Aero turboprop engine lubricating oil system and aero turboprop engine

Abstract

The application discloses an aero turboprop engine lubricating oil system, which comprises a lubricating oil pressurizing device, an oil-gas separating device, a lubricating oil returning device, a lubricating oil filtering device, a lubricating oil monitoring device and connecting pipes connecting the devices; the lubricating oil pressurizing device comprises a main lubricating oil pump, an auxiliary lubricating oil pump and a torque measuring pump; the oil-gas separating device comprises an air inlet tank, an air separator and an oil mist separator; the lubricating oil returning device comprises a lubricating oil tank, a lubricating oil radiator, a middle and rear bearing oil pump, a transmission box oil pump and a direct current electric lubricating oil pump; the lubricating oil filtering device comprises a lubricating oil filter and a middle and rear bearing oil returning filter; and the lubricating oil monitoring device comprises a temperature metal chip signaler and a magnetic chip detection signaler. The application provides suitable lubricating oil pressure and oil quantity, improves the lubrication and heat dissipation of the friction surface of the internal parts of the engine and improves the use reliability of the engine.

Description

Technical Field

[0001] This invention belongs to the technical field of lubrication systems for aircraft turboprop engines, and in particular, relates to a lubrication system for an aircraft turboprop engine. This invention also relates to an aircraft turboprop engine. Background Technology

[0002] The lubricating oil system of an aircraft engine is a core auxiliary system that ensures the reliable operation of the engine. Its core function is to provide lubrication, cooling, cleaning and sealing protection for the moving parts of the engine. It mainly consists of an oil pump, a torque pump, an oil-gas separator and a monitoring device.

[0003] The lubrication system of an aircraft turboprop engine supplies oil to the friction surfaces of internal engine components for lubrication and cooling. It forms an oil film on the surfaces of moving parts such as bearings and gears to reduce friction and wear, preventing damage caused by dry friction. It also supplies oil to accessories such as the propeller governor, fuel regulator, and torque measuring mechanism, serving as the working medium for these accessories. The oil absorbs the heat generated by these components and transfers it away through the radiator, controlling the component temperature within a safe range. Simultaneously, the lubrication system ensures the pressure and quantity of the supplied oil. High-load friction surfaces of engine and accessory components are lubricated and cooled with pressurized oil, while low-load friction surfaces are lubricated and cooled with splashed oil.

[0004] In the existing technology, the lubricating oil system of aircraft turboprop engines does not have devices such as lubricating oil pressurization, oil-gas separation, and lubricating oil return. As a result, the lubricating oil cannot reach the engine's key components such as bearings and gears with sufficient pressure and flow, which leads to insufficient lubrication and cooling of these components, thereby aggravating wear and even causing overheating and damage to the components. At the same time, it will also cause unstable internal pressure of the engine, affecting the normal operation of the engine and reducing the engine's reliability and service life.

[0005] Patent application CN113530680A discloses an oil lubrication system and an aircraft turboshaft engine. The oil lubrication system uses a front bearing cavity formed by connecting the bearing cavity of the accessory drive and the bearing cavity of the compressor, and a rear bearing cavity formed by connecting the bearing cavity of the gas turbine and the bearing cavity of the power turbine. This achieves a common cavity design for multiple bearing cavities within the engine, effectively reducing the number of return oil pumps and oil lines, simplifying the oil lubrication system, and contributing to improved engine integration and weight reduction. Simultaneously, the front bearing cavity is positioned near the compressor's intake passage, utilizing the gas flow within the compressor's intake passage to dissipate heat and cool the oil in the front bearing cavity. This allows the oil to meet the cooling requirements of the engine's bearings, gears, and other friction pairs while using only one radiator. Furthermore, a safety valve and a shut-off valve are integrated into the oil pump assembly, further improving the engine's integration. However, the first chamber exhausts gas to the tail nozzle through a centrifugal ventilator, without an air isolation mechanism, which easily leads to accelerated lubricating oil oxidation and impurity mixing, which not only shortens the lubricating oil replacement cycle and increases the cost of use; it only relies on a single oil supply pump for oil supply, without an auxiliary lubricating oil pump, and cannot quickly fill the pipeline with oil when the engine starts, the boost function is limited, and the oil-gas separation path is limited in function. Summary of the Invention

[0006] This invention addresses the problem that existing aircraft turboprop engine lubrication systems lack devices for oil pressurization, oil-gas separation, and oil return. As a result, the lubricating oil cannot reach critical components such as bearings and gears with sufficient pressure and flow, leading to inadequate lubrication and cooling of these components. This exacerbates wear and may even cause overheating and damage to components. Furthermore, it can cause unstable internal engine pressure, affecting normal engine operation, reducing engine reliability and service life. This invention proposes an aircraft turboprop engine lubrication system and an aircraft turboprop engine.

[0007] An oil system for an aircraft turboprop engine is disclosed, comprising a closed-loop circulation circuit in which the oil sequentially passes through the engine, an oil radiator, and the engine. The oil system includes an oil pressurization device, an oil-gas separator, an oil return device, an oil filter, an oil monitoring device, and connecting conduits linking each device. The oil pressurization device includes a main oil pump, an auxiliary oil pump, and a torque pump. The oil-gas separator includes a vent tank, an air separator, and an oil mist separator. The oil return device includes an oil tank, an oil radiator, an oil pump for the intermediate and rear bearings, an oil pump for the transmission housing, and a DC electric oil pump. The oil filter includes an oil filter and an oil return filter for the intermediate and rear bearings. The oil monitoring device includes a temperature and metal shavings signal device and a magnetic shavings detection signal device.

[0008] The auxiliary oil pump has its inlet connected to the oil tank and its outlet connected to the inlet of the main oil pump, for replenishing the main oil pump with oil. The torque measuring pump has its inlet connected to the outlet of the main oil pump and its outlet connected to the engine's torque measuring mechanism, for supplying oil to the torque measuring mechanism. The oil-gas separator is connected to the oil return device, the oil tank, and the engine exhaust device, for separating air and oil mist from the oil. The oil return device is used to recover the oil from various engine components, which is then cooled by the oil radiator and returned to the main oil pump.

[0009] Furthermore, the main lubricating oil pump is a two-stage gear pump, including a booster stage and a return stage; the outlet of the booster stage of the main lubricating oil pump is connected to the lubricating oil filter, and is used to boost the lubricating oil and deliver it to the parts inside the engine that need lubrication and cooling, and to supply oil to the engine's fuel regulator, propeller governor and torque pump; the inlet of the return stage of the main lubricating oil pump is connected to the oil collection sump of the engine accessory transmission housing, its outlet is connected to the air separator, and the return stage of the main lubricating oil pump is connected to the hollow rectifier support plate of the accessory transmission housing.

[0010] Furthermore, the auxiliary lubricating oil pump is a single-stage gear oil pump, and the auxiliary lubricating oil pump is equipped with an auxiliary lubricating oil pressure regulating valve; the auxiliary lubricating oil pump maintains the inlet oil pressure of the main lubricating oil pump at 58.8 kPa to 78.4 kPa; the booster chamber of the auxiliary lubricating oil pump is equipped with a one-way valve, which opens when the oil pressure in the booster chamber reaches 19.6 kPa.

[0011] Furthermore, the torque measuring pump is a single-stage gear-type high-pressure oil pump. The oil inlet of the torque measuring pump is connected to the oil outlet of the main lubricating oil pump via the front lubricating oil filter and the oil passage in the reducer casing. The oil outlet of the torque measuring pump is connected to the torque measuring mechanism in the reducer casing.

[0012] Furthermore, the venting oil tank is installed on the lubricating oil tank; the air separator is centrifugal and installed on the lower left of the accessory gearbox, used to separate the air in the lubricating oil drawn back by the main lubricating oil pump return stage and the intermediate and rear bearing oil pump, the separated air carrying a small amount of oil mist flows into the lubricating oil tank, and the separated lubricating oil flows into the lubricating oil radiator; the oil mist separator is centrifugal and installed on the top of the accessory transmission gearbox, used to ventilate the turbine shaft cavity and separate the air in the oil mist of the turbine shaft cavity, the separated lubricating oil flows back to the accessory transmission gearbox along the spiral groove, and the separated air is discharged into the engine exhaust device.

[0013] Furthermore, the intermediate and rear bearing oil pump is a two-stage gear pump, installed on the lower left of the accessory transmission housing; its two inlets are connected to the oil collection pool of the engine turbine bearing (rear bearing) and the compressor rear bearing (intermediate bearing) respectively, and its outlet is connected to the air separator via a one-way valve, used to extract lubricating oil from the intermediate and rear bearings and transport it to the air separator, while simultaneously carrying away the frictional heat and metal debris of the intermediate and rear bearings; the transmission box oil pump is installed on the lower right of the transmission box, and its outlet is connected to the oil collection pool of the accessory transmission housing, used to pump the lubricating oil used in the transmission box back to the oil collection pool, and the lubricating oil flow rate of the transmission box oil pump is greater than 13.5 L / min when the outlet pressure is 29.4 kPa; the DC electric lubricating oil pump is installed below the main lubricating oil pump, its inlet pipe is connected to the accessory transmission housing, and its outlet is connected to the lubricating oil tank, used to pump the lubricating oil in the accessory transmission housing back to the lubricating oil tank before the engine restarts in the air.

[0014] Furthermore, the lubricating oil filter includes two mesh lubricating oil filters, which are installed on the right side of the accessory transmission housing; the middle and rear bearing return oil filter is installed directly below the front of the engine combustion chamber, and its oil inlet is connected to the middle bearing cavity and the rear bearing cavity of the engine, for filtering impurities in the lubricating oil flowing out from the middle bearing cavity and the rear bearing cavity.

[0015] Furthermore, two temperature metal shavings signal devices are provided, which are respectively installed on the oil return filter of the middle and rear bearings. The magnetic pole gap is 5±0.1mm and the alarm temperature is 180℃. When magnetic metal shavings accumulate between the two magnetic poles to connect the magnetic poles, or when the lubricating oil return temperature reaches 175~180℃, the fusible metal melts and fills the gap between the contact ring and the magnet, which will connect the circuit.

[0016] Furthermore, the lubricating oil filter is installed between the main lubricating oil pump outlet and the engine components requiring lubrication, as well as in the return oil path of the engine's middle and rear bearings, to filter impurities in the lubricating oil; the lubricating oil monitoring device is used to monitor the lubricating oil temperature and the wear condition of engine components.

[0017] An aircraft turboprop engine employs the aircraft turboprop engine lubrication system described in any one of claims 1 to 9.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. This invention utilizes a staged design for the lubricating oil pressurization device. The pressurization stage of the main lubricating oil pump (two-stage gear type) serves as the system's power source, ensuring a stable output of lubricating oil. This guarantees sufficient lubrication and cooling for internal engine components (such as rotor bearings and reducers) and accessories under various operating conditions, effectively reducing component wear and extending engine lifespan. The auxiliary lubricating oil pump replenishes lubricating oil and maintains the inlet oil pressure of the main lubricating oil pump (58.8 kPa~78.4 kPa), overcoming the shortcomings of existing technologies in high-altitude oil supply capability and ensuring continuous operation of the lubricating oil system in high-altitude environments. The torque measuring pump (single-stage high-pressure gear pump) provides a stable working medium for the torque measuring mechanism, ensuring accurate real-time torque monitoring and avoiding safety hazards caused by inaccurate torque measurement in existing technologies, thereby improving overall engine safety.

[0020] 2. The lubricating oil circulation in the turboprop lubricating oil system of the present invention is a closed-loop circulation, namely: engine—oil radiator—engine. The lubricating oil consumed during engine operation is replenished by an auxiliary oil pump drawing oil from the oil tank. The closed-loop circulation reduces the oxidation and deterioration of the lubricating oil due to contact with air, and at the same time prevents external impurities from entering the lubricating oil, significantly reducing the frequency of lubricating oil changes and the risk of wear on internal engine parts, thereby extending the service life of the engine lubricating oil and reducing costs.

[0021] 3. The oil pump for the middle and rear bearings of the present invention can promptly remove the lubricating oil from the middle and rear bearings, thereby avoiding leakage and sealing failure caused by the accumulation of lubricating oil, and removing the frictional heat of the bearings to prevent overheating and damage to the parts, while also adsorbing metal debris. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the lubricating oil system structure of the present invention;

[0023] In the above diagram, 1. Oil radiator; 2. Auxiliary oil pump; 3. Main oil pump booster stage; 4. Auxiliary oil pressure regulating valve; 5. Oil tank; 6. Accessory housing; 7. Front oil filter; 8. Rear oil filter; 9. Reducer; 10. Torque pump; 11. Transmission box; 12. Front bearing; 13. Middle bearing; 14. Rear bearing; 15. Governor; 16. Fuel regulator; 17. Main oil pump pressure regulating valve; 18. Accessory transmission housing oil sump; 19. Transmission. 20. Main lubricating oil pump return stage; 21. Rectifier support plates on both sides of the accessory transmission housing; 22. Air separator; 23. Middle and rear bearing oil pump; 24. Middle and rear bearing oil pump check valve; 25. Vent tank; 26. Auxiliary lubricating oil pump check valve; 27. Oil mist separator; 28. Engine exhaust nozzle; 29. ​​DC electric lubricating oil pump; 30. Magnetic debris detector; 31. Middle and rear bearing return oil filters; 32. Temperature and metal debris detector. Detailed Implementation

[0024] 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 may 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. In this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," 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 components or the interaction between two components. 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 expressly specified and limited, "on" or "below" a second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a 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 any suitable manner in one or more embodiments or examples.

[0025] Example 1

[0026] like Figure 1 As shown, an oil system for an aircraft turboprop engine is disclosed. The oil system forms a closed-loop circulation circuit, with the oil sequentially passing through the engine, oil radiator 1, and the engine itself. The oil system includes an oil pressurization device, an oil-gas separator, an oil return device, an oil filter, an oil monitoring device, and connecting conduits linking each device. The oil pressurization device includes a main oil pump, an auxiliary oil pump, and a torque pump 10. The oil-gas separator includes a vent tank 25, an air separator 22, and an oil mist separator 27. The oil return device includes an oil tank 5, an oil radiator 1, an oil pump for the intermediate and rear bearings, an oil pump for the transmission box, and a DC electric oil pump 29. The oil filter includes an oil filter and oil return filters for the intermediate and rear bearings 31. The oil monitoring device includes a temperature and metal shavings signal device and a magnetic shavings detection signal device 30.

[0027] The auxiliary oil pump has its inlet connected to the oil tank 5 and its outlet connected to the inlet of the main oil pump, for replenishing the main oil pump with oil. The torque measuring pump 10 has its inlet connected to the outlet of the main oil pump and its outlet connected to the engine's torque measuring mechanism, for supplying oil to the torque measuring mechanism. The oil-gas separator is connected to the oil return device, the oil tank 5, and the engine exhaust device, for separating air and oil mist in the oil. The oil return device is used to recover the oil from various engine components, which is then cooled by the oil radiator 1 and returned to the main oil pump.

[0028] In this embodiment, the main lubricating oil pump is a two-stage gear pump, including a booster stage and a return stage. The outlet of the booster stage 3 is connected to the lubricating oil filter, used to pressurize the lubricating oil and deliver it to the engine's internal parts requiring lubrication and cooling, and to supply oil to the engine's fuel regulator, propeller governor, and torque pump 10. The inlet of the return stage 20 is connected to the oil collection sump of the engine accessory drive housing, and its outlet is connected to the air separator 22. The return stage 20 is also connected to the rectifier support plates 21 on both sides of the accessory drive housing. The booster stage 3 is the power source for the lubricating oil system circulation, providing stable pressure to the entire lubricating oil system. This ensures that the lubricating oil is delivered at a constant flow rate and pressure through the pressure oil circuit in the accessory housing 6 to the engine's internal parts requiring lubrication and cooling, ensuring that these parts receive sufficient lubrication and cooling under different operating conditions. This effectively reduces wear on parts and improves engine reliability and service life. The main lubricating oil pump return stage 20 draws back the lubricating oil used by the reducer 9, accessory transmission device and transmission box from the oil collection pool of the accessory gearbox, and then cools the lubricating oil along the guide pipe and the rectifier support plates 21 on both sides of the accessory transmission gearbox, and heats the rectifier support plates to prevent icing. Then it flows into the air separator 22, realizing the circulation of lubricating oil and the anti-icing of the rectifier support plates, improving the utilization rate of lubricating oil and the working efficiency of the engine.

[0029] The auxiliary oil pump 2 is a single-stage gear pump, and it is equipped with an auxiliary oil pressure regulating valve 4. The auxiliary oil pump 2 maintains the inlet oil pressure of the main oil pump at 58.8 kPa to 78.4 kPa. A one-way valve is installed in the booster chamber of the auxiliary oil pump 2. This one-way valve opens when the oil pressure in the booster chamber reaches 19.6 kPa to prevent oil from flowing into the engine from the oil tank 5 when the engine is parked on the ground. Each turn of the adjusting screw on the auxiliary oil pressure regulating valve 4 changes the oil pressure in the booster chamber of the auxiliary oil pump 2 by approximately 14.7 kPa; the oil pressure increases when the adjusting screw is turned in and decreases when it is turned out.

[0030] The torque measuring pump 10 is a single-stage gear-type high-pressure oil pump, installed on the lower right side of the reducer 9 housing. The oil inlet of the torque measuring pump 10 is connected to the oil outlet of the main oil pump via the front lubricating oil filter 7 and the oil passage in the reducer 9 housing. The oil outlet of the torque measuring pump 10 is connected to the torque measuring mechanism in the reducer 9 housing, and is used to supply oil to the engine torque measuring mechanism. The lubricating oil flows from the main lubricating oil pump through the front lubricating oil filter 7 and the oil passage in the reducer 9 housing into the inlet of the torque measuring pump 10. After being pressurized by the torque measuring pump 10, it flows into the torque measuring mechanism in the reducer 9 housing through the oil outlet, ensuring that the torque measuring mechanism can accurately monitor the torque in real time, thereby improving the overall safety and reliability of the engine.

[0031] The vent tank 25 is installed above the lubricating oil tank 5. Air containing a small amount of oil mist in the lubricating oil tank 5 is discharged into the atmosphere through the vent tank 25, which helps maintain the cleanliness and efficient operation of the lubricating oil in the lubricating oil system. At the same time, some of the oil mist condenses into lubricating oil in the vent tank 25 and leaks back into the lubricating oil tank 5 to continue participating in the lubricating oil circulation, reducing the consumption of lubricating oil.

[0032] The air separator 22 is a centrifugal type, installed on the lower left side of the engine accessory housing. The inlet of the air separator 22 is connected to the return stage of the main lubricating oil pump and the outlet of the intermediate and rear bearing oil pump 23, respectively, to separate air from the lubricating oil. The separated air, carrying a small amount of oil mist, flows through a hose into the lubricating oil tank 5, and the separated lubricating oil flows through the outlet mounting seat into the lubricating oil radiator 1. Removing air from the lubricating oil reduces the gas content, ensures lubricating oil pressure, effectively lubricates internal engine parts, and reduces wear on the friction surfaces of the parts.

[0033] The oil mist separator 27 is a centrifugal type (centrifugal ventilator), installed on top of the engine accessory drive housing. It vents the engine turbine shaft cavity and separates air from the oil mist within the turbine shaft cavity. Under centrifugal force, the oil mist is thrown to the wall of the oil mist separator 27 housing and flows back to the accessory drive housing along the spiral groove. The separated air is discharged into the engine exhaust system through the impeller and shaft window, along the cover and the inner channel of the housing. The oil mist separator 27 separates the oil mist from the oil-air mixture in the lubricating oil system. The separated lubricating oil can be recycled and reused, reducing oil consumption, improving oil utilization, and lowering costs. Simultaneously, removing oil mist ensures smooth oil flow in the pipeline, maintains stable oil pressure, and guarantees that the lubricating oil can properly supply lubrication to the friction surfaces of internal engine parts.

[0034] The intermediate and rear bearing oil pump 23 is a two-stage gear oil pump installed on the lower left side of the accessory transmission housing. Its two inlets are connected to the oil collection pools of the engine turbine bearing (rear bearing) and the compressor rear bearing (intermediate bearing), respectively. The outlet is connected to the air separator 22 via the one-way valve 24 of the intermediate and rear bearing oil pump. It is used to extract lubricating oil from the intermediate and rear bearings and transport it to the air separator 22, while also carrying away the frictional heat and metal debris from the intermediate and rear bearings. The transmission box oil pump 19 is installed on the lower right side of the transmission box. Its outlet is connected to the oil collection pool 18 of the accessory transmission housing. It is used to extract lubricating oil from the transmission box into the oil collection pool. The lubricating oil flow rate of the transmission box oil pump 19 is greater than 13.5 L / min when the outlet pressure is 29.4 kPa. A DC electric lubricating oil pump 29 is installed below the main lubricating oil pump. Its inlet pipe is connected to the accessory drive housing, and its outlet is connected to the lubricating oil tank 5. It is used to draw lubricating oil from the accessory drive housing back to the lubricating oil tank 5 before the engine restarts in the air. The intermediate and rear bearing return oil filters 31 are installed directly below the front of the engine combustion chamber. Their inlets are connected to the intermediate bearing cavity and the rear bearing cavity of the engine. They are used to filter impurities in the lubricating oil flowing out of the intermediate bearing cavity and the rear bearing cavity.

[0035] In this embodiment, under ground operating conditions, closed-loop circulation reduces lubricating oil oxidation and deterioration (extending the lubricating oil replacement cycle by 50%), pressure boosting and stabilization ensure sufficient lubrication of all components, and real-time monitoring provides early warning of faults (fault detection rate reaches 100%), significantly improving the reliability and economy of the engine in ground operation.

[0036] Example 2

[0037] like Figure 1 As shown, in this embodiment, the lubrication system of the aircraft turboprop includes the following lubrication devices: a lubrication booster unit comprising a main lubrication pump, an auxiliary lubrication pump, and a torque pump; an oil-gas separation device comprising a venting tank 25, an air separator 22, and an oil mist separator 27; a lubrication return device comprising a lubrication tank 5, a lubrication radiator 1, a mid- and rear bearing oil pump 23, a transmission box oil pump 19, and a DC electric lubrication pump 29; a lubrication filtration device comprising a lubrication filter and mid- and rear bearing return oil filters 31; and a lubrication monitoring device comprising a temperature and metal shavings signal device, a magnetic shavings detection signal device 30, and connecting conduits.

[0038] In this embodiment, when the engine is operating normally, the working process of the lubricating oil system circulation circuit is as follows: used lubricating oil flows into the lubricating oil radiator 1 for heat dissipation and cooling. The lubricating oil coming out of the lubricating oil radiator 1 merges with the replenishing lubricating oil from the auxiliary lubricating oil pump 2 and flows into the main lubricating oil pump booster stage 3. The auxiliary lubricating oil pressure regulating valve 4 is used to regulate the outlet oil pressure of the auxiliary lubricating oil pump 2 to maintain the inlet oil pressure of the main lubricating oil pump at 58.8 kPa to 78.4 kPa, so as to improve the working capacity of the main lubricating oil pump at high altitude (or high-altitude environment). Turning the pressure regulating screw of the auxiliary lubricating oil pressure regulating valve 4 one turn will change the oil pressure in the booster chamber by about 14.7 kPa; turning it in increases the pressure, and turning it out decreases it. When the lubricating oil is consumed and cannot maintain this oil pressure, the auxiliary lubricating oil pump 2 draws lubricating oil from the lubricating oil tank 5 to replenish it and restore this pressure.

[0039] The lubricating oil is forced out by the main lubricating oil pump booster stage 3 and flows into two mesh oil filters (front lubricating oil filter 7 and rear lubricating oil filter 8) through the oil passage in the accessory casing 6. The filter screens have 12 to 13 meshes and a filtration fineness of 63 μm (8270 pores / cm). 2 After being filtered by the oil filter, the lubricating oil from the front lubricating oil filter 7 flows into the reducer 9 through the oil passage in the accessory gearbox 6, lubricating and cooling the internal parts of the reducer, and supplying oil to the torque pump 10. The lubricating oil from the rear lubricating oil filter 8 lubricates and cools the transmission parts in the accessory transmission device and transmission box 11, as well as the front bearing 12, middle bearing 13, and rear bearing 14 of the engine rotor; and supplies oil to the propeller governor 15 and fuel regulator 16.

[0040] When the engine is operating on the ground and the lubricating oil temperature is 70℃~80℃, the main lubricating oil pump pressure regulating valve 17, located at the outlet of the main lubricating oil pump booster stage, maintains the oil pressure at the lubricating oil filter outlet at 490kPa~539kPa. When the oil pressure is too high, the main lubricating oil pump pressure regulating valve 17 is opened, and some lubricating oil flows back to the main lubricating oil pump inlet chamber. Tightening the pressure regulating screw of the main lubricating oil pump pressure regulating valve 17 by one turn changes the lubricating oil outlet pressure by approximately 19.6kPa; tightening it increases the pressure, and tightening it out decreases it.

[0041] The lubricating oil used in the reducer 9 and accessory transmission device flows into the accessory transmission housing oil collection sump 18, and the lubricating oil used in the transmission box 11 is also pumped back into the accessory transmission housing oil collection sump 18 by the transmission box oil pump 19. The transmission box oil pump 19 pumps the lubricating oil used in the transmission box 11 back into the accessory transmission housing oil collection sump 18. When the outlet pressure is 29.4 kPa, the lubricating oil flow rate is greater than 13.5 L / min.

[0042] The lubricating oil in the accessory drive housing oil sump 18 is drawn out by the main lubricating oil pump return stage 20 and flows along the guide pipe into the rectifier support plates 21 on both sides of the accessory drive housing, cooling the lubricating oil and providing heating and anti-icing for the rectifier support plates, before flowing into the air separator 22. At the same time, the lubricating oil used by the engine's middle bearing 13 and rear bearing 14 is drawn out by the middle and rear bearing oil extraction pump 23 and flows into the air separator 22 through the middle and rear bearing oil extraction pump check valve 24.

[0043] Air separator 22 separates air from the used lubricating oil. The degassed lubricating oil flows along a hose into the lubricating oil radiator 1, and after cooling, flows back to the inlet of the main lubricating oil pump booster stage 3. The separated air, containing a small amount of oil mist, flows along a hose into the lubricating oil tank 5, and then is discharged into the atmosphere through the vent tank 25. Some of the oil mist condenses into lubricating oil in the vent tank 25 and leaks back into the lubricating oil tank 5.

[0044] When the aircraft is parked on the ground, in order to prevent the lubricating oil in the oil tank 5 from flowing into the engine, an auxiliary oil pump check valve 26 is installed in the pressurization chamber of the auxiliary oil pump 2. This prevents the lubricating oil in the oil tank 5 from flowing into the engine when the engine is parked on the ground. The auxiliary oil pump check valve 26 can only be opened when the oil pressure in the pressurization chamber reaches 19.6 kPa.

[0045] The oil mist formed by the bearings 13 and 14 in the lubricated engine passes through the oil mist separator 27 during its journey to the exhaust system. The oil mist separates the lubricating oil from the oil mist, and the lubricating oil flows into the accessory housing 6. The air is then discharged from the exhaust system into the engine tail nozzle 28 through the pipeline.

[0046] Before restarting the engine in the air, the DC electric oil pump 29 is turned on to pump the oil from the engine accessory transmission housing back to the oil tank 5.

[0047] To monitor the lubrication and wear conditions inside the engine, a magnetic debris detector 30 is installed at the oil sump in the lower part of the accessory transmission housing in the lubricating oil circuit. The magnetic pole gap is 3.50-0.5mm. When abnormal wear or damage occurs in engine parts, the magnetic debris carried by the lubricating oil flows through the magnetic debris detector and is attracted by the probe. When the attracted metal debris connects the housing and the probe, the circuit is connected, and the engine indicator and unit alarm system installed in the cockpit will issue an alarm signal to monitor the wear and lubricating oil contamination inside the engine.

[0048] Each of the middle and rear bearing return oil filters 31 is equipped with a temperature metal shavings signal 32, with a magnetic pole gap of 5±0.1mm and an alarm temperature of 175~180℃. When magnetic metal shavings collect between the two magnetic poles of the temperature metal shavings signal 32 and connect the two magnetic poles, the circuit is connected; or when the lubricating oil return temperature reaches 175~180℃, the fusible metal melts and flows downward, filling the gap between the contact ring and the magnet, the circuit is connected, and the engine indicator and unit alarm system installed in the cockpit will issue an alarm signal to monitor the lubrication and wear of the engine's middle and rear bearings.

[0049] Example 3

[0050] This embodiment focuses on the monitoring and maintenance functions of the lubricating oil system of aircraft turboprop engines, and describes in detail the working mechanism of the lubricating oil monitoring device and its role in ensuring engine reliability.

[0051] Two signal devices are installed on the return oil filters 31 of the middle and rear bearings, respectively, with a magnetic pole gap of 5±0.1mm and an alarm temperature of 180℃. When magnetic metal shavings accumulate and connect the magnetic poles, or when the lubricating oil return temperature reaches 180℃, the fusible metal melts and fills the gap, the circuit is connected, and the cockpit alarm system is triggered.

[0052] The magnetic debris detector 30 is installed at the oil sump 18 of the accessory transmission housing, with a magnetic pole gap of 3.5mm. When magnetic debris generated by the wear of internal engine parts is attracted by the probe and connects to the housing, the circuit is activated, and an alarm signal is issued.

[0053] The DC electric lubricating oil pump 29 automatically operates before restarting in mid-air, drawing lubricating oil from the accessory drive housing back to the lubricating oil tank 5 to ensure normal circulation. The oil mist separator 27 recovers lubricating oil from the oil mist in the turbine shaft cavity, reducing consumption; the air separator 22 ensures stable pressure after degassing the lubricating oil. In the lubricating oil filtration system, the lubricating oil filter and the intermediate and rear bearing return oil filters 31 continuously filter impurities, protecting the lubricated components.

[0054] The monitoring device is linked with the engine indicator and unit alarm system to provide real-time information on lubricating oil temperature, contamination level, and component wear, facilitating timely maintenance. The system's closed-loop design reduces lubricating oil oxidation and impurity ingress, extending lubricating oil life and lowering operating costs.

[0055] 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. A lubricating oil system for an aircraft turboprop engine, wherein the lubricating oil forms a closed-loop circulation circuit, and the lubricating oil sequentially passes through the engine, the lubricating oil radiator, and the engine, characterized in that, The lubricating oil system includes a lubricating oil booster, an oil-gas separator, a lubricating oil return device, a lubricating oil filter, a lubricating oil monitoring device, and connecting pipes connecting each device; the lubricating oil booster includes a main lubricating oil pump, an auxiliary lubricating oil pump, and a torque measuring pump. The oil-gas separation device includes a venting oil tank, an air separator, and an oil mist separator; the lubricating oil return device includes a lubricating oil tank, a lubricating oil radiator, a middle and rear bearing oil pump, a transmission box oil pump, and a DC electric lubricating oil pump; the lubricating oil filtration device includes a lubricating oil filter and a middle and rear bearing return oil filter; the lubricating oil monitoring device includes a temperature metal chip signal device and a magnetic chip detection signal device. The auxiliary oil pump has its inlet connected to the oil tank and its outlet connected to the inlet of the main oil pump, for replenishing the main oil pump with oil. The torque measuring pump has its inlet connected to the outlet of the main oil pump and its outlet connected to the engine's torque measuring mechanism, for supplying oil to the torque measuring mechanism. The oil-gas separator is connected to the oil return device, the oil tank, and the engine exhaust device, for separating air and oil mist in the oil. The oil return device is used to recover oil from various engine components, which is then cooled by the oil radiator and returned to the main oil pump. The auxiliary oil pump is a single-stage gear pump and is equipped with an auxiliary oil pressure regulating valve. The auxiliary oil pump maintains the inlet oil pressure of the main oil pump at 58.8 kPa to 78.4 kPa. The booster chamber of the auxiliary oil pump is equipped with a one-way valve, which opens when the oil pressure in the booster chamber reaches 19.6 kPa. The venting oil tank is installed on the lubricating oil tank; the air separator is centrifugal and installed on the lower left of the accessory gearbox, used to separate air from the lubricating oil drawn back by the main lubricating oil pump return stage and the intermediate and rear bearing oil pump. The separated air carries a small amount of oil mist and flows into the lubricating oil tank, while the separated lubricating oil flows into the lubricating oil radiator; the oil mist separator is centrifugal and installed on the top of the accessory transmission gearbox, used to ventilate the turbine shaft cavity and separate air from the oil mist in the turbine shaft cavity. The separated lubricating oil flows back to the accessory transmission gearbox along the spiral groove, while the separated air is discharged into the engine exhaust system; The intermediate and rear bearing oil pump is a two-stage gear pump, installed on the lower left of the accessory transmission housing; its two inlets are connected to the engine turbine bearing oil collection pool and the compressor rear bearing oil collection pool, respectively, and its outlet is connected to the air separator via a one-way valve; the transmission box oil pump is installed on the lower right of the transmission box, and its outlet is connected to the oil collection pool of the accessory transmission housing, used to draw lubricating oil from the transmission box into the oil collection pool, and the lubricating oil flow rate of the transmission box oil pump is greater than 13.5 L / min when the outlet pressure is 29.4 kPa; the DC electric lubricating oil pump is installed below the main lubricating oil pump, its inlet pipe is connected to the accessory transmission housing, and its outlet is connected to the lubricating oil tank.

2. The lubricating oil system for an aircraft turboprop engine according to claim 1, characterized in that, The main lubricating oil pump is a two-stage gear pump, including a booster stage and a return stage. The outlet of the booster stage of the main lubricating oil pump is connected to the lubricating oil filter, which is used to boost the lubricating oil and deliver it to the parts inside the engine that need lubrication and cooling, and to supply oil to the engine's fuel regulator, propeller governor and torque pump. The inlet of the return stage of the main lubricating oil pump is connected to the oil collection sump of the engine accessory transmission housing, and its outlet is connected to the air separator. The return stage of the main lubricating oil pump is also connected to the hollow rectifier support plate of the accessory transmission housing.

3. The lubricating oil system for an aircraft turboprop engine according to claim 1, characterized in that, The torque measuring pump is a single-stage gear-type high-pressure oil pump. The oil inlet of the torque measuring pump is connected to the oil outlet of the main lubricating oil pump via the front lubricating oil filter and the oil passage in the reducer casing. The oil outlet of the torque measuring pump is connected to the torque measuring mechanism in the reducer casing.

4. The lubricating oil system for an aircraft turboprop engine according to claim 1, characterized in that, The lubricating oil filter includes two mesh lubricating oil filters, which are installed on the right side of the accessory transmission housing; the middle and rear bearing return oil filter is installed directly below the front of the engine combustion chamber, and its oil inlet is connected to the middle bearing cavity and the rear bearing cavity of the engine, and is used to filter impurities in the lubricating oil flowing out from the middle bearing cavity and the rear bearing cavity.

5. The lubricating oil system for an aircraft turboprop engine according to claim 1, characterized in that, Two temperature metal shavings signal devices are provided, which are respectively installed on the oil return filter of the middle and rear bearings. The magnetic pole gap is 5±0.1mm and the alarm temperature is 180℃. When magnetic metal shavings accumulate between the two magnetic poles to connect the magnetic poles or when the lubricating oil return temperature reaches 175~180℃, the fusible metal melts and fills the gap between the contact ring and the magnet, which will connect the circuit.

6. The lubricating oil system for an aircraft turboprop engine according to claim 1, characterized in that, The lubricating oil filter is installed between the main lubricating oil pump outlet and the engine components that require lubrication, as well as in the return oil line of the engine's middle and rear bearings, to filter impurities in the lubricating oil; the lubricating oil monitoring device is used to monitor the lubricating oil temperature and the wear of engine components.

7. An aircraft turboprop engine, characterized in that, The aircraft turboprop engine lubrication system described in any one of claims 1 to 6 is adopted.

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