EP1375924B1 - Centrifugal pump volute - Google Patents

Description

TECHNICAL AREA

The invention relates to a housing of a centrifugal pump according to the preamble of claim 1.

STATE OF THE ART

A housing of the generic type is from the EP-A-0 455 542 known. A guide device is part of a pump chamber formed from two concentric chambers. This pump chamber consists on the one hand of a rotationally symmetrical center chamber with T-shaped axial section, which is called blade chamber and in which concentrically rotates the blade wheel, and on the other hand of a guide forming annular Umfangsförderkammer, an axial section in the form of an inverted L with rounded corner and has a substantially constant width and which radially and then axially extends the Schaufelradkammer at the level of the arms of the T-shaped axial section. The two peripheral housing walls of the annular circumferential conveying chamber are each formed circular, so that the passage cross section of the circumferential conveying chamber, seen over the circumference, is immutable.

In one of the GB-A-1 013 341 (Figures 16 and 17) known guide device, the circumferentially-dependent change in the passage cross-section of the annular channel is achieved in that the multi-part second housing part forms a concentric to the pump axis rotating, outwardly open annular channel of constant width and radial depth, in the groove bottom a ring with over the The scope of variable radial thickness is embedded in a form-fitting manner. Apart from the fact that an impeller enclosing the outside of the outer ring-free annular space constant passage cross-section is connected via an adverse cross-sectional reduction with the above guide device, the surfaces coming into contact with the product to be conveyed are relatively entangled designed guide only extraordinarily expensive to bring by suitable surface processing method to a surface finish, as required for centrifugal pumps, which are used for example in the food and beverage sector. In addition, the suction nozzle is in atypically guided for centrifugal pumps, which are used in the aforementioned application areas from the outside into the intake of the impeller, where it must be penetrated by the impeller driving shaft. This penetration creates considerable problems with respect to the processing methods applicable there for producing a sufficient surface quality.

It is also known that centrifugal pumps in sheet metal construction can meet the above-mentioned surface quality requirements most likely. The DE-A-20 47 541 shows a pump housing formed from two deep-drawn housing parts, in which the guide device bounded on the outside by a circular peripheral wall of the first housing part and the spiral space is formed by a spirally extending pulling at least one housing wall of the housing over the circumference of the impeller. The proposed geometry of the pump housing and its guide designed relatively complicated and the proposed connection and sealing of the two housing parts together is cleaning technology and hygienic problematic.

A centrifugal pump, wherein the two housing parts are integrally formed and in which a raised portion which is integrally formed on the impeller carrying the second housing part has a varying around the center of the second housing part diameter to form a spiral surface, the figures reveal 3 to 6 of the EP-B-0 316 392 , However, according to the preamble of claim 1 of this document, a centrifugal pump is placed under protection with a for rotation in a plane within the spiral outflow channel (annular channel) and centrally attached to the circular Innenumfangswandung the first housing part impeller. By the raised shape of the helical surface forming portion identically created favorable conditions for the production of a sufficient surface quality.

In addition, Figure 7 shows the EP-B-0 316 392 a centrifugal pump in which, in contrast to the above solution, the outflow channel (annular channel) is formed in the first housing part penetrated by the suction nozzle, wherein the spiral surface is also determined in this case by a diameter of a raised section which varies around the center of the first housing part, which is also cheap to edit.

Finally, the reveals WO 88/09438 From which the EP-B-0 316 392 has emerged in Figure 8, a further embodiment of a two each one-piece housing halves having centrifugal pump, wherein the spiral-shaped outflow (annular channel) is formed on a likewise low-machined raised portion which is integrally formed on the impeller carrying the second housing part. However, this is done here by varying the width of the outflow channel as a function of its circumferential extent.

Housing for centrifugal pumps in sheet metal design increasingly compete there with those with cast housings, where the price / performance ratio on the one hand and the weight, the absence of pores and the surface quality of the rolled starting material on the other hand become decisive selection criteria for a centrifugal pump. Casing wall thicknesses manufactured in rolled material are only dependent on the working pressure of the centrifugal pump, whereas in cast casings for technical reasons a minimum wall thickness must not be undershot, which in many cases is oversized in view of the occurring stress. In contrast, cast housings are generally regarded as dimensionally stable and thus functionally reliable; their shape is well known (see for example DE 25 29 458 C2 or company publication 5.046.1, Tuchenhagen, centrifugal pumps, series VPB, VPC, VPD ... L, Otto Tuchenhagen GmbH & Co. KG, D-21510 Büchen).

It is now everywhere, where low efficiency losses are tolerated on the one hand and on the other hand, the cost of such a centrifugal pump play a crucial role in the selection, looking for cost-effective solutions for centrifugal pumps in sheet metal construction.

It is an object of the present invention to simplify the guide device and housing of a centrifugal pump of the generic type such that a cost reduction over known housing geometries is possible without the possibility of carrying out the housing in sheet-metal construction is lost.

SUMMARY OF THE INVENTION

This object is solved by the features in claim 1. Advantageous embodiments of the pump housing according to the invention are the subject of the dependent claims.

The prerequisite for the solution of the problem is to form a ring channel limiting annular channel housing not as an independent housing component, which must then be necessarily connected to a first and a second housing part (see, eg DE 195 34 258 C2 ), or provide a separate ring whose circumferentially variable cross-section determines the circumferential variation of the passage cross-section of the annular channel (see, eg GB-A-1 013 341 ), but the annular channel housing in a conventional manner ( EP-A-0 455 542 ) integrally integrate into the second housing part. This is achieved by the fact that the first and the second housing part are each formed in one piece, that surrounds the impeller surrounding a vaneless annular space constant passage cross section immediately and without cross-sectional reduction in the annular channel and that the annular channel is bounded on the side of the second housing part of a first radial annular surface which is oriented substantially radially, which continues after the inner annular channel housing wall latter and which is sealed together with the outer annular channel housing wall. Furthermore, on the inside of the second housing part the impeller and on the outside a housing parts supporting Mounting flange arranged, whereby the center of the first housing part is available for the coaxial connection of an inlet connection.

In this case, the connection of the pressure port to the first housing part designed both in the spiral annular channel and in the annular channel with variable over the circumference, the respective collected fluid flow from the impeller bearing passage cross-section relatively easily. The more critical connection conditions are in the spiral annular channel. The inner annular channel housing wall is formed in the connection area of the pressure nozzle in such a way that the necessary connection cross section between the outer and inner annular channel housing wall is ensured. This is achieved by the fact that in the connection area of the pressure port, the inner annular channel housing wall is formed planar, with this flat wall surface connects tangentially to the inner annular channel housing wall in the region of the largest passage cross-section of the (spiral) annular channel. At its other end, the flat wall surface is adapted with a curved surface to the inner annular channel housing wall in the region of the narrowest passage cross-section of the (spiral) annular channel.

The one-piece housing parts can be performed by their relatively simple geometry without particular difficulties in sheet metal design, so that there are very favorable conditions for a sufficiently good surface quality of all coming into contact with the product inner surfaces of the centrifugal pump.

The relatively simple geometry of the first and the second housing part in the region of the outer contour of the impeller makes it possible to adapt the two housing parts with relatively narrow annular gaps to the impeller, whereby the efficiency is favorably influenced. The housing geometry allows for a readily the arrangement of a closed impeller in the housing without significant gap losses and Totraumbildung, on the other hand, without further narrowing of the annular gap and the housing shape, the arrangement of an impeller radial or semi-axial design with possible from the inlet to the exit region in each case to an impeller side open blade channels. Furthermore, the arrangement of an impeller of radial or semi-axial design is given with an even number n blades, the individual blade channel is bounded between the him each limiting blades either from a cover disc or from a back surface segment and, viewed in the circumferential direction, cover disc and rear surface segment follow each other in the respective change ( WO 99/39105 ).

In a broadening of the impeller with the aim of increasing the flow rate of the centrifugal pump with otherwise the same construction geometry, the axial extension region of the outer annular channel housing wall, i. the axial extent of the first housing part, only enlarged. To the same extent, without changing the radial dimensions of the inner annular channel housing wall, the axial extent is extended. The connection region of the two housing parts on the one hand and the geometry of the centrifugal pump, seen radially, on the inside of the annular channel remain largely unchanged.

Regardless of the axial extension length of the passage cross-section of the annular channel, it is in each case fluidly advantageous that the discharge nozzle is arranged centrally to this length, as provided for an advantageous embodiment of the invention. If the volume flow of the centrifugal pump fails relatively small, so that the axial extension length of the passage cross-section of the annular channel is dimensioned correspondingly small, provides a further embodiment of the invention, that the discharge nozzle off-center to this length, offset towards the impeller, is arranged. In this case, the discharge nozzle engages at least partially in the blade-less annular space surrounding the impeller. However, no flow impediments result from this situation, since according to the invention the vaneless annular space passes into the annular channel without cross-sectional reduction.

The sealing of the two housing parts together in the outer region of the annular channel is particularly hygienic and easy to clean if in the first radial annular surface a sealing groove is provided, in which a housing seal is arranged in an annular channel directed to the annular gap between the outer ring channel housing wall and the first radial annular surface herausulstet and largely flush with the interior contour of the annular channel.

While the sealing of the first and the second housing part takes place optimally directly on their merger in the region of the annular channel, the coaxial centering of the two housing parts is made to each other in a particularly effective manner to a maximum outer diameter, the housing of the centrifugal pump has to offer. For this purpose, a further embodiment of the invention provides that the first radial annular surface continues over the region of the sealing groove in a substantially radially outward direction and that adjoins the outer annular channel housing wall a corresponding to the first radial annular surface and releasably connected second radial annular surface connects, which has a recess at its outer end, with which it comprises the peripheral boundary surface of the first radial annular surface on the outside.

Another advantageous embodiment of the guide device provides to form these in the form of a spiral annular channel. A continuously widening passage cross section of the spiral annular channel, with the best possible efficiencies can be achieved, it is limited in its outer boundary area by the outer ring channel housing wall which surrounds the pump axis concentric and with a constant radius of curvature, thus circular. The required by the spiral profile cross-sectional change over the circumference of the annular channel is carried by the inner annular channel housing wall, which is designed in the required manner with a variable over the circumference, the spiral course forming local radius of curvature. Thus, the entire requirements for the geometry of the passage cross-section of the Ring channel in the second housing part, as far as they relate to the configuration of the continuously changing over the circumference spiraling course.

However, in the second housing part according to the invention integrated annular channel offers in the context of the overall arrangement even more advantages. The ability to disassemble the first housing part alone, is given by the proposed solution, so that an immediate access to the impeller is maintained without putting the drive motor connected to the second housing part via a mounting flange. The ability to separate the impeller including shaft and drive motor from the rest of the housing without having to dismantle the suction and discharge line from the housing, is also retained by the proposed solution. This process design is ensured by the arrangement of the pressure port on the outer ring channel housing wall.

BRIEF DESCRIPTION OF THE DRAWINGS

Figur 1

in perspektivischer Darstellung eine Kreiselpumpe gemäß der Erfin- dung in Verbindung mit einem Antriebsmotor;

Figur 2

einen Meridianschnitt durch die Kreiselpumpe gemäß Figur 1 , resul- tierend aus einem in Figur 1 mit A-A gekennzeichneten und durch die Pumpenachse waagerecht verlaufenden Schnittverlauf, wobei die Leitvorrichtung gemäß einer vorteilhaften Ausführungsform als spiral- förmiger Ringkanal ausgebildet ist und

Figur 3

einen Querschnitt durch die Kreiselpumpe gemäß Figur 1 , wobei der Schnittverlauf in Figur 1 mit B-B gekennzeichnet ist, die Schnittebene senkrecht von der Pumpenachse durchdrungen wird, die Innenteile der Kreiselpumpe entfernt wurden und lediglich das erste und das zweite Gehäuseteil im in Frage kommenden Bereich dargestellt sind.

An embodiment of the guide device for a housing of a centrifugal pump according to the invention is shown in the figures of the drawing and will be described below. Show it

FIG. 1

a perspective view of a centrifugal pump according to the invention in connection with a drive motor;

FIG. 2

a meridian section through the centrifugal pump according to FIG. 1 , resulting from an in FIG. 1 marked with AA and extending horizontally through the pump axis cutting profile, wherein the guide device is formed according to an advantageous embodiment as a spiral-shaped annular channel and

FIG. 3

a cross section through the centrifugal pump according to FIG. 1 , where the cutting path in FIG. 1 is marked with BB , the cutting plane is penetrated vertically by the pump axis, the internal parts the centrifugal pump have been removed and only the first and the second housing part are shown in the area in question.

DETAILED DESCRIPTION

One of a first and a second housing part 2, 3 existing housing 1 of a centrifugal pump is mounted on a mounting flange 10 on a flying motor 8 FIG. 1 ). To the first housing part 2, viewed in the direction of the pump axis, an inlet connection 5 and, tangentially opening circumferentially, a discharge nozzle 6 is connected, which ends via a conical extension 6a in a connecting piece 6b.

From the in FIG. 1 with AA marked cutting curve results in accordance with the meridian section FIG. 2 , The first and the second housing part 2, 3 are adapted in their radial extent range, each with a narrow annular gap, to an impeller 7 fastened to a shaft 11. On the annular circumferential impeller outlet cross-section is followed by a shovelless annular space 4a on the outside, which is bounded in the radial direction initially on both sides of the first and second housing part 2, 3 and then outside bounded by a transition surface 2d of the first housing part 2. This transition surface 2d is then continued in an outer annular channel housing wall 2a, wherein this has the shape of a cylinder jacket, ie, a constant radius of curvature, the outer radius R _a , has. The second housing part 3 is formed in the region of the impeller 7 as a radially extending disk. In the outer region of this disc, a mainly axially oriented, the impeller 7 in the axial direction fortstrebende, the pump axis enclosing inner ring channel housing wall 3a connects, the local radius of curvature r _i is variable to realize the helical course over the circumference. The outer and inner annular channel housing wall 2a, 3a thus form between them the ever-changing passage cross section of a spiral annular channel 4 *. Nevertheless, with the proposed solution, a ring channel 4 with variable over the circumference, the collected liquid flow from the Impeller 7 bill carrying passage cross-section feasible. Even a vane-free annular space 4 with a constant passage cross-section can easily be integrally integrated in the second housing part 3. The (spiral) annular channel (4 *), 4 adjoins the side of the blade-less annular space 4a and has an axial extent adapted to the volume flow conditions of the respective centrifugal pump. The axial width, which is constant over the circumference of the annular channel 4, 4 *, is in FIG. 2 marked B.

FIG. 3 shows how the spiral annular channel 4 *, seen over the circumference, steadily widened. Starting at the rearmost penetration point of the pressure port 6 with the first housing part 2, and seen in the direction of rotation n, the passage cross-section of the spiral annular channel 4 * increases steadily from a minimum cross section to a point where FIG. 3 the horizontal center line forms a vertical with a parallel to the longitudinal axis of the pressure port 6. Up to this point, the inner ring channel housing wall 3a is continuously curved (end point / connection point P). Subsequent to the end point P, a planar wall region 3b adjoins, which ensures a passage cross-section in the region of the spiral-shaped annular channel 4 * which corresponds at least to the passage cross-section of the pressure port 6. It can be seen that the planar wall region 3b has a tilt angle β directed radially inwards at the end point P and that this flat wall region 3b bridges a peripheral region defined by an exit angle α on the inner annular channel housing wall 3a. This exit angle α, which relates to the pump axis and the circumferential direction, results from the penetration area of the pressure port 6 with the outer annular channel housing wall 2a. The end region of the planar wall region 3b, as seen in the direction of rotation n, merges with a rounding radius k into the inner annular channel housing wall 3a. This transitional area is marked Q. The longitudinal distance between the end point P and the transition region Q is dimensioned such that there on the one hand the minimum required passage cross-section of the pressure port 6 and on the other hand still a sufficient circumferential length of the spiral annular channel 4 * are ensured. As a rule, the level Wall portion 3b in the area PQ can not be dimensioned lengthwise so that the nominal passage cross-section of a connecting piece 6b is achieved, the conical extension 6a between the cylindrical pressure port 6 and the connecting piece 6b for connecting a pressure line, not shown required. Alternatively, a solution is proposed in which the conical extension 6a begins at the connecting piece 6b and extends into the penetration area with the outer annular channel housing wall 2a.

The outer axial boundary of the spiral-shaped annular channel 4 * is reached via a first radial annular surface 3c, which is part of the second housing part 3 and adjoins the inner annular channel housing wall 3a in a radially oriented first radial annular surface 3c which is removed from the pump axis in the radial direction ( FIG. 2 ). The first radial annular surface 3c continues over the outermost radial extent of the outer annular channel housing wall 2a in the radial direction to the outside. Also on the outer annular channel housing wall 2a is followed by a radially oriented, with the first radial annular surface 3c and releasably connected second radial annular surface 2b connects. Both the first and the second radial annular surface 3c, 2b have a plurality of through-holes 12, which are distributed over their circumference and correspond to each other, via which the first and the second housing parts 2, 3 are connected to one another. The concentric alignment of the housing parts 2, 3 to each other succeeds by a recess 2c which is formed on the outer end of the second radial annular surface 2b and which comprises the peripheral boundary surface of the first radial annular surface 3c on the outside on a maximum possible diameter.

The annular channel 4, 4 * is sealed in the corner region, which is formed between the first and the second housing part 2, 3, by means of a housing seal 9 against the environment, wherein the housing seal 9 in a formed in this area in the first radial annular surface 3c sealing groove 3d recording takes place. In this case, the housing seal 9 bulges in a to the interior of the annular channel 4, 4 * directed annular gap between the first and the second housing part 2, 3 and largely flush with the interior contour of the annular channel 4, 4 * from.

REFERENCE LIST OF ABBREVIATIONS USED

1

casing

2

first housing part

2a

outer ring channel housing wall

2 B

second radial annular surface

2c

written settlement

2d

Transition surface

3

second housing part

3a

inner ring channel housing wall

3b

level wall area

3c

first radial annular surface

3d

seal groove

4

annular channel

4 *

spiral annular channel

4a

Bladeless annulus

5

inlet connection

6

pressure port

6a

conical extension

6b

spigot

7th

Wheel

8th

engine

9

housing seal

10

mounting flange

11

wave

12

Through holes

B

axial width of the annular channel

P

Endpoint / terminal

Q

Transition area

R _a

outer radius

R _l

inner radius

k

radius of curvature

n

direction of rotation

_i

local radius of curvature

α

exit angle

β

Tilt angle (of the flat wall area)

Claims (6)

1. A volute of a centrifugal pump that is composed of a first and a second volute part (2, 3), which are each formed as one-piece, wherein the first volute part (2) has a circular, essentially cylindrically extending outer annular channel - volute wall (2a) forming the outer periphery of an annular channel (4; 4*) and leading out from said annular channel a discharge port (6), which is tangentially connected to the outer annular channel - volute wall (2a), wherein the second volute part (3) has an inner annular channel - volute wall (3a) forming the inner periphery of the annular channel (4; 4*), said inner annular channel - volute wall (3a) runs parallel to the outer annular channel - volute wall (2a) and with an impeller area (7) disposed coaxially to the outer annular channel - volute wall (2a), and viewed in the axial direction, outside of an area enclosed by the annular channel (4; 4*), wherein a inlet port (5) is disposed coaxially to the first volute part (2), wherein a mounting flange (10) supporting the volute parts (2, 3) is disposed on the second volute part (3) inside of the impeller area (7) and outside, wherein a blade-less annular space (4a) encircling the impeller area (7) of constant passage cross section transitions directly and without a reduction in cross section into the annular channel (4; 4*), and wherein the annular channel (4; 4*) is bounded on the side of the second volute part (3) by a first radial annular surface (3c), which is essentially oriented radially, which connecting to the inner annular channel - volute wall (3a) continues the latter and which is brought together sealed with the outer annular channel - volute wall (2a)
   characterized in that,
   the inner annular channel-volute wall (3a) has a radius of curvature (r_i) variable locally over the periphery, which determines the periphery-dependent change of the passage cross section of the annular channel (4; 4*), that the inner annular channel - volute wall (3a) in the penetration area of the discharge port (6) is designed planar in the shape of a flat wall area (3b), and that this flat wall area (3b) on the one end has at its connection point (P) to the continuously curved inner annular channel - volute wall (3a) an angle of inclination (β) directed radially inward relative to the tangent at the connection point (P), and that on the other end, as viewed in the peripheral direction transitions into the inner annular channel - volute wall (3a) with a rounding-off radius (k).
2. The centrifugal pump volute according to Claim 1, characterized in that in the first radial annular surface (3c) a sealing groove (3d) is provided in which a volute seal (9) is disposed which bulges out into an annular gap directed towards the annular channel (4, 4*) between the outer annular channel - volute wall (2a) and the first radial annular surface (3c), and is extensively flush with the internal contour of the annular channel (4, 4*).
3. The centrifugal pump volute according to Claim 1 or 2, characterized in that the first radial annular surface (3c) continues outwards in an essentially radial direction beyond the region of the sealing groove (3d), and that a second radial annular surface (2b) corresponding to and detachably connected to the first radial annular surface (3c) is joined to the outer annular channel - volute wall (2a), said second radial annular surface (2b) has at its outer end a recess (2c) with which it covers the outside of the peripheral side boundary surface of the first radial annular surface (3c) on the outside.
4. The centrifugal pump volute according to one of the claims 1 to 3, characterized by a spiral shaped annular channel (4*) whose external annular channel - volute wall (2a) is designed with constant outside radius (R_a), and whose inner annular channel - volute wall (3a) is designed with the local radius of curvature (r_i) changing over the periphery, forming the spiral-shaped progression.
5. The centrifugal pump volute according to one of the Claims 1 to 4, characterized in that, the discharge port (6) is disposed centered to the axial extension length of the passage cross section of the annular channel (4, 4*).
6. The centrifugal pump volute according to one of the Claims 1 to 4, characterized in that, the discharge port (6) is disposed eccentric to the axial extension length of the passage cross section of the annular channel (4, 4*), offset in the direction toward the impeller (7).

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