Self-adaptive variable pitch blade and propeller

Abstract

The invention relates to a self-adaptive variable-pitch blade which comprises a skin and a spar with anisotropy, the skin wraps the spar to form the blade, the thickness direction of the spar is arranged in the vertical direction, the width direction of the spar is arranged in the horizontal direction, and the thickness of the end, close to a blade root of the blade, of the spar is larger than the width of the end, close to the blade root, of the spar. When the rotating speed of the blades is changed, the bending moment force borne by the blades is also changed, under the action of the bending-torsion coupling effect, the wing spar can convert the borne bending moment force into torsion force, then the propeller pitch of the blades is promoted to be changed, synchronous change of the propeller pitch and the rotating speed of the blades is achieved, and the influence trends of the propeller pitch and the rotating speed on the flight state are the same; therefore, the flight state of the aircraft can be rapidly adjusted.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to an adaptive variable pitch blade and a propeller. Background Art

[0002] The electric flight unit of most existing aircraft adopts a fixed-pitch aviation propeller structure. Such aircraft can only adjust the flight state of the aircraft (flight state includes but is not limited to flight altitude and flight attitude) by changing the blade speed. For example, when the flight altitude of the aircraft needs to be increased or decreased, it can only be achieved by increasing or decreasing the blade speed. However, in order to ensure the stability of the aircraft during flight, it is necessary to avoid sudden changes in the blade speed during flight as much as possible. Therefore, the above adjustment method has the problem of slow response speed and cannot achieve rapid adjustment of the flight state of the aircraft.

[0003] Therefore, there is an urgent need for an adaptive variable pitch blade and propeller that can quickly adjust the flight state of an aircraft. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an adaptive variable pitch blade, which has an anisotropic wing beam that can produce torsional deformation when subjected to bending moment force, so that the windward angle of the blade can change with the change of rotation speed, thereby improving the response speed when the flight state changes.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An adaptive variable pitch blade, comprising:

[0007] A skin and an anisotropic spar, wherein the skin is wrapped around the outside of the spar to form a blade, the thickness direction of the spar is arranged in the vertical direction, the width direction of the spar is arranged in the horizontal direction, and the thickness of the spar near the root end of the blade is greater than the width.

[0008] Preferably, along the extension direction of the wing spar, the thickness of the wing spar gradually decreases.

[0009] Preferably, it also includes an upper wing beam and a lower wing beam, and the upper wing beam and the lower wing beam are both arranged in an arc shape, the convex side of the upper wing beam is connected to the skin, and the concave side of the upper wing beam is connected to one side of the spar in the thickness direction, the convex side of the lower wing beam is connected to the skin, and the concave side of the lower wing beam is connected to the other side of the spar in the thickness direction.

[0010] Preferably, the geometric centroid of the spar coincides with the quarter chord line of the blade.

[0011] Preferably, the wing spar is made of carbon fiber material.

[0012] Preferably, foam material is filled between the skin and the spar.

[0013] Preferably, the skin is made by three-layer symmetrical carbon fiber laying.

[0014] Also disclosed is a propeller using the above-mentioned adaptive variable pitch blades, including a transmission shaft and a hub, wherein the transmission shaft is connected to a power output device, the input end of the hub is connected to the transmission shaft, and the output end of the hub is connected to the blades, and the hub is an adjustable pitch hub.

[0015] Preferably, it also includes a first connecting member, one end of which is connected to the hub, and the other end of which is connected to the blade, and the first connecting member is made of a flexible composite material so as to rotate with the blade when the pitch of the blade changes.

[0016] Preferably, a second connecting member is further included, which includes a shaft sleeve and a pitch-changing main shaft, a tooth-shaped protrusion is arranged on the side wall of the pitch-changing main shaft, a groove for accommodating the tooth-shaped protrusion is arranged on the inner wall of the shaft sleeve, and a rotation space is arranged between the tooth-shaped protrusion and the groove along the rotation direction of the pitch-changing main shaft, the shaft sleeve is connected to the hub, and the pitch-changing main shaft is connected to the blade.

[0017] Compared with the prior art, the present invention has achieved the following technical effects:

[0018] In the adaptive variable pitch blade disclosed in the present invention, since the wing beam has anisotropy, when the blade rotation speed changes, the bending moment force it is subjected to also changes accordingly. Under the action of the bending-torsion coupling effect, the wing beam can convert the bending moment force it is subjected to into a torsional force. The torsional force takes the geometric centroid of the wing beam extension direction as the torsional center, causes the wing beam to produce torsional deformation, drives the skin to deflect, and further can cause the pitch of the blade to change accordingly, thereby realizing synchronous changes of the pitch and the blade rotation speed. Specifically, when the blade rotation speed increases, the pitch increases synchronously, and when the blade rotation speed decreases, the pitch decreases synchronously. The pitch and rotation speed have the same influence trend on the flight state, thereby realizing rapid adjustment of the flight state of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Attached Figure 1A schematic diagram of an embodiment of the present invention;

[0021] Attached Figure 2 A schematic diagram of a propeller in an embodiment of the present invention;

[0022] Attached Figure 3 A schematic diagram of the cooperation between the spar and the skin in one embodiment of the present invention;

[0023] Attached Figure 4 A schematic diagram of deformation of a wing spar in one embodiment of the present invention;

[0024] Attached Figure 5 A schematic diagram of a wing spar in one embodiment of the present invention;

[0025] Attached Figure 6 A schematic diagram of a wing spar according to another embodiment of the present invention;

[0026] Attached Figure 7 A schematic diagram of a second connecting member in an embodiment of the present invention;

[0027] Attached Figure 8 A schematic diagram of the change of the propeller pitch over time in an embodiment of the present invention;

[0028] Attached Fig. 9 This is a schematic diagram of the change of tension over time in one embodiment of the present invention;

[0029] Attached Fig.10 The figure is a schematic diagram of the change of the blade rotation speed with time in one embodiment of the present invention.

[0030] Among them, 1. skin; 2. wing beam; 3. blade; 4. upper wing beam; 5. lower wing beam; 6. transmission shaft; 7. hub; 8. first connecting piece; 9. bushing; 10. variable pitch main shaft; 11. toothed protrusion; 12. slot. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0032] The purpose of the present invention is to provide an adaptive variable pitch blade, which enables the pitch to change with the rotation speed through an anisotropic wing beam, thereby improving the response speed of the aircraft when the flight state needs to be changed.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] refer to Figure 1-7 The adaptive variable pitch blade disclosed in the embodiment of the present invention comprises: a skin 1 and a spar 2, the spar 2 is anisotropic, the skin 1 is wrapped around the outside of the spar 2 to form a blade 3, the thickness direction of the spar 2 is arranged in the vertical direction, the width direction of the spar 2 is arranged in the horizontal direction, and at the end close to the root of the blade 3, the thickness of the spar 2 is greater than the width of the spar 2; when the rotation speed of the blade 3 changes, the bending moment force on the spar 2 also changes accordingly, and under the bending-torsion coupling effect, the spar 2 can convert the bending moment force into a torsional force with the geometric centroid of the extension direction of the spar 2 as the torsional center, and the torsional force can drive the skin 1 to produce corresponding deflection, so that the pitch of the blade 3 can be synchronized Specifically, when the rotation speed of blade 3 increases, the pitch of blade 3 increases, and when the rotation speed of blade 3 decreases, the pitch of blade 3 decreases; as the pitch increases, the air inlet angle of blade 3 also increases, which means that the contact between blade 3 and the air is more effective, and more air can be pushed per unit time, thereby generating greater lift, that is, the pitch and rotation speed have the same influence trend on the flight state, and an increase in the rotation speed and an increase in the pitch are both conducive to an increase in the lift provided by blade 3, and a decrease in the rotation speed and a decrease in the pitch are both conducive to a decrease in the lift provided by blade 3, which greatly improves the response speed of an aircraft using blade 3 when the flight state needs to be changed, so that the flight state of the aircraft can be quickly adjusted.

[0035] Those skilled in the art can understand that: under the premise of ensuring that the blade 3 can provide flight force, the shape of the blade 3 in the present application can be any blade shape known in the prior art, and no specific limitation is made here.

[0036] Preferably, the spar is made of composite material.

[0037] Preferably, the spar is made of anisotropic material.

[0038] As a preferred embodiment, based on rotor aerodynamics, the thickness of the spar 2 gradually decreases along the extension direction of the spar 2, that is, the airfoil of the blade tip adopts a thin airfoil, which can avoid airflow separation in the blade tip area as much as possible.

[0039] As a preferred embodiment, it also includes an upper wing beam 4 and a lower wing beam 5, both of which are arranged in an arc shape, the convex side of the upper wing beam 4 is connected to the skin 1, and the concave side of the upper wing beam 4 is connected to one side of the spar 2 in the thickness direction, the convex side of the lower wing beam 5 is connected to the skin 1, and the concave side of the lower wing beam 5 is connected to the other side of the spar 2 in the thickness direction; the arrangement of the upper wing beam 4 and the lower wing beam 5 increases the connection area between the spar 2 and the skin 1, so that the surface of the blade 3 can withstand a larger load. At the same time, the increase in the connection area makes it easier for the skin 1 as a whole to deform following the torsion of the spar 2, thereby amplifying the effect of the torsional deformation of the spar 2.

[0040] Preferably, the geometric centroid of the spar 2 coincides with the quarter chord of the blade 3; based on rotor aerodynamics, the coincidence of the quarter chord with the geometric centroid of the airfoil can ensure that the blade has a higher pitch moment stability during rotation.

[0041] As a preferred embodiment, the wing beam 2 is made of high-strength carbon fiber material; further, the skin 1 is also made of carbon fiber material.

[0042] Preferably, the spar 2 is made of glass fiber material.

[0043] Furthermore, foam material is filled between the skin 1 and the wing spar 2; specifically, the wing spar 2, the upper wing surface beam 4 and the lower wing surface beam 5 are interconnected to form a basic frame of the blade 3, the skin 1 is covered on the outside of the basic frame, and the gap between the skin 1 and the basic frame is filled with foam material; further, a counterweight block is also filled between the skin 1 and the wing spar 2 to meet the requirements of stiffness and strength.

[0044] As a preferred embodiment, the skin 1 is made of three layers of symmetrical carbon fiber plies; preferably, the ply direction is ±45°.

[0045] The present invention also discloses a propeller, which uses the above-mentioned adaptive variable pitch blades. The propeller includes a transmission shaft 6 and a hub 7. The transmission shaft 6 is connected to a power output device. The input end of the hub 7 is connected to the transmission shaft 6, and the output end of the hub 7 is connected to the blade 3. The hub 7 is an adjustable pitch hub. The adjustable pitch hub 7 can pre-adjust the pitch before the propeller rotates to adapt to different flight modes. The power provided by the power output device is transmitted to the blade 3 through the transmission shaft 6 and the hub 7 to drive the entire propeller to rotate.

[0046] Taking the stable flight of the aircraft as the initial state, when the flight altitude of the aircraft needs to be increased, the output speed and output torque of the power output device increase and are transmitted to the hub 7 and the blades 3 through the transmission shaft 6. At this time, due to the increase in the torque value received by the wing beam 2, under the bending-torsion coupling effect, the torsion of the wing beam 2 increases accordingly, thereby causing the pitch of the blades 3 to increase synchronously. Under the joint action of the speed and pitch, the lift provided by the propeller will increase rapidly, so that the flight altitude of the aircraft can be quickly increased; when the flight altitude of the aircraft needs to be reduced, the output speed and output torque of the power output device are reduced. At this time, due to the decrease in the torque value received by the wing beam 2, the torsion of the wing beam 2 decreases accordingly, thereby causing the pitch of the blades 3 to decrease synchronously. Under the joint action of the speed and pitch, the lift provided by the propeller will decrease rapidly, so that the flight altitude of the aircraft can be quickly reduced, thereby achieving a rapid response of the flight state of the aircraft.

[0047] As a preferred embodiment, the propeller also includes a first connecting member 8, one end of the first connecting member 8 is connected to the hub 7, and the other end of the first connecting member 8 is connected to the blade 3. The first connecting member 8 is made of a flexible composite material and can achieve elastic deformation. When the pitch of the blade 3 changes with the twisting of the blade 3, the first connecting member 8 can rotate with the blade 3 so that the blade 3 can produce a larger angle of deflection, thereby widening the range of pitch variation. It can be understood that the first connecting member 8 has a higher strength along the centrifugal direction, which can meet the centrifugal force requirements of the blade 3 under high-speed rotation conditions.

[0048] Furthermore, a smooth transition structure is provided between the first connecting member 8 and the blade 3 and between the first connecting member 8 and the hub 7 to ensure that the propeller has good aerodynamic performance when working.

[0049] Preferably, the first connecting member 8 can be a part of the blade 3. Specifically, the first connecting member 8 is an extension of the root of the blade 3, and the skin 1 at the corresponding position is processed with a smooth transition to form a smooth transition structure, which is filled with a wing beam 2, a counterweight block and foam material.

[0050] As a preferred embodiment, it also includes a second connecting member, which includes a sleeve 9 and a pitch-changing main shaft 10. A toothed protrusion 11 is arranged on the side wall of the pitch-changing main shaft 10, and a groove 12 for accommodating the toothed protrusion 11 is arranged on the inner wall of the sleeve 9. A rotation space is arranged between the toothed protrusion 11 and the groove 12 along the rotation direction of the pitch-changing main shaft 10. The sleeve 9 is connected to the hub 7, and the pitch-changing main shaft 10 is connected to the blade 3. The matching of the sleeve 9 and the pitch-changing main shaft 10 can limit the pitch angle of the blade 3 to avoid the problem of gas-elastic divergence. When the blade rotates, the rotation space allows the pitch-changing main shaft 10 to rotate, and the pitch-changing main shaft 10 drives the wing beam 2 to rotate, and finally transmits the pitch-changing torque to the blade 3, thereby realizing the pitch-changing effect of the blade 3.

[0051] As a preferred implementation, the corresponding relationship between the pitch and the rotation speed is shown in the following table:

[0052]

[0053] Note: The reference operating condition is the rotor speed of 1150rpm rated speed and 8deg rated pitch. Scheme 1 is the case of constant pitch and increased speed. Schemes 2-5 correspond to the rotor aerodynamic response when the pitch degrees are 0.5, 1, 1.5, and 2deg respectively.

[0054] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0055] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

Claims

1. An adaptive variable pitch blade, characterized in that: include: A skin (1) and an anisotropic spar (2), wherein the skin (1) is wrapped around the outside of the spar (2) to form a blade (3), the thickness direction of the spar (2) is arranged in the vertical direction, the width direction of the spar (2) is arranged in the horizontal direction, and the thickness of the spar (2) at one end close to the root of the blade (3) is greater than the width.

2. The adaptive variable pitch blade according to claim 1, characterized in that: Along the extension direction of the wing spar (2), the thickness of the wing spar (2) gradually decreases.

3. The adaptive variable pitch blade according to claim 1, characterized in that: It also includes an upper wing beam (4) and a lower wing beam (5), wherein the upper wing beam (4) and the lower wing beam (5) are both arranged in an arc shape, the convex side of the upper wing beam (4) is connected to the skin (1), and the concave side of the upper wing beam (4) is connected to one side of the wing beam (2) in the thickness direction, the convex side of the lower wing beam (5) is connected to the skin (1), and the concave side of the lower wing beam (5) is connected to the other side of the wing beam (2) in the thickness direction.

4. The adaptive variable pitch blade according to claim 1, characterized in that: The geometric centroid of the wing beam (2) coincides with the quarter chord line of the blade (3).

5. The adaptive variable pitch blade according to claim 1, characterized in that: The wing beam (2) is made of carbon fiber material.

6. The adaptive variable pitch blade according to claim 1, characterized in that: The space between the skin (1) and the wing beam (2) is filled with foam material.

7. The adaptive variable pitch blade according to claim 1, characterized in that: The skin (1) is manufactured by means of three-layer symmetrical carbon fiber plying.

8. A propeller, characterized in that: The adaptive variable pitch blade according to any one of claims 1 to 7 comprises a transmission shaft (6) and a hub (7), wherein the transmission shaft (6) is connected to a power output device, an input end of the hub (7) is connected to the transmission shaft (6), an output end of the hub (7) is connected to the blade (3), and the hub (7) is an adjustable pitch hub (7).

9. The propeller according to claim 8, characterized in that The invention also comprises a first connecting member (8), one end of which is connected to the hub (7), and the other end of which is connected to the blade (3), and the first connecting member (8) is made of a flexible composite material so as to rotate with the blade (3) when the pitch of the blade (3) changes.

10. The propeller according to claim 8, characterized in that The invention also comprises a second connecting member, which comprises a shaft sleeve (9) and a pitch-changing main shaft (10); a tooth-shaped protrusion (11) is arranged on the side wall of the pitch-changing main shaft (10); a groove (12) for accommodating the tooth-shaped protrusion (11) is arranged on the inner wall of the shaft sleeve (9); a rotation space is arranged between the tooth-shaped protrusion (11) and the groove (12) along the rotation direction of the pitch-changing main shaft (10); the shaft sleeve (9) is connected to the propeller hub (7); and the pitch-changing main shaft (10) is connected to the propeller blade (3).

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