Undercarriage, aircraft and folding and unfolding method

Abstract

The invention provides an undercarriage, an aircraft and a folding and unfolding method. The landing gear comprises a shortening mechanism which is connected between the supporting column and the piston rod and is used for driving the piston rod to retract; the shortening mechanism comprises a second crank guide rod mechanism and a hydraulic actuating cylinder, one end of the hydraulic actuating cylinder is connected to the outer cylinder, the other end of the hydraulic actuating cylinder is connected with a first connecting rod, the two ends of the first connecting rod are hinged to first crank guide rod mechanisms used for converting linear motion of the hydraulic actuating cylinder into swing, and one ends of the first crank guide rod mechanisms are connected with the outer cylinder. The other end of the first crank guide rod mechanism is movably connected with one end of a second crank guide rod mechanism in a plane driving mode, the other end of the second crank guide rod mechanism is hinged to the piston rod, and the second crank guide rod mechanism is hinged to the outer cylinder. The second crank guide rod mechanism is used for converting swing of the first crank guide rod mechanism into retraction of the piston rod. The compression stroke can be designed according to actual requirements, a complex hydraulic system is not needed, and the defects in the prior art are overcome.

Description

Technical Field

[0001] This invention relates to the field of aircraft technology, and more particularly to a landing gear, an aircraft, and a method for its deployment and retraction. Background Technology

[0002] With the rapid development of modern aircraft, the demand for high-performance, lightweight, multi-payload, and multi-mission aircraft is increasing, placing higher demands on the storage space of retractable landing gear. In particular, small and medium-sized aircraft and UAVs, due to limitations in weight, space, and aerodynamic shape, require the landing gear bay to be as compact as possible to facilitate the installation of more payload equipment to meet multi-mission needs.

[0003] To accommodate retractable landing gear within a compact storage space (cabin), the length of the landing gear needs to be shortened. Existing technical solutions include the following: (i) The landing gear buffer is treated as a whole, and the entire landing gear buffer is lifted and lowered through mechanical linkages and a hydraulic system to shorten the length of the landing gear. Its structure is as follows: Figure 13 As shown. This technical solution requires the design of a complex mechanical linkage mechanism to lift the buffer built into the landing gear. Furthermore, the mechanical linkage mechanism needs to withstand the loads from the ground during takeoff, landing, and parking of the aircraft. This requires the use of high-strength steel for the parts, resulting in a heavy structure and high production, use, and maintenance costs. (ii) By injecting or draining oil from the damper using the aircraft's hydraulic system, the length of the landing gear damper is shortened. Its structure is as follows: Figure 14 As shown in the diagram, this design incorporates a reservoir on the landing gear. The reservoir isolates the hydraulic fluid inside the shock absorber from the aircraft's hydraulic system via internal pistons and seals, storing the fluid required for the landing gear to shorten. Upon the landing gear retraction command being issued, the aircraft's hydraulic system pressurizes, causing the fluid in the reservoir to be injected into the shock absorber's hydraulic chamber through external piping. This compresses the gas volume inside the shock absorber, shortening its length. Simultaneously, the pressure supply to the aircraft's hydraulic system is cut off and maintained. The process is reversed when the landing gear is extended. However, this design presents several problems: the limited volume of the reservoir restricts the length reduction of the shock absorber; the thermal expansion and contraction of hydraulic fluid means that the operating environment affects the shock absorber's shortening length; and the design requires a feedback system to control the hydraulic valves of the reservoir, increasing the complexity of the landing gear system and reducing its reliability.

[0004] Figure 13 , Figure 14 In the diagram, Ⅰ is the outer sleeve connected to the fuselage, Ⅱ is the shortening mechanism, Ⅲ is the landing gear buffer, Ⅳ is the piping, and Ⅴ is the liquid reservoir. Summary of the Invention

[0005] The purpose of this invention is to provide a landing gear, an aircraft, and a method for retracting and extending it, which allows for the design of the compression stroke according to actual needs, eliminates the need for a complex hydraulic system, and overcomes the shortcomings of the prior art.

[0006] The technical solution of the present invention is: a landing gear, including a strut, the strut including an outer cylinder and a piston rod extending and retracting within the outer cylinder, characterized in that it further includes a shortening mechanism connected between the strut and the piston rod for driving the piston rod to retract; the shortening mechanism includes a second crank guide rod mechanism, a hydraulic actuator cylinder with one end connected to the outer cylinder and the other end connected to a connecting rod, both ends of the connecting rod being hinged to a first crank guide rod mechanism for converting the linear motion of the hydraulic actuator cylinder into oscillation, one end of the first crank guide rod mechanism being connected to the outer cylinder, the other end of the first crank guide rod mechanism being dynamically connected to one end of the second crank guide rod mechanism in a planar driving manner, the other end of the second crank guide rod mechanism being hinged to the piston rod, and the second crank guide rod mechanism being hinged to the outer cylinder; the second crank guide rod mechanism is used to convert the oscillation of the first crank guide rod mechanism into the retraction of the piston rod.

[0007] Preferably, the two first crank guide rod mechanisms and the two second crank guide rod mechanisms are symmetrically arranged along the axis of the support; the hydraulic actuator is parallel to the piston rod.

[0008] Preferably, the first crank guide rod mechanism includes a rocker arm and a connecting rod. The two ends of the connecting rod are respectively hinged to the connecting rod. The end of the connecting rod away from the connecting rod is hinged to the rocker arm. One end of the rocker arm is hinged to the outer cylinder. The other end of the rocker arm forms a first planar sliding joint. The first planar sliding joint is dynamically connected to the second crank guide rod mechanism.

[0009] Preferably, one end of the first rocker arm is provided with a first plane, and one end of the second rocker arm is provided with a second plane. The first plane is provided with a gap δ between it and the moving connection end of the second crank guide rod mechanism on one side, and the second plane is provided with a gap δ between it and the moving connection end of the second crank guide rod mechanism on the other side.

[0010] Preferably, the second crank guide rod mechanism includes a third connecting rod, a fourth connecting rod, a lower torque arm, and an upper torque arm. The third connecting rod is hinged to the outer cylinder to form a twelfth hinge shaft. One end of the third connecting rod is provided with a pin for dynamic connection with the first crank guide rod mechanism. The pin forms an eleventh hinge shaft. The other end of the third connecting rod is hinged to one end of the fourth connecting rod to form a thirteenth hinge shaft. The other end of the fourth connecting rod is hinged to the piston rod to form a fourteenth hinge shaft. The upper torque arm is hinged to the outer cylinder to form the sixteenth hinge shaft. One end of the upper torque arm is provided with a pin for dynamic connection with the first crank guide rod mechanism. The pin forms the fifteenth hinge shaft. The other end of the upper torque arm is hinged to one end of the lower torque arm to form the seventeenth hinge shaft. The other end of the lower torque arm is hinged to the piston rod to form the eighteenth hinge shaft.

[0011] Preferably, the lever arm of the first crank guide rod mechanism used to drive the second crank guide rod mechanism is greater than the distance from the eleventh hinge axis to the twelfth hinge axis, and at the same time, the lever arm of the first crank guide rod mechanism used to drive the second crank guide rod mechanism is greater than the distance from the fifteenth hinge axis to the sixteenth hinge axis.

[0012] Preferably, the axes of the two hinge shafts on the hydraulic actuator cylinder are parallel to plane ZX, and the axes of all other hinge shafts are perpendicular to plane ZX.

[0013] The present invention also provides an aircraft, including a fuselage, a strut actuator hinged to the fuselage, and the aforementioned landing gear. The fuselage has a cabin, the landing gear struts are hinged to the fuselage, and the strut actuator is hinged to an outer cylinder to drive the landing gear to retract into the cabin or to be lowered from the cabin.

[0014] Preferably, the cabin is equipped with a master lock, the power output end of the master lock is equipped with a lock hook, the first crank guide rod mechanism is equipped with an eighth hinge shaft, and the master lock drives the lock hook to rotate to engage or disengage from the eighth hinge shaft.

[0015] The present invention also provides a method for launching and recovering the aircraft as described above, comprising the following steps: Landing gear retracted: Step 1: With the landing gear in the lowered position, the drive strut actuator extends, pushing the strut to rotate around the first hinge axis to perform the retraction movement; Step 2: The stroke of the hydraulic actuator cylinder is shortened, pulling back the first connecting rod, which drives the first crank guide rod mechanism to swing. The swinging first crank guide rod mechanism drives the second crank guide rod mechanism to rotate in two opposite directions in a planar drive manner. The second crank guide rod mechanism drives the piston rod to retract into the inner part of the outer cylinder. Step 3: When the landing gear is retracted into the cabin and the upper lock is released, the locking hook is engaged and latches onto the first crank guide rod mechanism; thus completing the retraction of the landing gear. Landing gear down: Step 1: Open the upper lock, start the strut actuator to retract, and pull the strut to rotate around the first hinge axis to perform the lowering motion; Step two: After the landing gear leaves the cabin, the hydraulic actuator extends until a gap δ is formed between the drive end of the first crank guide rod mechanism and the moving connection end of the second crank guide rod mechanism; this completes the extension of the piston rod and the lowering of the landing gear.

[0016] Compared with related technologies, the beneficial effects of the present invention are as follows: 1. The shortening mechanism formed by the first crank guide rod mechanism and the second crank guide rod mechanism in the plane designed in this invention has a lever arm amplification effect, and the landing gear strut can achieve a large extension stroke by the small extension and retraction of the hydraulic actuator cylinder. Second, this invention utilizes the existing upper / lower anti-torsion arm structure of the landing gear, and compresses the piston rod by driving the first crank guide rod mechanism and the second crank guide rod mechanism of the plane through the hydraulic actuator cylinder, so that the piston rod can achieve theoretical full compression, and the compression stroke can be designed according to actual needs, without the need for a complex hydraulic system, thus solving the defects of the prior art; Third, this invention utilizes the existing upper / lower anti-torsion arm structure of the landing gear, and uses a hydraulic actuator to drive a planar linkage shortening mechanism to compress the buffer piston rod, thereby shortening the buffer length. Compared to the existing solution one, this invention has a simpler structure; the planar linkage shortening mechanism does not bear the landing gear landing load, resulting in a lighter structure and smaller footprint; furthermore, the ground maintenance space is relatively open, making it more personnel-friendly for maintenance. Compared to the existing solution two, this invention provides a greater landing gear length shortening stroke, eliminates the need for complex hydraulic systems and their control systems, and has relatively lower requirements for hydraulic system parameters such as pressure and flow rate. IV. The shortening mechanism of the present invention adopts two sets of separate crank guide rod mechanisms. When the landing gear is in the lowered state, the two sets of separate guide rod mechanisms have a gap value δ and work independently of each other. This ensures that the compression of the piston rod when the strut lands has no effect on the shortening mechanism, resulting in better maintainability. It also avoids compression of the piston rod when it is fully extended due to the assembly and manufacturing tolerances of the strut and hydraulic actuator. Furthermore, it avoids the impact force generated by the rapid extension of the piston rod after the aircraft takes off from the ground being transmitted to the mechanism, which could lead to damage to structural parts. Fifth, the two first crank guide rod mechanisms and the two second crank guide rod mechanisms of the present invention are symmetrically arranged along the axis of the support column, which can avoid the asymmetrical lateral load generated when the force of the hydraulic actuator is transmitted to the piston rod, causing an increase in the lateral friction between the piston rod and the inner hole of the outer cylinder. In severe cases, this can cause scratches on the piston rod surface, leading to seal failure and leakage. In addition, the symmetrical arrangement also provides a backup for the structural function of the second crank guide rod mechanism, improving the reliability of the mechanism. VI. The shortening mechanism of the present invention is provided with a hinge shaft adapted to the upper lock. By means of the upper lock's locking hook and the built-in mechanical lock of the hydraulic actuator, when the support is in the retracted state, there is no need to set up a separate locking column and locking seat mechanism, which reduces the overall weight of the structure and simplifies the design. In addition, by setting up the upper lock to provide locking holding force, the load requirement of the built-in mechanical lock of the hydraulic actuator can be reduced in the flight state of the aircraft, reducing the impact of flight impact load on the built-in mechanical lock and extending its service life. VII. The shortening mechanism of this invention has no special process requirements for its parts, is easy to disassemble and assemble, and is convenient to maintain; it reduces the cost of use and maintenance, is highly practical, easy to promote and apply, and meets the needs of modern aviation and civil equipment. Attached Figure Description

[0017] Figure 1 A front view schematic diagram of the landing gear structure provided by the present invention; Figure 2 A side view of the landing gear structure provided by the present invention; Figure 3 An isometric schematic diagram of the landing gear provided by the present invention; Figure 4 This is a schematic diagram of the various kinematic pairs in the landing gear provided by the present invention; Figure 5 A schematic diagram illustrating the connection principle of the shortening mechanism; Figure 6 A schematic diagram of the landing gear's motion trajectory provided by the present invention; Figure 7 This is a schematic diagram showing the upper-level lock in the locked state. Figure 8 This is a partial structural diagram of the outer cylinder; Figure 9 This is a schematic diagram of the structure of the pendulum rod 1; Figure 10 This is a schematic diagram of the second pendulum rod; Figure 11 This is a structural schematic diagram of link three; Figure 12 This is a schematic diagram of the upper torsion arm. Figure 13 A schematic diagram of Scheme 1 for shortening the length of the existing landing gear strut; Figure 14 The schematic diagram of Scheme 2 for shortening the length of the existing landing gear strut.

[0018] In the attached diagram: 1. Outer cylinder; 101. Double-eared lug hole; 102. Lug hole; 103. Lug hole; 104. Double-eared lug hole; 105. Double-eared lug hole; 2. Hydraulic actuator cylinder; 3. Swing rod one; 311. Double-eared lug hole; 312. Double-eared lug hole; 313. Plane; 4. Connecting rod two; 5. Pin; 511. Smooth rod; 6. Connecting rod three; 611. Double-eared lug hole; 612. Double-eared lug hole; 613. 7. Bearing bore; 8. Connecting rod four; 9. Wheel tire; 10. Piston rod; 11. Lower torque arm; 12. Upper torque arm; 13. Swing rod two; 14. Double lug hole; 15. Double lug hole; 16. Plane; 17. Connecting rod one; 18. Strut actuator; 19. Landing gear strut; 10. Fuselage; 11. Upper lock; 12. Lock hook; 13. Wheel center track line; 14. Cabin door; 25. Locking bolt; O 15-16 First hinge axis; O 15-14 Second hinge axis; O 14-16 Third hinge axis; O 2-1 Fourth hinge axis; O 2-13 Fifth hinge axis; O 4-13 Sixth hinge axis; P 3-5 Planar translation joint; O 3-1 , Seventh hinge axis; O 3-4 Eighth hinge axis; O 12-1 Ninth hinge axis; O 12-4 10th hinge axis; P 12-5 Planar translation joint; O 5-6 Eleventh hinge shaft; O 6-1 12th hinge axis; O 6-7 Thirteenth hinge shaft; O 7-9 Fourteenth hinge axis; O 5-11 15th hinge axis; O 11-1 Sixteenth hinge axis; O 10-11 Seventeenth hinge shaft; O 10-9 Eighteenth hinge shaft. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0020] like Figure 1 , Figure 2 , Figure 3As shown, the landing gear provided in this embodiment includes a strut 15, the strut 15 including an outer cylinder 1 and a piston rod 9 that extends and retracts within the outer cylinder 1. The landing gear also includes a shortening mechanism connected between the strut 15 and the piston rod 9 for driving the piston rod 9 to retract. The shortening mechanism includes a second crank guide rod mechanism 200, a hydraulic actuator 2 connected at one end to the outer cylinder 1 and at the other end to a connecting rod 13, and a first crank guide rod mechanism 100 hinged at both ends of the connecting rod 13 to convert the linear motion of the hydraulic actuator 2 into oscillation. One end of the first crank guide rod mechanism 100 is connected to the outer cylinder 1, and the other end of the first crank guide rod mechanism 100 is dynamically connected to one end of the second crank guide rod mechanism 200 in a planar drive manner. The other end of the second crank guide rod mechanism 200 is hinged to the piston rod 9 and the second crank guide rod mechanism 200 is hinged to the outer cylinder 1. The second crank guide rod mechanism 200 is used to convert the oscillation of the first crank guide rod mechanism 100 into the retraction of the piston rod 9, thereby shortening the strut and reducing the space required for landing gear retraction and storage.

[0021] The two first crank guide rod mechanisms 100 and the two second crank guide rod mechanisms 200 are symmetrically arranged along the axis of the support column 15. The hydraulic actuator 2 is parallel to the piston rod 9. This structural arrangement facilitates the compression and extension of the piston rod 9, and also avoids asymmetrical lateral loads when the force of the hydraulic actuator 2 is transmitted to the piston rod 9, which would increase the lateral friction between the piston rod 9 and the inner hole of the outer cylinder 1. In severe cases, this could cause scratches on the surface of the piston rod 9 and lead to seal failure and leakage. In addition, the symmetrical arrangement also provides a backup for the structural function of the second crank guide rod mechanism 200, improving the reliability of the mechanism.

[0022] like Figure 8 As shown, the outer cylinder 1 has a first lug hole 101, a second lug hole 102, a third lug hole 103, a fourth lug hole 104, and a fifth lug hole 105. The first lug hole 101 is located on the axis of the outer cylinder 1. The second lug hole 102 and the third lug hole 103 are located at the same height and are symmetrical about both ends of the axis of the outer cylinder 1. The fourth lug hole 104 and the fifth lug hole 105 are located at the same height and are symmetrical about both ends of the axis of the outer cylinder 1.

[0023] like Figure 3 , Figure 4 , Figure 5 As shown, one end of the hydraulic actuating cylinder 2 is connected to the first lug hole 101 of the outer cylinder 1 via the fourth hinge shaft O. 2-1 The other end of the hydraulic actuator cylinder 2 is hinged to the connecting rod 13 via the fifth hinge axis O. 2-13Hinged. The first crank guide rod mechanism 100 includes a first rocker arm 3, a second connecting rod 4, and a second rocker arm 12. The second crank guide rod mechanism 200 includes a third connecting rod 6, a fourth connecting rod 7, a lower torque arm 10, and an upper torque arm 11. Figure 9 As shown, the rocker arm 3 is provided with a sixth lug hole 311, a seventh lug hole 312, and a first plane 313 in sequence. Figure 10 As shown, the swing arm 12 is provided with a tenth lug hole 121, an eleventh lug hole 122, and a second plane 123 in sequence. Figure 11 As shown, the connecting rod 6 has an eighth lug hole 611, a ninth lug hole 612, and a bearing hole 613 arranged sequentially. Figure 12 As shown, the upper torque arm 11 is provided with a twelfth ear hole 111, a thirteenth ear hole 112 and a fourteenth ear hole 113 in sequence.

[0024] like Figure 3 , Figure 4 , Figure 5 As shown, the end of link 13 near the heading is connected to one end of link 4 via a sixth hinge axis O. 4-13 The other end of the connecting rod 4 is hinged, and the eighth hinge axis O is connected to it. 3-4 It is hinged to the seventh lug hole 312 on the rocker arm 13. The end of the connecting rod 13 away from the heading is connected to one end of another connecting rod 24 via another sixth hinge axis O. 4-13 The other end of the connecting rod 4 is hinged, and the tenth hinge axis O is connected to it. 12-4 It is hinged to the eleventh lug hole 122 of the rocker arm 2 12.

[0025] The sixth lug hole 311 of the rocker arm 3 is connected to the seventh hinge shaft O. 3-1 It is hinged to the second lug hole 102 on the outer cylinder 1. The tenth lug hole 121 on the swing rod 12 is connected to the ninth hinge shaft O. 12-1 It is hinged to the third lug hole 103 on the outer cylinder 1.

[0026] A pin 5 is installed in the eighth lug hole 611 on the connecting rod 3 6. The pin 5 extends axially to the outside of the connecting rod 3 6 and forms a smooth rod 511. The smooth rod 511 contacts the first plane 313 to form a planar sliding pair P. 3-5 Another pin 5 is installed in the twelfth ear hole 111 on the upper torque arm 11. The pin 5 extends axially to the outer side of the upper torque arm 11 and forms a smooth rod 511. The smooth rod 511 contacts the second plane 123 to form a planar sliding pair P. 12-5 .

[0027] The ninth lug hole 612 on the connecting rod 36 is connected to the twelfth hinge shaft O. 6-1It is hinged to the fourth lug hole 104 on the outer cylinder 1. The bearing hole 613 on the connecting rod 6 is connected to the thirteenth hinge shaft O. 6-7 One end of the connecting rod 4 is hinged to the other end of the connecting rod 4 7, which is connected to the fourteenth hinge axis O. 7-9 It is hinged to piston rod 9. The eleventh lug hole 122 on the upper torque arm 11 passes through the sixteenth hinge shaft O. 6-1 It is hinged to the fifth lug hole 105 on the outer cylinder 1. The fourteenth lug hole 113 on the upper torque arm 11 is connected to the seventeenth hinge shaft O. 10-11 One end of the lower torque arm 10 is connected to the other end of the lower torque arm 10 via the eighteenth hinge shaft O. 10-9 It is hinged to piston rod 9.

[0028] like Figure 3 , Figure 4 As shown, the fourth hinge axis O 2-1 Fifth hinge axis O 2-13 The axis is parallel to plane ZX, and the axes of the other hinge axes are parallel to each other and perpendicular to plane ZX. The rotational motion of each connecting axis about its respective hinge axis, as well as the extension and retraction motion of the hydraulic actuator 2, the strut actuator 14, and the landing gear strut piston rod 9, all occur within plane XZ. In another embodiment, the extension and retraction motion of the hydraulic actuator 2 can also form a certain angle with plane XZ.

[0029] like Figure 1 , Figure 4 , Figure 6 As shown, the present invention also provides an aircraft, including a fuselage 16 and a strut actuating cylinder 14 hinged to the fuselage 16. A cabin is provided within the fuselage 16, the cabin has a hatch 19, and an upper lock 17 is provided inside the cabin. A wheel tire 8 is mounted at the end of the piston rod 9. A second hinge shaft O is connected to the outer cylinder 1. 15-14 A strut-driven actuating cylinder 14 is hinged to the outer cylinder 1, with one end of the strut-driven actuating cylinder 14 located away from the outer cylinder 1 via a third hinge shaft O. 14-16 Hinged to the body 16. The end of the outer cylinder 1 furthest from the piston rod 9 is connected to the first hinge shaft O. 15-16 It is hinged to the body 16.

[0030] The hydraulic system of the aircraft powers the extension and retraction of the strut actuator 14, causing the strut 15 to revolve around the first hinge axis O. 15-16 The swing motion causes the strut 15 to retract along the wheel centerline 18 into or out of the landing gear bay. During the retraction and extension of the landing gear, the hydraulic system pressurizes the hydraulic actuator 2, causing the swing motion of the first and second swing rods 12 to drive the piston rod 9 to extend or retract, thus achieving the function of retraction or extension when the landing gear strut retracts or leaves the landing gear bay during extension (e.g., ...). Figure 6 (As shown).

[0031] like Figure 1 As shown, in the landing gear lowered state, due to the manufacturing and assembly tolerances of the full extension lengths of the strut 15 and hydraulic actuator 2, a clearance value δ is left between the rocker arm 1 3, rocker arm 2 12 and the pin 5 to ensure coordinated operation of the two crank guide rod mechanisms. This prevents the piston rod 9 of the landing gear strut 15 from being compressed when fully extended due to manufacturing and assembly tolerances. Additionally, it also prevents the impact force generated by the rapid extension of the landing gear piston rod 9 after takeoff from being transmitted to the crank guide rod mechanism 2, thus avoiding damage to structural components.

[0032] like Figure 4 , Figure 5 As shown, the lever arms (i.e., hinge shafts O) of the driving lever 3 and lever 12 are... 3-1 To O 5-6 O 12-1 To O 5-11 The distance between the two links is greater than the lever arm of the driven link (i.e., the hinge axis O). 5-6 To O 6-1 The distance), the lever arm of the upper torque arm 11 (i.e., the hinge shaft O) 5-11 To O 11-1 The distance (of the hydraulic actuator) is such that the hydraulic driving force of the hydraulic actuator 2 can be reduced, thereby lowering the pressure requirements of the aircraft's hydraulic system. Furthermore, through the lever arm amplification effect, a smaller extension / retraction stroke of the hydraulic actuator can achieve a larger extension / retraction stroke of the landing gear strut.

[0033] like Figure 3 , Figure 7 As shown, the eighth hinge axis O 3-4 The selected type is relatively long, and its end is equipped with a locking bolt 20. The upper lock 17 drives the locking hook 171 to rotate to engage or disengage from the eighth hinge axis O. 3-4 The landing gear strut is kept in the retracted state by the locking hook 171 of the upper lock 17 and the built-in mechanical lock of the hydraulic actuator 2. In addition, by setting the locking holding force provided by the upper lock 17, the load requirement of the built-in mechanical lock of the hydraulic actuator 2 can be reduced during flight, while reducing the impact of flight impact loads on the built-in mechanical lock and improving its service life.

[0034] The present invention also provides a method for launching and recovering an aircraft, comprising the following steps: S1, with the landing gear in the lowered position, pressure from the aircraft's hydraulic system pushes the strut actuator 14 to its lowered position, unlocking the built-in lock. The strut actuator 14 extends, causing the landing gear strut 15 to rotate around the first hinge axis O. 15-16 Rotational upward movement.

[0035] S2, under the pressure supplied by the aircraft's hydraulic system, the stroke of the hydraulic actuator 2 is shortened, and connecting rod 13 and connecting rod 24 drive the rocker arm 3 to rotate around the seventh hinge axis O.3-1 The pendulum motion simultaneously drives the pendulum rod 12 to rotate around the ninth hinge axis O. 12-1 The swinging motion. The planar sliding joint P formed by the contact between the pendulum 3 and the pin 5. 3-5 Drive link three around the twelfth hinge axis O 6-1 Rotational motion, thirteenth hinge axis O 6-7 The connecting rod 47 rotates around the fourteenth hinge axis O. 7-9 Rotation. The rocker arm 12 contacts the pin 5, forming a planar sliding pair P. 12-5 Drive the upper torque arm 11 around the sixteenth hinge axis O 11-1 Rotational motion and the seventeenth hinge axis O 10-11 Drive the lower torque arm 10 around the eighteenth hinge axis O 10-9 The rotation eventually drives the piston rod 9 to compress the oil and gas inside the outer cylinder 1, thus shortening the length of the landing gear strut.

[0036] S3, before the landing gear strut approaches the landing gear door 19, the hydraulic actuator 2 needs to complete the shortening action under the pressure of the aircraft hydraulic system and shorten the piston rod stroke to the required value.

[0037] S4, after the landing gear strut is retracted into the landing gear bay, it reaches the upper lock position. Under the pressure of the aircraft hydraulic system, the locking hook 171 is driven to engage with the locking bolt 20 to achieve locking. At the same time, the upper lock of the strut actuator 14 is locked, so that the strut 15 remains locked in the upper position.

[0038] The landing gear lowering process is the reverse of the above process. The difference is that after the landing gear lowering command is issued, the door 19 opens, and the locking hook 171 of the upper lock 17 disengages from the locking bolt 20 under the pressure of the aircraft hydraulic system. Then the landing gear is slowly lowered. After the landing gear strut leaves the landing gear door 19, the pressure of the aircraft hydraulic system pushes the hydraulic actuator 2 to extend until the first swing arm 3, the second swing arm 12 and the pin 5 reach the required clearance value δ, and at the same time the piston rod reaches its full extension.

[0039] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A landing gear comprising a strut (15), the strut (15) including an outer cylinder (1) and a piston rod (9) extending and retracting within the outer cylinder (1), characterized in that, It also includes a shortening mechanism connected between the support column (15) and the piston rod (9) for driving the piston rod (9) to retract; the shortening mechanism includes a second crank guide rod mechanism (200), a hydraulic actuator (2) with one end connected to the outer cylinder (1) and the other end connected to the connecting rod (13), both ends of the connecting rod (13) are hinged to a first crank guide rod mechanism (100) for converting the linear motion of the hydraulic actuator (2) into oscillation, one end of the first crank guide rod mechanism (100) is connected to the outer cylinder (1), the other end of the first crank guide rod mechanism (100) is dynamically connected to one end of the second crank guide rod mechanism (200) in a planar driving manner, the other end of the second crank guide rod mechanism (200) is hinged to the piston rod (9), and the second crank guide rod mechanism (200) is hinged to the outer cylinder (1); the second crank guide rod mechanism (200) is used to convert the oscillation of the first crank guide rod mechanism (100) into the retraction of the piston rod (9).

2. The landing gear according to claim 1, characterized in that, The two first crank guide rod mechanisms (100) and the two second crank guide rod mechanisms (200) are symmetrically arranged along the axis of the support (15); the hydraulic actuator (2) is parallel to the piston rod (9).

3. The landing gear according to claim 1 or 2, characterized in that, The first crank guide rod mechanism (100) includes a rocker arm (3) and a connecting rod (4). Both ends of the connecting rod (13) are hinged to the connecting rod (4). The end of the connecting rod (4) away from the connecting rod (13) is hinged to the rocker arm (3). One end of the rocker arm (3) is hinged to the outer cylinder (1). The other end of the rocker arm (3) forms a first planar sliding pair (P). 3-5 ), the first planar prismatic joint (P 3-5 ) and the second crank guide rod mechanism (200) are dynamically linked.

4. The landing gear according to claim 3, characterized in that, One end of the first rocker arm (3) is provided with a first plane (313), and one end of the second rocker arm (12) is provided with a second plane (123). The first plane (313) is provided with a gap δ between the moving connection end of the second crank guide rod mechanism (200) on one side, and the second plane (123) is provided with a gap δ between the moving connection end of the second crank guide rod mechanism (200) on the other side.

5. The landing gear according to claim 1 or 2, characterized in that, The second crank guide rod mechanism (200) includes connecting rod three (6), connecting rod four (7), lower torque arm (10) and upper torque arm (11), wherein connecting rod three (6) is hinged to the outer cylinder (1) to form a twelfth hinge shaft (O). 6-1 One end of the connecting rod three (6) is provided with a pin (5) for dynamic connection with the first crank guide rod mechanism (100), and the pin (5) forms an eleventh hinge shaft (O). 5-6 The other end of the third link (6) is hinged to one end of the fourth link (7) to form the thirteenth hinge axis (O). 6-7 The other end of the connecting rod (7) is hinged to the piston rod (9) to form the fourteenth hinge axis (O). 7-9 ); The upper torsion arm (11) is hinged to the outer cylinder to form the sixteenth hinge axis (O). 11-1 The upper torque arm (11) has a pin (5) at one end for dynamic connection with the first crank guide rod mechanism (100), and the pin (5) forms the fifteenth hinge shaft (O). 5-11 The other end of the upper torsion arm (11) is hinged to one end of the lower torsion arm (10) to form the seventeenth hinge shaft (O). 10-11 The other end of the lower torque arm (10) is hinged to the piston rod (9) to form the eighteenth hinge shaft (O). 10-9 ).

6. The landing gear according to claim 5, characterized in that, The lever arm of the first crank guide rod mechanism (100) used to drive the second crank guide rod mechanism (200) is greater than that of the eleventh hinge shaft (O). 5-6 ) to the twelfth hinge axis (O 6-1 The distance between the first crank guide rod mechanism (100) and the second crank guide rod mechanism (200) is greater than that between the fifteenth hinge shaft (O). 5-11 ) to the sixteenth hinge axis (O 11-1 ( ) distance.

7. The landing gear according to claim 1 or 2, characterized in that, The axes of the two hinge shafts on the hydraulic actuator cylinder (2) are parallel to the plane ZX, and the axes of all other hinge shafts are perpendicular to the plane ZX.

8. An aircraft comprising a fuselage (16) and a strut actuator (14) hinged to the fuselage (16), wherein a cabin is provided within the fuselage (16), characterized in that, It also includes the landing gear as claimed in any one of claims 1-7, wherein the strut (15) of the landing gear is hinged to the fuselage (16), and the strut actuator (14) is hinged to the outer cylinder (1) to drive the landing gear to retract into or out of the cabin.

9. The aircraft according to claim 8, characterized in that, The cabin is equipped with a master lock (17), and the power output end of the master lock (17) is equipped with a lock hook (171). The first crank guide rod mechanism (100) is equipped with an eighth hinge shaft (O). 3-4 The upper lock (17) drives the lock hook (171) to rotate to engage or disengage from the eighth hinge axis (O). 3-4 ).

10. A method for launching and recovering an aircraft as described in claim 8 or 9, characterized in that, Includes the following steps: Landing gear retracted: Step 1: With the landing gear in the lowered position, the drive strut actuator (14) extends, pushing the strut (15) around the first hinge axis (O). 15-16 Rotation executes the retraction and upward movement; Step 2: The stroke of the hydraulic actuator (2) is shortened, the connecting rod (13) is pulled back, and the first crank guide rod mechanism (100) is driven to swing. The swinging first crank guide rod mechanism (100) drives the second crank guide rod mechanism (200) to rotate in two opposite directions in a planar drive manner. The second crank guide rod mechanism (200) drives the piston rod (9) to retract into the inner part of the outer cylinder (1). Step 3: When the landing gear is retracted into the cabin and the upper lock (17) is released, the locking hook (171) is activated and engages with the first crank guide rod mechanism (100); the retraction of the landing gear is completed. Landing gear down: Step 1: Open the upper lock (17), start the strut actuator (14) to retract, and pull the support column (15) around the first hinge axis (O). 15-16 Rotation executes the lowering motion; Step 2: After the landing gear leaves the cabin, start the hydraulic actuator (2) to extend until a gap δ is formed between the drive end of the first crank guide rod mechanism (100) and the dynamic connection end of the second crank guide rod mechanism (200); complete the extension of the piston rod (9) and complete the landing gear lowering.

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