High lift self-priming centrifugal pump

Abstract

The application provides a high-suction self-priming centrifugal pump, comprising a pump body and an impeller, the pump body has a volute inside, the impeller is located in the volute, and the impeller is driven to rotate by a power device; a water storage space is arranged at the outlet of the pump body, the outlet of the volute extends into the water storage space through a flow guide channel; an air-liquid mixing device is arranged between the inlet of the volute and the inlet of the pump body, air on the inner wall of the inlet is sucked into the air-liquid mixing device by using the pressure difference formed in the liquid flow process; a circulation channel is arranged in the volute and communicates with the air-liquid mixing device, and is used for forming a backflow jet flow; the backflow jet flow is used for carrying out secondary shearing and mixing on the air-liquid mixed flow. The whole design is simple, the manufacturing and maintenance costs are low, the high-suction self-priming ability can be maintained under complex working conditions, and the defects of slow exhaust, difficult start and limited suction of the existing self-priming centrifugal pump can be effectively overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of centrifugal pumps, in particular to a high suction range self-priming centrifugal pump. BACKGROUND

[0002] As one of the most widely used fluid conveying devices in industrial and civil fields, centrifugal pumps rely on the centrifugal force generated by the high-speed rotation of the impeller to realize the lifting and conveying of liquid. Self-priming centrifugal pumps, as an important branch of centrifugal pumps, have the core advantage that after the first start completes the priming, subsequent start does not need to repeat priming, and can automatically remove the gas in the suction pipeline, restoring the normal liquid conveying function. Therefore, it plays an irreplaceable role in agricultural irrigation, municipal drainage, industrial circulation and emergency firefighting, etc. which need frequent start-stop or complex suction conditions.

[0003] Although self-priming centrifugal pumps have significant operational convenience, their technical development has long faced several bottlenecks. In the prior art, to achieve self-priming function, the most common solution is to set a liquid storage cavity or an additional independent gas-liquid separation chamber in the pump body. The liquid storage cavity pre-reserves part of the liquid in the pump body, and when the pump starts, it forms a gas-liquid mixture by stirring with the impeller, and preliminary separation of gas and liquid is achieved by density difference. The gas is discharged and the liquid flows back to participate in the next cycle. The gas-liquid separation device reduces the flow rate by increasing the flow passage volume, changing the flow direction, etc. to promote the escape of gas from the liquid and be directed to the outlet. However, both of these two mainstream technical paths have inherent limitations. First, the gas discharge process relies on the kinetic energy of the fluid itself and gravity differentiation, and the gas discharge efficiency is generally low, resulting in a long start-up time of the pump, which is difficult to meet the needs of fast response working conditions. Second, this structure has a high requirement for the amount of liquid before the first start, and if the liquid storage is insufficient or the priming is not complete, the self-priming process is prone to failure, and even may cause dry grinding. Third, the additional liquid storage cavity or separation device not only increases the structural complexity and casting difficulty of the pump body, but also increases the material cost and manufacturing cost, to some extent, limiting its popularization and application.

[0004] In addition, the prior art has disclosed an improved self-priming centrifugal pump, which is provided with a water suction cavity in the pump body, and the water outlet pipe and the multiple component water inlet pipe are communicated with the upper and lower ends of the water suction cavity respectively, trying to optimize the water flow distribution state of the suction end. Although this design improves the water suction uniformity of the conventional structure to some extent, its self-priming efficiency, especially in the critical gas removal stage at the initial start-up, is still insufficient. The fundamental reason is that this structure fails to achieve active and efficient treatment of the suction air. When encountering serious air accumulation in the suction pipeline, sudden increase of inlet air volume, or complex working conditions such as the presence of trace impurities in the conveying medium affecting the stability of the gas-liquid interface, this technical solution exposes obvious short boards in terms of exhaust thoroughness and speed. Air cannot be effectively broken into fine bubbles and fully mixed with liquid, resulting in air accumulation in the pump, forming air resistance, which not only reduces the efficiency and flow of the pump, but also may cause vibration and noise, affecting the stability and reliability of operation.

[0005] In summary, the existing self-priming centrifugal pump technology generally faces a series of interrelated technical problems such as low exhaust efficiency, long start-up time, strong dependence on initial liquid filling, high manufacturing cost, and insufficient running stability under complex working conditions. The core of these problems lies in the lack of an internal mechanism that can actively and efficiently treat the suction air and achieve rapid and thorough exhaust. Therefore, the industry urgently needs an innovative solution that can fundamentally improve the suction capacity, exhaust efficiency and start-up speed of the self-priming centrifugal pump while ensuring a simple structure and controllable cost, to adapt to more demanding and diverse application environments. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a high-suction self-priming centrifugal pump, which sets a gas-liquid mixing device between the suction inlet (inlet) and the impeller, actively sucks and breaks the air using the pressure difference formed by the liquid flow, and realizes multiple gas-liquid mixing and exhaust through the circulation channel, so that the air in the pump cavity is timely removed, forming a stable negative pressure area, thereby significantly improving the self-priming speed and exhaust efficiency, and improving the suction performance of the pump. The overall design of the present application is simple, and the manufacturing and maintenance costs are low. It can maintain high suction capacity under complex working conditions, effectively overcoming the deficiencies of slow exhaust, difficult start-up and limited suction range of the existing self-priming centrifugal pump.

[0007] The present application achieves the above technical objects by the following technical means.

[0008] The utility model provides a high self-priming centrifugal pump, comprising a pump body and an impeller, the pump body has a volute in it, the impeller is located in the volute, and the impeller is driven to rotate by a power device;An outlet of the pump body is provided with a water storage space, and an outlet of the volute extends into the water storage space through a drainage channel;An air-liquid mixing device is arranged between an inlet of the volute and an inlet of the pump body, and air in the inner wall of the inlet is sucked into the air-liquid mixing device by using the pressure difference formed during the flow of liquid;A circulation channel is communicated with the air-liquid mixing device in the volute for forming a backflow jet flow, and the backflow jet flow is used for secondary shearing and mixing of the air-liquid mixed flow.

[0009] Further, the air-liquid mixing device comprises a first chamber and a second chamber, and the inlet of the volute and the inlet of the pump body are divided into the first chamber and the second chamber by a baffle;The second chamber is communicated with the inlet of the pump body, and the first chamber is communicated with the second chamber through an air suction hole;The baffle is provided with a plurality of air mixing holes communicated with the second chamber, air in the inner wall of the inlet is sucked into the first chamber through the air suction hole by using the pressure difference formed during the flow of liquid, and the air is sheared and broken at the air mixing hole of the second chamber, and then enters the volute after being mixed with the liquid.

[0010] Further, the baffle comprises a center sleeve and a cover plate, one end of the center sleeve is connected with the inlet of the volute, and the other end of the center sleeve is provided with the cover plate, the edge of the cover plate extends to the inner wall of the pump body, and the edge of the cover plate is provided with at least one air suction hole, and the wall surface of the center sleeve is provided with a plurality of air mixing holes.

[0011] Further, the air mixing hole is an inclined tapered hole, and the included angle between the center line of the air mixing hole and the flow direction is an acute angle.

[0012] Further, the outlet of the circulation channel is provided with a spiral acceleration device, the spiral acceleration device comprises a tapered spiral guide vane, the outlet of the circulation channel is tapered along the flow direction, and the tapered spiral guide vane is located at the tapered outlet of the circulation channel;The backflow jet flow formed by the outlet of the circulation channel is aligned with the second chamber.

[0013] Further, a backflow channel is arranged between the water storage space and the volute, and the outlets of the drainage channels are staggered with the outlet of the pump body, so that the fluid can flow back to the volute through the backflow channel.

[0014] Further, the backflow channel is a one-way channel in the form of a Tesla valve, which is used for preventing the fluid from entering the water storage space through the backflow channel.

[0015] Further, the water storage space is provided with a water injection hole, water is injected into the volute through the water injection hole, so that the liquid level is at least submerged in the impeller, and the self-priming effect during starting is ensured.

[0016] The utility model has the advantages that:

[0017] 1. The high-suction self-priming centrifugal pump of the present application, by setting a unique gas-liquid mixing device between the inlet of the volute and the inlet of the pump body, and setting a circulating channel communicating with the volute, using the local pressure difference formed at the gas-liquid mixing device by the liquid flow driven by the impeller during pump operation, actively sucking the air on the inner wall of the pump body inlet into the first chamber through the air suction hole, and then the sucked air is forced to pass through a plurality of gas mixing holes (especially preferably inclined tapered holes) provided on the baffle at the second chamber, in the process, the high-speed liquid flow shears and breaks the air violently, forming a fine and uniform gas-liquid mixture, thereby realizing a leap in exhaust efficiency and self-priming speed, solving the problems of low exhaust efficiency and slow self-priming speed.

[0018] 2. The high-suction self-priming centrifugal pump of the present application, the circulating channel leads the high-pressure fluid in the volute back to the inlet near the gas-liquid mixing device (second chamber), forming a high-speed backflow jet. This backflow jet shears and mixes the gas-liquid flow after the first mixing, making the gas bubbles be crushed more thoroughly, greatly increasing the gas-liquid contact area, and accelerating the dissolution and entrainment of gas in the liquid.

[0019] 3. The high-suction self-priming centrifugal pump of the present application, by the combination of active air suction, one-time shearing and breaking, and secondary mixing enhancement, it ensures that the air in the pump cavity can be mixed quickly and thoroughly and discharged with the liquid, thereby forming and maintaining a stable negative pressure zone at the suction inlet, significantly improving the exhaust efficiency and self-priming speed, and shortening the start-up time.

[0020] 4. The high-suction self-priming centrifugal pump of the present application, a water storage space is provided at the outlet of the pump body, and the liquid can enter the space for temporary storage through the drainage channel. A dedicated water injection hole is provided on the water storage space. The setting of the water storage space and the convenient water injection hole simplify the pump filling operation and reduce the dependence on the accuracy of the initial liquid filling. Combined with the assistance of the backflow channel, it ensures that the pump can quickly establish effective circulation and achieve rapid start-up even in the case of a large amount of gas in the suction pipeline, solving the problems of long start-up time and strong dependence on initial liquid filling.

[0021] 5. The high-suction self-priming centrifugal pump of the present application, by setting a backflow channel (preferably a Tesla valve type one-way channel) between the water storage space and the volute, during the process of establishing pressure head during pump start-up, part of the liquid can be guided to flow back to the volute to participate in circulation, further assisting the carrying and exclusion of initial gas.

[0022] 6. The high suction self-priming centrifugal pump of the present application, the gas-liquid mixing device (composed of a central sleeve, a cover plate, an air suction hole, a gas mixing hole, etc.) is directly integrated in the flow channel between the pump body inlet and the volute inlet, with compact structure, without the need for an additional large and complex external gas-liquid separation tank or special valve group; the circulation channel, the backflow channel, etc. are all realized by using the internal or attached cavity structure of the pump body, with reasonable layout, avoiding excessive external pipelines and connectors. This highly integrated design makes the pump body structure relatively simple, with better casting and machining process, effectively controlling the material cost and manufacturing cost, while improving the reliability of the system.

[0023] 7. The high suction self-priming centrifugal pump of the present application, through multiple gas-liquid mixing and shearing mechanisms (primary shearing by the gas mixing hole + secondary mixing by the backflow jet flow in the circulation channel), it can effectively break and entrain gas even when the inlet air volume is large or the medium conditions are poor, better adapting to complex working conditions such as inlet pressure fluctuations and gas content changes, and showing better operation stability and reliability.

[0024] 8. The high suction self-priming centrifugal pump of the present application, a one-way channel with a Tesla valve structure is provided at the backflow hole, which can effectively prevent reverse flow of the fluid, ensure the one-way nature and circulation stability of the backflow path, and thus maintain the continuity of the gas-liquid mixing process and the stability of the high suction operation of the pump body. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. The drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0026] Figure 1 The high suction self-priming centrifugal pump structure diagram of the present application.

[0027] Figure 2 The internal flow direction diagram of the high suction self-priming centrifugal pump of the present application.

[0028] Figure 3 The gas-liquid mixing device structure diagram of the present application.

[0029] Figure 4 The spiral mixing device structure diagram of the present application.

[0030] Figure 5 The high suction self-priming centrifugal pump along the outlet centerline sectional view of the present application.

[0031] Figure 6Fig. 1 is a schematic diagram of the cross-sectional flow direction along the outlet centerline of the high suction lift self-priming centrifugal pump according to the present application.

[0032] Figure 7 Fig. 2 is a schematic diagram of the backflow passage of the high suction lift self-priming centrifugal pump according to the present application.

[0033] Fig. 1 is a schematic diagram of the cross-sectional flow direction along the outlet centerline of the high suction lift self-priming centrifugal pump according to the present application.

[0034] 1-pump body; 2-volute; 3-inlet; 4-suction hole; 5-gas-liquid mixing device; 5-1-baffle; 5-1-1-center sleeve; 5-1-2-cover plate; 5-2-first chamber; 5-3-second chamber; 5-4-gas mixing hole; 6-drainage passage; 7-water storage space; 8-spiral accelerating device; 9-circulation passage; 10-impeller; 11-seal assembly; 12-motor; 13-backflow passage; 14-seal cover; 15-outlet; 16-water injection hole. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments described below are examples for explaining the present application and should not be construed as limiting the present application.

[0036] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be construed as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0037] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing", etc. should be understood in a broad sense, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] As Figure 1 and Figure 2 shown, the high-suction self-priming centrifugal pump of the application includes a pump body 1 and an impeller 10, the pump body 1 has a volute 2 inside, the impeller 10 is located in the volute 2, and the impeller 10 is driven to rotate by a power device; a general motor 12 is connected with a rotating shaft through a shaft coupling, the rotating shaft is connected with the impeller 10, and a sealing assembly 11 is arranged between the rotating shaft and the pump body 1 for sealing, and the general sealing assembly 11 is a mechanical seal; a water storage space 7 is arranged at an outlet 15 of the pump body 1, and an outlet of the volute 2 extends into the water storage space 7 through a drainage channel 6; an air-liquid mixing device 5 is arranged between an inlet of the volute 2 and an inlet of the pump body 1, and the air in the inner wall of the inlet 3 is sucked into the air-liquid mixing device 5 by using the pressure difference formed in the liquid flow process; the volute 2 is communicated with the air-liquid mixing device 5 through a circulation channel 9 for forming a backflow jet flow, and the backflow jet flow is used for secondary shearing and mixing of the air-liquid mixed flow. By means of the combined means of active air suction, primary shearing and breaking and secondary mixing enhancement, the air in the pump cavity can be rapidly and completely mixed and discharged with the liquid, so that a stable negative pressure area is formed and maintained at the suction inlet, the air exhaust efficiency and the self-priming speed are significantly improved, and the starting time is shortened.

[0039] As Figure 3 shown, the air-liquid mixing device 5 includes a first chamber 5-2 and a second chamber 5-3, and the inlet of the volute 2 and the inlet of the pump body 1 are divided into the first chamber 5-2 and the second chamber 5-3 by a baffle 5-1; the second chamber 5-3 is communicated with the inlet 3 of the pump body 1, the first chamber 5-2 is communicated with the second chamber 5-3 through an air suction hole 4; the baffle 5-1 is provided with a plurality of air mixing holes 5-4 communicated with the second chamber 5-3, and the air in the inner wall of the inlet 3 is sucked into the first chamber 5-2 through the air suction hole 4 by using the pressure difference formed in the liquid flow, and the air is sheared and broken at the air mixing hole 5-4 of the second chamber 5-3, and then enters the volute 2 after being mixed with the liquid. By means of the rotation of the impeller 10 driven by the motor 12, the local pressure difference formed in the air-liquid mixing device 5 by the liquid flow actively sucks the air in the inner wall of the pump body inlet 3 into the first chamber 5-2 through the air suction hole 4, and then the sucked air is forced to pass through the plurality of air mixing holes 5-4 arranged on the baffle 5-1 at the second chamber 5-3, in this process, the high-speed liquid flow shears and breaks the air violently to form fine and uniform air-liquid mixture, thereby realizing a leap-forward improvement of the air exhaust efficiency and the self-priming speed.

[0040] As Figure 3As shown, the baffle 5-1 includes a center sleeve 5-1-1 and a cover plate 5-1-2, one end of the center sleeve 5-1-1 is connected with the inlet of the volute 2; the other end of the center sleeve 5-1-1 is provided with the cover plate 5-1-2, the edge of the cover plate 5-1-2 extends to the inner wall of the pump body 1; the edge of the cover plate 5-1-2 is provided with at least one air suction hole 4, and the wall surface of the center sleeve 5-1-1 is provided with a plurality of mixed gas holes 5-4. The mixed gas hole 5-4 is an inclined tapered hole, the center line of the mixed gas hole 5-4 and the flow direction form an acute angle θ, and θ is generally 30-60°. The center sleeve and the cover plate of the present application can be directly integrated in the flow channel between the inlet of the pump body and the inlet of the volute, the structure is compact, and there is no need for an additional large and complex external gas-liquid separation tank or special valve group. In some embodiments, the center sleeve 5-1-1 is a sleeve tapered along the flow direction, and the cover plate 5-1-2 is inclined, so that the first chamber 5-2 formed by the pump body 1 is a chamber tapered along the flow direction.

[0041] As shown in Figure 4 , the outlet of the circulating channel 9 is provided with a spiral acceleration device 8, the spiral acceleration device 8 includes a tapered spiral guide vane, the outlet of the circulating channel 9 is tapered along the flow direction, and the tapered spiral guide vane is located at the tapered outlet of the circulating channel 9; the backflow jet formed by the outlet of the circulating channel 9 is aligned with the second chamber 5-3. The circulating channel 9 leads the high-pressure fluid in the volute 2 back to the vicinity of the inlet of the second chamber 5-3, forming a high-speed backflow jet. And the spiral acceleration device 8 can form a high-speed rotating jet, the high-speed rotating backflow jet performs secondary or even multiple shearing and mixing on the primary mixed gas-liquid flow, so that the gas bubbles are crushed more thoroughly, the gas-liquid contact area is greatly increased, and the dissolution and entrainment of the gas in the liquid are accelerated. In the embodiment, the flow rate of the backflow jet output by the spiral acceleration device 8 is generally 15 m / s-35 m / s, which is the best. If the flow rate is too low (<10 m / s), the kinetic energy of the jet is insufficient, and the primary mixed gas-liquid flow cannot be effectively sheared for the second time, and it is difficult to further tear the already preliminarily broken gas bubbles into finer and more stable bubbles. This will lead to insufficient gas-liquid mixing and reduce the exhaust efficiency. Although the shearing effect is stronger when the flow rate is too high (>40 m / s), the flow resistance (head loss) of the circulating channel and the jet device itself will increase sharply. This part of energy loss needs to be provided by the impeller additionally, which will reduce the overall efficiency of the pump, and it is not worth the loss. In the local low-pressure area, the high flow rate will significantly increase the risk of cavitation, which not only damages the overcurrent components (such as the spiral acceleration device, the impeller, etc.) of the pump, produces noise and vibration, but also destroys the stability of the flow field, and has a negative impact on the gas-liquid mixing process.

[0042] As shown in Figure 5 , Figure 6 , and Figure 7As shown, a water storage space 7 is provided at the outlet 15 of the pump body 1, and the outlet of the volute 2 extends into the water storage space 7 through a flow channel 6. A return channel 13 is provided between the water storage space 7 and the volute 2, and the outlets of the flow channel 6 and the pump body 1 outlet 15 are staggered to allow fluid to return to the volute 2 through the return channel 13. The return channel 13 is a Tesla valve type one-way channel to prevent fluid from entering the water storage space 7 through the return channel 13. A water injection hole 16 is provided on the water storage space 7, through which water is injected into the volute 2 so that the liquid level at least submerges the impeller 10 to ensure the self-priming effect during startup. This invention features a water storage space 7 at the pump outlet 15, with a flow channel 6 ensuring liquid can temporarily enter and be stored within it. The water storage space 7 has a dedicated water injection hole. This design, along with the convenient water injection hole 16, simplifies pump priming operations and reduces reliance on the accuracy of initial priming. Combined with the assistance of the return channel 13, this ensures that even with a large amount of gas in the suction line, the pump can quickly establish effective circulation, enabling rapid start-up and solving the problems of long start-up times and high dependence on initial priming. The water injection hole 16 is equipped with a sealing cap 14 to prevent dust or debris from entering when not in use.

[0043] like Figure 7 As shown in the embodiment, the return channel 13 is threadedly sealed on the pump body 1 in the form of a plug, and is installed between the water storage space 7 and the volute 2. The plug is equipped with a Tesla valve, which facilitates cleaning of the Tesla valve in the return channel 13.

[0044] The working principle is as follows:

[0045] Fluid enters the gas-liquid mixing channel 5 through pump inlet 3 and flows at high speed. Geometric contraction and velocity increase within the channel create localized low pressure before and after the mixing orifice 5-4. This pressure difference causes the suction holes 4 on the channel wall to actively draw air from the inner wall of inlet 3 into the channel. The drawn-in air, within the first chamber 5-2, comes into contact with the high-speed liquid flow at the mixing orifice 5-4 through a narrow channel. It is sheared and impacted, breaking into tiny bubbles that form a gas-liquid mixture. The central sleeve 5-1-1 guides this mixture accurately into the inlet position of impeller 10. The returning liquid enters the spiral mixing device 8 located at the circulation end through circulation channel 9. The high-speed liquid flow violently shears and breaks up the bubbles, forming a fine, uniform gas-liquid mixture. This mixture then re-enters the impeller through gas-liquid mixing device 5, forming multiple cycles of mixing until the gas in the pump chamber is fully exhausted. A Tesla valve-type one-way channel is installed in the return channel 13 to ensure that the return process is unidirectional, thus preventing reverse flow during the circulation phase from affecting exhaust efficiency. When the water storage space 7 is full, the pump enters the normal pressurization and delivery state, and the liquid is stably delivered through the outlet 15.

[0046] It should be understood that although the present specification is described in terms of various embodiments, each of which describes only one implementation, the specification is intended to cover all possible implementations that are within the scope of the application, which is defined by the claims. One skilled in the art will readily recognize from the disclosure herein, that alternative embodiments of the present application can be constructed from a number of approaches already known in the art, which do not depart from the spirit and scope of the present application. The individual features of the various embodiments of this application each will be recognized by one of ordinary skill in the art to be an innovative application that alone would entitle the applicant to a patent, but the present application is intended to cover each and every combination of the individual features disclosed herein and any other innovative feature that would be recognized by those of ordinary skill in the art to be an innovative application that alone would entitle the applicant to a patent. Therefore, the present application is not to be limited to only these explicitly disclosed embodiments.

[0047] The above detailed description merely describes preferred embodiments of the application, and is not intended to limit the scope of the application. What is desired to be protected by Letters Patent is set forth in the following claims, which are appended hereto.

Claims

1. A high lift self-priming centrifugal pump comprising a pump body (1) having a volute (2) therein and an impeller (10) located in the volute (2), the impeller (10) being driven to rotate by a power device; characterized in that, The outlet of the pump body (1) is provided with a water storage space (7), and the outlet of the volute (2) extends into the water storage space (7) through a drainage channel (6); an air-liquid mixing device (5) is arranged between the inlet of the volute (2) and the inlet of the pump body (1), and air in the inner wall of the inlet is sucked into the air-liquid mixing device (5) by using the pressure difference formed in the liquid flow process; the volute (2) is communicated with the air-liquid mixing device (5) through a circulation channel (9) for forming a backflow jet flow; the backflow jet flow is used for secondary shearing and mixing of the air-liquid mixed flow. The air-liquid mixing device (5) comprises a first chamber (5-2) and a second chamber (5-3), and the inlet of the volute (2) and the inlet of the pump body (1) are divided into the first chamber (5-2) and the second chamber (5-3) by a baffle (5-1); the second chamber (5-3) is communicated with the inlet of the pump body (1), and the first chamber (5-2) is communicated with the second chamber (5-3) through an air suction hole (4); a plurality of air mixing holes (5-4) are arranged on the baffle (5-1) and communicated with the second chamber (5-3), air in the inner wall of the inlet (3) is sucked into the first chamber (5-2) through the air suction hole (4) by using the pressure difference formed in the liquid flow process, and the air is sheared and broken at the air mixing hole (5-4) of the second chamber (5-3), and then mixed with the liquid to enter the volute (2).

2. The high head self-priming centrifugal pump of claim 1, wherein, The baffle (5-1) comprises a center sleeve (5-1-1) and a cover plate (5-1-2), one end of the center sleeve (5-1-1) is connected with the inlet of the volute (2); the other end of the center sleeve (5-1-1) is provided with the cover plate (5-1-2), and the edge of the cover plate (5-1-2) extends to the inner wall of the pump body (1); at least one air suction hole (4) is arranged on the edge of the cover plate (5-1-2), and a plurality of air mixing holes (5-4) are arranged on the wall surface of the center sleeve (5-1-1).

3. The high head self-priming centrifugal pump of claim 2, wherein, The air mixing hole (5-4) is an inclined tapered hole, and the included angle between the center line of the air mixing hole (5-4) and the flow direction is an acute angle.

4. The high head self-priming centrifugal pump of claim 1, wherein, The outlet of the circulation channel (9) is provided with a spiral acceleration device (8), the spiral acceleration device (8) comprises a tapered spiral guide vane, the outlet of the circulation channel (9) is tapered along the flow direction, and the tapered spiral guide vane is located at the tapered outlet of the circulation channel (9); the backflow jet flow formed by the outlet of the circulation channel (9) is aligned with the second chamber (5-3).

5. The high head self-priming centrifugal pump of claim 1, wherein, A backflow channel (13) is arranged between the water storage space (7) and the volute (2), and the outlets of the drainage channels (6) and the outlet (15) of the pump body (1) are staggered for fluid backflow to the volute (2) through the backflow channel (13).

6. The high head self-priming centrifugal pump of claim 5, wherein, The backflow channel (13) is a one-way channel in the form of a Tesla valve, which is used to prevent fluid from entering the water storage space (7) through the backflow channel (13).

7. The high head self-priming centrifugal pump of claim 1, wherein, A water injection hole (16) is arranged on the water storage space (7), water is injected into the volute (2) through the water injection hole (16), so that the liquid level is at least submerged in the impeller (10), and the self-priming effect during starting is ensured.

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