COMPACT DEVICE FOR COVERING A SURFACE COMPRISING TWO AXLES FOR DEPLOYING AND REMOVING THE COVER

Abstract

A device for covering a is provided that includes (a) a cover, each longitudinal edge of which is provided with a protruding element; (b) a drum mounted so as to rotate on frames and capable of winding the cover; (c) a translation system for translatably moving the drum on rails that are placed on either side of the surface; (d) a system for continuously locking/unlocking the protruding element into/from the rails during the translation of the drum. The translation system includes: a first rotation means (M1) for activating the rotation of a closing axle that winds a pull cord (21) enabling the drum to be pulled in an opening direction (Do) along the rails. The drum (2) is translatably mounted so as to also be moved in translation along a component perpendicular to the plane (X, Y) so that the drum always rests on the surface or on the rails.

Claims

1. A device (1) for covering a surface (3) contained within a rectangle having first and second lengths extending parallel to a longitudinal axis (X) and first and second widths extending parallel to a transverse axis (Y) normal to the longitudinal axis (X) and defining with the latter a plane (X, Y), the device comprising: a substantially rectangular cover (10) with dimensions equal to those of the rectangle and having first and second longitudinal edges opposite one another and first and second transverse edges opposite one another, the second transverse edge (10f) being fixed at the second width of the rectangle in which the surface (3) is inscribed and each longitudinal edge being provided with a projecting element (12) extending along the corresponding longitudinal edge defining a profile in section normal to the corresponding longitudinal edge having a minimum diameter (d); two rails (6) placed on respective opposite sides of said surface (3) parallel to the longitudinal axis (X), each rail consisting of a profiled member having an opening (14) on one of its faces and oriented away from the surface to be covered, the opening giving access to a space (14e) in the rail defining with the opening a groove extending all along each rail; a drum (2) formed of an axle (2e) and at least a portion of the cover (10) that is at least partially rolled around the axle and the first transverse edge of which is fixed to the axle in which: the drum (2) extends above the surface parallel to the transverse axis (Y), the axle (2e) is mounted at each of first and second ends on first and second chassis (23), on the one hand, rotationally enabling rolling and unrolling of the cover (10) and, on the other hand, enabling movement in translation of the drum parallel to the longitudinal axis (X) along the two rails (6), on the one hand, in a closing direction (Dc) and, on the other hand, in an opening direction (Do); the axle (2e) is provided with a second rotation means (M2) enabling the drum to be turned in one direction to roll the cover (10) up on the drum and at the same time to drive the movement in longitudinal translation of the drum in the opening direction (Do) leading to the removal of the cover from the surface (3); an insertion system adjacent to the drum (2) on each of the first and second chassis (23) on each side of the surface to be covered and making it possible to guide, to position and to insert the projecting element (12) of each longitudinal edge of the cover in the space (14e) through the opening (14) of the corresponding rail (6) during the movement in translation of the drum in the closing direction (Dc), the insertion system including a cover insertion pulley (32); in which the projecting element (12) at each longitudinal edge and the groove of the corresponding rails are configured so that once inserted in the space (14e) by the insertion system the projecting element occupying on its own the space (14e): is not able to leave it only by the action of a force (F) applied parallel to the transverse axis (Y) in the direction of the surface to be covered, and can leave it during rolling up of the cover (10) onto the drum (2) moving in the opening direction (Do) leading to removal of the cover; wherein the drum (2) is mounted to be mobile in translation also enabling movement in translation along a component perpendicular to the plane (X, Y) in order for the drum to remain at all times: either on a cover portion between the second transverse edge (10f) and the cover insertion pulley (32) of the insertion system provided downstream relative to a closing direction (Dc) of the drum (2) for any value of a radius (R) of the drum that depends on the length of the cover rolled up on the axle (2e) of the drum, or on the rails or on the surfaces adjacent to the rails between each rail and the surface, downstream relative to the closing direction (Dc) of the cover insertion pulley (32) of the insertion system; and wherein the device further comprises: first and second pull cords (21) each having a mobile end (21m) coupled so as to move with a first and second chassis (23) and a fixed end (21f) coupled to first and second corners of the surface, respectively, so as to remain substantially immobile in the direction of the longitudinal axis (X), the first and second corners being defined by the intersection between the first width of the surface and the first and second lengths, respectively; and a closing axle (1) extending parallel to the transverse axis (Y) and having first and second ends each fixed in rotation enabling rolling and unrolling of the first and second pull cords (21), the closing axle (1) being provided with a first axle rotation means (M1) enabling the closing axle to turn in one direction to roll the first and second pull cords (21) onto the closing axle (1) and at the same time to drive the movement in longitudinal translation of the chassis (23) and of the drum (2) along the two rails in the closing direction (Dc), driving rotation of the drum (2) and deployment of the cover over the surface (3).

2. The device as claimed in claim 1 wherein the fixed end (21f) of each pull cord (21) is coupled to the first or second corner of the corresponding surface; the mobile end (21m) of each pull cord (21) is coupled to the closing axle (1); and the closing axle (1) is coupled to the first and second chassis (23) downstream of the drum (2).

3. The device as claimed in claim 1 wherein the fixed end (21f) of each pull cord (21) is coupled to the first or second corner of the corresponding surface; the mobile end (21m) of each pull cord (23) is coupled to the closing axle (1); and the closing axle (1) is coupled to the first and second chassis (23) and is positioned inside and coaxially with the axle (2e) of the drum (2).

4. The device as claimed in claim 1 wherein the closing axle (1) is positioned at the level of the first width of the surface; the fixed end (21f) of each pull cord (21) is coupled to the closing axle (1) at the corresponding first or second corner of the surface; and the mobile end (21m) of each pull cord (21) is fixed to the corresponding chassis (23).

5. The device as claimed in claim 1 further comprising first and second idler pulleys (31) on the first and second chassis (23) on each side of the surface to be covered making it possible to guide, to position and to insert the corresponding pull cord (21) in the space (14e) through the opening (14) of the corresponding rail (6) during the movement in translation of the drum in the opening direction (Do).

6. The device as claimed in claim 1 wherein the drum (2) is mounted on each of the first and second chassis (23) by either a lever arm (2L) having a first end coupled to a respective chassis and a second end coupled in rotation to the drum, the lever arms being configured to pivot relative to the respective chassis about an axis parallel to the transverse axis (Y); or a guide (2r) extending along at least one component normal to the plane (X, Y); and wherein the rotation of the lever arm (2L) or the guide (2r) enabling the first and second ends of the drum to rest at all times on the rails or on the surfaces adjacent to the rails between each rail and the surface, including during movements of the drum (2) in the opening direction (Do) and the closing direction (Dc).

7. The device as claimed in claim 1 wherein the first rotation means (M1) and the second rotation means (M2) comprise a motor or a crank.

8. The device as claimed in claim 1 wherein in a section normal to each longitudinal edge of the cover the corresponding projecting element (12) defines a generally convex geometry; in a cross section normal to the longitudinal axis (X) the opening (14) of the groove has a maximum width (Lo) and the space (14e) has a maximum width (Le) greater than the maximum width (Lo) of the opening (14) (Lo<Le), where the maximum widths (Lo, Le) are measured parallel to the transverse axis (Y); and the projecting element (12) of each longitudinal edge and the groove of the corresponding rail are configured so that once inserted in the space (14e) by the cover insertion pulley (32) the projecting element occupying on its own the space (14e) is not able to leave it by only the action of a force (F) applied parallel to the transverse axis (Y) in the direction of the surface to be covered.

9. The device as claimed in claim 8 wherein the minimum diameter (d) of the projecting element is less than the maximum width (Lo) of the opening (14) (d<Lo); the projecting element has a maximum diameter (D) greater than the maximum diameter (Lo) of the opening (14) (Lo<D); and the cover insertion pulley (32) is configured to orient the projecting element (12) through the opening (14) of the corresponding rail by having a diameter between d and D inclusive and less than Lo, the projecting element changing orientation once the projecting element is located in the space (14e).

10. The device as claimed in claim 8 wherein the projecting element of each longitudinal edge is compressible so that in a rest configuration the minimum diameter (d) is equal to do which is between the maximum widths (Lo, Le) of the opening (14) and of the space (14e) of the corresponding rail, inclusive (Lo<d0<Le); and in a compressed configuration the minimum diameter is equal to d1 which is less than or equal to the maximum width (Lo) of the opening (14) of the corresponding rail (d1?Lo); and wherein the cover insertion pulley (32) enables compression of the projecting element (12) into its compressed configuration during its insertion through the opening (14) of the corresponding rail (6), the projecting element (12) recovering its alignment configuration once the projecting element is located in the space (14e).

11. The device as claimed in claim 8 wherein the projecting element (12) of each longitudinal edge is a cable in the form of consecutive turns forming a coil spring the axis of which is parallel to the corresponding longitudinal edge of the cover (10), in which the turns are defined so that in a rest configuration the minimum diameter (d) measured parallel to the transverse axis (Y) of each turn at rest is equal to do which is between the maximum widths (Lo, Le) of the opening (14) and of the space (14e) of the corresponding rail, inclusive (Lo<d0<Le); and in a deformed configuration the angle between the deformed turns and the longitudinal axis (X) is modified so that the minimum diameter (d) measured in a plane normal to the longitudinal axis (X) of each deformed turn is equal to d1 which is less than or equal to the maximum width (Lo) of the opening (14) of the corresponding rail (d1?Lo); and wherein the insertion system enables local deformation of the turns into their deformed configuration during their insertion through the opening (14) of the corresponding rail (6), the turns recovering their rest configuration once they are located in the space (14e).

12. The device as claimed in claim 1 wherein the projecting element (12) of each longitudinal edge includes a plurality of hooks placed side by side and having an L or j profile having a portion continuously aligned with the surface of the cover and fixed to the corresponding longitudinal edge of the cover; and a transverse portion forming a hook extending transversely relative to the aligned portion; and wherein each rail includes a flange (6a) partially closing the side of the opening (14) of each rail (6) adjacent to the surface to be covered and adapted to receive the transverse portion of the hooks.

13. The device as claimed in claim 1 further comprising a first and second anti-lifting guides (25), wherein the first and second anti-lifting guides (25) have an external portion coupled to the corresponding first and second chassis and an internal portion coupled to the corresponding rail so as to be able to slide freely along the rails parallel to the longitudinal axis (X) and unable to be extracted from the rails (14) by the application of a force perpendicular to the longitudinal axis (X).

14. The use of a device as claimed in claim 1 wherein the surface (3) is selected from: a pool filled or not with a liquid, or a sports ground, or a vehicle body, or a glazed surface, an opening in a wall.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0076] The above aspects and other aspects of the invention will become clearer in the detailed description of particular embodiments of the invention, reference being made to the drawings, in which:

[0077] FIG. 1 is a general view of a device for covering a surface formed by a swimming pool.

[0078] FIG. 2(a) is a view of a first variant system for movement in translation of the drum in closed position.

[0079] FIG. 2(b) is a view of the first variant of the system for movement in translation of the drum from FIG. 2(a) in open position.

[0080] FIG. 2(c) is a view of a second variant of the system for movement in translation of the drum in closed position.

[0081] FIG. 2(d) is a view of the second variant of the system for movement in translation of the drum from FIG. 2(c) in open position.

[0082] FIG. 3(a) is a view of a third variant of the system for movement in translation of the drum in closed position.

[0083] FIG. 3(b) is a view of the third variant of the system for movement in translation of the drum from, FIG. 3(a) in open position.

[0084] FIG. 3(c) is a view of a fourth variant of the system for movement in translation of the drum in closed position.

[0085] FIG. 3(d) is a view of the fourth variant of the system for movement in translation of the drum from FIG. 3(c) in open position.

[0086] FIG. 4(a) is a view of a variant of the system for movement in translation of the covering device.

[0087] FIG. 4(b) is a view of an alternative variant of the system for movement in translation of the covering device.

[0088] FIG. 4(c) is a view of another alternative variant of the system for movement in translation of the covering device.

[0089] FIG. 4(d) is a view of another alternative variant of the system for movement in translation of the covering device.

[0090] FIG. 5(a) is a view of a variant of the covering device in open position.

[0091] FIG. 5(b) is a view of the variant from FIG. 5(a) of the covering device with the drum in movement in translation in the closing direction, deploying the cover over the surface.

[0092] FIG. 5(c) is a view of the variant from FIG. 5(a) of the covering device in closed position.

[0093] FIG. 5(d) is a view of the variant from FIG. 5(a) of the covering device with the drum in movement in translation in the opening direction, removing the cover from the surface.

[0094] FIG. 6(a) is a view of a variant of the covering device in open position.

[0095] FIG. 6(b) is a view of the variant from FIG. 6(a) of the covering device with the drum in movement in translation in the closing direction, deploying the cover over the surface.

[0096] FIG. 6(c) is a view of the variant from FIG. 6(a) of the covering device in closed position.

[0097] FIG. 6(d) is a view of the variant from FIG. 6(a) of the covering device with the drum in movement in translation in the opening direction, removing the cover from the surface.

[0098] FIG. 7(a) is a view of a variant of the covering device in open position.

[0099] FIG. 7(b) is a view of the variant from FIG. 7(a) of the covering device with the drum in movement in translation in the closing direction, deploying the cover over the surface.

[0100] FIG. 7(c) is a view of the variant from FIG. 7(a) of the covering device in closed position.

[0101] FIG. 7(d) is a view of the variant from FIG. 7(a) of the covering device with the drum in movement in translation in the opening direction, removing the cover from the surface.

[0102] FIG. 8(a) is a view in section of a variant of the projecting element outside the rail.

[0103] FIG. 8(b) is a view in section of the variant from FIG. 8(a) of the projecting element introduced into the opening of the rail.

[0104] FIG. 8(c) is a view in section of the variant from FIG. 8(a) of the projecting element locked into the opening of the rail.

[0105] FIG. 8(d) is a perspective view of the variant from FIG. 8(a) of the projecting element locked in the opening of the rail.

[0106] FIG. 9(a) is a view in section of another variant projecting element outside the rail.

[0107] FIG. 9(b) is a view in section of the variant from FIG. 9(a) of the projecting element when it is introduced into the opening of the rail.

[0108] FIG. 9(c) is a view in section of the variant from FIG. 9(a) of the projecting element locked into the opening of the rail.

[0109] FIG. 10(a) is a view in section of another variant projecting element outside the rail.

[0110] FIG. 10(b) is a view in section of the variant from FIG. 10(a) of the projecting element when it is introduced into the opening of the rail.

[0111] FIG. 10(c) is a view in section of the variant from FIG. 10(a) of the projecting element locked into the opening of the rail.

[0112] FIG. 10(d) is a view from above of the variant from FIG. 10(a) of the projecting element locked into the opening of the rail.

[0113] FIG. 10(e) is a lateral view of the variant from FIG. 10(a) of the projecting element locked into the opening of the rail.

[0114] FIG. 11(a) is a view in section of another variant projecting element outside the rail.

[0115] FIG. 11(b) is a view in section of the variant from FIG. 11(a) of the projecting element locked into the opening of the rail.

[0116] FIG. 11(c) is a view in perspective of the variant from FIG. 11(a) of the projecting element locked into the opening of the rail.

[0117] FIG. 12 is a view in section of an anti-lifting element mounted on the rail.

[0118] FIG. 13 is a lateral view of a variant system for insertion of the projecting element.

[0119] FIG. 14 is a perspective view of the drum with an insertion and guide system in the form of an elongate opening in the chassis.

[0120] FIG. 15(a) is a view of a first variant system for insertion of the projecting element and movement in translation of the drum in closed position (i.e. the cover is not rolled much if at all onto the axle of the drum) with a guide in the form of an elongate opening extending perpendicularly to the plane (X, Y).

[0121] FIG. 15(b) is a view of the first variant from FIG. 15(a) in open position (i.e. the cover is rolled up on the axle of the drum).

[0122] FIG. 15(c) is a view of a second variant of the system for insertion of the projecting element and movement in translation of the drum in closed position (i.e. the cover is rolled up on the axle of the drum), with a guide in the form of a curvilinear opening.

[0123] FIG. 15(d) is a view of the second variant from FIG. 15(c) in open position (i.e. the cover is rolled up on the axle of the drum).

DETAILED DESCRIPTION OF THE INVENTION

[0124] As represented in FIG. 1 the (automatic) device (1) according to the invention for covering a surface (3) includes a cover (10) intended to protect said surface (3). The surface (3) is contained within a rectangle having first and second lengths extending parallel to a longitudinal axis (X) and first and second widths extending parallel to a transverse axis (Y) normal to the longitudinal axis (X) and defining with the latter a plane (X, Y). The device (1) is in particular for covering surfaces defined by the contour of a pool of water such as a swimming pool, water treatment basin, wastewater treatment station, retaining pool, desalination station, etc. However, the invention could be employed in any field necessitating the covering of a surface, for example a sports ground, such a clay or grass tennis court, a vehicle body, a glazed surface, for example of a greenhouse, a window of a vehicle such as a train or a bus, or a winter garden, or an opening in a wall, etc. Generally speaking, in the present application there is meant by surface any zone delimited by a substantially rectangular perimeter.

[0125] The device (1) includes a substantially rectangular cover (10) with dimensions equal to those of the rectangle and having first and second longitudinal edges opposite one another and first and second transverse edges (10m, 10f) opposite one another. As depicted in FIGS. 8 to 11 and 14 each longitudinal edge is provided with a projecting element (12) extending along the corresponding longitudinal edge defining a profile in section normal to the corresponding longitudinal edge having a minimum diameter (d).

[0126] The second transverse edge (10f) of the cover is fixed to the second width of the surface (3). Any known type of fixing system conforming to the criteria of stress, of safety and, where applicable, of seal, depending on the application, may be used to fix the second transverse edge (10f) at the second width of the surface. For example, the fixing system may include a plurality of belts secured to the second transverse edge of the cover (10) said belts being for example provided with anchor hooks that are fixed along the second width of the surface (3) to be covered. Alternatively, the second transverse edge of the cover may be provided with eyelets that come to be fixed at the second width of the surface by means of a series of pitons, screws, a cable or cord, or any other means. Another variant wedges the second transverse edge of the cover under a plate having a length corresponding to the width of the cover, fixed to the surface by screws passing through the cover. These anchor means and others too numerous to mention immobilize the second transverse edge (10f) of the cover (10).

[0127] The device includes two rails (6) placed on respective opposite sides of said surface (3) parallel to the longitudinal axis (X). Each rail consists of a profiled member having an opening (14) on one of its faces oriented away from the surface to be covered. The opening gives access to a space (14e) in the rail defining with the opening a groove extending all along each rail, some examples of which are depicted in FIGS. 8 to 12.

[0128] A drum (2) is formed of an axle (2e) and at least a portion of the cover (10) the first transverse edge (10m) of which is fixed to the axle (2e) and that is at least partially rolled up around the axle. The drum (2) extends above the surface parallel to the transverse axis (Y). As depicted in FIGS. 4 to 7 the axle (2e) is mounted at each of first and second ends on first and second chassis (23), on the one hand [0129] mobile in rotation for rolling and unrolling the cover (10) in order to withdraw the cover and to deploy it over the surface, respectively, and, on the other hand [0130] mobile in translation for moving the drum in translation parallel to the longitudinal axis (X) along the two rails (6), on the one hand, in a closing direction (Dc) to deploy the cover over the surface and, on the other hand, in an opening direction (Do) to remove the cover from the surface.

[0131] An insertion system includes a pulley (32) for inserting the cover adjacent to the drum (2) on each of the first and second chassis (23) on each side of the surface to be covered. The insertion system is for guiding, positioning and inserting the projecting element (12) on each longitudinal edge of the cover into the space (14e) via the opening (14) in the corresponding rail (6) during movement in translation in the closing direction (Dc) of the drum and to disengage it during movement in translation in the opening direction (Do). As depicted in FIGS. 8 to 11 the projecting element (12) of each longitudinal edge and the groove of the corresponding rails are configured so that once inserted in the space (14e) by the insertion system the projecting element occupying on its own the space (14e) [0132] cannot exit from it by only the action of a force (F) applied parallel to the transverse axis (Y) in the direction of the surface to be covered (cf. FIG. 1), and [0133] can exit from it when rolling up the cover (10) on the drum (2) moving in the opening direction (Do) leading to removal of the cover.

[0134] The essential feature of the present invention is the system for movement in translation of the drum in the closing and opening directions (Dc, Do) that is compatible with the system for inserting/removing the projecting element (12) of the cover in/from the opening and the space of the rail (14, 14e). The system in accordance with the present invention for moving the drum in translation combines rotation of the axle (2e) of the drum and rotation of a second axlethe closing axle (1)as well as a freedom of movement of the drum (2) in the direction perpendicular to the plane (X, Y).

[0135] In order to activate the movement in translation of the drum in the opening direction (Do) the axle (2e) is provided with a second drum rotation means (M2) for turning the drum in a direction to roll the cover (10) onto the drum. As the second longitudinal edge (10f) is fixed at the second width of the surface the rotation of the drum in the right direction creates traction parallel to the longitudinal axis (X) on the cover which pulls the drum, thereby driving the movement in longitudinal translation of the drum in the opening direction (Do) enabling withdrawal of the cover from the surface (3). The second drum rotation means (M2) may include a motor or a crank. The motor (M2) is preferably an electric motor and is advantageously powered by batteries connected to photovoltaic cells. The axle (2e) of the drum may turn freely in the other rotation direction, i.e. in the direction of unrolling the cover when the drum moves in the closing direction (Dc).

[0136] In order to activate the movement in translation of the drum in the closing direction (Dc) the device includes first and second traction pull cords (21), each having a mobile end (21m) coupled so as to be moved with the first and second chassis (23) and a fixed end (21f) coupled to first and second corners of the surface, respectively, so as to remain substantially immobile in the direction of the longitudinal axis (X). The first and second corners are defined by the intersection between the first width of the surface and the first and second lengths, respectively.

[0137] A closing axle (1) extending parallel to the transverse axis (Y) and having first and second ends each fixed in rotation enables rolling and unrolling of the first and second pull cords (21). The closing axle (1) is provided with a first means (M1) for rotating the closing axle (1) enabling the axle to be turned in a direction to roll up the first and second pull cords (21) on the opening axle (1) and at the same time driving longitudinal movement in translation of the chassis (23) and the drum (2) along the two rails in the closing direction (Dc). As the second longitudinal edge (10f) is fixed at the second width of the surface the movement in translation of the drum in the closing direction (Dc) moves the drum away from the second width and creates tension in the cover parallel to the longitudinal axis (X) that causes free rotation of the drum (2) and deployment of the cover over the surface (3) when the drum is moved. The closing axle (1) can turn freely in the other rotation direction, i.e. in the direction unrolling the pull cords (21) when the drum is moved in the opening direction (Do).

[0138] The drum (2) is mounted to be mobile in translation allowing movement in translation also along a component perpendicular to the plane (X, Y) in order for the drum to remain permanently [0139] either over a cover portion between the second transverse edge (10f) and the cover insertion pulley (32) of the insertion system provided downstream of the drum (2) for any value of a radius (R) of the drum that depends on the length of cover rolled up on the axle (2e) of the drum, [0140] or on the rails or the surfaces adjacent to the rails between each rail and the surface, downstream of the cover insertion pulley (32) of the insertion system.

[0141] The term downstream is defined relative to the closing direction (Dc).

Closing Axle (1) and Pull Cords (21)

[0142] In a first variant depicted in FIGS. 4(a), 4(d), 5(a) to 5(d), and 7(a) to 7(d) the fixed end (21f) of each pull cord (21) is coupled to the first and second corners of the corresponding surface. The mobile end (21m) of each pull cord (21) is coupled to the closing axle (1) and the closing axle (1) is coupled to the first and second chassis (23) downstream of the drum (2). Rotation of the closing axle (1) in the correct direction rolls up the pull cords (21), applying tension thereto in a direction parallel to the longitudinal axis (X) activating the movement in translation of the drum in the closing direction (Dc).

[0143] In a second variant depicted in FIG. 4(c) the fixed end (21f) of each pull cord (21) is coupled to the first or second corners of the corresponding surface. As in the first variant the mobile end (21m) of each pull cord (21) is coupled to the closing axle (1). The closing axle (1) is also coupled to the first and second chassis (23), not downstream of the drum but positioned inside and coaxially with the axle (2e) of the drum (2). This variant enables the size of the structure formed by the chassis (23) and the drum and closing axles (1, 2e) to be reduced.

[0144] In a third variant depicted in FIGS. 4(b) and 6(a) to 6(d) the closing axle (1) is not coupled to the chassis (23) but positioned at the level of the first width of the surface. For aesthetic reasons and to minimize the overall size, as depicted in the preceding figures, it is preferable for the closing axle (1) to be positioned in a trench below the level of the plane (X, Y) at the level of the cover. The fixed end (21f) of each pull cord (21) is coupled to the closing axle (1) at the corresponding first and second corners of the surface. Whereas in the above first and second variants the fixed ends (21f) each fixed to a corner of the surface were perfectly immobile, in the present variant they are merely substantially immobile in the direction of the longitudinal axis (X) because they are able to oscillate with an amplitude equal to the radius of the closing axle (1) when the latter rotates. The amplitude of oscillation is however negligible relative to the length of the surface (3) and it is therefore possible to consider that the fixed ends (21f) remain substantially immobile in the direction of the longitudinal axis (X) relative to the distance traveled by the mobile ends (21m) that precede the drum (2) along the length of the surface (3) in the closing direction (Dc). The mobile end (21m) of each pull cord (21) is fixed to the corresponding chassis (23). As in the previous variants the rotation of the closing axle applies tension to the pull cords (21) that pull the drum in the closing direction (Dc). Like the second variant, this variant is very compact and moreover provides easy handling access to the closing axle.

[0145] In all cases, when the drum is moved in the opening direction (Do) activated by the rotation of the drum by the second rotation means (M2) the pull cords (21) are spontaneously unrolled from the closing axle (1), which turns freely in this direction. It is preferred that, during movement of the drum in the opening direction (Do), the pull cords (21) are inserted in the opening (14) of the rails (6) over the length separating the first transverse edge from the surface of the drum as they are unrolled from the closing axle (1). If the pull cords (21) are dimensioned correctly, obstructing the opening (14), this makes it possible to prevent foreign bodies such as gravel, dust, dead leaves, mud, etc. entering via the opening and filling the space (14e). To make it possible to guide, to position and to insert the corresponding pull cord (21) in the space (14e) via the opening (14) in the corresponding rail (6) during movement in translation of the drum in the opening direction (Do) the device may be equipped with first and second idler pulleys (31) on the first and second chassis (23) on each side of the surface to be covered, as depicted in FIGS. 2 to 4.

[0146] As the projecting element of the cover (10) is inserted in the space (14e) between the drum (2) and the second width of the surface the opening is obstructed at all times and protected over practically all of the length of the rails, with the exception of the portion of the rails close to or at the level of the drum. This facilitates maintenance of the device enormously.

[0147] The first axle rotation means (M1) may include a motor or a crank. The motor is preferably an electric motor and is advantageously powered by batteries connected to photovoltaic cells.

Freedom of Movement of the Drum Perpendicular to the Plane (X, Y)

[0148] The drum (2) is coupled to the first and second chassis (23) also enabling movement in translation along a component perpendicular to the plane (X, Y). In this way the drum rests at all times on the rails or on the surfaces adjacent to the rails between each rail and the surface, including during movements of the drum (2) in the opening direction (Do) and the closing direction (Dc). If the axle (2e) of the drum is surrounded by a cover portion the drum rests on that cover portion. If on the other hand the cover is completely unrolled from the axle, which may be the case when the surface is completely covered, then it is the axle (2e) of the drum that rests on the rails or the adjacent surface. Depending on whether the insertion pulley (32) is upstream or downstream of the drum (in the closing direction (Dc)) the drum rests directly on the rails and/or at least a portion of the surface between the rails, where it rests on a cover portion already locked and covering a portion of the surface between the rails directly downstream of the drum, respectively (compare e.g. FIGS. 2(a) and 2(b) with FIGS. 2(c) and 2(d)).

[0149] In a first variant depicted in FIGS. 1, 2(a) to 2(d), 4(a) to 4(d) and 13, the freedom of movement of the drum perpendicular to the plane (X, Y) is made possible by a lever arm (2L) having a first end coupled to a respective chassis and a second end rotationally coupled to the drum, the lever arms being configured to pivot relative to the respective chassis about an axis parallel to the transverse axis (Y). The drum can therefore be moved over a plane normal to the plane (X, Y) and parallel to the longitudinal axis (X) over a circular arc trajectory. If the plane (X, Y) is substantially horizontal the drum rests spontaneously on the rails through gravity. If the plane (X, Y) has a large vertical component the lever arm (2L) may be provided with a spring that pushes the arm against the rails.

[0150] In a second variant depicted in FIGS. 3(a) to 3(d), 14 and 15(a) to 15(d), the freedom of movement of the drum perpendicular to the plane (X, Y) is made possible by a guide (2r) extending along at least a component normal to the plane (X, Y). The guide may be formed by an elongate opening in each chassis as depicted in FIG. 14. Alternatively, a rail, a gutter, a channel or a protrusion may form the guide. The guide (2r) must preferably extend in the direction perpendicular to the plane (X, Y) over a height at least equal to the difference in the radius (R) of the drum when it is in the fully open position (=maximum R) and the fully closed position (=minimum R). In a variant the guide (2r) is rectilinear and normal to the plane (X, Y) as depicted in FIGS. 3(a) to 3(d), 14, 15(a) and 15(b). Alternatively, the guide (2r) may also extend along a component parallel to the longitudinal axis (X). The guide (2r) may be rectilinear for example and extend transversely but not perpendicularly to the plane (X, Y) or may be curved as depicted in FIGS. 15(c) and 15(d).

[0151] As for the lever arm (2L) discussed above, if the plane (X, Y) is substantially horizontal the drum rests spontaneously on the rails by gravity. If the plane (X, Y) has a large vertical component the guide (2r) may be provided with a spring that pushes the drum against the rails.

Position of the Drum (2) Relative to the Cover (10)

[0152] The cover (10) may be arranged on the axle (2e) of the drum in two ways. The cover may come into contact with the rails [0153] either downstream of the drum which is therefore placed on the cover portion already deployed (cf. e.g., FIGS. 2(a) and 2(b)), [0154] or upstream of the drum which therefore rests directly on the rails or the adjacent surface (cf. e.g., FIGS. 2(c) and 2(d)).

[0155] The terms upstream and downstream are defined relative to the closing direction (Dc) of the movement in translation of the drum (2).

Cover/Rail Point of Contact Downstream of the Drum

[0156] As depicted in FIGS. 2(a), 2(b), 3(a), 3(b), and 4(a) to 4(c), 5 and 6, the cover (10) may come into contact with the rails and the surface downstream of the drum (2) in the closing direction (Dc). The insertion system, including the insertion pulley (32) must also be positioned downstream of the drum in order to enable the cover to cap the insertion pulley (32) and thus to insert the projecting elements into the opening (14) of the corresponding rails (6) before the drum (2) rolls on the cover portion thus extending downstream. This configuration is advantageous in the situation where the surface includes a cavity such as a swimming pool because, as the drum rests on the cover already placed and tensioned, the cover portion rolled onto the axle (2e) of the drum is not able to hang freely and where applicable to contact the water in the swimming pool before deploying or withdrawing the cover. This also protects the edges of the cover (10) that do not rest directly on the sundeck or on the rails.

Cover/Rail Contact Point Upstream of the Drum

[0157] As depicted in FIGS. 2(c), 2(d), 3(c), 3(d), 4(d), 7 and 13 to 15, the cover (10) may come into contact with the rails and the surface upstream of the drum (2) in the closing direction (Dc). The insertion system is therefore positioned upstream of the drum (2) in order to insert the projecting elements (12) in the opening of the rails or release them therefrom as the drum is moved. This variant has the advantage of simplifying the installation of the cover in the system for inserting the projecting element into the opening of the rail. The drum rests directly on the rails and/or on a portion of or on all of the width of the surface between the two rails, depending on whether the surface includes a cavity or not.

Insertion System

[0158] The insertion system of the device serves to engage and to disengage the projecting elements (12) as the drum is moved. It includes at least one insertion pulley (32) that enables insertion of the projecting element through the opening (14) into the space (14e). The insertion pulley is a pulley fixed in rotation to a chassis (23) enabling rotation of the pulley about a rotation axis that is preferably substantially parallel to the transverse axis (Y). The pulley is substantially aligned with the opening (14) of the corresponding rail and is preferably able to penetrate partially into the opening.

[0159] If the deployed cover must be tensioned in the direction of its width a tension must be applied to the cover in order to align the projecting element with the opening (14) before the insertion pulley is inserted in the opening. To this end the insertion system may include a tensioner (36) of the projecting element. As depicted in FIGS. 13 to 15 the tensioner (36) may take the form of a pair of parallel pulleys separated from one another by a distance greater than the thickness of the cover (10) and less than the minimum diameter of the projecting element (12). Accordingly, when the cover is inserted in the tensioner, the cover is able to slide freely between the two pulleys but it is not possible to extract the projecting element from between the two pulleys. The two pulleys of each tensioner (36) are coupled to a bonding chassis so that the rotation axes of the pulleys of the tensioner are coaxial and generally oriented in a plane normal to the plane (X, Y), parallel to the transverse axis (Y) and transverse to, not normal to, the plane (X, Y). Generally speaking, the rotation axes are angled between 20 and 70? inclusive, preferably between 30 and 60? inclusive, to the plane (X, Y) (cf. FIG. 14).

[0160] The insertion system may also include supplementary pulleys enabling best positioning of the projecting element (12) for inserting it into the opening (14) of the corresponding rail. For example, as depicted in FIG. 13, an alignment pulley (34) enables positioning of the projecting element in alignment with the other elements of the insertion system and orientation of the projecting element when it is inserted through the opening (14), as depicted in FIGS. 2(c), 2(d), 3(c), 3(d), 8(b), 13 to 15. The insertion system may also include an alignment roller (38) for controlling the trajectory of the projecting element (12) to pass through the opening (14) into the space (14e) under the best conditions. One example is depicted in FIG. 13. The exact configuration of the insertion system depends on the type of project element (12), the geometry of the opening (14), and the tension on the cover required in the direction of the transverse axis (Y) when the two edges are inserted into the openings (14) of the respective rails.

Projecting Elements (12)

[0161] The function of the projecting elements (12) is to enable reversible engagement and locking of the longitudinal edges of the cover (10) in the opening (14) and the space (14e) of the corresponding rails (6). The projecting element (12) may take the form of a continuous bead (cf. FIGS. 8, 9 and 14) or a coil spring (cf. FIG. 10) extending along the length of the cover (10). Alternatively, the projecting element (12) may take the form of a succession of discrete elements (12d) aligned on each longitudinal edge of the cover (cf. FIG. 11).

[0162] Locking is made possible by a locking system consisting of the projecting element (12) and the opening (14) and the space (14e) of the rails, the respective geometries of which enable engagement and locking of the longitudinal edges of the cover (10) in the opening (14) and the space (14e) of the rails when the drum is moved in the closing direction (Dc) and the unlocking and removal of the longitudinal edges of the cover (10) from the opening (14) and the space (14e) of the rails when the drum is moved in the opening direction (Do). A longitudinal edge of the cover is considered as locked in the opening of a rail if it cannot be removed therefrom only by the action of a force (F) applied parallel to the transverse direction (Y) in the direction of the surface to be covered (cf. FIG. 1).

[0163] A continuous bead preferably has a geometry characterized as follows [0164] in a section normal to each longitudinal edge of the cover the corresponding projecting element (12) defines a convex geometry, where a convex geometry is defined as a plane geometry defined by a closed perimeter that any straight cannot cross more than twice, [0165] in a cross section normal to the longitudinal axis (X) the opening (14) of the rail (6) has a maximum width (Lo) and the space (14e) has a maximum width (Le) greater than the maximum width (Lo) of the opening (14) (Lo<Le) where the maximum widths (Lo, Le) are measured parallel to the transverse axis (Y), and [0166] the projecting element (12) of each longitudinal edge and the groove of the corresponding rail are configured so that once inserted in the space (14e) by the insertion pulley (32) the projecting element occupying on its own the space (14e) cannot be removed therefrom by only the action of a force (F) applied parallel to the transverse axis (Y) in the direction of the surface to be covered.

[0167] Particular configurations of the projecting elements are described below. The present invention is not limited only to those configurations, which are provided by way of illustration.

Projecting Elements=Continuous Bead Characterized by D/d

[0168] In one variant of the invention the projecting element (12) is formed by a continuous bead extending along the longitudinal edges of the cover. An example of a continuous bead is described in WO2014064138. However, this bead necessitates the insertion of a belt into the space (14e) of the rail to lock the bead in the rail. In the case of the present invention it is preferable for the bead to be self-lockable, in that it does not necessitate any exterior elements to be locked reversibly in the opening and the space of the rail.

[0169] In the variant represented in FIGS. 8(a) to 8(d) the insertion system includes an insertion pulley (32) and an alignment pulley (34) depicted in FIG. 8(b) on which the interior surface of the cover comes to bear. The conjugate actions of the insertion pulley (32) and the alignment pulley (34) enable a precise required orientation to be imparted to the projecting element. The alignment pulley (34) is also fixed in rotation to the chassis (23) and is moved with the latter. The rotation axis of the alignment pulley (34) is preferably normal to the longitudinal axis (X) in order to enable the pulley to roll on the interior surface of the cover when the carriage is moved and thus to limit wear of the cover through rubbing. The rotation axis is also preferably transverse to the transverse axis (Y).

[0170] During movement in translation of the carriage in the closing direction (Dc) to deploy the cover over the surface (3) the insertion system including the insertion pulley (32) and the optional alignment pulley (34) enables insertion of the projecting element through the opening (14) by appropriately orienting the projecting element relative to the opening (14) and introducing it into the space (14e) in which it is locked by bearing on the internal walls of the space. During the movement in translation of the carriage in the opening direction (Do) to draw in the cover and to remove it from the surface the same insertion system enables re-orientation of the projecting element so that it is able to escape via the opening (14).

[0171] This variant varying the length/width ratio (D/d) of the projecting element (12) in which the length (D) is the maximum dimension of the cross section of the projecting element (12) and the width (d) is the minimum dimension thereof is simple to implement and enables reversible and reproducible locking of the longitudinal edges of the cover in the opening of the corresponding rails (6). The absence of moving parts (except for the rotating pulleys) increases the durability of the locking system.

Projecting Elements=Compressible Continuous Bead

[0172] In an alternative variant depicted in FIGS. 9(a) to 9(c) the projecting element (12) of each longitudinal edge is compressible so that it is able to go from a rest configuration to a compressed configuration. As depicted in FIG. 9(a), in the rest configuration the minimum diameter (d) of the projecting element is equal to do, which is between the maximum width (Lo) of the opening (14) and the maximum width (Le) of the space (14e) of the corresponding rail (Lo<d0<Le). As depicted in FIG. 9(b), in the rest configuration the projecting element (12) is therefore not able to pass through the opening (14). In the compressed configuration the minimum diameter (d) of the projecting element is equal to d1, which is less than or equal to the maximum width (Lo) of the opening (14) of the corresponding (d1?Lo<d0). The projecting element is therefore able to pass through the opening in its compressed configuration (cf. FIG. 9(b).

[0173] The insertion system enables compression of the projecting element (12) owing to its compressed configuration during its insertion through the opening (14) of the corresponding rail (6). As depicted in FIGS. 9(a) and 9(b) the insertion system includes an insertion pulley (32) mounted to rotate about an axis parallel to the transverse axis (Y) on the corresponding chassis (23). The insertion pulley (32) is positioned on the axis of the opening (14) adjacent to or even partially penetrating into the opening (14) and is moved with the drum (2). The insertion pulley (32) bears on the projecting element (12) of the cover and forces it to enter the opening (14). The projecting element is compressed by the conjugate action of the insertion pulley (32) which presses the projecting element against the opening of the rail and the width (Lo) of the opening in the rail that is insufficient to allow the passage of a projecting element of diameter (d0>Lo). Its diameter decreases until it becomes sufficiently small to enter the opening (14) when d1=Lo, as depicted in FIG. 9(b). Once the projecting element is in the space (14e) it returns to its rest configuration through its resilience. The longitudinal edge of the cover is therefore locked in the groove of the rail as depicted in FIG. 9(c).

[0174] The projecting element (12) can be removed from the space of the groove via the opening (14) by deforming it by the application of a traction force to the cover in a transverse direction preferably substantially normal to the plane (X, Y) to remove it from the space (14e) by forcing it to pass through the opening (14). On encountering the resistance offered by the opening of maximum width (Lo) to the passage of sections of the projecting element having a diameter greater than Lo the projecting element is compressed until the diameter (d1) of said section is at most equal to Lo and is therefore able to pass through the opening (14). The traction force may be applied by an alignment pulley (34) as discussed above with reference to FIG. 8(b). The extraction of the projecting element from the groove by compression can be facilitated by imparting to the projecting element a flared geometry at its point of attachment to the cover, as depicted in FIG. 9, that is to say not forming an acute angle to the cover.

[0175] The compressible projecting element (12) forms a convex bead that may be monolithic and solid or, as depicted in FIG. 9, have a core surrounded by an envelope. The core may be empty or filled with a material different from that of the envelope. The envelope may be formed of an extruded polymer, preferably an elastomer. Alternatively, the envelope may take the form of a woven material. In this case the core is preferably not empty but comprises a compressible foam or an elastomer.

[0176] Like the variant depicted in FIG. 8, the present variant includes no moving parts and is simple to produce. It enables reversible and reproducible locking of the longitudinal edges of the cover in the space (14e) of the corresponding rails (6).

Projecting Elements=Coil Spring

[0177] In a variant depicted in FIGS. 10(a) to 10(e) the projecting element on each longitudinal edge is a cable in the form of consecutive turns forming a coil spring the axis of which is parallel to the corresponding longitudinal edge of the cover (10). The turns are able to go from a rest configuration to a deformed configuration. As depicted in FIGS. 10(a), 10(c) and 10(d) in the rest configuration the minimum diameter (d) measured parallel to the transverse axis (Y) of each turn at rest is equal to do which is between the maximum width (Lo) of the opening (14) and the maximum width (Le) of the space (14e) of the corresponding rail (Lo<d0<Le). In its rest configuration a turn of the projecting element is not able to pass through the opening (14) of the groove.

[0178] As depicted in FIGS. 10(b) and 10(d) in the deformed configuration the angle between the deformed turns and the longitudinal axis (X) is modified so that the minimum diameter (d1) measured in a plane normal to the longitudinal axis (X) of each deformed turn is less than or equal to the maximum width (Lo) of the opening (14) of the corresponding rail (d1?Lo<d0). This is depicted in the view from above in FIG. 10(d) showing the turns in the middle that are deformed by changing their orientation so that the projection of the turns deformed in this way onto a plane normal to the longitudinal axis (X) has a minimum diameter (d1) less than or equal to the width (Lo) of the opening of the rail. In their deformed configuration the turns are therefore able to pass through the opening (14) of the corresponding rail.

[0179] During the movement in translation in the closing direction (Dc) the insertion system enables local deformation of the turns into their deformed configuration during their insertion through the opening (14) of the corresponding rail (6). The insertion system may include an insertion pulley (32) which, as in the variants depicted in FIGS. 8 and 9, may be mounted to rotate about an axis parallel to the transverse axis (Y) on the corresponding chassis (23). The insertion pulley (32) is positioned on the axis of the opening, adjacent to or even partially entering the opening (14) of the rail, and is moved with the drum (2). The insertion pulley (32) bears on turns of the projecting element (12) of the cover, deforming them into their deformed configuration and forcing them into the opening (14). While the insertion pulleys (32) discussed with reference to the variants depicted in FIGS. 8 and 9 preferably form a convex rounded rim in order to limit wear of the projecting element of the cover on which it bears, the insertion pulley (32) for changing the orientation of the turns until the deformed configuration of the present variant is achieved preferably has a beveled rim as depicted in FIGS. 10(a) and 10(b). The sharp edge formed by the beveled rim of the insertion pulley (32) penetrates between the turns and deforms them by turning them about an axis normal to the plane (X, Y). As depicted in FIG. 10(d) the turns deformed in this way are able to enter the space (14e) of the groove via the opening (14). FIG. 10(e) shows a lateral view of the turn by turn introduction of the coil spring into the space (14e) of a rail (6).

[0180] Once they are in the space (14e) the turns recover their rest configuration and the corresponding minimum diameter (do), which does not enable the turns to pass through the opening (14). The longitudinal edges of the cover are therefore locked into the corresponding rails.

[0181] Unlocking is effected in the same manner. During movement in translation of the drum in the opening direction (Do) to recover and roll the cover onto the axle (2e) of the drum the insertion pulley (32) penetrates between the turns accommodated in the space (14e) and causes them to pivot into the deformed configuration. The traction applied to the cover by the rotating drum is sufficient to extract the deformed turns through the opening (14) and thus progressively to release the longitudinal edges of the cover from the corresponding rails.

[0182] The cable in the form of consecutive turns forming a coil spring may be made of various materials. For example, the cable may be made of metal, such as stainless steel or an aluminum alloy. The metal and in particular the steel is preferably quenched or in any event sufficiently rigid not to be plastically deformed by the least stress, by stepping on it or the like. Once plastically deformed the turns can no longer serve to lock the longitudinal edges of the cover correctly. The cable may be made of a polymer or of a polymer reinforced with reinforcing fibers such as glass fibers, carbon fibers, natural fibers or aramide fibers (e.g., Kevlar?, Twaron?).

Projecting Elements=Discrete Hooks

[0183] In a variant depicted in FIGS. 11(a) to 11(c) the locking element includes a flange (6a) partially closing the side of the opening (14) of each rail (6) adjacent to the surface to be covered. The projecting element (12) is formed by a succession of discrete elements (12d). The latter form hooks preferably having an L profile or a j profile (with a lip at the bottom of the j). The profile includes a portion continuously aligned with the surface of the cover and fixed to the corresponding longitudinal edge of the cover and a transverse portion forming the hook, extending transversely relative to the aligned portion.

[0184] The hook is configured to hook onto the flange (6a) of the corresponding rail when the transverse tension applied to the cover by the insertion system is released. In the situation where the transverse portion of the discrete elements (12d) forming the hook includes a lip, as depicted in FIGS. 11(a) to 11(c), locking is assured. In the case of an L profile the angle between the aligned portion and the transverse portion may be slightly less than 90? in order to assure anchoring to the rail.

Opening and Closing of the Surface

[0185] As depicted in FIGS. 2, 3 and 5 to 7 the movement in translation of the drum necessitates activation of the rotation of the axle (2e) of the drum (2) to move the drum in the opening direction (Do), allowing the closing axle (1) to turn freely, in order to remove the cover from the surface. The activation of the rotation of the closing axle (1) is necessary to move the drum in the closing direction (Dc) allowing free rotation of the axle (2e) of the drum in order to deploy the cover over the surface. The rotation means (M1, M2) of the axle (2e) of the drum and the closing axle (1) are preferably electric motors. They may however be manual means comprising for example a crank. In FIGS. 5 to 7, when a rotation means (M1, M2) is activated it is represented with a lightning bolt alongside it. FIGS. 5 to 7 represent three variants discussed above. [0186] FIG. 5 represents the variant in which the closing axle (1) is mounted on the chassis (23) downstream of the drum (2); the projecting elements (12) are introduced into the opening of the rails downstream of the drum (2), which rolls on a cover portion already deployed downstream of the drum. [0187] FIG. 6 represents the variant in which the closing axle (1) is mounted on the first longitudinal edge of the surface (inserted in a gutter below the level of the edges adjacent to the surface; the projecting elements (12) are introduced into the opening of the rails downstream of the drum (2), which rolls on a cover portion already deployed downstream of the drum. [0188] FIG. 7 represents the variant in which the closing axle (1) is mounted on the chassis (23) downstream of the drum (2); the projecting elements (12) are introduced into the opening of the rails upstream of the drum (2), which rolls on the rails, deploying the cover upstream of the drum.

[0189] The variant in which the closing axle (1) is inserted inside the axle (2e) of the drum discussed above with reference to FIG. 4(c) is not represented because the operating principle is equivalent to that of the variants represented in FIGS. 5 and 7.

[0190] FIGS. 5(a), 6(a) and 7(a) represent the cover (10) entirely rolled up onto the drum (2), exposing the surface (3), represented by the cavity of a swimming pool. The drum (2) is stopped, parked at the level of the second width of the surface.

[0191] In order to cover the surface (3) it is necessary to move the drum (2) in the closing direction (Dc) as represented in FIGS. 5(b), 6(b) and 7(b). The first rotation means (M1) is activated (cf. lightning bolts alongside the motor (M1) in FIGS. 5(b), 6(b) and 7(b)). The rotation of the closing axle (1) rolls the first and second pull cords (21) around the latter, driving the movement in translation of the drum (2) in the closing direction (Dc). As the drum moves away from the second width of the surface, where the second transverse edge of the cover is fixed, the cover upstream of the drum is tensioned and creates a traction force spontaneously activating the rotation of the drum, which is free to rotate in this direction and therefore unrolls the cover (10) as the drum is moved in the closing direction (Dc). In FIGS. 5 and 7 the closing axle (1) is mounted on the chassis (23) and the fixed ends (21f) of the pull cords (21) are fixed to the corners of the surface at the level of the first width of the latter. In FIG. 6 the fixed ends (21f) of the pull cords (21) are fixed to the chassis (23) and the closing axle is located at the level of the first width. The effect of the rotation of the closing axle (1) is the same in all variants, since a traction force is created on the pull cords that drives the movement in translation of the drum in the closuring direction. The free rotation of the drum enables unrolling of the cover.

[0192] FIGS. 5(c), 6(c) and 7(c) represent the cover (10) entirely unrolled from the drum (2) and covering the surface (3). The drum (2) is stopped, parked at the level of the first width of the surface (on the side opposite the second width).

[0193] In order to uncover the surface (3) the drum (2) must be moved in the opening direction (Do) as represented in FIGS. 5(d), 6(d) and 7(d). The second rotation means (M2) is activated (cf. lightning bolts alongside the motor (M2) in FIGS. 5(d), 6(d) and 7(d)). The rotation of the axle (2e) of the drum drives the rolling of the cover around the axle (2e) which creates traction on the cover the second transverse edge of which is fixed at the second width. The drum is therefore pulled in the opening direction (Do) as the cover is rolled around the axle (2e). The closing axle (1) turns freely in this rotation direction and unrolls the pull cords (21), which are inserted in the openings (14) of the rails as the drum is moved.

[0194] As depicted in FIGS. 2, 3, 12, 13 and 15 the device may include at least first and second anti-lifting guides (25) including an external portion coupled to the corresponding first and second chassis and an internal portion inserted in the space of the corresponding rail so as to be able to slide freely along the rails parallel to the longitudinal axis (X) and not able to be extracted from the rails (14) by application of a force perpendicular to the longitudinal axis (X). In order to reduce friction during movement in translation of the anti-lifting guides on the rails the guides may include rollers (25r) enabling rolling on the rails. As depicted in FIG. 12 the rollers may rest on external surfaces of the rails. In an alternative variant the rollers may be in the space (14e) of the rails. The anti-lifting guides are useful if the plane (X, Y) is not horizontal or is even substantially vertical. But they are equally useful in the situation where the plane (X, Y) is horizontal because if the wind gusts under the cover during the movement in translation of the drum it can lift the drum and misalign the device.

CONCLUDING REMARKS

[0195] The use of two motors (M1, M2) intuitively appears a great constraint than using a single motor as described in WO2010054960. In reality this is not the case. A motor is cheap and can be inserted in the closing axle (1) and drum axle (2e) without taking up any additional space. The use of two motors (M1, M2) makes it possible to dispense with a torsion spring that is indispensable in the case of a single motor to activate the rotation of the drum and the unrolling of the cover during the deployment of the cover as the drum is moved in the closing direction (Dc). The torsion spring has some disadvantages. On the one hand the torsion spring considerably increases the work to be done by the motor on removing the cover, since the motor must not only move the drum and roll the cover but also tension the torsion spring. On the other hand, mounting and adjusting the torsion spring requires some experience and cannot be effected for the first time by the person acquiring a covering device.

[0196] The device of the present invention can therefore use less powerful motors than in the case of a system with a torsion spring. A device of this kind comprises fewer moving parts and is therefore cheaper. It is also easier to install and it is possible to imagine users installing the device themselves. At the same time, with the insertion system enabling locking of the longitudinal edges in the openings of the rails, without using for locking moving parts or third-party components, such as flexible belts inserted in the opening of the rails, the device in accordance with the present invention offers a simple and robust solution for covering and uncovering a surface with the cover secured on its four sides, which is advantageous and in some countries and legally required in the case of swimming pools.

TABLE-US-00001 REF FEATURE 1 Closing axle 2 Drum 2e Axle of drum 2L Lever arm 2r Guide 3 Surface to be covered 6 Rail 6a Flange of rail 10 Cover 10f Second transverse edge of cover 10m First transverse edge of cover 12 Projecting element 14 Opening of rail 14e Space of rail 21 Pull cord 21f Fixed end of pull cord 21m Mobile end of pull cord 23 Chassis 25 Anti-lifting guide 25r Roller of anti-lifting guide 31 Idler pulley of pull cord 32 Insertion pulley of projecting element 34 Alignment pulley of projecting element 36 Tensioner of projecting element 38 Alignment roller of cover 12d Discrete elements d Minimum diameter of projecting element (measured normal to longitudinal edge) d0 Minimum diameter of projecting element in rest configuration (measured normal to longitudinal edge) d1 Minimum diameter of projecting element not in rest configuration (measured normal to longitudinal edge) D Maximum diameter of projecting element F Force applied parallel to transverse axis (Y) Le Maximum width of space (measured parallel to Y) Lo Minimum width of opening (measured parallel to Y) M1 First rotation means of closing axle (e.g. motor) M2 Second rotation means of drum (e.g. motor) R Radius of drum (varies according to portion of cover rolled around axle (2e) X Longitudinal axis Y Transverse axis