Roll-up shade sail

Abstract

A roll-up shade sail has a frame, a cover sheet, a winding roller suitable to form a winding support to at least partially wind the cover sheet and having a roller body rotating with respect to the frame around a roller axis, and a tensioning device of the cover sheet, suitable to maintain the cover sheet in tension during winding and unfolding. The tensioning device has an elastic member exerting an elastic force on the cover sheet by a tensioning cable and housed inside a containment body housed within the roller body. The tensioning device has at least one fixed return pulley associated with the frame suitable to guide the tensioning cable in an excursion outside the roller body. The tensioning cable is connected near a second end indirectly to the elastic member through an interposition of at least one movable pulley integral with the elastic member.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and benefit of Italian Patent Application No. 102025000001485 filed Jan. 28, 2025, the contents of which are incorporated by reference in their entirety.FIELD OF THE INVENTION

[0002] The object of the present invention is a roll-up shade sail.BACKGROUND OF THE INVENTION

[0003] Roll-up shade sail installations are generally known, which are capable of providing an extendable and temporary cover suitable to protect or shelter the users of an outdoor area from atmospheric agents.

[0004] Such known-type installations generally comprise:

[0005] a roller, free to rotate about its own axis, around which at least one sail or awning is wound;

[0006] support uprights anchored to the ground or wall-mounted supports to keep the roller suspended with respect to the ground;

[0007] the c overing element, that is, the sail or awning itself, and

[0008] a system for the deployment and winding of the sail or awning around the roller.

[0009] Such a system for the deployment and winding of the sail usually provides a rope stretched between the sail and a rotating reel integral in rotation with the roller so that the roller, by rotating, pulls the reel with it. The winding of the sail and the winding of the rope follow opposite directions of rotation thanks to a return pulley system. The rotation of the roller in one direction determines, in fact, the winding of the sail and allows the unwinding of the rope; the rotation of the roller in the opposite direction determines the unwinding of the sail and the winding of the rope.

[0010] Known solutions generally comprise a pair of sails associated with the same roller and adapted to be deployed in synchrony and to extend in opposite directions. Variants with a single sail also exist.

[0011] Operationally, due to the difference in diameter between the sail being wound on the roller and the rope being wound on the reel, although subjected to the same angular speed, sail and rope are subject to translational movements of different amplitude; it therefore becomes necessary to introduce a tensioning system for the rope and thus for the sail.

[0012] Generally, such a tensioning system comprises an elastic element suitable to exert its elastic force at one of the return pulleys that support the rope associated with the reel by means of a tensioning cable.

[0013] A first technical problem present in this solution is linked to the mechanical stresses to which the elastic element is subjected and which, over time, reduce its integrity.

[0014] The known art has attempted to solve these problems by providing a sail winding roller, inside which an elastic device (mechanical spring) is concealed that works in traction, as described in EP3572597A1.

[0015] In this document, the integrity of the spring is preserved as it is intended to extend only in the direction of the axis of rotation of the roller, being guided by the walls of the roller itself.

[0016] The cable tensioning system described in EP3572597A1 provides that at the outermost end of the elastic device a cable is connected, in turn associated with a return and tensioning device.

[0017] Such return and tensioning device has the function of allowing the closing of the sail while keeping it properly tensioned thanks to at least one additional cable, associated with it, which during the closing step winds onto the reel placed at the opposite end with respect to the elastic device.

[0018] However, the solution described is not devoid of drawbacks.

[0019] In fact, during the deployment step of the sail, the elastic device (in this case a mechanical spring) is subject to a considerable extension due to the forces exerted by the traction of the cables.

[0020] Such significant extension of the elastic device consequently entails the presence of high load peaks and tensions that are not always constant and linear during the winding and deployment steps of the sail. This is due to the fact that the force exerted by an elastic spring varies along its range of excursion, as shown in FIG. 10.

[0021] The presence of high load peaks and tensions that are not always constant and linear during the winding and deployment steps of the sail negatively affects both the durability of the mechanical spring and the functionality of the shade sail.

[0022] Consequently, the elastic device, although not subjected to torsional forces and although protected from atmospheric agents, is subject to extensions that prematurely degrade the intrinsic properties of the device itself.

[0023] This problem remains unresolved in the state of the art to date.

[0024] Moreover, due to such high load peaks and tensions that are not always constant and linear, the deployment and winding systems present in the known art are not always able to ensure that the sail is properly tensioned both during the handling steps of the sail itself and in moments when the roller is stationary.

[0025] This significantly reduces the functionality of the sail. In fact, a slack sail or one subject to variable tensioning is highly prone to instability when hit by air currents and at the same time prevents adequate drainage of liquids, such as rainwater, which accumulates in pockets. In addition, a slack sail hit by air currents excessively stresses the ground-anchored uprights of the installation or the wall-mounted supports.

[0026] Therefore, the attempts of the known art, although appreciable, are not free from drawbacks and do not fully meet the present requirements.

[0027] There is therefore a need to solve the drawbacks and limitations mentioned with reference to the known art.SUMMARY OF THE INVENTION

[0028] The main purpose of the present invention is therefore to eliminate, in whole or in part, the drawbacks of the above-mentioned known art, by providing a roll-up shade sail which is equipped with a tensioning device suitable to keep the sail taut in a more constant and linear manner in every handling step and at the same time preserves the integrity of the elastic tensioning element.

[0029] Another purpose of the present invention is to provide a roll-up shade sail equipped with a tensioning device capable of more easily withstanding high loads due to the forces exerted by the cables during the handling steps of the sail.

[0030] A further purpose of the present invention is to provide a roll-up shade sail that is simple and economical to produce.

[0031] A further purpose of the present invention is to provide a roll-up shade sail equipped with a tensioning device that is simple and easy to install.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The technical features of the invention, according to the aforementioned purposes, are clearly identifiable from the content of the claims reported hereinbelow, and the advantages thereof will become more evident in the detailed description that follows, made with reference to the accompanying drawings, which represent one or more purely exemplary and non-limiting embodiments thereof, in which:

[0033] FIG. 1 shows a perspective view of a roll-up shade sail according to a first embodiment of the present invention relating to a two-flap cover sheet;

[0034] FIGS. 2, 3, and 4 show three plan views of the sail of FIG. 1, illustrated in three different winding conditions of the cover sheet;

[0035] FIGS. 2a, 3a, and 4a show an enlargement of the detail highlighted in the circle indicated with II, III, and IV respectively in FIGS. 2, 3, and 4;

[0036] FIG. 5 shows a perspective view of a roll-up shade sail according to a second embodiment of the invention relating to a single-flap cover sheet;

[0037] FIGS. 5a and 5b show an enlargement of the detail highlighted in the circle indicated with Va and Vb in FIG. 5;

[0038] FIG. 6 shows a lateral orthogonal view of a portion of a winding roller of a roll-up shade sail according to the present invention, in which a gas spring has been adopted as the elastic member;

[0039] FIG. 6a shows a sectional view of the winding roller of FIG. 6 according to a sectional plane VI-VI indicated therein;

[0040] FIGS. 6b and 6c show two enlarged portions of the winding roller of FIG. 6a;

[0041] FIG. 7 shows a plan orthogonal view of the winding roller of FIG. 6;

[0042] FIG. 7a shows a sectional view of the winding roller of FIG. 7 according to a sectional plane VII-VII indicated therein;

[0043] FIGS. 7b and 7c show two enlarged portions of the winding roller of FIG. 7a;

[0044] FIG. 8 shows a lateral orthogonal view of a portion of a winding roller of a roll-up shade sail according to the present invention, in which a mechanical traction spring has been adopted as the elastic member;

[0045] FIG. 8a shows a sectional view of the winding roller of FIG. 8 according to a sectional plane IX-IX indicated therein;

[0046] FIGS. 8b and 8c show two enlarged portions of the winding roller of FIG. 8a;

[0047] FIG. 9 shows a plan orthogonal view of the winding roller of FIG. 8;

[0048] FIG. 9a shows a sectional view of the winding roller of FIG. 9 according to a sectional plane IX-IX indicated therein;

[0049] FIGS. 9b and 9c show two enlarged portions of the winding roller of FIG. 9a;

[0050] FIG. 10 shows in a graph the load curves of an example of a mechanical spring and an example of a gas spring; and

[0051] FIGS. 11 and 12 each show a view equivalent to that of FIG. 7a in relation to two different embodiments according to the invention.DETAILED DESCRIPTION

[0052] The roll-up shade sail according to the present invention is generally denoted by 1 in the accompanying Figures.

[0053] Herein and in the following description and claims, reference will be made to the roll-up shade sail 1 in a condition of use. In this sense, any references to a lower or upper position, or to a horizontal or vertical orientation, shall be construed accordingly.

[0054] According to a general embodiment of the present invention, the roll-up shade sail 1 comprises at least one frame 2, suitable to connect the roll-up shade sail 1 to a wall or to at least one support structure 3.

[0055] The roll-up shade sail 1 comprises a cover sheet 4 which may consist of a single flap 4 (as illustrated in FIG. 5) or of two flaps 4′, 4″ (as illustrated in FIGS. 1 to 4).

[0056] The roll-up shade sail 1 comprises at least one winding roller 5, which is suitable to form a winding support to at least partially wind the cover sheet 4.

[0057] More specifically, the winding roller 5 comprises a roller body 6 directly or indirectly rotatably associated with the frame 2 so as to rotate with respect to the frame 2 around a roller axis X.

[0058] The roll-up shade sail 1 comprises at least one tensioning device 20 of the cover sheet which is suitable to maintain the cover sheet in tension during winding and unfolding, cooperating with the winding roller 5 by means of a guide cable 21 which is operatively connected to the winding roller 5 by means of a winding reel 22 integral in rotation with the roller body 6.

[0059] The single flap 4 or each of the two flaps 4′, 4″ of the cover sheet 4 is associated with the winding roller 5 at a respective fixing portion 41, 41′, 41″ and is connected to the tensioning device 20 at a respective free portion 42, 42′, 42″ opposite to the fixing portion 41, 41′, 41″.

[0060] As illustrated in FIG. 5, in the case of a single flap 4, the connection between the tensioning device and the cover sheet is made directly by means of the guide cable 21 which is directly connected to the free portion 42 of the cover sheet.

[0061] As illustrated in FIGS. 1 to 4, in the case of two flaps 4′, 4″, the connection between the tensioning device and the cover sheet is made indirectly by the guide cable 21. Indeed, the latter is kinematically connected to the two free portions 42′ and 42″ of the two flaps 4′ and 4″ by means of a balancing cable 23 which in turn connects the two free portions 42′ and 42″ to each other. The kinematic connection between the guide cable 21 and the balancing cable 23 is achieved by means of a first service pulley 210.

[0062] Operationally, as will be further described hereinbelow, the balancing cable 23 makes it possible to synchronously and evenly transmit to the two flaps the tensioning generated by the tensioning device 20.

[0063] The tensioning device 20 comprises an elastic member 31 or 32 which exerts an elastic force on the cover sheet 4 by means of a tensioning cable 24.

[0064] More specifically, in the case of a single flap, the tensioning cable 24 is connected at a first end 24′ thereof by a second service pulley 241 directly on the guide cable 21.

[0065] In the case of two flaps, the tensioning cable 24 is connected at a first end 24′ thereof—by means of a double service pulley 242—on the balancing cable 23 and, through the latter, to the guide cable 21.

[0066] As illustrated in FIGS. 6 to 9, the elastic member 31 or 32 is housed inside a containment body 33, preferably of tubular shape.

[0067] More specifically, the containment body 33 is in turn housed in a cavity formed inside the roller body 6 and extends along the roller axis X.

[0068] The elastic member 31 or 32 is arranged inside the containment body 33 so as to exert its force parallel to the roller axis X on the tensioning cable 24.

[0069] As can be seen in particular in FIGS. 6a and 8a, and the respective enlargements, the containment body 33 is integral with the frame 2 and in particular is connected thereto by means of end supports 331 and 332. One of the two end supports 331 (positioned opposite to the winding reel 22) is axially hollow to allow the passage of the tensioning cable 24.

[0070] Advantageously, the roller body 6 may be rotatably supported by the containment body 33 by means of bearings 341 and 342. In other words, the containment body 33 may act as a rotational support for the roller body 6 around the roller axis X.

[0071] As illustrated in FIGS. 7a and 9a, the tensioning device 20 comprises at least one fixed return pulley 243 which is associated with the frame 2 and in use is suitable to guide the tensioning cable in its excursion outside the roller body 6.

[0072] According to the present invention, unlike the known art, the tensioning cable 24 is not directly connected to the elastic member 31 or 32 at its own second end 24″ (opposite to the first end 24′).

[0073] According to the present invention, near the second end 24″, the tensioning cable 24 is instead connected indirectly to the elastic member 31 or 32 through the interposition of at least one movable pulley 240 integral with the elastic member parallel to the roller axis X, so as to define a mechanical system equivalent to a movable pulley.

[0074] As will be clarified hereinbelow, the introduction of a mechanical system equivalent to a movable pulley modifies the ratio between driving force (force to be applied by the winding roller) and resisting force (force applied by the elastic member), as well as the ratio between driving arm (excursion of the tensioning cable downstream of the fixed return pulley 243) and resisting arm (excursion of the elastic member) compared with the traditional case in which a direct connection is provided between the tensioning cable and the elastic member.

[0075] The ratios between forces and the ratios between arms are defined by the number of movable pulleys and the number of fixed pulleys.

[0076] In all cases, compared with a traditional shade sail, i.e., with a direct connection of the tensioning cable to the elastic element without interposition of the movable pulley, two effects are obtained:

[0077] the amplitude of the operational excursion of the elastic member is reduced, and

[0078] the force that the elastic element must exert is increased.

[0079] Both these effects are advantageous and contribute to solving the technical problem underlying the invention.

[0080] More specifically, thanks to the present invention, without altering the functionality of the roll-up shade sail, it is possible to simultaneously:

[0081] limit the operational excursion range of the elastic element by reducing the variation of the force expressed by it, thereby attenuating the intensity of the sail tensioning peaks, ensuring a more homogeneous winding and deployment of the sail itself; and

[0082] adopt a mechanically stronger elastic element; in this way, the mechanical resistance of the elastic element is increased, and thus its durability and integrity over time are improved for equal applied forces.

[0083] According to a preferred embodiment of the present invention, a single movable pulley 240 and a single fixed pulley 243 are provided.

[0084] More specifically, as illustrated in particular in FIGS. 7a-b and 9a-b, at the second end 24″ the tensioning cable 24 is fixed directly or indirectly to the frame 2.

[0085] In particular, at the second end 24″, the tensioning cable 24 is fixed to the containment body 33 and therefore indirectly to the frame 2.

[0086] As illustrated in particular in FIGS. 7b and 9b, the tensioning cable 24 is kinematically connected to the elastic member 31 or 32 by means of a movable pulley 240 which is integral with the elastic member along the roller axis X.

[0087] Operationally, the tensioning cable 24 runs over the movable pulley 240 dividing the path of the tensioning cable into two branches 24a and 24b.

[0088] Preferably, the two branches 24a and 24b are parallel to each other, and in particular to the roller axis X. In this sense, the fixing point of the second end 24″ of the tensioning cable 24 and the relative position between the fixed return pulley 243 and the movable pulley 240 are chosen so that they are aligned with each other (parallel to the roller axis X).

[0089] In turn, the movable pulley 240 follows the movements of the elastic member 31 or 32 along the roller axis X. In this way, a mechanical system equivalent to a movable pulley is defined.

[0090] A movable pulley is in fact a mechanical system in which the axis of the pulley is mobile, the rope is anchored, and the pulley itself moves.

[0091] The movable pulley is a second-class lever in which the driving arm is twice the resisting arm.

[0092] Therefore, the driving force will be half the resisting force, with Fm=Fr / 2. In general, this represents the advantage of the movable pulley. However, what is saved in force is lost in displacement. In fact, if work is equal and work is a force applied over a distance, L=F×s, wherein F is the force and s is the displacement, then Lr=Lm, wherein Lr is the work related to the resisting force and Lm to the driving force. It follows that Fr×s=Fm×s, that is, Fr×h=Fm×(2h), since the driving arm hm=2h is double the resisting arm hr=h.

[0093] Applying the above to the roll-up shade sail according to the present invention, the driving force Fm is the force applied to the tensioning cable 24 by the winding roller 5, while the driving arm hm is the translation excursion experienced by the first end 24′ of the tensioning cable 24 outside the roller body 6 with respect to the at least one fixed return pulley 243; the resisting force Fr is the force expressed by the elastic element, while the resisting arm hr is the excursion of the elastic element parallel to the roller axis X.

[0094] With the maximum translation excursion of the first end 24′ of the tensioning cable 24 with respect to the fixed pulley set and with the maximum tensioning force Ft (driving force Fm) exerted by the winding roller on the tensioning cable 24 set, the elastic member 31 or 32 is sized so as to balance the tensioning of the tensioning cable 24 with an amplitude of operational excursion of the elastic member not exceeding half of the maximum translation excursion.

[0095] In this way, compared with a traditional shade sail, i.e., with a direct connection of the tensioning cable to the elastic element without interposition of the movable pulley, two effects are obtained:

[0096] the amplitude of the operational excursion of the elastic member is halved; and

[0097] the force that the elastic element must exert is doubled.

[0098] Both these effects are advantageous and contribute to solving the technical problem underlying the present invention.

[0099] More specifically, as already highlighted, thanks to the present invention, without altering the functionality of the shade sail, it is possible to simultaneously:

[0100] limit the operational excursion range of the elastic element by reducing the variation of the force expressed by it, thereby attenuating the intensity of the sail tensioning peaks and ensuring a more homogeneous winding and deployment of the sail; and

[0101] adopt a mechanically stronger elastic element; in this way, the mechanical resistance of the elastic element is increased, and thus its durability and integrity over time are improved for equal applied forces thereon.

[0102] As already stated, thanks to the present invention, all this is achieved without altering the functionality of the shade sail. Indeed, the above-mentioned effects are obtained while keeping constant both the maximum translation excursion of the first end 24′ of the tensioning cable 24 with respect to the fixed pulley, and the maximum tensioning force Ft (driving force Fm) exerted by the winding roller on the tensioning cable 24.

[0103] The present invention is therefore based on the advantageous exploitation of the dual effect resulting from a mechanical system equivalent to a movable pulley.

[0104] The advantage deriving from the present invention can be better understood by comparing the shade sail according to the invention with a traditional shade sail, i.e., with a direct connection of the tensioning cable to the elastic element without interposition of the movable pulley.

[0105] The comparison must be made considering that the maximum translation excursion and the maximum extension force remain the same and therefore unchanged compared to the traditional case of the tensioning cable directly connected to the elastic member.

[0106] In the traditional case, Fm=Fr and hm=hr. In the case where it is desired to halve the resisting arm hr (to limit the operational excursion range of the elastic element), it is necessary to halve the driving arm hm. Likewise, in the case where it is desired to double the resisting force Fr (to adopt a mechanically stronger elastic element), it is necessary to double the driving force Fm. All this implies an alteration of the functionality of the shade sail.

[0107] In the case according to the present invention, Fr=2Fm and hr=hm / 2. Therefore, by applying the same driving force Fm and imposing the same driving arm hm as in the traditional case, it follows that the resisting force is doubled and the

[0108] resisting arm is halved.

[0109] The roll-up shade sail according to the present invention is therefore equipped with a tensioning device suitable to maintain the sail taut in a more constant and linear manner in every handling step and at the same time allows the integrity of the elastic tensioning element to be preserved.

[0110] According to further embodiments of the present invention, illustrated in FIGS. 11 and 12, more complex mechanical systems than the one described above may be provided, which allow the force ratios and arm ratios to be amplified, albeit at the cost of greater mechanical complexity.

[0111] In particular, two cases may be provided:

[0112] one movable pulley 240 and two fixed pulleys 243a and 243b, with the tensioning cable fixed at its second end 24″ to the movable pulley; in such case, the force ratios and arm ratios are defined by the number three (see FIG. 11); and

[0113] two movable pulleys 240a and 240b and two fixed pulleys 243a and 243b, with the tensioning cable fixed at its second end 24″ to a fixed pulley; in such case, the force ratios and arm ratios are defined by the number four (see FIG. 12).

[0114] More complex mechanical systems may be provided by further increasing the number of fixed and movable pulleys, accepting, however, the increase in complexity and manufacturing cost.

[0115] As illustrated in FIGS. 8, 8a-c, 9, 9a-c, the elastic member may be a mechanical traction spring 32.

[0116] Preferably, as illustrated in FIGS. 6, 6a-c, 7, 7a-c, the elastic member is a gas spring 31.

[0117] The use of a gas spring is preferable to a mechanical spring since, as shown in FIG. 10, gas springs have less pronounced load curves. For this reason, for the same excursion (or stroke), they generate a more constant force. All this, together with the reduction of the stroke of the elastic member due to the presence of a mechanical system equivalent to a movable pulley, contributes to generating a more constant and linear tension, avoiding tension peaks that make the adjustment and fine-tuning of the sail difficult.

[0118] Advantageously, the movable pulley 240 is housed inside the containment body 33.

[0119] Advantageously, the tensioning cable 24 is slidably guided from the inside of the containment body 33 to the outside by guiding means 340 so as to be parallel to the roller axis X in the section inside the containment body. In particular, as illustrated in the accompanying figures, the guiding means 340 may consist of the fixed return pulley 243 and a high-sliding ring 340′. The latter may be replaced by a second fixed pulley.

[0120] Preferably, the roll-up shade sail 1 may be motorized. In such case, the roll-up shade sail 1 comprises electric motor means, kinematically coupled to the roller body 6 and controllable to rotate the roller body around the roller axis X in both directions of rotation.

[0121] Alternatively, the roll-up shade sail 1 may be operated manually, for example by means of a winch and a crank connected to the roller body.

[0122] The present invention allows to achieve numerous advantages, partly already described.

[0123] The roll-up shade sail 1 according to the present invention is equipped with a tensioning device that is suitable to maintain the sail taut in a more constant and linear manner in every handling step, limiting tension peaks and allowing better preservation of the integrity of the elastic tensioning member.

[0124] The roll-up shade sail 1 according to the present invention is equipped with a tensioning device that can more easily withstand high loads due to the forces exerted by the cables during the handling phases of the sail.

[0125] The roll-up shade sail 1 according to the present invention is simple and economical to manufacture.

[0126] The roll-up shade sail 1 according to the present invention is simple and easy to install.

[0127] The invention thus conceived therefore achieves the intended purposes.

[0128] Obviously, in its practical implementation it may also assume forms and configurations different from those illustrated above, without thereby departing from the present scope of protection.

[0129] Moreover, all the details may be replaced by technically equivalent elements, and dimensions, shapes and materials used may be of any kind depending on the requirements.

Claims

1. A roll-up shade sail comprising:at least one frame suitable to connect the roll-up shade sail to a wall or to at least one support structure;a cover sheet consisting of a single flap or of two flaps;at least one winder roller, which is suitable to form a winding support to at least partially wind the cover sheet and comprises a roller body directly or indirectly rotatably associated with the frame so as to rotate with respect to the frame around a roller axis;at least one tensioning device of the cover sheet which is suitable to maintain the cover sheet in tension during winding and unfolding, cooperating with the winder roller by a guide cable operatively connected to the winder roller by a winding reel integral in rotation with the roller body,wherein the single flap or each of the two flaps of the cover sheet is associated with the winder roller at a fixing portion thereof and is connected to the tensioning device at a free portion thereof opposite to the fixing portion, in the case of the single flap, the guide cable being directly connected to the free portion, and in the case of the two flaps the guide cable being kinematically connected to the two free portions of the two flaps by a balancing cable connecting the two free portions to each other,wherein the tensioning device comprises an elastic member that exerts an elastic force on the cover sheet by a tensioning cable which, in the case of the single flap, is connected at a first end thereof by a pulley directly on the guide cable, while in the case of the two flaps, the tensioning cable is connected at a first end thereof by a pulley directly on the balancing cable,wherein the elastic member is housed inside a containment body which in turn is housed in a cavity formed inside the roller body and extends along the roller axis, the elastic member being arranged so as to exert the elastic force parallel to the roller axis on the tensioning cable, the containment body being integral with the frame,wherein the tensioning device further comprises at least one fixed return pulley which is associated with the frame and in use is suitable to guide the tensioning cable in an excursion outside the roller body, andwherein the tensioning cable is connected near a second end indirectly to the elastic member by an interposition of at least one movable pulley integral with the elastic member parallel to the roller axis, so as to define a mechanical system equivalent to a movable pulley.

2. The roll-up shade sail of claim 1, wherein the tensioning cable is fixed at the second end directly or indirectly to the frame and is kinematically connected to the elastic member by a single movable pulley integral with the elastic member along the roller axis, so as to define a mechanical system equivalent to a movable pulley, and wherein, having set a maximum translation excursion of the first end of the tensioning cable with respect to the at least one fixed return pulley and having set a maximum tensioning force exerted by the winder roller on the tensioning cable, the elastic member is sized so as to balance a tensioning of the tensioning cable with an operating excursion amplitude of the elastic member equal to half of the maximum translation excursion.

3. The roll-up shade sail of claim 1, wherein the elastic member is a gas spring.

4. The roll-up shade sail of claim 1, wherein the elastic member is a mechanical traction spring.

5. The roll-up shade sail of claim 1, wherein the at least one movable pulley is housed inside the containment body.

6. The roll-up shade sail of claim 1, wherein the tensioning cable is slidably guided inside the containment body by guiding means so as to be parallel to the roller axis.

7. The roll-up shade sail of claim 1, wherein the containment body acts as a rotational support for the roller body around the roller axis.

8. The roll-up shade sail of claim 1, further comprising motor means kinematically coupled to the roller body and controllable to rotate the roller body around the roller axis in both directions of rotation.

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