A gas pressure stick with built-in overpressure protection valve

Abstract

The utility model provides a kind of gas pressure rod of built-in overvoltage protection valve, comprising: sleeve;Piston cylinder, piston cylinder is set in sleeve, piston cylinder is communicated with sleeve;Piston piece, piston piece is movably set in piston cylinder;Pressure relief valve, pressure relief valve is connected with piston cylinder, pressure relief valve is used to release gas in piston cylinder, by integrated setting a special pressure relief valve on the piston cylinder of gas pressure rod, a controlled pressure relief passage is provided for entire gas pressure rod system, the scheme changes the "passive protection" concept of traditional gas pressure rod into "active protection", when the pressure in piston cylinder is increased to dangerous threshold due to various abnormal conditions, pressure relief valve can be triggered and actively opened, high-pressure gas is rapidly released to the outside, thereby actively and reliably avoiding the serious safety accidents of burst or component flying out caused by pressure accumulation exceeding cylinder limit, greatly improve the intrinsic safety level of product.

Description

Technical Field

[0001] This utility model relates to the field of pneumatic rod manufacturing technology, specifically to a pneumatic rod with a built-in overpressure protection valve. Background Technology

[0002] In gas springs (also known as gas rods), widely used in office chairs, medical chairs, industrial lifting equipment, and car seats, the core function is to utilize the compressibility of high-pressure nitrogen gas in a sealed cylinder to achieve support force output and stepless height adjustment. However, as a pressure-bearing sealed container, gas springs are susceptible to abnormal increases in internal pressure or seal failure under conditions such as long-term use, high-temperature environments, or manufacturing defects. Once the pressure exceeds the withstand limit of the cylinder material, it may cause safety accidents such as bursting or high-speed ejection of piston parts. Although the probability of such accidents is low, the consequences are serious. There have been numerous reports of personal injuries caused by inferior or aged gas springs both domestically and internationally. Currently, most gas springs on the market are fully enclosed structures without pressure release mechanisms. Even if some products pass safety tests, their safety mainly relies on material strength and manufacturing process reliability, which is a form of "passive protection." Once extreme working conditions are encountered (such as internal grease decomposition producing gas or excessive nitrogen filling), the internal pressure rises sharply, and there is a lack of effective active pressure relief methods, so safety hazards still exist.

[0003] Therefore, existing technologies need further development. Utility Model Content

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a pneumatic rod with a built-in overpressure protection valve to solve the technical problem in related technologies where the cylinder pressure rises sharply when the pneumatic rod encounters extreme working conditions (such as internal grease decomposition and gas generation, excessive nitrogen filling, etc.), lacks an effective active pressure relief path, and safety hazards still exist.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution: a pneumatic rod with a built-in overpressure protection valve is provided, comprising: a sleeve; a piston cylinder, the piston cylinder being disposed inside the sleeve and communicating with the sleeve; a piston element, the piston element being movably disposed inside the piston cylinder; and a pressure relief valve, the pressure relief valve being connected to the piston cylinder and used to release gas inside the piston cylinder.

[0006] Furthermore, the pressure relief valve includes: a pressure relief cylinder, which is threaded through a sleeve and connected to a piston cylinder; a pressure relief port located outside the sleeve is provided on the pressure relief cylinder; and a pressure relief piston, which is movably disposed inside the pressure relief cylinder; wherein, when the pressure relief piston moves to a preset position away from the piston cylinder inside the pressure relief cylinder, the pressure relief port communicates with the piston cylinder through the interior of the pressure relief cylinder, so that the gas inside the piston cylinder is released through the pressure relief port.

[0007] Furthermore, the pressure relief valve also includes: a cover body, which is detachably connected to the end of the pressure relief cylinder away from the piston cylinder; a pressure relief spring, which is disposed inside the pressure relief cylinder, with its two ends connected to the pressure relief piston and the cover body respectively; and a telescopic rod, which is located inside the pressure relief spring, with its two ends connected to the pressure relief piston and the cover body respectively, for guiding the pressure relief spring.

[0008] Furthermore, the pressure relief valve also includes a limiting screw, which is threadedly connected to the cover and its end extends into the pressure relief cylinder to limit the extreme position of the pressure relief piston moving away from the piston cylinder.

[0009] Furthermore, the pressure relief valve also includes a limit nut, which is threadedly connected to the limit screw and pressed against the side of the cover away from the pressure relief piston to lock the limit screw.

[0010] Furthermore, the piston component includes a movable piston and a piston rod, with the piston rod connected to the movable piston; the movable piston divides the piston cylinder into an upper air chamber and a lower air chamber; the pneumatic rod also includes a first sealing block and a second sealing block, which are respectively and sealingly disposed at both ends of the piston cylinder.

[0011] Furthermore, the first sealing block has a first air passage that connects the upper air chamber with the inside of the sleeve; the second sealing block has a second air passage that connects the lower air chamber with the inside of the sleeve; when the moving piston moves toward the first sealing block, the gas in the upper air chamber can flow to the lower air chamber through the first air passage and the inside of the sleeve.

[0012] Furthermore, the pneumatic rod also includes a vent valve, which is installed in the first air passage to control the opening and closing of the first air passage.

[0013] Furthermore, the vent valve includes: a conical plug located on the side of the first sealing block near the movable piston; a movable rod connected to the conical plug, located within the first air passage and protruding from the first sealing block; a limiting plate located at the end of the movable rod away from the conical plug; and a return spring sleeved on the movable rod, with both ends of the return spring connected to the limiting plate and the first sealing block, respectively.

[0014] Furthermore, the vent valve also includes: a trigger rod, which passes through the sleeve and is connected to the side of the limiting plate away from the return spring; wherein, when the trigger rod moves toward the first sealing block, the conical plug disengages from the first air passage, so that the sleeve communicates with the upper air chamber.

[0015] Beneficial effects: 1. By integrating a dedicated pressure relief valve into the piston cylinder of the pneumatic rod, a controlled pressure relief channel is provided for the entire pneumatic rod system. This solution transforms the traditional "passive protection" concept of pneumatic rods into "active protection." When the internal pressure of the piston cylinder rises to a dangerous threshold due to various abnormal operating conditions, the pressure relief valve can be triggered and actively opened to quickly release the high-pressure gas to the outside. This proactively and reliably avoids serious safety accidents caused by pressure accumulation exceeding the cylinder limit, such as bursting or component ejection, greatly improving the inherent safety level of the product.

[0016] 2. By setting a pressure relief spring, an adjustable initial preload is provided to the pressure relief piston, thereby precisely setting the opening pressure threshold of the pressure relief valve. The pressure relief process will only start when the pressure inside the piston cylinder is sufficient to overcome the spring preload, effectively preventing malfunction. The telescopic rod passes through the pressure relief spring, providing precise radial guidance for the compression and rebound process of the pressure relief spring, effectively preventing the pressure relief spring from deflecting, jamming, or becoming unstable during operation, ensuring the linearity of the pressure relief piston movement and the repeatability of the action. At the same time, the detachable connection of the cover also provides convenience for the maintenance and replacement of the internal components of the pressure relief valve.

[0017] 3. By rotating the limiting screw that is threaded with the cover, the depth of its end extending into the pressure relief cylinder can be precisely adjusted. This structure sets a mechanical stop, limiting the maximum stroke of the pressure relief piston to move backward during the pressure relief process. This solution achieves precise control over the size of the pressure relief channel opening, thereby adjusting the pressure relief flow rate and speed, avoiding excessive backward retraction of the pressure relief piston that could lead to difficulty in returning to its original position or structural damage, and ensuring the stability and controllability of the pressure relief process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the pneumatic rod with a built-in overpressure protection valve used in this embodiment of the utility model; Figure 2 This is a cross-sectional schematic diagram of the pneumatic rod with a built-in overpressure protection valve used in an embodiment of this utility model; Figure 3 This utility model embodiment uses a pneumatic rod with a built-in overpressure protection valve. Figure 2 Enlarged view of point A in the image; Figure 4 This embodiment of the invention uses a device with a pressure relief valve. Figure 2 Enlarged view of point B in the image.

[0019] The above figures include the following reference numerals: 1. Sleeve; 2. Piston cylinder; 3. Piston component; 4. Pressure relief valve; 5. Pressure relief cylinder; 6. Pressure relief port; 7. Pressure relief piston; 8. Cover; 9. Pressure relief spring; 10. Telescopic rod; 11. Limiting screw; 12. Limiting nut; 13. Moving piston; 14. Piston rod; 15. Upper air chamber; 16. Lower air chamber; 17. First sealing block; 18. Second sealing block; 19. Vent valve; 20. Conical plug; 21. Moving rod; 22. Limiting plate; 23. Return spring; 24. Trigger rod. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0021] According to an embodiment of this utility model, a pneumatic rod with a built-in overpressure protection valve is provided. Please refer to [link / reference]. Figures 1 to 4 It includes: a sleeve 1; a piston cylinder 2, which is disposed inside the sleeve 1 and is connected to the sleeve 1; a piston element 3, which is movably disposed inside the piston cylinder 2; and a pressure relief valve 4, which is connected to the piston cylinder 2 and is used to release gas inside the piston cylinder 2.

[0022] By adopting the above technical solution, a dedicated pressure relief valve 4 is integrated into the piston cylinder 2 of the pneumatic rod, providing a controlled pressure relief channel for the entire pneumatic rod system. This solution transforms the traditional "passive protection" concept of pneumatic rods into "active protection". When the gas pressure inside the piston cylinder 2 rises to a dangerous threshold due to various abnormal operating conditions, the pressure relief valve 4 can be triggered and actively opened to quickly release the high-pressure gas to the outside. This proactively and reliably avoids serious safety accidents caused by pressure accumulation exceeding the cylinder limit, such as bursting or component ejection, greatly improving the inherent safety level of the product.

[0023] Please refer to Figure 1 and Figure 3 The pressure relief valve 4 includes: a pressure relief cylinder 5, which passes through a sleeve 1 and is threadedly connected to a piston cylinder 2; a pressure relief port 6 located outside the sleeve 1 is provided on the pressure relief cylinder 5; and a pressure relief piston 7, which is movably disposed inside the pressure relief cylinder 5; wherein, when the pressure relief piston 7 moves away from the piston cylinder 2 inside the pressure relief cylinder 5 to a preset position, the pressure relief port 6 communicates with the piston cylinder 2 through the inside of the pressure relief cylinder 5, so that the gas in the piston cylinder 2 is released through the pressure relief port 6.

[0024] By adopting the above technical solution, the pressure relief cylinder 5 is directly threaded to the piston cylinder 2, establishing a stable pressure relief path. The pressure relief piston 7, as the core moving component, directly controls the opening and closing of the pressure relief channel. When the pressure inside the cylinder is sufficient to drive the pressure relief piston 7 to overcome the initial resistance and move away from the piston cylinder 2 to a specific position, the previously closed pressure relief channel is opened, and the high-pressure gas can flow through the inside of the pressure relief cylinder 5 and the pressure relief port 6 in sequence to be discharged. This mechanical structure realizes the automatic triggering and rapid response of the pressure relief process, ensuring that the pressure can be released immediately when there is an abnormality, with a rapid response and reliable operation.

[0025] Furthermore, to improve the sealing effect, a flexible film can be wrapped around the threaded portion of the pressure relief cylinder 5 to enhance the sealing effect.

[0026] Please refer to Figure 3 The pressure relief valve 4 also includes: a cover 8, which is detachably connected to the end of the pressure relief cylinder 5 away from the piston cylinder 2; a pressure relief spring 9, which is disposed inside the pressure relief cylinder 5, with its two ends connected to the pressure relief piston 7 and the cover 8 respectively; and a telescopic rod 10, which is located inside the pressure relief spring 9, with its two ends connected to the pressure relief piston 7 and the cover 8 respectively, for guiding the pressure relief spring 9.

[0027] By adopting the above technical solution, and by setting the pressure relief spring 9, an adjustable initial preload is provided for the pressure relief piston 7, thereby accurately setting the opening pressure threshold of the pressure relief valve 4. The pressure relief process will only start when the pressure inside the piston cylinder 2 is sufficient to overcome the spring preload, effectively preventing malfunction. The telescopic rod 10 passes through the inside of the pressure relief spring 9, providing precise radial guidance for the compression and rebound process of the pressure relief spring 9, effectively preventing the pressure relief spring 9 from deflecting, jamming, or becoming unstable during operation, ensuring the linearity of the movement of the pressure relief piston 7 and the repeatability of the action. At the same time, the detachable connection of the cover 8 also provides convenience for the maintenance and replacement of the internal components of the pressure relief valve 4.

[0028] Please refer to Figure 3 The pressure relief valve 4 also includes a limiting screw 11, which is threadedly connected to the cover 8 and its end extends into the pressure relief cylinder 5 to limit the pressure relief piston 7 from moving away from the piston cylinder 2 to the extreme position.

[0029] By adopting the above technical solution, the depth of its end extending into the pressure relief cylinder 5 can be precisely adjusted by rotating the limiting screw 11 that is threaded with the cover 8. This structure sets a mechanical stop, limiting the maximum stroke of the pressure relief piston 7 to move backward during the pressure relief process. This solution achieves precise control of the opening size of the pressure relief channel, thereby adjusting the pressure relief flow rate and speed, avoiding excessive backward retraction of the pressure relief piston 7 that could lead to difficulty in returning to its original position or structural damage, and ensuring the stability and controllability of the pressure relief process.

[0030] Please refer to Figure 3 The pressure relief valve 4 also includes a limit nut 12, which is threadedly connected to the limit screw 11 and pressed against the side of the cover 8 away from the pressure relief piston 7, for locking the limit screw 11.

[0031] By adopting the above technical solution, a limiting nut 12 is set on the limiting screw 11 and pressed against the outside of the cover 8. The friction between the threaded pairs reliably locks the limiting screw 11 in the adjusted position. This solution effectively prevents the limiting screw 11 from spontaneously rotating and loosening during equipment vibration or long-term use, ensuring that the stroke limit of the pressure relief piston 7 set by the limiting screw 11 can remain stable for a long time, thereby maintaining the constant and reliable performance parameters of the pressure relief valve 4.

[0032] Please refer to Figure 2 The piston component 3 includes a movable piston 13 and a piston rod 14, with the piston rod 14 connected to the movable piston 13; the movable piston 13 divides the piston cylinder 2 into an upper air chamber 15 and a lower air chamber 16; the air pressure rod also includes a first sealing block 17 and a second sealing block 18, which are respectively sealed at both ends of the piston cylinder 2.

[0033] By adopting the above technical solution, the moving piston 13 precisely divides the inner cavity of the piston cylinder 2 into an upper air chamber 15 and a lower air chamber 16 that are not connected to each other, forming the core pressure zone for the pneumatic rod to realize the damping or support function. The first sealing block 17 and the second sealing block 18 reliably seal the piston cylinder 2 from both ends, jointly maintaining the integrity of the entire high-pressure airtight environment. This solution provides a basic and reliable pressure vessel structure and functional basis for the pneumatic rod, ensuring its support and buffering performance under normal working conditions.

[0034] Please refer to Figure 2 The first sealing block 17 has a first air passage that connects the upper air chamber 15 with the inside of the sleeve 1; the second sealing block 18 has a second air passage that connects the lower air chamber 16 with the inside of the sleeve 1; when the moving piston 13 moves toward the first sealing block 17, the gas in the upper air chamber 15 can flow to the lower air chamber 16 through the first air passage and the inside of the sleeve 1.

[0035] By adopting the above technical solution, by setting a first air passage and a second air passage on the first sealing block 17 and the second sealing block 18 respectively, and using the internal space of the sleeve 1 as a connecting channel, a controlled gas flow path is established between the upper air chamber 15 and the lower air chamber 16. When the piston rod 14 is compressed and drives the moving piston 13 to move, for example, when it moves toward the first sealing block 17, the volume of the upper air chamber 15 decreases, and the gas inside it can be smoothly replenished to the lower air chamber 16 with an increased volume through the first air passage, the internal space of the sleeve 1 and the second air passage. This solution realizes the orderly transfer of gas and pressure balance between the two air chambers, and provides a structural guarantee for the gas pressure rod to achieve a stable and controllable compression stroke.

[0036] Please refer to Figure 2 The air pressure rod also includes: an air valve 19, which is provided in the first air passage to control the opening and closing of the first air passage.

[0037] By adopting the above technical solution and setting a dedicated ventilation valve 19 in the first air passage, the simple gas passage is upgraded into a controllable on / off interface. This solution makes the connection between the upper air chamber 15 and the sleeve 1 no longer always open, but can be actively cut off or opened as needed. This adds an additional functional control dimension to the pneumatic rod, such as enabling self-locking, rapid lifting and lowering, or damping force adjustment under different working conditions, which greatly enhances the functionality and applicability of the product.

[0038] Please refer to Figure 4 The vent valve 19 includes: a conical plug 20 located on the side of the first sealing block 17 near the moving piston 13; a moving rod 21 connected to the conical plug 20, located in the first air passage and protruding from the first sealing block 17; a limiting plate 22 disposed at the end of the moving rod 21 away from the conical plug 20; and a return spring 23 sleeved on the moving rod 21, with both ends of the return spring 23 connected to the limiting plate 22 and the first sealing block 17, respectively.

[0039] By adopting the above technical solution, the preload of the return spring 23 continuously pushes the limiting plate 22 and the moving rod 21, causing the conical plug 20 to be tightly pressed against the valve seat of the first sealing block 17. This reliably seals the first air passage under normal conditions, cutting off the connection between the upper air chamber 15 and the sleeve 1, and realizing the self-locking function of the pneumatic rod. The moving rod 21 provides precise guidance for the conical plug 20, ensuring its alignment with the valve seat and sealing effect. The limiting plate 22 provides a stable force application plane for the return spring 23 and restricts the initial position of the moving rod 21 and the conical plug 20 in the direction of the spring force. This solution constitutes a normally closed valve body with simple structure, reliable operation, and excellent sealing performance.

[0040] Please refer to Figure 4The vent valve 19 further includes a trigger rod 24, which passes through the sleeve 1 and is connected to the side of the limiting plate 22 away from the reset spring 23; wherein, when the trigger rod 24 moves toward the first sealing block 17, the conical plug 20 disengages from the first air passage, so that the sleeve 1 communicates with the upper air chamber 15.

[0041] By adopting the above technical solution, by setting a trigger rod 24 connected to the limiting plate 22 and extending the trigger rod 24 to the outside of the sleeve 1, an external mechanical operation interface is provided for opening the internal ventilation valve 19. When the trigger rod 24 is pushed by external force, it can directly overcome the resistance of the return spring 23 and drive the conical plug 20 to move, thereby forcibly opening the first air passage closed by the conical plug 20. This solution realizes the active and reliable release of the self-locking state of the pneumatic rod, so that the user or the actuator can control the pneumatic rod to enter the ventilation state through a simple linear thrust operation when needed, and realize height adjustment or other functions. The operation is direct and the response is rapid.

[0042] Working principle: During the working process, when the pneumatic rod is in normal working condition, the pressure relief valve 4 remains closed, and the pressure relief piston 7 blocks the pressure relief channel under the preload of the pressure relief spring 9. At this time, if the piston rod 14 is subjected to downward pressure, the moving piston 13 moves downward in the piston cylinder 2, the volume of the upper air chamber 15 decreases, and the volume of the lower air chamber 16 increases. The gas in the upper air chamber 15 slowly exchanges with the inside of the sleeve 1 through the gap or specific channel around the vent valve 19 on the first sealing block 17 (which is normally closed and sealed by the return spring 23 pressing the conical plug 20), generating a damping effect. When the system experiences abnormally high pressure, the gas pressure in the piston cylinder 2... The force overcomes the preload of the pressure relief spring 9, pushing the pressure relief piston 7 to move away from the piston cylinder 2 until the pressure relief port 6 connects with the piston cylinder 2 through the inside of the pressure relief cylinder 5, and the high-pressure gas is then quickly discharged from the pressure relief port 6; the maximum stroke of the pressure relief piston 7 can be adjusted by rotating the limit screw 11, thereby controlling the pressure relief rate, and the adjustment position is locked by the limit nut 12; when the seat height needs to be adjusted normally, the user operates the trigger rod 24, pushes the limit plate 22 to compress the reset spring 23, drives the conical plug 20 to disengage from the valve seat, opens the first air passage, and connects the upper air chamber 15 with the sleeve 1, so that the piston rod 14 can move freely to achieve lifting and lowering adjustment.

[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0044] Optionally, specific examples in this embodiment can refer to the examples described in the above embodiments, and will not be repeated here.

[0045] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0046] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0047] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A pneumatic rod with a built-in overpressure protection valve, characterized in that, include: Sleeve (1); Piston cylinder (2), the piston cylinder (2) is disposed inside the sleeve (1), and the piston cylinder (2) is connected to the sleeve (1); Piston component (3), which is movably disposed within the piston cylinder (2); Pressure relief valve (4) is connected to piston cylinder (2) and is used to release gas in piston cylinder (2).

2. The pneumatic rod with a built-in overpressure protection valve according to claim 1, characterized in that, The pressure relief valve (4) includes: Pressure relief cylinder (5), the pressure relief cylinder (5) passes through the sleeve (1) and is threadedly connected to the piston cylinder (2); the pressure relief cylinder (5) has a pressure relief port (6) located outside the sleeve (1). A pressure relief piston (7) is movably disposed within the pressure relief cylinder (5); When the pressure relief piston (7) moves to a preset position in the pressure relief cylinder (5) away from the piston cylinder (2), the pressure relief port (6) communicates with the piston cylinder (2) through the inside of the pressure relief cylinder (5) so that the gas in the piston cylinder (2) is released through the pressure relief port (6).

3. The pneumatic rod with a built-in overpressure protection valve according to claim 2, characterized in that, The pressure relief valve (4) also includes: The cover (8) is detachably connected to the end of the pressure relief cylinder (5) away from the piston cylinder (2); A pressure relief spring (9) is disposed inside the pressure relief cylinder (5), and the two ends of the pressure relief spring (9) are respectively connected to the pressure relief piston (7) and the cover (8); Telescopic rod (10) is located inside the pressure relief spring (9). The two ends of the telescopic rod (10) are connected to the pressure relief piston (7) and the cover (8) respectively, and are used to provide guidance for the pressure relief spring (9).

4. The pneumatic rod with a built-in overpressure protection valve according to claim 3, characterized in that, The pressure relief valve (4) also includes: A limiting screw (11) is threaded to the cover (8) and its end extends into the pressure relief cylinder (5) to limit the pressure relief piston (7) from moving away from the piston cylinder (2) to the extreme position.

5. The pneumatic rod with a built-in overpressure protection valve according to claim 4, characterized in that, The pressure relief valve (4) also includes: A limiting nut (12) is threadedly connected to the limiting screw (11) and pressed against the side of the cover (8) away from the pressure relief piston (7) to lock the limiting screw (11).

6. The pneumatic rod with a built-in overpressure protection valve according to claim 1, characterized in that, The piston component (3) includes a movable piston (13) and a piston rod (14), the piston rod (14) being connected to the movable piston (13); the movable piston (13) divides the piston cylinder (2) into an upper air chamber (15) and a lower air chamber (16); the air pressure rod also includes a first sealing block (17) and a second sealing block (18), the first sealing block (17) and the second sealing block (18) being respectively sealed at both ends of the piston cylinder (2).

7. The pneumatic rod with a built-in overpressure protection valve according to claim 6, characterized in that, The first sealing block (17) has a first air passage that connects the upper air chamber (15) with the inside of the sleeve (1); the second sealing block (18) has a second air passage that connects the lower air chamber (16) with the inside of the sleeve (1); when the moving piston (13) moves toward the first sealing block (17), the gas in the upper air chamber (15) can flow to the lower air chamber (16) through the first air passage and the inside of the sleeve (1).

8. The pneumatic rod with a built-in overpressure protection valve according to claim 7, characterized in that, The pneumatic rod also includes: Ventilation valve (19): A ventilation valve (19) is provided in the first air passage to control the opening and closing of the first air passage.

9. The pneumatic rod with a built-in overpressure protection valve according to claim 8, characterized in that, The vent valve (19) includes: A conical plug (20) is located on the side of the first sealing block (17) near the movable piston (13); The movable rod (21) is connected to the conical plug (20), and the movable rod (21) is located in the first air passage and protrudes from the first sealing block (17). A limiting plate (22) is disposed at one end of the moving rod (21) away from the conical plug (20); A reset spring (23) is sleeved on the moving rod (21), and the two ends of the reset spring (23) are respectively connected to the limiting plate (22) and the first sealing block (17).

10. The pneumatic rod with a built-in overpressure protection valve according to claim 9, characterized in that, The vent valve (19) further includes a trigger rod (24), which passes through the sleeve (1) and is connected to the side of the limiting plate (22) away from the return spring (23); When the trigger rod (24) moves toward the first sealing block (17), the conical plug (20) disengages from the first air passage, so that the sleeve (1) communicates with the upper air chamber (15).

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