Pump assembly

Abstract

The present invention relates to a pump assembly comprising: a housing (1); an insert (2) disposed at least partially in the housing (1), wherein the insert (2) includes a shaft (3) arranged in such a manner that it can be rotated by a drive about a rotation axis (A) and at least two pressure stages, each having a pressure stage housing (5, 5'); an impeller (4) disposed on the shaft (3) and surrounded by the pressure stage housing (3, 5') in each pressure stage; and a seal (12) separating a first pressure chamber (11) and a second pressure chamber (13). According to the present invention, the pressure stage housing (5') includes a first component (16) and a second component (17), wherein the first component (16) has a first region (18) with an increased inner diameter and a second region (19) with a decreased inner diameter, the second component (17) has at least one first segment (20) with a decreased outer diameter and a second segment (21) with an increased outer diameter, and the first region (18) of the first component (16) surrounds the first segment (20) of the second component (17) and at least partially surrounds the second segment (21) such that an annular chamber (25) is formed between the first component (16) and the second component (17), and the annular chamber (25) is connected to the second pressure chamber (13).

Description

Technical Field

[0001] The present invention relates to a pump assembly having: a housing; an insert disposed at least partially in the housing, wherein the insert includes a shaft arranged in a manner rotatable by a drive about a rotation axis and at least two pressure stages, each having a pressure stage housing; an impeller disposed on the shaft and surrounded by a pressure stage housing in each pressure stage; and a seal separating a first pressure chamber and a second pressure chamber. Background Technology

[0002] For example, DE 199 27 135 A1 shows a centrifugal pump assembly of this type, which is also known as a double-casing pump or a shell-casing pump.

[0003] In this type of centrifugal pump, the centrifugal pump is surrounded by a sheath-like casing. The sheath casing, which has suction and pressure connections and optionally an intermediate discharge section, is closed with a cover in a plane perpendicular to the axis. Typically, this involves multi-stage pumps, used as high-pressure and ultra-high-pressure pumps, and especially as boiler feed pumps. Multiple pressure stage casings are arranged in series sequentially along the axial direction within the sheath casing. Each pressure stage includes a pump impeller and optionally fixed guide wheels.

[0004] The individual pressure stage housings of each pressure stage are typically constructed together with the pump shaft as a continuous pump insert. The flow transition from the final guide wheel, or the final pressure stage housing, to the pressure pipe is usually achieved through a flow chamber constructed in the casing or through a separate insert for an end helix in the transition region.

[0005] Feed pumps often have multiple pressure zones within a casing that appears externally as a pressure sheath. If these pressure zones are adjacent to each other, they must be sealed relative to each other in all possible operating modes, that is, under all load conditions. This is mostly achieved by means of a dedicated static seal. However, during operation, i.e., under load, the space provided for this seal undergoes deformation or displacement relative to the unloaded state, which can lead to severe stress on the seal and potentially reduce the reliability of its sealing function. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a pump assembly of a certain type that eliminates the cause of this sealing problem, which leads to large differential deformation of the components surrounding the seal.

[0007] This objective is achieved by a pump assembly according to the features of claim 1. Advantageous designs of centrifugal pumps are the subject of the dependent claims.

[0008] According to the present invention, a pressure stage housing includes a first component and a second component, the first component having a first region with an increased inner diameter and a second region with a decreased inner diameter, the second component having at least one first segment with a decreased outer diameter and a second segment with an increased outer diameter, and the first region of the first component surrounds the first segment of the second component and at least partially surrounds the second segment, such that an annular chamber is formed between the first component and the second component.

[0009] In an advantageous manner, the outer diameter of the second section of the annular disc-shaped component and the inner diameter of the first region of the sleeve-shaped component are constructed at the area where they overlap such that the first region is spaced apart from or abuts against the second section with a very small gap, thereby preventing or limiting the inward or rotational deformation of the first region of the sleeve-shaped component towards the axis of rotation.

[0010] In a suitable manner, the second section of the annular disc-shaped component has a device for connecting the annular chamber to the second pressure chamber.

[0011] The present invention is described below, wherein a second section of the second component has a circumferential side surface in which at least one groove is provided, the groove being connected to or directly connected to the annular chamber.

[0012] In another advantageous design, the annular disc-shaped component has a third section immediately following the second section of the second component, wherein at least one axial groove extending parallel to the axis of rotation is constructed in the outer peripheral surface of the third section, the axial groove forming a channel together with the cover housing, or at least one axial bore extending parallel to the axis of rotation is constructed near the outer peripheral surface, wherein the axial groove or axial bore leads to the second pressure chamber.

[0013] In a suitable manner, a radially circumferential gap is provided at the transition from the second section to the third section, the gap being connected on one hand to at least one groove and on the other hand to at least one axial groove or at least one axial bore extending in the outer peripheral surface of the third section.

[0014] In an advantageous alternative embodiment, the second component has at least one axial bore extending substantially parallel to the axis of rotation, which connects the annular chamber directly to the second pressure chamber. Attached Figure Description

[0015] Embodiments of the present invention are shown in the accompanying drawings and described in more detail below. Wherein:

[0016] Figure 1A partial cross-sectional view of a pump assembly having a first embodiment of a pressure stage housing according to the invention is shown;

[0017] Figure 2 Showing from Figure 1 The magnified segment; and

[0018] Figure 3 In accordance with Figure 1 and Figure 2 The embodiment shown is a partial cross-sectional view of the stage housing according to the invention;

[0019] Figure 4 A partial cross-sectional view of a second embodiment of the stage housing according to the invention is shown in its installed state.

[0020] Figure 5 It shows according to Figure 4 A partial view of the stage shell in cross-section;

[0021] Figure 6 A partial cross-sectional view of a third embodiment of the stage housing according to the invention is shown in its installed state. Detailed Implementation

[0022] Figure 1 A pump assembly configured as a centrifugal pump is shown, having a housing 1. An insert 2 is at least partially arranged within the housing 1. The insert 2 includes a shaft 3 rotatably arranged about a rotation axis A by a drive device not shown, such as an electric motor. In the illustrated embodiment, a plurality of impellers 4 are arranged sequentially on the shaft 3. The impellers 4 are radial impellers in this embodiment.

[0023] The insert 2 further includes a plurality of so-called pressure stage housings 5, wherein the pressure stage housings according to the invention are marked with 5'. Each impeller 4 is surrounded by a pressure stage housing 5, or 5'. Adjacent pressure stage housings 5, 5' are adjacent to each other. The dividing seam between the pressure stage housings 5, 5' is metallically sealed in the embodiment.

[0024] A guide wheel 6 is provided in each pressure stage housing 5, 5', arranged behind the corresponding impeller 4 along the flow direction of the medium to be conveyed. The guide wheel 6 is anti-rotationally connected to the pressure stage housing 5, 5' by means of a press fit or other suitable device. A suction pipe 7 is formed in the casing housing 1, through which the operating medium enters the centrifugal pump. The operating medium exits the pump assembly through a pressure pipe 8. In the illustrated embodiment, the casing housing 1 has an intermediate output section 9. A specific portion of the conveyed medium can be conveyed to a first pressure chamber 11 and led out through the intermediate output section 9 through at least one radial opening 10 in one of the central pressure stage housings 5, which is arranged between the pressure stage housings 5, 5' and the casing housing 1. The pressure chamber 11 is separated from a second pressure chamber 13 by a seal 12, which is located near the pressure pipe 8, particularly below the flow area toward the pressure pipe 8 or inside the pressure pipe 8. Here, the pressure in the second pressure chamber 13 is at least one level higher than the pressure in the pressure chamber 11, up to n-1 times the pressure level (Stufendruck), where n represents the number of levels.

[0025] exist Figure 1 The diagram depicts a multi-stage pump assembly with six pressure stages and five pressure stage housings 5, 5'. It goes without saying that the number of pressure stages must be at least two, but can vary arbitrarily in other respects. Furthermore, it is conceivable that all pressure stages can be formed using the pressure stage housings 5' according to the invention.

[0026] As shown in the figure Figure 1 magnified fragments Figure 2 As can be seen, the sealing part 12 separates the pressure chamber 11 from the channel 15. The pressure chamber gradually narrows towards the sealing part 12 towards the narrower first annular gap 14. The channel communicates with the second pressure chamber 13 in the region of the pressure pipe 8. Furthermore, Figure 2 It is shown how the sealing part 12 works in conjunction with the cover housing 1 and the pressure stage housing 5' according to the invention, and how the guide wheel 6 and the impeller 4 mounted on the shaft 3 rotating about the rotation axis A are arranged inside the pressure stage housing 5'.

[0027] Figure 3 Shown separately according to Figure 2 The pressure stage housing 5' is constructed in a cup or can shape. The pressure stage housing 5' includes a sleeve-shaped first component 16 and an annular disc-shaped second component 17. The sleeve-shaped first component 16 has a first region 18 with an increased inner diameter and a second region 19 with a decreased inner diameter.

[0028] At the transition from the first region 18 to the second region 19 of the sleeve-shaped first component 16, the sleeve-shaped component 16 is connected to the annular disc-shaped second component 17. The two components 16 and 17 can be welded to each other or manufactured in one piece, for example by means of 3D printing. In another alternative, components 16 and 17 can be screwed together.

[0029] The annular disc-shaped component 17 has a first section 20 and a second section 21 with a peripheral side surface 22. In the illustrated embodiment, the peripheral side surface 22 is substantially columnar in shape, but also has conical sections. At least one groove 23 is provided in the peripheral side surface 22, thereby giving the section 21 a recess and a raised portion 24 with the peripheral side surface 22. In the illustrated embodiment, at least one groove 23 extends substantially parallel to the axis of rotation A.

[0030] The first region 18 of the sleeve-shaped component 16 not only surrounds the first segment 20 of the annular disc-shaped second component 17 but also partially surrounds the second segment 21. The outer diameter of the first segment 20 is smaller than the outer diameter of the second segment 21. The outer diameter of the second segment 21 of the annular disc-shaped component 17 and the inner diameter of the first region 18 of the sleeve-shaped component 16 are configured such that the first region 18 is spaced apart from or abuts against the second segment 21 with a very small gap.

[0031] Because the first segment 20 of the annular disc-shaped second component 17 has a reduced outer diameter relative to the second segment 21, an annular chamber 25 is formed there between the sleeve-shaped first component 16 and the annular disc-shaped component 17. The annular chamber 25 is connected to at least one groove 23, or in fluid technology, directly connected to the groove 23. Through the annular chamber 25, the first region 18 of the sleeve-shaped component 16 is elastically constructed with specific limits.

[0032] The peripheral side 22 of the lifting part 24 prevents or restricts the deformation of the elastic region 18 of the sleeve-shaped component 16 inward or toward the rotation axis A.

[0033] In addition, component 17 has a third section 26 immediately following the second section 21 on the side opposite to the annular chamber 25.

[0034] The outer diameter of the second section 21 is smaller than the outer diameter of the third section 26. In the exemplary embodiment shown, the third section 26 has a stepped portion that can be provided, if necessary, for securing the pressure stage housing 5' to the cover housing.

[0035] Figure 2The channel 15 shown is formed by at least one axial groove (not shown) extending axially in the outer peripheral surface 27 of the third segment 26. This axial groove cooperates with the housing 1, wherein a radial connecting groove (not shown) is provided in the region of the stepped portion, connecting the two axial groove segments to each other in the outer peripheral surface 27. Alternatively, the axial groove and the connecting groove can also be constructed in the housing 1.

[0036] Because the first region 18 of the sleeve-shaped component 16 does not completely surround the second section 21, a radially circumferential gap 28 appears at the transition from the second section 21 to the third section 26, which is connected to at least one groove 23. Furthermore, the gap 23 communicates with and is therefore connected to an axial groove extending in the axial direction in the outer peripheral surface 27 of the third section 26. Figure 2 The channel 15 shown is connected to the pressure chamber 13.

[0037] A chamfer is provided at the transition from the first region 18 to the second region 19 of the sleeve-shaped first component 16, that is, the outer diameter of the sleeve-shaped component 18 is larger than the outer diameter of the region 19, so that the sealing part 12 can be assembled without problems.

[0038] Figure 4 Another embodiment of the pressure stage housing 5' according to the invention is shown in the installed state.

[0039] Figure 5 It shows in detail Figure 4 The pressure stage housing 5' shown is illustrated. The sleeve-shaped first component 16 substantially corresponds to the pressure stage housing 5'. Figures 1 to 3 The embodiments shown do not require further explanation. The second section 21 of the second component 17 and the annular chamber 25 also substantially correspond to the embodiments described above. Figures 1 to 4 In the described embodiment, the second section has at least one groove 23, at least one lifting portion 24, and a peripheral side surface 22.

[0040] In the pressure stage housing 5' Figure 4 and Figure 5 In the embodiment shown, at least one axial borehole 29 is provided in the third section 26, which is substantially parallel to the axis of rotation A. This axial borehole communicates with the gap 28 and leads to the second pressure chamber 13 in the region of the pressure pipe 8.

[0041] In the illustrated embodiment, no stepped portion is provided in section 26, yet it is possible to achieve the desired effect. Figure 2 and Figure 3 It has a stepped section as shown in the diagram.

[0042] like Figure 6 As shown, in another embodiment of the pressure stage housing 5', at least one axial bore 29 is capable of connecting to, or directly connecting to, the annular chamber 25, and extends through the second section 21 and the third section 26 and into the second pressure chamber 13. The axial bore 29 thus connects the annular chamber 25 directly to the second pressure chamber 13 in the region of the pressure connector 8. Here, the groove in the circumferential side 22 can be omitted.

[0043] In the exemplary embodiment shown, the third section 26 has a stepped portion; however, for the pressure stage housing 5'... Figure 4 and Figure 5 The type of fastening shown does not require a step.

[0044] When the pump assembly is started, the medium is drawn into the pump through the suction pipe 7 and flows toward the pressure stage housing 5, which is connected downstream of the suction pipe as the first pressure stage housing in terms of fluid flow technology. The medium is guided to the next pressure stage housing 5 by means of the impeller 4 through the guide wheel 6, which is connected downstream in terms of fluid flow technology. A portion of the medium is delivered to the pressure chamber 11 through at least one opening 10 in the stage housing 5 closest to the intermediate output 9, where the medium can be delivered from the pump through the intermediate output 9. The majority of the medium is supplied to the next pressure stage housing 5 in a corresponding manner.

[0045] In terms of fluid flow technology, the final guide wheel 6 delivers the medium into the pressure chamber 13. From there, a portion of the medium follows... Figures 1 to 3 It enters at least one groove 23 in the second section 21 through at least one channel 15 and a radially circumferential gap 28 and subsequently enters the annular chamber 25; or according to Figure 4 and Figure 5 It enters at least one groove 23 through at least one axial bore 29 and a radially circumferential gap 28, and then enters the annular chamber 25; or according to Figure 6 The pressure chamber 13 enters the annular chamber 25 directly through at least one axial bore 29. The pressure chamber 13, together with at least one channel 15 or at least one axial bore 29, a radially circumferential gap 28, at least one groove 26, and the subsequent annular chamber 25, forms a medium-filled system of communicating chambers.

[0046] An overpressure is applied in the annular chamber 25 relative to the chamber 11, which widens the region 18 and thereby abuts radially against the housing. Thus, the radial extension of the sealed chamber remains almost constant in all operating conditions.

Claims

1. A pump assembly comprising: - Cover housing (1) - an insert (2) arranged at least partially in the casing (1), wherein The insert (2) includes a shaft (3) arranged so as to be rotatable by a drive device about a rotation axis (A) and at least two pressure stages, each with a pressure stage housing (5, 5'). - Impellers (4) arranged on the shaft (3) and surrounded by the pressure stage housing (5, 5') in each pressure stage, and - A sealing part (12) that separates the first pressure chamber (11) from the second pressure chamber (13). Its features are, - The pressure stage housing (5') includes a first component (16) and a second component (17). - The first component (16) has a first region (18) with an increased inner diameter and a second region (19) with a decreased inner diameter. - The second component (17) has at least one first segment (20) with a reduced outer diameter and a second segment (21) with an increased outer diameter, and - A first region (18) of the first component (16) surrounds a first segment (20) of the second component (17) and at least partially surrounds a second segment (21), such that an annular chamber (25) is formed between the first component (16) and the second component (17), and the annular chamber (25) is connected to the second pressure chamber (13). The outer diameter of the second section (21) of the second component (17) and the inner diameter of the first region (18) of the first component (16) are configured such that the first region (18) is spaced apart from or abuts against the second section (21) with a very small gap.

2. The pump assembly of claim 1, wherein, The second component (17) has devices (15, 23, 29) for connecting the annular chamber (25) to the second pressure chamber (13).

3. The pump assembly of claim 2, wherein, The second section (21) of the second component (17) has a peripheral side surface (22) in which at least one groove (23) is provided, the groove being connected to the annular chamber (25).

4. The pump assembly of claim 2 or 3, wherein, The second component (17) has a third section (26) immediately following the second section (21) of the second component (17), wherein at least one axial groove is constructed in the outer peripheral surface (27) of the third section (26) extending parallel to the axis of rotation (A), or at least one axial bore (29) is constructed in the outer peripheral surface (27) extending parallel to the axis of rotation (A), wherein the axial groove and the axial bore (29) lead to the second pressure chamber (13).

5. The pump assembly of claim 4, wherein, A radially circumferential gap (28) is provided at the transition from the second section (21) to the third section (26), the gap being connected on one hand to the at least one groove (23) and on the other hand to the at least one axial groove or the at least one axial bore (29) extending in the outer peripheral surface (27) of the third section (26).

6. The pump assembly of claim 1 or 2, wherein, The second component (17) has an axial bore (29) that connects the annular chamber (25) directly to the second pressure chamber (13).

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