Centrifugal Pumps

Abstract

The present application relates to a centrifugal pump, comprising: a pump shaft (11); an impeller assembly (100) driven by the pump shaft (11) to rotate around an axial direction (Z), the impeller assembly (100) comprising an impeller hub (110) and an impeller (120), a stainless steel sheath (140) being circumferentially attached to the lower portion of an outer peripheral surface (114) of the impeller hub (110), a tungsten steel attachment (150) being attached to the lower end surface of the impeller hub (110), the radial width of the stainless steel sheath (140) being smaller than the radial width of the tungsten steel attachment (150). ) in radial width; an impeller axial support assembly (200, 200′) that axially supports the impeller assembly (110) and keeps it stationary, wherein the impeller axial support assembly includes a ceramic support member (250), wherein the ceramic support member (250) defines a stationary joint surface (254), wherein the stationary joint surface includes an outer annular stationary joint portion that is sealed with the lower end surface (142) of the stainless steel sheath (140) and an inner annular stationary joint portion that is sealed with the lower end surface (152) of the tungsten steel attachment (150).

Description

Technical Field

[0001] The present application relates to the field of centrifugal pumps, and in particular to a high-speed, high-lift multi-stage centrifugal pump for deep wells. Background Art

[0002] Deep well centrifugal pumps generally include a motor assembly and a pump body assembly having one or more impeller assemblies driven by a pump shaft to rotate. The pump shaft speed of a traditional centrifugal pump is generally around 1300rpm. If the water head output by the centrifugal pump is to reach 130m, the height of the centrifugal pump may usually reach 3m. Therefore, this deep well pump is large and very heavy.

[0003] Deep well centrifugal pumps are mostly used for agricultural irrigation, and are usually used at depths ranging from 110m to 500m underground. In applications with harsh natural environments such as high mountains, operation is very inconvenient. In particular, just for the transportation of centrifugal pumps, workers need to carry them to the top of the mountain, which may take several hours or even a day. It is very difficult to install a large and bulky centrifugal pump at the bottom of a well several hundred meters deep and to perform subsequent maintenance. This greatly limits the application of centrifugal pumps.

[0004] It is hoped that the efficiency of the pump can be improved and the volume and weight of the pump can be reduced to solve or at least partially improve the above problems. Summary of the invention

[0005] The purpose of the present application is to provide a novel centrifugal pump structure, which improves the efficiency of the centrifugal pump by reducing the friction energy consumption between the rotating parts and the stationary parts in the centrifugal pump, thereby greatly reducing the volume and weight of the pump.

[0006] To this end, the present application provides a centrifugal pump, comprising:

[0007] Pump shaft;

[0008] An impeller assembly driven by a pump shaft to rotate in an axial direction, the impeller assembly comprising an impeller hub defining an axial hole for engaging the pump shaft, and an impeller attached to the impeller hub and extending radially outwardly in a spiral shape from an upper portion of an outer peripheral surface of the impeller hub, a stainless steel sheath circumferentially attached to a lower portion of the outer peripheral surface of the impeller hub, a tungsten steel attachment attached to a lower end surface of the impeller hub, and a radial width of the stainless steel sheath being smaller than a radial width of the tungsten steel attachment;

[0009] An impeller axial support assembly axially supports the impeller assembly and keeps it stationary, the impeller axial support assembly includes a ceramic support member, the ceramic support member defines a stationary joint surface, the stationary joint surface includes an outer annular stationary joint portion sealingly engaged with the lower end surface of the stainless steel sleeve and an inner annular stationary joint portion sealingly engaged with the lower end surface of the tungsten steel attachment.

[0010] In one embodiment, the tungsten steel attachment is embedded in a groove formed on the lower end surface of the impeller hub, or attached to the lower end surface of the impeller hub.

[0011] In one embodiment, the radial width of the stainless steel sheath is between 1-5 mm.

[0012] In one embodiment, the inner annular stationary engagement portion includes a plurality of notches recessed from the stationary engagement surface.

[0013] In one embodiment, the ceramic support defines an axial hole for allowing the pump shaft to pass therethrough, and the plurality of notches extend radially outward from an inner circumferential surface of the ceramic support defining the axial hole.

[0014] In one embodiment, the plurality of notches are evenly spaced apart in a circumferential direction around the axial direction.

[0015] In one embodiment, the depth of the plurality of notches recessed from the stationary joint surface into the ceramic support is between one quarter and one half of the axial thickness of the ceramic support.

[0016] In one embodiment, the centrifugal pump comprises a plurality of the impeller assemblies.

[0017] In one embodiment, when the impeller assembly is the first impeller assembly at the bottom of the centrifugal pump, the impeller axial support assembly is an inlet seat support assembly.

[0018] In one embodiment, when the impeller assembly is an impeller assembly other than the lowermost first impeller assembly, the impeller axial support assembly is a guide vane cavity assembly, the guide vane cavity assembly also includes an outer shell and an inner shell defining a guide vane channel, and the ceramic support member defining the stationary joint surface is attached to the inner shell.

[0019] In one embodiment, the ceramic support is attached to the inner housing directly or via an intermediate piece.

[0020] In one embodiment, the outer shell and the inner shell of the guide vane cavity assembly are formed integrally or separately.

[0021] In one embodiment, the length of the sleeve extending axially along the lower portion of the outer circumferential surface of the impeller hub corresponds to the length of the inner circumferential surface of the inner casing surrounding the impeller hub extending in the axial direction.

[0022] The centrifugal pump of the present application includes a plurality of impeller stage groups, each impeller stage group includes an impeller assembly that performs high-speed rotation and a stationary impeller axial support assembly that axially supports the impeller assembly, wherein the impeller assembly provides an outer annular rotating joint surface having a first higher hardness and a first smaller radial width and an inner annular rotating joint surface having a second higher hardness and a second larger radial width, and the impeller axial support assembly provides a stationary joint surface including an outer annular stationary joint portion engaged with the above-mentioned outer annular rotating joint surface and an inner annular stationary joint portion engaged with the inner annular rotating joint surface, and the stationary joint surface has a lower hardness.

[0023] During the operation of the centrifugal pump, the outer annular rotating joint surface of the impeller assembly first engages with the stationary joint surface with lower hardness, and because its radial width is very small, the outer annular rotating joint surface first forms a seal by wearing the latter. Then, the "wider" inner annular rotating joint surface of the impeller assembly engages with the stationary joint surface with lower hardness to form a seal. The outer annular rotating joint surface of the impeller assembly has a very small radial width, so that the contact between it and the outer annular stationary joint part of the stationary joint surface is roughly line contact, so that the impeller assembly and the impeller axial support assembly can quickly enter the inner annular axial support contact with a larger radial width and enter a stable working state. In addition, in order to reduce the molecular force that hinders rotation between the inner annular rotating joint surface with a large radial width and the inner annular stationary joint surface, and reduce the energy loss caused thereby, the present application is provided with a plurality of recessed notches in the inner annular stationary joint part provided by the impeller assembly axial support assembly, thereby improving the efficiency of the centrifugal pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The foregoing and other features, advantages and benefits of the present application will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments of the present application. It should be understood that the drawings are not drawn to scale and are only used to illustrate the principles of the present application, and are not intended to limit the present application to the detailed structures shown in the drawings. In addition, the components shown in the drawings do not necessarily exist in all embodiments of the present application, and components not shown in the drawings may exist in some embodiments of the present application.

[0025] Figure 1 is a partially exploded perspective view of an exemplary centrifugal pump of the present application, wherein the arrangement of the impeller stage group of the pump body assembly of the centrifugal pump is emphasized;

[0026] Figure 2 Shown in Figure 1 A cross-sectional view of the structural details of the impeller assembly and the impeller axial support assembly of the impeller stage group B3 marked in the centrifugal pump;

[0027] Figure 3a-3c for Figure 1 and Figure 2Different views of the stationary support in the impeller axial support assembly. DETAILED DESCRIPTION

[0028] The centrifugal pump of the present application is described in detail below with reference to the accompanying drawings. Throughout the drawings, parts with the same or similar structure or function have the same reference numerals.

[0029] refer to Figure 1 The centrifugal pump of the present application generally includes a motor assembly 10 and a pump body assembly 20. The motor assembly 10 mainly includes a motor housing and a motor accommodated in the motor housing and capable of outputting a high speed. The construction and structural details of the motor assembly 10 are not the focus of the present application. In order to highlight the key points, Figure 1 The motor assembly 10 is only schematically shown in the figure, and its internal details are not shown. The pump body assembly 20 includes a pump sleeve 22 and at least one, for example, a plurality of impeller stage groups accommodated in the pump sleeve 22. The pump shaft 11 extends from the motor assembly 10 to transmit the rotational motion output by the motor to the impeller assemblies of each impeller stage group in the pump body assembly 20. The pump shaft 11 defines an axial direction Z including an upward direction and a downward direction.

[0030] The centrifugal pump of the present application is usually placed vertically when in use. Therefore, the directional terms used in the description of the present application are all referenced to the working state after being assembled in the centrifugal pump and placed vertically. For example, the "upper" part or "upper" side, or the "lower" part or "lower" side respectively refer to the upper part or the upper part, or the lower part and the lower part of the component after the component is assembled into the centrifugal pump and when the assembled centrifugal pump is in the vertical working state.

[0031] In the axial direction Z, from bottom to top, the pump assembly 20 includes: a water inlet section closest to the motor assembly 10, for example, Figure 1 In the exploded view of FIG. 1 , the section includes a water inlet section 32 of the pump sleeve 22 including a water inlet hole 31, and various components contained in the water inlet section 32 of the pump sleeve 22, including, but not limited to, a connection structure for connecting the pump shaft 11 to the motor output shaft, etc.; an impeller section composed of a plurality of impeller stage groups B1-B5 arranged in series up and down, for example, Figure 1 In the exploded view of the 5-stage exemplary centrifugal pump, the section includes the middle section 34 of the pump sleeve 22, and the impeller stage groups B1-B5 accommodated in the middle section 34 of the pump sleeve 22, wherein the first impeller stage group B1 is adjacent to the water inlet section, and the second to fifth impeller stage groups B2, B3, B4 and B5 are arranged in series from bottom to top; and the water outlet section is located at the opposite end of the water inlet section, for example, Figure 1 In the exploded view of , the section includes the water outlet section 36 of the pump sleeve 22, and various components accommodated in the water outlet section 36 of the pump sleeve 22, such as the water outlet cavity body assembly 42, an optional one-way valve assembly not shown in the figure, etc.

[0032] During the operation of the centrifugal pump, the motor drives the pump shaft 11 to rotate, and water enters the centrifugal pump through the water inlet hole 31 of the water inlet section. The impeller assembly in the series-arranged impeller stage group rotates at high speed to transport the water to the water outlet section, and leaves the centrifugal pump through the water outlet cavity assembly 42.

[0033] Typically, in a centrifugal pump including a plurality of impeller stage groups B1-B5 as shown in the figure, for the other impeller stage groups B2-B5 except the first impeller stage group B1 adjacent to the water inlet section, each impeller stage group includes an impeller assembly 100 driven by the pump shaft 11 to rotate together, a guide vane cavity assembly 200 surrounding the lower part of the impeller assembly 100 and providing axial support, and a support body assembly 300 surrounding the upper half of the impeller assembly 100 and providing support thereto. The first impeller stage group B1, i.e., the lowermost impeller stage group, has a slightly different structure because it is adjacent to and connected to the water inlet section of the pump body assembly 20. The impeller assembly 100 of the first impeller stage group B1 also includes a support body assembly 300 surrounding its upper part. The difference is that the lower part of the impeller assembly 100 is axially supported by an inlet seat assembly 200' having a structure slightly different from that of the guide vane cavity assembly 200.

[0034] Although the inlet seat assembly 200' that provides axial support for the impeller assembly 100 of the first impeller stage group B1 is different in structure from the guide vane cavity assembly 200 that provides axial support for the impeller assembly 100 of other impeller stage groups B2-B5, the axial engagement and support structure between the inlet seat assembly 200' for the first impeller stage group B1 and the impeller assembly 100 of the first impeller stage group B1 are the same as the axial engagement and support structure between the guide vane cavity assembly 200 for other impeller stage groups B2-B5 and their impeller assemblies 100. In view of this, in the description of this article, the inlet seat assembly 200' for the first impeller stage group B1 and the guide vane cavity assembly 200 for other impeller stage groups B2-B5 are collectively referred to as "impeller axial support assembly". The focus of this application is on the engagement structure between the high-speed rotating impeller assembly 100 and the stationary impeller axial support assembly 200' or 200 in each impeller stage group B1-B5.

[0035] Specifically, in the present application, for each impeller stage group B1-B5, the impeller assembly 100 with high-speed rotation provides an inner annular rotating joint surface with a first hardness and a first radial width and an outer annular rotating joint surface with a second hardness and a second radial width, and the stationary impeller axial support assembly 200' or 200 provides a stationary joint surface with a third hardness, wherein the second radial width is much smaller than the first radial width. Herein, the term "radial width" refers to the difference between the outer ring radius and the inner ring radius in the cross section of the annular structure perpendicular to the axial direction Z. During the operation of the centrifugal pump, the inner annular rotating joint surface and the outer annular rotating joint surface are both engaged with, contacted with, and relatively sealed with the stationary joint surface for frictional movement, wherein the first hardness and the second hardness are both greater than the third hardness, and the first hardness and the second hardness may be equal or unequal. In the exemplary embodiment provided in the present application, the first hardness is provided by a rotating joint of tungsten steel material; the second hardness is provided by a sheath of stainless steel material; and the third hardness is provided by a stationary support seat of ceramic material. Those skilled in the art should understand that the above materials are merely examples, and the present application is not limited to the above materials. Furthermore, in the present application, the stationary engagement surface is provided with a plurality of notches arranged in the circumferential direction in the inner annular stationary engagement portion that contacts the inner annular rotating engagement surface.

[0036] Reference below Figure 2 The principles of the present application are described in detail.

[0037] Figure 2 The cross-sectional view shows Figure 1 The impeller stage group B3 marked in FIG. 1 includes an impeller assembly 100 and an impeller axial support assembly, namely a guide vane cavity assembly 200 .

[0038] The impeller assembly 100 mainly includes an impeller hub 110, an impeller 120 and an impeller seat 130. The impeller hub 110 is generally cylindrical and defines an axial hole 112 that allows the pump shaft 11 of the centrifugal pump to pass through and engage with the impeller hub 110. Generally, the impeller hub 110 and the pump shaft 11 can be engaged by a key engagement. Figure 2 The keyway in the shaft hole 112 is schematically shown in FIG.

[0039] The impeller 120 extends radially outward from the upper portion of the outer circumferential surface 114 of the impeller hub 110 and spirally toward the upper end. The impeller seat 130 is located radially outside the impeller 120 and surrounds the outer circumference of the impeller 120. An impeller channel 125 is formed between the impeller 120 and the impeller seat 130 to allow water to flow through. In one embodiment of the present application, the impeller 120 and the impeller hub 110 are formed integrally, and the impeller seat 130 is attached to the outer circumference of the impeller 120 in any manner known in the art to rotate with the impeller 120. It will be understood by those skilled in the art that the impeller hub 110, the impeller 120 and the impeller seat 130 can be formed separately and then attached together, or at least two or three of them can be formed integrally.

[0040] A sleeve 140 is attached to the lower portion of the outer circumferential surface 114 of the impeller hub 110, and an anti-wear attachment 150 is attached to the lower end surface of the impeller hub 110. The manner in which the sleeve 140 and the anti-wear attachment 150 are attached to the outer circumferential surface 114 and the lower end surface of the impeller hub 110 may include, but is not limited to, any known connection manner in the art such as interference fit and connection with fasteners. As mentioned above, the sleeve 140 may be formed of a stainless steel material; the anti-wear attachment 150 may be made of tungsten steel or a similar material. In the present application, in the axial direction, the lower end surface 142 of the sleeve 140 is flush with the lower end surface 152 of the anti-wear attachment 150, but preferably extends slightly beyond the lower end surface 152 of the anti-wear attachment 150, for example, by 1-2 mm. The lower end surface 142 of the sleeve 140 and the lower end surface 152 of the anti-wear attachment 150 provide the above-mentioned outer annular rotating joint surface and inner annular rotating joint surface, respectively. In the embodiment in which the anti-wear attachment 150 is retained in an embedded manner in a groove formed on the lower end surface of the impeller hub 110 as shown in the figure, the outer annular rotational engagement surface and the inner annular rotational engagement surface provided by the lower end surface 142 of the sleeve 140 and the lower end surface 152 of the anti-wear attachment 150, respectively, are radially separated. However, it is conceivable that if the anti-wear attachment 150 is attached to and extends to cover the entire lower end surface of the impeller hub 110, the outer annular rotational engagement surface and the inner annular rotational engagement surface provided by the lower end surface 142 of the sleeve 140 and the lower end surface 152 of the anti-wear attachment 150, respectively, may be continuous.

[0041] The impeller axial support assembly 200 includes a support member assembly 300 (only in Figure 11 and 2 , the outer casing 210 mechanically engaged with the impeller stage 100 is shown in the figure, and the inner casing 220 tightly surrounds the lower part of the impeller stage 100, that is, the jacket 140 of the impeller stage 100, and the guide vane 230 spirally extends between the inner casing 220 and the outer casing 230 to form a guide vane channel 225 that allows water to flow through. The guide vane channel 225 of each impeller stage 100 is in fluid communication with the impeller channel 125, and the impeller channel 125 of the adjacent impeller stage 100 is in fluid communication with the guide vane channel 225, so that water can enter from the water inlet section of the pump body assembly 20, flow through each guide vane channel 225 and the impeller channel 125 of each impeller stage 100 arranged in series up and down, and flow out through the water outlet section.

[0042] In the illustrated embodiment, the intermediate member 240 is fixedly attached to the inner housing 220, and the stationary support seat 250 that directly supports and contacts the impeller assembly 100 is attached to the intermediate member 240 and remains stationary during the operation of the centrifugal pump. The intermediate member 240 and the stationary support seat 250 respectively define shaft holes 242 and 252 that allow the pump shaft to pass through. The stationary support seat 250 includes an upper surface 254 that serves as the above-mentioned stationary engagement surface.

[0043] like Figure 2 As shown, in the assembled state of the impeller assembly 100 and the impeller axial support assembly 200, the lower end surface 142 of the sleeve 140 and the lower end surface 152 of the anti-wear attachment 150 are both engaged with the upper surface 254 of the stationary support seat 250. In other words, the upper surface 254 of the stationary support seat 250 includes an outer annular stationary engagement portion engaged with the lower end surface 142 of the sleeve 140 and an inner annular stationary engagement portion engaged with the lower end surface 152 of the anti-wear attachment 150. Corresponding to the outer annular rotational engagement surface and the inner annular rotational engagement surface, the outer annular stationary engagement portion and the inner annular stationary engagement portion of the upper surface 254 of the stationary support seat 250 are also discontinuous. However, in other embodiments not shown, they may be continuous.

[0044] During operation of the centrifugal pump, the lower end surface 142 of the jacket 140 and the lower end surface 152 of the anti-wear attachment 150 engage the upper surface 254 of the stationary support seat 250 simultaneously, or preferably prior to the lower end surface 152 of the anti-wear attachment 150. Figure 2 ) is small enough, for example, between 1-5 mm, preferably between 2-4 mm, and more preferably 3 mm, it can be considered that the contact between the sleeve 140 and the stationary support seat 250 is an annular "line" contact, which makes the high-speed rotating sleeve 140 quickly wear the upper surface 254 of the stationary support seat 250, that is, the outer annular stationary engagement portion, thereby quickly forming a seal between the impeller assembly 100 and the impeller axial support assembly 200 before the contact between the inner annular stationary engagement portion with a larger radial width and the inner annular rotating engagement surface forms a seal.

[0045] As the outer annular stationary engagement portion of the upper surface 254 of the stationary support seat 250 is worn, the contact between the lower end surface 152 of the anti-wear attachment 150 of the impeller assembly 100 and the upper surface 254 of the stationary support seat 250, specifically the inner annular stationary engagement portion, gradually becomes tighter. At the same time, all the axial forces exerted on the impeller assembly 100 are transmitted to the impeller axial support assembly 200, and the lower end surface 152 of the anti-wear attachment 150 and the upper surface 254 of the stationary support seat 250 form a substantially sealed friction contact.

[0046] When the sealed end face 152 and surface 254 rotate at a relatively high speed and a vacuum is formed therebetween, it is easy for a molecular binding force to be generated between the materials forming the two end faces, which hinders the relative movement of the two. In order to eliminate or at least reduce the generation of this undesirable force to a great extent, the present application forms a notch-type groove 262 on the one with smaller hardness among the mutually engaged end face 152 and surface 254, i.e., the stationary end face 254. The formation of the groove 262 destroys the vacuum formed between the mutually engaged surfaces, affects the formation of the above-mentioned molecular force, and is beneficial to reducing the resistance that hinders the relative rotation between the two, thereby correspondingly reducing energy loss and improving the efficiency of the centrifugal pump.

[0047] Figure 3a-3c The notch 262 formed on the upper surface 254 of the stationary support seat 250 is clearly shown. Figure 3a is a three-dimensional diagram of the stationary support seat 250, Figure 3c is a top view of the stationary support seat 250, Figure 3b For along Figure 3c A cross-sectional view along line XX.

[0048] As can be seen from the figure, a plurality of notches 262 are provided on the upper surface 254 of the stationary support seat 250 along the circumferential direction around the axial direction Z, and are preferably evenly arranged around the shaft hole 252. The notches 262 are recessed downward from the upper surface 254 into the interior of the stationary support seat 250, extend radially outward from the inner circumferential surface defining the shaft hole 252, and terminate at a position radially inward of the outer annular stationary engagement portion, or are substantially located within the inner annular stationary engagement portion engaged with the lower end surface 152 of the anti-wear attachment 150.

[0049] The number of the notches 262 is not limited to 8 as shown in the figure, and can be any number evenly arranged along the circumferential direction.

[0050] The shape of the slot 262 is not limited to the substantially oblong shape shown in the figure. In the illustrated exemplary embodiment, the slot 262 has substantially parallel side surfaces 272, a substantially arc-shaped radial outer end surface 274, and a substantially concave curved bottom surface 276. Alternatively, the slot 262 may have a circular shape, an elliptical shape, any polygonal shape, any irregular shape, or a combination of any two or more of the foregoing shapes.

[0051] The extension direction of the slot 262 is not limited to the radial direction shown in the figure, but can be modified according to actual needs to extend in a spiral shape, extend in a circumferential direction, extend obliquely in any direction, extend in a winding manner, etc.

[0052] The size of the slot 262 can also be set as needed. In the illustrated embodiment, the radial extension of the slot 262 is limited to the inner annular stationary engagement portion. The depth d of the slot 262 extending into the stationary support seat 250 can be between one quarter and one half of the total thickness D of the stationary support seat 250, preferably about one third.

[0053] Those skilled in the art should also understand that, without departing from the principles of the present application, the present application is not limited to the structure in which the stationary support seat 250 is completely embedded in the recess of the middle piece 240 as shown in the figure, and the stationary support seat 250 can be partially embedded in the middle piece 240, or can be attached to the upper surface of the middle piece 240. Optionally, the middle piece 240 can be omitted, so that the stationary support seat 250 can be directly attached to the inner shell 220. In one embodiment, the stationary support seat 250 can be an annular member directly embedded in the inner shell 220.

[0054] Those skilled in the art should also understand that the stationary support seat 250 and the anti-wear attachment 150 are not limited to the annular planar structure shown in the figure, but can have any suitable structure, as long as an annular rotating or stationary engagement surface or engagement portion having the hardness, material and size characteristics of the present application is provided. For example, the stationary support seat 250 and the anti-wear attachment 150 can have any other shape or structure, such as including a hook or any other engagement feature for attachment to the inner casing 220 or the impeller hub 110.

[0055] As described above, the attachment method of the stainless steel sheath 140 and the tungsten steel anti-wear attachment 150 to the impeller hub 110 and the attachment method of the intermediate piece 240 and the stationary support seat 250 to the inner casing 220 can be changed as needed and is not limited to the details shown in the figure.

[0056] It is also conceivable that, instead of the upper surface 254 of the stationary support seat 250 formed of ceramic material as shown in the figure engaging with the impeller assembly 100, the upward surface of the intermediate member 240 (if the stationary support seat 250 is not provided) to which a certain thickness of ceramic material is applied (e.g., sprayed) or the upward surface of the inner shell 220 (if the intermediate member 240 and the stationary support seat 250 are not provided) to which a certain thickness of ceramic material is applied (e.g., sprayed) can be used to provide an axial support surface engaged with the impeller assembly 100. Similarly, the stainless steel jacket 140 and the anti-wear attachment 150 of the impeller assembly 100 can also be omitted, and the lower end surface 142 and the lower end surface 152 shown in the figure can be provided by applying or spraying a coating of corresponding materials to certain parts of the impeller hub 110.

[0057] In the illustrated embodiment, the jacket 140 of the impeller assembly 100 is further configured to effectively separate the high-speed rotating impeller hub 110 from the inner circumferential surface 222 ( Figure 2 Thus, the length of the jacket 140 extending along the axial direction Z substantially corresponds to or is approximately equal to the axial length of the inner casing 220 surrounding the impeller hub 110 .

[0058] Although this application refers to Figure 1 A centrifugal pump comprising five impeller stage groups is described, but the present application is by no means limited to a centrifugal pump comprising five impeller stage groups, and the centrifugal pump may include one, two, three, four, six or more impeller stage groups.

[0059] Although the present invention is described above with reference to the embodiments shown in the drawings, it is apparent to one of ordinary skill in the art that other embodiments and examples may perform similar functions and / or achieve similar results. It is thus contemplated that all such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following non-limiting claims for all purposes.

Claims

1. A centrifugal pump, characterized in that: include: Pump shaft (11); An impeller assembly (100) driven by a pump shaft (11) to rotate about an axial direction (Z), the impeller assembly (100) comprising an impeller hub (110) defining an axial hole (112) for engaging the pump shaft (11), and an impeller (120) attached to the impeller hub (110) and extending radially outwardly in a spiral shape from an upper portion of an outer peripheral surface (114) of the impeller hub (110), a stainless steel sheath (140) circumferentially attached to a lower portion of the outer peripheral surface (114) of the impeller hub (110), a tungsten steel attachment (150) attached to a lower end surface of the impeller hub (110), and a radial width of the stainless steel sheath (140) being smaller than a radial width of the tungsten steel attachment (150); An impeller axial support assembly (200, 200') axially supports an impeller assembly (100) and keeps it stationary, the impeller axial support assembly comprising a ceramic support member (250), the ceramic support member (250) defining a stationary joint surface (254), the stationary joint surface comprising an outer annular stationary joint portion sealingly engaged with a lower end surface (142) of a stainless steel sheath (140) and an inner annular stationary joint portion sealingly engaged with a lower end surface (152) of a tungsten steel attachment (150), The tungsten steel attachment (150) is embedded in a groove formed on the lower end surface of the impeller hub (110). The inner annular stationary joint portion includes a plurality of notches (262) recessed from the stationary joint surface, wherein the ceramic support member (250) defines an axial hole (252) allowing the pump shaft (11) to pass through, and the plurality of notches (262) extend radially outward from the inner circumferential surface of the ceramic support member (250) defining the axial hole (252).

2. The centrifugal pump according to claim 1, characterized in that: The radial width of the stainless steel sheath (140) is between 1 and 5 mm.

3. The centrifugal pump according to claim 1, characterized in that: The plurality of notches (262) are evenly spaced apart in a circumferential direction around the axial direction (Z).

4. The centrifugal pump according to claim 1, characterized in that: The depth (d) of the plurality of notches (262) recessed from the stationary joint surface into the ceramic support (250) is between one quarter and one half of the axial thickness (D) of the ceramic support (250).

5. The centrifugal pump according to any one of claims 1 to 4, characterized in that: The centrifugal pump includes a plurality of impeller assemblies.

6. The centrifugal pump according to claim 5, characterized in that When the impeller assembly is the first impeller assembly at the bottom of the centrifugal pump, the impeller axial support assembly is an inlet seat support assembly (200').

7. The centrifugal pump according to claim 5, characterized in that When the impeller assembly is an impeller assembly other than the first impeller assembly at the bottom, the impeller axial support assembly is a guide vane cavity assembly (200), the guide vane cavity assembly further comprising an outer casing (210) and an inner casing (220) defining a guide vane channel (225), and a ceramic support member (250) defining the stationary joint surface (254) is attached to the inner casing (220).

8. The centrifugal pump according to claim 7, characterized in that The ceramic support member (250) is directly attached to the inner housing (220) or attached to the inner housing (220) via an intermediate member (240).

9. The centrifugal pump according to claim 7, characterized in that: The outer shell and the inner shell of the guide vane cavity assembly are formed integrally or separately.

10. The centrifugal pump according to any one of claims 7 to 9, characterized in that: The length of the sleeve (140) extending axially along the lower portion of the outer circumferential surface (114) of the impeller hub (110) corresponds to the length of the inner circumferential surface (222) of the inner casing (220) extending in the axial direction around the impeller hub (110).

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