A sealing structure for sealing valve stem and valve body

Abstract

A sealing structure for sealing a valve stem and a valve body, comprising: a packing containment body (1) sleeved on the valve stem; a first packing group (2) arranged between the valve stem and the packing containment body; a transition sleeve (3) sleeved on the valve stem and located upstream of the first packing group, gaps being respectively left between the inner peripheral wall of the transition sleeve (3) and the outer peripheral wall of the valve stem and between the outer peripheral wall of the transition sleeve (3) and the inner peripheral wall of the packing containment body (1), the temperature of the medium leaking from the transition sleeve (3) to the first packing group (2) being lower than the use temperature of the first packing group; a sealing component, the sealing component being circumferentially arranged in a sealing space (100) located upstream of the transition sleeve (3) to prevent the medium from entering the gap, or / and the sealing component being arranged in the gap to prevent the medium from entering a low-temperature sealing section. The present application can reduce the risk of medium leakage to the outside under high temperature and high pressure conditions and increase the service life of the packing.

Description

Technical Field

[0001] The invention belongs to the technical field of valve sealing, and in particular relates to a sealing structure for sealing a valve stem and a valve body. Background Art

[0002] The valve is a pipeline accessory used to open and close pipelines, control flow direction, regulate and control the conveying medium. According to its function, valves can be divided into shut-off valves, check valves, regulating valves, etc. The main structure of the shut-off valve includes: valve body, valve cover, valve stem, valve disc (valve core), stuffing culvert, drive device (manual, electric, pneumatic, hydraulic drive, etc.), among which one end of the valve stem extends into the valve body, connected to the valve disc, and directly contacts the internal medium, and the other end is outside the valve body and connected to the drive device to control the opening and closing of the valve disc. There is a gap fit between the valve stem and the valve body. In order to prevent the medium in the valve body from leaking outward along the gap between the valve stem and the valve body, a stuffing culvert is provided between the valve stem and the valve body, and stuffing is filled between the stuffing culvert and the valve stem, and is pressed with a pressure plate and a pressure ring (which can be made into a whole), thereby forming a sealing system, which can ensure that the valve stem moves along its axial direction or rotates freely around its axis without medium leakage.

[0003] When the medium temperature is not high, there are a variety of sealing materials that can be used as fillers in the sealing structure. However, when the medium temperature is high (>500℃), the selection of sealing materials is extremely difficult. Specifically, high-pressure resistant sealing fillers such as graphite fillers and synthetic organic braided fillers cannot withstand such high temperatures, while high-temperature resistant fillers such as glass fiber and mica cannot guarantee a small leakage rate under high pressure. When high temperature is accompanied by high pressure (>1MPa), sealing will be more difficult.

[0004] In order to solve the problem of difficult sealing between valve stem and valve body under high temperature and high pressure, the invention patent with patent number ZL03145406.2, "High temperature and high pressure valve stem active sealing mechanism and gate valve using such sealing mechanism" (authorization announcement number CN1186550C), discloses a sealing mechanism, the valve cover of which is provided with a stuffing box opening to the inner cavity of the valve body, and several layers of stuffing, stuffing pads and compression nuts are arranged in the stuffing box from top to bottom, and the compression nut presses the stuffing and stuffing pad together, so that the stuffing is radially deformed, generating a sealing pressure ratio at room temperature, and the deformation of the stuffing box at high temperature is in the same direction and synchronous with the deformation of the stuffing pad and the compression nut, and the medium pressure under high pressure acts on the lower end face of the stuffing pad through the compression nut, which increases the pressure on the stuffing and improves the sealing effect. This patent achieves good sealing between the valve stem and the valve body under high temperature and high pressure by improving the compression nut, stuffing pad and stuffing box structure. However, the packings as mentioned above usually have the problem of high-temperature burning, and it is difficult to ensure its sealing under high temperature and high pressure, so that the above patent still has the risk of medium leakage; and once leakage occurs, the packing is easily damaged by the medium, resulting in a shorter packing life, which in turn leads to a too short valve maintenance cycle.

[0005] In order to solve the problem of medium leakage, the existing technology often uses a method of draining the leaked medium, but this method not only increases the complexity of the system, but also requires finding a pipeline or container of low-pressure medium nearby, otherwise the drained medium has nowhere to be discharged. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a sealing structure for sealing a valve stem and a valve body in view of the current status of the prior art, so as to reduce the risk of medium leakage to the outside under high temperature and high pressure conditions and increase the service life of the packing.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a sealing structure for sealing a valve stem and a valve body, comprising:

[0008] The stuffing containment body is an axially penetrating cylindrical structure and is sleeved on the valve stem. A sealing space is provided between the inner peripheral wall of the stuffing containment body and the outer peripheral wall of the valve stem.

[0009] A first packing group is arranged in the sealing space along the circumferential direction to form a low-temperature sealing section for sealing the medium, and the first packing group is sealed with the inner circumferential wall of the packing containment body and the outer circumferential wall of the valve stem;

[0010] A compression assembly is provided on the end of the stuffing enclosure and is used to axially compress the components in the sealing space;

[0011] It is characterized by also including:

[0012] A transition sleeve is located in the sealing space and sleeved on the valve stem. Along the medium flow path, the transition sleeve is located upstream of the first packing group to form a cooling section for reducing the medium temperature. The transition sleeve is in contact with the opposite end faces of the first packing group. Gaps are respectively left between the inner circumferential wall of the transition sleeve and the outer circumferential wall of the valve stem, and between the outer circumferential wall of the transition sleeve and the inner circumferential wall of the packing body to ensure that the tightening force is transmitted without affecting the normal movement of the valve stem, and at the same time, the medium is restricted from flowing along it to reduce the medium temperature, so that the medium temperature leaking from the transition sleeve to the first packing group is lower than the use temperature of the first packing group;

[0013] A sealing assembly is circumferentially arranged in a sealing space upstream of the transition sleeve to further prevent the medium from entering the gap, or / and the sealing assembly is arranged in the above-mentioned gap to prevent the medium from entering the low-temperature sealing section.

[0014] Preferably, the above gap is as small as possible while ensuring the normal movement of the valve stem to limit the flow of the medium along the gap. The radial dimension of the gap between the inner circumferential wall of the transition sleeve and the outer circumferential wall of the valve stem is preferably 0.1-0.5% of the outer diameter of the valve stem or the inner diameter of the transition sleeve; the radial dimension of the gap between the outer circumferential wall of the transition sleeve and the inner circumferential wall of the packing containment body is preferably 0.1-0.5% of the outer diameter of the transition sleeve or the inner diameter of the packing containment body. Of course, under the condition that the sealing assembly can effectively block the medium, the size of the above gap can also be outside the above range of 0.1-0.5%.

[0015] In order to reduce the flow velocity of the medium in the gap and further reduce the medium temperature, preferably, the inner circumferential wall and / or the outer circumferential wall of the transition sleeve are provided with a blocking member for blocking the medium from flowing along the gap and further reducing the medium temperature in the gap.

[0016] Furthermore, the blocking member includes blocking teeth arranged on the outer peripheral wall of the transition sleeve, and the blocking teeth have at least three groups and are distributed along the axial direction, and a groove body is formed between two adjacent groups of blocking teeth. The blocking teeth on the outer peripheral wall of the transition sleeve increase the flow resistance of the medium on the one hand, and on the other hand, cause the medium fluid to generate eddy currents, increase the convection heat transfer coefficient and thus accelerate the cooling rate. The blocking member is not limited to a tooth-like structure, but may also be a sheet-like structure, etc., as long as it can block the flow of the medium. In addition to the above-mentioned method, the blocking teeth may also be arranged only on the inner peripheral wall of the transition sleeve, or on the inner and outer peripheral walls of the transition sleeve at the same time, and the specific design is based on the actual working conditions.

[0017] Furthermore, the sealing assembly includes a valve stem piston ring or a second packing group, and a first groove is opened on the inner circumferential wall of the transition sleeve along the circumferential direction. The valve stem piston ring or the second packing group is arranged in the first groove and cooperates with the valve stem and the transition sleeve in a sealing manner. Since there is a seal in the gap between the valve stem and the transition sleeve, most of the medium enters the gap between the transition sleeve and the packing containment body, and the flow rate is reduced by the action of the blocking teeth; in the present application, the gaps between the transition sleeve and the valve stem and the packing containment body may not be sealed, and only a seal is set in the sealing space upstream of the transition sleeve to prevent the medium from flowing into the gap; seals may also be set in the gaps between the transition sleeve and the valve stem and the packing containment body. In this case, a seal may be set in the sealing space upstream of the transition sleeve, or no seal may be set separately; of course, a seal may also be set in only one of the gaps, which is specifically designed according to actual working conditions.

[0018] When the second packing group is used for sealing, preferably, the first groove has at least two circles and is arranged close to the first packing group, and the first grooves are spaced apart along the axial direction on the transition sleeve; being arranged close to the first packing group can reduce the temperature of the second packing group, thereby increasing the service life of the second packing group. When the valve stem piston ring is used for sealing, since the piston ring is basically not affected by temperature, the position of the first groove is not limited.

[0019] Furthermore, a groove matching with the blocking teeth is provided on the inner circumferential wall of the packing containment body at a position corresponding to the transition sleeve. The provision of the groove further reduces the flow velocity of the medium, thereby increasing the retention time of the medium on the transition sleeve and further reducing the temperature of the medium. The groove can be provided around the inner circumferential wall of the packing containment body, or the groove and the blocking teeth can be matched to form a maze structure, etc., to reduce the leakage of the medium.

[0020] To further improve the sealing performance, each group of blocking teeth has a plurality of blocking tooth units spaced apart in the axial direction, a second groove is formed between two adjacent blocking tooth units, and the sealing assembly includes a transition sleeve piston ring, which is set in the second groove and seals with the transition sleeve and the packing containment body. Preferably, there are 3 to 5 groups of blocking teeth, and each group of blocking teeth has 5 to 15 blocking tooth units.

[0021] In the above scheme, in order to reduce the risk of high-temperature medium leaking into the transition sleeve, preferably, the sealing assembly includes a third packing group, and the third packing group is circumferentially arranged in the above-mentioned sealing space and located upstream of the above-mentioned transition sleeve to form a high-temperature sealing section. The transition sleeve and the opposite end faces of the third packing group are abutted against each other, and the third packing group is sealed and matched with the outer circumferential wall of the valve stem and the inner circumferential wall of the packing containment body.

[0022] Further preferably, the third packing group includes a packing 1 that plays a role in resisting medium scouring and a packing 2 that plays a sealing role, the packing 1 is located at both axial ends of the packing 2 and the two are in contact with each other; the maximum operating temperature of the packing 1 and the packing 2 is 750°C; the first packing group includes a packing 4 that plays a role in resisting medium scouring and a packing 5 that plays a sealing role, the packing 4 is located at both axial ends of the packing 5 and the two are in contact with each other; the maximum operating temperature of the packing 4 and the packing 5 is 450-500°C. In this way, the packing with anti-scouring effect is surrounded at both ends of the packing with sealing effect, which can better protect the middle packing from being damaged by scouring, thereby increasing the service life of the packing and ensuring the sealing effect. Each of the above-mentioned packings can adopt existing packings to meet the requirements of sealing and scouring resistance.

[0023] In the above-mentioned solutions, in order to further reduce the temperature of the medium leaking to the first packing group, a heat sink for heat dissipation is also included, and the heat sink is arranged on the packing containment body.

[0024] Furthermore, the heat sink is arranged on the packing body at the position corresponding to the transition sleeve, and the heat sink includes a plurality of heat sinks, each of which is arranged on the outer peripheral wall of the packing body along the circumferential direction, and the heat sinks are spaced apart along the axial direction. The heat sink can extend radially outward, or be twisted into a petal shape to further improve the heat dissipation effect. The heat sink can also adopt a structure such as a heat dissipation fan. The heat sink is preferably 4 to 8 pieces, and each heat sink can be welded to the packing body or connected to the packing body as a whole.

[0025] In the above schemes, the clamping assembly includes a compression ring, a compression plate, a pull rod and a nut. The compression ring is sleeved on the valve stem and inserted into the sealing space at both ends of the stuffing cage body, and abuts against the components in the sealing space; the compression plate is sleeved on the valve stem and connected to the compression ring located on the outer end of the stuffing cage body, one end of the pull rod is hinged on the stuffing cage body, and a hole is opened on the periphery of the pressure plate for the other end of the pull rod to pass through. The other end of the pull rod is connected to the nut after passing through the hole to clamp the pressure plate and the compression ring on the stuffing cage body.

[0026] Compared with the prior art, the advantages of the present invention are: by arranging a transition sleeve upstream of the first packing group, a gap is left between the transition sleeve and the outer circumferential wall of the valve stem and the inner circumferential wall of the packing containment body, so that the setting of the transition sleeve will not affect the normal operation of the valve stem; at the same time, although the existence of the gap allows the leakage medium to flow along it, it also reduces the temperature of the medium passing through the transition sleeve, so that when the leakage medium enters the first packing group, the temperature of the medium is lower than the operating temperature of the first packing group, thereby avoiding damage to the first packing group, thereby increasing the service life of the packing and reducing the probability of the medium leaking to the outside; by arranging a sealing component, the upstream medium can be prevented from entering the transition sleeve or entering the first packing group along the transition sleeve, thereby ensuring the sealing performance under high temperature and high pressure. Therefore, the sealing structure of the present invention is suitable for high temperature and high pressure working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a partial structural diagram of Embodiment 1 of the present invention;

[0028] Figure 2 for Figure 1 A partial enlarged view of

[0029] Figure 3 for Figure 2 Enlarged view of part A in the middle;

[0030] Figure 4 It is a partial structural diagram of the second embodiment of the present invention;

[0031] Figure 5 for Figure 4 Enlarged view of part B in the middle. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to the accompanying drawings.

[0033] Embodiment 1:

[0034] like Figures 1 to 3 As shown, a preferred embodiment 1 of a sealing structure for sealing a valve stem and a valve body of the present invention is shown, wherein the sealing structure includes a stuffing containment body 1, a first stuffing group 2, a transition sleeve 3, a second stuffing group 4, a third stuffing group 5, and a clamping assembly 6.

[0035] One end of the stuffing containment body 1 is fixed on the valve body. The stuffing containment body 1 is an axially through cylindrical structure, which is sleeved on the valve stem 10 . A sealing space 100 is defined between the inner circumferential wall of the stuffing containment body 1 and the outer circumferential wall of the valve stem 10 .

[0036] The first packing group 2 is arranged in the sealing space 100 along the circumferential direction to form a low-temperature sealing section for sealing the low-temperature medium. The first packing group 2 is sealed with the inner peripheral wall of the packing body 1 and the outer peripheral wall of the valve stem 10. In this embodiment, the first packing group 2 includes a packing 4 21 that plays a role in resisting the erosion of the medium and a packing 5 22 that plays a sealing role. The packing 5 22 has 4 to 8 circles and is arranged along the axial direction. Each circle of the packing 5 22 is in contact with each other. The packing 4 21 has two circles and is respectively located at the two axial ends after the multiple circles of the packing 5 22 are arranged and the two are in contact with each other. The maximum use temperature of the packing 4 21 and the packing 5 22 is 450 to 500°C, wherein the packing 4 21 is woven from a high-sealing material with metal wire (such as graphite packing) plus a lubricating material (such as graphite powder) plus a high-strength material (such as high-silicon glass fiber); the packing 5 22 is pressed from a high-sealing material (such as graphite).

[0037] The above-mentioned transition sleeve 3 is made of metal or non-metal (engineering ceramic) materials that meet the corresponding use temperature requirements and strength requirements. The transition sleeve 3 is sleeved on the valve stem 10 and is located in the above-mentioned sealing space 100. Along the medium flow path, the transition sleeve 3 is located upstream of the above-mentioned first packing group 2 to form a cooling section for reducing the medium temperature. The length of the cooling section in the axial direction is designed according to specific working conditions to reduce the medium temperature, so that the medium temperature leaked from the transition sleeve 3 to the first packing group 2 is lower than the use temperature of the first packing group 2; the transition sleeve 3 is abutted against the opposite end faces of the first packing group 2, and the inner circumferential wall of the transition sleeve 3 is close to the valve stem 10. There are gaps between the outer circumferential walls of the transition sleeve 3 and between the outer circumferential wall of the transition sleeve 3 and the inner circumferential wall of the stuffing hopper 1, and the outer circumferential wall of the transition sleeve 3 is provided with blocking teeth 31 for blocking the medium from flowing along the gap and reducing the temperature of the medium in the gap. There are three groups of blocking teeth 31 and they are spaced along the axial direction. A groove 32 is formed between two adjacent groups of blocking teeth 31, that is, the groove 32 is located on the outer circumferential wall of the transition sleeve 3; each group of blocking teeth 31 has 5 to 15 blocking tooth units 310 spaced along the axial direction, and each blocking tooth unit 310 has a bevel 311 on the upstream surface of the head of the stuffing hopper body near the inner circumferential wall to reduce the pressure drop. At the same time, two circles of first grooves 33 are opened on the inner circumferential wall of the transition sleeve 3 along the circumferential direction. The first grooves 33 are arranged close to the above-mentioned first stuffing group 2, and each circle of first grooves 33 is spaced along the axial direction. In order to reduce the temperature of the medium flowing through the transition sleeve 3, a heat sink is provided at a position on the packing cover 1 corresponding to the transition sleeve 3. The heat sink includes a plurality of annular heat sinks 7. Each circle of heat sinks 7 is circumferentially arranged on the outer wall of the packing cover 1, and the heat sinks 7 are spaced apart along the axial direction.

[0038] The second packing group 4 is disposed in the first groove 33 and is sealed with the valve stem 10 and the transition sleeve 3. In this embodiment, the second packing group 4 is a packing ring woven from a high temperature resistant and wear resistant material (such as glass fiber).

[0039] The third packing group 5 is circumferentially arranged in the sealing space 100 and is located upstream of the transition sleeve 3 to form a high-temperature sealing section. The transition sleeve 3 and the opposite end faces of the third packing group 5 are in contact with each other, and the third packing group 5 is sealed with the outer circumferential wall of the valve stem 10 and the inner circumferential wall of the packing containment body 1. In this embodiment, the third packing group 5 includes a packing 1 51 that plays a role in resisting medium erosion and a packing 2 52 that plays a sealing role. The packing 2 52 has 3 to 5 circles and is arranged along the axial direction. Each circle of the packing 2 52 is in contact with each other. The packing 1 51 has two circles and is respectively located at the two axial ends after multiple circles of the packing 2 52 are arranged and the two are in contact with each other. The maximum operating temperature of the packing 1 51 and the packing 2 52 is 750°C; wherein, the packing 1 51 is woven from high-temperature resistant fibers (such as ceramic fibers) wrapped with high-temperature resistant wires (such as Ni wires) inside and wear-resistant and high-temperature resistant fibers (such as high-silica glass fibers) wrapped with lubricating materials (such as graphite) outside; the packing 2 52 is a packing ring pressed from high-temperature resistant materials (such as mica).

[0040] The above-mentioned clamping assembly 6 is arranged on the end of the stuffing containment body 1, and is used to axially clamp the components in the sealing space 100. The clamping assembly 6 includes a compression ring 61, a compression plate 62, a pull rod 63 and a nut 64. The compression ring 61 is sleeved on the valve stem 10 and inserted into the sealing space 100 at both ends of the stuffing containment body 1, and abuts against the components in the sealing space 100. In this embodiment, one of the compression rings 61 abuts against the third stuffing group 5, and the other compression ring 61 abuts against the first stuffing group 2 to axially compress the first stuffing group 2, the transition sleeve 3 and the third stuffing group 5; the compression plate 62 is sleeved on the valve stem 10 and abuts against the compression plate 62 on the outer end of the stuffing containment body 1. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. The pressure plate 62 is connected to the packing containment body 1 by a pull rod 63. After the nut 64 is tightened, the pre-tightening force is transmitted along the pressure plate 62, the pressure ring 61, the low-temperature sealing section, the cooling section, and the high-temperature sealing section. After being subjected to axial pressure, the axial length of each packing becomes shorter, the radial outer diameter becomes larger, and the inner diameter becomes smaller, so that it fits tightly against the outer circumferential wall of the valve stem 10 and the inner circumferential wall of the packing containment body 1, blocking the leakage channel and playing a sealing role.

[0041] Under normal circumstances, the low-temperature sealing section plays a role of complete sealing, and the medium basically has no leakage. The filler of the high-temperature sealing section is mainly heated by the heat conduction of the valve body, and its temperature is generally slightly lower than the medium temperature. For the filler of the low-temperature sealing section, the heat conduction distance of the valve body is longer, and the heat sink 7 of the cooling section will allow most of the heat to dissipate into the air, so the temperature of the low-temperature sealing section is lower.

[0042] With the continuous wear during use, the high-temperature sealing section may leak, but due to the existence of the high-temperature sealing section, the leakage will be controlled within a very small range, and the leaked medium must first pass through the cooling section. Because a second packing group 4 is provided between the inner circumferential wall of the transition sleeve 3 and the outer circumferential wall of the valve stem 10 in the cooling section, most of the medium will pass through the gap between the outer circumferential wall of the transition sleeve 3 and the inner circumferential wall of the packing containment body 1, and a plurality of groups of blocking teeth 31 are provided on the outer circumferential wall of the transition sleeve 3. The blocking teeth 31 increase the flow resistance on the one hand, and on the other hand, cause the fluid medium to generate eddy currents, increase the convective heat transfer coefficient, and thus accelerate the cooling speed. There are grooves 32 between each group of blocking teeth 31, and the grooves 32 reduce the flow rate of the leaked medium, increase the retention time, and further reduce the medium temperature. In general, the present application obtains a higher heat transfer coefficient at a lower average flow rate, solving the contradiction between the flow rate and the heat transfer coefficient. The heat of the medium is transferred to the packing containment body 1 by convection, and then transferred to the air by the packing containment body 1 and the heat sink 7 on the outside of the packing containment body 1. Therefore, when a small amount of leaked medium reaches the low-temperature sealing section, its temperature is lower than the operating temperature of the filler on the low-temperature sealing section, and will not cause obvious damage to the filler of the low-temperature sealing section. The filler of the high-temperature sealing section has a strong anti-scouring ability, and a small amount of leakage will not cause damage. At this time, it is only necessary to compress the filler through the clamping assembly 6 without stopping the machine to eliminate the leakage, thereby greatly extending the service life of the sealing structure.

[0043] Embodiment 2:

[0044] like Figure 4 , 5 As shown, it is a preferred embodiment 2 of a sealing structure for sealing a valve stem and a valve body of the present invention. The sealing structure is basically the same as the embodiment 1, except that in this embodiment, the second packing group 4 is not required, and the first groove 33 has four circles and is spaced apart along the axial direction. A valve stem piston ring 8 is sleeved in each first groove 33, and the valve stem piston ring 8 is sealed with the valve stem 10 and the transition sleeve 3. At the same time, in this embodiment, a second groove 34 is formed between two adjacent blocking tooth units 310, and a transition sleeve piston ring 9 is sleeved on the second groove 34, and the transition sleeve piston ring 9 is sealed with the transition sleeve 3 and the packing containment body 1. The arrangement of the valve stem piston ring 8 and the transition sleeve piston ring 9 can ensure that the medium cannot flow through the gap to the first packing group 2, thereby reducing the leakage rate of the medium.

[0045] In this embodiment, both the valve stem piston ring 8 and the transition sleeve piston ring 9 can play a good sealing role. Therefore, in order to simplify the structure, the high-temperature sealing section composed of the third packing group 5 is eliminated, and the sealing is achieved only by the structure of the cooling section plus the low-temperature sealing section. Of course, the high-temperature sealing section can also be set at the same time.

[0046] At the same time, the sealing structure of the present application can also be: a structure with a high-temperature sealing section, a cooling section and a low-temperature sealing section as above, the difference being that the sealing member arranged in the gap is eliminated, and blocking teeth are arranged on the inner and outer peripheral walls of the transition sleeve at the same time.

Claims

1. A sealing structure for sealing a valve stem and a valve body, comprising: The stuffing containment body (1) is an axially through cylindrical structure and is sleeved on the valve stem (10). A sealing space (100) is provided between the inner peripheral wall of the stuffing containment body (1) and the outer peripheral wall of the valve stem (10); A first packing group (2) is arranged in the sealing space (100) along the circumferential direction to form a low-temperature sealing section for sealing the medium, and the first packing group (2) is sealed with the inner circumferential wall of the packing containment body (1) and the outer circumferential wall of the valve stem (10); A pressing assembly (6) is arranged on the end of the stuffing enclosure (1) and is used to axially press the components in the sealing space (100); It is characterized by also including: A transition sleeve (3) is located in the sealed space (100) and is sleeved on the valve stem (10). Along the medium flow path, the transition sleeve (3) is located upstream of the first packing group (2) to form a cooling section for reducing the medium temperature. The transition sleeve (3) and the first packing group (2) are in contact with each other at opposite end faces. Gaps are respectively left between the inner circumferential wall of the transition sleeve (3) and the outer circumferential wall of the valve stem (10) and between the outer circumferential wall of the transition sleeve (3) and the inner circumferential wall of the packing containment body (1). The temperature of the medium leaking from the transition sleeve (3) to the first packing group (2) is lower than the use temperature of the first packing group (2). A sealing assembly, which is circumferentially arranged in a sealing space (100) located upstream of the transition sleeve (3) to prevent a medium from entering the gap, or / and the sealing assembly is arranged in the gap to prevent a medium from entering the low-temperature sealing section; The inner circumferential wall or / and the outer circumferential wall of the transition sleeve (3) are provided with a blocking member for blocking the medium from flowing along the gap to further reduce the temperature of the medium in the gap; The blocking member comprises blocking teeth (31) arranged on the outer peripheral wall of the transition sleeve (3), the blocking teeth (31) having at least three groups and spaced apart along the axial direction, and a groove body (32) is formed between two adjacent groups of blocking teeth (31); The sealing assembly comprises a valve stem piston ring (8) or a second packing group (4); a first groove (33) is circumferentially formed on the inner circumferential wall of the transition sleeve (3); the valve stem piston ring (8) or the second packing group (4) is arranged in the first groove (33) and is sealingly matched with the valve stem (10) and the transition sleeve (3); Each group of blocking teeth (31) comprises a plurality of blocking tooth units (310) spaced apart along the axial direction, a second groove (34) is formed between two adjacent blocking tooth units (310), and the sealing assembly comprises a transition sleeve piston ring (9), the transition sleeve piston ring (9) is sleeved in the second groove (34) and is sealingly matched with the transition sleeve (3) and the stuffing containment body (1).

2. The sealing structure according to claim 1, characterized in that: The sealing assembly includes a third packing group (5), which is circumferentially arranged in the above-mentioned sealing space (100) and located upstream of the above-mentioned transition sleeve (3) to form a high-temperature sealing section. The transition sleeve (3) and the opposite end faces of the third packing group (5) are in abutment with each other, and the third packing group (5) is sealed and matched with the outer peripheral wall of the valve stem (10) and the inner peripheral wall of the packing containment body (1).

3. The sealing structure according to claim 2, characterized in that: The third packing group (5) comprises a packing 1 (51) that functions to resist medium erosion and a packing 2 (52) that functions to seal, wherein the packing 1 (51) is located at both axial ends of the packing 2 (52) and the two are in contact with each other; the first packing group (2) comprises a packing 4 (21) that functions to resist medium erosion and a packing 5 (22) that functions to seal, wherein the packing 4 (21) is located at both axial ends of the packing 5 (22) and the two are in contact with each other.

4. The sealing structure according to any one of claims 1 to 3, characterized in that: It also includes a heat sink for heat dissipation, and the heat sink is arranged on the stuffing containment body (1).

5. The sealing structure according to claim 4, characterized in that: The heat sink is arranged on the packing containment body (1) at a position corresponding to the transition sleeve (3), and the heat sink comprises a plurality of heat sinks (7), each heat sink (7) being arranged on the outer peripheral wall of the packing containment body (1) along the circumferential direction, and the heat sinks (7) are spaced apart along the axial direction.

6. The sealing structure according to any one of claims 1 to 3, characterized in that: The clamping assembly (6) comprises a compression ring (61), a compression plate (62), a pull rod (63) and a nut. The compression ring (61) is sleeved on the valve stem (10) and inserted into the sealing space (100) at both ends of the stuffing containment body (1), and abuts against the components in the sealing space (100); the compression plate (62) is sleeved on the valve stem (10) and connected to the compression ring (61) located on the outer end of the stuffing containment body (1); one end of the pull rod (63) is hinged on the stuffing containment body (1); a hole is provided on the periphery of the compression plate (62) for the other end of the pull rod (63) to pass through; the other end of the pull rod (63) is connected to the nut (64) after passing through the hole, so as to clamp the compression plate (62) and the compression ring (61) on the stuffing containment body (1).

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