Sealing structure of track ball valve

Abstract

A kind of sealing structure of track ball valve, including valve body and the valve clack of being set in valve body and being spherical, the valve seat being contacted with the outer surface of valve clack is arranged in the valve body, the sealing element being cooperated with the outer surface of valve clack is arranged on the valve seat, when the valve clack rotates from closed state to open state, the pressure of the outer surface of valve clack against sealing element gradually increases.The beneficial effects of the utility model are: by gradually increasing the pressure of sealing element to the valve clack in the process of rotation, effectively avoid the risk that sealing element is blown out or cold shrinked out due to medium impact force in high pressure difference opening instant.

Description

Technical Field

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

[0002] Orbital ball valves, as a key fluid control device, are widely used in harsh conditions such as high pressure, high temperature, or corrosiveness in industries like petrochemicals, natural gas transportation, power generation, and pharmaceuticals. Their core function lies in achieving rapid opening and closing or precise adjustment of the flow path through a 90-degree rotation of the ball around its axis. During operation, the helical guide groove at the upper end of the valve stem interacts with the embedded pin, driving the ball to first move slightly backward along the normal direction of the valve seat sealing surface, disengaging from the sealing contact, and then rotating without friction. When closing, the process is reversed; after rotating to its final position, the ball returns to its original position, pressing the seal firmly. This unique "lift-rotation" composite motion mechanism effectively avoids mechanical scraping between the sealing surfaces, significantly improving the lifespan of the sealing surface, making it particularly suitable for pipeline systems requiring frequent opening and closing, zero leakage, and long-term operation.

[0003] However, existing soft-seal ball valves relying on elastic seals have significant drawbacks under extreme high-pressure or cryogenic conditions. In low-pressure environments, elastic seals (such as O-rings or PTFE lips) embedded in the valve seat groove can reliably seal; however, when system pressure surges, if the valve needs to open under a high pressure differential, the immense medium pressure will directly act on the exposed side of the seal as the ball moves backward, creating a tendency to forcefully blow it out of the valve seat groove ("blowout failure"). Especially in emergency opening conditions, the peeling force generated by the pressure differential can cause the seal to tear, detach, or even be displaced by the medium, resulting in the valve completely losing its sealing function. Furthermore, in cryogenic applications (such as LNG), the significant difference in the coefficients of thermal contraction between the metal valve body and non-metallic seals leads to a substantial reduction in the radial clamping force of the groove on the seal during cryogenic contraction, further exacerbating the risk of the seal detaching from the groove ("cold shrinkage ejection failure"), seriously threatening the safety and reliability of the system. Utility Model Content

[0004] To address the shortcomings of existing technologies, this utility model provides a sealing structure for a track ball valve that prevents the seal from dislodging under high pressure or extreme operating conditions.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a sealing structure for a track ball valve, comprising a valve body and a spherical valve disc disposed within the valve body, wherein a valve seat is disposed within the valve body and contacts the outer surface of the valve disc, and a sealing element is disposed on the valve seat and cooperates with the outer surface of the valve disc; when the valve disc rotates from a closed state to an open state, the pressure of the outer surface of the valve disc against the sealing element gradually increases.

[0006] The beneficial effects of this invention are as follows: By gradually increasing the pressure on the seal during valve disc rotation, the risk of the seal being blown out or detached due to media impact or cold contraction during high-pressure differential opening is effectively avoided. When the valve rotates from the closed to the open state, the pressure increases gradually rather than abruptly, reducing the direct effect of peeling force on the seal and thus improving sealing reliability. Especially under extreme conditions of high pressure or ultra-low temperature, the seal can be stably held within the valve seat groove, reducing the probability of failure. As a preferred embodiment, the valve disc can be designed as an eccentric rotating structure, where the rotation axis of the valve disc is offset from the center of the valve body. During rotation, the surface of the valve disc gradually approaches the seal, achieving a linear pressure increase through geometric displacement, ensuring that the media pressure does not concentrate on the side of the seal. As another preferred embodiment, the seal is embedded, and the movement trajectory of the valve disc is controlled by a cam mechanism, causing the contact surface to transition from initial point contact to surface contact, gradually compressing the seal and enhancing its resistance to blow-out.

[0007] Furthermore, during the process of the valve disc rotating from the closed state to the open state, the outer surface of the valve disc gradually shifts toward the sealing element.

[0008] By designing the outer surface of the valve disc to offset towards the seal during rotation, a mechanism of gradual pressure increase is achieved, avoiding the seal from being subjected to instantaneous impact forces during high-pressure opening. The offset process ensures uniform force distribution on the seal, reducing the risk of tearing or displacement. Especially in emergency opening conditions, it buffers medium pressure, improving valve response stability and seal durability. As a preferred approach, the valve disc surface can be designed as an asymmetrical curved surface, guiding the offset through curvature changes during rotation. For example, as the valve disc begins to rotate from the closed position, its outer surface curvature gradually decreases, causing the contact point to move towards the center of the seal, generating a progressive clamping force. Another preferred approach is to implement the offset mechanism through a linkage mechanism, where the valve disc is connected to an adjustable arm. Driven by the valve stem, the arm swings, causing the outer surface of the valve disc to smoothly offset, ensuring the seal is always in a controlled compression state.

[0009] Furthermore, one end of the valve disc is provided with a valve stem for driving the valve disc to rotate, and the valve stem is an eccentric crankshaft; the other end of the valve disc is formed with a ball head, and a rotating seat is provided in the valve body corresponding to the ball head for the ball head to be inserted therein, and the rotating seat cooperates with the ball head to realize the rotation of the valve disc.

[0010] By cooperating with the eccentric crankshaft valve stem and the ball-head rotary seat, the valve disc is driven to swing and tilt during rotation, thereby reliably pressing the seal and solving the problem of seal loosening when the high pressure differential is opened. The eccentric crankshaft provides mechanical advantages, ensuring smooth valve disc movement and reducing vibration, while the ball-head rotary seat ensures rotational accuracy and maintains stable sealing contact under extreme conditions such as ultra-low temperature environments, preventing gap expansion caused by cold contraction. As a preferred option, the eccentric crankshaft can integrate a cam groove design. When the crankshaft rotates, the valve disc is guided by the groove to generate a compound motion, including rotation and axial displacement, so that the outer surface of the valve disc gradually presses against the seal. As another preferred option, the rotary seat adopts a ball-and-socket joint structure, with the ball head embedded in the seat and cooperating with a lubricated bushing. Driven by the valve stem, the ball head slides and rotates, achieving precise angle adjustment of the valve disc and ensuring that the offset process is free of jamming.

[0011] Furthermore, the valve seat includes a first mounting plate and a second mounting plate, and a placement groove for inserting a seal is formed between the first mounting plate and the second mounting plate. A notch is formed between the first mounting plate and the second mounting plate, and a portion of the seal protrudes from the notch and abuts against the outer surface of the valve disc.

[0012] By incorporating grooves and notches, the seal is mostly embedded within the groove with only a small portion exposed, enhancing its resistance to ejection. Under high-pressure media impact, the seal is less likely to be blown out or displaced, while ensuring effective contact with the valve disc. The notch design restricts the seal's freedom of movement; under cold contraction conditions, the groove exerts a stronger radial constraint on the seal, reducing the risk of loosening due to material shrinkage differences. As a preferred option, the mounting plate can be configured with barbed edges, forming a stepped structure on the inner wall of the groove. After installation, the barbs engage with the seal base, creating a self-locking effect under media pressure to prevent blow-out. Alternatively, the notch employs a tapered opening, with the exposed portion of the seal abutting against the valve disc through elastic pre-compression deformation. During valve operation, the notch edge provides lateral support, dispersing the peeling force.

[0013] Furthermore, the cross-sections of the outer surfaces of the first and second mounting plates facing the valve disc are connected to form a first virtual circle, and the cross-section of the portion of the seal exposed from the notch forms a second virtual circle. The second virtual circle mates with the outer diameter surface of the valve disc, and the first and second virtual circles become partially overlapping during the use of the valve disc.

[0014] The mating relationship between the first and second virtual circles provides a backup sealing mechanism. After the seal wears, the valve seat and valve disc directly contact metal-to-metal to form a secondary seal, ensuring long-term reliability. The initial tangential design ensures normal sealing, while the transition to partial overlap establishes a metal-to-metal seal to prevent media leakage, especially extending valve life under high wear or extreme operating conditions. As a preferred method, the surface of the mounting plate can be machined into an arc-shaped protrusion to match the exposed circular cross-section of the seal. During wear, the protrusion gradually contacts the spherical surface of the valve disc, achieving automatic compensation through geometric interference. As another preferred method, the virtual circle conversion mechanism is controlled by the valve disc's movement trajectory. When rotated to a specific angle, the surface of the mounting plate cuts into the sealing area, utilizing the elastic deformation of the material to transition to metal-to-metal contact, ensuring sealing continuity. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of an embodiment of the present utility model; Figure 2 This is a partial enlarged view of the contact position between the seal and the valve disc in an embodiment of this utility model; Figure 3 This is a schematic diagram of the virtual circle mating relationship in an embodiment of this utility model. Detailed Implementation

[0016] This utility model embodiment provides a sealing structure for a track ball valve as follows: Figure 1-3 As shown: The valve includes a valve body 1 and a spherical valve disc 2 disposed inside the valve body 1. The valve body 1 is a common pipe connection component, usually made of metal, used to contain and control fluid flow. A valve seat 3 is disposed within the valve body 1, which contacts the outer surface of the valve disc 2 to achieve a sealing function. A sealing element 4 is fixedly mounted on the valve seat 3. The sealing element 4 is usually made of an elastic material such as rubber or polytetrafluoroethylene, and its shape matches the outer surface of the valve disc 2 to ensure an effective seal is formed in the closed state.

[0017] The valve seat 3 consists of a first mounting plate 31 and a second mounting plate 32, which are fixed to the inner wall of the valve body 1 by bolts or welding. A placement groove 33 is formed between the first mounting plate 31 and the second mounting plate 32 to accommodate the seal 4. The placement groove 33 has a notch 34 between the first mounting plate 31 and the second mounting plate 32. A portion of the seal 4 protrudes from the notch 34 and abuts against the outer surface of the valve disc 2, thereby ensuring that most of the seal 4 is embedded in the placement groove 33 and preventing it from coming out under high pressure. The outer surface cross-sections of the first mounting plate 31 and the second mounting plate 32 facing the valve disc 2 are connected to form a first virtual circle 35, which is arc-shaped. The portion of the seal 4 protruding from the notch 34 forms a second virtual circle 42, which mates with the outer diameter surface of the valve disc 2. Under normal operating conditions, the two are tangent, and after wear, they can partially overlap to form a metal-to-metal contact seal.

[0018] One end of the valve disc 2 is connected to a valve stem 5, which is an eccentric crankshaft structure used to drive the valve disc 2 to rotate. The other end of the valve disc 2 forms a ball head 6, which is inserted into a rotating seat 7 provided inside the valve body 1. The rotating seat 7 is fixed to the valve body 1 by bearings or a sliding fit to achieve smooth rotation of the valve disc 2. During the process of the valve disc 2 rotating from the closed state to the open state, the outer surface of the valve disc 2 gradually shifts towards the sealing element 4, resulting in a gradual increase in the pressure against the sealing element 4, thereby preventing the sealing element 4 from dislodging under the impact of high-pressure media.

[0019] Working principle: During assembly, the sealing element 4 is first placed into the placement groove 33 of the valve seat 3, ensuring that part of it protrudes from the notch 34. Then, the ball head 6 of the valve disc 2 is inserted into the rotating seat 7 and connected to an external drive device such as a handwheel or motor via the valve stem 5. During operation, rotating the valve stem 5 causes the valve disc 2 to rotate 90° under the support of the rotating seat 7 due to the eccentric crankshaft design of the valve stem 5, while simultaneously swinging and tilting, causing the outer surface of the valve disc 2 to gradually press against the sealing element 4. During the rotation from the closed state to the open state, the offset of the outer surface of the valve disc 2 causes the pressure on the sealing element 4 to continuously increase, forming a reliable seal. After long-term use, if the sealing element 4 wears, the second virtual circle 42 and the first virtual circle 35 change from being tangent to partially overlapping, and the outer surface of the valve disc 2 directly contacts the surface of the valve seat 3, achieving a metal-to-metal hard contact seal.

[0020] 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 sealing structure for a ball valve, comprising a valve body and a spherical valve disc disposed within the valve body, wherein a valve seat is disposed within the valve body and contacts the outer surface of the valve disc, and a sealing element is disposed on the valve seat and mates with the outer surface of the valve disc, characterized in that: When the valve disc rotates from the closed state to the open state, the pressure of the outer surface of the valve disc against the seal gradually increases; the valve seat includes a first mounting plate and a second mounting plate, and a placement groove for inserting the seal is formed between the first mounting plate and the second mounting plate. A notch is formed between the first mounting plate and the second mounting plate, and part of the seal is exposed from the notch and abuts against the outer surface of the valve disc.

2. The sealing structure of the track ball valve according to claim 1, characterized in that: As the valve disc rotates from the closed state to the open state, the outer surface of the valve disc gradually shifts toward the sealing element.

3. The sealing structure of the track ball valve according to claim 2, characterized in that: One end of the valve disc is provided with a valve stem for driving the valve disc to rotate, and the valve stem is an eccentric crankshaft; the other end of the valve disc is formed with a ball head, and a rotating seat is provided in the valve body corresponding to the ball head for the ball head to be inserted therein. The rotating seat cooperates with the ball head to realize the rotation of the valve disc.

4. The sealing structure of the track ball valve according to claim 1, characterized in that: The cross-sections of the outer surfaces of the first and second mounting plates facing the valve disc are connected to form a first virtual circle. The cross-section of the part of the seal exposed from the notch forms a second virtual circle. The second virtual circle mates with the outer diameter surface of the valve disc. During the use of the valve disc, the first virtual circle and the second virtual circle change from being tangent to partially overlapping.

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