Freight unmanned aerial vehicle cargo hold tail door actuation system and control method

Abstract

The invention relates to the technical field of aircrafts, in particular to a freight unmanned aerial vehicle cargo hold tail door actuation system and a control method, and the actuation system comprises a door frame, a first cabin door, at least two second cabin doors, a lifting mechanism and a split mechanism. Specifically, the door frame is arranged on the periphery of an opening of a stern room; the first cabin door is hinged to one end of the door frame and used for closing the tail cabin opening close to the nose. The two second cabin doors are hinged to the two sides of the door frame in an oppositely-opened state correspondingly and used for closing the remaining part of the tail cabin opening; the lifting mechanism is used for controlling the first cabin door to be opened or closed and can be opened by a maximum angle when the first cabin door abuts against the ground or is limited by an external object, and the situation that the lifting mechanism is overloaded and damaged or continuously drives the first cabin door to be opened to cause damage to the cabin door or the fuselage is prevented. The opposite opening mechanism is used for driving the two second cabin doors to be opened or closed. The tail cabin door has the effects that the operation stability of the tail cabin door is improved, and damage to the tail cabin door or a fuselage when the tail cabin door is opened is reduced.

Description

Technical Field

[0001] This application relates to the field of aircraft technology, and in particular to a cargo hold tail door actuation system and control method for a cargo drone. Background Technology

[0002] In the field of aircraft technology, the design of cargo aircraft doors is crucial, directly impacting cargo loading and unloading efficiency and the ease of aircraft use. Cargo aircraft doors are generally divided into two categories: side doors and rear doors. Side doors are located on the side of the fuselage. While their structure is simple, they suffer from low loading and unloading efficiency (cargo needs to be transferred laterally), poor spatial adaptability (easily interfered with by airport jet bridges or equipment when open), and difficulty in accommodating large cargo due to fuselage curvature. In contrast, rear doors are located on the underside of the aircraft's tail. When opened, they create a ramp that runs through the cargo hold, supporting a roller system for straight loading and unloading of cargo, significantly improving efficiency. Furthermore, the vertical opening avoids lateral space occupation and can cover the entire rear cargo hold section to accommodate standard containers and large equipment. Therefore, modern cargo aircraft have widely adopted rear door designs, gradually becoming the industry mainstream.

[0003] In related technologies, such as the aircraft cabin door inward opening mechanism disclosed in the patent with authorization announcement number CN117550059A, there are components such as cabin door, connecting support, adjusting linkage, actuator cylinder and connecting body, which drive the opening and closing of the cabin door through the actuator cylinder.

[0004] However, the existing tail hatch opening mechanism has significant drawbacks. When opening the hatch, the actuator continuously pushes it closer to the ground. If the actuator fails to stop promptly after contact with the ground, it is highly susceptible to overload damage. Furthermore, the continuous expansion of the actuator can damage the hatch and fuselage, potentially even breaking them. In actual operation, it is difficult to precisely control the critical point at which the actuator stops after the hatch contacts the ground. This creates a significant safety hazard during tail hatch operation and reduces its operational stability. Summary of the Invention

[0005] In order to improve the stability of the tail door operation and reduce the damage to the tail door itself or the fuselage when the tail door is opened, this application provides a cargo hold tail door actuation system and control method for a cargo UAV.

[0006] The cargo hold tail door actuation system for a cargo drone provided in this application adopts the following technical solution: A cargo hold tail door actuation system for a cargo drone includes: Door frames are located around the opening of the rear compartment; The first hatch is hinged to the end of the door frame near the nose of the aircraft and is used to close a portion of the tail hatch opening. At least two second hatches, which are hinged to each other on both sides of the door frame in a doubly open state, are used to close the remaining area of ​​the stern hatch opening; The lifting mechanism includes a connecting seat, a lead screw, a nut, multiple balls, a movable seat, a first actuator, and a limiting connector. The connecting seat is fixed to the door frame and has a first through hole. One end of the lead screw is hinged to a first hatch, and the other end extends upward through the first through hole. The nut is mounted on the lead screw, and multiple balls are disposed between the nut and the lead screw to form a ball screw pair. The movable seat is located on the side of the connecting seat away from the end of the lead screw that is hinged to the first hatch, and slides against the inner wall of the stern compartment. The movable seat is rotatably connected to the nut, and the first actuator drives the nut to rotate. The limiting connector is mounted on the movable seat and can restrict the movable seat from moving towards the first hatch along the central axis of the lead screw when the movable seat moves closer to the connecting seat to a predetermined distance. A split-opening mechanism is used to drive two second doors to open away from each other or close together.

[0007] By adopting the above technical solution, the stability of the tail hatch operation can be improved, and the damage to the tail hatch itself or the fuselage caused by the tail hatch opening can be reduced. Specifically, when opening the tail hatch, the first actuator drives the nut to rotate forward, causing the moving seat to slide relative to the lead screw along the rotation axis of the lead screw, and moving the moving seat away from the first hatch. During this process, the first hatch flips downward under its own weight, which in turn drives the moving seat closer to the connecting seat until the moving seat is restricted by the limiting connector, so that the position of the moving seat and the tail hatch is relatively fixed. The first hatch drives the lead screw to move closer to the ground and open the tail hatch opening to the part of the area near the nose of the fuselage. When the first hatch touches the ground or is limited to the maximum opening angle by an external object, and the first actuator continues to drive the nut to rotate forward, the position of the lead screw relative to the tail hatch is relatively fixed. The moving seat can move along the central axis of the lead screw away from the first hatch and the moving seat on the inner wall of the tail hatch under the drive of the nut, thereby preventing the first actuator from being overloaded or continuously driving the first hatch to open, which would cause damage to the first hatch or the fuselage. Then, the opening mechanism is controlled to drive the two second hatches to rotate outwards from their respective hinge points with the door frame, moving them away from each other and opening the remaining area of ​​the tail section. When closing the hatches, the first actuator is first controlled to reverse the nut, causing the moving seat to slide relative to the lead screw along its rotation axis, bringing the moving seat and the first hatch closer together. During this process, the first hatch, under its own weight, moves the moving seat closer to the connecting seat until the moving seat is restricted by the limiting connector, fixing its position relative to the tail section. The first hatch, along with the lead screw, moves away from the ground, closing the portion of the tail section opening near the nose. Then, the opening mechanism is controlled to drive the two second hatches to rotate inwards from their respective hinge points with the door frame, moving them closer together and closing the remaining area of ​​the tail section opening near the tail section.

[0008] Optionally, the limiting connector includes a spherical bearing, the inner ring of which is fixedly connected to the movable seat, and the outer ring of which is coaxially slidably disposed in the first through hole. The first through hole is provided with a boss for abutting against the side of the outer ring of the spherical bearing near the first hatch.

[0009] By adopting the above technical solution, the lead screw will deflect or rotate in multiple directions during the opening and closing of the first hatch. The spherical bearing can limit the relative position of the lead screw and the connecting seat to a certain extent while avoiding limiting the deflection or rotation of the lead screw, thus ensuring the flexibility of the lead screw during movement and making the opening and closing of the first hatch smoother, avoiding damage to the lifting mechanism caused by excessive restriction of the lead screw's degree of freedom. Furthermore, when the moving seat moves closer to the connecting seat to a predetermined distance, the outer ring of the spherical bearing can abut against the boss to limit the movement of the moving seat along the central axis of the lead screw towards the first hatch; when the moving seat moves away from the connecting seat, the spherical bearing can slide within the first through hole.

[0010] Optionally, the splitting mechanism includes a rotating rod, at least two connecting rods, and a driving component. The rotating rod is rotatably connected to the inner wall of the stern compartment. The first ends of the two connecting rods are rotatably connected to two second hatches, and the second ends of the two connecting rods are rotatably connected to the two ends of the rotating rod. The driving component is used to drive the rotating rod to rotate, so as to move the second ends of the two connecting rods closer to or further away from each other.

[0011] By adopting the above technical solution, the rotating rod is driven by the driving component to rotate, thereby causing the two connecting rods to pull the two second doors closer to each other or push the two second doors away from each other. This allows for flexible control of the two second doors to close or open the tail hatch opening near the tail of the aircraft.

[0012] Optionally, a locking mechanism is also included, comprising a first locking lug, a second locking lug, a slide rod, a locking pin, and a second actuator. The first locking lug is disposed on the door frame and has a first locking hole for the locking pin to be inserted into. The second locking lug is disposed on the first hatch and has a second locking hole for the locking pin to be inserted into. The slide rod is slidably disposed on the first hatch and the locking pin is disposed on the slide rod. The second actuator is used to drive the slide rod to slide. When the first hatch is closed, the first locking hole and the second locking hole can be coaxial, and the sliding of the slide rod can drive the locking pin to simultaneously insert into the first locking hole and the second locking hole or move out of the first locking hole.

[0013] By adopting the above technical solution, when the first door is closed, the first and second locking holes are coaxial. The second actuator drives the slide bar to slide, causing the locking pin to simultaneously insert into the first and second locking holes, thus reliably locking the first door onto the door frame. At this time, the weight of the first door, originally borne by the lifting mechanism, can be transferred to the locking mechanism, thereby relieving the lifting mechanism of its load-bearing capacity on the first door. Because the load from continuous bearing is reduced, the stress and wear on components in the lifting mechanism, such as the connecting seat, ball screw, moving seat, and first actuator, are reduced, which helps improve the performance stability of each component, extend its service life, and reduce the frequency of failures. Moreover, reliable locking ensures that the first door is fixed in position when closed, preventing accidental opening or loosening of the first door due to possible misoperation or malfunction of the lifting mechanism, effectively improving the safety of the first door when closed and ensuring the stability and reliability of the tail door during flight.

[0014] Optionally, a control assembly is also included, comprising a control host, a first limit switch, a second limit switch, a third limit switch, and a fourth limit switch; the control host is electrically connected to the first limit switch, the second limit switch, the third limit switch, the fourth limit switch, the first actuator, and the second actuator; the first limit switch is mounted on a connecting seat, and is triggered when the movable seat moves away from the end of the first door hinged to the lead screw; the second and third limit switches are respectively mounted on both ends of a locking pin, and are triggered when the locking pin is simultaneously inserted into the first and second lock holes, and triggered when the locking pin is removed from the first lock hole; the fourth limit switch is mounted between the first door and the door frame, and is triggered when the first door is fully closed.

[0015] By adopting the above technical solution, the control component can automatically monitor the operating status of the stern door. Based on the signals fed back from each limit switch, the control host precisely controls the first and second actuators, facilitating automated control of the stern door's opening, closing, and locking actions. This improves the accuracy and stability of stern door operation and reduces the risk of human error. Specifically, the first limit switch, when triggered by the movement of the moving seat along the central axis of the lead screw away from the stern door, sends a control signal to the control host to stop the first actuator, limiting the maximum displacement of the moving seat and preventing excessive movement. The second and third limit switches monitor the position of the locking pin and, in conjunction with the fourth limit switch and the second actuator, automatically lock the stern door after it closes and unlock it upon receiving a signal from the control host to open the door.

[0016] Optionally, the locking pin has a tapered end for inserting into the first or second lock hole; a buffer assembly for connecting the first locking lug and the door frame is provided, the buffer assembly including a piston cylinder, a piston rod, a hydraulic oil tank, a connecting pipe, and a control valve; the closed end of the piston cylinder is rotatably connected to the door frame, and the open end extends towards the direction of the first hatch, the rotation axis of the piston cylinder is parallel to the central axis of the first or second lock hole; one end of the piston rod is inserted into the open end of the piston cylinder and is slidably and sealingly connected to the inner wall of the piston cylinder to form a buffer cavity between the piston rod and the piston cylinder, and the other end is connected to the second locking lug, the sliding direction of the piston rod is inclined to the sliding direction of the locking pin; the hydraulic oil tank is set on the door frame and communicates with the buffer cavity through the connecting pipe, the buffer cavity, the connecting pipe, and the hydraulic oil tank are all filled with hydraulic oil; the control valve is electrically connected to the control host and is used to control the opening and closing of the connecting pipe.

[0017] By adopting the above technical solution, when the first door bends due to long-term use, causing a coaxiality deviation between the first and second locking holes, the tapered design of the locking pin's front end and the buffer assembly work together. During the insertion of the locking pin into the first locking hole, it guides the first locking lug to move in a plane perpendicular to the central axis of the second locking hole, automatically making the first and second locking holes coaxial and eliminating their coaxiality error. Simultaneously, when the second limit switch detects that the locking pin is fully inserted into the first and second locking holes and locks the first door to the door frame, the main control unit closes the control valve, keeping the hydraulic oil in the buffer chamber under pressure. Therefore, when the first door vibrates due to external factors, causing relative displacement between the second and first locking lugs, the buffer assembly provides cushioning between the first locking lug and the door frame, reducing the shear force exerted by the first and second locking lugs on the locking pin, preventing bending damage to the locking pin, effectively improving the service life of the locking pin, first locking lug, second locking lug, and other components, enhancing the overall stability and reliability of the tail door structure, reducing maintenance costs and frequency, and ensuring the normal operation of the aircraft's tail door.

[0018] Optionally, a pull rod assembly is also included, comprising a limiting seat, a pull rod, and a limiting pin; the limiting seat is fixed to the door frame, and a second through hole is provided on the limiting seat; the limiting pin is detachably connected to the limiting seat and passes through the second through hole; one end of the pull rod is hinged to the first hatch, and the other end extends upward through the second through hole, causing the pull rod to slide within the second through hole during the opening of the first hatch; the pull rod has a sliding groove along its length that passes through both sides and allows the limiting pin to slide through; when the limiting pin is installed on the limiting seat and the first hatch is opened to be parallel to the bottom surface of the stern compartment, the limiting pin abuts against the inner wall of the end of the sliding groove away from the first hatch.

[0019] By adopting the above technical solution, when unloading cargo, the use of the tie rod assembly can make the first hatch and the bottom of the stern hold parallel. This not only facilitates the unloading of some large cargoes, but also transfers the weight of the first hatch, which was originally borne by the lifting mechanism, to the tie rod assembly. This relieves the lifting mechanism of its load-bearing capacity on the first hatch, extends the service life of the lifting mechanism, and reduces the frequency of failures.

[0020] Optionally, a buffer is provided between the door frame and the first hatch to buffer the collision between them.

[0021] By adopting the above technical solution, the buffer can reduce the impact force generated by the collision between the first door and the door frame when the first door is closed or during flight, thereby reducing the risk of damage to the first door and door frame caused by the collision.

[0022] As another aspect of this application, a control method for the tail door of a cargo drone's cargo hold is provided, comprising the following steps: S1. The tailgate is open; Step S1 includes: S11. Control the opening mechanism to drive the two second doors to rotate outwards from their respective hinge points with the door frame, so that the two second doors move away from each other and open the tail compartment opening near the tail of the aircraft. S12. Control the first actuator to drive the nut to rotate forward, so that the moving seat slides relative to the screw along the rotation axis of the screw, and the moving seat and the first hatch move away from each other; the first hatch flips down under its own weight, driving the moving seat to move closer to the connecting seat and opening the tail hatch opening near the nose of the engine. S13. When the movable seat moves away from the connecting seat along the rotation axis of the lead screw, the first actuator is stopped. S2, tailgate closed; Step S2 includes: S21. Control the first actuator to drive the nut to reverse, so that the moving seat slides relative to the screw along the rotation axis of the screw, and the moving seat and the first hatch move closer to each other; the first hatch moves the moving seat closer to the connecting seat to a predetermined distance under its own weight, and then flips itself upward to close the part of the tail hatch opening near the nose of the aircraft. S22. Control the opening mechanism to drive the two second doors to rotate around their respective hinge points with the door frame toward the inside of the tail compartment, so that the two second doors move closer to each other and then close the remaining part of the tail compartment opening near the tail of the aircraft.

[0023] By adopting the above technical solutions, the opening and closing of the tail hatch can be controlled in an orderly manner, improving the stability of the tail hatch operation and reducing the damage to the tail hatch itself or the fuselage when the tail hatch is opened.

[0024] As another aspect of this application, an aircraft is provided, including a tail hatch as described above.

[0025] By adopting the above technical solutions, the tail hatch of the aircraft has a reasonable structural design. The coordinated opening of the first and second hatches can effectively improve cargo loading and unloading efficiency. At the same time, it can prevent the first actuator from being continuously driven when the first hatch is in contact with the ground or restricted to its maximum opening angle by external objects, which could lead to overload damage or damage to the hatch and fuselage. This improves the stability of the tail hatch operation and thus ensures the safety and convenience of the aircraft during cargo transportation.

[0026] In summary, this application includes the following beneficial technical effects: 1. This design improves the stability of the tail hatch operation and reduces damage to the tail hatch itself or the fuselage when it is opened. Specifically, when opening the tail hatch, the first actuator drives the nut to rotate forward, causing the moving seat to slide relative to the lead screw along the rotation axis, thus moving the moving seat away from the first hatch. During this process, the first hatch flips downward under its own weight, causing the moving seat to move closer to the connecting seat until the moving seat is restricted by the limiting connector, fixing the position of the moving seat relative to the tail hatch. The first hatch then moves the lead screw towards the ground, opening the tail hatch opening towards the nose of the fuselage. When the first hatch touches the ground or is restricted to its maximum opening angle by an external object, and the first actuator continues to drive the nut to rotate forward, the lead screw is relatively fixed relative to the tail hatch. The moving seat can then move along the central axis of the lead screw away from the first hatch and the moving seat on the inner wall of the tail hatch under the action of the nut, thus preventing overload of the first actuator or continuous driving of the first hatch to open, which could cause damage to the first hatch or the fuselage. Then, the opening mechanism is controlled to drive the two second hatches to rotate outwards from their respective hinge points with the door frame, moving them away from each other and opening the remaining area of ​​the tail section. When closing the hatches, the first actuator is first controlled to reverse the nut, causing the moving seat to slide relative to the screw along the rotation axis, bringing the moving seat and the first hatch closer together. During this process, the first hatch, under its own weight, moves the moving seat closer to the connecting seat until the moving seat is restricted by the limiting connector, fixing the position of the moving seat and the tail section. The first hatch, along with the screw, moves away from the ground, closing the area of ​​the tail section opening near the nose. Then, the opening mechanism is controlled to drive the two second hatches to rotate inwards from their respective hinge points with the door frame, moving them closer together and closing the remaining area of ​​the tail section opening near the tail section. 2. During the opening and closing of the first hatch, the lead screw will deviate or rotate in multiple directions. The spherical plain bearing can, to a certain extent, limit the relative position of the lead screw and the connecting seat while avoiding restricting the deviation or rotation of the lead screw, thus ensuring the flexibility of the lead screw during movement and making the opening and closing of the first hatch smoother. This also prevents damage to the lifting mechanism caused by excessive restriction of the lead screw's degrees of freedom. Furthermore, when the moving seat approaches the connecting seat to a predetermined distance, the outer ring of the spherical plain bearing can abut against the boss to limit the movement of the moving seat along the central axis of the lead screw towards the first hatch; when the moving seat moves away from the connecting seat, the spherical plain bearing can slide within the first through hole. 3. When the first hatch bends due to long-term use, causing a coaxiality deviation between the first and second locking holes, the tapered design at the front end of the locking pin and the buffer assembly work together to guide the first locking lug to move in a plane perpendicular to the central axis of the second locking hole during the insertion of the locking pin into the first locking hole, automatically making the first and second locking holes coaxial and eliminating the coaxiality error. Simultaneously, when the second limit switch detects that the locking pin is fully inserted into the first and second locking holes and locks the first hatch to the door frame, the main control unit closes the control valve, keeping the hydraulic oil in the buffer chamber under pressure. This allows the buffer assembly to provide cushioning between the first locking lug and the door frame when the first hatch vibrates due to external factors, causing relative displacement between the second and first locking lugs. This reduces the shear force exerted by the first and second locking lugs on the locking pin, preventing bending damage to the locking pin. This effectively improves the service life of the locking pin, first locking lug, second locking lug, and other components, enhances the overall stability and reliability of the tail hatch structure, reduces maintenance costs and frequency, and ensures the normal operation of the aircraft's tail hatch. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application.

[0028] Figure 2 yes Figure 1 A magnified view of part A in the middle.

[0029] Figure 3 This mainly showcases the lifting mechanism of Embodiment 1 of this application.

[0030] Figure 4 This mainly showcases the tie rod assembly of Embodiment 1 of this application.

[0031] Figure 5 This is a flowchart illustrating the opening process of the tailgate in Embodiment 1 of this application.

[0032] Figure 6 This is a flowchart illustrating the tailgate closing process of Embodiment 1 of this application.

[0033] Figure 7 This mainly showcases the buffer component of Embodiment 2 of this application.

[0034] Explanation of reference numerals in the attached drawings: 100, stern compartment; 101, stern compartment opening; 1, door frame; 2, first hatch; 3, second hatch; 4, lifting mechanism; 41, connecting seat; 411, first through hole; 42, lead screw; 43, nut; 44, ball bearing; 45, movable seat; 46, first actuator; 47, limiting connector; 471, spherical bearing; 5, splitting mechanism; 51, rotating rod; 52, connecting rod; 53, driving component; 6, locking mechanism; 61, first locking lug; 611, first lock hole; 62, second locking lug; 621. Second locking hole; 63. Slide rod; 64. Locking pin; 65. Second actuator; 7. Control assembly; 71. Control host; 72. First limit switch; 73. Second limit switch; 74. Third limit switch; 75. Fourth limit switch; 8. Buffer assembly; 81. Piston cylinder; 82. Piston rod; 83. Hydraulic oil tank; 84. Connecting pipe; 85. Control valve; 86. Buffer chamber; 9. Pull rod assembly; 91. Limit seat; 911. Second through hole; 92. Pull rod; 921. Slide groove; 93. Limit pin. Detailed Implementation

[0035] The following combination Figures 1-7 This application will be described in further detail.

[0036] This application discloses a cargo hold tail door actuation system and control method for a cargo drone.

[0037] Example 1

[0038] Reference Figure 1 and Figure 2 The cargo drone's cargo hold tail door actuation system includes a door frame 1, a first door 2, at least two second doors 3, a lifting mechanism 4, a splitting mechanism 5, a locking mechanism 6, a control assembly 7, and a lever assembly 9. Specifically, the door frame 1 is generally rectangular and is fixedly installed around the bottom opening of the tail hold 100. The first door 2 is generally rectangular and is hinged on one side to the door frame 1 near the nose of the drone, used to cover a portion of the tail hold opening 101 near the nose of the drone.

[0039] The two second doors 3 are in a doubly open state and are respectively hinged to the two sides of the door frame 1 in the area of ​​the tail hatch opening 101 that is not covered by the first door 2, and are used to cover the remaining area of ​​the tail hatch opening 101 near the tail that is not covered by the first door 2.

[0040] Reference Figure 2 and Figure 3In this embodiment, lifting mechanisms 4 are provided on both sides of the first hatch 2, respectively, for raising or lowering the two sides of the first hatch 2 to control the opening or closing of the first hatch 2 as a whole. The lifting mechanism 4 includes a connecting seat 41, a lead screw 42, a nut 43, multiple balls 44, a moving seat 45, a first actuator 46, and a limiting connector 47. The connecting seat 41 is fixed to the door frame 1 by bolts. The connecting seat 41 has a first through hole 411 that penetrates its upper and lower surfaces. One end of the lead screw 42 is hinged to the first hatch 2, and the other end extends upward after passing through the first through hole 411. The nut 43 is set on the lead screw 42, and multiple balls 44 are set between the nut 43 and the lead screw 42 to cooperate with the lead screw 42 and the nut 43 to form a ball screw 42 pair. It should be emphasized that the ball screw is a mature existing technology, and its specific connection method will not be described in detail here.

[0041] The movable seat 45 is located outside the nut 43 and is rotatably connected to the nut 43. The movable seat 45 is located on the side of the connecting seat 41 away from the end of the lead screw 42 that is hinged to the first hatch 2. The outer wall of the movable seat 45 slides against the inner wall of the tail compartment 100. The first actuator 46 can be specifically regarded as a combination of a servo motor and a gearbox. The first actuator 46 is mounted on the movable seat 45 to drive the nut 43 to rotate.

[0042] A limiting connector 47 is disposed on the movable seat 45. The limiting connector 47 can restrict the movable seat 45 from moving towards the first hatch 2 along the central axis of the lead screw 42 when the movable seat 45 moves closer to the connecting seat 41 to a predetermined distance. The limiting connector 47 includes a spherical bearing 471. The inner ring of the spherical bearing 471 is fixedly sleeved on the movable seat 45, and the outer ring of the spherical bearing 471 is coaxially slidably disposed in the first through hole 411. The spherical bearing 471, the first through hole 411, and the central axis of the lead screw 42 are coaxially disposed. A boss is provided in the first through hole 411 for abutting against the side of the outer ring of the spherical bearing 471 near the first hatch 2. The boss is a ring of raised structure of the connecting seat 41 in the first through hole 411, used to limit the maximum limit position of the movement of the spherical bearing 471 and the movable seat 45 towards the first hatch 2 along the central axis of the lead screw 42.

[0043] Reference Figure 1The opening mechanism 5 is used to drive the two second hatches 3 to open away from each other or close together. The opening mechanism 5 includes a rotating rod 51, at least two connecting rods 52, and a driving component 53. The rotating rod 51 is rotatably connected to the inner wall of the stern compartment 100. The first ends of the two connecting rods 52 are rotatably connected to the surfaces of the two second hatches 3 near the inner cavity of the stern compartment 100 via universal joints, and the second ends of the two connecting rods 52 are rotatably connected to the two ends of the rotating rod 51 via universal joints. The driving component 53 can be a servo motor. The driving component 53 is mounted on the inner wall of the stern compartment 100 to drive the rotating rod 51 to rotate, thereby causing the second ends of the two connecting rods 52 to move closer or further apart.

[0044] This improves the stability of the tail hatch operation and reduces damage to the tail hatch itself or the fuselage when it is opened. Specifically, when opening the tail hatch, the split-opening mechanism 5 is first controlled to drive the two second hatches 3 to rotate outwards from their respective hinge points with the door frame 1, so that the two second hatches 3 move away from each other and open the tail hatch opening 101 near the tail. Then, the first actuator 46 is controlled to drive the nut 43 to rotate clockwise, so that the moving seat 45 slides relative to the lead screw 42 along the rotation axis of the lead screw 42, and moves the moving seat 45 away from the first hatch 2.

[0045] During the process, the first hatch 2 flips downward under its own weight, which in turn drives the movable seat 45 to move closer to the connecting seat 41 until the outer ring of the spherical bearing 471 abuts against the boss, restricting the movable seat 45 from moving further (due to the presence of the spherical bearing 471, the movable seat 45 will still have a certain angle of offset or rotation relative to the connecting seat 41). The first hatch 2 drives the lead screw 42 to move closer to the ground and open the tail hatch opening 101 near the engine head (equivalent to the ball screw drive, where the lead screw 42 is restricted to moving along its own central axis but cannot rotate around its own central axis, while the nut 43 is restricted to rotating around its own central axis but cannot move along its own central axis).

[0046] When the first hatch 2 is in contact with the ground or restricted to its maximum opening angle by an external object, and the first actuator 46 continuously drives the nut 43 to rotate forward, the position of the lead screw 42 relative to the tail compartment 100 is relatively fixed. The movable seat 45 can move along the central axis of the lead screw 42 away from the first hatch 2 and the movable seat 45 on the inner wall of the tail compartment 100 under the drive of the nut 43 (equivalent to the ball screw drive, where the lead screw 42 is restricted from moving along its own central axis and rotating around its own central axis, while the nut 43 is restricted from rotating around its own central axis and moving along its own central axis), thereby preventing the first actuator 46 from being overloaded or continuously driving the first hatch 2 to open, which would cause damage to the first hatch 2 or the fuselage.

[0047] The closing procedure is the reverse. First, the first actuator 46 drives the nut 43 to reverse, causing the movable seat 45 to slide relative to the lead screw 42 along the rotation axis of the lead screw 42, bringing the movable seat 45 closer to the first hatch 2. During this process, the first hatch 2, under its own weight, moves the movable seat 45 closer to the connecting seat 41 until the movable seat 45 is restricted from moving by the limiting connector 47, fixing the position of the movable seat 45 relative to the tail compartment 100. After the first hatch 2 and the lead screw 42 move away from the ground together, the portion of the tail compartment opening 101 near the nose closes. Then, the splitting mechanism 5 drives the two second hatches 3 to rotate around their respective hinge points with the door frame 1 towards the inside of the tail compartment 100, bringing the two second hatches 3 closer to each other and closing the portion of the tail compartment opening 101 near the tail.

[0048] During the opening and closing of the first hatch 2, the lead screw 42 will deflect or rotate in multiple directions. The joint bearing 471 can limit the relative position of the lead screw 42 and the connecting seat 41 to a certain extent, while avoiding limiting the deflection or rotation of the lead screw 42, so as to ensure the flexibility of the lead screw 42 during the movement, making the first hatch 2 open and close more smoothly, and avoiding excessive restriction of the degree of freedom of the lead screw 42, which could damage the lifting mechanism 4.

[0049] Preferably, a buffer is provided between the door frame 1 and the first door 2 to buffer their collision. The buffer is fixedly installed on the door frame 1, and the buffer can be a hydraulic buffer. This reduces the impact force generated by the collision between the first door 2 and the door frame 1 when the first door 2 is closed or during flight, and reduces the risk of damage to the first door 2 and the door frame 1 due to the collision.

[0050] Reference Figure 1 and Figure 2 In this embodiment, a locking mechanism 6 is also provided on each side of the first hatch 2, for locking the first hatch 2 and the door frame 1 respectively. The locking mechanism 6 includes a first locking lug 61, a second locking lug 62, a slide bar 63, a locking pin 64, and a second actuator 65. The first locking lug 61 is welded and fixed to the door frame 1, and a first lock hole 611 is provided on the first locking lug 61 for the locking pin 64 to be inserted and engaged. The second locking lug 62 is welded and fixed to the first hatch 2, and a second lock hole 621 is provided on the second locking lug 62 for the locking pin 64 to be inserted and engaged.

[0051] The slide rod 63 is slidably mounted on the first hatch 2 along a direction parallel to the central axis of the second lock hole 621. The locking pin 64 is fixedly mounted on the slide rod 63. The second actuator 65 can be regarded as a combination of a hydraulic cylinder and a connecting rod 52 mechanism. The second actuator 65 is mounted on the first hatch 2 to drive the slide rod 63 to slide. When the first hatch 2 is in the fully closed state, the first lock hole 611 and the second lock hole 621 are coaxial. After the slide rod 63 slides, it can drive the locking pin 64 to simultaneously insert into the first lock hole 611 and the second lock hole 621 or move out of the first lock hole 611.

[0052] Thus, after the first hatch 2 is closed by the lifting mechanism 4, the second actuator 65 is first controlled to drive the slide bar 63 to slide, causing the locking pin 64 to simultaneously insert into the first lock hole 611 and the second lock hole 621. Then, the first actuator 46 is controlled to drive the nut 43 to rotate clockwise, causing the moving seat 45 to slide relative to the lead screw 42 along the rotation axis of the lead screw 42, and causing the moving seat 45 to move away from the first hatch 2. At this time, because the locking pin 64 restricts the opening of the first hatch 2, the position of the lead screw 42 relative to the tail compartment 100 is relatively fixed. After the nut 43 rotates clockwise, the moving seat 45 can move along the central axis of the lead screw 42 away from the first hatch 2 and the moving seat 45 on the inner wall of the tail compartment 100 under the drive of the nut 43 (equivalent to in ball screw transmission, the lead screw 42 is restricted from moving along its own central axis and rotating around its own central axis, while the nut 43 is restricted from rotating around its own central axis and moving along its own central axis). This design, through the locking mechanism 6, transfers the weight of the first cabin door 2, originally borne by the lifting mechanism 4, to the locking mechanism 6. This relieves the lifting mechanism 4 of its load-bearing capacity on the first cabin door 2, extending its service life and reducing the frequency of malfunctions. Simultaneously, it prevents the first cabin door 2 from accidentally opening or loosening due to potential misoperation or malfunction of the lifting mechanism 4, improving the safety of the first cabin door 2 when closed and ensuring the stability and reliability of the tail cabin door during flight.

[0053] Reference Figure 1 and Figure 2In this embodiment, the control group includes a control host 71, a first limit switch 72, a second limit switch 73, a third limit switch 74, and a fourth limit switch 75. The control host 71 is specifically a microcomputer with control software installed internally. The control host 71 is mounted on the outer wall of the stern compartment 100 and is electrically connected to the first limit switch 72, the second limit switch 73, the third limit switch 74, the fourth limit switch 75, the first actuator 46, and the second actuator 65. The first limit switch 72 is fixedly mounted on the connecting seat 41. The first limit switch 72 is triggered when the moving seat 45 moves a certain distance away from the end of the first hatch 2 hinged to the lead screw 42. The second limit switch 73 and the third limit switch 74 are respectively fixedly mounted on the first hatch 2 at both ends of the locking pin 64. The second limit switch 73 is triggered when the locking pin 64 is fully inserted into both the first lock hole 611 and the second lock hole 621 simultaneously. The third limit switch 74 is triggered when the locking pin 64 is fully removed from the first lock hole 611. The fourth limit switch 75 is fixedly installed on the door frame 1 and located between the first hatch 2 and the door frame 1. When the first hatch 2 is completely closed, the fourth limit switch 75 can be triggered.

[0054] In this way, the control component 7 can automatically monitor the operating status of the stern door and control the opening and closing of the entire stern door with one button. The control host 71, based on the signals fed back from each limit switch, precisely controls the first actuator 46 and the second actuator 65, facilitating automated control of the stern door's opening, closing, and locking actions, improving the accuracy and stability of stern door operation, and reducing the risk of human error. Specifically, the first limit switch 72, when triggered when the moving seat 45 moves away from the first stern door 2 along the central axis of the lead screw 42, sends a control signal to the control host 71, stopping the first actuator 46 to limit the maximum displacement of the moving seat 45 and prevent excessive movement. The second limit switch 73 and the third limit switch 74 can monitor the position of the locking pin 64 and, in conjunction with the fourth limit switch 75 and the second actuator 65, automatically lock the first stern door 2 after it closes, and unlock it upon receiving a signal from the control host 71 to open the door.

[0055] In other embodiments, to further ensure the coaxiality of the first locking hole 611 and the second locking hole 621 after the first hatch 2 is closed, a guide groove can be provided on the first locking lug 61, and a guide pin can be added to the second locking lug 62 to abut against the guide groove. During the closing process of the first hatch 2, the guide groove can accurately guide the guide pin into the guide groove for abutment, and after the guide pin and the guide groove abut against each other, the first locking hole 611 and the second locking hole 621 can be coaxial. In addition, after the two second hatches 3 are closed, the two second hatches 3 can also be locked together by a locking mechanism 6. Specifically, the first locking lug 61 and the second locking lug 62 can be installed on the two second hatches 3 respectively, and the first locking hole 611 and the second locking hole 621 can be ensured to be coaxial when the two second hatches 3 are fully closed. Furthermore, some limit switches can also be added to monitor the opening and closing status of the two second hatches 3 and the position status of the locking pin 64.

[0056] Reference Figure 2 and Figure 4 In this embodiment, the pull rod assembly 9 includes a limiting seat 91, a pull rod 92, and a limiting pin 93. The limiting seat 91 is fixedly installed on the door frame 1 by bolts, and the limiting seat 91 has a second through hole 911 that passes through its upper and lower surfaces. The limiting pin 93 is detachably connected to the limiting seat 91 and passes through the second through hole 911 perpendicular to its central axis. One end of the pull rod 92 is hinged to the first hatch 2, and the other end extends upward through the second through hole 911. During the opening of the first hatch 2, the pull rod 92 can slide within the second through hole 911. The pull rod 92 has a groove 921 along its length that passes through both sides and allows the limiting pin 93 to slide through.

[0057] When the limit pin 93 is installed on the limit seat 91 and the first hatch 2 is opened to be parallel to the bottom surface of the stern compartment 100, the limit pin 93 abuts against the inner wall of the end of the slide groove 921 away from the first hatch 2.

[0058] In this way, when unloading cargo, the use of the tie rod assembly 9 can make the bottom surface of the first hatch 2 and the tail hatch 100 parallel. This not only facilitates the unloading of some large cargoes, but also transfers the weight of the first hatch 2 and the weight of the cargo, which were originally borne by the lifting mechanism 4, to the tie rod assembly 9. This relieves the lifting mechanism 4 of its load-bearing capacity on the first hatch 2, extends the service life of the lifting mechanism 4, and reduces the frequency of failures.

[0059] The implementation principle of Example 1 is as follows: (Refer to...) Figure 5When opening the tail hatch, firstly, the second actuator 65 drives the slide bar 63 to slide, causing the locking pin 64 to simultaneously exit the first locking hole 611. When the locking pin 64 triggers the third limit switch 74, the first hatch 2 is successfully unlocked. Then, the first actuator 46 drives the nut 43 to rotate forward, causing the moving seat 45 to slide relative to the lead screw 42 along the rotation axis of the lead screw 42, and causing the moving seat 45 and the first hatch 2 to move away from each other. During this process, the first hatch 2 flips downward under its own weight, thereby causing the moving seat 45 to move closer to the connecting seat 41 until the outer ring of the spherical bearing 471 abuts against the boss, restricting the moving seat 45 from moving further. The first hatch 2 drives the lead screw 42 to move closer to the ground together and open the part of the tail hatch opening 101 near the nose of the aircraft. When the first hatch 2 is in contact with the ground or its maximum opening angle is limited by external objects, and the first actuator 46 continuously drives the nut 43 to rotate forward, the position of the lead screw 42 relative to the tail compartment 100 is relatively fixed. The movable seat 45, driven by the nut 43, can move along the central axis of the lead screw 42 away from the first hatch 2 and the movable seat 45 on the inner wall of the tail compartment 100, thereby preventing the first actuator 46 from being overloaded or from continuously driving the first hatch 2 to open, which could cause damage to the first hatch 2 or the fuselage. When the movable seat 45 triggers the first limit switch 72 while moving along the central axis of the lead screw 42 away from the first hatch 2, the first limit switch 72 sends a control signal to the control host 71 to stop the first actuator 46, thus limiting the maximum displacement of the movable seat 45 and preventing excessive movement.

[0060] Finally, the control mechanism 5 drives the two second doors 3 to rotate outwards from their respective hinge points with the door frame 1 towards the tail compartment 100, so that the two second doors 3 move away from each other and open the tail compartment opening 101 to the remaining part near the tail of the aircraft.

[0061] Reference Figure 6 When closing the hatch, the first actuator 46 drives the nut 43 to reverse, causing the movable seat 45 to slide relative to the lead screw 42 along the rotation axis of the lead screw 42, and bringing the movable seat 45 closer to the first hatch 2. During this process, the first hatch 2, under its own weight, moves the movable seat 45 closer to the connecting seat 41 until the movable seat 45 is restricted from moving by the limiting connector 47, so that the position of the movable seat 45 and the tail compartment 100 is relatively fixed. The first hatch 2 moves the lead screw 42 away from the ground together. When the fourth limit switch 75 is triggered by the first hatch 2, the fourth limit switch 75 will send a control signal to the control host 71 to stop the first actuator 46. At this time, the first hatch 2 completely closes the part of the tail compartment opening 101 near the nose.

[0062] Subsequently, the second actuator 65 continues to drive the slide bar 63 to slide, causing the locking pin 64 to simultaneously insert into the first locking hole 611 and the second locking hole 621. When the locking pin 64 triggers the second limit switch 73, the first hatch 2 is successfully locked. The first actuator 46 is then controlled to drive the nut 43 to rotate clockwise, causing the moving seat 45 to slide relative to the lead screw 42 along the rotation axis of the lead screw 42, and moving the moving seat 45 away from the first hatch 2. This transfers the weight of the first hatch 2, originally borne by the lifting mechanism 4, to the locking mechanism 6, relieving the lifting mechanism 4 of its load-bearing capacity on the first hatch 2. When the moving seat 45 triggers the first limit switch 72 during movement, the first limit switch 72 sends a control signal to the control host 71, stopping the first actuator 46 to limit the maximum displacement of the moving seat 45 and prevent excessive movement.

[0063] Finally, the control mechanism 5 drives the two second doors 3 to rotate inwards around their respective hinge points with the door frame 1 towards the tail compartment 100, so that the two second doors 3 move closer to each other and close the tail compartment opening 101 near the tail of the aircraft. In addition, during the opening and closing of the first door 2, the lead screw 42 will deviate or rotate in multiple directions. The spherical bearing 471 can limit the relative position of the lead screw 42 and the connecting seat 41 to a certain extent, while avoiding limiting the deviance or rotation of the lead screw 42, so as to ensure the flexibility of the lead screw 42 during movement, making the first door 2 open and close more smoothly, and avoiding damage to the lifting mechanism 4 due to excessive restriction of the degree of freedom of the lead screw 42.

[0064] Example 2

[0065] Reference Figure 7 The main difference between this embodiment 2 and embodiment 1 is that the end of the locking pin 64 used to insert into the first lock hole 611 or the second lock hole 621 is tapered; a buffer assembly 8 for connecting the first locking ear 61 and the door frame 1 is provided.

[0066] Specifically, the buffer assembly 8 includes a piston cylinder 81, a piston rod 82, a hydraulic oil tank 83, a connecting pipe 84, and a control valve 85. The piston cylinder 81 is a cylinder that is closed at one end and open at the other. The closed end of the piston cylinder 81 is rotatably connected to the door frame 1 via a hinge, and the open end extends toward the first hatch 2. The rotation axis of the piston cylinder 81 is parallel to the central axis of the first lock hole 611 or the second lock hole 621.

[0067] The first end of the piston rod 82 is inserted into the open end of the piston cylinder 81 and is slidably connected to the inner wall of the piston cylinder 81 to form a buffer cavity 86 between the piston rod 82 and the piston cylinder 81; the sliding direction of the piston rod 82 is perpendicular to the sliding direction of the locking pin 64. The first locking lug 61 is welded and fixed to the second end of the piston rod 82. When the piston rod 82 slides in the piston cylinder 81, it can drive the first locking lug 61 to move in a plane perpendicular to the central axis of the second lock hole 621. The hydraulic oil tank 83 is fixedly installed on the door frame 1 and is connected to the buffer cavity 86 through the connecting pipe 84; the control valve 85 is connected to the connecting pipe 84 and is electrically connected to the control host 71 to control the opening and closing of the connecting pipe 84.

[0068] Thus, when the first hatch 2 slightly bends due to long-term use, causing a small coaxiality deviation between the first locking hole 611 and the second locking hole 621, the tapered design at the front end of the locking pin 64 and the buffer assembly 8 work together to guide the first locking lug 61 to move in a plane perpendicular to the central axis of the second locking hole 621 during the insertion of the locking pin 64 into the first locking hole 611, making the first locking hole 611 and the second locking hole 621 automatically coaxial and eliminating the coaxiality error between them. At the same time, when the second limit switch 73 detects that the locking pin 64 is fully inserted into the first locking hole 611 and the second locking hole 621 and locks the first hatch 2 and the door frame 1, the control host 71 controls the control valve 85 to close, keeping the hydraulic oil in the buffer chamber 86 in a pressure-holding state. When the first hatch 2 vibrates due to external factors, causing relative displacement between the second locking ear 62 and the first locking ear 61, the buffer assembly 8 can provide buffer between the first locking ear 61 and the door frame 1, reducing the shearing force of the first locking ear 61 and the second locking ear 62 on the locking pin 64, preventing the locking pin 64 from bending and being damaged, effectively improving the service life of various components such as the locking pin 64, the first locking ear 61, and the second locking ear 62, and enhancing the stability and reliability of the overall structure of the tail hatch.

[0069] It should be emphasized that, in order to ensure that the locking pin 64 is inserted into the first locking hole 611 each time and guides the first locking ear 61 to move, the design of the buffer assembly 8 needs to limit the rotation angle range of the piston cylinder 81 and the extension stroke of the piston rod 82, so as to ensure that no matter how the first locking ear 61 moves, the central axis of the first locking hole 611 is within the circumference of the second locking hole 621.

[0070] The implementation principle of Embodiment 2 is as follows: By adding a buffer assembly 8 to connect the door frame 1 and the first locking lug 61, when the first lock hole 611 and the second lock hole 621 become misaligned due to bending after long-term use of the first hatch 2, the locking pin 64 guides the first locking lug 61 to move and automatically eliminate the coaxiality error between the first lock hole 611 and the second lock hole 621. Furthermore, the buffer assembly 8 provides a buffer between the first locking lug 61 and the door frame 1, reducing the shear force exerted by the first locking lug 61 and the second locking lug 62 on the locking pin 64, preventing the locking pin 64 from bending and being damaged, thereby enhancing the overall stability and reliability of the stern hatch structure.

[0071] Example 3

[0072] A method for controlling the tail door of a cargo drone's cargo hold includes the following steps:

[0073] S1, the tailgate is open.

[0074] Step S1 includes:

[0075] S11, control the opening mechanism 5 to drive the two second doors 3 to rotate outwards from their respective hinge points with the door frame 1 towards the tail compartment 100, so that the two second doors 3 move away from each other and open the tail compartment opening 101 near the tail of the aircraft.

[0076] S12. Control the first actuator 46 to drive the nut 43 to rotate forward, so that the moving seat 45 slides relative to the lead screw 42 along the rotation axis of the lead screw 42, and moves the moving seat 45 away from the first hatch 2. Under its own weight, the first hatch 2 flips downward and drives the moving seat 45 to approach the connecting seat 41 and open the tail hatch opening 101 near the nose of the engine.

[0077] S13. When the moving seat 45 moves away from the connecting seat 41 along the rotation axis of the lead screw 42, the first actuator 46 is stopped.

[0078] S2, tailgate closed.

[0079] Step S2 includes:

[0080] S21. Control the first actuator 46 to drive the nut 43 to reverse, so that the moving seat 45 slides relative to the lead screw 42 along the rotation axis of the lead screw 42, and the moving seat 45 and the first hatch 2 move closer to each other; under the action of its own weight, the first hatch 2 drives the moving seat 45 to move closer to the connecting seat 41 to a predetermined distance and then flips itself upward to close the part of the tail hatch opening 101 near the nose of the aircraft.

[0081] S22, control the opening mechanism 5 to drive the two second doors 3 to rotate around their respective hinge points with the door frame 1 toward the inside of the tail compartment 100, so that the two second doors 3 come closer to each other and close the remaining part of the tail compartment opening 101 near the tail of the aircraft.

[0082] The implementation principle of Example 3 is as follows: by orderly controlling the opening and closing of the tail hatch, the stability of the tail hatch operation is improved, and the damage to the tail hatch itself or the fuselage when the tail hatch is opened is reduced.

[0083] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A cargo hold tail door actuation system for a cargo drone, characterized in that, include: Door frame (1) is set around the tail hatch opening (101); The first hatch (2) is hinged to one end of the door frame (1) near the nose and is used to close a portion of the tail hatch opening (101); At least two second hatches (3), which are hinged to the two sides of the door frame (1) in a doubly open state, for closing the remaining area of ​​the tail hatch opening (101); The lifting mechanism (4) includes a connecting seat (41), a lead screw (42), a nut (43), multiple balls (44), a movable seat (45), a first actuator (46), and a limiting connector (47). The connecting seat (41) is fixed to the door frame (1), and a first through hole (411) is provided on the connecting seat (41). One end of the lead screw (42) is hinged to the first hatch (2), and the other end extends upward through the first through hole (411). The nut (43) is provided on the lead screw (42), and multiple balls (44) are provided between the nut (43) and the lead screw (42) to cooperate with the lead screw (42) and the first hatch (2). Nut (43) forms a ball screw pair; the movable seat (45) is located on the side of the connecting seat (41) away from the end of the screw (42) that is hinged to the first hatch (2), and the movable seat (45) slides against the inner wall of the tail compartment (100); the movable seat (45) is rotatably connected to the nut (43), and the first actuator (46) is used to drive the nut (43) to rotate; the limiting connector (47) is located on the movable seat (45), and the limiting connector (47) can restrict the movable seat (45) from moving towards the first hatch (2) along the central axis of the screw (42) when the movable seat (45) moves towards the connecting seat (41) to a predetermined distance; The opening mechanism (5) is used to drive the two second doors (3) to open away from each other or close together.

2. The cargo hold tail door actuation system for a cargo drone according to claim 1, characterized in that: The limiting connector (47) includes a spherical bearing (471), the inner ring of which is fixedly connected to the movable seat (45), and the outer ring of which is coaxially slidably disposed in the first through hole (411). The first through hole (411) is provided with a boss for abutting against the side of the outer ring of the spherical bearing (471) near the first hatch (2).

3. The cargo hold tail door actuation system for a cargo drone according to claim 1, characterized in that: The splitting mechanism (5) includes a rotating rod (51), at least two connecting rods (52), and a driving member (53). The rotating rod (51) is rotatably connected to the inner wall of the stern compartment (100). The first ends of the two connecting rods (52) are rotatably connected to the two second doors (3), and the second ends of the two connecting rods (52) are rotatably connected to the two ends of the rotating rod (51). The driving member (53) is used to drive the rotating rod (51) to rotate, so as to drive the second ends of the two connecting rods (52) to move closer or further apart.

4. The cargo hold tail door actuation system for a cargo drone according to claim 1, characterized in that: It also includes a locking mechanism (6), which includes a first locking lug (61), a second locking lug (62), a slide bar (63), a locking pin (64), and a second actuator (65); the first locking lug (61) is disposed on the door frame (1), and the first locking lug (61) has a first lock hole (611) for the locking pin (64) to be inserted and engaged; the second locking lug (62) is disposed on the first hatch (2), and the second locking lug (62) has a locking pin (64) for the locking pin (64) to be inserted and engaged. Insert the second locking hole (621) into the first door (2); the slide bar (63) is slidably mounted on the first door (2), the locking pin (64) is mounted on the slide bar (63), and the second actuator (65) is used to drive the slide bar (63) to slide; when the first door (2) is closed, the first locking hole (611) and the second locking hole (621) can be coaxial, and the sliding of the slide bar (63) can drive the locking pin (64) to simultaneously insert into the first locking hole (611) and the second locking hole (621) or move out of the first locking hole (611).

5. The cargo hold tail door actuation system for a cargo drone according to claim 4, characterized in that: It also includes a control assembly (7), which includes a control host (71), a first limit switch (72), a second limit switch (73), a third limit switch (74), and a fourth limit switch (75); the control host (71) is electrically connected to the first limit switch (72), the second limit switch (73), the third limit switch (74), the fourth limit switch (75), the first actuator (46), and the second actuator (65); the first limit switch (72) is mounted on a connecting seat (41), and the moving seat (45) is hinged to the first hatch (2) away from the lead screw (42). When one end moves, the first limit switch (72) can be triggered; the second limit switch (73) and the third limit switch (74) are respectively located at both ends of the locking pin (64). When the locking pin (64) is inserted into the first lock hole (611) and the second lock hole (621) at the same time, the second limit switch (73) can be triggered. After the locking pin (64) moves out of the first lock hole (611), the third limit switch (74) can be triggered. The fourth limit switch (75) is located between the first hatch (2) and the door frame (1). When the first hatch (2) is completely closed, the fourth limit switch (75) can be triggered.

6. The cargo hold tail door actuation system for a cargo drone according to claim 5, characterized in that: The locking pin (64) is tapered at one end for insertion into the first lock hole (611) or the second lock hole (621); a buffer assembly (8) for connecting the first locking lug (61) and the door frame (1) is provided, the buffer assembly (8) including a piston cylinder (81), a piston rod (82), a hydraulic oil tank (83), a connecting pipe (84), and a control valve (85); the closed end of the piston cylinder (81) is rotatably connected to the door frame (1), and the open end extends toward the direction close to the first hatch (2), the rotation axis of the piston cylinder (81) is parallel to the central axis of the first lock hole (611) or the second lock hole (621); one end of the piston rod (82) is tapered. One end is inserted into the open end of the piston cylinder (81) and is slidably connected to the inner wall of the piston cylinder (81) to form a buffer cavity (86) between the piston rod (82) and the piston cylinder (81). The other end is connected to the second locking ear (62). The sliding direction of the piston rod (82) is inclined to the sliding direction of the locking pin (64). The hydraulic oil tank (83) is set on the door frame (1) and is connected to the buffer cavity (86) through the connecting pipe (84). The buffer cavity (86), the connecting pipe (84) and the hydraulic oil tank (83) are all filled with hydraulic oil. The control valve (85) is electrically connected to the control host (71) and is used to control the opening and closing of the connecting pipe (84).

7. The cargo hold tail door actuation system for a cargo drone according to claim 1, characterized in that: It also includes a pull rod assembly (9), which includes a limiting seat (91), a pull rod (92), and a limiting pin (93); the limiting seat (91) is fixed to the door frame (1), and a second through hole (911) is provided on the limiting seat (91); the limiting pin (93) is detachably connected to the limiting seat (91) and passes through the second through hole (911); one end of the pull rod (92) is hinged to the first hatch (2), and the other end passes through the second through hole (911) and extends towards... Extending upwards, the first hatch (2) drives the pull rod (92) to slide within the second through hole (911) during the opening process; the pull rod (92) has a groove (921) that runs through both sides of itself and allows the limiting pin (93) to slide through it; when the limiting pin (93) is installed on the limiting seat (91) and the first hatch (2) is opened to be parallel to the bottom surface of the tail compartment (100), the limiting pin (93) abuts against the inner wall of the end of the groove (921) away from the first hatch (2).

8. The cargo hold tail door actuation system for a cargo drone according to claim 1, characterized in that: A buffer is provided between the door frame (1) and the first door (2) to buffer the collision between the two.

9. A control method for the cargo hold tail door actuation system of a cargo drone as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The tailgate is open; Step S1 includes: S11. Control the opening mechanism (5) to drive the two second doors (3) to rotate around their respective hinge points with the door frame (1) toward the outside of the tail compartment (100), so that the two second doors (3) move away from each other and open the tail compartment opening (101) near the tail of the aircraft. S12. Control the first actuator (46) to drive the nut (43) to rotate forward, so that the moving seat (45) slides relative to the lead screw (42) along the rotation axis of the lead screw (42), and makes the moving seat (45) and the first hatch (2) move away from each other; the first hatch (2) flips down under its own weight and drives the moving seat (45) to move closer to the connecting seat (41) and open the tail hatch opening (101) near the nose of the engine. S13. When the movable seat (45) moves away from the connecting seat (41) along the rotation axis of the lead screw (42), the first actuator (46) is stopped. S2, tailgate closed; Step S2 includes: S21. Control the first actuator (46) to drive the nut (43) to reverse, so that the moving seat (45) slides relative to the lead screw (42) along the rotation axis of the lead screw (42), and the moving seat (45) and the first hatch (2) move closer to each other; the first hatch (2) moves the moving seat (45) towards the connecting seat (41) by its own weight until it reaches a predetermined distance and then flips upward to close the part of the tail hatch opening (101) near the nose of the aircraft. S22. Control the opening mechanism (5) to drive the two second doors (3) to rotate around their respective hinge points with the door frame (1) toward the inside of the tail compartment (100), so that the two second doors (3) come closer to each other and close the tail compartment opening (101) and the remaining part near the tail.

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