BRACKET

This invention relates to a bracket for use in the construction of a polytunnel, and in particular to a bracket for use in a polytunnel of the type in which a vent is to be formed at or close to the top of the polytunnel. The invention also relates to a polytunnel structure incorporating such a bracket, the bracket being used in the provision of a vent at or close to the top of the polytunnel structure.

A range of polytunnel designs are known in which a top vent is provided. In such arrangements, warm air within the polytunnel will tend to rise, escaping from the polytunnel by way of the vent formed at or near the top of the polytunnel, relatively cool air being drawn into the polytunnel, for example through the sides or ends thereof, to replace the warm air that has escaped through the vent.

Where polytunnels are used in areas in which relatively heavy rainfalls can be expected then, whilst the provision of a top vent may be desirable to aid cooling of the interior of the polytunnel, an arrangement is required which is able to prevent or restrict rainwater ingress through the vent as the ingress of such rainwater may cause damage to plants or crops within the polytunnel. Simply leaving an open, uncovered vent in the top of the polytunnel is thus not thought to be appropriate. Restricting rainwater ingress is sometimes achieved by providing a section of tunnel cover material supported at a location spaced above the vent. Obviously, this requires structural components to be provided to support the section of cover material.

It is an object of the invention to provide a bracket suitable for use in such an arrangement to allow the formation of a top vent in a relatively simple and convenient manner. Another object of the invention is to provide a polytunnel structure incorporating a vent at or close to the top thereof, the vent being provided using such a bracket. According to the present invention there is provided a polytunnel bracket comprising a first bracket member pivotally attached to a second bracket member, wherein the first and second bracket members each define a passage through which respective polytunnel cover support members can extend, in use.

The first and second bracket members are preferably substantially identical to one another.

The passages provided in the first and second bracket members are conveniently of non-circular cross-sectional shape. By way of example they may be of flat sided oval, or the like, shape.

The first and second bracket members each conveniently have associated therewith respective clamp means whereby the bracket members can be clamped around the respective cover support members. The clamp means may comprise flanges attached to the parts of the bracket members defining the passages. Preferably, threaded fasteners are provided to allow the flanges to be drawn towards one another.

The bracket members may include openings by which they may be bolted to the respective cover support members.

The invention further relates to a polytunnel structure comprising a first cover support member and a second cover support member, the first and second cover support members being secured to one another using a bracket of the type defined hereinbefore, wherein the first cover support member extends through the first bracket member, and an end part of the second cover support member extends through the second bracket member, the bracket securing the first and second cover support members relative to one another such that an end section of the first cover support member overlies, and is spaced apart from, part of the second cover support member.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view illustrating part of a polytunnel structure in accordance with an embodiment of the invention;

Figure 2 is an enlargement of part of the polytunnel structure shown in Figure 1;

Figure 3 is an enlarged view illustrating the bracket used in the part of the polytunnel structure shown in Figure 2; and

Figure 4 is a view illustrating part of the bracket of Figure 3.

As shown in Figure 1, a polytunnel structure 10 comprises a pair of rows of legs 12. Each leg 12 includes, at its upper end, a V- or Y-shaped section 14, the limbs of which are used to support cover supporting members. In a typical polytunnel structure, the cover support members are of arcuate form and extend between a leg of one of the rows and a corresponding leg of the other of the rows. In the structure shown in Figure 1, however, rather than have a single, continuous cover support member extending between respective legs in the two rows, instead the lower ends of respective first cover support members 16 are carried by the legs 12 of one of the rows, and the lower ends of respective second cover support members 18 are carried by the legs 12 of the other of the rows. The upper ends of the first and second cover support members 16, 18 overlap one another and are secured to one another by respective brackets 20. The design of the brackets 20 is such that the end parts of the second cover support members 18 are attached to the first cover support members 16 at locations part way along the length of the first cover support members 16. End sections of the first cover support members 16 thus overlie parts of the second cover support members 18.

Stays 22 are secured to the ends of the first cover support members 16, securing the ends of the first cover support members 16 to the second cover support members 18. A first cover member 26, for example of a flexible plastics material, extends over the first cover support members 16, the first cover member 26 extending from a position adjacent the lower ends of cover support members 16 to a position adjacent the upper ends thereof. A second cover member 28 is carried by the second cover support members 18. The second cover member 28 stops short of the upper ends of the second cover support members 18. In the structure shown, the upper edge of the second cover member 28 lies adjacent the points at which the stays 22 are attached to the second cover support members 18. The cover members 26, 28 define a tunnel, providing rainwater and environmental protection to plants or crops located within the tunnel, a vent 30 being defined between the upper edge of the first cover member 26 and the upper edge of the second cover member 28 through which warm air from within the polytunnel is able to escape therefrom in substantially the manner outlined hereinbefore.

The vent 30 is preferably closed by an insect screen or the like. Such a screen restricts insect access to the interior of the polytunnel whilst maintaining a substantially unimpeded flow of air from within the polytunnel to the exterior thereof.

In the structure illustrated, the first and second cover support members 16, 18 are of a tubular material of non-circular cross-sectional shape. In particular, they are of a tubular material having a cross-sectional shape composed of a pair of generally planar side walls interconnected by part- circular end walls. The cross-sectional shape is thus of flat sided oval-like form. It will be appreciated, however, that this represents merely one example, and that other shapes may be used without departing from the scope of the invention.

The brackets 20 are identical to one another and so only one of the brackets 20 will be described herein in further detail.

As illustrated in Figures 2 and 3, each bracket 20 takes the form of a first bracket member 32 and a second bracket member 34. The bracket members 32, 34 are identical to one another, and Figure 4 illustrates one of the bracket members 32, 34 in isolation. Each bracket member 32, 34 takes the form of a section of steel sheet or a similar material bent to define a passage 36 and a pair of overlapping flanges 38. The passages 36 are of a cross-sectional shape substantially matching the cross-sectional shapes of the first and second cover support members 16, 18. Accordingly, they may be of flat-sided oval-like form. The flanges 38 are provided with aligned openings 40 and with aligned arcuate slots 42. As shown in Figures 2 and 3, the bracket members 32, 34 are arranged such that the flanges 36 thereof are interleaved and the openings 40 thereof are aligned with one another. In this position, a bolt 44 and associated nut 46 are used to secure the bracket members 32, 34 to one another, allowing pivotal movement therebetween. Another nut and bolt 48 extends through the aligned arcuate slots 42 of the brackets 32, 34 and can be used, once tightened, to lock the bracket members 32, 34 against pivotal movement. Further clamping nuts and bolts 50 also extend through the arcuate slots 42 and are able to be used to draw the flanges 38 towards one another. Whilst the use of nuts and bolts is convenient, other fasteners, preferably of threaded form, may be used.

The first cover support member 16 extends completely through the passage 36 defined by the first bracket member 32, the first bracket member 32 being positioned part way along the first cover support member 16. The end part of the second cover support member 18 extends completely through the passage 36 defined by the second bracket members 34, the second bracket member 34 being fitted to the end of the second cover support member 18. With the various nuts and bolts 44, 46, 48, 50 tightened, it will be appreciated that the bracket 20 provides a robust connection between the cover support members 16, 18. If desired, in order to further strengthen the fixing of the bracket 20 to the second cover support member 18, an opening may be drilled in the second cover support member 18 aligned with openings 52 formed in the second bracket member 34, and a nut and bolt 54 used to fasten the bracket 20 to the second cover support member 18. It will be appreciated that such an arrangement substantially prevents movement of the bracket 20 along the length of the second cover support member 18. A similar approach may be taken with the first bracket member 32 and the first cover support member 16, if desired.

It will be appreciated that the use of a non-circular cross-sectional shape material for the cover support members 16, 18 and for the passages 36 results in the orientation of the brackets 32, 34 being fixed, in use. By using a bracket 20 of the type outlined hereinbefore, it will be appreciated that variations in the lengths or radius of curvature of the cover support members 16, 18 or angles of the Y-shaped sections 14 of the legs 12, which may result in the angles at which the cover support members 16, 18 meet one another varying, in use, can readily be accommodated by adjustment of the relative angular orientations of the bracket members 32, 34 of the brackets 20. It is envisaged that, during assembly, the polytunnel structure 10 will initially be constructed with the nuts and bolts 44, 46, 48, 50 left relatively loose, allowing the angle between the bracket members 32, 34 to adjust, and allowing the first bracket member 32 to move along the first cover support member 16 as required. Once the correct positions and orientations have been found, then the nuts and bolts 44, 46, 48, 50 can be tightened to clamp the bracket 20 to the cover support members 16, 18 and to fix bracket members 32, 34 to one another against relative angular movement, after which the cover members 26, 28 may be positioned and anchored in position. The use of the brackets 20 thus provides a relatively simple way of forming a top vent in a polytunnel, accommodating variations that may occur through manufacturing variations or arising from the environment in which the polytunnel is to be erected.

Although the structure shown in Figure 1 is of relatively short length, including only four legs 12 in each row, it will be appreciated that the structure will typically be of significantly greater length than this, often extending over substantially the full length of a field. Furthermore, whilst only two rows of legs 12 are illustrated, typically there will be a greater number of rows, and certain of the rows may support ends of cover support members associated with two adjacent tunnels.

Whilst a specific example embodiment of the invention is described and illustrated herein, it will be appreciated that a wide range of modifications or alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.