A bearing cavity ventilation structure and a structure for reducing flow resistance of a bearing cavity ventilation pipe

Abstract

The application provides a structure for reducing the flow resistance of a bearing cavity ventilation pipe, wherein the ventilation pipe is configured with an oil blocking structure protruding from the bearing cavity wall surface by a predetermined distance at one end of the ventilation pipe extending into the bearing cavity, the oil blocking structure is used for blocking the lubricating oil of the bearing cavity wall surface from entering the ventilation pipe along the ventilation air, and the lubricating oil of the bearing cavity wall surface cannot enter the ventilation pipe by gravity after being blocked. The scheme provided by the application significantly reduces the lubricating oil entering the ventilation pipe, significantly reduces the flow resistance of the ventilation pipe without increasing the diameter of the ventilation pipe, is beneficial to reducing the pressure of the bearing cavity, improves the sealing pressure difference under the condition that the sealing induced air pressure is the same, and prevents lubricating oil leakage.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a bearing cavity ventilation structure and a structure for reducing the flow resistance of the bearing cavity ventilation pipe. Background Technology

[0002] The bearing cavity of an aircraft engine is a cavity that houses the rotor pivot bearing of the engine. Its main functions are to isolate the bearing from the high-temperature environment, collect and recycle the lubricating oil used for bearing lubrication, and prevent the lubricating oil from leaking from the bearing cavity to the outside of the engine by sealing it with air.

[0003] To prevent lubricating oil from leaking out of the engine through the sealing structure between the rotor and stator, a bleed air stream is typically introduced into the bearing cavity via a sealing device and then discharged through a ventilation pipe. The greater the difference between the bleed air pressure and the bearing cavity pressure (hereinafter referred to as the sealing pressure difference), the better the sealing effect. During engine start-up or shutdown, due to the low engine speed, the bleed air pressure is also at a low level. To ensure that the sealing pressure difference of the bearing cavity meets the sealing requirements, it is generally necessary to reduce the resistance of the ventilation pipe, thereby reducing the bearing cavity pressure.

[0004] Based on current engine testing experience, the bearing cavity environment is a two-phase flow state of oil and gas. The ventilator in the ventilation pipe carries a large amount of lubricating oil, which will lead to poor ventilation in the engine bearing cavity. Especially at low conditions, this will further reduce the sealing pressure difference, causing bleed air and lubricating oil leakage, which will affect engine safety.

[0005] To reduce the flow resistance of aero-engine ventilation ducts and increase the sealing pressure differential, the current approach is to increase the diameter of the ventilation ducts. However, increasing the diameter of the ventilation ducts leads to an increase in engine weight, which does not meet the engine design goals. Therefore, a ventilation duct with a simple structure and light weight is needed. Summary of the Invention

[0006] The purpose of this application is to provide a bearing cavity ventilation structure and a structure for reducing the flow resistance of the bearing cavity ventilation pipe, so as to solve or alleviate at least one of the problems in the prior art.

[0007] The technical solution of this application is: a structure for reducing the flow resistance of a bearing cavity ventilation pipe, wherein the ventilation pipe is configured to have an oil-blocking structure at one end of the ventilation pipe that extends into the bearing cavity at a predetermined distance above the bearing cavity wall. The oil-blocking structure is used to prevent the lubricating oil on the bearing cavity wall from entering the ventilation pipe with the ventilation air, and the lubricating oil on the bearing cavity wall is blocked and drips down by gravity and cannot enter the ventilation pipe.

[0008] Furthermore, the distance by which the oil-blocking structure protrudes above the bearing cavity wall is greater than the thickness of the oil film adhering to the bearing cavity wall.

[0009] In addition, this application also provides a bearing cavity ventilation structure, the bearing cavity ventilation structure comprising:

[0010] The bearing cavity is formed by the bearing housing;

[0011] The engine main shaft is located inside the bearing cavity;

[0012] A sealed runway and bearing are supported on the main shaft of the engine. The sealed runway is equipped with a sealing device. The sealing force is led to the sealing device to seal the bearing cavity. The inner and outer rings of the bearing are respectively supported and installed on the engine bearing and the bearing cavity housing.

[0013] An oil supply pipe extends through the bearing housing into the bearing cavity, and an oil nozzle is provided at the end of the oil supply pipe, the oil nozzle being adapted to the inner ring of the bearing;

[0014] A ventilation pipe extends through the bearing housing into the bearing cavity. At the end of the ventilation pipe extending into the bearing cavity, an oil-blocking structure extends a predetermined distance above the bearing cavity wall. This oil-blocking structure prevents lubricating oil from the bearing cavity wall from entering the ventilation pipe with the ventilation air, and the blocked lubricating oil drips off due to gravity, preventing it from entering the ventilation pipe.

[0015] The oil return pipe is located at the lower end of the bearing housing.

[0016] Furthermore, the distance by which the oil-blocking structure protrudes above the bearing cavity wall is greater than the thickness of the oil film adhering to the bearing cavity wall.

[0017] The solution provided in this application significantly reduces the amount of lubricating oil entering the ventilation pipe, thereby significantly reducing the flow resistance of the ventilation pipe without increasing its diameter. This helps to reduce the bearing cavity pressure, increase the sealing pressure difference under the same sealing venting pressure, and prevent lubricating oil leakage. Attached Figure Description

[0018] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0019] Figure 1 This is a schematic diagram of a traditional bearing cavity ventilation structure.

[0020] Figure 2 This is a schematic diagram of the lubricating oil movement in a traditional bearing cavity ventilation structure.

[0021] Figure 3 This is a schematic diagram of the lubricating oil distribution inside a traditional ventilation duct.

[0022] Figure 4 This is a schematic diagram of the ventilation duct structure and its internal lubricating oil distribution in this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0024] like Figure 1 The diagram shows a traditional bearing cavity and ventilation pipe structure. The bearing cavity 10 contains an engine main shaft 11. A sealing runway 12 is mounted on the engine main shaft 11, and a sealing device 13 is installed on the sealing runway 12. A sealing bleed air 131 is introduced into the sealing device 13 to seal the bearing cavity 10 on its left side. A bearing 14 is mounted on the left end of the engine main shaft 11. The inner ring 141 of the bearing 14 mates with the engine main shaft 11, and the outer ring 142 mates with the stator. An oil supply pipe 15 passes through the stator and extends into the bearing cavity 10, with a nozzle 151 spraying oil onto the inner ring 141 of the bearing. A ventilation pipe 20 is installed at the upper end of the stator facing the bearing 14, through which ventilation air 21 flows out of the bearing cavity 10. A return oil pipe 16 is installed at the lower end of the stator facing the bearing 14, through which the lubricating oil in the bearing cavity 10 returns to the oil supply line.

[0025] During operation, the pressure of the sealing bleed air 131 is greater than the pressure of the bearing cavity 10. The sealing bleed air 131 enters the bearing cavity 10 through the sealing device 13 to prevent lubricating oil leakage at the mating surface (sealed runway) between the engine main shaft 11 and the stator (bearing cavity housing). The mixture of lubricating oil and sealing air will be discharged from the bearing cavity 10 through the ventilation pipe 20.

[0026] When the lubricating oil content in the ventilation gas 21 is too high, the high viscosity of the lubricating oil makes it difficult to flow, which will reduce the ventilation area of ​​the ventilation pipe and hinder the smooth discharge of the ventilation gas. This will cause the pressure in the bearing cavity 10 to increase, and under the condition that the sealing priming pressure is constant, the sealing pressure difference will decrease accordingly.

[0027] There are two main ways in which lubricating oil enters the ventilation pipe 21:

[0028] 1) Lubricating oil supplied to bearing 14 through lubricating oil nozzle 151, a small amount of which is thrown into ventilation pipe 21 by the rotation of bearing 12, such as... Figure 2 As shown;

[0029] 2) A large amount of lubricating oil adheres to the inner wall of the bearing cavity through the rotating oil-throwing action of the inner ring 141, and has the same tangential velocity as the bearing rotation direction. This causes a large amount of lubricating oil 23 adhering around the ventilation pipe 20 to flow into the ventilation pipe 20 with the ventilation air, such as... Figure 3 As shown.

[0030] To reduce the flow resistance of ventilation ducts, the traditional method is to increase the inner diameter of the ventilation duct. However, increasing the diameter allows more lubricating oil to enter the ventilation duct, thus the reduction in resistance is not significant. Instead, it greatly increases the weight of the ventilation duct, which has an adverse effect on the engine. Therefore, this application provides a structure to prevent lubricating oil on the ventilation wall from entering the ventilation duct with the airflow.

[0031] like Figure 4 As shown, the structure for reducing the flow resistance of the bearing cavity ventilation pipe provided in this application mainly lies in the improvement of the ventilation pipe. The ventilation pipe 30 extends into the bearing cavity 1 and is higher than the bearing cavity wall by a certain distance, thereby forming an oil-blocking structure 31. The height of the oil-blocking structure 31 above the bearing cavity wall is greater than the thickness of the oil film adhering to the bearing cavity wall. At this time, the lubricating oil on the bearing cavity wall is blocked and drips down by gravity, and cannot enter the ventilation pipe 30.

[0032] The solution provided in this application significantly reduces the amount of lubricating oil entering the ventilation pipe, thereby significantly reducing the flow resistance of the ventilation pipe without increasing its diameter. This helps to reduce the bearing cavity pressure, increase the sealing pressure difference under the same sealing venting pressure, and prevent lubricating oil leakage.

[0033] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A bearing cavity ventilation structure, characterized in that, The bearing cavity ventilation structure includes: The bearing cavity is formed by the bearing housing. The engine main shaft is located inside the bearing cavity; A sealed runway and bearing are supported on the main shaft of the engine. The sealed runway is equipped with a sealing device. The sealing force is led to the sealing device to seal the bearing cavity. The inner and outer rings of the bearing are respectively supported and installed on the engine bearing and the bearing cavity housing. An oil supply pipe extends through the bearing housing into the bearing cavity, and an oil nozzle is provided at the end of the oil supply pipe, the oil nozzle being adapted to the inner ring of the bearing; A ventilation pipe extends through the bearing housing into the bearing cavity. At the end of the ventilation pipe extending into the bearing cavity, an oil-blocking structure extends a predetermined distance above the bearing cavity wall. This oil-blocking structure prevents lubricating oil from the bearing cavity wall from entering the ventilation pipe with the ventilation air, and the blocked lubricating oil drips off due to gravity, preventing it from entering the ventilation pipe. The oil return pipe is located at the lower end of the bearing housing.

2. The bearing cavity ventilation structure as described in claim 1, characterized in that, The distance between the oil-blocking structure and the bearing cavity wall is greater than the thickness of the oil film adhering to the bearing cavity wall.

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