Greenhouse

Greenhouse comprised of a ridge beam extending some distance above its roof defining two elongated side zones at either side of the ridge beam. The ridge beam is comprised of one or more elongated hollow spaces and with one or more closable openings in both side zones. The openings fluidly connect the exterior of the greenhouse with its interior and may be closed at one side and opened at its other side depending on the direction of the wind.

This application is a national stage entry of International Patent Application No. PCT/NL2018/050876, filed Dec. 21, 2018, which is incorporated by reference in its entirety.

This application claims priority to Netherlands Patent Application No. 2020176, filed Dec. 22, 2017, which is incorporated by reference in its entirety.

BACKGROUND

The invention is directed to a greenhouse comprised of transparent walls and a structure comprising of one or more ridge beams as part of a roof of the greenhouse. The invention is also directed to a novel ridge beam. The invention is also directed to a method to condition the air within a greenhouse.

DE8426219 describes a building with a ventilating ridge beam. The beam construction is provide with two elongated flaps which can simultaneously open and close thereby providing a ventilation opening.

DE1454648 describes a greenhouse provided with a window near the ridge beam allowing air to escape the greenhouse.

Such a greenhouse is described in WO17176114. InFIGS.1and2a schematic representation of a greenhouse with a saddle roof is shown. In the roof ventilating windows are present to discharge excess air from the interior of the greenhouse to the exterior of the greenhouse. Such ventilating windows are typically present in every saddle roof at a regular interval. A disadvantage of such ventilating windows is that the frames and controls to operate the window take away light and thus negatively affect the efficiency of the greenhouse to grow plants. Furthermore, local pressure differences and temperature differences may result from the internal gas flows towards these windows.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a greenhouse which has a higher efficiency of the available sun light and avoids the local pressure differences and temperature differences.

This is achieved by the following greenhouse. Greenhouse comprised of transparent walls and a structure comprising of one or more ridge beams as part of a roof of the greenhouse,

wherein the ridge beam extends some distance above the roof defining two elongated side zones present above the roof and at either side of the ridge beam,

wherein the ridge beam is comprised of one or more elongated hollow spaces,

wherein the ridge beam is provided with one or more closable openings in both side zones which openings fluidly connect the exterior of the greenhouse with the one or more elongated hollow spaces of the ridge beam, and

wherein the ridge beam is provided with one or more openings at its lower end fluidly connecting the interior of the greenhouse with the one or more elongated hollow spaces of the ridge beam.

The greenhouse according to the invention will have less light blocking parts near the roof of the greenhouse than the prior art greenhouse. Furthermore, a more even discharge of air from within the greenhouse to its exterior via the roof is possible. This will decrease the local pressure and temperature differences within the greenhouse. Further advantages will be discussed when describing the preferred embodiments of the invention.

The ridge beam may suitable be provided with an elongated valve to direct air from within the greenhouse to one side of the ridge beam. This is advantageous because the operator or computer operating the greenhouse can open de openings in the ridge beam at the leeward side or windward side in case a wind is blowing over the greenhouse. Openings at the leeward side is preferred when air is to be discharged from the greenhouse to its exterior and openings at the windward side is preferred when air is to enter the greenhouse from its exterior. Preferably the openings in the ridge beam are used to discharge air from the greenhouse to its exterior. In a prior art greenhouse the ventilating windows are typically positioned at the leeward side of a roof for the locally most predominant wind direction. The greenhouse according to this invention enables one to discharge air via a leeward opening independent of the wind direction. In a prior art greenhouse the ventilating windows would have to be shut when the wind blow from the wrong direction at a certain high wind speed. By wrong direction is here for example meant that the wind blows into the openings of the ventilating windows. This mandatory closing of the windows is not preferred because it limits the possibilities for conditioning the air within the greenhouse. In the greenhouse having the ridge beam as here described such safety shutting of the ventilation openings is not required because one can always use the openings in the ridge beam at its leeward side.

The valve has at least a first position wherein the one or more openings in a first elongated side zone fluidly connect the exterior of the greenhouse with the one or more elongated hollow spaces of the ridge beam and wherein the one or more openings in the opposite and second elongated side zone are closed, a second position wherein the one or more openings in the second elongated side zone fluidly connect the exterior of the greenhouse with the one or more elongated hollow spaces of the ridge beam and wherein the one or more openings in the first elongated side zone are closed. By closed is here also meant substantially closed. There may be gas passages from the hollow space of the ridge beam to the closed openings as illustrated inFIGS.1,2,9and10by which a very small amount of air may pass towards the exterior of the greenhouse. Such small volumes of air are however considered insignificant for the working of the ridge beam.

Preferably the valve has a third position which results in that the interior of the greenhouse is not fluidly connected to the exterior of the greenhouse via the openings of the ridge beam. This may be by enclosing the openings in the two elongated side zones and/or by enclosing the one or more openings at its lower end of the ridge beam. Preferably the valve has intermediate positions wherein the size of the one or more opening in one of the two elongated side zones and/or the size of the opening at the lower end of the ridge beam can be varied while the one or more openings of the other elongated side zone are closed. This is advantageous because one can then fully close the greenhouse and control the volume of air being discharged from the interior of the greenhouse to its exterior.

The valve may be one or more screens which can move in the elongated direction of the ridge beam and close or open the openings at either of the elongated size zones depending on its position relative to the two elongated zones. For example the openings in the two elongated zones may be openings in an upwardly extending wall which is covered by an elongated and moveable top having at either elongated side a downwardly directed screen also provided with openings. The screen may run within the two upwardly extending walls or preferably outside the two upwardly extending walls. The openings in the screen may or may not align with the openings in the upwardly extending walls depending on the position of the moveable top. The openings may be alternatingly positioned in the two screens when viewed along the length of the screens or alternatingly positioned in the upwardly extending walls when viewed along the length of the walls. The top may be moved by well known techniques.

Instead of the top with screens the longitudinal moveable valve may also be a tube placed within a hollow space of the ridge beam having a tubular shape. The tubular valve is then co-axially moveable within this tubular hollow space.

The valve preferably changes from one position to another position by rotation along an axis running parallel with the ridge beam. The valve may also rotate along more than one axis running parallel with the ridge beam. The valve is suitably connected to a means to rotate the valve in case the valve changes position by rotation along one axis. Such a means may be a tubular motor. The valve is suitable rotatably connected to a motor positioned below the ridge beam via a transmission, for example a bevel gear. Although this motor may block some light it is not as much as would be by the prior art means to open and close the ventilating windows. The valve is suitably connected to a means to tilt the valve in case the valve changes position by rotation along more than one parallel axis.

The valve may have any design which makes it suitable to achieve one or more of the above described positions. In one preferred design the hollow space of the ridge beam has a tubular shape and wherein the valve is rotatably positioned within this tubular hollow space. Suitably this valve is a tube provided with two parallel rows of openings. The tube further has an elongated surface separating the inner tubular space of the valve into an elongated space fluidly connected to the two rows of openings and a remaining space. This remaining is suitably an elongated enclosed space defined by the elongated surface and part of the tubular wall. In order to avoid that the tube-shaped valve gets jammed within the tubular hollow space sliding surfaces are preferably provided. Such surfaces may be part of the stationary ridge beam or part of the rotating valve. Such surfaces may for example be made of messing, Teflon or engineering plastics such as polyamide, for example Nylon. The ridge beam and the tubular shaped valve may be made of aluminium, steel or alloys comprising these metals.

In another preferred embodiment the valve is an elongated rotating cap valve as here described. The upper end part of the ridge beam is an elongated cap valve which can rotate along an axis running parallel with the ridge beam and which axis runs within the hollow space of the ridge beam. The cap valve is shaped such that

in a first rotatable position one or more openings in the first elongated side zone are present which fluidly connect the exterior of the greenhouse with the elongated hollow space of the ridge beam and wherein the second elongated side zone is closed by the cap valve and

in a second rotatable position one or more openings in the second elongated side zone are present which fluidly connect the exterior of the greenhouse with the elongated hollow space of the ridge beam and wherein the first elongated side zone is closed by the cap valve.

In another preferred embodiment the valve is comprised of a first wall part as one elongated side zone and a second wall part as the opposite elongated side zone, wherein the wall parts are rotatably connected to the fixed part of the ridge beam at their lower ends. The wall parts are further both rotatably connected to an elongated bridging part at their upper ends. The axis of rotation of all four rotatable connections run parallel with the elongated ridge beam. This structure enables that the bridging part can tilt in different positions, wherein in at least one position the bridging part closed the openings in one wall part and provides a fluid connection between the exterior of the greenhouse and the hollow spaces via the openings of the other wall part, and wherein in at least another position the bridging part closes the openings of first and second wall part.

The area of openings in the ridge beam per axial length of the ridge beam is preferably between 0.01 and 0.1 m2/m and more preferably between 0.01 and 0.04 m2/m. The ridge beam is suitably not a wide construction. The external width is preferably below 0.11 m. such to avoid that the ridge beam itself blocks too much sunlight. The openings are here defined as the maximum allowable opening. Thus expressly not the sum of open and closed openings.

The ridge beam running along the length of the roof of a greenhouse may be provided in sections, wherein each section is provided with a valve which can be independently operated from the remaining valves. This allows one to vary the volume of air which is discharged along the length of the ridge beam.

The roof of the greenhouse may have the shape of a number of parallel oriented saddle roofs each provided with the ridge beam. Such a greenhouse may have any type of transparent walls, suitably glass or polycarbonate. Such transparent walls are suitably fixed in a frame work. The ridge beam is suitably part of such a frame work providing the structure of the greenhouse itself. The greenhouse may also be of the tunnel type and wherein the transparent walls are transparent polymer sheets. At the upper end of the tunnel the ridge beam is provided running in the same direction as the elongated tunnel. More than one tunnel may be positioned in parallel forming one space.

The greenhouse is suitably a so-called semi-closed greenhouse. Such a greenhouse is suitably provided with means to take in air from the exterior of the greenhouse, an air conditioning mixing zone suited to mix air from the exterior of the greenhouse with air from within the greenhouse and means to distribute air from the air conditioning zone to the interior of the greenhouse via a multitude of ventilation ducts fluidly connected to the air conditioning mixing zone.

Such a greenhouse will be typically operated with a small over pressure resulting in that the flow direction in the openings of the ridge beam will be from the interior to the exterior of the greenhouse. This avoids that insects can enter the greenhouse and may avoid additional measures such as netting and the like. The pressure within the greenhouse may be between 0 and 100 Pa higher and preferably between 10 and 20 Pa higher than the pressure exterior of the greenhouse.

The greenhouse may be operated by only recirculating air from within the greenhouse to the air conditioning zone and back to the interior of the greenhouse. In this mode no external air is let in and the openings in the ridge beam may suitably be closed or only opened if the pressure within the greenhouse has to be decreased. In another mode of operation air from the exterior of the greenhouse is let into the air conditioning zone only and discharged via the openings in the ridge beam. No recirculation of the air from within the greenhouse via the air conditioning zone takes place. This mode may be omitted because it has been found that a minimal recirculation is favourable. In the third and most used mode of operation air from the exterior of the greenhouse is mixed with air from within the greenhouse in the air conditioning zone and fed to the interior of the greenhouse via the ventilation ducts. The net excess air entering the greenhouse will be discharged via the openings in the ridged beam in order to avoid that the pressure within the greenhouse exceeds its safe limits. Optionally additional openings may be present to discharge the excess air.

The ventilating ducts may be any device which provides a substantially even distribution of the air into the greenhouse. Preferably the air is discharged from these ducts in the greenhouse at a position below the cultivation. Examples of such ventilating conduits are for example described in EP1464219, WO0076296, NL1038219 and in US2010/0126062.

The air conditioning zone is suitably provided with means to cool, heat, humidify or dehumidify the air before it is distributed into the greenhouse. Such means are well known and for example described in WO2004032606, WO0076296, WO2015/012698 and WO2008002686.

The invention is also directed to the ridge beam as described above and further illustrated in the Figures.

The invention is also directed to a process to condition the air within a greenhouse comprising of transparent walls and a structure comprising of one or more ridge beams as part of a roof of the greenhouse bymaintaining a pressure difference between the average pressure within the greenhouse and the pressure exterior to the greenhouse,taking in air from the exterior of the greenhouse and mixing this air with air taken from the interior of the greenhouse to obtain conditioned air,distributing the conditioned air via a forced flow to the interior of the greenhouse, anddischarging a volume of air from the interior of the greenhouse via openings present in the one or more ridge beams such to maintain the pressure difference.

The area of openings in the ridge beam per axial length of the ridge beam is preferably between 0.01 and 0.1 m2/m and more preferably between 0.01 and 0.04 m2/m.

The discharge of air via the openings of the ridge beam is suitably controlled such that the pressure within the greenhouse is between 0 and 100 Pa higher and preferably between 10 and 20 Pa higher than the pressure exterior of the greenhouse.

Preferably the volume of air discharged via the openings in the ridge beam is performed via openings at the leeward side of the ridge beam in a situation that a flow of external air flows over the ridge beam under an angle thereby defining a leeward and windward side of the ridge beam. This is advantageous for the reasons earlier discussed.

Preferably the discharge of air via the openings in the ridge beam is performed via openings which direct the air in a side ways direction relative to the ridge beam. For this process a rotatable valve rotating over an axis parallel to the ridge beam is used to either direct the majority of the air to one side or to the other side. More preferably the process is performed in the greenhouse according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a ridge beam4having an upper part, which in use extends some distance above a roof5of a greenhouse1. The roof5is composed of glass panels2which fit in an elongated sleeve of the ridge beam4as shown. The upper part comprises of two elongated side zones6,7present at either side of the upper part of the ridge beam4. The ridge beam4is comprised of stationary part3awhich is part of the structure3of the greenhouse and one or more elongated hollow spaces8. The ridge beam4is provided with one or more closable openings9in both side zones6,7.

FIG.1further shows that the hollow space8of the ridge beam4has a tubular shape. In this hollow space8a valve18is rotatably positioned. The valve18is provided with openings22awhich aligns with opening9at side7as shown and opening22bsuited to align with opening9at side6in another rotatable position of valve18. A surface23present along the length of valve18closes opening9at side6in the valve18position shown inFIG.1.

In this figure the opening9at side zone7aligns with opening22aof valve18and fluidly connects the exterior10of the greenhouse1with the elongated hollow space8of the ridge beam4. An opening11at the lower end12of the ridge beam4aligns with opening22bof valve18and fluidly connects the interior13of the greenhouse1with the elongated hollow space8. By consequence the interior13of the greenhouse1is fluidly connected via opening9at side7with the exterior10of the greenhouse1. By rotating valve18clock wise the size of opening9at side7and the size of opening11shall become smaller. In this manner it is possible to vary the flow of air leaving the greenhouse1and to control the pressure difference between the interior13and the exterior10of the greenhouse. By rotating the valve18even further opening9at side7may be fully closed and opening9at side6will align with opening22bof valve18and opening11will align with opening22a. In this position the interior13of the greenhouse1is fluidly connected via opening9at side6with the exterior10of the greenhouse1. This illustrates that the ridge beam having a valve18is able to open at either side of the ridge beam and close at its opposite side. The ridge beam4having a valve18shall be further illustrated inFIGS.3-6.

FIG.2shows another design for the rotating valve. The upper end part of the ridge beam4is an elongated cap valve30which can rotate along an axis31running parallel with the ridge beam4. Axis31runs within the hollow space8of the ridge beam4. The cap valve30comprises a curved section27of a tube cut along its length, an elongated surface26connected to the curved section27and a hollow opening28running in the middle of the elongated surface. Hollow opening28is rotatably connected to an axis29which is part of the lower stationary part12of the ridge beam4. The curved section27as shown has an angle of about 180° and may have an angle of between 60 and 270°. The angle is here defined as the angle α between the two planes running from the ends of curved section27to axis31. At the lower angles range for section27it is desirable to provide the ridge beam4with curved walls29aand29b. The cap valve30is shaped such that in a first rotatable position one or more openings9in the first elongated side zone6are present which in use fluidly connect the exterior10of the greenhouse1with the elongated hollow space8of the ridge beam4and wherein the second elongated side zone7is closed by the cap valve30and in a second rotatable position one or more openings9in the second elongated side zone7are present which in use fluidly connect the exterior10of the greenhouse with the elongated hollow space8of the ridge beam4and wherein the first elongated side zone6is closed by the cap valve30.

FIG.3shows a cross section of valve18showing surface23and polymer parts33,34and35. Polymer parts33,34and35extend a small distance radially outwards and provide a sliding surface which contacts the interior of hollow space8of ridge beam4. InFIG.4polymer parts33,34and35are shown separately. The parts are separate parts to enable an easier assembly with valve18.

FIG.5shows a section of valve18. Two rows20and21of openings22aand22brespectively. Elongated surface23separates the inner tubular space of the valve18into an elongated space24fluidly connected to the two rows20,21of openings22a,22band a remaining space25. The polymer part33is shown half way the section of valve8providing separated hollow spaces8. Connecting means36are provided to connect to the illustrated section to a next section of the valve18.

FIG.6shows a valve18as present inside a section of the ridge beam4ofFIG.1. The rotational position of valve18in this figure is such that the interior13of the greenhouse1is not fluidly connected to the exterior10of the greenhouse1via the openings9of the ridge beam4. Surface23encloses opening11(not visible) from the hollow space8. The valve may be changed from one position to another position by rotation along an axis39running parallel with the ridge beam4. The valve18is connected to a transmission (not visible) which in turn is rotatably connected to a motor39apositioned below the section of ridge beam4. Further connecting means38and38aare shown which are used to connect the section of ridge beam4to a next section of ridge beam4. Also the section of valve18is connected to a next section of valve18by connecting means18. In this way one motor39amay rotate a multiple of sections of the ridge beam.

FIG.7a-cshows a variant of the valve18ofFIG.6. The rotating valve comprises an elongated segment of a cylinder23awhich in use can rotate within an tubular elongated space8. The elongated segment of a cylinder23ais provided with support parts24a, which support parts24awill in use rotate within tubular housings25a. The support parts24aand corresponding tubular housings25aare spaced apart along the ridge beam such to create openings9. Tubular housing25aand optional further supports26aare preferably disconnectable. InFIG.7athe valve18ais shown in a closed position wherein the interior13of the greenhouse1is fluidly closed from the elongated space8and opening9. InFIG.7ba valve18arotational position is shown wherein the interior13of the greenhouse is fluidly connected to an opening9at side7. InFIG.7ca rotational position of valve18ais shown wherein the interior13of the greenhouse is fluidly connected to opening9at side6. This design enables one to more easily remove the valve18aby simply disconnecting tubular housings25a. Further less contact area will result and thus less risk that the system would block.

FIG.8shows a greenhouse1with three saddle roofs5each provided with a ridge beam4according to this invention and a gutter48. A commercial greenhouse may have between 1 and 100 or even more than 100 of such saddle roofs5. At the floor of the greenhouse1seven ducts44are shown. A greenhouse may have between 2 and 250 or even more of such parallel positioned ducts44. The ducts44run parallel with the ridge beam4inFIG.8. It is also possible to position the ducts44perpendicular to the direction of the ridge beam4. Air is distributed from these ducts via openings50to the interior13of the greenhouse. The driving force for this distribution of air is provided with fans49at one end of the duct. The opposite end of duct44is closed. The air entering fans49is preferably conditioned in an air conditioning mixing zone as shown inFIG.8.

FIG.9shows a cross section AA′ of semi-closed greenhouse shown inFIG.8provided with means40to take in air from the exterior10of the greenhouse. The means40are openings in a side wall of the greenhouse which may be opened or closed by means of a shutter43. Further an air conditioning mixing zone41is shown where air from the exterior and air45from within the greenhouse1can mix. The thus mixed air is distributed to the interior of the greenhouse using means49, suitably a fan connected to a ventilating duct44. Preferably multiple and parallel oriented ventilation ducts are present to evenly distribute the air43in the greenhouse. The mixing zone41is preferably a single space running along one side of the greenhouse. The position of shutter47is preferably elevated enough to achieve a flow of air in the direction of shutter47which is substantially above the vegetation in the greenhouse. The amount of air45from within the greenhouse entering the mixing zone may be controlled by shutter47. By controlling shutters47and43and the openings in ridge beam4and the ventilating power of fans49one may achieve the different modes of operation as discussed above. The amount of air entering the greenhouse via means40will be about the same amount of air leaving the greenhouse via the openings in ridge beam as air46.

FIG.10a-cshows another example of a ridge beam according to the invention.FIG.10bshows a ridge beam61having openings9at either side6,7of the ridge beam4. A first wall part56is present as the elongated side zone6and a second wall part57as the opposite elongated side zone7. The wall parts56,57are rotatably connected to the fixed part3aof the ridge beam at their lower ends via elongated hinges52,55. The wall parts56,57are further both rotatably connected to an elongated bridging part51at their upper ends via elongated hinges53,54. The axis of rotation of all four rotatable connections or hinges52,53,54,55run parallel with the elongated ridge beam4. The hinges52,53,54,55are elongate curved ends running along the length of the fixed part3a, the wall part56, the bridging part51, the wall part57and again fixed part3a.

Hinges52,53,54,55enable that the bridging part can tilt in different positions and at least from the positions shown inFIGS.10a-cto another illustrated position. A hollow space58, an opening59at the lower end60of the ridge beam61is shown. InFIG.10athe bridging part51closes openings9at either side6and7of the ridge beam. InFIG.10bthe interior13of the greenhouse is fluidly connected with hollow space58which in turn is fluidly connected with openings9at either side6,7of the ridge beam61. InFIG.10cthe valve51encloses only openings9at side7while the openings9at side6are open and fluidly connect to the hollow space58and to the interior13of the greenhouse via opening59. Air flow60illustrates the flow path of the air as discharged from the greenhouse to the exterior.

FIG.11shows another example of a ridge beam63according to the invention. The ridge beam4is comprised of stationary part3awhich is part of the structure3of the greenhouse. The ridge beam63has an upper part, which in use extends some distance above a roof5of a greenhouse1. The upper part comprises of two elongated side zones6,7present at either side of the upper part of the ridge beam63. The elongated upper part of composed of two elongated and upwardly extending walls64,65which meet at their upper ends66. The walls64and65are provided with openings9. On top of walls64,65a screen70is present which functions like the earlier described valve by being moveable in the elongated direction of the beam ridge63. The screen70is provided with openings67,68which, depending on the position of the screen70, may align with openings9in either side6or side7. When the openings68align with openings9in side7a fluid connection is provided via these openings, the hollow space69and lower opening70, between the exterior and interior of the greenhouse as shown inFIG.12. When the openings67(not visible inFIG.11) in screen70align with openings9in side6a fluid connection is provided via these openings, the hollow space69and lower opening71, between the exterior and interior of the greenhouse (not shown). In a third position all openings9on either side are enclosed (not shown).

The ridge beam as illustrated inFIGS.1-6,9and10are preferably metal extrusion profiles.