Bearing-free tail rotor structure

Abstract

The invention belongs to the technical field of helicopter rotor structures, and particularly relates to a bearingless tail rotor structure. Comprising M pull rod assemblies, a fork-shaped piece, a tail shaft, a clamping plate, M bolts, M nuts and M paddle assemblies, each paddle assembly comprises a flexible beam, a paddle, two supporting bearings, a crankshaft and a spherical hinge, and the two ends of each pull rod assembly are connected with the corresponding paddle and the fork-shaped piece respectively; one end of the flexible beam and the paddle are solidified into a whole through mould pressing, the other end of the flexible beam is forked into fork lugs, the left fork lug is connected with the tail shaft and the clamping plate through a left side bolt and a left side nut, and the right fork lug is connected with the tail shaft and the clamping plate through a right side bolt and a right side nut; a spherical hinge is clamped between adjacent flexible beam fork lugs, an upper supporting bearing and a lower supporting bearing which are the same are fixed to the end face of each paddle, the supporting bearings are connected through a crankshaft, and the spherical hinges penetrate through the middles of the crankshafts and are connected with middle bolts in a sleeved mode through single lug rings on the spherical hinges.

Description

Technical Field

[0001] The present invention belongs to the technical field of helicopter rotor configurations, and particularly relates to a bearingless tail rotor structure. Background Art

[0002] During operation, the tail rotor rotates at a very high speed, and each blade generates a huge centrifugal force. In order to reduce the load on the hub of traditional bearingless tail rotors, a shoulder-type symmetric structure is usually adopted, that is, a pair of blades are connected by a flexible beam, so that the centrifugal forces act on the same flexible beam along a straight line and cancel each other out. Although this symmetrically distributed blade effectively reduces the load on the hub center, there are also obvious defects. One is that the number of tail rotor blades can only be an even number, such as 2, 4, 6, etc., resulting in relatively weak designability of the tail rotor and difficulty in significantly reducing the weight. The second is that when one of the blades is defective, a pair of blades and the flexible beam need to be returned to the factory for repair or scrapped simultaneously, resulting in high usage costs. The third is that traditional tail rotors prevent crosstalk by pressing the flexible beam with upper and lower pressure plates, and there is fretting wear after long-term use, leading to premature damage of the flexible beam. There are also helicopters with main rotors adopting bearingless configurations. In order to connect the blades, various hub structures will be designed. Due to the large number of hub parts and high material density, the weight of the final rotor structure is relatively heavy. Summary of the Invention

[0003] Object of the Invention: To provide a bearingless tail rotor structure that realizes the functions of the tail rotor while simplifying the tail rotor structure, reducing the weight of the tail rotor, and having the function of replaceable single blades.

[0004] Technical Solution:

[0005] A bearingless tail rotor structure includes: M tie rod assemblies 3, a fork-shaped part 4, a tail shaft 5, a clamping plate 6, M bolts 7, M nuts 8, and M blade assemblies. Each blade assembly includes: a flexible beam 1, a blade 2, two support bearings 9, a crankshaft 10, and a ball joint 11.

[0006] Wherein, each blade assembly corresponds to three adjacent bolts 7 and three nuts 8. The left blade assembly and the adjacent right blade on one side are arranged with a dislocation of one bolt 7 and one nut 8 respectively. Both ends of the tie rod assembly 3 are respectively connected to the blade 2 and the fork-shaped part 4. One end of the flexible beam 1 is integrally formed with the blade 2 by molding. The other end of the flexible beam 1 branches into fork ears. The left fork ear is respectively connected to the tail shaft 5 and the clamping plate 6 through a left bolt 7 and a left nut 8. The right fork ear is respectively connected to the tail shaft 5 and the clamping plate 6 through a right bolt 7 and a right nut 8. A ball joint 11 is sandwiched between adjacent flexible beam fork ears. Two identical support bearings 9 are fixed on the blade end face, and the support bearings are connected by a crankshaft 10. Among them, the ball joint 11 passes through the middle of the crankshaft and is sleeved with the middle bolt 7 through a single earring on the ball joint 11.

[0007] Further, the forked member 4 passes through the tail shaft 5 in the middle, and the pitch change movement of the blade 2 is realized by the up and down sliding of the forked member 4 along the tail shaft 5.

[0008] Further, the flexible beam 1 is formed by winding glass tapes or laying composite materials, with one end designed in a rectangular cross-section shape and inserted into the blade, and the other end designed in a fork-ear shape and connected to the bolt 7.

[0009] Further, the fork ear of the flexible beam 1 is close to the rotation center of the tail rotor, which is beneficial to moving the equivalent flapping hinge of the flexible beam 1 towards the center, thereby reducing the loads finally transmitted to the central structural members such as the splint 6 and the tail shaft 5.

[0010] Further, the fork ears of the flexible beam 1 are distributed left and right and up and down. The purpose is to increase the anti-deformation ability in the flapping direction through the left and right forked arrangement, and to improve the anti-deformation ability in the pitch direction through the up and down arrangement.

[0011] Further, gaskets are added to the connection surface between the splint 6 and the bolt 7 to prevent the bolt from loosening.

[0012] Further, gaskets are added between the splint 6 and the flexible beam 1, and an anti-corrosion primer is applied to the bonding interface between the gasket and the flexible beam 1.

[0013] Further, gaskets are added between the flexible beam 1, the tail shaft 5 and the ball joint 11, and an anti-corrosion primer is applied to the bonding interface between the gasket and the flexible beam 1.

[0014] Further, before the start of the forked area of the flexible beam 1, the large beam winding scheme can be used for partial cross-laying, and some large beam tapes can be pasted at the forked opening for curing to prevent the forked opening from cracking.

[0015] Beneficial effects:

[0016] The bearingless tail rotor of the present invention is a type of helicopter tail rotor configuration. Compared with the traditional tail rotor configuration, the bearingless tail rotor has a simpler structure, fewer parts, a higher degree of integration, and a lighter structural weight. Description of the drawings

[0017] Figure 1 Schematic diagram of the bearingless tail rotor;

[0018] Figure 2 Schematic diagram of the connection between the blade and the tail shaft;

[0019] Figure 3 Schematic diagram of the root structure of the blade assembly;

[0020] Figure 4 Schematic diagram of the installation of the root of the flexible beam;

[0021] Among them, there are a flexible beam 1, a blade 2, a tie rod assembly 3, a forked part 4, a tail shaft 5, a clamping plate 6, a bolt 7, a nut 8, a support bearing 9, a crankshaft 10, and a spherical hinge 11. Detailed implementation mode

[0022] To make the purpose, technical solutions, and advantages of the implementation of this application clearer, the technical solutions in the implementation modes of this application will be described in more detail below with reference to the accompanying drawings in the implementation modes of this application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The described implementation modes are part of the implementation modes of this application, rather than all of the implementation modes. The implementation modes described below with reference to the accompanying drawings are exemplary and are intended to explain this application and should not be construed as limiting this application. Based on the implementation modes in this application, all other implementation modes obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application. The implementation modes of this application will be described in detail below with reference to the accompanying drawings.

[0023] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "axial direction", "vertical", "upper", "lower", "upper end", "bottom end", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention.

[0024] Such as Figures 1-4 , a bearingless tail rotor structure, the main structural components include: a flexible beam 1, a blade 2, a tie rod assembly 3, a forked part 4, a tail shaft 5, a clamping plate 6, a bolt 7, a nut 8, a support bearing 9, a crankshaft 10, and a spherical hinge 11. One end of the flexible beam 1 is integrally formed with the blade 2 by molding, and the other end of the flexible beam 2 bifurcates into a fork ear structure. The fork ears are connected to the tail shaft 5 and the clamping plate 6 through the bolt 7 and the nut 8. A spherical hinge 11 is sandwiched between adjacent flexible beam fork ears. Two identical support bearings 9 are fixed on the end face of the blade, and the support bearings are connected by a crankshaft 10, and the spherical hinge 11 passes through the crankshaft.

[0025] The flexible beam 1 and the blade 2 of the bearingless tail rotor are fixed together. The forked part 4 passes through the tail shaft 5 in the middle and can slide up and down. The tie rod assembly 3 connects the blade 2 and the forked part 4, and the pitch change movement of the blade 2 is realized by the forked part 4 sliding up and down along the tail shaft 5.

[0026] During the movement, the movements of the flexible beam 1 and the blade 2 in the root section are not synchronous. Therefore, a spherical hinge 11 is required to connect the blade 2 and the flexible beam 1.

[0027] The flexible beam 1 can be formed by winding a glass tape or layering composite materials. One end is designed to have a rectangular cross-section and is inserted into the blade, while the other end is designed as a fork ear shape and is connected to the bolt 7.

[0028] The fork ear section of the flexible beam 1 is achieved through bifurcation. The bifurcation section is designed to be as close as possible to the rotation center of the tail rotor, which is beneficial to moving the equivalent flapping hinge of the flexible beam 1 towards the center, thereby reducing the load finally transmitted to the central structural components such as the splint 6 and the tail shaft 5.

[0029] The fork ears of the flexible beam 1 are distributed horizontally and vertically. The purpose is to increase the anti-deformation ability in the drag direction through the horizontal bifurcation arrangement, improve the anti-deformation ability in the flapping direction through the vertical arrangement, and at the same time enable the arrangement of 5 or more flexible beams 1 in a very small space, making the design structure more compact and reducing the number of other connecting parts, thereby reducing the overall structural weight.

[0030] The thickness and width of the clamping area at the root of the flexible beam 1 are larger, while the thickness and width of the starting section of the bifurcation are thinner and narrower. The purpose is to concentrate the deformation area of the flexible beam outside the clamping area and prevent collision with the tail shaft 5 or the upper splint 6 during the deformation process.

[0031] The upper splint 6 is a wear-resistant structural component and is connected to the flexible beam 1 and the tail shaft 5 through bolts 7 and nuts 8. The force transmission effect of using bolt connection is more reliable and is not prone to failure.

[0032] The support bearing 9 is designed to have a very large stiffness and small deformation in the flapping and torsion directions, and a small stiffness and easy deformation in the drag direction. The drag movement deformation of the rigid blade 2 is small, and the transmitted drag movement can be offset by the deformation of the support bearing 9.

[0033] The movement generated by the pitch change of the blade 2 and the movement deformation of the flapping are relatively large, and a ball joint 11 is required to eliminate the movement deformation and prevent the movement deformation on the blade from being transmitted to the flexible beam 1.

[0034] A gasket is added to the connection surface between the upper splint 6 and the bolt 7 to prevent the bolt from loosening.

[0035] A gasket is added between the upper splint 6 and the flexible beam 1, and an anti-corrosion primer is applied to the bonding interface between the gasket and the flexible beam 1.

[0036] A gasket is added between the flexible beam 1 and the tail shaft 5 and the ball joint 11, and an anti-corrosion primer is applied to the bonding interface between the gasket and the flexible beam 1.

[0037] Before the start of the bifurcation area of the flexible beam 1, the large beam winding scheme can be used for local cross-laying, and some large beam tapes can be pasted at the bifurcation opening for curing to prevent the bifurcation opening from cracking.

[0038] A layer of fiberglass cloth can be wrapped on the surface of the flexible beam 1 to prevent foreign objects from scratching the flexible beam body.

[0039] See Figures 1 to 2 , the present invention can implement a bearingless tail rotor structure scheme. The outer section of the blade 2 is cured integrally with the flexible beam 1, and the inner section is connected to the flexible beam through a ball joint 11, etc.; the flexible beam 1 is connected to the upper clamping plate 7 and the tail shaft 5 through bolts 7 and nuts 8; the pitch change movement is transmitted to the blade 2 through a fork-shaped member 4 and a pull rod 3 to achieve the collective pitch control of the tail rotor.

[0040] See Figure 3 , the flexible beam 1 of the present invention is designed with a fork at the root end, and the lengths of the forks are inconsistent and not in the same plane. There are two bolt connection holes on the fork ear for connection with the bolt 7.

[0041] See Figure 4 , through the fork design at the root of the flexible beam 1 of the present invention, 5 flexible beams 1 are arranged in a smaller space, and the fork ears of adjacent flexible beams 1 are pressed against each other up and down, reducing unnecessary connecting parts and reducing the weight of the final tail rotor.

[0042] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claimed rights.

Claims

1. A bearingless tail rotor structure, characterized in that, Including: M tie rod assemblies, a forked part, a tail shaft, clamping plates, M bolts, M nuts, and M blade assemblies. Each blade assembly includes: a flexible beam, a blade, two support bearings, a crankshaft, and a ball joint. Wherein, each blade assembly corresponds to three adjacent bolts and three nuts. The left blade assembly and the adjacent right blade on one side are arranged with a dislocation of one bolt and one nut respectively. The two ends of the tie rod assembly are respectively connected to the blade and the forked part. One end of the flexible beam is integrally formed with the blade by molding. The other end of the flexible beam branches into fork ears. The left fork ear is respectively connected to the tail shaft and the clamping plate through a left bolt and a left nut. The right fork ear is respectively connected to the tail shaft and the clamping plate through a right bolt and a right nut. A ball joint is sandwiched between the adjacent flexible beam fork ears. Two identical support bearings are fixed on the end face of the blade. The support bearings are connected by a crankshaft. The ball joint passes through the middle of the crankshaft and is sleeved with the middle bolt through a single earring on the ball joint.

2. The bearingless tail rotor structure according to claim 1, characterized in that, The forked part passes through the middle of the tail shaft, and the blade pitch change movement is realized by the up-and-down sliding of the forked part along the tail shaft.

3. The bearingless tail rotor structure according to claim 1, characterized in that, The flexible beam is formed by winding glass tapes or laying composite materials. One end is designed in a rectangular cross-section shape and inserted into the blade. The other end is designed in a fork ear shape and connected to the bolt.

4. The bearingless tail rotor structure according to claim 1, wherein The flexible beam fork ear is close to the rotation center of the tail rotor, which is beneficial to move the equivalent flapping hinge of the flexible beam towards the center, thereby reducing the load finally transmitted to the central structural parts such as the clamping plate and the tail shaft.

5. The bearingless tail rotor structure according to claim 1, characterized in that The flexible beam fork ears are distributed left and right and up and down. The purpose is to increase the anti-deformation ability in the flapping direction by arranging the left and right bifurcations, and to improve the anti-deformation ability in the pitch direction by arranging up and down.

6. The bearingless tail rotor structure according to claim 1, characterized in that, Gaskets are added to the connection surface between the clamping plate and the bolt to prevent the bolt from loosening.

7. The bearingless tail rotor structure according to claim 1, wherein, Gaskets are added between the clamping plate and the flexible beam, and an anti-corrosion primer is applied to the bonding interface between the gasket and the flexible beam.

8. The bearingless tail rotor structure according to claim 1, wherein, Gaskets are added between the flexible beam and the tail shaft and the ball joint, and an anti-corrosion primer is applied to the bonding interface between the gasket and the flexible beam.

9. The bearingless tail rotor structure according to claim 1, characterized in that, Before the start of the forked area of the flexible beam, a large beam winding scheme can be adopted for local cross-laying, and part of the large beam tape can be pasted at the forked opening for curing to prevent the forked opening from cracking.

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