Centrifugal Pump Having Wear-Resistant Wear Plate With Scraper Element

Abstract

A centrifugal pump is configured to convey media containing solids. The centrifugal pump includes an open impeller. The open impeller has at least one blade and a mating element interacting therewith. The mating element includes an element which protrudes into a suction eye of the centrifugal pump and interacts with a leading edge of the at least one blade of the open impeller. The mating element is configured in two parts, a first part and a second part. The two parts are configured to render the element elastic.

Claims

1.-13. (canceled)

14. A centrifugal pump configured to convey media containing solids, the centrifugal pump comprising: an open impeller having at least one blade and a mating element interacting therewith, wherein the mating element comprises an element which protrudes into a suction eye of the centrifugal pump and interacts with a leading edge of the at least one blade of the open impeller, and the mating element is configured in two parts, a first part and a second part, the two parts being configured to render the element elastic.

15. The centrifugal pump as claimed in claim 14, wherein the element is configured to be integral to the second part of the mating element.

16. The centrifugal pump as claimed in claim 15, wherein the first part of the mating element has a greater hardness than the second part, and the hardness of the first part according to Brinell is more than 550 HB.

17. The centrifugal pump as claimed in claim 15, wherein the first part of the mating element has a greater hardness than the second part, and the hardness of the first part according to Brinell is more than 600 HB.

18. The centrifugal pump as claimed in claim 15, wherein the first part of the mating element has a greater hardness than the second part, and the hardness of the first part according to Brinell is more than 650 HB.

19. The centrifugal pump as claimed in claim 16, wherein the second part of the mating element is designed to be more ductile than the first part, and the elongation at break of the second part is more than 14.

20. The centrifugal pump as claimed in claim 19, wherein a tensile strength of the second part is more than 400 N/mm.sup.2.

21. The centrifugal pump as claimed in claim 20, wherein the first part and the second part of the mating element are connected to one another in a form-fitting and/or force-fitting manner.

22. The centrifugal pump as claimed in claim 21, wherein the mating element has a groove, and the groove extends from the first part to the second part and has an offset between the first and second parts.

23. The centrifugal pump as claimed in claim 20, wherein the mating element comprises at least one tension and/or compression screw configured to align the mating element.

24. The centrifugal pump as claimed in claim 23, wherein the first and second parts of the mating element are configured to be annular and/or trumpet funnel-like.

25. The centrifugal pump as claimed in claim 22, wherein the element has a shape of a trihedral pyramid with curved lateral faces, and extends in a direction of a rotation axis of the impeller.

26. The centrifugal pump as claimed in claim 25, wherein the mating element is formed from a metallic material, including a cast material or a non-corroding steel material.

27. The centrifugal pump as claimed in claim 25, wherein the mating element is formed by additive manufacturing.

28. The centrifugal pump as claimed in claim 27, wherein the mating element is designed as a wear plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the drawings:

[0043] FIG. 1 shows a perspective view of the centrifugal pump according to the disclosure, with an opened pump housing;

[0044] FIG. 2 shows a vertical section through the centrifugal pump;

[0045] FIG. 3 shows a section through the open impeller and the corresponding mating element;

[0046] FIG. 4 shows a perspective illustration of the mating element; and

[0047] FIG. 5 shows a further perspective illustration of the mating element.

DETAILED DESCRIPTION

[0048] FIG. 1 shows an exploded illustration of the centrifugal pump 1 according to the disclosure. The latter comprises a spiral housing 10, a suction-side mating element 2 in the form of a wear plate, and an impeller 20 rotating about a rotation axis A. The impeller 20 comprises two blades 20a which are curved rearward and by which the conveyed medium is suctioned by way of a cylindrical inlet opening 15 of the mating element 2, conveyed to the outlet side 13 by way of the conveying chamber 16 of the spiral housing 10, and is delivered by way of said outlet side 13. In other embodiments, the impeller 20 may also comprise fewer or more than two blades 20a. The blade or the blades 20a, respectively, have in each case one leading edge 20b which faces the mating element 2 and thus the fluid flow, as is shown in FIG. 3.

[0049] The wastewater to be conveyed can be mixed with a multiplicity of different solids, for example fibrous materials which can establish themselves on certain parts of the pump during the operation of the pump. For this reason, an element 5 which is integrally molded on the cylindrical inner wall of the mating element 2 and extends in the direction of the rotation axis A is provided.

[0050] The element 5 scrapes away solids which are contained in the conveyed medium and adhere to the impeller 20, in particular to the leading edges 20b of the blades 20a. The solids which have been scraped away can be supplied to the outlet side by way of a spiral groove 6 within the mating element 2, which is specially provided for this purpose.

[0051] In order to design the scraping effect of the element 5 in an optimal manner, the shape and position of said element 5 within the mating element 2 has to be adapted to the specific construction of the impeller and the housing. The length of the element 2 should be at least 30%, preferably at least 50%, or at best approximately 70% to 80%, of the radius of the cylindrical mating element 2.

[0052] FIG. 2 shows a vertical section through a centrifugal pump 1 which is installed horizontally. The relative position of the element 5 in relation to the spur 17 of the spiral housing 10 can influence the delivery of the scraped-off solids to the outlet side 13. The element 5 is favorably disposed so as to be offset from the spur 17 by the angle . The element 5, when viewed in the flow direction, is disposed in front of the spur 17. Solids such as rocks can potentially accumulate in the lower part of the spiral housing 10, or of the impeller 20, respectively. By disposing the element 5 in the environment of the spur 17, said element 5 is positioned outside accumulations of rocks. The angle is preferably between 0 and 45; the angle in the variant of embodiment illustrated is 25.

[0053] FIG. 3 shows a section through the open impeller 20 and the mating element 2 which interacts with the leading edge 20b of the at least one blade 20a of the impeller 20. In order for the flow in the pump inlet toward the impeller 20 to be influenced as little as possible by the element 5, the element 5 is shaped in the manner of a pyramid with a total of three, partially rounded lateral faces, and the base area almost bearing on the blade edge 20b of the impeller 20.

[0054] The spacing 31 between the blade edge 20b of the impeller 20 and the face of the scraping edge of the element 5 should be in a range between 0.05 mm and 3 mm, whereby this spacing can vary in the radial direction. An excessively large spacing has the risk that small solids cannot be caught by the element 5, whereas an excessively small spacing increases the risk of a collision between the element 5 and the impeller 20.

[0055] According to the disclosure, the mating element 2 is embodied in two parts, having a first part 3 and a second part 4. In the variant of embodiment illustrated, the element 5 is designed to be integral to the second part 4. Integral means that this is a component made of one material, the second part 4 and the element 5 thus have the same properties.

[0056] In this variant of embodiment of the disclosure, the hardness of the first part 3 according to Brinell is more than 550 HB. For the avoidance of damage by shock-like loads, the second part 4 of the mating element 2 with the element 5 is designed to be more ductile than the first part 3 of the mating element 2. The elongation at break as a measure of the ductility of the second part 4 and of the element 5 here is 18%. The tensile strength of the second part 4 for the elastic design of the element 5 is 400 N/mm.sup.2, and the notch impact strength is 14 N/cm.sup.2. As a result of the advantageous design embodiment of the second part 4 of the mating element 2, the latter is effectively protected against destruction by shock-like loads.

[0057] In the variant of embodiment of the disclosure illustrated, the second part 4 of the mating element 2 with the integrally formed element 5 has been formed from the material EN-GJS-400-18-LT by means of a casting process, whereby the first part 1 of the mating element 2 has been cast from the material EN-GJN-HB555 (XCr14).

[0058] Both parts 3, 4 of the mating element 2 form a unit as a complete functional component. For this purpose, the parts 3, 4 are connected to one another in a form-fitting as well as force-fitting manner, and joined to one another by means of an interference fit 30. The second part 4 of the mating element 2 here substantially forms the suction eye of the centrifugal pump 1.

[0059] The advantageous design embodiment of the mating element 2 in two parts 3, 4 with different properties achieves a wear plate which is designed to be particularly hard in terms of abrasive wear, and simultaneously a scraper element which is embodied to be particularly elastic and simultaneously shock-resistant in terms of shock-like loads.

[0060] FIG. 4 shows a perspective illustration of the mating element 2 which is fixed so as to form a component from the first part 3 and the second part 4 by means of six screws 32 that are mutually disposed at an angle of in each case 60. The element 5 protrudes into the inlet opening 15 and has a sharp edge 34 for fragmenting fibrous solids. The mating element 2, in particular the first part 3, has four bores 33 and is fastened to or in the pump housing by means of the bores 33, and adjusted in such a manner that a precise gap is formed between the impeller 20 and the mating element 2. The gap herein is 0.3 mm. It can furthermore be seen that the second element 4, when viewed in the flow direction, is disposed in front of the first element 3.

[0061] FIG. 5 shows a further, perspective illustration of the mating element 2. For the effective avoidance of permanent entanglements, the mating element 2 has a groove 6, whereby the groove 6 extends tangentially in an encircling manner from the first part 3 to the second part 4 of the mating element 2 and has an offset 7 between the parts 3, 4. The groove 6 comprises a permanently sharp cutting edge 35, whereby the offset 7 between the parts 3, 4 of the mating element 2 forms an additional cutting edge. Moreover, the element 5 in the second part 4 is disposed directly on the groove 6 so that the scraped-off solids can be discharged by way of the groove 6.

[0062] The foregoing disclosure has been set forth merely to illustrate the disclosure and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the disclosure may occur to persons skilled in the art, the disclosure should be construed to include everything within the scope of the appended claims and equivalents thereof.