GB2518628A

GB2518628A - Drive arrangement

Info

Publication number: GB2518628A
Application number: GB1317062.6A
Authority: GB
Inventors: Rolly Whatton
Original assignee: Haygrove Ltd
Current assignee: Haygrove Ltd
Priority date: 2013-09-26
Filing date: 2013-09-26
Publication date: 2015-04-01
Also published as: GB201317062D0

Abstract

A drive arrangement comprises a support arm 26 pivotally mounted to a support structure 18, a drive mechanism 24 mounted upon the support arm 26 at a fixed position along the length thereof, the drive mechanism 24 having a drive output, and an output shaft 30 connected to the drive output by way of a universal joint 28. Preferably the arrangement is used for opening vents on polytunnels or greenhouses wherein the support structure carries a flap of flexible material and a roller tube is connected to a free end of the flap and the drive arrangement is operable to drive the roller tube for rotation

Description

DRIVE ARRANGEMENT

This invention relates to a drive arrangement, and in particular to a drive arrangement suitable for supporting at least part of the drive mechanism for, for example, a vent or other movable component of a polytunnel, greenhouse, tent or other building or structure.

It is commonplace to use polytunnels or the like to provide protection to crops to allow cultivation of crops at times of year and in locations in which it would not normally be possible to cultivate a particular crop. As, in some environmental conditions, the temperature or humidity within a polytunnel may exceed the optimum conditions for the cultivation of a particular crop, it is known to provide polytunnels with adjustable vents which can be opened or closed to increase or decrease the level of ventilation of the polytunnel. One simple form of vent in common usage takes the form of a roller tube attached to one end of a flap of polytunnel material, the roller tube being rotatable such that rotation of the roller tube results in the flap of material being wound onto the roller tube. The end of the flap not secured to the roller tube is firmly secured to the polytunnel structure and so remains in a fixed position. It will be appreciated that as the vent is opened or closed, the roller tube translates or moves, working its way towards the fixed end of the flap.

It is desirable to be able to automate the moving of the vents between their open and closed positions. In an arrangement of the type outlined hereinbefore, this may be achieved by providing a motor, for example an appropriately controlled electrically powered motor, to drive the roller shaft for rotation. If the output of the motor or a gearbox associated therewith is directly secured to the roller shaft, then it will be appreciated that the motor and/or gearbox must be mounted in such a manner as to translate with the roller shaft, for example by having the motor and/or gearbox supported upon a guide tube. Such an arrangement is relatively complex. Furthermore, if the vent extends to the position of a gutter between the polytunnel and an adjacent polytunnel, as will often by the case, then in order to accommodate the motor and/or gearbox when the vent occupies its closed position, it is usually necessary to form an opening or notch in the gutter, shaped, sized and positioned to allow the motor and/or gearbox to move to the position it is required to adopt when the vent is closed. The formation of such an opening or notch may impair the performance of the gutter, causing leakage therefrom of rainwater which may then enter the polytunnel potentially causing damage to crops in the vicinity of the leak.

In an alternative arrangement, the motor and gearbox may be mounted to the polytunnel structure in a fixed location, the output of the motor and/or gearbox being connected to the rollel shaft by way of a telescopic drive coupling. Whilst such an arrangement may avoid the need to form an opening or notch in the gutter, it is of increased cost and complexity as telescopic drive couplings are relatively complex.

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

According to the present invention there is provided a drive arrangement comprising a support arm pivotally mounted to a support structure, a drive mechanism mounted upon the support arm at a fixed position along the length thereof, the drive mechanism having a drive output, and an output shaft connected to the drive output by way of a universal joint.

Where such an arrangement is used in driving a roller tube of, for example, a polytunnel vent, for rotation, the free end of the output shaft is connected to the roller tube by way of a further universal joint. In use, operation of the drive mechanism to drive the output shaft for rotation results in rotation of the roller tube. As outlined hereinbefore, this causes displacement or translation of the roller tube which is accommodated by the universal joints. As the roller tube is displaced, the support arm pivots about its pivotal connection to the support structure.

Preferably, the support arm is supported for pivotal movement in a fixed plane. Preferably, the said fixed plane is substantially parallel to the vent when the vent occupies its closed position.

The drive mechanism conveniently comprises a motor, for example an electrically powered motor. It may further comprise a gearbox. However, manually operated arrangements are also envisaged in which case the drive mechanism may comprise a gearbox with an appropriate manual drive input.

The invention further relates to a polytunnel structure comprising a support structure carrying a vent flap of a flexible material, a roller tube connected to a free end of the vent flap, and a drive arrangement operable to drive the roller tube for rotation, the drive arrangement being of the type described hereinbefore.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 to 3 are diagrammatic views illustrating a drive arrangement in accordance with an embodiment of the invention in use in controlling the position occupied by a vent; and Figure 4 is a photograph illustrating a drive arrangement in accordance with an embodiment of the invention.

Referring firstly to Figures 1 to 3, a polytunnel 10 is illustrated diagrammatically. The polytunnel comprises two rows of legs 12 arranged such that each leg 12 of one rows is substantially aligned with a corresponding leg 12 of another row. Support hoops 14 of arcuate fomi interconnect each pail of legs 12 and carry a cover 16, for example of a suitable flexible plastics material. As illustrated, a beam 18 extends lengthwise of the polytunnel, interconnecting the hoops 14, serving to enhance the rigidity of the overall structure. The legs 12, hoops 14 and beam 18 together form a substantially rigid support structure for the polytunnel.

A gutter 19 is carried by the legs 12, serving to conduct rainwater which drains from the cover 16, in use, to an end of the polytunnel. The legs 12 may be designed to additionally support hoops associated with an adjacent polytunnel (not shown) in which case the gutter ig may further serve to collect rainwater draining from the cover 16 of the adjacent polytunnel.

A part of the cover 16 defines a vent flap 20 which is movable between a closed position (see Figure 1) and a fully open position (see Figure 3) to vary the level of ventilation to the interior of the polytunnel. The vent flap 20 may form an integral part of the cover 16, or may comprise a separate piece of material which may be connected to the remainder of the cover 16, or alternatively may be secured to a part of the support structure of the polytunnel, for example by being secured to the beam 18.

A lower, free end of the vent flap 20 is secured to an elongate roller tube 22. It will be appreciated that rotation of the roller tube 22 causes the vent flap 20 to become wound thereon, the roller tube translating or displacing as it is rotated to open or close a vent opening in the polytunnel. During the translation or displacement of the roller tube 22, it will be appreciated that the roller tube 22 is supported by the adjacent hoops 14, and so the path of movement followed by the roller tube 22 will substantially conform with the shape of the hoops 14.

In accordance with this embodiment of the invention a drive arrangement is provided to drive the roller tube 22 for rotation as described below.

In the arrangement illustrated in Figures ito 3 the roller tube 22 is arranged to be driven for rotation by an electrically powered drive mechanism 24 comprising an appropriate motor and associated gearbox. The drive mechanism 24 is mounted upon and carried by a mounting arrangement comprising a support arm 26 which is pivotally mounted at its upper end to a part of the polytunnel structure, for example to the beam 18. The lower end of the support arm 26 is free to move, for example resting upon part of the gutter 19 and so being free to move through an arc lying in a plane substantially parallel to the vent flap when the vent is closed. The drive mechanism 24 is mounted in a fixed position along the length of the support arm 26, conveniently at or close to a midpoint of the support arm 26, and so follows an arcuate path upon movement of the support arm 26.

A drive output from the drive mechanism 24 is connected via a universal joint 28 to an output shaft 30 which is, in turn, connected via a second universal joint 32 to the roller tube 22. It will be appreciated, therefore, that operation of the drive mechanism 24 serves to drive the roller tube 22 for rotation, opening or closing the vent.

In use, starting from the closed position illustrated in Figure 1, if it is desired to open or partially open the vent then the drive mechanism 24 is operated to cause rotation of the output shaft 30 and thereby drive the roller tube 22 for rotation. As explained hereinbefore, the rotation of the roller tube 22 causes the vent flap 20 to become wound upon the roller tube 22, and as the end of the vent flap 20 remote from the roller tube 22 is secured in a fixed position the winding of the vent flap 20 onto the roller tube 22 causes the roller tube 22 to displace or translate, following a path defined by the shape of the adjacent hoops 14 to open or partially open the vent.

As the roller tube 22 is secured to the drive mechanism 24 by way of the output shaft 30 which is of a fixed length, the initial movement of the roller tube 22 urges the drive mechanism 24 to move sideways, remaining spaced from the end of the roller tube 22 by a fixed distance, the sideways movement of the drive mechanism 24 being accommodated by the drive mechanism 24 being mounted upon the support arm 26 which is pivotally movable relative to the polytunnel structure. Accordingly, until the roller tube 22 has reached a half open position (see Figure 2) the movement of the roller tube 22 will cause the support arm 26 and drive mechanism 24 to swing, about the pivotal mounting of the support arm 26, away from the vent. After the half open position has been passed, continued movement of the roller tube 22 will cause the drive mechanism 24 and support arm 26 to swing in the opposite direction, back towards the vent until the fully open position is reached as shown in Figure 3.

It will be appreciated that the point at which the support arm 26 ceases swinging away is from the vent and commences swinging back towards the vent will depend upon the position of the drive mechanism 24 upon the support arm 26. If the drive mechanism 24 is located closer to the top of the support arm 26, then during opening movement the swinging of the support arm 26 away from the vent will continue for longer, and so the arc of movement of the support arm 26 may be increased.

Closing movement of the vent is achieved by rotating the roller tube 22 in the reverse direction.

Figure 4 is a photograph illustrating an installation of a drive arrangement of the type described hereinbefore with reference to the diagrammatic representations shown in Figures 1 to 3 and operates in substantially the same manner.

It will be appreciated that the drive arrangement described hereinbefore is of relatively simple and convenient form. It does not require the integrity of the gutter to be interrupted and does not require the use of relatively complex telescopic drive couplings. It may be retrofitted relatively easily to existing structures. By having the support arm movable in substantially the same plane as that occupied by the vent, it will be appreciated that the drive arrangement projects into the polytunnel by only a small distance.

In the description hereinbefore the drive mechanism comprises a motor and gearbox. It is also envisaged that the invention may be employed in arrangements in which a vent is manually driven between its open and closed positions. In such arrangements, the drive mechanism may comprise a gearbox and means whereby the gearbox may be driven manually.

Whilst the vent is described herein as being located in the roof of the structure, it will be appreciated that the invention is not restricted in this regard and is also applicable to arrangements in which the vent is located elsewhere, such as in a side or end wall of the structure. Further, whilst described in the context of driving a movable vent roller tube for rotation, the invention may be applied to the driving of other movable components.

Although the support arm is described as being pivoted as its upper end, and this will often be desirable, it could be pivotally mounted about its lower end or about other points along its length.

Although described in relation to polytunnels, it will be appreciated that the invention may be used in other applications, for example in adjusting the ventilation of greenhouses, marquees, tents or the like.

The description hereinbefore relates to one 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 drive arrangement comprising a support arm pivotally mounted to a support structure, a drive mechanism mounted upon the support arm at a fixed position along the length thereof, the drive mechanism having a drive output, and an output shaft connected to the drive output by way of a universal joint.
2. An arrangement according to Claim 1, wherein the support arm is supported for pivotal movement in a substantially fixed plane.
3. An arrangement according to Claim 2, wherein the said fixed plane is substantially parallel to a vent movable, in use, by the drive mechanism, when the vent occupies its closed position.
4. An arrangement according to any of the preceding claims, wherein the drive mechanism comprises a motor.
5. A structure according to Claim 4, wherein the motor is an electrically powered motor.
6. A structure according to Claim 4 or Claim 5, wherein the drive mechanism further comprises a gearbox.
7. A structure according to any of Claims 1 to 3, wherein the drive mechanism comprises a gearbox with a manual drive input.
8. A structure comprising a support structure carrying a flap of a flexible material, a roller tube connected to a free end of the flap, and a drive arrangement as claimed in any of the preceding claims and operable to drive the roller tube for rotation.s
9. A structure according to Claim 8, wherein the structure is a polytunnel.
10. A structure according to Claim 8 or Claim 9, wherein the flap is a vent flap.