A double-end-face split mechanical seal

Abstract

This invention relates to the field of mechanical seal technology, specifically to a double-end-face split mechanical seal, comprising a split upper flange, a lower flange, an intermediate shell, a transmission seat, a medium moving ring, a medium stationary ring, an atmospheric moving ring, and an atmospheric stationary ring. The transmission seat is fixed on a rotating shaft, and the intermediate shell is sleeved on the outside of the transmission seat. The upper and lower flanges are respectively connected to both ends of the intermediate shell. The atmospheric stationary ring is installed with the upper flange, and the medium stationary ring is installed with the lower flange. The medium moving ring and the atmospheric moving ring are axially connected to both sides of the transmission seat, and a space is left between them to accommodate an elastic element to provide axial clamping force for the moving ring, pushing the moving ring to fit against the end face of the corresponding stationary ring to form a double-end-face sealing pair. The intermediate shell, upper flange, lower flange, and double-end-face sealing pair together form a sealing cavity. At least one of the intermediate shell, upper flange, and lower flange has a fluid interface communicating with the sealing cavity. This mechanical seal has a simple structure and is easy to install.

Description

Technical Field

[0001] This invention relates to the field of mechanical seal technology, and specifically to a double-end-face split mechanical seal. Background Technology

[0002] Mechanical seals are key dynamic sealing components in rotating equipment (such as reactors, agitators, centrifugal pumps, etc.), and their performance directly affects the safety and stability of equipment operation. In the fields of chemical, pharmaceutical, and metallurgical industries, equipment often needs to handle toxic, flammable, and highly corrosive media, or operate under harsh conditions such as high temperature and high pressure, requiring extremely high reliability of the seals.

[0003] While traditional integral mechanical seals offer excellent performance, their installation and maintenance require extensive disassembly of spindle-related components, leading to long equipment downtime and high maintenance costs. To address this technical problem, split mechanical seals have emerged. These seals feature a separable core component, allowing for assembly and disassembly without removing the spindle and related components, significantly improving maintenance efficiency.

[0004] Currently, most split mechanical seals on the market have a single-end-face structure (such as the fully split reactor shaft seal device disclosed in Chinese patent CN112128377A, which sets the stationary ring, rotating ring, spring seat, and transmission seat as a split structure). While this solves the problem of convenient installation, it places the system safety entirely on a single sealing end face, resulting in an inherent lack of safety redundancy. Once this single sealing end face fails, the medium will be directly discharged, failing to meet the sealing requirements of high-risk media.

[0005] To enhance safety, the industry has attempted to develop split-face seals with double end faces. For example, Chinese patent CN112178195B discloses a cartridge-type axial split-face mechanical seal, which creates safety redundancy by splitting all components and setting two sealing end faces. However, to achieve the double-end face function on the split structure, such solutions have to introduce complex linkage mechanisms and multiple drive components, resulting in a large number of parts, stringent assembly precision requirements, and extremely high manufacturing costs. This structural complexity weakens the core advantage of split-face seals: ease of on-site maintenance. Summary of the Invention

[0006] This invention provides a double-end-face split mechanical seal to solve the technical problems of complex structure and inconvenient installation and maintenance of existing double-end-face split seals.

[0007] To solve the above problems, the present invention provides a double-end-face split mechanical seal, which adopts the following technical solution:

[0008] A double-end split mechanical seal, for mounting on a rotating shaft, includes a split upper flange, a lower flange, an intermediate housing, a transmission seat, a medium dynamic ring, a medium stationary ring, an atmospheric dynamic ring, an atmospheric stationary ring, and a detachable mounting block; the transmission seat is fixed to the rotating shaft, the intermediate housing is mounted on the outside of the transmission seat, and the upper and lower flanges are respectively connected to the axial ends of the intermediate housing; the medium stationary ring is mounted to the lower flange, and the atmospheric stationary ring is mounted to the upper flange;

[0009] The medium dynamic ring and the atmospheric dynamic ring are located on both sides of the transmission seat along the axial direction and are connected to the transmission seat to form an integrated synchronous rotation module;

[0010] A first accommodating space is provided between the transmission seat and the medium moving ring, and a second accommodating space is provided between the transmission seat and the atmospheric moving ring; a first elastic element is provided in the first accommodating space to provide axial clamping force to the medium moving ring, pushing the medium moving ring to fit against the end face of the medium stationary ring to form a medium-side sealing pair; a second elastic element is provided in the second accommodating space to provide axial clamping force to the atmospheric moving ring, pushing the atmospheric moving ring to fit against the end face of the atmospheric stationary ring to form an atmospheric-side sealing pair;

[0011] The intermediate shell, upper flange, lower flange, medium static ring, and atmospheric static ring together form a sealed cavity; at least one of the intermediate shell, upper flange, and lower flange has a fluid interface communicating with the sealed cavity.

[0012] The mounting block is installed in the first and second accommodating spaces during transportation and storage to limit the axial displacement of the moving ring relative to the transmission seat and maintain the pre-compression state of the first and second elastic elements.

[0013] This invention employs a dual sealing pair setup on both the medium side and the atmospheric side, forming a closed sealing cavity between the two sealing pairs, thus constructing multiple safety barriers.

[0014] The core components of this mechanical seal, such as the upper flange, lower flange, intermediate housing, transmission seat, and sealing ring, all adopt a split structure. They can be opened axially or radially and fitted onto the rotating shaft without disassembling related components such as bearings, couplings, reducers, or motors. During on-site installation, replacement, or maintenance, only the flange connecting bolts need to be loosened to complete the overall disassembly and assembly, shortening the installation and maintenance cycle. It is particularly suitable for large reaction vessels, agitators, and other space-constrained or continuous production scenarios.

[0015] Both the medium-driven rotating ring and the atmospheric rotating ring are directly mounted on both axial sides of the transmission seat and connected to it for transmission, thus forming an integrated synchronous rotating module. This design, on the one hand, facilitates on-site installation and maintenance through its modular structure; on the other hand, it simplifies the complex drive mechanism of traditional double-end mechanical seals, avoiding the lag, slippage, or uneven wear problems caused by multi-stage transmissions or floating structures in traditional designs. Simultaneously, it simplifies the power transmission path, improves the concentricity and stability of the rotating rings, reduces end-face wear, and extends seal life.

[0016] The fluid interface on the sealed cavity facilitates the connection of external sealing fluid or inert buffer gas. Furthermore, the flexible location of the fluid interface allows for easy on-site piping layout.

[0017] Elastic components such as helical springs may experience stress relaxation, plastic deformation, or preload decay under prolonged unrestrained conditions, especially in high-temperature storage or long-distance transportation vibration environments. The mounting block, through mechanical limiting, ensures that the spring is always in a preloaded state, preventing insufficient elastic force from causing insufficient sealing force at the sealing end face during the initial start-up of the equipment, thereby eliminating the risk of dry start leakage.

[0018] During on-site installation, users only need to remove the mounting clips according to the procedure, and the elastic element will immediately release the preload, pushing the moving ring to automatically engage with the stationary ring, without the need for additional spring preload adjustments or complex initial alignment operations. This "plug and play" feature significantly reduces the skill requirements for installers, shortens commissioning time, and ensures consistent sealing performance after each installation.

[0019] As a preferred embodiment of the present invention, the mating surfaces of all split components adopt a stepped or V-shaped interface. Preferably, all split components are supplemented with a high-strength locking structure on the mating surfaces to ensure the integrity of the whole after closure.

[0020] As a preferred embodiment of the present invention, the intermediate housing is provided with a fluid interface communicating with the sealed cavity, for introducing and / or discharging fluid into the sealed cavity.

[0021] In a preferred embodiment of the present invention, the fluid interface is connected to a sealing fluid system, which fills the sealing cavity with a sealing fluid at a pressure higher than that of the sealed medium, thereby lubricating, cooling, and isolating the end faces of the medium-side sealing pair and the atmospheric-side sealing pair. This sealing cavity not only serves as a safety barrier but also allows for proactive control of the internal pressure to be slightly higher than the medium-side pressure, achieving "zero leakage" or even "zero escaping" operation.

[0022] Because the sealing fluid pressure is higher than the medium pressure, even if a minor leak occurs in the sealing pair on the medium side, the leak will flow unidirectionally from the sealing cavity to the process medium cavity, rather than the hazardous medium leaking out to the sealing cavity side. This fundamentally eliminates the risk of toxic, flammable, highly corrosive, or high-purity media leaking into the environment, making it particularly suitable for industries such as petrochemicals, pharmaceuticals, and semiconductors, which have zero tolerance for environmental protection and safety issues.

[0023] A constant sealing fluid pressure that is slightly higher than the medium pressure can offset the effect of process medium side pressure fluctuations on the sealing pair, making the dynamic ring more uniformly stressed, reducing end face separation or chatter caused by pressure transients, thereby reducing leakage rate and improving dynamic stability. It is especially suitable for pumping systems with frequent pressure changes or pulsations.

[0024] The sealing fluid (usually a clean, low-viscosity, high-thermal-stability special sealing fluid, such as white oil, silicone oil, or deionized water) circulates within the sealing cavity to lubricate, cool, and clean the end faces of the two sets of sealing pairs: the medium dynamic ring / stationary ring and the atmospheric dynamic ring / stationary ring (flushing away tiny particles that may enter the end faces to prevent abrasive wear).

[0025] In a preferred embodiment of the present invention, both the first and second elastic elements are helical springs uniformly arranged along the circumference. The symmetrical and equally spaced arrangement of the helical springs along the circumference of the transmission seat ensures that the axial thrust experienced by the medium-driven rotating ring and the atmospheric rotating ring is highly consistent at all points on the circumference. This arrangement effectively avoids rotating ring tilting, end-face warping, or uneven wear caused by uneven local force distribution, ensuring that the sealing pair remains parallel and in contact throughout operation, reducing leakage rate and extending end-face service life.

[0026] As a preferred embodiment of the present invention, the medium stationary ring and / or atmospheric stationary ring are made of dry-friction-resistant graphite impregnated with a solid lubricant, enabling the mechanical seal to operate under dry-friction conditions without external fluid injection. In the event of unexpected failure of the sealing fluid system (such as pump failure, pipeline blockage, or pressure loss) or during the brief period before a stable sealing fluid circulation is established during start-up or shutdown, traditional mechanical seals are prone to dry friction due to lack of lubrication on the end faces, leading to a sudden temperature rise, thermal cracking of the end faces, and even catastrophic failure. The present invention, by employing a dry-friction-resistant stationary ring material, enables the sealing pair to have reliable dry-running capability, avoids instantaneous leakage of hazardous media, and improves the safety redundancy of the system under abnormal operating conditions.

[0027] For some low-risk, intermittently operating, or space-constrained equipment (such as small reaction vessels, mobile dosing devices, laboratory stirrers, etc.), the external sealing system can be completely eliminated, and basic sealing functions can be achieved solely by relying on dry-wear resistant sealing pairs.

[0028] During planned maintenance or temporary shutdowns, if short-term evacuation of the sealing fluid or isolation of the auxiliary system is required, traditional seals must be shut down immediately to prevent damage. However, the dry-wear resistant design of this invention allows the equipment to operate at low speed or be manually rotated for short periods without sealing fluid, facilitating process evacuation, shaft inspection, or alignment adjustments, thus improving the flexibility and safety of on-site operations.

[0029] Dry-wear resistant stationary rings can form excellent tribological pairings with conventional rotating ring materials (such as silicon carbide): in a wet state, the SiC / graphite combination exhibits a low coefficient of friction and high thermal conductivity; in a dry state, the self-lubricating properties of graphite effectively suppress temperature rise and adhesive wear. By selecting suitable materials, a "dual-purpose material, excellent performance in both dry and wet conditions" can be achieved, avoiding the need to develop complex structures separately for dry operation or sacrifice performance under normal operating conditions.

[0030] As a preferred embodiment of the present invention, positioning steps are provided on both sides of the transmission seat, and positioning grooves are provided on the medium moving ring and the atmospheric moving ring to assemble with the positioning steps. The cooperation between the positioning steps and the positioning grooves not only achieves axial positioning, but also provides radial guidance, ensuring that the moving rings maintain good coaxiality during high-speed rotation and effectively suppressing end face wobble caused by installation deviation or thermal deformation.

[0031] As a preferred embodiment of the present invention, the medium dynamic ring and the atmospheric dynamic ring are connected to the transmission seat through at least one transmission component to achieve integrated synchronous rotation drive (i.e., torque transmission).

[0032] Since the torque is borne by the transmission components rather than relying on the shear strength of the rotating ring itself, the rotating ring can preferentially use advanced sealing materials with high wear resistance, low friction, but also high brittleness (such as reaction-bonded silicon carbide, zirconia ceramics, etc.) without worrying about breakage or deformation during transmission. This functional separation design optimizes material matching, balancing sealing performance and mechanical strength.

[0033] If the rotating ring is directly driven via interference fit or end-face friction, additional radial stress or uneven load can easily be generated on the end face, affecting the uniformity of the seal. However, by using an independent transmission component, the torque transmission path is completely decoupled from the sealing end face. The axial clamping force is only used to maintain the end-face fit, and the two functions do not interfere with each other, thus ensuring that the sealing pair operates under pure axial load, improving seal stability and lifespan. As a critical load-bearing component, the transmission component often wears or shears before the sealing end face fails. Preferably, a visual observation window or vibration sensor can be installed near the transmission component to indirectly assess the seal health by monitoring the transmission status, providing a basis for predictive maintenance.

[0034] In a preferred embodiment of the present invention, the transmission component includes a pin disposed on the transmission seat, and a medium moving ring seat and an atmospheric moving ring seat respectively cooperating with the pin. The medium moving ring is disposed on the medium moving ring seat, and the atmospheric moving ring is disposed on the atmospheric moving ring seat. The medium moving ring seat and the atmospheric moving ring seat are connected to the transmission seat via the pin.

[0035] The transmission function is carried out by an independent rotating ring seat. The pin transmits the rotational torque from the transmission seat to the medium rotating ring seat and the atmospheric rotating ring seat in sequence, and then the rotating ring seat drives the rotating ring to rotate synchronously. This configuration prevents the rotating ring body from directly participating in the force transmission, avoiding the risk of cracking of brittle sealing materials (such as silicon carbide and ceramics) due to shear or impact loads, and improving the structural safety and service life of the sealing assembly.

[0036] The rotating ring seat can be made of high-strength stainless steel or corrosion-resistant alloy, while the rotating ring can be freely selected from advanced sealing materials with high hardness and low coefficient of friction (such as SiC / SiC, SiC / graphite, etc.). This "functional separation and material optimization" setting maximizes the wear resistance and chemical stability of the sealing end face while ensuring transmission strength, meeting the requirements of extreme working conditions.

[0037] In a preferred embodiment of the present invention, an isolation seal is provided between the inner wall of the positioning groove and the outer wall of the rotating shaft to prevent the medium from entering the first accommodating space and the second accommodating space. Preferably, the isolation seal is an O-ring.

[0038] This isolation seal forms a secondary sealing barrier independent of the main sealing pair, and has the following functions: First, it prevents the process medium from seeping into the first and second accommodating spaces axially; second, it prevents corrosive, high-viscosity, or particulate media from contacting the elastic elements such as the helical spring, preventing them from rusting, jamming, or losing elasticity; third, it ensures that the elastic elements are kept in a clean, dry, or inert environment for a long time, ensuring a stable output of axial clamping force.

[0039] Even in the extreme case of complete failure of the sealing fluid system, the dry-running stationary ring can maintain short-term or intermittent sealing function, while the isolation seal continuously protects the elastic element. Their synergistic effect gives the sealing system a graded failure response capability: the primary sealing pair first bears the dry-running load, and then the secondary isolation barrier protects the core drive, buying valuable downtime for operators and preventing catastrophic leaks.

[0040] As a preferred embodiment of the present invention, the mounting block is U-shaped.

[0041] Mounting clips are typically small metal or high-strength engineering plastic parts that can be quickly installed and removed using clips, screws, or pins without the need for special tools. They do not affect the main sealing structure, nor do they participate in the sealing or transmission functions during operation. They are typical "disposable auxiliary tooling" that combines economy and practicality.

[0042] The beneficial effects are:

[0043] 1. This invention integrates the moving rings on the medium side and the atmospheric side onto a single drive seat, forming an "integrated synchronous rotating module." Although it employs a high-performance double-end-face design, its highly integrated and simplified structure does not significantly increase the difficulty of machining, aligning, and assembling the core split components on-site, thus perfectly preserving and inheriting the fundamental advantage of split seals: "easy installation and maintenance." By synchronously driving the moving rings on both sides through a single drive seat, the complex mechanism common in traditional double-end-face mechanical seals, which requires an independent drive unit for each end face, is completely eliminated. This not only reduces the number of parts and manufacturing costs but also eliminates the potential failure risks caused by multi-stage transmission and floating structures. The simplified power chain and integrated modular structure reduce cumulative assembly errors, improve transmission accuracy and operational stability, and ensure that the mechanical seal has a longer sealing service life and higher operational reliability.

[0044] 2. This invention employs a dual sealing system on both the medium and atmospheric sides, forming a closed sealing cavity between the two sealing surfaces, thus constructing multiple safety barriers. Even if a single sealing surface fails, the leaked medium is completely confined within the sealing cavity. Furthermore, by controlling the pressure of the sealing liquid system, the direction of medium leakage can be actively controlled, fundamentally eliminating the risk of dangerous media leakage. This achieves "zero escape" sealing for toxic, harmful, and flammable media, improving the safety of equipment operation.

[0045] 3. This invention, by setting up a sealing cavity that communicates with an external sealing fluid system and matching it with a dry-wear resistant stationary ring material, allows the same sealing product to flexibly select between "dry-wear mode" or "isolation lubrication mode" operation according to actual working conditions. This setting breaks through the limitation of poor adaptability of traditional split seals, enabling them to cope with harsh conditions from ordinary working conditions to high temperature and high-risk media, greatly expanding the application scenarios of split seals.

[0046] 4. This invention employs a precision-machined stepped or V-shaped split interface, coupled with a high-strength locking structure, ensuring the integrity and dynamic operational stability of the split components after assembly. This design enables the split seal to achieve rigidity comparable to that of a monolithic seal, guaranteeing uniform contact and reliable transmission at the sealing end faces, fundamentally solving the technical problems of insufficient rigidity and easy leakage in traditional split seals.

[0047] 5. In this invention, the torque is borne by the transmission component, and the moving ring body does not directly participate in the force transmission. This avoids the risk of cracking of brittle moving ring sealing materials (such as silicon carbide and ceramics) due to shear or impact loads, and improves the structural safety and service life of the sealing assembly.

[0048] 6. This invention, by setting an isolation seal between the moving ring and the rotating shaft, completely isolates the drive and compensation mechanism from the process medium, effectively preventing the elastic element from failing due to corrosion, blockage, or crystallization. This improves the long-term operational reliability of the seal in harsh media environments and extends its service life.

[0049] 7. The installation of the locking blocks ensures that the rotating ring, transmission seat, and elastic element are delivered as a stable rotating module, facilitating on-site installation and commissioning. Even after multiple opening and closing tests or long-distance transportation, the relative positions of each component remain precise, preventing assembly failure due to misalignment of the elastic element or displacement of the rotating ring during on-site assembly. Attached Figure Description

[0050] Figure 1 This is a cross-sectional view of a double-end-face split mechanical seal according to the present invention.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1. Upper flange; 2. Lower flange; 3. Intermediate shell; 4. Transmission seat; 41. Pin; 42. Helical spring; 5. Medium moving ring; 51. Medium moving ring seat; 6. Medium stationary ring; 61. Medium stationary ring seat; 7. Atmospheric moving ring; 71. Atmospheric moving ring seat; 8. Atmospheric stationary ring; 81. Atmospheric stationary ring seat; 9. Sealing cavity; 91. Sealing ring; 92. Isolation seal; 10. Mounting block. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0054] In the description of this application, it should be noted that, unless otherwise stated, "multiple" means two or more; the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as a limitation of this application.

[0055] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more.

[0056] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "setup," "equipped with," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0057] Existing split-face mechanical seals often require complex linkage mechanisms, multiple elastic elements, and precision alignment structures to ensure synchronous contact and pressure balance of the two sets of split rings under dynamic operating conditions. This leads to a dramatic increase in the number of parts, extremely high assembly precision requirements, and a significant rise in manufacturing costs. This structural complexity not only weakens the core advantage of split seals—"easy on-site maintenance"—but can also cause problems such as intersecting leakage paths, stress concentration, or movement stagnation due to poor fit of the split surfaces, ultimately reducing overall reliability. For example, Chinese patent CN112178195B.

[0058] This invention abandons the complex approach common in traditional double-end face seals, which involves setting up a separate spring drive unit (such as two independent push rings, multiple sets of springs, and drive screws) for each end face. Instead, it creatively employs a rotating drive seat, connecting the two moving rings to the drive seat via a moving ring seat to form a single rotating module. This design significantly simplifies the complex drive mechanism of traditional double-end face mechanical seals, reduces the number of parts, lowers manufacturing costs, and reduces potential failure points from the outset, thus improving the overall reliability of the seal. Furthermore, due to the simplified structure, the processing, alignment, and assembly difficulty of the split components of this double-end face seal are not increased, perfectly preserving the core advantage of split seals—ease of installation and maintenance.

[0059] like Figure 1 The mechanical seal shown is a double-end-face split mechanical seal, coaxially mounted on the rotating shaft of equipment (such as a reactor). The mechanical seal includes a split upper flange 1, an intermediate shell 3, a lower flange 2, a transmission seat 4, a medium moving ring seat 51, an atmospheric moving ring seat 71, a medium stationary ring seat 61, an atmospheric stationary ring seat 81, and corresponding sealing rings. All of the above components adopt a split structure that is split along the axis.

[0060] To achieve high reliability in the split structure, all split mating surfaces utilize precision-machined stepped or V-shaped interfaces. During assembly, the mating surfaces of the interfaces naturally guide and align, enabling rapid and precise closure of the split sections, effectively reducing installation difficulty and alignment errors. Simultaneously, the structure's complex geometry forces any medium attempting to cross the split surfaces to undergo multiple abrupt changes in direction and cross-section, generating significant flow resistance and pressure drop, forming a highly efficient "labyrinthine" sealing barrier. Structurally, this significantly enhances the static sealing capability of the split surfaces, providing primary assurance for the overall seal reliability.

[0061] To ensure the assembled components possess sufficient integrity to withstand internal pressure and dynamic loads, a high-strength locking structure is added to the mating surface. This locking structure can be a combination of locating pins and fastening screws, or a split-type collar and locking bolt fitted onto the outside of the components.

[0062] The aforementioned "interface + locking structure" design allows the disassembled components to be reassembled into a functional unit with extremely high rigidity, integrity, and sealing. This unit effectively resists internal fluid pressure and operational vibrations, fundamentally preventing leakage from the disassembled surface, thus achieving the same reliability standards as an integral seal in key mechanical performance aspects.

[0063] During on-site installation, operators simply need to fit each half of the split component onto the rotating shaft and place it in its corresponding position within the equipment cavity, then assemble them. After assembly, the components are naturally guided and automatically aligned using precision-machined interfaces on the split surfaces (such as stepped or V-shaped interfaces), achieving accurate positioning. Then, tightening the locking mechanisms (such as locating pins, fastening screws, or clamps) connects the split components into a single functional unit with high rigidity and integrity. This setup greatly simplifies installation and maintenance, reduces reliance on operator skills, and shortens equipment downtime.

[0064] The split transmission seat 4 is fixed to the rotating shaft by a locking device and rotates together with the shaft.

[0065] In this preferred embodiment, the cross-section of the transmission seat 4 is U-shaped, thus forming an annular groove in its circumference. The locking device consists of multiple sets of set screws evenly distributed along the circumference of the annular groove. Each set of set screws includes a set screw and a mating set block, which has a split structure. The transmission seat 4 is fixed to the rotating shaft by the set screws and set blocks, resulting in a compact structure and convenient operation, suitable for rapid on-site installation and maintenance of split structures. The evenly distributed locking points (i.e., the set screw sets) provide uniform and stable radial locking force, effectively preventing relative rotation or axial movement between the transmission seat 4 and the rotating shaft, ensuring the accuracy and reliability of torque transmission.

[0066] During assembly, the set block is placed in the "U"-shaped groove, and then the set screw is tightened. The axial thrust of the set screw is converted into a radial clamping force on the surface of the rotating shaft through the set block, so as to achieve a firm connection and circumferential fixation between the transmission seat 4 and the rotating shaft.

[0067] It is understood that in other embodiments not shown, the locking device may be replaced with other forms known to those skilled in the art, such as a split clamping ring, which can also achieve the purpose of fixing the transmission seat 4 to the rotating shaft.

[0068] The split intermediate housing 3 is fitted onto the outside of the transmission base 4. The split upper flange 1 and lower flange 2 are fixedly connected to the axial ends of the intermediate housing 3 by screws. In this embodiment, the upper flange 1, lower flange 2 and intermediate housing 3 are connected through the same long screw, which greatly simplifies the assembly process and ensures the alignment between components.

[0069] The split-type medium stationary ring 6 and atmospheric stationary ring 8 are installed using independent medium stationary ring seats 61 and 81, respectively. Specifically, the medium stationary ring seat 61 is positioned and installed on the lower flange 2 via the stepped structure of the lower flange 2, and the atmospheric stationary ring seat 81 is positioned and installed on the upper flange 1 via the stepped structure of the upper flange 1, and both are secured with circumferentially distributed bolts. The medium stationary ring 6 and atmospheric stationary ring 8 are then embedded and fixed in their respective stationary ring seats. In this example, the stationary ring seats are provided with stepped structures for precise positioning and installation of the corresponding stationary rings.

[0070] It is understood that the above structure can be simplified in other embodiments not shown. For example, the separate stationary ring seat can be omitted, and the stepped structure used for positioning and installing the stationary ring can be directly machined onto the upper flange 1 and the lower flange 2, thereby making the upper and lower flanges 2 function as stationary ring seats. This simplified solution can also achieve the positioning and fixing of the stationary ring and participate in the formation of the sealing cavity 9.

[0071] The medium moving ring 5 and the atmospheric moving ring 7 are located on both axial sides of the transmission seat 4 and are connected to the transmission seat 4 via a transmission component to rotate synchronously with it. The moving rings are directly connected to the transmission seat 4 to ensure synchronous rotation and reliable torque transmission. Specifically, the transmission component includes a pin 41 fixedly mounted on the transmission seat 4, and a medium moving ring seat 51 and an atmospheric moving ring seat 71 respectively cooperating with the pin 41. In this embodiment, the medium moving ring seat 51 and the atmospheric moving ring seat 71 are connected to the two axial ends of the transmission seat 4 via the same (or a group of symmetrically arranged) pin 41, thereby achieving integrated synchronous rotation drive. Since the medium moving ring seat 51 and the atmospheric moving ring seat 71 share the same (or a group of symmetrically arranged) pin 41, their angular positions with the transmission seat 4 are rigidly locked, ensuring that the two moving rings always maintain strict phase during rotation. This arrangement effectively prevents pressure disturbance, fluid disturbance, or vibration coupling in the sealing cavity 9 caused by small angular deviations between the moving rings, improving the dynamic stability of the system, and is especially suitable for high-speed or high-precision operating conditions.

[0072] The pin 41-moving ring seat structure is arranged axially, which does not occupy the radial space of the sealing cavity 9. This facilitates the formation of a uniform flow field of the sealing fluid within the sealing cavity 9, improving the cooling and lubrication efficiency of the two sets of sealing end faces. At the same time, the simple internal contour reduces fluid eddies and dead zones, lowering the risk of particle deposition.

[0073] The medium moving ring 5 and the atmospheric moving ring 7 are respectively fixedly installed on their corresponding moving ring seats. The medium moving ring seat 51 and the atmospheric moving ring seat 71 are provided with stepped structures for precise positioning and installation of the corresponding moving rings. Therefore, the transmission seat 4, the pin 41, the medium moving ring seat 51, the atmospheric moving ring seat 71, and the medium moving ring 5 and the atmospheric moving ring 7 together constitute a rigid, synchronously rotating functional unit—a rotating module.

[0074] The transmission base, rotating ring, and rotating ring base are designed with a modular and split structure, making on-site installation quick and simple, and significantly reducing maintenance downtime.

[0075] In mechanical seals, the transmission components that achieve "transmission connection" are diverse. In addition to the specific embodiments described above, it can also be achieved in other forms known to those skilled in the art, such as, but not limited to: spline connection, which transmits torque through the inner and outer splines set between the transmission seat 4 and the moving ring, and has a strong load-bearing capacity; and the form of torque transmission through the engagement of lugs and slots, which has a simple structure and no transmission clearance.

[0076] By directly coupling the rotating ring to the transmission seat 4 using rigid transmission components (such as transmission pins, splines, lugs, or slot structures), rotational torque can be effectively transmitted, avoiding the "lag" or "slippage" of the rotating ring caused by insufficient friction or excessive lubrication of the end face liquid film. Especially under start-up, frequency conversion, or high-viscosity media conditions, this rigid transmission component ensures that the sealing pair end face is always in a stable shear state, preventing dry friction or local overheating and improving sealing reliability.

[0077] The end faces of the medium dynamic ring 5 and the medium stationary ring 6 are fitted together to form a medium-side sealing pair for sealing the process medium. The end faces of the atmospheric dynamic ring 7 and the atmospheric stationary ring 8 are fitted together to form an atmospheric-side sealing pair, serving as a safety barrier facing the environment.

[0078] A first accommodating space is formed between the transmission seat 4 and the medium moving ring seat 51, and a second accommodating space is formed between the transmission seat 4 and the atmospheric moving ring seat 71. A first elastic element and a second elastic element are respectively disposed in the first and second accommodating spaces to provide continuous axial clamping force. This arrangement has a simple structure, and the axial clamping force of the two sealing pairs can be optimized separately: for example, the elastic forces on both sides can be adjusted differently according to the medium pressure, the isolation fluid pressure, or the operating conditions, avoiding the clamping force imbalance caused by sharing elastic elements, thereby ensuring that the two sealing end faces are always in the best contact state, extending service life and improving sealing stability. The first and second elastic elements push the medium moving ring 5 and the atmospheric moving ring 7 respectively through the corresponding moving ring seats, making them tightly fit against the corresponding stationary ring end faces, forming two reliable sealing end faces. This setup ensures the initial seal is established on the sealing face and automatically compensates for wear on the sealing face throughout its lifespan (when the sealing face wears due to normal operation, the spring automatically extends, pushing the moving ring to move axially, compensating for the wear gap in real time, ensuring that the two sealing faces remain tightly fitted throughout the entire lifespan, and maintaining stable sealing performance).

[0079] It is understood that in other embodiments, the rotating ring seat can also be omitted. In this case, the transmission seat 4 directly forms an accommodating space with the medium rotating ring 5 and the atmospheric rotating ring 7, and the elastic element acts directly on the rotating ring, which can also achieve the functions of torque transmission and wear compensation.

[0080] In this example, both the first and second elastic elements are composed of multiple cylindrical helical springs 42, which are evenly arranged along the circumference. This multi-spring arrangement provides uniform and stable end-face pressure. One end of each helical spring 42 abuts against the transmission seat 4, while the other end acts directly on the moving ring seat.

[0081] The helical spring 42 exhibits excellent linear stiffness and temperature stability, with minimal elastic decay even at high temperatures, maintaining stable end-face pressure over extended periods. As a standard component, the helical spring 42 can be made from corrosion-resistant and high-temperature-resistant alloy materials to meet the requirements of various media and temperatures. Its simple structure and low cost allow for partial replacement even if individual springs fail, without disassembling the entire seal, thus reducing maintenance costs.

[0082] The transmission seat 4 has a spring cavity to accommodate the helical spring 42. By directly machining the axially extending spring cavity into the body of the transmission seat 4, the helical spring 42 is precisely positioned in a preset location without the need for additional brackets or retainers. This design not only saves axial and radial space, which is beneficial for the miniaturization of the overall seal, but also ensures that the spring has no radial displacement or runout under high pressure and high speed rotation conditions, preventing additional friction or jamming caused by spring misalignment.

[0083] During the split-type installation process, after each half-ring assembly is closed, the helical spring 42 can naturally fall into the corresponding spring cavity without the need for complex alignment or auxiliary tools. The guiding function of the spring cavity helps the upper and lower split parts to align quickly and accurately, avoiding the loss of preload or assembly failure caused by misalignment on the split surface in traditional multi-part elastic systems, thus improving the efficiency of on-site installation.

[0084] To prevent the helical spring 42 from directly contacting the sealing fluid or other potentially intrusive media within the sealing cavity 9, which could lead to corrosion or affect its elastic function due to the adhesion of impurities, a protective layer is provided on the outer surface of the helical spring 42. This protective layer can be an electroplated layer (such as nickel plating), an organic coating (such as epoxy resin spraying), or a flexible anti-corrosion sleeve fitted over the spring.

[0085] It is understood that the elastic element can be any suitable form capable of providing elastic restoring force, and therefore the elastic element is not limited to the aforementioned helical spring 42, but can also be other equivalent elastic structures. For example, the elastic element can be a single conical spring or wave spring to adapt to different axial space requirements; it can also be a set of Belleville spring washers (disc springs) to provide greater elastic force; or, provided that the working conditions are met, it can also be an elastomer rubber ring, etc.

[0086] To achieve precise transmission and positioning between the rotating ring and the transmission seat 4, positioning steps are provided on both sides of the "U"-shaped transmission seat 4. Correspondingly, the medium rotating ring 5 and the atmospheric rotating ring 7 are provided with positioning grooves for precise assembly. This step-groove mating structure ensures synchronous rotation and precise axial positioning between the rotating ring and the transmission seat 4, providing a reliable mechanical guarantee for the stable fit of the sealing end face.

[0087] Thus, the intermediate shell 3, upper flange 1, lower flange 2, transmission seat 4, medium-side sealing pair, and atmospheric-side sealing pair together form a complete sealing cavity 9. A fluid interface communicating with the sealing cavity 9 is provided on the intermediate shell 3. This fluid interface can be used to introduce and / or discharge fluid into the sealing cavity 9. The fluid interface is connected to a sealing fluid system, which fills the sealing cavity 9 with a sealing fluid at a pressure higher than the medium-side pressure to achieve lubrication, cooling, and medium isolation. The sealing fluid system controls the sealing fluid pressure to be 0.05–0.15 MPa higher than the process medium pressure. The sealing fluid enters the sealing cavity 9 through the fluid interface to achieve lubrication, cooling, and medium isolation of the sealing end face.

[0088] The sealing liquid system also includes a temperature detection unit and a flow control unit. The temperature monitoring unit detects the temperature of the sealing cavity 9 in real time. When the temperature exceeds the preset threshold, the flow control unit automatically increases the supply of sealing liquid.

[0089] A pressure gauge, flow meter, or level sensor is installed inside the sealing cavity 9. If the medium-side seal fails, the process medium will seep into the sealing cavity 9, causing an abnormal increase in sealing fluid pressure, component contamination, or changes in fluid level. The sealing fluid system can then trigger an alarm or interlock shutdown based on this information. This leakage monitoring mechanism based on the sealing fluid status eliminates the need for additional complex sensors, enabling non-invasive online diagnosis of the seal's health status and providing a data foundation for predictive maintenance.

[0090] Because of the sealing fluid barrier, the atmospheric side seal only comes into contact with the clean sealing fluid, not the original process medium. Therefore, a lower-cost material combination with less stringent corrosion resistance requirements (such as silicon carbide / graphite) can be used on the atmospheric side to optimize the cost structure while ensuring overall safety and reducing maintenance requirements for the atmospheric side seal.

[0091] To ensure the long-term reliability of the drive and compensation mechanism, this invention incorporates a critical isolation seal 92. This isolation seal 92 is located between the inner wall of the positioning groove and the outer wall of the rotating shaft. In this embodiment, the isolation seal 92 is an O-ring, used to prevent process media from intruding into the first and second accommodating spaces along the surface of the rotating shaft. This completely isolates the elastic element from the process media that may cause blockage or corrosion, effectively ensuring the long-term stable operation of the seal.

[0092] It is understood that the isolation seal 92 is not limited to an O-ring, but can also be other equivalent axial sealing forms known in the art. For example, it can be an X-ring (star ring), a rectangular washer, etc. As long as it can achieve the radial sealing function at this location, it falls within the protection scope of this invention.

[0093] To achieve higher sealing performance and build multiple leak-proof barriers, the present invention sets multiple sealing rings between the mating surfaces of key components.

[0094] Specifically, a sealing ring (such as an O-ring) is provided between the mating interface of the sealing ring (i.e., the stationary ring and the moving ring) and the corresponding sealing ring seat (i.e., the stationary ring seat and the moving ring seat), forming the first static sealing defense line to prevent the medium from leaking along the outer circle of the sealing ring.

[0095] A sealing ring 91 is provided between the mating surfaces of the upper flange 1, the intermediate shell 3, and the atmospheric static ring seat 81.

[0096] A sealing ring 91 is also provided between the mating surfaces of the lower flange 2, the intermediate shell 3, and the medium stationary ring seat 61.

[0097] These sealing rings 91, distributed throughout the split intermediate shell 3, flanges, and sealing rings, together form a complete sealing network. This sealing network effectively blocks potential leakage channels between the assembly interfaces of various components, ensuring that the sealed medium or sealing fluid is completely confined within the designated flow channels and chambers, thus providing a solid sealing foundation for achieving the "zero leakage" goal of mechanical seals.

[0098] Traditional split seals typically rely on the sealed process medium itself for lubrication and cooling. When the medium itself has poor lubricity, is prone to crystallization, contains solid particles, or experiences dry running (such as medium flow interruption, high-viscosity medium startup, or other conditions without liquid lubrication), the sealing end face will wear rapidly and fail due to poor lubrication and insufficient cooling, making it difficult to operate stably under harsh conditions. To solve this problem, the medium stationary ring 6 and / or the atmospheric stationary ring 8 are made of dry-wear resistant materials. Preferably, they are made of specially impregnated dry-wear resistant graphite, which is impregnated with special solid lubricants (such as resin, Babbitt metal, molybdenum disulfide, etc.). This material has excellent self-lubricating properties, high wear resistance, and good thermal stability, and can work effectively under conditions lacking liquid lubrication (i.e., it can form a lubricating film on the end face, achieving "self-lubrication"), reducing end face wear and the risk of thermal cracking, thus maintaining normal operation for a period of time even under dry running conditions.

[0099] To ensure sealing reliability under harsh conditions such as dry grinding and high speed and high pressure, the dynamic ring uses matching materials with high hardness, high wear resistance and good toughness, such as silicon carbide, cemented carbide or high performance engineering ceramics.

[0100] The end face mating of the rotating and stationary rings is precisely designed, and their fitting parameters ensure that the sealing end faces can withstand the frictional heat and mechanical loads generated during operation. Specifically, the product of the end face specific pressure (P) and the end face linear velocity (V) of the rotating and stationary rings, i.e., the PV value, is 0.5–5.0 MPa·m / s. Preferably, for medium-load dry running conditions, the PV value ranges from 1.0 to 3.0 MPa·m / s; for high-load conditions with sealing fluid lubrication, the PV value can reach 3.0–5.0 MPa·m / s or higher.

[0101] With the above-mentioned configuration, the mechanical seal of the present invention can maintain stable operation under the expected dry grinding conditions and has a long service life and high reliability.

[0102] This invention utilizes special dry-abrasion-resistant graphite as the stationary ring material and pre-sets a sealing cavity 9 between the two end faces. This mechanical seal can select different operating modes according to actual working conditions without altering the mechanical seal's main structure.

[0103] Mode A (Dry Running Mode): No sealing fluid is introduced into the sealing cavity 9. The self-lubricating properties of the dry running graphite are directly utilized, enabling the mechanical seal to operate directly without liquid lubrication. Even if the sealing pair on the medium side fails unexpectedly, the sealing cavity 9 can effectively prevent the process medium from leaking to the outside, achieving absolute sealing (zero leakage) of hazardous media.

[0104] Mode B (Isolation Lubrication Mode): Clean sealing fluid with a pressure 0.05–0.15 MPa higher than the medium pressure is introduced into the sealing cavity 9 through the fluid interface. At this time, the sealing fluid forms a fluid barrier between the two sealing surfaces, achieving the following functions:

[0105] Lubrication: The sealing fluid provides ideal lubrication for both sealing surfaces, reducing wear, and is especially suitable for media with poor lubricity.

[0106] Cooling: The circulating sealing fluid can effectively remove the frictional heat generated by the sealing end face, preventing the end face from cracking or failing due to high temperature, greatly extending the sealing life and broadening its application in high-temperature conditions.

[0107] Absolute isolation: By adjusting the sealing fluid pressure to be higher than the medium pressure, any leakage path of the process medium to the outside is effectively blocked. Even if the medium-side sealing pair fails unexpectedly, the safe sealing fluid can still play a blocking and diluting role, achieving absolute sealing (zero leakage) of hazardous media.

[0108] Flushing: The flowing sealing fluid can flush the end faces to prevent crystals or particles from accumulating between the end faces and maintain the stability of the seal.

[0109] With its dry grinding capability and internal media isolation mechanism, it can easily handle a wide range of application scenarios, from clean media to particulate materials, from room temperature to high temperature, and from ordinary working conditions to extremely dangerous working conditions, making it extremely versatile.

[0110] This mechanical seal is suitable for rotating equipment such as reactors, agitators, and pumps, and can operate stably under toxic, flammable, and highly corrosive media, as well as dry grinding and high-temperature conditions.

[0111] To maintain the pre-compression state of the first and second elastic elements during transportation and storage, and to prevent them from loosening, the present invention includes a U-shaped detachable mounting block 10. This mounting block 10 is detachably installed between the transmission seat 4 and the moving ring seat, and its U-shaped structure provides mechanical restraint, thereby reliably maintaining the preset compression of the elastic elements. During on-site installation, simply removing the block and sealing the seal restores normal operation.

[0112] The presence of the mounting block 10 serves as a visual indicator of an "inactive" state. If the user discovers a missing or loose block, they can promptly report any potential shipping damage. In some implementations, anti-counterfeiting labels or batch codes can also be integrated for easier quality traceability and after-sales service management.

[0113] It is understood that the mounting block 10 is not limited to the U-shaped structure mentioned above. It can also be other shapes that can achieve the same clamping and limiting functions, such as C-shaped, L-shaped or block-shaped structures.

[0114] Working principle:

[0115] Rotary module pre-assembly and transportation: In the factory, the helical spring 42, the moving ring seat, the moving ring, and the transmission seat 4 are assembled into a complete rotary module using pins 41, and the spring is compressed to the working state. Then, a removable mounting clip 10 (usually inserted between the groove of the transmission seat 4 and the moving ring seat) is used to hold the module in place, maintaining the pre-compression state of the spring and ensuring safe transportation and handling.

[0116] On-site installation: Wrap the lower flange 2, medium stationary ring seat 61, and medium stationary ring 6 around the shaft and initially close them. Fix the medium stationary ring seat 61 to the lower flange 2 with bolts.

[0117] The split pieces of the rotating module are wrapped around the shaft, closed, and fastened with screws to make it a whole.

[0118] Wrap the upper flange 1, atmospheric stationary ring seat 81, and atmospheric stationary ring 8 around the shaft and initially close them. Then, fix the atmospheric stationary ring seat 81 to the upper flange 1 with bolts.

[0119] Use long screws to press the stationary ring flange, sealing housing, and lower flange 2 through and tighten them.

[0120] Finally, remove the mounting clip 10. The spring force is released instantly and acts directly and evenly on the two moving rings through the moving ring seat, pushing them to fit tightly against their corresponding stationary rings to form an initial seal.

[0121] This invention integrates a split double-end face structure with a sealing cavity, successfully combining "convenient installation and maintenance" with "high-level safety performance," providing a high-performance mechanical seal solution.

Claims

1. A double-end-face split mechanical seal, for fitting around a rotating shaft, characterized in that, It includes a split upper flange, a lower flange, an intermediate housing, a transmission seat, a medium moving ring, a medium stationary ring, an atmospheric moving ring, an atmospheric stationary ring, and a detachable mounting block; the transmission seat is used to fix it on the rotating shaft, the intermediate housing is sleeved on the outside of the transmission seat, and the upper flange and lower flange are respectively connected to the axial ends of the intermediate housing; the medium stationary ring is installed with the lower flange, and the atmospheric stationary ring is installed with the upper flange; The medium dynamic ring and the atmospheric dynamic ring are located on both sides of the transmission seat along the axial direction and are connected to the transmission seat to form an integrated synchronous rotation module; A first accommodating space is provided between the transmission seat and the medium moving ring, and a second accommodating space is provided between the transmission seat and the atmospheric moving ring; a first elastic element is provided in the first accommodating space to provide axial clamping force to the medium moving ring, pushing the medium moving ring to fit against the end face of the medium stationary ring to form a medium-side sealing pair; a second elastic element is provided in the second accommodating space to provide axial clamping force to the atmospheric moving ring, pushing the atmospheric moving ring to fit against the end face of the atmospheric stationary ring to form an atmospheric-side sealing pair; The intermediate shell, upper flange, lower flange, medium static ring, and atmospheric static ring together form a sealed cavity; at least one of the intermediate shell, upper flange, and lower flange has a fluid interface communicating with the sealed cavity. The mounting block is installed in the first and second accommodating spaces during transportation and storage to limit the axial displacement of the moving ring relative to the transmission seat and maintain the pre-compression state of the first and second elastic elements. The transmission seat is provided with positioning steps on both sides, and the medium moving ring and the atmospheric moving ring are provided with positioning grooves that are assembled with the positioning steps. The medium dynamic ring and the atmospheric dynamic ring are connected to the transmission base through at least one transmission component to achieve integrated synchronous rotation drive; The transmission component includes a pin disposed on the transmission seat, and a medium moving ring seat and an atmospheric moving ring seat respectively cooperating with the pin. The medium moving ring seat and the atmospheric moving ring seat are connected to the axial ends of the transmission seat through the same pin, thereby realizing integrated synchronous rotation drive; since the medium moving ring seat and the atmospheric moving ring seat share the same pin, their angular positions with the transmission seat are rigidly locked, ensuring that the two moving rings always maintain strict phase during rotation. An isolation seal is provided between the inner wall of the positioning groove and the outer wall of the rotating shaft to prevent the medium from entering the first accommodating space and the second accommodating space.

2. The double-end-face split mechanical seal as described in claim 1, characterized in that, All split components use stepped or V-shaped interfaces for their mating surfaces.

3. The double-end-face split mechanical seal as described in claim 1, characterized in that, The fluid interface is connected to the sealing liquid system, which fills the sealing cavity with a sealing liquid at a pressure higher than that of the sealed process medium to lubricate, cool, and isolate the end faces of the medium-side sealing pair and the atmospheric-side sealing pair.

4. A double-end-face split mechanical seal as described in claim 1, characterized in that, Both the first elastic element and the second elastic element are helical springs arranged uniformly along the circumferential direction.

5. A double-end-face split mechanical seal as described in claim 1, characterized in that, The medium stationary ring and / or atmospheric stationary ring are made of dry-grind-resistant graphite impregnated with solid lubricant.

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