GB2540411A

GB2540411A - Polytunnel structure with a vent drive arrangement

Info

Publication number: GB2540411A
Application number: GB1512466.2A
Authority: GB
Inventors: Whatton Rolly
Original assignee: Haygrove Ltd
Current assignee: Haygrove Ltd
Priority date: 2015-07-16
Filing date: 2015-07-16
Publication date: 2017-01-18
Also published as: GB201512466D0; WO2017009627A1

Abstract

A polytunnel structure with a support structure including hoop members 14 carrying a cover 16 defining a barrel roof tunnel profile 20, and a drive arrangement for a vent flap formed by or in the cover 16 comprising a gearbox 32 located outside of the tunnel profile 20 having an input and an output, the output being connected to a vent drive mechanism and the input being connected to a drive input means 44 located within the tunnel profile 20. The drive input means 44 may connect to the input via a drive shaft 40 which extends through a mesh screen. There may be a gearbox mounting bracket 38 securable to one of the hoop members, and this may comprise inner and outer components, with a mesh screen extending between these components. The drive input means may comprise a chain driven pulley, a hand crank, or a motor.

Description

POLYTUNNEL STRUCTURE WITH A VENT DRIVE ARRANGEMENT

This invention relates to a polytunnel structure and vent drive arrangement, and in particular to a polytunnel structure including a drive arrangement operable to drive the vent of a polytunnel structure or the like between open and closed positions, whilst enabling the provision of an insect screen. A typical design of polytunnel structure comprises a series of upright legs arranged in rows that are spaced apart from one another. Cover supporting hoop members are carried by the legs, each hoop member being supported, at one end, by a leg located in one of the rows, and at its opposite end by a leg located in an adjacent row. A cover, for example of polythene or another suitable flexible plastics material is supported by the hoop members. Anchoring ropes or tapes extend over the cover and are anchored, for example, to the legs, to secure the cover in position. A number of polytunnel structures of the type outlined hereinbefore may be arranged side-by-side. When arranged in this fashion, the row of legs located adjacent the edges of two adjacent ones of the structures may serve to carry the hoop members of both of the structures, thereby avoiding the unnecessary duplication of components. Where polytunnel structures are arranged in this manner, ventilation of the interior of the structures may be undesirably restricted as air flow into and from the structures may occur substantially only at the open ends of the tunnels and along the sides of the outermost two of the structures. In order to enhance ventilation in such circumstances, it is known to provide vent flaps in the covers of one or more of the polytunnel structures, and a drive arrangement allowing rolling up of the vent flaps.

One disadvantage of providing vent flaps is that, when open, the vent flaps may allow insects to enter the polytunnel structure, and the insects may cause damage to, for example, crops growing within the polytunnel structure. Clearly, this is undesirable. In order to obviate this problem, it is known to provide a mesh material screen that extends across the opening formed when the vent flap is rolled up, the mesh material screen being located to the inside of the polytunnel relative to the location of the vent flap. Whilst the provision of a mesh material screen may serve to prevent the ingress of insects, the presence of the screen may hamper the operation of the drive arrangement used to roll up or unroll the vent flap material, in use. Known solutions to this problem are to locate the drive arrangement to the outside of the polytunnel structure. However, such location has the disadvantage that gaining access to the drive arrangement in order to adjust the level of ventilation is impeded. Another approach is to form a slit or large opening in the material of the mesh screen through which translating parts of the drive arrangement can extend to allow operation of the drive arrangement from the interior of the structure whilst still being able to drive parts of the drive arrangement located to the exterior of the mesh material screen for movement. However, the formation of a large slit or opening in the mesh material screen may result in insects still being able to enter the structure, and so carries the risk of insect damage to the crops being cultivated in the structure.

It is an object of the invention to provide a polytunnel structure with a vent drive arrangement in which at least some of the disadvantages associated with known arrangements are overcome or are of reduced effect.

According to the present invention there is provided a polytunnel structure comprising a support structure including a series of hoop members carrying a cover, the hoop members defining a barrel roof tunnel profile, and a drive arrangement for a vent flap formed by or in the cover, the drive arrangement comprising a gearbox located outside of the tunnel profile, the gearbox having an input and an output, the output being operably connected to a vent drive mechanism and the input being connected to a drive input means located within the tunnel profile.

The drive input means and the input to the gearbox are conveniently interconnected by an input drive shaft that extends through a mesh material screen. A gearbox mounting bracket is conveniently provided, the gearbox mounting bracket being securable to one of the hoop members and operable to support the gearbox to the outside of the tunnel profile. The bracket is preferably of a form comprising an inner component located, in use, within the tunnel profile and an outer component located, in use, externally of the tunnel profile. The mesh material screen may be located between the inner and outer components of the bracket.

The vent drive mechanism preferably comprises a rotatable and translatable bar onto and from which vent flap material may be wound or unwound, in use, and a telescopic drive shaft, the telescopic drive shaft being connected to the output of the gearbox and to the bar by respective universal or flexible drive transmission couplings.

An arrangement of this type is advantageous in that the vent may be operated from within the tunnel structure, thereby enabling adjustment of the degree of ventilation in a relatively convenient manner, whilst the integrity of the mesh screen is maintained by requiring only a small hole to be provided therein through which the input drive shaft extends. As no translatable components need to extend through the opening in the mesh screen, the dimensions of the hole or opening provided in the mesh screen are restricted, and so the risk of ingress of insects past the mesh material screen is minimised.

The drive input means may comprise, for example, a chain driven pulley. Alternatively, it may comprise, for example, a hand driven crank or a motor drive arrangement, for example an electrically operated motor drive arrangement. One option may be for the drive input means to comprise a connection whereby the output of an electrically driven motor may be temporarily connected to drive the input drive shaft for rotation.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

Figures la to lc are diagrammatic views illustrating a polytunnel structure in accordance with an embodiment of the invention;

Figure 2 is a view illustrating part of the structure of Figure 1; and

Figure 3 is a view illustrating components of the structure of Figure 1 in greater detail.

Referring to the accompanying drawings, a polytunnel structure 10 is illustrated that comprises a series of upstanding legs 12 arranged in rows, Figure 1 illustrating legs 12 located in two adjacent rows. The upper end of each leg 12 is of forked or bifurcated form. Cover support hoop members 14 are supported at their ends by the forked parts of respective ones of the legs 12, each hoop member 14 interconnecting a leg 12 located in one of the rows and a corresponding leg 12 located in an adjacent one of the rows. A flexible, plastics material cover 16 is supported by the hoop members 14, the cover 16 being secured or anchored in position by anchoring ropes or tapes 18. The hoops 14 together define a barrel roof tunnel profile 20. Depending upon the application in which the polytunnel structure is to be used, several such structures may be provided in a side-by-side fashion in the conventional manner.

The cover material 16, adjacent the ends of the structure, may extend over the full extent of the hoop members 14. However, elsewhere, the cover material may be of shorter extent, defining a ventilation opening. Secured to the hoop members 14 and extending lengthways of the tunnel structure are a pair of mesh screen fixing bars 22 to which a mesh screen material 24 is secured, the mesh screen material extending over substantially the entire length of the structure, and extending from a position just above the uppermost ends of the legs 12 and around, in the arrangement shown, approximately one quarter of the length of each of the hoop members 14, to cover the ventilation opening. It will be appreciated that the size of the ventilation opening, and hence the dimensions of the mesh screen material 24 will depend upon the intended application in which the structure is to be employed and the desired maximum level of ventilation, and the invention is not restricted in this regard.

The polytunnel structure 10 further includes a section of vent flap material 26. In some applications, this material may take the form of an integral extension of the cover material 16, but it may alternatively comprise a separate integer that, for example, secured to the cover material 16. The vent flap material 26 is of dimensions sufficiently large to allow the vent flap material 26 to overlie and substantially close the ventilation opening, when desired. A bar 28 is secured to the lower edge of the vent flap material 26 and is arranged such that rotation of the bar 28 results in the vent flap material 26 being wound onto, or unwound from, the bar 28, depending upon the direction of rotary motion of the bar 28, and that the rotation of the bar will be accompanied by translational movement thereof along the tunnel profile 20, the bar 28 being supported upon the hoop members 14.

The bar 28 forms part of a vent drive mechanism that further comprises a telescopic drive shaft 30 and a gearbox 32. The telescopic drive shaft 30 is coupled, at one end thereof, to the bar 28 by way of a universal or flexible drive coupling, 34, and at the other end thereof to the gearbox 32 by another universal or flexible drive coupling 36. The gearbox 32 is mounted upon a bracket 38 secured to one of the hoop members 14, the bracket 38 supporting the gearbox 32 in a position to the outside of the tunnel profile 20. In this arrangement, the gearbox 32, telescopic drive shaft 30 and couplings 34, 36 are all located outside of the cover material 16 and the mesh screen material 24, externally of the profile 20 of the tunnel. The nature of the bracket 38 is such that it is of two part form, with one part 38a located internally of the tunnel profile 20, the other part 38b being located externally of the tunnel profile 20, the two parts 38a, 38b being bolted to one another and clamping the bracket 38 to the associated hoop member 14. The material of the mesh screen is located between the parts 38a, 38b of the bracket 38.

The gearbox 32 includes an input 32a and an output 32b. The coupling 36 is connected to the output 32b. To the input 32a is connected an input drive shaft 40 which extends through the cover 16 and mesh material screen 24 to a position located within the tunnel profile 20. As shown in Figures 2 and 3, a support 42 may be provided, secured to the adjacent hoop members 14, to provide support to the drive shaft 40.

To the end of the drive shaft 40 remote from the gearbox 32 is mounted, in this embodiment, a pulley 44 with which a chain 46 is entrained.

In use, an operator may pull on one or other runs of the chain 46 to drive the pulley 44, and hence the drive shaft 40 for rotation, the applied load being reacted via the support 42 to the structure 10. The rotation of the drive shaft 40 drives the gearbox 32, and hence the telescopic drive shaft 30 for rotation, which in turn causes rotation of the bar 28. Depending upon the direction of rotation, the vent flap material 26 will either be wound onto or unwound from the bar 28, increasing or decreasing the level of ventilation. The rotation of the bar 28 will be accompanied by translational movement thereof. As this movement results in a change in the distance of the end of the bar 28 from the gearbox 32, the telescopic drive shaft 30 will undergo a change in length to accommodate this movement.

It will be appreciated that as only the drive shaft 40 needs to extend through the mesh screen material 24, and that the drive shaft 40 simply rotates, not undergoing any translational movement, the opening in the mesh screen material 24 through which the drive shaft 40 extends need only be small, just large enough to allow the drive shaft 40 to pass therethrough. Accordingly, the risk of insects being able to enter the structure 10 is low.

Whilst in the embodiment described hereinbefore a chain drive arrangement is used to drive the drive shaft 40 for rotation, other forms of drive input means may be used. By way of example, the pulley 44 could be replaced by a hand crank mechanism. Alternatively, the drive input means could take the form of an arrangement whereby an electrically operated motor could be temporarily connected to the drive shaft 40 to apply a torque to the drive shaft 40.

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

Claims

CLAIMS:

1. A polytunnel structure comprising a support structure including a series of hoop members carrying a cover, the hoop members defining a barrel roof tunnel profile, and a drive arrangement for a vent flap formed by or in the cover, the drive arrangement comprising a gearbox located outside of the tunnel profile, the gearbox having an input and an output, the output being operably connected to a vent drive mechanism and the input being connected to a drive input means located within the tunnel profile.

2. A structure according to Claim 1, wherein the drive input means and the input to the gearbox are interconnected by an input drive shaft that extends through a mesh material screen.

3. A structure according to Claim 1 or Claim 2, wherein a gearbox mounting bracket is provided, the gearbox mounting bracket being securable to one of the hoop members and operable to support the gearbox to the outside of the tunnel profile.

4. A structure according to Claim 3, wherein the bracket is of a form comprising an inner component located, in use, within the tunnel profile and an outer component located, in use, externally of the tunnel profile.

5. A structure according to Claim 4, wherein where a mesh material screen is provided, the mesh material screen extends between the inner and outer components of the bracket.

6. A structure according to any of the preceding claims, wherein the vent drive mechanism comprises a rotatable and translatable bar onto and from which vent flap material is wound or unwound, in use, and a telescopic drive shaft, the telescopic drive shaft being connected to the output of the gearbox and to the bar by respective universal or flexible drive transmission couplings.

7. A structure according to any of the preceding claims, wherein the drive input means comprises a chain driven pulley.

8. A structure according to any of Claims 1 to 6, wherein the drive input means comprises a hand driven crank.

9. A structure according to any of Claims 1 to 6, wherein the drive input means comprises a motor drive arrangement.

10. A structure according to Claim 9, wherein the motor drive arrangement comprises an electrically operated motor and a drive connection whereby the output of an electrically operated motor can be temporarily connected to drive the input drive shaft for rotation.