Centrifugal pump assembly

Abstract

The centrifugal pump assembly comprises: a pump head; a pump base; at least one fluid outlet passage; at least two rotor shaft segments coaxially aligned and extending along a rotor axis, each rotor shaft segment comprising a first axial end facing away from the pump head and a second axial end facing away from the pump base; one or more impellers, each impeller being fixed to or structurally integral with one rotor shaft segment, the first axial end of one rotor shaft segment comprising a positive fit coupling to the second axial end of another rotor shaft segment for torque transfer between the at least two rotor shaft segments; one or more pump stage housing segments arranged between the pump base and the pump head, each pump stage housing segment having a structure defining a guide passage for receiving pumped fluid from an impeller outlet of one impeller and for guiding the pumped fluid to an impeller inlet of another impeller or to the pump head, wherein the one or more pump stage housing segments each have a structure defining at least a portion of a wall segment of the at least one fluid outlet passage.

Description

Technical Field

[0001] The present disclosure relates to centrifugal pumps, and in particular to vertical multi-stage centrifugal pumps. Background Art

[0002] The shape and size of the pump components are designed to meet specific technical requirements and specifications. In particular, multi-stage centrifugal pumps like the Grundfos CR series pumps are available in a wide range of sizes to cover a wide power range. The greater the required pumping power, the larger the pump is usually designed.

[0003] Typically, such pumps include a rotor axis that can extend vertically or horizontally. An electric motor drives the rotor shaft that extends along the rotor axis into a pump housing that encloses at least one impeller stage. The pump base typically provides brackets and / or mounting brackets for securing the pump to a floor or wall. The inlet and outlet flanges for mounting the pump to the piping system can be part of the pump base and / or the pump housing. The pump housing is arranged between the motor and the pump base. The more pumping power or head required, the more impeller stages that can be stacked along the rotor axis within the pump housing. Therefore, the axial length of the pump housing is typically proportional to the number of impeller stages. Depending on the maximum flow rate that the pump should be able to deliver, the radial extension of the impeller and pump housing can be larger or smaller.

[0004] Patent documents EP3181908A1 and EP3670919A1 describe strap solutions for fixing the motor mount to the pump base, so that the pump housing is firmly clamped between the motor mount and the pump base due to the clamping tension transmitted by the strap or tie rods. Summary of the Invention

[0005] Compared to known centrifugal pumps of similar size, the centrifugal pump assembly according to the present disclosure has a significantly reduced number of components. Manufacturing and assembling these components is also simpler for the centrifugal pump assembly disclosed herein. Furthermore, maintenance, repair, and overhaul are less complex. Finally, the risk of pump bearing failure is reduced.

[0006] According to the present disclosure, a centrifugal pump assembly is provided, comprising

[0007] - a pump head, adapted to be connected to the motor base and / or the motor housing, or to be integral therewith,

[0008] - a pump base defining a pump inlet and a pump outlet,

[0009] - at least one fluid outlet channel for guiding the pumped fluid from the pump head to the pump outlet,

[0010] at least two rotor shaft segments, coaxially aligned and extending along the rotor axis, wherein each of the rotor shaft segments comprises a first axial end facing away from the pump head and a second axial end facing away from the pump base,

[0011] - one or more impellers having a structure defining at least one impeller fluid passage extending from an impeller inlet to an impeller outlet, wherein each of the one or more impellers is fixed to or structurally integral with one of the rotor shaft segments, wherein a first axial end of the one rotor shaft segment comprises a positive fit coupling to a second axial end of another of the rotor shaft segments for torque transmission between the at least two rotor shaft segments, and

[0012] one or more pump stage casing segments arranged between the pump base and the pump head, wherein each of the pump stage casing segments has a structure defining a guide passage for receiving the pumped fluid from the impeller outlet of one of the one or more impellers and for guiding the pumped fluid to the impeller inlet of another of the impellers or to the pump head,

[0013] Therein, the one or more pump stage housing segments each have a structure that defines at least a portion of a wall segment of the at least one fluid outlet channel.

[0014] Thus, the basic design and installation of the centrifugal pump assembly disclosed herein differs significantly from previously known pump designs. Firstly, the centrifugal pump assembly does not include a rotor shaft extending from the motor to the pump base as a single component. There is also no need for structures such as belts or tie rods to directly connect the pump head to the pump base for clamping the pump housing axially between the pump head and the pump base. Instead, according to the present disclosure, the rotor shaft and the pump housing are segmented in a modular manner, with each pump stage, i.e., impeller, having one pump stage housing segment. There are no length-dependent components, which is beneficial in terms of production costs, logistics, and service, i.e., the pump length can be defined by the number of modules rather than by various components of appropriate lengths. Assuming that the centrifugal pump assembly includes In the embodiment of the present invention, the present invention relates to a centrifugal pump assembly comprising a plurality of pump stages (i.e., impellers), wherein the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. In the embodiment of the present invention, the plurality of pump stages (i.e., impellers) are connected to each other by a plurality of rotor shaft segments. It should be noted that each impeller may be part of a rotor shaft segment and vice versa, regardless of whether the impeller is fixed to the respective rotor shaft segment or structurally integral therewith.

[0015] Optionally, the positive-fit connection between the rotor shaft segments is axially releasable. This means that the rotor shaft segments are not axially secured to one another, allowing them to move axially relative to one another within a certain range. This facilitates assembly and allows each pump stage to have a separate bearing, reducing wear and the risk of bearing failure. As will be explained later, an axial buffer chamber can be arranged between the rotor shaft segments and at least partially filled with a buffering medium and / or a spring element to dampen axial movement of the rotor shaft segments relative to one another.

[0016] Optionally, at least one of the one or more impellers is received within the pump base, wherein the one impeller is rotatably arranged within the pump base. The one impeller may be designated a first-stage impeller, which is located closest to the pump base and furthest from the pump head. In a vertical installation of the centrifugal pump assembly (where the pump base is the bottom-most component), the first-stage impeller is the bottom-most impeller. By receiving the impeller, the pump base partially functions as a pump housing.

[0017] Alternatively, each of the impeller and / or rotor shaft segments may define at least one rotating axial bearing surface facing the pump base and arranged in sliding contact with a corresponding static axial bearing surface defined by one of the one or more pump stage casing segments or the pump base and facing the pump head. This has the effect that the rotor shaft segments do not actually transmit axial forces to each other via a positive fit connection. Since each stage comprises its own axial bearing, the axial forces do not add up to a total high axial force acting on a single axial pump bearing for the entire pump as is known in the prior art. Consequently, single axial pump bearings, which are typically known to be subject to wear and bearing failure, the risk of which is reduced by the segmentation of the present invention.

[0018] Optionally, each of the impeller and / or rotor shaft segments can define at least one rotating radial bearing surface, which faces radially outward and is arranged to slide in contact with a corresponding static radial bearing surface, which is defined radially inward by one of the pump stage housing segments or the pump base. Similar to the axial bearing of each pump stage, the radial bearing of each pump stage further reduces wear and the risk of bearing failure. Alternatively, the bearing surface can be part of a dedicated sleeve assembly fixed to the impeller and / or rotor shaft segment.

[0019] Optionally, a group includes:

[0020] - at least one of the pump stage casing segments,

[0021] - at least one of the impellers,

[0022] - pump head, and

[0023] - A pump base; at least one of the components can have a single, monolithic, additively manufactured structure. Additive manufacturing, also known as 3D printing, particularly selective laser melting or laser powder bed fusion (LPBF) of one or more metal powders, or any other suitable additive manufacturing technique, allows for the design and fabrication of metallic, monolithic structures that are not feasible with conventional other manufacturing techniques. In particular, if the monolithic structure is additively manufactured, the design of internal fluid passages through the monolithic structure is less constrained by manufacturing limitations. For example, a pump stage casing segment, which defines, on the one hand, a channel for receiving the pumped fluid from one impeller and directing it to the next impeller, and, on the other hand, defines at least a portion of a wall segment of the at least one fluid outlet channel, can be hydrodynamically optimized in shape for most efficient fluid guidance. Furthermore, impeller designs with a hydrodynamically optimized shape and arrangement of internal impeller fluid passages can benefit from additive manufacturing to avoid conventional manufacturability compromising fluid dynamic performance. Furthermore, the pump head and / or pump base can preferably be additively manufactured as a monolithic structure. Additively manufactured components are particularly useful for minimizing the number of pump components. For example, a conventional vertical Grundfos CR pump may include more than 100 individual parts and assemblies, while a similarly sized centrifugal pump assembly disclosed herein may include fewer than 20 individual components.Another advantage of additively manufactured parts and assemblies may be reduced weight and material consumption.

[0024] Optionally, the one or more pump stage housing segments can each comprise a wall segment defining the at least one fluid outlet channel, wherein the wall segment completely surrounds the fluid pumped through the at least one fluid outlet channel. This means that no additional sleeve or the like is required to create a closed fluid outlet channel through which the pumped fluid returns from the pump head to the pump outlet. The pump stage housing segments can be sealed to one another, so that no fluid leaks outside the connection between the pump stage housing segments.

[0025] Optionally, the centrifugal pump assembly may further include a fluid outlet channel sleeve circumferentially surrounding the one or more pump stage housing segments, wherein the one or more pump stage housing segments each have a structure that defines a portion of a wall segment of the at least one fluid outlet channel, wherein the portion of the wall segment and the fluid outlet channel sleeve complement each other to define the at least one fluid outlet channel. The fluid outlet channel sleeve may be particularly advantageous in the case of multiple pump stages, because the more connections there are between the pump stage housing segments, the more sealing elements are required and the higher the risk of leakage. Therefore, the fluid outlet channel sleeve can reduce the number of required sealing elements, thereby reducing the risk of leakage. The fluid outlet channel sleeve may include a first axial end that is sealingly connected to the pump head and a second axial end that is sealingly connected to the pump base. It should be noted that the fluid outlet channel sleeve may not have any axial force transmission or structural function for holding the pump head and the pump base together. Therefore, the fluid outlet channel sleeve is preferably not used as a band or tie rod.

[0026] Alternatively, the one or more pump stage housing segments may each include a first mechanical coupling at a first axial segment end facing away from the pump head and a second mechanical coupling at a second axial segment end facing away from the pump base, wherein the one or more pump stage housing segments are coupled to the pump base or another pump stage housing segment via the first mechanical coupling, and wherein the one or more pump stage housing segments are coupled to the pump head or another pump stage housing segment via the second mechanical coupling. This facilitates modular segmented installation of the pump housing, as the one or more pump stage housing segments can be assembled together in any order. The first and second mechanical couplings may serve to hold the pump assembly axially together.

[0027] Optionally, the first mechanical coupling is formed as a corresponding coupling counterpart of the second mechanical coupling, so as to be releasably coupled to a second coupling of another pump stage housing segment. This facilitates the installation of modular segments of the pump housing and provides easy access to the assembly for maintenance, repair, and overhaul. It is also very easy to replace individual pump stage housing segments, if necessary.

[0028] Optionally, the first mechanical coupling and / or the second mechanical coupling of the one or more pump stage housing segments predefine one or more different rotational mounting positions of the one or more pump stage housing segments. This is particularly useful if there are more than one fluid outlet channel defined in parallel by the pump stage housing segments and in order to ensure that each fluid outlet channel is well defined in the one or more different rotational mounting positions.

[0029] Alternatively, the first and second mechanical couplings may define corresponding coupling partners of a bayonet coupling. The bayonet coupling has the advantage that it defines different rotational mounting positions and may not require tools for assembly. Furthermore, the bayonet coupling may provide a well-defined sealing pressure between connected pump stage housing segments and / or between a pump stage housing segment and the pump head / base.

[0030] Optionally, the centrifugal pump assembly may further include at least one sealing element for sealing the at least one fluid outlet channel. For example, a sealing ring, such as an O-ring, may be used to seal the connection between pump stage housing segments and / or between a pump stage housing segment and the pump head / base. Preferably, the at least one sealing element is positioned radially outward from the at least one fluid outlet channel to prevent leakage to the outside.

[0031] Optionally, the pump head may define a return flow passage for receiving pumped fluid from one of the one or more impellers and redirecting the pumped fluid to the at least one fluid outlet passage section of one of the pump stage housing sections coupled to the pump head. Assuming the centrifugal pump assembly includes pump stage (i.e., impeller), the return flow channel starts from the nth (n th ) impeller outlet receives the pumped fluid, that is, the last or topmost impeller in the vertical stack of n impellers. The return channel redirects the pumped fluid to the impeller outlet of the n-1th ((n-1) th ) portion of the fluid outlet passage defined by the pumping stage casing segments, i.e., redirected to the last or topmost pumping stage casing segment of the vertical stack of n-1 pumping stage casing segments.

[0032] Optionally, the pump head may define a guide passage for receiving the pumped fluid from the impeller outlet of the last impeller and for guiding the pumped fluid to the fluid outlet channel. Thus, the guide passage may be a portion of the return flow channel that contributes to the pumping efficiency of the last impeller. The guide passage of the pump head may be shaped the same as or similar to the guide passage of the pump stage casing segment(s).

[0033] Alternatively, the pump head may be connected to or integral with the motor housing, and a return channel may extend through the motor housing in thermal contact with the heat generating components of the motor, such that the pumped fluid cools the heat generating components of the motor. This is particularly useful for reducing the number of parts and components and improving pump performance and durability. In particular, the additively manufactured pump head integral with the motor housing may be designed to include one or more cooling channels in thermal contact with the heat generating components of the motor. Obviously, the pumped fluid is only effective as a radiator if the pumped fluid is sufficiently cold, such as cold water.

[0034] Optionally, particularly in conjunction with axially releasable positive-fit couplings between the rotor shaft segments, an axial buffer chamber can be provided between a first axial end of the rotor shaft segment of the impeller or impellers and a second axial end of another rotor shaft segment coupled thereto, for torque transmission between the coupled rotor shaft segments. In conjunction with axial bearings for each pump stage, such axial buffer chambers can further facilitate the transmission of little or no axial force from one rotor shaft segment to the next. This reduces the risk of wear and bearing failure.

[0035] Optionally, the axial buffer chamber can be at least partially filled with a buffer medium. The buffer medium can be compressible, such as air, a gas, a flexible material such as an elastomer, or a combination thereof. Alternatively or additionally, the buffer medium can include a liquid, such as a pumped fluid, wherein the liquid is forced to escape through one or more narrow paths under axial pressure on the axial buffer chamber. The buffer medium dampens undesirable axial movement of the rotor shaft segments relative to each other and can prevent noise generated by axial impact between the rotor shaft segments.

[0036] Optionally, the pump base may define a fluid intake passage extending from the pump inlet to a suction aperture, wherein the suction aperture is arranged coaxially with the rotor axis and laterally surrounds a rotor shaft segment of one of the one or more impellers. The rotor shaft section preferably extends axially from the impeller into the suction opening of the pump base.

[0037] Optionally, the pump base may define a tubular element coaxially arranged within the suction bore for receiving the rotor shaft segment of the impeller, wherein the tubular element provides at least one static radial bearing surface in sliding contact with the rotor shaft segment of the impeller. Preferably, the impeller inlet extends annularly around the rotor shaft segment, and the tubular element is positioned radially between the impeller inlet and the rotor shaft segment. The at least one static radial bearing surface is preferably an inner surface of the tubular element, and the outer surface of the tubular element is preferably surrounded by the fluid drawn into the suction bore. The tubular element may be supported within the suction bore by radially extending webs. The tubular element and the webs may preferably be an integral component of the pump base, preferably as part of an integral additively manufactured structure. Since the webs extend across the fluid flow path through the suction bore, they can be shaped in such a way that they cause as little fluid dynamic resistance and turbulence as possible.

[0038] Alternatively, the centrifugal pump may lack a shaft extending from the motor base to the pump base, and / or tie rods or straps for holding the pump head and pump base together.

[0039] Alternatively, the impeller outlet may face away from the pump base, and the inlet of the guide passage may face the pump base, wherein the inlet of the guide passage is arranged to receive the pumped fluid from the impeller outlet. Preferably, the fluid enters the impeller inlet in an axial direction toward the pump head and leaves the impeller outlet in an axial direction toward the pump head, wherein the impeller outlet is arranged radially outward from the impeller inlet and has a greater axial distance from the pump base than the impeller inlet. Therefore, the pumped fluid preferably follows a fluid-dynamically optimized flow path in the axial direction within the impeller, such as a smooth S-shape. Preferably, the guide passage within the pump stage housing segment may define a corresponding fluid-dynamically optimized flow path in the radially inward direction, such as an inverted smooth S-shape, from the radially outward inlet of the guide passage to the radially inward outlet of the guide passage, which flow path supplies the impeller inlet of the subsequent impeller. Therefore, the pumped fluid enters and leaves the impeller substantially in the axial direction. This is fluid-dynamically beneficial, but requires a more complex fluid channel design. Therefore, the impeller(s) and / or the pump stage casing segment(s) are preferably additively manufactured as a one-piece structure with internal fluid channels.

[0040] Optionally, all impellers and / or pump stage casing segments can be identical in shape, size, and material. This reduces component diversity and simplifies assembly and spare parts management. Within certain limits, it also allows the size of the pump assembly to be quickly and easily adapted by adding or removing pump stages, thereby reducing the number of pump models offered by the pump manufacturer.

[0041] The segmented, modular design of the centrifugal pump assembly disclosed herein allows for a higher degree of variability and customization for specific applications and customer needs. Fewer components and assemblies also require fewer spare parts. Furthermore, additively manufactured spare parts do not need to be maintained in inventory but can be produced on demand. If replacing only a defective pump stage is sufficient, there is no need to replace the entire centrifugal pump assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Embodiments of the present disclosure will now be described by way of example with reference to the following drawings, in which:

[0043] Figure 1 shows an exploded view of an embodiment of a centrifugal pump assembly according to the present disclosure;

[0044] Figure 2a 、 2b shows a mechanical coupling mechanism between pump stage casing segments of an embodiment of a centrifugal pump assembly according to the present disclosure;

[0045] Figure 3 shows a longitudinal cross-sectional view of three rotor shaft segments in an embodiment of a centrifugal pump assembly according to the present disclosure;

[0046] Figure 4a 、4b Two different perspective views of an impeller (including rotor shaft segments) of an embodiment of a centrifugal pump assembly according to the present disclosure are shown;

[0047] Figure 5 shows a partial longitudinal cross-sectional view of a pump stage of an embodiment of a centrifugal pump assembly according to the present disclosure;

[0048] Figure 6 shows a longitudinal cross-sectional view of a pump base according to an embodiment of a centrifugal pump assembly of the present disclosure;

[0049] Figure 7 a partial longitudinal cross-sectional view showing two pump stages of an alternative embodiment of a centrifugal pump assembly according to the present disclosure; and

[0050] Figure 8 A longitudinal cross-sectional view of an embodiment of a centrifugal pump assembly according to the present disclosure is shown.

[0051] Reference Signs List

[0052] 1 Centrifugal pump assembly

[0053] 3a-c Impeller

[0054] 5 Pump base

[0055] 7a, b Pump stage housing elements

[0056] 9a-c Sealing element

[0057] 11 Pump head

[0058] 13 Pump inlet

[0059] 15 Pump outlet

[0060] 17 legs

[0061] 18 Opening

[0062] 19 Impeller inlet

[0063] 21 Impeller outlet

[0064] 23 blades

[0065] 25a-d rotor shaft section

[0066] 27 First mechanical connection

[0067] 29 End of the first axial segment

[0068] 31 Second mechanical connection

[0069] 33 End of the second axial segment

[0070] 35 Pump head end

[0071] 37 Pump base end

[0072] 39 Impeller support

[0073] 41 Tubular components

[0074] 42 belly plate

[0075] 43 Static internal radial bearing surface

[0076] 45 Rotating external radial bearing surface

[0077] 46 Static axial bearing surface

[0078] 47 Guidance Path

[0079] 48 Rotating axial bearing surface

[0080] 51 Suction hole

[0081] 53 fluid outlet channel

[0082] 55 First axial end of the rotor shaft segment

[0083] 57 Second axial end of the rotor shaft segment

[0084] 59 Axial buffer chamber

[0085] 61 Fluid outlet channel sleeve

[0086] 63 Motor housing

[0087] 65 Pump head end

[0088] 67 rotor

[0089] 69 stator

[0090] 71 Reflux Channel

[0091] z rotor axis DETAILED DESCRIPTION

[0092] Figure 1 A centrifugal pump assembly 1 is shown in the form of a vertical multistage centrifugal pump assembly, comprising a vertical rotor axis z and n=3 pump stages, i.e., three impellers 3a-c. The centrifugal pump assembly 1 comprises a pump base 5, three impellers 3a-c, two pump stage housing segments 7a, b, three sealing elements 9a-c, and a pump head 11, i.e., a total of ten individual components (excluding components of the motor and motor control electronics). Compared to a conventional multistage centrifugal pump assembly comprising three pump stages, Figure 1 The number of components of the centrifugal pump assembly 1 shown in FIG is significantly reduced. In addition to the sealing elements 9a-c, Figure 1One, some or all of the other seven components shown in are preferably additively manufactured.

[0093] The pump base 5 is an integral additively manufactured structure preferably made of a metal material. The pump base 5 defines a pump inlet 13 and a pump outlet 15. The pump inlet 13 and the pump outlet 15 are coaxially arranged to face opposite horizontal directions so that the centrifugal pump assembly 1 can be installed into a straight pipe section. The pump base 5 also defines a support structure having a foot 17 standing on the floor or the ground. The foot 17 includes an opening 18 for fastening the pump base 5 to the ground with the aid of a fastener (e.g., a screw). The upper portion of the pump base 5 defines a receiving structure for receiving the first impeller 3a. The upper portion of the pump base 5 partially serves as a pump housing. In Figure 6 More details of the pump base 5 can be seen in FIG.

[0094] The impellers 3a-c each have a structure defining a plurality of impeller fluid passages extending from an impeller inlet 19 to an impeller outlet 21. The impeller inlet 19 faces the pump base 5, i.e. downward (at Figure 4b The impeller outlet 21 faces the pump head 11, i.e. upwards. The impeller outlet 21 is located radially further outwards than the impeller inlet 19. The impeller fluid channels within the impellers 3a-c are separated from each other by impeller blades 23 (at Figure 3 and Figure 4a ). In addition, the impellers 3a-c each form a rotor shaft section 25a-c as an integral structure, which extends mainly in the axial direction towards the pump base 5, i.e. downwards. The rotor shaft section 25a of the first impeller 3a (i.e. the bottommost impeller) extends into the suction opening 51 of the pump base 5 (at Figure 6 The rotor shaft segments 25b, c of the other impellers 3b, c extend into the respective pump stage casing segments 7a, b positioned axially below the respective impeller 3b, c (better visible in FIG. 1 ). Figure 3 (better visible in the).

[0095] The first pump stage housing segment 7a is arranged axially above the first impeller 3a, and the second pump stage housing segment 7b is arranged axially above the second impeller 3b. The two pump stage housing segments 7a, b are essentially identical in material and shape. Figure 2aAs shown in more detail in FIG, they each include a first mechanical coupling 27 at a first axial segment end 29 facing the pump base 5 and a second mechanical coupling 31 at a second axial segment end 33 facing away from the pump base 5. The pump head 11 includes the same first mechanical coupling 27 at a (lower) pump head end 35 facing the pump base 5. Similarly, the pump base 5 includes the same second mechanical coupling 31 at an (upper) pump base end 37 facing the pump head 11. The first mechanical coupling 27 is a male component of a bayonet coupling in the form of radially outward rivet-like protrusions. In the example shown, there are six radially outward rivet-like protrusions evenly distributed circumferentially. The second mechanical coupling 31 is a corresponding female component of the bayonet coupling, which is in the form of a hook-shaped recess at the radial inside for receiving the head of the rivet-like protrusion of the first mechanical coupling 27. The first mechanical coupling 27 and the second mechanical coupling 31 are locked to each other by pushing the rivet-like projection axially into the hook-shaped recess up to a mechanical stop and subsequently twisting it about the rotor axis z to move the rivet-like projection into a defined locking position.

[0096] In the locked position, the first sealing element 9a is sealingly squeezed between the pump base 5 and the (lower) first axial segment end 29 of the (bottommost) first pump stage housing segment 7a. Similarly, the second sealing element 9b is sealingly squeezed between the first pump stage housing segment 7a and the (lower) first axial segment end 29 of the (topmost) second pump stage housing segment 7b. Finally, the third sealing element 9c is sealingly squeezed between the second pump stage housing segment 7b and the (lower) pump head end 35. As a result, the fluid passages within the centrifugal pump assembly 1 are completely sealed to prevent leakage. Figure 2a As shown, the pump stage housing segment 7a comprises a sealing groove 30 at the (lower) first axial segment end 29, wherein the sealing elements 9a-c are at least partially positioned in the sealing groove 30. The pump head 11 also comprises a sealing groove 30 at the (lower) pump head end 35 (see Figure 1 Before the pump stage housing segments 7a, b are coupled to each other or to the pump head 11 or the pump base 5, the sealing elements 9a-c at least partially extend radially outwards out of the sealing groove 30. When the pump stage housing segments 7a, b are coupled to each other or to the pump head 11 or the pump base 5, the sealing elements 9a-c are pressed radially inwards by the radial inner surface 32 of the other pump stage housing segment 7a, b or the pump base 5 in a sealing manner (see Figure 5 ). Alternatively or additionally, the sealing elements 9a-c may be arranged to be axially compressed between the components.

[0097] Due to the six-fold rotational symmetry of the mechanical couplings 27, 31, there are six different rotational mounting positions that can be used as locking positions. Preferably, each of the pump stage housing segments 7a, b includes six-fold rotational symmetry, making the six different rotational mounting positions indistinguishable from one another. This facilitates the assembly process and reduces the risk of incorrect assembly. Those skilled in the art will readily appreciate that any m-fold rotational symmetry can be used to achieve this, where m ≥ 2.

[0098] Figure 2b The pump stage housing segments 7a, b are shown to include an impeller receptacle 39 that is open toward the (upper) second axial segment end 33. The impeller receptacle 39 is configured to fully receive one of the impellers 3b, c. The pump stage housing segments 7a, b include a centrally arranged tubular element 41 for receiving the rotor shaft segments 25a-c of the impellers 3b, c.

[0099] like Figure 2b As shown, each pump stage has its own axial and radial bearings. The tubular element 41 defines a static radially inner bearing surface 43. When the centrifugal pump assembly 1 is fully assembled, the static radially inner bearing surface 43 is in low friction sliding contact with the corresponding rotating radially outer bearing surface 45 of the rotor shaft segments 25a-c (see Figure 3 and Figure 4b ). Furthermore, the pump stage housing segments 7a, b define a static annular axial bearing surface 46 facing the pump head 11. When the centrifugal pump assembly 1 is fully assembled, the static axial bearing surface 46 is in low-friction sliding contact with a corresponding rotating axial bearing surface 48 of the impeller 3b, c pointing downwards, i.e. towards the pump base 5 (see Figure 3 and Figure 4b ).

[0100] When viewed from the (upper) pump base end 37, the pump base 5 appears substantially the same as Figure 2b The pump base 5 further includes an impeller holder 39 that is open toward the (upper) pump base end 37. The impeller holder 39 of the pump base 5 is configured to fully receive the first impeller 3a. The pump base 5 includes a pump housing 39 that is coaxially arranged at the suction hole 51 (see Figure 6 ) for receiving the rotor shaft section 25a of the first impeller 3a. The tubular element 41 is supported in the suction hole 51 by radially extending webs 42 (see Figure 3 、 6 and 7). The tubular element 41 of the pump base 5 defines a static radially inner bearing surface 43. When the centrifugal pump assembly 1 is fully assembled, the static radially inner bearing surface 43 is in low-friction sliding contact with a corresponding rotating radially outer bearing surface 45 of the rotor shaft segment 25a of the first impeller 3a (see Figure 3 、 4b and Figure 6). In addition, the pump base 5 defines a static annular axial bearing surface 46 facing the pump head 11. When the centrifugal pump assembly 1 is fully assembled, the static axial bearing surface 46 is in low-friction sliding contact with a corresponding downwardly directed, i.e., rotating axial bearing surface 48 of the first impeller 3a of the pump base 5 (see Figure 3 and Figure 4b The pump base 5 also presses the first sealing element 9a radially inwards into the sealing groove 30 of the first pump stage housing segment 7a.

[0101] It should be noted that "low-friction sliding contact" in this context should mean that a thin lubricating film of the pumped fluid can be placed between the bearing surfaces. The bearing surfaces can include different materials to reduce friction and wear. For example, the bearing surfaces can be coated, treated and / or machined. In the case where the pump stage casing segments 7a, b and / or the impellers 3a-c are additively manufactured, multi-material additive manufacturing (MMAM) with or without post-processing can be used to produce the bearing surfaces 43, 45, 46, 48 from a different material than the rest of the corresponding component to which they belong.

[0102] Radially between the tubular element 41 and the static axial bearing surface 46 there is an annular fluid outlet of a guide channel 47 defined by the internal structure of the pump stage housing segments 7a, b. The impellers 3a-c located in the impeller holder 39 comprise an impeller inlet 19 (see Figure 4b ), the impeller inlet receives the pumped fluid from the fluid outlet of the guide passage 47.

[0103] Radially outward from the impeller carrier 39, the pump stage housing segments 7a, b each have a structure that defines a section of a fluid outlet channel 53. The pumped fluid is guided downward from the pump head 11 through the fluid outlet channel 53 toward the pump outlet 15. Due to the selected six-fold rotationally symmetrical design of the pump stage housing segments 7a, b of the illustrated embodiment, there are six fluid outlet channels 53 distributed circumferentially around the impeller carrier 39. In the illustrated embodiment, the fluid outlet channels 53 are separated from one another before they are combined in the suction opening 51.

[0104] Figure 3 The rotor shaft segments 25a-d are shown when the centrifugal pump assembly 1 is fully assembled. The impellers 3a-c are arranged in their associated impeller sockets 39 so that the impeller inlet 19 receives the fluid directed substantially vertically upwards by the guide passage 47. The rotor shaft segments 25a-c extend through the tubular element 41. The rotor shaft segments 25a-d are coupled to each other by a positive fit in the form of a claw coupling (see Figure 4bThe positive-fit connection is axially loose but allows torque transmission. The (lower) first axial end 55 of the rotor shaft segments 25a-d includes a positive-fit connection that is connected to the (upper) second axial end 57 of another of the rotor shaft segments 25a-d for transmitting torque between the rotor shaft segments 25a-d. The connection portion at the (lower) first axial end 55 of the rotor shaft segment 25a of the first impeller 3a is unused. The connection portion at the (lower) first axial end 55 of the rotor shaft segment 25b of the second impeller 3b engages with the (upper) second axial end 57 of the rotor shaft segment 25a of the first impeller 3a. The connection portion at the (lower) first axial end 55 of the rotor shaft segment 25c of the third impeller 3c engages with the (upper) second axial end 57 of the rotor shaft segment 25b of the second impeller 3b. At least one of the rotor shaft segments 25a-d is not an integral part of one of the impellers 3a-c. Here, this is the fourth rotor shaft segment 25d that extends toward the motor. The coupling portion at the (lower) first axial end 55 of the fourth rotor shaft segment 25d is engaged with the (upper) second axial end 57 of the rotor shaft segment 25c of the third impeller 3c. Thus, the torque of the motor is transmitted from the fourth rotor shaft segment 25d to the other rotor shaft segments 25a-c.

[0105] A small axial buffer chamber 59 is provided between a first axial end 55 of a rotor shaft segment 25a-d and a second axial end of the next rotor shaft segment 25a-c. The axial buffer chamber 59 is at least partially filled with a buffer medium (e.g., air, pumped fluid, elastomer, or a combination thereof).

[0106] Figure 4a 、 4b Impellers 3a-c are shown in greater detail. Impellers 3a-c have a structure defining an impeller fluid channel that spirals radially outward and upward in an S-shape from impeller inlet 19 to impeller outlet 21. Impeller inlet 19 faces the pump base 5, i.e., downward. Impeller outlet 21 faces the pump head 11, i.e., upward. The impeller fluid channels within impellers 3a-c are separated from one another by 16 impeller blades 23. When the centrifugal pump assembly 1 is fully assembled, the fluid inlet of the guide passage 47 within the pump stage housing segments 7a, b receives fluid flowing substantially vertically upward from the impeller outlet 21.

[0107] exist Figure 5, the flow of the pumped fluid is indicated by the large arrows. As shown, each pump stage casing segment 7a, b defines a guide passage 47 for receiving fluid pumped from the impeller outlet 21 and directing the pumped fluid radially inward along an S-shaped path toward the impeller inlet 19 of the subsequent impeller 3a-c. The impeller outlet 21 faces away from the pump base 5, and the inlet of the guide passage 47 faces the pump base 5. Similarly, the impeller inlet faces away from the pump head 11, and the outlet of the guide passage faces away from the pump base 5. Thus, the pumped fluid flows substantially axially (vertically) at the interface between the impeller 19 and the guide passage 47.

[0108] Each pump stage housing segment 7a, b also defines a section of the outlet fluid passage 53 through which the pumped fluid flows substantially downwardly towards the pump outlet 15. Figure 5 As shown, the outlet fluid channel 53 has a wavy shape, which can optimize fluid dynamic efficiency and / or structural integrity at the expense of minimal material and weight. Here, additive manufacturing of the pump stage housing segments 7a, b significantly increases design freedom. However, if more appropriate for any reason, the outlet fluid channel 53 can have a different shape, such as a straight vertical shape.

[0109] Figure 6 The pump base 5 is shown in greater detail. As already explained above, the pump base 5 partially serves as the pump housing for the first pump stage. Therefore, the pump base 5 includes an impeller receptacle 39 that is open toward the (upper) pump base end 37. The first impeller 3a is completely received within the impeller receptacle 39 of the pump base 5. In other words, the pump base 5 completely surrounds the first impeller 3a. A tubular element 41 of the pump base 5 is coaxially arranged within a suction opening 51 of the rotor shaft segment 25a for receiving the first impeller 3a. The tubular element 41 is supported within the suction opening 51 by radially extending webs 42. The tubular element 41 of the pump base 5 defines a static radially inner bearing surface 43. The static radially inner bearing surface 43 is in low-friction sliding contact with a corresponding rotating radially outer bearing surface 45 of the rotor shaft segment 25a of the first impeller 3a. Furthermore, the pump base 5 defines a static annular axial bearing surface 46 facing the pump head 11. The static axial bearing surface 46 is in low-friction sliding contact with a corresponding rotating axial bearing surface 48 of the first impeller 3a pointing downwards, ie towards the pump base 5 (see Figure 3 and Figure 4b ).

[0110] Figure 7An embodiment is shown in which the pump stage housing segments 7a, b have a structure that defines only a portion of the wall segment of the fluid outlet channel 53, so that the pumped fluid flows downwardly along the outer periphery of the pump stage housing segments 7a, b toward the pump outlet 15. The centrifugal pump assembly 1 further comprises a fluid outlet channel sleeve 61 circumferentially surrounding the pump stage housing segments 7a, b so as to define the remaining portion of the wall segment of the fluid outlet channel 53, so that the pumped fluid flows downwardly along the inner surface of the fluid outlet channel sleeve 61, i.e., radially between the pump stage housing segments 7a, b and the fluid outlet channel sleeve 61 toward the pump outlet 15. In other words, the portion of the wall segment defined by the pump stage housing segments 7a, b and the fluid outlet channel sleeve 61 complement each other to define the at least one fluid outlet channel 53. The remainder of this embodiment is the same as Figures 1 to 6 The same as the previously described embodiment.

[0111] Figure 7 The embodiment shown is particularly advantageous for centrifugal pump assemblies with many pump stages, since no sealing elements 9b are required between the pump stage housing segments 7a, b. A first sealing element 9a can be used to seal the gap between the fluid outlet channel sleeve 61 and the pump base 5. Similarly, a (topmost) third sealing element 9c can be used to seal the gap between the fluid outlet channel sleeve 61 and the pump head 11. Therefore, only two sealing elements 9a, c are required here, regardless of the number of pump stages. The more pump stages there are, the more sealing elements 9b can be saved, which reduces the number of components and the risk of seal leakage. It should be noted that the fluid outlet channel sleeve 61 does not pull the pump head 11 and the pump base 5 together. As Figures 1 to 6 As described in the exemplary embodiment of FIG. 5 , this is achieved by mechanically connecting the pump stage housing segments 7 a, b to one another and to the pump base 5 and the pump head 11 , respectively.

[0112] Figure 8 An embodiment of a three-stage vertical centrifugal pump assembly 1 is shown in full longitudinal section, which particularly shows an embodiment of a pump head 11. The pump head 11 may be structurally integral with the motor housing 63 or as Figure 8 The pump head 11 is connected to the motor housing as shown. The pump head 11 is connected with its (lower) pump head end 35 to the (topmost) pump stage housing segment 7b and with its opposite pump head end 65 to the motor housing 63. The motor housing 63 encloses an electric motor, preferably a permanent magnet synchronous motor (PMSM), comprising a rotor 67 fixed to the (topmost) rotor shaft segment 25d and a stator 69 surrounding the rotor 67.

[0113] The motor housing 63 defines a return channel 71 for receiving the pumped fluid from the last (topmost) impeller 3c and directing the pumped fluid to a section of the fluid outlet channel 53 defined by the (topmost) second pump stage housing segment 7b, which is connected to the pump head 11. The motor housing 63 acts as a heat sink in thermal contact with heat-generating electrical components of the motor or control electronics for controlling the motor. In order to cool the motor housing 63 to improve heat dissipation, the return channel 71 extends through the motor housing 63 in thermal contact with the heat-generating components of the motor so that the pumped fluid cools the heat-generating components of the motor. Preferably, one return channel 71 is provided for each fluid outlet channel 53, i.e., six return channels 71 are provided in the illustrated embodiment. Each return channel 71 can follow a U-shaped path within the motor housing 63, the U-shaped path extending substantially along the entire axial length of the stator 69, wherein the return channel 71 includes an upward section and a downward section. Figure 8 The longitudinal section of FIG shows only two downward sections of two of the return channels 71, since the upward section and the other four return channels 71 are outside the cutting plane. The downward sections of the return channels 71 supply the fluid outlet channel 53 to guide the pumped fluid downward toward the pump outlet 15.

[0114] Where, in the foregoing description, reference is made to integers or elements that have known, obvious, or foreseeable equivalents, such equivalents are incorporated herein as if individually described. Reference should be made to the claims for determining the true scope of the present disclosure, which should be interpreted as encompassing any such equivalents. The reader will also understand that integers or features described in this disclosure as optional, preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims.

[0115] The above embodiments should be understood as illustrative examples of the present disclosure. It should be understood that any feature described with respect to any embodiment can be used alone or in combination with the other features described, and can also be used in combination with one or more features of any other embodiment, or with any combination of any other embodiment. Although at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions, and alternatives are obvious to those of ordinary skill in the art and can be changed without departing from the scope of the subject matter described herein, and this application is intended to cover any modifications or variations of the specific embodiments discussed herein.

[0116] In addition, "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude the plural. In addition, a feature or step described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. The method steps may be applied in any order or in parallel, or may constitute part of or a more detailed version of another method step. It should be understood that all such modifications should be embodied within the scope of this patent, reasonably and appropriately falling within the scope of the contribution to the art. Such modifications, substitutions and alternatives may be made without departing from the spirit and scope of the present disclosure, which should be determined in accordance with the appended claims and their legal equivalents.

Claims

1. A centrifugal pump assembly (1), comprising - a pump head (11) for connection to the motor base and / or motor housing (63) or integral therewith, - a pump base (5), defining a pump inlet (13) and a pump outlet (15), - at least one fluid outlet channel (53) for guiding the pumped fluid from the pump head (11) to the pump outlet (15), - at least two rotor shaft segments (25a-d), coaxially aligned and extending along the rotor axis (z), wherein Each of the rotor shaft segments (25a-d) comprises a first axial end (55) facing away from the pump head (11) and a second axial end (57) facing away from the pump base (5), - one or more impellers (3a-c) having a structure defining at least one impeller fluid passage extending from an impeller inlet (19) to an impeller outlet (21), wherein each of the one or more impellers (3a-c) is fixed to or structurally integral with one of the rotor shaft segments (25a-d), wherein a first axial end (55) of the one rotor shaft segment includes a positive-fit coupling to a second axial end (57) of another of the rotor shaft segments (25a-d) for torque transmission between the at least two rotor shaft segments (25a-d), and - one or more pump stage housing segments (7a, b) arranged between the pump base (5) and the pump head (11), wherein each of the pump stage housing segments (7a, b) has a structure defining a guide passage (47) for receiving the pumped fluid from the impeller outlet (21) of one of the one or more impellers (3a-c) and for guiding the pumped fluid to the impeller inlet (19) of another of the impellers (3a-c) or to the pump head (11), wherein the one or more pump stage housing segments (7a, b) each have a structure defining at least a portion of a wall segment of the at least one fluid outlet channel (53), wherein the one or more pump stage housing segments (7a, b) respectively comprise a first mechanical coupling (27) at a first axial segment end (29) facing the pump base (5) and a second mechanical coupling (31) at a second axial segment end (33) facing the pump head (11), wherein the one or more pump stage housing segments (7a, b) are coupled to the pump base (5) or another pump stage housing segment (7a, b) by the first mechanical coupling (27), and wherein the one or more pump stage housing segments (7a, b) are coupled to the pump head (11) or another pump stage housing segment (7a, b) by the second mechanical coupling (31).

2. The centrifugal pump assembly (1) according to claim 1, wherein: At least one impeller (3a) of the one or more impellers (3a-c) is received in the pump base (5), wherein the one impeller (3a) is rotatably arranged in the pump base (5).

3. A centrifugal pump assembly (1) according to claim 1 or 2, wherein: Each of the impellers (3a-c) and / or rotor shaft segments (25a-d) defines at least one rotating axial bearing surface (48) facing the pump base (5) and arranged in sliding contact with a corresponding static axial bearing surface (46) defined by one of the one or more pump stage casing segments (7a, b) or the pump base (5) and facing the pump head (11).

4. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: The positive-fit couplings of the rotor shaft segments (25a-d) are axially releasable.

5. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: Each of the impellers (3a-c) and / or rotor shaft segments (25a-d) defines at least one rotating radial bearing surface (45) directed radially outwards and arranged in sliding contact with a corresponding static radial bearing surface (43) defined by one of the pump stage casing segments (7a, b) or the pump base (5) and directed radially inwards.

6. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: A group includes: - at least one of the pump stage housing segments (7a, b), - at least one of the impellers (3a-c), - the pump head (11), and - the pump base (5); At least one of the group has a single unitary additively manufactured structure.

7. A centrifugal pump assembly (1) according to claim 1 or 2, wherein: The one or more pump stage housing segments (7a, b) each have a structure of a wall segment defining the at least one fluid outlet channel (53), wherein the wall segment completely surrounds the fluid pumped through the at least one fluid outlet channel (53).

8. The centrifugal pump assembly (1) according to claim 1 or 2, further comprising a fluid outlet passage sleeve (61) circumferentially surrounding the one or more pump stage casing segments (7a, b), wherein The one or more pump stage housing segments (7a, b) each have a structure defining a portion of a wall segment of the at least one fluid outlet channel, wherein the portion of the wall segment and the fluid outlet channel sleeve (61) complement each other to define the at least one fluid outlet channel (53).

9. The centrifugal pump assembly (1) according to claim 1, wherein: The first mechanical coupling (27) is formed as a corresponding coupling counterpart of a second mechanical coupling (31) for releasably coupling to the second coupling (31) of another pump stage housing segment (7a, b).

10. The centrifugal pump assembly (1) according to claim 1 or 9, wherein: The first mechanical coupling (27) and / or the second mechanical coupling (31) of the one or more pump stage housing segments (7a, b) predefine one or more different rotational mounting positions of the one or more pump stage housing segments (7a, b).

11. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: The first mechanical coupling (27) and the second mechanical coupling (31) define respective coupling partners of the bayonet coupling.

12. The centrifugal pump assembly (1) according to claim 1 or 2, further comprising at least one sealing element (9a-c) for sealing the at least one fluid outlet channel (53).

13. A centrifugal pump assembly (1) according to claim 1 or 2, wherein: The pump head (11) defines a return channel (71) for receiving pumped fluid from one of the one or more impellers (3a-c) and redirecting the pumped fluid to the at least one fluid outlet channel section (53) of one of the pump stage casing sections (7a, b) coupled to the pump head (11).

14. A centrifugal pump assembly (1) according to claim 13, wherein: The pump head (11) is connected to or integral with the motor housing (63), and the return channel (71) extends through the motor housing (63) in thermal contact with heat-generating components of the motor so that the pumped fluid cools the heat-generating components of the motor.

15. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: An axial buffer chamber (59) is provided between a first axial end (55) of the rotor shaft segment (25a-d) and a second axial end (57) of the other rotor shaft segment (25a-d) being coupled thereto for torque transmission between the coupled rotor shaft segments (25a-d).

16. A centrifugal pump assembly (1) according to claim 15, wherein The axial damping chamber (59) is at least partially filled with a damping medium.

17. A centrifugal pump assembly (1) according to claim 1 or 2, wherein: The pump base (5) defines a fluid intake channel extending from the pump inlet (13) to a suction opening (51), wherein the suction opening (51) is arranged coaxially with the rotor axis (z) and laterally surrounds a rotor shaft section (25a) of one of the one or more impellers (3a-c).

18. A centrifugal pump assembly (1) according to claim 17, wherein The pump base (5) defines a tubular element (41) coaxially arranged within the suction bore (51) for receiving the rotor shaft segment (25a) of the impeller (3a), wherein the tubular element (41) provides at least one static inner radial bearing surface (43) in sliding contact with a rotating outer radial bearing surface (45) of the rotor shaft segment (25a) of the impeller (3a).

19. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: The centrifugal pump (1) does not have - a shaft extending from the pump head (11) to the pump base (5), and / or - Tie rods or straps for holding the pump head (11) and the pump base (5) together.

20. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: The impeller outlet (21) faces away from the pump base (5) and the inlet of the guide passage (47) faces the pump base (5), wherein the inlet of the guide passage (47) is arranged to receive the pumped fluid from the impeller outlet (21).

21. The centrifugal pump assembly (1) according to claim 1 or 2, wherein: All of the one or more impellers (3a-c) are identical in shape, size and material.

22. A centrifugal pump assembly (1) according to claim 1 or 2, wherein: All of the one or more pump stage housing segments (7a, b) are identical in shape, size and material.

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