Cavitation-resistant mixed-flow pump water inlet device for agricultural irrigation

Abstract

The invention discloses an anti-cavitation mixed-flow pump water inlet device for agricultural irrigation. The anti-cavitation mixed-flow pump water inlet device aims at solving the problem that cavitation is likely to happen to necking-down sections at the lower ends of blades due to high flow speed and low water pressure. The anti-cavitation mixed-flow pump comprises a shell, a rotating shaft is arranged at the upper end of the shell, the rotating shaft is connected with an internal blade, and the lower end of the blade is a necking position; a plurality of compensators are evenly distributed on the circumference of the shell, each compensator comprises a shell, a pressure relief structure and a pressurization structure, the compensators are connected to the necking opening through guide pipes with one-way valves, the pressure relief structures can inject fluid in the compensators into the necking opening at set pressure, and the multiple compensators sequentially work to continuously inject high-pressure fluid. Static pressure is increased by injecting high-pressure fluid into the necking, cavitation can be effectively reduced, and the device is simple and stable in overall structure and can be widely applied to sand-containing environments such as agriculture.

Description

Technical Field

[0001] This article relates to an anti-cavitation mixed flow pump water inlet device for agricultural irrigation. Background Art

[0002] Mixed-flow pumps are widely used in agricultural irrigation because they combine the advantages of both centrifugal and axial-flow pumps. They transport fluids through the centrifugal force and axial thrust generated by rotating blades, making them suitable for medium flow rates and lifts. However, agricultural mixed-flow pumps operate in a harsh environment: The conveying medium often contains sediment, which can easily cause wear on the blades and flow channels. Furthermore, the sudden change in pipe diameter at the constriction below the blades significantly increases the flow rate (according to Bernoulli's principle, increased flow rate leads to decreased static pressure). When the static pressure falls below the saturated vapor pressure of the medium, cavitation occurs. Bubbles generated by liquid vaporization collapse in the high-pressure zone, creating a strong impact that exacerbates blade fatigue and severely shortens the pump's service life.

[0003] Existing solutions for mitigating cavitation primarily include optimizing the flow path at the constriction (e.g., by creating a gradual transition) and increasing inlet pressure. However, these approaches present significant limitations: Flow path optimization is poorly adapted to sandy media, making it susceptible to deformation due to sediment deposition; simply increasing inlet pressure requires additional power and cannot precisely compensate for localized low-pressure areas at the constriction. Some solutions attempt to inject water into the constriction, but these typically operate at constant pressure, failing to generate the sustained high pressure required to effectively increase static pressure. Furthermore, the lack of a filtration mechanism makes it easy for sediment to clog the water injection channel.

[0004] Therefore, there is an urgent need for a mixed flow pump that can accurately provide continuous high-pressure fluid to the necking section and adapt to sandy environments to solve the synergistic problem of cavitation and wear. Summary of the Invention

[0005] The purpose of the present invention is to provide an anti-cavitation mixed flow pump water inlet device for agricultural irrigation, which can reduce the cavitation phenomenon at the necking point by continuous high-pressure injection. The specific structure is as follows:

[0006] An anti-cavitation mixed flow pump water inlet device for agricultural irrigation comprises a housing, wherein the upper end of the housing is provided with a rotating shaft, the bottom of the rotating shaft is connected to a blade, the blade is arranged inside the housing, and the lower end of the blade is a constricted portion;

[0007] Several compensators are evenly distributed along the circumference of the shell. The compensator includes a shell, a pressure relief structure, and a pressurizing structure. A cavity is provided inside the shell. A water inlet and a water outlet are provided at the bottom of the cavity. Both the water inlet and the water outlet are provided with a one-way valve. The water inlet is connected to the constriction through a conduit. A pressure relief structure is provided at the top of the cavity. The pressure relief structure is used to inject the fluid in the cavity into the constriction at a set pressure. The top of the pressure relief structure is connected to the pressurizing structure. The pressurizing structure is used to compensate for the energy released in the pressure relief structure.

[0008] The pressure relief structures and pressure boosting structures of the multiple compensators work in sequence, thereby continuously injecting a certain amount of high-pressure fluid into the neck.

[0009] Furthermore, the pressure relief structure is a spring, and the pressure boosting structure is a motor. This combination of spring and motor can minimize costs. The pressure relief and pressure boosting structures can also be configured as an integrated cylinder structure, and pressure compensation at the constriction can be achieved by extending and retracting the cylinder.

[0010] When the pressure relief structure is a spring and the pressure boosting structure is a motor, the top end of the spring is connected to the inner wall of the housing, and the bottom end of the spring is connected to the piston, and the cross-sectional shape of the piston matches the cavity; the upper surface of the piston is connected to the piston column, and the top of the piston column is connected to the motor through a transmission structure;

[0011] The pressurization process includes the following steps:

[0012] S11, the motor starts, driving the piston rod to move upward, and the piston rod drives the piston to move upward together;

[0013] S12, when the piston moves upward, a certain amount of fluid is sucked into the water inlet, thereby filling the cavity;

[0014] S13, at this time the spring is in a compressed state;

[0015] The decompression process includes the following steps:

[0016] S21, at this time the motor is turned off, and the piston rod and the piston are both in a free state;

[0017] S22. Under the action of the spring, the piston moves downward, squeezing the fluid in the cavity;

[0018] S23. Since one-way valves are provided at both the water inlet and the water outlet, the fluid in the cavity can only be injected into the constriction through the water outlet.

[0019] In order to further protect the compensator and prevent it from being damaged by collision, a protective cover is provided at the bottom of the housing. The protective cover can effectively protect the compensator from being damaged by collision.

[0020] In order to adapt to sandy environments, a filter is installed at the end of the water inlet. The initial filtration of the filter can effectively prevent the mud and sand from damaging the piston, thereby extending the service life of the compensator.

[0021] Preferably, the number of the compensators is 4, and the 4 compensators are evenly distributed at a central angle of 90° along the outer circumference of the shell. This layout can ensure that the high-pressure fluid injected into the neck is more evenly distributed in the circumferential direction, avoid insufficient local pressure compensation, and improve the stability of the anti-cavitation effect.

[0022] Preferably, a flow guide cover is provided at the bottom of the shell, and the flow guide cover is trumpet-shaped, with the large-diameter end facing the outside of the shell to expand the water absorption range, and the small-diameter end smoothly transitions and connects to the bottom of the blade, which can guide the fluid to enter the pump smoothly and reduce turbulent disturbance; a filter net is provided in the flow guide cover, which can pre-intercept large particles of impurities such as weeds and stones in the water, providing the first line of protection for the blades.

[0023] Preferably, the upper end of the compensator is connected to the outer surface of the shell through a flange.

[0024] Preferably, the minimum diameter of the constriction is 0.4-0.7 of the maximum diameter of the entire mixed flow pump. This can meet the flow rate requirements of the medium while avoiding excessive flow rate and pressure drop caused by too narrow a constriction, thus achieving a balance between flow rate and anti-cavitation performance.

[0025] Preferably, the surface of the blade is provided with a high-strength metal coating with uniform thickness and firmly bonded to the substrate, which can significantly improve the hardness and wear resistance of the blade surface, resist the erosion and wear of sand-laden water flow, and extend the service life of the blade.

[0026] Preferably, the filter screen is a 100-200 mesh metal screen, and the interior of the filter is filled with filter cloth.

[0027] Beneficial effects:

[0028] This invention addresses the problem of cavitation at the constriction at the lower end of mixed-flow pump blades, which is prone to cavitation due to high flow velocity and low static pressure. By installing multiple compensators around the circumference of the casing and leveraging a pressure-relieving structure with a pressure-boosting structure, high-pressure water is continuously injected upstream of the constriction. This design not only reduces the risk of cavitation by increasing the effective flow rate across the flow cross-section, but also utilizes the downward pressure of the pressure-relieving structure to increase the pressure of the injected fluid, raising the static pressure at the constriction from below the saturated vapor pressure to above it, thereby preventing liquid vaporization and reducing the occurrence of cavitation.

[0029] At the same time, the rotation of multiple compensators ensures the continuity of high-pressure water injection. The structure is simple and stable, which can adapt to harsh environments such as sand, and effectively improves the working stability and service life of the mixed flow pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of an anti-cavitation mixed flow pump water inlet device used for agricultural irrigation;

[0031] Figure 2This is a schematic diagram of the bottom structure of an anti-cavitation mixed flow pump water inlet device used for agricultural irrigation;

[0032] Figure 3 It is a structural diagram of the water suction part of the mixed flow pump;

[0033] Figure 4 It is a cross-sectional schematic diagram of a water inlet device of an anti-cavitation mixed flow pump used for agricultural irrigation;

[0034] Figure 5 yes Figure 4 A magnified view of the partial layout;

[0035] 1. Housing, 2. Protective cover, 3. Compensator, 31. Cavity, 32. Piston rod, 33. One-way valve, 34. Conduit, 35. Spring, 4. Motor, 5. Flow guide cover, 6. Filter, 7. Filter. DETAILED DESCRIPTION

[0036] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0037] Example 1: A cavitation-resistant mixed-flow pump inlet device for agricultural irrigation includes a housing 1 with a protective cover 2 at its lower end. A rotating shaft extends through the housing 1, its lower end extending into the interior of the housing 1 and fixedly connected to blades. A constriction is formed at the lower end of the blades. Due to the sudden change in pipe diameter at the constriction, the flow rate increases significantly, the water pressure drops significantly, and this region is highly susceptible to cavitation.

[0038] Four compensators 3 are evenly distributed along the circumference of the housing 1, and each compensator 3 is equipped with a motor 4. The motor 4 drives the piston rod 32 upward through a gear transmission mechanism. The lower end of the piston rod 32 is firmly connected to the piston, and the piston forms a sealed fit with the cavity inside the compensator 3.

[0039] The protective cover 2 at the bottom of the housing 1 not only protects the four compensators 3 but also reduces interference from external debris on their operation. A filter 7 is installed at the bottom of the compensators 3. The water to be pumped, after being filtered to remove impurities such as silt, enters the cavity of the compensators 3 through the water inlet. Furthermore, a flow deflector is installed at the bottom of the mixed-flow pump body. This deflector contains a filter screen that effectively blocks silt and large particles from being drawn into the pump, preventing damage to the blades caused by the impact of impurities.

[0040] During operation, the four compensators 3 alternately enter the pressure relief phase in a clockwise order. When one compensator is in the pressure relief phase, its internal spring resets, pushing the piston downward, pressurizing the fluid in the cavity and injecting it into the constricted section through the conduit 34. Simultaneously, the other compensators enter the pressure boost phase. The motor drives the piston rod 32 upward, compressing the spring to store energy, and the cavity draws in filtered fluid through the water inlet, completing the charging process. Once the currently decompressed compensator has completed its pressure boost, the other compensators rotate to their respective operating states.

[0041] Through this cyclic alternating working mode, it is possible to ensure that high-pressure fluid is continuously injected into the necking point, so that the static pressure of the necking section is effectively increased and always higher than the saturated vapor pressure of water at that temperature, thereby fundamentally suppressing the occurrence of cavitation and ensuring the stable operation of the mixed flow pump in sandy environments such as agricultural irrigation.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An anti-cavitation mixed flow pump water inlet device for agricultural irrigation, characterized in that: The invention comprises a shell, wherein the upper end of the shell is provided with a rotating shaft, the bottom of the rotating shaft is connected to the blade, the blade is arranged inside the shell, and the lower end of the blade is a constricted portion; Several compensators are evenly distributed along the circumference of the shell. The compensator includes a shell, a pressure relief structure, and a pressurizing structure. A cavity is provided inside the shell. A water inlet and a water outlet are provided at the bottom of the cavity. Both the water inlet and the water outlet are provided with a one-way valve. The water inlet is connected to the constriction through a conduit. A pressure relief structure is provided at the top of the cavity. The pressure relief structure is used to inject the fluid in the cavity into the constriction at a set pressure. The top of the pressure relief structure is connected to the pressurizing structure. The pressurizing structure is used to compensate for the energy released in the pressure relief structure. The pressure relief structures and pressure boosting structures of the multiple compensators work in sequence, thereby continuously injecting a certain amount of high-pressure fluid into the neck.

2. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 1, characterized in that , the pressure relief structure is a spring, and the pressure boosting structure is a motor; The top end of the spring is connected to the inner wall of the housing, and the bottom end of the spring is connected to the piston, the cross-sectional shape of the piston matches the cavity; the upper surface of the piston is connected to the piston column, and the top of the piston column is connected to the motor through a transmission structure; The pressurization process includes the following steps: S11, the motor starts, driving the piston rod to move upward, and the piston rod drives the piston to move upward together; S12, when the piston moves upward, a certain amount of fluid is sucked into the water inlet, thereby filling the cavity; S13, at this time the spring is in a compressed state; The decompression process includes the following steps: S21, at this time the motor is turned off, and the piston rod and the piston are both in a free state; S22. Under the action of the spring, the piston moves downward, squeezing the fluid in the cavity; S23. Since one-way valves are provided at both the water inlet and the water outlet, the fluid in the cavity can only be injected into the constriction through the water outlet.

3. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 1, characterized in that , a protective cover is provided at the bottom of the shell.

4. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 1, characterized in that , a filter is provided at the end of the water inlet.

5. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to any one of claims 1 to 4, characterized in that , the number of compensators is 4.

6. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 5, characterized in that A flow guide cover is provided at the bottom of the shell. The flow guide cover is in the shape of a trumpet, with its large-diameter end facing the outside of the shell and the small-diameter end connected to the bottom of the blade. A filter screen is provided inside the flow guide cover.

7. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 6, characterized in that The upper end of the compensator is connected to the outer surface of the shell through a flange.

8. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 6, characterized in that The minimum diameter of the necking is 0.4-0.7 of the maximum diameter of the overall mixed flow pump.

9. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 6, characterized in that ,The surface of the blade is provided with a high-strength metal coating.

10. The anti-cavitation mixed flow pump water inlet device for agricultural irrigation according to claim 6, characterized in that ,The filter mesh is a 100-200 mesh metal mesh, and the inside of the filter is filled with filter cloth.

Images