"A translucent multiwall sheet assembly, particularly for skylights"

Description

This invention relates to a translucent multiwall sheet assembly, particularly for use in the construction of skylights and canopies of shopping malls, industrial plants, indoor gyms, swimming pools and other premises where a good natural lighting is desired.

Multiwall sheets made of glass or of a translucent synthetic material such as acrylic or polycarbonate have been used for some time for glazing canopies and skylights, and are available as either flat or curved plates. The multiwall construc- tion, obtained by extrusion, gives the sheet a strong though lightweight quality, and also contributes to soften the light entering through the skylight. However, the amount of daylight they let into the room is not adjustable, and consequently the lighting afforded by such a skylight on sunny days often turns out to be glaring and uncomfortable. The material of the multiwall sheet can of course be tinted for shading purposes, but the shading may become undesirable on cloudy days. Where an adjustable lighting is regarded as necessary, screens or awnings have been installed beneath the skylight, but such a construction is cumbersome, expensive, difficult to implement with curved plates, and requires frequent cleaning.

It is therefore a main object of the invention to provide a translucent multiwall sheet assembly that can be adjusted in the degree of overall transmission of daylight.

Another object is to provide such sheet assembly in both flat and curved constructions.

A further object is to provide such sheet assembly without requiring changes to the conventional multiwall sheet or to the extrusion process by which conventional multiwall sheets are manufactured.

The above-mentioned objects, as well as other objects and advantages, such as will appear from the following description, are achieved by the invention by providing a translucent multiwall sheet assembly having the features recited in claim 1.

The dependent claims state other innovative features of the invention.

The invention will now be described in more detail, with reference to the attached drawings, shown by way of nonlimiting examples, wherein:

Fig. 1 is a perspective view in cross-section of a translucent twin-wall sheet assembly according to a preferred embodiment of the invention;

Fig. 2 is a view to an enlarged scale and in longitudinal cross-section of an end portion of a twin-wall sheet assembly according to the preferred embodiment of the invention, with portions broken away;

Fig. 3 is a plan view in cross-section made at IH-III on Fig. 2, at a smaller scale;

Fig. 4 is a view in longitudinal cross-section of another example of a twin-wall sheet assembly according to the invention.

In Fig. 1, a polycarbonate twin-wall sheet 10 comprises two parallel walls 11, 12, which are joined with each other by a plurality of parallel, transverse webs 14, so that a plurality of rectangular-profile tunnels such as 16 are defined between the webs. The twin-wall sheet is manufactured by a conventional extrusion process as known in the art and is commercially available.

According to the invention, a first or lower flat, elongated strip or band 18, made from an at least partly opaque, flexible material, is received in each tunnel along its entire length. As shown on Fig. 2, strip 18 is punched with a fixed-pitch series of substantially rectangular apertures such as 20. The gap between any two apertures 20 is equal or slightly larger than the width of an aperture, i.e. than the dimension of an aperture in the longitudinal direction of the tunnel.

A second or upper strip 24 is similar to strip 18 and is also freely received in each tunnel above lower strip 18. The upper strip 24 has the same width as lower strip 18 and is punched with apertures 26 of the same size and at the same pitch.

As shown on Fig. 2 and 3, a housing 28 is attached along one end side of the twin- wall sheet 10, comprising two aluminum profiled pieces 30, 32 that are swaged together to clamp the twin-wall sheet.

Each lower strip 18 is fastened at one end to the base of its respective tunnel 16, as by a screw or rivet 22. Each upper strip 24 is arranged slidably above a respective lower strip 18 and is cut at one end with an oblique slot 34, preferably at 45° to the longitudinal direction of the strip.

A slide guide 36 extends along the housing transversely to the tunnels, and slidably houses a stick or slat 38 provided with pins 40 located for freely engaging respective slots 34. Spacers 42 are arranged around pins 40 between strip 24 and slat 38.

A knob 44 has a projection that passes through a slot 46 in the housing and is threaded into one of pins 40, so that stick 38 can be displaced within guide 36 by moving the knob, thereby causing all the upper strips to be displaced in one or the other direction along the tunnels by a desired amount.

By moving the knob, a user can therefore either align the apertures of the upper strips with the apertures of the lower for maximum daylight transmission through the strips, or, alternately, bring the apertures out of alignment so that the solid portions of each strip shut the apertures in the adjacent strip. Any intermediate condition, i.e. one that leaves only a fraction of each aperture uncovered, may also be obtained. It can be seen that a desired degree of shading can be achieved, in a range from maximum light screening, when the apertures are fully shut, to minimum screening, when the apertures are fully open.

On Fig. 4, the twin-wall sheet, the housing for the driving means, and the arrangement of opaque, apertured strips are substantially the same as on Figs. 1 to 3, and bear the same reference numbers. However, in this embodiment the driving means for the upper strips comprise a short rack 50, attached to the end of each upper strip 24 and engaging a pinion 52 extending along the mouths of tunnels 16 and journaled at both ends, and provided with an operating knob (not shown) for moving the racks to and fro, so that the upper strips are displaced over the lower strips to provide the same interplay between the apertures in the two sets of strips as with the previous embodiment described above. In this case, too, the pinion can be easily provided with a motorized, remotely operated drive.

It will be appreciated that both the upper strips and the lower strips can be readily made from a material and in a thickness such as to make them flexible. If so designed, the strips will also operate within an arched sheet comprising arched tunnels, by easily flexing to accommodate the curvature of their seats.

Depending on the material of the strips and on their manufacturing process, the mutual sliding movement between the upper and the lower strips might sometimes be hampered, among other causes, by the mutual interactions of the edges of the apertures. In such cases, a transparent film may be inserted between each pair of an upper and a lower strips.

Although a twin-wall sheet is mentioned above, the invention can also be incorporated in triple-wall sheets or, more generally, in multiwall sheets with a larger number of walls, by using one of the multiple sets of tunnels there available.

The material of either the upper or the lower strips may be a thin metal leaf such as steel or aluminum, but preferably it is a synthetic material, such as polyethylene. In the latter case, the polyethylene material may be tinted or smoked, if only a partial shading is desired, or may be made totally opaque, e.g. by aluminizing the upper side of the strip so that it completely reflects the incident light.

Although the shape of the apertures in both the upper and the lower strips is rectangular in the embodiment shown on the drawings, the shape of the apertures might also be circular, oval, and in fact any desired shape may be chosen. Also, although the maximum range of shading adjustment is achieved by having the apertures identical in both the upper and the lower strips and by having the apertures spaced by a distance substantially identical to the aperture width, all these dimensions can be chosen differently, if a more restricted range of adjustment is desired.

It should further be pointed out that the driving mechanisms 28-46 and 50-52 as described above and shown on the drawings are only examples of simple and unexpensive driving means, but the same task could be performed by many other known devices for causing a linear displacement, such as crank-and-rod devices, screw devices, and the like. All such mechanisms are regarded as falling within the scope of invention, since they all perform the same function.

Moreover, although it is presently preferred to displace only one of the shading strips, while maintaining the other strip in a fixed position, both strips could be displaced in counter motion, e.g. by providing an oblique slot also in the lower strips, at right angles to the slots of the upper strips, and in engagement with the pins. It is also evident that the sheet assembly of the invention can be easily provided with a motorized drive in lieu of the knob shown in the drawings, by using readily available device.