WO2017153711A1

WO2017153711A1 - Tunnel arrangement

Info

Publication number: WO2017153711A1
Application number: PCT/GB2017/050439
Authority: WO
Inventors: Rolly WHATTON
Original assignee: Haygrove Limited
Priority date: 2016-03-08
Filing date: 2017-02-21
Publication date: 2017-09-14
Also published as: GB2549577A; GB201603960D0; GB201702796D0

Abstract

A tunnel arrangement comprising a plurality of cover support members (16) and a cover (18) supported by the cover support members (16), the cover support members (16) together defining a tunnel profile (20), wherein the tunnel arrangement further comprising a vent arrangement with at least one of the vent regions being located at a height above that of a support cable (28) and at least another of the vent regions being located lower than a height of the support cable (28).

Description

TUNNEL ARRANGEMENT

This invention relates to a tunnel arrangement, for example of the type comprising rows of legs interconnected by cover support members upon which a cover is supported. Such arrangements are commonly used in agricultural settings, for example to provide protection for crops, to extend the growing season thereof, or to allow the growing conditions to be enhanced or optimised, thereby enhancing or maximising crop yield. Whilst the invention may be applied to a single, stand-alone tunnel arrangement, it is also applicable to field scale arrangements in which a number of tunnel arrangements are provided side-by-side to cover a relatively large area.

In a typical tunnel arrangement, the cover support members are of arcuate form, together defining a part cylindrical or barrel roof type profile. Whilst such a shape may be advantageous in that the tunnel arrangement is of reasonably good strength, and so is able to withstand side winds and the like, one disadvantage with such an arrangement is that where it is desired to provide vents to allow increased ventilation of the interior of the tunnel arrangement, venting is often restricted.

Typically, venting is achieved by providing within the cover, vent flaps, and providing an arrangement whereby the vent flaps can be rolled up to increase the level of ventilation. The vent flaps may comprise parts or sections of the cover. By way of example, the lower edges of the vent flaps may be secured to a rotatable and translatable shaft, rotation of which rolls up the vent flap, the shaft translating or moving so as to follow the tunnel profile during such rotation. It has been found that where used with barrel roof profile tunnels, rolling up or unrolling of the vent flap material at or close to the uppermost part of the tunnel is impeded. Primarily, this is because near the generally horizontally extending uppermost part of the tunnel arrangement the ropes, straps or the like used to anchor the cover in position and beneath which the shaft must move, in use, tightly engage the cover and so provide a significant resistance to movement. When the shaft is being rotated to unroll the vent flap material to close the vent region, it has been found that the shaft tends to rotate without undergoing translational movement, resulting in the vent flap material just being loosely unfurled around the shaft, but in the vent region remaining open. Further from the apex, the ropes, straps or the like less firmly engage the cover and so the resistance to movement of a shaft located between the ropes and the cover is reduced. As a consequence, the likelihood of the shaft rotating without undergoing translational movement is reduced. Furthermore, away from the apex where the profile is more steeply sloped, gravity assists in ensuring that such translational movement occurs. The effect of this is that, typically, vent regions are not formed near the apex, leading to the maximum area of the tunnel profile which can be opened to allow venting being in the region of 80% of the total area.

It is an object of the invention to provide a tunnel arrangement in which at least some of the disadvantages associated with known tunnels are overcome or are of reduced effect.

According to the present invention there is provided a tunnel arrangement comprising a plurality of cover support members and a cover supported by the cover support members, the cover support members together defining a tunnel profile, wherein the tunnel profile is of peaked form.

By way of example, the tunnel profile may include a first sloping side and a second sloping side interconnected at the uppermost part of the tunnel profile. The first and second sloping sides may be of substantially flat, planar form. Alternatively, they may be of arcuate form.

The tunnel arrangement may further comprise a vent arrangement whereby vent regions formed in the cover may be opened or closed to vary the degree of ventilation of the tunnel arrangement. At least one of the vent regions may be located at or adjacent the uppermost part of the tunnel profile. The vent arrangement may comprise a rotatable and translatable shaft, rotation and translation of which along the tunnel profile opens or closes the vent regions. It will be appreciated that providing a tunnel profile of the peaked form outlined hereinbefore, the width of the uppermost part of the tunnel arrangement in which venting is not possible or is difficult to achieve is reduced. Accordingly, a greater area, approaching 100%, is available for venting.

Preferably, support cables are provided, each support cable engaging a corresponding cover support member to resist flexing of the cover support member.

The cover support members may be supported upon ground engaging legs. Each leg may be of bifurcated form, supporting cover support members associated with two adjacent tunnel arrangements. In such an arrangement, the support cables may interconnect the cover support members of adjacent tunnel arrangements.

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 a tunnel arrangement in accordance with an embodiment of the invention; and

Figure 2 is a view similar to Figure 1 illustrating alternative embodiments.

Referring Firstly to Figure 1, a tunnel arrangement 10 is illustrated comprising a first row of legs 12 and a second row of legs 14, each leg 12, 14 taking the form of an upright that is screwed into the ground upon which the tunnel arrangement 10 is located, or is otherwise secured in position in an upstanding condition, the rows of legs 12, 14 extending substantially parallel to one another. Each leg 12 of the first row is interconnected with a corresponding leg 14 of the adjacent second row by a respective cover support member 16. A cover 18 of a suitable flexible plastics material is supported by the cover support members 16. Ropes, straps or the like (not shown) extend over the cover 18 and are anchored to the ground or to the legs 12, 14 to secure the cover 18 in position.

The cover support members 16 together define a tunnel profile 20. The cover support members 16 are shaped in such a manner that the tunnel profile 20 defined thereby includes a first sloping side 20a and a second sloping side 20b, the sloping sides 20a, 20b being of generally planar form and being interconnected with one another at a peak or apex 22 at the uppermost part of the tunnel arrangement 10.

Vent regions are formed in the cover 18, vent flaps (forming part of the cover 18) being provided to allow the vent regions to be opened or closed. An edge of each vent flap is secured to a respective rotatable and translatable shaft 24 arranged such that rotation of the shaft 24 results in the vent flap being rolled up onto or unrolled from the shaft 24 (depending upon the direction of rotation) to open or close the associated vent region. In the arrangement shown in Figure 1, each side 20a, 20b includes a pair of vent regions, the tunnel arrangement 10 thus having four vent regions. It will be appreciated, however, that the invention is not restricted in this regard.

In use, as the tunnel profile 20 is defined by two relatively steeply sloping sides 20a, 20b, interconnected at the peak or apex 22, it will be appreciated that the width of the area of the tunnel profile over which the ropes, straps or the like used to secure the cover 18 in position secure the cover sufficiently tightly that they substantially prevent translational movement of the shaft 24, and so prevent or restrict venting is minimised. Throughout substantially all of the shaft movement, the shaft 24 is located upon a relatively steeply sloping part of the profile 20, and so the gravitational forces experienced by the shaft 24 will tend to aid downward movement of the shaft 24 along the profile 20, ensuring that the vent flap material remains relatively tightly wound upon the shaft 24, and that during closing of the vent flap regions, the rotation of the shaft 24 is always accompanied by corresponding translational movement around the tunnel profile 20. Substantially complete venting of the tunnel arrangement may thus be achieved without running an unacceptably high risk of rotation of the shaft not being accompanied by translational or sideways movement of the shaft around the tunnel profile.

As shown in Figure 1, conveniently wind break structures 26 are provided to either side of the tunnel arrangement 10, support cables 28 interconnecting the wind break structures 26. The support cables 28 are located at a height above the tops of the leg 12, 14 but below the apex 22, and are positioned so as to engage with respective ones of the cover support members 16. Clamps, clips or the like are used to secure the cables 28 to the cover support members 16 at each point of engagement therebetween. It will be appreciated that the cables 28 serve to resist or restrict deflection of cover support members 16, resisting deformation of the tunnel arrangement 10 due to winds or the like.

As the cables 28 are located at a significant height above the ground, it will be appreciated that access to the interior of the tunnel, and along the length of the interior of the tunnel, is not restricted. Tractors or other vehicles may thus be used within the tunnel if desired. If the cables were located at a lower height then not only may the ability of the cables to withstand deflection of the profile be reduced, but also vehicular access to parts of the tunnel may be impaired.

Whilst Figure 1 illustrates the support cables 28 as extending between wind break structures 26, it will be appreciated that this need not be the case and the support cables 28 could alternatively extend between other support structures or, indeed, may be anchored to the ground.

The cables 28 are conveniently located at a height relative to the vent flaps and the shafts 24 such that at least one of the vent flaps is located above the height of the cables 28 and another of the vent flaps is located at a height beneath that of the cables 28. The presence of the cables 28 does not, therefore, significantly reduce the ability to fully ventilate the tunnel. Figure 1 illustrates an additional tunnel structure 10a located adjacent the tunnel structure 10 in a side-by-side configuration. The legs 14 are used to support both the cover support members 16 of the tunnel structure 10 and ends of the corresponding cover support members of the structure 10a. The support cables 28 are connected to the cover support members of both structures 10, 10a. In the arrangement illustrated, the additional structure 10a includes just two, larger vent regions instead of the four regions of the structure 10, but requires disconnection of the support cables 28 to allow the full movement of the shafts 24. However, arrangements in which there a four (or more) vent regions as in the structure 10 may be used.

The arrangement described hereinbefore is advantageous in that substantially the entire area of the tunnel structure can be vented, maximising ventilation when required. In contrast, in a typical polytunnel structure only about 80% of the surface of the tunnel can be vented.

Additionally, compared to a barrel roof profile structure, the lengths of the materials used in the cover support members is reduced, thereby allowing materials savings to be made, and also reducing the overall weight of the structure. Additionally, the cover itself is of reduced dimensions. Another benefit is that snow or rain shedding from the cover, in use, is improved. Accordingly, the risk of damage arising from the weight of snow resting upon the cover or the like is reduced. These benefits are achieved without significantly reducing the ability of the arrangement to withstand wind loadings by virtue of the presence of the support cables 28 resisting deflection of the sides 20a, 20b.

Figure 2 illustrates a couple of variants to the arrangement shown in Figure 1. The left hand side of Figure 2 illustrates a tunnel arrangement in which the sides 20a, 20b rather than being of substantially planar form, are of bowed or arcuate form. The sides 20a, 20b are still of relatively steeply sloped form and so the above described benefits of enhanced venting, improved snow shedding and the like are still maintained. Whilst the cover support members contain more material than in the arrangement of Figure 1, savings are still possible compared to a traditional polytunnel structure. The right hand side of Figure 2 illustrates an arrangement similar to that of Figure 1 but in which the apex 22 is less tightly curved. Whilst potentially this may slightly restrict the area of the structure that can be vented, the manufacture of cover support members of this form in which a larger radius curve is formed at the apex is thought to be less complex than the manufacture of cover support members for use in the structure of Figure 1.

The arrangements of Figure 2 still benefit from many of the advantages associated with the arrangement of Figure 1.

Whilst specific embodiments of the invention are described hereinbefore, it will be appreciated that a wide range of modifications and alterations may be made to the arrangements described and illustrated without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS:

1. A tunnel arrangement comprising a plurality of cover support members and a cover supported by the cover support members, the cover support members together defining a tunnel profile, the tunnel profile being of peaked form, a support cable being provided, the support cable engaging a cover support member to resist flexing of the cover support member, the tunnel arrangement further comprising a vent arrangement whereby vent regions formed in the cover may be opened or closed to vary the degree of ventilation of the tunnel arrangement, at least one of the vent regions being located at a height above that of the support cable and at least another of the vent regions being located lower than a height of the support cable.

2. An arrangement according to Claim 1, wherein the tunnel profile includes a first sloping side and a second sloping side interconnected at the uppermost part of the tunnel profile.

3. An arrangement according to Claim 2, wherein the first and second sloping sides are of substantially flat, planar form.

4. An arrangement according to Claim 2, wherein the first and second sloping sides are of arcuate form.

5. An arrangement according to any of Claims 2 to 4, wherein a gentle curve is formed at the interconnection between the first and second sides.

6. An arrangement according to any of the preceding claims, wherein at least one of the vent regions is located at or adjacent the uppermost part of the tunnel profile.

7. An arrangement according to any of the preceding claims, wherein the vent arrangement includes a rotatable and laterally movable shaft located, throughout its range of movement, upon a relatively steeply sloped part of the tunnel profile.

8. An arrangement according to any of the preceding claims, wherein the support cable extends between support structures.

9. An arrangement according to Claim 8, wherein the support structures comprise wind break structures.

10. An arrangement according to any of the preceding claims, wherein a plurality of support cables are provided, each support cable being associated with a respective one of the cover support members.

11. An arrangement according to any of the preceding claims, wherein the support cable is attached to the associated cover support member at two spaced locations on opposite sides of a centreline of the arrangement.