Negative pressure backflow type multi-stage sealing lifting column, buried irrigation system

Abstract

This utility model belongs to the field of agricultural irrigation technology and discloses a negative pressure backflow type multi-stage sealed lifting column and a buried irrigation system. The lifting column includes an outer sleeve, a middle sleeve, and an inner sleeve that are sequentially nested together. The bottom end of the outer sleeve is fixed with a connecting seat, and the top end is fixed with a first top sealing ring and a second top sealing ring. The top end of the inner sleeve is fixed with a nozzle, and the bottom end is fixed with a first bottom sealing element. The first bottom sealing element has a through hole, and a sealing plug is movably installed at the through hole. The top end of the middle sleeve is fixed with a third top sealing ring, and the bottom end is fixed with a second bottom sealing element. The buried irrigation system includes a pipe network and a water pump. The above-mentioned lifting column is installed on the pipe network, and a negative pressure generating device and a negative pressure detection alarm device are also provided. This utility model has good telescopic effect, low failure rate, simple construction, low maintenance cost, and long service life, and is suitable for farmland irrigation.

Description

Technical Field

[0001] This utility model belongs to the field of agricultural irrigation technology, and relates to a negative pressure back-pulling multi-stage sealing lifting column, as well as a buried irrigation system. Background Technology

[0002] In recent years, with the shift from small-scale single-household farming to large-scale field cultivation, and the gradual decrease in the number of people engaged in agricultural labor, sprinkler irrigation, which offers better water-saving effects, has been increasingly popular. To reduce the impact of sprinkler poles on agricultural equipment, telescopic pole structures have emerged. These poles are pushed out by water pressure. Currently, there are two main types of pole retraction: one is the spring-loaded type, where the spring automatically retracts the pole after water is stopped; its disadvantage is a high failure rate. The other is the water pressure-reset type, which requires a separate water return pressure system, has high construction costs, can only accommodate two levels of telescopic poles, requires deep burial, has high construction costs, and is difficult to maintain. Besides the above types, the authorized announcement number CN218244896U, entitled "A Rising Column for Sandy Land Irrigation," is also relevant. A Chinese utility model patent discloses a structure that uses atmospheric pressure to retract a telescopic rod. However, its sealing structure is located on the top of the telescopic rod. As the telescopic rod rises or falls, sand and soil can easily intrude when it descends because there is no seal at the top. Although a sand-draining structure is provided when the telescopic rod extends, the time between irrigation and the next irrigation is long, causing sand and soil to clump together and accumulate. During the next irrigation, the water cannot completely drain the sand and soil. After prolonged use, the sand and soil accumulation worsens, the sand-draining effect weakens, the telescopic rod becomes stuck when extending, the extension height decreases, and it cannot retract completely, which seriously affects agricultural operations. Utility Model Content

[0003] To address the shortcomings of existing technologies, this utility model aims to provide a negative pressure retraction type multi-stage sealing lifting column, which achieves the goals of being unaffected by sand and soil during expansion and contraction, having a good retraction effect, being durable, and having low maintenance costs.

[0004] This utility model also provides an irrigation system that achieves a high degree of automation, long service life, and low maintenance cost.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A negative pressure back-extraction type multi-stage sealing lifting column

[0007] It includes an outer sleeve, a middle sleeve, and an inner sleeve that are connected in sequence. There are N middle sleeves, where N ≥ 0 and is an integer.

[0008] The outer sleeve has a connecting seat fixed at its bottom end and a first top sealing ring for blocking sand and soil and a second top sealing ring for sealing during negative pressure backflow and irrigation. The first top sealing ring is located above the second top sealing ring. The inner sleeve has a nozzle fixed at its top end and a first bottom sealing element fixed at its bottom end. The first bottom sealing element has a through hole for water to pass through, and a sealing plug is movably installed at the through hole. When water flows through, the sealing plug is pushed up, and when negative pressure backflow occurs, the sealing plug falls into the through hole to seal the gas. The middle sleeve has a third top sealing ring fixed at its top end and a second bottom sealing element fixed at its bottom end.

[0009] When N=0, during negative pressure retraction, the top ends of the inner sleeve and outer sleeve are sealed by the first top sealing ring and the second top sealing ring. After the inner sleeve is reset, the first bottom sealing element makes sealing contact with the inner wall of the connecting seat.

[0010] When N≥1, during negative pressure retraction, the outer sleeve and the middle sleeve are sealed by the first top sealing ring and the second top sealing ring, and the adjacent outer sleeves and the outer sleeve and the inner sleeve are sealed by the third top sealing ring. After the inner sleeve and the middle sleeve are reset, the first bottom sealing element, the second bottom sealing element and the inner wall of the connecting seat are sealed in sequence.

[0011] As a limitation of this utility model, the first top sealing ring and the third top sealing ring have the same structure, both including an outer ring and an inner ring fixed on the outer ring, with the top and bottom ends of the inner ring fastened toward its center.

[0012] As a further limitation of this utility model, a flange seat is fixedly provided on the outer wall of the outer sleeve, and a flange is detachably provided on the flange seat. The inner wall of the flange is fixedly connected to the outer wall of the inner ring of the first top sealing ring, and the flange presses the first top sealing ring and the second top sealing ring into the inner cavity of the flange seat for fixation.

[0013] As a further limitation of this utility model, the lip of the second top sealing ring is positioned facing the ground surface, and the second top sealing ring is fixedly connected to the first top sealing ring.

[0014] As another limitation of this utility model, the sealing plug is spherical and its density is greater than that of water, and the first bottom sealing member is provided with a crossbar to prevent the sealing plug from rising.

[0015] As a limitation of this utility model, any two of the first bottom end seal, the second bottom end seal, and the connecting seat are fitted by a conical surface.

[0016] As a third limitation of this utility model, sealing gaskets are fixed on the outer walls of both the first bottom sealing member and the second bottom sealing member.

[0017] A buried irrigation system includes a pipe network buried below the ground surface and a water pump for pumping water. The pipe network is provided with the aforementioned negative pressure backflow type multi-stage sealed lifting columns at intervals. The lifting columns are fixed to the pipe network by connecting seats. A negative pressure generating device is connected to the pipe network, and a negative pressure detection alarm device is also fixedly installed.

[0018] By adopting the above-mentioned technical solution, the beneficial effects achieved by this utility model compared with the prior art are as follows:

[0019] (1) This utility model forms a sealed structure for the entire cavity by the cooperation of the first top sealing ring and the sealing plug. It uses negative pressure to reset each level of the sleeve. The suction force of the negative pressure ensures that the reset of each level of the sleeve is accurate. At the same time, it adopts a multi-level sealing combination of upper sealing ring sealing and lower conical surface sealing, gas sealing and sand sealing, etc., to ensure that the cavity is tightly sealed and effectively prevent sand from entering the pipe body. After long-term use, as long as the negative pressure is sufficient, its extended height can reach 95% to 100% of the maximum extended height. It can also be set with a multi-section structure to achieve short telescopic poles, shallow burial, low construction cost, and convenient installation and maintenance.

[0020] (2) The inner ring of the first top sealing ring of this utility model snaps towards the center and hugs the outer wall of the sleeve under the action of negative pressure, further increasing the sealing of the cavity, preventing sand and soil from entering, and improving the accuracy of the sleeve falling back.

[0021] (3) The present invention provides a flange on the outer sleeve, and the flange is fixed to the inner ring of the first top sealing ring to ensure that the first top sealing ring will not deform when negative pressure is generated. Furthermore, the flange can be removed so that the inner core inside the outer sleeve can be taken out for repair or replacement, saving time and effort and greatly reducing maintenance costs. At the same time, the flange and the flange seat are detachably connected, forming a weak link. When the intermediate sleeve or inner sleeve tends to separate from the outer sleeve due to excessive water pressure or excessive negative pressure, the flange will be damaged first, and the outer sleeve will not be damaged. Since the outer sleeve is buried underground and connected to the pipe network, it is not easy to replace. This structure can eliminate hidden dangers, increase the service life of the outer sleeve, and reduce maintenance costs.

[0022] (4) The lip of the second top sealing ring of this utility model faces upward, so that the lip edge is tightly attached to the outer wall of the sleeve under negative pressure, resulting in a better sealing effect;

[0023] (5) The sealing plug of this utility model is spherical, which has a better sealing effect with the through hole of the first bottom sealing element. Its density is greater than that of water, which can prevent the water at a higher level after irrigation stops from pushing it upward, thus ensuring the sealing effect. At the same time, the crossbar can prevent the sealing plug from being lifted too high by the water, ensuring that the sealing plug is reset in time after the water stops.

[0024] (6) The bottom sealing element of this utility model adopts a conical surface seal, which improves the sealing effect while reducing the space occupied, and the sealing gasket further improves the sealing effect;

[0025] (7) The irrigation system of this utility model has a high degree of automation. It can automatically alarm through the negative pressure detection alarm device, and can promptly investigate the damaged parts. The multi-stage sleeve cooperates with expansion and contraction to reduce the burial depth. It is simple to construct, has low maintenance costs, and has a long service life.

[0026] In summary, this utility model has good telescopic effect, low failure rate, simple construction, low maintenance cost, and long service life, making it suitable for farmland irrigation. Attached Figure Description

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1 This is a schematic cross-sectional view of the inner sleeve after it falls into the outer sleeve in Embodiment 1 of this utility model.

[0029] Figure 2 This is a schematic cross-sectional view of the inner sleeve extending out of the outer sleeve in Embodiment 1 of this utility model;

[0030] Figure 3 This is a cross-sectional structural diagram of the first top sealing ring in Embodiment 1 of this utility model;

[0031] Figure 4 This is a cross-sectional structural diagram of the second top sealing ring in Embodiment 1 of this utility model;

[0032] Figure 5 This is a schematic cross-sectional view of the inner sleeve and intermediate sleeve after they fall into the outer sleeve in Embodiment 2 of this utility model.

[0033] Figure 6 This is a schematic cross-sectional view of the inner sleeve and two intermediate sleeves after they fall into the outer sleeve in Embodiment 3 of this utility model.

[0034] Figure 7 This is a structural schematic diagram of Embodiment 4 of the present invention.

[0035] In the diagram: 1. Outer sleeve; 2. Inner sleeve; 3. Connecting seat; 4. First top sealing ring; 41. Outer ring; 42. Inner ring; 5. Second top sealing ring; 51. Lip; 6. Flange seat; 7. Flange; 8. Nozzle; 9. First bottom sealing element; 91. Through hole; 10. Sealing plug; 11. Crossbar; 12. Sealing gasket; 13. Intermediate sleeve; 14. Third top sealing ring; 15. Fixing ring; 16. Second bottom sealing element; 17. Water pump; 18. Hydraulic vacuum pump; 19. Solenoid valve; 20. Negative pressure detection alarm device; 21. Lifting column. Detailed Implementation

[0036] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0037] Example 1: A negative pressure retraction type multi-stage sealing lifting column

[0038] like Figure 1 , Figure 2 As shown, this embodiment includes an outer sleeve 1 and an inner sleeve 2 that are sequentially fitted together, and also includes a connecting seat 3 for fixed connection with the pipeline network. The outer sleeve 1 is fixed on the connecting seat 3, and the inner sleeve 2 is inserted into the outer sleeve 1 and can move up and down along the outer sleeve 1. The above is the prior art. The improvement of this application is that through multi-stage sealing, the cavity of the lifting column is sealed, and the inner sleeve 2 is reset by using negative pressure, ensuring that the inner sleeve 2 can reach the maximum extension length when it rises and can descend to the initial position after retraction. At the same time, it prevents sand and soil from entering and extends the service life. The upper end of the outer sleeve 1 is provided with a first top sealing ring 4 to seal the upper end of the cavity between the outer sleeve 1 and the inner sleeve 2, and the lower end of the inner sleeve 2 is provided with a first bottom sealing member 9 to seal the lower end of the cavity between the outer sleeve 1 and the inner sleeve 2. A sealing plug 10 is provided on the first bottom sealing member 9 to seal the inner cavity of the inner sleeve 2. This will be described in detail below.

[0039] The upper end of connector 3 ( Figure 1 (upper end) and lower end ( Figure 1 The lower end of each tube is cylindrical, with a tapered transition in the middle. The outer sleeve 1 is inserted into the cylinder at the upper end of the connecting seat 3, and the cylinder at the lower end of the connecting seat 3 is fixedly connected to the pipeline.

[0040] like Figure 3 , Figure 4 As shown, the first top sealing ring 4 includes an outer ring 41 and an inner ring 42 fixed to the inner wall of the outer ring 41. The height of the inner ring 42 is greater than the height of the outer ring 41, so that both ends of the inner ring 42 are separated from the outer ring 41, and the top and bottom ends of the inner ring 42 are fastened to its center. The inner wall of the second top sealing ring 5 is fixed with an inwardly opening lip 51.

[0041] Both the first and second top sealing rings 4 and 5 are fixed to the top of the outer sleeve 1 and fit against the outer wall of the inner sleeve 2. The first top sealing ring 4 prevents sand from entering the cavity between the outer sleeve 1 and the inner sleeve 2. Since the outer sleeve 1 needs to be buried below the ground surface, its top is in contact with sand. The first top sealing ring 4 effectively prevents sand from entering the cavity and affecting the accuracy of the inner sleeve 2's repositioning. In this embodiment, the second top sealing ring 5 is used to seal gas during negative pressure backflow and to seal water during irrigation, allowing water to be sprayed from the nozzle 8.

[0042] A flange seat 6 is fixed to one end of the outer sleeve 1 that is not connected to the connecting seat 3. A flange 7 is detachably mounted on the flange seat 6, and the flange 7 is relatively thin. The outer wall of the inner ring 42 of the first top sealing ring 4 is glued to the inner wall of the flange 7. This glued part is the part of the inner ring 42 that is not connected to the outer ring 41. At the same time, the end face of the outer ring 41 of the first top sealing ring 4 is glued to the bottom surface of the flange 7. The second top sealing ring 5 is located below the first top sealing ring 4. Figure 1 Below), above the second top sealing ring 5 ( Figure 1 (above) and below the first top sealing ring 4 ( Figure 1 The bottom part of the second top sealing ring 5 is fixed with glue. Figure 1 The bottom of the second top sealing ring 5 rests against the top of the outer tube 1, with the lip of the second top sealing ring 5 facing upwards. Figure 1 (The upward-facing part) is set. During installation, the flange 7 is connected to the flange seat 6 with self-tapping screws, so that the flange 7 presses the first top sealing ring 4 and the second top sealing ring 5 into the inner cavity of the flange seat 6. Since the flange 7 and the flange seat 6 are detachably connected by self-tapping screws, when the irrigation water pressure is too high, the back pressure is too high, the inner sleeve 2 is damaged and pulled out by the rotary tiller due to insufficient installation depth, or the inner sleeve 2 is damaged and pulled out by the rotary tiller due to damage to the first top sealing ring 4, etc., the inner sleeve 2 tends to separate from the outer sleeve 1. The screws are pulled out or the flange 7 is damaged first because the flange 7 is thin. This will not damage the outer sleeve 1 and the flange seat 6, thus increasing the service life of the outer sleeve 1. Since the outer sleeve 1 is buried below the ground and connected to the pipeline network, it is not easy to replace. This structure can eliminate hidden dangers and reduce maintenance costs. Since the inner wall of flange 7 is fixedly connected to the outer ring 41 of the first top sealing ring 4, when the negative pressure is large, the first top sealing ring 4 will not deform and leak air, thus improving the sealing performance. It can block sand and soil, effectively preventing sand and soil from entering the cavity between the inner sleeve 2 and the outer sleeve 1. Furthermore, the lip of the second top sealing ring 5 faces upward, and under the action of negative pressure, its lip 51 is tightly attached to the inner sleeve 2, resulting in a better sealing effect.

[0043] A nozzle 8 is fixedly mounted at the top of the inner sleeve 2, and a first bottom seal 9 is fixedly mounted at the bottom. One end of the first bottom seal 9 is cylindrical and is inserted and fixed to the inner wall of the inner sleeve 2. Two crossbars 11 are fixed at the port of this end. The other end of the first bottom seal 9 is conical, with both its inner and outer walls being conical. The taper of the outer wall is the same as the taper of the inner wall of the connecting seat 3. After the lifting column is reset, the first bottom seal 9 is in sealing contact with the inner wall of the connecting seat 3. A sealing gasket 12 is fitted on the outer wall of the first bottom seal 9 to make the outer wall of the first bottom seal 9 seal more tightly with the inner wall of the connecting seat 3. The inner wall of the first bottom seal 9 has a conical opening to form a through hole 91 for water passage. A sealing plug 10 is movably installed at the through hole 91. The sealing plug 10 is spherical and its density is greater than that of water. When water passes through, the sealing plug 10 is lifted to pass through the water and blocked by the crossbar 11 to prevent it from rising too high. When the negative pressure is pulled back, the sealing plug 10 falls into the through hole 91 and seals the gas by contacting the conical surface. The sealing plug 10 is movable up and down, which can realize automatic opening and closing. The structure is simple and the design is ingenious.

[0044] During negative pressure backflow, the top ends of the inner sleeve 2 and outer sleeve 1 are sealed by the first top sealing ring 4 and the second top sealing ring 5, while the bottom ends are sealed by the first bottom sealing element 9 and the connecting seat 3. The sealing plug 10 rests in the through hole of the first bottom sealing element 9, sealing the inner cavity of the inner sleeve 2. Specifically, after the water pressure is lost, the sealing plug 10 rests in the through hole 91 of the first bottom sealing element 9, tightly blocking the through hole 91 under the suction of negative pressure, sealing the inner sleeve 2. Simultaneously, the outer ring 41 of the first top sealing ring 4 on the outer sleeve 1 adheres tightly to the inner sleeve 2, and the lip 51 of the second top sealing ring 5 adheres tightly to the inner sleeve, sealing the cavity between the outer sleeve 1 and the inner sleeve. Under the multi-stage sealing action, the negative pressure causes the inner sleeve 2 to reset. Because the top sealing rings remain stationary while the inner sleeve 2 moves up and down, no gaps are created that allow sand to intrude. The first top sealing ring 4 and the second top sealing ring 5 provide double protection against both gas and sand, further enhancing the sealing effect.

[0045] Example 2: A negative pressure retraction type multi-stage sealing lifting column

[0046] like Figure 5 As shown, the structure of this embodiment is basically the same as that of embodiment 1. The difference is that an intermediate sleeve 13 is provided between the inner sleeve 2 and the outer sleeve 1 in this embodiment, which will be described in detail below.

[0047] The intermediate sleeve 13 is inserted between the inner sleeve 2 and the outer sleeve 1. A third top sealing ring 14 is fixed at the top end of the intermediate sleeve 13, and a second bottom sealing element 16 is fixed at the bottom end. The structure of the third top sealing ring 14 is the same as that of the second top sealing ring 5, but its installation method is different from that of the first top sealing ring 4. In this embodiment, the third top sealing ring 14 is used to seal the gas during negative pressure backflow. In order to ensure that the third top sealing ring 14 does not deform under negative pressure, a fixing ring 15 is glued to the inner wall of the intermediate sleeve 13. A groove is formed on the inner wall of the fixing ring 15. During installation, the outer ring 41 of the third top sealing ring 14 is glued to the groove of the fixing ring 15. At the same time, the inner wall above the groove of the fixing ring 15 is glued to the outer ring 41 of the third top sealing ring 14, ensuring that the upper and lower ends of the inner ring 42 of the third top sealing ring 14 are tightly attached to the outer wall of the inner sleeve 2 under negative pressure, while the middle position of the outer ring 41 does not deform.

[0048] The upper end of the second bottom seal 16 is cylindrical and is used to be inserted into the inner wall of the intermediate sleeve 13 for fixation. The lower end of the second bottom seal 16 is frustoconical, so that its outer wall forms a conical surface for sealing contact with the conical surface of the connecting seat 3. The inner wall of the second bottom seal 16 is conical and is used to seal contact with the outer wall of the first bottom seal 9. A sealing gasket 12 is fitted on the outer wall of the second bottom seal 16 to increase the sealing effect between the second bottom seal 16 and the connecting seat 3.

[0049] The sealing principle of this embodiment is the same as that of embodiment 1. When in use, the inner sleeve 2 rises and drives the middle sleeve 13 to rise until the second bottom sealing member 16 on the middle sleeve 13 abuts against the second top sealing ring 5 on the outer sleeve 1.

[0050] Example 3: A negative pressure retraction type multi-stage sealing lifting column

[0051] like Figure 6 As shown, the structure of this embodiment is basically the same as that of embodiment 2. The difference is that this embodiment has two intermediate sleeves 13 between the inner sleeve 2 and the outer sleeve 1, which will be described in detail below.

[0052] The top ends of the two intermediate sleeves 13 are each provided with a third top sealing ring 14, and the bottom ends are each fixed with a second bottom sealing element 16. The third top sealing ring 14 and the second bottom sealing element 16 are the same as the installation structure in Embodiment 2. When sealing the bottom end, the first bottom sealing element 9, the two second bottom sealing elements 16, and the connecting seat 3 are in sequential conical surface sealing contact.

[0053] Example 4: A buried irrigation system

[0054] like Figure 7As shown, this embodiment includes a pipe network buried underground and a water pump 17 for pumping water. The pipe network is intermittently equipped with negative pressure backflow type multi-stage sealed lifting columns as described in Embodiment 2. The lifting columns 21 are fixed to the pipe network via connecting seats 3, and the outer casing 1 of the lifting columns 21 is buried underground. The pipe network includes main pipelines and branch pipelines. Each branch pipeline is equipped with a solenoid valve 19. By controlling the opening and closing of the solenoid valves 19, zonal irrigation control or overall irrigation can be selected.

[0055] A negative pressure generating device is installed in the pipeline network. The negative pressure generating device is a hydraulic vacuum pump 18 or a water storage tank installed at a high elevation. The water in the storage tank enters the pipeline network by utilizing the elevation difference, thereby discharging the water stored in the main pipeline and creating negative pressure. In this embodiment, a hydraulic vacuum pump 18 is used. The hydraulic vacuum pump 18 is installed in parallel on the main pipeline, and a solenoid valve 19 is installed on the parallel pipeline. When the water pump 17 is turned on, the negative pressure generating device is turned off, and when the negative pressure generating device is turned on, the water pump 17 is turned off.

[0056] In this embodiment, a negative pressure detection alarm device 20 is also fixedly installed on the pipeline. When the negative pressure value in the pipeline is detected to be less than the set value, an alarm is triggered to remind the staff to check for leaks or faults. The check can be performed by controlling the on / off state of the solenoid valve 19.

[0057] When using this embodiment, the lifting column 21 is connected to the pipeline. When irrigating, the water pump 17 is turned on. Since the first bottom seal 9 and the outer wall of the connecting seat 3 are sealed by the conical surface and the sealing gasket 12 in the initial state, under the action of water pressure, the water first pushes open the sealing plug 10 and enters the inner sleeve 2, lifting the inner sleeve 2. The inner sleeve 2 carries the first bottom seal 9 up. When it rises to the position where the first bottom seal 9 and the second top seal ring 5 abut, it drives the middle sleeve 13 to continue to rise. When the middle sleeve 13 rises to the position where the second bottom seal 16 and the second top seal ring 5 abut, it stops rising and continues to irrigate. After irrigation is completed and water pressure is lost, the sealing plug 10 falls into the through hole 91 of the first bottom sealing member 9, and the negative pressure generating device is activated. Under the action of negative pressure, the inner sleeve 2 and the intermediate sleeve 13 fall down in sequence until the outer wall of the first bottom sealing member 9 contacts the inner wall of the second bottom sealing member 16, and the outer wall of the second bottom sealing member 16 contacts the inner wall of the connecting seat 3. The inner sleeve 2 and the intermediate sleeve 13 are then reset.

[0058] It should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A negative pressure retraction type multi-stage sealing lifting column, characterized in that: It includes an outer sleeve, a middle sleeve, and an inner sleeve that are connected in sequence. There are N middle sleeves, where N ≥ 0 and is an integer. The outer sleeve has a connecting seat fixed at its bottom end and a first top sealing ring for blocking sand and soil and a second top sealing ring for sealing during negative pressure backflow and irrigation. The first top sealing ring is located above the second top sealing ring. The inner sleeve has a nozzle fixed at its top end and a first bottom sealing element fixed at its bottom end. The first bottom sealing element has a through hole for water to pass through, and a sealing plug is movably installed at the through hole. When water flows through, the sealing plug is pushed up, and when negative pressure backflow occurs, the sealing plug falls into the through hole to seal the gas. The middle sleeve has a third top sealing ring fixed at its top end and a second bottom sealing element fixed at its bottom end. When N=0, during negative pressure retraction, the top ends of the inner sleeve and outer sleeve are sealed by the first top sealing ring and the second top sealing ring. After the inner sleeve is reset, the first bottom sealing element makes sealing contact with the inner wall of the connecting seat. When N≥1, during negative pressure retraction, the outer sleeve and the middle sleeve are sealed by the first top sealing ring and the second top sealing ring, and the adjacent outer sleeves and the outer sleeve and the inner sleeve are sealed by the third top sealing ring. After the inner sleeve and the middle sleeve are reset, the first bottom sealing element, the second bottom sealing element and the inner wall of the connecting seat are sealed in sequence.

2. The negative pressure retraction type multi-stage sealing lifting column according to claim 1, characterized in that: The first and third top sealing rings have the same structure, both including an outer ring and an inner ring fixed on the outer ring, with the top and bottom ends of the inner ring fastened toward its center.

3. The negative pressure retraction type multi-stage sealing lifting column according to claim 2, characterized in that: A flange seat is fixedly provided on the outer wall of the outer sleeve, and a flange is detachably provided on the flange seat. The inner wall of the flange is fixedly connected to the outer wall of the inner ring of the first top sealing ring. The flange presses the first top sealing ring and the second top sealing ring into the inner cavity of the flange seat for fixation.

4. The negative pressure retraction type multi-stage sealing lifting column according to claim 3, characterized in that: The lip of the second top sealing ring is positioned facing the ground surface, and the second top sealing ring is fixedly connected to the first top sealing ring.

5. The negative pressure retraction type multi-stage sealing lifting column according to any one of claims 1-4, characterized in that: The sealing plug is spherical and its density is greater than that of water. The first bottom sealing element is provided with a crossbar to prevent the sealing plug from rising.

6. The negative pressure retraction type multi-stage sealing lifting column according to claim 5, characterized in that: Any two of the first bottom end seal, the second bottom end seal, and the connecting seat are fitted with a conical surface.

7. The negative pressure retraction type multi-stage sealing lifting column according to any one of claims 1-4 and 6, characterized in that: A sealing gasket is fixed on the outer wall of both the first bottom sealing member and the second bottom sealing member.

8. A buried irrigation system, characterized in that: It includes a pipe network buried underground and a water pump for pumping water. The pipe network is provided with negative pressure back-pulling multi-stage sealing lifting columns as described in any one of claims 1-7 at intervals. The lifting columns are fixed to the pipe network by connecting seats. A negative pressure generating device is connected to the pipe network, and a negative pressure detection alarm device is also fixedly installed.

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