Semi-open impeller multistage self-balancing pump

Abstract

The application relates to the technical field of fluid conveying mechanical equipment, and discloses a semi-open impeller multistage self-balancing pump which comprises a pump shaft, a front-mounted semi-open impeller and a reverse-mounted semi-open impeller, and an open wear-resistant flow channel is formed by the semi-open impellers and split wear-resistant lining plates and wear-resistant guide vanes. A middle carrier can be configured as an even-numbered middle carrier or an odd-numbered double-open middle carrier according to the total number of stages; in the even-numbered structure, the front-mounted semi-open impeller and the reverse-mounted semi-open impeller are equal in number of stages and are reversely arranged, medium is pressurized by the front-mounted impeller group, enters a high-pressure cavity and a liquid outlet cavity, then enters a transfer cavity of a tail section carrier through a middle body transition pipe, and then enters the reverse-mounted impeller group and flows back to the liquid outlet cavity and is output by a liquid outlet pipe; in the odd-numbered structure, a difference value axial thrust is jointly compensated by a first-stage impeller balance hole and a middle balance drum. The application can consider anti-blocking, wear resistance, low axial load and easy maintenance performance when conveying sand-containing, mud-containing or fine fiber-containing medium.

Description

Technical Field

[0001] This invention relates to the field of fluid transport machinery and equipment technology, specifically to a semi-open impeller multistage self-balancing pump, and more particularly to a semi-open impeller multistage pump that can form an axial force self-balancing structure according to the head requirements of even-numbered and odd-numbered stages, and is suitable for transporting sand-containing media. Background Technology

[0002] Multistage centrifugal pumps achieve high head output by using multiple impellers connected in series. They are commonly used in mine drainage, oilfield produced water transportation, chemical circulation, water treatment, and industrial booster systems. Traditional multistage centrifugal pumps mostly use closed impellers. The closed impeller is formed by a front cover plate, a rear cover plate, and blades to create a relatively closed flow channel, which can achieve high efficiency when conveying clean water or low-impurity media.

[0003] However, in harsh media containing sand, mud, crystalline particles, or fine fibers, closed impellers are prone to particle accumulation and fiber entanglement in their closed flow channels, impeller inlet rings, and interstage guide parts, leading to decreased pump efficiency, impeller blockage, or even rotor seizure. Semi-open impellers, due to the elimination of the front cover, have wider flow channels, making it less likely for particulate media to form closed accumulation dead zones, thus making them more suitable for conveying solid media.

[0004] However, when a semi-open impeller is used in a multi-stage pump, each impeller will generate a large axial thrust under the action of pressure difference. If the multi-stage impellers are all arranged in the same direction, the axial thrust will be superimposed at each stage, causing the pump shaft to have obvious axial movement, thereby aggravating the wear of bearings, mechanical seals, wear parts and wear rings.

[0005] Existing multistage self-balancing pumps typically use structures such as balance discs, balance drums, or balance pipes to compensate for axial forces. These structures rely on releasing the medium from the high-pressure side to the low-pressure side to generate balancing forces, resulting in continuous volume loss. In sandy media, the gaps between the balance disc, balance ring, and balance pipe are easily eroded and worn by high-speed particles, and the balancing effect decays over time.

[0006] Furthermore, in practical applications, enterprises have both even-numbered stage head requirements (e.g., four, six, eight stages) and odd-numbered stage head requirements (e.g., three, five, seven stages). A single even-numbered stage symmetrical structure is insufficient to cover odd-numbered stage products, while simply using traditional balancing discs or balancing pipes increases leakage losses and the number of vulnerable parts. Therefore, a self-balancing structure is needed that can separately protect even-numbered and odd-numbered stage semi-open impeller multistage pumps, ensuring that the product series has low axial load, anti-clogging and wear-resistant properties, and quick maintenance capabilities across different stage numbers. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a semi-open impeller multistage self-balancing pump, which solves the problems of existing closed impeller multistage pumps being prone to clogging in sandy media, traditional balancing structures suffering from leakage losses and wear, and ordinary semi-open multistage pumps having large axial thrust and being difficult to adapt to both single-stage and odd-stage products.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: a semi-open impeller multi-stage self-balancing pump, comprising a pump shaft, a positively mounted semi-open impeller and a reverse-mounted semi-open impeller sleeved on the pump shaft, a front-end support body for receiving the inlet liquid, a tail-end support body for medium transfer, a middle support body disposed between the positively mounted semi-open impeller and the reverse-mounted semi-open impeller, and wear-resistant liners and wear-resistant guide vanes respectively cooperating with the positively mounted semi-open impeller and the reverse-mounted semi-open impeller.

[0009] The positive-mounted semi-open impeller and the reverse-mounted semi-open impeller are arranged in opposite directions along the pump shaft axis, with the central support as the boundary. The central support is configured as an even-numbered stage central support or an odd-numbered double-open central support. When the total number of impeller stages is even, the positive-mounted semi-open impeller and the reverse-mounted semi-open impeller have the same number of stages and cancel each other out by opposite hydraulic axial thrust. When the total number of impeller stages is odd, the positive-mounted semi-open impeller and the reverse-mounted semi-open impeller differ by one stage, and the difference in axial thrust caused by the stage difference is compensated by the balance hole of the first stage impeller of the odd-numbered stage and the balance drum set in the double-open central support of the odd-numbered stage.

[0010] Preferably, the axial inlet side of the upright semi-open impeller forms an upright inlet, and the radial outer periphery forms an upright outlet; the upright wear-resistant liner is located on the open side of the upright semi-open impeller and is axially opposite to it, and the upright wear-resistant guide vane is arranged around the radial outer side of the upright semi-open impeller.

[0011] Preferably, the axial inlet side of the reverse-mounted semi-open impeller forms a reverse-mounted inlet, and the radial outer periphery forms a reverse-mounted outlet; the reverse-mounted wear-resistant liner is located on the open side of the reverse-mounted semi-open impeller and is axially opposite to it, and the reverse-mounted wear-resistant guide vane is arranged around the radial outer side of the reverse-mounted semi-open impeller.

[0012] Preferably, in the even-numbered stage structure, the middle carrier of the even-numbered stage is provided with a high-pressure chamber, a liquid outlet chamber, a middle bearing, and a liquid outlet pipe. The high-pressure chamber receives the medium output by the last stage positive wear-resistant guide vane. The liquid outlet chamber is connected to the transfer chamber of the tail section carrier through the middle body transition pipe, and receives the medium after being pressurized by the reverse impeller assembly and outputs it through the liquid outlet pipe.

[0013] Preferably, in the odd-stage structure, the first-stage positive-mounted semi-open impeller has odd-stage first-stage impeller balance holes, and the matching positive-mounted wear-resistant guide vanes have odd-stage first-stage wear-resistant guide vane balance holes; the odd-stage double-opening central bearing body is equipped with an internal fixed shaft, fixing bolts, a balance drum and a diaphragm. The balance drum is a static balance component, with its inner circle fixed to the internal fixed shaft and its outer circle fixed to the inside of the odd-stage double-opening central bearing body. An annular balance gap is formed between the balance drum and the diaphragm to adjust the pressure difference between the high and low pressure chambers in the middle through throttling and pressure relief and to produce an axial compensation effect.

[0014] Preferably, the front section of the carrier forms a liquid inlet chamber and is connected to a liquid inlet pipe, and the rear section of the carrier forms a transfer chamber and is connected to a middle transition pipe; the front section, the middle section, and the rear section of the carrier are all provided with limiting and fixing ears on their outer sides, and adjacent limiting and fixing ears are axially connected by a fastening sealing pipe.

[0015] Preferably, the positive wear-resistant liner, the negative wear-resistant liner, the positive wear-resistant guide vane, and the negative wear-resistant guide vane are all separate and detachable wear-resistant parts. After wear, they can be replaced individually or the dynamic and static fit clearance between the semi-open impeller and the wear-resistant liner can be finely adjusted by using axial shims, stop fits, and positioning parts.

[0016] This invention provides a semi-open impeller multi-stage self-balancing pump. It has the following beneficial effects:

[0017] 1. This invention unifies the even-stage self-balancing structure and the odd-stage self-balancing structure within the same semi-open impeller multistage pump system. The claims can simultaneously cover both even-stage and odd-stage products of the enterprise, avoiding insufficient product protection scope caused by protecting only a single even-stage structure.

[0018] 2. In the even-numbered stage structure, the present invention uses equal numbers and opposite directions of positively mounted semi-open impellers and reverse-mounted semi-open impellers to directly offset the axial thrust generated by the two sets of impellers on the pump shaft; at the same time, the even-numbered stage flow channel is organized according to the path of liquid inlet at the front, pressurization by the positively mounted impeller group, transition in the middle liquid outlet chamber, transfer at the tail, repressurization by the reverse-mounted impeller group and return to the liquid outlet chamber for output, which can correspond to the actual flow path in the enterprise's drawings.

[0019] 3. In the odd-stage structure, the present invention uses the first-stage impeller balance hole and the middle balance drum for combined compensation. First, the first-stage pressure relief is used to reduce the thrust of the upright impeller assembly, and then the annular end face of the balance drum is used to form a reverse compensation thrust, so that the odd-stage semi-open impeller multistage pump can also achieve low axial load operation.

[0020] 4. The present invention adopts semi-open impellers and is equipped with separate wear-resistant liners and wear-resistant guide vanes. The medium flow channel does not have the closed dead corners caused by the closed impeller front cover plate, which can be adapted to media containing sand, mud and fine fibers, and concentrates the main scouring and wear on the detachable wear-resistant parts.

[0021] 5. The present invention forms a modular axial clamping structure by limiting and fixing ears and fastening sealing tubes, so that the front bearing, middle bearing, tail bearing and internal wear-resistant parts are kept coaxially sealed and spliced, which is convenient for enterprises to assemble in different grades of modules and perform on-site maintenance. Attached Figure Description

[0022] Figure 1 This is a fully sectional assembly diagram of the even-stage semi-open impeller multi-stage self-balancing pump of the present invention.

[0023] Figure 2 This is a schematic diagram of the back-to-back arrangement structure of the forward-mounted semi-open impeller assembly and the reverse-mounted semi-open impeller assembly of the present invention.

[0024] Figure 3 This is a schematic diagram of the mating structure of the upright semi-open impeller, the upright wear-resistant liner, and the upright wear-resistant guide vane of the present invention.

[0025] Figure 4 This is a schematic diagram of the assembly structure of the reverse-mounted semi-open impeller, the reverse-mounted wear-resistant liner, and the reverse-mounted wear-resistant guide vane of the present invention.

[0026] Figure 5 This is a schematic diagram of the internal structure of the even-numbered middle support body of the present invention;

[0027] Figure 6 This is a fully sectional assembly diagram of the odd-stage semi-open impeller multi-stage self-balancing pump of the present invention.

[0028] Figure 7 This is a schematic diagram of the mating structure of the odd-numbered stage first-stage impeller balancing hole and the odd-numbered stage first-stage wear-resistant guide vane balancing hole of the present invention;

[0029] Figure 8 This is a schematic diagram of the structure of the odd-level double-opening central support body and the balancing drum assembly of the present invention;

[0030] Figure 9 This is a partial structural schematic diagram of the balancing drum, diaphragm, and annular balancing gap of the present invention;

[0031] Figure 10 This is a schematic diagram of the structure of the front support body, the liquid inlet chamber, and the liquid inlet pipe of the present invention;

[0032] Figure 11 This is a schematic diagram of the structure of the tail section carrier, the transfer cavity, and the middle transition tube of the present invention.

[0033] Among them, 1. Pump shaft; 2. Upright semi-open impeller; 201. Upright wear-resistant liner; 202. Upright inlet; 203. Upright wear-resistant guide vane; 204. Upright outlet; 3. Reverse semi-open impeller; 301. Reverse wear-resistant liner; 302. Reverse inlet; 303. Reverse wear-resistant guide vane; 304. Reverse outlet; 4. Even-numbered stage intermediate bearing; 401. High-pressure chamber; 402. Outlet chamber; 403. Intermediate bearing; 40 4. Discharge pipe; 5. Odd-numbered stage first-stage impeller balance hole; 501. Odd-numbered stage first-stage wear-resistant guide vane balance hole; 6. Odd-numbered stage double-opening middle support body; 601. Internal fixed shaft; 602. Fixing bolt; 603. Balance drum; 604. Diaphragm; 7. Front support body; 701. Inlet chamber; 702. Inlet pipe; 8. Tail support body; 801. Transfer chamber; 802. Middle transition pipe; 9. Limiting and fixing lug; 901. Fastening and sealing pipe. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see the appendix Figure 1 -Appendix Figure 11 This invention provides a semi-open impeller multi-stage self-balancing pump, comprising a pump shaft 1, a positively mounted semi-open impeller 2, a reverse-mounted semi-open impeller 3, a front support body 7, a rear support body 8, and a central support body disposed between the positively mounted semi-open impeller 2 and the reverse-mounted semi-open impeller 3. The pump shaft 1 is horizontally inserted along the axial direction of the entire machine. The positively mounted semi-open impeller 2 and the reverse-mounted semi-open impeller 3 are both coaxially fixedly mounted on the pump shaft 1 and rotate synchronously with the pump shaft 1 when the motor drives the pump shaft 1 to rotate.

[0036] The front-end carrier 7 is located on the liquid inlet side of the whole machine, and a liquid inlet chamber 701 is formed inside it. The liquid inlet chamber 701 is fixedly connected to the liquid inlet pipe 702. The liquid inlet pipe 702 is used to connect to the external liquid inlet pipeline. The liquid inlet chamber 701 is axially opposite to the liquid inlet 202 of the first-stage upright semi-open impeller 2, so that the medium can enter the liquid inlet chamber 701 through the liquid inlet pipe 702 and then directly enter the first-stage upright semi-open impeller 2.

[0037] The axial inlet side of the upright semi-open impeller 2 forms an upright inlet 202, and the radial outer periphery forms an upright outlet 204. The upright wear-resistant liner 201 is installed on the open side of the upright semi-open impeller 2, axially opposite to the blade end face of the upright semi-open impeller 2 and maintaining a preset dynamic and static fit clearance; the upright wear-resistant guide vane 203 is arranged around the radial outer side of the upright semi-open impeller 2, its inlet is connected to the upright outlet 204, and its outlet is connected to the upright inlet 202 of the adjacent next-stage upright semi-open impeller 2 or the central support body.

[0038] The reverse-mounted semi-open impeller 3 is installed in the opposite direction to the forward-mounted semi-open impeller 2, with a reverse-mounted inlet 302 formed on its axial inlet side and a reverse-mounted outlet 304 formed on its radial outer periphery. The reverse-mounted wear-resistant liner 301 is installed on the open side of the reverse-mounted semi-open impeller 3, axially opposite to the blade end face of the reverse-mounted semi-open impeller 3 and maintaining a preset dynamic and static fit clearance; the reverse-mounted wear-resistant guide vane 303 is arranged around the radial outer side of the reverse-mounted semi-open impeller 3, with its inlet connected to the reverse-mounted outlet 304 and its outlet connected to the outlet chamber 402 of the adjacent next-stage reverse-mounted semi-open impeller 3 or the middle support body 4 of the even-numbered stage.

[0039] The tail section carrier 8 is located on the axial outer side of the reverse-mounted semi-open impeller 3, and a transfer chamber 801 is formed inside it. The transfer chamber 801 is fixedly connected to the intermediate body transition pipe 802. The intermediate body transition pipe 802 is used to introduce the medium in the outlet chamber 402 of the even-numbered stage intermediate carrier 4 into the transfer chamber 801 of the tail section carrier 8. The transfer chamber 801 is then connected to the reverse-mounted inlet 302 of the first-stage reverse-mounted semi-open impeller 3, so that the medium enters the reverse-mounted impeller assembly from the tail section carrier 8.

[0040] In the even-stage embodiment, the middle support body is the even-stage middle support body 4. The even-stage middle support body 4 is located between the multi-stage forward-mounted semi-open impeller 2 and the multi-stage reverse-mounted semi-open impeller 3. The multi-stage forward-mounted semi-open impeller 2 is located on the side of the even-stage middle support body 4 near the front support body 7, and the multi-stage reverse-mounted semi-open impeller 3 is located on the side of the even-stage middle support body 4 near the rear support body 8.

[0041] The even-numbered stage intermediate support body 4 is equipped with a high-pressure chamber 401, a liquid outlet chamber 402, and an intermediate bearing 403, and is connected to a liquid outlet pipe 404. The high-pressure chamber 401 is connected to the outlet of the last stage positive-mounted wear-resistant guide vane 203 and is used to receive the medium after the positive-mounted impeller assembly has been pressurized in stages; the liquid outlet chamber 402 is connected to the high-pressure chamber 401 or receives the medium from the high-pressure chamber 401 through the intermediate flow channel, and the liquid outlet chamber 402 is connected to the intermediate transfer chamber 801 of the tail section support body 8 through the intermediate body transition pipe 802.

[0042] In the above-mentioned even-numbered flow path, the medium enters the intermediate transfer chamber 801 from the outlet chamber 402 through the intermediate body transition pipe 802. The medium in the intermediate transfer chamber 801 enters the reverse-mounted semi-open impeller 3 through the reverse-mounted inlet 302, and is then thrown out through the reverse-mounted outlet 304 and enters the reverse-mounted wear-resistant guide vane 303. After being pressurized step by step by the multi-stage reverse-mounted semi-open impeller 3, the medium finally returns to the outlet chamber 402 of the even-numbered stage middle carrier 4 and is output from the outlet pipe 404 connected to the outlet chamber 402.

[0043] The intermediate bearing 403 is coaxially supported in the middle of the pump shaft 1, and is used to reduce the deflection and vibration of the pump shaft 1 when the positive-mounted semi-open impeller 2 and the reverse-mounted semi-open impeller 3 are arranged in multiple stages. The discharge pipe 404 is fixedly connected to the discharge chamber 402, and is used to discharge the high-pressure medium from the whole machine after the reverse-mounted impeller group completes the secondary pressurization and returns the medium to the discharge chamber 402.

[0044] In the even-stage structure, the number of forward-mounted semi-open impellers 2 and reverse-mounted semi-open impellers 3 located on both sides of the middle support body 4 of the even-stage are the same, with the same impeller outer diameter and corresponding hydraulic flow channels. During operation, the forward-mounted semi-open impeller 2 generates a cumulative axial thrust towards the front support body 7 due to the pressure difference, while the reverse-mounted semi-open impeller 3 generates a cumulative axial thrust towards the rear support body 8 due to its reverse installation. The two sets of thrusts are opposite in direction on the pump shaft 1 and cancel each other out, thereby achieving self-balancing of the even-stage.

[0045] In the odd-stage embodiment, the central support body is an odd-stage double-open central support body 6. The number of stages of the upright semi-open impeller 2 is one more than that of the reverse semi-open impeller 3, or the number of stages of the reverse semi-open impeller 3 is one more than that of the upright semi-open impeller 2. The two form a difference in axial thrust on the pump shaft 1 caused by the difference in the number of stages. The following explanation uses the upright semi-open impeller 2 having one more stage as an example.

[0046] An odd number of first-stage impeller balance holes 5 are provided on the first-stage upright semi-open impeller 2 near the front support body 7. Correspondingly, an odd number of first-stage wear-resistant guide vane balance holes 501 are provided on the upright wear-resistant guide vane 203 that mates with the first-stage upright semi-open impeller 2. The odd number of first-stage impeller balance holes 5 and the odd number of first-stage wear-resistant guide vane balance holes 501 are connected axially and radially to form a first-stage pressure relief channel, which diverts the medium in the high-pressure area behind the first-stage upright semi-open impeller 2 to the low-pressure inlet side of the front support body 7, thereby reducing the axial thrust generated by the first-stage upright semi-open impeller 2.

[0047] An internal fixed shaft 601 is fixedly installed inside the odd-numbered double-opening central support body 6. The internal fixed shaft 601 is connected to the odd-numbered double-opening central support body 6 by fixing bolts 602 to form a fixed base for installing the static balancing component. The balancing drum 603 is a static balancing component and is located in the inner cavity of the odd-numbered double-opening central support body 6. Its inner circle side is fixed to the outer wall of the internal fixed shaft 601, and its outer circle side is fixed to the inner wall of the odd-numbered double-opening central support body 6. The pump shaft 1 passes through this central area and drives the positively mounted semi-open impeller 2 and the reversely mounted semi-open impeller 3 to rotate, but there is no transmission connection between the pump shaft 1 and the balancing drum 603, and the balancing drum 603 does not rotate with the pump shaft 1. The diaphragm 604 is arranged around the outer periphery of the balancing drum 603 and forms an annular balancing gap with the balancing drum 603.

[0048] One side of the annular balance gap connects to the high-pressure outlet side of the reverse-mounted semi-open impeller 3, and the other side connects to the low-pressure transition side between the upright semi-open impeller 2 and the reverse-mounted semi-open impeller 3. Since the inner side of the balance drum 603 is positioned by the internal fixed shaft 601, and the outer side is positioned by the odd-stage double-opening central support body 6, the high-pressure medium is throttled and depressurized through the annular balance gap defined by the balance drum 603 and the diaphragm 604, creating a stable pressure difference regulation between the high and low pressure chambers in the middle. This pressure difference regulation acts on the pump shaft 1 and the corresponding effective end faces of the upright semi-open impeller 2 and the reverse-mounted semi-open impeller 3, which are fixedly connected to the pump shaft 1, forming a compensating thrust towards the tail support body 8, which is opposite in direction to the axial thrust difference generated by the difference in stage number in the odd-stage structure. By designing the outer diameter of the balance drum 603, the inner diameter of the diaphragm 604, and the dimensions of the annular balance gap, the total axial force of the entire machine can be made close to zero.

[0049] Limiting and fixing ears 9 are provided on the outer sides of the front bearing 7, the middle bearing, and the tail bearing 8. Adjacent limiting and fixing ears 9 are axially connected by a fastening sealing tube 901. The fastening sealing tube 901 passes through or is clamped between adjacent limiting and fixing ears 9 along the axial direction of the pump shaft 1. An axial clamping force is applied by the end locking member to keep the front bearing 7, the middle bearing, the tail bearing 8, the positive wear-resistant liner 201, the positive wear-resistant guide vane 203, the reverse wear-resistant liner 301, and the reverse wear-resistant guide vane 303 coaxially sealed and spliced.

[0050] The positive wear-resistant liner 201, the negative wear-resistant liner 301, the positive wear-resistant guide vane 203, and the negative wear-resistant guide vane 303 are all detachable wear-resistant components. The positive wear-resistant liner 201 and the negative wear-resistant liner 301 respectively withstand the particle scouring from the open side of their respective semi-open impellers, while the positive wear-resistant guide vane 203 and the negative wear-resistant guide vane 303 respectively withstand the high-speed media scouring from the radial outlet side of their respective impellers. After wear, the corresponding wear-resistant liner or wear-resistant guide vane can be replaced individually, or the dynamic and static fit clearance between it and the corresponding semi-open impeller can be finely adjusted using shims, stop fits, and axial positioning components.

[0051] In this invention, neither the upright semi-open impeller 2 nor the reverse semi-open impeller 3 has a front cover plate. Mud and fine fibers in the medium can pass through the main flow channel, making it less likely for dead zones to form within the closed cover plate. The upright wear-resistant liner 201 and the reverse wear-resistant liner 301 serve as static wear-resistant covers on the open side of the semi-open impeller, concentrating the main wear on the detachable parts, thereby extending the service life of the pump shaft 1, the upright semi-open impeller 2, the reverse semi-open impeller 3, and each load-bearing component.

[0052] It should be noted that the even-stage structure of the present invention is applicable to four-stage, six-stage, eight-stage, or more even-stage pumps; the odd-stage structure of the present invention is applicable to three-stage, five-stage, seven-stage, or more odd-stage pumps. As long as the positively mounted semi-open impeller 2 and the reverse-mounted semi-open impeller 3 are arranged in opposite directions, and axial self-balancing is achieved through even-stage thrust counter-impact or odd-stage balance holes plus balance drums, they all fall within the protection scope of the present invention.

[0053] Working principle

[0054] When the even-numbered-stage semi-open impeller multistage self-balancing pump is running, the external motor drives the pump shaft 1 to rotate, and the pump shaft 1 drives the upright semi-open impeller 2 and the reverse semi-open impeller 3 to rotate synchronously. The medium enters the inlet chamber 701 of the front-end carrier 7 through the inlet pipe 702, and then enters the first-stage upright semi-open impeller 2 through the upright inlet port 202.

[0055] The medium is thrown out of the liquid outlet 204 by centrifugal force in the upright semi-open impeller 2, and then enters the upright wear-resistant guide vane 203 and is guided to the next stage upright semi-open impeller 2. After being pressurized by multiple stages of upright semi-open impeller 2, the medium enters the high-pressure chamber 401 of the even-numbered stage middle carrier 4, and then enters the liquid outlet chamber 402 from the high-pressure chamber 401.

[0056] Subsequently, the medium enters the transfer chamber 801 of the tail section carrier 8 through the intermediate transition pipe 802 from the outlet chamber 402. The medium in the transfer chamber 801 then enters the reverse-mounted semi-open impeller 3 through the reverse-mounted inlet 302, and is thrown out through the reverse-mounted outlet 304 under the action of centrifugal force within the reverse-mounted semi-open impeller 3. After being guided by the reverse-mounted wear-resistant guide vanes 303, the medium is pressurized and transported step by step along the reverse-mounted impeller assembly, and finally returns to the outlet chamber 402 of the even-numbered stage intermediate carrier 4, and is output under high pressure through the outlet pipe 404.

[0057] During the even-numbered stage operation described above, the axial thrust generated by the upright semi-open impeller 2 points towards the front bearing 7, while the axial thrust generated by the reverse semi-open impeller 3 points towards the rear bearing 8. Since the impellers on both sides have the same number of stages and corresponding hydraulic parameters, the two sets of axial thrust cancel each other out on the pump shaft 1, and the residual axial force is borne by the bearing assembly and the intermediate bearing 403.

[0058] When the odd-stage semi-open impeller multistage self-balancing pump is running, the number of stages of the upright semi-open impeller 2 and the reverse semi-open impeller 3 differs by one, thus generating a differential axial thrust. The odd-stage first-stage impeller balance hole 5 on the upright semi-open impeller 2 and the odd-stage first-stage wear-resistant guide vane balance hole 501 on the upright wear-resistant guide vane 203 form a first-stage pressure relief channel, allowing the medium in the high-pressure zone of the first stage to flow back to the low-pressure inlet side, thereby reducing the differential axial thrust in advance.

[0059] Meanwhile, the balance drum 603 inside the odd-numbered double-opening middle support body 6 remains stationary, with its inner circle fixed to the internal fixed shaft 601 and its outer circle fixed to the inner side of the odd-numbered double-opening middle support body 6. The medium from the high-pressure outlet side of the reverse-mounted semi-open impeller 3 enters the annular balance gap between the balance drum 603 and the diaphragm 604, and is throttled and depressurized through this annular balance gap, thereby adjusting the pressure difference between the high and low pressure chambers in the middle. This pressure difference acts on the pump shaft 1 and the corresponding effective end face of the impeller assembly it is fixed to, forming a compensating thrust toward the tail support body 8. This compensating thrust cancels out the remaining differential axial thrust, preventing the pump shaft 1 from experiencing significant axial movement.

[0060] Regardless of whether an even-stage or odd-stage structure is adopted, an open, adjustable dynamic and static fit clearance is formed between the upright wear-resistant liner 201 and the upright semi-open impeller 2, and between the reverse wear-resistant liner 301 and the reverse semi-open impeller 3. Sand-containing media are less prone to clogging when passing through this clearance. The erosion wear is mainly borne by the upright wear-resistant liner 201, the reverse wear-resistant liner 301, the upright wear-resistant guide vane 203, and the reverse wear-resistant guide vane 303. After wear, the wear-resistant parts can be replaced or the clearance adjusted by disassembling the connection at the fastening sealing pipe 901 and the limiting fixing ear 9.

[0061] Therefore, this invention enables the semi-open impeller multistage pump to be adapted to both even-stage and odd-stage products through two self-balancing paths: hydraulic counter-impellers in even-numbered stages and compensation with balance holes and balance drums in odd-numbered stages. At the same time, it maintains comprehensive performance such as anti-clogging, wear resistance, low axial load, and easy maintenance.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A semi-open impeller multistage self-balancing pump, comprising a pump shaft (1), a positively mounted semi-open impeller (2) and a reverse-mounted semi-open impeller (3) sleeved on the pump shaft (1), a front-end support body (7) for receiving the inlet liquid, a tail-end support body (8) for medium transfer, a middle support body disposed between the positively mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3), and wear-resistant liners and wear-resistant guide vanes respectively cooperating with the positively mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3); characterized in that, The positive-mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3) are arranged in opposite directions along the axial direction of the pump shaft (1) with the central support as the boundary. The central support is configured as an even-numbered-stage central support (4) or an odd-numbered-stage double-open central support (6). When the total number of impeller stages is even, the positive-mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3) have the same number of stages and cancel each other out by hydraulic axial thrust in opposite directions. When the total number of impeller stages is odd, the positive-mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3) differ by one stage, and the difference in axial thrust caused by the difference in stage is compensated by the balance hole (5) of the first stage impeller of the odd-numbered stage and the balance drum (603) set in the double-open central support (6) of the odd-numbered stage.

2. The semi-open impeller multi-stage self-balancing pump according to claim 1, characterized in that, The axial liquid inlet of the positive-mounted semi-open impeller (2) forms a positive-mounted liquid inlet (202), and the radial outer periphery of the positive-mounted semi-open impeller (2) forms a positive-mounted liquid outlet (204). The positive-mounted wear-resistant liner (201) is disposed on the open side of the positive-mounted semi-open impeller (2) and is axially opposite to it. The positive-mounted wear-resistant guide vane (203) surrounds the radial outer side of the positive-mounted semi-open impeller (2), and the inlet of the positive-mounted wear-resistant guide vane (203) is connected to the positive-mounted liquid outlet (204), and the outlet is connected to the adjacent next-stage positive-mounted semi-open impeller (2) or the central support body.

3. The semi-open impeller multi-stage self-balancing pump according to claim 2, characterized in that, The axial liquid inlet side of the reverse-mounted semi-open impeller (3) forms a reverse-mounted liquid inlet (302), and the radial outer periphery of the reverse-mounted semi-open impeller (3) forms a reverse-mounted liquid outlet (304). The reverse-mounted wear-resistant liner (301) is disposed on the open side of the reverse-mounted semi-open impeller (3) and is axially opposite to it. The reverse-mounted wear-resistant guide vane (303) surrounds the radial outer side of the reverse-mounted semi-open impeller (3), and the inlet of the reverse-mounted wear-resistant guide vane (303) is connected to the reverse-mounted liquid outlet (304), and the outlet is connected to the liquid outlet cavity (402) of the adjacent next-stage reverse-mounted semi-open impeller (3) or the middle support body (4) of the even-numbered stage.

4. The semi-open impeller multi-stage self-balancing pump according to claim 3, characterized in that, When the middle support body is an even-numbered middle support body (4), the even-numbered middle support body (4) is set between the positive-mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3) with the same number of stages. The even-numbered middle support body (4) is provided with a high-pressure chamber (401), a liquid outlet chamber (402) and a middle section bearing (403). The high-pressure chamber (401) is connected to the outlet of the last stage positive-mounted wear-resistant guide vane (203). The liquid outlet chamber (402) is connected to the middle body transition pipe (802), the outlet of the last stage reverse-mounted wear-resistant guide vane (303) and the liquid outlet pipe (404) respectively. The middle section bearing (403) is coaxially supported in the middle of the pump shaft (1).

5. The semi-open impeller multi-stage self-balancing pump according to claim 4, characterized in that, In the even-numbered stage structure, the liquid outlet chamber (402) is connected to the transfer chamber (801) of the tail section carrier (8) through the middle body transition pipe (802). The transfer chamber (801) is connected to the reverse inlet (302) of the first-stage reverse-mounted semi-open impeller (3). The reverse-mounted semi-open impeller (3) is transported step by step through the reverse-mounted liquid outlet (304) and the reverse-mounted wear-resistant guide vane (303) and then flows back to the liquid outlet chamber (402) and is output by the liquid outlet pipe (404).

6. The semi-open impeller multi-stage self-balancing pump according to claim 3, characterized in that, When the middle carrier is an odd-stage double-opening middle carrier (6), the first-stage positive-mounted semi-open impeller (2) near the front carrier (7) is provided with the odd-stage first-stage impeller balance hole (5), and the positive-mounted wear-resistant guide vane (203) that cooperates with the first-stage positive-mounted semi-open impeller (2) is provided with the odd-stage first-stage wear-resistant guide vane balance hole (501). The odd-stage first-stage impeller balance hole (5) and the odd-stage first-stage wear-resistant guide vane balance hole (501) are connected to guide the medium in the high-pressure area behind the first-stage positive-mounted semi-open impeller (2) to the low-pressure liquid inlet side of the front carrier (7).

7. The semi-open impeller multi-stage self-balancing pump according to claim 6, characterized in that, An internal fixed shaft (601) is fixedly installed inside the odd-numbered double-opening central support body (6). The internal fixed shaft (601) is connected to the odd-numbered double-opening central support body (6) by a fixing bolt (602). The balance drum (603) is a static balancing component and is fixedly installed in the inner cavity of the odd-numbered double-opening central support body (6). The inner circle side of the balance drum (603) is fixedly connected to the outer wall of the internal fixed shaft (601). The outer circle side of the balance drum (603) is fixedly connected to the inner side wall of the odd-numbered double-opening central support body (6). The diaphragm (604) is arranged around the outer circumference of the balance drum (603) and forms an annular balance gap with the balance drum (603). The pump shaft (1) and the balance drum (603) do not form a synchronous rotational connection.

8. The semi-open impeller multi-stage self-balancing pump according to claim 7, characterized in that, One side of the annular balance gap is connected to the high-pressure liquid outlet side of the reverse-mounted semi-open impeller (3), and the other side is connected to the low-pressure transition side between the upright semi-open impeller (2) and the reverse-mounted semi-open impeller (3). The pressure difference between the high and low pressure chambers in the middle is adjusted through the throttling and pressure relief channel defined by the balance drum (603) and the diaphragm (604). A compensating thrust opposite to the direction of the differential axial thrust in the odd-stage structure is formed on the pump shaft (1) and the upright semi-open impeller (2) and the reverse semi-open impeller (3) which are fixedly connected to the pump shaft (1).

9. The semi-open impeller multi-stage self-balancing pump according to claim 8, characterized in that, The front section carrier (7) forms an inlet chamber (701) inside, which is connected to the inlet pipe (702) and is axially opposite to the first-stage positive inlet (202); the tail section carrier (8) forms a transfer chamber (801) inside, which is connected to the middle body transition pipe (802) and is connected to the first-stage reverse inlet (302).

10. The semi-open impeller multistage self-balancing pump according to claim 9, characterized in that, The front section carrier (7), the middle section carrier and the tail section carrier (8) are all provided with limiting fixing ears (9) on their outer sides. Adjacent limiting fixing ears (9) are axially connected by fastening sealing tubes (901). The positive-mounted semi-open impeller (2) and the reverse-mounted semi-open impeller (3) are both coaxially fixedly connected to the pump shaft (1) and rotate synchronously with the pump shaft (1). The positive-mounted wear-resistant liner (201) and the reverse-mounted wear-resistant liner (301) remain stationary relative to the corresponding semi-open impeller. An adjustable dynamic and static fit clearance is formed between the positive-mounted wear-resistant liner (201) and the positive-mounted semi-open impeller (2), and between the reverse-mounted wear-resistant liner (301) and the reverse-mounted semi-open impeller (3).

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