A mixed flow pump with a sewage pretreatment device

Abstract

The application discloses a mixed-flow pump with a sewage pretreatment device, which belongs to the technical field of mixed-flow pumps and comprises a base, a water outlet pipe and a water inlet pipe. A motor and a pump body are fixedly installed on the top of the base. The output shaft of the motor is in transmission connection with the transmission shaft of the pump body through a shaft coupling. A filter assembly is fixedly installed on the left side of the pump body. A mounting cover and bolts are arranged on the left side of the filter assembly. A filter cartridge is press-fitted on the inner wall of the filter assembly through the mounting cover, the bolts and a fixing ring. The filter plate is driven to move rightward and rotate synchronously, so that the second spring is driven to stretch. The third filter hole is arranged to allow large-particle impurities to enter the "dynamic filtering area". When the number of the large-particle impurities entering increases, the filter plate is pushed leftward. The large-particle impurities in the "dynamic filtering area" are driven to rotate through the cooperation of the filter plate and the rotating strip, so that the probability of being squeezed in the water channel is reduced, and the sewage passing efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mixed flow pumps, in particular to a mixed flow pump with a sewage pretreatment device. BACKGROUND

[0002] A mixed flow pump is a water conservancy machinery between a centrifugal pump and an axial flow pump, which uses the axial thrust generated by the rotation of the impeller to transfer and impart high pressure to the water to complete the conveying work. The mixed flow pump generally sets a sewage pretreatment device when transferring sewage, which filters large particle impurities in the sewage to improve the stability of the microbial environment in the water body during subsequent treatment, and provides stable conditions for subsequent biochemical precipitation. Therefore, the mixed flow pump for sewage transfer and conveying generally has a sewage pretreatment function.

[0003] At present, the mixed flow pump with a sewage pretreatment device in the prior art generally sets a sewage pretreatment assembly at the water inlet end of the pump body. The common treatment method is to filter large particle impurities in the sewage to improve the water quality of the sewage. The filtering method is mostly multi-layer filter screen filtering. In the working process, the surface of the filter screen will be crowded (not blocked) by the gradually accumulated impurities over time. These crowding phenomena will cause the water flow passage to become narrow. Since there is a lack of dynamic adjustment measures, the transportation efficiency of the sewage will decrease. At the same time, the narrow water channel will retain more small particle impurities, increasing the working burden of the entire filter assembly, and eventually causing serious blockage.

[0004] Therefore, it is necessary to design a filter assembly that can be automatically and dynamically adjusted. The purpose of the design of the present application is to improve the sewage pretreatment capacity of the mixed flow pump. SUMMARY

[0005] The present application aims to provide a mixed flow pump with a sewage pretreatment device to solve the problems of low sewage passing efficiency and poor filtering effect in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a mixed-flow pump with a sewage pretreatment device, comprising a base, an outlet pipe, and an inlet pipe. A motor and a pump body are fixedly mounted on the top of the base. The output shaft of the motor is connected to the drive shaft of the pump body via a coupling. A filter assembly is fixedly mounted on the left side of the pump body. A mounting cover and bolts are provided on the left side of the filter assembly. A filter cylinder is press-fitted onto the inner wall of the filter assembly using the mounting cover, bolts, and a retaining ring. A first filter hole and a second filter hole are respectively opened on the surface of the filter cylinder. The inner wall of the filter cylinder is fixed... A rotating bar is connected to the filter cylinder, and a filter plate is rotatably mounted on the inner wall of the filter cylinder via the rotating bar. The filter plate has a third filter hole on its left side, and the cross-sectional shape of the third filter hole is an isosceles trapezoid with the left side higher than the right side. A placement groove is provided on the right side of the filter plate. Two locking blocks are movably engaged inside the placement groove, and a connecting cylinder is movably connected to the locking blocks. The other end of the connecting cylinder extends through to the right side of the filter cylinder. A connecting column and a first spring are movably fitted inside the filter cylinder. A connecting plate is fixedly connected to the other end of the connecting column, and a second spring is provided between the connecting plate and the filter cylinder.

[0007] As a further embodiment of the present invention, the inlet pipe is fixedly installed on the left side of the mounting cover, the outlet pipe is fixedly installed on the front side of the pump body, the fixing ring is fixedly connected to the left side of the inner wall of the filter assembly, and the outer edge of the filter cylinder is pressed into contact with the fixing ring.

[0008] As a further embodiment of the present invention, a rotating plate is fixedly connected to the left side of the filter plate, and there are four rotating plates distributed at equal angles on the surface of the filter plate. The filter plate and the third filter hole are arranged in an alternating pattern.

[0009] As a further embodiment of the present invention, the rotating bar is spirally distributed on the inner wall of the filter cylinder, the filter cylinder has two spiral turns, and the filter plate is adapted to engage with the outer surface of the rotating bar.

[0010] As a further embodiment of the present invention, the cross-sectional shape of the card block is "T" shaped, the card block is rotated and engaged inside the placement groove, and the end of the connecting cylinder connected to the card block is in limiting contact with the right side of the filter plate.

[0011] As a further embodiment of the present invention, the first spring and the connecting post are sequentially sleeved inside the connecting cylinder from left to right. The connecting post is elastically supported inside the connecting cylinder by the first spring. The right end of the connecting cylinder is in contact with the connecting plate. The two ends of the second spring are elastically connected to the filter cylinder and the connecting plate, respectively.

[0012] As a further embodiment of the present invention, the first filter hole is formed on the outer surface of the filter cylinder, the second filter hole is formed on the right side of the filter cylinder, and the diameter of the second filter hole is greater than the diameter of the first filter hole.

[0013] As a further embodiment of the present invention, the first spring is compressed and disposed inside the connecting cylinder by the connecting column, and the second spring is in a stretched state under initial conditions.

[0014] As a further embodiment of the present invention, the diameter of the narrowest part of the third filter hole is greater than the diameter of the second filter hole.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. This invention creates a "dynamic filtration zone" by setting up a filter plate that continuously moves and rotates to the right along the outer surface of a rotating bar under the pressure of sewage. When sewage enters the interior of the filter cylinder and applies pressure to the filter plate, it drives the filter plate to move to the right and rotate synchronously, causing the second spring to be stretched. Large particles of impurities are allowed to enter the "dynamic filtration zone" through the third filter hole. As the number of large particles of impurities increases, they begin to push the filter plate to the left. Through the cooperation of the filter plate and the rotating bar, the large particles of impurities in the "dynamic filtration zone" rotate, reducing the probability of squeezing the water channel and improving the sewage passage efficiency.

[0017] 2. Then, by setting up a rotating plate connected to the filter plate, the rotating plate is driven to rotate when the filter plate rotates, which increases the kinetic energy of small particulate impurities in the sewage, thereby increasing the moving speed and avoiding clogging of the second filter hole. In addition, the rotating filter plate synchronously scrapes the inner wall of the filter cylinder, which helps to remove clogging impurities near the first filter hole, reduces the probability of the device clogging, and improves the pretreatment capacity of the device.

[0018] 3. Finally, the filter cartridge is pressed together using a mounting cover and bolts. When the filter cartridge needs maintenance, simply remove the bolts to disassemble it. By pulling the filter plate outwards, the connecting cylinder moves, stretching the first spring and creating a cleaning gap between the filter plate and the filter cartridge. This allows large particles of impurities filtered inside the filter cartridge to be removed, making cleaning efficient and labor-saving. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 This is a top view of the overall structure of the present invention;

[0021] Figure 3 This is a partial cross-sectional view of the overall structure of the present invention from the front.

[0022] Figure 4 For the present invention Figure 3 Enlarged schematic diagram of the structure at point A;

[0023] Figure 5 This is a top-view partial sectional view of the overall structure of the present invention;

[0024] Figure 6 For the present invention Figure 5 Enlarged schematic diagram of the structure at point B;

[0025] Figure 7 For the present invention Figure 5 Enlarged schematic diagram of the structure at point C;

[0026] Figure 8 This is a schematic diagram showing the separation of the filter assembly, mounting cover, bolts, water inlet pipe, fixing element, filter cylinder, rotating bar, filter plate, locking block, rotating plate, connecting cylinder, and spring No. 2 of the present invention.

[0027] Figure 9 This is a schematic diagram showing the separation of the filter plate, the locking block, the rotating plate, the connecting cylinder, the connecting column, the first spring, the connecting plate, and the second spring of the present invention.

[0028] The attached diagram lists the components represented by each number as follows:

[0029] 1. Base; 2. Motor; 3. Coupling; 4. Pump body; 5. Outlet pipe; 6. Filter assembly; 7. Mounting cover; 8. Bolt; 9. Inlet pipe; 10. Fixing ring; 11. Filter cylinder; 12. Filter hole No. 1; 13. Filter hole No. 2; 14. Rotating bar; 15. Filter plate; 16. Locking block; 17. Filter hole No. 3; 18. Placement slot; 19. Rotating plate; 20. Connecting cylinder; 21. Connecting column; 22. Spring No. 1; 23. Connecting plate; 24. Spring No. 2. Detailed Implementation

[0030] Please see Figures 1-9This invention provides a technical solution: a mixed-flow pump with a sewage pretreatment device, including a base 1, an outlet pipe 5, and an inlet pipe 9. A motor 2 and a pump body 4 are fixedly mounted on the top of the base 1. The output shaft of the motor 2 is connected to the drive shaft of the pump body 4 via a coupling 3. A filter assembly 6 is fixedly mounted on the left side of the pump body 4. A mounting cover 7 and bolts 8 are provided on the left side of the filter assembly 6. A filter cylinder 11 is press-fitted onto the inner wall of the filter assembly 6 via the mounting cover 7, bolts 8, and a fixing ring 10. A first filter hole 12 and a second filter hole 13 are respectively opened on the surface of the filter cylinder 11. A rotating strip 14 is fixedly connected to the inner wall of the filter cylinder 11. A filter plate 15 is rotatably mounted on the inner wall of the filter cylinder 11 via a rotating bar 14. A third filter hole 17 is provided on the left side of the filter plate 15. The cross-sectional shape of the third filter hole 17 is an isosceles trapezoid with the left side higher than the right side. A placement groove 18 is provided on the right side of the filter plate 15. Two locking blocks 16 are movably engaged inside the placement groove 18, and a connecting cylinder 20 is movably connected through the locking blocks 16. The other end of the connecting cylinder 20 extends through to the right side of the filter cylinder 11. A connecting post 21 and a first spring 22 are movably sleeved inside the filter cylinder 11. A connecting plate 23 is fixedly connected to the other end of the connecting post 21. A second spring 24 is provided between the connecting plate 23 and the filter cylinder 11.

[0031] During installation, the filter cylinder 11 is pressed into contact with the fixing ring 10, and then the mounting cover 7 is pressed onto the left side of the filter assembly 6 and installed by bolts 8. When sewage from the inlet pipe 9 enters the interior of the filter assembly 6, it fills the interior of the pump body 4 and is then discharged under high pressure along the outlet pipe 5. At this time, the filter plate 15 is subjected to water pressure and moves to the right. Through the limit of the rotating bar 14, the connecting cylinder 20 and the connecting plate 23 are driven to move to the right, and the second spring 24 is continuously stretched until the internal space of the filter cylinder 11 is compressed to the minimum by the filter plate 15.

[0032] Then, large particles of impurities enter the interior of the filter cylinder 11 along the block 16. As the water pressure continues to act to the right on the filter plate 15, the friction between the rotating bar 14 and the filter plate 15 counteracts the rebound force of the second spring 24. Large particles of impurities accumulate more and more in the "dynamic filtration area" formed between the inner cavity of the filter cylinder 11 and the filter plate 15. The right side of the filter plate 15 is gradually pushed to the left by the increasing large particles of impurities and gradually moves to the left. The rotating bar 14 makes the filter plate 15 rotate synchronously, which drives the large particles of impurities on both sides of the filter plate 15 to rotate, thereby reducing the degree of congestion.

[0033] As the space of the "dynamic filtration zone" becomes larger, the sewage, after pre-treatment by filtration, flows to the right along the first filter hole 12 and the second filter hole 13 respectively. Under the action of the pump body 4, it is discharged under high pressure. When the filter plate 15 rotates, it drives the rotating plate 19 to rotate and stirs the water flow inside the filter cylinder 11, increasing the kinetic energy of small particles in the sewage. As the filter plate 15 rotates while moving, it scrapes the inner wall of the filter cylinder 11, removing any possible blockages. The stirred sewage also drives the large particles remaining in the "dynamic filtration zone" to rotate, clearing any possible blockages near the second filter hole 13.

[0034] During cleaning, remove bolt 8, take off the mounting cover 7, and then take the filter cylinder 11 out of the filter assembly 6 as a whole. Pull the filter plate 15 to the left and move the connecting cylinder 20 so that the connecting cylinder 20 is separated from the outer surface of the connecting column 21. The first spring 22 is stretched. At this time, the staff can clean the large particles of impurities filtered on the inner wall of the filter cylinder 11 to achieve the function of regular maintenance. After the cleaning is completed, the filter cylinder 11 can be installed back in its original position.

[0035] This invention employs a pretreatment process for wastewater by using a press-fitted filter cylinder 11 to filter large particles. A rotating bar 14 and a filter plate 15 are included. When wastewater enters the filter cylinder 11 and applies pressure to the filter plate 15, it moves the filter plate 15 to the right and rotates synchronously. This stretches the second spring 24, allowing large particles to enter the "dynamic filtration zone" through the third filter hole 17. As the number of large particles increases, they begin to push against the filter plate 15 to the left, disrupting its dynamic balance and causing it to move and rotate. During this rotation, the large particles within the "dynamic filtration zone" are moved, reducing the probability of congestion and improving wastewater throughput.

[0036] Meanwhile, the filter plate 15, which is pushed to the left and moves, rotates under the action of the rotating bar 14. The rotating plate 19 agitates the sewage inside the filter cylinder 11, increasing the kinetic energy of small particulate impurities in the sewage and increasing their movement speed. This prevents clogging of the second filter hole 13. At the same time, during the rotation and movement of the filter plate 15, the outer surface of the filter plate 15 scrapes against the inner wall of the filter cylinder 11, removing small particulate impurities stuck inside the first filter hole 12, reducing the probability of clogging and improving the pretreatment capacity of the device.

[0037] Finally, the filter cylinder 11 is pressed together by the mounting cover 7 and bolts 8. When the filter cylinder 11 needs maintenance, the bolts 8 are removed to disassemble the filter cylinder 11. The filter plate 15 is pulled outwards from the filter cylinder 11, which moves the connecting cylinder 20 and stretches the first spring 22, forming a cleaning gap between the filter plate 15 and the filter cylinder 11. This cleans the large particles of impurities filtered inside the filter cylinder 11, making cleaning efficient and labor-saving.

[0038] Among them, the inlet pipe 9 is fixedly installed on the left side of the mounting cover 7, the outlet pipe 5 is fixedly installed on the front of the pump body 4, the fixing ring 10 is fixedly connected to the left side of the inner wall of the filter assembly 6, and the outer edge of the filter cylinder 11 is pressed and contacted with the fixing ring 10.

[0039] Wastewater enters the filter assembly 6 and filter cartridge 11 through the inlet pipe 9. After double-layer filtration by the filter plate 15 and filter cartridge 11, the pre-treated wastewater enters the pump body 4 and is discharged under high pressure through the outlet pipe 5. Figure 3 As shown, the left side of the outer edge of the filter cylinder 11 is in contact with the mounting cover 7, and the right side of the outer edge of the filter cylinder 11 is in contact with the fixing ring 10. Under the action of the bolt 8, the filter cylinder 11 can be fixed inside the filter assembly 6, and a sealing function can also be achieved.

[0040] Among them, a rotating plate 19 is fixedly connected to the left side of the filter plate 15. There are four rotating plates 19, which are distributed at equal angles on the surface of the filter plate 15. The filter plate 15 and the third filter hole 17 are arranged in an alternating manner.

[0041] The rotating plate 19 is driven by the rotating filter plate 15 to agitate the sewage inside the filter cylinder 11, which can move small particulate impurities in the sewage and increase their kinetic energy, thus avoiding clogging that may occur when moving in a low kinetic energy state.

[0042] The rotating bar 14 is spirally distributed on the inner wall of the filter cylinder 11, the filter cylinder 11 has two spiral turns, and the filter plate 15 is adapted to be engaged with the outer surface of the rotating bar 14.

[0043] The spirally distributed rotating strips 14 are adapted and engaged with the filter plate 15, so that when the filter plate 15 is moved by an external force, it can rotate along the outer surface of the rotating strips 14. During the rotation of the filter plate 15, large particles of impurities in the "dynamic filtration area" can be moved, reducing the degree of blockage in the waterway, thereby assisting the sewage to pass through more efficiently. At the same time, it can also drive the rotating plate 19 to rotate.

[0044] The cross-sectional shape of the locking block 16 is "T" shaped. The locking block 16 is rotated and locked inside the placement groove 18. The end of the connecting cylinder 20 connected to the locking block 16 is in limiting contact with the right side of the filter plate 15.

[0045] The T-shaped locking blocks 16 are used to connect the connecting cylinder 20 and the filter plate 15. The filter plate 15 needs to rotate when it moves. Therefore, the locking blocks 16 can rotate freely along the inside of the placement groove 18 to ensure that the rotation of the filter plate 15 is not jammed, and also to allow the filter plate 15 to drive the connecting cylinder 20 to move.

[0046] Among them, the first spring 22 and the connecting column 21 are sequentially sleeved inside the connecting cylinder 20 from left to right. The connecting column 21 is elastically supported inside the connecting cylinder 20 by the first spring 22. The right end of the connecting cylinder 20 is pressed and contacted with the connecting plate 23. The two ends of the second spring 24 are elastically connected to the filter cylinder 11 and the connecting plate 23 respectively.

[0047] The connecting column 21 and the first spring 22 are used to connect the connecting cylinder 20 and the connecting plate 23. Under normal working conditions, the connecting cylinder 20 and the connecting plate 23 are in a state of compression contact. Even if the connecting cylinder 20 moves to the left, the degree of compression is reduced. Therefore, in conjunction with the second spring 24 and the connecting plate 23, the first spring 22 can continuously apply pressure to the filter plate 15 to the left, ensuring that the filter plate 15 can rotate and filter.

[0048] Among them, the first filter hole 12 is opened on the outer surface of the filter cylinder 11, and the second filter hole 13 is opened on the right side of the filter cylinder 11. The diameter of the second filter hole 13 is larger than the diameter of the first filter hole 12.

[0049] The No. 1 filter hole 12 and the No. 2 filter hole 13 are used to allow sewage to pass through and filter small particulate impurities. Since the outer surface of the filter plate 15 cleans the area near the No. 1 filter hole 12 when it rotates, the clogging pressure of the No. 1 filter hole 12 is less than that of the No. 2 filter hole 13. However, large particulate impurities driven by water pressure may temporarily clog the No. 2 filter hole 13 at a certain position during rotation, which is fatal. It is necessary to appropriately increase the diameter of the No. 2 filter hole 13 to solve this potential problem.

[0050] Among them, the first spring 22 is compressed and installed inside the connecting cylinder 20 by the connecting column 21, and the second spring 24 is in a stretched state under the initial conditions;

[0051] Spring 22 and connecting post 21 are used to connect connecting cylinder 20 and connecting plate 23. Under normal working conditions, connecting plate 23 and spring 24 are always in contact. During cleaning, filter plate 15 can be pulled to the outside of filter cylinder 11. The reset pressure is obtained by stretching spring 22. There is a gap available when cleaning the inside of filter cylinder 11. After cleaning, it can assist in reset.

[0052] Among them, the diameter of the narrowest part of filter hole 17 is greater than the diameter of filter hole 13.

[0053] The left-wide and right-narrow design of the No. 3 filter hole 17 is mainly to prevent large particles of impurities in the "dynamic filtration area" from flowing back through the No. 3 filter hole 17. The diameter of the No. 3 filter hole 17 is larger than that of the No. 2 filter hole 13 to prevent large particles of impurities from flowing into the pump body 4.

[0054] Working principle:

[0055] First, install the filter cylinder 11 inside the filter assembly 6 and fix it with the mounting cover 7 and bolts 8. Connect the inlet pipe 9 to the sewage source, start the motor 2 and drive the pump body 4 to run, so that the sewage enters the filter assembly 6 and the pump body 4 and is discharged along the outlet pipe 5. The sewage pushes the filter plate 15 to the right and makes the filter plate 15 rotate, which drives the connecting cylinder 20 and the connecting plate 23 to move to the right and stretch the second spring 24.

[0056] Then, large particles of impurities in the wastewater enter the "dynamic filtration zone" through the third filter hole 17. They gradually increase and push the filter plate 15 to the left, causing the filter plate 15 to rotate as it moves. This causes the large particles of impurities in the "dynamic filtration zone" to rotate and simultaneously scrape the inner wall of the filter cylinder 11 to remove blockages. At the same time, the filter plate 15 drives the rotating plate 19 to rotate, stirring the water flow inside the filter cylinder 11 and increasing the kinetic energy of the small particles of impurities in the wastewater. The filtered wastewater enters the right side of the inner wall of the filter assembly 6 and is then driven by the high-speed rotating impeller inside the pump body 4 to be discharged along the outlet pipe 5.

[0057] Finally, remove bolt 8, take off the mounting cover 7, and then take the filter cylinder 11 out of the filter assembly 6 as a whole. Pull the filter plate 15 to the left and move the connecting cylinder 20 so that the connecting cylinder 20 is separated from the outer surface of the connecting column 21. The first spring 22 is stretched. At this time, the staff can clean the large particles of impurities filtered on the inner wall of the filter cylinder 11 to achieve the function of regular maintenance. After the work is completed, the filter cylinder 11 can be installed back in its original position.

Claims

1. A mixed-flow pump with a sewage pretreatment device, comprising a base (1), an outlet pipe (5), and an inlet pipe (9), wherein a motor (2) and a pump body (4) are fixedly mounted on the top of the base (1), the output shaft of the motor (2) is connected to the drive shaft of the pump body (4) via a coupling (3), and a filter assembly (6) is fixedly mounted on the left side of the pump body (4), characterized in that: The filter assembly (6) is provided with a mounting cover (7) and bolts (8) on the left side. The filter cylinder (11) is installed on the inner wall of the filter assembly (6) by pressing together the mounting cover (7), bolts (8) and fixing ring (10). The surface of the filter cylinder (11) is provided with a first filter hole (12) and a second filter hole (13). A rotating bar (14) is fixedly connected to the inner wall of the filter cylinder (11). The filter plate (15) is rotatably installed on the inner wall of the filter cylinder (11) by rotating the rotating bar (14). A third filter hole (17) is provided on the left side of the filter plate (15). The cross-sectional shape of the third filter hole (17) is an isosceles trapezoid with the left side higher than the right side. A release hole is provided on the right side of the filter plate (15). The placement groove (18) has two movable locking blocks (16) inside and a connecting cylinder (20) is movably connected through the locking blocks (16). The other end of the connecting cylinder (20) extends to the right side of the filter cylinder (11). The filter cylinder (11) is movably fitted with a connecting column (21) and a first spring (22). The other end of the connecting column (21) is fixedly connected to a connecting plate (23). A second spring (24) is provided between the connecting plate (23) and the filter cylinder (11). The rotating bar (14) is spirally distributed on the inner wall of the filter cylinder (11). The number of spiral turns of the filter cylinder (11) is two. The filter plate (15) is adapted to be locked on the outer surface of the rotating bar (14).

2. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: The inlet pipe (9) is fixedly installed on the left side of the mounting cover (7), the outlet pipe (5) is fixedly installed on the front of the pump body (4), the fixing ring (10) is fixedly connected to the left side of the inner wall of the filter assembly (6), and the outer edge of the filter cylinder (11) is pressed against the fixing ring (10).

3. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: A rotating plate (19) is fixedly connected to the left side of the filter plate (15). There are four rotating plates (19) and they are distributed at equal angles on the surface of the filter plate (15). The filter plate (15) and the third filter hole (17) are arranged in an alternating pattern.

4. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: The cross-sectional shape of the card block (16) is "T" shaped. The card block (16) is rotated and engaged inside the placement groove (18). The end of the connecting cylinder (20) connected to the card block (16) is in limiting contact with the right side of the filter plate (15).

5. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: The first spring (22) and the connecting column (21) are sequentially sleeved inside the connecting cylinder (20) from left to right. The connecting column (21) is elastically supported inside the connecting cylinder (20) by the first spring (22). The right end of the connecting cylinder (20) is pressed against the connecting plate (23). The two ends of the second spring (24) are elastically connected to the filter cylinder (11) and the connecting plate (23) respectively.

6. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: The first filter hole (12) is opened on the outer surface of the filter cylinder (11), and the second filter hole (13) is opened on the right side of the filter cylinder (11). The diameter of the second filter hole (13) is greater than the diameter of the first filter hole (12).

7. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: The first spring (22) is compressed and disposed inside the connecting cylinder (20) by the connecting column (21), and the second spring (24) is in a stretched state under the initial conditions.

8. A mixed-flow pump with a sewage pretreatment device according to claim 1, characterized in that: The diameter of the narrowest part of the third filter hole (17) is greater than the diameter of the second filter hole (13).

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