Bearing sealing system for aero-engine under all working conditions

Abstract

The invention belongs to the field of aero-engine design, and particularly relates to a bearing sealing system for an aero-engine under full working conditions, which comprises a first air entraining pipe, a second air entraining pipe, an air entraining conveying pipe and an air outlet pipe, the output end of the first air entraining pipe and the output end of the second air entraining pipe are connected with different middle stages of the air compressor respectively, the first air entraining pipe is connected with a one-way valve, and the second air entraining pipe is connected with a control valve. Switching of different air entraining positions is achieved through a switch valve for controlling the flow capacity of an air entraining pipe of an air compressor, when an engine is in a low state, the valve is in an open state, high-pressure air is entrained from the air compressor to seal a bearing, and when the engine is in a high state, the valve is in a closed state, and low-pressure air is entrained from the air compressor to seal the bearing; the problem that the large-state pressure and temperature exceed the limit or the small-state pressure is insufficient due to the fact that an air entraining structure is fixed in a conventional scheme can be solved.

Description

Technical Field

[0001] This application belongs to the field of aero-engine design, and specifically relates to a bearing sealing system for aero-engines under all operating conditions. Background Technology

[0002] Existing conventional sealing solutions involve designing bearing seals based on the engine's design point conditions. This involves bleed air from the compressor's intermediate stage, channeling it through bleed pipes to the front, middle, and rear bearing cavities. Adjustments to the bleed air position, pipe diameter, and bearing cavity pressure ensure the bearing cavities operate under suitable conditions at the design point. Then, full-condition verification and evaluation are performed. While this design is relatively simple and rapid, suitable for quick iterations of the overall engine design in its initial stages, it lacks adjustment mechanisms. Within the engine's full envelope, issues such as insufficient pressure differential at idle and high-altitude upper boundary seals, excessive pressure differential at the lower right node seals, and excessively high right boundary seal temperatures often arise, leading to the solution failing to meet sealing requirements.

[0003] Bleed air source switching scheme: Some engine designs employ a three-way control valve structure, simultaneously inputting bleed air from two positions adjusting different flight states and outputting it to the bearing sealing position. The valve design for controlling the bleed air source switching has high requirements, needing to simultaneously handle high-pressure, high-temperature and low-pressure, low-temperature gases. Therefore, the control valve needs to be custom-designed according to the bleed air source requirements, lacking versatility. The control valve only has the function of switching bleed air sources; it cannot control the flow rate by adjusting the throttling area of ​​the bleed air pipe or add control valves to different bleed air source pipes, greatly increasing costs and the complexity of the control logic. Furthermore, control valve failure can cause lubricating oil leakage or high-temperature gas entering the bearing cavity, leading to lubricating oil coking or even fire, seriously affecting the normal operation of the engine.

[0004] Bearing cavity exhaust control scheme: In some engines where bleed air cannot be adjusted, a control valve is installed in the bearing cavity ventilation pipe to regulate the bearing cavity pressure. Based on the engine bleed air pressure and sealing requirements, the flow area of ​​the bearing cavity exhaust pipe is adjusted by controlling the valve to change the bearing cavity exhaust resistance, thereby obtaining a suitable sealing pressure difference to meet the sealing requirements. Although this control scheme can effectively reduce the problem of excessive sealing pressure difference caused by the engine under high conditions, the control scheme fails when the bleed air pressure is too low, and it cannot control the sealing temperature.

[0005] Therefore, how to achieve more effective sealing control is a problem that needs to be solved. Summary of the Invention

[0006] The purpose of this application is to provide a bearing sealing system for aero-engines under all operating conditions, in order to solve the problem that the sealing pressure of existing sealing designs is difficult to meet the requirements.

[0007] The technical solution of this application is: a bearing sealing system for an aero-engine under all operating conditions, including a first bleed air pipe, a second bleed air pipe, a bleed air delivery pipe, and an exhaust pipe; the output ends of the first bleed air pipe and the second bleed air pipe are respectively connected to different intermediate stages of the compressor; a one-way valve is connected to the first bleed air pipe, and a control valve is connected to the second bleed air pipe; the positive direction of the one-way valve is towards the intermediate stage of the compressor;

[0008] The input end of the air delivery pipe is connected to the output ends of the first and second air delivery pipes, and the output end is connected to the air outlet pipe, which is connected to the sealing cavity of the central bearing.

[0009] Preferably, the sealing cavity of the intermediate bearing is provided with a bearing sealing device, a first air bleed sealing device is provided between the first air bleed pipe and the intermediate stage of the compressor, and a second air bleed sealing device is provided between the second air bleed pipe and the intermediate stage of the compressor.

[0010] Preferably, the second air intake tube is located behind the first air intake tube, and the air intake pressure of the second air intake tube at the outlet of the first air intake tube is greater than the air intake pressure of the first air intake tube itself at the outlet; when the control valve is opened, the one-way valve is closed.

[0011] Preferably, when the compressor intermediate stage bleed air enters the first and second bleed air pipes when the engine is just started and reaches idle speed, the pressure difference of the bleed air delivered to the sealing chamber of the intermediate bearing is greater than or equal to the sealing pressure difference.

[0012] Preferably, when the control valve switches states, if the pressure or temperature of the second bleed pipe exceeds the sealing limit, the bleed air entering the second bleed pipe from any position in the intermediate stage of the compressor enters the sealing cavity of the intermediate bearing, and the pressure difference of the bleed air in the intermediate cavity meets the sealing requirements.

[0013] Preferably, the control valve is a mechanical valve, which is equipped with a pressure threshold and a temperature threshold. When the temperature of the corresponding intermediate stage of the compressor is greater than the temperature threshold or the pressure of the corresponding intermediate stage of the compressor is greater than the pressure threshold, the control valve opens.

[0014] This application discloses a bearing sealing system for an aero-engine under all operating conditions. By controlling the opening and closing valve of the compressor bleed air pipe, different bleed air positions can be switched. When the engine is in a low-pressure state, the valve is open, drawing high-pressure air from the compressor to seal the bearing. When the engine is in a high-pressure state, the valve is closed, drawing low-pressure air from the compressor to seal the bearing. This solves the problems of excessive pressure and temperature under high-pressure conditions or insufficient pressure under low-pressure conditions caused by the fixed bleed air structure in conventional solutions. Attached Figure Description

[0015] 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.

[0016] Figure 1 This is a schematic diagram of the overall structure of this application.

[0017] 1. First air intake pipe; 2. Second air intake pipe; 3. Air delivery pipe; 4. Air outlet pipe; 5. One-way valve; 6. Control valve. Detailed Implementation

[0018] 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 some embodiments of the present invention, and not all embodiments. 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.

[0019] A bearing sealing system for an aero-engine under all operating conditions, such as Figure 1 As shown, it includes a first air intake pipe 1, a second air intake pipe 2, an air intake delivery pipe 3, and an air outlet pipe 4; the output ends of the first air intake pipe 1 and the second air intake pipe 2 are respectively connected to different intermediate stages of the compressor; a one-way valve 5 is connected to the first air intake pipe 1, and a control valve 6 is connected to the second air intake pipe 2; the positive direction of the one-way valve 5 is the intermediate stage of the compressor.

[0020] The input end of the air delivery pipe 3 is connected to the output end of the first air delivery pipe 1 and the second air delivery pipe 2, and the output end is connected to the air outlet pipe 4. The air outlet pipe 4 is connected to the sealing cavity of the middle cavity bearing.

[0021] The intermediate stage of the compressor draws out sealing bleed gas at different positions. After the gas merges at the output ends of the first bleed pipe 1 and the second bleed pipe 2, it flows into the sealing cavity of the intermediate bearing to seal the intermediate cavity. The one-way valve 5 can ensure that the bleed gas from the first bleed pipe 1 can only flow from the bleed position to the bearing sealing position. When the outlet pressure is high, it can prevent the gas from flowing backward.

[0022] The control valve 6 can close when the pressure of the corresponding intermediate stage is low and open when the pressure is high.

[0023] The check valve 5 and the control valve 6 work together to output sealing gas at different temperatures and pressures.

[0024] like Figure 1As shown, when the engine is in a low-pressure state, the valve on the second bleed pipe 2 remains open, drawing high-pressure, low-temperature gas from the intermediate stage of the compressor corresponding to the second bleed pipe 2. At this time, the outlet pressure of the one-way valve 5 on the first bleed pipe 1 is higher than the inlet pressure, and the valve is closed. The gas sealing the intermediate cavity in the second bleed pipe 2 comes from the compressor 2 position, achieving sealing and heat insulation of the intermediate cavity. When the engine is in a high-pressure state, the gas pressure and temperature from the intermediate stage of the compressor corresponding to the second bleed pipe 2 are too high, and the valve remains closed. At this time, the inlet pressure of the one-way valve 5 on the first bleed pipe 1 is higher than the outlet pressure, and the valve is open, drawing low-pressure, low-temperature gas from the intermediate stage of the compressor corresponding to the first bleed pipe 1. The gas sealing the intermediate cavity in the bleed pipe comes from the intermediate stage of the compressor in the first bleed pipe 1, achieving sealing and heat insulation of the intermediate cavity.

[0025] Preferably, the sealing cavity of the intermediate bearing is provided with a bearing sealing device, such as a toothed seal; a first bleed sealing device is provided between the first bleed pipe 1 and the intermediate stage of the compressor, and a second bleed sealing device is provided between the second bleed pipe 2 and the intermediate stage of the compressor. The first and second bleed sealing devices can be made of various sealing components.

[0026] Preferably, the second air intake pipe 2 is located behind the first air intake pipe 1, and the air intake pressure of the second air intake pipe 2 at the outlet of the first air intake pipe 1 is greater than the air intake pressure of the first air intake pipe 1 itself at the outlet; when the control valve 6 is opened, the one-way valve 5 is closed. The first air intake pipe 1 and the second air intake pipe 2 will not output air simultaneously to prevent changes in the temperature and pressure of the sealing gas.

[0027] Preferably, when the compressor intermediate stage bleed air enters the first bleed air pipe 1 and the second bleed air pipe 2 at the moment the engine starts and reaches idle speed, the pressure difference of the bleed air delivered to the sealing cavity of the intermediate bearing is greater than or equal to the sealing pressure difference, so as to ensure sealing stability.

[0028] Preferably, when the control valve 6 switches states, if the pressure or temperature of the second air duct 2 exceeds the sealing limit, the bleed air entering the second air duct 2 from any position in the intermediate stage of the compressor enters the sealing cavity of the intermediate bearing, and the pressure difference of the bleed air in the intermediate cavity meets the sealing requirements.

[0029] Preferably, the control valve 6 is a mechanical valve, which is equipped with a pressure threshold and a temperature threshold. When the temperature of the corresponding intermediate stage of the compressor is greater than the temperature threshold or the pressure of the corresponding intermediate stage of the compressor is greater than the pressure threshold, the control valve 6 opens to achieve stable control.

[0030] At the same time, while considering the air intake position, the first air intake tube 1 and the second air intake tube 2 of appropriate size should also be designed so that the sealing pressure of the middle cavity will not fluctuate too much when the valve is switched.

[0031] In summary, this application has the following advantages:

[0032] One-way valves and control switch valves are versatile, highly reliable, low-cost, and technologically mature.

[0033] Compared to the gas source switching scheme, this reduces the complexity of the control law and increases system reliability;

[0034] It is relatively easy to modify existing solutions and reduce the workload of redesign.

[0035] Compared to the bleed air source switching scheme, the switching valve in this scheme only needs to function when the bleed air pressure reaches the design limit, without requiring a three-way switching mechanism. This results in a simpler mechanical structure, simpler control logic, and more universal and mature technology. Compared to the bearing cavity exhaust control scheme, it solves the problem of insufficient sealing due to excessively low bleed air pressure.

[0036] Finally, it should be noted that the accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0037] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bearing sealing system for an aero-engine under all operating conditions, characterized in that: It includes a first air intake pipe (1), a second air intake pipe (2), an air intake delivery pipe (3), and an air outlet pipe (4); the output ends of the first air intake pipe (1) and the second air intake pipe (2) are respectively connected to different intermediate stages of the compressor; a one-way valve (5) is connected to the first air intake pipe (1), and a control valve (6) is connected to the second air intake pipe (2); the positive direction of the one-way valve (5) is towards the intermediate stage of the compressor; The input end of the air delivery pipe (3) is connected to the output end of the first air delivery pipe (1) and the second air delivery pipe (2), and the output end is connected to the air outlet pipe (4). The air outlet pipe (4) is connected to the sealing cavity of the middle cavity bearing.

2. The bearing sealing system for aero-engines under all operating conditions as described in claim 1, characterized in that: The sealing cavity of the intermediate bearing is provided with a bearing sealing device, the first air duct (1) is provided with a first air duct sealing device between it and the intermediate stage of the compressor, and the second air duct (2) is provided with a second air duct sealing device between it and the intermediate stage of the compressor.

3. The bearing sealing system for aero-engines under all operating conditions as described in claim 1, characterized in that: The second air intake tube (2) is located behind the first air intake tube (1). The air intake pressure of the second air intake tube (2) at the outlet of the first air intake tube (1) is greater than the air intake pressure of the first air intake tube (1) itself at the outlet. When the control valve (6) is opened, the one-way valve (5) is closed.

4. The bearing sealing system for aero-engines under all operating conditions as described in claim 1, characterized in that: When the engine is just started and reaches idle speed, the bleed air from the intermediate stage of the compressor enters the first bleed air pipe (1) and the second bleed air pipe (2), and the pressure difference of the bleed air delivered to the sealing chamber of the intermediate bearing is greater than or equal to the sealing pressure difference.

5. The bearing sealing system for aero-engines under all operating conditions as described in claim 1, characterized in that: When the control valve (6) switches states, if the pressure or temperature of the second air duct (2) exceeds the sealing limit, the bleed air entering the second air duct (2) from any position in the intermediate stage of the compressor enters the sealing cavity of the intermediate bearing, and the pressure difference of the bleed air in the intermediate cavity meets the sealing requirements.

6. The bearing sealing system for aero-engines under all operating conditions as described in claim 1, characterized in that: The control valve (6) is a mechanical valve, which is equipped with a pressure threshold and a temperature threshold. When the temperature of the corresponding intermediate stage of the compressor is greater than the temperature threshold or the pressure of the corresponding intermediate stage of the compressor is greater than the pressure threshold, the control valve (6) opens.

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