Lifting actuation system for a main cargo door of a cargo aircraft and cargo aircraft

Abstract

The utility model relates to a lifting actuating system for main cargo compartment door of freighter and freighter, the lifting actuating system for main cargo compartment door of freighter includes actuating cylinder, motor pump, hydraulic oil tank, connecting rod mechanism, controller, actuating cylinder is installed in main cargo compartment, motor pump, hydraulic oil tank and controller are installed in the escort cabin of main cargo compartment front, the controller is connected to motor pump with the aid of cable to be used for controlling the start and stop of motor pump, motor pump is connected to hydraulic oil tank, hydraulic oil tank is connected to actuating cylinder with the aid of hydraulic pipeline, actuating cylinder is connected to main cargo compartment door with the aid of connecting rod mechanism, in normal working mode, the controller controls motor pump and starts, sends hydraulic oil in hydraulic oil tank to actuating cylinder to establish first pressure difference in the two cavities of actuating cylinder, pushes out the piston rod of actuating cylinder, drives connecting rod mechanism to rotate upwards around corresponding hinge on main cargo compartment door, makes main cargo compartment door open upwards, and makes main cargo compartment door close downwards by analogy.

Description

Technical Field

[0001] This utility model relates to a lifting actuation system for the main cargo door of a cargo aircraft and an aircraft including the lifting actuation system for the main cargo door of a cargo aircraft. Background Technology

[0002] A freighter is an aircraft specifically designed for transporting cargo. Most freighters today are converted from commercial passenger aircraft that have been in operation for a certain number of years. The original passenger cabin is converted into the main cargo hold for loading cargo containers. When converting a passenger aircraft into a freighter, large openings need to be cut into the fuselage structure for rapid entry and exit and loading of large cargo containers. An additional main cargo door and its lifting actuation system are also added. The lifting actuation system is located between the door structure and the container, and is used to open and close the door. Because the space in the main cargo hold of narrow-body mainline freighters is very limited, the motion envelope space of the lifting actuation system must be kept very small; otherwise, it will affect the entry, exit, and loading of cargo containers, reducing the cargo volume of the main cargo hold.

[0003] Currently, most mainstream narrow-body mainline freighters use hydraulic linear actuation for their cargo door lifting systems, which offers advantages such as a small motion envelope and high reliability. This hydraulic lifting system needs to be integrated with the existing passenger aircraft's hydraulic system, requiring piping to be laid from the main landing gear bay to guide hydraulic oil to the actuator cylinder above the main cargo door in the forward fuselage. This approach adds a significant amount of weight to the hydraulic piping, affects a wider area, and increases the risk of hydraulic oil leaks. Utility Model Content

[0004] One objective of this invention is to provide a lifting actuation system for the main cargo door of a cargo aircraft, which overcomes at least some of the defects of the prior art, reduces hydraulic lines, lightens system weight, and reduces the risk of hydraulic oil leakage.

[0005] The above-mentioned objectives of this utility model are achieved by a lifting actuation system for the main cargo door of a cargo aircraft, the lifting actuation system for the main cargo door of a cargo aircraft including an actuating cylinder, a motor pump, a hydraulic oil tank, a linkage mechanism, and a controller.

[0006] The actuator is installed in the main cargo hold, and the motor pump, the hydraulic oil tank and the controller are installed in the escort compartment in front of the main cargo hold.

[0007] The controller is connected to the motor pump via a cable to control the start and stop of the motor pump. The motor pump is connected to the hydraulic oil tank. The hydraulic oil tank is connected to the actuator via a hydraulic line. The actuator is connected to the main cargo door via a linkage mechanism.

[0008] In normal operating mode, the controller starts the motor pump to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a first pressure difference between the two chambers of the actuator. This pressure difference pushes the piston rod of the actuator to extend, driving the linkage mechanism to rotate upward around the corresponding hinge on the main cargo door, thus opening the main cargo door upward. Alternatively, the controller starts the motor pump to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a second pressure difference between the two chambers of the actuator. This pressure difference pushes the piston rod of the actuator to retract, driving the linkage mechanism to rotate downward around the corresponding hinge on the main cargo door, thus closing the main cargo door downward.

[0009] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: reduce hydraulic pipelines, reduce system weight, and reduce the risk of hydraulic oil leakage; reduce the possibility of interference and reduce the amount of modification required for adaptive avoidance of the fuselage structure.

[0010] Preferably, the hydraulic oil tank is a hydraulic oil tank independent of the main landing gear hydraulic system.

[0011] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: the electro-hydraulic actuation system has its own oil tank, eliminating the need to draw hydraulic oil from the original passenger aircraft's hydraulic system, reducing hydraulic pipelines, reducing system weight, and reducing the risk of hydraulic oil leakage.

[0012] Preferably, the lifting actuation system for the main cargo door of the cargo aircraft also includes a hand pump, which is also installed in the escort compartment in front of the main cargo compartment and is also connected to the hydraulic oil tank.

[0013] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: in the event of motor pump failure, the hand pump does not need to draw hydraulic oil from the main landing gear bay, reducing hydraulic lines, reducing system weight, and this position makes it easier to observe the door opening status during manual operation.

[0014] Preferably, in the motor pump failure mode, the hand-cranked pump is turned to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a first pressure difference between the two chambers of the actuator, pushing the piston rod of the actuator to extend, and driving the linkage mechanism to rotate upward around the corresponding hinge on the main cargo door, thereby opening the main cargo door upward; or the hand-cranked pump is turned to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a second pressure difference between the two chambers of the actuator, pushing the piston rod of the actuator to retract, and driving the linkage mechanism to rotate downward around the corresponding hinge on the main cargo door, thereby closing the main cargo door downward.

[0015] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: in the event of motor pump failure, the opening / closing of the main cargo door can be better realized by the appropriate arrangement of the hand pump.

[0016] Preferably, the lifting actuation system for the main cargo door of a cargo aircraft also includes a hydraulic lock connected to the two chambers of the actuating cylinder. In normal operating mode, when the main cargo door opens upward and reaches the predetermined position sensor, the controller controls the motor pump to stop working, and the two chambers of the actuating cylinder are locked by the hydraulic lock, keeping the main cargo door in the current position and completing the opening of the main cargo door.

[0017] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: it can lock the position of the main cargo door in time when the main cargo door is opened to the predetermined position, so as to prevent the main cargo door from being over-opened.

[0018] Preferably, the actuator is mounted on a long bar beneath the fuselage skin inside the main cargo compartment.

[0019] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: by appropriately installing the actuating cylinder, the hydraulic pipeline can be reduced, the system weight can be reduced, and the possibility of interference can be reduced.

[0020] Preferably, the motor pump and the hydraulic oil tank are installed under the fuselage skin inside the escort compartment.

[0021] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: by appropriately installing the motor pump and hydraulic oil tank, the hydraulic pipeline is reduced, the system weight is reduced, and the possibility of interference is reduced.

[0022] Preferably, the controller is installed near the aircraft boarding gate inside the escort compartment.

[0023] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: the appropriate installation position of the controller facilitates operation by the operators.

[0024] Preferably, the hand-cranked pump is installed near the aircraft boarding door inside the escort compartment.

[0025] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: by appropriately installing the hand pump, the hydraulic pipeline can be reduced, the system weight can be reduced, and it is easier for operators to operate.

[0026] The above-mentioned objectives of this utility model are also achieved by a cargo aircraft, which includes a lifting actuation system for the main cargo door of the cargo aircraft as described in any of the above aspects.

[0027] According to the above technical solution, the aircraft of this utility model can achieve the following beneficial technical effects: reduce hydraulic pipelines, reduce system weight, and reduce the risk of hydraulic oil leakage; reduce the possibility of interference and reduce the amount of modification required for adaptive avoidance of the fuselage structure. Attached Figure Description

[0028] Figure 1 This is an overall layout diagram of a lifting actuation system for the main cargo door of a cargo aircraft according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of a lifting actuation system for the main cargo door of a cargo aircraft according to an embodiment of the present invention.

[0030] List of reference numerals

[0031] 10: Improve the actuation system;

[0032] 11: Actuator;

[0033] 12: Electric motor pump;

[0034] 13: Hydraulic oil tank;

[0035] 14: Linkage mechanism;

[0036] 15: Hand-cranked pump;

[0037] 16: Controller;

[0038] 17: Cable;

[0039] 18: Hydraulic pipelines;

[0040] 20: Fuselage;

[0041] 30: Main cargo door;

[0042] 40: Hinges;

[0043] 50: Container;

[0044] 60: Long stringer;

[0045] C: Heading;

[0046] S: Expansion direction. Detailed Implementation

[0047] The following describes specific embodiments of this utility model. It should be noted that, in order to provide a concise description, this specification cannot provide a detailed description of all features of the actual embodiments. It should be understood that, in the actual implementation of any embodiment, just as in any engineering or design project, various specific decisions are often made to achieve the developer's specific goals and to meet system-related or business-related constraints, and this can change from one embodiment to another. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this utility model, some design, manufacturing, or production modifications based on the technical content disclosed in this disclosure are merely conventional technical means and should not be construed as insufficient content of this disclosure.

[0048] Unless otherwise defined, the technical or scientific terms used in the claims and description shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar words used in the specification and claims of this utility model patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar words do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar words mean that the element or object preceding "comprising" or "including" encompasses the element or object listed following "comprising" or "including" and its equivalents, and do not exclude other elements or objects. The terms "connected" or "linked" and similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0049] In the following description, in order to clearly demonstrate the structure and working method of this utility model, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0050] Figure 1 This is an overall layout diagram of a lifting actuation system for the main cargo door of a cargo aircraft according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a lifting actuation system for the main cargo door of a cargo aircraft according to an embodiment of the present invention.

[0051] like Figures 1 to 2 As shown, according to some embodiments of the present invention, the lifting actuation system 10 for the main cargo door of a cargo aircraft includes an actuating cylinder 11, a motor pump 12, a hydraulic oil tank 13, a linkage mechanism 14, and a controller 16.

[0052] The actuator 11 is installed in the main cargo hold, while the motor pump 12, hydraulic oil tank 13, and controller 16 are installed in the escort compartment in front of the main cargo hold.

[0053] The controller 16 is connected to the motor pump 12 via cable 17 to control the start and stop of the motor pump 12. The motor pump 12 is connected to the hydraulic oil tank 13. The hydraulic oil tank 13 is connected to the actuator 11 via hydraulic line 18. The actuator 11 is connected to the main cargo door 30 via linkage mechanism 14.

[0054] In normal operating mode, the controller 16 controls (e.g., the operator operates the control button on the controller 16) to start the motor pump 12, which delivers hydraulic oil from the hydraulic tank 13 to the actuator cylinder 11, establishing a first pressure difference between the two chambers of the actuator cylinder 11. This pushes the piston rod of the actuator cylinder 11 to extend, driving the linkage mechanism 14 to rotate upward around the corresponding hinge 40 on the main cargo door 30, thus opening the main cargo door 30 upward. Alternatively, the controller 16 controls the motor pump 12 to start, delivering hydraulic oil from the hydraulic tank 13 to the actuator cylinder 11, establishing a second pressure difference between the two chambers of the actuator cylinder 11. This pushes the piston rod of the actuator cylinder 11 to retract, driving the linkage mechanism 14 to rotate downward around the corresponding hinge 40 on the main cargo door 30, thus closing the main cargo door 30 downward.

[0055] According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: reduce hydraulic pipelines, reduce system weight, and reduce the risk of hydraulic oil leakage; reduce the possibility of interference and reduce the amount of modification required for adaptive avoidance of the fuselage structure.

[0056] Specifically, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model adopts an electro-hydraulic actuator. The electro-hydraulic actuator mainly includes an actuator cylinder 11, a motor pump 12, and a hydraulic oil tank 13. Since the electro-hydraulic actuator has its own hydraulic oil tank, it is not necessary to draw hydraulic oil from the original passenger aircraft's hydraulic system (such as the main landing gear hydraulic system), which reduces the hydraulic pipeline, lightens the system weight, and reduces the risk of hydraulic oil leakage.

[0057] The motor pump 12, hydraulic oil tank 13 and actuator cylinder 11 of the electro-hydraulic actuator are separated and arranged in other compartments (escort compartments) with more space. Only the actuator cylinder 11 needs to be arranged at the narrowest gap between the container 50 and the structural frame, which increases the clearance margin around the actuator, reduces the possibility of interference, and reduces the amount of modification required for the fuselage structure to adapt and avoid obstacles.

[0058] In some embodiments, such as Figures 1 to 2 As shown, the electro-hydraulic actuator outputs linear force to drive the piston rod of the actuator cylinder 11 to extend or retract, thereby driving the linkage mechanism 14 to rotate upward or downward around the hinge 40, converting the linear motion and force of the actuator cylinder 11 into rotational motion and torque. The actuator cylinder 11 typically includes a cylinder body and a piston rod. The pressure difference between the two chambers within the actuator cylinder body can push the piston rod of the actuator cylinder 11 to extend or retract.

[0059] The establishment of a first pressure difference between the two chambers of the actuator cylinder 11 means that the pressure in the first chamber of the actuator cylinder 11 (e.g., the chamber near the actuator cylinder mounting point on the fuselage) is higher than the pressure in the second chamber of the actuator cylinder 11 (e.g., the chamber far from the actuator cylinder mounting point on the fuselage). This first pressure difference pushes the piston rod of the actuator cylinder 11 to extend, driving the linkage mechanism 14 to rotate upwards around the corresponding hinge 40 on the main cargo door 30, thus opening the main cargo door 30 upwards. The establishment of a second pressure difference between the two chambers of the actuator cylinder 11 means that the pressure in the second chamber of the actuator cylinder 11 (e.g., the chamber far from the actuator cylinder mounting point on the fuselage) is higher than the pressure in the first chamber of the actuator cylinder 11 (e.g., the chamber near the actuator cylinder mounting point on the fuselage). This second pressure difference pushes the piston rod of the actuator cylinder 11 to retract, driving the linkage mechanism 14 to rotate downwards around the corresponding hinge 40 on the main cargo door 30, thus closing the main cargo door 30 downwards.

[0060] Preferably, the end of the actuator 11 (near the actuator mounting point on the fuselage) can be connected to the door frame structure of the main cargo door 30 by adding a tie rod structure, so as to transfer the load of the main cargo door 30 to the door frame structure and reduce the stress concentration of the fuselage structural stringer.

[0061] In some embodiments, such as Figure 1 As shown, the main cargo door 30 is located at the front of the fuselage 20 to prevent the loading platform vehicle from scraping the wing when docking with the door.

[0062] In some embodiments, such as Figure 2 As shown, the linkage mechanism 14 includes multiple links and pins, arranged near the corresponding hinges 40 on the main cargo door 30. The main function of the linkage mechanism 14 is to convert the linear actuation force output from the actuator 11 into a rotational torque around the hinge 40, driving the main cargo door 30 to open and close. Preferably, the hinge 40 is a piano key hinge, for example, installed at the connection between the main cargo door 30 and the fuselage 20.

[0063] In some embodiments, such as Figures 1 to 2 As shown, the hydraulic oil tank 13 is independent of the main landing gear hydraulic system. According to the above technical solution, the lifting actuation system for the main cargo door of this utility model achieves the following beneficial technical effects: the electro-hydraulic actuation system has its own oil tank, eliminating the need to draw hydraulic oil from the original passenger aircraft's hydraulic system, reducing hydraulic lines, lightening system weight, and reducing the risk of hydraulic oil leakage. Therefore, compared to the hydraulic oil tank of the main landing gear hydraulic system, the hydraulic oil tank 13 used in the lifting actuation system for the main cargo door of this utility model can also be called a small hydraulic oil tank.

[0064] In some embodiments, such as Figure 1 As shown, the lifting actuation system 10 for the main cargo hold door of a cargo aircraft also includes a hand pump 15, which is also installed in the escort compartment in front of the main cargo hold and is connected to the hydraulic oil tank 13. According to the above technical solution, the lifting actuation system for the main cargo hold door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: In the event of failure of the motor pump 12, the hand pump 15 does not need to draw hydraulic oil from the main landing gear bay, reducing hydraulic lines, reducing system weight, and this position makes it easier to observe the door opening status during manual operation.

[0065] In some embodiments, such as Figures 1 to 2 As shown, in the motor pump failure mode, the hand pump 15 is cranked to deliver hydraulic oil from the hydraulic oil tank 13 to the actuator cylinder 11, establishing a first pressure difference between the two chambers of the actuator cylinder 11. This pushes the piston rod of the actuator cylinder 11 to extend, driving the linkage mechanism 14 to rotate upward around the corresponding hinge 40 on the main cargo door 30, thus opening the main cargo door 30 upward. Alternatively, the hand pump 15 is cranked to deliver hydraulic oil from the hydraulic oil tank 13 to the actuator cylinder 11, establishing a second pressure difference between the two chambers of the actuator cylinder 11. This pushes the piston rod of the actuator cylinder 11 to retract, driving the linkage mechanism 14 to rotate downward around the corresponding hinge 40 on the main cargo door 30, thus closing the main cargo door 30 downward. According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: in the event of motor pump 12 failure, the opening / closing of the main cargo door 30 can be better achieved through the appropriate arrangement of the hand pump 15.

[0066] Preferably, after the main cargo door 30 has moved to the expected position, the operators stop turning the hand pump 15 and confirm that the main cargo door 30 is securely fixed. At this point, the cargo container 50 inside the main cargo hold can be unloaded, and the main cargo door actuation system can be repaired and restored to normal operation.

[0067] In some embodiments, such as Figures 1 to 2 As shown, the lifting actuation system 10 for the main cargo door of a cargo aircraft also includes a hydraulic lock. The hydraulic lock is connected to the two chambers of the actuation cylinder 11. In normal operating mode, when the main cargo door 30 opens upward and reaches the predetermined position sensor, the controller 16 controls the motor pump 12 to stop working, and the two chambers of the actuation cylinder 11 are locked by the hydraulic lock, holding the main cargo door 30 in the current position, thus completing the opening of the main cargo door 30. According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: it can lock the position of the main cargo door 30 in time when it opens to the predetermined position, preventing the main cargo door 30 from being over-opened.

[0068] In some embodiments, such as Figure 2 As shown, the actuator 11 (e.g., via a support) is mounted on the stringer 60 below the skin of the fuselage 20 inside the main cargo hold. According to the above technical solution, the lifting actuation system for the main cargo hold door of a cargo aircraft of this invention can achieve the following beneficial technical effects: by appropriately installing the actuator 11, hydraulic lines are reduced, system weight is reduced, and the possibility of interference is decreased.

[0069] Preferably, the actuator 11 is installed on top of the container 50 inside the main cargo hold. In this distributed arrangement, the top of the main cargo hold only needs to accommodate the elongated actuator 11 and the linkage mechanism 14, avoiding problems of insufficient clearance and arrangement interference.

[0070] In some embodiments, such as Figures 1 to 2 As shown, the motor pump 12 and hydraulic oil tank 13 are installed under the skin of the fuselage 20 inside the cargo compartment. According to the above technical solution, the lifting actuation system for the main cargo door of this utility model can achieve the following beneficial technical effects: by appropriately installing the motor pump 12 and hydraulic oil tank 13, the hydraulic pipeline is reduced, the system weight is lightened, and the possibility of interference is lowered.

[0071] In some embodiments, such as Figure 1 As shown, the controller 16 is installed near the aircraft boarding door inside the escort compartment. According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: the appropriate installation position of the controller 16 facilitates operation by personnel.

[0072] Preferably, the controller 16 is used by operators to open and close the main cargo door 30. The controller panel is equipped with operation buttons, levers, and door status indicator lights. The controller 16 controls the motor pump 12 of the electro-hydraulic actuator via cable 17, and can also receive signals from the door sensor and the crosslinking system.

[0073] In some embodiments, such as Figure 1 As shown, the hand pump 15 is installed near the aircraft boarding door inside the cargo hold. According to the above technical solution, the lifting actuation system for the main cargo door of a cargo aircraft of this utility model can achieve the following beneficial technical effects: the appropriate installation position of the hand pump 15 better reduces hydraulic lines, lightens the system weight, and facilitates operation by personnel.

[0074] Preferably, the hand-cranked pump 15 is installed on the emergency barrier wall near the aircraft boarding door inside the escort compartment.

[0075] According to one embodiment of the present invention, a cargo aircraft includes a lifting actuation system 10 for the main cargo door of the cargo aircraft as described in any of the above aspects. Based on the above technical solution, the cargo aircraft of the present invention can achieve the following beneficial technical effects: it reduces hydraulic lines, lightens the system weight, and reduces the risk of hydraulic oil leakage; it reduces the possibility of interference and the amount of modification required for adaptive avoidance of the fuselage structure.

[0076] The specific embodiments of this utility model have been described above. However, those skilled in the art will understand that the above specific embodiments do not constitute a limitation on this utility model. Those skilled in the art can make various modifications based on the above disclosure without exceeding the scope of this utility model.

Claims

1. A lifting actuation system for the main cargo door of a cargo aircraft, characterized in that, The lifting actuation system for the main cargo door of a cargo aircraft includes an actuating cylinder, a motor pump, a hydraulic oil tank, a linkage mechanism, and a controller. The actuator is installed in the main cargo hold, and the motor pump, the hydraulic oil tank and the controller are installed in the escort compartment in front of the main cargo hold. The controller is connected to the motor pump via a cable to control the start and stop of the motor pump. The motor pump is connected to the hydraulic oil tank. The hydraulic oil tank is connected to the actuator via a hydraulic line. The actuator is connected to the main cargo door via a linkage mechanism. In normal operating mode, the controller starts the motor pump to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a first pressure difference between the two chambers of the actuator. This pressure difference pushes the piston rod of the actuator to extend, driving the linkage mechanism to rotate upward around the corresponding hinge on the main cargo door, thus opening the main cargo door upward. Alternatively, the controller starts the motor pump to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a second pressure difference between the two chambers of the actuator. This pressure difference pushes the piston rod of the actuator to retract, driving the linkage mechanism to rotate downward around the corresponding hinge on the main cargo door, thus closing the main cargo door downward.

2. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 1, characterized in that, The hydraulic oil tank is independent of the main landing gear hydraulic system.

3. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 1, characterized in that, The lifting actuation system for the main cargo door of the cargo aircraft also includes a hand pump, which is also installed in the escort compartment in front of the main cargo door and is connected to the hydraulic oil tank.

4. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 3, characterized in that, In the motor pump failure mode, the hand pump is cranked to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a first pressure difference between the two chambers of the actuator. This pushes the piston rod of the actuator to extend, driving the linkage mechanism to rotate upward around the corresponding hinge on the main cargo door, causing the main cargo door to open upward. Alternatively, the hand pump is cranked to deliver hydraulic oil from the hydraulic tank to the actuator, establishing a second pressure difference between the two chambers of the actuator. This pushes the piston rod of the actuator to retract, driving the linkage mechanism to rotate downward around the corresponding hinge on the main cargo door, causing the main cargo door to close downward.

5. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 1, characterized in that, The lifting actuation system for the main cargo door of a cargo aircraft also includes a hydraulic lock connected to the two chambers of the actuating cylinder. In normal operation, when the main cargo door opens upward and reaches the predetermined position sensor, the controller controls the motor pump to stop working, and the two chambers of the actuating cylinder are locked by the hydraulic lock, keeping the main cargo door in the current position and completing the opening of the main cargo door.

6. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 1, characterized in that, The actuator is mounted on the long bar beneath the fuselage skin inside the main cargo hold.

7. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 1, characterized in that, The motor pump and the hydraulic oil tank are installed under the fuselage skin inside the escort compartment.

8. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 1, characterized in that, The controller is installed near the aircraft boarding gate inside the escort compartment.

9. The lifting actuation system for the main cargo door of a cargo aircraft as described in claim 3, characterized in that, The hand-cranked pump is installed near the aircraft boarding door inside the escort compartment.

10. A cargo aircraft, comprising a lifting actuation system for the main cargo door of the cargo aircraft as claimed in any one of claims 1-9.

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