High sealing reliability of aero-engine lubricating oil ventilation system

Abstract

The application belongs to the field of aero-engines, and particularly relates to a high sealing reliability aero-engine lubricating oil ventilation system. The thickness of the front and middle oil return stage rotors in the oil return pump set is increased, the oil return capacity of the front and middle oil return stages is increased, the oil return effect of the bearing cavity is improved, and oil leakage is avoided. Controllable ventilation electromagnetic valves are arranged in the ventilation pipelines of the front and middle bearing cavities. When the engine is at a low speed, the front and middle cavities are closed for ventilation. Under the suction of the oil return pump set, the cavity pressure of the front and middle cavities is reduced, the sealing pressure difference is increased, the sealing reliability is improved, and oil leakage of the front and middle cavities is avoided.

Description

A high-sealing-reliability aircraft engine lubricating oil ventilation system Technical Field

[0001] This application belongs to the field of aero-engines, and specifically relates to a high-sealing-reliability aero-engine lubricating oil ventilation system. Background Technology

[0002] High-temperature and high-speed operating conditions place high demands on the working environment of aero-engine bearings, thus requiring lubricating oil to remove the heat generated by the high-speed rotation and friction of the bearings. To prevent lubricating oil leakage within the bearing cavity, a lubricating oil bleed ventilation system must be designed to ensure sufficient sealing pressure differential. A typical aero-engine lubricating oil ventilation system comprises three bearing cavities: the front bearing cavity, the middle bearing cavity, and the rear bearing cavity. The lubricating oil tank cavity is connected to the accessory casing cavity. The lubricating oil return system uses a return oil pump set to draw the oil-gas mixture from the front, middle, and rear bearing cavities back to the lubricating oil return pipeline, where it passes through an oil-gas separator and enters the lubricating oil tank cavity. The lubricating oil ventilation system mainly includes two flow paths: the bleed airflow path and the lubricating oil ventilation path. When the engine is at a low speed, low-pressure gas flows into the bearing cavity through the bleed air pipe and flows out of the bearing cavity through the ventilation pipe. However, the gas pressure introduced by the traditional bleed air system changes with the engine speed, so the difference between the bleed air pressure and the bearing cavity pressure cannot be kept in an ideal state. This results in a low sealing pressure difference between the front and middle bearing cavities, which cannot meet the sealing requirements and leads to lubricating oil leakage. The return oil pump set has a low return oil capacity and a weak ability to suck oil and gas in the bearing cavity, which affects the oil and gas extraction effect in the bearing cavity and may also lead to lubricating oil leakage. Summary of the Invention

[0003] To address the aforementioned issues, this application provides a high-sealing-reliability aero-engine lubricating oil ventilation system for providing a sealing pressure differential to the aero-engine bearing cavity. The bearing cavity includes a front bearing cavity, a middle bearing cavity, and a rear bearing cavity. The front bearing cavity and the middle bearing cavity employ a contact seal, which improves the airtightness of the bearing cavity by closing the pipeline. The rear bearing cavity employs a non-contact seal, which will leak air when its ventilation pipeline is closed.

[0004] The features are as follows: the front bearing cavity, the middle bearing cavity, and the rear bearing cavity are respectively connected to bleed air pipes; the bleed air pipes introduce engine gas into the front bearing cavity, the middle bearing cavity, and the rear bearing cavity respectively; the front bearing cavity is connected to a first lubricating oil cavity ventilation path for exhaust, the middle bearing cavity is connected to a second lubricating oil cavity ventilation path for exhaust, and the rear bearing cavity is connected to a third lubricating oil cavity ventilation path for exhaust; the first lubricating oil cavity ventilation path is connected to the second lubricating oil cavity ventilation path and then to the third lubricating oil cavity ventilation path to form a main lubricating oil cavity ventilation path; the main lubricating oil cavity ventilation path leads into the accessory gearbox cavity, the accessory gearbox cavity has a centrifugal ventilator and a high-altitude valve for exhausting gas; the main lubricating oil cavity ventilation path has a ventilation valve;

[0005] After the first lubricating oil chamber ventilation passage and the second lubricating oil chamber ventilation passage are connected, there is a ventilation solenoid valve before the main lubricating oil chamber ventilation passage; when the engine speed is lower than the preset value, the solenoid valve is closed, and when the engine speed is higher than the preset value, the solenoid valve is opened.

[0006] The middle bearing cavity and the rear bearing cavity are respectively connected to the lubricating oil return line. The lubricating oil return line is connected to the return oil pump group for sucking the oil-gas mixture in the lubricating oil return line. The return oil pump group sends the sucked oil-gas mixture into the oil-gas separator. The oil-gas separator sends the separated oil into the lubricating oil tank.

[0007] Preferably, the bleed air line introduces gas from the engine fan into the front bearing cavity, the middle bearing cavity, and the rear bearing cavity, respectively.

[0008] Preferably, a ventilation throttling nozzle is installed on the ventilation path of the first lubricating oil chamber.

[0009] Preferably, a pressure sensor is installed on the solenoid valve, and the opening degree of the solenoid valve is controlled by the pressure value of the pressure sensor to keep the air pressure in the front bearing cavity and the middle bearing cavity within a preset range.

[0010] Preferably, the return oil pump group includes multiple return oil pumps, and pressure sensors and their corresponding return oil pumps are respectively installed in the front bearing cavity, the middle bearing cavity and the rear bearing cavity. Each return oil pump controls the power of pumping into the corresponding bearing cavity according to the pressure signal of the pressure sensor of its corresponding bearing cavity.

[0011] The advantages of this application include: increasing the thickness of the rotors in the front and middle chambers of the return oil pump group improves the return oil capacity of the return oil stages in the front and middle chambers; by setting a ventilation solenoid valve in the ventilation convergence path of the front bearing cavity and the middle bearing cavity, when the engine is at a low speed, the ventilation solenoid valve is in the closed state, that is, the ventilation of the front bearing cavity and the middle bearing cavity is closed, and the pressure in the front bearing cavity and the middle bearing cavity reaches a low level through the suction action of the return oil pump group, thereby increasing the sealing pressure difference; when the engine is at a higher speed, the ventilation solenoid valve is in the open state, and the front bearing cavity and the middle bearing cavity resume throttling ventilation. Since the front bearing cavity is small in volume, adding a ventilation throttling nozzle or blocking the front cavity ventilation path allows the return oil stage in the front chamber of the return oil pump group to draw more oil and gas in the front bearing cavity, further reducing the pressure in the front bearing cavity, increasing the sealing pressure difference in the front cavity, and preventing lubricating oil leakage from the front and middle bearing cavities. Attached Figure Description

[0012] Figure 1 is a schematic diagram of a lubricating oil ventilation system according to a preferred embodiment of this application. Detailed Implementation

[0013] 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. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0014] As shown in Figure 1, specifically: the thickness of the rotor of the front and middle chamber return oil stage of the return oil pump group 1 is increased to increase the return oil capacity of the front and middle chamber return oil stages of the return oil pump group.

[0015] When the engine is at a low speed, the bleed air pressure is low, the ventilation valve 5 is in a throttling ventilation state, and the ventilation solenoid valve 7 is in the closed state. Low-pressure gas flows into the front bearing cavity A, the middle bearing cavity B, and the rear bearing cavity C through the bleed air pipeline. The ventilation pipeline of the front bearing cavity A is equipped with a ventilation throttle nozzle 6. Under the suction action of the oil return stage in the front cavity of the oil return pump group 1, the oil-gas mixture flows through the oil return pipeline in the front cavity and passes through the oil-gas separator 4 into the lubricating oil tank D. Under the suction action of the oil return stage in the middle cavity of the oil return pump group 1, the oil-gas mixture flows through the oil return pipeline in the middle cavity and passes through the oil-gas separator 4 into the lubricating oil tank D. Some of the gas in the middle bearing cavity B flows to the accessory housing E through a bottom ventilation pipeline. The ventilation gas in the rear bearing cavity C flows to the accessory housing E through the ventilation valve 5. The above ventilation gases converge in the accessory housing E and are then discharged from the engine through the centrifugal ventilator 3 and the high-altitude valve 2.

[0016] When the engine is at a higher speed, the bleed air pressure is higher, the ventilation valve 5 is in a free ventilation state, and the ventilation solenoid valve 7 is in the open state. High-pressure gas flows into the front bearing cavity A, the middle bearing cavity B, and the rear bearing cavity C through the bleed air pipeline. A ventilation throttle nozzle 6 is added to the ventilation pipeline of the front bearing cavity A. Under the suction of the return oil stage in the front cavity of the return oil pump group 1, the oil-gas mixture flows through the return oil pipeline of the front cavity, passes through the oil-gas separator 4, and enters the lubricating oil tank D. Part of the gas in the middle bearing cavity B flows to the accessory housing E through a bottom ventilation pipeline. Part of the gas, under the suction of the return oil stage in the middle cavity of the return oil pump group 1, flows through the return oil pipeline of the middle cavity, passes through the oil-gas separator 4, and enters the lubricating oil tank D. Part of the gas merges with the ventilation gas flowing out of the rear bearing cavity C through the ventilation solenoid valve 7 and flows to the accessory housing E through the ventilation valve 5. After merging in the accessory housing E, the above ventilation gases are discharged from the engine through the centrifugal ventilator 3 and the high-altitude valve 2.

[0017] This results in a higher bearing cavity sealing pressure differential (the difference between the bleed air pressure and the bearing cavity pressure), preventing oil leakage in the bearing cavity and improving the sealing reliability of the aero-engine oil ventilation system.

[0018] Implementation example:

[0019] After increasing the rotor thickness of the front and middle chamber return stages of the oil return pump unit 1, the return capacity of the front and middle chambers is increased by 50% and 20%, respectively. After adding ventilation solenoid valves 7 to the ventilation pipes of the front bearing cavity A and the middle bearing cavity B, and adding ventilation throttle nozzles 6 to the ventilation pipe of the front bearing cavity A, the sealing pressure difference between the front and middle chambers increases by 5.4 times and 2.4 times, respectively, when the engine is at a low speed. The sealing reliability of the lubricating oil ventilation system is significantly improved, effectively avoiding lubricating oil leakage problems caused by insufficient sealing pressure difference.

[0020] Compared with the prior art, the main advantages of the present invention are:

[0021] 1. By increasing the thickness of the rotor in the front and middle chambers of the return oil pump group, the return oil capacity of the front and middle chambers is increased, the return oil effect of the bearing cavity is improved, and lubricating oil leakage is avoided.

[0022] 2. By installing controllable ventilation solenoid valves in the ventilation pipes of the front and middle bearing cavities, when the engine is at a low speed, the ventilation of the front and middle cavities is closed. Under the suction action of the return oil pump group, the pressure in the front and middle cavities is reduced, the sealing pressure difference is increased, the sealing reliability is increased, and the lubricating oil leakage in the front and middle cavities is avoided.

[0023] 3. By adding a ventilation throttle nozzle to the ventilation pipe of the front bearing cavity, the pressure in the front bearing cavity is further reduced, the sealing pressure difference of the front cavity is increased, and the lubricating oil leakage in the front cavity is avoided.

[0024] 4. Equipped with a pressure sensor, it can infinitely adjust the pressure inside the bearing cavity.

[0025] 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 high-sealing-reliability lubricating oil ventilation system for an aero-engine, used to provide a sealing pressure differential to the bearing cavity of an aero-engine, the bearing cavity including a front bearing cavity (A), a middle bearing cavity (B), and a rear bearing cavity (C), wherein the front bearing cavity (A) and the middle bearing cavity (B) are sealed by contact, and the rear bearing cavity (C) is sealed by non-contact; characterized in that, The front bearing cavity (A), the middle bearing cavity (B) and the rear bearing cavity (C) are respectively connected to the bleed air pipeline; the bleed air pipeline introduces the engine gas into the front bearing cavity (A), the middle bearing cavity (B) and the rear bearing cavity (C) respectively; the front bearing cavity (A) is connected to the first lubricating oil cavity ventilation path for exhaust, the middle bearing cavity (B) is connected to the second lubricating oil cavity ventilation path for exhaust, and the rear bearing cavity (C) is connected to the third lubricating oil cavity ventilation path for exhaust. The first lubricating oil cavity ventilation path is connected to the second lubricating oil cavity ventilation path and then connected to the third lubricating oil cavity ventilation path to form the main lubricating oil cavity ventilation path. The main lubricating oil cavity ventilation path leads into the accessory casing cavity (E). The accessory casing cavity (E) has a centrifugal ventilator (3) and a high-altitude valve (2) for exhausting gas. The main lubricating oil chamber ventilation path has a ventilation valve (5); after the first lubricating oil chamber ventilation path and the second lubricating oil chamber ventilation path are connected, and before the main lubricating oil chamber ventilation path, there is a ventilation solenoid valve (7), which is located in the ventilation convergence path of the front bearing chamber and the middle bearing chamber; when the engine speed is lower than the preset value, the solenoid valve (7) is closed, and when the engine speed is higher than the preset value, the solenoid valve (7) is opened; the middle bearing chamber (B) and the rear bearing chamber (C) are respectively connected to the lubricating oil return path, and the lubricating oil return path is connected to the return oil pump group (1) for sucking the oil-gas mixture in the lubricating oil return path. The return oil pump group (1) sends the sucked oil-gas mixture into the oil-gas separator (4), and the oil-gas separator (4) sends the separated oil into the lubricating oil tank (D).

2. The high sealing reliability aero-engine lubricating oil ventilation system as described in claim 1, characterized in that, The bleed air line introduces gas from the engine fan into the front bearing chamber (A), the middle bearing chamber (B), and the rear bearing chamber (C), respectively.

3. The high sealing reliability aero-engine lubricating oil ventilation system as described in claim 1, characterized in that, A ventilation throttling nozzle (6) is installed on the ventilation path of the first lubricating oil chamber.

4. The high sealing reliability aero-engine lubricating oil ventilation system as described in claim 1, characterized in that, A pressure sensor is installed on the solenoid valve (7). The opening degree of the solenoid valve (7) is controlled by the pressure value of the pressure sensor, so that the air pressure in the front bearing cavity (A) and the middle bearing cavity (B) is kept within a preset range.

5. The high sealing reliability aero-engine lubricating oil ventilation system as described in claim 1, characterized in that, The return oil pump group (1) includes multiple return oil pumps. Pressure sensors and their corresponding return oil pumps are installed in the front bearing cavity (A), the middle bearing cavity (B) and the rear bearing cavity (C). Each return oil pump controls the power of pumping the corresponding bearing cavity according to the pressure signal of the pressure sensor of its corresponding bearing cavity.

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