A twist strip type helicopter tail rotor hub

Abstract

The present invention belongs to the technical field of helicopter rotor hubs, and provides a twist bar type helicopter tail rotor hub, which aims to solve the problems in the prior art that the hub is heavy, has a relatively short life, is difficult to maintain, and has a high manufacturing and use cost. A twist bar type helicopter tail rotor hub, comprising a center cross fork assembly mounted on a hub fork assembly, on which a blade arm assembly is mounted; the blade arm assembly is fixed to the center cross fork assembly through a twist bar assembly; the hub fork assembly is mounted on an output shaft, and the center cross fork assembly is rotatably connected to the hub fork assembly around a rotation axis perpendicular to the axis of the output shaft. By using a twist bar assembly instead of a bearing, the hub has a lighter overall mass, a relatively longer life, is easy to maintain, and has a low manufacturing and use cost.

Description

Technical Field

[0001] The invention belongs to the technical field of helicopter rotor hubs, and in particular relates to a twist-strip type helicopter tail rotor hub. Background Art

[0002] The most commonly used structure of the tail rotor hub of existing light helicopters is bearing-based, which mainly uses rolling bearings to achieve the pitch change of the rotor blades, and uses angular contact bearings or thrust ball bearings to bear the centrifugal force when the blades rotate. Due to the large number of bearings, this structure is generally larger in overall size, heavier in weight, and has a relatively short lifespan and is difficult to maintain. Summary of the invention

[0003] The invention provides a twist strip type helicopter tail rotor hub, aiming to solve the problems in the prior art that the hub is heavy, has a relatively short life, is difficult to maintain, and has a high manufacturing and use cost.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A twist-strip type helicopter tail rotor hub comprises a central cross fork assembly mounted on a hub fork assembly, wherein a blade arm assembly is mounted on the central cross fork assembly;

[0006] The blade support arm assembly is fixed to the central cross fork assembly through a torsion bar assembly;

[0007] The hub fork assembly is mounted on the output shaft, and the center cross fork assembly is rotatably connected to the hub fork assembly around a rotation axis perpendicular to the axis of the output shaft.

[0008] A further improved solution: there are two blade arm assemblies, and the two blade arm assemblies are symmetrically arranged about the central cross fork assembly. One end of the torsion bar assembly is connected to one of the blade arm assemblies, and the other end of the torsion bar assembly is connected to the other blade arm assembly.

[0009] Based on the above technical solution: the pull-twist strip assembly is set to be integrated, which has a simple structure compared to the split distribution method, can improve the reliability of the product, and at the same time reduce the product weight and production costs.

[0010] A further improved solution: a central pressing block for fixing the twist bar assembly is arranged inside the central cross fork assembly, and the distances from both ends of the twist bar assembly to the central pressing block are equal.

[0011] Based on the above technical solution: by setting a central pressure block, the central pressure block is used to fix the center position of the torsion bar assembly to prevent the torsion force on the torsion bar assembly from being unevenly distributed and the torsion position from being offset when the blade changes pitch.

[0012] A further improved solution: the torsion strip assembly comprises at least two metal strips stacked together.

[0013] Based on the above technical solution: the tension-torsion bar assembly is composed of multiple layers of metal bars stacked together, which can well withstand the torsional force when the blades change pitch and the centrifugal force generated when rotating at high speed.

[0014] A further improved solution: the torsion bar assembly is fixed to the blade arm assembly by a first locking bolt, an inner fixing bushing for fixing the torsion bar assembly is provided on the side of the first locking bolt close to the center cross fork assembly, and an outer fixing bushing for fixing the torsion bar assembly is provided on the side of the locking bolt away from the inner fixing bushing.

[0015] Based on this technical solution: it is used to lock the two sides of the pull-twist strip assembly to prevent the pull-twist strip assembly from delamination.

[0016] A further improved solution: the inner fixing bushing and the outer fixing bushing are both fixed by the first locking bolt.

[0017] Based on this technical solution: the fixing structure of the inner fixed bushing and the outer fixed bushing is simplified, so that the first locking bolt can lock the torsion strip assembly while locking the inner fixed bushing and the outer fixed bushing, thereby simplifying the structure of the rotor hub.

[0018] A further improved solution: a vibration-damping rubber pad is provided between the propeller hub fork assembly and the output shaft.

[0019] Based on the above technical solution: it is used to play a buffering role when the blades perform pitch change movement to prevent the hub fork assembly from interfering with the output shaft.

[0020] A further improved solution: the hub fork assembly includes a hub fork arranged on the output shaft, the hub fork is provided with two fork pieces for fixing the center cross fork assembly, the center cross fork assembly is fixed to the fork piece by a second locking bolt, and a bearing is provided between the second locking bolt and the fork piece.

[0021] Based on the above technical solution: the propeller hub fork assembly and the center cross fork assembly are easy to assemble, and the center cross fork assembly is flexible in movement by providing fork sheets and bearings.

[0022] A further improved solution: the bearing is a deep groove ball bearing.

[0023] Based on the above technical solution: the deep groove ball bearing has better performance, can withstand axial and radial forces, and prolongs the service life of the bearing.

[0024] A further improved solution: an adjustment pad is provided between the central cross fork assembly and the fork piece, one side of the adjustment pad is in contact with the central cross fork assembly, and the other end of the adjustment pad is in contact with the fork piece.

[0025] Based on the above technical solution: an adjustment pad is provided at the connection between the center cross fork assembly and the hub fork assembly, which can conveniently adjust the distance between the two to prevent interference when the distance is too small or the problem of excessive distance.

[0026] A further improved solution: the blade arm assembly is sleeved on the center cross fork assembly, and a self-lubricating bushing is provided between the blade arm assembly and the center cross fork assembly.

[0027] Based on the above technical solution: the pitch can be changed more smoothly and the maintenance cost can be saved.

[0028] A further improved solution: a retaining ring is provided between one end of the self-lubricating bushing close to the hub fork assembly and the center cross fork assembly.

[0029] Based on the above technical solution: the retaining ring is used to increase the axial force-bearing area of ​​the self-lubricating bushing and reduce its deformation.

[0030] The beneficial effects of the present invention are:

[0031] The tail rotor of a helicopter undergoes the following movements during normal operation. Assuming that the plane perpendicular to the axis of the output shaft is taken as the reference plane, the tail rotor blade arm assembly and the cross fork assembly as a whole rotate around the axis of the output shaft within the reference plane, the cross fork assembly at the center of the tail rotor as a whole swings up and down relative to the reference plane, and the tail rotor arm assembly performs blade pitch change movement around their respective pitch change axes. The above three movements are the follow-up movements of the tail rotor hub after releasing the degrees of freedom in various directions.

[0032] Therefore, the tail rotor hub of the helicopter should meet the requirements of the above-mentioned rotation, flapping and pitch change movements of the blades. It adopts a torsion bar assembly design to withstand the centrifugal force of the tail rotor blades when they rotate, while releasing the degrees of freedom of the tail rotor blades in the pitch change direction. The bearingless design reduces the overall size and mass of the hub structure.

[0033] The use of a torsion strip assembly instead of the bearing design eliminates the lubrication system design of the internal bearing, reducing the risk of lubricating oil leaking and contaminating the tail rotor blades under the action of centrifugal force, keeping the tail rotor hub and blade surface clean, and reducing maintenance costs.

[0034] By using torsion bar assemblies instead of bearings, the hub has a lighter overall mass, a relatively longer service life, easier maintenance, and lower manufacturing and use costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For users of ordinary technology in the field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a schematic diagram of a twist strip type helicopter tail rotor hub of the present invention.

[0037] Figure 2 The present invention is a schematic diagram of the internal structure of a central cross fork assembly of a twist strip type helicopter tail rotor hub.

[0038] Figure 3 The present invention is a schematic diagram of the internal structure of the connection between the hub fork assembly and the center cross fork assembly in a pull-twist strip type helicopter tail rotor hub.

[0039] Description of the numbers in the figure:

[0040] 1-blade arm assembly; 2-center cross fork assembly; 3-hub fork assembly; 11-blade arm; 12-inner fixed bushing; 13-outer fixed bushing; 14-first locking bolt; 21-center cross fork; 22-twist bar assembly; 23-center pressure block; 24-adjustment pad; 25-retaining ring; 26-self-lubricating bushing; 31-hub fork; 32-vibration damping rubber pad; 33-bearing; 34-second locking bolt. DETAILED DESCRIPTION

[0041] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by users of the present invention without creative work belong to the protection scope of the present invention.

[0042] Embodiment 1:

[0043] See also Figures 1 to 3 A twist-strip type helicopter tail rotor hub comprises a center cross fork assembly 2 mounted on a hub fork assembly 3, wherein a blade arm assembly 1 is mounted on the center cross fork assembly 2;

[0044] The blade support arm assembly 1 is fixed to the central cross fork assembly 2 through a torsion bar assembly 22;

[0045] The hub fork assembly 3 is mounted on the output shaft, and the center cross fork assembly 2 is rotatably connected to the hub fork assembly 3 around a rotation axis perpendicular to the axis of the output shaft.

[0046] The blade support arm assembly 1 includes a blade support arm 11 for mounting a blade. The center cross fork assembly 2 includes a center cross for connecting the blade support arm 11 with an output shaft.

[0047] Embodiment 2:

[0048] See also Figures 2 to 3 In order to optimize the performance of the twist bar assembly and make the twist bar assembly simple in structure and good in stability, on the basis of the above embodiment: there are two blade arm assemblies 1, and the two blade arm assemblies 1 are symmetrically arranged about the center cross fork assembly 2, one end of the twist bar assembly 22 is connected to one of the blade arm assemblies 1, and the other end of the twist bar assembly 22 is connected to the other blade arm assembly 1.

[0049] A central pressing block 23 for fixing the torsion bar assembly 22 is disposed inside the central cross assembly 2 , and the distances from both ends of the torsion bar assembly 22 to the central pressing block 23 are equal.

[0050] The central pressing block 23 can be fixed between the central cross fork assembly 2 and the tension and twist bar assembly 22 in any manner.

[0051] The twist bar assembly 22 includes at least two metal bars stacked together.

[0052] The torsion bar assembly 22 is fixed to the blade arm assembly 1 by a first locking bolt 14, and an inner fixing bushing 12 for fixing the torsion bar assembly 22 is provided on the side of the first locking bolt close to the center cross fork assembly 2, and an outer fixing bushing 13 for fixing the torsion bar assembly 22 is provided on the side of the locking bolt away from the inner fixing bushing 12.

[0053] The inner fixing bushing 12 and the outer fixing bushing 13 are both fixed by the first locking bolt 14 .

[0054] Embodiment three:

[0055] See also Figures 2 to 3 In order to optimize the connection structure between the propeller housing fork assembly and the output shaft, based on the above embodiment: a vibration-damping rubber pad 32 is provided between the propeller hub fork assembly 3 and the output shaft.

[0056] The hub fork assembly 3 includes a hub fork 31 arranged on the output shaft, and the hub fork 31 is provided with two fork plates for fixing the center cross fork assembly 2. The center cross fork assembly 2 is fixed to the fork plate by a second locking bolt 34, and a bearing 33 is provided between the second locking bolt 34 and the fork plate.

[0057] The central pressing block 23 can be fixed between the central cross fork assembly 2 and the torsion bar assembly 22 by means of a second locking bolt 34 .

[0058] The bearing 33 is a deep groove ball bearing.

[0059] An adjustment pad 24 is provided between the central cross fork assembly 2 and the fork piece, one side of the adjustment pad 24 contacts the central cross fork assembly 2, and the other end of the adjustment pad 24 contacts the fork piece.

[0060] Embodiment 4:

[0061] See also Figures 2 to 3 In order to optimize the assembly performance between the blade arm assembly 1 and the center cross fork assembly 2, based on the above embodiment: the blade arm assembly 1 is sleeved on the center cross fork assembly 2, and a self-lubricating bushing 26 is provided between the blade arm assembly 1 and the center cross fork assembly 2.

[0062] A retaining ring 25 is provided between one end of the self-lubricating bushing 26 close to the hub fork assembly 3 and the center cross fork assembly 2 .

[0063] The following further describes a twist strip assembly type helicopter tail rotor hub provided by the present invention in combination with the working principle:

[0064] The tail rotor of a helicopter undergoes the following movements during normal operation. Assuming that the plane perpendicular to the axis of the output shaft is taken as the reference plane, the tail rotor blade arm assembly and the cross fork assembly as a whole rotate around the axis of the output shaft within the reference plane, the cross fork assembly at the center of the tail rotor as a whole swings up and down relative to the reference plane, and the tail rotor arm assembly performs a third movement of blade pitch change around each pitch change axis. The above three movements are the follow-up movements of the tail rotor hub after releasing the degrees of freedom in various directions.

[0065] Therefore, the tail rotor hub of the helicopter should meet the requirements of the above-mentioned rotation, flapping and pitch change movements of the blades. It adopts a torsion bar assembly design to withstand the centrifugal force of the tail rotor blades when they rotate, while releasing the degrees of freedom of the tail rotor blades in the pitch change direction. The bearingless design reduces the overall size and mass of the hub structure.

[0066] The use of a torsion strip assembly instead of the bearing design eliminates the lubrication system design of the internal bearing, reducing the risk of lubricating oil leaking and contaminating the tail rotor blades under the action of centrifugal force, keeping the tail rotor hub and blade surface clean, and reducing maintenance costs.

[0067] By using torsion bar assemblies instead of bearings, the hub has a lighter overall mass, a relatively longer service life, easier maintenance, and lower manufacturing and use costs.

[0068] The present invention is not limited to the above optional implementation modes. Under the premise of not conflicting with each other, the various schemes can be combined arbitrarily. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in their shapes or structures, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A twist strip type helicopter tail rotor hub, characterized in that: It includes a center cross fork assembly mounted on the hub fork assembly, and a blade arm assembly is mounted on the center cross fork assembly; The blade support arm assembly is fixed to the central cross fork assembly through a torsion bar assembly; The hub fork assembly is mounted on the output shaft, and the center cross fork assembly is rotatably connected to the hub fork assembly around a rotation axis perpendicular to the axis of the output shaft; There are two blade arm assemblies, and the two blade arm assemblies are symmetrically arranged about the central cross fork assembly. One end of the torsion bar assembly is connected to one of the blade arm assemblies, and the other end of the torsion bar assembly is connected to the other blade arm assembly. A central pressing block for fixing the torsion bar assembly is arranged inside the central cross assembly, and the distances from both ends of the torsion bar assembly to the central pressing block are equal; The pull-twist strip assembly includes at least two metal strips stacked together; The torsion bar assembly is fixed to the blade support arm assembly by a first locking bolt, an inner fixing bushing for fixing the torsion bar assembly is arranged on a side of the first locking bolt close to the center cross fork assembly, and an outer fixing bushing for fixing the torsion bar assembly is arranged on a side of the first locking bolt away from the inner fixing bushing; The inner fixing bushing and the outer fixing bushing are both fixed by the first locking bolt; A vibration-damping rubber pad is provided between the propeller hub fork assembly and the output shaft; The propeller hub fork assembly includes a propeller hub fork arranged on the output shaft, and the propeller hub fork is provided with two fork pieces for fixing the central cross fork assembly, and the central cross fork assembly is fixed to the fork piece by a second locking bolt, and a bearing is provided between the second locking bolt and the fork piece; The bearing is a deep groove ball bearing; An adjustment pad is arranged between the central cross fork assembly and the fork piece, one side of the adjustment pad is in contact with the central cross fork assembly, and the other end of the adjustment pad is in contact with the fork piece.

2. The twist strip type helicopter tail rotor hub according to claim 1, characterized in that: The blade support arm assembly is sleeved on the central cross fork assembly, and a self-lubricating bushing is arranged between the blade support arm assembly and the central cross fork assembly.

3. The twist strip type helicopter tail rotor hub according to claim 2, characterized in that: A retaining ring is arranged between one end of the self-lubricating bushing close to the hub fork assembly and the center cross fork assembly.

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