Lifting mechanism of self-closing valve

Abstract

The lifting mechanism of the self-closing valve comprises a valve cover, a connecting rod, a safety cap, a lifting button and a leather diaphragm, a first sliding hole is formed in the top of the valve cover in a penetrating mode, a connecting sleeve is arranged at the top of the valve cover, the lifting button is detachably connected to the connecting sleeve, an operation part is formed at the bottom of the lifting button, and a second sliding hole is formed in the operation part in a penetrating mode. The operating part is provided with at least one adjusting unit, each adjusting unit comprises an abutting part, an elastic part and an adjusting part, the operating part is provided with a through movable hole for sliding connection of the abutting part, the side wall, close to the connecting rod, of the abutting part is provided with a wear-resistant layer, the outer wall of the operating part is provided with a mounting hole, and the adjusting part is in threaded connection in the mounting hole; the elastic piece is arranged between the adjusting piece and the abutting piece. According to the lifting mechanism of the self-closing valve, it is guaranteed that the connecting rod slides up and down more stably, unnecessary shaking or sliding is reduced, compensation adjustment of the critical pressure value when the air pressure of the self-closing valve is overhigh is achieved, the self-closing valve does not need to be wholly disassembled, and adjustment operation is convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of valves, and particularly relates to a lifting mechanism of a self-closing valve. Background Art

[0002] The pipeline gas self-closing valve, abbreviated as the self-closing valve, is installed on the pipeline of the gas system. When the air pressure in the pipeline is underpressure or overpressure, it can automatically close without electricity or other external power and must be manually opened. The existing lifting mechanism of the gas self-closing valve usually adopts a connecting rod method. For example, the utility model patent with the publication number CN208024891U discloses a pipeline gas self-closing valve, which includes a valve body and an inlet pipe and an outlet pipe arranged at both ends. There is a ball valve on the inlet pipe. A valve cover with a central opening is fixedly connected above the valve body. A valve cover pull rod passes through the center of the valve cover. A lifting mechanism is arranged at the top of the valve cover pull rod. The bottom end of the valve cover pull rod is an iron suction part and is fixedly connected with a diaphragm. The diaphragm and the valve body form a sealed accommodation cavity. A limit frame is fixedly fitted in the accommodation cavity. An iron pressing plate with a central opening is fixed above the limit frame. A magnet is placed above the pressing plate. A transmission mechanism fixedly connected with the magnet is arranged below the pressing plate. A pull cap is connected to the transmission mechanism. When the air pressure in the valve body is overpressure, the diaphragm bulges due to excessive air pressure, so that the valve cover pull rod slides upward to a predetermined position against the suction force of the magnet, ensuring that the suction part of the valve cover pull rod is separated from the magnet. The iron pressing plate moves downward due to its own weight to close the valve body.

[0003] However, after the existing lifting mechanism of the self-closing valve is used for a long time, the sliding movement of the connecting rod is unstable, and it is easy to generate unnecessary shaking or sliding. It is possible that the self-closing valve automatically closes when the air pressure in the valve body does not reach the critical pressure value at overpressure. It is necessary to disassemble and repair the lifting mechanism of the self-closing valve, which is inconvenient to use. Summary of the Utility Model

[0004] The purpose of the utility model is to design a lifting mechanism of a self-closing valve to solve the above technical deficiencies, ensure that the up and down sliding of the connecting rod is smoother, reduce unnecessary shaking or sliding, and realize the compensation adjustment of the critical pressure value when the air pressure of the self-closing valve is overpressure. It is not necessary to disassemble the whole self-closing valve, and the adjustment operation is relatively convenient.

[0005] To solve the above technical problems, the technical solution of the present utility model is: a lifting mechanism of a self-closing valve, including a valve cover, a connecting rod, a safety cap, a lifting knob, and a diaphragm. A first sliding hole for the sliding connection of the connecting rod is penetrated through the top of the valve cover. The end of the connecting rod extending out of the valve cover is fixedly connected to the safety cap. The safety cap is telescopically and cooperatively arranged on the lifting knob. A connecting sleeve is arranged on the top of the valve cover. The lifting knob is detachably connected to the connecting sleeve. The end of the connecting rod extending into the valve cover is fixedly connected to the diaphragm. The periphery of the diaphragm cooperates with the bottom surface of the valve cover. A columnar operating portion is formed at the bottom of the lifting knob. A second sliding hole adapted to and communicating with the first sliding hole is penetrated through the operating portion. The connecting rod is slidably connected within the second sliding hole. At least one adjusting unit is arranged on the operating portion. The adjusting unit includes an abutting member, an elastic member, and an adjusting member. An activity hole for the sliding connection of the abutting member is penetrated through the operating portion. The activity hole communicates with the second sliding hole. A wear-resistant layer is arranged on the side wall of the abutting member close to the connecting rod. The wear-resistant layer abuts against the outer wall of the connecting rod. An installation hole coaxially aligned and communicating with the activity hole is opened on the outer wall of the operating portion. The adjusting member is threadedly connected within the installation hole. The elastic member is arranged between the adjusting member and the abutting member.

[0006] Preferably, a plurality of adjusting units are arranged, and the plurality of adjusting units are uniformly arranged in a circular array.

[0007] Preferably, the adjusting member includes a head and a rod portion. The outer wall of the head is threadedly engaged with the inner wall of the installation hole. An operating groove is opened on the side wall of the head away from the rod portion. The rod portion is inserted and cooperated with the activity hole.

[0008] Preferably, the elastic member is a spring structure. Coaxially aligned first centering portions and second centering portions are respectively arranged on the opposite sides of the rod portion and the abutting member. The two sides of the elastic member are respectively sleeved on the first centering portion and the second centering portion.

[0009] Preferably, at least one positioning groove extending along its axial direction is opened on the inner wall of the activity hole. The abutting member is provided with a positioning portion slidably connected within the positioning groove.

[0010] Preferably, it further includes a connecting cover. The connecting cover is sleeved on the valve cover, and the connecting cover can rotate and move relative to the valve cover. A docking ring is integrally formed at the bottom of the connecting cover. A first connecting ring is arranged on the outer wall of the bottom of the valve cover. The outer wall of the first connecting ring is threadedly engaged with the inner wall of the docking ring. The connecting sleeve is integrally formed on the top of the connecting cover. A connecting groove for the insertion of the operating portion is formed by the cooperation of the inner wall of the connecting sleeve and the top surface of the valve cover. The connecting groove is in interference fit or threaded fit with the operating portion.

[0011] Preferably, a slot for inserting the safety helmet is formed at the top of the lifting knob, a limiting snap spring is arranged on the outer wall of the connecting rod relative to the bottom surface of the safety helmet, and the outer diameter of the limiting snap spring is larger than the inner diameter of the second sliding hole.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0013] The user can separate the lifting knob from the connecting sleeve. By the threaded connection between the adjusting member and the mounting hole, the adjusting member is screwed in or out to accurately change the compression amount of the elastic member, adjust the magnitude of the pre-tightening force of the elasticity, and further change the pressing force of the wear-resistant layer of the abutting member on the outer wall of the connecting rod. The abutting member forms interference in the radial direction of the connecting rod to ensure that the up-and-down sliding of the connecting rod is smoother, reduce unnecessary shaking or sliding, and realize the compensation adjustment of the critical pressure value when the air pressure of the self-closing valve exceeds the pressure. It is not necessary to disassemble the whole self-closing valve, and the adjustment operation is relatively convenient. When the air pressure of the self-closing valve reaches the critical pressure value of overpressure, the connecting rod slides upward to a predetermined position, ensuring that the self-closing valve realizes the function of automatic closing when overpressured, and ensuring the use effect of the self-closing valve. Description of the Drawings

[0014] Figure 1 is a schematic structural diagram of the lifting mechanism in the first embodiment;

[0015] Figure 2 is Figure 1 an enlarged view of area A in

[0016] Figure 3 is a sectional view of the operation part with two adjusting units in the first embodiment;

[0017] Figure 4 is a sectional view of the operation part with three adjusting units in the first embodiment;

[0018] Figure 5 is a sectional view of the self-closing valve in the second embodiment.

[0019] In the figure: 1. valve cover; 101. first sliding hole; 102. first connecting ring; 103. stepped cavity; 2. connecting rod; 201. limit snap ring; 3. safety helmet; 4. lifting knob; 401. operating part; 402. second sliding hole; 403. movable hole; 404. mounting hole; 405. positioning groove; 406. slot; 5. diaphragm; 6. abutting part; 601. wear-resistant layer; 602. second centering part; 603. positioning part; 7. elastic part; 8. adjusting part; 81. head; 82. rod part; 801. operating groove; 802. first centering part; 9. connecting cover; 901. docking ring; 902. connecting sleeve; 10. connecting snap ring; 11. sealing ring; 12. annular pressing piece; 13. first magnet; 14. valve body shell; 1401. intake pipe; 1402. exhaust pipe; 1403. second connecting ring; 1404. gas passage; 15. flow control valve; 16. ball valve switch; 17. guide pipe; 1701. gas passing hole; 18. pressing plate part; 1801. second magnet; 19. limiting structure; 20. through hole; 21. spring part. Detailed implementation mode

[0020] The following further describes the present utility model in conjunction with the accompanying drawings through embodiments.

[0021] Embodiment 1:

[0022] Refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 For a lifting mechanism of a self-closing valve, including a valve cover 1, a connecting cover 9, a connecting rod 2, a safety helmet 3, a lifting knob 4, and a diaphragm 5. A first sliding hole 101 penetrates through the top of the valve cover 1. The connecting cover 9 is sleeved on the valve cover 1, and the connecting cover 9 can rotate and move relative to the valve cover 1. A docking ring 901 is integrally formed at the bottom of the connecting cover 9, and a connecting sleeve 902 is integrally formed at the top of the connecting cover 9.

[0023] A first connecting ring 102 is integrally formed on the outer wall of the bottom of the valve cover 1. The outer wall of the first connecting ring 102 is in threaded cooperation with the inner wall of the docking ring 901, so that the valve cover 1 is positioned in the valve cover 1. The inner wall of the connecting sleeve 902 and the top surface of the valve cover 1 cooperate to form a connecting groove. A columnar operating part 401 is formed at the bottom of the lifting knob 4. The operating part 401 is inserted into the connecting groove, and the connecting groove is in interference fit or threaded fit with the operating part 401, so that the lifting knob 4 is detachably connected to the connecting sleeve 902. A second sliding hole 402 penetrates through the operating part 401. The first sliding hole 101 is adapted to and communicated with the second sliding hole 402. The connecting rod 2 is slidably connected in the first sliding hole 101 and the second sliding hole 402. One end of the connecting rod 2 extends into the valve cover 1, and the other end of the connecting rod 2 extends out of the valve cover 1.

[0024] The end of the connecting rod 2 extending out of the valve cover 1 is fixedly connected to the safety helmet 3. A slot 406 for inserting the safety helmet 3 is provided at the top of the lifting knob 4, so that the safety helmet 3 is telescopically arranged on the lifting knob 4. A limit snap spring 201 is arranged at the position of the outer wall of the connecting rod 2 relative to the bottom surface of the safety helmet 3. The outer diameter of the limit snap spring 201 is larger than the inner diameter of the second sliding hole 402. When the safety helmet 3 retracts into the slot 406, the limit snap spring 201 separates the safety helmet 3 from the lifting knob 4, so that a clearance fit is formed between the safety helmet 3 and the inner wall of the slot 406, reducing the contact area between the two.

[0025] The end of the connecting rod 2 extending into the valve cover 1 has a connecting unit. The connecting unit includes a connecting snap spring 10, a sealing ring 11, an annular pressing piece 12, and a first magnet 13 arranged in sequence from top to bottom. The diaphragm 5 is located between the annular pressing piece 12 and the first magnet 13. The connecting snap spring 10 is arranged at the position of the outer wall of the connecting rod 2 relative to the top surface of the sealing ring 11. The connecting snap spring 10 abuts against the top surface of the sealing ring 11 to limit the sealing ring 11. The bottom surface of the sealing ring 11 abuts against the top surface of the annular pressing piece 12. The first magnet 13 is fixedly connected to the end surface of the connecting rod 2 by bolts, so that the first magnet 13 and the opposite side of the annular pressing piece 12 clamp the diaphragm 5, and the end of the connecting rod 2 extending into the valve cover 1 is fixedly connected to the diaphragm 5. The periphery of the diaphragm 5 cooperates with the bottom surface of the valve cover 1. Preferably, the outer diameter of the connecting snap spring 10 is larger than the inner diameter of the second sliding hole 402. The connecting snap spring 10 is used to limit the upward sliding stroke of the connecting rod 2 relative to the valve cover 1, and a stepped portion is formed between the connecting snap spring 10 and the top surface of the sealing ring 11. A stepped cavity 103 adapted to the stepped portion is provided on the inner wall of the top of the valve cover 1. When the connecting rod 2 slides upward relative to the valve cover 1 to the position where the stepped portion is inserted into the stepped cavity 103, the sealing ring 11 abuts and fits in the stepped cavity 103 to seal the first sliding hole 101.

[0026] The operating part 401 is detachably connected with a plurality of adjusting units. The plurality of adjusting units are uniformly arranged in a circular array centered on the second sliding hole 402. Preferably, the number of adjusting units can be two or three. The adjusting unit includes an abutting member 6, an elastic member 7, and an adjusting member 8. The operating part 401 is penetrated with a plurality of moving holes 403. The plurality of moving holes 403 are uniformly arranged in a circular array centered on the second sliding hole 402. Each moving hole 403 corresponds to each adjusting unit respectively. The moving hole 403 is for the abutting member 6 to slide and connect, and the moving hole 403 communicates with the second sliding hole 402. Two positioning grooves 405 extending along its axial direction are symmetrically provided on the inner wall of the moving hole 403. The abutting member 6 is provided with a positioning portion 603 slidably connected in the positioning groove 405, which is used to limit the sliding stroke of the abutting member 6 in the moving hole 403 and prevent the abutting member 6 from falling off the moving hole 403 and falling into the second sliding hole 402.

[0027] The outer wall of the operation part 401 is provided with a mounting hole 404 that is coaxially aligned and communicated with the moving hole 403. The adjusting member 8 includes a head 81 and a rod portion 82. The outer wall of the head 81 is in threaded cooperation with the inner wall of the mounting hole 404. An operation groove 801 is formed on the side wall of the head 81 away from the rod portion 82, and the operation groove 801 can be any one of a flat groove, a cross groove, an internal hexagonal groove, etc. The rod portion 82 is in plug-in cooperation with the moving hole 403. The elastic member 7 is arranged between the adjusting member 8 and the abutting member 6. The elastic member 7 is a spring structure. Coaxially aligned first centering portions 802 and second centering portions 602 are respectively arranged on the opposite sides of the rod portion 82 and the abutting member 6. The two sides of the elastic member 7 are respectively sleeved on the first centering portion 802 and the second centering portion 602 to guide the telescopic direction of the elastic member 7.

[0028] A wear-resistant layer 601 is arranged on the side wall of the abutting member 6 close to the connecting rod 2. The wear-resistant layer 601 is matched with the outer wall of the connecting rod 2. Preferably, the wear-resistant layer 601 can be electroplated chromium.

[0029] The user can separate the lifting knob 4 from the connecting sleeve 902. By the threaded connection between the adjusting member 8 and the mounting hole 404, the adjusting member 8 is screwed in or out to more precisely change the compression amount of the elastic member 7, adjust the magnitude of the pre-tightening force of the elasticity, and further change the pressing force of the wear-resistant layer 601 of the abutting member 6 on the outer wall of the connecting rod 2. The abutting member 6 forms interference in the radial direction of the connecting rod 2 to ensure that the up-and-down sliding of the connecting rod 2 is smoother, reduce unnecessary shaking or sliding, and realize the compensation adjustment of the critical pressure value when the air pressure of the self-closing valve exceeds the pressure. It is not necessary to disassemble the entire self-closing valve, and the adjustment operation is relatively convenient. When the air pressure of the self-closing valve reaches the critical pressure value of overpressure, the connecting rod 2 slides upward to a predetermined position, ensuring that the self-closing valve realizes the function of automatic closing when overpressurized and guaranteeing the use effect of the self-closing valve.

[0030] Embodiment 2:

[0031] Reference Figure 5 A self-closing valve includes a valve body shell 14, the lifting mechanism as above, an overcurrent valve 15, and a ball valve switch 16. An air inlet pipe 1401 is formed at one end of the valve body shell 14, and the air inlet pipe 1401 is connected to the overcurrent valve 15. An air outlet pipe 1402 is formed at the other end of the valve body shell 14, and the air outlet pipe 1402 is connected to the ball valve switch 16. The overcurrent valve 15 and the ball valve switch 16 are prior arts and will not be elaborated here in detail.

[0032] An outer wall at the top of the valve body housing 14 is integrally formed with a second connecting ring 1403. The outer wall of the second connecting ring 1403 is in threaded fit with the inner wall of the docking ring 901, so as to complete the snap connection between the valve body housing 14 and the valve cover 1. The periphery of the diaphragm 5 forms a clamping seal when the valve cover 1 and the valve body housing 14 are fixed. An air passage 1404 communicating with the intake pipe 1401 is formed in the inner cavity of the valve body housing 14. The top of the air passage 1404 is provided with a top opening communicating with the inner cavity of the valve body housing 14, and a guide pipe 17 is arranged above the air passage 1404. A plurality of air holes 1701 are formed through the guide pipe 17 corresponding to the position of the top opening. A pressing plate member 18 is slidably connected in the guide pipe 17. Preferably, a second magnet 1801 is embedded in the top surface of the pressing plate member 18. A limiting structure 19 is arranged on the inner wall of the valve body housing 14 above the guide pipe 17. The limiting structure 19 has a through hole 20 for the first magnet 13 to pass through. The first magnet 13 on the connecting rod 2 passes through the through hole 20 and is inserted into the guide pipe 17, and the diameter length of the first magnet 13 is smaller than the inner diameter of the guide pipe 17. The first magnet 13 and the second magnet 1801 are corresponding in position, and the magnetic force between the first magnet 13 and the second magnet 1801 is an attractive force.

[0033] In the initial state, the connecting rod 2 moves downward under the elastic action of the diaphragm 5 to overcome the friction force of each abutting member 6, so that the pressing plate member 18 abuts against the top opening of the air passage 1404 under the guidance of the guide pipe 17 to form a seal. The bottom of the pressing plate member 18 is inserted into the top opening to close the air passage 1404, realizing the self-closed state of the self-closing valve.

[0034] The user can separate the lifting button 4 from the connecting sleeve 902. The lifting button 4 drives the safety helmet 3 to move upward, causing the connecting rod 2 to move upward. The connecting rod 2 drives the connecting unit to move upward. The first magnet 13 and the second magnet 1801 attract each other. The pressing plate member 18 slides upward with the connecting rod 2, so that the sealing between the pressing plate member 18 and the top opening of the air passing channel 1404 is released. The air passing channel 1404 is communicated with the inner cavity of the valve body shell 14 through each air passing hole 1701. The gas input by the air inlet pipe 1401 sequentially passes through the air passing channel 1404, each air passing hole 1701, the inner cavity of the valve body shell 14, and the air outlet pipe 1402, realizing the conduction of the self-closing valve. The air pressure in the valve body shell 14 drives the diaphragm 5 to bulge upward to maintain the ejected position of the connecting rod 2. The user can move the operating part 401 downward relative to the connecting rod 2 and insert it into the slot 406 through the sliding fit of the second sliding hole 402 and the connecting rod 2. When the self-closing valve is underpressure, the diaphragm 5 restores deformation to drive the connecting rod 2 to move downward, so that the self-closing valve switches to the self-closing state. When the self-closing valve is overpressure, the diaphragm 5 continues to bulge upward to drive the connecting rod 2 to move upward to a predetermined position against the magnetic attraction between the first magnet 13 and the second magnet 1801 and the frictional force of each abutting member 6. At this time, the first magnet 13 disengages from the through hole 20 of the limiting structure 19. The limiting structure 19 prevents the pressing plate member 18 from moving upward further, so that the first magnet 13 is separated from the second magnet 1801. The pressing plate member 18 moves downward under its own weight against the air pressure in the air passing channel 1404. When the pressing plate member 18 moves downward in place, the bottom of the pressing plate member 18 is inserted into the top opening to close the air passing channel 1404, so that the self-closing valve switches to the self-closing state. Preferably, a spring member 21 can be arranged between the limiting structure 19 and the pressing plate member 18, so that the pressing plate member 18 has a tendency to move downward, and the first magnet 13 can pass through the hollow area of the spring member 21. The spring member 21 is made of copper alloy material to prevent the spring member 21 from being adsorbed by the first magnet 13 or the second magnet 1801.

[0035] Of course, the above are only typical examples of the present invention. In addition, the present invention can also have many other specific implementation manners. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention.

Claims

1. A lifting mechanism for a self-closing valve, characterized by: The valve cover (1) comprises a valve cover (1), a connecting rod (2), a safety cap (3), a lifting button (4), and a diaphragm sheet (5). The top of the valve cover (1) is penetrated by a first sliding hole (101) for the connecting rod (2) to be slidably connected. The end of the connecting rod (2) extending out of the valve cover (1) is fixedly connected to the safety cap (3). The safety cap (3) is telescopically arranged on the lifting button (4). The top of the valve cover (1) is provided with a connecting sleeve (902). The lifting button (4) is detachably connected to the connecting sleeve (902). The end of the connecting rod (2) extending into the valve cover (1) is fixedly connected to the diaphragm sheet (5). The periphery of the diaphragm sheet (5) cooperates with the bottom surface of the valve cover (1). The bottom of the lifting button (4) is formed with a columnar operating portion (401). The operating portion (401) is penetrated by a second sliding hole (101) adapted to and connected with the first sliding hole (101). 402), the connecting rod (2) is slidably connected in the second sliding hole (402), the operating part (401) is provided with at least one adjustment unit, the adjustment unit includes a contact piece (6), an elastic piece (7), and an adjustment piece (8), the operating part (401) is penetrated by a movable hole (403) for the contact piece (6) to be slidably connected, the movable hole (403) is communicated with the second sliding hole (402), the side wall of the contact piece (6) close to the connecting rod (2) is provided with a wear-resistant layer (601), the wear-resistant layer (601) is in contact with the outer wall of the connecting rod (2), the outer wall of the operating part (401) is provided with a mounting hole (404) coaxially aligned with and communicated with the movable hole (403), the adjustment piece (8) is threadedly connected in the mounting hole (404), and the elastic piece (7) is arranged between the adjustment piece (8) and the contact piece (6).

2. The lifting mechanism of a self-closing valve according to claim 1 is characterized in that: There are a number of adjustment units, and the adjustment units are evenly arranged in a ring array.

3. A lifting mechanism for a self-closing valve according to claim 1 or 2, characterized in that: The adjusting member (8) comprises a head (81) and a rod (82); the outer wall of the head (81) is threadedly matched with the inner wall of the mounting hole (404); an operating groove (801) is provided on the side wall of the head (81) away from the rod (82); and the rod (82) is plug-fitted with the movable hole (403).

4. The lifting mechanism of a self-closing valve according to claim 3 is characterized in that: The elastic member (7) is a spring structure, and the rod portion (82) and the abutment member (6) are respectively provided with a first centering portion (802) and a second centering portion (602) coaxially aligned on opposite sides thereof, and the two sides of the elastic member (7) are respectively sleeved on the first centering portion (802) and the second centering portion (602).

5. The lifting mechanism of a self-closing valve according to claim 1 is characterized in that: The inner wall of the movable hole (403) is provided with at least one positioning groove (405) extending along its axial direction, and the abutment member (6) is provided with a positioning portion (603) slidably connected to the positioning groove (405).

6. The lifting mechanism of a self-closing valve according to claim 1 is characterized in that: The valve body (1) further comprises a connecting cover (9), wherein the connecting cover (9) is sleeved on the valve cover (1), and the connecting cover (9) can rotate relative to the valve cover (1), a docking ring (901) is integrally formed at the bottom of the connecting cover (9), a first connecting ring (102) is provided on the bottom outer wall of the valve cover (1), the outer wall of the first connecting ring (102) is threadedly matched with the inner wall of the docking ring (901), the connecting sleeve (902) is integrally formed at the top of the connecting cover (9), the inner wall of the connecting sleeve (902) is matched with the top surface of the valve cover (1) to form a connecting groove for the operating part (401) to be plugged in, and the connecting groove is interference-fitted or threadedly matched with the operating part (401).

7. The lifting mechanism of a self-closing valve according to claim 1 is characterized in that: A slot (406) for inserting the safety helmet (3) is provided at the top of the lifting button (4), and a limit spring (201) is provided on the outer wall of the connecting rod (2) at a position relative to the bottom surface of the safety helmet (3), and the outer diameter of the limit spring (201) is greater than the inner diameter of the second sliding hole (402).

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