PULLEY

Description

[0001] 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 plate, wherein the thickness of a wall of the blade changes over its extent and wherein a channel is formed between the blade and the cover plates.

[0002] Single-blade impellers of this type are typically used when conveying liquids containing solids. This is particularly true for wastewater with coarse-grained and long-fiber components. The distinguishing feature of these single-blade impellers is that, unlike other impeller types, they have only one blade over which the liquid is conveyed. This blade is designed to form a channel through which the liquid flows from a suction inlet. These single-blade impellers can be designed to be very robust and wear-resistant, enabling reliable and low-maintenance operation, especially when conveying liquids containing solids.

[0003] A problem in this context, however, is that the single channel or blade does not result in a uniform distribution of mass in the circumferential direction. This is due, on the one hand, to the asymmetrical shape and, on the other hand, to the hydraulic force that occurs when conveying the fluid and rotates with the impeller. The resulting uneven load becomes more problematic the larger the impeller's mass is. For this reason, there is always an effort to use the lightest possible impellers that still exhibit sufficiently high stability and wear resistance, although these two requirements are somewhat contradictory.

[0004] In this context, DE 44 28 702 A1 discloses a single-blade impeller in which the blade is not solid but rather formed with individual hollow chambers. The pressure and suction sides of the blade are connected by several webs, thereby separating the hollow chambers. The hollow chambers reduce the weight of the single-blade impeller and consequently its imbalance. However, the impeller is to be made of a metallic material, making its manufacture with hollow chambers comparatively complex.

[0005] DE 36 15 686 A1 therefore proposes to provide only a sheet metal base body into which a plastic insert body is placed. The flow-guiding components, in particular the suction side of the blade, are formed by the insert body. The use of plastic reduces the weight and thus also the imbalance.

[0006] From 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.

[0007] EP 3 480 473 A1 and US 2,120,277 A disclose multi-bladed pump impellers made of plastic, wherein the support discs, cover discs and impeller blades each have an internal supporting core.

[0008] Both the single-blade impellers and the multi-blade impellers have generally proven their worth. However, they still have room for improvement.

[0009] For this reason, the invention is based on the objective of providing a single-blade impeller that, compared to previously known single-blade impellers, is characterized by a high degree of stability and reduced imbalance.

[0010] This problem is solved by a single-blade impeller according to claim 1. Accordingly, a support body is arranged at least partially within the impeller body, which has a higher density than the impeller body itself. The support body is formed from a solid material. This support body provides the single-blade impeller with its essential stability, allowing a comparatively lightweight material to be used for the impeller body. This design not only minimizes imbalance but also positively influences vibration behavior. This results in an increased service life for the pump and drive bearings, as well as reduced stress on the impeller sealing gap, thereby significantly increasing efficiency and operational reliability. Likewise, the vibration behavior of the system in which the pump is installed, and also the noise generation, are reduced.

[0011] In a preferred embodiment of the invention, the density ratio between the impeller body and the support body is at least 1:2, preferably at least 1:3, and particularly preferably at least 1:4. The density of the impeller body can be in the range of 2 to 3 g / cm³, preferably between 2.2 and 2.8 g / cm³. In contrast, the density of the support body is in the range of 4 to 10 g / cm³, preferably between 6 and 9 g / cm³, and particularly preferably between 7 and 8 g / cm³.

[0012] A ferrous alloy is preferably used as the material for the support body. The support body can be shaped using a casting process, but also by a forming or machining process and / or a joining process. The impeller body is preferably made of a polymer or an epoxy resin and may also contain a proportion of a ceramic powder, e.g., silicon carbide. This ceramic powder typically has a particle size between 0.1 and 1 mm and gives the impeller body increased resistance to abrasive wear. The single-blade impeller itself can be manufactured by casting the impeller material around the support body. Alternatively, injection molding or an additive manufacturing process, e.g., 3D printing, is also suitable.

[0013] 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 imbalance, the base plate has a thickening over a circular segment-shaped 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 to extend into the wall of the blade, with the base plate being arranged at least partially in the second pressure-side cover plate near the drive. Preferably, the drivers extend over at least 60%, preferably over at least 70%, of the blade's vertical height, the vertical direction being parallel to the axis of rotation of the impeller.

[0014] This design ensures the strongest possible connection between the support body and the impeller body. Simultaneously, the support body can be shaped and aligned with the impeller body to further minimize or even completely eliminate imbalance. For example, the drive lugs can be positioned within the blade wall so that they extend into an area of ​​thin wall. The base plate can be symmetrical or asymmetrical, with an asymmetrical design being particularly suitable for compensating for imbalance.

[0015] Preferably, the support body and, in particular, the drive elements are designed such that the imbalance of the base body is compensated by at least 60%, preferably at least 75%, and most preferably at least 90%. Complete compensation or compensation of 100% is also possible.

[0016] The single-blade impeller is preferably designed as a radial impeller. This means that the conveyed medium exits the impeller essentially in a radial direction. The inflow generally occurs in the direction of the axis of rotation. For this reason, the first suction-side cover plate, furthest from the drive, preferably has an opening through which the conveyed medium can flow into the channel.

[0017] The invention also relates to the use of a single-vane impeller according to the invention in a centrifugal pump for pumping liquids containing solids according to claim 8 +& and a centrifugal pump according to claim 9 with a drive motor and a pump housing, wherein the single-vane impeller according to the invention is arranged inside the pump housing and is connected to a motor shaft of the drive motor via an impeller shaft.

[0018] Preferably, the single-blade impeller is connected to the impeller shaft via a keyway connection or a conical seat connection.

[0019] The invention will now be explained in more detail using an exemplary example. The figures show: 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 invention. Fig. 1 Fig. 3a,3 Biometric views of the impeller body and the support body. Fig. 4 The single-blade impeller in a cross-section perpendicular to the axis of rotation.

[0020] The Fig. 1 Figure 1 shows a pump arrangement comprising a pump 1 with a drive motor 2 and a single-impeller 3, wherein the single-impeller 3 is arranged within a pump housing 4. The single-impeller 3 is attached to a motor shaft 6 of the drive motor 2 via an impeller shaft 5 rotating about an axis of rotation A. In the illustration, the impeller shaft 5 and motor shaft 6 are formed as a single piece. Alternatively, the impeller shaft 5 and motor shaft 6 can be connected to each other via coupling elements.

[0021] The single-vane impeller 3 is attached to the impeller shaft 5 by a screw connection, and torque is transmitted via a key. Furthermore, the motor shaft 6 is supported by rolling bearings 7 and sealed against the single-vane impeller 3 by seals 8. In the illustrated embodiment, the pump assembly is mounted on a container 9, which forms the pump housing 4 in a section 10. However, the single-vane impeller 3 can also be used in conventional wet- or dry-mounted pump assemblies, which are arranged in a vertical or horizontal orientation. In these cases, the pump of the pump assembly has its own pump housing 4.

[0022] The impeller conveys a liquid containing solids through the pump housing 4. For this purpose, the impeller 3 has an opening at its end face through which the liquid flows in the direction of the axis of rotation A. The liquid exits the impeller 3 in a substantially radial direction through a line connected to the pump housing 4.

[0023] The exact design of the single-blade impeller is determined in particular by the Fig. 2 clearly. The single-blade impeller consists of an impeller body 11 and a support body 12. Both bodies are particularly evident in the Figuren 3a and 3bThe impeller body 11 is shown in an overall view. It has a blade 13 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 substantially perpendicularly from the base plate 16. The drivers 17 and 18 extend into the wall of the blade 13, with the base plate 16 being arranged at least partially within the pressure-side cover plate 15.

[0024] The support body 12 is manufactured 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 of a cast iron material and the impeller body 11 of a polymer, the polymer optionally containing a proportion of ceramic particles.

[0025] From the Fig. 3b It is further evident that the base plate 16 of the support body is asymmetrically designed. 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 along its length. To compensate for the imbalance, the base plate 16 has a thickening 19 over a circular segment-shaped section and a recess 20 on the opposite side. In the example shown, this recess 20 does not completely penetrate the base plate, although the invention also includes embodiments in which the recess is designed in the form of an opening. Furthermore, both the recess and the thickening extend as circular segments over the same circumference of the base plate 16.However, in this context, the thickness 19 and the recess 20 can differ in magnitude from each other in both the circumferential and rotational directions A. According to the invention, the base plate 16 has at least one thickness 19 and at least one recess 20.

[0026] The drive lugs 17 and 18 also contribute to compensating for the imbalance. Fig. 4 It can be deduced from this that these extend into areas of the blade 13 that have a comparatively thin wall. Thus, the mass in these areas is increased and brought into line with the other areas. The mass of the first drive element 17 can differ from the mass of the second drive element 18 if necessary.

Claims

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).