Centrifugal pump with ultrasonic transducers

Abstract

Described and claimed is a pump housing (1) for a centrifugal pump with a pump body (5). The pump housing (1) can be used both for a single-stage and multi-stage centrifugal pumps. The pump body (5) partially surrounds a pump chamber (21) with one or more impellers (3) which rotatable about a drive axis (25). The pump body (5) further defines an axial volute (31) for channeling the flow of pump fluid generated in the pump chamber (21) towards the pressure-side outlet (13) of the pump housing (1). The volute (31) is formed along the drive axis (25) on the same of any circumferential outlets of the one or more impellers (3) as a suction-side inlet (11) of the pump body (5). In the volute (31) at least two ultrasonic transducers (73a to 73d) are integrated that define an ultrasonic flow measurement path (75). The ultrasonic flow measurement path (75) extends entirely in the volute (31) and does not overlap with any circumferential outlet of the one or more impellers (3) along the drive axis (25).

Description

[0001] Applicant: GRUNDFOS HOLDING A / S

[0002] Title: A pump housing fora centrifugal pump Our Ref.: GP 3841 WO

[0003] Description

[0004]

[0001] The present invention is directed to a pump housing for a centrifugal pump with a pump body. The pump body surrounds a pump chamber accommodating one or more impellers rotatable about a drive axis and defines a suction-side inlet for pump fluid, a pressure-side outlet for 5 pump fluid as well as a volute for channeling a flow of pump fluid generated in the pump chamber towards the pressure-side outlet.

[0005]

[0002] The flow provided by a centrifugal pump is commonly estimated on basis of the pump speed or measured using ultrasonic flow meters that are provided upstream or downstream, i.e. in the flow direction 10 ahead of the suctions-side inlet or behind the pressure-side outlet, of the centrifugal pump. Commonly, ultrasonic (US) flow meters are used to measure the flow rate of the pump fluid. Ultrasonic flow meters comprise two ultrasonic transducers that send and receive ultrasonic waves across the flow. The flow rate is calculated, for example, in a time-of-flight method based on the difference in time it takes for the ultrasonic waves to travel with the flow or against the flow. Other ultrasound flow meters rely, for example, on the Doppler effect.

[0006]

[0003] Efforts have also been made to integrate ultrasonic flow meters into centrifugal pumps. For example, EP 2872 781 Bl discloses a pump 20 body of a centrifugal pump with integrated ultrasonic transducers. A plurality of different potential locations for the ultrasonic transducers in the pump body and the resulting ultrasonic flow measurement path are disclosed. However, reducing the disclosure of this patent into practice is

[0007] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026very complicated as the complex flow conditions inside the pump body make accurate flow measurement very challenging.

[0008]

[0004] In DE 102014006743 Al, another example of a centrifugal pump with an integrated ultrasound flow sensor is disclosed. Here, the flow sen5 sor is a single part that can be inserted into a dedicated opening provided in the pump body.

[0009]

[0005] In view of the above, it can be considered an aspect of the present invention to provide a pump housing with integrated ultrasonic flow sensors that enable a precise ultrasonic flow measurement.

[0010] 10

[0006] The problem is solved by a pump housing according to claim 1.

[0011] Preferred embodiments of the pump housing are the subject matter of the dependent claims.

[0012]

[0007] The present invention is generally directed to a pump housing for a centrifugal pump with a pump body. The pump body at least partially 15 surrounds a pump chamber accommodating one or more impellers which are rotatable about a drive axis. The pump body defines an inlet opening for pump fluid, a pressure-side outlet for pump fluid as well as a volute for channeling a flow of pump fluid generated in the pump chamber towards the pressure-side outlet. Each impeller of the one or more impellers comprises an axial inlet aligned with the drive axis and a circumferential outlet. The volute is formed along the drive axis on a same side of any circumferential outlet of the one or more impellers as the inlet opening of the pump body. The pump body comprises an ultrasonic flow measurement path defined between a first ultrasonic transducer and a 25 second ultrasonic transducer. The ultrasonic flow measurement path extends entirely in the volute and does not overlap with any circumferential outlet of the one or more impellers along the drive axis.

[0013] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0008] In other words, the pump housing comprises at least a pump body. The pump body forms at least the lower part of the pump housing. Additional parts of the pump housing may, for example, be a pump top and, inter alia, a sleeve extending between the pump top and the pump 5 body.

[0014]

[0009] The pump body at least partially surrounds one or more impellers which are located in a pump chamber. In other words, the pump housing and, in particular, the pump body may be used for a single-stage pump but could also be used for a multi-stage pump comprising a plu10 rality of stacked impellers. Each of the one or more impellers is rotatably arranged inside the pump housing. The one or more impellers all rotate about the same drive axis which may, for example, extend vertically when the pump housing is placed in an operating position.

[0015]

[0010] The pump body defines an inlet opening for pump fluid. At the 15 inlet opening, the pump fluid which is ingested into the pump flows into the pump chamber. The inlet opening may, for example, be connected to a suction-side inlet of the pump housing. The suction-side inlet could also be formed by the pump body or may be formed by an inlet module that is attached to the pump body. The pump body further comprises a pressure-side outlet for pump fluid. During operation of a pump including the pump housing, the pump fluid is sucked into the pump chamber through the suction-side inlet and inlet opening. The pressurized pump fluid is expelled from the pump housing through the pressure-side outlet.

[0016]

[0011] Using different inlet modules, the pump housing can be config25 ured in different ways. For example, the pump housing can be configured to be of the end-suction type where the suction-side inlet is aligned with the drive axis and extends perpendicular to the pressure-side outlet. In another exemplarily embodiment, the pump housing can be of the inline type where the suction-side inlet and the pressure-side outlet are

[0017] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026aligned and extend in opposite directions perpendicularly away from the drive axis. Also, other configurations are possible.

[0018]

[0012] Each of the impellers that is arranged in the pump chamber comprises an axial inlet and a circumferential outlet. The axial inlet is centered 5 about the drive axis and points towards the inlet opening where the conduit guiding the ingested flow from the suction-side inlet of the pump housing merges into the pump chamber. The circumferential outlet on the other hand is formed at a radial outer region of each of the impellers. The pump fluid flows parallel to the drive axis into the impellers and flows out of the impeller in a direction which has at least a radial component relative to the drive axis. In an exemplarily preferred embodiment, the circumferential outlet faces radially away from the drive axis, i.e., the circumferential outlet forms essentially a cylindrical area about the drive axis. In other embodiments, the one or more impellers are semi-axial im15 pellers where the area of the circumferential outlet forms a frusto-conical shape with the tip of the cone pointing away from the inlet opening of the pump body.

[0019]

[0013] The pump body further comprises a volute which is formed for channeling a flow of pump fluid that is created by the one or more im20 pellers in the pump chamber towards the pressure-side outlet. The flow entering the volute is preferably a rotating or spiraling flow of pump fluid, i.e., the flow may have a circumferential velocity component about the drive axis. In such embodiments, the volute may be asymmetric. For example, cross-sectional area of the volute may increase from an inlet region having a relatively small cross-sectional area towards an outlet region. The cross-sectional area may, for example, be determined along planes that extend through and radially away from the drive axis. At the outlet region, the volute may merge into the pressure-side outlet of the pump body. In the asymmetric volute, the pressurized pump fluid may 30 rotate about the drive axis in a single direction (clockwise or counterclockwise viewed along the drive axis).

[0020] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0014] The pressurized fluid entering the volute may be substantially nonrotating, i.e., the pressurized fluid may flow generally parallel to the drive axis with a reduced or no circumferential velocity component. For example, in a multi-stage pump, guide vanes downstream of a final impeller 5 stage may be configured to reduce or essentially eliminate rotation of the pressurized fluid. The fluid entering the volute may, therefore, be substantially devoid of a rotational component and may not spiral about the drive axis. In such embodiments, the volute may be symmetrical, for example mirror-symmetric with respect to a plane extending through the 10 outlet channel and the drive axis. The volute may have a substantially constant cross-sectional area, except in an outlet region. Alternatively, the cross-sectional area may decrease with increasing distance from the outlet region and may be minimal at a position opposite the outlet region.

[0021]

[0015] In any case, the volute is a so-called axial volute that is placed along the drive axis on the same side of the one or more impellers as the inlet opening where the inlet flow of pump fluid flows into the pump chamber. For example, for a pump housing with a vertically extending drive axis, the volute will be arranged below the one or more impellers 20 and below the pump chamber. The volute is in other words arranged so that the volute does not overlap with any circumferential outlet of an impeller of the one or more impellers when projected onto a plane extending parallel to the drive axis. In consequence, even for an impeller with a circumferential outlet facing radially away from the drive axis, the rotating flow created by the impeller will not flow directly into the volute but needs to cover at least a certain distance in the direction of the drive axis when flowing from the pump chamber to the volute.

[0022]

[0016] Inside the volute at least one ultrasonic flow measurement path is formed. The ultrasonic flow measurement path extends between a first 30 ultrasonic transducer and a second ultrasonic transducer which form an integrated flow measurement sensor. The terms “first” and “second” are Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026used solely as labels for the ultrasonic transducers and do not imply any particular order, arrangement or priority unless explicitly stated otherwise.

[0023]

[0017] The ultrasonic flow measurement path delimited by the first ultrasonic transducer and the second ultrasonic transducer is formed so that 5 it does not overlap with any circumferential outlet of the one or more impellers when projected onto a plane extending parallel to the drive axis. In other words, any flow that comes out of the one or more impellers flows above the ultrasonic flow measurement path and never directly through the ultrasonic flow measurement path.

[0024]

[0018] A pump body may comprise more than one ultrasonic flow measurement path. Each ultrasonic flow measurement path is formed between a different set of ultrasonic transducers, i.e., each ultrasonic flow measurement path commences at a first ultrasonic transducer and terminates at a second ultrasonic transducer. Thus, for each ultrasonic flow 15 measurement path there is a first ultrasonic transducer and a second transducer.

[0025]

[0019] As compared to integrating an ultrasonic flow measurement path in a traditional volute, the arrangement of the ultrasonic flow measurement path in the axial volute positions the measurement path outside 20 the flow coming directly out of the circumferential outlets of the one or more impellers. Further, the flow measurement path is placed along the drive axis axially away from the impeller outlet to increase the distance between the circumferential impeller outlet and the flow measurement path. The greater the distance between the circumferential impeller outlet and the flow measurement path, the more the fluctuations in the velocities measured along the measurement path in the volute are reduced. In contrast, if an ultrasonic flow measurement path is at least partially within the flow coming directly out of the circumferential outlet of a rotating impeller, this essentially renders the signal of the ultrasonic trans30 ducers useless due to the high degree of fluctuations in the signal output Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026provided by the transducers. The signal is useless in the sense that it is unsuitable for providing sufficiently accurate flow measurements.

[0026]

[0020] Further, by placing an ultrasonic flow measurement path entirely in the axial volute the dependency of the flow measurement on the im5 pellerspeed is greatly reduced as compared to an ultrasonic flow measurement path defined in a conventional volute which is positioned in line- of-sight of the circumferential outlet of at least one impeller or at least in close distance of the impeller outlet. In a conventional volute, the measured flow will highly depend on the impeller speed, placing additional 10 uncertainties in interpreting the output of the ultrasonic transducers.

[0027] When the distance between the flow measurement path and the impeller outlet is increased, the measured flow depends significantly less on the impeller speed.

[0028]

[0021] Further, compared to external ultrasonic flow sensors which are placed upstream ordownstream of the centrifugal pump, the conditions under which the ultrasonic flow measurement path is operated are less affected by changes in the system condition as the flow profile in the volute is less affected by the system conditions. This results in more predictable flow measurements in the axial volute. For example, the meas20 urement results of an ultrasonic flow measurement path in an axial volute are less affected by system conditions such as valves or bents in the inlet or outlet pipe of the pump housing as compared to flow measurements taken in flow pipes which are placed outside of the pump housing.

[0029]

[0022] Additionally, an axial volute allows an efficient utilization of a modular pump house design. As previously noted, the pump housing can be used both in an end-suction pump configuration and an inline pump configuration simply by using different inlet modules. The accuracy and effectiveness of the ultrasonic flow measurement is not affected by the pump configuration. Further, the calibration of the ultrasonic transducers 30 and the ultrasonic flow sensor formed by the first and second ultrasonic Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026transducer is less dependent on the number of impellers in the pump housing which makes the ultrasonic flow measurement path suitable for both single and multi-stage pumps.

[0030]

[0023] In this regard, it is noted that the axial volute is formed in the pump 5 body so that regardless as to whether the pump body is used fora single- stage centrifugal pump or for a multi-stage centrifugal pump, the volute is never positioned within line-of-sight of the circumferential outlet of each of the one or more impellers. For example, the pump body can be used for a single-stage centrifugal pump. In this embodiment, the rotat10 ing flow created by the single impeller does not directly flow into the axial volute. The same applies when the pump body is used for a multi-stage centrifugal pump. Here, the flow from none of the impellers will directly flow into the volute.

[0031]

[0024] In a preferred embodiment, the pump housing is configured for redirecting a flow of pump fluid flowing outwardly away from the drive axis out of the circumferential outlet of one impeller of the one or more impellers towards the volute. Preferably, the pump housing comprises a pump top with a curved inner surface for redirecting the outwardly flowing flow into a flow of pump fluid flowing towards the volute. Alternatively 20 or additionally, the pump housing preferably comprises a plurality of guide vanes for redirecting the outwardly spiraling flow into a rotating flow of pump fluid flowing generally parallel to the drive axis towards the volute.

[0032]

[0025] Thus, in the preferred embodiment the pump housing comprises means which redirect the pump fluid accelerated outwards by the last impeller arranged in an impeller stack or the only impeller in the pump chamber towards the volute. For example, the pump housing may comprise a pump top delimiting the pump chamber on an opposite site from the pump body. The pump top may comprise a curved inner surface 30 which supports and facilitates the change in direction of the outwardly Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026spiraling flow that has been created by the one or more impellers. Alternatively or additionally, the pump housing may comprise a plurality of guide vanes which redirect the outwardly flowing or outwardly spiraling flow from the one or more impellers towards the volute. The guide vanes 5 and the curved inner surface condition the flow so that a more uniform or at least more predictable flow already reaches the volute. Thereby, a more accurate flow measurement along the ultrasonic flow measurement path in the axial volute is possible.

[0033]

[0026] In a preferred embodiment, the pump housing comprises a volute 10 separator. The volute separator is located along the drive axis between the one or more impellers and the volute. The volute separator is configured for partially separating the pump chamber from the volute, thereby reducing a radial width of a flow channel for pump liquid between the pump chamber and the volute. The volute separator is located along the drive axis between the one or more impellers and the ultrasonic flow measurement path.

[0034]

[0027] In other words, in the preferred embodiment the pump housing comprises a volute separator. The volute separator may be formed by an insert that is placed in the pump body but can also be formed inte20 grally with the pump body. The volute separator serves to limit the width of the flow channel through which pump liquid can flow from the pump chamber into the volute. In other words, the volute separator narrows the cross-sectional area inside the pump body that is available for pump liquid when the pump liquid flows from the chamber to the volute. The vol25 ute separator further serves to improve the flow conditions in the volute to improve flow measurements along the ultrasonic flow measurement path that is defined in the axial volute.

[0035]

[0028] In a preferred embodiment, the separator sectionally defines an inner circumferential surface delimiting the flow channel between the

[0036] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026pump chamber and the volute towards the drive axis. The inner circumferential surface extends generally parallel to the drive axis and / or parallel to an outer circumferential surface delimiting the flow channel between the pump chamber and the volute away from the drive axis.

[0037] 5

[0029] In the preferred embodiment the volute separator extends not only perpendicular to the drive axis but has also an axial extension. This part of the volute separator forms an inner circumferential surface which delimits the flow channel between the pump chamber and the volute towards the drive axis. The inner circumferential surface thus defines the 10 minimum distance of the flow channel between the pump chamberand the volute. In the preferred embodiment, the circumferential surface extends generally parallel to the drive axis. In other words, the surface is at least partially cylindric.

[0038]

[0030] Alternatively or additionally, the inner circumferential surface extends parallel to an outer circumferential surface which delimits the flow channel between the pump chamber and the volute on a side facing away from the drive axis. Thus, in the preferred embodiment the surfaces delimiting the flow channel from the pump chamber to the volute extend parallel and sectionally define a flow channel of constant width.

[0039] 20 This further serves to stabilize and condition the flow in the volute, thereby improving the accuracy that can be achieved within the ultrasonic flow measurement path.

[0040]

[0031] In an alternative embodiment, the inner circumferential surface is tilted with regard to the drive axis. The tilt of the inner circumferential surface is so that the distance of the inner circumferential surface from the drive axis decreases in the direction away from the pump chamber. For example, the inner circumferential surface may be formed as a frusto- conical surface. The changing distance of the inner circumferential surface from the drive axis does not have to be constant or continuous. The 30 shape change could also be stepwise or curved.

[0041] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0032] In each of the above embodiments, the inner circumferential surface is formed by the volute separator. The outer circumferential surface may, for example, be formed by the pump body or by a sleeve extending between the pump body and a pump top. This sleeve may, in par5 ticular, be used in case the pump housing is configured as a multi-stage centrifugal pump.

[0042]

[0033] In a preferred embodiment, the pump housing comprises an outer circumferential guide surface extending generally parallel to the drive axis and delimiting the flow channel between the pump chamber and the volute on a side facing away from the drive axis. The outer circumferential guide surface is preferably at least partially formed by at least one of a pump top of the pump housing, a sleeve extending between the pump top and the pump body, and the pump body. The outer circumferential guide surface further improves the flow conditions in the 15 volute and, thereby, the accuracy of the flow measurement that can be achieved along the ultrasonic flow measurement path.

[0043]

[0034] In a preferred embodiment, a distance of the first ultrasonic transducer from each circumferential outlet of the one or more impellers along the drive axis is less than a distance of the second ultrasonic trans20 ducer from the respective circumferential outlet of the one or more impellers along the drive axis. In other words, in the present embodiment the flow measurement path extending between the first and second ultrasonic transducer does not extend perpendicular to the drive axis but is tilted with regard to any plane that is perpendicular to the drive axis. The first ultrasonic transducer may be arranged upstream of the second transducer or downstream of the second transducer. The terms upstream and downstream are used with regard to the regular flow direction of the flow in a centrifugal pump formed using the pump housing is in operation. In an exemplary preferred embodiment, the first ultrasonic trans30 ducer is arranged upstream of the second ultrasonic transducer, thus the

[0044] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026pump flow passes the first ultrasonic transducer before passing the second ultrasonic transducer. Ultrasound emitted by the first ultrasonic transducer thus travels generally with the flow whereas ultrasound emitted by the second ultrasonic transducer travels generally against the flow direc5 tion of the pump fluid.

[0045]

[0035] It is further preferred that the ultrasonic flow measurement path is formed as a direct line-of-sight path between the first ultrasonic transducer and the second ultrasonic transducer. Thus, in the preferred embodiment there are no reflective surfaces between the first ultrasonic 10 transducer and the second ultrasonic transducer. Thereby, the ultrasound emitted by the first ultrasonic transducer is directly received at the second ultrasonic transducer and ultrasound emitted by the second ultrasonic transducer is directly received at the first ultrasonic transducer.

[0046]

[0036] Alternatively, the ultrasonic flow measurement path is formed as 15 an indirect path comprising at least one reflective surface on the ultrasonic flow measurement path between the first ultrasonic transducer and the second ultrasonic transducer. Thus, in the preferred embodiment ultrasound emitted by the first ultrasonic transducer is reflected by at least one reflective surface in the volute of the pump body before it is received at the second ultrasonic transducer. Likewise, ultrasound emitted by the second ultrasonic transducer is reflected by at least one reflective surface in the volute before it is received at the first ultrasonic transducer.

[0047]

[0037] It is noted that while an ultrasonic flow measurement path cannot 25 be both a direct line-of-sight path and an indirect path, the same pump housing may comprise multiple ultrasonic flow measurement paths. For example, a pump housing may comprise a first ultrasonic flow measurement that is formed as a direct line-of-sight path and a second ultrasonic flow measurement path that is formed as an indirect path. Measuring the

[0048] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026flow along two different flow measurement paths and combining the results increases the accuracy of the measured flow.

[0049]

[0038] In a preferred embodiment, the at least one reflective surface is part of the pump body. Alternatively, the at least one reflective surface 5 is part of the volute separator, wherein the volute separator is located along the drive axis between the one or more impellers and is configured for partially separating the pump chamber from the volute. Further alternatively, the at least one reflective surface is part of the outer circumferential guide surface extending generally parallel to the drive axis and 10 delimiting the flow channel between the pump chamber and the volute on a side facing away from the drive axis. Further alternatively, the at least one reflective surface may be an insert that is placed inside the volute.

[0050]

[0039] In other words, the one or more reflective surfaces that are part of an indirect ultrasonic flow measurement path can be part of different elements of the pump housing. Since the volute is part of the pump body, the reflective surface can also be formed as part of the pump body. For example, a part of an inner volute surface delimiting the volute towards the drive axis or an outer volute surface delimiting the volute in a direc20 tion facing away from the drive axis could be machined to serve as a reflective surface provided that the volute is from a suitable material such as a metall. In other embodiments, a reflective element can be attached to or placed on the pump body that serves as one or more reflective surface. Likewise, the reflective surfaces can be attached to or formed on the volute separator or an outer circumferential drive surface. In both of these examples, the respective reflective surface needs to be attached to be part of the pump housing so that it reaches the volute. The reflective surface formed on the volute separator or the outer circumferential volute surface could be machined parts or could also be 30 (integrated) elements that are of a material with a particularly high reflectivity for ultrasound.

[0051] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0040] For the sake of completeness, it is pointed out that reflective surfaces can be positioned both on surfaces that delimit the volute towards the drive axis, i.e., one of the inner volute surfaces, as well as on surfaces that delimit the volute away from the drive axis, i.e., one of the outer 5 volute surfaces. Alternatively, it is also possible that the reflective surface is placed on one of the outer surfaces delimiting the volute away from the drive axis but could also be formed within the flow channel. For example, the reflective surface could be placed on a flow conditioning element that is arranged in the volute as will be explained later.

[0052] 10

[0041] In a preferred embodiment, a reflective surface of the at least one reflective surface is located directly adjacent to the first ultrasonic transducer or the second ultrasonic transducer. Hence, in the preferred embodiment the ultrasonic flow measurement path comprises at least one reflective surface that is placed directed adjacent to the first or the second ultrasonic transducer of the respective flow measurement path. The reflective surface is configured to redirect the ultrasonic waves emitted by the directly adjacent transducer immediately adjacent to the respective transducer. This facilitates the installation of the ultrasonic transducers as the ultrasonic transducer does not have to point directly at the 20 other transducer or at a reflective surface located in the middle of the flow measurement path.

[0053]

[0042] Further preferably, the ultrasonic flow measurement path comprises at least two reflective surfaces. A first reflective surface of the at least two reflective surfaces is located directly adjacent to the first ultrasonic transducer. A second reflective surface of the least two reflective surfaces is located directly adjacent to the second ultrasonic transducer. A distance between the first reflective surface and the second reflective surface exceeds the distance between the first ultrasonic transducer and the first reflective surface and the distance between the second ultra30 sonic transducer and the second reflective surface.

[0054] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0043] In other words, in the preferred embodiment the flow measurement path comprises at least two reflectors or reflective surfaces which are each placed in direct vicinity of one of the ultrasonic transducers. Each of the ultrasonic transducers is associated with one reflective sur5 face. The reflective surfaces are used to redirect the ultrasonic waves emitted by the transducers or received by the transducers immediately adjacent to the respective transducer. This facilitates the installation of the ultrasonic transducers as they do not have to point directly at each other or at a reflective surface located in the middle of the flow meas10 urement path.

[0055]

[0044] For example, at least one of the first reflective surface and the second reflective surface can be located in a bore that branches of the actual volute, i.e., the first reflective surface and / orthe second reflective surface is located outside of the flow of pressurized pump fluid that is 15 channeled in the volute towards the pressure-side outlet of the pump body. As previously discussed, the first reflective surface and / or the second reflective surface can be formed directly by the pump body, i.e., an inner surface of the pump body forms the reflective surface. Alternatively, at least one of the first reflective surface and the second reflective surface can be formed as an insert that is placed, for example, in a dedicated bore in the pump body or inserted into the same bore as the associated ultrasonic transducer.

[0056]

[0045] The first and second ultrasonic transducers can be arranged in either an outer volute wall delimiting the volute in a direction facing away 25 from the drive axis or an inner volute wall delimiting the volute towards the drive axis. For constructional reasons, placing the ultrasonic transducers for example in a bore formed in the outwards facing inner surface of the volute is preferred. However, integrating ultrasonic transducers in a bore in the inner volute wall is also a viable option.

[0057] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0046] Consequently, in a preferred embodiment the first ultrasonic transducer is located in an outer volute wall delimiting the volute on a side facing radially away from the drive axis or in an inner volute wall delimiting the volute towards the drive axis. Likewise, the second ultrasonic 5 transducer is located in the outer volute wall or in the inner volute wall.

[0058]

[0047] In a preferred embodiment, the pump housing comprises at least one flow conditioner located in the volute. The flow conditioners are provided to further stabilize the flow, thereby increasing the accuracy and the reliability of the flow measurements made along the ultrasonic flow 10 measurement path in the axial volute.

[0059]

[0048] The at least one flow conditioner is preferably formed as an insert placed in the volute. Such an insert can be a separate part that is inserted into the volute. Alternatively, the at least one flow conditioner is part of the volute separator. As previously mentioned, the volute sepa15 rator is located along the drive axis between the one or more impellers and is configured for partially separating the pump chamber from the volute. Alternatively, the at least one flow conditioner is attached to guide vanes formed at a pump top. The guide vanes are configured for redirecting a flow of pump fluid flowing out of the circumferential outlet of one of the impellers of the one or more impellers towards the volute. Thus, different kinds of flow conditioners are possible.

[0060]

[0049] The flow conditioners may be formed as a plane extending radially about the drive axis and may have a lateral extension that is either parallel to the drive axis or perpendicular to the drive axis. A pump hous25 ing may comprise one or more flow conditioners of different kinds. In other words, the at least one flow conditioner extends on an arc about the drive axis and perpendicular or parallel to the drive axis.

[0061]

[0050] In another preferred embodiment, the volute is configured to limit a recirculation of pump fluid. Hence, in the preferred embodiment the Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026volute is shaped so that the pump fluid preferably takes only a single revolution in the volute before exiting the volute towards the pressure-side outlet of the pump body. By reducing or preferably preventing recirculation of pump fluid the flow measurement along the ultrasonic flow 5 measurement path may be further improved.

[0062]

[0051] The volute extends circumferentially between an inlet region and an outlet region where the volute merges into the pressure-side outlet of the pump body. Preferably, a radial width of the volute about the drive axis increases from the inlet region to the outlet region for further limiting a recirculation of pump fluid. In other words, in the preferred embodiment the volute is an asymmetric volute which is narrower at the inlet region as it is in the outlet region. The inlet and outlet region are defined by their distance in the flow direction from the volute to the conduit or channel connecting the volute to the pressure-side outlet of the pump 15 body. The inlet region of the axial volute is directly adjacent to the outlet region of the axial volute in the flow direction.

[0063]

[0052] The radial width of the volute can be varied by changing the distance of an inner volute wall or an outer volute wall from the drive axis. In a preferred embodiment, a maximum distance of the outer volute wall 20 from the drive axis is, however, constant, whereas a distance of the inner volute wall from the drive axis decreases from the inlet region to the outlet region. In other words, it is preferred for the maximum distance of the outer volute wall from the drive axis which also defines the maximum radial dimensions of the pump body to be essentially constant. For varying the radial width of the volute, the distance of the inner volute wall is instead modified. The inner volute wall delimits the volute towards the drive axis. To this end, an insert may, for example, be placed in the volute. The insert may, for example, be part of the volute separator. Alternatively, or additionally, the pump body may comprise a dedicated volute narrow30 ing wall that is formed integrally with the pump body.

[0064] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0053] Additionally, or alternatively, the volute preferably comprises a bottom surface delimiting the volute in a direction facing away from the one or more impellers. The maximum distance of the bottom surface from the one or more impellers increases from the inlet region to the out5 let region. Thus, in the preferred embodiment recirculation in the volute is limited by employing a volute with a tilted bottom surface. The bottom surface extends helically about the drive axis so that the distance of the bottom surface from the pump chamber increases from the inlet region of the volute to the outlet region thereof. All of the above elements that 10 are provided for limiting a recirculation of pump fluid intend to generally provide a volute with a smaller cross-sectional area in the inlet region with the cross-sectional area increasing towards the outlet region. The cross-sectional area may, for example, be determined along planes that extend through and radially away from the drive axis.

[0065] 15

[0054] Subsequently, the invention will be described in more detail with reference to drawings, wherein:

[0066] Fig. 1 shows a perspective view of a first exemplary embodiment of a pump housing configured for a single-stage centrifugal pump,

[0067] 20 Fig. 2 shows a perspective view of a second exemplary embodying of a pump housing configured for a doublestage centrifugal pump,

[0068] Fig. 3 shows a perspective, partially cut view of the exemplary embodiment shown in figure 1 with a first ultrasonic flow 25 measurement path highlighted,

[0069] Fig. 4 shows a top view of the exemplary embodiment shown in figure 3,

[0070] Fig. 5 shows a sectional view to the pump body of the exemplary embodiment shown in figures 3 and 4,

[0071] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026Fig. 6 shows a perspective, partially cut view of the exemplary embodiment shown in figure 3 with a second ultrasonic flow measurement path highlighted,

[0072] Fig. 7 shows a top view of the exemplary embodiment shown 5 in figure 6,

[0073] Fig. 8 shows a sectional view of the exemplary embodiment shown in figure 1 with a reflective surface,

[0074] Fig. 9 shows a sectional view of the exemplary embodiment shown in figure 1 with another reflective surface, Fig. 10 shows a perspective view of another embodiment of a pump housing with an indirect ultrasonic flow measurement path,

[0075] Fig. 11 shows a sectional view of the exemplary embodiment of a pump housing shown in figure 1 with another reflective 15 element,

[0076] Fig. 12 shows a sectional view of the exemplary embodiment of a pump housing shown in figure 1 with an exemplary embodiment of a flow conditioning element,

[0077] Fig. 13 shows a sectional view of the exemplary embodiment of 20 a pump housing shown in figure 1 with another exemplary embodiment of a flow conditioning element, Fig. 14 shows a perspective view of another exemplary embodiment of a pump body,

[0078] Fig. 15 shows a partial sectional view of another exemplary embodying of a pump housing configured fora multi-stage centrifugal pump which comprises the exemplary embodiment of pump body shown in figure 14,

[0079] Fig. 16 shows a first sectional view of the exemplary embodiment of a pump body shown in figure 14,

[0080] 30 Fig. 17 shows a second sectional view of the exemplary embodiment of a pump body shown in figure 14,

[0081] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026Fig. 18 shows a sectional view of an exemplary embodiment of an ultrasonic flow measurement path in a volute, and Fig. 19 shows a sectional view of another exemplary embodiment of an ultrasonic flow measurement path in a vol5 ute.

[0082]

[0055] Figure 1 shows an exemplary embodiment of a pump housing 1 for a centrifugal pump. The pump housing 1 is configured to be used as a single-stage centrifugal pump, i.e., the pump housing 1 comprises a single impeller 3. The pump housing 1 comprises a pump body 5 and a 10 pump top 7. Further, the pump housing 1 comprises a motor stool 9 for connecting the pump housing 1 to a pump motor (not shown). The pump motor may be an electric motor.

[0083]

[0056] The pump body 5 comprises a suction-side inlet 11 and a pressureside outlet 13. The suction-side inlet 11 is formed by an inlet adapter 15 15 that is connected to a central inlet channel 17 of the pump body 5. The central inlet channel 17 terminates at an inlet opening 19 towards a pump chamber 21 of the pump housing 1. The pump chamber 21 designates the area where the impeller 3 is rotatably arranged.

[0084]

[0057] The impeller 3 is attached to a drive shaft 23 and rotatable at 20 about a drive axis 25. The central inlet channel 17 and the inlet opening 19 of the pump body 5 are aligned with the drive axis 25. The impeller 3 comprises an axial impeller inlet 27 that is aligned with the inlet opening 19 of the pump body 5. Further, the impeller 3 comprises a circumferential outlet 29. The circumferential outlet 29 essentially forms a cylindrical 25 area about the drive axis 25.

[0085]

[0058] Pump fluid that is ingested through the suction-side inlet 11 and the central inlet channel 17 into the pump chamber 21 is accelerated by the impeller 3 and leaves the circumferential outlet 29 of the impeller

[0086] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 20263 as a spiraling radial flow. For redirecting the spiraling flow towards a volute 31 formed in the pump body 5, the pump top 7 comprises a curved outer guide surface 33, a curved inner guide surface 34 and a plurality of guide vanes 35. The curved outer guide surface 33, the 5 curved inner guide surface 34, and the guide vanes 35 channel and redirect the flow towards the axial volute 31 which is formed below the pump chamber 21. The outer and inner guide surface 33, 34 essentially define a curved, ring-shaped channel directing the flow from the impeller 3 towards volute 31. The guide vanes 35 are arranged in this channel.

[0087] 10 The inner guide surface 34 delimits the channel towards the drive axis 25, whereas the outer guide surface 33 delimits the channel away from the drive axis 25.

[0088]

[0059] In other words, the volute 31 is formed on the same side of the impeller3 as the inlet opening 1 of the pump body 5. Placing the volute 31 axially in another section of the pump body 5 as the pump chamber 21 generally allows to limit the radial dimensions of the pump housing 1 as the volute 31 does not add to the maximum diameter of the pump housing 1. As can be seen in figure 1 , the volute 31 is configured so that it is at least partially overlapping with the impeller 3 when projected onto 20 a plane extending perpendicular to the drive axis 25. In other words, an inner volute wall is at least partially closer to the drive axis 25 as the circumferential outlet 29 of the impeller 3.

[0089]

[0060] In the present embodiment, the volute 31 is used for measuring a flow of pump fluid that is provided by the centrifugal pump which comprises the pump housing 1. Details of the corresponding locations of ultrasonic transducers that are required for measuring the flow as well as potential ultrasonic flow measurement paths are discussed in more detail with reference to figures 3 to 13. Several elements of the pump housing 1 and, in particular, the pump body 5 are shaped to improve the reliabil30 ity and accuracy of the flow measurements made in the axial volute 31.

[0090] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0061] For example, the outer guide surface 33, the inner guide surface 34, and the guide vanes 35 serve to improve the uniformity of the flow in the volute 31. Thereby, the accuracy of the flow measurement is improved. The volute is not in line-of-sight of the circumferential outlet 29 of 5 the impeller 3. This reduces the impact of flow variations and in particular of the impeller3.

[0091]

[0062] To further improve the accuracy of the flow measurement, the volute 31 is shaped to reduce recirculation of pump fluid. To this end, a radial width of the volute 31 increases from an inlet region of the volute 10 31 to an outlet region of the volute 31. At the outlet region the volute 31 merges into the conduit connecting the volute 31 to the pressure-side outlet 13 of the pump body 5. As can be seen in figure 1 , the volute 31 is sectionally delimited by a dedicated narrowing wall 37 which forms part of an inner volute wall 39 in the inlet region. Towards the outlet region another part of the inner volute wall 39 is formed by a tubular wall 41 of the pump body 5 surrounding the central inlet channel 17. Thus, a radial distance of the inner volute wall 39 from the drive axis 25 decreases from the inlet region to the outlet region of the volute 31. The maximum radial distance of the outer volute wall 31 which is always formed by the pump 20 body 5 is contrast towards nearly constantly between the inlet region and the outlet region of the volute 31.

[0092]

[0063] Recirculation of the pump fluid in the volute 31 is further prevented by forming a helical bottom surface 45 of the volute 31. The distance of the bottom surface 45 from the impeller 3 increases along the drive axis 25 from the inlet region to the outlet region of the volute 31. Both the change in the radial width and the axial side of the volute 31 not only serve to prevent recirculation but also improves the flow uniformity in the volute 31 as the flow rate increases through the cross sections of the volute 31. Both aspects generally can be attributed to improving flow meas30 urements using ultrasound in the volute 31.

[0093] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0064] Further improvement of the accuracy of the flow measurements is achieved by using a volute separator 47. The volute separator 47 is placed between the pump chamber 21 and the volute 31. It is generally L-shaped in a radial direction, thus forming an upper wall 49 of the volute 5 31 and also delimiting a flow channel 51 between the pump chamber 21 and the volute 31. This is achieved by a radially outer wall 53 of the volute separator 47 that is formed parallel to the drive axis 25 and forms an inner cylindrical surface 55 delimiting the flow channel 51 towards the drive axis 25. The inner cylindrical surface 55 extends on a radius about 10 the drive axis 25 that is further away from the drive axis 25 as the circumferential outlet 29 of the impeller 3. The inner cylindrical surface essentially forms an extension of the inner guide surface 34 formed at the pump top 7. The flow channel 51 is further delimited by an outer cylindrical surface 57 that is formed in the exemplary embodiment shown in figure 1 as an extension of the outer guide surface 33 of the pump top 7. The combination of the pump top 7 with the guide vanes 35 and the narrow flow channel 51 formed between the inner cylindrical surface 55 and the outer cylindrical surface 57 further improves the flow conditions in the volute 31 , thereby allowing the fluid flow measurements.

[0094] 20

[0065] Figure 2 shows a second exemplary embodiment of a pump housing 1. The pump housing 1 shown in figure 2 is configured for a multi-stage centrifugal pump and, in particular, for a double-stage centrifugal pump. The pump housing 1 comprises an identical pump body 5, a pump top 7 and motor stool 9. Also, the inlet adapter 15 is identical. For 25 the sake of completeness it is noted that in figures 1 and 2 the pump housing 1 is configured as being of the inline pump type. Further, by replacing the inlet adapter 15 with a different part, the pump housing 1 could be adapted as an end-suction type of pump housing. Further, the pump housing 1 shown in figure 2 also comprises the volute separator 47.

[0095] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0066] The pump housing 1 has been adapted to be used for a multistage centrifugal pump by placing an impeller chamber 59 with an impeller 3a for the first impeller stage in the pump chamber 21. The impeller chamber 59 comprises inter alia guide vanes 61 redirecting the flow cre5 ated by the first or initial stage impeller 3a towards the second or final stage impeller 3b. The flow created by the second stage impeller 3b is redirected by the inner guide surface 43 and the guide vanes 35 formed at the pump top 7 towards the volute 31.

[0096]

[0067] Further, in the exemplary embodiment shown in figure 2, the flow 10 channel 51 between the pump chamber 21 and the volute 31 is not only formed by the volute separator but also by a sleeve 63 which is placed between the pump top 7 and the pump body 5. While the sleeve 63 extends the outer wall 53 delimiting the pump chamber 21 on a side facing radially away from the drive axis 25, a housing 65 of the impeller chamber 59 extends the inner cylindrical surface 55 of the volute separator 47 and delimits the flow channel 51 thus sectionally towards the drive axis 25.

[0097]

[0068] In all other aspects the exemplary embodiment of a pump housing 1 as shown in figure 2 corresponds to the exemplary embodiment of 20 a pump housing 1 as shown in figure 1. In particular, the pump housing allows accurate flow measurements in the axial volute 31 along a flow measurement path that is entirely within the volute 31 and does not overlap with any circumferential outlet 29 of one of the impellers 3a, 3b.

[0098]

[0069] Figures 3 to 5 show detailed views of the exemplary embodiment 25 of a pump housing 1 shown in figure 1. Figures 3 and 4 show the pump housing 1 in a partially cut view where parts of the motor stool 9 and the pump top 7 have been removed. In figure 5 only the pump body is shown. To avoid unnecessary repetitions, details that have already been

[0099] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026described with regard to figure 1 of the pump housing 1 will not be repeated. Further, not all reference numerals from figure 1 have been incorporated into figures 3 to 5 to keep the figures intelligible.

[0100]

[0070] Firstly, it is pointed out that in figure 3 the inlet region 67 as well as 5 the outlet region 69 of the volute 31 are shown. As previously mentioned, at the outlet region 69 the volute 31 transitions into the conduits connecting to the pressure-side outlet 13 of the pump housing 1.

[0101]

[0071] Furthermore, the pump body 5 shown in figures 3, 4 and 5 comprises four openings or bores 71a to 71 d for receiving ultrasonic transducers 73a to 73d. The ultrasonic transducer 73a forms together with the ultrasonic transducer 73b a first set of ultrasonic transducers 73a, 73b. In other words, the first ultrasonic transducer 73a and the second ultrasonic transducer 73b together form a first flow sensor 74a. Subsequently, the ultrasonic transducer 73a will be designated as the first ultrasonic trans15 ducer 73a and the ultrasonic transducer 73b will be designated as the second ultrasonic transducer of the first set of ultrasonic transducers 73a, 73b. The ultrasonic transducers 73a, 73b are arranged in the pump body 5 so that a first ultrasonic flow measurement path 75 is formed between the two ultrasonic transducers 73a, 73b. The first flow measurement path 75 is a direct line-of-sight path, i.e., ultrasounds emitted by the first ultrasound transducer 73a is directly received by the second ultrasound transducer 73b and vice versa. Provided that sufficient space is available for mounting the transducers 73a, 73b in the pump body, a direct line-of- sight flow measurement path 75 enables an overall simpler integration of 25 the flow measurement sensor into he pump as, for example, no reflectors and no complex angles are required. Further, it is easier to align the measuring path 75 with the complex local velocity fields often found in pumps in contrast to traditional flow meters mounted, for example, in straight pumps.

[0102] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0072] As can be taken from figure 3, that the flow measurement path 75 is entirely closed within the volute 31. Thus, it does not overlap with the circumferential outlet 29 of the impeller 3 in the axial direction. Also, as not in direct line-of-sight of the circumferential outlet 29 of the impeller 3.

[0103] 5 Rather, the ultrasonic flow measurement path 75 is shielded from the outlet 29 by the volute separator 47.

[0104]

[0073] For the sake of completeness, it is noted that figures 3 to 5 show only an example and a pump housing may comprise one, two, or more flow measurement paths. Placing two flow measurement paths in the 10 same volute represents a preferred implementation. However, depending on the embodiment and requirements, one (direct or indirect) flow measurement path may be sufficient to obtain sufficiently accurate flow measurements. In other embodiments, three or even more flow measurements paths may be required.

[0105]

[0074] The first ultrasonic flow measurement path 75 between the first ultrasonic transducers 73a, 73b is also shown in figure 4. Figure 4 is a top, partially cut view of the exemplary embodiment of a pump housing 1 shown in figure 3. In addition to the first ultrasonic flow measurement path 75, figure 4 shows how the axial volute 31 has been shaped to minimize 20 recirculation of the pump fluid in the volute 31. In particular, the shape of the narrowing wall 37 which branches of the tubular wall 41 surrounding the central inlet channel 17 (not shown) is visible in figure 4. It can thus be seen particularly well that the radial width of the volute 31 is significantly lower in the inlet region 67. The tub 77 formed by the narrow wall 37 is covered by the volute separator 47 so that it does not disturb the flow of pump fluid. The cut view in figure 4 also shows that the outer diameter of the pump body 5 is essentially constant in the region of the volute 31.

[0106]

[0075] Figure 5 shows only the pump body 5 of the pump housing 1 shown 30 in figures 3 and 4. The pump body 5 has been partially cut along the first Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026ultrasonic flow measurement path 75. Here, it can be seen particularly well, that the first ultrasonic flow measurement path is tilted with regard to a vertical axis 78 which extends parallel to the drive axis 25. In other words, the distance of the first ultrasonic transducer 73a along the verti5 cal axis 78 is less than the distance of the second ultrasonic transducer 73b along the vertical axis 78. The first ultrasonic flow path 75 thus extends along a plane that is tilted with regard to the drive axis 25 and the vertical axis 78. From figure 5 it can be seen, that the tilted angle of the first ultrasonic flow path 75 roughly follows the tilted angle of the bottom surface 10 45 of the volute 31. This further improves the accuracy of flow measurements along the flow path 75.

[0107]

[0076] Figures 6 and 7 correspond to figures 3 and 4 and show the identical pump housing 1. The only difference between figures 3 and 4 on the one hand 6 and 7 on the other hand is that in figures 6 and 7 the second ultrasonic flow measurement path 79 is shown. The second ultrasonic flow measurement path 79 is an indirect path. An indirect or reflective flow measurement path 79 with one or more reflective surfaces 81 enables higher design freedom and the possibility of mounting transducers 73a to 73s in pump designs with many geometrical constraints. Laos, in20 direct flow measurement paths enable multi-path probing which gives more data on the velocity field distribution of complex local velocities often found in pump chamber and volutes as compared to traditional flow meters with straight pipes. A combination of a direct line-of-sight measurement path and an indirect configuration further enables even higher levels of multipath velocity probing and thus higher accuracies.

[0108]

[0077] All ultrasonic transducers 73a to 73d are formed in the outer volute wall 43. While the first pair of ultrasonic transducers 73a, 73b forms a direct line-of-sight measurement path, the ultrasonic transducers 73c, 73d forming the second pair of ultrasonic transducers 73c, 73d are both 30 pointed towards a reflective surface 81. The reflective surface 81 is formed in the exemplary embodiment shown in figures 6 and 7 by the Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026tubular wall 41 which is part of the inner volute wall 39. The reflective surface 81 can be flat or planar but could also have an optimized shape such as a concave shape focusing the ultrasound waves onto the receiving transducer 73c, 73d. Ultrasound waves emitted by the first ultra5 sonic transducer 73c are directed towards the rejective surface 81, reflected by the reflective surface 81 under the reflection angle 83 and received by the second ultrasonic transducer 73d. In the opposite direction, ultrasound is emitted by the second ultrasonic transducer 73d, reflected by the reflective surface 81 under the reflection angle 83 and 10 receive by the first ultrasonic transducer 73c. The first ultrasonic transducer 73c and the second ultrasonic transducer 73d form a second integrated flow sensor 74b.

[0109]

[0078] In the exemplary embodiment shown in figures 6 and 7, the reflective surface 81 is formed by the pump body 5. However, as shown in figure 8 and 9 the reflective surface 81 could also be a surface 85 which is integrated into the inner volute wall 39 or could be an attached reflective surface 87 that is part of the volute separator 47. Using reflective surfaces that are not made of the same material as the pump body 5 may improve the reflectivity of the reflective surface. For example, in case the 20 pump body 5 is not made of a material that has a high reflectivity for ultrasound or in case the position of the reflective surface 81 cannot be machined to the degree necessary, using a reflective surface 85, 87 that is attached to the volute separator wall 47, the pump top 7 or a sleeve between the pump body 5 and the pump top 7 allows providing a reflective surface made from a highly reflective surface.

[0110]

[0079] Figure 10 shows another exemplary embodiment of a pump body 5. The pump body 5 also has an axial volute 31 and could be used to replace the pump body 5 as shown in figure 1 to 9. In order to avoid unnecessary repetitions, only differences to the pump body 5 will be de30 scribed in more detail. The differences between the two embodiments are, in particular, that the volute 31 does not have a narrowing wall 37. Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026Instead, the inner volute wall 39 is located between the inlet region 67 and the outlet 69 entirely provided by the tubular wall 41 surrounding the central inlet channel 17. The only means to reduce the recirculation in the volute 31 that is used in the exemplary embodiment of a pump body 5 5 as shown in figure 10 is a helical bottom surface 45.

[0111]

[0080] The pump body 5 further comprises a first wall 71a comprising an ultrasonic transducer 73a and a second wall 71 b comprising a second ultrasonic transducer 73b. Between the two ultrasonic transducers 73a, 73b an indirect ultrasonic flow measurement path 89 is formed. The indi10 rect ultrasonic flow measurement path flow comprises a single reflective surface 81 that is molded as part of the outer volute wall 43 formed by the pump body 5. Thus, in the exemplary shown in figure 10, the indirect ultrasonic flow measurement path is not formed via a reflection on the inner volute wall 49 but via a reflection on the outer volute wall 43 allowing a generally longer ultrasonic measurement path 89.

[0112]

[0081] As shown in figure 11 , a reflective surface 81 could also be formed as an attached reflective surface 87 that is part of the pump top 7. In figure 11 , a pump body 5 is of generally similar design to the pump body 5 shown in figure 1. In all other aspects, the pump housing 1 shown in 20 figure 11 corresponds to the exemplary embodiment of a pump housing 1 as shown in figure 1. Therefore, for the sake of brevity, the pump housing 1 is not described in further detail.

[0113]

[0082] Finally, figures 12 and 13 show various examples of flow conditioners 91a, 91 b that can be used to reduce turbulences in the flow in the 25 volute 31 and thereby improve the results of the flow measurement made by any of the ultrasound flow measurement paths 75, 79, 89 shown in the previous embodiments. In each of figures 12 and 13, the exemplary embodiment of a pump housing 1 is the same as the pump housing 1 already shown in figure 1. Thus, for the sake of brevity, with regard to the

[0114] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026details of the respective pump housing, reference is made to the description of the previous embodiments.

[0115]

[0083] In figure 12 the flow conditioner 91a is formed as an insert that is placed inside the volute 31. The insert 91a is supported by the bottom 5 surface 45 and the inner and outer volute walls 39, 43. The flow conditioner 91a comprises a central flow conditioning element 93a that extends generally parallel to the drive axis 25 and radially about the drive axis 25.

[0116]

[0084] In the exemplary embodiment shown in figure 13, the flow condi10 tioner 91 b is formed by a flow conditioning element 93b that is attached to the volute separator 47. The flow conditioning element 93b also extends generally parallel to the drive axis 25 and radially about the drive axis 25. Attaching the flow conditioning element 93b to the volute separator 47 simplifies the installation of the flow conditioner 91 b as no additional parts need to be mounted in the volute 31.

[0117]

[0085] Figures 14 to 17 show an exemplary embodiment of a pump body 5 that is particularly suitable for a conventional multi-stage centrifugal pump. Figures 14, 16 and 17 only show the pump body 5, whereas in figure 15 a partial, sectional drawing of part of a pump housing 1 is shown.

[0118] 20 Figure 15 depicts the pump body 5 as well as a final impeller stage of the multi-stage impeller and the pump top but does not include the intermediate impeller stages.

[0119]

[0086] The pump body 1 shown in figures 14 to 17 provides an inline configuration where the suction-side inlet 11 and the pressure-side outlet 13 25 are aligned along a common axis that extends perpendicular to the drive axis 25. Contrary to the preceding embodiments, the suction-side inlet 11 and the conduit or duct connecting the suction-side inlet to the central inlet channel 15 and the inlet opening 19 are formed by the pump body 5, i.e., the pump body 5 is not of a modular configuration. Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

[0087] The pump body 5 comprises an axial volute 31 which is aligned along the drive axis 25 on the other side of the inlet opening 19 as the pump chamber (not shown in figures 14, 16 and 17). As can be seen best in figures 14 and 16, the volute 31 is a symmetrical volute 31, i.e., the cross- 5 sectional area of the volute is symmetrical with regard to a plane extending through the drive axis 25 and perpendicular to the plane in which the cut shown in figure 16 was made.

[0120]

[0088] The volute 31 is intended for centrifugal pump where the pressurized flow of pump fluid exiting the pump chamber does not have a rota10 tional component but rather flows primarily parallel to the drive axis 25 through the flow channel 51 towards the volute 31. As can be seen in figure 15, the pump housing 1 formed using the pump body 5 shown in figures 14 to 17 includes final impeller 3b. Contrary to the final impeller 3b shown in figure 2, this impeller 3b is surrounded by an impeller housing 59. The impeller housing 59 is similar or identical to the impeller housing 59 used to encapsulate all preceding impeller stages. Hence, contrary to the exemplary embodiment shown in figures 1 and 2, the rotating flow created by the final stage impeller 3b is not immediately redirected towards the volute 31. Instead guide surfaces 94 and guide vanes 61 are 20 used to redirect the outgoing flow from the impeller first away from the volute 31 and towards the drive axis 25. This aims to reduce the rotational components of the flow so that mainly a linear flow remains which is then redirected by the guide surface 43 of the pump top 7 towards the axial volute 31.

[0121]

[0089] The pump body 5 shown in figures 14 to 17 also comprises a flow measurement path 75 extending between a first ultrasonic transducer 73a and a second ultrasonic transducer 73b. The flow measurement path 75 extends across the outlet region 69, where the volute 31 merges into the pressure-side outlet 31 of the pump body 5. The location of the 30 flow measurement path 75 in the outlet region 69 has been chosen as it covers a particularly wide distance across the volute 31. Further, the flow Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026measurement path 75 is tilted relative to the drive axis 25 to further extend the length of the flow measurement path 75 and thereby improve the accuracy of the flow measurement.

[0122]

[0090] Figures 18 and 1 schematically depict an alternative use of re5 flective surfaces 81 in flow measurement paths 75, 79 located in a volute 31 of a pump body 5. In figures 18 and 19 no details of the pump body 5 are shown that are not required for the understanding of the subsequent description of the alternative use of reflective surfaces 81. It is understood that the flow measurement paths 75, 79 discussed below can be used in 10 any of the above exemplary embodiments provided that these are modified accordingly. This includes, in particular, the use of additional reflective surfaces 81 along the flow measurement path as in the embodiments shown in Figures 6 to 11 is possible in combination with reflective surfaces 81, 81a, 81b that are arranged directly adjacent to the ultrasonic transducers 73a, 73b, 73c, 73d.

[0123]

[0091] In figures 18 and 19, each of the two ultrasonics transducers 73a, 73b, 73c, 73d is associated with a respective reflective surface 81, 81a, 81b in its direct vicinity. However, it is also possible that only one of the ultrasonics transducers 73a, 73b, 73c, 73d is associated with a directly 20 adjacent reflective surface 81, 81a, 81 b, while the other ultrasonic transducer is not associated with a directly adjacent reflective surface 81, 81 a, 81 b as in the preceding embodiment.

[0124]

[0092] Here, the reflective surfaces 81 are used in addition to extending the length of the flow measurement paths 75, 79 also to facilitate or simplify the installation of the ultrasonic transducers 73a, 73b into the pump body 5. To this end, the reflective surfaces 81 are each placed directly adjacent to one of the ultrasonic transducers 73a, 73b, i.e., a first reflective surface 81 a is installed adjacent to the first ultrasonic transducer 73a and the second reflective surface 81 b is installed directly adjacent to the 30 second ultrasonic transducer 73b. The first and second reflective surface Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 202681a, 81b thus primarily serve to redirect the ultrasound emitted by the associated ultrasonic transducer 73a, 73b onto the actual measurement path 75, 79 and to redirect the ultrasound from the measurement path 75, 79 to the associated transducer 73a, 73b after the ultrasound has 5 travelled along the flow measurement path 75, 79. In other words, between each of the transducers 73a, 73b and the respective associated reflective surface 81a, 81 b a feed section 95 of the flow measurement path 75, 79 is formed.

[0125]

[0093] In the exemplary embodiment shown in figure 18, the reflective 10 surfaces 81a, 81b are formed as inserts 97 that are placed or installed in dedicated bores 99 in the pump body 5. In the exemplary embodiment shown in figure 19, the first reflective surface 81a is placed as an insert 101 in the bore 71a. The bore 71a also receives the first ultrasonic transducer 73a. The second reflective surface 81 b is formed directly by the pump body 5.

[0126]

[0094] In all of the embodiments previously described, the ultrasonic transducers that are used may, for example, have excitation frequencies in the range of 1 to 8 MHz. The diameter of the piezoelectric disc including encapsulation from the figure between 6 and 20mm. It is noted that 20 the positions for the ultrasonic transducers described with regard to the previous embodiments can be used for a thorough time-of-flight flow measurement as well as the measurement method such as the Doppler method.

[0127] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026Reference numerals

[0128] 1 pump housing

[0129] 3, 3a, 3b impeller

[0130] 5 pump body

[0131] 5 7 pump top

[0132] 9 motor stool

[0133] 11 suction-side inlet

[0134] 13 pressure-side outlet

[0135] 15 inlet adapter

[0136] 10 17 central inlet channel

[0137] 19 inlet opening

[0138] 21 pump chamber

[0139] 23 drive shaft

[0140] 25 drive axis

[0141] 15 27 impeller inlet

[0142] 29 circumferential outlet

[0143] 31 volute

[0144] 33 outer guide surface

[0145] 34 inner guide surface

[0146] 20 35 guide vanes

[0147] 37 narrowing wall

[0148] 39 inner volute wall

[0149] 41 tubular wall

[0150] 43 outer volute wall

[0151] 25 45 bottom surface

[0152] 47 volute separator

[0153] 49 upper volute wall

[0154] 51 flow channel

[0155] 53 outer wall

[0156] 30 55 inner cylindrical surface

[0157] 57 outer cylindrical surface

[0158] 59 impeller chamber

[0159] 61 guide vanes

[0160] 63 sleeve

[0161] 35 65 housing

[0162] 67 inlet region

[0163] 69 outlet region

[0164] 71a to 71 d bore

[0165] 73a to 73d ultrasonic transducers

[0166] 40 74a, 74b flow sensor

[0167] 75 first ultrasonic flow measurement path 77 tub

[0168] 78 vertical axis

[0169] 79 second ultrasonic flow measurement path

[0170] 45 81 reflective surface

[0171] 81a first reflective surface

[0172] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 202681 b second reflective surface

[0173] 83 reflection angle

[0174] 85 reflective surface

[0175] 87 attached reflective element

[0176] 5 89 indirect ultrasonic flow measurement path 91a, 91b flow conditioner

[0177] 93a, 93b flow conditioning element

[0178] 95 feed section

[0179] 97 insert

[0180] 10 99 bore

[0181] 101 insert

[0182] Patentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

Claims

36 / 42Claims1. A pump housing ( 1 ) for a centrifugal pump with a pump body (5), wherein the pump body (5) partially surrounds a pump chamber (21) accommodating one or more impellers (3) rotatable about a 5 drive axis (25) and defines an inlet opening (19) for pump fluid, a pressure-side outlet (13) for pump fluid as well as a volute (31) for channeling a flow of pump fluid generated in the pump chamber (21) towards the pressure-side outlet (13),wherein each impeller (3) of the one or more impellers (3) comprises an axial inlet aligned with the drive axis (25) and a circumferential outlet (29),wherein the volute (31 ) is formed along the drive axis (25) on a same side of any circumferential outlet (29) of the one or more impellers (3) as the inlet opening (19) of the pump body (5), and 15 wherein the pump body (5) comprises an ultrasonic flow measurement path (75) defined between a first ultrasonic transducer (73a; 73c) and a second ultrasonic transducer (73b; 73c), wherein the ultrasonic flow measurement path (75) extends entirely in the volute (31) and does not overlap with any circumferential outlet (29) of the one or more impellers (3) along the drive axis (25).

2. Pump housing ( 1 ) according to claim 1 , wherein the pump housing (1) is configured for redirecting a flow of pump fluid flowing outwardly away from the drive axis (25) out of the circumferential outlet (29) of one impeller (3) of the one or more impellers (3) into a flow 25 of pump fluid towards the volute (31 ),wherein the pump housing (1) preferably comprises a pump top (7) with a curved inner surface for redirecting the outwardly flowing flow into a flow of pump fluid flowing towards the volute (31 ), and / oratentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026wherein the pump housing (1) preferably comprises a plurality of guide vanes (35; 61 ) for redirecting the outwardly flowing flow of pump fluid into a rotating flow of pump fluid flowing towards the volute (31 ).5 3. Pump housing (1) according to claim 1 or 2, wherein the pump housing (1) comprises a volute separator (47), wherein the volute separator (47) is located along the drive axis (25) between the one or more impellers (3) and the volute (31) and wherein the volute separator (47) is configured for partially separating the pump chamber (21 ) from the volute (31 ), thereby reducing a radial width of a flow channel (51 ) for pump liquid between the pump chamber (21 ) and the volute (31 ),wherein the volute separator (47) is located along the drive axis (25) between the one or more impellers (3) and the ultrasonic 15 flow measurement path (75).

4. Pump housing ( 1 ) according to claim 3, wherein the volute separator (47) sectionally defines an inner circumferential surface delimiting the flow channel (51 ) between the pump chamber (21 ) and the volute (31 ) towards the drive axis (25),20 wherein the inner circumferential surface extends generally parallel to the drive axis (25) and / or parallel to an outer circumferential surface delimiting the flow channel (51) between the pump chamber (21 ) and the volute (31 ) away from the drive axis (25), or wherein the inner circumferential surface extends on a slope relative to the drive axis (25) such that a distance of the inner circumferential surface from the drive axis (25) decreases towards the volute (31 ).

5. Pump housing (1) according to any of the preceding claims, wherein the pump housing (1) comprises an outer circumferential 30 guide surface extending generally parallel to the drive axis (25) and atentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026delimiting the flow channel (51) between the pump chamber (21) and the volute (31 ) on a side facing away from the drive axis (25), wherein the outer circumferential guide surface is preferably at least partially formed by at least one of a pump top (7) of the 5 pump housing (1), a sleeve (63) extending between the pump top (7) and the pump body (5), and the pump body (5).

6. Pump housing (1) according to any of the preceding claims, wherein a distance of the first ultrasonic transducer (73a; 73c) from each circumferential outlet of the one or more impellers (3) along 10 the drive axis (25) is less than a distance of the second ultrasonic transducer (73b; 73d) from the respective circumferential outlet of the one or more impellers (3) along the drive axis (25).

7. Pump housing (1) according to any of the preceding claims, wherein the ultrasonic flow measurement path (75) is formed as a 15 direct line-of-sight path between the first ultrasonic transducer (73a;73c) and the second ultrasonic transducer (73b; 73d).

8. Pump housing (1) according to any of the preceding claims, wherein the ultrasonic flow measurement path (75) is formed as an indirect path comprising at least one reflective surface (81) on the 20 ultrasonic flow measurement path (75) between the first ultrasonic transducer (73a; 73c) and the second ultrasonic transducer (73b; 73d).

9. Pump (1) housing according to claim 8, wherein the at least one reflective surface (81 ) is part of the pump body (5), or25 wherein the at least one reflective surface (81) is part of the volute separator (47), wherein the volute separator (47)is located along the drive axis (25) between the one or more impellers (3) and is configured for partially separating the pump chamber (21) from the volute (31 ), oratentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026wherein the at least one reflective surface (81) is part of the outer circumferential guide surface extending generally parallel to the drive axis (25) and delimiting the flow channel (51 ) between the pump chamber (21 ) and the volute (31 ) on a side facing away from 5 the drive axis (25).

10. Pump housing (1) according to claim 8 or 9, wherein a reflective surface (81a, 81 b) of the at least one reflective surface (81, 81a, 81b) is located directly adjacent to the first ultrasonic transducer (73a; 73c) or the second ultrasonic transducer (73b, 73c), and wherein preferably the ultrasonic flow measurement path (75) comprises at least two reflective surfaces (81, 81a, 81 b), wherein a first reflective surface (81a) of the at least two reflective surfaces (81, 81 a, 81 b) is located directly adjacent to the first ultrasonic transducer (73a; 73c), a second reflective surface (81 b) of the least two 15 reflective surfaces (81 , 81 a, 81 b) is located directly adjacent to the second ultrasonic transducer (73b; 73d), wherein a distance between the first reflective surface (81a) and the second reflective surface (81b) exceeds the distance between the first ultrasonic transducer (73a, 73c) and the first reflective surface (81) and the distance between the second ultrasonic transducer (73a, 73c) and the second reflective surface (81).

11. Pump housing (1) according to any of the preceding claims, wherein the first ultrasonic transducer (73a; 73c) is located in an outer volute wall (43) delimiting the volute (31 ) on a side facing ra25 dially away from the drive axis (25) or in an inner volute wall (39) delimiting the volute (31 ) towards the drive axis (25), and wherein the second ultrasonic transducer (73b; 73d) is located in the outer volute wall (43) or in the inner volute wall (39).atentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 202612. Pump housing (1) according to any of the preceding claims, wherein the pump housing (1) comprises at least one flow conditioner (91 a to 91 d) located in the volute (31 ).

13. Pump housing (1) according to claim 11, wherein the at least one 5 flow conditioner (91a to 91 d) is formed as an insert placed in the volute (31 ), and / orwherein the at least one flow conditioner (91a to 91 d) is part of the pump body (5), and / orwherein the at least one flow conditioner (91a to 91 d) is part 10 of the volute separator (47), wherein the volute separator (47) is located along the drive axis (25) between the one or more impellers (3) and the volute (31 ) and is configured for partially separating the pump chamber (21 ) from the volute (31 ), and / orwherein the at least one flow conditioner (91a to 91 d) is attached to guide vanes (35; 61 ) formed at a pump top (7), wherein the guide vanes (35; 61) are configured for redirecting a flow of pump fluid flowing out of the circumferential outlet of one of the impellers (3) of the one or more impellers (3) towards the volute (31 ).

14. Pump housing (1) according to claim 11 or 12, wherein the at least 20 one flow conditioner (91 a to 91 d) extends on an arc about the drive axis (25), andwherein the at least one flow conditioner (91a to 91 d) extends perpendicular to the drive axis (25) or parallel to the drive axis (25).

15. Pump housing (1) according to any of the preceding claims, 25 wherein the volute (31 ) is configured to limit a recirculation of pump fluid,wherein the volute (31) preferably extends circumferentially between an inlet region (67) and an outlet region (69) where the volute (31) merges into the pressure-side outlet (13) of the pumpatentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 202641 / 42body (5), wherein a radial width of the volute (31) about the drive axis (25) increases from the inlet region (67) to the outlet region (69).

16. Pump housing ( 1 ) according to claim 14 or 15, wherein a maximum distance of the outer volute wall (43) from the drive axis (25) is con- 5 stant and wherein a distance of the inner volute wall (39) from the drive axis (25) decreases from the inlet region (67) to the outlet region (69).

17. Pump housing ( 1 ) according to claim 14, 15, or 16, wherein the volute (31) comprises a bottom surface (45) delimiting the volute (31) 10 in a direction facing away from the one or more impellers (3), wherein a maximum distance of the bottom surface (45) from the one or more impellers (3) increases from the inlet region (67) to the outlet region (69).atentanwdlte Hemmer Lindfeld Frese GP 3841 WO, 05 / 02 / 2026

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