A check valve with built-in secondary damping buffer

Abstract

The present invention discloses a check valve with a built-in two-stage damping buffer, which relates to the technical field of check valves and includes: a valve body; two flange rings, which are respectively installed at both ends of the valve body for docking with pipelines; a switch mechanism installed inside the valve body for controlling the switch of the medium flow channel inside the valve body; a first damping mechanism installed at one end of the top of the valve body for controlling the closing speed of the switch mechanism; during the closing process of the valve plate, the force of the torsion spring causes the valve plate to reset, and the valve plate contacts the push rod and presses the push rod back to its position. When the push rod returns, the regulating valve limits the flow rate of the oil reflux, thereby generating resistance, causing the push rod to return slowly, thereby realizing the fast opening and slow closing characteristics of the valve plate. This design effectively reduces the occurrence of water hammer, ensures that the fluid can pass quickly, avoids pressure accumulation, and avoids sudden changes in the fluid flow rate by slowly closing.

Description

Technical Field

[0001] The present invention relates to the technical field of check valves, in particular to a check valve with a built-in two-stage damping buffer. Background Art

[0002] In fluid delivery systems, check valves are key devices used to prevent fluid backflow and are widely used in various industrial and civil fields.

[0003] After searching, the Chinese patent announcement number CN221278553U discloses a check valve, which sets a sealing plane so that the contact surface between the check valve disc and the valve body assembly is a plane, so that the force of the check valve disc acts directly on the vertical sealing gasket, preventing the sealing gasket from being subjected to oblique effects, thereby increasing the service life of the sealing gasket and thus increasing the service life of the check valve. However, there are some problems with traditional check valves during use, especially when the water flow is quickly closed, it is easy to cause water hammer. Water hammer refers to the phenomenon that when the fluid flows in the pipeline, the rapid closing or opening of the valve causes a sharp change in the fluid flow rate, thereby generating an instantaneous high-pressure shock wave in the pipeline. This high-pressure shock wave will cause serious impact and damage to the pipeline and equipment, shorten the service life of the equipment, and increase maintenance costs;

[0004] Therefore, in view of the shortcomings of existing check valves in preventing water hammer, it is necessary to design a check valve with a built-in two-stage damping buffer, which can reduce the water hammer effect through the cooperation of two-stage damping, while achieving the effect of fast opening and slow closing, and can effectively suppress the swing of the valve plate, so as to improve the safety and reliability of the pipeline system and reduce equipment wear and maintenance costs. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a check valve with a built-in two-stage damping buffer, which solves the problem in the background art that the prior check valve has deficiencies in preventing water hammer.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a check valve with a built-in two-stage damping buffer, comprising:

[0007] Valve body;

[0008] There are two flange rings, which are installed at both ends of the valve body for connecting with the pipeline;

[0009] A switch mechanism is installed inside the valve body and is used to control the opening and closing of the medium flow channel inside the valve body;

[0010] A first damping mechanism is installed at one end of the top of the valve body and is used to control the closing speed of the switch mechanism;

[0011] The second damping mechanism is installed at the bottom of the valve body, and its interior is communicated with the interior of the valve body. The second damping mechanism is used to buffer the water hammer inside the valve body.

[0012] Preferably, the switching mechanism includes a limit block, the outer wall of the limit block is annular in structure, and the limit block is fixedly installed inside the valve body, a semicircular valve plate is provided on one side of the limit block, and two valve plates are provided, and the two valve plates are symmetrically distributed with each other; the switching mechanism can effectively achieve precise control of the fluid channel by providing two symmetrically distributed semicircular valve plates and an annular limit block, thereby ensuring that the valve has good sealing performance and stable fluid flow characteristics during the opening and closing process.

[0013] Preferably, one side surface of the valve plate fits tightly with the surface of the limit block, the contact surface between the limit block and the valve plate is provided with a rubber coating, one end of the valve plate is threadedly connected to the threaded rod, both ends of the threaded rod are connected to the valve body through nuts, and a torsion spring is sheathed on the outside of the threaded rod; this design significantly enhances the sealing performance of the valve through the tight fit between the valve plate and the limit block and the provision of the rubber coating, and effectively prevents fluid leakage; at the same time, the threaded connection between the valve plate and the threaded rod and the assembly of the torsion spring not only ensure that the valve plate can be stably opened under the action of fluid pressure, but also can quickly reset and close when the fluid pressure disappears, further improving the reliability and response speed of the valve.

[0014] Preferably, two pressure chambers are provided inside the limit block, a push rod is provided inside the pressure chamber, the interior of the pressure chamber is a hollow structure, the interior of the pressure chamber is connected with the guide port, the guide port is connected with the guide groove, the guide groove is opened on the outer wall surface of the limit block, the guide groove is an arc-shaped structure, the outer wall surface of the limit block is tightly fitted with the inner wall surface of the valve body; a limiting ring is provided at one end of the push rod, the outer wall of the push rod is tightly fitted with the pressure chamber, and the outer wall of the push rod is slidably connected with the inside of the pressure chamber, by providing two pressure chambers and a push rod matched therewith inside the limit block, and utilizing the oil pressure in the pressure chamber to drive the telescopic action of the push rod, thereby realizing control of the closing speed of the valve plate, and the connecting structure of the guide port and the guide groove ensures the smooth flow of oil, further improving the buffering performance and reliability of the valve.

[0015] Preferably, the other end of the push rod is a hemispherical structure, and one end of the push rod is connected to the magnet through a connecting shaft. The magnet is connected to the valve plate through magnetic attraction, and balls are embedded in the surface of the magnet. The surface of the ball is in sliding contact with the surface of the magnet, and there are multiple balls distributed in a ring shape with equal intervals. Through the hemispherical structure of the end of the push rod and the magnetic connection of the magnet, flexible contact and stable connection between the valve plate and the push rod are achieved. At the same time, the balls embedded on the surface of the magnet can effectively reduce the friction between the valve plate and the magnet, ensuring that the valve plate can move smoothly and smoothly during opening and closing, further improving the operating stability and service life of the valve.

[0016] Preferably, the first damping mechanism includes a connecting pipe, the connecting pipe is connected to the limit block, the surface of the limit block is provided with a hole groove connected to the inside of the connecting pipe, one end of the top of the connecting pipe is connected to the inside of the pressure tank, the inside of the pressure tank is provided with a first piston, one end of the top of the pressure tank is connected to the regulating valve, the top cavity of the pressure tank and the inside of the pressure chamber are both filled with oil, the other end of the regulating valve is connected to one end of the pressure pipe, and the other end of the pressure pipe is connected to the inside of the guide groove; through the synergistic effect of the connecting pipe, pressure tank, first piston, regulating valve and pressure pipe and other components, a complete oil pressure damping system is constructed. Water flows into the connecting pipe through the hole groove on the surface of the limit block, thereby pushing the first piston in the pressure tank to move, squeezing the oil so that it flows into the pressure chamber through the pressure pipe, thereby driving the push rod to move. The regulating valve controls the reflux speed of the oil and accurately adjusts the extension and contraction speed of the push rod, thereby achieving the fast opening and slow closing effect of the valve plate, effectively reducing the occurrence of water hammer, and ensuring that the closing process of the valve is smooth and controllable.

[0017] Preferably, the second damping mechanism includes a buffer groove, which is arranged in an inclined shape. One end of the top of the buffer groove is connected to the interior of the valve body. A second piston is arranged inside the buffer groove. The outer wall of the second piston is tightly fitted with the inner wall surface of the buffer groove. An annular protrusion is provided inside the buffer groove. A second spring is provided inside the buffer groove. One end of the top of the second spring is connected to the second piston. The inclined buffer groove, the tightly fitted second piston, and the connected second spring form a highly efficient mechanical buffer system. When water hammer pressure is generated inside the valve body, the water flow impacts the second piston, causing it to move downward along the buffer groove and compress the second spring, thereby absorbing and buffering the impact energy generated by the water hammer, effectively reducing the impact force of the water hammer on the valve body and the piping system, and protecting the equipment from damage.

[0018] Preferably, an adjustment block is provided at one end of the bottom of the second spring. The adjustment block is rotatably connected to one end of the adjustment rod. The outer wall of the adjustment rod is threadedly connected to the end cap via a thread, and the end cap is connected to the bottom end of the buffer groove. A knob is mounted on the bottom end of the adjustment rod. The combination of the adjustment block, adjustment rod, end cap, and knob enables the adjustability of the preload force of the second spring. By turning the knob, the adjustment rod moves up and down in conjunction with the threads of the end cap, driving the adjustment block to change position, thereby adjusting the compression degree of the second spring and, in turn, changing the damping characteristics of the buffer system. This allows the buffer strength to be flexibly adjusted according to different operating conditions and water hammer pressure, thereby improving the adaptability and reliability of the valve.

[0019] The present invention provides a check valve with a built-in two-stage damping buffer. It has the following beneficial effects:

[0020] In a fluid delivery system, this check valve with a built-in two-stage damping buffer is connected to the pipeline via flange rings at each end of the valve body, ensuring a sealed connection with the pipeline system. When water flows from one end of the valve body to the other, the pressure of the water acts on the valve disc inside the valve body, causing it to open and establish a fluid flow path. Simultaneously, water flows through the holes and grooves on the surface of the stop block into the connecting pipe and further into the pressure tank, pushing the first piston inside the pressure tank upward. The upward movement of the first piston squeezes the oil in the pressure tank, generating oil pressure that in turn pushes the push rod in the pressure chamber to extend. During the closing process of the valve disc, the force of the torsion spring forces the valve disc back into position, contacting the push rod and forcing it back into its original position. As the push rod returns, its action squeezes the oil in the pressure chamber, forcing it back into the pressure tank through the regulating valve. The regulating valve limits the return flow of the oil, creating resistance that slows the return of the push rod, thereby achieving the fast-opening and slow-closing characteristics of the valve disc. This design effectively reduces the occurrence of water hammer, ensuring that fluid can pass quickly and avoiding pressure accumulation. At the same time, by slowly closing, it avoids sudden changes in fluid flow rate, making the closing process smoother. The two-stage damping buffer of this solution consists of a first damping mechanism and a second damping mechanism, which respectively provide dual buffering for the valve closing process and water hammer impact. The first damping mechanism controls the closing speed of the valve plate through the oil pressure system, achieving a fast opening and slow closing characteristic, avoiding sudden changes in fluid flow rate caused by rapid closing, thereby reducing water hammer pressure. The second damping mechanism effectively buffers the water hammer generated inside the valve body through a mechanical buffer system, further releasing the pressure generated by the water hammer and reducing the impact force on the valve plate and other components, thereby significantly reducing water hammer pressure and protecting pipelines and equipment from impact damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the top view of the structure of the present invention;

[0023] Figure 3 It is a schematic diagram of the front view structure of the present invention;

[0024] Figure 4 Schematic diagram of the internal structure of the present invention;

[0025] Figure 5 Schematic diagram of the structure of the first damping mechanism of the present invention;

[0026] Figure 6 This is a schematic diagram of the switch mechanism structure of the present invention;

[0027] Figure 7 This is a schematic diagram of the magnet structure of the present invention;

[0028] Figure 8 It is a schematic diagram of the push rod structure of the present invention.

[0029] In the figure, 1. valve body; 2. flange ring; 3. switch mechanism; 301. limit block; 302. valve plate; 303. threaded rod; 304. torsion spring; 305. pressure chamber; 306. guide port; 307. guide groove; 308. push rod; 309. limit ring; 310. magnet; 311. ball; 312. connecting shaft; 4. first damping mechanism; 401. connecting pipe; 402. first piston; 403. pressure tank; 404. regulating valve; 405. pressure pipe; 5. second damping mechanism; 501. buffer groove; 502. second piston; 503. spring; 504. regulating block; 505. end cover; 506. regulating rod; 507. knob. DETAILED DESCRIPTION

[0030] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention. Example 1

[0031] See also Figure 1-8 The embodiment of the present invention provides a technical solution: a check valve with a built-in two-stage damping buffer, comprising:

[0032] Valve body 1;

[0033] There are two flange rings 2, which are installed at both ends of the valve body 1 for connecting with the pipeline;

[0034] The switch mechanism 3 is installed inside the valve body 1 and is used to control the opening and closing of the medium flow channel inside the valve body 1;

[0035] The first damping mechanism 4 is installed at one end of the top of the valve body 1 and is used to control the closing speed of the switch mechanism 3;

[0036] The second damping mechanism 5 is installed at the bottom of the valve body 1, and its interior is connected to the interior of the valve body 1. The second damping mechanism 5 is used to buffer the water hammer inside the valve body 1;

[0037] This check valve with a built-in two-stage damping buffer can effectively solve the problem of traditional check valves being prone to water hammer when the water flow is quickly closed through the coordinated action of the valve body 1, flange ring 2, switch mechanism 3, first damping mechanism 4, and second damping mechanism 5. Specifically, the first damping mechanism 4 can control the closing speed of the switch mechanism 3, achieving the effect of fast opening and slow closing, avoiding the rapid change in fluid flow rate caused by rapid closing, thereby reducing water hammer pressure and protecting pipelines and equipment from impact damage. At the same time, the second damping mechanism 5 can effectively buffer the water hammer generated inside the valve body 1, further releasing the pressure generated by the water hammer, reducing the impact force on the valve plate 302 and other components, extending the service life of the equipment, and reducing maintenance costs. The two-stage damping buffer composed of the first damping mechanism and the second damping mechanism provides dual buffering for the valve closing process and water hammer impact, thereby significantly reducing water hammer pressure and protecting pipelines and equipment from impact damage. Example 2

[0038] See also Figure 1-8, the embodiment of the present invention provides a technical solution: a check valve with a built-in two-stage damping buffer, the switch mechanism 3 includes a limit block 301, the outer wall of the limit block 301 is a ring-shaped structure, and the limit block 301 is fixedly installed inside the valve body 1, a semicircular valve plate 302 is provided on one side of the limit block 301, and two valve plates 302 are provided, and the two valve plates 302 are symmetrically distributed with each other; one side surface of the valve plate 302 is tightly fitted with the surface of the limit block 301, and the contact surface between the limit block 301 and the valve plate 302 is provided with a rubber coating, and one end of the valve plate 302 is connected to the thread The rod 303 is threadedly connected, and both ends of the threaded rod 303 are connected to the valve body 1 through nuts. A torsion spring 304 is sleeved on the outside of the threaded rod 303; two pressure chambers 305 are provided inside the limit block 301, and a push rod 308 is provided inside the pressure chamber 305. The interior of the pressure chamber 305 is a hollow structure, and the interior of the pressure chamber 305 is connected to the guide port 306, and the guide port 306 is connected to the guide groove 307. The guide groove 307 is opened on the outer wall surface of the limit block 301, and the guide groove 307 is an arc-shaped structure. The outer wall surface of the limit block 301 is connected to the inner wall surface of the valve body 1 The first resistance is 310, and the second resistance is 311. The first resistance is 310, and the second resistance is 311. The first resistance is 310, and the second resistance is 311. The first resistance is 310, and the second resistance is 311. The mechanism 4 includes a connecting pipe 401, which is connected to the limit block 301. The limit block 301 has a surface provided with a hole groove communicating with the interior of the connecting pipe 401. One end of the top of the connecting pipe 401 communicates with the interior of a pressure tank 403. A first piston 402 is provided inside the pressure tank 403. One end of the top of the pressure tank 403 communicates with a regulating valve 404. The top cavity of the pressure tank 403 and the interior of the pressure chamber 305 are both filled with oil. The other end of the regulating valve 404 communicates with one end of the pressure pipe 405, and the other end of the pressure pipe 405 communicates with the interior of the guide groove 307.

[0039] In this embodiment, the valve body 1 is connected to the pipeline through the flange ring 2. When water flows from one end of the valve body 1 to the other end, the valve plate 302 inside the valve body 1 will open under the pressure of the water flow, thereby allowing the water to flow. At the same time, under the action of the water flow pressure, water will enter the connecting pipe 401 through the holes and grooves on the surface of the limit block 301, and then enter the pressure tank 403 through the connecting pipe 401, pushing the first piston 402 inside the pressure tank 403 to move upward. While moving upward, the first piston 402 squeezes the oil inside, and then the push rod 308 inside the pressure chamber 305 can be pushed out under the action of the oil pressure. When the valve plate 302 is closed, the valve plate 302 is reset under the action of the torsion spring 304, and then the valve plate 302 contacts one end of the push rod 308. When the valve plate 302 presses the push rod 308 to return to its original position, the push rod 308 will squeeze the oil inside the pressure chamber 305, causing the oil inside the pressure chamber 305 to flow back into the pressure tank 403. In the process of returning to the pressure chamber 305, the oil will pass through the regulating valve 404. Under the action of the regulating valve 404, the flow of oil inside the pipeline will be restricted, so that the oil inside the pressure chamber 305 can only slowly flow back into the pressure tank 403, thereby causing the push rod 308 to generate resistance, preventing the valve plate 302 from closing quickly, thereby achieving the effect of fast opening and slow closing, which can effectively reduce the occurrence of water hammer. Fast opening ensures that the fluid can pass quickly and reduce pressure accumulation, while slow closing avoids sudden changes in fluid flow rate, making the closing process smoother, thereby reducing water hammer pressure and protecting pipelines and equipment from impact damage. Secondly, fast opening and slow closing can extend the service life of equipment, reduce mechanical stress and vibration caused by water hammer, and reduce equipment wear and maintenance costs;

[0040] When the valve plate 302 opens, the push rod 308 slowly extends under the action of the water pressure, and the magnet 310 at one end of the push rod 308 is attracted to the surface of the valve plate 302, so that the valve plate 302 can be connected to the push rod 308 through magnetic attraction. Under the damping effect of the push rod 308, the valve plate 302 can be suppressed from swinging when opening. During the opening process of the butterfly valve, the valve plate 302 is easily swung due to the action of fluid dynamics, especially when impacted by water flow. This swinging not only causes the valve plate 302 to wear faster at the connection with the threaded rod 303, but also loosens the connection between the valve plate 302 and the valve body 1. Under the damping suppression of the push rod 308, the swing of the valve plate 302 can be effectively reduced. Example 3

[0041] See also Figure 1-8, an embodiment of the present invention provides a technical solution: a check valve with a built-in two-stage damping buffer, the second damping mechanism 5 includes a buffer groove 501, the buffer groove 501 is arranged in an inclined shape, and the top end of the buffer groove 501 is connected to the interior of the valve body 1, a second piston 502 is arranged inside the buffer groove 501, the outer wall of the second piston 502 is tightly fitted with the inner wall surface of the buffer groove 501, an annular protrusion structure is provided inside the buffer groove 501, and a second spring 503 is provided inside the buffer groove 501, and the top end of the second spring 503 is connected to the second piston 502; an adjusting block 504 is provided at the bottom end of the second spring 503, and the adjusting block 504 is rotatably connected to one end of the adjusting rod 506, the outer wall of the adjusting rod 506 is threadedly connected to the end cover 505 through a thread, the end cover 505 is connected to the bottom end of the buffer groove 501, and the bottom end of the adjusting rod 506 is covered with a knob 507;

[0042] In this embodiment, when a water hammer effect occurs at one end of the valve body 1, the pressure of the water flow will compress the second piston 502 inside the buffer groove 501, so that the second piston 502 can squeeze the spring 503 inside the buffer groove 501, thereby releasing the pressure generated by the water hammer, thereby reducing the impact force of the water hammer on the valve plate 302. When the water hammer disappears, the second piston 502 can be reset under the action of the second spring 503. By rotating the knob 507, the knob 507 can drive the adjusting rod 506 to rotate, and the adjusting rod 506 can drive the adjusting block 504 to move while rotating, so that the adjusting block 504 can adjust the pressure of the spring 503, thereby improving the adjustability of the second damping mechanism 5.

[0043] Working Principle: When fluid enters the check valve from a pipeline, it first passes through the flange rings 2 at each end of the valve body 1, connecting to the pipeline and allowing the fluid to enter the valve body 1. Under the pressure of the fluid, the valve plate 302 in the switch mechanism 3 opens, allowing the fluid to flow smoothly through the medium flow channel of the valve body 1. At this point, the fluid pressure enters the connecting pipe 401 through the holes in the surface of the stop block 301 and further into the pressure tank 403, pushing the first piston 402 in the pressure tank 403 upward. The movement of the first piston 402 displaces the oil in the pressure tank 403, forcing the oil to flow through the pressure pipe 405 into the pressure chamber 305 of the stop block 301, thereby pushing the push rod 308 to extend. When the valve plate 302 closes under the action of the torsion spring 304, it contacts the push rod 308 and forces it back into place. During this process, the push rod 308 displaces the oil in the pressure chamber 305, causing the oil to slowly flow back into the pressure tank 403 through the regulating valve 404. The regulating valve 404 plays a role in limiting the oil flow in this process, thereby ensuring that the valve plate 302 can achieve the effect of fast opening and slow closing when closing, effectively reducing the occurrence of water hammer.

[0044] At the same time, the excess water pressure will be quickly transmitted to the buffer groove 501 of the second damping mechanism 5, pushing the second piston 502 to move downward, thereby compressing the second spring 503 in the buffer groove 501. During the compression process, the second spring 503 absorbs and buffers the instantaneous high-pressure shock wave generated by the water hammer, thereby effectively protecting the components inside the valve body 1 and the entire pipeline system from damage caused by the water hammer impact. When the water hammer pressure disappears, the second spring 503 pushes the second piston 502 to reset and return to its initial state under the action of its own elastic force. By turning the knob 507, the position of the adjusting rod 506 can be adjusted, thereby changing the pressure of the adjusting block 504 on the second spring 503, thereby adjusting the buffering capacity of the second damping mechanism 5 to meet different working conditions.

[0045] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0046] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A check valve with a built-in two-stage damping buffer, characterized in that: include: Valve body (1); Flange rings (2), two of which are provided and respectively mounted on both ends of the valve body (1) for docking with the pipeline; A switch mechanism (3) is installed inside the valve body (1) and is used to control the opening and closing of the medium flow channel inside the valve body (1); A first damping mechanism (4) is mounted on one end of the top of the valve body (1) and is used to control the closing speed of the switch mechanism (3); a second damping mechanism (5) mounted on the bottom of the valve body (1), the interior of which is in communication with the interior of the valve body (1), and the second damping mechanism (5) is used to buffer water hammer inside the valve body (1); The first damping mechanism (4) comprises a connecting pipe (401), the connecting pipe (401) is connected to the limit block (301), a hole groove is provided on the surface of the limit block (301) and is communicated with the interior of the connecting pipe (401), one end of the top of the connecting pipe (401) is communicated with the interior of the pressure tank (403), a first piston (402) is provided inside the pressure tank (403), one end of the top of the pressure tank (403) is communicated with the regulating valve (404), the top cavity of the pressure tank (403) and the interior of the pressure chamber (305) are both filled with oil, the other end of the regulating valve (404) is communicated with one end of the pressure pipe (405), and the other end of the pressure pipe (405) is communicated with the interior of the guide groove (307); The second damping mechanism (5) comprises a buffer groove (501), the buffer groove (501) is arranged in an inclined shape, one end of the top of the buffer groove (501) is connected to the interior of the valve body (1), a second piston (502) is arranged inside the buffer groove (501), the outer wall of the second piston (502) is tightly fitted with the inner wall surface of the buffer groove (501), an annular protruding structure is arranged inside the buffer groove (501), and a second spring (503) is arranged inside the buffer groove (501), and one end of the top of the second spring (503) is connected to the second piston (502).

2. A check valve with a built-in two-stage damping buffer according to claim 1, characterized in that: The switch mechanism (3) comprises a limit block (301), the outer wall of the limit block (301) is annular in structure, and the limit block (301) is fixedly installed inside the valve body (1), and a semicircular valve plate (302) is provided on one side of the limit block (301), and two valve plates (302) are provided, and the two valve plates (302) are symmetrically distributed with respect to each other.

3. A check valve with a built-in two-stage damping buffer according to claim 2, characterized in that: One side surface of the valve plate (302) is tightly fitted with the surface of the limit block (301); the contact surface between the limit block (301) and the valve plate (302) is provided with a rubber coating; one end of the valve plate (302) is threadedly connected to the threaded rod (303); both ends of the threaded rod (303) are connected to the valve body (1) via nuts; and a torsion spring (304) is sleeved on the outside of the threaded rod (303).

4. A check valve with a built-in two-stage damping buffer according to claim 3, characterized in that: Two pressure chambers (305) are provided inside the limit block (301), and a push rod (308) is provided inside the pressure chamber (305). The interior of the pressure chamber (305) is a hollow structure. The interior of the pressure chamber (305) is communicated with the guide port (306), and the guide port (306) is communicated with the guide groove (307). The guide groove (307) is opened on the outer wall surface of the limit block (301), and the guide groove (307) is an arc-shaped structure. The outer wall surface of the limit block (301) is closely fitted with the inner wall surface of the valve body (1); a limiting ring (309) is provided at one end of the push rod (308), and the outer wall of the push rod (308) is closely fitted with the pressure chamber (305), and the outer wall of the push rod (308) is slidably connected to the interior of the pressure chamber (305).

5. A check valve with a built-in two-stage damping buffer according to claim 4, characterized in that: The other end of the push rod (308) is in a hemispherical structure, and one end of the push rod (308) is connected to the magnet (310) via a connecting shaft (312). The magnet (310) is connected to the valve plate (302) via magnetic attraction, and a ball (311) is embedded on the surface of the magnet (310). The surface of the ball (311) is in sliding contact with the surface of the magnet (310), and a plurality of the balls (311) are distributed in a ring-shaped manner with equal spacing.

6. A check valve with a built-in two-stage damping buffer according to claim 5, characterized in that: An adjusting block (504) is provided at one end of the bottom of the second spring (503), and the adjusting block (504) is rotatably connected to one end of the adjusting rod (506). The outer wall of the adjusting rod (506) is threadedly connected to the end cover (505) through a thread, and the end cover (505) is connected to one end of the bottom of the buffer groove (501). A knob (507) is mounted on one end of the bottom of the adjusting rod (506).

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