EP4034771B1 - Single-vane impeller - Google Patents

Description

The invention relates to a single-blade impeller for pumps, in particular centrifugal pumps with an impeller body, wherein a blade is arranged in the impeller body between a suction-side first and a pressure-side second cover disk, wherein the thickness of a wall of the blade changes over its extension and wherein a channel is formed between the blade and the cover disks.

Such single-blade impellers are usually used when liquids that contain solid impurities are to be pumped. In particular, this involves dirty water with coarse-grained and long-fiber components. The special feature of such single-blade impellers is that, in contrast to other types of impeller, only one blade is provided through which the liquid is pumped. The blade is designed in such a way that it forms a channel through which the liquid can flow from a suction mouth. Such single-blade impellers can be designed to be very robust and wear-resistant, so that reliable and low-maintenance operation is possible, especially when pumping liquids with solid components.

The problem in this context is that the mass is not evenly distributed in the circumferential direction due to the single channel or the single blade. This is due on the one hand to the asymmetrical shape and on the other hand to the hydraulic force that occurs when the medium is conveyed and rotates with the single blade wheel. The resulting uneven The greater the mass of the single-blade impeller, the more problematic the load is. For this reason, the aim is always to use single-blade impellers that are as light as possible, but which still have sufficiently high stability and high wear resistance, although these two requirements are to a certain extent contradictory.

The DE 44 28 702 A1 teaches in this context a single-blade wheel in which the blade is not solid-walled, but is designed with individual hollow chambers, whereby the pressure and suction sides of the blade are connected to one another via several webs and thus separate the hollow chambers from one another. The hollow chambers can reduce the weight of the single-blade wheel and therefore also the imbalance of the single-blade wheel. However, the single-blade wheel is to be made of a metallic material, so that production with hollow chambers is comparatively complex.

The DE 36 15 686 A1 therefore proposes to provide only one base body made of sheet metal, into which a plastic insert body is inserted. The flow-guiding components, in particular the suction side of the blade, are formed by the insert body. By using plastic, the weight and thus also the imbalance can be reduced.

From the US 3,743,437 A An impeller for a pump is known which has a blade to which an elastic element is attached in the region of the leading edge, wherein the elastic element comprises a stiffening element.

The EP 3 480 473 A1 and the US 2,120,277 A disclose multi-blade impellers for pumps made of plastic, wherein the support disks, cover disks and impeller blades each have an inner supporting core.

Both the generic single-blade impellers and the multi-blade impellers have generally proven themselves. However, they still need improvement.

For this reason, the invention is based on the object of specifying a single-blade wheel which, compared to the previously known single-blade wheels, is characterized by a high degree of stability and a reduced imbalance.

This object is achieved by a single-blade impeller according to claim 1. Accordingly, a support body is arranged at least in sections in the impeller body, which has a higher density than the impeller body. The support body itself is made of a solid material. This support body gives the single-blade impeller its essential stability, so that a comparatively light material can be used for the impeller body itself. Such a design not only minimizes the imbalance, but also has a positive effect on the vibration behavior. This increases the service life of the bearings of the pump and the drive and reduces the stress on the impeller sealing gap, which significantly increases efficiency and operational reliability. The vibration behavior of the system in which the pump is used and also the noise development are also reduced.

In a preferred development of the invention, the ratio of the density between the impeller body and the support body is at least 1:2, preferably at least 1:3, particularly preferably at least 1:4. The density of the impeller body can be in the range between 2 and 3 g/cm ³ , preferably between 2.2 and 2.8 g/cm ³ . In contrast, the density of the support body is in the range between 4 and 10 g/cm ³ , preferably between 6 and 9 g/cm ³ , particularly preferably between 7 and 8 g/cm ³ .

A ferrous material is preferably considered as the material for the support body. The support body can be shaped using a casting process, but also using a forming or chip-removing process and/or a joining process. The impeller body is preferably made of a polymer or an epoxy resin and can also contain a proportion of a ceramic powder, e.g. silicon carbide. This ceramic powder usually has a particle size of between 0.1 and 1 mm and gives the impeller body increased resistance to abrasive wear. The single-blade impeller itself can be manufactured in such a way that the material of the impeller is cast around the support body. Alternatively, injection molding or an additive process, e.g. 3D printing, can be used.

According to the invention, the support body has a pressure-side base plate and at least one driver projecting from the base plate. To compensate for the imbalance, the base plate has a thickening over a circular segment-like section and a recess on the opposite side. The number of drivers can be two, three, four or more. The driver(s) are preferably designed such that they extend into the wall of the blade, with the base plate being arranged at least in sections in the second pressure-side cover disk close to the drive. The drivers preferably extend over at least 60%, preferably over at least 70% of a vertical height of the blade, with the vertical direction being arranged parallel to the axis of rotation of the single-blade wheel.

Such a design ensures that the connection between the support body and the impeller body is as strong as possible. At the same time, the support body can be designed in such a way that the shape and alignment with the impeller body further minimize the imbalance or even completely compensate for it. For example, the drivers can be arranged within the blade wall in such a way that they extend into an area with a thin wall. The base plate can be designed symmetrically or asymmetrically, with an asymmetrical design being particularly suitable for compensating for an imbalance.

Preferably, the support body and in particular the drivers are designed such that the imbalance of the base body is compensated by at least 60%, preferably at least 75%, particularly preferably at least 90%. Complete compensation or compensation by 100% is also possible.

The single-blade impeller is preferably designed as a radial impeller. This means that the conveying medium leaves the impeller essentially in a radial direction. The inflow is usually in the direction of the axis of rotation. For this reason the first cover plate on the suction side, remote from the drive, preferably has an opening through which the conveying medium can flow into the channel.

The invention also relates to the use of a single-blade impeller according to the invention in a centrifugal pump for conveying liquids interspersed with solid admixtures according to claim 8 +& as well as a centrifugal pump according to claim 9 with a drive motor and a pump housing, wherein the single-blade impeller according to the invention is arranged within the pump housing and is connected to a motor shaft of the drive motor via an impeller shaft.

Preferably, the single-blade impeller is connected to the impeller shaft via a keyway connection or a conical seat connection.

Fig. 1

eine Pumpanordnung mit einem erfindungsgemäßen Einschaufelrad im Querschnitt

Fig. 2

eine Detailansicht des Einschaufelrades im Pumpengehäuse gemäß der Fig. 1

Fig. 3a,3b

isometrische Ansichten des Laufradkörpers und des Stützkörpers

Fig. 4

das Einschaufelrad in einem Querschnitt senkrecht zur Rotationsachse

The invention is explained in more detail below using an exemplary example. Shown are:

Fig. 1

a pump arrangement with a single-blade impeller according to the invention in cross section

Fig. 2

a detailed view of the single-blade impeller in the pump housing according to the Fig. 1

Fig. 3a,3b

isometric views of the impeller body and the support body

Fig. 4

the single-blade wheel in a cross-section perpendicular to the axis of rotation

The Fig. 1 shows a pump arrangement with a pump 1 with a drive motor 2 and a single-blade impeller 3, wherein the single-blade impeller 3 is arranged within a pump housing 4. The single-blade impeller 3 is attached to a motor shaft 6 of the drive motor 2 via an impeller shaft 5 rotating about a rotation axis A. Impeller shaft 5 and motor shaft 6 are formed in one piece in the illustration shown. Alternatively, impeller shaft 5 and motor shaft 6 can be connected to one another via coupling elements.

A screw connection is provided to fasten the single-blade impeller 3 to the impeller shaft 5, and the torque is transmitted via a key. In addition, the motor shaft 6 is mounted on roller bearings 7 and sealed with respect to the single-blade impeller 3 using seals 8. In the embodiment shown, the pump arrangement is arranged on a container 9, which forms the pump housing 4 in an area 10. The single-blade impeller 3 can, however, also be used in the usual wet or dry pump arrangements that are arranged in a vertical or horizontal orientation. The pump of the pump arrangement has its own pump housing 4.

The single-blade impeller conveys a liquid interspersed with solid impurities through the pump housing 4. For this purpose, the single-blade impeller 3 has an opening on the front side through which the liquid flows in the direction of the axis of rotation A. The liquid leaves the single-blade impeller 3 in a substantially radial direction through a line connected to the pump housing 4.

The exact design of the impeller is determined in particular by the Fig. 2 The single-blade impeller consists of an impeller body 11 and a support body 12. Both bodies are particularly in the Figures 3a and 3b shown in an overall view. The impeller body 11 has a blade 13 which is arranged between a first, here lower suction-side cover plate 14 and a second, here upper pressure-side cover plate 15. The support body 12 has a base plate 16, with a first driver 17 and a second driver 18 extending essentially perpendicularly from the base plate 16. The drivers 17, 18 extend into the wall of the blade 13, with the base plate 16 being arranged at least in sections in the pressure-side cover plate 15.

The support body 12 is made in one piece from a material that has a higher density than the impeller body 11. The density ratio is at least 2:1. To achieve such a density ratio, the support body 12 is made from a cast iron material and the impeller body 11 is made from a polymer, the polymer having a proportion of ceramic particles if necessary.

From the Fig. 3b it is also evident that the base plate 16 of the support body is designed asymmetrically. This allows the imbalance of the impeller body 11 to be compensated to a certain extent. This imbalance is caused by the uneven mass distribution of the blade 13, which in particular has a wall thickness that varies over its extension. To compensate for the imbalance, the base plate 16 has a thickening 19 over a circular segment-like section and a recess 20 on the opposite side. In the example shown, this recess 20 does not completely penetrate the base plate, whereby the invention also includes designs in which the recess is designed in the form of an opening. In addition Furthermore, both the recess and the thickening extend as a circular segment over a circumference of the base plate 16 that is equal in amount. However, in this context, the thickening 19 and the recess 20 can differ in amount from one another both in the circumferential direction and in the rotational direction A. According to the invention, it is provided that the base plate 16 has at least one thickening 19 and at least one recess 20.

The drivers 17,18 also contribute to compensating the imbalance. Fig. 4 In this regard, it can be seen that these extend into areas of the blade 13 that have a comparatively small wall thickness. The mass in these areas is thus increased and adjusted to the other areas. The mass of the first driver 17 can deviate from the mass of the second driver 18 if necessary.

Claims (9)

1. Single-vane impeller (3) for pumps for delivering liquids permeated with solid additions, with an impeller body (11), a vane (13) being arranged in the impeller body (11) between a first cover disc (14) and a second cover disc (15), the thickness of a wall of the vane (13) changing over its extent, and a channel being formed between the vane (13) and the cover discs (14, 15), at least portions of a supporting body (12) being arranged in the impeller body (11), which supporting body (12) has an increased density in comparison with the impeller body (11), characterized in that the supporting body (12) has a base plate (16) and at least one driver (17, 18) which projects from the base plate (16), and the base plate (16) has, in order to balance the unbalance, a thickened portion (19) over a circular segment-like portion and a cut-out (20) on the opposite side.
2. Single-vane impeller (3) according to Claim 1, characterized in that the ratio of the density between the impeller body (11) and the supporting body (12) is at least 1:2, preferably 1:3.
3. Single-vane impeller (3) according to Claim 1 or 2, characterized in that the impeller body (11) has a density between 2 and 3 g/cm³, preferably between 2.2 and 2.8 g/cm³.
4. Single-vane impeller (3) according to one of Claims 1 to 3, characterized in that the supporting body (12) has a density between 6 and 9 g/cm³, preferably between 7 and 8 g/cm³.
5. Single-vane impeller (3) according to Claim 4, characterized in that at least portions of the base plate (16) are arranged in the second cover disc (15), and the at least one driver (17, 18) extends into the wall of the vane (13).
6. Single-vane impeller (3) according to one of Claims 1 to 5, characterized in that the supporting body (12) is configured in such a way that it balances at least 60% of the unbalance of the impeller body (11).
7. Single-vane impeller (3) according to Claim 5 or 6, characterized in that the at least one driver (17, 18) extends over at least 60%, preferably over at least 70% of a height, running in the vertical direction, of the vane (13).
8. Use of a single-vane impeller (3) according to one of Claims 1 to 7 in a pump, in particular centrifugal pump, for delivering liquids permeated with solid additions.
9. Centrifugal pump with a drive motor (1) and a pump housing (4), a single-vane impeller (3) according to one of Claims 1 to 7 being arranged within the pump housing (4) and being connected via an impeller shaft (5) to a motor shaft (6) of the drive motor (1).

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