WO2017143365A1

WO2017143365A1 - Multicopter frame

Info

Publication number: WO2017143365A1
Application number: PCT/AM2017/000001
Authority: WO
Inventors: Garik GEVORGYAN
Original assignee: HARUTYUNYAN, Hayk
Priority date: 2016-02-26
Filing date: 2017-02-22
Publication date: 2017-08-31

Abstract

A simple, lightweight, strong and rigid frame of multicopter comprising a central hub, a plurality of compression and a plurality of tension members attached to one another, forming altogether a three-dimensional polytope type shape. The tension members are pre-tensed to fix the position of the compression members and reinforce the frame. The compressive and tensile forces occurring in such frame are in equilibrium, and deformation forces applying to the frame during the operation of the aircraft are distributed among the compression and tension members and compensated by reactive tensile and compressive forces occurring therein. The tension members may be of adjustable length (e.g. spokes with nipples) for adjusting their tension and truing the frame.

Description

Multicopter frame

Technical Field

The invention relates to flying apparatuses, more particularly to multirotor aircraft often referred to as multicopters, and more particularly to their frames.

Background Art

Due to simplicity of construction and control with the ability to ascent and descent vertically, move horizontally in any direction, rapidly change the flight direction or stop and hover in the air, multicopters are becoming increasingly popular in various fields. Multicopters have two or more rotors mounted on a rigid frame which has no aerodynamic significance. Some typical configurations are referred to as "tricopters," "quadcopters," "hexacopters" and "octocopters" to reflect the number of rotors powering them (3, 4, 6 and 8, respectively), and as Y-, X- and H- shaped to reflect the shape of their frames. Typically, the control unit, the energy source and possibly also some payload (e.g. a camera or a delivery item), are mounted in or attached to a central hub of the load-bearing frame of the aircraft, and the rotors are mounted on the periphery of the frame. In certain configurations some rotors are mounted on the central hub or interior part of the load-bearing frame.

Structural integrity, strength, rigidity, weight, susceptibility to vibration and aerodynamic characteristics are important factors affecting performance of multicopters.

There are known structures of multicopter frames, where the frame comprise a central hub, rigid arms are attached to and radially extend from such central hub, and rotors are mounted at the outer ends of arms (see, for example, US2015069174, US2014131510, US2012083945 or US2009008499).

Known are structures of multicopter frames, where the rigid arms can be folded for compact storage and transportation (see, for example, US3053480 or US2014339355).

Known are also structures of multicopter frames, where the rigid arms can be easily disassembled and assembled for convenient storage and transportation, as well as ease of maintenance (see, for example, US2009283629).

In the prior art referred to above, arms should be able to withstand bending stress.

The main deficiency of the prior art is that insufficient strength and rigidity of the frame has an adverse effect on the manageability, manoeuvrability, flight stability and structural integrity of the multicopter, and improvement of strength and rigidity of the frame result in increased weight, aerodynamic impact and/or cost. These issues are even more severe in larger multicopters and multicopters having larger number of rotors.

In the closest prior art disclosed in US3889902, a tubular trussed structure is used for the frame of the multicopter. However, it is characterized by heavy weight, as the mentioned trussed structure entirely consists of members which are made of material resistant to both compressive and tensile stresses and are relatively heavy.

Summary of Invention

It is a purpose of the present invention to provide a novel load-bearing frame for multirotor aircraft advantageously characterized by light weight, high strength, high rigidity, structural integrity, minimum aerodynamic impact, simplicity of construction and cost efficiency in terms of manufacturing, operation and maintenance.

Another purpose of this invention is to provide such frame which is easy to assemble and disassemble. Still another purpose of this invention is to provide such frame which, when disassembled, is compact. A further purpose of this invention is to provide such frame which can be sold as an assembly kit.

Another purpose of this invention is to provide such frame which can be constructed using readily available components (such as, for instance, bicycle wheel-spokes and nipples, tubes or bars made of metal, wood or composite materials).

The foregoing objective of the present invention is attained by a structure comprising a central hub, a plurality of compression and a plurality of tension members attached to one another, forming altogether a three-dimensional polytope type shape. Rotors are mounted at the outer vertices of the frame.

The tension members are pre-tensed to fix the position of the compression members in respect of each other and the central hub, as well as to reinforce the frame. The compressive and tensile forces occurring in the frame are brought into equilibrium, and deformation forces applying to the frame during the operation of the aircraft are distributed among the compression and tension members and the central hub, and are compensated by reactive tensile and compressive forces occurring therein. Use of thin and lightweight tension members, as well as relatively thin and lightweight compression members, gives the possibility of significantly reducing the weight and aerodynamic impact of the frame, while ensuring its high strength and rigidity.

Solid bars or hollow tubes of round, polygonal or other shape can be used as compression elements.

Tension spokes or tension strings can be used as tension members. Tension members of adjustable length (such as, for instance, bicycle wheel spokes with nipples screwed at one end) can be used for having the possibility of adjusting the compressive and tensile forces in the frame and truing the frame.

Hinge type connections can be used to enable compact transportation and storage of the multicopter.

Connections that allow easy assembly and disassembly of the frame can be used to enable ease of maintenance, as well as compact transportation and storage of the multicopter.

The present invention will be readily understood upon consideration of the detailed description of certain preferred embodiments thereof in conjunction with the accompanying drawings.

Brief Description of Drawines

Fig. 1 shows a quadcopter frame with compression members radially extending from a central hub.

Fig. 2 is a fragment of Fig. 1 showing the connection of the tension spokes to the outer ends of the compression members and the central hub.

Fig. 3 shows a fragment of a quadcopter frame, in which tension strings are used instead of tension spokes.

Fig. 4 shows options for strengthening the frame shown in Fig 1.

Fig. 5 shows a star-shaped quadcopter frame.

Fig. 6 shows a hexacopter frame with peripheral disposition of compression members.

Description of Embodiments

In one preferred embodiment of the present invention for a quadcopter, as presented in Fig. 1 , four coplanar tubes (1) made of material resistant to compressive stress are attached to and radially extend from central hub (2) made of material resistant to both compressive and tensile stresses. Flanges (6) are mounted at the outer ends of tubes (1). Spokes (3) and (4) made of material resistant to tensile stress tie opposite parts of flanges (6) with opposite parts of hub (2), forming two coplanar polygon type shapes which are perpendicular to the plane of tubes (1). Flanges (6) are consecutively tied to one another by spokes (5) made of material resistant to tensile stress. As illustrated in the detailed view in Fig. 2, a nipple (7) is screwed at one end of each spoke (3), (4) and (5) for adjusting the tension of such spokes and truing the frame. Rotors (8) are mounted at the outer ends of tubes (2). The control unit, the energy source of the aircraft and possibly also some payload (not shown in the drawing) can be enclosed in or attached to the central hub.

In an alternative embodiment illustrated in Fig. 3, strings (9), (10) and (11) with rivets (12) at both ends of each string are used instead of the above mentioned spokes with nipples; such strings being fixed in respective slots of flange (13) and central hub (14).

To make the frame more rigid against rotational torque around the vertical axis, radial spokes 4 of the quadcopter frame depicted in Fig. 1 may be replaced by tangential spokes 4a and 4b shown by dotted lines in Fig. 4.

In another preferred embodiment of this claim, in the quadcopter described above, each tube may be attached to the central hub by a hinge (not shown in the drawing), so that after detaching the spokes the frame could be compactly stowed for transportation or storage.

In another preferred embodiment of the present invention for a quadcopter, as presented in Fig.

5, two non-coplanar tubes (15) made of material resistant to compressive stress extend between diagonally opposite ends , of the frame crossing through central hub (16) made of material resistant to tensile stress. Three spokes (17a), (17b) and (18) made of material resistant to tensile stress are attached to flanges (19), on one side, and central hub (16), on the other side. Spokes (17a), (17b) and (18) are pre-tensioned by nipples (20) to create balanced tensile and compressive forces in spokes (17a), (17b) and (18) and tubes (15) and reinforce the frame.

In another preferred embodiment of the present invention for a hexacopter, as presented in Fig.

6, six coplanar tubes (21) made of material resistant to compressive stress are attached to one another forming a polygon surrounding central hub (22) made of material resistant to tensile stress. Connecting members (23) are used for attaching tubes (21) to one another. The same connecting members (23) can be used as platforms for mounting the rotors of the aircraft (not shown in the drawing). Spokes (24a), (24b), (25a) and (25b) made of material resistant to tensile stress tie connecting members (23) to the upper and lower parts of central hub (22) forming a three-dimensional polytope. Spokes (24a), (24b), (25a) and (25b) are pre-tensioned by nipples (26) to create balanced tensile and compressive forces in spokes (24a), (24b), (25a) and (25b) and tubes (21) and reinforce the frame.

Reference Materials 1. US2015069174, IPC B64C 25/06, published on 12/03/2015;

2. US2014131510, IPC B64C 27/06, published on 15/05/2014;

3. US2012083945, IPC B64C 27/08, published on 05/04/2012;

4. US2009008499, IPC B64C 27/08, published on 08/01/2009;

5. US2009283629, IPC B64C 27/08, published on 19/11/2009;

6. US3053480, IPC B64C 27/54, published on 11/09/1962;

7. US2014339355, IPC B64C 27/08, published on 20/11/2014;

8. US3889902, IPC B64C 27/04, published on 17/06/1975 ~ the closest prior art

Claims

1. A multicopter frame comprising a central component and a peripheral component, characterized in that the peripheral component comprises a plurality of coplanar compression members and a plurality of tension members, one end of each compression member is attached to the central component, the compression members extend radially from the central component, the outer ends of the compression members are sequentially tied by tension members to one another and are also tied by tension members to at least one point on the central which is higher than the plane of the compression members and at least one point on the central which is lower than the plane of the compression members, the tension members are pre-tensed to create balanced tensile and compressive forces in the tension and compression members.

2. A multicopter frame as set forth in claim 1, characterized in that the compression members are attached to the central component by hinge-type connections.

3. A multicopter frame as set forth in claim 1, characterized in that the central component and the compression members comprise integral parts of a single object.

4. A multicopter frame as set forth in claims 1 to 3, characterized in that the tension members are made in form of spokes with nipples, and tension of which is regulated by nipples.

5. A multicopter frame as set forth in claims 1 to 3, characterized in that the tension members are made in form of strings.

6. A multicopter frame as set forth in claims 1 to 5, characterized in that the type of connections used in the frame allow it be easily assembled and disassembled.

7. A multicopter frame comprising a central component and a peripheral component, characterized in that the peripheral component comprises a plurality of compression and a plurality of tension members, one end of each compression member is attached to the central component, the compression members extend radially from the central component, the outer end of each compression member is tied to the central component by at least three tension members which form a pyramid like shake surrounding such compression member, the tension members are pre-tensed to create balanced tensile and compressive forces in the tension and compression members.

8. A multicopter frame as set forth in claim 7, characterized in that the compression members are attached to the central component by hinge-type connections.

9. A multicopter frame as set forth in claim 7, characterized in that the central component and the compression members comprise integral parts of a single object.

10. A multicopter frame as set forth in claims 7 to 9, characterized in that the tension members are made in form of spokes with nipples, and tension of spokes is regulated by nipples.

11. A multicopter frame as set forth in claims 7 to 9, characterized in that the tension members are made in form of strings.

12. A multicopter frame as set forth in claims 7 to 11, characterized in that the type of connections used in the frame allow it be easily assembled and disassembled.

13. A multicopter frame comprising a central component and a peripheral component, characterized in that the peripheral component comprises a plurality of coplanar compression and a plurality of tension members, the compression members are sequentially attached to one another forming a polygon type shape surrounding the central component, each vertex of such polygo is tied by tension members to at least one point on the central which is higher than the plane of the polygon and at least one point on the central which is lower than the plane of the polygon, the tension members are pre-tensed to create balanced tensile and compressive forces in the tension and compression members.

14. A multicopter frame as set forth in claim 13, characterized in that the compression members comprise integral parts of a single object.

15. A multicopter frame as set forth in claims 13 to 14, characterized in that the tension members are made in form of spokes with nipples, and tension of spokes is regulated by nipples.

16. A multicopter frame as set forth in claims 13 to , 14, characterized in that the tension members are made in form of strings.

17. A multicopter frame as set forth in claims 13, 15 and 16, characterized in that the type of connections used in the frame allow it be easily assembled and disassembled.