CN113002766B - Variable-pitch multi-rotor unmanned aerial vehicle with noise reduction function by adopting scissor type blades - Google Patents

Abstract

The invention discloses a variable-pitch multi-rotor unmanned aerial vehicle using scissor blades for noise reduction, comprising a frame, a power transmission system, a variable-pitch rotor system and a flight control system; the power transmission system includes a motor and a first pulley , a second pulley, a transmission belt, a synchronous pulley and an auxiliary shaft; the pitch rotor system has four groups, which are distributed at the end of the frame; and each group of pitch rotor systems includes a main shaft, a first rocker arm, a first The connecting rod, the second rocker arm, the second connecting rod, the slider pitch change ring and the propeller hub. The invention discloses a variable-pitch multi-rotor UAV with noise reduction using scissor blades. The power transmission system uses a motor as power output, and adopts a belt transmission mode. The transmission terminal is connected to the variable-pitch rotor system, and the side multi-link mechanism The first rocker arm is connected to the output end of the steering gear. The flight control system controls the output of the steering gear to change the collective pitch of the blades through a multi-link mechanism, and quickly and accurately controls the change of lift by changing the pitch to change the flight attitude.

Description

A variable-pitch multi-rotor drone with noise reduction using scissor blades

technical field

The invention relates to the technical field of unmanned aerial vehicles, in particular to a variable-pitch multi-rotor unmanned aerial vehicle that adopts scissor-type blades for noise reduction.

Background technique

At present, the attitude control of the quadrotor aircraft mainly adopts the method of changing the rotation speed of the blades, and it is mainly divided into odd-numbered axes and even-numbered axes. Due to the control method of variable rotation speed, fixed-pitch blades are used on the axes. By changing the relative rotational speed of the four blades, the aircraft can achieve take-off, forward flight and hovering flight states.

However, the existing quadrotors have the following disadvantages:

First, the flight control system is complex: the speed change requires a long response time, and there will also be a relatively obvious overshoot during the adjustment process, and it will recover after deviating from the target flight state, so it is necessary to complete the accurate flight attitude under the same flight conditions. Regulation requires a very complex flight control program and the protection of hardware such as high-precision motors;

Second, the carrying capacity is limited: due to the use of fixed-pitch blades, it can only guarantee the optimal lift in a certain flight state. When it deviates from this state, the lift will decrease and affect normal flight. Large load capacity can only increase the number of rotors, and at the same time, it will increase the weight of the structure, reduce the increase in the load capacity, and eventually reach a saturation point where the load capacity cannot break through the limit;

Third, the flight attitude is limited: the fixed-pitch blade only maintains the best efficiency under one working condition. When its attitude changes greatly (the inclination angle is close to 90 degrees), the lift of the propeller is not enough to stabilize the attitude. Therefore, the existing quadrotor can only complete the stable attitude flight under the condition of forward flight and small inclination angle, and cannot complete the continuous sideways flight or even the reverse flight;

Fourth, the utilization rate of the motor is not high. Due to the need to change the attitude of the speed control, the motor must ensure that the power is sufficient to complete such control. Therefore, in the working state, the power of the motor cannot be fully utilized, and the use efficiency is limited.

Fifth, in the existing variable-pitch multi-rotor aircraft, due to the different working conditions of the variable-pitch blade and the fixed-pitch blade, the variable-pitch blade can achieve the optimal blade efficiency under various working conditions, so that the As a result, under the same load, compared with the optimal fixed-pitch blade for a specific working condition, the rotating speed is larger, and its basic noise is larger than that of the ordinary quadrotor.

Therefore, how to provide a variable-pitch multi-rotor UAV with less noise is an urgent problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a variable-pitch multi-rotor UAV with noise reduction using scissor blades, which solves at least one of the above technical problems.

In order to achieve the above purpose, the present invention adopts the following technical solutions: a variable-pitch multi-rotor unmanned aerial vehicle using scissor-type blades for noise reduction, including a frame, a power transmission system, a variable-pitch rotor system and a flight control system, so The frame is "H" type;

The power transmission system includes a motor, a first pulley, a second pulley, a transmission belt, a synchronous pulley and an auxiliary shaft, the motor is fixed on the frame, and the output shaft is fixedly connected with the first pulley and the auxiliary shaft. the second pulley; the first pulley and the second pulley are connected through the auxiliary shaft;

The pitch rotor system has four groups, which are distributed at the end of the frame; and each group of the pitch rotor system includes a main shaft, a first rocker arm, a first link, a second rocker arm, a first rocker arm, and a second rocker arm. Two connecting rods, a slider pitch-changing ring and a propeller hub, the synchronous pulley is fixedly installed on the main shaft, one end of the first rocker arm is connected to the flight control system, and the other end is connected to the first connecting rod ; the other end of the first connecting rod is movably connected to the second rocker arm; the other end of the second rocker arm is connected to the slider variable ring; and the slider variable ring is sleeved on the the outer circumference of the main shaft; the propeller hub is fastened to the end of the main shaft; the propeller blades are fixed at both ends of the propeller hub; the other end of the slider pitch variable ring is connected with a V-shaped transmission seat, and the V-shaped transmission seat is The two outwardly extending lugs of the propeller hub are hinged through the second connecting rod which is centrally symmetric.

The variable-pitch multi-rotor unmanned aerial vehicle disclosed by the invention adopts the noise reduction of scissor blades, and the power transmission system uses the motor as the power output, and the output power of the motor is the optimal power in the normal state, and the output power is kept constant. The belt transmission mode is adopted, the transmission terminal is connected to the variable pitch rotor system, the first rocker arm, the first link, the second rocker arm and the second link are used on the side, and the flight control system controls the output of the steering gear to change the collective pitch of the blades. In this way, the output power of the motor can not be changed, and the change of the lift can be quickly and accurately controlled by changing the pitch to change the flight attitude; the motor maintains a constant optimal power output to avoid the problem of low motor power surplus utilization. At the same time, the pitch system can be enlarged according to the situation, the lift range can be effectively adjusted, and the load capacity can be effectively increased.

Preferably, each group of the variable-pitch rotor systems includes two upper and lower paddle discs, and the two paddle discs are arranged in a scissor angle.

The beneficial effect of adopting the above technical solution is that the use of the upper and lower paddle discs can ensure relatively larger lift and payload, and the angle between the upper and lower pairs of paddles in the top-down plane is the scissors angle. Because of the scissor angle arrangement, each paddle has a natural frequency modulation, which redistributes the energy of the aerodynamic noise of the paddle, and turns the high-frequency noise into a wide-band wide-area noise, so as to achieve the purpose of noise reduction.

Preferably, the included angle of the blades of the two paddle discs is 35°-55°.

The beneficial effect of adopting the above technical solution is that the arrangement with the included angle of 35°-55° ensures the optimal combination of lift efficiency and noise reduction of the two paddle discs.

Preferably, the descending paddle disc is at the front, and the ascending paddle disc is at the rear.

The beneficial effect of adopting the above technical solution is that the upper and lower paddle discs are arranged in an "L" shape, that is, the descending paddle disc is in front and the upward paddle disc is behind, and at the same time, the distance between the paddle discs can be adjusted, which can reduce the number of paddles between the two paddle discs. Vortex interference, suppress the generation of vortex-induced noise, and at the same time properly improve the lift efficiency.

Preferably, the two sets of motors are connected by electronic synchronizers.

The beneficial effect of adopting the above technical solution is that the electronic synchronizer is used to ensure that the output powers of the two are consistent.

It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a variable-pitch multi-rotor UAV with noise reduction using scissor blades, which can quickly and accurately control the lift change by changing the pitch. Change the flight attitude; the variable pitch blades can ensure that the angle of attack of the blades is negative when the aircraft is flying backwards, and the pulling force is upward, thus ensuring the stable flight of the aircraft; the motor maintains a constant and optimal power output, thereby avoiding the occurrence of motor power surplus and inefficient utilization. At the same time, the variable pitch system can be enlarged according to the situation, the lift range can be effectively adjusted, and the load capacity can be effectively increased; in order to ensure effective lift efficiency and noise reduction characteristics, the upper and lower double paddle discs are arranged, and the angle between the scissors is used. The arrangement is 35°-55° to ensure the optimal lift efficiency and noise reduction performance of the two propeller discs.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

Figure 1 is a schematic diagram of the structure provided by the present invention.

FIG. 2 is a schematic structural diagram of the pitch rotor system at position A provided by the present invention.

3 is a schematic structural diagram of the power transmission system at B provided by the present invention.

Among them, each reference sign is:

1-frame, 2-power transmission system, 3-pitch rotor system, 4-flight control system, 21-motor, 22-first pulley, 23-second pulley, 24-drive belt, 25-timing belt Wheel, 26-auxiliary shaft, 31-main shaft, 32-first rocker arm, 33-first link, 34-second rocker arm, 35-second link, 36-slider pitch control ring, 37-paddle Hub, 38-Blade, 39-V Drive Seat.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in Figures 1-2, an embodiment of the present invention discloses a variable-pitch multi-rotor UAV with noise reduction using scissor blades, including a frame 1, a power transmission system 2, a variable-pitch rotor system 3 and Flight control system 4, frame 1 is "H" type.

The power transmission system 2 includes two groups, a first pulley 22, a second pulley 23, a transmission belt 24, a synchronous pulley 25 and an auxiliary shaft 26, and the two groups of motors 21 are connected by an electronic synchronizer, which ensures the output power of the two motors Consistent, the output power of the motor is the optimal power in the normal state, and the output power is kept constant. The motor 21 is fixed on the frame 1, and its output shaft is fixedly connected with a first pulley 22 and a second pulley 23; the first pulley 22 and the second pulley 23 are connected through an auxiliary shaft 26; the pitch rotor system 3 There are four groups, which are distributed at the end of the frame 1; and each group of pitch rotor systems 3 includes a main shaft 31, a first rocker arm 32, a first link 33, a second rocker arm 34, a second link 35, The slider pitch variable ring 36 and the propeller hub 37, the synchronous pulley 25 is fixedly installed on the main shaft 31, one end of the first rocker arm 32 is connected to the flight control system 4, and the other end is connected to the first connecting rod 33; The other end is movably connected to the second rocker arm 34; the other end of the second rocker arm 34 is connected to the slider pitch change ring 36; and the slider pitch change ring 36 is sleeved on the outer circumference of the main shaft 31; At the end; the two ends of the propeller hub 37 are fixed with blades 38; the other end of the slider pitch change ring 36 is connected with a V-shaped transmission seat 39, and the V-shaped transmission seat 39 and the two lugs extending outward from the propeller hub 37 The articulation is carried out by the second link 35 which is centrally symmetrical.

The motor 21 drives the first pulley 21 to rotate, and transmits the rotation to the synchronous pulley 25 through the meshed belt. The synchronous pulley 25 drives the rotor system 3 to rotate. The drive belt 24 transmits the rotation to another set of pulleys in parallel therewith.

The UAV has four sets of pitch rotor systems 3, each set of pitch rotor systems 3 includes two upper and lower paddles, and the steering is the same; the adjacent two sets of rotors have opposite directions. The different turning directions are realized by the different ways of torsion of the transmission belt between the power input first pulley 21, the second pulley 23 and the timing pulley 25. The purpose is to offset the reaction torque generated by the rotation of each group of rotors and affect the aircraft's performance. stability. And the included angle of the blades of the two paddle discs is an acute angle. The upper and lower paddles of each group of rotors are each driven by a steering gear to achieve pitch change, and the two steering gears of each rotor system drive the first rocker arm 32 to rotate at the same angle, so that the upper and lower paddles change the same pitch .

The flight control system 4, that is, the steering gear controls the first rocker arm 32 to rotate in the horizontal plane, and drives the second rocker arm 34 connected with the first link 33 to rotate in the vertical plane. The displacement of the two rocker arms 34 moves up and down along the main shaft 31 . The V-shaped transmission seat connected with the slider pitch variable ring 36 and the two outwardly extending lugs of the propeller hub 37 connected to the end of the main shaft 31 are hinged through the center-symmetric second connecting rod 35; the steering gear is controlled by the slider. The vertical movement of the pitch ring 36 indirectly controls the pitch of the blades, and finally realizes the control of the lift and torque of the rotor.

As shown in Figure 2, the blades of the two propellers are arranged in a scissors angle. The traditionally arranged pitch system has the characteristics of high noise. By changing the scissor angles of the two blades, the natural frequency modulation that occurs will reduce the aerodynamic noise of the propellers. The energy redistribution is to convert high-frequency noise into broadband wide-area noise to achieve noise reduction.

To determine the optimal scissor angle, the following experiments were designed and implemented:

In the hovering state of the variable-pitch quadrotor, there is a certain speed and a certain pitch, change the scissor angle, and measure the noise and tension of different scissor angles in this state, the measurement range is 0-90 °, the measurement division is 5°. According to the experimental data, it is shown that when the scissor angle is set at 35-55°, the lift efficiency and noise reduction can achieve the best match. Therefore, the included angle of the scissor angle of the blade is 35°-55°.

The down paddle is in the front and the up paddle is in the back. At the same time, the pitch of the paddle discs is adjusted to reduce the paddle vortex interference of the two paddle discs, suppress the noise generated by the redundant vortexes, and at the same time appropriately improve the lift efficiency.

Among them, the blades 38 are variable-pitch blades, and the variable-pitch blades can ensure that the angle of attack of the blades is negative and the pulling force is upward when the aircraft is flying upside down, thereby ensuring the stability of the aircraft.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (4)

1. A variable-pitch multi-rotor unmanned aerial vehicle adopting scissor blades to reduce noise is characterized by comprising a frame (1), a power transmission system (2), a variable-pitch rotor system (3) and a flight control system (4),

the rack (1) is H-shaped;

the power transmission system (2) comprises two groups, each group comprises a motor (21), a first belt pulley (22), a second belt pulley (23), a transmission belt (24), a synchronous belt pulley (25) and an auxiliary shaft (26), the motor (21) is fixed on the rack (1), and an output shaft of the motor is fixedly connected with the first belt pulley (22) and the second belt pulley (23); the first belt pulley (22) and the second belt pulley (23) are connected through the auxiliary shaft (26);

the variable-pitch rotor system (3) is provided with four groups and is distributed at the end part of the rack (1) in an H shape; each group of the variable-pitch rotor systems (3) comprises a spindle (31), a first rocker arm (32), a first connecting rod (33), a second rocker arm (34), a second connecting rod (35), a slider variable-pitch ring (36) and a hub (37), the synchronous belt wheel (25) is fixedly mounted on the spindle (31), one end of the first rocker arm (32) is connected with the flight control system (4), and the other end of the first rocker arm is connected with the first connecting rod (33); the other end of the first connecting rod (33) is movably connected with the second rocker arm (34); the other end of the second rocker arm (34) is connected with the sliding block variable pitch ring (36); the sliding block variable-pitch ring (36) is sleeved on the periphery of the main shaft (31); the hub (37) is fastened to the end of the main shaft (31); blades (38) are fixed at two ends of the propeller hub (37); the other end of the sliding block variable-pitch ring (36) is connected with a V-shaped transmission seat (39), and the V-shaped transmission seat (39) is hinged with two lugs extending outwards from the propeller hub (37) through the second connecting rod (35) with central symmetry;

each group of the variable-pitch rotor systems (3) also comprises an upper paddle disk and a lower paddle disk, and the included angle of the two paddle disks is an acute angle and is arranged in a scissor angle; two oar dishes about adopting can guarantee bigger lift and payload relatively, overlook the contained angle between two pairs of paddles about in the plane and be the scissors angle, through setting up the scissors angle, two oar dishes are because the scissors angle arranges and natural frequency modulation appears, make the energy of oar dish aerodynamic noise redistribute, become the wide band wide area noise with high frequency noise to reach the purpose of making an uproar falls.

2. A pitch controlled multi-rotor drone with noise reduction by means of scissor blades according to claim 1, characterized in that said acute angle is 35 ° -55 °.

3. The variable pitch multi-rotor drone with noise reduction by scissor blades according to claim 1, wherein the down going paddle tray is forward and the up going paddle tray is aft.

4. A pitch-controlled multi-rotor drone with noise reduction by means of scissor blades according to claim 1, characterized in that the two sets of motors (21) are connected by means of electronic synchronizers.

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