EP2420677A1 - Multi-layer circulation pump - Google Patents

Abstract

The multistage centrifugal pump has several wheels (36) in each pump stage (34) on common shaft (40). An impeller (6) and a diffuser (38) are arranged on each wheel. The liquid to be conveyed in the axial direction parallel to the rotational axis is made to enter into the impeller of first self-priming stage. The liquid from impeller of first self-priming stage is supplied to impeller of next stage in the axial direction.

Description

The invention relates to a multi-stage centrifugal pump.

Such multistage centrifugal pumps are known in particular for conveying water, wherein a plurality of impellers is arranged on a common shaft and between the individual impellers nozzles or volute are arranged, which redirect the radially emerging from an impeller fluid flow so that it in the axial direction in the central area enters the following impeller. A disadvantage of these multistage centrifugal pumps is that they are not self-priming. Ie. if they are not sufficiently filled with liquid, they can not be put into operation because they can not suck in liquid by themselves. For this purpose, thus always a previous venting is required or it may be necessary further upstream pump units to supply the multistage centrifugal pump for starting with liquid.

In view of this problem, it is an object of the invention to improve a multi-stage centrifugal pump to the effect that it is self-priming.

This object is achieved by a multi-stage centrifugal pump having the features specified in claim 1. Preferred embodiments will become apparent from the subclaims, the following description and the accompanying figures.

The multi-stage centrifugal pump according to the invention has at least two stages, each with an impeller. The wheels of the individual stages are preferably arranged on a common shaft, so that they are driven in rotation together. The shaft can be connected or connectable to a drive motor, in particular an electric drive motor. Such an electric drive motor can also be integrated with the multi-stage centrifugal pump to a pump unit.

According to the invention, at least the first stage of the several stages of the centrifugal pump is self-priming. The first stage is the one in which the liquid to be delivered first enters. From the first stage, the liquid then enters the second stage and so on. Between the individual stages, nozzles or spiral housings can be arranged, which redirect the liquid emerging radially from the impeller of a stage so that they are supplied in the axial direction to the central region or suction mouth of the following impeller. Thus, the liquid to be conveyed successively passes through the individual stages, wherein in each stage an increase in pressure takes place.

Due to the fact that the first stage is designed to be self-priming, the multi-stage centrifugal pump according to the invention can be put into operation without problems, even if it is not adequately vented. The first self-priming stage ensures that liquid is sucked in and supplied to the subsequent stages, which develop a pump action only when there is sufficient liquid filling, so that they too can absorb the liquid. The self-priming effect of the first stage is realized by the design of the impeller and / or the surrounding housing of the first stage. In this case, impeller and / or housing are preferably designed so that even when the pump is at a certain amount of liquid, which is sufficient, a conveying effect to be generated in the first stage, held in the first stage. This can be achieved by the geometric design of impeller and / or housing. Alternatively or additionally, a check valve may be arranged in the fluid inlet of the first stage, which prevents the backflow of liquid from the first stage when the pump is taken out of service. The centrifugal pump can be designed for horizontal or vertical arrangement, that is, that the central shaft which carries and drives the wheels extends horizontally or vertically.

Furthermore, the impeller of the first stage is designed so that the fluid to be delivered in the axial direction, d. H. enters the impeller parallel to the axis of rotation of the impeller or to the shaft and also in the same axial direction from the impeller and enters a second stage impeller. Ie. In the case of the impeller of the first self-priming stage, the liquid or the fluid does not exit the impeller in the radial direction, as is the case with conventional impellers of centrifugal pumps. The subsequent wheels of the other stages, however, can be configured in a conventional manner so that the fluid is accelerated in the radial direction and also exits the impeller in the radial direction and then is deflected as described to the next stage.

If the impeller of the first self-priming stage is arranged on the same shaft as the impellers of the subsequent stage or stages, a very simple embodiment is achieved, there is no separate drive for this self-priming stage, in particular no separate pump for commissioning the centrifugal pump required.

The first stage of the pump acts at least in individual operating conditions preferably as a positive displacement pump, which has an automatic intake. In particular, it is the operating conditions in which the stage is not completely filled with liquid. After complete Liquid filling can also act as the first pump stage as a centrifugal pump. To achieve this, the first stage is preferably designed in the manner of a side channel pump.

Preferably, the subsequent second stage is designed such that the fluid to be conveyed enters this impeller in the axial direction. More preferably, the fluid to be delivered also exits the impeller of the second stage in the axial direction. Thus, the second stage, such as the above-described first stage may be formed, so that this is self-priming. In this way, the suction effect can be increased.

The impeller of the first stage is more preferably located between an inlet wall and an outlet wall, wherein an inlet opening directed in the axial direction is present in the inlet wall and at least one outlet opening directed in the axial direction is present in the outlet wall. The inlet wall and the Auslasswandung thus form a housing surrounding the impeller of the first stage, wherein in addition a circumferential housing wall between the inlet wall and Auslasswandung is arranged or formed, which surrounds the impeller circumferentially. This peripheral housing wall may be part of the inlet and / or outlet wall.

The outlet opening in the outlet wall preferably opens in a section of the outlet wall, which extends substantially transversely to the longitudinal or rotational axis of the impeller. Starting from the outlet wall, the outlet opening extends as an outlet channel, preferably obliquely inclined radially inwardly and opens at the outlet end in an area of the suction mouth of an impeller of an adjacent pump stage. Thus, the channel formed by the outlet opening directs the flow emerging from the first self-priming stage to the suction mouth of an adjacent impeller of a second one Pump stage. The channel of the outlet opening thus preferably extends from the outlet wall to an opposite outer surface of an outlet housing. In this case, a flow deflection takes place in the channel formed by the outlet opening. The flow can enter the outlet opening in the axial direction and is then directed obliquely radially inwards by the passage of the channel of the outlet opening.

In the Auslasswandung more preferably a side channel is formed, which allows the function of the first stage as a side channel pump. This side channel is preferably connected to the outlet opening. The side channel extends in the direction of the impeller facing surface of the Auslasswandung in the form of a depression. In this case, the side channel extends annularly so that it covers the blades of the impeller of the first stages. However, the side channel does not extend over the full circumference but is interrupted by a web in its circumferential direction of extent. In this case, the webs facing ends of the side channel are preferably formed so that the channel is flatter and / or narrower there, d. H. the cross-section of the channel decreases transversely to its circumferential direction of extent. In this way, a compression route is created.

The inlet and outlet openings are preferably located at different angular positions with respect to the axis of rotation. In this way, a direct axial flow through the delivery chamber of the first stage prevents ver. The inlet port is located at an angular position with respect to the longitudinal axis located near a first end of the side channel while the outlet port is located at an angular position located near the second circumferential end of the side channel. The inlet opening is preferably located radially further inside than the outlet opening. This is beneficial since the liquid is in the impeller is accelerated in the radial direction and is thus pressed to the Au Benumfang the impeller and the surrounding pumping chamber.

More preferably, a vent opening is formed in the Auslasswandung next to the outlet opening for the liquid to be conveyed. In this way, liquid and gas or air in the first self-priming stage can be separated from each other, so that then a smaller amount of gas is supplied via the outlet opening for the liquid of the subsequent second stage, which ideally then the commissioning of the second stage and / or subsequent stages , which are preferably designed as pure centrifugal pump units, allows. Alternatively, as described above, the second stage may be self-priming. The vent opening is preferably arranged in an angular position with respect to the longitudinal axis in the vicinity of the outlet opening for the liquid.

Preferably, however, the outlet opening for the liquid to be conveyed is radially further spaced from the axis of rotation than the vent opening. The liquid is accelerated radially outwards while the impeller rotates, while gas or air collects in the radially inner space of the impeller. In this way, liquid and gas with appropriate arrangement of the outlet openings, d. H. the outlet for the liquid and the vent, to be separated from each other.

According to a further preferred embodiment, the first impeller has a plurality of blades which extend between a hub and a radially spaced outer ring. The outer ring surrounding the impeller circumferentially is thus connected to the radial end faces of the blades. The outer ring prevents the funded fluid is pressed radially outward from the impeller and thus supports the conveying direction in the axial direction.

The vanes preferably each extend in the radial direction between the hub and the outer ring. Alternatively, they may extend parallel to the radius. Thus, for example, the blades can engage approximately tangentially to the hub and then extend parallel to the radius to the outer ring.

Conveniently, the blades are each inclined to the rotation axis. Preferably at an angle between 2 ° and 20 °, more preferably between 5 ° and 10 °. Ie. the transverse axis of the blades transversely to the radius is inclined at this angle to the axis of rotation. Due to the inclination of the blades, a conveying effect in the axial direction is achieved.

According to a further preferred embodiment, the inlet wall are part of an inlet housing and / or the outlet wall part of an outlet housing, wherein the inlet and / or the outlet housing are preferably integrally molded. Particularly preferably, the inlet housing and / or the outlet housing are manufactured as plastic parts by injection molding. In addition to the inlet wall or the outlet wall, the inlet housing and / or outlet housing in particular also comprise the peripheral wall of the pump housing or a part of this circumferential wall.

Fig. 1

eine Explosionsansicht einer ersten Pumpenstufe der erfindungsgemäßen Kreiselpumpe,

Fig. 2

eine Schnittansicht der ersten Stufe der erfindungsgemäßen Kreiselpumpe gemäß Fig. 1, ebenfalls im explodierten Zustand,

Fig. 3

eine Draufsicht auf das Einlassgehäuse von der Außenseite her gesehen,

Fig. 4

eine Draufsicht auf das Einlassgehäuse von der Innenseite her gesehen,

Fig. 5

schematisch die Anordnung der Laufradschaufeln gemäß einer ersten Ausführungsform der Erfindung,

Fig. 6

schematisch die Anordnung der Laufradschaufeln gemäß einer zweiten Ausführungsform der Erfindung, und

Fig. 7

eine Schnittansicht einer mehrstufigen Kreiselpumpe mit einer selbstansaugenden ersten Stufe gemäß der Erfindung.

The invention will be described by way of example with reference to the accompanying drawings. In these shows:

Fig. 1

an exploded view of a first pump stage of the centrifugal pump according to the invention,

Fig. 2

a sectional view of the first stage of the centrifugal pump according to the invention Fig. 1 , also in the exploded state,

Fig. 3

a top view of the inlet housing seen from the outside,

Fig. 4

a top view of the inlet housing seen from the inside,

Fig. 5

3 schematically shows the arrangement of the impeller blades according to a first embodiment of the invention,

Fig. 6

schematically the arrangement of the impeller blades according to a second embodiment of the invention, and

Fig. 7

a sectional view of a multi-stage centrifugal pump with a self-priming first stage according to the invention.

The first stage of the multi-stage centrifugal pump assembly according to the invention is self-priming. The first stage has an inlet housing 2, an outlet housing 4 and an impeller 6. The inlet housing 2 forms an inlet wall 8 which, viewed in the direction of the axis of rotation X, is axially adjacent to the impeller 6. The outlet housing 4 forms a Auslasswandung 10, which faces the opposite axial side of the impeller 6. The outlet housing 4 moreover has a peripheral wall 12 situated on the outer circumference of the outlet wall 10, which extends in the axial direction as far as the inlet wall 8, thus surrounding the impeller 6 on the outside. Thus, a housing surrounding the impeller 6 is created. In addition, a mounting sleeve 14 for attachment of the impeller 6 on a shaft not shown here and two bearings 16 for mounting the mounting sleeve 14 in or on the inlet housing 2 and the outlet housing 4 is provided. The sleeve 14 is positively connected to the hub 18 of the impeller 6.

The impeller 6 is formed so that, starting from the central hub 18, a plurality of impeller blades 20 extend radially outward. The blades 20 are surrounded on the outside by an outer ring 22, which thus adjoins the radial end faces of the blade 20. The blades each extend in a plane which is inclined to the axis of rotation X, so that upon rotation of the impeller, a force in the axial direction, d. H. in the direction of the longitudinal axis X is exerted on the liquid.

The impeller blades may extend radially from the hub 18, as shown schematically in FIG Fig. 5 shown, or slightly offset parallel to the radius in the circumferential direction, as in Fig. 6 shown. Thus, the blades 20 in this embodiment do not extend directly radially to the axis of rotation toward the hub 18 but rather tangentially to the hub 18. D. h. the blades 20 are arranged at their inner end radially offset from the axis of rotation X.

The inlet housing 2 has a central opening 24 in the inlet wall through which the shaft driving the wheels extends. Radially outwardly offset, an axially directed inlet opening 26 is formed. Through the inlet opening 26, the liquid to be conveyed enters the interior of the space defined between inlet housing 2 and outlet housing 4 and into the impeller 6. By rotation of the impeller 6, it is rotated by the blades 20 for one in rotation and thereby accelerated axially to the other and axially due to the inclination of the blades to the longitudinal axis X.

In the outlet housing 4, in the outlet wall 10 facing the impeller 6, an annular, concentric with the longitudinal axis X is close the outer circumference extending side channel 28 is formed. The side channel 28 is formed as a groove or depression in the impeller 6 facing side of the Auslasswandung 10. In this case, the side channel 28 does not extend over the entire circumference about the longitudinal axis X around, but is, as in Fig. 1 can be seen interrupted by a bridge 30. Towards the web 30, the bottom of the side channel is chamfered in the axial direction, so that the cross section transversely to the circumferential direction of extension of the side channel 28 decreases towards the web. The inlet opening 26 is in the assembled state on one side of the web, while the discharge opening 32 formed in the outlet housing 4 is located on the other side of the web in the circumferential direction. The surface geometry of the side channel 28 is formed at the area adjacent to the web 30 so that there forms a negative pressure during the rotation of the impeller 6, whereby the desired suction effect arises and liquid can be sucked through the inlet opening 26, even if the impeller. 6 only filled with a small amount of liquid.

The outlet opening 32 extends as in FIG Fig. 2 can be seen, from the Auslasswandung 10 to the longitudinal axis X inclined to the subsequent pump stage 34 so that the channel formed by the outlet 32 extends obliquely, inclined radially inwardly and the output side in the central region of the adjacent pump stage 34 opens and so the flow to the central suction mouth the subsequent impeller 36 of the adjacent pump stage 34 leads. The channel formed by the outlet opening 32 opens inside an annular projection 33 on the side of the outlet housing 4 facing away from the outlet wall 10. The projection 33 is, as in FIG Fig. 7 can be seen, surrounded by the outside of the suction mouth 35 of the adjacent impeller 36. Thus, the outlet opening 32 leads the flow emerging from the first self-priming step into the seam and 35 of the impeller 36 of the adjacent pumping stage 34.

In addition to the outlet opening 32 may still be provided a separate vent opening, which is then preferably arranged radially further inboard than the outlet opening 32, so that here gas and liquid can be separated from each other. In the example shown here no separate vent opening is provided. Here, the gas, as in conventional centrifugal pumps, dissipated.

Fig. 7 shows the overall view of a multi-stage centrifugal pump with a first stage, which is self-priming as described above, and in this example, nine other conventional stages 34. These stages each have an impeller 36 and a nozzle 38, which the flow radially inwardly Suction mouth of the following impeller 36 supplies. The wheels 36 are arranged with the impeller 6 of the first self-priming stage on a common shaft 40. The shaft 40 is driven in rotation by a drive motor, not shown here. As described above, the liquid to be conveyed enters the inlet housing 2 through the inlet opening 26 and is then first conveyed through the impeller 6 through the outlet opening 32 to the subsequent pump stages 34 as described above. Since the first pump stage, as described, is designed to be self-priming, it can supply the liquid to be conveyed to the following non-self-priming pump stages 34, so that the pump as a whole can be put into operation in a self-priming manner.

LIST OF REFERENCE NUMBERS

2

inlet housing

4

outlet housing

6

Wheel

8th

Einlasswandung

10

outlet wall

12

peripheral

14

shell

16

camp

18

hub

20

shovel

22

ßenring

24

opening

26

inlet port

28

side channel

30

web

32

outlet

33

annular projection

34

pump stages

35

ugmund

36

impellers

38

nozzles

40

wave

X

axis of rotation

Claims (12)

Multi-stage centrifugal pump with at least two stages, characterized in that at least a first stage is self-priming, wherein the first stage comprises an impeller (6) which is designed such that the liquid to be conveyed in the axial direction parallel to the axis of rotation (X) in the Impeller (6) enters and in the same axial direction (X) from the impeller (6) off and enters a second-stage impeller. Multi-stage centrifugal pump according to claim 1, characterized in that the impeller of the second stage is configured such that the liquid to be conveyed in the axial direction emerges from the impeller of the second stage. Multi-stage centrifugal pump according to claim 1 or 2, characterized in that the impeller (6) of the first stage between an inlet wall (8) and an outlet wall (10) is arranged, wherein in the inlet wall (8) in the axial direction (X) directed inlet opening (26) and in the outlet wall (10) at least one in the axial direction (X) directed outlet opening (32) is present. Multistage centrifugal pump according to Claim 3, characterized in that the outlet opening (32) extends obliquely, radially inwardly, as an outlet channel, starting from the outlet wall (10). Multi-stage centrifugal pump according to claim 3 or 4, characterized in that the inlet opening (26) and the outlet opening (32) are located at different angular positions with respect to the axis of rotation (X). Multi-stage centrifugal pump according to one of claims 3 to 5, characterized in that in the outlet wall (10) adjacent to the outlet opening (32) for the liquid to be conveyed, a vent opening is formed. Multi-stage centrifugal pump according to claim 6, characterized in that the outlet opening (32) for the liquid to be conveyed from the axis of rotation (X) is radially further spaced than the vent opening. Multi-stage centrifugal pump according to one of the preceding claims, characterized in that at least the first impeller (6) has a plurality of blades (20) which extend between a hub (18) and a radially spaced outer ring (22). Multi-stage centrifugal pump according to claim 8, characterized in that the blades (20) each extend in the radial direction or each offset parallel to the radius. Multi-stage centrifugal pump according to claim 8 or 9, characterized in that the blades (20) are each inclined to the axis of rotation (X), preferably at an angle between 2 and 20 °, more preferably between 5 and 10 °. Multi-stage centrifugal pump according to one of claims 3 to 10, characterized in that the inlet wall (8) part of an inlet housing (2) and / or the outlet wall (10) part of a Outlet housing (4) are, wherein the inlet (2) and / or the outlet housing (4) are preferably integrally molded. Multi-stage centrifugal pump according to one of claims 3 to 11, characterized in that in the outlet wall (10) connected to the outlet opening (32) side channel (28) is formed.

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