Abstract
A centrifugal pump for conveying media containing solids includes at least one arrangement for reducing a backflow from a first chamber into a second chamber. The at least one arrangement includes at least one non-rotating element that cooperates with at least one rotating counter element. At least one of the at least one non-rotating element and the at least one rotating element I coated at least in parts by a tetrahedral hydrogen-free amorphous carbon layer.
Claims
1-14. (canceled)
15. A centrifugal pump for conveying solids-containing media, comprising: at least one arrangement configured to reduce backflow from a first space into a second space, the arrangement including at least one nonrotating element that cooperates with at least one rotating counterpart element to minimize backflow, wherein the at least one nonrotating element at least partly has a layer of carbon.
16. The centrifugal pump as claimed in claim 15, wherein the at least one nonrotating element is disposed directly on a housing part of the pump.
17. The centrifugal pump as claimed in claim 15, wherein the at least one nonrotating element is a split ring.
18. The centrifugal pump as claimed in claim 17, wherein the nonrotating element has a layer of carbon on an axial surface.
19. The centrifugal pump as claimed in claim 17, wherein the at least one nonrotating element has a layer of carbon on a radial surface.
20. The centrifugal pump as claimed in claim 19, wherein the at least one nonrotating element has a layer of carbon on an axial surface.
21. The centrifugal pump as claimed in claim 20, wherein the at least one nonrotating element cooperates with the at least one rotating counterpart element disposed on a cover plate of an impeller of the pump, or one or both of an axial surface and a radial surface of the cover plate.
22. The centrifugal pump as claimed in claim 21, wherein the at least one rotating counterpart element is a race.
23. The centrifugal pump as claimed in claim 22, wherein the at least one rotating counterpart element at least partly has a layer of carbon.
24. The centrifugal pump as claimed in claim 23, wherein the closed impeller at least partly has a layer of carbon on one or both of a cover plate axial surface and a cover plate radial surface.
25. The centrifugal pump as claimed in claim 15, wherein one or both of the at least one nonrotating element and the at least one rotating counterpart element is formed from a metallic material.
26. The centrifugal pump as claimed in claim 25, wherein the metallic material is a cast material or a stainless steel material.
27. The centrifugal pump as claimed in claim 20, wherein the carbon layer is an amorphous carbon layer.
28. The centrifugal pump as claimed in claim 20, wherein the carbon layer is a tetrahedral hydrogen-free amorphous carbon layer.
29. The centrifugal pump as claimed in claim 23, wherein the carbon layer is a tetrahedral hydrogen-free amorphous carbon layer.
30. The centrifugal pump as claimed in claim 24, wherein the carbon layer is a.
31. The centrifugal pump as claimed in claim 28, wherein the thickness of the carbon layer is more than 0.5 .Math.m and less than 18 .Math.m.
32. The centrifugal pump as claimed in claim 28, wherein the thickness of the carbon layer is more than 1.5 .Math.m and less than 14 .Math.m.
33. The centrifugal pump as claimed in any of claim 31, wherein the surface hardness of the carbon layer-coated surface of the at least one nonrotating element is more than 20 GPa and less than 120 GPa.
34. The centrifugal pump as claimed in any of claim 33, wherein the surface hardness of the carbon layer-coated surface of the at least one nonrotating element is more than 40 GPa and less than 100 GPa.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a section diagram of a centrifugal pump for conveying of solids-containing medium with a closed impeller in accordance with an embodiment of the present invention.
[0042] FIG. 2 is a section diagram of a centrifugal pump for conveying of solids-containing medium with a closed single-vane impeller in accordance with an embodiment of the present invention.
[0043] FIG. 3 is a section diagram of a centrifugal pump for conveying of solids-containing media with a closed single-vane impeller in accordance with an embodiment of the present invention.
[0044] FIG. 4 is a detail enlargement in the region of a suction mouth of the pump in accordance with an embodiment of the preent invention.
[0045] FIG. 5 is a detail section of a fixed, nonrotating element in accordance with an embodiment of the preent invention.
DETAILED DESCRIPTION
[0046] FIG. 1 shows a section diagram of a centrifugal pump for conveying of solids-containing media with two arrangements for reduction of backflow 13, 25 from a first space into a second space. The arrangements 13, 25 comprise two nonrotating elements 2, 6, which, in this working example, interact with the closed impeller 4. This working example is a spiral housing pump with a horizontal setup. The elements 2 and 6 in this working example are configured as split rings. The solids-containing medium enters the pump via the suction mouth 1, kinetic energy is imparted to it by the closed impeller 4, which is connected to the shaft 9 in a rotationally fixed manner by the mount 12, and it leaves the housing portion 10, in the form of a pump housing in this example, via the pressure port 5. The shaft 9 is mounted rotatably by means of the ball bearing 8. The housing portion 7, in the form of a pressure cap in this working example, closes the pump space in the drive direction. Ideally, elements 2 and 6 are coated with a carbon layer, preferably with an amorphous carbon layer, especially with ta-C. Thus, particularly ideal protection from abrasive wear, which inevitably acts on the split rings in the conveying of solids-containing media, is achieved. Owing to the smooth and extremely hard ta-C coating of the split rings, it is possible to dispense with a ceramic material basis such as silicon carbide. The split rings may be manufactured from a standard cast material or a customary stainless steel material, and are protected by the ta-C coating from the abrasive action of the solids-containing media.
[0047] In the region of the suction mouth 1, a fixed, nonrotating element 2, here in the form of a split ring, in the interior of the housing portion 10 is connected to the housing portion 10 by means of a press fit. The element 2 and the impeller 4 are spaced apart from one another, such that a gap is formed between the element 2 and the impeller 4, which functions as a sealing gap with geometrically identical faces.
[0048] FIG. 2 shows a section diagram of a centrifugal pump for conveying of solids-containing media, having a means of reducing backflow 13 from a first space into a second space. The arrangement 13 comprises a fixed, nonrotating element 2, which, in this working example, interacts with the closed single-vane impeller 4. The element 2 takes the form of a split ring in the example. The solids-containing medium enters the pump via the suction mouth 1, kinetic energy is imparted to it by the closed single-vane impeller 4 which is connected to the shaft 9 in a rotationally fixed manner, and it leaves the housing portion 10 via the pressure port 5. The shaft 9 is mounted rotatably by means of the ball bearings 8. The housing portion 7, in the form of a pressure cap in this working example, closes the pump space in the drive direction. According to the invention, the element 2 has been coated with a carbon layer, preferably with an amorphous carbon layer, especially with ta-C. Thus, particularly ideal protection from abrasive wear and also against the encroachment of the closed single-vane impeller toward the split ring is achieved.
[0049] FIG. 3 shows a section diagram of a centrifugal pump for conveying of solids-containing media, having arrangements for reduction of backflow 13 from a first space into a second space. The arrangement 13 comprises a fixed, nonrotating element 2, which, in this working example, interacts with the closed single-channel impeller 4. The element 2 in this working example takes the form of an L-shaped split ring, the surface of which is coated with ta-C. The solids-containing medium flows into the pump via the suction mouth 1, kinetic energy is imparted to it by the closed single-vane impeller 4 which is connected to the shaft 9 in a rotationally fixed manner, and it leaves the housing portion 10, in the form of a pump housing, via the pressure port 5. The shaft 9 is mounted rotatably by means of the ball bearings 8. The housing portion 7, in the form of a pressure cap in this execution, closes the pump space in the drive direction. According to the invention, the L-shaped element 2, also referred to as angular split ring, is coated with a carbon layer, preferably with an amorphous carbon layer, especially with ta-C. Thus, particularly ideal protection from abrasive wear and also against the encroachment of the closed single-vane impeller 4 toward the split ring is attained.
[0050] FIG. 4 shows a detail enlargement in the region of the suction mouth 1 in one variant of the invention. The centrifugal pump has an arrangement for reduction of backflow 13 in the form of a gap seal. This comprises a rotating component 14, in the form of a race, and a nonrotating component 2, in the form of a split ring. The rotating component 14 is disposed on a radial outer face of the cover plate 3 of the impeller 4. The rotating component 14 thus rotates with the impeller 4. The nonrotating component 2 is disposed on the housing portion 10 and has a radial inside of the ring as guide, which interacts with the radial outside of the ring of the rotating component 14, in the form of an angular race in the working example, and forms the gap seal. According to the invention, the element 2 and the rotating component 14 are coated with a carbon layer, preferably with an amorphous carbon layer, especially with ta-C. This achieves particularly ideal protection from abrasive wear.
[0051] In the execution according to the diagram in FIG. 4, in addition to an arrangement for reduction of backflow 13, a further arrangement 20 is provided, comprising a rotating element 22 and a nonrotating element 21. The rotating element 22 takes the form of a ring which is disposed at the axial end face of the cover plate 3 and is also referred to as angular race. For this purpose, the rotating element 22 has a projection 19 that extends in axial direction and engages with a groove 15 in the cover plate 3. The nonrotating element 21 takes the form of an axially movable ring which is guided by a face 16 of the housing portion 10 against a radial movement. A force-generating element 17 exerts a force on the nonrotating element 21 and pushes the nonrotating element 21 against the rotating element 22. The force-generating element 17 takes the form of a spring. In the working example, a corrugated spring is used. In an alternative execution of the invention, it is possible to use a sinusoidal spring or a group spring arrangement. The nonrotating element 21 is sealed by the sealing element 18 with respect to the housing portion 10. The sealing element 18 is preferably an O ring.
[0052] The rotating element 22 and the nonrotating element 21 in the working example are made from a stainless steel material, coated in accordance with the invention with ta-C. The two mutually axially aligned end faces of the rotating element 22 and of the nonrotating element 21 are pushed against one another by the force-generating element 17. The result is a minimal gap. Friction is minimized by the ta-C coating. A lubricant film of conveying medium is formed in the gap between the faces of the rotating element 22 and of the nonrotating element 21 that are in contact. The arrangement 20 together with the device 13 prevents backflow from a pressure space 5 of the pump into a suction space 1 of the centrifugal pump.
[0053] FIG. 5 shows a detail section of a nonrotating element 2, coated with a carbon layer at an axial surface 23 and a radial surface 24. The coating with ta-C at at least one split ring end face and at least one inner face of the split ring allows split rings to be manufactured from a standard cast material or a stainless steel material, and ta-C coating allows wear-resistant properties to be obtained.
[0054] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
