NL1044126B1

NL1044126B1 - A planar truss

Info

Publication number: NL1044126B1
Application number: NL1044126A
Authority: NL
Inventors: Peter Van Heijningen Sven; Nowé Willem
Original assignee: Alcomij Beheer Bv
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2023-03-13

Abstract

The invention is directed to a planar truss (1) for use in a roof construction in a greenhouse comprising an upper (2) and a lower (3) chord extending from one end (4) of the truss (1) to an opposite end (5), which upper (2) and lower (3) chord are connected by diagonal beams (6) and wherein at either end (4,5) of the truss (1) a vertical end beam (7,8) is present, wherein the upper chord (2) is hollow having an inner space or spaces and provided with one or more openings (12) fluidly connecting the inner space or spaces of the upper chord with the exterior of the chord, which inner space or spaces are fluidly connected to an opening in one or both of the vertical end beams (7,8) and/or fluidly connected to the exterior at a position below the upper chord (2).

Description

A PLANAR TRUSS

The invention is directed to a planar truss comprising an upper and a lower chord extending from one end of the truss (1) to an opposite end. The upper and lower chord are connected by diagonal beams. At either end of the truss a vertical end beam is present. The invention is also directed to a roof support construction comprising of two or more upright hollow supports interconnected by the invented planar truss. The roof support is especially part of a greenhouse.

Such a truss and roof support for a greenhouse is described in NL1043187.

This publication describes a roof support for a greenhouse having hollow supports which are interconnected by planar trusses. Between the trusses a removable screen is present. Air can flow from the space above the screen via an opening in the upper end of the hollow support and via the support to a space below the screen using a fan.

The roof support of NL1043187 is advantageous because it allows a forced air flow from above the screen to below the screen. Because the air flows via the hollow supports the screen or screens themselves can be arranged in a more air tight manner avoiding air to flow into the opposite direction. A problem of the design of

NL1043187 is that the capacity to move air from the upper space to the lower space is limited by the number of supports.

WO2019/216768 describes a greenhouse having a roof which is supported by trusses. The trusses are supported by columns which extend downwards to a floor of the greenhouse. At the elevation of the trusses a removable horizontal screen is present. The screen divides the interior of the greenhouse in an upper space and a lower space. Ventilators are connected to the columns and may be provided with an air inlet to draw in air from the upper space and an air inlet to draw air from the lower space. The air from the upper space and lower space may be blended and discharged into the lower space. According to this publication the ventilators are operated as a group resulting in evenly conditions. A problem of such a system is that the amount of air which may be displaced is limited by the number of available columns. This problem may be mitigated by adding flow means to the trusses which move air from the upper space to the lower space. A problem of such flow means, involving conduits and ventilators, is that their presence decreases the light entrance of the greenhouse which is not desired.

The object of the present invention is to provide for a design which allows more air to be transported while not substantially lower the light entrance of the greenhouse.

This is achieved by the following truss. A planar truss comprising an upper and a lower chord extending from one end of the truss to an opposite end, which upper and lower chord are connected by diagonal beams and wherein at either end of the truss a vertical end beam is present, wherein the upper chord is hollow having an inner space or spaces and provided with one or more openings fluidly connecting the inner space or spaces of the upper chord with the exterior of the chord, which inner space or spaces are further fluidly connected to an opening in one or both of the vertical end beams and/or fluidly connected to the exterior at a position below the upper chord.

Applicants found that by making use of the truss itself as a flow path for air the capacity for air to flow from a space substantially above the truss to a space substantially below the truss can be increased. Further the additional flow path does not interfere with the removable screens in such a manner that air can flow upwardly between the screens and the truss. Further advantages will be described below when discussing the invention in more detail.

Terms as upper, lower, higher, above, below, horizontal and vertical are used to describe the invention in a clear manner for a truss having an orientation as it will be used in a roof support. The use of these terms do not limit the invented truss to only a truss having this orientation but also covers the same truss in other orientations.

In a first embodiment the inner space or spaces are fluidly connected to an opening in one or preferably both of the vertical end beams. Such a connection may be by a hollow beam, such as a diagonal beam running from the upper chord to the vertical end beam. More preferably such a connection is via a hollow corner element.

Such a hollow corner element may have a tilted wall running from the upper chord to the vertical end beam and two triangular side walls which cover the resulting triangular openings. The corner element sits in the corner defined by the upper chord and the vertical beam. Preferably the tilted wall is provided with a closable opening.

Such an opening is preferred because it allows one to provide a bolted connection as close to the corner between the truss and another part of a construction, suitably to a support of a roof construction. The hollow corner element thus suitably has a internal space which is fluidly connected to at least two openings in the vertical beam, wherein one opening is suited for passage of a bolt. The opening suited for passage of a bolt and the closable opening in the tilted wall are horizontally aligned.

The other opening allows a flow path for air from the hollow corner element to a hollow support to which the truss may be connected.

The hollow diagonal beam or hollow corner element is suitably connected to the vertical beam and to the upper chord by means of a weld.

The upper chord is a hollow beam having an internal space and fluidly connected to the hollow diagonal beam or to the hollow corner element via an opening in the upper chord. The hollow beam forming the upper chord is suitably provided with one or more openings fluidly connecting the internal space of the hollow beam with the ambient air at the upper end of the planar truss. These openings are preferably at the upper end side of the hollow beam.

In a second embodiment the inner space or spaces of the upper chord are fluidly connected to the exterior at a position below the upper chord via a conduit extending vertically downwards. Suitably such a conduit is a vertical hollow beam as present as part of the truss and positioned between vertical end beams. Such a conduit may run from the upper chord to the lower chord. Suitably the lower chord is hollow having an inner space or spaces and wherein the inner space or spaces are fluidly connected to the vertical hollow beam resulting in that the inner space or one of the inner spaces of the upper chord is fluidly connected to an inner space of the lower chord. The inner space of the lower chord is suitably connected to an opening in the vertical beam. Such an opening allows a flow path for air from the lower chord to a hollow support to which the truss may be connected.

The truss is suitably used as part of a roof support construction and more preferably of a roof construction of a greenhouse. A preferred roof support construction comprises of two or more hollow supports interconnected by a planar truss according to this invention and wherein the inner space of the upper chord is fluidly connected to the exterior at a position below the upper chord via an inner space of the hollow support. Suitably an air flow pathway is present from the inner spaces of the upper and optionally the lower chord to the inner space of the hollow support via the openings in the vertical beams as described above and facing openings in the hollow supports.

In a preferred roof construction the truss is connected to the hollow support at a certain elevation defining a lower space and a lower support part below the truss or trusses. The lower support part is provided with an inlet opening fluidly connecting the lower space with the inner space of the hollow support.

In a preferred roof construction a removable screen is present between two parallel and adjacent trusses of the construction, wherein the lower space is present below the screen and the upper space is present above the screen. Two or more removable screens may be present positioned above each other. A first removable screen may be present between the upper chords of two neighbouring trusses and a second removable screen may be present between the lower chords of two neighbouring trusses. In such a configuration the lower space is present below the lowest screen and the upper space is present above the highest screen.

Preferably the hollow support is provided with air displacement means for moving air from the lower space via the inner space of the hollow support to the internal space of the upper chord.

The support is suitably a column as typically used in greenhouse roof support constructions adapted for use as a hollow support as described in the afore mentioned NL1043187. The support is suitably made of construction steel and has a rectangular cross-section. To two side walls of such a support the vertical breams of a truss can be connected. The two remaining front walls run parallel with the truss. A preferred hollow support has a part at the elevation of the truss or trusses wherein the front walls are substantially flush with the truss or trusses. Suitably the two front 5 and flush walls have a horizontal length (L1) which is larger than the horizontal length (D1) of the two side walls.

The part at the elevation of the truss or trusses is preferably a separate part which may be connected to a lower support part to form the support. The lower support part suitably also has a rectangular cross-sectional area. The horizontal length (D2) side walls of the lower part are preferably larger than the horizontal length (D1) of the side walls of the upper part and the horizontal length (L2) of the front walls of the lower part are suitably smaller than the horizontal length (L1) of the front walls of the upper part. These relative dimensions are preferably chosen such that the upper part can sit between the two front walls of the lower part. By making cut outs of the front walls of the upper support part and cut outs of the side walls of the lower support part the lower and upper part can interlock.

The invention is also directed to a greenhouse comprising a roof support as described above, wherein a grid of supports are connected by at least two parallel rows of trusses and wherein between two neighbouring rows of trusses a removable screen is present.

Suitably an air displacement means are present to move the air via the truss and hollow support to the lower space. Suitably a ventilator is used. Such a ventilator may be connected to a support at an elevation where one desires to discharge air to the lower space. A preferred ventilator comprises a housing having opposite first and second ends and an axial rotor arranged in a ventilator flow path, wherein the ventilator flow path has an inlet at the first end of the housing fluidly connected to the hollow inner space of the support and an outlet at the second end of the housing fluidly connected to the lower space of the greenhouse. The additional flow path fluidly connects a further opening in the housing with the ventilator flow path such that due to a venturi effect air from the lower space flows through the additional flow path towards the ventilator flow path thereby flowing past the temperature and/or humidity sensors. In this way the temperature and/or humidity of the air in the vicinity of the ventilator can be measured. In order to be able to continuously and optimally measure a minimum air flow in the air flow path is required to create the venturi effect. This means that the ventilator are suitably operating at least at a minimum capacity.

The invention is also directed to the following method. Method to control the climate in a greenhouse interior space comprising a roof support construction comprising of two or more parallel rows of trusses which trusses are supported by supports and wherein between the trusses a removable screen or screens are present defining an upper space positioned above the removable screen or screens and a lower space positioned below the removable screen or screens by displacing air from the upper space to the lower space via one or more hollow parts of the trusses.

Air may be displaced from the upper space to the lower space via the hollow parts of the supports in series with the air displaced in the one or more hollow parts of the trusses. Air may in addition or alternatively be displaced from the upper space to the lower space via hollow parts of the supports and via the one or more hollow parts of the trusses in parallel.

The amount of air to be displaced will influence the local temperature and/or humidity. To achieve a desired temperature and/or humidity in the lower space where the plants are growing more or less air can be displaced from the upper space to the lower space. Preferably the temperature and/or humidity is measured in the lower space resulting in measured temperature and/or humidity values. By displacing air from the upper space to the lower space the temperature and/or humidity is altered and the volume of air which is displaced is based on the measured temperature value and/or a measured humidity value. Preferably the local temperature and/or local humidity is measured at numerous different local positions in the lower space resulting in numerous local measured temperature and/or humidity values, and air is displaced from the upper space to the lower space wherein the volume of air which is displaced at one local position is based on the measured temperature value and/or a measured humidity value at said local position.

The above method is preferably performed in a greenhouse according to this invention as described above.

The invention shall be illustrated by the following Figures.

Figure 1 shows a planar truss (1) having an upper (2) and a lower (3) chord extending from one end (4) of the truss (1) to an opposite end (5), which upper (2) and lower (3) chord are connected by diagonal beams (6) and wherein at either end (4,5) of the truss (1) a vertical end beam (7,8) is present.

Figure 2 shows a detail of Figure 1. At the corner of the upper chord (2) and vertical beam (7) a hollow corner element (9) is shown.

Figure 3 shows two planar trusses (1,1a) of Figures 1 and 2 as connected to a hollow support (21) as part of a roof structure. One truss is connected to one side wall of the hollow support (21) and the other truss connected to the opposite side wall of the hollow support (21). The trusses (1,1a) are connected to the hollow support (21) by means of a bolted connection at its upper end (as shown in Figure 4) and by means of a clamp connection (31) effected by bolts at either side of the hollow support (21). The hollow support (21) is open at its upper end (32).

Additionally an opening (32a) may be present in the hollow support (21) in the side wall at an elevation above the point where the truss (1) is connected. The hollow upper chord (2) is a hollow beam (14) and is provided with two openings (17) fluidly connecting the internal space (15) of the hollow beam (14) with the ambient air at the upper end of the planar truss (1).

Figure 4 illustrates the air flow of the roof construction as shown in Figure 3.

Part of the air enters the hollow support (21) via open upper end (32) as air flow (33) and part of the air enters hollow support (21) via the hollow beam (14) and hollow corner element (9) as flows (34a,34b). In this Figure the position of the upper bolt (35) is shown.

Figure 5 shows a rood construction wherein the upper chord (2) of both trusses (1) is provided with an opening (12) fluidly connecting the exterior of the chord (2) with the inner space or spaces of chord (2). A hollow diagonal beam (36) fluidly connects the inner space of chord (2) with the inner space of a hollow lower chord (3). The inner space of the lower chord (3) is fluidly connected to an opening (37) in vertical end beams (7,8). The openings (37) are positioned at an opening in an upper support part (25b) thereby fluidly connecting the inner space of the lower chord (3) with the inner space (23) of the hollow support (21). Upper support part (25b) sits on lower support part (25a). In this figure also a roof gutter support (38) for a saddle roof is shown which is bolted to the hollow support (21) at its upper end (32). Part of the air enters the hollow support (21) via open upper end (32) as air flow (39) and part of the air enters hollow support (21) via the hollow beam (14), hollow diagonal beam (36) and hollow lower chord (3) as flows (40a,40b).

Figure 6 shows al alternative for the roof support construction of Figure 5 wherein the hollow diagonal beams (36) are directly connected to the vertical end beams (7,8). Part of the air enters the hollow support (21) via open upper end (32) as air flow (39) and part of the air enters hollow support (21) via the hollow beam (14) and hollow diagonal beam (36) as flows (41a,41b).

Figure 7 shows a roof construction wherein the inner space or spaces of beam (14) of upper chord (2) is fluidly connected to the exterior at a position below the upper chord (2) via a conduit (42) extending vertically downwards. Such a conduit is preferably present in combination with a hollow support (21) as shown in Figures 3- 6. In this way two separate air flows result from the upper space (44) to the lower space (43), namely one via the conduit (42) extending vertically downwards directly to the lower space (43) and one via the hollow support (21). The conduit (42) extending vertically downwards is preferably provided with a ventilator (not shown) which may be placed at the outlet opening of the conduit (42) in the lower space (43).

Figure 7a is a detail of Figure 7 indicated by the box with the arrow (box and arrow are not part of the structure).

Figure 8 and 8a shows a variant of the roof construction of Figure 7 where the conduit (42) extending vertically downwards is fluidly connected to the inner space of a hollow lower chord (3), which inner space is fluidly connected to an opening (37) in vertical end beams (7,8) as in Figure 5. The hollow support (21) is provided with a hollow corner element (9) as in Figures 3 and 4. This roof construction is advantageous because air from a wider area in the upper space (44) can be sucked into the hollow support (21) using a single ventilator as present at a lower position on the support (21).

Figure 9 shows a cross-section of an end part of a truss (1) which may be used in a roof construction of Figure 8/8a. The hollow corner element (9) has a internal space (10) which is fluidly connected to at least two openings (11,11a) in the vertical beam (7,8), wherein one opening (11a) is suited for passage of a bolt (35) which may be positioned as shown in Figure 4. The hollow corner element (9) has a tilted wall (13) running from the upper chord (2) to the vertical end beam (7,8) and wherein the tilted wall (13) is provided with a closable opening (13a). The upper chord (2) is a hollow beam (14) having an internal space (15) and wherein opening (12) in the upper chord (2) comprises of an opening (16) fluidly connecting the hollow space (10) of the corner element (9) with the internal space (15) of the hollow beam (14) and one or more openings (17) fluidly connecting the internal space (15) of the hollow beam (14) with the ambient air at the upper end of the planar truss (1). At least one opening (17) is an opening (17a) which is horizontally further spaced away from the nearest vertical end beam (7,8) than opening (16).

Figure 10 is an exterior view of the truss of Figure 9.

Figure 11 shows how upper support part (25b) sits on lower support part (25a) as part of hollow support (21) as a intersected transition column (21). The upper and lower support parts have a rectangular cross-sectional area. The horizontal length (D2) of the side walls (45) of the lower part (25a) are larger than the horizontal length (D1) of the side walls (46) of the upper part (25b). The horizontal length (L2) of the front walls (47) of the lower support part (25a) are smaller than the horizontal length

(L1) of the front walls (48) of the upper support part (25b). These relative dimensions are chosen such that the upper part can sit between the two front walls of the lower part as shown. By making cut outs of the front walls (48) of the upper support part (25b) and cut outs of the side walls (45) of the lower support part (25a) the lower support part (25a) and upper support part (25b) can interlock. The length of the interlocking upper and lower parts is referred to as the interlocking length (49).

The horizontal length (D1) of the side walls (46) of the upper support part (25b) is substantially the same as the horizontal length of the vertical end beam (7,8). In this way the support column (21) and truss (1) are more or less flush such that the removable screens can run past the combined construction in a more or less air tight manner.

Figure 11a shows a horizontal cross sectional view where the lower support part (25a) is intersected with an upper support part (25b). Because part of the side wall (45) of the lower support part (25a) is cut away and because part of the front walls (48) of the upper support part (25b) is cut away an increase in cross sectional area for the down streaming air is achieved by this design in the direction of the air flow. This is advantageous because less pressure drop will then result in the interlocking length (49).

Claims

i CONCLUSIONS

Flat lattice girder (1), comprising an upper (2) and a lower (3) edge, each extending from one end (4) of the lattice girder (1) to an opposite end (5), the upper ( 2) and the bottom (3) edges are connected by diagonal beams (6}, and where a vertical end beam (7, 8) is provided at both ends (4, 5) of the lattice girder {1}, where the top edge (2) is hollow and includes an interior space or spaces, and is provided with one or more openings (12) which form a fluid communication between the interior space or spaces of the upper rim and the exterior environment of the rim, the internal space or spaces are fluidly connected to an opening in one or more vertical sine beams (7, 8), and/or are fluidly connected to the external environment in a position located below the top edge (2). 1, the interior space or spaces of the top rim (2) being fluidly connected to an opening (11) in the vertical beam {7, 8) via a concave corner element (8),

Flat lattice girder according to claim 2, wherein the concave corner element (9) comprises a sloping wall (13) running from the top edge (2) to the vertical end beam {7, 8), and wherein the sloping wall (13) is provided with a closable opening (13a).

Flat lattice girder according to claim 3, wherein the hollow corner element (9) comprises an internal space (10) which is fluidly connected to at least two openings (11, 11a) in the vertical beam (7, 8), one opening ( 112) is suitable for installing a bolt thereby,

A flat lattice girder according to claim 4, wherein the opening (11a) suitable for inserting a bolt therethrough and the closable opening (13a) in the sloping wall (13) are horizontally aligned.

Flat lattice girder according to any one of claims 1 to 5, wherein the concave corner element (9) is connected to the vertical beam (7, 8) and to the top edge {2} by means of a welded connection.

A flat lattice girder according to any one of claims 1 to 6, wherein a hollow corner element (8) is connected at both ends (4, 5),

Flat lattice girder according to any one of claims 1 to 7, wherein the top edge (2) is a hall beam (14) comprising an internal space (15), and wherein opening (12} in the top edge (2) consists of an opening (18) which forms a fluid communication between the aforementioned hollow space (10) of the corner element {9} and the internal space (18) of the hollow beam (14), and one or more openings (17) which fluid communication between the interior space (15) of the hollow beam (14) and the ambient air around the upper end of the flat truss (1).

A flat lattice girder according to claim 8, wherein at least one opening (17) is an opening (17a) horizontally spaced at a greater distance from the nearest vertical end beam (7, 8) than opening (186). A flat lattice girder according to claim 1, wherein the interior space or spaces is or are fluidly connected to the exterior environment in a position located below the top edge (2) via a conduit extending vertically downwards.

A flat lattice girder according to claim 10, wherein the conduit is a vertical hollow beam as present as part of the lattice girder, and is positioned between vertical end beams (7, 8).

A flat lattice girder according to claim 11, wherein said lower edge is hollow and includes an interior space or spaces, and wherein the interior space or spaces is or are fluidly connected to the vertical hollow beam.

A roof support structure (20) comprising two or more hollow supports (21) interconnected by a flat lattice girder (1) according to any one of claims 1 to 8, wherein the opening in one or both of the vertical end beams (7, 8) is fluidly connected to an interior space (23) of the hollow support (21), and/or wherein the interior space or spaces of the upper rim is or are fluidly connected to the external environment in a position which is lower than the top edge (2), through an internal space (23) of the hollow support (21).

A roof support structure, according to claim 13, wherein the truss (1) is connected to the hollow support {21}, which includes an internal space (23), at a predetermined height through which a lower space (25) and a lower strut section (25a) are defined below the lattice girder or lattice girders, and wherein the lower support section (253) is provided with an inlet opening (26) which fluidly communicates between the lower space (25) and the interior space (23) of the hollow support (21). A roof support structure as claimed in claim 14, wherein the lower support member (25a) intersects with an upper support member (25b), the lower support member (25a) and the upper support member (25h) having a rectangular shape. cross-section, with two side walls and two front walls (45, 46, 47, 48), the horizontal length (D2) of the side walls (45) of the lower support part (25a) being greater than the horizontal length (D1) of the side walls (46) of the upper support part (25h), and the horizontal length (L2) of the front walls (47} of the lower support part (25a) are less than the horizontal length (L1) of the front walls (48) of the upper desi, the upper and lower support members (25a, 25b} being intersected for an interlocking length (48) by cuts (50) in the front walls (48) of the upper support member {25b), and by means of cut-outs (51) in the side walls (45) of the lower support part (25a). A roof support structure according to claim 15, wherein the horizontal length (D1) of the side walls (46) of the top support member (25b) is substantially the same as the horizontal length (D3) of the vertical end beam (7, 8 ).

A roof support structure according to any one of claims 14 to 16, wherein the support is provided with air displacement means (213) for displacing air from the underside space (25), through the internal space (23) of the hollow support (21), to the inner space (10) of the hollow upper rim (2). 2918. Greenhouse and support structure for a roof comprising according to any one of claims 13 to 17, wherein the instances of a grid of supports (21) are connected by at least two parallel rows of lattice girders (1), and wherein between two adjacent rows of lattice girders (1) one or more removable screens are present.

Greenhouse according to claim 18, wherein a first removable screen is present {between the upper edges (2) of two adjacent lattice girders (1), and wherein a second removable screen is present between the lower edges (3) of two adjacent spaced lattice girders (1).

20. Method for controlling the climate in an internal space of a greenhouse, wherein the greenhouse comprises a support construction for the roof, with two or more parallel rows of lattice girders, wherein these lattice girders are supported by support structures, and wherein a removable screen or removable screens are present, leaving no upper space! defined above the removable screen or screens, as well as a bottom space positioned below the removable screen or screens, by moving air from the top space to the bottom space through one or more hollow parts of the trusses.

A method according to claim 20, wherein air is displaced through hollow members of the support structures, in series with the air displaced in the one or more hollow members of the trusses, or parallel to the air displaced in the one or more hollow parts of the lattice girders.

A method according to any one of claims 20 to 21, wherein (i) the local temperature and/or the local humidity is or are measured in various different local positions in the lower space, resulting in various locally measured temperature and/or humidity values. or humidity level values, and (ii) moving air from the upper space to the lower space, wherein the volume of air moved in a local position is based on the measured temperature control value and/or a measured humidity value in said local position.

A method according to any one of claims 20 to 22, as applied in a greenhouse according to any one of claims 18 to 19,