Pump unit for centrifugal pump and centrifugal pump

Abstract

The invention relates to a pump unit for a centrifugal pump for conveying a fluid, comprising a pump housing having an inlet and an outlet for the fluid and a rotor arranged in the pump housing for conveying the fluid, which rotor can be rotated about an axial direction, the pump unit being designed for contactless magnetic levitation and contactless magnetic drive of the rotor, wherein the pump housing has a bottom part and a cover for closing the bottom part, and wherein the bottom part has a cylindrical cup for receiving the rotor and a substantially annular first sealing surface for sealing interaction with the cover, and wherein the cover has a substantially annular second sealing surface designed for sealing interaction with the first sealing surface. One of the two sealing surfaces is designed as a ribbed surface having at least one radial sealing rib which extends in the circumferential direction along the entire sealing surface, and the other is designed as a smooth surface. The invention further relates to a centrifugal pump for conveying a fluid, comprising such a pump unit.

Description

Technical Field

[0001] The invention relates to a pump unit of a centrifugal pump for conveying fluids according to the preamble of the independent patent claim. The invention further relates to a centrifugal pump having such a pump unit. Background Art

[0002] Centrifugal pumps are known which comprise a pump unit and a drive unit, wherein a rotor is arranged in the pump unit, which rotor forms the impeller of the centrifugal pump. The stator is arranged in the drive unit. In the pump unit, the rotor can be magnetically supported contactlessly by means of the drive unit and can be driven contactlessly to rotate about an axial direction. Such centrifugal pumps are known, for example, by the applicant under the product name The pump is available on the market.

[0003] The stator and rotor form an electromagnetic rotary drive. For example, in In the case of pumps, the electromagnetic rotary drive is designed according to the principle of a bearingless motor. The term bearingless motor refers to an electromagnetic rotary drive in which the rotor can be fully magnetically supported relative to the stator, wherein no separate magnetic bearing is provided. For this purpose, the stator is designed as a bearing and drive stator, which is both the stator of the electric drive and the stator of the magnetic bearing. The electrical windings of the stator can be used to generate a magnetic rotating field, which on the one hand exerts a torque on the rotor, which enables the rotor to rotate around the desired rotation axis defined by the axial direction, and on the other hand exerts a lateral force that can be adjusted arbitrarily on the rotor, so that the radial position of the rotor can be actively controlled or adjusted. Thus, three degrees of freedom of the rotor can be actively adjusted, namely its rotation and its radial position (two degrees of freedom). With regard to the other three degrees of freedom, namely its position in the axial direction and its tilt relative to a radial plane perpendicular to the desired rotation axis (two degrees of freedom), the rotor is passively magnetically supported or stabilized by magnetic resistance, i.e. it cannot be controlled. The complete magnetic bearing of the rotor and the lack of a separate magnetic bearing are properties that give the bearingless motor its name. In bearings and drive stators, the bearing function cannot be separated from the drive function.

[0004] Of course, other designs of centrifugal pumps are also known in which the rotor is magnetically supported without contact, for example those in which a separate magnetic bearing is provided for the rotor so that the magnetic bearing function is separated from the drive function. For example, separate coils are provided for this purpose, with which only the bearing forces for the rotor are realized, but these coils do not contribute to the drive of the rotor.

[0005] Centrifugal pumps with rotors that are contactless magnetically supported and contactless magnetically driven, such as those designed according to the principle of bearingless motors, have proven themselves in a large number of applications. Due to the lack of mechanical bearings, such centrifugal pumps are particularly suitable for applications in which very sensitive substances are conveyed, such as blood pumps, or for applications with very high demands on purity, such as in the semiconductor industry, the pharmaceutical industry, the biotechnology industry, or for applications in which abrasive or aggressive substances are conveyed that would very quickly destroy mechanical bearings, such as pumps for slurries, sulfuric acid, phosphoric acid or other chemicals in the semiconductor industry.

[0006] Figure 1 A representation of a centrifugal pump known from the state of the art designed according to the principle of a bearingless motor is shown. For example, this is Pump. For a better understanding, Figure 1 Segments have been cut away so that the interior of the centrifugal pump is visible.

[0007] For instructions Figure 1 and Figure 2 The representations in 2 are devices from the state of the art, whereby the reference numerals are each marked with an inverted comma or a dash. The centrifugal pump is designated as a whole by the reference numeral 200 ′.

[0008] The centrifugal pump 200' comprises a drive unit 100' and a pump unit 1'. For better understanding, the pump unit 1' is Figure 2 , where the cross section is in the axial direction A.

[0009] A rotor 10' is arranged in the pump unit 1', the rotor 10' forming a wheel or impeller with which a fluid is conveyed. The drive unit 100' comprises a motor housing 120', in which a stator 102' is arranged, the stator 102' together with the rotor 10' forming an electromagnetic rotary drive for rotating the rotor about an axial direction A. According to the principle of a bearingless motor, the drive unit 100' is designed as a contactless magnetic bearing for the rotor 10'. For this purpose, the stator 102' is designed as a bearing and a drive stator, by means of which the rotor 10' can be magnetically driven contactlessly for rotation about an axial direction A and can be magnetically supported contactlessly relative to the stator 102', wherein the rotor 10' is passively magnetically stabilized relative to the axial direction A and is actively magnetically supported in a radial plane perpendicular to the axial direction A, the plane being defined by Figure 1 The motor housing 120 ′ has in one of its axial end faces, ie in the upper axial end face according to the representation, a recess 121 ′ into which the pump unit 1 ′ can be inserted.

[0010] The electromagnetic rotary drive with the stator 102' and the rotor 10' is designed as a so-called temple motor. The stator 102' comprises a plurality of coil cores 125', here eight coil cores 125', each of which comprises a longitudinal leg 126' and a transverse leg 127', the longitudinal leg 126' extending in the axial direction A from a first end (at Figure 1 The transverse leg 127' is arranged at the second end of the longitudinal leg 126' and in the radial plane E. Each transverse leg 127' extends in the radial direction from the associated longitudinal leg 126' towards the rotor 10' and is limited by a radial inner end face. The coil core 126' is arranged around the rotor 10' with respect to the circumferential direction so that the rotor 10' is arranged between the radial inner end faces of the transverse legs 127' of the coil core 126'.

[0011] All first ends of the longitudinal legs 126' are connected to each other via a back iron 122' for conducting magnetic flux. At least one concentrated winding 160', 161' is provided at each longitudinal leg 126', the concentrated winding 160', 161' surrounding the respective longitudinal leg 126'. With regard to the number and arrangement of the concentrated windings 160', 161', many variants are known, which are not explained in more detail here. For example, there are such windings 160' wound around exactly one longitudinal leg 126' and such windings 161' arranged around exactly two longitudinal legs 126'.

[0012] The plurality of longitudinal legs 126 ′ extending in the axial direction A and reminiscent of a temple-like column give the temple-like motor its name.

[0013] The pump unit 1' comprises a pump housing 2' having an inlet 21' and an outlet 22' for a fluid, and a rotor 10' arranged in the pump housing 2' for conveying the fluid, the rotor being rotatable about an axial direction A. The rotor 10' comprises a magnetically active core 101' which magnetically interacts with a stator 102' to form a torque and generate a magnetic bearing force. For example, the magnetically active core 101' is a permanent magnet ring or a permanent magnetic disk.

[0014] A 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 then designed, for example, as a reluctance rotor. The magnetically active core 101' of the rotor 10' is then made, for example, of a soft magnetic material. Suitable soft magnetic materials for the magnetically active core 101' are, for example, ferromagnetic or ferrimagnetic materials, i.e. in particular iron, nickel-iron, cobalt-iron, silicon-iron, μ-metal.

[0015] Furthermore, designs are possible in which the magnetically active core 101' of the rotor 10' comprises both ferromagnetic material and permanent magnet material. For example, permanent magnets may be placed or inserted into a ferromagnetic matrix. Such a design is advantageous, for example, if one wishes to reduce the cost of a large rotor by saving permanent magnet material.

[0016] Typically, the magnetically active core 101 ' is completely surrounded by plastic. In other designs, the magnetically active core 101 ' is completely surrounded in a sheath made of a ceramic material or of a metallic material, such as stainless steel or titanium or tantalum.

[0017] Furthermore, the rotor 10 ′ comprises a plurality of guide vanes 103 ′ for conveying the fluid from the inlet 21 ′ to the outlet 22 ′.

[0018] The pump housing 2' comprises a bottom part 3' and a cover 4' for closing the bottom part 3', wherein a sealing element 90', such as an O-ring or a flat seal, is arranged between the bottom part 3' and the cover 4' to prevent leakage of fluid into the environment.

[0019] The bottom part 3' of the pump housing 2' has a cylindrical cup 31' for receiving the rotor 10'. The cup 31' is inserted into a recess 121' in the motor housing 120' so that the rotor 10' (more precisely the magnetically active core 101' of the rotor 10') is arranged between the transverse legs 127' of the coil core 126'.

[0020] The pump unit 1 ' is attached to the motor housing 120', for example by means of a plurality of screws 11 '.

[0021] For many applications, for example for applications in the semiconductor industry, the pump unit 1 ' (except for the magnetically active core 101 ') is made of plastic, for example perfluoroalkoxy polymer (PFA) or polytetrafluoroethylene (PTFE), because these are plastics with a particularly high chemical resistance. These plastics are practically inert substances and cannot be attacked even by chemically very aggressive substances, such as those frequently used in the semiconductor industry. In addition, PFA and PTFE are very pure plastics, because they usually have no additional substances and their molecular complexes are at least approximately inert. PFA is generally preferred because it can be processed during injection molding.

[0022] The sealing element 90' for sealing between the bottom part 3' and the cover 4' is designed, for example, as an O-ring or an annular flat seal. For the sealing element 90', an elastomer is preferred, in particular also because elastomers have very good restoring forces. In the semiconductor industry, which places extremely high demands on purity, perfluoroelastomers (FFPM) are also often used for the sealing element 90'. FFPM is used in particular when very good heat resistance and / or chemical resistance is necessary.

[0023] Despite these very modern and high-performance materials, problems with leakage can arise, for example in the semiconductor industry. Especially at high temperatures, the chemical resistance of the elastomers may not be sufficient to ensure continuous, safe operation of the centrifugal pumps. For example, in the semiconductor industry there are processes in which sulfuric acid must be conveyed at temperatures of up to 220°C.

[0024] Another problem is the outgassing of additives, for example in sealing elements. In the semiconductor industry, for example, the smallest impurity can have fatal consequences, since the manufactured product can be unusable due to the smallest contamination. Here, it should be noted that structures in the range of 5 nanometers or even smaller are produced in the semiconductor industry today. Purity is therefore of vital importance in the semiconductor industry.

[0025] Furthermore, creep of the sealing element or parts of the sealing element may lead to problems, for example, because cracks or other damage may occur in the sealing element due to the creep process.

[0026] Particularly at relatively high temperatures and / or in the case of cyclic processes with frequent pressure or temperature changes, there is a risk of leakage, wherein very hazardous, aggressive or harmful fluids could escape into the environment of the centrifugal pump. Summary of the invention

[0027] Starting from this state of the art, the object of the present invention is therefore to propose a pump unit for a centrifugal pump having a rotor which can be magnetically suspended without contact, the pump unit having increased operational reliability, in particular with regard to leakage and with regard to purity. In addition, the object of the present invention is to propose a centrifugal pump having such a pump unit.

[0028] The subject matter of the invention which meets this object is characterized by the features of the independent patent claims.

[0029] Therefore, according to the present invention, a pump unit of a centrifugal pump for conveying fluid is proposed, the pump unit comprising a pump housing having an inlet and an outlet for the fluid, and a rotor arranged in the pump housing for conveying the fluid, the rotor being rotatable about an axial direction, wherein the pump unit is designed for contactless magnetic suspension of the rotor and for contactless magnetic drive of the rotor, wherein the pump housing has a bottom part and a cover for closing the bottom part, wherein the bottom part has a cylindrical cup for receiving the rotor and a substantially annular first sealing surface for sealing interaction with the cover, and wherein the cover has a substantially annular second sealing surface designed for sealing interaction with the first sealing surface. One of the two sealing surfaces is designed as a ribbed surface having at least one radial sealing rib extending in the circumferential direction along the entire sealing surface, while the other of the two sealing surfaces is designed as a smooth surface.

[0030] Due to this embodiment, it is possible to dispense with a separate sealing element between the bottom part and the cover, which sealing element would come into contact with the fluid during normal (i.e., malfunction-free) operation. Thus, in normal (i.e., malfunction-free) operation, the fluid to be conveyed does not come into contact with any separate sealing element, so that there is no risk of contamination of the fluid by such a separate sealing element. By dispensing with such a separate sealing element 90 ′ ( Figure 2 ), solving all those problems caused by the separate sealing element 90' in the known pump unit 1'.

[0031] The omission of such a separate sealing element is a significant improvement in terms of the purity of the fluid to be conveyed. Since the fluid cannot come into contact with such a separate sealing element during normal operation, there is also no risk of the fluid being contaminated by such a separate sealing element, for example due to leakage of additional matter from the sealing element, as might occur with, for example, an elastomeric seal.

[0032] Preferably, a radial reinforcing element is provided which is designed in an annular manner and which extends radially outwards around the two sealing surfaces. The radial reinforcing element which radially outwardly surrounds the two sealing surfaces stabilizes the first sealing surface and the second sealing surface and is therefore advantageous in preventing deformation of the sealing surfaces or movement of the two sealing surfaces relative to each other. In this way, it is ensured to an even greater extent that no gaps or other leakage paths open between the two sealing surfaces, even at higher pressures in the pump housing. In addition, the radial reinforcing element is advantageous in further reducing or even completely preventing creep of the bottom part or the cover, in particular if the pump housing is made of a plastic that is prone to creep, such as PFA or PTFE.

[0033] Preferably, several sealing ribs are arranged in the first or second sealing surface designed as a ribbed surface, each of the sealing ribs extending completely along the entire periphery of the ribbed surface. Each of these sealing ribs rests against the second or first sealing surface designed as a smooth surface. This means that each sealing rib is in direct physical contact with the sealing surface designed as a smooth surface. The term "smooth surface" particularly means that the sealing surface does not have grooves or other recesses in which the sealing ribs can engage. Therefore, the sealing ribs rest on this unstructured smooth surface.

[0034] An embodiment is possible in which the first sealing surface is designed as a ribbed surface and the second sealing surface is designed as a smooth surface, i.e. the sealing ribs are then provided at the bottom portion and the second sealing surface (i.e. the sealing surface of the cover) is unstructured and designed as a smooth sealing surface.

[0035] Furthermore, an embodiment is possible in which the second sealing surface is designed as a ribbed surface and the first sealing surface is designed as a smooth surface, i.e. the sealing ribs are then arranged at the cover and the first sealing surface (i.e. the sealing surface of the bottom part) is unstructured and designed as a smooth sealing surface.

[0036] The term "radial sealing rib" means that the sealing rib has an extension in a radial direction perpendicular to the axial direction. As a result, the sealing rib can absorb radial forces. It is not necessary, but possible, for the sealing ribs to extend perpendicular to the axial direction. They can also extend obliquely with respect to the axial direction.

[0037] In a preferred embodiment, each sealing rib is designed in each case to be circular in shape, i.e. as a circular ring extending in the circumferential direction along the entire sealing surface. This embodiment is preferred, but not essential. Embodiments are also possible in which each sealing rib is designed, for example, in an elliptical or spiral manner. The spiral embodiment is particularly advantageous for pump units in which the pump housing is designed as a volute.

[0038] Particularly preferably, each sealing rib is designed as a closed sealing rib in each case, which means that the sealing rib has no starting point and no end point. For example, each sealing rib is designed as a closed ring with no starting point and no end point relative to the circumferential direction.

[0039] The bottom part and the cover are connected to each other via a press fit, which is achieved by pressing each sealing rib of the first or second sealing surface designed as a ribbed surface against the second or first sealing surface designed as a smooth surface, thereby producing a sealed connection between the bottom part and the cover. The assembly of the cover and the bottom part is achieved in the following way: the cover and the bottom part are moved relative to each other in the axial direction so that the first sealing surface and the second sealing surface are pressed against each other so that they interact in a sealing manner. Here, an advantage is that the installation direction of the assembly of the cover and the bottom part is the axial direction, and the sealing ribs extend in the radial direction (i.e., perpendicular to the installation direction) instead of extending in the installation direction.

[0040] Preferably, the ribbed surface comprises several radial sealing ribs, for example three sealing ribs, each of which extends in the circumferential direction along the entire ribbed surface, wherein the sealing ribs are arranged adjacent to one another with respect to the axial direction and a valley is provided between two adjacent sealing ribs in each case, wherein each valley has a radial distance from the smooth surface which is different from zero, and wherein each sealing rib has a height measured in the radial direction which is greater than the radial distance of the valley from the smooth surface. Due to this embodiment, a particularly good sealing effect between the bottom part and the cover can be achieved.

[0041] Preferred measure is that radial reinforcing element is engaged in both cover and bottom part.In this way, radial reinforcing element can strengthen both cover and bottom part, can further reduce thus for example due to deformation or also the undesirable relative movement between bottom part and cover that creep effect causes.

[0042] It is a further preferred embodiment that the smooth surface is designed in a frustoconical manner. For example, if the first sealing surface is designed as a smooth surface, it can be designed in a frustoconical manner so that it tapers when viewed in the installation direction. In the case of a corresponding embodiment of the second sealing surface, the thickness of the press fit between the bottom part and the cover can then be adjusted by the depth to which the cover is pushed into the first sealing surface relative to the axial direction. It is also possible to readjust the press fit after a longer period of operation. In this way, for example, long-term creep effects can be compensated. In addition, it is easier and more material-friendly to separate the cover from the bottom part again, for example for maintenance work.

[0043] In addition, preferably, an annular safety seal is arranged between two sealing surfaces on the one hand and a radial reinforcing element on the other hand relative to the radial direction, and the safety seal prevents the escape of the fluid between the bottom part and the cover in the event of a failure. During normal (i.e., trouble-free) operation of the pump unit, the safety seal does not contact the fluid and does not have a sealing function. However, if a failure or significant malfunction occurs, so that the sealing effect between the first and second sealing surfaces is no longer fully guaranteed, the safety seal can effectively prevent the contamination of the fluid and the escape of the fluid. For example, in the semiconductor industry, such failures may have catastrophic consequences, because they may cause materials (e.g., wafers) to be unqualified, which may cause very high costs. In addition, for example, in the case of aggressive chemicals, the escape of the fluid may cause a significant risk to the environment.

[0044] However, the safety seal may also be placed in other positions, for example radially outwards with respect to the radial reinforcing elements.In embodiments with a safety seal, it is only important that the safety seal cannot come into contact with the fluid to be conveyed during normal (ie fault-free) operation.

[0045] For some applications it is advantageous to provide an axial reinforcement element on the cover for absorbing forces acting in the axial direction, wherein the axial reinforcement element is arranged in such a way that the cover is located between the axial reinforcement element and the bottom part with respect to the axial direction.

[0046] Preferably, a support structure is then provided which can be connected to the axial reinforcement element and which is arranged in such a way that the pump housing can be clamped between the axial reinforcement element and the support structure with respect to the axial direction. Preferably, the support structure is made of a metal material so that it has a high stability. The support structure can be designed, for example, as a metal mounting ring which is arranged around the cylindrical cup of the bottom part and which can be securely connected to the axial reinforcement element, for example by means of screws.

[0047] In a preferred embodiment, the motor housing of the centrifugal pump forms the support structure, and the axial reinforcement element is designed to be attached to the motor housing of the centrifugal pump. For example, the axial reinforcement element is attached to the motor housing by means of screws, so that the pump housing is clamped between the axial reinforcement element and the motor housing.

[0048] For example, axial reinforcement elements are advantageous if high pressures are to be generated with the pump unit, or if fluids are to be conveyed at high temperatures, or in the case of larger pump units generating large flow rates and / or large suction heads. Axial reinforcement elements provide the pump unit with greater stability, allowing it in particular to counteract creep effects that can be caused by axial forces.

[0049] The axial reinforcement element preferably comprises a metallic base body, for example made of stainless steel, and a sheath made of plastic, with which the base body is encapsulated.

[0050] The axial reinforcement element can also be designed to have a spring effect, for example by means of a spring washer. In this way, it is possible to readjust the sealing force between the first and second sealing surfaces.

[0051] If the pump unit is designed with an axial reinforcement element, it is an advantageous measure from a construction point of view if the axial reinforcement element is designed in one piece with the radial reinforcement element.

[0052] According to a further preferred embodiment, the bottom part comprises an annular groove which is bounded by a radially inner wall and by a radially outer wall, wherein the cover is designed for sealing engagement in the groove and wherein the radially inner wall or the radially outer wall forms the first sealing surface.

[0053] A further preferred embodiment is that an annular recess is provided in the cover, which extends radially inwards and adjacent to the second sealing surface, wherein the annular recess is separated from the second sealing surface by an annular web, so that in the operating state, the pressure of the fluid on the web strengthens the sealing interaction of the first sealing surface and the second sealing surface. Due to this embodiment, the pressure of the fluid in the pump housing in the operating state serves to generate an additional force directed radially outwards, which can increase the sealing effect between the two sealing surfaces.

[0054] As already mentioned, an embodiment is possible in which the first sealing surface is designed as a smooth sealing surface and the second sealing surface is designed as a ribbed surface.

[0055] Of course, embodiments are also possible in which the first sealing surface is designed as a ribbed surface.

[0056] Preferably, the radial reinforcement element is designed as a metal ring encapsulated by a coating of plastic. Particularly preferably, the metal ring is made of rustproof steel or stainless steel.

[0057] A particularly preferred embodiment is that the outlet for the fluid is arranged in the bottom part of the pump housing. This means that the fluid is preferably discharged from the bottom part of the pump housing.

[0058] In addition, the present invention proposes a centrifugal pump for conveying a fluid, which has a pump unit designed according to the present invention and has a drive unit, which includes a motor housing, a stator is arranged in the motor housing, and the stator together with the rotor forms an electromagnetic rotary drive for rotating the rotor around an axial direction, wherein the drive unit is designed for contactless magnetic suspension of the rotor.

[0059] Preferably, the stator is designed as a bearing and drive stator, by means of which the rotor can be magnetically driven without contact and can be magnetically suspended without contact relative to the stator, wherein the rotor is passively magnetically stabilized relative to the axial direction and actively magnetically suspended in a radial plane perpendicular to the axial direction, wherein the motor housing has a recess in the axial end face, into which recess a cylindrical cup of the pump housing can be inserted.

[0060] Particularly preferably, the electromagnetic rotary drive is designed as a temple-shaped motor, wherein the stator has a plurality of coil cores, each of the plurality of coil cores comprising a longitudinal leg and a transverse leg, the longitudinal leg extending in an axial direction from a first end to a second end, the transverse leg being arranged at the second end of the longitudinal leg and in a radial plane, and the transverse leg extending in a radial direction from the longitudinal leg, wherein the coil core is arranged around the rotor relative to the circumferential direction such that the rotor is arranged between the transverse legs of the coil core, and wherein at least one concentrated winding is provided at each longitudinal leg, which winding surrounds the corresponding longitudinal leg.

[0061] Further advantageous measures and embodiments of the invention are evident from the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In the following, the invention will be explained in more detail with reference to embodiments and with reference to the accompanying drawings, in which (partially in cross-section) the following is shown: Figure 1 : Perspective representation of a centrifugal pump according to the state of the art, partly in section, Figure 2 : From Figure 1 The cross-section of the pump unit of a centrifugal pump is represented by, Figure 3 : Cross-sectional representation of a first embodiment of a pump unit according to the invention, Figure 4 :like Figure 3 , but in exploded view, Figure 5 : From Figure 4 Details of I, Figure 6 : Cross-sectional representation of different variants for the sealing rib(s), Figure 7 : Cross-sectional representation of variants for sealing surfaces, Figure 8 : Cross-sectional representation of a variant of the first embodiment, Fig. 9 :like Figure 8 , but in exploded view, Fig.10 : Cross-sectional representation of a second embodiment of a pump unit according to the invention, Fig.11 :like Fig.10 , but in exploded view, Fig.12 : Cross-sectional representation of a variant of the second embodiment, Fig.13 :like Fig.12 , but in exploded view, Fig.14 : A cross-sectional representation of a third embodiment of a pump unit according to the invention, in an exploded view, Fig.15 : A cross-sectional representation of a fourth embodiment of a pump unit according to the invention, in an exploded view, Fig.16 : A cross-sectional representation of a fifth embodiment of a pump unit according to the invention, in an exploded view, Fig.17 : A cross-sectional representation of a sixth embodiment of a pump unit according to the invention, Fig.18 :like Fig.17 , but in exploded view, and Fig.19 : Schematic cross-sectional representation of an embodiment of a centrifugal pump according to the invention. DETAILED DESCRIPTION

[0063] As explained above, Figure 1 A centrifugal pump 200 ′ known from the prior art is shown with a rotor 10 ′ having a contactless magnetic bearing and a contactless magnetic drive. In the cross-sectional representation, Figure 2 The pump unit 1 ′ of the centrifugal pump 200 ′ is shown.

[0064] In a similar Figure 2 In the expression of Figure 3 A first embodiment of a pump unit according to the invention is shown, which is designated in its entirety by reference numeral 1. For a better understanding, Figure 4 The first embodiment of the pump unit 1 is still shown in an exploded view.

[0065] The pump unit 1 is designed as a centrifugal pump 200 for conveying a fluid (see Fig.19 ), and comprises a pump housing 2 having an inlet 21 and an outlet 22 for a fluid. A rotor 10 (in Figure 4 The rotor 10 is arranged in the pump housing 2 and forms a wheel or impeller of the pump unit 1 and thus of the centrifugal pump 200. The rotor 10 is rotatable about a desired rotation axis defining an axial direction A.

[0066] Directions perpendicular to the axial direction A are denoted radial directions. In the following, the term "axial" is used in the generally accepted meaning of "in the axial direction" or "relative to the axial direction". The term "radial" is used in the generally accepted meaning of "in the radial direction" or "relative to the axial direction".

[0067] The pump unit 1 is designed for contactless magnetic suspension of the rotor 10 and for contactless magnetic drive of the rotor 10. This can be done in particular in the same manner as in Figure 1 and Figure 2 Thus, the pump unit 1 according to the present invention can be realized in a similar manner as explained above with respect to magnetic suspension and magnetic drive. Figure 2 The pump unit 1 ′ in FIG. 1 is designed in a similar manner. For this purpose, the rotor 10 of the pump unit 1 comprises a magnetically active core 101 which is designed, for example, as a permanent magnetic ring or a permanent magnetic disk and is surrounded by a plastic sheath.

[0068] Furthermore, the rotor 10 comprises a plurality of guide vanes 103 for conveying the fluid from the inlet 21 to the outlet 22. The guide vanes 103 are arranged on the plastic jacket of the magnetically active core. The guide vanes 103 are preferably made of plastic and can, for example, be designed in one piece with the plastic jacket. Of course, it is also possible to manufacture individual guide vanes 103 or all guide vanes 103 in a separate manufacturing process and then connect them to the plastic jacket of the magnetically active core 101, for example by means of a welding process.

[0069] The impeller formed by the rotor 10 with the guide vanes 103 is preferably designed as a radial impeller, which is approached by the fluid from the inlet 21 in the axial direction A and then deflects the fluid in the radial direction.

[0070] The pump housing 2 comprises a bottom part 3 and a cover 4 for closing the bottom part 3, wherein the bottom part 3 has a cylindrical cup 31 for receiving the rotor 10. The cup 31 is preferably designed and arranged so that it can be inserted into the drive unit 100 ( Fig.19 ). In particular, this can be done in the same manner as in reference Figure 1 The cup is then arranged and designed in such a way that it can be inserted into the recess 121' ( Figure 1 ), and the magnetically active core 101 is arranged between the transverse legs 127 ′ of the coil core 125 ′.

[0071] An essential aspect for the operational safety of the pump unit 1 is a reliable sealing connection between the bottom part 3 and the cover 4, so that leakage of fluid from the interior of the pump housing 2 between the bottom part 3 and the cover 4 into the external space outside the pump housing can be reliably prevented. This sealing connection must also be ensured at high temperatures, for example up to 220° C. and / or under high pressures and / or for chemically very aggressive fluids, such as sulphuric acid.

[0072] According to the invention, for this purpose, the bottom part 3 has a first, substantially annular sealing surface 5 for sealing interaction with the cover 4, and the cover 4 has a second, substantially annular sealing surface 6 designed for sealing interaction with the first sealing surface 5. For this purpose, one of the two sealing surfaces 5 or 6 is designed as a ribbed surface with at least one radial sealing rib 7 extending in the circumferential direction along the entire sealing surface 5 or 6, while the other of the two sealing surfaces 6 or 5 is designed as a smooth surface.

[0073] exist Figure 3 and Figure 4 In the embodiment represented in , the first sealing surface 5 (ie the sealing surface 5 of the bottom part 3) is designed as a smooth surface, and the second sealing surface 6 (ie the sealing surface 6 of the cover 4) is designed as a ribbed surface.

[0074] For better understanding, Figure 5 Still showing from Figure 4 The enlarged representation of detail I makes it possible to better recognize the sealing interaction of the first sealing surface 5 and the second sealing surface 6.

[0075] Preferably, the ribbed surface comprises several (in the first embodiment exactly three) radial sealing ribs 7, each of which extends completely along the entire ribbed surface, wherein the individual sealing ribs 7 are arranged adjacent to each other with respect to the axial direction A. Each sealing rib 7 is designed as a closed circular ring. Each radial sealing rib 7 is designed in such a way that it can absorb radial forces. For this purpose, it is preferred, but not necessary, that the sealing ribs 7 are aligned vertically or at right angles to the axial direction A. An embodiment in which the sealing ribs 7 are arranged obliquely on the sealing surface 5 or 6 (i.e. at an angle different from 90° with respect to the axial direction A) is also possible. It is only essential that the radial sealing ribs 7 have sufficient extension in the radial direction to be able to absorb radial forces.

[0076] It is understood that the number of three sealing ribs 7 is to be understood as an example. More than three or less than three sealing ribs 7 can also be provided in a sealing surface 5 or 6 designed as a ribbed surface.

[0077] In both the first embodiment of the pump housing 1 according to the invention and all other embodiments described below, variants are possible in which the first sealing surface 5 is designed as a ribbed surface and the second sealing surface 6 is designed as a smooth surface. Therefore, the following two embodiments are always possible in all embodiments: namely, each sealing rib 7 is provided at the bottom part 3 and the second sealing surface at the cover 6 is designed as a smooth surface, and each sealing rib 7 is provided at the cover 4 and the first sealing surface 5 at the bottom part 3 is designed as a smooth surface. As an exemplary feature, Fig.15 An embodiment is shown in which the sealing rib 7 is arranged in the first sealing surface 5 , ie in the sealing surface 5 of the bottom part 3 .

[0078] The term "smooth surface" in one of the sealing surfaces 5, 6 means that the surface has no depressions or recesses, such as grooves, in which the sealing rib 7 can engage. Of course, it is possible that the smooth surface is deformed plastically or elastically by the sealing rib 7 (see for example Figure 5 ), but in the sealing surface 5 or 6 designed as a smooth surface, no texture or structure is provided in which the sealing rib 7 can engage, i.e., in particular, no groove. The sealing effect between the sealing surface 5 or 6 designed as a ribbed surface and the sealing surface 6 or 5 designed as a smooth surface is based on the pressure of the sealing rib 7 against the smooth surface, rather than on the engagement of the sealing rib 7 in a groove or other recess.

[0079] The pump housing 2 is preferably made of plastic. Preferred plastics are, for example, perfluoroalkoxy polymers (PFA) or polytetrafluoroethylene (PTFE), since these plastics have a particularly high chemical resistance and are not attacked or decomposed by chemically very aggressive substances, such as sulfuric acid. In addition, PFA and PTFE are particularly pure plastics, in which no additives are used, and their molecular complexes are chemically very stable, i.e., resistant to aggressive substances.

[0080] The outlet 22 for the fluid is preferably arranged in the bottom part 3 of the pump housing 2. In particular, the outlet 22 is arranged between the cup 31 and the first sealing surface 5 with respect to the axial direction A. This means that the outlet 22 is arranged according to the representation (e.g. Figure 3 , Figure 4 ) is arranged below all sealing ribs 7, regardless of whether the sealing rib 7 is arranged in the second sealing surface 6 (for example Figure 4 ) or arranged in the first sealing surface ( Fig.15 ).

[0081] The sealing rib 7 is preferably an integral part of the first or second sealing surface 5, 6. The sealing rib 7 can be produced, for example, in an injection molding process. For example, if the cover 4 and the bottom part 3 are produced in an injection molding process, the sealing rib 7 can be produced in the injection molding process by a corresponding design of the injection mold or tool. However, it is also possible to produce the sealing rib 7 by means of a subtractive machining process. The sealing rib 7 can be machined out of the first or second sealing surface 5, 6, for example, by means of machining (e.g. milling).

[0082] The sealing interaction between the first sealing surface 5 and the second sealing surface 6 is based on a press fit between the cover 4 and the bottom part 3, which Figure 5 Explain in more detail based on .

[0083] According to a preferred embodiment, the pump unit 1 also includes a radial reinforcement element 8, which is designed in an annular manner and extends radially outward around the two sealing surfaces 5, 6. Preferably, the radial reinforcement element 8 is designed as a metal ring completely surrounded by a plastic coating. For the metal ring, rustproof steel or stainless steel is preferred. For the plastic coating, highly chemically resistant plastics are preferred. Examples of such preferred plastics are PTFE, PFA, ECTFE (ethylene chlorotrifluoroethylene), PP (polypropylene), ETFE (ethylene tetrafluoroethylene), PE (polyethylene). Alternatively, it is also possible to produce the radial reinforcement element 8 completely from a firm or stable plastic.

[0084] The radial reinforcement element 8 stabilizes the two sealing surfaces 5, 6 so that the two sealing surfaces 5, 6 remain in better sealing contact with each other even at higher pressures in the pump housing 2. The radial reinforcement element 8 helps to avoid relative movements between the two sealing surfaces, which in the worst case can lead to the opening of a gap through which the fluid can escape from the pump housing 2. A further function of the radial reinforcement element 8 is to counteract creep of the bottom part 3 or the cover 4. Furthermore, the radial reinforcement element 8 can also be designed in such a way that the radial reinforcement element 8 exerts a spring effect in the radial direction towards them, which spring effect acts on the press fit between the sealing surfaces 5, 6. In this way, it is possible to adjust the press fit between the cover 4 and the bottom part 3 if the bottom part 3 or the cover 4, for example, is warped.

[0085] Preferably, the radial reinforcing element 8 is arranged so that it engages both in the cover 4 and in the bottom part 3 so that it engages on a boundary surface at which the bottom part 3 and the cover 4 rest against each other with respect to the axial direction A. For this purpose, the circumferential groove 42 ( Figure 4 ) is provided in the cover 4, and a circumferential groove 32 is provided in the bottom part 3, wherein the circumferential grooves 32, 42 are arranged such that they are aligned with each other so that in the assembled state of the pump housing 2 ( Figure 3), the circumferential grooves 32, 42 form a cavity for the radial reinforcing element 8, which surrounds the radial reinforcing element 8.

[0086] However, embodiments without radial reinforcing elements 8 are also possible (see e.g. Fig.17 , Fig.18 ).

[0087] The press fit between the cover 4 and the bottom part 3 is Figure 5 . As already mentioned, each radial sealing rib 7 is designed in a circular annular manner, wherein the individual sealing ribs 7 are arranged adjacent to one another with respect to the axial direction A. A valley 71 is provided between each two adjacent sealing ribs 7, wherein each valley 71 has a radial distance R to the sealing surface designed as a smooth surface, in this case the first sealing surface 5.

[0088] Each sealing rib 7 has a peak 72, which refers to the point of the sealing rib 7 measured in the radial direction that is farthest from the adjacent valley 71. Each sealing rib 7 has a height H, which refers to the vertical distance measured in the radial direction between the peak 72 and the adjacent valley 71. The peak 72 is connected to each of the adjacent valleys via a wall 73.

[0089] The height H of the sealing rib refers to the state when the cover 4 has not yet been assembled with the bottom part 3, i.e., for example Figure 4 After the cover has been assembled with the bottom part, i.e., for example Figure 3 In the state represented in , the sealing rib 7 is sunk into the smooth surface by, for example, deformation of the first sealing surface 5 designed as a smooth surface to a sunken depth T. Therefore, the sunken depth T indicates the difference between the position of the peak 72 measured in the radial direction and the non-deformed area of ​​the smooth surface opposite to one of the valleys 71.

[0090] In order to assemble the pump housing 2 from the bottom part 3 and the cover 4, the cover 4 is preferably brought together with the bottom part 3 in the mounting direction M until the first sealing surface 5 interacts sealingly with the second sealing surface 6. This state is achieved when the cover 4 rests on the bottom part 3. The mounting direction M is here the axial direction A. After the cover 4 has been connected to the bottom part 3 via a press fit, the cover 4 is fixed to the bottom part 3, for example by means of several fastening screws 13, which pass through the cover 4 in the axial direction A and engage in the bottom part 3.

[0091] Due to the fact that the sealing rib 7 is designed as a radial sealing rib 7 with a height H and the mounting direction M is the axial direction A, the sealing rib 7 extends transversely (e.g. perpendicularly) to the mounting direction M. This is a more advantageous design than, for example, a sealing element extending in the mounting direction (e.g. an axial sealing element).

[0092] The strength of the press fit between the cover 4 and the bottom part 3 depends inter alia on the radial distance R, the height H and the penetration depth T, wherein the penetration depth T depends inter alia on the material properties of the material or materials of which the cover 4 and the bottom part 3 are made.

[0093] In practice, it has proven that the height H is at least as large as the radial distance R, preferably larger than the radial distance R. The penetration depth T may be (at least approximately) zero, so that the sealing rib 7 rests against a smooth surface. However, it is preferred that the penetration depth T is greater than zero, so that the sealing rib 7 is sunk into the smooth surface (in this case the first sealing surface 5). The radial distance R may be (at least approximately) zero. However, it is preferred that the radial distance R is greater than zero, i.e. the diameter of the cap 4 measured at the valley 71 is smaller than the inner diameter of the smooth surface (in this case the first sealing surface 5).

[0094] The radial distance R is preferably not less than zero. If the radial distance R is less than zero, the diameter of the cover 4 measured at the valley 71 is greater than the inner diameter of the smooth surface (in this case the first sealing surface 5). If the radial distance is less than zero, this has a negative impact on the separability of the cover 4 and the bottom part 3. Such a separation may be necessary, for example, because the rotor 10 needs to be replaced.

[0095] In particular for the production of the cover 4 with the sealing rib 7 (or of course alternatively for the production of the bottom part 3 with the sealing rib 7), it is advantageous if the connection angle α between the valley 71 and the wall 73 is in each case at least 90° and preferably greater than 90°, so that undercuts are avoided in each case in the transition region between the wall 73 and the valley 71. This is particularly advantageous if the sealing rib is produced by means of an injection molding process.

[0096] Regarding the profile of the sealing rib 7 (which refers to Figure 5 ), a rounded profile is preferred because it facilitates the connection or separation of the cover 4 and the bottom portion 3. In addition, a profile in which two walls 73 of the sealing rib 7 connecting its peak 72 with two adjacent valleys 71 are symmetrical about the peak 72 is preferred.

[0097] As an exemplary feature, Figure 6Four different variants of an embodiment of the profile of the sealing rib 7 are shown in cross-section in the axial direction A. The uppermost sealing rib 7 according to the representation has a substantially triangular profile. According to the representation, the second sealing rib 7 starting from the top has a rectangular profile at its radially inner end (i.e., the position where the valley 71 is arranged). The radially outer end of the sealing rib 7 is designed with a semicircular profile, which adjoins the rectangular profile in the radial direction. According to the representation, the third sealing rib 7 starting from the top has a substantially rectangular profile, whereby the corners facing the first sealing surface 5 are each provided with a chamfer. According to the representation, the lowermost sealing rib has a rectangular profile without chamfers.

[0098] It is understood that numerous other profiles are possible for the sealing ribs 7. Embodiments are possible in which all sealing ribs 7 have the same profile on the sealing surface 5 or 6. Furthermore, embodiments are possible in which the sealing ribs 7 have at least two different profiles on the sealing surface 5 or 6.

[0099] Figure 7 A variant of the embodiment for the sealing surfaces 5 and 6 is shown. In this variant, the sealing surface 5 or 6 designed as a smooth surface (here the first sealing surface 5 as an exemplary feature) is frustoconical, i.e. designed as a shell surface of a frustoconical. Therefore, the surface normal vector of the first sealing surface 5 is no longer oriented perpendicularly to the axial direction, but encloses an angle different from 90° with the axial direction A. Here, the frustoconical body is aligned in such a way that it tapers in the mounting direction M. This means that, when viewed in the direction of the rotor 10, the diameter enclosed by the sealing surface 5 perpendicular to the axial direction A decreases. Therefore, the first sealing surface 5 forms a kind of funnel that tapers when viewed from the cover 4 in the direction of the rotor 10.

[0100] Preferably, but not necessarily, the second sealing surface 6, which is designed here as a ribbed surface with sealing ribs 7, is also designed in a frustoconical manner. The second sealing surface 6 is designed as the shell surface of a frustoconical frustum, the angle of which is more acute than the frustum of the frustum whose shell surface forms the first sealing surface 5. Due to this embodiment, the first sealing surface 5 and the second sealing surface 6 enclose a clearance angle β different from zero. Figure 7 As indicated in , the clearance angle β is the angle between the first sealing surface 5 designed as a smooth surface and a straight line extending through all valleys 71 of the second sealing surface 6. To ensure that the radial sealing effect is adequately maintained, the clearance angle β is at most 60°, and preferably less than 30°.

[0101] like Figure 7 As indicated in FIG. 1 , it is also preferred, but not necessary, that the sealing ribs 7 have different heights H. The respective heights H of the sealing ribs 7 decrease as the space enclosed by the ribbed surface (in this case the second sealing surface 6) tapers. Figure 7 , the uppermost sealing rib 7 has the largest height H, and according to , the lowermost sealing rib 7 has the smallest height H.

[0102] The advantage of such a conical embodiment of the sealing surfaces 5 and 6 is that the press fit, i.e. in particular the strength of the press fit, can be adjusted by means of the fastening screw 13. The further the cone enclosed by the second sealing surface 6 is pushed into the cone enclosed by the first sealing surface 5 in the mounting direction M by turning the fastening screw 13, the stronger the press fit between the cover 4 and the bottom part 3 becomes.

[0103] This embodiment has the advantage, among other things, that the press fit can be re-tightened, for example in the event of a long-term creep of the cover 4 and / or the bottom part 3 .

[0104] Furthermore, the conical embodiment of the sealing surfaces 5, 6 enables an easier separation of the cover 4 from the bottom part 3. The risk of damage when separating the cover 4 from the bottom part 3 counter to the mounting direction M is significantly reduced.

[0105] Other geometries of the substantially annular sealing surfaces 5, 6 are also possible, for example the two sealing surfaces 5, 6 can be designed such that they enclose an ellipsoid or such that they enclose a spiral. For such embodiments in which the pump housing 2 is designed as a volute, the latter is preferred.

[0106] In a similar Figure 3 In the cross-sectional representation of Figure 8 A variant of the first embodiment of the pump unit 1 according to the invention is shown. For a better understanding, Fig. 9 This variant is also shown in an exploded view.

[0107] exist Figure 8 and Fig. 9 In the variant represented in , an annular safety seal 20 is additionally provided, which prevents the escape of the fluid between the bottom part 3 and the cover 4 in the event of a fault. With respect to the axial direction A, the safety seal 20 is arranged in the contact surface between the bottom part 3 and the cover 4. With respect to the radial direction, the safety seal 20 is arranged between the two sealing surfaces 5, 6 on the one hand and the radial reinforcement element 8, that is, the safety seal 20 is arranged radially outward relative to the first sealing surface 5 and the second sealing surface 6. As a result, in the fault-free operating state of the pump unit 1, the safety seal 20 does not come into contact with the fluid. Due to the sealing interaction of the first sealing surface 5 and the second sealing surface 6, the fluid is impermeable until the safety seal 20, so that there is no risk of the fluid being contaminated by the safety seal 20 in turn.

[0108] However, in the event of a malfunction during operation, as a result of which the sealing effect between the two sealing surfaces 5, 6 is no longer ensured to a sufficient extent, the safety seal 20 on the one hand prevents the fluid from escaping accidentally or uncontrolled from the pump housing 2, so that, for example, aggressive or otherwise dangerous fluids cannot enter the environment or the outer space of the pump housing 2. On the other hand, in such a malfunction situation, the safety seal 20 prevents substances from entering the inner space of the pump housing from the outside, which could lead to contamination of the fluid and thus to unusability of the fluid or of products processed with the fluid, such as wafers in the semiconductor industry.

[0109] Such faults which may lead to an insufficient sealing effect of the two sealing surfaces 5 , 6 are based, for example, on creep effects, in particular long-term creep effects, or on pressure-induced and / or temperature-induced deformations, for example of the cover 4 or the bottom part 3 .

[0110] The safety seal 20 is preferably designed as an annular flat seal.

[0111] The safety seal 20 is preferably made of plastic, for example a plastic commonly used for sealing at high temperatures and / or chemically aggressive fluids. For example, the safety seal 20 may be made of the same plastic as the pump housing 2. For example, the safety seal 20 may be made of PTFE. In this case, it is preferred that the safety seal 20 is made of ePTFE (expanded PTFE), in particular because ePTFE has better elastic properties than PTFE.

[0112] Of course, it is also possible to use known elastomers for the safety seal 20. Furthermore, the safety seal may be designed as a radial or axial O-ring.

[0113] In a similar Figure 3 In the expression of Fig.10 A cross-sectional representation of a second embodiment of a pump unit 1 according to the invention is shown. For a better understanding, Fig.11 The second embodiment is also shown in an exploded view.

[0114] In the following, only the differences with the first embodiment will be discussed. The same parts of the second embodiment, or parts that are functionally equivalent, are marked with the same reference numerals as in the first embodiment. In particular, the reference numerals have the same meanings as have been explained in conjunction with the first embodiment. It is understood that all previous explanations of the first embodiment and variants also apply to the second embodiment in the same way or in a similarly identical way.

[0115] In a second embodiment of the pump unit 1 , an axial reinforcing element 9 is additionally provided on the cover 4 , which can absorb forces acting in the axial direction A. The axial reinforcing element 9 is designed here as an annular disk-shaped plate which surrounds the inlet 21 and rests on the cover 4 , so that the cover 4 is arranged between the axial reinforcing element 9 and the bottom part 3 .

[0116] Furthermore, a plurality of tensioning screws 12 are provided, each of which extends completely through the axial reinforcement element 9 and the pump housing 2 in the axial direction A, so that each tensioning screw 12 projects from the pump housing 2 below with respect to the axial direction A according to the representation. The tensioning screws 12 are designed to engage in the drive unit 100 ( Fig.19 For this purpose, a thread into which the tensioning screw 12 engages is preferably provided in the motor housing of the drive unit 100, which can be, for example, Figure 1 The motor housing 120' is designed like that in FIG.

[0117] The tensioning screws 12 are arranged radially outwardly relative to the radial reinforcement element 8. By means of the tensioning screws 12, the pump housing 2 can be clamped between the drive unit 100 and the axial reinforcement element 9, which allows the stability of the pump housing to be significantly increased with respect to the axial direction A. Such an increased stability is particularly advantageous in applications in which very high pressures are generated with the pump unit 1, or if fluids are conveyed at very high temperatures, for example 200° C. or more, or if the pump unit 1 is designed with very large dimensions. By means of the axial reinforcement element, creep caused by axial forces can be counteracted even more effectively.

[0118] As a variant, it is also possible to design the axial reinforcing element 9 to have a spring effect, for example by means of a spring washer, so that the axial reinforcing element 9 exerts a spring force, which is advantageous in order to further reduce creep of the component in the axial direction A. In doing so, a readjustment of the sealing force via which the two sealing surfaces 5, 6 interact is also possible.

[0119] The term "axial reinforcing element 9" is to be understood to mean that the axial reinforcing element 9 can absorb axial forces. However, this does not necessarily mean that the axial reinforcing element 9 must be arranged perpendicular to the axial direction A, e.g. Fig.10 and Fig.11 Embodiments in which the axial reinforcing elements are designed inclined relative to the axial direction A are also possible.

[0120] Preferably, the axial reinforcing element 9 is designed as a metal plate completely surrounded by a plastic coating. For the metal plate, rustproof steel or stainless steel is preferred. For the plastic coating, highly chemically resistant plastics are preferred. Examples of such preferred plastics are PTFE, PFA, ECTFE (ethylene chlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), PP (polypropylene), PE (polyethylene). Alternatively, it is also possible to produce the axial reinforcing element 9 completely from a strong or stable plastic.

[0121] In a similar Fig.10 In the expression of Fig.12 A cross-sectional representation of a variant of a second embodiment of a pump unit 1 according to the invention is shown. For a better understanding, Fig.13 This variant is also shown in an exploded view.

[0122] exist Fig.12 and Fig.13 In the variant shown in , the axial reinforcing elements 9 are designed in one piece with the radial reinforcing elements 8. Thus, a one-piece reinforcing element 98 is provided, which forms both the axial reinforcing elements 9 and the radial reinforcing elements 8.

[0123] The one-piece reinforcing element 98 comprises an axial reinforcing element 9 which is designed as an annular disc-shaped plate surrounding the inlet 21 and arranged on the cover 4, so that the cover 4 is arranged between the axial reinforcing element 9 and the bottom part 3. The one-piece reinforcing element 98 also comprises an annular reinforcing element 8 which is designed in an annular manner and extends radially outwards around the two sealing surfaces. The radial reinforcing element 8 is arranged in a circumferential groove 32 in the bottom part 3. The one-piece reinforcing element 98 also comprises an annular connection area 89 which connects the axial reinforcing element 9 to the radial reinforcing element 8. The annular connection area 89 adjoins the radial outer edge of the axial reinforcing element 9 and is designed so that the annular connection area 89 radially surrounds the cover 4 on the outside and rests tightly against the cover 4.

[0124] Preferably, the one-piece reinforcing element 98 is designed with a metal substrate completely surrounded by a plastic coating. For the metal substrate, rustproof steel or stainless steel is preferred. For the plastic coating, highly chemically resistant plastics are preferred. Examples of such preferred plastics are PTFE, PFA, ECTFE (ethylene chlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), PP (polypropylene), PE (polyethylene). Alternatively, it is also possible to produce the one-piece reinforcing element 98 completely from a strong or stable plastic.

[0125] The one-piece embodiment of the radial reinforcement element 8 and the axial reinforcement element 9 as a one-piece reinforcement element 98 has the advantage of particularly simple and therefore also cost-effective production. In addition, the one-piece reinforcement element 98 imparts a particularly high degree of robustness to the pump unit 1, for example because the cover 4 is completely surrounded and therefore supported along its radially outer circumferential surface, so that creep effects can be further reduced. This is also a particular advantage in applications in which fluids with high temperatures are conveyed.

[0126] It is understood that the variant with a one-piece reinforcement element 98 is also suitable for all other embodiments of the pump unit 1 according to the invention.

[0127] In a similar Fig.11 In the exploded view of Fig.14 A cross-sectional representation of a third embodiment of a pump unit 1 according to the invention is shown.

[0128] In the following, only the differences from the previously described embodiments will be discussed. The same parts of the third embodiment, or parts that are functionally equivalent, are indicated by the same reference numerals as those in the previously described embodiments. In particular, the reference numerals have the same meanings as those explained in conjunction with the previously described embodiments. It is understood that all previous explanations about the embodiments and variants also apply to the third embodiment in the same manner or in a similarly identical manner.

[0129] The third embodiment of the pump unit 1 according to the invention is similar in design to the second embodiment ( Fig.11 ). However, in the third embodiment, the circumferential groove 32 in the bottom portion of the second embodiment is replaced by an annular groove 33 which is significantly wider than the circumferential groove 32 of the second embodiment with respect to its width measured in the radial direction.

[0130] The annular groove 33 is limited by a radial inner wall 331 and a radial outer wall 332 with respect to the radial direction, wherein the radial outer wall 332 is arranged radially outwardly relative to the radial inner wall 331. Therefore, the width of the annular groove 33 is the radial distance between the radial inner wall 331 and the radial outer wall 332. The radial inner wall 331 forms the first sealing surface 5 of the bottom part 3, wherein the first sealing surface 5 is designed as a smooth sealing surface.

[0131] The cover 4 of the third embodiment is designed with an annular axial end region 44, which engages in the annular groove 33. The annular axial end region 44 is limited with respect to the radial direction by a radial inner surface 441 and by a radial outer surface 442, wherein the radial outer surface 442 is arranged radially outwardly with respect to the radial inner surface 441. The radial inner surface 441 of the axial end region 44 forms the second sealing surface 6 of the cover 4, which is designed here as a ribbed surface with sealing ribs 7.

[0132] When the axial end region 44 of the cover 4 is brought into engagement with the annular groove 33 of the bottom portion, the first sealing surface 5 formed by the radial inner wall 331 and the second sealing surface 6 formed by the radial inner surface 441 interact in a sealing manner.

[0133] The width of the annular groove 33 is dimensioned such that the annular radial reinforcing element 8 can engage into the annular groove 33 such that the radial reinforcing element 8 is arranged between the axial end region 44 and the radial outer wall 332 with respect to the radial direction.

[0134] The annular groove 33 , the axial end region 44 and the radial extension of the radial reinforcing element 8 are dimensioned in such a way that a press fit is achieved between the cover 4 and the bottom part 3 and the first sealing surface 5 interacts sealingly with the second sealing surface 6 .

[0135] According to a variant of the third embodiment of the pump unit 1, which is not represented in the drawings, the first sealing surface 5 (i.e. the sealing surface 5 of the bottom part 3) is designed as a ribbed surface with sealing ribs 7, and the second sealing surface 6 (i.e. the sealing surface 6 of the cover 4) is designed as a smooth surface. Therefore, in this variant, the radial inner wall 331 of the annular groove 33 is designed as a ribbed surface, and the radial inner surface 441 of the axial end area 44 is designed as a smooth surface.

[0136] In a similar Fig.11 In the exploded view of Fig.15 A cross-sectional representation of a fourth embodiment of a pump unit 1 according to the invention is shown.

[0137] In the following, only the differences from the previously described embodiments will be discussed. The same parts of the fourth embodiment, or parts that are functionally equivalent, are marked with the same reference numerals as those in the previously described embodiments. In particular, the reference numerals have the same meanings as those explained in conjunction with the previously described embodiments. It is understood that all previous explanations about the embodiments and variants also apply to the fourth embodiment in the same manner or in a similarly identical manner.

[0138] As already mentioned above, for the pump housing 1 according to the present invention, the following two embodiments are possible (and this also applies in particular to all embodiments described herein): an embodiment in which the first sealing surface 5 of the bottom part 3 is designed as a smooth surface and the second sealing surface 6 of the cover 4 is designed as a ribbed surface with sealing ribs 7, and an embodiment in which the first sealing surface 5 of the bottom part 3 is designed as a ribbed surface with sealing ribs 7 and the second sealing surface 6 of the cover 4 is designed as a smooth surface.

[0139] As an exemplary feature, the fourth embodiment of the pump unit 1 according to the present invention shows an embodiment in which the first sealing surface 5 is designed as a ribbed surface. Fig.11 However, in the fourth embodiment, the first sealing surface 5 (i.e. the sealing surface of the bottom portion 3) is designed as a ribbed surface with sealing ribs 7. The second sealing surface 6 (i.e. the sealing surface of the cover 4) is designed as a smooth surface.

[0140] In a similar Fig.10 In the cross-sectional representation of Fig.16 A fifth exemplary embodiment of a pump unit 1 according to the invention is shown.

[0141] In the following, only the differences from the previously described embodiments will be discussed. The same parts of the fifth embodiment, or parts that are functionally equivalent, are marked with the same reference numerals as those in the previously described embodiments. In particular, the reference numerals have the same meanings as those explained in conjunction with the previously described embodiments. It is understood that all previous explanations about the embodiments and variants also apply to the fifth embodiment in the same manner or in a similarly identical manner.

[0142] A fifth embodiment of the pump unit 1 according to the invention ( Fig.16 ) and the second embodiment ( Fig.10 ) are designed similarly.

[0143] In the fifth embodiment, an annular recess 45 is provided in the cover 4, which extends radially inwards and adjacent to the second sealing surface 6, wherein the annular recess 45 is separated from the second sealing surface 6 on its radial outer side by an annular web 46. A radially inner boundary surface 461 of the web 46 forms a radially outer boundary of the recess 45. The radially outer boundary surface of the web 46 forms the second sealing surface 6, i.e. the sealing surface 6 of the cover 4, which is designed here as a ribbed surface with sealing ribs 7. The annular recess 45 is therefore arranged at the same height as the sealing surfaces 5 and 6 with respect to the axial direction A. In the operating state of the pump unit 1, the annular recess 45 is of course also filled with fluid, so that the pressure of the fluid exerts a radially outwardly directed force on the web 46, which strengthens the sealing interaction of the first sealing surface 5 and the second sealing surface 6.

[0144] In all previously described embodiments and variants, the outlet of the pump housing is arranged in the bottom part 3. In particular, according to the representation, the outlet 22 is always arranged below the sealing rib 7, i.e., with respect to the axial direction A, the outlet 22 is arranged between the cylindrical cup 31 and the two sealing surfaces 5 and 6. This is also a preferred embodiment, i.e., all sealing ribs 7 are arranged above the outlet 22 (according to Figure 3 , Figure 4 , Figure 8-16). However, embodiments are also possible in which the separation surface between the cover 4 and the bottom part 3 is arranged significantly closer to the cylindrical cup 31 with respect to the axial direction A, so that the outlet 22 is located above the sealing rib 7 according to the representation. For example, the outlet 22 can be arranged in the cover 4.

[0145] In a similar Figure 3 In the cross-sectional representation of Fig.17 A sixth embodiment of a pump unit 1 according to the invention is shown. For a better understanding, Fig.18 A sixth embodiment of a pump unit 1 is shown, still in an exploded view.

[0146] In the following, only the differences from the previously described embodiments will be discussed. The same parts of the fifth embodiment, or parts that are functionally equivalent, are marked with the same reference numerals as those in the previously described embodiments. In particular, the reference numerals have the same meanings as those explained in conjunction with the previously described embodiments. It is understood that all previous explanations about the embodiments and variants also apply to the fifth embodiment in the same manner or in a similarly identical manner.

[0147] The sixth embodiment of the pump unit 1 according to the present invention is different from the first embodiment ( Figure 3 , Figure 4 ) is designed similarly. In contrast to the first embodiment, the sixth embodiment does not have the radial reinforcing element 8. Therefore, the sixth embodiment also does not have the circumferential grooves 32, 42 ( Figure 4 ).

[0148] Furthermore, the present invention proposes a centrifugal pump 200 for conveying a fluid having a pump unit 1, wherein the pump unit 1 is designed according to the present invention. In a schematic cross-sectional representation, Fig.19 An embodiment of a centrifugal pump 200 according to the invention is shown. The centrifugal pump 200 comprises a drive unit 100 which comprises a motor housing. For reasons of a better overview, the motor housing is not shown. Fig.19 However, the drive unit 100 may be configured as follows, for example Figure 1 The drive unit 100 ′ represented in FIG. 1 is designed in a similar manner with a motor housing 120 ′, wherein a recess 121 ′ is provided in the motor housing 120 ′, into which recess the cylindrical cup 31 of the bottom part 3 of the pump housing 1 is inserted.

[0149] The stator 102 is arranged in the motor housing and forms an electromagnetic rotary drive with the rotor 10 for rotating the rotor 10 about the axial direction A, wherein the drive unit 100 is designed for contactless magnetic levitation of the rotor 10 .

[0150] Preferably, the stator 102 is designed as a bearing and a driver stator, by means of which the rotor 10 can be magnetically driven without contact and can be magnetically suspended without contact relative to the stator 102, wherein the rotor is passively magnetically stabilized relative to the axial direction A and is actively magnetically suspended in a radial plane E perpendicular to the axial direction, i.e., controllably magnetically suspended.

[0151] Particularly preferably, the electromagnetic rotary drive with the rotor 10 and the stator 102 is designed as a temple motor, wherein the stator 102 has a plurality of coil cores 125, each of the plurality of coil cores 125 comprising a longitudinal leg 126 extending in the axial direction A from a first end to a second end and a transverse leg 127, the longitudinal leg 126 extending from a first end to a second end, the transverse leg 127 being arranged at the second end of the longitudinal leg 126 and in the radial plane E. The transverse leg 127 extends inwardly from the longitudinal leg 126 in the radial direction toward the rotor 10.

[0152] All first ends (ie the lower ends according to the representation) of the longitudinal legs 126 are connected to each other via a back iron 122 for conducting the magnetic flux.

[0153] The coil core 125 is arranged around the rotor 10 relative to the circumferential direction so 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, which surrounds the respective longitudinal leg 126.

[0154] The electromagnetic rotating fields required for the magnetic drive and magnetic suspension of the rotor 10 are generated by means of concentrated windings 160. By means of these concentrated windings 160, therefore, in the operating state those electromagnetic rotating fields are generated, by means of which a torque is achieved on the rotor 10 in a manner known per se, and by means of which arbitrarily adjustable transverse forces can be exerted on the rotor 10 in the radial direction, so that the radial position of the rotor 10, i.e. its position in a radial plane E perpendicular to the axial direction A, can be actively controlled or adjusted. With regard to the other three degrees of freedom, i.e. its position in the axial direction and the inclination relative to the radial plane E perpendicular to the desired axis of rotation (two degrees of freedom), the rotor 10 is passively magnetically suspended or magnetically stabilized by means of magnetic resistance, i.e. it cannot be controlled.

Claims

1. A pump unit of a centrifugal pump for conveying a fluid, comprising a pump housing (2) having an inlet (21) and an outlet (22) for the fluid, and a rotor (10) arranged in the pump housing (2) for conveying the fluid, the rotor being rotatable about an axial direction (A), wherein the pump unit is designed for contactless magnetic suspension of the rotor (10) and for contactless magnetic drive of the rotor (10), wherein the pump housing (2) has a bottom part (3) and a cover (4) for closing the bottom part (3), wherein the bottom part (3) has a cylindrical cup (31) for receiving the rotor (10) and a substantially annular first sealing surface (5) for sealing interaction with the cover (4), and wherein the cover (4) has a substantially annular second sealing surface (6) designed for sealing interaction with the first sealing surface (5), characterized in that One of the two sealing surfaces (5, 6) is designed as a ribbed surface having at least one radial sealing rib (7) which extends along the entire sealing surface (5, 6) in the circumferential direction, while the other of the two sealing surfaces (6, 5) is designed as a smooth surface.

2. The pump unit according to claim 1, wherein A radial reinforcing element (8) is provided which is designed in an annular manner and extends radially outwards around the two sealing surfaces (5, 6).

3. A pump unit according to any one of the preceding claims, wherein The ribbed surface comprises a plurality of radial sealing ribs (7), each of which extends in the circumferential direction along the entire ribbed surface, wherein the sealing ribs (7) are arranged adjacent to each other relative to the axial direction (A) and a valley (71) is provided between two adjacent sealing ribs (7) in each case, wherein each valley (71) has a radial distance (R) from the smooth surface that is different from zero, and wherein each sealing rib (7) has a height (H) measured in the radial direction that is greater than the radial distance (R) of the valley (71) from the smooth surface.

4. A pump unit according to any one of claims 2 to 3, wherein: The radial reinforcing element (8) is engaged both in the cover (4) and in the bottom part (3).

5. A pump unit according to any one of the preceding claims, wherein The smooth surface is designed in a frustoconical manner.

6. A pump unit according to any one of the preceding claims, wherein: An annular safety seal (20) is arranged between the two sealing surfaces (5, 6) on the one hand and the radial reinforcement element (8) on the other hand with respect to the radial direction, said safety seal preventing the escape of the fluid between the bottom part (3) and the cover (4) in the event of a malfunction.

7. A pump unit according to any one of the preceding claims, wherein An axial reinforcing element (9) is provided on the cover (4) for absorbing forces acting in the axial direction (A), wherein the axial reinforcing element (9) is arranged in such a way that the cover (4) is located between the axial reinforcing element (9) and the bottom part (3) relative to the axial direction (A).

8. The pump unit according to claim 6, wherein: The axial reinforcing element (9) is formed in one piece with the radial reinforcing element (8).

9. A pump unit according to any one of the preceding claims, wherein: The bottom part (3) comprises an annular groove (33) which is delimited by a radial inner wall (331) and by a radial outer wall (332), wherein the cover (4) is designed for sealing engagement in the groove (33), and wherein the radial inner wall (331) or the radial outer wall (332) forms the first sealing surface (5).

10. A pump unit according to any one of the preceding claims, wherein An annular recess (45) is provided in the cover (3), the recess extending radially inwardly and adjacent to the second sealing surface (6), wherein the annular recess (45) is separated from the second sealing surface (6) by an annular web (46), so that in an operating state, the pressure of the fluid on the web (46) strengthens the sealing interaction between the first sealing surface (5) and the second sealing surface (6).

11. A pump unit according to any one of the preceding claims, wherein The first sealing surface (5) is designed as the smooth sealing surface, and the second sealing surface (6) is designed as the ribbed surface.

12. A pump unit according to any one of claims 2 to 11, wherein: The radial reinforcement element (8) is designed as a metal ring encapsulated with a coating of plastic material.

13. A centrifugal pump for conveying a fluid, comprising a pump unit (1) designed according to any of the preceding claims and having a drive unit (100), the drive unit (100) comprising a motor housing, a stator (102) being arranged in the motor housing, the stator (102) forming together with the rotor (10) an electromagnetic rotary drive for rotating the rotor (10) about the axial direction (A), wherein: The drive unit (100) is designed for the contactless magnetic suspension of the rotor (10).

14. The centrifugal pump according to claim 13, wherein: The stator (102) is designed as a bearing and drive stator, by means of which the rotor (10) can be magnetically driven without contact and can be magnetically suspended without contact relative to the stator (2), wherein the rotor (10) is passively magnetically stabilized relative to the axial direction (A) and actively magnetically suspended in a radial plane (E) perpendicular to the axial direction (A), wherein the motor housing has a recess in the axial end face, into which the cylindrical cup (31) of the pump housing (1) can be inserted.

15. The centrifugal pump according to claim 14, wherein: The electromagnetic rotary drive is designed as a temple motor, wherein the stator (102) has a plurality of coil cores (125), each of the plurality of coil cores (125) comprising a longitudinal leg (125) and a transverse leg (127), the longitudinal leg (125) extending in the axial direction (A) from a first end to a second end, the transverse leg (127) being arranged at the second end of the longitudinal leg (126) and in the radial plane (E), and the transverse leg (127) extending in the radial direction from the longitudinal leg (126), wherein the coil core (125) is arranged around the rotor (10) with respect to the circumferential direction such that the rotor (10) is arranged between the transverse legs (127) of the coil core (125), and wherein at least one concentrated winding (160) is provided at each longitudinal leg (125), the winding surrounding the respective longitudinal leg (126).

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