CN108087291B - High-lift long-blade molded line rear cavity structure centrifugal pump - Google Patents
High-lift long-blade molded line rear cavity structure centrifugal pump Download PDFInfo
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- CN108087291B CN108087291B CN201711473054.XA CN201711473054A CN108087291B CN 108087291 B CN108087291 B CN 108087291B CN 201711473054 A CN201711473054 A CN 201711473054A CN 108087291 B CN108087291 B CN 108087291B
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- 238000007789 sealing Methods 0.000 claims abstract description 67
- 238000005192 partition Methods 0.000 claims abstract description 51
- 239000007788 liquid Substances 0.000 claims abstract description 29
- 238000012856 packing Methods 0.000 claims description 24
- 230000033001 locomotion Effects 0.000 claims description 7
- 238000009792 diffusion process Methods 0.000 claims description 6
- 230000000903 blocking effect Effects 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 239000012530 fluid Substances 0.000 description 43
- 238000013461 design Methods 0.000 description 14
- 230000010349 pulsation Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 6
- 238000004364 calculation method Methods 0.000 description 5
- 238000011160 research Methods 0.000 description 5
- 238000004088 simulation Methods 0.000 description 5
- 238000005266 casting Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 210000004907 gland Anatomy 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 241000237858 Gastropoda Species 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D13/00—Pumping installations or systems
- F04D13/02—Units comprising pumps and their driving means
- F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/08—Sealings
- F04D29/086—Sealings especially adapted for liquid pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/18—Rotors
- F04D29/22—Rotors specially for centrifugal pumps
- F04D29/2205—Conventional flow pattern
- F04D29/2222—Construction and assembly
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/18—Rotors
- F04D29/22—Rotors specially for centrifugal pumps
- F04D29/24—Vanes
- F04D29/242—Geometry, shape
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/426—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for liquid pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/44—Fluid-guiding means, e.g. diffusers
- F04D29/445—Fluid-guiding means, e.g. diffusers especially adapted for liquid pumps
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
A centrifugal pump with a high-lift long-blade molded line rear cavity structure comprises a pump shell, a volute, an impeller, a molded line partition board, an upper cavity pump body, a motor and a main shaft, wherein the pump shell is provided with a liquid inlet and a liquid outlet which can be communicated with an inner cavity of the pump shell; the volute and the pump shell are integrally formed; the impeller comprises an impeller front cover plate, an impeller rear cover plate, an impeller hub and a plurality of blades; the molded line baffle sealing cover is arranged at the mounting opening of the pump shell; the bottom of the upper cavity pump body is fixedly connected with the molded line partition board, the upper part of the upper cavity pump body is fixedly connected with a chassis of the motor, an output shaft of the motor stretches into the upper cavity pump body, a shaft head of the output shaft is fixedly connected with the upper end of the main shaft through a coupler, the lower end of the main shaft penetrates through a central through hole of the molded line partition board and then stretches into a volute chamber of the volute, an impeller is fixedly arranged on the shaft head of the main shaft, and the central shaft of the impeller is kept coincident with the central shaft of the main shaft. The beneficial effects of the invention are as follows: high lift and high stability are realized; forms a stable vortex, improves the stability of the pump during operation, and reduces the hydraulic loss to a certain extent.
Description
Technical Field
The invention relates to a high-lift and high-stability vertical centrifugal pump with a long-blade type linear rear cavity structure and a backflow front cavity structure, in particular to a high-lift and long-blade type linear rear cavity structure centrifugal pump.
Background
The impeller is a core flow-through component of the centrifugal pump, and blades on the impeller play a role in acting on fluid; the volute is a short for the volute type water diversion chamber, and the appearance is similar to that of a snail shell, so the volute is generally called a volute for short, and liquid flowing out of the impeller is collected and evenly led to a discharge section of the pump or an inlet of a secondary impeller. In the conventional process, the impeller and the volute are respectively designed and processed, and the relevant dimension is designed only at the matching position, so that a large amount of vortexes and uncontrollable factors are generated in the process of fluid from the impeller to the volute, and meanwhile, the fluid reaching the volute flows back due to the existence of a partition tongue, so that a certain efficiency and a certain lift loss are caused.
For the research of fluid flow in a pump, theoretical analysis and experimental research are two important research methods, but a single method cannot meet the requirements of engineering research. Because of the complexity of the actual flowing process, most problems cannot obtain results through theoretical analysis, so that engineering limitation of a theoretical analysis method is caused, however, the test cost is high, the test conditions are difficult to ensure, and the like, so that the cost performance of test research is low and the implementation is difficult. With rapid development of computers and continuous maturity of approximation algorithms, numerical calculation methods become a third class of methods for researching fluid flow, and are continuously new, forming an independent subject branch, namely computational fluid dynamics. The numerical calculation method relates to a plurality of scientists such as mathematical equations, computational mathematics and the like, and essentially solves a flow differential equation by using the numerical calculation method, and finally obtains the approximate values of the related parameters such as pressure, speed and the like on the limited points in the flow field. The CFD numerical calculation method works in coordination with the test, not only provides quantitative comparison, but also can scientifically explain the basic phenomenon in the test, and becomes a widely used technical means for water pump researchers.
Disclosure of Invention
In order to reduce the axial force of the centrifugal pump and simultaneously systematically improve the lift and stability of the pump, the invention provides the high-lift long-blade molded line rear cavity structure centrifugal pump of the high-lift high-stability vertical centrifugal pump which is provided with a backflow front cavity and has a linear rear cavity structure on the basis of performing three-dimensional turbulence numerical simulation on an impeller inner runner.
The invention relates to a centrifugal pump with a high-lift long-blade molded line rear cavity structure, which is characterized in that: the device comprises a pump shell, a volute, an impeller, a molded line partition board, an upper cavity pump body, a motor and a main shaft, wherein the pump shell is provided with a liquid inlet and a liquid outlet which can be communicated with an inner cavity of the pump shell; the volute and the pump shell are integrally formed, a first central hole and a second central hole are respectively formed in two sides of a spiral line segment of the volute, the first central hole is communicated with the liquid inlet through the liquid inlet flow channel, and the second central hole of the volute is communicated with the mounting opening at the upper end of the pump shell; the diffusion section of the volute is used as a liquid outlet flow channel to be communicated with a liquid outlet of the pump shell;
the impeller is arranged in a volute chamber of the volute, and is fixedly arranged on a shaft head of the main shaft extending into the volute chamber, the impeller comprises an impeller front cover plate, an impeller rear cover plate, an impeller hub and a plurality of blades, the blades are circumferentially arranged along the impeller hub, and the impeller front cover plate and the impeller rear cover plate are respectively arranged on the front side and the rear side of the blades and are connected with the blades; the central through hole of the impeller rear cover plate extends outwards along the axial direction of the central through hole to form an impeller hub; the impeller front cover plate and the inner wall of the pump shell at the same side form a circular backflow front cavity, and an axial gap and a circumferential gap are respectively reserved at the inner boundary and the outer boundary of the backflow front cavity, wherein the axial gap is a gap between the central suction inlet end face of the impeller front cover plate and the inner end face of the liquid inlet channel; the circumferential gap is a gap between the surface of the outer end part of the impeller front cover plate and the bulge of the inner wall of the volute;
the molded line baffle sealing cover is arranged at the mounting opening of the pump shell, a central through hole of the molded line baffle extends outwards along the axial direction to form a molded line baffle hub for mounting the main shaft, wherein the outer end part of the molded line baffle hub is connected with the main shaft in a sealing and rotating way, so that the main shaft rotates around the central shaft of the main shaft in the circumferential direction, and the rest part of the molded line baffle hub is in clearance fit with the main shaft penetrating through the molded line baffle hub, and the clearance is an annular clearance; an arc-shaped gap which can be communicated with the annular gap is reserved between the inner end surface of the molded line partition plate and the impeller rear cover plate, and the arc-shaped gap is communicated with the annular gap to form a rear cavity structure of the centrifugal pump; the molded line partition board is provided with a pressure relief hole which can be communicated with the rear cavity structure;
the bottom of the upper cavity pump body is fixedly connected with the molded line partition board, the upper part of the upper cavity pump body is fixedly connected with a chassis of the motor, an output shaft of the motor stretches into the upper cavity pump body, a shaft head of the output shaft is fixedly connected with the upper end of the main shaft through a coupler, the lower end of the main shaft penetrates through a central through hole of the molded line partition board and then stretches into a volute chamber of the volute, an impeller is fixedly arranged on the shaft head of the main shaft, and the central shaft of the impeller is kept coincident with the central shaft of the main shaft.
The length of the blades of the existing impeller is flush with the front cover plate and the rear cover plate, the distance from the front cover plate to the center of the impeller is L, and the distance from the top ends of the blades to the center of the impeller is L' after the blades are lengthened and modified. The lengthened distance between the modified L' and the L is one third of the distance w between the front cover plate and the rear cover plate and the partition tongue.
The inner end face of the molded line partition plate is parallel to the outer surface of the impeller back cover plate, namely the radian of the inner end face is consistent with that of the impeller back cover plate, so that a uniform arc-shaped gap is reserved between the molded line partition plate and the impeller back cover plate.
The sealing device comprises a packing for sealing, a sealing element for blocking the leakage of the packing and a sealing end cover for limiting the axial movement of the main shaft, wherein the sealing element is sleeved at the outer end part of the annular gap, the packing for sealing is filled in a sealing cavity of the sealing element, and the packing is in direct contact with the outer wall of the main shaft; the sealing device is characterized in that an annular bulge for limiting the axial movement of the sealing element is arranged on the main shaft, a through hole for the main shaft to penetrate is formed in the sealing end cover, the sealing end cover is fixedly arranged on the end face of the outer end part of the molded line partition plate hub, and the sealing device is axially fixed through the sealing end cover sleeved on the main shaft and the annular bulge on the main shaft.
The inner end surface of the molded line partition plate is provided with a step surface which can be matched with the step surface at the mounting opening of the pump shell along the circumferential direction of the inner end surface, sealing rings are clamped at the two step surfaces, and the pump shell and the molded line partition plate are fastened through corresponding bolts.
The main shaft is vertically arranged, external threads are machined at the shaft head of the lower end of the main shaft, the shaft head of the main shaft sequentially penetrates through the impeller hub and the gasket of the impeller and then is screwed with the shaft head nut, the axial fixation of the impeller and the main shaft is realized through the shaft shoulder and the shaft head nut of the main shaft, the inner wall of the impeller hub is connected with the main shaft key, and the circumferential fixation of the impeller hub and the gasket is realized.
The bottom end face of the upper cavity pump body is provided with a bulge, the upper end face of the molded line partition board is provided with a clamping part which can be matched with the bulge, and the bulge and the molded line partition board are fastened through bolts.
The pump shell, the impeller and the molded line partition plate are manufactured by stamping and welding or casting, the pump manufactured by stamping and welding has small surface roughness and very thin blades, the hydraulic performance of the pump is far higher than that of a casting pump, the requirements of precision manufacturing can be met, the casting production efficiency is high, the production cost is low, and different preparation methods can be selected according to different engineering requirements. The molded line type partition plate is matched with the pump shell through a step surface, and a sealing ring is additionally arranged in the step surface, so that on one hand, the sealing is realized through gravity extrusion, on the other hand, the abrasion of a machine body caused by vibration is reduced, and after the molded line type partition plate is matched, the molded line type partition plate is fastened through bolts. The upper cavity pump body is positioned between the motor and the pump shell, is matched with the clamping part of the molded line partition board through a bulge, is fastened through a bolt, and is internally provided with a space for installing a shaft coupling of the motor shaft and the main shaft; the upper part is provided with a motor through a bolt, and a reinforcing ring is arranged on the wall surface of the upper cavity pump body for improving the overall stability.
The axial fixing device has the advantages that the axial fixing device is more compact and smaller in axial amplitude compared with the axial fixing of the main shaft through a bearing, and the axial fixing device has the advantages that a clearance axial gap is reserved between an impeller and a liquid inlet channel, so that the axial amplitude is very necessary to be reduced as far as possible in global design; the axial fixing of the impeller can be realized jointly through the spindle head nut and the spindle shoulder by installing the gasket and screwing the nut after the impeller is well matched, and the axial amplitude of the impeller is also reduced.
The backflow front cavity is a smooth flow channel which is formed by the impeller front cover plate and the pump shell in a surrounding mode, the backflow front cavity is similar to a circular ring, the boundary is two gaps, the gap at the inner boundary is an axial gap formed by the impeller front cover plate and the water inlet, and the gap at the outer boundary is a circumferential gap formed by the volute and the impeller front cover plate. The first clearance is also called an annular clearance, the clearance needs to be strictly controlled, the excessive clearance can cause serious reduction of efficiency of backflow, the excessive clearance can cause serious friction of an overcurrent part, the clearance is designed to be 0.1mm in a common design, and the invention also adopts the same design; however, unlike the annular gap of other types of centrifugal pumps, most of the annular gaps of the existing centrifugal pumps are radial gaps, certain radial vibration is caused due to pressure pulsation caused by non-axial symmetrical structures of the spiral casing of the centrifugal pump, the annular gap is continuously changed along with the radial vibration, the flowing state of fluid is continuously changed, and instability is caused during operation, so that the annular gap is designed to be an axial gap, and gap change caused by radial pressure pulsation of the pump and unstable flow caused by the radial pressure pulsation can be almost avoided; meanwhile, the first gap is an axial gap, so that axial pressure pulsation needs to be reduced as much as possible in the whole pump body design, a connecting mode of a main shaft and a coupler is selected to be a bolt connection mode instead of a traditional bearing, an impeller is doubly fixed through a shaft shoulder and a shaft head nut, and meanwhile, the axial pressure pulsation is reduced through a linear rear cavity structure. After the fluid enters the volute through the impeller, a small part of the fluid flows into the backflow front cavity through a gap between the impeller front cover plate and the pump shell and flows back to the liquid inlet flow channel through the axial gap, and the fluid is lost, so that the efficiency of the pump is reduced, the streamline of the water inlet is disturbed, and the fluid is reduced as much as possible; the backflow front cavity forms a relatively stable vortex by the geometric design of the front cover plate and the pump shell, and the axial clearance and the circumferential clearance are perpendicular to the flow direction of the vortex, so that only very little fluid can flow through the clearance to enter the liquid inlet channel or flow back to the volute, that is, after the centrifugal pump starts to operate, the fluid in the backflow front cavity can quickly enter a stable flow state, and little fluid exchange with other channels is realized, so that the efficiency loss caused by backflow is greatly reduced.
The long blades are the impeller blades, the length of which exceeds the front cover plate and the rear cover plate, and the length of which exceeds one third of the width of the volute diffusion section. The length increase of the long blades compared with the non-long blades means the lifting of the pump lift, because the impeller blades are the main flow passing components for doing work on the fluid, the kinetic energy and pressure energy of the fluid are improved through the rotation of the blades, the lifting of the blade length can enhance the capacity of the impeller for doing work on the fluid, the lifting of the pump lift is improved, the strength of the cast pump blades is low, the toughness is poor, the increase of the blade length can lead to the reduction of the service life of the pump, the operation stability is reduced, however, the strength of the blades is ensured for the stamping welding pump, and the pump lift is more suitable for being improved by using the long blades. Meanwhile, the streamline matching structure of the long blades and the volute can enable fluid to flow back to the impeller, so that the acting quantity of the impeller on the fluid can be increased, and the lift is further improved.
The rear cavity structure is a molded line type flow passage which is formed by a stainless steel plate which is arranged between the pump shell and the rear cavity pump body, is consistent with the molded line of the rear cover plate and is parallel to the rear cover plate of the impeller, and the impeller rear cover plate is together provided with the molded line type flow passage, and the flow passage is narrower and has strict requirements on roughness, so that the stainless steel plate is required to be selected for stamping molding. The molded line partition plate furthest reduces the volume of the pump cavity, the hydraulic design can also refer to the data of the rear cover plate of the impeller, the uniformity and the standardization are easier, the liquid flow can be better improved, and the hydraulic loss is reduced; meanwhile, due to the structure of the linear partition plate and the impeller forming a balance chamber structure, the axial pressure and the pulsation amplitude can be greatly reduced, namely, the axial clearance of the cavity before backflow can be kept stable, and the overall stability of the pump is improved.
The beneficial effects of the invention are as follows: the high lift and high stability are realized, namely, the working capacity of the impeller on the fluid is enhanced through the structural design of the long blades, so that the fluid obtains more energy through the impeller; the design of the backflow front cavity enables the fluid passing through the front cover plate and the pump shell to form stable vortex in the front cavity, and the motion direction of the vortex is vertical to the gap between the front cover plate and the pump shell and the gap between the front cover plate and the mouth ring, so that the fluid in the front cavity is hardly exchanged with the fluid in other fluid areas, the stability of the pump during operation is improved, and the hydraulic loss is reduced to a certain extent; the design of the linear partition plate can reduce the axial force and pressure pulsation received by the impeller and the main shaft, and meanwhile, the shaft coupling is directly connected with the main shaft through bolts, so that the axial amplitude of the impeller is reduced, the change of the clearance of the mouth ring is reduced, and the stability of the pump is improved.
Drawings
Fig. 1: an overall schematic of the pump;
fig. 2: an axial cross-section schematic;
fig. 3: an impeller section schematic;
fig. 4a: one of the axial section flow charts;
fig. 4b: a second axial section flow diagram;
fig. 5: pressure cloud image of impeller section.
Detailed Description
The invention is further described below with reference to the drawings.
Referring to the drawings:
the embodiment 1 of the invention relates to a centrifugal pump with a high-lift long-blade molded line rear cavity structure, which comprises a pump shell 1, a volute 10, an impeller 22, a molded line partition plate 11, an upper cavity pump body 12, a motor 13 and a main shaft 15, wherein the pump shell 1 is provided with a liquid inlet 2 and a liquid outlet 21 which can be communicated with an inner cavity of the pump shell; the volute 10 and the pump shell 1 are integrally formed, a first central hole and a second central hole are respectively formed on two sides of a spiral line segment 101 of the volute 10, the first central hole is communicated with the liquid inlet 2 through a liquid inlet channel 23, and the second central hole of the volute 10 is communicated with a mounting port at the upper end of the pump shell 1; the diffusion section 102 of the volute 10 is used as a liquid outlet channel to be communicated with a liquid outlet of the pump shell 1;
the impeller 22 is arranged in the volute chamber of the volute 10 and fixedly arranged on a shaft head of the main shaft 15 extending into the volute chamber, the impeller 22 comprises an impeller front cover plate 6, an impeller rear cover plate 8, an impeller hub 19 and a plurality of blades 7, the blades 7 are circumferentially arranged along the impeller hub 19, and the impeller front cover plate 6 and the impeller rear cover plate are respectively arranged on the front side and the rear side of the blades 7 and are connected with the blades 7; the central through hole of the impeller rear cover plate 6 extends outwards along the axial direction to form an impeller hub; the impeller front cover plate 7 and the inner wall of the pump shell 1 at the same side form a circular backflow front cavity 4, and an axial gap 3 and a circumferential gap 5 are respectively reserved at the inner boundary and the outer boundary of the backflow front cavity 4, wherein the axial gap 3 is a gap between the central suction inlet end face of the impeller front cover plate and the inner end face of the liquid inlet channel; the circumferential gap 5 is a gap between the surface of the outer end part of the impeller front cover plate and the bulge of the inner wall of the volute;
the molded line baffle 11 is sealed and arranged at the mounting opening of the pump shell 1, a central through hole of the molded line baffle 11 extends outwards along the axial direction to form a molded line baffle hub for mounting the main shaft, wherein the outer end part of the molded line baffle hub is connected with the main shaft 15 in a sealing and rotating way, so that the main shaft 15 rotates around the central shaft of the main shaft, the rest part of the molded line baffle hub is in clearance fit with the main shaft penetrating through the molded line baffle hub, and the clearance is an annular clearance; an arc-shaped gap which can be communicated with the annular gap is reserved between the inner end surface of the molded line partition plate and the impeller rear cover plate, and the arc-shaped gap is communicated with the annular gap to form a rear cavity structure 18 of the centrifugal pump; the molded line partition plate 11 is provided with a pressure relief hole 9 which can be communicated with the rear cavity structure 18;
the bottom of the upper cavity pump body 12 is fixedly connected with the molded line partition 11, the upper part of the upper cavity pump body 12 is fixedly connected with a chassis of the motor 13, an output shaft of the motor 13 extends into the upper cavity pump body 12, a shaft head of the output shaft is fixedly connected with the upper end of the main shaft 15 through a coupler 14, the lower end of the main shaft 15 penetrates through a central through hole of the molded line partition 11 and then extends into a volute chamber of the volute 10, an impeller 22 is fixedly arranged on the shaft head of the main shaft, and the central shaft of the impeller 22 is kept coincident with the central shaft of the main shaft 15.
The length L 'of the blades 7 of the impeller 22 exceeds the length L' from the front cover plate to the center of the impeller by one third of the distance w between the front cover plate and the rear cover plate and the volute 10.
The inner end surface of the molded line partition plate 11 is parallel to the outer surface of the impeller back cover plate 8, namely the radian of the inner end surface is consistent with that of the impeller back cover plate 8, so that a uniform arc-shaped gap is reserved between the molded line partition plate 11 and the impeller back cover plate 8.
A sealing device 17 is arranged between the outer end part of the molded line baffle hub and the outer wall of the main shaft 15, the sealing device 17 comprises a packing for sealing, a sealing element for blocking the leakage of the packing and a sealing end cover 16 for limiting the axial movement of the main shaft, the sealing element is sleeved at the outer end part of the annular gap, the packing for sealing is filled in a sealing cavity of the sealing element, and the packing is in direct contact with the outer wall of the main shaft; the sealing device is characterized in that an annular bulge for limiting the axial movement of the sealing element is arranged on the main shaft, a through hole for the main shaft to penetrate is formed in the sealing end cover, the sealing end cover is fixedly arranged on the end face of the outer end part of the molded line partition plate hub, and the sealing device is axially fixed through the sealing end cover sleeved on the main shaft and the annular bulge on the main shaft.
The outer edge of the inner end surface of the molded line clapboard 11 is provided with a step surface which can be matched with the step surface at the mounting opening of the pump shell along the circumferential direction, the two step surfaces are clamped with sealing rings 111, and the pump shell 1 and the molded line clapboard 11 are fastened through corresponding bolts.
The main shaft 15 is vertically arranged, external threads are machined at the shaft head of the lower end of the main shaft 15, the shaft head of the main shaft sequentially penetrates through the impeller hub and the gasket of the impeller, the shaft head nut 20 is screwed on the rear of the impeller hub and the gasket of the impeller, the axial fixation of the impeller and the main shaft is realized through the shaft shoulder and the shaft head nut of the main shaft, the inner wall of the impeller hub is connected with the main shaft key, and the circumferential fixation of the impeller hub and the main shaft is realized.
The bottom end face of the upper cavity pump body 12 is provided with a bulge, the upper end face of the molded line partition board is provided with a clamping part which can be matched with the bulge, and the bulge and the clamping part are fastened through bolts.
The pump shell 1 is matched with the molded line partition plate 11 through a step surface, a sealing ring is additionally arranged on the step surface, so that fluid sealing is realized, and the molded line partition plate is fastened through bolts; the molded line baffle 11 is matched with the upper cavity pump body 12 through a bulge and a clamping part, and is fastened through bolts, and the upper part of the upper cavity pump body 12 is fixedly connected with the motor 13 through bolts, so that the connection and the fixation of the whole pump body are realized. The motor shaft of the motor 13 is connected with the coupler 14, the coupler 14 is fixedly connected with the main shaft 15 through an internal bolt, so that the coaxial rotation of the motor shaft and the main shaft 15 is realized, and compared with a bearing, the axial vibration amplitude of the main shaft 15 and the impeller 22 can be furthest reduced by adopting the connecting mode, so that the variation amplitude of the axial gap 2 is reduced, and the running stability of the pump is improved. The seal end cover 16 is fixed on the molded line baffle 11 through the bolt, encloses a space with the main shaft 15, molded line baffle 11 jointly, and sealing device 17 installs in this space, provides support and is fixed through the shaft shoulder of seal end cover 16, molded line baffle 11 and main shaft 15, and in the design of centrifugal pump shaft seal, the bearing seal type that commonly uses has: (1) sealing with filler; (2) mechanical sealing; (3) and (5) floating sealing. The requirements that one wishes to be able to achieve: (1) the sealing is safe and reliable; (2) the power consumption is low; (3) the method can adapt to the conversion states of different rotating speeds. The packing seal is a conventional gland seal. The packing is pressed by the gland to force the packing to be pressed on the sealing surface (the outer surface of the shaft and the sealing cavity) to generate radial force with sealing effect, thereby playing a role in sealing. The packing seal has simple structure, convenient operation and maintenance and low cost, and is divided into soft packing seal and hard packing seal according to the packing form adopted by the packing seal, and the soft packing seal and the hard packing seal are mainly used for machine equipment working at high pressure, high temperature and high speed. The soft packing seal has simple structure and easy replacement, and is quite common in application, so the packing seal is selected.
Referring to fig. 2 and fig. 4a to 4b, the backflow front cavity 4 is a streamline cavity formed by the impeller front cover plate 5 and the pump shell 1. In order to simulate the flowing state of fluid in the design of the invention, the design is subjected to fluid domain modeling and grid division, boundary layer segmentation is carried out at the fluid domain and the mouth ring between the pump cavity and the shell so as to ensure more accurate simulation results, meanwhile, the divided grids are subjected to convergence test, and the flow field is subjected to numerical calculation by the RNG k-epsilon model so as to obtain a flow diagram and a cloud diagram. According to the numerical simulation result, a very small part of the fluid flowing into the volute diffusion section through the impeller 22 flows into the backflow front cavity 4 through the gap 5, and the part of the fluid is lost, so that the efficiency of the pump is improved due to smaller backflow; the stable vortex exists in the backflow front cavity 4, because the streamline structure of the front cavity causes the fluid flowing into the front cavity from the impeller runner to flow back along the geometric structure of the front cavity, the rotation direction of the vortex is perpendicular to the gap 5 and the axial gap 2, which means that the fluid in the backflow front cavity 4 has little fluid interaction with other runners, the running stability is improved, the energy loss caused by dissipation is reduced, and the efficiency is improved. In addition, the annular gap 2 is an axial gap, and most centrifugal pumps are designed to be radial gaps, radial pressure pulsation of the centrifugal pump is difficult to avoid due to axial asymmetry of a volute and the existence of a partition tongue, so that the radial annular gap can be continuously changed when the pump is operated, and unstable fluid flow is caused.
With reference to fig. 2, 3 and 5, the impeller blades 7 are long blades, the length of which exceeds the length of the front cover plate and the rear cover plate, and reach one third of the average width of the volute diffusion section. Impeller blade is the main original paper of acting to the fluid, and the blade intensity of casting pump is limited, and the blade thickness of punching press welding pump is even, and intensity is high, can carry out the design and the manufacturing of long blade. An increase in the length of the vane means that the area where the vane does work on the fluid increases, which increases the pump head. According to the result of numerical simulation, the low-pressure area inside the impeller flow channel is few, and the low-pressure area of the planar structure has obvious pressure minimum area, which means that cavitation phenomenon is hardly generated in the impeller, and the stability and efficiency of the pump are improved. Meanwhile, most of fluid pumped by the impeller flows back to the impeller through the arc-shaped structure of the volute, and the fluid receives secondary work of the impeller, so that the lift is further improved.
With reference to fig. 2 and fig. 4 a-4 b, the linear rear cavity structure is a fluid domain formed by the linear partition plate 11 and the impeller rear cover plate 8, the linear rear cavity structure reduces the volume of the pump cavity to the maximum extent, and hydraulic design is performed through geometric data of the impeller rear cover plate, so that the linear rear cavity structure is more unified and standardized. The axial force of the centrifugal pump can cause considerable pressure on the sealing device and the main shaft, the service life and efficiency of the pump can be reduced due to leakage and vibration, and the result of numerical simulation shows that the back cavity flow channel of the linear structure is very small, the fluid speed is gradually decreased, the fluid speed at the inflection point is very small, the stable flowing state is still shown, the almost static fluid can balance the axial force to a certain extent, the effect of a balancing chamber is achieved, the pressure of the sealing device and the main shaft is reduced, the leakage is reduced, and the service life and efficiency of the centrifugal pump are prolonged. Meanwhile, the molded line partition plate 11 is also provided with a pressure relief hole 9, so that the liquid in the rear cavity can be cleaned and emptied.
The embodiments described in the present specification are merely examples of implementation forms of the inventive concept, and the scope of protection of the present invention should not be construed as being limited to the specific forms set forth in the embodiments, but also equivalent technical means that can be conceived by those skilled in the art according to the inventive concept.
Claims (3)
1. A high-lift long-blade molded line rear cavity structure centrifugal pump is characterized in that: the device comprises a pump shell, a volute, an impeller, a molded line partition board, an upper cavity pump body, a motor and a main shaft, wherein the pump shell is provided with a liquid inlet and a liquid outlet which can be communicated with an inner cavity of the pump shell; the volute and the pump shell are integrally formed, a first central hole and a second central hole are respectively formed in two sides of a spiral line segment of the volute, the first central hole is communicated with the liquid inlet through the liquid inlet flow channel, and the second central hole of the volute is communicated with the mounting opening at the upper end of the pump shell; the diffusion section of the volute is used as a liquid outlet flow channel to be communicated with a liquid outlet of the pump shell;
the impeller is arranged in a volute chamber of the volute, and is fixedly arranged on a shaft head of the main shaft extending into the volute chamber, the impeller comprises an impeller front cover plate, an impeller rear cover plate, an impeller hub and a plurality of blades, the blades are circumferentially arranged along the impeller hub, and the impeller front cover plate and the impeller rear cover plate are respectively arranged on the front side and the rear side of the blades and are connected with the blades; the central through hole of the impeller rear cover plate extends outwards along the axial direction of the central through hole to form an impeller hub; the impeller front cover plate and the inner wall of the pump shell at the same side form a circular backflow front cavity, and an axial gap and a circumferential gap are respectively reserved at the inner boundary and the outer boundary of the backflow front cavity, wherein the axial gap is a gap between the central suction inlet end face of the impeller front cover plate and the inner end face of the liquid inlet channel; the circumferential gap is a gap between the surface of the outer end part of the impeller front cover plate and the bulge of the inner wall of the volute;
the molded line baffle sealing cover is arranged at the mounting opening of the pump shell, a central through hole of the molded line baffle extends outwards along the axial direction to form a molded line baffle hub for mounting the main shaft, wherein the outer end part of the molded line baffle hub is connected with the main shaft in a sealing and rotating way, so that the main shaft rotates around the central shaft of the main shaft in the circumferential direction, the rest part of the molded line baffle hub is in clearance fit with the main shaft penetrating through the molded line baffle hub, and the main shaft clearance is an annular clearance; an arc-shaped gap which can be communicated with the annular gap is reserved between the inner end surface of the molded line partition plate and the impeller rear cover plate, and the arc-shaped gap is communicated with the annular gap to form a rear cavity structure of the centrifugal pump; the molded line partition board is provided with a pressure relief hole which can be communicated with the rear cavity structure;
the bottom of the upper cavity pump body is fixedly connected with the molded line partition board, the upper part of the upper cavity pump body is fixedly connected with a chassis of the motor, an output shaft of the motor extends into the upper cavity pump body, a shaft head of the output shaft is fixedly connected with the upper end of a main shaft through a coupler, the lower end of the main shaft penetrates through a central through hole of the molded line partition board and then extends into a volute chamber of a volute, an impeller is fixedly arranged on the shaft head of the main shaft, and the central shaft of the impeller is kept coincident with the central shaft of the main shaft;
the inner end surface of the molded line partition plate is parallel to the outer surface of the impeller back cover plate, namely the radian of the inner end surface is consistent with that of the impeller back cover plate, so that a uniform arc-shaped gap is reserved between the molded line partition plate and the impeller back cover plate; the length of the blades of the impeller exceeds the length of the front cover plate and the rear cover plate, and the distance between the front cover plate and the rear cover plate of the impeller and the separating tongue is one third of the length of the blades, so that the length of the blades is defined as the distance from the top ends of the blades to the center of the impeller;
the sealing device comprises a packing for sealing, a sealing element for blocking the leakage of the packing and a sealing end cover for limiting the axial movement of the main shaft, wherein the sealing element is sleeved at the outer end part of the annular gap, the packing for sealing is filled in a sealing cavity of the sealing element, and the packing is in direct contact with the outer wall of the main shaft; the sealing device is characterized in that an annular bulge for limiting the axial movement of the sealing element is arranged on the main shaft, a through hole for the main shaft to penetrate is formed in the sealing end cover, the sealing end cover is fixedly arranged on the end face of the outer end part of the molded line partition plate hub, and the sealing device is axially fixed through the sealing end cover sleeved on the main shaft and the annular bulge on the main shaft; the inner end surface of the molded line partition plate is provided with a step surface which can be matched with the step surface at the mounting opening of the pump shell along the circumferential direction of the inner end surface, sealing rings are clamped at the two step surfaces, and the pump shell and the molded line partition plate are fastened through corresponding bolts.
2. A high lift long vane molded line rear cavity structure centrifugal pump as defined in claim 1, wherein: the main shaft is vertically arranged, external threads are machined at the shaft head of the lower end of the main shaft, the shaft head of the main shaft sequentially penetrates through the impeller hub and the gasket of the impeller and then is screwed with the shaft head nut, the axial fixation of the impeller and the main shaft is realized through the shaft shoulder and the shaft head nut of the main shaft, the inner wall of the impeller hub is connected with the main shaft key, and the circumferential fixation of the impeller hub and the gasket is realized.
3. A high lift long vane molded line rear cavity structure centrifugal pump as defined in claim 2, wherein: the bottom end face of the upper cavity pump body is provided with a bulge, the upper end face of the molded line partition board is provided with a clamping part which can be matched with the bulge, and the bulge and the molded line partition board are fastened through bolts.
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| US10993601B2 (en) * | 2019-01-25 | 2021-05-04 | Haier Us Appliance Solutions, Inc. | Dishwashing appliances and pump assemblies |
| CN113662486B (en) * | 2020-05-13 | 2022-09-20 | 佛山市威灵洗涤电机制造有限公司 | Heating pump and dish washing machine |
| CN114352534A (en) * | 2021-12-21 | 2022-04-15 | 昆山奥兰克泵业制造有限公司 | Pump structure |
| CN114508510A (en) * | 2022-01-28 | 2022-05-17 | 浙江水泵总厂有限公司 | Liquid inlet structure of water pump |
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