EP3295034B1 - Centrifugal pump with sliding rotor - Google Patents

Description

The invention relates to a centrifugal pump, in particular a water pump, which is designed as a radial pump or a semi-axial pump, with an impeller rotatably arranged in a housing about an axis and connected to a drive shaft, which impeller has an impeller main body with impeller blades and an impeller cover disk, with the impeller outlet width being adjusted of the impeller, the main impeller body and the impeller cover body are axially displaceable relative to one another via an adjustment device, the main impeller body being arranged axially displaceably on the drive shaft or the impeller cover body, and the adjustment device being operatively connected to the main impeller body, the impeller cover body being groove-shaped on the front side facing the main impeller body Has pockets for receiving the impeller blades.

In particular, when used as coolant pumps for internal combustion engines to drive vehicles, there is a requirement for a low minimum coolant flow in the warm-up phase of the internal combustion engine and demand-based regulation corresponding to the operation of the internal combustion engine.

Centrifugal pumps which can be regulated by adjusting the impeller outlet width are known. The regulation of the impeller outlet width has, in comparison with a throttle regulation via split ring slide, as it is for example from the EP 1 657 446 A2 is known, the advantage of lower losses and a higher degree of efficiency, since no energy is destroyed, but only the energy required in each case is transferred to the fluid.

In the EP 2 299 120 A1 the impeller blades are connected to an impeller support disk on the drive and pressure side. The adjustment of the impeller outlet width between an idle position and a pumping position takes place by means of a suction-side control disk which has slots corresponding to the impeller blades and rotates with the impeller support disk.

The U.S. 4,798,517 A discloses a pump with an impeller carrying impeller blades, the outlet width of which can be varied by a suction-side control disc, the control disc having slots corresponding to the impeller blades in order to be pushed over the impeller blades. A similar centrifugal pump with variable geometry is also from the U.S. 5,169,286 A or the U.S. 4,828,455 A known.

The disadvantage is that relatively high flow losses occur in operating areas of the pump in which the unneeded impeller blade outlet width protrudes through the slots of the control disk into the water space, which worsens the efficiency of the pump in these operating areas. Another disadvantage is that this concept is only suitable for two-dimensional blade contours, but not for three-dimensional, i.e. spatially curved, impeller blade shapes, such as those from the AT 506 342 B1 , the DE 100 50 108 A or the JP S59-165895 A are known. With three-dimensionally curved impeller blades, the pump efficiency of centrifugal pumps can be significantly improved.

Another centrifugal pump with variable geometry, whereby the impeller blade outlet width is changed by a control disk, which is pushed over the impeller blades of the axially immovable impeller, is from the U.S. 4,828,454 A known. The solution described in this publication differs from the one described mainly in that the impeller blade outlet width that is not required does not protrude into the water space, but into grooves in the suction-side control disk that are covered on the impeller suction mouth and impeller outer diameter. Flow losses also occur here, albeit somewhat less than in the publications mentioned above. The cover plate is hydraulically displaced in the axial direction and reset mechanically by means of a spring, with the impeller blade outlet width being smaller the higher the pump delivery pressure. Therefore, only a delivery flow limitation is possible, but the requirements for a low minimum coolant flow in the warm-up phase and a needs-based regulation according to the operation of the internal combustion engine cannot be realized. Due to the space required by the adjustment mechanism and the return springs in the cover disk, only impeller designs that are open on the suction side can be used; the flow channel cannot be designed optimally. A similar solution is also from the US 2005/118018 A known, but here an eccentrically attached adjusting device is provided.

In the case of the DE 103 44 309 A1 The delivery pump described, the delivery rate change is carried out by an axially displaceable control disk arranged on the drive and pressure side. Conveyor blades are arranged on the drive shaft in an area facing away from the drive side and delimit pump conveying spaces with an axial conveying wall. The pump chambers are axially delimited on the side opposite the axial conveying wall by the end face of the control disk.

The U.S. 6,074,167 A discloses a variable geometry centrifugal pump wherein the impeller has an inner disc and an outer ring between which two-dimensional, spiral-shaped impeller blades are arranged. Between the inner disk and the outer ring there is an axially displaceable control disk which has spiral-shaped slots for the impeller blades. By axially moving the control disk between the inner disk and the outer ring of the impeller by means of an actuator, the impeller blade length can be switched between short impeller blades for low delivery rates and long impeller blades for high delivery rates.

The pamphlet DE 102 47 424 A1 describes a radial pump with a pump impeller, which can be moved axially out of the suction channel into a passive area by a thermocouple. The passive area is formed by a cover disk which is provided on the open flanks of the impeller blades and which seals the suction channel against the flow direction towards the housing. The impeller blades protrude through the cover disk, which leads to increased flow losses. Only a two-dimensional blade shape is possible.

The DE 10 2014 217 489 A1 discloses a similar water pump with a radial impeller, which has an axially movable impeller part with rotor blades and an axially fixed impeller part. The axially fixed impeller part has openings whose shape corresponds to the rotor blades. The blades can thus be pushed into the openings to adjust the flow. Here too, only two-dimensional blades are possible. The DE 1 703 139 A shows a similar radial centrifugal pump.

The DE 10 2011 005 476 A1 discloses a controllable cooling pump for the cooling circuit of an internal combustion engine with a blade wheel rotatably mounted about an axis of rotation, which has a pressure-side rear wall carrying blades, wherein the blades protrude into a blade space. The impeller has a cover part on the suction side and is connected to a driven hollow shaft, a push rod being guided in the hollow shaft in an axially displaceable manner. A guide body is arranged between the cover part and the paddle wheel and is connected to the push rod and can be axially displaced by means of this to regulate the coolant flow. The blades are three-dimensionally curved and the guide body can be rotated about the axis of rotation relative to the blade wheel. However, especially in the important suction area, no three-dimensional impeller blade geometry is possible. Comparatively high adjusting forces are necessary to adjust the guide body.

From the EP 2 354 552 A2 describes a water pump with an impeller, which is rotatably mounted on a drive shaft and arranged to be axially displaceable is. The impeller can be drive-connected to the drive shaft via a switchable clutch arrangement.

Furthermore, from the US 2010 006 044 A a water pump with variable capacity is known, whereby not the impeller width, but the axial position of the impeller is adjusted. The regulation takes place by increasing or decreasing the gap losses, whereby the pump has to be operated with relatively poor efficiency.

The invention is therefore based on the object of ensuring active and reliable regulation with very low drive power over the entire speed and temperature range in centrifugal pumps - in particular with spatially curved impeller blade geometry.

According to the invention, this takes place in that the impeller blades - at least in the area of the suction mouth - are three-dimensionally curved.

The three-dimensional curvature of the impeller blades within the diameter of the suction mouth enables the centrifugal pump to be particularly efficient.

The main impeller body is to be understood here as that first part of the multi-part impeller which carries the impeller blades, that is to say to which the impeller blades are fixedly and immovably connected. That second part of the impeller which closes off the blade channels on the end face remote from the main impeller body is referred to here as the impeller cover body. The impeller cover body can deviate from a purely cylindrical disc shape. In particular, the front side of the impeller cover body facing the main impeller body can have a, for example, concavely curved surface which is designed in accordance with the optimal flow conditions in the blade channels.

Operationally connected means that the adjustment device is physically connected to its function for adjusting the main impeller body with the main impeller body. Depending on the design of the adjusting device, this connection can be of a mechanical, hydraulic, pneumatic or electromagnetic type.

Due to the design of the impeller according to the invention, the pressure distribution on the impeller results in a significantly lower axial thrust compared to conventional impeller designs and thus lower adjustment forces. The impeller cover body is preferably rigidly connected to the pump shaft, that is to say non-rotatably and non-displaceably. The impeller cover body is thus drive-connected to the drive shaft so that it cannot be displaced and rotated.

It is particularly advantageous if the pockets on the rear side of the impeller cover body facing away from the main impeller body are closed. The depth of the pockets of the impeller cover body is dimensioned in such a way that the pockets can accommodate the impeller blades completely or predominantly - except for a defined minimum impeller outlet width when the main impeller body is axially displaced.

Because the impeller cover body is arranged on the side of the main impeller body facing away from the suction side, and the main impeller body on the suction side - and not the impeller cover body - is adjusted, flow losses can be avoided. There are no axially protruding parts on the suction side, which could possibly have a negative effect on the efficiency. The impeller blades can dip into pockets of the impeller cover body.

If the spatial curvature of the impeller blades goes beyond the diameter of the suction mouth, then the pockets can also be three-dimensionally curved in accordance with the three-dimensional impeller blade shape. In this case, the main impeller body should be designed to be pivotable about the axis of rotation by at least a defined angular range relative to the impeller cover body in order to enable the impeller blades to be displaced into and out of the pockets. The angular range is defined by the pitch of the three-dimensionally curved impeller blades. In the event of an axial adjustment of the main impeller body, it is rotated in accordance with the pitch of the impeller blades relative to the angular position of the impeller cover body.

Apart from this slight relative rotational movement when the main impeller body is displaced, the main impeller body is drive-connected to the impeller cover body and is therefore driven by the latter, that is to say rotated about the axis of rotation. This drive connection is most easily made directly through the form fit between the impeller blades and the pockets acting in the direction of rotation. In order to avoid an independent adjustment of the impeller outlet width as a result of the rotational movement of the impeller, it is advantageous if the axial position of the main impeller body can be fixed by the adjusting device in every adjustment position.

Particularly low adjustment forces for the impeller outlet width adjustment are required if the axially displaceable main impeller body has the suction mouth the centrifugal pump forms. In the case of three-dimensionally curved impeller blades with closed blade channels in particular, calculations and tests have shown that adjusting the impeller outlet width by shifting the main impeller body has particular advantages compared to shifting a control disk known from the prior art, since significantly lower adjustment forces are required. The reason for this is that the pressure forces acting on both sides of the main impeller body at least approximately cancel each other out when the main impeller body is arranged on the suction side, so that the resulting axial force acting on the main impeller body is very small or even approximately zero.

In a preferred embodiment it is provided that the main impeller body is arranged on the side of the impeller facing away from the drive side. The impeller cover body is advantageously arranged on the drive side of the impeller facing away from the suction mouth.

In order to keep pressure and flow losses as small as possible in every shifting position of the impeller main body, it is particularly advantageous if the impeller main body is sealed on the side facing away from the impeller cover body from the housing via at least one labyrinth seal. It is particularly advantageous if a labyrinth seal is arranged between the main impeller body and the housing of the pump both in the area of the suction mouth of the impeller and near the exit from the impeller. The labyrinth seal consists in a known manner of intermeshing elements of the impeller main body and the housing, in the simplest case of an annular projection of one part which engages in a correspondingly shaped and dimensioned annular groove of the other part.

The main body of the impeller can be adjusted in the most varied of ways, mechanically, electromagnetically, pneumatically, hydraulically or thermally.

Mechanical adjustments can be implemented, for example, by screw gears or thrust gears.

In a first embodiment variant according to the invention with a helical gear, the adjusting device can have a threaded spindle that can be rotated via an actuator and a spindle nut, wherein the threaded spindle is rotatably mounted within the drive shaft designed as a hollow shaft and the spindle nut is in contact with the main impeller body, and the spindle nut and the Impeller main body in the axial direction immovable, preferably rotatable relative to one another, are connected to one another.

In a second embodiment variant according to the invention with a thrust gear, the adjusting device can have a thrust gear with a push rod which can be displaced via an actuator and which is connected to a push sleeve, the push rod being mounted axially displaceably within the drive shaft designed as a hollow shaft and the push sleeve being connected to the main impeller body , and wherein the thrust sleeve and the impeller main body are connected to one another in an axially immovable manner, preferably rotatable relative to one another.

In a third embodiment variant according to the invention with an electromagnetic actuator it is provided that the electromagnetic actuator has at least one electromagnet fixed to the housing and at least one, preferably ring-shaped permanent magnet, which is permanently connected to the main impeller body, the at least one permanent magnet preferably in the area of one of the main impeller body and the housing sealing labyrinth seal is arranged.

Fig. 1

eine erfindungsgemäße Kreiselpumpe in einer ersten Ausführungsvariante in einem Längsschnitt;

Fig. 2

eine erfindungsgemäße Kreiselpumpe in einer zweiten Ausführungsvariante in einem Längsschnitt;

Fig. 3

eine erfindungsgemäße Kreiselpumpe in einer dritten Ausführungsvariante in einem Längsschnitt;

Fig. 4

eine erfindungsgemäße Kreiselpumpe in einer vierten Ausführungsvariante in einem Längsschnitt in einer ersten Endstellung;

Fig. 5

diese Kreiselpumpe in einer zweiten Endstellung in einem Längsschnitt;

Fig. 6

eine erfindungsgemäße Kreiselpumpe in einer fünften Ausführungsvariante in einem Längsschnitt in einer ersten Endstellung;

Fig. 7

diese Kreiselpumpe in einer zweiten Endstellung in einem Längsschnitt; und

Fig. 8

ein Laufrad der in Fig. 6 und Fig. 7 dargestellten Kreiselpumpe in einer Schrägansicht.

The invention is explained in more detail below on the basis of the non-limiting exemplary embodiments. Show it:

Fig. 1

a centrifugal pump according to the invention in a first embodiment variant in a longitudinal section;

Fig. 2

a centrifugal pump according to the invention in a second variant in a longitudinal section;

Fig. 3

a centrifugal pump according to the invention in a third variant in a longitudinal section;

Fig. 4

a centrifugal pump according to the invention in a fourth variant in a longitudinal section in a first end position;

Fig. 5

this centrifugal pump in a second end position in a longitudinal section;

Fig. 6

a centrifugal pump according to the invention in a fifth variant in a longitudinal section in a first end position;

Fig. 7

this centrifugal pump in a second end position in a longitudinal section; and

Fig. 8

an impeller of the in FIGS. 6 and 7 centrifugal pump shown in an oblique view.

Parts with the same function are provided with the same reference symbols in the exemplary embodiments.

The FIGS. 1 to 7 each show a centrifugal pump 1 with a two-part housing 2 in which a multi-part impeller 3 is arranged. The impeller 3 consists of an impeller main body 4 and an impeller cover body 5, wherein a plurality of three-dimensionally curved impeller blades 6 are fixedly connected to the impeller main body 4, for example made in one piece with it. The impeller cover body 5 is non-rotatably and also non-displaceably connected to a drive shaft 7 which is rotatably supported around the axis 8 by means of shaft bearings 9 in the housing 2. The drive shaft is driven, for example, by means of a belt pulley 7a via a traction means (not shown).

The main impeller body 4 is mounted on the impeller cover body 5 in an axially displaceable manner. A direct connection between the drive shaft 7 and the main impeller body 4 is not provided in the examples. The main impeller body 4 is arranged on the suction side 10 of the centrifugal pump 1 and forms the suction mouth 11. The impeller cover body 5 is arranged on the drive side 12 and has a front side 13 facing the impeller main body 4, which, together with the impeller blades 6 and the inner side 14 of the impeller main body 4, spans closed blade channels 15. The impeller cover body 5 has groove-like pockets 16 on the front side 13 which are shaped in accordance with the three-dimensional curvature of the impeller blades 6. The pockets 16 are designed to be closed towards the rear side 17 of the impeller cover body 5 facing away from the impeller main body 4 and are designed such that the impeller blades 6 can at least predominantly be pushed in.

The impeller blades 6 and the pockets 16 form a form fit in the direction of rotation, so that the main impeller body 4 is driven by the impeller cover body 5 via this form fit, while the impeller cover body 5 is driven directly by the drive shaft 7.

In the area of the pressure side 18, the housing 2 of the centrifugal pump forms an outlet spiral 2a.

The impeller main body 4 on the suction side is mounted so as to be axially displaceable in the hub 5 a of the impeller cover body 5. The impeller blades 6 of the impeller main body 4 can dip into the pockets 16, whereby the impeller blade outlet width b can be adjusted between a minimum value and a maximum value by moving the impeller main body 4. A smooth sliding of the impeller main body 4 on the impeller cover body 5 can be achieved if the impeller material is modified with lubricants. The pockets 16 in the impeller deck 5 can be covered with a cover 5b forming the rear side 17 of the impeller cover body 5 in order to avoid pressure-side flow losses.

In order to avoid flow losses due to short-circuit flows between the pressure side 18 and suction side 10 in every position of the impeller main body 4, labyrinth seals 20, 21 are arranged between the impeller main body 4 and the housing 2, with the in the FIGS. 1 to 3 An inner first labyrinth seal 20 in the area of the suction mouth 11 and an outer second labyrinth seal 21 in the area of the outer diameter 4b of the main impeller body 4 facing the pressure side 18 is provided in the embodiment variants shown. In the FIGS. 4 to 7 The illustrated embodiment variants, the first and second labyrinth seals 20, 21 are combined and arranged directly adjacent. Each labyrinth seal 20, 21 consists of intermeshing elements 20a, 20b; 21a, 21b of the impeller main body 4 and the housing 2, for example from an annular projection 20a, 21a of one part, for example of the impeller main body 4, which engages in a corresponding annular groove 20b, 21b of the other part, for example of the housing 2. The cylindrical projections 20a, 21a together with the corresponding annular grooves 20b, 21b of the housing 2 form the labyrinth seals 20, 21.

The impeller main body 4 is adjusted via an adjusting device 22 in the axial direction along the axis 8 of the drive shaft 7 - in the case of the FIGS. 1 to 5 Variants shown against the force of a return force formed by a return spring 23 - shifted.

The adjustment of the main impeller body 4 can take place in the most varied of ways mechanically, electromagnetically, pneumatically, hydraulically or thermally. In the Fig. 1 and Fig. 2 is a mechanical adjustment, in Fig. 3 an electromagnetic adjustment is provided.

Fig. 1 shows a first embodiment of the invention, wherein the adjusting device 22 has a helical gear 24 with a threaded spindle 26 rotatable via an actuator 25 and a spindle nut 27, the threaded spindle 26 and the spindle nut 27 being designed as a high-helix thread drive. The threaded spindle 26 is rotatably supported within the drive shaft 7, which is designed as a hollow shaft, via slide bearings 19 and is axially secured. A seal 19a is arranged between the threaded spindle 26 and the drive shaft 7. The spindle nut 27 is connected to the impeller main body 4, the spindle nut 27 and the impeller main body 4 being connected to one another so as to be immovable in the axial direction and rotatable relative to one another.

The threaded spindle 26 can be rotated clockwise or counterclockwise via the actuator 25. In uncontrolled operation, for example in the event of failure of the actuator 25, the spindle nut 27 is moved by the return spring 23, which is mounted in the impeller cover body 5 and designed as a compression spring, the hub 4a of the impeller main body 4 and an axial bearing 28 against a stop 29 on the threaded spindle 26, whereby failsafe sets the maximum impeller blade outlet width b _max . In controlled operation, the spindle nut 27 is moved, depending on the required function, via the actuator 25 and the threaded spindle 26 against the axial bearing 28, the hub 4a of the main impeller body 4 and the return spring 23, thus setting the desired impeller blade outlet width b. The actuator 25 can be formed, for example, by a stepping motor 30 and a spur gear drive 31.

Fig. 2 shows a second embodiment variant according to the invention, wherein the adjusting device 22 has a thrust gear 32 with a push rod 33 and a push sleeve 34. In this case, the push rod 33 is slidably mounted in the hollow drive shaft 7 by means of slide bearings 19 and is sealed by at least one seal 19a. The push rod 33 protrudes centrally through the bearing 35 of the actuator 25, a stop 29, which can be secured against rotation, being firmly connected to the push rod 33 at the first end 33a of the push rod 33. The push rod 33 can be moved via the actuator 25 in the direction of the pulley 7a. At the second end 33b of the push rod 33, the push sleeve 34 is firmly connected to the push rod 33. In uncontrolled operation, for example if the actuator 25 fails, the push rod 33 is moved in the direction of the suction side by the return spring 23 mounted in the impeller cover body 5, the hub 4a of the main impeller body 4 and the axial bearing 28 until the stop 29 on the bearing 35 of the actuator 25 pending, whereby the maximum impeller blade outlet width b _{max is} set in a fail-safe manner. In regulated operation, the push rod 33, depending on the required function, is moved via the actuator 25 in the direction of the pulley 7a and thus deflected via the push sleeve 34, the axial bearing 28 and the hub 4a of the impeller main body 4 against the return spring 23, which is designed as a compression spring, and thus the desired impeller blade outlet width b set. The actuator 25 can for example be a pneumatic, hydraulic or electrical lifting element.

Fig. 3 shows a third embodiment variant according to the invention, the adjusting device 22 having an electromagnetic actuator 25. The adjustment device 22 has at least one permanent magnet 36 firmly connected to the main impeller body 4 and an electromagnet 37 firmly connected to the housing 2. The permanent magnets 36 and corresponding electromagnets 37 can be in the area of the outer labyrinth seal 21 be arranged. In uncontrolled operation, for example if the actuator 25 fails, the main impeller body 4 is moved in the direction of the suction side 10 by the return spring 23 mounted in the impeller cover body 5, for example designed as a compression spring, and the hub 4a of the main impeller body 4 until the hub 4a of the main impeller body 4 is moved The stop 29 arranged on the drive shaft 7 is present, the maximum impeller blade outlet width b _max being set fail-safe. In controlled operation, depending on the required function, the impeller main body 4 is moved against the return spring 23 in the direction of the drive side 12 by a corresponding energization of the electromagnet 37, thus setting the desired impeller blade outlet width b.

In the FIGS. 4 and 5 The fourth embodiment variant shown has the adjusting device 22 as in FIG Fig. 1 a helical gear 24 with a threaded spindle 26, which can be rotated via an actuator 25, and a spindle nut 27. The threaded spindle 26 is rotatably supported within the drive shaft 7, which is designed as a hollow shaft, via slide bearings 19 and is axially secured. A seal 19a is arranged between the threaded spindle 26 and the drive shaft 7. The spindle nut 27 is connected to the impeller main body 4, the spindle nut 27 and the impeller main body 4 being connected to one another so as to be immovable in the axial direction and rotatable relative to one another.

The threaded spindle 26 can be rotated clockwise or counterclockwise via the actuator 25. In uncontrolled operation, for example in the event of failure of the actuator 25, the spindle nut 27 is moved by the return spring 23, which is mounted in the impeller cover body 5 and designed as a compression spring, into the position shown in FIG Fig. 4 End position shown with maximum impeller blade outlet width b _max moved. In regulated operation, the spindle nut 27 is moved against the return spring 23 via the actuator 25 and the threaded spindle 26, depending on the required function, and the desired impeller blade outlet width b is thus set. The actuator 25 can be formed, for example, by a stepping motor 30 and a spur gear drive 31.

The FIGS. 6 and 7 show a fifth embodiment variant according to the invention, the adjusting device 22 having a push gear 38 with a push rod 33 and a push sleeve 34. In this case, the push rod 33 is slidably mounted in the hollow drive shaft 7 by means of slide bearings 19 and is sealed by at least one seal 19a. The push rod 33 is connected at a first end 33a via a linkage 38 to the actuator 25 and can be moved via this in the direction of the belt pulley 7a. At the second end 33b of the push rod 33, the push sleeve 34 is firmly connected to the push rod 33. In regulated operation, the push rod 33 is moved, depending on the required function, via the actuator 25 in the direction of the belt pulley 7a and thus deflected via the thrust sleeve 34, the axial bearing 28 and the hub 4a of the impeller main body 4 and thus the desired impeller blade outlet width b is set. The actuator 25 can for example be a pneumatic, hydraulic or electrical lifting element.

Fig. 8 FIG. 13 shows an impeller main body 4 of the impeller 3 of FIGS FIGS. 6 and 7 The centrifugal pump shown here 1. The main impeller body 4 contains a plurality of three-dimensionally curved impeller blades 6, wherein in the exemplary embodiment each rotor blade 6 has a first section 6a and a second section 6b essentially axially adjoining it. The first section 6a is essentially two-dimensional, that is to say in a normal plane ε on the axis 8 of the drive shaft 7 or push rod 33, curved and designed such that it can dip into the groove-shaped pockets 16 of the impeller cover body 5. In the second section 6b, the impeller blades 6 are curved three-dimensionally. This second section 6b also remains in FIG Fig. 7 second end position shown outside the pockets 16.

In each of the design variants, an active and reliable regulation of the centrifugal pump 1 with very low drive power can be achieved over the entire speed and temperature range.

Claims (14)

1. Centrifugal pump (1), in particular a water pump, which is designed as a radial pump or mixed flow pump, comprising an impeller (3) which is arranged in a housing (2) so as to be rotatable about an axis (8) and is connected to a drive shaft (7), which impeller (3) comprises an impeller main body (4) having impeller blades (6) and an impeller cover body (5), wherein, for adjustment of the impeller outlet width (b) of the impeller (3), the impeller main body (4) and the impeller cover body (5) are axially displaceable relative to one another via an adjusting device (22), wherein the impeller main body (4) is arranged in an axially displaceable manner on the drive shaft (7) or the impeller cover body (5), and wherein the adjusting device (22) is operatively connected to the impeller main body (4), wherein the impeller cover body (5) has groove-shaped pockets (16) on the front side (13) facing the impeller main body (4) for accommodating the impeller blades (6), characterised in that the impeller blades (6) are curved three-dimensionally - at least in the region of the suction mouth (11).
2. Centrifugal pump (1) according to claim 1, characterised in that the impeller cover body (5) is rigidly connected to the drive shaft (7).
3. Centrifugal pump (1) according to claim 1 or 2, characterised in that the pockets (16) on the rear side (17) of the impeller cover body (5) facing away from the impeller main body (4) are formed in a closed manner.
4. Centrifugal pump (1) according to claim 3, characterised in that the pockets (16) are also curved three-dimensionally according to the three-dimensional shape of the impeller blades.
5. Centrifugal pump (1) according to claim 4, characterised in that the impeller main body (4) is arranged relative to the impeller cover body (5) so as to be pivotable about the axis (8) through at least a defined angular range.
6. Centrifugal pump (1) according to one of claims 1 to 5, characterised in that the impeller main body (4) is drive-connected to the impeller cover body (5) and driven thereby.
7. Centrifugal pump (1) according to one of claims 1 to 6, characterised in that the impeller main body (4) forms the suction mouth (11) of the centrifugal pump (1).
8. Centrifugal pump (1) according to one of claims 1 to 7, characterised in that the impeller cover body (5) is arranged on the drive side (12) of the impeller (3) facing away from the suction mouth (11).
9. Centrifugal pump (1) according to one of claims 1 to 8, characterised in that closed blade channels (15) are formed between the impeller main body (4) and the impeller cover body (5).
10. Centrifugal pump (1) according to one of claims 1 to 9, characterised in that the impeller main body (4) is sealed off from the housing (2) on the side facing away from the impeller cover body (5) by means of at least one labyrinth seal (20, 21).
11. Centrifugal pump (1) according to one of claims 1 to 10, characterised in that the adjusting device (22) comprises a screw gear (24) with a threaded spindle (26) rotatable via an actuator (25) and a spindle nut (27), wherein the threaded spindle (26) is rotatably mounted within the drive shaft (7) formed as a hollow shaft and the spindle nut (27) is connected to the impeller main body (4), and wherein the spindle nut (27) and the impeller main body (4) are connected to each other so as to be non-displaceable in the axial direction, preferably rotatable relative to each other.
12. Centrifugal pump (1) according to one of claims 1 to 10, characterised in that the adjusting device (22) has a thrust gear (32) with a push rod (33) displaceable via an actuator (25), which push rod (33) is connected to a push sleeve (34), wherein the push rod (33) is mounted in an axially displaceable manner within the drive shaft (7) formed as a hollow shaft and the push sleeve (34) is connected to the impeller main body (4), and wherein the push sleeve (34) and the impeller main body (4) are connected to one another so as to be non-displaceable in the axial direction, preferably rotatable relative to one another.
13. Centrifugal pump (1) according to one of claims 1 to 12, characterised in that the adjusting device (22) comprises an electromagnetic actuator (25).
14. Centrifugal pump (1) according to claim 13, characterised in that the electromagnetic actuator (25) comprises at least one electromagnet (37) fixed to the housing and at least one preferably annular permanent magnet (36) which is fixedly connected to the impeller main body (4), wherein preferably the at least one permanent magnet (36) is arranged in the region of a labyrinth seal (20, 21) sealing the impeller main body (4) and the housing (2).

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