High-safety undercarriage folding and unfolding system for medium-sized transport plane

Abstract

The invention belongs to an aircraft undercarriage driving technology, and relates to a high-safety undercarriage folding and unfolding system for a medium-sized transport plane. Comprising two sets of hydraulic sources including a first hydraulic source and a second hydraulic source, the two sets of hydraulic sources are backups for each other, the first hydraulic source is used for controlling folding and unfolding of the undercarriage when the undercarriage is normally folded and unfolded, and the second hydraulic source is used for achieving folding and unfolding of the undercarriage when the undercarriage is emergently put down; the two undercarriage control units are used for controlling electromagnetic valves in the system, the normal folding and unfolding function of the undercarriage is achieved, when the undercarriage is put down emergently, a second hydraulic source supplies pressure to control the undercarriage to be put down emergently, and when the hydraulic system fails, gravity is used for driving backup to put down the undercarriage.

Description

Technical Field

[0001] The invention belongs to aircraft landing gear driving technology and relates to a high-safety landing gear retracting and extending system for a medium-sized transport aircraft. Background Art

[0002] The aircraft landing gear can be retracted and lowered on the ground and in the air for aircraft landing, taxiing and ground support. The existing landing gear retraction and extension control system uses a relay to control the solenoid valve, which has simple control logic, few backup operation methods and low reliability. Summary of the invention

[0003] Purpose of the invention: To provide a high-safety landing gear retraction and extension system for a medium-sized transport aircraft, which solves the problem of high-safety retraction and extension control of the landing gear.

[0004] Technical solution:

[0005] A high-safety landing gear retraction and extension system for a medium-sized transport aircraft comprises: a total of two sets of hydraulic sources, namely a No. 1 hydraulic source and a No. 2 hydraulic source, the two sets of hydraulic sources are backed up for each other, the No. 1 hydraulic source is used to control the retraction and extension of the landing gear during normal retraction and extension of the landing gear, and the No. 2 hydraulic source is used to realize the retraction and extension of the landing gear during emergency lowering of the landing gear; two sets of landing gear control units are used to control the solenoid valve in the system to realize the normal retraction and extension function of the landing gear, the No. 2 hydraulic source is used to supply pressure to control the emergency lowering of the landing gear during emergency lowering of the landing gear, and gravity drive is used to backup the lowering of the landing gear when the hydraulic system fails.

[0006] Furthermore, it includes: a normal landing gear retraction switch 1, a first landing gear control unit 2, a landing gear / door proximity sensor 3, a second landing gear control unit 4, an emergency landing gear lowering switch 7, a first solenoid valve 8, a second solenoid valve 9, a third solenoid valve 10, a fourth solenoid valve 11, an emergency lowering solenoid valve 12, an emergency door opening oil tank 13, a hand pump 14, an emergency door opening hydraulic valve 18, a first energy selection valve 19, a second energy selection valve 20, The third energy selection valve 21, the fourth energy selection valve 22, the first upper lock 23, the second upper lock 24, the first lower lock 25, the second lower lock 26, the first main landing gear retracting and extending cylinder 27, the second main landing gear retracting and extending cylinder 28, the first main landing gear door retracting and extending cylinder 29, the second main landing gear door retracting and extending cylinder 30, the front landing gear door retracting and extending cylinder 31, the third upper lock 32, the front retracting and extending cylinder 33, the third lower lock 34,

[0007] When the landing gear is normally retracted or extended, the No. 1 hydraulic source supplies pressure; the input end of the first landing gear control unit 2 is connected to the first output end of the normal landing gear retraction and extension switch 1;

[0008] An input end of the second landing gear control unit 4 is connected to a second output end of the normal landing gear retraction and extension switch 1;

[0009] Two channels of the landing gear / door proximity sensor 3 are respectively connected to the output end of the first landing gear control unit 2 and the output end of the second landing gear control unit 4;

[0010] The first control end of the first landing gear control unit 2 is connected to the first control end of the first solenoid valve 8; the first control end of the second landing gear control unit 4 is connected to the second control end of the first solenoid valve 8;

[0011] The second control end of the first landing gear control unit 2 is connected to the first control end of the second solenoid valve 9; the second control end of the second landing gear control unit 4 is connected to the second control end of the second solenoid valve 9;

[0012] The third control end of the first landing gear control unit 2 is connected to the first control end of the third solenoid valve 10; the third control end of the second landing gear control unit 4 is connected to the second control end of the third solenoid valve 10;

[0013] The fourth control end of the first landing gear control unit 2 is connected to the first control end of the fourth solenoid valve 11; the fourth control end of the second landing gear control unit 4 is connected to the second control end of the fourth solenoid valve 11;

[0014] The normal oil inlet of the first energy selection valve 19 is connected to the oil outlet of the first solenoid valve 8; the normal oil inlet of the second energy selection valve 20 is connected to the oil outlet of the second solenoid valve 9; the normal oil inlet of the third energy selection valve 21 is connected to the oil outlet of the third solenoid valve 10; the normal oil inlet of the fourth energy selection valve 22 is connected to the oil outlet of the fourth solenoid valve 11;

[0015] The normal oil return port of the first energy selection valve 19 is connected to the oil return port of the first solenoid valve 8; the normal oil return port of the second energy selection valve 20 is connected to the oil return port of the second solenoid valve 9; the normal oil return port of the third energy selection valve 21 is connected to the oil return port of the third solenoid valve 10; the normal oil return port of the fourth energy selection valve 22 is connected to the oil return port of the fourth solenoid valve 11;

[0016] The normal oil outlet of the first energy selection valve 19 is connected to the oil inlet of the first uplock 23 and the second uplock 24; the normal oil outlet of the first energy selection valve 19 is also connected to the landing gear lowering chambers of the first main landing gear retracting and extending cylinder 27 and the second main landing gear retracting and extending cylinder 28 respectively;

[0017] The landing gear retraction chambers of the first main landing gear retraction actuator 27 and the second main landing gear retraction actuator 28 are connected to the normal oil return port of the first energy selection valve 19;

[0018] The landing gear retraction chambers of the first main landing gear retraction actuator 27 and the second main landing gear retraction actuator 28 are connected to the oil inlets of the first down lock 25 and the second down lock 26 respectively;

[0019] The normal oil outlet of the second energy selection valve 20 is connected to the opening chamber of the first main landing gear door retracting and extending cylinder 29 and the opening chamber of the second main landing gear door retracting and extending cylinder 30; the closing chamber of the first main landing gear door retracting and extending cylinder 29 and the closing chamber of the second main landing gear door retracting and extending cylinder 30 are connected to the normal oil return port of the second energy selection valve 20;

[0020] The normal oil outlet of the third energy selection valve 21 is connected to the opening chamber of the front landing gear door retracting and extending actuator 31; the closing chamber of the front landing gear door retracting and extending actuator 31 is connected to the normal oil return port of the third energy selection valve 21;

[0021] The normal oil outlet of the fourth energy selection valve 22 is connected to the oil inlet of the third upper lock 32; the normal oil outlet of the fourth energy selection valve 22 is also connected to the landing gear lowering chamber of the front lifting and retracting cylinder 33; the landing gear retracting chamber of the front lifting and retracting cylinder 33 is connected to the normal oil return port of the fourth energy selection valve 22; the landing gear retracting chamber of the front lifting and retracting cylinder 33 is connected to the oil inlet of the third lower lock 34;

[0022] When the full hydraulic emergency landing gear is lowered, the No. 2 hydraulic source supplies pressure, and the output end of the emergency landing gear lowering switch 7 is connected to the input end of the emergency lowering solenoid valve 12;

[0023] The emergency oil return port of the first energy selection valve 19 is connected to the oil return port of the emergency lowering solenoid valve 12; the emergency oil return port of the second energy selection valve 20 is connected to the oil return port of the emergency lowering solenoid valve 12; the emergency oil return port of the third energy selection valve 21 is connected to the oil return port of the emergency lowering solenoid valve 12; the emergency oil return port of the fourth energy selection valve 22 is connected to the oil return port of the emergency lowering solenoid valve 12;

[0024] The emergency oil inlet of the first energy selection valve 19 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil inlet of the second energy selection valve 20 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil inlet of the third energy selection valve 21 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil inlet of the fourth energy selection valve 22 is connected to the oil outlet of the emergency lowering solenoid valve 12;

[0025] The emergency oil outlet of the first energy selection valve 19 is connected to the oil inlet of the first uplock 23 and the second uplock 24; the emergency oil outlet of the first energy selection valve 19 is also connected to the landing gear lowering chambers of the first main landing gear retracting and extending cylinder 27 and the second main landing gear retracting and extending cylinder 28 respectively;

[0026] The landing gear retraction chambers of the first main landing gear retraction actuator 27 and the second main landing gear retraction actuator 28 are connected to the emergency oil return port of the first energy selection valve 19;

[0027] The landing gear retraction chambers of the first main landing gear retraction actuator 27 and the second main landing gear retraction actuator 28 are connected to the oil inlets of the first down lock 25 and the second down lock 26 respectively;

[0028] The emergency oil outlet of the second energy selection valve 20 is connected to the opening chamber of the first main landing gear door retracting and extending cylinder 29 and the opening chamber of the second main landing gear door retracting and extending cylinder 30; the closing chamber of the first main landing gear door retracting and extending cylinder 29 and the closing chamber of the second main landing gear door retracting and extending cylinder 30 are connected to the emergency oil return port of the second energy selection valve 20;

[0029] The emergency oil outlet of the third energy selection valve 21 is connected to the opening chamber of the front landing gear door retracting and extending actuator 31; the closing chamber of the front landing gear door retracting and extending actuator 31 is connected to the emergency oil return port of the third energy selection valve 21;

[0030] The emergency oil outlet of the fourth energy selection valve 22 is connected to the oil inlet of the third upper lock 32; the emergency oil outlet of the fourth energy selection valve 22 is also connected to the landing gear lowering chamber of the front lifting and retracting cylinder 33; the landing gear retracting chamber of the front lifting and retracting cylinder 33 is connected to the emergency oil return port of the fourth energy selection valve 22; the landing gear retracting chamber of the front lifting and retracting cylinder 33 is connected to the oil inlet of the third lower lock 34;

[0031] When the landing gear is lowered by gravity emergency, the emergency door opening oil tank 13 is connected to the inlet of the hand pump 14; the outlet of the hand pump 14 is connected to the inlet of the emergency door opening hydraulic valve 18;

[0032] The first pressure oil outlet of the emergency door opening hydraulic valve 18 is communicated with the opening chamber of the first main landing gear door retracting and extending cylinder 29 and the opening chamber of the second main landing gear door retracting and extending cylinder 30; the second pressure oil outlet of the emergency door opening hydraulic valve 18 is communicated with the opening chamber of the front landing gear door retracting and extending cylinder 31;

[0033] The oil return port of the emergency hatch door opening hydraulic valve 18 is connected to the lubrication and heat dissipation oil return circuit of the hand pump 14 and the oil return port of the emergency hatch door opening oil tank 13;

[0034] The mechanical lock hooks of the first upper lock 23 and the second upper lock 24 are connected to the steel cable;

[0035] The mechanical lock hook of the third upper lock 32 is connected to the steel cable.

[0036] Furthermore, the landing gear / door proximity sensor 3 is a position proximity sensor.

[0037] Furthermore, it also includes: a first bypass valve 5, wherein the high-pressure oil inlet of the first bypass valve 5 is connected to the high-pressure oil circuit of hydraulic source No. 1; the return oil outlet of the first bypass valve 5 is connected to the return oil circuit of hydraulic source No. 1; the high-pressure oil outlet of the first bypass valve 5 is connected to the pressure oil inlet of the first solenoid valve 8 and the pressure oil inlet of the second solenoid valve 9; the control end of the first bypass valve 5 is connected to the high-pressure oil circuit of hydraulic source No. 2; the four return oil inlets of the first bypass valve 5 are respectively connected to the high-pressure oil outlet of the first solenoid valve 8, the return oil circuit outlet of the first solenoid valve 8, the high-pressure oil outlet of the second solenoid valve 9, and the return oil circuit outlet of the second solenoid valve 9.

[0038] Further, the second bypass valve 6, the high-pressure oil inlet of the second bypass valve 6 is connected to the high-pressure oil circuit of hydraulic source No. 1; the return oil outlet of the second bypass valve 6 is connected to the return oil circuit of hydraulic source No. 1; the high-pressure oil outlet of the second bypass valve 6 is connected to the pressure oil inlet of the third solenoid valve 10 and the pressure oil inlet of the fourth solenoid valve 11; the control end of the second bypass valve 6 is connected to the high-pressure oil circuit of hydraulic source No. 2; the four return oil inlets of the second bypass valve 6 are respectively connected to the high-pressure oil outlet of the third solenoid valve 10, the return oil circuit outlet of the third solenoid valve 10, the high-pressure oil outlet of the fourth solenoid valve 11, and the return oil circuit outlet of the fourth solenoid valve 11.

[0039] Furthermore, a pressure gauge 15 is provided on the oil circuit between the outlet of the hand pump 14 and the inlet of the emergency hatch door opening hydraulic valve 18 .

[0040] Furthermore, an oil filter 16 is provided on the oil circuit between the outlet of the hand pump 14 and the inlet of the emergency hatch door opening hydraulic valve 18 .

[0041] Furthermore, a one-way valve 17 is provided on the oil circuit between the outlet of the hand pump 14 and the inlet of the emergency hatch door opening hydraulic valve 18 .

[0042] Furthermore, the solenoid valve 8 is a three-position four-way solenoid valve.

[0043] Beneficial effects:

[0044] The high-safety medium-sized transport aircraft landing gear retraction and extension system of the present invention is mainly used to control the retraction and extension of the landing gear. The high-safety retraction and extension of the aircraft landing gear is achieved, and the functional requirements of the aircraft landing taxiing and ground support are met. The requirements for reliable retraction and extension of the landing gear of the medium-sized transport aircraft in the air and on the ground are met. The safe landing and parking of the aircraft are ensured. The gap in the high-safety control of the opening and closing of the landing gear of the domestic medium-sized transport aircraft on the ground and in the air is filled. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1This is a schematic diagram of the landing gear retraction and extension system for a high-safety medium-sized transport aircraft;

[0046] Among them, 1. Normal landing gear retraction switch 2. First landing gear control unit 3. Landing gear / door proximity sensor 4. Second landing gear control unit 5. First bypass valve 6. Second bypass valve 7. Emergency landing gear lowering switch 8. First solenoid valve 9. Second solenoid valve 10. Third solenoid valve 11 Fourth solenoid valve 12. Emergency lowering solenoid valve 13. Emergency door opening oil tank 14. Hand pump 15. Pressure gauge 16. Oil filter 17. Check valve 18. Emergency door opening hydraulic valve 19. First energy Selector valve 20. Second energy selector valve 21. Third energy selector valve 22. Fourth energy selector valve 23. First upper lock. 24. Second upper lock. 25. First lower lock. 26. Second lower lock. 27. First main landing gear retraction and extension actuator 28. Second main landing gear retraction and extension actuator 29. First main landing gear door retraction and extension actuator 30. Second main landing gear door retraction and extension actuator 31. Front landing gear door retraction and extension actuator 32. Third upper lock 33. Front landing gear retraction and extension actuator 34. Third lower lock. DETAILED DESCRIPTION

[0047] The invention discloses a high-safety landing gear retraction and extension system for a medium-sized transport aircraft, which is provided with two sets of hydraulic sources, namely, hydraulic source No. 1 and hydraulic source No. 2. The two sets of hydraulic sources serve as backup for each other. Hydraulic source No. 1 is used to control the retraction and extension of the landing gear during normal retraction and extension of the landing gear, and hydraulic source No. 2 is used to realize the retraction and extension of the landing gear during emergency lowering of the landing gear. Two sets of landing gear control units are provided to control the solenoid valves in the system to realize the normal retraction and extension function of the landing gear. When the landing gear is lowered in an emergency, hydraulic source No. 2 supplies pressure to control the emergency lowering of the landing gear. When the hydraulic system fails, gravity-driven backup is used to lower the landing gear.

[0048] Combine the following Figure 1 The present invention is described in further detail:

[0049] The landing gear retraction and extension control system adopts manual control, electrical control, and hydraulic actuation to realize the retraction and extension of the front and main landing gears and the landing gear doors, and has three modes: normal retraction and extension, backup lowering, and mechanical emergency lowering. The system is powered by two 28V power supplies from the normal bus and the emergency bus. The normal landing gear retraction and extension system and the emergency retraction and extension system are supplied by hydraulic system No. 1 and hydraulic system No. 2 respectively. The landing gear and the door of the normal landing gear retraction and extension system are controlled by different retraction and extension solenoid valves respectively, and the logical sequence is coordinated by the electrical control system. The electrical control is synchronized by two self-monitoring control units, and the proximity sensor is used to detect the position information of the landing gear, landing gear door, etc., and the wheel load information and position information of the landing gear are transmitted to other aircraft systems in the form of bus and hard line. The emergency lowering adopts open-loop control, and an independent electrical switch controls the on-off of the emergency release solenoid valve oil circuit to realize emergency lowering. The front and main landing gears are equipped with the functions of emergency unlocking by steel cable, free lowering by gravity, and pneumatic auxiliary locking.

[0050] The principle block diagram of the landing gear retraction and extension control system is attached. Figure 1 .

[0051] like Figure 1The high-safety landing gear retraction and extension system of a medium-sized transport aircraft includes: a normal landing gear retraction and extension switch 1, a first landing gear control unit 2, a landing gear / door proximity sensor 3, a second landing gear control unit 4, an emergency landing gear lowering switch 7, a first solenoid valve 8, a second solenoid valve 9, a third solenoid valve 10, a fourth solenoid valve 11, an emergency lowering solenoid valve 12, an emergency door opening tank 13, a hand pump 14, an emergency door opening hydraulic valve 18, a first energy selection valve 19, a second energy selection valve 20, a third energy selection valve 21, a fourth energy selection valve 22, a first upper lock 23, a second upper lock 24, a first lower lock 25, a second lower lock 26, a first main landing gear retraction and extension actuator 27, a second main landing gear retraction and extension actuator 28, The first main landing gear door retracting and extending actuator cylinder 29, the second main landing gear door retracting and extending actuator cylinder 30, the front landing gear door retracting and extending actuator cylinder 31, the third upper lock 32, the front retracting and extending actuator cylinder 33, and the third lower lock 34, wherein, when the landing gear is normally retracted and extended, the No. 1 hydraulic source supplies pressure; the input end of the first landing gear control unit 2 is connected to the first output end of the normal landing gear retracting and extending switch 1; the input end of the second landing gear control unit 4 is connected to the second output end of the normal landing gear retracting and extending switch 1; the two channels of the landing gear / door proximity sensor 3 are respectively connected to the output end of the first landing gear control unit 2 and the output end of the second landing gear control unit 4; the first control end of the first landing gear control unit 2 is connected to the first control end of the first solenoid valve 8 ; The first control end of the second landing gear control unit 4 is connected to the second control end of the first solenoid valve 8; the second control end of the first landing gear control unit 2 is connected to the first control end of the second solenoid valve 9; the second control end of the second landing gear control unit 4 is connected to the second control end of the second solenoid valve 9; the third control end of the first landing gear control unit 2 is connected to the first control end of the third solenoid valve 10; the third control end of the second landing gear control unit 4 is connected to the second control end of the third solenoid valve 10; the fourth control end of the first landing gear control unit 2 is connected to the first control end of the fourth solenoid valve 11; the fourth control end of the second landing gear control unit 4 is connected to the second control end of the fourth solenoid valve 11; the normal oil inlet of the first energy selection valve 19 The normal oil return port of the first energy selection valve 19 is connected to the oil return port of the first solenoid valve 8; the normal oil inlet of the second energy selection valve 20 is connected to the oil outlet of the second solenoid valve 9; the normal oil inlet of the third energy selection valve 21 is connected to the oil outlet of the third solenoid valve 10; the normal oil inlet of the fourth energy selection valve 22 is connected to the oil outlet of the fourth solenoid valve 11; the normal oil return port of the first energy selection valve 19 is connected to the oil return port of the first solenoid valve 8; the normal oil return port of the second energy selection valve 20 is connected to the oil return port of the second solenoid valve 9; the normal oil return port of the third energy selection valve 21 is connected to the oil return port of the third solenoid valve 10; the normal oil return port of the fourth energy selection valve 22 is connected to the oil return port of the fourth solenoid valve 11;The normal oil outlet of the first energy selection valve 19 is connected to the oil inlet of the first upper lock 23 and the second upper lock 24; the normal oil outlet of the first energy selection valve 19 is also connected to the landing gear lowering chamber of the first main landing gear retracting actuator cylinder 27 and the second main landing gear retracting actuator cylinder 28 respectively; the landing gear retracting chamber of the first main landing gear retracting actuator cylinder 27 and the second main landing gear retracting actuator cylinder 28 is connected to the normal oil return port of the first energy selection valve 19; the landing gear retracting chamber of the first main landing gear retracting actuator cylinder 27 and the second main landing gear retracting actuator cylinder 28 is connected to the oil inlet of the first lower lock 25 and the second lower lock 26 respectively; the normal oil outlet of the second energy selection valve 20 is connected to the first main landing gear door retracting actuator cylinder 2 9 is connected to the opening chamber of the second main landing gear door retracting actuator cylinder 30; the closing chamber of the first main landing gear door retracting actuator cylinder 29 and the closing chamber of the second main landing gear door retracting actuator cylinder 30 are connected to the normal oil return port of the second energy selection valve 20; the normal oil outlet of the third energy selection valve 21 is connected to the opening chamber of the front landing gear door retracting actuator cylinder 31; the closing chamber of the front landing gear door retracting actuator cylinder 31 is connected to the normal oil return port of the third energy selection valve 21; the normal oil outlet of the fourth energy selection valve 22 is connected to the oil inlet of the third upper lock 32; the normal oil outlet of the fourth energy selection valve 22 is also connected to the landing gear lowering chamber of the front retracting actuator cylinder 33; the landing and lifting chamber of the front retracting actuator cylinder 33 The landing gear stowage chamber is connected to the normal oil return port of the fourth energy selection valve 22; the landing gear stowage chamber of the front lifting and retracting actuator 33 is connected to the oil inlet of the third lower lock 34; wherein, when the full hydraulic emergency landing gear is lowered, the No. 2 hydraulic source supplies pressure, and the output end of the emergency landing gear lowering switch 7 is connected to the input end of the emergency lowering solenoid valve 12; the emergency oil return port of the first energy selection valve 19 is connected to the oil return port of the emergency lowering solenoid valve 12; the emergency oil return port of the second energy selection valve 20 is connected to the oil return port of the emergency lowering solenoid valve 12; the emergency oil return port of the third energy selection valve 21 is connected to the oil return port of the emergency lowering solenoid valve 12; the emergency oil return port of the fourth energy selection valve 22 is connected to the emergency lowering solenoid valve 1 2; the emergency oil inlet of the first energy selection valve 19 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil inlet of the second energy selection valve 20 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil inlet of the third energy selection valve 21 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil inlet of the fourth energy selection valve 22 is connected to the oil outlet of the emergency lowering solenoid valve 12; the emergency oil outlet of the first energy selection valve 19 is connected to the oil inlet of the first upper lock 23 and the second upper lock 24; the emergency oil outlet of the first energy selection valve 19 is also connected to the landing gear lowering chambers of the first main landing gear retraction and extension actuator 27 and the second main landing gear retraction and extension actuator 28 respectively;The landing gear retraction chambers of the first main landing gear retraction actuator 27 and the second main landing gear retraction actuator 28 are connected to the emergency oil return port of the first energy selection valve 19; the landing gear retraction chambers of the first main landing gear retraction actuator 27 and the second main landing gear retraction actuator 28 are connected to the oil inlets of the first down lock 25 and the second down lock 26 respectively; the emergency oil outlet of the second energy selection valve 20 is connected to the opening chamber of the first main landing gear door retraction actuator 29 and the opening chamber of the second main landing gear door retraction actuator 30; The closing chamber of the first main landing gear door retracting actuator 29 and the closing chamber of the second main landing gear door retracting actuator 30 are connected to the emergency oil return port of the second energy selection valve 20; the emergency oil outlet of the third energy selection valve 21 is connected to the opening chamber of the front landing gear door retracting actuator 31; the closing chamber of the front landing gear door retracting actuator 31 is connected to the emergency oil return port of the third energy selection valve 21; the emergency oil outlet of the fourth energy selection valve 22 is connected to the oil inlet of the third upper lock 32; the fourth energy selection valve The emergency oil outlet of 22 is also connected to the landing gear lowering chamber of the front lifting and retracting actuator 33; the landing gear retracting chamber of the front lifting and retracting actuator 33 is connected to the emergency oil return port of the fourth energy selection valve 22; the landing gear retracting chamber of the front lifting and retracting actuator 33 is connected to the oil inlet of the third lower lock 34; wherein, when the landing gear is lowered by gravity emergency, the emergency door opening oil tank 13 is connected to the inlet of the hand pump 14; the outlet of the hand pump 14 is connected to the inlet of the emergency door opening hydraulic valve 18; the first pressure oil of the emergency door opening hydraulic valve 18 The outlet is connected to the opening chamber of the first main landing gear door retracting cylinder 29 and the opening chamber of the second main landing gear door retracting cylinder 30; the second pressure oil outlet of the emergency door opening hydraulic valve 18 is connected to the opening chamber of the front landing gear door retracting cylinder 31; the oil return port of the emergency door opening hydraulic valve 18 is connected to the lubrication and heat dissipation oil return circuit of the hand pump 14 and the oil return port of the emergency door opening oil tank 13; the mechanical lock hooks of the first upper lock 23 and the second upper lock 24 are connected to the steel cable; the mechanical lock hook of the third upper lock 32 is connected to the steel cable.;

[0052] In a possible embodiment, the landing gear / door proximity sensor 3 is a position proximity sensor.

[0053] In a possible embodiment, it also includes: a first bypass valve 5, wherein the high-pressure oil inlet of the first bypass valve 5 is connected to the high-pressure oil circuit of hydraulic source No. 1; the return oil outlet of the first bypass valve 5 is connected to the return oil circuit of hydraulic source No. 1; the high-pressure oil outlet of the first bypass valve 5 is connected to the pressure oil inlet of the first solenoid valve 8 and the pressure oil inlet of the second solenoid valve 9; the control end of the first bypass valve 5 is connected to the high-pressure oil circuit of hydraulic source No. 2; the four return oil inlets of the first bypass valve 5 are respectively connected to the high-pressure oil outlet of the first solenoid valve 8, the return oil circuit outlet of the first solenoid valve 8, the high-pressure oil outlet of the second solenoid valve 9, and the return oil circuit outlet of the second solenoid valve 9.

[0054] In a possible embodiment, a second bypass valve 6, a high-pressure oil inlet of the second bypass valve 6 is connected to the high-pressure oil circuit of hydraulic source No. 1; the return oil outlet of the second bypass valve 6 is connected to the return oil circuit of hydraulic source No. 1; the high-pressure oil outlet of the second bypass valve 6 is connected to the pressure oil inlet of the third solenoid valve 10 and the pressure oil inlet of the fourth solenoid valve 11; the control end of the second bypass valve 6 is connected to the high-pressure oil circuit of hydraulic source No. 2; the four return oil inlets of the second bypass valve 6 are respectively connected to the high-pressure oil outlet of the third solenoid valve 10, the return oil circuit outlet of the third solenoid valve 10, the high-pressure oil outlet of the fourth solenoid valve 11, and the return oil circuit outlet of the fourth solenoid valve 11.

[0055] In a possible embodiment, a pressure gauge 15 is provided on the oil circuit between the outlet of the hand pump 14 and the inlet of the emergency hatch door opening hydraulic valve 18 .

[0056] In a possible embodiment, an oil filter 16 is provided on the oil circuit between the outlet of the hand pump 14 and the inlet of the emergency hatch door opening hydraulic valve 18 .

[0057] In a possible embodiment, a one-way valve 17 is provided on the oil circuit between the outlet of the hand pump 14 and the inlet of the emergency hatch door opening hydraulic valve 18 .

[0058] In a possible embodiment, the solenoid valve 8 is a three-position four-way solenoid valve.

[0059] Working principle:

[0060] 1Normal retraction system:

[0061] The normal retraction and extension of the landing gear is issued through the normal landing gear retraction and extension switch 1 located on the central instrument panel of the cockpit. The first landing gear control unit and the second landing gear control unit perform logic calculation according to the signals of the normal landing gear retraction and extension switch 1 and the landing gear / door proximity sensor 3 and issue a solenoid valve driving signal to drive the first solenoid valve 8, the second solenoid valve 9, the third solenoid valve 10, and the fourth solenoid valve 11. The electromagnetic coils of the first solenoid valve 8, the second solenoid valve 9, the third solenoid valve 10, and the fourth solenoid valve 11 work and control the oil circuit reversal to drive the first main landing gear door retraction and extension actuator 29, the second main landing gear door retraction and extension actuator 30, and the front landing gear door retraction and extension actuator 31; drive the first upper lock 23, the second upper lock 24 and the third upper lock 32; drive the first main landing gear retraction and extension actuator 27, the second main landing gear retraction and extension actuator 28, and the front retraction and extension actuator 33 to realize the retraction and extension of the landing gear and the opening and closing of the door.

[0062] After the landing gear and the door are retracted and put in place, the first landing gear control unit and the second landing gear control unit release the electromagnetic valve driving signals of the first electromagnetic valve 8, the second electromagnetic valve 9, the third electromagnetic valve 10, and the fourth electromagnetic valve 11 according to the signals detected from the corresponding landing gear / door proximity sensor 3, drive the landing gear signal light box to display the landing gear position, and transmit the landing gear position information, warning information, and maintenance information to the avionics system and the central maintenance system CMS through the electromechanical integrated management system EMS. The first landing gear control unit 2 and the second landing gear control unit 4 also send the landing gear position signal and the landing gear wheel load signal to other aircraft systems in the form of hard-wired discrete signals.

[0063] The control channel of the onboard landing gear control unit is logically processed by the first landing gear control unit 2 and the second landing gear control unit 4 according to the status of the normal landing gear retraction switch 1 and the landing gear / door proximity sensor 3, and the corresponding handle unlocking and landing gear retraction solenoid valve drive instructions are output at the same time. In order to ensure that the control outputs of the two control units are consistent, the landing gear position is judged by two sensors at the same position for comprehensive judgment. At the same time, in order to avoid non-command retraction and extension drive output due to failure of the control component, the monitoring component inside the control unit is designed with a solenoid valve drive line control function to actively disconnect the drive signal when the control component abnormally outputs the solenoid valve drive signal.

[0064] 2 Fully hydraulic emergency lowering system:

[0065] The backup lowering system is supplied with pressure by the No. 2 hydraulic system. The working principle of the system is shown in Figure 1 . The crew operates the emergency landing gear lowering switch 7 and controls the first bypass valve 5, the second bypass valve 6, the emergency lowering solenoid valve 12, the first energy selection valve 19, the second energy selection valve 20, the third energy selection valve 21, and the fourth energy selection valve 22 in a logical order to realize the sequential lowering function of the landing gear door and the landing gear. After the emergency release solenoid valve 12 works, the pressure oil first switches the first bypass valve 5 and the second bypass valve 6, and the oil circuits of the first solenoid valve 8, the second solenoid valve 9, the third solenoid valve 10, and the fourth solenoid valve 11 are returned to oil to prevent the first solenoid valve 8, the second solenoid valve 9, the third solenoid valve 10, and the fourth solenoid valve 11 from being stuck in the retracted landing gear position and the landing gear cannot be lowered. When the landing gear is in place and locked, the emergency landing gear lowering switch 7 returns to its initial position. The landing gear emergency release switch 7 is arranged on the right control panel of the cockpit.

[0066] 3 Gravity Emergency Lowering System:

[0067] The landing gear mechanical emergency lowering system crew completes the operation of opening the landing gear door by operating the hand pump 14. The hand pump 14 is manually operated to supply pressure to open the front and main hatch doors. A steel cable is set on the cockpit floor for emergency opening of the pull ring of the third upper lock 32 of the front landing gear; a steel cable is set on the left and right side walls of the cargo hold near the first upper lock 23 and the second upper lock 24 of the main landing gear for emergency opening of the first upper lock 23 and the second upper lock 24 of the left and right main landing gear. The driver manually pulls the pull ring of the third upper lock 32 to drive the front landing gear upper lock unlocking mechanism to work, and the front landing gear is lowered and locked by gravity and pneumatic force; the pull rings of the first upper lock 23 and the second upper lock 24 are pulled to drive the main landing gear upper lock unlocking mechanism to work, and the main landing gear is lowered and locked by gravity and pneumatic force.

[0068] The advantages of this configuration are: it is easy to use and operate, and the use of redundant configuration technology realizes the functions of highly safe retrieval and lowering of the landing gear on the ground and in the air, meeting the requirements of high reliability.

Claims

1. A high-safety landing gear retraction and extension system for a medium-sized transport aircraft, characterized in that: include: There are two sets of hydraulic sources, No. 1 hydraulic source and No. 2 hydraulic source, which backup each other. No. 1 hydraulic source is used to control the retraction and extension of the landing gear during normal retraction and extension, and No. 2 hydraulic source is used to achieve retraction and extension of the landing gear during emergency lowering of the landing gear. The two sets of landing gear control units are used to control the solenoid valves in the system to achieve normal retraction and extension of the landing gear. No. 2 hydraulic source is used to supply pressure to control the emergency lowering of the landing gear during emergency lowering of the landing gear. When the hydraulic system fails, gravity-driven backup is used to lower the landing gear.

2. The system according to claim 1, characterized in that include: Normal landing gear retraction switch (1), first landing gear control unit (2), landing gear / door proximity sensor (3), second landing gear control unit (4), emergency landing gear lowering switch (7), first solenoid valve (8), second solenoid valve (9), third solenoid valve (10), fourth solenoid valve (11), emergency lowering solenoid valve (12), emergency door opening oil tank (13), hand pump (14), emergency door opening hydraulic valve (18), first energy selection valve (19), second energy selection valve (20), third energy selection valve (21), a source selection valve (21), a fourth energy selection valve (22), a first upper lock (23), a second upper lock (24), a first lower lock (25), a second lower lock (26), a first main landing gear retracting and extending cylinder (27), a second main landing gear retracting and extending cylinder (28), a first main landing gear door retracting and extending cylinder (29), a second main landing gear door retracting and extending cylinder (30), a front landing gear door retracting and extending cylinder (31), a third upper lock (32), a front retracting and extending cylinder (33), and a third lower lock (34). When the landing gear is normally retracted or extended, the No. 1 hydraulic source supplies pressure; the input end of the first landing gear control unit (2) is connected to the first output end of the normal landing gear retraction and extension switch (1); An input end of the second landing gear control unit (4) is connected to a second output end of the normal landing gear retraction and extension switch (1); Two channels of the landing gear / door proximity sensor (3) are respectively connected to the output end of the first landing gear control unit (2) and the output end of the second landing gear control unit (4); The first control end of the first landing gear control unit (2) is connected to the first control end of the first solenoid valve (8); the first control end of the second landing gear control unit (4) is connected to the second control end of the first solenoid valve (8); The second control end of the first landing gear control unit (2) is connected to the first control end of the second solenoid valve (9); the second control end of the second landing gear control unit (4) is connected to the second control end of the second solenoid valve (9); The third control end of the first landing gear control unit (2) is connected to the first control end of the third solenoid valve (10); the third control end of the second landing gear control unit (4) is connected to the second control end of the third solenoid valve (10); The fourth control end of the first landing gear control unit (2) is connected to the first control end of the fourth solenoid valve (11); the fourth control end of the second landing gear control unit (4) is connected to the second control end of the fourth solenoid valve (11); The normal oil inlet of the first energy selection valve (19) is connected to the oil outlet of the first solenoid valve (8); the normal oil inlet of the second energy selection valve (20) is connected to the oil outlet of the second solenoid valve (9); the normal oil inlet of the third energy selection valve (21) is connected to the oil outlet of the third solenoid valve (10); and the normal oil inlet of the fourth energy selection valve (22) is connected to the oil outlet of the fourth solenoid valve (11); The normal oil return port of the first energy selection valve (19) is connected to the oil return port of the first solenoid valve (8); the normal oil return port of the second energy selection valve (20) is connected to the oil return port of the second solenoid valve (9); the normal oil return port of the third energy selection valve (21) is connected to the oil return port of the third solenoid valve (10); and the normal oil return port of the fourth energy selection valve (22) is connected to the oil return port of the fourth solenoid valve (11); The normal oil outlet of the first energy selection valve (19) is connected to the oil inlets of the first uplock (23) and the second uplock (24); the normal oil outlet of the first energy selection valve (19) is also connected to the landing gear lowering chambers of the first main landing gear retraction and extension actuator cylinder (27) and the second main landing gear retraction and extension actuator cylinder (28) respectively; The landing gear retraction chambers of the first main landing gear retraction actuator cylinder (27) and the second main landing gear retraction actuator cylinder (28) are connected to the normal oil return port of the first energy selection valve (19); The landing gear retraction chambers of the first main landing gear retraction actuator cylinder (27) and the second main landing gear retraction actuator cylinder (28) are respectively connected to the oil inlets of the first down lock (25) and the second down lock (26); The normal oil outlet of the second energy selection valve (20) is connected to the opening chamber of the first main landing gear door retracting and extending cylinder (29) and the opening chamber of the second main landing gear door retracting and extending cylinder (30); the closing chamber of the first main landing gear door retracting and extending cylinder (29) and the closing chamber of the second main landing gear door retracting and extending cylinder (30) are connected to the normal oil return port of the second energy selection valve (20); The normal oil outlet of the third energy selection valve (21) is communicated with the opening chamber of the front landing gear door retracting and extending actuator cylinder (31); the closing chamber of the front landing gear door retracting and extending actuator cylinder (31) is connected with the normal oil return port of the third energy selection valve (21); The normal oil outlet of the fourth energy selection valve (22) is connected to the oil inlet of the third upper lock (32); the normal oil outlet of the fourth energy selection valve (22) is also connected to the landing gear lowering chamber of the front lifting and retracting actuator cylinder (33); the landing gear retracting chamber of the front lifting and retracting actuator cylinder (33) is connected to the normal oil return port of the fourth energy selection valve (22); the landing gear retracting chamber of the front lifting and retracting actuator cylinder (33) is connected to the oil inlet of the third lower lock (34); When the landing gear is fully hydraulically lowered in an emergency, the No. 2 hydraulic source supplies pressure, and the output end of the emergency landing gear lowering switch (7) is connected to the input end of the emergency lowering solenoid valve (12); The emergency oil return port of the first energy selection valve (19) is connected to the oil return port of the emergency lowering solenoid valve (12); the emergency oil return port of the second energy selection valve (20) is connected to the oil return port of the emergency lowering solenoid valve (12); the emergency oil return port of the third energy selection valve (21) is connected to the oil return port of the emergency lowering solenoid valve (12); and the emergency oil return port of the fourth energy selection valve (22) is connected to the oil return port of the emergency lowering solenoid valve (12); The emergency oil inlet of the first energy selection valve (19) is connected to the oil outlet of the emergency lowering solenoid valve (12); the emergency oil inlet of the second energy selection valve (20) is connected to the oil outlet of the emergency lowering solenoid valve (12); the emergency oil inlet of the third energy selection valve (21) is connected to the oil outlet of the emergency lowering solenoid valve (12); and the emergency oil inlet of the fourth energy selection valve (22) is connected to the oil outlet of the emergency lowering solenoid valve (12); The emergency oil outlet of the first energy selection valve (19) is connected to the oil inlets of the first uplock (23) and the second uplock (24); the emergency oil outlet of the first energy selection valve (19) is also connected to the landing gear lowering chambers of the first main landing gear retraction and extension actuator cylinder (27) and the second main landing gear retraction and extension actuator cylinder (28) respectively; The landing gear retraction chambers of the first main landing gear retraction actuator cylinder (27) and the second main landing gear retraction actuator cylinder (28) are connected to the emergency oil return port of the first energy selection valve (19); The landing gear retraction chambers of the first main landing gear retraction actuator cylinder (27) and the second main landing gear retraction actuator cylinder (28) are respectively connected to the oil inlets of the first down lock (25) and the second down lock (26); The emergency oil outlet of the second energy selection valve (20) is connected to the opening chamber of the first main landing gear door retracting and extending cylinder (29) and the opening chamber of the second main landing gear door retracting and extending cylinder (30); the closing chamber of the first main landing gear door retracting and extending cylinder (29) and the closing chamber of the second main landing gear door retracting and extending cylinder (30) are connected to the emergency oil return port of the second energy selection valve (20); The emergency oil outlet of the third energy selection valve (21) is communicated with the opening chamber of the front landing gear door retracting and extending actuator cylinder (31); the closing chamber of the front landing gear door retracting and extending actuator cylinder (31) is connected with the emergency oil return port of the third energy selection valve (21); The emergency oil outlet of the fourth energy selection valve (22) is connected to the oil inlet of the third upper lock (32); the emergency oil outlet of the fourth energy selection valve (22) is also connected to the landing gear lowering chamber of the front lifting and retracting actuator cylinder (33); the landing gear retracting chamber of the front lifting and retracting actuator cylinder (33) is connected to the emergency oil return port of the fourth energy selection valve (22); the landing gear retracting chamber of the front lifting and retracting actuator cylinder (33) is connected to the oil inlet of the third lower lock (34); When the landing gear is lowered by gravity emergency, the emergency door opening oil tank (13) is connected to the inlet of the hand pump (14); the outlet of the hand pump (14) is connected to the inlet of the emergency door opening hydraulic valve (18); The first pressure oil outlet of the emergency door opening hydraulic valve (18) is communicated with the opening chamber of the first main landing gear door retracting and extending actuator cylinder (29) and the opening chamber of the second main landing gear door retracting and extending actuator cylinder (30); the second pressure oil outlet of the emergency door opening hydraulic valve (18) is communicated with the opening chamber of the front landing gear door retracting and extending actuator cylinder (31); The oil return port of the emergency hatch door opening hydraulic valve (18) is connected to the lubrication and heat dissipation oil return circuit of the hand pump (14) and the oil return port of the emergency hatch door opening oil tank (13); The mechanical lock hooks of the first upper lock (23) and the second upper lock (24) are connected to the steel cable; The mechanical lock hook of the third upper lock (32) is connected to the steel cable.

3. The system according to claim 2, characterized in that The landing gear / door proximity sensor (3) is a position proximity sensor.

4. The system according to claim 2, characterized in that Also includes: A first bypass valve (5), wherein the high-pressure oil inlet of the first bypass valve (5) is connected to the high-pressure oil circuit of the No. 1 hydraulic source; the return oil outlet of the first bypass valve (5) is connected to the return oil circuit of the No. 1 hydraulic source; the high-pressure oil outlet of the first bypass valve (5) is connected to the pressure oil inlet of the first solenoid valve (8) and the pressure oil inlet of the second solenoid valve (9); the control end of the first bypass valve (5) is connected to the high-pressure oil circuit of the No. 2 hydraulic source; and the four return oil inlets of the first bypass valve (5) are respectively connected to the high-pressure oil outlet of the first solenoid valve (8), the return oil circuit outlet of the first solenoid valve (8), the high-pressure oil outlet of the second solenoid valve (9), and the return oil circuit outlet of the second solenoid valve (9).

5. The system according to claim 2, characterized in that A second bypass valve (6), wherein the high-pressure oil inlet of the second bypass valve (6) is connected to the high-pressure oil circuit of the No. 1 hydraulic source; the return oil outlet of the second bypass valve (6) is connected to the return oil circuit of the No. 1 hydraulic source; the high-pressure oil outlet of the second bypass valve (6) is connected to the pressure oil inlet of the third solenoid valve (10) and the pressure oil inlet of the fourth solenoid valve (11); the control end of the second bypass valve (6) is connected to the high-pressure oil circuit of the No. 2 hydraulic source; and the four return oil inlets of the second bypass valve (6) are respectively connected to the high-pressure oil outlet of the third solenoid valve (10), the return oil circuit outlet of the third solenoid valve (10), the high-pressure oil outlet of the fourth solenoid valve (11), and the return oil circuit outlet of the fourth solenoid valve (11).

6. The system according to claim 2, characterized in that A pressure gauge (15) is provided on the oil circuit between the outlet of the hand pump (14) and the inlet of the emergency hatch door opening hydraulic valve (18).

7. The system according to claim 2, characterized in that An oil filter (16) is provided on the oil circuit between the outlet of the hand pump (14) and the inlet of the emergency hatch opening hydraulic valve (18).

8. The system according to claim 2, characterized in that A one-way valve (17) is provided on the oil circuit between the outlet of the hand pump (14) and the inlet of the emergency hatch opening hydraulic valve (18).

9. The system according to claim 2, characterized in that The solenoid valve (8) is a three-position four-way solenoid valve.

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