Retractable nose landing gear of unmanned aerial vehicle and unmanned aerial vehicle

Abstract

The retractable nose landing gear comprises an actuator and a shock absorber, the telescopic end of the shock absorber is connected with a tire, the actuator is rotationally connected with a fuselage, and the output end of the actuator is in transmission connection with the shock absorber through a retractable connecting rod and can drive the shock absorber to rotate relative to the fuselage. The shock absorber comprises an outer cylinder and an inner cylinder capable of sliding and rotating relative to the outer cylinder. According to the shock absorber, the normally-open hole and the one-way through hole are formed in the horizontal section of the inner cylinder, it is guaranteed that forward damping and reverse damping of the shock absorber are achieved through the structure, and the landing buffering function and the sliding damping function are both considered.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft landing gears, and more specifically to a retractable front landing gear of an unmanned aerial vehicle and the unmanned aerial vehicle. Background Art

[0002] The landing gear is a key component in the take-off and landing process of the drone, used to consume and absorb the energy of the aircraft during landing and braking. The landing gear of traditional fixed-wing small drones is usually fixed due to factors such as space layout, flight time, and weight. This type of landing gear has a great impact on the aerodynamic shape of the aircraft, increases flight resistance, and affects the flight time of the drone.

[0003] Most of the existing landing gears of small domestic UAVs use spring shock-absorbing landing gears, and most of them are non-retractable or retractable but with complex self-locking mechanisms and high manufacturing costs. Although the cost of spring shock-absorbing landing gear is relatively low, its shock-absorbing and buffering performance is poor. The buffering effect is different for UAVs of different weights, and the springs need to be constantly replaced for debugging and adaptation. The oil and gas buffers used in some domestic UAVs have complex structures, a large number of parts, high manufacturing difficulty and high manufacturing costs, and are not suitable for the development and application of low-cost, serialized UAVs.

[0004] Patent document with patent publication number CN103523212A discloses a front landing gear of an aircraft, wherein the front landing gear is installed on the aircraft structure by two mounting shafts on the buffer strut, and the front landing gear can rotate around the mounting shaft; one end of the retracting strut actuator cylinder has a joint bearing, which is connected to the shaft of the buffer strut and fixed by a nut; the other end of the retracting strut actuator cylinder is installed on the body structure joint through a threaded shaft; the wheel fork is installed on the inner tube of the buffer strut by bolts; the wheel and tire are installed on the wheel fork with a wheel axle; the upper end of the upper anti-twist arm is installed on the ring body joint; the lower end of the lower anti-twist arm is installed on the joint of the wheel fork; the upper anti-twist arm and the lower anti-twist arm are connected by a quick release pin. This solution has a simple structure and complete functions while ensuring the strength and rigidity of the landing gear, and is suitable for small aircraft. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to realize the integration of landing cushioning and sliding vibration reduction of the landing gear and adapt to the cushioning requirements of different impact loads.

[0006] The present invention solves the above technical problems through the following technical means: a retractable front landing gear of an unmanned aerial vehicle, comprising an actuator and a shock absorber, wherein the retractable end of the shock absorber is connected to a tire, the actuator is rotatably connected to a fuselage, the output end of the actuator is transmission-connected to the shock absorber through a retractable connecting rod, and can drive the shock absorber to rotate relative to the fuselage, the shock absorber comprises an outer cylinder and an inner cylinder capable of sliding and rotating relative to the outer cylinder, a closed cavity is provided in the outer cylinder, the cavity is filled with aviation hydraulic oil and air, and a horizontal section of the inner cylinder extending into the inner cavity of the outer cylinder divides the cavity into an upper cavity and an The inner tube is provided with a normally open hole and a one-way conducting hole connecting the upper cavity and the lower cavity, and the retractable connecting rod comprises an upper connecting rod and a lower connecting rod, one end of the upper connecting rod is rotatably connected to the fuselage through a connecting rod support, and the other end is rotatably connected to the lower connecting rod, the output end of the actuator is rotatably connected to the upper connecting rod, the end of the lower connecting rod facing away from the upper connecting rod is rotatably connected to the outer tube, the end of the outer tube facing away from the inner tube is rotatably connected to the fuselage, and the connection point between the upper connecting rod and the lower connecting rod is not located on the line between the connection point between the upper connecting rod and the fuselage and the connection point between the lower connecting rod and the outer tube.

[0007] As a preferred technical solution, a push rod is provided on the upper connecting rod, and a retractable sensor adapted to the push rod is fixedly connected to one end of the connecting rod support facing the upper connecting rod.

[0008] As a preferred technical solution, a stop block is also provided at one end where the lower connecting rod is rotatably connected to the upper connecting rod.

[0009] As a preferred technical solution, one end of the outer cylinder facing away from the inner cylinder is fixedly connected with a buffer pillar, and two through shafts are arranged on the buffer pillar, and through shafts are provided with through shaft oiling nozzles.

[0010] As a preferred technical solution, a steering servo is fixedly connected to the outer cylinder, a steering collar is rotatably connected to the outer cylinder, the output end of the steering servo is transmission-connected to the steering collar, and can drive the steering collar to rotate about the axis of the outer cylinder as the rotating shaft, the steering collar is fixedly connected to a wheel fork, and the tire is rotatably mounted on the wheel fork.

[0011] As an optimal technical solution, the output end of the steering servo is fixedly connected to a rocker arm mounting flange, the rocker arm mounting flange is fixedly connected to one end of the servo rocker arm, and the other end of the servo rocker arm is rotatably connected to the steering sleeve ring through a connecting rod, and both ends of the connecting rod are ball bearings.

[0012] As a preferred technical solution, the steering collar is rotatably coordinated with the wheel fork through a swing reducer arm, the swing reducer arm includes an upper swing arm and a lower swing arm, one end of the upper swing arm is rotatably connected to the steering collar, and the other end is rotatably connected to one end of the lower swing arm, and the other end of the lower swing arm is rotatably connected to the wheel fork.

[0013] As an optimal technical solution, a cylinder sleeve is installed between the inner cylinder and the outer cylinder. The cylinder sleeve is fixedly connected to the inner wall of the bottom of the outer cylinder. Two layers of O-rings are provided inside and outside the cylinder sleeve, and a felt ring is provided on the mating surface of the cylinder sleeve and the vertical section of the inner cylinder.

[0014] As a preferred technical solution, four oil holes are opened on the inner cylinder, two of which are provided with flow control bolts to form unidirectional conducting holes, and the other two oil holes are formed as normally open holes.

[0015] The present invention also provides a UAV, comprising the retractable front landing gear of the UAV.

[0016] The beneficial effects of the present invention are:

[0017] (1) In the present invention, a normally open hole and a one-way conducting hole are provided on the horizontal section of the inner tube. This structure ensures that the forward damping and reverse damping of the shock absorber are realized, taking into account the landing buffer and the sliding vibration reduction functions. Specifically, when the aircraft lands, i.e., when compressed: the shock absorber is compressed by impact due to the influence of gravity. The shock absorber is filled with nitrogen, which acts as a spring and stores energy. The oil passes through the two normally open holes and the two one-way conducting holes at an extremely high speed, absorbing a large amount of impact energy and converting them into heat energy, so that the aircraft stabilizes after landing. When extended: to prevent the nose of the aircraft from bouncing after landing, Because the cavity contains compressed gas after compression, the piston is extended, and the oil can only pass through two normally open small holes, which slows down the speed of piston extension and enables the aircraft to land smoothly without bouncing; through the setting of the retracting and extending connecting rod, the deployment stiffness is guaranteed while reducing the size and load of the driver, reducing the system failure rate, and the retracting and extending trajectory is stable and controllable; the connection point between the upper connecting rod and the lower connecting rod is not located on the line between the connection point between the upper connecting rod and the fuselage and the connection point between the lower connecting rod and the outer tube, so that there is an eccentric torque after the landing gear is fully lowered, and the state of the front landing gear will not change in the absence of external force.

[0018] (2) In the present invention, by providing the stopper, the push rod, and the retracting / releasing in place sensor, the retracting / releasing connecting rod can have a self-locking function, thereby improving the stability and safety of the aircraft after landing.

[0019] (3) In the present invention, two O-rings are arranged inside and outside the cylinder liner to ensure the sealing effect of the hydraulic oil and air in the cavity. A felt ring is installed at the bottom of the cylinder liner. The function of the felt ring is to keep the side wall of the inner cylinder clean and prevent foreign matter from entering the landing gear buffer system and damaging the internal structure of the landing gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the oil and gas cushioned retractable front landing gear structure;

[0021] Figure 2 This is a schematic diagram of the structure of the retractable and in-place monitoring system for the oil and gas cushioned retractable front landing gear;

[0022] Figure 3 This is a schematic diagram of the steering mechanism structure of the oil-gas buffered retractable front landing gear;

[0023] Figure 4 It is a top view of the cross-sectional view of the oil-gas buffered retractable front landing gear buffer mechanism;

[0024] Figure 5 It is a front cross-sectional view of the oil-gas buffered retractable front landing gear buffer mechanism;

[0025] Figure 6 This is a schematic diagram of the oil-gas cushioned retractable front landing gear in the retracted state;

[0026] Figure numbers: 1. Retractable sensor; 2. Push rod; 3. Upper connecting rod; 4. Lower connecting rod; 5. Steering servo mounting bracket; 6. Steering collar grease nozzle; 7. Cylinder sleeve fixing ring; 8. Inner cylinder; 9. Wheel fork; 10. Wheel axle; 11. Connecting rod support; 12. Actuator; 13. Through-shaft grease nozzle; 14. Through-shaft; 15. Outer cylinder; 16. Steering servo; 17. Upper swing arm; 18. Lower swing arm; 19. Wheel hub; 20. Tire; 21. Rocker arm mounting flange; 22. Steering servo rocker arm; 23. Connecting rod; 24. Steering collar; 25. Hydraulic oil grease nozzle; 26. Spring; 27. Cylinder sleeve; 28. Cavity; 29. ​​Flow control bolt; 30. Nylon felt ring; 31. O-ring; 32. Felt ring; 33. Oil hole; 34. Stop block. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figure 1 , Figure 5A retractable front landing gear of an unmanned aerial vehicle comprises an actuator 12 and a shock absorber. The retractable end of the shock absorber is connected to a tire 20. The actuator 12 is rotatably connected to a fuselage. The output end of the actuator 12 is transmission-connected to the shock absorber through a retractable connecting rod and can drive the shock absorber to rotate relative to the fuselage. The shock absorber comprises an outer cylinder 15 and an inner cylinder 8 that can slide and rotate relative to the outer cylinder 15. A sealed cavity 28 is provided in the outer cylinder 15. Aviation hydraulic oil and air are filled in the cavity 28. The horizontal section of the inner cylinder 8 extending into the inner cavity of the outer cylinder 15 divides the cavity 28 into an upper cavity and a lower cavity. A normally open hole and a one-way conducting hole connecting the upper cavity and the lower cavity are also provided on the horizontal section of the cylinder 8; in the present embodiment, four oil holes 33 are provided on the inner cylinder 8, which are distributed at equal angles along the center of the inner cylinder 8, but the number and arrangement are not limited thereto. Two of the oil holes 33 are provided with flow control bolts 29 and form one-way conducting holes, and the other two oil holes 33 form normally open holes. The flow control bolts 29 are prior art. When the landing gear rebounds, the flow control bolts 29 block the oil holes 33 under the action of the hydraulic oil, thereby changing the flow of the hydraulic oil in and out to achieve a buffering function.

[0029] The head of the flow control bolt 29 is elastically connected to the upper surface of the horizontal section of the inner tube 8 through the spring 26. One end of the spring 26 is fixedly connected to the head of the flow control bolt 29, and the other end is fixedly connected to the horizontal section of the inner tube 8. The flow control bolt 29 extends through the oil hole 33 and extends to one end of the lower cavity and is fixedly connected with a nut. A gasket is also provided between the nut and the lower surface of the horizontal section of the inner tube 8. The spring 26 is mainly used to control the opening and closing of the two variable oil holes, thereby controlling the flow rate of the hydraulic oil during compression and extension, playing a buffering role and reducing rebound. The spring 26 is located on the outside of the rod of the flow control bolt 29. In the static state, the gasket and the nut are tightly attached to the lower surface of the inner tube 8 under the action of the spring 26. When the landing gear is compressed, the oil can overcome the elastic force and pass through the one-way guide hole. When extended, the gasket and the lower surface of the inner tube 8 are attached to the one-way guide hole in a closed state, reducing the flow of hydraulic oil to prevent too fast rebound.

[0030] This structure ensures that the forward damping and reverse damping of the shock absorber are achieved, taking into account the landing buffer and taxiing vibration reduction functions. Specifically, when the aircraft lands, i.e., is compressed: the shock absorber is compressed by impact due to the influence of gravity. The shock absorber is filled with nitrogen, which acts as a spring to store energy. The oil passes through the two normally open holes and the two one-way conducting holes at an extremely high speed, absorbing a large amount of impact energy and converting them into heat energy, so that the aircraft can stabilize after landing. When extending: in order to prevent the nose of the aircraft from bouncing after landing, the cavity contains compressed gas after compression, so that the piston, i.e., the inner cylinder 8, is extended, and the oil can only pass through the two normally open small holes, which slows down the speed of the piston extension, so that the aircraft can land smoothly without bouncing.

[0031] See also Figure 1 , Figure 2The retractable connecting rod includes an upper connecting rod 3 and a lower connecting rod 4. One end of the upper connecting rod 3 is rotatably connected to the fuselage through a first rotating shaft and a connecting rod support 11, and the other end is rotatably connected to the lower connecting rod 4 through a second rotating shaft. The output end of the actuator 12 is rotatably connected to the upper connecting rod 3, and the end of the lower connecting rod 4 away from the upper connecting rod 3 is rotatably connected to the outer cylinder 15 through a third rotating shaft. A hydraulic oil injection nozzle 25 is provided on the outer cylinder 15. The hydraulic oil injection nozzle 25 is connected to the inner cavity of the outer cylinder 15, that is, connected to the upper cavity and the lower cavity. Aviation hydraulic oil and compressed air are injected through the hydraulic oil injection nozzle 25. The end of the outer tube 15 facing away from the inner tube 8 is rotatably connected to the fuselage, and the connection point between the upper connecting rod 3 and the lower connecting rod 4 is not located on the line between the connection point between the upper connecting rod 3 and the fuselage and the connection point between the lower connecting rod 4 and the outer tube 15, that is, the second rotating shaft is not on the line between the center points of the first rotating shaft and the third rotating shaft, or the line between the axis of the first rotating shaft and the axis of the second rotating shaft and the line between the axis of the second rotating shaft and the axis of the third rotating shaft have an angle, so that there is an eccentric moment after the landing gear is fully lowered, and the state of the front landing gear will not change in the absence of external force. Thereby improving the stability and safety of the aircraft after landing, the upper connecting rod 3 is fixedly connected with a push rod 2, and the end of the connecting rod support 11 facing the upper connecting rod 3 is fixedly connected with a retractable position sensor 1 adapted to the push rod 2, when the push rod 2 contacts the retractable position sensor 1, it is in a retracted state, and when it does not contact, it is in an extended or lowered state, such as Figure 6 As shown, after the aircraft takes off, the front landing gear is retracted into the fuselage under the action of the retracting actuator 12, and a push rod 2 is arranged at the end of the retracting upper connecting rod 3. The push rod 2 generates a signal after contacting the retracting position sensor 1. After the flight control computer receives the signal, the ground personnel can accurately and quickly determine the state of the front landing gear based on the signal; a stop block 34 is also provided at one end of the lower connecting rod 4 that is rotatably connected to the upper connecting rod 3. The stop block 34 is mainly used to limit the upper connecting rod 3 so that it has no tendency to continue to move downward, thereby preventing the landing gear from being lowered at an excessive angle.

[0032] One end of the outer cylinder 15 facing away from the inner cylinder 8 is fixedly connected with a buffer pillar, on which two through shafts 14 are provided, and on which through shafts 14 a through shaft oiling nozzle 13 is provided. The buffer pillar is rotatably connected to the fuselage via the through shafts 14 .

[0033] See also Figure 3 , Figure 5, two steering servo mounting brackets 5 are fixedly connected to the outer cylinder 15, a steering servo 16 is fixedly connected to the steering servo mounting bracket 5, a steering sleeve 24 is rotatably connected to the outer cylinder 15, a steering sleeve oiling nozzle 6 is provided on the steering sleeve 24, a cylinder sleeve fixing ring 7 is fixedly connected to the outer cylinder 15, which is used to limit the steering sleeve 24, the output end of the steering servo 16 is transmission-connected to the steering sleeve 24, and can drive the steering sleeve 24 to rotate with the axis of the outer cylinder 15 as the rotating shaft, the steering sleeve 24 is fixedly connected to the wheel fork 9, the tire 20 is rotatably connected to the wheel fork 9 through the wheel axle 10, the wheel axle 10 is rotatably connected to the wheel hub 19, the wheel hub 19 is fixed to the inner ring of the tire 20, and the output end of the steering servo 16 is fixedly connected There is a rocker arm mounting flange 21, which is fixedly connected to one end of a steering gear rocker arm 22. The other end of the steering gear rocker arm 22 is rotatably connected to a steering collar 24 through a connecting rod 23. Both ends of the connecting rod 23 are ball bearings. The steering collar 24 is rotatably matched with the wheel fork 9 through a swing reduction arm. The swing reduction arm includes an upper swing arm 17 and a lower swing arm 18. One end of the upper swing arm 17 is rotatably connected to the steering collar 24, and the other end is rotatably connected to one end of the lower swing arm 18. The other end of the lower swing arm 18 is rotatably connected to the wheel fork 9. When the aircraft lands, the inner cylinder 8 is compressed into the outer cylinder 15 under the action of the gravity of the aircraft, and the angle between the upper swing arm 17 and the lower swing arm 18 is compressed accordingly, and the front wheel of the aircraft can be effectively prevented from swinging, thereby improving the landing stability of the aircraft.

[0034] See also Figure 4 , Figure 5 A cylinder sleeve 27 is installed between the inner cylinder 8 and the outer cylinder 15. The cylinder sleeve 27 is fixedly connected to the inner wall of the bottom of the outer cylinder 15. Two layers of O-rings 31 are arranged radially along the cylinder sleeve 27 on the inside and outside of the cylinder sleeve 27. A felt ring 32 is provided on the mating surface of the cylinder sleeve 27 and the vertical section of the inner cylinder 8. The function of the felt ring 32 is to keep the side wall of the inner cylinder 8 clean and prevent foreign matter from entering the landing gear buffer system and damaging the internal structure of the landing gear. A nylon felt ring 30 is arranged on the side wall of the inner cylinder 8 to ensure the sealing performance of the upper and lower cavities and to play a lubricating role.

[0035] It should be noted that this embodiment also provides a drone including a retractable front landing gear of the drone.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A retractable front landing gear for an unmanned aerial vehicle, comprising an actuator (12) and a shock absorber, wherein the retractable end of the shock absorber is connected to a tire (20), characterized in that: The actuator (12) is rotatably connected to the fuselage. The output end of the actuator (12) is transmission-connected to the shock absorber through a retractable connecting rod and can drive the shock absorber to rotate relative to the fuselage. The shock absorber comprises an outer cylinder (15) and an inner cylinder (8) capable of sliding and rotating relative to the outer cylinder (15). A sealed cavity (28) is provided in the outer cylinder (15). Aviation hydraulic oil and air are filled in the cavity (28). A horizontal section of the inner cylinder (8) extending into the inner cavity of the outer cylinder (15) divides the cavity (28) into an upper cavity and a lower cavity. A normally open hole and a one-way conducting hole for connecting the upper cavity and the lower cavity are also provided on the horizontal section of the inner cylinder (8). The retractable connecting rod comprises an upper connecting rod (3) and a lower connecting rod (4); one end of the upper connecting rod (3) is rotatably connected to the fuselage through a connecting rod support (11), and the other end is rotatably connected to the lower connecting rod (4); the output end of the actuator (12) is rotatably connected to the upper connecting rod (3); the end of the lower connecting rod (4) away from the upper connecting rod (3) is rotatably connected to the outer tube (15); the end of the outer tube (15) away from the inner tube (8) is rotatably connected to the fuselage; and the connection point between the upper connecting rod (3) and the lower connecting rod (4) is not located on the line between the connection point between the upper connecting rod (3) and the fuselage and the connection point between the lower connecting rod (4) and the outer tube (15).

2. The retractable front landing gear of a drone according to claim 1, characterized in that: A push rod (2) is provided on the upper connecting rod (3), and a retractable sensor (1) adapted to the push rod (2) is fixedly connected to one end of the connecting rod support (11) facing the upper connecting rod (3).

3. The retractable front landing gear of a drone according to claim 1, characterized in that: One end of the lower connecting rod (4) rotatably connected to the upper connecting rod (3) is also provided with a stop block (34).

4. The retractable front landing gear of a drone according to claim 1, characterized in that: One end of the outer cylinder (15) facing away from the inner cylinder (8) is fixedly connected with a buffer pillar, and two through shafts (14) are arranged on the buffer pillar, and a through shaft oiling nozzle (13) is arranged on the through shaft (14).

5. The retractable front landing gear of a drone according to claim 1, characterized in that: The outer cylinder (15) is fixedly connected with a steering servo (16), and the outer cylinder (15) is rotatably connected with a steering collar (24). The output end of the steering servo (16) is transmission-connected with the steering collar (24) and can drive the steering collar (24) to rotate around the axis of the outer cylinder (15). The steering collar (24) is fixedly connected with a wheel fork (9), and the tire (20) is rotatably mounted on the wheel fork (9).

6. The retractable front landing gear of a drone according to claim 5, characterized in that: The output end of the steering servo (16) is fixedly connected with a rocker arm mounting flange (21), the rocker arm mounting flange (21) is fixedly connected to one end of a steering servo rocker arm (22), the other end of the steering servo rocker arm (22) is rotatably connected to a steering collar (24) through a connecting rod (23), and both ends of the connecting rod (23) are ball bearings.

7. The retractable front landing gear of a drone according to claim 5, characterized in that: The steering collar (24) is rotatably matched with the wheel fork (9) through a swing reduction arm, the swing reduction arm comprises an upper swing arm (17) and a lower swing arm (18), one end of the upper swing arm (17) is rotatably connected to the steering collar (24), and the other end is rotatably connected to one end of the lower swing arm (18), and the other end of the lower swing arm (18) is rotatably connected to the wheel fork (9).

8. The retractable front landing gear of a drone according to claim 1, characterized in that: A cylinder sleeve (27) is arranged between the inner cylinder (8) and the outer cylinder (15). The cylinder sleeve (27) is fixedly connected to the inner wall of the bottom of the outer cylinder (15). Two layers of O-type sealing rings (31) are arranged inside and outside the cylinder sleeve (27). A felt ring (32) is arranged on the mating surface of the cylinder sleeve (27) and the vertical section of the inner cylinder (8).

9. The retractable front landing gear of a drone according to claim 1, characterized in that: Four oil holes (33) are provided on the inner cylinder (8), two of the oil holes (33) are provided with flow control bolts (29) and form unidirectional conducting holes, and the other two oil holes (33) form normally open holes.

10. A drone, characterized in that: Including a retractable front landing gear of an unmanned aerial vehicle as described in any one of claims 1-9.

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