Upper seal structure of valve stem

Abstract

The utility model provides a kind of upper seal structure of valve stem, including valve body, the valve stem and sealing assembly being arranged in valve body, the sealing cavity being formed between the valve stem and valve body and sealing assembly is arranged in sealing cavity and is used to form the sealing of valve stem, fixed assembly is arranged on the valve body, so that sealing assembly keeps relative position from moving along axial direction, sealing step is arranged in the valve body, the sealing ring that sealing assembly includes cooperates with sealing step, sealing ring forms sealing contact with sealing step, the hardness of sealing ring is greater than packing and is made of metal material not easy to rust.The utility model has the beneficial effects that by setting sealing step in valve body, and with the hard contact type sealing of metal material sealing ring, the sealing reliability of valve stem in high pressure, high temperature or corrosive fluid environment is significantly improved.

Description

Technical Field

[0001] This utility model relates to a sealing structure, and more particularly to an upper sealing structure for a valve stem. Background Technology

[0002] Gate valves are widely used in applications requiring precise flow control, such as chemical, pharmaceutical, heating systems, and water supply networks. Their working principle involves rotating a handwheel or actuator to drive the valve stem, which in turn moves the valve disc up and down within the valve seat, altering the opening of the fluid passage and thus achieving precise flow control. During operation, the valve stem's movement must slide within the stuffing box to ensure the valve maintains a tight seal when open or closed. In contrast, gate valves are primarily used for fully open or fully closed fluid passages, commonly found in oil and gas pipelines, water treatment plants, and fire protection systems. During operation, the valve stem raises or lowers the gate via a threaded mechanism. When the gate is fully raised, fluid flows freely; when the gate descends to the valve seat, the passage is completely sealed. Both types of valves are simple and durable, but in high-pressure or corrosive media environments, the movement of the valve stem can cause packing wear, affecting long-term sealing performance.

[0003] However, existing gate valves and globe valves suffer from a significant drawback: the lack of an upper sealing structure for the valve stem. During valve operation, the valve stem needs to move frequently, but traditional designs rely on packing seals or O-rings. These seals are prone to failure under high pressure, high temperature, or corrosive fluid conditions, leading to leakage at the valve stem. This not only causes fluid loss, environmental pollution, and equipment corrosion, but may also pose safety hazards, such as fires caused by leaks of flammable media. Although improvements such as double packing designs exist, these solutions cannot completely solve the dynamic sealing problem at the upper end of the valve stem. Long-term use leads to accelerated wear of the seals and high maintenance costs, necessitating a more reliable sealing structure to improve overall performance. Utility Model Content

[0004] To address the shortcomings of existing technologies, this utility model provides a valve stem upper sealing structure that solves the problem of dynamic sealing failure at the upper end of the valve stem.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a valve stem upper sealing structure, comprising a valve body, a valve stem disposed within the valve body, and a sealing assembly, wherein a sealing cavity is formed between the valve stem and the valve body, and the sealing assembly is disposed within the sealing cavity and used to form a seal on the valve stem; a fixing component is provided on the valve body to maintain the relative position of the sealing assembly along the axial direction without movement; a sealing step is provided within the valve body; the sealing assembly includes a sealing ring that cooperates with the sealing step, and the sealing ring and the sealing step cooperate to form a sealing contact; the hardness of the sealing ring is greater than that of the filler and is made of a metal material that is not prone to rust.

[0006] The beneficial effects of this invention are as follows: By setting a sealing step within the valve body and forming a hard-contact seal with a metal sealing ring, the sealing reliability of the valve stem under high pressure, high temperature, or corrosive fluid environments is significantly improved. This structure avoids the problem of easy wear and failure of traditional packing or O-rings, reducing the risk of fluid leakage and thus reducing environmental pollution and equipment corrosion hazards. Simultaneously, the high hardness and corrosion resistance of the sealing ring ensure long-term durability, eliminating the need for frequent maintenance. As a preferred embodiment, the sealing ring adopts an annular stainless steel sleeve structure, embedded in the sealing cavity, making direct hard contact with the valve body sealing step; when the valve stem rises and falls, the metal-to-metal fit can withstand high-pressure impacts, forming a durable sealing barrier. As another preferred embodiment, the sealing ring is designed as a detachable annular assembly, fixed around the valve stem by a threaded connection. During valve operation, the tight fit between the sealing ring and the step effectively isolates the fluid, preventing media leakage, making it particularly suitable for harsh conditions in chemical or pharmaceutical systems.

[0007] Furthermore, the sealing step includes a first contact slope, and the sealing ring is provided with a second contact slope corresponding to the first contact slope. The first contact slope and the second contact slope cooperate to form a sealing contact.

[0008] This technical solution, by setting a first contact bevel and a second contact bevel in combination, can effectively counteract the axial offset or slight displacement that may occur in the valve stem during operation, improving the adaptability and reliability of the seal. The beveled contact structure can disperse stress under high pressure, avoid localized wear of the sealing surface, extend service life, and reduce the risk of leakage due to valve stem misalignment. As a preferred embodiment, the first and second contact bevels are designed as 45-degree conical surfaces. During valve stem movement, the beveled fit allows for automatic adjustment of the contact position when the valve stem tilts slightly or vibrates, maintaining seal integrity. As another preferred embodiment, the second contact bevel of the sealing ring is pressed against the first contact bevel of the valve body by a spring preload mechanism, ensuring that the bevels remain in contact during valve opening and closing, preventing gaps in the fluid passage during dynamic operation, and is particularly suitable for frequent adjustment scenarios in thermal systems.

[0009] Furthermore, the valve body is provided with a first axial contact surface, and the sealing ring further includes a U-shaped opening and a second axial contact surface that contacts and forms a tight fit with the second axial contact surface. One end of the U-shaped opening is connected to the second contact slope, and the other end is connected to the second axial contact surface. The U-shaped opening covers part of the first contact slope.

[0010] This design reduces the direct contact area between the first and second contact slopes through a U-shaped opening, lowering the risk of friction and stress concentration. Simultaneously, it adds a tight-fit seal between the first and second axial contact surfaces, providing additional sealing protection and preventing seal failure under high pressure or corrosive conditions. The U-shaped opening structure optimizes the stress distribution on the sealing surface, preventing deformation of the sealing ring after long-term use and enhancing the overall structural stability. As a preferred approach, the U-shaped opening is designed as a groove to accommodate part of the slope of the valve body's sealing step, reducing contact points. The second axial contact surface is tightly fitted to the first axial contact surface of the valve body via an elastic snap. During valve operation, the elastic element compensates for thermal expansion or vibration, ensuring a consistently tight fit between the axial sealing surfaces. As another preferred approach, the inner wall of the U-shaped opening of the sealing ring is covered with a wear-resistant coating, forming a partial contact with the first contact slope. Simultaneously, the second axial contact surface adopts an annular flange structure, which is pressed against the axial surface of the valve body through an interference fit. Under fluid pressure, the flange automatically enhances the sealing force, making it suitable for high-pressure environments in water supply networks.

[0011] Furthermore, the sealing assembly also includes a packing gland, a packing ring, an upper packing, an oil seal, a lower packing, and a packing gasket arranged sequentially from the valve stem toward the valve plate, with the sealing ring being positioned closest to the valve plate in the sealing assembly.

[0012] By incorporating a packing gland, packing ring, packing, oil seal, and packing pad into the sealing assembly, and placing the sealing ring closest to the valve plate, multiple sealing layers are formed, enhancing the overall sealing effect of the valve stem. As the core of the hard-contact seal, the sealing ring works synergistically with the packing and oil seal to provide backup protection in high-pressure or corrosive media, reducing the risk of single-point seal failure and improving the long-term reliability of the valve. As a preferred method, the sealing ring is integrated below the packing pad, adjacent to the valve plate; when the valve is closed, fluid pressure pushes the sealing ring tightly against the sealing step, while the packing and oil seal, as the primary sealing layer, absorb dynamic friction, ensuring that leakage paths are completely blocked. As another preferred method, the sealing ring is fixed to the packing pad via a groove; when the valve stem moves, the packing ring and packing gland apply axial pressure, compressing the upper and lower packing, lubricating the sliding surface of the oil seal, and simultaneously providing a final sealing barrier through the metal-to-metal contact of the sealing ring, making it particularly suitable for high-cleanliness applications in the pharmaceutical industry.

[0013] Furthermore, the fixing component includes a bracket disposed on the valve body and fasteners for fixing the bracket to the valve body, wherein the inner diameter surface of the bracket contacts the packing gland and forms a tight fit.

[0014] This fixing component, through a tight fit between the bracket and the packing gland, ensures that the sealing assembly remains axially fixed, preventing displacement of the seal due to vibration or pressure fluctuations during valve operation, thus maintaining sealing stability. The fixing force of the bracket is transmitted downwards through the packing gland to the entire sealing assembly, enhancing structural rigidity and reliability and reducing maintenance requirements. As a preferred option, the bracket employs an annular flange structure, bolted to the upper end of the valve body; the bracket's inner diameter has internal threads that mate with the external threads of the packing gland to form a tight fit, ensuring even distribution of fixing force during assembly and preventing the packing gland from loosening. Alternatively, the bracket is designed as a split clamp, locked to the valve body with fasteners; the bracket's inner wall has raised ribs that engage with the grooves of the packing gland. During valve opening and closing, the engagement of the ribs and grooves prevents the packing gland from rotating or sliding axially, making it suitable for the vibration environment of oil and gas pipelines.

[0015] Furthermore, the fasteners are respectively disposed around the four sides of the bracket.

[0016] The fasteners are evenly distributed around the bracket, achieving a balanced and stable fixing force. This prevents tilting or loosening caused by uneven force on the bracket, ensuring that the sealing assembly is evenly pressurized throughout the circumference, improving the uniformity and durability of the seal. This design effectively resists thermal expansion or mechanical stress under high pressure or temperature variations, maintaining a long-term sealing effect. As a preferred method, four bolts are used as the fasteners, installed symmetrically at four positions on the bracket. Even tightening of the bolts ensures a tight fit between the bracket and the valve body, with the tightening force evenly transmitted to the packing gland, preventing the sealing assembly from tilting. Alternatively, quick-locking pins are used as the fasteners, inserted into pre-drilled holes around the bracket. During installation, the pin's locking mechanism automatically locks the bracket, ensuring even distribution of tightening force, suitable for the rapid maintenance needs of fire protection systems. Attached Figure Description

[0017] Figure 1 This is an overall schematic diagram of an embodiment of the present utility model;

[0018] Figure 2 This is a partial cross-sectional view of the sealing assembly in an embodiment of the present invention;

[0019] Figure 3 This is a partial enlarged view of the fixing component in an embodiment of the present invention;

[0020] Figure 4 This is a partial enlarged view of the contact surface between the sealing ring and the valve body in an embodiment of this utility model. Detailed Implementation

[0021] An embodiment of this utility model provides an upper sealing structure for a valve stem, as shown below. Figure 1-4As shown: It includes a valve body 1, a valve stem 2, a sealing assembly 4, and a fixing assembly 5. The valve body 1 is set in the whole structure as a basic support component. The valve stem 2 is set inside the valve body 1 to control the flow of fluid. A sealing cavity 3 is formed between the valve stem 2 and the valve body 1 to accommodate the sealing assembly 4. The sealing assembly 4 is installed in the sealing cavity 3 and is used to seal the valve stem 2 to prevent fluid leakage. The valve body 1 is also provided with a fixing assembly 5 to keep the sealing assembly 4 in a relative position along the axial direction and ensure the stability of the seal. A sealing step 11 is set inside the valve body 1 as the basic structure of the hard seal.

[0022] The sealing assembly 4 includes a sealing ring 41, which cooperates with the sealing step 11 to form a sealing contact. The sealing ring 41 has a higher hardness than the packing and is made of a metal material that is not easy to rust, such as stainless steel, thus forming a more reliable hard contact seal in addition to the packing seal. The sealing step 11 includes a first contact slope 111, and the sealing ring 41 is correspondingly provided with a second contact slope 411. The first contact slope 111 and the second contact slope 411 cooperate to form a sealing contact. This slope contact can offset part of the axial displacement generated when the valve stem 2 is operated. The valve body 1 is provided with a first axial contact surface 112. The sealing ring 41 also includes a U-shaped opening 412 and a second axial contact surface 413 that contacts the first axial contact surface 112 and forms a tight fit. One end of the U-shaped opening 412 is connected to the second contact slope 411, and the other end is connected to the second axial contact surface 413. The U-shaped opening 412 covers part of the first contact slope 111. By setting the U-shaped opening 412, the contact area between the first contact slope 111 and the second contact slope 411 is reduced. In order to prevent the seal from failing easily, a sealing contact is added between the first axial contact surface 112 and the second axial contact surface 413 to provide additional protection.

[0023] The sealing assembly 4 also includes a packing gland 42, a packing ring 43, an upper packing 44, an oil seal 45, a lower packing 46, and a packing pad 47 arranged sequentially from the valve stem 2 toward the valve plate. The packing gland 42, the packing ring 43, the upper packing 44, the oil seal 45, the lower packing 46, and the packing pad 47 are all common sealing elements used to form a multi-stage soft seal. The sealing ring 41 is located closest to the valve plate in the sealing assembly 4. The hard contact seal between the sealing ring 41 and the valve body 1 is reinforced by these existing packing seals and oil seals, thereby improving the overall sealing reliability.

[0024] The fixing component 5 includes a bracket 51 mounted on the valve body 1 and fasteners 52 that fix the bracket 51 to the valve body 1. The inner diameter surface of the bracket 51 contacts the packing gland 42 and forms a tight fit. The axial position of the packing gland 42 is fixed by the bracket 51. Since the packing gland 42 is located at the uppermost end of the sealing component 4, the axial fixing force will be transmitted downward through the packing gland 42 to the entire sealing component 4. The fasteners 52 are arranged around the bracket 51 to provide a uniform fixing force, making the fixing more stable.

[0025] The working principle of this embodiment is as follows: When the valve stem 2 is operated, the sealing assembly 4 remains stable under the axial fixation of the fixing assembly 5. The hard contact seal of the sealing ring 41 offsets the axial offset through the cooperation of the first contact slope 111 and the second contact slope 411. At the same time, the design of the U-shaped opening 412 reduces the concentration of contact stress. The tight fit between the first axial contact surface 112 and the second axial contact surface 413 prevents the seal from failing. The soft sealing layer formed by the packing gland 42, packing ring 43, upper packing 44, oil seal 45, lower packing 46 and packing pad 47 further strengthens the sealing effect, ensuring reliable sealing under high pressure or frequent operation.

[0026] The above embodiments are merely one preferred embodiment of the present utility model. Ordinary changes and substitutions made by those skilled in the art within the scope of the present utility model's technical solution are all included within the protection scope of the present utility model.

Claims

1. A valve stem upper sealing structure, comprising a valve body, a valve stem disposed within the valve body, and a sealing assembly, wherein a sealing cavity is formed between the valve stem and the valve body, and the sealing assembly is disposed within the sealing cavity and serves to form a seal on the valve stem, wherein the valve body is provided with a fixing component that maintains the relative position of the sealing assembly along the axial direction without movement, characterized in that: The valve body is provided with a sealing step, and the sealing assembly includes a sealing ring that cooperates with the sealing step. The sealing ring and the sealing step cooperate to form a sealing contact. The hardness of the sealing ring is greater than that of the packing and it is made of a metal material that is not easy to rust.

2. The upper stem seal arrangement of claim 1, wherein: The sealing step includes a first contact slope, and the sealing ring is provided with a second contact slope corresponding to the first contact slope. The first contact slope and the second contact slope cooperate to form a sealing contact.

3. The upper stem seal arrangement of claim 2, wherein: The valve body is provided with a first axial contact surface, and the sealing ring further includes a U-shaped opening and a second axial contact surface that contacts and forms a tight fit with the second axial contact surface. One end of the U-shaped opening is connected to the second contact slope, and the other end is connected to the second axial contact surface. The U-shaped opening covers part of the first contact slope.

4. The upper stem seal arrangement of claim 1, wherein: The sealing assembly also includes a packing gland, a packing ring, an upper packing, an oil seal, a lower packing, and a packing gasket arranged sequentially from the valve stem toward the valve plate, with the sealing ring being the closest to the valve plate in the sealing assembly.

5. The upper stem seal arrangement of claim 4, wherein: The fixing assembly includes a bracket mounted on the valve body and fasteners for fixing the bracket to the valve body. The inner diameter surface of the bracket contacts the packing gland and forms a tight fit.

6. The upper stem seal arrangement of claim 5, wherein: The fasteners are respectively installed around the four sides of the bracket.

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