Pump unit for centrifugal pump and centrifugal pump
Patent Information
- Application Number
- CN202510473683.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-04-30
- Filing Date
- 2025-04-16
- Publication Date
- 2025-10-31
Smart Images
Figure CN120868068A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a pump unit for a centrifugal pump according to the preamble of an independent patent claim. The invention further relates to a centrifugal pump having such a pump unit. Background Technology
[0002] Centrifugal pumps are known, comprising a pump unit and a stator of a drive unit designed for the rotor of the pump unit, wherein the rotor of the pump unit forms the centrifugal wheel of the centrifugal pump. The rotor can be magnetically supported without contact and can be driven without contact by means of the stator in the pump unit to rotate about an axial direction. Such centrifugal pumps are, for example, produced by the applicant under the product name... The pump is sold on the market.
[0003] The stator and rotor form an electromagnetic rotary drive. For example, in In pumps, electromagnetic rotary actuators are designed based on the principle of bearingless motors. The term bearingless motor refers to an electromagnetic rotary actuator in which the rotor is fully magnetically supported relative to the stator, without individual magnetic bearings. For this purpose, the stator is designed as both a bearing and a drive stator, serving as both the stator for the electric drive and the stator for the magnetic bearings. A magnetic rotating field can be generated using the electrical windings of the stator. This magnetic rotating field applies torque to the rotor, enabling rotation about a desired axis of rotation defined by the axial direction. Furthermore, this magnetic rotating field applies an adjustable lateral force to the rotor, allowing active control or adjustment of the rotor's radial position. Thus, three degrees of freedom of the rotor—its rotation and its radial position (two degrees of freedom)—can be actively adjusted. Regarding the other three degrees of freedom—its position in the axial direction and its tilt relative to a radial plane perpendicular to the desired axis of rotation (two degrees of freedom)—the rotor is passively magnetically supported or stabilized by magnetic resistance; that is, it cannot be controlled. The absence of individual magnetic bearings with complete magnetic bearings is a characteristic that gives rise to the name "bearingless motor." In bearings and drive stators, the bearing function cannot be separated from the drive function.
[0004] Of course, other centrifugal pump designs are also known, in which the rotor is magnetically supported without contact, such as those designs in which separate magnetic bearings are provided for the rotor, thus separating the magnetic bearing function from the drive function. For example, separate coils are provided for this purpose, which are used only to achieve the bearing force for the rotor, but these coils do not contribute to the drive of the rotor. For example, such a centrifugal pump is disclosed in WO 2022 / 004144.
[0005] Centrifugal pumps with non-contact magnetically supported and magnetically driven rotors (such as those designed and operated based on the principle of bearingless motors) have proven themselves in a wide range of applications. Due to the absence of mechanical bearings, such centrifugal pumps are suitable for applications involving the transport of highly sensitive substances, such as blood pumps, or applications with very high purity requirements, such as in the semiconductor, pharmaceutical, and biotechnology industries. They are also suitable for applications transporting abrasive or corrosive substances that would very quickly damage mechanical bearings, such as pumps for slurries, sulfuric acid, phosphoric acid, or other chemicals in the semiconductor industry.
[0006] Figure 1 This illustrates a centrifugal pump designed based on the principle of a bearingless motor, as known from the current level of technology. For example, this is... Pump. To better understand, in Figure 1 The section has been removed, making the interior of the centrifugal pump visible.
[0007] Centrifugal pump 200' includes stator 100' and pump unit 1'. For better understanding, Figure 2 A top view of pump unit 1' as seen from the axial direction A is shown, and Figure 3 Along Figure 2 The cross-sectional view along section line III-III shows pump unit 1'.
[0008] For instructions Figure 1 , Figure 2 and Figure 3 The references in the text refer to equipment of the current technological level, and each reference is marked here using either a backtick or a dash. Centrifugal pumps are indicated by reference 200'.
[0009] Rotor 10' is arranged in pump unit 1', forming a centrifugal wheel or impeller for conveying fluid. Stator 100' has stator housing 130' and extends in the axial direction A from a first axial end 110' to a second axial end 120', wherein a cup-shaped recess 121' is provided at the first axial end 110', into which pump unit 1' can be inserted. Stator 100' together with rotor 10' forms an electromagnetic rotary actuator for rotating rotor 10' about axial direction A. According to the principle of bearingless motor, stator 100' is designed as a non-contact magnetic bearing for rotor 10'. For this purpose, the stator 100' is designed as a bearing and driver stator, by which the rotor 10' can be magnetically driven without contact for rotation about the axial direction A, and can be magnetically supported without contact relative to the stator 100', wherein the rotor 10' is passively magnetically stable relative to the axial direction A, and actively magnetically supported in a radial plane perpendicular to the axial direction A, the radial plane being formed by... Figure 1 Line E in the diagram indicates this.
[0010] The electromagnetic rotary actuator, having a stator 100' and a rotor 10', is designed as a so-called temple-shaped motor. The stator 100' includes a plurality of coil cores 125', here eight coil cores 125', each of the coil cores 125' including a longitudinal leg 126' and a transverse leg 127', the longitudinal leg 126' extending in the axial direction A from the first end (at... Figure 1 The lower end (as indicated) extends to the second end, with lateral legs 127' arranged at the second end of the longitudinal legs 126' and in the radial plane E. Each lateral leg 127' extends radially from the associated longitudinal leg 126' toward the rotor 10' and is defined by a radially inwardly positioned end surface. The coil core 126' is arranged relative to the circumferential direction around the cup-shaped recess 121' and thus around the rotor 10', such that the rotor 10' is arranged between the radially inwardly positioned end surfaces of the lateral legs 127' of the coil core 126'.
[0011] All the 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 at least one concentrated winding 160', 161' surrounding the corresponding longitudinal leg 126'. Many variations are known regarding the number and arrangement of the concentrated windings 160', 161', which will not be explained in more detail here. For example, there are such windings 160' that are wound around exactly one longitudinal leg 126' and such windings 161' that are arranged around exactly two longitudinal legs 126'.
[0012] The temple-shaped motor is named for its multiple longitudinal legs 126' extending in the axial direction A and reminiscent of temple columns.
[0013] Pump unit 1' ( Figure 2 , Figure 3 The system includes a pump housing 2' having an inlet 21' and an outlet 22' for conveying the fluid, and a rotor 10' arranged within the pump housing 2' for conveying the fluid, the rotor being rotatable about an axial direction A. The pump housing 2' defines a pump chamber 23'. The rotor 10' includes a magnetic active core 101' that magnetically cooperates with the stator 100' to generate torque and magnetic bearing force. For example, the magnetic active core 101' is a permanent magnet ring or a permanent magnet disk.
[0014] In operation, the desired position of rotor 10' is centered relative to axial direction A and also centered in radial plane E between coil cores 125' (here, the lateral support legs 127' of coil core 125'). Centering relative to axial direction A means that the magnetic active core 101' of the rotor is aligned with the lateral support legs 127' of coil core 125'. The magnetic center plane of rotor 10' (which is typically the geometric center plane of magnetic active core 101') then lies in radial plane E. If rotor 10' deflects out of this centered desired position in the axial direction or tilts against axial direction A, this creates a magnetic restoring force that moves rotor 10' back to its desired position.
[0015] Such a design is also possible, in which the effective magnetic core 101' is designed in a manner without permanent magnets, i.e., without permanent magnets. The rotor 10' is then designed as, for example, a reluctance rotor. The effective magnetic core 101' of the rotor 10' is then made of, for example, a soft magnetic material. Suitable soft magnetic materials for the effective magnetic core 101' are, for example, ferromagnetic or ferrimagnetic materials, i.e., particularly iron, nickel-iron, cobalt-iron, silicon-iron, and μ metals.
[0016] Furthermore, it is possible for the effective magnetic core 101' of the rotor 10' to include both ferromagnetic and permanent magnet materials. For example, permanent magnets can be placed or inserted into a ferromagnetic matrix. Such a design is advantageous, for example, if one wishes to reduce the cost of a large rotor by saving permanent magnet material.
[0017] Typically, the active magnetic core 101' is completely encapsulated in plastic. In other designs, the active magnetic core 101' is completely enclosed in a sheath made of ceramic or metallic materials, such as stainless steel, titanium, or tantalum.
[0018] In addition, the rotor 10' includes a plurality of guide vanes 103' for conveying fluid from inlet 21' to outlet 22'.
[0019] The pump housing 2' includes a bottom component 3' and a cover component 4' for closing the bottom component 3', wherein a sealing element 90' is provided between the bottom component 3' and the cover component 4'. Figure 1 For example, O-rings or flat seals are used to prevent fluid from leaking into the environment.
[0020] The inlet 21' of the pump housing 2' is arranged in the cover member 4' and is designed such that the fluid to be pumped flows toward the rotor 10' in the axial direction A. The outlet 22' extends parallel to the radial plane E, that is, extends substantially perpendicular to the inlet 21'. Typically, the inlet 21' is designed such that it forms a rounded transition into the pump chamber 23'.
[0021] The bottom part 3' of the pump housing 2' has a cylindrical cup-shaped portion 31' for receiving the rotor 10'. The cup-shaped portion 31' is inserted into a recess 121' in the stator housing 130', such that the rotor 10' (more precisely, the magnetic active core 101' of the rotor 10') is arranged between the transverse legs 127' of the coil core 126'.
[0022] For example, pump unit 1' is attached to stator housing 130' by means of attachment elements 11' (e.g., multiple screws 11'). Screws 11' are arranged at bottom member 3' and secure bottom member 3' to the first axial end 110' of stator 100'. Typically, cover member 4' is connected to bottom member 3' via press fit. Alternatively, cover member 4' is secured to bottom member 3' by means of several attachment screws 13', which pass through cover member 4' in the axial direction A and engage in bottom member 3'.
[0023] For many applications, such as those in the semiconductor industry, pump unit 1' (except for the magnetic active core 101') is made of plastic (e.g., perfluoroalkoxy polymer (PFA) or polytetrafluoroethylene (PTFE)) because these are plastics with particularly high chemical resistance. These plastics are practically inert materials, and even chemically highly corrosive substances, such as those frequently used in the semiconductor industry, cannot be corroded by them. Furthermore, PFA and PTFE are very pure plastics because they typically contain no additives, and their molecular complexes are at least nearly inert. PFA is generally preferred because it can be processed during injection molding.
[0024] Although this type of pump unit 1' and centrifugal pump 200' has proven very successful in practice, there is still room for improvement, especially when these centrifugal pumps 200' are designed for very high outputs. Particularly under high hydraulic outputs, high leakage flow occurs, which is guided from the trailing edge of guide vane 103' in the direction of inlet 21'. The leakage flow... Figure 3 The arrow in the middle indicates this without a reference mark. This leakage flow reduces the efficiency of the centrifugal pump, and therefore, of course, its energy efficiency as well. Additionally, the leakage flow causes a stripping effect, particularly in the inlet region, which can lead to cavitation and further reductions in efficiency. Summary of the Invention
[0025] Therefore, starting from the prior art, the object of the present invention is to provide a pump unit with a rotor for a centrifugal pump, the rotor being magnetically levitated without contact, which, in particular but not only, achieves very high efficiency of the centrifugal pump under high hydraulic output. Furthermore, the object of the present invention is to provide a centrifugal pump having such a pump unit.
[0026] The subject matter of the invention that satisfies this purpose is characterized by the features of the independent patent claims.
[0027] Therefore, according to the present invention, a pump unit for a centrifugal pump is provided, the centrifugal pump comprising a 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 into which the pump unit can be inserted, wherein the pump unit has a pump housing and a rotor arranged in the pump housing, the pump housing having an inlet and an outlet for a fluid to be conveyed, the rotor having a plurality of guide vanes for conveying the fluid, wherein each guide vane extends axially to an inlet-facing end face of the rotor, wherein the pump housing defines a pump chamber, wherein the rotor is rotatable about the axial direction, wherein the pump unit is designed for non-contact magnetic levitation and non-contact magnetic drive of the rotor by means of the stator, wherein the pump housing has a cover member and a bottom member, wherein the bottom member has a cylindrical cup-shaped portion for receiving the rotor, the cup-shaped portion being insertable into the cup-shaped recess of the stator. The inlet has a lip that forms an axial end of the inlet, wherein the lip protrudes into the pump chamber and terminates in front of the end face of the rotor when viewed in the flow direction and when the rotor is centered relative to the axial direction in the operating state.
[0028] Therefore, if the rotor is in its desired position during operation, i.e., centered relative to the axial direction, then when viewed in the axial direction, the lip is a certain distance from the rotor's end face, preventing the lip from protruding into the rotor. Of course, due to the rotor's magnetic levitation, the rotor may shift axially as a whole during operation. Due to this axial shift, depending on the lip design, the lip may sink into the rotor relative to the axial direction during operation. Therefore, the statement that the lip terminates in front of the rotor's end face relative to the axial direction when viewed in the flow direction refers to an operating state where the rotor is centered relative to the axial direction, i.e., the rotor is in its desired position.
[0029] A lip forming an axial end of the inlet and protruding into the pump chamber significantly reduces leakage flow from the trailing edge of the guide vane in the direction of inlet 21 because the lip reduces the free-flow cross-section for this leakage flow as it protrudes into the pump chamber. Alternatively, the lip allows for a higher design of the pump chamber relative to the axial direction without increasing the free-flow cross-section for the leakage flow. Furthermore, the lip forms a clearly defined stripping edge for the fluid flowing through the inlet. This defined stripping edge determines the location of the stripping at the inlet, regardless of the specific properties of the fluid (such as its viscosity) and specific flow conditions (such as flow velocity). Because leakage flow from the trailing edge of the guide vane to the inlet of the pump housing is significantly reduced, the efficiency of the centrifugal pump increases. Furthermore, the stripping effect caused by the leakage flow (which can, for example, cause cavitation) is at least significantly reduced.
[0030] By reducing leakage flow, the disturbance forces acting on the rotor in the radial direction are also significantly reduced. In doing so, the current required for the rotor's active radial magnetic levitation is also reduced, which improves the efficiency and energy efficiency of the centrifugal pump.
[0031] Another advantage of the lip that acts as the stripping edge is that the static and dynamic axial directional forces on the rotor are reduced because the suction effect on the cover components of the pump housing is minimized.
[0032] Because the inlet lip protrudes into the pump chamber, a valve-like effect is also created at the inlet. This is beneficial to the axial stability of the rotor, both in terms of rotor tilt and axial displacement.
[0033] Preferably, the lip is designed in a ring shape and extends along the entire periphery of the entrance relative to the circumferential direction. However, embodiments are also possible in which the lip has one or more gaps when viewed in the circumferential direction. For example, the lip can be designed in a serrated manner. Thus, the lip can be designed to have an interruption relative to the circumferential direction.
[0034] According to a preferred embodiment, guide vanes of the rotor are arranged around a central inlet region that extends axially to the end face of the rotor and has a diameter. The central inlet region of the rotor has no guide vanes. Each guide vane extends from a radially inwardly arranged leading edge to a radially outwardly arranged trailing edge. The leading edge of the guide vane lies on a line (preferably a circular line) that has a distance other than zero from the central axis of the rotor. The diameter of the central inlet region is determined by the distance of the leading edge of the guide vane from the central axis of the rotor. The diameter of the central inlet region is equal to twice the distance of the leading edge of the guide vane from the central axis of the rotor.
[0035] Furthermore, preferably, the rotor has at least one vent opening extending axially through the rotor from the central inlet region. This central vent opening reduces the axial thrust acting on the rotor.
[0036] According to a preferred embodiment, the lip of the inlet has an outer diameter larger than the diameter of the central inlet region. However, embodiments in which the outer diameter of the lip is smaller than the inner diameter of the central inlet region are also possible. In these embodiments, it is then possible that, due to axial displacement of the rotor, the lip enters the central inlet region of the rotor in the operating state.
[0037] According to a preferred embodiment, the lip has a substantially triangular profile, with its apex facing the end face of the rotor. As a result, the rotor-facing end of the inlet is designed with a narrow edge, which is advantageous in terms of its function as a stripping edge. It is understood that, in the case of a substantially triangular profile, the apex is not designed as a sharp edge, i.e., not in the sense of a blade, but rather as an edge with a finite width.
[0038] Furthermore, a preferred measure is that the lip widens when viewed in the flow direction. Therefore, the cross-sectional area of the lip increases when viewed in the flow direction. For example, the lip can be designed to taper with respect to the axial direction.
[0039] It is also possible to design the lip edge to curve outwards.
[0040] Another possible embodiment is that the lip is designed as a cylindrical tube section.
[0041] According to another embodiment, the cover component of the pump housing is designed in an inclined manner, such that the cover component surrounds an angle greater than 90° in the axial direction at the inlet.
[0042] According to another preferred embodiment, the outlet has an inlet surface through which fluid flows from the pump chamber into the outlet, wherein the inlet surface of the outlet has a profile different from that of a circular surface. Due to this embodiment of the inlet surface of the outlet, the distance measured in the axial direction between the inlet surface and the guide vane can be significantly reduced without having to reduce the cross-sectional area of the inlet surface. Because the profile of the inlet surface of the outlet is different from that of a circular surface, the inlet surface can be arranged to be closer to the guide vane in the axial direction than a circular profile of the inlet surface, without reducing the cross-sectional area of the inlet surface.
[0043] For example, if an entry surface with a circular profile and a defined diameter is compared with an entry surface with a non-circular profile, the entry surface with a non-circular profile can be designed to have a larger cross-sectional area than the entry surface with a circular profile, while the maximum extension of the entry surface with a non-circular profile is no greater than the defined diameter of the entry surface with a circular profile.
[0044] Conversely, this means that an entry surface with a non-circular profile can be designed to have the same cross-sectional area but a smaller extension, particularly in the axial direction, compared to an entry surface with a circular profile. Therefore, an entry surface with a non-circular profile can be arranged closer to the guide vanes or have a greater overlap with them relative to the axial direction. This has a particularly advantageous effect on the non-contact magnetic levitation of the rotor, as the static and dynamic axial and tilting forces on the rotor, as well as the disturbance forces acting on the rotor in the radial direction, are significantly reduced.
[0045] According to a preferred embodiment, the profile of the surface entering the surface is designed in a substantially rectangular manner.
[0046] Furthermore, particularly for reasons of manufacturing technology, a preferred embodiment is that the profile of the entry surface is designed to have rounded corners.
[0047] According to a preferred embodiment, the profile entering the surface has a profile height in the axial direction and a profile width in the radial direction perpendicular to the axial direction, wherein the profile width is greater than the profile height.
[0048] Furthermore, the present invention proposes a centrifugal pump for conveying fluids, having a pump unit designed according to the 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, into which a cylindrical cup-shaped portion of the pump unit can be inserted, wherein the stator and rotor together form an electromagnetic rotary actuator for rotating the rotor about the axial direction, wherein the stator is designed as a bearing and actuator stator, by means of which the rotor can be magnetically driven without contact and magnetically levitated without contact relative to the stator, wherein the rotor is passively magnetically stable relative to the axial direction and actively magnetically levitated in a radial plane perpendicular to the axial direction.
[0049] Particularly preferably, the electromagnetic rotary actuator is designed as a temple-shaped motor, wherein the stator has a plurality of coil cores, each of which includes a longitudinal leg and a transverse leg, the longitudinal leg extending axially 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 radially from the longitudinal leg, wherein the coil cores are arranged relative to the circumferential direction around the rotor such that the rotor is arranged between the transverse legs of the coil cores, and wherein at least one concentrated winding is provided at each longitudinal leg, the winding surrounding the corresponding longitudinal leg.
[0050] Further advantages and embodiments of the invention will be apparent from the dependent claims. Attached Figure Description
[0051] The invention will be explained in more detail below with reference to embodiments and the accompanying drawings. The schematic drawings show (partially in cross-section):
[0052] Figure 1 A perspective view of a centrifugal pump based on current technology, partially in cross-section.
[0053] Figure 2 Top view of the pump unit viewed from the axial direction A.
[0054] Figure 3 Along Figure 2The section view from section line III-III in the middle Figure 2 pump unit,
[0055] Figure 4 A first embodiment of the pump unit according to the invention in a cross-sectional view along the axial direction.
[0056] Figure 5-8 , Figure 8A For different variations of the first embodiment, each variation corresponds to Figure 4 In the view of the view,
[0057] Figure 9 A second embodiment of the pump unit according to the invention in a cross-sectional view along the axial direction.
[0058] Figure 10 The first variant of the profile of the inlet surface for the outlet.
[0059] Figure 11 : A second variant of the profile of the entry surface for the exit, and
[0060] Figure 12 : A schematic cross-sectional view of an embodiment of the centrifugal pump according to the present invention. Detailed Implementation
[0061] As explained above, Figure 1 A centrifugal pump 200' known from the prior art is shown, which has a rotor 10' that is non-contact magnetically supported and non-contact magnetically driven. Figure 2 and Figure 3 Pump unit 1' of the centrifugal pump 200' is shown in both top view and cross-sectional view.
[0062] In corresponding Figure 3 In the cross-sectional view, Figure 4 A first embodiment of the pump unit according to the invention is shown, which is indicated by reference numeral 1 in its entirety.
[0063] Pump unit 1 is designed for use with centrifugal pump 200 for conveying fluids (see...) Figure 12 The pump unit 1 comprises a pump housing 2 having an inlet 21 and an outlet 22 for fluid. A rotor 10 for conveying fluid is arranged in the pump housing 2, which forms the centrifugal wheel or impeller of the pump unit 1 and thus the centrifugal wheel or impeller of the centrifugal pump 200. The rotor 10 is rotatable about a desired axis of rotation defining an axial direction A. This desired axis of rotation is the central axis M of the rotor 10.
[0064] Relative to the axial direction A, the rotor 10 extends from the end face 107 facing the inlet 21 to the back side away from the inlet 21.
[0065] The direction perpendicular to the axial direction A is designated as the radial direction. In the following text, the term "axial" is used in its commonly accepted meaning "in the axial direction" or "relative to the axial direction." The term "radial" is used in its commonly accepted meaning "in the radial direction" or "relative to the axial direction."
[0066] Pump unit 1 is designed for non-contact magnetic levitation of rotor 10 and for non-contact magnetic drive of rotor 10. This can be particularly compatible with... Figures 1 to 3 The explanation based on this is similar to the implementation in the same way. Therefore, the pump unit 1 according to the invention can be magnetically levitated and magnetically driven to... Figure 3 The pump unit 1' is designed in a similar manner. For this purpose, the rotor 10 of the pump unit 1 includes a magnetic active core 101, which is designed as, for example, a permanent magnet ring or a permanent magnet disk and is surrounded by a sheath 102. The sheath 102 is preferably designed as a plastic sheath. The sheath 102 is made, for example, of PTFE or PFA. The magnetic active core 101 is encapsulated in the sheath 102, that is, the sheath 102 completely and preferably hermetically surrounds the magnetic active core 101. As a result, the magnetic active core 101 is protected from the influence of fluids. The sheath 102 can be produced, for example, by spraying plastic around the magnetic active core 101.
[0067] The effective magnetic core 101 of the rotor 10 is this component of the rotor 10, which magnetically cooperates with the stator 100 to generate torque and generate magnetic levitation force.
[0068] Furthermore, the rotor 10 includes a plurality of guide vanes 103 for conveying fluid from inlet 21 to outlet 22. The guide vanes 103 are arranged on the sheath 102 of the magnetic active core 101. The guide vanes 103 are preferably made of plastic and may, for example, be designed as a single piece with the sheath 102. Alternatively, individual guide vanes 103 or all guide vanes 103 may be manufactured in a separate manufacturing process and then attached to the sheath 102 of the magnetic active core 101, for example, by means of a welding process.
[0069] The impeller formed by the rotor 10 with guide vanes 103 is preferably designed as a radial impeller, which is approached by fluid from the inlet 21 in the axial direction A and then redirected in the radial direction.
[0070] Pump housing 2 includes a cover component 4 and a bottom component 3 that are connected to each other in a sealing manner, which in Figure 4 The details are not shown in greater detail here, as this is not necessary for understanding the invention. The bottom component 3 includes a cylindrical cup-shaped portion 31 for receiving the rotor 10. The cup-shaped portion 31 is preferably designed and arranged such that it can be inserted into a cup-shaped recess in the stator 100, as... Figure 12 It is illustrated in the diagram.
[0071] Stator 100 ( Figure 12 It extends from the first axial end 110 to the second axial end 120 in the axial direction A, and has a stator housing. Figure 12 (Not shown in the image), the stator housing is designed in a substantially cylindrical manner. A cup-shaped recess is arranged at the first axial end 110 of the stator 100, preferably centrally located in the end surface forming the first axial end 110 of the stator 100. The design of the stator housing with the cup-shaped recess can be particularly suitable for use with stators based on… Figure 1 The implementation is similar to that explained for the stator housing 130' and the cup-shaped recess 121'. Therefore, the cup-shaped portion 31 is then arranged and designed such that it can be inserted into the recess 121' in the first axial end 110' of the stator 100'. Figure 1 In the coil core 125', the magnetic active core 101 is arranged between the transverse legs 127' of the coil core 125'.
[0072] As in Figure 4 As can be understood, according to the diagram, a pump chamber 23 exists above the cup-shaped portion 31, the pump chamber 23 is defined by the pump housing 2, and the guide vanes 103 of the rotor 10 are arranged in the pump chamber 23. The pump chamber 23 is designed at least substantially cylindrically, wherein the diameter of the pump chamber 23 is larger than the inner diameter of the cup-shaped portion 31. As a result, the pump housing 2 has a flange-like protrusion 24, which, according to the diagram, defines the pump chamber 23 downward relative to the axial direction A.
[0073] The inlet 21 is centrally located in the cover component 3 of the pump housing 2, allowing fluid to flow toward the rotor 10 in the axial direction A.
[0074] Each guide vane 103 extends from a radially inwardly arranged leading edge 109 to a radially outwardly arranged trailing edge 108. In the embodiment described herein, the guide vanes 103 are designed with exemplary features such that they extend in a straight line from the leading edge 109 to the trailing edge 108 in the radial direction and have a constant height over their entire extension. Here, height refers to the extension of the guide vane 103 in the axial direction A. As already mentioned, this design will be understood as illustrative only. In other embodiments, the guide vanes 103 are designed, for example, to be curved relative to the radial direction, and / or have a height that changes from the leading edge 109 to the trailing edge 108 in the axial direction A. For example, Figure 12 The following embodiment is shown: wherein the guide vane 103 has a greater height at its leading edge 109 than at its trailing edge 108.
[0075] Additionally, an annular cover plate 8 may be optionally provided, which is arranged on the upper edge of the guide vanes 103 facing the inlet 21. The cover plate 8 covers all guide vanes 103. Relative to the radial direction, the annular cover plate 8 extends from the leading edge 109 of the guide vanes 103 to their trailing edge 108. Here, the cover plate 8 forms the end face 107 of the rotor 10. If the rotor 10 is designed without the cover plate 8, the upper edge of the guide vanes 103 facing the inlet forms the end face of the rotor 10.
[0076] Guide vanes 103 of rotor 10 are arranged around the central inlet region 25, which does not have guide vanes 103. The leading edge 109 of guide vanes 103 lies on a line having a distance from the central axis M of rotor 10 other than zero, here on a circular line. The diameter D1 of the central inlet region 25 is determined by the distance of the leading edge 109 of guide vanes 103 from the central axis M of rotor 10. This diameter D1 of the central inlet region 25 is equal to twice the distance of the leading edge 109 of guide vanes 103 from the central axis of rotor 10. In the embodiment described herein, the diameter D1 of the central inlet region 25 is the same as the inner diameter of the annular cover plate 8. Relative to the axial direction A, the central inlet region 25 extends along the leading edge 109 of guide vanes 103 to the end face 107 of rotor 10.
[0077] For example, if the leading edge 109 of the guide vane does not extend parallel to the axial direction A but is inclined relative to the axial direction A, the diameter D1 of the central inlet region 25 is determined by the distance of the leading edge 109 at the upper edge of the guide vane 103 facing the inlet 21.
[0078] Furthermore, the rotor 10 includes a vent opening 104, which is cylindrical in design and extends in the axial direction A. The vent opening 104 is centrally located in the rotor 10 such that its axis coincides with the central axis M of the rotor 10. The vent opening 104 extends from the central inlet region 25 through the rotor 10 and to the back side of the rotor 10 in the axial direction A.
[0079] The outlet 22 has an inlet surface 221 and an exit surface (in) Figure 4 (Not visible in the middle), fluid can flow through the inlet surface 221 out of the pump chamber 23 and into the outlet 22, and the fluid leaves the outlet 22 through the exit surface. As is usually the case, the profile of the inlet region 221 refers to the cross-sectional area perpendicular to the main flow direction of the fluid in the outlet 22. Figure 4 As shown in the diagram, the profile of the inlet surface 221 is a circular surface. The profile of the inlet surface 221 is the vertical projection of the inlet surface 221 onto a plane perpendicular to the flow direction of the fluid in the outlet 22.
[0080] According to the invention, the inlet 21 includes a lip 28 forming an axial end of the inlet 21, wherein, when the rotor 10 is centered relative to the axial direction A in the operating state, the lip 28 protrudes into the pump chamber 23 and is spaced apart from the end face 107 of the rotor 10 relative to the axial direction A. When viewed in the direction of fluid flow, the lip 28 terminates in front of the end face 107 of the rotor 10. The lip 28 is preferably designed in a ring-like manner.
[0081] Due to the magnetic levitation of rotor 10, the rotor may, in operation, naturally shift axially as a whole. In this case, rotor 10 could shift in axial direction A, causing the distance between lip 28 and end face 107 to become zero, or lip 28 to even sink into the central inlet region 25 of rotor 10. Therefore, the characteristic that lip 28 terminates at a certain distance from end face 107 refers to the state when rotor 10 is in its desired position relative to axial direction A, such that rotor 10 is centered relative to stator 100 relative to axial direction A. In the accompanying drawings, rotor 10 is always indicated in this centered position relative to axial direction A.
[0082] In the following text, the distance of the lip 28 from the end face 107 of the rotor 10 in the axial direction is referred to as the lip distance DL. Therefore, the lip distance DL refers to the operating state when the rotor 10 is centered relative to the axial direction A.
[0083] The lip 28 serves as a stripping edge for the fluid flowing into the pump chamber 23. Due to the lip 28, there is a clearly defined location where fluid stripping occurs. In this way, the negative stripping effects that lead to cavitation and reduced efficiency can be significantly reduced. It is understood that, when viewed in the circumferential direction, the lip 28 need not be designed in a continuous manner, but can also be designed to have interruptions.
[0084] Another effect of the lip 28 protruding into the pump chamber 23 is that it significantly reduces the leakage flow from the trailing edge 108 of the guide vane in the direction of the inlet 21. The lip 28 reduces the free-flow cross-section between the trailing edge 108 of the guide vane and the inlet 21. Due to this reduction in the cross-section through which the leakage flow can pass, the leakage flow is also reduced, resulting in less fluid flowing back to the inlet from the trailing edge 108 of the guide vane 103 per unit time. This reduction in leakage flow increases the efficiency of the centrifugal pump 200, and therefore also increases its energy efficiency.
[0085] exist Figure 4In the first embodiment shown, the lip 28 has a triangular profile, with the vertices of the triangular profile facing the end face 107 of the rotor 10. The lip 28 has a depth T in the axial direction A, which indicates how far the lip 28 protrudes from the cover member 4 of the pump housing 2 into the pump chamber 23. The design of the lip 28 with a triangular profile is advantageous for its function as a stripping edge. Preferably, the lip 28 with a triangular profile is not designed as a sharp edge, but rather the vertices of the triangular profile are designed to have a finite and non-zero width in the radial direction.
[0086] The lip 28 has an outer diameter D2, which refers to the outer diameter D2 of the lip 28 at its axial end facing the rotor 10. Figure 4 In the first embodiment shown, the outer diameter D2 of the lip 28 is smaller than the diameter D1 of the central inlet region 25 of the rotor 10. Therefore, if the rotor 10 is displaced upward in the axial direction A according to the embodiment shown, the lip 28 can be inserted into the central inlet region 25.
[0087] As in Figure 4 As can be appreciated, the lip 28 is preferably designed to widen in the flow direction. In particular, in the first embodiment, the lip 28 is designed to widen tapered, such that the interior space of the lip 28 is designed in the shape of a truncated cone.
[0088] exist Figures 5 to 8 The designation represents various variations of the first embodiment of pump unit 1, wherein the designation corresponds to each case. Figure 4 The representation in [the text]. Therefore, Figures 5 to 8 Each is a cross-sectional view, wherein the cross-section is drawn along the axial direction A.
[0089] exist Figure 5 In the variant shown, the lip 28 has a smaller depth T, that is, the lip 28 protrudes less into the pump chamber 23 relative to the axial direction A. Furthermore, the outer diameter D2 of the lip 28 at its axial end facing the rotor 10 is greater than the diameter D1 of the central inlet region 25 of the rotor 10. Therefore, the lip 28 cannot be recessed into the central inlet region 25.
[0090] exist Figure 6 In the variant shown, the lip 28 bends outward, so that when viewed in the flow direction, the lip 28 widens again, but has walls designed in a curved manner relative to the axial direction A.
[0091] exist Figure 7 In the variant shown, the lip 28 is designed as a cylindrical tube section, i.e., having a constant inner diameter in the axial direction A. Here, as... Figure 7As indicated, the lip 28 may be designed as a single piece with the cover component 4. In other embodiments, the lip 28 may also be designed as a separate component, for example, as a hollow cylindrical tube section attached to or at the inlet 21.
[0092] exist Figure 8 In the variant shown, the cover component 4 of the pump housing 2 is designed in an inclined manner, such that the cover component 4 surrounds the inlet 21 at an angle greater than 90° with the axial direction. Therefore, the area of the cover component 4 adjacent to the inlet 21 is no longer parallel to the bottom of the pump housing 2, but rises towards the inlet 21.
[0093] Figure 8A A variant is shown in which the end face 107 of the lip 28 facing the rotor 10 is designed to be very flat. This variant is particularly advantageous from a manufacturing point of view.
[0094] Figure 9 A second embodiment of the pump unit 1 according to the invention is shown in cross-sectional view, wherein the cross-section is made along the axial direction.
[0095] In the following discussion, only the differences from the first embodiment will be discussed. Identical or functionally equivalent components from the second embodiment are designated by the same reference numerals as those in the first embodiment. In particular, the reference numerals have the same meaning as those already explained in connection with the first embodiment. It is understood that all foregoing explanations of the first embodiment and its variations apply in the same or similar manner to the second embodiment.
[0096] The second embodiment differs from the first embodiment in the design of the inlet surface 221 of the outlet 22, through which fluid flows out of the pump chamber and into the outlet 22.
[0097] Although in the first embodiment (see, for example, see...) Figure 4 In the present invention, the profile of the inlet surface 221 of the outlet 22 is designed as a circular surface, but the second embodiment of the pump unit 1 according to the present invention has an inlet surface 221 of the outlet 22 that is different from a circular surface.
[0098] Exit 22 further has a departure surface 222 (see also) Figure 2 The fluid exits through the exit surface 222 and then through the outlet 22. (e.g.) Figure 9 As indicated, the exit surface 222 of the outlet 22 has a circular profile, specifically a circular surface with a larger cross-sectional area than the entry surface. Therefore, the outlet 22 is designed to widen when viewed in the flow direction and change its cross-sectional area from the non-circular entry surface 221 to the circular exit surface.
[0099] exist Figure 9In the embodiment shown, the inlet surface 221 of the outlet is designed to have several straight edges 225. Here, the inlet surface 221 is designed substantially rectangularly, and particularly substantially squarely. Furthermore, if the profile of the inlet surface 221 is designed to have rounded corners, such as... Figure 9 As indicated in the text, it is preferred. Designing the entry surface 221 to have a non-circular profile (e.g., having several edges 225) has the following advantages: the cross-sectional area of the entry surface 221 can be made larger than that of an entry surface 221 with a circular profile without having to extend in the axial direction A, or the entry surface 221 of the outlet 22 can be arranged closer to the guide vane 103 or have a greater overlap with the guide vane 103 relative to the axial direction A.
[0100] In the following text, the maximum extension of the profile entering surface 221 in the axial direction A is called the profile height H1, and the maximum extension perpendicular to it in the radial direction is called the profile width B1.
[0101] Furthermore, such an embodiment of the profile of the entry surface 221 of the outlet 22 is also preferred, wherein the profile height H1 is less than the profile width B1. For example, the profile of the entry surface can be designed in a rectangular manner, wherein the profile width B1 is greater than the profile height H1. Due to this design, the center of the profile slides deeper compared to a circular profile of the same surface. In such an embodiment, the profile then has exactly four straight edges 225, wherein the edge 225 extending in the radial direction is longer than the edge 225 extending in the axial direction A. The corner connecting two adjacent straight edges 225 can be aligned with... Figure 9 The square outline entering surface 221 is rounded in a similar manner.
[0102] In the following text, based on Figure 10 and Figure 11 Explain two additional variations of the profile of the entry surface 221 for the exit 22, wherein the entry surface 221 has a profile different from that of a circular surface. In particular, it is possible for the profile to be more rounded or even designed to have no straight edges at all.
[0103] exist Figure 10 In the diagram, a first variant of the profile for entering surface 221 is indicated. The profile is identified using reference numeral P. In this first variant, the profile height H1 is the same as the profile width B1. For example, with... Figure 9 Compared to the basically square design of the outline shown in the figure, according to Figure 10 The outline P is designed to be quite rounded.
[0104] For comparison, in Figure 10The diagram also shows a circular surface K, whose diameter is the same as the contour height H1 and contour width B1. It is clear that the cross-sectional area of the contour P is larger than the surface area of the circle K.
[0105] Because of the deviated circular profile P of the inlet surface 221, it is possible to design the profile P of the inlet surface 221 of the outlet 22 to have a circular design with a larger profile (see, for example, see...). Figure 4 A larger cross-sectional area is achieved in the pump unit 200 without altering the geometry of the pump housing 2. The larger cross-sectional area of the profile P of the inlet surface 221 of the outlet 22 has the advantage of reducing the pressure drop across the outlet 22, which is substantially determined by this cross-sectional area, and is beneficial to the efficiency of the pump unit 1. Due to the reduced pressure drop across the outlet 22, the efficiency of the centrifugal pump 200 increases.
[0106] exist Figure 11 In the diagram, a second variant of the profile P entering surface 221 is indicated. Figure 11 In the second variant shown, the profile width B1 is greater than the profile height H1. Due to this design of profile P, compared to a circular profile with the same cross-sectional area, the center Z of profile P (or, more generally, the centroid of profile P in the case of an asymmetrical profile) is shifted downward relative to the axial direction A. In this design, where the profile width B1 is greater than the profile height H1, the center Z or centroid of profile P is closer to the plane that divides the trailing edge 108 of guide vane 103 into two segments of equal height in the axial direction A.
[0107] Various designs for profile P are possible, where the profile width B1 is greater than the profile height H1. For example, Figure 11 The diagram illustrates a design as a strongly rounded rectangle. The rounding of the rectangle can be so strong that the profile no longer includes any straight edges in the strict sense. Furthermore, it is possible to design the profile in an elliptical manner. Typically, such a design is preferred in a second variant, where at least a second direction B exists, in which the profile P has a maximum extension greater than the profile height H1 (i.e., the maximum extension of the profile in the axial direction A), wherein the second direction B and the axial direction A enclose an angle β that is not zero. Figure 11 In the representation, by way of example, the second direction B includes an angle β = 45° with respect to the axial direction A.
[0108] Furthermore, the present invention proposes a centrifugal pump 200 for conveying fluids, having a pump unit 1, wherein the pump unit 1 is designed according to the present invention. In a schematic cross-sectional view, Figure 12An embodiment of a centrifugal pump 200 according to the present invention is shown. 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, wherein a cup-shaped recess is provided at the first axial end 110. Figure 12 (Not shown in the image), the cylindrical cup-shaped portion 31 of the pump unit 1 can be inserted into the cup-shaped recess. The stator 100 together with the rotor 10 forms an electromagnetic rotary actuator for rotating the rotor 10 about the axial direction A, wherein the stator 100 is designed as a bearing and actuator stator, by means of which the rotor 10 can be magnetically driven without contact and can be magnetically levitated without contact relative to the stator 100, wherein the rotor 10 is passively magnetically stable relative to the axial direction A and actively magnetically levitated in a radial plane E perpendicular to the axial direction A.
[0109] Stator 100 includes a stator housing, which, for better overview, is... Figure 12 This is not explicitly stated. However, for example, it can be used in conjunction with... Figure 1 The stator 100 is designed in a similar manner to the stator 100' with stator housing 130' shown in the figure, wherein a recess 121' is provided in the stator housing 130', and the cylindrical cup-shaped portion 31 of the bottom part 3 of the pump housing 1 is inserted into the recess 121'.
[0110] Particularly preferably, the electromagnetic rotary actuator having a rotor 10 and a stator 100 is designed as a temple-shaped motor, wherein the stator 100 has a plurality of coil cores 125, each of the plurality of coil cores 125 including a longitudinal leg 126 and a transverse leg 127, the longitudinal leg 126 extending from a first end to a second end in the axial direction A, and 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 radially inward from the longitudinal leg 126 toward the rotor 10.
[0111] All the first ends (i.e., according to the lower end) of the longitudinal support leg 126 are connected to each other via the back iron 122 for conducting magnetic flux.
[0112] The coil core 125 is arranged around the rotor 10 in a circumferential direction, such that the rotor 10 is arranged between the transverse legs 127 of the coil core 125. At least one concentrated winding 160 is provided at each longitudinal leg 126, the winding surrounding the corresponding longitudinal leg 126.
[0113] The electromagnetic fields required for the magnetic drive and magnetic levitation of rotor 10 are generated using concentrated windings 160. These concentrated windings 160 thus generate the electromagnetic fields in the operating state, and these electromagnetic rotating fields generate torque on rotor 10 in a known manner. Furthermore, these electromagnetic rotating fields allow for the application of arbitrarily adjustable lateral forces on rotor 10 in the radial direction, enabling active control or adjustment of the radial position of rotor 10, i.e., its position in the radial plane E perpendicular to the axial direction A. Regarding the other three degrees of freedom—its position in the axial direction A and its tilt relative to the radial plane E perpendicular to the desired axis of rotation (two degrees of freedom)—rotor 10 is passively magnetically levitated or stabilized by magnetic reluctance; that is, it cannot be controlled.
Claims
1. A pump unit for a centrifugal pump, the centrifugal pump comprising the pump unit and a stator (100) extending in an axial direction (A) from a first axial end (110) to a second axial end (120), wherein, A cup-shaped recess is provided at the first axial end (110), into which the pump unit (1) can be inserted. The pump unit (1) has a pump housing (2) and a rotor (10) arranged within the pump housing (2). The pump housing (2) has an inlet (21) and an outlet (22) for the fluid to be conveyed. The rotor (10) has a plurality of guide vanes (103) for conveying the fluid, each guide vane (103) extending in the axial direction to the inlet-facing end face (107) of the rotor (10). The pump housing (2) defines a pump chamber (23). The rotor (10) is rotatable about the axial direction (A). The pump unit (1) is designed to rotate the rotor by means of the stator (100). The non-contact magnetic levitation of the rotor (10) and the non-contact magnetic drive of the rotor (10) are characterized in that the pump housing (2) has a cover part (4) and a bottom part (3), wherein the bottom part (3) has a cylindrical cup-shaped portion (31) for receiving the rotor (10), the cup-shaped portion (31) being insertable into the cup-shaped recess of the stator (100), characterized in that the inlet (21) has a lip (28) forming an axial end of the inlet (21), wherein the lip (28) protrudes into the pump chamber (23), and when viewed in the flow direction, when the rotor (10) is centered relative to the axial direction (A) in the operating state, the lip (28) terminates in front of the end face (107) of the rotor (10).
2. The pump unit according to claim 1, wherein, The guide vanes (103) of the rotor (10) are arranged around the central inlet region (25), which extends in the axial direction (A) to the end face (107) of the rotor (10) and has a diameter (D1).
3. The pump unit according to claim 2, wherein, The rotor (10) has at least one vent opening (104) that extends through the rotor (10) in the axial direction (A) from the central inlet region (25).
4. The pump unit according to any one of claims 2 to 3, wherein, The lip (28) of the entrance (21) has an outer diameter (D2) that is larger than the diameter (D1) of the central entrance region (25).
5. The pump unit according to any one of the preceding claims, wherein, The lip (28) has a substantially triangular profile, the apex of which faces the end face (107) of the rotor (10).
6. The pump unit according to any one of the preceding claims, wherein, When viewed in the flow direction, the lip (28) widens.
7. The pump unit according to any one of the preceding claims, wherein, The lip edge (28) is designed to curve outward.
8. The pump unit according to any one of claims 1 to 5, wherein, The lip (28) is designed as a cylindrical tube section.
9. The pump unit according to any one of the preceding claims, wherein, The cover component (4) of the pump housing (2) is designed in an inclined manner such that the cover component (4) at the inlet (21) surrounds the axial direction (A) at an angle (α) greater than 90°.
10. The pump unit according to any one of the preceding claims, wherein, The outlet (22) has an inlet surface (221) through which fluid flows from the pump chamber (23) into the outlet (22), wherein the inlet surface (221) of the outlet (22) has a profile different from that of a circular surface.
11. The pump unit according to claim 10, wherein, The profile (P) of the entry surface (221) is designed in a rectangular manner.
12. The pump unit according to any one of claims 10 to 11, wherein, The profile (P) of the entry surface (221) is designed to have rounded corners.
13. The pump unit according to any one of claims 10 to 12, wherein, The profile (P) of the entry surface (221) has a profile height (H1) in the axial direction (A) and a profile width (B1) in the radial direction perpendicular to the axial direction (A), wherein the profile width (B1) is greater than the profile height (H1).
14. A centrifugal pump for conveying fluid, comprising a pump unit designed according to any one of the preceding claims, and a stator (100) extending in the axial direction (A) from a first axial end (110) to a second axial end (120), wherein, A cup-shaped recess is provided at the first axial end (110), into which the cylindrical cup-shaped portion (31) of the pump unit (1) can be inserted. The stator (100) and the rotor (10) together form an electromagnetic rotary actuator for rotating the rotor (10) about the axial direction (A). The stator (100) is designed as a bearing and actuator stator. With the bearing and actuator stator, the rotor (10) can be magnetically driven without contact and can be magnetically levitated without contact relative to the stator (100). The rotor (10) is passively magnetically stable relative to the axial direction (A) and actively magnetically levitated in a radial plane (E) perpendicular to the axial direction (A).
15. The centrifugal pump according to claim 14, wherein, The electromagnetic rotary actuator is designed as a temple-shaped motor, wherein the stator (100) has a plurality of coil cores (125), each of the plurality of coil cores (125) including a longitudinal leg (126) and a transverse leg (127), the longitudinal leg (126) extending from a first end in the axial direction (A) to a second end, the transverse leg (127) being arranged at the second end of the longitudinal leg (126) and in the radial plane, and the transverse leg (127) extending from the longitudinal leg (126) in the radial direction, wherein the coil cores (125) are arranged relative to the circumferential direction around the rotor (10), such that the rotor (10) is arranged between the transverse legs (127) of the coil cores (125), and wherein at least one concentrated winding (160) is provided at each longitudinal leg (126), the winding surrounding the corresponding longitudinal leg (126).
Citation Information
Patent Citations
Rotary drive device and pump
WO2022004144A1