Valve rod mounting structure of gate valve

Abstract

The utility model discloses a valve rod mounting structure of a gate valve, which comprises a valve body, a gate plate, a valve rod, a valve cover, a hand wheel and the like, and is mainly characterized in that a radially raised convex ring is arranged in the middle of the valve rod, a limiting shoulder is arranged in an inner hole of the valve cover, and the upper surface of the convex ring is axially contacted and matched with the lower surface of the limiting shoulder to limit the valve rod from axially moving upwards and falling off. The hand wheel is positioned and installed at the upper end of the valve rod through the positioning shoulder, the bottom of the hand wheel abuts against the top face of the compression nut, under the condition that rotation of the hand wheel is not affected, once the valve rod moves downwards in the axial direction, the hand wheel can be driven to be abutted against and blocked by the compression nut, and therefore the valve rod is prevented from falling off due to the fact that the valve rod moves downwards in the axial direction. Obviously, according to the improved structure, due to the fact that traditional straining ring limiting is omitted, the number of parts is reduced, the assembling process is simpler, and the reliability of the using structure can be guaranteed; meanwhile, sealing parts such as filler do not need to be used for limiting, the aging speed of the sealing parts such as the filler is reduced, and the sealing performance is enhanced.

Description

Technical Field

[0001] This utility model relates to a valve stem mounting structure, specifically a valve stem mounting structure for a gate valve. Background Technology

[0002] Currently, one type of gate valve on the market operates by using a handwheel mounted on the upper end of the valve stem to drive the stem to rotate within the inner hole of the valve cover. This rotation then causes a gate plate, threaded to the lower end of the stem, to move up and down along the stem, sealing and opening / closing the valve. Clearly, this type of gate valve's stem structure is limited to rotation and thus restricts axial movement. To ensure rotational sealing, existing solutions primarily involve a radially protruding ring in the middle of the stem, restricting its axial movement to prevent the stem from detaching. For example, the "Gate Valve" in Chinese Patent Application No. 200920196228.7 primarily uses an inner shoulder on the lower surface of the ring to prevent upward axial movement and detachment, while the lower surface of the ring is restricted by a tight ring installed within the inner hole to prevent downward axial movement. The movement and detachment of this structure requires the additional installation of a tightening ring, which not only increases the number of parts but also the complexity of the installation structure. In particular, since the tightening ring is installed inside the valve cover, even if the installation becomes loose, it cannot be directly seen by the user, resulting in poor structural reliability. There is also a "stem-mounted gate valve" published in Chinese patent application number 201220406382.4, which restricts the lower surface of the convex ring by the upper surface of the inner shoulder in the inner hole to prevent axial downward movement and detachment. However, the upper surface of the convex ring is restricted by sealing components such as packing pressed between the valve stem and the inner hole to prevent axial upward movement and detachment. Since the sealing components such as packing have both a sealing function and a restrictive function, they are prone to accelerated aging, thereby affecting the rotational sealing performance of the valve stem. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a valve stem mounting structure for a gate valve that is simple to assemble, has a reliable structure, and good sealing performance.

[0004] The technical problem of this utility model is solved by the following technical solution:

[0005] A valve stem mounting structure for a gate valve includes a valve body with a medium passage; a gate, which is movable and height-adjustable within the valve body via guide structures on both sides; a valve cover, which is sealed and mounted on the top of the valve body; and a valve stem, which is rotatably and sealed within the inner hole of the valve cover, with its upper end extending through the valve cover and connected to a handwheel, and its lower end threadedly connected to the gate. When the valve stem rotates, the gate is moved up and down via threaded transmission. A clamping nut is provided on the top of the valve cover, and tightening the clamping nut compresses packing between the valve stem and the inner hole to form a rotational seal. A radially protruding ring is provided in the middle of the valve stem, and a limiting shoulder corresponding to the ring is provided in the inner hole. The upper surface of the ring and the lower surface of the limiting shoulder axially contact and engage to restrict the valve stem from axially moving upwards and falling off. The handwheel is positioned on the upper end of the valve stem via a positioning shoulder, and its bottom abuts against the top surface of the clamping nut, thereby restricting the valve stem from axially moving downwards and falling off.

[0006] The valve stem has a square shaft at its upper end and a positioning shoulder located below the square shaft. The handwheel drive is mounted on the square shaft and is blocked by the positioning shoulder to form a positioning installation.

[0007] The positioning shoulder is a radially protruding circular step, and the diameter of the positioning shoulder is larger than the outer diameter of the square shaft.

[0008] The inner surface of the inner hole and the outer surface of the valve stem form a rotational contact fit through a smooth cylindrical surface.

[0009] The inner surface of the inner hole is provided with an annular groove that surrounds the radial circumference. A sealing ring is provided in the annular groove, and the outer surface of the valve stem contacts the sealing ring to form a rotational seal.

[0010] The packing and sealing ring together form a double seal.

[0011] The aforementioned convex ring and positioning shoulder are both integrally formed on the valve stem.

[0012] The valve cover has a conical hole at the top, and the packing is pressed into the conical hole by a clamping nut and wraps around the valve stem in an annular shape to form a rotary seal.

[0013] Compared with the prior art, the present invention mainly features a radially protruding ring in the middle of the valve stem and a limiting shoulder in the inner hole of the valve cover corresponding to the ring. The upper surface of the ring and the lower surface of the limiting shoulder make axial contact to restrict the valve stem from moving upward and falling off. The handwheel is positioned on the upper end of the valve stem by the positioning shoulder and the bottom of the handwheel abuts against the top surface of the clamping nut. Without affecting the rotation of the handwheel, once the valve stem moves downward axially, the handwheel will be blocked by the clamping nut, thereby restricting the valve stem from moving downward and falling off. Clearly, the improved structure, by omitting the traditional retaining ring, reduces the number of parts, simplifies the assembly process, and ensures the reliability of the structure. Simultaneously, it eliminates the need for sealing components such as packing, reducing their aging rate and enhancing sealing performance. Furthermore, a radially circumferential annular groove can be provided on the inner surface of the valve cover's inner bore, where the valve stem is rotatably mounted. A sealing ring is placed within this groove to contact and rotate with the valve stem for sealing. This sealing ring, together with the packing, forms a double seal, significantly enhancing the valve stem's rotational sealing performance. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the present invention.

[0015] Figure 2 This is a sectional view of the valve stem.

[0016] Figure 3 This is a cross-sectional view of the valve cover. Detailed Implementation

[0017] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0018] like Figures 1-3 As shown, 1. Valve body, 2. Gate, 3. Valve stem, 31. Raised ring, 32. Locating shoulder, 33. External thread, 34. Square shaft, 4. Valve cover, 41. Inner hole, 42. Limiting shoulder, 43. Annular groove, 44. Tapered hole, 5. Compression nut, 6. Handwheel, 7. Packing, 8. Sealing ring.

[0019] A valve stem mounting structure for a gate valve, such as Figure 1 As shown, it is mainly applicable to the upgrading of gate valves in civil water supply, HVAC and other fields. Its structure includes valve body 1, gate 2, valve stem 3 and valve cover 4, etc.

[0020] The valve body 1 is provided with a medium channel for the medium to flow through; the gate 2 is installed in the valve body 1 with both sides being movable up and down through the guide structure. That is, the gate 2 is constrained by the guide structure and cannot rotate or translate, but can only move up and down. The guide structure can be a structure of guide groove and guide block.

[0021] The valve cover 4 is sealed and installed on the top of the valve body 1 by screwing it on. The valve cover 4 has an axial through-hole, that is, as shown in the figure. Figure 3 The inner hole 41 shown is vertically penetrating along the axis.

[0022] The valve stem 3 is rotatably and sealingly installed in the inner hole 41 of the valve cover 4, and the upper end of the valve stem passes through the valve cover 4 and connects to the handwheel 6. The lower end of the valve stem is threadedly connected to the internal threaded hole on the gate plate 2 through an external threaded shaft. In this way, the valve stem 3 can be rotated by the handwheel 6. Usually, when the valve stem rotates in the inner hole 41, the rotational motion can be converted into the movement of the gate plate 2 along the valve stem 3 by the threaded transmission and the guide structure. Thus, the opening and closing of the valve can be achieved by the movement of the gate plate 2.

[0023] The valve cover 4 is provided with a clamping nut 5 on the top, which is installed by screwing on the thread. By tightening the clamping nut, the packing 7 is pressed between the valve stem 3 and the inner hole 41, thereby forming a rotation seal of the valve stem 3. In this embodiment, a conical hole 44 is provided on the top of the valve cover 4, and the packing 7 is pressed into the conical hole 44 by the clamping nut 5, forming a rotation seal by wrapping the valve stem 3 in a ring. The conical hole structure also allows the clamping nut 5 to be tightened to adjust the sealing performance. For example, if the sealing performance of the packing 7 decreases with the use time, the tightening degree of the clamping nut 5 can be adjusted to improve the sealing performance again.

[0024] Furthermore, an annular groove 43 is provided on the inner surface of the inner bore 41, which is radially circumferentially surrounded. An O-ring 8 is installed in the annular groove, and the outer surface of the valve stem 3 can also form a rotational seal by contacting the sealing ring 8. In this way, the packing 7 and the sealing ring 8 can form a double-seal effect, which greatly enhances the rotational sealing performance of the valve stem 3. The sealing ring 8 is also located in the annular groove 43 of the inner bore 41, which allows the inner surface of the inner bore 41 and the outer surface of the valve stem 3 to form a rotational contact fit through a smooth cylindrical surface. This facilitates the smooth rotation of the valve stem 3 in the inner bore 41 and allows the annular groove to adopt a uniform size specification to adapt to different valve stem models, thereby achieving structural standardization.

[0025] Meanwhile, the valve stem 3 installed in the inner hole 41 will be restricted to move axially up and down to prevent it from falling off. Specifically, the valve stem has a radially protruding convex ring 31 in the middle, which is a frustum coaxial with the valve stem 3; the inner hole 41 has a limiting shoulder 42 corresponding to the convex ring 31, which is a circular step arranged radially around the inner surface of the inner hole 41; in this way, by axially contacting the upper surface of the convex ring 31 with the lower surface of the limiting shoulder 42, the axial upward movement of the valve stem 3 can be restricted to prevent it from falling off, that is, to prevent the valve stem 3 from moving axially upward and detaching from the inner hole 41.

[0026] The handwheel 6 is positioned on the upper end of the valve stem 3 via the positioning shoulder 32 on the valve stem 3, and the bottom of the handwheel 6 abuts against the top surface of the clamping nut 5. So, without affecting the rotation of the handwheel 6, once the valve stem 3 moves axially downward, it will cause the handwheel 6 to be abutted and blocked by the clamping nut 5, thereby limiting the axial downward movement of the valve stem 3 and preventing it from falling off, that is, preventing the valve stem 3 from moving axially downward and dislodging from the inner hole 41.

[0027] Of course, under normal circumstances, the handwheel 6 and the clamping nut 5 will be in a suitable position when installed. That is, when the bottom of the handwheel 6 abuts against the top surface of the clamping nut 5, a certain contact gap will be maintained to facilitate the rotation of the handwheel. If the sealing performance of the packing 7 decreases due to long-term use of the valve, and the handwheel 6 is driven by the valve stem 3 to press its bottom against the top surface of the clamping nut 5, thus affecting the rotation of the handwheel 6, it is usually only necessary to tighten the clamping nut 5. This can not only improve the sealing performance of the packing 7 again, but also loosen the contact friction between the bottom of the handwheel 6 and the top surface of the clamping nut 5.

[0028] The valve stem has an external thread 33 at its upper end, a square shaft 34 below the external thread 33, and a positioning shoulder 32 below the square shaft 34. The handwheel 6 is driven onto the square shaft 34 through the square hole at the shaft center and is blocked by the positioning shoulder 32 to form a positioning installation. Then, the handwheel 6 is fixed to the valve stem 3 by connecting the external thread 33 with the lock nut. Therefore, operating the handwheel 6 can drive the valve stem 3 to rotate.

[0029] The positioning shoulder 32 is a radially protruding circular step. The diameter of the positioning shoulder 32 must be larger than the outer diameter of the square shaft 34. The positioning shoulder 32 and the convex ring 31 are integrally formed on the valve stem 3 to ensure the structural strength of the valve stem.

[0030] This invention eliminates the traditional retaining ring, reducing the number of parts, simplifying the assembly process, ensuring the reliability of the structure, and eliminating the need for sealing components such as packing, thus reducing the aging rate of these components and enhancing sealing performance.

[0031] The basic principles and main features of this utility model have been described above. Those skilled in the art should understand that this utility model is not limited to the above embodiments. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the utility model as claimed. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A valve stem mounting structure for a gate valve, comprising: Valve body (1), which has a medium passage; Gate (2), which is mounted in the valve body on both sides via a guide structure; Valve cover (4), sealed and installed on top of valve body; The valve stem (3) is rotatably and sealingly installed in the inner hole (41) of the valve cover (4). Its upper end extends out of the valve cover and connects to the handwheel (6), and its lower end is threadedly connected to the gate plate (2). When the valve stem (3) rotates, it drives the gate plate (2) to rise and fall through the threaded transmission. The valve cover (4) is provided with a clamping nut (5) on top, and by tightening the clamping nut, the packing (7) is pressed between the valve stem (3) and the inner hole (41) to form a rotation seal. Its features are: The valve stem (3) is provided with a radially protruding ring (31) in the middle, and a limiting shoulder (42) corresponding to the ring (31) is provided in the inner hole (41). The upper surface of the ring and the lower surface of the limiting shoulder are axially contacted and fitted to restrict the valve stem (3) from moving upward and falling off. The handwheel (6) is positioned on the upper end of the valve stem (3) via the positioning shoulder (32) on the valve stem (3), and the bottom of the handwheel (6) abuts against the top surface of the clamping nut (5), thereby restricting the valve stem (3) from moving axially downward and falling off.

2. A valve stem mounting structure for a gate valve according to claim 1, wherein The valve stem (3) has a square shaft (34) at its upper end and a positioning shoulder (32) located below the square shaft. The handwheel (6) is mounted on the square shaft (34) and is blocked by the positioning shoulder (32) to form a positioning installation.

3. A valve stem mounting structure for a gate valve as defined in claim 2 wherein The positioning shoulder (32) is a radially protruding circular step, and the diameter of the positioning shoulder (32) is larger than the outer diameter of the square shaft (34).

4. The valve stem mounting structure for a gate valve according to claim 1, characterized by The inner surface of the inner hole (41) and the outer surface of the valve stem (3) form a rotational contact fit through a smooth cylindrical surface.

5. The valve stem mounting structure for a gate valve according to claim 1, wherein The inner surface of the inner hole (41) is provided with an annular groove (43) that surrounds the radial circumference. A sealing ring (8) is provided in the annular groove, and the outer surface of the valve stem (3) contacts the sealing ring (8) to form a rotation seal.

6. A valve stem mounting structure for a gate valve as defined in claim 5 wherein The packing (7) and the sealing ring (8) together form a double seal.

7. The valve stem mounting structure for a gate valve according to claim 1, wherein The convex ring (31) and the positioning shoulder (32) are both integrally formed on the valve stem (3).

8. The valve stem mounting structure of a gate valve according to claim 1, characterized by The valve cover (4) has a conical hole (44) at the top. The packing (7) is pressed into the conical hole (44) by the clamping nut (5) and wraps around the valve stem (3) in an annular shape to form a rotating seal.

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