Box beam, box beam system and method of box beam manufacture

Abstract

The present invention relates to a box beam consisting of two external glass plates separated from each other by a closed metal structure as a perimeter frame between the glass plates, and where these two external glass plates are connected to the closed metal structure by structural and gastight joints, so that the enclosed space between the glass plates and the closed metal structure forms a chamber comprising a gas. The invention also relates to a system comprising a box beam and, in addition, means for compensating pressure variations and optionally for further mitigating temperature variations of the gas contained in the inner chamber of the box beam, so as to keep the pressure of this gas equal to or close to the outside atmospheric pressure and optionally to keep the temperature of the chamber close to a user comfort temperature. Finally, the invention also relates to a method of manufacturing such a box beam.

Description

[0001] BOX BEAM, BOX BEAM SYSTEM AND METHOD OF BOX BEAM MANUFACTURE

[0002] DESCRIPTION

[0003] OBJECT OF THE INVENTION

[0004] The present invention relates to a box beam acting as a structural unit, suitable for installation alone or in combination with more adjacent structural units. The box beam is characterised by high structural rigidity, optical transparency, durability and versatility as it can be installed both horizontally and vertically.

[0005] The present invention also relates to a system comprising such a box beam and, in addition, means for compensating for variations in the pressure of the gas inside the box beam chamber which may occur.

[0006] Finally, the present invention also relates to a method of manufacturing the box beam.

[0007] BACKGROUND TO THE INVENTION

[0008] Box beams are structural elements belonging to the tubular bar typology. The typical cross-section of the box beam has a solid, rectangular outer perimeter enclosing a hollow space or chamber inside. Existing box beams are generally made of metal plates, for example aluminium or steel, riveted, bolted or welded, or of reinforced and prestressed concrete formed and cured as a single piece, and these box beams are therefore optically opaque elements. The rectangular cross-section of the box beams consists of two flanges and two webs, orthogonal to each other and rigidly connected. The stiffness of these connections provides continuity to the stress and strain fields and thus produces degrees of composite action, between webs and flanges, close to unity, i.e. the theoretical maximum. The stiffness of the connections and the high degree of composite action means that the flanges work together mechanically, which gives the box beam very good structural properties, particularly high stiffness and resistance to bending and torsion. Under bending loads, in a cross-section, each of the flanges resists essentially normal internal forces of opposite sign (tensile and compressive respectively) and the webs resist tangential internal forces as well as normal internal forces. Under torsional loads, in a cross-section, both webs and flanges resist tangential internal forces. However, no highly transparent box beams are known in the state of the art which can act as a structural unit, for example as a transparent facade module for main entrances of office buildings, institutions or hotels, and which can be very variable in size, i.e. from small, medium to large, compact, thin and structurally strong. Norare highly transparent box beams known in the state of the art that incorporate a system to equalise the pressure of their interior gastight chamber with respect to the external atmospheric pressure, thus eliminating cyclical mechanical stresses of climatic origin.

[0009] Additionally, nor are box beams known in the state of the art that incorporate an active system to control the temperature of the chamber in order to mitigate temperature variations in this chamber, thus increasing the thermal insulation capacity of the box beam.

[0010] The term "mitigate" is used because, once a target temperature value (setpoint or reference value) has been established, the use of control means will apply corrective measures to achieve this value, although the value achieved will always show a certain error that will be under control and will be the variable that determines the degree of intervention of the control means to achieve this setpoint. That is, the use of the term "mitigate" implies the use of means of control. The terms setpoint and reference value are used interchangeably in the context of the present invention.

[0011] Transparent elements with a hollow rectangular cross-section and enclosing an inner chamber exist in the state of the art; however, the cross-section elements are not rigidly connected to each other and consequently work mechanically disconnected, which is highly inefficient and produces very low bending and torsional stiffnesses. This is the case of double glazing type insulating units where the joining systems of the two glass plates to form an insulating unit are based on flexible polymeric joints, for example of the silicone type. These units lack relevant degrees of composite action and require for their installation, for example as a facade closure unit of a building, the existence of an auxiliary substructure with load-bearing capacity. This substructure is generally made up of bulky metal mullions and transoms, to which the insulating unit is fixed, and which allow to resist the lateral loads that act on the glass plates, mainly due to the action of the wind. The provision of this substructure, which usually protrudes into the interior of the building, causes a number of disadvantages, including a high consumption of material resources and a loss of transparency, slenderness and usable space inside the building.

[0012] Such known insulating units cannot be considered as a structural element as the glass plates do not work together, but are mechanically disconnected from each other, which is highly inefficient. Consequently, these units have no load-bearing capacity except by using very thick glass plates, which is neither mechanically optimal nor environmentally sustainable.

[0013] In addition, existing insulating units do not incorporate any closed-loop circuit pressure compensation system to equalise the pressure of their inner chamber (between glass plates) with the external atmospheric pressure, which reduces the durability of these insulating units due to the risk of moisture entering the chamber and the generation of mechanical stresses in their components. Furthermore, insulating units do not incorporate a closed-loop circuit to mitigate temperature variations in their chambers, and the absence of this circuit reduces their thermal insulation capacity.

[0014] There is a need in the art to provide a highly transparent box beam that can be installed as a static or mobile structural unit, alone or in combination with other adjacent structural units, for example on a building facade, where in addition the box beam unit is capable of adopting large dimensions only limited by the maximum available dimension of the glass plates that form it, and integrating as part of the facade structure without requiring the use of reinforcement profiles (i.e. mullions and transoms) external to the box beam.

[0015] There is also a need in the art to provide a system that comprises the box beam and is also capable of efficiently compensating for any variations in pressure of the gas contained within the box beam that occur with respect to the atmospheric pressure outside the box beam, and optionally the system is capable of mitigating temperature variations in the chamber in order to increase the thermal insulation capacity of the box beam.

[0016] Finally, there is also a need in the art to provide a method of manufacturing such a box beam.

[0017] DESCRIPTION OF THE INVENTION The present invention provides a solution to the aforementioned problems by means of a box beam according to claim 1, a system which in addition to the box beam comprises means for compensating the pressure of the gas contained within the chamber of the box beam according to claim 16 and a method of manufacturing the box beam according to claim 27. Preferred embodiments of the various aspects of the invention are defined in the dependent claims.

[0018] In a first inventive aspect, the invention provides a box beam, comprising: a first glass plate, which has an outer surface and an inner surface arranged opposite to the outer surface; a second glass plate, having an outer surface and an inner surface arranged opposite to the outer surface, wherein the second glass plate is arranged parallel to the first glass plate and spaced apart from the first glass plate; two metal longitudinal profiles, essentially parallel and spaced apart, extending along a certain longitudinal path, the two longitudinal profiles being interposed between the inner surface of the first glass plate and the inner surface of the second glass plate, wherein the two longitudinal profiles comprise: a first lateral receiving surface with a first seat adapted to receive a perimeter part of the inner surface of the first glass plate, and a second lateral receiving surface, arranged opposite to the first lateral surface, with a second seat adapted to receive a perimeter part of the inner surface of the second glass plate; two metal closing profiles, configured such that the ends of the longitudinal profiles are joined by the two closing profiles at either end, forming a closed metal structure, the two closing profiles being interposed between the inner surface of the first glass plate and the inner surface of the second glass plate, and wherein the two closing profiles comprise: a first lateral receiving surface with a first seat adapted to receive a perimeter part of the inner surface of the first glass plate, and a second lateral receiving surface, arranged opposite to the first lateral surface with a second seat adapted to receive a perimeter part of the inner surface of the second glass plate; and where the first glass plate is connected to the first seat of the first lateral surface of the two longitudinal profiles and of the two closing profiles by means of a first structural and gastight joint; and the second glass plate is connected to the second seat of the second lateral surface of the two longitudinal profiles and of the two closing profiles by means of a second structural and gastight joint; and wherein the inner space bounded by the inner surface of the first glass plate, the inner surface of the second glass plate and an inner surface of the closed metal structure formed by the metal longitudinal profiles and the metal closing profiles forms a chamber, wherein the chamber comprises a gas.

[0019] The box beam of the invention consists of three main components: 1) two glass plates, 2) a closed metal structure (comprising two metal longitudinal profiles and two metal closing profiles) running perimetrically between the glass plates and 3) two structural joints, one between each glass plate and a lateral surface of the metal profiles. This means a reduction in the number of components compared to traditional double glazed insulating units, which lack self-supporting capacity and usually need to be fixed to an auxiliary substructure of mullions and transoms.

[0020] The structural connection between the closed metal structure (i.e. the set of metal profiles) and the glass plates allows the resulting box beam to exhibit a high degree of composite action and therefore high torsional and bending stiffness, as well as high mechanical strength. In contrast, the two glass plates of a traditional insulating unit lack this structural connection and the stiffness and strength is provided by the auxiliary substructure of mullions and transoms to which the insulating units are attached and which protrudes out of the plane of the glass plates. The box beam of this invention with high transparency allows for greater mechanical slenderness (i.e. reduced facade thickness) than a traditional double-glazed insulating unit system (the reduction in thickness is estimated to be up to 200 mm) as it dispenses with this auxiliary substructure. In building applications, this results in a significant increase in the optical transparency of the facade, the interior usable space of the building and the comfort of the users. Greater transparency allows for an increase in natural light, which saves energy.

[0021] Preferably, the structural and gastight joint between the glass and metal substrates of the box beam of the invention is highly efficient and produces a Degree of Composite Action close to 1, with 0 and 1 being the theoretical minimum and maximum, respectively. The term Degree of Composite Action (also known by its acronym DCA) is commonly used in the field of structural engineering to quantify, in a beam cross- section, the degree of coupling between the connected substrates. On the one hand, a value of DCA equal to 0 indicates that the substrates slide freely between them and therefore the coupling is zero. In this situation both the shear stiffness of the joint and the capacity to transfer shear stresses (shear) between substrates are zero. On the other hand, a value of DCA equal to 1 indicates the absence of relative slip, and therefore full coupling, between substrates. In this situation the shear stiffness of the joint is infinite, and the shear stresses are fully transferred between substrates without deforming the joint.

[0022] There are different definitions of the term, as the "DCA" can be calculated at a global level (for the whole box beam) or at a local level (for each cross-section of the box beam). At the global level, the DCA can be calculated from both the maximum resisted loads (ultimate load) and the maximum displacements (deflections) produced by these loads. At the local level, and in the context of this application, the DCA is calculated from the axial strains of the substrates on either side of the structural joint according to the following equation: where 81 and 82 are the axial strains of the substrates on either side of the tested joint, and SIMAX and 82MAX are the maximum values of these strains that would occur when the joint is non-existent or when the joint has zero stiffness.

[0023] In the box beam of the invention, the structural joint produces an almost total composite action between the glass and metal substrates, i.e. there is no significant relative slippage between the glass plates and the metal profiles in the sense of the Degree of Composite Action. Preferably, the DCA of the box beam will be greater than 0.75, preferably greaterthan 0.85, and more preferably greater than 0.95. In an embodiment, the DCA calculated according to the previous equation for each cross-section along the longitudinal profiles of the box beam is greater than 0.75, preferably greater than 0.85, and more preferably greater than 0.95.

[0024] As an example, and in comparison to the high DCA values of the box beam of this invention, the insulating units of double glazed panels currently on the market have DCA values < 0.10, which are very low and result in a high mechanical inefficiency. For this reason, traditional insulating units do not function mechanically as box beams and need to be reinforced externally by bulky profiles (mullions and transoms) which often protrude into the interior space of the building.

[0025] The box beam according to a preferred example of the invention differs from other existing box beams in that it has a high degree of transparency (by using two glass plates as flanges) and differs from double-glazed insulating units in that it has a high DCA value and consequently a self-supporting structural capacity. These characteristics of high transparency and structural capacity also give the box beam applications in sectors other than building, such as the automotive, nautical and aeronautical sectors, where the box beam can be integrated into the chassis of vehicles. Furthermore, the box beam covered by the invention is designed to be configured in any dimension in which the glass plates can be manufactured. At present, the maximum manufacturing dimensions of the box beam are approximately 24000 x 4600 mm.

[0026] In the context of this patent application, the term "self-supporting" means that the box beam in a simply supported configuration is mechanically stable. That is to say, the box beam can be supported and withstand external loads safely and without appreciable deformations, for example arranged in a vertical orientation, by inserting its upper side and its lower side into individual supports, for example in small U-shaped profiles.

[0027] The box beam of the invention, simply supported and subjected to a uniform lateral load (for example by wind action), exhibits a highly non-linear load-deflection response. Indeed, the existence of the metal structure between glass plates and the high degree of structural coupling (preferably DCA > 0.75, and more preferably > 0.85) between each glass plate and the metal structure provided by the corresponding structural joint, significantly reduce the in-plane displacement of the box beam during its deformation, generating axial forces in the bars of the metal structure with the result of a great reduction in the perpendicular displacement (deflection) to the glass plate.

[0028] The self-supporting capacity of the box beam, its modular prefabrication, its high level of thermal and acoustic insulation and solar protection, its ease of transport and installation and its durability contribute to environmental sustainability by reducing material consumption (for example compared to traditional double glazed units) by dispensing with metal substructures of mullions and transoms.

[0029] As the box beam covered by the invention is a prefabricated structural unit, quality control and early detection and correction of possible defects in the box beam is increased, unlike traditional facade construction where a large part of the assembly of components is carried out on site, which leads to a reduction in the quality of finishes, extended construction times and a general increase in the cost of the work, among other disadvantages.

[0030] In the context of this patent application, the term "profile" means an essentially unidirectional element where its dimension in this direction is at least one order of magnitude larger than the rest of the dimensions associated with the transverse directions determining its cross-section.

[0031] The two metal longitudinal profiles and the two metal closing profiles between the ends of the longitudinal profiles form a closed metal frame structure. The closed metal structure is arranged perimetrically between the two glass plates, to which it is structurally joined, and the space enclosed between the closed metal structure and the glass plates forms the inner chamber of the box beam. This chamber has the function of thermal and / or acoustic insulation of the box beam.

[0032] In the context of this patent application, the term 'chamber' means an inner cavity enclosed between the inner surfaces of the two glass plates and the inner surfaces of the longitudinal and closing profiles.

[0033] In the context of this patent application, the phrase "the chamber contains a gas" means that the chamber is filled with a gas. The gas is preferably dry, i.e. without moisture. Having a gas, instead of a vacuum, has the technical effect of at least partially compensating the atmospheric pressure.

[0034] Preferably, the chamber is gastight against atmospheric air, to prevent atmospheric air from entering the chamber and mixing with the gas.

[0035] In an embodiment, the box beam chamber may be completely enclosed, housing the gas, preferably an inert gas or carbon dioxide. The fact that the gas is inert prevents corrosion, for example of an oxidisable element. In an alternative embodiment, the box beam chamber may be connected to external means to compensate for variations in pressure and optionally to mitigate variations in the temperature of the gas contained within the box beam chamber, the whole chamber plus the external means configuring a closed-loop circuit, and the whole being filled with the same gas, preferably an inert gas or carbon dioxide. Said external means are adapted to control the pressure inside the box beam chamber and bring it close to or equal to the outside atmospheric pressure. Optionally, said external means are further adapted to mitigate temperature variations inside the chamber and keep said temperature of the chamber close to a predetermined user comfort temperature or close to a user comfort temperature existing inside a building when the box beam is placed, for example, on a building facade.

[0036] The main functions of the resulting box beam are the following: structural function (i.e. self-supporting element with high stiffness and strength), architectural function (high slenderness and high transparency) and building physics function (thermal and acoustic insulation between the two sides of the box beam).

[0037] Preferably, the materials of manufacture of the metal profiles and the glass panels of the box beam of the invention have similar thermal expansion coefficients, so that they expand and contract in a similar way with thermal variations and thus minimise the mechanical stresses of thermal origin in the components of the box beam.

[0038] Furthermore, preferably, the surfaces of the metal profiles and glass plates are physico- chemically compatible with the structural joints, i.e. these surfaces have a good adhesion to the material of the structural joint.

[0039] In an embodiment, the first glass plate, the second glass plate or both glass plates comprise:

[0040] (a) a single sheet of glass, or

[0041] (b) a laminate, the laminate consisting of at least two sheets of glass, in a stacked arrangement, between which is sandwiched at least one intermediate adhesive layer, preferably a polymeric layer, and more preferably a thermoplastic layer.

[0042] Depending on the specific requirements of each box beam model, the first glass plate, the second glass plate or both glass plates may consist of a single sheet of glass or a glass laminate. In an embodiment, both the first and second glass plates consist of a single sheet of glass, called monolithic glass. In another embodiment, both the first and second glass plates consist of an assembly of two or more stacked sheets of glass, referred to as laminated glass. In other embodiments, the first and second glass plates consist of a combination of these two types, i.e. one is a single sheet of glass and the other is a laminated glass plate. In some embodiments, the first, second or both glass plates comprise surface treatments in the form of coatings. These treatments can be solar control coatings and low emissivity coatings. Such treatments improve the energy efficiency of the box beam. The coatings are applied on at least a portion of the surfaces of the glass sheets.

[0043] In some embodiments, the first, second or both glass plates comprise additional coatings, such as reflective or tinted coatings, on one or more surfaces of the sheets comprising each glass plate.

[0044] In an embodiment, the first, the second or both glass plates consist of one or more sheets of annealed, heat-strengthened or tempered glass. Preferably, the first and second glass plates consist of a laminate of two sheets of heat-strengthened glass of the same thickness.

[0045] The total thicknesses of the first and second glass plates are determined based on the dimensions and the external loads to be withstood by the box beam. In an embodiment, the thickness of the first and / or the second glass plate of the box beam is between 6 and 25 mm, and preferably the thickness of each glass sheet is between 6 and 10 mm.

[0046] Preferably, the geometry of each glass plate is rectangular and flat and the maximum dimensions of the box beam are determined by the maximum dimensions of the glass plates existing on the market. By way of example, at the date of submission of this application these dimensions are approximately 24000 x 4600 mm. For the rectangular geometry of the flat glass plates, the closed metal structure (consisting of the two longitudinal profiles and the two closing profiles) is also rectangular and flat and its perimeter is identical to that of the glass plates. In this preferred configuration, the glass plates are arranged parallel to each other and separated by the closed metal structure.

[0047] In an embodiment, the glass plates have free-form plane geometries such as parallelepipeds with multiple straight sides, with curved lines of any direction or a combination of both. In these cases the enclosed metal structure is built around the perimeter of the flat glass plates.

[0048] In another embodiment, the glass plates are curved. In this case the closed metal structure has curved guidelines with respect to the strong inertia axis of the metal section.

[0049] Preferably, where the first glass plate, the second glass plate or both glass plates comprise a laminate, consisting of at least two glass sheets, between which at least one intermediate adhesive layer is interposed, the material selected for the intermediate adhesive layer of the first glass plate, the second glass plate or both glass plates is selected from one of the following: Polyvinyl butyral (PVB), lonoplastic polymer (SG), Ethylene vinyl acetate (EVA) foils preferably in cases where devices such as photovoltaic cells are encapsulated and Thermoplastic Polyurethane (TPU) in cases where increased security is required. In a specific embodiment, the intermediate adhesive layer is dyed PVB.

[0050] In other embodiments where the first glass plate, the second glass plate or both glass plates comprise a laminate of at least two glass sheets, the first glass plate, the second glass plate or both glass plates may further comprise one or more additional interlayers (i.e. in addition to the intermediate adhesive layer) between two glass sheets for decorative, communication and / or dynamic solar radiation control purposes.

[0051] In an embodiment, the box beam further comprises an opaque coating arranged on the first glass plate, on the second glass plate, or on both glass plates, and extending in a region at least occupying the interior bounded by the projection of the longitudinal profiles and of the two closing profiles on the glass plate, where the projection is according to the direction perpendicular to the said glass plate.

[0052] In a specific embodiment, this opaque coating is arranged on a surface of a sheet of glass of the first and / or a sheet of glass of the second glass plate and partially or totally hides the joints. This opaque coating, partially or totally around the perimeter, has the function of protecting the first and second structural and gastight joints from external agents, such as solar radiation which impacts on the box beam once it is assembled. This opaque coating can be applied by screen printing or by metal deposition in a magnetron.

[0053] Preferably, this opaque coating will exceed by about two millimetres the width of the lateral surface of the profiles on which the structural joint is applied.

[0054] In an embodiment, the box beam further comprises a perimeter surface treatment of one or both glass plates using an adhesion promoter product. In a particular embodiment, the first joint and the second joint extend along a closed path.

[0055] In otherwords, the first joint and the second joint are continuous and form a closed path on the metal structure and / or glass plates. Both joints are preferably arranged in the form of a bead on the metal structure and / or on the first or second glass plate.

[0056] In a particular embodiment, the first joint and the second joint are a high-strength structural adhesive, preferably a thermally cured epoxy-based adhesive.

[0057] Preferably, the joints between glass plates and metal structure is made using high strength structural adhesive, preferably thermally cured epoxy-based, wherein the cured high-strength structural adhesive when tested at room temperature has a coefficient of linear thermal expansion lower than 120-10’6(°C-1), preferably lower than 60-10’6(°C-1); a tensile and shear strength higher than 20 (MPa), preferably higher than 40 (MPa); and a stiffness characterised by a Young's Modulus higher than 200 (MPa), preferably higher than 1000 (MPa). On the one hand, the high stiffness of the adhesive allows creating degrees of composite action, DCA, higher than 0.75 and preferably higher than 0.85 between the substrates of the metal structure and glass plates, which guarantees the almost total coupling between metal structure and glass plates and consequently the functioning of the assembly as a mechanically efficient box beam. On the other hand, the high strength of the connection ensures that not only low intensity external loads but also more intense and / or accidental ones are resisted by an efficient box beam mechanism and a high DCA value.

[0058] At the same time, the high-strength structural adhesive provides a high level of gastightness against the ingress of gases and water vapour into the inner chamber of the box beam and thus prevents undesirable condensation from forming inside the chamber.

[0059] Preferably, the structural adhesive has a high toughness to avoid brittle breaks, for example due to cyclic loading, and also has a high physico-chemical compatibility with metal and glass substrates to ensure good adhesion to them, as well as to guarantee the absence of oxidation or migration of components during the curing of the adhesive and service life of the box beam. In a particular embodiment, the high-strength structural adhesive of the first joint and the second joint has a layer thickness in a range between 0.2mm to 4mm, more preferably in a range between 0.2mm to 2,5mm, more preferably in a range between 0.5mm to 2mm, more preferably in a range between 1mm and 2mm, more preferably in a range between 0.8 and 1.2, and more preferably about 1mm.

[0060] In a particular embodiment, the high-strength structural adhesive of the first joint and the second joint has a layer thickness of about 2 mm.

[0061] Preferably, the high-strength structural adhesive of the first joint and the second joint has a constant width, equal to or less than the width of the perimeter metal structure, without overflowing the adhesive into the box beam chamber.

[0062] Optionally, if a high-strength structural adhesive is chosen for the first joint and the second joint, the lateral contact surfaces of the metal structure and inner surfaces of the glass plates with the structural adhesive can be pre-treated with adhesionpromoting and / or corrosion-protective primers to improve the adhesion of the structural adhesive over the lifetime and thus increase the durability of the box beam.

[0063] In an embodiment, the longitudinal profiles and the closing profiles form a rectangular closed perimeter path, where each longitudinal profile and each closing profile configures one side of the rectangle.

[0064] Thus, the metal structure forms a closed rectangular frame where two parallel sides are constituted by the two longitudinal profiles and the other two parallel sides are constituted by the two closing profiles. Each profile is orthogonal to the adjacent profiles, to which it is joined at their ends, and the joints are preferably made by welding, which maximises the mechanical efficiency and gastightness of the frame.

[0065] In a particular embodiment of the rectangular closed metal structure, the first and second glass plates have the same width and length dimensions.

[0066] Preferably, the geometry of each glass plate and the metal structure is rectangular and flat, all elements having the same width and length. In this preferred configuration, the glass plates are arranged parallel to each other and separated by the metal frame. Depending on the specific application, the first and second glass plates can have the same thickness or different thicknesses.

[0067] In an embodiment, the longitudinal profiles and the closing profiles are configured according to an appreciably polygonal cross-section, preferably a rectangular crosssection.

[0068] In this embodiment, the smaller side of the rectangle corresponds to the lateral contact surface with the structural joints and the larger side of the rectangle corresponds to the outer and inner surfaces of the metal structure.

[0069] Preferably, the smaller side of the rectangle does not exceed approximately 20 mm.

[0070] In some embodiments where the first joint and the second joint are a high strength structural adhesive, the areas of the two lateral surfaces of the metal structure configured to be in contact with the adhesive joints are subjected to an abrasion treatment to increase their roughness and thus increase their bonding capacity with the adhesive. Additionally, these surfaces may be treated with a corrosion protection and / or adhesion promoter product to also improve the bonding capacity and durability of the adhesive joint.

[0071] In some embodiments, one or more surfaces of the metal structure can be surface treated to achieve an aesthetic finish.

[0072] In a particular embodiment, the longitudinal profiles and the closing profiles are solid.

[0073] Preferably, the cross-section of the longitudinal and closing profiles is solid. In other embodiments, the two longitudinal profiles and the two closing profiles are hollow or partially solid.

[0074] In the context of this application, the generic term "metallic" means any metal or metal alloy. In other words, the metal (of the longitudinal and closing profiles) has a coefficient of thermal expansion very close to that of the glass plates commonly used in construction, and consequently the coefficient of thermal expansion of the metal is between 8.5-10’6and 11.5-10’6(°C-1). This minimises the mechanical stresses of thermal origin that occur during the curing and service life of the box beam, thus extending the durability of the box beam.

[0075] Preferably the closing and longitudinal profiles are made of stainless steel or titanium as some chemical compositions of these materials allow thermal expansion coefficients in the desired range of 8.5-10’6to 11.5-10’6(°C-1) to be achieved. In addition, these materials (stainless steel or titanium) have other advantages such as high corrosion resistance, high hardness and high tensile, compressive and shear strength. Titanium has the additional advantage of having a low density and therefore brings lightness to the metal structure.

[0076] In addition, most stainless steels and titaniums are weldable.

[0077] In an embodiment, at least a part of the first lateral surface of the longitudinal profiles and the closing profiles, and / or at least a part of the second lateral surface of the longitudinal profiles and the closing profiles, and / or at least a part of a surface of the first glass plate and / or at least a part of a surface of the second glass plate is curved.

[0078] In a specific embodiment, curved glass plates are used. In this specific case, the metal structure formed by the closing profiles and longitudinal profiles has curved guidelines with respect to the strong inertia axis of the metal section of the profiles.

[0079] In some embodiments where the first and second structural joint is by means of high strength structural adhesive, each of the longitudinal profiles and closing profiles comprises a continuous perimeter channel located on the first lateral receiving surface, on the second lateral receiving surface or on both lateral receiving surfaces, and the perimeter channels are spaced apart from the inner surfaces of the longitudinal profiles and closing profiles in contact with the chamber, the perimeter channels being configured as receptacles to receive the excess adhesive from the joint and prevent it from overflowing and entering the chamber. The perimeter channel is spaced apart from the inner surface of the metal structure and functions as a receptacle to store any excess adhesive, resulting from inaccurate dosing, to prevent this excess from overflowing into the interior of the chamber when the box beam is assembled. Adhesive overflow would be an aesthetic defect. In addition, the overflow could produce a mechanical problem as the volume of overflowing adhesive, in contact only with the glass, would be poorly confined and could shrink freely during curing, which could produce significant mechanical stresses and micro-fractures in the glass. Therefore, the provision of this perimeter channel advantageously significantly reduces the risk of adhesive overflow into the inner chamber of the box beam by being able to store the excess adhesive inside and thus stopping the unwanted adhesive flow into the box beam chamber, thus ensuring a secure and compact box beam joint.

[0080] On the other hand, this perimeter channel has the additional function of allowing one or more spacer blocks to be inserted into said perimeter channel, manufactured based, for example, on the same adhesive used for the adhesive joint, to ensure a joint of constant thickness. The depth, shape and width of the channel depend on the particular case.

[0081] Preferably, the perimeter channel is located in a position close to the inner surface of the longitudinal and closing profiles, but spaced apart from this inner surface by a small end perimeter portion free of structural joint, so that the perimeter channel is located between the first or second seat and the corresponding end perimeter portion of the longitudinal and closing profiles.

[0082] In some embodiments, the perimeter channel of the metal structure may consist of a groove, preferably rectangular or square in cross-section, which is produced by, for example, machining the metal structure around the entire inner perimeter on the first lateral receiving surface of the joint, on the second lateral receiving surface of the joint or on both lateral receiving surfaces.

[0083] In some embodiments, the box beam further comprises at least one crossmember arranged between two profiles of the metal structure, wherein the at least one crossmember is configured for reinforcement against impacts such as a vehicle impact, and wherein preferably the first glass plate is further attached to a first surface of the at least one crossmember by means of a first structural and gastight joint; and the second glass plate is further attached to a second surface of the at least one crossmember by means of a second structural and gastight joint.

[0084] Thus, the at least one crossmember can be between two longitudinal profiles, between two closing profiles or between a longitudinal profile and a closing profile. Advantageously, the at least one crossmember makes it possible to increase the resistance of the box beam against possible impacts from the outside, for example the impact of a vehicle against the box beam, and / or to provide an aesthetic function. In a preferred embodiment, the at least one crossmember is also fixed, like the profiles of the metal structure, by means of a first structural and gastight adhesive joint to the first glass plate and by means of a second structural and gastight adhesive joint to the second glass plate. In a preferred embodiment, the at least one crossmember is made of the same metal as the longitudinal and closing profiles and is connected solidly to the closed metal structure of the box beam, preferably by welding the two ends of the crossmember to the metal structure, the metal structure with the at least one crossmember forming a compact structure. Thus, for example, in the event of an intentional collision of a moving vehicle against the box beam, the metal crossmember transmits the energy remaining after the energy absorbed by the breakage of the glass plates to the longitudinal profiles or the closing profiles of the box beam, which still continues to function as a connected unit with the broken glass plates. In a particular embodiment of the box beam where one or both glass plates are configured by a laminate of heat-strengthened glass, said laminate of one or both glass plates maintains its geometric position even if it is fractured and is capable of transmitting compressions in one side of the glass laminate and tensions in the intermediate adhesive layer thus remaining bearing capacity to withstand the energy of the impact without collapsing.

[0085] In a preferred embodiment, the at least one crossmember is of the same cross-section as the longitudinal and closing profiles of the box beam metal structure. In some embodiments, the at least one crossmember may comprise a cross-section with two channels spaced apart at each seat on each lateral surface to prevent adhesive overflow into the inner chamber of the box beam.

[0086] In a preferred embodiment, the at least one crossmember is arranged parallel to one or another of the profiles of the closed metal structure and at a certain distance from said profiles, for example the at least one crossmember being arranged at a distance of between 0.4 m and 1 m from the profile of the metal structure closest to the ground when the box beam is placed in a vertical position, for example on a building facade. In other embodiments, the box beam comprises two or more crossmembers attached to the metal structure.

[0087] Preferably the first, the second or both glass plates include an opaque coating in a region at least occupying the interior bounded by the projection of the crossmember on the glass plate, where the projection is according to the direction perpendicular to said glass plate, and said opaque coating will exceed by approximately two millimetres the width of the lateral surface of the crossmember on which the structural joint is applied.

[0088] In an embodiment, the at least one crossmember incorporates one or more perforations adapted to communicate the inner sub-chambers formed when the crossmember divides the box beam chamber. In this way, a substantially equal gas pressure is maintained in the various inner sub-chambers.

[0089] In an embodiment, the box beam further comprises one or more support seats, wherein the one or more support seats are in a part of the first glass plate and / or in a part of the second glass plate, such that the support seats are adapted to provide stability to the box beam against external actions when the box beam is supported in a working position on a surface.

[0090] The support seats have the function of supporting one or both of the glass plates of the box beam in a punctual or continuous manner and thus provide mechanical stability to the box beam against external actions, such as self-weight and wind actions. When there are a plurality of support seats, the plurality of seats are distributed at different specific positions of the glass plates, spaced apart from each other.

[0091] In an embodiment, the box beam further comprises a waterproof tape or band, preferably on the outer perimeter surface of the box beam, preferably covering part or all of the thickness of the perimeter structural joint, to protect the inner chamber against the ingress of moisture through the structural joint thus acting as a waterproof barrier. Such waterproof tape or band may be an aluminium film or other equivalent metal. The waterproof tape or band may be self-adhesive on one side to adhere directly to the outer perimeter surface of the box beam.

[0092] In an embodiment, the box beam is configured as a fixed module, for example a facade enclosure. In other embodiments, the box beam can be configured as a movable module, for example an entrance door to a building.

[0093] In an embodiment, the box beam further comprises information generating elements, energy generating elements, solar radiation control elements and / or security elements. In relation to the energy generating elements, in a specific embodiment, the box beam comprises photovoltaic cells in the first and / or second glass plates, for example the photovoltaic cells may be encapsulated within the intermediate adhesive layer between glass sheets when the first and / or second glass plate is a laminate.

[0094] In an embodiment, the chamber is gastight.

[0095] In an embodiment, the gas contained within the chamber is an inert gas or carbon dioxide, where preferably the inert gas is selected from one of the following: nitrogen, argon, krypton, xenon or a mixture of any of these.

[0096] Each of the elements in the above list of inert gases has a higher thermal insulation than the previous one. As an example, the gas inside the chamber is argon, krypton or xenon, with thermal conductivities (at room temperature) of around 0.016, 0.009 and 0.005 W / m-K respectively, each of them providing superior thermal insulation to the box beam. Depending on the specific thermal insulation requirements of the box beam, one or the other inert gas is chosen, preferably from the above list. In this way, the box beam can be customised by the client to the specific specifications of, for example, the facade where it will be installed, since at any time during the service life of the box beam it is possible to replace the gas in the chamber with another gas with the specific thermal insulation performance of interest.

[0097] In an embodiment, the chamber further comprises at least one closed-loop circuit fluidic connection with an external reservoir, the reservoir adapted to compensate for variations in gas pressure inside the chamber with respect to atmospheric pressure.

[0098] Preferably, the said external reservoir is a pressurised reservoir. By providing at least one fluidic connection to the external reservoir, it is possible, for example, to ensure that the box beam chamber has at all times an internal pressure equal to or close to the atmospheric pressure outside the box beam, which is desirable for its optimal operation and ensures that it remains operational indefinitely with minimum maintenance of its various components.

[0099] In a second inventive aspect, the invention provides a system, comprising the box beam according to any of the embodiments described above and further comprising: means for compensating the pressure variations of the gas contained within the box beam chamber, wherein the means for compensating the gas pressure within the chamber comprise the following elements connected, in an operational mode, in a closed-loop circuit with the interior of the chamber: a pressurised reservoir, which in operational mode comprises a gas at a pressure above atmospheric pressure, wherein the box beam is connected to the pressurised reservoir by means of a first fluidic connection and a second fluidic connection, wherein: the first fluidic connection between the pressurised reservoir and the chamber is configured to allow gas from the pressurised reservoir to enter the chamber, with the interposition of a first solenoid valve to regulate the introduction of gas from the pressurised reservoir into the chamber, and the second fluidic connection between the pressurised reservoir and the chamber is configured to allow gas to flow out of the chamber into the pressurised reservoir, with the interposition of a compressor; at least one relative pressure sensor configured to measure the pressure imbalance between the pressure inside the box beam chamber and the atmospheric pressure; control means in communication with the relative pressure sensor adapted to, depending on the pressure differential value between the chamber and the atmospheric pressure received from the relative pressure sensor, command: the opening of the first solenoid valve of the first fluidic connection, in case the differential value between the pressure inside the box beam chamber and the atmospheric pressure is lower than a predetermined threshold value, or the activation of the compressor of the second fluidic connection, if the difference between the pressure inside the box beam chamber and the atmospheric pressure exceeds a predetermined threshold value.

[0100] The pressures inside (in the gastight chamber of the box beam) and outside (in the atmosphere) have a tendency to decompensate due to fluctuations in atmospheric pressure and gas temperature inside the chamber induced by climatic actions (squalls and anticyclones) and solar radiation. Consequently, in the absence of a pressure compensation system, this pressure difference can reach high values on a daily basis, for example ±10 mbar, generating unwanted mechanical stresses and possible creep and fatigue in the existing adhesive joint between glass plates and metal structure. The present invention of the box beam comprises a pressure compensation system to advantageously equalise the pressure of the gas in the inner chamber preferably with respect to the pressure of the outside atmosphere.

[0101] The pressure compensation system is compact, gastight and external to the box beam and is pneumatically connected, in a closed-loop circuit, to the inner chamber of the box beam by means of one or more valves. It is indicated that the circuit is closed according to an operating mode because the system allows, for example, refilling the gas system when such a refilling operation is necessary due to losses. The most common operating mode where the circuit is closed is the mode where the system is continuously or almost continuously operating to compensate the pressure inside the chamber. The pressure compensation system limits the maximum difference between the outside atmospheric air pressure and the gas pressure of the inner chamber to for example ±1 mbar and consequently prevents the creep and fatigue of the material of the joints and thus extends the life of the first and second joints indefinitely. This is achieved by injecting gas into the chamber in case of underpressure (via the gas inlet valve), or removing gas from the chamber in case of overpressure (via the gas outlet valve). It should be noted that the pressure compensation system is not intended to compensate for pressure differentials caused by short-term dynamic actions (for example wind).

[0102] The various components of the means for compensating the pressure of the gas inside the box beam chamber of the system configure a pneumatic line which is closed at both ends against the inner chamber, thus creating a closed-loop, gastight circuit when the system is operating in an operational mode. The closed-loop, gastight gas circuit is filled with the same gas. The ends of this pneumatic line are the gas inlet and outlet points of the chamber, and between them are at least the pressurised gas reservoir, at least a first solenoid valve and a compressor. A relative pressure sensor measures the pressure difference between the inner chamber of the box beam and the atmospheric pressure outside the box beam. In an embodiment, the gas pressure compensation means, controlled from the control means, limits the maximum difference between pressures inside and outside the box beam to a very small value equal to ± 1 mbar.

[0103] The system according to the second inventive aspect operates in the manner described below.

[0104] In the event that the means of control detect a situation of underpressure inside the box beam chamber with respect to the outside atmosphere, i.e. the difference between the pressure inside the box beam chamber and the atmospheric pressure measured by the relative pressure sensor is lowerthan a threshold value, for example -1 mbar, the means of control automatically activate the solenoid valve of the first fluidic connection, which opens automatically and the higher pressure gas contained in the pressurised reservoir is injected through the first fluidic connection in the direction of the box beam chamber. The first solenoid valve is open until the inside and outside pressures are completely equalised or until a predefined differential pressure threshold value is reached which is considered acceptable, for example ± 0.5 mbar. This pressure equalisation can be achieved for example by a single opening or a pulsed opening of the first solenoid valve, i.e. a sequence of consecutive openings and closings, and where the opening time is predefined and commanded from the control means.

[0105] In the opposite case, i.e. when the means of control detect a situation of overpressure inside the chamber with respect to the outside atmosphere, i.e. when the difference between the pressure inside the box beam chamber and the atmospheric pressure measured by the relative pressure sensor is greater than a threshold value, for example +1 mbar, the means of control automatically activate the compressor of the second fluidic connection, which sucks gas from the box beam chamber and this gas flows through the second fluidic connection in the direction of the pressurised reservoir where it is stored. The compressor is active until the inside and outside pressures are completely equalised or until a predefined and acceptable differential pressure threshold value, for example ± 0.5 mbar, is reached. This pressure equalisation can be achieved for example by a single or pulsed activation of the compressor, i.e. a sequence of consecutive activations and stops, and where the activation time is predefined and commanded from the control means.

[0106] Thus, the closed-loop circuit pressure compensation system according to the second inventive aspect makes it possible to reduce the overpressure and underpressure, with respect to atmospheric pressure, of the box beam chamber by means of an optimal gas exchange between the inside of the box beam chamber and the pressurised reservoir. This makes it possible, on the one hand, to eliminate the effects of cyclic actions of climatic origin on the adhesive joint, and therefore avoids mechanical fatigue in the adhesive and thus indefinitely extends its service life.

[0107] Finally, the system according to the second inventive aspect is configured to allow the circuit and the box beam chamber to be filled with the desired gas for each different application, and also to be able to replace this gas with another gas during the service life if new thermal insulation or other physical performance is required. In a preferred embodiment, the gas contained within the chamber and the means for compensating the gas pressure is a dry inert gas (dry gas being understood as a gas that does not contain water), preferably a dry inert gas of high density, and more preferably a dry inert gas selected from one of the following: nitrogen, argon, krypton, xenon or a mixture of any of them. In another preferred embodiment, the dry gas contained within the chamber and gas pressure compensation means is carbon dioxide.

[0108] On the other hand, as the inner chamber of the box beam and the pressure compensation circuit are gastight, and the filling gas is dry, the risk of condensation is eliminated and this makes it possible to dispense with desiccant material inside the box beam cavity. By not requiring desiccant material in the inner chamber of the box beam, there is a saving in terms of materials, for example compared to traditional double- glazed insulating units.

[0109] In a preferred embodiment, the pressurised reservoir is adapted to safely store a gas at high pressure, preferably up to several tens of bars, for example up to 40 bar pressure. The pressurised reservoir is dimensioned so that it can safely store the excess gas in the inner chamber between the climatic scenarios that would generate the maximum and minimum pressure in the inner chamber in the absence of pressure compensation means. In an embodiment, the pressurised reservoir is fixed to an external part of the box beam, although other locations are possible.

[0110] In an embodiment, the compressor is an electronically driven hermetic piston compressor. In an embodiment, the control means is a controller, preferably a programmable logic controller (PLC).

[0111] In an embodiment, the relative pressure sensor may be a relative pressure transducer.

[0112] Optionally, the system may further comprise other sensors, such as one or more absolute pressure sensors. In an embodiment, the system further comprises a first absolute pressure sensor of the pressurised reservoir, for example a pressure transducer. This absolute pressure sensor of the pressurised reservoir, preferably connected to the inlet or outlet of the pressurised reservoir, is furthermore connected to the control means, so that in case this absolute pressure sensor measures an excessive pressure, the control means command the opening of a safety valve of the pressurised reservoir to vent gas to the atmosphere and thus relax the pressures of the pressurised reservoir. This absolute pressure sensor of the pressurised reservoir therefore adds further structural safety to the pressurised reservoir. In an embodiment, the system further comprises a second absolute pressure sensor for measuring atmospheric pressure. The pressure value measured by the second absolute pressure sensor, combined with the pressure values provided by the relative pressure sensor and the first absolute pressure sensor, makes it possible to verify the absence of leaks and the correct functioning of the gas pressure compensation means inside the box beam chamber.

[0113] In an embodiment, the system further comprises a first non-return valve in the second fluidic connection, located between the compressor and the chamber, wherein said first non-return valve is oriented to allow the gas to exit the chamber.

[0114] In addition, this non-return valve protects against backflow, i.e. this first non-return valve allows gas to flow from the box beam chamber to the compressor and the pressurised reservoir, but prevents gas flow in the opposite direction.

[0115] In an embodiment, the system further comprises a second non-return valve in the second fluidic connection, located between the compressor and the pressurised reservoir, wherein said second non-return valve is oriented to allow gas to flow from the compressor to the pressurised reservoir.

[0116] This means that the second non-return valve allows gas flow from the compressor to the pressurised reservoir but prevents gas flow in the opposite direction.

[0117] In an embodiment, the means for compensating the gas pressure inside the chamber further comprises in the second fluidic connection: a second three-way solenoid valve between the compressor and the pressurised reservoir, and a second reservoir between the compressor and the first non-return valve, wherein the second solenoid valve is further connected to the second reservoir via a third fluidic connection, wherein the third fluidic connection is configured to allow gas to exit from the second fluidic connection where the second solenoid valve is located into the second reservoir; and where the control means are additionally adapted to, after the compressor stops, command: the opening of the second solenoid valve of the second fluidic connection, to open the gas passage to the third fluidic connection to the second reservoir, e ualising the pressure at the inlet and outlet of the compressor.

[0118] The second three-way solenoid valve is adapted to allow gas flow from the compressor to the pressurised reservoir (when the compressor is running) and alternatively, from the compressor to the second reservoir (when the compressor is stopped) in order to dissipate the high pressures in the compressor outlet section (section between the compressor and the second solenoid valve) into the second reservoir.

[0119] The second reservoir has dimensions to store, at the moment the compressors stops, at near-atmospheric pressure the pressurised gas stored in the section between the compressor and the second solenoid valve, thus maintaining pressures close to atmospheric pressure in the vicinity of the compressor (both at its inlet and outlet), which allows it to start without pneumatic resistance when required. In an embodiment, the second reservoir may be a widening of the conduit itself. In an embodiment, the second reservoir is fixed to an external part of the box beam, although other locations are possible.

[0120] In an embodiment, the means for compensating the gas pressure inside the chamber further comprises a throttle section in the first fluidic connection to reduce at least the gas inlet flow rate into the chamber from the pressurised reservoir, where preferably the throttle section is interposed between the first solenoid valve and the gas inlet point to the box beam chamber.

[0121] In a particular embodiment, the throttle section in the first fluidic connection is configured to reduce the flow rate and inlet pressure of gas into the chamber from the pressurised reservoir.

[0122] In a preferred embodiment, the means for compensating the gas pressure inside the chamber are individual for each box beam. In other embodiments, means for compensating the gas pressure inside the chamber are shared by several box beams.

[0123] In a particular embodiment of the system, the gas inlet point and the gas outlet point of the chamber are positioned at a different height. This configuration with different heights serves to facilitate the recirculation of the gas within the system.

[0124] It is observed that, in an operational mode, e.g. when the box beam is installed in a building facade, the temperatures inside the chamber of the box beam have a tendency to vary due to the daily fluctuations of atmospheric temperature and solar radiation. Consequently, it is observed that the temperature in the chamber of the box beam can reach values for example of around 50°C on hot summer days and around 10°C on cold winter days. These extreme values (around 50°C and around 10°C) deviate notably from the comfort temperature fora person inside a building, which is around 20°C. As a result, a significant and undesired heat transfer occurs across the box beam, which provides low thermal insulation to the building.

[0125] In order to overcome these drawbacks, in an embodiment, the system according to the second inventive aspect further comprises, in addition to at least the elements of the system according to the second inventive aspect, means for mitigating the heat transfer through the chamber of the box beam by controlling the temperature of said chamber thereby reducing the impact of temperature fluctuations.

[0126] In particular, in an embodiment, the system according to the second inventive aspect further comprises: a first temperature sensor located in the pressurized reservoir, and a second temperature sensor located in the chamber of the box beam; wherein the control means are further in communication with the first and second temperature sensors, and further adapted to act according to a heat exchanging mode of operation between the chamber and the pressurized reservoir comprising: either activating the introduction of gas into the chamber by transferring gas from the pressurized reservoir into the chamber, or activating the extraction of gas from the chamber by transferring gas from the chamber to the pressurized reservoir, or,

[0127] - simultaneously activating both of the above; and wherein the control means is further adapted to activate the heat exchanging mode of operation between the chamber and the pressurized reservoir when: i) the absolute value of the temperature difference between the measurement of the first temperature sensor and the measurement of the second temperature sensor exceeds a predetermined threshold value; or ii) the difference between the measurement of the second temperature sensor and a first reference value is higher than a predetermined threshold value, when the measurement of the second temperature sensor is higher than said first reference value; or

[0128] Hi) the difference between a second reference value and the measurement of the second temperature sensor is higher than a predetermined threshold value, when the measurement of the second temperature sensor is lower than said second reference value.

[0129] In other words, the control means of the system comprising means for mitigating the heat transfer through the chamber of the box beam, command at least the opening of the first solenoid valve of the first fluidic connection, thereby allowing gas from the pressurised reservoir to enter the chamber; and at least the activation of the compressor of the second fluidic connection to extract gas from the chamber and store it inside the pressurised reservoir, and these gas movements take place respecting the thresholds of pressure equalisation.

[0130] The system comprising means for mitigating the heat transfer through the chamber of the box beam advantageously increases the thermal insulation of the box beam by controlling the temperature of the chamber and mitigating the temperature variations in the chamber of the box beam. This effect is achieved by advantageously controlling the temperature of the gas inside the chamber and approximating it to the temperature of the gas inside the pressurized reservoir. The pressurized reservoir is maintained in a set temperature range. In a preferred embodiment, this set temperature range is close to the comfort temperature for a person, which is between 15°C and 25°C. The system comprising means for mitigating the heat transfer through the chamber of the box beam makes use of the same elements as the pressure compensation system, with the difference that it additionally uses a first temperature sensor located in the pressurized reservoir for measuring the temperature of the gas inside the pressurised reservoir and a second temperature sensor located in the chamber of the box beam for measuring the temperature at one point inside the chamber of the box beam.

[0131] In the embodiment of the system comprising means for mitigating the heat transfer through the chamber of the box beam: activating the introduction of gas into the chamber by transferring gas from the pressurized reservoir into the chamber is at least opening the first solenoid valve of the first fluidic connection; and activating the extraction of gas from the chamber by transferring gas from the chamber to the pressurized reservoir is at least activating the compressor of the second fluidic connection.

[0132] In a particular embodiment of the system comprising means for mitigating the heat transfer through the chamber of the box beam, the reference value is a measurement of the temperature of a zone protected by the box beam. To provide an example, the zone protected by the box beam may be the interior of a building, provided that the box beam is installed as part of the facade of a building. In alternative embodiments, the reference value is a predetermined value.

[0133] In some embodiments, the first reference value of condition ii) and the second reference value of condition iii) are identical, for example in the previous case wherein the reference value is a measurement of the temperature of a zone protected by the box beam.

[0134] In other embodiments, said first and second reference values are distinct one from one another. This is exemplified by cases where the first and second reference values are a predetermined value. To illustrate, in an embodiment, the first reference value may be ranged from 20°C to 30°C, preferably 25°C; and the second reference value may be ranged from 10°C to 20°C, preferably 15°C.

[0135] In one particular embodiment of the system comprising means for mitigating the heat transfer through the chamber of the box beam, the activation of the gas introduction into the chamber in the heat exchanging operation mode is automatically activated when the pressure difference between the inside and the outside of the chamber drops below a predetermined pressure threshold value; and / or the activation of gas extraction in the chamber in the heat exchanging operation mode is automatically activated when the pressure difference between the inside and the outside of the chamber rises above a predetermined pressure threshold value.

[0136] The inventors observed that the gas within the chamber of the box beam stratified and that a temperature gradient existed between the top and bottom parts of the chamber. For this reason, in an embodiment, at least two temperature sensors are arranged at different locations within the chamber of the box beam, for example, one in a top part and one in a bottom part that was opposed to the top.

[0137] For this reason, in a particular embodiment of the system comprising means for mitigating the heat transfer through the chamber of the box beam, the system further comprises a third temperature sensor located in the chamber; and wherein one sensor, selected from the second temperature sensor or the third temperature sensor, is located in a lower part of the chamber according to the direction of gravity action when the chamber is in an operating position and, the other temperature sensor, selected from the second temperature sensor or the third temperature sensor, is located in a higher part of the chamber, above the previous one sensor; and optionally wherein the control means are further adapted to activate the heat exchanging mode of operation when the absolute value of the difference of temperature measurements obtained at the second temperature sensor and the third temperature sensor are above a predetermined threshold value.

[0138] In a particular embodiment of the system, comprising means for mitigating the heat transfer through the chamber of the box beam and comprising a third temperature sensor located in the chamber, the gas inlet point and the gas outlet point of the chamber are positioned at a different height. This distinct height arrangement serves to facilitate the recirculation of the gas within the chamber.

[0139] In an operating mode, the system according to this embodiment recirculates the gas inside the closed-loop circuit by removing gas from the chamber of the box beam and exchanging it by gas from the pressurised reservoir.

[0140] In a first mode of operation, the control means of the system are adapted to activate the heat exchanging mode of operation between the chamber and the pressurized reservoir only at certain times. In this first mode of operation, the control means of the system activate the heat exchanging mode of operation when at least one of the three conditions i), ii) or iii) is met, and stop when none of these three conditions are met or until the relative pressure sensor detects that a threshold pressure (for example +1 mbar) has been reached.

[0141] In a second mode of operation, the control means of the system are adapted to activate the heat exchanging mode of operation between the chamber and the pressurized reservoir cyclically. In this second mode of operation, the control means are adapted to command the opening of the solenoid valve of the first fluidic connection to let gas from the pressurised reservoir (at a set controlled temperature) enter to the chamber of the box beam (excessively warm or cold) until the relative pressure sensor detects that a threshold pressure (for example +1 mbar) has been reached. At that moment, the control means are adapted to command the closing of the solenoid valve of the first fluidic connection and activating the compressor of the second fluidic connection that sucks gas from the chamber of the box beam and stores it in the pressurised reservoir, until the relative pressure sensor measures a pressure balance, which means that the relative pressure between the inside of the chamber and the outer atmosphere is close to zero (for example ±0.5 mbar). Then the cycle restarts and the solenoid valve opens again, letting gas into the chamber of the box beam until the threshold pressure is reached, then the solenoid valve closes, and the compressor activates to suck gas from the chamber of the box beam until a pressure balance is reached, and the system keeps operating continuously in this way.

[0142] The temperature of the gas within the pressurised reservoir is kept in a set temperature range, for example by positioning the reservoir underground where the thermal conditions are significantly stable (beneath the box beam when this one is positioned vertically as a ground floor facade element).

[0143] In certain circumstances, the temperature of the gas entering to the pressurised reservoir, and coming from the chamber of the box beam in the recirculation process may be either excessively warm or cold. In such cases, in some embodiments, the pressurised reservoir incorporates heat sinks and / or fans for heat exchange with the surroundings with the objective of maintaining the pressurised reservoir within the set temperature range.

[0144] In a third inventive aspect, the invention provides a method of manufacturing the box beam according to any of the embodiments described above, wherein the method of manufacturing makes use of the following elements: a support; a first glass plate, which has an outer surface and an inner surface arranged opposite to the outer surface; a second glass plate, which has an outer surface and an inner surface arranged opposite to the outer surface; two metal longitudinal profiles, extending along a certain longitudinal path, comprising a first lateral receiving surface, with a first seat adapted to receive a perimeter part of the inner surface of the first glass plate and a second lateral receiving surface, arranged opposite to the first lateral surface, with a second seat adapted to receive a perimeter part of the inner surface of the second glass plate, two metal closing profiles, comprising a first lateral receiving surface, with a first seat adapted to receive a perimeter part of the inner surface of the first glass plate, and a second lateral receiving surface, arranged opposite to the first lateral surface, with a second seat adapted to receive a perimeter part of the inner surface of the second glass plate; wherein the method of manufacturing the box beam comprises the steps of: rest the outer surface of the first glass plate on the support; connect the two longitudinal profiles with the two closing profiles to form a closed metal structure, bond the metal structure to the first glass plate by means of a first joint formed by the provision of a first adhesive bead, provide for a second joint formed by the provision a second adhesive bead on at least a portion of the second lateral surface of the metal structure, bring the inner surface of the second glass plate into contact with the second lateral surface of the metal frame provided with the second adhesive bead, to bond the metal structure to the second glass plate, so as to obtain the assembled box beam,

[0145] - filling of the box beam chamber with a dry gas. The aforementioned stages of the method of manufacture according to the third inventive aspect are preferably carried out in the order indicated above.

[0146] The support on which the outer surface of the first glass plate rests can be, for example, an assembly table or similar. Preferably, the assembly of the different elements of the method is carried out in a horizontal position, i.e. with the glass plates and the metal structure sensibly parallel to the floor of the room or workshop where this assembly is carried out.

[0147] In some embodiments, the step of bonding the metal structure to the first glass plate by means of a first joint formed by a first adhesive bead is according to an option a) or an option b), where option a) comprises the sub-stages of: al) provide a first adhesive bead on at least a portion near or touching the perimeter edge of the inner surface of the first glass plate, and a2) bring the first lateral surface of the metal structure into contact with the inner surface of the first glass plate provided with the first adhesive bead, to bond the metal structure to the first glass plate, where option b) comprises the sub-stages of: bl) rest the second lateral surface of the metal structure on the inner surface of the first glass plate on the support, b2) provide a first adhesive bead on at least a portion of the first lateral surface of the metal structure, and b3) position the metal frame with the first adhesive bead facing the inner surface of the first glass plate and bring the first lateral surface of the metal structure with the first adhesive bead into contact with the inner surface of the first glass plate, in order to bond the metal frame to the first glass plate.

[0148] In some embodiments, the dosing of the first and / or second bead of adhesive at the stages of providing the first and second joints can be performed by automatic dosing means, for example by a Cartesian robot incorporating an adhesive dosing valve that moves according to the three spatial coordinates, and where a hose supplies adhesive to the valve from a drum filled with adhesive and pressurised by a compressor. In this example, the drum can be mobile and accompany the Cartesian robot in its movements, and the dosing valve is adapted to move along the perimeter of the glass plate and / or metal structure on which it deposits the adhesive bead. Automatic control means are used to control the movements of the robot, the trajectory of the dosing valve, the opening and closing of the dosing valve, the flow rate of adhesive dosed by the dosing valve and the movement of the adhesive drum.

[0149] In some embodiments, steps a2) and / or b3) comprise a sub-step of approaching the metal structure before making contact and bonding with the first glass plate in which the metal structure is suspended in the air in a horizontal position over the support, for example by means of straps and a bridge crane. The metal structure, in its central axis, can optionally incorporate during the assembly process an auxiliary bar that crosses it longitudinally and where this auxiliary bar comprises Teflon pieces as spacers between the first and second glass plates to ensure that the second glass plate does not deform appreciably under its own weight. The Teflon parts of this auxiliary bar provide additional support for the second glass plate and thus minimise its deformation. In the final part of this sub-stage of approaching the metal structure to the first glass plate, a system of wedges and / or positioners can be used for an optimal final approach of the metal structure, until the contact of the first lateral surface of the metal structure with the inner surface of the first glass plate is made.

[0150] In some embodiments, the step of bringing the inner surface of the second glass plate into contact with the opposite lateral surface of the metal structure provided with the second joint, once the metal structure is bonded to the first glass plate, to bond the metal structure to the second glass plate, comprises a sub-step of positioning the second glass plate in proximity to the metal structure but without making contact. This substage of approaching the second glass plate before making contact can be carried out by bringing the second glass plate in a horizontal position and with the lower surface facing the surface of the metal structure provided with the second adhesive bead, for example, by means of a system of suction cups adapted to hook at different points on the surface of the second glass plate and to hold these suction cups with automatic or semi-automatic means of displacement such as a bridge crane.

[0151] In the final part of this sub-stage of approaching the second glass plate to the metal structure provided with the second adhesive bead, a wedge system can be used for the final approach until the second lateral surface of the metal structure contacts the inner surface of the second glass plate.

[0152] Preferably, the perimeter channels of the metal structure are equipped with spacers to ensure a controlled thickness, around 1 mm, of the adhesive joint after contact is made between the metal structure and the corresponding glass plate, and thus prevent the weight of these components from excessively crushing the adhesive joint, which would negatively contribute to promoting adhesive overflow into the inner chamber.

[0153] The method of manufacture according to the third inventive aspect advantageously allows to obtain a box beam with a first and second perimeter adhesive layer of constant width and thickness along all the joints, which gives the box beam optimal mechanical properties of stiffness, strength and high durability. In addition, the manufacturing method ensures parallelism between glass plates which provides high optical quality by avoiding optical distortions and ensuring transparency.

[0154] In a particular embodiment, the dry gas from the chamber filling stage is selected from: an inert gas, preferably selected from one of the following: nitrogen, argon, krypton, xenon or a mixture of any of these; or carbon dioxide.

[0155] In a particular embodiment, prior to the stage of filling the box beam chamber with a dry gas, it further comprises the stage of: purging of the moist air from the box beam chamber.

[0156] In a particular embodiment, after the step of bringing the inner surface of the second glass plate into contact with the second lateral surface of the metal structure provided with the second adhesive bead for bonding the metal structure to the second glass plate, the method described above further comprises the additional step of: heat curing of the first and second box beam adhesive bead, and cooling of the assembled and cured box beam.

[0157] Depending on the structural adhesive used for the first and second adhesive beads, for example if a one-component epoxy adhesive is chosen, it may be necessary or desirable to include a heat curing stage of the adhesive to maximise the mechanical and physical properties of the adhesive joints, such as strength, stiffness and gastightness. The heat curing stage is followed by a cooling stage until the box beam reaches the ambient temperature of the room or workshop where it is being manufactured. In a particular embodiment of when the stages of heat curing the first and second box beam adhesive bead and cooling the assembled and cured box beam are included in the method, the stage of heat curing the first and second box beam adhesive bead is performed by placing the assembled box beam inside an oven, preferably by resting the box beam on a support and in a horizontal position, and preferably at a temperature between 80 and 120 °C for a time between 0.5 to 4 hours.

[0158] Optionally, the heat curing stage of the first and second adhesive joints of the box beam once it is assembled is performed by positioning both the assembled box beam and the support on which the box beam was supported during the assembly stages inside an oven. In an embodiment, the curing temperature inside the oven is reached by a gentle ramp of temperature increase, which allows to avoid thermal stresses in the box beam.

[0159] Advantageously, the heat curing stage of the first and second adhesive beads of the box beam once assembled inside an oven, at a given temperature and for a given period of time, which will depend on the specific characteristics of the structural adhesive, allows for optimal cross-linking of the adhesive and structural integrity between the first and second glass plates and the metal structure. Furthermore, advantageously, inside the oven the entire box beam reaches a very homogeneous temperature so that its components expand in a very similar way and consequently no significant residual stresses of thermal origin are generated in the materials during the curing stage.

[0160] In a particular embodiment of when the stages of heat curing of the first and second box beam adhesive bead and cooling of the assembled and cured box beam are included in the method, the cooling stage of the assembled and cured box beam consists of a slow cooling of the assembled and cured box beam by allowing hot air to escape from inside the oven.

[0161] Preferably, this slow cooling of the assembled and cured box beam is by partial opening of the oven, so that the temperature decreases gradually and similarly among all its components, and so that consequently no significant residual stresses of thermal origin are generated in the materials during the cooling stage. The cooling is carried out slowly until the entire box beam reaches the temperature of the room or workshop where it is manufactured. In alternative embodiments, where the stages of heat curing of the first and second box beam adhesive bead and cooling of the assembled and cured box beam are included in the method, the cooling stage of the assembled and cured box beam consists of a more rapid cooling down to room temperature by removing the box beam from inside the oven. The two types of cooling of the box beam can be combined with each other, for example, first by a first slow cooling sub-stage of the assembled and cured box beam inside the oven and then by a second fast cooling sub-stage at room temperature.

[0162] In a particular embodiment, the step of, before the step of joining the two metal longitudinal profiles with the two metal closing profiles forming a closed metal structure, is added to the method described above: machine the first and / or second lateral surfaces of the two longitudinal profiles and the two metal closing profiles with a perimeter channel.

[0163] This perimeter channel(s) ensures a structural adhesive joint of significantly constant thickness, for example by inserting spacers inside the channel, and additionally drastically reduces the risk of adhesive overflow into the chamber between glass plates during the manufacturing process, since said channel has the function of a receptacle to stop the advance of the adhesive towards the chamber.

[0164] In a particular embodiment, prior to the steps of bonding the metal structure to the first glass plate by means of a first joint and providing a second joint, the method of manufacturing the box beam further comprises the step of: apply a primer layer as corrosion protection and / or adhesion promoter on the surfaces of the metal structure and on the surfaces of the first and second glass plates to be bonded by the first and second adhesive bead.

[0165] In a particular embodiment, prior to the steps of bonding the metal structure to the first glass plate by means of a first joint and of providing a second joint, the method of manufacturing the box beam further comprises the step of arranging a plurality of spacers, preferably inserted at different positions in the perimeter channels, between the metal structure and each glass plate, wherein the plurality of spacers are preferably configured as blocks, preferably made of a cured adhesive, and more preferably of the same adhesive as the first and second adhesive bead.

[0166] In those cases where the metal frame incorporates at least one crossmember inscribed within the perimeter of the frame, the at least one crossmember is also adhesively- bonded to the glass plates during one stage of the manufacturing method. Thus, the corresponding adhesive beads, which receive the glass plate and / or frame, are also applied following the path of the crossmembers. In some embodiments, the at least one crossmember, like the other profiles, incorporates channels as a receptacle to stop the advance of the adhesive towards the chamber, i.e. the cross-section of the at least one crossmember has two channels spaced apart at each seat on each lateral surface to prevent the adhesive from overflowing into the inner chamber of the box beam.

[0167] In an embodiment of the method, the step of joining the two longitudinal profiles with the two closing profiles to form the closed metal structure is performed by welding.

[0168] The step of filling the box beam chamber with a dry gas is a final step of the method after the box beam has been manufactured. In addition, the method can include the stages of connecting the inside of the chamberto an external circuit, where the chamber and the external circuit configure a closed-loop and gastight circuit assembly filled with the same gas, and where it is inserted in the closed-loop and gastight circuit a pressurised reservoir filled with the same gas, and means of injection and suction of the gas from the chamber. This advantageous system makes it possible to counteract any undesirable pressure variations that may occur inside the box beam chamber during the service life of the box beam once it is installed, for example due to solar radiation and climatic actions (squalls and anticyclones) that affect the box beam.

[0169] DESCRIPTION OF THE DRAWINGS

[0170] These and other features and advantages of the invention will become clearer from the following detailed description of a preferred embodiment, given by way of illustrative and non-limiting example only, with reference to the accompanying figures.

[0171] Figure 1 This figure shows a front view of an example of the box beam.

[0172] Figure 2 This figure shows a rearview of the same example of the box beam shown in figure 1.

[0173] Figure 3 This figure shows a partial view of the box beam in cross-section along line A-A' in figure 1. Figure 4 This figure shows a detail of figure 3.

[0174] Figure 5 This figure shows a front view of the metal structure according to the same example of the box beam of figure 1.

[0175] Figure 6 This figure shows a front view of the metal structure according to another example of the box beam.

[0176] Figure 7 This figure shows a schematic view of the various elements that configure an embodiment of the means for compensating the gas pressure inside the box beam chamber.

[0177] Figure 8 This figure shows a schematic view of the various elements that configure one embodiment of the means for mitigating the heat transfer through the chamber of the box beam.

[0178] Figure 9 This figure shows a schematic view of the various elements that configure another embodiment of the means for mitigating the heat transfer through the chamber of the box beam.

[0179] DETAILED ACCOUNT OF THE INVENTION

[0180] As a person skilled in the art will appreciate, aspects of the present invention may take the form of a box beam (10), a system comprising the box beam (10) and means for compensating pressure variations within the box beam chamber, and a method for manufacturing the box beam (10).

[0181] The present invention, according to the first inventive aspect, is a box beam (10), preferably suitable to be installed as a structure or enclosure in a building, for example on a facade or also as a transparent floor or roof of a part of a building.

[0182] An example of an embodiment of the box beam (10), according to a first aspect of the invention, is illustrated in Figures 1 to 4 and is shown from the front and rear in Figures 1 and 2, respectively. In them it can be seen that the box beam (10) comprises a first glass plate (1), which has an outer surface (1.1) and an inner surface (1.2) arranged opposite to the outer surface (1.1); and a second glass plate (2), which has an outer surface (2.1) and an inner surface (2.2) arranged opposite to the outer surface (2.1), wherein the second glass plate (2) is arranged parallel to the first glass plate (1) and spaced apart from said first glass plate (1), see Figure 3. In this example of an embodiment of the box beam (10) shown in the figures, both glass plates (1, 2) extend along a longitudinal direction and a direction transverse to the longitudinal direction, presenting the same rectangular shape and the same dimensions of length (longitudinal direction) and width (direction transverse to the longitudinal direction), as well as the same thickness (el, e2) (see Figure 3). The thickness (el, e2) of both glass plates (1, 2) need not always be the same, as it will depend on the specific needs of each box beam (10).

[0183] The box beam (10) comprises, in addition to the glass plates (1, 2), a metal perimeter structure (3), as a frame, interposed between the inner surface (1.2) of the first glass plate (1) and the inner surface (2.2) of the second glass plate (2), see Figure 3, where the metal structure (3) acts as a spacer between the two glass plates (1, 2).

[0184] Figure 1 shows the rectangular outer surface (1.1) of the first glass plate (1), while Figure 2, which illustrates the same box beam (10) but viewed from the rear, shows the rectangular outer surface (2.1) of the second glass plate (1). In both Figures 1 and 2, the perimeter metal structure (3) is shown in a dashed line. A user looking at the front and back of the box beam (10) can see an inner part of the box beam since the first and second glass plates (1, 2) arranged on the front and rear faces of the box beam (10) are transparent or translucent. In some embodiments, the box beam comprises an opaque coating (9a, 9b) arranged on a surface of a glass sheet of the first and / or a glass sheet of the second glass plate and whose function is to partially or completely hide the joints. In Figures 1 and 2 this opaque coating (9a, 9b) is not shown, but in Figures 3 and 4 it is shown. When looking sideways at the box beam (10) (figure not shown) the user does see a part of the metal structure (3), in particular the outer surface (3.4) around the perimeter. The perimeter metal structure (3) is arranged in the space between the two glass plates (1, 2) which runs along the four perimeter edges of the glass plates (1, 2), forming a closed rectangular perimeter path with a certain thickness.

[0185] Figure 5 shows a front view of only the perimeter metal structure (3) according to the same example of an embodiment of the box beam (10). It can be seen that the perimeter metal structure (3) is formed, in this illustrated example of an embodiment, by two longitudinal profiles (3b, 3d) and two closing profiles (3a, 3c) of shorter length than the longitudinal profiles (3b, 3d), joined at their respective ends, preferably by welding, forming a rigid and compact structure with a rectangular perimeter. Each profile (3a, 3b, 3c, 3d) of the metal structure configures one side of the rectangle and is configured according to the same constant cross-section, in the shape of a rectangle. Figure 3 shows such a rectangle-shaped cross-section of the metal structure (3). In this illustrated example of an embodiment, each profile (3a, 3b, 3c, 3d) of the metal structure (3) is solid.

[0186] As shown in Figure 3, which represents a partial view of the box beam (10) in cross section along line A-A' in Figure 1, the two glass plates (1, 2) are arranged in parallel and spaced apart, so that the respective inner surfaces (1.2, 2.2) of the first and second glass plate (1, 2) face each other, while the respective opposite outer surfaces (1.1, 2.1) of the first and second glass plate (1, 2) face outwards. In this example of an embodiment of the box beam (10) the two glass plates (1, 2) are configured by a laminated plate. In particular, in both cases, the glass plates (1, 2) consist of two glass sheets (la, lb, 2a, 2b) arranged in a stacked arrangement, between which is interposed a thermoplastic adhesive layer (5) that joins the inner surfaces of the two glass sheets (la, lb, 2a, 2b) to each other. In this example of an embodiment illustrated in Figure 3, the two laminated glass plates (1, 2) additionally comprise a respective opaque coating (9a, 9b) arranged on an internal surface of each glass plate (1, 2), and extending along a region on this inner surface at least approximately occupying the interior bounded by the projection of the metal structure (3) on the glass plate (1, 2), wherein the projection is according to the direction perpendicular to said glass plate (1, 2).

[0187] In this same Figure 3, one of the closing profiles (3a) of the metal structure (3) can be seen and that said metal structure (3) acts, among other functions, as a spacer between the two glass plates (1, 2) and completely closes the inner space between glass plates (1, 2), so that this inner space, delimited mainly by the inner surface (3.3) of the metal structure (3) and the respective inner surfaces (1.2, 2.2), in this case rectangular, of the first and second glass plate (2) form the chamber (11). This chamber (11) is gastight and contains a gas.

[0188] In this same Figure 3, it is observed that the larger sides of the rectangular cross section of the profile (3a) of the metal structure (3) correspond to the outer (3.4) and inner (3.3) perimeter surfaces of the metal structure (3), where the outer (3.4) perimeter surface faces outwards, while the inner (3.3) perimeter surface faces the chamber (11). It can also be seen in this same Figure 3 that the smaller sides of the rectangular cross-section of the profile (3a) of the metal structure (3) correspond to the first and second perimeter lateral surfaces (3.1, 3.2). As can be seen in the detail of Figure 4, each first and second perimeter lateral surfaces (3.1, 3.2) (in Figure 4 only the detail of the first lateral surface

[0189] (3.1) of the metal structure with the first glass plate (1) is shown) has a seat (3.1.1, 3.2.1), which corresponds to a part of the respective perimeter lateral surfaces (3.1, 3.2), each seat (3.1.1, 3.2.1) being adapted to contact a respective perimeter joint (4a, 4b), which in the specific case of the example illustrated in Figures 1 and 2, is made by means of an adhesive layer (shown with dots in Figure 3 and in the detail of Figure 4). The first lateral surface (3.1) has a first seat (3.1.1), corresponding to an outermost part of the first lateral surface (3.1), the first seat (3.1.1) being adapted to receive and contact the first perimeter adhesive layer (4a). The second lateral surface (3.2) has a second seat (3.2.1), corresponding to an outermost part of the second lateral surface (3.2), the second seat

[0190] (3.2.1) being adapted to receive and contact the second perimeter adhesive layer (4b).

[0191] In this example of an embodiment illustrated in Figures 1 and 2, the first joint (4a) and the second joint (4b) are by means of a high-strength structural adhesive, preferably a thermally cured epoxy-based adhesive. Preferably, the adhesive layer forming the first joint (4a) and the second joint (4b) has a layer thickness (e4) of about 1 mm (see Figure 4). In Figures 3 and 4 the layer thickness (e4), which has been depicted of the first joint (4a) in Figure 4, is represented schematically, i.e. it is not scaled proportionally with respect to a real example in orderto allow showing and highlighting certain constructive details with respect to others.

[0192] The detail of Figure 4 shows that the first perimeter adhesive layer (4a) covers the entirety of the first seat (3.1.1), leaving an extreme perimeter portion (3.1.2) on the side that touches the chamber (11) with no adhesive layer (4a, 4b). While the detail in Figure 4 corresponds to the first adhesive layer (4a), the same description applies to the second adhesive layer (4b). Between the extreme perimeter portion (3.1.2), free of adhesive layer (4a), and the seat (3.1.1), joined by the adhesive layer (4a) to the inner surface (1.2) of the first glass plate (1), there is a perimeter channel (8a) adapted to receive the excess adhesive (4a) and prevent its entry into the chamber (11). In this case, the first extreme perimeter portion (3.1.2) of the metal structure (3) is at a height (taken in the direction perpendicular to the glass plates (1, 2)) substantially the same as the first seat

[0193] (3.1.1) of the metal structure (3). In this particular illustrated case, the perimeter channel (8a) in cross-section is rectangular in shape. In the detail of Figure 4, it can be seen how a remnant of the adhesive layer (4a) on the innermost side (corresponding to where the chamber (11) is located) has surpassed and is lodged inside the perimeter channel (8a), so that it does not extend towards the extreme perimeter portion (3.1.2), which is free of the adhesive layer (4a). The extreme perimeter portion (3.1.2) is adapted so that it is always free of adhesive layer (4a). The height (p8) and width (a8) of the perimeter channel(s) (8a), both dimensions shown in Figure 4, are determined by the specific specifications of the metal structure (3) suitable for each box beam model (10).

[0194] Thus, the first glass plate (1) is connected to the first seat (3.1.1) of the first lateral surface (3.1) of the metal structure (3) by means of the first joint (4a) and gastight, in this example of an embodiment the first joint (4a) is continuous, preferably in the form of a bead, and runs along the entire first lateral surface (3.1) perimeter of the metal structure (3); and the second glass plate (2) is connected to the second seat (3.2.1) of the second lateral surface (3.2) of the metal structure (3) by means of the second joint (4b) and gastight, in this example of an embodiment the second joint (4b) is continuous, preferably in the form of a bead, and runs preferably along the entire second lateral surface (3.2) perimeter of the metal structure (3). The first and second structural joints (4a, 4b) provide gastightness to the chamber (11) as part of the structural joints (4a, 4b) is in direct contact with the gas inside the chamber (11).

[0195] Figure 5 shows a front view of the metal structure (3) and includes a detail of a corner of said metal structure (3) according to the same example of an embodiment of the box beam (10) of Figures 1 to 4. In this Figure 5, the four profiles (3a, 3b, 3c, 3d) that configure the perimeter metal structure (3) can be seen and in particular the detail of the first perimeter lateral surface (3.1) of the metal structure (3), which has a first portion (3.1.1) located on the outermost part of the metal structure (3) to receive the adhesive layer (4a), then a perimeter channel (8a) and finally, close to the chamber (11) an end portion (3.1.2).

[0196] Figure 6 shows a front view of the metal structure (3) according to another example of the box beam (10). In particular, it shows an embodiment of the metal structure (3) that includes, in addition to the four profiles (3a, 3b, 3c, 3d) that configure the perimeter metal structure (3), a crossmember (24) arranged in this case between the two longitudinal profiles (3b, 3d). This crossmember (24) is designed to reinforce the box beam (10) against possible impacts from the outside, such as the impact of a vehicle, and / or for an aesthetic function. The crossmember (24) is preferably made of the same metal as the rest of the metal structure and is preferably connected to the first and second glass plates (1,2) by means of a first structural and gastight joint and a second structural and gastight joint, respectively (not shown in this Figure 6). Furthermore, the crossmember (24) is solidly joined to the closed metal structure (3) of the box beam (10), preferably by joining the two ends of the crossmember by welding to the metal structure (3), the metal structure plus the crossmember forming a compact assembly. In the embodiment shown in Figure 6, the crossmember (24) has a cross-section substantially the same as that of the rest of the profiles of the metal structure (3) of the box beam

[0197] (10), i.e. rectangular. However, this cross-section has, unlike the cross-sections of the rest of the profiles of the metal structure (3), two channels spaced apart at each seat on each lateral surface, see detail A-A' in Figure 6. The crossmember (24) is arranged parallel to the closing profile (3a, 3c) of the metal structure (3) and at a certain distance from one of the said closing profiles (3a).

[0198] Preferably, the chamber (11) of the box beam (10) is gastight. Preferably, the dry gas contained within the chamber (11) of the box beam (10) is (i) an inert gas selected from one of the following: nitrogen, argon, krypton or xenon or a mixture of any of them; or

[0199] (11) carbon dioxide.

[0200] Figure 7 shows a schematic view of the main elements and their various connections of an example of an embodiment of the system comprising, in addition to the box beam (10), means for compensating pressure variations inside the box beam (10) with respect to the outside atmospheric pressure, according to a second inventive aspect of the invention.

[0201] In said Figure 7, the direction of gas flow along the closed-loop circuit is represented by arrows. The gas outlet ("out") of the chamber (11) of the box beam (10) is connected via a first non-return valve (15) to a second reservoir (18), which is at a pressure close to atmospheric pressure, followed by a compressor (14) and the latter is connected via a second solenoid valve (17), preferably a three-way solenoid valve, to the pressurised reservoir (12). A non-return valve (16) is also provided between the second solenoid valve (17) and the pressurised reservoir (12) to preserve the integrity of the compressor motor (14) in case of failure of the second solenoid valve (17). The entire fluidic connection from the gas outlet point ("out") of the chamber (11) to the pressurised reservoir (12) corresponds to the second fluidic connection (CF2), where the second fluidic connection (CF2) between the chamber (11) and the pressurised reservoir (12) is configured to allow the gas to exit from the chamber (11) towards the pressurised reservoir (12), with the interposition of the various elements mentioned above.

[0202] A first solenoid valve (13) is connected to the outlet of the pressurised reservoir (12) and optionally a throttle section (23) is provided, which restricts at least the flow rate that finally enters the chamber (11) through the inlet connection ("in"). The entire fluidic connection from the outlet of the pressurised reservoir (12) to the inlet ("in") to the chamber (11) of the box beam (10) corresponds to the first fluidic connection (CF1), where the first fluidic connection (CF1) between the pressurised reservoir (12) and the chamber (11) is configured to allow gas to enter from the pressurised reservoir (12) to the chamber (11), with the interposition of the various elements mentioned above.

[0203] Preferably, the pressurised reservoir (12) and the second reservoir (18) are gas conducting elements (pipes) with a sufficient diameter to store the gas required by the application.

[0204] Preferably, an additional fluidic connection (CF3) bridges the outlet and inlet of the compressor (14) from the second solenoid valve (17) to the first reservoir (18) with pressure close to atmospheric pressure.

[0205] The system includes at least one relative pressure sensor (19) connected to the chamber (11) of the box beam (10) that measures the pressure difference between the gas in the chamber (11) and the air in the outside atmosphere. In the embodiment of the system shown in Figure 7, there is a single relative pressure sensor (19). The control means of the system are not shown in this Figure 7.

[0206] The control means are in communication with the relative pressure sensor (19) and are adapted to, depending on the pressure differential value between the chamber (11) and the atmospheric pressure received from the relative pressure sensor (19), command the opening of the first solenoid valve (13), the actuation of the compressor (14), or the opening of the second solenoid valve (17).

[0207] The relative pressure sensor (19) operates, in this case, in such a way that when it detects an overpressure higher than a preset limit value (for example 1 mbar), the control means activate the compressor (14) and open the second solenoid valve (17) which opens the gas passage to the pressurised reservoir (12) while closing the passage to the second reservoir (18) and the control means close the first solenoid valve (13). In this way, the compressor (14) sucks gas from the chamber (11) of the box beam (10) and it is stored under pressure in the pressurised reservoir (12). If the relative pressure sensor (19) detects an underpressure above the set limit value (for example -1 mbar), the compressor (14) is at rest, the solenoid valve (13) opens and the pressurised reservoir (12) releases gas into the chamber (11) of the box beam (10) through the throttle section (23).

[0208] Optionally, when the compressor (14) is at rest, the second solenoid valve (17) keeps the passage closed towards the pressurised reservoir (12) and opens it towards the second reservoir (18) at least temporarily for the time necessary to dissipate the pressures inside the second reservoir (18). In this way, the high pressures stored in the section between the compressor (14) and the second solenoid valve (17) are dissipated inside the second reservoir (18). In this way, it is possible to maintain relaxed pressures (close to atmospheric pressure) in the vicinity of the compressor (14), both at its inlet and outlet, which allows the compressor (14) to start easily without resistance when required.

[0209] Figures 8 and 9 show respective schematic views of the various elements that configure two different embodiments of the means for mitigating the heat transfer through the chamber of the box beam, according to a second inventive aspect of the invention.

[0210] In the embodiment shown in figure 8, the system further comprises: a first temperature sensor (TS1) located in the pressurized reservoir (12), and a second temperature sensor (TS2) located in the chamber (11) of the box beam (10); wherein the control means are further in communication with the first and second temperature sensors (TS1, TS2), and further adapted to act according to a heat exchanging mode of operation between the chamber (11) and the pressurized reservoir (12) comprising: either activating the introduction of gas into the chamber (11) by transferring gas from the pressurized reservoir (12) into the chamber (11), or activating the extraction of gas from the chamber (11) by transferring gas from the chamber (11) to the pressurized reservoir (12), or simultaneously activating both of the above; and wherein the control means is further adapted to activate the heat exchanging mode of operation between the chamber (11) and the pressurized reservoir (12) when: i) the absolute value of the temperature difference between the measurement of the first temperature sensor (TS1) and the measurement of the second temperature sensor (TS2) exceeds a predetermined threshold value; or ii) the difference between the measurement of the second temperature sensor (TS2) and a first reference value is higher than a predetermined threshold value, when the measurement of the second temperature sensor (TS2) is higher than said first reference value; or iii) the difference between a second reference value and the measurement of the second temperature sensor (TS2) is higher than a predetermined threshold value, when the measurement of the second temperature sensor (TS2) is lowerthan said second reference value.

[0211] The previous term "activating the introduction of gas into the chamber (11) by transferring gas from the pressurized reservoir (12) into the chamber (11)", refers to the process of at least opening the first solenoid valve (13) of the first fluidic connection (CF1); and the previous term "activating the extraction of gas from the chamber (11) by transferring gas from the chamber (11) to the pressurized reservoir (12)", refers to the process of at least activating the compressor (14) of the second fluidic connection (CF2).

[0212] Although the gas inlet ("in") and gas outlet ("out") points are represented in figures 7, 8 and 9 on the same side of the box beam (10), in other embodiments (not shown) the gas inlet point ("in") and the gas outlet point ("out") of the chamber (11) are positioned at a different height. For instance, the gas inlet point ("in") could be in the position depicted, while the gas outlet point (out) could be on the opposite side of the box beam

[0213] (10).

[0214] In the embodiment shown in figure 9, the system comprises, in addition to the first and second temperature sensors (TS1, TS2), a third temperature sensor (TS3) located in the chamber (11); and wherein one sensor, selected from the second temperature sensor (TS2) or the third temperature sensor (TS3), is located in a lower part of the chamber

[0215] (11) according to the direction of gravity action when the chamber (11) is in an operating position, and the other temperature sensor, selected from the second temperature sensor (TS2) or the third temperature sensor (TS3), is located in a higher part of the chamber (11), above the previous one sensor; and optionally wherein the control means -M - are further adapted to activate the heat exchanging mode of operation when the absolute value of the difference of temperature measurements obtained at the second temperature sensor (TS2) and the third temperature sensor (TS3) are above a predetermined threshold value.

[0216] Regarding the location of the second and third temperature sensors (TS2, TS3) of the chamber (11) in the embodiment shown in figure 9, one of both temperature sensors, in this particular case the third temperature sensor (TS3), is located in a lower part of the chamber (11) according to the direction of gravity action when the chamber (11) is in an operating position; while the other temperature sensor, in this particular case the second temperature sensor (TS2), is located in a higher part of the chamber (11), above the third temperature sensor (TS3). This configuration of the second and third temperature sensors (TS2, TS3) being arranged at distinct positions or heights within the chamber (11) of the box beam (10) allows for the measurement of the temperature differential between the top and bottom parts of the chamber (11) as the gas stratifies within the chamber (11), which implies a temperature gradient.

[0217] Furthermore, the present invention describes a method of manufacturing the box beam (10) according to a third aspect of the invention. In the following, a specific example of a method of manufacturing the box beam (10) is described in relation to the figures described above. The method makes use of the following elements: a support (not shown in the figures); a first glass plate (1), having an outer surface (1.1) and an inner surface (1.2) arranged opposite to the outer surface (1.1), said first glass plate (1) consisting of a laminate as shown in Figures 3 and 4; a second glass plate (2), having an outer surface (2.1) and an inner surface (2.2) arranged opposite to the outer surface (2.1), said second glass plate (2) consisting of a laminate such as the one shown in Figure 3; wherein the first and second glass plates (1, 2) have the same dimensions in width and length; two metal longitudinal profiles (3b, 3d), extending along a given rectilinear longitudinal path, comprising a first lateral surface (3.1) with a first seat (3.1.1) adapted to receive a perimeter part of the inner surface (1.2) of the first glass plate (1) and a second lateral surface (3.2) of reception, arranged opposite to the first lateral surface (3.1), with a second seat (3.2.1) adapted to receive a perimeter part of the inner surface (2.2) of the second glass plate (2); two metal closing profiles (3a, 3c), extending along a given transverse and rectilinear path, comprising a first lateral surface (3.1) with a first seat (3.1.1) adapted to receive a perimeter part of the inner surface (1.2) of the first glass plate (1), and a second lateral surface (3.2), arranged opposite to the first lateral surface (3.1), with a second seat (3.2.1) adapted to receive a perimeter part of the inner surface (2.2) of the second glass plate (2); wherein the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c) form a rectangular closed perimeter path, wherein each longitudinal profile (3b, 3d) and each closing profile (3a, 3c) forms a side of the rectangle; and wherein the cross-section of the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c) is rectangular and solid (see Figure 3); wherein the method of manufacturing the box beam (10) comprises the steps of: rest the outer surface (1.1) of the first glass plate (1) on the support;

[0218] - join the two longitudinal profiles (3b, 3d) with the two closing profiles (3a, 3c) to form a closed metal structure (3) as shown in Figure 5, bond the metal frame (3) to the first glass plate (1) by means of a first joint (4a) (as shown in Figure 3) formed by arranging a first adhesive bead, the first adhesive bead extending along a closed path, provide a second joint (4b) (as shown in Figure 3) formed by arranging a second adhesive bead on at least a portion of the second lateral surface (3.2) of the metal structure (3) with the second adhesive bead extending along a closed path, bring the inner surface (2.2) of the second glass plate (2) into contact with the second lateral surface (3.2) of the metal structure (3) provided with the second adhesive bead, to bond the metal structure (3) to the second glass plate (2), so as to obtain the assembled box beam (10), filling of the chamber (11) of the box beam (10) with a dry gas.

[0219] Attached Figures 1-4 show the box beam (10) already assembled.

[0220] In an embodiment (not shown in the attached figures), the step of bonding the metal structure (3) to the first glass plate (1) by means of a first joint formed by means of a first adhesive bead is according to an option a) or an option b), where option a) comprises the sub-stages of: al) provide a first adhesive bead on at least a portion near to or touching the perimeter edge of the inner surface (1.2) of the first glass plate (1), and a2) bring the first lateral surface (3.1) of the metal structure (3) into contact with the inner surface (1.2) of the first glass plate (1) provided with the first adhesive bead, in order to bond the metal structure (3) to the first glass plate (1), where option b) comprises the sub-stages of: bl) rest the second lateral surface (3.2) of the metal structure (3) on the inner surface (1.2) of the first glass plate (1) which is on the support, b2) provide a first adhesive bead on at least a portion of the first lateral surface (3.1) of the metal structure (3), and b3) position the metal structure (3) with the first adhesive bead facing the inner surface (1.2) of the first glass plate (1) and bring the first lateral surface (3.1) of the metal structure (3) provided with the first adhesive bead into contact with the inner surface (1.2) of the first glass plate (1), in order to bond the metal structure (3) to the first glass plate (1).

[0221] In an embodiment, the dry gas in the chamber filling stage (11) is selected from (i) an inert gas, preferably selected from one of the following: nitrogen, argon, krypton, xenon or a mixture of any of them; or (ii) carbon dioxide.

[0222] In an embodiment (not shown in the accompanying figures), prior to the step of filling the chamber (11) of the box beam (10) with a dry gas, the method further comprises the step of purging the moist air from the chamber (11) of the box beam (10).

[0223] In an embodiment (not shown in the accompanying figures), after the step of contacting the inner surface (2.2) of the second glass plate (2) with the second lateral surface (3.2) of the metal structure (3) provided with the second adhesive bead for bonding the metal structure (3) to the second glass plate (2), the method further comprises the steps of: heat curing the first and second adhesive bead of the box beam (10), and cooling the assembled and cured box beam (10).

[0224] In a more specific embodiment (not shown in the attached figures), the heat curing step of the first and second adhesive bead of the box beam (10) is performed by placing the assembled box beam (10) inside an oven, preferably by resting the box beam (10) on a support and in a horizontal position, and preferably at a temperature between 80 and 120 °C for a time between 0.5 and 4 hours. In an embodiment, the curing temperature inside the oven is achieved by a gentle ramp up of temperature, which minimises mechanical stresses of thermal origin in the box beam. In a more specific embodiment, the cooling stage of the assembled and cured box beam (10) consists of a slow cooling of the assembled and cured box beam (10) by letting hot air escape from inside the oven.

[0225] In an embodiment (not shown in the attached figures), prior to the steps of joining the metal structure (3) to the first glass plate (1) by means of a first joint (4a) and providing a second joint (4b), the method further comprises the step of applying a primer layer (not shown in the attached figures) on the surfaces of the metal structure (3) and on the surfaces of the first and second glass plates (1,2), that will be bonded by the first and second adhesive bead, wherein the purpose of the primer layer is to act as a corrosion protector and / or adhesion promoter.

[0226] In an embodiment (not shown in the attached figures), prior to the steps of bonding the metal structure (3) to the first glass plate (1) by means of a first joint (4a) and providing a second joint (4b), the method further comprises the step of arranging a plurality of spacers (7) between the metal structure (3) and each glass plate (1, 2), and wherein the spacers (7) are inserted in different positions within the perimeter channels (8a). The plurality of spacers (7) are preferably configured as blocks, see Figure 4 where one of them is shown in a dashed line, preferably made of a cured adhesive, and more preferably of the same adhesive as the first and second adhesive bead.

[0227] In an embodiment, the step of joining the two longitudinal profiles (3b, 3d) with the two closing profiles (3a, 3c) forming a closed metal structure (3) is by welding (not shown in the attached figures).

Claims

CLAIMS1.- Box beam (10), comprising: a first glass plate (1), having an outer surface (1.1) and an inner surface (1.2) arranged opposite to the outer surface (1.1); a second glass plate (2), having an outer surface (2.1) and an inner surface (2.2) arranged opposite to the outer surface (2.1), wherein the second glass plate (2) is arranged parallel to the first glass plate (1) and spaced apart from the first glass plate (1); two metal longitudinal profiles (3b, 3d), essentially parallel and spaced apart, extending along a certain longitudinal path, the two longitudinal profiles (3b, 3d) being interposed between the inner surface (1.2) of the first glass plate (1) and the inner surface (2.2) of the second glass plate (2), wherein the two longitudinal profiles (3b, 3d) comprise: a first lateral receiving surface (3.1) with a first seat (3.1.1) adapted to receive a perimeter part of the inner surface (1.2) of the first glass plate (1), and a second lateral receiving surface (3.2), arranged opposite to the first lateral surface (3.1), with a second seat (3.2.1) adapted to receive a perimeter part of the inner surface (2.2) of the second glass plate (2); two metal closing profiles (3a, 3c), configured such that the ends of the longitudinal profiles (3b, 3d) are joined by the two closing profiles (3a, 3c) at one end and the other end, forming a closed metal structure (3), the two closing profiles (3a, 3c) being interposed between the inner surface (1.2) of the first glass plate (1) and the inner surface (2.2) of the second glass plate (2), and wherein the two closing profiles (3a, 3c) comprise: a first lateral receiving surface (3.1) with a first seat (3.1.1) adapted to receive a perimeter part of the inner surface (1.2) of the first glass plate (1), and a second lateral receiving surface (3.2), arranged opposite to the first lateral surface (3.1), with a second seat (3.2.1) adapted to receive a perimeter part of the inner surface (2.2) of the second glass plate (2); and where the first glass plate (1) is connected to the first seat (3.1.1) of the first lateral surface (3.1) of the two longitudinal profiles (3b, 3d) and of the two closing profiles (3a, 3c) by means of a first structural and gastight joint (4a); and the second glass plate (2) is connected to the second seat (3.2.1) of the second lateral surface (3.2) of the two longitudinal profiles (3b, 3d) and of the two closingprofiles (3a, 3c) by means of a second structural and gastight joint (4b); and wherein the inner space bounded by the inner surface (1.2) of the first glass plate (1), the inner surface (2.2) of the second glass plate (2) and an inner surface (3.3) of the closed metal structure (3) formed by the metal longitudinal profiles (3b, 3d) and the metal closing profiles (3a, 3c) forms a chamber (11), wherein the chamber (11) comprises a gas.2.- Box beam (10) according to claim 1, further comprising an opaque coating (9a, 9b) arranged on the first glass plate (1), on the second glass plate (2), or on both (1, 2), and extending in a region at least occupying the interior bounded by the projection of the two longitudinal profiles (3b, 3d) and the two closing profiles (3a, 3c) on the glass plate (1, 2), wherein the projection is in the direction perpendicular to said glass plate (1, 2).3.- Box beam (10) according to any one of the preceding claims, wherein the first joint (4a) and the second joint (4b) extend along a closed path.4.- Box beam (10) according to any one of the preceding claims, wherein the first joint (4a) and the second joint (4b) are a high-strength structural adhesive, preferably a thermally cured epoxy-based adhesive.5.- Box beam (10) according to the previous claim, wherein the high-strength structural adhesive of the first joint (4a) and the second joi nt(4b) has a layer thickness in a range between 0.2mm to 4mm, more preferably in a range between 0.2mm to 2,5mm, more preferably in a range between 0.5mm to 2mm, more preferably in a range between 1mm and 2mm, more preferably in a range between 0.8 and 1.2, and more preferably about 1mm.6.- Box beam (10) according to any one of the preceding claims, wherein the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c) form a rectangular closed perimeter path, wherein each longitudinal profile (3b, 3d) and each closing profile (3a, 3c) configures one side of the rectangle.7.- Box beam (10) according to the previous claim, where the first and second glass plates (1, 2) have the same width and length dimensions.8.- Box beam (10) according to any one of the preceding claims, wherein the longitudinalprofiles (3b, 3d) and the closing profiles (3a, 3c) are configured according to a substantially polygonal cross-section, preferably a rectangular cross-section, and wherein the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c) are preferably solid.9.- Box beam (10) according to any one of the preceding claims, wherein the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c) are made of stainless steel or titanium or any other metallic material with a coefficient of thermal expansion between 8.5-10’6and 11.5-10-6(°C -1).10.- Box beam (10) according to any one of the preceding claims, wherein at least a part of the first lateral surface (3.1) of the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c), and / or at least a part of the second lateral surface (3.2) of the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c), and / or at least a part of a surface of the first glass plate (1) and / or at least a part of a surface of the second glass plate (2) is curved.11.- Box beam (10) according to any one of the preceding claims, wherein each of the longitudinal profiles (3b, 3d) and the closing profiles (3a, 3c) comprises a continuous perimeter channel (8a, 8b) located on the first lateral receiving surface (3.1), on the second lateral receiving surface (3.2) or on both lateral receiving surfaces (3.1, 3.2), and the perimeter channels (8a, 8b) being spaced apart from the inner surfaces (3.3) of the longitudinal profiles (3b, 3d) and of the closing profiles (3a, 3c) in contact with the chamber (11), the perimeter channels (8a, 8b) being configured as receptacles for receiving the excess adhesive from the joint (4a, 4b) and preventing it from overflowing and entering the chamber (11).12.- Box beam (10) according to any one of the preceding claims, further comprising at least one crossmember (24) arranged between two profiles (3b, 3d, 3a, 3c) of the metal structure (3), wherein the at least one crossmember (24) is configured for reinforcement against impacts such as the impact of a vehicle, and wherein preferably: the first glass plate (1) is further connected to a first surface of the at least one crossmember (24) by means of a first structural and gastight joint (4a); and the second glass plate (2) is further connected to a second surface of the at least one crossmember (24) by means of a second structural and gastight joint (4b).13.- Box beam (10) according to any one of the preceding claims, further comprising one or more support seats, wherein the one or more support seats are in a part of the first glass plate (1) and / or in a part of the second glass plate (2), such that the support seats are adapted to provide stability to the box beam against external actions when the box beam is supported in a working position on a surface.14.- Box beam (10) according to any one of the previous claims, wherein the chamber (11) is gastight.15.- Box beam (10) according to any one of the preceding claims, wherein the gas contained within the chamber (11) is selected from: an inert gas, preferably selected from one of the following: nitrogen, argon, krypton, xenon or a mixture of any of these; or carbon dioxide.16.- System, comprising the box beam (10) according to any one of the preceding claims, and further, means for compensating the pressure variations of the gas contained within the chamber (11) of the box beam (10), wherein the means for compensating the gas pressure within the chamber (11) comprise the following elements connected, in an operational mode, in a closed-loop circuit with the interior of the chamber (11): a pressurised reservoir (12), which in operational mode comprises a gas at a pressure above atmospheric pressure, wherein the box beam (10) is connected to the pressurised reservoir (12) by means of a first fluidic connection (CF1) and a second fluidic connection (CF2), wherein: the first fluidic connection (CF1) between the pressurised reservoir (12) and the chamber (11) is configured to allow gas from the pressurised reservoir (12) to enter the chamber (11), with the interposition of a first solenoid valve (13) to regulate the introduction of gas from the pressurised reservoir (12) into the chamber (11), and the second fluidic connection (CF2) between the pressurised reservoir (12) and the chamber (11) is configured to allow gas to flow out of the chamber (11) into the pressurised reservoir (12), with the interposition of a compressor (14); at least one relative pressure sensor (19) configured to measure the pressureimbalance between the pressure inside the chamber (11) of the box beam (10) and atmospheric pressure; control means in communication with the relative pressure sensor (19) adapted to, depending on the pressure differential value between the chamber (11) and the atmospheric pressure received from the relative pressure sensor (19), command: the opening of the first solenoid valve (13) of the first fluidic connection (CF1), in case the differential value between the pressure inside the chamber (11) of the box beam (10) and the atmospheric pressure is lower than a predetermined threshold value, or the activation of the compressor (14) of the second fluidic connection (CF2), in case the difference between the pressure inside the chamber (11) of the box beam (10) and the atmospheric pressure is greater than a predetermined threshold value.17.- System according to the previous claim, further comprising a first non-return valve(15) in the second fluidic connection (CF2), located between the compressor (14) and the chamber (11), wherein said first non-return valve (15) is oriented to allow the gas to exit the chamber (11).18.- System according to claim 16 or 17, further comprising a second non-return valve(16) in the second fluidic connection (CF2), located between the compressor (14) and the pressurised reservoir (12), wherein said second non-return valve (16) is oriented to allow the passage of gas from the compressor (14) to the pressurised reservoir (12).19.- System according to any one of claims 16 to 18, wherein the means for compensating the gas pressure inside the chamber (11) further comprises in the second fluidic connection (CF2): a second three-way solenoid valve (17) between the compressor (14) and the pressurised reservoir (12), and a second reservoir (18) arranged between the compressor (14) and the first nonreturn valve (15), wherein the second solenoid valve (17) is further connected to the second reservoir (18) via a third fluidic connection (CF3), wherein the third fluidic connection (CF3) is configured to allow gas to exit from the second fluidic connection (CF2) where the second solenoid valve (17) is located into the second reservoir (18); andwherein the control means are further adapted to, after the compressor (14) has stopped, command: the opening of the second solenoid valve (17) of the second fluidic connection (CF2), to open the gas passage to the third fluidic connection (CF3) towards the second reservoir (18), equalising the pressure at the inlet and outlet of the compressor (14).20.- System according to any one of claims 16 to 19, wherein the means for compensating the gas pressure inside the chamber (11) further comprise a throttle section (23) at the first fluidic connection (CF1) for reducing at least the gas inlet flow rate into the chamber (11) from the pressurized reservoir (12), where preferably the throttle section (23) is interposed between the first solenoid valve (13) and the gas inlet point ("in") to the chamber (11) of the box beam (10).21.- System according to any one of claims 16 to 20, wherein the gas inlet point ("in") and the gas outlet point ("out") of the chamber (11) are positioned at a different height.22.- System according to any one of claims 16 to 21, further comprising: a first temperature sensor (TS1) located in the pressurized reservoir (12), and a second temperature sensor (TS2) located in the chamber (11) of the box beam (10); wherein the control means are further in communication with the first and second temperature sensors (TS1, TS2), and further adapted to act according to a heat exchanging mode of operation between the chamber (11) and the pressurized reservoir (12) comprising: either activating the introduction of gas into the chamber (11) by transferring gas from the pressurized reservoir (12) into the chamber (11), or activating the extraction of gas from the chamber (11) by transferring gas from the chamber (11) to the pressurized reservoir (12), or simultaneously activating both of the above; and wherein the control means is further adapted to activate the heat exchanging mode of operation between the chamber (11) and the pressurized reservoir (12) when: i) the absolute value of the temperature difference between the measurement of the first temperature sensor (TS1) and the measurement of the second temperature sensor (TS2) exceeds a predetermined threshold value; orii) the difference between the measurement of the second temperature sensor (TS2) and a first reference value is higher than a predetermined threshold value, when the measurement of the second temperature sensor (TS2) is higher than said first reference value; or iii) the difference between a second reference value and the measurement of the second temperature sensor (TS2) is higher than a predetermined threshold value, when the measurement of the second temperature sensor (TS2) is lowerthan said second reference value.23.- System according to the previous claim, wherein: activating the introduction of gas into the chamber (11) by transferring gas from the pressurized reservoir (12) into the chamber (11) is at least opening the first solenoid valve (13) of the first fluidic connection (CF1); and activating the extraction of gas from the chamber (11) by transferring gas from the chamber (11) to the pressurized reservoir (12) is at least activating the compressor (14) of the second fluidic connection (CF2).24.- System according to any one of claims 22 or 23, wherein the reference value is a measurement of the temperature of a zone protected by the box beam (10).25.- System according to any one of claims 22 to 24, wherein:- the activation of the gas introduction into the chamber (11) in the heat exchanging operation mode is automatically activated when the pressure difference between the inside and the outside of the chamber (11) drops below a predetermined pressure threshold value; and / or- the activation of gas extraction in the chamber (11) in the heat exchanging operation mode is automatically activated when the pressure difference between the inside and the outside of the chamber (11) rises above a predetermined pressure threshold value.26.- System according to any one of claims 22 to 25, further comprising a third temperature sensor (TS3) located in the chamber (11); and wherein one sensor, selected from the second temperature sensor (TS2) or the third temperature sensor (TS3), is located in a lower part of the chamber (11) according to the direction of gravity action when the chamber (11) is in an operating position, and the other temperature sensor, selected from the second temperature sensor (TS2) or the third temperature sensor(TS3), is located in a higher part of the chamber (11), above the previous one sensor; and optionally wherein the control means are further adapted to activate the heat exchanging mode of operation when the absolute value of the difference of temperature measurements obtained at the second temperature sensor (TS2) and the third temperature sensor (TS3) are above a predetermined threshold value.27.- Method of manufacturing the box beam (10) according to any one of claims 1 to 15, which makes use of the following elements: a support; a first glass plate (1), having an outer surface (1.1) and an inner surface (1.2) arranged opposite to the outer surface (1.1); a second glass plate (2), having an outer surface (2.1) and an inner surface (2.2) arranged opposite to the outer surface (2.1); two metal longitudinal profiles (3b, 3d), extending along a given longitudinal path, comprising a first lateral receiving surface (3.1) with a first seat (3.1.1) adapted to receive a perimeter part of the inner surface (1.2) of the first glass plate (1) and a second lateral receiving surface (3.2), arranged opposite to the first lateral surface (3.1), with a second seat (3.2.1) adapted to receive a perimeter part of the inner surface (2.2) of the second glass plate (2); two metal closing profiles (3a, 3c), comprising a first lateral receiving surface (3.1) with a first seat (3.1.1) adapted to receive a perimeter part of the inner surface (1.2) of the first glass plate (1), and a second lateral receiving surface (3.2), arranged opposite to the first lateral surface (3.1), with a second seat (3.2.1) adapted to receive a perimeter part of the inner surface (2.2) of the second glass plate (2); wherein the method of manufacturing the box beam (10) comprises the steps of: rest the outer surface (1.1) of the first glass plate (1) on the support; connect the two longitudinal profiles (3b, 3d) with the two closing profiles (3a, 3c) to form a closed metal structure (3), bond the metal structure (3) to the first glass plate (1) by means of a first joint (4a) formed by the provision of a first adhesive bead, provide fora second joint (4b) formed by the provision of a second adhesive bead on at least a portion of the second lateral surface (3.2) of the metal structure (3), bring the inner surface (2.2) of the second glass plate (2) into contact with the second lateral surface (3.2) of the metal structure (3) provided with the second adhesive bead, to bond the metal structure (3) to the second glass plate (2), so as to obtain the assembled box beam (10),filling of the chamber (11) of the box beam (10) with a dry gas.28.- The method of manufacturing the box beam (10) according to the preceding claim, wherein the step of bonding the metal structure (3) to the first glass plate (1) by means of a first joint (4a) formed by means of a first adhesive bead is according to an option a) or an option b), where option a) comprises the sub-stages of: al) provide a first adhesive bead on at least a portion near or touching the perimeter edge of the inner surface (1.2) of the first glass plate (1), and a 2) bring the first lateral surface (3.1) of the metal structure (3) into contact with the inner surface (1.2) of the first glass plate (1) provided with the first adhesive bead, in order to bond the metal structure (3) to the first glass plate (1), where option b) comprises the sub-stages of: bl) rest the second lateral surface (3.2) of the metal structure (3) on the inner surface (1.2) of the first glass plate (1) which is on the support, b2) provide a first adhesive bead on at least a portion of the first lateral surface (3.1) of the metal structure (3), and b3) position the metal structure (3) with the first adhesive bead facing the inner surface (1.2) of the first glass plate (1) and bring the first lateral surface (3.1) of the metal structure (3) with the first adhesive bead into contact with the inner surface (1.2) of the first glass plate (1), in order to bond the metal structure (3) to the first glass plate (1).29.- The method of manufacturing the box beam (10) according to claim 27 or 28, wherein the dry gas in the chamber filling stage (11) is selected from: an inert gas, preferably selected from one of the following: nitrogen, argon, krypton, xenon or a mixture of any of these; or carbon dioxide.30.- The method of manufacturing the box beam (10) according to any one of claims 27 to 29, wherein, after the step of contacting the inner surface (2.2) of the second glass plate (2) with the second lateral surface (3.2) of the metal structure (3) provided with the second adhesive bead for bonding the metal structure (3) to the second glass plate (2), further comprises the steps of: heat curing of the first and second adhesive bead of the box beam (10), preferably by placing the assembled box beam (10) inside an oven, preferablywith the box beam (10) resting on a support and in a horizontal position, and preferably at a temperature between 80 and 120 °C for a time between 0.5 and 4 hours; and cooling of the assembled and cured box beam (10), preferably consisting of a slow cooling of the assembled and cured box beam (10) by allowing hot air to escape from inside the oven.31.- The method of manufacturing the box beam (10) according to any one of claims 27 to 30, wherein, before the steps of bonding the metal structure (3) to the first glass plate (1) by means of a first joint (4a) and providing a second joint (4b), it further comprises the step of: apply a primer layer as a corrosion protection and / or adhesion promoter on the surfaces of the metal structure (3) and on the surfaces of the first and second glass plates (1,2) which will be bonded by the first and second adhesive bead.32.- The method of manufacturing the box beam (10) according to any one of claims 27 to 31, wherein, prior to the steps of bonding the metal frame (3) to the first glass plate (1) by means of a first joint (4a) and arranging a second joint (4b), further comprises the step of arranging a plurality of spacers (7), preferably inserted in different positions in the perimeter channels (8a, 8b), between the metal structure (3) and each glass plate (1, 2), wherein the plurality of spacers (7) are preferably configured as blocks, preferably made of a cured adhesive, and more preferably of the same adhesive as the first and second adhesive bead.

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