CN101111402A - Darkening devices for motor vehicles - Google Patents

Abstract

The invention relates to a darkening device (1) comprising a roller blind material (10), wherein the two opposite ends (11, 12) thereof are respectively connected to a winding tube (30) and a traction rod (30), wherein the roller blind material (10) is moveably mounted for displacement between a receiving position and an extended position, wherein the darkening device (1) also comprises an element (40a, 40b) that is suitable for coupling the displacement of the traction rod (30) to the axial rotation of the winding tube (20). The invention is characterized in that each coupling element (40a, 40b) comprises at least one elastic means of return (41a, 41b) which can tense the roller blind material (10) in a longitudinal direction between the traction rod (30) and the winding tube (20), forming an integral part of the transmission chain, ensuring the coupling of the traction rod (30) to the winding tube (20) for the purpose of displacement.

Description

Darkening devices for motor vehicles

technical field

The invention relates to a device for at least partially covering one or more transparent panes with a shade.

The invention can be used particularly advantageously, but not exclusively, in the field of motor vehicles.

Background technique

Currently, the roofs of motor vehicles are increasingly being equipped with transparent or translucent panes. Typically, this is a sliding roof system with movable panes made of glass, or fixed glass panes that directly form about the majority of the roof.

Regardless of the embodiments, in practice more or less transparent panes of this type are used systematically in combination with light-darkening means adapted to extend parallel to the inner surface of the glass pane. This device is designed to prevent light passing through the glass pane from traveling to the interior of the vehicle. Of course, the aim is to limit the greenhouse effect in motor vehicles during the day with strong solar radiation.

Darkening devices known in the prior art include devices that achieve their function through the use of curtains with retracting devices. Roughly speaking, a more or less transparent linen for displacement relative to the area to be darkened is mounted movable between a receiving position and an extended position. More precisely, opposite ends of the linen or shade fabric are permanently attached to a retractor tube mounted pivotally and spaced apart from the area to be darkened, respectively, and to a tie rod , the tie rod is mounted to be able to move along said area to be darkened to achieve displacement. The overall configuration is such that the linen or shade fabric is wound up on the take-up tube in the receiving position and stretches under the area to be darkened in the pulling position.

In this embodiment, the take-up tube is typically not mounted completely free to pivot, but is coupled to a torsion spring that permanently urges the take-up tube in the direction of take-up of the linen or shade fabric. The purpose here is to tension the linen or shade fabric longitudinally between the pull rod and the take-up tube when the linen fabric or shade fabric is pulled. Regardless of this, this construction has the disadvantage of being able to function only when the drawbar is fully blocked.

In the case of a purely manual device, this means that the pull rod must be hooked in order for the darkening function to be effective. Thus, it appears that, besides the receiving position, there is in fact only one use position actually usable, in particular the pulling position. The end result is that this means that this all-or-nothing functionality makes the darkening device unsatisfactory in practice.

Of course, motor-driven darkening devices can solve this problem. a driving device comprising a plurality of positions and driving two cables attached respectively to the two ends of the pull rod, in fact fully capable of moving the linen or shade fabric between the receiving position and the pulling position, and capable of blocking the pull rod, Regardless of the position of the linen and blackout fabric relative to the area to be darkened. However, this configuration is extremely expensive compared to manual darkening devices; this makes its use impossible for many applications.

There is also known a darkening device which is manually actuated and which is able to provide several positions and is therefore suitable to overcome all these difficulties. This device, capable of providing multiple positions, differs from its manual counterpart described above in that it does not have any return spring at all in the area of the take-up tube, but instead has Element adapted to link the displacement of the pull rod with the pivoting of the retractor tube when shifting between pulling positions.

In particular, each end of the pull rod is permanently connected to a cable which interacts in a driving manner with a tapered roller which is partially connected to a respective end of the take-up tube. The tapered shape of each roller is necessary so that the pull rod has a usable displacement path corresponding to the retracted or unrolled length of the linen or shade fabric to ensure that the linen or shade fabric can be moved between the pull rod and the take-up tube in all positions. obtain constant tension. This means, of course, that each tapered roller must be shaped such that the diameter of the linen wound on the take-up tube always corresponds to the diameter of each cable wound on the roller in which The diameter of the linen fabric depends on the number of turns of the take-up tube.

However, this type of darkening device has the disadvantage of being very bulky since the tapered rollers generally have an excessively large path in transverse direction; this therefore reduces the width of the area supposed to be darkened. As designed, the width of each roller is in fact directly proportional to the number of turns required by the take-up tube to fully wind up the linen or shade; this means that as the length of the linen or shade increases, It gets bigger and bigger.

Contents of the invention

The technical purpose to be achieved by the subject of the present invention is therefore to propose a darkening device having a shade fabric with two opposite ends permanently connected to a take-up tube and a pull rod respectively, said roll The receiving tube is installed to be able to rotate around the shaft and is spaced from the area to be darkened, the pull rod is installed to be able to move along the area to be darkened to realize displacement, and the light-shielding fabric is installed to be able to move in the darkened area. The displacement is achieved by moving between a receiving position where the shade fabric is wound on the take-up tube and a pull position where the shade fabric is stretched under the area to be darkened, the darkening The device also has at least one part adapted to couple the displacement of the pull rod to the pivoting of the take-up tube when the shade fabric is driven to be displaced between the receiving position and the pulling position, and the dark The darkening means have a significantly improved compact shape on either side laterally of the area to be darkened and at the same time have particularly low manufacturing costs, so that the problems of the prior art can be avoided.

As claimed in the present invention, the above-mentioned technical purpose is achieved in that each coupling part has at least one elastic reset element, which is suitable for longitudinally tensioning the shade fabric between the pull rod and the retracting tube, and the reset element constitutes a transmission Constituent member of the chain that ensures the coupling of the pull rod to the retractor tube for displacement.

The fact that the elastic return element constitutes an integral part of the transmission chain means that when the pull rod is coupled to the retractor tube for displacement, the elastic return element works directly and effectively at the same time. This means that it interacts directly with other movable elements that make up the power transmission element and drive train to achieve displacement.

In particular, the presence of each elastic return element equalizes the difference between the retracted and unfolded lengths of the pull rod and the retracted and deployed lengths of the shade fabric, wherein the displacement path is a priori constant over time, the shade The roll-up and roll-out length of the fabric varies in part with the number of revolutions of the roll-up tube.

The invention defined in this way offers, on the one hand, the advantage of enabling a plurality of positions of operation and, on the other hand, is fully compatible with purely manual operation. By eliminating the bulky tapered rollers of the prior art, the present invention also minimizes the space requirements of the darkening device on either side laterally of the area to be darkened, whereby, for a device of a given size , which maximizes the darkened area. Regardless of the embodiment, the invention also has the advantage of a relatively simple structure; this makes it less expensive than equivalent systems according to the prior art.

The invention also relates to features which will become apparent from the following description and must be considered individually in all possible technical combinations.

Description of drawings

The description given by way of non-limiting examples makes it easier to understand what the invention consists of and how it can be implemented. The description also refers to the accompanying drawings, which include:

Figures 1 to 5 show schematic diagrams of five darkening devices according to the following five different embodiments.

Detailed ways

For the sake of clarity, the same components are designated with the same reference numerals. Furthermore, only components important to the understanding of the invention are shown, and not to scale but in schematic form only.

Figure 1 shows a darkening device 1 designed to be installed in the interior area of a motor vehicle for the purpose of darkening the light passing through a fixed pane of glass forming the roof skin. It should be noted that the area to be darkened is here formed by the actually transparent part of the pane of glass and is thus actually able to allow light to enter the interior of the passenger space without facing any part of the vehicle body or any component of the interior equipment part.

Regardless of this, the darkening device 1 firstly has an opaque shade fabric 10, one of its two opposite ends 11, 12 permanently connected to a retracting tube 20 and the other to a pull rod 30, wherein the retracting tube 20 is spaced from the area to be darkened and is mounted to be rotatable about an axis, and the tie rod 30 is mounted to be movable along said area to be darkened to achieve displacement.

In order to be pulled parallel to the inner surface of the glass pane, the shade fabric 10 is mounted to be movable between a receiving position and a pulling position. In the receiving position, the shade fabric 10 is rolled up on the take-up tube. position, the shade fabric 10 stretches under the area to be darkened.

The darkening device 1 is also provided with two parts 40a, 40b capable of coupling the displacement of the pull rod 30 to the roll when the linen 10 is driven to be displaced between the receiving position and the pulling position. The axis rotation of receiving pipe 20.

According to the subject of the invention, each coupling part 40a, 40b has a corresponding elastic return element 41a, 41b which enables the longitudinal tensioning of the shade fabric 10 between the pull rod 30 and the take-up tube 20 and constitutes an integral part of the transmission chain , the drive chain ensures that the pull rod 30 is coupled to the retracting tube 20 for displacement.

In this particular embodiment, chosen only as an example, the coupling members 40a, 40b are able to connect the respective ends 31, 40b of the pull rod 30, respectively, when the shade fabric 10 is driven to be displaced between the receiving position and the pulling position. 32 are coupled to respective ends 21, 22 of the retracting tube 20 for displacement. This feature makes it possible, advantageously, to guide the displacement of the pull rods 30 in a completely symmetrical manner, ie thus without requiring any transverse positioning that could hinder the correct pulling of the shade fabric 10 .

According to an inventive feature, each coupling part 40a, 40b has a respective flexible power transmission element 42a, 42b connected to the tie rod 30 and adapted to interact in a driving manner with a respective rotational power transmission element 43a, 43b, rotating The power transmission elements 43a, 43b are connected to the retracting tube 20 .

In this first embodiment of the invention, the darkening device 1 is actuated by hand; this has the advantage of an extremely simple construction as a whole. In addition, the respective flexible power transmission element 42a, 42b of each coupling part 40a, 40b is connected to the tie rod 30 via a respective elastic return element 41a, 41b capable of Tensile force is applied between 42a, 42b and the pull rod 30 .

In this embodiment, the elastic return elements 41a, 41b incorporated in the respective coupling parts 40a, 40b are formed by cylindrical tension springs, one end of which is permanently connected to the flexible power transmission elements 42a, 42b , and the other end is permanently connected to the tie rod 30.

It should be noted that FIG. 1 is a simple schematic representation and that each elastic return element 41a, 41b is actually advantageously integrally formed in the inner region of the tie rod 30, obviously due to space requirements and aesthetic considerations.

Each rotary power transmission element 43a, 43b is partly formed by a roller which can interact in a retracting action with a flexible power transmission element 42a, 42b of a priori selectable shape, since the two The mutual drive between the elements occurs through friction.

It should be noted that each roller, here rigid, is permanently connected to a respective end 21 , 22 of the take-up tube 20 . However, this connection can also be established via a second elastic return element, which has an effect which would then add to that of the cylindrical tension springs forming the elastic return elements 41a, 41b. Regardless of this, the unit consisting of the retracting tube 20 and the two rotary power transmission elements 43a, 43b is here mounted rotatable relative to the fixed bearings 60a, 60b.

The flexible power transmission element 42a, 42b partly has a rectilinear shape, ie it has two separate ends, one connected to the tie rod 30 and the other connected to the rotary power transmission element 43a, 43b. For example, the flexible power transmission elements 42a, 42b may thus be formed by cables or belts. Of course, clearly, in this first embodiment, the connection between the end of each flexible power transmission element 42a, 42b and the tie rod 30 is indirect, since the connection is via the elastic return element 41a, 41b establishes that in this case the elastic return element is a cylindrical compression spring.

In this embodiment, it should also be noted that the end of each flexible power transmission element 42a, 42b designed to interact in a driving manner with a respective rotary power transmission element 43a, 43b is permanently connected to the respective The power transmission elements 43a, 43b are rotated. This simply means that the ends do not have the form of dead ends like the third embodiment in Figure 3 described below. It should also be noted that, in a conventional manner, two deflection rollers 44a, 44b are included in the displacement kinematics of each flexible power transmission element 42a, 42b.

According to a form not shown in the first embodiment, each flexible power transmission element 42a, 42b may have the form of a ring connected on the one hand to the tie rod 30 and on the other hand connected in driving manner to the corresponding rotary power transmission element 43a, 43b. In addition, each flexible power transmission element 42a, 42b also has a plurality of protrusions regularly distributed along the length and capable of engaging with the corresponding side along the shade fabric 10 by engaging at the height of the area to be darkened. Edge-disposed holes of substantially complementary cross-section interact. This feature has the advantage of enabling the shade fabric 10 to be supported laterally as it is stretched under the area to be darkened.

Regardless of this, it is important to note that this characteristic means that each flexible power transfer element 42a, 42b has the shape of a ring. In fact it is important that the part of the flexible power transmission element 42a, 42b in the area to be darkened always moves parallel to the shade fabric 10 so that the two can remain permanently connected to each other.

Fig. 2 shows a darkening device 100 corresponding to a second embodiment of the present invention. Although manually operated as before, the darkening device 100 differs from the first described embodiment mainly in the following way: The corresponding rotary power transmission element 143a, 143b of each coupling part 140a, 140b is here reset via a corresponding elastic The elements 141 a , 141 b are connected to the retraction tube 20 , the elastic return elements 141 a , 141 b are able to apply a torsion between the rotational power transmission elements 143 a , 143 b and the retraction tube 20 .

In other words, this means that each rotary power transmission element 143a, 143b is pivotably connected to the retracting tube 20 via a corresponding elastic return element 141a, 141b which enables staggered by a certain angle. Overall is configured such that the axis of rotation of each rotary power transmission element 143 a , 143 b is collinear with the axis of rotation of the retractor tube 20 . Of course, the angular displacement between each rotary power transmission element 143a, 143b and the retracting tube 20 is continuously subjected to the reset action exerted by the corresponding elastic reset element 141a, 141b. Despite this internal mobility, the unit consisting of the retracting tube 20 and the two rotating power transmission elements 143a, 143b is mounted so as to be movable relative to the fixed bearings 160a, 160b.

In this embodiment, the respective elastic return element 141a, 141b of each coupling part 140a, 140b is formed by a helical spring permanently connected at one end to the rotary power transmission mechanism 143a, 143b and at the other end to the retracting Tube 20.

It may be noted that, like the first embodiment, each rotary power transmission element 143a, 143b is formed by a roller capable of interacting with a rectilinear flexible power transmission element 142a, 142b in a retracting action. It should be noted that, in like manner, each flexible power transfer element 142a, 142b has a generally smooth profile and an end directly and permanently connected to the rotary power transfer element 143a, 143b. Furthermore, here too there are two known deflection rollers 144a, 144b, which are respectively included in the displacement kinematics of each flexible power transmission element 142a, 142b.

Here in the specification, it should be pointed out that it is entirely conceivable to combine the functions of the elastic return elements 141a, 141b with the functions of the elastic return elements 41a, 41b used in the darkening device 1 .

Fig. 3 shows a darkening device 200 according to a third embodiment of the present invention. Compared with the two previously described embodiments, the most important difference of this embodiment is that the darkening device 200 has a motor device 250 capable of driving the shade fabric 10 between a receiving position and a pulling position to achieve shift. The motor arrangement may have a lower torque compared to the motor of existing retractors with a return spring in the retraction tube.

Particularly advantageously, the motor arrangement 250 is here able to drive the respective movable power transmission element 242a, 242b, 243a, 243b of each coupling part 240a, 240b for displacement. Clearly, the movable power transmission elements 242a, 242b, 243a, 243b may be arbitrarily designated as flexible power transmission elements 242a, 242b or as rotational power transmission elements 243a, 243b.

In this embodiment, roughly speaking, the motor arrangement 250 has an electric motor, not shown for the sake of clarity, which is adapted to rotate two driving pinions 251 with spur teeth additionally shown in FIG. 3 . Overall is configured such that each drive pinion 251 can drive interact with a respective flexible power transmission element 242a, 242b of each coupling part 240a, 240b.

The darkening device 200 also differs from its manually operated counterpart in that each rotary power transmission element 243a, 243b is formed by a pinion which can interact by meshing with a toothed flexible power transmission element 242a, 242b.

For example, the flexible power transmission elements 242a, 242b may be formed by toothed belts or by rack-shaped cables, in particular of the side pull or solid cast type. Especially with regard to the latter, the cables may be steel cables, polyester or Kevlar braids, the balls or teeth are solidly cast at constant intervals on the steel cables, polyester or kevlar in the area where they are acted upon (opening or closing action) in mesh with the pinion. Ester or Kevlar braid. The cable may not have teeth in other areas.

Each flexible power transfer element 242a, 242b also has a rectilinear shape, connected at one end to the tie rod 30 and at the other end to the respective power transfer element 243a, 243b; the other end here terminates with a dead end cable.

In addition, the structure of the coupling parts 240a, 240b is substantially comparable to that used in the darkening device 1, especially in terms of the configuration and operation of the elastic return elements 241a, 241b. Also, two paired turning rollers 244a, 244b are used in a conventional manner.

Fig. 4 shows a darkening device 300 corresponding to the fourth embodiment of the present invention. It substantially differs from the third embodiment in that the respective rotary power transmission element 343a, 343b of each coupling part 340a, 340b has here the shape of a ring, which is connected to the tie rod 30 on the one hand and used to communicate with the corresponding The rotating power transmission elements 343a, 343b of the interact for driving.

Not each flexible power transmission element 342a, 342b is directly and permanently connected to the tie rod 30 due to the use of the elastic return element 341a, 341b of the respective coupling element 340a, 340b between the flexible power transmission element and the tie rod 30 , so that a pulling force can be applied between the two. The elastic restoring element is here a cylindrical tension spring.

With regard to the coupling parts 340a, 340b, in particular, there is also here a pinion forming a rotary power transmission element 343a, 343b capable of interacting by meshing with a toothed belt, which The toothed belt forms a toothed flexible power transmission element 242a, 242b. In the same way as the third embodiment, each coupling part 340a, 340b can be driven by the gear 351 of the motor means 350 to effectuate the translation. The translation element is a flexible power transmission element 342a, 342b. Likewise, paired deflection rollers 344a, 344b are required for the kinematic mechanism of the flexible power transmission elements 342a, 342b.

According to a form of this fourth embodiment not shown, the teeth provided along each flexible power transmission element 342a, 342b can be engaged by engagement with teeth of substantially complementary cross-section provided along the corresponding side edges of the shade fabric 10. , wherein each flexible power transmission element 342a, 342b is in the form of a ring and is provided with teeth in the area to be darkened. This feature has the advantage of enabling the shade fabric 10 to be supported laterally as it is stretched over the area to be darkened.

It is important to note that in any case this feature means that each toothed flexible power transmission element 342a, 342b has the shape of a ring. In fact, it is important that the part of the flexible power transfer element 342a, 342b in the area to be darkened always runs parallel to the shade fabric 10, so that the flexible power transfer element and the shade fabric remain virtually permanently connected.

Fig. 5 shows a darkening device 400 according to a fifth embodiment of the present invention. This is particularly reminiscent of the fourth embodiment described above. However, the difference is that the corresponding rotary power transmission element 443a, 443b of each coupling part 440a, 440b is connected to the retracting tube 20 by means of an elastic reset element 441a, 441b, which can rotate the power transmission element Torsion is applied between 443a and the retracting tube 20 . In this sense, it is also similar to the darkening device 100 that is the subject of the second embodiment of the invention.

Of course, the invention relates generally to a motor vehicle, which is equipped with at least one obscuring device 1 , 100 , 200 , 300 , 400 as described above.

Claims (17)

CLAIMS 1. A darkening device (1, 100, 200, 300, 400) having a shade fabric (10) with two opposite ends (11, 12) which are respectively permanently Connected to the retracting tube (20) and the pull rod (30), the retracting tube is installed to be able to rotate around the axis and is spaced from the area to be darkened, and the pull rod is installed to be able to be darkened along the The area of the shading fabric (10) is rolled up to shift between the receiving position and the stretched position to realize the displacement. In the receiving position, the shading fabric (10) is rolled up on the take-up tube (20), In the extended position, the shade fabric (10) is stretched under the area to be darkened, the darkening device (1, 100, 200, 300, 400) also has at least one coupling part (40a, 40b, 140a, 140b, 240a , 240b, 340a, 340b, 440a, 440b), when the shade fabric (10) is driven to shift between the receiving position and the pulling position, the at least one coupling part is adapted to displace the pull rod (30) Coupling to the pivoting of the retracting tube (20), characterized in that each coupling part (40a, 40b, 140a, 140b, 240a, 240b, 340a, 340b, 440a, 440b) has at least one elastic return element (41a , 41b, 141a, 141b, 241a, 241b, 341a, 341b, 441a, 441b), the at least one elastic return element makes the shade fabric (10) longitudinally tensioned between the pull rod (30) and the retracting tube (20) , and constitute a constituent member of a drive chain that ensures that the pull rod (30) is coupled to the retracting tube (20) to achieve displacement. 2. The darkening device (1, 100, 200, 300, 400) according to claim 1, characterized in that it comprises two coupling parts (40a, 40b, 140a, 140b, 240a, 240b, 340a, 340b , 440a, 440b), when the shade fabric (10) is driven to shift between the receiving position and the pulling position, the two coupling parts respectively couple the corresponding ends (31, 32) of the pull rod (30) to the respective ends (21, 22) of the retracting tube (20) to effect displacement. 3. The darkening device (1, 100, 200, 300, 400) according to claim 1 or 2, characterized in that each coupling member (40a, 40b, 140a, 140b, 240a, 240b, 340a, 340b , 440a, 440b) includes a flexible power transmission element (42a, 42b, 142a, 142b, 242a, 242b, 342a, 342b, 442a, 442b) connected to the tie rod (30), and Interacts for drive with a rotary power transmission element (43a, 43b, 143a, 143b, 243a, 243b, 343a, 343b, 443a, 443b) connected to the retractor tube (20). 4. The darkening device (1, 200, 300) according to claim 3, characterized in that each flexible power transmission element (42a, 42b, 142a, 142b, 242a, 242b, 342a, 342b, 442a, 442b) is connected to the pull rod (30) through elastic return elements (41a, 41b, 241a, 241b, 341a, 341b) which A pulling force is applied between the pull rod (30). 5. The darkening device (1, 200, 300) according to claim 4, characterized in that the elastic return elements (41a, 41b, 241a, 241b, 341a, 341b) are formed by cylindrical tension springs, said One end of the tension spring is permanently connected to the flexible power transmission element (42a, 42b, 242a, 242b, 342a, 342b) and the other end is permanently connected to the tie rod (30). 6. The darkening device (100, 400) according to claim 3, characterized in that, each rotating power transmission element (143a, 143b, 443a, 443b) passes through the elastic return element (141a, 141b, 441a, 441b) Connected to the retracting tube (20), the elastic return element exerts torsion between the rotating power transmission elements (143a, 143b, 443a, 443b) and the retracting tube (20). 7. The darkening device (100, 400) according to claim 6, characterized in that the elastic return element (141a, 141b, 441a, 441b) is formed by a helical spring, one end of which is permanently connected to the rotational power The other end of the transmission element (143a, 143b, 443a, 443b) is connected to the retracting tube (20). 8. The darkening device (1, 100, 200) according to any one of claims 3 to 7, characterized in that each flexible power transmission element (42a, 42b, 142a, 142b, 242a, 242b) has A rectilinear shape with one end permanently attached to the tie rod (30) and the other end attached to the rotating power transmission element (43a, 43b, 143a, 143b, 243a, 243b). 9. The darkening device (200) of claim 8, wherein each flexible power transmission element (242a, 242b) interacts with a corresponding rotary power transmission element (243a, 243b) for driving The end of the cable terminates in the form of a dead end cable. 10. The darkening device (1, 100) according to claim 8, characterized in that each flexible power transmission element interacting with the rotary power transmission element (43a, 43b, 143a, 143b) for driving (42a, 42b, 142a, 142b) are permanently connected to the rotary power transmission element (43a, 43b, 143a, 143b). 11. The darkening device (300, 400) according to any one of claims 3 to 7, characterized in that each flexible power transmission element (342a, 342b, 442a, 442b) has the shape of a ring, one of On the one hand it is connected to the tie rod (30) and on the other hand it interacts with the corresponding rotary power transmission element (343a, 343b, 443a, 443b) for driving. 12. The darkening device (200, 300, 400) according to any one of claims 3 to 11, characterized in that each rotary power transmission element (243a, 243b, 343a, 343b, 443a, 443b) comprises a small A gear, said pinion adapted to interact by meshing with a toothed flexible power transmission element (242a, 242b, 342a, 342b, 442a, 442b). 13. The darkening device (300, 400) according to claim 12, characterized in that each toothed flexible power transmission element (342a, 342b, 442a, 442b) has the shape of a ring which on the one hand connects to the tie rod (30), on the other hand interacts with the corresponding rotary power transmission element (343a, 343b, 443a, 443b) for driving, and along each flexible power transmission element (342a, 342b, 442a, 442b ) provided teeth capable of interacting by engaging with holes of substantially complementary cross-section provided along the respective side edges of the shade fabric (10), said each flexible power transmission element being provided with teeth in the area to be darkened . 14. A darkening device (1, 100) according to any one of claims 3 to 11, characterized in that each rotary power transmission element (43a, 43b, 143a, 143b) comprises a roller which is connected to a Flexible power transfer elements (42a, 42b, 142a, 142b) of any shape interact to effect retraction. 15. The darkening device (1, 100) according to claim 14, characterized in that each flexible power transmission element (42a, 42b, 142a, 142b) has the shape of a ring connected on the one hand to a tie rod ( 30), on the other hand interacts with the corresponding rotary power transmission element (43a, 43b, 143a, 143b) for driving, and the flexible power transmission element (42a, 42b, 142a, 142b) has a plurality of protrusions, The protrusions are regularly distributed along the length and interact with holes of substantially complementary cross-section provided along respective side edges of the shade fabric (10) by engaging at the height of the area to be darkened. 16. A darkening device (200, 300, 400) according to any one of claims 1 to 15, characterized in that it comprises motor means (250, 350, 450) which drive the shade fabric (10 ) to displace the shade fabric (10) between the receiving position and the pulling position. 17. The darkening device (200, 300, 400) according to claim 16, characterized in that motor means (250, 350, 450) for effecting the displacement drive each coupling member (240a, 240b, 340a , 340b, 440a, 440b) of the movable power transmission element (242a, 242b, 243a, 243b, 342a, 342b, 343a, 343b, 442a, 442b, 443a, 443b).

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