CN118182831A - Circulation variable-pitch flapping wing mechanism and application thereof - Google Patents

Abstract

The present invention relates to a cyclic variable pitch flapping wing mechanism and its application. The cyclic variable pitch flapping wing mechanism comprises a central axis, a rotary arm, an eccentric shaft, flapping wings and a variable pitch connecting rod. The rotary arm is rotatably sleeved on the central axis. A plurality of force arms are arranged in a circular array around the rotary arm with the central axis as the center. The eccentric shaft is fixed to one end of the central axis. The axis of the eccentric shaft is parallel to the axis of the central axis and is not colinear. The end of the force arm away from the central axis is rotatably provided with flapping wings. The eccentric shaft is provided with variable pitch connecting rods corresponding to the flapping wings one by one. One end of the variable pitch connecting rod is rotatably connected to the eccentric shaft, and the other end of the variable pitch connecting rod is rotatably connected to the corresponding flapping wing. The beneficial effects of the present invention are: while realizing the cyclic variable pitch control of multi-faceted flapping wings, it has higher aerodynamic efficiency and control flexibility, low structural material requirements and strong noise control capability.

Description

A cyclic variable pitch flapping wing mechanism and its application

Technical Field

The invention relates to the technical field of power devices, and in particular to a cyclic variable pitch flapping wing mechanism and applications thereof.

Background technique

In the existing open aircraft lift devices, the structures that can generate lift include rotors, propellers, flapping wings and rolling wings (cycloidal propellers), etc. The rotors, propellers and rolling wings generate lift in the same principle, mainly through a small angle of attack to generate a force perpendicular to the direction of motion to form thrust, but most of the power is used to push the air to rotate ineffectively or friction consumption, resulting in a small range of effective thrust generation. For example, the existing rolling wing can only generate effective thrust within about 1/2 of the circular motion trajectory. Therefore, compared with the flapping wing mechanism, the existing rotors, propellers and rolling wing mechanisms have low aerodynamic efficiency and high noise. The existing flapping wing structure includes a reciprocating motion mechanism, a folding wing surface, and a flexible wing surface, which has high momentum loss and is prone to structural fatigue. In addition, multiple flapping wings require multiple reciprocating motion mechanisms for control. The overall structure is relatively complex and bulky, and is not suitable for large or heavy aircraft.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a cyclic variable pitch flapping wing mechanism and its application, which can realize cyclic variable pitch control of multi-surface flapping wings while having higher aerodynamic efficiency and control flexibility, low structural material requirements and strong noise control capabilities.

The purpose of the present invention is achieved through the following technical solutions:

A cyclic variable pitch flapping wing mechanism comprises a central shaft, a rotary arm, an eccentric shaft, flapping wings and a variable pitch connecting rod. The rotary arm is rotatably sleeved on the central shaft, and a plurality of force arms are arranged in a circular array around the rotary arm with the central shaft as the center. The eccentric shaft is fixed to one end of the central shaft, and the axis of the eccentric shaft is parallel to and not colinear with the axis of the central shaft. A flapping wing is rotatably provided at one end of the force arm away from the central shaft, and a variable pitch connecting rod corresponding to the flapping wing is provided on the eccentric shaft, and one end of the variable pitch connecting rod is rotatably connected to the eccentric shaft, and the other end of the variable pitch connecting rod is rotatably connected to the corresponding flapping wing.

Furthermore, a center disk is fixed on one end of the center shaft, and the eccentric shaft is fixed on the center disk.

Furthermore, a base is rotatably provided at one end of the lever arm away from the central axis, the flapping wing is fixed on the base, and the variable pitch connecting rod is rotatably connected to the base.

Furthermore, the optimal working efficiency of the cyclic variable pitch flapping mechanism satisfies the formulas 0.9<(L ₁ +L ₄ )/(L ₂ +L ₃ )<1, 0.95<(L ₃ +L ₄ )/L ₁ <1.1 and L ₂ /L ₁ <0.35, where L ₁ is the distance between the rotation center of the base on the lever arm and the axis centerline of the central axis, L ₂ is the distance between the rotation center of the base on the lever arm and the rotation center of the variable pitch connecting rod on the base, L ₃ is the distance between the rotation centers of the two ends of the variable pitch connecting rod, and L ₄ is the distance between the axis centerline of the eccentric shaft and the axis centerline of the central axis.

Furthermore, the present invention provides an application of the above-mentioned cyclic variable pitch flapping wing mechanism on an aircraft, wherein a plurality of cyclic variable pitch flapping wing mechanisms are provided on both sides of the aircraft along the flight direction of the aircraft, the centerline of the central axis of the cyclic variable pitch flapping wing mechanism is parallel to the flight direction of the aircraft, the plurality of cyclic variable pitch flapping wing mechanisms on both sides of the aircraft correspond one to one, and the corresponding two cyclic variable pitch flapping wing mechanisms are symmetrically arranged on both sides of the aircraft and the rotation directions of the swing arms are opposite.

Furthermore, the present invention also provides another application of the above-mentioned cyclic variable pitch flapping wing mechanism on an aircraft, wherein multiple cyclic variable pitch flapping wing mechanisms are provided on both sides of the aircraft along the flight direction of the aircraft, the centerline of the central axis of the cyclic variable pitch flapping wing mechanism is perpendicular to the flight direction of the aircraft, the multiple cyclic variable pitch flapping wing mechanisms on both sides of the aircraft correspond one to one, and the corresponding two cyclic variable pitch flapping wing mechanisms are symmetrically arranged on both sides of the aircraft and the rotation direction of the spiral arms is the same.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention replaces the crank rocker mechanism of ordinary bionic flapping wings with a double crank connecting rod structure, thereby realizing cyclic variable pitch control of multi-faceted flapping wings, and at the same time combining the high efficiency of flapping wings and the control flexibility of variable pitch rotors. It is more efficient, quieter and more flexible than bionic flapping wings, traditional rotors, rolling wings (cycloidal propellers) and other structural designs.

2. The present invention eliminates the reciprocating motion mechanism, folding wing surface, and flexible wing surface in the conventional bionic flapping wing structure. The overall structure has less momentum loss, is not prone to fatigue, is simple and reliable, has low requirements on the material of the flapping wing, and can meet the needs of large-scale and heavy-duty aircraft.

3. The present invention optimizes the design of relevant dimensional parameters of the cyclic variable pitch flapping wing mechanism through simulation, so that the overall structure can achieve optimal working efficiency, realize the positive excitation of vortices generated by multi-faceted flapping wings, and provide additional thrust or reduce resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of the overall structure of the present invention;

FIG2 is a front view schematic diagram of the structural state of the cyclic variable pitch flapping wing mechanism of the present invention when generating maximum thrust;

FIG3 is a schematic diagram of an application state of the cyclic variable pitch flapping wing mechanism of the present invention on an aircraft;

FIG. 4 is a schematic diagram of another application state of the cyclic variable pitch flapping wing mechanism in the present invention on an aircraft.

In the figure: 1. Central axis; 2. Swing arm; 3. Eccentric axis; 4. Flapping wing; 5. Pitch-changing connecting rod; 6. Lever arm; 7. Central disk; 8. Base.

Detailed ways

The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

As shown in FIG1 , a cyclic variable pitch flapping wing mechanism includes a central shaft 1 , a rotary arm 2 , an eccentric shaft 3 , flapping wings 4 and a variable pitch connecting rod 5 . Specifically, the swing arm 2 is rotatably sleeved on the central axis 1; a plurality of force arms 6 are arranged in a circular array around the swing arm 2 with the central axis 1 as the center, and the force arms 6 and the swing arm 2 can be integrally formed; a central disk 7 is fixed at one end of the central axis 1, and the eccentric shaft 3 is fixed on the central disk 7, and the central axis 1, the central disk 7 and the eccentric shaft 3 can be integrally formed, wherein the central disk 7 can be replaced by a crankshaft, a bent rod or other structures, and it is only necessary to ensure that the axis line of the eccentric shaft 3 is parallel to the axis line of the central axis 1 and is not colinear; a base 8 is provided at the end of the force arm 6 away from the central axis 1, and the base 8 can be rotatably connected to the force arm 6 by a connecting member such as a rotating shaft, and the rotation centers of the plurality of bases 8 on the force arm 6 are located on the same circumference, and the flapping wings 4 can be fixed to the base 8 by connecting members such as bolts, and a variable pitch connecting rod 5 corresponding to the flapping wings 4 is provided on the eccentric shaft 3, one end of the variable pitch connecting rod 5 is rotatably connected to the eccentric shaft 3 by a sleeve connection or the like, and the other end of the variable pitch connecting rod 5 is rotatably connected to the corresponding base 8 by a sleeve connection or the like.

Based on the above structure, the present invention forms a double crank connecting rod structure through the force arm 6, the base 8, the eccentric shaft 3, the pitch-changing connecting rod 5 and the central shaft 1, and replaces the crank rocker mechanism of the ordinary bionic flapping wing with the double crank connecting rod structure, so as to realize the cyclic pitch-changing control of the multi-faceted flapping wing 4. Specifically, the swing arm 2 is driven by a power device such as an engine to rotate with the axis of the central shaft 1 as the rotation center, and then drives multiple flapping wings 4 to revolve with the axis of the central shaft 1 as the rotation center at the same time. In the process of the swing arm 2 driving the flapping wing 4 to rotate, the eccentric shaft 3 controls the rotation of the base 8 through the pitch-changing connecting rod 5, and then adjusts the wing surface angle of attack of the flapping wing 4 (that is, the angle between the wing surface of the flapping wing 4 and the direction of movement) during the revolution of the flapping wing 4, so that the flapping wing 4 interacts with the air to generate thrust (or lift).

When installing the above-mentioned cyclic variable pitch flapping wing mechanism, the present invention can achieve positive and reverse installation by adjusting the position of the connection point between the variable pitch connecting rod 5 and the base 8 relative to the movement direction of the force arm 6, and has the same lift effect, wherein the connection point between the variable pitch connecting rod 5 and the base 8 is after the movement direction of the force arm 6 for positive installation, and the connection point between the variable pitch connecting rod 5 and the base 8 is before the movement direction of the force arm 6 for reverse installation. Lift can be generated in different directions through positive and reverse installation, and different installation methods are adopted according to actual needs during use. When the present invention is in operation, the position of the eccentric shaft 3 can be changed by rotating the central shaft 1, thereby realizing vector control of the thrust (or lift) direction.

As shown in Fig. 1 and Fig. 2, in this embodiment, the cyclic variable pitch flapping wing mechanism is equipped with four flapping wings 4, the swing arm 2 rotates in the counterclockwise direction, and the connection point between the variable pitch connecting rod 5 and the base 8 is located behind the movement direction of the corresponding force arm 6 (i.e., it is installed in the forward direction). During the rotation of the swing arm 2, the wing surface angle of attack of the four flapping wings 4 changes cyclically under the drive of the variable pitch connecting rod 5. In the structural state shown in Fig. 2, the position of each force arm 6 is numbered in sequence according to the rotation direction of the swing arm 2, taking the force arm 6 corresponding to the center line of the eccentric shaft 3 as the reference. The wing surface angle of attack of flapping wing 4 at position 1 is close to 0, and the wing surface resistance is small; the wing surface angle of attack of flapping wing 4 at position 2 is smaller, and flapping wing 4 generates partial lift and partial lateral thrust, wherein the lateral thrust can be used to control the yaw or roll of the aircraft; the wing surface of flapping wing 4 at position 3 is nearly perpendicular to the tangential direction of the revolution of flapping wing 4, and the wing surface angle of attack of flapping wing 4 at this position is the largest, and flapping wing 4 generates thrust and the thrust is the largest; flapping wing 4 at position 4 generates wing surface resistance, but the duration is short, and at this time, due to the adjustment effect of variable pitch connecting rod 5, the angular velocity of the wing surface of flapping wing 4 rotating counterclockwise relative to the swing arm 2 is the largest, and the overall wing surface resistance is small.

As the swing arm 2 rotates, the positions of the above four force arms 6 are cyclically alternated, wherein during the movement of the flapping wing 4 at position 1 to position 4, the variable pitch connecting rod 5 drives the flapping wing 4 to rotate, and the flapping wing 4 will gradually transition from generating resistance to generating lift, and then the lift reaches a maximum, and finally gradually transitions to generating resistance, and the forces generated by the flapping wings 4 at other positions change accordingly, so the flapping wing 4 can continuously generate downward thrust and partial lateral thrust from position 1 to position 4 during the rotation of the swing arm 2 for one circle. Based on this, the cyclic variable pitch flapping wing mechanism of the present invention can generate effective thrust within the range of nearly 3/4 of the circular trajectory of the swing arm 2 during the rotation of the swing arm 2 for one circle, and compared with the existing rolling wings that can only generate effective thrust within the range of about 1/2 of the circular motion trajectory, the cyclic variable pitch flapping wing mechanism of the present invention has a higher power conversion rate.

In traditional lift devices such as rotors, propellers, and rollers (cycloidal propellers), when the angle of attack is ∠α and the wing resistance is N, the maximum component converted into thrust in theory does not exceed N*tan∠α (the tangent component of the wing resistance perpendicular to the direction of movement. In order to prevent the wing from stalling, ∠α is usually less than 30 degrees or lower, so the effective thrust component is usually less than 0.5N), and the remaining larger part is used to promote the ineffective rotation of the air or friction consumption, and generate rotating airflow and horizontal torque (single-propeller helicopters use the tail rotor to offset excess torque). In this regard, the cyclic variable pitch flapping wing mechanism of the present invention adopts the flapping wing principle, and its operating trajectory and angle of attack changes in the lift range are similar to the flapping wing trajectory of natural birds. In the large angle of attack operating range (such as near position 3 mentioned above), the wing surface resistance is almost completely converted into thrust (because the wing surface resistance is opposite to the direction of movement, the wing surface resistance is the thrust of the present invention), so that the cyclic variable pitch flapping wing mechanism of the present invention generates less invalid rotating wake during operation, generates less noise, and greatly improves the aerodynamic efficiency compared with traditional rotors, propellers, rollers (cycloidal propellers) and other small angle of attack operating mechanisms.

In order to obtain the optimal working efficiency of the cyclic variable pitch flapping wing mechanism, the present invention optimizes the relevant parameters of the cyclic variable pitch flapping wing mechanism through simulation and scaled model test. When the following formula is met, the cyclic variable pitch flapping wing mechanism can achieve the optimal working efficiency:

0.9<(L ₁ +L ₄ )/(L ₂ +L ₃ )<1;

0.95<(L ₃ +L ₄ )/L ₁ <1.1;

_L2 / _L1 <0.35.

In the formula, _L1 is the distance between the rotation center of the base 8 on the lever arm 6 and the axis line of the central axis 1, _L2 is the distance between the rotation center of the base 8 on the lever arm 6 and the rotation center of the variable pitch connecting rod 5 on the base 8, _L3 is the distance between the rotation centers at both ends of the variable pitch connecting rod 5, and _L4 is the distance between the axis line of the eccentric shaft 3 and the axis line of the central axis 1.

The optimized cyclic variable pitch flapping wing mechanism can achieve the maximum thrust (lift) generated by the multi-surface flapping wings, and through the rotation speed control of the swing arm, the vortex generated by the flapping wings can be positively excited to provide additional thrust or reduce drag. Compared with traditional flapping wings, it has significant improvements in efficiency, reliability, and scope of application.

When the cyclic variable pitch flapping wing mechanism of the present invention is applied to an aircraft, the layout of the cyclic variable pitch flapping wing mechanism includes parallel layout and axis-to-axis layout.

As shown in Figure 3, when the cyclic variable pitch flapping wing mechanisms are arranged in parallel on the aircraft, multiple cyclic variable pitch flapping wing mechanisms are installed on both sides of the aircraft along the flight direction of the aircraft, and the centerline of the central axis 1 of the cyclic variable pitch flapping wing mechanism is parallel to the flight direction of the aircraft. The multiple cyclic variable pitch flapping wing mechanisms on both sides of the aircraft correspond to each other one by one, and the corresponding two cyclic variable pitch flapping wing mechanisms are symmetrically arranged on both sides of the aircraft and the rotation directions of the swing arms 2 are opposite.

As shown in FIG4 , when the cyclic variable pitch flapping wing mechanism is arranged in an axis-aligned layout on the aircraft, multiple cyclic variable pitch flapping wing mechanisms are arranged on both sides of the aircraft along the flight direction of the aircraft, and the axis line of the central axis 1 of the cyclic variable pitch flapping wing mechanism is perpendicular to the flight direction of the aircraft. The multiple cyclic variable pitch flapping wing mechanisms on both sides of the aircraft correspond to each other one by one, and the corresponding two cyclic variable pitch flapping wing mechanisms are symmetrically arranged on both sides of the aircraft and the rotation direction of the swing arm 2 is the same. The cyclic variable pitch flapping wing mechanisms on the same side of the aircraft rotate in pairs in opposite directions to offset the rotational torque. Under the axis-aligned layout, an aircraft can use only two cyclic variable pitch flapping wing mechanisms symmetrically arranged on both sides of the fuselage, and dynamic balance control is achieved by adjusting the center of gravity position and the rotation speed and torque of the cyclic variable pitch flapping wing mechanism.

The present invention combines the high efficiency of flapping wings with the control flexibility of variable pitch rotors. In addition, since the present invention eliminates the reciprocating motion mechanism, folding wing surface, and flexible wing surface in conventional bionic flapping wing structures, the cyclic variable pitch flapping wing mechanism has less overall momentum loss, is less prone to structural fatigue, is simple and reliable, and can be cyclically controlled with multiple flapping wings, has low requirements for wing surface materials, and can be applied to large-scale and heavy-duty aircraft.

Based on the working principle and application of the above-mentioned cyclic variable pitch flapping wing mechanism, the cyclic variable pitch flapping wing mechanism of the present invention can not only be used in aerospace fields such as aircraft, but also can replace existing vertical axis wind power generation equipment, and can also be used in fields such as wind power generation.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (6)

1. A cyclic variable pitch flapping wing mechanism, characterized in that it comprises a central axis (1), a rotary arm (2), an eccentric shaft (3), a flapping wing (4) and a variable pitch connecting rod (5), wherein the rotary arm (2) is rotatably sleeved on the central axis (1), a plurality of force arms (6) are arranged in a circular array around the rotary arm (2) with the central axis (1) as the center, the eccentric shaft (3) is fixed to one end of the central axis (1), the axis line of the eccentric shaft (3) is parallel to the axis line of the central axis (1) and is not colinear, a flapping wing (4) is rotatably provided at one end of the force arm (6) away from the central axis (1), a variable pitch connecting rod (5) corresponding to the flapping wing (4) is provided on the eccentric shaft (3), one end of the variable pitch connecting rod (5) is rotatably connected to the eccentric shaft (3), and the other end of the variable pitch connecting rod (5) is rotatably connected to the corresponding flapping wing (4). 2. The cyclic variable pitch flapping wing mechanism according to claim 1 is characterized in that a center disk (7) is fixed to one end of the center axis (1), and the eccentric axis (3) is fixed on the center disk (7). 3. The cyclic variable pitch flapping wing mechanism according to claim 1 is characterized in that a base (8) is rotatably provided at one end of the lever arm (6) away from the central axis (1), the flapping wing (4) is fixed on the base (8), and the variable pitch connecting rod (5) is rotatably connected to the base (8). 4. The cyclic variable pitch flapping wing mechanism according to claim 1 is characterized in that the optimal working efficiency of the cyclic variable pitch flapping wing mechanism satisfies the formulas 0.9<( _L1 + _L4 )/( _L2 + _L3 )<1, 0.95<( _L3 + _L4 )/ _L1 <1.1 and _L2 / _L1 <0.35; wherein _L1 is the distance between the rotation center of the base (8) on the lever arm (6) and the axis line of the central axis (1), _L2 is the distance between the rotation center of the base (8) on the lever arm (6) and the rotation center of the variable pitch connecting rod (5) on the base (8), _L3 is the distance between the rotation centers of the two ends of the variable pitch connecting rod (5), and _L4 is the distance between the axis line of the eccentric shaft (3) and the axis line of the central axis (1). 5. An application of a cyclic variable pitch flapping wing mechanism as described in any one of claims 1 to 4 on an aircraft, characterized in that: a plurality of cyclic variable pitch flapping wing mechanisms are provided on both sides of the aircraft along the flight direction of the aircraft, the centerline of the central axis (1) of the cyclic variable pitch flapping wing mechanism is parallel to the flight direction of the aircraft, the plurality of cyclic variable pitch flapping wing mechanisms on both sides of the aircraft correspond one to one, and the corresponding two cyclic variable pitch flapping wing mechanisms are symmetrically arranged on both sides of the aircraft and the rotation directions of the swing arms (2) are opposite. 6. An application of a cyclic variable pitch flapping wing mechanism as described in any one of claims 1 to 4 on an aircraft, characterized in that: a plurality of cyclic variable pitch flapping wing mechanisms are provided on both sides of the aircraft along the flight direction of the aircraft, the centerline of the central axis (1) of the cyclic variable pitch flapping wing mechanism is perpendicular to the flight direction of the aircraft, the plurality of cyclic variable pitch flapping wing mechanisms on both sides of the aircraft correspond one to one, and the corresponding two cyclic variable pitch flapping wing mechanisms are symmetrically arranged on both sides of the aircraft and the rotation direction of the swing arms (2) is the same.