Check valve with isolation function and ventilation system

Abstract

The embodiment of the utility model provides a check valve and a ventilation system with an isolation function, the check valve comprises a valve body, a valve blade, a connecting rod assembly and a heavy hammer assembly, the valve body is provided with a channel, the valve blade is arranged in the channel, and the connecting rod assembly is arranged in the channel. The connecting rod assembly is arranged on the side wall of the valve body, the two ends of the connecting rod assembly are connected with the valve blade and the heavy hammer assembly respectively, and when airflow flows, the valve blade rotates under the action of the airflow and drives the heavy hammer assembly to swing through the connecting rod assembly so that a channel can be opened or closed. The check valve further comprises a locking assembly arranged on the heavy hammer assembly, and the locking assembly is used for locking the heavy hammer assembly when the channel is closed. According to the embodiment, the heavy hammer assembly is locked through the locking assembly, so that the heavy hammer assembly cannot move, the ventilation system is stopped, at the moment, the fan can be isolated without additionally arranging an isolating valve, the number of valves needing to be installed is reduced, and the arrangement of the ventilation system becomes simple.

Description

TECHNICAL FIELD

[0001] The utility model relates to a ventilation system field especially a check valve and ventilation system with isolation function. BACKGROUND

[0002] Isolation valve and check valve are commonly used valve devices in ventilation system, wherein, isolation valve is used to close or open air duct to block or allow airflow, check valve is used to prevent airflow backflow. Figure 1 In some application scenarios, such as ventilation system with multiple parallel fans 20, check valve 30 and isolation valve 10 are often cooperatively arranged, generally isolation valve 10 and check valve 30 are arranged at the inlet and outlet of each fan 20 respectively, and static pressure tank 40 is arranged at the outlet of multiple fans 20, check valve 30 is used to prevent airflow backflow of one or more fans 20 in parallel operation during start / stop process, and isolation valve 10 is used to realize fan 20 shutdown or maintenance isolation function.

[0003] But the pipeline of such ventilation system is often large in size, resulting in large size of required valve, and valve arrangement and maintenance space need to be specially considered during design, especially during design of ventilation system in control area of nuclear power plant, due to limited space in nuclear island, if check valve and isolation valve are arranged at the same time, due to space limitation, the arrangement of ventilation system is difficult. SUMMARY

[0004] The utility model provides a check valve and ventilation system with isolation function, aims at solving the problem of difficult arrangement of existing ventilation system due to limited space when installing check valve and isolation valve at the same time.

[0005] The utility model embodiment provides a check valve, include: valve body, valve leaf, connecting rod assembly and weight assembly, the valve body has passageway, the valve leaf sets up in the passageway, the connecting rod assembly sets up in the valve body lateral wall and the both ends of connecting rod assembly are connected valve leaf and weight assembly respectively, when airflow flows, the valve leaf rotates under the action of airflow and drives weight assembly swing through connecting rod assembly to make passageway open or close;

[0006] The check valve further includes a locking assembly provided on the weight assembly, and the locking assembly is used to lock the weight assembly when the passageway is closed.

[0007] Specifically, the weight assembly includes a weight, a cantilever, and a weight seat, the weight seat is installed outside the valve body, one end of the cantilever is rotatably connected to the weight seat, the other end of the cantilever is connected to the weight, and the weight seat and / or the cantilever is provided with a locking hole, and the locking assembly is connected in the locking hole.

[0008] Specifically, the locking assembly is a bolt or a positioning pin.

[0009] Specifically, the check valve further comprises a transmission plate, the valve leaf is provided in plurality, and the connecting rod assembly is provided in plurality of groups, one end of one group of connecting rod assemblies is connected to the weight assembly, and one end of the remaining connecting rod assemblies is connected to the transmission plate.

[0010] Specifically, each group of connecting rod assemblies comprises a connecting rod and a connecting rod seat, the connecting rod seat is arranged outside the valve body, one end of the connecting rod is connected to the connecting rod seat by penetrating the inner wall of the valve body, the other end of the connecting rod is connected to the valve body by penetrating the other inner wall of the valve body, and the connecting rod seats are connected by the transmission plate.

[0011] Specifically, one end of the connecting rod is further connected to the cantilever by penetrating the weight seat.

[0012] Specifically, the valve leaf is provided with a sealing element at the end.

[0013] Specifically, when the airflow disappears, the valve leaf rotates under the gravity of the weight assembly to close the passage.

[0014] The utility model embodiment further provides a ventilation system comprising the check valve.

[0015] Specifically, the ventilation system further comprises a plurality of parallelly arranged fans and static pressure boxes, the static pressure boxes are connected to the air outlets of the plurality of fans, the check valve is provided in plurality, and each check valve is arranged between each fan and static pressure box.

[0016] The utility model embodiment provides a check valve and ventilation system with isolation function, the check valve comprises a valve body, a valve leaf, a connecting rod assembly and a weight assembly, the valve body has a passage, the valve leaf is arranged in the passage, the connecting rod assembly is arranged on the side wall of the valve body, and both ends of the connecting rod assembly are connected to the valve leaf and the weight assembly respectively, when the airflow flows, the valve leaf rotates under the action of the airflow and drives the weight assembly to swing through the connecting rod assembly to open or close the passage, the check valve further comprises a locking assembly arranged on the weight assembly, and the locking assembly is used for locking the weight assembly when the passage is closed. In the embodiment, the locking assembly is used for locking the weight assembly, so that the weight assembly cannot move, thereby realizing the shutdown of the ventilation system, the fan can be isolated without additionally arranging an isolation valve, the number of valves to be installed is reduced, and the arrangement of the ventilation system is simple. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical scheme of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings described in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 The valve design schematic diagram of the fan inlet and outlet in the ventilation system with multiple fans in parallel is provided for the embodiment of the present application.

[0019] Figure 2 The front view diagram of the check valve with the isolation function is provided for the embodiment of the present application.

[0020] Figure 3 The side view diagram of the check valve with the isolation function is provided for the embodiment of the present application.

[0021] Figure 4 The side view diagram of the check valve without the installed weight assembly is provided for the embodiment of the present application.

[0022] Figure 5 The valve design schematic diagram of the fan inlet and outlet in the ventilation system with multiple fans in parallel is provided for the embodiment of the present application.

[0023] The identification in the figure is as follows:

[0024] In the prior art, 10, isolation valve; 20, fan; 30, check valve; 40, static pressure tank;

[0025] In the embodiments of the present application, 1, check valve; 11, valve body; 111, passage; 12, valve leaf; 13, connecting rod assembly; 131, connecting rod; 132, connecting rod seat; 14, weight assembly; 141, weight; 142, cantilever; 143, weight seat; 15, locking assembly; 151, locking hole; 16, transmission plate; 17, sealing element;

[0026] 2, ventilation system; 21, fan; 22, static pressure tank. DETAILED DESCRIPTION

[0027] The technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0028] It should be understood that the terms "comprises" and "comprising," when used in this specification and the following claims, indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0029] It should also be understood that the terms used in the specification and the appended claims are intended to describe certain embodiments and do not intentionally limit the scope of the application. As used in the specification and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0030] It should further be understood that the term "and / or" as used in the specification and the appended claims is intended to mean an addition of one or more of the conjuncted items to the list of items, and is intended to cover all possible combinations of the items.

[0031] Referring to Figures 2-4 The embodiment of the present application provides a check valve 1, which comprises a valve body 11, a valve leaf 12, a connecting rod assembly 13 and a weight assembly 14. The valve body 11 has a passage 111, the valve leaf 12 is arranged in the passage 111, the connecting rod assembly 13 is arranged on the side wall of the valve body 11, and two ends of the connecting rod assembly 13 are connected with the valve leaf 12 and the weight assembly 14 respectively. When the airflow flows, the valve leaf 12 rotates under the action of the airflow and drives the weight assembly 14 to swing through the connecting rod assembly 13 to open or close the passage 111.

[0032] The check valve 1 further comprises a locking assembly 15 arranged on the weight assembly 14, and the locking assembly 15 is used for locking the weight assembly 14 when the passage 111 is closed.

[0033] In the embodiment, the check valve 1 comprises the valve body 11, the valve leaf 12, the connecting rod assembly 13, the weight assembly 14 and the locking assembly 15. The valve body 11 is a main support structure of the whole check valve 1 and can be cast or welded by using a metal material (such as carbon steel, stainless steel, etc.) to ensure that it has sufficient strength and sealing performance. The valve body 11 is arranged as a frame structure with a hollow middle part and a surrounding connection in sequence around the periphery. The hollow area is the passage 111 for airflow circulation. An installation hole is arranged on the side wall of the valve body 11 and used for installing the connecting rod assembly 13. One end of the connecting rod assembly 13 extends out of the outside of the valve body 11 and is connected with the weight assembly 14. The other end of the connecting rod assembly 13 extends from one side wall of the valve body 11 to the other side wall, so as to fix the valve leaf 12 in the passage 111. The valve leaf 12 can be made of a light and high-strength material, such as aluminum alloy or engineering plastic, to reduce the airflow driving force required when the valve leaf 12 rotates.

[0034] The working principle of the check valve 1 is that the airflow pushes the valve leaf 12 to rotate, and drives the heavy hammer assembly 14 to swing through the connecting rod assembly 13, so as to realize the opening or closing of the passage 111. Specifically, the airflow flows in the positive direction (the arrow direction of the airflow is positive) Figure 3 When the airflow flows in the reverse direction of the airflow, the valve leaf 12 is flipped to the closed state under the torque generated by the gravity of the heavy hammer assembly 14. When isolation is needed, the heavy hammer assembly 14 can be locked by the locking assembly 15, so as to limit the swing of the heavy hammer assembly 14, and lock the passage 111 in the closed state. At this time, the check valve 1 has the isolation function, which is convenient for professionals to isolate and maintain the fan 21 of the ventilation system 2.

[0035] Specifically, as shown in Figures 2-3 The heavy hammer assembly 14 includes a heavy hammer 141, a cantilever 142, and a heavy hammer seat 143. The heavy hammer seat 143 is installed on the outer side of the valve body 11. One end of the cantilever 142 is rotatably connected to the heavy hammer seat 143, and the other end of the cantilever 142 is connected to the heavy hammer 141. The heavy hammer seat 143 and / or the cantilever 142 is provided with a locking hole 151, and the locking assembly 15 is connected in the locking hole 151.

[0036] In this embodiment, the heavy hammer seat 143 is preferably designed as a plate structure, which is firmly installed on the outer side wall of the valve body 11 by welding or bolt connection. A first shaft hole is arranged on the heavy hammer seat 143 for cooperation with the cantilever 142. The cantilever 142 is made of high-strength aluminum alloy and has an elongated rod shape. The cantilever 142 is provided with a second shaft hole at a position corresponding to the first shaft hole. One end of the connecting rod assembly 13 passes through the first shaft hole and the second shaft hole in sequence to be connected with the heavy hammer seat 143 and the cantilever 142. The heavy hammer 141 is composed of a plurality of metal blocks. In specific implementation, the number of metal blocks is set according to actual working requirements.

[0037] When the locking hole 151 is arranged on the heavy hammer seat 143, it can be arranged on both sides of the first shaft hole. After the passage 111 is closed, the locking assembly 15 is screwed into the locking holes 151 on both sides, and the locking assembly 15 protrudes out of the locking holes 151 and the protruding end is higher than the thickness of the cantilever 142, so as to limit the left and right rotation of the cantilever 142 and the swing of the heavy hammer assembly 14. When the locking hole 151 is arranged on the cantilever 142, it can be directly arranged on the overlapping area of the cantilever 142 and the heavy hammer seat 143. After the passage 111 is closed, the locking assembly 15 is screwed into the locking hole 151 and abuts against the heavy hammer seat 143, so as to limit the rotation of the cantilever 142. When the locking hole 151 is arranged on both the cantilever 142 and the heavy hammer seat 143 (as shown in Figure 3When the locking assembly 15 is used, the locking assembly 15 is directly rotated out of the locking hole 151.

[0038] Specifically, the locking assembly 15 is a bolt or a positioning pin.

[0039] In the embodiment, both the bolt and the positioning pin can provide reliable locking force for the weight assembly 14. When the isolation function needs to be performed, the bolt or the positioning pin is matched with the locking hole 151 on the weight seat 143 and / or the cantilever 142 through threads to limit the swing of the weight assembly 14, so that the passage 111 is locked in the closed state, and the check valve 1 has the isolation function. Moreover, the bolt and the positioning pin are simple in structure, easy to manufacture and obtain. When the bolt or the positioning pin is installed, it only needs to be inserted into the locking hole 151, without complex operation and professional tools, so that the installation difficulty is reduced. In the later maintenance, if the locking assembly 15 has a problem, the bolt or the positioning pin can be directly rotated out to replace a new bolt or positioning pin.

[0040] Specifically, as shown in Figures 3-4 The check valve 1 further includes a transmission plate 16, the valve leaf 12 is provided in plurality, and the connecting rod assembly 13 is provided in plurality of groups. One end of one group of the connecting rod assembly 13 is connected to the weight assembly 14, and one end of the remaining connecting rod assemblies 13 is connected to the transmission plate 16.

[0041] In this embodiment, each valve leaf 12 is fixed on the passage 111 by a set of link assemblies 13, one end of which is connected to the weight assembly 14, and the other end of the remaining link assemblies 13 is connected to the transmission plate 16. When the airflow flows in the forward direction along the outlet direction, the airflow acts on the valve leaf 12 to push the valve leaf 12 to rotate, the set of link assemblies 13 connected to the weight assembly 14 will drive the cantilever 142 of the weight assembly 14 to swing, at the same time, the link assemblies 13 connected to the transmission plate 16 will transmit the rotating motion of the valve leaf 12 to the transmission plate 16, and the transmission plate 16 will drive the other valve leaf 12 to rotate synchronously through the link assemblies 13 connected thereto, so as to realize the simultaneous opening of the plurality of valve leaves 12; when the airflow flows in the reverse direction along the outlet direction, the valve leaf 12 begins to rotate in the reverse direction under the action of the gravity of the weight assembly 14 and its own gravity, and similarly, through the transmission of the link assemblies 13 and the transmission plate 16, the plurality of valve leaves 12 will be closed synchronously. Through the connection and transmission action of the transmission plate 16, the plurality of valve leaves 12 can be ensured to be opened and closed synchronously. When the plurality of valve leaves 12 are closed synchronously, the adjacent valve leaves 12 are in close contact with each other, reducing the possibility of medium leakage. The closing action of each valve leaf 12 is coordinated through the link assemblies 13 and the transmission plate 16, so that all valve leaves 12 can be closed tightly at the same time, thereby enhancing the overall sealing performance of the check valve 1 and ensuring that the check valve 1 can effectively prevent the medium from flowing backward in the closed state of the passage 111. The weight assembly 14 can be connected to any link assembly 13, and the specific link assembly 13 to be connected is designed according to the specific scene.

[0042] Specifically, as shown in Figure 4 Each set of link assemblies 13 includes a link 131 and a link seat 132, the link seat 132 is arranged outside the valve body 11, one end of the link 131 passes through the inner wall of the valve body 11 and is connected to the link seat 132, the other end of the link 131 passes through the valve leaf 12 and is connected to the other inner wall of the valve body 11, and each link seat 132 is connected by the transmission plate 16.

[0043] In the embodiment, the connecting rod seats 132 are fixedly installed on the outer side walls of the valve body 11 by means of bolts or welding, and the connecting rod seats 132 on one side wall are independently connected, and the connecting rod seats 132 on the other side wall are connected through the transmission plate 16. The transmission plate 16 is connected with the connecting rod seats 132 by means of bolts or pins, so that the transmission plate 16 can effectively transmit the movement between the connecting rod assemblies 13. The connecting rod seats 132 are provided with connecting rod holes, one end of the connecting rod 131 is connected with the connecting rod hole of the connecting rod seat 132 through the inner wall of the valve body 11, and the valve leaf 12 is provided with a connecting hole in the length direction, and the other end of the connecting rod 131 is connected with the other inner wall of the valve body 11 through the connecting hole, so as to fix the valve leaf 12 on the passage 111. The connecting rod seats 132 are connected through the transmission plate 16, so that the plurality of valve leaves 12 can be synchronously opened and closed, and the working efficiency and stability of the check valve 1 are improved.

[0044] Specifically, one end of one connecting rod 131 also passes through the weight seat 143 and is connected with the cantilever 142.

[0045] In the embodiment, one end of one connecting rod 131 protrudes from the connecting rod hole and passes through the first shaft hole of the weight seat 143 and the second shaft hole of the cantilever 142 and is connected with the cantilever 142. When the valve leaf 12 rotates, the connecting rod 131 drives the cantilever 142 to rotate, thereby driving the weight 141 to swing. The direct connection between the connecting rod 131 and the cantilever 142 ensures the movement coordination between the valve leaf 12, the connecting rod assembly 13 and the weight assembly 14. The rotation of the valve leaf 12 can be synchronously transmitted to the weight assembly 14, so that the swing of the weight 141 is consistent with the movement of the valve leaf 12, avoiding the movement lag or inconsistency, and ensuring the smoothness of the opening and closing process of the passage 111.

[0046] Specifically, as shown in Figure 4 The valve leaf 12 is provided with a sealing element 17 at the end.

[0047] In the embodiment, the sealing element 17 is made of rubber material, and the sealing element 17 is wrapped on the end of the valve leaf 12, or a groove is arranged on the end of the valve leaf 12, and the sealing element 17 is located in the groove and protrudes from the groove. When the passage 111 is closed, the adjacent sealing elements 17 abut against each other, so that there is no gap between the adjacent valve leaves 12, and the sealing effect of the passage 111 is enhanced.

[0048] Specifically, when the airflow disappears, the valve leaf 12 rotates under the gravity of the weight assembly 14 to close the passage 111.

[0049] In this embodiment, when the airflow disappears, the valve vane 12 is no longer pushed by the airflow, and the counterweight 141 begins to descend under the action of gravity. The descent of the counterweight 141 causes the cantilever 142 to rotate in the opposite direction around the counterweight seat 143. The rotation of the cantilever 142 is transmitted to the valve vane 12 through the connecting rod assembly 13, causing the valve vane 12 to rotate in the opposite direction until the valve vane 12 completely closes the channel 111. During the closing process of the valve vane 12, in order to ensure the sealing effect, the sealing elements 17 provided at the end of the valve vane 12 are tightly fitted together to prevent the medium from flowing back.

[0050] like Figure 5 As shown, this embodiment of the present invention also provides a ventilation system 2, including the check valve 1 as described above.

[0051] In this embodiment, by providing a locking component 15 on the check valve 1, the check valve 1 can achieve the isolation function without the need to install an additional isolation valve, which reduces the number of valves required to be installed on the ventilation system 2, and allows the ventilation system to have sufficient space to install the check valve 1.

[0052] Specifically, such as Figure 5 As shown, the ventilation system 2 also includes multiple fans 21 arranged in parallel and a static pressure box 22. The static pressure box 22 is connected to the air outlet of multiple fans 21. Multiple check valves 1 are provided, and each check valve 1 is correspondingly set between each fan 21 and the static pressure box 22.

[0053] In existing ventilation systems, such as Figure 1 As shown, there are three fans 20 connected in parallel. Each fan 20 has an isolation valve 10 at its inlet and a check valve 30 at its outlet. The isolation valve 10 remains open during normal operation. When a fan 20 malfunctions and requires maintenance, its corresponding isolation valve 10 is closed to isolate the medium for maintenance. The check valve 30 prevents airflow from flowing back into the outlet of the fan in the static pressure box 40, thus reversing the operation of the fan 20 in standby mode. This embodiment simplifies the design of valves (isolation valves 10 and check valves 30) in existing ventilation systems, requiring only one check valve 1 with isolation function between the outlet (air outlet) of each fan 21 and the static pressure box 22. This design reduces the number of valves, saves construction costs, and reduces operation and maintenance work, thereby solving the layout difficulties in application scenarios with limited space.

[0054] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A check valve having an isolating function, characterized by comprising: 1) a valve body (1) having a valve hole (2) and a valve seat (3) formed in the valve hole (2), The check valve comprises a valve body, a valve leaf, a connecting rod assembly and a weight assembly, the valve body has a passage, the valve leaf is arranged in the passage, the connecting rod assembly is arranged on the side wall of the valve body, and two ends of the connecting rod assembly are connected with the valve leaf and the weight assembly respectively, when air flows, the valve leaf rotates under the action of air flow and drives the weight assembly to swing through the connecting rod assembly to open or close the passage. The check valve further comprises a locking assembly arranged on the weight assembly, and the locking assembly is used for locking the weight assembly when the passage is closed. The weight assembly comprises a weight, a cantilever and a weight seat, the weight seat is installed outside the valve body, one end of the cantilever is rotatably connected to the weight seat, the other end of the cantilever is connected to the weight, and the weight seat and / or the cantilever is provided with a locking hole, and the locking assembly is connected in the locking hole.

2. The check valve of claim 1, wherein The locking assembly is a bolt or a positioning pin.

3. The check valve of claim 2, wherein The check valve further comprises a transmission plate, the valve leaf is provided in plurality, the connecting rod assembly is provided in plurality, one end of one of the connecting rod assemblies is connected to the weight assembly, and the other ends of the remaining connecting rod assemblies are connected to the transmission plate.

4. The check valve of claim 2, wherein Each of the connecting rod assemblies comprises a connecting rod and a connecting rod seat, the connecting rod seat is arranged outside the valve body, one end of the connecting rod is connected to the connecting rod seat through the inner wall of the valve body, and the other end of the connecting rod is connected to the other inner wall of the valve body through the valve leaf, and the connecting rod seats are connected through the transmission plate.

5. The check valve of claim 4, wherein One end of the connecting rod is further connected to the cantilever through the weight seat.

6. The check valve of claim 5, wherein The valve leaf is provided with a sealing element at the end.

7. The check valve of claim 1, wherein When the air flow disappears, the valve leaf rotates under the action of gravity of the weight assembly to close the passage.

8. The check valve of claim 1, wherein The check valve comprises a valve body, a valve leaf, a connecting rod assembly and a weight assembly, the valve body has a passage, the valve leaf is arranged in the passage, the connecting rod assembly is arranged on the side wall of the valve body, and two ends of the connecting rod assembly are connected with the valve leaf and the weight assembly respectively, when air flows, the valve leaf rotates under the action of air flow and drives the weight assembly to swing through the connecting rod assembly to open or close the passage.

9. A ventilation system, characterized in that The check valve further comprises a locking assembly arranged on the weight assembly, and the locking assembly is used for locking the weight assembly when the passage is closed.

10. The vent system of claim 9, wherein, The weight assembly comprises a weight, a cantilever and a weight seat, the weight seat is installed outside the valve body, one end of the cantilever is rotatably connected to the weight seat, the other end of the cantilever is connected to the weight, and the weight seat and / or the cantilever is provided with a locking hole, and the locking assembly is connected in the locking hole. The locking assembly is a bolt or a positioning pin. The check valve further comprises a transmission plate, the valve leaf is provided in plurality, the connecting rod assembly is provided in plurality, one end of one of the connecting rod assemblies is connected to the weight assembly, and the other ends of the remaining connecting rod assemblies are connected to the transmission plate. Each of the connecting rod assemblies comprises a connecting rod and a connecting rod seat, the connecting rod seat is arranged outside the valve body, one end of the connecting rod is connected to the connecting rod seat through the inner wall of the valve body, and the other end of the connecting rod is connected to the other inner wall of the valve body through the valve leaf, and the connecting rod seats are connected through the transmission plate. One end of the connecting rod is further connected to the cantilever through the weight seat. The valve leaf is provided with a sealing element at the end. When the air flow disappears, the valve leaf rotates under the action of gravity of the weight assembly to close the passage. The check valve comprises a valve body, a valve leaf, a connecting rod assembly and a weight assembly, the valve body has a passage, the valve leaf is arranged in the passage, the connecting rod assembly is arranged on the side wall of the valve body, and two ends of the connecting rod assembly are connected with the valve leaf and the weight assembly respectively, when air flows, the valve leaf rotates under the action of air flow and drives the weight assembly to swing through the connecting rod assembly to open or close the passage. The check valve further comprises a locking assembly arranged on the weight assembly, and the locking assembly is used for locking the weight assembly when the passage is closed. The weight assembly comprises a weight, a cantilever and a weight seat, the weight seat is installed outside the valve body, one end of the cantilever is rotatably connected to the weight seat, the other end of the cantilever is connected to the weight, and the weight seat and / or the cantilever is provided with a locking hole, and the locking assembly is connected in the locking hole. The locking assembly is a bolt or a positioning pin. The check valve further comprises a transmission plate, the valve leaf is provided in plurality, the connecting rod assembly is provided in plurality, one end of one of the connecting rod assemblies is connected to the weight assembly, and the other ends of the remaining connecting rod assemblies are connected to the transmission plate. Each of the connecting rod assemblies comprises a connecting rod and a connecting rod seat, the connecting rod seat is arranged outside the valve body, one end of the connecting rod is connected to the connecting rod seat through the inner wall of the valve body, and the other end of the connecting rod is connected to the other inner wall of the valve body through the valve leaf, and the connecting rod seats are connected through the transmission plate. One end of the connecting rod is further connected to the cantilever through the weight seat. The valve leaf is provided with a sealing element at the end. When the air flow disappears, the valve leaf rotates under the action of gravity of the weight assembly to close the passage.

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