WO2006071166A1

WO2006071166A1 - Baffle sound damper

Info

Publication number: WO2006071166A1
Application number: PCT/SE2005/001723
Authority: WO
Inventors: Tobias SAGSTRÖM
Original assignee: Fläkt Woods AB
Priority date: 2004-12-29
Filing date: 2005-11-16
Publication date: 2006-07-06
Also published as: SE0403186D0; SE0403186L

Abstract

A baffle sound damper (2), which will be mounted in an air duct or in an air duct element (1), in which the baffle comprises a main body (15), which consists of a sound absorptive material (3), which is completely covered with a sound transmitting material (4), and in which the mounting of the baffle (2) is done in such a way, that a gap (17) always will be secured between the bottom covering (14) of the baffle and the bottom plate (18) of the air duct as well as in that mutual positions between the various baffles also will be controlled by means of the adjustment support (5).

Description

BAFFLE SOUND DAMPER

The present invention relates to a baffle sound, damper, in the following text called a baffle, its construction and functions being set forth in claim 1.

In air conditioning plants there are often in the flow conduits, in the air ducts, sound absorptive devices, so called baffles, designed to dampen the noise, which is caused by fans in the system, which fans increase the pressure and the speed of the air flow. These sound absorption devices often comprise one or several baffles, which are made of a sound absorptive material.

It is typical of existing or known baffle constructions, that they are made of one or several layers of sound absorptive materials, which entirely or at least partially are covered by some form of sheet material layer to make them more stable and provide fastening means to the surrounding air duct.

In several patent documents the above-mentioned baffle constructions are described. Li e.g. WO 03/073015 Al the construction of the baffle element is explained, the characterizing features comprising different densities of the sound absorptive material within one and the same baffle.

DE 39 43 078 also relates to the design and to the mounting of an air duct.

Patent document DE 101 21 940 C relates to a baffle design, which is constructed on a plate frame, which in its core comprises an isolation material. This construction has substantial drawbacks like other existing similar constructions.

In all these cases and also in other similar constructions the starting position is, that the baffle element is to be provided with a surface layer, which mainly consists of sheet materials, partly to obtain a supporting function and means to fasten these materials to the air duct and partly to protect the isolation material itself against the air stream.

Since existing baffle element have the constructions, which are described in the above-cited patent documents as well as are the baffle elements, which normally are used as sound absorptive elements, a number of negative factors are obtained, the object of the present invention being to eliminate these negative factors. The most important negative factors in existing constructions comprise:

-the risk of growth of bacteria between the various plates/plate joints, which exist or will exist in the baffle elements;

-undamped air flow paths between baffle plates and duct plates resulting in, that the noise level remains unacceptably high;

-a direct contact probably existing between baffle plates and plates of the duct bottom, which may result in corrosion problems as well as sanitary problems;

-a high weight of the finished baffle because of the baffle plates; and

-a high cost of the finished baffle due to the baffle plates.

All these drawbacks will be eliminated by means of the construction according to the present invention. The description of the invention and the enclosed drawings will explain this, in which drawings:

Fig. 1 shows an air duct element with mounted baffle elements; Fig. 2 shows the same air duct element, but in this case only two baffle elements, of altogether three, have been mounted;

Fig. 3 shows the baffle element, in which the views of a few sections show examples of alternative designs of the baffle;

Fig. 4 shows a design of a large baffle provided with a built-in stiffening element; Fig. 5 is an example showing how the baffle in inserted into and fastened in the air duct element; and

Fig. 6 is an example showing how the adjustment supports can be designed.

The design of the sound absorptive unit, baffle element 2, according to the invention, mainly comprises a main body 15 with a sound absorptive material 3, which is completely covered by a sound transmitting material 4. This special design of the construction offers several benefits, which thus eliminate the drawbacks, which known construction solutions are impaired by.

Fig. 1 shows a basic construction of an air duct element 1. In this case three baffles 2 have been mounted, which are retained in place by adjustment supports 5, which are removably and slidingly mounted on a rail 6, mounted transversely to the longitudinal direction of air duct 1 and in the lower as well as the upper part of the duct and in the front as well as the rear zone of the duct, seen in the air flow direction. The mutual distance between baffles 2 is controlled by adjustment supports 5. In Fig. 2 a lateral wall section 22 has been removed from air duct element 1. In this figure one of baffles 2 has not yet been mounted in air duct element 1. In this figure partly rail 6 can be seen and partly an adjustment support 5, which will retain the baffles in place. In some cases baffles 2 can also be mounted in a horizontal direction, but this does not influence the fundamental construction of the baffles. The fastening in air duct element 1 may mainly be the same as the fastening described above, but some modified fastening elements may also be used.

A baffle 2 is shown in Fig. 3 as well as a few embodiments showing how this baffle is constructed. The baffle comprises a sound absorptive material 3, which is completely build into or is surrounded by a sound transmitting material 4. Sound absorptive material 3 will normally be a polyester material or a mineral wool material, e.g. rock wool or glass wool. Sound transmitting surface material 4 suitably is a polyester material or a glass fiber material having properties allowing it to meet the authority requirements, which normally exist as to air treatment installations and in that case e.g. involving fire classification, emission from the material, and guaranteeing, that there is no breeding ground for microorganisms and that it is possible to clean the construction.

Fig. 3 shows, that baffle element 2 kan be constructed in several different ways. The baffle elements normally have lengths and heights of about from 0.5 to 2 m and thicknesses of about from 0.1 to 0.5 m. The basic construction principle is, that sound transmitting surface material 4 will enclose the entire baffle. Long sides 12 as well as short sides 13 of the baffle can be made in one piece of sound transmitting material 4, which at the top and at the bottom respectively is tightly attached, via e.g. gluing or some form of enclosure means, to this material . Thus, by gluing surfaces 12 and 13 respectively can be spliced to obtain a top and a bottom covering 14 respevtively, according to view B-B. The surface material can e.g. also manufactured as a bag, which only is to sealed, glued together, in its open end subsequent to its mounting on top of the sound absorptive material.

Normally the baffles are to be designed with a rectangular main body 15, but the shape of them can of course be modified within the scope of the inventive idea. In the present description only the rectangular basic shape of main body 15, for the sake of simplicity, is used in the shown figures.

In Fig. 3 only a few embodiments have been shown, showing how the basic geometric shape in a simple way can be modified within the scope of the inventive idea. Thus, baffle 2 can e.g. be designed according to an alternative A with a type of semi cylinder 8, made of a sound absorptive material 3, which is covered by a sound transmitting material 4, mounted in the front end of baffle/main body 15, seen in the direction of the air flow. Semi cylinder 8 can be fastened through e.g. a gluing to main body 15. Through this design an improved flow configuration is obtained, which leads to a reduced flow resistance in the air duct, resulting in a lower fall of pressure.

Semi cylinder 8 can, as an alternative B shows, be replaced with a rectangular part 9, used as a support for the enclosing surface material 4, when it is applied e.g. through gluing against long surfaces 12 and short surfaces 13 of baffle 2. An alternative C shows additional embodiments of the design of the baffle, in which rectangular part 9 has been modified and in which sound transmitting material 4 has been shaped otherwise on top of part 9.

Baffle 2 can of course be constructed with a sound absorptive material 3, which comprises two or more different properties, e.g. having different densities in order to obtain an improved sound absorption within a wider range of frequencies. This special design is also shown in principle in Fig. 3, an alternative D, in which part 10 is a part with a high density and part 11 is a part with a lower density of sound absorptive material 3. The physical design of and the distribution between different parts, designed with different densities, may present a large number of variations, but the main idea, that different sound absorptive materials may be parts of one and the same baffle, and that these different parts are enclosed by one and the same sound transmitting material, is the fundamental feature of the present invention. In certain applications the air duct element may have large dimensions and in these instances the baffle elements may become so large, that they must be reinforced, or rather be made more rigid, to obtain a reliable stability. Also, in these instances baffle 2 may be made with the same construction design, which has been described with reference to Fig. 3, but a built-in reinforcement element or stiffening part 16 may then be mounted within baffle element 2, which measure is shown in Fig. 4. Various designs - e.g. with angle irons - may of course be used instead of a complete stiffening part or stiffening surface.

Figs. 5 and 6 show a few embodiments of how parts, which will attach baffle 2 to air duct element Ij maybe designed

In fig. 5 - in a sectional view - baffle 2 is mounted in such a fashion, that a gap 17 always is obtained between the lower part/bottom of covering 14 of the baffle and bottom 18 of the air duct. The same thing is true about the relationship between upper part 14 of the baffle and top plate 19 of the air duct, the roof of the duct. A distance between lower part 14 of the baffle and bottom 18 of the air duct is obtained, because the baffle, when it is mounted in the air duct element, will be supported by adjustment support 5, which can be designed according to the embodiment shown in Fig. 6. Adjustment support 5 is inserted in angle rail 6, which in its turn is fastened - by screws 7 - to air duct element 1 and its bottom plate 18 and top plate 19 respectively.

Fig. 6 shows an embodiment of how adjustment support 5 may be designed, by means of which baffle 2 can be retained in place in air duct element 1.

Ajustment support 5 suitably can be made of a plastic material and it may be designed in such a way, that the baffle will be controlled, since adjustment support 5 is provided with a support wall 20, which partially guides in an axial direction but also guides in a lateral direction by a suitable shape, in principle according to Fig. 6. The adjustment support must also guarantee, that lower part 14 of the baffle forms a gap 17 between itself and lower plate 18 of the air duct element. This is suitably done by providing adjustment support 5 with pressed down parts/bosses 21. The adjustment support suitably is displaceably anchored in a rail 6, which is fastened to lower plate 18 of the air duct, the rail extending at right angles to the longitudinal direction of the air duct. The adjustment support will be manufactured with various widths and consequently an optional distance between the baffle and the air duct wall and between the various baffles in one and the same air duct element respectively can be obtained. In order to obtain this desirable mutual distance between the various baffles the adjustment support is to extended and will at its outer end 23 be turned upwards in order to support in the lateral direction the adjacent baffle and air duct wall 22 respectively. In Fig. 6 a few embodiments of the adjustment support for a baffle according to Fig. 3 are shown, design embodiment A in Fig. 6 being designed for the rear part of the exemplified baffles and design embodiment B in Fig. 6 being designed for embodiments A and D.

By developing the present invention in the manner described above conditions have been created, which make it possible to eliminate the drawbacks, which existing baffle constructions are impaired by.

To sum up, it is obvious, that in existing constructions gaps/openings between the baffle plates and the plate surfaces of the duct walls always are obtained. In order to prevent the noise leakage, which then arises, it will be necessary to insert extra or separate sealing. In order to meet the official requirements as to noise absorption in existing constructions it is consequently necessary to take special measures, which leads to great inconveniences. These measures leads to the creation of spaces for dirt and moisture accumulations. A resulting effect of these inconveniences is e.g. the fact, that corrosion problems with resulting moisture and sound leakage may be obtained; also a great risk for the emergence of bacterial growth may arise. None of the drawbacks described above are likely to emerge, in case a baffle noise damper according to the present invention will be used.

Also, since the baffle is constructed by using only washable and wear-resistent materials and does not have any plates in any surface parts, a quite light baffle has been obtained in comparison with conventional baffles. There are additional advantages with the new construction according to the present invention : chiefly cost advantages but also weight advantages as well as the avoidance of plate overlapping, which will result in pockets for dirt and moisture and breeding-grounds for bacteria. Thanks to the construction of the baffle with noise transmitting surface material 4 on all its surfaces an entirely new and improved noise absorption has been obtained. The gaps, which in existing constructions transmit undamped noise, have been completely eliminated. Otherwise, there may in areas in existing constructions exist small gaps between two opposite plate-covered surfaces, between which air and consequently noise in an undamped way may pass.

Thus, the improved total noise damping capability in accordance with the present invention is most advantageous. This is also true for the possibility to economically be able to produce the individual baffle in an efficient way as far as the state of the flow is concerned, i.e. means have been developed allowing a satisfactory noise damping at a low fall of air pressure, which also is a great advantage.

Since it is possible to succeed with the sound absorption also with gaps between the baffle and the duct plates, it has also been possible to completely eliminate risks of corrosive damages to the air duct plates, because there will not be any zones, in which the duct plate abuts a baffle sheet or comes very close to it, a risk of moisture accumulations, dirt and bacterial growth arising, which is the case, in case a conventional construction is used.

Claims

1. A baffle sound damper, called a baffle in the present text, which is designed to be mounted in an air duct in an air duct element (1) and in which the baffle (2) comprises a main body (15), which consists of a sound absorptive material (3), which is covered by a sound transmitting material (4), and in which the main body (15) preferably is provided with a semi cylinder (8), which is mounted and glued, or abuts, against the main body, in its front end, seen in the direction of the air flow and where the mounting of the baffle is done in a way, which always secures a gap (17) between the bottom covering (14) of the baffle and the bottom plate (18) of the air duct and a corresponding gap between the upper part (14) of the baffle and the top plate (19) of the air duct respectively and guarantees, that the gap (17) is obtained by mounting the baffle by an adjustment support (5), which is fastened to a rail (6), which extends at right angles to the longitudinal direction of the air duct and in the lower as well as the upper part of the duct and in the front as well as in the rear zone of the duct, seen in the flow direction of the air, and where the adjustment support (5) secures a suitable distance between the individual baffles as well as to the duct wall (22), c h a r a c t e r i z e d in that the baffle (2) is made of a sound absorptive material (3), which is completely enclosed by, or surrounded by, a sound transmitting material (4) on all the surfaces or sides of the baffle.

2. A baffle according to claim 1, c h a r a c t e r i z e d in that the sound transmitting material (4) preferably is made of a bag, which is glued together along its open end, after its mounting on top of the sound absorptive material (3).

3. A baffle according to claim 1, c h a r a c t e r i z e d in that the sound transmitting material (4) consists of a sheet material, which tightly fits, when it is glued, against the sound absorptive material (3) on all the sides of the main body (15).

4. A baffle according to claim 1, constructed with the sound transmitting surface material (4), which at its upper part and its lower part respectively tightly fits and is attached, via e.g. a gluing or some type of enclosure means, to adjacent layers or surfaces of this material (4), a baffle being obtained, c h a r a c t e r i z e d in that the sound transmitting surface material (4) at its upper part and its lower part tightly fits and is attached, via e.g. a glue, to adjacent layers or surfaces of this material (4), a baffle being obtained, without pockets or zones, in which moisture, dirt and consequently bacterial accumulations are obtained.

5. A baffle according to claim 1, characterized in that a sound absorption occurs along all the surfaces of the baffle and in that consequently no zones appear, in which undamped noise can pass between the baffle (2) and the air duct element (1).

6. A baffle according to claims 1 and 5, characterized in that a sound absorption is attained between the upper covering (14) of the baffle and the upper plate (19) of the air duct element (1) and between other air gaps between the baffle (2) and the air duct element (1).

7. A baffle according to claim 1, characterized in that an adjustment support (5) retains the baffle (2) in a mounting position, which secures a gap (17) between the baffle and the bottom plate (18) of the air duct, and in that the position of the baffle also in a lateral direction is guided by the adjustment support (5), deleterious dirt and bacterial accumulations being minimized.

8. A baffle according to claim 1, characterized in that in the main body (15) a stiffening part (16) is inserted, which is enclosed by the sound absorption material (3) and which is completely covered with the sound absorption material (3) and the sound transmitting material (4).

PART LIST :

1. Air duct element

2. Baffle element 3. Sound absorptive material

4. Sound transmitting material

5. Adjustment support

6. Rail

7. Screw 8. Semi cylinder

9. Rectangular support part

10. Sound transmitting material having low density

11. Sound transmitting material having high density

12. Long side

13. Short side

14. Upper part and lower part covering

15. Main body

16. Stiffening part

17. Gap

18. Bottom plate

19. Top plate or roof

20. Support wall

21. Boss

22. Lateral wall section, air duct wall 23. Outer end of the adjustment support