FR3068569A1 - AGRICULTURAL GREENHOUSE WITH MEANS FOR TENSIONING ITS COVERING WALL - Google Patents

Abstract

The invention relates to a greenhouse for growing food crops comprising a frame (1) forming a roof structure with a ridge (12). The framework is completely covered by a flexible cover (2) determining in combination with the vault structure two roof panels (20) extending from the ridge (12) downwards, which sections are fixed by their horizontal bottom edge fastening systems (13) that includes the frame (1). The greenhouse comprises means for tensioning the cover (2), independent of the two fastening systems (13), which are arranged at a distance from said tensioning means (3) of the cover (2).

Description

AGRICULTURAL GREENHOUSE WITH MEANS OF TENSIONING ITS COVER WALL

Technical area

The present invention is in the field of agricultural installations and relates more particularly to a greenhouse adapted to the cultivation of food crops and other plants, equipped with an improved means of tensioning its cover.

State of the art

Typically, greenhouses used in the agricultural field are formed of a metal frame anchored to the ground and a transparent cover to the light affixed and stretched on the frame. This cover determines, in combination with the framework, a sheltered volume, usually in the form of a tunnel in which food crops are grown. The cultivation of these plants is carried out either in the ground or above ground, in suitable receptacles.

The framework of such greenhouses is usually constituted by a plurality of metallic framework elements, erected vertically on the ground, each forming arches at least in the upper part. These framework elements are anchored to the ground by their lower ends. Furthermore, these frame elements are joined to each other by horizontal side rails and by one or more ridge elements materializing the ridge line of the tunnel formed by the greenhouse.

The roof, in association with the framework, forms on both sides of the ridge, two roof sections, inclined from said ridge towards the ground. Each roof section is usually fixed along its lower horizontal border to a horizontal element of the greenhouse frame. This horizontal fixing element is usually made up of a profile with a longitudinal groove intended to receive the greenhouse cover as a fixing. The fixing of the cover is usually ensured by locking keys engaged in the groove of the profile to pinch the cover.

It is necessary that the cover is properly stretched over the frame in order to avoid any folds that could lead to the formation of rainwater and dust retention zones. For this reason, when fixing the cover to the horizontal fixing elements, a mechanical tension is exerted manually on said cover so that the latter, after fixing, remains perfectly stretched on the frame and has a smooth and regular appearance. But it turns out that the tensioning of the cover makes it difficult to fix the cover. This can result in faults such as improper fixation or non-uniform fixation. In addition, it has become apparent that the commonly used fastening elements lack reliability over time so that the cover can gradually relax and then have an unwanted propensity to beat in the wind. This drawback very often results in the premature deterioration of the roofing under the effect of repeated shocks against the frame of the greenhouse.

The cover of a greenhouse is usually formed by a flexible wall of synthetic material transparent to light, waterproof and air, but it can also be formed by a net. The cover can also be formed by two flexible walls, made of synthetic material, transparent to light, waterproof and airtight, arranged in a superimposed manner, determining between them one or more sealed chambers intended to be inflated with pressurized air. Such a configuration provides the greenhouse with thermal insulation by forming a double-wall system and an air cushion of insulation between the walls.

Greenhouses equipped with covers forming double walls are known from the prior art. In this regard, we can cite the document FR 2 315 844 (SEBA) which shows a greenhouse whose cover forms, on either side of the ridge line, two sealed chambers under air pressure. More specifically, the cover is formed of two juxtaposed films joined by their edges, in particular to the channels. Furthermore, these two films rest by their median zone on the corresponding ridge. The chambers thus formed are inflated by pressurized air, and determine the two sections of roof that comprise the greenhouse. These two chambers are in communication relationship with each other so that it is not possible to simultaneously maintain one of them in an inflated state and the other in a deflated state. Such a configuration would find its interest in particular at certain times of the day in particular in the early hours of the day in order to let pass a maximum of luminosity and calorific rays through the roof panel exposed to the east by emptying the latter's room all his looks.

Statement of the invention

The object of the present invention is to solve the aforementioned drawbacks by proposing a greenhouse provided with simplified tensioning means for its cover able to keep the cover taut whatever the degree of defectiveness or weakening of the fixing of said cover to the backbone.

Another object of the present invention is a greenhouse whose cover, in combination with the framework, forms two roof sections, each arranged in double walls, each determining a sealed chamber intended to be inflated or deflated on demand and this of independently of the room on the other side. Thus, one of the roof sections can be kept in an inflated state while the other is kept in a deflated state.

Another object of the present invention is a greenhouse for which the side panels are always kept in tension whether they are in an inflated state or else in a deflated state.

To this end, the greenhouse according to the invention comprising a metal supporting framework forming an arch structure at least in the upper part, formed of successive parallel arches, which arch structure is carried by posts anchored to the ground, has a ridge element and is completely covered by a flexible cover having two large opposite faces, one of which, lower, faces the internal volume of the greenhouse and the other, upper, faces outside of said volume, said cover determining in combination with the arch structure, two roof sections extending from the ridge element downwards, which roof sections are fixed by their horizontal lower edge to two lateral fixing systems which the framework comprises on either side of the arch structure, rainwater drainage gutters being arranged to be fixed on the frame on either side another of said arch structure is essentially characterized by a tensioning means the independent coverage of two fastening systems which are arranged remotely from said means for tensioning the cover.

Such an arrangement is capable of keeping the tarpaulin correctly stretched over the framework, regardless of the degree of loosening of the attachment of the tarpaulin to the fastening elements.

According to another characteristic of the invention, the tensioning means is configured capable of occupying, upon ordering, a retracted state according to which it exerts no tensioning effort on the cover and a deployed state according to which it exerts forces on said cover so that the latter is kept in tension between the two fastening systems, the forces applied to the cover being distributed along at least one line parallel to the ridge.

According to another characteristic of the invention, the or each tensioning means, at least in its deployed state, forms additional thickness on the arch structure.

According to another characteristic of the invention, the or each tensioning means acts on at least one large face of the cover and exerts on said large face normal forces of thrust and or traction.

According to another characteristic of the invention, the or each tensioning means is parallel to the ridge.

According to another characteristic of the invention, the at least one or more tensioning means runs along the ridge of the arch structure and is fixed to the latter.

According to another characteristic of the invention, the ridge is arranged in a fixing profile, the tensioning means (3) being fixed to said profile.

According to another characteristic of the invention, the or each tensioning means is arranged under the cover (2).

According to another characteristic of the invention, at least one tensioning means is integrated in the cover.

According to another characteristic of the invention, the or each tensioning means consists of at least one elastic rod, of elongated shape, radially expandable, arranged in contact with the cover.

According to another characteristic of the invention, the or each tube has at least one sealed internal chamber and receives in said chamber a gaseous fluid under pressure which urges it in radial expansion, said gaseous fluid being supplied by a source of gaseous fluid connected to said chamber by a supply line.

According to another characteristic of the invention, the tensioning means is constituted by two inflatable, parallel tubes, separated from each other by a longitudinal zone of attachment to the ridge element.

Alternatively, according to another characteristic of the invention, the or one of the tensioning means is covered by the cover and is constituted by arches which concavity is oriented downwards, said arches being formed in ridge, each between two arches of the arch structure.

According to another variant, the greenhouse cover is formed from a single flexible wall, the or each tensioning means being constituted by an inflatable tube formed by a sealed channel formed in said cover.

According to yet another variant of the invention, the cover is formed of two flexible walls, superimposed, lower and upper, fixed to each other by their longitudinal and lateral edges, forming in combination with the arch structure a first roof panel and a second roof panel both extending from the ridge downwards, the said roof panels each being formed from a bottom wall panel and an upper wall panel and each forming between the panels of lower and upper wall, a housing in which is disposed at least one means for tensioning the cover of the greenhouse, constituted by an inflatable, elastic tube extending parallel to the ridge line.

According to another alternative embodiment of the invention, the greenhouse cover is formed by two superposed flexible walls, lower and upper, fixed to each other by their longitudinal and lateral edges, forming in combination with the structure a first roof panel and a second roof panel both extending from the ridge downwards, the two flexible walls forming a housing in which is placed a tensioning means constituted by an elastic inflatable tube. In addition, the inflatable tube is arranged in line with the ridge element parallel to the latter and the tensioning means is held in place in line with the ridge element by long, lateral links fixed on the one hand to said means. tensioning and secondly to the fastening elements.

Preferably according to another characteristic of the invention, the cover is formed by two flexible walls which are waterproof and airtight, superimposed, lower and upper, fixed to each other by their longitudinal and lateral edges, forming, in combination with the roof structure, a first roof panel and a second roof panel both extending from the ridge downwards, the said roof sections each being formed from a bottom wall panel and a upper wall section and each forming between the lower and upper wall sections, a sealed chamber intended to be inflated with a gaseous thermal insulation fluid, under pressure, said roof sections being fixed by their horizontal lower edge to the fixing elements and each comprising at least one pressurized fluid supply mouth of their sealed chamber, said mouth being connected to a source of fluid under pressure through a non-return valve.

According to another characteristic of the invention, the check valve comprises a valve body comprising a through bore or track, a seat at one of the ends of the track and a sealed shutter, and biased towards the seat, that is to say towards a closed position under the effect of the pressure and the shutter is formed by a flexible membrane provided with a leak indicator element.

According to another characteristic, a greenhouse of the multi-tunnel type, each tunnel of which comprises two lateral gutters, is remarkable in that the gutters of each tunnel are each formed by an inflatable tube, the latter comprising a sealed chamber designed to receive a gaseous fluid under pressure and in that the inflatable tubes facing two consecutive tunnels coming into pressure against one another under the effect of their inflation to form at least one flow channel of the water, the two so-called tubes of one and the other tunnel, by deflation, releasing an air opening.

According to another characteristic of the invention, each roof pan by the cover rests on at least one support element arched substantially in the shape of a U, fixed by its two ends to the corresponding channel, the support element being parallel to said roof pan and resting by its summit area on one of the arches of the framework.

Brief presentation of figures and drawings

Other advantages, aims and characteristics of the invention will appear on reading the description of preferred embodiments, given by way of nonlimiting example with reference to the appended drawings in which:

FIG. 1 is a plan view of a multi-tunnel greenhouse according to a first embodiment of the invention,

FIG. 2 is a plan view of a single-tunnel greenhouse according to the invention,

FIG. 3 is a sectional view of the profile constituting the hoops of the greenhouse,

- Figure 4 is a sectional view showing the method of fixing the cover of the greenhouse in the groove of the arch corresponds,

- Figure 5 is a sectional view of a cover fixing system,

FIG. 6 is a diagram showing the pneumatic supply of a tensioning means in the form of an inflatable tube,

FIG. 7 is a sectional view showing the method of attachment to the ridge element of the tensioning means in the form of an inflatable tube,

FIG. 8 is a top view of the method of attachment according to FIG. 7,

FIG. 9 is a schematic view showing another embodiment of the means for tensioning the cover,

FIG. 10 is a view of a single-tunnel greenhouse, the cover of which forms an inflatable double wall,

FIG. 11 is a schematic view of an installation for supplying gaseous fluid according to a first embodiment of a greenhouse with inflatable wall sections,

FIG. 12 is a schematic view of an installation for supplying gaseous fluid according to a second embodiment of a greenhouse with inflatable wall sections,

FIG. 13 is a diagram of an installation for supplying gaseous fluid according to a third embodiment of a greenhouse with inflatable wall sections,

FIG. 14 schematically shows an greenhouse with inflatable sides according to FIG. 13, the pan of which faces east is in a deflated state,

- Figure 15 is a sectional view of an emptying mouth in the closed position,

- Figure 16 is a sectional view of a drain opening according to Figure 15 in the open position,

FIG. 17 is a top view of the emptying mouth according to FIG. 15 or FIG. 16,

- Figures 18 and 19 are perspective views, respectively from above and from below of a non-return valve,

FIGS. 20 and 21 are perspective, exploded views, respectively from above and from below of the non-return valve according to FIGS. 18 and 19,

FIG. 22 is a sectional view of a non-return valve in the closed position,

FIG. 23 is a sectional view of a non-return valve in the open position,

FIG. 24 is a sectional view of a solenoid valve, in the closed position, formed from the non-return valve according to FIGS. 18 and 19,

FIG. 25 is a sectional view of the solenoid valve according to FIG. 24, in the open position,

FIG. 26 is a sectional view of a solenoid valve intended to be located between the two inflatable sections of a greenhouse tunnel,

- Figure 27 is a schematic sectional view of a second embodiment of a double-walled covering intended to equip the or one of the tunnels of a greenhouse according to the invention, only the elements essential to understanding of this figure are represented on the latter,

FIG. 28 is a schematic sectional view of a third embodiment of a double-walled cover, provided for fitting out one or more of the tunnels of a greenhouse according to the invention,

FIG. 29 is a sectional view of a cover according to a fourth embodiment,

FIG. 30 is a top view of a cover according to a fifth embodiment,

FIG. 31 is a diagrammatic view of an installation for supplying gaseous fluid with a gutter consisting of an inflatable tube,

FIG. 32 is a partial view of two greenhouse tunnels with gutters constituted by inflatable tubes,

FIG. 33 is a plan view of a gutter in the form of an inflatable tube, in an inflated state, equipped with a compression element,

FIG. 34 is a plan view of the gutter according to FIG. 33, in a deflated state,

FIG. 35 is a sectional view showing a lateral ventilation system between two greenhouse tunnels,

FIG. 36 is a view on an enlarged scale of detail A in FIG. 35,

FIG. 37 is a perspective three-quarter front view of a ventilation system according to another embodiment,

FIG. 38 is a rear three-quarter view of the ventilation system according to FIG. 37,

- Figure 39 is a plan view of a greenhouse equipped with support elements of the cover,

- Figure 40 is a cross-sectional view of a support element. Best Ways to Carry Out the Invention

In Figure 1 is shown a greenhouse of the multi-tunnel type while in Figure 2 is shown a single-tunnel greenhouse. These greenhouses according to the invention each comprise a metal supporting frame 1 covered by at least one flexible protective cover 2 of rectangular shape, having two large opposite faces, one of which, lower, faces the internal volume of the greenhouse and the other , superior, is turned towards the outside of the said volume. These two types of greenhouse also have, each in association with the cover (s), and attached to their framework, two front and rear sides and two left and right side sides delimiting a volume protected from the weather in which food crops are grown. or other plants. As can be seen in FIGS. 1 and 2, a single-tunnel greenhouse is equipped with only one cover, while a multi-tunnel greenhouse is equipped with several covers 2, each of them ensuring the covering of 'one tunnel and one. As regards the multi-tunnel greenhouse, the left and right lateral flanks are carried respectively by the frame of the left tunnel and by the frame of the right tunnel.

Each cover 2 and each front, rear and lateral flank may consist of a protective net or of several superposed protective nets. These nets can be shade nets, insect-proof nets or any other type of net or permeable walls used in agriculture for the protection of cultivated areas and plants. The cover 2 and the front, rear and lateral flanks can also each be formed by a flexible wall which is transparent or opaque to light and impermeable to water and air, they can also be constituted by two superimposed flexible walls impermeable to water and air, preferably transparent to light, fixed to each other at least by their longitudinal and lateral edges.

The frame 1, as can be seen in particular in Figures 1 and 2, is formed of support posts 10, metal, of the same height, anchored to the ground in a known manner, for example by twisted piles. These posts 10 are arranged in parallel rows, and support two by two at the upper end, identical metal arches 11, forming, as regards a single-tunnel greenhouse an elongated arch structure and as regards a multi-greenhouse tunnels several elongated arch structures, parallel to each other.

Preferably, as shown in FIG. 3, each hoop 11, along its face intended to receive the cover in support, has at least one longitudinal groove 110 for ventilation. Such a groove by allowing natural ventilation of the arch prevents the latter from overheating and in the long term deteriorates the cover 2. Advantageously, the arch 11 has several adjacent grooves 110, for example three in number, Figure 3, to enhance the above effect. In addition to ventilation, these grooves 110 allow the evacuation of condensation water to the ground, but also when the cover 2 is formed by a water-repellent net, the evacuation of water flows liable to form in the contact zone between the roll bar and said cover.

Furthermore, due to the presence of the grooves 110, the contact surface between the arch 11 and the cover is reduced. Thus the heat exchange between the cover 2 and each hoop 11 by the contact surface is greatly reduced. Such a provision is likely to increase the life of the cover.

As regards each arch 11 at the end of each arch, the outermost groove 110 is used for fixing the cover 2 (FIG. 4). To this end, as shown in FIG. 4, the cover is introduced into the groove 110 and is blocked there by a pinching element 115 in the form of a substantially U-shaped section, provided with two parallel lateral wings and a basal wing. joined to the lateral wings, the said lateral wings being held in pressure against the cover by a locking key 116, of oblong cross section, introduced in clamping between the wings of the nipping profile 115. The purpose of this key is to oppose tightening of the lateral wings of the pinching element 115. The lateral wings of the pinching element 115, opposite the basal wing are each provided with a return at right angles forming a support wing. The pinching element 115 and the locking key are preferably made of an appropriate synthetic material.

Preferably, the constituent section of the arch 11 has four perpendicular walls two by two, namely a front wall 111, two side walls 112, and a rear wall 113. The grooves 110 are formed by deformation of the wall 111. The wall rear 113, opposite the wall 111 has a longitudinal slit 114, median, bordered by two right angle returns 114a both oriented towards the front wall 111. The side walls 112, parallel to each other, join the walls 111 and 113.

The arches 11 of each arch structure are joined to each other, in the upper part, by a ridge element 12, constituted by a metal profile. This metal profile is fixed everywhere known means to the corresponding arches and more precisely to the summit area of each of these. As can be understood, the ridge element 12 materializes the ridge line that comprises the corresponding arch.

On either side of the or each vault structure, at the lower end of the latter, on the posts 10, and this parallel to the ridge line, the frame 1 of the greenhouse receives lateral fixing systems 13 horizontal. These fixing systems 13 are fixed to the posts 10 of the frame or else to the hoops 11. These fixing systems 13 are provided for receiving the cover 2 in fixing and are each constituted by:

a rigid fixing profile 130, preferably metallic, comprising at least one longitudinal fixing groove 130a,

- A pinching element 131, in the form of a substantially U-shaped cross section, intended to be introduced into the groove 130a, said pinching element having two lateral wings and a basal wing, said lateral wings each being extended by a return at right angles forming a support wing,

- And a locking key 132, of oblong cross section intended to be engaged in tightening in the nipping element 131, between the two lateral wings of the latter, in order to oppose the tightening of said lateral wings and to maintain said pinch element 131 in pressure against the cover 2.

The pinching element 131 and the locking key 132 are made of a suitable synthetic material.

The cover 2, for its fixing, is engaged in the groove 130a and is held there in tightening by the pinching element 131 equipped with its locking key 132, this locking key opposing the tightening of the lateral wings of the clamping element.

Finally, the greenhouse frame 1, on either side of the or each vault structure, receives 6 horizontal drainage channels for fixing rainwater.

The arch structure as described receives the flexible protective cover 2, which is fixed in particular by its longitudinal edges, to the fixing systems 13.

The flexible protective cover 2, on the framework and more particularly on the arch structure, forms two roof sections 20a, 20b inclined downwards from the ridge element 12. These two roof sections, depending on the type of greenhouse can run to the ground, in which case the frame of the greenhouse is integrally formed by the arch structure. For other types of greenhouse, the roof structure is carried by independent posts 10 and the greenhouse under the fixing systems 13, may include lateral sides of the walls.

According to the invention, the cover 2 is subject to at least one tensioning means 3 parallel to the ridge line 12 of the greenhouse, said tensioning means 3 being able to exert normal forces on the cover 2 , oriented upwards or downwards, under the effect of the action of which said cover is tensioned.

Preferably these normal forces are distributed continuously along a line parallel to the ridge line and not punctually, which guarantees uniform tensioning of the cover 2. In addition this arrangement ensures the maintenance of the cover 2 in a stretched state even in the event of loss of effectiveness of the fixing of said cover to the fixing systems 13.

Still according to the preferred embodiment, the area of action of these forces extends substantially over the length of the cover 2, it being understood that this dimension of length is that parallel to the ridge line.

According to a first embodiment, the cover 2 rests on the tensioning means 3 and the latter acts on the large underside of said cover 2 and exerts therein normal upward pushing forces. The tensioning means is therefore under the cover and is protected by the latter. By large underside is meant that facing down and located opposite the internal volume of the greenhouse.

As a variant, the tensioning means 3 acts on the external face of the cover 2 and exerts therein normal traction forces directed downwards.

The tensioning means 3 can be constituted by a rigid elongate element applied against the cover 2 either by actuators, either by elastic members or by a combination of these two mechanical means, but, preferably, the setting means tension 3 is constituted by at least one elastic tube, of elongated shape, radially expandable, bearing on the arch structure and developing parallel to the ridge 12, this elastic tube 3 being covered by the cover 2. Advantageously, the setting means in tension 3 is supported on the ridge element 12 and runs along the latter. In this configuration, the or each elastic strand 3 is able to exert on the cover 2, more particularly on the underside of the latter, normal thrust forces, vertical directed upwards, under the effect of which said cover 2 is tensioning between the two lateral fixing systems 13. Thus the two roof sections 20a, 20b formed by the cover 2 are stretched uniformly between the fixing systems 13 and the tensioning means 3 and offer a devoid appearance folds and other reliefs likely to retain water and dust.

In order to facilitate the positioning and securing of the cover 2 to the fastening systems 13, the tensioning means 3 is able to be maintained in a retracted state according to which no pressure is exerted on the cover. For this purpose the elastic tube 3, constituting the tensioning means is of the inflatable type and is essentially formed by a flexible wall 3a sealed, preferably transparent to light, delimiting at least one sealed internal chamber 30 connected to a source. pressurized gaseous fluid 4 through a supply mouth formed in the wall 3a and a supply line 33 connected to said mouth (Fig.6). A non-return valve 7 will preferably be installed on the supply line 33, at the level of the supply mouth to prevent any reflux of the gaseous inflation fluid from the chamber 30 towards the source of pressurized fluid 4 .

The introduction of the gaseous fluid into the chamber 30 urges the inflatable rod in radial expansion. The advantage of such an arrangement is its simplicity and ease of implementation. In addition, this arrangement gives the strand elasticity properties as well as a latitude of radial expansion thanks to which normal thrust forces will always be applied to the cover regardless of the degree of loosening of the binding.

Preferably, the gaseous fluid used to inflate the tube 3 is air and the source of pressurized fluid 4 is constituted by a fan, for example of the centrifugal type. This fan 4 comprises an electric actuating motor connected to an electric circuit, by the control of which it is possible to introduce on demand into the sealed chamber 30 of the inflatable tube 3, pressurized air. It is therefore understood that the mechanical tension applied to the cover 2 depends on the degree of inflation of the tube and that by controlling the fan 4 it is possible to adjust the degree of this mechanical tension. Another advantage of using an elastic inflatable tube and of keeping the tension of the sheet constant despite a defect in one of the lateral fixing systems 13. In another way it becomes possible to adjust the pressure of gaseous fluid in the chamber 30 of the flange 3 and consequently adjust the mechanical tension of the cover. In addition, it becomes possible in a simple way to compensate for an excessive accidental loosening of the fixing of the cover 2 or an excessive insufficiency of this fixing by introducing into the chamber 30 of the tube 3 an additional quantity of gaseous fluid.

Advantageously, the inflatable tube 3 is equipped with an emptying mouth formed in its wall 3a. This emptying mouth is associated with a solenoid valve 34, of the normally closed type, which can be in the form of a non-return valve piloted pneumatically or electrically during opening.

According to a first embodiment, the inflatable tube 3 is supported on the ridge 12 of the arch structure and runs along the latter. It can simply be placed on the ridge element 12 or else fixed to it.

In order to receive the flange 3 for fixing, the profile constituting the ridge element 12 is provided with a longitudinal groove 120 and receives from place to place, fixing means each comprising a pinching element 121 and a locking key. 122. Each pinching element 121 is formed by a profile of short length of U-shaped cross section provided with two lateral wings and a basal wing. Each locking key 122, formed of an oblong cross section profile is intended to be introduced into the corresponding pinching element 121. The wall of the flange 3a is introduced into the groove 120 and is held there by the nipping elements 121. The locking keys122 introduced into the nipping elements 121 provide the lateral wings of the flange 3a against the wall 3a gripping element 121. The wall 3a is thus blocked between the walls of the groove 120 and the lateral wings of the gripping element 121.

Alternatively, the ridge element 12 is arranged in a cradle, the flange 3 for tensioning the cover being fixed or simply supported in said cradle.

Another embodiment of the tensioning means 3 is shown in FIG. 8. It is noted in this figure that the tensioning means is formed by two inflatable, elastic, parallel tubes separated from one another by a attachment zone 31 continuous elongated intended to cooperate in attachment with the ridge element in the manner previously mentioned. In this embodiment, the chambers 30 of the two tubes are preferably supplied by a single source of pressurized fluid 4. It can be seen in this figure that the tubes 3, by their longitudinal axis are parallel to the axis longitudinal of the ridge element 12. According to a practical embodiment, the tensioning means is formed from a tubular sheath comprising two continuous weld lines 32 delimiting the fixing zone 31.

In Figure 9 is shown another embodiment of the tensioning means 3. As can be seen, this tensioning means 3 is designed to be covered by the cover 2, and is arranged in ridge and run along the ridge element 12. This tensioning means 3 is constituted by arches 35 whose concavity of each is oriented downwards. Each arch 35 course between two consecutive arches 11 of the frame 1 and by its two ends, is supported by the top of these two arches. In addition, the plane containing the central longitudinal geometric axis of each arch is contained in a vertical geometric plane containing the vertices of each arch and the vertex of each arch 35 is located at the midpoint between the two consecutive arches 11 correspondents. .

According to a first embodiment, each arch 35 is formed by conformation of the ridge element 12, while according to a second embodiment, each arch 35 is formed by an arched element, attached to the ridge element 12.

This arrangement of arches 35 makes it possible to reduce the size of the deflection formed by the cover between two consecutive arches, by ensuring, by elevation, a higher tension of said cover, in its median zone, between two consecutive arches. This tensioning means as described can be combined with a tensioning means formed by an inflatable or non-inflatable elastic tube as previously described. In this case, the flange 3 will be carried by the arches 35.

In figurelO is shown a single-tunnel greenhouse but which can be multi-tunnel, provided with a tensioning means 3 in ridge and whose cover 2 always rests on said means 3 and is formed by two flexible walls 21,22 waterproof and airtight, superimposed, lower 21 and upper 22, fixed to one another by their longitudinal and lateral edges, determining in combination with the arch structure, in particular a first roof section 20a , and a second roof panel 20b both extending from the ridge 12 downwards. These two roof sections 20a, 20b are fixed by their horizontal lower edge to the fixing elements 13. Advantageously, these two walls can be formed from a delaminable multilayer film such as that described in patent EP 2 882 586 (PLASTIKA KRITIS) or alternatively by two superimposed films. Note in this figure that the tensioning means 3 is formed by an inflatable tube 3.

As will be understood, each roof section 20a, 20b is formed by a lower wall section 21 and an upper wall section 22. Between the two sides of the walls of each roof section 20a, 20b is formed a chamber waterproof 23a for pan 20a and 23b for pan 20b. These chambers 23a, 23b, are intended to be inflated with a gaseous thermal insulation fluid under pressure, constituted for example by air.

In view of its inflation, each roof section 20a, 20b comprises at least one pressurized fluid supply mouth from its sealed chamber 23a, 23b, said mouth being connected to a dedicated source 4 ′ of pressurized fluid by the through a supply line 24 (Fig. 11). As can be understood from the two roof sections, two 4 ′ sources of pressurized fluid are associated. So the two roof sections can be inflated independently of each other. Alternatively, as can be seen in FIG. 12, the chambers 23a, 23b of the two roof sections are supplied by a pneumatic distribution assembly connected to one and the same source of pressurized fluid, and suitable for the control to simultaneously inflate the two chambers 23a, 23b or only one of these two.

Still according to the preferred embodiment, the source of pressurized fluid 4 ′ for supplying the chamber 23a, 23b of each roofing panel is a fan, for example a centrifugal fan.

Advantageously, a non-return valve 7 is arranged on the supply line of each chamber 23a, 23b to oppose the emptying of said chamber. This non-return valve 7 is preferably fixed to the edge of the supply mouth of the chamber 23a, 23b of the corresponding roof panel.

Under the effect of the radial expansion of the strand constituting the tensioning means 3, the two walls 21, 22 constituting the cover 2 are brought into strong pressure against each other and this according to a contact zone located to the right of said tensioning means 3 and at the ridge, which on the one hand always ensures the tensioning of said walls 21, 22 and therefore of said roof sections 20a, 20b and pneumatically insulates one of the 'other, the two chambers 23a, 23b formed in these two roof sections. It then becomes possible either to inflate the two chambers 23a, 23b and form a double wall system on each of the roof sections 20a, 20b, or to keep the chamber of one of the two roof sections 20a, 20b in a state swollen, and to empty the other chamber of any gaseous thermal insulation fluid or else to empty the two chambers of any gaseous thermal insulation fluid. Usually, the greenhouses are oriented so that one of their roof sections, for example the first panel 20a, is exposed to the west while the other roof panel 20b is exposed to the east.

These provisions therefore give the greenhouse characteristics of transparency and thermal insulation which can be adjusted both to the climatological conditions at the time and to the different periods of the day. Thus in the cold season, for example, the two roof sections 20a, 20b can be inflated at night to slow the cooling of the internal volume of the greenhouse. In addition if the greenhouse is oriented so that one of its two sides, for example the pan 20a is exposed to the west and the other 20b to the east, the arrangements described above allow the internal chamber to be emptied. pan facing east at daybreak so that it is brought back into a single walled roofing configuration. In this way the penetration of infrared radiation into the greenhouse will be favored and the warming of the internal volume of the greenhouse will be accelerated.

It should be noted that in the absence of any gaseous fluid in the chamber of the corresponding roofing panel, the wall sections 20a, 20b of the latter, under the effect of both atmospheric pressure and under the effect of their tensioning are pressed against each other so that this roof panel then adopts a single wall covering configuration. Thus, the thermal insulation characteristics of this roof panel are reduced and its transparency to light and more particularly its transparency to infrared is increased.

Preferably, the sealed chamber 30 of the inflatable tube 3 and the sealed chamber 23a of the first roof panel 20a are arranged pneumatically in series, the two chambers 23a, 30 being supplied with pressurized fluid by the same source of pressurized fluid 4. The advantage of such a configuration lies in particular in the fact that only one source of pressurized fluid is used to supply the tube 3 and the first roof panel 20a, which is a factor in reducing the cost of the greenhouse.

Advantageously, the source 4 of pressurized fluid is disposed immediately upstream of the sealed chamber 23a of said rod 3 so that the condensation of the water vapor transported by the pressurized fluid essentially forms in the chamber 30 of the rod 3. This minimizes the amount of condensation in the sealed chamber of the associated roof pan so that the latter retains good transparency. Alternatively, the chamber 23a of the roof panel 20a and the chamber 30 of the inflatable tube 3 are supplied by their own source of pressurized fluid.

As said previously, the sealed chamber 23b of the second roof panel 20b is supplied with pressurized gaseous fluid, of thermal insulation by a source of pressurized fluid 4 ’which is specific to it. This source of pressurized fluid 4 ′ is formed by a reversible fan actuated by an electric motor known per se. This fan is capable of controlling either supplying pressurized fluid to the sealed chamber 23b of said roof panel 20b to configure the latter into a double wall, or to rapidly extract from this chamber 23b said fluid in order to configure the roof panel 20b in single wall.

Alternatively, the fan is not of the reversible type and one of the two wall sections 21, 22 of the roof panel 20b, preferably the bottom wall panel 21, is provided with at least one associated drainage mouth 25 to a controlled opening and closing means. According to a first embodiment, the opening and closing means is formed by a solenoid valve 8. The activation of the solenoid valve 8, therefore ensures communication between the emptying mouth 25 and the atmosphere. Thus the gaseous fluid present in the chamber 23b can escape to the internal volume of the greenhouse.

According to another embodiment, as shown in Figures 15 to 17, the emptying mouth 25 is formed in the second roof panel 20b at one of the end arches 11 and the opening and closing means controlled is formed by a cable 9 suitable, under the effect of a tensile force applied by an actuator 90, to tighten and apply one against the other the two banks of the emptying mouth 25.

In order to form the emptying mouth, according to a practical embodiment, the upper wall 22 of the cover 2 from its lateral edge at one of the end hoops 11 has two rectilinear cutouts spaced apart from one of the other in order to form a ribbon 22a and the pinching element 115, in line with the ribbon 22a formed, is free from a locking key 116, the lower wall 21 of the cover 2 being always held in fixing in the groove 110 by said element pinch 115. The locking key 116 is therefore formed of two sections of locking key 116 spaced from one another, developing respectively below and beyond the emptying mouth 25. This emptying mouth 25 is therefore formed between the pinching element 115, the strip 22a and the corresponding ends of the two sections of locking key 116. Each of the two sections of locking key 116 has a longitudinal channel passing through it. uel is slidably engaged the cable 9. This cable 9 is fixed by one of its external ends to the key sections 116, to the ridge element 12 and by its other external end to the key sections, to the actuator 90. In addition, the traction cable 9 is engaged on the strip 22a. Thus under the effect of a tensile force applied by the actuator 90, the cable 9 is tensioned and firmly applies the tape 22a against the hoop 11 and more particularly against the pinch profile 115. The emptying mouth 25 is thus closed. On the other hand, when the cable 9 is relaxed, the ribbon 22a, under the effect of the action of the pressure prevailing in the chamber 22b, is moved away from the pinching element 115 which has the effect of opening the mouth of emptying 25.

Advantageously, the actuator 90 is constituted by an electric linear actuator but any other type of motor member capable of exerting mechanical traction on the cable 9 and of releasing this traction can be used. In FIGS. 15 to 17, a hoop 11 having only one groove 110 is shown, but it goes without saying that this hoop 11 may have several grooves 110 as shown in FIGS. 3 and 4.

Preferably, as can be seen in FIGS. 13 and 14, the internal chambers 23a, 23b of the two roof sections are connected to each other by at least one pipe 26 comprising a solenoid valve 8 ’of the normally closed type. The solenoid valve 8 ’in its rest state prohibits any movement of fluid from the chamber 23a of the first roof panel to the chamber 23b of the second. On the other hand, by activating the solenoid valve 8 ’the communication between the two chambers 23a, 23b of the two roof sections is established. The purpose of such an arrangement is to accelerate and facilitate the filling of the chamber 23b by supplying pressurized fluid to the chamber 23a. The solenoid valve 8 ’can be formed by a non-return valve piloted by pneumatic or electric opening.

According to a preferred embodiment, as can be seen in FIGS. 18 to 23, each non-return valve 7 comprises a valve body 70 designed to be fixed in a sealed manner on the one hand to the edge of the supply mouth. corresponding to the element to be supplied with pressurized fluid and, on the other hand, to the supply line for the element to be supplied with pressurized fluid. This valve body 70 includes a through bore 71 or channel, intended to be in communication relationship both with the supply line and with the chamber of the element to be supplied with pressurized fluid. Preferably, this through bore 71 is formed for the most part in the form of a sleeve 71a presented by the valve body 70. This form of sleeve 71a is designed to be fitted into the supply line. The valve 7 further comprises a seat 72, formed in the valve body 70 at one end of the track 71 and a sealed shutter 73, shutter, biased towards the seat 72, that is to say towards a closed position under the effect of the action of the pressure prevailing in the corresponding chamber.

Advantageously, the flap 73 is formed by a flexible membrane provided with a leakage indicator element 73a. This indicator element 73a is formed by a tail, in the form of flexible tape, in the radial extension of the flap 73. This indicator element 73a is capable of hiding in the presence of a leakage air flow. Such an arrangement, when the element supplied with pressurized fluid is formed of a wall transparent to light makes it possible to quickly detect a leak of gaseous fluid.

Still according to the preferred embodiment, the valve body 70 is provided with a base 74 provided on the one hand for being introduced into the chamber of the element to be supplied and on the other hand for being applied in a sealed manner against the face. internal to said chamber, from the wall of said element, the valve 7 is provided with a removable base 75, provided with a through hole in its center, intended on the one hand to be engaged, by this hole, in the form of sleeve 71a and on the other hand be screwed onto the valve body by interlocking forms and be applied in a sealed manner by screwing movement, against the wall of said element to be supplied with pressurized fluids.

Advantageously, the base 74 is equipped with a Vee cut 74a. This cut 74a, by passing through a slot made radially in the wall of the element, from the edge of the corresponding supply mouth, makes it possible to introduce into the chamber of said element, the base 74 which the valve body 70.

According to a practical embodiment, the solenoid valve 8 is formed by a non-return valve 7 as previously described, and by an actuator 80 fixed to the removable base 75. The non-return valve 7 is fixed to the edge of the mouth 25 and opposes the emptying of the chamber 23b of the roof pan 20b. The actuator 80 is capable of actuating in the direction of opening the non-return valve 7 and more particularly the shutter 73 that the latter comprises. The actuator 80 is essentially formed by an electromagnet and is fixed by the carcass 800 of the electromagnet to the removable base 75. The movable core that the electromagnet 80 comprises receives in fixing a rigid pusher 81 for actuating the flap 73 of the non-return valve. This rigid pusher 81 extends axially the mobile core of the electromagnet and is engaged in a through hole formed in the removable base 75 of the valve 7. In addition, when the actuator is activated, the rigid pusher 81 s' engages in a through hole made in the first base 74 to come to act in thrust on the sealed flap 73. Under the effect of the action of the pusher 81, the flap 73 is moved to an open position. In this position the flap 73 is angularly separated from the seat 72 and the gaseous fluid contained in the chamber 23b can escape from the latter. Advantageously, the through bore that comprises the base 74 for the passage of the pusher 81 is formed by the V-shaped cutout that the latter comprises.

Still according to the practical embodiment, the solenoid valve 8 'is formed by a non-return valve 7' and by an actuator 80 'of the electromagnet type, such a solenoid valve preferably being identical to that previously described. Thus the non-return valve 7 ’is identical to the valve 7 and the actuator 80’ is identical to the actuator 80.

We have just described a cover 2 provided with two roof sections inflatable with pressurized air in order to keep the walls 21 and 22 at a distance from each other. Alternatively, as can be seen in FIG. 27, the two walls 21 and 22 of each roof panel 20a, 20b are kept apart from one another by at least one internal tensioning means 3, introduced into the interval between these and developing parallel to the ridge line. Preferably this or each tensioning means 3 is formed by an inflatable elastic tube, arranged parallel to the ridge line, supplied by a source of pressurized air.

In addition to keeping them at a distance, the or each flange 3 ensures the tensioning of the two walls 21, 22 and consequently the tensioning of at least the corresponding roof panel 20a, 20b. In this configuration, the two roof sections 20a, 20b can be separated from each other by a longitudinal junction zone intended to be disposed at right angles and above the ridge element 12. This junction zone may be delimited by one or more continuous lines of weld connecting the two walls 21,22 to each other. This junction zone will therefore ensure a sealed separation between the chambers 23a and 23b of the two roof sections. At least chamber 23b of the second roof panel will be connected to the atmosphere by an appropriate vent opening.

Under the combined effects of the deflation of the or each tube associated with the chamber 23b of the second roof panel 20b, and the tension exerted on the cover 2 by the or each other means of tensioning, the walls 21, 22 of the second roof pan, will be brought against each other which will give said pan a single wall configuration.

In Figure 28 is shown a greenhouse with cover 2 formed of two flexible walls 21 and 22, superimposed, lower 21 and upper 22, fixed to each other by their longitudinal edges, forming in combination with each other a first roof section 20a and a second roof section 20b both extending from the ridge 12, the said roof sections 20a, 20b each always being formed from a bottom wall section and an upper wall section . The walls 21 and 22 forming the cover, always form a housing in which is disposed an internal tensioning means 3 formed by an inflatable tube. According to this embodiment, the inflatable tube is arranged in line with the ridge element 12 parallel to the latter. It can be seen that the two walls 21, 22 are all fixed to the two fixing elements 13 and that the tensioning means is held in place in line with the ridge element 12 by elongated lateral links fixed on the one hand said tensioning means 3 and secondly to the fixing elements 13. Each lateral link may be constituted by a strap or by an elastic element.

These arrangements of tensioning means arranged between the two walls 21, 22 of the cover 2, have the advantage over an arrangement with an inflatable panel to significantly reduce the mechanical stresses exerted on the frame by the cover.

Another advantage is due to the fact that the two walls 21, 22 of the cover 2 do not need to be airtight, which allows the evacuation of the condensation which could form on their internal face at the volume that 'they determine.

We have just described a cover 2 formed by two walls 21, 22 between which is mounted a tensioning means 3 in the form of an inflatable tube, but provision may be made for a cover formed by three or more superimposed walls between which will be disposed. inflatable tubes.

In FIG. 29 are shown a greenhouse cover 2 according to another embodiment incorporating at least one tensioning means 3.

It can be seen in this figure that the greenhouse cover 2 is formed by two cover sections 20a, 20b separated from each other by at least one inflatable tube 3 forming tensioning means, this inflatable tube 3 being fixed by welding to the two sides of the cover.

The or each inflatable tube 3 can be formed by affixing a waterproof strip on the cover and fixing this strip by welds along its longitudinal edges.

Alternatively, FIG. 30, the tensioning means in the form of an inflatable tube and the two covering sections 20a, 20b are formed in a flexible wall made up of two superimposed sheets linked to one another by at least two lines of continuous welds, distant from each other. The inflatable tube 3 is then formed between these two continuous lines of welds. Thus the cover 2 of the greenhouse may have, along its longitudinal median axis, a first zone forming at least one inflatable tube 3, intended to be affixed to the ridge 12 of the corresponding arch structure, and on either side of this first zone, two lateral zones forming the two inflatable sections of roof 20a, 20b. The two lower and upper walls 21, 22 of each of these two roof sections 20a, 20b may be kept apart from one another by pressurized air introduced into the sealed chamber that they determine.

Alternatively, the walls 21, 22 can be kept apart from one another by at least one tensioning means preferably formed by at least one inflatable tube supplied with pressurized air by a source of pressurized air. According to a practical embodiment, two inflatable tubes 3 will be provided, preferably supplied by a single source of pressurized air, spaced from each other and parallel to the median longitudinal axis of the cover so as to be parallel to the ridge line. This cover 2 can be produced from a delaminable multilayer film such as that marketed by Ste PLASTICA KRITIS.

As can be seen in FIGS. 1, 31 and 33, the gutters 6 that the greenhouse comprises are each formed by an inflatable elastic tube, the latter comprising a sealed chamber 60 designed to receive a gaseous fluid under pressure, for example from the air. To this end, this chamber is connected by a supply line 61 to a source of pressurized fluid 62 known per se. On the pipe 61 is preferably installed a non-return valve 7 of the type of that previously described. The strand constituting the gutter 6 comprises a drain mouth associated with a solenoid valve 8 of the type of that previously described.

Such an arrangement of inflatable and deflatable elastic tube 6 is particularly suitable for multi-tunnel greenhouses, the tubes 6 facing each other coming into pressure against each other under the effect of their inflation to form at least a rainwater drainage channel. Thanks to their radial elasticity, the gutters can deform under the effect of external mechanical stresses and resume their shape as soon as these stresses cease. Thus in the event of a heavy accumulation of snow or hail, for example, the strands constituting the gutters 6, under the effect of the weight of the precipitation, may deform radially, to release openings through which the precipitation may flow by gravity towards floor.

Another advantage of such a configuration lies in the fact that by deflating the tubes 6, longitudinal ventilation openings are created, lateral to each tunnel, the banks of which are formed by the corresponding fixing elements 13. More precisely, each ventilation opening is bordered by the fastening systems 13 of the two corresponding consecutive tunnels. Thus the flanges 6, in addition to a gutter function, fulfill the function of elements for closing the opening of aeration. Advantageously, so as to increase the size of the ventilation opening, the support posts 10 are inclined towards the longitudinal median plane of the corresponding tunnel.

The two inflatable tubes 6 of each tunnel may be of the same height and occupy identical height levels, as can be seen in FIG. 1, but preferably, as can be seen in FIG. 32, one of the inflatable tubes 6 of each tunnel is of a diameter greater than the other inflatable tube of this same tunnel, the inflatable tube 6 of larger diameter occupying a level of height greater than that occupied by the other tube 6. Thus each ventilation opening is closed by a large diameter rod and by a smaller diameter rod. The flange 6 of larger diameter when inflated is supported not only on the cover 2 of the tunnel to which it is fixed but also on the cover 2 of the tunnel opposite. This sausage 6 of larger diameter also bears on the sausage 6 of smaller diameter when the latter is inflated, this second sausage 6 occupying a lower height level and taking support when it is inflated on the framework of one and the other tunnels. Such an arrangement is such as to facilitate the conduct of the runoff water towards the ends of the two gutters 6 formed by these tubes. More precisely, this configuration allows the creation of a form of trough between the tube 6 of large diameter and the cover of the tunnel to which it is fixed and the creation of a form of trough between the tube 6 of small diameter and the cover of the tunnel to which this flange 6 is fixed. These provisions also authorize, by radial deformation of the flanges 6, the evacuation towards the ground of the excess weight of snow or hail.

Advantageously, these tubes 6 are fixed to the corresponding fixing systems 13 and for this purpose the rigid section 130 of each system has a second longitudinal groove 130a in which is engaged the wall of the corresponding tube 6 to be held there by a pinching element 131 U-shaped cross section equipped with a locking key 132 as previously described.

It is necessary to avoid that in the deflated state, the tubes 6, according to the two embodiments previously described, do not each form under the effect of their weight a vertical curtain extending downward so as to oppose good ventilation of the greenhouse. For this reason, each strand 6 is surrounded along its entire length, by an elastic restraining element 63. This elastic restraining element 63 will be fixed from place to place by supports adapted to the fixing element 13 supporting the strand.

To prevent predatory insects from entering the volume of the greenhouse through the ventilation openings, an anti-insect net 65 is associated with each of these latter. As can be seen in FIG. 35, this anti-insect net 65 is suspended by two of its edges opposite the two longitudinal banks of the opening. More specifically, the anti-insect net is fixed to the two fixing systems 13 forming the banks of the opening and more particularly to the sections 130. For this purpose, each section 130 is equipped with a third groove 130a to receive the fixing in place. thread 65. This thread as described above is fixed in the groove 130a by a pinching profile 131 of U-shaped cross section and by a locking key 132 inserted in tightening in the pinching profile 131.

Under the ventilation opening may be arranged a chute 67 for collecting rainwater. Preferably, this recovery chute 67 will be formed in the insect-proof net, in the bottom zone of the latter. This chute 67 may be formed by a strip of waterproof plastic material affixed and fixed against the net or else by a coating formed in the net using a waterproof resin.

The sealed chamber 60 of each inflatable tube 6 is supplied with gaseous pressurized fluid by a source of pressurized fluid which may be constituted by the fan 4 or by an additional fan.

In Figure 37 and 38 is shown a greenhouse comprising at least one lateral ventilation system according to another embodiment, suitable, when it is actuated to close or clear a lateral ventilation opening of said greenhouse. It can be seen in this figure that the horizontal longitudinal lower edge of the ventilation opening is formed by a rigid gutter, in the form of a gutter and more particularly by the upper edge of the corresponding lateral flank of this gutter 6. The upper longitudinal edge horizontal of the ventilation opening is formed by the corresponding fixing system 13 and more particularly by the section 130 of this fixing system. The cover 2 of the greenhouse rests on a tensioning means formed by an inflatable tube 3 disposed at the ridge. According to this embodiment, the horizontal upper edge 13 is movable between a position of occlusion of the lateral opening, according to which it is in leaktight contact with the gutter 6 and a position of release from said opening according to which it is separated in height by the lower longitudinal edge, that is to say of the gutter 6, said horizontal upper edge 13 being driven between the two aforementioned positions by the inflatable tube 3 and by a traction means integral with the gutter 6 and the movable upper edge 13 More specifically, this movable edge or fixing system 13 is driven from the occlusion position, towards the open position by the inflatable tube 3 and more particularly by the radial expansion of the latter, and is driven from the opening position to the occlusion position by the traction means. Thanks to the previously described provisions, it becomes possible to adjust the size of the opening and consequently the degree of ventilation of the internal volume of the greenhouse.

The mobile fixing system 13 is guided along the arches 11 which carry it by carriages 14. As can be seen, each carriage 14 is fixed to the profile 130 of the fixing system 13 and comprises several rollers 141 which grip the hoop 11 correspondent. More specifically, each carriage 14 has a carriage body 140, forming a yoke, coming around the arch and two pairs of rollers 141, namely an upper pair and a lower pair both coming into contact with the arch 11 in order to be able to ride on the latter.

According to a practical embodiment, the traction means is formed by a winding shaft 15, held in the gutter 6 and by straps or the like fixed on the one hand to the fixing element 13 and on the other to the winding shaft. The winding shaft 15 is held in place in the gutter by stirrups 68 in the form of an inverted U each having two parallel lateral branches and a basal branch joined to the two lateral branches. These stirrups 68 are arranged vertically in the gutter 6, overlapping the winding shaft 15 and are fixed to said gutter 6 by the free ends of their lateral branches.

In order to release the lateral opening, the winding shaft 15 is actuated in the direction of the unwinding of the straps 16 and the upper edge of the opening, namely the fastening element 13 is driven upwardly. of the radial expansion of the inflatable tube 3. On the other hand, in order to close the lateral opening, the winding shaft 15 is actuated in the direction of winding of the straps 16 and a tensile force is exerted on the fastening system 13 and on the cover 2. Under the effect of the tensile force collected by the cover 2, the tensioning means 3 is caused to deform radially in an elastic manner and then constitutes an elastic member of reminder suitable for radial expansion, to drive the fixing system 13 upwards during the unwinding of the straps.

Alternatively, the straps 16 are replaced by an anti-insect net. This anti-insect net will be breathable to provide ventilation but will have mesh fine enough to prevent the introduction of insects into the volume of the greenhouse.

Preferably, each roof panel by the cover 2 rests on at least one support element 28 arched substantially in the shape of a U, fixed by its two ends to a horizontal rigid element that the frame carries or comprises, the support element being parallel said roof panel and being supported by its summit zone on one of the arches of the frame.

Each arched, tubular support element 28 is advantageously made of synthetic material, typically of so-called plastic material. In this way, the weight of the element is reduced. Each roof section is supported between two consecutive arches by at least two support elements 28.

Preferably, the concavity formed by each support element 28 is oriented downwards towards the corresponding gutter and said element 28 is fixed by its two ends either to the gutter, the latter then being rigid and in the form of a gutter, or to the fixing element 13. With a view to this fixing, embedding rods are fixed either to the gutter or to element 13. The tubular supports 28 are fitted at their ends onto said embedding rods.

Still according to the preferred embodiment, each support element 28 is dimensioned so that by its summit zone it is situated approximately halfway between the ridge element 12 and the gutter 6. As can be seen the two ends of this support element 28 are located respectively on either side of the arch considered at equal distance from the latter.

Advantageously, each support element 28 comprises a groove 280 for draining the condensation water disposed opposite the roof panel, one of the two lips of said groove 280 being in contact with the cover of the roof panel. This groove 280 is in communication relation with the corresponding channel 6 to conduct the condensation water which it collects. Diametrically opposite the groove 280, each support element 28 has a flat support surface 281. By this planar face 281, the support element 28 is supported on the corresponding hoop 11. Such a support element 28 can be produced from the tubular profile as described in patent FR 2 988 710 of the applicant.

To further strengthen the support action, one or more support elements 28 may be placed in the intervals formed between the arches 11.

It goes without saying that the present invention can receive all arrangements and variants in the field of technical equivalents without departing from the scope of this patent as defined by the claims below.

Claims (34)

claims 1 / Greenhouse for the cultivation of food crops, comprising a metal supporting framework (1) forming an arch structure at least in the upper part, formed of successive parallel arches, which arch structure is carried by poles (10) anchored to the ground , has a ridge element (12) and is completely covered by a flexible cover (2) having two large opposite faces, one of which, lower, faces the internal volume of the greenhouse and the other, upper, faces towards the exterior of said volume, said cover (2) determining in combination with the arch structure, two roof sections (20a, 20b) extending from the ridge element (12) downwards, which sections are fixed by their lower horizontal border with two lateral fixing systems (13) which comprises the framework (1) on either side of the arch structure, gutters (6) for evacuating rainwater being available attached to the frame on either side of said arch structure, characterized by a means of tensioning the cover (2), independent of the two fixing systems (13), which are arranged at a distance from said means of tensioning (3) of the cover (2). 2 / Greenhouse according to the preceding claim, characterized in that the tensioning means (3) is configured capable of occupying, when ordered, a retracted state according to which it exerts no tensioning force on the cover ( 2) and a deployed state in which it exerts forces on said cover so that the latter is kept in tension between the two fixing systems (13), the forces applied to the cover (2) being distributed along at least one parallel line at the ridge. 3 / Greenhouse according to the preceding claim, characterized in that the or each tensioning means (3), at least in its deployed state, forms extra thickness on the arch structure. 4 / Greenhouse according to any one of the preceding claims, characterized in that the or each tensioning means (3) acts on one at least large face of the cover (2) and exerts on said large face of the forces normal thrust and or traction. 5 / Greenhouse according to any one of the preceding claims, characterized in that the or each tensioning means (3) is parallel to the ridge. 6 / Greenhouse according to any one of the preceding claims, characterized in that the or at least one of the tensioning means (3) runs along the ridge (12) of the arch structure and is fixed to the latter. 7 / Greenhouse according to the preceding claim, characterized in that the ridge (12) is arranged in fixing profile, the tensioning means (3) being fixed to said profile (12). 8 / greenhouse according to any one of the preceding claims, characterized in that the or each tensioning means (3) is arranged under the cover (2). 9 / Greenhouse according to claim 5, characterized in that at least one tensioning means (3) is integrated in the cover (2). 10 / Greenhouse according to any one of the preceding claims, characterized in that the or each tensioning means (3) is constituted by at least one elastic rod, of elongated shape, radially expandable, disposed in contact with the cover ( 2). 11 / Greenhouse according to the preceding claim, characterized in that the or each tube (3) comprises at least one sealed internal chamber (30) and receives in said chamber (30) a gaseous fluid under pressure which urges it in radial expansion, said gaseous fluid being supplied by a source (4) of gaseous fluid connected to said chamber (30) by a supply line (33) on which a non-return valve (7) is installed. 12 / Greenhouse according to the preceding claim, characterized in that the tensioning means (3) consists of two inflatable tubes, parallel, separated from each other by a longitudinal zone of attachment to the ridge element (12). 13 / Greenhouse according to any one of the preceding claims, characterized in that the or one of the tensioning means (3) is covered by the cover (2) and consists of arches (35) whose concavity of each is oriented downwards, said arches (35) being formed in ridge, each between two arches (11) of the arch structure. 14 / Greenhouse according to claim 11 taken in its attachment to claim 9, characterized in that the cover (2) is formed of a single flexible wall, the or each tensioning means (3) being constituted by a flange inflatable formed by a sealed channel formed in said cover (2). 15 / Greenhouse according to claim 11 taken in its attachment to claim 9, characterized in that the cover (2) is formed of two flexible walls (21,22) superimposed, lower (21) and upper (22), fixed l '' to each other by their longitudinal and lateral edges, forming in combination with the arch structure a first roofing section (20a) and a second roofing section (20b) both extending from the ridge (12) towards the bottom, said roof sections (20a, 20b) each being formed by a lower wall section and an upper wall section and each forming between the lower and upper wall sections, a housing in which is disposed at least a means for tensioning (3) the cover (2), constituted by an elastic inflatable tube extending parallel to the ridge line. 16 / Greenhouse according to claim 11 taken in its attachment to claim 9, characterized in that the cover (2) is formed by two flexible walls (21,22) superimposed, lower (21) and upper (22), fixed l '' to each other by their longitudinal and lateral edges, forming in combination with the arch structure a first roofing section (20a) and a second roofing section (20b) both extending from the ridge (12) towards the bottom, that the two flexible walls (21,22) form a housing in which is disposed a tensioning means (3) constituted by an elastic inflatable tube, that the inflatable tube (3) is arranged in line with the ridge element (12) parallel to the latter and that the tensioning means (3) is held in place in line with the ridge element (12) by elongated lateral links fixed on the one hand to said setting means in tension (3) and on the other hand to the fixing elements (13). 17 / greenhouse according to any one of claims 1 to 13, characterized in that the cover (2) is formed by two flexible walls (21, 22) waterproof and airtight, superimposed, lower (21 ) and upper (22), fixed to each other by their longitudinal and lateral edges, forming in combination with the roof structure a first roofing section (20a) and a second roofing section (20b) extending both from the ridge (12) downwards, said roof sections (20a, 20b) each being formed by a bottom wall section and an upper wall section and each forming between the lower and upper wall sections , a sealed chamber (23a, 23b) intended to be inflated with a gaseous thermal insulation fluid, under pressure, said roof sections (20a, 20b) being fixed by their horizontal lower edge to the fixing elements (13) and comprising each at least one fluid supply mouth under pressure from their sealed chamber (23a, 23b), said mouth being connected to a source of pressurized fluid (4, 5) by means of a non-return valve (7) and a supply line (24 ). 18 / greenhouse according to claims 11 and 17 taken together, characterized in that the sealed chamber (30) of the inflatable tube (3) and the sealed chamber (23a) of the first roof section (20a) are arranged pneumatically in series, the two chambers (23a) and (30) being supplied with pressurized fluid by the same source of pressurized fluid (4) which is disposed immediately upstream of the sealed chamber (30) of said tube (3). 19 / Greenhouse according to claim 17 or claim 18, characterized in that the sealed chamber (23b) of the second roof panel (20b) is supplied with pressurized gaseous fluid, of thermal insulation, by a source of pressurized fluid (4 ') which is specific to it, each supply mouth being connected by a line (24) to the source of pressurized fluid (4'). 20 / Greenhouse according to any one of claims 17 to 19, characterized in that one of the two sides of the walls forming the second roof panel (20b) is provided with at least one through emptying mouth (25) associated in a sealed manner to a solenoid valve (8) of the normally closed type, the activation of said solenoid valve ensuring communication between the through mouth and the atmosphere. 21 / Greenhouse according to any one of claims 17 to 20, characterized in that the second roof panel (20b) is provided with an emptying mouth (25) associated with a controlled opening and closing means and that said emptying mouth is made in the second roof panel (20b) at one of the end arches (11) and that the controlled opening and closing means is formed by a suitable cable (9), under the 'effect of a tensile force, to tighten and apply one against the other the two banks of the emptying mouth (25). 22 / Greenhouse according to the preceding claim, characterized in that the outermost groove (110) of each end arch of the or each vault receives the cover (2) in fixation, that this cover is introduced into the groove ( 110) and is blocked there by a pinching element (115) provided with two parallel lateral wings maintained in pressure against the cover by at least one locking key (116) of oblong cross section, introduced in clamping between the wings of the nipping element (115), that the upper wall (22) of the cover (2) from its lateral edge at the level of the end arches has two rectilinear cutouts spaced apart from one another in order to form a ribbon (22a), that the pinching element (115) in line with the ribbon (22a) is free from a locking key (116), that the locking key (116) is formed by two sections of locking key spaced apart. one from the other, developing respectively in de here and beyond the emptying mouth thus formed, that each section of locking key (116) is provided with a longitudinal through channel in which the cable (9) is slidably engaged, and that this cable (9) is engaged on the ribbon (22a) and is fixed by one of its external ends to the key sections, to the ridge element (12) and by its other end external to the key sections (116), to an actuator (90). 23 / greenhouse according to any one of claims 17 to 22, characterized in that the internal chambers (23a, 23b) of the two roof sections (20a, 20b) are connected to each other by at least one pipe (26) comprising a solenoid valve (8 ') of the normally closed type. 24 / Greenhouse according to claims 11 or 17, characterized in that each non-return valve (7) comprises a valve body (70) comprising a through bore (71) or track, a seat (72) at one of the ends of the track and a sealed shutter (73), and urged towards the seat (72), that is to say towards a closed position under the effect of the pressure and that the flap (73) is formed by a flexible membrane provided with a leak indicator element (73a). 25 / Greenhouse according to the preceding claim, characterized in that the leak indicator element (73a) is formed by a flexible strip capable of baking in the presence of a leakage air stream. 26 / Greenhouse according to any one of the preceding claims, of the multi-tunnel type, each tunnel of which comprises two lateral gutters (6), characterized in that the gutters (6) of each tunnel are each formed by an inflatable tube, the latter comprising a sealed chamber intended to receive a gaseous fluid under pressure and the inflatable tubes (6) facing two consecutive tunnels coming into pressure against each other under the effect of their inflation to form at least one water flow channel, said two tubes (6) of one and the other tunnel, by deflation, releasing an air opening. 27 / greenhouse according to the preceding claim, characterized in that under each ventilation opening is disposed an insect-proof net (65), said net being suspended from the two longitudinal banks of the opening. 28 / Greenhouse according to the preceding claim, characterized in that under each opening is arranged a chute (67) for recovering rainwater. 29 / Greenhouse according to the preceding claim, characterized in that the chute (67) is formed in the anti-insect net (65). 30 / Greenhouse according to any one of claims 26 to 29, characterized in that one of the inflatable tubes (6) of each tunnel is of a diameter greater than the other inflatable tube (6) of this same tunnel, the larger diameter inflatable tube occupying a higher level of height than that occupied by the other tube. 31 / Greenhouse according to any one of claims 26 to 30, characterized in that each strand (6) is surrounded along its entire length by an elastic retaining element (63). 32 / Greenhouse according to any one of claims 10 to 12, characterized in that it comprises a tensioning means formed by at least one inflatable tube (3) disposed in ridge and covered by the cover (2) and at less a lateral ventilation opening closed or cleared by action on a lateral ventilation system, than the lower longitudinal horizontal edge of the ventilation opening is formed by a rigid gutter (6), in the form of a gutter, than the horizontal longitudinal upper edge of the opening is formed by the fixing system (13) to which the lower edge of the greenhouse cover (2) is fixed, that the horizontal upper edge (13) is movable between an occlusion position of the lateral opening, according to which it is in leaktight contact with the gutter (6) and a position for releasing the opening according to which it is spaced apart in height from the lower longitudinal edge eure, said horizontal upper edge (13) being driven between the two aforementioned positions by the inflatable tube (3) and by a traction means secured to the gutter (6) and the movable upper edge (13). 33 / Greenhouse according to any one of the preceding claims, characterized in that each roof panel by the cover (2) rests on at least one arched support element (28) substantially in the shape of a U, fixed by its two ends to the gutter ( 6) corresponding, the support element (28) being parallel to said roof panel and resting by its summit zone on one of the arches (11) of the frame (1). 34 / Greenhouse according to the preceding claim, characterized in that the concavity formed by the support element (28) is oriented downwards, towards the corresponding gutter (6) and that said element (28) has a groove (280) of drainage of the condensation water placed opposite the roof panel, one of the two lips of said groove being in contact with the cover (2) of the roof panel and said groove (280) being in communication relation with the corresponding channel (6).