WO2003058112A1

WO2003058112A1 - Constructional element for the creation of a conveyor system for aeriform media

Info

Publication number: WO2003058112A1
Application number: PCT/IT2002/000006
Authority: WO
Inventors: Giuseppe Librizzi
Original assignee: Al.P.S.R.L.
Priority date: 2002-01-10
Filing date: 2002-01-10
Publication date: 2003-07-17
Also published as: AU2002232121A1; DE10297625T5; ES1053723U; ES1053723Y; HUP0500789A2

Abstract

A prefabricated contructional element 81) for the creation of a conveyor system (20) for aeriform media, in particular for conditioned air (19), comprises a rigid, plate-shaped element (2) resistant to local deformation with a smooth surface (5) which is impermeable to gases, for delimiting a conveyor space (15). The constructional element (1) also comprising a pliable, plate-shaped and thermally insulating element (3) which is less stiff than the rigid element (2) and is connected uniformly to the rigid element (2) along the surface remote from the at least one smooth surface (5), achieving a yielding relative restraint over the whole extent of the rigid element (2).

Description

DESCRIPTION "Constructional element for the creation of a conveyor system for aeriform media"

The subject of the present invention is a constructional element for the creation of a conveyor system for aeriform media, in particular for air in air- conditioning and climate-control systems.

Conveyor systems for conditioned air have to satisfy a large number of sometimes conflicting requirements arising mainly from the difference between the physical/climatic environments inside and outside the conveyor system.

One of the main tasks of an air-conveyor system is that of keeping the temperature, humidity and cleanliness of the air conveyed within a predetermined range, preventing both excessive use of energy and mutual contamination of the environments outside and inside the conveyor system.

There are known conveyor systems for aeriform media, in particular for conditioned air, in which a duct is formed by continuous or welded metal piping or by metal or plastics box sections assembled by means of reinforcing and connection elements to form a branched system which is able both to supply "fresh" air and to withdraw "stale" air in the areas of a building or of an industrial plant in which conditioning is required.

To achieve effective thermal separation of the air conveyed from the outside environment, the piping has to be wrapped in thermally insulating material, for example, fibreglass, rock wool, or polystyrene. In order to hold the thermally-insulating material closely around the pipes or the box sections, the conveyor system is covered externally with a protective casing, typically of synthetic material or metal. However, the systems of the prior art have some functional and structural problems and disadvantages.

Owing to difficulties with regard to space and accessibility in many areas of a building, uniform application of the thermally insulating material and of the outer protective casing of the tubing is impossible. In fact there are always critical regions, for example, openings in walls, through which the pipes extend without any thermal protection.

The large volume of air transported by means of these conveyor systems requires the individual ducts to have very large cross-sections, rendering the use of box sections difficult. In fact, in box sections composed of panels of substantially synthetic material, as the size of the panels increases, their pliability is such as to necessitate reinforcing profiles, for example, at the corners, making assembly expensive and difficult.

Metal box sections have the disadvantage of noisiness due to vibrations and because of "knocking" due to warping, for example, as a result of thermal deformation.

In some areas such as, for example, in hospitals, in the food industry, and in the semiconductor industry, a very clean working environment is required. Frequent inspections and washing of the air-conveyor ducts consequently necessitate periodic dismantling and subsequent refitting of various parts of the conveyor system. Up to now, these operations have been very difficult and therefore expensive, as well as also leading to wear and damage of the thermally-insulating material which in turn creates polluting dust which is released each time the system is dismantled.

The conveyor systems of the prior art have the further disadvantage of producing an undesired acoustic connection between different areas of a building, transmitting voices and machinery noises, for example, the noise of the fans of the conveyor system.

In the operating condition, the air-flow also produces vibrations in the walls of the piping, causing a noise which is well known to be annoying. Moreover, the fact that it is not possible to adapt all thermally-insulating materials easily to the external shape of the conveyor duct leads to difficulties during assembly and to a high percentage of waste and also limits the number of thermally-insulating materials available.

The object of the present invention is therefore to provide a constructional element for the creation of a conveyor system for aeriform media, in particular conditioned air, having characteristics such as to overcome the problems mentioned with reference to the prior art .

This and other objects are achieved by means of a constructional element according to Claim 1, as well as by means of a conveyor duct according to Claim 15 and a conveyor system according to Claim 23.

For a better understanding of the invention, an embodiment thereof will be described below, by way of non-limiting example, with reference to the appended drawings, in which: Figure 1 is a perspective view of a constructional element according to the invention,

Figure 2 is an enlarged schematic representation of the detail II of Figure 1,

Figures 3a, 3b and 3c show three embodiments of the constructional element according to the invention, Figures 4a, 4b and 4c show the main steps of the method of producing a portion of conveyor duct according to the invention, by means of the constructional element according to the invention, Figures 5a, 5b show the main steps of the method for producing a further portion of conveyor duct according to the invention, by means of a further constructional element according to the invention,

Figures 6a to 6f show cross-sections of duct portions produced by means of the constructional element according to the invention,

Figure 7 is a partially-exploded, perspective view of a forked duct portion, produced by means of the constructional element according to the invention, Figure 8 shows the acoustic behaviour of a constructional element according to the invention, and

Figure 9 is a schematic view of the production of a constructional element according to the invention.

With reference to Figure 1, a constructional element for the creation of a conveyor system for aeriform media is generally indicated 1. The constructional element 1 is advantageously prefabricated and comprises a rigid element 2 and a pliable element 3. Both the rigid element 2 and the pliable element 3 are substantially plate-shaped and the thickness of the rigid element 2 is less than the thickness of the pliable element 3. The rigid element is resistant to local deformation and to corrosion and has at least one surface 5 which is smooth, substantially flat, and impermeable to gases. The pliable element 3 is made of resilient or viscoelastic material and has a low thermal transmittance value.

The pliable element 3 is less stiff than the rigid element 2 and is connected uniformly thereto along the surface remote from smooth surface 5, forming a yielding relative restraint over the whole extent of the rigid element 2.

The rigid element 2 and the pliable element 3 advantageously have substantially uniform thicknesses, forming a constructional element 1 of substantially uniform thickness.

According to one embodiment, the constructional element 1 also comprises a protective sheet 4 of material which is preferably non-inflammable and resistant to water and to ultraviolet light. The protective sheet 4 is associated with the exposed surface of the pliable element 3 remote from the surface that is connected to the rigid element 2.

The rigid element 2 and the pliable element 3 are advantageously connected to form a substantially flat and self-supporting "sandwich"-type structure. To create specific shapes of the constructional element, the "sandwich" structure may be subjected to mechanical or thermal treatment in which the rigid element 2 and the pliable element 3 are shaped together. This also enables a controlled state of residual tensions to be introduced into the constructional element 1, enabling the above- mentioned yielding relative restraint of the rigid element 2 to be varied within certain limits. Figure 3 shows three embodiments of the uniform connection between the pliable element 3 and the rigid element 2. In Figure 3a, the connection is formed by a connection area 6, for example, a gluing area, extending uninterruptedly over the entire surface. In Figures 3b and 3c, the connection is discontinuous with connection areas 6 which extend, for example, along parallel lines and which have spacings that are small in comparison with the buckling length of the rigid element in the vibration modes which are usually excited by an air-flow along the smooth surface 5. This ensures an effective, yielding restraint of relative movements between adjacent regions of the rigid element 2.

The rigid element 2 is advantageously formed by a metal sheet, the slenderness of which is limited to values such as to ensure that it behaves as a plate and not as a foil or film.

Even more advantageously, the rigid element 2 is formed by a steel sheet, preferably of stainless steel with a thickness of from 0.5 to 1.0 mm. The pliable element 3 is advantageously made of a closed-cell expanded material, preferably polyurethane, having a thickness of from 10 to 50 mm, preferably 20 mm.

The protective sheet 4 is preferably made of metal, for example, aluminium, but it could also be formed by a stainless-steel sheet.

An advantageous method of producing the constructional element 1 by lamination on two continuous strips will be described below with reference to Figure 9.

A mixture 8 of polyisocyanates and polyhydroxylic compounds for forming the pliable element 3 is deposited on the surface of a stainless-steel sheet 7, for example 0.6 mm thick, which will form the rigid element 2. The mixture 8 is polymerized in the presence of catalysts, surfactants, flame retardants and liquid expanding agents, by propagation reactions which increase the molecular weight and the viscosity of the reagents. During the polymerization process, the polymer, which up to this point is soluble and fusible, is rendered insoluble and infusible by further cross- linking reactions.

The heat generated by the reaction which, as a whole, is endothermic, vaporizes the expanding agent, forming a gas which remains caught in the form of very small bubbles in the polymer being formed, determining its density and thermal-insulation properties.

According to a particularly advantageous embodiment, the pliable element 3 is made of expanded polyurethane having a density of from 30 kg/m³ to 60 kg/m³, preferably from 44 kg/m³ to 50 kg/m³, and even more preferably about 48 kg/m³.

In the course of or after the polymerization process, the protective sheet 4, preferably of aluminium with a thickness of from 50 to 100 micrometres, is applied to the exposed surface of the pliable element 3 being formed.

Naturally, the protective sheet 4 may also be formed by a sheet of stainless-steel or another suitable material. If the pliable element 3 is already sufficiently protective in itself, the protective sheet

4 may even be omitted.

After a pressure stage with subsequent cooling, the continuous sandwich panel is cut into individual, substantially rectangular constructional elements 1. The final dimensions of the constructional elements 1 depend substantially on transportation requirements.

The main steps for the production of a duct 10 for aeriform media by means of a constructional element 1 according to the invention are described below with reference to Figures 4 and 5.

One or more constructional elements 1 which are to form the walls of the duct 10, are produced from a constructional element 1 of larger size by cutting along profile lines 11. Preferably, the cut surfaces 12 are not perpendicular to the smooth surface 5 but are inclined so as to form a larger connection area.

The constructional elements 1 are then connected along their opposed sides 13, 13', without the use of further connection members or reinforcing means, to form a gas-tight, tubular body 14 which defines, by means of the smooth surfaces 5, a conveyor space 15.

The individual constructional elements 1 are advantageously connected by gluing of their opposed sides 13 and 13' over the entire cut surface 12.

During the connection of the constructional elements 1, a gap is formed in the joint between the side edges 9, 9' of the rigid elements 2 and is sealed in a leaktight manner with a substantially impermeable sealing material, for example, with silicone. According to one embodiment of the invention, the gap in the joint is sealed by welding or brazing so as to achieve continuity of material.

The constructional elements 1 are advantageously glued by means of a glue based on neoprene rubber, synthetic resins and organic solvents such as aliphatic hydrocarbons and esters.

Even more advantageously, in particular with reference to its use in the food and hospital fields, the constructional elements 1 are glued by means of a completely solvent-free glue, for example, based on water and modified rubber latex.

In the example of Figure 4c, the conveyor duct 10 has a rectangular cross-section formed by four constructional elements 1.

To produce extensive and branched conveyor systems, the individual duct portions 10 are connected to one another along the end faces 16 to form a tubular structure substantially impermeable to gases. Whereas the formation of the cross-section of the duct 10 by the gluing of the constructional elements 1 is definitive and substantially irreversible, the connection between the various duct portions 10 in a longitudinal direction may advantageously be releasable, for example, by means of suitable connection members, which can render the conveyor system very versatile and adaptable to structural or functional modifications of the building in which it is installed.

The connection members may comprise metal flanges which can be fixed to the end faces 16 of the duct portions 10 and which can be connected to one another by geometrical coupling or by further connection members.

Figure 5 shows a constructional element 1 by means of which elbow-shaped duct portions 10 are produced, substantially and advantageously, by the same method as is described above with reference to Figure 4.

The constructional elements 1 which form the curved walls may be shaped irreversibly, for example, by means of a plurality of folds 17 substantially parallel to the bend axis, or may be held in the deformed configuration by being glued to the substantially flat lateral constructional elements.

The constructional element 1 according to the invention enables conveyor ducts 10 with cross-sections of any shape to be constructed, as can be seen, for example, from Figures 6a to 6f. Figure 6f, for example, shows the cross-section of a duct 10 which comprises two conveyor spaces 15 and 15' separated by a dividing wall 18 formed by a constructional element 1 the protective sheet 4 of which, to all intents and purposes, performs the function of the rigid element 2 and is therefore preferably made of the same material, although the respective thicknesses do not have to be identical.

The operation of a conveyor system 20 according to the invention formed by the constructional elements 1 according to the invention is described below.

The constructional elements 1 are advantageously transported to the place in which they are to be installed, in the form of rectangular elements of dimensions suitable for transportation. Once they have arrived on site, the constructional elements 1 are cut and glued to form substantially gas-tight, self- supporting and thermally-insulating, tubular portions 10. These duct portions 10 are connected to one another to form the conveyor system 20, for example, for conditioned air, in which any branches and forks are formed by fork portions .10', also advantageously produced by means of the same constructional elements 1, as shown, for example, in Figure 7. After the conveyor system 20 has been connected to the other modules of the air-conditioning system, it is ready for use.

The conveyor system 20 produced by means of the constructional elements 1 has very advantageous characteristics in operation. Figure 8 shows the acoustic behaviour of a duct wall in response to an air-flow 19 inside the conveyor space 15. The vibrations of the walls excited by the air-flow 19 are attenuated to an unusual extent by virtue of the yielding restraint offered to relative movements of adjacent regions of the rigid element 2, which behaves substantially as a continuously elastic supported plate. As a result, not only noise due to the air-flow 19 conveyed, but also the transmission of the noise of the fans of the conveyor system, as well as the acoustic connection between different areas of a building or of an industrial plant, are effectively prevented. This effect is further enhanced by virtue of the smooth and flat surface 5 of the rigid element 2 which defines the conveyor space 15, preventing separation of the flow from the walls and consequently the formation of undesired vortices and turbulence.

The fact that the surface 5 is very smooth and resistant both to corrosion and to local deformation, particularly when the rigid element 2 is made of stainless steel, prevents damage to the surface 5 and the formation of recesses which are responsible for the deposition of dirt and for the formation of colonies of bacteria as well as for the formation of vortices and turbulence in the air-flow. These characteristics render the constructional element 1 particularly usable in critical areas such as in hospitals, in the food industry, in the semiconductor industry, and the like.

The conveyor system 20 according to the invention also has extremely uniform thermal-insulation and structural characteristics which in turn permit a precise calculation of heat and pressure losses, and hence economical and reliable operation of the air- conditioning system. Moreover, the constructional element 1 has characteristics such as to permit the creation of conveyor systems of any desired shape, ensuring a high degree of impermeability and structural strength.

The constructional element 1 is suitable for the creation of low-pressure, medium-pressure, and high- pressure conveyor systems. By virtue of the fact that it is in itself thermally-insulating and self-protective, it presents no difficulty with regard to fitting and insulation in spaces to which access is difficult. The constructional element 1 according to the invention requires no reinforcing profiles.

For some applications, there may be provision either for an increase in the thickness of the rigid element 2, or for the incorporation of a reinforcing structure in the pliable element 3, whilst the local pliability of its material nevertheless remains unchanged.

The conveyor system 20 according to the invention is particularly quiet, greatly limiting the amplitude of vibrations and completely preventing "knocking" due to warping.

The conveyor system 20 can also be dismantled and subsequently refitted without separate dismantling of the individual functional elements, as took place in the prior art.

Naturally, since it is a prefabricated product, the constructional element, and consequently also the conveyor system, has all of the related advantages with regard to quality, tolerances and, in particular, limitation of waste during assembly. Inspection openings and other accessories can be installed according to specific requirements, either during the manufacture of the constructional element 1 or on site.

Naturally, in order to satisfy contingent and specific requirements, a person skilled in the art may apply to the constructional element 1 according to the present invention further modifications and variations all of which, however, are included within the scope of protection of the invention as defined by the appended claims.

Claims

1. Prefabricated constructional element (1) for the creation of a conveyor system (20) for aeriform media, in particular for conditioned air (19), comprising: - a rigid, substantially plate-shaped element (2) resistant to local deformation, having at least one substantially smooth surface (5) which is impermeable to gases, for defining a conveyor space (15), a substantially plate-shaped and thermally insulating pliable element (3) having less stiffness than the rigid element (2), in which the pliable element (3) is connected uniformly to the rigid element (2) along the surface remote from the at least one smooth surface (5) to form the prefabricated constructional element (1), achieving a yielding relative restraint of the rigid element (2) over its whole extent.

2. Constructional element (1) according to Claim 1 in which the rigid element (2) and the pliable element (3) have substantially uniform thicknesses.

3. Constructional element (1) according to Claim 1 or Claim 2 in which the rigid element (2) and the pliable element (3) are shaped together.

4. Constructional element (1) according to any one of the preceding claims, in which the rigid element (2) and the pliable element (3) are connected continuously over the whole surface.

5. Constructional element (1) according to any one of the preceding claims in which the rigid element (2) and the pliable element (3) are connected in distinct connection regions (6) distributed uniformly over the whole extent of the rigid element (2) .

6. Constructional element (1) according to Claim 5 in which the connection regions (6) extend substantially along parallel lines.

7. Constructional element (1) according to any one of the preceding claims, comprising a protective sheet (4) associated with the surface of the pliable element (3) remote from the rigid element (2) .

8. Constructional element (1) according to any one of the preceding claims, in which the rigid element (2) is made of sheet metal.

9. Constructional element (1) according to Claim 8 in which the rigid element (2) is made of stainless steel.

10. Constructional element (1) according to any one of the preceding claims in which the pliable element (3) is made of a material selected from the group comprising closed-cell expanded resins.

11. Constructional element (1) according to Claim 10 in which the pliable element (3) is made of expanded polyurethane .

12. Constructional element (1) according to any one of the preceding claims in which the protective sheet (4) is made of aluminium.

13. Constructional element (1) according to any one of the preceding claims in which the protective sheet (4) is made of stainless steel.

14. Constructional element (1) according to any one of the preceding claims, produced from a constructional element (1) of larger size by cutting along profile lines (11) .

15. Conveyor duct (10) constituted by one or more constructional elements (1) according to any one of the preceding claims, in which the one or more constructional elements are connected in a substantially gas-impermeable manner along opposed sides (13, 13') to form a tubular body (14) delimiting the conveyor space (15) by means of the smooth surface (5) .

16. Conveyor duct (10) according to Claim 15, produced by gluing of the sides (13, 13') over their entire cut surface (12) .

17. Conveyor duct (10) according to Claim 16, glued with a water-based, solvent-free glue.

18. Conveyor duct (10) according to Claim 16, glued with a glue based on neoprene rubber and synthetic resins .

19. Conveyor duct (10) according to any one of Claims 15 to 18 in which a gap formed in the joint between lateral edges (9, 9') of the one or more rigid elements (2) is sealed in a leaktight manner with a substantially impermeable sealing material.

20. Conveyor duct (10) according to Clim 19 in which the sealing material comprises silicone.

21. Conveyor duct (10) according to Claim 18 in which the gap in the joint is sealed by welding or brazing.

22. Conveyor duct (10) according to any one of Claims 15 to 21 having a substantially rectangular cross-section formed by four constructional elements

(1) •

23. Conveyor system (20) comprising one or more ducts (10) according to any one of Claims 15 to 22, connected to one another along end faces (16) to form a tubular structure substantially impermeable to gases, except for the openings provided.

24. Conveyor system (20) according to Claim 23 in which the ducts (10) are connected to one another along lateral sides to form a branched tubular structure.

25. Conveyor system (20) according to Claim 23 or Claim 24 in which the connections are releasable.