Full-automatic maintenance-free check valve

Abstract

The utility model discloses a full-automatic maintenance-free check valve which is provided with a valve ball, a valve body and a valve seat, a liquid inlet and a liquid outlet are formed in the valve body, the valve ball, the valve seat and a pressure sensor are all installed in a ball cage provided with a flow guide groove, the ball cage is installed in the valve body, and the flow guide groove is communicated with the valve body. The sealing box, the gland, the ball cage seat and the valve body are sequentially connected, the servo motor is fixed on the sealing box provided with the sealing element, and the cleaning and dredging shaft with the paddle at the lower end penetrates through the ball cage seat, the gland and the sealing box to be connected with the servo motor; the servo motor is connected with a PLC in an electrical control cabinet through a cable, and the pressure sensor is in wireless connection with the PLC. According to the check valve, reverse flowing of liquid is limited, normal use of the check valve can be guaranteed without cleaning and maintenance, the check valve is reasonable in overall structural design, the working period of cleaning operation is more reasonable, quick-wear parts are convenient to disassemble and replace, and the conveying efficiency of a conveying pipeline and a conveying process is improved.

Description

Technical Field

[0001] The utility model relates to a check valve for limiting reverse flow of liquid in oil and gas production, gathering and transportation and industrial production, in particular to a full-automatic maintenance-free check valve. Background Art

[0002] Check valves are widely installed in various pipelines and pipe network processes in the industrial and petroleum industries. Their function is to ensure that liquids can only flow in one direction. At the same time, when the equipment installed with them is shut down or suspended, it can prevent production accidents caused by reverse flow of liquid.

[0003] Since the check valve is installed on the pipeline and process, the working environment of the internal components of the check valve is complex, especially the check valve installed in the oil and gas transmission pipeline, water injection pipeline and process in the oil and gas industry, which is always in the fluid with complex components such as high oil content, high mineralization, mud, various chemical agents, etc., which is easy to cause corrosion, blockage, leakage and other failure phenomena of the check valve, requiring staff to perform maintenance from time to time. The check valve currently widely used in oil and water wells, oil and gas gathering pipelines and processes is mainly composed of valve body, valve ball, valve seat and plug, etc. It has a simple structure, is easy to use, and the valve is detachable.

[0004] However, this type of check valve has the following disadvantages: Due to the harsh working environment of the valves in the oil and gas pipelines and processes, in order to ensure that the check valve does not fail, it is necessary to clean and maintain the valve ball, valve seat and other components in time to ensure that it works properly. However, if the staff does not perform maintenance on a regular basis, it will consume a lot of working time and affect work efficiency.

[0005] During the maintenance of the check valve, it is usually carried out by letting the fluid in the pipeline and process go through the bypass valve or shutting down the equipment installed with the check valve. The most common operation method is: A. Stop the medium delivery and drain the medium; B. Remove the plug and take out the valve ball, and clean the valve ball; C. Then flush the valve seat; D. After cleaning, put the valve ball in and plug the plug.

[0006] The entire maintenance operation process is long and the procedures are complicated, which reduces the opening rate of oil and water wells and increases production costs.

[0007] Since the check valve often works under pressure, maintenance and disassembly of the check valve may cause the conveying medium in the pipeline and process to overflow. Improper protection may cause pollution to the environment and harm the health of the workers.

[0008] The check valve currently used not only increases the workload of workers, but also pollutes the environment, causes harm to the health of employees, and reduces the benefits of enterprises.

[0009] After searching, there are currently the following related one-flow valves: Patent application number CN201420541925.2 discloses a one-flow valve, which includes a shell, a valve seat, a valve cover and a valve ball; the shell is a three-way valve body; the valve seat is arranged at the lower end of the shell, and is threadedly connected to the shell; the valve cover is threadedly connected to the valve seat; the valve ball is arranged in the space formed between the valve seat and the valve cover. The valve seat has a center hole, the valve ball is located in the center hole, and the inner surface of the center hole is a conical arc surface. The above utility model can realize the non-fire maintenance check valve, which greatly reduces the well shutdown time; it has a simple structure and is easy to use. The valve is detachable, which effectively extends the service life, and can be regularly inspected and replaced quickly and conveniently.

[0010] However, the above-mentioned check valve has no self-cleaning function, cannot solve the problem of difficult maintenance, and requires irregular manual maintenance.

[0011] Patent application number CN201711391935.7 discloses a one-way throttle valve, including a valve body, a first through-flow groove and a second through-flow groove are arranged in the valve body, a partition is arranged between the first through-flow groove and the second through-flow groove, a first through-flow hole connected to the first through-flow groove is opened on the outer wall of the valve body, and a second through-flow hole connected to the second through-flow groove is also opened on the outer wall of the valve body; a valve core capable of axial movement is arranged in the valve body, a spring is arranged inside the valve core, and a throttling hole is opened in the valve core; when the valve core moves to the left, the spring is compressed, the valve core cuts off the second through-flow groove and can control the opening size of the first through-flow groove, and when the valve core moves to the right, the first through-flow groove and the second through-flow groove are connected. The advantages of the above device are: it integrates a one-way valve and a throttle valve in one, has a reasonable and compact structure, and has a small flow resistance.

[0012] However, the one-way throttle valve is installed inside the pipeline and process, cannot be disassembled for maintenance, and is only suitable for use in conveying media with relatively good components. When used to convey media with complex components, it is easy to fail and cannot be maintained.

[0013] Patent application number CN201721776506.7 discloses a valve for oil and gas transportation capable of controlling the direction of unidirectional flow, comprising a valve body, a plunger in the valve body, and a flow channel arranged on the plunger, wherein the valve body protrudes toward the two ends of the plunger, a connecting cavity and a check cavity are arranged in the valve body, and the two ends of the plunger are respectively arranged in the connecting cavity and the check cavity; one end of the plunger in the connecting cavity is fixedly connected to the valve stem, and a sealing gasket is sleeved on the valve stem; an elastic member is also arranged in the connecting cavity, one end of the elastic member is fixed on the valve stem, and the other end is fixed on the inner wall of the connecting cavity; there is a gap between one end of the plunger in the check cavity and the side wall of the check cavity; it also comprises two feedback pipelines, one end of the two feedback pipelines are respectively connected to the valve body on both sides of the plunger, and the other end is connected to the check cavity; and a stop valve is arranged on both feedback pipelines. The above utility model solves the problem that the plunger valve in the prior art is inconvenient to control unidirectional flow, and realizes the purpose that the plunger valve can flexibly check from two flow directions.

[0014] However, the above-mentioned oil and gas transmission valve capable of controlling the unidirectional flow direction still has no self-cleaning function and still requires manual irregular maintenance and servicing, which cannot solve the problem of difficult maintenance.

[0015] In summary, the above maintenance status of the check valve currently working under harsh working environment conditions needs to be changed. Summary of the invention

[0016] The purpose of the utility model is to provide a fully automatic maintenance-free check valve, which can solve the problems of low labor efficiency, environmental pollution caused by leakage of conveying medium and harm to employees' health during the current maintenance of the check valve, and realize automatic maintenance-free operation of the check valve, avoid environmental pollution caused by venting the conveying medium, protect workers from harm, and improve work efficiency.

[0017] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a fully automatic maintenance-free single-flow valve, provided with a valve ball, a valve body and a valve seat, the valve body is provided with a liquid inlet and a liquid outlet, wherein: the valve ball, the valve seat and the pressure sensor are all installed in a ball cage provided with a guide groove, the ball cage is installed in the valve body and the guide groove is connected to the valve body; the sealing box, the pressure cover, the ball cage seat and the valve body are connected in sequence; the servo motor is fixed on the sealing box with a seal, and the cleaning and dredging shaft with a paddle at the lower end passes through the ball cage seat, the pressure cover and the sealing box to be connected to the servo motor; the servo motor is connected to the PLC in the electrical control cabinet through a cable, and the pressure sensor is wirelessly connected to the PLC.

[0018] Preferably, the servo motor is a linear telescopic stepper motor, the cleaning and dredging shaft is a spline shaft, and the paddles connected below the cleaning and dredging shaft are arranged in more than two pieces.

[0019] Preferably, the servo motor is an asynchronous rotary motor, and the number of the paddles connected below the cleaning and dredging shaft is more than two.

[0020] Preferably, the upper outer circle of the ball cage seat is threadedly connected to the pressure cover, and the lower outer circle is threadedly connected to the inner circle of the ball cage; the pressure cover and the ball cage seat are both provided with a motor shaft through hole larger than the outer diameter of the cleaning and dredging shaft.

[0021] Preferably, the ball cage is a cylindrical body and the inner cavity is a non-uniform diameter inner cavity, and the lower inner cavity of the ball cage is provided with a valve seat retaining step and a limit ring assembly connection step.

[0022] Preferably, the internal thread at the upper end of the ball cage inner cavity is threadedly connected to the ball cage seat and the internal thread in the limit ring assembly connection step at the lower end of the inner cavity is threadedly connected to the limit ring; a sealing ring is installed between the outer wall of the ball cage seat and the outer wall of the ball cage and the inner cavity of the valve body.

[0023] Preferably, the valve seat is installed between the valve seat holding step and the limiting ring in the ball cage; the sealing box, the pressure cover, the ball cage seat and the valve body are threadedly connected in sequence.

[0024] Preferably, the guide grooves in the ball cage are axial vertical grooves, and are provided in two or more grooves; the width of the guide grooves is smaller than the outer diameter of the valve ball and the axial height is three times that of the valve ball.

[0025] Preferably, the upper inner diameter of the valve body is larger than the outer diameter of the ball cage; a gap of 0.5cm-2cm is set between the inner diameter of the valve body and the outer diameter of the ball cage; the inner cavity surface of the valve body, the inner cavity and outer wall surface of the ball cage, and the outer surfaces of the paddles and the cleaning and dredging shaft are all provided with a nano nickel-phosphorus plated anti-corrosion and wear-resistant layer.

[0026] Preferably, the pressure sensor is fixed at the lower end of the ball cage seat and is located inside the ball cage, and the liquid outlet is threadedly connected to the quick connector and is connected to the pipeline or process pipeline through the quick connector through a self-locking clamp.

[0027] Compared with the existing technology, the utility model has the advantages that: the utility model can limit the reverse flow of liquid and ensure the normal use of the check valve without cleaning and maintenance, which is specifically manifested in:

[0028] 1. The utility model can ensure the one-way flow of fluid and prevent the loss of oil well production fluid reinjection in time. The utility model uses a pressure sensor so that the blockage of the valve body can be quantitatively measured, which effectively solves the shortcomings of the currently commonly used one-flow valve that must be regularly inspected and cleaned, and the cleaning is not timely and effective.

[0029] 2. The servo motor in the utility model is connected to a cleaning and unblocking shaft which is provided with a paddle at the lower end and passes through the sealing box, the pressure cover and the ball cage seat. The cleaning and unblocking shaft and the paddle driven by the servo motor clean the ball cage and the inner cavity of the valve body, so that the cleaning and maintenance of the check valve no longer needs to be achieved through manual disassembly, thereby reducing the risk of environmental pollution and protecting the health of employees.

[0030] 3. The overall structural design of the device is reasonable, the working cycle of its cleaning operation is more reasonable, and the wearing parts are easy to disassemble and replace, which improves the conveying efficiency of the conveying pipeline and conveying process.

[0031] 4. The utility model can clean the valve body and the ball cage quickly and effectively, and it only takes one to three minutes to complete the unblocking. There is no need to stop the well or the pump during the cleaning operation, which reduces the production loss caused by the cleaning operation and reduces the damage to the underground pipe and rod and the tripping accident caused by restarting the well after stopping the well.

[0032] In summary, the utility model eliminates or reduces the occurrence of check valve blockage by adding pressure sensors and servo motors, monitors real-time operation, ensures efficient transmission of the conveying medium, and has the function and effect of improving work efficiency and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 It is a structural schematic diagram of the utility model.

[0035] In the figure:

[0036] Sealing box 1, pressure cover 2, cleaning and dredging shaft 3, paddle 4, ball cage 5, valve ball 6, valve body 7, valve seat 8, limit ring 9, pressure sensor 10, servo motor 11, liquid outlet 12, quick connector 13, ball cage seat 14, guide groove 15, liquid inlet 16, sealing element 17. DETAILED DESCRIPTION

[0037] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of the present utility model. The technical solutions in the embodiments of the present utility model will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only part of the embodiments of the present utility model, not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present utility model.

[0038] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0039] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0040] See also Figure 1 A fully automatic maintenance-free check valve is provided with a valve ball 6, a valve body 7 and a valve seat 8, wherein the valve body 7 is provided with a liquid inlet 16 and a liquid outlet 12, wherein: the valve ball 6, the valve seat 8 and the pressure sensor 10 are all installed in a ball cage 5 provided with a guide groove 15, the ball cage 5 is installed in the valve body 7 and the guide groove 15 is connected with the valve body 7; the sealing box 1, the pressure cover 2, the ball cage seat 14 and the valve body 7 are connected in sequence; the servo motor 11 is fixed on the sealing box 1 equipped with a seal 17, and the cleaning and dredging shaft 3 with a paddle 4 at the lower end passes through the ball cage seat 14, the pressure cover 2 and the sealing box 1 to be connected with the servo motor 11; the servo motor 11 is connected to the PLC in the electrical control cabinet through a cable, and the pressure sensor 10 is wirelessly connected to the PLC.

[0041] The utility model uses a servo motor 11 and a pressure sensor 10, and a cleaning program of the check valve is set in the PLC of the electrical control cabinet. Since the ball cage 5 and the valve body 7 in the check valve are blocked by dirt, the fluid flowing therethrough will have a phenomenon of increased pressure. The utility model utilizes this phenomenon, and transmits the change of the fluid pressure therein to the PLC in real time through the pressure sensor 10 installed in the ball cage 5, and the PLC is a programmable logic controller.

[0042] The pressure sensor 10 transmits the received pressure information in the ball cage 5 and the valve body 7 to the PLC. The PLC issues a cleaning instruction to the servo motor 11 according to the cleaning pressure set for the ball cage 5 and the valve body 7 in the one-flow valve cleaning program, and cleans the inside of the ball cage 5 and the valve body 7 through the paddle 4 driven by the cleaning shaft 3.

[0043] After using the utility model, there is no need to stop the medium delivery and the medium in the check valve is emptied, and there is no need to disassemble the check valve. The cleaning work inside the check valve is automatically performed according to the pressure in the ball cage 5 and the valve body 7 and the instruction of the PLC.

[0044] The utility model solves the problems of low labor efficiency, environmental pollution caused by leakage of conveying medium and harm to employees' health caused by the need for irregular manual operation during the current maintenance of the check valve, and realizes automatic manual maintenance of the check valve. It avoids environmental pollution and energy waste caused by venting the conveying medium, ensures that the workers are not harmed, and significantly improves the cleaning efficiency of the check valve.

[0045] On the basis of the above-mentioned embodiment 1, the utility model also has the following embodiments: A preferred embodiment: the servo motor 11 is a linear retractable stepping motor, the cleaning and dredging shaft 3 is a spline shaft, and the paddles 4 connected to the bottom of the cleaning and dredging shaft 3 are provided with more than two pieces. In this way, the cleaning and dredging shaft 3 can drive the paddles 4 to move up and down in the ball cage 5, and can clean the inner wall of the ball cage 5 more comprehensively, so that dirt and dead oil are not adhered to the guide groove 15, and the fluid can pass smoothly from the guide groove 15 and flow out from the liquid outlet 12, and blockage is prevented without disassembling the check valve.

[0046] A preferred embodiment: the servo motor 11 is an asynchronous rotary motor, and the paddles 4 connected to the bottom of the cleaning and dredging shaft 3 are arranged in two or more pieces. The servo motor 11 can drive the cleaning and dredging shaft 3 and the paddles 4 to rotate at a high speed in the ball cage 5 to clean the dirt and dead oil in the ball cage 5 and the valve body 7.

[0047] A preferred embodiment: the upper outer circle of the ball cage seat 14 is threadedly connected to the pressure cover 2, and the lower outer circle is threadedly connected to the inner circle of the ball cage 5; the pressure cover 2 and the ball cage seat 14 are both provided with a motor shaft through hole larger than the outer diameter of the cleaning and dredging shaft 3.

[0048] A preferred embodiment: the ball cage 5 is a cylindrical body and the inner cavity is a non-uniform diameter inner cavity, and the lower inner cavity of the ball cage 5 is provided with a valve seat holding step and a limit ring assembly connection step.

[0049] A preferred embodiment: the internal thread at the upper end of the inner cavity of the ball cage 5 is threadedly connected to the ball cage seat 14 and the internal thread in the limit ring assembly connection step at the lower end of the inner cavity is threadedly connected to the limit ring 9; a sealing ring is installed between the outer wall of the ball cage seat 14 and the outer wall of the ball cage 5 and the inner cavity of the valve body 7.

[0050] A preferred embodiment: the valve seat 8 is installed between the valve seat holding step and the limit ring 9 in the ball cage 5, and the valve seat 8 is pressed tightly under the valve seat holding step in the ball cage 5 by the limit ring 9; the sealing box 1, the gland 2, the ball cage seat 14 and the valve body 7 are threadedly connected in sequence. The cleaning and dredging shaft 3 is sealed with the sealing box 1 by the sealing member 17, and the sealing member 17 is squeezed by the threaded connection between the sealing box 1 and the gland 2 to achieve sealing with the cleaning and dredging shaft 3.

[0051] A preferred embodiment: the guide groove 15 in the ball cage 5 is an axial vertical groove, which is arranged in two or more grooves; the width of the guide groove 15 is smaller than the outer diameter of the valve ball 6 and the axial height is three times that of the valve ball 6. The valve ball 6 completes the opening and closing of the check valve through the pressure difference between the liquid inlet 16 and the liquid outlet 12. The width of the guide groove 15 is smaller than that of the valve ball 6 and the axial height or length is three times that of the valve ball 6, which can effectively increase the transmission area of ​​the fluid in the ball cage 5 and control the moving direction of the valve ball 6.

[0052] A preferred embodiment: the upper inner diameter of the valve body 7 is larger than the outer diameter of the ball cage 5; a gap of 0.5cm-2cm is set between the inner diameter of the valve body 7 and the outer diameter of the ball cage 5, and an annular space is formed between the valve body 7 and the ball cage 5, so that the fluid passing therethrough forms a flushing effect on the inner wall of the valve body 7 and the outer wall of the ball cage 5, delaying scaling and extending the operation cycle; the inner cavity surface of the valve body 7, the inner cavity and outer wall surface of the ball cage 5, and the outer surface of the paddle 4 and the cleaning and dredging shaft 3 are all provided with a nano nickel-phosphorus-plated anti-corrosion and wear-resistant layer. In order to prevent corrosion and wear, a nano nickel-phosphorus-plated anti-corrosion and wear-resistant layer is set on the inner cavity of the valve body 7, the inner cavity and outer wall of the ball cage 5, and the outer surface of the paddle 4 and the cleaning and dredging shaft 3.

[0053] A preferred embodiment: the pressure sensor 10 is fixed to the lower end of the ball cage seat 14 and is located in the ball cage 5, which constantly transmits the pressure changes of the fluid in the valve body 7 and the ball cage 5; the liquid outlet 12 is threadedly connected to the quick connector 13 and connected to the pipeline or process pipeline through the quick connector 13 through a self-locking clamp ring. The quick connector 13 is connected to the process pipeline through a self-locking clamp ring, which avoids the operation risks brought by the welding method and effectively solves the problem that the threads in the process pipeline and the valve body 7 cannot be assembled in both directions and must be connected through a coupling.

[0054] The pressure sensor 10 in the utility model is responsible for transmitting pressure information to the servo motor 11. Through the critical value of the cleaning pressure preset in the PLC, the servo motor 11 is instructed to drive the blade 4 to perform cleaning work, and no manual maintenance and servicing are required, which has a good use effect.

[0055] The embodiments described above are only typical embodiments, but the utility model is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and enlightenment of the utility model. Although the utility model is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the utility model should be included in the protection scope of the utility model. Therefore, the protection scope is not limited to the above description.

Claims

1. A fully automatic maintenance-free check valve, comprising a valve ball, a valve body and a valve seat, wherein the valve body is provided with a liquid inlet and a liquid outlet, wherein: The valve ball, valve seat and pressure sensor are all installed in a ball cage with a guide groove, and the ball cage is installed in the valve body and the guide groove is connected to the valve body; the sealing box, pressure cover, ball cage seat and valve body are connected in sequence; the servo motor is fixed on the sealing box with a seal, and the cleaning and dredging shaft with a paddle at the lower end passes through the ball cage seat, pressure cover and sealing box to be connected to the servo motor; the servo motor is connected to the PLC in the electrical control cabinet through cables, and the pressure sensor is wirelessly connected to the PLC.

2. A fully automatic maintenance-free check valve as claimed in claim 1, characterized in that: The servo motor is a linear telescopic stepping motor, the cleaning and dredging shaft is a spline shaft, and the paddles connected below the cleaning and dredging shaft are arranged in more than two pieces.

3. A fully automatic maintenance-free check valve as claimed in claim 1, characterized in that: The servo motor is an asynchronous rotary motor, and the paddles connected below the cleaning and dredging shaft are arranged in more than two pieces.

4. A fully automatic maintenance-free check valve as claimed in claim 1 or 2, characterized in that: The upper outer circle of the ball cage seat is threadedly connected to the pressure cover, and the lower outer circle is threadedly connected to the inner circle of the ball cage; the pressure cover and the ball cage seat are both provided with a motor shaft through hole larger than the outer diameter of the cleaning and dredging shaft.

5. A fully automatic maintenance-free check valve as claimed in claim 4, characterized in that: The ball cage is a cylindrical body and its inner cavity is a non-uniform diameter inner cavity. The lower inner cavity of the ball cage is provided with a valve seat holding step and a limit ring assembly connection step.

6. A fully automatic maintenance-free check valve as claimed in claim 5, characterized in that: The internal thread at the upper end of the ball cage inner cavity is threadedly connected to the ball cage seat, and the internal thread in the limit ring assembly connection step at the lower end of the inner cavity is threadedly connected to the limit ring; a sealing ring is installed between the outer wall of the ball cage seat and the outer wall of the ball cage and the inner cavity of the valve body.

7. A fully automatic maintenance-free check valve as claimed in claim 6, characterized in that: The valve seat is installed between the valve seat holding step and the limiting ring in the ball cage; the sealing box, the pressure cover, the ball cage seat and the valve body are threadedly connected in sequence.

8. A fully automatic maintenance-free check valve as claimed in claim 7, characterized in that: The guide grooves in the ball cage are axial vertical grooves, which are arranged in two or more lines; the width of the guide grooves is smaller than the outer diameter of the valve ball and the axial height is three times that of the valve ball.

9. A fully automatic maintenance-free check valve as claimed in claim 8, characterized in that: The upper inner diameter of the valve body is larger than the outer diameter of the ball cage; a gap of 0.5cm-2cm is set between the inner diameter of the valve body and the outer diameter of the ball cage; the inner cavity surface of the valve body, the inner cavity and outer wall surface of the ball cage, and the outer surfaces of the paddles and the cleaning and dredging shaft are all provided with a nano nickel-phosphorus plated anti-corrosion and wear-resistant layer.

10. A fully automatic maintenance-free check valve as claimed in claim 4, characterized in that: The pressure sensor is fixed at the lower end of the ball cage seat and is located in the ball cage. The liquid outlet is threadedly connected to the quick connector and is connected to the pipeline or process pipeline through the quick connector and a self-locking clamp ring.

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