阅读说明：本技术 电缆以及具备该电缆的连接结构体、布线及系泊型移动体 (Cable, connection structure provided with same, wiring, and mooring type mobile unit ) 是由 金子洋 于 2019-09-26 设计创作，主要内容包括：本发明的目的在于提供可以实现电缆整体的重量的轻质化的电缆等,所述电缆用于至少进行系泊型移动体的系泊及供电。本发明的电缆(1)为下述电缆,其用于将系泊型移动体(2)连接于包含电源单元(5)的集合单元(6)而至少进行系泊型移动体向集合单元的系泊、以及从电源单元向系泊型移动体的供电,其中,构成电缆的导体的线束的至少一部分为高强度铝系导体。(The purpose of the present invention is to provide a cable or the like that can achieve weight reduction of the entire cable used for mooring and power supply of at least a mooring type mobile unit. The cable (1) is used for connecting a mooring type moving body (2) to a collective unit (6) including a power supply unit (5) so as to perform at least mooring of the mooring type moving body to the collective unit and power supply from the power supply unit to the mooring type moving body, wherein at least a part of a harness constituting a conductor of the cable is a high-strength aluminum conductor.)

1. A cable for connecting a mooring type mobile unit to a collective unit including a power supply unit, and mooring the mooring type mobile unit to the collective unit and supplying power from the power supply unit to the mooring type mobile unit,

at least a part of a wire harness constituting a conductor of the cable is a high-strength aluminum-based conductor.

2. The cable according to claim 1, wherein the tensile strength of the high-strength aluminum-based conductor is 180MPa or more.

3. The cable according to claim 1 or 2, wherein the high-strength aluminum-based conductor is formed of 8000-series aluminum alloy.

4. The cable according to claim 1 or 2, wherein the high-strength aluminum-based conductor is formed of a 5000-series aluminum alloy.

5. The cable according to claim 1 or 2, wherein the high-strength aluminum-based conductor is formed of 6000-series aluminum alloy.

6. The cable according to any one of claims 1 to 5, wherein the high-strength aluminum-based conductor has a fibrous metal structure in which crystal grains extend along an extending direction of the high-strength aluminum-based conductor in parallel, and an average value of a dimension of the crystal grains perpendicular to a longitudinal direction in a cross section parallel to the extending direction is 500nm or less.

7. The cable according to any one of claims 1 to 6, wherein the high-strength aluminum-based conductor has a strand diameter of 0.35mm or less.

8. A cable according to any one of claims 1 to 7, wherein the high strength aluminium based conductor is covered with copper, nickel, silver or tin.

9. The cable according to any one of claims 1 to 6, wherein the conductor of the cable is formed by twisting the high-strength aluminum conductor and another conductor in a twisted manner.

10. The cable according to any one of claims 1 to 9, wherein the cable further has an optical fiber.

11. A cable according to any one of claims 1 to 10, wherein the cable further has a tension element.

12. The cable according to any one of claims 1 to 11, wherein the collecting unit further has a winding unit capable of winding and unwinding the cable.

13. A connection structure, comprising:

a conductor of the cable of any one of claims 1 to 12;

a terminal having a crimping portion crimped and connected to a distal end of the conductor and a connector portion connected to an opposite terminal; and

an ultraviolet curable resin covering an outer surface area including at least a portion where the cable conductor and the crimping portion are crimped and connected.

14. A connection structure, comprising:

the cable of any one of claims 1 to 12;

a terminal with a terminal barrel and an insulation barrel mounted integrally with the conductor portion and the insulation cover portion by gripping the conductor portion and the insulation cover portion exposed by removing the insulation cover from the cable with the terminal barrel and the insulation barrel, respectively; and

and a sealing material embedded part which is formed across the exposed conductor part and the insulating covering part, wherein the exposed conductor part is provided with the terminal, and the sealing material embedded part is formed by liquid silicon rubber with the elastic modulus of 0.55-0.72 MPa when the sealing material is cured at 25 ℃.

15. A wiring crimped with a crimp terminal having a crimp portion allowing a crimp connection to a conductor portion of the cable, at an end of the cable according to any one of claims 1 to 12,

in the crimp terminal, the pressure-bonding section is configured to have a cross-sectional hollow shape formed of a plate material, and the plate material is welded along a longitudinal direction in the cross-sectional hollow shape, and a seal portion is provided at one end side in the longitudinal direction of the pressure-bonding section in the cross-sectional hollow shape, the seal portion being formed by welding the plate materials in a direction intersecting the longitudinal direction in a state in which the plate materials are superposed on each other in a planar shape.

16. A wiring according to claim 15, wherein a surface area of the conductor part of the cable located opposite to the opening of the crimp part has a hydrophobic layer.

17. A mooring type mobile unit comprising the cable according to any one of claims 1 to 12, the connection structure according to claim 13 or 14, or the wiring according to claim 15 or 16.

Technical Field

The present invention relates to a cable for connecting a mooring type mobile unit to a collective unit including a power supply unit, and mooring the mooring type mobile unit to the collective unit, and power supply from the power supply unit to the mooring type mobile unit, and a connection structure, a wiring, and a mooring type mobile unit including the cable.

Background

A moving body, for example, an unmanned aerial vehicle (an unmanned aerial vehicle that moves in the air or in water by remote operation or autonomous control) has been developed for military purposes at first, but in recent years, in addition to disaster relief, an aerial unmanned aerial vehicle that photographs images from the air or performs infrared irradiation to investigate defects in infrastructure, an underwater unmanned aerial vehicle that photographs fish swimming in the sea or performs marine exploration, and the like have been developed for civil use and are used for various applications.

A conventional (aerial) unmanned aerial vehicle for domestic use is generally driven by mounting, for example, a battery (for example, a battery composed of 6 cells in which 3.7V lithium batteries are connected in series). The unmanned aerial vehicle has various specifications, and when the unmanned aerial vehicle is used for aerial photography, for example, the body weight is about 10kg, and the liftable weight is about 5 to 6 kg.

However, the operation time of an unmanned aerial vehicle using a battery mounted thereon as a drive source is short, and is at most about 20 minutes, which is limited to a short time.

Therefore, if the unmanned aerial vehicle can be operated without time limitation, it is expected that the use is further expanded, and for example, data captured from above can be continuously acquired, crime prevention measures can be applied for 24 hours, and the like.

As means for operating an unmanned aerial vehicle without time limitation, it is useful to adopt a configuration including an above-ground portion provided on the ground, a composite cable having a first end connected to the above-ground portion, and a flying object connected to a second end of the composite cable, the composite cable having two conductive wires for power supply, one or two optical fibers, and a tension element formed of one or more aramid fibers, as described in patent document 1, for example, and to moor the flying object to the above-ground portion via the composite cable and to transmit power from the above-ground portion to the flying object via the composite cable.

However, in patent document 1, as the conductive wire (conductor) constituting the composite cable, a conductive wire having a specific gravity of 8.9g/cm is used³Such big soft copper stranded conductor, consequently also must the grow as the holistic weight of composite cable, consequently, the corresponding gravity of the great weight of cable acts on the unmanned aerial vehicle in the removal all the time, and the weight that unmanned aerial vehicle can mention diminishes as a result, has the problem that can't float in the distant place. For underwater drones, it is also the heavier the cable becomes, the greater the force required for the drone to move becomes.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a cable for mooring and power supply of at least a mooring type mobile unit, which can be reduced in weight; and a connection structure, a wiring, and a mooring type mobile unit provided with the cable.

Means for solving the problems

The inventors of the present application have conducted extensive studies, and as a result, have conducted studies on optimization of a cable for mooring and power supply of an unmanned aerial vehicle floating in a remote area, and have found that: when a novel high-strength aluminum conductor having a higher tensile strength than a conventional aluminum conductor is used as a conductor of a cable instead of a soft copper conductor, the tensile strength is equal to or higher than that of the soft copper conductor, the weight of the entire cable is significantly reduced, an unmanned aerial vehicle can be floated to a distance, mooring and power supply of the unmanned aerial vehicle are possible, and fatigue resistance due to repeated release (unwinding) and winding of the cable to a cable reel accompanying takeoff and landing of the unmanned aerial vehicle is also excellent.

That is, the gist of the present invention is as follows.

(1) A cable for connecting a mooring type mobile body to a collective unit including a power supply unit, at least mooring of the mooring type mobile body to the collective unit, and power supply from the power supply unit to the mooring type mobile body, wherein at least a part of a harness constituting a conductor of the cable is a high-strength aluminum conductor.

(2) The cable according to the above (1), wherein the tensile strength of the high-strength aluminum-based conductor is 180MPa or more.

(3) The cable according to the above (1) or (2), wherein the high-strength aluminum-based conductor is formed of an 8000-based aluminum alloy.

(4) The cable according to the above (1) or (2), wherein the high-strength aluminum-based conductor is formed of a 5000-based aluminum alloy.

(5) The cable according to the above (1) or (2), wherein the high-strength aluminum-based conductor is formed of a 6000-series aluminum alloy.

(6) The cable according to any one of the above (1) to (5), wherein the high-strength aluminum-based conductor has a fibrous metal structure in which crystal grains are aligned and extended along an extending direction of the high-strength aluminum-based conductor, and an average value of a dimension of the crystal grains perpendicular to a longitudinal direction in a cross section parallel to the extending direction is 500nm or less.

(7) The cable according to any one of the above (1) to (6), wherein the high-strength aluminum-based conductor has a strand diameter of 0.35mm or less.

(8) The cable according to any one of the above (1) to (7), wherein the high-strength aluminum-based conductor is covered with copper, nickel, silver, or tin.

(9) The cable according to any one of the above (1) to (6), wherein the conductor of the cable is formed by twisting the high-strength aluminum conductor and another conductor in a twisted state.

(10) The cable according to any one of the above (1) to (9), wherein the cable further includes an optical fiber.

(11) The cable according to any one of the above (1) to (10), wherein the cable further has a tension member.

(12) The cable according to any one of the above (1) to (11), wherein the collecting unit further includes a winding unit capable of winding and unwinding the cable.

(13) A connection structure, comprising: the conductor of the cable according to any one of (1) to (12) above; a terminal having a crimping portion crimped and connected to a distal end of the conductor and a connector portion connected to the opposite terminal; and an ultraviolet curable resin covering an outer surface area including at least a portion where the cable conductor and the pressure-bonding section are pressure-bonded and connected.

(14) A connection structure, comprising: the cable according to any one of (1) to (12) above; a terminal with a wire barrel and an insulation barrel, which is integrally mounted with the conductor portion and the insulation covering portion by gripping the conductor portion and the insulation covering portion exposed by removing the insulation covering from the cable with the wire barrel and the insulation barrel, respectively; and a sealing material embedded part which is formed across the exposed conductor part and the insulating covering part, and is formed by liquid silicon rubber with the elastic modulus of 0.55-0.72 MPa when cured at 25 ℃.

(15) And an interconnection in which a crimp terminal is crimped to a terminal of the cable according to any one of the above (1) to (12), the crimp terminal including a pressure-bonding section that allows a crimp connection to be made to a conductor portion of the cable, wherein the crimp terminal includes a plate material having a cross-sectional hollow shape, the plate material is welded along a longitudinal direction in the cross-sectional hollow shape, and a seal portion is provided on one end side in the longitudinal direction of the pressure-bonding section in the cross-sectional hollow shape, the seal portion being formed by welding the plate materials in a direction intersecting the longitudinal direction in a state in which the plate materials are superposed on each other in a planar shape.

(16) The wiring according to the above (15), wherein a surface area of the conductor part of the cable located at a position opposed to the opening of the crimping part has a hydrophobic layer.

(17) A mooring type mobile unit comprising the cable according to any one of (1) to (12), the connection structure according to (13) or (14), or the wiring according to (15) or (16).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there are provided a cable having a tensile strength (tension resistance) sufficient for mooring an unmanned aerial vehicle even when the unmanned aerial vehicle is floated to a distant place (for example, a height position of 100m or more from the ground) and a cable having a length of 100m or more is suspended from the unmanned aerial vehicle, and having excellent fatigue resistance characteristics due to repeated release (unwinding) and winding of the cable to a cable reel accompanying takeoff and landing of the unmanned aerial vehicle, and a connection structure, a wiring and mooring type moving body provided with the cable, wherein at least a part of a wire harness constituting a conductor of the cable is a high-strength aluminum-based conductor, and weight of the entire cable can be reduced.

Drawings

Fig. 1 is a diagram schematically showing a moored type mobile body (aerial drone) that moors and supplies power using a cable according to the present invention and performs aerial photography using a camera in a hovering state.

Detailed Description

< Cable of the present invention >

Next, preferred embodiments of the cable according to the present invention are explained below.

Fig. 1 is a diagram schematically showing a state in which an unmanned aerial vehicle 2, which is a mooring type moving body in a hovering state, is moored and powered by using a cable 1 according to the present invention, and an aerial photograph is taken by a camera 3, which is an imaging device.

The cable 1 according to the present invention is a cable having one end connected to a collecting unit 6 which has a cable reel 4 as a winding unit and a power supply device 5 as a power supply unit and is fixedly installed on the ground, and the other end connected to the unmanned aerial vehicle 2, and is used for mooring the unmanned aerial vehicle 2 to the collecting unit 6 and supplying power from the power supply device 5 to the unmanned aerial vehicle 2.

In the cable 1 of the present invention, at least a part of the wire harness constituting the conductor of the cable 1 is required to be a high-strength aluminum conductor, and thus, the tensile strength is high, the fatigue resistance is excellent, and the weight of the entire cable can be reduced.

The cable drum 4 rotates the wind-up roller to wind up the cable 1. For example, when the unmanned aerial vehicle 2 approaches the periphery of the collecting unit 6 from a distant place, the cable 1 released (unwound) from the cable reel 4 is wound around the cable reel 4, so that the space for accommodating the cable 1 in the collecting unit 6 can be saved.

Here, as characteristics required for the cable 1 for mooring and power feeding of the unmanned aerial vehicle 2, there are: tensile strength (tension resistance) required for mooring the unmanned aerial vehicle 2, repeated bending characteristics (fatigue resistance) due to unwinding (unwinding) and winding of the cable 1 from the cable reel 4 accompanying take-off and landing of the unmanned aerial vehicle 2, high-frequency transmission for transmitting data, conductivity, and the like.

Note that, regarding the conductivity of the conductor constituting the cable 1 used in the unmanned aerial vehicle 2, if the conductor is configured to be boosted to a relatively high voltage (for example, 400V) and to transmit electric power, the current flowing through the conductor of the cable 1 can be reduced, and therefore, the conductor may have a certain degree of conductivity (for example, 35% IACS or more).

As a means for achieving weight reduction of the cable 1, for example, use of specific gravity (2.7 g/cm) has been attempted³) A small aluminum-based conductor is used as a conductor constituting the cable 1 instead of the soft copper conductor.

However, the following problems are found: since the tensile strength of a conventional aluminum conductor is at most about 160MPa even if it is high and is lower than that of a soft copper conductor (about 230 MPa), tension and bending force are repeatedly applied to the conductor constituting the cable 1 by repeating release (unwinding) of the cable 1 from the cable reel 4 and winding of the cable 1 to the cable reel 4, which are caused by take-off and landing of the unmanned aerial vehicle 2, and a part of the wire harness constituting the conductor is broken, and the resistance of the conductor tends to increase. In view of such a problem, in the cable 1 of the present invention, at least a part of the wire harness constituting the conductor of the cable 1 is a high-strength aluminum conductor.

In order to float the unmanned aerial vehicle 2 in a distance, the entire length of the cable 3 needs to be lengthened, but in the conventional soft copper stranded wire, the specific gravity is 8.9g/cm³However, in the present invention, the weight of the cable 1 having a harness of a high-strength aluminum conductor is used to provide a weight reduction effect, and thus the weight of the cable 1 acting on the unmanned aerial vehicle 2 during operation is reduced, and as a result, the weight that can be lifted by the unmanned aerial vehicle 2 is increased, and the unmanned aerial vehicle 2 can be easily floated to a far place compared to the conventional one. For underwater drones, the cable 1 also becomes lighter, and the force required for the drone to move also becomes smaller, so that the force with which the drone moves in the water can be smaller, and therefore it is advantageous.

As the camera 3 mounted on the unmanned aerial vehicle 2, for example, a recent high-performance camera has improved performance to a resolution of about 3mm when shooting at a position 100m from the ground, and therefore shooting from a higher place is possible, while the camera 3 has a large weight, and by using the lightweight cable 1, it is possible to perform operations such as mooring and power supply of the unmanned aerial vehicle 2 mounted with the camera 3, and at the same time, to float the unmanned aerial vehicle 2 to a distant place (for example, a height position 100m or more from the ground) and hover (an operating state of being stationary at one point in the air) and easily perform aerial shooting for a long time, and therefore, shooting with the camera of the unmanned aerial vehicle 2 from a higher place becomes easy, and information relating to a wider range can be obtained in a short time without moving the unmanned aerial vehicle 2 over a wide range, the use is further expanded, and is preferable from the above-mentioned point of view.

Further, since the cable 1 having the wire harness of the high-strength aluminum conductor has higher tensile strength and fatigue resistance than the conventional aluminum conductor, it is possible to suppress breakage of the wire harness caused by repetition of releasing (unwinding) and winding of the cable 1 from the cable drum 4 and increase in electric resistance of the cable 1 associated therewith.

In view of being able to reliably moor the unmanned aerial vehicle against the tension acting on the cable sufficiently when the unmanned aerial vehicle floats up, the tensile strength of the high-strength aluminum-based conductor is preferably 180MPa or more, more preferably 260MPa or more, further preferably 380MPa or more, and particularly preferably 500MPa or more.

The composition of the high-strength aluminum-based conductor is not particularly limited as long as it has a tensile strength of 180MPa or more, and may be pure aluminum or an aluminum alloy, and is particularly preferably formed of a 5000-based (Al — Mg-based), 6000-based (Al — Mg-Si-based) or 8000-based (Al-Si- (Cu, Mg-based) aluminum alloy.

Preferably, the high-strength aluminum-based conductor has a fibrous metal structure in which crystal grains are aligned and extended along an extending direction of the high-strength aluminum-based conductor, and an average value of a dimension of the crystal grains perpendicular to a longitudinal direction in a cross section parallel to the extending direction is 500nm or less. This makes it possible to increase the tensile strength of the aluminum-based conductor significantly as compared with conventional aluminum-based conductors.

The bundle diameter of the high-strength aluminum-based conductor is preferably 0.35mm or less in view of reducing deformation in the vicinity of the surface of the bent conductor.

Since the high-strength aluminum-based conductor itself sufficiently has desired characteristics, it can be used as a cable for mooring and power supply of an unmanned aerial vehicle or the like even if it is not covered. In addition, in order to impart desired characteristics, the high-strength aluminum-based conductor is preferably covered with copper, nickel, silver, or tin. When the coating is made of another metal by plating, cladding or the like, the bonding properties are good, and all of high tensile strength, fatigue resistance and electrical conductivity can be satisfied as in the case of a bare material. Further, effects such as reduction of contact resistance and improvement of corrosion resistance can be achieved. In a cross section perpendicular to the extending direction of the conductor, the coverage is preferably about 25% of the total area. This is because if the coverage is too large, the effect of weight reduction is reduced. Preferably 15% or less, more preferably 10% or less, and still more preferably 5% or less. The high-strength aluminum-based conductor may be covered with a known material used in the related art.

The conductor of the cable is preferably formed by twisting a high-strength aluminum conductor and another conductor in a twisted manner. Examples of the other conductor include copper or a copper alloy, a piano wire, a soft steel wire, a hard steel wire, and a stainless steel wire. In case a particularly high electrical conductivity is required, it is preferred to use soft copper as the further conductor.

In addition, when it is necessary to optically transmit an image of a camera mounted on the unmanned aerial vehicle, the cable preferably further includes an optical fiber.

Further, in the case where the tension resistance of the entire cable is required, the cable preferably further includes a tension member.

< connection Structure of the present invention >

From the viewpoint of preventing galvanic corrosion between the high-strength aluminum-based conductor and the terminal, it is preferable that: the cable has a connection structure provided with a terminal having a pressure-bonding section pressure-bonded to the conductor end and a connector section connected to the opposite terminal, and an ultraviolet curable resin covering an outer surface area including at least a portion where the cable conductor and the pressure-bonding section are pressure-bonded.

In addition, from the viewpoint of preventing galvanic corrosion between the high-strength aluminum-based conductor and the terminal, it is preferable that: the cable has a connection structure at (a terminal of) the cable, the connection structure including: a terminal with a wire barrel and an insulation barrel, which is integrally mounted with the conductor portion and the insulation covering portion by gripping the conductor portion and the insulation covering portion exposed by removing the insulation covering from the cable with the wire barrel and the insulation barrel, respectively; and a sealing material embedded part which is formed by spanning the exposed conductor part and the insulation covering part of the terminal and is formed by liquid silicon rubber with the elastic modulus of 0.55-0.72 MPa when cured at 25 ℃.

< Wiring of the present invention >

Further, from the viewpoint of corrosion and galvanic corrosion, it is preferable that: a cable is configured to be wired by crimping a crimp terminal at a terminal thereof, the crimp terminal including a pressure-bonding section that allows pressure-bonding connection to a conductor portion of the cable, the crimp terminal being configured such that a cross-sectional hollow shape is formed by a plate material, and the plate material is welded along a longitudinal direction in the cross-sectional hollow shape, and a seal section that is formed by welding along a direction intersecting the longitudinal direction in a state where the plate materials are superposed on each other in a planar shape is provided at one end side in the longitudinal direction of the pressure-bonding section in the cross-sectional hollow shape.

Further, from the viewpoint of preventing corrosion and galvanic corrosion, it is preferable that: the wiring has a hydrophobic layer on a surface area of a conductor part of the cable located opposite to the opening of the crimping part.

Further, the mooring type mobile unit of the present invention preferably includes: the cable having the above-described structure, and a connection structure or a wiring having the cable.

< characteristics of high-strength aluminum conductor constituting the cable of the present invention >

[ tensile Strength ]

The tensile strength was set to be in accordance with JIS Z2241: 2011 measured values. The detailed measurement conditions are described in the column of the example below.

Particularly, when the high-strength aluminum-based conductor of the present invention is a wire rod, the tensile strength is preferably 180MPa or more. The tensile strength is 60 to 170MPa (specification name: B230/B230M-07) higher than that of conductive aluminum A1350 shown in ASTM INTERNATIONAL. Therefore, for example, when the aluminum alloy wire rod material of the present invention is applied to a cable, it has an effect of reducing the cross-sectional area and weight of the conductor of the cable by 10% while maintaining the high tension of the cable. In the present invention, the tensile strength is more preferably 260MPa or more, and still more preferably 300MPa or more. More preferably, the tensile strength is 340MPa or more. The tensile strength is 305 to 330MPa (specification name: B398/B398M-14) which is higher than that of 6000 series aluminum alloy A6201 shown in ASTM INTERNATIONAL. The tensile strength is more preferably 380MPa or more, and particularly preferably 500MPa or more.

[ fatigue resistance characteristics ]

The fatigue resistance was evaluated by measuring the resistance while repeating winding and unwinding (unwinding) of the cable to a cable drum having a diameter of 20cm, and the number of repetitions when the amount of increase in resistance due to deformation reached 10% or more of the initial resistance.

[ conductivity ]

The conductivity also varies depending on the presence or absence of a pressure rise, but is preferably 35% IACS or more, and more preferably 42% IACS or more. For reference, a conductor having an electrical conductivity of 35% IACS or more and a cross-sectional area of 0.75sq is 65 Ω/km or less.

< mooring type mobile unit of the present invention >

The mooring type mobile body of the present invention is applicable to various mobile bodies that move in a moored state, that is, not only the above-described aerial drone, but also an underwater drone used for exploration or photography of the sea, river, or the like, monitoring of various cables installed in water such as submarine cables or submarine cables, and a water-air drone capable of moving from water to air.

While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention, including all embodiments included in the concept of the present invention and claims.

Examples

Next, an aerial drone as a mooring type mobile body having the cable of the present invention is trial-produced, and performance is evaluated, so that the description will be given. The following examples of the present invention are disclosed only to specifically demonstrate the effects of the present invention, and the present invention is not limited to these examples.

(examples 1 to 7 of the present invention)

The aerial drone uses a six-rotor aircraft (model number matrix 600, manufactured by DJI), which has a body weight of 8.9kg and carries six rotors (propellers). In the unmanned aerial vehicle, the rotating shaft was made of carbon, the propeller was 21 inches in diameter, a motor having a rotation speed of 130rpm/V per 1 volt was mounted, and the rotation speed of the motor was controlled by an electronic speed controller. In addition, the unmanned aerial vehicle is also equipped with 6kg of aerial camera.

As the cable used for mooring and power feeding of the aerial drone, the cables having the structures shown in table 1, the materials of the conductors and tension elements constituting the cable, the wire diameters, and the like were used, and the total length of the cable was 200 meters, and the area of the stranded conductor of the cable was 0.75 sq. Each conductor was provided with a covering made of polypropylene. A polyethylene sheath was provided on the outside thereof.

The cable is used for mooring the unmanned aerial vehicle, and supplies electric power for boosting the voltage from 100V to 400V to the unmanned aerial vehicle side by a power supply unit constituting an aggregation unit provided on the ground. The current flowing through the cable is supplied to the unmanned aerial vehicle after the voltage is reduced from 250V to 22V by a DC-DC converter mounted on the unmanned aerial vehicle.

The mass of the cable was 2.4kg for cables using high-strength aluminum alloy as a conductor (inventive examples 1 to 2, 5 to 7) and 4.4kg for cables using soft copper as a conductor (comparative example 5). The cable using high-density aluminum alloy and soft copper as the conductor was 3.0kg (inventive example 3).

[ evaluation ]

Using the unmanned aerial vehicle with the cables of the present invention examples and the comparative examples, the following characteristic evaluations were performed.

[1] Tensile strength

The tensile strength of the stranded conductor in each of the cables produced was measured in accordance with JIS Z2241: 2011 tensile strength (MPa) was measured by a tensile test using a precision universal tester (shimadzu corporation). In the present example, the tensile strength of the conductor constituting the cable was set to a satisfactory level when the tensile strength was 180MPa or more. The sheath and the cover were peeled off, and the measurement was performed in a state of only the stranded wire of the conductor. The stress was calculated by dividing the maximum value of the test force by the total cross-sectional area of the wire harness before the test.

[2] Fatigue resistance characteristics

Fatigue resistance was evaluated by measuring the number of times of repetition when takeoff and landing were repeated between a ground position and a position having a height of 200m and conductor resistance was increased by 5%. The "number of repetitions when the conductor resistance is increased by 5%" means: since the resistance of the cable (wire) changes due to the influence of tension and bending applied to the wire accompanying winding and unwinding of the cable reel and flying during each flight, the resistance is measured during each repetitive flight, and when the amount of increase in the resistance due to deformation is 10% or more higher than the initial resistance, the number of repetitions of takeoff and landing performed up to that time is determined as the number of times of flight failure. In the present embodiment, regarding the fatigue resistance, the case where the number of times of repetition of take-off and landing is 10 or more is set as the pass level.

[3] Resistance (conductivity) of stranded wire

The resistance of the strands was measured by the four-terminal method at 20. + -. 1 ℃. In this example, the resistance of a stranded wire having a cross-sectional area of 0.75sq was set to a satisfactory level when the resistance was 65 Ω/km or less.

According to the evaluation results in table 1, the tensile strength, the electrical conductivity (resistance of the twisted wire), and the fatigue resistance were all acceptable levels for the cables of examples 1 to 7 of the present invention, and the weight of the cable was reduced to about 2kg compared to comparative example 5 using a soft copper conductor.

On the other hand, in comparative examples 1 to 4, since the conventional aluminum conductor was used as the conductor constituting the cable, the weight of the entire cable was reduced and the drone was able to float up to a height of 200m, but the tensile strength of the conductor was insufficient, and the fatigue resistance was deteriorated. In comparative example 5, since the conductor constituting the cable used a soft copper conductor, the weight of the entire cable increased, and as a result, the drone could not float to a height of 200m and could only reach a position in the middle.

Description of the reference numerals

1 electric cable

2 mooring type mobile body (or unmanned plane)

3 camera device (or vidicon)

4 winding unit (or cable reel)

5 Power supply Unit

6 Unit of collections