EP2643596B1 - Self-cleaning centrifugal screw pump with auxiliary flushing flow behind the impeller - Google Patents

Description

The invention relates to a Schraubenzentrifugalradpumpe comprising a cover plate and a method for cleaning a Schraubenzentrifugalradpumpe comprising such a cover plate.

State of the art

The document CH 662 864 discloses a Schraubenzentrifugalradpumpe, wherein the Schraubenzentrifugalrad is rotatably mounted on a rotational axis. The Schraubenzentrifugalradpumpe has in the region of the connection between Schraubenzentrifugalrad and axis of rotation on a cavity. This per se very well-proven embodiment of a screw centrifugal pump has the disadvantage that can deposit and accumulate impurities within the cavity. This results in increased wear and / or increased maintenance.

The document US4349322 discloses a screw centrifugal pump according to the preamble of claim 1.

The document EP1041320 discloses a centrifugal pump with a secondary flow behind the impeller for the purpose of cooling a shaft seal.

Presentation of the invention

It is an object of the present invention to form a Schraubenzentrifugalradpumpe and to propose a method for cleaning a Schraubenzentrifugalradpumpe, which have more advantageous properties with respect to the attachment of impurities.

This object is achieved with a Schraubenzentrifugalradpumpe having the features of claim 1. The dependent claims 2 to 11 relate to further advantageous embodiments. The object is further achieved with a method for self-cleaning a Schraubenzentrifugalradpumpe having the features of claim 12. The claim 13 refers to a further, advantageous method step.

The object is achieved in particular with a screw centrifugal wheel pump comprising a cover plate, wherein the cover plate has a front side and a rear side, and wherein the front side has a preferably frusto-conical extending part surface whose course is adapted to the back of a Schraubenzentrifugalrades adapted, the partial surface in the center of a central opening wherein the central opening extends in the direction of an axis, and wherein the cover plate has at least one opening which in the region of the partial surface and spaced from the central opening is arranged, and wherein the aperture forms a fluid-conducting connection between the front and the back of the cover plate.

A Schraubzentrifugalradpumpe having the inventive cover plate has the advantage that forms during the pumping operation, a partial flow, which flows from the front to the back of the cover plate and then along a center opening of the cover plate flows back to the front of the cover plate, so that forms a cleaning stream, the is able to at least partially back into the cavity behind the cover plate or accumulated impurities to promote the front of the cover plate, so that these impurities can be conveyed away via the main flow of Schraubenzentrifugalradpumpe.

The screw centrifugal pump according to the invention comprises a rotatably mounted screw centrifugal wheel and a cover plate arranged directly next to the screw centrifugal wheel with a central opening, wherein a hub or a drive shaft of the screw centrifugal wheel preferably extends through the central opening. Between the center opening and the hub or the drive shaft, a fluid-conducting gap is formed. Rotating the helical centrifugal wheel in the direction of rotation causes a fluid to be conveyed along a main flow, causing a partial flow of the fluid to flow to the rear of the cover plate via an aperture spaced from the center opening, and thereafter, passing this partial flow across the fluid conducting gap flows back to the main stream, due to the between the aperture and the fluid conducting gap prevailing pressure difference. This partial flow forms a purifying fluid flow, which in particular flows through the rear space of the cover plate and supplies any impurities present therein to the skin flow.

The cover plate preferably runs on the side facing the screw centrifugal wheel or the partial surface facing the screw centrifugal wheel, so that the partial surface is preferably frusto-conical or planar, wherein the partial surface could also have a different shape, for example a curved or polygonal course.

The invention will be described below with reference to exemplary embodiments in detail.

Brief description of the drawings

Fig. 1

eine aus dem Stand der Technik bekannte Schraubenzentrifugalradpumpe;

Fig. 2

in einem Längsschnitt eine Teilansicht einer Schraubenzentrifugalradpumpe mit einem Ausführungsbeispiel einer Deckscheibe;

Figuren 3 bis 5

unterschiedlich verlaufende Durchbrechungen;

Fig. 6

eine Draufsicht auf eine Deckscheibe;

Fig. 7

eine perspektivische Ansicht der in Figur 6 dargestellten Deckscheibe;

Fig. 8

einen Schnitt durch die Deckscheibe gemäss Figur 6 entlang der Linie A-A;

Fig. 9

einen Schnitt durch ein weiteres Beispiel einer Deckscheibe;

Fig. 10, 11

schematisch einen Schnitt durch zwei weitere Beispiele von Deckscheiben;

Fig. 12

eine Draufsicht auf ein weiteres Ausführungsbeispiel einer Deckscheibe..

The drawings used to explain the embodiments show:

Fig. 1

a known from the prior art Schraubenzentrifugalradpumpe;

Fig. 2

in a longitudinal section a partial view of a Schraubenzentrifugalradpumpe with an embodiment of a cover plate;

FIGS. 3 to 5

differently extending openings;

Fig. 6

a plan view of a cover plate;

Fig. 7

a perspective view of in FIG. 6 illustrated cover plate;

Fig. 8

a section through the cover plate according FIG. 6 along the line AA;

Fig. 9

a section through another example of a cover plate;

10, 11

schematically a section through two further examples of cover plates;

Fig. 12

a plan view of another embodiment of a cover plate ..

Basically, the same parts are given the same reference numerals in the drawings.

Ways to carry out the invention

Fig. 1 shows a known from the prior art, in the document CH 662 864 disclosed embodiment of a Schraubenzentrifugalradpumpe. FIG. 1 shows an axial section through the Schraubenzentrifugalradpumpe comprising a Schraubenzentrifugalrad with a hub 21 and a Schaufelzentrifugalrad 25, comprising a drive shaft 33 which is fixedly connected to the hub 21, and comprising a disposed behind the Schraubenzentrifugalrad 25 housing rear wall 23, and the Schraubenzentrifugalrad 25 in the circumferential direction surrounding housing outer wall 3. In the housing rear wall 23, an outlet opening 36 is provided in the vicinity of the drive shaft 33, so that gases can escape, which entrained in the pumped medium and exit against the Laufradrotationszentrum and pass through the impeller rear gap between the impeller hub 21 and rear wall 23 in the interior 37. The gap between the impeller hub 21 and the housing rear wall 23 is formed as a labyrinth, wherein both the hub-side and the rear wall-side labyrinth structure is interrupted by a transverse groove 38, so that a self-cleaning effect and no conveyed solids in the interior 37 and the outlet opening 36th reach.

However, it has been shown that, despite this measure, contaminants can enter the interior 37, whereby these contaminants can deposit in the interior 37 and accumulate, so that cleaning of the screw centrifugal pump is required at certain time intervals.

FIG. 2 1 shows a pump housing 3 with inlet opening 3a or pump inlet opening 3a, outlet 3b and housing interior 3c, and further comprising a hub 21, which is connected to a vane centrifugal wheel 25 shown only schematically and dashed is, and which is rotatably mounted about a rotatable about an axis A drive shaft 33. The connection between the drive shaft 33 and the hub 21 is shown only schematically. The Schaufelzentrifugalrad 25 and the hub 21 could also, as in FIG. 1 represented as a single, shared part be designed. In the illustrated embodiment, the Schraubenzentrifugalradpumpe 1 also comprises a conical inner housing 4 with inlet opening 4a and a Abstandhaltering 5. The Schraubenzentrifugalradpumpe 1 also comprises a housing rear wall 23 with an outlet opening 36 and a seal 6. The outlet opening 36 is used for maintenance purposes and is usually closed during operation of the screw centrifugal pump 1 with a plug from the outside. During the rotation of the vane centrifugal wheel 25, a main flow F is generated which leads to the outlet 3b via the inlet opening 3a. The conveyed mainstream F comprises a fluid, preferably water and possibly gases such as water vapor, the helical centrifugal pump 1 is used in a preferred use for conveying polluted water, so that the main flow F may also include solids, such as feces, sand, gravel, textiles, Fibers, plastic parts etc.

The Schraubenzentrifugalradpumpe 1 also includes a cover plate 2, which is arranged in the direction of the axis A directly behind the hub 21 and the Schraubenzentrifugalrades 25. The cover plate 2 has a front side 2h and a rear side 2i, wherein the front side 2h in the illustrated embodiment comprises a substantially frusto-conical extending part surface 2k whose course of the back is adapted to a Schraubenzentrifugalrad 25, wherein the partial surface 2k in the center of a center opening 2g wherein the center opening 2g extends parallel in the direction of the axis A. The hub 21 extends through the central opening 2g, so that between the center opening 2g and the hub 21, a gap 2b extending in the direction of the axis A is formed. The hub 21 also has a projection which partially covers the partial surface 2k, so that a gap 2e extending transversely with respect to the axis A is formed between the hub 21 and the partial surface 2k. The Cover plate 2 has at least one opening 2a, which is arranged at a distance from center part 2g in the area of partial surface 2k, wherein opening 2a forms a fluid-conducting connection between front side 2h and rear side 2i of cover plate 2. During the pumping operation, or during the rotation of the Schaufelzentrifugalrades 25 in the direction of rotation R, the fluid in the region of the opening 2a has a higher pressure than in the region of the center opening 2g, whereby a partial flow F1 is generated by a part of the main flow F as part of flow F1 flows through the opening 2a to the back 2i of the cover plate 2, and then flows through the gap 2b and optionally the column 2e back into the main flow F. This partial flow F1 causes contaminants, which are located in the interior 37, are conveyed out of this and the main stream F are supplied.

The hub 21 could also be designed without a projection, so that no transverse gap 2e is formed. The hub 21 could also be spaced with respect to the sub-surface 2k such that no transverse gap 2e is formed. The drive shaft 33 could also be further advanced, so that the gap 2 b is formed at least partially or exclusively between the cover plate 2 and the drive shaft 33.

The cover plate 2 has a front side 2h directed towards the pump inlet opening 3a, and the front side 2h preferably has a partial surface 2k whose course is adapted to the rear side 25a of the screw centrifugal wheel 25 such that between the front side 2h of the cover plate 2 and the back side 25a of the Screw centrifugal wheel 25 a gap 2e is formed by a maximum of up to 3 mm, preferably a gap 2e in the range between 0.5 mm and 2 mm.

The cover plate 2 has at least one opening 2a and preferably at least two openings 2a. Advantageously, the openings 2a are arranged symmetrically with respect to the axis A in the partial surface 2k. The openings 2a can be configured in a variety of ways. In the FIG. 2 shown below opening 2a is in FIG. 3 shown enlarged. At the front 2h of the cover plate 2 flows a flow F2. The opening 2 comprises an inlet opening 21 whose cross-section forms an entry surface 2m. The partial flow F1 flows through the opening 2a to the rear 2i of the cover plate 2. The partial flow F1 is deflected when flowing into the opening 2a, which has the advantage that in the flow F2 located solids difficult to flow into the opening 2a. The partial flow F1 is thereby at least partially cleaned of solids because the solids remain at least partially in the flow F2 and be carried away by this.

FIG. 4 shows a further embodiment of an opening 2a. Unlike the in FIG. 3 The embodiment shown in FIG FIG. 4 represented opening 2a arranged such that the partial flow F1 is deflected with respect to the occurring at the front side 2h of the cover plate 2 flow F2 such that it undergoes a partial flow reversal. The aperture 2a extending in this way has the advantage that solids can pass through the aperture 2a to the back 2i of the cover plate 2 less effectively.

In the FIG. 2 The opening 2a shown above is in FIG. 5 shown enlarged. On the front side 2h of the cover plate 2, a recess 2c is arranged, which opens to the opening 2a, wherein the opening 2a forms an inlet opening 21 with inlet surface 2m, so that the inlet opening 21 is arranged in the recess 2c. The inlet opening 21 or the inlet surface 2m can be arranged in various ways, but advantageously as in FIG. 5 represented such that the partial flow F1 is deflected and undergoes an at least partial flow reversal with respect to the occurring at the front 2h of the cover plate 2 flow F2. The inlet opening 21 arranged in this way has the advantage that solids can pass through the opening 2a to the back 2i of the cover plate 2 less effectively. As in FIG. 5 shown, the entrance surface 2m is arranged in an advantageous embodiment such that it is parallel or substantially parallel to the axis A. In FIG. 5 is not the axis A per se, but the course of the axis A is shown. As in FIG. 5 illustrated, the entrance surface 2m is arranged in a further advantageous embodiment such that it is perpendicular or substantially perpendicular to the rotational direction R of the drive shaft 33, wherein the entrance surface 2m facing away from the rotation direction R is arranged.

The FIGS. 6, 7 and 8th show an embodiment of a cover plate 2 in plan view, in perspective view and in a section along the section line BB. In an advantageous embodiment, the recess 2c, as in the FIGS. 6 and 7 represented, at least partially by a substantially perpendicular or perpendicular to the axis A extending bore be educated. FIG. 6 shows the course of the axis A and the preferred direction of rotation R. Off FIG. 6 is thus seen that the entrance surface 2m is parallel to the axis A and perpendicular to the direction of rotation R. FIG. 8 shows in section the cover plate 2 with front 2h, back 2i and center opening 2g. In the frusto-conical or substantially frusto-conical extending part surface 2k, the openings 2a are arranged, wherein the openings 2a are always arranged at a distance from the central opening 2g. The openings 2a could also, as in FIG. 3 shown, perpendicular or substantially perpendicular with respect to the partial surface 2k run, or as in FIG. 4 shown, transverse to the part surface 2k run. According to the invention, the cover plate 2, as in the FIGS. 6 to 8 illustrated, a recess extending in the circumferential direction, in particular a spiral-shaped recess 2d, which advantageously extends in the region of the central opening 2g along the partial surface 2h to the outside. Advantageously, the depression 2d extends as in FIG FIG. 6 shown in the direction of rotation R spiral from inside to outside. This embodiment has the advantage that a contamination, which is conveyed by means of the partial flow F1 via the central opening 2g or the gap 2b to the front side 2h of the cover plate 2, is conveyed along the recess 2d towards the periphery of the partial surface 2k. In addition, the hub 21 rotating in the direction of rotation R over the part surface 2k or the screw centrifugal wheel 25 rotating in the direction of rotation R helps to move the dirt in the direction of rotation R in the depression 2d or on the part surface 2k and to move it towards the outside with respect to the part surface 2k pollution reaches the skin stream F, and is detected by this and carried away. Thus, an arrangement of the aperture 2a is particularly advantageous as in the FIGS. 6 to 8 shown. In particular from FIG. 6 It can be seen that the contamination is moved substantially in the direction of rotation R, wherein the aperture 2a is arranged in a recess 2c and the inlet surface 2m facing away from the direction of rotation R is aligned so that dirt, even if they flow over the recess 2c, due to Flow conditions and the direction of movement of the contaminants hardly or not at all flow through the opening 2a but the main stream F are supplied.

The cover plate 2 can, as in the FIGS. 7 and 8th shown, in addition, a running along the edge region recesses 2f, which is provided in particular for receiving an O-ring and thus for sealing.

FIG. 9 shows in a section of another example of a cover plate 2, which in contrast to the in FIG. 8 However, shown section has a flat part surface 2k. Otherwise, the cover plate 2 is configured similar to the in FIG. 8 illustrated embodiment by the cover plate 2 according to FIG. 9 also has a recess 2c, which opens into an opening 2a. If the spiraling depression 2d is thought away, discloses FIG. 6 a top view of the in FIG. 9 shown cover plate 2. The in FIG. 9 However, shown cover plate 2 could also have a spiral extending recess 2d, so that a plan view of this embodiment as in FIG. 6 would look like. In the FIG. 9 shown cover plate 2 also has a central opening 2g and a front side 2h and a back 2i. The front side 2h or the partial surface 2k can run in a variety of ways, such as curved, as in FIG. 10 shown schematically in a section, or edged, as in FIG. 11 shown schematically in a section. In the most preferred embodiment, the sub-surface is as shown in FIG FIG. 8 shown, frustoconical.

In an advantageous embodiment, the cover plate 2 is designed as a casting, wherein the recess 2c and advantageously also the opening 2a or the inlet opening 21 already form part of the still unprocessed casting. For the completion of the cover plate 2, it is then still essentially necessary to machine the front side 2h, in particular by removing machining machining. A cover plate 2 made of a casting designed in this way has the advantage that there are no or only very small additional costs during production, since the chip-removing machining of the cover plate 2 is required anyway. The in the FIGS. 6 to 8 shown cover plate 2, comprising two recesses 2c with openings 2a, thus, in comparison to cover plates 2 without openings 2a, are produced with negligible additional costs.

The inventive method allows self-cleaning a Schraubenzentrifugalradpumpe 1. In this case, the Schraubenzentrifugalradpumpe 1 has a rotatably mounted Schraubenzentrifugalrad 25 and an immediately adjacent or behind the Schraubenzentrifugalrad 25 arranged Cover plate 2 with a central opening 2g, wherein a hub 21 of the Schraubenzentrifugalrades 25 or the Schraubenzentrifugalrad 15 superposed axis 33 extends through the central opening 2g, so that between the central opening 2g and the hub 21 or the axis 33, a fluid-conducting gap 2b is formed. If the Schraubenzentrifugalrad 25 is rotated in the direction of rotation R and thereby a fluid along a main flow F is promoted, then a partial flow F1 of the fluid via a center opening 2g spaced opening 2a to the back 2i of the cover plate 2 and flow this flow part F1 then over the Slit 2b again flow to the main flow F, due to the prevailing between the aperture 2a and the gap 2b pressure difference. This partial flow F1 promotes any impurities in the space behind the cover plate 2 again to the main flow F. Advantageously, the cover plate 2 on the front side 2h on the part surface 2k has a spiral recess 2d, wherein the spiral recess 2d in the direction of rotation R from inside extends to the outside, so that the outgoing from the gap 2b partial flow F1 and the optionally contained therein impurities via the spiral-shaped depression 2d the main flow F is supplied.

In the illustrated embodiments, the cover plate 2 and the housing rear wall 23 are always shown as separate parts. The cover plate 2 and the housing rear wall 23 could also be designed in one piece, for example by being made of a single part, for example a cast part. Such a single casting, comprising both the cover plate 2 and the housing rear wall 23, has the advantage that this is inexpensive to produce, and that between the cover plate 2 and the rear wall 23 no seal is required. This allows a particularly low-maintenance embodiment.

FIG. 12 shows in a plan view another embodiment of the already in FIG. 6 The opening 2a and the entrance surface 2m again runs parallel to the axis A, wherein the opening 2a or the inlet surface 2m, in contrast to FIG. 6 , with respect to a radially extending through the axis A extending straight line L inclined at an angle α, wherein the angle α preferably has a value in the range of +/- 60 degrees.

The cover plate 2 could also consist of a metal sheet.

Claims (13)

1. Screw-type centrifugal wheel pump (1), comprising a pump housing (3) with a pump inlet opening (3a), comprising a screw-type centrifugal wheel (25) with a hub (21) and/or a drive shaft (33), further comprising a cover plate (2) for the screw-type centrifugal wheel pump (25), wherein the cover plate (2) comprises a front side (2h) and a rear side (2i) and wherein the front side (2h) comprises a partial surface (2k), the course of which is configured to be adapted to the rear side of a screw-type centrifugal wheel (25), wherein the partial surface (2k) comprises in its centre a central opening (2g), the central opening (2g) being configured to be adapted for the passage of a rotational axis (A) of the screw-type centrifugal wheel (25) and extending in a direction of the rotational axis (A),
   and wherein the partial surface (2h) features a spirally extending depression (2d) which, beginning substantially in a region of the central opening (2g), extends along the partial surface (2h) in a rotational direction (R) to the outside, the cover plate (2) being arranged on a side (25a) of the screw-type centrifugal wheel (25) that is situated opposite the pump inlet opening (3a), directly behind the screw-type centrifugal wheel (25),
   characterised in that
   a gap (2b) is formed between the central opening (2g) of the cover plate (2) and the hub (21) and/or the drive shaft (33), that the cover plate (2) comprises at least one through-hole (2a), which is arranged in a region of the partial surface (2k) and is spaced apart from the central opening (2g), and that the through-hole (2a) forms a fluid-conducting connection between the front side (2h) and the rear side (2i) of the cover plate (2).
2. Screw-type centrifugal wheel pump (1) according to claim 1, characterised in that the partial surface (2k) extends substantially frustoconically or substantially planarly.
3. Screw-type centrifugal wheel pump (1) according to claim 1, characterised in that the cover plate (2) comprises at least two through-holes (2a), the at least two through-holes (2a) being arranged in particular symmetrically with respect to the rotational axis (A).
4. Screw-type centrifugal wheel pump (1) according to one of the preceding claims, characterised in that, towards the front side (2h), the through-hole (2a) comprises an inlet opening (2l), that the front side (2h) comprises a depression (2c) and that the inlet opening (2l) is arranged in said depression (2c).
5. Screw-type centrifugal wheel pump (1) according to claim 4, characterised in that the inlet opening (2l) forms an inlet surface (2m) which extends substantially in parallel to the rotational axis (A).
6. Screw-type centrifugal wheel pump (1) according to claim 4 or 5, characterised in that the depression (2c) is implemented at least partly by a bore which extends substantially perpendicularly to the rotational axis (A).
7. Screw-type centrifugal wheel pump (1) according to claim 4 or 5, characterised in that the cover plate (2) consists of a cast piece and that the depression (2c), and advantageously the inlet opening (2l) as well, already form part of the unprocessed casting.
8. Screw-type centrifugal wheel pump (1) according to one of claims 1 to 4, characterised in that the through-hole (2a) extends perpendicularly or substantially perpendicularly with respect to the partial surface (2k).
9. Screw-type centrifugal wheel pump (1) according to one of claims 1 to 4, characterised in that the through-hole (2a) extends transversely with respect to the partial surface (2h).
10. Screw-type centrifugal wheel pump (1) according to one of the preceding claims in combination with one of claims 4 to 7, characterised in that the screw-type centrifugal wheel (25) features a rotational direction (R) and that the inlet surface (2m) formed by the inlet opening (2l) of the through-hole (2a) extends substantially in parallel to the rotational axis (A) and facing away from the rotational direction (R).
11. Screw-type centrifugal wheel pump (1) according to one of the preceding claims, characterised in that the spirally extending depression (2d) extends in the rotational direction (R) from the inside to the outside.
12. Method for self-cleaning of a screw-type centrifugal wheel pump (1) comprising a rotationally supported screw-type centrifugal wheel (25) as well as a cover plate (2) which is arranged directly adjacent to the screw-type centrifugal wheel (25) and comprises a central opening (2g), wherein a hub (21) or a drive shaft (33) of the screw-type centrifugal wheel (25) extends through the central opening (2g), wherein the cover plate (2) comprises a spirally extending depression (2d) on its front side (2h), wherein the spirally extending depression (2d) extends in a rotational direction (R) from the inside to the outside, wherein the screw-type centrifugal wheel (25) is rotated in the rotational direction (R) and, as a result, a fluid is conveyed along a main flow (F),
    characterised in that
    a fluid-conducting gap (2b) is formed between the central opening (2g) and the hub (21) or the drive shaft (33), that a partial flow (F1) of the fluid flows to the rear side (2i) of the cover plate (2) via a through-hole (2a) which is spaced apart from the central opening (2g), and that said partial flow (F1) then flows back to the main flow (F) via the gap (2b) due to the pressure difference prevailing between the through-hole (2a) and the gap (2b), as a result of which the partial flow (F1) exiting from the gap (2b) is fed to the main flow (F) via the spirally extending depression (2d).
13. The method according to claim 12, characterised in that the partial flow (F1) is deflected when flowing into the through hole (2a) for the purpose of thus separating off solid matter from the partial flow (F1).

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