Axial flow pump

Abstract

The application provides an axial flow pump, which comprises a mounting base, a stator, a rotor and an impeller, the mounting base is provided with a mounting cavity, the stator is arranged in the mounting cavity, the stator is provided with a rotor cavity, the rotor is arranged in the rotor cavity, the rotor is provided with a structure cavity, the impeller is arranged in the structure cavity and the impeller is coaxially arranged with the rotor, the blades of the impeller are fixedly connected with the rotor, and the rotor is rotationally connected with the mounting base through a radial magnetic suspension bearing. The application can simplify the structure of the axial flow pump.

Description

Technical Field

[0001] This invention relates to the field of pump technology, and in particular to an axial flow pump. Background Technology

[0002] Marine pumps are a diverse and numerous type of mechanical equipment that plays a vital role. A certain number of marine pumps are required to perform primary or auxiliary tasks in ship propulsion systems, cargo handling, living services, safety systems, other specialized systems, and auxiliary devices. Among these, axial flow pumps are a commonly used type of marine pump.

[0003] Existing marine axial flow pumps typically employ a separate drive motor, whose output shaft drives the impeller to rotate, thereby pumping the fluid. This separate drive motor and impeller design results in drawbacks such as complex structure, numerous parts, high failure rate, large footprint, and heavy weight.

[0004] Based on this, existing technology proposes an axial flow pump in which the rotor of the drive motor is directly connected to the impeller. Specifically, the axial flow pump has a stator installed inside the sleeve, and the rotor is located inside the stator. The rotor and the impeller blades are directly connected. When the rotor rotates relative to the stator, it directly drives the impeller to rotate, thereby simplifying the structure, reducing the number of parts, lowering the failure rate, reducing the space occupied, and reducing weight. However, this type of axial flow pump has significant vibration and noise.

[0005] To further reduce vibration and noise, a magnetic-fluid composite suspension bearing-supported axial flow pump has been proposed in the prior art. Specifically, the rotor is radially supported on the end cover by a hydraulic bearing through fluid pressure, and axial support is achieved through a magnetic suspension bearing. Since both support methods are non-contact during the operation of the axial flow pump, vibration and noise can be significantly reduced. However, during startup acceleration and shutdown deceleration, the centrifugal force of this bearing pump weakens, and the supporting force generated by the high-pressure water is insufficient to overcome the gravity of the rotor assembly and propeller. At this time, it is in a state of sliding friction. To avoid the formation of sliding friction, high-pressure water can be directly pumped in by a high-pressure water pump with an external inlet, which leads to the complexity of the axial flow pump structure.

[0006] Therefore, existing axial flow pumps need to be improved to simplify their structure. Summary of the Invention

[0007] The purpose of this invention is to provide an axial flow pump to solve the problem of the complex structure of existing axial flow pumps.

[0008] To solve the above-mentioned technical problems, the present invention provides an axial flow pump, including a mounting base, a stator, a rotor, and an impeller. The mounting base has a mounting cavity, the stator is disposed in the mounting cavity, the stator has a rotor cavity, the rotor is disposed in the rotor cavity, the rotor has a structural cavity, the impeller is disposed in the structural cavity and the impeller and the rotor are coaxially arranged, the blades of the impeller are fixedly connected to the rotor, and the rotor is rotatably connected to the mounting base through a radial magnetic levitation bearing.

[0009] Optionally, the mounting base includes a sleeve, a first end cap, and a second end cap. The first end cap and the second end cap are respectively disposed at the two end faces of the sleeve, and the first end cap and the second end cap are respectively connected to the sleeve. The sleeve, the first end cap, and the second end cap form the mounting cavity.

[0010] Optionally, the first end cap has a first annular groove on its end face facing the rotor, and the second end cap has a second annular groove on its end face facing the rotor; the rotor has a first protrusion extending into the first annular groove and a second protrusion extending into the second annular groove; the number of radial magnetic bearings is two, one radial magnetic bearing is disposed at the radial gap between the inner ring of the first protrusion and the inner ring of the first annular groove, and the other radial magnetic bearing is disposed at the radial gap between the inner ring of the second protrusion and the inner ring of the second annular groove.

[0011] Optionally, it also includes an axial magnetic bearing, through which the rotor is connected to the mounting base.

[0012] Optionally, the axial magnetic levitation bearing is disposed at the radial gap between the first protrusion and the first annular groove or at the radial gap between the second protrusion and the second annular groove.

[0013] Optionally, it also includes a pair of radial protection bearings, one of which is disposed at the radial gap between the first protrusion and the first annular groove, and the other of which is disposed at the radial gap between the second protrusion and the second annular groove. The outer diameter of the radial protection bearing located at the radial gap between the first protrusion and the first annular groove is larger than the outer diameter of the radial magnetic levitation bearing before it is energized, and the outer diameter of the radial protection bearing located at the radial gap between the second protrusion and the second annular groove is larger than the outer diameter of the radial magnetic levitation bearing before it is energized.

[0014] Optionally, it also includes a mud and sand prevention device, which is disposed in the gap between the first end cover and the rotor, and in the gap between the second end cover and the rotor.

[0015] Optionally, a first floating seal groove is provided on the end face of the first end cover facing the rotor, and a second floating seal groove is provided on the end face of the rotor facing the first end cover. The diameter of the first floating seal groove is smaller than the diameter of the first annular groove. The anti-mud and sand device includes a first floating seal structure, which is disposed in the first floating seal groove and the second floating seal groove.

[0016] Optionally, a third floating seal groove is provided on the end face of the second end cover facing the rotor, and a fourth floating seal groove is provided on the end face of the rotor facing the second end cover. The diameter of the third floating seal groove is smaller than the diameter of the second annular groove. The anti-mud and sand device also includes a second floating seal structure, which is disposed in the third floating seal groove and the fourth floating seal groove.

[0017] Optionally, the anti-sediment device includes a first reverse osmosis membrane structure and a second reverse osmosis membrane structure for isolating sediment, wherein the first reverse osmosis membrane structure is disposed in the first annular groove and the second reverse osmosis membrane structure is disposed in the second annular groove.

[0018] The axial flow pump provided by this invention has the following beneficial effects:

[0019] Since the rotor is rotatably connected to the mounting base via the radial magnetic levitation bearing, it can be supported by the radial magnetic levitation bearing. Thus, regardless of the operating conditions of the axial flow pump, the radial magnetic levitation bearing can provide non-contact support to the rotor. Therefore, it can improve the stability of the axial flow pump while reducing vibration and noise. Because high-pressure water is not required, the structure can be simplified. Furthermore, the isolation effect between the stator and rotor is more significant than that of a conventional motor, resulting in a more pronounced noise reduction effect. Attached Figure Description

[0020] Figure 1 This is a cross-sectional structural schematic diagram of the axial flow pump in an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A magnified view of a portion at point A;

[0022] Figure 3 This is the first reverse osmosis membrane structure of the axial flow pump in another embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 100 - Mounting base; 110 - Sleeve;

[0025] 120 - First end cap; 121 - First annular groove; 122 - First floating seal groove;

[0026] 130 - Second end cap; 131 - Second annular groove; 132 - Third floating seal groove;

[0027] 200-Stator; 210-Encapsulation; 220-Winding; 230-Stator sheath; 240-Stator core;

[0028] 300 - Rotor; 310 - First protrusion; 320 - Second protrusion; 330 - Permanent magnet; 340 - Second floating seal groove; 350 - Fourth floating seal groove;

[0029] 400-Impeller;

[0030] 510 - Radial magnetic levitation bearing; 520 - Axial magnetic levitation bearing; 530 - Radial protective bearing;

[0031] 600 - First floating seal structure; 610 - First floating seal seat; 620 - First rubber ring; 630 - First floating seal ring; 640 - First end face; 650 - Second floating seal seat; 660 - Second rubber ring; 670 - Second floating seal ring; 680 - Second end face;

[0032] 600 - Second floating seal structure;

[0033] 700 - First reverse osmosis membrane structure; 710 - First reverse osmosis membrane support; 720 - First wear-resistant ring; 730 - First reverse osmosis membrane. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] refer to Figure 1 and Figure 2 , Figure 1 This is a cross-sectional structural diagram of the axial flow pump in an embodiment of the present invention. Figure 2 yes Figure 1 In the enlarged schematic diagram at point A, this embodiment provides an axial flow pump, including a mounting base 100, a stator 200, a rotor 300, and an impeller 400. The mounting base 100 has a mounting cavity, the stator 200 is disposed in the mounting cavity, the stator 200 has a rotor cavity, the rotor 300 is disposed in the rotor cavity, the rotor 300 has a structural cavity, the impeller 400 is disposed in the structural cavity, and the impeller 400 and the rotor 300 are coaxially arranged. The blades of the impeller 400 are fixedly connected to the rotor 300, and the rotor 300 is rotatably connected to the mounting base 100 through a radial magnetic levitation bearing 510.

[0041] Since the rotor 300 is rotatably connected to the mounting base 100 via the radial magnetic levitation bearing 510, the rotor 300 can be supported by the radial magnetic levitation bearing 510. Thus, during the operation of the axial flow pump, regardless of the operating condition of the axial flow pump, the radial magnetic levitation bearing 510 can provide non-contact support for the rotor 300. Therefore, the stability of the axial flow pump can be improved while reducing vibration and noise. Since there is no need to install high-pressure water, the structure can be simplified.

[0042] refer to Figure 1 The mounting base 100 includes a sleeve 110, a first end cap 120, and a second end cap 130. The first end cap 120 and the second end cap 130 are respectively disposed on the two end faces of the sleeve 110, and the first end cap 120 and the second end cap 130 are respectively connected to the sleeve 110. The sleeve 110, the first end cap 120, and the second end cap 130 form the mounting cavity.

[0043] In this embodiment, the mounting base 100 is installed on the inner wall of the pipe.

[0044] Preferably, the first end cap 120 has a first annular groove 121 on its end face facing the rotor 300, and the second end cap 130 has a second annular groove 131 on its end face facing the rotor 300. The rotor 300 has a first protrusion 310 extending into the first annular groove 121 and a second protrusion 320 extending into the second annular groove 131. The number of radial magnetic levitation bearings 510 is two. One radial magnetic levitation bearing 510 is disposed at the radial gap between the inner ring of the first protrusion 310 and the inner ring of the first annular groove 121, and the other radial magnetic levitation bearing 510 is disposed at the radial gap between the inner ring of the second protrusion 320 and the inner ring of the second annular groove 131.

[0045] The axial flow pump also includes an axial magnetic levitation bearing 520, and the rotor 300 is connected to the mounting base 100 through the axial magnetic levitation bearing 520.

[0046] The axial magnetic levitation bearing 520 is disposed at the radial gap between the first protrusion 310 and the first annular groove 121 or at the radial gap between the second protrusion 320 and the second annular groove 131.

[0047] In this embodiment, the stators of both the radial magnetic bearing 510 and the axial magnetic bearing 520 include electromagnets. That is, both the radial magnetic bearing 510 and the axial magnetic bearing 520 require power to function properly.

[0048] The axial flow pump also includes a pair of radial protection bearings 530. One radial protection bearing 530 is disposed at the radial gap between the first protrusion 310 and the first annular groove 121, and the other radial protection bearing 530 is disposed at the radial gap between the second protrusion 320 and the second annular groove 131. The outer diameter of the radial protection bearing 530 located at the radial gap between the first protrusion 310 and the first annular groove 121 is larger than the outer diameter of the radial magnetic levitation bearing 510 before it is energized, and the outer diameter of the radial protection bearing 530 located at the radial gap between the second protrusion 320 and the second annular groove 131 is larger than the outer diameter of the radial magnetic levitation bearing 510 before it is energized. Thus, when the radial magnetic levitation bearing 510 is not energized, the rotor 300 of the axial flow pump is supported on the first end cover 120 and the second end cover 130 by the radial protection bearings 530, thereby protecting the radial magnetic levitation bearing 510.

[0049] The rotor 300 is provided with a permanent magnet 330.

[0050] The permanent magnets 330 are arranged in a Halbach permanent magnet array with a unilateral magnetic focusing effect.

[0051] The rotor 300 is constructed of corrosion-resistant stainless steel.

[0052] A rotor sheath is provided on the outer peripheral surface of the rotor 300. The rotor sheath is preferably made of titanium alloy.

[0053] The stator 200 includes an encapsulation body 210 and a winding 220. The encapsulation body 210 covers the winding 220 and has a rotor cavity.

[0054] The stator 200 also includes a stator sheath 230 disposed on the inner wall of the encapsulation body 210.

[0055] The stator 200 also includes a stator core. The stator core is made of stacked silicon steel sheets.

[0056] The encapsulation body 210 is made of epoxy resin, and the stator sheath 230 is made of titanium alloy.

[0057] The wires of the external circuit enter the sleeve 110 and stator 200 through the underwater sealed plug and then through the sealed channel, and are connected to the winding 220.

[0058] The impeller 400 is constructed of corrosion-resistant stainless steel. The blades feature a low-cavitation design, and the blade tip thickness is appropriately increased to reduce fluid noise in the device.

[0059] The axial flow pump also includes a position sensor for detecting the axial position of the rotor 300 and a controller connected to the position sensor. When the rotor 300 shifts position, the position sensor transmits a signal to the controller, which controls the current in the coil of the stator of the axial magnetic levitation bearing 520 to change the thrust on the rotor 300 of the axial magnetic levitation bearing 520, thereby adjusting the position of the rotor 300.

[0060] In this embodiment, the axial flow pump further includes a mud and sand prevention device, which is disposed in the gap between the first end cover 120 and the rotor 300, and in the gap between the second end cover 130 and the rotor 300.

[0061] refer to Figure 1 and Figure 2 In this embodiment, a first floating seal groove 122 is formed on the end face of the first end cover 120 facing the rotor 300, and a second floating seal groove 340 is formed on the end face of the rotor 300 facing the first end cover 120. The diameter of the first floating seal groove 122 is smaller than the diameter of the first annular groove 121. The anti-sand device includes a first floating seal structure 600, which is disposed within the first floating seal groove 122 and the second floating seal groove 340. This seals the gap between the first floating seal groove 122 and the second floating seal groove 340, thereby sealing the gap between the first end cover 120 and the rotor 300. This prevents sand from entering the space between the rotor 300 and the stator 200 through the gap between the first end cover 120 and the rotor 300, thus affecting the performance of the axial flow pump.

[0062] Specifically, the first floating seal structure 600 includes a first floating seal seat 610, a first rubber ring 620, a first floating seal ring 630, a second floating seal seat 650, a second rubber ring 660, and a second floating seal ring 670. The first floating seal seat 610 is disposed on the inner ring of the first floating seal groove 122, the first floating seal ring 630 is disposed on the outer ring of the first floating seal groove 122 and sleeved on the first floating seal seat 610, the first rubber ring 620 is located between the first floating seal seat 610 and the first floating seal ring 630, and the second floating seal seat 650... The first floating seal ring 630 is disposed on the inner ring of the second floating seal groove 340, and the second floating seal ring 670 is disposed on the outer ring of the second floating seal groove 340 and sleeved on the second floating seal seat 650. The second rubber ring 660 is located between the second floating seal seat 650 and the second floating seal ring 670. The end face of the first floating seal ring 630 parallel to the end face of the rotor 300 is the first end face 640, and the end face of the second floating seal ring 670 parallel to the end face of the rotor 300 is the second end face 680. The first end face 640 and the second end face 680 are in contact. In this way, the gap between the first end cover 120 and the rotor 300 can be sealed.

[0063] In this embodiment, a third floating seal groove 132 is further formed on the end face of the second end cover 130 facing the rotor 300, and a fourth floating seal groove 350 is formed on the end face of the rotor 300 facing the second end cover 130. The diameter of the third floating seal groove 132 is smaller than the diameter of the second annular groove 131. The anti-sand device also includes a second floating seal structure 600, which is disposed within the third floating seal groove 132 and the fourth floating seal groove 350. Thus, the gap between the third floating seal groove 132 and the fourth floating seal groove 350 can be sealed, thereby sealing the gap between the second end cover 130 and the rotor 300, preventing sand from entering between the rotor 300 and the stator 200 through the gap between the second end cover 130 and the rotor 300, thus affecting the performance of the axial flow pump.

[0064] Specifically, the second floating seal structure 600 includes a third floating seal seat, a third rubber ring, a third floating seal ring, a fourth floating seal seat, a fourth rubber ring, and a fourth floating seal ring. The third floating seal seat is disposed on the inner ring of the third floating seal groove 132, and the third floating seal ring is disposed on the outer ring of the third floating seal groove 132 and sleeved on the third floating seal seat. The third rubber ring is located between the third floating seal seat and the third floating seal ring. The fourth floating seal seat is disposed on the inner ring of the fourth floating seal groove 350, and the fourth floating seal ring is disposed on the outer ring of the fourth floating seal groove 350 and sleeved on the fourth floating seal seat. The fourth rubber ring is located between the fourth floating seal seat and the fourth floating seal ring. The end face of the third floating seal ring parallel to the end face of the rotor 300 is the third end face, and the end face of the fourth floating seal ring parallel to the end face of the rotor 300 is the fourth end face. The third end face and the fourth end face are in contact. In this way, the gap between the second end cap 130 and the rotor 300 can be sealed.

[0065] In one embodiment, the anti-sediment device includes a first mechanical seal structure disposed within the first annular groove 121. In another embodiment, the anti-sediment device includes a second mechanical seal structure disposed within the second annular groove 131. Preferably, the first mechanical seal structure is disposed closer to the rotor 300 than the radial magnetic levitation bearing 510 and the radial protective bearing 530. The second mechanical seal structure is disposed closer to the rotor 300 than the radial magnetic levitation bearing 510, the axial magnetic levitation bearing 520, and the radial protective bearing 530. Both the first and second mechanical seal structures employ mechanical seals.

[0066] In another embodiment, the sediment-prevention device includes a first reverse osmosis membrane structure 700 for isolating sediment, the first reverse osmosis membrane structure 700 being disposed within the first annular groove 121. In yet another embodiment, the sediment-prevention device further includes a second reverse osmosis membrane structure, the second reverse osmosis membrane structure being disposed within the second annular groove 131. Specifically, refer to... Figure 3 , Figure 3This invention relates to a first reverse osmosis membrane structure 700 for an axial flow pump, comprising a first reverse osmosis membrane support 710, a first wear-resistant ring 720, and a first reverse osmosis membrane 730. The first reverse osmosis membrane support 710 is disposed within the inner ring of the first annular groove 121, and the first wear-resistant ring 720 is disposed within the inner ring of the first protrusion 310. The first reverse osmosis membrane support 710 and the first wear-resistant ring 720 are rotatably connected and in contact with each other. The first reverse osmosis membrane 730 is disposed on the first reverse osmosis membrane support 710. The second reverse osmosis membrane structure comprises a second reverse osmosis membrane support, a second wear-resistant ring, and a second reverse osmosis membrane. The second reverse osmosis membrane support is disposed within the inner ring of the second annular groove 131, and the second wear-resistant ring is disposed within the inner ring of the second protrusion 320. The second reverse osmosis membrane support and the second wear-resistant ring are rotatably connected and in contact with each other. The second reverse osmosis membrane is disposed on the second reverse osmosis membrane support. Thus, the first reverse osmosis membrane support 710 and the first wear-resistant ring 720 can rotate and seal against each other, allowing water to be filtered through the first reverse osmosis membrane 730 to remove impurities and sediment. Similarly, the second reverse osmosis membrane support and the second wear-resistant ring can rotate and seal against each other, allowing water to be filtered through the second reverse osmosis membrane to remove impurities and sediment.

[0067] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. An axial flow pump, comprising a mounting base, a stator, a rotor, and an impeller, wherein the mounting base has a mounting cavity, and the stator is disposed within the mounting cavity, characterized in that, The stator has a rotor cavity, the rotor is disposed within the rotor cavity, the rotor has a structural cavity, the impeller is disposed within the structural cavity and is coaxially arranged with the rotor, the blades of the impeller are fixedly connected to the rotor, and the rotor is rotatably connected to the mounting base via a radial magnetic levitation bearing; the mounting base includes a sleeve, a first end cover and a second end cover, the first end cover and the second end cover are respectively disposed at the two end faces of the sleeve, and the first end cover and the second end cover are respectively connected to the sleeve, the sleeve, the first end cover and the second end cover form the mounting cavity; a first annular groove is formed on the end face of the first end cover facing the rotor, and a second annular groove is formed on the end face of the second end cover facing the rotor; the rotor has a first protrusion extending into the first annular groove and a second protrusion extending into the second annular groove; the number of radial magnetic levitation bearings is two, one of which is disposed between the inner ring of the first protrusion and the inner ring of the first annular groove. The rotor is connected to the mounting base via the axial magnetic bearing, which is located at the radial gap between the first protrusion and the first annular groove or at the radial gap between the second protrusion and the second annular groove. The rotor is also connected to the mounting base via the axial magnetic bearing, which is located at the radial gap between the first protrusion and the first annular groove or at the radial gap between the second protrusion and the second annular groove. The rotor is also connected to the mounting base via the axial magnetic bearing, which is located at the radial gap between the first protrusion and the first annular groove, and at the radial gap between the second protrusion and the second annular groove. The outer ring diameter of the radial protective bearing located at the radial gap between the first protrusion and the first annular groove is larger than the outer ring diameter of the radial magnetic bearing before energization, and the outer ring diameter of the radial protective bearing located at the radial gap between the second protrusion and the second annular groove is larger than the outer ring diameter of the radial magnetic bearing before energization.

2. The axial flow pump as described in claim 1, characterized in that, It also includes a mud and sand prevention device, which is installed in the gap between the first end cover and the rotor, and in the gap between the second end cover and the rotor.

3. The axial flow pump as described in claim 2, characterized in that, The first end cover has a first floating seal groove on its end face facing the rotor, and the rotor has a second floating seal groove on its end face facing the first end cover. The diameter of the first floating seal groove is smaller than the diameter of the first annular groove. The anti-mud and sand device includes a first floating seal structure, which is disposed in the first floating seal groove and the second floating seal groove.

4. The axial flow pump as described in claim 3, characterized in that, The second end cover has a third floating seal groove on its end face facing the rotor, and the rotor has a fourth floating seal groove on its end face facing the second end cover. The diameter of the third floating seal groove is smaller than the diameter of the second annular groove. The anti-mud and sand device also includes a second floating seal structure, which is disposed in the third floating seal groove and the fourth floating seal groove.

5. The axial flow pump as described in claim 2, characterized in that, The silt-prevention device includes a first reverse osmosis membrane structure and a second reverse osmosis membrane structure for isolating silt. The first reverse osmosis membrane structure is disposed in the first annular groove, and the second reverse osmosis membrane structure is disposed in the second annular groove.

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