Method for prolonging the life of a graphite gasket

Abstract

This invention discloses a method for extending the lifespan of a graphite circumferential sealing structure, belonging to the field of mechanical seal technology. The graphite circumferential sealing structure includes a raceway, a segmented graphite sealing ring, and at least one adjusting sleeve. The method includes: initially, forming a dynamic seal between the inner bore surface of the graphite sealing ring and the outer circumferential surface of the raceway; when the inner bore surface of the graphite sealing ring wears down, performing a first adjustment by fitting and fixing a first adjusting sleeve outside the raceway, forming a dynamic seal between the inner bore surface of the graphite sealing ring and the outer circumferential surface of the first adjusting sleeve; when it wears down again, performing a second adjustment by fitting and fixing a second adjusting sleeve outside the first adjusting sleeve, forming a dynamic seal between the inner bore surface of the graphite sealing ring and the outer circumferential surface of the second adjusting sleeve; and so on, by sequentially fitting and fixing adjusting sleeves, the inner bore surface of the graphite sealing ring sequentially forms a dynamic seal with the outer circumferential surface of each adjusting sleeve, achieving multi-stage lifespan extension.

Description

Technical Field

[0001] This invention relates to the field of mechanical seal technology, specifically to a method for extending the lifespan of a graphite circumferential seal structure, used for sealing bearing cavities in high-speed rotating machinery such as aero engines and gas turbines. Background Technology

[0002] In turbomachinery such as aero engines and gas turbines, which contain high-speed rotating components, lubricating oil must be supplied and recovered into the bearing cavity to ensure reliable bearing operation, thereby achieving bearing lubrication and cooling. The lubricating oil seal design at the junction of the rotor and stator in the bearing cavity must ensure efficient and reliable sealing; this function is typically achieved using a graphite circumferential seal device.

[0003] like Figure 1 As shown, in a typical graphite circumferential sealing device, when in operation, the inner surface of the segmented graphite sealing ring, which is subjected to force by a circumferential spring, is tightly fitted with the outer circumferential surface of the metal raceway that rotates with the rotor, forming a contact dynamic seal.

[0004] Because graphite has low hardness and good self-lubricating properties but is easily worn, while running tracks are usually made of high-hardness, wear-resistant metal materials, uneven wear will inevitably occur after the device has been in operation for a long time. This means that the inner surface of the graphite sealing ring experiences significant material loss, leading to an increase in its inner diameter, while the outer diameter of the running track remains almost unchanged. This physical phenomenon causes two serious problems that directly lead to seal failure: First, the curvature of the inner surface of the graphite sealing ring and the outer circumference of the running track are no longer consistent, creating an unclosable leakage gap between them, resulting in a severe decrease in sealing performance; second, to compensate for wear, the segmented graphite rings gradually contract inward under the action of circumferential spring force, and the circumferential gap between the segments continuously decreases. When the wear accumulates to a certain extent, this circumferential gap will completely close, and the graphite ring segments will jam against each other, completely losing their wear compensation ability. At this point, the sealing device fails.

[0005] Faced with the problem of end-of-life sealing devices due to wear, existing technologies typically only allow for complete replacement after device failure. This results in high spare parts costs, extensive disassembly and maintenance, and does not meet the requirements of a green circular economy. Patent application CN114492056A discloses a method and system for calculating the working clearance of a floating ring seal. This technology focuses on optimizing initial structural parameters during the design phase by accurately calculating the impact of physical effects such as temperature and centrifugal force on the sealing clearance to prevent graphite ring seizing or excessive clearance during initial operation. However, this solution focuses entirely on the "design phase" of the sealing device and fails to address a fundamental "usage phase" problem: how to restore the sealing performance and extend the service life of the sealing device in a simple and economical way after long-term use and significant wear on the inner surface of the graphite ring. There is currently no effective solution to this problem in existing technologies.

[0006] Therefore, there is an urgent need to develop a simple and low-cost method that can restore the sealing ability of graphite sealing rings and significantly extend the service life of graphite circumferential sealing structures after wear occurs on the inner surface of the graphite sealing ring. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for extending the lifespan of a graphite circumferential sealing structure. This invention introduces an adjusting sleeve that can be layered and fixed between the runway and the graphite sealing ring, thereby increasing the effective outer diameter in a stepwise manner to compensate for the wear on the inner surface of the graphite sealing ring and restore the compensation gap of the segmented ring, thus achieving multiple life extensions for the graphite circumferential sealing structure.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for extending the life of a graphite circumferential sealing structure, the graphite circumferential sealing structure including a raceway for rotating with a rotor and a segmented graphite sealing ring, the graphite circumferential sealing structure also including at least one adjusting sleeve.

[0009] In the initial use state, the inner hole surface of the graphite sealing ring forms a dynamic seal with the outer peripheral surface of the runway; When the inner bore surface of the graphite sealing ring is worn to the point where adjustment is required, the first adjustment is performed: the first adjusting sleeve is fitted and fixed outside the runway, and then the graphite sealing ring is reinstalled, so that the inner bore surface of the graphite sealing ring and the outer circumferential surface of the first adjusting sleeve form a dynamic seal.

[0010] When the bore surface of the graphite sealing ring is worn again to the point that adjustment is required, a second adjustment is performed: the second adjustment sleeve is fitted and fixed outside the first adjustment sleeve, and then the graphite sealing ring is reinstalled so that the inner bore surface of the graphite sealing ring and the outer circumferential surface of the second adjustment sleeve form a dynamic seal.

[0011] By sequentially installing and fixing the adjusting sleeves, the inner surface of the graphite sealing ring forms a dynamic seal with the outer circumferential surface of each adjusting sleeve, thereby extending the lifespan of the graphite circumferential sealing structure in multiple stages.

[0012] In a preferred embodiment, all adjusting sleeves at each level are fitted and fixed via threaded engagement. Specifically, the first adjusting sleeve is fixed by engaging an external thread on the outer cylindrical surface of the left end of the runway with an internal thread on the inner wall of the left end of the first adjusting sleeve; the second adjusting sleeve is fixed by engaging an external thread on the outer cylindrical surface of the left end of the first adjusting sleeve with an internal thread on the inner wall of the left end of the second adjusting sleeve; and so on, all adjusting sleeves at each level are fitted and fixed via threaded engagement. Threaded connections have the advantages of simple structure, convenient assembly and disassembly, and reliable connection.

[0013] Furthermore, to achieve reliable axial positioning of the adjusting sleeve, a chamfer is provided at the right end of the runway, and a first tapered section is provided at the right end of the first adjusting sleeve. During the first adjustment, when the internal thread at the left end of the first adjusting sleeve is tightened with the external thread at the left end of the runway, the inner tapered surface of the first tapered section engages with the chamfer, thus axially limiting the first adjusting sleeve. A second tapered section is provided at the right end of the second adjusting sleeve. During the second adjustment, when the internal thread at the left end of the second adjusting sleeve is tightened with the external thread at the left end of the first adjusting sleeve, the inner tapered surface of the second tapered section engages with the outer tapered surface of the first tapered section, thus axially limiting the second adjusting sleeve. This process continues, with tapered sections provided at each stage of the adjusting sleeve to achieve cascaded axial positioning. This design provides both auxiliary axial positioning and locking, and also creates a smoothly transitioning tapered surface, facilitating the installation of the graphite sealing ring.

[0014] Furthermore, the inner diameter of the first adjusting sleeve matches the outer diameter of the runway, the inner diameter of the second adjusting sleeve matches the outer diameter of the first adjusting sleeve, and so on, with the inner diameter of the next-level adjusting sleeve matching the outer diameter of the previous-level adjusting sleeve, to ensure coaxiality and fitting accuracy between the sleeves at each level.

[0015] Furthermore, the graphite sealing structure also includes a circumferential tension spring and a segmented circumferential braking ring; the circumferential braking ring is sleeved on the outer circumferential surface of the graphite sealing ring; the circumferential tension spring is sleeved on the outer circumferential surface of the circumferential braking ring, and is used to apply a radial load to the circumferential braking ring so that the inner hole surface of the graphite sealing ring is in close contact with the outer circumferential surface of the raceway or adjusting sleeve to form a dynamic seal.

[0016] Furthermore, the graphite sealing structure also includes a sealing seat with a cavity open at the left end; the graphite sealing ring, circumferential brake pad, and circumferential tension spring are all disposed within the inner cavity of the sealing seat; the right end of the racetrack extends from the central through hole on the right side wall of the housing; a retaining ring groove is provided on the inner wall surface of the left end of the sealing seat, and a retaining ring is installed in the retaining ring groove; a wave spring and a retaining ring are sequentially installed between the right side of the retaining ring and the left side of the graphite sealing ring; the right end face of the retaining ring abuts against the left end face of the graphite sealing ring to form a static seal; the left side of the wave spring abuts against the retaining ring, and the right side face of the wave spring abuts against the retaining ring; the wave spring is always in a compressed state, used to generate a rightward thrust on the retaining ring, so that the right end face of the graphite sealing ring abuts against the inner cavity side wall of the sealing seat to form a static seal. With this structure, the graphite sealing ring can obtain reliable sealing preload in both the axial and radial directions.

[0017] Furthermore, to prevent undesirable circumferential rotation of the components, a first anti-rotation pin is inserted into the right side wall of the sealing seat using an interference fit; a first U-shaped groove is formed on the right side surface of the circumferential brake ring; the left end of the first anti-rotation pin is slidably engaged with the first U-shaped groove. A second anti-rotation pin is inserted into the retaining ring using an interference fit; a second U-shaped groove is formed on the left side surface of the circumferential brake ring; the right end of the second anti-rotation pin is slidably engaged with the second U-shaped groove. The first and second anti-rotation pins together serve to circumferentially limit the circumferential brake ring, but the segmented units on the circumferential brake ring can float radially to ensure that they can effectively transmit the radial force of the circumferential spring.

[0018] Furthermore, a third anti-rotation pin is inserted into the outer circumferential surface of the retaining ring using an interference fit; an axial groove is formed on the inner wall surface of the left end of the sealing seat; the radial outer end of the third anti-rotation pin is slidably engaged with the axial groove to circumferentially limit the retaining ring, but the retaining ring can move axially under the action of the wave spring to ensure that it can always press against the end face of the graphite sealing ring.

[0019] Furthermore, a tubular body is integrally formed on the left end face of the retaining ring; the wave spring is sleeved on the tubular body, and the outer cylindrical surface of the tubular body is spaced apart from the inner hole surface of the retaining ring. This tubular body provides radial positioning for the wave spring, preventing it from shifting during operation.

[0020] Furthermore, there are at least two graphite sealing rings, and the circumferential gaps between two adjacent graphite sealing rings are staggered.

[0021] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: (1) This invention directly addresses the core pain point of graphite circumferential sealing devices reaching the end of their service life due to wear on the inner bore surface of the graphite sealing ring, breaking through the traditional maintenance approach of replacing the entire device. Through an innovative "racetrack + multi-stage adjusting sleeve" combination scheme, the mating relationship of the main sealing surface is corrected and rematched in a stepwise manner with extremely low cost and simple and reliable operation, without changing the main structure and installation space of the original sealing device. Whenever the inner bore surface of the graphite sealing ring wears, a new adjusting sleeve is fitted and fixed, making its outer circumferential surface a new contact dynamic sealing mating surface, thereby extending the service life of the graphite circumferential sealing structure from one cycle to multiple cycles.

[0022] (2) This method is not limited to a specific fixing method. Any means that can realize the step-by-step installation and reliable fixing of the adjusting sleeve can be applied, and it has a wide range of engineering application prospects.

[0023] (3) This scheme can significantly extend the service life of the whole set of equipment, save the cost of use, improve the efficiency of equipment use, and has the outstanding advantages of simple operation, convenient disassembly and assembly, and significant economic benefits. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of a typical graphite circumferential sealing principle in existing technology.

[0026] Figure 2 This is a schematic diagram of the graphite circumferential sealing structure in the life extension method provided by the present invention. The diagram has been adjusted twice.

[0027] Figure 3 This is a schematic diagram of the runway structure in this invention.

[0028] Figure 4 This is a schematic diagram of the structure of the first adjusting sleeve in this invention.

[0029] Figure 5 This is a schematic diagram of the structure of the second adjusting sleeve in this invention.

[0030] Figure 6 This is a schematic diagram showing the first adjusting sleeve engaging with the runway during the first adjustment in this invention.

[0031] Figure 7This is a schematic diagram showing the second adjusting sleeve, the first adjusting sleeve, and the runway after they are engaged during the second adjustment in this invention.

[0032] Explanation of reference numerals: 1. Runway; 1a. Chamfer; 2. First adjusting sleeve; 2a. First conical section; 3. Second adjusting sleeve; 3a. Second conical section; 4. Graphite sealing ring; 5. Circumferential tension spring; 6. Circumferential brake pad; 6a. First U-groove; 6b. Second U-groove; 7. First anti-rotation pin; 8. Sealing seat; 8a. Axial groove; 9. Retaining ring; 9a. Tubular body; 10. Second anti-rotation pin; 11. Wave spring; 12. Elastic retaining ring; 13. Third anti-rotation pin. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0035] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0036] Combination Figures 2 to 7 The image shows a specific embodiment of a method for extending the lifespan of a graphite circumferential sealing structure provided by the present invention. In this embodiment, the graphite circumferential sealing structure includes a racetrack 1, a segmented graphite sealing ring 4, and at least one adjusting sleeve. In this embodiment, an example is provided that includes a first adjusting sleeve 2 and a second adjusting sleeve 3, forming a two-stage adjusting sleeve.

[0037] Combination Figure 3As shown, runway 1 is designed as an annular component that rotates together with the rotor. An external thread is provided on the outer cylindrical surface at the left end of runway 1. A chamfer 1a is provided at the right end of runway 1.

[0038] Combination Figure 4 As shown, the first adjusting sleeve 2 is an annular component, and its inner diameter matches the outer diameter of the runway 1. An internal thread matching the external thread of the runway 1 is provided on the inner wall of the left end of the first adjusting sleeve 2. An external thread is also provided on the outer circumference of the left end of the first adjusting sleeve 2 for connecting to the next adjusting sleeve. At the right end of the first adjusting sleeve 2, a first tapered section 2a is provided, the shape and angle of which match the chamfer 1a at the right end of the runway 1.

[0039] Combination Figure 5 As shown, the structure of the second adjusting sleeve 3 is similar to that of the first adjusting sleeve 2, but its size is larger. The inner diameter of the second adjusting sleeve 3 matches the outer diameter of the first adjusting sleeve 2. An internal thread matching the external thread of the first adjusting sleeve 2 is provided on the inner wall of the left end of the second adjusting sleeve 3. A second tapered section 3a is provided at the right end of the second adjusting sleeve 3, the shape and angle of the inner tapered surface of which match the outer tapered surface of the first tapered section 2a. If more life extension stages are required, a third, fourth, or even nth adjusting sleeve can be designed according to this pattern, forming a series of sleeves with progressively increasing outer diameters.

[0040] The graphite sealing structure in this embodiment also includes a circumferential tension spring 5, a segmented circumferential braking ring 6, and a sealing seat 8. The sealing seat 8 has a cavity with an open left end. The graphite sealing ring 4, the circumferential braking ring 6, and the circumferential tension spring 5 are all disposed in the inner cavity of the sealing seat 8. The right end of the racetrack 1 extends from the central through hole on the right side wall of the sealing seat 8.

[0041] A circumferential brake ring 6 is sleeved on the outer circumferential surface of a graphite sealing ring 4, and a circumferential tension spring 5 is sleeved on the outer circumferential surface of a circumferential brake ring 6 to apply a radial load to the circumferential brake ring 6 so that the inner hole surface of the graphite sealing ring 4 is in close contact with the outer circumferential surface of the raceway 1 or the adjusting sleeve to form a dynamic seal.

[0042] A retaining ring groove is provided on the inner wall of the left end of the sealing seat 8, and a retaining ring 12 is installed in the retaining ring groove. A wave spring 11 and a retaining ring 9 are installed sequentially between the right side of the retaining ring 12 and the left side of the graphite sealing ring 4. The right end of the retaining ring 9 abuts against the left end of the graphite sealing ring 4 to form a static seal. The left side of the wave spring 11 abuts against the retaining ring 12, and the right side of the wave spring 11 abuts against the retaining ring 9. The wave spring 11 is always in a compressed state, which is used to generate a rightward thrust on the retaining ring 9 so that the right end of the graphite sealing ring 4 abuts against the inner wall of the sealing seat 8 to form a static seal.

[0043] In this embodiment, there are two graphite sealing rings 4, and the circumferential gaps on these two graphite sealing rings 4 are staggered, that is, the circumferential gaps formed by the segmented graphite mating surfaces on the two graphite sealing rings 4 are staggered to ensure the sealing effect.

[0044] In this embodiment, multiple anti-rotation structures are provided to prevent undesirable circumferential rotation of the components. A first anti-rotation pin 7 is inserted into the right side wall of the sealing seat 8 using an interference fit; a first U-shaped groove 6a is formed on the right side surface of the circumferential brake ring 6; the left end of the first anti-rotation pin 7 is slidably engaged with the first U-shaped groove 6a. A second anti-rotation pin 10 is inserted into the retaining ring 9 using an interference fit; a second U-shaped groove 6b is formed on the left side surface of the circumferential brake ring 6; the right end of the second anti-rotation pin 10 is slidably engaged with the second U-shaped groove 6b. The first anti-rotation pin 7 and the second anti-rotation pin 10 together serve to circumferentially limit the circumferential brake ring 6, but the segmented individual units on the circumferential brake ring 6 can float radially.

[0045] A third anti-rotation pin 13 is inserted into the outer circumferential surface of the retaining ring 9 by an interference fit; an axial groove 8a is provided on the inner wall of the left end of the sealing seat 8; the radial outer end of the third anti-rotation pin 13 is slidably engaged with the axial groove 8a to circumferentially limit the retaining ring 9, but the retaining ring 9 can move axially under the force of the wave spring 11.

[0046] A tubular body 9a is integrally formed on the left end face of the retaining ring 9; the wave spring 11 is sleeved on the tubular body 9a, and the outer cylindrical surface of the tubular body 9a is spaced apart from the inner hole surface of the retaining ring 12, providing reliable radial positioning for the wave spring 11.

[0047] This embodiment demonstrates how to extend the lifespan of a graphite circumferential sealing structure using the above structure, specifically including three stages: Initial usage state (first service life): like Figure 1 As shown, in its brand-new state, the segmented graphite sealing ring 4 is directly installed on the outer circumferential surface of the runway 1. At this time, the inner bore surface of the graphite sealing ring 4 forms a dynamic seal with the outer circumferential surface of the runway 1. The circumferential tension spring 5 applies a radial load to the graphite sealing ring 4 through the circumferential braking ring 6 to compensate for slight wear during initial operation. The wave spring 11 applies an axial thrust to the graphite sealing ring 4 through the retaining ring 9, causing its right end face to form a static seal with the inner cavity sidewall of the sealing seat 8. At this time, the circumferential gap between the segments of the graphite sealing ring 4 is maintained at a reasonable initial value. As the device operates for a long time, the inner bore surface of the graphite sealing ring 4 gradually wears, its inner diameter increases, and the circumferential gap between the segments gradually decreases.

[0048] First life extension operation (entering the second service life): When the device reaches the end of its first service life, and the inner hole surface of the graphite sealing ring 4 is worn, causing the sealing performance to fail to meet the standard, the service life extension method of the present invention is executed to perform the first adjustment.

[0049] First, the machine is stopped and the graphite sealing ring 4, circumferential brake ring 6 and sealing seat 8 are axially removed from runway 1, so that runway 1 is fully exposed.

[0050] Then, take the first adjusting sleeve 2, align its inner diameter face with the outer diameter face of the runway 1, and move it axially until its left-end internal thread contacts the left-end external thread of the runway 1. Rotate the first adjusting sleeve 2 to screw its internal thread and external thread together and tighten it continuously, thereby putting the first adjusting sleeve 2 on and fixing it outside the runway 1. In the final stage of the tightening process, the inner conical surface of the first conical section 2a at the right end of the first adjusting sleeve 2 will fit tightly against the chamfer 1a at the right end of the runway 1, as shown below. Figure 6 As shown. This fit provides auxiliary axial positioning and forms a smoothly transitioning conical surface, facilitating the installation of the graphite sealing ring 4.

[0051] After installation, the first adjusting sleeve 2 is radially stacked on the runway 1, increasing the effective outer circumferential diameter that mates with the graphite sealing ring 4. This diameter increment specifically corresponds to the wear amount on the inner bore surface of the graphite sealing ring 4 during the first service life.

[0052] Finally, the graphite sealing ring 4, circumferential braking ring 6, and sealing seat 8 are axially pushed in and reinstalled onto the outer circumferential surface of the first adjusting sleeve 2. At this point, the inner bore surface of the graphite sealing ring 4 forms a new dynamic seal with the outer circumferential surface of the first adjusting sleeve 2. The enlarged effective outer circumferential diameter is re-matched with the enlarged inner bore diameter of the graphite sealing ring 4 after wear, and the mating surfaces regain a good fit. The device enters its second service life.

[0053] Second life extension operation (entering the third service life): When the inner surface of the graphite sealing ring 4 is severely worn again at the end of the second service life of the device, and the above problem recurs, the second adjustment of this method can be performed.

[0054] Similar to the steps described above, remove the graphite sealing ring 4 and other components from the first adjusting sleeve 2. Then, take the second adjusting sleeve 3 and place it over the installed first adjusting sleeve 2, aligning the internal thread at the left end of the second adjusting sleeve 3 with the external thread at the left end of the first adjusting sleeve 2.

[0055] Rotate the second adjusting sleeve 3 so that its internal thread and external thread are screwed together and tightened, thereby fitting and fixing the second adjusting sleeve 3 outside the first adjusting sleeve 2. During the tightening process, the inner conical surface of the second conical section 3a at the right end of the second adjusting sleeve 3 is in contact with the outer conical surface of the first conical section 2a of the first adjusting sleeve 2, as shown. Figure 4 As shown, cascaded axial positioning is achieved.

[0056] Thus, the second adjusting sleeve 3 achieves radial stacking again based on the first adjusting sleeve 2, and the effective outer circumferential diameter is further increased to match the additional wear generated by the inner hole surface of the graphite sealing ring 4 during the second service life.

[0057] Reinstall the graphite sealing ring 4 and other components to form a new dynamic seal between its inner bore surface and the outer circumferential surface of the second adjusting sleeve 3. The circumferential gap of the segments is restored again, and the device enters its third service life.

[0058] In this way, the life extension method can be repeated. Each life extension operation involves putting on and fixing a new adjusting sleeve with a larger outer diameter outside the current outermost adjusting sleeve, so that the inner surface of the graphite sealing ring 4 forms a dynamic seal with the outer circumferential surface of the newest adjusting sleeve, until the adjusting sleeves are used up or other components of the device reach their life limit.

[0059] It should be noted that in this embodiment, the adjusting sleeve is fitted and fixed via a threaded connection, which is simple in structure and easy to assemble and disassemble. The direction of the threaded connection is preferably set opposite to the rotation direction of the rotor during operation, so that the threaded connection has a self-locking effect under working load, preventing loosening. In other embodiments, the fitting and fixing can also be achieved using interference fits, snap-fit ​​connections, or other mechanical fixing methods, as long as reliable positioning of the adjusting sleeve in the working state can be guaranteed.

[0060] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for extending the lifespan of a graphite circumferential sealing structure, the graphite circumferential sealing structure comprising a raceway (1) for rotating with a rotor and a segmented graphite sealing ring (4), characterized in that, The graphite circumferential sealing structure also includes at least one adjusting sleeve; In the initial use state, the inner hole surface of the graphite sealing ring (4) forms a dynamic seal with the outer peripheral surface of the runway (1); When the inner hole surface of the graphite sealing ring (4) is worn to the point that adjustment is required, the first adjustment is performed: the first adjustment sleeve (2) is sleeved and fixed outside the runway (1), and then the graphite sealing ring (4) is put back, so that the inner hole surface of the graphite sealing ring (4) and the outer peripheral surface of the first adjustment sleeve (2) form a dynamic seal. When the hole surface of the graphite sealing ring (4) is worn again to the point that adjustment is required, a second adjustment is performed: the second adjustment sleeve (3) is fitted and fixed outside the first adjustment sleeve (2), and then the graphite sealing ring (4) is put back, so that the inner hole surface of the graphite sealing ring (4) and the outer peripheral surface of the second adjustment sleeve (3) form a dynamic seal. By successively installing and fixing the adjusting sleeves, the inner surface of the graphite sealing ring (4) is made to form a dynamic seal with the outer circumferential surface of each adjusting sleeve in turn, thereby achieving multi-stage life extension of the graphite circumferential sealing structure.

2. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 1, characterized in that, The first adjusting sleeve (2) is fixed by the external thread provided on the outer cylindrical surface of the left end of the runway (1) and the internal thread provided on the inner wall of the left end of the first adjusting sleeve (2); The second adjusting sleeve (3) is fixed by the external thread provided on the outer cylindrical surface of the left end of the first adjusting sleeve (2) and the internal thread provided on the inner wall of the left end of the second adjusting sleeve (3); Similarly, each adjusting sleeve is fitted and fixed through a threaded connection.

3. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 2, characterized in that, A chamfer (1a) is provided at the right end of the runway (1), and a first tapered section (2a) is provided at the right end of the first adjusting sleeve (2). During the first adjustment, when the internal thread of the left end of the first adjusting sleeve (2) is tightened with the external thread of the left end of the runway (1), the inner tapered surface of the first tapered section (2a) is made to fit against the chamfer (12) to axially limit the first adjusting sleeve (2). A second tapered section (3a) is provided at the right end of the second adjusting sleeve (3); in the second adjustment, when the internal thread at the left end of the second adjusting sleeve (3) is tightened with the external thread at the left end of the first adjusting sleeve (2), the inner tapered surface of the second tapered section (3a) is made to fit with the outer tapered surface of the first tapered section (2a) to axially limit the second adjusting sleeve (3); Similarly, each adjusting sleeve is equipped with a tapered section to achieve cascaded axial positioning.

4. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 1, characterized in that, The inner diameter of the first adjusting sleeve (2) matches the outer diameter of the runway (1), the inner diameter of the second adjusting sleeve (3) matches the outer diameter of the first adjusting sleeve (2), and so on, the inner diameter of the next adjusting sleeve matches the outer diameter of the previous adjusting sleeve.

5. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 1, characterized in that, The graphite sealing structure also includes a circumferential tension spring (5) and a segmented circumferential braking ring (6); the circumferential braking ring (6) is sleeved on the outer circumferential surface of the graphite sealing ring (4); the circumferential tension spring (5) is sleeved on the outer circumferential surface of the circumferential braking ring (6) to apply a radial load to the circumferential braking ring (6) so that the inner hole surface of the graphite sealing ring (4) is in close contact with the outer circumferential surface of the raceway (1) or the adjusting sleeve to form a dynamic seal.

6. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 5, characterized in that, The graphite sealing structure also includes a sealing seat (8), which has a cavity with an open left end; The graphite sealing ring (4), the circumferential brake pad (6), and the circumferential tension spring (5) are all disposed in the inner cavity of the sealing seat (8); The right end of the runway (1) extends from the central through hole on the right side wall of the housing (8); A retaining ring groove is provided on the inner wall surface of the left end of the sealing seat (8), and a retaining ring (12) is installed in the retaining ring groove. A wave spring (11) and a retaining ring (9) are sequentially installed between the right side of the retaining ring (12) and the left side of the graphite sealing ring (4); the right end of the retaining ring (9) abuts against the left end of the graphite sealing ring (4) to form a static seal; the left side of the wave spring (11) abuts against the retaining ring (12), and the right side of the wave spring (11) abuts against the retaining ring (9); the wave spring (11) is always in a compressed state, used to generate a rightward thrust on the retaining ring (9), so that the right end of the graphite sealing ring (4) abuts against the inner cavity sidewall of the sealing seat (8) to form a static seal.

7. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 6, characterized in that, A first anti-rotation pin (7) is inserted into the right side wall of the sealing seat (8) in an interference fit manner; a first U-shaped groove (6a) is provided on the right side surface of the circumferential brake ring (6); the left end of the first anti-rotation pin (7) is slidably engaged with the first U-shaped groove (6a); the first anti-rotation pin (7) is used to circumferentially limit the circumferential brake ring (6), but the segmented units on the circumferential brake ring (6) can float radially.

8. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 6, characterized in that, A second anti-rotation pin (10) is inserted into the retaining ring (9) with an interference fit; a second U-shaped groove (6b) is provided on the left side of the circumferential brake ring (6); the left end of the second anti-rotation pin (10) is slidably engaged with the first U-shaped groove (6a); the second anti-rotation pin (10) is used to circumferentially limit the circumferential brake ring (6), but the individual segments on the circumferential brake ring (6) can float radially.

9. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 6, characterized in that, A third anti-rotation pin (13) is inserted into the outer circumferential surface of the retaining ring (9) by an interference fit; an axial groove (8a) is provided on the inner wall of the left end of the sealing seat (8); the radial outer end of the third anti-rotation pin (13) slides with the axial groove (8a) to circumferentially limit the retaining ring (9), but the retaining ring (9) can move axially under the force of the wave spring (11).

10. The method for extending the lifespan of a graphite circumferential sealing structure according to claim 6, characterized in that, A tubular body (9a) is integrally formed on the left end face of the retaining ring (9); the wave spring (11) is sleeved on the tubular body (9a), and the outer cylindrical surface of the tubular body (9a) is spaced apart from the inner hole surface of the retaining ring (12).

Images