EP3978760A1 - Submersible centrifugal pump and impeller for same - Google Patents

Abstract

Described is a centrifugal submersible pump (1) with a drive shaft (11), an impeller (13) connected non-rotatably to the drive shaft (11), an impeller housing (5) and a seat (6) for fastening the centrifugal submersible pump (1) in such a way at the top on a liquid container (8), that the drive shaft (11) extends from top to bottom into the liquid container (8), the impeller housing (5) forming a pump chamber (12) in which the impeller (13) is arranged, the Impeller housing (5) has an annular surface (49) which runs around the drive shaft (11) within the pump chamber (12). According to the invention, the annular surface (49) of the impeller housing (5) inside the pump chamber (12) points outwards, and the impeller (13) has an inwardly pointing annular surface (50) which the annular surface (49) of the Impeller housing (5) surrounds the outside. It is also provided that the impeller (13) has a plurality of main blades (42) on one of its sides and a plurality of additional blades (47) on a side opposite these, and that the impeller (13) has a ring ( 55) with an inwardly pointing annular surface (50), which is arranged on a side of the additional blades (47) facing away from the plate (41) and/or surrounds the additional blades (47) on their outer circumference.

Description

The invention is based on a submersible centrifugal pump with the features specified in the preamble of claim 10 and an impeller intended for this purpose with the features specified in the preamble of claim 1.

Such a submersible centrifugal pump with such an impeller is from DE 35 40 025 A1 famous. This submersible centrifugal pump has a drive motor, a drive shaft and an impeller seated on the drive shaft and a seat for fastening the submersible centrifugal pump to a liquid container at the top in such a way that the drive shaft extends from top to bottom into the liquid container. The impeller is arranged at the lower end of the drive shaft below the surface of a liquid in the liquid container, specifically in an impeller housing forming a pump chamber. The impeller has a disk which has several main vanes on its underside for pumping the liquid as the impeller rotates in the pump chamber.

From the DE 33 28 484 A1 a submersible centrifugal pump is known in which the drive shaft is surrounded by an inner tube which extends upwards from an impeller casing. The inner tube is surrounded by an outer tube which, together with the inner tube, forms an annular riser channel for the liquid to be pumped. In the area of the lower end of the outer tube, two transverse lines run through the inner tube, the riser channel and the outer tube, which connect a space inside the inner tube with a space outside the outer tube. The impeller housing forms a pump chamber in which an impeller is arranged. The annular riser channel is completely open at its lower end to the pump chamber.

From the DE 32 14 185 A1 Furthermore, a submersible centrifugal pump is known which has a plurality of risers which each have the shape of an annular section in cross section, the annular sections of the risers running around the drive shaft. Slots are arranged between the riser tubes, which connect a space surrounding the drive shaft with a space outside the riser tubes and extend essentially over the entire length of the riser tubes.

The object of the invention is to improve a submersible centrifugal pump and an impeller of the type mentioned at the outset with regard to the flow occurring in the pump chamber.

This object is achieved by an impeller having the features specified in claim 1 and a submersible centrifugal pump having the features specified in claim 10. Advantageous developments of the invention are the subject matter of the dependent claims.

A submersible centrifugal pump according to the invention has a drive shaft, an impeller which is non-rotatably connected to the drive shaft, and an impeller housing. The impeller housing forms a pump chamber in which the impeller is arranged. The submersible centrifugal pump has a seat for fastening the Submersible centrifugal pump at the top of a liquid container in such a way that the drive shaft extends from top to bottom into the liquid container. The submersible centrifugal pump can be fastened with its seat on an upper container wall of the liquid container. In operation, the impeller comes to lie inside the liquid container below the surface of a liquid contained therein. The impeller housing has an annular surface, in particular a cylinder jacket surface, which runs around the drive shaft within the pump chamber, in particular coaxially thereto. The annular surface of the impeller housing inside the pump chamber faces outwards. The impeller has, in particular in the area of its outer circumference, an inwardly pointing annular surface, in particular a cylinder jacket surface, which surrounds the annular surface of the impeller housing on the outside.

The impeller according to the invention has a plate which has a plurality of main blades on one of its sides and a plurality of additional blades on a side opposite the main blades. The main blades serve to actually pump the liquid. The auxiliary blades can be located on the side of the impeller facing the seating surface, which is its side facing upwards in operation. The impeller can have a hub with which it can be attached to the drive shaft, in particular to one of its ends. The plate may extend outwardly from the driveshaft or hub. The disk can extend radially between a small circumference and a large circumference on the impeller. The plate can run transversely or at an angle to the drive shaft, i.e. it can be flat or conical. The main blades extend along the disk from a small perimeter to a large perimeter of the impeller. In particular, the main blades have a curvature that can be seen in a view along the drive shaft. The main vanes and the auxiliary vanes extend along the disk on opposite sides and are connected to it, respectively. Each of the main blades and each of the auxiliary blades extends away from the disk by a predefined height. The impeller has on the outer circumference of the additional blades on a ring with an inwardly directed annular surface, which faces away from the plate on a side of the Additional blades is arranged and / or surrounds the additional blades on its outer periphery. The annular surface can in particular point towards the hub.

Both the features of the impeller according to the invention specified in claim 1 and the features of the submersible centrifugal pump according to the invention specified in claim 10 alone already achieve an improvement in the flow conditions of the liquid in the pump chamber. The flow in the pump chamber can be improved particularly significantly by combining the impeller according to the invention with the submersible centrifugal pump according to the invention. In particular, the improved flow in the pump chamber has a self-centering effect on the impeller. The flow forces arising from the rotation of the impeller during operation can thus contribute to the centering of the impeller in the impeller housing, so that the radial forces transmitted from the impeller to the drive shaft are lower. The load on the drive shaft bearing resulting from the flow forces can be greatly reduced as a result. This can increase the service life of the submersible centrifugal pump. In addition, there is no need for the drive shaft to be mounted inside the liquid container.

The annular surface of the impeller housing has a smaller circumference than the annular surface of the impeller. The annular surface of the impeller can surround the annular surface of the impeller housing at a distance such that a gap is formed between the two annular surfaces, which gap runs along the circumference of the impeller. The annular surface of the impeller and the annular surface of the impeller housing can extend coaxially to the drive shaft, in particular over a predefined section. The annular surface of the impeller and the annular surface of the impeller housing can each be designed as a cylindrical surface, in particular as a surface of a circular cylinder, or as a conical surface. Each of the two annular surfaces can be designed without interruption along its circumference.

The drive shaft is led out upwards from the pump chamber through a hole in the top of the impeller housing, in particular in its top wall. Such submersible centrifugal pumps are for pumping aggressive liquids, for example acids or alkalis. Abrasive particles can also be contained in the liquid. For this reason, seals that touch the drive shaft are avoided, so that there is an annular gap between the drive shaft and the impeller housing. If the pressure in the pump chamber is appropriate, a pressure drop can occur at this annular gap. Depending on the operating status of the submersible centrifugal pump, the pressure in the pump chamber can be higher than in the liquid container, so that liquid can escape from the impeller housing through this annular gap in the form of a so-called bypass flow. The bypass flow is a leakage flow that reduces the amount of liquid pumped out of the liquid container by the submersible centrifugal pump. However, operating states of the submersible centrifugal pump can also occur in which the pressure in the pump chamber is lower than in the liquid container, so that liquid can be sucked in through the annular gap between the drive shaft and the impeller housing. Such suction can be undesirable when the liquid level in the liquid container is low, so that there is a risk of air being sucked into the pump chamber through this annular gap. In the case of foam-forming liquids in particular, this can be very disadvantageous. Because, according to the invention, the annular surface of the impeller and the annular surface of the impeller housing are opposite one another, this pressure drop can be reduced over a wide operating range of the submersible centrifugal pump. This applies in particular in combination with the additional blades, which during operation ensure pressure equalization at the gap between the annular surface of the impeller and the annular surface of the impeller housing, and can thus lead to a significant reduction in the pressure drop. As a result, both a bypass flow and a suction of liquid through the annular gap between the drive shaft and the impeller housing can be avoided over a wide operating range of the submersible centrifugal pump.

In a further aspect of the invention, the impeller shell may have a top wall with a downwardly facing surface that extends along the top of the impeller. The surface on the top wall may abut the annular surface of the impeller shell. The surface on the upper wall of the impeller housing can in particular extend parallel or equidistant to the side of the additional blades facing away from the plate. This will the bypass flow is further reduced. The additional blades can run radially in a straight line from the inside to the outside.

In a further embodiment, the ring of the impeller can touch the additional blades on their outer circumference or surround them at a distance. The impeller can have a cover on a side of the main blades facing away from the plate. The cover may extend outwardly beyond the outer perimeter of the disk and/or the outer perimeter of the main vanes. The main vanes can extend beyond the outer periphery of the disk. Between two of the main vanes, the disk and the cover, an inside-out channel is formed which is closed along its entire circumference. Due to the rotation of the impeller, liquid is conveyed radially outwards through this channel of the impeller during operation. The cover can have a hole in its center, ie coaxially with the hub or drive shaft, the circumference of which is larger than the inner circumference of the main blades. A suction tube can be connected to the inner circumference of the cover, which extends from the cover to the side facing away from the plate.

In a further embodiment, the impeller can have two rings. A first of the rings can be arranged on a side of the additional blades facing away from the disk and/or surround the additional blades on their outer circumference. A second of the rings may encircle the disk at a spacing and/or the main vanes at their outer perimeter. The first ring may include the inboard annular surface surrounding the outboard annular surface of the impeller shell. The second ring can extend coaxially to the drive shaft, in particular over a predefined section. The second ring can be located on the side of the main blades facing the additional blades. The second ring can also surround the additional blades and/or the first ring at a distance. Each of the rings can have a cylinder jacket surface, in particular a jacket surface of a circular cylinder, on its inner circumference and/or on its outer circumference. The second ring can deflect the liquid conveyed radially outwards by the main vanes into a liquid along the drive shaft improve flow direction. As a result, the efficiency of the submersible centrifugal pump can be improved.

The impeller can be made in one piece or in several parts. Each component of the impeller, in particular the hub, the disk, the main blades, the additional blades, the cover and the at least one ring, can all or only partially be manufactured in one piece with one another or in multiple parts. In particular, the first ring and/or second ring can be designed in the form of a pipe section which is attached to the impeller, in particular welded to it.

In a further embodiment of the invention, the drive shaft can be surrounded by an inner tube. The drive shaft and the inner tube can be surrounded by an outer tube. The outer tube and the inner tube each extend between the impeller shell and the seat. An inner surface of the outer tube forms an annular riser channel for the liquid to be pumped with an outer surface of the inner tube. The inner pipe and the outer pipe thus form a double-walled riser pipe, between the walls of which the annular riser channel is formed. Several transverse lines run through the inner pipe, the riser channel and the outer pipe, each of which connects a space inside the inner pipe with a space outside the outer pipe. Such transverse lines and their function are known to those skilled in the art, for example from DE 33 28 484 A1 . The outer tube and the inner tube can each be connected, in particular welded, to the upper wall of the impeller housing. In the upper wall of the impeller housing, several channels are arranged, through which the pump chamber is connected to the riser channel. The liquid to be pumped can enter the riser channel from the pump chamber through these channels. Each of the channels has a longitudinal extension from the pump chamber to the riser channel and an opening into the riser channel. At its mouth in the riser channel, each channel specifies a direction of flow, which leads along the inner surface of the outer tube between two of the transverse lines. The predetermined direction of flow and / or the longitudinal direction of each channel can obliquely to the longitudinal direction of the outer tube or the drive shaft oriented. The specified direction of flow can be skew to the drive shaft. Two lines that do not run parallel to each other in space and do not intersect are referred to as skewed. Each of the channels can in particular have the shape of a helical section. The continuation of the spiral section passes between two of the transverse lines.

The described arrangement of the inlet channels in the upper wall of the impeller housing directs the liquid to be pumped into the riser channel in a targeted manner. The flow can thus be directed between two transverse lines. As a result, each of the transverse lines is to a certain extent in the flow shadow of the main flow, which enters the riser channel through the channels from the pump chamber. Uncontrolled turbulence in the riser channel, which causes heavy losses, can be significantly reduced in this way. In contrast to the one from the DE 33 28 484 A1 known configuration, in which the liquid entering the annular riser channel hits the transverse lines in an uncontrolled manner, flow losses can be reduced and the efficiency of the submersible centrifugal pump can be increased.

In a further embodiment, the mouth of each of the channels can be offset along the circumference to the transverse lines. The center of each orifice is at a different circumferential position than the center of each transverse line. The channels may be circumferentially equally spaced. All channels can have the same shape. Each of the transverse lines can be formed by a transverse tube which is attached, in particular welded, to the inner tube and the outer tube and extends through the riser channel. The inner tube and the outer tube each have a hole for this purpose. Several of the transverse lines can lie in a plane running transversely, in particular at right angles, to the drive shaft. A first level with several transverse lines can be arranged in the area of the lower end of the outer tube. In operation, the transverse lines arranged in the first level are below the surface of the liquid in the liquid container. The number of transverse lines arranged in the first level can, in particular, be related to the number of transverse lines in the upper wall of the impeller housing arranged channels match. A second level with several transverse lines can be arranged above the first level, which is located in particular above the surface of the liquid in the liquid container. The second level can be arranged in the area of the upper end of the outer tube. The number of cross lines in the first level and in the second level can match. The transverse lines in the two planes can be arranged one behind the other when viewed along the drive shaft.

In another embodiment, the channels may be located in the top wall of the impeller shell on a median perimeter of the top wall that is greater than the outer perimeter of the first ring and smaller than the inner perimeter of the second ring, particularly with the median perimeter between the two rings. As a result, the liquid coming from the impeller can advantageously flow into the channels in the upper wall of the impeller housing and the efficiency of the submersible centrifugal pump can be further improved.

In a further embodiment, the bearing of the drive shaft can be arranged above the seat surface for fastening the submersible centrifugal pump. The drive shaft can be mounted exclusively on the side of the seat facing away from the impeller housing. As a result, all bearings for the drive shaft are located outside of the liquid container and do not come into contact with the liquid to be pumped. Due to the self-centering effect of the flow in the pump chamber on the impeller, submersible centrifugal pumps according to the invention can extend very far down into the liquid container without the drive shaft having to be supported within the liquid container or below the surface of the liquid. The running wheel can have a distance of more than 500 mm, in particular 600 mm to 800 mm, from the seat surface. The bearing can consist of a single bearing, in particular ball bearings, or of more than one bearing. The bearing play in the bearing of the drive shaft can be dimensioned in such a way that the impeller does not come into contact with the impeller housing either during operation or when not in use. This ensures that the centrifugal submersible pump according to the invention can run dry over the long term.

In a further embodiment, the drive shaft of the submersible centrifugal pump can be coupled to a drive, for example via a clutch or a drive belt. The submersible centrifugal pump can also contain a drive motor coupled to the drive shaft, which is arranged on the side of the seat surface facing away from the impeller housing. As a result, the drive is arranged outside the liquid container during operation. The seat can be on the drive motor or on a mounting flange. The inner tube and the outer tube may each extend from the mounting flange to the impeller shell. As a result, the impeller housing is carried by the inner tube or the outer tube. The mounting flange can have a pressure nozzle connection, which is located on the side of the seat surface facing away from the impeller housing, that is to say outside of the liquid container during operation. The installation flange is used to guide the liquid to be pumped through the upper tank wall. The riser channel is connected to the pressure nozzle connection via the installation flange. The drive shaft can be mounted exclusively in the drive motor with two bearings, the impeller being fastened to the end of the drive shaft facing away from the drive motor. The impeller is arranged at the free end of the drive shaft ("overhung storage").

Figur 1

eine Seitenansicht einer erfindungsgemäßen Tauchkreiselpumpe,

Figur 2

einen Längsschnitt der Tauchkreiselpumpe der Figur 1,

Figur 3

eine vergrößerte Ansicht des unteren Endes der Tauchkreiselpumpe der Figur 2,

Figur 4

einen Querschnitt durch die Tauchkreiselpumpe entlang der Schnittfläche IV-IV der Figur 1,

Figur 5

einen Querschnitt durch die Tauchkreiselpumpe entlang der Schnittfläche V-V der Figur 1,

Figur 6

eine perspektivische Ansicht auf das untere Ende der Tauchkreiselpumpe der Figur 1 bei abgenommenem Außenrohr,

Figur 7

eine schematische Ansicht zur Verdeutlichung der Strömung im unteren Bereich der Tauchkreiselpumpe,

Figur 8

eine perspektivische Ansicht eines erfindungsgemäßen Laufrades,

Figur 9

das Laufrad der Figur 8 in einer Ansicht von oben,

Figur 10

das Laufrad der Figur 8 in einer Ansicht von unten,

Figur 11

eine perspektivische Ansicht einer Variante eines erfindungsgemäßen Laufrades,

Figur 12

eine Variante einer erfindungsgemäßen Tauchkreiselpumpe in einer Darstelllung entsprechend der Figur 2,

Figur 13

eine weitere Variante einer erfindungsgemäßen Tauchkreiselpumpe in einer Darstelllung entsprechend der Figur 2.

Further details and advantages of the invention are explained using exemplary embodiments of the invention with reference to the accompanying drawings. Identical and corresponding components are provided therein with the same reference numbers. Show it:

figure 1

a side view of a submersible centrifugal pump according to the invention,

figure 2

a longitudinal section of the submersible centrifugal pump figure 1 ,

figure 3

an enlarged view of the lower end of the submersible centrifugal pump figure 2 ,

figure 4

a cross section through the submersible centrifugal pump along the interface IV-IV of figure 1 ,

figure 5

a cross section through the submersible centrifugal pump along the sectional area VV of figure 1 ,

figure 6

a perspective view of the lower end of the submersible centrifugal pump figure 1 with the outer tube removed,

figure 7

a schematic view to illustrate the flow in the lower area of the submersible centrifugal pump,

figure 8

a perspective view of an impeller according to the invention,

figure 9

the impeller of figure 8 in a view from above,

figure 10

the impeller of figure 8 in a bottom view,

figure 11

a perspective view of a variant of an impeller according to the invention,

figure 12

a variant of a submersible centrifugal pump according to the invention in a representation corresponding to figure 2 ,

figure 13

another variant of a submersible centrifugal pump according to the invention in a representation corresponding to figure 2 .

A submersible centrifugal pump 1 according to the invention contains a mounting flange 3, an outer tube 4 and an impeller housing 5. The mounting flange 3 has a seat 6 with which the submersible centrifugal pump 1 is fastened to an upper container wall 7 of a liquid container 8. In the liquid container 8 there is a liquid 9 to be pumped. The level of the liquid 9 is in figure 1 indicated by its surface 10. The outer tube 4 extends from the mounting flange 3 to the impeller housing 5.

The submersible centrifugal pump 1 according to the invention has a drive shaft 11, see figures 2 , 12 and 13 , which extends from the impeller housing 5 to the side of the seat surface 6 facing away from the impeller housing 5 and can be designed in one or more parts. The submersible centrifugal pump 1 can contain an electric drive motor 2, see figure 2 , or can be driven by an external drive, see figures 12 and 13 .

At the in figure 2 In the submersible centrifugal pump 1 shown, the drive shaft 11 extends from the impeller housing 5 into the drive motor 2. Two bearings 60 and 61 are arranged in the drive motor 2, in which the drive shaft 11 is overhung.

The impeller housing 5 of a submersible centrifugal pump 1 according to the invention forms a pump chamber 12 in its interior, in which an impeller 13 is arranged. The impeller 13 is fixed in a torque-proof manner on the lower end of the overhung drive shaft 11 . The submersible centrifugal pump 1 has an inlet 14 at its lower end and an outlet 15 on the mounting flange 3. With its rotating impeller 13, the submersible centrifugal pump 1 conveys the liquid 9 from the inlet 14 to the outlet 15. The outlet 15 is designed as a pressure nozzle connection 16, via which a pipeline, not shown, can be connected to the submersible centrifugal pump 1 in order to direct the pumped liquid 9 to the desired location. The outlet 15 and the pressure nozzle connection 16 are located outside of the liquid container 8. An inner tube 17, which surrounds the drive shaft 11, is arranged inside the outer tube 4. The inner tube 17 forms, together with the outer tube 4, an annular riser channel 18 for the liquid 9 to be pumped. The impeller housing 5 has an upper wall 19 which delimits the pump chamber 12 from the riser channel 18 . The wall 5 and the installation flange 3 are connected, in particular welded, both to the inner tube 17 and to the outer tube 4 . The impeller housing 5, the inner tube 17, the outer tube 4 and the impeller 13 consist of a material which is resistant to aggressive acids and/or alkalis, for example corrosion-resistant stainless steel or a suitable plastic. At its upper end, the riser channel 18 opens into a collection space 20 which is located in the mounting flange 3 and directs the liquid to the outlet 15 . On its side opposite the pressure nozzle connection 16, the collecting chamber 20 has a smaller flow cross section, which increases towards the pressure nozzle connection 16, see FIG figure 2 . In the upper wall 19 four channels 21 are arranged, through which the pump chamber 12 is in communication with the riser channel 18 . The channels 21 are distributed evenly along the circumference, see in particular figure 4 . As a result, the forces acting in the pump chamber 12 on the impeller 13 along the circumference are almost eliminated, so that even a very long drive shaft 11 can be overhung on the side of the seat 6 facing away from the impeller housing 5 without excessive lateral forces being exerted on the lower end of the Drive shaft 11 act.

The submersible centrifugal pump 1 contains eight transverse lines 22 which run through the inner tube 17, the riser channel 18 and the outer tube 4 and each connect a space 23 inside the inner tube 17 with a space 24 outside the outer tube 4. Each of the transverse lines 22 is formed by a transverse tube 25 which is welded to the inner tube 17 and the outer tube 4 . For each transverse line 22, both the inner tube 17 and the outer tube 4 have a hole. Each transverse tube 25 extends through the riser channel 18, with no liquid being able to flow from the transverse line 22 into the riser channel 18 or vice versa. In a manner known per se, the transverse lines 22 prevent the liquid 9 in the inner space 23 from rising up to the mounting flange 3 or even up to the bearing 60 . Four transverse lines 22 lie in a first plane 26, which is located in the region of the lower end of the outer tube 4 below the surface 10, see figures 1 and 4 . Four further transverse lines 22 are arranged in a second level 27 which is arranged above the surface 10 in the region of the upper end of the outer tube 4 . The two planes 26 and 27 are perpendicular to the drive shaft 11.

Each of the channels 21 extends along a longitudinal extension from the pump chamber 12 to the riser channel 18 which is formed between the inner surface 30 of the outer pipe 4 and the outer surface 31 of the inner pipe 17 . Each of the channels 21 has a mouth 28 with which the channel 21 opens into the riser channel 18 . The mouth 28 is designed in such a way that it specifies a direction of flow 29 which runs along the inner surface 30 of the outer tube 4 between two transverse lines 22 . The flow entering the riser channel 18 is thereby guided through between the transverse lines 22 . The direction of flow 29 is oriented obliquely to the longitudinal direction of the outer tube 4 . Each channel 22 has the shape of a spiral section, so that the direction of flow 29 has the shape of a spiral, which in figure 6 is indicated by dashed lines. The flow is guided helically between two transverse lines 22 by the direction of flow 29 . As a result, the flow resistance generated by the transverse lines 22 in the riser channel 18 is minimized. In the schematic representation of figure 7 is the top wall 19 of the impeller shell 5 along a circle passing through the channels 21 cut and unfolded in the drawing plane. This makes it clear that each channel 21 specifies a flow direction 29 at its mouth 28 in the riser channel 18 , which leads through between two transverse lines 22 . Because the inner surface 30 of the outer tube 4 is a cylindrical surface, the flow emerging from the openings 28 in the direction of flow 29 is deflected helically at the curved inner surface 30 and guided between two transverse lines 22, cf. figure 6 . The mouths 28 are each offset from the transverse lines 22, see in particular figure 4 . The transverse lines 22 are thus arranged in the flow shadow of the flow emerging from the orifices 28 .

The impeller 13 includes a hub 40 and a disc 41, see in particular Figures 8 to 11 . The plate 41 extends transversely to the drive shaft 11 from the hub 40 radially outwards. In the variant shown, the plate 41 is flat. However, it can also extend conically outwards in a manner that is not shown. On the underside of the plate 41 four main blades 42 are arranged, which run curved from the inside to the outside, see in particular figures 9 , 10 and 11 . A cover 43 , which extends along the plate 41 , is arranged on a side of the main blades 42 which is remote from the plate 41 . The cover 43 has a hole 44 in its center, the circumference of which is larger than the inner circumference of the main blades 42, cf figure 10 . A suction tube 45 connects to the inner circumference of the cover 43 and extends on the side facing away from the plate 41 to a suction strainer 46 at the inlet 14 . The cover 43 extends outwardly beyond the outer periphery of the disk 41 and the outer periphery of the main blades 42, see FIG Figure 8, 9 and 11 .

Four additional blades 47 running in a straight line from the inside to the outside are arranged on the upper side of the plate 41 . The impeller housing 5 has on the underside of its upper wall 19 a surface 48 which extends parallel to the side of the additional blades 47 facing away from the plate 41 . The impeller housing 5 also has a circular-cylindrical annular surface 49 lying within the pump chamber 12, which faces outwards and around the Drive shaft 11 runs around. In the area of its outer circumference, the impeller 13 has a circular-cylindrical annular surface 50 which faces inwards and surrounds the annular surface 49 at a distance on the outside. A gap 51 is thereby formed between the annular surfaces 49 and 50 . As a result, the flow conditions in the pump chamber 12 are improved and the radial forces on the drive shaft 11 are reduced. The drive shaft 11 is led out of the pump chamber 12 through a hole 52 in the top wall 19 . The upper wall 19 surrounds the drive shaft 11 with a gap 53. During operation of the submersible centrifugal pump 1, liquid 9 is conveyed into the gap 51 by the additional blades 47. As a result, a bypass flow is reduced overall, which flows out of the impeller housing 5 through the gap 53 and flows back unused via the space 23 and the transverse lines 22 into the liquid container 8 . On the outer circumference of the additional blades 47, the impeller 13 has a first ring 55, on which the annular surface 50 is formed. The annular surface 50 surrounds the additional blades 47 on its outer circumference and extends on the side of the additional blades 47 facing away from the plate 41 over a predefined section A along the drive shaft 11. The ring 55 also has a lateral surface of a circular cylinder on its outside. Alternatively, the annular surfaces 49 and 50 can also extend in the form of lateral surfaces of a cone along the drive shaft 11 and form the gap 51 in a manner that is not shown. The upper side of the additional blades 47 and the surface 48 lying opposite thereto can also have the shape of cone surfaces in a manner that is not shown.

The impeller 13 has a second ring 56 which surrounds the main blades 42 on their outer circumference. The second ring 56 also surrounds the plate 41 and the first ring 55 at a distance. The channels 21 in the wall 19 are distributed over a central circumference 57 of the wall 19 which is smaller than the inner circumference of the ring 56, cf Figures 3 and 4 . The ring 56 serves to deflect the liquid 9 conveyed by the main blades 42 in the direction of the channels 21 and can thereby improve the efficiency of the submersible centrifugal pump 1 . The impeller 13 can also be designed without the second ring 56, see FIG figure 11 .

The impeller 13 is designed in several parts. The plate 41 and the additional blades 47 are formed in one piece. The plate 41 is placed on the hub 40. The rings 55 and 56 each have the shape of a pipe section. The ring 55 is attached to the plate 41. The cover 43, the suction tube 45 and the main blades 42 are made in one piece with each other. The ring 56 is attached to the lid 43 . The components of the impeller 13 are welded together.

The in the figures 12 and 13 The submersible centrifugal pumps 1 shown differ from those in figure 2 Submersible centrifugal pump shown in the manner in which the drive shaft 11 is mounted and driven. Otherwise, the submersible centrifugal pumps 1 of the figures 12 and 13 identical to the submersible centrifugal pump 1 of figure 2 formed, in particular in the projecting into the liquid container 8 in the region below the seat 6, so that to avoid repetitions in this respect, reference is made to the above description. The submersible centrifugal pumps 1 of figures 12 and 13 do not contain a drive motor 2; instead, the drive shaft 11 is led out of the submersible centrifugal pump 1 on the side of the seat surface 6 opposite the impeller housing 5. The drive shaft 11 can be coupled to an external drive via this end 65 protruding from the submersible centrifugal pump 1, for example via a clutch or belt pulley (not shown). This can be advantageous if the drive is arranged at a greater distance from the submersible centrifugal pump 1, for example if the submersible centrifugal pump 1 is in a potentially explosive area and the drive is arranged outside of this area. At the in figure 12 Submersible centrifugal pump 1 shown sits on the mounting flange 3, a bearing housing 66, which contains two bearings 60 and 61, in which the drive shaft 11 is mounted. At the in figure 13 Submersible centrifugal pump 1 shown, the drive shaft 11 is mounted with only a single bearing 60, in particular a deep groove ball bearing. Here, too, the bearing 60 is seated in a bearing housing 66 which is connected to the mounting flange 3 .

All bearings 60, 61 of the drive shaft 11 are located outside of the liquid container 8. No further bearings are required for the drive shaft 11, in particular no bearings inside the liquid container 8 which would be exposed to the attack of the aggressive liquid 9. The stability of the submersible centrifugal pump 1 can be extended as a result, especially when running dry when there is no longer any liquid 9 in the impeller housing 5 .

The bearing play in the bearings 60, 61 is dimensioned in all variants of the submersible centrifugal pump 1 so that the impeller 13 does not touch the impeller housing 5. In particular, due to the improved flow conditions in the pump chamber 12 according to the present invention, the cost of mounting the drive shaft 11 can be reduced and even a design with a very large distance between the impeller 13 and the seat 6 of more than 500 mm or according to figure 13 be realized with only a single bearing 60. <b>Reference List</b> 1 submersible centrifugal pump 41 Plate 2 drive motor 42 main blades 3 mounting flange 43 lid 4 outer tube 44 hole in 43 5 impeller housing 45 intake manifold 6 seat 46 strainer 7 container wall 47 extra blades 8th liquid container 48 surface at 19 9 liquid 49 Ring surface at 5 10 surface 50 Ring surface at 13 11 drive shaft 51 Gap between 49 and 50 12 pump room 52 hole in 19 13 Wheel 53 Gap between 11 and 19 14 inlet 55 first ring 15 outlet 56 second ring 16 pressure port connection 57 medium girth 17 inner tube 60 warehouse 18 riser channel 61 warehouse 19 top wall of 5 65 end of the drive shaft 20 collection room 66 bearing housing 21 channels 22 cross lines A section 23 space within 17 24 space outside 4 25 cross tube 26 first floor 27 second level 28 mouth 29 flow direction 30 inner surface of 4 31 Outer surface of 17 40 hub

Claims (15)

Impeller (13) for attachment to a drive shaft (11) of a submersible centrifugal pump (1) with a plate (41) which has several main blades (42) on one of its sides, characterized in that that the impeller (13) has a plurality of additional blades (47) on a side opposite the main blades (42), and that the impeller (13) has a ring (55) on the outer circumference of the additional blades (47) with an inwardly pointing annular surface (50) which is arranged on a side of the additional blades (47) facing away from the disk (41) and/or surrounds the additional blades (47) on its outer circumference. An impeller as claimed in claim 1, in which the ring (55) touches or spacedly surrounds the auxiliary vanes (47) at their outer periphery. An impeller according to claim 1 or 2, comprising two rings (55, 56), a first of the rings (55) having the inwardly facing annular surface (50) according to claim 1, and a second of the rings (56) having the plate ( 41) at a distance and/or surrounds the main blades (42) at their outer periphery. An impeller as claimed in claim 3, in which the second ring (56) surrounds the auxiliary vanes (47) and/or the first ring (55) at a distance. An impeller as claimed in any preceding claim, in which the main vanes (42) extend beyond the outer periphery of the disc (41). Impeller according to one of the preceding claims, which has a cover (43) on a side of the main blades (42) remote from the disk (41). An impeller according to claim 6, wherein the cover (43) has a hole (52) at its center, the circumference of which is larger than the inner circumference of the main blades (42). Impeller according to Claim 6 or 7, in which a suction pipe (45) is connected to the inner circumference of the cover (43) and extends to the side of the cover (43) remote from the disk (41). An impeller according to any one of claims 6 to 8, in which the cover (43) extends outwardly beyond the outer periphery of the disk (41) and/or the outer periphery of the main blades (42). Submersible centrifugal pump (1) with a drive shaft (11), an impeller (13) connected non-rotatably to the drive shaft (11), an impeller housing (5) and a seat (6) for fastening the submersible centrifugal pump (1) to a liquid container (8 ) that the drive shaft (11) extends from top to bottom into the liquid container (8), the impeller housing (5) forming a pump chamber (12) in which the impeller (13) is arranged, wherein the impeller housing (5) has an annular surface (49) which runs around the drive shaft (11) inside the pump chamber (12), characterized, that the annular surface (49) of the impeller housing (5) located within the pump chamber (12) points outwards, and that the impeller (13) has an inwardly directed annular surface (50) which surrounds the annular surface (49) of the impeller housing (5) on the outside. A submersible centrifugal pump according to claim 10 including an impeller (13) according to any one of claims 1 to 9. Submersible centrifugal pump according to claim 10 or 11, in which the impeller housing (5) has an upper wall (19) with a surface (48) which extends along an upper side of the impeller (13), in particular parallel or equidistant to that of the plate (41 ) side facing away from the additional blades (47). Submersible centrifugal pump according to one of claims 10 to 12, in which the drive shaft (11) is surrounded by an inner tube (17) and an outer tube (4), the outer tube (4) and the inner tube (17) each extending between the impeller housing (5) and the seat (6), an inner surface (30) of the outer tube (4) and an outer surface of the inner tube (17) forming an annular riser channel (18) for the liquid (9) to be pumped, wherein a plurality of transverse lines (22) each pass through the inner tube (17), the riser channel (18) and the outer tube (4), which a space (23) inside the inner tube (17) with a space (24) outside the outer tube ( 3) connect, wherein the impeller housing (5) has an upper wall (19) which is connected to the inner tube (17) and to the outer tube (4), wherein a plurality of channels (21) are arranged in the upper wall (19) of the impeller housing (5), through which the pump chamber (12) is connected to the riser channel (18), and each of the channels (21) at its opening (28) into the riser channel (18) predetermining a flow direction (29) which runs along the inner surface (30) of the outer tube (4) between two of the transverse lines (22). Submersible centrifugal pump according to one of Claims 10 to 13, in which the drive shaft (11) is mounted exclusively on that side of the seat (6) which is remote from the impeller housing (5). Submersible centrifugal pump according to Claim 14, in which the impeller (13) is at a distance of more than 500 mm, in particular 600 mm to 800 mm, from the seat surface (6).

Images