Valve rod sealing assembly and ball valve

Abstract

The utility model belongs to the technical field of valves, and relates to a valve rod sealing assembly and a ball valve.The valve rod sealing assembly is provided with a valve deck (1) and a valve rod (2), the valve rod (2) is arranged in a stuffing box hole of the valve deck (1) in a penetrating mode, and a first stuffing assembly (3), a stuffing spacer ring (4) and a second stuffing assembly (5) are sequentially placed between the valve rod (2) and the stuffing box hole from bottom to top; a limiting part is arranged in the stuffing box hole and is used for limiting the moving distance of the stuffing spacer ring (4) towards the bottom of the stuffing box hole; and the filler pressing plate (7) provides pre-tightening force for the first filler assembly (3) and the second filler assembly (5). The limiting part in the stuffing box hole is used for limiting the distance of the stuffing spacer ring (4) moving towards the bottom of the stuffing box hole, so that the valve rod (2) and the valve cover (1) are subjected to double sealing, quantitative compression of each stuffing assembly is achieved, the situation that one of the stuffing assemblies is too large in deformation quantity is avoided, and the service life of the stuffing assemblies is prolonged on the premise that the sealing performance is guaranteed.

Description

Technical Field

[0001] The present application belongs to the technical field of valves, and in particular relates to a valve stem sealing assembly and a ball valve. Background Art

[0002] Ball valves, used to control the flow of pipelines, are widely used in various fields due to their low flow resistance and excellent sealing performance. However, some ball valves may contain toxic and hazardous media, or easily dissipated small molecules. How to seal the ball valve stem to prevent the leakage of these toxic or easily dissipated media has become a concern for technical personnel. Utility Model Content

[0003] The present application provides a valve stem sealing assembly, which is provided with a valve cover and a valve stem, wherein the valve stem is inserted into a stuffing box hole of the valve cover, and comprises:

[0004] A first packing assembly, a packing spacer ring, and a second packing assembly are placed between the valve stem and the stuffing box hole from bottom to top;

[0005] A limiting portion is provided in the stuffing box hole, and the limiting portion is used to limit the distance that the stuffing spacer ring moves toward the bottom of the stuffing box hole;

[0006] A packing pressure plate is connected to the top of the valve cover to provide pre-tightening force for the first packing assembly and the second packing assembly.

[0007] Furthermore, the first packing component is a plurality of stacked packings made of polytetrafluoroethylene, in annular shape, and with a V-shaped cross-section.

[0008] Furthermore, the second filler component is a special-shaped filler made of graphite.

[0009] Furthermore, the stuffing box hole includes a first aperture section and a second aperture section in sequence from bottom to top, and the diameter of the first aperture section is smaller than that of the second aperture section;

[0010] The first aperture section is filled with the first filler component, and the second aperture section is filled with the second filler component;

[0011] The second outer diameter section of the packing spacer ring is arranged in the second aperture section and is adapted to the inner wall thereof.

[0012] Furthermore, the packing spacer ring has a first outer diameter section on a side facing the first packing component, and the first outer diameter section is adapted to the inner wall of the first aperture section.

[0013] Furthermore, the limiting portion is provided at a step between the first aperture section and the second aperture section of the stuffing box hole, and the step between the first aperture section and the second aperture section has a valve cover step limiting surface;

[0014] A packing spacer ring limiting surface is provided at the step between the first outer diameter section and the second outer diameter section of the first packing component;

[0015] There is a preset distance between the initial assembly position of the valve cover step limiting surface and the packing spacer ring limiting surface.

[0016] Furthermore, the stuffing box hole includes a plurality of variable diameter hole segments, each hole segment is filled with fillers of different materials or shapes, and packing spacer rings are provided between adjacent packing components.

[0017] Furthermore, the valve stem sealing assembly further comprises a packing gland and a packing gland liner;

[0018] The packing pressing sleeve is arranged between the packing pressing plate and the second packing assembly and is slidably connected to the stuffing box hole;

[0019] The packing gland liner is arranged on the inner side of the packing gland and is slidably connected to the valve stem.

[0020] Furthermore, the valve stem sealing assembly also includes: a plurality of slipknot bolts, one end of each slipknot bolt is hinged to the hanging ear provided on the top of the valve cover, and the other end is connected to the packing pressure plate through a nut.

[0021] On the other hand, the present invention proposes a ball valve, including a valve body, a valve ball and a valve stem sealing assembly described in any of the above technical solutions, the valve cover is adapted to the valve body to enclose the valve ball inside, and the valve stem is inserted into the stuffing box hole of the valve cover and is used to control the valve ball.

[0022] The above technical solution of the utility model has at least the following beneficial technical effects:

[0023] The first packing assembly and the second packing assembly of the present application provide a double seal for the valve stem, and the limiting portion in the stuffing box hole is used to limit the distance that the packing spacer ring moves toward the bottom of the stuffing box hole, so that the valve stem and the valve cover are doubly sealed while achieving quantitative compression of each packing assembly, avoiding excessive deformation of one of the packing assemblies, and extending the service life of the packing assembly while ensuring the sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a cross-sectional view of a valve stem sealing assembly in one embodiment of the present application.

[0026] Figure 2 It is a cross-sectional view of a portion D of a valve stem sealing assembly in one embodiment of the present application.

[0027] in, Figures 1 to 2 The corresponding relationship between the reference numerals and component names is as follows:

[0028] 1. Bonnet; 101. First aperture section; 102. Second aperture section; 2. Valve stem; 3. First packing assembly; 4. Packing spacer; 401. First outer diameter section; 402. Second outer diameter section; 5. Second packing assembly; 6. Packing gland; 6-1. Packing gland liner; 7. Packing plate; 8. Slip bolt; 9. Nut; 10. Disc spring; A. Packing spacer limiting surface; B. Bonnet step limiting surface; Part D. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined with each other and referenced to each other under the premise of no contradiction.

[0030] This application mainly solves the sealing problem between the valve stem 2 and the valve cover 1 of the valve, such as Figure 1 As shown, in one embodiment, a valve stem sealing assembly is provided, which includes a valve cover 1 and a valve stem 2. The valve stem 2 is disposed in the stuffing box hole of the valve cover 1. It should be noted that in the overall structure of the valve, the valve cover 1 is connected to the valve body to seal the valve ball therein, and the valve stem 2 is connected to the valve ball and is used to control its rotation to achieve the opening and closing effect of the valve. The valve stem sealing assembly of the present application specifically includes:

[0031] The stuffing box hole is inside the valve cover 1 and has an inner wall and an annular bottom wall. After the valve stem 2 is inserted into the stuffing box hole of the valve cover 1, the first stuffing assembly 3, the stuffing spacer ring 4 and the second stuffing assembly 5 are filled in sequence from the bottom to the top of the stuffing box hole; wherein, the first stuffing assembly 3 and the second stuffing assembly 5 are made of different materials or have different structures.

[0032] Since the first packing component 3 and the second packing component 5 are made of different materials or structures, the deformation amounts generated under the same pressure are different. In order to avoid that the deformation amount of one of them is too large and affects the sealing, or that the sealing effect of the other packing component is reduced due to excessive wear of one of them, the packing pressure plate 7 of the present application is connected to the top of the valve cover 1 to provide pre-tightening force for the first packing component 3 and the second packing component 5, and a limiting portion is provided on the inner wall of the stuffing box hole to limit the distance that the packing spacer ring 4 moves toward the bottom of the stuffing box hole, so that the valve stem 2 and the valve cover 1 are doubly sealed while achieving quantitative compression of each packing component, thereby extending the service life of the packing component while ensuring the sealing performance.

[0033] In one embodiment, the material used for the first packing component 3 is polytetrafluoroethylene (PTFE), and is composed of a plurality of annular, V-shaped first packings stacked together, and the V-shaped opening directions of all or part of the first packings remain consistent. PTFE has the advantages of low friction coefficient and self-lubrication, and is suitable for rotary valve stem 2. The force indirectly applied to the first packing component 3 by the packing pressure plate 7 will cause the V-shaped mouth to have a tendency to continue to open, squeezing the valve stem 2 inside and the stuffing box hole outside, which is beneficial to the seal between the valve stem 2 and the stuffing box hole of the valve cover 1. Preferably, the V-shaped mouths of the first packing component 3 are all arranged toward the bottom of the stuffing box hole, which can achieve a better sealing effect, and is particularly suitable for preventing the escape of small molecular gases such as hydrogen. The V-shaped first packing component 3 acts as the main seal, and under the combined action of the downward preload force provided by the packing spacer ring 4 and the upward elastic force provided by the medium force, a reliable seal between the valve cover 1 and the valve stem 2 can be ensured.

[0034] Optionally, the second stuffing assembly 5 is a tension seal ring, and is installed with its opening facing the bottom of the stuffing box hole, which can achieve a better sealing effect.

[0035] In one embodiment, the material used for the second packing component 5 is graphite, preferably flexible graphite, and graphite sealing has good fireproof and heat-insulating effects. The second packing component 5 is composed of a plurality of special-shaped second packings of different shapes. Special-shaped packing means that the outer shape of a single second packing is not limited to a specific shape, but a plurality of second packings are stacked to form the second packing component 5. The second packing component 5 is annular, and the cross-sectional shape and size are uniform. Preferably, the cross-section of the end rings at the upper and lower ends is rectangular, and the height and width are uniform, which plays a basic support and sealing role. The cross-section of the 3-5 graphite packings in the middle is special-shaped, which is easy to deform and easier to achieve sealing. The materials and structures of the first packing component 3 and the second packing component 5 can achieve pressure self-tightening. The greater the pressure, the better the sealing effect.

[0036] In one embodiment, if Figure 2As shown in the partial D of the valve cover, the stuffing box hole includes, from bottom to top, a first aperture section 101 and a second aperture section 102 of different diameters. The diameter of the first aperture section 101 is smaller than that of the second aperture section 102. The two aperture sections are transitionally connected by the valve cover step limit surface B to form a stepped shape. The first aperture section 101 is filled with the first packing assembly 3, and the second aperture section 102 is filled with the second packing assembly 5.

[0037] Corresponding to the diameter of the stuffing box hole, the packing spacer ring 4 is provided with a first outer diameter section 401 and a second outer diameter section 402, which are transitionally connected by the packing spacer ring limiting surface A; the second outer diameter section 402 is adapted to the inner wall of the second aperture section 102 of the stuffing box hole, and the first outer diameter section 401 is adapted to the inner wall of the first aperture section 101.

[0038] Preferably, the stuffing box aperture's limiting portion includes a valve cover step limiting surface B. A preset clearance exists between this limiting surface and the opposing packing spacer ring limiting surface A. This preset distance is less than the length of the first outer diameter section 401 of the packing spacer ring 4, ensuring that a portion of the first outer diameter section 401 remains within the stuffing box aperture's first aperture section 101. This preset clearance exists during initial assembly and can gradually decrease or become zero as the ball valve is used. When the packing spacer ring limiting surface A contacts the valve cover step limiting surface B, the limiting surface is retained, causing the packing assembly to be quantitatively compressed, thereby extending the packing's service life while maintaining sealing performance.

[0039] Optionally, the stuffing box hole includes multiple variable diameter hole sections, and each two adjacent hole sections are filled with packing components of different materials or structures, and packing spacer rings 4 are arranged between adjacent packing components; the corresponding adjacent variable diameter hole sections are transitionally connected by the valve cover step limiting surface B, and each packing spacer ring 4 is set to two sections, the outer diameters of the two sections are different, and they are connected by the packing spacer ring limiting surface A; so as to achieve quantitative compression in each hole section.

[0040] In one embodiment, the limiting portion in the stuffing box hole can be an annular limiting groove opened in the middle section of its inner wall, and the stuffing spacer ring 4 is an open ring. After the open ring is installed into the limiting groove, it can only move between the two end faces of the annular limiting groove, so that the upper and lower stuffing components can be quantitatively compressed.

[0041] In one embodiment, the valve stem sealing assembly further includes a packing sleeve 6 and a packing sleeve liner 6-1; the packing sleeve 6 is arranged between the packing pressure plate 7 and the second packing assembly 5, and is slidably connected to the stuffing box hole, ensuring the top seal while applying pressure to the second packing assembly 5; the packing sleeve liner 6-1 is arranged on the inner side of the packing sleeve 6, and is made of reinforced PTFE material. It is slidably connected to the valve stem 2, and plays an auxiliary positioning role for the valve stem 2, ensuring the centering of the valve stem 2, and reducing the wear of the packing assembly caused by eccentric wear of the valve stem 2.

[0042] In one embodiment, a plurality of lugs are provided around the top of the valve cover 1. The valve stem sealing assembly further comprises a plurality of slip bolts 8, each of which is hingedly connected to a lug at one end and connected to the packing plate 7 at the other end via a nut 9. A disc spring 10 is also installed between the nut 9 and the packing plate 7. Preferably, the disc spring 10 comprises two pieces, which are preloaded by tightening the nut 9 to compensate for wear of the packing assembly after long-term use. During initial assembly, the disc spring 10 reserves a certain amount of preload force due to the tightening of the nut 9. When the graphite of the second packing assembly 5 is worn, the disc spring 10 releases the preload force and continues to compress the second packing assembly 5, providing effective elastic compensation.

[0043] On the other hand, the present invention proposes a ball valve, including a valve body, a valve ball and a valve stem sealing assembly in any of the above technical solutions. The valve cover 1 is adapted to the valve body to enclose the valve ball inside, and the valve stem 2 is inserted into the stuffing box hole of the valve cover 1 and is used to control the valve ball.

[0044] It should be understood that the above-mentioned specific embodiments of the present application are merely illustrative or explain the principles of the present application and do not constitute a limitation of the present application. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present application should be included in the scope of protection of the present application. In addition, the claims attached hereto are intended to cover all variations and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A valve stem sealing assembly, comprising a valve cover (1) and a valve stem (2), wherein the valve stem (2) is inserted into a stuffing box hole of the valve cover (1), and characterized in that: include: A first packing assembly (3), a packing spacer ring (4) and a second packing assembly (5) are placed between the valve stem (2) and the stuffing box hole in sequence from bottom to top; A limiting portion is provided in the stuffing box hole, and the limiting portion is used to limit the distance that the stuffing spacer ring (4) moves toward the bottom of the stuffing box hole; A packing pressure plate (7) is connected to the top of the valve cover (1) to provide pre-tightening force for the first packing assembly (3) and the second packing assembly (5).

2. The valve stem seal assembly according to claim 1, wherein: The first packing component (3) is a plurality of stacked packings made of polytetrafluoroethylene, annular, and V-shaped in cross section.

3. The valve stem seal assembly according to claim 1, wherein: The second filler component (5) is a special-shaped filler made of graphite.

4. The valve stem seal assembly according to claim 1, wherein: The stuffing box hole comprises a first aperture section (101) and a second aperture section (102) in sequence from bottom to top, wherein the diameter of the first aperture section (101) is smaller than that of the second aperture section (102); The first aperture section (101) is filled with the first filler component (3), and the second aperture section (102) is filled with the second filler component (5); The second outer diameter section (402) of the packing spacer ring (4) is arranged in the second aperture section (102) and is adapted to the inner wall thereof.

5. The valve stem seal assembly according to claim 4, wherein: The packing spacer ring (4) has a first outer diameter section on a side facing the first packing component (3), and the first outer diameter section is adapted to the inner wall of the first aperture section (101).

6. The valve stem seal assembly according to claim 5, wherein: The limiting portion is arranged at a step between a first aperture section (101) and a second aperture section (102) of the stuffing box hole, and the step between the first aperture section (101) and the second aperture section (102) has a valve cover step limiting surface (B); A packing spacer ring limiting surface (A) is provided at the step between the first outer diameter section (401) and the second outer diameter section (402) of the first packing component (3); There is a preset distance gap between the valve cover step limiting surface (B) and the packing spacer ring limiting surface (A) at the initial assembly position.

7. The valve stem seal assembly according to claim 1, wherein: The stuffing box hole comprises a plurality of variable diameter hole sections, each hole section is filled with a stuffing component of different material or shape, and a stuffing spacer ring (4) is provided between adjacent stuffing components.

8. The valve stem seal assembly according to claim 1, wherein: It also includes a packing gland (6) and a packing gland liner (6-1); The packing pressing sleeve (6) is arranged between the packing pressing plate (7) and the second packing assembly (5), and is slidably connected to the packing box hole; The packing gland lining (6-1) is arranged on the inner side of the packing gland (6) and is slidably connected to the valve stem (2).

9. The valve stem seal assembly according to claim 1, wherein: Also includes: A plurality of live bolts (8), one end of each live bolt (8) is hinged to a hanging ear provided on the top of the valve cover (1), and the other end is connected to a packing pressure plate (7) via a nut (9).

10. A ball valve, characterized in that: The invention comprises a valve body, a valve ball and a valve stem sealing assembly as described in any one of claims 1 to 9, wherein the valve cover (1) is adapted to the valve body to enclose the valve ball therein, and the valve stem (2) is passed through the stuffing box hole of the valve cover (1) and is used to control the valve ball.

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