Vortex pump

Abstract

Vortex pump with an impeller (2). Said impeller (2) comprises blades (7) for delivering solids-containing media. The blades (7) are arranged in bundles (12). The distance (14) of the blades (7) in said bundles (12) is smaller than the distance (13) of the bundles (12) from each other.

Description

Description Free current pump The invention relates to a free-flow pump with an impeller that has blades for conveying media containing solids. These free-flow pumps are also known as vortex pumps, whose pumping capacity is transferred to the fluid by a rotating, bladed disc, the so-called free-flow impeller. Free-flow impellers are particularly suitable for pumping media containing solids, such as wastewater. The free-flow impeller is a radial impeller that has a large opening for the solids contained in the pumped medium and is not very susceptible to malfunctions. WO 2004 / 065796 A1 describes a free-flow pump for pumping liquids containing solids. A gap exists between the impeller and the suction-side casing wall to allow solids to pass through the pump without clogging. The transition from the suction-side casing wall to the wall of the housing chamber located radially to the impeller is stepless. The housing chamber is asymmetrically designed. EP 1 616 100 B1 describes a free-flow pump whose impeller consists of a support disc fitted with open blades. The blades have different heights. A suction-side casing wall is conical. The distance between the casing wall and the leading edges of the taller blades of the impeller decreases with diameter. A passage with a minimum extension follows the leading edge of a lower-height blade inclined towards the impeller exit. The term "ball passage" refers to a free, unconstricted passage through the impeller. It describes the largest permissible diameter of solids to ensure unblocked passage. It is specified as a ball diameter in millimeters. The ball passage corresponds to a maximum of the nominal diameter of the suction or discharge port. To achieve this maximum possible ball passage in conventional free-flow pumps, the distance between the impeller's free-flowing front and the suction-side housing wall must also be at least equal to the nominal diameter of the suction or discharge port. If the uncapped space between the impeller's front and the opposite housing wall exceeds a certain size, the efficiency of the free-flow pump decreases. The greater the distance between the impeller and the suction-side wall, the lower the efficiency. The thicker the housing wall, the lower the efficiency of the free-flow pump. The object of the invention is to provide a free-flow pump that can pump media containing larger solids and achieves the highest possible efficiency by design. The free-flow pump should be characterized by the most cost-effective manufacturing method and ensure a long service life. Furthermore, the free-flow pump should be as versatile as possible, have low susceptibility to failure, and exhibit a favorable NPSH value. Cavitation damage should be avoided. This problem is solved by a free-flow pump with the features of claim 1. Preferred embodiments can be found in the dependent claims, the description, and the drawings. According to the invention, the blades on the free-flow impeller are arranged in bundles. The distance between the blades within the bundles is smaller than the distance between the bundles themselves. This design ensures sufficient sphere passage while maintaining a high pumping efficiency. The bundled arrangement of the blades on the support disc allows for a reduction in the distance between the inlet-side housing wall and the blade front while still ensuring sufficient ball passage. Since the distances between the bundles are greater than the distances between the blades within the bundles, a sufficiently large ball passage is guaranteed even if the distance between the blade fronts of the impeller is smaller than the inner diameter of the suction or discharge port. This prevents blockages and simultaneously achieves high conveying efficiency. The bundled arrangement of the blades allows for a reduction in the distance between the impeller and the suction-side... Reducing the housing wall thickness without causing blockages increases the efficiency of the free-flow pump. Preferably, the distance of the blade front of the impeller is less than 90%, in particular less than 80%, of the diameter of the suction opening or the inner diameter of the suction nozzle. Each bundle comprises at least two shovels. Bundles with two or three shovels each prove to be particularly advantageous. In one embodiment of the invention, each bundle comprises four shovels. The support disc of the free-flow impeller has a hub projection on the suction side, to which the blades engage. The blades project from the support disc in the suction direction and have a curvature opposite to the direction of rotation. All blades can have the same curvature. In an alternative configuration, the blades have different curvatures. For example, blades with different curvatures can be arranged within a single bundle. Advantageously, the spacing of the blades within the bundles is less than 90%, preferably less than 80%, and particularly less than 70%, of the spacing between the bundles. In a particularly advantageous embodiment of the invention, the free-flow impeller comprises two bundles of blades, which are preferably arranged offset from each other by 180°. It is advantageous if each bundle comprises the same number of blades. The spacing of the blades within the bundles and / or the spacing of the bundles to each other are preferably specified as blade pitch angles. According to the invention, the blade pitch angles within the bundles are smaller than the blade pitch angles between the bundles. Advantageously, the blade pitch angles between the bundles are greater than 60°, preferably greater than 70°, and particularly greater than 80°. It is advantageous if the blade pitch angles within the bundles are less than 70°, preferably less than 60°, and particularly less than 50°. In a particularly advantageous embodiment of the invention, the impeller and blades are formed in one piece. It is advantageous if the impeller and / or the blades are made of a metallic material. Preferably, a cast material is used. In one variant of the invention, the angles of the blade pitch between the bundles are not an integer multiple of the angles of the blade pitch within the bundles, so that the bundle-wise arrangement cannot be attributed to an impeller with blades of the same angle pitch in which individual blades are omitted. In a particularly advantageous embodiment of the invention, the height of the blades decreases in the radial direction relative to a reference plane. This decrease preferably occurs with a bevel angle of more than 2°, and in particular more than 3°. It proves advantageous if the reduction in the height of the blades is carried out with a bevel angle of less than 8°, in particular less than 7°. Further features and advantages of the invention will become apparent from the description of exemplary embodiments with reference to drawings and from the drawings themselves. This shows: Figure 1 shows a schematic meridian section through a free-flow pump, Figure 2 shows a perspective view of a free-flow wheel with two bundles, each having two blades. Figure 3 shows a top view of the free-flow wheel as depicted in Figure 2. Figure 4 shows a perspective view of a free-flow wheel with two bundles, each having three blades. Figure 5 shows a top view of the free-flow wheel as depicted in Figure 4. Figure 6 shows an arrangement of a free-flow impeller in a pump housing, Figure 7 is a top view of a free-flow turbine with a section line AA, Figure 8 is a sectional view along the line AA of the turbine shown in Figure 7. Free-flow bicycle. Figure 1 shows a free-flow pump in whose housing 1 an impeller 2 is positioned. The impeller 2 is non-rotatably connected to a shaft, which is not shown in Figure 1. A hub body 4, which has a bore 5 for screwing in a bolt, serves to mount the impeller 2. The impeller 2 is designed as a free-flow impeller. Several blades 7 are arranged on a support disc 6 of the impeller 2. A blade-free space 9 is formed between the impeller 2 and the inlet-side housing wall 8. The suction opening 10 is formed by a suction-side housing part 11. Suction opening 10 forms an inlet for the solids-containing medium and has a diameter D. The suction-side housing part 11 is designed as a suction cover. The impeller 2 is arranged in a pump housing 15. The front face of the free-flow impeller 2 has a distance A at its outer edge to the inside of the suction-side housing part 11. The distance A is preferably defined as the distance that a normal perpendicular to the suction-side housing part 11 extends. The housing wall 8 is positioned towards the outer edge of the blade front of the impeller 2. The distance A is smaller than the diameter D. The height h of the blades 7 decreases in the radial direction, so that the blade front has a slightly sloping or conical shape. Figure 2 shows a perspective view of the impeller 2, which is designed as a free-flow impeller. The impeller 2 is an open radial impeller that does not have a cover plate. On the support disc 6, two bundles 12 of blades 7 are arranged. Each bundle 12 comprises two blades 7. The two bundles 12 are arranged offset by 180° from each other on the hub body 4 of the impeller 2. Figure 3 shows a top view of the impeller 2 as depicted in Figure 2. The distance 13 between the bundles has a blade pitch angle of 20°. The distance 14 between the blades 7 within the bundles 12 has a blade pitch angle of 60°. Thus, the blade pitch angles between the bundles 12 are twice as large as the blade pitch angles within the bundles. The angles of the bucket division between the bundles 12 are an integer multiple of the angles of the bucket division within the bundles 2. Figure 4 shows a perspective view of an impeller 2, in which two bundles 12 of blades 7 are arranged on a support disc 6, each bundle 12 comprising three blades 7. The two bundles are arranged offset from each other by 180° on the hub body 4 of the impeller 2. Figure 5 shows a top view of the impeller 2 as depicted in Figure 4. The distance 13 between the bundles 12 has a blade pitch angle of 84°. The distance 14 between the blades 7 within the bundles 12 has a blade pitch angle of 48°. Thus, the blade pitch angles between the bundles are 1.75 times larger than the blade pitch angles within the bundles 12. Therefore, the blade pitch angles between the bundles 12 are not integer multiples of the blade pitch angles within the bundles 12. Figure 6 shows a bend into the free-flow pump, in which an impeller 2 is located in the The pump housing is located in part 15. The housing is a spiral casing. The solids-containing medium leaves the free-flow pump through a pressure port 17. Figure 7 shows the impeller 2 as depicted in Figure 6 with a section line AA. Figure 8 shows a section along this line AA. The height h of the blades 7 decreases in the radial direction, i.e., towards the outer diameter of the impeller. This decrease is relative to a reference plane 16, which is partially shown as a dashed line in Figure 8. In the embodiment example, the decrease is achieved with a chamfer angle α of 5°. Figure 8 shows a sphere 18 in an upper and a lower position. The sphere 18 has a diameter d and a radius a. According to the lower position of the sphere 18, the sphere 18 plunges by a depth b into the spaces of the impeller 2 between the bundles 12. This plunging segment of the sphere has a secant c. By arranging the blades 7 in bundles 12 according to the invention, a sphere with a diameter d corresponding to the diameter of the suction inlet D can penetrate to a depth b into the spaces between the bundles 12. This allows the distance A of the blade front to the suction-side housing wall 1 to be reduced by this depth b compared to the diameter d, so that the free-flow pump has a higher efficiency while still ensuring the maximum sphere passage d of the diameter D of the suction inlet 10. The following relationship exists between the distance A, the depth b, and the diameter D: A + b = D (Formula 1). The depth b can be calculated as follows: (Formula 2).

Claims

1. A non-chokable pump comprising an impeller (2) which has blades (7) for delivering solids-containing media, characterized in that blades (7) are arranged in bundles (12), wherein the spacing (14) of the blades (7) within the bundles (12) is smaller than the spacing (13) of the bundles (12) to one another, wherein the spacing (14) of the blades (7) within the bundles (12) and the spacing of the bundles (12) to one another are specified as angles of the blade separation.

2. The non-chokable pump according to Claim 1, characterized in that each bundle (12) has at least two blades (7).

3. The non-chokable pump according to Claim 1, characterized in that each bundle (12) comprises at most four blades (7).

4. The non-chokable pump according to Claim 1, characterized in that the spacing (14) of the blades (7) in the bundles (12) is less than 90%, of the spacing of the bundles (12) to one another.

5. The non-chokable pump according to Claim 1, characterized in that the angles of the blade separation between the bundles (12) are more than 60°.

6. The non-chokable pump according to Claim 1, characterized in that the angles of the blade separation within the bundles (12) are less than 70° .

7. The non-chokable pump according to Claim 1, characterized in that the impeller (2) is formed integrally with the blades (7). 8.The  non-chokable pump according to Claim 1, characterized in that the impeller (2) or the blades (7) are produced from a metallic material.

9. The non-chokable pump according to Claim 1, characterized in that the spacing (A) of the blade, at the outer radius of the impeller (2), to the casing wall (11) is less than 90%  of the diameter (D). 10.The  non-chokable punp  according to Claim 1, characterized in that each bundle (12) comprises an equal number of blades (7). 11.The  non-chokable pump according to Claim 1, characterized in that the bundles (12) are arranged so as to be offset from one another by 180°.

12. The non-chokable pump according to Claim 1, characterized in that the angles of the blade separation between the bundles (12) are is larger than the angles of the blade separation within the bundles (12) by more than a factor of 1.2 .

13. The non-chokable pump according to Claim 1, characterized in that the angles of the blade separation between the bundles (12) are not an integer multiple of the angles of the blade separation within the bundles (12).

14. The non-chokable pump according to Claim 1, characterized in that the height (h) of the blades (7) decreases in the radial direction, with the decrease occurring at a bevel angle (α) of more than 2°.

15. The non-chokable pump according to Claim 1, characterized in that spaces for dipping a ball by a depth (b) are arranged between the bundles (12).

16. The non-chokable pump according to Claim 1, characterized in that all the blades (7) have the same curvature.

17. The non-chokable pump according to Claim 1, characterized in that the blades (7) within the bundles (12) have different curvatures.

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