WO2004001298A1

WO2004001298A1 - Air duct and an arrangement with an air duct, which has a cross-section with two longer sides and two shorter

Info

Publication number: WO2004001298A1
Application number: PCT/FI2003/000486
Authority: WO
Inventors: Rauno Juuti
Original assignee: Uponor Innovation Ab
Priority date: 2002-06-19
Filing date: 2003-06-16
Publication date: 2003-12-31
Also published as: EP1532406A1; FI20021198A; FI20021198A0; AU2003240921A1

Abstract

An air duct (1) has a flat cross-section, whereby the cross-section of the air duct (1) includes two longer sides and two shorter sides. The air duct (1), at least in one longer side of the cross-section in its middle part, may be provided with a ridge (2) such that a force affecting the ridge (2) and trying to flatten the air duct (1) is at least partly divided sidewardly. Fasteners (3) can be used for preventing edges of the air duct (1) from moving sideways away from each other due to the force flattening the air duct.

Description

Air duct and an arrangement with an air duct, which has a cross-section with two longer sides and two shorter.

FIELD OF THE INVENTION

[0001] The invention relates to an air duct having a flat cross- section, whereby the cross-section of the air duct includes two longer sides and two shorter sides.

[0002] The invention further relates to an arrangement in connection with an air duct, the arrangement comprising an air duct having a flat cross- section, whereby the cross-section of the air duct includes two longer sides and two shorter sides, and fasteners for fastening the air duct.

BACKGROUND OF THE INVENTION

[0003] Usually, air ducts are circular channels made of metal or plastic. Such circular air ducts require rather much installation space. Therefore, they are rather difficult to use and install. Taking up much space, they do not suit all targets e.g. with limited installation height. In practice, there is not enough room for a circular air duct inside a wall or in floor or intermediate floor concreting structures.

[0004] Consequently, air ducts having a rectangular cross-section have been used in places of limited size. An air duct having a rectangular cross-section easily changes its shape, however, which causes problems e.g. with tightness. Furthermore, changes in the shape of a longer side of the cross-section of the channel may cause undesired whistling noises caused by air flows. Furthermore, the use of rectangular channels inside concreting structures is rather limited since the weight and buoyancy of concrete grout may quite easily buckle the air duct.

BRIEF DESCRIPTION OF THE INVENTION

[0005] An object of the present invention is to provide a novel air duct and a novel arrangement in connection with the same.

[0006] The air duct of the invention is characterized in that the air duct is, at least in one longer side of the cross-section in its middle part, pro- vided with a ridge in a longitudinal direction of the air duct such that a force affecting the ridge and trying to flatten the air duct is at least partly divided sideward ly.

[0007] Furthermore, the arrangement of the invention is characterized in that the cross-section of the air duct is higher in a middle part of a longer side than at edges thereof, and that the fasteners are arranged to prevent the edges of the air duct from moving away from each other when the air duct is subjected to a force trying to flatten the same.

[0008] The cross-section of the air duct is flat, whereby the cross- section of the air duct includes two longer and two shorter sides. Preferably, the air duct is, at least in one longer side of the cross-section in its middle part, provided with a ridge such that a force affecting the ridge and trying to flatten the air duct is at least partly divided sidewardly. Preferably, fasteners are used for preventing the edges of the air duct from moving sideways away from each other due to the force flattening the air duct. When the cross-section of the flat air duct is higher in a middle part of a longer side than at edges thereof, the channel can be prevented from buckling by using fasteners preventing the edges from moving. Preferably, the fasteners are arranged to simultaneously keep the air duct in place also in a vertical direction. Preferably, the corners of the air duct are rounded.

[0009] An advantage of the solution is that the air duct takes only relatively little space in a thickness direction. All in all, the air duct is strong, and e.g. joints can be sealed extremely well. Furthermore, the air duct does not buckle very easily even if e.g. its wider side is subjected to a force flatten- ing the channel since the ridge in the air duct divides the flattening force sidewardly and/or the air duct is provided with fasteners preventing the edges of the channel from moving. Furthermore, the fasteners enable the air duct to remain in a desired position and in its place e.g. during a concreting procedure, in which case e.g. the buoyancy of concrete grout does not substantially lift the air duct. Rounding the corners of the air duct makes the channel extremely good in terms of flow technique. Similarly, a channel equipped with rounded corners is easier to clean and it stays clean.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention will be described in closer detail in the accom- panying drawings, in which

[0011] Figure 1 is a schematic, axonometric view showing an air duct,

[0012] Figure 2 is a schematic, cross-sectional end view showing the air duct of Figure 1 , [0013] Figure 3 schematically shows a fastener for fastening an air duct,

[0014] Figure 4 schematically shows a cross-section of a second air duct, [0015] Figure 5 schematically shows a cross-section of a third air duct,

[0016] Figure 6 schematically shows a cross-section of a fourth air duct,

[0017] Figure 7 schematically shows a cross-section of a fifth air duct, and

[0018] Figure 8 schematically shows a cross-section of a sixth air duct.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Figure 1 shows a flat air duct or ventilation channel 1. The longer sides of the air duct 1 are both provided with a ridge 2 in a longitudinal direction of the air duct 1. The air duct 1 can be made of metal, such as aluminium. Most preferably, however, the air duct 1 is made of plastic, in which case the air duct is inexpensive to manufacture and advantageous to use. The material of the air duct 1 is preferably polyolefin, such as polyethene PE or polypropylene PP. Particularly preferably, a fire retardant, such as aluminium trihydroxide or a halogenated fire retardant and/or an antistatic agent, such as carbon black, has been added to this material. An alternative is that the air duct 1 is a multilayer channel such that an inner layer of the air duct 1 includes an antistatic agent and/or an outer layer of the air duct includes a fire retardant. Adding an antistatic agent helps preventing static electricity from being formed while a fire retardant enables the air duct to be provided with good fire endurance characteristics. Furthermore, the inner layer of the air duct may be foamed.

[0020] Figure 2 is a cross-sectional end view showing the air duct 1. The air duct 1 is flat, which, in connection with the present description, means that the ratio of a width L of the cross-section of the air duct to a height H thereof is more than 1.5. Most preferably, L:H>4. In such a case, the cross- section of the flat air duct thus includes two longer sides in a width direction and two shorter sides, i.e. edges, in a height direction. In the example of Figure 2, the width L is 250 mm and the height H is 50 mm. The length of the outer circumference of the air duct 1 of Figure 2 is thus in a similar range to that of the outer circumference of a circular air duct having a 160 mm diameter.

[0021] To ensure the strength of the structure of the air duct, the air duct is provided with a ridge 2. The ridge 2 is formed in such a manner that a force Fi flattening the channel 1 is also partly divided sidewardly as shown by arrows F₂. In such a case, the forces illustrated by arrows F₂ thus try to squeeze the edges of the air duct outwardly. If the structure of the air duct is rigid enough in this direction, the air duct 1 does not buckle inwardly, in spite of the force F-i. The ridge 2 is formed in a middle part of a long side of the cross- section of the air duct, the distance between the ridge 2 and an edge of the air duct thus being at least 1/3 of the width L of the cross-section of the air duct. Most preferably, the ridge 2 is formed in a middle part of a long side of the air duct 1 , whereby the force Fi flattening the channel 1 is divided evenly also sidewardly as shown by arrows F₂. For the sake of structural rigidity of the air duct, the ridge 2 should be as pointed as possible. In order to enable the air duct 1 to be installed in as flat a space as possible, the height H should, however, be as small as possible. The cross-section of structure of the air duct 1 is formed such that between the ridge 2 and a point equipped with designation a, a wall is substantially straight. Between a point equipped with designation a and a point equipped with designation b, the wall is slightly curved such that a radius of curvature Ri is extremely large, in the case of Figure 2 e.g. in the range of 600 mm. Between designations b and c, the wall is curved such that a radius of curvature R₂ is in the range of 10 mm. Between designations c and d, the wall is straight again. Most preferably, the air duct is symmetric with re- spect to both the vertical and the horizontal plane. The air duct 1 is then easy to manufacture and its appropriate use is easy to ensure since it does not matter which way the air duct is to be installed. In the example of Figure 2, the thickness of the wall of the air duct 1 is typically in the range of 3 to 4 mm. At the ridge 2, the straight wall portions may constitute a corner with no radius of curvature existing at the ridge 2 at all. For the sake of easiness of installation, however, it is advisable that at the ridge 2 the radius of curvature of an inner surface be e.g. 0.1 to 2 mm and the radius of curvature of an outer surface e.g. 2 to 5 mm. At the ridge 2, an angle α between the walls is small enough for the force Fi to be divided in the direction of arrows F₂ as well. Preferably, the an- gle α is less than 175°. [0022] Figure 3 shows a fastener 3. Such fasteners 3 enable the edges of the air duct 1 to be prevented from moving sideways away from each other. The force trying to cause such a movement is thus the force F-i, causing a force in the direction of arrows F₂. When the movement of the edges of the air duct 1 is prevented utilizing the fasteners 3, the air duct 1 is not allowed to change its shape, which enables flattening, i.e. compression, of the air duct 1 to be prevented in a particularly efficient manner. The force F-i may thus be caused e.g. by the weight of concrete grout or, similarly, the particular force may be caused underneath the air duct by the buoyancy of concrete grout. Since the fasteners 3 prevent the edges of the air duct 1 from moving away from each other, the fasteners 3 reduce the risk of buckling of a flat air duct 1 whose cross-section is higher in a middle part of a longer side than at the edges thereof. In order to fasten a fastener 3 in its place e.g. in a body of a building, the fastener 3 is provided with a hole 4 which enables the fastener 3 to be fastened e.g. by a screw or a nail or another appropriate device, such as a peg or a pin. Furthermore, the fastener 3 may be fastened e.g. by gluing or binding or wedging, or in another manner.

[0023] The fastener 3 includes an upper support 5 and a lower support 6, both resembling a wedge, the air duct 1 being arranged between a slot formed by such supports. The slot of the fastener 3 is shaped to correspond to the shape of the air duct 1. The wedge-like lower support 6 stabilizes the air duct 1 in its place, preventing it from swaying and turning around a lower ridge 2. The wedge-like nature of the upper support 5, again, ensures that the upper part of the fastener 3 does not rise higher than the highest point of the air duct 1 , i.e. the point at the ridge 2. The upper support 5 prevents the air duct 1 from rising upwardly due to the buoyancy caused by the concrete cast, e.g. while carrying out concrete casting. For the sake of rigidity of the upper support 5, the shape of the fastener 3 includes supporting structures, such as diagonal supports 7, in a bottom part of the slot. Most preferably, the fasteners 3 are fastened on both sides of the air duct 1 , at the same point. In connection with the air duct of Figure 2, the fasteners 3 may be arranged in the concrete grout e.g. at intervals of 30 to 50 cm. If the air duct is installed in a wall or in a ceiling, wherein the air duct is not subjected to any extremely strong force effects, the fasteners 3 may be arranged at longer intervals. It is also possible to ar- range the fasteners 3 on different sides of the air duct in the longitudinal direction thereof, at a distance from each other. [0024] Figure 4 shows an air duct 1 whose cross-section includes substantially no straight parts in a wall. Approaching a ridge 2, however, a tangent of a wall never becomes 0° but the angle between tangents is no more than 175°. [0025] Figure 5 shows an air duct 1 wherein a wall is curved at ridges 2 as well. Despite the curvature of the wall, the ridge 2 is, however, such that the force flattening the air duct 1 is divided sidewardly as seen in Figure 5 as well. When the corners are as rounded as possible and their radius of curvature is as large as possible, the air duct 1 is advantageous in terms of flow technique, collecting no substantial dirt or dust. The air duct 1 is thus simple and easy to clean.

[0026] Figure 6 shows an air duct 1 wherein a wall is made up of straight parts. When an angle α is more than 175°, the structure of the air duct 1 is stronger than that of a rectangular channel. Furthermore, when no angle is less than 92°, the air duct is easier to clean than a rectangular channel.

[0027] The solution of Figure 7 also comprises an air duct 1 that is made up of straight parts. In the solution of Figure 7, however, no angle is less than 120°, in which case the flow and cleanness characteristics of the air duct 1 are relatively good. [0028] Figure 8 shows a flat air duct 1 whose bottom is straight and whose top is provided with a ridge 2. In such a case, the even bottom enables the air duct 1 to be easily and firmly installed e.g. on a floor while thanks to the ridge 2 the air duct 1 endures e.g. the weight caused by concrete grout.

[0029] The drawings and the related description are only intended to illustrate the idea of the invention. In its details, the invention may vary within the scope of the claims.

Claims

1. An air duct having a flat cross-section, whereby the cross-section of the air duct (1) includes two longer sides and two shorter sides, characterized in that the air duct (1) is, at least in one longer side of the cross- section in its middle part, provided with a ridge (2) in a longitudinal direction of the air duct (1) such that a force (Fi) affecting the ridge (2) and trying to flatten the air duct (1) is at least partly divided sidewardly.

2. An air duct as claimed in claim ^ characterized in that the ridge (2) is located in the middle of a longer side of the cross-section of the air duct (1).

3. An air duct as claimed in claim 1 or 2, characterized in that both of the longer sides of the cross-section of the air duct (1) are provided with a ridge (2).

4. An air duct as claimed in any one of the preceding claims, characterized in that the cross-sectional structure of the air duct (1 ) is symmetrical.

5. An air duct as claimed in any one of the preceding claims, characterized in that an angle (α) between walls adjacent to the ridge (2) or between tangents of the walls is less than 175°.

6. An air duct as claimed in any one of the preceding claims, characterized in that the corners of the air duct are rounded.

7. An air duct as claimed in any one of the preceding claims, characterized in that the shape of the cross section of the air duct (1) includes a straight wall portion between the ridge (2) and edges of the air duct (1 ) while the corners of the shorter sides of the air duct are rounded.

8. An air duct as claimed in any one of the preceding claims, characterized in that the air duct is made of polyolefin.

9. An air duct as claimed in claim 8, characterized in that a fire retardant and/or an antistatic agent has been added to the polyolefin.

10. An air duct as claimed in claim 8 or 9, characterized in that the wall of the air duct (1) is a multilayer wall such that an inner layer of the air duct includes an antistatic agent added to the polyolefin and an outer layer includes a fire retardant added to the polyolefin.

11. An air duct as claimed in claim 10, characterized in that the inner layer of the air duct is foamed.

12. An arrangement in connection with an air duct, the arrangement comprising an air duct (1) having a flat cross-section, whereby the cross- section of the air duct includes two longer sides and two shorter sides, and fasteners (3) for fastening the air duct (1), characterized in that the cross section of the air duct (1) is higher in a middle part of a longer side than at edges thereof, and that the fasteners are arranged to prevent the edges of the air duct from moving away from each other when the air duct is subjected to a force (Fi) trying to flatten the same.

13. An arrangement as claimed in claim 12, characterized in that the air duct (1) is, at least in one longer side of the cross-section in its middle part, provided with a ridge (2) in a longitudinal direction of the air duct (1) such that a force (Fi) affecting the ridge (2) and trying to flatten the air duct (1) is at least partly divided sidewardly.

14. An arrangement as claimed in claim 12 or 13, character- i z e d in that the cross-sectional structure of the air duct is symmetrical.

15. An arrangement as claimed in any one of claims 12 to 14, characterized in that a fastener (3) is provided with a wedge-like lower support (6).

16. An arrangement as claimed in any one of claims 12 to 15, characterized in that the fastener is provided with an upper support (5) extending at least partly above the air duct (1).

17. An arrangement as claimed in any one of claims 12 to 16, characterized in that the fastener includes a lower support (6) and an upper support (5), the air duct (1) being arranged in a slot formed by such sup- ports.