EP2818722A1 - 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 housings in the region of the pump stages form the outer jacket or those in which a liquid return takes place within the housing, typically to the foot part, which have an outer jacket which forms an annular channel between the outer sides of the spiral housing and the outer jacket, via which the delivery fluid flows from the head section to the foot section or possibly 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 shell are therefore fixed according to the invention, but preferably releasably attached to the foot and the headboard indirectly or directly. 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 to produce if possible, a thermally conductive connection to this.

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.

It is particularly advantageous if the outer sheath by incorporation of at least one ring form-fitting manner with the foot part and / or the Headboard is connected. The advantage of such a connection, in which the positive connection is formed by a typically open ring incorporated between the components, is that the components are quite easy to assemble, since they are tolerated without the ring diameter that they are plugged into each other. Only by interposing this ring, the actual positive connection occurs. It is particularly advantageous that the forces over almost the entire circumference are introduced uniformly from the foot part or head part to the outer shell or vice versa by the ring. The fact that the components abut each other over almost the entire circumference, at least when they are, which is likely to be the case, made of metal, a very good heat transfer between the components, so it is assumed that a uniform temperature level within the centrifugal pump can. The integrated between the components ring is advantageously not designed as a closed ring but as an open ring, so that it can be mounted by slightly expanding also on components that are larger than the inner diameter of the ring or can be incorporated into components that smaller than the outer diameter of the ring are when it is compressed accordingly. Instead of the one-piece ring and a multi-part ring can be used, which may be advantageous in terms of assembly.

Preferably, but not necessarily, the tubular outer jacket is formed of sheet metal. This 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 when z. B. results in a funnel-shaped receptacle, which allows easy mounting on the outer circumference of the pump stages. The expansion can take place radially outward or radially inward or in both directions, advantageously by plastic Shaping, such as rolling, deep drawing, upsetting, flanging or the like.

The attachment of the outer shell in the head part or in the foot part is particularly advantageous if at least partially circumferential radially inwardly directed projection is provided on the foot part and / or on the head part. This projection is expediently designed so that the axial, optionally flared, end of the outer shell is still just passed and only after integration of the ring of the desired fit, in particular in the axial direction occurs. Such a projection can, if the head part or the foot part are made of cast iron, be provided directly. However, it is also conceivable to form the projection by a separate, single or multi-part, annular component which is fixed to the head or foot, is typically screwed. Thus, such a projection may be 360 ° circumferentially formed when it is formed by a flange which is screw-mounted on the head part or the foot part typically on an axial end face.

Such a flange may be formed in one piece, but also in several parts. In the latter case, it is advantageous if the individual flange parts are identical, z. B. by two identical flange halves.

Advantageously, the ring, which produces the positive connection between the head part and outer shell or foot part and outer shell, be formed in several parts. Then it is appropriate to divide the ring so that all parts are identical, z. B. to provide two identical ring halves.

In addition to any grooves for the incorporation of O-rings between the outer shell and headboard or outer shell and foot, the outer shell advantageously at least one end of a circumferential and radially outwardly open groove, which serves for the integration of the ring, with which the positive connection between the outer shell and headboard or outer shell and footboard is made. If the outer sheath is formed from sheet metal, such a groove may be formed by a molding in this area.

In addition, head and foot also advantageously have a circumferential, but radially inwardly open groove for receiving the ring, which is advantageously arranged so that it is opposite in the installed position of the groove at the end of the outer shell or from the outer shell to the headboard or footboard seen in front of the radially expanded end of the outer shell is arranged. This arrangement ensures that the ring to be incorporated therein holds the flared end of the outer shell in a form-fitting manner within the head part or foot part. Such a groove is formed either in a casting from the outset, which is inexpensive, or possibly also made by machining. Finally, such a groove can also be formed by screwing a flange to an axial side of the head or foot part. It is particularly advantageous if means for radially displacing the ring are provided on the head part and / or on the foot part. By such means it is possible to move the already incorporated between the components ring from a non-locking to a locking position or vice versa. Here, radial displacement in the sense of the invention not only a spatial displacement of the ring or ring parts to understand, but in particular a change in the diameter of the ring by upsetting or widening. The latter requires, however, that the ring is at least open or multi-part design.

Such means for shifting can be formed, for example, by threaded head screws, preferably radially arranged on the head part and / or on the foot part, which are accessible from the outside and in each case in a threaded bore are guided, which opens into the groove open inwardly. With such comparatively simple screws, a ring inserted in the inwardly open groove can be displaced or compressed radially inwards in order to engage in the opposite groove of the outer jacket or to protrude at least so far against the outer jacket that the widening behind it is held in a form-fitting manner is. If, which is advantageous, the ring is designed as an open spring ring, then disassembly can be done by unscrewing these screws, since the ring then springs back automatically to its original position.

If, which is advantageous, an open spring ring is provided as a ring for positive connection between the head and outer shell or between the foot and outer shell, then the ring diameter can be changed only by the fact that the distance between the ring ends is adjusted. It can therefore be advantageously provided means for adjusting this distance on the headboard and / or footboard to make the positive connection with a few simple steps and optionally also to solve again.

According to an advantageous embodiment of the invention, an auxiliary ring is provided, with which the ring can be converted into its locking position, wherein means for moving the auxiliary ring are provided on or in the foot part or headboard. The arrangement of such an auxiliary ring has the advantage that the actual ring, which is provided for attachment between the head and outer shell or foot and outer sheath is not punctually loaded by screws or similar body, but only this auxiliary ring, which, however, hardly forces must record. The auxiliary ring thus serves exclusively to bring the ring into its locking or unlocking position and to hold it there.

Preferably, interlocking means are provided at the axial end of the outer jacket, which hold the outer jacket against rotation on the foot part or on the head part. Such positive locking means can be provided by a tongue and groove arrangement in the region of the widened part on the outer circumference of the outer jacket and on the corresponding inner side of the corresponding receptacle of the head part or foot part. For example, in the widened part of the outer jacket, axially parallel recesses can be distributed over the circumference, which engage in corresponding projections in the associated receptacle from the head part or foot part. These components provide a rotationally fixed connection between the headboard and outer shell or foot and outer shell.

Fig. 1

in stark vereinfachter perspektivischer Darstellung eine Ansicht eines erfindungsgemäßen Kreiselpumpenaggregates mit unterschiedlichen Befestigungen von Kopfteil und Fußteil,

Fig. 2

in perspektivischer Darstellung eine Ausführung der Befestigung eines axialen Außenmantelendes am Fußteil,

Fig. 3

die Verbindung der Fig. 2 in Explosionsdarstellung,

Fig. 4

einen Längsschnitt durch die Verbindung nach Fig. 2,

Fig. 5

in stark vergrößerter Darstellung die Einzelheit V in Fig. 4,

Fig. 6

eine alternative Befestigung in Darstellung nach Fig. 5,

Fig. 7

eine weitere Ausführung in Darstellung nach Fig. 5

Fig. 8

ein weiteres Ausführungsbeispiel in Darstellung nach Fig. 2,

Fig. 9

die Ausführung nach Fig. 8 in Explosionsdarstellung,

Fig. 10

einen Querschnitt mit drei verschiedenen Stellungen des Ringes,

Fig. 11

die Verbindung gemäß Fig. 10 in entriegelter Stellung in Darstellung entsprechend Fig. 5,

Fig. 12

ein weiteres Ausführungsbeispiel in Explosionsdarstellung entsprechend Fig. 3,

Fig. 13

die Verbindung im zusammengefügten Zustand in Darstellung entsprechend Fig. 5,

Fig. 14

ein anderes Ausführungsbeispiel der Befestigung des Außenmantels im Fußteil in Darstellung entsprechend Fig. 2,

Fig. 15

einen Längsschnitt der Ausführung gemäß Fig. 14 in Darstellung entsprechend Fig. 4,

Fig. 16

die Verbindung nach den Figuren 14 - 15 in verriegelter Stellung in Darstellung entsprechend Fig. 5,

Fig. 17

die Verbindung nach den Figuren 14 - 15 in entriegelter Stellung in Darstellung entsprechend Fig. 5,

Fig. 18

ein weiteres Ausführungsbeispiel in Explosionsdarstellung entsprechend Fig. 3,

Fig. 19

die Verbindung gemäß Fig. 18 in Darstellung nach Fig. 5 mit eingeführtem Werkzeug,

Fig. 20

die Verbindung nach Fig. 18 in verriegelter Stellung in Darstellung entsprechend Fig. 5 und

Fig. 21

die Verbindung nach Fig. 18 in entriegelter Stellung in Darstellung entsprechend Fig. 5.

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 view of a centrifugal pump assembly according to the invention with different fasteners of the headboard and footboard,

Fig. 2

a perspective view of an embodiment of the attachment of an axial outer shell end to the foot part,

Fig. 3

the connection of the Fig. 2 in exploded view,

Fig. 4

a longitudinal section through the connection after Fig. 2 .

Fig. 5

in a greatly enlarged view the detail V in Fig. 4 .

Fig. 6

an alternative attachment in representation after Fig. 5 .

Fig. 7

another embodiment in illustration after Fig. 5

Fig. 8

a further embodiment in illustration according to Fig. 2 .

Fig. 9

the execution after Fig. 8 in exploded view,

Fig. 10

a cross section with three different positions of the ring,

Fig. 11

the connection according to Fig. 10 in unlocked position in representation accordingly Fig. 5 .

Fig. 12

a further embodiment in exploded view corresponding Fig. 3 .

Fig. 13

the connection in the assembled state in representation accordingly Fig. 5 .

Fig. 14

another embodiment of the attachment of the outer shell in the foot part in illustration accordingly Fig. 2 .

Fig. 15

a longitudinal section of the embodiment according to Fig. 14 in representation accordingly Fig. 4 .

Fig. 16

the connection to the FIGS. 14-15 in locked position in representation accordingly Fig. 5 .

Fig. 17

the connection to the FIGS. 14-15 in unlocked position in representation accordingly Fig. 5 .

Fig. 18

a further embodiment in exploded view corresponding Fig. 3 .

Fig. 19

the connection according to Fig. 18 in representation after Fig. 5 with inserted tool,

Fig. 20

the connection after Fig. 18 in locked position in representation accordingly Fig. 5 and

Fig. 21

the connection after Fig. 18 in unlocked position in representation accordingly Fig. 5 ,

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 wheels of all pump stages sit on a common shaft, which is driven by the head part 4 of the centrifugal pump 1 arranged drive motor 5.

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

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 for attachment in the head part 4 and in the foot part of the second formed widened at the axial ends. The variants described below, in each of which the axial upper end of the foot part and the lower end of the outer shell 3 engaging therewith are shown, can be used in the same way for the connection between the head part and outer shell. Advantageously, the same types of connections and components are selected for both connections. However, this is not absolutely necessary, it may optionally be different compounds, as exemplified in Fig. 1 is shown, where the connection between the foot part and outer shell of the basis of FIGS. 9 to 11 described, whereas the connection between the headboard and outer shell of the basis of FIGS. 12 to 13 corresponds described.

When using the FIGS. 3 to 5 illustrated embodiment, the axial end of the outer shell 3 is expanded radially outward. The outer shell 3 formed from sheet metal is compressed there to a circumferential bead 10. The tubular part 7 of the foot part 2 is stepped cylindrical to its axial upper end. It has an inner part 11 which limits the circumferential axial surface 12 inwards. On the annular surface 12 holes 13 are arranged distributed, which serve to receive fastening screws 14, which serve to define a flange 15 having an annular cylindrical shape with an inwardly radially projecting bead 16. As in particular in Fig. 5 is visible, serves the superior inner part 11 for guiding the axial end of the outer shell 3 on the inside. There is also a circumferential groove for an O-ring 17 is provided, with which the outer shell 3 is sealed against the inner part 11 and thus against the foot part 2. The outer circumference of the bead 10 at the end of the outer shell 3 is slightly smaller than the inner circumference of the bead 16 on the flange 15, so that the flange 15 can be pushed over the end of the outer shell.

In order to achieve a positive connection between these components, a ring 18 is provided. This ring 18 is, as in particular from Fig. 3 seen, open, so that after the flange 15 has been pushed over the end of the outer shell 3, it is so far increased in diameter by bending resiliently that it can be pushed over the bead 10. This ring 18 then springs back and frictionally engages the cylindrical part of the outer shell 3 on the outside. Now, if the flange 15 is fastened by means of the screws 14 in the holes 13 and thus on the foot 2, this ring 18 is pushed between the beads 10 and 16, as it is in Fig. 5 is shown. The beads 10 and 16 have for this purpose corresponding inclined surfaces, so that the ring 18 create a force fit between these beads can. This ring 18 now forms a positive connection between the flange 15 and the flared end of the outer shell 3 and thus defines this form-fitting and non-positive in the foot part 2.

It can be seen that this results in a very uniform application of force over the entire circumference. Also lie through the ring 18, which is formed of spring steel, the metallic flange 15, the outer shell formed from sheet metal shell 3 and the cast foot part 2 closely and thermally conductive to each other, so that they always have about the same temperature level during operation.

The release of the connection takes place in the reverse direction, d. H. after loosening the screws 14, the flange 15 is first lifted up until the ring 18 is accessible. This is then bent, pushed over the bead 10 at the end of the outer shell 3, after which the outer shell 3 can be removed from the foot part 2 upwards.

In the case of Fig. 6 illustrated embodiment, the axial end of the outer shell 3 is widened radially inwardly and there has a circumferential bead 19 which rests against the inner part 11 under inclusion of a sealing this component O-ring 17. The outer casing 3 is cylindrical on its outer side to the end, but has a circumferential in cross-section semicircular groove 20 which is provided for the integration of the ring 18, the positive connection between the end of the outer shell 3 and the foot part 2 with the flange 21st forms, which also has a radially inwardly projecting and encircling bead 22 which, however, in contrast to the bead 16 extends directly to the outside of the outer shell 3. Outer casing side of the ring 18 is positively fixed in the groove 20, flange side by the bead 22nd

In the case of Fig. 7 illustrated embodiment, the outer shell 3 is formed widened at its axial end 23, but not compressed, as in the embodiments described above. The outer casing 3 therefore also has essentially the same material thickness in the widened region 23 as in the remaining region. This flared end 23 of the outer sheath 3 is located in a circumferential groove 24 in the axial surface 12. Also, the transition between the groove 24 and the inner part 11, which supports the axial end of the outer sheath 3 radially inwardly, adapted accordingly. The seal between the outer shell 3 and the foot also takes place here by an O-ring 17, which lies in a circumferential groove on the outer circumference of the inner part 11 and which rests against the inside of the outer shell 3. A flange 25 is fastened by means of screws 14 in holes 13 under inclusion of the ring 18 and thus defines the outer shell 3 in the foot part 2. The flange 25 here has an outwardly sloping shape. On the inside, it has a bead 26, with which it holds the ring 18 positively but also non-positively.

In all the above embodiments, the assembly of the compound takes the form that first the respective flange is pushed over the axial end of the outer shell, after which the ring 18 is pushed onto this end and the axial end is brought into its intended position in the foot part 2. Then, the flange is fastened by means of the screws 14 in the holes 13, after which the connection is positive and non-positively fixed. The release takes place in reverse order.

When using the FIGS. 8 to 11 described embodiment, an existing also made of spring steel ring 27 is provided which has a rectangular cross-section and whose ends are bent radially outwards. It is therefore also an open ring, the ends 28 for better force introduction radially outward are bent. The axial end of the outer shell 3 is also widened, but only radially outward. It is therefore formed at the end of the outer shell 3 a rectangular in cross-section and radially outwardly projecting bead 29. The upper axial end of the foot part 2 has an inner part 11 which supports the outer casing 3 on the inside. From a footprint 30, the inner part 11 protrudes a cylindrical outer part 31, which has an inner circumferential rectangular groove 32 which is open radially inwardly and whose shape corresponds to the cross-sectional shape of the ring 27. The cylindrical outer part 31 has on one side a projecting flattened portion 33, in which two approximately tangentially arranged threaded holes 34 are mounted, in which screws 35 sit, the ends of which impinge in a free space 36 formed there on the ends 28 of the ring 27, and Although the way that when screwing the screws 35 in the foot part 2, the ends 28 are moved towards each other, whereas during the removal of these drift apart by spring force of the ring 28.

The ring 27 is in Fig. 10 shown in three different positions, a position A, in which the ring 27 has its smallest diameter and the ends 28 are close to each other, a position B, in which the ring 27 has its largest diameter and thus the ends 28 have the greatest distance from each other and a position C between the positions A and B. In the position A, the ring 27 is maximally tensioned, almost relaxed in the position B.

For assembly, the ring 27 is first inserted from above into the open-topped annular opening between the inner part 11 and the cylindrical outer part 31, up to the level of the groove 32. In this position A, the ring 27 is held by one of the ends 28 grasping and holding in this position tool or a dedicated mounting bracket. Once the ring 27 is in the region of the groove 32, the mounting bracket is removed so that the ring 27 springs back into its position B with not yet screwed set screws 35, in which the ring 27 is completely within the groove 32 and the ends 28 are arranged in the free space 36. Then, the flared end of the outer shell 3 is also introduced with its bead 29 from above into the foot part 2 until the end face comes into contact with the contact surface 30. Then the results in Fig. 11 illustrated constellation. In order to connect the components positively with each other, the screws 35 are screwed to the predetermined position in which the ring 27 occupies the position C, that is located with one part within the groove 32 and with another part within the open space upwards is located and thus blocked the bead 29 at the end of the outer shell 3 against retraction from the gap upwards.

To open the connection, turn the adjusting screws 35 until the ring 27 returns to position B, d. H. is completely in the groove 32, so that the outer shell 3 can be pulled out of the foot part 2.

How out Fig. 9 can be seen, 32 vertical projections 37 are arranged on the inside of the cylindrical outer part 31 below the groove, which in corresponding vertical recesses (41 in Fig. 12 ) engage in the bead 29 of the outer shell and thus form a positive rotation lock between the outer shell 3 and foot part 2.

The basis of the FIGS. 12 and 13 illustrated embodiment differs from the above by the fact that a ring 38 is provided, which has the same rectangular cross-section as the ring 27, but is not bent radially at its ends, but is designed as an open spring ring. Moreover, the cylindrical outer part 31 does not have the flattened part 33 with the adjusting screws 35, but a plurality of radial threaded holes 39 which pass through the cylindrical outer part 31 and open at the bottom of the groove 32.

In this embodiment, the adjustment of the width of the ring 38 via radial screws 40, which sit in the threaded holes 39 and with which the ring 38 from the in Fig. 11 shown position in which it lies completely in the groove 32 in the in Fig. 13 shown position is transferred, in which the ring 38 is approximately halfway inside the groove 32 and protrudes radially inwardly and thus secures the bead 29 positively against dodging upwards. Also in this embodiment, projections for rotational security between the outer shell 3 and the foot part 2 are provided. Clearly visible are the corresponding recesses 41 in the bead 29.

When using the FIGS. 14 to 17 illustrated embodiment, the flared end 42 of the outer shell 3 is expanded radially inwardly, thereby forming a part-circular cross-section groove 43 for the integration of a ring 46 round cross-section. The ring 46 is a partially open spring ring and similar to that described above. The axially upper end of the foot part 2 here has a circumferential and upwardly open groove 44, which is provided for receiving the free end of the outer shell 3. Again, a one-sided superior cylindrical outer part 45 is provided, which has a lower circumferential groove with an O-ring 17 for sealing, here on the outside of the outer shell 3.

The cylindrical outer part 45 has a radially inwardly directed groove 47, which is arranged in the installed position of the groove 43 opposite. Furthermore, the cylindrical outer part 45 in its upper side a plurality of threaded holes 48, in which threaded screws 49 sit, which are arranged axially parallel to the impeller axis are. These threaded holes 48 open at the groove bottom of a within the radial groove 47 upwardly extending groove 50 which is provided for receiving an auxiliary ring 51.

The ring 46 is dimensioned in this embodiment, that it rests due to its residual stress in the expanded position within the radial groove 47, as described with reference to Fig. 17 is shown. In this position, the axial end of the outer shell 3 can be inserted into the foot part 2 until the end comes into abutment in the groove 44. In this position, the screws 49 are screwed, whereby the auxiliary ring 51, which displaces due to its smaller diameter relative to the ring 46, this radially inward, so that this in Fig. 16 illustrated locking position occupies, in which the ring 46 is disposed to one half in the groove 43 in the flared end 42 of the outer shell 3 and the other in the radial groove 47 of the cylindrical outer part 45. The auxiliary ring 51 is arranged directly next to it, so that the ring 46 is held positively in this position.

To release the connection, the screws 49 are first to be solved. To the auxiliary ring 51 from its blocking position ( Fig. 16 ), circumferentially elongated holes 52 are provided in the cylindrical outer part 45, which open at the bottom of the radial groove 47. Through these slots, an auxiliary instrument, such as a screwdriver can be introduced from the outside, with which the auxiliary ring 51 can be levered upwards, after which the ring 46 springs up and releases the positive connection with the widened end 42.

Based on FIGS. 18 to 21 is a further embodiment variant shown, the outer shell side corresponds to the above, but is formed differently on the Fußteilseitig. Fußteilseitig a footprint 53 is provided, which is about half the width of the hollow cylindrical Component 7 extends. From this upwardly extends a cylindrical outer part 54, which has a groove 43 in the installed position opposite radially inwardly open groove 55, and a subsequent thereto subsequent circumferential and groove 55 toward the open groove 56. In addition, vertical holes 57 are provided which open into the radial groove 55 and aligned with the groove 56.

In the upwardly open groove 56 a cross-sectionally oval auxiliary ring 58 is inserted, after which the ring 46 is moved into the radial groove 55, in which it rests widened by residual stress. In this position, the flared end 42 of the outer shell 3 is inserted into the foot part 2 until it rests on the contact surface 53. Then the results in Fig. 21 shown position. For locking the auxiliary ring 58 is now levered by means of an auxiliary instrument 60 by radially provided in the cylindrical outer part 54 slots 59 upwards. Since the auxiliary ring 58 has a smaller diameter than the ring 46 in the upper region, it displaces it inwards. Once the auxiliary ring 58 in the in Fig. 20 shown, the ring 46 has been brought outwardly supporting position in which the ring 46, the components 2 and 3 locked to each other, are inserted into the slots 59 from the outside plugs 61 which remain non-positively in these slots and their ends the auxiliary ring 58th supported at the bottom and thus secure against displacement in the ring 46 releasing position.

To release the connection, the plugs 61 are removed by inserting a corresponding tool from the oblong holes 59. Then, with a mandrel through the holes 57 of the auxiliary ring 58 pressed down to the ring 46 again in Fig. 21 shown unlocking position occupies, in which the outer shell 3 can be removed from the foot part 2.

LIST OF REFERENCE NUMBERS

1

rotary pump

2

footboard

3

outer sheath

4

headboard

5

drive motor

6

Plate of 2

7

cylindrical tube of 3

8th

flange

9

flange

10

bead

11

inner part

12

area

13

drilling

14

screw

15

flange

16

bead

17

O-ring

18

ring

19

Bead ( Fig. 6 )

20

Groove ( Fig. 6 )

21

Flange ( Fig. 6 )

22

Bead ( Fig. 6 )

23

expanded end ( Fig. 7 )

24

Groove ( Fig. 7 )

25

Flange ( Fig. 7 )

26

Bead ( Fig. 7 )

27

Ring ( Fig. 8-11 )

28

Ends of the ring ( Fig. 8-11 )

29

Bead ( Fig. 8 - 11 )

30

Footprint ( Fig. 8 - 11 )

31

cylindrical outer part ( Fig. 8-11 )

32

Groove ( Fig. 8-11 )

33

flattened part ( Fig. 8-11 )

34

Threaded holes ( Fig. 8-11 )

35

Adjusting screws ( Fig. 8-11 )

36

Free space ( Fig. 8-11 )

37

Head Start ( Fig. 8-11 )

38

Ring ( Fig. 12-13 )

39

Threaded holes ( Fig. 12-13 )

40

Screws ( Fig. 12-13 )

41

Recesses ( Fig. 12 - 13 )

42

expanded end of 3 ( Fig. 14-17 )

43

Groove in 42 ( Fig. 14-17 )

44

Groove ( Fig. 14-17 )

45

cylindrical outer part ( Fig. 14-17 )

46

Ring ( Fig. 14-17 )

47

radial groove ( Fig. 14-17 )

48

Threaded hole ( Fig. 14-17 )

49

Screws ( Fig. 14-17 )

50

Groove in 47 ( Fig. 14-17 )

51

Auxiliary ring ( Fig. 14 - 17 )

52

Long holes ( Fig. 14 - 17 )

53

Footprint ( Fig. 18-21 )

54

cylindrical outer part ( Fig. 18-21 )

55

radial groove ( Fig. 18-21 )

56

upwardly open groove ( Fig. 18-21 )

57

Holes ( Fig. 18-21 )

58

Auxiliary ring ( Fig. 18 - 21 )

59

Long holes ( Fig. 18 - 21 )

60

Auxiliary tools ( Fig. 18-21 )

61

Plug ( Fig. 18-21 )

Claims (16)

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 positively connected to the foot part and / or the head part by incorporation of at least one ring (18; 27; 38; 46). Centrifugal pump according to claim 2, characterized in that the outer casing (3) is formed radially widened at at least one end. Centrifugal pump according to claim 1 or 2, characterized in that the foot part (2) and / or the head part (4) has an at least partially circumferential radially inwardly directed projection (16; 22; 26). Centrifugal pump according to claim 4, characterized in that the inwardly directed projection (16; 22; 26) is formed by a flange (15; 21; 25) screwed to the head part (4) or to the foot part (2). Centrifugal pump according to claim 5, characterized in that the flange is designed in several parts, preferably two identical flange halves. Centrifugal pump according to one of the preceding claims, characterized in that the ring (18; 38; 46) is multi-part, preferably has two identical ring halves. Centrifugal pump according to one of the preceding claims, characterized in that the outer casing (3) is provided at least at one end with a circumferential groove (43) which is open radially outwards. Centrifugal pump according to one of the preceding claims, characterized in that in the foot part (2) and / or head part (4) has a circumferential and radially inwardly open groove (32; 47; 55) for the integration of the ring (27; is. Centrifugal pump according to claim 9, characterized in that the radially inwardly open groove (32; 47; 55) in installation position of the groove (43) opposite to the end of the outer shell or from the outer shell (3) to the head part (4) or to the foot part ( 2), is arranged in front of the radially expanded end of the outer jacket (3). Centrifugal pump according to one of the preceding claims, characterized in that on the head part (4) and / or on the foot part (2) means (35; 40; 49; 59; 60) are provided for preferably radially displacing the ring (27; 38; 46) are. Centrifugal pump according to one of the preceding claims, characterized in that on the head part (4) and / or on the foot part (2) externally accessible preferably radially arranged threaded screws (40; 49) are provided, each in a threaded bore (39; 48) out are, which opens in the inwardly open groove (32; 47). Centrifugal pump according to one of the preceding claims, characterized in that the ring (18; 27; 38; 46) is designed as an open spring ring and that means are provided on the head part (4) or on the foot part (2) to adjust the spacing of the ring ends , Centrifugal pump according to one of the preceding claims, characterized in that an auxiliary ring (51, 58) is provided, with which the ring (46) can be converted into its locking position and that means for moving the auxiliary ring (51, 58) on or in the foot part (2) or head part (4) are provided. Centrifugal pump according to one of the preceding claims, characterized in that in the head part (4) and / or in the foot part (2) recesses (52; 59) are provided, through which the auxiliary ring (51; 58) is accessible to this in its unlocking To move position. Centrifugal pump according to one of the preceding claims, characterized in that at the axial end of the outer casing (3) positive locking means (41) are provided, which rotatably hold the outer shell (3) on the foot part (2) and / or on the head part (4).

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