EP2233748A1 - Multi stage centrifugal pump - Google Patents

Abstract

The pump (2) having a shaft (12) rotatably mounted in a housing (3). A set of impellers (8) is clamped between an abutment ring and a free end of the shaft, where the abutment ring is arranged in a transition region of the shaft. A stationary axial face seal ring is arranged in the housing. A rotating axial face seal ring is arranged on the shaft. Positive-fit unit and helical compression spring are arranged between a motor-side spring holder and an impeller-side spring holder, where the motor-side spring holder is provided in engagement with the stationary ring.

Description

The invention relates to a multi-stage centrifugal pump according to the features specified in the preamble of claim 1.

Single or multi-stage centrifugal pumps of the type in question are state of the art. The present invention particularly relates to such multi-stage centrifugal pumps, the drive shaft lying, d. H. is arranged horizontally in normal operation. Such centrifugal pumps, as they belong to the prior art, are offered for example by the company Grundfos in the series CH and CHN. These pumps have a pump housing with a rotatably mounted therein shaft, which at its motor end has at least one cylindrical portion and then pump side then a splined portion on which rotatable wheels are arranged, clamped between a seated on the shaft stop ring and the free end of the shaft are. Such pumps are driven by an electric motor whose drive shaft is rotatably connected to the bearing in the pump housing, the wheels bearing shaft and is connected via screw to the pump.

In order to permanently seal the fixed housing part of the pump with respect to the rotating shaft, a mechanical seal is provided, which is incorporated between the cylindrical shaft portion and the pump housing. This mechanical seal has a stationary and sealed relative to the pump housing stationary seal ring and arranged on the shaft and sealed against the shaft rotating seal on each other have sliding and each other Federkraftbeaufschlagte Axialdichtflächen. For applying the spring force, a spring is provided, which is arranged between two spring holders and these oppositely applied with a compressive force.

These known centrifugal pumps have proven themselves, in particular the above-described mechanical seal. However, the above-described arrangement requires a relatively large axial length.

Against this background, the present invention has the object, a generic centrifugal pump in such a way that their axial length can be reduced in otherwise the same hydraulic performance. In addition, the design should be designed so that it can be produced as inexpensively as possible in mass production.

This object is achieved according to the invention by the features specified in claim 1. Advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the drawings.

The multistage centrifugal pump according to the invention has a pump housing and a shaft rotatably mounted therein, which at its motor end at least one cylindrical portion and then pump side has a splined portion, are rotatably mounted on the wheels, between a seated on the shaft stop ring and the free Shaft end are clamped. Between the cylindrical shaft portion and the pump housing, a mechanical seal is incorporated, which arranged in the pump housing and sealed in contrast stationary sliding ring and arranged on the shaft and the opposite having sealed rotating seal ring. These slip rings slide with their oppositely directed axial surfaces on each other and are spring-loaded. To apply the spring forces two spring holders are provided, between which compression spring means are held. According to the invention, the stop ring is arranged in the transition region of the shaft between the cylindrical portion and the spline portion and arranged between the spring holders. In addition, positive locking means are provided between the spring holders, which are effective at least in the intended direction of rotation of the shaft, ie in working direction.

This solution according to the invention utilizes the otherwise unused transition region of the shaft for the arrangement of the stop ring, ie the difference in diameter between the groove base from the splined shaft section to the cylindrical section. At the same time, it lies between the spring holders, ie a space that otherwise usually remains unused constructively. As a result, the axial length of the pump can be significantly reduced. In order to make the shaft co-rotating with the shaft without loading its opposite the shaft seal, interlocking means between the spring holders are provided according to the invention, which rotates the shaft from the splined shaft portion to the pump-side spring holder and the interlocking means to the motor-side spring holder and from there transferred to the rotating seal ring.

Advantageously, the stop ring is held in a form-fitting manner on the shaft, at least in the axial direction toward the motor-side shaft end. Such a form-fitting mounting is particularly easy to implement in particular when the cylindrical shaft portion has a larger diameter than at the groove bottom of the spline portion, which is provided according to a development of the invention. Moreover, the cylindrical shaft portion should be the same or equal larger diameter than the spline portion outside of the grooves to allow mounting of the seal rings from the pump side. In this case, the stop ring is suitably held not only in the axial direction positively on the shaft, but also in the direction of rotation. For this purpose, the stop ring on its inside a corresponding profiling, with which it is positively engaged with the spline of the spline shaft section. In mass production, the profiling of the shaft to the spline profile is advantageously carried out by force deformation, ie by forming the shaft by means of a die. Since this method is also subject to comparatively small tolerances in the axial direction, the stop ring can be mounted at a defined location on the shaft, by positive locking, which is particularly advantageous.

In order to ensure a large-scale system and thus to be able to absorb high forces, the stop ring is provided on its inside with inclined surfaces, which is located on the at least one corresponding inclined surface of the shaft in the transition region of the shaft between the cylindrical portion and according to an embodiment of the invention support the spline shaft section. These inclined surfaces can be achieved on the shaft side in a simple manner by the above-described forming process. Stop ring side these are expediently formed as well as the spline, for example by forging. Alternatively, here also a cast component or a machined component can be used.

The axial length of the centrifugal pump can be further reduced in that the spring means are arranged and designed so that they overlap at least partially the stop ring and the rotating seal ring. This reduces the axial length of the mechanical seal so that it corresponds approximately to the axial length of the rotating seal ring plus the axial length of the stop ring.

At the same time then the stop ring can correspond approximately to the inner diameter of the spring and thereby absorb the forces of the inclined surface of the transition region without deforming. This can be done advantageously by providing a helical compression spring as a spring means. Such helical compression springs provide sufficient design with appropriate design, are inexpensive to manufacture and sufficient with appropriate dimensions for applying the required forces.

The construction of the invention is preferably designed so that the mechanical seal is not mounted from the motor side, but from the pump side of the shaft. In order to facilitate the assembly, in particular to ensure that the stop ring remains in its intended position, is provided according to a development of the invention to provide positive locking means on the spring holders, with which these under bias of the spring means for the purpose of assembly at least in one direction axially fixed to each other. There are thus biased by these positive locking means of the spring holder during assembly, the spring means and practically put out of action in their effect. Only when the assembly is completed and the last pump impeller is placed on the shaft and clamped, these positive locking means are released to apply the necessary axial pressure on the mechanical seal, in particular the rotating seal ring. For this purpose, a kind of bayonet connection can be provided between the spring holders according to the invention. It when the bayonet connection is designed so that the locking takes place counter to the working direction of rotation or that upon movement of the shaft in working direction, the lock is released automatically is particularly advantageous. Such an arrangement has the advantage that no separate step for releasing the interlocking means between the spring holders is required, but that they automatically solve during start-up of the centrifugal pump in working direction.

In order to arrange the spring means, in particular the helical compression spring so that it surrounds the rotating seal ring, according to an advantageous embodiment of the invention, the slide ring-side spring holder is formed cranked so that it circumferentially engages over the rotating seal ring with its bent portion, in this cross-part the preferably helical compression spring is guided.

In order to non-rotatably connect the impeller-side spring holder with the shaft, at least one driver engaging in the splined shaft profile is provided on the impeller-side spring holder. Advantageously, the impeller-side spring holder on a central recess which is profiled according to the spline profile, so that it sits positively over its entire circumference on the shaft.

Also, the stationary seal ring has positive locking means, which are preferably mounted on its outer periphery to secure it in the pump housing against rotation. When attaching the positive locking means on the outer circumference they are easy to assemble, without a hidden orientation is required, as is the case for example in the arrangement of positive locking means on an axial side.

Advantageously, according to a development of the invention, the impeller-side spring holder is pot-shaped and has the sliding ring-side spring holder open recesses in the peripheral wall, engage in the radial projections of the slip ring side spring holder. About these open recesses reach the radial projections of the sliding ring-side spring holder in the region of the impeller-side spring holder, which then positively entrains them in the direction of rotation.

In order to prevent that, in particular, when the aforementioned components are formed from sheets, wear of the contact surface in the recess occurs, the edges of the recesses in the engagement region of the projections are formed reinforced according to an embodiment of the invention. Such a reinforcement can be effected particularly simply by enlarging the support surface, which can happen, for example, in the case of a sheet-metal component in that a section is bent so that not the sheet edge, but the flat side forms the bearing surface. In this way, a "digging" of a projection in the support surface is effectively prevented.

Fig. 1

eine dreistufige Kreiselpumpe mit Antriebsmotor im Längsschnitt,

Fig. 2

die Gleitringdichtung mit Federhaltern, Feder und Haltering in perspektivischer Explosionsdarstellung und

Fig. 3

die den Gleitring und dessen Anbringung betreffende Einzelheit der Fig. 1 in stark vergrößerter Schnittdarstellung.

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

Fig. 1

a three-stage centrifugal pump with drive motor in longitudinal section,

Fig. 2

the mechanical seal with spring holders, spring and retaining ring in a perspective exploded view and

Fig. 3

the detail of the sliding ring and its attachment Fig. 1 in greatly enlarged sectional view.

The basis of Fig. 1 shown in longitudinal section centrifugal pump unit has an electric drive motor 1, to which a three-stage centrifugal pump 2 is mounted, which drives the motor 1. The centrifugal pump 2 has a pump housing 3, which is lined or formed with stainless steel sheet. The frontal housing parts 4 and 5, so the outer support flange 4 and the inner connecting flange 5 are formed as castings, whereas the housing shell 6 is formed of sheet metal. The delivery liquid enters through a suction flange 7 provided in the support flange 4. From there, the liquid to be delivered passes via three pump stages with impellers 8 into an annular space formed between the pump stages and the jacket 6 and from there to a radially outgoing pressure port 9 on the jacket. 6

The connecting flange 5 forms in this embodiment, the frontal end of the engine and carries a bearing 10, with which the motor shaft 11 is mounted in this area. The motor shaft 11 is fixedly connected to the pump shaft 12, on which the wheels 8 sit and which is sealed by means of a mechanical seal 13 with respect to the connecting flange 5, which is penetrated by the pump shaft 12.

The mechanical seal 13 has a housing-fixed, ie not co-rotating, stationary seal ring 14 which is sealed by means of an O-ring 15 relative to the pump housing 3, in particular the sheet metal lining in the region of the connecting flange 5. The stationary seal ring 14 has two projecting beyond the otherwise circular shape lugs 16 which are arranged diametrically and bear against a sheet metal portion of the lining, not shown in the drawing, which holds the seal ring 14 rotatably and also ensures that carried by the liquid conveyed Gas does not accumulate in the area of the sliding ring, but is discharged with the delivery liquid. In contrast, axially offset to the pump facing axial surface 17 in the form of an annular surface which forms the fixed sliding surface of the seal. On this sliding surface 17 slides in Fig. 2 invisible axial surface 18 (see Fig. 3 ) of a rotating seal ring 19, which is sealed by means of an O-ring 20 against the shaft 12 on which it sits and with which it rotates. The pump shaft 12 is cylindrical in the region of the sliding rings 14, 19 and forms a cylindrical portion 21 there. To the wheels 8 towards the shaft 12 is formed tapered and goes there in a splined shaft profile. On the spline section 22, the wheels 8 of the pump sit positively.

To press the axial surfaces 17 and 18 of the slip rings 14 and 19 with the required force in operation on each other, a helical compression spring 23 is provided, which is arranged between two spring holders 24 and 25. The motor-side spring holder 24 is formed cranked. It is formed in the direction of rotation of the shaft 12 positive reception of the rotating seal ring 19 and surrounds this circumferentially almost completely, as from Fig. 3 is apparent. The motor-side spring holder 24 closes with little play on the cylinder portion 21 of the shaft 12. It initially extends radially, and then about 90 ° to the motor 1 toward bending in the direction of rotation of the shaft positive inclusion of the rotating seal ring 19 and the O-ring 20. It then runs parallel to the shaft 12 to near the motor-side axial end of the sliding ring 19, to bend from there by 90 ° to continue radially outward. At the end of the radial section of the spring holder 24 is then bent to the impeller 8 by 90 °, to finally move into a further radial portion in which radial projections 26 are formed.

The pump-side spring holder 25, however, has on its inner side a profiling for engagement in the spline profile in the region of the splined shaft section 22. The central recess 27 is profiled accordingly. The spring holder 25 extends from the recess 27 radially outward and is bent at its end by about 90 ° to the motor 1 out and end to the outside (see Fig. 3 ). The dimensioning of the spring holder 24, 25 is such that within the axially parallel outer portions of the spring holder 24 and 25, the spring 23 is guided laterally outwardly. The inwardly adjoining radial sections form the pressure surfaces for the spring 23. The spring holder 25 has in its axially parallel annular portion 28, three recesses 29 which are bent on one side to a support surface 30 and on the other side with a projection 31 are provided. These recesses 29 form in conjunction with the Projections 26 of the motor-side spring holder 24 positive locking means which ensure that during normal operation of the pump, in particular when the shaft 12 is driven in working direction 32, the rotational movement of the shaft 12 on the spring holder 25 and from there over the bearing surfaces 30 of the recesses 29 the radial end faces of the projections 26 and thus the spring holder 24 is transmitted, which surrounds the rotary slide ring 19 positively and this rotates with the shaft 12. By the support surfaces 30, which are formed by bending over a portion of the ring section material 28, the contact surface is enlarged relative to the projections 26, so that the projections 26 can not impress in the ring sections 28.

The projections 26 in conjunction with the recesses 29 form a bayonet connection. Thus, the spring holder 24 and 25 are moved for assembly purposes after placement on the shaft 12 under bias of the spring 23 toward each other until the projections 26 engage in the recesses 29 and then rotated counter to the direction of rotation 32, so that the projections 26 behind the projections 31st engage behind the bayonet and hold the spring 23 in a prestressed state. This serving only the mounting position can be reversed by turning the shaft in the direction 32, as is done automatically even after installation during operation when the engine anfährt in the direction 32.

Between the spring holders 24 and 25, however, not only the spring 23 is incorporated, but also a stop ring 33, which is arranged in the transition region between the cylinder portion 21 and the spline portion 22. The stop ring 33 is profiled on its inside so that it sits positively in the transition region 34 both in the axial direction towards the engine 1 and in the direction of rotation. For this purpose, the stop ring on its inside inclined surfaces 35 which cooperate with corresponding inclined surfaces in the transition region, to support the ring as viewed in the axial direction of the shaft towards the engine. The positive connection in the direction of rotation is effected by projections 36 which engage in the expiring spline profile in this area. The stop ring 33 supports the arranged on the pump shaft 12 in the spline shaft 22 impellers 8, which are clamped in the assembled state by means of an end nut relative to the stop ring 33.

The stop ring 33 is seated within the spring holder 25 and forms the inner guide for the spring 23 surrounding it. By this arrangement in conjunction with the stationary ring 19 cross-spring holder 24, the axial length of the centrifugal pump can be significantly reduced in this area compared to known designs, whereby the unit can be much more compact and due to the material savings also lighter in weight than known pumps ,

The mechanical seal 13 is mounted from the impeller side of the shaft 12. After the motor shaft 11 and pump shaft 12 are fixedly connected together and the connecting flange 5 is mounted, the mechanical seal 13 is mounted by first placing the stationary seal ring 14 with the O-ring 15 thereon from the impeller side onto the shaft and into the lining of the connecting flange 5 is set. Then, the rotary seal ring 19 is mounted with the O-ring 20 and the cross-spring holder 24 from the impeller-side end of the shaft 12, after which the stop ring 33 is placed, the spring 23 inserted and finally the spring holder 25 is placed. This is pressed under tension of the spring 23 on the spring holder 24 until the projections 26 engage in the recesses 29, after which the spring holders 24 and 25 are rotated counter to the direction of rotation 32 and held by the projections 31 in this prestressed state. Then the assembly takes place the impellers and the other pump components. The bayonet connection, which keeps the spring 23 under tension, can be released either by commissioning the pump when the shaft 11, 12 rotates in the direction 32 or possibly also manually. Then, the spring holder 25 is supported by the clamped wheels 8, so that now the spring force on the spring holder 24 and incorporated therein rotating sliding ring 19 presses and thus pushes the sliding surfaces 17 and 18 as intended to each other.

LIST OF REFERENCE NUMBERS

1 -

engine

2 -

rotary pump

3 -

pump housing

4 -

support flange

5 -

connecting flange

6 -

coat

7 -

suction

8th -

impellers

9 -

pressure port

10 -

camp

11 -

motor shaft

12 -

pump shaft

13 -

Mechanical seal

14 -

stationary sliding ring

15 -

O-ring of 14

16 -

Approaches of 14

17 -

Axial area of 14

18 -

Axial surface of 19

19 -

rotating seal ring

20 -

O-ring of 19

21 -

Cylinder section of 12

22 -

Spline shaft section of 12

23 -

Helical compression spring

24 -

motor-side spring holder

25 -

Impeller-side spring holder

26 -

Projections of 24

27 -

Recess of 25

28 -

ring section

29 -

Recesses in the ring section

30 -

bearing surface

31 -

head Start

32 -

Working direction of rotation

33 -

stop ring

34 -

Transitional area between 21 and 22

35 -

inclined surfaces

36 -

projections

Claims (14)

Multi-stage centrifugal pump having a pump housing (3) and a shaft (12) rotatably mounted therein, which has at least one cylindrical portion (21) at its motor end and then a splined shaft portion (22) on which rotors (8) are arranged, clamped between a stop ring (33) seated on the shaft (12) and the free shaft end, and with a mechanical seal (13) interposed between the cylindrical shaft portion (21) and the pump housing (3), the mechanical seal (13 ) arranged in the pump housing (3) and in contrast sealed stationary seal ring (14) and one on the shaft (12) arranged and sealed in contrast rotating seal ring (19) which mutually sliding and each spring-loaded Axialdichtflächen (17, 18), with between two spring holders (24, 25) arranged compression spring means (23), characterized in that the Ans Chlagring (33) in the transition region (34) of the shaft (12) between the cylindrical portion (21) and the spline shaft portion (22) and between the spring holders (24, 25) is arranged, wherein form-fitting means (26, 30) between the spring holders ( 24, 25) are provided, which are effective at least in the working direction of rotation (32) of the shaft (12). Centrifugal pump according to claim 1, characterized in that the stop ring (33) is held in a form-fitting manner on the shaft (12) at least in the axial direction towards the motor-side shaft end. Centrifugal pump according to one of the preceding claims, characterized in that the cylindrical shaft section (21) has a larger diameter than the spline portion (22) in the groove bottom and the diameter is preferably equal to or greater than the diameter of the spline portion (22) in the remaining area. Centrifugal pump according to one of the preceding claims, characterized in that the stop ring (33) is formed on its inside for positive engagement in the spline profile of the splined shaft portion (22). Centrifugal pump according to one of the preceding claims, characterized in that the stop ring (33) on its inside inclined surfaces (35), which at the at least one corresponding inclined surface of the shaft (12) in the transition region (34) of the shaft (12) between the support cylindrical portion (21) and the spline shaft portion (22). Centrifugal pump according to one of the preceding claims, characterized in that the spring means (23) at least partially overlap the stop ring (33) and the rotating slide ring (19). Centrifugal pump according to one of the preceding claims, characterized in that the spring means are formed by a helical compression spring (23). Centrifugal pump according to one of the preceding claims, characterized in that the spring holder (24, 25) positive locking means (26, 31), with which they are axially fixed to each other under bias of the spring means (23) for the purpose of assembly at least in one direction. Centrifugal pump according to one of the preceding claims, characterized in that the spring holders (24, 25) are mutually bayonetable, preferably such that the locking takes place counter to the working direction of rotation (32). Centrifugal pump according to one of the preceding claims, characterized in that the slide ring-side spring holder (24) is formed cranked, such that the spring means (23), in particular the helical compression spring surrounds the rotating slide ring (19). Centrifugal pump according to one of the preceding claims, characterized in that the impeller-side spring holder (25) has at least one positively engaging in the spline driver, which rotatably connects the spring holder (25) with the shaft (12). Centrifugal pump according to one of the preceding claims, characterized in that the stationary slide ring (14) preferably on its outer circumference positive locking means (16), with which this is secured in the pump housing (3) against rotation. Centrifugal pump according to one of the preceding claims, characterized in that the impeller-side spring holder (25) is pot-shaped and the sliding ring-side spring holder (24) open recesses (29) in the peripheral wall (28), in the radial projections (26) of the slide ring side Engage the spring holder (24). Centrifugal pump according to one of the preceding claims, characterized in that the edges of the recesses (29) in the engagement region of the projections (26) are formed reinforced, in particular by an enlargement of the bearing surfaces (30).

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