Pneumatic low-temperature stop valve

Abstract

The utility model relates to the technical field of valves, in particular to a pneumatic low-temperature stop valve which comprises a valve body, a valve cover, a valve clack and a valve rod, the valve cover is installed on the top of the valve body, the valve clack is arranged in the valve body, a valve seat matched with the valve clack in a sealing mode is further arranged in the valve body, and the pneumatic low-temperature stop valve further comprises a pneumatic actuator. The pneumatic actuator comprises an air cylinder, a piston and an elastic piece, the piston and the elastic piece are arranged in the air cylinder, one end of the valve rod is connected with the valve clack, the other end of the valve rod sequentially penetrates through the valve cover and the air cylinder to be connected with the piston, and the piston drives the valve rod and the valve clack to axially move away from the valve seat through air source pressure. The stop valve is opened in a pneumatic driving mode, the elastic piece is further installed in the air cylinder to help the valve to be closed, the automatic closing effect is achieved, leakage can be prevented, and the stop valve has the advantages of being simple in structure, convenient to operate, safe and reliable. And the operation safety is also improved.

Description

Technical Field

[0001] The utility model relates to the technical field of valves, in particular to a pneumatic low-temperature stop valve. Background Art

[0002] The stop valve, also known as the gate valve, is a forced sealing valve. Therefore, when the valve is closed, pressure must be applied to the valve disc to force the sealing surface to prevent leakage. The opening and closing part of the stop valve is a plug-shaped valve disc with a flat or sea cone surface on the sealing surface. The valve disc moves in a straight line along the center line of the valve seat.

[0003] In LNG, LN2, LO2 and other cryogenic medium pipelines and devices, a large number of stop valves suitable for various cryogenic conditions must be used. Cryogenic media have potential risk factors such as strong temperature sensitivity, easy expansion, and easy leakage. For the stop valve of the linear switch, the valve seat sealing performance is difficult to guarantee, and the valve stem is also very likely to cause leakage of cryogenic media during the up and down lifting process. Once leakage occurs, the cryogenic medium will produce a heating process after contacting with the normal temperature environment due to the large temperature difference. When the temperature rises, the cryogenic medium will gasify, and the volume will expand hundreds of times during gasification, resulting in a sharp discharge from the leakage point, and even causing the consequences of fire and explosion, which will cause great hidden dangers and potential harm to the on-site operators and devices.

[0004] To this end, users, design institutes and manufacturers have come up with a variety of solutions for improvement, including improving packing, enlarging actuators, using higher-quality sealing materials, etc. Although these applications have alleviated internal leakage, external leakage and operational safety, external leakage and operational safety still exist, and the problem cannot be fundamentally solved. Utility Model Content

[0005] The purpose of the utility model is to overcome the shortcomings and deficiencies of the prior art and to provide a pneumatic low-temperature stop valve. The stop valve of the utility model is opened by a pneumatic drive, and an elastic member is installed in the cylinder to help the valve close, thereby achieving an automatic closing effect, which can not only prevent leakage but also improve the safety of operation.

[0006] The technical scheme adopted by the utility model is as follows: a pneumatic low-temperature stop valve, including a valve body, a valve cover, a valve disc and a valve stem, the valve cover is installed on the top of the valve body, the valve disc is arranged in the valve body, the valve body is also provided with a valve seat that seals with the valve disc, and also includes a pneumatic actuator, the pneumatic actuator includes a cylinder and a piston and an elastic member arranged in the cylinder, one end of the valve stem is connected to the valve disc, and the other end passes through the valve cover and the cylinder in sequence and is connected to the piston, the piston drives the valve stem and the valve disc to move axially away from the valve seat through the pressure of the air source, one end of the elastic member abuts against the inner wall of the cylinder, and the other end abuts against the side of the piston away from the valve cover, the piston drives the valve stem and the valve disc to move axially through the elastic member until the valve disc and the valve seat are sealed and matched.

[0007] It also includes a packing gland and a packing assembly, wherein the packing gland is connected to the valve cover by bolts, and the packing assembly is crimped between the valve cover and the valve stem by the packing gland. The packing assembly includes a boss, a bellows, a packing seat and a packing layer arranged in sequence from bottom to top, the boss is welded to the valve stem, the packing seat is welded to the valve cover, and one end of the bellows is welded to the boss and the other end is welded to the packing seat.

[0008] The inner wall of the valve cover is provided with a first ring platform, the outer wall of the packing seat is provided with a second ring platform extending outward, and the packing seat is abutted and matched with the first ring platform of the valve cover through the second ring platform.

[0009] The valve flap is provided with a first sealing surface, and the valve seat is provided with a second sealing surface that seals with the first sealing surface. The first sealing surface and the second sealing surface are both configured as conical sealing surfaces with an angle of 35° to 45°.

[0010] It also includes a position indicating component, and the piston is also connected to a movable rod. The position indicating component includes a bracket, a connecting shaft and an opening indicator. The bracket is arranged between the valve cover and the cylinder, one end of the connecting shaft is connected to the valve stem through a tightening nut, and the other end is connected to the movable rod through a positioning pin, the opening indicator is arranged on the side wall of the bracket, and a pointer corresponding to the opening indicator is provided on one side of the connecting shaft.

[0011] A scraper-type sealing ring is also provided between the movable rod and the cylinder. The scraper-type sealing ring includes a non-metallic elastic ring and two metal elastic elements, both of which are arranged on the side of the non-metallic elastic ring away from the piston. There is a gap between the two metal elastic elements, and the two metal elastic elements are respectively pressed against the movable rod and the cylinder. A scraper-shaped groove is provided on the side of the non-metallic elastic ring that is in contact with the movable rod.

[0012] The outer wall of the valve cover is provided with a drip plate, and the valve cover is connected to the valve body through a flange, and the diameter of the drip plate is greater than the diameter of the flange.

[0013] The valve cover is also provided with guide ribs, and the valve stem outer sleeve is provided with an anti-rotation block matched with the guide ribs.

[0014] The beneficial effects of the utility model are as follows: the stop valve of the utility model is opened by a pneumatic drive, and an elastic part is installed in the cylinder. The elastic force of the elastic part pushes the piston downward, thereby driving the valve stem and the valve disc to move until the valve is closed, thereby achieving an automatic closing effect. When encountering a gas source or power failure, the valve can also be closed to prevent leakage. If the valve needs to be closed manually, the gas source can be turned off to stop the gas supply, which solves the problems of leakage and operational safety, and is more suitable for low-temperature medium pipelines and devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the utility model.

[0016] Figure 1 This is a structural schematic diagram of a pneumatic low-temperature stop valve of the utility model;

[0017] Figure 2 for Figure 1 A local enlarged schematic diagram of the middle A;

[0018] Figure 3 for Figure 1 A partial enlarged schematic diagram of point B in the middle;

[0019] Figure 4 for Figure 1 A partial enlarged schematic diagram of point C in the middle;

[0020] Figure 5 for Figure 1 A partial enlarged schematic diagram of point D in the middle;

[0021] In the figure, 1-valve body, 2-valve cover, 3-valve disc, 4-valve stem, 5-valve seat, 6-cylinder, 7-piston, 8-elastic part, 9-packing gland, 10-boss, 11-bellows, 12-packing seat, 13-packing layer, 14-first ring platform, 15-second ring platform, 16-first sealing surface, 17-second sealing surface, 18-movable rod, 19-bracket, 20-connecting shaft, 21-opening indicator plate, 22-tightening nut, 23-locating pin, 24-pointer, 25-non-metallic elastic ring, 26-metal elastic element, 27-scraper-shaped groove, 28-drip plate, 29-flange, 30-guide rib, 31-anti-rotation block, 32-conical sealing surface. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the utility model clearer, the utility model will be further described in detail below with reference to the accompanying drawings.

[0023] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0024] The directions and positions mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inside", "outside", "top", "bottom", "side", etc., are only for reference to the directions or positions of the drawings. Therefore, the directions and positions used are used to explain and understand the present invention, but not to limit the scope of protection of the present invention.

[0025] like Figures 1 to 5 The figure shows an embodiment of the utility model, a pneumatic low-temperature stop valve, comprising a valve body 1, a valve cover 2, a valve disc 3 and a valve stem 4, the valve cover 2 is installed on the top of the valve body 1, the valve disc 3 is arranged in the valve body 1, and a valve seat 5 which is sealed with the valve disc 3 is also arranged in the valve body 1, and a pneumatic actuator is also included, the pneumatic actuator comprises a cylinder 6 and a piston 7 and an elastic member 8 which are arranged in the cylinder 6, one end of the valve stem 4 is connected with the valve disc 3, and the other end passes through the valve cover 2 and the cylinder 6 in sequence and is connected with the piston 7, the piston 7 drives the valve stem 4 and the valve disc 3 to move axially away from the valve seat 5 through the pressure of the air source, one end of the elastic member 8 abuts against the inner wall of the cylinder 6, and the other end abuts against the side of the piston 7 away from the valve cover 2, and the piston 7 drives the valve stem 4 and the valve disc 3 to move axially through the elastic member 8 until the valve disc 3 and the valve seat 5 are sealed.

[0026] The beneficial effects of such a setting are as follows: the stop valve of the utility model is opened by a pneumatic drive, and an elastic part is installed in the cylinder. The elastic force of the elastic part pushes the piston downward, thereby driving the valve stem and the valve disc to move until the valve is closed, thereby achieving an automatic closing effect. When encountering an air source or power failure, the valve can also be closed to prevent leakage. If the valve needs to be closed manually, the air source can be turned off to stop the air supply, which solves the problems of leakage and operational safety, and is more suitable for low-temperature medium pipelines and devices.

[0027] Further configuration includes a packing gland 9 and a packing assembly, wherein the packing gland 9 is connected to the valve cover 2 by bolts, and the packing assembly is crimped between the valve cover 2 and the valve stem 4 by the packing gland 9, and the packing assembly includes a boss 10, a bellows 11, a packing seat 12 and a packing layer 13 arranged in sequence from bottom to top, the boss 10 is welded to the valve stem 4, the packing seat 12 is welded to the valve cover 2, and one end of the bellows 11 is welded to the boss 10 and the other end is welded to the packing seat 12.

[0028] The beneficial effects of this arrangement are as follows: the bellows is a telescopic structure, and the bellows, packing seat and boss are all sealed and welded, which completely blocks the medium leakage channel between the valve cover and the valve stem. The valve stem will not leak at all during movement, and the packing layer forms a double combined seal, which further improves the sealing performance and ensures the absolute safety of the valve stem seal, meeting the requirements of low-temperature medium pipelines.

[0029] It is further provided that the inner wall of the valve cover 2 is provided with a first annular platform 14 , the outer wall of the packing seat 12 is provided with a second annular platform 15 extending outwardly, and the packing seat 12 is abutted and matched with the first annular platform 14 of the valve cover 2 via the second annular platform 15 .

[0030] The beneficial effect of such arrangement is as follows: due to the structural restrictions of the first ring platform and the second ring platform, the packing seat can only be installed from the bottom to the top of the valve cover, which not only improves the structural strength but also increases the sealing performance.

[0031] It is further provided that the valve disc 3 is provided with a first sealing surface 16, and the valve seat 5 is provided with a second sealing surface 17 which seals with the first sealing surface 16, and the first sealing surface 16 and the second sealing surface 17 are both set as conical sealing surfaces 32 with an angle of 35° to 45°.

[0032] The beneficial effects of such a setting are as follows: the valve disc and the valve seat adopt a conical sealing surface, and the conical surface adopts an angle range of 35° to 45°, instead of the conventional 60°, so that the sealing surface has a better wedging force under low-temperature media, and the first sealing surface of the valve disc and the second sealing surface of the valve seat are better matched, thereby having better sealing performance.

[0033] Further, a position indicating assembly is included, and the piston 7 is also connected to a movable rod 18. The position indicating assembly includes a bracket 19, a connecting shaft 20 and an opening indicator 21. The bracket 19 is arranged between the valve cover 2 and the cylinder 6. One end of the connecting shaft 20 is connected to the valve stem 4 through a tightening nut 22, and the other end is connected to the movable rod 18 through a positioning pin 23. The opening indicator 21 is arranged on the side wall of the bracket 19, and a pointer 24 corresponding to the opening indicator 21 is provided on one side of the connecting shaft 20.

[0034] The beneficial effects of such a setting are as follows: the connecting shaft connects the valve stem and the movable rod together, the connecting shaft moves synchronously with the valve stem and the movable rod, the pointer on the connecting shaft points to the opening indicator plate, the opening indicator plate is marked with scales, and the opening and closing actions of the valve can be fully reflected by the pointer and the opening indicator plate.

[0035] It is further configured that a scraper-type sealing ring is provided between the movable rod 18 and the cylinder 6, and the scraper-type sealing ring includes a non-metallic elastic ring 25 and two metal elastic elements 26, both of which are arranged on the side of the non-metallic elastic ring 25 away from the piston 7. There is a gap between the two metal elastic elements 26, and the two metal elastic elements 26 are respectively pressed against the movable rod 18 and the cylinder 6. A scraper-shaped groove 27 is provided on the side of the non-metallic elastic ring 25 that is in contact with the movable rod 18.

[0036] The beneficial effects of this arrangement are as follows: when the movable rod moves up and down, the scraper-type sealing ring can automatically clean the surface of the movable rod, preventing impurities and dust from invading the interior of the cylinder, thereby protecting the high purity of the cylinder chamber. The two metal elastic elements provide support so that the scraper-shaped groove is close to the surface of the movable rod, ensuring a good cleaning effect.

[0037] It is further provided that a drip plate 28 is provided on the outer wall of the valve cover 2 , and the valve cover 2 is connected to the valve body 1 via a flange 29 , and the diameter of the drip plate 28 is greater than the diameter of the flange 29 .

[0038] The beneficial effects of such arrangement are as follows: preventing the condensate of the low-temperature medium from rusting the flange and the bolts and nuts installed on the flange, and further accelerating the isolation of the low-temperature medium, thereby protecting the packing from condensation and ice formation.

[0039] Furthermore, the valve cover 2 is provided with a guide rib 30 , and the valve stem 4 is outer-coated with an anti-rotation block 31 matched with the guide rib 30 .

[0040] The beneficial effects of such a configuration are as follows: through the cooperation of the guide rib and the anti-rotation block, the anti-rotation block moves up and down along the guide rib, which can prevent the valve stem from rotating to protect the bellows and prevent the bellows from torsion damage.

[0041] In summary, the following is the principle of the utility model. When the valve is normally opened, the air source pressure drives the piston to move upward, and the piston drives the movable rod and the valve stem to drive the valve disc to move and open the valve. If the valve needs to be closed, the air source is closed to stop the air supply. If there is a gas source or power failure, the spring at the upper end of the piston drives the piston downward, and the piston drives the movable rod and the valve stem to drive the valve disc to move and close the valve. Because the valve disc and the valve seat sealing surface have better wedging force when the valve is closed, better sealing performance can be obtained, and the valve stem has a double sealing structure protection of bellows and packing, which prevents leakage of the medium. This ensures the long-term reliable and safe application of pneumatic stop valves under low-temperature media.

[0042] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present invention.

Claims

1. A pneumatic low-temperature stop valve, comprising a valve body (1), a valve cover (2), a valve disc (3) and a valve stem (4), wherein the valve cover (2) is mounted on the top of the valve body (1), the valve disc (3) is arranged in the valve body (1), and a valve seat (5) is further arranged in the valve body (1) and is in sealing cooperation with the valve disc (3), characterized in that: The invention also comprises a pneumatic actuator, which comprises a cylinder (6), a piston (7) and an elastic member (8) arranged in the cylinder (6); one end of the valve stem (4) is connected to the valve disc (3), and the other end passes through the valve cover (2) and the cylinder (6) in sequence and is connected to the piston (7); the piston (7) drives the valve stem (4) and the valve disc (3) to move axially away from the valve seat (5) through the pressure of the air source; one end of the elastic member (8) abuts against the inner wall of the cylinder (6), and the other end abuts against a side of the piston (7) away from the valve cover (2); the piston (7) drives the valve stem (4) and the valve disc (3) to move axially through the elastic member (8) until the valve disc (3) and the valve seat (5) are sealed and matched.

2. A pneumatic cryogenic stop valve according to claim 1, characterized in that: It also includes a packing gland (9) and a packing assembly, wherein the packing gland (9) is connected to the valve cover (2) via bolts, and the packing assembly is crimped between the valve cover (2) and the valve stem (4) via the packing gland (9). The packing assembly includes a boss (10), a bellows (11), a packing seat (12), and a packing layer (13) which are arranged in sequence from bottom to top, the boss (10) is welded to the valve stem (4), the packing seat (12) is welded to the valve cover (2), and one end of the bellows (11) is welded to the boss (10) and the other end is welded to the packing seat (12).

3. A pneumatic low-temperature stop valve according to claim 2, characterized in that: The inner wall of the valve cover (2) is provided with a first annular platform (14), the outer wall of the packing seat (12) is provided with a second annular platform (15) extending outwards, and the packing seat (12) is abutted and matched with the first annular platform (14) of the valve cover (2) via the second annular platform (15).

4. A pneumatic low-temperature stop valve according to claim 1, characterized in that: The valve flap (3) is provided with a first sealing surface (16), and the valve seat (5) is provided with a second sealing surface (17) which is in sealing cooperation with the first sealing surface (16), and the first sealing surface (16) and the second sealing surface (17) are both configured as conical sealing surfaces (32) with an angle of 35° to 45°.

5. The pneumatic cryogenic stop valve according to claim 1, characterized in that: The valve also includes a position indicating assembly, wherein the piston (7) is further connected to a movable rod (18), and the position indicating assembly includes a bracket (19), a connecting shaft (20), and an opening indicator plate (21). The bracket (19) is arranged between the valve cover (2) and the cylinder (6), one end of the connecting shaft (20) is connected to the valve stem (4) via a tightening nut (22), and the other end is connected to the movable rod (18) via a positioning pin (23), the opening indicator plate (21) is arranged on the side wall of the bracket (19), and a pointer (24) corresponding to the opening indicator plate (21) is provided on one side of the connecting shaft (20).

6. A pneumatic low-temperature stop valve according to claim 5, characterized in that: A scraper-type sealing ring is also provided between the movable rod (18) and the cylinder (6), the scraper-type sealing ring comprising a non-metallic elastic ring (25) and two metal elastic elements (26) both provided on a side of the non-metallic elastic ring (25) away from the piston (7), a gap being provided between the two metal elastic elements (26), and the two metal elastic elements (26) respectively abut against the movable rod (18) and the cylinder (6), and a scraper-shaped groove (27) is provided on a side of the non-metallic elastic ring (25) that is in contact with the movable rod (18).

7. The pneumatic cryogenic stop valve according to claim 1, characterized in that: The outer wall of the valve cover (2) is provided with a drip plate (28); the valve cover (2) is connected to the valve body (1) via a flange (29); and the diameter of the drip plate (28) is greater than the diameter of the flange (29).

8. The pneumatic cryogenic stop valve according to claim 1, characterized in that: The valve cover (2) is also provided with a guide rib (30), and the valve stem (4) is covered with an anti-rotation block (31) that matches the guide rib (30).

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