Four-rotor unmanned aerial vehicle

Abstract

The four-rotor unmanned aerial vehicle comprises a vehicle body, main supporting arms are transversely and fixedly installed at the four corners of the upper portion of the vehicle body, auxiliary supporting arms are fixedly installed at the positions, located below the main supporting arms, of the four corners of the upper portion of the vehicle body, and a box is fixedly installed at the front end of each main supporting arm. By arranging the main rotor and the auxiliary rotor, main lift force is provided by the main rotor during normal flight, the auxiliary rotor is stored in the protective cover, is adsorbed and fixed with the box body through an electromagnetic chuck, does not participate in power output and reduces aerodynamic resistance, and when the main rotor is broken due to impact and fatigue or lift force is abnormal, the system quickly triggers an emergency mechanism to achieve the purpose of emergency rescue. The electromagnetic chuck is powered off to release the protective cover, the electric push rod pushes the rotary bearing outer ring to move downwards, the paddle seat is driven to descend along the thread of the shaft rod and is locked, and the auxiliary rotor enters the working position. The motor drives the shaft rod to drive the auxiliary rotor to rotate, lift loss is quickly compensated, and the fuselage is prevented from being out of control due to unbalance.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles (UAVs), and in particular to a four-rotor UAV. Background Art

[0002] When a drone's rotor strikes a tree, building, or other structure during flight, the blades experience a sudden lateral impact force that exceeds the material's flexural strength, causing cracks or breakage. Alternatively, when the blades rotate at high speeds, microcracks gradually develop at the fiber-resin interface of the rotor's carbon fiber composite material. Over extended flight periods, the risk of rotor fracture increases significantly.

[0003] When a drone's blades break due to the rotor hitting an obstacle, or microcracks appear due to long-term fatigue, and the risk of fracture increases, the flight status will gradually evolve from a minor abnormality to an uncontrolled crash as the degree of the fault develops. After the blades crack, the local structural strength decreases, and the lift generated by the blades when rotating at high speed will be lower than normal, causing the drone to tilt toward the side of the faulty blade and the fuselage to continue shaking. If the shaking effect is slight, it will affect the flight stability. If the shaking effect is severe, it will cause an uncontrolled crash.

[0004] Therefore, it is necessary to invent a four-rotor drone to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a quad-rotor drone to solve the above-mentioned deficiencies in the technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: a quad-rotor drone, comprising a body, main arms being laterally fixedly mounted at the four upper corners of the body, secondary arms being fixedly mounted at the four upper corners of the body and below each main arm, and a box being fixedly mounted at the front end of each main arm; A shaft is vertically mounted in the middle of each box, a main rotor is mounted on the top of the box, a propeller seat is movably mounted on the lower end of the shaft and located below the bottom of the box, and auxiliary rotors are fixedly mounted on both sides of the propeller seat; A rotary bearing is provided between the top of the paddle seat and the bottom of the box body. The top of the paddle seat is fixedly connected to the inner ring of the rotary bearing. Electric push rods are provided on both sides of the interior of the box body. The output end of each electric push rod passes through the bottom of the box body and is connected to the two ends of the outer ring of the rotary bearing. A protective cover is provided on the outer side of each box body. The protective cover is located below the main rotor and covers the outside of the auxiliary rotor.

[0007] As a preferred solution of the present invention, the front end of each auxiliary arm is fixedly installed with a base, and a motor is fixedly installed in each base. The bottom end of the shaft is fixedly connected to the output end of the motor, and the upper end of the shaft passes through the inner ring of the rotating bearing and is fixedly connected to the inner wall of the inner ring of the rotating bearing.

[0008] As a preferred solution of the present invention, iron sheets are fixedly installed on the inner walls on both sides of the upper end of the protective cover, and electromagnetic suction cups are fixedly installed on both sides of the front end of the box body. The output end of the electromagnetic suction cup is located on the outer surface of the box body, and the electromagnetic suction cup is adsorbed correspondingly to the iron sheets on the inner walls on both sides of the upper end of the protective cover.

[0009] As a preferred embodiment of the present invention, the shaft is in the shape of a cylindrical boss, the upper outer diameter of the shaft is smaller than the lower outer diameter, the lower outer surface of the shaft is provided with a thread, the inner wall of the hole in the vertical center of the paddle seat is provided with a thread, and the central hole of the paddle seat and the thread below the shaft can be adapted for threaded connection.

[0010] As a preferred solution of the present invention, the shaft is located below the lowest end thread and a limit block is fixedly installed. The initial position of the propeller seat is sleeved above the outer ring thread of the shaft and is not connected to the outer ring thread below the shaft. The rotor seat of the main rotor is fixedly installed above the shaft through a connecting piece.

[0011] As a preferred solution of the present invention, through holes are provided at both symmetrical ends of the outer ring of the rotating bearing, and threaded holes are provided at the bottom of the output ends of the two electric push rods. The output ends of the electric push rods correspond to the through holes of the outer ring of the rotating bearing and are fixedly connected by bolts. The top cover of the box body is covered with a box cover, and the electric push rods are fixedly connected to the box cover.

[0012] As a preferred solution of the present invention, a partition seat is provided at the bottom of the body, a small air pump is fixedly installed on the upper end of the partition seat, the upper end of the partition seat is embedded in the bottom of the body and fixedly connected, and a floating mechanism is provided below the bottom of the partition seat.

[0013] As a preferred embodiment of the present invention, the floating mechanism includes a base plate, and baffles are rotatably installed on all four sides of the upper surface of the base plate. The maximum expansion angle of the baffles is one hundred and eighty degrees. A magnet is embedded in the top of each baffle, and iron blocks are embedded in all four sides of the bottom of the partition seat, corresponding to the position of each magnet. Air bags are provided on the upper surface of the base plate and inside the baffles on all four sides.

[0014] As a preferred embodiment of the present invention, the top and bottom of the airbag are made of hard plastic plates, and the surrounding area is made of nylon material. A plurality of limiting tubes are fixedly installed inside the airbag, and the bottom of the base plate is connected to the bottom of the partition seat through a screw passing through the corresponding limiting tube. An air intake connector is fixedly installed above the airbag, and the air intake connector is connected to the output end of a small air pump.

[0015] In the above technical solution, the technical effects and advantages provided by the present invention are: 1. By setting up two sets of rotors, the main rotor and the aileron, the main rotor provides the main lift during normal flight. The aileron is stored in a protective cover and fixed to the box by an electromagnetic suction cup. It does not participate in power output, reducing aerodynamic drag. When the main rotor breaks due to impact, fatigue, or abnormal lift, the system quickly triggers the emergency mechanism. The electromagnetic suction cup is powered off to release the protective cover, and the electric push rod pushes the outer ring of the rotating bearing downward, driving the propeller seat to descend along the thread of the shaft and lock it, so that the aileron enters the working position. At this time, the motor drives the shaft to rotate the aileron, quickly compensating for lift loss and preventing the fuselage from becoming unbalanced and out of control. 2. The floating mechanism at the bottom of the fuselage allows it to be folded and stored during normal flight without adding additional resistance. When there is a risk of crash, a small air pump inflates the airbag within seconds, and at the same time, the airbag expands around it, pushing the baffle to unfold, causing the airbag to expand beyond the size of the fuselage. It can carry the weight of the entire aircraft and float on the water, preventing the drone from sinking after falling into the water. It is especially suitable for water operations or flights near water. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction to the drawings required for use in the embodiments will be given below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0017] Figure 1 A first perspective perspective view of the overall structure of the present invention; Figure 2 A second perspective perspective view of the overall structure of the present invention; Figure 3 This is an exploded view from the first perspective of the overall structure of the present invention; Figure 4 An exploded view from a second perspective of the overall structure of the present invention; Figure 5 A cross-sectional view of the housing and the shaft of the present invention from a first perspective; Figure 6 A second perspective cross-sectional view of the housing and shaft of the present invention; Figure 7 is a cross-sectional view of the floating mechanism of the present invention; Figure 8 This is an expanded view of the floating mechanism of the present invention; Figure 9 A perspective view of the rotary bearing and the electric push rod of the present invention; Figure 10 For the present invention Figure 3 Magnified view of area A.

[0018] Description of reference numerals: 1. Body; 11. Main arm; 12. Auxiliary arm; 13. Machine base; 14. Motor; 2. Box body; 21. Box cover; 22. Electric push rod; 23. Threaded hole; 24. Electromagnetic suction cup; 25. Protective cover; 26. Iron sheet; 3. Shaft; 31. Main rotor; 32. Auxiliary rotor; 33. Propeller seat; 34. Rotating bearing; 35. Through hole; 36. Limit block; 4. Partition seat; 41. Small air pump; 5. Floating mechanism; 51. Bottom plate; 52. Baffle; 53. Magnet; 54. Airbag; 55. Limit tube; 56. Inlet connector. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0020] The present invention provides Figure 1-10 The quad-rotor drone shown includes a body 1, with main arms 11 fixedly mounted laterally at the four upper corners of the body 1, and secondary arms 12 fixedly mounted at the four upper corners of the body 1 and below each main arm 11, and a box 2 fixedly mounted at the front end of each main arm 11; A shaft 3 is vertically mounted in the middle of each box 2. A main rotor 31 is provided on the top of the box 2. A propeller seat 33 is movably mounted on the lower end of the shaft 3 and located below the bottom of the box 2. Auxiliary rotors 32 are fixedly mounted on both sides of the propeller seat 33. A rotary bearing 34 is provided between the top of the paddle seat 33 and the bottom of the box body 2. The top of the paddle seat 33 is fixedly connected to the inner ring of the rotary bearing 34. Electric push rods 22 are provided on both sides of the interior of the box body 2. The output end of each electric push rod 22 passes through the bottom of the box body 2 and is connected to the two ends of the outer ring of the rotary bearing 34. A protective cover 25 is provided on the outside of each box body 2 . The protective cover 25 is located below the main rotor 31 and covers the outside of the auxiliary rotor 32 .

[0021] In this embodiment, the main arm 11 is fixed laterally at the four corners above the fuselage 1, and the auxiliary arm 12 is installed below it. The double-layer arm structure of the main arm 11 and the auxiliary arm 12 disperses the torque and vibration during the rotation of the rotor, preventing the single arm from bending or breaking due to concentrated force, and the bending strength is improved compared to the traditional single arm. When the UAV is maneuvering at high speed, the lateral force generated by the main rotor 31 is transmitted to the fuselage 1 through the main arm 11, and the auxiliary arm 12 simultaneously bears the reaction force of the motor 14. The two work together to disperse the stress to the entire fuselage 1 and prevent the root of the arm from cracking. The main rotor 31 set at the front end of the main arm 11 provides normal flight lift, and the auxiliary rotor 32 serves as a redundant backup. When the main rotor 31 is damaged, it can be quickly switched to compensate for the lift loss and avoid imbalance and loss of control. If the main rotor 31 breaks due to hitting a tree, the flight control detects a sudden drop in lift, the electromagnetic suction cup 24 is powered off to release the protective cover 25, the electric push rod 22 pushes the rotating bearing 34, and then drives the propeller seat 33 to move down along the shaft 3 thread and lock it, the auxiliary rotor 32 is started, and the drone maintains stable flight.

[0022] Furthermore, in the above technical solution, a base 13 is fixedly installed at the front end of each auxiliary arm 12, a motor 14 is fixedly installed in each base 13, the bottom end of the shaft 3 is fixedly connected to the output end of the motor 14, and the upper end of the shaft 3 passes through the inner ring of the rotating bearing 34 and is fixedly connected to the inner wall of the inner ring of the rotating bearing 34.

[0023] In this embodiment, the shaft 3 is cylindrical and boss-shaped, with a threaded lower end that mates with the threads of the propeller seat 33. The boss-shaped shaft 3 balances lightweight and rigidity, while the threaded connection ensures the firmness of the aileron 32 during switching. The rotating bearing 34 enables the independent rotation of the shaft 3 and the push of the electric push rod 22 to avoid motion interference. When the motor 14 drives the shaft 3 to rotate, the inner ring of the rotating bearing 34 rotates synchronously with the shaft 3, while the outer ring is pushed by the electric push rod 22 to maintain translation, ensuring that the aileron 32 does not affect the rotation of the shaft 3 during the switching process and can accurately lock the working position.

[0024] Furthermore, in the above technical solution, iron sheets 26 are fixedly installed on the inner walls on both sides of the upper end of the protective cover 25, and electromagnetic suction cups 24 are fixedly installed on both sides of the front end of the box body 2. The output end of the electromagnetic suction cup 24 is located on the outer surface of the box body 2, and the electromagnetic suction cup 24 is adsorbed correspondingly to the iron sheets 26 on the inner walls on both sides of the upper end of the protective cover 25.

[0025] In this embodiment, the protective cover 25 covers the aileron 32, isolating the aileron 32 from damage by dust and foreign objects when not in operation. In particular, when the main rotor 31 collides with foreign objects, the protective cover 25 prevents foreign objects from hitting the aileron 32, effectively protecting the aileron 32. The flight control system in the fuselage 1 then controls the on and off of the electromagnetic suction cup 24, allowing the protective cover 25 to be quickly unlocked within milliseconds. The protective cover 25 quickly falls off under the action of its own gravity and airflow, without delaying emergency switching. After the protective cover 25 automatically falls off, the aileron 32 starts unimpeded, thereby preventing the protective cover 25 from affecting the airflow during the rotation of the aileron 32. At the same time, the protective cover 25 adopts a hollow structure, which can reduce the weight of the protective cover 25 and reduce the weight of the drone.

[0026] Furthermore, in the above technical solution, the shaft rod 3 is in the shape of a cylindrical boss, the upper outer diameter of the shaft rod 3 is smaller than the lower outer diameter, the lower outer surface of the shaft rod 3 is provided with a thread, and the inner wall of the hole in the vertical center of the paddle seat 33 is provided with a thread, and the central hole of the paddle seat 33 and the thread below the shaft rod 3 can be adapted to be threadedly connected.

[0027] Furthermore, in the above technical solution, a limit block 36 is fixedly installed below the lowest thread of the shaft 3, and the initial position of the propeller seat 33 is sleeved above the outer circle thread of the shaft 3 and is not connected to the outer circle thread below the shaft 3. The rotor seat of the main rotor 31 is fixedly installed above the shaft 3 through a connecting piece.

[0028] Furthermore, in the above technical solution, through holes 35 are opened symmetrically at both ends of the outer ring of the rotating bearing 34, and threaded holes 23 are opened at the bottom of the output ends of the two electric push rods 22. The output ends of the electric push rods 22 correspond to the through holes 35 of the outer ring of the rotating bearing 34, and are fixedly connected by bolts. The top cover of the box body 2 is installed with a box cover 21, and the electric push rods 22 are fixedly connected to the box cover 21.

[0029] In this embodiment, the output end of the electric push rod 22 is connected to the outer ring of the rotary bearing 34, and a stopper 36 is provided at the lower end of the shaft 3. The linear drive of the electric push rod 22 ensures that the propeller seat 33 moves smoothly downward along the threads of the shaft 3, while the stopper 36 prevents excessive movement of the propeller seat 33. When the main rotor 31 fails and the aileron 32 is switched to the main rotor 31, the electric push rod 22 extends, pushing the rotary bearing 34 and the propeller seat 33 downward. When the lower end of the propeller seat 33 contacts the threads of the shaft 3, the propeller seat 33 drives the inner ring of the rotary bearing 34 to rotate synchronously, while the outer ring of the rotary bearing 34 rotates. When the bottom surface of the propeller seat 33 contacts the upper surface of the stopper 36, the electric push rod 22 automatically stops, and the propeller seat 33 is locked to the lower end of the shaft 3, completing the installation and connection between the aileron 32 and the shaft 3. The housing 2 provides protection for the electric push rod 22, the rotary bearing 34, and other components, isolating them from external dust and moisture. The housing cover 21 facilitates access to internal components and enhances the structural rigidity of the housing 2. When maintenance on the electric actuator 22 is required, the cover 21 can be removed for direct access without disassembling the entire machine, shortening maintenance time. Furthermore, both the main arm 11 and the auxiliary arm 12 are hollow, facilitating easy access to wiring for components such as the motor 14 and the electric actuator 22.

[0030] Furthermore, in the above technical solution, a partition seat 4 is provided at the bottom of the body 1, a small air pump 41 is fixedly installed on the upper end of the partition seat 4, the upper end of the partition seat 4 is embedded in the bottom of the body 1 and fixedly connected, and a floating mechanism 5 is provided below the bottom of the partition seat 4.

[0031] Furthermore, in the above technical solution, the floating mechanism 5 includes a base plate 51, and baffles 52 are rotatably installed on all four sides of the upper surface of the base plate 51. The maximum deployment angle of the baffles 52 is one hundred and eighty degrees. A magnet 53 is embedded in the top of each baffle 52, and iron blocks are embedded in all four sides of the bottom of the partition seat 4, corresponding to the position of each magnet 53. Air bags 54 are provided on the upper surface of the base plate 51 and inside the baffles 52 on all four sides.

[0032] Furthermore, in the above technical solution, the top and bottom of the airbag 54 are made of hard plastic plates, and the surrounding area is made of nylon material. A plurality of limiting tubes 55 are fixedly installed inside the airbag 54. The bottom of the base plate 51 is connected to the bottom of the partition seat 4 through a screw passing through the corresponding limiting tube 55. An air intake connector 56 is fixedly installed above the airbag 54, and the air intake connector 56 is connected to the output end of the small air pump 41.

[0033] In this embodiment, the partition seat 4 at the bottom of the body 1 is connected to the floating mechanism 5, which includes a foldable baffle 52, an airbag 54 and a small air pump 41. The baffle 52 is adsorbed to the bottom of the partition seat 4 by magnets 53. Under normal circumstances, the baffles 52 on the four sides are folded and stored vertically without increasing resistance, while preventing the airbag 54 inside from leaking out and avoiding damage around the airbag 54. If a crash occurs, the small air pump 41 is immediately started to inflate the airbag 54. As the airbag 54 inflates, the airbag 54 expands and unfolds. As the airbag 54 becomes larger, it contacts the inner walls of the baffles 52 on all sides. When the airbag 54 expands to its maximum size, the baffles 52 on all sides expand completely parallel to each other, and the airbag 54 carries the entire machine to float on the water surface, preventing it from sinking. This protects the battery and most other electronic components inside the body 1 from water immersion, reducing losses.

[0034] The working process of the quad-rotor drone provided by the present invention when in use is as follows: The flight control system is calibrated through the ground station software, and the fault threshold of the main rotor 31 is set, such as the lift drop range or abnormal vibration frequency to trigger the switching of the auxiliary rotor 32, and the parameters such as the extension and retraction stroke of the electric push rod 22 and the on-off response time of the electromagnetic suction cup 24 are confirmed.

[0035] During normal flight, motor 14 drives shaft 3 to rotate, causing main rotor 31 to rotate at high speed to provide lift. The drone achieves attitude control, such as turning and pitching, through the speed difference of main rotor 31. Auxiliary rotor 32 is normally housed within protective cover 25. Propeller mount 33 is sleeved above the threads of shaft 3 and located below the bottom of housing 2, without contacting shaft 3 or the threads below it. During this time, both the inner and outer rings of rotary bearing 34 are stationary, and electric actuator 22 is in its original, retracted state.

[0036] If the main rotor 31 experiences a collision, fatigue fracture, or abnormal lift, the system triggers a control action. The flight control system detects a sudden drop in lift, a fuselage tilt angle exceeding a certain angle, or an abnormal vibration frequency, such as one deviating from the normal range, through sensors. It then confirms a fault in the main rotor 31. The flight control system then immediately de-energizes the electromagnetic chuck 24, separating the iron plate 26 from the front suction cup of the electromagnetic chuck 24. The protective cover 25 falls away under the influence of gravity and airflow, revealing the auxiliary rotor 32.

[0037] Simultaneously, the electric push rod 22 extends, pushing the outer ring of the rotary bearing 34 downward. Since the inner and outer rings of the rotary bearing 34 rotate synchronously, the inner ring of the rotary bearing 34 drives the propeller seat 33 downward along the threads of the shaft 3. As the shaft 3 continues to rotate, driven by the motor 14, the propeller seat 33 engages with the shaft 3 threads and locks until the bottom hits the stop block 36, stopping the propeller seat 33. The motor 14 drives the shaft 3, which in turn rotates the aileron 32. The flight control system simultaneously adjusts the speed of the other rotors to balance the aircraft's attitude and tilt correction, ensuring stable flight or a safe return.

[0038] If the drone's main rotor 31 malfunctions and the auxiliary rotor 32 is activated for a smooth landing, the propeller seat 33 needs to be reset to its initial position. The fallen protective cover 25 is then retrieved and cleaned. If damaged, it is replaced with a new one and then re-secured using the electromagnetic chuck 24. The air in the airbag 54 is then released, and the baffle 52 is folded and secured using the magnet 53.

[0039] When the drone is out of control, the power system fails, or there is a risk of crashing. The flight control triggers the small air pump 41 to work, and the airbag 54 is inflated through the air inlet connector 56. The airbag 54 expands rapidly within a few seconds. During the expansion of the airbag 54, the surrounding baffles 52 are pushed to rotate around the bottom plate 51, the magnet 53 is separated from the iron block of the partition seat 4, and the baffle 52 is unfolded to a 180° horizontal state. If it falls on the water, ensure that the drone floats in a horizontal posture, and the several baffles 52 that are unfolded to a horizontal state also play a floating role on the water surface, preventing a large amount of water from entering the body 1, causing all the internal components of the body 1 to be damaged by water.

[0040] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A quadrotor drone, comprising a body (1), characterized in that: Main arms (11) are fixedly installed transversely at the four upper corners of the body (1), and auxiliary arms (12) are fixedly installed at the four upper corners of the body (1) and below each main arm (11), and a box (2) is fixedly installed at the front end of each main arm (11); A shaft (3) is vertically rotatably mounted in the middle of each box (2), a main rotor (31) is provided above the top of the box (2), a propeller seat (33) is movably sleeved at the lower end of the shaft (3) and located below the bottom of the box (2), and auxiliary rotors (32) are fixedly mounted on both sides of the propeller seat (33); A rotary bearing (34) is provided between the top of the paddle seat (33) and the bottom of the box (2), the top of the paddle seat (33) is fixedly connected to the inner ring of the rotary bearing (34), and electric push rods (22) are provided on both sides of the interior of the box (2), and the output end of each electric push rod (22) passes through the bottom of the box (2) and is connected to both ends of the outer ring of the rotary bearing (34); A protective cover (25) is provided on the outside of each box (2), and the protective cover (25) is located below the main rotor (31) and covers the outside of the auxiliary rotor (32).

2. A quadrotor drone according to claim 1, characterized in that: A base (13) is fixedly mounted on the front end of each auxiliary arm (12), a motor (14) is fixedly mounted in each base (13), the bottom end of the shaft (3) is fixedly connected to the output end of the motor (14), and the upper end of the shaft (3) passes through the inner ring of the rotary bearing (34) and is fixedly connected to the inner wall of the inner ring of the rotary bearing (34).

3. The quadrotor drone according to claim 1, characterized in that: Iron sheets (26) are fixedly mounted on both inner walls of the upper end of the protective cover (25), and electromagnetic suction cups (24) are fixedly mounted on both sides of the front end of the box (2). The output end of the electromagnetic suction cup (24) is located on the outer surface of the box (2), and the electromagnetic suction cup (24) is adsorbed correspondingly to the iron sheets (26) on the inner walls of both sides of the upper end of the protective cover (25).

4. The quadrotor drone according to claim 1, characterized in that: The shaft (3) is in the shape of a cylindrical boss, the outer diameter of the upper portion of the shaft (3) is smaller than the outer diameter of the lower portion, a thread is provided on the lower outer surface of the shaft (3), a thread is provided on the inner wall of the hole in the vertical center of the paddle seat (33), and the central hole of the paddle seat (33) and the thread below the shaft (3) can be adapted for threaded connection.

5. The quadrotor drone according to claim 1, characterized in that: The shaft (3) is fixedly mounted with a limit block (36) below the lowest thread. The initial position of the propeller seat (33) is sleeved above the outer thread of the shaft (3) and is not connected to the outer thread below the shaft (3). The rotor seat of the main rotor (31) is fixedly mounted above the shaft (3) via a connecting piece.

6. The quadrotor drone according to claim 1, characterized in that: Through holes (35) are symmetrically provided at both ends of the outer ring of the rotary bearing (34), and threaded holes (23) are provided at the bottom of the output ends of the two electric push rods (22). The output ends of the electric push rods (22) correspond to the through holes (35) of the outer ring of the rotary bearing (34) and are fixedly connected by bolts. The top of the box body (2) is covered with a box cover (21), and the electric push rods (22) are fixedly connected to the box cover (21).

7. The quadrotor drone according to claim 1, characterized in that: A partition seat (4) is provided at the bottom of the machine body (1), a small air pump (41) is fixedly mounted on the upper end of the partition seat (4), the upper end of the partition seat (4) is embedded in the bottom of the machine body (1) and is fixedly connected, and a floating mechanism (5) is provided below the bottom of the partition seat (4).

8. The quadrotor drone according to claim 7, characterized in that: The floating mechanism (5) includes a bottom plate (51), baffles (52) are rotatably mounted on the upper surface of the bottom plate (51), the maximum deployment angle of the baffles (52) is one hundred and eighty degrees, a magnet (53) is embedded in the top of each baffle (52), iron blocks are embedded in the bottom of the partition seat (4) and correspond to the position of each magnet (53), and air bags (54) are provided on the upper surface of the bottom plate (51) and inside the baffles (52) on all sides.

9. The quadrotor drone according to claim 8, characterized in that: The top and bottom of the airbag (54) are made of hard plastic plates, and the surrounding area is made of nylon material. A plurality of limiting tubes (55) are fixedly installed inside the airbag (54). The bottom of the bottom plate (51) is connected to the bottom of the partition seat (4) through a screw passing through the corresponding limiting tube (55). An air intake connector (56) is fixedly installed above the airbag (54), and the air intake connector (56) is connected to the output end of the small air pump (41).

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