FR2521827A1 - Inflatable greenhouse screen deployment and retraction device - has inflatable chambers controlled by cylindrical pistons to move thermal screens without sticking - Google Patents

Abstract

The tunnel greenhouse structure incorporates arches (1) distributed along its length and interconnected by lateral stringers (2) and a ridge stringer (3). The device is designed to deploy and retract one or more thermal screens (40) using extensible air chambers (31) moving along and around guide archways (4). Around and beneath the cylindrical piston (32) which forms the moving end of each chamber (31), in the retracted position, a deformable membrane (42) carried by a plastic sleeve (33) and brought into contact with the periphery of the chamber, slows down the deployment of the chamber when inflated. This device ensures a good distribution of air in the inflated part of the chamber, and prevents it from being rolled around the guide archway while the screen is deployed.

Description

Device for deploying and folding up one or more heat shields in a greenhouse.

 The present invention relates to a device for deploying and folding in a greenhouse one or more heat shields.

 The technical sector of the invention is that of cultivation greenhouses, for example tunnel greenhouses and more particularly means for installing and removing heat shields inside said greenhouses.

 We know the difficulties encountered when it comes to the establishment and removal of heat shields in greenhouses.

 These difficulties and the means to solve them have been explained in application 81 24035, according to which the screens are pulled by cellars and are carried by guide lines, in this case flexible rods adopting the form of arches.

 Despite the advantages of the means described in said application, certain minor drawbacks appeared which had to be remedied in order to obtain the perfect functioning of the device for installing and removing the screens.

 It has indeed appeared that the functioning of said screens was disturbed due to various factors causing the sticking of the screens on their supports: humidity due to condensation in the greenhouse; static electricity; surface condition of the supports.

 The objective of the present invention is to remedy these operating faults by inserting, between the screens and their supports, intermediate elements whose function is to cancel the bonding effect of the screens and their supports.

 This objective is achieved by the device according to the invention for deploying and folding in one greenhouse one or more thermal screens carried by guide lines, arranged inside the greenhouse and extending from the foot of the arches to the ridge of the greenhouse, which screens are fixed by their longitudinal edge lower than the foot of the guide lines and are subjected to means for moving along said lines, their free longitudinal edge, for deploying or folding them, characterized in that it comprises sliding and ex expandable sleeves, surrounding said guide lines, so that the screen is in contact with said sleeves to prevent the screen from adhering to its support during its handling.

 In one embodiment, each guide line is surrounded by an elastic wire wound helically around said line and is fixed on the one hand to the foot of the guide line and on the other hand to the free longitudinal edge of the screen .

 In another embodiment, the sleeves are air chambers fixed at the foot of the guide lines and comprising at their free end, a piston pierced in its center to slide on said lines, to which pistons is fixed the free longitudinal edge of the 'screen; in that the pistons also comprise hooking means for holding the deployed screen at the end of the stroke and means for bringing the screen back to the folded position and in that it also comprises means for blowing air in said chambers.

 In another embodiment, it comprises, around certain guide lines, two air chambers, one of which of smaller section is engaged in the other of larger section, which chambers are on the one hand fixed to the foot of the guide lines and secondly audit. piston to which the screen is attached.

 The result of the invention is the installation and removal of heat shields mounted in greenhouses and more particularly in greenhouses-tunnels.

 Because the screens are carried by extendable sleeves sliding on guide lines, for example metal rods, their installation and removal is carried out in excellent conditions, the screens no longer being braked in their operation by adhesion to their supports, due to condensation in the greenhouse, static electricity or their surface condition.

 In their embodiment with air bags, several screens and even several greenhouses are very easily actuated from a source of air circulated by means of a low pressure fan or by any other equivalent means.

 Independently of these inherent advantages in pneumatic operation, the air device makes it possible to establish an air circulation in the volume delimited by the screen, which can be of considerable interest in the case of certain cultures and also forms an air cushion to carry the screen by blowing.

 The choice of permanent magnets to hold the deployed screens is interesting because of the low investment of the means used and the simplicity of these means.

 The magnets also make it possible to fold the screens with ease by creating a depression in the air bags which have a frame or that known as bellows.

 Extensible sleeves have been called all means surrounding the guide lines such as low-force springs, slides, air chambers and all other similar means making it possible to avoid contact with the screens and their supports in order to alleviate the effects mentioned above, causing the malfunction when installing and removing the screens.

Other advantages and characteristics of the invention will become apparent on reading the description of various non-limiting embodiments of the device according to the invention, with reference to the drawing in which
- Figure 1 is a cross-sectional view of a serretunnel whose screens are put in place and folded from mechanical means and whose sliding of the screens on their support is improved by the presence of a spring surrounding the rods curved which make up the support of screens;
- Figure 2 is a cross-sectional view of a serretunnel whose screens are put in place and are folded from pneumatic means locking at the ridge of the greenhouse; the air supply is carried out by means of two collectors located at the feet of the support arches;
- Figure 3 is a sectional view of the greenhouse of Figure 2, the screens are locked at any point, the pistons coming into opposition cooperating together;
- Figure 4 is a sectional view of a greenhouse tunnel whose screens are set up and folded from pneumatic means whose screen supports are tubes to allow air distribution on the side of the feet of said supports; the air supply being carried out by means of a collector situated under the ridge of the greenhouse; the screens lock on said collector;
- Figure 5 is a partial sectional view of a greenhouse tunnel whose screens are set up and folded from pneumatic means, the air chambers being bellows sleeves;
- Figure 6 is a partial sectional view of a serretunnel whose screens are put in place and folded by means of a pneumatic device and comprising two air chambers, one of which of smaller section has a frame and is engaged in the 'other of stronger section; when the screen is deployed, the air pressure acts on the entire surface of the piston, the air being blown into the two chambers; during folding, the vacuum is only active in the central air chamber;
- Figure 7 is a partial sectional view of a serretunnel whose screens are put in place and folded by means of a device similar to that of Figure 6; according to this example, the interior air chamber is a bellows sleeve.

 Reference is first made to FIG. 1 of the drawing which schematically illustrates a greenhouse in cross section. This consists of a structure composed of hangers 1, distributed over its length and connected together by lateral beams 2 and a beam 3 fixed to the ridge of the greenhouse. The greenhouse cover, made for example of translucent plastic material is fixed to said structure.

 According to one embodiment which has been the subject of patent application 81 24035, the device comprises several arches 4, distributed inside the greenhouse and extending in the transverse direction.

Each arch preferably consists of two curved rods 4a, fixed to a fitting 5, itself fixed to the beam 3. These arches 4 are intended to support the screens 6. These produced for example from a film of metallized polyester and infrared treated on one or two sides, are intended to be stretched over the plants being supported by the poles 4, as illustrated on the right of Figure 1, or to be folded at the foot of the poles 4 and between these and the base of the hangers 1 of the greenhouse, as shown to the left of said figure. The screens 6 are in the form of rectangular sheets whose lower longitudinal edge 6a is fixed to the foot of the greenhouse. their upper longitudinal edge 6b comprises at each end a weight 7 intended to promote the folding of the screens when they are removed.

 The deployment of the screens 6 above the plants is obtained by means of cables 8, attached to the ends of their upper edge 6b, which cables are wound around one or more winches to cause the simultaneous placement of the screens 6 in the tight.

The screens 6, for their deployment, are drawn, for each screen, by means of two sets of two pulleys with grooves 9/10, around which the cables 8 are wound, attached in the
extension of the side edges of the screen and each set of pou
lees is carried by a slide 11 moving on a line of mistletoe
dage 12, tensioning by means of tensioners 13. In order to avoid that
the screen 6 does not stick to the curved rods 4a, these include a man
extensible chon 14 which, in one embodiment, consists of
a wire wound helically around said rods 4a in the manner of a
This is fixed on the one hand to the foot 14a of the supports and
on the other hand at the edge 6b of the screen. The constituent wire is a
small section, for example of the order of îmm2 and the diameter of the hose
Lement is relatively strong compared to the section of the upper rods
port, for example in the ratio of 1 to 100, so that
when the screen is deployed above the crops, the spring has the
capacity to extend over the length of the hangers 4a and that when the screen 6 is folded, the spring 14 winding with contiguous turns, occupies a minimum of space at the foot of the supports 4.

In this design, the wire interposed between the guide rod
4a and the screen 6 prevents it from adhering to its support under the effect of moisture due to condensation in the greenhouse, to static electricity.
tick or surface condition of the support.

 In another embodiment (FIG. 2), the extensible sleeve, making it possible to alleviate the aforementioned effects, is an air chamber fixed to an air manifold 16, disposed at the foot of the guide rods 4a. The collector 16 comprises nozzles 16a forming necks around which the sleeves 15 are fitted by their lower end, the fixing being carried out by means of clamps.

 For example and as shown in the drawing, the rods 4a pass through the collectors 16 and are engaged in the housing t6b extending at the bottom of the collectors and stuck in the ground.

At their free end, the sleeves 15 include a piston
17, drilled in its center to slide along the guide rod 4a. The sleeve 15 is fitted around the piston 17 whose external contour can take any shape, but is preferably of a circular contour. The screen 6 is fixed on the one hand to the foot of the hoops of the greenhouse, for example to the collector 16, at 6c, and on the other hand to the pistons 17 at 6d. Two or more air chambers may be necessary for the screens to function properly.

 Maintaining the deployed position of the screens 6 is obtained by means of permanent magnets 18 cooperating with metal parts having magnetic properties, for example mild steel. These parts are plates fixed either to some of the pistons: those opposite to the pistons which comprise the permanent magnets, or plates 19 fixed to the frame of the greenhouse.

 The drawing illustrates in Figure 2 an embodiment of such a device whose magnets 18 are fixed to the piston 17 to cooperate with the plate 19, located in the longitudinal median plane at the ridge and inside the greenhouse. It is understood that, in a variant, the piston could just as easily be equipped with a metal plate to cooperate with permanent magnets fixed to the support 19.

 For correct operation of the device, the magnets are at least two in number and in this case, diametrically opposite and preferably symmetrically.

The air admitted from a source of forced air, for example a low pressure fan (not shown) in the manifold 16, is introduced into the air chambers 15. The pressure build-up tends to cause the displacement of the piston 17 along the guide rods 4a, driving the screen 6. At the end of the upper stroke, the piston arriving at the level of the plate 19 is pressed, under the effect of the magnets 18, on the latter. In this position, the screen is deployed as illustrated on the right in Figure 2,
FIG. 3 represents a greenhouse tunnel 1, the screens 6 of which are deployed inside to completely cover the crops.

In this embodiment, the piston 17 fitted to the air chamber situated on the left, comprises permanent magnets 18, the piston 171 which composes the sleeve 151, situated on the right, comprises a mild steel plate 19. According to the example shown , the screen 61 is fully deployed, which has the effect of covering the crops beyond the longitudinal axis of the greenhouse. The screen 6 is therefore partially deployed.

 This design makes it possible, under certain conditions, to conceal crops in whole or in part to form gray areas by equipping greenhouses with aluminized screens and infrared treated on both sides.

 Referring now to Figure 4 of the drawing which illustrates another embodiment of the device according to the invention. The air chambers 15 are fitted by their lower end around anchoring parts 20 comprising at their lower part a housing 20a in which the guide rod 4a is engaged. This is a tube of small section whose the end, located on the side of the part 20, has perforations 4b at its periphery.

 Like the sleeves of Figures 2 and 3, those of Figure 4 are fixed around the pistons drilled in their center to move along the guide rods 4a. The air is supplied by a central manifold 21, located in the greenhouse and under the ridge of the latter and into which the manifold opens the guide tubes 4a. Mild steel plates 22, applied against the collector, have the function of receiving, during the deployment of the screens 6, the piston 17, which comprise, like those of the preceding figures 2 and 3, permanent magnets 18.

 The air blown by a low pressure fan, or any other similar device, is distributed by the air network consisting of the manifold 21 and the guide tubes 4a to be introduced into the air sleeves 15 through the orifices 4b . Under the effect of the increase in air pressure in the sleeves 15, the pistons 17 are moved by driving the screens 6 until the pistons are stuck by magnetization on the plates 22.

 According to a variant shown on the right of FIG. 4, the air bags 15 comprise, on the side of the pistons 17, orifices 15a, of small section, to create leaks and achieve two results, obtaining a circulation of fresh air in the volume. delimited by screen, and this in the context of the breeding of certain plants, and also to make carry the screen by an air cushion and cause the distance of the screens compared to the guide rods 4a not comprising a sleeve 15 This design makes it possible to reduce the number of hoops equipped with air bags 15. Said air bags are of a circular or oval cross section.

 In one embodiment, they are in the form of sleeves made from a plastic film, for example polyester or any other similar material. Such sleeves have the advantage of having a low investment but when the screens are removed their folding is done in an anarchic manner.

 To overcome this drawback, the device according to the invention is equipped with sleeves comprising a frame constituted by a helical spring 15b, arranged inside or in the thickness of their wall to promote the retraction of the sleeves and keep them in good condition. position relative to the guide rod.

 As a variant, the device according to the invention is equipped with bellows sleeves which have the advantage of being folded up under good conditions.

The folding of the screens is preferably obtained by creating a vacuum in the air chambers under the effect of said fan.
at low pressure or by any other similar device. According to this conception, the depression must be greater than the force of attraction
permanent magnets to cause the magnets to take off and the
removal of the screens with a view to their folding at the foot of the arches. In
the purpose of promoting the operation of the device, the pistons 17 can be ballasted. Only 15 air chambers with an arma
ture or being constituted by a bellows sleeve are capable of
radially resist the effects of an air depression created in
their internal volume. For single rooms with no frame, their takeoff for folding screens is done manually. For fwcitrterltopération, the device can include
attached cords; pistons 17 and accessible from the ground.

FIG. 5 illustrates a device whose air chamber is
a bellows sleeve 152. This is mounted, like the sleeve 15,
illustrated in Figure 2. It has a sufficient number of bellows
so that it can extend along the guide rods 4a. When the screen is folded, the adjoining bellows are brought back For a small footprint at the foot of the hanger 4. In one embodiment,
such sleeves are made from a synthetic material
for example an elastomer. Armed or not, said sleeves are capable of radially withstanding a depression in order to cause the
take off of the magnets 18 during the folding of the screen 6.

 Figures 6 and 7 illustrate another embodiment of the device according to the invention and according to two alternative embodiments.

As illustrated in FIG. 6, the device comprises, around
certain guide rods 4a, two air chambers, one of which more
small section 153 is surrounded by another -23 stronger chamber
section.

Chamber 153 is fitted at the bottom of guide rods 4a in
a nozzle forming a neck 24 extending around the periphery of the collectors
air 16. The neck 24 has, at its free end, a wall 24a,
pierced in its center, to receive the guide rod 4a as well as holes 24b reserved around said central hole. The chamber 153 is fixed to the end of the neck 24 by means of a clamping collar 25. Below the location of said collar, the neck 24 has holes 24c made in its wall between the collar and the birth of the collar. The chamber 23, which is of larger section, is attached below the holes 24c, by means of another clamp 26.

 The piston 27, to which the chambers 153 and 23 are attached, comprises, at its central part, which is pierced to allow the passage of the guide rod 4a, a boss 27a around which the free end of the chamber 153 is fitted, which is fixed by means of a collar 28.

 The chamber 23 is fitted around the piston 27 and is fixed by a collar 281.

 Chambers 153 and 23 are of indifferent section: circular, oval or other. They are, however, preferably cylindrical.

 The central air chamber 153> preferably has an armature constituted by a helical spring 29 or any other technical equivalent such as, for example, rings ...

 Like the previously described devices, the screen 6 is fixed on the one hand to the base of the greenhouse and on the other hand to the pistons 27.

 To deploy the screen 6, the air passing through the manifold 16 is blown into the two chambers 153/23. The total surface of the piston is concerned. The screen is carried by the chamber 23, which is made from a light film, for example polyester.

 The chamber 153, like the chambers 15 described above, has the frame 29. This chamber is more specially adapted for folding the screen 6. To do this, a depression is created in the said chamber i53 to bring the screen 6 back to the foot of the greenhouse.

 The device of FIG. 7 is similar to that of FIG. 6 as regards its essential elements.

 In this version, the central chamber 30 is a bellows sleeve fixed to the piston 27 and to the manifold 16 in the same way as that described with reference to FIG. 6. The sleeve 30 is for example very similar to that described in FIG. -5.

 As a variant, the chamber 23 is perforated on the side of the piston 27 to create air leaks 31 in order to circulate the fresh air below the screen 6 and to carry it by blowing.

 The invention is not limited to the description which has just been.

made with reference to the figures in the drawing, but extends to all possible combinations of the elements described.

Claims (19)

 1. Device for deploying and folding in one greenhouse one or more heat shields (6), carried by guide lines (4a), arranged inside the greenhouse (1) and extending from the foot of the arches to the ridge (3) of the greenhouse, which screens (6) are fixed by their lower longitudinal edge (6c) at the foot of the guide lines and are subjected to means for moving along said lines (4a), their free longitudinal edge (6d ) to deploy or fold them, characterized in that it comprises extendable sliding sleeves (14/15/152/153 / 23/30), surrounding said guide lines (4a)> so that the screen ( 6) is in contact with said sleeves (14/15/152/153/23/30) to avoid adhesion of the screen (6) on its support (4) during its handling.  2. Device according to claim 1, characterized in that each guide line (4a) is surrounded by an elastic wire (14), wound helically around said line (4a) and is fixed on the one hand to the foot of the guide line (4a) and on the other hand to the free longitudinal edge of the screen (6b).  3. Device according to claim 2, characterized in that the wire (14) is of a very small section and its winding diameter is large relative to the section of the guide lines (4a), so that d firstly, when the screen (6) is deployed, the wire (14) can extend over the length of the guide line (4a) and secondly when the screen (6) is folded, the sleeve (14), the turns of which are then contiguous, occupies the minimum space at the foot of said guide lines (4a) for obtaining the maximum folding of the screen (6).  4. Device according to claim 1, characterized in that the sleeves (15/152/153) are air chambers fixed to the foot of the guide lines (4a) and comprising at their free end a piston (17), drilled in its center for sliding on said lines (4a), to which pistons is fixed the free longitudinal edge (6d) of the screen (6); in that the pistons also comprise hooking means (18) for holding the deployed screen at the end of the stroke and means for bringing the screen (6) back to the folded position and in that it further comprises means for blowing air into said chambers.  5. Device according to claim 4, characterized in that the air chambers (15/152) are fixed on necks extending orthogonally to the periphery of the air collectors (16), arranged at the foot of the guide lines ( 4a) to blow air into the chambers (15/152) and cause the pistons (17) to move and the screen (6) to deploy.  6. Device according to claim 4, characterized in that the guide lines (4a) are tubes closed at their end driven into the ground and opening into an air collector (21) extending under the greenhouse , which tubes (4a) have at their periphery and on the side of their lower end stuck in the ground, perforations (4d) to breathe air into the air chambers (15) and cause the displacement of the pistons (17) and the deployment of the screen (6).  7. Device according to any one of claims 4 to 6, characterized in that the air chambers (15) are perforated at their end located on the side of the piston (17) to create air leaks and establish a circulation d fresh air in the volume defined by the screen (6) and form an air cushion to carry the screen (6) by blowing.  8. Device according to any one of claims 4 to 7, characterized in that the attachment means for holding the screens (6) deployed are permanent magnets (18) cooperating with metal parts (19/22) having magnetic properties, fixed to the greenhouse or to the pistons (171) which are in opposition to those (17) which include the magnets (18).  9. Device according to any one of claims 4, 5 and 8, characterized in that said metal parts (19) are-mild steel plates, fixed to the greenhouse and extending below the fate of it- ci in the median longitudinal plane of the greenhouse, so as to bar the path of the pistons (17).  10. Device according to any one of claims 4, 6 and 8, characterized in that the metal parts (22) are mild steel plates, fixed to said air collector (21) and to the tubes (4a) constituting the guide lines, so as to bar the path of the pistons (17).  11. Device according to any one of claims 4 to 10, characterized in that the air chambers (14/153) comprise a metal frame (15b / 29), which is arranged inside the chambers (15/153 ).  12. Device according to any one of claims 4 to 10, characterized in that the air chambers (15/153) comprise a metal frame (15b / 29), which is integral with the wall of the chambers (15/153) .  13. Device according to any one of claims 4 to 10, characterized in that the air chambers (152/30) are bellows sleeves.  14. Device according to claim 4, characterized in that it comprises around certain guide lines (4a) two air chambers (153 / 30-23) of which one (153/30) of smaller section is engaged in the '' other (23) of larger section, which chambers (153 / 30-23) are on the one hand fixed to the foot of the guide lines (23) and on the other hand to the piston (27) to which the screen is attached (6).  15. Device according to claim 14, characterized in that the air chamber of smaller section (153) comprises a metal frame (29), which is arranged inside the chamber.  16. Device according to claim 14, characterized in that the air chamber of smaller section (30) is a bellows sleeve.  17. Device according to any one of claims 14 to 16, characterized in that the larger section chamber (23) has perforations (31) located on the side of the piston (27) to create air leaks and establish a circulation of fresh air in the volume delimited by the screen (6) and to form an air cushion for carrying the screen (6) by blowing.  18. Device according to any one of claims 14 to 16, characterized in that the larger section chamber (23) is made from a porous textile material to promote the passage of air.  19. Device according to any one of claims II to 16, characterized in that the folding of the screens (6) in the greenhouse is obtained by creating a vacuum in the bellows air chambers (152/30) or which include a armature (15/153).