GB2062050A - Protective building structures - Google Patents

Abstract

A lightweight protective structure comprises a pair of spaced end supports 1, 2 longitudinal flexible filaments 20 extending between the end supports, means 14, 23 for maintaining the filaments under tension, and a cover 30 of thermoplastics tubular film extending around and supported by the filaments to form a double layer of protective film. Each end support comprises a pair of elongated members diverging from a base, the two end supports being interconnected by a pair of filaments around which hold the tubular film taut. A further filament intermediate and at a different height from those defining the edges of the cover, is provided to hold the film in a ridge or trough configuration. <IMAGE>

Description

SPECIFICATION Protective structure The invention relates to protective structures for covering areas of ground, especially for agricultural uses in the protection of large areas of crops.

According to one aspect of the present invention there is provided a protective structure for covering an area of ground, consisting essentially of a pair of spaced end supports, longitudinal flexible filaments extending between the end supports, means for maintaining the filaments under tension, and a cover of thermoplastics tubular film extending around and supported by the filaments to form a double layer of protective film; each end support comprising a base and a pair of elongated members extending from the base with a pre-determined mutual divergence such that their extended ends are spaced apart in a direction substantially parallel to the end of the covered area, the two extended ends being connected to the extended ends of the opposing end support by a pair of the filaments around which the tubular film is held taut and which thereby define the longitudinal edges of the cover, each end support also having means for supporting a further longitudinal filament intermediate and at a different height from those defining the edges of the cover, the film passing over or under the further longitudinal filament so as to hold the film in a ridge or trough configuration respectively.

The present structures are particularly suitable for covering long strips of ground, for example the whole length of a field. In order to stabilise such elongated structures, intermediate supports for the filaments may also be provided, preferably comprising a base and a pair of extended elongated members substantially as used in the end supports.

Examples of flexible filaments which may be used in appropriate circumstances, include wires, cables, twisted ropes and ropes having parallel filaments encased in thermopiastic sheaths such as those sold under the name 'Parafil'. In preferred structures, the edge-defining longitudinal filaments are maintained substantially parallel to the ground. Similarly filaments parallel to each other are also preferred. It is not, however, essential to have parallel configurations, and drainage of rain water from shorter structures may be assisted for example, by making the edgedefining filaments diverge so that the floor of the trough will slope upwards, assuming that the tubular film is of substantially constant diameter.

In each end support, the means for supporting the intermediate filament preferably comprises a further elongated member extending upwards from the base between the other two members.

The structure may then have either a trough or a ridge configuration depending on the length of the intermediate member. For a trough configuration, an alternative means for supporting the intermediate filament is simply a strop loosely interconnecting the extended ends of the adjacent elongated members, which the intermediate filament being passed over the strop and drawn tight.

Variations in the width of the tubular film may be accommodated and the film rendered taut in a number of ways. For example, where the intermediate filament is supported by a simple strop, the length of the strop may be made adjustable. Similarly, where a further elongated member provides the support for the intermediate filament,-this further member may be adjustable in length. An alternative approach is to mount the elongated members on the base such that their divergence angle is adjustable. End-supports in which the elongated members may be folded together are also more readily stacked for storage.

The use of single intermediate filaments provides the simplest configurations of a single peak or single trough. However, further longitudinal filaments may be provided, e.g. to give two peaks or two troughs as the case may be.

In both such cases, a filament is provided midway between and preferably at the same height as the edge-defining filaments, with higher or lower intermediate filaments respectively, between them.

The means for maintaining the filaments in tension, may suitably comprise an anchorage embedded in the ground in line with but external to the covered area, the elongated members being linked to the anchorage by means of guys attached preferably adjacent to their extended ends. The guys are preferably provided by extending the filaments beyond the end support members sufficiently to reach down to the anchorage, the ends of the elongated members being clamped to the filaments to prevent them sliding therealong.

In one extreme configuration, the angle between the diverging elongated members is 1 800, both members extending from the base along the ground, with one or more intermediate members extending upwards to provide the structure with a peaked configuration, and to hold the film clear of the ground over its full area other than along its longitudinal edges. However, the present invention is particularly useful for providing a light-weight roof held clear of the ground over much larger areas, by combining a plurality of such protective structures, and according to a second aspect of the present invention, a modular roof for covering large areas of ground, comprises a plurality of protective structures as described hereinabove, with the longitudinal edges of adjacent structures held in close proximity with one another.

The individual structures of the modular roof preferably have a troughed configuration in order that rainwater collected over the area of the structure will drain away to the ends. If ridged configurations are used, it is generaily preferable to provide gutters below adjacent pairs of edges in order to catch rainwater seeping through, and thereby enable the moisture content of the underlying ground to be controlled.

The elongated members of each end support diverge from a single base, and are most simply guyed to a single anchorage. Hence unless the outermost members extend outwards along the ground, the configuration is basically unstable and requires lateral support. This can readily be provided in individual structures by lateral guys to further anchorages for example; and in modular roofs, stability may be acquired by the securing together of the adjacent structures.

The invention is illustrated by the following description of specific embodiments thereof shown in the accompanying drawings of which: Figure 1 is a side view of a protective structure having a trough configuration, Figure 2 is a section of the structure shown in Figure 1 taken along the line Il-Il, Figure 3 is a further section through the embodiment shown in Figure 1, taken along the line Ill-Ill, with the features beyond the plane of section omitted, Figures 4 and 5 are sections corresponding to those of Figures 2 and 3 of an alternative structure having a ridge configuration, Figures 6 and 7 are sections corresponding to Figures 2 and 3 of an alternative double-trough structure, and Figure 8 is a sketch of part of a field covered with a modular roof made up of a plurality of protective structures of the kind shown in Figures 1-3.

The protective structure shown in Figures 1-3 consists essentially of a pair of opposed spaced end supports 1,2, three longitudinal flexible filaments 20,21,22 extending between the end supports, guys 23, 24, 25 for maintaining the filaments under tension, and a cover 30 of translucent poiyethylene tubular film supported by the longitudinal filaments. Each end support comprises a base 3 and a pair of elongated members 4, 5 extending upwards from the base while diverging such that their extended ends 6, 7 are spaced apart in a direction substantially parallel to the end of the covered area 8 of the ground above which the structures is erected. The two members extending from the base are welded thereto and are accordingly maintained at a predetermined angle of divergence.The extended ends of each pair of elongated members 6, 7 are connected to the corresponding extended ends 9 of the opposing end support by a pair of parallel filaments 21, 22 which are threaded through the tubular film 30. The film is held tautly around these two filaments which thereby define the edges of the cover. The filaments extend through holes in the ends of the elongated members 4, 5 where they are clamped (by means not shown) before continuing as the guys 24, 25.

The two elongated members are interconnected by a strop 11 secured near their extended ends. The middle of the strop is attached to the base by a tie 12, both the strop and the tie being taut. Over the top of the join between the strop and the tie is a saddle 1 3 on which rides the lower longitudinal filament 20. This lower filament then continues as the guy 23. All three guys 23, 24, 25 are attached to a single anchor 14. The lower filament 20 is not threaded through the tubular film like the two upper filaments 21 and 22, but instead rests on top of the film and holds it down in a trough configuration.

Also shown in Figure 1 is an intermediate support 31 which is substantially the same as the end supports and has a base 32 from which extends two elongated members 33 interconnected by a strop (not shown) with a saddle for supporting the intermediate filament The extended ends are provided with a slot into which the corresponding outer filament may be inserted and locked. The thermoplastic film enveloping the filament may be inserted into the slot together with the filament, but it is preferred generally to cut this away 34 and provide reinforcement at that point to avoid premature failure due to localised stresses.

In the embodiment shown in Figures 4 and 5, the end support comprises a base 41 from which extend upwards three elongated members of approximately equal length, all three members lying in the same plane with the central member 42 being substantially upright while the other two members 43, 44 are inclined symmetrically on ejther side. All three filaments 45, 46, 47 pass through holes in the extended ends of the three members, each hole having means (not shown) for clamping them. As before the two outer filaments pass through the tubular film and thereby define the edges of the cover, while in this embodiment the intermediate filament 45 extends underneath the tubular film and supports it in a ridge configuration.

It is not essential that each module has a single ridge or trough, and in Figures 6 and 7 there is provided an example of a double-trough structure.

This utilises an end support similar to that shown in Figures 4 and 5 except that the elongated members 51, 52, 53 all extend to substantially the same height above the ground. Each pair of members is provided with a strop 54, 55, tie 56, 57 and saddle 58, 59 for supporting an intermediate filament 60, 61 in a manner similar to that shown in Figure 2, the tubular film 62 passing under the intermediate filaments 60, 61 over the central filament 63 and around the edgedefining filaments 64, 65.

Figure 8 shows pictorially how a number of the structures shown in Figures 1-3 may be placed side by side to form a modular roof for covering large areas. The whole structure is preferably stabilised by clipping together the extended ends of adjacent end supports. For covering crops, translucent or transparent film is preferred, and indeed the present invention provides a structure which can be lighter, cheaper and more easily erected over larger areas than traditional greenhouses. It is also versatile in that opaque or light transmitting film may be selected as appropriate. The edges of the combined structure may be left open, but the protection afforded by the roof may be enhanced by providing walls along the edges, formed for example from the same tubular film passed around just two parallel filaments, one such filament lying along the ground, to give a flat panel as shown in Figure 8.

Claims (10)

1. A protective structure for covering an area of ground, consisting essentially of a pair of spaced end supports, longitudinal flexible filaments extending between the end supports, means for maintaining the filaments under tension, and a cover of thermoplastics tubular film extending around and supported by the filaments to form a double layer of protective film, each end support comprising a base and a pair of elongated members extending from the base with a predetermined mutual divergence such that their extended ends are spaced apart in a direction substantially parallel to the end of the covered area, the two extended ends being connected to the extended ends of the opposing end support by a pair of the filaments around which the tubular film is held taut and which thereby define the longitudinal edges of the cover, each end support also having means for supporting a further longitudinal filament intermediate and at a different height from those defining the edges of the cover, the film passing over or under the further longitudinal filament so as to hold the film in a ridge or trough configuration respectively.

2. A protective structure according to claim 1 wherein the means for supporting the further longitudinal filament comprises a further elongated member extending upwardly from the base between the two diverging elongated members of an end support.

3. A protective structure according to claim 1 wherein the means for supporting the further longitudinal filament comprises a strop interconnecting the extended ends of adjacent elongated members of an end support.

4. A protective structure according to any one of the preceding claims wherein the diverging elongated members of an end support are so mounted on the base that the divergence angle therebetween is adjustable.

5. A protective structure according to any one of the preceding claims wherein the angle between the diverging elongated members of an end support is 1800.

6. A protective structure according to any one of the preceding claims comprising a plurality of intermediate longitudinal filaments arranged to hold the film in a multiple ridge or trough configuration.

7. A protective structure according to any one of the preceding claims including a plurality of lateral supporting guys.

8. A protective structure according to any one of the preceding claims wherein the film is a polyethylene film.

9. A modular roof comprising a plurality of protective structures according to any one of the preceding claims, the longitudinal edges of adjacent protective structures being held in close proximity to each other.

10. A protective structure constructed and arranged substantially as herein described and with reference to any one of the drawings.