Centrifugal pump having an arrangement for sealing

Abstract

A sealing arrangement for a centrifugal pump is provided. The sealing arrangement permits a sealing gap between a rotating element such as a pump impeller and a non-rotating element such as a pump casing to be minimized, while protecting against element wear from gap reduction and element contact, particularly during transient operation such as pump start up. At least one of the rotating element and the non-rotating element is provided with a plurality of movably mounted bodies configured to rotate and maintain separate the rotating and non-rotating elements when the sealing gap is reduced. The elements and the bodies may be formed in an additive manufacturing process.

Claims

1. A sealing arrangement for a centrifugal pump, comprising: a rotating element of the pump; a non-rotating element of the pump, the non-rotating element being arranged in the pump with a sealing gap formed between the rotating element and the non-rotating element, and the sealing gap separating a higher pressure chamber of the pump from a lower pressure chamber of the pump in a direction parallel to a rotation axis of the rotating element; and a plurality of movably mounted bodies at a sealing gap side of one or both of the rotating element and the non-rotating element, the plurality of bodies having a generated surface for rolling, wherein the plurality of bodies are configured to prevent wear of one or both of the rotating and non-rotating elements by a rolling movement of the plurality of bodies when the sealing gap decreases in size radially due to relative motion between the rotating element and the non-rotating element, when contact occurs between the plurality of bodies and the one or both of the rotating and non-rotating elements, the contact is direct contact between the plurality of bodies and the one or both of the rotating and non-rotating elements, and in a rest state in which the rotating element is not rotating, a portion of the rotating element radially facing the plurality of bodies does not radially overlap the plurality of bodies.

2. The sealing arrangement as claimed in claim 1, wherein the plurality of bodies are embedded in a structure in a form-fitting manner.

3. The sealing arrangement as claimed in claim 2, wherein the plurality of bodies are balls.

4. The sealing arrangement as claimed in claim 2, wherein the plurality of bodies have a cylindrical section.

5. The sealing arrangement as claimed in claim 1, wherein the plurality of bodies are arranged on the non-rotating element, and the non-rotating element is a split ring.

6. The sealing arrangement as claimed in claim 1, wherein one or both of the rotating and non-rotating elements includes one or both of gap loss minimization honeycombs and gap loss minimization cells.

7. The sealing arrangement as claimed in claim 1, wherein the rotating and non-rotating elements and the plurality of bodies are formed from the same material.

8. The sealing arrangement as claimed in claim 7, wherein the rotating and non-rotating elements and the plurality of bodies are formed together in a generative process.

9. The sealing arrangement as claimed in claim 1, wherein the plurality of bodies are interconnected by pins.

10. The sealing arrangement as claimed in claim 1, wherein the plurality of bodies support one or both of the rotating element on one or both of an inner side and on an outer side of the rotating element and the non-rotating element on one or both of an inner side and on an outer side of the non-rotating element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a sectional view through a centrifugal pump in accordance with an embodiment of the present invention,

(2) FIG. 2 shows a schematic view of an arrangement for sealing in accordance with an embodiment of the present invention,

(3) FIG. 3 shows a variant with cylindrical bodies in accordance with an embodiment of the present invention,

(4) FIG. 4 shows a variant in which the bodies are interconnected in accordance with an embodiment of the present invention,

(5) FIG. 5 shows a variant in which the bodies have a running surface both on the inside and on the outside in accordance with an embodiment of the present invention,

(6) FIG. 6 shows a schematic view of a creation of the arrangement by a generative process in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) FIG. 1 shows a centrifugal pump with an impeller 1. The impeller 1 is designed as a closed radial impeller and has a support disk 2 and a rear shroud 3. Blades are arranged on the support disk 2. Passages for the transporting of the medium are formed between the support disk 2 and the rear shroud 3. The impeller 1 is driven by a shaft 4 and is enclosed by a casing 5.

(8) The centrifugal pump has an arrangement 6 for sealing which separates a chamber 7 with a higher pressure from a chamber 8 with a lower pressure. The chamber 7 is formed in this embodiment by the second chamber of the impeller 1. The chamber 8 forms a suction side of the centrifugal pump. In the case of the arrangement 6, in this embodiment it is a split ring sealing arrangement which has a radial sealing gap.

(9) FIG. 2 shows a schematic view of an arrangement 6 for sealing. The arrangement has a non-rotating element 9 which in the view according to FIG. 2 is formed by a split ring which is arranged on the casing 5. Alternatively to the view according to FIG. 2, the non-rotating element 9 can also be formed by the casing 5 itself. Furthermore, the arrangement 6 has a rotating element 10. The rotating element 10 in the embodiment according to FIG. 2 is formed by the rear shroud of the impeller, that is to say by the impeller itself. Alternatively to the view according to FIG. 2, a rotating ring can also be arranged on the rear shroud of the impeller. A gap S is formed between the non-rotating element 9 and the rotating element 10. In the case of the gap S, it is a radial sealing gap. In order minimize as far as possible a fluid flow from the chamber with the higher pressure to the chamber with the lower pressure this gap S should be as small as possible.

(10) According to the invention, the arrangement 6 has bodies 11 which in the embodiment according to FIG. 2 are arranged on the non-rotating element 9. To this end, the non-rotating element 9 has a structure 12 in which the bodies 11 are rotatably mounted.

(11) The structure 12 is created so that the bodies 11 are embedded therein a form-fitting manner so that a part of the bodies 11 is arranged in a cavity which is formed by the structure 12 and a part of the bodies 11 project toward the gap S. The bodies 11 prevent the effect of wear phenomena occurring between both elements 9, 10 by rolling movements of the non-rotating element 9 on the rotating element 10. In the embodiment according to FIG. 2, the bodies 11 are designed as movable balls.

(12) FIG. 3 shows a variant in which the bodies are designed as movable rollers. According to the view in FIG. 3, the bodies 11 are arranged in a non-rotating element 9 which is designed as a split ring which has a structure which forms cavities so that the bodies are contained in the cavities in a form-fitting manner and at the same time a part of the bodies projects into the gap and therefore enables a rolling movement of the bodies. In the embodiment according to FIG. 3, the bodies have a cylindrical section and roll along its generated surface. The bodies which are designed as rollers rotate around an axis. Instead of rollers, individual places can have a honeycomb or a cell structure which serves for gap loss minimization.

(13) FIG. 4 shows a variant in which the movable rollers are interconnected via pins 13. Therefore, a plurality of bodies which are designed as rollers are interconnected via the pins 13 in a rotation-resistant manner. The pins 13 are also arranged in cavities of the structure 12.

(14) FIG. 5 shows an embodiment in which the bodies have a running surface both on the inside and on the outside. Also in the view according to the FIG. 5, the bodies 11 are arranged in a non-rotating element 9 which is designed as a split ring, wherein the structure is selected so that the bodies are contained in a form-fitting manner but project both on the inner generated surface and on the outer generated surface of the split ring.

(15) FIG. 6 shows a schematic view of a build-up for a method for producing an arrangement for sealing in a centrifugal pump. A build-up material in the form of a metallic powder is applied to a base 14. The powder-form material is locally completely remelted by radiation at the respective desired points and after solidification forms a solid material layer. The base 14 is then lowered by the amount of a layer thickness and powder is deposited anew. This cycle is repeated until all the layers have been remelted. In this way, it is possible to form both the non-rotating element 9 and the rotating element 10 in one generative process, wherein according to the invention at least one element has bodies 11 which are movably mounted.

(16) 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.