Integrated undercarriage cabin door folding and unfolding mechanism

Abstract

The invention provides an integrated undercarriage cabin door folding and unfolding mechanism, and belongs to the technical field of aviation, the integrated undercarriage cabin door folding and unfolding mechanism comprises a cylinder barrel assembly, a first end of the cylinder barrel assembly is in sealed connection with a rear end cover, an emergency pipe nozzle and an extending pipe nozzle are arranged outside the rear end cover, and the connecting end of the rear end cover and the cylinder barrel assembly is arranged to be of a stepped barrel structure; the first end of the cylinder barrel assembly is located in the stepped barrel structure, a retraction pipe nozzle is arranged outside the second end of the cylinder barrel assembly, and a piston assembly is arranged in the second end. A mechanical locking assembly is arranged in the first end of the piston assembly, an emergency piston assembly is arranged in a middle shaft area of the piston assembly, the mechanical locking assembly is located between the piston assembly and the emergency piston assembly, and the emergency pipe nozzle is communicated with the first end of the emergency piston assembly. The second end of the piston assembly extends out of the cylinder barrel assembly and is internally provided with a buffering assembly, and the buffering assembly is located at the second end of the emergency piston assembly. According to the scheme, the integration degree, safety and reliability of the landing gear cabin door folding and unfolding mechanism are improved.

Description

Technical Field

[0001] This application relates to the field of aviation technology, and in particular to an integrated landing gear door retraction mechanism. Background Technology

[0002] The landing gear door actuator cylinder plays a crucial role in the operation of aircraft landing gear doors, primarily providing the driving force for opening and closing the doors. It typically consists of a cylinder body, piston rod, hydraulic nozzle, and connectors. Hydraulic pressure drives the piston mechanism, outputting linear displacement to achieve the door opening and closing action. Currently, most common landing gear door actuator cylinders only include a hydraulic drive structure and a buffer structure, resulting in relatively simple functionality. The mechanical locking mechanism required for the door necessitates an external mechanical locking device, leading to a bulky, heavy, and costly overall door opening and closing mechanism. Summary of the Invention

[0003] In view of this, this application provides an integrated landing gear door retraction mechanism, overcoming the shortcomings of the single-function design in the prior art. It integrates the linear displacement output, mechanical locking, emergency operation, and end-effector buffering functions required during door opening and closing into the actuator cylinder. This provides a multi-functional door opening and closing mechanism integrating displacement output, mechanical locking, and emergency operation. This simplifies the overall door opening and closing device, reduces its weight, and lowers manufacturing costs.

[0004] This application provides an integrated landing gear door retraction mechanism, including a cylinder assembly. A rear end cover is sealed to the first end of the cylinder assembly. An emergency nozzle and an extension nozzle are located outside the rear end cover. The connection between the rear end cover and the cylinder assembly is a stepped cylindrical structure. The first end of the cylinder assembly is located inside the stepped cylindrical structure. A retractable nozzle is located outside the second end of the cylinder assembly. A piston assembly is located inside the cylinder assembly. A mechanical locking assembly is located inside the first end of the piston assembly. An emergency piston assembly is located in the central axis region of the piston assembly. The mechanical locking assembly is located between the piston assembly and the emergency piston assembly. The emergency piston assembly is hollow, and the emergency nozzle communicates with the first end of the emergency piston assembly. The second end of the piston assembly extends out of the cylinder assembly, and a buffer assembly is located inside the second end of the piston assembly.

[0005] According to a specific implementation of an embodiment of this application, the stepped cylindrical structure of the rear end cover has an outer wall and an inner wall, the first end of the cylinder assembly and the first end of the piston assembly are located between the outer wall and the inner wall, and the mechanical locking assembly and the emergency piston assembly are located inside the inner wall.

[0006] According to a specific implementation of an embodiment of this application, the mechanical locking assembly includes an unlocking piston assembly, a locking block, a return spring, a locking spring, and a spring seat. The unlocking piston assembly is located between the inner wall and the emergency piston assembly. A return spring is provided at the end of the unlocking piston assembly near the emergency nozzle, and a locking spring is provided at the end of the unlocking piston assembly away from the emergency nozzle. The locking spring is fixed to the piston assembly by the spring seat. The locking block is disposed on the inner wall, and the position of the locking block corresponds to the position of the emergency piston assembly. The emergency piston assembly is provided with a first groove and a first protrusion, and a second groove is provided on the inner wall of the piston assembly. The locking block cooperates with the first groove to unlock the piston assembly, and the locking block cooperates with the second groove to lock the piston assembly.

[0007] According to a specific implementation of an embodiment of this application, the buffer assembly includes a buffer piston, a pull rod, and a buffer spring. A partition is provided inside the second end of the piston assembly. The pull rod is vertically connected to the partition. The buffer piston and the buffer spring are sleeved on the pull rod. The buffer piston is close to the second end of the piston assembly and slides on the pull rod. One end of the buffer spring abuts against the buffer piston, and the other end of the buffer spring abuts against the partition. A first buffer damping hole is provided on the side wall of the pull rod, and a second buffer damping hole is provided on the rear end face of the pull rod. The first buffer damping hole and the second buffer damping hole communicate with each other.

[0008] According to one specific implementation of this application, the rear end face of the pull rod is provided with a second protrusion, which limits the buffer piston.

[0009] According to a specific implementation of the present application, a position signal indication structure is further provided on the outside of the second end of the cylinder assembly. The position signal indication structure includes a push rod, a proximity sensor and a target. The push rod is located in an inclined structure outside the cylinder assembly. One end of the push rod extends into the inner wall of the cylinder assembly, and the other end of the push rod is equipped with a target. The proximity sensor is fixed on the outside of the cylinder assembly, and the sensing end of the proximity sensor faces the target.

[0010] According to one specific implementation of this application, a front end ear is threadedly connected to the port of the second end of the piston assembly, and the front end ear is fixed by a lock nut.

[0011] According to a specific implementation of an embodiment of this application, a guide sleeve assembly is provided between the port of the second end of the cylinder assembly and the second end of the piston assembly, and a first seal is provided on the inner wall of the guide sleeve assembly.

[0012] According to a specific implementation of an embodiment of this application, the first end of the piston assembly is provided with a second seal, and both ends of the emergency piston assembly are provided with a third seal.

[0013] According to a specific implementation of the present application, a fourth sealing element is provided between the cylinder assembly and the outer wall, a fifth sealing element is provided between the unlocking piston assembly and the inner wall, and a sixth sealing element is provided between the unlocking piston assembly and the emergency piston assembly.

[0014] Beneficial effects: The integrated landing gear door retraction mechanism in this embodiment integrates the functions required for the landing gear door, including opening and closing, locking, buffering, emergency operation, and positioning signal. The entire mechanism is treated with a protective coating to ensure environmental adaptability. Both ends are connected to the aircraft door via spherical bearings to ensure flexible opening and closing. A retraction slider mechanical lock is integrated inside the actuator cylinder, eliminating the need for a separate mechanical lock and simplifying the system structure. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the landing gear door actuator cylinder structure according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the landing gear door actuator cylinder according to an embodiment of the present invention; Figure 3 This is a diagram of the main drive structure according to an embodiment of the present invention; Figure 4 A structural diagram of a mechanical lock according to an embodiment of the present invention; Figure 5 This is a diagram of an emergency drive structure according to an embodiment of the present invention; Figure 6 This is a diagram of an end-buffer structure according to an embodiment of the present invention; Figure 7 This is a structural diagram of a position signal indicator according to an embodiment of the present invention; Figure 8 This is a partially enlarged view of a pull rod according to an embodiment of the present invention.

[0017] In the diagram: 1. Rear end cap, 2. Joint bearing, 3. Emergency nozzle, 4. Return spring, 5. Emergency piston assembly, 6. Unlocking piston assembly, 7. Lock block, 8. Piston assembly, 9. Locking spring, 10. Spring seat, 11. Cylinder assembly, 12. Retractable nozzle, 13. Guide sleeve assembly, 14. Buffer piston, 15. Pull rod, 16. Buffer spring, 17. Locking nut, 18. Front end lug, 19. Proximity sensor, 20. Extending nozzle, 21. Push rod, 22. Target, 23. Buffer damping hole. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0019] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0023] In one embodiment, an integrated landing gear door retraction mechanism is provided, as described below. Figures 1 to 8 Detailed explanation follows. The integrated landing gear door retraction mechanism includes a cylinder assembly 11. The first end of the cylinder assembly 11 is sealed to a rear end cover 1. An emergency nozzle 3 and an extension nozzle 20 are provided on the outside of the rear end cover 1. The connection end between the rear end cover 1 and the cylinder assembly 11 is configured as a stepped cylindrical structure. The first end of the cylinder assembly 11 is located inside the stepped cylindrical structure. A retractable nozzle 12 is provided on the outside of the second end of the cylinder assembly 11. A piston assembly 8 is provided inside the cylinder assembly 11. A mechanical locking assembly is provided inside the first end of the piston assembly 8. An emergency piston assembly 5 is provided in the central axis region of the piston assembly 8. The mechanical locking assembly is located between the piston assembly 8 and the emergency piston assembly 5. The emergency piston assembly 5 is a hollow structure. The emergency nozzle 3 communicates with the first end of the emergency piston assembly 5. The second end of the piston assembly 8 extends out of the cylinder assembly 11, and a buffer assembly is provided inside the second end of the piston assembly 8. The buffer assembly is located at the second end of the emergency piston assembly 5.

[0024] In this embodiment, the overall structure is designed as a linear reciprocating double-acting actuator with an extendable mechanical locking mechanism. This compact design integrates multiple functions, effectively reducing the number of external connections and components, lowering the probability of failure, and improving system reliability. During the linear reciprocating motion, the rational design of the emergency nozzle and the extendable and retractable nozzles fulfills the driving requirements under different operating conditions. The extendable mechanical locking function ensures that the piston assembly 8 can reliably lock at specific positions, preventing unexpected door movement due to unforeseen factors and ensuring flight safety. Simultaneously, this design makes the installation and maintenance of the entire mechanism on the aircraft more convenient, saving valuable space resources and significantly contributing to improving the overall performance and operational efficiency of the aircraft.

[0025] Specifically, the integrated landing gear door retraction mechanism includes a main drive structure, a positioning mechanical locking structure, an end-effector buffer structure, an emergency drive structure, and a positioning signal indication structure. Each structure is described in detail below.

[0026] In one embodiment, the stepped cylindrical structure of the rear cover 1 has an outer wall and an inner wall, the first end of the cylinder assembly 11 and the first end of the piston assembly 8 are located between the outer wall and the inner wall, and the mechanical locking assembly and the emergency piston assembly 5 are located inside the inner wall.

[0027] In one embodiment, refer to Figure 4The mechanical locking assembly includes an unlocking piston assembly 6, a locking block 7, a return spring 4, a locking spring 9, and a spring seat 10. The unlocking piston assembly 6 is located between the inner wall and the emergency piston assembly 5. The return spring 4 is provided at the end of the unlocking piston assembly 6 near the emergency nozzle 3, and the locking spring 9 is provided at the end of the unlocking piston assembly 6 away from the emergency nozzle 3. The locking spring 9 is fixed to the piston assembly 8 by the spring seat 10. The locking block 7 is provided on the inner wall, and the position of the locking block 7 corresponds to the position of the emergency piston assembly 5. The emergency piston assembly 5 is provided with a first groove and a first protrusion, and the inner wall of the piston assembly 8 is provided with a second groove. The locking block 7 cooperates with the first groove to unlock the piston assembly 8, and the locking block 7 cooperates with the second groove to lock the piston assembly 8.

[0028] In practice, the mechanical locking assembly is designed in series inside the actuating cylinder, consisting of a rear end cover 1, a return spring 4, an unlocking piston assembly 6, and a locking spring 9. High-pressure hydraulic oil pushes the unlocking piston assembly 6 to the left, and the unlocking piston assembly 6 pushes the locking block 7 into the piston's locking groove (second groove), thus achieving mechanical locking of the piston.

[0029] In one embodiment, refer to Figure 6 The buffer assembly includes a buffer piston 14, a pull rod 15, and a buffer spring 16. The second end of the piston assembly 8 has a partition inside. The pull rod 15 is vertically connected to the partition. The buffer piston 14 and the buffer spring 16 are sleeved on the pull rod 15. The buffer piston 14 is close to the second end of the piston assembly 8 and slides on the pull rod 15. One end of the buffer spring 16 abuts against the buffer piston 14, and the other end of the buffer spring 16 abuts against the partition. The side wall of the pull rod 15 has a first buffer damping hole, and the rear end face of the pull rod 15 has a second buffer damping hole. The first buffer damping hole and the second buffer damping hole communicate with each other.

[0030] Specifically, the end-buffer assembly consists of a buffer piston 14, a pull rod 15, etc., and is installed at the front end of the main piston via the pull rod 15. The buffer piston 14 fits with the inner hole of the main piston to ensure that the gap does not exceed 0.05mm, and the buffer piston 14 and the piston inner cavity form a sealed buffer chamber. When the piston retracts, the emergency piston assembly 5 contacts the buffer piston 14, preventing the buffer piston 14 from moving to the left, thereby compressing the buffer chamber space. The hydraulic oil in the buffer chamber will flow to the emergency chamber through the buffer damping holes 23 (including the first buffer damping hole and the second buffer damping hole) distributed on the pull rod 15, as shown in the figure. Figure 8 As shown.

[0031] Furthermore, the rear end face of the pull rod 15 is provided with a second protrusion, which limits the buffer piston 14.

[0032] In one embodiment, refer to Figure 7The cylinder assembly 11 is further provided with a positioning signal indication structure on the outside of the second end. The positioning signal indication structure includes a push rod 21, a proximity sensor 19 and a target 22. The push rod 21 is located in an inclined structure outside the cylinder assembly 11. One end of the push rod 21 extends into the inner wall of the cylinder assembly 11, and the other end of the push rod 21 is equipped with the target 22. The proximity sensor 19 is fixed on the outside of the cylinder assembly 11, and the sensing end of the proximity sensor 19 faces the target 22.

[0033] Specifically, the positioning signal indicator structure is designed on the cylinder assembly 11, consisting of a push rod 21, a proximity sensor 19, and a target 22 mounted on the cylinder assembly 11. When the actuator cylinder extends and the door is about to be fully extended, the piston assembly 8 pushes the push rod 21 outward, and the push rod 21 moves the target 22 closer to the proximity sensor 19. When fully extended, the target 22 enters the sensing distance of the proximity sensor 19, and the proximity sensor 19 outputs a positioning signal outward.

[0034] In one embodiment, a front lug 18 is threadedly connected to the port of the second end of the piston assembly 8, and the front lug 18 is fixed by a locking nut 17. A spherical bearing 2 is provided on both the rear end cover 1 and the front lug 18. The spherical bearing 2 on the rear end cover 1 and the spherical bearing 2 on the front lug 18 connect the overall structure to the aircraft door, ensuring flexibility in opening and closing the door.

[0035] Furthermore, a guide sleeve assembly 13 is provided between the port of the second end of the cylinder assembly 11 and the second end of the piston assembly 8, and a first seal is provided on the inner wall of the guide sleeve assembly 13.

[0036] Furthermore, the first end of the piston assembly 8 is provided with a second seal, and both ends of the emergency piston assembly 5 are provided with a third seal.

[0037] Furthermore, a fourth seal is provided between the cylinder assembly 11 and the outer wall, a fifth seal is provided between the unlocking piston assembly 6 and the inner wall, and a sixth seal is provided between the unlocking piston assembly 6 and the emergency piston assembly 5.

[0038] In specific implementation, refer to Figure 3 The main drive structure consists primarily of a rear end cover 1, a retraction nozzle 12, an extension nozzle 20, a cylinder assembly 11, seals, a piston assembly 8, and a guide sleeve assembly 13. The rear end cover 1 and guide sleeve assembly 13 are connected to the cylinder assembly 11 via threads and sealed with a sealing ring, forming a sealed extension / retraction working chamber. High-pressure oil is supplied through the emergency nozzle 3 and the retraction nozzle 12 to drive the piston assembly 8 to extend / retract. (Refer to...) Figure 5Emergency piston assembly 5 and piston assembly 8 constitute an emergency drive structure, which works in series with the main piston. Emergency nozzle 3 supplies high-pressure oil, which enters the emergency chamber of the actuator cylinder. The high-pressure oil pushes piston assembly 8 to extend to the right, and the oil in the retraction chamber is returned to the system through retraction nozzle 12.

[0039] The working principle of the integrated landing gear door retraction mechanism of this application is as follows: When the emergency nozzle 3 and the extension nozzle 20 are connected to the hydraulic power source, hydraulic oil enters the first end of the emergency piston assembly 5 through the emergency nozzle 3, pushing the piston assembly 8 to extend outward as a whole. At this time, the unlocking piston assembly 6 in the mechanical locking assembly moves towards the emergency nozzle 3 under the action of hydraulic pressure, overcoming the elastic force of the return spring 4. The locking block 7 separates from the second groove on the inner wall of the piston assembly 8, allowing the piston assembly 8 to extend freely. When the piston assembly 8 extends to the set position, the locking block 7, under the action of the locking spring 9, engages with the first groove on the emergency piston assembly 5, achieving mechanical locking and preventing the piston assembly 8 from retracting accidentally.

[0040] When the piston assembly 8 needs to retract, the hydraulic power source is connected through the retraction nozzle 20, and hydraulic oil enters the annular space formed by the cylinder assembly 11 and the piston assembly 8, pushing the piston assembly 8 to retract inward. At the same time, the buffer assembly starts to work, the buffer piston 14 slides on the pull rod 15, compressing the buffer spring 16, and the hydraulic oil flows out slowly through the first buffer damping hole and the second buffer damping hole, which plays a buffering role and prevents the piston assembly 8 from retracting too quickly and causing impact.

[0041] The position signal indicator structure is used to detect whether the piston assembly 8 has extended to the correct position. When the piston assembly 8 has extended to the correct position, the push rod 21 moves outward under the action of the inner wall of the cylinder assembly 8, causing the target 22 to move into the sensing range of the proximity sensor 19. The proximity sensor 19 then sends a position signal to the operator, indicating that the piston assembly 8 has extended to the correct position.

[0042] The guide sleeve assembly 13 is used to guide the extension and retraction movement of the piston assembly 8, ensuring the linearity of the piston assembly 8's movement. The first seal, second seal, third seal, fourth seal, fifth seal, and sixth seal are respectively located at different connection points, serving a sealing function to prevent hydraulic oil leakage and ensure the normal operation of the integrated landing gear door retraction mechanism.

[0043] The embodiments provided by this invention, through a highly integrated design, combine main drive, mechanical locking, end-effector buffer, emergency drive, and position signal indication functions into one unit, significantly improving the reliability and maintainability of the landing gear door retraction mechanism. Its core advantages are: the stepped cylinder structure and the tandem mechanical locking assembly achieve stable locking of the actuator cylinder under extreme conditions; the buffer assembly adopts a dual-damping orifice design, effectively controlling the impact force during piston retraction; and the position signal indication structure provides real-time feedback of position status through a non-contact sensor, ensuring operational safety. Furthermore, the modular sealing design (covering six key sealing areas) significantly reduces the risk of hydraulic system leakage, and combined with the linear motion guidance function of the guide sleeve assembly, the entire mechanism can maintain high-precision operation even in confined spaces.

[0044] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An integrated landing gear door retraction mechanism, characterized by, The application relates to a cylinder assembly (11), a first end of the cylinder assembly (11) is sealingly connected with a rear end cover (1), an emergency nozzle (3) and an extension nozzle (20) are arranged on the outside of the rear end cover (1), the connecting end of the rear end cover (1) and the cylinder assembly (11) is arranged as a stepped cylinder structure, the first end of the cylinder assembly (11) is located in the inside of the stepped cylinder structure, the outside of the second end of the cylinder assembly (11) is provided with a retraction nozzle (12), the inside of the cylinder assembly (11) is provided with a piston assembly (8), the inside of the first end of the piston assembly (8) is provided with a mechanical locking assembly, the middle shaft area of the piston assembly (8) is provided with an emergency piston assembly (5), the mechanical locking assembly is located between the piston assembly (8) and the emergency piston assembly (5), the emergency piston assembly (5) is a hollow structure, the emergency nozzle (3) is communicated with the first end of the emergency piston assembly (5); the second end of the piston assembly (8) extends out of the cylinder assembly (11), and the inside of the second end of the piston assembly (8) is provided with a buffer assembly, the buffer assembly is located at the second end of the emergency piston assembly (5).

2. The integrated landing gear door retraction mechanism of claim 1, wherein, The stepped cylinder structure of the rear end cover (1) is provided with an outer wall and an inner wall, the first end of the cylinder assembly (11) and the first end of the piston assembly (8) are located between the outer wall and the inner wall, and the mechanical locking assembly and the emergency piston assembly (5) are located on the inside of the inner wall.

3. An integrated landing gear door retraction mechanism according to claim 2, wherein, The mechanical locking assembly comprises an unlocking piston assembly (6), a locking block (7), a reset spring (4), a locking spring (9) and a spring seat (10), the unlocking piston assembly (6) is located between the inner wall and the emergency piston assembly (5), the end of the unlocking piston assembly (6) close to the emergency nozzle (3) is provided with the reset spring (4), the end of the unlocking piston assembly (6) away from the emergency nozzle (3) is provided with the locking spring (9), the locking spring (9) is fixed on the piston assembly (8) through the spring seat (10), the locking block (7) is arranged on the inner wall, the position of the locking block (7) corresponds to the position of the emergency piston assembly (5), the emergency piston assembly (5) is provided with a first recess and a first protrusion, the inner wall of the piston assembly (8) is provided with a second recess, the locking block (7) and the first recess are matched to realize unlocking of the piston assembly (8), and the locking block (7) and the second recess are matched to realize locking of the piston assembly (8).

4. The integrated landing gear door retraction mechanism of claim 1, wherein, The buffer assembly comprises a buffer piston (14), a pull rod (15) and a buffer spring (16), the inside of the second end of the piston assembly (8) is provided with a partition layer, the pull rod (15) is vertically connected to the partition layer, the buffer piston (14) and the buffer spring (16) are sleeved on the pull rod (15), the buffer piston (14) is close to the second end of the piston assembly (8), the buffer piston (14) slides on the pull rod (15), one end of the buffer spring (16) abuts against the buffer piston (14), the other end of the buffer spring (16) abuts against the partition layer, the sidewall of the pull rod (15) is provided with a first buffer damping hole, and the rear end surface of the pull rod (15) is provided with a second buffer damping hole, the first buffer damping hole and the second buffer damping hole are communicated.

5. An integrated landing gear door retraction mechanism according to claim 4, wherein, The rear end surface of the pull rod (15) is provided with a second protrusion, and the buffer piston (14) is limited by the second protrusion.

6. The integrated landing gear door retraction mechanism of Claim 1, wherein, The outer part of the second end of the cylinder assembly (11) is further provided with a to-position signal indicating structure, which comprises a push rod (21), a proximity sensor (19) and a target (22), the push rod (21) is located in the inclined structure outside the cylinder assembly (11), one end of the push rod (21) extends into the inner wall of the cylinder assembly (11), the other end of the push rod (21) is provided with the target (22), and the proximity sensor (19) is fixed outside the cylinder assembly (11), and the sensing end of the proximity sensor (19) faces the target (22).

7. The integrated landing gear door retraction mechanism of Claim 1, wherein, The port of the second end of the piston assembly (8) is threadedly connected with a front end ear ring (18), and the front end ear ring (18) is fixed through a locking nut (17).

8. The integrated landing gear door retraction mechanism of Claim 1, wherein, A guide sleeve assembly (13) is arranged between the port of the second end of the cylinder assembly (11) and the second end of the piston assembly (8), and a first sealing element is arranged on the inner wall of the guide sleeve assembly (13).

9. The integrated landing gear door retraction mechanism of Claim 1, wherein, The first end of the piston assembly (8) is provided with a second sealing element, and the two ends of the emergency piston assembly (5) are provided with third sealing elements.

10. The integrated landing gear door retraction mechanism of Claim 2, wherein, A fourth sealing element is arranged between the cylinder assembly (11) and the outer layer wall, a fifth sealing element is arranged between the unlocking piston assembly (6) and the inner layer wall, and a sixth sealing element is arranged between the unlocking piston assembly (6) and the emergency piston assembly (5).

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