A closed natural gas leak detection device

Abstract

The application provides a closed natural gas leakage detection device, which comprises a detection tube, a cover plate fixed at the top end of the detection tube, a shaft rod penetrating into the detection tube through the cover plate, a natural gas detector installed on the shaft rod, a screw rod fixed at the lower end of the shaft rod, a nut seat connected to the screw rod, a bottom plate fixed in the detection tube, the bottom plate being rotationally assembled with the bottom end of the screw rod, and a guide structure arranged between the nut seat and the detection tube; an inner sealing sleeve is fixed on the inner wall of the detection tube, an outer sealing sleeve is fixed outside the nut seat, the outer sealing sleeve has a separation position for sealingly cooperating with the inner sealing sleeve to separate the detection tube into an upper cavity and a lower cavity, and the outer sealing sleeve has a communication position for communicating the upper cavity and the lower cavity after moving downward. In use, the outer sealing sleeve is at the communication position, if natural gas leaks, the natural gas floats from the lower cavity to the upper cavity and is concentrated in the detection tube, so that the natural gas detector can conveniently detect the concentration, and the natural gas concentration detection result is ensured to be accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas leakage detection, and particularly relates to a closed natural gas leakage detection device. BACKGROUND

[0002] At present, most of the extraction and transportation stations adopt multi-well underground gathering and transportation process, and there are many underground process pipelines. After years of use, the pipelines may be corroded and leak. The ground of the extraction and transportation station is hardened by cement, and the natural gas leakage cannot be discovered in time, which exists a safety hazard.

[0003] In view of this, the Chinese utility model patent with the authorization announcement number CN208687371U discloses a natural gas extraction and transportation station underground pipeline leakage detection window. A plurality of detection tubes are arranged above the natural gas underground pipeline, and a cover is arranged above the detection tubes. The user needs to open the cover, monitor the inside of the detection tube through a natural gas detection instrument, analyze the natural gas concentration in the plurality of detection tubes, find the area closest to the leakage point with the highest concentration, and immediately implement a leakage repair measure to avoid dangerous accidents.

[0004] Although the above-mentioned patent has a simple structure, the cover above the detection tube needs to be opened for monitoring. If the natural gas underground pipeline leaks seriously, the density of the natural gas is less than that of the air after the cover is opened, and the natural gas floats upwards. This not only causes the concentration measured by the natural gas detector to be unstable and the detection result to be inaccurate, but also causes the natural gas with high concentration to run out of the detection tube. If a naked flame is encountered, a dangerous safety accident is more likely to occur. SUMMARY

[0005] The present application aims to provide a closed natural gas leakage detection device to solve the problem of inaccurate natural gas concentration detection result in the prior art.

[0006] To achieve the above-mentioned purpose, the closed natural gas leakage detection device in the present application adopts the following technical scheme:

[0007] The utility model provides a closed natural gas leakage detection device, which comprises a detection tube arranged above a natural gas pipeline underground, a cover plate fixedly arranged at the top end of the detection tube, a shaft rod penetrating through the cover plate and extending into the detection tube, a natural gas detector arranged on the shaft rod for detecting the concentration of natural gas in the detection tube, a screw rod fixedly arranged at the lower end of the shaft rod, a nut seat threadedly connected to the screw rod, a bottom plate fixedly arranged in the detection tube, a through space between the bottom plate and the detection tube for natural gas to pass through, the bottom end of the screw rod being rotatably assembled to the bottom plate, a guide structure arranged between the nut seat and the detection tube for guiding the up-down movement of the nut seat, an inner sealing sleeve fixedly arranged on the inner wall of the detection tube, an outer sealing sleeve fixedly arranged on the outer surface of the nut seat for moving up and down synchronously with the nut seat, the outer sealing sleeve having a separation position in the inner hole of the inner sealing sleeve and being in sealing cooperation with the inner sealing sleeve so as to separate the inner cavity of the detection tube into an upper cavity and a lower cavity, the natural gas detector being arranged in the upper cavity, and the outer sealing sleeve further having a communication position for moving downward and separating from the inner sealing sleeve so as to make the upper cavity and the lower cavity communicate.

[0008] The natural gas detector is arranged on the shaft rod, the shaft rod penetrates through the cover plate and extends into the detection tube, the lower end of the shaft rod is fixedly arranged with the screw rod, the nut seat is threadedly connected to the screw rod, the bottom end of the screw rod is rotatably assembled to the bottom plate, the guide structure is arranged between the nut seat and the detection tube for guiding the up-down movement of the nut seat, and thus a screw nut mechanism is formed, when the shaft rod is rotated, the nut seat can only move up and down along the screw rod under the action of the guide structure, and thus the outer sealing sleeve fixedly arranged on the outer surface of the nut seat moves up and down synchronously.

[0009] When the natural gas detector is not needed to be detected, the outer sealing sleeve is arranged at the separation position, the upper cavity and the lower cavity are isolated, even if natural gas leaks, the natural gas is also concentrated in the lower cavity and cannot overflow the detection tube, when the natural gas detector needs to be detected, the outer sealing sleeve is arranged at the communication position, if natural gas leaks, the density of the natural gas is smaller than that of air, the natural gas floats from the lower cavity to the upper cavity, the top end of the detection tube is fixedly arranged with the cover plate, and thus the natural gas is concentrated in the detection tube, the concentration detection of the natural gas detector is facilitated, and the detection result of the natural gas concentration is ensured to be accurate.

[0010] Further, a through hole penetrating through the shaft rod is arranged in the shaft rod, the natural gas detector is arranged at the lower end of the through hole, and the upper end of the through hole forms a wire outlet hole for the top end of the natural gas detector to connect to an electric wire.

[0011] The beneficial effects of the above technical solutions are that the installation and outlet of the natural gas detector are facilitated.

[0012] Further, a fixing frame is fixed on the outer surface of the lower end of the shaft rod, the bottom end of the fixing frame is lower than the bottom end of the natural gas detector, and the fixing frame is fixedly connected with the upper end of the screw rod.

[0013] The beneficial effects of the above technical solutions are that the fixing connection between the shaft rod and the screw rod is facilitated, and the detection function of the natural gas detector is ensured not to be affected.

[0014] Further, the upper end of the screw rod is fixed with a top plate, the fixing frame comprises at least two L-shaped fixing rods, the horizontal edges of the fixing rods are fixedly connected with the outer surface of the lower end of the shaft rod, and the vertical edges of the fixing rods are fixedly connected with the top plate.

[0015] The beneficial effects of the above technical solutions are that the fixing frame has a simple structure, and the manufacturing and installation of the fixing frame are facilitated, and the top plate fixed on the upper end of the screw rod facilitates the fixing connection with the fixing frame.

[0016] Further, the guide structure comprises a limiting rod fixed on the nut seat and a limiting slide rail fixed on the inner wall of the detection pipe, the limiting slide rail is located below the inner sealing sleeve, and the limiting rod and the limiting slide rail are guided in the up-down direction.

[0017] The beneficial effects of the above technical solutions are that the guide structure is facilitated to be set, manufactured and used.

[0018] Further, the shaft rod is provided with an exhaust hole extending upward and downward, the lower end of the exhaust hole is communicated with the upper cavity, the upper end of the exhaust hole is located above the cover plate, and a sealing cover is installed at the upper end of the exhaust hole.

[0019] The beneficial effects of the above technical solutions are that if natural gas leaks, the leaked gas is facilitated to be discharged from the detection pipe through the exhaust hole, the exhaust is facilitated to be controlled through the installation of the sealing cover, and the safety is improved.

[0020] Further, the top end of the shaft rod is installed with an electric control box electrically connected with the natural gas detector.

[0021] The beneficial effects of the above technical solutions are that the work of the natural gas detector is facilitated to be controlled.

[0022] Further, a limiting ring is sleeved on the shaft rod, the limiting ring is located above the cover plate, the limiting ring and the shaft rod are guided in the up-down direction, a downward extending plug plate is fixed on the limiting ring, a limiting vertical plate is fixed on the cover plate, and an elastic member is connected between the shaft rod and the limiting ring, so that the plug plate is limited between the two limiting vertical plates.

[0023] The beneficial effects of the above technical solution are that when the shaft does not need to rotate, the plug plate is limited between the two limiting vertical plates, which can prevent the limiting ring from rotating and further prevent the shaft from rotating; when the shaft needs to rotate, the limiting ring is lifted up, the plug plate is away from the limiting vertical plate, the limiting ring can be rotated, thereby driving the shaft to rotate, and the control is convenient and the shaft can be prevented from being rotated by mistake.

[0024] Further, the shaft is externally fixed with a fixed plate, the fixed plate is located above the cover plate, the elastic member is a spring, the upper end of the spring is connected to the limiting ring, and the lower end of the spring is connected to the fixed plate.

[0025] The beneficial effects of the above technical solution are that the configuration and installation of the elastic member are facilitated.

[0026] Further, the limiting vertical plates are arranged in a radial manner, and the cross section of the plug plate is in a fan shape.

[0027] The beneficial effects of the above technical solution are that the plug plate and the limiting vertical plate are facilitated to cooperate. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a schematic view of the installation position of the closed natural gas leakage detection device in the application;

[0029] Figure 2 It is a structural view of the closed natural gas leakage detection device in the application;

[0030] Figure 3 It is a structural view of the shaft of the closed natural gas leakage detection device in the application;

[0031] Figure 4 It is a top view of the cover plate of the closed natural gas leakage detection device in the application.

[0032] In the figure: 100, closed natural gas leakage detection device; 1, natural gas pipeline; 2, detection pipe; 3, shaft; 4, natural gas detector; 5, top plate; 6, screw rod; 7, bottom plate; 8, inner sealing sleeve; 9, nut seat; 10, outer sealing sleeve; 11, limiting rod; 12, limiting sliding rail; 13, cover plate; 14, limiting vertical plate; 15, plug plate; 16, limiting ring; 17, fixed plate; 18, sliding groove; 19, sliding block; 20, electric control box; 21, sealing cover; 22, through hole; 23, exhaust hole; 24, fixed frame; 25, spring. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given to the present application in combination with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application, i.e., the described examples are only a part of the examples of the present application, but not all the examples. The components of the embodiments of the present application generally described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0034] Therefore, the detailed description of the embodiments of the present application provided in the accompanying drawings below is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative labor are within the scope of protection of the present application.

[0035] It should be noted that the relationship terms such as "first" and "second" and the like that can appear are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or sequence between the entities or operations. Moreover, terms such as "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the elements defined by the statement "including a" and the like do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0036] The features and performances of the present application will be further described in detail below in combination with the examples.

[0037] Embodiment 1 of the enclosed natural gas leakage detection device in the present application is shown in Figure 1 The natural gas pipeline 1 is buried underground, and the enclosed natural gas leakage detection device 100 includes a detection pipe 2 arranged above the natural gas pipeline 1. In combination with Figure 2 The top end of the detection pipe 2 is sealingly and fixedly installed with a cover plate 13, and the enclosed natural gas leakage detection device 100 further includes a shaft rod 3 penetrating into the detection pipe 2 through the cover plate 13, and a natural gas detector 4 for detecting the concentration of natural gas in the detection pipe 2 is installed on the shaft rod 3. Specifically, as Figure 3As shown, the shaft 3 is provided with a through hole 22 extending through the shaft 3 from top to bottom, the natural gas detector 4 is installed at the lower end of the through hole 22, in order to ensure the sealing and avoid the leaked natural gas in the detection tube 2 flowing into the through hole 22, a sealing ring is arranged between the natural gas detector 4 and the shaft 3, and the sealing ring is sleeved on the outside of the natural gas detector 4 during installation, and then the natural gas detector 4 is installed into the through hole 22. The upper end of the through hole 22 constitutes a wire outlet hole for connecting the top end of the natural gas detector 4, and the top end of the shaft 3 is provided with an electric control box 20, the electric control box 20 is electrically connected with the wire at the top end of the natural gas detector 4, and is used for controlling the working of the natural gas detector 4.

[0038] As shown in Figure 2 and Figure 3 , the lower end of the shaft 3 is fixedly provided with a screw rod 6, and specifically, Figure 2 , the upper end of the screw rod 6 is fixedly provided with a top plate 5, and the fixed frame 24 includes two L-shaped fixed rods, the horizontal edges of the fixed rods are fixedly connected with the outer surface of the lower end of the shaft 3, and the vertical edges of the fixed rods are fixedly connected with the top plate 5, so as to realize the fixed connection between the shaft 3 and the screw rod 6 and ensure that the detection function of the natural gas detector 4 is not affected.

[0039] A bottom plate 7 is fixedly arranged in the detection tube 2, and the bottom end of the screw rod 6 is rotatably assembled on the bottom plate 7 through a bearing. The bottom plate 7 and the detection tube 2 have a through space for natural gas to pass through, and specifically, the bottom plate 7 is a strip-shaped plate, or the bottom plate 7 is a circular plate, but the bottom plate 7 is provided with a through hole for natural gas to pass through, so as to ensure that the bottom plate 7 does not block the detection tube 2.

[0040] As shown in Figure 2 , the screw rod 6 is threadedly connected with a nut seat 9, and a guide structure for guiding the up-down movement of the nut seat 9 is arranged between the nut seat 9 and the detection tube 2, and specifically, the guide structure includes a limiting rod 11 fixed on the nut seat 9 and a limiting slide rail 12 fixed on the inner wall of the detection tube 2, the limiting rod 11 and the limiting slide rail 12 are guided and matched in the up-down direction (rotation is stopped in the circumferential direction), and the limiting rod 11 and the limiting slide rail 12 are respectively provided with two, which are symmetrically arranged. In this way, a screw nut mechanism is formed, and when the shaft 3 is rotated, the nut seat 9 can only move up and down along the screw rod 6 under the limitation of the guide structure.

[0041] As shown in Figure 2As shown, the inner wall of the detection tube 2 is fixed with an inner sealing sleeve 8, the inner sealing sleeve 8 is above the limiting slide rail 12, the outer part of the nut seat 9 is fixed with an outer sealing sleeve 10 for synchronous up and down movement with the nut seat 9, the up and down movement of the outer sealing sleeve 10 has two stations, which are a separation position in the inner hole of the inner sealing sleeve 8 and in sealing cooperation with the inner sealing sleeve 8 to separate the inner cavity of the detection tube 2 into an upper cavity and a lower cavity, that is, an upper position; At the same time, it also has a communication position which moves downward to separate from the inner sealing sleeve 8 to make the upper cavity and the lower cavity communicate, that is, a lower position. The natural gas detector 4 is located in the upper cavity, when it is not necessary to detect, the outer sealing sleeve 10 is in the upper position, the upper cavity and the lower cavity are isolated, even if the natural gas leaks, it will not overflow the detection tube 2. When it is necessary to detect, the outer sealing sleeve 10 is in the lower position, if the natural gas leaks, the density of the natural gas is less than the density of the air, then the natural gas floats from the lower cavity to the upper cavity, because the top end of the detection tube 2 is sealingly and fixedly installed with a cover plate 13, therefore the natural gas is concentrated in the detection tube 2, which is convenient for the natural gas detector 4 to detect the concentration, and ensures the accuracy of the natural gas concentration detection result.

[0042] When detecting that the natural gas leaks, in order to facilitate the natural gas to be discharged, Figure 3 As shown, the side wall of the shaft rod 3 is provided with an exhaust hole 23 extending upward and downward, the lower end hole of the exhaust hole 23 communicates with the upper cavity, the upper end hole of the exhaust hole 23 is above the cover plate 13 and a sealing cover 21 is installed at the upper end hole, by opening the sealing cover 21, the leaked natural gas can be concentrated and collected, so as to avoid that the high-concentration natural gas is discharged to the outside and meets the open flame to cause a safety accident.

[0043] In order to facilitate the rotation of the shaft rod 3 and prevent misoperation, a limiting ring 16 is sleeved on the shaft rod 3, the limiting ring 16 is above the cover plate 13, the limiting ring 16 and the shaft rod 3 are guided and matched in the up and down direction, specifically, the upper part of the outer periphery of the shaft rod 3 is provided with a sliding groove 18, the inner wall of the limiting ring 16 is provided with a sliding block 19, the sliding block 19 is embedded in the sliding groove 18 and guided and matched with the sliding groove 18 in the up and down direction (it is rotationally stopped in the circumferential direction). The limiting ring 16 is fixed with a downward extending plug plate 15, the cover plate 13 is fixed with a limiting vertical plate 14, the shaft rod 3 and the limiting ring 16 are connected with an elastic member, so that the plug plate 15 is limited between the two limiting vertical plates 14. Specifically, the outer part of the shaft rod 3 is fixed with a fixed plate 17, the fixed plate 17 is above the cover plate 13, the above-mentioned elastic member is a spring 25, the upper end of the spring 25 is connected to the limiting ring 16, and the lower end is connected to the fixed plate 17.

[0044] In this way, when the shaft 3 does not need to rotate, the plug plate 15 is limited between the two limiting vertical plates 14, which can prevent the limiting ring 16 from rotating, and further prevent the shaft 3 from rotating; when the shaft 3 needs to rotate, the limiting ring 16 is lifted, the spring 25 is stretched, the plug plate 15 is away from the limiting vertical plate 14, and the limiting ring 16 can be rotated, thereby driving the shaft 3 to rotate, which is convenient to control and can prevent the shaft 3 from being misrotated. At the same time, as shown in Figure 4 the limiting vertical plate 14 is provided with a plurality of and arranged in a radial manner, and the cross section of the plug plate 15 is in a fan shape. In this way, when the limiting ring 16 is rotated by a certain angle, the plug plate 15 can be very conveniently inserted between the corresponding two limiting vertical plates 14, and the effect of preventing misrotation is continuously maintained.

[0045] The working principle of the closed natural gas leakage detection device in the application is as follows:

[0046] When not detected, the outer sealing sleeve 10 is in an upper position, which isolates the upper cavity and the lower cavity. When detection is needed, the limiting ring 16 is lifted, and then the limiting ring 16 is rotated, thereby driving the shaft 3 to rotate. Under the principle of the screw nut mechanism, the nut seat 9 and the outer sealing sleeve 10 are synchronously moved downward, the outer sealing sleeve 10 is completely separated from the inner sealing sleeve 8, the upper cavity and the lower cavity are communicated, the gas in the detection tube 2 is uniformly mixed, the natural gas detector 4 starts to detect under the control of the electric control box 20, the concentration of the natural gas in the detection tube 2 is obtained, and since the natural gas is concentrated in the detection tube 2, the detection result of the natural gas concentration can be ensured to be accurate. If natural gas leakage occurs at this position, the user can open the sealing cover 21, and the leaked natural gas is discharged along the exhaust hole 23, so that the leaked natural gas can be concentrated and collected, and direct overflow is avoided to avoid safety accidents caused by encountering open fire.

[0047] Embodiment 2 of the closed natural gas leakage detection device in the application: different from embodiment 1, only two limiting vertical plates are provided, and the cross section of the plug plate is a rectangle, and in this case, the limiting ring can only be rotated to a specific position to enable the plug plate to be inserted between the two limiting vertical plates.

[0048] Embodiment 3 of the closed natural gas leakage detection device in the application: different from embodiment 1, the elastic member is not a spring, but a rubber band, the upper end of the rubber band is connected to the limiting ring, and the lower end of the rubber band is connected to the shaft.

[0049] Embodiment 4 of the closed natural gas leakage detection device in the application: different from embodiment 1, the limiting ring and the elastic member are not provided, and in this case, the effect of preventing misrotation is not achieved.

[0050] Embodiment 5 of the closed natural gas leakage detection device in the application: different from embodiment 1, the shaft top end is not provided with the electric control box, and the electric wire at the top end of the natural gas detector is led out and then connected to other control equipment.

[0051] Embodiment 6 of the closed natural gas leakage detection device in the application: different from embodiment 1, no exhaust hole is arranged in the shaft rod.

[0052] Embodiment 7 of the closed natural gas leakage detection device in the application: different from embodiment 1, the guide structure between the nut seat and the detection tube is a guide rod fixed on the nut seat and a guide groove directly arranged on the inner wall of the detection tube, and the guide rod and the guide groove are in up-down guide cooperation.

[0053] Embodiment 8 of the closed natural gas leakage detection device in the application: different from embodiment 1, the upper end of the screw rod is not fixed with the top plate, but a transversely extending horizontal plate is arranged at the lower end of the fixing frame, the horizontal plate is fixedly connected with the screw rod, and the fixing frame is not an L-shaped fixing rod.

[0054] Embodiment 9 of the closed natural gas leakage detection device in the application: different from embodiment 1, no fixing frame is fixed on the outer surface of the lower end of the shaft rod, the upper end of the screw rod is directly fixed with the shaft rod, the upper end of the screw rod is provided with a cavity, the detection head of the natural gas detector extends into the cavity, and a communication hole communicating with the cavity is arranged on the cavity wall, so as to facilitate the detection of the natural gas detector.

[0055] Embodiment 10 of the closed natural gas leakage detection device in the application: different from embodiment 1, no through hole penetrating through the shaft rod is arranged in the shaft rod, and the natural gas detector is fixed on the outer surface of the shaft rod, and at this time, the outlet hole can be arranged on the cover plate.

[0056] Embodiment 11 of the closed natural gas leakage detection device in the application: different from embodiment 1, the screw rod and the shaft rod are integrally arranged.

[0057] The above is only the preferred embodiment of the application, and is not used to limit the application, the patent protection scope of the application is subject to the claims, and any equivalent structural changes made by referring to the content of the specification and drawings of the application should be included in the protection scope of the application.

Claims

1. A closed-loop natural gas leak detection device, comprising a detection pipe (2) for installation above an underground natural gas pipeline (1), characterized in that: A cover plate (13) is fixedly installed at the top of the detection tube (2). The closed natural gas leak detection device also includes a shaft (3) that extends through the cover plate (13) into the detection tube (2). A natural gas detector (4) for detecting the concentration of natural gas in the detection tube (2) is installed on the shaft (3). A screw (6) is fixedly or integrally provided at the lower end of the shaft (3). A nut seat (9) is threadedly connected to the screw (6). A base plate (7) is fixedly provided inside the detection tube (2). There is a passage space between the base plate (7) and the detection tube (2) for natural gas to pass through. The bottom end of the screw (6) is rotatably mounted on the base plate (7). The nut seat (9) A guide structure is provided between the probe tube (2) and the nut seat (9) for guiding the up and down movement of the nut seat (9); an inner sealing sleeve (8) is fixed on the inner wall of the probe tube (2), and an outer sealing sleeve (10) is fixed on the outside of the nut seat (9) for moving up and down synchronously with the nut seat (9). The outer sealing sleeve (10) has a partition position that is located in the inner hole of the inner sealing sleeve (8) and seals with the inner sealing sleeve (8) to divide the inner cavity of the probe tube (2) into an upper cavity and a lower cavity. The natural gas detector (4) is located in the upper cavity. The outer sealing sleeve (10) also has a communication position that moves downward and disengages from the inner sealing sleeve (8) to make the upper cavity and the lower cavity communicate.

2. The closed-loop natural gas leak detection device according to claim 1, characterized in that: The shaft (3) has a through hole (22) that runs through the shaft (3) from top to bottom. The natural gas detector (4) is installed at the lower end of the through hole (22). The upper end of the through hole (22) forms an outlet hole for the wire connected to the top of the natural gas detector (4).

3. The closed-loop natural gas leak detection device according to claim 2, characterized in that: A fixing bracket (24) is fixed on the outer surface of the lower end of the shaft (3). The bottom end of the fixing bracket (24) is lower than the bottom end of the natural gas detector (4). The fixing bracket (24) is fixedly connected to the upper end of the screw (6).

4. The closed-loop natural gas leak detection device according to claim 3, characterized in that: The upper end of the screw (6) is fixed with a top plate (5), and the fixing frame (24) includes at least two L-shaped fixing rods. The horizontal side of the fixing rod is fixedly connected to the outer surface of the lower end of the shaft (3), and the vertical side of the fixing rod is fixedly connected to the top plate (5).

5. The closed-loop natural gas leak detection device according to any one of claims 1 to 4, characterized in that: The guide structure includes a limiting rod (11) fixed on the nut seat (9) and a limiting slide rail (12) fixed on the inner wall of the probe tube (2). The limiting slide rail (12) is located below the inner sealing sleeve (8), and the limiting rod (11) and the limiting slide rail (12) are guided and cooperated in the vertical direction.

6. The closed-loop natural gas leak detection device according to any one of claims 1 to 4, characterized in that: The shaft (3) is provided with an exhaust hole (23) extending vertically. The lower end of the exhaust hole (23) is connected to the upper cavity. The upper end of the exhaust hole (23) is located above the cover plate (13) and a sealing cover (21) is installed at the upper end of the hole.

7. The closed-loop natural gas leak detection device according to any one of claims 1 to 4, characterized in that: The top of the shaft (3) is equipped with an electrical control box (20) that is electrically connected to the natural gas detector (4).

8. The closed-loop natural gas leak detection device according to any one of claims 1 to 4, characterized in that: A limiting ring (16) is fitted on the shaft (3). The limiting ring (16) is located above the cover plate (13). The limiting ring (16) and the shaft (3) are guided and fitted in the vertical direction. A downwardly extending insert plate (15) is fixed on the limiting ring (16). A limiting plate (14) is fixed on the cover plate (13). An elastic element is connected between the shaft (3) and the limiting ring (16) so that the insert plate (15) is limited between the two limiting plates (14).

9. The closed-loop natural gas leak detection device according to claim 8, characterized in that: A fixing plate (17) is fixed to the outside of the shaft (3). The fixing plate (17) is located above the cover plate (13). The elastic element is a spring (25). The upper end of the spring (25) is connected to the limiting ring (16), and the lower end of the elastic element is connected to the fixing plate (17).

10. The closed-loop natural gas leak detection device according to claim 8, characterized in that: The limiting upright plate (14) is provided in multiple radial arrangement, and the cross-section of the insert plate (15) is fan-shaped.

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