Bearing-free paddle connecting structure

Abstract

The invention belongs to the technical field of helicopter rotor structures, and particularly relates to a bearingless paddle connecting structure. Comprising a flexible beam, two supporting bearings, a supporting bearing support, a support fixing bolt, a cover plate, a cover plate connecting bolt, a wear-resisting plate, a tail shaft, blades and a tail rotor flange, the two ends of the flexible beam are each provided with one blade, the flexible beam and the blades are integrally formed, and the roots of the blades are connected with the tail rotor flange through bolts. The supporting bearing support is fixed to the flexible beam through support fixing bolts and used for supporting the two supporting bearings on the upper side and the lower side of the flexible beam. One end of the support bearing is connected with the tail rotor flange, and the other end is connected with the support bearing bracket; the flexible beam is clamped between the cover plate and the tail shaft, and a wear-resisting plate is arranged on the clamping interface of the cover plate and the flexible beam and is fixed through a cover plate connecting bolt.

Description

Technical Field

[0001] The invention belongs to the technical field of helicopter rotor structures, and in particular relates to a bearingless blade connection structure. Background Art

[0002] The bearingless tail rotor is an advanced tail rotor configuration that has been applied to multiple helicopter models at home and abroad. Its tail rotor blade assembly is mainly composed of three parts: a flexible beam, a sleeve and a tail rotor blade airfoil section. Since the flexible beam and the sleeve do not move synchronously, a dual-path force transmission structure is designed; the sleeve is bonded to the flexible beam near the tip and connected at the root through a support bearing, where the support bearing is a pair of elastic bearings with three translational stiffnesses and three rotational stiffnesses; the flexible beam is the core component of the bearingless tail rotor, replacing the horizontal hinge, vertical hinge and axial hinge of the traditional articulated tail rotor, and realizing the flapping, swinging and pitch-changing movement of the blades through elastic deformation.

[0003] The most difficult part of the bearingless tail rotor design is the long life design of the central connection area and the flapping deformation area. During the use and testing of the tail rotor flexible beam, a series of problems such as high scrap rate caused by insufficient life margin, premature damage during use leading to scrapping, and fracture of the flexible beam under high load conditions were exposed. Summary of the invention

[0004] Purpose of the invention: To provide a bearingless blade connection structure to reduce the strain in the flexible beam connection area and increase the service life of the flexible beam.

[0005] Technical solution:

[0006] A bearingless blade connection structure includes: a flexible beam 1, two support bearings 2, a support bearing bracket 3, a bracket fixing bolt 4, a cover plate 6, a cover plate connecting bolt 7, a wear-resistant plate 8, a tail shaft 9, a blade 10, and a tail rotor flange 11, wherein:

[0007] A blade 10 is provided at each end of a flexible beam 1, and the flexible beam 1 and the blade 10 are integrally formed. The root of the blade 10 is connected to the tail rotor flange 11 by bolts, and the support bearing bracket 3 is fixed to the flexible beam 1 by the bracket fixing bolts 4 to support two support bearings 2 on the upper and lower sides of the flexible beam 1; one end of the support bearing 2 is connected to the tail rotor flange 11, and the other end of the support bearing 2 is connected to the support bearing bracket 3; the flexible beam 1 is clamped between the cover plate 6 and the tail shaft 9, and a wear-resistant plate 8 is provided on the clamping interface between the cover plate 6 and the flexible beam 1, and is fixed with the cover plate connecting bolts 7.

[0008] Furthermore, the thickness of the central region of the flexible beam 1 is greater than that of other regions, thereby increasing its rigidity to reduce strain, so that the deformation region of the flexible beam 1 moves outward.

[0009] Furthermore, protruding ears are added on both sides of the flexible beam 1, and upper flanges are provided on both sides of the tail shaft 9. The flange positions and the protruding ears added on both sides of the flexible beam 1 are conformal and are used to mechanically limit the flexible beam 1 to prevent the flexible beam from slightly rotating along the central tail shaft and causing wear.

[0010] Furthermore, the flexible beam 1 and the cover plate 6 are fixed by four cover plate connecting bolts 7 .

[0011] Furthermore, it also includes: a bracket middle bolt 5, which connects the support bearing bracket 3 with the deformation area of ​​the flexible beam 1.

[0012] Furthermore, the wear-resistant plate 8 is thin in the middle and thick at both sides, and the interface with the flexible beam 1 is designed to be an arc surface, which fits tightly with the flexible beam 1, thereby reducing the clamping force between the flexible beam 1 and the edge of the wear-resistant plate 8 during deformation and reducing local stress concentration.

[0013] Furthermore, the connection hole area in the length direction of the flexible beam 1 is disconnected from the deformation area of ​​the flexible beam 1 by the crescent groove, so as to avoid the flexible beam 1 being squeezed with the edge of the cover plate 6 when deforming, thereby preventing stress concentration.

[0014] Furthermore, the central area of ​​the flexible beam 1 is thickened by adding layers or beam belts.

[0015] Beneficial effects:

[0016] The present invention proposes a structure for the flexible beam connection area of ​​a bearingless tail rotor. Experimental tests have shown that the structure effectively reduces the strain in the flexible beam connection area and significantly improves the service life of the flexible beam. This invention can be extended to all bearingless rotors / tail rotors. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a bearingless tail rotor, showing the connection relationship between the flexible beam 1, the support bearing 2, and the blade 10;

[0018] Figure 2 It is a schematic diagram of the central connection area, showing the connection relationship between the central section flexible beam 1, the cover plate 6 and the tail shaft 9;

[0019] Figure 3 It is a schematic diagram of the shape of the wear-resistant plate;

[0020] Figure 4 It is a schematic diagram of the middle section of the flexible beam;

[0021] Figure 5 The schematic diagram of the principle analysis of the influence of the shape of the wear-resistant plate on the strain of the middle connection area of ​​the flexible beam;

[0022] Among them, there are flexible beam 1, support bearing 2, support bearing bracket 3, bracket fixing bolt 4, bracket middle bolt 5, cover plate 6, cover plate connecting bolt 7, wear-resistant plate 8, tail shaft 9, blade 10, and tail rotor flange 11. DETAILED DESCRIPTION

[0023] The bearingless blade connection structure of the present invention reduces the load of the flexible beam in the connection area and increases the service life of the flexible beam.

[0024] The following is an explanation using the tail rotor as an example with reference to the accompanying drawings.

[0025] like Figure 1-4 A bearingless blade connection structure includes: a flexible beam 1, a support bearing 2, a support bearing bracket 3, a bracket fixing bolt 4, a bracket middle bolt 5, a cover plate 6, a cover plate connecting bolt 7, a wear-resistant plate 8, a tail shaft 9, a blade 10, and a tail rotor flange 11. A flexible beam 1 is connected to a blade 10 at each end, wherein the blade 10 is connected to the tail rotor flange 11 by bolts, and the flexible beam 1 is fixed in the inner cavity at the root of the blade 10. The flexible beam 1 is connected to the root section of the blade 10 through two support bearings 2, the support bearing 2 is fixed to the support bearing bracket 3 by bolt connection, the support bearing bracket 3 is fixed to the flexible beam 1 by the bracket fixing bolt 4, and a bracket middle bolt 5 is added in the middle; the flexible beam 1 is clamped between the cover plate 6 and the tail shaft 9, a wear-resistant plate 8 is added to the clamping interface between the cover plate 6 and the flexible beam 1, and fixed with the cover plate connecting bolt 7.

[0026] The central area of ​​the flexible beam 1 is thickened by adding plies or beam strips to increase its rigidity to reduce strain, so that the deformation area of ​​the flexible beam 1 moves outward;

[0027] The flexible beam 1 is provided with protruding ears on both sides, which cooperate with the end faces on both sides of the tail shaft 9 to increase mechanical limit and prevent the flexible beam from slightly rotating along the central tail shaft and causing wear;

[0028] The flexible beam 1 and the cover plate 6 are fixed by four cover plate connecting bolts 7; the connecting hole area in the length direction is disconnected from the deformation area of ​​the flexible beam 1 by a crescent groove, so as to avoid the flexible beam 1 being squeezed with the edge of the cover plate 6 when deforming, resulting in stress concentration;

[0029] The support bearing 2 is fixed on the support bearing bracket 3, and the load is transferred to the flexible beam 1 through the support bearing bracket 3. Compared with the original solution in which the support bearing is directly bonded to the flexible beam 1, the connection reliability between the support bearing and the flexible beam can be further improved.

[0030] A connecting bolt bracket middle bolt 5 is added in the middle of the support bearing bracket 3, which can move the deformation area of ​​the flexible beam 1 to the outside, reduce the strain level of the flexible beam 1, and thus greatly improve the service life of the flexible beam 1. Figure 5 .

[0031] The wear-resistant plate 8 is designed to be thin in the middle and thick on both sides, wherein the butt joint surface with the flexible beam 1 is designed to be an arc surface, which fits tightly with the flexible beam 1, thereby reducing the clamping force between the flexible beam 1 and the edge of the wear-resistant plate 8 during deformation and reducing local stress concentration.

[0032] The flexible beam 1 is mechanically fixed by the cover plate 6 and the support bearing 2, which more effectively prevents the flexible beam from shaking slightly during the rotation process, reduces the wear on the surface of the flexible beam, and increases the service life of the flexible beam.

Claims

1. A bearingless blade connection structure, characterized in that: include: A flexible beam (1), two supporting bearings (2), a supporting bearing bracket (3), bracket fixing bolts (4), a cover plate (6), a cover plate connecting bolts (7), a wear plate (8), a tail shaft (9), a blade (10), and a tail rotor flange (11), wherein: A blade (10) is provided at each end of a flexible beam (1), the flexible beam (1) and the blade (10) are integrally formed, the root of the blade (10) is connected to a tail rotor flange (11) by bolts, a support bearing bracket (3) is fixed to the flexible beam (1) by bracket fixing bolts (4) to support two support bearings (2) on the upper and lower sides of the flexible beam (1); one end of the support bearing (2) is connected to the tail rotor flange (11), and the other end of the support bearing (2) is connected to the support bearing bracket (3); the flexible beam (1) is clamped between a cover plate (6) and a tail shaft (9), a wear-resistant plate (8) is provided on the clamping interface between the cover plate (6) and the flexible beam (1), and is fixed by a cover plate connecting bolt (7).

2. The bearingless blade connection structure according to claim 1, characterized in that: The thickness of the central region of the flexible beam (1) is greater than that of other regions, thereby increasing its rigidity to reduce strain, so that the deformation region of the flexible beam (1) moves outward.

3. The bearingless blade connection structure according to claim 1, characterized in that: Protruding ears are added on both sides of the flexible beam (1), and upper flanges are provided on both sides of the tail shaft (9). The flange positions and the protruding ears added on both sides of the flexible beam (1) are conformal and are used to mechanically limit the flexible beam (1) to prevent the flexible beam from slightly rotating along the central tail shaft and causing wear.

4. The bearingless blade connection structure according to claim 1, characterized in that: The flexible beam (1) and the cover plate (6) are fixed via four cover plate connecting bolts (7).

5. The bearingless blade connection structure according to claim 1, characterized in that: Also includes: The middle bolt (5) of the bracket connects the supporting bearing bracket (3) with the deformation area of ​​the flexible beam (1).

6. The bearingless blade connection structure according to claim 1, characterized in that: The wear-resistant plate (8) is thin in the middle and thick at both sides, and the interface with the flexible beam (1) is designed to be an arc surface, which fits tightly with the flexible beam (1), thereby reducing the pressing force between the flexible beam (1) and the edge of the wear-resistant plate (8) during deformation, thereby reducing local stress concentration.

7. The bearingless blade connection structure according to claim 1, characterized in that: The connection hole area in the length direction of the flexible beam (1) is disconnected from the deformation area of ​​the flexible beam (1) by the crescent groove, thereby preventing the flexible beam (1) from being squeezed with the edge of the cover plate (6) when deforming, thereby preventing stress concentration.

8. The bearingless blade connection structure according to claim 1, characterized in that: The central area of ​​the flexible beam (1) is thickened by adding plies or beam strips.

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