Engine transmission gear shaft end lubricating oil sealing structure and aero-engine

Abstract

The invention discloses an engine transmission gear shaft end lubricating oil sealing structure and an aero-engine, the engine transmission gear shaft end lubricating oil sealing structure comprises a sealing protection ring, a sealing assembly, a mounting seat, a seat cover and an oil leakage nozzle, and a sealing plug is arranged in an inner hole of a transmission gear shaft; the sealing protection ring is arranged on the transmission gear shaft in a sleeving mode and fixedly connected with the transmission gear shaft through a nut. The sealing assembly is installed on the outer circle of the sealing protection ring and comprises a static ring and a rotating ring, and annular graphite is arranged on the end face of the rotating ring and forms a friction pair with the static ring. And the oil leakage nozzle is arranged at the lower end of the accessory casing, is communicated with oil leakage holes of the mounting seat and the accessory casing, and is used for collecting and monitoring leaked lubricating oil. The transmission gear shaft and the sealing structure thereof are reliable in work, lubricating oil can be effectively prevented from leaking into electrical accessories, and the problem that adverse effects are caused to an engine and the electrical accessories when lubricating oil leakage is increased or exceeds the standard is effectively solved.

Description

Technical Field

[0001] This invention belongs to the technical field of aero-engine transmission gear shafts, and in particular, relates to an oil sealing structure for the end of an engine transmission gear shaft. This invention also includes an aero-engine. Background Technology

[0002] The gear shaft of the accessory drive system of a certain type of turboprop engine is used to drive external electrical accessories. Since lubricating oil is not allowed to enter these accessories, the gear shaft operates at high speeds, has high output power, and requires a long service life. However, the installation space in aero-engines is limited, thus requiring high sealing performance at the gear shaft end. Existing transmission sealing devices are ill-suited to the compact structure, high linear velocity, high temperature, and long operating time of the turboprop engine's gear shaft end face sealing environment. Improper sealing design can lead to lubricating oil leakage into the electrical accessories or affect the lubrication of parts on the gear shaft (gears and their bearings), jeopardizing the safe operation of the engine.

[0003] On the other hand, since the gear shaft end sealing structure rotates at high speed with the gear shaft, the sealing surface should be in a good lubrication state to ensure that the seal is not worn too quickly. However, in the presence of an oil film, there will inevitably be a small amount of leakage. Therefore, in order to effectively monitor the sealing effect of the sealing structure, a drainage structure after a small amount of lubricating oil leakage needs to be designed. At the same time, if the sealing performance of the sealing structure weakens and lubricating oil leakage occurs, it needs to be able to be replaced on site for convenient maintenance and without affecting the reliable use of this type of engine.

[0004] Patent application CN119062409A discloses a shaft end sealing structure and an aero-engine, including a bearing mounting base, a rotating shaft rotatably mounted within the bearing mounting base, a sealing runway interference-fitted onto the outer wall of the rotating shaft, and a static seal fitted onto the sealing runway and fixed to the bearing mounting base. The static seal includes a sealing oil collection pan and a sealing mounting base arranged sequentially along the axial direction of the sealing runway, and a lip seal ring interference-fitted between the sealing oil collection pan and the sealing mounting base. The side of the lip seal ring closer to the bearing, together with the sealing mounting base and the sealing runway, forms a first sealing cavity; the side of the lip seal ring farther from the bearing, together with the sealing oil collection pan and the sealing runway, forms a second sealing cavity. The lip seal ring is tightened against the outer wall of the sealing runway to seal the first sealing cavity, and the sealing oil collection pan abuts against the outer wall of the sealing runway to seal the second sealing cavity and collect lubricating oil. The design, processing, and assembly of this sealing structure are difficult, leading to increased manufacturing costs and hindering compact structural design. Meanwhile, at high speeds (such as the extreme operating conditions of aircraft engines), rubber materials may gradually age and wear, leading to a decline in sealing performance.

[0005] Existing patent application CN116123269A discloses a combined seal for high linear speed gearboxes, which relates to a shaft sealing structure. This invention addresses the problem that existing contact and non-contact seals are insufficient for the shaft sealing performance of high linear speed gearboxes, making it difficult to provide reliable sealing performance. This invention includes an oil drain nozzle, a locking nut, an oil slinger ring, a graphite sealing ring, a graphite sealing ring mounting base, an adjusting ring, an oil baffle ring, and a bearing end cover. The bearing end cover is fitted onto the outside of the rotating shaft and fixed to the gearbox bushing. The locking nut is threaded to the rotating shaft and positioned on the outside of the bearing end cover. The oil slinger ring, graphite sealing ring mounting base, adjusting ring, and oil baffle ring are sequentially arranged from the outside to the inside between the bearing end cover and the outer wall of the rotating shaft. A graphite sealing ring is embedded in the graphite sealing ring mounting base, and the oil drain nozzle is inserted into the outer end of the bearing end cover. Although this patent employs a triple seal, each seal has a potential leakage path, which may reduce the overall sealing performance, and diagnosing specific leakage sources is relatively difficult. This combination seal requires a significant amount of space in the axial direction. Summary of the Invention

[0006] This invention primarily addresses the gear shaft of a certain type of turboprop engine accessory transmission device in the prior art, used to drive external electrical accessories. Since lubricating oil is not allowed to enter these external electrical accessories, the transmission gear shaft operates at high speeds, has high output power, and requires a long service life. However, the installation space in aero-engines is limited, thus requiring high sealing performance at the gear shaft end. Existing transmission sealing devices are ill-suited to the compact structure, high linear velocity, high temperature, and long operating time of the turboprop engine gear shaft end face sealing environment. Improper sealing structure design can lead to lubricating oil leakage into the electrical accessories or affect the lubrication of parts on the gear shaft (gears and their bearings), jeopardizing the safe operation of this type of engine. This invention proposes a lubricating oil sealing structure for the engine transmission gear shaft end and an aero-engine.

[0007] An oil sealing structure for an engine drive gear shaft includes a drive gear shaft, a front bearing, a rear bearing, and an accessory housing. It also includes a sealing protection ring, a sealing assembly, a mounting base, a cover, and an oil leak nozzle. The drive gear shaft is a hollow shaft with a sealing plug in its inner bore. The sealing protection ring is fitted onto the drive gear shaft and fixedly connected by a nut. The sealing assembly, mounted on the outer circumference of the sealing protection ring, includes a stationary ring and a rotating ring. The rotating ring has annular graphite on its end face, forming a friction pair with the stationary ring. The front bearing is mounted on the accessory housing, and the rear bearing is mounted on the mounting base. An axial adjustment shim is provided at the front end of the rear bearing, and the sealing protection ring is provided at the rear end. The oil leak nozzle is located at the lower end of the accessory housing and communicates with the oil drain holes of the mounting base and the accessory housing, used to collect and monitor leaked oil. The cover is fixed to the mounting base with screws, and the mounting base is fixed to the accessory housing with nuts. Asbestos gaskets are provided between the end faces of the cover and the mounting base, and between the mounting base and the accessory housing, for sealing the end faces to prevent oil leakage.

[0008] Furthermore, the inner hole of the transmission gear shaft is provided with a triangular groove, and the sealing plug is a thin-walled structure with a wall thickness of 1mm. The claws of the sealing plug are embedded into the triangular groove by means of flaring to achieve fixation and sealing.

[0009] Furthermore, the axial adjusting shim is used to adjust the axial movement of the transmission gear shaft, and the axial movement of the transmission gear shaft is controlled within 0.1 to 0.2 mm.

[0010] Furthermore, the sealing protection ring is a thin-walled sleeve structure, with a sealing assembly installed on its outer circle to reduce the linear velocity of the sealing assembly and protect the transmission gear shaft.

[0011] Furthermore, the sealing assembly also includes a first O-ring and a second O-ring, wherein the first O-ring is mounted on the outer circumference of the stationary ring, and the second O-ring is mounted on the inner side of the rotating ring.

[0012] Furthermore, the interference fit between the second O-ring and the sealing protection ring is 0.3 to 0.5 mm. The interference fit is ensured by measuring the inner diameter of the second O-ring and selecting the outer diameter of the sealing protection ring.

[0013] Furthermore, the rotating ring is mounted on the sealing protection ring, and the second O-ring mounted inside the rotating ring is used to drive the rotating ring to rotate together with the sealing protection ring, and is also used for radial sealing; the stationary ring is mounted inside the seat cover, and the first O-ring mounted on the outer circle of the stationary ring is used for radial sealing; wherein, the stationary ring is made of magnetic material, and the rotating ring is made of rigid material, and the wear of the annular graphite is automatically compensated by magnetic attraction.

[0014] Furthermore, the threads of the nut and the transmission gear shaft are reverse threads, and the threads are opposite to the rotation direction of the transmission gear shaft. The surface is coated with thread-locking adhesive to prevent loosening.

[0015] Furthermore, the sealing assembly adopts a flexible installation method. When installing the stationary ring, pressure is applied by compressed air for a period of not less than 15 minutes. When installing the rotating ring, a small amount of grease is applied to the surface of the annular graphite. After pressing the rotating ring tightly onto the stationary ring, it is slowly rotated in one direction.

[0016] An aircraft engine employs the aforementioned oil sealing structure at the end of the engine transmission gear shaft.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention includes a transmission gear shaft, a front bearing, a rear bearing, and an accessory housing. It also includes a sealing ring, a sealing assembly, a mounting base, a cover, and an oil leak nozzle. The transmission gear shaft is a hollow shaft with a sealing plug in its inner bore. The sealing ring is fitted onto the transmission gear shaft and fixedly connected by a nut. The sealing assembly, mounted on the outer circumference of the sealing ring, includes a stationary ring and a rotating ring. The rotating ring has annular graphite on its end face, forming a friction pair with the stationary ring. The transmission gear shaft and its sealing structure of this invention operate reliably, automatically compensating for graphite wear through magnetic attraction. Simultaneously, it utilizes O-ring radial sealing and asbestos gasket end face sealing to form multiple layers of sealing protection, effectively preventing lubricating oil leakage into electrical accessories and ensuring the safe operation of the engine and electrical accessories.

[0018] 2. By designing oil passages and oil leak nozzles, the sealing performance of the sealing structure can be monitored in a timely manner during field use, and it can be easily replaced in the field. This can effectively solve the problem of adverse effects on the engine and electrical accessories when oil leakage increases or exceeds the standard.

[0019] 3. The sealing protection ring isolates the transmission gear shaft from the sealing assembly, preventing direct contact and wear between the two, thus protecting the gear shaft and the seal; secondly, the annular graphite friction pair has excellent wear resistance and magnetic attraction automatically compensates for wear, preventing overall failure due to local wear of the seal and significantly extending the service life of the sealing structure. Attached Figure Description

[0020] Figure 1 This is a diagram of the gear shaft end sealing structure of the present invention; Figure 2 This is a schematic diagram of the combined structure of the sealing plug and the transmission gear shaft of the present invention; Figure 3 This is a schematic diagram of the mounting base of the present invention; Figure 4 This is a schematic diagram of the sealing assembly structure of the present invention; Figure 5 This is a schematic diagram of the axial adjustment pad structure of the present invention; Figure 6 This is a schematic diagram of the sealing and protective ring structure of the present invention; Figure 7 This is a schematic diagram of the nut structure of the present invention; In the above figure, 1. Transmission gear shaft; 2. Sealing plug; 3. Front bearing; 4. Rear bearing; 5. Accessory housing; 6. Mounting base; 7. Axial adjustment shim; 8. Sealing protection ring; 9. Nut; 10. Mounting groove; 11. Sealing assembly; 12. Seat cover; 13. Screw; 14. Asbestos gasket; 15. Screw post; 16. Mounting base nut; 17. Asbestos gasket; 18. Oil leak nozzle; 19. Stationary ring; 20. First O-ring; 21. Rotating ring; 22. Second O-ring; 23. Annular graphite. Detailed Implementation

[0021] To clearly illustrate the technical features of the present invention, the invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can also be implemented in other ways different from those described herein; therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below. Furthermore, in the description of the invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They 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, and therefore should not be construed as a limitation of the invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. In this invention, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. In this invention, unless otherwise explicitly specified and limited, "on" or "below" a second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0022] Example 1 like Figures 1 to 7As shown, an oil sealing structure for an engine transmission gear shaft includes a transmission gear shaft 1, a front bearing 3, a rear bearing 4, and an accessory housing 5. It also includes a sealing protection ring 8, a sealing assembly 11, a mounting base 6, a cover 12, and an oil leak nozzle 18. The transmission gear shaft 1 is a hollow shaft with a sealing plug 2 in its inner hole. The sealing protection ring 8 is sleeved on the transmission gear shaft 1 and fixedly connected by a nut 9. The sealing assembly 11 is mounted on the outer circumference of the sealing protection ring 8 and includes a stationary ring 19 and a rotating ring 21. The end face of the rotating ring 21 is provided with annular graphite 23 and the stationary ring. 19. A friction pair is formed; the front bearing 3 is installed on the accessory housing 5, the rear bearing 4 is installed on the mounting base 6, the front end of the rear bearing 4 is provided with an axial adjustment pad 7, and the rear end of the rear bearing 4 is provided with a sealing protection ring 8; the oil drain nozzle 18 is located at the lower end of the accessory housing 5 and communicates with the oil drain hole of the mounting base 6 and the accessory housing 5, and is used to collect and monitor the leaked lubricating oil; the seat cover 12 is fixed to the mounting base 6 by screws 13, and the mounting base 6 is fixed to the accessory housing 5 by nuts 9; asbestos gaskets are provided between the end faces of the seat cover 12 and the mounting base 6, and between the mounting base 6 and the accessory housing 5, for sealing the end faces to prevent lubricating oil leakage.

[0023] In this embodiment, the transmission input end of the transmission gear shaft 1 of a turboprop engine driving a high-power electrical accessory is a helical gear with a rotational speed of approximately 7900 r / min, supported by two bearings at the front and rear. The output end is the transmission shaft of the electrical accessory, with a linear velocity of approximately 21 m / s on the output shaft section. The lubricating oil temperature after lubricating the gear and its bearings is approximately 115°C. To prevent lubricating oil from entering the electrical accessory, a sealing structure is designed at the shaft end of the engine accessory transmission gear shaft.

[0024] Specifically, the gear shaft sealing structure is installed at the rear end of the transmission gear shaft 1 of the engine accessory transmission component. The gear of the transmission gear shaft 1 is driven by the helical gear of the accessory transmission component, and the spline at the rear end drives the transmission shaft of the electrical accessory. To reduce the weight of the transmission gear shaft 1, the transmission gear shaft 1 is a hollow shaft. To prevent lubricating oil in the engine from flowing out of the inner hole of the transmission gear shaft 1, a sealing plug 2 is provided in the inner hole of the transmission gear shaft 1. The sealing plug has a thin-walled structure with a wall thickness of 1mm. A triangular groove is opened in the inner hole of the transmission gear shaft 1. After the thin-walled sealing plug 2 is installed in the inner hole, the claws of the thin-walled sealing plug 2 are embedded into the triangular groove by flaring, thereby achieving the purpose of sealing the lubricating oil in the inner hole.

[0025] The transmission gear shaft 1 is supported by a front bearing 3 and a rear bearing 4. The front bearing 3 and rear bearing 4 are respectively mounted on the accessory housing 5 and the mounting base 6. An axial adjustment shim 7 is provided at the front end of the rear bearing 4, used to precisely control the axial movement of the transmission gear shaft 1. A sealing ring 8 is installed at the rear end of the rear bearing 4. The sealing ring 8, rear bearing 4, and axial adjustment shim 7 are fastened to the transmission gear shaft 1 by a nut 9 at the rear end of the sealing ring 8. The thread of the nut 9 and the transmission gear shaft 1 adopts a reverse thread structure opposite to the rotation direction of the transmission gear shaft 1, and thread-locking adhesive is applied to prevent loosening during the tightening process. To prevent lubricating oil from the rear bearing 4 from leaking through the gap between the sealing ring 8 and the transmission gear shaft 1, a mounting groove 10 is provided on the transmission gear shaft 1 for installing an O-ring. Since there is no relative transmission between the sealing ring 8 and the transmission gear shaft 1 after being fastened by the nut 9, the O-ring installed on the transmission gear shaft 1 is used for radial sealing, greatly reducing the sealing space.

[0026] The sealing ring 8 is sleeved on the transmission gear shaft 1 and fastened together with the rear bearing 4 and the axial adjusting shim 7 by the nut 9. The sealing ring 8 is a sleeve-type structure, and a sealing assembly 11 is installed on its outer circle. In order to reduce the linear velocity of the sealing assembly 11, the sealing ring 8 adopts a thin-walled structure. Since there is relative movement between the transmission gear shaft 1 and the sealing assembly 11, the sealing ring 8 is set between the two. On the one hand, it protects the transmission gear shaft 1 from direct contact with the sealing assembly 11 and wear, which would lead to its failure. On the other hand, as the sealing surface wears, the sealing assembly 11 will have a certain axial movement. Therefore, it is necessary to design the sealing ring 8 to install the sealing assembly 11.

[0027] like Figure 4 As shown, the sealing assembly 11 mainly consists of a stationary ring 19, a first O-ring 20, a rotating ring 21, and a second O-ring 22. The stationary ring 19 is installed inside the seat cover 12, and the first O-ring 20, installed on the outer circumference of the stationary ring 11-1, provides radial sealing. The rotating ring 21 is installed on the sealing protection ring 8, and the second O-ring 22, installed inside the rotating ring 21, drives the rotating ring 21 to rotate with the sealing protection ring 8, while also providing radial sealing. An annular graphite 23 is embedded in the inner hole of the end face of the rotating ring 21. The annular graphite 23 and the stationary ring 19 contact each other to form a friction pair, which can withstand high-speed friction, thereby achieving a seal between the stationary ring 19 and the rotating ring 21. Since the annular graphite 23 will gradually wear down during operation, in order to ensure that the annular graphite 23 can still fit with the stationary ring 19 to form an effective friction pair after wear, the stationary ring 19 is made of magnetic material and the rotating ring 21 is made of rigid material. Relying on the magnetic attraction between the two, the wear of the annular graphite 23 is automatically compensated, thereby preventing the lubricating oil inside the engine from leaking from this part.

[0028] like Figure 3 and Figure 7 As shown, the cover 12 is fixed to the mounting base 6 by screws 13. An asbestos gasket 14 is used to seal the end faces of the cover 12 and the mounting base 6 to prevent lubricating oil from leaking between them. The mounting base 6 is fixed to the studs 15 on the accessory housing 5 by mounting base nuts 16. An asbestos gasket 17 is used to seal the end faces of the mounting base 6 and the accessory housing 5 to prevent lubricating oil from leaking between them.

[0029] The mounting base 6 has multiple oil drain holes, which are connected to the oil drain holes on the accessory housing 5, and finally connected to the oil drain nozzle 18 installed on the lower end face of the accessory housing 5. The lubricating oil leaking from the sealing assembly 11 after its sealing performance deteriorates or fails, as well as the lubricating oil leaking from other seals, flows out along the oil drain nozzle 18. Therefore, by monitoring the lubricating oil leaking from the oil drain nozzle 18, it is possible to promptly detect whether the sealing performance of the sealing structure of the engine transmission gear shaft 1 section is still effective in ensuring the normal use of the engine and electrical accessories. If the amount of lubricating oil leaking at this location increases or exceeds the standard, the relevant sealing assembly 11 or other seals should be replaced in a timely manner.

[0030] Since the transmission gear shaft 1 and related bearings 3 and 4, sealing protection ring 8, mounting base 6, sealing assembly 11, seat cover 12, etc. are fastened to the end of the accessory housing 5 by means of nuts and screws 13 and a clearance fit is adopted, it is convenient to replace parts such as sealing assembly 11, sealing protection ring 8, asbestos gasket 14, and asbestos gasket 17 on site.

[0031] The sealing structure design of the transmission gear shaft in this embodiment, through the combination of sealing plug 2, sealing protection ring 8, sealing assembly 11, mounting base 6, control of the axial movement of the gear shaft, and oil leak nozzle 18, can effectively seal the gear shaft end of the transmission electrical accessories, effectively monitor its sealing effect, and can be easily replaced on site, ensuring the normal operation of the engine and electrical accessories, and meeting the requirements of the engine in the field.

[0032] Example 2 like Figure 1As shown, an oil sealing structure for an engine transmission gear shaft includes a transmission gear shaft 1, a front bearing 3, a rear bearing 4, and an accessory housing 5. It also includes a sealing protection ring 8, a sealing assembly 11, a mounting base 6, a cover 12, and an oil leak nozzle 18. The transmission gear shaft 1 is a hollow shaft with a sealing plug 2 in its inner hole. The sealing protection ring 8 is sleeved on the transmission gear shaft 1 and fixedly connected by a nut 9. The sealing assembly 11 is mounted on the outer circumference of the sealing protection ring 8 and includes a stationary ring 19 and a rotating ring 21. The end face of the rotating ring 21 is provided with annular graphite 23 that interacts with the stationary ring 19. The components form a friction pair; the front bearing 3 is mounted on the accessory housing 5, and the rear bearing 4 is mounted on the mounting base 6. An axial adjustment pad 7 is provided at the front end of the rear bearing 4, and a sealing protection ring 8 is provided at the rear end of the rear bearing 4; the oil drain nozzle 18 is located at the lower end of the accessory housing 5 and communicates with the oil drain holes of the mounting base 6 and the accessory housing 5, and is used to collect and monitor leaked lubricating oil; the seat cover 12 is fixed to the mounting base 6 by screws 13, and the mounting base 6 is fixed to the accessory housing 5 by nuts 9; asbestos gaskets (14, 17) are provided between the end faces of the seat cover 12 and the mounting base 6, and between the mounting base 6 and the accessory housing 5, for sealing the end faces to prevent lubricating oil leakage.

[0033] In this embodiment, the installation of the sealing assembly 11 and the interference fit between the second O-ring 22 on the rotating ring 21 and the sealing protection ring 8 are important factors in ensuring that the sealing assembly 11 has good sealing performance.

[0034] like Figure 4 As shown, the sealing assembly 11 is flexibly installed. When installing the stationary ring 19, which has been fitted with the first O-ring 20, onto the seat cover 12, compressed air should be applied for at least 15 minutes to prevent the stationary ring 19 from becoming misaligned. After installation, check whether the end face of the stationary ring 19 and the end face of the seat cover 12 are in good contact. Then, install the rotating ring 21 on the stationary ring 19. The specific installation steps are as follows: First, apply a small amount of grease to the annular graphite 23 of the rotating ring 21. Then, gently place the rotating ring 21 against the stationary ring 19 and press the rotating ring 21 firmly onto the stationary ring 19 with a little force. Rotate it several times in the same direction to ensure that the annular graphite 23 and the two end faces of the stationary ring 19 are in good contact. Finally, install the sealing assembly 11 and the seat cover 12 onto the sealing protection ring 8, which is now installed onto the transmission gear shaft 1.

[0035] The second O-ring 22 on the rotating ring 21 and the sealing protection ring 8 should maintain an appropriate interference fit. If the interference fit is too large, the annular graphite 23 will not be able to effectively adhere to the stationary ring 19 after wear, causing its seal to fail. If the interference fit is too small, the sealing protection ring 8 rotating with the transmission gear shaft 1 will slip between itself and the second O-ring 22, leading to wear and failure of the second O-ring 22. Years of practical application have proven that the interference fit between the second O-ring 22 and the sealing protection ring 8 in the sealing assembly 11 on the turboprop engine transmission gear shaft 1 should be 0.3–0.5 mm. This interference fit is ensured by measuring the inner diameter of the second O-ring 22 and selecting the outer diameter of the sealing protection ring 8. This ensures that the rotating ring 21 can rotate reliably with the shaft while reserving sufficient axial movement space for wear compensation, preventing premature wear or jamming of the O-ring.

[0036] This embodiment significantly improves the durability and stability of the sealing structure and reduces the maintenance frequency through magnetic compensation, precise interference control, and meticulous installation process, making it particularly suitable for long-life, high-reliability aero-engine applications.

[0037] Example 3 like Figure 1 As shown, in this embodiment, the transmission gear shaft 1 must have a certain amount of axial movement. If this axial movement is too small, the bearing 3 or bearing 4 will easily form angular contact due to thermal expansion during operation, leading to increased local stress and wear failure. If the axial movement is too large, it will increase the axial movement of the sealing assembly 11, which is detrimental to the sealing. Years of practical application have proven that the axial movement of the turboprop engine transmission gear shaft 1 should be 0.1–0.2 mm, which is ensured by selecting an axial adjustment shim 7.

[0038] Any lubricating oil that may leak from the sealing assembly 11, the gap between the sealing ring 8 and the drive shaft, etc., will be collected by the drainage channels in the mounting base 6 and the accessory housing 5, and finally discharged from the oil drain nozzle 18. Ground personnel can intuitively and effectively judge the health status of the sealing structure by simply observing the lubricating oil leakage at the oil drain nozzle 18 (such as the frequency or flow rate) without disassembling any parts, thus achieving preventive maintenance. In this embodiment, the entire sealing structure (including the transmission gear shaft 1, bearing, sealing protection ring 8, sealing assembly 11, mounting base 6, and seat cover 12) is modularly installed at the end of the accessory housing 5 using standard fasteners such as nuts 9 and screws 13, with clearance fits used in key mating parts. This allows vulnerable parts such as the sealing assembly 11, sealing protection ring 8, O-rings, and asbestos gaskets (14, 17) to be easily and quickly replaced under field conditions, greatly improving engine maintainability and shortening downtime.

[0039] Obviously, the embodiments described above are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An oil sealing structure for the end of an engine transmission gear shaft, comprising a transmission gear shaft, a front bearing, a rear bearing, and an accessory housing, characterized in that, It also includes a sealing protection ring, a sealing assembly, a mounting base, a seat cover, and an oil leak nozzle. The transmission gear shaft is a hollow shaft with a sealing plug in its inner hole. The sealing protection ring is sleeved on the transmission gear shaft and fixedly connected by a nut. The sealing assembly is installed on the outer circle of the sealing protection ring and includes a stationary ring and a rotating ring. The end face of the rotating ring has annular graphite to form a friction pair with the stationary ring. The front bearing is installed on the accessory housing, and the rear bearing is installed on the mounting base. An axial adjustment shim is provided at the front end of the rear bearing, and a sealing protection ring is provided at the rear end. The oil leak nozzle is located at the lower end of the accessory housing and communicates with the oil drain hole of the mounting base and the accessory housing for collecting and monitoring leaked lubricating oil. The seat cover is fixed to the mounting base with screws, and the mounting base is fixed to the accessory housing with nuts. Asbestos gaskets are provided between the end faces of the seat cover and the mounting base, and between the mounting base and the accessory housing, for sealing the end faces to prevent lubricating oil leakage.

2. The lubricating oil sealing structure at the end of an engine transmission gear shaft according to claim 1, characterized in that, The transmission gear shaft has a triangular groove in its inner hole. The sealing plug is a thin-walled structure with a wall thickness of 1mm. The claws of the sealing plug are embedded into the triangular groove by flaring to achieve fixation and sealing.

3. The lubricating oil sealing structure at the end of the engine transmission gear shaft according to claim 1, characterized in that, The axial adjustment shim is used to adjust the axial movement of the transmission gear shaft, and the axial movement of the transmission gear shaft is controlled within 0.1 to 0.2 mm.

4. The lubricating oil sealing structure at the end of an engine transmission gear shaft according to claim 1, characterized in that, The sealing protection ring is a thin-walled sleeve structure, with a sealing assembly installed on its outer circle to reduce the linear velocity of the sealing assembly and protect the transmission gear shaft.

5. The lubricating oil sealing structure at the end of an engine transmission gear shaft according to claim 1, characterized in that, The sealing assembly further includes a first O-ring and a second O-ring, wherein the first O-ring is installed on the outer circumference of the stationary ring, and the second O-ring is installed on the inner side of the rotating ring.

6. The oil sealing structure at the end of an engine transmission gear shaft according to claim 5, characterized in that, The interference fit between the second O-ring and the sealing protection ring is 0.3 to 0.5 mm. The interference fit is ensured by measuring the inner diameter of the second O-ring and selecting the outer diameter of the sealing protection ring.

7. The oil sealing structure at the end of an engine transmission gear shaft according to claim 5, characterized in that, The rotating ring is mounted on the sealing protection ring, and the second O-ring mounted inside the rotating ring is used to drive the rotating ring to rotate together with the sealing protection ring, and also for radial sealing; the stationary ring is mounted inside the seat cover, and the first O-ring mounted on the outer circle of the stationary ring is used for radial sealing; wherein, the stationary ring is made of magnetic material, and the rotating ring is made of rigid material, and the wear of the annular graphite is automatically compensated by magnetic attraction.

8. The lubricating oil sealing structure at the end of an engine transmission gear shaft according to claim 1, characterized in that, The nut and the drive gear shaft have a reverse thread structure, which is opposite to the rotation direction of the drive gear shaft, and the surface is coated with thread-locking adhesive to prevent loosening.

9. The lubricating oil sealing structure at the end of an engine transmission gear shaft according to claim 1, characterized in that, The sealing assembly adopts a flexible installation method. When installing the stationary ring, pressure is applied by compressed air for a period of not less than 15 minutes. When installing the rotating ring, a small amount of grease is applied to the surface of the annular graphite. After pressing the rotating ring tightly onto the stationary ring, it is slowly rotated in one direction.

10. An aircraft engine, characterized in that, The engine transmission gear shaft end lubricating oil sealing structure described in any one of claims 1 to 9 is adopted.

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