Pump unit for centrifugal pump and centrifugal pump

Abstract

The invention relates to a pump unit for a centrifugal pump and a centrifugal pump. The invention relates to a pump unit for a centrifugal pump, comprising a pump unit and a stator extending axially from a first axial end to a second axial end, a cup-shaped recess being provided at the first axial end, the pump unit being insertable into the cup-shaped recess, the pump unit having a pump housing having an inlet and an outlet, and a rotor in the pump housing, the invention relates to a pump unit comprising a rotor having a plurality of vanes and rotatable in the axial direction, the pump unit being designed for contactless magnetic levitation and magnetic drive of the rotor by means of a stator, the vanes being arranged around a central inlet region of the rotor, the rotor comprising at least one release opening for generating a recirculation flow, the flow being guided from a rear side of the rotor facing away from the inlet in the direction of the central inlet region, the rotor also has a separating element in the central inlet region, which redirects the recirculation flow in a radial direction perpendicular to the axial direction. The blades, the separating elements and the release openings of the rotor are designed as a single-piece unit. The invention further relates to a centrifugal pump for conveying a fluid, comprising such a pump unit.

Description

Technical Field

[0001] This invention relates to a pump unit for a centrifugal pump according to the preamble of an independent patent claim. The invention also relates to a centrifugal pump having such a pump unit. Background Technology

[0002] A centrifugal pump is known to include a pump unit and a stator, the stator being designed as a drive unit for the rotor of the pump unit, wherein the rotor of the pump unit forms the centrifugal wheel of the centrifugal pump. The rotor can be magnetically supported without contact and can be driven to rotate about the axial direction without contact by means of the stator in the pump unit. For example, the applicant uses... BPS Pumps is a product name for centrifugal pumps sold in this category.

[0003] The stator and rotor form an electromagnetic rotary drive. For example, in In BPS pumps, the electromagnetic rotary actuator is designed based on the principle of a bearingless motor. The term "bearingless motor" refers to an electromagnetic rotary actuator in which the rotor is fully magnetically supported relative to the stator, without individual magnetic bearings. For this purpose, the stator is designed as both a bearing and a drive stator, serving as both the stator of the electric actuator and the stator of the magnetic bearings. A rotating magnetic field is generated using the stator's electrical windings. On the one hand, this rotating magnetic field applies torque to the rotor, enabling its rotation about a desired axis of rotation defined by the axial direction. On the other hand, this rotating magnetic field applies an arbitrarily adjustable lateral force to the rotor, allowing its radial position to be actively controlled or adjusted. Therefore, three degrees of freedom of the rotor—its rotation and its radial position (two degrees of freedom)—can be actively adjusted. Regarding the other three degrees of freedom—the rotor's position in the axial direction and its tilt relative to a radial plane perpendicular to the desired axis of rotation (two degrees of freedom)—the rotor is passively magnetically supported or stabilized by magnetic reluctance, meaning it cannot be controlled. The rotor has a complete set of magnetic bearings without individual magnetic bearings, hence the name "bearingless motor." In this bearing and drive stator, the bearing function cannot be separated from the drive function.

[0004] Of course, other centrifugal pump designs are also known, in which the rotor is magnetically supported without contact, such as those centrifugal pumps that use separate magnetic bearings for the rotor, separating the magnetic bearing function from the drive function. For example, a separate coil is used for this purpose, which only provides the bearing force for the rotor but does not contribute to the drive of the rotor. Such a centrifugal pump is disclosed, for example, in WO2022 / 004144.

[0005] Centrifugal pumps with rotors that are supported and driven by non-contact magnetic force, such as those designed and operated based on the principles of bearingless motors, have proven themselves in numerous applications. Because they lack mechanical bearings, these centrifugal pumps are suitable for applications conveying highly sensitive substances, such as blood pumps, or applications requiring extremely high purity, such as those in the semiconductor, pharmaceutical, and biotechnology industries. They are also suitable for applications conveying abrasive or corrosive substances that would rapidly damage mechanical bearings, such as pumps used in the semiconductor industry for slurries, sulfuric acid, phosphoric acid, or other chemicals.

[0006] Figure 1 A view of a centrifugal pump 200', known from the prior art, is shown. This centrifugal pump is designed based on the principle of a bearingless motor. For example, this is... BPS pump. To better understand, in Figure 1 A section has been removed to expose the interior of the centrifugal pump 200'. The centrifugal pump 200' includes a stator 100' and a pump unit 1'.

[0007] For example, EP 2 273 124 A1 discloses a pump unit 1' suitable for this type of centrifugal pump 200'. Figure 2 This pump unit 1' is shown in cross-section, where the section is formed along the axial direction A.

[0008] To show Figure 1 , Figure 2 The reference numerals in the figures refer to devices derived from the prior art, and each reference numeral is marked with quotation marks or dashes. Centrifugal pumps are generally indicated by reference numeral 200'.

[0009] Rotor 10' is arranged in pump unit 1', forming a centrifugal wheel or impeller for conveying fluid. Stator 100' has a stator housing 130' and extends along axial direction A from a first axial end 110' to a second axial end 120', wherein a cup-shaped recess 121' is provided at the first axial end 110', into which pump unit 1' can be inserted. Stator 100' together with rotor 10' forms an electromagnetic rotary actuator for rotating rotor 10' about axial direction A. Stator 100' is designed according to the principle of bearingless motors to provide a non-contact magnetic bearing for rotor 10'. For this purpose, the stator 100' is designed as a bearing and driver stator, by which the rotor 10' can be magnetically driven relative to the stator 100' to rotate about the axial direction A in a non-contact manner, and can be magnetically supported in a non-contact manner, wherein the rotor 10' is passively magnetically stable relative to the axial direction A, and is actively magnetically supported in a radial plane perpendicular to the axial direction A, which is composed of Figure 1 Line E in the diagram represents the line.

[0010] The electromagnetic rotary drive, with a stator 100' and a rotor 10', is designed as a so-called temple motor. The stator 100' includes multiple coil cores 125', here eight coil cores 125', each of which includes: a longitudinal leg 126', which extends from the first end (at... Figure 1 The coil core 126' extends axially along direction A to the second end (as shown in the diagram); and a transverse leg 127' is arranged at the second end of the longitudinal leg 126' and lies in the radial plane E. Each transverse leg 127' extends radially toward the rotor 10' from the associated longitudinal leg 126' and is defined by a radially inwardly positioned end face. The coil core 126' is arranged around the cup-shaped recess 121' relative to the circumferential direction, and thus around the rotor 10', such that the rotor 10' is arranged between the radially inwardly positioned end faces of the transverse legs 127' of the coil core 126'.

[0011] All the first ends of the longitudinal legs 126' are connected to each other via back iron 122' for conducting magnetic flux. At least one concentrated winding 160', 161' is provided at each longitudinal leg 126', which is arranged around the corresponding longitudinal leg 126'. Various variations are known regarding the number and arrangement of the concentrated windings 160', 161', which will not be explained in more detail here. For example, there are windings 160' that are wound around exactly one longitudinal leg 126' and windings 161' that are arranged around exactly two longitudinal legs 126'.

[0012] The multiple longitudinal legs 126' extend along the axial direction A and are reminiscent of temple pillars, hence the name Temple Motor.

[0013] Pump unit 1' (as known from EP 2 273 124 A1) Figure 2 The system includes: a pump housing 2' having an inlet 21' and an outlet 22' for the fluid to be conveyed; and a rotor 10' arranged within the pump housing 2' for conveying the fluid, the rotor being rotatable about an axial direction A. The rotor 10' includes a magnetically effective core 101' that magnetically cooperates with the stator 100' to generate torque and magnetic bearing force. For example, the magnetically effective core 101' is a permanent magnet ring or a permanent magnet disk.

[0014] The following design is also possible, in which the magnetically active core 101' is designed without permanent magnets, i.e., without permanent magnets. The rotor 10' is designed as, for example, a reluctance rotor. Thus, for example, the magnetically active core 101' of the rotor 10' is made of a soft magnetic material. For example, the soft magnetic material suitable for the magnetically active core 101' is a ferromagnetic or ferrimagnetic material, i.e., particularly iron, nickel-iron, cobalt-iron, silicon-iron, or μ metal.

[0015] Furthermore, it is also possible for the effective magnetic core 101' of the rotor 10' to include both ferromagnetic and permanent magnet materials. For example, permanent magnets can be placed or inserted into a ferromagnetic matrix. This design is advantageous, for example, if it is desirable to reduce the cost of a large rotor by saving permanent magnet material.

[0016] Typically, the active magnetic core 101' is completely encased in plastic. In other designs, the active magnetic core 101' is completely encapsulated in a sheath 102' made of ceramic or metallic materials (e.g., stainless steel, titanium, or tantalum).

[0017] In addition, the rotor 10' includes a plurality of blades 103' for conveying fluid from the inlet 21' to the outlet 22'.

[0018] The inlet 21' of the pump housing 2' is arranged and designed in such a way that the fluid to be transported flows toward the rotor 10' in the axial direction A. The outlet 22' extends parallel to the radial plane E, that is, extends substantially perpendicular to the inlet 21'.

[0019] The pump housing 2' includes a cylindrical cup 31' for receiving the rotor 10'. The cup 31' is inserted into a recess 121' in the stator housing 130', such that the rotor 10' (more precisely, the active magnetic core 101' of the rotor 10') is arranged between the transverse legs 127' of the coil core 126'.

[0020] For many applications, such as those in the semiconductor industry, pump unit 1' (excluding the magnetically active core 101') is made of plastic, such as perfluoroalkoxy polymer (PFA) or polytetrafluoroethylene (PTFE), because these materials are plastics with particularly high chemical resistance. These plastics are practically inert and cannot be corroded even by chemically aggressive substances, such as those frequently used in the semiconductor industry. Furthermore, PFA and PTFE are very pure plastics because they typically contain no additives, and their molecular composites are at least approximately inert. PFA is generally preferred because it can be processed in injection molding.

[0021] In centrifugal pump 200', where the fluid to be pumped is diverted from the axial direction A to the radial direction, rotor 10' is subjected to a strong load in the axial direction A. The axial thrust acting on the rotor is primarily caused by the pressure difference at rotor 10'. Although the suction pressure is substantially dominant on the side of rotor 10' facing inlet 21', there is a higher pressure on the rear side of rotor 10' because the rear side of the rotor is connected to outlet 22', where the delivery pressure is substantially dominant. The resulting axial thrust poses a challenge, especially in centrifugal pump 200' with rotor 10' having non-contact magnetic support. To avoid this axial thrust having to be received entirely by the axial magnetic bearings or stabilizing devices of rotor 10', various measures are known, such as a release opening 104' that extends along the axial direction A through the entire rotor 10' and thus forms a flow connection between the front and rear sides of rotor 10' facing inlet 21', resulting in pressure relief of rotor 10' relative to the axial direction A.

[0022] For example, EP 2 273 124 proposes dividing the blades 103' of rotor 10' into two centrifugal wheels by means of a separating element 7' aligned perpendicular to the axial direction A: a first centrifugal wheel 105' for generating the main flow HF' from inlet 21' to outlet 22'; and a second centrifugal wheel 106' for generating a recirculation flow RF', which is guided from the rear side of rotor 10' through release opening 104'. Figure 2 In the diagram, the main flow HF' is represented by a solid arrow HF', while the recirculation flow RF' is represented by a dashed arrow RF'. Each blade 103' is divided into a first blade 107' and a second blade 108' by a separating element 7'. The first blade 107' integrally forms the first centrifugal wheel 105', and the second blade 108' integrally forms the second centrifugal wheel 108'. The first blade 107' is arranged such that the central inlet region 25' of the rotor 10' has no blades 103'. The blades 103' are arranged around the central inlet region 25'.

[0023] The separating element 7', which separates the two centrifugal wheels 105' and 106' from each other, redirects the recirculated flow RF' from the axial direction A in the radial direction and at least partially separates the recirculated flow RF' from the main flow HF', preventing them from mixing directly with each other at the outlet of the release opening 104'. In this case, the separating element 7' extends radially into the blade 103', i.e., extends radially, and the separating element 7' overlaps with the blade 103'.

[0024] Even though this design with the separator element 7' has proven itself in practice, the manufacture of this rotor 10' is very complex and delicate. For example, the rotor 10' needs to be assembled from several separate parts. For the separator element 7', recesses must be provided in the blades 103' so that the separator element 7' can be inserted between the blades 103'.

[0025] For example, if pump unit 1' is made of plastic, the individual components must be connected to each other reliably and stably. This is done, for example, through welding processes. Besides time and cost factors, each welding process carries the risk of leakage at the weld joint, jeopardizing the operational reliability of the entire centrifugal pump 200'. There is also a risk of cracks or small gaps forming at the weld joint. Contaminants can accumulate there, then detach and contaminate the fluid being pumped during operation. In many applications, such as in the semiconductor industry, even the smallest impurities can have serious consequences; for example, they can render the final product unusable.

[0026] To ensure that the fluid-contacting components of rotor 10' (particularly the axial release opening 104' and the inner positioning edge below the separating element 7') function as intended, extremely high levels of precision and dimensional accuracy are required. In most cases, these components are manufactured using processes such as injection molding, where deviations from the predetermined target geometry are unavoidable. This results in protruding bumps or other deviations from the target geometry disrupting fluid flow and thus significantly impairing functionality. This means that these components, i.e., their individual parts, must be redone before assembly. If the components for rotor 10' have already been assembled, redoing is no longer possible because the corresponding redo tools are no longer sufficiently close to the areas of rotor 10' that require redoing. This means that, on the one hand, rotor 10', as known from the prior art, must be assembled from several separate parts, and on the other hand, additional working steps are required beyond the assembly of rotor 10' to enable it to function as intended. Summary of the Invention

[0027] Therefore, based on the prior art, one object of the present invention is to provide a pump unit with a rotor for a centrifugal pump, the rotor being magnetically levitated without contact, the pump unit being particularly simple in its manufacture and characterized by high operational reliability. Another object of the present invention is to provide a centrifugal pump having such a pump unit.

[0028] The subject matter of the invention that satisfies this purpose is characterized by the features of the independent patent claims.

[0029] Therefore, according to the present invention, a pump unit for a centrifugal pump is provided, the centrifugal pump including the pump unit and a stator extending axially from a first axial end to a second axial end, wherein a cup-shaped recess is provided at the first axial end, the pump unit being insertable into the cup-shaped recess, wherein the pump unit has: a pump housing having an inlet and an outlet for a fluid to be conveyed; and a rotor arranged in the pump housing having a plurality of blades for conveying the fluid, wherein the rotor is rotatable about the axial direction, wherein the pump unit is designed for non-contact magnetic levitation of the rotor by means of the stator and non-contact magnetic drive of the rotor, wherein the blades of the rotor are arranged around a central inlet region of the rotor, wherein the rotor includes at least one release opening for generating a recirculation flow guided from a rear side of the rotor away from the inlet along the direction of the central inlet region of the rotor, and wherein the rotor also has a partition element arranged in the central inlet region, the partition element redirecting the recirculation flow in a radial direction perpendicular to the axial direction. The rotor's plurality of blades, the separating element, and the at least one release opening are designed as single-piece units.

[0030] Because of the unit's monolithic design, which includes rotor blades, separation elements, and at least one release opening, the rotor no longer needs to be assembled from several parts, but can be manufactured as a single unit in a very simple way. Furthermore, it eliminates the need for any connections between the various components, such as by gluing, screwing, or welding. This reduces construction effort on the one hand, and improves operational safety on the other, as welding connections, which could lead to leaks during operation, are no longer required.

[0031] For example, a one-piece unit comprising blades, partition elements, and at least one release opening can be designed as a one-piece injection-molded part. Manufacturing using injection molding makes the rotor particularly cost-effective and economical to produce. Furthermore, the rotor needs to be designed to be demoldable, meaning it can be removed from the tooling after the injection molding process.

[0032] According to a preferred embodiment, a release opening is provided that connects the central inlet region of the rotor to the rear side of the rotor. This release opening is centrally located within the rotor.

[0033] In other embodiments of the pump unit according to the invention, a plurality of release openings are provided, the release openings being arranged around the central axis of the rotor, wherein each release opening connects the central inlet region of the rotor to the rear side of the rotor. For example, the release openings are arranged on a circle whose center is located on the central axis of the rotor. In these embodiments, a release opening may also be provided at the center of the rotor, surrounding the central axis. Other release openings are arranged around the central release opening.

[0034] Preferably, the rotor comprises an annular or disc-shaped active magnetic core and a sheath completely surrounding the active magnetic core, wherein the sheath is a component of a single unit including blades and separator elements. In this embodiment, the sheath, blades, separator elements, and all release openings are designed as a single integral component.

[0035] In a preferred embodiment, the separating element is designed and arranged such that the at least one release opening is partially visible from the inlet. This means that the separating element does not completely cover one or more release openings. This has the advantage that the release opening can be accessed from the pump inlet, thereby enabling, for example, processing of the release opening, such as subsequent descaling.

[0036] According to a preferred embodiment, the partition element includes a partition plate and an attachment web, wherein the partition plate has a maximum outer diameter in the radial direction, the maximum outer diameter being at most the same as the diameter of the central inlet region of the rotor, and wherein the attachment web is designed to secure the partition plate. Due to the design with the attachment web, it is no longer necessary (but still possible) to attach the partition element to the blade, thereby reducing the amount of construction work.

[0037] Preferably, the partition plate is designed such that its maximum outer diameter is smaller than the diameter of the central inlet region of the rotor. Thus, the partition plate's radial dimension is set such that it can be arranged between the blades without contacting them.

[0038] Another preferred embodiment is that each attachment web extends from the partition plate to the sheath, wherein radial openings for the recirculated flow are respectively disposed between adjacent attachment webs. In this manner, the partition plate is fixed to the sheath, wherein the recirculated flow can flow radially between the attachment webs. Preferably, the radial openings between the attachment webs are arranged such that, when viewed radially, they align with the gap between two adjacent blades, allowing the recirculated flow to flow unimpeded between the two adjacent blades.

[0039] In a preferred embodiment, each attachment web extends axially from the underside of the partition plate to the sheath. In this embodiment, the attachment web is preferably completely covered by the partition plate, so that the partition web is not visible from the entrance.

[0040] According to another preferred embodiment, each attachment web is disposed at the outer edge of the partition plate and extends radially from the outer edge. In this embodiment where the attachment web serves as a radial support, the attachment web is visible from the inlet. When viewed from the inlet of the pump housing, the partition element appears star-shaped.

[0041] In embodiments where the attachment webs are arranged at the outer edge of the partition plate, it is preferred that the attachment webs are arranged equidistantly on the outer edge of the partition plate.

[0042] A preferred variant of this embodiment is that each attachment web extends radially to one of the blades. Thus, each attachment web is in direct physical contact with one of the blades. This embodiment also has the advantage that the radial openings for recirculation flow arranged between the attachment webs are merged into the radial openings between adjacent blades, thereby particularly avoiding or at least significantly reducing turbulence.

[0043] Furthermore, especially for these embodiments, it is preferable that the number of attached webs equals the number of blades. In this way, a continuous channel is formed for the recirculating flow.

[0044] Furthermore, the present invention also proposes a centrifugal pump for conveying fluid, having a pump unit designed according to any one of the preceding claims, and the pump unit having a cylindrical cup for receiving a rotor, and a stator extending axially from a first axial end to a second axial end, wherein a cup-shaped recess is provided at the first axial end, and the cylindrical cup of the pump unit can be inserted into the cup-shaped recess, wherein the stator and the rotor together form an electromagnetic rotary actuator for rotating the rotor about the axial direction, wherein the stator is designed as a bearing and actuator stator, by means of which the rotor can be magnetically driven relative to the stator without contact and magnetically levitated without contact, wherein the rotor is passively magnetically stable relative to the axial direction and actively magnetically levitated in a radial plane perpendicular to the axial direction.

[0045] Particularly preferably, the electromagnetic rotary actuator is designed as a temple-type motor, wherein the stator has a plurality of coil cores, each comprising: a longitudinal leg extending from a first end along the axial direction to a second end; and a transverse leg disposed at the second end of the longitudinal leg and in the radial plane, and extending radially from the longitudinal leg, wherein the coil cores are arranged around the rotor relative to the circumferential direction such that the rotor is arranged between the transverse legs of the coil cores, and wherein at least one concentrated winding is provided at each longitudinal leg, the winding surrounding the corresponding longitudinal leg.

[0046] Other advantageous measures and embodiments of the invention will be apparent from the dependent claims. Attached Figure Description

[0047] The invention will be explained in more detail below with reference to embodiments and the accompanying drawings. The schematic diagrams (partially in cross-sectional view) show:

[0048] Figure 1 A perspective view of a centrifugal pump according to the prior art, shown in partial cross-section.

[0049] Figure 2 A pump unit according to the prior art, shown in cross-sectional view.

[0050] Figure 3 An embodiment of the pump unit according to the invention, shown in cross-sectional view.

[0051] Figure 4 Partially shown in cross-section from Figure 3 A perspective view of the rotor of the pump unit.

[0052] Figure 5 : along Figure 4 The section line VV in the figure shows a cross-sectional view of the rotor.

[0053] Figure 6 The first variant of the rotor shown in cross-section.

[0054] Figure 7 Partially shown in cross-section from Figure 6 A perspective view of the first variant of the rotor.

[0055] Figure 8 : along Figure 7 Sections VIII-VIII in the diagram show a cross-sectional view of the first variant of the rotor.

[0056] Figure 9 The second variant of the rotor shown in cross-section.

[0057] Figure 9A The second variant of the rotor is shown in a plan view as seen from the inlet of the pump casing.

[0058] Figure 10 Partially shown in cross-section from Figure 9 A perspective view of the second variant of the rotor.

[0059] Figure 11 : along Figure 10 The section along section line XI-XI shows a cross-sectional view of the second variant of the rotor.

[0060] Figure 12The third variant of the rotor is shown in a plan view as seen from the inlet of the pump casing.

[0061] Figure 13 Partially shown in cross-section from Figure 12 A perspective view of the third variant of the rotor.

[0062] Figure 14 : along Figure 13 The section line XIV-XIV in the figure shows a cross-sectional view of the third variant of the rotor, and

[0063] Figure 15 : A schematic cross-sectional view of an embodiment of the centrifugal pump according to the present invention. Detailed Implementation

[0064] As explained above, Figure 1 A centrifugal pump 200' known from the prior art is shown, which has a rotor 10' with non-contact magnetic support and non-contact magnetic drive. Figure 2 A cross-sectional view shows a pump unit 1' known from the prior art, and this pump unit is adapted, for example, from... Figure 1 Centrifugal pump 200'.

[0065] Figure 3 With Figure 2 The corresponding sectional view shows an embodiment of the pump unit according to the invention, the pump unit being generally indicated by reference numeral 1.

[0066] Pump unit 1 is designed as a centrifugal pump 200 for conveying fluids (see...) Figure 15 The pump unit 1 comprises a pump housing 2 having an inlet 21 and an outlet 22 for fluid. A rotor 10 for conveying fluid is arranged in the pump housing 2, which forms the centrifugal wheel or impeller of the pump unit 1, and thus the centrifugal wheel or impeller of the centrifugal pump 200. The rotor 10 is rotatable about a desired axis of rotation, which defines an axial direction A. This desired axis of rotation is the central axis M of the rotor 10.

[0067] Relative to the axial direction A, the rotor 10 extends from the front side facing the inlet to the rear side away from the inlet 21.

[0068] To better understand, Figure 4 The rotor 10 of pump unit 1 is shown in perspective, with one sector of rotor 10 cut off. Furthermore, Figure 5 The rotor 10 is shown in cross-section. The section is along... Figure 4 The cross-sectional line VV is formed in the middle.

[0069] The direction perpendicular to the axial direction A is called the radial direction. In the following text, the term "axial" is used in its commonly accepted meaning, i.e., "along the axial direction" or "relative to the axial direction." The term "radial" is used in its commonly accepted meaning, i.e., "along the radial direction" or "relative to the radial direction."

[0070] Pump unit 1 is designed for non-contact magnetic levitation of rotor 10 and non-contact magnetic drive of rotor 10. This can be particularly compatible with systems based on... Figure 1 and Figure 2 This is achieved in a similar manner as explained. Therefore, the pump unit 1 according to the invention can be compared with [other systems] in terms of magnetic levitation and magnetic drive. Figure 1 or Figure 2 The pump unit 1' in the pump unit 1 is designed in a similar manner. For this purpose, the rotor 10 of the pump unit 1 includes a magnetically active core 101, which is designed, for example, as a permanent magnet ring or permanent magnet disk, and is surrounded by a sheath 102. The sheath 102 is preferably designed as a plastic sheath. For example, the sheath 102 is made of PTFE or PFA. The magnetically active core 101 is encapsulated in the sheath 102, that is, the sheath 102 completely and preferably sealingly surrounds the magnetically active core 101. As a result, the magnetically active core 101 is protected from the influence of fluids. For example, the sheath 102 can be manufactured by spraying plastic around the magnetically active core 101.

[0071] The effective magnetic core 101 of the rotor 10 is a component of the rotor 10 that magnetically cooperates with the stator 100 to generate torque and magnetic levitation force.

[0072] Furthermore, the rotor 10 includes a plurality of blades 103 for conveying fluid from inlet 21 to outlet 22. The blades 103 are arranged on the sheath 102 of the active magnetic core 101. The blades 103 are preferably made of plastic and are preferably designed as a single piece with the sheath 102. Alternatively, the individual blades 103 or the entire blades 103 can be manufactured in a separate manufacturing process and then attached to the sheath 102 of the active magnetic core 101, for example, by means of a welding process.

[0073] The impeller with blades 103 formed by the rotor 10 is preferably designed as a radial impeller, which is approached by fluid from the inlet 21 in the axial direction A and then redirected in the radial direction.

[0074] Pump housing 2 includes a cover portion 4 and a bottom portion 3, which are sealed together. This is not essential for understanding the invention. Figure 3 The details are not presented in greater detail. The bottom portion 3 includes a cylindrical cup 31 for receiving the rotor 10. The cup 31 is preferably designed and arranged such that it can be inserted into a cup-shaped recess in the stator 100, as shown below. Figure 15 It is presented schematically in the text.

[0075] Stator 100 ( Figure 15 ) Extends along the axial direction A from the first axial end 110 to the second axial end 120, and has a stator housing ( Figure 15 (Not shown in the image), the stator housing is designed in a substantially cylindrical manner. A cup-shaped recess is arranged at the first axial end 110 of the stator 100, preferably centered in the end face forming the first axial end 110 of the stator 100. The design of the stator housing with the cup-shaped recess is particularly capable of being similar to that based on Figure 1 This is achieved in the manner explained for the stator housing 130' and the cup-shaped recess 121'. Therefore, the cup 31 is arranged and designed in such a way that it can be inserted into the recess 121' in the first axial end 110' of the stator 100'. Figure 1 In the coil core 125', the effective magnetic core 101 is arranged between the transverse legs 127' of the coil core 125'.

[0076] As in Figure 3 As can be seen in the figure, a pump chamber 23 exists above the cup 31, which is defined by the pump housing 2, and the blades 103 of the rotor 10 are arranged in this pump chamber. The pump chamber 23 is designed at least substantially cylindrically, wherein the diameter of the pump chamber 23 is larger than the inner diameter of the cup 31. As a result, the pump housing 2 has a flange-like protrusion 24, which, according to the figure, defines the pump chamber 23 downward relative to the axial direction A.

[0077] The inlet 21 is centrally located in the cover portion 4 of the pump housing 2, allowing fluid to flow axially towards the rotor 10.

[0078] Each blade 103 extends from a radially inwardly arranged leading edge 109 to a radially outwardly arranged trailing edge 110. In the embodiment described herein, the blades 103 are designed, by way of example, such that they extend in a straight line in the radial direction from the leading edge 109 to the trailing edge 110 and have a constant height over their entire extension. Here, height refers to the extension of the blade 103 in the axial direction A. As mentioned, this design is to be understood as an example only. In other embodiments, the blades 103 are designed, for example, to be curved relative to the radial direction, and / or have a height that varies from the leading edge 109 to the trailing edge 110 in the axial direction A. For example, Figure 15 An embodiment is shown in which the blade 103 has a greater height at its leading edge 109 compared to its trailing edge 110.

[0079] In addition, an annular cover plate 8 is provided, which is arranged on the upper edge of the blade 103 facing the inlet 21. The cover plate 8 covers all blades 103. Relative to the radial direction, the annular cover plate 8 extends from the leading edge 109 of the blade 103 to its trailing edge 110. The cover plate 8 can be designed as a single piece with the blade 103.

[0080] As in Figure 4 and Figure 5 As can be clearly identified, the blades 103 of the rotor 10 are arranged around a central inlet region 25 where there are no blades 103. The leading edges 109 of the blades 103 lie on a line, here a circular line, which has a distance other than zero from the central axis M of the rotor 10. The diameter D1 of the central inlet region 25 is determined by the distance between the leading edge 109 of the blades 103 and the central axis M of the rotor 10. This diameter D1 of the central inlet region 25 is equal to twice the distance between the leading edge 109 of the blades 103 and the central axis M of the rotor 10. In the embodiment described herein, the diameter D1 of the central inlet region 25 is the same as the inner diameter of the annular cover plate 8.

[0081] For example, if the leading edge 109 of the blade does not extend parallel to the axial direction A, but is inclined relative to the axial direction A, then the diameter D1 of the central inlet region 25 is determined by the distance of the leading edge 109 of the blade 103 at the upper edge facing the inlet 21.

[0082] The rotor 10 also includes at least one release opening 104 for generating a recirculation flow RF, which is guided from the rear side of the rotor 10 away from the inlet 21 along the direction of the central inlet region 25. Figures 3 to 5 In the embodiment presented, a single release opening 104 is provided, which is cylindrical and extends along the axial direction A. The release opening 104 is centrally located within the rotor 10 such that its axis coincides with the central axis M of the rotor 10. The release opening 104 extends from the central inlet region 25 through the rotor 10 along the axial direction A to the rear side of the rotor 10. The rotor 10 also includes a separating element 7 disposed in the central inlet region 25 of the rotor 10, which redirects the recirculation flow RF, which flows from the rear side of the rotor 10 through the release opening 104, from the axial direction A to the radial direction.

[0083] Preferably, the partition element 7 includes a partition plate 71 aligned perpendicular to the axial direction A, and a plurality of attachment webs 72 for securing the partition plate 71. The partition plate 71 is here designed in the form of a disk and has an outer diameter D2. In other embodiments, the partition plate 71 may also have a shape different from a disk and / or may have flow guiding elements. In this case, the outer diameter D2 refers to the maximum outer diameter D2, i.e., the maximum extension of the partition plate 71 in the radial direction.

[0084] The partition plate 71 is arranged in the central inlet region 25, centered radially, meaning the center point of the partition plate 71 is located on the central axis M of the rotor 10. Relative to the axial direction A, the partition plate 71 is arranged such that, according to the figure (… Figure 3 , Figure 4For each blade 103, the upper portion of the leading edge 109 is arranged above the partition plate 71 relative to the axial direction A, and the lower portion of the leading edge 109 is arranged below the partition plate 71 relative to the axial direction A.

[0085] The entire area of ​​the blades 103 arranged above the partition plate 71 relative to the axial direction A forms a first centrifugal wheel 105, which is mainly used to generate the mainstream HF, which flows from the inlet 21 to the outlet 22 along the axial direction A. The mainstream HF is indicated by the arrow HF, which is shown in solid line.

[0086] A second centrifugal wheel 106 is formed over the entire area of ​​the blades 103 arranged below the partition plate 71 relative to the axial direction A. This second centrifugal wheel is primarily used to generate a recirculation flow RF, which is guided from the rear side of the rotor 10 away from the inlet 21 through the release opening 104 along the direction of the central inlet region 25. The recirculation flow RF is indicated by the arrow RF, represented by a dashed line.

[0087] Separating element 7 redirects the recirculating flow RF from the axial direction A to the radial direction. Separating element 7 prevents the mainstream HF and the recirculating flow RF from directly colliding or contacting in the region of the end of the release opening 104 facing the central inlet region 25. Therefore, due to separating element 7, the recirculating flow RF and the mainstream HF are prevented from meeting head-on, i.e., becoming flows guided relative to each other. Thus, due to separating element 7, the recirculating flow RF is at least partially separated from the mainstream HF in the region of the central inlet region 25. The recirculating flow RF is first redirected radially by separating element 7. No substantial mixing of the mainstream HF and the recirculating flow RF occurs until the recirculating flow RF passes the outer edge of separating plate 71. The outer edge of separating plate 71 refers to its radial outer edge. Because the recirculating flow RF has been redirected radially, it can mix with the mainstream HF with almost no strong turbulence.

[0088] As in Figure 3 As can be optimally identified, the outer diameter D2 of the partition plate 71 is smaller than the diameter D1 of the central inlet region 25. In this embodiment, the partition plate 71 is entirely located within the central inlet region 25 and has no physical contact with the blade 103. The leading edge 109 of the blade 103 is arranged around the partition plate 71 without contacting it. This embodiment has the advantage that the partition plate 71 can be manufactured in a simple manner, for example, during the manufacture of the rotor 10.

[0089] The outer diameter D2 of the partition plate 71 is larger than the inner diameter of the release opening 104, so that the release opening 104 is completely covered by the partition plate 71. Therefore, the release opening 104 is not visible from the inlet 21.

[0090] However, it is also possible to have an embodiment in which the release opening 104 is visible from the inlet 21 portion, i.e., the partition plate 71 does not completely cover the release opening 104. For example, this can be achieved in such a way that the outer diameter D2 of the partition plate 71 is smaller than the inner diameter of the release opening 104.

[0091] The separator element 7 includes attachment webs 72 for securing the separator plate 71. All attachment webs 72 are arranged on the underside of the separator plate 71. Here, the underside of the separator plate 71 refers to the boundary surface of the separator plate 71 facing the release opening 104. Each attachment web 72 extends from the underside of the separator plate 71 along the axial direction A to the sheath 102, and the attachment web 72 is supported on the sheath 102. Thus, the separator plate 71 is secured to the sheath 102 by means of the attachment webs 72. Therefore, it is no longer necessary to attach the separator plate 71 or separator element 7 to the blade 103.

[0092] As in Figure 5 As can be best identified, the attachment web 72 is arranged on a circle relative to the radial direction, which is concentric with the release opening 104 and has a larger diameter than the release opening 104. The diameter of the circle on which the attachment web is arranged is smaller than the outer diameter D2 of the partition plate 71. Therefore, the attachment web 72 is arranged on the underside of the partition plate 71 in such a way that they are not visible from the inlet 21 of the pump housing 2.

[0093] The attachment webs 72 are preferably arranged equidistantly around the release opening 104. A total of five attachment webs 72 are provided. Between two adjacent attachment webs, a radial opening 73 is provided, through which the recirculated flow RF flows radially out of the release opening 104 toward the outlet 22.

[0094] Preferably, the attachment web 72 is arranged such that the radial opening 73 is aligned in the radial direction with the gap 74 between the leading edges 109 of two adjacent blades 103. This allows for... Figure 5 The recirculated flow RF exiting the radial opening 73 can flow unimpeded into the gap 74 between adjacent blades 103. In this way, the formation of eddies in the recirculated flow RF is at least significantly reduced. For this embodiment, it is particularly advantageous if the number of attachment webs 72 is equal to the number of blades. In the embodiment described herein, as an example, the rotor 10 has exactly five blades. Therefore, the separator element 7 has exactly five attachment webs 72, each located on the line connecting the central axis M of the rotor 10 and one of the leading edges 109 of the blades 103. Thus, each of these five radial openings 73 is aligned radially with exactly one of the gaps 74 between adjacent blades 103.

[0095] According to the present invention, the plurality of blades 103, the separating element 7, and the release opening 104 are designed as a single-piece unit. Particularly preferably, the sheath 102 is also a component of this single-piece unit. Furthermore, preferably, the cover plate 8 arranged on the blades 103 is also a component of this single-piece unit. Particularly preferably, except for the active magnetic core 101, the rotor 10 is designed as a single-piece unit as a whole. Therefore, in this embodiment, it is no longer necessary to connect the various components of the rotor 10 to each other by means of joining methods such as gluing, welding, screwing, or similar methods. This single-piece unit has an integral design, that is, it is not composed of several parts, but is a single piece. Therefore, this single-piece unit has no adhesion, threaded connections, welds, seals, or contacts between adjacent components.

[0096] Because of the unit’s monolithic design, which includes at least blades 103, separating elements 7 and at least one release opening 104 and preferably all components except the demagnetized effective magnetic core 101 of rotor 10, rotor 10 no longer needs to be assembled from several parts, but can be designed as an integral device.

[0097] Since it is not necessary to connect the components by means of gluing, screwing or welding, and since there is no need for sealing between the components of the rotor 10, this results in very high operational reliability.

[0098] For example, the single-piece unit is designed as a single-piece injection-molded part, meaning it can be manufactured using an injection molding process. This injection molding process is preferably designed so that the active magnetic core 101 is integrated into the injection molding process. For example, the sheath 102 can be manufactured by spraying plastic onto the active magnetic core 101 during the injection molding process.

[0099] Preferably, the rotor 10 is manufactured by combining an injection molding process with subsequent subtractive machining methods (e.g., chip removal methods, such as milling or drilling).

[0100] Of course, other methods are also applicable to manufacturing the rotor 10, such as additive manufacturing methods, such as methods called 3D printing.

[0101] Preferably, the one-piece unit is made of plastic. For example, the one-piece unit may be injection molded from one of the following plastics:

[0102] Polyvinyl chloride (PVC), perfluoroalkoxy polymer (PFA), polypropylene (PP), polyethylene (PE).

[0103] The rotor 10 can also be manufactured using a sintering process and subsequent subtractive machining methods. The sheath 102, for example made of powder or granules, is then pressed onto the active magnetic core 101 using pressure and optional heat treatment, so that the active magnetic core 101 is completely surrounded. Plastic is molded around the active magnetic core 101 by applying heat and / or pressure to form a monolithic block, such as a cylinder. The rotor 10, having blades 103, separator elements 7, at least one release opening 104, and optional cover plate 8, is then shaped to the desired form by means of a chip removal process.

[0104] In addition to, or instead of, powder or granules, several plastic parts can be joined together into a single block using heat and / or pressure, into which the magnet has been pre-inserted, and which completely surrounds the magnet after the joining process. Then, by means of a descaling process, the rotor 10, having blades 103, a separating element 7, at least one release opening 104, and an optional cover plate 8, is shaped to the desired form.

[0105] exist Figures 6 to 8 The first variant of rotor 10 is presented in the image. Figure 6 The rotor is shown in cross-section, with the section formed along the axial direction A. Figure 7 A perspective view, partially shown in cross-section, is shown, which is consistent with... Figure 4 The view in the text corresponds to this. Figure 8 It shows along Figure 7 A cross-sectional view of the first variant of rotor 10 with section lines VIII-VIII in the diagram. Figure 8 The view in Figure 5 The view in the text corresponds to this.

[0106] In a first variant of rotor 10, several release openings 104, 104a are provided. One of the release openings 104 is also centrally located within rotor 10, such that the axis of this release opening 104 coincides with the central axis M of rotor 10. Multiple additional release openings 104a are arranged around this centrally located release opening 104. As an example, ten additional release openings 104a are provided, arranged on a circle whose center point is on the central axis of rotor 10. Each release opening 104, 104a is designed as a cylindrical hole or opening extending axially from the central inlet region 25 through rotor 10 to its rear side. All release openings 104, 104a are arranged parallel to each other. The circle on which the additional release openings 104a are arranged has a diameter smaller than the outer diameter D2 of partition plate 71, such that all release openings 104, 104a are completely covered by partition plate 71. Therefore, no release openings 104, 104a are visible from inlet 21.

[0107] However, it is also possible to implement an embodiment in which one or more of the release openings 104, 104a are partially or fully visible from the inlet 21, i.e., the partition plate 71 does not completely cover all the release openings 104, 104a. For example, this can be achieved such that the outer diameter D2 of the partition plate 71 is the same as or smaller than the diameter of the circle in which the additional release openings 104a are arranged.

[0108] exist Figure 9 , Figure 9A , Figure 10 and Figure 11 The second variant of rotor 10 is presented in the image. Figure 9 The rotor 10 is shown in cross-section, with the section formed along the axial direction A. Figure 9A The rotor 10 is shown in a plan view as seen from the inlet 21 of the pump housing 2. Figure 10 It shows the relationship with Figure 4 The corresponding parts in the illustration are shown in perspective view in cross-section. Figure 11 It shows along Figure 10 A cross-sectional view of the second variant of rotor 10 with section line XI-XI in the figure. Figure 11 The view in Figure 5 Corresponding to the view in the diagram. In the second variant of rotor 10, only one release opening 104 is also provided, which is centrally located. It should be understood that the following embodiment of the second variant of rotor 10 is also possible, wherein several release openings 104, 104a are provided, for example, according to the first variant of rotor 10 (see...). Figure 8 It is similar to the way described.

[0109] In a second variant of the rotor 10, the attachment web 71 of the partition element 7 (which is used to fix the partition 71) is arranged at the outer edge of the partition 71. Each attachment web 72 extends radially outward from the outer edge of the partition 7. Additionally, each attachment web 71 extends axially A to the sheath 102, on which the attachment web 71 is supported. In this embodiment where the attachment webs 72 are arranged at the outer edge of the partition 71, it is also preferable that the number of attachment webs 72 (here, for example, five) is the same as the number of blades 103 of the rotor 10. When viewed from the inlet, the partition element 7 having the partition 71 and the attachment webs 72 arranged at its edges has a star-shaped appearance.

[0110] The attachment webs 72 are preferably arranged at equal intervals at the outer edge of the partition plate 71. Between two adjacent attachment webs 72, one of the radial openings 73 is arranged, through which the recirculated flow RF can flow radially from the release opening 104 to the outlet 22.

[0111] Preferably, in a second variant of the rotor 10, the attachment web 72 is also arranged such that the radial opening 73 is aligned in the radial direction with the gap 74 between the leading edges 109 of two adjacent blades 103. This allows for... Figure 11 The recirculated flow RF exiting the radial opening 73 can then flow unimpeded into the gap 74 between adjacent blades 103. In this way, the formation of vortices in the recirculated flow RF is at least significantly reduced.

[0112] In a second variant of the rotor 10, the partition plate 71 of the partition element 10 is again designed in the shape of a disk. (As in...) Figure 9 As can be identified, in the second variant of rotor 10, the outer diameter D2 of partition plate 71 is smaller than the inner diameter of the centrally located release opening 104. As a result, the release opening 104 is partially visible from inlet 21 because partition plate 71 does not completely cover the release opening 104. An annular gap 104b exists around partition plate 71, which is not covered by partition plate 71 and can be seen from inlet 21 of pump housing 2. This embodiment has the advantage that during the manufacture of rotor 10, milling tools can be inserted into the annular gap 104b in the axial direction A, thereby making it easier or more precise to machine partition plate 71, particularly in the area between two adjacent attachment webs 72.

[0113] Furthermore, preferably, the attachment web 72 terminates at a distance D3 relative to the radial direction in front of the leading edge 109 of the blade 103, wherein D3 is large enough that a milling tool can be fitted between the attachment web 72 and the leading edge 109 of the blade 103. Therefore, D3 is the distance between the radially outer end of the attachment web 72 and the leading edge 109 of the blade 103, measured in the radial direction. Figure 11 In the embodiment presented, distance D3 is equal to the distance between the radially outer end of the attachment web 72, measured radially, and the radially inner edge of the cover plate 8. From a practical standpoint, it is preferable that distance D3 is at least one-thirtieth of the distance between the upper side of the sheath 102 arranging the blades 103, measured axially in direction A, and the upper side of the rotor 10 facing the inlet 21 at the inlet region 25, preferably at least one-fifteenth of that distance, where the inlet region is formed by the cover plate 8. Of course, in a second variant, the rotor may also be implemented in a manner where the release opening 104 is completely covered by the partition plate 71, making it invisible from the inlet 21. For this purpose, for example, the outer diameter D2 of the partition plate 71 is larger than the inner diameter of the release opening 104.

[0114] Figures 12 to 14 The third variant of rotor 10 is presented in the paper. Figure 12 The rotor 10 is shown in a plan view as seen from the inlet of the pump housing 2. Figure 13A perspective view, partially shown in cross-section, is shown, which is consistent with... Figure 4 The diagram in the image corresponds to this. Figure 14 It shows along Figure 13 A cross-sectional view of the third variant of rotor 10 with section lines XIV-XIV in the figure. Figure 14 The illustrations and Figure 5 The diagram in the image corresponds to this.

[0115] A third variant of the rotor 10 is designed in a similar manner to the second variant, and specifically features an attachment web 72 disposed at the outer edge of the partition plate 71. However, the attachment web 72 extends radially to the blade 103. Thus, each attachment web 72 extends radially to the leading edge 109 of one of the blades 103. Preferably, each attachment web 72 is incorporated into one of the blades 103. Preferably, a circularly designed transition region 721 is provided at the radially outer end of each attachment web 72, in which the attachment web 72 is incorporated into the leading edge 109 of the blade 103.

[0116] Furthermore, the present invention proposes a centrifugal pump 200 for conveying fluid using pump unit 1, wherein pump unit 1 is designed according to the present invention. Figure 15 An embodiment of a centrifugal pump 200 according to the present invention is shown in a schematic cross-sectional view. The centrifugal pump 200 includes a stator 100 extending along an axial direction A from a first axial end 110 to a second axial end 120, wherein a cup-shaped recess is provided at the first axial end 110. Figure 15 (Not shown in the image), the cylindrical cup 31 of the pump unit 1 can be inserted into the cup-shaped recess. The stator 100 together with the rotor 10 forms an electromagnetic rotary actuator for rotating the rotor 10 about the axial direction A, wherein the stator 100 is designed as a bearing and actuator stator, by means of which the rotor 10 can be magnetically driven relative to the stator 100 in a non-contact manner and can be magnetically levitated in a non-contact manner, wherein the rotor 10 is passively magnetically stable relative to the axial direction A and actively magnetically levitated in a radial plane E perpendicular to the axial direction A.

[0117] Stator 100 includes a stator housing, which, for better overview, is not shown in the image. Figure 15 Presented in the middle. However, for example, stator 100 is able to be with Figure 1 The stator 100' presented in the image is designed in a similar manner to the stator housing 130', in which a recess 121' is provided, into which the cylindrical cup 31 of the bottom portion 3 of the pump housing 1 is inserted.

[0118] Particularly preferably, the electromagnetic rotary drive having a rotor 10 and a stator 100 is designed as a temple-type motor, wherein the stator 100 has a plurality of coil cores 125, each comprising: a longitudinal leg 126 extending from a first end in an axial direction A to a second end; and a transverse leg 127 disposed at the second end of the longitudinal leg 126 and in a radial plane E. The transverse leg 127 extends radially inward from the longitudinal leg 126 toward the rotor 10.

[0119] All the first ends of the longitudinal legs 126 (i.e., the lower ends as shown in the figure) are connected to each other via the back iron 122 for conducting magnetic flux.

[0120] The coil core 125 is arranged around the rotor 10 in the circumferential direction, such that the rotor 10 is arranged between the transverse legs 127 of the coil core 125. At least one concentrated winding 160 is provided at each longitudinal leg 126, the winding surrounding the corresponding longitudinal leg 126.

[0121] The concentrated windings 160 generate the electromagnetic fields required for the magnetic drive and levitation of the rotor 10. Therefore, these concentrated windings 160 can generate these electromagnetic fields in operation, producing torque on the rotor 10 in a known manner, and allowing an arbitrary adjustable lateral force to be applied to the rotor 10 in the radial direction, enabling active control or adjustment of the rotor 10's radial position, i.e., its position in the radial plane E perpendicular to the axial direction A. Regarding the other three degrees of freedom—its position in the axial direction A and its tilt relative to the radial plane E perpendicular to the desired axis of rotation (two degrees of freedom)—the rotor 10 is passively magnetically levitated or stabilized by magnetic reluctance, meaning it cannot be controlled.

Claims

1. A pump unit for a centrifugal pump, the centrifugal pump comprising the pump unit and a stator (100) extending along an axial direction (A) from a first axial end (110) to a second axial end (120), wherein, A cup-shaped recess is provided at the first axial end (110), into which the pump unit (1) can be inserted. The pump unit (1) has: a pump housing (2) having an inlet (21) and an outlet (22) for the fluid to be conveyed; and a rotor (10) arranged in the pump housing (2), the rotor having a plurality of blades (103) for conveying the fluid, wherein the rotor (10) is rotatable about the axial direction (A), wherein the pump unit (1) is designed for non-contact magnetic levitation of the rotor (10) by means of the stator (100) and non-contact magnetic drive of the rotor (10), wherein the blades (103) of the rotor (10) surround the center of the rotor (10). A central inlet region (25) is arranged, wherein the rotor (10) includes at least one release opening (104, 104a) for generating a recirculation flow (RF) that is guided from the rear side of the rotor (10) away from the inlet (21) along the direction of the central inlet region (25) of the rotor (10), and wherein the rotor (10) also has a partition element (7) arranged in the central inlet region (25) that redirects the recirculation flow (RF) in a radial direction perpendicular to the axial direction (A), characterized in that the plurality of blades (103) of the rotor (10), the partition element (7) and the at least one release opening (104, 104a) are designed as a single unit.

2. The pump unit according to claim 1, wherein, A release opening (104) is provided, which connects the central inlet region (25) of the rotor to the rear side of the rotor (10).

3. The pump unit according to claim 1, wherein, Multiple release openings (104, 104a) are provided, the release openings are arranged around the central axis (M) of the rotor, and each release opening (104, 104a) connects the central inlet region (25) of the rotor to the rear side of the rotor (10).

4. The pump unit according to any one of the preceding claims, wherein, The rotor (10) includes an annular or disc-shaped active magnetic core (101) and a sheath (102) that completely surrounds the active magnetic core (101), wherein the sheath (102) is a component of the single-piece unit including the blade (103) and the separating element (7).

5. The pump unit according to any one of the preceding claims, wherein, The separating element (7) is designed and arranged such that at least one release opening (104, 104a) is partially visible from the inlet.

6. The pump unit according to any one of the preceding claims, wherein, The separating element (7) includes a separating plate (71) and an attachment web (72), wherein the separating plate (71) has a maximum outer diameter (D2) in the radial direction, the maximum outer diameter (D2) being at most the same as the diameter (D1) of the central inlet region (25) of the rotor (10), and wherein the attachment web (72) is designed to fix the separating plate (71).

7. The pump unit according to claim 6, wherein, The maximum outer diameter (D2) of the partition plate (71) is smaller than the diameter (D1) of the central inlet region (25) of the rotor (10).

8. The pump unit according to any one of claims 4 and 6 to 7, wherein, Each attachment web (72) extends from the partition plate (7) to the sheath (102), and wherein radial openings (73) for the recirculation flow (RF) are respectively provided between adjacent attachment webs (72).

9. The pump unit according to claim 8, wherein, Each attachment web (72) extends from the underside of the partition plate (71) along the axial direction (A) to the sheath (102).

10. The pump unit according to claim 8, wherein, Each attachment web (72) is arranged at the outer edge of the partition plate (7) and extends from the outer edge in the radial direction.

11. The pump unit according to claim 10, wherein, The attached web (72) is arranged at equal intervals on the outer edge of the partition plate (71).

12. The pump unit according to any one of claims 10 to 11, wherein, Each attachment web (72) extends along the radial direction to one of the blades (103).

13. The pump unit according to any one of claims 10 to 12, wherein, The number of attached webs (72) is equal to the number of blades (103).

14. A centrifugal pump for conveying fluid, comprising a pump unit designed according to any one of the preceding claims, wherein the pump unit has a cylindrical cup (31) for receiving a rotor (10) and a stator (100) extending in an axial direction (A) from a first axial end (110) to a second axial end (120), wherein, A cup-shaped recess is provided at the first axial end (110), into which the cylindrical cup (31) of the pump unit (1) can be inserted. The stator (100) together with the rotor (10) forms an electromagnetic rotary actuator for rotating the rotor (10) about the axial direction (A). The stator (100) is designed as a bearing and actuator stator, by means of which the rotor (10) can be magnetically driven and magnetically levitated relative to the stator (100) without contact. The rotor (10) is passively magnetically stable relative to the axial direction (A) and actively magnetically levitated in a radial plane (E) perpendicular to the axial direction (A).

15. The centrifugal pump according to claim 14, wherein, The electromagnetic rotary actuator is designed as a temple motor, wherein the stator (100) has a plurality of coil cores (125), each comprising: a longitudinal leg (126) extending from a first end along the axial direction (A) to a second end; and a transverse leg (127) disposed at the second end of the longitudinal leg (126) and in the radial plane (E), and extending radially from the longitudinal leg (126), wherein the coil cores (125) are arranged around the rotor (10) relative to the circumferential direction such that the rotor (10) is arranged between the transverse legs (127) of the coil cores (125), and wherein at least one concentrated winding (160) is provided at each longitudinal leg (125), the winding surrounding the corresponding longitudinal leg (126).

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