EP2818721A1 - Centrifugal pump - Google Patents

Abstract

The centrifugal pump (1) has a plurality of pump stages, which are arranged axially between a head part (4) and a foot part (2). The pump stages are circumferentially surrounded by an outer shell (3), wherein one axial end of the outer shell (3) is fixed to the head part, the other axial end of the foot part and the mechanical connection between the head part (4) and foot part (2) through the outer shell ( 3) is formed.

Description

The invention relates to a centrifugal pump with several pump stages.

There are multi-stage centrifugal pumps are known in which a plurality of pump stages, each consisting of a pump impeller and a surrounding spiral housing, are arranged between a head part and a foot part, wherein the wheels are arranged on a common shaft. In this case, head part and foot part, including the pump stages, are connected to one another via external tie rods in the form of screws.

Such a centrifugal pump typically has four screws, which extend on the outside along the pump stages. In this case, embodiments are known in which the spiral housing in the pump stages form the outer shell or those in which a liquid return within the housing, typically the foot, takes place, which have an outer shell which forms an annular channel between the outer sides of the spiral housing and the outer shell , via which the delivery fluid flows from the head part to the foot part or optionally also vice versa.

Both versions have in common that the screws, with which the head and foot part are clamped, including the pump stages or, where appropriate, the surrounding outer sheath, abut in the region of the head and foot, but have a certain distance in the pump stages. The latter causes the temperature of the screws of the pumped liquid and thus also that of the volute casing or the outer shell can deviate not insignificant, which leads to thermal stresses within the centrifugal pump. Such thermal stresses can lead to premature wear or failure of the pump.

Another disadvantage of this design is that depending on the number of pump stages not only shaft and possibly outer sheath must be provided in different lengths, but that the head and foot connecting screws must be available in different lengths to order depending on the number Pump steps to connect the head and foot sections, including the pump stages.

Against this background, the invention has the object, a multi-stage centrifugal pump in such a way that on the one hand thermal stresses within the pump avoided, or at least reduced and on the other hand, the variety of components in the construction of series with different number of stages is reduced.

This object is achieved by a centrifugal pump having the features specified in claim 1. Advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the drawings. In this case, according to the invention, the features specified in the dependent claims and the description in each case but in a suitable combination, the inventive solution according to claim 1 further.

The centrifugal pump according to the invention has a plurality of pump stages, which are arranged axially between a head part and a foot part. It also has an outer sheath surrounding the pump stages circumferentially. According to the invention, an axial end of the outer shell on the head part and the other axial end of the foot part of Centrifugal pump attached, wherein the mechanical connection between the headboard and footboard is formed by the outer shell.

The basic idea of the solution according to the invention is therefore to use the outer casing, which is generally present anyway, for clamping the pump stages between the head part and the foot part. The outer jacket thus forms the mechanical connection between the headboard and footboard. The axial ends of the outer sheath are therefore fixed according to the invention, but preferably releasably, indirectly or directly attached to the foot part and the head part. In this way, the otherwise required tie rods can be omitted. The outer jacket is, if this forms the annular return channel within the centrifugal pump, always acted upon by the temperature level of the pumped liquid, so that thermal stresses are largely avoided, since the outer jacket and pump stages and head and foot part always have the same temperature level. In embodiments which have the outer shell only for fastening purposes, in which therefore no annular channel is formed, the outer shell is expediently at the pump stages, d. H. formed on the outside of the spiral housing, fitting, in order to produce a heat-conducting connection to this if possible.

In the simplest form, the outer jacket may have a cylindrical shape and be clamped radially in the head and foot part or be firmly connected to the head or foot part via essentially radially arranged screws. These screws can for example be guided by corresponding holes which are arranged distributed over the circumference of the outer shell at its end, and fixed in the head or foot part. Preferably, however, the outer jacket is formed radially widened at its axial ends, as this an equally simple and effective attachment is possible, on the other hand, the assembly is very simple, as a funnel-shaped Recording results, which allows easy mounting on the outer circumference of the pump stages.

Such a widened axial end of the outer jacket is advantageously fastened by means of an overlapping flange on the head part or on the foot part. The widening of such an outer jacket, which is typically formed of sheet metal, is simple in terms of manufacturing technology and at the same time, in conjunction with the flange fastening, enables uniform application of force over the entire circumference, which is particularly advantageous. In this arrangement, the outer sheath may also be formed of non-metallic materials, such as fiber composites.

In this case, the flange connection is preferably designed so that the connection between outer shell and headboard or foot is done both kraftals and positive. In this case, the positive locking gives a high level of security against failure of the connection, whereas the frictional connection ensures that the forces are introduced evenly distributed over the circumference and usually no further securing means against release of the connection must be provided.

The axial ends of the outer sheath may be flared conical, but then Koni appropriate on the headboard or foot and flange side provided. In that regard, it may be favorable, stepwise widen the axial ends of the outer shell, so that either only a flange-like, substantially radially extending ring at each end of the outer shell is formed or preferably a real stage, ie, a subsequent to the flange ring shell portion, which runs substantially parallel to the rest of the outer jacket. Such a true step-like training can absorb particularly high tensile forces, even if the radial extent of the flange-like portion only comparatively is small. It is understood that then in the head or in the foot part of the centrifugal pump and in the flange, a corresponding step should be provided to support the respective axial end of the outer shell and to clamp.

The flange engaging over the axial end of the outer shell and advantageously designed as an annular loose flange preferably has a first contact surface which bears against the widened axial end of the outer jacket and a second contact surface which bears against the head part or the foot part. A uniform and safe introduction of force into the respective components can take place via these contact surfaces.

Advantageously, a fastening of a flange via recesses in the flange, are passed through the fastening means with which the flange is fixed to the headboard or on the footboard. Typically, this head screws are provided which pass through the recesses in the flange and engage in corresponding threaded holes in the headboard or footboard.

In particular, when the axial ends of the outer shell are formed radially widened, it is expedient to form such a loose flange for attachment to the head part or foot part of at least two flange parts, since otherwise the mounting flanges must be mounted before the formation of the last widening on the outer shell, which is production- and mounting technology is rather unfavorable. In the case of a multi-part, in particular two-part, flange, on the other hand, it is possible to attach the outer casing only during assembly of the centrifugal pump. Assembly technology, it is particularly advantageous if a flange is formed from two or more identically shaped flange parts.

In this case, according to an advantageous embodiment of the invention, the at least two flange portions are formed overlapping at their ends, being provided in the overlap region mutually aligned recesses for the implementation of fastening means. In this way, z. As with a screw which passes through such recesses in the overlapping area, both the attachment of the flange in this area as well as the attachment of the flange to each other, which is especially with regard to the introduction of force of the flange advantageous. The flange or the flange parts are advantageously designed as castings. Since they typically require high forces, the flanges or flanges are made of metal, preferably stainless steel.

Alternatively, the flange may also be formed from a plurality of flange formed from sheet metal parts, which are reinforced in the region of recesses, ie where the Schraubbefestigung done by preferably also made of sheet metal support parts. These sheet metal parts including the support members are advantageously formed as stamped parts and joined together, for example by welding, so they can be produced particularly cost-effectively in mass production and are preferably made of stainless steel.

Instead of a flange is alternatively provided according to the invention, the determination of the radially expanded portion of the outer shell to a radially projecting and circumferentially extending bead on the head part and / or foot part, by means of a clamping ring, which has a substantially U-shaped cross section and the surrounds the widened part at the end of the outer shell and the bead and defines in this way the outer shell on the bead of the head part or foot part. In this case, the encircling bead is advantageously stepped down to the jacket, such that the radially widened end of the jacket can be inserted flush into the step, in order to be able to move a cross-sectionally U-shaped clamping ring to be fixed positively on the bead. Such an open clamping ring is almost 360 ° encircling and provided at its ends with a clamping device, such as a clamping screw, with which the distance between the ring ends can be changed to each other. Such a clamping ring is first opened so far that it can be pushed over the bead and the flared end of the outer shell, after which the clamping ring is tightened by reducing the distance of the ring ends and this, including the flared end of the outer shell and the bead to this Applies components and thus the outer shell firmly connects to the headboard or footboard.

The fastening means, with which at least one flange is connected to the head part or the foot part of the centrifugal pump, are advantageously designed as screws, which are arranged in the axial direction and engages a correspondingly extending threaded bore in the head or foot part. However, the attachment can also take place by other means, for example via a circumferential cross-sectionally C-shaped clamping ring, which surrounds the flange on the one hand and a corresponding head or foot-side bead on the other hand or via appropriate brackets.

The outer jacket of the centrifugal pump according to the invention is advantageously made of sheet metal, preferably made of stainless steel sheet.

Constructively, the centrifugal pump according to the invention is advantageously designed so that a fluid inlet of the pump on the head part or the foot part and a fluid outlet of the pump on the head part or the foot part are arranged and that between the outer walls of the pump stages and the outer shell, an annular channel for guiding the conveying fluid is formed , This makes it possible, on the one hand, to design the centrifugal pump as an inline pump or at least pressure and suction nozzles to arrange on the footboard or possibly also on the headboard. This arrangement also ensures a nearly uniform heat distribution over all components.

Fig. 1

in stark vereinfachter perspektivischer Ansicht eine Kreiselpumpe mit Antriebsmotor,

Fig. 2

in stark vereinfachter, vergrößerter, teilgeschnittener perspektivischer Ansicht den Übergangsbereich zwischen Fußteil und Außenmantel der Pumpe gemäß Fig. 1,

Fig. 3

einen Längsschnitt des in Fig. 2 perspektivisch dargestellten Teils,

Fig. 4

eine Explosionsdarstellung des in Fig. 2 dargestellten Teils,

Fig. 5.

in Explosionsdarstellung entsprechend Fig. 4 eine alternative Flanschbefestigung,

Fig. 6

in stark vergrößerter Schnittdarstellung die Befestigung des in Fig. 5 dargestellten Flansches im Bereich der Schraube,

Fig. 7

in perspektivischer Darstellung eine Spannringbefestigung,

Fig. 8

einen Längsschnitt durch die Bauteile im Bereich der Spannringbefestigung und

Fig. 9

eine alternative Flanschausbildung in Explosionsdarstellung ähnlich Fig. 4.

The invention is explained in more detail with reference to embodiments shown in the drawing. Show it:

Fig. 1

in a greatly simplified perspective view of a centrifugal pump with drive motor,

Fig. 2

in a greatly simplified, enlarged, partially sectioned perspective view of the transition region between the foot part and outer shell of the pump according to Fig. 1 .

Fig. 3

a longitudinal section of in Fig. 2 part shown in perspective,

Fig. 4

an exploded view of the in Fig. 2 represented part,

Fig. 5.

in exploded view accordingly Fig. 4 an alternative flange mounting,

Fig. 6

in greatly enlarged sectional view the attachment of in Fig. 5 represented flange in the region of the screw,

Fig. 7

in perspective view a clamping ring attachment,

Fig. 8

a longitudinal section through the components in the area of the clamping ring attachment and

Fig. 9

an alternative flange formation in an exploded view similar Fig. 4 ,

In the illustrated centrifugal pump 1 is a multi-stage inline pump. The centrifugal pump 1 is intended for upright operation and it has a foot part 2, to which an outer jacket 3 connects at the top, whose upper end is received by a head part 4, which also forms a motor chair for the electric drive motor 5 arranged above. The construction of in Fig. 1 The pump shown corresponds to the basic structure of such vertical multi-stage high-pressure centrifugal pumps of inline design, as they are manufactured and offered for example by the company Grundfos under the type designation CR or CRE.

The cast foot part 2 has an integrally formed therewith lower plate 6, which forms the actual foot of the centrifugal pump 1 and with which the centrifugal pump 1 rests on the ground and can be screwed via holes located in the plate 6 with the bottom. The foot part 2 has, moreover, the shape of a cylindrical tube 7 with a vertical axis, which faces away from its opposite two oppositely disposed connecting flanges 8 and 9, one of which forms the suction port and the other the pressure port of the pump 1. Via the suction connection, the liquid to be delivered passes into the foot part 2 and from there successively into the vertically adjoining pump stages, each consisting of a spiral housing and an impeller. In this case, the arrangement is such that the output of a lower volute casing is conductively connected to the input of the overlying pump stage and the output of the last, ie uppermost pump stage is connected via an annular channel with the pressure port in the foot part 2. The annular channel is defined by the peripheral sides of the Fig. 1 invisible spiral housing on the one hand and the outer shell 3 cylindrical in this area on the other hand limited. The impellers of all pump stages sit on a common shaft, which depends on the am Head part 4 of the centrifugal pump 1 arranged drive motor 5 is driven.

Although the present invention is described with reference to a vertical multi-stage centrifugal pump, it is not limited to the vertical arrangement.

The mechanical connection between the head part 4 and the foot part 2 takes place in the illustrated centrifugal pump 1 via the outer shell 3. The coaxial with the axis of rotation and shaft of the centrifugal pump arranged outer jacket 3 has the shape of a cylindrical tube, but is radially widened stepwise at the axial ends. Such an expansion consists of a flange, radially outwardly extending flange portion 10 and an adjoining parallel to the rest of the outer shell 3 extending annular shell portion 11 of larger diameter than the rest of the jacket 3. The connection between the stepped end portion of the outer shell 3 and foot part 2 based on Figures 2-4 shown, which show the axial lower end of the outer shell 3, which is connected to the foot part 2. It is understood that the axial upper end of the outer shell 3 and the connection in the head part 4 are correspondingly, but in the illustration rotated by 180 ° upwards, are formed.

The radially extending flange portion 10 at the lower end of the outer shell 3 is located at a corresponding radial, ie in the in Fig. 1 shown operating position horizontally disposed annular end face 12 of a cylindrical vertical projection 13 of the foot part 2 at. In the outer peripheral surface of the projection 13, a circumferential groove 14 is arranged, in which an O-ring 15 is incorporated. The outer peripheral surfaces of the projection 13 and the O-ring 15 form a contact surface with the inside of the shell portion 11 of the outer shell 3 sealingly abuts the projection 13.

For fixing this expanded end portion 10, 11 of the outer shell 3 on the foot part 2, a loose flange 16 is provided, which consists of two identical flange 17 in the form of flange halves. Each flange 17 engages around the outer shell 3 by about 180 °. The two flange 17 together form a closed ring with a total of six recesses in the form of vertical holes 18. These holes 18 are aligned with underlying provided with internal blind holes blind holes 19 in a cylindrical tube section 20 which is arranged coaxially to the central longitudinal axis of the pump 1 and the interior Range is continued upward through the projection 13. The blind bores 19 are embedded in an annular end face 21, which surrounds the projection 13 radially outwardly.

The loose flange 16 formed from the two flange 17 has a stepped in cross section and outwardly an upwardly tapered shape and is reinforced in the bore 18 and equipped with an upwardly flat end face. As in particular the Figures 2 and 3 can be seen, is the loose flange 16 with its flat bottom 22 on the end face 21 of the pipe section 20. The loose flange 16 also has a radial inner side 23, with which it bears against the outside of the jacket section 11. Furthermore, the loose flange 16 has a radially inwardly directed projection 24, with which it engages over the flange portion 10 of the outer shell 3. The underside of this radial projection 24 rests on the upper side of the flange portion 10. The radial inner side of the projection 24 bears against the outer casing 3 with little play. The axially expanded from flange portion 10 and shell portion 11 existing end of the outer shell 3 is thus incorporated between the projection 13 and the loose flange 16 positively and non-positively, so that a uniform application of force over the entire circumference between the foot 2 and outer shell 3 takes place. The attachment of the other axially expanded end of the outer shell 3 on the head part 4 is realized in an analogous manner.

The formed from two identical flange halves 17 loose flange 16 has, as Fig. 4 shows, two overlapping in installation position portions 25 and 26, namely an upper portion 25 and a lower portion 26. The upper portion 25, which is respectively disposed at the left-hand end of each flange portion 7 seen from the central longitudinal axis of the pump has in the installed position a Distance to the end face 21, whereas the lower portion 26, which is provided at the right-hand end, flush merges into the flat bottom 22 of the loose flange 16 and fills the space, which forms the upper portion 25 to the end face 21. Both sections 25 and 26 have an axial position in the mounting hole 18, namely the upper portion 25 has a bore 18 a and the lower portion 26 has a bore 18 b, which together form a bore 18. The sections 25 and 26 are in installation position in pairs one above the other, with their holes 18 a and 18 b aligned with the underlying blind hole 19 in the pipe section 20. The flange is fastened with screws 27, the screw heads at the top of the flange 16 circumferentially of the bores 18 rest, whereas the shafts pass through the holes 18 and engage in the threaded blind holes 19. In the region of the overlapping portions 25 and 26 thus secures the screw 27 and the flange 17 against each other from loosening. This results in a total of an annular and closed loose flange 16th

When using the Figures 5 and 6 illustrated embodiment, the outer jacket 3 is formed endwise in the same way, but there is a two-piece loose flange 16a is provided, which is composed of two identical flange halves 17a. The flange halves each consist of a semi-annular sheet metal section 28, which in the area the holes 18 is formed reinforced by also consisting of sheet metal support members 29. Both the sheet metal section 28 and the support members 29 are formed as stampings made of stainless steel and welded together for lasting connection. Again, the radially expanded end of the outer shell 3 is fixed by means of the loose flange 16 a by means of fastening screws 27 which are guided through the bores 18. Foot part side, however, a groove-like axial recess is provided, the outer wall 30 in the area around the holes 18, ie where the support members 29 come to rest, is excluded. The loose flange 16a is therefore within a groove-like recess and is surrounded and supported by the outer groove wall. The O-ring 15 for sealing is arranged in the same manner as in the above-described embodiment.

Based on FIG. 9 an embodiment is shown which substantially corresponds to the previously described, but in which the loose flange consists of a total of six identical flange 17b, which are each secured with a screw 27 in a bore 19 in the end face of the foot part 2. This flange 17b are made as stampings made of sheet metal and particularly inexpensive to manufacture.

When using the FIGS. 7 and 8 illustrated embodiment, the foot part 2 on a circumferential bead 31, which, as Fig. 8 can be seen, stepped and tapered to the top, so that the radially expanded part can be accommodated flush at the end of the outer shell 3. The radially widened part substantially corresponds to the above-described, ie it is a shell portion 11 is provided which is parallel to the outer shell 3, but has a larger diameter and a flange portion 10, but in this embodiment is not perpendicular to the outer shell, but obliquely thereto. The sealing takes place here in the bead area, and although via an O-ring 15 a, which rests against the inside of the shell portion 11.

The attachment of the components via a clamping ring 32, which has an approximately U-shaped cross-sectional shape and the peripheral bead 31 engages positively with the flared end of the outer shell 3. The clamping ring 32 is formed of sheet metal and has two reinforcing wires 33 which are incorporated into the clamping ring 32 and are secured to bearing bodies 34 which can be adjusted by means of two clamping screws 35 in their distance from each other.

To mount the clamping ring 32, the clamping screws 35 are adjusted so that the bearing body 34 have a maximum distance, d. H. the clamping ring 32 is clamped and thus can be pushed over the bead 31 and the radially expanded end of the outer shell 3. Subsequently, the clamping screws 35 are tightened until the clamping ring 32, the end of the outer shell 3 and the foot part 2 firmly beyond the bead surrounds and thus integrates the components incorporated therein.

The above-described connections between the outer casing 3 and the foot part 2 are described here only by way of example with reference to the foot part 2, they are made in the same way on the head part 4. It can also connections of different types be provided on the foot part 2 and headboard 4.

LIST OF REFERENCE NUMBERS

1

- Centrifugal pump

2

- foot part

3

- outer jacket

4

- Headboard

5

- Drive motor

6

- Plate of 2

7

- cylindrical tube of 3

8th

- flange

9

- flange

10

- Flange section

11

- jacket section

12

- face

13

- Head Start

14

- groove

15

- O-ring

15a

- O-ring

16

- loose flange

16a

- loose flange

17

- Flange parts, flange halves

17a

- Flange halves

17b

- Flange parts

18

- Drilling

18a

- Drilling in 25

18b

- Drilling in 26

19

- blind hole

20

- pipe section

21

- Face of 20

22

- flat bottom of 16

23

- Radial inside of 16

24

- radial projection

25

- upper section

26

- lower section

27

- fixing screws

28

- Sheet metal section

29

- Support parts

30

- outer wall

31

- circumferential bead

32

- clamping ring

33

- Reinforcement wires

34

- Bearing body

35

- clamping screws

Claims (20)

Centrifugal pump (1) having a plurality of pump stages, which are arranged axially between a head part (4) and a foot part (2), and with an outer casing (3), which surrounds the pump stages circumferentially, characterized in that an axial end of the outer casing (3 ) is attached to the head part (4) and the other axial end of the foot part (2), wherein the mechanical connection between the head part (4) and foot part (2) by the outer jacket (3) is formed. Centrifugal pump according to claim 1, characterized in that the outer casing (3) is widened at its axial ends. Centrifugal pump according to claim 2, characterized in that a flared axial end of the outer casing (3) by means of a cross-flange (16) on the head part (4) or the foot part (2) is attached. Centrifugal pump according to claim 2 or 3, characterized in that the axial ends of the outer casing (3) by means of the flanges (16) both force and positively on the head part (4) or on the foot part (2) are attached. Centrifugal pump according to one of claims 1 - 4, characterized in that the axial ends of the outer casing (3) are formed step-shaped widened. Centrifugal pump according to one of claims 3-5, characterized in that a flange (16) has a first contact surface (23) and a second contact surface (22), and that the first contact surface (23) at the flared axial end of the outer casing (3) abuts and the second contact surface (22) on the head part (4) or foot part (2) is applied. Centrifugal pump according to one of claims 3 to 6, characterized in that a flange is an annular loose flange (16). Centrifugal pump according to one of claims 3 to 7, characterized indicates that a flange (16) has recesses (18) for the passage of fastening means (27). Centrifugal pump according to one of claims 3 to 8, characterized indicates that at least one flange (16) consists of at least two flange parts (17). Centrifugal pump according to claim 9, characterized in that a flange (16) is formed from at least two identically shaped flange parts (17). Centrifugal pump according to claim 9 or 10, characterized in that at least two flange parts (17) overlap at their ends and in the overlapping region (25, 26) mutually aligned recesses (18a, 18b) for the implementation of fastening means (27). Centrifugal pump according to one of claims 9 to 11, characterized in that at least parts of the flange (16) made of cast metal, preferably stainless steel, are made. Centrifugal pump according to one of claims 9 to 11, characterized in that at least parts of the flange (16a) are made of sheet metal (28) which are reinforced in the region of recesses (18) by preferably consisting of sheet metal support members (29). Centrifugal pump according to one of the preceding claims, characterized in that at least one flange (16) with the head part (4) or the foot part (2) of the centrifugal pump (1) is screwed in the axial direction. Centrifugal pump according to one of the preceding claims, characterized in that on the head part (4) and / or foot part (2) a radially projecting circumferential bead (31) is provided and that the radially expanded part at the axial end of the shell (3) by means of a circumferential Clamping ring (32) is fixed to the bead (31). Centrifugal pump according to claim 15, characterized in that the clamping ring (32) has a U-shaped cross-section whose legs engage behind the radially expanded end of the jacket (3) on the one hand and the bead (31) on the other hand form fit. Centrifugal pump according to claim 15 or 16, characterized in that the bead (31) is stepped, wherein the radially widened end of the jacket (3) is incorporated flush in the gradation. Centrifugal pump according to one of the preceding claims, characterized in that the outer jacket (3) is made of sheet metal, preferably stainless steel sheet. Centrifugal pump according to one of the preceding claims, characterized in that a fluid inlet of the pump (1) on the foot part (2) or on the head part (4) and a fluid outlet of the pump (1) on the foot part or on the head part (2) are arranged, and that between an outer wall of the pump stages and the outer casing (3) is formed a channel for guiding the conveying fluid. Centrifugal pump according to one of the preceding claims, characterized in that the pump (1) is designed as an in-line pump, that fluid inlet and fluid outlet at the foot part (2) are arranged and that between an outer wall of the pump stages and the outer shell (3) a pressure channel for Guiding the fluid from the pressure side of the last pump stage is provided to the fluid outlet.

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