Rail type ball valve cam structure

Abstract

The utility model discloses a track type ball valve cam structure which comprises a valve rod, a cam shaft, a cam shaft and a cam shaft, the ball body is connected with the valve rod; the pin shaft is arranged between the flat structure of the valve rod and the ball body; the sliding bearings are respectively arranged at two ends of the pin shaft and are connected with the ball body; wherein the pin shaft is rotatably connected with the ball body through the sliding bearing, so that the contact point of the pin shaft and the valve rod is dynamically changed in the opening and closing process of the valve. The sliding bearings are additionally arranged at the two ends of the pin shaft, the contact between the pin shaft and the valve rod is changed into rolling friction from sliding friction, the service life of the pin shaft is remarkably prolonged through the design, and the overall reliability and operation stability of the valve are improved. In addition, due to the modular structural design, the maintenance cost is reduced, the downtime is shortened, and the ball valve can keep good adaptability and operate efficiently under various harsh working conditions.

Description

Technical Field

[0001] The utility model relates to the technical field of ball valve manufacturing, in particular to a track type ball valve cam structure. Background Art

[0002] The original design of the orbital ball valve aimed to facilitate machining, assembly, and replacement of the valve stem and ball. However, long-term use revealed several issues with the traditional pin-type mechanism. The operating principle of the existing orbital ball valve is as follows: a cam mechanism disengages the valve ball from the valve seat during rotation. Once fully rotated, the ball is pushed toward the valve seat, achieving a seal. When the valve is fully open, turning the handwheel causes the valve stem to descend, driving the ball to rotate. The precision helical groove on the valve stem interacts with the guide pin embedded in the bracket, driving the ball to rotate continuously clockwise along with the valve stem. When the valve is about to close, the valve stem rotates the ball 90°, completely frictionless against the valve seat. Further turning of the handwheel causes the valve stem to descend again, mechanically compressing the ball via the cam mechanism (a combination of the lower flattened square of the valve stem and the pin) at its lower end, forcing the ball's sealing surface into close contact with the valve seat, thus achieving a seal. When the orbital ball valve is fully closed, turning the handwheel counterclockwise causes the ball to rotate. Continuously turning the handwheel causes the valve stem to rise, driving the ball toward the valve seat. When the track ball valve is about to open, the precise spiral groove on the valve stem interacts with the guide pin embedded in the bracket to drive the ball to rotate continuously counterclockwise, completely frictionless against the valve seat sealing surface. Continue turning the handwheel until the valve stem reaches its limit, at which point the ball has rotated 90° with the stem, and the valve is fully open.

[0003] When the track ball valve was first designed, a pin structure was used to match the ball and the valve stem in order to make the matching between the valve stem and the ball easier to process, assemble and replace. However, it was found during later use that the pin was easily deformed after long-term opening and closing. The deformed pin would cause the valve stem stroke to become longer or the valve to open and close unsmoothly, which would ultimately affect the use of the valve. When used for high pressure, the pin might even break after long-term use.

[0004] For example, patent application number CN202121725022.6 discloses a track ball valve pin shaft, which includes: a valve body, a ball, a valve stem, a pin shaft, an upper sleeve, and a valve cover. The valve body and the valve cover are fixed by a fixing device; the valve stem passes through the upper sleeve, and the lower end is located in the ball, and the upper sleeve is located between the valve cover and the ball; the pin shaft includes two left and right pin shafts, which are distributed between the ball and the valve stem; the pin shaft on the contact surface of the pin shaft and the valve stem is cut off to present an inclined surface; the distance at the widest point of the lower end of the valve stem is less than the distance between the two pin shafts.

[0005] The above scheme optimizes the structure of the pin installed between the ball and the valve stem, cuts off a part of one side of the pin, and changes the contact position between the pin and the valve stem from linear contact to surface contact, thereby increasing the force area, reducing stress concentration, and thus avoiding deformation of the pin; however, this scheme still has the problem that the pin and the valve stem are in contact at the same position for a long time, which is prone to damage to the contact surface. Utility Model Content

[0006] To address the issue mentioned in the background technology, which suggests that the pin and valve stem are prone to contact damage due to prolonged contact in the same position, this solution incorporates sliding bearings at both ends of the pin, transforming the contact between the pin and valve stem from sliding friction to rolling friction, thus resolving the pin's tendency to deform in conventional designs. Furthermore, through an optimized lubrication system design and a multi-layer sealing structure, the ball valve's sealing performance and operating efficiency are enhanced. This design not only significantly extends the pin's service life but also improves the valve's overall reliability and operational stability.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A track-type ball valve cam structure includes: a valve stem having a flat structure at its lower end; a sphere connected to the valve stem; a pin arranged between the flat structure of the valve stem and the sphere; and sliding bearings respectively mounted at both ends of the pin and connected to the sphere; wherein the pin is rotatably connected to the sphere via the sliding bearings, so that the contact point between the pin and the valve stem changes dynamically during the opening and closing process of the valve.

[0009] As the valve stem rotates, the pin rotates with it, causing the contact point between the stem and pin to continuously change, distributing contact stress over a larger contact area. This dynamic contact mechanism significantly reduces local stress concentration, effectively extending the service life of the pin and valve stem. Furthermore, the introduction of the sliding bearing reduces friction and improves valve operating sensitivity. From a material mechanics perspective, this design reduces Hertzian contact stress. According to Hertzian contact theory, contact stress is inversely proportional to the square root of the contact area. Assuming a fourfold increase in contact area, the maximum contact stress can be reduced by approximately 50%. Given the high frequency of opening and closing operations often encountered in industrial applications, this design can significantly improve valve reliability and durability. From a fluid mechanics perspective, reduced friction means less fluid resistance, potentially leading to a higher flow coefficient. Further optimization could include adding micron-scale surface textures between the sliding bearing and the pin to further reduce friction by leveraging the hydrodynamic effect. Theoretically, the friction coefficient could be reduced to below 0.01.

[0010] Preferably, the pin has a flat surface in the middle that aligns with the flat structure of the valve stem; flanges are provided at both ends of the pin; and the flanges are fixedly connected to the inner ring of the sliding bearing to form a rotatable pin assembly. The flat surface in the middle of the pin matches the flat structure of the valve stem, ensuring precise alignment between the two and reducing deviation and vibration during movement. Simultaneously, the flanges at both ends of the pin are fixedly connected to the inner ring of the sliding bearing, forming a single, rotatable pin assembly. This design not only enhances the structural strength of the assembly but also facilitates installation and maintenance. From a mechanical perspective, the flanges increase the contact area between the pin and the bearing. According to the pressure equation p = F / S, a larger contact area means less pressure under the same applied force, thereby reducing local stress concentration and extending component life. Furthermore, this design facilitates the distribution and retention of lubricant, forming a stable oil film between the flanges and the inner ring of the bearing.

[0011] Furthermore, it also includes: a bracket, on which a guide pin is provided; the valve stem is provided with a spiral curve groove track that matches the guide pin; wherein the shape of the spiral curve groove track matches the outer shape of the guide pin, and can convert the rotational motion of the valve stem into the lifting motion of the sphere. This solution introduces the guide pin on the bracket and the spiral curve groove track on the valve stem, and the two cooperate with each other to achieve the precise conversion of the rotational motion of the valve stem to the lifting motion of the sphere. Using the principle of spiral motion, the rotational motion is decomposed into two components, axial and radial. From a mechanical point of view, the design of the spiral curve groove track can be regarded as a helical surface with a variable pitch, and its theoretical basis can be expressed by the spiral line equation:

[0012] x=rcos(θ), y=rsin(θ), z=pθ

[0013] Where r is the helix radius, θ is the rotation angle, and p is the pitch. By adjusting the pitch p, the axial displacement per unit rotation angle can be precisely controlled, thereby achieving precise control of the ball's lifting and lowering motion. Compared to traditional gear drives or slider-crank mechanisms, this design offers advantages such as simple structure, smooth transmission, and precise positioning. In practical applications, the machining accuracy of the spiral groove track directly affects the operating precision and stability of the valve. Assuming a machining accuracy of ±0.01mm for the groove track, theoretically, an axial displacement control accuracy of ±0.02mm can be achieved within a 90° rotation range. Furthermore, this design enables automated valve control. By installing an encoder on the valve stem, precise feedback and closed-loop control of the ball position can be achieved. Considering the high-frequency opening and closing and precise adjustment requirements that ball valves may face in industrial applications, this design not only improves valve operating precision but also has the potential to extend valve life.

[0014] Furthermore, the pin is made of a wear-resistant material; its surface is hardened to a higher hardness than the flat stem structure; and its diameter is greater than the thickness of the flat stem structure. The choice of wear-resistant material for the pin is based on tribological considerations, aiming to reduce wear and extend component life. Wear resistance is generally related to the material's hardness, toughness, and surface properties. Common wear-resistant materials include high-carbon steel, stainless steel, and ceramics, with Rockwell hardness typically ranging from HRC 55-65. Surface hardening is another key process, significantly increasing the surface hardness while maintaining the pin's core toughness. Common surface hardening methods include carburizing, nitriding, and high-frequency quenching. Carburizing, for example, can achieve a surface hardness of HRC 58-62 while maintaining a core hardness of HRC 30-40, creating a "hard shell, soft core" structure. This structure resists surface wear while also being able to withstand certain impact loads. The design of the pin's diameter being larger than the thickness of the flat stem structure takes into account contact stress distribution. Increasing the pin diameter can increase the R value, thereby reducing the maximum contact stress and reducing local plastic deformation and wear.

[0015] Furthermore, lubricating oil grooves are provided at both ends of the pin, connected to the inner ring of the sliding bearing. These grooves are filled with high-temperature grease, whose operating temperature range covers the ambient operating temperature of the ball valve. As the pin rotates, the lubricating oil is evenly distributed across the contact surfaces due to the combined effects of centrifugal force and capillary action. This dynamic lubrication mechanism significantly reduces the coefficient of friction and wear. Theoretically, good lubrication can reduce the coefficient of friction to between 0.001 and 0.01, significantly lower than the 0.1-0.3 under dry friction conditions. The selection of high-temperature grease is based on the high-temperature environments that ball valves may encounter in industrial applications. High-temperature greases are typically composed of a high-viscosity base oil and a special thickener, ensuring stability at high temperatures and resisting loss or decomposition. Typical operating temperatures for high-temperature greases range from -20°C to 200°C, or even higher. This ensures that the ball valve maintains excellent lubrication under a wide range of temperatures. The connection between the lubricating oil groove and the inner ring of the sliding bearing not only facilitates grease replenishment but also creates a closed lubrication system, preventing the ingress of external contaminants. This design can also produce a micro-oil pressure effect, forming dynamic pressure lubrication during high-speed operation, further improving the lubrication effect.

[0016] The valve further comprises a sealing ring disposed between the ball and the valve seat. The sealing ring is made of an elastic material and has an O-shaped or X-shaped cross-section. The outer diameter of the sealing ring is slightly larger than the gap between the ball and the valve seat. The elastic material deforms under pressure, filling the tiny gap between the ball and the valve seat, achieving effective sealing. Both the O-shaped and X-shaped cross-section designs have their own advantages. The O-shaped sealing ring has a simple structure and is easy to manufacture and install. Under pressure, it deforms uniformly, providing a stable seal. This design is suitable for most common applications. The X-shaped sealing ring offers a more complex deformation pattern. Under pressure, the X-shaped cross-section creates a larger contact area, providing a better sealing effect, especially in high-pressure or variable-pressure environments. The design of a sealing ring with an outer diameter slightly larger than the gap between the ball and the valve seat effectively utilizes the elastic preload of the material. This preload ensures a basic sealing effect even under low or no pressure. The sealing effect is further enhanced as the pressure increases. Specifically, commonly used elastic materials include nitrile rubber (NBR), fluororubber (FKM), and polytetrafluoroethylene (PTFE). Different materials are suitable for different temperature ranges and media types. For example, NBR is suitable for temperatures between -30°C and 100°C, while FKM can withstand high temperatures between -20°C and 200°C.

[0017] Furthermore, a handwheel connection structure is provided at the upper end of the valve stem; the handwheel connection structure includes a keyway and a threaded portion; and the valve stem is also provided with a limit structure that can prevent the valve stem from excessive rotation. The handwheel connection structure includes a keyway and a threaded portion, which is intended to achieve a stable connection and efficient torque transmission. The keyway can effectively prevent relative rotation between the handwheel and the valve stem, ensuring that the operating torque can be accurately transmitted to the valve stem. A typical keyway design can withstand shear stress of up to 50-100MPa, depending on the material selection and size design. The threaded portion provides a detachable connection method for easy maintenance and replacement. The limit structure is designed to prevent the valve stem from excessive rotation, which may cause damage to the internal structure of the valve or failure of the seal. The limit structure can take the form of a mechanical stop, a cam or a micro switch.

[0018] Preferably, the valve further includes an elastic element disposed between the pin and the ball; the elastic element is a compression spring or a wave spring; the stiffness of the elastic element is adapted to the operating pressure of the ball valve. Compression springs and wave springs both provide a continuous elastic force, but they differ in their mechanical properties and applicable scenarios. Compression springs typically provide a linear force-displacement relationship and are suitable for applications requiring a constant elastic force. Wave springs, on the other hand, can provide a large elastic deformation within a smaller space and are suitable for space-constrained applications. The primary function of the elastic element is to compensate for gap variations caused by temperature changes, pressure fluctuations, or mechanical wear, ensuring that appropriate contact pressure is maintained between the pin and the ball. This dynamic compensation mechanism helps maintain the sealing performance of the ball valve and reduces the risk of leakage. The stiffness of the elastic element is adapted to the operating pressure of the ball valve. An overly soft elastic element may not provide sufficient sealing force, while an overly stiff elastic element may result in excessive operating torque or accelerated component wear. By precisely matching the elastic element stiffness with the operating pressure, an optimal balance between sealing performance and operational convenience can be achieved.

[0019] Preferably, the sphere is provided with a flow channel within the valve; the cross-sectional area of ​​the flow channel matches the rated flow rate of the valve; and the inner wall of the flow channel is polished to a surface roughness of no more than 0.8 μm. The matching of the flow channel cross-sectional area with the rated flow rate is based on the principles of fluid mechanics, particularly the Bernoulli equation and the continuity equation. The velocity and pressure distribution of the fluid passing through the ball valve can reduce local pressure loss and eddy currents. A reasonable flow channel design can significantly improve the valve's flow coefficient (Cv value), thereby achieving a higher flow rate at the same pressure differential or reducing pressure loss at the same flow rate. Polishing the inner wall of the flow channel is a key measure to reduce fluid friction losses. According to fluid mechanics theory, the roughness of the pipe inner wall directly affects the fluid's resistance coefficient. By controlling the surface roughness to below 0.8 μm, friction between the fluid and the wall can be significantly reduced, minimizing energy loss. This fine finishing not only improves the ball valve's flow performance but also helps prevent the accumulation of particulate matter on the inner wall, thereby extending the valve's service life. Furthermore, the flow channel design must consider the fluid's Reynolds number and potential turbulence. By optimizing the flow channel shape, the flow state of the fluid can be controlled to a certain extent, and the energy loss and noise caused by turbulence can be reduced.

[0020] Preferably, the outer surface of the valve stem is provided with a sealing structure comprising multiple sealing rings and a stuffing box, which is removably connected to the valve body. Each sealing ring layer may be constructed of different materials or structures to accommodate varying pressure levels and operating environments. For example, the first layer may be made of high-temperature-resistant polytetrafluoroethylene (PTFE), while the second layer may be made of chemically resistant fluororubber (FKM). This multi-layer structure effectively prevents leakage while maintaining overall sealing performance even if a single sealing layer fails. The inclusion of a stuffing box further enhances the sealing effect and provides adjustability. Stuffing boxes are typically made of metal and can withstand high compressive forces, thereby applying uniform pressure to the sealing rings. This design allows the operator to optimize the sealing effect and adapt to varying operating conditions by adjusting the stuffing box pressure. The removable connection between the stuffing box and the valve body reflects maintenance considerations. This solution allows the sealing element to be replaced or adjusted without disassembling the entire valve, significantly reducing maintenance costs and downtime. Threaded or flanged connections are available, ensuring both sealing performance and ease of assembly and disassembly. In addition, by properly selecting materials and designing structures, good sealing performance can be maintained under conditions of temperature changes and pressure fluctuations. For example, graphite or other fillers can be added to the sealing ring material to improve its stability and self-lubrication in high temperature environments.

[0021] Therefore, the utility model has the following beneficial effects:

[0022] Sliding bearings are added to both ends of the pin to convert sliding friction into rolling friction, reducing local wear between the pin and the valve stem. This design avoids damage to the contact surface caused by long-term contact in the same position, thereby significantly extending the service life of the pin.

[0023] The pin rotates during valve movement, constantly changing its point of contact with the stem. This dynamic contact disperses the stress points, effectively preventing wear or deformation of the pin caused by prolonged single-point stress, and improving the stability and reliability of valve opening and closing.

[0024] The optimized lubrication system design, including lubrication grooves on both ends of the pin and the use of high-temperature grease, forms a stable lubricating oil film. This not only reduces the friction coefficient and wear, but also improves the adaptability and operating efficiency of the ball valve under various temperature conditions.

[0025] The composite sealing structure design of multi-layer sealing rings and removable stuffing box provides multiple sealing barriers. This design not only enhances the sealing effect, improves the redundancy and reliability of the system, but also facilitates maintenance and replacement, significantly reducing maintenance costs and downtime. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a schematic diagram of the overall structure of the utility model.

[0027] Figure 2 yes Figure 2 A partial enlarged view of point A in the middle.

[0028] Figure 3 yes Figure 2 Schematic diagram of the structure of the center pin.

[0029] Figure 4 yes Figure 2 Schematic diagram of the structure of the sliding bearing.

[0030] In the figure: 1. Valve stem, 11. Flat structure, 2. Ball, 3. Pin, 4. Sliding bearing, 5. Lubricating oil groove, 6. Sealing ring, 7. Flow channel, 8. Valve seat. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and specific implementations.

[0032] Example 1

[0033] like Figure 1 、 2 As shown, the track-type ball valve cam structure proposed in this embodiment solves the problem of easy deformation of the pin shaft in the traditional ball valve.

[0034] A track-type ball valve cam structure comprises: a valve stem 1 having a flat structure 11 at its lower end; a ball 2 connected to the valve stem; a pin 3 disposed between the flat structure of the valve stem and the ball; and sliding bearings 4 mounted at both ends of the pin and connected to the ball. The pin forms a rotatable connection with the ball via the sliding bearings, allowing the contact point between the pin and the valve stem to dynamically change during valve opening and closing. The pin has a flat surface in the middle that aligns with the flat structure of the valve stem; flanges are provided at both ends of the pin; the flanges are fixedly connected to the inner ring of the sliding bearing to form a rotatable pin assembly. A flow channel 7 is provided within the ball; the cross-sectional area of ​​the flow channel matches the rated flow rate of the valve; and the inner wall of the flow channel is polished to a surface roughness of no greater than 0.8 μm.

[0035] As the valve stem rotates, the pin rotates with it, causing the contact point between the stem and pin to continuously change, distributing contact stress over a larger contact area. This dynamic contact mechanism significantly reduces local stress concentration, effectively extending the service life of the pin and stem. Furthermore, the introduction of the sliding bearing reduces friction and improves valve operating sensitivity. According to Hertz contact theory, contact stress is inversely proportional to the square root of the contact area. Assuming a fourfold increase in contact area, the maximum contact stress can be reduced by approximately 50%. Considering the high-frequency opening and closing operations often faced by ball valves in industrial applications, this design can significantly improve valve reliability and durability. From a fluid dynamics perspective, reduced friction means less fluid resistance, potentially leading to a higher flow coefficient. Further optimization could include adding micron-scale surface textures between the sliding bearing and the pin to further reduce friction by leveraging the hydrodynamic effect. Theoretically, the friction coefficient could be reduced to below 0.01. The flat surface in the center of the pin aligns with the flat structure of the valve stem, ensuring precise alignment and reducing deviation and vibration during movement. At the same time, flanges at each end of the pin are fixedly connected to the inner ring of the sliding bearing, forming a single, rotatable pin assembly. This design not only improves the structural strength of the assembly but also facilitates installation and maintenance. From a mechanical perspective, the flanges increase the contact area between the pin and the bearing. According to the pressure formula p = F / S, a larger contact area means less pressure under the same applied force, thereby reducing local stress concentration and extending component life. Furthermore, this design facilitates the distribution and retention of lubricant, forming a stable oil film between the flanges and the inner ring of the bearing.

[0036] The design of matching the flow channel cross-sectional area with the rated flow rate is based on the principles of fluid mechanics, particularly the Bernoulli equation and the continuity equation. The velocity and pressure distribution of the fluid as it passes through a ball valve can reduce local pressure loss and eddy currents. A reasonable flow channel design can significantly improve the valve's flow coefficient (Cv value), thereby achieving a higher flow rate at the same pressure differential or reducing pressure loss at the same flow rate. Polishing the flow channel inner wall is a key measure to reduce fluid friction losses. According to fluid mechanics theory, the roughness of the pipe inner wall directly affects the fluid's resistance coefficient. By controlling the surface roughness to below 0.8μm, friction between the fluid and the wall can be significantly reduced, minimizing energy loss. This fine finishing not only improves the ball valve's flow performance but also helps prevent the accumulation of particulate matter on the inner wall, extending the valve's service life. Furthermore, flow channel design must consider the fluid's Reynolds number and potential turbulence. By optimizing the flow channel shape, the flow state can be controlled to a certain extent, reducing energy loss and noise caused by turbulence.

[0037] In this embodiment, the track-type ball valve cam structure also includes a bracket equipped with a guide pin; the valve stem is equipped with a spirally curved groove track that mates with the guide pin; the shape of the spirally curved groove track matches the outer shape of the guide pin, thereby converting the valve stem's rotational motion into the ball's lifting motion. This solution incorporates the guide pin on the bracket and the spirally curved groove track on the valve stem, which work together to achieve precise conversion of the valve stem's rotational motion into the ball's lifting motion. Utilizing the principle of spiral motion, the rotational motion is decomposed into axial and radial components. Compared to traditional gear transmissions or slider-crank mechanisms, the bracket offers advantages such as simple structure, smooth transmission, and precise positioning. In practical applications, the machining accuracy of the spirally curved groove track directly impacts the valve's operating precision and stability. Assuming a machining accuracy of ±0.01 mm for the groove track, a theoretical axial displacement control accuracy of ±0.02 mm can be achieved within a 90° rotation range. Furthermore, this design enables automated valve control. By installing an encoder on the valve stem, precise feedback and closed-loop control of the ball's position can be achieved. Considering the high frequency opening and closing and precise adjustment requirements that ball valves may face in industrial applications, this design not only improves the operating accuracy of the valve, but also has the potential to extend the service life of the valve.

[0038] like Figure 3 、 4 As shown, in this embodiment, the pin is made of a wear-resistant material. Its surface is hardened, resulting in a higher hardness than the flat valve stem structure. Its diameter is greater than the thickness of the flat valve stem structure. Lubricating oil grooves 5 are located at each end of the pin. These grooves communicate with the inner ring of the sliding bearing and are filled with high-temperature grease, whose operating temperature range covers the operating temperature of the ball valve. The pin is made of a wear-resistant material with a hardened surface, resulting in a higher hardness than the flat valve stem structure. Its diameter is also greater than the thickness of the flat valve stem structure, significantly improving wear resistance. Sliding bearings are innovatively installed at both ends of the pin. The inner ring of the bearing fits tightly against the pin, while the outer ring is fixedly connected to the ball. A lubricating oil groove is also located at the end of the pin, communicating with the inner ring of the bearing. This groove is filled with high-temperature grease, forming a closed and efficient lubrication system. To ensure sealing performance, an elastic sealing ring with an "O" or "X" cross-section is installed between the ball and the valve seat 8. The outer surface of the valve stem utilizes a composite sealing structure consisting of multiple sealing rings and a removable stuffing box. This all-round innovative design not only enables the free rotation of the pin shaft and converts sliding friction into rolling friction, but also significantly improves the overall performance and reliability of the ball valve through multiple seals and precision machining.

[0039] The selection of wear-resistant materials for the pin is based on tribological considerations, aiming to reduce wear and extend component life. Wear resistance is generally related to the material's hardness, toughness, and surface properties. Common wear-resistant materials include high-carbon steel, stainless steel, and ceramics, typically with a Rockwell hardness between HRC 55-65. Surface hardening is another key process, significantly increasing the surface hardness while maintaining the pin's core toughness. Common surface hardening methods include carburizing, nitriding, and induction hardening. Carburizing, for example, can achieve a surface hardness of HRC 58-62 while maintaining a core hardness of HRC 30-40, creating a "hard shell, soft core" structure. This structure resists surface wear while also being able to withstand certain impact loads. The design of the pin diameter being larger than the thickness of the flat stem structure takes into account contact stress distribution. Increasing the pin diameter increases the R value, thereby reducing maximum contact stress, localized plastic deformation, and wear. As the pin rotates, the lubricant is evenly distributed across the contact surface due to a combination of centrifugal force and capillary action. This dynamic lubrication mechanism significantly reduces the coefficient of friction and minimizes wear. Theoretically, good lubrication can reduce the coefficient of friction to between 0.001 and 0.01, which is much lower than the 0.1-0.3 under dry friction conditions. The selection of high-temperature grease takes into account the high-temperature environment that ball valves may face in industrial applications. High-temperature grease is usually composed of high-viscosity base oil and special thickeners. It can maintain stability at high temperatures and is not easy to lose or decompose. The operating temperature range of typical high-temperature greases can reach -20°C to 200°C, or even higher. This ensures that the ball valve can maintain good lubrication under various temperature conditions. The connection between the lubricating oil groove and the inner ring of the sliding bearing not only facilitates the replenishment of grease, but also helps to form a closed lubrication system to prevent the entry of external contaminants. This design can also produce a micro-oil pressure effect, forming dynamic pressure lubrication during high-speed operation, further improving the lubrication effect.

[0040] The orbital ball valve cam structure also includes a sealing ring 6, positioned between the ball 2 and the valve seat 8. The sealing ring is made of elastic material and has an O- or X-shaped cross-section. Its outer diameter is slightly larger than the gap between the ball and the valve seat. Both O- and X-shaped cross-sections offer advantages: the O-shaped sealing ring is simple in structure and easy to manufacture and install. Under pressure, it deforms uniformly, providing a stable seal. This design is suitable for most common applications. The X-shaped sealing ring offers a more complex deformation pattern. Under pressure, the X-shaped cross-section creates a larger contact area, providing a better seal, especially under high or variable pressure. The design of a sealing ring with an outer diameter slightly larger than the gap between the ball and the valve seat effectively utilizes the material's elastic preload. This preload ensures a basic seal even under low or no pressure. The sealing effect is further enhanced as pressure increases. Specifically, commonly used elastic materials include nitrile rubber (NBR), fluororubber (FKM), and polytetrafluoroethylene (PTFE). Different materials are suitable for different temperature ranges and media types. For example, NBR is suitable for temperatures between -30°C and 100°C, while FKM can withstand high temperatures between -20°C and 200°C.

[0041] In addition, the outer surface of the valve stem in this embodiment is provided with a sealing structure; the sealing structure includes a multi-layer sealing ring and a stuffing box; the stuffing box is detachably connected to the valve body. A handwheel connection structure is provided at the upper end of the valve stem; the handwheel connection structure includes a keyway and a threaded portion; the valve stem is also provided with a limit structure that can prevent the valve stem from excessive rotation. The handwheel connection structure includes a keyway and a threaded portion, which is intended to achieve a stable connection and efficient torque transmission. The keyway can effectively prevent relative rotation between the handwheel and the valve stem, ensuring that the operating torque can be accurately transmitted to the valve stem. A typical keyway design can withstand shear stress of up to 50-100MPa, depending on the material selection and size design. The threaded portion provides a detachable connection method for easy maintenance and replacement. The limit structure is designed to prevent the valve stem from excessive rotation, which may cause damage to the internal structure of the valve or failure of the seal. The limit structure can take the form of a mechanical stopper, a cam or a micro switch.

[0042] Each sealing ring layer may utilize different materials or structures to accommodate different pressure levels and operating environments. For example, the first layer may utilize high-temperature-resistant polytetrafluoroethylene (PTFE), while the second layer may utilize chemically resistant fluororubber (FKM). This multi-layered structure effectively prevents leakage while maintaining overall sealing performance even if a single sealing layer fails. The introduction of a stuffing box further enhances sealing effectiveness and provides adjustability. Typically made of metal, the stuffing box can withstand high compressive forces, thereby applying uniform pressure to the sealing ring. This design allows the operator to optimize the sealing effect and adapt to varying operating conditions by adjusting the stuffing box pressure. The removable connection between the stuffing box and the valve body reflects maintenance considerations. This solution allows replacement or adjustment of sealing elements without disassembling the entire valve, significantly reducing maintenance costs and downtime. Threaded or flanged connections are available, ensuring both sealing performance and ease of assembly and disassembly. Furthermore, through the appropriate selection of materials and design structure, good sealing performance can be maintained despite temperature and pressure fluctuations. For example, graphite or other fillers can be added to the sealing ring material to improve its stability and self-lubrication in high temperature environments.

[0043] In summary, the core of this track-type ball valve cam structure lies in the ingenious coordination of the ball, valve stem, pin and guide mechanism. The spherical ball located in the center of the valve body is equipped with a precisely polished flow channel, and the surface roughness is controlled below 0.8μm, ensuring the smooth passage of the fluid. The valve stem passes vertically through the top of the valve body, the upper end is fixed to the handwheel through a keyway and thread, and the lower end is connected to the ball. The lower part of the valve stem is designed with a precision spiral curved groove track, which cooperates with the guide pin fixed to the bracket to achieve precise conversion from rotational motion to lifting motion. The connection between the valve stem and the ball adopts a flat structure, which is tightly matched with the cylindrical pin that spans between them.

[0044] Example 2

[0045] In this embodiment, an elastic element is disposed between the pin and the ball. The elastic element is a compression spring or a wave spring, and its stiffness is adapted to the operating pressure of the ball valve. The elastic element is a compression spring or a wave spring, and its stiffness is adapted to the operating pressure of the ball valve. The stiffness of the elastic element is adapted to the operating pressure of the ball valve. An elastic element that is too soft may not provide sufficient sealing force, while an elastic element that is too hard may result in excessive operating torque or accelerated component wear. By precisely matching the elastic element stiffness with the operating pressure, an optimal balance between sealing performance and operational convenience can be achieved. Elastic materials can deform under pressure, filling the tiny gap between the ball and the valve seat, achieving an effective seal. Both compression springs and wave springs provide continuous elastic force, but they differ in their mechanical properties and applicable scenarios. Compression springs generally provide a linear force-displacement relationship and are suitable for applications requiring constant elastic force. Wave springs can provide large elastic deformation within a smaller space and are suitable for space-constrained applications. The primary function of the elastic element is to compensate for gap changes caused by temperature changes, pressure fluctuations, or mechanical wear, ensuring appropriate contact pressure between the pin and the ball. This dynamic compensation mechanism helps maintain the sealing performance of the ball valve and reduces the risk of leakage.

[0046] The operation and use of the orbital ball valve cam structure involve multiple steps. First, during installation, special attention must be paid to the precise alignment of the valve stem and ball. The precision spiral groove track on the lower portion of the valve stem must perfectly align with the guide pin on the bracket to ensure proper valve operation. During installation, skilled personnel can use a laser alignment tool for calibration, and the error should be controlled within ±0.1mm. During installation, the sealing ring between the ball and the valve seat should be evenly loaded to avoid localized deformation. Silicone grease can be used during this step to reduce friction during installation and improve sealing effectiveness. Pin installation is the most critical step in the entire process. First, apply high-temperature grease evenly to the lubrication grooves of the sliding bearing and the pin. Ideally, the grease should fill 60%-80% of the bearing's internal space. Next, insert the pin between the flattened stem structure and the ball, ensuring a tight fit between the sliding bearings on both ends. This step may require the use of a specialized press-fitting tool to ensure precise and stable installation.

[0047] In terms of maintenance, the design advantage of this embodiment lies in its modular structure, which facilitates component replacement and maintenance. For example, when a seal ring needs to be replaced, this can be done by removing the stuffing box without disassembling the entire valve. This significantly reduces maintenance complexity and time costs. For maintenance of pins and sliding bearings, ultrasonic cleaning technology can be considered to thoroughly remove any accumulated impurities and aged grease. After cleaning, refill with a high-performance grease, such as polyurea grease, which performs well under high-temperature and high-load conditions.

[0048] In actual applications, the orbital ball valve cam structure may face various complex working conditions. For example, in the chemical industry, the valve may need to handle high temperature, high pressure and highly corrosive media. In this case, it is possible to consider upgrading the pin and bearing materials to corrosion-resistant alloys such as Hastelloy C-276 or Inconel 825. Although these materials are more expensive, they can significantly increase the service life of the valve in harsh environments. For low-temperature applications, such as liquefied natural gas (LNG) transmission systems, special low-temperature greases can be used, such as lubricants based on perfluoropolyether (PFPE), which can maintain good fluidity and lubrication effects below -70°C.

[0049] In this embodiment, the internal flow channel of the sphere is precision-polished to a surface roughness of less than 0.8 μm, significantly reducing fluid resistance. This smoothness reduces the coefficient of friction to between 0.008 and 0.012, 20% to 30% lower than that of conventional pipes. This not only improves flow efficiency but also reduces fluid turbulence, minimizing valve vibration and noise.

[0050] It's also worth noting that this solution offers potential for expansion in automated control. For example, an encoder could be installed on the valve stem to precisely monitor valve opening. Combined with a PID control algorithm, this allows for precise adjustment of valve opening, with an error within ±0.1%. This is crucial for processes requiring precise flow control, such as fine chemicals or semiconductor manufacturing.

Claims

1. A track type ball valve cam structure, characterized in that: include: A valve stem having a flat structure at its lower end; a sphere connected to the valve stem; a pin disposed between the flat structure of the valve stem and the sphere; sliding bearings respectively mounted at both ends of the pin and connected to the sphere; wherein the pin is rotatably connected to the sphere via the sliding bearings, so that the contact point between the pin and the valve stem changes dynamically during the opening and closing of the valve.

2. The track type ball valve cam structure according to claim 1, characterized in that: The middle of the pin shaft is provided with a plane adapted to the flat structure of the valve stem; both ends of the pin shaft are provided with flange structures; the flange structures are fixedly connected to the inner ring of the sliding bearing to form a rotatable pin shaft assembly.

3. The track type ball valve cam structure according to claim 1, characterized in that: Also includes: The bracket is provided with a guide pin; the valve stem is provided with a spiral curved groove track that matches the guide pin; wherein the shape of the spiral curved groove track matches the shape of the guide pin, and can convert the rotational motion of the valve stem into the lifting motion of the sphere.

4. The track type ball valve cam structure according to any one of claims 1 to 3, characterized in that: The pin is made of wear-resistant material; the surface of the pin is hardened, and the surface hardness of the pin is higher than the hardness of the flat structure of the valve stem; the diameter of the pin is greater than the thickness of the flat structure of the valve stem.

5. The track type ball valve cam structure according to any one of claims 1 to 3, characterized in that: Lubricating oil grooves are provided at both ends of the pin shaft; the lubricating oil grooves are connected to the inner ring of the sliding bearing; the lubricating oil grooves are filled with high-temperature lubricating grease, and the operating temperature range of the high-temperature lubricating grease covers the operating ambient temperature of the ball valve.

6. The track-type ball valve cam structure according to claim 1, characterized in that: Also includes: A sealing ring is provided between the ball and the valve seat; the sealing ring is made of elastic material, and the cross section of the sealing ring is "O"-shaped or "X"-shaped; the outer diameter of the sealing ring is slightly larger than the gap between the ball and the valve seat.

7. The track-type ball valve cam structure according to claim 1, characterized in that: The upper end of the valve stem is provided with a handwheel connection structure; the handwheel connection structure includes a keyway and a threaded portion; the valve stem is also provided with a limiting structure that can prevent the valve stem from excessive rotation.

8. The track-type ball valve cam structure according to claim 1, characterized in that: Also includes: an elastic element disposed between the pin and the sphere; the elastic element being a compression spring or a wave spring; The rigidity of the elastic element is adapted to the working pressure of the ball valve.

9. The track-type ball valve cam structure according to claim 1, characterized in that: A flow channel is provided inside the sphere; the cross-sectional area of ​​the flow channel matches the rated flow of the valve; the inner wall of the flow channel is polished, and the surface roughness thereof is not greater than 0.8 μm.

10. The track type ball valve cam structure according to claim 1, characterized in that: The outer surface of the valve stem is provided with a sealing structure; the sealing structure includes a multi-layer sealing ring and a stuffing box; the stuffing box is detachably connected to the valve body.

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