A sealing structure of a floating ball valve

Abstract

This utility model discloses a sealing structure for a floating ball valve, which is disposed on the ball valve body. A valve stem is provided inside the ball valve body, with the bottom end of the valve stem connected to the ball. The sealing structure includes a fixed ring, a compensating spring, and an elastic sealing ring. The fixed ring is fixed inside the ball valve body by threads or a step; the compensating spring is disposed between the fixed ring and the elastic sealing ring, in a pre-compressed state, applying an axial force towards the ball to the elastic sealing ring; the elastic sealing ring is sleeved on the outside of the valve stem, and its inner side has a main sealing lip and a secondary sealing lip, which respectively interfere with the outer wall of the ball and fit against the outer wall of the valve stem. The compensating spring is connected to the elastic sealing ring by circumferentially spaced support columns, ensuring uniform thrust. A graphite packing layer is located above the elastic sealing ring, consisting of three layers of flexible graphite rings stacked together and compressed by a packing gland. This structure can automatically compensate for sealing gaps when the medium pressure fluctuates, improving the dynamic sealing reliability of the valve stem area.

Description

Technical Field

[0001] This utility model relates to the field of floating ball valve technology, specifically to a sealing structure for a floating ball valve. Background Technology

[0002] Floating ball valves are widely used in industrial pipelines due to their compact structure and ease of operation. A typical structure includes a valve body, stem, ball, and seat, with the stem passing through the top of the valve body and rotating the ball to achieve opening and closing. To reduce media leakage along the gap between the stem and body, a sealing component, such as a packing seal or a resilient sealing ring, is usually placed around the stem.

[0003] However, in actual operation, industrial pipelines often experience medium pressure fluctuations due to pump start-up and shutdown, rapid valve switching, and other operations. These pressure fluctuations exert instantaneous radial forces on the elastic sealing elements near the valve stem, causing displacement or deformation. Especially when the elastic sealing ring needs to maintain contact with the ball to form an auxiliary seal, if it detaches from the ball surface due to pressure impact, a tiny gap will form between the sealing ring and the ball. The medium can seep into the gap between the valve stem and the valve body through this gap, ultimately causing external leakage.

[0004] In the existing technology, most floating ball valves rely on static pre-tightening or single packing seals, lacking a compensation mechanism to actively maintain the sealing ring and ball fit under dynamic pressure disturbances, making it difficult to meet the requirements of high reliability conditions. Utility Model Content

[0005] The purpose of this invention is to provide a sealing structure for a floating ball valve to solve the problem in the prior art where the elastic sealing ring fails to fit properly with the ball due to fluctuations in medium pressure, leading to leakage in the valve stem area.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a sealing structure for a floating ball valve, wherein the sealing structure is disposed on the ball valve body, the ball valve body is provided with a valve stem, and the bottom end of the valve stem is connected to a ball; the sealing structure includes a fixing ring, a compensating spring, and an elastic sealing ring; the fixing ring is fixed inside the ball valve body; the compensating spring is disposed between the fixing ring and the elastic sealing ring and is in a pre-compressed state, applying an axial force toward the ball to the elastic sealing ring; the elastic sealing ring is sleeved on the outside of the valve stem, and its inner side is provided with a sealing lip that abuts against the outer surface of the ball.

[0007] Furthermore, the ball valve body has a valve seat inside, which abuts against the ball.

[0008] Furthermore, the ball valve body has a graphite packing layer at the point where the valve stem passes through, the graphite packing layer is located above the elastic sealing ring, and a packing gland is provided on its outer side.

[0009] Furthermore, the elastic sealing ring and the fixing ring are provided with through holes for the valve stem to pass through, and the through holes are clearance-fitted with the valve stem.

[0010] Furthermore, the compensating spring is connected to the elastic sealing ring via multiple support columns, which are arranged at intervals along the circumference of the valve stem.

[0011] Furthermore, the elastic sealing ring is a stepped annular shape, with a main sealing lip and a secondary sealing lip on its inner ring. The main sealing lip is interference-fitted with the outer wall of the ball, and the secondary sealing lip is in contact with the outer wall of the valve stem.

[0012] Furthermore, the graphite filler layer is composed of three layers of flexible graphite rings stacked together.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] By setting a pre-compressed compensating spring between the fixed ring and the elastic sealing ring, the elastic sealing ring is always subjected to an axial compensating force toward the ball when the medium pressure fluctuates. Its sealing lip can continuously maintain a tight fit with the outer surface of the ball, which can reduce the leakage gap caused by the sealing ring detaching from the ball due to instantaneous pressure impact. This significantly improves the sealing reliability and service life of the floating ball valve under dynamic operating conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention;

[0016] Figure 2 This utility model Figure 1 Enlarged structural diagram at point A in the middle;

[0017] Figure 3 This is a three-dimensional structural diagram of the fixing ring of this utility model;

[0018] Figure 4 This is a schematic diagram of the internal structure of the fixing ring of this utility model.

[0019] In the diagram: 1. Ball valve body; 2. Valve seat; 3. Ball; 4. Sealing mechanism; 401. Packing gland; 402. Elastic sealing ring; 403. Fixing ring; 404. Graphite packing layer; 405. Support column; 406. Fitting groove; 407. Compensating spring; 5. Valve stem. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] Example:

[0022] Please see Figures 1 to 4 This embodiment provides a sealing structure for a floating ball valve, which is disposed on the ball valve body 1. A valve stem 5 is provided inside the ball valve body 1, and a ball 3 is connected to the bottom end of the valve stem 5. The sealing structure includes a retaining ring 403, a compensating spring 407, and an elastic sealing ring 402.

[0023] The retaining ring 403 is fixed inside the ball valve body 1 by a threaded connection or by engaging with the stepped surface of the inner wall of the ball valve body 1. Its axial position is reliably limited, preventing movement under medium pressure or spring reaction force. One end of the compensating spring 407 abuts against the end face of the retaining ring 403, and the other end abuts against the back end face of the elastic sealing ring 402. It is pre-compressed during assembly, thus applying a continuous axial force towards the ball 3 to the elastic sealing ring 402 in the initial state. The elastic sealing ring 402 is sleeved on the outside of the valve stem 5, and its central through hole is clearance-fitted with the valve stem 5, allowing the valve stem 5 to rotate freely while providing radial positioning. The inner side of the elastic sealing ring 402 is provided with a sealing lip, which forms an interference fit with the outer surface of the ball 3, maintaining tight contact under both static and dynamic conditions.

[0024] During operation, when the pressure of the medium in the pipeline fluctuates due to the start-up and shutdown of the pump or rapid switching of valves, the ball 3 may undergo slight displacement, resulting in a weakening of the contact force between it and the sealing lip. At this time, the compensating spring 407 releases some of its stored elastic potential energy, pushing the elastic sealing ring 402 to move axially along the valve stem 5 towards the ball 3, so that the sealing lip follows the position change of the ball 3 in real time and always remains in contact with its outer surface, thereby reducing the gap between them that could lead to media leakage.

[0025] It is worth noting that the ball valve body 1 has a valve seat 2 inside. The valve seat 2 is embedded in the annular mounting groove formed by the stepped structure on the inner wall of the ball valve body 1. The outer circumferential surface of the valve seat 2 is clearance-fitted with the inner wall of the ball valve body 1, or an O-ring is provided between the two to assist radial positioning and reduce media bypass. This installation method allows the valve seat 2 to have a certain degree of axial floating freedom, enabling it to undergo slight displacement under the action of media pressure.

[0026] The valve seat 2 has an annular sealing surface on the side facing the flow channel, which abuts against the outer surface of the ball 3. When the ball 3 rotates to the closed position, the upstream medium pressure acts on the back side of the ball 3, pushing the ball 3 towards the downstream valve seat 2, increasing the contact stress between the ball 3 and the valve seat 2, causing them to fit tightly together and form a reliable main sealing pair, thereby blocking the flow channel. This self-tightening sealing mechanism relies on the floating characteristics of the valve seat 2 and can maintain the integrity of the sealing interface under different pressure conditions.

[0027] Furthermore, the ball valve body 1 has a graphite packing layer 404 at the point where the valve stem 5 passes through. The graphite packing layer 404 has a ring structure, is arranged circumferentially around the valve stem 5, is located above the elastic sealing ring 402, and maintains contact with the outer surface of the valve stem 5. A packing gland 401 is disposed on the outside of the graphite packing layer 404, and its edge has a through hole. The packing gland 401 is firmly fixed to the ball valve body 1 by fastening bolts engaging with the threaded hole at the top of the ball valve body 1.

[0028] During assembly, as the fastening bolts are gradually tightened, the packing gland 401 applies a continuous axial compressive force to the graphite packing layer 404, compressing and filling the annular gap between the packing gland 401, the inner wall of the ball valve body 1, and the valve stem 5. Due to the good compressibility and resilience of the flexible graphite material, the graphite packing layer 404, under pressure, can tightly conform to the microscopic contours of the valve stem 5 surface and adapt to the slight swaying or vibration of the valve stem 5 during opening and closing, thereby forming a dynamic auxiliary seal for the valve stem 5 and preventing the leakage of trace amounts of media that may escape from the main sealing area.

[0029] In this embodiment, the elastic sealing ring 402 and the fixing ring 403 each have a through hole at their center. These through holes are arranged coaxially and are sized to allow the valve stem 5 to pass through. Specifically, a clearance fit is used between the inner wall of the through hole and the outer surface of the valve stem 5. This not only ensures that the valve stem 5 can rotate freely, but also acts as a throttling and blocking mechanism for the radial flow of the medium.

[0030] The resilient sealing ring 402 is typically made of a highly elastic material, such as rubber or polytetrafluoroethylene (PTFE), and its purpose is to provide the necessary sealing performance during valve stem 5 operation. When valve stem 5 passes through this ring, due to the elastic properties of the material, it can fit tightly against the surface of valve stem 5, thereby reducing media leakage.

[0031] The retaining ring 403 primarily serves a supporting and positioning function. It is typically made of metal or other rigid materials to enhance the structural strength of the entire sealing assembly. The design of the retaining ring 403 ensures the stability of the position of the elastic sealing ring 402, reducing displacement or deformation caused by external forces, thereby maintaining a long-term stable sealing effect.

[0032] It is worth noting that although the gap between the inner wall of the through-hole and the outer surface of the valve stem 5 allows for some radial flow, this design actually helps to create a dynamic sealing mechanism. Under this mechanism, as the valve stem 5 rotates, the medium is further compressed and moves slowly through the tiny gap, rather than forming an uncontrolled leakage path.

[0033] It should be noted that the compensating spring 407 is connected to the elastic sealing ring 402 via multiple support columns 405. The support columns 405 are arranged at intervals along the circumference of the valve stem 5. For example, four support columns 405 can be provided, evenly distributed at 90 degrees, and symmetrically distributed about the axis of the valve stem 5. Each support column 405 is a columnar structure, with one end fixed to the outer end face of the elastic sealing ring 402, and the other end abutting against or connected to the end ring of the compensating spring 407.

[0034] This arrangement ensures that when the compensating spring 407 releases its elastic potential energy, the axial thrust generated can be synchronously and evenly transmitted to the entire circumferential area of ​​the elastic sealing ring 402 through each support column 405. Due to the balanced thrust distribution, the possibility of the elastic sealing ring 402 tilting, jamming, or partially disengaging from the sealing surface of the sphere 3 due to uneven force distribution during movement is reduced. Simultaneously, the rigid structure of the support columns 405 provides stable guiding support for the compensating spring 407, reducing radial instability or buckling during compression or elongation, thereby improving the reliability and long-term stability of the sealing structure under dynamic operating conditions.

[0035] Furthermore, the elastic sealing ring 402 has a stepped annular structure, with its inner ring divided into two sealing areas of different heights along the axial direction. The inner ring edge near the ball 3 has a main sealing lip, which protrudes outwards and faces the ball 3, forming an interference fit with the outer wall of the ball 3. This pre-compression deformation occurs during assembly, ensuring reliable static sealing. The inner ring near the valve stem 5 has a secondary sealing lip, which extends radially and remains in contact with the outer wall of the valve stem 5, allowing the valve stem 5 to maintain continuous contact during rotation, achieving dynamic sealing.

[0036] Because the elastic sealing ring 402 is made of a highly elastic polymer material, the main sealing lip and the secondary sealing lip can adapt to the surface contour of the ball 3 and the slight deflection of the valve stem 5 after being compressed, thus maintaining the integrity of the sealing interface. This double-lip structure is spatially independent but functionally synergistic, forming two independent sealing lines at the ball 3 and valve stem 5 respectively, constituting a double sealing path, which can prevent the medium from penetrating from the sealing cavity to the valve stem area.

[0037] Furthermore, the graphite packing layer 404 is composed of three layers of flexible graphite rings stacked sequentially along the axial direction of the valve stem 5. Each layer of flexible graphite rings is an independent annular sheet structure, not connected by adhesive, and can slide relative to each other in a free state. When the packing gland 401 is fastened to the top of the ball valve body 1 by bolts, the applied axial clamping force compresses the three layers of flexible graphite rings and makes them fit tightly together, while simultaneously expanding radially to fill the annular gap between the valve stem 5 and the inner wall of the ball valve body 1.

[0038] Due to the excellent compressibility, resilience, and self-lubricating properties of flexible graphite materials, the graphite packing layer 404 can adapt to the microscopic roughness of the outer surface of the valve stem 5 under pressure, and adapt in real time to the slight wobble or axial movement of the valve stem 5 caused by assembly errors or thermal deformation during valve opening and closing. This dynamic fitting capability allows the sealing interface to maintain its integrity during operation, forming a self-adjusting sealing structure that requires no external intervention and can prevent the medium from escaping along the valve stem 5.

[0039] Working principle:

[0040] When the device is in use, the valve stem 5 drives the ball 3 to rotate to open or close the flow channel. When the pressure of the medium fluctuates due to the start-up or shutdown of the pump or rapid switching of the valve, the instantaneous change in pressure in the valve cavity may cause the ball 3 to undergo a slight displacement, resulting in a weakening of the fit between it and the elastic sealing ring 402.

[0041] At this time, the compensating spring 407, which is in a pre-compressed state, releases part of its elastic potential energy and transmits the axial thrust evenly to the elastic sealing ring 402 through the support column 405, pushing it to move axially along the valve stem 5 towards the ball 3. Under the action of the thrust, the main sealing lip of the inner ring of the elastic sealing ring 402 maintains an interference contact with the outer wall of the ball 3, while the secondary sealing lip simultaneously adheres to the outer wall of the valve stem 5, maintaining the integrity of the double sealing interface.

[0042] Meanwhile, the graphite packing layer 404 located above the elastic sealing ring 402 forms an auxiliary seal on the valve stem 5 under the axial clamping force of the packing gland 401, preventing trace amounts of media that might cross the elastic sealing ring 402 from leaking outwards. Thus, the entire sealing structure can maintain the sealing reliability of the valve stem area under dynamic operating conditions.

[0043] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0044] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sealing structure for a floating ball valve, the sealing structure being disposed on the ball valve body, characterized in that: The ball valve body is provided with a valve stem, and the bottom end of the valve stem is connected to a ball; The sealing structure includes a retaining ring, a compensating spring, and an elastic sealing ring; The retaining ring is fixed inside the ball valve body; The compensating spring is located between the fixed ring and the elastic sealing ring and is in a pre-compressed state, applying an axial force toward the sphere to the elastic sealing ring; The elastic sealing ring is sleeved on the outside of the valve stem, and its inner side is provided with a sealing lip that abuts against the outer surface of the ball.

2. The sealing structure of a floating ball valve according to claim 1, characterized in that: The ball valve body has a valve seat inside, and the valve seat abuts against the ball.

3. The sealing structure of a floating ball valve according to claim 2, characterized in that: The ball valve body has a graphite packing layer at the point where the valve stem passes through, the graphite packing layer is located above the elastic sealing ring, and a packing gland is provided on its outer side.

4. The sealing structure of a floating ball valve according to claim 3, characterized in that: The elastic sealing ring and the fixing ring are provided with through holes for the valve stem to pass through, and the through holes are clearance-fitted with the valve stem.

5. The sealing structure of a floating ball valve according to claim 4, characterized in that: The compensating spring is connected to the elastic sealing ring through multiple support columns, which are arranged at intervals along the circumference of the valve stem.

6. The sealing structure of a floating ball valve according to claim 5, characterized in that: The elastic sealing ring is a stepped ring with a main sealing lip and a secondary sealing lip on its inner ring. The main sealing lip is interference-fitted with the outer wall of the ball, and the secondary sealing lip is fitted with the outer wall of the valve stem.

7. The sealing structure of a floating ball valve according to claim 6, characterized in that: The graphite filler layer is composed of three layers of flexible graphite rings stacked together.

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