A force transmission mechanism for preventing rotation of a valve stem and a valve

Abstract

The application relates to the technical field of valve design, in particular to a force transmission mechanism for preventing the rotation of a valve rod and a valve. The force transmission mechanism comprises a directional block sleeved on the valve rod, a key connection structure arranged on the directional block and the valve rod and adapted to limit the relative rotation of the directional block and the valve rod, a fastener arranged on the directional block and the valve rod and adapted to fix the directional block on the valve rod, and a guide structure arranged on a valve cover, wherein the directional block is provided with a limiting structure in sliding fit with the guide structure, so that the directional block moves in the axial direction. In the application, the directional block is sleeved on the valve rod, the relative rotation of the directional block and the valve rod is limited through the key connection structure, and the directional block is axially fixed on the valve rod through the fastener, so that the directional block and the valve rod form an integral assembly.

Description

Technical Field

[0001] This invention relates to the field of valve design technology, specifically to a force transmission mechanism that prevents valve stem rotation and a valve. Background Technology

[0002] In the field of valve technology, especially in gate valves and globe valves used in industrial pipeline systems, rotary motion is typically converted into linear motion of the valve stem via a drive device (such as a gearbox or handwheel) to raise and lower the valve disc, thereby controlling the flow of fluid. During this process, the valve stem needs to be circumferentially limited to prevent it from rotating with the valve stem nut, ensuring smooth axial movement of the valve stem.

[0003] In existing technologies, to achieve the anti-rotation function of the valve stem, a guide block is often connected to the valve stem via a pin. Specifically, the guide block and the valve stem are connected by a pin hole and a pin is inserted to restrict their relative rotation, while the pin also restricts axial relative displacement. However, burrs are easily generated in the pin hole during the fitting process. During secondary disassembly and assembly, these burrs may scratch the valve stem surface, affecting the sealing performance and service life of the valve stem. Summary of the Invention

[0004] In view of this, the present invention provides a force transmission mechanism and a valve that prevents the valve stem from rotating, so as to solve the problem that existing anti-rotation structures may scratch the surface of the valve stem.

[0005] In a first aspect, the present invention provides a force transmission mechanism for preventing valve stem rotation, wherein the valve stem is fitted inside a valve cover, comprising: A directional block is fitted onto the valve stem; A keyed connection structure is provided on the directional block and the valve stem, which is suitable for restricting the relative rotation of the two. Fasteners, provided on the guide block and valve stem, are suitable for fixing the guide block to the valve stem; A guide structure is provided on the valve cover, and the directional block is provided with a limiting structure that slides with the guide structure to allow the directional block to move axially.

[0006] In this application, a directional block is fitted onto the valve stem, and a keyed connection structure restricts relative rotation between the two. Fasteners then axially fix the directional block to the valve stem, forming an integral assembly. Simultaneously, a guide structure is provided on the valve cover, and a limiting structure on the directional block slides into the guide structure, thereby restricting the overall circumferential rotation of the assembly and allowing only axial movement. This separate keyed connection and fastener assembly replaces the traditional integrated pin connection, eliminating the need for on-site pin hole fabrication, avoiding burrs during pin hole fabrication, and resolving the risk of burrs scratching the valve stem surface during secondary disassembly and assembly. This effectively protects the valve stem's sealing surface and improves the valve's sealing reliability and overall service life after maintenance.

[0007] In one alternative embodiment, the key connection structure includes a first keyway disposed on the valve stem, a second keyway disposed on the directional block, and a key embedded between the two.

[0008] In this application, a first keyway is provided on the valve stem and a second keyway is provided on the guide block. The torque transmission and circumferential limiting between the valve stem and the guide block are achieved by embedding a key between the two. The use of an independent key as a connecting element allows the mating surface of the key and the keyway to withstand a large shear force, ensuring that there is no relative rotation between the valve stem and the guide block when the driving device applies torque, resulting in high transmission accuracy. At the same time, the key connection structure is a standardized mechanical connection method, which has the characteristics of easy control of machining accuracy and simple assembly, reducing manufacturing difficulty.

[0009] In one alternative embodiment, the fastener is a screw, the valve stem has a blind hole, the directional block has a threaded hole, and the screw is adapted to pass through the threaded hole and extend into the blind hole to fix the directional block to the valve stem.

[0010] In this application, screws are used as fasteners. After passing through the threaded hole on the guide block, the end of the screw extends into a pre-set blind hole on the valve stem, thereby axially fixing the guide block to the valve stem. The engagement of the screw and the blind hole ensures reliable positioning of the guide block and the valve stem in the axial direction, effectively preventing axial movement of the valve stem and guide block during vertical movement. Compared to traditional pin connections that require penetration through the valve stem or mating, this application uses a blind hole machined on the valve stem, which has less impact on the structural strength of the valve stem. Furthermore, the screw connection offers the advantage of repeated disassembly and assembly, allowing for convenient removal of the guide block during valve maintenance without damaging the valve stem.

[0011] In one alternative implementation, the first keyway is located on the opposite side of the blind hole.

[0012] In this application, the first keyway for mounting the key and the blind hole for accommodating the screw are positioned opposite each other in the circumferential direction of the valve stem, so that they are located at opposite ends in the diameter direction of the valve stem. This layout allows the torque load transmitted by the key connection and the axial load borne by the screw to be spatially separated, avoiding the overlap of stress concentration areas, optimizing the stress state of the valve stem, and utilizing the circumferential space of the valve stem to make the structure more compact. Within the limited internal space of the valve cover, it ensures that the functional components do not interfere with each other, improving the overall assembly coordination of the mechanism.

[0013] In one optional embodiment, the guiding structure is a guide rib disposed on the inner side of the valve cover, and the limiting structure is a slot disposed on the directional block, wherein the slot slides in conjunction with the guide rib.

[0014] In this application, guide ribs are provided on the inner side of the valve cover, and slots are formed on the directional block. The slots and guide ribs form a sliding fit pair, and the circumferential constraint of the guide ribs on the slots prevents the directional block from rotating. This forms a stable linear guide path, ensuring that the directional block maintains a precise axial trajectory during its up-and-down movement, thereby guaranteeing the smoothness of the valve stem's movement. This sliding fit structure has a large contact area and uniform force distribution, effectively withstanding the lateral forces that may be generated during valve opening and closing, avoiding jamming of the valve stem due to uneven force distribution, and improving the smoothness of valve operation.

[0015] In one alternative embodiment, the guide rib extends axially along the valve stem and is provided on one side.

[0016] In this application, a single-sided guide rib structure is adopted, which can reduce the processing complexity and manufacturing cost of the valve cover, while avoiding the over-positioning problem that may be caused by double-sided guidance. This allows the directional block to have a certain degree of automatic centering capability during movement, and also simplifies the assembly process. During installation, the slot and guide rib can be matched without strict alignment, which improves assembly efficiency. In addition, the single-sided structure helps to leave more space inside the valve cover, which is convenient for the arrangement and maintenance of other components.

[0017] Secondly, the present invention also provides a valve, comprising: Valve body, valve cover, valve disc, valve stem, drive device, and force transmission mechanism as described above to prevent the valve stem from rotating; The valve body has a fluid passage, the valve cover is connected to the valve body, the valve disc is disposed on the end side of the valve stem, and the driving device is adapted to apply torque to the valve stem so that the valve stem moves axially under the action of the force transmission mechanism.

[0018] In this application, the force transmission mechanism is integrated into the valve. The valve body provides a fluid passage, the valve cover is connected to the valve body, and the valve disc is located at the end of the valve stem. After the drive device applies torque to the valve stem, the valve stem cannot rotate but can only move axially under the restriction of the force transmission mechanism, thereby driving the valve disc to rise and fall. Through the integrated force transmission mechanism, the efficient conversion from the rotary input of the drive device to the linear output of the valve stem can be achieved, and the action response is direct. Since the force transmission mechanism does not require on-site installation, the overall valve assembly cycle is shortened, and the relevant components of the force transmission mechanism can be quickly disassembled and installed during maintenance after long-term use, reducing the maintenance cost of the valve.

[0019] In one alternative embodiment, the drive device includes a gearbox and a valve stem nut, the valve stem nut being connected to the valve stem via a threaded drive, and the gearbox being adapted to drive the valve stem nut to rotate, thereby causing the valve stem to move axially.

[0020] In this application, the gearbox drives the valve stem nut to rotate, and the valve stem nut drives the valve stem to move through a threaded transmission. Because the force transmission mechanism restricts the rotation of the valve stem, the threaded connection converts the rotational motion into the linear motion of the valve stem. Using a combination of gearbox and valve stem nut as the drive device allows the input torque to be amplified through the gearbox's reduction ratio, making operation more labor-saving.

[0021] In one alternative embodiment, the valve disc has a sealing surface between it and the valve body to close the fluid passage.

[0022] In this application, when the valve stem drives the valve disc to descend, the valve disc comes into close contact with the sealing surface on the valve body, thereby cutting off the fluid passage; when the valve stem drives the valve disc to rise, the sealing surface separates, and the fluid passage is opened. Because the force transmission mechanism ensures that the valve stem only moves axially and does not rotate circumferentially, the valve disc contacts the sealing surface at a constant orientation each time it descends. This avoids friction or uneven wear between the valve disc and the sealing surface caused by valve stem rotation, thus protecting the surface quality of the sealing surface, extending the service life of the sealing pair, and ensuring that the valve maintains reliable sealing performance even under frequent opening and closing conditions. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the oriented block structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the valve stem structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram showing the relative positions of the blind hole and the first keyway in an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures: 1. Valve stem; 2. Valve cover; 3. Directional block; 4. First keyway; 5. Second keyway; 6. Key; 7. Screw; 8. Blind hole; 9. Guide rib; 10. Slot; 11. Threaded hole. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the field of valve technology, especially in gate valves and globe valves used in industrial pipeline systems, rotary motion is typically converted into linear motion of the valve stem via a drive device (such as a gearbox or handwheel) to raise and lower the valve disc, thereby controlling the flow of fluid. During this process, the valve stem needs to be circumferentially limited to prevent it from rotating with the valve stem nut, ensuring smooth axial movement of the valve stem.

[0028] In existing technologies, to achieve the anti-rotation function of the valve stem, a guide block is often connected to the valve stem via a pin. Specifically, the guide block and the valve stem are connected by a pin hole, into which a pin is inserted to restrict their relative rotation, while the pin also restricts axial relative displacement. However, burrs are easily generated in the pin hole during the fitting process. During secondary disassembly and assembly, these burrs may scratch the valve stem surface, affecting the valve stem's sealing performance and service life. In existing technologies, the guide block and valve stem have a clearance fit of approximately 0.1 mm, while the pin has an interference fit with both the guide block and the valve stem. During drilling, the guide block and valve stem must pass through the pin. Burrs are generated on the intersection line during drilling. If these burrs are not cleaned properly, the inner hole of the guide block may scratch the valve stem surface during a second disassembly.

[0029] The following is combined with Figures 1 to 4 The following describes embodiments of the present invention.

[0030] Example 1 like Figures 1 to 4 As shown, the present invention provides a force transmission mechanism to prevent valve stem rotation, wherein the valve stem 1 is fitted inside the valve cover 2, and includes: The directional block 3 is fitted onto the valve stem 1; A keyed connection structure is provided on the directional block 3 and the valve stem 1, which is suitable for restricting the relative rotation of the two. Fasteners are provided on the directional block 3 and the valve stem 1, which are suitable for fixing the directional block 3 to the valve stem 1; A guide structure is provided on the valve cover 2, and the directional block 3 is provided with a limiting structure that slides with the guide structure so that the directional block 3 can move axially.

[0031] Specifically, the directional block 3 can be an annular structure with an inner diameter that matches the outer diameter of the valve stem 1. During assembly, it is directly fitted onto the outer circumferential surface of the valve stem 1. The keyed connection structure is achieved by machining a first keyway 4 on the outer circumferential surface of the valve stem 1 and a second keyway 5 on the inner wall of the directional block 3, with a key 6 simultaneously embedded in both keyway 6 slots. Fasteners can be screws 7. A blind hole 8 is machined at a corresponding position on the valve stem 1, and a threaded hole 11 is machined on the directional block 3. The screw 7 passes through the threaded hole 11 and its end extends into the blind hole 8, thus fixing the directional block 3 to the valve stem 1. The guide structure is integrally cast on the inner wall of the valve cover 2 or formed by machining. The limiting structure on the directional block 3 is formed by milling. During assembly, the limiting structure of the directional block 3 is aligned with the guide structure of the valve cover 2 and then slidably inserted.

[0032] In this application, the directional block 3 is fitted onto the valve stem 1, and the relative rotation between the two is restricted by a key connection structure. The directional block 3 is then axially fixed to the valve stem 1 by fasteners, forming an integral assembly with the valve stem 1. Simultaneously, the valve cover 2 has a guide structure, and the limiting structure on the directional block 3 slides in conjunction with the guide structure, thereby restricting the overall circumferential rotation of the assembly and allowing it to move only axially. The key 6 connection and the separate fastener connection replace the traditional integrated pin connection, eliminating the need for on-site pin hole fabrication, avoiding burrs during pin hole fabrication, and resolving the potential for burrs to scratch the surface of the valve stem 1 during secondary disassembly and assembly. This effectively protects the sealing surface of the valve stem 1 and improves the sealing reliability and overall service life of the valve after maintenance.

[0033] In one alternative embodiment, the key connection structure includes a first keyway 4 disposed on the valve stem 1, a second keyway 5 disposed on the directional block 3, and a key 6 embedded between the two.

[0034] Specifically, the first keyway 4 extends axially along the outer circumference of the valve stem 1 and is formed by milling. The length and width of the keyway 6 are designed according to the magnitude of the transmitted torque, and the two ends of the keyway 6 are set as semi-circular to eliminate stress concentration. The second keyway 5 is machined at the corresponding position on the inner wall of the guide block 3, and its dimensions match those of the first keyway 4. The key 6 is a standard flat key 6, and the material hardness is lower than that of the valve stem 1 and the guide block 3. During assembly, the key 6 is first embedded into the first keyway 4 of the valve stem 1, and then the guide block 3 is fitted from the end of the valve stem 1 so that the second keyway 5 is aligned with the position of the key 6. The key 6 is then fully inserted into the second keyway 5 by axial sliding.

[0035] In this application, a first keyway 4 is provided on the valve stem 1, and a second keyway 5 is provided on the directional block 3. The torque transmission and circumferential limiting between the valve stem 1 and the directional block 3 are achieved by embedding a key 6 between the two. The use of an independent key 6 as a connecting element allows the mating surface of the key 6 and the key 6 groove to withstand a large shear force, ensuring that there is no relative rotation between the valve stem 1 and the directional block 3 when the driving device applies torque, resulting in high transmission accuracy. At the same time, the key connection structure is a standardized mechanical connection method, which has the characteristics of easy control of machining accuracy and simple assembly, reducing manufacturing difficulty.

[0036] In one alternative embodiment, the fastener is a screw 7, the valve stem 1 is provided with a blind hole 8, the directional block 3 is provided with a threaded hole 11, and the screw 7 is adapted to pass through the threaded hole 11 and extend into the blind hole 8 to fix the directional block 3 to the valve stem 1.

[0037] Specifically, a circular blind hole 8 can be machined on the outer circumference of the valve stem 1. The depth of the blind hole 8 is determined according to the length of the screw 7, and the diameter of the blind hole 8 is slightly larger than the diameter of the end of the screw 7. The bottom of the blind hole 8 is tapered to facilitate the positioning of the end of the screw 7. A threaded hole 11 is machined on the guide block 3 at the position corresponding to the blind hole 8, and the threaded hole 11 penetrates the wall thickness of the guide block 3. The screw 7 is a hexagon socket head cap screw 7, with its head recessed into the outer surface of the guide block 3. During assembly, after the guide block 3 and the valve stem 1 are connected and positioned by the key 6, the screw 7 is screwed into the threaded hole 11 of the guide block 3 until the end of the screw 7 enters the blind hole 8 of the valve stem 1 and abuts against the bottom of the blind hole 8, thereby achieving axial locking.

[0038] In this application, screw 7 is used as a fastener. After passing through the threaded hole 11 on the guide block 3, the end of screw 7 extends into the pre-set blind hole 8 on the valve stem 1, thereby axially fixing the guide block 3 to the valve stem 1. The cooperation between screw 7 and blind hole 8 can achieve reliable positioning of guide block 3 and valve stem 1 in the axial direction, effectively preventing axial movement of valve stem 1 and guide block 3 during up and down movement. Compared with the traditional pin connection that requires penetrating valve stem 1 or mating, this application processes a blind hole 8 on valve stem 1, which has less impact on the structural strength of valve stem 1. Moreover, the screw 7 connection has the advantage of repeated disassembly and assembly, allowing convenient disassembly of guide block 3 during valve maintenance without damaging valve stem 1.

[0039] In one alternative implementation, the first keyway 4 is formed on the opposite side of the blind hole 8.

[0040] Specifically, during the machining of valve stem 1, the machining position of blind hole 8 can be determined first. Then, using the position of blind hole 8 as a reference, the first keyway 4 is machined on the circumferential surface of valve stem 1 at the opposite position along the diameter direction. The central axis of blind hole 8 and the center line of the first keyway 4 form a 180° angle on the cross-section of valve stem 1. This layout ensures that after assembly, the key connection structure and the screw 7 connection structure are located at opposite ends of the valve stem 1 along the diameter direction, completely separated in space and not overlapping. When valve stem 1 is subjected to torque and axial force, the stress areas of the two connection parts are independent of each other.

[0041] In this application, the first keyway 4 for mounting the key 6 and the blind hole 8 for accommodating the screw 7 are arranged opposite each other in the circumferential direction of the valve stem 1, so that they are located at both ends in the diameter direction of the valve stem 1. This layout allows the torque load transmitted by the key 6 and the axial load borne by the screw 7 to be spatially separated, avoiding the overlap of stress concentration areas, optimizing the stress state of the valve stem 1, and utilizing the circumferential space of the valve stem 1 to make the structure more compact. Within the limited internal space of the valve cover 2, it ensures that the functional components do not interfere with each other, improving the overall assembly coordination of the mechanism.

[0042] In one optional embodiment, the guiding structure is a guide rib 9 disposed on the inner side of the valve cover 2, and the limiting structure is a slot 10 disposed on the directional block 3, wherein the slot 10 is slidably engaged with the guide rib 9.

[0043] Specifically, the guide rib 9 can be integrally cast on the inner wall of the valve cover 2. Its cross-section is rectangular or trapezoidal, extending downwards from the top of the valve cover 2 to a set position along the axial direction of the valve cover 2. The sides and top of the guide rib 9 are machined to ensure surface roughness. The slot 10 on the directional block 3 is machined on the outer edge of the directional block 3 by milling. The width of the slot 10 matches the width of the guide rib 9, with a sliding gap reserved between them. The inner surface of the slot 10 is polished. During assembly, the slot 10 of the directional block 3 directly engages with the guide rib 9 of the valve cover 2, forming a sliding guide pair.

[0044] In this application, a guide rib 9 is provided on the inner side of the valve cover 2, and a groove 10 is formed on the directional block 3. The groove 10 and the guide rib 9 form a sliding fit pair. The circumferential constraint of the guide rib 9 on the groove 10 is used to prevent the directional block 3 from rotating. A stable linear guide path can be formed, so that the directional block 3 always maintains a precise axial trajectory during the up and down movement, thereby ensuring the smoothness of the valve stem 1's movement. This sliding fit structure has a large contact area and uniform force distribution, which can effectively withstand the lateral forces that may be generated during the valve opening and closing process, avoiding the jamming phenomenon of the valve stem 1 due to uneven force distribution, and improving the smoothness of valve operation.

[0045] In one alternative embodiment, the guide rib 9 extends axially along the valve stem 1 and is provided on one side.

[0046] Specifically, only one guide rib 9 can be provided on the inner wall of the valve cover 2. This guide rib 9 is located on one side of the inner wall of the valve cover 2, rather than being symmetrically arranged. The axial extension length of the guide rib 9 along the valve cover 2 is greater than the stroke length of the directional block 3. Only one slot 10 is provided on the directional block 3 at the position corresponding to the guide rib 9, and the opening direction of the slot 10 matches the protruding direction of the guide rib 9. During assembly, the directional block 3 forms a sliding fit with the single guide rib 9 on the valve cover 2 only through this one slot 10. The other outer edges of the directional block 3 maintain a gap with the inner wall of the valve cover 2, without any additional guiding constraints.

[0047] In this application, a single-sided guide rib 9 structure is adopted, which can reduce the processing complexity and manufacturing cost of the valve cover 2, while avoiding the over-positioning problem that may be caused by double-sided guidance. This allows the directional block 3 to have a certain automatic centering capability during movement, and also simplifies the assembly process. During installation, the slot 10 and the guide rib 9 can be matched without strict centering, which improves the assembly efficiency. In addition, the single-sided structure is conducive to leaving more space inside the valve cover 2, which is convenient for the arrangement and maintenance of other components.

[0048] Example 2 The present invention also provides a valve, comprising: Valve body, valve cover 2, valve disc, valve stem 1, drive device, and force transmission mechanism as described above to prevent the valve stem from rotating; The valve body has a fluid passage, the valve cover 2 is connected to the valve body, the valve disc is disposed on the end side of the valve stem 1, and the driving device is adapted to apply torque to the valve stem 1 so that the valve stem 1 moves axially under the action of the force transmission mechanism.

[0049] Specifically, the valve body and valve cover 2 are fastened together using middle flange studs and nuts, with a gasket between them for sealing. The valve stem 1 extends through the valve cover 2 into the valve body, and the valve disc is fixed to the end of the valve stem 1 by a valve disc cover. The force transmission mechanism is assembled between the valve stem 1 and the valve cover 2 as described above, with the directional block 3 located inside the valve cover 2. The output end of the drive device is connected to the valve stem nut, which is fitted onto the valve stem 1 and engages with it via a trapezoidal thread. During assembly, the force transmission mechanism is first installed in place, then the valve stem nut is screwed into the valve stem 1, and finally the gearbox is fixedly connected to the valve cover 2.

[0050] In this application, the force transmission mechanism is integrated into the valve. The valve body provides a fluid passage, the valve cover 2 is connected to the valve body, and the valve disc is located at the end of the valve stem 1. After the drive device applies torque to the valve stem 1, the valve stem 1 cannot rotate but can only move axially under the restriction of the force transmission mechanism, thereby driving the valve disc to rise and fall. Through the integrated force transmission mechanism, the efficient conversion from the rotary input of the drive device to the linear output of the valve stem 1 can be achieved, and the action response is direct. Since the force transmission mechanism does not require on-site installation, the overall valve assembly cycle is shortened, and the relevant components of the force transmission mechanism can be quickly disassembled and installed during maintenance after long-term use, reducing the maintenance cost of the valve.

[0051] In one optional embodiment, the drive device includes a gearbox and a valve stem nut, the valve stem nut being threadedly connected to the valve stem 1, and the gearbox being adapted to drive the valve stem nut to rotate, thereby causing the valve stem 1 to move axially.

[0052] Specifically, the gearbox can be fixedly installed on the top of the valve cover 2. A worm gear transmission pair or a bevel gear transmission pair is installed inside the gearbox, and the handwheel is connected to the input shaft. The valve stem nut is installed inside the gearbox, and its outer circumference is fixedly connected to the output gear of the gearbox. The inner hole of the valve stem nut has a trapezoidal internal thread. The upper part of the valve stem 1 has a trapezoidal external thread that mates with the valve stem nut. During assembly, the valve stem 1 passes through the valve stem nut, forming a transmission fit through the threaded pair. During operation, rotating the handwheel drives the gear inside the gearbox to rotate, which in turn drives the valve stem nut to rotate. Because the circumferential rotation of the valve stem 1 is restricted by the force transmission mechanism, the valve stem 1 moves axially in a linear motion along the thread.

[0053] In this application, the gearbox drives the valve stem nut to rotate, and the valve stem nut drives the valve stem 1 to move through a threaded transmission. Since the force transmission mechanism restricts the rotation of the valve stem 1, the threaded connection converts the rotational motion into the linear motion of the valve stem 1. By using a combination of gearbox and valve stem nut as the driving device, the input torque can be amplified through the reduction ratio of the gearbox, making operation more labor-saving.

[0054] In one alternative embodiment, the valve disc has a sealing surface between it and the valve body to close the fluid passage.

[0055] Specifically, a valve seat can be installed within the fluid passage of the valve body. The valve seat is integrally cast with the valve body or machined by welding. The sealing surface of the valve seat is hardened and ground to a specified surface roughness. The sealing surface of the valve disc uses a material and hardness matching the sealing surface of the valve seat, and precision machining ensures a good fit between the two. During assembly, the valve disc is fixed to the end of the valve stem 1. When the valve stem 1 descends to the lower limit position, the sealing surface of the valve disc and the sealing surface of the valve seat are tightly fitted together, forming a hard metal seal. When the valve stem 1 rises, the sealing surface of the valve disc separates from the sealing surface of the valve seat, opening the fluid passage.

[0056] In this application, when the valve stem 1 drives the valve disc to descend, the valve disc comes into close contact with the sealing surface on the valve body, thereby cutting off the fluid passage; when the valve stem 1 drives the valve disc to rise, the sealing surface separates, and the fluid passage is opened. Because the force transmission mechanism ensures that the valve stem 1 only moves axially and does not rotate circumferentially, the valve disc can contact the sealing surface in a constant orientation each time it descends. This avoids friction or uneven wear between the valve disc and the sealing surface caused by the rotation of the valve stem 1, thus protecting the surface quality of the sealing surface, extending the service life of the sealing pair, and ensuring that the valve maintains reliable sealing performance even under frequent opening and closing conditions.

[0057] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A force transmission mechanism for preventing valve stem rotation, wherein the valve stem (1) is fitted inside a valve cover (2), characterized in that, include: The directional block (3) is fitted onto the valve stem (1); A key connection structure is provided on the directional block (3) and the valve stem (1) to restrict their relative rotation; Fasteners are provided on the directional block (3) and the valve stem (1) to fix the directional block (3) on the valve stem (1); A guide structure is provided on the valve cover (2), and the directional block (3) is provided with a limiting structure that slides with the guide structure so that the directional block (3) can move axially.

2. The force transmission mechanism for preventing valve stem rotation according to claim 1, characterized in that, The key connection structure includes a first keyway (4) on the valve stem (1), a second keyway (5) on the directional block (3), and a key (6) embedded between the two.

3. The force transmission mechanism for preventing valve stem rotation according to claim 2, characterized in that, The fastener is a screw (7), the valve stem (1) is provided with a blind hole (8), the directional block (3) is provided with a threaded hole (11), the screw (7) is adapted to pass through the threaded hole (11) and extend into the blind hole (8) to fix the directional block (3) on the valve stem (1).

4. The force transmission mechanism for preventing valve stem rotation according to claim 3, characterized in that, The first keyway (4) is located on the opposite side of the blind hole (8).

5. The force transmission mechanism for preventing valve stem rotation according to claim 1, characterized in that, The guiding structure is a guide rib (9) set inside the valve cover (2), and the limiting structure is a slot (10) set on the directional block (3). The slot (10) and the guide rib (9) slide together.

6. The force transmission mechanism for preventing valve stem rotation according to claim 5, characterized in that, The guide rib (9) extends axially along the valve stem (1) and is provided on one side.

7. A valve, characterized in that, include: Valve body, valve cover (2), valve disc, valve stem (1), drive device, and force transmission mechanism for preventing valve stem rotation as described in any one of claims 1 to 6; The valve body has a fluid passage, the valve cover (2) is connected to the valve body, the valve disc is disposed on the end side of the valve stem (1), and the driving device is adapted to apply torque to the valve stem (1) so that the valve stem (1) moves axially under the action of the force transmission mechanism.

8. The valve according to claim 7, characterized in that, The drive device includes a gearbox and a valve stem nut. The valve stem nut is connected to the valve stem (1) by a threaded transmission. The gearbox is adapted to drive the valve stem nut to rotate so as to drive the valve stem (1) to move axially.

9. The valve according to claim 7, characterized in that, The valve disc has a sealing surface between it and the valve body to close the fluid passage.

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