EP1178214B1 - Centrifugal Pump - Google Patents

Abstract

The device has a housing (9) with inlet and outlet openings (1,2) and an impeller wheel (3,3',3'') rotatably mounted in a chamber on a drive shaft (13). The chamber consists of at least two parts with a sealing element (5) between them that seals the inner chamber volume. One chamber part has a stop (10) on which the other chamber part is supported so that the distance between the two chamber parts is defined by the supporting joint.

Description

The present invention relates to a centrifugal pump for conveying a fluid, consisting of a Housing with an intake and an outlet opening with an impeller in a chamber a drive shaft is rotatably mounted, wherein the chamber is formed from at least two parts, between which at least one sealing element is arranged, which seals the chamber interior.

Such centrifugal pumps are generally used for lifting, emptying, filling, circulation or promotion of liquids. The wheels are generally made of a disk-shaped Main body, on one side of which walls are applied, which usually form spiral-shaped channels. In centrifugal pumps, the necessary pressure difference under the influence of a continuous flow process reached. In this case, the liquid located in the impeller channels by the Zentrifugafkraft displaced to the outside and experiences a pressure and speed increase. Of the At the same time resulting negative pressure in the inner area leads to a uniform suction of Delivery fluid through the suction port. The undesirable in pumps speed increase is in general in a downstream system with, for example, gradually expanding channels or converted into pressure energy in a paddle-free annulus. At high pressure levels be several similar stages, each consisting of impeller and shovelless annulus, connected in series, which are flowed through in sequence by the conveyor.

It is already known, multi-stage centrifugal pumps made of thin-walled, deep-drawn Cr-Ni-Mo rolled steel manufacture. The individual stages are arranged in package construction. Every package then consists of a chamber, which in turn is formed by an impeller and a chamber pot becomes. The arrangement of several chamber pots creates several chambers in which in each case an impeller is rotatably mounted on the drive shaft. By the rotating drive shaft All impellers of the centrifugal pump are driven together. This arises in the area of Impellers a pressure difference between radially inner regions and radially outer Areas. This results in that the fluid from the intake into the radially inner Area of the first impeller is sucked. By the rotating first impeller is the medium now transported radially outwards. All wheels are essentially of a shovelless surrounded annular gap in which forms a higher pressure. This causes the Fluid on the back of the impeller on the bottom wall of the chamber pot radially to is guided inside. The chamber pot has a substantially central bore through which the subsidized medium can leave the first chamber pot and enters the second chamber pot. Also there is again an impeller arranged for a pressure difference between the radially inner Areas and radially outward areas provides. The emanating from the first chamber pot Transfer medium is then in the same way by the second impeller due to the centrifugal force transported to the outside and then runs again on the bottom wall of the second chamber pot radially inward and passes through the central opening of the second chamber pot. The described Course continues for each subsequent stage of the centrifugal pump.

The production of multi-stage centrifugal pumps made of rolled steel is very inexpensive. But it has to be for one Seal the individual chamber pots against each other worried. Therefore, in general Sealing elements, for. B. in the form of O-rings, arranged between two adjacent chamber pots. The sealing elements assume a double function, namely a support and sealing function. In other words, the sheet pots are placed on each other and pressed together for as long as possible. until the sealing ring absorbs its sealing function. However, it is due to geometric Tolerances of the sealing elements and / or the chamber pots to small deviations in the distances between adjacent chamber pots. However, to achieve high efficiency, it is required that at least the blade-provided side of the impeller to the adjacent Housing wall or the adjacent chamber pot bottom has a very small distance. On the other hand, there is a collision of the impeller with the housing wall or one adjacent It is imperative to avoid using the sealing pot as this may cause irreversible damage. To one To prevent such collision, it is therefore in the known centrifugal pumps in Paketklemmweise necessary to increase the gap between impeller and adjacent non-rotating parts, to catch any geometric tolerances. However, this leads to a not insignificant Reduction of efficiency.

To increase the efficiency, therefore, are already centrifugal pumps with closed wheels and covered Rückführstufenbeschaufelung been used. Although, by this measure the efficiency can be brought into an acceptable range, the production of closed Running wheels and a covered return stage blading is, however, very cost- and time consuming.

Another embodiment of a known centrifugal pump provides a support ring which between adjacent chamber pots is arranged and takes on an additional support function. At this Embodiment, the O-ring is "chambered". That is, the O-ring is made of the support ring, the outer wall the inner chamber pot and the inner wall of the outer chamber pot encased. By this measure, the influence of geometric tolerances of the sealing element can be reduced, but not completely stopped.

Depending on the fördemdem fluid, but especially in the sterile technology, it may be necessary only To provide completely closed surfaces within the centrifugal pump, so that a thorough residue-free cleaning of the centrifugal pump is possible. Especially in the sterile technology completely closed surfaces with a maximum surface roughness between 0.8 and 0.4 μm required. Closed impellers as well as covered return stage blading can However, they can not be produced with closed surfaces without considerable economic effort. The embodiment with chambered O-rings can not be used for the sterile area, due to the function of the delivery fluid can penetrate to the O-ring and thus into the chamber.

Therefore, in the high sterile sector pumps are not made of rolled steel, but in essence Parts turned out of solid, so that open wheels can be used. This method of production However, it is very expensive and above all costly.

US 5,201,633 describes a cast construction of a centrifugal pump which is completely sealless is executed between the step components. A seal is done only by means of O-rings on Outer sheath. EP 0 492 575 A1 discloses an interstage housing for a metal sheet Pump shown. Two elements are there sealed against each other via an O-ring, where the O-ring is arranged in a corresponding chamber. Because of the chamber arrangement it is it is not possible for the fluid to contact the o-ring during operation of the centrifugal pump.

The present invention is therefore based on the object, a cost-effective centrifugal pump for To make available, which allows the use of open wheels and possibly also in the Sterile area can be used.

According to the invention this object is achieved by a centrifugal pump with the features of claim 1 solved. In other words takes in the centrifugal pump according to the invention, the sealing element no support function, but only sealing function. In the assembled state, the distance from chamber to chamber (package size) only defined by the chamber-forming elements, but not by the sealing element. As the chamber-forming Elements can be made very accurately, the distance between impeller and adjacent non-rotating chamber walls are very small, without the risk of Collision of the impeller on the chamber walls arises. It can therefore be used open wheels be, without it comes to a reduction of the efficiency. When mounting the individual chambers or packages is to pay attention to the secure fit of the sealing element, since this never lose its sealing function.

The sealing element is arranged so that it during operation of the centrifugal pump with the fluid in Contact kicks. In this case, the sealing element is not chambered, as for example in the case described above Embodiment with an additional support ring was the case. Although the pumped medium then unhindered to reach the O-ring, but it can also be unhindered again drain from the sealing ring, and a cleaning of the pump can be done without residue.

Particularly preferred is an embodiment in which the stop outside of the by the sealing element sealed volume is arranged.

Therefore, the fluid can not come into contact with the support connection, so that this connection represents no problem for the high requirements of the sterile technology, since it is outside of the Delivery medium volume is.

A particularly useful centrifugal pump is designed in multiple stages, each stage a chamber has, in each of which an impeller is arranged. The pumping power of the centrifugal pump can be increased significantly by the multi-level training.

Particularly preferably, at least a part of the wheels is open. It is under open understood that the impeller channels have a substantially U-shaped cross-section. By the open design of the wheels can be closed surfaces with a very low surface roughness be achieved because welds can be sanded and polished, so that the high requirements of sterile technology can be satisfied. The centrifugal pump can then be used as a sterile centrifugal pump be used.

An expedient embodiment of the present invention provides that the chambers of a Housing wall and a chamber pot, from a first chamber pot and the bottom of a second Kammertopfes or from the bottom of a chamber pot, a support element and a housing wall be formed. In this case, the chamber of the first stage is generally the pump housing wall and a first chamber pot formed. The following stages have chambers, each formed from a chamber pot and the bottom of the chamber pot of the previous stage become. The last stage can either also be formed from two stacked chamber pots or from the bottom of the chamber pot of the previous stage and a support element and the housing wall.

This package design has the advantage that the individual chambers of substantially identical Parts can be produced. Impellers and chamber pots are then simply alternately on the drive shaft mounted within the pump housing.

Particularly useful is an embodiment in which the chamber pots made of deep-drawn sheet metal are made.

The chamber pot preferably has a substantially circular cross-section and a Pot bottom, wherein the bottom of the pot has a substantially central bore. The central hole serves to guide the fluid to the next chamber pot or to the next stage.

It is particularly useful if on the inside of Kammertopfbodens a preferably open return blading is arranged; because only with a return blading can one high efficiency of a multi-stage centrifugal pump can be achieved. The return blading serves, among other things, to the vortexed from the impeller and provided with a twist Collect fluid and direct it towards the central opening. It is by the helical feedback blading the swirl of the pumped medium converted into kinetic energy.

Particularly preferred is an embodiment in which the chamber pot an inwardly curved Floor has. This is fluidly of great advantage. Especially in the sterile technology is It is very advantageous if the centrifugal pump is designed such that it is at least in a mounting orientation is self-emptying.

Here, the curvature of the chamber pot is helpful. Namely, the pump of the invention is so oriented that the chamber pots are arranged with the bottom up, so flows after the Turn off the centrifugal pump still located in the pump housing fluid to the inclined Surfaces of the chamber pot inwards and can thus reach the previous pump stage. Then it flows on the preferably also inclined side of the impeller, no blading has, again axially outward, until it touches the outer surface of the lower chamber pot and at this again is guided radially inward until it reaches the previous pump stage.

This process continues until the fluid reaches the intake manifold and the pump can completely leave.

The chamber pot wall is preferably designed such that it has a stop on its outer side having. On the inside, however, it preferably has a circumferential groove. This groove serves to seal the sealing element, z. B. an O-ring record.

Particularly preferably, the chamber pot wall is formed such that they increase with increasing axial distance from the bottom wall preferably extended stepwise. This happens in the way that the upper edge of the chamber pot wall has an inner diameter which is approximately the outer diameter the lower portion of the chamber pot wall of the previous section corresponds. Therefore, the chamber pot with its outwardly widening section on the chamber pot bottom another chamber pot to be pushed. The extended section is dimensioned that he meets the stop of the chamber pot below.

Fig. 1

eine Schnittansicht durch eine erfindungsgemäße dreistufige Kreiselpumpe und

Fig. 2a und Fig. 2b

eine Schnittansicht und eine Draufsicht des Blechtopfes von Fig. 1.

Further advantages, features and applications of the present invention will become apparent from the following description of a preferred embodiment and the accompanying figures. Show it

Fig. 1

a sectional view through a three-stage centrifugal pump according to the invention and

Fig. 2a and Fig. 2b

a sectional view and a plan view of the sheet metal pot of Fig. 1st

In Fig. 1 is a section through a centrifugal pump according to the invention is shown. The centrifugal pump exists from a housing 9, an intake 1 and an outlet opening 2. Within the housing. 9 three wheels 3, 3 ', 3 "are mounted on a shaft 13. Between the wheels 3, 3', 3" are chamber pots 4, 4 'arranged. The chamber pots 4, 4 'are made of deep-drawn sheet metal with a thickness of made about 4 mm. The wheels 3, 3 ', 3 "have on their one side a spiral wall. 6 on, which form the impeller channels. The chamber pots 4, 4 'have on the inside of the pot bottom also a spiral wall 7, which serves as a return blading.

During the conveying process, the drive shaft 13, on which the wheels 3, 3 ', 3 "are mounted, set in rotation. By the rotation of the first impeller 3 is formed in the region of the first impeller 3 a pressure difference between radially inner regions and radially outer regions. As a result, the conveying medium via the intake manifold 1 centrally in the centrifugal pump is sucked in. By the rotation of the first impeller 3, the conveying medium is due to the centrifugal force transported radially outwards. The agitated fluid leaves in radial Outward direction, the first impeller 3 and reaches the annular portion 14 in which no Shovels are arranged. In this area, the kinetic energy of the pumped medium in a Pressure difference converted. The conveying medium now moves axially in the direction of the arrow in FIG. 1 and thus enters the region of the bottom of the chamber pot 4. Since the fluid through the Rotation of the impeller 3 is provided with a twist, it is by the spiral Rückführbeschaufelung 7 recorded. The return blading makes use of the swirl of the pumped medium, to guide the fluid along the inner wall of the chamber pot 4 radially inward. Of the Chamber pot 4 has a central bore 12 through which the fluid to the second impeller 3 'can get. The impeller 3 'already belongs to the second stage of the centrifugal pump. The functional Process repeats for each individual level. After the pumped medium all stages has passed through, it is discharged through the outlet port 2 from the pump.

To realize the idea according to the invention, the chamber pots 4, 4 'have an extraordinary Shape, which is made clear in the following with reference to FIGS. 2a and 2b.

As already mentioned, the chamber pot 4 has been produced from a deep-drawn sheet metal. Of the Kammertopf consists of a bottom and a cylindrical wall. As clearly seen in Fig. 2 is, the cylindrical wall of the chamber pot 4 has a step-like extension. On the outside wall thereby forms the stop 10. The inner wall of the chamber pot 4 expands yourself. In the area of the extension, a circumferential groove 11 is inserted into the wall, the recording of the O-ring 5 is used. This particular form of cylindrical wall ensures in the composite Condition for a defined distance between adjacent chamber pots 4, 4 '.

The sealing and support function according to the invention will now be illustrated with reference to FIG. 1. Clear it can be seen that the first chamber pot 4 has a chamber wall which widens. In the Groove 11 of the chamber wall of the first chamber pot 4, an O-ring 5 is inserted. The upper one extended Edge of the side wall of the chamber pot is supported on the housing 9. In the state shown the O-ring 5 is already compressed between the housing wall 9 and chamber pot 4, so that he perceives his sealing function. Nevertheless, the distance between chamber pot bottom 4 and Housing 9 is not determined by the O-ring 5, but only by the axial length of the side wall portions of the chamber pot 4. On the outer wall of the chamber pot 4 is due to the extension the side wall, a projection 10 has emerged, which serves as a stop for the upper end of the next Kammertopfes 4 'serves. Also, its side wall has an extension, so that the side wall of the second chamber pot 4 'in the upper region has an inner diameter which is approximately the Outer diameter of the lower portion of the side wall of the first chamber pot corresponds. Therefore can the side wall of the second chamber pot 4 'sleeve-like over the side wall of the first Chamber pot 4 are pushed until the outer edge 15 of the side wall of the second chamber pot 4 'on the stop 10 of the side wall of the first chamber pot 4 is supported. The chamber pot 4 'is dimensioned so that in this state, the O-ring 5 between the first and second chamber pot 4 or 4 'is already loaded, so that he perceives its sealing function. Again, it is essential that the distance between the two chamber pots 4 and 4 'is not of geometric tolerances of the sealing element 5 depends, but clearly by the metallic contact of the outer End of the side wall of a chamber pot at the stop 10 is determined. At the shown here Embodiment, the last stage has no chamber pot. Instead, a support element 8 provided, but at least on its inside expanded similarly, as the chamber pots 4, 4 'do. As a result, in the third stage, the sealing and supporting function of different parts accepted. While the support function of the defined metallic contact between the Support element 8 and the stop 10 of the second chamber pot 4 'is given, the sealing function fulfilled by the compressed O-ring 5.

In the support device of Fig. 2 is particularly well recognized that the bottom of the chamber pot 4, 4 'is slightly curved inwards. This has on the one hand fluidic advantages, on the other hand this measure together with other structural features that the centrifugal pump, if it is placed so that the drive shaft is vertically aligned so that the drawn in Fig. 1 Arrow pointing up, is self-emptying. After switching off the centrifugal pump can namely in the interior of the centrifugal pump remaining medium at the inwardly curved outer surfaces the bottoms of the chamber pots 4, 4 'flow radially inwards and into the underlying Drain level. As well as the side of the impeller 3, 3 ', 3 ", which has no blades, slightly opposite the horizontal is inclined, the medium can under the influence of gravity on this Side of the impeller flow radially outward and then to the bottom of the underlying Chamber pot 4, 4 'meet. The process described is repeated until the medium to be pumped back into the intake 1 passes.

On the inside of the bottom of the chamber pot 4, 4 'is the spiral-shaped return blading 7 appropriate. To achieve optimum blading, the number of return blades should be be equal to the number of blades of the impeller. Since the spiral-shaped blades welded 7 gap-free However, with each shovel, a corresponding work and cost commitment is required. Extensive tests have surprisingly shown that, even with a large number of Shovels in the impeller, only four return vanes lead to a very good result.

In the production of the chamber pot 4, 4 ', the following method is preferably used. First, a sheet metal blank with the final shape is pulled out of 4 mm thick stainless steel sheet. Thereafter, the return blades, preferably four pieces, are welded into the drawn round blank and in the seam area by means of grinding and polishing to the desired surface quality brought. Finally, the thus prepared round blank, together with the welded blades in pulled a second deep-drawing process gear in the final contour.

In the embodiment according to the invention, all surfaces can be arranged freely accessible and are therefore gap-free and with a surface roughness of less than or equal to 0.8 to 0.4 microns produced.

Claims (15)

1. Centrifugal pump for delivering a fluid comprising a housing (9) with an inlet and an outlet (1, 2) with an impeller (3, 3', 3"), which is mounted to rotate on a drive shaft (13) in a chamber, said chamber being formed from at least two parts, between which a sealing element (5) is arranged, which seals off the interior of the chamber, and one chamber-forming part has a stop (10), on which the other chamber-forming part is supported, so that the distance between the two chamber-forming parts is defined by the support joint, characterized in that the sealing element (5) lies open, i.e. is not enclosed by the chamber, and is arranged in such a way that it comes into contact with the fluid during the operation of the centrifugal pump.
2. Centrifugal pump according to claim 1, characterized in that stop (10) is arranged outside of the volume sealed off by sealing element (5).
3. Centrifugal pump according to one of claims 1 or 2, characterized in that the centrifugal pump is multi-stage, each stage having a chamber in which an impeller (3, 3', 3") is arranged in each case.
4. Centrifugal pump according to one of claims 1 to 3, characterized in that the impeller (3, 3', 3") is an open impeller (3, 3', 3").
5. Centrifugal pump according to one of claims 1 to 4, characterized in that the centrifugal pump is a sterile centrifugal pump.
6. Centrifugal pump according to one of claims 1 to 5, characterized in that the chambers are formed from a housing wall (9) and a pot (4, 4'), from a first pot (4') and the bottom of a second pot (4) or from the bottom of a pot (4'), a supporting element (8) and a housing wall (9).
7. Centrifugal pump according to claim 6, characterized in that at least one pot (4, 4') is made from deep-drawn sheet metal.
8. Centrifugal pump according to claim 6 or 7, characterized in that the pot (4, 4') has an essentially circular cross-section and a pot bottom, said pot bottom having an essentially central hole (12).
9. Centrifugal pump according to claim 8, characterized in that a preferably open recirculating blade system (7) is arranged on the inside of the pot bottom.
10. Centrifugal pump according to one of claims 6 to 9, characterized in that the pot (4, 4') has a bottom that is dished inwards.
11. Centrifugal pump according to claim 10, characterized in that the centrifugal pump is self-emptying.
12. Centrifugal pump according to one of claims 8 to 11, characterized in that the side wall of the pot has the stop (10) on its outside.
13. Centrifugal pump according to one of claims 8 to 12, characterized in that the pot wall has an encircling groove (11) on its inside.
14. Centrifugal pump according to one of claims 8 to 13, characterized in that the essentially cylindrical side wall of the pot broadens in steps starting from the pot bottom and roughly at half the axial height.
15. Centrifugal pump according to one of claims 8 to 14, characterized in that the radial broadening roughly corresponds to the wall thickness of the pot wall, so that the broadened section can be pushed like a sleeve onto the non-broadened section of an adjacent pot.

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