The present invention refers to a high efficiency rope, in particular for controlling wing profiles .

A high efficiency rope for wing profile is used in particular for transmitting wind energy to a winch or hoist.

Recently, the application of winches and hoists for transmitting energy has become important in the field of wind energy management, wherein winches and hoists, connected to alternators and electronic apparatuses, are used to extract the wind kinetic energy and to convert mechanical energy into electric energy.

An important aspect in recovering mechanical energy from ropes connected to a moving load is given by the efficiency of the rope.

A process for extracting energy from wind implies the use of high-resistance ropes. The tension of the ropes is generated by the lift of a kite flying with transverse wind. The drum, onto which the rope is wound, rotates due to the unwinding force induced by the rope. The mechanical power is generated by the combination of the mechanical tension in the rope and the speed with which the rope is stretched, being unwound from the drum.

During this process, the wind kinetic energy is first of all converted into mechanical energy, due to the friction between the rope and the contact surface of the drum, then it is converted into electric energy through alternators connected to the winch.

During the conversion, energy losses occurs as heat, which heats the contact surface of the drum and increases the internal temperature of the rope impairing the mechanical properties due to the overheating .

Friction inside the rope is generated by relative displacements and deformations of different threads and strands, composing the rope and geometrically arranged in order to mutually rub themselves. On the other hand, friction between rope and drum is the necessary ingredient to allow the winch to extract energy from the rope, whicle friction depending on any relative displacement between rope and drum and between the various strands composing the rope must be reduced to a minimum.

A first problem depending on the variable load acting on a rope is given by the fact that each strand composing the rope is elastically deformed, generating a relative rubbing against the surface of contiguous strands. In this way, wear of the rope is accelerated, by raising the temperature. The interstices depending on size, amount and geometric arrangement of the strands are easily occupied by various types of pollutants, for example sand, whose shape and hardness are such as to scratch the surface of the strands, drastically reducing the rope life.

A second problem depending on the variable load acting on a rope is given by the fact that the rope is generally subjected to air-elastic phenomena of unstableness, greatly depending on a circular transverse section profile subjected to an alternate detachment of vortexes and following vibrations .

According to the prior art, ropes are used for dragging wing profiles which are made in order to reduce the air-elastic unstableness . Document WO2013085800 discloses a wind energy device for converting wind energy or for vehicle propulsion, comprising a mobile sail equipped with tie-rods to perform elliptical trajectories and connected to a drum of a winch through a cable coated with a flexible sheath having its cross section shaped as an aerodynamic profile.

According to the prior art referred to making ropes with strands for different uses, ropes are employed which are composed of strands coated with protective material in order to reduce rubbing between contiguous strands. Document WO2011144471 discloses a method for producing a metallic cable having three concentric levels coated with a rubbery substance. This metallic cable comprises: a first level or core composed of a series of strands; a second level composed of strands helically wound around the strands of the first level with a certain pitch; a third level of strands wound around the strands of the second level with an helix having a certain pitch. The method provides for a step in which the strands of the second level are assembled around the strands of the first level, followed by a step in which the strands of the first and of the second level are coated with rubber by means of an extrusion head, and a step in which the strands of the third level are assembled around the assembled strands of the first and of the second level, and then rubber- coated from inside. Rubber is preferably an elastomer .

Documents WO-Al-2009/026730, US-A-4 550 559, US-A-4 085 183 and US-A-3 911 785 disclose ropes according to the preamble of Claim 1.

Therefore, object of the present invention is solving the above prior art problems by providing a high efficiency rope, in particular for controlling wing profiles, which allows a higher energy productivity and a reduction of power losses due to friction phenomena and in favor of a reduced wear.

Another object of the present invention is providing a high efficiency rope, in particular for controlling wing profiles, composed of threads and strands and comprising at least one substance adapted to coat such threads and strands avoiding their mutual contact and compensating the related elastic deformation.

The above and other objects and advantages of the invention, as will appear from the following description, are obtained with a high efficiency rope, in particular for controlling wing profiles, as claimed in claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It is intended that all enclosed claims are an integral part of the present description.

It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) can be made to what is described, without departing from the scope of the invention, as appears from the enclosed claims.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

- Figure 1 shows a cross-sectional view of a preferred embodiment of a rope with strands lacking an external coating;

- Figure 2 shows a cross-sectional view of a first preferred embodiment of a rope according to the present invention;

- Figure 3 shows a cross-sectional view of a variation of the rope of Figure 2; and - Figure 4 shows a cross-sectional view of a further variation of the rope of Figure 2.

The terminals of a rope 1 are respectively connected to a working load (not shown) and to a storage device (not shown) according to a tension gradient which establishes a maximum value of tension at one terminal and a minimum or null value at its opposite terminal.

Advantageously, the high-efficiency rope 1, in particular for controlling at least one wing profile according to the present invention, is composed of threads and strands 11, 21, 31 and comprises at least one substance 12, 22, 32 coating and/or impregnating such threads and strands 11, 21, 31, such substance being adapted to prevent a mutual contact between such threads and strands 11, 21, 31 and to compensate a relative elastic deformation between the threads and strands 11, 21, 31 themselves.

The rope 1 according to the present invention is preferably composed of three concentric levels 10, 20, 30 (as shown, for example, in Figure 3) .

A central thread 11 having a big diameter composes a first level 10.

First strands 21 composing a second level 20 are helically wound with a certain pitch around the first level 10.

Second strands 31 composing a third level 30 are helically wound with a certain pitch around the second level 20.

The thread 11 and the strands 21, 31 are respectively coated by such substance preferably as at least one rubbery sheath 12, 22, 32 (as shown, for example, in Figure 2) .

Moreover, it is possibile to provide that at least one sheath 41 externally coats the rope 1 composed of the three levels 10, 20, 30.

The sheath 41 adheres to the bunch of strands composing the levels 10, 20, 30 (as shown, for example, in Figure 3) .

According to a variation of the rope 1 according to the present invention, the sheath 41 can assume a shape having a wing profile (as shown, for example, in Figure 4) .

The process provides for the injection through an extruder of a rubbery substance capable of filling the interstices 13, 23, 33, 43 arranged on the levels 10, 20, 30 and adhering to the internal wall of the sheath 41 (as shown, for example, in Figures 3 and 4) . The strands can be made of metallic or plastic material, for example polyethilene . Preferably, the rubbery substance and the external coating 41 are made of at least one elastomer such as, for example, silicone.

The high efficiency rope 1 allows obtaining the stated objectives, since each strand composing the rope is elastically deformed independently, allowing the substance 12, 22, 32 to be deformed without getting in contact with the contiguous strands. The interstices 13, 23, 33, 43 are occupied by the rubbery substance, which precludes pollution of atmospheric agents and of dangerous particles, such as sand grains. The external sheath 41 further protects the rope 1 from atmospheric agents .

Moreover, the shape of a wing profile assumed by the sheath 41 drastically reduces the triggering of wind-induced vibrations.

The embodiment with a rope 1 equipped with a filling of interstices and wound by an external sheath occurs according to the known art in the field of strand-type ropes.