Pump unit for centrifugal pump and centrifugal pump

Abstract

To provide a centrifugal pump unit with a magnetic non-contact rotor, which has improved operational safety with respect to leakage at high power outputs.SOLUTION: A pump unit 1 has a pump housing 2 with an inlet 21 and an outlet 22 for a fluid to be conveyed, and a rotor 10 arranged in the pump housing 2 to convey the fluid. The rotor is rotated about an axial direction A. The pump unit is designed for non-contact magnetic levitation of the rotor and non-contact magnetic drive of the rotor 10 by a stator. The pump housing 2 has a cover part 4 and a bottom part 3 to enclose the cover part 4. The bottom part 3 has a cylindrical cup to receive the rotor 10, and the cylindrical cup can be inserted into the cup-shaped recess of the stator. Both the inlet 21 and the outlet 22 of the pump housing 2 are arranged at the cover part 4.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a pump unit for a centrifugal pump according to the preamble of the independent claim. The present invention further relates to a centrifugal pump having such a pump unit.

Background Art

[0002] A centrifugal pump is known that includes a pump unit and a stator designed as a drive unit for a rotor of the pump unit, where the rotor of the pump unit forms an impeller of the centrifugal pump. The rotor within the pump unit can be magnetically supported without contact and can be driven by the stator to rotate about the axial direction without contact. Such a centrifugal pump is commercially available, for example, by the applicant under the trade name Levitronix® BPS pump.

[0003] The stator and the rotor form an electromagnetic rotary drive. For example, in the Levitronix® BPS pump, the electromagnetic rotary drive is designed according to the principle of a bearingless motor. The term bearingless motor means an electromagnetic rotary drive in which the rotor can be completely magnetically supported with respect to the stator, where no separate magnetic bearings are provided. For this purpose, the stator is designed as a bearing and drive stator that serves as both the stator of the electric drive and the stator of the magnetic bearing. On the one hand, a magnetic rotating field is generated using the electrical windings of the stator to act on the rotor with a torque that realizes its rotation about a desired axis of rotation defined by the axial direction, and on the other hand, to be able to actively control or adjust its radial position, a lateral force that can be optionally adjusted with respect to the rotor is applied. Thus, the three degrees of freedom of the rotor can be actively adjusted, i.e., its rotational position and its radial position (two degrees of freedom) can be actively adjusted. With respect to the other three degrees of freedom, i.e., its position in the axial direction and its inclination (two degrees of freedom) with respect to a radial plane perpendicular to the desired axis of rotation, the rotor is passively magnetically supported or stabilized by magnetic reluctance, i.e., the rotor cannot be controlled. The absence of a separate magnetic bearing with a complete magnetic bearing for the rotor is the characteristic that gives the bearingless motor its name. In the bearing and drive stator, the bearing function cannot be separated from the drive function.

[0004] Of course, centrifugal pumps of other designs in which the rotor is magnetically supported without contact are also known, where, for example, a separate magnetic bearing for the rotor is provided, and as a result, the magnetic bearing function is separated from the drive function. For example, a separate coil is provided for this purpose, and only the axial force for the rotor can be obtained using this separate coil, and this separate coil does not contribute to the drive of the rotor. For example, such a centrifugal pump is disclosed in WO2022 / 004144.

[0005] For example, it is known that a centrifugal pump having a rotor that is non - contact and magnetically supported and driven, such as a rotor designed according to the principle of a bearingless motor, has many applications. Due to the absence of mechanical bearings, such a centrifugal pump is suitable for applications where very delicate substances are conveyed, such as blood pumps, or in applications where there are very high purity requirements, such as the conveyance of abrasive or corrosive substances that render mechanical bearings unusable very early, for example, pumps for slurries, sulfuric acid, phosphoric acid, or other chemicals in the semiconductor industry.

[0006] FIG. 1 shows a display of a centrifugal pump known from the prior art designed according to the principle of a bearingless motor. This is, for example, the Levitronix® BPS pump. For better understanding, a part is cut away in FIG. 1 to make the interior of the centrifugal pump visible.

[0007] To indicate that the displays in FIGS. 1 and 2 are devices from the prior art, each reference sign is provided with an inverted comma or dash. The centrifugal pump is indicated as a whole by reference sign 200’.

[0008] The centrifugal pump 200’ comprises a stator 100’ and a pump unit 1’. For better understanding, the pump unit 1’ is shown in a sectional view in FIG. 2, where the section is made in the axial direction A.

[0009] A rotor 10' forming a wheel or an impeller is disposed within a pump unit 1', and fluid is conveyed using this wheel or impeller. A stator 100' has a stator housing 130' and extends in the axial direction A from a first axial end 110' to a second axial end 120'. Here, a cup-shaped recess 121' is provided at the first axial end 110', and the pump unit 1' can be inserted into the cup-shaped recess 121'. The stator 100', together with the rotor 10', forms an electromagnetic rotational drive device for rotating the rotor 10' about the axial direction A. The stator 100' is designed for a non-contact magnetic bearing of the rotor 10' according to the principle of a bearingless motor. For this purpose, the stator 100' is designed as a bearing-drive stator, and by the stator 100', the rotor 10' can be magnetically driven to rotate about the axial direction A without contact, and furthermore, can be magnetically supported with respect to the stator 100' without contact. Here, the rotor 10' is passively magnetically stabilized in the axial direction A, and furthermore, is actively magnetically supported in a radial plane perpendicular to the axial direction A, and the radial plane is indicated by line E in FIG. 1.

[0010] The electromagnetic rotational drive device having the stator 100' and the rotor 10' is designed as a so-called temple motor. The stator 100' here comprises a plurality of coil cores 125' which are eight coil cores 125'. Each of the plurality of coil cores 125' comprises a longitudinal leg 126' extending in the axial direction A from a first end which is the lower end according to the display in FIG. 1 to a second end, and a transverse leg 127' disposed at the second end of the longitudinal leg 126' within the radial plane E. Each transverse leg 127' extends radially towards the rotor 10' from the associated longitudinal leg 126' and is bounded by an end face on the radially inner side. The coil cores 126' are arranged circumferentially around the cup-shaped recess 121' and thus around the rotor 10', such that the rotor 10' will be disposed between the end faces on the radially inner side of the transverse legs 127' of the coil cores 126'.

[0011] All first ends of the transverse legs 126’ are interconnected by a back iron 122’ for conducting magnetic flux. At least one concentrated winding 160’, 161’ is provided on each longitudinal leg 126’, surrounding each longitudinal leg 126’. Regarding the number and arrangement of the concentrated windings 160’, 161’, many variants are known that are not described in detail here. For example, there are windings 160’ wound around exactly one longitudinal leg 126’ and windings 161’ wound around exactly two longitudinal legs 126’.

[0012] These plurality of longitudinal legs 126’ extending in the axial direction A and reminiscent of the columns of a temple give the name to the temple motor.

[0013] The pump unit 1’ (FIG. 2) comprises 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 the axial direction A. The rotor 10’ comprises a core 101’ having a magnetic effect that magnetically cooperates with a stator 100’ to generate a magnetic axial force in addition to generating torque. For example, the core 101’ having a magnetic effect is a permanent magnet ring or a permanent magnet disk.

[0014] It is also possible to design the core 101’ having a magnetic effect in a permanent - magnet - free manner, i.e., without using permanent magnets. In this case, the rotor 10’ is designed, for example, as a reluctance rotor. In this case, the core 101’ of the rotor 10’ having a magnetic effect is made of, for example, a soft - magnetic material. Suitable soft - magnetic materials for the core 101’ having a magnetic effect are, for example, ferromagnetic or ferrimagnetic materials such as, in particular, iron, nickel - iron, cobalt - iron, silicon iron, mu - metal, etc.

[0015] Furthermore, it is also possible to design the core 101' having the magnetic effect of the rotor 10' to include both a ferromagnetic material and a permanent magnet material. For example, the permanent magnet can be disposed or inserted into the ferromagnetic substrate. Such a design is advantageous when, for example, it is desired to save on permanent magnet material and reduce the cost of a large rotor.

[0016] Normally, the core 101' having the magnetic effect is completely covered by plastic. In other designs, the core 101' having the magnetic effect is completely enclosed within a jacket made of a ceramic material or a metallic material such as, for example, stainless steel or titanium or tantalum.

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

[0018] The pump housing 2' includes a bottom 3' and a cover portion 4' for closing the bottom 3', and here, a sealing element 90' such as, for example, an O-ring or a flat seal is provided between the bottom 3' and the cover portion 4' to prevent leakage of fluid to the environment.

[0019] The inlet 21' of the pump housing 2' is disposed within the cover portion 4' and is designed such that the fluid to be conveyed flows as a result in the axial direction A towards the rotor 10'. The outlet 22' is disposed within the bottom 3' and extends parallel to the radial plane E, that is, substantially perpendicular to the inlet 21'.

[0020] The bottom 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' within the stator housing 130' such that the rotor 10', and more precisely the core 101' having the magnetic effect of the rotor 10', is disposed between the lateral legs 127' of the coil core 126'.

[0021] For example, the pump unit 1' is attached to the stator housing 130' by attachment elements 11', such as a plurality of screws 11'. The screws 11' are arranged at the bottom 3', and fix the bottom 3' to the first axial end 110' of the stator 100'. Usually, the cover part 4' is connected to the bottom 3' via press-fitting. In addition, the cover part 4' is fixed to the bottom 3' by a plurality of mounting screws 13' that engage through the cover part 4' in the axial direction A and engage within the bottom 3.

[0022] In many applications, such as applications in the semiconductor industry, for example, the pump unit 1' is made of a plastic such as perfluoroalkoxy polymer (PFA) or polytetrafluoroethylene (PTFE), except for the core 101' having a magnetic effect, because these are plastics with very high chemical resistance. These plastics are substantially inert materials, such as substances frequently used in the semiconductor industry that cannot be attacked by chemically highly corrosive substances. In addition, PFA and PTFE are plastics with very high purity, because PFA and PTFE have no additives and their molecular complexes are at least approximately inert. Since PFA can be processed in an injection molding process, PFA is often preferred.

[0023] The sealing element 90' for sealing between the bottom 3' and the cover 4' is designed, for example, as an O-ring or a ring-shaped flat seal. In particular, an elastomer is suitable for the sealing element 90' because the elastomer has very good resilience. In the semiconductor industry where the requirements for purity are very high, it is also common to use a perfluoro-elastomer (perfluoro rubber, FFPM) for the sealing element 90'. FFPM is used especially when very high heat resistance and / or chemical resistance are required.

[0024] Despite these very new and effective materials, leakage problems can occur, especially when using a centrifugal pump designed for very high outputs, such as when using an electric rotary drive designed for outputs of 4 kW or more.

[0025] This is due, inter alia, to the fact that in applications using high pump outputs, centrifugal pumps are very often integrated into heavy piping systems, whereby large forces act on the inlets 21' and outlets 22'. These forces can lead, in particular, to distortion within the pump housing and to a creep process that can cause leakage. In addition, on the one hand, the components of the pump housing 2' must have sufficient mechanical stability and, furthermore, high strength to withstand very large forces, while on the other hand, for example, the cup 31' within the bottom 3' of the pump housing 2' should be as thin-walled as possible so as to enable the magnetic interaction between the rotor 10' and the stator 100' with the highest possible efficiency. For this reason, the manufacture of the pump unit becomes significantly more complex and costly. These conflicting requirements can only be met, if at all, by a very complex and expensive manufacturing process.

Prior Art Documents

Patent Documents

[0026]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0027] Accordingly, starting from this state of the art, the object of the present invention is to propose a pump unit having a rotor that can be magnetically levitated without contact for a centrifugal pump, which has, in particular at high outputs, an improved operating safety with respect to leakage. Furthermore, the pump unit should be as simple as possible to manufacture. In addition, the object of the present invention is to propose a centrifugal pump having such a pump unit.

Means for Solving the Problems

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

[0029] Accordingly, according to the present invention, a pump unit for a centrifugal pump is proposed, the centrifugal pump comprising 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 and the pump unit can be inserted into the cup-shaped recess, wherein the pump unit has a pump housing having an inlet and an outlet for the fluid to be conveyed and a rotor arranged in the pump housing for conveying the fluid, the rotor being rotatable about the axial direction, wherein the pump unit is designed for non-contact magnetic levitation of the rotor and for non-contact magnetic drive of the rotor by the stator, the pump housing having a cover part and a bottom for closing the cover part, the bottom having a cylindrical cup for receiving the rotor, the cylindrical cup being insertable into the cup-shaped recess of the stator. Both the inlet and the outlet of the pump housing are arranged in the cover part.

[0030] The fact that both the inlet and the outlet of the pump housing are arranged in the cover part significantly reduces the influence of the piping system connected to the inlet and the outlet with respect to potential leakage, thereby greatly improving the operating safety. For the reason that the inlet and the outlet are arranged in the cover part, the mechanical forces acting on the pump housing by the conduits or pipes connected thereto do not cause relative movement between the cover part and the bottom, and such relative movement may apply to cases where, for example, the inlet is arranged in the cover part and the outlet is arranged in the bottom. Mechanical torques such as tilt torque, shearing torque, or torsional torque, which particularly apply mechanical stress to the seal between the cover part and the bottom and reduce the operating safety particularly with respect to leakage, are significantly reduced by the arrangement according to the invention.

[0031] Furthermore, the pump unit according to the invention can be manufactured much more easily because the cover part can be specially designed for high mechanical stability and strength, while the bottom can be designed as a simple rotationally symmetric component, for example, having a thin-walled cylindrical cup. Therefore, it is no longer necessary to manufacture components such as the bottom, which has a cup that is as thin-walled as possible while having other regions of higher strength. This is a great advantage in production technology.

[0032] Preferably, the bottom can be inserted into the cover part, and as a result, the cover part surrounds the bottom on the radially outer side. This design enables the cover part to be directly supported on the stator after the pump unit is inserted into the stator, that is, this support is not realized by the bottom. This direct support of the cover part on the stator or the stator housing has the advantage that the forces exerted on the pump housing, particularly by the supply line at the heavy inlet or the discharge line at the outlet, can be transmitted to the stator better, and in particular, even if present, only a significantly reduced load is applied to the seal between the cover part and the bottom.

[0033] Regarding the design with robustness of the cover part and high strength, it is preferable that the cover part is made of a metallic material which is preferably stainless steel. Here, it is particularly preferable that this metallic material, i.e., for example stainless steel or corrosion-resistant steel, is coated with plastic or sprayed with plastic.

[0034] On the inner surface of the cover part, for example, polytetrafluoroethylene (PTFE) or perfluoroalkoxy polymer (PFA) is suitable. These plastics have particularly high chemical resistance and are thus particularly suitable for applications in the semiconductor industry. PTFE and PFA are substantially inert materials such as those frequently used in the semiconductor industry which cannot be attacked by chemically highly corrosive substances. In addition, PFA and PTFE are plastics of very high purity, because PFA and PTFE usually have no additives and their molecular complexes are at least approximately inert, and in particular because PFA and PTFE are plastics having particularly high chemical resistance.

[0035] The outer surface of the cover part is preferably coated with an epoxy resin.

[0036] The bottom having a cylindrical cup is preferably designed as a part having simple rotational symmetry. The bottom is preferably made of plastic. The bottom can be made of, for example, PFA or PTFE. The bottom can be manufactured by machining methods such as milling, for example, or by an injection molding process if the plastic such as PFA is injection moldable.

[0037] According to a preferred embodiment, an installation ring is provided on which the bottom is placed, and here, the installation ring can be fixed to the cover part such that the bottom is tightened between the installation ring and the cover part in the axial direction. This embodiment has the advantage that the cover part is firmly connected to the bottom by the installation ring, and as a result, the pump unit can be removed as a whole from the cup-shaped recess of the stator. Therefore, the pump unit can be separated from the stator by a simple method as a whole.

[0038] In a preferred embodiment, the cover part has a plurality of mounting openings for mounting elements, and the pump unit can be fixed to the stator using the mounting elements, where the mounting openings are arranged on the cover part on the radially outer side. The mounting element is designed, for example, as a screw that engages through the mounting opening and engages within the first axial end of the stator, and as a result, the cover part and thus also the pump unit can be fixed to the stator.

[0039] Particularly preferably, a radial recess is provided between two circumferentially adjacent mounting openings such that the outer diameter of the cover part at the mounting opening is larger than that at the radial recess arranged between the mounting openings. In particular, when the cover part is made of a metallic material, the eddy current loss can be significantly reduced by the radial recess. Such eddy currents can be induced in the cover part by the magnetic field generated by the stator.

[0040] Furthermore, preferably, a cover ring made of an electrically poorly conductive material is provided axially so as to be adjacent to the cover portion. This cover ring is arranged such that after the pump unit is inserted into the stator, the cover ring is disposed axially between the mounting opening and the stator. The cover ring is preferably made of a chemical-resistant plastic such as, for example, polypropylene (PP). The cover ring protects the stator. In addition, in embodiments where radial recesses are provided, the cover ring can be designed to be fitted into these radial recesses, thereby improving stability.

[0041] Specifically, when the cover portion is made of a metallic material such as, for example, corrosion-resistant steel, it is a preferred measure to provide an inner lining made of plastic on the inner surface of the cover portion. Preferably, the inner lining is made of a plastic having high chemical resistance, which is particularly resistant to corrosive substances. Examples of such plastics are PTFE, PFA, ECTFE (ethylene chlorotrifluoroethylene), ETFE (ethylene tetrafluoroethylene), or PVDE (polyvinylidene fluoride). When the plastic can be injection-molded, the metallic cover portion can advantageously function as part of an injection mold. Alternatively, it is also possible to manufacture the inner lining by inserting a plurality of plastic parts into the metallic cover portion and then welding the plurality of plastic parts together integrally.

[0042] For example, in applications using highly thermally cyclical operation, in order to more effectively prevent the inner lining from partially or completely detaching from the cover part, it is preferable that an adhering structure for improving the connection between the inner lining and the inner surface is provided on the inner surface of the cover part. These adhering structures function to engage the inner lining with the inner surface of the cover part. The adhering structure can be, for example, a notch, groove, depression, or indentation, into which the inner lining is adhered. In particular, the adhering structure can be designed to have an undercut that enables the inner lining to be engaged particularly firmly within the cover part.

[0043] Regarding the sealing between the cover part and the bottom, in a preferred embodiment, the bottom has a substantially ring-shaped first sealing surface, and the cover part has a substantially ring-shaped second sealing surface for cooperating with the first sealing surface, where the first sealing surface and the second sealing surface overlap in the axial direction, and as a result, a radial seal can be created.

[0044] In a preferred embodiment, one of the two sealing surfaces is designed as a ribbed surface having at least one radial sealing rib, and at least one radial sealing rib extends circumferentially along the entire sealing surface, while the other of the two sealing surfaces is designed as a smooth surface. This design makes it possible to omit a separate sealing element between the bottom and the cover part where the sealing element comes into contact with the fluid during normal operation, i.e., during fault-free operation. During normal operation, i.e., during fault-free operation, the fluid to be conveyed does not come into contact with any separate sealing element, and as a result, there is no risk of fluid contamination due to such a separate sealing element.

[0045] Omitting such separate sealing elements represents a significant improvement with respect to the purity of the fluid to be conveyed. Since the fluid cannot come into contact with such separate sealing elements during normal operating conditions, there is no risk of the fluid being contaminated by such separate sealing elements, for example by leakage of additives from the sealing elements, as can occur when using, for example, elastomeric seals.

[0046] Preferably, a plurality of sealing ribs are provided within the first or second sealing surface designed as a ribbed surface, each of the plurality of sealing ribs extending completely along the entire circumference of the ribbed surface. Each of these sealing ribs is in contact with 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" means, in particular, that the sealing surface does not have grooves or other recesses into which the sealing ribs can engage. Thus, the sealing ribs are placed on this unstructured smooth surface.

[0047] Embodiments are 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 provided at the bottom and the surface of the second sealing surface, i.e., the cover part, is designed without being structured as a smooth sealing surface.

[0048] Furthermore, embodiments are 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 provided on the cover part and the surface of the first sealing surface, i.e., the bottom, is designed without being structured as a smooth sealing surface.

[0049] In particular, in embodiments using radial sealing ribs or sealing ribs, it is preferred that a radially reinforcing element be provided which is designed to be ring-shaped and arranged radially inside with respect to two sealing surfaces. The radially reinforcing element arranged radially inside concentrically with the two sealing surfaces is advantageous with respect to stabilizing the first and second sealing surfaces and thus preventing deformation of the sealing surfaces or relative movement of the two sealing surfaces with respect to each other. By doing so, it is made fairly certain that there are no open gaps or other leakage paths between the two sealing surfaces even when the pressure inside the pump housing is greater. In addition, the radially reinforcing element is advantageous in further reducing or even completely preventing creep of the bottom or the cover part, especially when the bottom is made of a plastic prone to creep such as PFA or PTFE.

[0050] Regarding production technology, it is a preferred measure that the radially reinforcing element be designed as an installation ring and a single part.

[0051] Furthermore, a centrifugal pump for conveying fluid is proposed according to the present invention, having a pump unit designed according to the present invention 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, together with the rotor, forms an electromagnetic rotary drive device for rotating the rotor about the axial direction, wherein the stator is designed as a bearing drive stator, by which the rotor can be magnetically driven without contact and can be magnetically levitated with respect to the stator without contact, wherein the rotor is passively magnetically stabilized in the axial direction and actively magnetically levitated in a radial plane perpendicular to the axial direction.

[0052] Particularly preferably, the electromagnetic rotary drive device is designed as a Templ motor, the stator has a plurality of coil cores, each of the plurality of coil cores has a longitudinal leg portion extending axially from a first end portion to a second end portion, and in addition, a lateral leg portion disposed at the second end portion of the longitudinal leg portion on a radial plane, the lateral leg portion extending radially from the longitudinal leg portion, the coil cores being arranged around the rotor in a circumferential direction, as a result, the rotor being disposed between the lateral leg portions of the coil cores, at least one concentrated winding being provided on each longitudinal leg portion, and at least one concentrated winding surrounding each respective longitudinal leg portion.

[0053] Another advantageous measure and embodiment of the present invention will become apparent from the dependent claims.

[0054] Hereinafter, the present invention will be described in more detail with reference to embodiments and further with reference to the drawings.

Brief Description of the Drawings

[0055]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 14a

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0056] As already explained above, FIG. 1 shows a centrifugal pump 200' having a rotor 10' that is known from the prior art and is non-contact magnetically supported and non-contact magnetically driven. FIG. 2 shows the pump unit 1' of this centrifugal pump 200' as a cross-sectional view.

[0057] FIG. 3 shows, as an exploded perspective view, a first embodiment of the pump unit according to the present invention, which is indicated as a whole by reference numeral 1. For better understanding, FIG. 4 is a cross-sectional view similar to FIG. 2 and shows the first embodiment of the pump unit 1.

[0058] The pump unit 1 is designed for a centrifugal pump 200 (see FIG. 16) for conveying fluid and comprises a pump housing 2 having an inlet 21 and an outlet 22 for the fluid. A rotor 10 for conveying the fluid is arranged within the pump housing 2, and the rotor forms the wheel or impeller of the pump unit 1 and thus of the centrifugal pump 200. The rotor 10 can be rotated about a desired axis of rotation defining an axial direction A.

[0059] The direction perpendicular to the axial direction A is indicated as the radial direction. In the following, the term "axial direction" is used in the generally accepted meaning of "axially" or "in the axial direction". The term "radial direction" is used in the generally accepted meaning of "radially" or "in the radial direction".

[0060] The pump unit 1 is designed for the non-contact magnetic levitation of the rotor 10 and for the non-contact magnetic drive of the rotor 10. This can be realized in a manner similar to the method described in particular on the basis of FIGS. 1 and 2. Thus, the pump unit 1 according to the invention can be designed in a manner similar to the pump unit 1' in FIG. 2 with regard to magnetic levitation and magnetic drive. For this purpose, the rotor 10 of the pump unit 1 is designed, for example, as a permanent magnet ring or a permanent magnet disk and comprises a core 101 having a magnetic effect, which is surrounded by a plastic jacket 102. The plastic jacket 102 is made, for example, of PTFE or PFA.

[0061] Furthermore, the rotor 10 comprises a plurality of blades 103 for conveying the fluid from the inlet 21 to the outlet 22. The blades 103 are arranged on the plastic jacket 102 of the core 101 having a magnetic effect. The blades 103 are preferably made of plastic and can, for example, be designed as a single part with the plastic jacket 102. Of course, it is also possible to manufacture the individual blades 103 or the entire blades 103 in an individual manufacturing process and to connect the blades 103 to the plastic jacket 102 of the core 101 having a magnetic effect, for example by means of a welding process.

[0062] The impeller using the blades 103 formed by the rotor 10 is preferably designed as a radial impeller that is approached by the fluid from the inlet 21 in the axial direction A and redirects the fluid in the radial direction.

[0063] The pump housing 2 includes a cover portion 4 and a bottom portion 3 for closing the cover portion 4. Here, the bottom portion 3 has a cylindrical cup 31 for receiving the rotor 10. The cup 31 is preferably designed and arranged so as to be insertable into the cup-shaped recess 121 of the stator 100 (see, for example, FIG. 12). The stator 100 extends in the axial direction A from the first axial end 110 to the second axial end 120 and has a stator housing 130 that is substantially designed to be cylindrical. The cup-shaped recess 121 is arranged at the first axial end 110 of the stator 100 and is preferably arranged centrally on the end face forming the first axial end 110 of the stator 100. The design of the cup-shaped recess 121 and the cup 31 can be realized by a method similar to the method described based on FIG. 1. Therefore, the cup 31 is arranged and designed so as to be insertable into the recess 121' (FIG. 1) within the first axial end 110' of the stator 100', and the core 101 having a magnetic effect is arranged between the lateral legs 127' of the coil core 125'.

[0064] For example, the cover portion 4 is connected to the bottom portion 3 via press fitting. Alternatively, of course, it is also possible to weld the bottom portion 3 to the cover portion 4 for the purpose of realizing a sealed connection between the bottom portion 3 and the cover portion 4 in this way.

[0065] A sealing element 90, such as an O-ring or a flat seal, for example, is provided between the bottom 3 and the cover part 4 to prevent leakage of fluid into the environment. For the operating safety of the pump unit 1, a highly reliable sealed connection between the bottom 3 and the cover part 4 is advantageous, so that leakage of fluid from the inside of the pump housing 2 between the bottom 3 and the cover part 4 to the external space outside the pump housing 2 can be prevented with high reliability. In some applications, furthermore, this sealed connection must be made reliable even at high temperatures of, for example, up to 220 °C and / or at high pressures and / or in the case of highly corrosive fluids such as sulfuric acid.

[0066] The sealing element 90 is preferably designed as a radial sealing element 90. In an embodiment as an O-ring, for example, this means that the sealing element 90 is arranged radially between the cover part 4 and the bottom 3. In an embodiment as an axial sealing element, the sealing element is arranged between the bottom and the cover in the axial direction A. More generally, the radial sealing element 90 is arranged on a curved surface, whereas the axial sealing element is arranged on a flat surface, i.e., a non-curved surface.

[0067] Particularly because elastomers have very good resilience, elastomers are suitable for the sealing element 90. Furthermore, in the semiconductor industry, where the requirements for purity are very high, it is common to use perfluoroelastomers (perfluororubbers, FFPM) for the sealing element 90. FFPM is used particularly when very high heat resistance and / or chemical resistance are required.

[0068] According to the present invention, both the inlet 21 and the outlet 22 of the pump housing 2 are arranged in the cover part 3. Thus, in this embodiment, the separation between the cover part 4 and the bottom part 3 of the pump housing 2 is, according to this representation (Fig. 4), arranged below the outlet 22. As a result, the advantage is obtained that the cover part 4 can be designed to have very high robustness and stability and to withstand large mechanical loads, while the bottom part 3 with the cup 31 can be designed as a part with simple rotational symmetry. The bottom part 3 is preferably made of plastic. The bottom part 3 can be made, for example, of PFA or PTFE. The bottom part 3 can be manufactured, for example, by machining methods such as milling, or, in the case where plastics are injection-moldable such as PFA, by an injection molding process.

[0069] Alternatively, of course, it is also possible to make the bottom part 3 from a metallic material or a ceramic material. In particular in the case of metallic materials, materials with low conductivity are suitable in order to reduce eddy current losses. For example, titanium or nickel-based alloys known under the trade name Hastelloy are suitable.

[0070] Particularly preferably, the bottom part 3 is designed to be insertable into the cover part 4, with the result that the cover part 4 surrounds the bottom part 3 on the radially outer side. This embodiment can be recognized particularly clearly in Fig. 4. By doing so, it becomes possible for the cover part 4 to be supported directly on the stator 100 after the pump unit 1 has been inserted into the stator 100. This means that the cover part 4 comes into direct physical contact with the stator 100, with the result that the mechanical loads acting on the cover part 4 can be transmitted very well to the stator 100 or the stator housing 130. In particular, the force transmission from the pump housing 2 to the stator 100 does not occur, at least in most of it, through the bottom part 3 of the pump housing 2, but directly from the cover part 4 to the stator 100. Thus, in particular, the forces caused by a piping system connected to the inlet 21 or the outlet 22 of the pump housing 2 can also be introduced directly from the cover part 4 to the stator 100.

[0071] To attach the pump unit 1 to the stator 100, a plurality of attachment elements 11, such as a plurality of screws 11 for example, are preferably provided. The cover portion 4 includes a plurality of attachment openings 411 for the attachment elements 11, that is, for example, for the screws 11. The number of attachment openings 411 is equal to the number of attachment elements 11, and as a result, exactly one attachment opening 411 is provided for each attachment element 11.

[0072] The cover portion 4 preferably includes a radially outer flange 41 designed as a single part with the rest of the cover portion 4. The attachment openings 411 are arranged within the flange 41 such that the attachment openings 411 are arranged radially outward in the cover portion 4. Each attachment opening 41 is designed as a hole extending in the axial direction A within the flange 41, for example. In the region of the flange 41, the cover portion 4 has an inner diameter that is at least equal to the maximum outer diameter of the bottom portion 3. Thus, the bottom portion 3 can be inserted into the cover portion 4 and is surrounded radially outward by the flange 41. According to this embodiment, it is possible for the attachment element 11 to extend in the axial direction A only through the cover portion 4 and not through the bottom portion 3. By doing so, the cover portion 4 of the pump housing 2 can be fixed to the stator 100 without the attachment element 11 penetrating the bottom portion 3. In the radial direction, the bottom portion 3 is completely located within the screw 11, and the screw 11 does not engage through the bottom portion 3.

[0073] Thus, the pump unit 1 can be fixed to the stator 100 by attachment elements 11, such as screws 11 for example. Here, it is particularly advantageous that the attachment element 11 engages only through the cover portion 4 and does not engage through the bottom portion 3.

[0074] To ensure that the cover part 4 can be designed to have mechanical stability and robustness, it is preferable that the cover part 4 is made of a metal material. In particular, stainless steel or corrosion-resistant steel is preferable as the metal material. Preferably, the cover part 4 is designed as a cast part cast from stainless steel or corrosion-resistant steel. Further, for example, in order to improve the chemical resistance against corrosive substances, it is preferable that the cover part 4 is coated with plastic or sprayed with plastic on its inner surface. For example, plastics having high chemical resistance are suitable for this plastic coating. Examples of such suitable plastics are PTFE, PFA, ECTFE (ethylene chlorotrifluoroethylene), PP (polypropylene), ETFE (ethylene tetrafluoroethylene), and PE (polyethylene). Further, it is preferable that the outer surface of the cover part 4 is coated with plastic, for example, an epoxy resin.

[0075] FIG. 5 shows a perspective cross-sectional view of a second embodiment of the pump unit 1 according to the present invention as a view similar to FIG. 3. For better understanding, FIG. 6 shows a cross-sectional view similar to FIG. 4 and shows the second embodiment.

[0076] Hereinafter, only the differences from the first embodiment will be considered. The same parts or equivalent parts related to the second embodiment are denoted by the same reference numerals as those in the first embodiment. In particular, the reference numerals have the same meaning as those already described in relation to the first embodiment. It will be understood that all of the foregoing descriptions of the first embodiment are applied to the second embodiment in the same manner or in a similar manner.

[0077] In the second embodiment, an installation ring 5 is provided, and the bottom 3 is placed on the installation ring 5. The installation ring 5 can be fixed to the cover part 4 so that the bottom 3 is tightened between the installation ring 5 and the cover part 3 in the axial direction A.

[0078] In particular, as can be recognized in FIG. 6, the mounting ring 5 is arranged radially inwardly within the flange 41. The mounting ring 5 has a ring-shaped radially outer edge portion 51 and a ring-shaped support region 52 arranged radially inwardly adjacent to the ring-shaped edge portion 51. The thickness of the mounting ring 5, which means its amount of extension in the axial direction A, is greater in the region of the ring-shaped edge portion 51 than in the support region 52, so that the mounting ring has a generally L-shaped profile. In the axial direction A, the ring-shaped edge portion 51 is in contact with the cover portion 4, while the bottom portion 3 is placed on the support region 52 and is clamped between the support region 52 on one side and the cover portion 4 on the other side.

[0079] The mounting ring 5 is attached to the cover portion 4 by a plurality of mounting screws 53. As can be seen particularly clearly in FIG. 6, the mounting screws 53 are arranged radially inwardly with respect to the flange 41. Each mounting screw 53 extends in the axial direction A, engages through the cover portion 4, and engages with a thread provided within the mounting ring 5.

[0080] The embodiment using the mounting ring 5 has the advantage that the pump unit 1 can be removed entirely from the stator 100 or inserted entirely into the stator 100. Thus, it is not necessary to open the pump housing 2 for the purpose of joining the pump unit 1 and the stator 100 or for the purpose of separating the pump unit 1 and the stator 100, for example, by separating the cover portion 4 from the bottom portion 3. Further, when the pump unit 1 is removed from the cup-shaped recess 121 of the stator 100 and only the cover portion 4 is separated from the bottom portion 3, it is possible to prevent, for example, the bottom portion 3 from being held within the recess 121 by a strong magnetic force.

[0081] Furthermore, the flat pressing of the bottom portion 3 between the support region 52 of the mounting ring 5 and the cover portion 4 is advantageous because it resists the tendency of parts made of plastics such as PTFE or PFA to creep.

[0082] Suitably, the installation ring 5 is designed as a metal ring completely surrounded by a plastic coating. The metal ring is preferably made of corrosion-resistant steel or stainless steel. The plastic coating is preferably made of a plastic having high chemical resistance. Examples of such suitable plastics are PTFE, PFA, ECTFE (ethylene chlorotrifluoroethylene), PP (polypropylene), ETFE (ethylene tetrafluoroethylene), and PE (polyethylene). Alternatively, it is also possible to make the installation ring 5 entirely from a strong plastic or a stable plastic.

[0083] FIG. 7 shows, as an exploded view, a cross-sectional view through a third embodiment of the pump unit 1 according to the present invention. For better understanding, FIG. 8 shows a cross-sectional view similar to FIG. 6 showing the third embodiment.

[0084] Hereinafter, only the differences from the embodiments described above will be considered. The same or equivalent parts related to the third embodiment are denoted by the same reference numerals as those in the embodiments described above. In particular, the reference numerals have the same meaning as those already explained in relation to the above-described embodiments. It will be understood that all of the foregoing descriptions of the embodiments apply to the third embodiment in the same manner or in a similar manner.

[0085] In the third embodiment, an inner lining 44 made of plastic is provided on the inner surface of the cover portion 4. Suitably, the inner lining 44 completely covers the inner surface of the cover portion 4. The cover portion 4 is preferably made of stainless steel or corrosion-resistant steel. In this way, the inner lining 44 is provided on the inner surface of the cover portion 4.

[0086] Preferably, the inner lining is made of a plastic having high chemical resistance, for example, made of PTFE, PFA, ECTFE, PP, ETFE, PVDF, or PE.

[0087] For example, the inner lining 44 can be manufactured by injecting plastic into the cover part 4. When the plastic is injection moldable, such as PFA, the metal cover part 4 can advantageously function as part of an injection mold. Alternatively, it is also possible to manufacture the inner lining 44 by inserting a plurality of plastic parts into the metal cover part 4 and then welding the plurality of plastic parts together.

[0088] For better understanding, FIG. 9 shows a perspective view of the cover part 4 having the inner lining 44 disposed on the inner surface of the cover part 4.

[0089] As a view similar to FIG. 9, FIG. 10 shows a deformed form of the cover part 4, where the inner lining 44 is not shown in FIG. 10 for better understanding. In the deformed form shown in FIG. 10, the fixing structure 45 is disposed on the inner surface of the cover part 4, thereby improving the connection between the inner lining 44 and the inner surface of the cover part 4. These fixing structures 45 are designed to allow the inner lining 44 to engage into the inner surface of the cover part 4. These fixing structures 45 can be designed, for example, as notches, ridges, notches, grooves, depressions, or other structural parts that provide a texture on the inner surface of the cover part such that the inner lining 44 can be engaged therein. Such a fixing structure having an undercut is particularly advantageous also because such an undercut allows for a particularly firm fixing.

[0090] The fixing structure 45 has the advantage that by engaging the inner lining 44 into the inner surface of the cover part 4, partial or complete detachment of the inner lining 44 is better prevented. The risk of detachment exists especially when the inner lining is injected into the cover part 4, because the plastic used for the lining often has thermal properties such as a coefficient of expansion that are different from the metal material making up the cover part.

[0091] As an exploded view similar to FIG. 5, FIG. 11 shows a cross-sectional view through a fourth embodiment of the pump unit 1 according to the present invention. For better understanding, FIG. 12 shows the fourth embodiment in perspective view together with the stator 100 into which the pump unit can be inserted.

[0092] In the following, only the differences from the embodiments described above are considered. The same or equivalent parts related to the fourth embodiment are denoted by the same reference numerals as in the embodiments described above. In particular, the reference numerals have the same meaning as already explained in relation to the embodiments described above. It will be understood that all the foregoing descriptions of these embodiments apply to the fourth embodiment in the same manner or in a similar manner.

[0093] In the fourth embodiment, a radial recess 412 is provided between two circumferentially adjacent mounting openings 411 such that in each case the outer diameter of the cover part 4 at the mounting opening 411 is larger than at the radial recess 412 arranged between the mounting openings 411. Preferably, the radial recess 412 is designed such that substantially only individual webs 413 each extending radially remain at the radial outer flange 41 (see, for example, FIG. 3). Exactly one of the mounting openings 411 is provided in each of these webs 413. In this way, the radial recess is arranged between the webs 413 in the circumferential direction.

[0094] Such an embodiment of the cover part 4 with webs 413 is also shown in FIGS. 9 and 10.

[0095] The radial recess 412 between the webs 413 having the mounting opening 411 has the advantage that eddy current losses are significantly reduced in the operating state. Preferably, due to the cover part 4 being made of a metallic material, eddy currents are induced in the cover part 4 by the current flowing in the stator 100 in the operating state, which leads to undesirable losses. These eddy current losses can be significantly reduced by the radial recess 412.

[0096] As a further advantageous measure, a cover ring 6 made of a low-conductive material is provided. Specifically, a material having a resistivity greater than 10 5 ohm square millimeters per meter (Ω·mm 2 / m) is regarded as a low-conductive material. The cover ring 6 is arranged such that, after the pump unit 1 is inserted into the stator 100, the cover ring 6 is arranged between the mounting opening 411 and the stator 100 in the axial direction A.

[0097] The cover ring 6 has an inner diameter that is larger than the outer diameter of the installation ring 5 (if present) and further larger than the maximum outer diameter of the bottom part 3. Furthermore, the inner diameter of the cover ring 6 is dimensioned such that the web 413 can be placed on the cover ring 6. As can be particularly recognized in FIG. 11, the cover ring has a plurality of grooves 61, each of the plurality of grooves 61 extending in the radial direction, and the plurality of grooves 61 are dimensioned and arranged such that each groove 61 can receive one of the webs 413 in each case. In this embodiment using the grooves 61, the region of the cover ring 6 arranged between the grooves 61 when viewed in the circumferential direction is fitted into the radial recess 412 between the webs 413, thereby improving the stability of the pump unit 1.

[0098] In addition, the eddy current losses in the cover part 4 are further reduced by this low-conductive cover ring 6. Furthermore, the cover ring 6 functions to protect the stator 100.

[0099] In the following, a preferred embodiment for sealing between the bottom 3 and the cover part 4 will be further described based on FIGS. 13, 14 and 14a. It will be understood that these embodiments of the seal can also be realized in a similar manner in the embodiments already described.

[0100] FIG. 13 shows a cross-sectional view of a fifth embodiment of the pump unit 1 according to the invention, as a similar view to FIG. 8.

[0101] In the following, only the differences from the embodiments described above will be considered. The same or equivalent parts related to the fifth embodiment are denoted by the same reference numerals as in the embodiments described above. In particular, the reference numerals have the same meaning as already explained in relation to the embodiments described above. It will be understood that all the foregoing descriptions of these embodiments apply to the fifth embodiment in the same manner or in a similar manner.

[0102] In the fifth embodiment, a sealing element 90 designed as a radial sealing element 90 is again provided, and the radial sealing element 90 is designed as an O-ring arranged radially between the cover part 4 and the bottom 3.

[0103] In the fifth embodiment, the bottom 3 is designed such that the pressure that spreads in the pump housing 2 in the operating state generates a radially directed force acting on the radial sealing element 90, thereby reinforcing the sealing effect between the bottom 3 and the cover part 4. For this purpose, the bottom 3 is designed to have a radially outer edge 35, and the radially outer edge 35 projects beyond the cup 31 of the bottom 3 in the axial direction A, so that as a result, this outer edge 35 extends further into the cover part 4 than the cup 31. The transition region between the outer edge 35 and the cup 31 is designed to be curved. By doing so, a curved pressure surface 351 is formed, and the pressure acting inside the pump housing 2 acts on this pressure surface 351 in the operating state. This pressure generates a radially directed force component, and this radially directed force component contacts the radial sealing element 90 and presses the outer edge 35. By doing so, the sealing effect between the cover part 4 and the bottom 3 is improved.

[0104] As a view similar to FIG. 13, FIG. 14 shows a cross-sectional view of the sixth embodiment of the pump unit 1 according to the present invention. For better understanding, FIG. 14a further shows an enlarged view of detail I from FIG. 14.

[0105] In the following, only the differences from the embodiments described above will be considered. The same parts or equivalent parts related to the sixth embodiment are denoted by the same reference numerals as those in the embodiments described above. In particular, the reference numerals have the same meaning as those already described in relation to the embodiments described above. It will be understood that all of the foregoing descriptions of these embodiments apply to the sixth embodiment in the same manner or in a similar manner.

[0106] In the sixth embodiment, no separate separating element 90 is provided between the bottom 3 and the cover part 4.

[0107] In the sixth embodiment, the bottom 3 comprises a substantially ring-shaped first sealing surface 91 for cooperating in a sealed manner with the cover part 4, and the cover part 4 comprises a substantially ring-shaped second sealing surface 92 for cooperating with the first sealing surface 91, where the first sealing surface 91 and the second sealing surface 92 overlap in the axial direction, so that a radial seal can be created. If the cover part 4 is designed to have an inner lining 44 as shown in FIG. 14, the second sealing surface 92 is provided on the inner lining 44. In the sixth embodiment, the first sealing surface 91 is arranged on the radially outer edge 35 of the bottom 3.

[0108] For cooperating in a sealed manner, one of the two sealing surfaces 91 or 92 is designed as a ribbed surface having at least one radial sealing rib 97 extending circumferentially along the whole of the sealing surface 91 or 92, while the other of the two sealing surfaces 91 or 92 is designed as a smooth surface.

[0109] In the sixth embodiment shown in FIGS. 14 and 14a, the first sealing surface 91, i.e. the sealing surface 91 of the bottom 3, is designed as a ribbed surface, and the second sealing surface 92, i.e. the sealing surface 92 of the cover 4, is designed as a smooth surface.

[0110] Preferably, the ribbed surface comprises a plurality of radial sealing ribs 97 which are exactly three in number in the sixth embodiment, each of the plurality of radial sealing ribs 97 extending completely along the whole of the ribbed surface, where the individual sealing ribs 97 are arranged adjacent to one another in the axial direction A. Each sealing rib 97 is designed as a closed circular ring. Each radial sealing rib 97 is designed to be able to absorb radial forces. For this purpose, although not essential, preferably the sealing rib 97 is aligned perpendicular or at right angles to the axial direction A. Embodiments are also possible in which the sealing rib 97 is arranged obliquely on the sealing surface 91 or 92, i.e. at an angle different from 90° with respect to the axial direction A. It only matters that the radial sealing rib 97 has a sufficient radial extension range to enable it to absorb radial forces.

[0111] It should be understood that the number of the three sealing ribs 97 is to be regarded as an example. Four or more or less than three sealing ribs 97 may also be provided on the sealing surface 91 or 92 designed as a ribbed surface.

[0112] Regarding the sealing rib 97, a modified form in which the second sealing surface 92 is designed as a ribbed surface and the first sealing surface 91 is designed as a smooth surface is of course possible. Therefore, both embodiments are possible, that is, an embodiment in which each sealing rib 97 is provided on the bottom 3 and the second sealing surface 92 of the cover portion 4 is designed as a smooth surface, and an embodiment in which each sealing rib 97 is provided on the cover portion 4 and the first sealing surface 91 of the bottom 3 is designed as a smooth surface.

[0113] The expression that one of the sealing surfaces 91, 92 is designed as a "smooth surface" means that this surface has no indentations or recesses such as grooves into which the sealing rib 97 can engage. Of course, it is also possible for the smooth surface to be plastically or elastically deformed by the sealing rib 97, but in the sealing surface 91 or 92 designed as a smooth surface, no texture or structural portion into which the sealing rib 7 can engage is provided, that is, no groove is provided in particular. The sealing effect between the sealing surface 91 or 92 designed as a ribbed surface and the sealing surface 92 or 91 designed as a smooth surface is not based on the engagement of the sealing rib 97 in a groove or other recess, but on the pressure of the sealing rib 97 on the smooth surface.

[0114] The sealing rib 97 is preferably an integral part of the first sealing surface 91 or the second sealing surface 92. The sealing rib 97 can be made, for example, in an injection molding process. For example, if the bottom 3 is made in an injection molding process, the sealing rib 97 can be made in this injection molding process according to the corresponding design of the injection mold or tool. However, it is also possible to make the sealing rib 97 by a subtractive machining process. For example, the sealing rib 97 can be elaborately made from the first sealing surface 91 or the second sealing surface 92 by machining such as milling as an example.

[0115] The sealing cooperation between the first sealing surface 91 and the second sealing surface 92 is based on the press fit between the cover part 4 and the bottom 3, which will be described in more detail based on FIG. 14a.

[0116] Optionally, but preferably, the pump unit 1 is designed in a ring shape and further comprises a radial reinforcing element 98 arranged radially inside with respect to the two sealing surfaces 91, 92. Preferably, the radial reinforcing element 98 is designed as a metal ring completely surrounded by a plastic coating. Corrosion-resistant steel or stainless steel is suitable for the metal ring. A plastic with high chemical resistance is suitable for the plastic coating. Examples of such suitable plastics are PTFE, PFA, ECTFE, PP, ETFE, PE. Alternatively, it is also possible to manufacture the radial reinforcing element 98 entirely from high-strength plastic or stable plastic.

[0117] In the sixth embodiment, the radial reinforcement element 98 is arranged within the radially outer edge 35, and in particular stabilizes the first sealing surface 91, such that the first sealing surface 91 maintains a better sealing contact with the second sealing surface 92 even when the pressure within the pump housing 2 is higher. The radial reinforcement element 98 contributes to avoiding relative movement between the two sealing surfaces 91, 92, which could lead to creating a gap through which fluid could escape from the pump housing 2 in the worst case scenario. A further function of the radial reinforcement element 98 is to resist creep of the bottom 3 in particular. Furthermore, the radial reinforcement element 98 can also be designed to exert a radial spring effect outwards so as to influence the press fit between the sealing surfaces 91, 92. By doing so, it becomes possible to adjust the press fit between the cover part 4 and the bottom 3 when the bottom 3 is distorted for example.

[0118] In an embodiment in which the pump unit 1 is designed to have the mounting ring 5, it is a preferred measure that the radial reinforcement element 98 is designed as a single part with the mounting ring 5. FIG. 14 shows such an embodiment in which the radial reinforcement element 98 is designed as a single part with the mounting ring.

[0119] Optionally, a ring-shaped safety seal 99 is additionally provided to prevent fluid leakage between the bottom 3 and the cover part 4 in the event of a failure. The safety seal 99 is here designed as an axial sealing washer arranged axially between the mounting ring 5 and the cover part 4. The safety seal 99 is arranged radially adjacent to the two sealing surfaces 91, 92 and radially outside the two sealing surfaces 91, 92. As a result, the safety seal 99 does not come into contact with the fluid in the fault-free operating state of the pump unit 1. Due to the sealing cooperation of the first sealing surface 91 with the second sealing surface 6, the fluid cannot penetrate up to the safety seal 99, and as a result, conversely, there is no risk of the fluid being contaminated by the safety seal 99.

[0120] However, if a failure occurs during operation and as a result the sealing effect between the two sealing surfaces 91, 92 is not ensured to a sufficient extent, on the one hand, the safety seal 99 prevents fluid from escaping unintentionally or uncontrollably from the pump housing 2, so that, for example, corrosive fluid or other dangerous fluids cannot leak into the environment or the external space of the pump housing 2. If such a failure occurs, on the other hand, the safety seal 99 prevents substances from entering the internal space of the pump housing from the outside, which can lead to fluid contamination and thus to the unusability of the fluid or products processed with the fluid, such as wafers in the semiconductor industry for example.

[0121] Such a failure, which can render the sealing effect by the two sealing surfaces 5, 6 insufficient, can be based, for example, on the creep effect, in particular the long-term creep effect, of the cover part 4 or the bottom part 3 as an example, or on pressure-induced deformation and / or temperature-induced deformation.

[0122] The safety seal 99 is preferably designed as a ring-shaped flat seal.

[0123] The safety seal 99 is preferably made of plastic, such as plastic that is commonly used to seal high-temperature and / or chemically corrosive fluids for example. For example, the safety seal 99 can be made of PTFE. In this case, preferably the safety seal is made of ePTFE (expanded PTFE), which is in particular because ePTFE has better elastic properties than PTFE. Of course, it is also possible to use known elastomers for the safety seal 99.

[0124] The press fit between the cover part 4 and the bottom part 3 is shown in the enlarged view of Detail I in Fig. 14a. As already mentioned, each radial sealing rib 97 is designed to be in a circular ring shape, and here, the individual sealing ribs 97 are arranged adjacent to each other in the axial direction A. A valley portion 971 is provided between two adjacent sealing ribs 97 in each case, and here, each valley portion 971 has a radial distance R from a sealing surface designed as a smooth surface, which is the second sealing surface 92 in this case.

[0125] Each sealing rib 97 has a peak portion 972 that means the position of the sealing rib 97 that is farthest from the adjacent valley portions 971 measured in the radial direction. Each sealing rib 97 has a height H that means the vertical distance measured between the peak portion 972 and the adjacent valley portion 971 in the radial direction. The peak portion 972 is connected to the adjacent valley portion in each case via a wall 973.

[0126] The height H of the sealing rib means the state when the bottom part 3 has not yet been inserted into the cover part 4. After the bottom part 3 is inserted into the cover part 4, that is, in the state represented by Fig. 14 for example, the sealing rib 97 penetrates into the smooth surface by an intrusion depth T due to the deformation of the second sealing surface 92 designed as a smooth surface, for example. Therefore, the intrusion depth T indicates the difference between the position of the peak portion 972 measured in the radial direction and the non-deformed region of the smooth surface facing one of the valley portions 971.

[0127] The strength of the press fit between the cover part 4 and the bottom part 3 is determined, among other things, by the radial distance R, the height H, and the intrusion depth T. Here, the intrusion depth T is determined, in particular, by the material properties of the materials making up the cover part 4 and the bottom part 3 or by the materials.

[0128] In practice, it has been found that the height H is at least as large as the radial distance R, and preferably larger than the radial distance R. The penetration depth T can be (at least approximately) zero, so that the sealing rib 97 is in contact with the smooth surface. However, it is preferred that the penetration depth T is greater than zero, so that the sealing rib 97 penetrates into the smooth surface. The radial distance R can be (at least approximately) zero. However, preferably the radial distance R is greater than zero.

[0129] Preferably, the radial distance R is not less than zero. If the radial distance R is less than zero, the diameter of the bottom 3 measured at the trough 971 is larger than the inner diameter of the smooth surface which is the second sealing surface 92 in this case. If the radial distance is less than zero, this has an adverse effect on the separability of the bottom 3 from the cover part 4. Such separation may be essential, for example, because it is necessary to replace the rotor 10.

[0130] For the particularly high-reliability non-contact magnetic levitation of the rotor 10, and in particular for the particularly good passive magnetic levitation or stabilization of the rotor 10, certain regions are suitable for the geometric design of the rotor 10 and for the arrangement of the outlet 22 of the pump housing 2. This will be explained in more detail below with reference to FIG. 15.

[0131] FIG. 15 shows the first embodiment again in a display similar to FIG. 4, where various dimensions to be described below are shown. It should be understood that these descriptions of the dimensions are not only applicable to the first embodiment, but are also applied in a similar manner to all other embodiments and variants of the pump unit 1 according to the present invention.

[0132] Outlet 22 has an immersion surface 220, where the immersion surface 220 means the surface through which fluid flows from the internal space of the pump housing 2 into the outlet 22 (see also Fig. 10). The immersion surface 220 of the outlet 22 is designed as, for example, an ellipse. Specifically, the immersion surface 220 is designed as an ellipse with a symmetry axis S, where the symmetry axis S is perpendicular to the axial direction A. The immersion surface 220 is arranged on the cover part 4.

[0133] Inlet 21 has an exudation surface 210, where the exudation surface 210 means the surface through which fluid flows from the inlet 21 into the internal space of the pump housing 2. The exudation surface 210 of the inlet 21 is designed as, for example, a circular surface with a diameter DE. The exudation surface 210 of the inlet 21 is arranged on the cover part 4.

[0134] The rotor 10 includes a core 101 having a magnetic effect, a plastic jacket 102, and blades 103 arranged on the plastic jacket 102. The rotor 10 has a diameter DU, where the diameter DU here means the diameter DU of the plastic jacket 102 that surrounds the core 101 having a magnetic effect. The plastic jacket 102 further has a height HU, which means the extent of the plastic jacket 102 extending in the axial direction A. Thus, the height HU corresponds to the height of the rotor 10 measured in the axial direction A, reduced by the height of the blades 103.

[0135] Each blade 103 has a central axis FM, which means a center line perpendicular to the axial direction A. The central axis FM divides each blade 103 into two parts of equal height with respect to the axial direction A. The central axes FM of all the blades 103 all lie in a plane, where this plane is perpendicular to the axial direction A. The central axis FM of the blade 103 has an exudation distance FA from the symmetry axis S of the immersion surface 220 of the outlet 22.

[0136] In particular, with regard to the best possible magnetic stabilization of the rotor 10 with respect to the inclination, it is advantageous for the penetration distance FA of the symmetry axis S of the penetration surface 220 of the outlet 22 from the central axis FM of the blade 103 to be as small as possible. Furthermore, it is preferable for the ratio of the penetration distance FA to the diameter DU of the plastic jacket 102 to be less than 0.26, and particularly preferably less than 0.21.

[0137] In particular, with regard to the axial stability of the rotor 10, that is, with regard to the passive magnetic stabilization of the rotor 10 with respect to the axial direction A, it is preferable for the ratio of the diameter DE of the penetration surface 210 of the inlet 21 to the diameter DU of the plastic jacket 102 to be between 0.25 and 0.99, and particularly preferably between 0.31 and 0.83.

[0138] With regard to the dimensions of the plastic jacket 102, it is preferable for the ratio of the height HU of the plastic jacket 102 to the diameter DU of the plastic jacket 102 to be between 0.31 and 0.79, and particularly preferably between 0.39 and 0.65.

[0139] Furthermore, a centrifugal pump 200 for transporting fluid using the pump unit 1 is proposed by the present invention, where the pump unit 1 is designed according to the present invention. As a schematic cross-sectional view, FIG. 16 shows an embodiment of the centrifugal pump 200 according to the present invention. The centrifugal pump 200 includes a stator 100 extending in the axial direction A from a first axial end 110 to a second axial end 120. Here, a cup-shaped recess 121 (not shown in FIG. 16, see FIG. 12 for example) is provided at the first axial end 110, and the cylindrical cup 31 of the pump unit 1 can be inserted into the cup-shaped recess 121. The stator 100, together with the rotor 10, forms an electromagnetic rotary drive device for rotating the rotor 10 about the axial direction A. Here, the stator 100 is designed as a bearing-driving stator, and by the stator 100, the rotor 10 can be magnetically driven without contact and magnetically levitated with respect to the stator 100 without contact. Here, the rotor 10 is passively magnetically stabilized in the axial direction A and actively magnetically levitated in the radial plane E perpendicular to the axial direction A.

[0140] The stator 100 includes a stator housing 130 (see FIG. 12), and the stator housing 130 is not shown in FIG. 16 for better overview. However, the stator 100 can be designed in a similar manner to the stator 100' having the stator housing 130' represented in FIG. 1, for example. Here, a recess 121' is provided in the stator housing 130', and the cylindrical cup 31 at the bottom 3 of the pump housing 1 is inserted into the recess 121'.

[0141] Particularly preferably, the electromagnetic rotary drive device having the rotor 10 and the stator 100 is designed as a temple motor. Here, the stator 100 has a plurality of coil cores 125, and each of the plurality of coil cores 125 includes a longitudinal leg 126 extending in the axial direction A from a first end to a second end, and in addition, a transverse leg 127 disposed at the second end of the longitudinal leg 126 in the radial plane E. The transverse leg 127 extends radially inward from the longitudinal leg 126 toward the rotor 10.

[0142] All the first ends of the longitudinal legs 126, i.e., the lower ends according to this illustration, are connected to each other by a back iron 122 for conducting magnetic flux.

[0143] The coil core 125 is arranged around the rotor 10 in the circumferential direction, and as a result, the rotor 10 is arranged between the lateral legs 127 of the coil core 125. At least one concentrated winding 160 is provided on each longitudinal leg 126, and the concentrated winding 160 surrounds each longitudinal leg 126.

[0144] An electromagnetic field necessary for the magnetic drive and magnetic levitation of the rotor 10 is generated by the concentrated windings 160. Thus, by using these concentrated windings 160, such an electromagnetic field is generated in the operating state to act torque on the rotor 10 in a manner known per se, and furthermore, an optionally adjustable lateral force can be made to act radially on the rotor 10 by using such a rotating electromagnetic field, and as a result, the radial position of the rotor 10, i.e., its position in the radial plane E perpendicular to the axial direction A, is actively controlled or adjusted. With respect to the other three degrees of freedom, i.e., its position in the axial direction A and its inclination (two degrees of freedom) with respect to the radial plane E perpendicular to the desired axis of rotation, the rotor 10 is passively magnetically levitated or stabilized by magnetic reluctance, i.e., the rotor 10 cannot be controlled.

Claims

1. In a pump unit for a centrifugal pump comprising a pump unit, and a stator (100) extending axially (A) from a first axial end (110) to a second axial end (120), a cup-shaped recess (121) is provided at the first axial end (110), the pump unit (1) can be inserted into the cup-shaped recess (121), a pump housing (2) having an inlet (21) and an outlet (22) for a fluid through which the pump unit is to be conveyed, and a rotor (10) disposed within the pump housing (2) for conveying the fluid, the rotor can be rotated about the axial direction (A), the pump unit is designed for non-contact magnetic levitation of the rotor (10) and for non-contact magnetic drive of the rotor (10) by the stator (100), the pump housing (2) has a cover portion (4) and a bottom (3) for closing the cover portion (4), the bottom (3) has a cylindrical cup (31) for receiving the rotor (10), and the cylindrical cup can be inserted into the cup-shaped recess (121) of the stator (100), the pump unit, characterized in that both the inlet (21) and the outlet (22) of the pump housing (2) are disposed in the cover portion (4).

2. The pump unit according to claim 1, wherein the bottom (3) can be inserted into the cover portion (4), such that the cover portion (4) surrounds the bottom (3) radially outwardly.

3. The pump unit according to any one of claims 1 to 2, wherein the cover portion (4) is made of a metallic material, preferably stainless steel.

4. An installation ring (5) is provided, the bottom (3) is placed on the installation ring (5), and the installation ring (5) can be fixed to the cover portion (4) such that the bottom (3) is clamped between the installation ring (5) and the cover portion (4) in the axial direction (A). The pump unit according to any one of claims 1 to 3.

5. The cover part (4) has a plurality of mounting openings (411) for mounting elements (11), the pump unit can be fixed to the stator (100) using the mounting elements (11), and the mounting openings (411) are arranged radially outside on the cover part (4). The pump unit according to any one of claims 1 to 4.

6. A radially concave portion (412) is provided between two adjacent mounting openings (411) in the circumferential direction such that the outer diameter of the cover part (3) at the mounting openings (411) is larger than that at the radially concave portion (412) arranged between the mounting openings (411). The pump unit according to claim 5.

7. A cover ring (6) made of a low-conductive material is provided axially (A) adjacent to the cover part (4), and the cover ring is arranged such that after the pump unit is inserted into the stator, the cover ring (6) is arranged between the mounting openings (411) and the stator (100) in the axial direction (A). The pump unit according to any one of claims 4 to 7.

8. An inner lining (44) is provided on the inner surface of the cover part (4), and the inner lining is made of plastic. The pump unit according to any one of claims 1 to 7.

9. An adhering structure (45) is provided on the inner surface of the cover part (4), and the adhering structure improves the connection between the inner lining (44) and the inner surface. The pump unit according to claim 8.

10. The bottom part (3) has a substantially ring-shaped first sealing surface (91), the cover part (4) has a substantially ring-shaped second sealing surface (92) for cooperating with the first sealing surface (91), and the first sealing surface (91) and the second sealing surface (92) overlap in the axial direction (A), so that a radial seal can be produced. The pump unit according to any one of claims 1 to 9.

11. One of the two sealed surfaces (91, 92) is designed as a ribbed surface having at least one radial sealing rib (97), the at least one radial sealing rib (97) extending circumferentially along the entire sealed surface (91, 92), while the other of the two sealed surfaces (92, 91) is designed as a smooth surface, the pump unit according to claim 10.

12. The pump unit according to claim 11, wherein a radial reinforcing element (98) is provided which is designed to be ring-shaped and arranged radially inside with respect to the two sealed surfaces (91, 92).

13. The pump unit according to claim 12 and claim 4, wherein the radial reinforcing element (98) is designed as a single part with the mounting ring (5).

14. A centrifugal pump for conveying fluid, having a pump unit designed according to any one of claims 1 to 13, and having a stator (100) extending axially (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), the cylindrical cup (31) of the pump unit (1) can be inserted into the cup-shaped recess (121), the stator (100) forms an electromagnetic rotary drive device for rotating the rotor (10) about the axial direction (A) together with the rotor (10), the stator (100) is designed as a bearing / drive stator, the rotor (10) can be magnetically driven without contacting the stator (100), can be magnetically levitated with respect to the stator (100) without contacting, the rotor (10) is passively magnetically stabilized in the axial direction (A), and is actively magnetically levitated in a radial plane (E) perpendicular to the axial direction (A).

15. The electromagnetic rotary drive device is designed as a Templ motor, the stator (100) has a plurality of coil cores (125), each of the plurality of coil cores (125) has a longitudinal leg (126) extending in the axial direction (A) from a first end to a second end, and a transverse leg (127) arranged at the second end of the longitudinal leg (126) in the radial plane (E), the transverse leg (127) extending radially from the longitudinal leg (126), the coil cores (125) being arranged around the rotor (10) in the circumferential direction, so that the rotor (10) is arranged between the transverse legs (127) of the coil cores (125), at least one concentrated winding (160) is provided on each longitudinal leg (125), and the at least one concentrated winding (160) surrounds the respective longitudinal leg (126), the centrifugal pump according to claim 14.

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