CN106741860B - Oil-driven multi-rotor flexible rotor system based on composite material - Google Patents
Oil-driven multi-rotor flexible rotor system based on composite material Download PDFInfo
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- CN106741860B CN106741860B CN201611265381.1A CN201611265381A CN106741860B CN 106741860 B CN106741860 B CN 106741860B CN 201611265381 A CN201611265381 A CN 201611265381A CN 106741860 B CN106741860 B CN 106741860B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
- B64C11/30—Blade pitch-changing mechanisms
- B64C11/32—Blade pitch-changing mechanisms mechanical
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- Mechanical Engineering (AREA)
- Aviation & Aerospace Engineering (AREA)
- Pivots And Pivotal Connections (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses an oil-driven multi-rotor flexible rotor wing system based on a composite material, which comprises a rotor hub system and a pitch-changing system. The positional connection relationship between them is: the pitch-changing system is sleeved on a main shaft in the hub system. The invention solves the problems of complex structure, large mass, high processing precision requirement, large assembly difficulty and the like of the existing oil-driven multi-rotor helicopter rotor system. The rotor hub system has no bearing component, and only the reasonable layering of the composite material tension-torsion strips is used for completing various functions of the rotor system, so that the rotor hub system has the advantages of small weight, simple structure, easiness in assembly and good reliability and maintainability.
Description
Technical Field
The invention relates to the technical field of aviation, in particular to an oil-driven multi-rotor flexible rotor system based on a composite material.
Technical Field
Compared with an electric direct-drive multi-rotor helicopter, the oil-driven multi-rotor helicopter has the characteristics of long endurance time, strong loading capacity, long range and the like, and is increasingly applied to the national economy field. The main current oil-driven multi-rotor helicopter rotor system mainly comprises rotors and a pitch-changing mechanism, and the oil-driven multi-rotor pitch-changing mechanism only needs to realize total pitch control. A variable-pitch system for an oil-powered multi-rotor aircraft has been described in chinese patent specification CN-105857578-a (2016.08.17 of application publication), which comprises a main shaft on which a rotor head is fixed, the rotor head and rotor clamp being coupled by means of pressure bearings and positioning bearings; there is the displacement axle in the main shaft, and the displacement axle stretches out from the top of rotor head, and the top of displacement axle is fixed with the displacement shift fork, and the upper end of two displacement pull rods is connected through the round pin axle with the both ends of displacement shift fork respectively, and the lower extreme of two displacement pull rods is connected with two rotor clamp respectively, is equipped with the copper sheathing between the pore wall of displacement axle and rotor head, is equipped with the sealing washer between rotor head pore wall and the displacement axle of going up copper sheathing top. A lower copper sleeve is arranged between the distance-changing shaft and the bottom of the main shaft, and a lower sealing ring is arranged between the main shaft below the lower copper sleeve and the distance-changing shaft. The variable-pitch mechanism comprises a sealing device, a variable-pitch bearing, a variable-pitch shaft and other parts, and has the defects of complex structure, high quality, high processing precision requirement and high assembly difficulty.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides an oil-driven multi-rotor flexible rotor system based on a composite material. The rotor hub system has no bearing component, and only the reasonable layering of the composite material tension-torsion strips is used for completing various functions of the rotor system, so that the rotor hub system has the advantages of small weight, simple structure, easiness in assembly and good reliability and maintainability.
The technical scheme adopted by the invention is as follows: a composite-based oil-driven multi-rotor flexible rotor system comprises a rotor hub system and a pitch-changing system. The positional connection relationship between them is: the pitch-changing system is sleeved on a main shaft in the hub system.
The hub system comprises blades, a pitch-changing rocker arm, composite material tension-torsion bars, rotor wing cushion blocks, hubs and a main shaft. The paddle is fixedly connected with the pitch-changing rocker arm, and the pitch-changing rocker arm is respectively fixedly connected with the two composite material tension torsion bars and is arranged between the two composite material tension torsion bars; the rotor wing cushion blocks are respectively and fixedly connected with the two composite material tension torsion bars and are arranged between the two tension torsion bars to play a supporting role; the upper end of the propeller hub is fixedly connected with the composite material tension torsion bar and the rotor cushion block, and the lower end of the propeller hub is fixedly connected with the main shaft sleeve; the main shaft extends out of the oil-driven multi-rotor speed reducer.
The distance changing system comprises a distance changing pull rod, a distance changing shifting fork, a sliding ring gland, an inner sliding ring, a sliding ring bearing, an outer sliding ring, a total distance pull rod, a total distance bearing and a total distance shifting fork. The two ends of the variable-pitch pull rod are respectively provided with a spherical groove, the grooves at the upper end are sleeved with the ball structures at the tail ends of the variable-pitch rocker arms in the propeller hub system, and the grooves at the lower end are sleeved with the ball structures on the slip ring pressing cover; one end of the variable-pitch shifting fork is fixedly connected with a propeller hub in a propeller hub system, and a fork-shaped structure at the other end is sleeved with a variable-pitch pull rod; the slip ring gland is fixedly connected with the inner slip ring, and the inner slip ring is sleeved on the main shaft and can axially move along the main shaft; the inner ring of the slip ring bearing is fixedly connected with the inner slip ring, the outer ring is fixedly connected with the outer slip ring, and the slip ring bearing is used for supporting the inner slip ring and the outer slip ring and allowing the inner slip ring and the outer slip ring to rotate relatively; spherical grooves are formed in the two ends of the total distance pull rod, the upper end of the total distance pull rod is sleeved with a ball head structure of the outer slip ring, and the lower end of the total distance pull rod is sleeved with a ball head of a rocker arm of the variable-distance steering engine; the inner ring of the total distance bearing is fixedly connected with the main shaft, and the outer ring of the total distance bearing is fixedly connected with the total distance shifting fork and is used for supporting the total distance shifting fork and the main shaft and allowing the total distance shifting fork and the main shaft to rotate relatively; the total distance pull rod is sleeved in the fork-shaped structure; the collective shifting fork is fixedly connected with the oil-driven multi-rotor speed reducer.
The advantages and the effects are as follows: compared with the prior art, the invention has the beneficial effects of solving the problems of complex structure, large mass, high processing precision requirement, large assembly difficulty and the like of the existing oil-driven multi-rotor helicopter rotor system. The rotor hub system has no bearing component, and only the reasonable layering of the composite material tension-torsion strips is used for completing various functions of the rotor system, so that the rotor hub system has the advantages of small weight, simple structure, easiness in assembly and good reliability and maintainability.
Drawings
FIG. 1 is a schematic diagram of a composite-based oil-actuated multi-rotor flexible rotor system;
figure 2 is a cross-sectional view of a composite-based oil-powered multi-rotor flexible rotor system;
figure 3 is a top view of the structure of a composite-based oil-powered multi-rotor flexible rotor system;
the symbols in the figures are as follows:
1-a paddle; 2-a composite material pulling and twisting strip; 3-pitch-changing rocker arms; 4-rotor cushion blocks; 5-a hub; 6-a main shaft; 7-a variable-pitch pull rod; 8-a variable-pitch shifting fork; 9-a slip ring gland; 10-an inner slip ring; 11-slip ring bearings; 12-an outer slip ring; 13-total distance pull rod; 14-total distance bearing; 15-total distance shifting fork.
Detailed Description
The preferred embodiments of the present invention will be described with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
In order to overcome the defects in the prior art, the invention provides an oil-driven multi-rotor flexible rotor wing system based on a composite material.
Referring to fig. 1, the hub system associated with the composite-based oil-actuated multi-rotor flexible rotor system of the present embodiment is mainly constructed as follows: the hub system comprises a blade 1, a composite material tension torsion bar 2, a pitch-changing rocker arm 3, a rotor cushion block 4, a hub 5 and a main shaft 6. The paddle 1 is fixedly connected with the pitch-changing rocker arm 3, and the pitch-changing rocker arm 3 is fixedly connected with the two composite material tension-torsion bars 2 respectively and is arranged between the two; the rotor wing cushion blocks 4 are respectively fixedly connected with the two composite material tension torsion bars 2 and are arranged between the two tension torsion bars to play a supporting role; the upper end of the propeller hub 5 is fixedly connected with the composite material tension torsion bar 2 and the rotor cushion block 4, and the lower end is sleeved and fixedly connected with the main shaft 6; the main shaft 6 extends from the oil-driven multi-rotor speed reducer.
Referring to fig. 1-3, the pitch system associated with the composite-based oil-powered multi-rotor flexible rotor system of the present embodiment is mainly constructed as follows: the distance changing system comprises a distance changing pull rod 7, a distance changing shifting fork 8, a slip ring gland 9, an inner slip ring 10, a slip ring bearing 11, an outer slip ring 12, a total distance pull rod 13, a total distance bearing 14 and a total distance shifting fork 15. Spherical grooves are formed at two ends of the variable-pitch pull rod 7, the grooves at the upper end are sleeved with the ball head structures at the tail end of the variable-pitch rocker arm 3 in the propeller hub system, and the grooves at the lower end are sleeved with the ball head structures on the slip ring gland 9; one end of the variable-pitch shifting fork 8 is fixedly connected with a propeller hub 5 in a propeller hub system, and a fork-shaped structure at the other end is sleeved with a variable-pitch pull rod 7; the slip ring gland 9 is fixedly connected with the inner slip ring 10, and the inner slip ring 10 is sleeved on the main shaft 6 and can axially move along the main shaft 6; the inner ring of the slip ring bearing 11 is fixedly connected with the inner slip ring, the outer ring is fixedly connected with the outer slip ring 12, and the slip ring bearing is used for supporting the inner slip ring 10 and the outer slip ring 12 and allowing the inner slip ring 10 and the outer slip ring 12 to rotate relatively; spherical grooves are formed at two ends of the total distance pull rod 13, the upper end of the total distance pull rod is sleeved with a ball head structure of the outer slip ring 12, and the lower end of the total distance pull rod is sleeved with a ball head of a rocker arm of the variable-distance steering engine; the inner ring of the collective bearing 14 is fixedly connected with the main shaft 6, and the outer ring is fixedly connected with the collective shifting fork 15 and is used for supporting the collective shifting fork 15 and the main shaft 6 and allowing the collective shifting fork 15 and the main shaft 6 to rotate relatively; the collective pitch pull rod 13 is sleeved into the fork-shaped structure; the collective shifting fork 15 is fixedly connected with the oil-driven multi-rotor speed reducer.
Referring to fig. 1 to 3, the specific operation procedure of this embodiment is as follows:
the main shaft 6 rotates under the action of a speed reducer, the hub 5, the composite material tension torsion bar 2, the rotor cushion block 4, the blade 1 and the pitch-variable rocker arm 3 which are directly or indirectly connected with the main shaft rotate together with the main shaft 6 at the same rotating speed, the blade 1 rotates, and the rotor system generates a pulling force along the axial direction of the main shaft 6; the distance-changing rocker arm 3 rotates to drive the upper end of the distance-changing pull rod 7 to rotate, the distance-changing shifting fork 8 rotates to shift the middle part of the distance-changing pull rod 7 to rotate, and the slip ring gland 9 and the distance-changing pull rod 7 rotate at the same speed under the combined action of the two; the collective shifting fork 15 is fixedly connected with the speed reducer, and in a fixed state, the collective pull rod 13 sleeved in the collective shifting fork 15 does not rotate under the action of the shifting fork structure, but can do linear motion along the axial direction of the main shaft 6, and the outer slip ring 12 connected with the upper end of the collective pull rod 13 also does not rotate.
When the oil-driven multi-rotor wing performs maneuvering action, the distance-changing steering engine rocker rotates and drives the total distance pull rod 13 to do linear motion along the axis direction of the main shaft, and the outer slip ring 12 connected with the upper end of the distance-changing pull rod 13 moves along the same direction; the outer slip ring 12 drives the inner slip ring 10 and the slip ring gland 9 to move together through the slip ring bearing 11, and at the moment, the slip ring gland 9 rotates together with the main shaft 6 and moves linearly along the axial direction of the main shaft 6; the distance-changing pull rod 7 also moves linearly along the axial direction of the main shaft 6 under the action of the slip ring gland, and transmits the force on the distance-changing pull rod 7 to the distance-changing rocker arm 3; the composite material tension torsion bar 2 is in a bending torsion combined beam configuration, and can bear larger tension and is easy to twist through reasonable design of composite material layering; the pitch-changing rocker arm 3 is forced to drive the two ends of the composite material tension torsion bar 2 to twist, the pitch of the blade 1 fixedly connected with the pitch-changing rocker arm 3 is changed, and the tension of the rotor system is changed. The rotor aerodynamics can know that the blade 1 can generate waving motion in the rotating process, two composite material pull torsion strips 2 are clamped on the blade 1, the middle of the composite material pull torsion strips are supported by the rotor cushion block 4, the structure is favorable for waving motion, and the influence of waving moment on the oil-driven multi-rotor body is weakened.
Claims (1)
1. An oil moves flexible rotor system of many rotors based on combined material, its characterized in that: the device comprises a paddle hub system and a variable-pitch system; the positional connection relationship between them is: the pitch-changing system is sleeved on a main shaft in the hub system;
the rotor hub system comprises a blade (1), a composite material tension-torsion bar (2), a pitch-changing rocker arm (3), a rotor wing cushion block (4), a rotor hub (5) and a main shaft (6); the blade (1) is fixedly connected with the pitch-variable rocker arm (3), and the pitch-variable rocker arm (3) is fixedly connected with the two composite material tension-torsion bars (2) respectively and is arranged between the two composite material tension-torsion bars; the rotor wing cushion block (4) is fixedly connected with the two composite material tension torsion bars (2) respectively and is arranged between the two tension torsion bars to play a supporting role; the upper end of the propeller hub (5) is fixedly connected with the composite material tension torsion bar (2) and the rotor wing cushion block (4), and the lower end is sleeved and fixedly connected with the main shaft (6); the main shaft (6) extends out of the oil-driven multi-rotor speed reducer;
the variable-pitch system comprises a variable-pitch pull rod (7), a variable-pitch shifting fork (8), a slip ring gland (9), an inner slip ring (10), a slip ring bearing (11), an outer slip ring (12), a total-pitch pull rod (13), a total-pitch bearing (14) and a total-pitch shifting fork (15); spherical grooves are formed in two ends of the variable-pitch pull rod (7), the grooves at the upper end are sleeved with ball structures at the tail end of the variable-pitch rocker arm (3) in the propeller hub system, and the grooves at the lower end are sleeved with ball structures on the slip ring gland (9); one end of a variable-pitch shifting fork (8) is fixedly connected with a propeller hub (5) in a propeller hub system, and a fork-shaped structure at the other end is sleeved with a variable-pitch pull rod (7); the slip ring gland (9) is fixedly connected with the inner slip ring (10), and the inner slip ring (10) is sleeved on the main shaft (6) and can axially move along the main shaft (6); the inner ring of the slip ring bearing (11) is fixedly connected with the inner slip ring, the outer ring is fixedly connected with the outer slip ring (12), and the slip ring bearing is used for supporting the inner slip ring (10) and the outer slip ring (12) and allowing the inner slip ring and the outer slip ring to rotate relatively; spherical grooves are processed at two ends of the total distance pull rod (13), the upper end of the total distance pull rod is sleeved with a ball head structure of the outer slip ring (12), and the lower end of the total distance pull rod is sleeved with a ball head of a rocker arm of the variable-distance steering engine; the inner ring of the total distance bearing (14) is fixedly connected with the main shaft (6), and the outer ring is fixedly connected with the total distance shifting fork (15) and is used for supporting the total distance shifting fork (15) and the main shaft (6) and allowing the total distance shifting fork and the main shaft (6) to rotate relatively; the total distance pull rod (13) is sleeved in the fork-shaped structure; the collective shifting fork (15) is fixedly connected with the oil-driven multi-rotor speed reducer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611265381.1A CN106741860B (en) | 2016-12-30 | 2016-12-30 | Oil-driven multi-rotor flexible rotor system based on composite material |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201611265381.1A CN106741860B (en) | 2016-12-30 | 2016-12-30 | Oil-driven multi-rotor flexible rotor system based on composite material |
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| Publication Number | Publication Date |
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| CN106741860A CN106741860A (en) | 2017-05-31 |
| CN106741860B true CN106741860B (en) | 2023-09-29 |
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| CN201611265381.1A Active CN106741860B (en) | 2016-12-30 | 2016-12-30 | Oil-driven multi-rotor flexible rotor system based on composite material |
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Families Citing this family (4)
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| CN108341054B (en) * | 2018-04-27 | 2023-05-02 | 安徽工程大学 | Unmanned aerial vehicle rotor cutting angle adjustment mechanism |
| CN109774919A (en) * | 2018-11-06 | 2019-05-21 | 珠海隆华直升机科技有限公司 | High-torque pull rod transmission system and helicopter |
| CN112224404A (en) * | 2020-10-16 | 2021-01-15 | 中国直升机设计研究所 | Oversleeve structure for foldable bearingless rotor wing |
| CN112389636B (en) * | 2020-11-10 | 2022-12-09 | 成都云尘科技有限责任公司 | Built-in integral type propeller hub and control method |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB569867A (en) * | 1943-12-08 | 1945-06-12 | Nicholas Straussler | Improvements in variable pitch propellers |
| GB850037A (en) * | 1958-06-05 | 1960-09-28 | Rolls Royce | Improvements in or relating to control mechanisms for variable-pitch propellers |
| CN101318552A (en) * | 2007-05-24 | 2008-12-10 | 尤洛考普特公司 | Hydraulic dispenser equipped with a device for detecting seizures |
| CN104129498A (en) * | 2014-07-23 | 2014-11-05 | 中国航天空气动力技术研究院 | Rotor wing control mechanism for coaxial helicopter |
| CN205060011U (en) * | 2015-10-27 | 2016-03-02 | 中航维拓（北京）科技有限责任公司 | Oil moves four rotor unmanned aerial vehicle rotor - control system of displacement |
| CN205589477U (en) * | 2016-05-05 | 2016-09-21 | 武汉捷特航空科技有限公司 | Unmanned helicopter rotor head |
| CN205707301U (en) * | 2016-04-20 | 2016-11-23 | 程靖 | A kind of pulp distance varying mechanism |
| CN205738063U (en) * | 2016-05-20 | 2016-11-30 | 辽宁辽飞航空科技有限公司 | The dynamic multi-rotor aerocraft displacement system of a kind of oil |
| CN206358352U (en) * | 2016-12-30 | 2017-07-28 | 中航维拓（天津）科技有限公司 | A kind of oil based on composite moves many rotor flexible rotor systems |
-
2016
- 2016-12-30 CN CN201611265381.1A patent/CN106741860B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB569867A (en) * | 1943-12-08 | 1945-06-12 | Nicholas Straussler | Improvements in variable pitch propellers |
| GB850037A (en) * | 1958-06-05 | 1960-09-28 | Rolls Royce | Improvements in or relating to control mechanisms for variable-pitch propellers |
| CN101318552A (en) * | 2007-05-24 | 2008-12-10 | 尤洛考普特公司 | Hydraulic dispenser equipped with a device for detecting seizures |
| CN104129498A (en) * | 2014-07-23 | 2014-11-05 | 中国航天空气动力技术研究院 | Rotor wing control mechanism for coaxial helicopter |
| CN205060011U (en) * | 2015-10-27 | 2016-03-02 | 中航维拓（北京）科技有限责任公司 | Oil moves four rotor unmanned aerial vehicle rotor - control system of displacement |
| CN205707301U (en) * | 2016-04-20 | 2016-11-23 | 程靖 | A kind of pulp distance varying mechanism |
| CN205589477U (en) * | 2016-05-05 | 2016-09-21 | 武汉捷特航空科技有限公司 | Unmanned helicopter rotor head |
| CN205738063U (en) * | 2016-05-20 | 2016-11-30 | 辽宁辽飞航空科技有限公司 | The dynamic multi-rotor aerocraft displacement system of a kind of oil |
| CN206358352U (en) * | 2016-12-30 | 2017-07-28 | 中航维拓（天津）科技有限公司 | A kind of oil based on composite moves many rotor flexible rotor systems |
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Effective date of registration: 20230516 Address after: 402247 No. 390, north section of Nanbei Avenue, Shuangfu street, Jiangjin District, Chongqing Applicant after: Chongqing Camel Aviation Technology Co.,Ltd. Address before: 300300 Building B, No. 3 Tengfei Road, Junliangcheng Industrial Park, Dongli District, Tianjin City Applicant before: AVIC WEITUO (TIANJIN) TECHNOLOGY CO.,LTD. |
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