective exploded view of the coil core, winding and retaining device,

[0041] Figure 5 : A perspective illustration of the holding device from the direction of the first end of the longitudinal leg of the coil core,

[0042] Figure 6 :like Figure 5 , but from the opposite viewing direction,

[0043] Figure 7 : A perspective exploded view of the holding device and the circuit board with the magnetic field sensor,

[0044] Figure 8 : A cross-sectional illustration of a holding device with a circuit board inserted therein,

[0045] Fig. 9 : Enlarged image from Figure 8 Details of I,

[0046] Fig.10 : From Fig. 9 A perspective illustration of the guide element of

[0047] Fig.11 : a cross-sectional view of the stator containment tank, and

[0048] Fig.12 : A schematic cross-sectional illustration of an embodiment of a centrifugal pump according to the present invention, in a section along the axial direction. DETAILED DESCRIPTION

[0049] Figure 1 A cross-sectional view of an embodiment of a magnetic levitation device according to the invention is shown, which is designated in its entirety by reference numeral 1. The magnetic levitation device 1 is designed for contactless magnetic levitation of a rotor 3 which comprises a disk-shaped or annular magnetically active core 31 .

[0050] For better understanding, Figure 2 The exploded view still shows the Figure 1 A perspective illustration of an embodiment of the present invention, whereby the rotor 3 is not in Figure 2The magnetic levitation device 1 is designed according to the temple construction and comprises a stator 2 having a plurality of coil cores 25, here six coil cores 25, each of which comprises a longitudinal leg 26 extending from a first end 261 in the axial direction A to a second end 262, and a transverse leg 27 arranged perpendicular to the longitudinal leg 26, the transverse leg 27 extending in a radial direction perpendicular to the axial direction A. Each transverse leg 27 is delimited with respect to the radial direction by an end face 271, which forms a pole of the associated coil core 25.

[0051] At least one concentrated winding 61 (in the present embodiment exactly one) is provided on each longitudinal leg 25 , the concentrated winding 61 surrounding the corresponding longitudinal leg 26 .

[0052] The magnetic levitation device 1 includes a housing 10 in which a coil core 25 is arranged.

[0053] For better understanding, Figure 3 and Figure 4 A further illustration of the stator 2 of an exemplary embodiment of the magnetic levitation device 1 is shown, whereby the housing 10 is not present. Figure 3 A perspective view of the stator 2 and the holding device 9 is shown, which will be described in more detail. Figure 3 In the embodiment, a back iron 22 is provided, which connects all first ends 261 of the longitudinal legs 26, that is, according to the diagram ( Figure 1 ) are connected to each other and used to conduct magnetic flux. Preferably, the back iron 22 is designed in an annular manner. Figure 4 A perspective exploded view of the coil core 25 and the holding device 9 is shown, on which the concentrated winding 61 is arranged.

[0054] The housing 10 is preferably made of a metallic material, such as aluminum or stainless steel. For better chemical resistance, the housing 10 may be provided with a coating, preferably a plastic coating made of a highly chemically resistant plastic. Examples of such plastics are PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy polymer), ECTFE (ethylene chlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), epoxy resin (polyepoxy resin), PPA (polyphthalamide), PE (polyethylene). Depending on the intended application, the housing 10 may also be made of titanium or chrome steel.

[0055] The stator 2 further comprises a receiving pot 21 having a cup-shaped recess 211 (see also Fig.11 ), into which the rotor 3 to be suspended can be inserted (see Figure 1 The receiving tank 21 forms one of the two axial ends of the stator 2 or the magnetic suspension device 1. Figure 1 , which is the upper axial end of the stator 2. A housing cover 11 of the closed housing 10 is arranged at the other axial end of the magnetic levitation device 1.

[0056] The receiving tank 21 is firmly connected to the housing 10, for example by means of a form-locking connection and / or by means of an elastic seal 201. Preferably, the receiving tank 21 is connected to the housing 10 in an airtight manner. The housing cover 11 is firmly connected to the housing 10, for example by means of a screw 111 ( Figure 1 ), whereby the sealing element 105 is optionally arranged between the housing cover 11 and the housing 10. The sealing element 105 can be designed in particular as a flat seal. Preferably, the housing cover 11 is connected to the housing 10 in a gas-tight and sealed manner.

[0057] Particularly preferably, the housing 10 together with the receiving pot 21 and the housing cover 11 forms a hermetically sealed housing in which other components of the stator 2 are encapsulated in a hermetically sealed manner. The housing 10 is preferably filled with a potting compound having good thermal conductivity (for example, with epoxy resin) so that the components arranged inside the housing 10 are surrounded by the potting compound. In this way, the general heat resistance is reduced and vibrations are weakened.

[0058] Preferably, the housing cover is made of plastic. Particularly for applications in chemically aggressive environments, chemically resistant plastics such as polypropylene are preferred.

[0059] The transverse leg 27 of the coil core 25 is arranged in the receiving pot 21 such that an end face 271 of the transverse leg 27 is arranged around the cup-shaped recess 211 .

[0060] The coil cores 25 of the stator 2 are arranged equidistantly on a circular line so that when the rotor 3 is inserted into the cup-shaped recess 211, the end face 271 surrounds the magnetically active core 31 of the rotor 3. Precisely one concentrated winding 61 is provided at each longitudinal leg 26, which surrounds the longitudinal leg 26.

[0061] In other embodiments, more than one concentrated winding may also be arranged at the longitudinal leg 26. For example, there are embodiments in which exactly two concentrated windings are provided at each of the longitudinal legs 26, each of which surrounds the respective longitudinal leg 26, wherein the two windings arranged on the same longitudinal leg 26 are arranged adjacent to one another with respect to the axial direction A.

[0062] The concentrated winding 61 is used to generate an electromagnetic field, and the rotor 3 can be magnetically suspended in the cup-shaped recess 211 of the accommodating pot 21 without contact with the electromagnetic field.

[0063] Furthermore, a control unit 40 is provided for controlling the winding 61 and supplying the winding 61 with electrical energy. The control unit 40 comprises in particular power electronics, such as an inverter or a rectifier, which feeds the required current into the winding 61. The control unit 40 is Figure 1 and Figure 2Particularly preferably, the control unit 40 is also arranged inside the housing 10, for example according to the diagram ( Figure 1 ) is arranged below the first end 261 of the longitudinal leg 26 of the coil core 25. The control unit 40 is preferably also potted or coupled to the housing 10 and the back iron 22 and / or the coil core 25 of the stator 2 with a thermal potting compound. Preferably, the control unit 40 includes an electronics board 41 on which various electronic components 42 are arranged.

[0064] As in particular Figure 1 and Figure 2 As can be seen in the figure, the housing 10 preferably comprises two areas separated from each other and arranged adjacent to each other with respect to the axial direction A, one of which forms a stator housing 101 and the other forms a control housing 102. The stator housing 101 of the housing 10 is designed to receive the coil core 25 on which the winding 61 is arranged, and the control housing 102 is designed to receive the control unit 40.

[0065] According to a preferred measure, the housing 10 comprises an inner cup 13, which is designed in a substantially cylindrical manner and is arranged radially inwards with respect to the winding 61 in the inner space surrounded by the winding 61. The inner cup 13 is connected to the outer wall 15 of the housing 10 via a flange-like projection 14. The outer wall 15 forms the radial outer boundary of the housing 10. Particularly preferably, the inner cup 13 and the flange-like projection 14 are components of the housing 10. The outer wall 15, the flange-like projection 14 and the inner cup 13 are designed as a whole in one piece and form the housing 10, which is preferably in one piece.

[0066] The inner cup 13 and the flange-like projection 14 separate a region of the housing 10 that forms the stator housing 101 from a region that forms the control housing 102 .

[0067] As in particular Figure 1 As can be seen in FIG. 1 , the inner cup 13 connected to the flange-like protrusion 14 extends from the radial inner edge of the flange-like protrusion 14 in the axial direction A and is arranged radially inwardly relative to the winding 61 and the back iron 22 in the inner space surrounded by the winding 61. With respect to the radial direction, the inner cup 13 is arranged adjacent to the longitudinal legs 26 of the coil core 25 or the winding 61 arranged thereon, so that the inner cup 13 can particularly well absorb and dissipate the heat generated by the winding 61 and the coil core 25. With respect to the axial direction A, the inner cup 13 extends generally upward to the cup-shaped recess 211 of the accommodating pot 21.

[0068] As in particular Figure 2As can be seen in the figure, the stator housing 101 of the housing 10 is designed with an interior space, which has a substantially circular or annular cross-sectional area perpendicular to the axial direction A. This is preferred because the stator housing 101 can thus receive the annular back iron 22 particularly well, wherein the coil core 25 is arranged around the back iron 22. The control housing 102 of the housing 10 is designed with an interior space, which has a substantially rectangular or square cross-sectional area perpendicular to the axial direction A. This is preferred because the control housing 102 is thus particularly suitable for receiving the preferably rectangular or square electronic device board 41 of the control device 40. In particular with regard to production, a rectangular or square design of the electronic device board 41 is much simpler than, for example, a circular design.

[0069] Due to this embodiment of the stator housing 101 and the control housing 102, the axial end of the stator 2 (at which the housing pot 21 closes the housing 10) has a substantially circular cross section, so that the housing pot 21 has a circular or annular design. In contrast, the axial end of the stator 2 (at which the housing cover 11 closes the housing 10) has a substantially rectangular or square cross section, so that the housing cover 11 has a rectangular or square design.

[0070] Using the exemplary features, Figure 1 4 . Some components of the control unit 40 are presented in FIG. 4 . For example, the control unit 40 comprises an electronics board 41 on which electronic components 42 are provided, such as power electronics for controlling the winding 61. For example, the electronics board 41 may also contain evaluation electronics for evaluating signals from sensors, such as magnetic field sensors, or may be used as a communication interface. The electronics board 41 is preferably designed as an electronic printed circuit board or PCB (printed circuit board). In addition, a connecting cable 45 is provided, which is connected to the electronics board 41 via a cable connector (not presented) or a plug. The connecting cable 45 is led out of the housing 10 and is used, for example, to supply power to the magnetic levitation device 1. The connecting cable 45 is led out of the housing 20 by means of a cable bushing 47 of sealed design. Preferably, the cable bushing 47 is designed in an airtight sealing manner.

[0071] The electronics board 41 of the control unit 40 is connected to the windings 61 via connecting lines (not shown), such as cables, in order to control them and supply them with energy. It is understood that a feedthrough or opening is provided between the control housing 102 and the stator housing 101, through which the connecting lines pass. Such a feedthrough can be arranged, for example, in the flange-like protrusion 14 or in the inner cup 13.

[0072] The electronics board 41 is preferably arranged directly on the flange-like projection 14, so that the electronics board rests on the flange-like projection 14. In this way, it is possible to dissipate the heat generated in the control unit 40 in a particularly effective manner via the housing 10. Preferably, the main heat source in the control unit 40, such as a circuit breaker for the winding 61, is arranged in the region of the electronics board 41 resting on the flange-like projection 14.

[0073] The interior space of the inner cup 13 (ie the space enclosed by the inner cup 13) can be used for further electronic components, electronic device boards or plugs or connectors. For reasons of better overview, these are not shown in FIG. Figure 1 Presented in.

[0074] According to a particularly preferred embodiment, the stator 2 is designed such that, in addition to the contactless magnetic suspension of the rotor 3, it can also exert a torque on the rotor 3 or the magnetically active core 31 of the rotor 3, which torque drives the rotor 3 to rotate around a desired axis of rotation. Here, the desired axis of rotation is designated as the axis about which the rotor 3 rotates in the operating state when the rotor 3 is in a centered and non-tilted position relative to the stator 2 (e.g. Figure 1 The desired rotation axis extends in the axial direction A, i.e., in the preferred embodiment, the rotor 3 arranged in the receiving pot 21 of the stator 2 can be driven for rotation around the axial direction A. Typically, the desired rotation axis coincides with the center axis of the stator 2, which extends in the axial direction A.

[0075] In this exemplary embodiment, the concentrated windings 61 thus generate an electromagnetic rotating field, with which the rotor 3 can be both magnetically suspended relative to the stator 2 without contact and driven for rotation about the axial direction A without contact.

[0076] It is to be understood that the number of six coil cores 25 (although preferred) is understood only as an example. Of course, such embodiments in which the stator 2 has less than six (e.g., five or four or three) coil cores 25 or such embodiments in which the stator 2 has more than six (e.g., seven or eight or nine) coil cores 25 or any larger number of coil cores 25 are also possible.

[0077] The rotor 3 comprises a magnetically active core 31 which is designed in an annular or disk-shaped manner. Figure 1 As shown in the figure, the magnetically effective core 31 is designed as a ring and defines a magnetic center plane. Alternatively, the magnetically effective core 31 can also be designed as a disk. Generally, in the case of a disk-shaped or ring-shaped magnetically effective core 31, the magnetic center plane is the geometric center plane of the magnetically effective core 31 of the rotor 3, which is perpendicular to the axial direction A. In the operating state, the magnetically effective core 31 is suspended in a radial plane E perpendicular to the axial direction A. The radial plane is Figure 1In the diagram, the radial plane E is indicated by a line E which is perpendicular to the axial direction A. Therefore, the radial plane E is the plane which is perpendicular to the axial direction A and contains the line E.

[0078] The radial plane E is the plane in which the magnetically active core 31 of the rotor 3 is actively magnetically suspended between the end faces 271 in the stator 2 in the operating state. If the rotor 3 is not tilted and is not deflected in the axial direction A, the magnetic center plane lies in the radial plane E. The radial plane E defines the xy plane of a Cartesian coordinate system, the z axis of which extends in the axial direction A.

[0079] The radial position of the magnetically active core 31 or of the rotor 3 refers to the position of the rotor 3 in the radial plane E.

[0080] As it is sufficient for understanding the present invention, Figure 1 The rotor 3 in the figure shows only the magnetically active core 31. It is to be understood that the rotor 3 can of course also include further components, such as a sheath or an encapsulation, which is preferably made of plastic, metal or a metal alloy or ceramic or a ceramic material. In addition, the rotor 3 can also include blades for mixing, stirring or pumping the fluid (see for example Fig.12 ) or other components.

[0081] When the rotor 3 is inserted into the cup-shaped recess 211 of the receiving pot 21, the rotor 3 and in particular the magnetically active core 31 of the rotor 3 are surrounded by the radially outwardly arranged end faces 271 of the transverse legs 27 of the coil core 25 of the stator 2. Thus, the transverse legs 27 form a plurality of distinct stator poles, in this case six stator poles. The transverse legs 27 are arranged at the upper ends of the longitudinal legs 26 and in the radial plane E. Each transverse leg 27 extends in the radial direction toward the rotor 3.

[0082] When the magnetically active core 31 of the rotor 3 is in its desired position during operation, the magnetically active core 31 is centered between the end faces 271 of the transverse legs 27, so that the transverse legs 27 arranged in the radial plane E are also located in the magnetic center plane. According to the illustration, the concentrated windings 61 are arranged below the radial plane E and are aligned so that their coil axes extend in the axial direction A.

[0083] All first ends 261 of the longitudinal legs 26 - that is, according to the diagram ( Figure 1 ) are connected to each other by the back iron 22. Preferably, the back iron 22 is designed in an annular manner. Such embodiments are possible (see, for example, Figure 1 ), wherein the back iron 22 extends radially inward along all first ends 261 of the longitudinal legs 26.

[0084] In order to generate the electromagnetic field required for magnetically levitating the rotor 3 and optionally generating a torque on the rotor 3 , the longitudinal legs 26 of the coil core 25 carry windings designed as concentrated windings 61 .

[0085] In the operating state, these concentrated windings 61 are used to generate electromagnetic rotating fields, with which any adjustable transverse forces in the radial direction can be exerted on the rotor 3, so that the radial position of the rotor 3 can be actively controlled or adjusted, that is, its position in a radial plane E perpendicular to the axial direction A. Optionally, these electromagnetic rotating fields can also be used to generate a torque on the rotor 3.

[0086] The “magnetically active core 31 ” of the rotor 3 refers to the region of the rotor 3 that magnetically interacts with the stator 2 for generating a magnetic levitation force and optionally for generating a torque.

[0087] As already mentioned, in this embodiment, the magnetically active core 31 is designed in an annular manner. Furthermore, the magnetically active core 31 is designed in a permanent magnetic manner. For this purpose, the magnetically active core 31 may include at least one permanent magnet, but may also include several permanent magnets, or—as in the embodiment described here—completely consist of permanent magnetic material, so that the magnetically active core 31 is a permanent magnet. For example, the magnetically active core 31 is magnetized in the radial direction.

[0088] Those ferromagnetic or ferrimagnetic materials which are magnetically hard (i.e. which have a high coercive field strength) are typically referred to as permanent magnets. The coercive field strength is the magnetic field strength required to demagnetize the material. Within the framework of this application, a permanent magnet is understood to be a component or material having a coercive field strength (more precisely, a magnetic polarization coercive field strength) of greater than 10'000 A / m.

[0089] Such an embodiment is also possible in which the magnetically active core 31 is designed without permanent magnets, i.e. without permanent magnets. The rotor 3 is then designed, for example, as a reluctance rotor. The magnetically active core 31 of the rotor 3 is then made, for example, of a soft magnetic material. Suitable soft magnetic materials for the magnetically active core 31 are, for example, ferromagnetic or ferrimagnetic materials, i.e. in particular iron, nickel-iron, cobalt-iron, silicon-iron, mu metal.

[0090] Furthermore, embodiments are possible in which the magnetically active core 31 of the rotor 3 comprises both ferromagnetic material and permanent magnetic material. For example, permanent magnets may be placed or inserted into a ferromagnetic matrix. Such embodiments are advantageous, for example, if one wishes to reduce the cost of a large rotor by saving permanent magnetic material.

[0091] Embodiments are also possible in which the rotor is designed according to the principle of a cage rotor.

[0092] Both the annular back iron 22 and the coil core 25 of the stator 2 are each made of a soft magnetic material because they serve as magnetic flux conducting elements to conduct magnetic flux.

[0093] Suitable soft magnetic materials for the coil core 25 and the back iron 22 are, for example, ferromagnetic or ferrimagnetic materials, i.e. in particular iron, nickel iron, cobalt iron, silicon iron or mu metal. In this case, a design as a stack of stator sheets is preferred for the stator 2, wherein the coil core 25 and the back iron 22 are designed as metal sheets, i.e. they consist of several stacked thin metal sheet elements.

[0094] Furthermore, it is possible that the coil core 25 and the back iron 22 can be composed of particles of the above-mentioned materials which are pressed and then sintered. The metal particles are preferably embedded in a plastic matrix so that they are at least partially insulated from each other, whereby eddy current losses can be minimized. Therefore, soft magnetic composites consisting of electrically insulating and compressed metal particles are also suitable for use in stators. In particular, these soft magnetic composites, which are also named SMC (soft magnetic composites), can be composed of iron powder particles coated with an electrically insulating layer. These SMCs are then formed into the desired shape by means of a powder metallurgy process.

[0095] During operation of the magnetic levitation device 1, the magnetically active core 31 of the rotor 3 interacts with the stator 2 so that the rotor 3 can be magnetically suspended relative to the stator 2 without contact and preferably can also be magnetically rotated around the axial direction A without contact. In this case, it is particularly advantageous that the same winding 61 with which the magnetic levitation of the rotor 3 is achieved is also used to generate a torque on the rotor 3. Preferably, three degrees of freedom of the rotor 3 can be actively adjusted, namely its position in the radial plane E and its rotation. With respect to its axial deflection from the radial plane E in the axial direction A, the magnetically active core 31 of the rotor 3 is passively magnetically stabilized by magnetic resistance, i.e. it cannot be controlled. With respect to the remaining two degrees of freedom, the magnetically active core 31 of the rotor 3 is also passively magnetically stabilized, i.e. tilted relative to the radial plane E perpendicular to the desired axis of rotation. By the interaction of the magnetically active core 31 with the coil core 25, the rotor 3 is thus passively magnetically suspended or passively magnetically stabilized in the axial direction A and prevented from tilting (three degrees of freedom in total), and actively magnetically suspended in the radial plane (two degrees of freedom).

[0096] This is generally the case, and active magnetic suspension is also referred to within the framework of this application as actively controllable or adjustable magnetic suspension, for example by means of an electromagnetic field generated by concentrated windings 61. Passive magnetic suspension or passive magnetic stabilization is not controllable or adjustable. Passive magnetic suspension or stabilization is based, for example, on magnetic resistance forces, which bring the rotor 3 back to its desired position again when the rotor 3 deviates from its desired position (i.e., for example, when it is displaced or deflected in the axial direction A or when it tilts).

[0097] In contrast to classical magnetic bearings, in the magnetic levitation device 1, magnetic levitation—and optionally the generation of a torque acting on the rotor—is achieved with the aid of an electromagnetic rotating field. In order to generate a magnetic levitation force and a torque for rotating the rotor 3 about the axial direction A in combination, it is possible—for example Figure 1 As shown in FIG. 2 , exactly one concentrated winding 61 is arranged on each longitudinal leg 26 .

[0098] On the other hand, embodiments are possible in which two different winding systems are provided for the combined generation of magnetic levitation forces and torque for rotating the rotor 3. For this purpose, for example, exactly two concentrated windings are arranged in each case at each longitudinal leg, which are arranged adjacent to one another with respect to the axial direction A. One of the two windings belongs to the first of the two winding systems and the other belongs to the second of the two winding systems.

[0099] exist Figure 1 In the embodiment presented in FIG. 1 with exactly one concentrated winding 61 per coil core 25 , the values ​​for the current required for suspension and the current required for generating torque, which are determined in each case, for example, in the control unit 40 , are added or superimposed by calculation—for example with the aid of software. The resulting total current is then applied to the respective concentrated winding 61 .

[0100] For better understanding, Figure 3 The back iron 22 is presented separately from the coil core 25. The back iron 22 is designed essentially in an annular manner and extends radially inwardly along the first end 261 of the longitudinal leg 26 in the assembled state (see also Figure 1 ). Preferably, the back iron 22 is of sheet metal design. In the sheet metal embodiment, the back iron 22 is made of a plurality of thin elements which are stacked parallel to each other in the axial direction. All elements are designed identically, in this case substantially annular, and also have the same thickness in each case.

[0101] On its radially outer circumferential surface, the back iron 22 has a plurality of flats 222 which are designed in a planar form, i.e. are not curved. In the assembled state of the stator 2, the first end 261 of one of the longitudinal legs 26, which preferably has a rectangular contour, rests in each case on each of these flats 222. Due to the planar design of the flats 222, a large contact surface between the back iron 22 and the longitudinal legs 26 of the coil core 25 is ensured, resulting in particularly good flux conduction or very low magnetic resistance at the transition between the back iron 22 and the longitudinal legs 26. The flats can also be arranged at the individual segments 225, wherein the individual segments 225 are arranged in a groove in the back iron 22. The size of the groove is designed so that the individual segments 225 are flush with the rest of the back iron 22.

[0102] Preferably, the number of the flat portions 222 is the same as the number of the coil cores 25 , that is, six flat portions 222 are provided here, and these flat portions 222 are equidistantly distributed along the outer periphery of the back iron 22 .

[0103] Furthermore, one or more ventilation holes or ventilation recesses 223 may be provided at the back iron 22 , which extend completely through the back iron 22 with respect to the axial direction A. Air may escape through the ventilation recesses 223 , for example when filling the housing 20 with a heat-conductive potting compound.

[0104] In order to determine the current position of the rotor 3 in the cup-shaped recess 211, the magnetic levitation device 1 comprises a plurality of—here six—magnetic field sensors 8 (see also Figure 7 ), which is arranged around the cup-shaped recess 211 in the assembled state of the magnetic levitation device 1. The magnetic field sensor 8 is a sensor that can measure a magnetic field. In particular, the following types of sensors are suitable as magnetic field sensor 8: Hall sensor or magnetoresistive sensor or GMR sensor (GMR: Giant Magnetoresistive). With the help of the magnetic field sensor 8, the current position of the rotor 3 in the cup-shaped recess 211 of the receiving tank 21 or in the radial plane E can be determined in a manner known per se.

[0105] according to Figure 7 In the particularly preferred embodiment presented therein, all magnetic field sensors 8 are arranged on a circuit board 7 and are signal-connected thereto via an electrical connection 81, so that all magnetic field sensors 8 can be controlled via the circuit board 7, and the signals measured by the magnetic field sensors 8 can be received and processed via the circuit board 7, or transmitted to the control device 40, for example.

[0106] The circuit board 7 is arranged with respect to the axial direction A between the winding 61 on the one hand and the transverse leg 27 on the other hand. Figure 7 Also present in the figure is a holding device 9 which is designed to receive a circuit board 7. Preferably, the circuit board 7 can be attached to the holding device 9, for example by means of a plurality of screws 75 (see Fig. 9 ).

[0107] The circuit board 7 is preferably designed as an electronic printed circuit board or PCB (printed circuit board). The magnetic field sensor 8 and the electrical connection 81 are attached to the circuit board 7, for example by means of a solder connection. In addition, components for controlling the magnetic field sensor and / or for evaluating the measurement signal determined by the magnetic field sensor 8 can be arranged on the circuit board 7.

[0108] The circuit board 7 is designed substantially in an annular manner and is arranged parallel to the radial plane E. Figure 7As can be seen in the figure, the circuit board 7 is not designed as a closed loop, but has a ring segment-shaped opening 74, so that the circuit board 7 has two ends when viewed in the circumferential direction. Preferably, the circuit board 7 is arranged radially inside relative to the longitudinal legs 26 of the coil core 25, so that the magnetic field sensors 8 are arranged around the cup-shaped recess 211 of the accommodating pot 21. It is particularly preferred that the magnetic field sensors 8 are arranged equidistantly on the circuit board 7 relative to the circumferential direction.

[0109] The circuit board 7 further comprises an electrical connection element 76, which connects the circuit board 7 to the control device 40, so that the control device 40 and the circuit board 7 can exchange voltage or current via the electrical connection element 76. The electrical connection element 76 is preferably designed as a flexible printed circuit board. Of course, the electrical connection element 76 can also be designed in different ways, such as a cable, a cable bundle or a flat ribbon cable.

[0110] As already mentioned, the magnetic levitation device 1 also comprises a holding device 9. The holding device 9 serves for particularly simple but precise mounting of the magnetic levitation device 1 and for very precise positioning of the magnetic field sensor 8 relative to the cup-shaped recess 211 in which the rotor 3 is arranged in the operating state.

[0111] In the following, the holding device 9 will be explained with reference to several figures. Figure 5 The holding device 9 is shown in a perspective illustration, wherein the viewing direction is from the direction of the first end 261 of the longitudinal leg 26. Figure 1 In the illustration in FIG. , the view is directed from below toward the holding device 9 . Figure 6 The holding device 9 is shown in a perspective view, wherein the viewing direction is Figure 5 The observation direction is opposite. Figure 1 The diagram in Figure 6 The view in FIG. 8 is therefore from above toward the holding device 9 . Figure 5 and Figure 6 Both show a holding device 9 , wherein a printed circuit board 7 is arranged in the holding device 9 . Figure 8 A cross-sectional view of a holding device 9 with a circuit board 7 inserted therein is shown. For a better understanding, Fig. 9 It also shows that Figure 8 Enlarged illustration of detail I.

[0112] The holding device 9 is designed essentially in a plate-shaped and annular manner and comprises several recesses 91 for receiving the transverse legs 27 of the coil cores 25. Exactly one recess 91 is provided for each transverse leg 27, so that the number of recesses 91 is equal to the number of coil cores 25. The holding device 9 is inserted into the receiving pot 21 (see Figure 1 ) and extends from the bottom of the container 21 along the axial direction A to the bottom of the container 21 according to the diagram ( Figure 1 ) which, according to the illustration, is arranged above the winding 61 relative to the axial direction A.

[0113] The holding device 9 is designed in an annular manner such that it can be arranged around the cup-shaped recess 211 of the receiving pot 21 , ie the cup-shaped recess 211 is radially surrounded on the outside by the holding device 9 .

[0114] The holding device 9 has an axial edge region 92 which has an outer diameter which is smaller than the diameter of the rest of the holding device 9. Figure 6 , the axial edge region 92 is the upper axial edge region. With respect to the axial direction A, the axial edge region 92 ends at a projection 93, at which the outer diameter of the second retaining device 9 increases. The embodiment with the axial edge region 92 and the projection 93 of smaller diameter serves to ensure that the receiving tank 21 can radially surround the retaining device 9 on the outside. This is particularly true in Figure 1 The receiving pot 21 has a radial outer edge 212 which, in the assembled state, surrounds the axial edge region 92 of the second retaining device 9. The radial outer edge 212 is designed to be longer relative to the axial direction A so that it extends at most as far as the projection 93.

[0115] The holding device 9 is preferably made of plastic, and particularly preferably of a plastic that can be processed by injection molding. Therefore, the holding device 9 is preferably designed as an injection molded part. Suitable plastics for making the holding device 9 are, for example, acrylonitrile butadiene styrene (ABS), polyamide (nylon, PA), polypropylene (PP) or fiber-filled polypropylene.

[0116] The holding device 9 serves both as a holder for the circuit board 7 and as a holder for the magnetic field sensor 8, with which the magnetic field sensor 8 can be placed very precisely relative to the cup-shaped recess 211. For this purpose, a cavity 95 is provided in the holding device 9 for each magnetic field sensor 8, which cavity is delimited by an inner wall 951 and by an outer wall 952 with respect to the radial direction, wherein the magnetic field sensor 8 can be pushed into the cavity 95 and wherein the cavity 95 is dimensioned such that the inner wall 951 and the outer wall 952 lie flat against the magnetic field sensor 8. This can be achieved in the case of a plurality of magnetic field sensors 8, e.g., a plurality of magnetic field sensors 8 having ... Fig. 9 Best seen in.

[0117] Here, an important aspect is that both the inner side wall 951 and the outer side wall 952 of the cavity 95 lie flat against the magnetic field sensor 8, because this means that the position of the magnetic field sensor 8 relative to the cup-shaped recess 211 is known with very high accuracy. The magnetic field sensor 8 is preferably designed in a rectangular manner. The cavity 95 is dimensioned so that the magnetic field sensor 8 can be completely inserted into the cavity 95 relative to the axial direction A. Therefore, the cavity 95 forms a recess for the magnetic field sensor 8, the depth of which relative to the axial direction A is at least as deep as the extension of the magnetic field sensor 8 in the axial direction A. The width of the recess in the radial direction (i.e. the distance measured in the radial direction between the inner side wall 951 and the outer side wall 952) is dimensioned so that it corresponds to the extension of the magnetic field sensor 8 in the radial direction, so that the magnetic field sensor 8 can be pushed into the cavity 95 in the axial direction, and the inner side wall 951 and the outer side wall 952 of the cavity 95 then lie flat against the magnetic field sensor 8.

[0118] Due to this embodiment in which the magnetic field sensor 8 is surrounded on three sides by the cavity 95 , on the one hand the position of the magnetic field sensor 8 is known with very high accuracy and on the other hand the magnetic field sensor 8 arranged in the cavity 95 is also very well protected.

[0119] In order to facilitate the insertion of the magnetic field sensor 8 into the cavity 95 during assembly, the inner wall 951 and / or the outer wall 952 may be designed to be slightly inclined relative to the axial direction, so that when viewed in the axial direction A, the cavity 95 is designed to be slightly conical, whereby the cavity 95 is slightly conical relative to the axial direction. Fig. 9 The icons in the figure taper upward.

[0120] Furthermore, it is preferred that each magnetic field sensor 8 is arranged as close as possible to the cup-shaped recess 211. For this purpose, the inner diameter of the holding device 9 is set to be equal to the outer diameter DA ( Fig.11 ) are the same or only slightly larger. Then, in the assembled state, the wall of the holding device 9, which forms the inner wall 951 of the cavity 95, bears against the cup-shaped recess 211 of the receiving pot 21. Thus, viewed in the radial direction, the inner wall 951, which delimits the cavity 95, is arranged in each case between the cup-shaped recess 211 of the receiving pot 21 and the magnetic field sensor 8.

[0121] Since the magnetic field sensors 8 are preferably arranged equidistantly on the circuit board 7 with respect to the circumferential direction, the six cavities 95 for the six magnetic field sensors 8 are also preferably arranged equidistantly with respect to the circumferential direction of the holding device 9. Particularly preferably, exactly one cavity 95 is arranged in each case between two recesses 91 adjacent in the circumferential direction. In the assembled state, each magnetic field sensor 8 is then arranged in each case between two coil cores 25 adjacent in the circumferential direction.

[0122] With regard to the highest possible accuracy of the position of magnetic field sensor 8 relative to cup-shaped recess 211 , a preferred measure is to provide in each case for each cavity 95 a separate guide element 96 which forms an inner side wall 951 or outer side wall 952 delimiting cavity 95 .

[0123] exist Fig. 9 , an embodiment is shown in which the guide element 96 forms the outer side wall 952 of the cavity 95. For a better understanding, Fig.10 Still showing Fig. 9 95 . Since such a separate guide element 96 is provided for each cavity 95 , there are six such guide elements 96 in this exemplary embodiment. The separate guide elements 96 are separate components, i.e. components separate from the holding device 9 , which are pushed into the holding device 9 only after the holding device 9 has been manufactured in order to thereby form the cavity 95 for the magnetic field sensor 8 . Since the guide elements 96 are separate components, they can be manufactured with very high precision, which is advantageous for the accuracy of the position of the magnetic field sensor 8 . In addition, the separate guide elements 96 make it particularly easy to adapt the dimensions of the cavity 95 to the corresponding magnetic field sensor 8 .

[0124] As in Fig. 9 As can be best seen in FIG. 1 , each individual guide element 96 has an L-shaped profile. The individual guide element 96 has a bottom 961 ( Fig.10 ), which forms the short leg of L; and a side wall 962, which forms the long leg of L. The bottom 961 of the guide element 96 also forms the bottom of the cavity 95. The side wall 962 of the guide element 96 forms the outer side wall 952 which delimits the cavity 95. The side wall 962 comprises two parallel guides 963, between which the magnetic field sensor 8 is pushed when the guide element 96 is inserted into the holding device 9. The two parallel guides 963 have a distance D1 between each other, which corresponds to the corresponding extension of the magnetic field sensor 8, so that the magnetic field sensor 8 can be pushed between the two guides 963 and guided by the guides 963 in the process. The two guides 963 have a length L, which in the inserted state is the extension of the guides 963 in the axial direction. The length L is dimensioned so that it is at least as large as the corresponding dimension of the magnetic field sensor 8, so that the magnetic field sensor 8 does not protrude beyond the guide element 96 with respect to the axial direction A.

[0125] As already mentioned, in the embodiment described here, the holding device 9 is designed such that it can receive the circuit board 7 on which the magnetic field sensor 8 is arranged. For this purpose, the holding device 9 comprises an annular edge 97 ( Fig. 9), wherein the shoulder 98 is arranged radially inwardly relative to the edge 97. The shoulder 98 is designed and arranged such that the circuit board 7 can be placed on the shoulder 98 and rests on it. Optionally, the circuit board 7 can be attached to the shoulder 98 and thus to the holding device 9 by means of several screws 75. Preferably, the edge 97 is designed such that it protrudes beyond the circuit board 7 with respect to the axial direction A. This has the advantage that the entire holding device 9 can then be poured with a potting compound and the circuit board is completely covered by the potting compound.

[0126] As shown in cross section, Fig.11 The receiving pot 21 of the stator 2 of an embodiment of a magnetic levitation device is shown, whereby the cross section is taken in the axial direction A.

[0127] The holding tank 21 with the cup-shaped recess 211 is preferably designed as one piece. The holding tank 21 is preferably made of plastic, and is particularly preferably made of plastic that can be processed by injection molding. Therefore, the holding tank 21 is preferably designed as an injection molded part. Suitable plastics for making the holding tank 21 are, for example, acrylonitrile-butadiene-styrene (ABS), polyamide (nylon, PA), polypropylene (PP), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyimide (PI), polyetherketone, polysuccinimide (PSI), polyphthalamide (PPA) or polyetheretherketone (PEEK).

[0128] The receiving pot 21 comprises a cup-shaped recess 211 into which the rotor 3 can be inserted and a radial outer edge 212 which surrounds the axial edge region 92 of the holding device 9 in the assembled state.

[0129] In the following, it will be explained how the magnetic levitation device can be assembled in a very simple manner. For example, the assembly can be performed as follows. The circuit board 7 on which the magnetic field sensors 8 are arranged and attached is inserted into the holding device 9. For this purpose, each of the magnetic field sensors 8 is first pushed into one of the cavities 95, and then the circuit board 7 is placed on the shoulder 98 of the holding device 9. Optionally, the circuit board 7 is attached to the holding device 9 by means of a screw 75.

[0130] Subsequently, the first potting compound is completely poured into the holding device 9 so that the circuit board 7 is completely covered by the first potting compound. The first potting compound is preferably a soft potting compound. A soft potting compound refers to a potting compound with a Shore hardness D of less than 40. For example, silicone or polyurethane are suitable as the first potting compound. During operation of the magnetic levitation device 1, strong and frequent temperature fluctuations may occur, in particular in the area of ​​the holding device 9 in which the magnetic field sensor 8 is arranged. Soft potting compounds are more resistant to such fluctuations. Therefore, soft potting compounds are preferably used for potting the holding device 9.

[0131] The coil core 25 passes through the recess 91 in the holding device 9 and through the concentrated winding 61. The magnetic back iron 22 is arranged between the first ends 261 of the longitudinal legs 26. The holding device 9, the back iron 22 and the coil core 25 with the concentrated winding 61 arranged thereon are arranged in a first installation direction along the axial direction A (according to Figure 2 , from the left) into the stator housing 101 of the housing 10. In the process, the electrical connection element 76 is passed through the stator housing 101 into the control housing 102 parallel to the longitudinal legs 26 of the coil core 25.

[0132] When the retaining device 9, the winding 61, the back iron 22 and the coil core 25 are arranged in the stator housing 101 of the housing 10, the accommodating pot 21 is placed on the housing 10 and connected to the housing 10 in a sealed manner (preferably an airtight sealed manner), whereby the seal 201 is arranged between the accommodating pot 21 and the housing 10.

[0133] Subsequently, the housing 10 of the magnetic levitation device 1 is potted with a heat-conducting potting compound. Preferably, a second potting compound is used for this purpose, which is heat-conducting and different from the first potting compound. The second heat-conducting potting compound is preferably harder than the first potting compound. The second heat-conducting potting compound should have particularly good thermal conductivity in order to quickly and reliably dissipate the heat generated in the operating state into the housing and then dissipate the heat from the housing mainly by convection. For example, polyurethane, epoxy resin, acrylic resin or polyester are suitable as the second heat-conducting potting compound.

[0134] After the second potting compound is poured into the stator housing 101 of the housing 10, the control unit 40 is inserted into the control housing 102 of the housing 10 along a second installation direction, wherein the second installation direction is opposite to the first installation direction. Figure 2 , the control unit 40 is therefore inserted into the control housing 102 from the right. The electrical connection element 76 is connected to the control unit 40.

[0135] When the control unit 40 is arranged in the control housing 102 of the housing 10, the housing cover 11 is placed on the housing 10 and connected to the housing 10 in a sealed manner, preferably a gas-tight manner, wherein the sealing element 105 is arranged between the housing cover 11 and the housing 10. The housing cover 11 is attached to the housing 10, for example by means of several screws 111 ( Figure 1 ).

[0136] Optionally, for example for applications with highly corrosive or erosive or explosive fluids, the control housing 102 of the housing 10 may also be potted with a potting compound. If the control housing is also potted, this is done before the housing cover 11 is placed on the housing 10 and securely connected to it.

[0137] In addition, the present invention provides a centrifugal pump 100 for conveying a fluid, characterized in that the centrifugal pump 100 comprises a magnetic levitation device 1 and a rotor 3, wherein the magnetic levitation device 1 is designed according to the present invention. The magnetic levitation device 1 is designed so that in addition to the non-contact magnetic levitation of the rotor 3, it can generate a torque acting on the rotor 3, which drives the rotor 3 to rotate around the axial direction A.

[0138] Fig.12 An embodiment of a centrifugal pump according to the invention is shown in a schematic sectional illustration in section along the axial direction A, which is designated in its entirety by the reference symbol 100. For better understanding and for reasons of a better overview, Fig.12 The housing 10 and the containing tank 21 are not shown.

[0139] The centrifugal pump 100 comprises a pump unit 50 having a pump housing 51, which comprises an inlet 52 and an outlet 53 for the fluid to be conveyed, wherein the rotor 3 is arranged in the pump housing 51 and comprises a plurality of blades 54 for conveying the fluid. The pump unit 50 is designed such that the pump unit 50 can be inserted into the receiving pot 21 of the stator 2 so that the magnetically active core 31 of the rotor 3 is surrounded by the end faces 271 of the transverse legs 27.

[0140] Advantageously, the rotor 3 is designed as an integral rotor, because it is both the magnetically suspended rotor 3 and the rotor 3 of the centrifugal pump 100 that uses it to convey fluid. This embodiment as an integral rotor offers the advantage of a very compact and space-saving design.

[0141] The stator 2 is arranged in the housing 10 ( Fig.12 In the embodiment of the present invention, the housing 10 is preferably designed as a hermetically sealed housing 10 together with the receiving tank 21. The control unit 40 is preferably, but not necessarily, also arranged in the housing 10. The housing 10 is preferably filled with a potting compound (for example, with epoxy resin, acrylic resin, polyester or polyurethane), so that all components arranged inside the housing 10 are surrounded by the potting compound.

[0142] The pump unit 50 is arranged in the cup-shaped recess 211 of the storage tank 21 ( Fig.12 ), so that the rotor 3 arranged in the pump housing 51 is surrounded by the cup-shaped recess 211 , wherein the magnetically effective core 31 of the rotor 3 is arranged between the transverse legs 27 of the coil core 26 .

[0143] The pump housing 51 is preferably fixed to the stator housing 20 by means of a plurality of screws (not shown).

[0144] The rotor 3 comprises a plurality of blades 54 for conveying a fluid. For example, in the embodiment described here, a total of four blades 54 are provided, whereby this number has exemplary characteristics. The rotor 3 also comprises a sheath 38, and the magnetically effective core 31 of the rotor 3 is surrounded by the sheath 38 and is preferably hermetically sealed so that the magnetically effective core 31 of the rotor 3 does not come into contact with the fluid to be conveyed. All blades 54 are arranged on the sheath 38 and are arranged equidistantly relative to the circumferential direction of the rotor 3. Each blade 54 extends outwardly in the radial direction and is connected to the sheath 38 in a torque-proof manner. The blades 54 may be separate components, which are then fixed to the sheath 38. Of course, it is also possible that all blades 54 are components of the sheath 38, that is, the sheath 38 is designed as one piece with all blades 54. The rotor 3 with the blades 54 forms a wheel or impeller of the centrifugal pump 100, with which one or more fluids act on it.

[0145] Depending on the application, it is preferred if the pump housing 51 of the pump unit 50 as well as the jacket 38 and the blades 54 are made of one or more plastics. Suitable plastics are: polyethylene (PE), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), polyurethane (PU), polyvinylidene fluoride (PVDF), acrylonitrile butadiene styrene (ABS), polyacrylate, polycarbonate (PC), polyether ether ketone (PEEK) or silicone. For many applications, materials with the brand names Teflon, polytetrafluoroethylene (PTFE) and perfluoroalkoxy polymers (PFA) are also suitable as plastics.

[0146] It is to be understood that the magnetic levitation device 1 according to the present invention is also suitable for use in devices other than centrifugal pumps, such as mixing devices for mixing flowable substances, for stirring devices (for example for mixing fluids in a tank), for fans, or also for devices for supporting and rotating wafers (for example in semiconductor production).

Claims

1. A magnetic suspension device for non-contact magnetic suspension of a rotor (3), the rotor (3) comprising a disc-shaped or annular magnetic active core (31), wherein: The magnetic levitation device has a stator (2), the stator (2) comprising a plurality of coil cores (25), each of the coil cores (25) comprising a longitudinal leg (26) extending from a first end (261) to a second end (262) in an axial direction (A), and a transverse leg (27) arranged at the second end (262) of the longitudinal leg and extending in a radial direction perpendicular to the axial direction (A), wherein at least one concentrated winding (61) is provided at each longitudinal leg (26), the winding surrounding the corresponding longitudinal leg (26), wherein the stator (2) further comprises a cup-shaped recess (211), wherein the rotor (3) can be inserted into the cup-shaped recess (211), wherein the cup-shaped recess (211) is arranged at the stator (2). At the axial end, wherein the transverse legs (27) are arranged around the cup-shaped recess (211), and wherein a plurality of magnetic field sensors (8) for determining the position of the rotor (3) are arranged around the cup-shaped recess (211), characterized in that an annular retaining device (9) is provided for the magnetic field sensor (8), the annular retaining device (9) having a cavity (95) for each magnetic field sensor (8), the cavity being delimited by an inner wall (951) and by an outer wall (952) relative to the radial direction, wherein the magnetic field sensor (8) can be pushed into the cavity (95), and wherein the cavity (95) is sized so that the inner wall (951) and the outer wall (952) lie flat against the magnetic field sensor (8).

2. The magnetic levitation device according to claim 1, wherein: A circuit board (7) is arranged between the winding (61) and the transverse leg (27) relative to the axial direction (A), all magnetic field sensors (8) are arranged on the circuit board, and a second holding device (9) is designed to receive the circuit board (7).

3. The magnetic levitation device according to claim 2, wherein: The holding device (9) has an annular edge (97) on which a shoulder (98) is provided, wherein the shoulder (98) is arranged radially inwardly relative to the edge (97) and wherein the circuit board (7) rests on the shoulder (98).

4. The magnetic levitation device according to claim 3, wherein: The edge (97) is designed such that it protrudes beyond the circuit board (7) with respect to the axial direction (A).

5. A magnetic levitation device according to any one of the preceding claims, wherein: The holding device (9) has a separate recess (91) for each coil core (25), which recess surrounds the coil core (25) and receives a transverse leg (27) of the coil core (25).

6. The magnetic levitation device according to claim 5, wherein: Each cavity (95) is arranged between two adjacent recesses (91) with respect to the circumferential direction.

7. The magnetic levitation device according to claim 1, wherein exactly six coil cores (25) are provided in the magnetic levitation device.

8. Magnetic levitation device according to any of the preceding claims, comprising exactly six magnetic field sensors (8), which are preferably arranged equidistantly around the cup-shaped recess (211).

9. The magnetic levitation device according to any one of claims 2 to 8, wherein: The holding device (9) is filled with a first potting compound such that the circuit board (7) is completely covered by the potting compound.

10. A magnetic levitation device according to any one of the preceding claims, wherein: A separate guide element (96) is provided in each case for each cavity (95), said guide element forming the inner side wall (951) or the outer side wall (952) by which said cavity (95) is delimited.

11. A magnetic levitation device according to any one of the preceding claims, wherein: The stator (2) has a receiving pot (21), which forms an axial end of the stator (2), wherein the receiving pot (21) has the cup-shaped recess (211), the rotor (3) can be inserted into the cup-shaped recess (211), and wherein the receiving pot (21) radially outwardly surrounds the second retaining device (9).

12. The magnetic levitation device according to any one of the preceding claims, comprising a housing (10), the housing (10) comprising a stator housing (101) and a control housing (102) arranged adjacent to each other with respect to the axial direction (A), wherein: The stator housing (101) is designed to receive the coil core (25) on which the concentrated winding (61) is arranged, and the control housing (102) is used to receive a control unit (40) for controlling the winding (61) and supplying electrical energy to the winding (61) for generating an electromagnetic field.

13. The magnetic levitation device according to claim 12, wherein: The housing (10) is designed so that the coil core (25) on which the concentrated winding (61) is arranged can be inserted into the stator housing (101) in a first installation direction along the axial direction (A), and the control unit (40) can be inserted into the control housing (102) in a second installation direction, wherein the first installation direction points in a direction opposite to the second installation direction.

14. A magnetic levitation device according to any one of the preceding claims, wherein: The stator (2) is designed to generate a torque, with which the rotor (3) can be driven magnetically without contact for rotation about the axial direction (A).

15. A centrifugal pump for conveying fluid, characterized in that: The centrifugal pump comprises a magnetic levitation device (1) according to claim 14, and a rotor (3) with a magnetically active core (31), wherein the rotor (3) can be inserted into a cup-shaped recess (211) of a receiving tank (21), and wherein the rotor (3) is designed as a rotor (3) of the centrifugal pump.

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