Interference-Free Butterfly Valve for Piping Systems

Abstract

The present invention relates to a butterfly valve for opening and closing a fluid flow or controlling the flow rate, and more specifically, to a pipe interference prevention type butterfly valve having a pipe interference prevention structure capable of preventing physical collision with the inner diameter surface of a pipe when the valve disc rotates to open and close. In particular, the present invention relates to the field of butterfly valve technology, which can maintain low driving torque and high airtightness by securing clearance with the pipe and inducing line contact with the seat through a curvature-buffering VR processing structure formed at the outer diameter end of the disc, even when installed in synthetic resin pipes or lined pipes that are prone to deformation due to thermal expansion or external pressure. The present invention was developed to solve the various problems of the prior art as described above. The main technical problem that the present invention aims to solve is to provide a butterfly valve that can reduce operating torque and significantly improve the durability of the seat by minimizing the contact area with the seat during valve opening and closing operation by forming the edge of the valve disc into a VR processing structure which is a curvature cushioning structure.

Description

Technology Field

[0001] The present invention relates to a butterfly valve for opening and closing a fluid flow or controlling the flow rate, and more specifically, to a pipe interference prevention type butterfly valve having a pipe interference prevention structure capable of preventing physical collision with the inner diameter surface of a pipe when the valve disc rotates to open and close.

[0002] In particular, the present invention relates to the field of butterfly valve technology, which can maintain low driving torque and high airtightness by securing clearance with the pipe and inducing line contact with the seat through a curvature-buffering VR processing structure formed at the outer diameter end of the disc, even when installed in synthetic resin pipes or lined pipes that are prone to deformation due to thermal expansion or external pressure. Background Technology

[0003] A butterfly valve is a device that opens and closes the flow of fluid or regulates the flow rate by placing a disc-shaped plate that rotates around a central axis inside the valve body.

[0004] Compared to other types of valves (e.g., gate valves, globe valves, etc.), these butterfly valves possess unique advantages, such as a simple structure and light weight that facilitate installation and maintenance even in large-diameter piping, and a short face-to-face distance that enables efficient piping design even in confined spaces.

[0005] Accordingly, it is widely adopted and operated as a core control device in various fields, such as water treatment facilities, power plants, petrochemical plants, and various industrial fluid transfer pipelines. In particular, to maximize airtightness performance, an elastic seat made of rubber or synthetic resin is lined or mounted on the inner side of the valve body, and the structure is based on a design in which fluid leakage is blocked by the edge of the disc compressing the seat when the disc rotates 90 degrees to reach the closed position.

[0006] In conventional butterfly valves, the so-called 'V-Cut' method, which involves machining the disc edge into a sharp wedge shape or a V-shape with a sharp angle, has been primarily applied. While this machining method theoretically aims for line contact with the seat, it exposes the following serious technical problems in actual operating environments.

[0007] First, when the sharp V-shaped edge comes into contact with the elastic seat, excessive localized stress concentration occurs. This induces a "pinching" phenomenon, where the edge physically presses down on or digs into the seat surface. Consequently, the sharp edge becomes embedded within the seat, forming an irregular and wide area of ​​"surface contact." This surface contact dramatically increases frictional resistance between the disc and the seat, becoming the primary cause of the sharp increase in the torque required for valve operation.

[0008] Second, such excessive compression and friction cause premature wear and permanent deformation of the seat during the repeated opening and closing process. Irreversible damage to the seat reduces long-term airtightness, leading to fluid leakage accidents, and results in economic losses by increasing maintenance costs in industrial sites by shortening the overall replacement cycle of the valve.

[0009] Recently, the use of non-metallic pipes made of synthetic resins such as polyethylene (PE) and polypropylene (PP), or pipes lined with special resins, has been rapidly increasing in the industrial sector to ensure corrosion resistance, reduce weight, and maximize construction efficiency. However, compared to steel pipes, these non-metallic pipes possess physical weaknesses, such as lower rigidity and a very high coefficient of thermal expansion.

[0010] In particular, a phenomenon called "elliptical deformation" is frequently reported, in which the inner diameter of the pipe shrinks or its circularity collapses, distorting into an elliptical shape, due to external pressures such as soil loads or vibrations, or changes in the temperature of the conveyed fluid. Such deformation of the pipe shape poses a critical threat to the operational reliability of butterfly valves.

[0011] Specifically, in the 'Full Open' state where the valve disc stands parallel to the flow path, if the clearance between the inwardly protruding pipe wall and the outer diameter end of the disc is insufficient, a physical jamming phenomenon occurs.

[0012] In other words, 'pipe interference' occurs. Once the disc gets stuck against the inner wall of the pipe, the valve becomes unable to open or close, which poses a potential risk factor that could cause serious safety accidents, such as large-scale flooding or explosions, due to the failure to block the flow path in an emergency.

[0013] If the valve is attempted to be operated forcefully in the aforementioned pipe interference situation or under conditions where the frictional resistance of the seat is extreme, massive torsional stress is applied to the stem that transmits rotational force.

[0014] Stainless steel materials (e.g., STS304, STS316, etc.) commonly used in conventional butterfly valves have excellent corrosion resistance but have the limitation of relatively low yield strength. Consequently, when an excessive load exceeding the design torque is applied, plastic deformation occurs where the stem permanently twists in the rotational direction, or in severe cases, failure such as breakage frequently occurs.

[0015] This goes beyond a mere valve failure, causing a shutdown of the entire process and entailing massive equipment repair costs due to complex replacement work.

[0016] Therefore, there is a strong demand for the development of an innovative butterfly valve featuring an organic combination of high-strength materials and structures that can maintain stem integrity even under high-load conditions, along with a geometric design capable of securing sufficient clearance between the disc and the piping even under minute deformations, and improving contact characteristics with the seat to minimize driving load. Prior art literature

[0017] Korean Patent Publication No. 10-1203680 The problem to be solved

[0018] The present invention was developed to solve the various problems of the prior art as described above. The main technical problem that the present invention aims to solve is to provide a butterfly valve that can reduce operating torque and significantly improve the durability of the seat by minimizing the contact area with the seat during valve opening and closing operation by forming the edge of the valve disc into a VR processing structure which is a curvature cushioning structure.

[0019] Another objective of the present invention is to provide a butterfly valve capable of fundamentally preventing physical interference and jamming between the disc and the pipe, even in non-metallic piping environments where shrinkage or elliptical deformation is prone to occur due to thermal deformation or external pressure, by designing the radial clearance between the outer end of the disc and the inner surface of the pipe when the valve is in a fully open state.

[0020] Another objective of the present invention is to provide a butterfly valve that can achieve stable sealing performance with low operating force by forming the inner diameter surface of the seat into a diagonal structure that gradually tapers toward the center and organically combining it with a VR-machined disc, thereby securing the sealing force for maintaining airtightness while inducing the actual contact section to be close to precise linear contact.

[0021] Another objective of the present invention is to prevent torsional deformation and breakage of the stem even in situations involving pipe deformation or abnormally high torque, and to ensure long-term operational reliability of the valve, by applying a stem made of a high-strength material with a controlled specific alloy composition ratio to withstand structural loads resulting from the design of miniaturization of the disc and securing clearance.

[0022] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0023] According to one embodiment of the present invention, a butterfly valve installed in a pipe to control the flow of fluid comprises: a valve body having a fluid passage formed in the center; a disc rotatably installed within the fluid passage of the valve body; a seat disposed between the valve body and the disc to maintain airtightness; and a stem connected to the disc to transmit rotational force. The disc is formed with a VR machining structure having a predetermined curvature (R) at the edge, and a radial clearance defined as the shortest distance between the inner diameter surface of the pipe and the edge of the disc. By the VR machining structure, the radial clearance is formed to be greater than the thickness of the seat when the disc is fully open. The seat has both sides of the inner diameter surface that gradually taper toward the center to minimize the surface contact area when in contact with the VR machining surface formed with a curvature-buffering shape of the VR machining structure.

[0024] The curvature (R) of the above VR processing structure is formed to have a range of 0.5T to 1.5T relative to the maximum thickness (T) of the disk, and the outer diameter (D) of the disk is formed to have a diameter reduced by 5% to 12% relative to the effective inner diameter (A) of the stub end, and the radial clearance (C) is formed by the difference between the inner diameter (A) of the stub end and the outer diameter (D) of the disk, and is formed to a size of 1.2 to 2.0 times the thickness of the sheet, thereby maintaining airtightness through elastic compression of the sheet even in the case of elliptical deformation of the pipe, and at the same time ensuring an interference-free rotational trajectory of the disk.

[0025] The above VR processing structure is variably designed to correspond to changes in the inner diameter (A) of the stub end according to the material of the pipe, and the clearance when applying a flexible PE pipe ( ) and clearance when applying rigid PVC piping ( The ratio of ) The outer diameter (D) and curvature (R) of the disk are adjusted so that the range of 0.8 to 1.2 is maintained, thereby ensuring the same level of operational safety margin even in piping environments with different strain and inner diameter dimensions.

[0026] The above stem is made of precipitation-hardened stainless steel and contains, in weight percent, chromium (Cr): 15.0 ~ 17.5%, nickel (Ni): 3.0 ~ 5.0%, copper (Cu): 3.0 ~ 5.0%, and the remainder consists of iron (Fe) and other unavoidable impurities, thereby suppressing torsional deformation of the stem even under eccentric load caused by deformation of the pipe.

[0027] On the upper part of the stem, a stem seal, a stem bushing, a split ring, a thrust washer, and a retaining ring are sequentially stacked and combined from the lower part to the upper part, and a stem bearing that supports the rotational drive of the stem is provided at the upper part and the lower part of the stem, respectively, and a lower support housing that accommodates the lower end of the stem and the stem bearing is integrally formed at the lowest part of the valve body to support the stem at both ends. Effects of the invention

[0028] According to the present invention, by forming a VR processing structure with a curvature buffer shape on the edge of the disc, the contact area with the seat during the opening and closing operation of the valve can be minimized, thereby drastically reducing the operating torque. This not only reduces the load on the driving device and increases the overall energy efficiency of the system, but also prevents local stress concentration on the seat, thereby suppressing wear on the seat and extending its lifespan.

[0029] In addition, according to the present invention, by securing a radial clearance greater than the thickness of the seat, which is the shortest distance between the outer end of the disc and the inner surface of the pipe when the valve is fully open, physical interference and jamming between the disc and the pipe can be fundamentally prevented even in non-metallic piping environments where deformation is likely to occur due to thermal expansion or external pressure, thereby preventing valve sticking accidents and maximizing operational safety even during pipe contraction or elliptical deformation.

[0030] In addition, according to the present invention, by applying a stem made of a high-strength precipitation-hardened stainless steel material with a precisely controlled specific alloy composition ratio, torsional deformation or breakage of the stem can be prevented even when abnormal high torque occurs due to pipe deformation, thereby ensuring robust operation reliability of the valve even under extreme operating conditions based on a yield strength superior to that of general stainless steel.

[0031] In addition, according to the present invention, by providing a stacked assembly structure in which a seal, a bushing, a split ring, a thrust washer, and a retaining ring are sequentially combined in a stem support, the multi-support structure is provided to increase the rotational stability of the stem and effectively distribute axial loads, thereby completely blocking fluid leakage even in a high-pressure environment and preventing the detachment of assembly parts, so that consistent opening and closing performance can be guaranteed even during long-term repeated operation.

[0032] Furthermore, according to the present invention, by implementing precise linear contact through the organic combination of a sheet with a diagonal structure and a VR-processed disc, excellent airtightness performance can be achieved even with low closing force. Consequently, the present invention simultaneously ensures product durability and operational reliability even in harsh piping environments, thereby significantly contributing to reducing maintenance costs and enhancing safety in industrial sites. Brief explanation of the drawing

[0033] FIG. 1 is a perspective view of a piping interference prevention type butterfly valve according to one embodiment of the present invention. FIG. 2 is a perspective view showing the internal configuration of a piping interference prevention type butterfly valve according to one embodiment of the present invention. FIG. 3 is an exploded perspective view showing the assembly structure of a piping interference prevention type butterfly valve according to one embodiment of the present invention. FIG. 4 is a perspective view showing the assembled state of the core components inside the valve body in detail. FIG. 5 is a cross-sectional view of a key part of a piping interference prevention butterfly valve according to one embodiment of the present invention. FIG. 6 is a perspective view of a disk applicable to various embodiments of the present invention. FIG. 7 is an enlarged cross-sectional view showing the coupling relationship between the valve body, seat, and stem according to one embodiment of the present invention. FIG. 8 is a cross-sectional view of a key part showing the fully open state of a piping interference prevention type butterfly valve according to one embodiment of the present invention. FIG. 9 is a data sheet comparing the operating clearance by specification between a disk with a VR processing structure applied, which is the core technology of the present invention, and a disk with conventional technologies applied. FIG. 10 is a data sheet comparing the operating clearance (C) between the design improvement of the present invention and the prior art (S2x, S31) for large-diameter butterfly valve specifications ranging from 350A (14 inches) to 600A (24 inches). FIG. 11 is a cross-sectional view of a key part showing a mechanical coupling structure of a valve body and a seat according to another embodiment of the present invention. FIG. 12 is an exploded perspective view showing the stem support and sealing structure of a piping interference prevention type butterfly valve according to another embodiment of the present invention. FIG. 13 is a cross-sectional perspective view and an enlarged view showing the upper and lower arrangement structure of a stem bearing according to one embodiment of the present invention. In relation to the description of the drawings, the same or similar reference numerals may be used for identical or similar components. Specific details for implementing the invention

[0034] Hereinafter, various embodiments of the present invention are described with reference to the accompanying drawings. However, this is not intended to limit the present invention to specific embodiments and should be understood to include various modifications, equivalents, and / or alternatives of the embodiments of the present invention.

[0035] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0036] Additionally, terms such as “…part,” “…unit,” and “module” described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0037] Furthermore, throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components in between.

[0038] Furthermore, when a part is said to "include" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather may include additional components, and it should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0039] Pipes buried underground, especially flexible synthetic resin pipes such as polyethylene (PE) or polyvinyl chloride (PVC), are constantly subjected to the load of soil piled on top and dynamic loads from vehicles passing over the ground.

[0040] If such vertical external pressure exceeds the rigidity of the piping, a phenomenon called 'flattening' or 'ellipsing' occurs, in which the cross-section of the pipe, which should maintain a perfect circular shape, is compressed in the vertical direction and becomes flattened at the top and bottom. In this case, the vertical inner diameter of the pipe results in a substantial reduction compared to the design dimensions.

[0041] Furthermore, synthetic resin pipes exhibit repetitive thermal expansion and contraction behaviors due to changes in fluid temperature or differences in ambient temperature. In particular, if the pipe is not completely constrained and has a non-uniform temperature distribution, uniform expansion does not occur in the circumferential direction; instead, contraction concentrates along a specific axial direction, causing deformation in which the inner diameter of the pipe becomes distorted into an elliptical shape.

[0042] If a butterfly valve is opened when the inner diameter of the piping has sagged inward (upper compression) or narrowed due to the physical / environmental factors mentioned above, the following serious problems occur.

[0043] When a conventional disc with a right-angled corner structure rotates, its end comes into contact closest to the inner wall of the pipe, and at this time, the inner diameter surface of the deformed pipe encroaches into the rotational trajectory of the disc.

[0044] The sharp edge of the disc becomes physically jammed or stuck against the deformed inner wall of the pipe, making it impossible to fully open the valve. This induces excessive driving torque, which is a direct cause of stem deformation, gearbox failure, or permanent damage to the inner wall of the pipe.

[0045] In conclusion, the present invention assumes harsh field conditions in which piping is pressed vertically or deformed into an elliptical shape due to external loads or temperature changes.

[0046] When the disc passes through this 'lowered pipe ceiling (upper compression surface)', the top priority is to geometrically maximize the deformation margin so that it can stably reach a 90-degree fully open position without physical collision.

[0047] FIG. 1 is a perspective view of a pipe interference prevention type butterfly valve (1) according to one embodiment of the present invention. FIG. 2 is a perspective view showing the internal configuration of a pipe interference prevention type butterfly valve (1) according to one embodiment of the present invention. FIG. 3 is an exploded perspective view showing the assembly structure of a pipe interference prevention type butterfly valve (1) according to one embodiment of the present invention. FIG. 4 is a perspective view showing the state in which the core components inside the valve body (100) are assembled.

[0048] Referring to FIGS. 1 to 4, a pipe interference prevention butterfly valve (1) installed in a pipe (10) to control the flow of fluid according to the present invention comprises a valve body (100) having a fluid path formed in the center, a disc (200) rotatably installed within the fluid path of the valve body (100), a seat (110) disposed between the valve body (100) and the disc (200) to maintain airtightness, and a stem (250) connected to the disc (200) to transmit rotational force.

[0049] The above disk (200) is formed with a VR processing structure having a predetermined curvature, forming a radial clearance (C) defined as the shortest distance between the inner diameter surface of the pipe (10) and the edge of the disk (200).

[0050] At this time, due to the VR processing structure, the radial clearance (C) is formed to be greater than the thickness of the sheet (110) when the disk (200) is in a fully open state, and the sheet (110) is formed with a diagonal structure in which both sides of the inner diameter surface of the sheet (110) gradually taper toward the center so as to minimize the surface contact area when in contact with the VR processing surface formed by the curvature buffering shape of the VR processing structure.

[0051] A pipe interference prevention type butterfly valve (1) according to the present invention is installed between pipes (10) through which fluid is transported to control the flow of fluid.

[0052] Specifically, the present invention comprises a valve body (100) having a fluid path formed in the center, a disc (200) rotatably installed within the fluid path of the valve body (100), a seat (110) disposed between the valve body (100) and the disc (200) to maintain airtightness, and a stem (250) connected to the disc (200) to transmit rotational force.

[0053] The above valve body (100) is firmly connected to the pipe flanges (13) on both sides by a plurality of fastening bolts (30) and nuts (40) to form a watertight structure.

[0054] The valve body (100) adopts a 1PC structure and an upper body structure to enhance structural integrity and minimize body deformation caused by external impact or pressure.

[0055] Here, the 1PC structure refers to an integral structure in which the valve body (100), which is the body of the valve, is manufactured as a single casting or machined part without separate division or joining parts. This is a design method that contrasts with the 2PC (Two-Piece) or 3PC (Three-Piece) structure, which is assembled by fastening two or more parts with bolts or welding. By adopting the 1PC structure and upper body structure, the split body structure does not require a gasket or seal on the joining surface between parts, which is essential, and since the joining surface itself does not exist, the possibility of fluid leakage to the outside of the body can be structurally eliminated.

[0056] In addition, since the valve body (100) is manufactured as a single piece, it has superior resistance to external impacts, piping loads, or stress concentration caused by internal high-pressure fluid. This provides a geometric foundation that maintains the precise alignment of the valve, prevents eccentricity of the stem (250), and extends the life of the sealing parts.

[0057] The 1PC structure of a single material exhibits uniform thermal expansion behavior, thereby maintaining constant airtightness performance even in high and low temperature environments.

[0058] This 1PC structure, the upper body structure, refers to an extension that protrudes vertically upward from the main body housing, which is a passage through which fluid flows. This is a core frame that physically connects and supports the disc (200) and stem (250) located inside the fluid path and the external driving device (actuator, lever, gearbox, etc.) for the valve.

[0059] The above-described disk (200) is driven to open and close using the above-described stem (250) as a rotation axis according to the operation of the upper drive lever (20), and is characterized by having a VR processing structure and a radial clearance (C value) formed therein so that physical interference does not occur with the inner diameter surface of the pipe (10) even when the pipe (10) contracts or undergoes elliptical deformation.

[0060] The present invention is configured by adjusting the gear ratio one step upward compared to the existing one, taking into account the high operating torque generated in large-diameter valves of 350A (14 inches) or larger.

[0061] This design mechanically amplifies the operating torque required to open and close the disk (200), thereby minimizing the user's operating force, and acts complementarily with the physical resistance reduction effect of the aforementioned VR processing structure.

[0062] Thus, the user's operating force is reduced, and precise opening control is enabled. In particular, by creating synergy with the torque reduction effect of the aforementioned VR machining structure, smooth valve operation can be realized even in extreme conditions.

[0064] FIG. 5 is a cross-sectional view of a key part of a piping interference prevention type butterfly valve (1) according to one embodiment of the present invention.

[0065] Referring to FIG. 5, a seat (110) for blocking fluid flow is seated on the inner side of the valve body (100), and a disc (200) is rotatably installed at a position corresponding to the inner diameter surface of the seat (110). At this time, a stem (250) for transmitting rotational force to the disc (200) is connected through the center of the disc (200).

[0066] A state is illustrated in which the outer diameter end of the disc (200) contacts the seat (110) provided on the inner side of the valve body (100) to close the flow path. In particular, the edge of the disc (200) is formed with a VR processing structure having a gentle curvature, rather than a general wedge shape.

[0067] This VR processing structure relieves stress concentration when in contact with the inner diameter surface of the seat (110), thereby preventing damage to the seat (110), and minimizes the friction area with the seat (110) at the point when the disk (200) begins to rotate, so that smooth opening and closing is possible even with low torque.

[0068] In particular, the VR processing structure formed at the edge end of the disk (200) induces precise linear contact when in contact with the sheet (110), thereby ensuring airtightness and minimizing operating torque. Additionally, the stem (250) is made of the aforementioned high-strength precipitation-hardened stainless steel material, so that it stably transmits driving force without torsional deformation even when the disk (200) is in close contact with the sheet (110) or when a load occurs due to pipe deformation.

[0069] The material of the sheet (110) may be FKM (Fluoroelastomer), a fluororubber material. This possesses superior heat resistance and chemical resistance compared to general elastomers, preventing expansion or deterioration of the sheet even when transporting high-temperature fluids or corrosive chemicals, and ensuring long-term airtightness reliability.

[0070] In addition, the stem according to the present invention is a key component that transmits rotational torque generated when the disc is opened or closed. In particular, if unexpected foreign matter enters the pipe or if pipe deformation occurs due to external load, the rotational resistance of the disc increases rapidly.

[0071] At this time, if excessive driving force is applied by the operator, torsional stress exceeding the allowable dimensions is concentrated on the stem, posing a risk of permanent physical deformation or breakage.

[0072] The present invention has made improvements to a high-strength material to ensure the driving stability of the stem even in such extreme environments. The stem (250) of the butterfly valve according to the present invention is made of a precipitation-hardened stainless steel material to maintain torsional rigidity even in harsh driving environments. This is to ensure that rotational force is transmitted stably without permanent deformation or breakage of the part, even if the eccentric load applied to the disc (200) during elliptical deformation of the pipe (10) is transmitted to the stem (250).

[0073] That is, the above stem (250) is made of a precipitation-hardened stainless steel material and contains, in weight percent, chromium (Cr): 15.0 to 17.5%, nickel (Ni): 3.0 to 5.0%, copper (Cu): 3.0 to 5.0%, and the remainder is iron (Fe) and other unavoidable impurities, so that torsional deformation of the stem can be suppressed even under eccentric load caused by deformation of the pipe (10).

[0074] Chromium (Cr: 15.0 ~ 17.5%) provides corrosion resistance, which is a basic characteristic of stainless steel, and at the same time prevents corrosion of the stem surface even in high temperature and high pressure fluid environments, thereby ensuring long-term operational stability.

[0075] Nickel (Ni: 3.0 ~ 5.0%) stabilizes the structure of the alloy and improves toughness, protecting the stem from brittle fracture (breakage) during sudden torque changes.

[0076] Copper (Cu: 3.0 ~ 5.0%) is a key element of this material and plays a role in dramatically increasing the strength of the underlying structure by precipitating fine copper particles during the heat treatment process. Through this, significantly higher yield strength compared to general stainless steel can be achieved.

[0077] Remainder iron (Fe) and other impurities: Forms the basic basis of the material, and minimizes impurities such as phosphorus (P) or sulfur (S) to ensure the homogeneity of the material.

[0078] When the pipe (10) is deformed by external compression, the central axis of the valve is slightly misaligned and an unbalanced eccentric load is applied to the stem (250). Based on the high strength characteristics according to the alloy composition, the stem (250) of the present invention effectively suppresses torsional deformation of the stem even under such eccentric load.

[0079] Consequently, this is combined with the core technologies of this invention—VR machining and disc miniaturization design—to complete a 'structural synergy' in which the disc avoids pipe walls while the stem supports it with strong force. In particular, since axial twisting of the stem does not occur even when the operator applies excessive torque to open or close the valve, precise control of valve opening and closing is always possible.

[0080] Thus, the yield strength of the conventional stem, 205 Compared to, maximum 1175 It recorded a yield resistance of more than three times. This means that the elastic limit at which the stem returns to its original shape even after being subjected to torsional load has been dramatically expanded.

[0081] The tensile strength is also the existing 520 Up to 1310 It has been improved by more than 2.5 times, maximizing the mechanical limit at which the stem can withstand excessive torque without breaking.

[0082] The high-strength stem design according to the present invention is combined with the VR processing and disc miniaturization technologies, which are the core of the invention, to form a dual safety mechanism. That is, VR processing reduces the fundamental probability of interference between the disc and the pipe wall, while the high-strength stem stably transmits rotational force without structural deformation even in the event of high torque, thereby ensuring optimal driving reliability even in large pipeline environments.

[0084] FIG. 6 is a perspective view of a disk (200) applicable to various embodiments of the present invention.

[0085] Referring to FIG. 6, the disk (200) of the present invention can be made of a material optimized according to the type, temperature, and pressure conditions of the fluid being transported.

[0086] For example, in environments where the fluid is highly corrosive, a stainless steel disc can be used, and a disc coated with nylon or epoxy can be optionally used to improve wear resistance and fluidity.

[0087] The material of the disc (200) is SS316 (stainless steel 316) as the base metal to ensure excellent mechanical strength, and at the same time, ECTFE (Halar coating) treatment is applied to the surface. This completely protects the disc from extreme corrosive environments such as strong acids and strong alkalis and reduces flow friction resistance.

[0088] Regardless of which material is selected, a common feature of all discs (200) illustrated in FIG. 6 is that the edge ends are formed with a VR processing structure that is curvature-buffering. As previously described, this structural feature performs the key function of preventing interference with the pipe (10) when open and reducing operating torque while maintaining airtightness with the seat (110) when closed.

[0089] Additionally, a stem hole is vertically formed in the central part of the disk (200) so that a stem (250) can be inserted and connected through it, and is designed to accommodate rotational force transmitted from the high-strength stem (250) without loss.

[0090] The disc (200) of the present invention has a precision engineering structure designed to minimize the contact area with the seat (110). Specifically, a VR machining structure formed on the outer edge of the disc (200) converts the contact area between the disc and the seat from a conventional surface contact method to a line contact method. This reduction in the contact area drastically lowers the frictional resistance generated during opening and closing, enabling smooth operation even with low driving torque, while simultaneously providing the effect of minimizing mechanical wear of the seat.

[0091] In addition, the disc (200) according to the present invention can provide an optimized design according to the operating pressure conditions of the installed piping. As shown in FIG. 6, embodiments according to the present invention can have the thickness, curvature, and material stiffness of the disc precisely adjusted to correspond to different pressure conditions such as 50 psi, 175 psi, and 250 psi.

[0092] This ensures technical flexibility to respond to the requirements of various industrial sites by ensuring that the disc (200) is not deformed by the fluid pressure even in a high-pressure environment (e.g., 250 psi) and maintains a stable close contact with the sheet (110).

[0093] In addition, this pressure-grade optimized design is organically combined with the aforementioned high-strength stem (250) and stacked support assembly, enabling long-term driving reliability to be secured without twisting of the stem or detachment of the disc even under high-pressure loads.

[0095] FIG. 7 is an enlarged cross-sectional view showing the combined relationship of the valve body (100), seat (110), and stem (250) according to one embodiment of the present invention.

[0096] Referring to FIG. 7, the seat (110) according to the present invention is integrally formed on the inner diameter surface of the valve body (100). In particular, the sides of the inner diameter bore of the seat (110) are formed in a diagonal structure that gradually narrows toward the center and then widens again toward the outside.

[0097] This diagonal structure serves to significantly reduce the operating torque of the valve by optimizing the contact point with the seat (110) when the disc (200) rotates to the closed position and reducing the unnecessary friction area.

[0098] In addition, the seat and body structure at the point where the stem (250) penetrates can be designed in the shape of a spherical hub. This spherical structure not only stably supports the rotation of the stem (250) but also enhances sealing performance by effectively blocking stem leaks in the stem support portion even when fluid pressure is applied. Furthermore, combined with the aforementioned high-strength stem (250) material, it enables precise opening and closing control without mechanical deformation even in high-pressure environments.

[0100] FIG. 8 is a cross-sectional view of a key part showing the fully open state of a piping interference prevention type butterfly valve (1) according to one embodiment of the present invention.

[0101] Referring to FIG. 8, the disk (200) is rotated 90 degrees around the stem (250) as an axis, so that the flow path is fully opened. At this time, the outer end of the disk (200) is aligned so as not to obstruct the flow of fluid by being spaced apart from the seat (110) inside the valve body (100).

[0102] The disc (200) of the present invention has a streamlined cross-section that gradually tapers from the center to the end, thereby minimizing flow resistance. In particular, the VR processing structure formed on both edges of the disc (200) provides a geometric foundation that can secure a safe operating space (gap) without physical collision even if pipe shrinkage or elliptical deformation exists when it faces the inner diameter surface of the pipe (10) in an open state as shown in FIG. 8.

[0103] Specifically, the disk (200) of the present invention has a unique 'geometric variable cross-sectional structure' to simultaneously achieve the minimization of flow resistance and the fundamental blocking of pipe interference.

[0104] First, the overall cross-sectional shape of the disk (200) forms an airfoil-based streamlined structure in which the thickness is greatest in the central part through which the stem (250) passes, and the thickness decreases symmetrically toward the outer diameter end. This structure suppresses fluid separation when the flow path is opened, thereby drastically lowering the pressure drop value indicating pressure loss, and effectively controls vibration and noise caused by vortices generated on the back of the disk even in high-velocity environments.

[0105] In particular, the VR processing structure provided at both ends of the disk (200) means a cushioned geometric structure in which a curved surface having a specific radius of curvature is continuously formed along the entire circumference of the disk, going beyond simply cutting the ends.

[0106] As shown in FIG. 8, when the valve is fully open, the outer end of the disc (200) is positioned parallel to the inner surface of the pipe (10). At this time, conventional standard discs have an extremely narrow gap with the inner diameter of the pipe, so immediate interference occurs even with minute pipe deformation; however, the VR processing structure of the present invention can additionally secure a 'C (Clearance) value,' which is a radial operating clearance space, by removing the corner portion of the disc end through a curvature design.

[0107] The VR processing structure of the disk (200) according to the present invention is formed continuously over the entire outer circumference (360°) of the disk, including the hub region adjacent to the stem (250), thereby geometrically blocking the possibility of physical collision that may occur when the pipe (10) is deformed.

[0108] Generally, when the butterfly valve is fully open, the part closest to the inner diameter surface of the pipe (10) is the hub area on the side of the stem (250) penetration, which is formed to be the thickest for the structural rigidity of the disc (200).

[0109] Conventional standard discs have a limitation in that the end edge of the corresponding part is formed to be close to a right angle or sharp, causing immediate interference and valve sticking accidents when slight contraction or oval deformation (Ovality) of the pipe (10) occurs.

[0110] Specifically, the discs applied to conventional standard butterfly valves were generally formed with outer diameter ends that were nearly right-angled or had very sharp wedge shapes to ensure ease of manufacturing and simple sealing force upon full closure. However, this geometric structure exposes the following critical limitations in actual piping operating environments.

[0111] First, there is an absolute lack of clearance to accommodate pipe deformation. In the fully open state, the gap between the standard disc and the inner diameter of the pipe is set to be extremely tight according to design dimensions. Consequently, if elliptical deformation occurs due to minute thermal shrinkage caused by temperature changes or earth pressure, the sharp edges of the disc immediately come into contact with the inwardly protruding inner wall of the pipe. Particularly in the case of synthetic resin or lined pipes, which have higher deformation rates compared to metal pipes, this protruding structure of the edges becomes the primary cause that effectively eliminates any operational clearance in the event of pipe deformation.

[0112] Second, it causes physical seizure and failure to operate. When the sharp edges of the disc come into physical contact with the deformed inner wall of the pipe, a 'wedge phenomenon' occurs where the edges dig into or get stuck in the pipe wall, going beyond simple friction. Once this interference occurs, the system falls into a seized state where rotational operation to close the valve becomes impossible. This leads to an uncontrollable state due to the failure to block the flow path in an emergency, seriously threatening the safety of the entire system.

[0113] Third, there is an increased risk of secondary failure of the stem and drive components. When the valve is forcibly operated while the disc is stuck due to interference with the piping, the excessive rotational force transmitted from the drive unit is concentrated as a torsional load on the stem. In conventional standard structures, secondary structural defects frequently occur where the stem permanently twists or breaks because it cannot withstand such abnormally high torque. This results in massive repair costs and production interruption losses, requiring the entire piping line to be cut and replaced, going beyond simple valve maintenance.

[0114] To solve this, the VR processing structure of the present invention is designed by replacing the sharp edge portion of the outer diameter of the disk (200) with a curved surface having a specific radius of curvature. This geometric shape design provides the effect of substantially increasing the radial clearance (hereinafter 'C value'), which is the shortest distance between the inner diameter surface of the pipe (10) and the outer diameter end of the disk (200) when fully opened.

[0115] Specifically, when the disc (200) is aligned parallel to the Euro, the point facing the inner wall of the pipe (10) is changed from a conventional sharp corner point to a curved point that is gently cut inward by the curvature, thereby increasing the deformation threshold allowed for the inner wall of the pipe to contact the disc.

[0116] Here, the deformation threshold refers to the maximum allowable deformation amount of a pipe such that normal opening and closing operation can be maintained without physical interference between the rotational trajectory of the disk (200) and the inner wall of the pipe (10) when the inner diameter shape of the pipe (10) changes from the initial design value due to external pressure or temperature change.

[0117] Conventional discs with sharp edges have a narrow gap with the inner wall of the pipe, so even minute deformation causes the valve to reach a critical threshold, thereby causing valve sticking. However, the present invention dramatically increases the critical threshold for pipe contraction and elliptical deformation by expanding the radial clearance (C value) through a VR processing structure.

[0118] In addition, the VR processing structure of the present invention physically improves the friction characteristics that occur when the disk (200) starts rotating, thereby maximizing the initial driving efficiency.

[0119] First, there is a significant reduction in maximum static friction force. When the valve is switched from a closed state to an open state, a so-called 'break-away torque' is generated to overcome static friction resistance between the disc (200) and the seat (110).

[0120] The present invention converts the contact area with the sheet (110) from a conventional surface contact to a line contact or narrow contact method by making the contact shape of the end of the disc curved through VR processing. This minimizes the maximum static friction force that must be overcome during initial operation, thereby enabling smooth initial detachment without placing an excessive load on the drive device.

[0121] Second, there is a sliding-inducing effect due to the curved shape. In a conventional structure where the end of the disk (200) is at a right angle, a large compressive stress acts to vertically dig into or crush the seat (110) at the start of rotation, causing a rapid increase in driving resistance, whereas the rounded VR shape of the present invention performs a cam action that slides smoothly along the elastic surface of the seat (110).

[0122] These geometric characteristics convert the mechanical interference that occurs when the disc (200) is separated from the seat (110) into 'sliding contact,' thereby substantially lowering the friction coefficient and ensuring linearity of the valve opening and closing operation. Consequently, even in environments where the compressive force between the disc and the seat is abnormally high due to pipe deformation, the present invention prevents the valve from sticking and enables stable driving performance through a self-sliding effect using a rounded shape.

[0123] As a result, even if the inner diameter of the pipe (10) made of synthetic resin material such as polyethylene (PE) shrinks due to a decrease in ambient temperature or undergoes elliptical deformation due to earth pressure and is locally reduced, the value of C within the radial clearance expanded by the VR processing structure ensures a sufficient non-interference area within the rotational trajectory of the disk (200), thereby maintaining the rotational trajectory of the disk (200).

[0124] Therefore, by blocking the direct transmission of the deformation load of the piping to the disc, the valve's sticking accident is fundamentally prevented, and even under the same external load conditions, the present invention possesses a significantly higher deformation tolerance capacity compared to conventional technology, which serves as a key technical indicator that guarantees the operational reliability of the system even under harsh earth pressure or cryogenic environments. In particular, by fundamentally preventing the direct transmission of mechanical load due to pipe deformation to the disc in the area adjacent to the stem (250), where the risk of interference is highest, it is possible to maintain constant operational reliability and airtightness performance of the valve under any piping conditions.

[0125] In addition, the stem (250), which is visible in cross-section, is firmly seated in the central thick portion of the disk (200), thereby suppressing vibration or eccentricity of the disk even in high velocity or high pressure fluid flow and maintaining a stable driving state.

[0127] FIG. 9 is a data sheet comparing the operating clearance by specification between a disk (200) to which the VR processing structure, which is the core technology of the present invention, is applied and a disk to which conventional technologies are applied.

[0128] Referring to FIG. 9, the technical advantage secured by the present invention in a pipe deformation environment can be numerically demonstrated through this embodiment.

[0129] 1. Definition of Measurement Variables and Symbols

[0130] As illustrated in the reference diagram of Fig. 9, each measurement item has the following engineering significance.

[0131] (1) Symbol A (Stub-end ID(Inside Diameter)): It is the actual effective inner diameter of the stub end where the valve is installed. In the present invention, it is defined as the reference dimension of the space in which the disc (200) is received.

[0132] (2) Symbol B (Flange OD (Outside Diameter)): It is the outermost diameter of the flange or stub end connected to the piping.

[0133] (3) Symbol C (gag): It refers to the radial separation distance, which is the shortest radial distance between the inner diameter (A) of the stub end and the outer diameter (D) of the disc. This is the most critical indicator for determining the deformation threshold defined in the present invention, and a higher value indicates higher resistance to pipe deformation.

[0134] (4) Symbol D: This is the actual outer diameter (diameter) of the disc (200) to which VR processing has been applied. In the present invention, it has a value that is intentionally reduced compared to the inner diameter (A) of the stub end to accommodate the deformation threshold of the pipe.

[0135] (5) Symbol E (Pipe ID): It is the outermost diameter of the connected pipe body.

[0137] In the present invention, symbol A (stub end inner diameter) refers to the actual effective diameter inside the stub end in which the disk (200) is received, whereas symbol D (disk outer diameter) refers to the geometric diameter of the disk body that is intentionally designed to be reduced compared to symbol A through VR processing.

[0138] In particular, the improved product of the present invention is characterized by forming the edge portion of the disc into an optimal curvature through VR processing, while simultaneously forming the outer diameter (D) of the disc itself to be significantly smaller than the inner diameter (A) of the stub end.

[0139] This intentional reduction of the outer diameter (D) of the disc physically maximizes the radial clearance (C) between the inner wall of the pipe and the end of the disc, and the resulting gap is filled by the compressive restoring force of the thick elastic sheet (110), which acts as a key mechanism to maintain airtightness and induce the sheet to absorb and buffer interference stress during pipe deformation.

[0140] The VR processing structure of the present invention is characterized by rounding the upper and lower leading edges of the outer surface of the disk (200), which face the inner wall of the pipe (10) when fully opened, with a constant radius of curvature (R).

[0141] This is to ensure an operating clearance (C) with the inner wall of the pipe by physically reducing the maximum rotational trajectory (D) drawn by the end of the disc when the disc (200) rotates around the stem (250) and enters the pipe.

[0142] The VR processing of the present invention curves the edge portion formed by the thickness of the disc (200), thereby structurally retracting the point where the leading edge of the disc is closest to the inner wall of the pipe even when fully opened.

[0143] This increases the radial clearance (C) by shifting the actual outer line facing the inner diameter surface of the pipe inward, while preserving the central thickness that maintains the mechanical strength of the disc. As a result, it provides a deformation threshold that allows the tip of the disc to stably reach a 90-degree fully open position without catching on the pipe wall, even under conditions of thermal expansion or contraction due to earth pressure.

[0144] Additionally, the radial clearance (C) defined in the present invention refers to the shortest distance between the inner diameter surface of the pipe (10) and the rounded curved portion (R) of the tip of the disc (200) where physical interference is expected when the valve is opened.

[0145] In conventional right-angle corner structures, the sharp tip formed by the thickness of the disc is located closest to the inner wall of the pipe, which limits the ability to secure clearance; however, the present invention removes this portion with a constant curvature, thereby retracting the actual interference point inward in the radius of the disc.

[0146] As a result, the clearance C provides a stable driving threshold even during pipe deformation by expanding the actual clearance of the outermost trajectory facing the inner wall of the pipe during rotation and opening, regardless of the geometric length of the disk centerline.

[0147] The radial clearance defined by the symbol C in the present invention is a value measured based on the shortest distance point closest to the inner wall of the pipe among any points on the curved front portion (R) of the disk that faces the inner diameter surface of the pipe (10) during the process of the disk (200) opening or rotating.

[0148] Although the aforementioned tip curved surface forms a gentle curvature, the actual interference point is formed by retracting a certain distance in the direction of the disk's center axis compared to the virtual right-angle corner vertex before processing, thereby securing an expanded operating clearance space between it and the inner diameter surface of the pipe.

[0149] 2. Setting the Comparison Group

[0150] In this data sheet, the following four groups were compared to clarify the effects of the present invention.

[0151] (1) S2x (V-Cutting): It is a conventional general processing method with sharp edges that are close to a right angle.

[0152] (2) S31 (VR processing): It is a standard curved product existing in the market or a ready-made product that does not reflect optimized design specifications.

[0153] (3) Design improvement product (present invention): An embodiment of the present invention, which optimizes end curvature and processing angles in consideration of pipe deformation, is designed specifically for PE (polyethylene) pipe environments with severe deformation.

[0154] Performance measurement and design optimization of the ‘Design Improvement Product’ according to the present invention were performed based on high-density polyethylene (HDPE, hereinafter ‘PE’) pipes and corresponding stub end specifications, which are currently the most widely used in water supply and sewage and industrial piping lines.

[0155] The above improved product data is the result derived by reflecting the standard dimensions unique to PE piping (thick wall thickness and relatively narrow effective inner diameter according to SDR standards).

[0156] The technical reason for selecting the PE piping of the 'Design Improvement Product' according to the present invention as the standard specification is as follows.

[0157] a. High ductile strain (Flexibility & Deformation) due to external pressure

[0158] PE pipes have a lower elastic modulus compared to metal or PVC pipes, resulting in greater flexibility against external loads. Consequently, when buried underground, they are most likely to undergo ovalization (elliptical cross-section deformation) due to soil pressure or overhead loads; this deformation is the primary cause of disc sticking in butterfly valves. Therefore, the fundamental design objective of this invention is to overcome the PE piping environment, which is subject to the most severe deformation.

[0159] B. Dimensional instability due to thermal shrinkage and expansion

[0160] PE material has a relatively high coefficient of thermal expansion, so the inner diameter of the pipe changes frequently depending on the temperature of the fluid or seasonal factors. In particular, the contraction of the pipe that occurs when transferring cold water in winter causes the clearance with the disc to narrow rapidly, and the improved product is designed to ensure a stable operating clearance (C) even under such thermal contraction conditions.

[0161] C. Interference characteristics with Stub End structures

[0162] The stub end, which is essential for connecting PE pipes, often has a shape that protrudes inward to maintain pipe strength, so it is physically positioned closest to the rotational trajectory (D) of the disc. The present invention aims to demonstrate technical completeness by securing a clearance of more than twice that of the conventional technology, even in PE stub end specifications where the risk of interference is maximized.

[0163] In other words, the fact that the data for the improved product of the present invention was calculated based on PE piping means that operational reliability in the harshest and most frequently deformed piping environments was verified first.

[0164] This technically implies that while the sticking problem in PE piping environments is completely resolved, an even greater safety margin can be achieved in metal pipe or PVC piping environments with lower strain rates (refer to the PVC column in the table).

[0165] (4) PVC (VR processed): This is a variable embodiment in which the technology of the present invention is applied to suit PVC (polyvinyl chloride) piping environments with different inner diameter specifications.

[0167] Here, the 'PVC (VR processing)' column of the table shown in FIG. 9 is an example where the material of the target pipe combined with the metal valve body is PVC. This represents actual measurement data with the VR processing and disc outer diameter (D) reduction design of the present invention applied based on the intrinsic inner diameter (A) of the PVC pipe.

[0168] Even if PVC pipes have the same nominal diameter (e.g., 100A, 200A, etc.), the actual value and shape of the stub end inner diameter (A) differ from those of general carbon steel pipes or PE pipes.

[0169] In particular, due to the thickness design specifications unique to PVC material, the inner diameter (A) of the stub tends to be formed relatively narrow compared to pipes made of other materials. However, the present invention is designed to flexibly reduce the outer diameter (D) of the disc without being dependent on such variations in inner diameter by material, thereby ensuring optimal operating clearance (C) in the inner space of the stub end at all times.

[0170] This demonstrates the unique technical flexibility of the present invention, which can universally solve the problem of disc sticking caused by pipe deformation regardless of the type of pipe material.

[0171] The present invention demonstrates that it possesses design variability capable of securing an optimal radial operating clearance (C value) in each environment by taking into account these dimensional differences according to pipe materials.

[0172] 3. Results of comparative analysis of operating play (C) by specification

[0173] Measurement results confirmed that the design-improved product of the present invention secures an overwhelming clearance compared to conventional technology in all specifications.

[0174] (1) Medium to small diameter (100A~150A) range:As a result, based on the 100A standard, the clearance (C) of the conventional S2x method is 5.9mm, whereas the improved product of the present invention secures 10.1mm, achieving an increase in clearance of more than 71%. This implies a sufficient safety margin that can completely prevent disc interference even under conditions of minute earth pressure deformation.

[0175] In this embodiment, symbol A represents the effective inner diameter of the stub end where the valve is installed, and symbol D represents the outer diameter of the disc (200) to which VR processing is applied.

[0176] Referring to the 100A standard, in an environment where the inner diameter (A) of the stub end is 101 mm, the outer diameter (D) of the disc of the present invention is designed to be 93 mm. This is a point of differentiation from the conventional S2x (102 mm) or S31 (103 mm) methods, which maintain a tight seal using a disc larger than the inner diameter of the pipe.

[0177] The present invention maximizes the radial clearance (C), which is a physical separation space between the two, by designing the outer diameter (D) of the disc to be reduced to about 90% of the inner diameter (A) of the stub end.

[0178] The clearance (C) produced in the improved design reaches 10.1 mm, which is a value that is expanded by more than twice the clearance (4.8 mm) of the conventional S31 method. This overwhelming clearance provides a 'non-interference driving area' in which the disc (200) can rotate without physically colliding with the inner wall of the pipe, even when the pipe undergoes elliptical deformation or pipe twisting due to ground subsidence.

[0179] The radial gap of about 8 mm, which occurs as the outer diameter (D) of the disc is formed to be significantly smaller than the inner diameter (A) of the stub end, is compensated for by increasing the thickness of the high-elasticity sheet (110) provided inside the valve body (100).

[0180] That is, the present invention is designed so that the thickness of the sheet (110) is formed thickly to correspond to the size of the gap (C), so that when closed, the disc (200) compresses the thick sheet layer and maintains perfect airtightness, and when opened, the sheet's restoring force range is quickly escaped through the VR processing structure and the small disc diameter.

[0181] This structure induces a 'cushion effect' in which the sheet (110) primarily absorbs and buffers the external force generated during pipe deformation, and consequently serves as a technical foundation for fundamentally blocking the phenomenon of the disc sticking.

[0182] (2) Medium-sized (200A) section: The improved product of the present invention achieves a clearance (C) of 12.6 mm, thereby achieving a significant numerical advantage over the conventional S2x (6.6 mm) and the existing S31 product (7.8 mm). This serves as a practical technical means to prevent the valve from sticking even in extreme environments where the piping is compressed into an elliptical shape.

[0183] (3) Large diameter (300A) section: Due to the characteristic that it becomes difficult to secure clearance as the diameter increases, the existing S31 product exhibited an extremely dangerous clearance of 2.7 mm, but the improved product of the present invention maintains 7.7 mm, thereby dramatically improving the operational reliability of the large-diameter piping system.

[0184] 4. Technical Significance and Conclusion of the Present Embodiment

[0185] The data in FIG. 9 shows that the present invention does not merely stop at rounding the edges of the disc, but implements an optimal design that maximizes the 'radial operating clearance' by considering the standard inner diameter and deformation characteristics of the connected pipe material (PE, PVC, etc.).

[0186] In other words, data analysis results show that the VR processing structure of the present invention maintains significantly greater clearance compared to conventional technology, even in a PVC piping environment.

[0187] First, based on the 100A standard, the clearance (C value) in the PVC specification is measured at 11.6mm, securing more than twice the clearance compared to the existing S2x method (5.9mm) or S31 method (4.8mm).

[0188] Second, by maintaining a clearance of 10.2mm in the PVC specification based on the 200A standard, interference with the disc is completely avoided even in situations of minute deformation that may occur due to the characteristics of PVC pipes, which are vulnerable to impact because the material has low elasticity.

[0189] The above data demonstrates that the VR processing structure of the present invention is not limited to specific pipe materials and can be universally applied to various piping systems, such as PVC, PE, and metal pipes. In other words, by flexibly designing the curvature and outer diameter (A value) of the disc in response to the inner diameter (E value) that varies depending on the pipe material, this data proves unrivaled technical adaptability that enables the stable securing of the maximum deformation threshold in any installation environment.

[0190] In particular, the fact that it maintains significantly higher clearance values ​​than conventional technology in both PE piping environments with severe shrinkage and expansion (improved product series) and PVC piping environments with relatively high rigidity (PVC series) demonstrates that the present invention is universally applicable to various piping systems and can perfectly satisfy different deformation threshold requirements.

[0191] Consequently, this dramatic increase in clearance reduces the maximum static friction force during initial actuation and, combined with a sliding induction effect that avoids physical interference with the inner wall of the pipe, serves as the key basis for preventing valve sticking and ensuring long-term operational stability even in harsh environments.

[0193] FIG. 10 is a data sheet comparing the operating clearance (C) between the design improvement of the present invention and the prior art (S2x, S31) for large-diameter butterfly valve specifications ranging from 350A (14 inches) to 600A (24 inches).

[0194] Large-diameter piping systems have a higher fluid flow rate and a larger surface area exposed to external pressure (earth pressure) compared to medium and small diameters, so the amount of ovalization of the piping is absolutely large. In particular, in conventional technology, the rotational trajectory (D) of the disc is designed to be extremely close to the inner diameter (E) of the pipe, so there was a chronic problem where the valve would become completely stuck even with only minute deformation.

[0195] As a result of analyzing the numerical data in Fig. 10, it was demonstrated that even in the large diameter section, the VR processing structure of the present invention secures a margin of space that surpasses conventional technology.

[0196] First, while the clearance (C) of the 350A standard and the conventional S2x method is 6.9mm, the improved product of the present invention secures 14.5mm, achieving a dramatic increase in clearance of more than 110%.

[0197] Second, particularly in the case of the 450A standard and critical section specifications, the conventional S2x method showed a structural limitation in which the clearance (C) value converged to '0', causing immediate interference when the pipe was deformed. However, the improved product of the present invention ensures a clearance of 11.6 mm under the same conditions, thereby perfectly guaranteeing operational safety in large pipelines.

[0198] Third, in the case of the 600A standard and large diameter section specifications, in contrast to the existing S31 product which could not cope with the large deformation amount characteristic of large diameters due to an extremely narrow clearance of 3.0 mm, the improved product of the present invention maintains a stable clearance of 9.1 mm.

[0199] As specified in the table shown in FIG. 10, the improved product of the present invention is characterized by reducing the outer diameter (D) of the disc by about 10 mm to 15 mm compared to the prior art in all specifications. This is the result of miniaturizing the geometric diameter of the disc body itself along with the tip curvature through VR processing, thereby retracting the interference point from the inner wall of the stub end toward the center.

[0200] The clearance (C) expanded by these design features acts as a 'physical escape route' that allows the disc (200) to rotate smoothly without being constrained by the pipe wall even when the upper part of the pipe is compressed and elliptically deformed by an external load, and consequently ensures stable opening and closing of the valve without sticking in any adverse pipeline environment.

[0201] In conclusion, the data in Fig. 10 shows that the VR processing technology of the present invention precisely targets the severe deformation characteristics of large-diameter pipes.

[0202] In particular, the average clearance (C) of 10 mm or more secured by the present invention in large diameter specifications of 350 A or more represents an overwhelming deformation threshold that can fundamentally prevent valve sticking even in environments involving soil pressure during underground burial or vibration during the transfer of large volumes of fluid. Combined with the aforementioned gear ratio upward design, this serves as the key basis for simultaneously achieving high driving reliability and low-torque operability required in large industrial sites.

[0203] Here, the curvature (R) of the VR processing structure is formed to have a range of 0.5T to 1.5T relative to the maximum thickness (T) of the disk, and the outer diameter (D) of the disk (200) is formed to have a diameter reduced by 5% to 12% relative to the effective inner diameter (A) of the stub end, and the radial clearance (C) is formed by the difference between the inner diameter (A) of the stub end and the outer diameter (D) of the disk, and is formed to have a size of 1.2 to 2.0 times the thickness of the sheet (110), so that airtightness is maintained through elastic compression of the sheet (110) even in the case of elliptical deformation of the pipe (10), and at the same time, an interference-free rotational trajectory of the disk (200) can be guaranteed.

[0204] That is, a unique VR processing structure is formed on the outer periphery of the disk (200) according to the present invention, and the processing curvature (R) is limited to a range of 0.5T to 1.5T based on the maximum thickness (T) of the disk.

[0205] This curvature limitation is intended to form an optimal compression profile necessary for maintaining airtightness and reducing frictional torque by minimizing the contact area with the inner wall of the pipe during rotation, while maintaining the structural rigidity of the disc.

[0206] The key numerical feature of the present invention is that the actual outer diameter (D) of the disk is formed to be significantly smaller than the effective inner diameter (A) of the stub end, which is the installation space. Specifically, the outer diameter (D) of the disk is designed to have a diameter reduced by 5% to 12% relative to the inner diameter (A).

[0207] This is a strategic design intended to fundamentally resolve the "seizure problem during pipe deformation" caused by conventional technology adopting large discs close to the inner diameter to enhance airtightness. In other words, by making the disc itself smaller, it preemptively secures an "absolute operating space" that prevents the disc from being constrained by the pipe wall even if elliptical deformation occurs.

[0208] The radial clearance (C) formed by the difference in diameter between A and D is managed to a size corresponding to 1.2 to 2.0 times the thickness of the sheet (110) in the present invention.

[0209] The technical significance of these numerical limitations is as follows. As the disc becomes smaller, the wide gaps that occur are filled by a sheet (110) made of a high-elasticity material. When closed, the elastic restoring force of the thickly formed sheet (110) is utilized to maintain perfect airtightness even with a small disc, and when opened, the disc rotates and the compressed state of the sheet is quickly released.

[0210] As a result, even when the pipe (10) is compressed by external pressure, the thick sheet (110) acts as a shock absorber to accommodate the deformation of the pipe wall, thereby ensuring an interference-free rotational trajectory of the disc (200) and completely preventing the valve from sticking.

[0211] Meanwhile, the above VR processing structure is variably designed to correspond to changes in the inner diameter (A) of the stub end according to the material of the pipe (10), and the clearance when applying a PE pipe of a flexible material ( ) and clearance when applying rigid PVC piping ( The ratio of ) The outer diameter (D) and curvature (R) of the disk are adjusted so that the range of 0.8 to 1.2 is maintained, thereby ensuring the same level of operational safety margin even in piping environments with different strain and inner diameter dimensions.

[0212] Depending on site conditions, various materials such as ductile PE (Polyethylene) pipes or rigid PVC (Polyvinyl Chloride) pipes are selectively applied to piping systems where butterfly valves are installed.

[0213] Even if these materials have the same nominal diameter, the inner diameter (A) of the stub end and the strain caused by external load differ due to the inherent stiffness of the material and manufacturing tolerances.

[0214] Considering the variability of such piping environments, the present invention proposes a variable design optimized for the pipe material, rather than a design fixed to specific specifications.

[0215] The present invention precisely adjusts the disc outer diameter (D) and VR machining curvature (R) according to the pipe material. This is the clearance calculated when applying PE pipe, which is a flexible material. ) and clearance when applying rigid PVC piping ( The ratio of ) The purpose is to ensure that ) maintains an equal level in the range of 0.8 to 1.2, that is, practically close to 1:1.

[0216] Generally, PVC pipes have a narrower inner diameter (A) compared to PE pipes but a lower strain, while PE pipes have a wider inner diameter but a higher compression strain. By analyzing these conflicting characteristics, the present invention forcibly forms a radial clearance (C) equivalent to that of a PE environment in a PVC environment by further miniaturizing the disc (D) or adjusting the curvature (R) to be gentle.

[0217] The ultimate goal of this design optimization is to ensure the 'same level of operational safety margin' even in harsh piping environments with different strain rates and inner diameter dimensions.

[0218] Consequently, the present invention ensures that the valve's anti-seizing performance remains consistent and does not deteriorate even when the piping material is changed from PE to PVC or vice versa. This demonstrates the unique technical flexibility and compatibility that allow designers to confidently adopt the valve of the present invention regardless of the piping material at the site.

[0220] FIG. 11 is a cross-sectional view of a key part showing the mechanical coupling structure of a valve body (100) and a seat (110) according to another embodiment of the present invention.

[0221] Referring to FIG. 11, the seat (110) according to the present invention is mechanically coupled to an uneven or undercut structure provided on the inner diameter surface of the valve body (100). Specifically, a curved portion protruding or recessed in the radial or axial direction is formed on the inner diameter side of the valve body (100), and the seat (110) can be designed to engage shape-adaptively with said curved portion.

[0222] This combined structure provides the following technical advantages.

[0223] First, the bonding rigidity is maximized. Despite the shear stress generated during the process of high-velocity fluid passing through or the disc (200) repeatedly opening and closing, the aforementioned uneven structure physically prevents the seat (110) from being pushed out or detached from the valve body (100). In particular, when applying an insert molding method in which the seat is integrally molded into the body, the curved portion widens the bonding area between the seat material and the body and strengthens mechanical restraint, thereby increasing watertight reliability.

[0224] Second, ease of maintenance is ensured. The uneven structure of the present invention provides an interface that allows the seat (110) to be forcibly separated from and reattached to the valve body (100) as needed. This enables the seat to be selectively detached and replaced without the need to replace the entire valve body in the event of wear or damage to the seat, thereby creating an economic effect of reducing maintenance costs and extending the service life of the product.

[0226] FIG. 12 is an exploded perspective view showing the stem support and sealing structure of a pipe interference prevention type butterfly valve (1) according to another embodiment of the present invention.

[0227] Stem leakage in a butterfly valve (1) refers to the phenomenon in which internal fluid leaks out through a small gap between the stem receiving portion at the top of the valve body (100) and the rotating stem (250). This is mainly caused by mechanical wear of the sealing member due to the repeated opening and closing operation of the valve, deformation of the seal due to the high pressure of the fluid, and eccentric load applied to the stem due to pipe deformation.

[0228] In particular, in high-pressure and high-speed flow environments, as the pressure acting as the stem support increases, a critical point is reached where the sealing performance rapidly deteriorates.

[0229] Referring to FIG. 12, the stem leakage prevention structure according to the present invention is provided by stacking in multiple stages within a stem receiving space formed on the upper part of a valve body (100).

[0230] On the upper part of the stem (250) that transmits rotational force to the disk (200), a stem seal (210), a stem bushing (212), a split ring (214), a thrust washer (216), and a retaining ring (218) are sequentially stacked and combined from the bottom part to the top part.

[0231] The stem seal (210) blocks primary leakage to the outside in response to the internal pressure of the fluid. In particular, the present invention is characterized by maximizing the reliability of leakage prevention even under extreme operating conditions by additionally arranging a separate sealing member, described later, in addition to the stem seal (210) to create a redundant sealing structure.

[0232] That is, the stem seal (210) is made of a material such as BUNA-N, which has excellent oil resistance and elasticity, and maintains primary airtightness at the lower part of the stem (250). Additionally, through the duplication of the stem sealing, a double defense system can be established to completely block fluid from the upper structure and prevent external leakage even in the event of wear of the primary seal or micro-leakage caused by high pressure.

[0233] The stem bushing (212) precisely guides the rotation axis between the outer diameter of the stem (250) and the valve body housing. This absorbs the lateral load generated during the rotation of the stem to prevent eccentricity and vibration of the stem, and helps maintain airtightness performance for a long period by dispersing the uneven stress applied to the sealing parts.

[0234] The stem bushing (212) is made of a self-lubricating material such as acetal, and by precisely maintaining the rotational center of the stem (250), it suppresses the occurrence of a gap between the seal and the stem due to vibration or eccentricity of the stem, thereby eliminating the root cause of leakage.

[0235] The split ring (214) and the thrust washer (216) firmly support the thrust load that causes the stem (250) to protrude upward due to fluid pressure. In particular, the split ring (214) is seated in the circumferential groove of the stem to distribute the vertical load, and the thrust washer (216) reduces friction between parts and ensures mechanical stability based on its pressure resistance.

[0236] The retaining ring (218) positions all the stacked parts at the top and finally restrains them inside the valve body. This stacked coupling structure acts as a physical lock to prevent the sealing and support parts from moving out of position even in a high-pressure environment, thereby ensuring the integrity of the entire system.

[0237] The split ring (214) and thrust washer (216) firmly support the thrust load that causes the stem to spring upward due to fluid pressure, based on the excellent pressure resistance of the brass material.

[0238] The retaining ring (218) is made of 304SS material and finally restrains all these parts so that they do not detach even in a high-pressure environment.

[0239] 304SS is a representative austenitic stainless steel with a chemical composition containing approximately 18% chromium (Cr) and 8% nickel (Ni). This composition forms a robust passive film on the metal surface, providing excellent corrosion resistance that effectively inhibits oxidation and corrosion. In addition, it possesses the characteristic of maintaining stable mechanical properties over a wide temperature range from cryogenic to high temperatures.

[0240] The technical background for applying 304SS material to the retaining ring (218), etc., located at the top of the stem support of the present invention is as follows.

[0241] Industrial sites where valves are installed are at high risk of exposure to moisture or various chemicals. 304SS has strong resistance to atmospheric corrosion and chemical corrosion that may occur due to fluid leakage, preventing physical damage to the retaining ring, which is the outermost fixing part, and maintaining a stable restraint state for a long period.

[0242] Sufficient yield strength and tensile strength are required to firmly support the upward thrust transmitted from the multiple sealing parts and split ring (214) accumulated inside the stem support structure. The 304SS material provides excellent rigidity against such mechanical stress, thereby serving to firmly lock the entire laminated structure without deformation or detachment of the ring even in a high-pressure environment.

[0243] Since the retaining ring (218) must be precisely fitted into the groove of the valve body (100), fine dimensional tolerance control is essential. The 304SS material has excellent machinability and formability, enabling precise dimensional realization, which ensures a gap-free assembly between parts, thereby suppressing stem vibration and providing an indirect effect of assisting sealing performance.

[0244] As illustrated in FIG. 12, the stem support portion supporting the stem (250) provides a precision receiving space in which a stem seal (210), bushing (212), split ring (214), retaining ring (218), etc., which are stem leakage prevention structures are stacked and seated.

[0245] That is, it becomes the base where the airtightness and rotational precision of the stem (250) are determined.

[0246] A standardized flange surface (ISO 5211 standard, etc.) is formed on the upper part of the valve body (100), serving as a support surface for securely mounting a gearbox or an electric / pneumatic actuator. ISO 5211 is a standard for the dimensions, torque, and stem coupling of mounting flanges connecting industrial valves and partial rotary actuators (pneumatic, electric, etc.). It is a key international standard that specifies flange sizes from F03 to F60 to ensure interchangeability and connection compatibility between valves and actuators from different manufacturers.

[0247] The strong rotational torque and repulsive force due to fluid pressure transmitted from the valve drive device to the stem (250) are absorbed and distributed to the main body. In particular, the upper body of the 1PC structure has no joints, so it has high resistance to twisting or fatigue failure even during high-torque operation.

[0249] FIG. 13 is a cross-sectional perspective view and an enlarged view showing the upper and lower arrangement structure of a stem bearing (300) according to one embodiment of the present invention.

[0250] Referring to FIG. 13, the upper and lower portions of the stem (250) according to the present invention are each provided with a stem bearing (300) to smoothly support the rotational drive of the stem and maintain axial alignment.

[0251] By adopting a two-end support method in which stem bearings (300) are placed at the upper and lower ends of the stem (250), the bending moment generated in the stem (250) when fluid pressure is applied to the disk (200) is effectively dispersed.

[0252] This prevents slight bending of the stem (250), thereby providing mechanical stability so that the sealing parts of the stem leakage prevention structure described above can maintain a uniform compression force without uneven wear.

[0253] Meanwhile, the stem bearing (300) is made of a material with excellent self-lubricating properties or a low-friction metal material, which can minimize frictional resistance when the stem (250) rotates. This enables smooth rotation even under high lateral loads applied to the disc, especially in large-diameter valves of 350A or larger, and creates synergy with the aforementioned gear ratio upward design and VR machining structure to drastically reduce the overall operating torque.

[0254] As illustrated in FIG. 13, a lower support housing (270) may be integrally formed protruding from the lowest part of the valve body (100) according to the present invention to receive and precisely support the lower end of the stem (250).

[0255] A hollow receiving space is formed on the inner side of the lower support housing (270) to which the end of the stem (250) can be inserted, and a stem bearing (300) is seated within this space. This is to mechanically guide the stem (250) so that it can rotate while maintaining vertical alignment at the center of the flow path, symmetrical with the upper body.

[0256] This structure absorbs the bending load and shear stress concentrated at the bottom of the stem (250) when fluid pressure is applied to the disc (200) and distributes them throughout the body. In particular, the bottom support housing (270) is designed to locally reinforce the thickness of the corresponding area, thereby serving as a support base that suppresses deformation of the valve body (100) even in a high-pressure environment and ensures stable operation of the stem (250).

[0257] Additionally, the lower support housing (270) serves as a base that supports the weight of the disc (200) and the stem (250) in the vertical direction. This prevents the disc (200) from sagging downward, thereby maintaining a constant concentricity between the outer diameter of the disc and the seat (110) and ensuring long-term airtightness reliability of the valve. Explanation of the symbols

[0259] 1: Pipe interference prevention butterfly valve 10: Piping 100: Valve body 110: Sheet 200: Disk 250: Stem 300: Stem bearing

Claims

Claim 1 A butterfly valve installed in a pipe to control the flow of fluid comprises: a valve body having a fluid passage formed in the center; a disc rotatably installed within the fluid passage of the valve body; a seat disposed between the valve body and the disc to maintain airtightness; and a stem connected to the disc to transmit rotational force; wherein the disc is formed with a VR machining structure having a predetermined curvature (R) at the edge and forming a radial clearance defined as the shortest distance between the inner diameter surface of the pipe and the edge of the disc, wherein the radial clearance is formed to be greater than the thickness of the seat when the disc is fully open due to the VR machining structure, and the seat is formed with a diagonal structure in which both sides of the inner diameter surface of the seat gradually taper toward the center to minimize the surface contact area when in contact with the VR machining surface formed by the curvature buffering shape of the VR machining structure, and wherein the VR machining structure is variably designed to correspond to changes in the effective inner diameter (A) of the stub end according to the material of the pipe; and the clearance when applying a PE pipe of a flexible material ( ) and clearance when applying rigid PVC piping ( The ratio of ) A pipe interference prevention butterfly valve characterized by the outer diameter (D) and curvature (R) of the disk being adjusted so that the range of ) is maintained between 0.8 and 1.2, thereby ensuring the same level of operational safety margin even in piping environments having different strain and inner diameter dimensions. Claim 2 A pipe interference prevention butterfly valve according to claim 1, wherein the curvature (R) of the VR processing structure is formed to have a range of 0.5T to 1.5T relative to the maximum thickness (T) of the disk; the outer diameter (D) of the disk is formed to have a diameter reduced by 5% to 12% relative to the effective inner diameter (A) of the stub end; and the radial clearance (C) is formed by the difference between the effective inner diameter (A) of the stub end and the outer diameter (D) of the disk, and is formed to a size of 1.2 to 2.0 times the thickness of the seat, thereby maintaining airtightness through elastic compression of the seat even in the case of elliptical deformation of the pipe and simultaneously ensuring an interference-free rotational trajectory of the disk. Claim 3 delete Claim 4 A pipe interference prevention butterfly valve according to claim 1, wherein the stem is made of a precipitation-hardened stainless steel material and comprises, in weight percent, chromium (Cr): 15.0 ~ 17.5%, nickel (Ni): 3.0 ~ 5.0%, copper (Cu): 3.0 ~ 5.0%, and the remainder is iron (Fe) and other unavoidable impurities, characterized in that torsional deformation of the stem is suppressed even under eccentric load caused by deformation of the pipe. Claim 5 A butterfly valve that prevents pipe interference according to claim 1 or 4, wherein a stem seal, a stem bushing, a split ring, a thrust washer, and a retaining ring are sequentially laminated and combined on the upper part of the stem from the lower part in the direction of the upper part; wherein a stem bearing supporting the rotational drive of the stem is provided on the upper part and the lower part of the stem, respectively, and a lower support housing accommodating the lower end of the stem and the stem bearing is integrally formed on the lowest part of the valve body to support the stem at both ends.

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