Safety well lid

Abstract

The utility model discloses a safety well lid, which belongs to the technical field of underground pipeline maintenance and comprises a well lid main body, a ventilation component and a gas detection component. Wherein the well lid main body is arranged at a well mouth of a shaft in an openable and closable manner; the ventilation assembly comprises a supporting column and fan blades, the supporting column is vertically arranged in the middle of the shaft, the fan blades are arranged on the periphery of the supporting column and located at the position close to the wellhead, and the fan blades can rotate around the supporting column to form a circular barrier face used for plugging the wellhead; the gas detection component is arranged in the shaft and is in signal connection with the ventilation assembly, and the gas detection component is used for detecting the concentration value of harmful gas in the shaft and controlling the fan blades to rotate or stop based on the concentration value of the harmful gas. Through cooperation of the ventilation assembly and the gas detection component, intelligent and automatic operation is achieved, the operation safety and efficiency are improved, the detection function, the protection function and the ventilation function are organically combined, the operation efficiency is improved, and the underground operation safety is effectively guaranteed in time.

Description

Technical Field

[0001] This utility model relates to the field of underground pipeline maintenance technology, and in particular to a safety manhole cover. Background Technology

[0002] With the rapid development of modern urban construction, underground tunnel networks are becoming increasingly dense, and the use of underground space for various municipal engineering, power and communication engineering and other construction operations is constantly increasing, and well drilling operations are becoming more and more frequent.

[0003] In traditional well-opening operations, poisoning accidents occur frequently due to a lack of standardized and effective safety measures. The underground environment is typically enclosed, easily accumulating toxic and harmful gases such as carbon monoxide and hydrogen sulfide. These gases can originate from various sources, including sewage, pipeline leaks, and microbial fermentation. If construction workers fail to accurately assess the underground gas environment and implement effective ventilation before starting well-opening operations, they are highly likely to inhale toxic gases, leading to poisoning or even endangering their lives.

[0004] Most existing manhole covers only provide basic functions such as covering the well opening and preventing accidental falls, without any design for detecting and ventilating the underground gas environment. This forces construction workers to rely on relatively primitive and inaccurate detection methods when opening wells, such as using simple gas detection equipment or judging the underground gas conditions based on experience, which cannot fundamentally ensure the safety of the working environment.

[0005] To prevent underground poisoning accidents and effectively protect the personal safety of construction workers, it is urgent to develop a new type of safety manhole cover. Utility Model Content

[0006] The purpose of this utility model is to provide a safety manhole cover to solve the technical problem in the prior art that there is a lack of devices for accurately detecting and effectively ventilating the underground gas environment before well opening operations, which leads to workers being prone to inhaling toxic gases.

[0007] Based on the above concept, the technical solution adopted by this utility model is as follows:

[0008] A safety manhole cover, comprising:

[0009] The main body of the manhole cover is closable and installed at the opening of the manhole.

[0010] A ventilation assembly includes a support column and fan blades. The support column is vertically disposed in the middle of the shaft, and the fan blades are disposed on the outer periphery of the support column and located near the shaft opening. The fan blades are capable of rotating around the support column to form a circular barrier surface for sealing the shaft opening.

[0011] A gas detection component is installed inside the well shaft and is signal-connected to the ventilation assembly. The gas detection component is used to detect the concentration of harmful gases inside the well shaft and control the fan blades to rotate or stop based on the concentration of harmful gases.

[0012] Preferably, the ventilation assembly further includes an adjustment mechanism disposed at the connection between the fan blade and the support column. The adjustment mechanism is used to drive the fan blade to rotate along the axial direction of the support column, so that the fan blade switches between an extended state and a retracted state.

[0013] When the fan blades are in the unfolded state, the fan blades are perpendicular to the support column, and the fan blades can rotate around the support column to form the circular barrier surface;

[0014] When the fan blades are in the contracted state, the fan blades are parallel to the support column and are contracted to the outer wall of the support column, and a clearance space is formed between the fan blades and the inner wall of the well shaft.

[0015] Preferably, the outer diameter of the circular barrier surface is smaller than the inner diameter of the wellbore and is greater than or equal to two-thirds of the inner diameter of the wellbore.

[0016] Preferably, the fan blades are provided in two parts, and the two fan blades are symmetrically arranged on both sides of the support column.

[0017] Preferably, the safety manhole cover further includes a support platform, which is disposed on the manhole opening. A connecting port is provided through the middle of the support platform, and the connecting port is coaxially disposed with the manhole opening. A positioning protrusion is formed inside the connecting port, and the manhole cover body can be mounted on the positioning protrusion for closing the manhole opening.

[0018] Preferably, the outer edge of the manhole cover body protrudes along its own thickness direction to form an extension, which is used to be mounted on the positioning protrusion. When the extension is mounted on the positioning protrusion, the top of the manhole cover body and the top of the support platform are located on the same horizontal plane.

[0019] Preferably, an annular protrusion is formed in the middle of the main body of the manhole cover, and a plurality of reinforcing ribs are formed between the annular protrusion and the extension, with the plurality of reinforcing ribs arranged at intervals along the circumference of the annular protrusion.

[0020] Preferably, a fall-prevention net is provided between the wellhead and the fan blades.

[0021] Preferably, the safety manhole cover further includes a display component disposed outside the manhole opening. The display component is signal-connected to the ventilation component and the gas detection component, and is used to display the concentration value of the harmful gas and the working status of the ventilation component.

[0022] Preferably, the safety manhole cover further includes a warning component, which includes a flashing light and a speaker. The warning component is signal-connected to the gas detection component, and the gas detection component signal can control the flashing light and speaker to respond or stop based on the concentration value of the harmful gas.

[0023] The beneficial effects of this utility model are:

[0024] The safety manhole cover proposed in this utility model has a closable body installed at the manhole opening to meet the basic requirements of closing and opening the manhole. A support column stands vertically in the middle of the manhole, with fan blades located on the outer perimeter of the support column near the manhole opening. This layout does not occupy excessive manhole space while effectively fulfilling its function. Before opening the cover, a gas detection component monitors the concentration of toxic gases inside the manhole in real time. If the concentration exceeds a safety threshold, the fan blades rotate around the support column to form a circular barrier sealing the manhole opening, preventing operators from accidentally entering the manhole. Simultaneously, the rotating fan blades act as a ventilation fan, using airflow generated by the rotation to expel harmful gases from the manhole, accelerating air circulation, diluting the air inside the manhole, and reducing the concentration of harmful gases. When the concentration of harmful gases drops below the safety threshold, the fan blades stop rotating, and operators can enter the manhole through the gap in the fan blades to carry out subsequent operations. In summary, this safety manhole cover achieves intelligent and automated operation through the coordinated use of ventilation components and gas detection components. It eliminates the need for complex manual judgment and frequent operation, promptly responds to changes in the gas environment inside the manhole, and improves operational safety and efficiency. By organically combining detection, protection, and ventilation functions, it not only improves operational efficiency but also ensures underground operation safety more promptly and effectively compared to traditional manual detection and operation methods. Attached Figure Description

[0025] Figure 1 This is a front view of the safety manhole cover provided in this embodiment of the present invention during the operation of the ventilation assembly;

[0026] Figure 2 This is a top view of the safety manhole cover provided in this embodiment of the present invention during the operation of the ventilation assembly;

[0027] Figure 3 This is a front view of the safety manhole cover provided in this embodiment of the present invention when the ventilation assembly is stopped;

[0028] Figure 4 This is a top view of the safety manhole cover provided in this embodiment of the utility model when the ventilation assembly is stopped.

[0029] In the picture:

[0030] 100. Wellbore; 101. Wellhead;

[0031] 1. Main body of the manhole cover; 11. Extension section; 12. Annular protrusion; 13. Reinforcing rib;

[0032] 2. Ventilation components; 21. Support column; 22. Fan blades;

[0033] 3. Gas detection components;

[0034] 4. Support platform; 41. Connection port; 42. Positioning flange;

[0035] 5. Fall protection net. Detailed Implementation

[0036] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0037] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0038] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] See Figures 1 to 4The safety manhole cover provided in this embodiment includes a manhole cover body 1, a ventilation component 2, and a gas detection component 3. The manhole cover body 1 is closably disposed at the manhole opening 101 of a manhole casing 100. The ventilation component 2 includes a support column 21 and a fan blade 22. The support column 21 is vertically disposed in the middle of the manhole casing 100, and the fan blade 22 is disposed on the outer periphery of the support column 21 and located near the manhole opening 101. The fan blade 22 can rotate around the support column 21 to form a circular barrier surface for sealing the manhole opening 101. The gas detection component 3 is disposed inside the manhole casing 100 and is signal-connected to the ventilation component 2. The gas detection component 3 is used to detect the concentration of harmful gases inside the manhole casing 100 and controls the fan blade 22 to rotate or stop based on the concentration of harmful gases.

[0041] The safety manhole cover proposed in this utility model has a main body 1 that can be opened and closed at the wellhead 101 of the manhole 100 to meet the basic requirements for closing and opening the wellhead 101. A support column 21 stands vertically in the middle of the manhole 100, and fan blades 22 are located on the outer periphery of the support column 21 near the wellhead 101. This layout does not occupy too much space in the manhole 100 while still functioning effectively. Before opening the cover, the gas detection component 3 monitors the concentration of toxic gases inside the manhole 100 in real time. If the concentration of toxic gases exceeds the safety threshold, the fan blades 22 are controlled to rotate around the support column 21 to form a circular barrier surface to block the wellhead 101, preventing operators from accidentally entering the manhole 100. Simultaneously, the rotation of the fan blades 22 acts as a fan for ventilation. Based on the principle of airflow, the airflow generated by the rotation expels harmful gases from the manhole 100, accelerates air circulation, dilutes the air inside the manhole 100, and reduces the concentration of harmful gases inside the manhole 100. When the concentration of harmful gas drops below the safety threshold, the fan blades 22 stop rotating, and the operator can enter the well casing 100 through the fan gap from the wellhead 101 to carry out subsequent operations. In summary, this safety manhole cover achieves intelligent and automated operation through the coordinated cooperation of the ventilation component 2 and the gas detection component 3. It eliminates the need for complex manual judgment and frequent operation, promptly responds to changes in the gas environment inside the well casing 100, improves operational safety and efficiency, and organically combines detection, protection, and ventilation functions. This not only improves operational efficiency but also ensures safer underground operations more promptly and effectively compared to traditional manual detection and operation methods.

[0042] Understandably, in some cases, when the fan blade 22 rotates, the manhole cover body 1 can be fully or partially opened to facilitate air circulation inside and outside the manhole 100 and achieve ventilation. In other cases, multiple ventilation holes can be opened through the manhole cover body 1 so that even without opening the manhole cover body 1, air can circulate through the ventilation holes by rotating the fan blade 22 to achieve the exhaust and ventilation of the gas inside the manhole 100.

[0043] The specific structure of the safety manhole cover is described below.

[0044] The manhole cover body 1 is closably installed at the wellhead 101 of the well shaft 100, used to close and open the wellhead 101. The opening and closing of the manhole cover body 1 can be achieved manually by pulling or pressing, or hydraulically driven by installing a hydraulic cylinder on one side of the well shaft 100, with the piston rod of the cylinder connected to the manhole cover body 1 via a hinge. By controlling the inflow and outflow of hydraulic oil, the piston rod is extended and retracted, thereby achieving the opening and closing of the manhole cover body 1. Further details are omitted here.

[0045] To better achieve the fit between the manhole cover body 1 and the manhole opening 101, the safety manhole cover also includes a support platform 4. The support platform 4 is set on the manhole opening 101, and a connecting port 41 is provided through the middle of the support platform 4. The connecting port 41 is coaxially arranged with the manhole opening 101, and a positioning flange 42 is formed inside the connecting port 41. The manhole cover body 1 can be mounted on the positioning flange 42 for closing the manhole opening 101. The support platform 4 provides a stable load-bearing foundation for the manhole cover body 1. Through the coaxial arrangement of the connecting port 41 through the middle with the manhole opening 101, and the positioning flange 42 formed inside the connecting port 41, a good connection between the manhole cover body 1 and the manhole opening 101 is ensured, avoiding problems such as manhole cover shaking and poor sealing caused by installation deviation. This enhances the stability and sealing of the manhole cover body 1 when closing the manhole opening 101, further preventing debris, rainwater, etc. from entering the manhole casing 100, and protecting the equipment and environment inside the manhole casing 100.

[0046] Preferably, the outer edge of the manhole cover body 1 protrudes along its thickness to form an extension 11. The extension 11 is used to mount on the positioning flange 42. When the extension 11 is mounted on the positioning flange 42, the top of the manhole cover body 1 and the top of the support platform 4 are on the same horizontal plane. The extension 11 increases the contact area between the manhole cover body 1 and the positioning flange 42, making the force on the manhole cover body 1 more evenly distributed when bearing pressure, effectively reducing the risk of cracking or damage to the manhole cover body 1 due to excessive local force. When the extension 11 is mounted on the positioning flange 42, the top of the manhole cover body 1 and the top of the support platform 4 are on the same horizontal plane. From the perspective of road traffic, whether pedestrians or vehicles are walking or driving, they will not experience a bumpy feeling when passing the manhole opening 101 due to the height difference between the manhole cover body 1 and the support platform 4, thus improving the comfort and safety of passage.

[0047] Furthermore, an annular protrusion 12 is formed in the middle of the manhole cover body 1, and multiple reinforcing ribs 13 are formed between the annular protrusion 12 and the extension 11. The multiple reinforcing ribs 13 are arranged at intervals along the circumference of the annular protrusion 12. The annular protrusion 12 can disperse the vertical pressure from the top of the manhole cover body 1, so that it is transmitted more evenly to all parts of the manhole cover body 1. The reinforcing ribs 13 arranged at intervals along the circumference of the annular protrusion 12 further strengthen the structure of the manhole cover body 1 from the center to the outer edge. When the manhole cover is subjected to external forces such as vehicle running over it or heavy object impact, the reinforcing ribs 13 and the annular protrusion 12 work together to effectively prevent the manhole cover body 1 from deforming or cracking, thus extending the service life of the manhole cover.

[0048] The ventilation component 2 includes a support column 21 and a fan blade 22. On the one hand, the fan blade 22 rotates around the support column 21 to form a circular barrier surface to block the well opening 101 and prevent operators from accidentally entering the well shaft 100. On the other hand, the rotation of the fan blade 22 acts as a fan to exhaust air. Based on the principle of air flow, the airflow generated by the rotation will expel harmful gases from the well shaft 100, accelerate air circulation, and dilute the air inside the well shaft 100.

[0049] When the concentration of harmful gas drops below the safety threshold, the fan blade 22 stops rotating. During the process of the operator entering the shaft 100 through the fan gap from the wellhead 101, in order to prevent the fan blade 22 from interfering with the operator's entry and exit from the shaft 100, the ventilation assembly 2 also includes an adjustment mechanism. The adjustment mechanism is located at the connection between the fan blade 22 and the support column 21. The adjustment mechanism is used to drive the fan blade 22 to rotate along the axial direction of the support column 21, so that the fan blade 22 switches between the extended state and the retracted state. When the fan blade 22 is in the extended state, the fan blade 22 is perpendicular to the support column 21, and the fan blade 22 can rotate around the support column 21 to form a circular barrier surface. When the fan blade 22 is in the retracted state, the fan blade 22 is parallel to the support column 21 and retracts to the outer wall of the support column 21, and a clearance space is formed between the fan blade 22 and the inner wall of the shaft 100.

[0050] Specifically, the attitude adjustment mechanism includes an electric actuator and a connecting rod. A connecting seat is provided at the connection between the fan blade 22 and the support column 21. The connecting seat is fixed to the end of the fan blade 22 near the support column 21 and can rotate around a fixed axis connected to the support column 21, thus providing a rotational basis for the fan blade 22 to rotate. One end of the electric actuator is hinged to the support column 21, and the other end is hinged to one end of the connecting rod. The other end of the connecting rod is also hinged to the connecting seat of the fan blade 22.

[0051] When it is necessary to adjust the fan blade 22 from the extended state to the retracted state, the electric push rod begins to retract, and the connecting rod connected to it drives the connecting seat to rotate around the fixed axis, thereby causing the fan blade 22 to rotate around the axis of the support column 21, gradually changing from an extended state perpendicular to the support column 21 to a retracted state parallel to the support column 21, and finally retracting into the outer wall of the support column 21. At this time, a clearance space is formed between the fan blade 22 and the inner wall of the well shaft 100, which facilitates the operation of personnel to enter and exit the well shaft 100.

[0052] Conversely, when the fan blade 22 needs to be switched from the retracted state to the extended state, the electric push rod extends. During the extension of the electric push rod, the connecting seat is pushed to rotate in the opposite direction through the connecting rod, so that the fan blade 22 flips again to a position perpendicular to the support column 21. At this time, the fan blade 22 is in the extended state and can rotate around the support column 21 to form a circular barrier surface, performing the function of ventilation or sealing the wellhead 101.

[0053] In other embodiments, the attitude adjustment mechanism can also be a worm gear reducer fixedly mounted on the support column 21, with the worm driven by a motor. The fan blade 22 is connected to the worm gear. When the motor starts, it drives the worm to rotate, which in turn drives the worm gear to rotate, thereby causing the fan blade 22 connected to it to rotate axially around the support column 21.

[0054] It is understandable that the specific implementation of the attitude adjustment mechanism is not limited here, as long as the above functions can be achieved.

[0055] Specifically, the outer diameter of the circular barrier surface is smaller than the inner diameter of the shaft 100 and greater than or equal to two-thirds of the inner diameter of the shaft 100. This can prevent the outer diameter of the circular barrier surface from being too large, which would cause the fan blade 22 to rub against the inner wall of the shaft 100 during rotation and damage the equipment. It can also prevent the outer diameter of the circular barrier surface from being too small, which would prevent it from providing effective protection, ventilation and air exchange.

[0056] Specifically, two fan blades 22 are provided, symmetrically arranged on both sides of the support column 21. When the fan blades 22 rotate, the airflow generated by the two fan blades 22 cooperates, allowing the air inside the shaft 100 to be more comprehensively and rapidly agitated. At the same time, the symmetrical arrangement of the two fan blades 22 on both sides of the support column 21 ensures that the centrifugal forces generated when the fan blades 22 rotate are balanced. During high-speed rotation, this symmetrical structure can effectively reduce vibration and swaying caused by imbalance of centrifugal forces.

[0057] In other embodiments, a single, three, or four fan blades 22 may be provided and arranged at intervals along the circumference of the support column 21. The number and arrangement of the fan blades 22 are not limited here.

[0058] In addition, to further enhance the safety of the manhole cover, a fall-prevention net 5 is installed between the manhole opening 101 and the fan blade 22. The fall-prevention net 5 provides additional safety protection. Although the fan blade 22 can form a circular barrier to seal the manhole opening 101 when harmful gases exceed the standard, there is still a very small probability of fan blade 22 malfunctioning or personnel forcibly entering. The fall-prevention net 5 acts as a safety net; if someone accidentally falls into the manhole opening 101, the fall-prevention net 5 can catch the falling person, preventing them from falling directly into the manhole casing 100 and causing serious injury or death, thus reducing the risk of safety accidents caused by accidental falls. At the same time, the fall-prevention net 5 can also effectively prevent parts or tools from falling from the manhole opening 101, ensuring the safety of the facilities inside the manhole casing 100.

[0059] The gas detection component 3 is used to detect the concentration of harmful gases inside the wellbore 100, and to control the fan blades 22 to rotate or stop based on the concentration of harmful gases.

[0060] Specifically, the gas detection component 3 includes a sensor group, a signal processor, and a control transmission device. The sensor group includes various sensors for detecting different harmful gases, such as sensors for common downhole harmful gases like carbon monoxide and hydrogen sulfide. The gas concentration information detected by the sensors is transmitted to the signal processor in the form of electrical signals. The signal processor amplifies and filters these electrical signals to remove noise interference and converts them into easily analyzable digital signals. Subsequently, the control transmission device receives the digital signals from the signal processor and compares them with a pre-set safety threshold. If the detected harmful gas concentration is higher than the safety threshold, the control transmission device immediately sends a control signal to the ventilation component 2, causing the fan blades 22 to rotate, performing ventilation and wellhead 101 sealing operations; if the harmful gas concentration is lower than the safety threshold, a signal is sent to stop the fan blades 22 from rotating, allowing operators to safely enter the wellbore 100. Simultaneously, the control transmission device also has data storage and wireless transmission functions, enabling real-time recording and storage of detection data, and uploading it to a remote monitoring terminal via wireless communication, facilitating management personnel to monitor the gas conditions inside the wellbore 100 at any time.

[0061] Specifically, the ventilation assembly 2 also includes a drive component, which comprises a motor, a reducer, a transmission mechanism, and a control circuit. The motor, as a power source, provides the torque required for the fan blades 22 to rotate. The reducer, connected to the motor, reduces the high speed output by the motor and correspondingly increases the torque, ensuring the fan blades 22 receive stable rotational power that meets actual needs. The transmission mechanism transmits the power adjusted by the reducer to the fan blades 22, causing them to rotate around the support column 21. The control circuit is connected to the control transmission device of the gas detection component 3, receiving control signals from the control transmission device to drive the motor and control the fan blades 22 to rotate or stop.

[0062] In addition, the safety manhole cover includes a display component located outside the manhole opening 101. This display component is connected to the ventilation assembly 2 and the gas detection component 3 to display the concentration of harmful gases and the operating status of the ventilation assembly 2. The display component shows the concentration of harmful gases in real time, providing on-site personnel with intuitive and timely information. Workers can clearly determine the safety of the underground gas environment near the manhole opening 101 without the need for additional detection equipment, enabling them to quickly assess whether it is safe to carry out operations, thus improving overall work efficiency and resource utilization.

[0063] Specifically, the display component includes a display screen, which establishes signal connections with the ventilation assembly 2 and the gas detection component 3 via wireless connection. When the detection sensor group in the gas detection component 3 detects the concentration of harmful gas in the shaft 100, and converts it into a digital signal through the signal processing unit and transmits it to the control transmission module, the control transmission module sends the harmful gas concentration value to the display component. Upon receiving the signal, the display component displays the current concentration of harmful gas in the shaft 100 in real time on the display screen using numbers and corresponding gas symbols.

[0064] Similarly, during operation, the motor drive system in ventilation component 2 generates electrical signals that characterize its working status, such as the motor's operating current and speed. These signals are processed and fed back to the display component through signal lines. After receiving these signals, the display component displays the working status of ventilation component 2 on the screen in a graphical or textual manner.

[0065] The safety manhole cover also includes a warning component, which consists of a flashing light and a speaker. The warning component is connected to a gas detection component 3, which controls the flashing light and speaker to respond or stop based on the concentration of harmful gases. Through the cooperation of the warning component and the gas detection component 3, a comprehensive warning signal is promptly and effectively issued to surrounding personnel when the concentration of harmful gases exceeds the standard, thus improving the safety warning effect of the safety manhole cover on the surrounding environment.

[0066] Understandably, the working principles and connection relationships of flashing lights and speakers are common practices in this field and will not be elaborated upon here.

[0067] The above embodiments merely illustrate the basic principles and characteristics of this utility model. This utility model is not limited to the above embodiments. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A safety manhole cover, characterized in that, include: The main body of the manhole cover (1) is closable and installed at the opening (101) of the manhole (100); The ventilation assembly (2) includes a support column (21) and a fan blade (22). The support column (21) is vertically disposed in the middle of the shaft (100). The fan blade (22) is disposed on the outer periphery of the support column (21) and located near the well opening (101). The fan blade (22) can rotate around the support column (21) to form a circular barrier surface for sealing the well opening (101). A gas detection component (3) is installed inside the well shaft (100) and is signal-connected to the ventilation assembly (2). The gas detection component (3) is used to detect the concentration value of harmful gas inside the well shaft (100) and control the fan blade (22) to rotate or stop based on the concentration value of harmful gas.

2. The safety manhole cover according to claim 1, characterized in that, The ventilation assembly (2) further includes an adjustment mechanism, which is located at the connection between the fan blade (22) and the support column (21). The adjustment mechanism is used to drive the fan blade (22) to rotate along the axial direction of the support column (21), so that the fan blade (22) switches between an extended state and a retracted state. When the fan blade (22) is in the unfolded state, the fan blade (22) is perpendicular to the support column (21), and the fan blade (22) can rotate around the support column (21) to form the circular barrier surface; When the fan blade (22) is in a contracted state, the fan blade (22) is parallel to the support column (21) and is contracted to the outer wall of the support column (21), and a clearance space is formed between the fan blade (22) and the inner wall of the well shaft (100).

3. The safety manhole cover according to claim 1, characterized in that, The outer diameter of the circular barrier surface is smaller than the inner diameter of the well shaft (100) and greater than or equal to two-thirds of the inner diameter of the well shaft (100).

4. The safety manhole cover according to claim 1, characterized in that, Two fan blades (22) are provided, and the two fan blades (22) are symmetrically arranged on both sides of the support column (21).

5. The safety manhole cover according to claim 1, characterized in that, The safety manhole cover also includes a support platform (4), which is disposed on the manhole (101). A connecting port (41) is provided in the middle of the support platform (4). The connecting port (41) is coaxially disposed with the manhole (101). A positioning protrusion (42) is formed inside the connecting port (41). The manhole cover body (1) can be mounted on the positioning protrusion (42) for closing the manhole (101).

6. The safety manhole cover according to claim 5, characterized in that, The outer edge of the manhole cover body (1) protrudes along its own thickness direction to form an extension (11). The extension (11) is used to be mounted on the positioning protrusion (42). When the extension (11) is mounted on the positioning protrusion (42), the top of the manhole cover body (1) and the top of the support platform (4) are located on the same horizontal plane.

7. The safety manhole cover according to claim 6, characterized in that, A ring-shaped protrusion (12) is formed in the middle of the main body (1) of the manhole cover. A plurality of reinforcing ribs (13) are formed between the ring-shaped protrusion (12) and the extension (11). The plurality of reinforcing ribs (13) are arranged at intervals along the circumference of the ring-shaped protrusion (12).

8. The safety manhole cover according to any one of claims 1-7, characterized in that, A fall protection net (5) is provided between the wellhead (101) and the fan blade (22).

9. The safety manhole cover according to any one of claims 1-7, characterized in that, The safety manhole cover also includes a display component disposed outside the manhole (101). The display component is connected to the ventilation component (2) and the gas detection component (3) for displaying the concentration value of the harmful gas and the working status of the ventilation component (2).

10. The safety manhole cover according to any one of claims 1-7, characterized in that, The safety manhole cover also includes a warning component, which includes a flashing light and a speaker. The warning component is signal-connected to the gas detection component (3), and the gas detection component (3) can control the flashing light and speaker to respond or stop based on the concentration value of the harmful gas.

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