A single crank flapping-wing aircraft transmission mechanism

Abstract

The single-crank flapping-wing aircraft transmission mechanism of the present invention has a pair of active cranks symmetrically arranged in a V shape, the lower ends of which are fixedly combined, and the combining point is hingedly connected to a first mounting point on the aircraft frame, the upper ends of the pair of active cranks are connected to a pair of connecting rods of equal length and symmetrically arranged, the upper ends of the connecting rods are hingedly connected to the middle parts of a pair of rotating rods, and the lower ends of the pair of rotating rods are hingedly connected to a second mounting point on the aircraft frame, and a spring is fixedly connected between the upper section of the rotating rod on each side and the first mounting point, imitating the internal structure of the existing biological chest cavity, adding an elastic element inside the structure, and utilizing the function of storing and releasing energy of the elastic element to alleviate the problem of excessive energy loss of the transmission mechanism, reduce energy waste, and increase the flight time, with a simple structure and less energy loss during operation.

Description

Technical Field

[0001] The invention relates to a single-crank flapping-wing aircraft transmission mechanism in unmanned aerial vehicle flight technology. Background Art

[0002] A flapping-wing aircraft is an aircraft developed based on the bionic flight principle. Based on traditional fixed-wing and rotorcraft, it integrates the lifting, hovering and propulsion systems in a pair of wings to realize the flight function. It has very good maneuverability and stability during flight, and is widely used in both civilian and military fields. Flapping-wing aircraft in the prior art are mainly bird-like and insect-like. The insect-like type is mainly realized by new transmission mechanisms such as piezoelectric drive, while the slightly larger bird-like flapping-wing aircraft uses traditional single crank or double crank mechanisms to realize the flapping of wings on both sides. Although the single crank mechanism has a small spatial size, there is always a phase difference between the two side wing surfaces, which will affect the control stability. The two side mechanisms of the double rocker mechanism have errors between them and cannot maintain synchronization. It is also large in size, occupies a lot of space, and is inconvenient to carry. There are also defects such as small load capacity, low energy conversion efficiency of the transmission mechanism, and the battery energy carried cannot meet the long-term endurance requirements. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a single-crank flapping-wing aircraft transmission mechanism that can imitate the internal structure of an existing biological thorax, improve the energy conversion efficiency of the transmission mechanism, reduce energy waste, have high phase symmetry and good stability.

[0004] The single crank flapping-wing aircraft transmission mechanism of the present invention is characterized in that: it includes a pair of fixedly connected active cranks, the pair of active cranks are symmetrically arranged in a V shape, the lower ends are fixedly combined, and the combining point is hingedly connected to a first mounting point on the aircraft frame, the upper ends of the pair of active cranks are connected to a pair of connecting rods of equal length and symmetrically arranged, the lower ends of the connecting rods are hingedly connected to the upper ends of the active cranks, the upper ends of the connecting rods are hingedly connected to the middle parts of a pair of rotating rods, the lower ends of the pair of rotating rods are hingedly connected to a second mounting point on the aircraft frame, the pair of rotating rods are equal in length and symmetrically arranged along the second mounting point, the upper section of each side rotating rod is fixedly connected to a spring, the upper end of the spring is fixedly connected to the rotating rod, and the lower end is fixedly connected to the first mounting point;

[0005] In the initial state of the transmission mechanism, the angle between the pair of connecting rods is smaller than the angle between the pair of active cranks;

[0006] The active crank, connecting rod and rotating rod are made of carbon fiber composite materials;

[0007] The upper end of the spring is connected to the upper part of the rotating rod near the upper end;

[0008] The spring is a coil spring;

[0009] The length of the active crank a, the length of the rotating rod b, the length of the connecting rod c and the angle between a pair of active cranks β , the distance d between the first mounting point and the second mounting point, the flapping angle between the upper limit position and the lower limit position of the rotating rod φ The calculation formula is:

[0010]

[0011]

[0012] ;

[0013] Said d =39mm, φ =51°, β =30°, a =7mm, b =38mm, c =16mm.

[0014] The single-crank flapping-wing aircraft transmission mechanism of the present invention imitates the internal structure of the existing biological thorax through a pair of active cranks, connecting rods, rotating rods and springs, and adds elastic elements inside the structure. The elastic elements are used to store and release energy to alleviate the problem of excessive energy loss in the transmission mechanism, reduce energy waste, and increase flight time. The structure is simple and the energy loss during operation is small. When a=7mm, b=38mm, c=16mm, d=39mm, φ=51°, β=30°, the single-crank elastic flapping-wing aircraft transmission mechanism of the present invention can effectively reduce the power peak by 40.3% compared with a traditional mechanism without a spring. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a schematic diagram of the structure of a transmission mechanism of a single crank flapping-wing aircraft according to an embodiment of the present invention, wherein arcs D1E1 and D2E2 are respectively trajectories of the rotating rod ends D1 and D2 during flapping, dashed lines O2E1 and O2E2 are respectively lower limit positions of the rotating rods O2D1 and O2D2 during flapping, solid lines O2D1 and O2D2 are respectively upper limit positions of the rotating rods during flapping, and the angle φ between the two limit positions is the flapping angle;

[0016] In the figure, O1A1 and O1A2 are cranks with a length of a; A1B1 and A2B2 are connecting rods with a length of b;

[0017] O2B1 and O2B2 are joysticks with a length of c; the distance between O1O2 is d. DETAILED DESCRIPTION

[0018] As shown in the figure, a single crank flapping-wing aircraft transmission mechanism, the overall structure of which is the first mounting point O1, the second mounting point O2, the crank one O1A1, the crank two O1A2, the connecting rod one A1B1, the connecting rod two A2B2, the rotating rod one O2D1, the rotating rod two O2D2, the coil spring one O1C1 and the coil spring two O1C2. First, a pair of active cranks are hingedly connected at the first mounting point O1 on the aircraft frame, namely the crank one O1A1, the crank two O1A2, the crank one O1 A1 and crank two O1A2 are hingedly connected at the first mounting point O1, the lower ends of crank one O1A1 and crank two O1A2 are welded and fixed together, and are hingedly connected to the first mounting point O1 through the fixed connection point; rotating rod one O2D1 and rotating rod two O2D2 are respectively hingedly connected at the second mounting point O2, one end of connecting rod one and connecting rod two are respectively connected to one end of crank one and crank two, and the other ends of connecting rod one and connecting rod two are respectively hingedly connected to the middle parts of rotating rod one O2D1 and rotating rod two O2D2.

[0019] A revolving pair 1 is formed between the fixedly connected crank 1 and crank 2 and the first mounting point O1, a revolving pair 2 is formed between the rotating rod 1 O2D1, the rotating rod 2 O2D2 and the second mounting point O2, a revolving pair 3 is formed between the crank 1 and the connecting rod 1, a revolving pair 4 is formed between the crank 2 and the connecting rod 2, a revolving pair 5 is formed between the connecting rod 1 and the rotating rod 1, and a revolving pair 6 is formed between the connecting rod 2 and the rotating rod 2.

[0020] The first rotating rod and the first mounting point O1 are connected, and the second rotating rod and the second mounting point O2 are connected by a coil spring 1 and a coil spring 2, respectively. The connection points of the coil springs on the first rotating rod O2D1 and the second rotating rod O2D2 are C1 and C2, respectively. The connection points C1 and C2 are between the B1 point and the D1 point on the first rotating rod O2D1 and between the B2 point and the D2 point on the second rotating rod O2D2;

[0021] The materials of the crank one O1A1, the crank two O1A2, the connecting rod one A1B1, the connecting rod two A2B2, the rotating rod one O2D1 and the rotating rod two O2D2 are all made of carbon fiber composite materials, which are light in weight and are conducive to reducing the load.

[0022] When the transmission mechanism is pre-assembled in the initial state, the angle between the pair of connecting rods is smaller than the angle between the pair of active cranks, the upper end of the spring is connected to the upper part of the rotating rod near the upper end, and the structure is stable and reliable.

[0023] The angle between the fixedly connected crank 1 and crank 2 is β, the length of crank 1 and crank 2 is equal to a, the length of rocker 1 and rocker 2 is equal to b, the length of connecting rod O2B1 and connecting rod O2B2 is equal to c, the distance between frame 1 and frame 2 is d, arc D1E1 and arc D2E2 are the trajectories of the rocker ends D1 and D2 during the flapping process, the dotted lines O2E1 and O2E2 are the lower limit positions of the rockers O2D1 and O2D2 during the flapping process, the solid lines O2D1 and O2D2 are the upper limit positions of the rockers during the flapping process, and the angle φ between the two limit positions is the flapping angle. The lengths of each rod of the single crank double rocker mechanism meet the following conditions:

[0024]

[0025]

[0026]

[0027] The single-crank flapping-wing aircraft transmission mechanism of the present invention imitates the internal structure of the existing biological thorax through a pair of active cranks, connecting rods, rotating rods and springs, and adds elastic elements inside the structure. The elastic elements are used to store and release energy to alleviate the problem of excessive energy loss in the transmission mechanism, reduce energy waste, and increase flight time. The structure is simple and the energy loss during operation is small. When a=7mm, b=38mm, c=16mm, d=39mm, φ=51°, β=30°, the single-crank elastic flapping-wing aircraft transmission mechanism of the present invention can effectively reduce the power peak by 40.3% compared with a traditional mechanism without a spring.

[0028] Specific design ideas:

[0029] Flapping-wing aircraft is an aircraft developed based on the bionic principles of biological flight. It has incomparable advantages over traditional fixed-wing and rotorcraft. It can integrate lifting, hovering, and propulsion systems into a pair of wings to achieve flight. It has very good maneuverability and stability during flight and has a wide range of uses in both civilian and military fields.

[0030] The existing flapping-wing aircraft mainly include bird-like and insect-like types. The insect-like type mainly adopts new transmission mechanisms such as piezoelectric drive, while the slightly larger bird-like flapping-wing aircraft adopts traditional single crank or double crank mechanism to realize the flapping of wings on both sides. Although the single crank mechanism has a small space size, there is always a phase difference between the two sides of the wing surface, which will affect the stability of control. Although the two sides of the double rocker mechanism are always symmetrical, due to structural reasons, the space size is large and it is difficult to miniaturize.

[0031] At present, due to the limitation of load, the battery energy carried by flapping-wing aircraft cannot meet the demand of long-term flight, mainly because the energy conversion efficiency of the transmission mechanism is not high, while the energy loss in the body of natural organisms is very small due to the existence of muscle tissue, etc. Therefore, we can imitate the internal structure of the existing biological chest cavity, add elastic elements inside the structure, and use the elastic elements to store and release energy to alleviate the problem of excessive energy loss in the transmission mechanism, reduce energy waste, and increase flight time.

[0032] In order to solve the shortcomings of traditional flapping-wing aircraft transmission mechanisms, such as large space dimensions and difficulty in miniaturization, and to improve the energy conversion efficiency of the transmission mechanism, the present invention proposes a single-crank elastic flapping-wing aircraft transmission mechanism with a simple structure and low energy loss during operation.

[0033] Figure 1 This is a simplified diagram of the design of a single-crank elastic flapping-wing aircraft transmission mechanism. A pair of crank-rocker mechanisms is used, in which the two cranks are fixedly connected together at the ends by fixed welding, and there is always a fixed angle β between the two cranks during operation.

[0034] O1C1 and O1C2 are connected by a spring. During the operation of the flapping mechanism, the stiffness of the spring and the positions of the spring ends C1 and C2 need to be determined according to the size of the crank-connecting rod mechanism and the load applied to the connecting rod to achieve optimal energy saving.

[0035] In order to achieve the best symmetry of the rockers on both sides of the transmission mechanism of the flapping-wing aircraft, the calculation formula for the length of each rod of the crank rocker mechanism is as follows:

[0036]

[0037]

[0038]

[0039] When a=7mm, b=38mm, c=16mm, d=39mm, φ=51°, and β=30°, the single-crank elastic flapping-wing aircraft transmission mechanism can effectively reduce the power peak by 40.3% compared to the case where no spring is installed.

Claims

1. A single crank flapping wing aircraft transmission mechanism, characterized in that: The invention comprises a pair of fixedly connected active cranks, the pair of active cranks are symmetrically arranged in a V shape, the lower ends are fixedly combined, and the combining point is hingedly connected to a first mounting point on the aircraft frame, the upper ends of the pair of active cranks are connected to a pair of connecting rods of equal length and symmetrically arranged, the lower ends of the connecting rods are hingedly connected to the upper ends of the active cranks, the upper ends of the connecting rods are hingedly connected to the middle parts of a pair of rotating rods, the lower ends of the pair of rotating rods are hingedly connected to a second mounting point on the aircraft frame, the pair of rotating rods are equal in length and symmetrically arranged along the second mounting point, a spring is fixedly connected to the upper section of each side of the rotating rod, the upper end of the spring is fixedly connected to the rotating rod, and the lower end is fixedly connected to the first mounting point; In the initial state of the transmission mechanism, the angle between the pair of connecting rods is smaller than the angle between the pair of active cranks; the upper end of the spring is connected to the upper part of the rotating rod near the upper end; the length a of the active crank, the length b of the rotating rod, the angle β between the length c of the connecting rod and the pair of active cranks, the distance d between the first mounting point and the second mounting point, the flapping angle between the upper limit position and the lower limit position of the rotating rod The calculation formula is:

2. The single crank flapping wing aircraft transmission mechanism according to claim 1, characterized in that: The active crank, connecting rod and rotating rod are made of carbon fiber composite materials.

3. The single crank flapping wing aircraft transmission mechanism according to claim 1, characterized in that: The spring is a coil spring.

4. The single crank flapping wing aircraft transmission mechanism according to claim 3, characterized in that: The d=39mm, When β=30°, a=7mm, b=38mm, c=16mm.

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